vb. to empower someone to undertake an action or to take responsibility for a situation. See empowerment.
Nutritional Profile Energy value (calories per serving): Low Protein: High Fat: Low Saturated fat: Low Cholesterol: None Carbohydrates: Moderate Fiber: Moderate Sodium: Low Major vitamin contribution: Vitamin A, folate, vitamin C Major mineral contribution: Potassium, iron
About the Nutrients in This Food Asparagus has some dietary fiber, vitamin A, and vitamin C. It is an excel- lent source of the B vitamin folate. A serving of four cooked asparagus spears (½ inch wide at the base) has 1.2 g dietary fiber, 604 IU vitamin A (26 percent of the R DA for a woman, 20 percent of the R DA for a man), 4.5 mg vitamin C (6 percent of the R DA for a woman, 5 percent of the R DA for a man), and 89 mcg folate (22 percent of the R DA).
The Most Nutritious Way to Serve This Food Fresh, boiled and drained. Canned asparagus may have less than half the nutrients found in freshly cooked spears.
Diets That May Restrict or Exclude This Food Low-sodium diet (canned asparagus)
Buying This Food Look for: Bright green stalks. The tips should be purplish and tightly closed; the stalks should be firm. Asparagus is in season from March through August. Avoid: Wilted stalks and asparagus whose buds have opened.
Storing This Food Store fresh asparagus in the refrigerator. To keep it as crisp as possible, wrap it in a damp paper towel and then put the whole package into a plastic bag. Keeping asparagus cool helps it hold onto its vitamins. At 32°F, asparagus will retain all its folic acid for at least two weeks and nearly 80 percent of its vitamin C for up to five days; at room temperature, it would lose up to 75 percent of its folic acid in three days and 50 percent of the vitamin C in 24 hours.
Preparing This Food The white part of the fresh green asparagus stalk is woody and tasteless, so you can bend the stalk and snap it right at the line where the green begins to turn white. If the skin is very thick, peel it, but save the parings for soup stock.
What Happens When You Cook This Food Chlorophyll, the pigment that makes green vegetables green, is sensitive to acids. When you heat asparagus, its chlorophyll will react chemically with acids in the asparagus or in the cooking water to form pheophytin, which is brown. As a result, cooked asparagus is olive-drab. You can prevent this chemical reaction by cooking the asparagus so quickly that there is no time for the chlorophyll to react with acids, or by cooking it in lots of water (which will dilute the acids), or by leaving the lid off the pot so that the volatile acids can float off into the air. Cooking also changes the texture of asparagus: water escapes from its cells and they collapse. Adding salt to the cooking liquid slows the loss of moisture.
How Other Kinds of Processing Affect This Food Canning. The intense heat of can ning makes asparagus soft, robs it of its bright green color, and reduces the vitamin A, B, and C content by at least half. ( White asparagus, which is bleached to remove the green color, contains about 5 percent of the vitamin A in fresh asparagus.) With its liquid, can ned asparagus, green or white, contains about 90 times the sodium in fresh asparagus ( 348 mg in 3.5 oz. can ned against 4 mg in 3.5 oz. fresh boiled asparagus).
Medical Uses and/or Benefits Lower risk of some birth defects. As many as two of every 1,000 babies born in the United States each year may have cleft palate or a neural tube (spinal cord) defect due to their moth- ers’ not having gotten adequate amounts of folate during pregnancy. The R DA for folate is 400 mcg for healthy adult men and women, 600 mcg for pregnant women, and 500 mcg for women who are nursing. Taking folate supplements before becoming pregnant and through the first two months of pregnancy reduces the risk of cleft palate; taking folate through the entire pregnancy reduces the risk of neural tube defects. Lower risk of heart attack. In the spring of 1998, an analysis of data from the records for more than 80,000 women enrolled in the long-running Nurses’ Health Study at Harvard School of Public Health/Brigham and Woman’s Hospital, in Boston, demonstrated that a diet providing more than 400 mcg folate and 3 mg vitamin B6 daily, from either food or supplements, more than twice the current R DA for each, may reduce a woman’s risk of heart attack by almost 50 percent. Although men were not included in the analysis, the results are assumed to apply to them as well. However, data from a meta-analysis published in the Journal of the American Medical Association in December 2006 called this theory into question. Researchers at Tulane Univer- sity examined the results of 12 controlled studies in which 16,958 patients with preexisting cardiovascular disease were given either folic acid supplements or placebos (“look-alike” pills with no folic acid) for at least six months. The scientists, who found no reduction in the risk of further heart disease or overall death rates among those taking folic acid, concluded that further studies will be required to verify whether taking folic acid supplements reduces the risk of cardiovascular disease.
Adverse Effects Associated with This Food Odorous urine. After eating asparagus, we all excrete the sulfur compound methyl mercap- tan, a smelly waste product, in our urine.
Food/Drug Interactions Anticoagulants. Asparagus is high in vitamin K, a vitamin manufactured naturally by bac- teria in our intestines, an adequate supply of which enables blood to clot normally. Eating foods that contain this vitamin may interfere with the effectiveness of anticoagulants such as heparin and warfarin (Coumadin, Dicumarol, Panwarfin) whose job is to thin blood and dissolve clots.... asparagus
Retroviruses are also used in the development of gene therapy (see GENETIC ENGINEERING).... retrovirus
– the hormone which provokes the adrenal cortex into action.
Symptoms The clinical symptoms appear slowly and depend upon the severity of the underlying disease process. The patient usually complains of appetite and weight loss, nausea, weakness and fatigue. The skin becomes pigmented due to the increased production of ACTH. Faintness, especially on standing, is due to postural HYPOTENSION secondary to aldosterone de?ciency. Women lose their axillary hair and both sexes are liable to develop mental symptoms such as DEPRESSION. Acute episodes – Addisonian crises – may occur, brought on by infection, injury or other stressful events; they are caused by a fall in aldosterone levels, leading to abnormal loss of sodium and water via the kidneys, dehydration, low blood pressure and confusion. Patients may develop increased tanning of the skin from extra pigmentation, with black or blue discoloration of the skin, lips, mouth, rectum and vagina occurring. ANOREXIA, nausea and vomiting are common and the sufferer may feel cold.
Diagnosis This depends on demonstrating impaired serum levels of cortisol and inability of these levels to rise after an injection of ACTH.
Treatment consists in replacement of the de?cient hormones. HYDROCORTISONE tablets are commonly used; some patients also require the salt-retaining hormone, ?udrocortisone. Treatment enables them to lead a completely normal life and to enjoy a normal life expectancy. Before surgery, or if the patient is pregnant and unable to take tablets, injectable hydrocortisone may be needed. Rarely, treated patients may have a crisis, perhaps because they have not been taking their medication or have been vomiting it. Emergency resuscitation is needed with ?uids, salt and sugar. Because of this, all patients should carry a card detailing their condition and necessary management. Treatment of any complicating infections such as tuberculosis is essential. Sometimes DIABETES MELLITUS coexists with Addison’s disease and must be treated.
Secondary adrenal insu?ciency may occur in panhypopituitarism (see PITUITARY GLAND), in patients treated with CORTICOSTEROIDS or after such patients have stopped treatment.... addison’s disease
A severe or life-threatening reaction is often termed ANAPHYLAXIS. Many immune mechanisms also contribute to allergic disorders; however, adverse reactions to drugs, diagnostic materials and other substances often do not involve recognised immunological mechanisms and the term ‘hypersensitivity’ is preferable. (See also IMMUNITY.)
Adverse reactions may manifest themselves as URTICARIA, wheezing or di?culty in breathing owing to spasm of the BRONCHIOLES, swollen joints, nausea, vomiting and headaches. Severe allergic reactions may cause a person to go into SHOCK. Although symptoms of an allergic reaction can usually be controlled, treatment of the underlying conditon is more problematic: hence, the best current approach is for susceptible individuals to ?nd out what it is they are allergic to and avoid those agents. For some people, such as those sensitive to insect venom, IMMUNOTHERAPY or desensitisation is often e?ective. If avoidance measures are unsuccessful and desensitisation ine?ective, the in?ammatory reactions can be controlled with CORTICOSTEROIDS, while the troublesome symptoms can be treated with ANTIHISTAMINE DRUGS and SYMPATHOMIMETICS. All three types of drugs may be needed to treat severe allergic reactions.
One interesting hypothesis is that reduced exposure to infective agents, such as bacteria, in infancy may provoke the development of allergy in later life.
Predicted developments in tackling allergic disorders, according to Professor Stephen Holgate writing in the British Medical Journal (22 January 2000) include:
Identi?cation of the principal environmental factors underlying the increase in incidence, to enable preventive measures to be planned.
Safe and e?ective immunotherapy to prevent and reverse allergic disease.
Treatments that target the protein reactions activated by antigens.
Identi?cation of how IgE is produced in the body, and thus of possible ways to inhibit this process.
Identi?cation of genes affecting people’s susceptibility to allergic disease.... allergy
This technique is used when normal methods of attempted CONCEPTION or ARTIFICIAL INSEMINATION with healthy SEMEN have failed. In the UK, assisted-conception procedures are governed by the Human Fertilisation & Embryology Act 1990, which set up the Human Fertilisation & Embryology Authority (HFEA).
Human Fertilisation & Embryology Act 1990 UK legislation was prompted by the report on in vitro fertilisation produced by a government-appointed committee chaired by Baroness Warnock. This followed the birth, in 1978, of the ?rst ‘test-tube’ baby.
This Act allows regulation monitoring of all treatment centres to ensure that they carry out treatment and research responsibly. It covers any fertilisation that uses donated eggs or sperm (called gametes) – for example, donor insemination or embryos (see EMBRYO) grown outside the human body (known as licensed treatment). The Act also covers research on human embryos with especial emphasis on foolproof labelling and immaculate data collection.
Human Fertilisation & EmbryologyAuthority (HFEA) Set up by the UK government following the Warnock report, the Authority’s 221 members inspect and license centres carrying out fertilisation treatments using donated eggs and sperm. It publishes a code of practice advising centres on how to conduct their activities and maintains a register of information on donors, patients and all treatments. It also reviews routinely progress and research in fertility treatment and the attempted development of human CLONING. Cloning to produce viable embryos (reproductive cloning) is forbidden, but limited licensing of the technique is allowed in specialist centres to enable them to produce cells for medical treatment (therapeutic cloning).
In vitro fertilisation (IVF) In this technique, the female partner receives drugs to enhance OVULATION. Just before the eggs are released from the ovary (see OVARIES), several ripe eggs are collected under ULTRASOUND guidance or through a LAPAROSCOPE. The eggs are incubated with the prepared sperm. About 40 hours later, once the eggs are fertilised, two eggs (three in special circumstances) are transferred into the mother’s UTERUS via the cervix (neck of the womb). Pregnancy should then proceed normally. About one in ?ve IVF pregnancies results in the birth of a child. The success rate is lower in women over 40.
Indications In women with severely damaged FALLOPIAN TUBES, IVF o?ers the only chance of pregnancy. The method is also used in couples with unexplained infertility or with male-factor infertility (where sperms are abnormal or their count low). Women who have had an early or surgically induced MENOPAUSE can become pregnant using donor eggs. A quarter of these pregnancies are multiple – that is, produce twins or more. Twins and triplets are more likely to be premature. The main danger of ovarian stimulation for IVF is hyperstimulation which can cause ovarian cysts. (See OVARIES, DISEASES OF.)... assisted conception
Nutritional Profile Energy value (calories per serving): Moderate Protein: High Fat: Low Saturated fat: Low Cholesterol: None Carbohydrates: High Fiber: Very high Sodium: Low Major vitamin contribution: Vitamin B6, folate Major mineral contribution: Iron, magnesium, zinc
About the Nutrients in This Food Beans are seeds, high in complex carbohydrates including starch and dietary fiber. They have indigestible sugars (stachyose and raffinose), plus insoluble cellulose and lignin in the seed covering and soluble gums and pectins in the bean. The proteins in beans are limited in the essential amino acids methionine and cystine.* All beans are a good source of the B vitamin folate, and iron. One-half cup canned kidney beans has 7.5 g dietary fiber, 65 mcg folate (15 percent of the R DA), and 1.6 mg iron (11 percent of the R DA for a woman, 20 percent of the R DA for a man). Raw beans contain antinutrient chemicals that inactivate enzymes required to digest proteins and carbohydrates. They also contain factors that inactivate vitamin A and also hemagglutinins, substances that make red blood cells clump together. Cooking beans disarms the enzyme inhibi- tors and the anti-vitamin A factors, but not the hemagglutinins. However, the amount of hemagglutinins in the beans is so small that it has no mea- surable effect in your body. * Soybeans are t he only beans t hat contain proteins considered “complete” because t hey contain sufficient amounts of all t he essent ial amino acids. The Folate Content of ½ Cup Cooked Dried Beans
| Bean | Folate (mcg) |
| Black beans | 129 |
| Chickpeas | 191 |
| Kidney beans canned | 65 |
| Navy beans | 128 |
| Pinto beans | 147 |
The Most Nutritious Way to Serve This Food Cooked, to destroy antinutrients. With grains. The proteins in grains are deficient in the essential amino acids lysine and isoleucine but contain sufficient tryptophan, methionine, and cystine; the proteins in beans are exactly the opposite. Together, these foods provide “complete” proteins. With an iron-rich food (meat) or with a vitamin C-rich food (tomatoes). Both enhance your body’s ability to use the iron in the beans. The meat makes your stomach more acid (acid favors iron absorption); the vitamin C may convert the ferric iron in beans into ferrous iron, which is more easily absorbed by the body.
Diets That May Restrict or Exclude This Food Low-calcium diet Low-fiber diet Low-purine (antigout) diet
Buying This Food Look for: Smooth-skinned, uniformly sized, evenly colored beans that are free of stones and debris. The good news about beans sold in plastic bags is that the transparent material gives you a chance to see the beans inside; the bad news is that pyridoxine and pyridoxal, the natural forms of vitamin B6, are very sensitive to light. Avoid: Beans sold in bulk. Some B vitamins, such as vitamin B6 (pyridoxine and pyridoxal), are very sensitive to light. In addition, open bins allow insects into the beans, indicated by tiny holes showing where the bug has burrowed into or through the bean. If you choose to buy in bulk, be sure to check for smooth skinned, uniformly sized, evenly colored beans free of holes, stones, and other debris.
Storing This Food Store beans in air- and moistureproof containers in a cool, dark cabinet where they are pro- tected from heat, light, and insects.
Preparing This Food Wash dried beans and pick them over carefully, discarding damaged or withered beans and any that float. (Only withered beans are light enough to float in water.) Cover the beans with water, bring them to a boil, and then set them aside to soak. When you are ready to use the beans, discard the water in which beans have been soaked. Some of the indigestible sugars in the beans that cause intestinal gas when you eat the beans will leach out into the water, making the beans less “gassy.”
What Happens When You Cook This Food When beans are cooked in liquid, their cells absorb water, swell, and eventually rupture, releasing the pectins and gums and nutrients inside. In addition, cooking destroys antinutri- ents in beans, making them more nutritious and safe to eat.
How Other Kinds of Processing Affect This Food Canning. The heat of canning destroys some of the B vitamins in the beans. Vitamin B is water-soluble. You can recover all the lost B vitamins simply by using the liquid in the can, but the liquid also contains the indigestible sugars that cause intestinal gas when you eat beans. Preprocessing. Preprocessed dried beans have already been soaked. They take less time to cook but are lower in B vitamins.
Medical Uses and/or Benefits Lower risk of some birth defects. As many as two of every 1,000 babies born in the United States each year may have cleft palate or a neural tube (spinal cord) defect due to their moth- ers’ not having gotten adequate amounts of folate during pregnancy. The current R DA for folate is 180 mcg for a woman and 200 mcg for a man, but the FDA now recommends 400 mcg for a woman who is or may become pregnant. Taking a folate supplement before becoming pregnant and continuing through the first two months of pregnancy reduces the risk of cleft palate; taking folate through the entire pregnancy reduces the risk of neural tube defects. Lower risk of heart attack. In the spring of 1998, an analysis of data from the records for more than 80,000 women enrolled in the long-run ning Nurses Health Study at Har vard School of Public Health/ Brigham and Woman’s Hospital in Boston demonstrated that a diet providing more than 400 mcg folate and 3 mg vitamin B6 a day from either food or supple- ments, more than t wice the current R DA for each, may reduce a woman’s risk of heart attack by almost 50 percent. A lthough men were not included in the analysis, the results are assumed to apply to them as well. NOT E : Beans are high in B6 as well as folate. Fruit, green leaf y vegetables, whole grains, meat, fish, poultr y, and shellfish are good sources of vitamin B6. To reduce the levels of serum cholesterol. The gums and pectins in dried beans and peas appear to lower blood levels of cholesterol. Currently there are two theories to explain how this may happen. The first theory is that the pectins in the beans form a gel in your stomach that sops up fats and keeps them from being absorbed by your body. The second is that bacteria in the gut feed on the bean fiber, producing short-chain fatty acids that inhibit the production of cholesterol in your liver. As a source of carbohydrates for people with diabetes. Beans are digested very slowly, produc- ing only a gradual rise in blood-sugar levels. As a result, the body needs less insulin to control blood sugar after eating beans than after eating some other high-carbohydrate foods (such as bread or potato). In studies at the University of Kentucky, a bean, whole-grain, vegetable, and fruit-rich diet developed at the University of Toronto enabled patients with type 1 dia- betes (who do not produce any insulin themselves) to cut their daily insulin intake by 38 percent. Patients with type 2 diabetes (who can produce some insulin) were able to reduce their insulin injections by 98 percent. This diet is in line with the nutritional guidelines of the American Diabetes Association, but people with diabetes should always consult with their doctors and/or dietitians before altering their diet. As a diet aid. Although beans are high in calories, they are also high in bulk (fiber); even a small serving can make you feel full. And, because they are insulin-sparing, they delay the rise in insulin levels that makes us feel hungry again soon after eating. Research at the University of Toronto suggests the insulin-sparing effect may last for several hours after you eat the beans, perhaps until after the next meal.
Adverse Effects Associated with This Food Intestinal gas. All legumes (beans and peas) contain raffinose and stachyose, complex sug- ars that human beings cannot digest. The sugars sit in the gut and are fermented by intestinal bacteria which then produce gas that distends the intestines and makes us uncomfortable. You can lessen this effect by covering the beans with water, bringing them to a boil for three to five minutes, and then setting them aside to soak for four to six hours so that the indigestible sugars leach out in the soaking water, which can be discarded. Alternatively, you may soak the beans for four hours in nine cups of water for every cup of beans, discard the soaking water, and add new water as your recipe directs. Then cook the beans; drain them before serving. Production of uric acid. Purines are the natural metabolic by-products of protein metabo- lism in the body. They eventually break down into uric acid, sharp cr ystals that may concentrate in joints, a condition known as gout. If uric acid cr ystals collect in the urine, the result may be kidney stones. Eating dried beans, which are rich in proteins, may raise the concentration of purines in your body. Although controlling the amount of purines in the diet does not significantly affect the course of gout (which is treated with allopurinol, a drug that prevents the formation of uric acid cr ystals), limiting these foods is still part of many gout regimens.
Food/Drug Interactions Monoamine oxidase (MAO) inhibitors. Monoamine oxidase inhibitors are drugs used to treat depression. They inactivate naturally occurring enzymes in your body that metabolize tyramine, a substance found in many fermented or aged foods. Tyramine constricts blood vessels and increases blood pressure. If you eat a food containing tyramine while you are taking an M AO inhibitor, you cannot effectively eliminate the tyramine from your body. The result may be a hypertensive crisis. Some nutrition guides list dried beans as a food to avoid while using M AO inhibitors.... beans
13.
The ?rst type of damage occurs as an acute episode in which one or more severe blows leads to loss of consciousness and occasionally to death. Death in the acute phase is usually due to intracranial haemorrhage and this carries a mortality of 45 per cent even with the sophisticated surgical techniques currently available. The second type of damage develops over a much longer period and is cumulative, leading to the atrophy of the cerebral cortex and brain stem. The repair processes of the brain are very limited and even after mild concussion it may suffer a small amount of permanent structural damage. Brain-scanning techniques now enable brain damage to be detected during life, and brain damage of the type previously associated with the punch-drunk syndrome is now being detected before obvious clinical signs have developed. Evidence of cerebral atrophy has been found in relatively young boxers including amateurs and those whose careers have been considered successful. The tragedy is that brain damage can only be detected after it has occurred. Many doctors are opposed to boxing, even with the present, more stringent medical precautions taken by those responsible for running the sport. Since the Royal College’s survey in 1969, the British Medical Association and other UK medical organisations have declared their opposition to boxing on medical grounds, as have medical organisations in several other countries.
In 1998, the Dutch Health Council recommended that professional boxing should be banned unless the rules are tightened. It claimed that chronic brain damage is seen in 40–80 per cent of boxers and that one in eight amateur bouts end with a concussed participant.
There is currently no legal basis on which to ban boxing in the UK, although it has been suggested that an injured boxer might one day sue a promoter. One correspondent to the British Medical Journal in 1998 suggested that since medical cover is a legal requirement at boxing promotions, the profession should consider if its members should withdraw participation.... boxing injuries
An appreciation of the need to account for chance and bias has led to development of methods where new treatments are compared to either a PLACEBO or to the standard treatment (or both) in a controlled, randomised clinical trial. ‘Controlled’ means that there is a comparison group of patients not receiving the test intervention, and ‘randomised’ implies that patients have been assigned to one or other treatment group entirely by chance and not because of their doctor’s preference. If possible, trials are ‘double-blind’ – that is, neither the patient nor the investigator knows who is receiving which intervention until after the trial is over. All such trials must follow proper ethical standards with the procedure fully explained to patients and their consent obtained.
The conduct, e?ectiveness and duplication of clinical trials have long been subjects of debate. Apart from occasional discoveries of deliberately fraudulent research (see RESEARCH FRAUD AND MISCONDUCT), the structure of some trials are unsatisfactory, statistical analyses are sometimes disputed and major problems have been the – usually unwitting – duplication of trials and non-publication of some trials, restricting access to their ?ndings. Duplication occurs because no formal international mechanism exists to enable research workers to discover whether a clinical trial they are planning is already underway elsewhere or has been completed but never published, perhaps because the results were negative, or no journal was willing to publish it, or the authors or funding authorities decided not to submit it for publication.
In the mid 1980s a proposal was made for an international register of clinical trials. In 1991 the NHS launched a research and development initiative and, liaising with the COCHRANE COLLABORATION, set out to collect systematically data from published randomised clinical trials. In 1994 the NHS set up a Centre for Reviews and Dissemination which, among other responsibilities, maintains a database of research reviews to provide NHS sta? with relevant information.
These e?orts are hampered by availability of information about trials in progress and unpublished completed trials. With a view to improving accessibility of relevant information, the publishers of Current Science, in 1998, launched an online metaregister of ongoing randomised controlled trials.
Subsequently, in October 1999, the editors of the British Medical Journal and the Lancet argued that the case for an international register of all clinical trials prior to their launch was unanswerable. ‘The public’, they said, ‘has the right to know what research is being funded. Researchers and research funders don’t want to waste resources repeating trials already underway.’ Given the widening recognition of the importance to patients and doctors of the practice of EVIDENCE-BASED MEDICINE, the easy availability of information on planned, ongoing and completed clinical trials is vital. The register was ?nally set up in 2005.... clinical trials
Insulin-dependent and non-insulindependent diabetes have a varied pathological pattern and are caused by the interaction of several genetic and environmental factors.
Insulin-dependent diabetes mellitus (IDDM) (juvenile-onset diabetes, type 1 diabetes) describes subjects with a severe de?ciency or absence of insulin production. Insulin therapy is essential to prevent KETOSIS – a disturbance of the body’s acid/base balance and an accumulation of ketones in the tissues. The onset is most commonly during childhood, but can occur at any age. Symptoms are acute and weight loss is common.
Non-insulin-dependent diabetes mellitus (NIDDM) (maturity-onset diabetes, type 2 diabetes) may be further sub-divided into obese and non-obese groups. This type usually occurs after the age of 40 years with an insidious onset. Subjects are often overweight and weight loss is uncommon. Ketosis rarely develops. Insulin production is reduced but not absent.
A new hormone has been identi?ed linking obesity to type 2 diabetes. Called resistin – because of its resistance to insulin – it was ?rst found in mice but has since been identi?ed in humans. Researchers in the United States believe that the hormone may, in part, explain how obesity predisposes people to diabetes. Their hypothesis is that a protein in the body’s fat cells triggers insulin resistance around the body. Other research suggests that type 2 diabetes may now be occurring in obese children; this could indicate that children should be eating a more-balanced diet and taking more exercise.
Diabetes associated with other conditions (a) Due to pancreatic disease – for example, chronic pancreatitis (see PANCREAS, DISORDERS OF); (b) secondary to drugs – for example, GLUCOCORTICOIDS (see PANCREAS, DISORDERS OF); (c) excess hormone production
– for example, growth hormone (ACROMEGALY); (d) insulin receptor abnormalities; (e) genetic syndromes (see GENETIC DISORDERS).
Gestational diabetes Diabetes occurring in pregnancy and resolving afterwards.
Aetiology Insulin-dependent diabetes occurs as a result of autoimmune destruction of beta cells within the PANCREAS. Genetic in?uences are important and individuals with certain HLA tissue types (HLA DR3 and HLA DR4) are more at risk; however, the risks associated with the HLA genes are small. If one parent has IDDM, the risk of a child developing IDDM by the age of 25 years is 1·5–2·5 per cent, and the risk of a sibling of an IDDM subject developing diabetes is about 3 per cent.
Non-insulin-dependent diabetes has no HLA association, but the genetic in?uences are much stronger. The risks of developing diabetes vary with di?erent races. Obesity, decreased exercise and ageing increase the risks of disease development. The risk of a sibling of a NIDDM subject developing NIDDM up to the age of 80 years is 30–40 per cent.
Diet Many NIDDM diabetics may be treated with diet alone. For those subjects who are overweight, weight loss is important, although often unsuccessful. A diet high in complex carbohydrate, high in ?bre, low in fat and aiming towards ideal body weight is prescribed. Subjects taking insulin need to eat at regular intervals in relation to their insulin regime and missing meals may result in hypoglycaemia, a lowering of the amount of glucose in the blood, which if untreated can be fatal (see below).
Oral hypoglycaemics are used in the treatment of non-insulin-dependent diabetes in addition to diet, when diet alone fails to control blood-sugar levels. (a) SULPHONYLUREAS act mainly by increasing the production of insulin;
(b) BIGUANIDES, of which only metformin is available, may be used alone or in addition to sulphonylureas. Metformin’s main actions are to lower the production of glucose by the liver and improve its uptake in the peripheral tissues.
Complications The risks of complications increase with duration of disease.
Diabetic hypoglycaemia occurs when amounts of glucose in the blood become low. This may occur in subjects taking sulphonylureas or insulin. Symptoms usually develop when the glucose concentration falls below 2·5 mmol/l. They may, however, occur at higher concentrations in subjects with persistent hyperglycaemia – an excess of glucose – and at lower levels in subjects with persistent hypo-glycaemia. Symptoms include confusion, hunger and sweating, with coma developing if blood-sugar concentrations remain low. Re?ned sugar followed by complex carbohydrate will return the glucose concentration to normal. If the subject is unable to swallow, glucagon may be given intramuscularly or glucose intravenously, followed by oral carbohydrate, once the subject is able to swallow.
Although it has been shown that careful control of the patient’s metabolism prevents late complications in the small blood vessels, the risk of hypoglycaemia is increased and patients need to be well motivated to keep to their dietary and treatment regime. This regime is also very expensive. All risk factors for the patient’s cardiovascular system – not simply controlling hyperglycaemia – may need to be reduced if late complications to the cardiovascular system are to be avoided.
Diabetes is one of the world’s most serious health problems. Recent projections suggest that the disorder will affect nearly 240 million individuals worldwide by 2010 – double its prevalence in 1994. The incidence of insulin-dependent diabetes is rising in young children; they will be liable to develop late complications.
Although there are complications associated with diabetes, many subjects live normal lives and survive to an old age. People with diabetes or their relatives can obtain advice from Diabetes UK (www.diabetes.org.uk).
Increased risks are present of (a) heart disease, (b) peripheral vascular disease, and (c) cerebrovascular disease.
Diabetic eye disease (a) retinopathy, (b) cataract. Regular examination of the fundus enables any abnormalities developing to be detected and treatment given when appropriate to preserve eyesight.
Nephropathy Subjects with diabetes may develop kidney damage which can result in renal failure.
Neuropathy (a) Symmetrical sensory polyneuropathy; damage to the sensory nerves that commonly presents with tingling, numbness of pain in the feet or hands. (b) Asymmetrical motor diabetic neuropathy, presenting as progressive weakness and wasting of the proximal muscles of legs. (c) Mononeuropathy; individual motor or sensory nerves may be affected. (d) Autonomic neuropathy, which affects the autonomic nervous system, has many presentations including IMPOTENCE, diarrhoea or constipation and postural HYPOTENSION.
Skin lesions There are several skin disorders associated with diabetes, including: (a) necrobiosis lipoidica diabeticorum, characterised by one or more yellow atrophic lesions on the legs;
(b) ulcers, which most commonly occur on the feet due to peripheral vascular disease, neuropathy and infection. Foot care is very important.
Diabetic ketoacidosis occurs when there is insu?cient insulin present to prevent KETONE production. This may occur before the diagnosis of IDDM or when insu?cient insulin is being given. The presence of large amounts of ketones in the urine indicates excess ketone production and treatment should be sought immediately. Coma and death may result if the condition is left untreated.
Symptoms Thirst, POLYURIA, GLYCOSURIA, weight loss despite eating, and recurrent infections (e.g. BALANITIS and infections of the VULVA) are the main symptoms.
However, subjects with non-insulindependent diabetes may have the disease for several years without symptoms, and diagnosis is often made incidentally or when presenting with a complication of the disease.
Treatment of diabetes aims to prevent symptoms, restore carbohydrate metabolism to as near normal as possible, and to minimise complications. Concentration of glucose, fructosamine and glycated haemoglobin in the blood are used to give an indication of blood-glucose control.
Insulin-dependent diabetes requires insulin for treatment. Non-insulin-dependent diabetes may be treated with diet, oral HYPOGLYCAEMIC AGENTS or insulin.
Insulin All insulin is injected – mainly by syringe but sometimes by insulin pump – because it is inactivated by gastrointestinal enzymes. There are three main types of insulin preparation: (a) short action (approximately six hours), with rapid onset; (b) intermediate action (approximately 12 hours); (c) long action, with slow onset and lasting for up to 36 hours. Human, porcine and bovine preparations are available. Much of the insulin now used is prepared by genetic engineering techniques from micro-organisms. There are many regimens of insulin treatment involving di?erent combinations of insulin; regimens vary depending on the requirements of the patients, most of whom administer the insulin themselves. Carbohydrate intake, energy expenditure and the presence of infection are important determinants of insulin requirements on a day-to-day basis.
A new treatment for diabetes, pioneered in Canada and entering its preliminary clinical trials in the UK, is the transplantation of islet cells of Langerhans from a healthy person into a patient with the disorder. If the transplantation is successful, the transplanted cells start producing insulin, thus reducing or eliminating the requirement for regular insulin injections. If successful the trials would be a signi?cant advance in the treatment of diabetes.
Scientists in Israel have developed a drug, Dia Pep 277, which stops the body’s immune system from destroying pancratic ? cells as happens in insulin-dependent diabetes. The drug, given by injection, o?ers the possibility of preventing type 1 diabetes in healthy people at genetic risk of developing the disorder, and of checking its progression in affected individuals whose ? cells are already perishing. Trials of the drug are in progress.... diabetes mellitus
Since April 1993, local social-services departments have been responsible for assessing what help people need from community-care services: these can include home helps, meals on wheels, sheltered housing, etc. Recipients of such services are means-tested and make variable contributions towards the costs. Policies on charging vary from one area to another and there are wide geographical variations in the range of services provided free and the charges levied for others.
People with complex needs may be assigned a case manager to coordinate the care package and ensure that appropriate responses are made to changing circumstances. The success of community care hinges on e?ective coordination of the services of an often large number of providers from the health and social-services sectors. Poor communication between sectors and inadequate coordination of services have been among the most common complaints about the community-care reforms.
Health care for people being cared for in the community remains largely free under the NHS arrangements, although there are regular debates about where the boundaries should be drawn between free health services and means-tested social care. A distinction has been made between necessary nursing care (funded by the state) and normal personal care (the responsibility of the patient), but the dividing line often proves hard to de?ne.
As care has shifted increasingly into the community, previous hospital facilities have become redundant. Vast numbers of beds in long-stay geriatric hospitals and in-patient psychiatric wards have been closed. There is now concern that too few beds remain to provide essential emergency and respite services. In some areas, patients ?t for discharge are kept in hospital because of delay in setting up community services for the elderly, or because of the inability of the local authority to fund appropriate care in a nursing home or at home with community-care support for other patients; the resulting BED-BLOCKING has an adverse e?ect on acutely ill patients needing hospital admission.
Community care, if correctly funded and coordinated, is an excellent way of caring for people with long-term needs, but considerable work is still needed in Britain to ensure that all patients have access to high-quality community care when they need it. Problems in providing such are are not con?ned to the UK.... community care
The power is impaired in various diseases, such as LOCOMOTOR ATAXIA. It is tested by making the patient shut their eyes, moving their hand in various directions, and then telling them to bring the point of the fore?nger steadily to the tip of the nose – or by other simple movements.... coordination
The Council is funded by doctors’ annual fees and is responsible to the Privy Council. Substantial reforms of the GMC’s structure and functions have been and are still being undertaken to ensure that it operates e?ectively in today’s rapidly evolving medical and social environment. In particular, the Council has strengthened its supervisory and disciplinary functions, and among many changes has proposed the regular revalidation of doctors’ professional abilities on a periodic basis. The Medical Register, maintained by the GMC, is intended to enable the public to identify whom it is safe to approach to obtain medical services. Entry on the Register shows that the doctor holds a recognised primary medical quali?cation and is committed to upholding the profession’s values. Under revalidation requirements being ?nalised, in addition to holding an initial quali?cation, doctors wishing to stay on the Register will have to show their continuing ?tness to practise according to the professional attributes laid down by the GMC.
Once revalidation is fully established, there will be four categories of doctor:
Those on the Register who successfully show their ?tness to practise on a regular basis.
Those whose registration is limited, suspended or removed as a result of the Council’s disciplinary procedures.
Those who do not wish to stay on the Register or retain any links with the GMC.
Those, placed on a supplementary list, who do not wish to stay on the main Register but who want to retain a formal link with the medical profession through the Council. Such doctors will not be able to practise or prescribe.... general medical council (gmc)
Hospitals are broadly divided into general hospitals (available in each district in the United Kingdom) and hospitals specialising in particular ailments (e.g. ophthalmology; ear, nose and throat; neurology, etc.). In addition there are teaching hospitals which have the dual function of patient care and the education of medical sta?. (See NATIONAL HEALTH SERVICE (NHS).)
In the UK all patients are entitled to hospital care provided by their NHS trust when referred by their GENERAL PRACTITIONER (GP) or admitted via the Accident & Emergency department. (In exceptional cases, patients with severe mental illness can be compulsorily admitted by the authorities.) Admission will depend on clinical priority, as demand commonly exceeds supply of beds in some localities. Private hospital care is available under the care of a consultant of choice, provided that the patient is covered by appropriate private medical insurance or can pay direct the substantial hospital and medical fees.
The future development of hospital medicine is controversial, but the long-term future may well see many fewer, much better equipped, highly specialised hospitals for patients requiring high-technology-based treatments. These might be backed up with a range of smaller general (or halfway) hospitals caring for patients with less demanding clinical needs who nevertheless require some bed-based care. Many more patients requiring routine specialist treatment will be treated as day patients than is the case now, and there will (or should) be much greater emphasis (with appropriate resources) on PREVENTIVE MEDICINE.
Britain is experimenting with a prototype ‘virtual hospital’. The project will target hospital patients who need to remain under the care of specialists but whose condition can be managed at home. Suitable NHS patients will be provided with monitoring equipment that enables them, for example, to read their own blood pressure, lung and heart functions, with the results transferred electronically to the o?ce of relevant specialists who will prescribe and monitor treatment.... hospital
The imaging systems of COMPUTED TOMOGRAPHY (CT) and magnetic resonance imaging (see MRI) have powerful computer techniques underlying them.
Computerised statistical analysis of study data, population databases and disease registries is now routine, leading to enhanced understanding of the interplay between diseases and the population. And the results of research, available on computerised indexes such as MEDLINE, can be obtained in searches that take only seconds, compared with the hours or days necessary to accomplish the same task with its paper incarnation, Index Medicus.
Medical informatics The direct computerisation of those activities which are uniquely medical – history-taking, examination, diagnosis and treatment – has proved an elusive goal, although one hotly pursued by doctors, engineers and scientists working in the discipline of medical informatics. Computer techniques have scored some successes: patients are, for example, more willing to be honest about taboo areas, such as their drug or alcohol consumption, or their sexual proclivities, with a computer than face to face with a clinician; however, the practice of taking a history remains the cornerstone of clinical practice. The examination of the patient is unlikely to be supplanted by technological means in the foreseeable future; visual and tactile recognition systems are still in their infancy. Skilled interpretation of the result by machine rather than the human mind seems equally as remote. Working its way slowly outwards from its starting point in mathematical logic, ARTIFICIAL INTELLIGENCE that in any way mimics its natural counterpart seems a distant prospect. Although there have been successes in computer-supported diagnosis in some specialised areas, such as the diagnosis of abdominal pain, workable systems that could supplant the mind of the generalist are still the dream of the many developers pursuing this goal, rather than a reality available to doctors in their consulting rooms now.
In therapeutics, computerised prescribing systems still require the doctor to make the decision about treatment, but facilitate the process of writing, issuing, and recording the prescription. In so doing, the system can provide automated checks, warning if necessary about allergies, potential drug interactions, or dosing errors. The built-in safety that this process o?ers is enhanced by the superior legibility of the script that ensues, reducing the potential for error when the medicine is dispensed by the nurse or the pharmacist.
Success in these individual applications continues to drive development, although the process has its critics, who are not slow to point to the lengthier consultations that arise when a computer is present in the consulting room and its distracting e?ect on communication with the patient.
Underlying these many software applications lies the ubiquitous personal computer – more powerful today than its mainframe predecessor of only 20 years ago – combined with networking technology that enables interconnection and the sharing of data. As in essence the doctor’s role involves the acquisition, manipulation and application of information – from the individual patient, and from the body of medical knowledge – great excitement surrounds the development of open systems that allow di?erent software and hardware platforms to interact. Many problems remain to be solved, not least the fact that for such systems to work, the whole organisation, and not just a few specialised individuals, must become computer literate. Such systems must be easy to learn to use, which requires an intuitive interface between user(s) and system(s) that is predictable and logical in its ordering and presentation of information.
Many other issues stand in the way of the development towards computerisation: standard systems of nomenclature for medical concepts have proved surprisingly di?cult to develop, but are crucial for successful information-sharing between users. Sharing information between existing legacy systems is a major challenge, often requiring customised software and extensive human intervention to enable the previous investments that an organisation has made in individual systems (e.g. laboratory-result reporting) to be integrated with newer technology. The beginnings of a global solution to this substantial obstacle to networking progress is in sight: the technology that enables the Internet – an international network of telephonically linked personal computers – also enables the establishment of intranets, in which individual servers (computers dedicated to serving information to other computers) act as repositories of ‘published’ data, which other users on the network may ‘browse’ as necessary in a client-server environment.
Systems that support this process are still in early stages of development, but the key conceptualisations are in place. Developments over the next 5–10 years will centre on the electronic patient record available to the clinician on an integrated clinical workstation. The clinical workstation – in essence a personal computer networked to the hospital or practice system – will enable the clinician to record clinical data and diagnoses, automate the ordering of investigations and the collection of the results, and facilitate referral and communication between the many professionals and departments involved in any individual patient’s care.
Once data is digitised – and that includes text, statistical tables, graphs, illustrations and radiological images, etc. – it may be as freely networked globally as locally. Consultations in which live video and sound transmissions are the bonds of the doctor-patient relationship (the techniques of telemedicine) are already reality, and have proved particularly convenient and cost-e?ective in linking the patient and the generalist to specialists in remote areas with low population density.
As with written personal medical records, con?dentiality of personal medical information on computers is essential. Computerised data are covered by the Data Protection Act 1984. This stipulates that data must:
be obtained and processed fairly and lawfully.
be held only for speci?ed lawful purposes.
•not be used in a manner incompatible with those purposes.
•only be recorded where necessary for these purposes.
be accurate and up to date.
not be stored longer than necessary.
be made available to the patient on request.
be protected by appropriate security and backup procedures. As these problems are solved, concerns about
privacy and con?dentiality arise. While paper records were often only con?dential by default, the potential for breaches of security in computerised networks is much graver. External breaches of the system by hackers are one serious concern, but internal breaches by authorised users making unauthorised use of the data are a much greater risk in practice. Governing network security so that clinical users have access on a need-to-know basis is a di?cult business: the software tools to enable this – encryption, and anonymisation (ensuring that clinical information about patients is anonymous to prevent con?dential information about them leaking out) of data collected for management and research processes – exist in the technical domain but remain a complex conundrum for solution in the real world.
The mushroom growth of websites covering myriad subjects has, of course, included health information. This ranges from clinical details on individual diseases to facts about medical organisations and institutes, patient support groups, etc. Some of this information contains comments and advice from orthodox and unorthodox practitioners. This open access to health information has been of great bene?t to patients and health professionals. But web browsers should be aware that not all the medical information, including suggested treatments, has been subject to PEER REVIEW, as is the case with most medical articles in recognised medical journals.... information technology in medicine
Causes The disease is directly contagious from another person already suffering from it – usually by sexual intercourse, but occasionally conveyed by the discharge on sponges, towels or clothing as well as by actual contact. The gonococcus is found in the discharge expressed from the urethra, which may be spread as a ?lm on a glass slide, suitably stained, and examined under the microscope; or a culture from the discharge may be made on certain bacteriological media and ?lms from this, similarly examined under the microscope. Since discharges resembling that of gonorrhoea accompany other forms of in?ammation, the identi?cation of the organism is of great importance. A gram-stained smear of urethral discharge enables rapid identi?cation of the gonococcus in around 90 per cent of men.
Symptoms These di?er considerably, according to whether the disease is in an acute or a chronic stage.
MEN After an incubation period of 2–10 days, irritation in the urethra, scalding pain on passing water, and a viscid yellowish-white discharge appear; the glands in the groin often enlarge and may suppurate. The urine when passed is hazy and is often found to contain yellowish threads of pus visible to the eye. After some weeks, if the condition has become chronic, the discharge is clear and viscid, there may be irritation in passing urine, and various forms of in?ammation in neighbouring organs may appear – the TESTICLE, PROSTATE GLAND and URINARY BLADDER becoming affected. At a still later stage the in?ammation of the urethra is apt to lead to gradual formation of ?brous tissue around this channel. This contracts and produces narrowing, so that urination becomes di?cult or may be stopped for a time altogether (the condition known as stricture). In?ammation of some of the joints is a common complication in the early stage – the knee, ankle, wrist, and elbow being the joints most frequently affected – and this form of ‘rheumatism’ is very intractable and liable to lead to permanent sti?ness. The ?brous tissues elsewhere may also develop in?ammatory changes, causing pain in the back, foot, etc. In occasional cases, during the acute stage, SEPTICAEMIA may develop, with in?ammation of the heart-valves (ENDOCARDITIS) and abscesses in various parts of the body. The infective matter occasionally is inoculated accidentally into the eye, producing a very severe form of conjunctivitis: in the newly born child this is known as ophthalmia neonatorum and, although now rare in the UK. has in the past been a major cause of blindness (see EYE, DISORDERS OF). WOMEN The course and complications of the disease are somewhat di?erent in women. It begins with a yellow vaginal discharge, pain on urination, and very often in?ammation or abscess of the Bartholin’s glands, situated close to the vulva or opening of the vagina. The chief seriousness, however, of the disease is due to the spread of in?ammation to neighbouring organs, the UTERUS, FALLOPIAN TUBES, and OVARIES, causing permanent destructive changes in these, and leading occasionally to PERITONITIS through the Fallopian tube with a fatal result. Many cases of prolonged ill-health and sterility or recurring miscarriages are due to these changes.
Treatment The chances of cure are better the earlier treatment is instituted. PENICILLIN is the antibiotic of choice but unfortunately the gonococcus is liable to become resistant to this. In patients who are infected with penicillin-resistant organisms, one of the other antibiotics (e.g. cefotaxime, cipro?oxacin or spectinomycin) is used. In all cases it is essential that bacteriological investigation should be carried out at weekly intervals for three or four weeks, to make sure that the patient is cured. Patients attending with gonorrhoea are asked if they will agree to tests for other sexually transmitted infections, such as HIV (see AIDS/HIV) and for assistance in contact tracing.... gonorrhoea
Interventional Radiology
The use of radiology (see X-RAYS) to enable doctors to carry out diagnostic or treatment procedures under direct radiological vision. This X-ray procedure is used in MINIMALLY INVASIVE SURGERY (MIS) – for example, ANGIOPLASTY, the removal of stones from the kidney (see KIDNEYS, DISEASES OF), and the observation of obstructions in the bile ducts (percutaneous CHOLANGIOGRAPHY). (See also magnetic resonance imaging – MRI.)... intertrigo
Pregnancy lasts about 280 days and is calculated from the ?rst day of the last menstrual period – see MENSTRUATION. Pregnancy-testing kits rely on the presence of the hormone beta HUMAN CHORIONIC GONADOTROPHIN (b HCG) which is excreted in the woman’s urine as early as 30 days from the last menstrual period. The estimated date of delivery can be accurately estimated from the size of the developing fetus measured by ULTRASOUND (see also below) between seven and 24 weeks. ‘Term’ refers to the time that the baby is due; this can range from 38 weeks to 41 completed weeks.
Physical changes occur in early pregnancy – periods stop and the abdomen enlarges. The breasts swell, with the veins becoming prominent and the nipples darkening. About two in three women will have nausea with a few experiencing such severe vomiting as to require hospital admission for rehydration.
Antenatal care The aim of antenatal care is to ensure a safe outcome for both mother and child; it is provided by midwives (see MIDWIFE) and doctors. Formal antenatal care began in Edinburgh in the 1930s with the recognition that all aspects of pregnancy – normal and abnormal – warranted surveillance. Cooperation between general practitioners, midwives and obstetricians is now established, with pregnancies that are likely to progress normally being cared for in the community and only those needing special intervention being cared for in a hospital setting.
The initial visit (or booking) in the ?rst half of pregnancy will record the history of past events and the results of tests, with the aim of categorising the patients into normal or not. Screening tests including blood checks and ultrasound scans are a routine part of antenatal care. The ?rst ultrasound scan is done at about 11 weeks to date the pregnancy, with a further one done at 20 weeks – the anomaly scan – to assess the baby’s structure. Some obstetric units will check the growth of the baby with one further scan later in the pregnancy or, in the case of twin pregnancies (see below), many scans throughout. The routine blood tests include checks for ANAEMIA, DIABETES MELLITUS, sickle-cell disease and THALASSAEMIA, as well as for the blood group. Evidence of past infections is also looked for; tests for RUBELLA (German measles) and SYPHILIS are routine, whereas tests for human immunode?ciency virus (see AIDS/ HIV below) and HEPATITIS are being o?ered as optional, although there is compelling evidence that knowledge of the mother’s infection status is bene?cial to the baby.
Traditional antenatal care consists of regular appointments, initially every four weeks until 34 weeks, then fortnightly or weekly. At each visit the mother’s weight, urine and blood pressure are checked, and assessment of fetal growth and position is done by palpating the uterus. Around two-thirds of pregnancies and labours are normal: in the remainder, doctors and midwives need to increase the frequency of surveillance so as to prevent or deal with maternal and fetal problems.
Common complications of pregnancy
Some of the more common complications of pregnancy are listed below.
As well as early detection of medical complications, antenatal visits aim to be supportive and include emotional and educational care. Women with uncomplicated pregnancies are increasingly being managed by midwives and general practitioners in the community and only coming to the hospital doctors should they develop a problem. A small number will opt for a home delivery, but facilities for providing such a service are not always available in the UK.
Women requiring more intensive surveillance have their management targeted to the speci?c problems encountered. Cardiologists will see mothers-to-be with heart conditions, and those at risk of diabetes are cared for in designated clinics with specialist sta?. Those women needing more frequent surveillance than standard antenatal care can be looked after in maternity day centres. These typically include women with mildly raised blood pressure or those with small babies. Fetal medicine units have specialists who are highly skilled in ultrasound scanning and specialise in the diagnosis and management of abnormal babies still in the uterus. ECTOPIC PREGNANCY Chronic abdominal discomfort early in pregnancy may be caused by unruptured ectopic pregnancy, when, rarely, the fertilised OVUM starts developing in the Fallopian tube (see FALLOPIAN TUBES) instead of the uterus. The patient needs hospital treatment and LAPAROSCOPY. A ruptured ectopic pregnancy causes acute abdominal symptoms and collapse, and the woman will require urgent abdominal surgery. URINARY TRACT INFECTIONS These affect around 2 per cent of pregnant women and are detected by a laboratory test of a mid-stream specimen of urine. In pregnancy, symptoms of these infections do not necessarily resemble those experienced by non-pregnant women. As they can cause uterine irritability and possible premature labour (see below), it is important to ?nd and treat them appropriately. ANAEMIA is more prevalent in patients who are vegetarian or on a poor diet. Iron supplements are usually given to women who have low concentrations of HAEMOGLOBIN in their blood (less than 10.5 g/dl) or who are at risk of becoming low in iron, from bleeding, twin pregnancies and those with placenta previa (see below). ANTEPARTUM HAEMORRHAGE Early in pregnancy, vaginal bleedings may be due to a spontaneous or an incomplete therapeutic ABORTION. Bleeding from the genital tract between 24 completed weeks of pregnancy and the start of labour is called antepartum haemorrhage. The most common site is where the PLACENTA is attached to the wall of the uterus. If the placenta separates before delivery, bleeding occurs in the exposed ‘bed’. When the placenta is positioned in the upper part of the uterus it is called an abruption. PLACENTA PRAEVIA is sited in the lower part and blocks or partly blocks the cervix (neck of the womb); it can be identi?ed at about the 34th week. Ten per cent of episodes of antepartum bleeding are caused by placenta previa, and it may be associated with bleeding at delivery. This potentially serious complication is diagnosed by ultrasound scanning and may require a caesarean section (see below) at delivery. INCREASED BLOOD PRESSURE, associated with protein in the urine and swelling of the limbs, is part of a condition known as PRE-ECLAMPSIA. This occurs in the second half of pregnancy in about 1 in 10 women expecting their ?rst baby, and is mostly very mild and of no consequence to the pregnancy. However, some women can develop extremely high blood pressures which can adversely affect the fetus and cause epileptic-type seizures and bleeding disorders in the mother. This serious condition is called ECLAMPSIA. For this reason a pregnant woman with raised blood pressure or PROTEIN in her urine is carefully evaluated with blood tests, often in the maternity day assessment unit. The condition can be stopped by delivery of the baby, and this will be done if the mother’s or the fetus’s life is in danger. If the condition is milder, and the baby not mature enough for a safe delivery, then drugs can be used to control the blood pressure. MISCARRIAGE Also called spontaneous abortion, miscarriage is the loss of the fetus. There are several types:
threatened miscarriage is one in which some vaginal bleeding occurs, the uterus is enlarged, but the cervix remains closed and pregnancy usually proceeds.
inevitable miscarriage usually occurs before the 16th week and is typi?ed by extensive blood loss through an opened cervix and cramp-like abdominal pain; some products of conception are lost but the developing placental area (decidua) is retained and an operation may be necessary to clear the womb.
missed miscarriages, in which the embryo dies and is absorbed, but the decidua (placental area of uterine wall) remains and may cause abdominal discomfort and discharge of old blood.
THERAPEUTIC ABORTION is performed on more than 170,000 women annually in England and Wales. Sometimes the woman may not have arranged the procedure through the usual health-care channels, so that a doctor may see a patient with vaginal bleeding, abdominal discomfort or pain, and open cervix – symptoms which suggest that the decidua and a blood clot have been retained; these retained products will need to be removed by curettage.
Septic abortions are now much less common in Britain than before the Abortion Act (1967) permitted abortion in speci?ed circumstances. The cause is the passage of infective organisms from the vagina into the uterus, with Escherichia coli and Streptococcus faecalis the most common pathogenic agents. The woman has abdominal pain, heavy bleeding, usually fever and sometimes she is in shock. The cause is usually an incomplete abortion or one induced in unsterile circumstances. Antibiotics and curettage are the treatment. INTRAUTERINE GROWTH RETARDATION describes a slowing of the baby’s growth. This can be diagnosed by ultrasound scanning, although there is a considerable margin of error in estimates of fetal weight. Trends in growth are favoured over one-o? scan results alone. GESTATIONAL DIABETES is a condition that is more common in women who are overweight or have a family member with diabetes. If high concentrations of blood sugar are found, e?orts are made to correct it as the babies can become very fat (macrosomia), making delivery more di?cult. A low-sugar diet is usually enough to control the blood concentration of sugars; however some women need small doses of INSULIN to achieve control. FETAL ABNORMALITIES can be detected before birth using ultrasound. Some of these defects are obvious, such as the absence of kidneys, a condition incompatible with life outside the womb. These women can be o?ered a termination of their pregnancy. However, more commonly, the pattern of problems can only hint at an abnormality and closer examination is needed, particularly in the diagnosis of chromosomal deformities such as DOWN’S (DOWN) SYNDROME (trisomy 21 or presence of three 21 chromosomes instead of two).
Chromosomal abnormalities can be de?nitively diagnosed only by cell sampling such as amniocentesis (obtaining amniotic ?uid – see AMNION – from around the baby) done at 15 weeks onwards, and chorionic villus sampling (sampling a small part of the placenta) – another technique which can be done from 12 weeks onwards. Both have a small risk of miscarriage associated with them; consequently, they are con?ned to women at higher risk of having an abnormal fetus.
Biochemical markers present in the pregnant woman’s blood at di?erent stages of pregnancy may have undergone changes in those carrying an abnormal fetus. The ?rst such marker to be routinely used was a high concentration of alpha-fetol protein in babies with SPINA BIFIDA (defects in the covering of the spinal cord). Fuller research has identi?ed a range of diagnostic markers which are useful, and, in conjunction with other factors such as age, ethnic group and ultrasound ?ndings, can provide a predictive guide to the obstetrician – in consultation with the woman – as to whether or not to proceed to an invasive test. These tests include pregnancy-associated plasma protein assessed from a blood sample taken at 12 weeks and four blood tests at 15–22 weeks – alphafetol protein, beta human chorionic gonadotrophin, unconjugated oestriol and inhibin A. Ultrasound itself can reveal physical ?ndings in the fetus, which can be more common in certain abnormalities. Swelling in the neck region of an embryo in early pregnancy (increased nuchal thickness) has good predictive value on its own, although its accuracy is improved in combination with the biochemical markers. The e?ectiveness of prenatal diagnosis is rapidly evolving, the aim being to make the diagnosis as early in the pregnancy as possible to help the parents make more informed choices. MULTIPLE PREGNANCIES In the UK, one in 95 deliveries is of twins, while the prevalence of triplets is one in 10,000 and quadruplets around one in 500,000. Racial variations occur, with African women having a prevalence rate of one in 30 deliveries for twins and Japanese women a much lower rate than the UK ?gure. Multiple pregnancies occur more often in older women, and in the UK the prevalence of fertility treatments, many of these being given to older women, has raised the incidence. There is now an o?cial limit of three eggs being transferred to a woman undergoing ASSISTED CONCEPTION (gamete intrafallopian transfer, or GIFT).
Multiple pregnancies are now usually diagnosed as a result of routine ultrasound scans between 16 and 20 weeks of pregnancy. The increased size of the uterus results in the mother having more or worse pregnancy-related conditions such as nausea, abdominal discomfort, backache and varicose veins. Some congenital abnormalities in the fetus occur more frequently in twins: NEURAL TUBE defects, abnormalities of the heart and the incidence of TURNER’S SYNDROME and KLINEFELTER’S SYNDROME are examples. Such abnormalities may be detected by ultrasound scans or amniocentesis. High maternal blood pressure and anaemia are commoner in women with multiple pregnancies (see above).
The growth rates of multiple fetuses vary, but the di?erence between them and single fetuses are not that great until the later stages of pregnancy. Preterm labour is commoner in multiple pregnancies: the median length of pregnancy is 40 weeks for singletons, 37 for twins and 33 for triplets. Low birth-weights are usually the result of early delivery rather than abnormalities in growth rates. Women with multiple pregnancies require more frequent and vigilant antenatal assessments, with their carers being alert to the signs of preterm labour occurring. CEPHALOPELVIC DISPROPORTION Disparity between the size of the fetus and the mother’s pelvis is not common in the UK but is a signi?cant problem in the developing world. Disparity is classi?ed as absolute, when there is no possibility of delivery, and relative, when the baby is large but delivery (usually after a dif?cult labour) is possible. Causes of absolute disparity include: a large baby – heavier than 5 kg at birth; fetal HYDROCEPHALUS; and an abnormal maternal pelvis. The latter may be congenital, the result of trauma or a contraction in pelvic size because of OSTEOMALACIA early in life. Disproportion should be suspected if in late pregnancy the fetal head has not ‘engaged’ in the pelvis. Sometimes a closely supervised ‘trial of labour’ may result in a successful, if prolonged, delivery. Otherwise a caesarean section (see below) is necessary. UNUSUAL POSITIONS AND PRESENTATIONS OF THE BABY In most pregnant women the baby ?ts into the maternal pelvis head-?rst in what is called the occipito-anterior position, with the baby’s face pointing towards the back of the pelvis. Sometimes, however, the head may face the other way, or enter the pelvis transversely – or, rarely, the baby’s neck is ?exed backwards with the brow or face presenting to the neck of the womb. Some malpositions will correct naturally; others can be manipulated abdominally during pregnancy to a better position. If, however, the mother starts labour with the baby’s head badly positioned or with the buttocks instead of the head presenting (breech position), the labour will usually be longer and more di?cult and may require intervention using special obstetric forceps to assist in extracting the baby. If progress is poor and the fetus distressed, caesarean section may be necessary. HIV INFECTION Pregnant women who are HIV positive (see HIV; AIDS/HIV) should be taking antiviral drugs in the ?nal four to ?ve months of pregnancy, so as to reduce the risk of infecting the baby in utero and during birth by around 50 per cent. Additional antiviral treatment is given before delivery; the infection risk to the baby can be further reduced – by about 40 per cent – if delivery is by caesarean section. The mother may prefer to have the baby normally, in which case great care should be taken not to damage the baby’s skin during delivery. The infection risk to the baby is even further reduced if it is not breast fed. If all preventive precautions are taken, the overall risk of the infant becoming infected is cut to under 5 per cent.
Premature birth This is a birth that takes place before the end of the normal period of gestation, usually before 37 weeks. In practice, however, it is de?ned as a birth that takes place when the baby weighs less than 2·5 kilograms (5••• pounds). Between 5 and 10 per cent of babies are born prematurely, and in around 40 per cent of premature births the cause is unknown. Pre-eclampsia is the most common known cause; others include hypertension, chronic kidney disease, heart disease and diabetes mellitus. Multiple pregnancy is another cause. In the vast majority of cases the aim of management is to prolong the pregnancy and so improve the outlook for the unborn child. This consists essentially of rest in bed and sedation, but there are now several drugs, such as RITODRINE, that may be used to suppress the activity of the uterus and so help to delay premature labour. Prematurity was once a prime cause of infant mortality but modern medical care has greatly improved survival rates in developing countries.
Labour Also known by the traditional terms parturition, childbirth or delivery, this is the process by which the baby and subsequently the placenta are expelled from the mother’s body. The onset of labour is often preceded by a ‘show’ – the loss of the mucus and blood plug from the cervix, or neck of the womb; this passes down the vagina to the exterior. The time before the beginning of labour is called the ‘latent phase’ and characteristically lasts 24 hours or more in a ?rst pregnancy. Labour itself is de?ned by regular, painful contractions which cause dilation of the neck of the womb and descent of the fetal head. ‘Breaking of the waters’ is the loss of amniotic ?uid vaginally and can occur any time in the delivery process.
Labour itself is divided into three stages: the ?rst is from the onset of labour to full (10 cm) dilation of the neck of the womb. This stage varies in length, ideally taking no more than one hour per centimetre of dilation. Progress is monitored by regular vaginal examinations, usually every four hours. Fetal well-being is observed by intermittent or continuous monitoring of the fetal heart rate in relation to the timing and frequency of the contractions. The print-out is called a cardiotocograph. Abnormalities of the fetal heart rate may suggest fetal distress and may warrant intervention. In women having their ?rst baby (primigravidae), the common cause of a slow labour is uncoordinated contractions which can be overcome by giving either of the drugs PROSTAGLANDIN or OXYTOCIN, which provoke contractions of the uterine muscle, by an intravenous drip. Labours which progress slowly or not at all may be due to abnormal positioning of the fetus or too large a fetus, when prostaglandin or oxytocin is used much more cautiously.
The second stage of labour is from full cervical dilation to the delivery of the baby. At this stage the mother often experiences an irresistible urge to push the baby out, and a combination of strong coordinated uterine contractions and maternal e?ort gradually moves the baby down the birth canal. This stage usually lasts under an hour but can take longer. Delay, exhaustion of the mother or distress of the fetus may necessitate intervention by the midwife or doctor. This may mean enlarging the vaginal opening with an EPISIOTOMY (cutting of the perineal outlet – see below) or assisting the delivery with specially designed obstetric forceps or a vacuum extractor (ventouse). If the cervix is not completely dilated or open and the head not descended, then an emergency caesarean section may need to be done to deliver the baby. This procedure involves delivering the baby and placenta through an incision in the mother’s abdomen. It is sometimes necessary to deliver by planned or elective caesarean section: for example, if the placenta is low in the uterus – called placenta praevia – making a vaginal delivery dangerous.
The third stage occurs when the placenta (or afterbirth) is delivered, which is usually about 10–20 minutes after the baby. An injection of ergometrine and oxytocin is often given to women to prevent bleeding.
Pain relief in labour varies according to the mother’s needs. For uncomplicated labours, massage, reassurance by a birth attendant, and a warm bath and mobilisation may be enough for some women. However, some labours are painful, particularly if the woman is tired or anxious or is having her ?rst baby. In these cases other forms of analgesia are available, ranging from inhalation of NITROUS OXIDE GAS, injection of PETHIDINE HYDROCHLORIDE or similar narcotic, and regional local anaesthetic (see ANAESTHESIA).
Once a woman has delivered, care continues to ensure her and the baby’s safety. The midwives are involved in checking that the uterus returns to its normal size and that there is no infection or heavy bleeding, as well as caring for stitches if needed. The normal blood loss after birth is called lochia and generally is light, lasting up to six weeks. Midwives o?er support with breast feeding and care of the infant and will visit the parents at home routinely for up to two weeks.
Some complications of labour All operative deliveries in the UK are now done in hospitals, and are performed if a spontaneous birth is expected to pose a bigger risk to the mother or her child than a specialist-assisted one. Operative deliveries include caesarean section, forceps-assisted deliveries and those in which vacuum extraction (ventouse) is used. CAESAREAN SECTION Absolute indications for this procedure, which is used to deliver over 15 per cent of babies in Britain, are cephalopelvic disproportion and extensive placenta praevia, both discussed above. Otherwise the decision to undertake caesarean section depends on the clinical judgement of the specialist and the views of the mother. The rise in the proportion of this type of intervention (from 5 per cent in the 1930s to its present level of over 23 per cent
P
of the 600,000 or so annual deliveries in England) has been put down to defensive medicine
– namely, the doctor’s fear of litigation (initiated often because the parents believe that the baby’s health has suffered because the mother had an avoidably di?cult ‘natural’ labour). In Britain, over 60 per cent of women who have had a caesarean section try a vaginal delivery in a succeeding pregnancy, with about two-thirds of these being successful. Indications for the operation include:
absolute and relative cephalopelvic disproportion.
placenta previa.
fetal distress.
prolapsed umbilical cord – this endangers the viability of the fetus because the vital supply of oxygen and nutrients is interrupted.
malpresentation of the fetus such as breech or transverse lie in the womb.
unsatisfactory previous pregnancies or deliveries.
a request from the mother.
Caesarean sections are usually performed using regional block anaesthesia induced by a spinal or epidural injection. This results in loss of feeling in the lower part of the body; the mother is conscious and the baby not exposed to potential risks from volatile anaesthetic gases inhaled by the mother during general anaesthesia. Post-operative complications are higher with general anaesthesia, but maternal anxiety and the likelihood that the operation might be complicated and di?cult are indications for using it. A general anaesthetic may also be required for an acute obstetric emergency. At operation the mother’s lower abdomen is opened and then her uterus opened slowly with a transverse incision and the baby carefully extracted. A transverse incision is used in preference to the traditional vertical one as it enables the woman to have a vaginal delivery in any future pregnancy with a much smaller risk of uterine rupture. Women are usually allowed to get up within 24 hours and are discharged after four or ?ve days. FORCEPS AND VENTOUSE DELIVERIES Obstetric forceps are made in several forms, but all are basically a pair of curved blades shaped so that they can obtain a purchase on the baby’s head, thus enabling the operator to apply traction and (usually) speed up delivery. (Sometimes they are used to slow down progress of the head.) A ventouse or vacuum extractor comprises an egg-cup-shaped metal or plastic head, ranging from 40 to 60 mm in diameter with a hollow tube attached through which air is extracted by a foot-operated vacuum pump. The instrument is placed on the descending head, creating a negative pressure on the skin of the scalp and enabling the operator to pull the head down. In mainland Europe, vacuum extraction is generally preferred to forceps for assisting natural deliveries, being used in around 5 per cent of all deliveries. Forceps have a greater risk of causing damage to the baby’s scalp and brain than vacuum extraction, although properly used, both types should not cause any serious damage to the baby.
Episiotomy Normal and assisted deliveries put the tissues of the genital tract under strain. The PERINEUM is less elastic than the vagina and, if it seems to be splitting as the baby’s head
moves down the birth canal, it may be necessary to cut the perineal tissue – a procedure called an episiotomy – to limit damage. This is a simple operation done under local anaesthetic. It should be done only if there is a speci?c indication; these include:
to hasten the second stage of labour if the fetus is distressed.
to facilitate the use of forceps or vacuum extractor.
to enlarge a perineum that is restricted because of unyielding tissue, perhaps because of a scar from a previous labour. Midwives as well as obstetricians are trained
to undertake and repair (with sutures) episiotomies.
(For organisations which o?er advice and information on various aspects of childbirth, including eclampsia, breast feeding and multiple births, see APPENDIX 2: ADDRESSES: SOURCES OF INFORMATION, ADVICE, SUPPORT AND SELF-HELP.)... pregnancy and labour
Viral infections by any of hepatitis A, B, C, D, or E viruses and also CYTOMEGALOVIRUS (CMV), EPSTEIN BARR VIRUS, and HERPES SIMPLEX.
Autoimmune disorders such as autoimmune chronic hepatitis, toxins, alcohol and certain drugs – ISONIAZID, RIFAMPICIN, HALOTHANE and CHLORPROMAZINE.
WILSON’S DISEASE.
Acute viral hepatitis causes damage throughout the liver and in severe infections may destroy whole lobules (see below).
Chronic hepatitis is typi?ed by an invasion of the portal tract by white blood cells (mild hepatitis). If these mononuclear in?ammatory cells invade the body (parenchyma) of the liver tissue, ?brosis and then chronic disease or cirrhosis can develop. Cirrhosis may develop at any age and commonly results in prolonged ill health. It is an important cause of premature death, with excessive alcohol consumption commonly the triggering factor. Sometimes, cirrhosis may be asymptomatic, but common symptoms are weakness, tiredness, poor appetite, weight loss, nausea, vomiting, abdominal discomfort and production of abnormal amounts of wind. Initially, the liver may enlarge, but later it becomes hard and shrunken, though rarely causing pain. Skin pigmentation may occur along with jaundice, the result of failure to excrete the liver product BILIRUBIN. Routine liver-function tests on blood are used to help diagnose the disease and to monitor its progress. Spider telangiectasia (caused by damage to blood vessels – see TELANGIECTASIS) usually develop, and these are a signi?cant pointer to liver disease. ENDOCRINE changes occur, especially in men, who lose their typical hair distribution and suffer from atrophy of their testicles. Bruising and nosebleeds occur increasingly as the cirrhosis worsens, and portal hypertension (high pressure of venous blood circulation through the liver) develops due to abnormal vascular resistance. ASCITES and HEPATIC ENCEPHALOPATHY are indications of advanced cirrhosis.
Treatment of cirrhosis is to tackle the underlying cause, to maintain the patient’s nutrition (advising him or her to avoid alcohol), and to treat any complications. The disorder can also be treated by liver transplantation; indeed, 75 per cent of liver transplants are done for cirrhosis. The overall prognosis of cirrhosis, however, is not good, especially as many patients attend for medical care late in the course of the disease. Overall, only 25 per cent of patients live for ?ve years after diagnosis, though patients who have a liver transplant and survive for a year (80 per cent do) have a good prognosis.
Autoimmune hepatitis is a type that most commonly occurs in women between 20 and 40 years of age. The cause is unknown and it has been suggested that the disease has several immunological subtypes. Symptoms are similar to other viral hepatitis infections, with painful joints and AMENORRHOEA as additional symptoms. Jaundice and signs of chronic liver disease usually occur. Treatment with CORTICOSTEROIDS is life-saving in autoimmune hepatitis, and maintenance treatment may be needed for two years or more. Remissions and exacerbations are typical, and most patients eventually develop cirrhosis, with 50 per cent of victims dying of liver failure if not treated. This ?gure falls to 10 per cent in treated patients.
Viral hepatitis The ?ve hepatic viruses (A to E) all cause acute primary liver disease, though each belongs to a separate group of viruses.
•Hepatitis A virus (HAV) is an ENTEROVIRUS
which is very infectious, spreading by faecal contamination from patients suffering from (or incubating) the infection; victims excrete viruses into the faeces for around ?ve weeks during incubation and development of the disease. Overcrowding and poor sanitation help to spread hepatitis A, which fortunately usually causes only mild disease.
Hepatitis B (HBV) is caused by a hepadna virus, and humans are the only reservoir of infection, with blood the main agent for transferring it. Transfusions of infected blood or blood products, and injections using contaminated needles (common among habitual drug abusers), are common modes of transfer. Tattooing and ACUPUNCTURE may spread hepatitis B unless high standards of sterilisation are maintained. Sexual intercourse, particularly between male homosexuals, is a signi?cant infection route.
Hepatitis C (HCV) is a ?avivirus whose source of infection is usually via blood contacts. E?ective screening of blood donors and heat treatment of blood factors should prevent the spread of this infection, which becomes chronic in about 75 per cent of those infected, lasting for life. Although most carriers do not suffer an acute illness, they must practise life-long preventive measures.
Hepatitis D (HDV) cannot survive independently, needing HBV to replicate, so its sources and methods of spread are similar to the B virus. HDV can infect people at the same time as HBV, but it is capable of superinfecting those who are already chronic carriers of the B virus. Acute and chronic infection of HDV can occur, depending on individual circumstances, and parenteral drug abuse spreads the infection. The disease occurs worldwide, being endemic in Africa, South America and the Mediterranean littoral.
Hepatitis E virus (HEV) is excreted in the stools, spreading via the faeco-oral route. It causes large epidemics of water-borne hepatitis and ?ourishes wherever there is poor sanitation. It resembles acute HAV infection and the patient usually recovers. HEV does not cause chronic infection. The clinical characteristics of the ?ve hepatic
viruses are broadly similar. The initial symptoms last for up to two weeks (comprising temperature, headache and malaise), and JAUNDICE then develops, with anorexia, nausea, vomiting and diarrhoea common manifestations. Upper abdominal pain and a tender enlarged liver margin, accompanied by enlarged cervical lymph glands, are usual.
As well as blood tests to assess liver function, there are speci?c virological tests to identify the ?ve infective agents, and these are important contributions to diagnosis. However, there is no speci?c treatment of any of these infections. The more seriously ill patients may require hospital care, mainly to enable doctors to spot at an early stage those developing acute liver failure. If vomiting is a problem, intravenous ?uid and glucose can be given. Therapeutic drugs – especially sedatives and hypnotics – should be avoided, and alcohol must not be taken during the acute phase. Interferon is the only licensed drug for the treatment of chronic hepatitis B, but this is used with care.
Otherwise-?t patients under 40 with acute viral hepatitis have a mortality rate of around
0.5 per cent; for those over 60, this ?gure is around 3 per cent. Up to 95 per cent of adults with acute HBV infection recover fully but the rest may develop life-long chronic hepatitis, particularly those who are immunode?cient (see IMMUNODEFICIENCY).
Infection is best prevented by good living conditions. HVA and HVB can be prevented by active immunisation with vaccines. There is no vaccine available for viruses C, D and E, although HDV is e?ectively prevented by immunisation against HBV. At-risk groups who should be vaccinated against HBV include:
Parenteral drug abusers.
Close contacts of infected individuals such as regular sexual partners and infants of infected mothers.
Men who have sex with men.
Patients undergoing regular haemodialysis.
Selected health professionals, including laboratory sta? dealing with blood samples and products.... hepatitis
Blood pressure is measured using two values. The systolic pressure – the greater of the two – represents the pressure when blood is pumped from the left VENTRICLE of the heart into the AORTA. The diastolic pressure is the measurement when both ventricles relax between beats. The pressures are measured in millimetres (mm) of mercury (Hg). Despite the grey area between normal and raised blood pressure, the World Health Organisation (WHO) has de?ned hypertension as a blood pressure consistently greater than 160 mm Hg (systolic) and 95 mm Hg (diastolic). Young children have readings well below these, but blood pressure rises with age and a healthy person may well live symptom free with a systolic pressure above the WHO ?gure. A useful working de?nition of hypertension is the ?gure at which the bene?ts of treating the condition outweigh the risks and costs of the treatment.
Between 10 and 20 per cent of the adult population in the UK has hypertension, with more men than women affected. Incidence is highest in the middle-aged and elderly. Because most people with hypertension are symptomless, the condition is often ?rst identi?ed during a routine medical examination, otherwise a diagnosis is usually made when complications occur. Many people’s blood pressure rises when they are anxious or after exercise, so if someone’s pressure is above normal at the ?rst testing, it should be taken again after, say, 10 minutes’ rest, by which time the reading should have settled to the person’s regular level. BP measurements should then be taken on two subsequent occasions. If the pressure is still high, the cause needs to be determined: this is done using a combination of personal and family histories (hypertension can run in families), a physical examination and investigations, including an ECG and blood tests for renal disease.
Over 90 per cent of hypertensive people have no immediately identi?able cause for their condition. They are described as having essential hypertension. In those patients with an identi?able cause, the hypertension is described as secondary. Among the causes of secondary hypertension are:
Lifestyle factors such as smoking, alcohol, stress, excessive dietary salt and obesity.
Diseases of the KIDNEYS.
Pregnancy (ECLAMPSIA).
Various ENDOCRINE disorders – for example, PHAEOCHROMOCYTOMA, CUSHING’S DISEASE, ACROMEGALY, thyrotoxicosis (see under THYROID GLAND, DISEASES OF).
COARCTATION OF THE AORTA.
Drugs – for example, oestrogen-containing oral contraceptives (see under CONTRACEPTION), ANABOLIC STEROIDS, CORTICOSTEROIDS, NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).
Treatment People with severe hypertension may need prompt admission to hospital for urgent investigation and treatment. Those with a mild to moderate rise in blood pressure for which no cause is identi?able should be advised to change their lifestyle: smokers should stop the habit, and those with high alcohol consumption should greatly reduce or stop their drinking. Obese people should reduce their food consumption, especially of animal fats, and take more exercise. Everyone with hypertension should follow a low-salt diet and take regular exercise. Patients should also be taught how to relax, which helps to reduce blood pressure and, if they have a stressful life, working patterns should be modi?ed if possible. If these lifestyle changes do not reduce a person’s blood pressure su?ciently, drugs to achieve this will be needed. A wide range of anti-hypertensive drugs are available on prescription.
A ?rst-line treatment is one of the THIAZIDES, e?ective at a low dosage and especially useful in the elderly. Beta blockers (see BETAADRENOCEPTOR-BLOCKING DRUGS), such as oxprenolol, acebutol or atenolol, are also ?rst-line treatments. ACE inhibitors (see ANGIOTENSIN-CONVERTING ENZYME (ACE) INHIBITORS) and CALCIUM-CHANNEL BLOCKERS can be used if the ?rst-line choices are not e?ective. The drug treatment of hypertension is complex, and sometimes various drugs or combinations of drugs have to be tried to ?nd what regimen is e?ective and suits the patient. Mild to moderate hypertension can usually be treated in general practice, but patients who do not respond or have complications will normally require specialist advice. Patients on anti-hypertensive treatments require regular monitoring, and, as treatment may be necessary for several years, particular attention should be paid to identifying sideeffects. Nevertheless, e?ective treatment of hypertension does enable affected individuals to live longer and more comfortable lives than would otherwise be the case. Older people with moderately raised blood pressure are often able to live with the condition, and treatment with anti-hypertensive drugs may produce symptoms of HYPOTENSION.
In summary, hypertension is a complex disorder, with di?erent patients responding di?erently to treatment. So the condition sometimes requires careful assessment before the most e?ective therapy for a particular individual is identi?ed, and continued monitoring of patients with the disorder is advisable.
Complications Untreated hypertension may eventually result in serious complications. People with high blood pressure have blood vessels with thickened, less ?exible walls, a narrowed LUMEN and convoluted shape. Sometimes arteries become rigid. ANEURYSM may develop and widespread ATHEROMA (fat deposits) is apparent in the arterial linings. Such changes adversely affect the blood supply to body tissues and organs and so damage their functioning. Patients suffer STROKE (haemorrhage from or thrombosis in the arteries of the BRAIN) and heart attacks (coronary thrombosis
– see HEART, DISEASES OF). Those with hypertension may suffer damage to the retina of the EYE and to the OPTIC DISC. Indeed, the diagnosis of hypertension is sometimes made during a routine eye test, when the doctor or optician notices changes in the retinal arteries or optic disc. Kidney function is often affected, with patients excreting protein and excessive salt in their urine. Occasionally someone with persistent hypertension may suffer an acceleration of damage to the blood vessels – a condition described as ‘malignant’ hypertension, and one requiring urgent hospital treatment.
Hypertension is a potentially dangerous disease because it develops into a cycle of self-perpetuating damage. Faulty blood vessels lead to high blood pressure which in turn aggravates the damage in the vessels and thus in the tissues and organs they supply with blood; this further raises the affected individual’s blood pressure and the pathological cycle continues.... hypertension
Applications of radionuclides to diagnosis The use of radionuclides in diagnosis is based on the fact that it is possible to tag many of the substances normally present in the body with a radioactive label. Certain synthetic radioactive elements, such as technetium, can also be used. Because it is possible to detect minute quantities of radioactive material, only very small doses are needed, making the procedure a safe one. Furthermore the body pool of the material is therefore not appreciably altered, and metabolism is not disturbed. Thus in studies of iodine metabolism the ratio of radioactive atoms administered to stable atoms in the body pool is of the order of 1:1,000 million. By measuring radioactivity in the body, in blood samples, or in the excreta it is possible to gain information about the fate of the labelled substance, and hence of the chemically identical inactive material. Therefore it is theoretically possible to trace the absorption, distribution and excretion of any substance normally present in the body, provided that it can be tagged with a suitable radioactive label.
If the investigation necessitates tracing the path of the material through the body by means of external counting over the body surface, it is obviously essential to use an isotope that emits gamma radiation or positrons. If, however, only measurements on blood sample or excreta are required, it is possible to use pure beta emitters. Whole-body counters measure the total radioactivity in the body, and these are of great value in absorption studies.
Moving images can provide information on body functions such as the movements of the heart, blood ?ow, bile ?ow in the liver, and urine in the kidneys. The development of COMPUTED TOMOGRAPHY or CT scanning has replaced radionuclide scanning for some imaging procedures.
Five main groups of diagnostic uses may be de?ned:
(1) METABOLIC STUDIES The use of radioactive materials in metabolic studies is based on the fundamental property that all isotopes of an element are chemically identical. The radioactive isotope is used as a true isotope tracer – that is, when introduced into the body (in whatever form) it behaves in the same way as the inactive element. For example, isotopes of iodine are used to measure thyroid function (see THYROID GLAND), and isotopes of calcium enable kinetic studies of bone formation and destruction to be performed.... isotope
Habitat: United States of America.
Features ? Flower supposed to resemble a lady's shoe in form. Rhizome about quarter- inch diameter, many cupshaped scars on top surface; wavy, thickly-matted roots underneath. Fracture short and white.Part used ? Rhizome.Action: Antispasmodic, tonic, nervine.
Combined with other tonics in the relief of neuralgia, and to allay paingenerally. Of use in hysteria and other nervous disorders. Dose, 1 drachm of the powdered rhizome. Like other medicines of a similar nature, it is of little use unless the cause of the nervous excitement is traced and removed.The remarks of Rafinesque, then Professor of Medical Botany in the University of Transylvania, are interesting in view of the "orthodox" attitude towards remedies of the herbalists ? "I am enabled to introduce, for the first time, this beautiful genus into our materia medica ; all the species are equally remedial. They have long been known to the Indians, who called them moccasin flower, and were used by the empyrics of New England, particularly Samuel Thomson. Their properties, however, have been tested and confirmed by Dr. Hales, of Troy; Dr. Tully, of Albany, etc.. . . They produce beneficial effects in all nervous diseases and hysterical affections by allaying pain, quieting the nerves and promoting sleep. They are preferable to opium in many cases, having no baneful or narcotic effect."Professor Rafinesque, however, goes even further than would Thomson and his successors when he announces that "all the species are equally remedial."... ladies' slipperCentral to an understanding of public health is recognition that public-health practitioners are concerned not just with individuals, but also with whole populations – and that improving health care plays only a part of public-health improvement. The health of populations (public health) is also dependent on many factors such as the social, economic and physical environment in which the people live and the nutrition and health care available to them.
For thousands of years, a fundamental feature of civilisations has been to seek to improve the health of the population and protect it from disease. This has led to the development of legal frameworks which di?er widely from country to country, depending on their social and political development. All are concerned to stop the spread of infectious diseases, and to maintain the safety of urban food and water supplies and waste disposal. Most are also associated with housing standards, some form of poverty relief, and basic health care. Some trading standards are often covered, at least in relation to the sale and distribution of poisons and drugs, and to controls on industrial and transport safety – for example, in relation to drinking and driving and car design. Although these varied functions protect the public health and were often originally developed to improve it, most are managerially and professionally separated from today’s public-health departments. So public-health professionals in the NHS, armed with evidence of the cause of a disease problem, must frequently act as advocates for health across many agencies where they play no formal management part. They must also seek to build alliances and add a health perspective to the policies of other services wherever possible.
Epidemiology is the principal diagnostic method of public health. It is de?ned as the study of the distribution and determinants of health-related states in speci?ed populations, and the application of this study to the control of health problems. Public-health practitioners also draw on many other skills, such as those of statisticians, sociologists, anthropologists, economists and policy analysts in identifying and trying to resolve the health problems of the societies they serve. Treatments proposed are likely to extend well beyond the clinic or hospital and may include recommendations for measures to resolve poverty, improve sanitation or housing, control pollution, change lifestyles such as smoking, improve nutrition, or change health services. At times of acute EPIDEMIC, public-health doctors have considerable legal powers granted to enable them to prevent infection from spreading. At other times their work may be more concerned with monitoring, reporting, planning and managing services, and advocating policy changes to politicians so that health is promoted.
The term ‘the public health’ can relate to the state of health of the population, and be represented by measures such as MORTALITY indices
(e.g. perinatal or infant mortality and standardised mortality rates), life expectancy, or measures of MORBIDITY (illness). These can be compared across areas and even countries. Sometimes people refer to a pubic health-care system; this is a publicly funded service, the primary aim of which is to improve health by the use of population-based measures. They may include or be separate from private health-care services for which individuals pay. The structure of these systems varies from country to country, re?ecting di?erent social composition and political priorities. There are, however, some general elements that can be identi?ed:
Surveillance The collection, collation and analysis of data to provide useful information about the distribution and causes of health and disease and related factors in populations. These activities form the basis of epidemiology, which is the diagnostic backbone of public-health practice.
Intervention The design, advocacy and implementation of policies to improve health. This may be through the provison of PREVENTIVE MEDICINE, environmental measures, in?uencing the behaviour of individuals, or the provision of appropriate services to limit disability and handicap. It will lead to advocacy for health, promoting change in many areas of policy including, for example, taxation and improved housing and employment opportunities.
Evaluation Assessment of the ?rst two steps to assess their impact in terms of e?ectiveness, e?ciency, acceptability, accessibility, value for money or other indicators of quality. This enables the programme to be reviewed and changed as necessary.
The practice of public health The situation in the United Kingdom will be described as, even though systems vary, it will give a general impression of the type of work covered. HISTORY Initially, public-health practice related to food, the urban environment and the control of infectious diseases. Early examples include rules in the Bible about avoiding certain foods. These were probably based on practical experience, had gradually been adopted as sensible behaviour, become part of culture and ?nally been incorporated into religious laws. Other examples are the regulations about quarantine for PLAGUE and LEPROSY in the Middle Ages, vaccination against SMALLPOX introduced by William Jenner, and Lind’s use of citrus fruits to prevent SCURVY at sea in the 18th century.
It was during the 19th century, in response to the health problems arising from the rapid growth of urban life, that the foundations of a public-health system were created. The ‘sanitary’ concept was fundamental to these developments. This suggested that overcrowding in insanitary conditions was the cause of most disease epidemics and that improved sanitation measures such as sewerage and clean water supplies would prevent them. Action to introduce such measures were often initiated only after epidemics spread out of the slums and into wealthier and more powerful families. Other problems such as the stench of the River Thames outside the Houses of Parliament also led to a demand for e?ective sanitary control measures. Successive public-health laws were passed by Parliament, initially about sanitation and housing, and then, as scienti?c knowledge grew, about bacterial infections.
In the middle of the 19th century the ?rst medical o?cers of health were appointed with responsibility to report regularly and advise local government about the measures needed to control disease and improve health. Their scope and responsibility widened as society changed and took on a wider welfare role. After more than a century they changed as part of the reforms of the NHS and local government in the 1960s and became more narrowly focused within the health-care system and its management. Increased recognition of the multifactorial causes, costs and limitations of treatment of conditions such as cancer and heart disease, and the emergence of new problems such as AIDS/HIV and BOVINE SPONGIFORM ENCEPHALOPATHY (BSE) have again showed the importance of prevention and a broader approach to health. With it has come recognition that, while disease may be the justi?cation for action, a narrow diseasetreatment-based approach is not always the most e?ective or economic solution. The role of the director of public health (the successor to the medical o?cer of health) is again being expanded, and in 1997 – for the ?rst time in the UK – a government Minister for Public Health was appointed. This reffects not only a greater priority for public health, but also a concern that the health effects of policy should be considered across all parts of government.
(See also ENVIRONMENT AND HEALTH.)... public health
Monoclonal antibodies are produced in a laboratory by stimulating the growth of a large number of antibody-producing cells that are genetically identical. In effect, this process enables antibodies to be tailor-made so that they will react with a particular antigen.
Monoclonal antibodies are used in the study of human cells, hormones, microorganisms, and in the development of vaccines. They are also being used in the diagnosis and treatment of some forms of cancer.... antibody, monoclonal
In the United Kingdom, the 1993 Education Act refers to ‘learning diffculties’: generalised (severe or moderate), or speci?c (e.g. DYSLEXIA, dyspraxia [or APRAXIA], language disorder). The 1991 Social Security (Disability Living Allowance) Regulations use the term ‘severely mentally impaired’ if a person suffers from a state of arrested development or incomplete physical development of the brain which results in severe impairment of intelligence and social functioning. This is distinct from the consequences of DEMENTIA. Though ‘mental handicap’ is widely used, ‘learning disability’ is preferred by the Department of Health.
There is a distinction between impairment (a biological de?cit), disability (the functional consequence) and handicap (the social consequence).
People with profound learning disability are usually unable to communicate adequately and may be seriously movement-impaired. They are totally dependent on others for care and mobility. Those with moderate disability may achieve basic functional literacy (recognition of name, common signs) and numeracy (some understanding of money) but most have a life-long dependency for aspects of self-care (some fastenings for clothes, preparation of meals, menstrual hygiene, shaving) and need supervision for outdoor mobility.
Children with moderate learning disability develop at between half and three-quarters of the normal rate, and reach the standard of an average child of 8–11 years. They become independent for self-care and public transport unless they have associated disabilities. Most are capable of supervised or sheltered employment. Living independently and raising a family may be possible.
Occurrence Profound learning disability affects about 1 in 1,000; severe learning disability 3 in 1,000; and moderate learning disability requiring special service, 1 per cent. With improved health care, survival of people with profound or severe learning disability is increasing.
Causation Many children with profound or severe learning disability have a diagnosable biological brain disorder. Forty per cent have a chromosome disorder – see CHROMOSOMES (three quarters of whom have DOWN’S (DOWN) SYNDROME); a further 15 per cent have other genetic causes, brain malformations or recognisable syndromes. About 10 per cent suffered brain damage during pregnancy (e.g. from CYTOMEGALOVIRUS (CMV) infection) or from lack of oxygen during labour or delivery. A similar proportion suffer postnatal brain damage from head injury – accidental or otherwise – near-miss cot death or drowning, cardiac arrest, brain infection (ENCEPHALITIS or MENINGITIS), or in association with severe seizure disorders.
Explanations for moderate learning disability include Fragile X or other chromosome abnormalities in a tenth, neuro?bromatosis (see VON RECKLINGHAUSEN’S DISEASE), fetal alcohol syndrome and other causes of intra-uterine growth retardation. Genetic counselling should be considered for children with learning disability. Prenatal diagnosis is sometimes possible. In many children, especially those with mild or moderate disability, no known cause may be found.
Medical complications EPILEPSY affects 1 in 20 with moderate, 1 in 3 with severe and 2 in 3 with profound learning disability, although only 1 in 50 with Down’s syndrome is affected. One in 5 with severe or profound learning disability has CEREBRAL PALSY.
Psychological and psychiatric needs Over half of those with profound or severe – and many with moderate – learning disability show psychiatric or behavioural problems, especially in early years or adolescence. Symptoms may be atypical and hard to assess. Psychiatric disorders include autistic behaviour (see AUTISM) and SCHIZOPHRENIA. Emotional problems include anxiety, dependence and depression. Behavioural problems include tantrums, hyperactivity, self-injury, passivity, masturbation in public, and resistance to being shaved or helped with menstrual hygiene. There is greater vulnerability to abuse with its behavioural consequences.
Respite and care needs Respite care is arranged with link families for children or sta?ed family homes for adults where possible. Responsibility for care lies with social services departments which can advise also about bene?ts.
Education Special educational needs should be met in the least restrictive environment available to allow access to the national curriculum with appropriate modi?cation and support. For older children with learning disability, and for young children with severe or profound learning disability, this may be in a special day or boarding school. Other children can be provided for in mainstream schools with extra classroom support. The 1993 Education Act lays down stages of assessment and support up to a written statement of special educational needs with annual reviews.
Pupils with learning disability are entitled to remain at school until the age of 19, and most with severe or profound learning disability do so. Usually those with moderate learning disability move to further education after the age of 16.
Advice is available from the Mental Health Foundation, the British Institute of Learning Disabilities, MENCAP (Royal Society for Mentally Handicapped Children and Adults), and ENABLE (Scottish Society for the Mentally Handicapped).... learning disability
Aortography is used if surgery is needed to treat an aneurysm (ballooning of the aorta).... aortography
Arterioles branch to form capillaries.
They have muscular walls, and their nerve supply enables them to be narrowed or widened to meet the blood-flow needs of tissues they supply.... arteriole
Only a small minority of those exposed to M. leprae develop the disease. The incubation period is 3–5 years or longer. The major clinical manifestations involve skin and nerves: the former range from depigmented, often anaesthetic areas, to massive nodules; nerve involvement ranges from localised nerve swelling(s) to extensive areas of anaesthesia. Advanced nerve destruction gives rise to severe deformities: foot-drop, wrist-drop, claw-foot, extensive ulceration of the extremities with loss of ?ngers and toes, and bone changes. Eye involvement can produce blindness. Laryngeal lesions produce hoarseness and more serious sequelae. The diagnosis is essentially a clinical one; however, skin-smears, histological features and the lepromin skin-test help to con?rm the diagnosis and enable the form of disease to be graded.
Although the World Health Organisation had originally hoped to eliminate leprosy worldwide by 2000, that has proved an unrealistic target. The reason is an absence of basic information. Doctors are unable to diagnose the disorder before a patient starts to show symptoms; meanwhile he or she may have already passed on the infection. Doctors do not know exactly how transmission occurs or how it infects humans – nor do they know at what point a carrier of the bacterium may infect others. The incidence of new infections is still more than 650,000 cases a year or about 4.5 cases per 10,000 people in those countries worst affected by the disease.
Treatment Introduction of the sulphone compound, dapsone, revolutionised management of the disease. More recently, rifampicin and clofazimine have been added as ?rst-line drugs for treatment. Second-line drugs include minocycline, o?oxacin and clarithromycin; a number of regimens incorporating several of these compounds (multi-drug regimens – introduced in 1982) are now widely used. A three-drug regime is recommended for multi-bacillary leprosy and a two-drug one for parcibacillary leprosy. Dapsone resistance is a major problem worldwide, but occurs less commonly when multi-drug regimens are used. Older compounds – ethionamide and prothionamide
– are no longer used because they are severely toxic to the liver. Corticosteroids are sometimes required in patients with ‘reversal reaction’. Supportive therapy includes physiotherapy; both plastic and orthopaedic surgery may be necessary in advanced stages of the disease. Improvement in socio-economic conditions, and widespread use of BCG vaccination are of value as preventive strategies. Early diagnosis and prompt institution of chemotherapy should prevent long-term complications.... leprosy
It is a classical example of an autoimmune disease (see AUTOIMMUNITY). The body develops ANTIBODIES which interfere with the working of the nerve endings in muscle that are acted on by ACETYLCHOLINE. It is acetylcholine that transmits the nerve impulses to muscles: if this transmission cannot be e?ected, as in myasthenia gravis, then the muscles are unable to contract. Not only the voluntary muscles, but those connected with the acts of swallowing, breathing, and the like, become progressively weaker. Rest and avoidance of undue exertion are necessary, and regular doses of neostigmine bromide, or pyridostigmine, at intervals enable the muscles to be used and in some cases have a curative e?ect. These drugs act by inhibiting the action of cholinesterase – an ENZYME produced in the body which destroys any excess of acetylcholine. In this way they increase the amount of available acetylcholine which compensates for the deleterious e?ect of antibodies on the nerve endings.
The THYMUS GLAND plays the major part in the cause of myasthenia gravis, possibly by being the source of the original acetylcholine receptors to which the antibodies are being formed. Thymectomy (removal of the thymus) is often used in the management of patients with myasthenia gravis. The incidence of remission following thymectomy increases with the number of years after the operation. Complete remission or substantial improvement can be expected in 80 per cent of patients.
The other important aspect in the management of patients with myasthenia gravis is IMMUNOSUPPRESSION. Drugs are now available that suppress antibody production and so reduce the concentration of antibodies to the acetylcholine receptor. The problem is that they not only suppress abnormal antibody production, but also suppress normal antibody production. The main groups of immunosuppressive drugs used in myasthenia gravis are the CORTICOSTEROIDS and AZATHIOPRINE. Improvement following steroids may take several weeks and an initial deterioration is often found during the ?rst week or ten days of treatment. Azathioprine is also e?ective in producing clinical improvement and reducing the antibodies to acetylcholine receptors. These effects occur more slowly than with steroids, and the mean time for an azathioprine remission is nine months.
The Myasthenia Gravis Association, which provides advice and help to sufferers, was created and is supported by myasthenics, their families and friends.... myasthenia gravis
In medicine, the term usually refers to copies of cells, genes, or organisms.
Clones of cells are all descended from one original cell.
In many types of cancer, cells are thought to be derived from one abnormal cell.
Clones of genes are duplicates of a single gene.
In research, several copies of a gene can be made to enable the gene to be studied in detail.
Clones of organisms are produced by removing the nuclei from cells of a donor individual and transplanting them into the egg cells of another individual.
When the eggs mature into living plants or animals, they are all identical to the donor.... clone
During a bite by the female mosquito, one or more sporozoites – a stage in the life-cycle of the parasite – are injected into the human circulation; these are taken up by the hepatocytes (liver cells). Following division, merozoites (minute particles resulting from the division) are liberated into the bloodstream where they invade red blood cells. These in turn divide, releasing further merozoites. As merozoites are periodically liberated into the bloodstream, they cause the characteristic fevers, rigors, etc.
Malaria occurs in many tropical and subtropical countries; P. falciparum is, however, con?ned very largely to Africa, Asia and South America. Malaria is present in increasingly large areas; in addition, the parasites are developing resistance to various preventative and treatment drugs. The disease constitutes a signi?cant problem for travellers, who must obtain sound advice on chemoprophylaxis before embarking on tropical trips – especially to a rural area where intense transmission can occur. Transmission has also been recorded at airports, and following blood transfusion.
The World Health Organisation (WHO) has listed malaria as one of Europe’s top ten infectious diseases. In 1992, 20,000 cases were reported: this had risen to more than 200,000 by the late 1990s. The resurgence of malaria has been worldwide, in part the result of the development of resistant strains of the disease, and in part because many countries have failed (or been unable) to implement environmental measures to eliminate mosquitoes. Nearly 40 years ago the WHO forecast that by 1980 only four million people would be affected worldwide; now, at the beginning of the 21st century, around 500 million people a year are contracting malaria with about 3,000 people a day dying from the infection – as many as 70 per cent of them children under the age of ?ve, according to WHO ?gures. The apparently steady advance of global warming means that countries with temperate climates may well warm up su?ciently to enable malaria to become established as an ENDEMIC disease. In any case, the great increase in international air travel has exposed many more people to the risk of malaria, and infected individuals may not exhibit symptoms until they are back home. Doctors seeing a recent traveller with unexplained pyrexia and illness should consider the possibility of malarial infection.
Diagnosis is by demonstration of trophozoites – a stage in the parasite’s life-cycle that takes place in red blood cells – in thick/thin blood-?lms of peripheral blood. Serological tests are of value in deciding whether an individual has had a past infection, but are of no value in acute disease.
P. vivax and P. ovale infections cause less severe disease than P. falciparum (see below), although overall there are many clinical similarities; acute complications are unusual, but chronic ANAEMIA is often present. Primaquine is necessary to eliminate the exoerythrocytic cycle in the hepatocyte (liver cell).
P. falciparum Complications of P. falciparum infection include cerebral involvement (see BRAIN – Cerebrum), due to adhesion of immature trophozoites on to the cerebral vascular endothelium; these lead to a high death rate when inadequately treated. Renal involvement (frequently resulting from HAEMOGLOBINURIA), PULMONARY OEDEMA, HYPOTENSION, HYPOGLYCAEMIA, and complications in pregnancy are also important. In complicated disease, HAEMODIALYSIS and exchange TRANSFUSION have been used. No adequate controlled trial using the latter regimen has been carried out, however, and possible bene?ts must be weighed against numerous potential side-effects – for instance, the introduction of a wide range of infections, overload of the circulatory system with infused ?uids, and other complications.
P. malariae usually produces a chronic infection, and chronic renal disease (nephrotic syndrome) is an occasional sequel, especially in tropical Africa.
Gross SPLENOMEGALY (hyper-reactive malarious splenomegaly, or tropical splenomegaly syndrome) can complicate all four human Plasmodium spp. infections. The syndrome responds to long-term malarial chemoprophylaxis. BURKITT’S LYMPHOMA is found in geographical areas where malaria infection is endemic; the EPSTEIN BARR VIRUS is aetiologically involved.
Prophylaxis Malaria specialists in the United Kingdom have produced guidance for residents travelling to endemic areas for short stays. Drug choice takes account of:
risk of exposure to malaria;
extent of drug resistance;
e?cacy of recommended drugs and their side-effects;
criteria relevant to the individual (e.g. age, pregnancy, kidney or liver impairment). Personal protection against being bitten by
mosquitoes is essential. Permethrinimpregnated nets are an e?ective barrier, while skin barrier protection and vaporised insecticides are helpful. Lotions, sprays or roll-on applicators all containing diethyltoluamide (DEET) are safe and work when put on the skin. Their e?ect, however, lasts only for a few hours. Long sleeves and trousers should be worn after dark.
Drug prophylaxis should be started at least a week before travelling into countries where malaria is endemic (two or three weeks in the case of me?oquine). Drug treatment should be continued for at least four weeks after leaving endemic areas. Even if all recommended antimalarial programmes are followed, it is possible that malaria may occur any time up to three months afterwards. Medical advice should be sought if any illness develops. Chloroquine can be used as a prophylactic drug where the risk of resistant falciparum malaria is low; otherwise, me?oquine or proguanil hydrochloride should be used. Travellers to malaria-infested areas should seek expert advice on appropriate prophylactic treatment well before departing.
Treatment Various chemoprophylactic regimes are widely used. Those commmonly prescribed include: chloroquine + paludrine, me?oquine, and Maloprim (trimethoprim + dapsone); Fansidar (trimethoprim + sulphamethoxazole) has been shown to have signi?cant side-effects, especially when used in conjunction with chloroquine, and is now rarely used. No chemotherapeutic regimen is totally e?ective, so other preventive measures are again being used. These include people avoiding mosquito bites, covering exposed areas of the body between dusk and dawn, and using mosquito repellents.
Chemotherapy was for many years dominated by the synthetic agent chloroquine. However, with the widespread emergence of chloroquine-resistance, quinine is again being widely used. It is given intravenously in severe infections; the oral route is used subsequently and in minor cases. Other agents currently in use include me?oquine, halofantrine, doxycycline, and the artemesinin alkaloids (‘qinghaosu’).
Researchers are working on vaccines against malaria.... malaria
Among the smallest and simplest microorganisms are the viruses. First described as ?lterable agents, and ranging in size from 20–30 nm to 300 nm, they may be directly visualised only by electron microscopy. They consist of a core of deoxyribonucleic or ribonucleic acid (DNA or RNA) within a protective protein coat, or capsid, whose subunits confer a geometric symmetry. Thus viruses are usually cubical (icosahedral) or helical; the larger viruses (pox-, herpes-, myxo-viruses) may also have an outer envelope. Their minimal structure dictates that viruses are all obligate parasites, relying on living cells to provide essential components for their replication. Apart from animal and plant cells, viruses may infect and replicate in bacteria (bacteriophages) or fungi (mycophages), which are damaged in the process.
Bacteria are larger (0·01–5,000 µm) and more complex. They have a subcellular organisation which generally includes DNA and RNA, a cell membrane, organelles such as ribosomes, and a complex and chemically variable cell envelope – but, unlike EUKARYOTES, no nucleus. Rickettsiae, chlamydia, and mycoplasmas, once thought of as viruses because of their small size and absence of a cell wall (mycoplasma) or major wall component (chlamydia), are now acknowledged as bacteria; rickettsiae and chlamydia are intracellular parasites of medical importance. Bacteria may also possess additional surface structures, such as capsules and organs of locomotion (?agella) and attachment (?mbriae and stalks). Individual bacterial cells may be spheres (cocci); straight (bacilli), curved (vibrio), or ?exuous (spirilla) rods; or oval cells (coccobacilli). On examination by light microscopy, bacteria may be visible in characteristic con?gurations (as pairs of cocci [diplococci], or chains [streptococci], or clusters); actinomycete bacteria grow as ?laments with externally produced spores. Bacteria grow essentially by increasing in cell size and dividing by ?ssion, a process which in ideal laboratory conditions some bacteria may achieve about once every 20 minutes. Under natural conditions, growth is usually much slower.
Eukaryotic micro-organisms comprise fungi, algae, and protozoa. These organisms are larger, and they have in common a well-developed internal compartmentation into subcellular organelles; they also have a nucleus. Algae additionally have chloroplasts, which contain photosynthetic pigments; fungi lack chloroplasts; and protozoa lack both a cell wall and chloroplasts but may have a contractile vacuole to regulate water uptake and, in some, structures for capturing and ingesting food. Fungi grow either as discrete cells (yeasts), multiplying by budding, ?ssion, or conjugation, or as thin ?laments (hyphae) which bear spores, although some may show both morphological forms during their life-cycle. Algae and protozoa generally grow as individual cells or colonies of individuals and multiply by ?ssion.
Micro-organisms of medical importance include representatives of the ?ve major microbial groups that obtain their essential nutrients at the expense of their hosts. Many bacteria and most fungi, however, are saprophytes (see SAPROPHYTE), being major contributors to the natural cycling of carbon in the environment and to biodeterioration; others are of ecological and economic importance because of the diseases they cause in agricultural or horticultural crops or because of their bene?cial relationships with higher organisms. Additionally, they may be of industrial or biotechnological importance. Fungal diseases of humans tend to be most important in tropical environments and in immuno-compromised subjects.
Pathogenic (that is, disease-causing) microorganisms have special characteristics, or virulence factors, that enable them to colonise their hosts and overcome or evade physical, biochemical, and immunological host defences. For example, the presence of capsules, as in the bacteria that cause anthrax (Bacillus anthracis), one form of pneumonia (Streptococcus pneumoniae), scarlet fever (S. pyogenes), bacterial meningitis (Neisseria meningitidis, Haemophilus in?uenzae) is directly related to the ability to cause disease because of their antiphagocytic properties. Fimbriae are related to virulence, enabling tissue attachment – for example, in gonorrhoea (N. gonorrhoeae) and cholera (Vibrio cholerae). Many bacteria excrete extracellular virulence factors; these include enzymes and other agents that impair the host’s physiological and immunological functions. Some bacteria produce powerful toxins (excreted exotoxins or endogenous endotoxins), which may cause local tissue destruction and allow colonisation by the pathogen or whose speci?c action may explain the disease mechanism. In Staphylococcus aureus, exfoliative toxin produces the staphylococcal scalded-skin syndrome, TSS toxin-1 toxic-shock syndrome, and enterotoxin food poisoning. The pertussis exotoxin of Bordetella pertussis, the cause of whooping cough, blocks immunological defences and mediates attachment to tracheal cells, and the exotoxin produced by Corynebacterium diphtheriae causes local damage resulting in a pronounced exudate in the trachea.
Viruses cause disease by cellular destruction arising from their intracellular parasitic existence. Attachment to particular cells is often mediated by speci?c viral surface proteins; mechanisms for evading immunological defences include latency, change in viral antigenic structure, or incapacitation of the immune system – for example, destruction of CD 4 lymphocytes by the human immunode?ciency virus.... microbiology
structure in the body to be inspected directly. The endoscope is inserted through a natural body opening, such as the mouth or vagina, or into a small incision. The operator can inspect and photograph the organ and carry out a biopsy. Many operations can be performed by passing surgical instruments down an endoscope. (See also minimally invasive surgery.)... endoscopy
links to community pharmacies and social services.
access to NHS Direct information via the Internet and information points in public sites.
publication of a guide on health care for dispatch to callers.... nhs direct
The cause of the pulsation lies in the fact that, at each heartbeat, 80–90 millilitres of blood are driven into the AORTA, and a ?uid wave, distending the vessels as it passes, is transmitted along the ARTERIES all over the body. This pulsation falls away as the arteries grow smaller, and is ?nally lost in the minute capillaries, where a steady pressure is maintained. For this reason, the blood in the veins ?ows steadily on without any pulsation. Immediately after the wave has passed, the artery, by virtue of its great elasticity, regains its former size. The nature of this wave helps the doctor to assess the state of the artery and the action of the heart.
The pulse rate is usually about 70 per minute, but it may vary in health from 50 to 100, and is quicker in childhood and slower in old age than in middle life; it is low (at rest) in physically ?t athletes or other sports people. Fever causes the rate to rise, sometimes to 120 beats a minute or more.
In childhood and youth the vessel wall is so thin that, when su?cient pressure is made to expel the blood from it, the artery can no longer be felt. In old age, however, and in some degenerative diseases, the vessel wall becomes so thick that it may be felt like a piece of whipcord rolling beneath the ?nger.
Di?erent types of heart disease have special features of the pulse associated with them. In atrial FIBRILLATION the great character is irregularity. In patients with an incompetent AORTIC VALVE the pulse is characterised by a sharp rise and sudden collapse. (See HEART, DISEASES OF.)
An instrument known as the SPHYGMOGRAPH registers the arterial waves and a polygraph (an instrument that obtains simultaneous tracings from several di?erent sources such as radial and jugular pulse, apex beat of the heart and ELECTROCARDIOGRAM (ECG)) enables tracings to be taken from the pulse at the wrist and from the veins in the neck and simultaneous events in the two compared.
The pressure of the blood in various arteries is estimated by a SPHYGMOMANOMETER. (See BLOOD PRESSURE.)... pulse
In Britain, for instance, preventive medicine is usually taken to encompass a range of activities whose purpose is:
to reduce the chance of a person contracting a disease or becoming disabled.
to identify either an increased susceptibility to develop a disease, or an early manifestation of a disease at a stage which will still allow treatment to be e?ective. The American College of Preventive Medi
cine (1983) de?ned it as ‘a specialised ?eld of medical practice composed of distinct disciplines which utilise skills focusing on the health of de?ned populations in order to promote and maintain health and well-being and to prevent disease, disability and premature death’.
However de?ned, the spectrum of activities encompassed by preventive medicine is wide and includes actions, such as counselling about lifestyle, where there may not be a clear cut-o? between a preventive and a curative act. For example, advice about smoking and exercise to a recent victim of a myocardial infarction (see under HEART, DISEASES OF) is both essential to treatment and preventive against a future attack. Action aimed at a whole population – such as the addition of ?uoride to drinking-water to protect against dental caries (see under TEETH, DISORDERS OF) – is part of a population-based public-health strategy but would also be widely regarded as preventive medicine.
A common and widely accepted classi?cation of preventive medicine is as follows:
Primary prevention which aims at the complete avoidance of a disease (for example, by immunising a child against an infectious disease – see IMMUNISATION).
Secondary prevention which aims at detecting and curing a disease at an early stage before it has caused any symptoms. This requires ‘screening’ procedures to detect either the early pre-symptomatic condition, or a risk factor which may lead to it. (An example of the former is cervical cytology, where a sample of cells is scraped from the cervix of the UTERUS and examined microscopically for abnormality.
An example of the latter is CHOLESTEROL measurement as part of assessing an individual’s risk of developing ischaemic heart disease (see under HEART, DISEASES OF). If it is signi?cantly raised, dietary or drug treatment can be advised.)
Tertiary prevention aims at minimising the consequences for a patient who already has the disease (e.g. advising people to take more exercise and stop smoking after a heart attack).
Many prefer to limit the term ‘preventive medicine’ to primary and secondary prevention, emphasising the focus on risk-reducing interventions targeted at ‘well’ individuals. Others prefer the wider emphasis because of the importance of a preventive approach in reducing further disability by recognising and treating symptoms early. This can be particularly important in older people, where, for example, vigorous treatment of an orthopaedic problem can enable the patient to maintain physical mobility with all the bene?ts to health that brings. Whether primary, secondary or tertiary prevention, some form of screening question or test is normally necessary to identify a problem.
The range and extent of opportunities for prevention are expanding as research identi?es the causes of diseases and more e?ective treatment becomes feasible. Inevitably there is economic and political debate about the cost-e?ectiveness of prevention versus cure, as well as about the ETHICS. The situation varies in relation to the natural history of the speci?c disease. Some conditions can easily be prevented but once contracted cannot be cured
(e.g. RABIES); others are easily cured but are not yet preventable.
Screening Screening involves carrying out tests either to identify a treatable disease at a very early stage, before it has caused symptoms or damage; or to identify a risk factor which can lead to a disease. The tests might be by simple questioning (e.g. ‘Do you smoke cigarettes?’ – this predicts a considerable increase in the risk of chronic bronchitis, heart disease, bronchial cancer and many other diseases, and enables targeted advice and help to stop smoking to be given). Other screening tests involve carrying out complex special investigations such as blood tests or the microscopic investigations of cells – for example, for precancerous changes.
Many conditions can be identi?ed at an early stage before they cause symptoms or signs of disease and in time for e?ective treatment to be carried out. Inevitably, some of the screening tests proposed can be expensive (particularly if used in large populations), painful or inaccurate and may not improve the results of treatment. Screening can also provoke considerable anxiety in those waiting for tests or results. Therefore, over the years considerable research has been carried out into the appropriateness and ethics of screening, and the World Health Organisation in 1968 identi?ed a set of rules for evaluating screening tests:
The condition sought should be an important health problem, for which there should be an accepted treatment for patients with recognised disease.
Facilities for diagnosis and treatment should be available if a case is found.
The screening test or examination must be suitable and valid. A false positive test will cause massive anxiety and also considerable expense in proving that there is no disease. Similarly, false negatives can lead people to be reassured and to ignore serious symptoms until too late. If large numbers of positive tests or false positives occur during a screening programme, health services can be swamped.
The test, and any treatment as a possible result, should be acceptable. For example, there is little point in screening for a fetal abnormality which, if found, would lead to a recommendation for termination if the mother will refuse it on religious or moral grounds.
Screening tests also need to be considered from an economic perspective and the cost of case-?nding (including diagnosis and treatment of patients diagnosed) balanced in relation to possible expenditure on medical care as a whole.
Finally the programme should re?ect the natural history of the disease, and case-?nding should normally be a continuing process and not a ‘once for all’ project. If these rules are followed, considerable
bene?ts can result from well-planned and well-managed screening programmes, and they form an important part of any health-care system. The extent to which manipulation of genetic material will be added to more traditional approaches such as counselling, immunisation and drug treatment cannot yet be predicted but, as time goes by, it is often likely to be ethical and social controls which limit developments rather than technical and scienti?c limits.... preventive medicine
Development of such mechanical and biomechanical devices points the way to a much wider use of e?ective prostheses, enabling people who would previously have died or been severely handicapped to lead normal or near normal lives. The technical hazards that have already been overcome provide a sound foundation for future successes. Progress so far in producing prostheses should also ensure that organ replacement is free from the serious ethical problems that surround the use of genetic manipulation to cure or prevent serious diseases (see ETHICS).
Limbs These are best made to meet the individual’s requirements but can be obtained ‘o? the shelf’. Arti?cial joints normally comprise complex mechanisms to stimulate ?exion and rotation movements. Leg prostheses are generally more useful than those for arms, because leg movements are easier to duplicate than those of the arm. Modern electronic circuitry that enables nerve impulses to be picked up and converted into appropriate movements is greatly improving the e?ectiveness of limb prostheses.
Eyes Arti?cial eyes are worn both for appearance and for psychological reasons. They are made of glass or plastic, and are thin shells of a boat-shape, representing the front half of the eye which has been removed. The stump which is left has still the eye-muscles in it, and so the arti?cial eye still has the power of moving with the other. A glass eye has to be replaced by a new one every year. Plastic eyes have the advantage of being more comfortable to wear, being more durable, and being unbreakable. Research is taking place aimed at creating a silicon chip that stimulates the visual cortex and thus helps to restore sight to the blind.
Dental prostheses is any arti?cial replacement of a tooth. There are three main types: a crown, a bridge and a denture. A crown is the replacement of the part of a tooth which sticks through the gum. It is ?xed to the remaining part of the tooth and may be made of metal, porcelain, plastic or a combination of these. A bridge is the replacement of two or three missing teeth and is usually ?xed in place. The replacement teeth are held in position by being joined to one or more crowns on the adjacent teeth. A denture is a removable prosthesis used to replace some or all the teeth. The teeth are made of plastic or porcelain and the base may be of plastic or metal. Removable teeth may be held more ?rmly by means of implants.
Heart The surgical replacement of stenosed or malfunctioning heart-valves with metal or plastic, human or pig valves has been routinely carried out for many years. So too has been the insertion into patients with abnormal heart rhythms of battery-driven arti?cial pacemakers (see CARDIAC PACEMAKER) to restore normal function. The replacement of a faulty heart with an arti?cial one is altogether more challenging. The ?rst working attempt to create an arti?cial heart took place in the early 1980s. Called the Jarvik-7, it had serious drawbacks: patients had to be permanently connected to apparatus the size of an anaesthetic trolley; and it caused deaths from infection and clotting of the blood. As a result, arti?cial hearts have been used primarily as bridging devices to keep patients alive until a suitable donor heart for transplantation can be found. Recent work in North America, however, is developing arti?cial hearts made of titanium and dacron. One type is planted into the chest cavity next to the patient’s own heart to assist it in its vital function of pumping blood around the body. Another replaces the heart completely. Eventually, it is probable that arti?cial hearts will replace heart transplants as the treatment of choice in patients with serious heart disorders.
Liver Arti?cial livers work in a similar way to kidney dialysis machines (see DIALYSIS). Blood is removed from the body and passed through a machine where it is cleaned and treated and then returned to the patient. The core of the device comprises several thousand ?exible membrane tubules on which live liver cells (from pigs or people) have been cultured. There is an exchange of biological molecules and water with the ‘circulating’ blood, and the membrane also screens the ‘foreign’ cells from the patient’s immune system, thus preventing any antagonistic immune reaction in the recipient.
Nose The making of a new nose is the oldest known operation in plastic surgery, Hindu records of such operations dating back to 1,000 BC. Loss of a nose may be due to eroding disease, war wounds, gun-shot wounds or dog bites. In essence the operation is the same as that practised a thousand years before Christ: namely the use of a skin graft, brought down from the forehead. Alternative sources of the skin graft today are skin from the arm, chest or abdomen. As a means of support, the new nose is built round a graft of bone or of cartilage from the ear.... prosthesis
Each ear has 3 distinct regions: the outer, middle, and inner ear. Sound waves are channelled through the ear canal to the middle ear, from where a complex system of membranes and tiny bones conveys the vibrations to the inner ear. The vibrations are converted into nerve impulses in the cochlea. These impulses travel along the auditory nerve to the medulla of the brain. From there, they pass via the thalamus to the superior temporal gyrus, part of the cerebral cortex involved in perceiving sound. (See also deafness.)... hearing
The scheme is aimed at reducing the risks of infections, such as HIV and hepatitis, transmitted by the sharing of contaminated needles.... needle exchange
The person lies in a way that allows the secretions to drain by gravity into the trachea, from where they are coughed up.
Tapping the person’s chest with cupped hands can help to loosen sticky secretions.... postural drainage
Radiological methods provide images of the body in a noninvasive way so that exploratory surgery is not needed.
The techniques also enable instruments (such as needles and catheters) to be accurately guided into different parts of the body for diagnosis and treatment.
This is called interventional radiology.... radiology
– an early graded return to activity gives the best long-term results, but doing too much too soon runs the risk of exacerbating the original injury.
Chronic (overuse) injuries affecting the bones (see BONE), tendons (see TENDON) or BURSAE of the JOINTS are common in many sports. Examples include chronic INFLAMMATION of the common extensor tendon where it
attaches to the later EPICONDYLE of the humerus – common in throwers and racquet sportspeople – and stress fractures of the TIBIA or METATARSAL BONES of the foot in runners. After an initial period of rest, management often involves coaching that enables the athlete to perform the repetitive movement in a less injury-susceptible manner.
Exercise physiology is the science of measuring athletic performance and physical ?tness for exercise. This knowledge is applied to devising and supervising training regimens based on scienti?c principles. Physical ?tness depends upon the rate at which the body can deliver oxygen to the muscles, known as the VO2max, which is technically di?cult to measure. The PULSE rate during and after a bout of exercise serves as a good proxy of this measurement.
Regulation of sport Sports medicine’s role is to minimise hazards for participants by, for example, framing rule-changes which forbid collapsing the scrum, which has reduced the risk of neck injury in rugby; and in the detection of the use of drugs taken to enhance athletic performance. Such attempts to gain an edge in competition undermine the sporting ideal and are banned by leading sports regulatory bodies. The Olympic Movement Anti-Doping Code lists prohibited substances and methods that could be used to enhance performance. These include some prohibited in certain circumstances as well as those completely banned. The latter include:
stimulants such as AMPHETAMINES, bromantan, ca?eine, carphedon, COCAINE, EPHEDRINE and certain beta-2 agonists.
NARCOTICS such as DIAMORPHINE (heroin), MORPHINE, METHADONE HYDROCHLORIDE and PETHIDINE HYDROCHLORIDE.
ANABOLIC STEROIDS such as methandione, NANDROLONE, stanazol, TESTOSTERONE, clenbuterol, androstenedone and certain beta-2 agonists.
peptide HORMONES, mimetics and analogues such as GROWTH HORMONE, CORTICOTROPHIN, CHORIONIC GONADOTROPHIC HORMONE, pituitary and synthetic GONADOTROPHINS, ERYTHROPOIETIN and INSULIN. (The list produced above is not comprehen
sive: full details are available from the governing bodies of relevant sports.) Among banned methods are blood doping (pre-competition administration of an athlete’s own previously provided and stored blood), administration of arti?cial oxygen carriers or plasma expanders. Also forbidden is any pharmacological, chemical or physical manipulation to affect the results of authorised testing.
Drug use can be detected by analysis of the URINE, but testing only at the time of competition is unlikely to detect drug use designed to enhance early-season training; hence random testing of competitive athletes is also used.
The increasing professionalism and competitiveness (among amateurs and juveniles as well as professionals) in sports sometimes results in pressures on participants to get ?t quickly after injury or illness. This can lead to
players returning to their activity before they are properly ?t – sometimes by using physical or pharmaceutical aids. This practice can adversely affect their long-term physical capabilities and perhaps their general health.... sports medicine
Function As well as the stomach’s prime role in physically and physiologically breaking down the food delivered via the oesophagus, it also acts as a storage organ – a function that enables people to eat three or four times a day instead of every 30 minutes or so as their metabolic needs would otherwise demand. Gastric secretion is stimulated by the sight and smell of food and its subsequent arrival in the stomach. The secretions, which contain mucus and hydrochloric acid (the latter produced by parietal cells), sterilise the food; pepsin, a digestive ENZYME in the gastric juices, breaks down the protein in food. The juices also contain intrinsic factor, vital for the absorption of vitamin B12 when the chyle – as the stomach contents are called – reaches the intestine. This chyle is of creamy consistency and is the end product of enzymic action and rhythmic contractions of the stomach’s muscles every 30 seconds or so. Food remains in the stomach for varying lengths of time depending upon its quantity and nature. At regular intervals a bolus of chyle is forced into the duodenum by contractions of the stomach muscles coordinated with relaxation of the pyloric sphincter.... stomach
It takes up to 15 years to train a surgeon from the time at which he or she enters medical school; after graduating as a doctor a surgeon has to pass a comprehensive two-stage examination to become a fellow of one of the ?ve recognised colleges of surgeons in the UK and Ireland.
Surgery is carried out in specially designed operating theatres. Whereas it used to necessitate days and sometimes weeks of inpatient hospital care, many patients are now treated as day patients, often under local anaesthesia, being admitted in the morning and discharged later in the day.
More complex surgery, such as transplantation and neurosurgery, usually necessitates patients being nursed post-operatively in high-dependency units (see INTENSIVE THERAPY UNIT (ITU)) before being transferred to ordinary recovery wards. Successful surgery requires close co-operation between surgeons, physicians and radiologists as well as anaesthetists (see ANAESTHESIA), whose sophisticated techniques enable surgeons to undertake long and complex operations that were unthinkable 30 or more years ago. Surgical treatment of cancers is usually done in collaboration with oncologists. Successful surgery is also dependent on the skills of supporting sta? comprising nurses and operating-theatre technicians and the availability of up-to-date facilities.... surgery
Sperm are produced within the seminiferous tubules of the testes and mature in the epididymis.
Production and development of sperm cells is dependent on testosterone and on gonadotrophin hormones secreted by the pituitary gland.
Sperm production starts at puberty.... sperm
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