A tiny, single-celled living organism.
Most microorganisms are too small to be seen by the naked eye.
Most microorganisms are too small to be seen by the naked eye.
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
(See also contagious; infectious disease.)... communicable disease
Microorganisms are collected from the site of an infection and cultured to produce adequate amounts so that tests to identy them can be performed.
Cells may be cultured to diagnose disorders prenatally and for study of chromosomes (see chromosome analysis).
Some tissues, such as skin, may be cultured to produce larger amounts for grafting.... culture
Common bacteria, such as staphylococci, are the usual cause of abscesses, although fungal infections can cause them, and amoebae are an important cause of liver abscesses (see amoebiasis). Infectious organisms usually reach internal organs via the bloodstream, or they penetrate tissues under the skin through a wound.
An abscess may cause pain, depending on where it occurs. Most larger abscesses cause fever, sweating, and malaise. Those that are close to the skin often cause obvious redness and swelling.
Antibiotics, antifungal drugs, or amoebicides are usually prescribed as appropriate.
Most abscesses also need to be drained (see drain, surgical), and in some cases a tube may be left in place to allow continuous drainage.
Some abscesses burst and drain spontaneously.
Occasionally, an abscess within a vital organ damages enough surrounding tissue to cause permanent loss of normal function, or even death.... abscess
Bacteria and viruses are disease-causing microorganisms.... organism
Aerobic bacteria require oxygen to grow and multiply; in the body, these are most commonly found on the skin or in the respiratory system. Anaerobic bacteria thrive where there is no oxygen, deep within tissue or wounds. They reproduce by simple division, which can take place every 20 minutes. Some bacteria also produce spores that can survive high temperatures, dry conditions, and lack of nourishment; and some produce poisons (either endotoxins or exotoxins) that are harmful to human cells.
The body’s immune system attacks invading bacteria, but in some cases treatment with antibiotic drugs is necessary and will speed recovery. Superficial inflammation and infected wounds may be treated with antiseptics. Immunity to invading bacterial diseases, such as some types of meningitis, can be acquired by active immunization. (See also infectious disease.)... bacteria
Nutritional Profile Energy value (calories per serving): Moderate Protein: High Fat: Moderate Saturated fat: High Cholesterol: Moderate Carbohydrates: None Fiber: None Sodium: Low Major vitamin contribution: B vitamins Major mineral contribution: Iron, phosphorus, zinc
About the Nutrients in This Food Like fish, pork, poultry, milk, and eggs, beef has high-quality proteins, with sufficient amounts of all the essential amino acids. Beef fat is slightly more highly saturated than pork fat, but less saturated than lamb fat. All have about the same amount of cholesterol per serving. Beef is an excellent source of B vitamins, including niacin, vitamin B6, and vitamin B12, which is found only in animal foods. Lean beef pro- vides heme iron, the organic iron that is about five times more useful to the body than nonheme iron, the inorganic form of iron found in plant foods. Beef is also an excellent source of zinc. One four-ounce serving of lean broiled sirloin steak has nine grams fat (3.5 g saturated fat), 101 mg cholesterol, 34 g protein, and 3.81 mg iron (21 percent of the R DA for a woman, 46 percent of the R DA for a man). One four-ounce serving of lean roast beef has 16 g fat (6.6 g saturated fat), 92 mg cholesterol, and 2.96 mg iron (16 percent of the R DA for a woman, 37 percent of the R DA for a man).
The Most Nutritious Way to Serve This Food With a food rich in vitamin C. Ascorbic acid increases the absorption of iron from meat. * These values apply to lean cooked beef.
Diets That May Restrict or Exclude This Food Controlled-fat, low-cholesterol diet Low-protein diet (for some forms of kidney disease)
Buying This Food Look for: Fresh, red beef. The fat should be white, not yellow. Choose lean cuts of beef with as little internal marbling (streaks of fat) as possible. The leanest cuts are flank steak and round steak; rib steaks, brisket, and chuck have the most fat. USDA grading, which is determined by the maturity of the animal and marbling in meat, is also a guide to fat content. U.S. prime has more marbling than U.S. choice, which has more marbling than U.S. good. All are equally nutritious; the difference is how tender they are, which depends on how much fat is present. Choose the cut of meat that is right for your recipe. Generally, the cuts from the cen- ter of the animal’s back—the rib, the T-Bone, the porterhouse steaks—are the most tender. They can be cooked by dry heat—broiling, roasting, pan-frying. Cuts from around the legs, the underbelly, and the neck—the shank, the brisket, the round—contain muscles used for movement. They must be tenderized by stewing or boiling, the long, moist cooking methods that break down the connective tissue that makes meat tough.
Storing This Food Refrigerate raw beef immediately, carefully wrapped to prevent its drippings from contami- nating other foods. Refrigeration prolongs the freshness of beef by slowing the natural multi- plication of bacteria on the meat surface. Unchecked, these bacteria will convert proteins and other substances on the surface of the meat to a slimy film and change meat’s sulfur-contain- ing amino acids methionine and cystine into smelly chemicals called mercaptans. When the mercaptans combine with myoglobin, they produce the greenish pigment that gives spoiled meat its characteristic unpleasant appearance. Fresh ground beef, with many surfaces where bacteria can live, should be used within 24 to 48 hours. Other cuts of beef may stay fresh in the refrigerator for three to five days.
Preparing This Food Trim the beef carefully. By judiciously cutting away all visible fat you can significantly reduce the amount of fat and cholesterol in each serving. When you are done, clean all utensils thoroughly with soap and hot water. Wash your cutting board, wood or plastic, with hot water, soap, and a bleach-and-water solution. For ultimate safety in preventing the transfer of microorganisms from the raw meat to other foods, keep one cutting board exclusively for raw meats, fish, and poultry, and a second one for everything else. Finally, don’t forget to wash your hands.
What Happens When You Cook This Food Cooking changes the appearance and flavor of beef, alters nutritional value, makes it safer, and extends its shelf life. Browning meat after you cook it does not “seal in the juices,” but it does change the fla- vor by caramelizing sugars on the surface. Because beef’s only sugars are the small amounts of glycogen in the muscles, we add sugars in marinades or basting liquids that may also con- tain acids (vinegar, lemon juice, wine) to break down muscle fibers and tenderize the meat. (Browning has one minor nutritional drawback. It breaks amino acids on the surface of the meat into smaller compounds that are no longer useful proteins.) When beef is cooked, it loses water and shrinks. Its pigments, which combine with oxygen, are denatured (broken into fragments) by the heat and turn brown, the natural color of well-done meat. At the same time, the fats in the beef are oxidized. Oxidized fats, whether formed in cooking or when the cooked meat is stored in the refrigerator, give cooked meat a character- istic warmed-over flavor. Cooking and storing meat under a blanket of antioxidants—catsup or a gravy made of tomatoes, peppers, and other vitamin C-rich vegetables—reduces the oxidation of fats and the intensity of warmed-over flavor. Meat reheated in a microwave oven also has less warmed-over flavor. An obvious nutritional benefit of cooking is the fact that heat lowers the fat content of beef by liquif ying the fat so it can run off the meat. One concrete example of how well this works comes from a comparison of the fat content in regular and extra-lean ground beef. According to research at the University of Missouri in 1985, both kinds of beef lose mass when cooked, but the lean beef loses water and the regular beef loses fat and cholesterol. Thus, while regular raw ground beef has about three times as much fat (by weight) as raw ground extra-lean beef, their fat varies by only 5 percent after broiling. To reduce the amount of fat in ground beef, heat the beef in a pan until it browns. Then put the beef in a colander, and pour one cup of warm water over the beef. Repeat with a second cup of warm water to rinse away fat melted by heating the beef. Use the ground beef in sauce and other dishes that do not require it to hold together. Finally, cooking makes beef safer by killing Salmonella and other organisms in the meat. As a result, cooking also serves as a natural preservative. According to the USDA, large pieces of fresh beef can be refrigerated for two or three days, then cooked and held safely for another day or two because the heat of cooking has reduced the number of bacteria on the surface of the meat and temporarily interrupted the natural cycle of deterioration.
How Other Kinds of Processing Affect This Food Aging. Hanging fresh meat exposed to the air, in a refrigerated room, reduces the moisture content and shrinks the meat slightly. As the meat ages enzymes break down muscle pro- teins, “tenderizing” the beef. Canning. Canned beef does not develop a warmed-over flavor because the high tempera- tures in canning food and the long cooking process alter proteins in the meat so that they act as antioxidants. Once the can is open, however, the meat should be protected from oxygen that will change the flavor of the beef. Curing. Salt-curing preserves meat through osmosis, the physical reaction in which liquids flow across a membrane, such as the wall of a cell, from a less dense to a more dense solution. The salt or sugar used in curing dissolves in the liquid on the surface of the meat to make a solution that is more dense than the liquid inside the cells of the meat. Water flows out of the meat and out of the cells of any microorganisms living on the meat, killing the microor- ganisms and protecting the meat from bacterial damage. Salt-cured meat is much higher in sodium than fresh meat. Freezing. When you freeze beef, the water inside its cells freezes into sharp ice crystals that can puncture cell membranes. When the beef thaws, moisture (and some of the B vitamins) will leak out through these torn cell walls. The loss of moisture is irreversible, but some of the vitamins can be saved by using the drippings when the meat is cooked. Freezing may also cause freezer burn—dry spots left when moisture evaporates from the surface of the meat. Waxed freezer paper is designed specifically to hold the moisture in meat; plastic wrap and aluminum foil are less effective. NOTE : Commercially prepared beef, which is frozen very quickly at very low temperatures, is less likely to show changes in texture. Irradiation. Irradiation makes meat safer by exposing it to gamma rays, the kind of high- energy ionizing radiation that kills living cells, including bacteria. Irradiation does not change the way meat looks, feels or tastes, or make the food radioactive, but it does alter the structure of some naturally occurring chemicals in beef, breaking molecules apart to form new com- pounds called radiolytic products (R P). About 90 percent of R Ps are also found in nonirradiated foods. The rest, called unique radiolytic products (UR P), are found only in irradiated foods. There is currently no evidence to suggest that UR Ps are harmful; irradiation is an approved technique in more than 37 countries around the world, including the United States. Smoking. Hanging cured or salted meat over an open fire slowly dries the meat, kills micro- organisms on its surface, and gives the meat a rich, “smoky” flavor that varies with the wood used in the fire. Meats smoked over an open fire are exposed to carcinogenic chemicals in the smoke, including a-benzopyrene. Meats treated with “artificial smoke flavoring” are not, since the flavoring is commercially treated to remove tar and a-benzopyrene.
Medical Uses and/or Benefits Treating and/or preventing iron deficiency. Without meat in the diet, it is virtually impossible for an adult woman to meet her iron requirement without supplements. One cooked 3.5- ounce hamburger provides about 2.9 mg iron, 16 percent of the R DA for an adult woman of childbearing age. Possible anti-diabetes activity. CLA may also prevent type 2 diabetes, also called adult-onset diabetes, a non-insulin-dependent form of the disease. At Purdue University, rats bred to develop diabetes spontaneously between eight and 10 weeks of age stayed healthy when given CLA supplements.
Adverse Effects Associated with This Food Increased risk of heart disease. Like other foods from animals, beef contains cholesterol and saturated fats that increase the amount of cholesterol circulating in your blood, raising your risk of heart disease. To reduce the risk of heart disease, the National Cholesterol Education Project recommends following the Step I and Step II diets. The Step I diet provides no more than 30 percent of total daily calories from fat, no more than 10 percent of total daily calories from saturated fat, and no more than 300 mg of cholesterol per day. It is designed for healthy people whose cholesterol is in the range of 200 –239 mg/dL. The Step II diet provides 25– 35 percent of total calories from fat, less than 7 percent of total calories from saturated fat, up to 10 percent of total calories from polyunsaturated fat, up to 20 percent of total calories from monounsaturated fat, and less than 300 mg cho- lesterol per day. This stricter regimen is designed for people who have one or more of the following conditions: • Existing cardiovascular disease • High levels of low-density lipoproteins (LDLs, or “bad” cholesterol) or low levels of high-density lipoproteins (HDLs, or “good” cholesterol) • Obesity • Type 1 diabetes (insulin-dependent diabetes, or diabetes mellitus) • Metabolic syndrome, a.k.a. insulin resistance syndrome, a cluster of risk fac- tors that includes type 2 diabetes (non-insulin-dependent diabetes) Increased risk of some cancers. According the American Institute for Cancer Research, a diet high in red meat (beef, lamb, pork) increases the risk of developing colorectal cancer by 15 percent for every 1.5 ounces over 18 ounces consumed per week. In 2007, the National Can- cer Institute released data from a survey of 500,000 people, ages 50 to 71, who participated in an eight-year A AR P diet and health study identif ying a higher risk of developing cancer of the esophagus, liver, lung, and pancreas among people eating large amounts of red meats and processed meats. Food-borne illness. Improperly cooked meat contaminated with E. coli O157:H7 has been linked to a number of fatalities in several parts of the United States. In addition, meats con- taminated with other bacteria, viruses, or parasites pose special problems for people with a weakened immune system: the very young, the very old, cancer chemotherapy patients, and people with HIV. Cooking meat to an internal temperature of 140°F should destroy Salmo- nella and Campylobacter jejuni; 165°F, the E. coli organism; and 212°F, Listeria monocytogenes. Antibiotic sensitivity. Cattle in the United States are routinely given antibiotics to protect them from infection. By law, the antibiotic treatment must stop three days to several weeks before the animal is slaughtered. Theoretically, the beef should then be free of antibiotic residues, but some people who are sensitive to penicillin or tetracycline may have an allergic reaction to the meat, although this is rare. Antibiotic-resistant Salmonella and toxoplasmosis. Cattle treated with antibiotics may pro- duce meat contaminated with antibiotic-resistant strains of Salmonella, and all raw beef may harbor ordinary Salmonella as well as T. gondii, the parasite that causes toxoplasmosis. Toxoplasmosis is particularly hazardous for pregnant women. It can be passed on to the fetus and may trigger a series of birth defects including blindness and mental retardation. Both Salmonella and the T. gondii can be eliminated by cooking meat thoroughly and washing all utensils, cutting boards, and counters as well as your hands with hot soapy water before touching any other food. Decline in kidney function. Proteins are nitrogen compounds. When metabolized, they yield ammonia, which is excreted through the kidneys. In laborator y animals, a sustained high-protein diet increases the flow of blood through the kidneys, accelerating the natural age-related decline in kidney function. Some experts suggest that this may also occur in human beings.
Food/Drug Interactions Tetracycline antibiotics (demeclocycline [Declomycin], doxycycline [ Vibtamycin], methacycline [Rondomycin], minocycline [Minocin], oxytetracycline [Terramycin], tetracycline [Achromycin V, Panmycin, Sumycin]). Because meat contains iron, which binds tetracyclines into com- pounds the body cannot absorb, it is best to avoid meat for two hours before and after taking one of these antibiotics. Monoamine oxidase (MAO) inhibitors. Meat “tenderized” with papaya or a papain powder can interact with the class of antidepressant drugs known as monoamine oxidase inhibi- tors. Papain meat tenderizers work by breaking up the long chains of protein molecules. One by-product of this process is tyramine, a substance that constructs blood vessels and raises blood pressure. M AO inhibitors inactivate naturally occurring enzymes in your body that metabolize tyramine. If you eat a food such as papain-tenderized meat, which is high in tyramine, while you are taking a M AO inhibitor, you cannot effectively eliminate the tyramine from your body. The result may be a hypertensive crisis. Theophylline. Charcoal-broiled beef appears to reduce the effectiveness of theophylline because the aromatic chemicals produced by burning fat speed up the metabolism of the- ophylline in the liver.... beef
Scientists have engineered appropriate genes from other organisms into BACTERIA, or sometimes plants, to accelerate this natural evolutionary process. For e?ective ‘digestion of waste’, a micro-organism must quickly and completely digest organic waste without producing unpleasant smells or noxious gases, be non-pathogenic and be able to reproduce in hostile conditions. For example, American researchers have discovered an anaerobic bacterium that neutralises dangerous chlorinated chemical compounds such as trichlorethane, which can pollute soil, into a harmless molecule called ethens. But the bacteria do not thrive in soil. So the dechlorinating genes in this bacterium are transferred to bacteria that are acclimatised to living in toxic areas and can more e?ciently carry out the required detoxi?cation. Other research has been aimed at detoxifying the byproducts of DDT, a troublesome and resistant pollutant. Bioremediation should prove to be an environmentally friendly and cost-e?ective alternative to waste incineration or chemically based processes for washing contaminated soils.... bioremediation
Recently chemotherapy has become increasingly e?ective in the treatment of cancer. Numerous drugs, generally CYTOTOXIC, are available; great care is required in their selection and to minimise side-effects. Certain tumours are highly sensitive to chemotherapy
– especially testicular tumours, LEUKAEMIA, LYMPHOMA and various tumours occurring in childhood (e.g. Wilm’s tumour – see NEPHROBLASTOMA) – and may even be cured.... chemotherapy
Nutritional Profile Energy value (calories per serving): Moderate Protein: High Fat: High Saturated fat: Moderate Cholesterol: High Carbohydrates: Low Fiber: None Sodium: Moderate to high Major vitamin contribution: Vitamin A, riboflavin, vitamin D Major mineral contribution: Iron, calcium
About the Nutrients in This Food An egg is really three separate foods, the whole egg, the white, and the yolk, each with its own distinct nutritional profile. A whole egg is a high-fat, high-cholesterol, high-quality protein food packaged in a high-calcium shell that can be ground and added to any recipe. The proteins in eggs, with sufficient amounts of all the essential amino acids, are 99 percent digestible, the standard by which all other proteins are judged. The egg white is a high-protein, low-fat food with virtually no cholesterol. Its only important vitamin is riboflavin (vitamin B2), a vis- ible vitamin that gives egg white a slightly greenish cast. Raw egg whites contain avidin, an antinutrient that binds biotin a B complex vitamin for- merly known as vitamin H, into an insoluble compound. Cooking the egg inactivates avidin. An egg yolk is a high-fat, high-cholesterol, high-protein food, a good source of vitamin A derived from carotenes eaten by the laying hen, plus vitamin D, B vitamins, and heme iron, the form of iron most easily absorbed by your body. One large whole egg (50 g/1.8 ounce) has five grams fat (1.5 g satu- rated fat, 1.9 g monounsaturated fat, 0.7 g polyunsaturated fat), 212 mg cholesterol, 244 IU vitamin A (11 percent of the R DA for a woman, 9 percent * Values are for a whole egg. of the R DA for a man), 0.9 mg iron (5 percent of the R DA for a woman, 11 percent of the R DA for a man) and seven grams protein. The fat in the egg is all in the yolk. The protein is divided: four grams in the white, three grams in the yolk.
The Most Nutritious Way to Serve This Food With extra whites and fewer yolks to lower the fat and cholesterol per serving.
Diets That May Restrict or Exclude This Food Controlled-fat, low-cholesterol diet Low-protein diet
Buying This Food Look for: Eggs stored in the refrigerated dair y case. Check the date for freshness. NOTE : In 1998, the FDA and USDA Food Safety and Inspection Service (FSIS) proposed new rules that would require distributors to keep eggs refrigerated on the way to the store and require stores to keep eggs in a refrigerated case. The egg package must have a “refrigera- tion required” label plus safe-handling instructions on eggs that have not been treated to kill Salmonella. Look for: Eggs that fit your needs. Eggs are graded by the size of the yolk and the thick- ness of the white, qualities that affect appearance but not nutritional values. The higher the grade, the thicker the yolk and the thicker the white will be when you cook the egg. A Grade A A egg fried sunny side up will look much more attractive than a Grade B egg prepared the same way, but both will be equally nutritions. Egg sizes ( Jumbo, Extra large, Large, Medium, Small) are determined by how much the eggs weigh per dozen. The color of the egg’s shell depends on the breed of the hen that laid the egg and has nothing to do with the egg’s food value.
Storing This Food Store fresh eggs with the small end down so that the yolk is completely submerged in the egg white (which contains antibacterial properties, nature’s protection for the yolk—or a developing chick embryo in a fertilized egg). Never wash eggs before storing them: The water will make the egg shell more porous, allowing harmful microorganisms to enter. Store separated leftover yolks and whites in small, tightly covered containers in the refrigerator, where they may stay fresh for up to a week. Raw eggs are very susceptible to Salmonella and other bacterial contamination; discard any egg that looks or smells the least bit unusual. Refrigerate hard-cooked eggs, including decorated Easter eggs. They, too, are suscep- tible to Salmonella contamination and should never be left at room temperature.
Preparing This Food First, find out how fresh the eggs really are. The freshest ones are the eggs that sink and lie flat on their sides when submerged in cool water. These eggs can be used for any dish. By the time the egg is a week old, the air pocket inside, near the broad end, has expanded so that the broad end tilts up as the egg is submerged in cool water. The yolk and the white inside have begun to separate; these eggs are easier to peel when hard-cooked. A week or two later, the egg’s air pocket has expanded enough to cause the broad end of the egg to point straight up when you put the egg in water. By now the egg is runny and should be used in sauces where it doesn’t matter if it isn’t picture-perfect. After four weeks, the egg will float. Throw it away. Eggs are easily contaminated with Salmonella microorganisms that can slip through an intact shell. never eat or serve a dish or bever age containing r aw fr esh eggs. sa lmonella is destroyed by cooking eggs to an inter nal temper atur e of 145°f ; egg-milk dishes such as custar ds must be cooked to an inter nal temper atur e of 160°f. If you separate fresh eggs by hand, wash your hands thoroughly before touching other food, dishes, or cooking tools. When you have finished preparing raw eggs, wash your hands and all utensils thoroughly with soap and hot water. never stir cooked eggs with a utensil used on r aw eggs. When you whip an egg white, you change the structure of its protein molecules which unfold, breaking bonds between atoms on the same molecule and forming new bonds to atoms on adjacent molecules. The result is a network of protein molecules that hardens around air trapped in bubbles in the net. If you beat the whites too long, the foam will turn stiff enough to hold its shape even if you don’t cook it, but it will be too stiff to expand natu- rally if you heat it, as in a soufflé. When you do cook properly whipped egg white foam, the hot air inside the bubbles will expand. Ovalbumin, an elastic protein in the white, allows the bubble walls to bulge outward until they are cooked firm and the network is stabilized as a puff y soufflé. The bowl in which you whip the whites should be absolutely free of fat or grease, since the fat molecules will surround the protein molecules in the egg white and keep them from linking up together to form a puff y white foam. Eggs whites will react with metal ions from the surface of an aluminum bowl to form dark particles that discolor the egg-white foam. You can whip eggs successfully in an enamel or glass bowl, but they will do best in a copper bowl because copper ions bind to the egg and stabilize the foam.
What Happens When You Cook This Food When you heat a whole egg, its protein molecules behave exactly as they do when you whip an egg white. They unfold, form new bonds, and create a protein network, this time with molecules of water caught in the net. As the egg cooks, the protein network tightens, squeez- ing out moisture, and the egg becomes opaque. The longer you cook the egg, the tighter the network will be. If you cook the egg too long, the protein network will contract strongly enough to force out all the moisture. That is why overcooked egg custards run and why overcooked eggs are rubbery. If you mix eggs with milk or water before you cook them, the molecules of liquid will surround and separate the egg’s protein molecules so that it takes more energy (higher heat) to make the protein molecules coagulate. Scrambled eggs made with milk are softer than plain scrambled eggs cooked at the same temperature. When you boil an egg in its shell, the air inside expands and begins to escape through the shell as tiny bubbles. Sometimes, however, the force of the air is enough to crack the shell. Since there’s no way for you to tell in advance whether any particular egg is strong enough to resist the pressure of the bubbling air, the best solution is to create a safety vent by sticking a pin through the broad end of the egg before you start to boil it. Or you can slow the rate at which the air inside the shell expands by starting the egg in cold water and letting it warm up naturally as the water warms rather than plunging it cold into boiling water—which makes the air expand so quickly that the shell is virtually certain to crack. As the egg heats, a little bit of the protein in its white will decompose, releasing sulfur that links up with hydrogen in the egg, forming hydrogen sulfide, the gas that gives rot- ten eggs their distinctive smell. The hydrogen sulfide collects near the coolest part of the egg—the yolk. The yolk contains iron, which now displaces the hydrogen in the hydrogen sulfide to form a green iron-sulfide ring around the hard-cooked yolk.
How Other Kinds of Processing Affect This Food Egg substitutes. Fat-free, cholesterol-free egg substitutes are made of pasteurized egg whites, plus artificial or natural colors, flavors, and texturizers (food gums) to make the product look and taste like eggs, plus vitamins and minerals to produce the nutritional equivalent of a full egg. Pasteurized egg substitutes may be used without additional cooking, that is, in salad dressings and eggnog. Drying. Dried eggs have virtually the same nutritive value as fresh eggs. Always refrigerate dried eggs in an air- and moistureproof container. At room temperature, they will lose about a third of their vitamin A in six months.
Medical Uses and/or Benefits Protein source. The protein in eggs, like protein from all animal foods, is complete. That is, protein from animal foods provides all the essential amino acids required by human beings. In fact, the protein from eggs is so well absorbed and utilized by the human body that it is considered the standard by which all other dietary protein is measured. On a scale known as biological value, eggs rank 100 ; milk, 93; beef and fish, 75; and poultry, 72. Vision protection. The egg yolk is a rich source of the yellow-orange carotenoid pigments lutein and zeaxanthin. Both appear to play a role in protecting the eyes from damaging ultraviolet light, thus reducing the risk of cataracts and age-related macular degeneration, a leading cause of vision of loss in one-third of all Americans older than 75. Just 1.3 egg yolks a day appear to increase blood levels of lutein and zeaxanthin by up to 128 percent. Perhaps as a result, data released by the National Eye Institute’s 6,000-person Beaver Dam ( Wisconsin) Eye Study in 2003 indicated that egg consumption was inversely associated with cataract risk in study participants who were younger than 65 years of age when the study started. The relative risk of cataracts was 0.4 for people in the highest category of egg consumption, compared to a risk of 1.0 for those in the lowest category. External cosmetic effects. Beaten egg whites can be used as a facial mask to make your skin look smoother temporarily. The mask works because the egg proteins constrict as they dry on your face, pulling at the dried layer of cells on top of your skin. When you wash off the egg white, you also wash off some of these loose cells. Used in a rinse or shampoo, the pro- tein in a beaten raw egg can make your hair look smoother and shinier temporarily by filling in chinks and notches on the hair shaft.
Adverse Effects Associated with This Food Increased risk of cardiovascular disease. Although egg yolks are high in cholesterol, data from several recent studies suggest that eating eggs may not increase the risk of heart disease. In 2003, a report from a 14-year, 177,000-plus person study at the Harvard School of Public Health showed that people who eat one egg a day have exactly the same risk of heart disease as those who eat one egg or fewer per week. A similar report from the Multiple R isk Factor Intervention Trial showed an inverse relationship between egg consumption and cholesterol levels—that is, people who ate more eggs had lower cholesterol levels. Nonetheless, in 2006 the National Heart, Lung, and Blood Institute still recommends no more than four egg yolks a week (including the yolk in baked goods) for a heart-healthy diet. The American Heart Association says consumers can have one whole egg a day if they limit cholesterol from other sources to the amount suggested by the National Cholesterol Education Project following the Step I and Step II diets. (Both groups permit an unlimited number of egg whites.) The Step I diet provides no more than 30 percent of total daily calories from fat, no more than 10 percent of total daily calories from saturated fat, and no more than 300 mg of cholesterol per day. It is designed for healthy people whose cholesterol is in the range of 200 –239 mg/dL. The Step II diet provides 25– 35 percent of total calories from fat, less than 7 percent of total calories from saturated fat, up to 10 percent of total calories from polyunsaturated fat, up to 20 percent of total calories from monounsaturated fat, and less than 300 mg cho- lesterol per day. This stricter regimen is designed for people who have one or more of the following conditions: • Existing cardiovascular disease • High levels of low-density lipoproteins (LDLs, or “bad” cholesterol) or low levels of high-density lipoproteins (HDLs, or “good” cholesterol) • Obesity • Type 1 diabetes (insulin-dependent diabetes, or diabetes mellitus) • Metabolic syndrome, a.k.a. insulin resistance syndrome, a cluster of risk fac- tors that includes type 2 diabetes (non-insulin-dependent diabetes) Food poisoning. Raw eggs (see above) and egg-rich foods such as custards and cream pies are excellent media for microorganisms, including the ones that cause food poisoning. To protect yourself against egg-related poisoning, always cook eggs thoroughly: poach them five minutes over boiling water or boil at least seven minutes or fry two to three minutes on each side (no runny center) or scramble until firm. Bread with egg coating, such as French toast, should be cooked crisp. Custards should be firm and, once cooked, served very hot or refrigerated and served very cold. Allergic reaction. According to the Merck Manual, eggs are one of the 12 foods most likely to trigger the classic food allergy symptoms: hives, swelling of the lips and eyes, and upset stomach. The others are berries (blackberries, blueberries, raspberries, strawberries), choco- late, corn, fish, legumes (green peas, lima beans, peanuts, soybeans), milk, nuts, peaches, pork, shellfish, and wheat (see wheat cer ea ls).
Food/Drug Interactions Sensitivity to vaccines. Live-virus measles vaccine, live-virus mumps vaccine, and the vac- cines for influenza are grown in either chick embryo or egg culture. They may all contain minute residual amounts of egg proteins that may provoke a hypersensitivity reaction in people with a history of anaphylactic reactions to eggs (hives, swelling of the mouth and throat, difficulty breathing, a drop in blood pressure, or shock).... eggs
Nutritional Profile Energy value (calories per serving): Moderate Protein: High Fat: Low to moderate Saturated fat: Low to moderate Cholesterol: Moderate Carbohydrates: Low Fiber: None Sodium: Low (fresh fish) High (some canned or salted fish) Major vitamin contribution: Vitamin A, vitamin D Major mineral contribution: Iodine, selenium, phosphorus, potassium, iron, calcium
About the Nutrients in This Food Like meat, poultry, milk, and eggs, fish are an excellent source of high- quality proteins with sufficient amount of all the essential amino acids. While some fish have as much or more fat per serving than some meats, the fat content of fish is always lower in saturated fat and higher in unsaturated fats. For example, 100 g/3.5 ounce cooked pink salmon (a fatty fish) has 4.4 g total fat, but only 0.7 g saturated fat, 1.2 g monounsaturated fat, and 1.7 g polyunsaturated fat; 100 g/3.5 ounce lean top sirloin has four grams fat but twice as much saturated fat (1.5 g), plus 1.6 g monounsatu- rated fat and only 0.2 g polyunsaturated fat. Omega-3 Fatty Acid Content of Various Fish (Continued) Fish Grams/ounce Rainbow trout 0.30 Lake whitefish 0.25 Source: “Food for t he Heart,” American Health, April 1985. Fish oils are one of the few natural food sources of vitamin D. Salmon also has vita- min A derived from carotenoid pigments in the plants eaten by the fish. The soft bones in some canned salmon and sardines are an excellent source of calcium. CAUTION: do not eat the bones in r aw or cook ed fish. the only bones consider ed edible ar e those in the canned products.
The Most Nutritious Way to Serve This Food Cooked, to kill parasites and potentially pathological microorganisms living in raw fish. Broiled, to liquify fat and eliminate the fat-soluble environmental contaminants found in some freshwater fish. With the soft, mashed, calcium-rich bones (in canned salmon and canned sardines).
Diets That May Restrict or Exclude This Food Low-purine (antigout) diet Low-sodium diet (canned, salted, or smoked fish)
Buying This Food Look for: Fresh-smelling whole fish with shiny skin; reddish pink, moist gills; and clear, bulging eyes. The flesh should spring back when you press it lightly. Choose fish fillets that look moist, not dry. Choose tightly sealed, solidly frozen packages of frozen fish. In 1998, the FDA /National Center for Toxicological Research released for testing an inexpensive indicator called “Fresh Tag.” The indicator, to be packed with seafood, changes color if the product spoils. Avoid: Fresh whole fish whose eyes have sunk into the head (a clear sign of aging); fillets that look dry; and packages of frozen fish that are stained (whatever leaked on the package may have seeped through onto the fish) or are coated with ice crystals (the package may have defrosted and been refrozen).
Storing This Food Remove fish from plastic wrap as soon as you get it home. Plastic keeps out air, encouraging the growth of bacteria that make the fish smell bad. If the fish smells bad when you open the package, throw it out. Refrigerate all fresh and smoked fish immediately. Fish spoils quickly because it has a high proportion of polyunsaturated fatty acids (which pick up oxygen much more easily than saturated or monounsaturated fatty acids). Refrigeration also slows the action of microorgan- isms on the surface of the fish that convert proteins and other substances to mucopolysac- charides, leaving a slimy film on the fish. Keep fish frozen until you are ready to use it. Store canned fish in a cool cabinet or in a refrigerator (but not the freezer). The cooler the temperature, the longer the shelf life.
Preparing This Food Fresh fish. Rub the fish with lemon juice, then rinse it under cold running water. The lemon juice (an acid) will convert the nitrogen compounds that make fish smell “fishy” to compounds that break apart easily and can be rinsed off the fish with cool running water. R insing your hands in lemon juice and water will get rid of the fishy smell after you have been preparing fresh fish. Frozen fish. Defrost plain frozen fish in the refrigerator or under cold running water. Pre- pared frozen fish dishes should not be thawed before you cook them since defrosting will make the sauce or coating soggy. Salted dried fish. Salted dried fish should be soaked to remove the salt. How long you have to soak the fish depends on how much salt was added in processing. A reasonable average for salt cod, mackerel, haddock (finnan haddie), or herring is three to six hours, with two or three changes of water. When you are done, clean all utensils thoroughly with hot soap and hot water. Wash your cutting board, wood or plastic, with hot water, soap, and a bleach-and-water solution. For ultimate safety in preventing the transfer of microorganisms from the raw fish to other foods, keep one cutting board exclusively for raw fish, meats, and poultry, and a second one for everything else. Finally, don’t forget to wash your hands.
What Happens When You Cook This Food Heat changes the structure of proteins. It denatures the protein molecules so that they break apart into smaller fragments or change shape or clump together. These changes force moisture out of the tissues so that the fish turns opaque. The longer you cook fish, the more moisture it will lose. Cooked fish flakes because the connective tissue in fish “melts” at a relatively low temperature. Heating fish thoroughly destroys parasites and microorganisms that live in raw fish, making the fish safer to eat.
How Other Kinds of Processing Affect This Food Marinating. Like heat, acids coagulate the proteins in fish, squeezing out moisture. Fish marinated in citrus juices and other acids such as vinegar or wine has a firm texture and looks cooked, but the acid bath may not inactivate parasites in the fish. Canning. Fish is naturally low in sodium, but can ned fish often contains enough added salt to make it a high-sodium food. A 3.5-ounce ser ving of baked, fresh red salmon, for example, has 55 mg sodium, while an equal ser ving of regular can ned salmon has 443 mg. If the fish is can ned in oil it is also much higher in calories than fresh fish. Freezing. When fish is frozen, ice cr ystals form in the flesh and tear its cells so that mois- ture leaks out when the fish is defrosted. Commercial flash-freezing offers some protec- tion by freezing the fish so fast that the ice cr ystals stay small and do less damage, but all defrosted fish tastes drier and less palatable than fresh fish. Freezing slows but does not stop the oxidation of fats that causes fish to deteriorate. Curing. Fish can be cured (preser ved) by smoking, dr ying, salting, or pickling, all of which coagulate the muscle tissue and prevent microorganisms from growing. Each method has its own particular drawbacks. Smoking adds potentially carcinogenic chemicals. Dr ying reduces the water content, concentrates the solids and nutrients, increases the calories per ounce, and raises the amount of sodium.
Medical Uses and/or Benefits Protection against cardiovascular disease. The most important fats in fish are the poly- unsaturated acids k nown as omega-3s. These fatt y acids appear to work their way into heart cells where they seem to help stabilize the heart muscle and prevent potentially fatal arrhythmia (irregular heartbeat). A mong 85,000 women in the long-run n ing Nurses’ Health Study, those who ate fatt y fish at least five times a week were nearly 50 percent less likely to die from heart disease than those who ate fish less frequently. Similar results appeared in men in the equally long-run n ing Physicians’ Health Study. Some studies suggest that people may get similar benefits from omega-3 capsules. Researchers at the Consorzio Mario Negri Sud in Santa Maria Imbaro ( Italy) say that men given a one-gram fish oil capsule once a day have a risk of sudden death 42 percent lower than men given placebos ( “look-alike” pills with no fish oil). However, most nutrition scientists recom- mend food over supplements. Omega-3 Content of Various Food Fish Fish* (3 oz.) Omega-3 (grams) Salmon, Atlantic 1.8 Anchovy, canned* 1.7 Mackerel, Pacific 1.6 Salmon, pink, canned* 1.4 Sardine, Pacific, canned* 1.4 Trout, rainbow 1.0 Tuna, white, canned* 0.7 Mussels 0.7 * cooked, wit hout sauce * drained Source: Nat ional Fisheries Inst itute; USDA Nut rient Data Laborator y. Nat ional Nut ri- ent Database for Standard Reference. Available online. UR L : http://w w w.nal.usda. gov/fnic/foodcomp/search /.
Adverse Effects Associated with This Food Allergic reaction. According to the Merck Manual, fish is one of the 12 foods most likely to trigger classic food allergy symptoms: hives, swelling of the lips and eyes, and upset stom- ach. The others are berries (blackberries, blueberries, raspberries, strawberries), chocolate, corn, eggs, legumes (green peas, lima beans, peanuts, soybeans), milk, nuts, peaches, pork, shellfish, and wheat (see wheat cer ea ls). NOTE : Canned tuna products may contain sulfites in vegetable proteins used to enhance the tuna’s flavor. People sensitive to sulfites may suf- fer serious allergic reactions, including potentially fatal anaphylactic shock, if they eat tuna containing sulfites. In 1997, tuna manufacturers agreed to put warning labels on products with sulfites. Environmental contaminants. Some fish are contaminated with methylmercury, a compound produced by bacteria that chemically alters naturally occurring mercury (a metal found in rock and soil) or mercury released into water through industrial pollution. The methylmer- cury is absorbed by small fish, which are eaten by larger fish, which are then eaten by human beings. The larger the fish and the longer it lives the more methylmercury it absorbs. The measurement used to describe the amount of methylmercury in fish is ppm (parts per mil- lion). Newly-popular tilapia, a small fish, has an average 0.01 ppm, while shark, a big fish, may have up to 4.54 ppm, 450 times as much. That is a relatively small amount of methylmercur y; it will soon make its way harmlessly out of the body. But even small amounts may be hazardous during pregnancy because methylmercur y targets the developing fetal ner vous system. Repeated studies have shown that women who eat lots of high-mercur y fish while pregnant are more likely to deliver babies with developmental problems. As a result, the FDA and the Environ men- tal Protection Agency have now warned that women who may become pregnant, who are pregnant, or who are nursing should avoid shark, swordfish, king mackerel, and tilefish, the fish most likely to contain large amounts of methylmercur y. The same prohibition applies to ver y young children; although there are no studies of newborns and babies, the young brain continues to develop after birth and the logic is that the prohibition during pregnancy should extend into early life. That does not mean no fish at all should be eaten during pregnancy. In fact, a 2003 report in the Journal of Epidemiology and Community Health of data from an 11,585-woman study at the University of Bristol (England) shows that women who don’t eat any fish while pregnant are nearly 40 percent more likely to deliver low birth-weight infants than are women who eat about an ounce of fish a day, the equivalent of 1/3 of a small can of tuna. One theory is that omega-3 fatty acids in the fish may increase the flow of nutrient-rich blood through the placenta to the fetus. University of Southern California researchers say that omega-3s may also protect some children from asthma. Their study found that children born to asthmatic mothers who ate oily fish such as salmon at least once a month while pregnant were less likely to develop asthma before age five than children whose asthmatic pregnant mothers never ate oily fish. The following table lists the estimated levels of mercury in common food fish. For the complete list of mercury levels in fish, click onto www.cfsan.fda.gov/~frf/sea-mehg.html. Mercury Levels in Common Food Fish Low levels (0.01– 0.12 ppm* average) Anchovies, butterfish, catfish, clams, cod, crab (blue, king, snow), crawfish, croaker (Atlantic), flounder, haddock, hake, herring, lobster (spiny/Atlantic) mackerel, mul- let, ocean perch, oysters, pollock, salmon (canned/fresh frozen), sardines, scallops, shad (American), shrimp, sole, squid, tilapia, trout (freshwater), tuna (canned, light), whitefish, whiting Mid levels (0.14 – 0.54 ppm* average) Bass (salt water), bluefish, carp, croaker ( Pacific), freshwater perch, grouper, halibut, lobster (Northern A merican), mackerel (Spanish), marlin, monkfish, orange roughy, skate, snapper, tilefish (Atlantic), tuna (can ned albacore, fresh/frozen), weakfish/ sea trout High levels (0.73 –1.45 ppm* average) King mackerel, shark, swordfish, tilefish * ppm = parts per million, i.e. parts of mercur y to 1,000,000 parts fish Source: U.S. Food and Drug Administ rat ion, Center for Food Safet y and Applied Nut rit ion, “Mercur y Levels in Commercial Fish and Shellfish.” Available online. UR L : w w w.cfsan.fda. gov/~frf/sea-mehg.ht ml. Parasitical, viral, and bacterial infections. Like raw meat, raw fish may carry various pathogens, including fish tapeworm and flukes in freshwater fish and Salmonella or other microorganisms left on the fish by infected foodhandlers. Cooking the fish destroys these organisms. Scombroid poisoning. Bacterial decomposition that occurs after fish is caught produces a his- taminelike toxin in the flesh of mackerel, tuna, bonito, and albacore. This toxin may trigger a number of symptoms, including a flushed face immediately after you eat it. The other signs of scombroid poisoning—nausea, vomiting, stomach pain, and hives—show up a few minutes later. The symptoms usually last 24 hours or less.
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 such as pickled herring, which is high in tyramine, while you are taking an M AO inhibitor, your body may not be able to eliminate the tyramine and the result may be a hypertensive crisis.... fish
Nutritional Profile Energy value (calories per serving): Moderate Protein: High Fat: Low Saturated fat: High Cholesterol: Moderate Carbohydrates: None Fiber: None Sodium: Low Major vitamin contribution: B vitamins Major mineral contribution: Iron, zinc
About the Nutrients in This Food Like other animal foods, game meat has high-quality proteins with suf- ficient amounts of all the essential amino acids. Some game meat has less fat, saturated fat, and cholesterol than beef. All game meat is an excellent source of B vitamins, plus heme iron, the form of iron most easily absorbed by your body, and zinc. For example, one four-ounce serving of roast bison has 28 g protein, 2.7 g fat (1.04 g saturated fat), 93.7 mg cholesterol, 3.88 mg iron (25.8 percent of the R DA for a woman of childbearing age), and 4.1 mg zinc (27 percent of the R DA for a man). The Nutrients in Roasted Game Meat (4-ounce serving)
The Most Nutritious Way to Serve This Food With a food rich in vitamin C. Vitamin C increases the absorption of iron.
Diets That May Restrict or Exclude This Food Low-protein diet (for kidney disease)
Buying This Food In American markets, game meats are usually sold frozen. Choose a package with no leaks or stains to suggest previous defrosting.
Storing This Food Keep frozen game meat well wrapped in the freezer until you are ready to use it. The packaging protects the meat from oxygen that can change its pigments from reddish to brown. Freezing prolongs the freshness of the meat by slowing the natural multiplication of bacteria that digest proteins and other substances on the surface, converting them to a slimy film. The bacteria also change the meat’s sulfur-containing amino acids methionine and cystine into smelly chemicals called mercaptans. When the mercaptans combine with myoglobin, they produce the greenish pigment that gives spoiled meat its characteristic unpleasant appearance. Large cuts of game meat can be safely frozen, at 0°F, for six months to a year.
Preparing This Food Defrost the meat in the refrigerator to protect it from spoilage. Trim the meat to dispose of all visible fat, thus reducing the amount of fat and cholesterol in each serving. When you are done, clean all utensils thoroughly with hot soap and hot water. Wash your cutting board, wood or plastic, with hot water, soap, and a bleach-and-water solution. For ultimate safety in preventing the transfer of microorganisms from the raw meat to other foods, keep one cutting board exclusively for raw meats, fish, and poultry, and a second one for everything else. Finally, don’t forget to wash your hands.
What Happens When You Cook This Food Cooking changes the way meat looks and tastes, alters its nutritional value, makes it safer, and extends its shelf life. Browning meat before you cook it does not “seal in the juices,” but it does change the flavor by caramelizing proteins and sugars on the surface. Because meat’s only sugars are the Game Meat
63 small amounts of glycogen in muscle tissue, we add sugars in marinades or basting liquids that may also contain acids (vinegar, lemon juice, wine) to break down muscle fibers and tenderize the meat. (NOTE : Browning has one minor nutritional drawback. It breaks amino acids on the surface of the meat into smaller compounds that are no longer useful proteins.) When meat is heated, it loses water and shrinks. Its pigments, which combine with oxygen, are denatured (broken into fragments) by the heat. They turn brown, the natural color of well-done meat. At the same time, the fats in the meat are oxidized, a reaction that produces a characteristic warmed-over flavor when the cooked meat is refrigerated and then reheated. Cooking and storing the meat under a blanket of antioxidants—catsup or a gravy made of tomatoes, peppers and other vitamin-C rich vegetables—reduces fat oxidation and lessens the warmed-over flavor. Meat reheated in a microwave oven is also less likely to taste warmed-over.
How Other Kinds of Processing Affect This Food Aging. Hanging fresh meat exposed to air in a cold room evaporates moisture and shrinks the meat slightly. At the same time, bacterial action on the surface of the meat breaks down proteins, producing an “aged” flavor. (See below, Food/drug interactions.) Curing. Salt-curing preserves meat through osmosis, the physical reaction in which liquids flow across a membrane, such as the wall of a cell, from a less dense to a more dense solu- tion. The salt or sugar used in curing dissolve in the liquid on the surface of the meat to make a solution that is more dense than the liquid inside the cells of the meat. Water flows out of the meat and out of the cells of any microorganisms living on the meat, killing the micro-organisms and protecting the meat from bacterial damage. Salt-cured meat is higher in sodium than fresh meat. Smoking. Hanging fresh meat over an open fire slowly dries the meat, kills microorgan- isms on its surface, and gives the meat a rich, smoky flavor. The flavor varies with the wood used in the fire. Meats smoked over an open fire are exposed to carcinogenic chemicals in the smoke, including a-benzopyrene. Artificial smoke flavoring is commercially treated to remove tar and a-benzopyrene.
Medical Uses and/or Benefits Treating and/or preventing iron deficiency. Without meat in the diet, it is virtually impossible for an adult woman to meet her iron requirement without supplements.
Adverse Effects Associated with This Food Increased risk of cardiovascular disease. Like all foods from animals, game meats are a source of cholesterol. To reduce the risk of heart disease, the National Cholesterol Education Project recommends following the Step I and Step II diets. The Step I diet provides no more than 30 percent of total daily calories from fat, no more than 10 percent of total daily calories from saturated fat, and no more than 300 mg of cholesterol per day. It is designed for healthy people whose cholesterol is in the range of 200 –239 mg/dL. The Step II diet provides 25– 35 percent of total calories from fat, less than 7 percent of total calories from saturated fat, up to 10 percent of total calories from polyunsaturated fat, up to 20 percent of total calories from monounsaturated fat, and less than 300 mg cho- lesterol per day. This stricter regimen is designed for people who have one or more of the following conditions: • Existing cardiovascular disease • High levels of low-density lipoproteins (LDLs, or “bad” cholesterol) or low levels of high-density lipoproteins (HDLs, or “good” cholesterol) • Obesity • Type 1 diabetes (insulin-dependent diabetes, or diabetes mellitus) • Metabolic syndrome, a.k.a. insulin resistance syndrome, a cluster of risk fac- tors that includes type 2 diabetes (non-insulin-dependent diabetes) Food-borne illness. Improperly cooked meat contaminated with E. coli O157:H7 has been linked to a number of fatalities in several parts of the United States. In addition, meat con- taminated with other bacteria, viruses, or parasites poses special problems for people with a weakened immune system: the very young, the very old, cancer chemotherapy patients, and people with HIV. Cooking meat to an internal temperature of 140°F should destroy Salmo- nella and Campylobacter jejuni; to 165°F, E. coli, and to 212°F, Listeria monocytogenes. Decline in kidney function. Proteins are nitrogen compounds. When metabolized, they yield ammonia that is excreted through the kidneys. In laboratory animals, a sustained high-pro- tein diet increases the flow of blood through the kidneys, accelerating the natural age-related decline in kidney function. Some experts suggest that this may also occur in human beings.
Food/Drug Interactions Monoamine oxidase (MAO) inhibitors. Meat “tenderized” with papaya or a papain powder can interact with the class of antidepressant drugs known as monoamine oxidase inhibi- tors. Papain meat tenderizers work by breaking up the long chains of protein molecules. One by-product of this process is tyramine, a substance that constructs blood vessels and raises blood pressure. M AO inhibitors inactivate naturally occurring enzymes in your body that metabolize tyramine. If you eat a food such as papain-tenderized meat, which is high in 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.... game meat
Nutritional Profile Energy value (calories per serving): Low Protein: Moderate Fat: Low Saturated fat: Low Cholesterol: None Carbohydrates: High Fiber: Moderate Sodium: Moderate Major vitamin contribution: Vitamin C Major mineral contribution: Potassium
About the Nutrients in This Food Beets are roots, high-carbohydrate foods that provide sugars, starch, and small amounts of dietary fiber, insoluble cellulose in the skin, and soluble pectins in the flesh. Beets are also a good source of the B vitamin folate. One-half cup cooked fresh beets has one gram of dietar y fiber and 68 mcg folate (17 percent of the R DA).
The Most Nutritious Way to Serve This Food Cooked, to dissolve the stiff cell walls and make the nutrients inside available.
Diets That May Restrict or Exclude This Food Anti-kidney-stone diet Low-sodium diet
Buying This Food Look for: Smooth round globes with fresh, crisp green leaves on top. Avoid: Beets with soft spots or blemishes that suggest decay underneath.
Storing This Food Protect the nutrients in beets by storing the vegetables in a cool place, such as the vegetable crisper in your refrigerator. When stored, the beet root converts its starch into sugars; the longer it is stored, the sweeter it becomes. Remove the green tops from beets before storing and store the beet greens like other leaf y vegetables, in plastic bags in the refrigerator to keep them from drying out and losing vitamins (also see gr eens). Use both beets and beet greens within a week.
Preparing This Food Scrub the globes with a vegetable brush under cold running water. You can cook them whole or slice them. Peel before (or after) cooking.
What Happens When You Cook This Food Betacyamin and betaxanthin, the red betalain pigments in beets, are water-soluble. (That’s why borscht is a scarlet soup.) Betacyanins and betaxanthins turn more intensely red when you add acids; think of scarlet sweet-and-sour beets in lemon juice or vinegar with sugar. They turn slightly blue in a basic (alkaline) solution such as baking soda and water. Like carrots, beets have such stiff cell walls that it is hard for the human digestive tract to extract the nutrients inside. Cooking will not soften the cellulose in the beet’s cell walls, but it will dissolve enough hemicellulose so that digestive juices are able to penetrate. Cook- ing also activates flavor molecules in beets, making them taste better.
How Other Kinds of Processing Affect This Food Canning. Beets lose neither their color nor their texture in canning.
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 continu- ing 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. Possible lower risk of heart attack. In the spring of 1998, an analysis of data from the records of more than 80,000 women enrolled in the long-running Nurses’ Health Study at Harvard School of Public Health/Brigham and Women’s Hospital, in Boston, demonstrated that a diet providing more than 400 mcg folate and 3 mg vitamin B6 daily, either from food or supple- ments, might reduce a woman’s risk of heart attack by almost 50 percent. Although men were not included in the study, the results were 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 diseases 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 verif y whether taking folic acid supplements reduces the risk of cardiovascular disease.
Adverse Effects Associated with This Food Pigmented urine and feces. The ability to metabolize betacyanins and be taxanthins is a genetic trait. People with two recessive genes for this trait cannot break down these red pig- ments, which will be excreted, bright red, in urine. Eating beets can also turn feces red, but it will not cause a false-positive result in a test for occult blood in the stool. Nitrosamine formation. Beets, celery, eggplant, lettuce, radishes, spinach, and collard and turnip greens contain nitrates that convert naturally into nitrites in your stomach—where some of the nitrites combine with amines to form nitrosamines, some of which are known carcinogens. This natural chemical reaction presents no known problems for a healthy adult. However, when these vegetables are cooked and left standing for a while at room tempera- ture, microorganisms that convert nitrates to nitrites begin to multiply, and the amount of nitrites in the food rises. The resulting higher-nitrite foods may be dangerous for infants (see spinach).... beets
Nutritional Profile Energy value (calories per serving): Moderate to high Protein: Moderate to high Fat: Low to high Saturated fat: High Cholesterol: Low to high Carbohydrates: Low Fiber: None Sodium: High Major vitamin contribution: Vitamin A, vitamin D, B vitamins Major mineral contribution: Calcium
About the Nutrients in This Food Cheese making begins when Lactobacilli and/or Streptococci bacteria are added to milk. The bacteria digest lactose (milk sugar) and release lactic acid, which coagulates casein (milk protein) into curds. Rennet (gastric enzymes extracted from the stomach of calves) is added, and the mixture is put aside to set. The longer the curds are left to set, the firmer the cheese will be. When the curds are properly firm, they are pressed to squeeze out the whey (liquid) and cooked. Cooking evaporates even more liquid and makes the cheese even firmer.* At this point, the product is “fresh” or “green” cheese: cottage cheese, cream cheese, farmer cheese. Making “ripe” cheese requires the addition of salt to pull out more moisture and specific organisms, such as Penicil- lium roquefort for Roquefort cheese, blue cheese, and Stilton, or Penicillium cambembert for Camembert and Brie. The nutritional value of cheese is similar to the milk from which it is made. All cheese is a good source of high quality proteins with sufficient amounts of all the essential amino acids. Cheese is low to high in fat, mod- erate to high in cholesterol. * Natural cheese is cheese made direct ly from milk. Processed cheese is natural cheese melted and combined wit h emulsifiers. Pasteurized process cheese foods contain ingredients t hat allow t hem to spread smoot hly; t hey are lower in fat and higher in moisture t han processed cheese. Cholesterol and Saturated Fat Content of Selected Cheeses Mozzarella Source: USDA, Nutritive Value of Foods, Home and Garden Bullet in No. 72 (USDA, 1989). All cheeses, except cottage cheese, are good sources of vitamin A. Orange and yellow cheeses are colored with carotenoid pigments, including bixin (the carotenoid pigment in annatto) and synthetic beta-carotene. Hard cheeses are an excellent source of calcium; softer cheeses are a good source; cream cheese and cottage cheese are poor sources. The R DA for calcium is 1,000 mg for a woman, 1,200 mg for a man, and 1,500 mg for an older woman who is not on hormone- replacement therapy. All cheese, unless otherwise labeled, is high in sodium.
| Calcium Content of Cheese | ||
| Cheese | Serving | Calcium (mg) |
| Blue | oz. | 150 |
| Camembert | wedge | 147 |
| Cheddar | oz. | 204 |
| Cottage cheese | ||
| creamed | cup | 135 |
| uncreamed | cup | 46 |
| Muenster | oz. | 203 |
| Pasteurized processed American | oz. | 174 |
| Parmesan grated | tbsp. | 69 |
| Provolone | oz. | 214 |
| Swiss | oz. | 272 |
The Most Nutritious Way to Serve This Food With grains, bread, noodles, beans, nuts, or vegetables to add the essential amino acids miss- ing from these foods, “complete” their proteins, and make them more nutritionally valuable.
Diets That May Restrict or Exclude This Food Antiflatulence diet Controlled-fat, low-cholesterol diet Lactose- and galactose-free diet (lactose, a disaccharide [double sugar] is composed of one unit of galactose and one unit of glucose) Low-calcium diet (for patients with kidney disease) Sucrose-free diet (processed cheese)
Buying This Food Look for: Cheese stored in a refrigerated case. Check the date on the package. Avoid: Any cheese with mold that is not an integral part of the food.
Storing This Food Refrigerate all cheese except unopened canned cheeses (such as Camembert in tins) or grated cheeses treated with preservatives and labeled to show that they can be kept outside the refrigerator. Some sealed packages of processed cheeses can be stored at room temperature but must be refrigerated once the package is opened. Wrap cheeses tightly to protect them from contamination by other microorganisms in the air and to keep them from drying out. Well-wrapped, refrigerated hard cheeses that have not been cut or sliced will keep for up to six months; sliced hard cheeses will keep for about two weeks. Soft cheeses (cottage cheese, ricotta, cream cheese, and Neufchatel) should be used within five to seven days. Use all packaged or processed cheeses by the date stamped on the package. Throw out moldy cheese (unless the mold is an integral part of the cheese, as with blue cheese or Stilton).
Preparing This Food To grate cheese, chill the cheese so it won’t stick to the grater. The molecules that give cheese its taste and aroma are largely immobilized when the cheese is cold. When serving cheese with fruit or crackers, bring it to room temperature to activate these molecules.
What Happens When You Cook This Food Heat changes the structure of proteins. The molecules are denatured, which means that they may be broken into smaller fragments or change shape or clump together. All of these changes may force moisture out of the protein tissue, which is why overcooked cheese is often stringy. Whey proteins, which do not clump or string at low temperatures, contain the sulfur atoms that give hot or burned cheese an unpleasant “cooked” odor. To avoid both strings and an unpleasant odor, add cheese to sauces at the last minute and cook just long enough to melt the cheese.
How Other Kinds of Processing Affect This Food Freezing. All cheese loses moisture when frozen, so semisoft cheeses will freeze and thaw better than hard cheeses, which may be crumbly when defrosted. Drying. The less moisture cheese contains, the less able it is to support the growth of organ- isms like mold. Dried cheeses keep significantly longer than ordinary cheeses.
Medical Uses and/or Benefits To strengthen bones and reduce age-related loss of bone density. High-calcium foods protect bone density. The current recommended dietary allowance (R DA) for calcium is still 800 mg for adults 25 and older, but a 1984 National Institutes of Health (NIH) Conference advisory stated that lifelong protection for bones requires an R DA of 1,000 mg for healthy men and women age 25 to 50 ; 1,000 mg for older women using hormone replacement therapy; and 1,500 mg for older women who are not using hormones, and these recommendations have been confirmed in a 1994 NIH Consensus Statement on optimal calcium intake. A diet with adequate amounts of calcium-rich foods helps protect bone density. Low-fat and no-fat cheeses provide calcium without excess fat and cholesterol. Protection against tooth decay. Studies at the University of Iowa (Iowa City) Dental School confirm that a wide variety of cheeses, including aged cheddar, Edam, Gouda, Monterey Jack, Muenster, mozzarella, Port Salut, Roquefort, Romano, Stilton, Swiss, and Tilsit—limit the tooth decay ordinarily expected when sugar becomes trapped in plaque, the sticky film on tooth surfaces where cavity-causing bacteria flourish. In a related experiment using only cheddar cheese, people who ate cheddar four times a day over a two-week period showed a 20 percent buildup of strengthening minerals on the surface of synthetic toothlike material attached to the root surfaces of natural teeth. Protection against periodontal disease. A report in the January 2008 issue of the Journal of Periodontology suggests that consuming adequate amounts of dairy products may reduce the risk of developing periodontal disease. Examining the dental health of 942 subjects ages 40 to 79, researchers at Kyushu University, in Japan, discovered that those whose diets regularly included two ounces (55 g) of foods containing lactic acid (milk, cheese, and yogurt) were significantly less likely to have deep “pockets” (loss of attachment of tooth to gum) than those who consumed fewer dairy products.
Adverse Effects Associated with This Food Increased risk of heart disease. Like other foods from animals, cheese is a source of choles- terol and saturated fats, which increase the amount of cholesterol circulating in your blood and raise your risk of heart disease. To reduce the risk of heart disease, the USDA /Health and Human Services Dietary Guidelines for Americans recommends limiting the amount of cholesterol in your diet to no more than 300 mg a day. The guidelines also recommend limit- ing the amount of fat you consume to no more than 30 percent of your total calories, while holding your consumption of saturated fats to more than 10 percent of your total calories (the calories from saturated fats are counted as part of the total calories from fat). Food poisoning. Cheese made from raw (unpasteurized) milk may contain hazardous microorganisms, including Salmonella and Listeria. Salmonella causes serious gastric upset; Lis- teria, a flulike infection, encephalitis, or blood infection. Both may be life-threatening to the very young, the very old, pregnant women, and those whose immune systems are weakened either by illness (such as AIDS) or drugs (such as cancer chemotherapy). In 1998, the Federal Centers for Disease Control (CDC) released data identif ying Listeria as the cause of nearly half the reported deaths from food poisoning. Allergy to milk proteins. Milk is one of the foods most frequently implicated as a cause of allergic reactions, particularly upset stomach. However, in many cases the reaction is not a true allergy but the result of lactose intolerance (see below). Lactose intolerance. Lactose intolerance—the inability to digest the sugar in milk—is an inherited metabolic deficiency that affects two thirds of all adults, including 90 to 95 percent of all Orientals, 70 to 75 percent of all blacks, and 6 to 8 percent of Caucasians. These people do not have sufficient amounts of lactase, the enzyme that breaks the disaccharide lactose into its easily digested components, galactose and glucose. When they drink milk, the undi- gested sugar is fermented by bacteria in the gut, causing bloating, diarrhea, flatulence, and intestinal discomfort. Some milk is now sold with added lactase to digest the lactose and make the milk usable for lactase-deficient people. In making cheese, most of the lactose in milk is broken down into glucose and galactose. There is very little lactose in cheeses other than the fresh ones—cottage cheese, cream cheese, and farmer cheese. Galactosemia. Galactosemia is an inherited metabolic disorder in which the body lacks the enzymes needed to metabolize galactose, a component of lactose. Galactosemia is a reces- sive trait; you must receive the gene from both parents to develop the condition. Babies born with galactosemia will fail to thrive and may develop brain damage or cataracts if they are given milk. To prevent this, children with galactosemia are usually kept on a protective milk- free diet for several years, until their bodies have developed alternative pathways by which to metabolize galactose. Pregnant women who are known carriers of galactosemia may be advised to give up milk and milk products while pregnant lest the unmetabolized galactose in their bodies cause brain damage to the fetus (damage not detectable by amniocentesis). Genetic counseling is available to identif y galactosemia carriers and assess their chances of producing a baby with the disorder. Penicillin sensitivity. People who experience a sensitivity reaction the first time they take penicillin may have been sensitized by exposure to the Penicillium molds in the environment, including the Penicillium molds used to make brie, blue, camembert, roquefort, Stilton, and other “blue” cheeses.
Food/Drug Interactions Tetracycline. The calcium ions in milk products, including cheese, bind tetracyclines into insoluble compounds. If you take tetracyclines with cheese, your body may not be able to absorb and use the drug efficiently. Monoamine oxidase (MAO) inhibitors. Monoamine oxidase inhibitors are drugs used to treat depression. They inactivate naturally occurring enzymes in your body that metabolize tyra- mine, a substance found in many fermented or aged foods. Tyramine constricts blood ves- sels and increases blood pressure. If you eat a food such as aged or fermented cheese which is high in tyramine while you are taking an M AO inhibitor, your body may not be able to eliminate the tyramine. The result may be a hypertensive crisis.
Tyramine Content of Cheeses High Boursault, Camembert, Cheddar, Emmenthaler, Stilton Medium to high Blue, brick, Brie, Gruyère, mozzarella, Parmesan, Romano, Roquefort Low Processed American cheese Very little or none Cottage and cream cheese Sources: The Medical Letter Handbook of Adverse Drug Interactions (1985); Handbook of Clinical Dietetics ( The A merican Dietet ic Associat ion, 1981). False-positive test for pheochromocytoma. Pheochromocytomas (tumors of the adrenal glands) secrete adrenalin that is converted by the body to vanillyl-mandelic acid ( VM A) and excreted in the urine. Tests for this tumor measure the level of VM A in the urine. Since cheese contains VM A, taking the test after eating cheese may result in a false-positive result. Ordinarily, cheese is prohibited for at least 72 hours before this diagnostic test.... cheese
Habitat: Deccan Peninsula; common in the forest areas of Western Ghats.
Unani: Desi Ushbaa.Siddha/Tamil: Mahali kizhangu.Action: Root—appetizer, blood purifier, bacteriostatic. Used as a substitute for Shveta Saarivaa (Hemidesmus indicus). Sold as Saarivaa in Kerala, Tamil Nadu and Karnataka. The root powder is given to diabetics.
The root contains quercetin, kaempferol, coumarin and rutin. It has a sweet sarsaparilla-like taste; contains 92% fleshy matter and 8% woody core.The root can be stored for longer periods and remains unaffected by microorganisms and insects, apparently due to the presence of the volatile principle which possesses bacteriostat- ic and toxic properties.The root, on steam distillation, gave 4-O-methyl-resorcylaldehyde in a concentration of 0.8%. (The growth of E. coli was arrested by the aldehyde in 0.041% concentration; fish died within 4 min in 0.02% solution.) The sterols consists mainly of stagma and brassica sterols. Alpha-amyrin and lupeol, both free and as esters are also present in the root.The plant contains lupeol, beta- amyrin 2-hydroxy, 4-methoxy benzaldehyde, and ferulic acid.... decalepis hamiltoniiHabitat: Throughout India, ascending up to 2,100 m in the hills. (Native to tropical Africa and Madagascar.)
Folk: Amadok (Garhwal).Action: Disinfectant.
The plant is one of the major ingredients of an ointment used in the treatment of skin tumours in Chinese medicine. In Ivory Coast, Burkina Faso, Gabon and Tanganyika, different parts of the plant are used for the treatment of intercostal pain, rheumatic pain and fever. The leaf and root decoctions are used to treat pneumonia.The plant from Nigeria was found rich in phenolic ethers (45%), followed by monoterpenes (22%) and sesquiterpenes (12%). The major component of the oil was dimethyl thy- moquinone (44%). It showed activity against Gram-positive microorganisms. Dried powder of the plant contained artemisetin (artemetin).... laggera alataStructure Each tooth is composed of enamel, dentine, cement, pulp and periodontal membrane. ENAMEL is the almost translucent material which covers the crown of a tooth. It is the most highly calci?ed material in the body, 96–97 per cent being composed of calci?ed salts. It is arranged from millions of long, six-sided prisms set on end on the dentine (see below), and is thickest over the biting surface of the tooth. With increasing age or the ingestion of abrasive foods the teeth may be worn away on the surface, so that the dentine becomes visible. The outer sides of some teeth may be worn away by bad tooth-brushing technique. DENTINE is a dense yellowish-white material from which the bulk and the basic shape of a tooth are formed. It is like ivory and is harder than bone but softer than enamel. The crown of the tooth is covered by the hard protective enamel and the root is covered by a bone-like substance called cement. Decay can erode dentine faster than enamel (see TEETH, DISORDERS OF – Caries of the teeth). CEMENT or cementum is a thin bone-like material which covers the roots of teeth and helps hold them in the bone. Fibres of the periodontal membrane (see below) are embedded in the cement and the bone. When the gums recede, part of the cement may be exposed and the cells die. Once this has happened, the periodontal membrane can no longer be attached to the tooth and, if su?cient cement is destroyed, the tooth-support will be so weakened that the tooth will become loose. PULP This is the inner core of the tooth and is
composed of a highly vascular, delicate ?brous tissue with many ?ne nerve-?bres. The pulp is very sensitive to temperature variation and to touch. If the pulp becomes exposed it will become infected and usually cannot overcome this. Root-canal treatment or extraction of the tooth may be necessary. PERIODONTAL MEMBRANE This is a layer of ?brous tissue arranged in groups of ?bres which surround and support the root of a tooth in a bone socket. The ?bres are interspersed with blood vessels and nerves. Loss of the membrane leads to loss of the tooth. The membrane can release and re-attach the ?bres to allow the tooth to move when it erupts, or (to correct dental deformities) is being moved by orthodontic springs.
Arrangement and form Teeth are present in most mammals and nearly all have two sets: a temporary or milk set, followed by a permanent or adult set. In some animals, like the toothed whale, all the teeth are similar; but in humans there are four di?erent shapes: incisors, canines (eye-teeth), premolars (bicuspids), and molars. The incisors are chisel-shaped and the canine is pointed. Premolars have two cusps on the crown (one medial to the other) and molars have at least four cusps. They are arranged together in an arch in each jaw and the
cusps of opposing teeth interdigitate. Some herbivores have no upper anterior teeth but use a pad of gum instead. As each arch is symmetrical, the teeth in an upper and lower quadrant can be used to identify the animal. In humans, the quadrants are the same: in other words, in the child there are two incisors, one canine and two molars (total teeth 20); in the adult there are two incisors, one canine, two premolars and three molars (total 32). This mixture of tooth-form suggests that humans are omnivorous. Anatomically the crown of the tooth has mesial and distal surfaces which touch the tooth next to it. The mesial surface is the one nearer to the centre line and the distal is the further away. The biting surface is called the incisal edge for the anterior teeth and the occlusal surface for the posteriors.
Development The ?rst stage in the formation of the teeth is the appearance of a down-growth of EPITHELIUM into the underlying mesoderm. This is the dental lamina, and from it ten smaller swellings in each jaw appear. These become bell-shaped and enclose a part of the mesoderm, the cells of which become specialised and are called the dental papillae. The epithelial cells produce enamel and the dental papilla forms the dentine, cement and pulp. At a ?xed time the teeth start to erupt and a root is formed. Before the deciduous teeth erupt, the permanent teeth form, medial to them. In due course the deciduous roots resorb and the permanent teeth are then able to push the crowns out and erupt themselves. If this process is disturbed, the permanent teeth may be displaced and appear in an abnormal position or be impacted.
Eruption of teeth is in a de?nite order and at a ?xed time, although there may be a few months’ leeway in either direction which is of no signi?cance. Excessive delay is found in some congenital disorders such as CRETINISM. It may also be associated with local abnormalities of the jaws such as cysts, malformed teeth and supernumerary teeth.
The usual order of eruption of deciduous teeth is:
Middle incisors 6–8 months Lateral incisors 8–10 months First molars 12–16 months Canines (eye-teeth) 16–20 months Second molars 20–30 months
The usual order of eruption of permanent teeth is:
First molars 6–7 years Middle incisors 6–8 years Lateral incisors 7–9 years Canines 9–12 years First and second premolars 10–12 years Second molars 11–13 years Third molars (wisdom teeth) 17–21 years
The permanent teeth of the upper (top) and lower (bottom) jaws.
Teeth, Disorders of
Teething, or the process of eruption of the teeth in infants, may be accompanied by irritability, salivation and loss of sleep. The child will tend to rub or touch the painful area. Relief may be obtained in the child by allowing it to chew on a hard object such as a toy or rusk. Mild ANALGESICS may be given if the child is restless and wakens in the night. A serious pitfall is to assume that an infant’s symptoms of ill-health are due to teething, as the cause may be more serious. Fever and ?ts (see SEIZURE) are not due to teething.
Toothache is the pain felt when there is in?ammation of the pulp or periodontal membrane of a tooth (see TEETH – Structure). It can vary in intensity and may be recurring. The commonest cause is caries (see below) when the cavity is close to the pulp. Once the pulp has become infected, this is likely to spread from the apex of the tooth into the bone to form an abscess (gumboil – see below). A lesser but more long-lasting pain is felt when the dentine is unprotected. This can occur when the enamel is lost due to decay or trauma or because the gums have receded. This pain is often associated with temperature-change or sweet foods. Expert dental advice should be sought early, before the decay is extensive. If a large cavity is accessible, temporary relief may be obtained by inserting a small piece of cotton wool soaked, for example, in oil of cloves.
Alveolar abscess, dental abscess or gumboil This is an ABSCESS caused by an infected tooth. It may be present as a large swelling or cause trismus (inability to open the mouth). Treatment is drainage of the PUS, extraction of the tooth and/or ANTIBIOTICS.
Caries of the teeth or dental decay is very common in the more a?uent countries and is most common in children and young adults. Increasing awareness of the causes has resulted in a considerable improvement in dental health, particularly in recent years; this has coincided with a rise in general health. Now more than half of ?ve-year-old children are caries-free and of the others, 10 per cent have half of the remaining carious cavities. Since the start of the National Health Service, the emphasis has been on preventive dentistry, and now edentulous patients are mainly found among the elderly who had their teeth removed before 1948.
The cause of caries is probably acid produced by oral bacteria from dietary carbohydrates, particularly re?ned sugar, and this dissolves part of the enamel; the dentine is eroded more quickly as it is softer (see TEETH – Structure). The exposed smooth surfaces are usually protected as they are easily cleaned during normal eating and by brushing. Irregular and overcrowded teeth are more at risk from decay as they are di?cult to clean. Primitive people who chew coarse foods rarely get caries. Fluoride in the drinking water at about one part per million is associated with a reduction in the caries rate.
Prolonged severe disease in infancy is associated with poor calci?cation of the teeth, making them more vulnerable to decay. As the teeth are formed and partly calci?ed by the time of birth, the diet and health of the mother are also important to the teeth of the child. Pregnant mothers and children should have a good balanced diet with su?cient calcium and vitamin
D. A ?brous diet will also aid cleansing of the teeth and stimulate the circulation in the teeth and jaws. The caries rate can be reduced by regular brushing with a ?uoride toothpaste two or three times per day and certainly before going to sleep. The provision of sweet or sugary juices in an infant’s bottle should be avoided.
Irregularity of the permanent teeth may be due to an abnormality in the growth of the jaws or to the early or late loss of the deciduous set (see TEETH – Development). Most frequently it is due to an imbalance in the size of the teeth and the length of the jaws. Some improvement may take place with age, but many will require the help of an orthodontist (specialist dentist) who can correct many malocclusions by removing a few teeth to allow the others to be moved into a good position by means of springs and elastics on various appliances which are worn in the mouth.
Loosening of the teeth may be due to an accident or in?ammation of the GUM. Teeth loosened by trauma may be replaced and splinted in the socket, even if knocked right out. If the loosening is due to periodontal disease, the prognosis is less favourable.
Discoloration of the teeth may be intrinsic or extrinsic: in other words, the stain may be in the calci?ed structure or stuck on to it. Intrinsic staining may be due to JAUNDICE or the antibiotic tetracycline. Extrinsic stain may be due to tea, co?ee, tobacco, pan (a mixture of chuna and betel nuts wrapped in a leaf), iron-containing medicines or excess ?uoride.
Gingivitis or in?ammation of the gum may occur as an acute or chronic condition. In the acute form it is often part of a general infection of the mouth, and principally occurs in children or young adults – resolving after 10–14 days. The chronic form occurs later in life and tends to be progressive. Various microorganisms may be found on the lesions, including anaerobes. Antiseptic mouthwashes may help, and once the painful stage is past, the gums should be thoroughly cleaned and any calculus removed. In severe conditions an antibiotic may be required.
Periodontal disease is the spread of gingivitis (see above) to involve the periodontal membrane of the tooth; in its ?orid form it used to be called pyorrhoea. In this, the membrane becomes damaged by the in?ammatory process and a space or pocket is formed into which a probe can be easily passed. As the pocket becomes more extensive, the tooth loosens. The loss of the periodontal membrane also leads to the loss of supporting bone. Chronic in?ammation soon occurs and is di?cult to eradicate. Pain is not a feature of the disease but there is often an unpleasant odour (halitosis). The gums bleed easily and there may be DYSPEPSIA. Treatment is largely aimed at stabilising the condition rather than curing it.
Dental abscess is an infection that arises in or around a tooth and spreads to involve the bone. It may occur many years after a blow has killed the pulp of the tooth, or more quickly after caries has reached the pulp. At ?rst the pain may be mild and intermittent but eventually it will become severe and a swelling will develop in the gum over the apex of the tooth. A radiograph of the tooth will show a round clear area at the apex of the tooth. Treatment may be by painting the gum with a mild counter-irritant such as a tincture of aconite and iodine in the early stages, but later root-canal therapy or apicectomy may be required. If a swelling is present, it may need to be drained or the o?ending teeth extracted and antibiotics given.
Injuries to teeth are common. The more minor injuries include crazing and the loss of small chips of enamel, and the major ones include a broken root and avulsion of the entire tooth. A specialist dental opinion should be sought as soon as possible. A tooth that has been knocked out can be re-implanted if it is clean and replaced within a few hours. It will then require splinting in place for 4–6 weeks.
Prevention of dental disease As with other disorders, prevention is better than cure. Children should be taught at an early age to keep their teeth and gums clean and to avoid re?ned sugars between meals. It is better to ?nish a meal with a drink of water rather than a sweetened drink. Fluoride in some of its forms is useful in the reduction of dental caries; in some parts of the UK natural water contains ?uoride, and in some areas where ?uoride content is low, arti?cial ?uoridation of the water supply is carried out. Overcrowding of the teeth, obvious maldevelopment of the jaw and persistent thumbsucking into the teens are all indications for seeking the advice of an orthodontist. Generally, adults have less trouble with decay but more with periodontal disease and, as its onset is insidious, regular dental inspections are desirable.... teeth
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
If you’re looking for a special herbal tea, you can try pipsissewa tea. It has a pleasant taste, slightly bitter, like most herbal teas, but also a bit sweet. Also, it comes with many health benefits. Read to find out more!
About Pipsissewa Tea
Pipsissewa tea is made from the pipsissewa plant, also known as Umbellate Wintergreen or Prince’s pine. It is a small, evergreen perennial plant, usually found in the dry woodlands or sandy soils of Southern Canada and northern United States.
The plant can grow up to 30cm tall. It usually has 4 evergreen, shiny leaves with a toothed margin; they’re arranged one opposite the other on the stem. It has 4-8 flowers, either pink or white, which bloom during summer.
The pipsissewa plant is used to make root beer. It can also be used to flavor candies and soft drinks.
How to prepare Pipsissewa Tea
You only need a few minutes to prepare a cup of pipsissewa tea. Put a tablespoon of herbs in the cup, then pour freshly boiled water over it. Let it steep for 2-4 minutes; then, strain the drink. Sweeten it with milk or honey, if you wish.
Pipsissewa Tea Benefits
Pipsisewa, as a plant, contains many important constituents which are also transferred to the pipsissewa tea. Some of them are hydroquinones (for example, arbutin), flavonoids, triterpenes, methyl salicylate, phenols, essential oils, and tannins. They have many health benefits.
Pipsissewa teais often recommended in the treatment for infections of the urinary tract, such as cystitis, painful urination, bladder and kidney stones, kidney inflammation, prostatitis, gonorrhea, and urethritis. It can also be used to treat arthritis, gout and rheumatism.
Drinking pipsissewa tea will help your body expel various infectious microorganisms. It can increase sweating in order to treat fever diseases. It is also often included in the treatment for ailments of the respiratory tract, such as colds, whooping cough, and bronchitis.
Pipsissewa tea can be used topically, as well. It can be used with blisters, tumors, and swellings. Also, you can use it as an eye wash if you’ve got sore eyes.
Pipsissewa Tea Side Effects
It is not well-known if pipsissewa tea can affect women during pregnancy or breast feeding. However, it’s considered safe not to drink it, just in case it might affect the baby.
It is best not to drink pipsissewa tea if you’re taking medication for the intestine, or if you’ve got iron deficiency.
Drinking a large amount of pipsissewa tea can also lead to a few side effects. The symptoms you might get are: diarrhea, nausea, vomiting, headaches, and loss of appetite.
You’ll definitely enjoy drinking pipsissewa tea, both for its pleasant taste and because of the health benefits it has.
... have a cup of pipsissewa teaVisceral rickettsia is a disease transmitted by mites from an infected house mouse, which occurs in the USA, South Africa, Korea and the former Soviet Union. The causal organism is Rickettsia akari. The incubation period is 7–14 days and the characteristic features are fever, headache, and a non-irritating rash on the face, trunk and extremities. The disease is non-fatal and responds rapidly to TETRACYCLINES.... rickettsia
Hydrocoele is a collection of ?uid distending one or both sides of the scrotum with ?uid. Treatment is by withdrawal of the ?uid using a sterile syringe and aspiration needle.
Hypogonadism Reduced activity of the testes or ovaries (male and female gonads). The result is impaired development of the secondary sexual characteristics (growth of the genitals, breast and adult hair distribution). The cause may be hereditary or the result of a disorder of the PITUITARY GLAND which produces GONADOTROPHINS that stimulate development of the testes and ovaries.
Varicocoele is distension of the veins of the spermatic cord, especially on the left side, the causes being similar to varicose veins elsewhere (see VEINS, DISEASES OF). The chief symptom is a painful dragging sensation in the testicle, especially after exertion. Wearing a support provides relief; rarely, an operation may be advisable. Low sperm-count may accompany a varicocele, in which case surgical removal may be advisable.
Orchitis or acute in?ammation may arise from CYSTITIS, stone in the bladder, and in?ammation in the urinary organs, especially GONORRHOEA. It may also follow MUMPS. Intense pain, swelling and redness occur; treatment consists of rest, support of the scrotum, analgesics as appropriate, and the administration of antibiotics if a de?nitive microorganism can be identi?ed. In some patients the condition may develop and form an ABSCESS.
Torsion or twisting of the spermatic cord is relatively common in adolescents. About half the cases occur in the early hours of the morning during sleep. Typically felt as pain of varying severity in the lower abdomen or scrotum, the testis becomes hard and swollen. Treatment consists of immediate undoing of the torsion by manipulation. If done within a few hours, no harm should ensue; however, this should be followed within six hours by surgical operation to ensure that the torsion has been relieved and to ?x the testes. Late surgical attention may result in ATROPHY of the testis.
Tuberculosis may occur in the testicle, especially when the bladder is already affected. Causing little pain, the infection is often far advanced before attracting attention. The condition generally responds well to treatment with a combination of antituberculous drugs (see also main entry for TUBERCULOSIS).
Tumours of the testes occur in around 600 males annually in the United Kingdom, and are the second most common form of malignant growth in young males. There are two types: SEMINOMA and TERATOMA. When adequately treated the survival rate for the former is 95 per cent, while that for the latter is 50 per cent.
Injuries A severe blow may lead to SHOCK and symptoms of collapse, usually relieved by rest in bed; however, a HAEMATOMA may develop.... testicle, diseases of
(See also disinfectants; aseptic technique.)... antiseptics
Antiserum is usually used, along with immunization, as an emergency treatment when someone has been exposed to a dangerous infection such as rabies and has not previously been immunized.... antiserum
Habitat: Native to China; planted all over India in gardens.
English: Oriental Arbor-Vitae.Folk: Morepankhi.Action: Leaves—diuretic, insectici- dal antipyretic.
The leaves contain rhodoxanthin, amentoflavone, hinokiflavone, querce- tin, myricetin, carotene (20.8 mg/100 g dry basis), xanthophyll and ascorbic acid (68 mg/100 g). Essential oil, obtained from twigs (0.32) and berries (0.25%), contains alpha-thujene, (+)- sabinene, (+)-camphene, cedrol, ce- drenol and alpha-and beta-pinenes as major constituents.American Arbor-Vitae and White Cedar has been equated with T. occidentals and is used as Thuja.It was introduced into India from North America, and grows as a Christmas tree in the plains of India.Leaves—aninfusionisusedasa uterine stimulant, emmenagogue and diuretic. Boiled in lard, are applied externally for rheumatism. Bark—astringent, emmenagogue, diuretic. Oil— poisonous, disinfectant, insecticidal. Seed and fruit— antibacterial; inhibited the growth of Gram-positive microorganisms.The leaves yields a volatile oil, containing thujone as major component, with iso-thujone, borneol, bornyl acetate, l-fenchone, limonene, sabinene, camphor, l-alpha-thujene; flavonoids, mucilage, tannins.The heartwood yields a non-toxic antibiotic substance. It gave sesquiter- pene alcohols—occidentalol and oc- cidol; also alpha-beta-and gamma- eudesmol.Thuja is used in homoeopathy for tissue degeneration and tumours, warts and fungoid growths, both internally and externally.... thuja orientalisThe response consists of the production of cells called lymphocytes, substances called antibodies, or immunoglobulins, and other substances and cells that act to destroy the antigenic material.
(See also immune system.)... immune response
Macrophages are large phagocytes, which can engulf and destroy microorganisms and other foreign particles.
They are found in most body tissues.... macrophage
Healthy people are inoculated with vaccine as a protection against a particular disease; this produces ANTIBODIES which will confer immunity against a subsequent attack of the disease. (See IMMUNISATION for programme of immunisation during childhood.)
Vaccines may be divided into two classes: stock vaccines, prepared from micro-organisms known to cause a particular disease and kept in readiness for use against that disease; and autogenous vaccines, prepared from microorganisms which are already in the patient’s body and to which the disease is due. Vaccines intended to protect against the onset of disease are of the former variety.
Autogenous vaccines are prepared by cultivating bacteria found in SPUTUM, URINE and FAECES, and in areas of in?ammation such as BOILS (FURUNCULOSIS). This type of vaccine was introduced by Wright about 1903.
Anthrax vaccine was introduced in 1882 for the protection of sheep and cattle against this disease. A safe and e?ective vaccine for use in human beings has now been evolved. (See ANTHRAX.)
BCG vaccine is used to provide protection against TUBERCULOSIS. (See also separate entry on BCG VACCINE.)
Cholera vaccine was introduced in India about 1894. Two injections are given at an interval of at least a week; this gives a varying degree of immunity for six months. (See CHOLERA.)
Diphtheria vaccine is available in several forms. It is usually given along with tetanus and pertussis vaccine (see below) in what is known as TRIPLE VACCINE. This is given in three doses: the ?rst at the age of two months; the second at three months; and the third at four months, with a booster dose at the age of ?ve years. (See DIPHTHERIA.)
Hay fever vaccine is a vaccine prepared from the pollen of various grasses. It is used in gradually increasing doses for prevention of HAY FEVER in those susceptible to this condition.
In?uenza vaccine A vaccine is now available for protection against INFLUENZA due to the in?uenza viruses A and B. Its use in Britain is customarily based on advice from the health departments according to the type of in?uenza expected in a particular year.
Measles, mumps and rubella (MMR) vaccines are given in combination early in the second year of life. A booster dose may prove necessary, as there is some interference between this vaccine and the most recent form of pertussis vaccine (see below) o?ered to children. Uptake has declined a little because of media reports suggesting a link with AUTISM – for which no reliable medical evidence (and much to the contrary) has been found by investigating epidemiologists. (See also separate entry for each disease, and for MMR VACCINE.)
Pertussis (whooping-cough) vaccine is prepared from Bordetella pertussis, and is usually given along with diphtheria and tetanus in what is known as triple vaccine. (See also WHOOPING-COUGH.)
Plague vaccine was introduced by Ha?kine, and appears to give useful protection, but the duration of protection is relatively short: from two to 20 months. Two injections are given at an interval of four weeks. A reinforcing dose should be given annually to anyone exposed to PLAGUE.
Poliomyelitis vaccine gives a high degree of protection against the disease. This is given in the form of attenuated Sabin vaccine which is taken by mouth – a few drops on a lump of sugar. Reinforcing doses of polio vaccine are recommended on school entry, on leaving school, and on travel abroad to countries where POLIOMYELITIS is ENDEMIC.
Rabies vaccine was introduced by Pasteur in 1885 for administration, during the long incubation period, to people bitten by a mad dog, in order to prevent the disease from developing. (See RABIES.)
Rubella vaccine, usually given with mumps and measles vaccine in one dose – called MMR VACCINE, see also above – now provides protection against RUBELLA (German measles). It also provides immunity for adolescent girls who have not had the disease in childhood and so ensures that they will not acquire the disease during any subsequent pregnancy – thus reducing the number of congenitally abnormal children whose abnormality is the result of their being infected with rubella via their mothers before they were born.
Smallpox vaccine was the ?rst introduced. As a result of the World Health Organisation’s successful smallpox eradication campaign – it declared the disease eradicated in 1980 – there is now no medical justi?cation for smallpox vaccination. Recently, however, there has been increased interest in the subject because of the potential threat from bioterrorism. (See also VACCINATION.)
Tetanus vaccine is given in two forms: (1) In the so-called triple vaccine, combined with diphtheria and pertussis (whooping-cough) vaccine for the routine immunisation of children (see above). (2) By itself to adults who have not been immunised in childhood and who are particularly exposed to the risk of TETANUS, such as soldiers and agricultural workers.
Typhoid vaccine was introduced by Wright and Semple for the protection of troops in the South African War and in India. TAB vaccine, containing Salmonella typhi (the causative organism of typhoid fever – see ENTERIC FEVER) and Salmonella paratyphi A and B (the organisms of paratyphoid fever – see ENTERIC FEVER) has now been replaced by typhoid monovalent vaccine, containing only S. typhi. The change has been made because the monovalent vaccine is less likely to produce painful arms and general malaise, and there is no evidence that the TAB vaccine gave any protection against paratyphoid fever. Two doses are given at an interval of 4–6 weeks, and give protection for 1–3 years.... vaccine
Phagocytes are found in the blood, spleen, lymph nodes, and alveoli (small air sacs) within the lungs.... phagocyte
It is the chief cause of tooth decay (see caries, dental) and gingivitis, and forms the basis of a hard deposit (see calculus, dental).
Some of the microorganisms in plaque, particularly STREPTOCOCCUS MUTANS, break down sugar in the remains of carbohydrate food that sticks to the mucus, creating an acid that can erode tooth enamel.... plaque, dental
Allergic reactions occur only on 2nd or subsequent exposure to the allergen, once 1st contact has sensitized the body. The function of the immune system is to recognize antigens (foreign proteins) on the surfaces of microorganisms and to form antibodies (also called immunoglobulins) and sensitized lymphocytes (white blood cells). When the immune system next encounters the same antigens, the antibodies and sensitized lymphocytes interact with them, leading to destruction of the microorganisms.
A similar immune response occurs in allergies, except that the immune system forms antibodies or sensitized lymphocytes against harmless substances because these allergens are misidentified as potentially harmful antigens.
The inappropriate or exaggerated reactions seen in allergies are termed
Allergen hypersensitivity reactions and can have any of four different mechanisms (termed Types I to hypersensitivity reactions).
Most well known allergies are caused by Type I (also known as anaphylactic or immediate) hypersensitivity in which allergens cause immediate symptoms by provoking the immune system to produce specific antibodies, belonging to a type called immunoglobulin E
(IgE), which coat cells (called mast cells or basophils). When the allergen is encountered for the second time, it binds to the IgE antibodies and causes the granules in mast cells to release various chemicals, which are responsible for the symptoms of the allergy.
Among the chemicals released is histamine, which causes widened blood vessels, leakage of fluid into tissues, and muscle spasm. Symptoms can include itching, swelling, sneezing, and wheezing. Particular conditions associated with Type I reactions include asthma, hay fever, urticaria (nettle rash), angioedema, anaphylactic shock (a severe, generalized allergic reaction), possibly atopic eczema, and many food allergies.
Types to hypersensitivity reactions are less often implicated in allergies. However, contact dermatitis, in which the skin reacts to substances such as nickel, is due to a Type hypersensitivity reaction.
It is not known why certain individuals and not others get allergies, but about 1 in 8 people seem to have an inherited predisposition to them (see atopy).
Whenever possible, the most effective treatment for allergy of any kind is avoidance of the relevant allergen.
Drug treatment for allergic reactions includes the use of antihistamine drugs, which relieve the symptoms. Some antihistamine drugs have a sedative effect, which is useful in treating itching at night due to eczema. Many antihistamines do not cause drowsiness, making them more suitable for daytime use.
Other drugs, such as sodium cromoglicate and corticosteroid drugs, can be used regularly to prevent symptoms from developing.
Hyposensitization can be valuable for a minority of people who suffer allergic reactions to specific allergens such as bee stings. Treatment involves gradually increasing doses of the allergen, but it must be carried out under close supervision because a severe allergic reaction can result.... allergy
When haemolysis is due to a defect inside the red cells, the underlying problem is abnormal rigidity of the cell membrane. This causes the cells to become trapped, at an early stage of their life-span, in the small blood vessels of the spleen, where they are destroyed by macrophages (cells that ingest foreign particles). Abnormal rigidity may result from an inherited defect of the cell membrane (as in hereditary spherocytosis), a defect of the haemoglobin in the cell (as in sickle-cell anaemia), or a defect of one of the cell’s enzymes. An inherited deficiency of the glucose-6phosphate dehydrogenase enzyme (see G6PD deficiency) may result in episodes of haemolytic anaemia since the red cells are prone to damage by infectious illness or certain drugs or foods.
Haemolytic anaemias due to defects outside the red cells fall into 3 main groups. First are disorders in which red cells are destroyed by buffeting (by artificial surfaces such as replacement heart valves, abnormal blood-vessel linings, or a blood clot in a vessel, for example). In the 2nd group, the red cells are destroyed by the immune system. Immune haemolytic anaemias may occur if foreign blood cells enter the bloodstream, as occurs in an incompatible blood transfusion, or they may be due to an autoimmune disorder. In haemolytic disease of the newborn, the baby’s red cells are destroyed by the mother’s antibodies crossing the placenta. Thirdly, the red cells may be destroyed by microorganisms; the most common cause is malaria. People with haemolytic anaemia may have symptoms common to all types of anaemia, such as fatigue and breathlessness, or symptoms specifically due to haemolysis, such as jaundice.
Diagnosis is made by examination of the blood (see blood film). Some inherited anaemias can be controlled by removing the spleen (see splenectomy). Others, such as G6PD deficiency, can be prevented by avoiding the drugs or foods that precipitate haemolysis. Anaemias due to immune processes can often be controlled by immunosuppressant drugs. Transfusions of red cells are sometimes needed for emergency treatment of life-threatening anaemia.... anaemia, haemolytic
In medicine, it has several different meanings.
A resistance to the flow of blood is exerted by the blood vessel walls.
Increased resistance leads to raised blood pressure.
In psychoanalysis, resistance refers to the blocking off from consciousness of repressed memories or emotions.
Resistance may also refer to an ability to withstand attack from poisons, irritants, or microorganisms.
A person’s resistance to infection is called immunity.
The term drug resistance refers to the ability of some microorganisms to withstand attack from previously effective drug treatments.... resistance
In cutaneous anthrax, a raised, itchy, area develops at the site of entry of the spores, progressing to a large blister and finally a black scab, with swelling of the surrounding tissues.
This is treatable with penicillin in its early stages.
Without treatment, the infection may spread to lymph nodes and the bloodstream, and may be fatal.
Pulmonary anthrax causes severe breathing difficulty and is fatal in most cases.... anthrax
Inappropriate or excessive formation of antibodies may lead to illness, as in an allergy.
Antibodies against antigens in organ transplants may result in rejection of the transplanted organ.
In some disorders, antibodies are formed against the body’s own tissues, resulting in an autoimmune disorder.... antibody
These people include health workers, contacts of people who have tuberculosis, and immigrants (including children) from countries with a high rate of tuberculosis.
Infants born to immigrants in this category are immunized, without having a tuberculin test, within a few days of birth.
The vaccine is also recommended for children aged 10–14 years for whom the test is negative.... bcg vaccination
in septicaemia. Microbiology also looks for antibodies in the blood, which may confirm immunity to an infection. blood transfusion The infusion of large volumes of blood or blood products directly into the bloodstream to remedy severe blood loss or to correct chronic anaemia. In an exchange transfusion, nearly all of the recipient’s blood is replaced by donor blood. Before a transfusion, a sample of the recipient’s blood is taken to identify the blood groups, and it is matched with suitable donor blood. The donor blood is transfused into an arm vein through a plastic cannula. Usually, each unit (about 500 ml) of blood is given over 1–4 hours; in an emergency, 500 ml may be given in a couple of minutes. The blood pressure, temperature, and pulse are monitored during the procedure.
If mismatched blood is accidentally introduced into the circulation, antibodies in the recipient’s blood may cause donor cells to burst, leading to shock or kidney failure. Less severe reactions can produce fever, chills, or a rash. Reactions can also occur as a result of an allergy to transfused blood components. All
blood used for transfusion is carefully screened for a number of infectious agents, including HIV (the AIDS virus) and hepatitis B and hepatitis C.
In elderly or severely anaemic patients, transfusion can overload the circulation, leading to heart failure.
In patients with chronic anaemia who need regular transfusion over many years, excess iron may accumulate (haemosiderosis) and damage organs such as the heart, liver, and pancreas.
Treatment with desferrioxamine to remove excess iron may be needed.... blood tests
It contains salts, glucose, and proteins, including antibodies.
Serum from the blood of a person who has been infected with a microorganism usually contains antibodies that can protect other people from that organism if injected into them.
Such a preparation is called an antiserum; its use forms the basis of passive immunization.... serum
The first, CHLAMYDIA TRACHOMATIS, has a number of strains. In men, it is a major cause of nongonococcal urethritis, which may cause a discharge from the penis. In women, the infection is usually symptomless, but it can lead to salpingitis. A baby born to a woman with chlamydial infection may acquire an acute eye condition called neonatal ophthalmia. In parts of Africa and Asia, certain strains of CHLAMYDIA TRACHOMATIS cause trachoma, a serious eye disease.
A second species of chlamydiae, CHLAMYDIA PSITTACI, mainly affects birds but can occasionally spread to people who have contact with pigeons, parrots, parakeets, or poultry, causing a type of pneumonia called psittacosis.
Treatment for chlamydial infections is with antibiotic drugs.... chlamydial infections
Investigations into colitis may include examining a faecal sample, sigmoidoscopy or colonoscopy, biopsy of inflamed areas or ulcers, and a barium enema (see barium X-ray examinations).
If the cause is an infection, antibiotics may be needed.
Crohn’s disease and ulcerative colitis are treated with corticosteroid and immunosuppressant drugs, and a special diet.... colitis
Seborrhoeic dermatitis is a red, scaly, itchy rash that develops on the face, scalp, chest, and back. The rash often develops during times of stress and is probably caused by an excess growth of yeast on the skin. Corticosteroid drugs and/or drugs that kill microorganisms may help. Contact dermatitis results from a reaction to some substance that comes
in contact with the skin. Common causes are detergents, nickel, certain plants, and cosmetics. It may be treated with topical corticosteroids. A patch test (see skin tests) may be done to identify the cause. Photodermatitis occurs in people whose skin is abnormally sensitive to light. A cluster of spots or blisters occurs on any part of the body exposed to the sun (see photosensitivity). dermatitis artefacta Any self-induced skin condition. It may range from a mild scratch to extensive mutilation. dermatitis herpetiformis A chronic skin disease in which clusters of tiny, red, intensely itchy blisters occur in a symmetrical pattern, most commonly on the back, elbows, knees, buttocks, and scalp. It usually develops in adult life and is believed to be related to coeliac disease. dermatology The branch of medicine concerned with the skin and its disorders. dermatome An area of skin supplied with nerves by a pair of spinal nerve roots from the cervical (C2–C8), thoraci.
(T1–T12), lumbar (L1–L5), and sacral (S1–S5) regions.
The entire body surface is an interlocking pattern of dermatomes, which is similar from one person to another.
Abnormal sensation in a dermatome signifies damage to a particular nerve root, commonly due to a disc prolapse.... dermatitis
Endocarditis may be either subacute or acute. In the subacute form, symptoms are general and nonspecific, although serious damage may be caused to a heart valve; the sufferer may complain of fatigue, feverishness, and vague aches and pains. On physical examination, the only evident abnormality may be a heart murmur. Acute endocarditis, which occurs less frequently, comes on suddenly, and causes severe chills, high fever, shortness of breath, and rapid or irregular heartbeat. The infection progresses quickly and may destroy the heart valves, leading to heart failure.
Endocarditis is diagnosed by physical examination and analysis of blood samples.
Tests on the heart may include ECG, echocardiography, and angiography.
Treatment is with high doses of antibiotic drugs, which are usually given intravenously.
Heart-valve surgery may be needed to replace a damaged valve.... endocarditis
Tonsillitis is treated with plenty of fluids and an analgesic drug such as paracetamol; in some cases antibiotic drugs may also be prescribed.... tonsillitis
Urethritis may be caused by various infectious organisms, including the bacterium that causes gonorrhoea. Nongonococcal urethritis may be caused by any of a large number of different types of microorganisms. Urethritis may also be caused by damage from an accident
or from a catheter or cystoscope.
Other possible causes include irritant chemicals, such as antiseptics and some spermicidal preparations.
Treatment of infection is with antibiotic drugs.... urethritis
Most fevers are caused by a bacterial infection such as tonsillitis or a viral infection such as influenza. In these cases, proteins called pyrogens are released when the white blood cells fight the microorganisms that are responsible for the infection. Pyrogens act on the temperature controlling centre in the brain, causing it to raise the body temperature in an attempt to destroy the invading microorganisms. Fever may also occur in conditions, such as dehydration, thyrotoxicosis, lymphoma, and myocardial infarction, where infection is not present.
Drugs such as aspirin or other nonsteroidal anti-inflammatory drugs, or paracetamol may be given to reduce fevers that are due to infections.
Otherwise, treatment is directed at the underlying cause (for example, giving antibiotic drugs for a bacterial infection).... fever
The term innate immunity is given to the protection that we are born with, such as the skin and the mucous membranes that line the mouth, nose, throat, intestines, and vagina. It also includes antibodies, or immunoglobulins (protective proteins), that have been passed to the child from the mother. If microorganisms penetrate these defences, they encounter “cell-devouring” white blood cells called phagocytes, and other types of white cells, such as natural cellkilling (cytotoxic) cells. Microorganisms may also meet naturally produced substances (such as interferon) or a group of blood proteins called the complement system, which act to destroy the invading microorganisms.The 2nd part of the immune system, adaptive immunity, comes into play when the body encounters organisms that overcome the innate defences. The adaptive immune system responds specifically to each type of invading organism, and retains a memory of the invader so that defences can be rallied instantly in the future.
The adaptive immune system first must recognize part of an invading organism or tumour cell as an antigen (a protein that is foreign to the body). One of 2 types of response – humoral or cellular – is then mounted against the antigen.
Humoral immunity is important in the defence against bacteria. After a complex recognition process, certain B-lymphocytes multiply and produce vast numbers of antibodies that bind to antigens. The organisms bearing the antigens are then engulfed by phagocytes. Binding of antibody and antigen may activate the complement system, which increases the efficiency of the phagocytes.
Cellular immunity is particularly important in the defence against viruses, some types of parasites that hide within cells, and, possibly, cancer cells. It involves 2 types of T-lymphocyte: helper cells, which play a role in the recognition of antigens and activate the killer cells (the 2nd type of T-lymphocyte), which destroy the cells that have been invaded.
Disorders of the immune system include immunodeficiency disorders and allergy, in which the immune system has an inappropriate response to usually innocuous antigens such as pollen.
In certain circumstances, such as after tissue transplants, immunosuppressant drugs are used to suppress the immune system and thus prevent rejection of the donor tissue as a foreign organism.... immune system
Immunoglobulin G (IgG) is the major class of immunoglobulin of the 5 in the blood (IgA, IgD, IgE, IgG, and IgM). Its molecule consists of 2 parts: 1 binds to an antigen; the other binds to other cells, which then engulf the microorganisms bearing the antigen.
Immunoglobulins can be extracted from the blood of people who have recovered from certain infectious diseases and used for passive immunization.... immunoglobulin
Many minor infections are dealt with by the immune system and need no specific treatment. Severe systemic infections may need treatment with drugs such as antibacterials or antivirals. A localized infection that has produced pus may be drained surgically.... infection
Infections acquired during birth are almost always the result of microorganisms in the mother’s vaginal secretions or uterine fluid. Premature rupture of the membranes is associated with increased risk of infection, particularly streptococcal. Conditions that can be acquired during delivery include herpes, chlamydial infections, and gonorrhoea.
Treatment of the baby depends on the type of infection. Some birth defects caused by infection (such as certain types of heart defect) can be treated; others (such as congenital deafness) are usually not treatable.... infection, congenital
In developed countries, infectious diseases are generally less of a threat than in the past because of better methods to control the spread of disease organisms (such as better sanitation and water purification); effective drugs; immunization; and better general health and nutrition.
For most infectious diseases, there is a time gap between the entry of the microorganisms into the body and the 1st appearance of symptoms. This incubation period, during which an infected person is likely to pass the microorganism to others, may be a few hours, a few days, or, in some cases, months.
Antibiotics and other antimicrobial drugs are the mainstay of treatment for bacterial infection. For viral infection, however, drug treatment is restricted to severe infections.... infectious disease
Inflammation is usually accompanied by a local increase in the number of white blood cells. These cells help to destroy any invading microorganisms and are involved in repairing the damaged tissue. Inappropriate inflammation (as in rheumatoid arthritis and some
Injured skin other autoimmune disorders) may be suppressed by corticosteroid drugs or by nonsteroidal anti-inflammatory drugs.... inflammation
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