Trans: From 1 Different Sources
prefix denoting through or across. Example: transurethral (through the urethra).
See TRANSFUSION – Transfusion of blood.... blood transfusion
A method of treating newborn infants with HAEMOLYTIC DISEASE. Blood is taken out of the baby through the umbilical vein and is replaced with the same quantity of blood from a donor that is compatible with the mother’s blood. The procedure is repeated several times to get rid of damaged cells while maintaining the infant’s blood volume and keeping its red cell count constant. (See also TRANSFUSION.)... exchange transfusion
Reconstructive surgery in which the TENDON from an unimportant muscle is removed and used to repair or replace a damaged tendon of a major muscle.... tendon transfer
The administration of any ?uid into a person’s vein using a drip. This apparatus facilitates a continuous injection in which the ?uid ?ows by force of gravity from a suspended bottle, via a tube that is ?xed to a hollow needle inserted into a vein (usually in the front of the elbow). Saline solution, PLASMA and whole BLOOD (see below) are the most commonly administered ?uids. Saline is used to restore ?uid to a seriously dehydrated individual (see DEHYDRATION) and may be used as a temporary measure in SHOCK due to blood loss while the appropriate type of blood is being obtained for transfusion. Saline may also be useful as a way of administering a regular supply of a drug over a period of time. Plasma is normally used as a temporary measure in the treatment of shock until appropriately matched blood is available or if for any reason, such as for a patient with severe burns, plasma is preferable to blood.
Transfusion of blood is a technique that has been used since the 17th century – although, until the 20th century, with a subsequent high mortality rate. It was only when incompatibility of BLOOD GROUPS was considered as a potential cause of this high mortality that routine blood-testing became standard practice. Since the National Blood Transfusion Service was started in the United Kingdom (in 1946), blood for transfusion has been collected from voluntary, unpaid donors: this is screened for infections such as SYPHILIS, HIV, HEPATITIS and nvCJD (see CREUTZFELDT-JAKOB DISEASE (CJD)), sorted by group, and stored in blood-banks throughout the country.
In the UK in 2004, the National Blood Authority – today’s transfusion service – announced that it would no longer accept donations from anyone who had received a blood transfusion since 1980 – because of the remote possibility that they might have been infected with the PRION which causes nvCJD.
A standard transfusion bottle has been developed, and whole blood may be stored at 2–6 °C for three weeks before use. Transfusions may then be given of whole blood, plasma, blood cells, or PLATELETS, as appropriate. Stored in the dried form at 4–21 °C, away from direct sunlight, human plasma is stable for ?ve years and is easily reconstituted by adding sterile distilled water.
The National Blood Authority prepares several components from each donated unit of blood: whole blood is rarely used in adults. This permits each product, whether plasma or various red-cell concentrates, to be stored under ideal conditions and used in appropriate clinical circumstances – say, to restore blood loss or to treat haemostatic disorders.
Transfusion of blood products can cause complications. Around 5 per cent of transfused patients suffer from a reaction; most are mild, but they can be severe and occasionally fatal. It can be di?cult to distinguish a transfusion reaction from symptoms of the condition being treated, but the safe course is to stop the transfusion and start appropriate investigation.
In the developed world, clinicians can expect to have access to high-quality blood products, with the responsibility of providing blood resting with a specially organised transfusion service. The cause of most fatal haemolytic transfusion reactions is a clerical error due to faulty labelling and/or failure to identify the recipient correctly. Hospitals should have a strict protocol to prevent such errors.
Arti?cial blood Transfusion with blood from donors is facing increasing problems. Demand is rising; suitable blood donors are becoming harder to attract; the processes of taking, storing and cross-matching donor blood are time-consuming and expensive; the shelf-life is six weeks; and the risk of adverse reactions or infection from transfused blood, although small, is always present. Arti?cial blood would largely overcome these drawbacks. Several companies in North America are now preparing this: one product uses puri?ed HAEMOGLOBIN from humans and another from cows. These provide oxygen-carrying capacity, are unlikely to be infectious and do not provoke immunological rejections. Yet another product, called Oxygene®, does not contain any animal or human blood products; it comprises salt water and a substance called per?ubron, the molecules of which store oxygen and absorb carbon dioxide more e?ectively than does haemoglobin. Within 24 hours of being transfused into a person’s bloodstream, per?ubron evaporates and is harmlessly breathed out by the recipient. Arti?cial blood is especially valuable in that it contains no unwanted proteins that can provoke adverse immunological reactions. Furthermore, it is disease-free, lasts for up to three years and is no more expensive than donor blood. It could well take the place of donor blood within a few years.
Autologous transfusion is the use of an individual’s own blood, provided in advance, for transfusion during or after a surgical operation. This is a valuable procedure for operations that may require large transfusions or where a person has a rare blood group. Its use has increased for several reasons:
fear of infection such as HIV and hepatitis.
shortages of donor blood and the rising cost of units of blood.
substantial reduction of risk of incompatible transfusions. In practice, blood transfusion in the UK is
remarkably safe, but there is always room for improvement. So, in the 1990s, a UK inquiry on the Serious Hazards of Transfusion (SHOT) was launched. It established (1998) that of 169 recently reported serious hazards following blood transfusion, 81 had involved a blood component being given to the wrong patient, while only eight were the result of viral or bacterial infections.
There are three ways to use a patient’s own blood in transfusion:
(1) predeposit autologous donation (PAD) – taking blood from a patient before operation and transfusing this blood back into the patient as required during and after operation.
(2) acute normovalaemic haemodilution (ANH) – diluting previously withdrawn blood and thus increasing the volume before transfusion.
(3) perioperative cell salvage (PCS) – the use of centrifugal cell separation on blood saved during an operation, particularly spinal surgery where blood loss may be considerable.
The government has urged NHS trusts to consider the introduction of PCS as a possible adjunct or alternative to banked-blood transfusion. In one centre (Nottingham), PCS has been used in the form of continuous autologous transfusion for several years with success.
Exchange transfusion is the method of treatment in severe cases of HAEMOLYTIC DISEASE OF THE NEWBORN. It consists of replacing the whole of the baby’s blood with Rh-negative blood of the correct blood group for the baby.... transfusion
The term used to describe an exchange of genetic material between CHROMOSOMES. It is an important factor in the etiology, or causation, of certain congenital abnormalities such as, for example, DOWN’S (DOWN) SYNDROME. It is one of the main abnormalities sought for in AMNIOSCOPY.... translocation
A procedure in which cells – for example, from the pancreas – are taken from an aborted FETUS and then transplanted into the malfunctioning organ (pancreas) of an individual with a disorder of that organ (in this case, diabetes). The cells from the fetus are intended to take over the function of the host’s diseased or damaged cells. Fetal brain cells have also been transplanted into brains of people suffering from PARKINSONISM. These treatments are at an experimental stage.... fetal transplant
A treatment for a stenosed (restricted) coronary artery (see ARTERIES). A balloon-tipped catheter (see CATHETERS) is passed through an incision in the skin of the chest into the artery of the HEART that has developed stenosis (narrowing). The balloon is aligned with the stenosed section and then in?ated to dilate the coronary artery and allow the blood to ?ow more freely.... percutaneous transluminal coronary angioplasty
An ENZYME, usually found in retroviruses (see RETROVIRUS), that catalyses the manufacture of DNA from RNA, enabling the viral RNA to amalgamate with the DNA of the infected host.... reverse transcriptase
In this team, each member becomes so familiar with the roles and responsibilities of the other members that tasks and functions become interchangeable to some extent. This type of team is difficult to operationalize.... transdisciplinary team
(GIFT) A technique for assisting conception (see infertility), which can only be used if a woman has normal fallopian tubes. In , eggs are removed from an ovary during laparoscopy and mixed with sperm in the laboratory before both are introduced into a fallopian tube. A fertilized egg may then become implanted in the uterus.... gamete intrafallopian transfer
See TENS.... transcutaneous electrical nerve stimulation
The unconscious displacement of emotions from people who were important during one’s childhood, such as parents, to other people during adulthood. (See also psychoanalysis.)... transference
A serious form of congenital heart disease in which the aorta and pulmonary artery are transposed. Open heart surgery is needed to correct the defect.... transposition of the great vessels
Also called cross-dressing, a persistent desire by a man to dress in women’s clothing.... transvestism
Transplantation of tissues or organs of the body are de?ned as an allotransplant, if from another person; an autotransplant, if from the patient him or herself – for example, a skin graft (see GRAFT; SKIN-GRAFTING); and a xenotransplant, if from an animal.
The pioneering success was achieved with transplantation of the kidney in the 1970s; this has been most successful when the transplanted kidney has come from an identical twin. Less successful have been live transplants from other blood relatives, while least successful have been transplants from other live donors and cadaver donors. The results, however, are steadily improving. Thus the one-year functional survival of kidneys transplanted from unrelated dead donors has risen from around 50 per cent to over 80 per cent, and survival rates of 80 per cent after three years are not uncommon. For a well-matched transplant from a live related donor, the survival rate after ?ve years is around 90 per cent. And, of course, if a transplanted kidney fails to function, the patient can always be switched on to some form of DIALYSIS. In the United Kingdom the supply of cadaveric (dead) kidneys for transplantation is only about half that necessary to meet the demand.
Other organs that have been transplanted with increasing success are the heart, the lungs, the liver, bone marrow, and the cornea of the eye. Heart, lung, liver and pancreas transplantations are now carried out in specialist centres. It is estimated that in the United Kingdom, approximately 200 patients a year between the ages of 15 and 55 would bene?t from a liver transplant if an adequate number of donors were available. More than 100 liver transplants are carried out annually in the United Kingdom and one-year-survival rates of up to 80 per cent have been achieved.
The major outstanding problem is how to prevent the recipient’s body from rejecting and destroying the transplanted organ. Such rejection is part of the normal protective mechanism of the body (see IMMUNITY). Good progress has been made in techniques of tissue-typing and immunosuppression to overcome the problem. Drugs are now available that can suppress the immune reactions of the recipient, which are responsible for the rejection of the transplanted organ. Notable among these are CICLOSPORIN A, which revolutionised the success rate, and TACROLIMUS, a macrolide immunosuppressant.
Another promising development is antilymphocytic serum (ALS), which reduces the activity of the lymphocytes (see LYMPHOCYTE) cells which play an important part in maintaining the integrity of the body against foreign bodies.
Donor cards are now available in all general practitioners’ surgeries and pharmacies but, of the millions of cards distributed since 1972, too few have been used. The reasons are complex but include the reluctance of the public and doctors to consider organ donation; poor organisation for recovery of donor kidneys; and worries about the diagnosis of death. A code of practice for procedures relating to the removal of organs for transplantation was produced in 1978, and this code has been revised in the light of further views expressed by the Conference of Medical Royal Colleges and Faculties of the United Kingdom on the Diagnosis of Brain Death. Under the Human Tissue Act 1961, only the person lawfully in possession of the body or his or her designate can authorise the removal of organs from a body. This authorisation may be given orally.
Patients who may become suitable donors after death are those who have suffered severe and irreversible brain damage – since such patients will be dependent upon arti?cial ventilation. Patients with malignant disease or systemic infection, and patients with renal disease, including chronic hypertension, are unsuitable.
If a patient carries a signed donor card or has otherwise recorded his or her wishes, there is no legal requirement to establish lack of objection on the part of relatives – although it is good practice to take account of the views of close relatives. If a relative objects, despite the known request by the patient, sta? will need to judge, according to the circumstances of the case, whether it is wise to proceed with organ removal. If a patient who has died is not known to have requested that his or her organs be removed for transplantation after death, the designated person may only authorise the removal if, having made such reasonable enquiry as may be practical, he or she has no reason to believe (a) that the deceased had expressed an objection to his or her body being so dealt with after death, or (b) that the surviving spouse or any surviving relative of the deceased objects to the body being so dealt with. Sta? will need to decide who is best quali?ed to approach the relatives. This should be someone with appropriate experience who is aware how much the relative already knows about the patient’s condition. Relatives should not normally be approached before death has occurred, but sometimes a relative approaches the hospital sta? and suggests some time in advance that the patient’s organs might be used for transplantation after death. The sta? of hospitals and organ exchange organisations must respect the wishes of the donor, the recipient and their families with respect to anonymity.
Relatives who enquire should be told that some post-mortem treatment of the donor’s body will be necessary if the organs are to be removed in good condition. It is ethical (see ETHICS) to maintain arti?cial ventilation and heartbeat until removal of organs has been completed. This is essential in the case of heart and liver transplants, and many doctors think it is desirable when removing kidneys. O?cial criteria have been issued in Britain to recognise when BRAIN-STEM DEATH has occurred. This is an important protection for patients and relatives when someone with a terminal condition
– usually as a result of an accident – is considered as a possible organ donor.... transplantation
The passage of liquid – called the transudate – through a membrane: for example, the passage of blood through the wall of a capillary vessel.... transudation
An anatomical description of a line, plane or structure at right-angles to the long axis of an organ or the body.... transverse
See TRANSFUSION – Transfusion of blood.... autologous blood transfusion
The insertion of a piece of bone from another site or from another person to ?ll a defect, provide supporting tissue, or encourage the growth of new bone.... bone transplant
See TRANSFUSION.... cell salvage transfusion
See TRANSFUSION.... continuous autologous transfusion
An operation in which a patient’s diseased lungs and heart are removed and replaced with donor organs from someone who has been certi?ed as ‘brain dead’ (see BRAIN-STEM DEATH). As well as the technical diffculties of such an operation, rejection by the recipient’s tissues of donated heart and lungs has proved hard to overcome. Since the early 1990s, however, immunosuppressant drug therapy (see CICLOSPORIN; TRANSPLANTATION) has facilitated the regular use of this type of surgery. Even so, patients receiving transplanted hearts and lungs face substantial risks such as lung infection and airway obstruction as well as the long-term problems of transplant rejection.... heart-lung transplant
UK legislation that lays down the framework and rules governing organ transplantation. The UK Transplant Support Service Authority (UKTSSA), a special health authority set up in 1991, is responsible for administering the NHS Organ Donor Registry and the Act (see APPENDIX 7: STATUTORY ORGANISATIONS).... human organs transplants act
See REVERSE TRANSCRIPTASE INHIBITOR.... nucleoside reverse transcriptase inhibitor
See TRANSPLANTATION.... organ transplantation
A technique for displaying the bile ducts (see BILE DUCT) and pancreatic ducts (see PANCREAS) with radio-opaque dyes. These are introduced via a catheter (see CATHETERS) inserted into the ducts through an incision in the skin. An X-ray is then taken of the area.... percutaneous transhepatic cholangiopancreatography (ptc)
These have almost completely replaced BONE MARROW TRANSPLANT, used to treat malignancies such as LEUKAEMIA and LYMPHOMA for the past 20 years. The high doses of CHEMOTHERAPY or RADIOTHERAPY used to treat these diseases destroy the bone marrow which contains stem cells from which all the blood cells derive. In 1989 stem cells were found in the blood during recovery from chemotherapy. By giving growth factors (cytokines), the number of stem cells in the blood increased for about three to four days. In a peripheral-blood stem-cell transplant, these cells can be separated from the peripheral blood, without a general anaesthetic. The cells taken by either method are then frozen and returned intravenously after the chemotherapy or radiotherapy is completed. Once transplanted, the stem cells usually take less than three weeks to repopulate the blood, compared to a month or more for a bone marrow transplant. This means that there is less risk of infection or bleeding during the recovery from the transplant. The whole procedure has a mortality risk of less than 5 per cent – half the risk of a bone marrow transplant.... peripheral-blood stem-cell transplants
An agent that prevents the action of the viral ENZYME, REVERSE TRANSCRIPTASE, so disrupting the virus’s colonisation of its target host. The reverse transcriptase inhibitor ZIDOVUDINE is used (in combination with other agents) to treat HIV infection.... reverse transcriptase inhibitor
Before the advent of small-bowel transplants, long-term intravenous feeding (total parenteral nutrition or TPN) was the last option for patients with chronic intestinal failure. Most recipients are children, and small-bowel transplantation is currently reserved for patients unable to continue on long-term parenteral nutrition. The main constraints to small-bowel transplantation are the intensity of rejection (necessitating high levels of immunosuppression), and the lack of donors who are the same size as the recipient (a particular problem for children).... small-bowel transplantantion
The psycho-sexual condition characterised by feelings of belonging to the gender opposite to that of the genitalia and the secondary sex characteristics. Subjects may be helped by counselling, drug therapy and in some circumstances an operation to change their physical sexual characteristics. Trans-sexuals or their families wanting help and guidance should contact the Gender Identity Consultancy.... trans-sexualism
An operation, usually done under local anaesthetic, in which the lining membrane of the UTERUS (womb) is excised using a type of LASER or DIATHERMY surgery that utilises a hysterescope (a variety of ENDOSCOPE) through which the operator can visualise the inside of the uterus. The operation is done to treat MENORRHAGIA (heavy blood loss during MENSTRUATION) and its introduction has reduced the need to perform HYSTERECTOMY for the condition.... transcervical resection of endometrium (tcre)
A method of electrical stimulation that is being used for the relief of PAIN, including that of MIGRAINE, NEURALGIA and phantom limbs (see AMPUTATION). Known as TENS, its mode of action appears to have some resemblance to that of ACUPUNCTURE. Several controlled trials suggest that it provides at least a modicum of relief of pain after operations, thereby reducing the amount of ANALGESICS that may be called for.... transcutaneous electrical nerve stimulation (tens)
Episodes of transient ISCHAEMIA of some part of the cerebral hemispheres or the brain stem (see BRAIN) lasting anything from a few minutes to several hours and followed by complete recovery. By de?nition, the ischaemic episode must be less than 24 hours. These episodes may be isolated or they may occur several times in a day. The cause is ATHEROMA of the carotid or vertebral arteries (see ARTERIES, DISEASES OF) and the embolisation (see EMBOLISM) of PLATELETS or CHOLESTEROL. These attacks present with strokes (see STROKE) that rapidly recover.... transient ischaemic attacks or episodes (tia, tie)
A type of short-term care provided by some long-term care facilities and hospitals, which may include rehabilitation services, specialized care for certain conditions (such as stroke and diabetes) and/or post-surgical care and other services associated with the transition between hospital and home.... transitional care
Sexually transmitted diseases – traditionally called venereal diseases – are infections transmitted by sexual intercourse (heterosexual and homosexual). In the United Kingdom they are treated in genito-urinary medicine (GUM) clinics. The incidences of these diseases are more common among people who have several sexual partners, as STDs are very infectious; some of the major STDs, particularly AIDS/HIV, are also transmitted by blood and so can result from needle-sharing by drug addicts, or by TRANSFUSION. The ‘traditional’ STDs – SYPHILIS, GONORRHOEA and CHANCROID – now comprise only 10 per cent of all such diseases treated in STD clinics: these clinics also treat patients with CHLAMYDIA, TRICHOMONIASIS, HERPES GENITALIS, MOLLUSCUM CONTAGIOSUM and genital WARTS. SCABIES and pubic lice (see PEDICULOSIS – Pediculus pubis) can also be transmitted by sexual intercourse, and HEPATITIS B is also recognised as an STD.
The incidence of STDs rose sharply during World War II but the advent of PENICILLIN and subsequent antibiotics meant that syphilis and gonorrhoea could be treated e?ectively. The arrival of oral contraception and more tolerant public attitudes to sexual activities resulted in an increase in the incidence of sexually transmitted infections. The diagnosis of NONSPECIFIC URETHRITIS (NSU), once given to many patients whose symptoms were not due to the traditional recognised infections, was in the 1970s realised to be wrong, as the condition was proved to be the result of infection by chlamydia.
Most STDs are treatable, but herpes is an infection that could become chronic, while hepatitis B and, of course, AIDS/HIV are potentially fatal – although treatment of HIV is now proving more e?ective. As well as the treatment and subsequent monitoring of patients with STDs, one of the important functions of clinics has been the tracing, treatment and follow-up of sexual contacts of infected individuals, a procedure that is conducted con?dentially.
Apart from AIDS/HIV, the incidence of STDs fell during the 1980s; however in some countries the agents causing syphilis and gonorrhoea began to develop resistance to antibiotics, which showed the continued importance of practising safe sex – in particular by restricting the number of sexual partners and ensuring the regular use of condoms. In the United Kingdom the rates per million of the male population infected by syphilis rose from 8.8 in 1991 to 9.7 in 1999; in females the ?gures were 4.0 to 4.5, respectively. For gonorrhoea, the ?gures for men were 399.4 in 1991 and 385 in 1999, with women also showing a reduction, from
216.5 to 171.3. In 1991, 552.6 per million of men had chlamydia, a ?gure which rose to
829.5 in 1999; for women in the same period the incidence also rose, from 622.5 to 1,077.1 per million. For genital herpes simplex virus, the infection rate for men fell from 236.6 per million to 227.7, whereas the ?gures for women showed a rise, 258.5 to 357. The incidence of AIDS/HIV is given under the relevant entry. (These ?gures are based on information in United Kingdom Health Statistics, 2001 edition, UKHSI, published by the O?ce of National Statistics.)... sexually transmitted diseases (stds)
Also called transvestism. The term given to a psycho-sexual condition in which there is a repetitive compulsion to dress in the clothes of the opposite sex to achieve ORGASM.... transvestitism
The use of a person’s own blood, donated earlier, for blood transfusion. Autologous transfusion eliminates the slight but serious risk of contracting a serious infectious illness from contaminated blood. There is no risk of a transfusion reaction occurring as a result of incompatibility between donor and recipient blood. Up to 3.5 litres of blood can be removed and stored in several sessions at least 4 days apart and up to 3 days before planned surgery. Blood may be salvaged during surgery, filtered and returned to the circulation, reducing the need for transfusion of donated blood.... blood transfusion, autologous
See corneal graft.... corneal transplant
Another term for kidney transplant.... renal transplant
A class of drugs used in the treatment of diseases, including HIV infection, that are caused by retroviruses. The drugs affect the ability of the virus to reproduce by blocking reverse transcriptase, a key enzyme. Drugs include lamivudine, zidovudine (AZT), efavirenz, and stavudine.... reverse transcriptase inhibitors
A method of administering a drug through the skin. The drug is released from the patch over a period of time and is absorbed by the skin.... transdermal patch
See blood transfusion, autologous.... transfusion, autologous
In the UK, this NHS authority (UKTSSA) provides a 24-hour service for matching, allocating and distributing organs. It is also responsible for keeping the records of all patients awaiting transplants. Established in 1991, the authority allocates donor organs without favour, following protocols set by advisory groups. It also administers the Human Organ Transplant Act on behalf of the Department of Health. (See TRANSPLANTATION.)... transplant support services authority
Any mechanism by which a susceptible human host is exposed to an infectious or parasitic agent. These mechanism are:- 1. Direct transmission Direct and essentially immediate transfer of infectious agents (other than from an arthropod in which the organism has undergone essential multiplication or development) to a receptive portal of entry by which infection of humans may take place. This may be by touching, as in kissing, sexual intercourse or biting (direct contact); or by the direct projection of droplet spray onto the conjunctivae, or onto the mucous membranes of the nose or mouth during sneezing, coughing, spitting or talking (usually not possible over a distance greater than 3 ft) (droplet spread); or, as in the systemic mycoses, by direct exposure of susceptible tissue to soil, compost or decaying vegetable matter that contains the agent and where it normally leads a saprophytic existence. 2. Indirect transmission (a) Vehicle-borne Contaminated materials or inanimate objects such as toys, handkerchiefs, soiled clothes, bedding (fomites), surgical instruments or dressing (indirect contact); water, food, milk, biological products including serum and plasma, or anysubstance serving as an intermediate means by which an infectious agent is transported and introduced into a susceptible host through a suitable portal of entry. The agent may or may not have multiplied or developed in or on the vehicle before being introduced into man. (2) Vector-borne (i) Mechanical:- Includes simple mechanical carriage by a crawling or flying insect through soiling of its feet or proboscis, or by passage of organisms through its gastrointestinal tract. This does not require multiplication or development of the organism. (ii) Biological:- Propagation (multiplication), cyclic development, or a combination of them (cyclopropagation) is required before the arthropod can transmit the infective form of the agent to man. An incubation period (extrinsic) is required following infection before the arthropod becomes infective. Transmission may be by saliva during biting, or by regurgitation or deposition on the skin of agents capable of penetrating subsequently through the bite wound or through an area of trauma following scratching or biting. This is transmitted by an infected invertebrate host and must be differentiated for epidemiological purposes from simple mechanical carriage by a vector in the role of a vehicle. An arthropod in either role is termed a vector. (c) Air-borne The dissemination of microbial aerosols with carriage to suitable portal of entry, usually the respiratorytract. Microbial aerosols are suspensions in air of particles consisting partially or wholly of microorganisms. Particles in the 1 to 5 micron range are quite easily drawn into the lungs and retained there. They may remain suspended in the air for long periods of time, some retaining and others losing infectivity of virulence. Not considering as airborne are droplets and other large particles, which promptlysettle out; the following are airborne, their mode of transmission indirect: (i) Droplet nuclei: Usually the small residues which result from evaporation of droplets emitted by an infected host. Droplet nuclei also may be created purposely by a variety of atomising devices, or accidentally, in microbiology laboratories or in abattoirs, rendering plants, autopsy rooms, etc. They usuallyremain suspended in the air for long periods of time. (ii) Dust: The small particles of widely varying size which may arise from contaminated floors, clothes, beddings, other articles; or from soil (usually fungus spores separated from dry soil by wind or mechanical stirring). Note: Air conditioning and similar air circulating systems may play a significant role in air-borne transmission (e.g. Legionnaire’s disease).... transmission
A term meaning capable of being passed from one person, or one organism, to another.... transmissible
A rare disorder in which a person wishes to live as a member of the opposite sex. Transsexuals commonly seek hormonal or surgical treatment to bring about a physical sex change. A psychiatric evaluation and a physical examination are necessary before such treatment is undertaken.... transsexualism
A type of in vitro fertilization, also referred to as , in which ova are fertilized outside the body and returned to a fallopian tube rather than to the uterus.... zygote intrafallopian transfer
(in biochemistry) an energy-dependent process in which certain substances (including ions, some drugs, and amino acids) are able to cross cell membranes against a concentration gradient. The process is inhibited by substances that interfere with cellular metabolism (e.g. high doses of digitalis).... active transport
An animal merely acting as a transporter for a parasite, c.f. Paratemic host.... transport host
A system operated to transfer a patient or client to or from a health care facility and place of residence.... transportation service
The use of a special CYSTOSCOPE (a resectoscope) inserted through the URETHRA to resect the PROSTATE GLAND or bladder tumours. (See also RESECTION.)... transurethral resection
see transposition of the great vessels.... congenitally corrected transposition
mechanical obstruction of labour in which the fetal head is unable to rotate from occipitotransverse to occipitoanterior position (see occiput).... deep transverse arrest
a series of enzymes and proteins in living cells through which electrons are transferred, via a series of oxidation-reduction reactions. This ultimately leads to the conversion of chemical energy into a readily usable and storable form. The most important electron transport chain is the respiratory chain, present in mitochondria and functioning in cellular respiration.... electron transport chain
(GOT) see aspartate aminotransferase.... glutamic oxaloacetic transaminase
(GPT) see alanine aminotransferase.... glutamic pyruvic transaminase
see orthotopic transplantation.... heterotopic transplantation
the spread of an infectious agent from one person or group to another, usually through contact with contaminated material, such as sputum or faeces. Compare vertical transmission.... horizontal transmission
a new technique still under evaluation for curing type 1 *diabetes mellitus, which involves the injection of donated cells from the pancreatic *islets of Langerhans into the liver, where it is hoped they will seed and survive. The transplanted cells then take over insulin production from the recipient’s diseased pancreas.... islet cell transplantation
the process by which cilia (see cilium) move a thin film of *mucus from the upper and lower respiratory tracts towards the digestive tract. Particles of dust and microorganisms are trapped on the mucus and thereby removed from the respiratory tract.... mucociliary transport
(NT scanning) an ultrasound screening test performed during pregnancy at 11 weeks of gestation that measures the maximum thickness of the translucency between the skin and the soft tissue overlying the cervical (neck) region of the spine of the fetus. Increased NT is associated with an increased risk of chromosomal abnormalities and of a wide variety of structural abnormalities (e.g. heart defects). See also ultrasound marker.... nuchal translucency scanning
transplantation of a donor organ or tissue (usually the liver) into a recipient at the site where the recipient’s organ has been removed. In contrast, heterotopic transplantation involves the preservation of the recipient’s organ in its natural site and the addition of the donor organ at another site.... orthotopic transplantation
imaging of the bile duct and pancreatic duct. A catheter is carefully manipulated into the ducts via direct puncture through the abdomen under radiological guidance. Contrast material is flushed through the catheter to delineate the ducts (see also cholangiography). This procedure is often performed in cases of obstructive jaundice prior to insertion of a biliary drain or stent when *ERCP is not possible.... percutaneous transhepatic cholangiopancreatography
see transplantation.... renal transplantation
(rTMS) see transcranial magnetic stimulation.... repetitive transcranial magnetic stimulation
(STD) any disease transmitted by sexual intercourse, formerly known as venereal disease. STDs include *AIDS, *syphilis, *gonorrhoea, some *Chlamydia infections, genital *herpes, and *soft sore. The medical specialty concerned with STDs is genitourinary medicine.... sexually transmitted disease
n. an enzyme that catalyses the transfer of an amino group from an amino acid to an ?-keto acid in the process of *transamination. Examples include *aspartate aminotransferase (AST), which catalyses the transamination of glutamate and oxaloacetate to ?-ketoglutarate and aspartate, and *alanine aminotransferase (ALT), converting glutamate and pyruvate to ?-ketoglutarate and alanine.... transaminase
n. a process involved in the metabolism of amino acids in which amino groups (–NH2) are transferred from amino acids to certain ?-keto acids, with the production of a second keto acid and amino acid. The reaction is catalysed by enzymes (see transaminase), which require pyridoxal phosphate as a coenzyme.... transamination
(TEMS) a minimally invasive surgical procedure for rectal polyps not suitable for colonoscopic resection. For early rectal cancer it can be an alternative to lower anterior resection of the rectum. The procedure is performed through the anus and rectum using an *operating microscope and microsurgical instruments.... transanal endoscopic microsurgery
(TACE) an *interventional radiology procedure to treat liver cancer in which a chemotherapeutic agent (usually doxyrubicin) loaded onto tiny beads is directly delivered to the cancerous area. This involves passing a catheter through the femoral artery in the groin and selectively placing it into the hepatic artery. A minute catheter (microcatheter) is then placed through the existing catheter and advanced more selectively into the area of cancer. Thus, the chemotherapy-loaded beads can be administered directly to the cancer, where they can not only treat it but also block the blood supply to that area (*embolization).... transarterial chemoembolization
(TAVI) replacement of the aortic valve in patients with *aortic stenosis using a catheter-delivered prosthesis rather than open heart surgery. Usually the catheter is passed via the femoral artery, but sometimes it can be passed via the subclavian artery or through the wall of the left ventricle via a localized *thoracotomy.... transcatheter aortic valve implantation
(TCRE) an operation, which is performed under local anaesthetic, in which the membrane lining the uterus (see endometrium) is cut away by a form of *electrosurgery using a *resectoscope, which is introduced through the cervix. Like *endometrial ablation, TCRE is used as an alternative to hysterectomy to treat abnormally heavy menstrual bleeding as it results in fewer complications and shorter stays in hospital.... transcervical resection of the endometrium
a route of tumour *metastasis across a body cavity, such as the pleural, pericardial, or peritoneal cavity. Transcoelomic spread commonly occurs in advanced cancers of the lung, stomach, colon, ovary, and endometrium. It may be associated with the development of a malignant *effusion.... transcoelomic spread
(TMS) stimulation of the brain by strong magnetic fields that induce electric currents in the underlying brain tissue. Repetitive transcranial magnetic stimulation (rTMS), consisting of a series of TMS pulses, is used to treat depression. Its clinical utility is controversial, with inconsistent research results regarding its efficacy. Although there have been some small studies regarding its use with other conditions, such as OCD, rTMS is not currently used routinely in the treatment for any illness other than depression.... transcranial magnetic stimulation
n. the process in which the information contained in the *genetic code is transferred from DNA to RNA: the first step in the manufacture of proteins in cells. See messenger RNA; translation.... transcription
n. a device used to convert one form of signal into another, allowing its measurement or display to be made appropriately. For example, an *ultrasound probe converts reflected ultrasound waves into electronic impulses, which can be displayed on a TV monitor.... transducer
n. the transfer of DNA from one bacterium to another by means of a *bacteriophage (phage). Some bacterial DNA is incorporated into the phage. When the host bacterium is destroyed the phage infects another bacterium and introduces the DNA from its previous host, which may become incorporated into the new host’s DNA.... transduction
n. 1. a cross section of a piece of tissue. 2. cutting across the tissue of an organ (see also section).... transection
n. the direct transfer of DNA molecules into a cell.... transfection
n. an enzyme that catalyses the transfer of a group (other than hydrogen) between a pair of substrates.... transferase
(siderophilin) n. a *glycoprotein, found in the blood plasma, that is capable of binding iron and thus acts as a carrier for iron in the bloodstream.... transferrin
a type of RNA whose function is to attach the correct amino acid to the protein chain being synthesized at a *ribosome. See also translation.... transfer rna
the area of the *cervix of the uterus where the squamous epithelium, which covers the vaginal portion of the cervix, joins with the columnar epithelium, which forms the lining (endocervix) of the cervical canal.... transformation zone
(TGF) a protein – a *cytokine – that controls growth, proliferation, and other functions in most cells. It plays a role in asthma and other respiratory diseases and is also involved in diseases elsewhere in the body. There are two classes: TGF-? and TGF-?.... transforming growth factor
adj. describing the condition of one who firmly believes that he or she belongs to the gender opposite to his or her biological sex. A transgender person will often seek gender reassignment, i.e. to be legally recognized as belonging to the gender opposite to that on his or her birth certificate. The transition may involve hormone treatment and/or surgery but there is no requirement for this. Under current UK law, the person must supply evidence that he or she has been medically diagnosed with *gender dysphoria, has lived in his or her acquired gender for the past two years, and intends to remain in it until death. A proposed reform to the law would replace this process with one of simple self-declaration (although this idea has aroused some opposition). ‘Transgender’ is now preferred to the older term transsexual, as this refers more narrowly to those who have undergone surgery to change gender. See also gender dysphoria.... transgender
adj. through the liver: describing a procedure or investigation in which access to the biliary system is gained by this route (e.g. *percutaneous transhepatic cholangiopancreatography).... transhepatic
a form of cancer that affects the urothelium, which lines the urinary collecting system of the kidney, ureters, bladder, and the proximal part of the urethra. It is the most common type of bladder cancer.... transitional cell carcinoma
adj. through the jugular vein: a route commonly taken to gain access to the venous system to place lines or undertake interventions (e.g. IVC filter insertion and transjugular liver biopsies).... transjugular
n. (in cell biology) the manufacture of proteins in a cell, which takes place at the ribosomes. The information for determining the correct sequence of amino acids in the protein is carried to the ribosomes by *messenger RNA, and the amino acids are brought to their correct position in the protein by *transfer RNA.... translation
a type of scientific enquiry that focuses on developing practical application from the findings from basic scientific research. The field of translational research is sometimes described as comprising T1 research and T2 research. The former focuses on developing novel clinical treatments from laboratory-based basic science; the latter on embedding the findings of clinical trials into everyday practice. See also academic health science network.... translational research
n. the process whereby an amino acid donates its terminal methyl (?CH3) group for the methylation of other compounds. Methionine is the principal methyl donor in the body and the donated methyl group may subsequently be involved in the synthesis of such compounds as choline or creatinine or in detoxification processes.... transmethylation
n. the act of passing through or across, e.g. the passage of blood cells through the intact walls of capillaries and venules (see diapedesis).... transmigration
a *myocardial infarction that involves the full thickness of the left ventricular wall.... transmural myocardial infarction
(TOT) see tension-free vaginal tape.... transobturator tape
(TOE) see echocardiography.... transoesophageal echocardiography
(TORS) a form of robot-assisted surgery used for treating difficult-to-access tumours of the pharynx and larynx.... trans-oral robotic surgery
n. the abnormal positioning of a part of the body such that it is on the opposite side to its normal site in the body. For example, it may involve the heart (see dextrocardia).... transposition
(TRUS) an *ultrasonography technique for examination of the prostate gland and seminal vesicles by placing an ultrasound probe through the anus to lie directly behind these structures in the rectum. Because of the close proximity of the probe, excellent detail is seen. The technique enables transrectal or transperineal biopsies of the prostate to be taken in a systematic manner in the diagnosis of cancer. See also vesiculography.... transrectal ultrasonography
a procedure in which, under X-ray guidance, a sharp-tipped catheter positioned in the heart is used to create a small hole in the partition (septum) separating the atria. This allows other catheters to be passed from the right to the left atrium for the purposes of pressure measurement, *ablation, or *valvuloplasty.... transseptal puncture
n. see transgender.... transsexual
resistance to the flow of electricity through the heart muscle during *defibrillation due to the thoracic structures lying between the defibrillation paddles and the heart. These structures include the skin and soft subcutaneous tissues, the ribs and sternum, the lungs, and the pericardium. The best way to reduce the impedance, and thus to deliver the maximum available current to the heart, is to use defibrillation gel pads (see coupling agents), to deliver the shock when the lungs are empty of air, or to press firmly down if using hand-held paddles. Transthoracic impedance is usually between 70 and 80 ohms.... transthoracic impedance
adj. across the eardrum. This can refer to the injection of medication through the eardrum into the middle ear cavity (see intratympanic) to treat conditions of the inner ear or the insertion of an electrode through the eardrum to perform *electrocochleography.... transtympanic
n. the operation of connecting one ureter to the other in the abdomen. The damaged/obstructed ureter is cut above the diseased or damaged segment and joined end-to-side to the other ureter.... transuretero-ureterostomy
(TURP) see resection.... transurethral resection of the prostate
(TUVP) a technique that vaporizes (rather than resects) prostate tissue; it is associated with less bleeding during the procedure. TUVP is used to treat *lower urinary tract symptoms thought to be due to benign prostatic hyperplasia (see prostate gland) or urinary retention.... transurethral vaporization of the prostate
(TVT) see tension-free vaginal tape.... transvaginal tape
an *ultrasonography technique for examination of the female pelvis using a vaginal probe instead of an abdominal transducer. It allows the use of a higher frequency, thus providing superior resolution and therefore a more detailed anatomy of the female pelvis and an earlier and more accurate identification of fetal structures.... transvaginal ultrasonography
the long projection from the base of the neural arch of a *vertebra.... transverse process
1. (mother-to-child transmission) transmission of an infection, such as HIV, hepatitis B, or hepatitis C, from mother to fetus via the placental circulation. 2. (in population genetics) inheritance of an allele or condition from either the father or mother.... vertical transmission
(TTTS) a condition in which communicating vessels in the shared placenta of monochorionic twins (see chorionicity) divert blood to one fetus (the recipient) from the other (the donor), resulting in one fetus with increased blood volume and one anaemic fetus. It complicates 15% of monochorionic twin pregnancies, and a system of ultrasound staging has been developed to assess the severity of the syndrome. TTTS is associated with a high perinatal mortality rate. There is significant morbidity and poor neurodevelopmental outcome in surviving infants due to complications of the disease itself and the high preterm birth rate that invariably accompanies this condition. A range of treatments, including *amnioreduction, *septostomy, and laser ablation of the communicating vessels, have led to an improvement in overall perinatal survival rates.... twin-to-twin transfusion syndrome
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