Glossary
Starting with A for "ACE inhibitor" and continuing through to Y for "Yolk Sac Tumour", we give you succinct explanations for scientific and medical terms in clear and simple words.
- I.U.Abbreviation for 1. Insulin unit; 2. International unit, e.g. for enzymatic activity or the quantity of an antibiotic which just inhibits the growth of a test bacterium when dissolved in 1 ml of culture medium. If the substance is chemically pure, the information is given in weight units (gram, milligram, nanogram), independently of the test method (absolute mass unit).
- Icterus gravidarumalso known as Hepatopathia gravidarum, the Latin expression for jaundice of pregnancy.
There are two different forms of jaundice of pregnancy:
1. Icterus in graviditate (jaundice during pregnancy in which the cause is unrelated to the pregnancy)
This condition occurs in acute inflammation of the liver (Acute Hepatitis), acute destruction of liver cells, cirrhosis of the liver, jaundice from obstruction by gallstones and lysis of the red blood cells.
2. Icterus e graviditate (jaundice as a result of the pregnancy, in which the cause is related to the pregnancy itself). This condition occurs in acute fatty liver, in toxaemia of pregnancy (gestosis) with the HELLP syndrome (lysis of red blood cells and raised liver values) and in biliary stasis (congestion) within the liver. The latter condition is sometimes observed after the hormonal contraceptive pill. The premature birth rate is then 20% and the neonatal mortality 10%. - IDLAbbreviation for intermediate density lipoproteins
Lipoproteins of intermediate density, which are involved in the transport and distribution of cholesterol. IDLs are the precursors of the LDLs (low density lipoproteins) and are formed from VLDLs (very low density lipoproteins). - Immune DefenceAbility of the immune system of an organism to react specifically against antigens with the help of specific antibodies (humoral immunity) or of T-lymphocytes, which can destroy cells which are foreign to the body (cell-mediated immunity).
- Immune Deficiency Syndrome, Acquiredsee AIDS.
- Immune deficiency Virus, Humansee HIV.
- Immune SystemThe human immune system has the task of protecting the body against foreign substances and altered body cells, such as cancer cells, and to keep the body healthy in this way. This protection is carried out with specialised white blood cells (cf. phagocytes, B-cells, T-cells) and through the formation of antibodies.
- ImmunityLack of susceptibility of the organism to an infection with specific pathogens and protection from the action of certain toxins by protective mechanisms. A distinction is made between:
1. Non-specific immunity: Mechanisms which are always present to protect the body against foreign substances; e.g. skin, mucous membrane, cells and chemical substances in the body which act against pathogens or toxins. Functional non-specific immunity is the reason that man does not fall ill from certain diseases, such as distemper.
2. Specific immunity: protective mechanisms which develop after contact with a pathogen or toxin. After the first contact, specific defensive cells are formed, which contain information for defence against specific pathogens or toxins and which may last a lifetime. Active inoculation is carried out by administering killed or attenuated pathogens and causes the development of specific immunity to the pathogen.
- Impotencesee Erectile disturbance
- in vivowithin the living body
- incidencethe number of new cases of a specific event or disease occurring in a population during a specified period of time
- Indirect measurement of blood pressurealso known as non-invasive measurement of blood pressure.
Indirect measurement of blood pressure by the method of Riva-Rocci (1896) is usually performed with an inflatable rubber cuff which encloses the upper arm. This is connected to a manometer and is inflated until the pulse in the artery which runs along the radius (radialis pulse) is no longer palpable near the wrist. The pressure in the cuff is slowly reduced by releasing air and the systolic blood pressure is determined by feeling the radialis pulse, as the first pulse beat can be felt when the arterial pressure has just exceeded the cuff pressure. Alternatively the systolic and diastolic pressures are determined by listening for Korotkoff's sound in the elbow. There are semi-automatic and electronic systems for the patient to measure his own blood pressure. Continuous out-patient measurement of blood pressure at defined intervals (24 h registration) allows the assessment of changes in blood pressure under daily conditions. Cf. high blood pressure. - Infarctdeath of tissue due to an interruption of the supply of oxygenated blood; an example is myocardial infarction, in which blockage of a coronary artery results in death of a portion of the heart muscle
Necrosis, i.e. irreversible change to cells with consequent death of part of an organ or tissue. Results from ischaemia from acute arterial occlusion, when there is no shunt circulation to compensate for the occlusion. Infarcts are mostly wedge shaped, with the point directed towards the occlusion, and correspond to the area served by the occluded artery.
- InfectionTransmission, adherence and penetration of microorganisms (viruses, bacteria, fungi and other) into a so-called host (plant, animal, man), followed by reproduction in the host. An infection is the precondition for the development of an infectious disease and is essentially determined by the infectious properties of the microorganism, such as transmissibility, adherence, ability to penetrate and ability to reproduce. The emergence and course of an infectious disease also depend on the susceptibility or lack of susceptibility of the host and from the defences of the host (immunity). Influenza is the result of a viral infection.
- Infection, influenzalUnspecific collective term for generalised feverish illness from different causes, mostly with more or less marked participation of the upper respiratory tract or (more rarely) of the gastrointestinal tract. See colds, influenza.
- Infections, OpportunisticInfection with microorganisms which do not cause disease in healthy individuals.
The infective agents of opportunistic infections are dangerous for individuals with immune deficiency diseases (e.g. AIDS) or to those taking immunosuppressive therapy (e.g. after organ transplantation).
Frequent opportunistic infections in AIDS patients include pneumonia from the infective agents Pneumocystis carinii and Aspergillus fumigatus or infection with the cytomegaly virus. - Infections, Sexually TransmissibleInfectious diseases which are transmitted through sexual intercourse. These include AIDS, syphilis, gonorrhoea, certain inflammatory conditions in the genital region and hepatitis.
Occurrence: About 340 million new infections each year throughout the world. Individuals between 20 and 24 years are most strongly affected. - inflammationa tissue reaction to injury or irritation, characterised by mobilisation of white blood cells and antibodies, swelling and fluid accumulation; inflammation may involve a specific organ or tissue or the entire body and can be acute or chronic
- Inflammation of the Middle Earsee otitis media
- InfluenzaDefinition
Also known as viral influenza or flu
Influenza is an acute endemic, epidemic or pandemic infection of the respiratory tract. (Cf. endemic disease, epidemic, pandemic).
Causes
Pathogen
Influenza is caused by the so-called influenza virus. Influenza or flu viruses are of types A, B and C. Type A influenza virus is responsible for the intense waves of influenza,as it is highly variable (see antigenic drift, antigenic shift). The viruses are transmitted by droplet infection (sneezing and coughing), but also by speaking and direct contact. After an infection, they destroy the uppermost layer of the mucous membrane from the nose to the bronchi. As a result, secondary bacterial infections can arise, particularly with Haemophilus influenzae, staphylococci and streptococci. Cf. viruses.
Symptoms
Influenza begins suddenly with high fever, chills, throat problems, and pain in the head, limbs, muscles and lower back. Additional symptoms are hoarseness and dry cough and sometimes vomiting and abdominal pain. Any organ or organ system can be toxically damaged, which can lead to the occurrence of different symptoms: excessively low blood pressure, slow heart rate, swelling of the liver, nose bleeds, coughing blood and influenza exanthema. If the course is uncomplicated, the symptoms regress after 4-8 days. Total recovery can last longer.
Complications
Complications may develop, particularly in older people and when there are secondary bacterial infections. These include:
1. Acute bronchitis and pneumonia, which is regarded as the cause of 80-100 % of influenza deaths. Secondary infections with staphylococci may lead to accumulation of pus in the pleura. 2. Paranasal sinusitis and otitis media. 3. Circulatory failure as a result of infectious and toxic inflammation of the heart muscle or damage to the smallest blood vessels (capillaries). 4. Involvement of the nervous system (inflammation of the nerves, meningitis).
Diagnosis
Diagnosis is carried out on the basis of the symptoms. Additional diagnostic tests can include the blood count, demonstration of the virus in secretions in the throat or in the stool and measurement of antibodies. Influenza should be differentiated from other viral infections, particularly adeno- and Coxsackie viruses, and also ornithosis, which is an infectious bacterial disease transmitted by birds, sepsis, Typhus abdominalis and miliary tuberculosis.
Therapy
As a first step, the symptoms are combated with drugs to reduce the fever and inflammation. If the course of the disease is threatening, treatment follows with a vaccine which contains the corresponding antibody and with virostatic drugs. antibiotics are used for secondary bacterial infections. In cases free of complications the prognosis is favourable.
Prevention
protective vaccination to influenza can be carried out as prophylaxis against infection. Vaccination is particularly important for individuals aged over 60, those who are at increased risk because of an underlying disease and for people who are at increased risk because of their work, e.g. if they work in hospitals or have much contact with the public. It is best to use the antigen combination which is currently recommended by the WHO. If at all possible, the vaccination should be carried out in autumn before the start of the influenza season. It is best to inject the vaccine into the upper arm. Revaccination should be carried out every year, as vaccination only protects for a maximum of one year. During a pandemic caused by a change in the pathogenic influenza virus (cf. antigenic shift), vaccination with broad activity is requisite. This can be of great value for the health of the population. The use of the protective vaccine depends on the epidemic situation. - Influenza EnanthemaInflammatory changes in the mucous membrane in connection with influenza; small blisters in the frontal arch of the palate, very small point-like areas of bleeding from the small blood vessels, particularly on the mucous membrane of the cheeks, or small yellow-white specks (flu points) on the mucous membrane of the cheeks, at the border between the red of the lips and the lip mucous membrane. Cf. influenza exanthema.
- Influenza ExanthemaInflammatory changes in the skin (resembles measles) in the context of influenza more frequent in children than in adults. Influenza exanthema arises on the first day of the illness and remains for one to two days. Cf. influenza enanthema.
- Influenza Virusalso known as flu virus
Virus which causes influenza. Divided into types A, B and C on the basis of an antigenically active protein. Type A influenza viruses are further divided into subtypes on the basis of differences in the surface antigens localised in the virus coat, neuraminidase (N) and haemagglutinin (H) and are characterised by considerable antigenic variability (cf. antigenic drift, antigenic shift. They occur in man and also in pigs, birds and horses. 14 Different haemagglutinins and 9 different neuraminidases have been described. Haemagglutinins H1, H2 and H3 and neuraminidases N1 and N2 are of particular importance in the influenza viruses which are infective to man. For example, the Spanish flu was caused by influenza virus A of the subtype H1N1. However, in May 1997 the influenza virus A of subtype H5N1 was found in Hong Kong in a deceased child; previously only some species of bird had been infected with this virus. This led to intensive monitoring of this subtype till the end of 1997 and to the discovery of a further 15 cases of death in Hong Kong. It is presumed that the virus infection was caused by contact between humans and infected birds.
As a result of this marked antigenic variability, antibodies formed against the influenza virus in the course of a previous immunisation can lose their specificity for the antigen and hence their protective activity. The antigenic variability also hinders the development of a constant standard vaccine which is generally active. The virus is transmitted by droplet infection. Protective vaccination to influenza may be performed as a preventive measure. Cf. protective vaccination, viruses - Inoculationsee vaccine
- InsufficiencyInadequate performance of an organ
- InsulinHormone which is formed in the B-cells of the islets of Langerhans in the pancreas. Insulin reduces blood sugar and participates in the regulation of normal blood sugar to ca. 3.9 to 6.4 mmol/l (70 to 115 mg/dl). Insulin only acts on liver, muscle and fat tissue. In muscle and fat tissue, insulin is responsible for the transport of glucose and aminoacids into the cells. The cellular uptake of glucose causes a decrease in blood sugar concentrations. In all three tissues insulin supports both the production of glycogen, the storage form of glucose, and the synthesis of proteins (protein biosynthesis). Insulin also effects the transport of potassium ions into the cells. Lipolysis (fat breakdown) is inhibited by insulin. Under the influence of insulin, important enzymes for glucose breakdown (glycolysis) are prepared.
Therapy
Insulin is used for the therapy of insulin-dependent type 2 diabetes and type 1 diabetes, which are characterised by raised blood sugar (hyperglycaemia) and either a lack of insulin or inadequate insulin activity. During insulin treatment, antibodies to the insulin given can be formed, so that human insulin prepared by genetic engineering is to be preferred, particularly for newly regulated patients. The forms used have different time courses of action and include short acting insulin (so-called old insulin), insulin analogues and slow-release or depot insulin. Orally administered insulin is immediately destroyed by digestive enzymes, so that insulin therapy of type 1 or type 2 diabetes must circumvent the digestive tract, for example by injection under the skin or directly into the veins. Cf. insulin receptor, insulin resistance, carbohydrate metabolism. - Insulin antagonistsNatural substances involved in diabetic counterregulation, which are released at increased levels at low blood sugar concentrations (hypoglycaemia). Examples include glucocorticoids, glucagon, adrenalin and noradrenalin.
- Insulin infusion systemsElectrically driven pump systems for the continuously regulated long term infusion of insulin (and if desired glucose). Insulin is normally administered under the skin, into a flexible and thin plastic catheter which has been laid into a vein or through a port in the stomach area.
Significance
In patients with type 2 diabetes or type 1 diabetes, blood sugar can be adjusted to normal values, which are as constant as possible. With conventional treatment with insulin injections this can rarely be achieved. The continuous infusion of insulin, particularly in the night, presumably makes an essential contribution to the stabilisation of the metabolism. Even after completing treatment with the insulin infusion system, it is easier to regulate blood sugar. One explanation for this might be increased sensitivity of the insulin receptor as a result of metabolic optimisation.
Clinically relevant systems
1. Insulin and glucose infusion systems which are computer operated and controlled by blood sugar (closed loop systems). These imitate the natural release of insulin in a healthy individual and in principle consist of a glucose sensor to measure blood sugar, a computer to calculate the insulin dose which should be administered, in accordance with the settings, and the insulin-glucose dosing unit. This system is mostly used in hospitals, e.g. in diabetic coma, operations when diabetic women give birth and for new or rapid regulation of insulin-dependent diabetics. 2. Portable, battery driven insulin infusion systems without a glucose sensor (open loop systems). The so-called insulin pump allows not only continuous insulin infusion but adjustable treatment with insulin as required before and at meals, corresponding to the current blood sugar concentration measured by self-control. These systems can be removed for about one hour each day. If his blood sugar regulation is good, the patient can plan his day and his meals relatively freely.
Complications
Possible complications during long-term out-patient use include technical problems, such as a bend in the catheter or loss of the catheter, local pain or hardening.
- Insulin receptorBinding site for insulin on the cell membrane of liver, muscle and fat cells. After binding, insulin forms the insulin-receptor complex, which is taken up into the interior of the cell. The insulin-receptor complex causes increased uptake of glucose from blood into the cell, which decreases the concentration of sugar in the blood.
- Insulin resistanceInsulin resistance means that the interaction between insulin and insulin receptors is disturbed or inefficient. This perturbs the uptake of glucose from blood into cells. Insulin resistance is characterised by high insulin concentrations, in spite of normal or raised blood sugar concentrations.
Consequence
Increase in the requirement for insulin, up to 80 I.U. per day, for controlling metabolism in cases of type 2 diabetes. Cf. insulin sensitiser
- Insulin sensitiserInsulin sensitisers are antidiabetic drugs to reduce insulin resistance. They increase the uptake of blood sugar by muscle and fat tissue and are used for type 2 diabetes and metabolic syndrome.
- Insulin therapyTreatment of type 2 diabetes or Type 1 diabetes with insulin, with the aim of achieving satisfactory control of blood sugar concentrations, with less than 160 mg/dl before a meal and two hours after a meal.
Forms
1. Conventional insulin therapy. Usually a fixed scheme of 2-3 injections of a standard mixture of intermediate insulin (delayed action) and normal insulin (rapid action) in the morning and also possibly at noon and in the evening. This variant is not optimally adjustable to variable blood sugar values. 2. Intensified insulin therapy: Injection of intermediate insulin in the morning and late evening and also of normal insulin at meals. The dose of normal insulin is adjusted to the carbohydrate content of the food and the blood sugar concentration measured before the meal. This so-called basal-bolus principle is intended to imitate the release of insulin in healthy subjects. 3. Insulin therapy with an insulin infusion system.
Undesired drug side-effects
Low blood sugar (hypoglycaemia), changes in adipose tissue at the site of the injection, occasionally swelling. - Insulin tolerance testTest procedure for the diagnosis of insulin resistance, i.e. reduced activity of insulin.
Principle
After intravenous injection of 0.1 I.U. (International Unit) of insulin per kg body weight, the concentration of blood sugar normally sinks to maximally 40% of the initial value after 30 minutes. If there is insulin resistance, the blood sugar concentration only sinks at the higher dose of 0.3-1 I.U. per kg body weight, to maximally 80% of the initial value.
Complications
Hypoglycaemic shock; clinical supervision is necessary.
- Insulin unitAbbreviation I.U.
International unit for the quantity of insulin, which corresponds to the activity of a standard biological preparation of ca. 41.67 µg. 1 mg of crystallised insulin corresponds to 28 I.U..
- Insulin-glucose tolerance testDiagnostic test to examine the function of the hormone system which consists of the hypothalamus, pituitary and adrenal cortex, an important site of hormone production. The subject is treated with insulin and glucose and the blood sugar concentration measured at fixed intervals. In healthy individuals, the measured blood sugar first drops steeply and then clearly increases as a result of the counterregulation (rebound) by insulin antagonists. After three hours the blood sugar reaches its initial value again. In patients with pituitary disease or with poor function of the adrenal cortex the shape of the time course is flatter. As a result of decreased hormone activity, the changes in blood sugar concentration with time are less marked. Cf. diabetic counterregulation
- Interactionsalso drug interactions
Interactions occur between two or more drugs which are taken at the same time. Interactions may affect the intensity of drug action, its duration or its type. The change may be an increase or a decrease. These interactions may be dangerous in drugs which must be dosed very precisely, as they are then dangerous or inadequate. - Interferon, PegylatedChemically modified interferon, with longer and more intense activity
- InterferonsMessenger substances composed of protein, which are formed by cells after an infection with viruses or bacteria. Three major groups of interferons are formed in the body: alpha-Interferon in the white blood cells, beta-interferon in certain cells in connective tissue and gamma-interferon in the T-cells. Interferons act against viruses, inhibit cell growth and modify the immune system; depending on the situation they may stimulate it or suppress it. Interferons produced by genetic engineering are used to treat cancer and certain virus diseases (e.g. AIDS, chronic hepatitis).
- InterleukinMessenger substances of the immune system which are produced by white blood cells. They are responsible for the cytolytic (cell destroying) immune reaction which is triggered by T-cells and for antibody production from the activation of B-cells.
- Interleukin 2Abb. IL2
Interleukin* that is predominantly active in cell-mediated immunity. Interleukin 2 is formed by activated T-cells and activates T- and B-cells and natural killer cells (cf. T- killer cells). - Interval Therapyalso tablet interval, therapy interruption
Form of therapy in which there is deliberate interruption of the treatment with the drug. The aim of this interval is to keep the drug side effects within limits. Checks must be carried out during the interval, so that, for example, the virus load in an HIV infection does not become too large. - Intestinal LumenInternal channel of the intestine
- IntimaInnermost layer of the vessel wall of the arteries, veins and lymph vessels.
- Intimal fibrosisProliferation of connective tissue and the consequent thickening of the innermost tissue layer of blood vessels. It occurs, for example, in arteriosclerosis.
- Intimal oedemaConcentration of fluid in the innermost tissue layer of blood vessels which is caused by penetration of components of blood plasma. First stage of arteriosclerosis.
- intrinsic factora protein molecule produced in the lining of the stomach that facilitates intestinal absorption of vitamin B12; binds vitamin B12, thereby protecting it from breakdown in the intestine, and aids its transport for storage in the liver
- InulinPlant storage carbohydrate, in for example chicory and dahlia roots, artichokes. Consists of from 5 to 40 (occasionally 60) connected residues of fructose. The solubility in water and thus the availability of inulin for the organism drops as the chain length of the molecule increases.
Uses
Oligofructoside (inulin with high water solubility consisting of 5-12 fructose molecules) and so-called soluble roughage specifically support the reproduction of bifidobacteria, which are useful for intestinal function. Oligofructosides are suitable carbohydrates for special nutrition in cases of abnormal glucose tolerance or diabetes mellitus, as cellular uptake of fructose is independent of insulin. Thus up to 30 g of fructose per day can be metabolised, even in severe cases of diabetes mellitus. - Invalid dietor simply diet
Form of nutrition which is adjusted to the requirements of the individual and the treatment of his disease. It may consist in a general restriction to nutrition (diet to reduce weight, for overweight), in the reduction of certain components (e.g. low carbohydrate diet for diabetes mellitus, low salt food for kidney disease, low fat food for pancreatic disease), in a general increase in nutrition (regeneration diet) or an increase in specific components (e.g. high protein food for extreme loss of weight). - Involutional osteoporosisA term for osteoporosis in women after the end of menstruation (menopause) or in advanced age.
- ionan atom or group of atoms that carries an electric charge
- IronChemical element, symbol Fe. Iron is a silvery white non-noble heavy metal which is soluble in acids and which is a trace element. Iron is a component of haemoglobin, which is the protein which transports oxygen in blood and which is the cause of the red colour. It also occurs in myoglobin, the source of the red colour in muscles, and in some enzymes. It occurs in animal and plant foods, such as meat and meat products, cereals and vegetables (savoy, spinach, beans and peas). Iron uptake from plant foods is markedly less than that from animal foods, but can be increased by a factor of four if foods rich in vitamin C, meat or fish are eaten at the same time. The adult iron requirement is 10 mg/day; this rises to 15 mg/day for menstruating, pregnant or nursing women. The requirement also increases in some diseases. Deficiency causes tiredness, exhaustion and problems in blood formation, even including anaemia. Iron deficiency in children leads to growth problems, lowered resistance to infections and diarrhoea.
Increased iron intake, for example in chronic alcohol abuse, and frequent blood transfusions (when there is increased breakdown of red blood cells) can lead to pathological iron storage with tissue damage in the liver (cirrhosis), pancreas (diabetes mellitus) and heart muscle (heart muscle). - iron-deficiency anemiaanemia due to a prolonged negative iron balance, with characteristic laboratory changes accompanying each phase in the development of iron deficiency; the red blood cells are abnormally small (microcytic) and deficient in hemoglobin (hypochromic)
- IschaemiaReduction or interruption of the perfusion of an organ, part of an organ or tissue, as the result of inadequate blood flow, for example from thrombosis or embolism. The result is a reduction in the provision of oxygen to the affected tissue. If this persists for an extended period, necrosis can develop, which means that there are changes in the cells which lead to irreversible loss of cellular function and tissue death. Cf. infarct.
- Ischaemic heart diseasesee coronary heart disease
- ischemiccharacterised by deficient blood flow to an organ or tissue
- Islets of Langerhansalso known as the pancreatic islets
The part of the pancreas which produces hormones. There are about one million Langerhans islets and each of these is heavily perfused and innervated and contains up to 5000 large cells which form hormones. The Langerhans islets consist of four cell types. A-cells produce the hormone glucagon, B-cells the hormone insulin and D-cells the hormone somatostatin. PP-cells produce pancreatic polypeptide, which inhibits the release of pancreatic enzymes and bile flow. The B-cells make up about 60-80% of the islet cell volume, followed by the A-cells with 15-20%, the D-cells with 5-15% and the PP-cells with up to 2%.
Glossary entries: Roche and Walter de Gruyter, Berlin