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.
- Daughter TumourSee Metastasis.
- deficiency anemiaanemia due to dietary deficiency or malabsorption of factors required for blood production (erythropoiesis and hemoglobin synthesis), e.g. iron, various vitamins (vitamin A, B12, folic acid), proteins, orotic acid see also Anemia of pregnancy
- DemineralisationDeficiency of the body in minerals, caused for example by loss of phosphate and calcium with rickets, caries, vomiting and also with mineral-deficient nutrition. Cf. calcium.
- Depot fatDepot fat mostly means the triglycerides, which are stored in subcutaneous tissue and in the organs in the abdominal cavity. This helps thermal isolation and serves as a reserve of water and energy.
- DermoidA dermoid is a benign tumour which contains cells derived from embryonic cell layers and which therefore consists of different tissues. The tumour mostly has the form of a limited cavity in the tissue (cyst). This is covered with skin cells and contains a sebum-like mass mixed with hairs and a so-called Kopfhöcker (ectodermal inclusion) with teeth, cartilage, bone and neural tissue. Dermoids mostly occur in the ovaries and in the brain, testicles and skin. Malignant degeneration is possible.
- DextrinsDextrins are polysaccharides which are formed during the breakdown of starch. They are built up of different numbers of glucose molecules.
- Dextrosesee glucose
- diabetesa lifelong disease marked by high levels of sugar in the blood; it can be caused by too little insulin (a hormone produced by the pancreas to regulate blood sugar), resistance to insulin, or both
- Diabetes insipidusAbnormality in urinary excretion, characterised by a reduction in water reabsorption in the collecting ducts and the elimination of large quantities of dilute urine. The cause is a lack or lack of activity of the hormone ADH (except for dipsogenic diabetes, see below).
Symptoms
Frequent urination, increased thirst with increased fluid intake, sometimes dehydration
Forms
1. Diabetes insipidus centralis or diabetes insipidus neurohormonalis: The cause is the inadequate or lacking production or release of the hormone ADH. This form is only rarely in-born, but can be a result of, for example, meningitis or inflammation of the brain (encephalitis). Therapy: Treatment with ADH and of the underlying disease. 2. Diabetes insipidus renalis: In this condition, the ADH receptors in the kidney are insensitive to ADH. This condition is mostly in-born, but can also be the result of acute kidney failure or of the destruction of the ADH receptors. 3. Diabetes insipidus in pregnancy from increased metabolism of ADH. 4. Dipsogenic diabetes insipidus caused by an increased feeling of thirst, with increased fluid intake. - Diabetes mellitusalso known as sugar disease
Term for various diseases involving abnormalities in glucose metabolism which are characterised by a relative or absolute lack of the hormone insulin. Without treatment this lack of insulin leads to considerable increases in blood sugar and, depending on the severity, a variety of symptoms and conditions, as described below (see hyperglycaemia). Depending on the cause of the disease, diabetes mellitus is subdivided into type 1 diabetes and type 2 diabetes. Type 1 diabetes is a disease which is a consequence of the destruction of the cells in the pancreas (beta- or B-cells) which produce insulin. The disease mostly starts in children or in youth. There are disturbances in the immune system, which are usually caused by an immune reaction against the patients own body. As a result of this, antibodies are formed which destroy pancreatic tissue, resulting in a chronic and absolute deficiency in insulin. Type 2 diabetes is a chronic and progressive disease of the pancreatic islet cells which produce insulin, resulting in a permanent increase in blood sugar. The initial cause is reduced sensitivity of the target tissue, such as muscle, for insulin, the hormone which reduces blood sugar (see insulin resistance). The increased blood sugar from lack of insulin in both type 1 and type 2 diabetes is responsible for the characteristic concomitant disease and late complications of diabetes mellitus. See type 1 diabetes and type 2 diabetes. - Diabetic angiopathiesDiabetic angiopathies
Diabetic angiopathies are blood vessel diseases which are caused by type 2 diabetes or type 1 diabetes.
Forms
1. Diabetic microangiopathy affects small and terminal blood vessels and is the cause of certain eye, kidney, nerve and skin diseases retinopathia diabetica, diabetic glomerulosclerosis, polyneuropathy and diabetic gangrene). 2. Diabetic macroangiopathy affects the larger vessels and is early and active arteriosclerosis. - Diabetic comaalso known as Coma diabeticum
Hyperglycaemic coma, i.e. coma resulting from raised blood sugar concentrations in patients with type 2 diabetes or type 1 diabetes. Caused by lack of insulin, insulin resistance, hunger or infection.
Forms
1.Ketoacidotic coma with marked "overacidification" of the metabolism (ketoacidosis, which is acidosis caused by ketone bodies) and raised blood sugar concentrations. These are mostly under 1000 mg/dl or 55.5 mmol/l blood. This coma is typical of type 1 diabetes. 2. Hyperosmolar coma as a result of massive water loss with drying out of the body and blood poisoning by substances which should be excreted in the urine. Extremely high blood sugar concentrations develop, usually over 1000 mg/dl. This coma often develops without acidosis and is typical of type 2 diabetes. 3. Lactate acidotic coma, see lactate acidosis.
Therapy
Depending on the cause; treatment with insulin, sodium bicarbonate or tris buffer, additional fluid. Potassium replacement if there is potassium deficiency. - Diabetic counterregulationDiabetic counterregulation (or rebound) means the increase in blood sugar concentrations (hyperglycaemia) which is caused by hormones (glucagons, adrenalin, cortisol, STH). This is triggered by and tends to counteract the low blood sugar concentrations (hypoglycaemia) caused by insulin. Cf. type 2 diabetes, type 1 diabetes, Somogyi effect.
- Diabetic footLate complication of type 2 diabetes or type 1 diabetes as a result of damage to the blood vessels and nerves (polyneuropathy).
Symptoms
Range from painless skin defect to total death of the tissue as a result of deficiency in perfusion (see diabetic gangrene).
Prevention and Treatment
Removal of stress to the foot, orthopaedic shoes and insoles, chiropody, timely and consistent treatment of every small wound, possibly vascular surgery, amputation may be necessary. - Diabetic gangreneDeath of tissue as a result of poor perfusion. The initial form is dry gangrene of the toes, with dehydration and shrinking of the tissue from water loss. This is followed by wet gangrene. The tissue decays, takes on a bluish colour and is then liquefied by bacteria. Gangrene can be a (late) consequence of the symptoms of type 2 diabetes or type 1 diabetes, namely the frequent and severe arteriosclerotic damage to the foot arteries or diabetic microangiopathy. Cf. arteriosclerosis
- Diabetic glomerulosclerosisalso known as Kimmelstiel-Wilson glomerulosclerosis or diabetic nephropathy
Damage to the glomerular capillaries (the smallest blood vessels) in the kidney as a result of long term (mostly more than 10 years) type 2 diabetes or type 1 diabetes, particularly when blood sugar is poorly regulated. Diabetic glomerulosclerosis occurs to different degrees in about a third of diabetics, mostly together with retinopathia diabetica.
Symptoms
Initially there is increased fluid perfusion through the glomerular capillaries with increased formation of primary urine and somewhat increased urinary elimination of the protein albumin. At a later stage, there is a marked increase in urinary protein elimination, a decrease in blood protein levels and increases in blood fat concentrations. Kidney function gradually deteriorates. Diabetic glomerulosclerosis is the most frequent reason for kidney dialysis.
Prevention
Diabetic glomerulosclerosis in patients with type 1 or type 2 diabetes is prevented by exact regulation by the physician of blood sugar values. - Diabetic microangiopathyDisease caused by the narrowing of smaller and terminal arteries (stenosis). Diabetic microangiopathy is a typical late syndrome of type 2 diabetes or type 1 diabetes. The retina (diabetic retinopathy), kidneys (diabetic glomerulosclerosis) and the small peripheral blood vessels are particularly often affected and perfusion problems and necrosis may develop. The exact causes of diabetic microangiopathy remain unclear. The degree of diabetic microangiopathy is generally directly related to the duration and severity of the abnormalities in glucose and fat metabolism. Cf. oculomotor paralysis.
- Diabetic nephropathysee diabetic glomerulosclerosis
- Diabetic retinopathyDisease caused by the occlusion of small and terminal blood vessels of the fundus (background) of the eye. A late consequence of type 2 diabetes or type 1 diabetes (cf. diabetic microangiopathy).
Forms
1. Non-progressive diabetic retinopathy (also known as fundus retinopathy): This is manifested in retinal bleeding, bulging out of the terminal vessels, lipid deposits and swelling of the retina with a loss in visual acuity. Mostly occurs in type 2 diabetes, intensified by high blood pressure; Therapy: perhaps treatment of small areas with lasers. 2. Proliferative diabetic retinopathy: Additional changes in the fundus of the eye, including white patches with blurred edges (cotton wool foci). Also growth of new blood vessels and bleeding in the vitreous body in front of the retina. This is the result of low perfusion of the retina, resulting from occlusion of the blood vessels. Occurs mostly in type 1 diabetes, ca. 15 years after the start of the disease. The disease can lead to glaucoma and blindness. Therapy: Laser treatment of the whole retina, sometimes partial or total removal of the vitreous body.
Prophylaxis
Blood sugar should be controlled as well as possible. Therapy of concomitant diseases, such as high blood pressure and raised concentrations of blood fats (hyperlipidaemia). - diabetogenicLeading to diabetic metabolism. Diabetogenic substances include the hormones glucagons, STH, adrenalin and glucocorticoids (particularly cortisol) and the thiazides, which are a group of diabetic drugs.
- dialysateaqueous fluid containing electrolytes and often dextrose (a simple sugar) that is intended for the exchange of dissolved substances with the blood during dialysis
- DialysisDialysis is a procedure for cleansing the blood which uses machines to remove substances which the healthy body excretes through the kidney. Dialysis is used in acute kidney failure and in the treatment of poisoning by certain substances. It is either used as a transitional measure before kidney transplantation, or can be used as long term replacement therapy.
There is the risk of metabolic disease during long term dialysis treatment, particularly in bone, iron, carbohydrate and fat metabolism and in electrolyte, water and acid-base balance. - Dialysis osteopathyIn patients with chronic renal disease who are being permanently dialysed (blood wash). Bone changes as in renal osteopathy. It occurs particularly as a consequence of chronic renal failure and the resulting impaired activation of vitamin D in the kidney. Dialysis osteopathy is made worse by the treatment with heparin, which has to accompany dialysis, and by the accumulation of aluminium in bone tissue.
- Diastolesee cardiac cycle
- Dietor invalid 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 Type 1 and Type 2 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). - differential counta measure of the percentage of each type of white blood cell contained in a blood sample
- DifferentiationBiological relevance for example of a tumour in the sense of benign or malignant.
- diffusionthe movement of suspended or dissolved particles from an area of high concentration to an area of low concentration
- DigestionBreakdown of food components in the digestive tract into smaller chemical compounds, which are then taken up (absorbed) through the wall of the intestine into the blood or lymph. Digestion involves mechanical disintegration by the teeth, liquefaction by saliva, acidification by gastric juice, formation of fat emulsions with the bile, splitting with digestive enzymes and absorption through the mucous membrane of the small intestine (see small intestine, digestion of carbohydrates, digestion of proteins, digestion of neutral fats). Undigested residues are either subject to further bacterial breakdown in the large intestine or are eliminated unchanged in the faeces (roughage). Secreted water and food (ca. 9 l per day) are mostly absorbed into the blood in the jejunum, a section of the small intestine which is connected to the duodenum. The movements of the intestinal musculature propel the chyme through the digestive tract. Digestion is regulated both neurally and by hormones.
- Digestion of carbohydratesCarbohydrates are only absorbed in the intestine as monosaccharides. The breakdown of polysaccharides (starch, glycogen) starts with the enzyme alpha-amylase in the saliva, which is then inactivated in the acid environment in the stomach. The resulting mixture is split into disaccharides by the alpha-amylase of the (pancreas). These are then split into monosaccharides by enzymes in the brush border of the intestinal mucous membrane and aborbed into blood in this form. This absorption can be enhanced by thyroid hormones. Cf. digestion,digestion of proteins, digestion of neutral fats).
- Digestion of neutral fatsThe breakdown of neutral fats (triglycerides) after ingestion in food starts with the enzymes in gastric juice. The fats are emulsified by bile acids and phospholipids and then broken down by enzymes from the pancreas (pancreatic lipases, see lipasen). Free fatty acids and monoacylglycerols (see glycerols) diffuse passively into the cells of the intestinal mucous membrane and are reassembled there to triglycerides. They pass into the lymph in the form of chylomicrons (small lipoprotein particles) and then into venous blood. After very fatty food they can cause serum to appear turbid (hyperlipidaemia.Cf. digestion, digestion of carbohydrates, digestion of proteins.
- Digestion of proteinsIn adults predominantly free aminoacids are absorbed in the intestine. Metabolism of proteins starts in the stomach with denaturation (destruction of spatial structure) by hydrochloric acid, followed by breakdown by the enzyme pepsin. The enzymes secreted by the pancreas cause further breakdown in the small intestine . Di-, tri- and tetrapeptides are then either directly absorbed in the intestine or further split by enzymes known as peptidases. Free aminoacids are absorbed through the cells of the surface of the intestine by active transport, which means that energy is expended. Cf. digestion,digestion of carbohydrates, digestion of neutral fats.
- Digitalis glycosidesChemical compounds which are active on the heart and which are contained in 1. Digitalis lanata (woolly foxglove); 2. Digitalis purpurea (red foxglove). Use: see cardiac glycosides.
- DiphosphonatesOutdated term for bisphosphonates.
- Direct measurement of blood pressurealso known as invasive measurement of blood pressure
Measurement of blood pressure during major operations or in patients in intensive care with a catheter laid in an artery. Direct measurement of blood pressure is more exact than indirect measurement of blood pressure. Continuous measurement of blood pressure is possible. - DisaccharidesDouble sugar; carbohydrate from two monosaccharides linked by a glycosidic bond. The disaccharides are classified according to 1. The type of the monosaccharides,
2. Ring type of the molecule, 3. Position of the connected OH-groups, 4. Configuration of the glycosidic bond. Important disaccharides include saccharose, maltose and lactose (milk sugar). - Disturbance in cerebral perfusionDisturbance in the perfusion of the brain. Occurs mostly after age 50 and men are more often affected than women. The most severe complication is stroke. Cf. arterial occlusive diseases.
Causes
Particularly arteriosclerosis of the vessels which serve the brain, constriction of the vessels within or outside the brain (most frequently constriction of the internal jugular artery with the danger that an embolism is released into the brain, also embolisms from the heart, inflammatory vascular disease, abnormal blood flow properties and low arterial pressure. Risk factors include arterial hypertension (hypertension), high blood fat levels, diabetes mellitus (type 2 diabetes, type 1 diabetes) and nicotine abuse.
Diagnosis
Clinical investigation, ECG (cardiac arrythmia?), brain computer tomography (infarct?, bleeding?), ultrasound investigation of the arteries which serve the brain; perhaps further investigation with other methods, such as angiography of the arteries which serve the brain.
Therapy
1. Removal of risk factors or treatment of the underlying disease; 2. To prevent another episode of abnormal cerebral perfusion, e.g. acetylsalicylic acid. If it is suspected that an embolism has come from the heart, use coagulation inhibitors to thin the blood; 3. Operation to remove the blood clot, only if there is symptomatic constriction of the internal jugular (more than 70 %), possibly widening of the artery with the balloon catheter (PTA); 4. Possibly specific treatment for stroke. - Disturbance in vertebrobasilar perfusionDisturbance in the perfusion of the area served by the spinal artery (Arteria vertebralis) and the connected Arteria basilaris.
Causes
Arteriosclerosis, constriction or occlusion of the Arteria vertebralis, embolism, more rarely inflammation of the blood vessels.
Symptoms
Fleeting symptoms include giddiness, double vision, lack of sensitivity in the skin of the head, pain in the back of the head, confusion and symptoms arising from damage to the brain stem, such as paralysis to the muscles of the eye and face, hoarseness, drooping eyelid, constriction of the pupils. Cf. disturbance in cerebral perfusion - Disturbances in ossificationDisturbances in bone formation, which may either be in-born or acquired. In-born disturbances in ossification are due to damage before the birth, which may either be genetic or due to external factors. A condition which arises after birth is called an acquired disturbance in ossification.
Forms
I. general disturbance in ossification: 1. primary, in-born disturbance in ossification, such as disturbances in cartilage formation, which are marked at birth and which generally do not get worse; disturbances in the activity of the osteoblasts (cf. osteoblasts), which lead to osteoporosis, as a result of reduced or inferior bone generation; disturbances in the activity of the osteoclasts, which lead to reduced bone breakdown; 2. secondary general disturbances in ossification caused by diseases which may be in-born or acquired after birth, e.g. secondary osteoporosis, osteomalacia, secondary osteosclerosis.
II. local disturbances in ossification: for example, germ-free death of bone mass (aseptic bone necrosis); inflammatory bone diseases: bone marrow inflammation (osteomyelitis), tuberculosis (bone tuberculosis, arthritis tuberculosa and other), syphilis, osteodystrophia deformans; bone tumours.
- disulphide bonda strong covalent bond between two sulphur-containing groups; it is very important to the folding, structure and function of proteins; also called a disulphide bridge
- Diuretic drugsDrugs which inhibit the reuptake of certain ions, particularly sodium, in the kidney. This leads to increased elimination of sodium, chloride and bicarbonate ions and (indirectly) of water. Diuretic drugs reduce blood volume in this way and improve symptoms of congestion.
Uses
In heart failure and high blood pressure, particularly thiazides, loop diuretics and substances with the same activity. See antihypertensive drugs
Side-effects
Electrolyte imbalance, particularly deficiency in blood potassium, abnormal glucose tolerance (increased predisposition to type 2 diabetes). If the diuresis is excessive there may be haemoconcentration (thickening of the blood) or collapse as a result of loss of body water. Other side-effects raised blood potassium concentration with potassium-sparing diuretics and raised potassium concentration and enlarged male breasts with aldosterone antagonists. - Diurnal profileMeasurement and recording of the concentrations of certain substances in blood and urine over 24 hours, for example of blood sugar during control of metabolism in type 2 diabetes or type 1 diabetes.
- DNAAbbreviation for deoxyribonucleic acid
DNA is the bearer of genetic information. It is predominantly localised in the cell nucleus and in the cell nucleus predominantly in the chromosomes. DNA is composed of individual nucleotides, which are bound together to form large molecules known as polynucleotides. The nucleotides contain the sugar deoxyribose and are connected through 3', 5'-phosphodiester bonds. The most important bases are adenine and guanine (two purine bases) and cytosine and thymine (two pyrimidine bases). The sequence of these bases ("the genetic code") codes for the information of the gene product it forms, which is mostly a protein, such as a structural protein or enzyme. DNA is the genetic material in most forms of life, with the exception of the so-called RNA viruses, and bears genetic traits. It is mostly present as a double strand, which consists of two polynucleotide chains of opposite polarity and which is formed as a result of the so-called base pairing between two bases. The specific screw structure of the DNA double strand is known as the double helix. The sequence of bases in one strand strictly specifies the sequence in the opposing strand. With the help of RNA, genetic information is transported out of the cell nucleus and gene products produced. - Drug JaundiceDrug jaundice is jaundice (see Icterus) which arises from allergic or cytotoxic liver damage by drugs.
- Drug-Induced IcterusLiver damage (e.g. Acute Hepatitis) caused by drugs, leading to icterus (see Icterus).
- Dukes ClassificationClassification of colorectal carcinoma. Important factors are the depth to which the tumour has penetrated and the presence of metastases in the neighbouring lymph nodes.
Dukes A: Tumour is limited to the wall of the intestine,
Dukes B: Tumour penetrates the intestinal wall and grows into the neighbouring tissue.
Dukes C1: Metastases in 1-3 neighbouring lymph nodes.
Dukes C2: Metastases in more than 3 neighbouring lymph nodes or along larger vessels.
Dukes D: Metastases in distant lymph nodes and organs. - dyslipidemiaa condition marked by abnormal concentrations of lipids in the blood
- Dysplasiabroadly referring to abnormal anatomical structure due to abnormal growth or development of organs or cells
- dyspneaan uncomfortable sensation of difficulty breathing or shortness of breath
- dysrhythmiasabnormal heart rhythms
Glossary entries: Roche and Walter de Gruyter, Berlin