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You are here:: About Roche; > Glossary

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.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Vaccination

see protective vaccination

Vaccination Calendar

also called vaccination plan

Fixed sequence for the recommended vaccinations for babies, children and young people, with the aim of achieving resistance (immunity) to important infectious diseases. Supported in Switzerland by the Swiss Committee for Vaccination Questions (Abbreviation SKIF), in Germany by the Standing Committee on Vaccination of the Robert Koch Institute (Abbreviation STIKO) and in Austria by the Upper Health Committee (Vaccination Committee). There are special recommendations for refresher and first vaccinations for adults and for specific groups (for instance, treatment before travel or for groups at risk). Cf. protective vaccination.

Vaccination Complications

Illness from a vaccination which goes beyond the normal reaction to vaccination and which may need treatment. In rare cases permanent damage may result. Vaccination complications may be caused by the vaccination antigen itself or by the helper substances in the vaccine. For example, the oral vaccine to poliomyelitis uses a weakened vaccine material which contains live viruses which can reproduce (Sabin). This can cause vaccine poliomyelitis or contact vaccine poliomyelitis in individuals who have been in close contact with someone who has been vaccinated. It is therefore recommended only to use the Salk inactivated polio vaccine (IPV). Cf. protective vaccination.

Vaccine, polyvalent

Vaccine consisting of a mixture of different vaccination antigens of the types of a pathogen (e.g. influenza virus, poliomyelitis virus). Cf. combination vaccine, protective vaccine.

Vaccines

A substance used for inoculation, consisting either of live pathogens with reduced toxicity, inactivated pathogens, or inactivated toxins or fragments of pathogens. Cf. protective immunisation.

Varicose veins

see varicosity

Varicose veins

Irregular veins which are tube or knot shaped and meander over the surface

Cause
Weakness of the wall of the vein, increase in intravenous pressure or weakness in the valves of the vein.

Occurrence
Primary (in-born) or secondary (e.g. after thrombosis), often occurs multiply in the legs (leg varicosis).

Varicosis

Extended formation of so-called varicose veins, particularly in the legs.

Forms
1. Primary varicosis with tendency to thrombosis, particularly when blood circulation is slow, e.g. after extended bed rest. Causes: mostly constitutional, as a result of general weakness in connective tissue, which is more frequently manifested with increasing age. Predisposing factors include work in standing, overweight and pregnancy. 2. Secondary varicosis as a consequence of vein disease, which leads to occlusion or local failure of the valves in the affected veins. When there is valve failure in the deeper leg veins there is increased venous reflux through the superficial veins which are connected with the deep leg veins. This is in the opposite direction from normal circulation and is mostly due to the so-called muscle pump.

Symptoms
Mechanical obstacles to venous reflux and the resulting increase in peripheral venous pressure result in the formation of superficial and deep varicose veins, with symptoms of congestion. Combinations of primary and secondary varicosis often occur in the clinic.

vascular access

a site on the body where blood is removed and returned to the body during hemodialysis

Vasculitis

Vasculitis is inflammation of the blood vessels. The symptoms and their extent depend on the position of the affected vessels. The disease may occur, for example, in infections, including infections from HIV.

Vasoconstriction

Narrowing of the blood vessels, e.g. from an increase in the tension of the vessel muscles. Cf. high blood pressure, Bayliss effect, vasodilatation.

Vasodilatation

also known as vasodilation

Expansion of the blood vessels, which may be active, e.g. from relaxation of the vessel muscles, or passive, as a result of increased blood volume. Cf. vasoconstriction.

Veins

Blood vessels leading to the heart. In the systemic circulation veins carry oxygen-poor blood and in the minor circulation oxygen-rich blood. Cf. circulation of the blood, arteries.

ventricular fibrillation

very rapid uncoordinated fluttering of the ventricles of the heart, which results in a loss of synchronisation between heartbeat and pulse beat

Viral Hepatitis

see Hepatitis, acute.

Viral Influenza

see influenza

Virologist

Biologist who has specialised in viruses.

Virostatic Drugs

Virostatic drugs are chemical compounds for the treatment of virus infections (cf. infection).

Possible Modes of Action
1. The penetration of viral genetic material and its release are hindered; 2. The replication of the viral genetic material is hindered, e.g. by inhibition of the necessary enzymes in the virus; 3. The maturation of the virus and its release are inhibited.

Use
As a result of drug side-effects and differences between individual viruses, the use of virostatic drugs has as yet been restricted to selected groups of viruses; e.g. Herpes simplex virus, influenza virus, hepatitis viruses.

Contraindications
Pregnancy, breast feeding, kidney failure, allergies and other.

Drug Side-effects
Depending on the drug, e.g. kidney damage, damage to the system which forms new blood cells (haematopoesis), or to the nervous system. Also disturbances in the digestive tract, local reactions at the site of infusion, such as thrombosis of superficial veins and inflammation of the blood vessel wall, hypersensitivity reactions.

Virus

see viruses

Virus Classification

Viruses can be classified according to various points of view, e.g. according to the type of nucleic acid (DNA, RNA), according to size, according to structure, according to the host organism in which they cause disease, or on the basis of their adaptation to distinct tissue types or organ systems (e.g. whether they infect the nervous system, the lungs or the liver). The modern classification according to consistent rules succeeded on the basis of exact chemical, physical and genetic analyses and includes an international designation, the virus family with the ending "-idae" as a group of genera with similar structure, genus with ending "-virus", etc..

Virus Load

The virus load is the name for the concentration of virus in the blood (number of copies of the virus gene/ml blood, cf. polymerase chain reaction). In HIV infections, the virus load allows statements about the course, result of the disease and the risk of transmission of the virus from mother to child.
The first test to measure the virus load (HIV-1 RNA in blood) was approved in 1994. The USA agency for registration has at the moment only approved this test for measuring virus load, as it has enough sensitivity to document the course of HIV treatment.

Viruses

Collective name for the biological structures, which in the known cases mostly cause disease, and which have the following common characteristics: 1. The genetic information is only either DNA or RNA; 2. They do not possess the enzymes which are necessary for growth and reproduction, but require for this purpose host cells which are usually specific and which may be plant cells or certain animal or human cells, in which they often cause disease. Viruses which only attack bacteria are called bacteriophages. The modern classification of viruses is mostly based on their structure and genetic similarity and only exceptionally on clinical or epidemiological characteristics.

Structure (Morphology)
Infectious viruses (so-called virions) measure 20-300 nm in length or diameter and consist of: 1. strand of nucleic acid (DNA or RNA); 2. protein coat (core, capsid; capsid and nucleic acid together are referred to as the nucleocapsid); 3. complex virions are surrounded by a coat. Nucleocapsids mostly have simple geometrical forms. The viral coat partially originates from the host cell membrane, with glycoproteins from the virus itself protruding out of it (so-called spikes). These play an important role in the virulence of the virions and in the immunological reaction of the host.

1. Viruses are always cell parasites. The virion is first bound to certain receptor structures on the cell membrane of the host cell. 2. The virus coat either merges with the membrane of the host cell or the virus is taken up into the host cell by means of invaginations in the host cell, i.e. it is surrounded by the cell membrane and forced into the inside of the cell. The membrane is then dissolved by enzymes inside the cell. 3. Multiplication of the genetic material takes place in the host cell, using the host cell's molecular equipment. 4. The nucleic acids and polypeptides produced in the host cell are assembles to make infectious virions, which then leave the host cell. The coat of a virion is derived from the cell membrane of the host cell, after the virion has left the cell through a bud-like projection and constriction of the membrane.

Viruses, Oncogenic

Viruses which can cause neoplastic changes in cells, either in the laboratory or in living animals or humans. The oncogenic or tumorigenic properties of viruses were first demonstrated in 1911 with the chicken Rous sarcoma virus. At present 100 different viruses with oncogenic potential are known. It is not yet known exactly how this happens; it is possible that the oncogenes of the body are wrongly regulated or that foreign oncogenes are introduced. Viruses connected with the development of human tumours include the following: human papilloviruses (cervical carcinoma), hepatitis B virus (primary liver cell carcinoma; cf. hepatitis virus), retroviruses (HTLV 1, 2; human T-cell lymphoma), Epstein Barr virus (Burkitt lymphoma, nasopharyngeal carcinoma), adenoviruses; There is no definitive proof that herpes simplex virus and the cytomegalovirus are oncogenic.

Vitamin C

also called ascorbic acid

Water soluble vitamin which is readily oxidised.

Biochemical Function
Radical trap; serves as redox system is hydroxylation reactions, participates in electron transport, increases iron absorption, inhibits formation of nitrosamines and may influence the immune system.

Occurrence
Vitamin C occurs widely in foods from both plants and animals, as higher plants and most animals can produce vitamin C from glucose. There are particularly high levels of vitamin C in fruit (e.g. common sea buckthorn, blackcurrants, kiwis and citrus fruits), vegetables (parsley, paprika, kale, broccoli, potatoes) and liver. An adult requires 75 mg/day; for smokers this should be increased by 40 mg/day.

Symptoms of Deficiency
False or deficient nutrition (e.g. single older people, extreme diets, alcoholism), increased requirements (e.g. pregnancy, dialysis, smoking) or disturbances in intestinal absorption can lead to vitamin C deficiency (scurvy), with reduced physical energy, tiredness, irritability and pain in the limbs and joints. Subsequently, bleeding in the skin, mucous membrane and musculature, spongy gums, tooth loss, poor wound healing and susceptibility to infection can develop.

Diseases from overdosage with vitamin C are unknown, neither from high uptake in food nor from the therapeutic use of high doses. This is because vitamin C which is not needed is excreted in the urine.

Vitamin D

see calciferols

Vitamin D deficiency

Also called calcitriol deficiency

Inadequate formation of vitamin D3 (calcitriol) in the skin of the patient (e.g. due to inadequate time in the sun), inadequate intake in food or inadequate uptake through the intestine or other causes can lead to vitamin D deficiency. Vitamin D deficiency causes reduced uptake of calcium in the intestine and increased release of calcium from the bones (secondary hyperparathyroidism). If the calcium deficiency is marked, it can lead to rickets in children or osteomalacia in adults. Because of the possible consequences, even vitamin D deficiency without symptoms is increasingly being recognised as a reason for treatment.

Treatment
1. Treatment with vitamin D (calcitriol); caution because of the danger of an increase in blood calcium; 2. Calcium is usually given before vitamin treatment or as a supplement; 3. A combined formulation of vitamin D and calcium is given for mild vitamin D deficiency or for osteoporosis.

Other Measures
1. Possible treatment of the underlying disease; 2. Moderate solar irradiation of the skin (cf. light therapy); 3. Consumption of food which is rich in vitamin D (milk and milk products, eggs, margarine, fatty fish); 4. After treatment with vitamin D, the calcium concentration in blood serum should be regularly checked.

Vitamins

Organic compounds which are essential for the life of the organism, but which are not produced in adequate quantities or not at all in metabolism. For this reason, vitamins must be taken regularly in food. Some vitamins have specific functions, such as vitamin A in vision. Other vitamins are important for cellular metabolism. Vitamins are classified into fat and water soluble compounds. In contrast to water soluble vitamins, fat soluble vitamins can be stored, which makes an overdose (hypervitaminosis) possible. Vitamins are produced by plants and microorganisms. They come into the animal organism with food and in the intestinal bacteria in the digestive tract. In some cases, precursors of the vitamins ("provitamins") may be converted into the active form in the organism. False or inadequate nutrition in man can lead to symptoms of deficiency, which may be mild (hypovitaminosis) or severe (avitaminosis). Symptoms of deficiency may also be caused by inadequate intestinal absorption (even though the diet is adequate) or by destruction of the intestinal flora, by, for example, antibiotics. Vitamin deficiency can accompany liver damage, alcoholism (liver damage and deficient nutrition), pregnancy and breast feeding (raised requirements). Deficiency related to diet is extremely rare in countries with adequate available food. The daily requirement is very variable from individual to individual and increases in illness, stress, pregnancy and breast feeding. Vitamins are only of therapeutic use for deficiencies. Cf. vitamin C, vitamin D.

VLDL

Abbreviation for very low density lipoproteins

Lipoproteins of very low density, which are formed in the liver and which consist or 80-95 % fat and 10-15 % protein components.

Function
Transport of triglycerides in the body. After fatty acids have been split off, VLDL is transformed into IDL and LDL.

Glossary entries: Roche and Walter de Gruyter, Berlin

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