Hepatitis C
Glossary
alopecia loss of hair occurring at any site and from any cause.
ALT alanine aminotransferase, an enzyme that interconverts L-alanine and D-alanine. It is a highly sensitive indicator of hepatocellular damage. When such damage occurs, ALT is released from the liver cells into the bloodstream, resulting in abnormally high serum levels. Normal ALT levels range in man from 10 to 32 U/l; in women, from 9 to 24 U/l. The normal range for infants is twice that of adults.
amino acids the basic units of proteins, each amino acid has a NH-C(R)-COOH structure, with a variable R group. There are altogether 20 types of naturally occurring amino acids.
antibody a protein molecule formed by the immune system which reacts specifically with the antigen that induced its synthesis. All antibodies are immune globulins.
antigen any substance which can elicit in a vertebrate host the formation of specific antibodies or the generation of a specific population of lymphocytes reactive with the substance. Antigens are protein or carbohydrate, lipid or nucleic acid, or contain elements of all or any of these as well as organic or inorganic chemical groups attached to protein or other macromolecule. Whether a material is an antigen in a particular host depends on whether the material is foreign to the host and also on the genetic makeup of the host, as well as on the dose and physical state of the antigen.
arthralgia joint pain with objective findings of heat, redness, tenderness to touch, loss of motion, or swelling.
AST aspartate aminotransferase the enzyme that catalyzes the reaction of aspartate with 2-oxoglutarate to give glutamate and oxaloacetate. Its concentration in blood may be raised in liver and heart diseases that are associated with damage to those tissues. Normal AST levels range from 8 to 20 U/l. AST levels fluctuate in response to the extent of cellular necrosis.
bilirubin is the chief pigment of bile, formed mainly from the breakdown of hemoglobin. After formation it is transported in the plasma to the liver to be then excreted in the bile. Elevation of bile in the blood (>30 mg/l) causes jaundice.
carcinoma a malignant epithelial tumor. This is the most frequent form of cancer.
carrier is a person who has HCV (HBV, HDV) in his or her blood even if all symptoms have disappeared. Because the virus is present in the blood, it can be transmitted to others. The HBV carrier can be recognized by a specific blood test.
cirrhosis a chronic disease of the liver characterized by nodular regeneration of hepatocytes and diffuse fibrosis. It is caused by parenchymal necrosis followed by nodular proliferation of the surviving hepatocytes. The regenerating nodules and accompanying fibrosis interfere with blood flow through the liver and result in portal hypertension, hepatic insufficiency, jaundice and ascites. Cirrhosis is a more severe, irreversible process of liver inflammation, necrosis, and regeneration. In hepatitis C, cirrhosis occurs as a late stage sequela of chronic infection, and may take 20-30 years to develop.
codon the smallest unit of genetic material that can specify an amino acid residue in the synthesis of a polypeptide chain. The codon consists of three adjacent nucleotides.
cytopathic that kills the cells. EIA enzyme immunoassay
ELISA enzyme-linked immunoassorbent assay
endemic continuously prevalent in some degree in a community or region.
endoplasmic reticulum a network or system of folded membranes and interconnecting tubules distributed within the cytoplasm of eukaryotic cells. The membranes form enclosed or semienclosed spaces. The endoplasmic reticulum functions in storage and transport, and as a point of attachment of ribosomes during protein synthesis.
enzyme any protein catalyst, i.e. substance which accelerates chemical reactions without itself being used up in the process. Many enzymes are specific to the substance on which they can act, called substrate. Enzymes are present in all living matters and are involved in all the metabolic processes upon which life depends.
epidemic an outbreak of disease such that for a limited period a significantly greater number of persons in a community or region suffer from it than is normally the case. Thus an epidemic is a temporary increase in incidence. Its extent and duration are determined by the interaction of such variables as the nature and infectivity of the casual agent, its mode of transmission and the degree of preexisting and newly acquired immunity.
epitope also known as antigenic determinant. A localized region on the surface of an antigen which antibody molecules can identify and bind.
follicle a small, saclike depression.1
genome the total genetic information present .
genotype the genetic constitution of an individual.
histopathology the study of the structural alterations of cells and tissues caused by disease.1
humoral pertaining to the humors, or certain fluids, of the body.
idiopathic pulmonary fibrosis chronic inflammation and progressive fibrosis of the pulmonary alveolar walls, with steadily progressive dyspnea, resulting finally in death from oxygen lack or right heart failure.6
IgG antibodies IgG is the most abundant of the circulating antibodies. It readily crosses the walls of blood vessels and enters tissue fluids. IgG also crosses the placenta and confers passive immunity from the mother to the fetus. IgG protects against bacteria, viruses, and toxins circulating in the blood and lymph.
IgM antibodies IgMs are the first circulating antibodies to appear in response to an antigen. However, their concentration in the blood declines rapidly. This is diagnostically useful, because the presence of IgM usually indicates a current infection by the pathogen causing its formation. IgM consists of five Y-shaped monomers arranged in a pentamer structure. The numerous antigen-binding sites make it very effective in agglutinating antigens. IgM is too large to cross the placenta and hence does not confer maternal immunity.
incidence the number of cases of a disease, abnormality, accident, etc., arising in a defined population during a stated period, expressed as x cases per 1000 persons per year.
interferon a protein produced in organisms infected by viruses, and effective at protecting those organisms from other virus infections. Interferons exert virus-nonspecific but host-specific anti viral activity by inducing the transcription of cellular genes coding for anti viral proteins that selectively inhibit the synthesis of viral DNA and proteins. Interferons also have immunoregulatory functions. Production of interferon can be stimulated by viral infection, especially by the presence of double stranded RNA, by intracellular parasites, by protozoa, and by bacteria and bacterial products. Interferons have been divided into three distinct types (a, ß, and ?) associated with specific producer cells and functions, but all animal cells are capable of producing interferons, and certain producer cells (leukocytes and fibroblasts) produce more than one type (both a and ß). Combination of pegylated a-interferon with ribavirin is the therapy of choice for treatment of chronic hepatitis C.
immune globulin (IG) is a sterile preparation of concentrated antibodies (immune globulins) recovered from pooled human plasma processed by cold ethanol fractionation. Only plasma that has tested negative for a) hepatitis B surface antigen (HBsAg), b) antibody to human immunodeficiency virus (HIV), and c) antibody to hepatitis C virus (HCV) is used to manufacture IG. IG is administered to protect against certain diseases through passive transfer of antibody. The immune globulins are broadly classified into five types on the basis of physical, antigenic and functional variations, labeled respectively IgM, IgG, IgA, IgE and IgD.
immune system our body’s natural defense system, involving antibodies and a class of white blood cells called lymphocytes.
jaundice is a yellow discoloration of the skin and mucous membranes due to excess of bilirubin in the blood, also known as icterus.
leukopenia an abnormal decrease in the number of leukocytes in the blood.
lumen the cavity or channel between a tube or tubular structure.
lymphocyte a leukocyte of blood, bone marrow and lymphatic tissue. Lymphocytes play a major role in both cellular and humoral immunity, and thus several different functional and morphologic types must be recognized, i.e. the small, large, B-, and T-lymphocytes, with further morphologic distinction being made among the B-lymphocytes.
membranoproliferative glomerulonephritis chronic glomerulonephritis characterized by mesangial cell proliferation and irregular thickening of the glomerular capillary wall.6
microsome any of the vesicular fragments of endoplasmic reticulum formed after disruption of and centrifugation of cells.6
microvesicular steatosis fatty change in which numerous small lipid droplets are present in the cytoplasm.6
myalgia pain in the muscles.
necrotizing vasculitis any of a group of disorders characterized by inflammation and necrosis of blood vessels, occurring in a broad spectrum of cutaneous and systemic disorders.6
nucleotide a molecule formed from the combination of one nitrogenous base (purine or pyrimidine), a sugar (ribose or deoxyribose) and a phosphate group. It is a hydrolysis product of nucleic acid.
nucleus a membrane-bounded compartment in an eukaryotic cell which contains the genetic material and the nucleoli. The nucleus represents the control center of the cell. Nuclei divide by mitosis or meiosis. plasma the liquid matrix in which the blood cells and blood proteins are suspended in. It contains an extensive variety of solutes dissolved in water. Water accounts for about 90% of blood plasma.
polymerase an enzyme which catalyzes the replication of DNA (DNA polymerase) or RNA (RNA polymerase).
porphyria cutanea tarda familial or sporadic porphyria, characterized by liver dysfunction and photosensitive cutaneous lesions, with hyperpigmentation and scleroderma-like changes in the skin, and increased excretion of uroporphyrin; caused by a deficiency of uroporphyrinogen decarboxylase induced in sporadic cases by chronic alcoholism; autosomal dominant inheritance in familiar cases.2
polyarteritis nodosa a generalized arteritis characterized by necrosis of medium-sized and small arteries and involving many organs including the heart, gastrointestinal tract, muscles, and kidneys. It is one of the connective tissue disorders.1
prevalence is the number of instances of infections or of persons ill, or of any other event such as accidents, in a specified population, without any distinction between new and old cases.
prophylaxis is the prevention of disease, or the preventive treatment of a recurrent disorder.
protein large molecule made up of many amino acids chemically linked together by amide linkages. Biologically important as enzymes, structural protein and connective tissue.
reverse transcriptase an enzyme that catalyzes the formation of DNA using an RNA template, and is thus an RNA-dependent DNA polymerase. The name refers to the fact that the enzyme transcribes nucleic acids in the reverse order from the usual DNA-to-RNA transcription. RIBA™ recombinant immunoblot assay
rigors stiffness, inflexibility.
RT-PCR reverse transcriptase - polymerase chain reaction. A technique commonly employed in molecular genetics through which it is possible to produce copies of DNA sequences rapidly. Qualitative RT-PCR for HCV test to detect HCV RNA by amplification of viral genetic sequences. Quantitative assays for HCV RNA tests to detect HCV RNA concentration (viral load) by amplification of viral genetic sequences or by signal amplification.
seroconversion the production in a host of specific antibodies as a result of infection or immunization. The antibodies can be detected in the host’s blood serum following, but not preceding, infection or immunization.
serotype a subgroup within a species, defined by reaction of one or more antigens with the corresponding anti serum.1
serum is the clear, slightly yellow fluid which separates from blood when it clots. Sera containing antibodies and antitoxins against infections and toxins of various kinds (antisera) have been used extensively in prevention or treatment of various diseases.
sialadenitis inflammation of a salivary gland or glands.1
Sjögren’s syndrome a symptom complex of unknown etiology, usually occurring in middle-aged or older women, marked by the triad of keratoconjunctivitis sicca with or without lacrimal gland enlargement, xerostomia with or without salivary gland enlargement, and the presence of connective tissue disease, usually rheumatoid arthritis but sometimes systemic lupus erythematosus, scleroderma, or polymyositis. An abnormal immune response has been implicated.6
thrombocytopenia a fewer than normal number of platelets per unit volume of blood, i.e. fewer than 130 x 109 platelets per liter. titre a measure of the concentration or activity of an active substance.
transcription the process by which a strand of RNA is synthesized with its sequence specified by a complementary strand of DNA, which acts as a template. The enzymes involved are called DNA-dependent RNA polymerases.
translation the process of forming a specific protein having its amino acid sequence determined by the codons of messenger RNA. Ribosomes and transfer RNA are necessary for translation.
tumor a lump due to uncontrolled cell division, may be benign or malignant. Malignant tumors cause cancer. Tumors are able to spread to other parts of the body (metastasize) and begin secondary growths at these other sites.
vaccine an antigenic preparation used to produce active immunity to a disease to prevent or ameliorate the effects of infection with the natural or “wild” organism. Vaccines may be living, attenuated strains of viruses or bacteria which give rise to inapparent to trivial infections. Vaccines may also be killed or inactivated organisms or purified products derived from them. Formalin-inactivated toxins are used as vaccines against diphtheria and tetanus. Synthetically or genetically engineered antigens are currently being developed for use as vaccines. Some vaccines are effective by mouth, but most have to be given parenterally.
viremia the presence of viruses in the blood, usually characterized by malaise, fever, and aching of the back and extremities.6
virion a structurally complete virus, a viral particle.1
virus any of a number of small, obligatory intracellular parasites with a single type of nucleic acid, either DNA or RNA. The nucleic acid is enclosed in a structure called a capsid, which is composed of repeating protein subunits called capsomeres, with or without a lipid envelope. The complete infectious virus particle, called a virion, must rely on the metabolism of the cell it infects. Viruses are morphologically heterogeneous, occurring as spherical, filamentous, polyhedral, or pleomorphic particles. They are classified by the host infected, the type of nucleic acid, the symmetry of the capsid, and the presence or absence of an envelope.