Volume 2: Science
Glossary of scientific and other terms

Words in bold refer to other words also defined in this glossary.
EAE	Experimental allergic encephalomyelitis.
Effective dose	Dose required to produce disease (for an organism), or beneficial effect (for a therapy).
Eland	A large antelope of the genus Tragelaphus, with spiral horns, native to Africa. A ruminant.
Electrophoresis	A technique usually used to separate proteins or nucleic acids on the basis of their relative electrical charges. Generally, mixtures of protein or nucleic acid are applied to a porous support matrix, such as a gel, through which an electric field is applied. Components can be identified since they migrate in the electric field at different rates.
Electron microscope	A microscope which beams electrons at and through the object of interest, instead of light beams. This type of microscope provides the greatest resolution of extremely small details. Used for magnifying viruses, bacteria, etc. Magnification may be up to × 300,000.
ELISA	Enzyme linked immunosorbent assay. A sensitive test to measure small amounts of a particular protein in solution, using specific antibodies to identify proteins. It has been applied for the detection of MBM in ruminant feed. If successfully applied, it can indicate whether there is mammalian protein in a straight or compound feed and, more specifically, the type of mammalian protein.
Endemic	An endemic disease is one present in an animal population at all times. (BVD)
Endocrine cell	Specialised animal cell that secretes a hormone into the blood; usually part of a gland, such as the thyroid or pituitary gland. (Alberts)
Enzyme	A protein that catalyses chemical reactions of other substances without itself being destroyed or altered upon completion of the reactions.
Enzyme digestion	A process in which an enzyme (itself a protein) uses water to 'degrade' or split a protein into amino acids or groups of amino acids called peptides.
Epidemic	Term used to describe a disease affecting or tending to affect a disproportionately large number of individuals within a population, community, or region at the same time.
Epidemiology	A branch of science dealing with the incidence, distribution and control of a disease in a population.
Excitotoxicity	The death of nerve cells as a result of abnormally prolonged stimulation, produced by increasing the duration and effective concentration of neurotransmitter at the cell synapse (the point at which a nervous impulse passes from one neuron to another).
Experimental allergic encephalomyelitis (EAE)	An autoimmune disease that can be induced in various animals experimentally by the injection of myelin basic protein (from homogenised brain or spinal cord) with an immunostimulatory substance.
Extraneural tissues	Tissues outside the nervous system.
Familial	Tending to occur in more members of a family than expected by chance alone.
FFI	Fatal Familial Insomnia, a rare human familial neurodegenerative disease shown to be caused by a prion gene mutation.
Fibril	A small or slender fibre (adjective: fibrillar). (COD)
Formalin	A colourless solution of formaldehyde in water used as a preservative for biological specimens, etc.
Frameshift	Relating to, being, or causing a mutation in which a number of nucleotides not divisible by three is inserted into or deleted from the genetic code, so as to change the reading frame of some triplet codons during protein synthesis.
FSE	Feline spongiform encephalopathy, first discovered in a cat in 1990.
Gamete	A sperm or egg. Also known as 'germ cell'.
Gastric	Of, or relating to the stomach.
Gastrointestinal	Of, relating to, affecting, or including both stomach and intestine.
Gelatine	Colourless, transparent, jelly-like material, derived from collagen, and obtained by boiling animal bones.
Gemsbok	An African antelope. Not a ruminant. Cf. the nyala.
Gene	That part of the DNA molecule which carries the information defining the sequence of amino acids in a specific polypeptide chain. (IPCS)
Gene locus	The position in a chromosome of a particular gene.
Genetic code	The sequence of bases in nucleic acid which determines the order of amino acids in the polypeptide synthesised from it.
Genome	The complete set of genetic material of an organism. (COD)
Genotype	The genetic constitution of an individual organism. (COD)
Germ line mutation	A mutation present in gametes which will transmit to the next generation.
Glycoform pattern	The distinctive pattern produced following electrophoresis of protease-digested prion protein.
Glycoprotein	A protein which has carbohydrate groups attached to the polypeptide chain.
Glycosylation	The process by which proteins are modified by the addition of sugars (carbohydrates).
Gonadotrophin	Hormone secreted by the pituitary gland, which controls the activities of the testes and ovaries. Human pituitary-derived gonadotrophin was once used as an infertility treatment for women. Some women following this treatment developed CJD from infected pituitaries.
Greaves	A product of the rendering process, after the extraction of tallow, which is further processed into meat and bone meal.
Grey matter	Those parts of the brain and spinal cord that contain tightly packed nuclei of nerve cells, and are darker in colour than white matter which is largely made up of the axons of nerve cells.
GSS	Gerstmann-Sträussler-Scheinker syndrome, a rare familial spongiform encephalopathy, now known to be associated with mutations in the PrP gene. Also known as Gerstmann-Sträussler Syndrome.
Haploid	Descriptive of cells (sperm or egg) with a single set of unpaired chromosomes.
HD	Huntington's disease.
Heparin	A naturally produced anticoagulant that is found especially in liver, and is often used medically.
Heptane	Any of several organic compounds C7H16, used especially as a solvent.
Heteromeric	Describing a molecular complex composed of two or more dissimilar subunits.
Heterozygous	Having two different alleles of the same gene. Noun: heterozygote.
hGH	Human growth hormone. At one time made from post-mortem pituitaries, inadvertently contaminated with the CJD agent, and now known to have transmitted CJD to a small number of those treated with hGH for short stature.
Histology	The study of cells and tissues at the microscopic level. Adjective: histological.
Histopathology	The branch of medicine concerned with the changes in tissues caused by disease. (COD)
Holding	Land and buildings held by a freehold or leasehold occupier. (DOA)
Homogenate	The material obtained when something is homogenised.
Homogenised	Blended to make smooth, with an even distribution of particles.
Homologue	In genetics, one member of a related pair of chromosomes. Adjective: homologous.
Homomeric	Describing a molecular complex composed of identical subunits.
Homozygous	In genetics, having two identical alleles of the same gene. Corresponding positions of a pair of chromosomes. Noun: homozygote.
Hormone	Signalling molecules, excreted by specialised cells, which circulate in the blood stream and have a point of action remote from the point of excretion. Hormones generally have a stimulatory effect on a cellular activity.
Humoral	Relating to or being the part of immunity or the immune response that involves antibodies secreted by certain white blood cells and circulating in bodily fluids.
Huntington's disease (HD)	Hereditary disease characterised by involuntary movements and dementia.
Hyperbaric	Of, relating to, or utilising greater than normal pressure.
Hypochlorite	A salt of hypochlorous acid, often used as a disinfectant.
IAH	Institute for Animal Health. (Formerly the Institute for Animal Disease Research).
Iatrogenesis	Any adverse mental or physical condition induced in a patient through the effects of treatment by a physician or surgeon (adjective: iatrogenic). (Taber)
i.c.	Intracerebral.
ID50	The unit of infective dose.
Ileum	The last portion of the small intestine.
Immune response	The reaction of the body to substances that are foreign or treated as foreign. It may take various forms, eg, antibody production, cell-mediated immunity, immunological tolerance, or hypersensitivity (allergy). (IPCS)
Immune system	The body system, made up of many organs and cells, that protects the body against infection, disease and foreign substances.
Immunoblot	A method for detecting small amounts of biological materials including disease-associated form of PrP. It can therefore be used to diagnose TSEs: the materials are separated in an electric field, and transferred to a sheet on which they can be stained. See also western blot. The method requires tissue which is frozen and then homogenised, and cannot be used on material which has been fixed in formalin. In the past most tissue samples were fixed in formalin for pathological diagnosis.
Immunodeficiency	Impaired immunity resulting from inherited or acquired abnormalities of the immune system, leading to increased vulnerability to infection.
Immunofluorescence	The labelling of antibodies or antigens with fluorescent dyes especially for the purpose of demonstrating the presence of a particular antigen or antibody in a tissue preparation.
Immunomodulatory compound	A substance that affects the functioning of the immune system.
Immunosuppression	The suppression (usually by drugs) of natural immune responses.
Incidence	A measure of the frequency of disease. Incidence refers specifically to the number of new cases of a disease during a particular period of time.
Incubation	Period between infection and clinical manifestation of disease.
Index case	The first case of disease in a defined population.
Indirect immunofluorescence	A more sensitive technique than (direct) immunofluorescence. Antigens or antibodies in a tissue preparation are bound by an unlabelled primary antibody which itself is recognised by many molecules of a secondary antibody. The secondary antibody is labelled with fluorescent dye to enable detection. In effect, this results in amplification of the signal that would have been obtained if the antigen of interest had been detected directly.
Infectious	Capable of being transmitted.
Infective dose (ID50)	The amount of infectious material required to cause disease in approximately 50 per cent of inoculated animals.
Inoculation	Introduction of a pathogen (virus, bacteria, etc) into an animal.
Inoculum	Substance that is introduced into an animal to infect it with disease or to vaccinate it.
Insulin	A protein pancreatic hormone that is essential especially for the metabolism of carbohydrates and is used in the treatment and control of diabetes mellitus.
Intracerebral (i.c.)	Route of inoculation directly into the brain.
Intramuscular	Into the muscle.
Intraocular	Into the eye.
Intraperitoneal (i.p.)	Into the abdominal cavity.
Intraspinal	Into the spinal cord.
In utero	In the uterus (womb).
In vitro	In the glass (test tube), ie, observations outside the body. Cf. in vivo.
In vivo	Observations inside the living body. Cf. in vitro.
Ion	An atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons.
Ionising radiation	Can be either short-wave electromagnetic radiation such as X-rays or ultraviolet light, or radiation emitted from radioactive materials. This type of radiation can cause extensive damage to biological molecules, such as DNA.
Isoforms	Different forms of a protein that may be produced as a result of some chemical process.
Isolate	The term used to denote a pathogen or mixture of pathogens derived from a particular source. See also TSE isolate.
Kudu	A large, grey-brown African antelope (Tragelaphus strepsiceros) with large, annulated, spirally twisted horns. A ruminant.
Kuru	A human transmissible spongiform encephalopathy, found in the Fore people in Papua New Guinea. New cases are now extremely rare, after being at a high frequency just a few decades ago.
Lateral transmission	Transmission within a population other than by genetic or maternal transmission. Cf. vertical transmission.
LD50	The unit of lethal dose.
Lemur	Nocturnal mammal related to monkeys but usually regarded as constituting a distinct superfamily (Lemuroidea).
Lesion profile	The pattern of brain tissue damage, used as a distinguishing feature for different TSEs.
Lethal dose (LD50)	The amount of infectious material required to cause death in approximately 50 per cent of inoculated animals.
Lipid	An organic compound which is insoluble in water, but soluble in fat solvents such as alcohol and ether. (BMD)
Louping-ill disease	Virus disease of sheep involving brain inflammation, transmitted by the tick Ixodes ricinus. Has also been found in cattle, horses, dogs and pigs.
LRS	Lymphoreticular system. The tissues and organs (including the bone marrow, tonsils, spleen, thymus and lymph nodes) which produce and store cells that fight infection, and the network of vessels that carry lymph. Many species including ruminants have an additional primary lymphoid tissue in the gut: the ileal Peyer's patch.
Lymph	The fluid which circulates the body in the lymphatic vessels - like blood but colourless. Carries certain white blood cells.
Lymphocyte	White blood cell that produces an immune response when activated by a foreign molecule (an antigen). T-lymphocytes develop in the thymus and are responsible for cell-mediated immunity (ie, attacking and destroying antigens directly), and for stimulating certain white blood cells. B-lymphocytes develop in the bone marrow in mammals and are responsible for the production of circulating antibodies.
Lymphoid tissue	Tissue involved in the production of lymph, lymphocytes and antibodies - consists of the lymph nodes, thymus, tonsils and spleen.
Macaque	Group of Old World monkeys from Africa and Asia.
MAFF	Ministry of Agriculture, Fisheries and Food.
Marmoset	A small tropical American monkey.
Maternal transmission	Transmission from dam to offspring in utero or in the immediate post-partum period.
MBM	Meat and bone meal. Animal-derived protein produced by rendering. Used as a protein source in animal feed.
Medulla oblongata	The hindmost part of the brain, which is continued into the spinal cord. In it are situated several of the nerve-centres which are most essential to life, such as those governing breathing, the action of the heart and swallowing. (BMD)
Meiosis	A type of cell division that results in daughter cells each with half the number of chromosomes of the parent cell. (COD)
Membrane protein	Protein that is embedded in the surface membranes of cells and cellular organelles such as the nucleus.
Mesenteric	Relating to the fold of the peritoneum which supports the small intestine.
Metabolite	A product of metabolism: the chemical processes that occur within a living organism to maintain life.
Methionine	An essential amino acid and of relevance to CJD, since codon 129 of the PRNP gene can code for either methionine or valine. Variant CJD cases have all been homozygous for methionine atcodon 129, whilst iatrogenic cases are associated with a significant excess of the valine homozygous genotype.
Methyl bromide	Chemical mutagen which leaked from a factory in Smarden (Kent) in 1963.
Micro-organism	An organism of microscopic or ultramicroscopic size, including bacteria and viruses.
Missense	A mutation that produces an abnormal form of protein which is normally produced.
Mitosis	A type of cell division that results in daughter cells each with the same number and kind of chromosomes as the parent cell. Cf. meiosis.
Molecular chaperone	Proteins which mediate the correct assembly of other polypeptides, but are not themselves part of the functional assembled structure.
Molecular mimicry	Describes bacteria that share molecular sequences with particular human tissues.
Molecular weight	The average mass of a molecule of a compound compared to 1/12 the mass of carbon-12 and calculated as the sum of the atomic weights of the constituent atoms.
Morbid	Affected with or induced by disease.
Moufflon	Wild sheep.
MRC	Medical Research Council.
MRI	Magnetic resonance imaging. An imaging technique used to image internal structures of the body, particularly the soft tissues, eg, the brain.
mRNA	Messenger RNA.
Multimeric protein structure	The structure of a protein comprised of more than one subunit.
Multiple sclerosis	A disease of the brain and spinal cord which produces symptoms such as paralysis and tremors.
Mutation	A change occurring in the genetic material (DNA) in the chromosomes of a cell. It can be caused by a fault in the replication of a cell's genetic material when it divides to form two daughter cells. It can also occur as a result of exposure to radiation or chemical mutagens.
Mutism	Inability to speak, especially as the result of brain damage.
Myelin	The 'insulation' on some neurons.