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Glossary

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A

Acute
having a short and relatively severe course.
Adductor
muscles which move a portion of the body toward the midline.
Aetiology
cause of a disease.
Agonists
a drug that stimulates physiologic activity at cell receptors, thus triggering a biochemical response.
Alleles
any one of a series of two or more different genes that occupy the same position (locus) on a chromosome.
Amino acid
any acid containing an amino group, which consists of nitrogen combined with hydrogen. The alpha-amino acids are the building blocks of all proteins.
Anatomical
concerning body structure.
Antagonists
a substance that tends to nullify the action of another, as a drug that binds to a cell receptor without eliciting a biological response.
Antibiotic
a chemical substance produced by a microorganism, which has the capacity to inhibit the growth of or kill other microorganisms.
Antibody
a Y-shaped protein secreted by immune cells; also known as an immunoglobulin. Each antibody is specific for a particular antigen (substance that can elicit an immune response) and can counteract the effect of the antigen.
Anticholinergic
an agent that blocks parasympathetic nerves.
Antigen
a molecule which induces the formation of an antibody.
Aphasia
a defect or loss of the ability to speak or write and loss of the ability to understand spoken or written language, due to injury or disease of the brain centres.
Asymptomatic
showing or causing no symptoms.
Ataxic
having poor co-ordination of movements.
Atom
the smallest unit of an element, consisting of a positively charged nucleus containing protons and neutrons, surrounded by a cloud of electrons. An atom is so small that a single drop of water contains more than a million million billion atoms.
Atrophy
a wasting away or diminution in the size of a cell, tissue, or organ.
Autoimmune
a condition in which an individual's immune system starts reacting against his or her own tissues.
Autonomic nervous system (ANS)
neurons (nerve cells) that are not under conscious control. The CNS comprises two opposing components the sympathetic and parasympathetic nervous systems. The sympathetic nervous system accelerates the heart rate, constricts blood vessels, and raises blood pressure. The parasympathetic nervous system slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles.
Axon
the long, thread-like part of the nerve cell that extends from the cell body. The axon is specialized for signal transduction. At the end of the axon, the nerve impulses are transmitted to other neurones or to effector organs.

B

B-cells
a type of lymphocyte normally involved in the production of antibodies to combat infection. It is a precursor to a plasma cell. During infections, individual B-cell clones multiply and are transformed into plasma cells, which produce large amounts of antibodies against a particular antigen on a foreign microbe. This transformation occurs through interaction with the appropriate T-helper cells.
Barbiturates
a class of chemicals used as sedatives, hypnotics, anaesthetics and anticonvulsants.
Base
an alkaline molecule that can combine with an acidic molecule. Adenine, thymine, guanine and cytosine are nitrogenous bases, meaning that they contain nitrogen atoms.
Benign MS
characterised by two or more attacks with remissions followed by complete recovery and little or no accumulation of disability. The attacks can be years apart, making diagnosis difficult. About 25% of all people with MS have benign MS. Some people with benign MS may eventually enter a progressive phase. Benign MS is one of four types of MS (primary progressive, relapsing-remitting, secondary progressive).
Benzodiazepines
a type of drug to treat anxiety, among other things.
Beta-blockers
a large group of medications that act to block specific receptors in the nervous system. Their effects include slowing of the heart rate, reduction in blood pressure, and reduced anxiety.
Beta interferon
a natural substance that plays an important role in the immune system, which can be produced using the techniques of recombinant technology.
Bioavailability
availability of medication to the body in a form that the cells can use.
Biological activity
the ability of a molecule to bring about a specific biological change.
Blinding
in the case of testing the reliability and validity of EDSS, the clinician is not given access to past test results in order to ensure their current assessment is objective during the trial.
Bolus
a given amount of a drug.
Brainstem
the stalk-like part of the brain connecting the spinal cord and the forebrain. The brainstem functions as an important relay station; every nerve impulse that passes between the brain and the spinal cord must pass through the brainstem to allow the body to function normally.

C

Carbohydrate
a string of sugar (monosaccharide) units joined in a chain to form a polysaccharide.
Cardiac arrhythmias
a disturbance in the electrical activity of the heart that manifests as an abnormality in heart rate or rhythm.
Central nervous system (CNS)
the brain and spinal cord together make up the CNS.
Centrifugation
spinning cells or other matter at great speeds to generate a centrifugal force, which separates particles or fluids according to their weight or density. The process speeds up the normal effect of gravity.
Cerebral cortex
the outer layer of grey matter of the brain, approximately 2 mm thick, covering the entire surface of the cerebral hemispheres. The cerebral cortex is made up of neurones (nerve cells) and supporting cells (glial cells) and functions to correlate information from many sources to maintain cognitive function (all aspects of perceiving, thinking and remembering).
Cerebrospinal fluid (CSF)
fluid in the spinal cavity and brain that protects and provides nutrition to CNS tissue.
Chemical precipitation
depositing (or settling out) a protein that was previously in solution by changing the chemical composition of the solution.
Chromatography
separating dissolved substances, such as proteins, DNA or RNA, by the distance they travel across a surface according to size or electrical charge. Separating the different colours in black ink using blotting paper is a simple form of chromatography, from which it originally took its name (from the Greek khroma, or colour).
Chronic
persisting over a long period of time.
Chronic progressive
general term used to describe both primary and secondary progressive multiple sclerosis.
Clone
to make an identical copy.
Clonus
a form of movement marked by contractions and relaxtions of a muscle, occurring in rapid succession.
Codon
a triplet of bases in DNA, which form the code for a single amino acid.
Cognitive function
the mental processes, which include perception, reasoning, acts of creativity, problem-solving and possibly intuition.
Contractures
a condition of fixed high resistance to passive stretch of a muscle,
Contralateral
occurring on or acting in conjunction with the opposite side of the body, for example, when there is a sensation of pain or paralysis on the side opposite to that bearing the lesion.
Control
a group of participants used as a standard of comparison in an experiment. They should have the same characteristics as the group receiving the study drug. This can be achieved by randomisation.
Convergence
the turning inward of the lines of sight toward each other.
Corticosteroids
any of the steroids produced by the adrenal cortex. They are divided, according to their predominant biological activity, into three major groups glucocorticoids (e.g. cortisol, cortisone), chiefly influencing carbohydrate, fat and protein metabolism, mineralocorticoids (for example aldosterone), affecting the regulation of electrolyte and water balance. The corticosteroids can be used clinically to suppress the immune response.
Culture
a growth of micro-organisms or other living cells.
Cytokine
signalling molecules that mediate interactions between cells. Examples include interferons (IFNs), tumour necrosis factors (TFNs), interleukins (ILs) and transforming growth factors (TGFs).
Cytoplasm
the contents of a cell, excluding the nucleus.

D

Deoxyribonucleic acid (DNA)
DNA is found in the cell nucleus and is responsible for encoding the genetic information in genes. It is composed of two strands of nucleic acid wound into a double helix. DNA takes its name from the sugar component deoxyribose.
Demyelination
destruction, removal or loss of the myelin sheath of a nerve or nerves.
Depot
a drug prepared as an oily solution to ensure slow release after injection.
Differential diagnosis
the recognition of a particular condition or disease from others that resemble it in certain respects. It is often done by a "process of elimination".
Disability
any restriction or lack of ability, resulting from an impairment, to perform an activity in the manner or within the range considered typical for humans.
Distribution
in medicine, delivery of the medication around the body via either the blood stream or the lymph.
Dizygotic
twins which are the result of two separate zygotes, or two separate eggs fertilised by two separate sperm. They can be any combination of sexes (two males, two females, one of each).
DNA ligase
a bacterial enzyme that glues (splices) fragments of DNA end-to-end in a long chain.
Dysarthria
imperfect articulation of speech due to disturbances of muscular control which result from damage to the central or peripheral nervous system.

E

E. coli
a tribe of bacteria, some of which are indigenous to the human digestive tract and are beneficial to its normal function.
Electroencephalogram
a diagnostic test which measures the electrical activity of the brain.
Electrophoresis
a technique used to separate molecules or proteins in a solution. Since molecules have a positive or negative charge, by applying an electric field to a solution, he proteins or molecules will move at a rate that depends on its charge, shape and size.
Endoplasmic reticulum
series of convoluted membranes close to the nucleus, which are responsible for packaging proteins with carbohydrates in a process known as glycosylation.
End-point
a point marking completion of a process where an effect can be measured or observed. For clinical trials, this is the point at which an effect on the disease by the study treatment can be measured.
Enzyme
a protein that speeds up a particular biological reaction by many orders of magnitude (an organic catalyst). Most enzymes also have a prosthetic group containing a reactive mineral, such as iron, zinc or copper.
Evoked potentials
the use of electrodes to measure the electrical activity of nerves.
Excitation-contraction coupling
name given to the chain of processes linking excitation of a muscle by the arrival of a nervous impulse to the contraction of the muscle fibres.
Excretion
clearance of substances from the body, either in urine, faeces or other methods.
Experimental allergic encephalomyelitis
an autoimmune disease that can be induced in various experimental animals. Sometimes used as a model for demyelinating diseases, although whether this is entirely justifiable is not clear.
Extensor
a muscle which serves to extend or straighten any part of the body.

F

Facial palsy
a condition that involves the facial nerve and results in the paralysis of one side of the face.
Factor VIII
a blood factor involved in blood clotting. A deficiency in factor VIII leads to the clotting disorder haemophilia. This can be overcome using recombinant factor VIII.
Fermentation
the growth of cells in a nutrient soup on an industrial scale.
Fibroblast
a cell found in the connective tissue. These cells form the fibrous tissues, such as tendons, which support and bind all sorts of tissues.
Flexor
a muscle which bends or flexes any part of the body.
Forebrain
the anterior and largest portion of the brain; includes the cerebral hemispheres, the limbic system, the thalamus, diencephalon and hypothalamus, and the corpus callosum. Collectively the forebrain functions to control cognitive, sensory and motor function, and regulate temperature, reproductive functions, eating, sleeping and the display of emotions.
Formulation
preparation of a drug into a form in which it can be given therapeutically.
Fibroblast
a cell found in the connective tissue. These cells form the fibrous tissues, such as tendons, which support and bind all sorts of tissues.
Functional systems
functions of the brain, defined separately for the purposes of the EDSS scale.

G

Gait
pattern of walking.
Gene
the hereditary material, consisting of DNA. Genes code for proteins.
Genome
the total set of genes carried by an individual or cell.
Germline
the sequence of cells in the line of direct descent from zygote to gamete.
Genetic engineering
recombining or otherwise modifying genes using the techniques of biotechnology.
Glial
specialized cell that surrounds neurones providing mechanical and physical support and electrical insulation between neurones.
Glial fibres
part of the glial cell. Glial cells help nerve cells in the brain and spinal cord but do not transmit nerve impulses.
Glycosylation
the process in which carbohydrate chains are attached to a protein to form a conjugate.
Grey matter
part of the cerebral hemispheres enriched in nerve cell bodies and blood vessels.
Growth hormone
a hormone responsible for stimulating normal growth. A deficiency leads to growth defects such as dwarfism, which can be overcome by injecting recombinant growth hormone.

H

Haplotype
a set of alleles of a group of closely linked genes, which is usually inherited as a single unit.
Harvesting
collecting proteins produced by cells grown in culture.
Herniation
bulging of tissue through an opening in a membrane, muscle or bone.
Heterogeneity
the condition or state of being different in kind or nature.
Hindbrain
the area of the brain comprising the pons, medulla and cerebellum. The hindbrain functions collectively to co-ordinate motor activity, posture, equilibrium and sleep patterns and regulate unconscious but essential functions, such as breathing and blood circulation.
Homogeneous
composed of similar or identical parts; of uniform nature.
Human leukocyte antigens (HLA)
proteins on the outer part of body cells that help fight illness. These proteins vary from person to person.
Hypoglycaemia
an abnormally low concentration of glucose in the blood.

I

Impairment
loss or abnormality of psychological, physiological or anatomical structure or function. The impairment may be undetected by the individual and be discovered by clinical observation. This compares to disability, where the loss or abnormality (the impairment) has an effect on the ability to perform an activity.
Infusion
fluid allowed to flow into a vein (in the case of IV) or muscle (IM).
Inheritance
inheritance is the acquisition of characters or qualities by transmission from parent to offspring. Mendel derived two laws; the members of a pair of allelic genes segregate from one another and pass to different gametes, and genes that are not alleles are distributed to the gametes independently of one another.
Insulin
a hormone that controls the sugar concentration in the body. Deficiency leads to diabetes. Insulin can be produced by genetic engineering.
Interferon-beta-1b
a modified, recombinant, non-glycosylated version of beta interferon, (i.e. it has not undergone glycosylation), which has similar biological activity to natural human beta interferon.
Interleukins
a group of molecules involved in signalling between cells of the immune system.
Intrathecal
within a sheath, for example, cerebrospinal fluid is contained within the dura mater. It also refers to drugs administered into the cerebrospinal fluid bathing the spinal cord and brain.
Intravenous
within a vein or veins.
In vitro
in a test tube or other artificial laboratory environment.
In vivo
within the living body.
Ischaemia
a low oxygen state usually due to the obstruction of the arterial blood supply or inadequate blood flow.

K

Kurtzke scale
neurological rating scale devised by John Kurtzke in 1955 as the Disability Status Scale upon which the EDSS is based.

L

Lateral
a position farther from the median plane or midline of the body.
Lesion
an area of tissue with impaired function as a result of damage by disease or wounding. Lesions in MS are found in the brain and spinal cord.
Locus
the site on a chromosome where the gene for a particular trait is located. Any one of the alleles of a gene may be present at this site.
Lumbar puncture
a puncture of the lower region of the spinal cord to withdraw cerebrospinal fluid or inject anaesthetic drugs. It is also known as a "spinal tap".
Lymphocytes
a major group of cells involved in the immune system, found in the blood, lymph and lymphoid tissue.
Lysis
rupture of cell membranes and loss of cytoplasm.

M

Macrophages
specialised cells involved in phagocytosis.
Major histocompatibility complex (MHC)
the set of gene loci specifying a set of cell surface antigens.
Mammalian cells
some cells isolated from mammalian tissues can be grown in culture on an industrial scale.
Meninges
membranous covering that protect the central nervous system. There are three meninges; the outermost layer is the dura mater, the middle layer is the arachnoid mater and the innermost layer is the pia mater.
Metabolites
any substance produced by metabolism or by a metabolic process.
Metabolize
to break down substances by chemical reactions inside the body.
Micturition
the passage of urine, urination.
Monozygotic
identical twins, twins which are the result of a single fertilised egg (zygote) splitting into two cell masses and becoming two individuals. The twins are genetically identical and are always of the same sex (both males or both females).
Motor neurones
neurones that control movement, either voluntary or involuntary.
Multifactorial
arising through the action of many factors.
Multiple Sclerosis
a disease involving the brain and spinal cord, in which there are places of damage or loss of the myelin coating on nerves (demyelination). The demyelination can be of various sizes - from the size of a pin-head to that of a pea, or larger. The symptoms depend on where the patches of demyelination occur.
Mutation
a permanent transmissible change in the genetic material, usually in a single gene.
Myelin
coating around nerve cells that provides protection and insulation.
Myocardial infarction
a term used to describe irreversible injury to heart muscle (heart attack).

N

Necrosis
the sum of the morphological changes indicative of cell death.
Neurodegenerative diseases
diseases marked by nerve deterioration (degeneration), such as MS, Parkinson's disease, motor neurone disease and Alzheimer's disease.
Neurotransmitters
a substance released from a neurone that passes across a synapse to either excite or inhibit a target cell.
Node of Ranvier
small gap between adjacent segments of myelin.
Nucleic acid
a generic term for DNA or RNA. Nucleic acids are composed of repeating units to form the long chains seen in the DNA double helix, or the structure of RNA.
Nystagmus
an involuntary, rapid, rhythmic movement of the eyeball.

O

Oedema
swelling due to the presence of abnormally large amounts of fluid.
Oligoclonal bands
different antibody molecules seen as separate bands when subjected to electrophoresis, a technique that tracks the motion of charged particles through a polymer matrix under the influence of an applied electrical field. The particles separate based on their size. In MS, when a patient's CSF, containing elevated levels of antibody, undergoes electrophoresis, the antibodies fractionate into oligoclonal bands, representing species of antibody molecules. However, not all MS patients have oligoclonal bands, and the presence of oligoclonal bands is not specific for MS.
Optic neuritis
inflammation of the optic nerve.

P

Paraclinical
performed outside the clinical setting, i.e. not in the doctor's office. Paraclinical tests can be performed in a laboratory (e.g. a blood test) or by using special instruments (e.g. an X-ray or an MRI scan).
Paresis
slight or incomplete paralysis.
Paraesthesia
abnormal neurological sensations, which include numbness, tingling, burning, prickling and hyperesthesia (increased sensitivity).
Paroxysmal
recurring in spasms or seizures.
Pathogens
any disease producing microorganism.
Pathology
the abnormalities in the body caused by disease.
Pathophysiology
the study of disordered function of a living organism - the basic processes underlying the function of a species, and the physical and chemical factors and processes involved.
Pedigree analyses
a table, chart, diagram, or list of an individual’s ancestors, used in the analysis of inheritance.
Penetrance
the proportion of individuals with a specific set of genes (genotype) who express that character in the phenotype.
Phagocytosis
the process by which cells engulf material and enclose it within a vacuole (phagosome) in the cytoplasm.
Pharmacodynamics
the effects of the drug on the human body. You can think of it as 'what the drug does to the body', as compared with pharmacokinetics ('what the body does to the drug').
Pharmacokinetics
derives its meaning from its roots 'pharmaco' meaning drug and 'kinetic' meaning movement. It is the study of the absorption, distribution, metabolism and excretion of a drug. You can think of it as 'what the body does to the drug', as compared with pharmacodynamics ('what the drug does to the body').
Phenotype
the entire physical, biochemical and physiological makeup of an individual as determined both genetically and environmentally.
Physiological
concerning body functions.
Placebo
an inactive substance given as a control in the testing of a new drug. It is given in the same way as and in an identical form to the active drug (e.g. intravenously, in a yellow pill, as a green liquid).
Plasmid
bacterial DNA found in a discrete loop in the cytoplasm, which is additional to the main bulk of bacterial DNA found in chromosomes. Plasmids may be important in bacterial resistance to antibiotics, because genes can be passed from one bacterium to another in a plasmid. This gene-passing property is used by biotechnologists to implant useful genes in bacteria.
Plaque
area of scar tissue in the brain or spinal cord; also called a lesion.
Pneumonia
inflammation of the lungs with consolidation.
Polygenic
determined by the action of several different genes.
Polymorphisms
the regular and simultaneous occurrence in a single interbreeding population of two or more alleles of a gene, where the frequency of the rarer alleles is greater than can be explained by recurrent mutation alone (typically greater than 1%).
Prevalence
the number of people with the disease at a particular time. It usually expressed in numbers of people with disease per 100,000 of the population.
Primary progressive MS
people with this type of MS do not normally experience distinct relapses, remissions, or recovery, but become progressively more disabled over time. This form of MS is common in people who develop the disease after the age of 40 years (about 25% of all MS patients). Primary progressive MS is one of four types of MS (benign, relapsing-remitting, secondary progressive).
Protein
a large molecule composed of amino-acid building blocks linked in a string and twisted into a complex shape.
Proton
a particle found in the nucleus of an atom, which has a positive charge identical in magnitude to the negative charge of an electron. The proton forms, by itself, the nucleus of the hydrogen atom.
Proton density scan
a type of MRI scan where the radiowave pulses are altered such that MS lesions near the ventricles may be seen more clearly.
Purification
isolating a single type of protein from all other proteins and any other contaminants.
Psychological
concerning the mind.
Psychosis
a general term used to refer to mental disorders in which mental functioning is sufficiently impaired as to interfere grossly with the patient’s capacity to meet the ordinary demands of life.

R

Receptor
a molecular structure within or on the surface of a cell that selectively binds to a specific substance and results in a specific physiologic effect.
Recombinant
derived from two different sources. Recombinant proteins are made from DNA combined from two different sources through genetic engineering, not through breeding experiments.
Relapsing-remitting MS
one of four types of MS (benign, primary progressive, secondary progressive), characterised by relapses followed by periods of remission with complete or near complete recovery. Overall disability usually gradually accumulates over time.
Renal
pertaining to the kidney.
Restriction endonuclease
a group of enzymes found in bacteria that recognise specific sequences of bases in DNA, and cut the chain every time this sequence appears. The result is a series of predictable DNA fragments. Different restriction endonucleases cut DNA at different places.
Retrobulbar neuritis
inflammation behind the eyeball.
Reverse transcriptase
a viral enzyme that can reverse the normal direction of information transfer. Normally, genetic information passes from DNA to RNA to protein (the central dogma of Francis Crick), but reverse transcriptase synthesises DNA from RNA.
Rhizotomy
surgical interruption of a spinal or cranial (brain) nerve root.
Ribonucleic acid (RNA)
a single-stranded nucleic acid containing the sugar ribose. RNA is responsible for transferring genetic information from DNA in the nucleus to the ribosomes in the cytoplasm, where it is used as the instructions for building proteins.
Ribosome
a particle in the cytoplasm, containing RNA and protein, which is the site of protein synthesis.

S

Scanning speech
Abnormal speech characterized by staccato-like articulation that sounds clipped because the person unintentionally pauses between syllables and skips some of the sounds.
Sclerosis
Hardening of tissue. In MS, sclerosis is the body's replacement of lost myelin around CNS nerve cells with scar tissue.
Secondary progressive multiple sclerosis
In some instances, people who begin with a relapsing/remitting form of MS may find that over time the symptoms which they are experiencing increase. This may be a case of the remaining symptoms after each attack increasing over time, or the relapsing/remitting pattern may be replaced by a progressive pattern.
Sensory
Related to bodily sensations such as pain, smell, taste, temperature, vision, hearing, acceleration and position in space.
Spasticity
The loss of normal elasticity in the muscles of the legs and/or arms as a result of disease in the central nervous system. It often results in extreme stiffness of the muscles.
Symptom
A subjectively perceived problem or complaint reported by the patient. In multiple sclerosis, common symptoms include visual problems, fatigue, sensory changes, weakness or paralysis of limb, tremor, lack of coordination, poor balance, bladder or bowel changes, and psychological changes.

T

T1-weighted scan
a type of MRI scan where the radiowave pulses are altered such that old lesions are seen more easily. When used with a contrast agent, new lesions can also be seen.
T2-weighted scan
a type of MRI scan where the radiowave pulses are altered such that all lesions are shown, both new and old it is often used in diagnosing MS. Areas with a high water content (e.g. MS lesions, fluid-filled ventricles) give a strong bright signal.
T-cell
a class of lymphocytes, involved primarily in controlling cell-mediated immune reactions and in the control of B-cell development. The T-cells co-ordinate the immune system by secreting lymphokine hormones.
Tetany
hyperexcitability of nerves and muscles characterised by muscular twitches and cramps.
Tic
an involuntary, compulsive, repetitive, stereotyped movement, usually involving the face and shoulders.
Tissue plasminogen activator
a factor released into blood vessels, which activates a blood enzyme called plasminogen, which digests blood clots and improves blood flow. Recombinant tissue plasminogen activator is used in the treatment of medical emergencies such as heart attacks and strokes.
Tonic seizure
a type of seizure that is characterized by continuous tension.
Transcription
the process by which genetic information is transferred (transcribed) from DNA to RNA.
Transfection
the process of transplanting DNA from one species into a cell from a different species.
Translation
the conversion of a coded message (in RNA) for the sequence of amino acids in a protein into the protein itself.
Transmissable
capable of being transmitted from one individual or one species to another.
Tumour necrosis factor
a cytokine activated by T-cells, which preferentially kills tumour cells in vivo and in vitro.

V

Vasodilation
the increase in the internal diameter of a blood vessel causing an increase in blood flow.
Ventricles
the cavities within the brain, which are filled with cerebrospinal fluid.
Venule
a small vein.
Virus
a tiny infective particle consisting of DNA wrapped in a protective protein sheath.

W

White Matter
part of the brain and spinal cord made up of nerve fibres.

Y

Yeld
the amount of substance produced in a given time.