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acute phase
A short, sharp, and relatively severe course of a disease; not chronic.

Addison's disease
A disease marked by the atrophy or destruction of the adrenal cortex. Most cases of Addison's disease appear to involve an autoimmune process.

alanine aminotransferase (a. transaminase; ALT)
aminotransferases are enzymes that facilitate the conversion of one amino acid into another, thus helping to maintain a balanced supply of amino acid building blocks for protein synthesis. Elevated alanine amino transferase activity provides a useful indicator for liver disorders.

A type of protein widely distributed in the tissues and fluids of plants and animals. It is the single most abundant protein in blood. Albumin acts as a carrier for numerous substances in the blood.

alkaline phosphatase
A group of enzymes that belong to the class known as hydrolases. They are thought to play an important role in the transport of sugars and phosphates in the intestine, bone, kidney and placenta. Elevated serum levels of alkaline phosphatase activity may indicate liver disease.

amino acid
A family of modified organic acids that serve as building blocks for the synthesis of proteins.

An enzyme that breaks down complex carbohydrates such as starch.

anaphylactic shock
An allergic reaction marked by contraction of smooth muscle and dilation of blood vessels. If not checked rapidly by an injection of epinephrine, the reaction can be lethal.

anorexia nervosa
A personality disorder manifested by extreme aversion to food, usually occurring in young women.

Moving forward.

Pharmaceutical agents used to treat clinical depression.

Agents that reduce inflammation without directly antagonizing the agent that caused it.

antinuclear antibody
Anti-self antibodies directed against the DNA. It is one indicator for the autoimmune disorder systemic lupus erythematosis (SLE).

anxiety disorders
Also known as anxiety neurosis or anxiety reaction. A condition that can be caused by both psychologic and physiologic factors. It can take two general forms: (1) acute anxiety (panic disorder), marked by repeated occurrences of intense self-limited anxiety lasting usually a few minutes to an hour, or (2) chronic anxiety, characterized by less intense reactions of much longer duration (days, weeks, or months).

A disease marked by recurrent attacks of distressed breathing. It is most often due to allergic reactions to plant or animal substances or to food products.

autoimmune disease
Disorders in which the body mounts a destructive immune response against its own tissues.

axillary lymph nodes
Lymphoid organs located near the shoulder joint.

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bile duct
Tubular structures responsible for conducting bile (a substance that aids in digestion) from the liver to the intestine.

biliary obstruction
Blockage or clogging of a bile duct.

A red pigment formed from hemoglobin during normal and abnormal destruction of red blood cells in the body.

bipolar affective disorder
A mood disorder that commonly begins with depression and is characterized by at least one period of elation sometime during the course of the illness.

A genus of bacteria with numerous species that cause disease in humans. The diseases associated with these organisms are typically relapsing fevers.

bulimia nervosa
A disorder marked by morbidly increased appetite, often alternating with periods of anorexia.

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Candida albicans
A common saprophyte of the digestive tract and female urogenital tract. It does not ordinarily cause disease, but may do so following a disruption of bacterial flora of the body, or in patients with depressed immune systems.

case-control study
An epidemiologic study that examines selected patients who have a defined disease (cases) with persons without the disease (controls).

case definition
In the example of CFS, a combination of symptoms, signs, and physiologic characteristics that serve to distinguish a case of chronic fatigue syndrome from other disease states.

cervical lymph nodes
Lymphoid organs located in the neck.

Inflammation of the bile duct.

Inflammation of the gall bladder.

Of long duration, denoting a disease of slow progress and long continuance.

chronic fatigue and immune dysfunction syndrome (CFIDS)
A synonym for chronic fatigue syndrome used by some patients and physicians. It should be stressed, however, that no immune dysfunction or aberration has been persuasively linked to chronic fatigue syndrome.

Progressive disease of the liver, characterized by liver cell damage, scarring of the liver, and abnormal liver architecture and function.

cluster investigation
An epidemiologic investigation mounted to determine if there has been an unexpected increase in the number or prevalence of cases of illness. The increase can be with respect to a particular interval in time, a particular location, or both.

A substance that enhances or is necessary for the action of enzymes. They are generally much smaller than enzymes themselves.

Two or more disease conditions that occur simultaneously within the same person. A diagnosis of CFS requires that certain other conditions that may also cause fatigue, such as cancer, are not present.

connective tissue
The supporting tissues of the body, such as tendons, ligaments, bone, and cartilage.

connective tissue disorder
A variety of inflammatory diseases of connective tissue, the most common of which is rheumatoid arthritis. Much, if not all, of this disease is now attributed to autoimmune processes.

A device used to verify or regulate a scientific experiment or study. A case-control study serves as a useful example. Since patients with a specific illness are examined for various characteristics, a group of healthy individuals who otherwise have as much in common with the patients as possible must be examined in parallel for the same characteristics.

A component of urine, and the final breakdown product of creatine, which is an important molecule for building energy reserves, for example, in muscle cells.

cross-sectional study
In epidemiology, a study in which participants are examined at only a single time for characteristics of a disease.

Proteins manufactured by cells of various lineages that, when secreted, drive specific responses (e.g., proliferation, growth, or maturation) in other susceptible cells.

cytomegalovirus (CMV)
One of the eight known types of human herpesviruses, also known as human herpesvirus 5 (HHV-5). It belongs to the beta subfamily of herpesviruses. CMV can cause severe disease in patients with immune deficiency and in newborns when the virus is transmitted in utero.

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A neurotic or psychotic condition marked by an inability to concentrate, insomnia, and feelings of dejection and guilt.

diabetes mellitus
A metabolic disease in which carbohydrate utilization is reduced and fat and protein utilization is enhanced. It is caused by insulin deficiency.

diabetic acidosis
A condition in diabetic patients in which the levels of alkali are reduced relative to the level of acids.

diabetic ketoacidosis
A form of acidosis in diabetic patients caused by the enhanced production of ketone bodies.

diabetic nephrosclerosis
A condition in diabetic patients marked by hardening of the kidney from overgrowth and contraction of the connective tissue of the organ.

delusional disorders
A psychiatric disorder characterized by states of heightened self-awareness and a tendency toward paranoia.

A physically caused permanent or progressive decline in intellectual function that interferes with the patient's normal social or economic activity.

Agents that promote the excretion of and/or increase the amount of urine.

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Substances that dissociate in water to form a cation (positively charged ion) and and anion (negatively charged ion). Charged ions are central to a variety of important processes in the body, including muscle contraction and nerve impulse conduction.

A genus of RNA viruses with over 70 types identified in humans. They reproduce in the intestinal tract, and various members can cause a variety of human diseases, including poliomyelitis, aseptic meningitis, hepatitis, inflammatory heart disease, and rhinitis.

Specialized proteins that act as catalysts for virtually all necessary chemical reactions that take place within the body. Like all catalysts, enzymes unchanged by the reactions they promote, and will initiate many reactions until they are degraded (usually by another enzyme).

A white cell of the category known as granulocytes. These cells contain numerous dense granules in their cytoplasm that comprise a battery of highly active digestive chemicals and toxins. Their chief role is thought to be in combatting large parasites, although occasionally their activity may be triggered by other agents, potentially leading to damage of normal tissues (see eosinophilia myalgia syndrome).

eosinophilia myalgia syndrome (EMS)
A disease caused by marked promotion of eosinophil activity, resulting in a symptom complex of severe pain, inflammation of the tendons, fluid build-up in the muscles, and skin rash. The disorder has been linked to a contaminant of some commercial preparations of the amino acid L-tryptophan.

The branch of medical science that deals with the incidence, distribution, and control of disease in a population.

Epstein-Barr virus (EBV)
One of the eight known types of human herpesviruses, also known as human herpesvirus 4 (HHV-4). It belongs to the gamma subfamily of herpesviruses. It commonly causes acute mononucleosis, and less commonly chronic mononucleosis. It some populations EBV is causally associated with life-threatening malignancies (Burkitt's lymphoma, nasopharyngial carcinoma).

Causal association of a disease with an agent. The study of the cause of diseases.

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Also known as myofascial pain syndrome and fibromyositis. A group of common rheumatoid disorders (not involving the joints) characterized by achy pain, tenderness, and stiffness of muscles.

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gamma (g) glutamyl transferase
One of a family of enzymes involved in transporting amino acids from the exterior to the cytoplasm of a cell. High serum levels of this enzyme serve as an indicator for liver disease.

A family of proteins found in abundance in plasma. They include the gamma globulins, which in turn include the various antibody molecules produced by the immune system.

Kidney disease characterized by bilateral inflammatory changes in the glomeruli (tufts of capillary loops associated with the nephrons, the functional units of the kidney). The disorder is not caused by infection. It is considered an autoimmune disease.

A simple sugar which is actively transferred into the blood following the digestive breakdown of starch and other carbohydrates in the gut.

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Having to do with the blood.

The red, oxygen-carrying protein found in red blood cells.

hepatitis B virus
A small DNA virus capable of causing both acute and chronic liver disease, possibly by eliciting tissue damage by the immune system. The virus may also be a risk factor for hepatic carcinoma. It is often transmitted through sexual activity or through exposure to contaminated blood.

hepatitis C virus
An RNA virus related to the pestiviruses and flaviviruses. It is capable of causing both acute and chronic liver disease. As with hepatitis B, the liver damage resulting from this infection may be the result of immune reactivity against virus-infected liver cells.

A family of large DNA viruses that infect a wide range of animal species. Eight distinct types have been associated with a variety of human diseases.

human herpesvirus 6
A virus of the herpesvirus beta-subfamily, discovered in 1985, that infects more than 95% of people by the age of 2 years. It has been causally associated with roseola, mononucleosis-like illness, inflammation of lymph glands. There is also suggestive evidence for a role in multiple sclerosis.

A condition marked by excessive secretory activity of the thyroid gland.

A condition caused by the rEducation or absence of secretions of the parathyroid gland.

Diminished production of thyroid hormone, leading to thyroid insufficiency.

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Related to an abnormal state or condition produced in a patient through inadvertant or erroneous treatment.

Denoting a disease of unknown cause.

imaging tests
Any of a variety of methods for observing the internal anatomy of the body, ranging from simple x-rays to complex three-dimensional scanning techniques using nuclear magnetic resonance, positron emission, and other techniques.

immune globulin
A crude preparation of antibody molecules collected from pooled multiple blood donations, used as a means for passively transferring antimicrobial resistance to susceptible individuals.

immune suppressants
Agents that block or restrict the activity of one or more components of the immune system, usually leading to increased susceptibility to infectious disease.

Inability to sleep even in the absence of external impediments, during the period when sleep should normally occur.

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An ester of lactic acid produced during non-respiratory glucose combustion. It may accumulate during some disease conditions, leading to lactate acidosis.

lactate dehydrogenase
An enzyme important to the process of glucose combustion in the body, and an important mechanism for cellular energy production.

Lyme disease
A tick-transmitted inflammatory disorder that begins with a characteristic skin rash, and may be followed weeks to months later by neurologic, cardiac, or joint abnormalities.

Denoting a virus that tends to bind to and infects one or more subsets of lymphocytes.

lymph node
Secondary immune organs distributed at discrete locations throughout the body. These organs play a central role in the activation and trafficking of immune lymphocytes in the body.

Small white blood cells that are uniform in appearance, but very diverse in function. Collectively, they are responsible for antibody production, direct cell-mediated killing of virus-infected cells and tumor cells, and for the regulation of virtually every other component of the mammalian immune system.

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magnetic resonance imaging
The use of nuclear magnetic resonance of protons to produce cross-sectional proton density images of internal structures of the human body.

malabsorption syndrome
Syndromes resulting from impaired absorption of nutrients from the bowel.

A feeling of general discomfort or uneasiness, an out-of-sorts feeling, often the first indication of an infection or other disease.

multiple chemical sensitivity disorder
A controversial diagnosis of an allergy-like sensitivity to an unusually broad range and number of substances. This condition has not been subjected to rigorous scientific scrutiny, and there is considerable doubt as to whether or not it actually exists.

multiple sclerosis
A slowly progressive central nervous system disease characterized by disseminated patches of demyelination in the brain and spinal cord.

myalgic encephalomyelitis
A synonym for chronic fatigue syndrome in common usage in the United Kingdom and Canada.

The oxygen-transporting protein of muscle, resembling blood hemoglobin in function.

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A sudden, uncontrollable disposition to sleep occurring at irregular intervals, with or without obvious predisposing or exciting cause.

natural killer cell (NK)
A lymphocyte which, unlike other lymphocytes, does not require specific activation by foreign antigen. They are considered to play a "front line" role in controlling infection, curbing infection until a specific, coordinated immune response can be mounted.

Nervous exhaustion. A functional neurosis marked by intense nervous irritability and weakness.

Muscular weakness, usually of emotional origin.

Relating to organic and functional diseases of the nervous system.

Substances produced in neurons that promote or inhibit the conduction of nerve impulses, such as epinephrine, norepinephrine, dopamine, serotonin, and gamma-aminobutyrate.

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Osmotic concentration. An indicator of fluid balance in the bodies tissues.

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Characteristic or indicative of a disease, denoting especially one or more typical symptoms.

Characteristic derangement of function seen in disease.

period prevalence
The number of existing cases of an illness during a period or interval, divided by the average population.

Also known as the hypophysis, a gland at the base of the brain with two functionally distinct lobes involved in regulating growth, metabolism, and maturation.

The fluid portion of the blood, rich in soluble proteins with a wide range of functions.

positron emission tomography (PET scan)
Imaging technique that relies on the detection of gamma rays emitted from tissues after administration of a natural biochemical substance into which positron-emitting isotopes have been incorporated.

Relating to the lungs.

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radionuclide scans
Any of a variety of medical imaging methods that rely on atomic isotopes that decay and emit radiation.

Relating to the kidneys.

A family of RNA viruses that have the unique characteristic of producing an enzyme that makes a DNA copy of its genetic information from an RNA template (the opposite of what normally takes place). The most widely recognized of these viruses is HIV, the causative agent in AIDS. Another virus from this family (HTLV-1) has been associated with T cell leukemia. Initial reports of an association of an HTLV-II-like retrovirus with CFS could not be confirmed in subsequent studies.

Also known as roseola infantum, exanthem subitem, and pseudorubella. An acute disease of infants or very young children caused by HHV-6 and characterized by high fever and a skin rash.

Also known as German measles, an acute disease marked by skin rash and swollen lymph nodes, but generally without fever. It is caused by an RNA virus of the togavirus family.

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A systemic disease involving the lungs, lymph nodes, skin, liver, spleen, eyes, phalangial bones, and parotid glands, characterized by granular nodules. Its cause is not known.

The most common type of psychosis, characterized by extensive withdrawal of the individual's interest from other people and the outside world and the investment of it in his/her own self.

sentinel surveillance
A monitoring method that employs a surrogate indicator for a public health problem, allowing estimation of the magnitude of the problem in the general population.

Morbid conditions following as a consequence of a disease.

single photon emission computed tomography (SPECT) scan
An imaging technique that measures the emission of photons of a given energy from radioactive tracers introduced into the body. As with other forms of computer-assisted tomography, the technique produces a series of cross-sectional images of internal anatomy.

Inflammation of the lining membrane of any sinus, especially of one of the paranasal sinuses.

sleep apnea
A group of potentially lethal disorders in which breathing recurrently stops during sleep for long enough to cause measurable blood deoxygenation.

A zone between acute and chronic, denoting the course of a disease.

An acute and chronic disease caused by the bacteria Treponema pallidum, transmitted by direct contact, usually through sexual intercourse.

systemic lupus erythematosus
An inflammatory disease of connective tissue occurring predominantly in women (90%). It is considered to be an autoimmune disease.

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T lymphocyte, T cell
The most common type of lymphocyte, itself divided into at least three subpopulations on the basis of function — cytotoxic, or killer T lymphocytes, helper T lymphocytes, and suppressor T lymphocytes. T cells play a cardinal role in regulating the immune system.

A two-lobed structure located in front of and on either side of the trachea, producing the hormone thryoxin; of or relating to the thyroid gland.

thyroid-stimulating hormone
A hormone of the anterior pituitary gland that stimulates and regulates the development and secretory activity of the thyroid gland.

Poisoning from hyperthyroidism.

The concentration of a substance in a solution, or the strength of such a substance detected by titration. In the current context, the term is most likely to refer to antibody titer, which is a measure of the concentration of specific antibodies to selected microbes that are circulating in an individual's bloodstream.

An abnormal mass of tissue that grows more rapidly than normal, and continues to grow after the stimuli which initiated the new growth cease.

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The chief product of nitrogen metabolism in mammals, excreted in the urine. Carbonyl diamide.

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A group of organic micronutrients, present in minute quantities in natural foodstuffs, that are essential to normal metabolism.

vitamin D deficiency
(ricketts and osteomalacia) In children, the condition prevents normal bone development; in adults, a lack of vitamin D causes demineralization of bone, particularly in the spine, pelvis, and lower extremities.

vitamin D intoxication
A disorder marked by weight loss, nausea, vomiting, and impaired renal function.

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Page last modified on May 3, 2006

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