Micronutrient Information Center
Glossary
- Acetylation
- the addition of an acetyl group (-COCH3) group
to a molecule.
- Acidic
- having a pH of less than 7.
- Acute
- having a short and relatively severe course.
- Adjunct therapy
- a treatment or therapy used in addition to another, not alone.
- Adrenal glands
- a pair of small glands, located above the kidneys, consisting of an
outer cortex and inner medulla. The adrenal cortex secretes cortisone-related
hormones and the adrenal medulla secretes epinephrine (adrenaline) and
norepinephrine (noradrenaline).
- Aglycone
- the nonsugar component of a glycoside. Cleavage of the glycosidic
bond of a glycoside results in the formation of a sugar and an aglycone.
- AI
- adequate intake. Established by the Food and Nutrition Board of the
US Institute of Medicine, the AI is a recommended intake value based
on observed or experimentally determined estimates of nutrient intake
by a group of healthy people that are assumed to be adequate. An AI
is established when an RDA cannot be determined.
- AIDS
- acquired immune deficiency syndrome. AIDS is caused by the HIV (Human
Immunodeficiency Virus) virus, which attacks the immune system, leaving
the infected individual vulnerable to opportunistic infection.
- Alkaline
- basic; having a pH of more than 7.
- Alkaloid
- a plant-derived compound that is biologically active, contains a nitrogen
in a heterocyclic ring, is alkaline, has a complex structure, and is
of limited distribution in the plant kingdom.
- Allele
- One of a set of alternative forms of a gene. Diploid cells possess
two homologous chromosomes (one derived from each parent) and therefore
two copies of each gene. In a diploid cell, a gene will have two alleles,
each occupying the same position on homologous chromosomes.
- Alzheimer's disease
- the most common cause of dementia in older adults. Alzheimer’s disease
is characterized by the formation of amyloid plaque in the brain and
nerve cell degeneration. Symptoms include memory loss and confusion,
which worsen over time.
- Amino acids
- organic (carbon-containing) molecules that serve as the building blocks
of proteins.
- Amyloid plaque
- aggregates of a peptide called amyloid-beta, which accumulate and
form deposits in the brain in Alzheimer’s disease.
- Anaerobic
- refers to the absence of oxygen or the absence of a need for oxygen.
- Analog
- a chemical compound that is structurally similar to another but differs
slightly in composition (e.g., the replacement of one functional group
by another).
- Anaphylaxis
- a rapidly developing and severe systemic allergic reaction. Symptoms
may include swelling of the tongue, throat, and trachea, which can result
in difficulty breathing, shock and loss of consciousness. If not treated
rapidly, anaphylaxis can be fatal.
- Anemia
- the condition of having less than the normal number of red blood
cells or hemoglobin in the blood, resulting in diminished oxygen transport.
Anemia has many cause, including: iron, vitamin B-12, or folate deficiency,
bleeding, abnormal hemoglobin formation (e.g., sickle cell anemia),
rupture of red blood cells (hemolytic anemia), and bone marrow diseases.
- Anencephaly
- a birth defect, known as a neural tube defect, resulting from failure
of the upper end of the neural tube to close during embryonic development.
Anencephaly is a devastating and sometimes fatal birth defect resulting
in the absence of most or all of the cerebral hemispheres of the brain.
- Angina pectoris
- pain generally experienced in the chest, but sometimes radiating to
the arms or jaw, due to a lack of oxygen supply to the heart muscle.
- Angiogenesis
- the development of new blood vessels.
- Angiography (coronary)
- imaging of the coronary arteries used to identify the location and
severity of any obstructions. Coronary angiography typically involves
the administration of a contrast medium and imaging of the coronary
arteries using an X-ray based technique.
- Anion
- a negatively charged ion.
- Antagonist
- a substance that counteracts or nullifies the biological effects of
another, such as a compound that binds to a receptor but does not elicit
a biological response.
- Antibodies
- specialized proteins produced by white blood cells (lymphocytes) that
recognize and bind to foreign proteins or pathogens in order to neutralize
them or mark them for destruction.
- Anticoagulant
- a class of compounds that inhibit blood clotting.
- Anticonvulsant
- a class of medication used to prevent seizures.
- Antigen
- a substance that is capable of eliciting an immune response.
- Antihistamine
- a chemical that blocks the affect of histamine in a susceptible tissues.
Histamine is released by immune cells during an allergic reaction and
also during infection with viruses which cause the common cold.
The interaction of histamine with the mucus membranes of the eyes and
nose results in "watery eyes" and the "runny nose"
often accompanying allergies and colds. Antihistamines can alleviate
such symptoms.
- Antioxidant
- any substance that prevents or reduces damage caused by reactive
oxygen species (ROS) or reactive
nitrogen species (RNS).
- Antiresorptive agents
- medications or hormones that inhibit bone resorption.
- Apoptosis
- gene-directed cell death or programmed cell death that occurs when
age, condition, or state of cell health dictates. Cells that die by
apoptosis do not usually elicit the inflammatory responses that are
associated with necrosis. Cancer cells are resistant
to apoptosis.
- Arrhythmia
- an abnormal heart rhythm. The heart rhythm may be too fast (tachycardia),
too slow (bradycardia) or irregular. Some arrhythmias, such as ventricular
fibrillation, may lead to cardiac arrest if not treated promptly.
- Asthma
- a chronic inflammatory disease of the airways, characterized by recurrent
episodes of reversible airflow obstruction.
- Ataxia
- a lack of coordination or unsteadiness usually related to a disturbance
in the cerebellum, a part of the brain that regulates coordination and
equilibrium.
- Atherosclerosis
- an inflammatory disease resulting in the accumulation of cholesterol-laden
plaque in artery walls. Rupture of atherosclerotic plaque results in
clot formation, which may result in myocardial infarction or ischemic
stroke.
- ATP
- adenosine triphosphate. An important compound for the storage of
energy in cells, as well as the synthesis of nucleic
acids.
- Atria
- (singular: atrium) two upper chambers of the heart that receive blood
from the veins and contract to force that blood into the ventricles.
- Atrial fibrillation
- a cardiac arrhythmia, characterized by
rapid, uncoordinated beating of the atria, which
results in ineffective atrial contractions. Atrial fibrillation is known
as a supraventricular arrhythmia because it originates above the ventricles.
- Atrophic gastritis
- a chronic inflammation of the lining of the stomach, which ultimately
results in the loss of glands in the stomach (atrophy) and decreased
stomach acid production.
- Atrophy
- decrease in size or wasting away of a body part or tissue.
- Autoimmune disease
- A condition in which the body's immune system reacts against its
own tissues.
- Autophosphorylation
- The phosphorylation by a protein of one or more of its own amino acid residues.
Autophosphorylation does not necessarily occur on the same polypeptide chain as the
catalytic site. In a dimer, one subunit may phosphorylate the other.
- Autosomal
- refers to a trait or gene that is not located on the X or Y chromosome
(not sex-linked).
- Bacteria
- single-celled organisms that can exist independently, symbiotically
(in cooperation with another organism) or parasitically (dependent upon
another organism, sometimes to the detriment of the other organism).
Examples of bacteria include acidophilus (found in yogurt), streptococcus
the cause of strep throat, and E. coli (a normal intestinal bacteria,
as well as a disease-causing agent).
- Balance study
- a nutritional balance study involves the measurement of the intake
of a specific nutrient as well as the elimination of that nutrient in
urine, feces, sweat, etc. If intake is greater than loss of a particular
nutrient the individual is said to be in "positive balance."
If intake is less than loss, an individual is said to be in "negative
balance" for the nutrient of interest.
- Benign prostatic
hyperplasia
- the term used to describe a noncancerous enlargement of the prostate.
- Bias
- any systematic error in an epidemiological study that results in an
incorrect estimate of the association between an exposure and disease
risk.
- Bile
- a yellow, green fluid made in the liver and stored in the gallbladder.
Bile may then pass through the common bile duct into the small intestine
where some of its components aid in the digestion of fat.
- Bile acids
- components of bile, which are formed by the metabolism of cholesterol,
and aid in the digestion of fats.
- Bioavailability
- the fraction of an administered compound that reaches the systemic
circulation and is transported to site of action (target tissue).
- Biomarker
- a physical, functional, or biochemical indicator of a physiological
or disease process.
- Biotransformation enzymes
(phase I and phase II)
- enzymes involved in the metabolism and elimination of a variety of
exogenous (drugs, toxins and carcinogens) and endogenous compounds (steroid
hormones). In general, phase I biotransformation enzymes, including
those of the cytochrome P450 family, catalyze reactions that increase
the reactivity of fat-soluble compounds and prepare them for reactions
catalyzed by phase II biotransformation enzymes. Reactions catalyzed
by phase II enzymes generally increase water solubility and promote
the elimination of these compounds.
- Bipolar disorder
- a mood previously called “manic-depressive illness.” Bipolar disorder
is characterized by severe alterations in mood. During “manic” episodes,
a person may experience extreme elevation in energy level and mood (euphoria)
or extreme agitation and irritability. Episodes of depressed mood are
also common in bipolar disorder.
- Body mass index (BMI)
- body weight in kilograms divided by height in meters squared. In adults, BMI is a measure of body fat: underweight, <18.5; normal weight, 18.5-24.9; overweight, 25-29.9; obese, ≥ 30. Calculate your BMI.
- Bone mineral density (BMD)
- the amount of mineral in a given area of bone. BMD is positively associated
with bone strength and resistance to fracture, and measurements of BMD
are used to diagnose osteoporosis.
- Bone remodeling
- the continuous turnover process of bone that includes bone resorption
and bone formation. An imbalance in the regulation of bone remodeling's
two contrasting events, bone resorption and bone formation, increases
the fragility of bone and may lead to osteoporosis
- Bronchitis, chronic
- long-standing inflammation of the airways, characterized by excess
production of sputum, leading to a chronic cough and obstruction of
air flow. Cigarette smoking is the most common cause of chronic bronchitis.
- Buffer
- a chemical used to maintain the pH of a system by
absorbing hydrogen ions (which would make it more acidic)
or absorbing hydroxyl ions (which would make it more alkaline).
- C-reactive protein (CRP)
- a protein that is produced in the liver in response to inflammation.
CRP is a biomarker of inflammation that is strongly associated with
the risk of cardiovascular events, such as myocardial infarction and
stroke.
- Calcification
- the process of deposition of calcium salts. In the formation of bone
this is a normal condition. In other organs, this could be an abnormal
condition. Calcification of the aortic valve causes narrowing of the
passage (aortic stenosis).
- Cancer
- refers to abnormal cells, which have a tendency to grow uncontrollably
and metastasize or spread to other areas of the body. Cancer can involve
any tissue of the body and can have different forms in one tissue. Cancer
is a group of more than 100 different diseases.
- Carbohydrate
- considered a macronutrient because carbohydrates provide a significant
source of calories (energy) in the diet. Chemically, carbohydrates are
neutral compounds composed of carbon, hydrogen and oxygen. Carbohydrates
come in simple forms known as sugars and complex forms, such as starches
and fiber.
- Carboxylation
- the introduction of a carboxyl group (-COOH) or carbon dioxide into
a compound.
- Carcinogen
- a cancer-causing agent; adjective: carcinogenic.
- Carcinogenesis
- the formation of cancer cells from normal cells.
- Carcinoid syndrome
- the pattern of symptoms exhibited by individuals with carcinoid tumors.
Carcinoid tumors secrete excessive amounts of the neurotransmitter,
serotonin. Symptoms may include flushing, diarrhea, and sometimes wheezing.
- Cardiomyopathy
- literally, disease of the heart muscle that often leads to abnormal
function.
- Cardiovascular
- referring to the heart and blood vessels.
- Cardiovascular diseases
- literally, diseases affecting the heart and blood vessels. The term
has come to encompass a number of conditions that result from atherosclerosis,
including myocardial infarction (heart attack), congestive heart failure,
and stroke.
- Carnitine
- a compound that is required to transport long chain fatty acids across
the inner membrane of the mitochondria, in the form of acyl-carnitine,
where they can be metabolized for energy.
- Carotid arteries
- the left and right common carotid arteries are the principal blood
vessels that supply oxygenated blood to the head and neck. Each has
two main branches, the external and internal carotid artery.
- Cartilage
- a soft, elastic tissue that composes most of the skeleton of vertebrate
embryos and except for a small number of structures is replaced by bone
during ossification in the higher vertebrates. Cartilage cushions joints,
connects muscles with bones, and makes up other parts of the body such
as the larynx (voice box) and the outside portion of the ears.
- Case-control study
- a study, in which exposures of people who have been diagnosed with
a disease (cases) are compared to those of people without the disease
(controls). The results of case-control studies are more likely to be
distorted by bias in the selection of cases and
controls (selection bias) and dietary recall (recall bias) than prospective
cohort studies.
- Case reports
- individual observations based on small numbers of subjects. This type
of research cannot indicate causality but may indicate areas for further
research.
- Catalyze
- increase the speed of a chemical reaction without being changed in
the overall reaction process. See enzyme.
- Catecholamines
- substances with a specific chemical structure (a benzene ring with
two adjacent hydroxyl groups and a side chain of ethylamine) that function
as hormones or neurotransmitters. Examples include epinephrine, norepinephrine,
and dopamine.
- Cataract
- clouding of the lens of the eye. As cataracts progress they can impair
vision.
- Cation
- a positively charged ion.
- Celiac disease
- also known as celiac sprue, celiac disease is an inherited disease
in which the intestinal lining is inflamed in response to the ingestion
of a protein known as gluten. Treatment of celiac disease involves the
avoidance of gluten, which is present in many grains, including wheat,
rye, oats, and barley. Inflammation and atrophy of the lining of the
small intestine leads to impaired nutrient absorption.
- Cell adhesion molecules
- molecules on the outside surfaces of cells that bind to other cells
or to the extracellular matrix (material surrounding cells). Cell adhesion
molecules influence many important functions, including the entry of
immune cells into the arterial wall.
- Cell cycle
- the orderly sequence of stages that a cell passes through between
one cell division (mitosis) and the next. The cell cycle can be divided
into four stages: the M (mitosis) phase, in which nuclear and cytoplasmic
division occurs; the G1 phase or interphase; the S (synthesis) phase,
in which DNA replication occurs; and the G2 phase, a quiescent period
prior to the next M phase.
- Cell membrane
- also called a plasma membrane, the barrier that separates the contents
of a cell from its outside environment and controls what moves in and
out of the cell. A mammalian cell membrane consists of a phospholipid
bilayer with embedded proteins and cholesterol.
- Cell signaling
- communication among individual cells so as to coordinate their behavior
to benefit the organism as a whole. Cell-signaling systems elucidated
in animal cells include cell-surface and intracellular receptor proteins,
GTP-binding proteins, and protein kinases and protein phosphatases (enzymes
that phosphorylate and dephosphorylate proteins).
- Central nervous system (CNS)
- the brain, spinal cord, and spinal nerves.
- Cerebrospinal fluid
- the fluid that bathes the brain and spinal chord.
- Cerebrovascular disease
- disease involving the blood vessels supplying the brain, including
cerebrovascular accident (CVA), also known as a stroke.
- Cervical intraepithelial
neoplasia (CIN)
- a term used to describe abnormal growth of cells on the surface of
the uterine cervix. CIN1 is also known as low grade squamous intraepithelial
lesion (LSIL). CIN2 and CIN3 are also known as high-grade squamous intraepithelial
lesions (HSIL). Although these abnormal cells are not cancerous, they
may progress to cervical cancer.
- Chelate
- the combination of a metal with an organic molecule to form a ring-like
structure known as a chelate. Chelation of a metal may inhibit or enhance
its bioavailability.
- Chemotherapy
- literally, treatment with drugs. Commonly used to describe the systemic
use of drugs to kill cancer cells, as a form of cancer treatment.
- Cholesterol
- a compound that is an integral structural component of cell
membranes and a precursor in the synthesis of steroid
hormones. Dietary cholesterol is obtained from animal sources, but
is also synthesized by the liver. Cholesterol is carried in the blood
by lipoproteins. In atherosclerosis,
cholesterol accumulates in plaques on the walls of some arteries.
- Cholestatic liver disease
- liver disease resulting in the cessation of bile
excretion. Cholestasis may occur in the liver, gallbladder
or bile duct (duct connecting the gall bladder to the small
intestine).
- Cholinergic
- resembling acetylcholine in action, a cholinergic drug for example.
Cholinergic nerve fibers liberate or are activated by the neurotransmitter,
acetylcholine.
- Chorionic
villus sampling (CVS)
- a procedure for obtaining a small sample of tissue from the
placenta (chorionic villi) for the purpose of prenatal diagnosis of
genetic disorders. CVS can be performed between 9 to 12 weeks of pregnancy.
- Chromosome
- a structure in the nucleus of a cell that contains genes. Chromosomes
are composed of DNA and associated proteins. Normal human cells contain
46 chromosomes (22 pairs of autosomes and 2 sex chromosomes)..
- Chronic disease
- an illness lasting a long time. By definition of the U.S. Center for
Health Statistics, a chronic disease is a disease lasting 3 months or
more.
- Chronic obstructive
pulmonary disease (COPD)
- a term that includes emphysema and chronic
bronchitis, two chronic lung diseases that are characterized by
airway obstruction.
- Chylomicrons
- triglyceride-rich lipoproteins that deliver
dietary triglycerides from the intestine
to the tissues immediately after a meal. Chylomicrons release their
triglycerides to tissue through the activity of lipoprotein lipase enzymes
in tissue capillary beds. When they are depleted of most of their triglycerides,
chylomicron remnants are taken up by the liver, where the lipids
and cholesterol that remain are excreted
in bile or incorporated into other lipoproteins..
- Cirrhosis
- a condition characterized by irreversible scarring of the liver, leading
to abnormal liver function. Cirrhosis has a number of different causes,
including chronic alcohol use and viral hepatitis B and C.
- Clinical trial
- an intervention trial generally
used to evaluate the efficacy and/or safety of a treatment or intervention
in human participants.
- Clone
- an exact copy of a DNA segment; produced by recombinant
DNA technology.
- Coagulation
- the process involved in blood clot formation.
- Coenzyme
- a molecule that binds to an enzyme and is essential for its activity,
but is not permanently altered by the reaction. Many coenzymes are derived
from vitamins.
- Cofactor
- a compound that is essential for the activity of an enzyme.
- Cognitive
- an adjective referring to the processes of thinking, learning,
perception, awareness, and judgment.
- Cohort
- a group of people who are followed over time as part of an epidemiological
study.
- Cohort study
- a study that follows a large group of people over a long period of
time, often 10 years or more. In cohort studies, dietary information
is gathered before disease occurs, rather than relying on recall after
disease develops.
- Collagen
- a fibrous protein that is the basis for the structure of skin, tendon,
bone, cartilage and all other connective tissue.
- Collagenous matrix (of bone)
- The organic (nonmineral) structural element of bone. Collagen is a
fibrous protein that provides the organic matrix upon which bone mineralize
crystallizes.
- Colon
- the portion of the large intestine that extends from the end of the
small intestine to the rectum. The colon removes water from digested
food after it has passed through the small intestine and stores the
remaining stool until it can be evacuated.
- Colorectal adenoma
- a polyp or growth in the lining of the colon or rectum. Although they
are not cancerous, colorectal adenomas may develop into colorectal cancer
over time.
- Colorectal cancer
- cancer of the colon (large intestine) or
rectum.
- Colostomy
- the surgical construction of an artificial anus by connecting the
colon to an opening in the abdominal wall
- Concomitant
- accompanying. "Concomitant intake" refers to the intake
of two compounds at the same time.
- Congenital hypothyroidism
- also known as cretinism, congenital hypothyroidism
occurs in two forms, although there is considerable overlap. The neurologic
form is characterized by mental and physical retardation and deafness.
It is the result of maternal iodine deficiency that affects the fetus
before its own thyroid is functional. The myxedematous or hypothyroid
form is characterized by short stature and mental retardation. In addition
to iodine deficiency, the hypothyroid form has been associated with
selenium deficiency and the presence of goitrogens
in the diet that interfere with thyroid hormone
production.
- Congenital malformation
- birth defects.
- Congestive heart failure
(CHF)
- a condition, in which the heart loses the ability to pump blood efficiently
enough to meet the demands of the body. Symptoms may include edema (swelling),
shortness of breath, weakness and exercise intolerance.
- Conjugation
- the formation of a water-soluble derivative of a chemical by its combination
with another compound, such as glutathione, glucuronate, or sulfate.
- Cornea
- the transparent covering of the front of the eye that transmits and
focuses light into the eye.
- Coronary angioplasty
- a procedure used to open an occluded coronary
artery. A flexible hollow catheter is inserted into a large blood
vessel in the groin and advanced to the heart. At the site of the occlusion,
the balloon tip of the catheter is inflated and the occluded coronary
artery is dilated. Coronary angioplasty is also known as percutaneous
transluminal coronary angioplasty or PTCA.
- Coronary artery
- one of the vessels that supply oxygenated blood to the heart muscle
itself. They are called coronary arteries because they encircle the
heart in the form of a crown.
- Coronary artery bypass
graft (CABG)
- a surgical procedure used to create new routes around obstructions
in coronary arteries and restore adequate blood flow to the heart muscle.
- Coronary heart disease (CHD)
- also known as coronary artery disease and coronary disease, coronary
heart disease is the result of atherosclerosis
of the coronary arteries. Atherosclerosis
may result in narrowing or blockage of the coronary arteries and is
the underlying cause of myocardial
infarction (heart attack).
- Corticosteroid
- any of the steroid hormones
made by the cortex (outer layer) of the adrenal
gland. Cortisol is a corticosteroid. A number of medications are
analogs of natural corticosteroid hormones.
- Creatine phosphate
- a high-energy compound found in muscle cells which is used to convert
ADP into ATP by donating phosphate molecules to the ADP. ATP is the
molecule which is converted into ADP with a release of energy that the
body then uses.
- Crohn's disease
- an inflammatory bowel disease that usually affects the lower part
of the small intestine or upper part of the colon, but may affect any
part of the gastrointestinal tract.
- Cross-over trial
- a clinical trial in at least two interventions or treatments are applied
to the same individuals after an appropriate wash-out period. One of
the treatments is often a placebo. In a
randomized cross-over design, interventions are applied in a randomized
order to ensure that the order of treatments did not contribute to the
outcome.
- Cross-sectional study
- a study of a group of people at one point in time to determine whether
an exposure is associated with the occurrence of a disease. Because
the disease outcome and the exposure (e.g., nutrient intake) are measured
at the same time, a cross-sectional study provides a “snapshot” view
of their relationship. Cross-sectional studies cannot provide information
about causality..
- Cystic fibrosis (CF)
- a hereditary disease caused by mutations in the cystic fibrosis transmembrane
conductance regulator (CFTCR) gene. Cystic fibrosis is characterized
by the production of abnormal secretions, leading to the accumulation
of mucus in the lungs, pancreas, and intestine. This build-up of mucus
causes difficulty breathing and recurrent lung infections, as well as
problems with nutrient absorption due to problems in the pancreas and
intestines.
- Cytochrome P450
- a family of Phase I biotransformation enzymes that play an important
role in the metabolism and elimination of drugs, toxins, carcinogens
and endogenous compounds, such as steroid hormones.
- Cytokine
- a protein made by cells that affects the behavior of other cells.
Cytokines act on specific cytokine receptors
in the cells they affect.
- Cytoplasm
- the contents of a cell, excluding the nucleus.
- De novo synthesis
- the formation of an essential molecule from simple precursor molecules.
- Debridement
- the removal of necrotic or infected tissue or foreign material from
a wound.
- Decarboxylation
- a chemical reaction involving the removal of a carboxyl (-COOH) group
from a compound.
- Dementia
- significant impairment of intellectual abilities such as attention,
orientation, memory, judgment or language. By definition, dementia is
not due to major depression or psychosis. Alzheimer’s disease is the
most common cause of dementia in older adults.
- Dental caries
- cavities or holes in the outer two layers of a tooth--the
enamel and the dentin. Dental caries are caused by
bacteria which metabolize carbohydrates
(sugars) to form organic acids which dissolve tooth enamel.
- Depletion-repletion study
- a nutritional study designed to determine the requirement for a specific
nutrient. Generally, subjects are placed on a diet designed to deplete
them of a specific nutrient over time. Once depletion is achieved, gradually
increasing amounts of the nutrient under study are added to the diet
until the individual shows evidence of sufficiency or repletion.
- Dermatitis
- inflammation of the skin. This term is often used to describe a skin
rash.
- DEXA
- dual energy X-ray absorptiometry. A precise instrument that uses the
energy from very small doses of X-rays to determine
bone mineral density (BMD) and to diagnose and follow the treatment
of osteoporosis.
- Diabetes mellitus
- a chronic metabolic disease, characterized by abnormally high blood
glucose (sugar) levels, resulting from the inability of the body to
produce or respond to insulin. Type 1 diabetes mellitus, formerly known
as insulin-dependent or juvenile-onset diabetes, is usually the result
of autoimmune destruction of the insulin secreting beta-cells of the
pancreas. The most common form of diabetes is type 2 diabetes mellitus,
formerly known as noninsulin-dependent or adult onset diabetes, which
develops when the tissues of the body become less sensitive to insulin
secreted by the pancreas. .
- Diabetic ketoacidosis
- a potentially life-threatening condition characterized by ketosis
(elevated levels of ketone bodies in the
blood) and acidosis (increased acidity of the blood). Ketoacidosis occurs
when diabetes is not adequately controlled.
- Dialysis
- a medical procedure to filter waste products from the blood. Dialysis
is needed to perform the work of the kidneys if they can no longer function
effectively. Two types of dialysis are hemodialysis
and peritoneal dialysis.
- Diastolic blood pressure
- the lowest arterial blood pressure during the heart beat cycle, and
the second number in a blood pressure reading (e.g., 120/80).
- Differentiation
- changes in a cell resulting in its specialization for specific functions,
such as those of a nerve cell. In general, differentiation of cells
leads to a decrease in proliferation.
- Diffusion
- a passive process, in which particles in solution move from a region
of higher concentration to one of lower concentration.
- Dimer
- a complex of two molecules, usually proteins. Heterodimers
are complexes of two different molecules, while
homodimers are complexes of two of the same molecule.
- Diuretic
- an agent that increases the formation of urine by the kidneys, resulting
in water loss from the individual using the diuretic.
- Diverticulitis
- inflammation or infection of diverticula in the colon (see diverticulosis
below), characterized by abdominal pain, fever and constipation.
- Diverticulosis
- a condition characterized by the formation of small pouches (diverticula)
in the colon. Although most people with diverticulosis experience no
symptoms, about 15-20% may develop pain or inflammation, known as diverticulitis.
- DNA
- deoxyribonucleic acid; a double-stranded nucleic acid composed of
many nucleotides. The nucleotides in DNA are each composed of a nitrogen
containing base (adenine, guanine, cytosine or thymine), a 5-carbon
sugar (deoxyribose), and a phosphate group. The sequence of bases in
DNA encodes the genetic information required to synthesize proteins.
- Dominant trait
- a trait that is expressed when only one copy of the gene responsible
for the trait is present.
- Double blind
- refers to a study in which neither the investigators administering
the treatment nor the participants know which participants are receiving
the experimental treatment and which are receiving the placebo.
- DRI
- dietary reference intake. Refers to a set of at least four nutrient-based
reference values (RDA, AI, UL,
EAR), each with a specific use in defining recommended
dietary intake levels for individual nutrients in the U.S. The DRIs
are determined by expert panels appointed by the Food and Nutrition
Board of the Institute of Medicine.
- DV
- daily value. Refers to the dietary reference values required as the
basis for declaring nutrient content on all products regulated by the
U.S. Food and Drug Administration (FDA), including nutritional supplements.
The DVs for vitamins and minerals reflect the National Academy of Sciences'
1968 RDAs, and do not reflect the most up to date
Dietary Reference Intakes.
- Dyskinesia
- impaired control of voluntary movement. Dyskinesia is sometimes a
side effect of long-term use of antipsychotic medications.
- EAR
- estimated average requirement; a nutrient intake value that is estimated
to meet the requirement of half of the healthy individuals in
a particular life stage and gender group.
- Echocardiography
- a diagnostic test that uses ultrasound to make images of the heart.
It can be used to assess the health of the valves and chambers of the
heart, as well as to measure cardiac output.
- Ecological study
- an epidemiological study that examines the relationships between exposures
and disease rates in a series of populations (e.g. different countries).
Ecological studies often rely on published statistics, such as food
disappearance data or disease-specific death rates.
- Edema
- swelling; accumulation of excessive fluid in subcutaneous tissues
(beneath the skin).
- Eicosanoids
- chemical messengers derived from 20-carbon polyunsaturated fatty acids,
such as arachidonic acid and eicosapentaenoic acid. Eicosanoids play
critical roles in immune and inflammatory responses.
- Electrocardiogram (ECG)
- a recording of the electrical activity of the heart, used to diagnose
cardiac arrhythmias, myocardial
ischemia and myocardial infarction.
- Electroencephalogram (EEG)
- a recording of the electrical activity of the brain, used to diagnose
neurological conditions such as seizure disorders (epilepsy).
- Electrolytes
- ionized (dissociated into positive and negative ions) salts in the
body fluids. Major electrolytes in the body include sodium, potassium,
magnesium, calcium, chloride, bicarbonate, phosphate.
- Electron
- a stable atomic particle with a negative charge.
- Electron transport chain
- a group of electron carriers in mitochondria
that transport electrons to and from each other in a sequence, in order
to generate ATP.
- Element
- One of the 103 chemical substances that cannot be divided into simpler
substances by chemical means. For example, hydrogen, magnesium, lead,
and uranium are all chemical elements. Trace elements are chemical elements
that are required in very small (trace) amounts in the diet to maintain
health. For example, copper, selenium, and iodine are considered trace
elements.
- Emphysema
- a chronic obstructive pulmonary (lung) disease, characterized by damage
to the small air sacs (alveoli) and difficulty breathing. Damage to
the alveoli decreases their elasticity and results in hyperinflation
of the lungs, which impairs gas exchange. Smoking is the most common
cause of emphysema.
- Enamel
- the hard, white, outermost layer of a tooth.
- Endocrine system
- the glands and parts of glands that secrete hormones
that integrate and control the body's metabolic activity. Endocrine
glands include the pituitary, thyroid, parathyroids, adrenals, pancreas,
ovaries, and testes.
- Endogenous
- arising from within the body. Endogenous synthesis refers to the synthesis
of a compound by the body.
- Endometrium
- the inner lining of the uterus.
- Endothelium-dependent
vasodilation
- arterial vasodilation resulting from the production of nitric oxide
in the vascular endothelium.
- Enterocytes
- cells that line the luminal (inner) surface of the intestine.
- Enzyme
- a biological catalyst. That is, a substance that increases the speed
of a chemical reaction without being changed in the overall process.
Enzymes are vitally important to the regulation of the chemistry of
cells and organisms.
- Epidemiological study
- a study examining disease occurrence in a human population.
- Epididymis
- a system of tubules emerging from the testes, which serves as a storage
site form sperm during their maturation.
- Epilepsy
- also known as seizure disorder. Individuals with epilepsy experience
seizures, which are the result of uncontrolled electrical activity in
the brain. A seizure may cause a physical convulsion, minor physical
signs, thought disturbances, or a combination of symptoms.
- Erythropoietin
- a hormone produced by specialized
cells in the kidneys that stimulates the bone marrow to increase the
production of red blood cells. Recombinant erythropoietin is used to
treat anemia in patients with
end stage renal failure.
- Esophagus
- the portion of the gastrointestinal tract that connects the throat
(pharynx) to the stomach.
- Ester
- the product of a reaction between a carboxylic acid and an alcohol
that involves the elimination of water. For example a cholesterol ester
is the product of a reaction between a fatty acid and cholesterol.
- Estrogen
- hormones that bind to estrogen receptors in the nuclei of cells and
promote the transcription of estrogen-responsive genes. Endogenous estrogens
are steroid hormones produced by body. Exogenous estrogens are synthetic
or natural compounds that have estrogenic activity (i.e., bind the estrogen
receptor and promote estrogen-responsive gene transcription).
- Etiology
- the causes or origin of a disease.
- Excretion
- the elimination of wastes from blood or tissues.
- Extracellular fluid (ECF)
- the volume of body fluid excluding that in cells. ECF includes the
fluid in blood vessels (plasma) and fluid between
cells (interstitial fluid).
- Familial adenomatous
polyposis
- a hereditary syndrome characterized by the formation of many polyps
in the colon and rectum, some of which may develop into
colorectal cancer.
- Fatty acid
- an organic acid molecule consisting of a chain of carbon molecules
and a carboxylic acid (COOH) group. Fatty acids are found in fats, oils,
and as components of a number of essential lipids, such as phospholipids
and triglycerides. Fatty acids can be burned
by the body for energy
- Femoral neck
- a portion of the thighbone (femur). The femoral neck is found near
the hip, at the base of the head of femur, which makes up the ball of
the hip joint. Fractures of the femoral neck
sometimes occur in individuals with osteoporosis.
- Fibrocystic breast condition
(FCC)
- a benign (noncancerous) condition of the breasts, characterized by
lumpiness and discomfort in one one or both breasts.
- Food frequency questionnaire
- a type of dietary assessment in which participants are asked to report
how frequently various foods are consumed over a specified period of
time.
- Forced expiratory volume (FEV1)
- the volume of air that can be expelled during the first second of
a forced expiration. FEV1 is used to assess pulmonary
(lung) function.
- Fortification
- the addition of nutrients to foods to prevent or correct a nutritional
deficiency, to balance the total nutrient profile of food, or to restore
nutrients lost in processing.
- Fracture
- a break in a bone or cartilage, often but not always the result of
trauma.
- Free radical
- a very reactive atom or molecule typically possessing a single unpaired
electron.
- Fructosamine
- describes a group of circulating proteins that have become irreversibly bound to glucose.
Fructosamine assays provide information about blood glucose control 2-3 weeks prior to sample collection.
- Fructose
- a very sweet 6-carbon sugar abundant in plants. Fructose is increasingly
common in sweeteners such as high-fructose corn syrup.
- Gallbladder
- a small sac adjacent to the liver. The gallbladder stores bile, which
is secreted by the liver, and releases it into the small intestine through
the common bile duct.
- Gallstones
- crystals formed by the precipitation of cholesterol or bilirubin in
the gallbladder. Gallstones may be asymptomatic (without symptoms) or
they may result in inflammation and infection of the gallbladder.
- Gastroesophageal
reflux disease (GERD)
- a condition in which stomach contents, including acid, back up (reflux)
into the esophagus, causing inflammation and
damage to the esophagus. GERD can lead to scarring of the esophagus,
and may increase the risk of cancer of the esophagus in some patients.
- Gastrointestinal
- referring to or affecting the digestive tract, which includes the
mouth, phyarynx (throat), esophagus, stomach and intestines.
- Gene
- a region of DNA that controls a specific hereditary characteristic,
usually corresponding to a single protein.
- Gene
expression
- the process by which the information coded in genes (DNA) is converted
to proteins and other cellular structures. Expressed genes include those
that are transcribed to mRNA and translated to protein, as well as those
that are only transcribed to RNA (e.g., ribosomal and transfer RNAs).
- Genome
- all of the genetic information (encoded in DNA)
possessed by an organism.
- Gestation
- the period of time between fertilization and birth. In humans, normal
gestation is usually about 40 weeks.
- Glomerulus (plural glomeruli)
- a tuft of capillaries that makes up part of the filtering unit of
the kidney (nephron).
- Gluconeogenesis
- the production of glucose from non-carbohydrate precursors, such as
amino acids (the building blocks of proteins).
- Glucose
- a 6-carbon sugar which plays a major role in the generation of energy
for living organisms.
- Glucose tolerance
- the ability of the body to maintain normal glucose levels when challenged
with a carbohydrate load (see impaired glucose tolerance
- Glucoside
- a glycoside that contains glucose as its carbohydrate (sugar) moiety
(see glycoside below).
- Glutamate
- an excitatory neurotransmitter. Under certain circumstances glutamate
may become toxic to neurons. Glutamate excitotoxicity appears to play
a role in nerve cell death in some neurodegenerative disorders.
- Glutathione
- a tripeptide consisting of glutamate, cysteine and glyceine. Glutathione
is an endogenous intracellular antioxidant, and is also required for
some phase II biotransformation reactions.
- Glycemic index (GI)
- an index of the blood glucose-raising potential of the carbohydrate
in different foods. The GI is calculated as the area under the blood
glucose curve after a test food is eaten, divided by the corresponding
area after a control food (glucose or white bread) is eaten. The value
is multiplied by 100 to represent a percentage of the control food.
- Glycemic load (GL)
- an index that simultaneously describes the blood glucose-raising potential
of the carbohydrate in a food and the quantity of carbohydrate in a
food. The GL of a food is calculated by multiplying the GI by the amount
of carbohydrate in grams provided by a food and dividing the total by
100.
-
- Glycogen
- a large polymer (repeating units) of glucose molecules, used to store
energy in cells, especially muscle and liver cells.
- Glycoside
- a compound containing a sugar molecule that can be cleaved by hydrolysis
to a sugar and a nonsugar component (aglycone).
- Glycosylated hemoglobin
- glucose-bound hemoglobin. A test for glycosylated hemoglobin measures
the percentage of hemoglobin that is glucose bound. Since glucose remains
bound to hemoglobin for the life of a red blood cell (~120 days), glycosylated
hemoglobin values reflect blood glucose control over the past 4 months.
- Goiter
- enlargement of the thyroid gland. Goiter is one of the earliest and
most visible signs of iodine deficiency. The thyroid enlarges in response
to persistent stimulation by TSH. In mild iodine deficiency, this adaptation
response may be enough to provide the body with sufficient thyroid hormone.
However, more severe cases of iodine deficiency result in hypothyroidism.
Thyroid enlargement may also be caused by factors other than iodine
deficiency, especially in iodine sufficient countries, such as the U.S.
- Goitrogen
- a substance that induces goiter formation by interfering with thyroid
hormone production or utilization.
- Gout
- a condition characterized by abnormally high blood levels of uric
acid (urate). Urate crystals may form in joints, resulting in inflammation
and pain. Urate crystals may also form in the kidney and urinary tract,
resulting in kidney stones. The tendency
to develop elevated blood uric acid levels and gout is often inherited.
- GTP
- guanosine triposphate. A high energy molecule, required for a number
of biochemical reactions, including nucleic
acid and protein synthesis (formation).
- Hartnup's disease
- a genetic disorder resulting in defective absorption of the amino
acid, tryptophan.
- HDL
- high density lipoproteins. HDL transport cholesterol from the tissues
to the liver where it can be eliminated in bile. HDL-cholesterol is
considered good cholesterol, because higher blood levels of HDL-cholesterol
are associated with lower risk of heart disease.
- Heme
- compounds of iron complexed in a characteristic ring structure known
as a porphyrin ring.
- Hemodialysis
- the process of removing blood from an artery, removing waste products
from the blood through dialysis, and returning
it to the body through a vein. Hemodialysis is used to treat end stage
renal failure.
- Hemoglobin
- the oxygen-carrying pigment in red blood cells.
- Hemoglobin A1C
- the main fraction of glycosylated (glucose-bound) hemoglobin. Since
glucose remains bound to hemoglobin for the life of a red blood cell
(~120 days), hemoglobin A1C values reflect blood
glucose control over the past 4 months.
- Hemolysis
- rupture of red blood cells.
- Hemolytic anemia
- Anemia resulting from hemolysis (the rupture
of red blood cells).
- Hemorrhage
- excessive or uncontrolled bleeding.
- Hemorrhagic stroke
- a stroke that occurs when a blood vessel ruptures and bleeds into
the brain.
- Hepatitis
- literally, inflammation of the liver. Hepatitis caused by a virus
is known as viral hepatitis. Other causes of hepatitis include toxic
chemicals and alcohol abuse.
- Hepatocellular carcinoma
- the most common type of primary liver cancer.
- Hereditary spherocytosis
- a hereditary form of anemia characterized by abnormally shaped red
blood cells which are spherical and abnormally fragile. The increased
fragility of these red blood cells leads to hemolytic anemia
(anemia caused by the rupture of red blood cells).
- Heterodimer
- a dimer or complex of two different molecules,
usually proteins.
- Heterozygous
- possessing two different forms (alleles) of
a specific gene.
- HIV
- human immunodeficiency virus. The virus that causes AIDS.
- Homocysteine
- a sulfur-containing amino acid, which is an intermediate in the metabolism
of another sulfur-containing amino acid, methionine. Elevated
homocysteine levels in the blood have been associated with increased
risk of cardiovascular disease.
- Homodimer
- a dimer or complex of two of the same molecule,
usually a protein.
- Homologous
- having the same appearance, structure or evolutionary origin.
- Homozygous
- possessing two identical forms (alleles) of
a specific gene.
- Hormone
- a chemical, released by a gland or a tissue, which affects or regulates
the activity of specific cells or organs. Complex bodily functions,
such as growth and sexual development, are regulated by hormones.
- Hot flushes
- sensations of heat in the skin, particularly the face, neck and chest,
also known as hot flashes. Hot flushes are most often related to declining
estrogen levels during the perimenopause (period surrounding menopause).
- Human papilloma virus (HPV)
- a group of viruses that may cause papillomas (growths or warts) on
the skin or other parts of the body, including the genitals and the
larynx (voice box). Infection with particular strains of HPV is associated
with increased risk of cervical cancer.
- Huntington's disease
- an inherited degenerative disorder of the brain. Its symptoms include
movement disorders and impaired cognitive function. Symptoms of Huntington's
disease, previously known as Huntington's chorea, typically develop
in the fourth decade of life and progressively deteriorate over time.
- Hydrolysis
- cleavage of a chemical bond by the addition of water. In hydrolysis
reactions, a large compound may be broken down into smaller compounds
when a molecule of water is added.
- Hydroxyapatite
- a calcium phosphate salt. Hydroxyapatite is the main mineral component
of bone of bone and teeth, and is what gives them their rigidity.
- Hydroxylation
- a chemical reaction involving the addition of a hydroxyl (-OH) group
to a compound.
- Hyperparathyroidism
- excess secretion of parathyroid hormone by the parathyroid glands
resulting in the disturbance of calcium metabolism. Symptoms may include
increased blood levels of calcium (hypercalcemia), decreased blood levels
of phosphorus, loss of calcium from bone, and kidney stone formation.
- Hypertension
- high blood pressure. Hypertension is defined by the Joint National
Committee on Prevention, Detection, Evaluation and Treatment of High
Blood Pressure as a systolic blood pressure of 140 mm Hg or higher and/or
a diastolic blood pressure of 90 mm Hg or higher.
- Hyperthyroidism
- an excess of thyroid hormone which may result from an overactive thyroid
gland or nodule, or from taking too much thyroid hormone.
- Hypoglycemia
- an abnormally low blood glucose concentration. Symptoms may include
nausea, sweating, weakness, faintness, confusion hallucinations, headache,
loss of consciousness, convulsions, or coma.
- Hypoparathyroidism
- a deficiency of parathyroid hormone, which may be characterized by
low blood calcium levels (hypocalcemia).
- Hypothalamus
- An area at the base of the brain that regulates bodily functions, such
as body temperature, hunger, and thirst.
- Hypothesis
- an educated guess or proposition that is advanced as a basis for further
investigation. A hypothesis must be subjected to an experimental test
to determine its validity.
- Hypothyroidism
- a deficiency of thyroid hormone which is normally made by the thyroid
gland, located in the front of the neck.
- Idiopathic
- of unknown cause.
- Ileostomy
- a surgically created connection between the ileum (small intestine)
and an opening in the abdominal wall (stoma) that allows for the evacuation
of feces when a portion of the bowel has been removed.
- Impaired glucose tolerance
- a metabolic state between normal glucose regulation and overt diabetes.
Impaired glucose tolerance is defined medically as a plasma glucose
concentration between 140 and 199 mg/dL (7.8-11.0 mmol) two hours after
the ingestion of 75 g of glucose during an oral glucose tolerance test.
- Incontinence
- inablility to control the evacuation of urine or feces.
- Induction
- initiation of or increase in the expression of a gene in response
to a physical or chemical stimulus (inducer).
- Inflammation
- a response to injury or infection, characterized by redness, heat,
swelling, and pain. Physiologically, the inflammatory response involves
a complex series of events, leading to the migration of white blood
cells to the inflamed area.
- Insoluble
- not dissolvable. With respect to bioavailability,
certain substances form insoluble complexes that cannot be dissolved
in digestive secretions, and therefore cannot be absorbed by the digestive
tract.
- Insulin
- a peptide hormone secreted by the
beta-cells of the pancreas required for normal
glucose metabolism.
- Insulin resistance
- diminished responsiveness to insulin.
- International normalized
ratio (INR)
- the preferred method for reporting prothrombin time, a measure of
coagulation status that may be used to evaluate the therapeutic efficacy
of anticoagulants, such as warfarin. The INR is a method for standardizing
prothrombin time results so as to minimize variability between laboratories.
- Intervention trial
- an experimental study (usually a clinical
trial) used to test the effect of a treatment or intervention on
a health- or disease-related outcome.
- Intracellular fluid (ICF)
- the volume of fluid inside cells.
- Intermittent claudication
- a condition characterized by leg pain or weakness on walkiing that
diminishes or resolves with rest. It is usually associated with peripheral
arterial disease.
- In vitro
- literally "in glass", referring to a test or research done in the test
tube, outside a living organism.
- In vivo
- "inside a living organism". An in vivo assay evaluates a biological
process occurring inside the body.
- 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.
- Ion channel
- a protein, embedded in a cell membrane that serves as a crossing point
for the regulated transfer of an ion or a group of ions across the membrane.
- Ischemia
- a state of insufficient blood flow to a tissue.
- Ischemic stroke
- a stroke resulting from insufficient blood flow to an area of the
brain, which may occur when a blood vessel supplying the brain becomes
obstructed by a clot.
- Isomers
- compounds that have the same numbers and kinds of atoms but that differ
in the way the atoms are arranged.
- Jaundice
- a yellowish staining of the skin and whites of the eyes due to increased
bilirubin (a bile pigment) levels in the blood.
Jaundice can be an indicator of red blood cells rupturing (hemolysis),
or disease of the liver or gallbladder.
- Ketone bodies
- any of three acidic chemicals (acetate, acetoacetate,
and beta-hydroxybutyrate). Ketone bodies may accumulate in the blood
(ketosis) when the body has inadequate glucose to use for energy, and
must increase the use of fat for fuel. Ketone bodies are acidic, and
very high levels in the blood are toxic and may result in ketoacidosis.
- Kidney stones
- solid masses resulting from the crystallization of minerals and other
compounds found in urine. Common types of kidney stones include those
composed of calcium oxalate, calcium phosphate and urate. Kidney stones
may form in the kidney, ureters or urinary bladder.
- Larynx
- the area of the throat (pharynx) that contains the vocal cords.
- LDL
- low density lipoprotein. LDLs transport cholesterol from the liver
to the tissues of the body. Elevated serum LDL-cholesterol is associated
with increased cardiovascular disease risk.
- Left ventricular hypertrophy
(LVH)
- abnormal thickening of the wall of the left ventricle (lower chamber)
of the heart muscle. The ventricles have muscular walls in order to
pump blood from the heart through the arteries, but LVH occurs when
the ventricle must pump against abnormally high volume or pressure loads.
LVH may accompany congestive heart
failure (CHF).
- Legumes
- members of the large family of plants known as leguminosae. In this
context the term refers to the fruits or seeds of leguminous plants
(e.g., peas and beans) that are used for food.
- Lens
- the transparent structure inside the eye that focuses light rays onto
the retina (the nerve cells at the back of the eye).
- Leukemia
- an acute or chronic form of cancer that involves the blood-forming
organs. Leukemia is characterized by an abnormal increase in the number
of white blood cells in the tissues of the body with or without a corresponding
increase of those in the circulating blood, and is classified according
to the type of white blood cell most prominently involved.
- Leukocytes
- white blood cells. Leukocytes are part of the immune system. Monocytes,
lymphocytes, neutrophils, basophils and eosinophils are different types
of leukocytes.
- Leukotrienes
- cell-signaling molecules involved in inflammation. Lipoxygenases catalyze
the formation of leukotrienes from eicosanoids, such as arachidonic
acid and eicosapentaenoic acid (EPA).
- Lipid peroxidation
- the process by which lipids are oxidatively modified; so named because
lipid hydroperoxides are formed in the process.
- Lipids
- a chemical term for fats. Lipids found in the human body include fatty
acids, phospholipids, triglycerides and cholesterol.
- Lipoic acid
- a cofactor, essential for the oxidation of
alpha-keto acids, such as pyruvate, in metabolism.
- Lipoproteins
- particles composed of lipids and protein that allow for the transport
of lipids through the bloodstream. A lipoprotein particle is composed
of an outer layer of phospholipids, which renders it soluble in water,
and a hydrophobic core that contains triglycerides and cholesterol esters.
Different types of lipoproteins are distinguished by their surface proteins
(apoproteins), their size and the types and amounts of lipids they contain.
- Lipoprotein(a) [Lp(a)]
- a lipoprotein particle in which the protein (apolipoproteinB-100)
is chemically linked to another protein apolipoprotein(a). Increased
blood levels of Lp(a) are associated with an increased risk of cardiovascular
diseases.
- Lumbar spine
- the portion of the spine between the chest (thorax) and the pelvis.
It is commonly referred to as the small of the back.
- Lumen
- the channel within a tube such as a blood vessel or the intestine.
- Lupus
- see systemic lupus erythematosus
(SLE).
- Lymphocytes
- Leukocytes (white blood cells) that play important roles in the immune
system. T lymphocytes (T cells) differentiate into cells that can kill
infected cells or activate other cells in the immune system. B lymphocytes
(B cells) differentiate into cells that produce antibodies.
- Lysosome
- a cellular organelle containing hydrolytic
enzymes specialized for breaking down cellular
debris. Lysosomal enzymes are separated from the rest of the cell by
a lysosomal membrane and function optimally at an acid pH.
- Macrocytic anemia
- low red blood cell count, characterized by the presence in the blood
of larger than normal red blood cells.
- Macrophages
- white blood cells that engulf and degrade pathogens (bacteria) and
cellular debris. Macrophages are activated or transformed monocytes.
- Macula
- a small area of the retina where vision is the sharpest. The macula
is located in the center of the retina and provides central vision.
- Magnetic Resonance Imaging
(MRI)
- a special imaging technique that uses a powerful magnet and a computer
to provide clear images of soft tissues. Tissues that are well-visualized
using MRI include the brain and spinal cord, abdomen, and joints.
- Malabsorption syndrome
- a disease or condition that results in poor absorption of nutrients
from food.
- Malaria
- an infectious disease caused by parasitic microorganisms called plasmodia.
Malaria can be spread among humans through the sting of certain types
of mosquitos (Anopheles) or by a contaminated needle or transfusion.
Malaria is a major health problem in the tropics and subtropics, affecting
over 200 million people world wide.
- Malignant
- cancerous
- Megaloblastic anemia
- low red blood cell count, characterized by the presence in the blood
of large, immature, nucleated cells (megaloblasts) that are forerunners
of red blood cells. Red blood cells, when mature, have no nucleus.
- Melanin
- a dark brown pigment found in the skin.
- Membrane potential
- the electrical potential difference across a membrane. The membrane
potential is a result of the concentration differences between potassium
and sodium across cell membranes which
are maintained by ion pumps. A large proportion of the body's resting
energy expenditure is devoted to maintaining the membrane potential,
which is critical for nerve impulse transmission, muscle contraction,
heart function, and the transport of nutrients and
metabolites in and out of cells.
- Menstruation
- the cyclic loss of blood by a woman, from her uterus (womb) when she
is not pregnant. Menstruation generally occurs every 4 weeks after a
woman has reached sexual maturity and prior to menopause.
- Meta-analysis
- a statistical technique used to combine the results from different
studies to obtain a quantitative estimate of the overall effect of a
particular intervention or exposure on a defined outcome.
- Metabolism
- the sum of the processes (reactions) by which a substance is assimilated
and incorporated into the body or detoxified and excreted from the body.
- Metabolite
- a compound derived from the metabolism of another compound is said
to be a metabolite of that compound.
- Metastasize
- to spread from one part of the body to another. Cancer is said to
metastasize when it spreads from the primary site of origin to a distant
anatomical site.
- Methionine
- a sulfur containing amino acid, required
for protein synthesis and other vital metabolic processes. It can be
obtained through the diet in protein or synthesized from homocysteine.
- Methylation
- a biochemical reaction resulting in the addition of a methyl group
(-CH3) to another molecule.
- Micelle
- an aggregate or cluster of amphipathic molecules in water. Amphipathic
molecules have a polar or hydrophilic end and a nonpolar or hydrophobic
end. In micelles, amphipathic molecules orient with their hydrophobic
ends in the interior and their hydrophilic ends on the exterior surface,
exposed to water.
- Micronutrient
- a nutrient required by the body in small amounts, such as a vitamin
or a mineral.
- Migraine headache
- a type of headache thought to be related to abnormal sensitivity of
blood vessels (arteries) in the brain to various triggers resulting
in rapid changes in the artery size due to spasm (constriction). Other
arteries in the brain and scalp then open (dilate), and throbbing pain
is perceived in the head. The tendency toward migraine appears to involve
serotonin, a neurotransmitter
that can trigger the release of vasoactive substances in the blood vessels.
- Minerals
- nutritionally significant elements. Elements are composed of only
one kind of atom. Minerals are inorganic, i.e., they do not contain
carbon as do vitamins and other organic compounds.
- Mitochondria
- energy-producing structures within cells. Mitochondria possess two
sets of membranes, a smooth continuous outer membrane, and an inner
membrane arranged in folds. Among other critical functions, mitochondria
convert nutrients into energy via the electron
transport chain.
- mm Hg
- millimeters of mercury. The unit of measure for blood pressure.
- Moiety
- a portion of something, such as a functional group of a molecule.
- Mole
- the fundamental unit for measuring chemical compounds (abbreviated
mol). One mole equals the molecular weight of a compound in grams. The
number of molecules in a mole is equal to 6.02 x 1023 (Avogadro's
number).
- Monomer
- a molecule that can be chemically bound as a unit of a polymer.
- Monounsaturated fatty
acid
- a fatty acid with only one double bond between carbon atoms.
- Multifactorial
- refers to diseases or conditions that are the result of interactions
between multiple genetic and environmental factors.
- Multiple sclerosis (MS)
- an autoimmune disorder, in which
the myelin sheaths of nerves in the brain and spinal cord are damaged,
resulting in progressive neurological symptoms.
- Mutation
- a change in a gene, in other words, a change in the sequence of base
pairs in the DNA that makes up a gene. Mutations in a gene may or may
not result in an altered gene product.
- Myelin
- the fatty substance that covers myelinated nerves. Myelin is a layered
tissue surrounding the axons or nerve fibers. This sheath acts as a
conduit in an electrical system, allowing rapid and efficient transmission
of nerve impulses. Myelination refers to the process in which nerves
acquire a myelin sheath.
- Myocardial infarction (MI)
- death (necrosis) of heart muscle tissue due to an interruption in
its blood supply. Commonly known as a heart attack, an MI usually results
from the obstruction of a coronary artery by a clot in people who have
coronary atherosclerosis (heart disease).
- Myocarditis
- an inflammation of the heart muscle.
- Myocytes
- muscle cells.
- Myoglobin
- a heme-containing pigment in muscle cells that binds and stores oxygen.
- Myopathy
- any disease of muscle.
- Necrosis
- unprogrammed cell death, in which cells break open and release their
contents, promoting inflammation. Necrotic cell death may be the result
of injury, infection or infarction.
- Nephropathy
- kidney damage or disease.
- Neural Tube Defect (NTD)
- a birth defect caused by abnormal development of the neural tube,
the structure which gives rise to the central nervous system. Neural
tube defects include anencephaly and spina
bifida.
- Neurodegenerative diseases
- disease resulting from the degeneration or deterioration of nerve
cells (neurons). Alzheimer’s disease and Parkinson’s disease are neurodegenerative
diseases.
- Neurologic
- or neurological; involving nerves or the nervous system (brain, spinal
cord, and all sensory and motor nerves).
- Neuropathy
- nerve damage or disease.
- Neurotoxic
- toxic or damaging to nervous tissue (brain and peripheral nerves).
- Neurotransmitter
- a chemical that is released from a nerve cell and results in the
transmission of an impulse to another nerve cell or organ (e.g., a muscle).
Acetylcholine, dopamine, norepinephrine and serotonin are neurotransmitters.
- Neutrophils
- whitel blood cells that internalize and destroy pathogens, such as
bacteria. Neutrophils also called polymorphonuclear leukocytes because
they are white blood cells with multi-lobed nuclei.
- NIH
- National Institutes of Health. Administered under the US Department
of Health and Human Services (HHS), the NIH are more than 20 separate
institutes and centers devoted to medical research.
- Nitric oxide
- a gaseous signaling molecule synthesized from the amino acid arginine
by enzymes called nitric oxide synthases. In the vascular endothelium,
nitric oxide promotes arterial vasodilation.
- Nucleic acids
- DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid); long polymers of nucleotides.
- Nucleotides
- subunits of nucleic acids. Nucleotides are composed of a nitrogen-containing
base (adenine, guanine, cytosine, uracil or thymine), a 5-carbon sugar
(ribose or deoxyribose), and one or more phosphate groups.
- Nucleus
- a membrane-bound cellular organelle, which contains DNA organized
into chromosomes.
- Observational study
- a study in which no experimental intervention or treatment is applied.
Participants are simply observed over time.
- One-carbon unit
- a biochemical term for functional groups containing only one carbon
in addition to other atoms. One-carbon units transferred by folate coenzymes
include methyl (-CH3), methylene (-CH2-), fomyl
(-CH=O), formimino (-CH=NH), and methenyl (-CH=). Many biosynthetic
reactions involve the addition of a one-carbon unit to a precursor molecule.
- Optimum health
- in addition to freedom from disease, the ability of an individual
to function physically and mentally at his or her best.
- Organelles
- specialized components of cells, such as
mitochondria or lysosomes, so named because
they are analogous to organs.
- Organic
- refers to carbon-containing compounds, generally synthesized by living
organisms.
- Oropharynx
- a term used to describe the mouth and throat.
- Osteoarthritis
- a degenerative joint condition that is characterized by the breakdown
of articular cartilage (cartilage within the joint).
- Osteoblasts
- bone cells that are responsible for the formation of new bone mineral
in the bone remodeling process.
- Osteoclasts
- bone cells that are responsible for the breakdown or resorption of
bone in the bone remodeling process.
- Osteomalacia
- a disease of adults that is characterized by softening of the bones
due to loss of bone mineral. Osteomalacia is characteristic of vitamin
D deficiency in adults, while children with vitamin D deficiency suffer
from rickets.
- Osteoporosis
- a condition of increased bone fragility and susceptibility to bone
fracture due to a loss of bone
mineral density (BMD)
- Oxidant
- reactive oxygen species.
- Oxidation
- a chemical reaction that removes electrons
from an atom or molecule.
- Oxidative stress
- a condition, in which the effects of pro-oxidants
(e.g. free radicals, reactive
oxygen and reactive nitrogen species) exceed the ability of antioxidant
systems to neutralize them.
- Pancreas
- a small organ located behind the stomach and connected to the duodenum
(small intestine). The pancreas synthesizes enzymes that help digest
food in the small intestine and hormones, including insulin, that regulate
blood glucose levels.
- Parathyroid glands
- glands located behind the thyroid gland in the neck. The parathyroid
glands secrete a hormone called parathormone (PTH) that is critical
to calcium and phosphorus metabolism.
- Parkinson's
disease
- a disease of the nervous system caused by degeneration of a part of
the brain called the basal ganglia, and by low production of the neurotransmitter
dopamine. Symptoms include muscle rigidity, tremors, and slow voluntary
movement.
- Pathogen
- disease-causing agent, such as a virus or a bacteria.
- Peptic ulcer disease
- a disease characterized by ulcers or break down of the inner lining
of the stomach or duodenum. Common risk factors for peptic ulcer disease
include the use of nonsteroidal anti-inflammatory drugs (NSAIDs) and
infection with Helicobacter pylori.
- Peptide
- a chain of amino acids. A protein
is made up of one or more peptides.
- Peptide hormones
- hormones that are proteins,
as opposed to steroid hormones,
which are made from cholesterol. Insulin is an
example of a peptide hormone.
- Percutaneous
transluminal coronary angioplasty (PTCA)
- a nonsurgical technique, in which a balloon catheter is inserted into
a peripheral artery and passed into an occluded coronary artery, where
the balloon is inflated to dilate the artery.
- Peripheral neuropathy
- a disease or degenerative state affecting the nerves of the extremities
(arms and legs). Symptoms may include numbness, pain, and muscle weakness.
- Peripheral arterial
disease
- atherosclerosis of the arteries of
the extremities
- Peripheral vascular
disease
- atherosclerosis of the vessels of the extremities, which may result
in insufficient blood flow or pain in the affected limb, particularly
during exercise.
- Peritoneal dialysis
- a procedure, in which a special dialysis
solution is introduced through a tube in the peritoneum.
The dialysis solution pulls wastes and extra fluid from the body, when
the dialysis solution is drained through the same tube. The most common
form is called continuous ambulatory peritoneal dialysis and can be
performed at home without a machine.
- Peritoneum
- a membrane that lines the walls of the abdominal cavity.
- Pernicious anemia
- the end stage of an autoimmune
inflammation of the stomach, resulting in destruction of stomach cells
by one's own antibodies. Progressive
destruction of the cells that line the stomach cause decreased secretion
of acid and enzymes required to release food bound vitamin B-12.
Antibodies to intrinsic factor (IF) bind to IF preventing formation
of the IF-B-12 complex, further inhibiting vitamin B-12 absorption.
- PET scan
- positron emission tomography. A diagnostic imaging technique that
uses a sophisticated camera and computer to produce images of how a
person's body is functioning. A PET scans shows the difference between
healthy and abnormally functioning tissues.
- pH
- a measure of acidity or alkalinity.
- Pharmacokinetics
- the study of the absorption, distribution, metabolism and elimination
of drugs and other compounds.
- Phase I clinical trial
- a clinical trial in a small group of people aimed at determining bioavailability,
optimal dose, safety and early evidence of the efficacy of a new therapy.
- Phase II clinical trial
- a clinical trial designed to investigate the effectiveness of a new
therapy in larger numbers of people and to further evaluate short-term
side effects and safety of the new therapy.
- Pharmacologic dose
- the dose or intake level of a nutrient many times the level associated
with the prevention of deficiency or the maintenance of health.
A pharmacologic dose is generally associated with the treatment of a
disease state and considered to be a dose at least 10 times greater
than that needed to prevent deficiency.
- Phenolic compounds
- a class of chemical compounds consisting of a hydroxyl functional
group (-OH) attached to an aromatic hydrocarbon group. An aromatic hydrocarbon
has a ring structure like that of benzene. Polyphenolic compounds contain
more than one phenolic group.
- Phenylketonuria (PKU)
- an inherited disorder resulting in the inability to process the amino
acid, phenylananine. If not treated, the disorder may result in
mental retardation. Treatment is a diet low in phenylalanine. Newborns
are screened for PKU, in order to determine the need for treatment before
brain damage occurs.
- Phlebotomy
- the removal of blood from a vein. Phlebotomy may be used to obtain
blood for diagnostic tests or to treat certain conditions, for example,
iron overload in hemochromatosis.
- Phospholipids
- lipids in which phosphoric acid as well as
fatty acids are attached to a glycerol backbone. Phospholipids are important
structural components of cell membranes.
- Phosphorylation
- the creation of a phosphate derivative of an organic molecule. This
is usually achieved by transferring a phosphate group (-PO4)
from ATP to another molecule.
- Physiologic dose
- the dose or intake level of a nutrient associated with the prevention
of deficiency or the maintenance of health. A physiologic dose
of a nutrient is not generally greater than that which could be achieved
through a conscientious diet, as opposed to the use of supplements.
- Phytochemicals
- biologically active, non-nutrient compounds synthesized by plants.
- Phytoestrogens
- compounds with estrogenic activity derived
from plants.
- Pigment
- a compound that gives a plant or animal cell color by the selective
absorption of different wavelengths of light.
- Pituitary gland
- a small oval gland located at the base of the brain that secretes
hormones regulating growth and metabolism.
The pituitary gland is divided into two separate glands, the anterior
and posterior pituitary glands, which each secrete different hormones.
- Placebo
- an inert treatment that is given to a control group while the experimental
group is given the active treatment. Placebo-controlled studies are
conducted to make sure that the results are due to the experimental
treatment, rather than another factor associated with participating
in the study.
- Placenta
- the organ that connects the fetus to the mother’s uterus, allowing
for the exchange of oxygen, carbon dioxide, nutrients and waste between
mother and fetus.
- Placental abruption
- premature separation of the placenta from the wall of the uterus.
Abruption is a potentially serious problem both for the mother and baby.
- Plasma
- the liquid portion of blood, in which the cells are suspended. Plasma
is separated from blood cells using a centrifuge. Unlike serum, plasma
retains clotting factors because it is obtained from blood that is not
allowed to clot.
- Platelet
- irregularly shaped cell fragments that assist in blood clotting.
- Pneumonia
- a disease of the lungs, characterized by inflammation and accumulation
of fluid in the lungs. Pneumonia may be caused by infectious agents
(e.g., viruses or bacteria) or by inhalation of certain irritants.
- Polymer
- a large molecule formed by combining many similar smaller molecules
(monomers) in a regular pattern.
- Polymorphism
- a variant form of a gene. Most polymorphisms are harmless and are
part of normal human genetic variation, but some polymorphisms affect
the function of the gene product (protein).
- Polyp
- a benign (non-cancerous) mass of tissue that forms on the inside of
a hollow organ, such as the colon.
- Polyunsaturated fatty
acid
- a fatty acid with more than one double bond between carbons.
- Postprandial
- after eating or after a meal.
- Precursor
- a molecule which is an ingredient, reactant, or intermediate in a
synthetic pathway for a particular product.
- Preeclampsia
- a condition characterized by a sharp rise in blood pressure during
the third trimester of pregnancy. High blood pressure may be accompanied
by edema (swelling) and proteinuria (protein in the urine). In some
cases, untreated preeclampsia can progress to eclampsia, a life-threatening
situation for mother and child.
- Prevalence
- the proportion of a population with a specific disease or condition
at a given point in time.
- Procarcinogen
- a carcinogen precursor that must be modified or metabolized to become
an active carcinogen.
- Prognosis
- predicted outcome based on the course of a disease.
- Proliferation
- rapid cell division.
- Pro-oxidant
- an atom or molecule that promotes oxidation
of another atom or molecule by accepting electrons. Examples of pro-oxidants
include free radicals, reactive
oxygen species (ROS) and reactive
nitrogen species (RNS).
- Prophylaxis
- prevention, often refers to a treatment used to prevent a disease.
- Prospectiv
