D & C: Dilatation and curettage, a minor operation in which the cervix is expanded enough (dilatation) to permit the cervical canal and uterine lining to be scraped with a spoon-shaped instrument called a curette (curettage).

Dactylitis: Inflammation of a digit (either a finger or a toe).

Death rate: The number of deaths in the population divided by the average population (or the population at midyear) is the crude death rate. In 1994, for example, the crude death rate per 1,000 population was 8.8 in the United States, 7.1 in Australia, etc. A death rate can also be tabulated according to age or cause.

Decongestants: Drugs that shrink the swollen membranes in the nose and make it easier to breath. Decongestants can be taken orally or by nasal spray. Decongestant nasal spray should not be used for more than five days without the doctor"s advice, and if so, usually only when accompanied by a nasal steroid. Many decongestant nasal sprays often cause a rebound effect if taken too long. A rebound effect is the worsening of symptoms when a drug is discontinued. This is a result of a tissue dependence on the medication. Decongestants should not be used by patients with high blood pressure (hypertension) unless under doctor’s supervision.

Defect, atrial septal (ASD): A hole in the septum, the wall, between the atria, the upper chambers of the heart. Commonly called an ASD. ASDs are a major class of congenital cardiac malformation.

Defect, enzyme: An abnormality in the protein (enzyme) important in catalyzing a normal biochemical reaction in the body. Disorders result from a deficiency (or functional abnormality) of an enzyme. Archibald Garrod in 1902 was the first to attribute a disease to an enzyme defect: an inborn error of metabolism. Today, newborns are routinely screened for certain enzyme defects such as phenylketonuria (PKU) and galactosemia, an error in the handling (metabolism) of the sugar galactose.

Defect, ventricular septal (VSD): A hole in the interventricular septum, the wall between the ventricles (lower chambers of the heart). Commonly called a VSD. VSDs are a common class of heart deformity present at birth (congenital cardiac malformation).

Deficiency, alpha-1 antitrypsin: An inherited disease with little or no production of an important protein, alpha-1 antitrypsin. The lack of this protein leads to damage of various organs, mainly the lung and liver. The disease may become apparent at a very early age or in adulthood, as shortness of breath or liver-related symptoms (jaundice, fatigue, fluid in the abdomen, mental changes, or gastrointestinal bleeding). There are several options for treatment of the lung disease, including replacement of the missing protein. Treatment of the liver disease is a well-timed liver transplant

Deficiency, calcium: A low blood calcium (hypocalcemia). Hypocalcemia makes the nervous system highly irritable with tetany (spasms of the hands and feet, muscle cramps, abdominal cramps, overly active reflexes, etc.). Chronic calcium deficiency contributes to poor mineralization of bones, soft bones (osteomalacia) and osteoporosis; and, in children, rickets and impaired growth. Food sources of calcium include dairy foods, some leafy green vegetables such as broccoli and collards, canned salmon, clams, oysters, calcium-fortified foods, and tofu. According to the National Academy of Sciences, adequate intake of calcium is 1 gram daily for both men and women. The upper limit for calcium intake is 2.5 grams daily.

Deficiency dermatitis and diarrhea, zinc: A genetic disease called acrodermatitis enteropathica is characterized by the simultaneous occurrence of skin inflammation (dermatitis) and diarrhea. The skin on the cheeks, elbows and knees and tissue about the mouth and anus are inflammed. There is also balding of the scalp, eyebrows and lashes, delayed wound healing and recurrent bacterial and fungal infections due to immune deficiency. The key laboratory finding is an abnormally low blood zinc level reflecting impaired zinc uptake. Oral treatment with zinc is curative.

Deficiency, glucocerebrosidase: Causes Gaucher’s disease (type 1), a progressive genetic disease, due to an enzyme defect. The enzyme, glucocerebrosidase, is needed to break down the chemical glucocerebroside. The enzyme defect in persons with Gaucher’s disease (GD) leads to the accumulation of glucocerebroside in the spleen, liver, and lymph nodes. The most common early sign is enlargement of the spleen (located in the upper left abdomen). Other signs include low red blood cell counts (anemia), a decrease in blood clotting cells (platelets), increased pigmentation of the skin, and a yellow fatty spot on the white of the eye (a pinguecula). Severe bone involvement can lead to pain and collapse of the bone of the hips, shoulders, and spine. The GD gene is on chromosome 1. The disease is a recessive trait. Both parents carry a GD gene and transmit it for their child with the disease. The parents’ risk of a child with the disease is 1 in 4 with each pregnancy. This type of Gaucher’s disease (noncerebral juvenile Gaucher’s disease) is most common in Ashkenazi Jews (of European origin) and is the most common genetic disease among Jews in the United States.

Deficiency, glucose-6-phosphate dehydrogenase (G6PD): Deficiency of G6PD is the commonest disease-causing enzyme defect in humans affecting an estimated 400 million people. The G6PD gene is on the X chromosome. Males with the enzyme deficiency develop anemia due to breakup of their red blood cells when they are exposed to oxidant drugs such as the antimalarial primaquine, the sulfonamide antibiotics or sulfones, naphthalene moth balls, or fava beans.

Deficiency, iron: Deficiency of iron results in anemia because iron is necessary to make hemoglobin, the key molecule in red blood cells responsible for the transport of oxygen. In iron deficiency anemia, the red cells are unusally small (microcytic) and pale (hypochromic). Characteristic features of iron deficiency anemia in children include failure to thrive (grow) and increased infections. The treatment of iron deficiency anemia , whether it be in children or adults, is with iron and iron-containing foods. Food sources of iron include meat, poultry, eggs, vegetables and cereals (especially those fortified with iron). According to the National Academy of Sciences, the Recommended Dietary Allowances of iron are 15 milligrams per day for women and 10 milligrams per day for men.

Deficiency, lactase: Lack of the enzyme lactase resulting in failure to digest lactose in milk (lactose intolerance).

Deficiency, magnesium: Can occur due to inadequate intake or impaired intestinal absorption of magnesium. Low magnesium (hypomagnesemia) is often associated with low calcium (hypocalcemia) and potassium (hypokalemia) levels. Deficiency of magnesium causes increased irritability of the nervous system with tetany (spasms of the hands and feet, muscular twitching and cramps, spasm of the larynx, etc.). According to the National Academy of Sciences, the Recommended Dietary Allowances of magnesium are 420milligrams per day for men and 320 milligrams per day for women. The upperlimit of magnesium as supplements is 350 milligrams daily, in addition to the magnesium from food and water.

Deficiency, protein C: Protein C is a protein in plasma that enters into the cascade of biochemical events leading to the formation of a clot. Deficiency of protein C results in thrombotic (clotting) disease.

Deficiency, selenium: Deficiency of the essential mineral selenium causes Keshan disease, a fatal form of cardiomyopathy (disease of the heart muscle) first observed in Keshan province in China and since found elsewhere. According to the National Academy of Sciences, the Recommended Dietary Allowances of selenium are 70 milligrams per day for men and 55 milligrams per day for women. Food sources of selenium include seafoods, some meats such as kidney and liver, and some grains and seeds.

Deficiency, zinc: Deficiency of zinc is associated with short stature, anemia, increased pigmentation of skin (hyperpigmentation), enlarged liver and spleen (hepatosplenomegaly), impaired gonadal function (hypogonadism), impaired wound healing, and immune deficiency. (For a genetic disorder that impairs zinc uptake, please see Acrodermatitis enteropathica). According to the National Academy of Sciences, the Recommended Dietary Allowances of zinc are 12 milligrams per day for women and 10 milligrams per day for men. Food sources of zinc include meat including liver, eggs, seafood, nuts and cereal.

Deformation: A change from the normal size or shape. Also called deformity. A deformation can be present at birth (congenital) or develop after birth (acquired).

Degenerative arthritis: Also known as osteoarthritis, this type of arthritis is caused by inflammation, breakdown and eventual loss of the cartilage of the joints. Among the over 100 different types of arthritis conditions, osteoarthritis is the most common, affecting usually the hands, feet, spine, and large weight-bearing joints, such as the hips and knees. Also called degenerative joint disease.

Degenerative joint disease: Also known as osteoarthritis, this type of arthritis is caused by inflammation, breakdown and eventual loss of the cartilage of the joints. Among the over 100 different types of arthritis conditions, osteoarthritis is the most common, affecting usually the hands, feet, spine, and large weight-bearing joints, such as the hips and knees. Also called degenerative arthritis.

Dehydration: Excessive loss of body water. Diseases of the gastrointestinal tract may lead to dehydration. One clue to dehydration is a rapid drop in weight. A loss of over 10% (15 pounds in a person weighing 150 pounds) is considered severe. Symptoms include increasing thirst, dry mouth, weakness or lightheadedness (particularly if worsening on standing), or a darkening/decrease in urination are suggestive. Severe dehydration can lead to changes in the body’s chemistry, kidney failure, and become life-threatening. The best way to treat dehydration is to prevent it from occurring. If one suspects fluid loss is excessive, notify a physician. Intravenous or oral fluid replacement may be needed.

Dehydration: Excessive loss of body water.

Delay, developmental: Behind schedule in reaching milestones of early childhood development.

Deletion: Loss of a segment of DNA from a chromosome. An example is the cat-cry (cri du chat) syndrome which is due to loss of part of chromosome 5. A deletion is the opposite of a duplication.

Dementia: Significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning.

Dental braces (orthodontics): The use of devices to move teeth or adjust underlying bone. The ideal age for starting orthodontic treatment is between ages 3 to 12 years. Temporomandibular joint (TMJ) problems can be corrected with splinting or dental braces. Teeth can be moved by removable appliances or by fixed braces. Crowding of teeth can require extraction of teeth. Retainers may be necessary long after dental braces are placed, especially with orthodontic treatment of adults.

Dental impaction: Teeth pressing together. For example, molar teeth (the large teeth in the back of the jaw) can be impacted, cause pain and require pain medication, antibiotics, and surgical removal.

Dental pain (toothache): The most common cause of a toothache is a dental cavity. The second most common is gum disease. Toothache can be caused by a problem that does not originate from a tooth or the jaw.

Dentin: Dentin is the hard tissue of the tooth surrounding the central core of nerves and blood vessels (pulp).

Deoxyribonucleic acid (DNA): The molecule that encodes the genetic information. DNA is a double-stranded molecule that is held together by weak bonds between base pairs of nucleotides to form a double helix. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine ©, and thymine(T). Base pairs form naturally only between A and T and between G and C so the base sequence of each single strand of DNA can be simply deduced from that of its partner strand. The code is in triplets such as ATG. The base sequence of that triplet in the partner strand is therefore TAC.

Department of Energy (DOE). One of the U.S. government agencies contributing to the Human Genome Project.

Depression: Low spirits; dejection. Symptoms of depression include apathy, anorexia, lack of emotional expression (flat affect), social withdrawal and fatigue. Prevalent types of depression are major depression, dysthymia, and bipolar disorder. Some types of depression run in families. The first step to getting appropriate treatment is a complete physical and psychological evaluation to determine whether one, in fact, has a depressive illness.

Depression, bipolar: Formerly called manic- depressive illness. Not nearly as prevalent as other forms of depressive disorders, bipolar disorder involves cycles of depression and elation or mania. Sometimes the mood switches are dramatic and rapid, but most often they are gradual. When in the depressed cycle, you can have any or all of the symptoms of a depressive disorder. When in the manic cycle, any or all symptoms listed under mania may be experienced. Mania often affects thinking, judgment, and social behavior in ways that cause serious problems and embarrassment. For example, unwise business or financial decisions may be made when an individual is in a manic phase. Bipolar disorder is often a chronic recurring condition.

Depression, dysthmia: A less severe type of depression, dysthymia involves long-term chronic symptoms that do not disable, but keep one from functioning at "full steam" or from feeling good. Sometimes people with dysthymia also experience major depressive episodes.

Depression, major: Major depression is manifested by a combination of symptoms (see Depression, symptoms of) that interfere with the ability to work, sleep, eat, and enjoy once pleasurable activities. These disabling episodes of depression can occur once, twice, or several times in a lifetime.

Dermatitis: Inflammation of the skin.

Dermatologic: Having to do with the skin.

Dermatologist: A doctor who specializes in the diagnosis and treatment of skin problems.

Dermatome: (1) A localized area of skin that is has its sensation via a single nerve from a single nerve root of the spinal cord. Shingles (herpes zoster) typically affects one or several isolated dermatomes. (2) A dermatome is also a cutting instrument used for skin grafting or slicing thin pieces of skin.

Dermatomyositis: Dermatomyositis is a chronic inflammatory disease of muscle which is associated with patches of slightly raised reddish or scaly rash. The rash can be on the bridge of the nose, around the eyes, or on sun-exposed areas of the neck and chest. Classically, however, it is over the knuckles. (see polymyositis).

Dermatopathy: Any disease of the skin. Synonymous with dermopathy.

Dermatophytic onychomycosis: Ringworm of the nail, the most common fungus infection of the nails (onychomycosis). Onychomycosis makes the nails look white and opaque, thickened, and brittle. Older women (perhaps because estrogen deficiency may increase the risk of infection). and men and women with diabetes or disease of the small blood vessels (peripheral vacscular disease) are at increased risk. Artificial nails (acrylic or "wraps") increase the risk because when an artificial nail is applied, the nail surface is usually abraded with an emery board damaging it, emery boards can carry infection, and. water can collect under the nail creating a moist, warm environment for fungal growth.Alternative names include tinea unguium.

Dermis: The lower or inner layer of the two main layers of cells that make up the skin.

Dermopathy: Any disease of the skin. Synonymous with dermatopathy.

Desensitization, allergy: Stimulation of the immune system with gradually increasing doses of the substances to which a person is allergic, the aim being to modify or stop the allergy "war" (by reducing the strength of the IgE and its effect on the mast cells). This form of treatment is very effective for allergies to pollen, mites, cats, and especially stinging insects (eg, bees, hornets, yellowjackets, wasps, velvet ants, fire ants). Allergy immunotherapy usually takes 6 months to a year to become effective and shots (injections) are usually required for 3-5 years.

Designer estrogen: An engineered drug that possesses some, but not all, of the actions of estrogen. Designer estrogens are selective estrogen-receptor modulators (SERMs). For example, raloxifene (trade name Evista) is classified as a SERM because it prevents bone loss (like estrogen) and lowers serum cholesterol (like estrogen) but (unlike estrogen) does not stimulate the endometrial lining of the uterus.

Development: The process of growth and differentiation.

Developmental delay: Behind schedule in reaching milestones of early childhood development.

Device, assistive: Any device that is designed, made, and/or adapted to assist a person to perform a particular task. For examples, canes, crutches, walkers, wheel chairs, and shower chairs are all assistive devices. Device, intrauterine contraceptive (IUD): A device inserted into the uterus (womb) to prevent conception (pregnancy). The IUD can be a coil, loop, triangle, or T in shape made of plastic or metal.

Dextro-: From the Latin dexter meaning on the right side. For example, a molecule that shows dextrorotation is turning or twisting to the right. The opposition of dextro- is levo- (from the Latin laevus meaning on the left side) so the opposite of dextrorotation is levorotation.

Dextrocardia: The heart is reversed and is in the right side of the chest rather than in its normal location on the left. This is a true anatomic reversal. With dextrocardia, for example, the apex (tip) of the heart points to the right rather than (as is normal) to the left. Dextrocardia occurs in an abnormal condition present at birth (congenital) called Kartagener’s syndrome.

Dextroposition: Move to the right.

Dextroposition of the heart: The heart is displaced to the right (from its usual location in the left chest). There is no anatomic alteration in the heart itself, just in its location. Dextroposition occurs when the contents of the left side of the chest shove the heart to the right or when the contents of the right chest are reduced (for example, by collapse of the right lung) and the heart moves toward the sparsely occupied space on the right.

Diabetes and fiber: Soluble fibers (oat bran, apples, citrus, pears, peas/beans, psyllium, etc.) slow down the digestion of carbohydrates (sugars), which results in better glucose metabolism. Some patients with the adult-onset diabetes may actually be successfully treated with a high-fiber diet alone, and those on insulin, can often reduce their insulin requirements by adhering to a high-fiber diet.

Diabetes mellitus: A chronic condition associated with abnormally high levels of sugar (glucose) in the blood.. Absence or insufficient production of insulin (which is produced by the pancreas and lowers blood glucose) causes diabetes. The two types of diabetes are referred to as insulin dependent (type I) and non-insulin dependent (type II). Symptoms of diabetes include increased urine output and appetite as well as fatigue. Diabetes mellitus is diagnosed by blood sugar (glucose) testing. The major complications of diabetes mellitus include dangerously elevated blood sugar, abnormally low blood sugar due to diabetes medications, and disease of the blood vessels which can damage the eye, kidneys, nerves, and heart. Treatment depends on the type of the diabetes.

Diabetes, type 1: Insulin dependent diabetes or juvenile diabetes.

Diabetes, type 2: Non-insulin dependent diabetes, adult-onset diabetes or insulin-resistant diabetes.

Diagnosis: The nature of a disease.

Dialysis: The process of cleansing the blood by passing it through a special machine. Dialysis is necessary when the kidneys are not able to filter the blood. Dialysis allows patients with kidney failure a chance to live productive lives. There are two types of dialysis: hemodialysis and peritoneal dialysis. Each type of dialysis has advantages and disadvantages. Patients can often choose the type of long term dialysis that best matches their needs.

Dialysis, peritoneal: Technique that uses the patient’s own body tissues inside of the belly (abdominal cavity) to act as a filter. The intestines lie in the abdominal cavity, the space between the abdominal wall and the spine. A plastic tube called a "dialysis catheter" is placed through the abdominal wall into the abdominal cavity. A special fluid is then flushed into the abdominal cavity and washes around the intestines. The intestinal walls act as a filter between this fluid and the blood stream. By using different types of solutions, waste products and excess water can be removed from the body through this process.

Diaper rash: Also called "diaper dermatitis," a diaper rash is a skin inflammatory reaction localized to the area usually covered by the diaper. It can have many causes including infections (yeast, bacterial or viral), friction irritation, chemical allergies (perfumes, soaps), sweat and plugging of sweat glands.

Diaphragm: The muscle that separates the chest (thoracic) cavity from the abdomen. Contraction of the diaphragm muscle helps to expand the lungs when breathing air inward.

Diaphragmatic hernia: Passage of a loop of bowel through the diaphragm muscle. This type of hernia occurs as the bowel from the abdomen "herniates" upward through the diaphragm into the chest (thoracic) cavity.

Diarrhea: Unusually liquid bowel movements.

Diarrhea, antibiotic-induced: A bacterium called Clostridium difficile (C.difficile), one of the most common causes of infection of the large bowel (colon). Patients taking antibiotics are at particular risk of becoming infected with C. difficile. Antibiotics disrupt the normal bacteria of the bowel, allowing C. difficile bacteria (and other bacteria) to become established and overgrow the colon. Many persons infected with C. difficile bacteria have no symptoms but can become carriers of the bacteria and infect others. In other people, a toxin produced by C. difficile causes diarrhea, abdominal pain, severe inflammation of the colon (colitis), fever, an elevated white blood count, vomiting and dehydration. In severely affected patients, the inner lining of the colon becomes severely inflamed (a condition called pseudomembranous colitis). Rarely, the walls of the colon wear away and holes develop (colon perforation), which can lead to a life-threatening infection of the abdomen.

Diathermy: The use of heat to destroy abnormal cells. Also called cauterization or electrodiathermy.

Dicentric: An abnormal chromosome with two centromeres as opposed to the normal one entromere.

Diethylstilbestrol: A drug that was once widely prescribed to prevent miscarriage. Women whose mothers were given diethylstilbestrol (DES) during pregnancy to prevent miscarriage are at increased risk for developing cancer of the cervix.

Differential diagnosis: The process of weighing the probability of one disease versus that of other diseases possibly accounting for a patient's symptoms.

Differentiation: The process of change during development that leads to the progressive diversity in structure and function of cells.

Diffuse idiopathic skeletal hyperostosis (DISH) : A form of degenerative arthritis characteristically associated with flowing calcification along the sides of the vertebrae of the spine and commonly with inflammation (tendinitis) and calcification of the tendons at their attachments points to bone. Because areas of the spine and tendons can become inflamed, antiinflammatory medications (NSAIDs), such ibuprofen, can be helpful in both relieving pain and inflammation. Also called Forestier’s disease.

Digestive system: The organs that are responsible for getting food into and out of the body and for making use of food to keep the body healthy. These include the mouth, esophagus, stomach, liver, gallbladder, pancreas, small intestine, colon, and rectum.

Digital rectal exam: An exam to detect rectal cancer. The doctor inserts a lubricated, gloved finger into the rectum and feels for abnormal areas. It is also an important screening test for the detection of prostate abnormalities, including cancer.

DiGeorge syndrome (DGS): This disorder is characterized by (1) low blood calcium levels (hypocalcemia) due to underdevelopment (hypoplasia) of the parathyroid glands needed to control calcium; (2) underdevelopment (hypoplasia) of the thymus, an organ behind the breastbone in which lymphocytes mature and multiply; and (3) defects involving the outflow tracts from the heart. Most cases of DGS are due to a very small deletion (microdeletion) in chromosome band 22q11.2. A small number of cases have defects in other chromosomes, notably 10p13. Named after the American pediatric endocrinologist Angelo DiGeorge. Other names for DGS include hypoplasia of the thymus and parathyroids and the third and fourth pharyngeal pouch syndrome.

Digit, supernumerary: An extra finger or toe.

Dilatation and curettage: A minor operation in which the cervix is expanded enough (dilatation) to permit the cervical canal and uterine lining to be scraped with a spoon-shaped instrument called a curette (curettage) This procedure also is called D and C.

Dilate: To stretch or enlarge.

Dilator: A device used to stretch or enlarge an opening. Patients with scarring of the muscular tube through which food passes from the throat to the stomach (esophagus) can require a dilator procedure in order to open the esophagus for adequate passage of food and fluids.

Diphtheria: An acute infectious disease that typically strikes the upper respiratory tract including the throat. Diphtheria can be deadly. It is one of the diseases that the DTP (Diphtheria-Tetanus-Pertussis) and DTaP (Diphtheria-Tetanus-acellular Pertussis) vaccines are designed to prevent.

Diploid: The number of chromosomes in most cells of the body. This number is 46 in humans. It is naturally twice the haploid number of 23 chromosomes contained in human eggs (ova) and sperm.

Diplopia: The condition whereby a single object appears as two objects. Also called "double vision."

Directives, advance medical: Advance directives preserve the person’s right to accept or reject a course of medical treatment even after that person becomes mentally or physically incapacitated to the point of being unable to communicate those wishes. There ared two basic types of advance directives: (1) a living will, in which the person outlines specific treatment guidelines that are to be followed by health care providers; (2) a health care proxy (also called a power of attorney for health-care decision-making) in which the person designates a trusted individual to make medical decisions in the event that he or she becomes too incapacitated to make such decisions. Advance directive requirements vary greatly from one jurisdiction to another and should therefore be drawn up in consultation with an attorney who is familiar with the laws of the particular jurisdiction. (This entry is based upon material from the National MS Society).

Disaster Supplies Kit: You and your family can cope best by preparing for disaster before it strikes. One way to prepare is by assembling a Disaster Supplies Kit. Once disaster hits, you won’t have time to shop or search for supplies. But if you’ve gathered supplies in advance, your family can endure an evacuation or home confinement. For useful information, see the MedicineNet site on YOUR FAMILY DISASTER SUPPLIES KIT.

Disease: Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.

Disease, Addison’s: Long-term underfunction of the outer portion of the adrenal gland. In medical terms, chronic insufficiency of the adrenal cortex. This may be due to a number of different insults to the adrenal including physical trauma, hemorrhage, and tuberculosis of the adrenal, and destruction of the cells in the pituitary gland that secrete ACTH (adrenocorticotropic hormone) which normally drives the adrenal. Addison’s disease is characterized by bronzing of the skin, anemia, weakness, and low blood pressure. The U.S. President J.F. Kennedy is said to have had Addison’s disease. Named after the British physician Thomas Addison (1793-1860).

Disease, adult celiac: This condition results from an immune (allergic) reaction to gluten, a protein found in wheat and related grains and present in many foods that we eat. Sprue causes impaired absorption and digestion of nutrients through the small intestine. Symptoms include requent diarrhea and weight loss. A skin condition called dermatitis herpetiformis can be associated with celiac sprue. The most accurate diagnostic test for sprue is a biopsy of the involved small bowel. Treatment is to avoid gluten in the diet. Medications are used for refractory (stubborn) sprue. Known under a number of other names, including celiac sprue.

Disease, Alzheimer’s: A progressive degenerative disease of the brain that leads to dementia. On a cellular level, Alzheimer’s is characterized by unusual helical protein filaments in nerve cells (neurons) of the brain. These odd twisted filaments are called neurofibrillary tangles. On a functional level, there is degeneration of the cortical regions, especially the frontal and temporal lobes, of the brain. The U.S. President Ronald Reagan is said to have Alzheimer’s disease. Named after the German neurologist Alois Alzheimer (1864-1915).

Disease, bipolar: A type of depressive disease, formerly called manic-depressive illness. Not nearly as prevalent as other forms of depressive disorders. Bipolar disorder involves alternating cycles of depression and elation or mania. Sometimes the mood switches are dramatic and rapid, but most often they are gradual. Mania often affects thinking, judgment, and social behavior in ways that cause serious problems and embarrassment. For example, unwise business or financial decisions may be made when an individual is in a manic phase. Bipolar disorder is often a chronic recurring condition.

Disease, Brill-Zinsser: Recrudescence of epidemic typhus years after the initial attack. The agent that causes epidemic typhus (Rickettsia prowazekii) remains viable for many years and then when host defenses are down, it is reactivated causing recurrent typhus. The disease is named for the physician Nathan Brill and the great bacteriologist Hans Zinsser.

Disease, central core, of muscle (CCD): One of the conditions that produces ‘floppy baby’ syndrome. CCD causes hypotonia (floppiness) in the newborn baby, slowly progressive muscle weakness, and muscle cramps after exercise. Muscle biopsy shows a key diagnostic finding (absent mitochondria in the center of many type I muscle fibers). CCD is inherited as a dominant trait. The CCD gene is on chromosome 19 (and involves ryanodine receptor-1).

Disease, congenital heart: A birth defect of the heart or great blood vessels (like the aorta).

Disease, Conor and Bruch’s: African tick typhus, one of the tick-borne rickettsial diseases of the eastern hemisphere, similar to Rocky Mountain spotted fever, but less severe, with fever, a small ulcer (tache noire) at the site of the tick bite, swollen glands nearby (satellite lymphadenopathy), and a red raised (maculopapular) rash. Also called boutonneuse and fièvre boutonneuse.

Disease, Creutzfeldt-Jakob (CJD): A dementing disease of the brain. It is believed due to an unconventional (not a bacteria or virus), transmissible agent called a prion. Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression. CJD is classified as a spongiform encephalopathy. Most cases occur randomly (sporadically), but inherited forms exist. There is neither treatment nor cure for CJD. Other names for CJD include Creutzfeldt-Jakob syndrome, Jakob-Creutzfeldt disease, and spastic pseuodoparalysis.

Disease, Crohn’s: A chronic inflammatory disease of the intestine. Named after Burrill Crohn who described the disease in 1932. It usually affects persons in their teens or early twenties. It tends to be a chronic, recurrent condition withperiods of remission and exacerbation. In the early stages, there are small scattered shallow crater-like areas (erosions) called apthous ulcers in the inner surface of the bowel. With time, deeper and larger ulcers develop, causing scarring and stiffness of the bowel. The bowel becomes increasingly narrowed, leading to obstruction. Deep ulcers can puncture holes in the bowel wall, leading to infection in the abdominal cavity (peritonitis)and in adjacent organs. When only the large intestine (colon) is involved, the condition is called Crohn’s colitis. When only the small intestine is involved, the condition is called Crohn’s enteritis. When only the end of the small intestine (the terminal ileum) is involved, it is termed terminal ileitis.When both the small intestine and the large intestine are involved, the condition is called Crohn’s enterocolitis (or ileocolitis). Abdominal pain, diarrhea, vomiting, fever, and weight loss can be symptoms. Crohn’s disease can be associated with reddish tender skin nodules, and inflammation of the joints, spine, eyes, and liver. Diagnosis is by barium enema, barium x-ray of the small bowel, and colonoscopy. Treatment includes medications for inflammation, immune suppression, antibiotics, orsurgery. (The disease is also called granulomatous enteritis or regionalenteritis).

Disease, degenerative joint: Also known as osteoarthritis, this type of arthritis is caused by inflammation, breakdown and eventual loss of the cartilage of the joints. Among the over 100 different types of arthritis conditions, osteoarthritis is the most common, affecting usually the hands, feet, spine, and large weight-bearing joints, such as the hips and knees. Also called degenerative arthritis.

Disease, fifth (erythema infectiosum): In the pre-vaccination era, it was frequently the "fifth disease" that a child would develop. It is caused by a virus known as parvovirus B 19. Symptoms include low-grade fever, fatigue, a "slapped cheeks rash," and a rash over the whole body. While the illness is not serious in children, 80% of adults have joint aches and pains (arthritis) which may become long-term with stiffness in the morning, redness and swelling of the same joints on both sides of the body (a "symmetrical" arthritis), most commonly involving the knees, fingers, and wrists. Pregnant women (who have not previously had the illness) should avoid contact with patients who have fifth disease. The fifth disease virus can infect the fetus prior to birth. And, while no birth defects have been reported as a result of fifth disease, it can cause the death of the unborn fetus. The risk of fetal death is 5-10% if the mother becomes infected.

Disease, Fong: The nail-patella syndrome. This condition is sometimes called Fong disease for the physician who in 1946 discovered it in a patient on whom he performed intravenous pyelography while investigating hypertension and albuminuria related to pregnancy. On X-ray Dr. Fong saw the ‘iliac horns’ (symmetrical bilateral central posterior iliac processes) which are now known to be a characteristic feature of nail-patella syndrome.

Disease, Forestier’s: A form of degenerative arthritis characteristically associated with flowing calcification along the sides of the vertebrae of the spine and commonly with inflammation (tendinitis) and calcification of the tendons at their attachments points to bone. Because areas of the spine and tendons can become inflamed, antiinflammatory medications (NSAIDs), such ibuprofen, can be helpful in both relieving pain and inflammation. Also called diffuse idiopathic skeletal hyperostosis (DISH).

Disease, Gaucher’s type 1: A progressive genetic disease caused by a defect in an enzyme. The enzyme, called glucocerebrosidase, is needed to break down the chemical glucocerebroside. The enzyme defect in persons with Gaucher’s disease (GD) leads to the accumulation of glucocerebroside in the spleen, liver, and lymph nodes. The most common early sign is enlargement of the spleen (located in the upper left abdomen). Other signs include low red blood cell counts (anemia), a decrease in blood clotting cells (platelets), increased pigmentation of the skin, and a yellow fatty spot on the white of the eye (a pinguecula). Severe bone involvement can lead to pain and collapse of the bone of the hips, shoulders, and spine. The GD gene is on chromosome 1. The disease is a recessive trait. Both parents carry a GD gene and transmit it for their child with the disease. The parents’ risk of a child with the disease is 1 in 4 with each pregnancy. This type of Gaucher’s disease (noncerebral juvenile Gaucher’s disease) is most common in Ashkenazi Jews (of European origin) and is the most common genetic disease among Jews in the United States.

Disease, graft-versus-host: A reaction of donated bone marrow against a patient’s own tissue. Also called GVHD.

Disease, Graves’: The most common cause of hyperthyroidism (too much thyroid hormone), Graves’ disease is due to a generalized (diffuse) overactivity (toxic) of the whole enlarged thyroid gland (goiter); it is also commonly known as diffuse toxic goiter. There are three components to Graves’ disease: hyperthyroidism, protrusion of the eyes (ophthalmopathy), and skin lesions (dermopathy). Ophthalmopathy can cause sensitivity to light and a feeling of "sand in the eyes." With further protrusion of the eyes, double vision and vision loss may occur. The ophthalmopathy tends to worsen with smoking. Dermopathy of Graves’ disease is a rare, painless, reddish lumpy skin rash that occurs on the front of the leg. Graves’ disease can run in families. Factors that can trigger Graves’ disease include stress, smoking, radiation to the neck, medications (such as interleukin-2 and interferon-alpha), and infectious organisms such as viruses. Graves’ disease can be diagnosed by a typical thyroid scan (diffuse increase uptake), the characteristic triad of ophthalmopathy, dermopathy, and hyperthyroidism, or blood testing for TSI (Thyroid Stimulating Immunoglobulin) level which is abnormally high.

Disease, gum: Inflammation of the soft tissue (gingiva) and abnormal loss of bone that surrounds the teeth and holds them in place. Gum disease is caused by toxins secreted by bacteria in "plaque" that accumulate over time along the gum line. This plaque is a mixture of food, saliva, and bacteria. Early symptoms of gum disease include gum bleeding without pain. Pain is a symptom of more advanced gum disease as the loss of bone around the teeth leads to the formation of gum pockets. Bacteria in these pockets cause gum infection, swelling, pain, and further bone destruction. Advanced gum disease can cause loss of otherwise healthy teeth.

Disease, hemolytic, of the newborn: Abnormal breakup of red blood cells in the fetus or newborn.

Disease, Hirschsprung’s: Absence of nerves (ganglia) in the bowel wall starting in the anus extending up a variable distance with enlargement of the bowel above that point. Hirschsprung’s disease is the commonest cause of lower intestinal obstruction in the newborn and, later, one of the causes of chronic constipation. Also called congenital aganglionic megacolon.

Disease, His: Named for the Swiss physician Wilhelm His, Jr. (who also described the bundle of His in the heart), this is a louse-borne disease first recognized in the trenches of World War I (and so called trench fever), again a major problem in the military in World War II, seen endemically in Mexico, N. Africa, E, Europe, and elsewhere. The cause, Rochalimaea quintana, is an unusual rickettsia that multiplies in the gut of the body louse. Transmission to people can occur by rubbing infected louse feces into abraded (scuffed) skin or conjunctiva (whites of the eyes). Onset of symptoms is sudden, with high fever, headache, back and leg pain and a fleeting rash. Recovery takes a month or more. Relapses are common. Also called Wolhynia fever, shin bone fever, quintan fever, five-day fever, Meuse fever, His-Werner disease, Werner-His disease.

Disease, His-Werner: Named for the Swiss physician Wilhelm His, Jr. (who also described the bundle of His in the heart) and the German physician Heinrich Werner (who did not describe Werner’s syndrome). See Disease, His.

Disease, Hodgkin’s (adult): A type of lymphoma (cancer of the lymphatic system). The most common symptom is painless swelling of the lymph nodes in the neck, underarm, or groin. Hodgkin’s disease is diagnosed when abnormal tissue is detected by a pathologist after a biopsy of an enlarged lymph node. Treatment usually includes radiation therapy or chemotherapy. Regular follow-up examinations are important after treatment. Patients treated for Hodgkin’s disease have an increased risk of developing other types of cancer later in life, especially leukemia.

Disease, Hodgkin’s (Hodgkin’s lymphoma): A disease of the lymph nodes named after the English physician Thomas Hodgkin (1798-1866) who discovered it. ("Perfecting the World" is an excellent biography of Dr. Hodgkin by A. M. and E. H. Kass).

Disease, Huntington’s: An hereditary disorder with mental and physical deterioration leading to death. Although characterized as an "adult-onset" disease (as is usually the case), we have seen children with full-blown Huntington’s disease.

Disease, Jakob-Creutzfeldt: A transmissible degenerative brain disorder technically termed spongiform encephalopathy. Eating "mad cow" meat or squirrel brain can lead to Jakob-Creuzfeldt-like disease. Better known as Creutzfeldt-Jakob disease (CJD). A dementing disease of the brain, believed due to an unconventional, transmissible agent (a prion). Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression. CJD is classified as a spongiform encephalopathy. Most cases occur randomly (sporadically), but inherited forms exist. There is neither treatment nor cure for CJD. Other names for CJD include Creutzfeldt-Jakob syndrome, Jakob’s disease, and spastic pseuodoparalysis.

Disease, Jakob’s: Better known as Creutzfeldt-Jakob disease (CJD), a dementing disease of the brain. It is believed due to an unconventional, transmissible agent (a prion). Symptoms of CJD include forgetfulness, nervousness, jerky trembling hand movements, unsteady gait, muscle spasms, chronic dementia, balance disorder, and loss of facial expression. CJD is classified as a spongiform encephalopathy. Most cases occur randomly (sporadically), but inherited forms exist. There is neither treatment nor cure for CJD. Other names for CJD include Creutzfeldt-Jakob syndrome, Jakob-Creutzfeldt disease, and spastic pseuodoparalysis.

Disease, Kawasaki’s: A syndrome of unknown origin, mainly affecting young children, causing fever, reddening of the eyes (conjunctivitis), lips and mucous membranes of the mouth, ulcerative gum disease (gingivitis), swollen glands in the neck (cervical lymphadenopathy), and a rash that is raised and bright red (maculoerythematous) in a glove-and-sock fashion over the skin of the hands and feet which becomes hard, swollen (edematous), and peels off. Also called mucocutaneous lymph node syndrome.

Disease, Keshan: Condition caused by deficiency of the essential mineral selenium. Keshan disease is a potentially fatal form of cardiomyopathy (disease of the heart muscle). It was first observed in Keshan province in China and since has been found elsewhere (including New Zealand and Finland) in areas where the selenium level in the soil is low.

Disease, kissing: Infectious mononucleosis ("mono"), a very common illness caused by the Epstein-Barr virus (EBV). By the time most people reach adulthood, an antibody against EBV can be detected in their blood meaning they have been infected with EBV. The illness is less severe in young children. The infection can be spread by saliva. Hence, the name: the kissing disease. The incubation period for "mono" is 4 to 8 weeks. Symptoms include fever, fatigue, sore throat, and swollen lymph glands. "Mono" can cause liver inflammation (hepatitis) and spleen enlargement. Vigorous contact sports should be avoided to prevent spleen rupture.

Disease, Legg: See Disease, Legg-Perthes.

Disease, Legg-Calve-Perthes: See Disease, Legg-Perthes.

Disease, Legg-Perthes: A hip disorder in children due to interruption of the blood supply to the head of the femur (the ball in the ball-and-sockethip joint). Also called Legg disease and Legg-Calve-Perthes disease.

Disease, Legionaire’s: A disease (first identified at the 1976 American Legion convention) due to bacteria (Legionella) found in plumbing, shower heads and water-storage tanks. Outbreaks of Legionella pneumonia have been attributed to evaporative condensors and cooling towers. Legionaire’s disease causes a cough, often non-productive, with fevers and a general sense of feeling unwell. Blood testing for antibodies to the bacteria and sputum analysis can aid in the diagnosis of Legionaire’s disease.

Disease, lipid storage: A series of disorders due to inborn errors in lipid metabolism resulting in the abnormal accumulation of lipids in the wrong places (Examples include Gaucher, Fabry and Niemann-Pick diseases and metachromatic leukodystrophy).

Disease, manic-depressive: See Manic-depression.

Disease, maple syrup urine (MSUD): Hereditary disease due to deficiency of an enzyme involved in amino acid metabolism, characterized by urine that smells like maple syrup.

Disease, mitochondrial: Mutations (changes) in the mitochondrial chromosome are responsible for a number of disorders including an eye disease (Leber’s hereditary optic atrophy), a type of epilepsy (called MERRF which stands for Myoclonus Epilepsy with Ragged Red Fibers), and a cause of dementia (called MELAS for Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like episodes). All mitochondrial diseases were entirely enigmatic before it was discovered that they were due to mutations not in regular chromosomes but the mitochondrial chromosome.

Disease, ovarian, polycystic: See Disease, polycystic ovarian.

Disease, polycystic ovarian (PCO): An hormonal problem that causes women to have a variety of symptoms including irregular or no periods, acne, obesity and excessive hair growth. Women with PCO are at a higher risk for uterine cancer (endometrial cancer), diabetes, high blood pressure, and heart disease. With proper treatment, risks can be minimized. PCO is also known as Stein-Leventhal syndrome.

Diseases, polygenic: Genetic disorders that are caused by the combined action of more than one gene. Examples of polygenic conditions include hypertension, coronary heart disease, diabetes, and peptic ulcers. Because such disorders depend on the simultaneous presence of several genes, they are not inherited as simply as single-gene diseases.

Disease, Ritter: This is the scalded skin syndrome, a potentially serious side effect of infection with the Staph (Staphylococcus) bacteria that produces a specific protein which loosens the "cement" holding the various layers of the skin together. This allows blister formation and sloughing of the top layer of skin. If it occurs over large body regions it can be deadly (just like a large surface area of the body having been burned). It is necessary to treat scalded skin syndrome with intravenous antibiotics and to protect the skin from allowing dehydration to occur if large areas peel off. The disease occurs predominantly in children under 5 years of age. It is known formally as Staphyloccoccal scalded skin syndrome.

Disease, sixth: A viral disease of infants and young children with sudden onset of high fever which lasts several days and then suddenly subsides leaving in its wake a fine red rash. The causative agent is herpesvirus type 6 so the disease is known as Sixth Disease. Also known as Exanthem subitum (sudden rash), Pseudorubella, Roseola, Roseola infantilis, and Roseola infantum.

Disease, Stein-Leventhal: See Disease, polycystic ovarian.

Disease, Still’s: Also known as systemic-onset juvenile rheumatoid arthritis and systemic-onset juvenile chronic arthritis. Still’s disease presents with systemic (bodywide) illness including high intermittent fever, a salmon-colored skin rash, swollen lymph glands, enlargement of the liver and spleen, and inflammation of the lungs (pleuritis) and around the heart (pericarditis). The arthritis may not be immediately apparent but it persists after the systemic symptoms are gone. Disease, Still’s, adult-onset: Although Still’s disease was first described in children, it is known to occur in adults.

Disorders, myeloproliferative: Tumors of certain bone marrow cells including those that give rise to red cells, granulocytes, and platelets. As opposed to the lymphoproliferative disorders.

Disease, Paget’s: A condition of unknown cause in which the bone formation is out of synchrony with normal bone remodeling.

Disease, Parkinson’s: An abnormal condition of the nervous system caused by degeneration of an area of the brain called the basal ganglia. The disease results in rigidity of the muscles, slow body movement and tremor. Parkinson’s disease is also called "paralysis agitans" and "shaking palsy."

Disease, Parry’s: Toxic multinodular goiter, a condition in which the thyroid gland contains multiple lumps (nodules) that are overactive and produce excess thyroid hormones. This condition is also known as Plummer’s disease.

Disease, Plummer’s: Toxic multinodular goiter, a condition in which the thyroid gland contains multiple lumps (nodules) that are overactive and produce excess thyroid hormones. This condition is also known as Parry’s disease.

Disease, pelvic inflammatory (PID): Despite its seeming lack of gender, this term is applied to women only. PID refers exclusively to ascending infection of the female genital tract above the cervix.

Disease, phytanic acid storage (Refsum’s disease): A genetic disorder of the fatty acid phytanic acid which accumulates and causes a number of progressive problems including polyneuritis (inflammation of numerous nerves), diminishing vision (due to retinitis pigmentosa), and wobbliness (ataxia) caused by damage to the cerebellar portion of the brain (cerebellar ataxia).

Disease, Pick’s: A form of dementia characterized by a slowly progressive deterioration of social skills and changes in personality leading to impairment of intellect, memory, and language.

Disease, polycystic kidney: Genetic (inherited) disorders characterized by the development of innumerable cysts in the kidneys filled with fluid that replace much of the mass of the kidneys and reduce kidney function leading to kidney failure.

Disease, polycystic ovarian: A hormonal problem that causes women to have a variety of symptoms including irregular or no periods, acne, obesity and excessive hair growth. Also known as Stein-Leventhal syndrome.

Disease, Quincke’s: This is angioneurotic edema (or angioedema), a form of localized swelling of the deeper layers of the skin and fatty tissues beneath the skin. Hereditary angioneurotic edema (or hereditary angioedema) is a genetic form of angioedema. Persons with it are born lacking an inhibitor protein (called C1 esterase inhibitor) that normally prevents activation of a cascade of proteins leading to the swelling of angioedema. Patients can develop recurrent attacks of swollen tissues, pain in the abdomen, and swelling of the voice box (larynx) which can compromise breathing. The diagnosis is suspected with a history of recurrent angioedema. It is confirmed by finding abnormally low levels of C1 esterase inhibitor in the blood. Treatment options include antihistamines and male steroids (androgens) that can also prevent the recurrent attacks.

Disease, Refsum’s: A genetic disorder of the fatty acid phytanic acid which accumulates and causes a number of progressive problems including polyneuritis (inflammation of numerous nerves), diminishing vision (due to retinitis pigmentosa), and wobbliness (ataxia) caused by damage to the cerebellar portion of the brain (cerebellar ataxia).

Disease, Tsutsugamushi: Scrub typhus, a mite-borne infectious disease caused by a microorganism, Rickettsia tsutsugamushi, characteristically with fever, headache, a raised (macular) rash, swollen glands (lymphadenopathy) and a dark crusted ulcer (called an eschar or tache noire) at the site of the chigger (mite larva) bite. This disease occurs in the area bounded by Japan, India, and Australia. Known also as mite-borne typhus and tropical typhus.

Diseases, rickettsial: The infectious diseases caused by the rickettsiae fall into 4 groups:(1) typhus: epidemic typhus, Brill-Zinsser disease, murine (endemic) typhus, and scrub typhus; (2) spotted fever—Rocky Mountain spotted fever, Eastern tick-borne rickettsioses, and rickettsialpox; (3) Q fever; and (4) trench fever.

Diseases, single-gene: Hereditary disorders caused by a change (mutation) in a single gene. There are thousands of single-gene diseases including achondroplastic dwarfism, Huntington disease, cystic fibrosis, sickle cell disease, Duchenne muscular dystrophy, and hemophilia. Single-gene diseases typically describe classic simple Mendelian patterns of inheritance (as autosomal dominant, autosomal recessive, and X-linked traits) by comparison with polygenic diseases.

Disease, von Recklinghausen’s: Hereditary disorder characterized by cafe-au-lait (coffee-with-milk spots on the skin and a tendency to develop nerve tumors) also known as neurofibromatosis.

Disease, Werner-His: Named for the German physician Heinrich Werner (who did not describe Werner’s syndrome) and the Swiss physician Wilhelm His, Jr. (who did describe the bundle of His in the heart), this is a louse-borne disease first recognized in the trenches of World War I (and so called trench fever), again a major problem in the military in World War II, seen endemically in Mexico, N. Africa, E, Europe, and elsewhere. The cause, Rochalimaea quintana, is an unusual rickettsia that multiplies in the gut of the body louse. Transmission to people can occur by rubbing infected louse feces into abraded (scuffed) skin or conjunctiva (whites of the eyes). Onset of symptoms is sudden, with high fever, headache, back and leg pain and a fleeting rash.

Recovery takes a month or more. Relapses are common. Also called Wolhynia fever, shin bone fever, quintan fever, five-day fever, Meuse fever, His-Werner disease.

DISH: Acronym for Diffuse Idiopathic Skeletal Hyperostosis, a form of degenerative arthritis characteristically associated with flowing calcification along the sides of the vertebrae of the spine and, commonly, inflammation (tendinitis) and calcification of the tendons at their attachments points to bone. Because areas of the spine and tendons can become inflamed, antiinflammatory medications (NSAIDs), such ibuprofen, can be helpful in both relieving pain and inflammation. Also called Forestier’s disease.

Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.

Diverticula: The plural of diverticulum. As a person ages, pressure within the large intestine (colon) causes pockets of tissue (sacs) that push out from the colon walls. A small bulging sac pushing outward from the colon wall is a diverticulum. Diverticula can occur throughout the colon but are most common near the end of the left side of the colon, the sigmoid colon.

Diverticulitis: Inflammation of diverticula (small bulging sacs pushing outward from the colon wall). Can be diagnosed with barium x-rays or with sigmoidoscopy or colonoscopy.

Diverticulitis, bleeding from: Diverticular bleeding typically occurs intermittently over several days. Colonoscopy is usually performed to confirm the diagnosis and exclude bleeding from other causes. Thermal probes cannot be employed to stop active diverticular bleeding. Therefore, surgical removal of the bleeding diverticula is necessary for those with persistent bleeding.

Diverticulitis, treatment of acute: Antibiotics are usually needed. Oral antibiotics are sufficient when symptoms are mild. Liquid or low fiber foods are advised during acute diverticulitis attacks. In severe diverticulitis with high fever and pain, patients are hospitalized and given intravenous antibiotics. Surgery is needed for persistent bowel obstruction or abscesses not responding to antibiotics.

Diverticulosis: A small bulging sac pushing outward from the colon wall is called a diverticulum. (Two or more such sacs are diverticula). Diverticula can occur throughout the colon. The condition of having these diverticula in the colon constitutes diverticulosis. associated with inflammation and infection, the condition is called diverticulitis. While most patients with diverticulosis have few or no symptoms. diverticulosis symptoms can include abdominal cramping, constipation, diarrhea, bloating.

Diverticulosis/diverticulitis and fiber: High fiber diets help delay the progression of diverticulosis and, at least, reduce the bouts of diverticulitis.

Diverticulum: A small bulging sac pushing outward from the colon wall is a diverticulum. As a person ages, pressure within the large intestine (colon) causes pockets of tissue (sacs) that push out from the colon walls. The plural is diverticula. Diverticula can occur throughout the colon but are most common near the end of the left side of the colon, the sigmoid colon.

Dizygotic twins: Dizygotic twins are siblings who have shared a common uterine environment. They are due to fertilization of two different ova by different sperm. Dizygotic twins are also called fraternal twins.

Dizziness: Feelings such as lightheadedness, giddiness, depersonalization (the feeling that one is outside ones body), a sense of turning, spinning or rocking. Sometimes a sensation inside the head and other times related to problems with balance.

Dizziness, anxiety as a cause of: One cause of dizziness is overbreathing (hyperventilation) due to anxiety. The overbreathing also causes lightheadedness, a sense of unsteadiness and tingling around the mouth and fingertips. Relief can be gotten by breathing in and out of a paper bag (to increase the level of carbon dioxide in the blood).

Dizziness, pre-syncopal: Syncope is fainting. Pre-syncope is before fainting, whedn one is about to faint. Some symptoms of dizziness such as wooziness, feeling about to black out, and tunnel vision may be pre-syncopal and are due to insufficient blood flow to the brain. These symptoms are typically worse when standing, improve with lying down and may be experienced by healthy individuals who rise quickly from a chair, often after a meal, and have a few seconds of disorientation.

DNA (deoxyribonucleic acid): The molecule that encodes the genetic information. DNA is a double-stranded molecule that is held together by weak bonds between base pairs of nucleotides to form a double helix. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine ©, and thymine(T). Base pairs form naturally only between A and T and between G and C so the base sequence of each single strand of DNA can be simply deduced from that of its partner strand. The code is in triplets such as ATG. The base sequence of that triplet in the partner strand is therefore TAC.

DNA cloning: The use of DNA manipulation procedures to produce multiple copies of a single gene or segment of DNA.

DNA molecules, recombinant: A combination of DNA molecules of different origin that are joined using recombinant DNA technology.

DNA, nongenetic: Through the marvellous medium of the Internet, we have discovered that DNA need not refer to deoxyribonucleic acid. Specifically, in an e-mail entitled " A day in the life of a specialist registrar" from Glascow, Scotland we read that in gynaecology outpatient clinic, the specialist registrar (resident in the U.S.) at "12:10 Sorted out the DNA’s (did not attends)." We in the U. S. might say the "no-show" when a patient does not present for his/her appointment.

DNA polymerase: Enzyme that catalyzes (speeds) the polymerization of DNA. DNA polymerase uses preexisting nucleic acid templates and assembles the DNA from deoxyribonucleotides.

DNA repair: The cell has a series of special enzymes to repair mutations (changes) in the DNA and restore the DNA to its original state.

DNA repair gene: A gene engaged in DNA repair. When a DNA repair gene is altered, mutations pile up throughout the DNA.

DNA repair pathway: The sequence of steps in the repair of DNA. Each step is governed by an enzyme.

DNA, repetitive: DNA sequences that are repeated in the genome.

DNA replication: A wondrous complex process whereby the ("parent") strands of DNA in the double helix are separated and each one is copied to produce a new ("daughter") strand. This process is said to be "semi-conservative" since one of each parent strand is conserved and remains intact after replication has taken place.

DNA, satellite: DNA that contains many tandem (not inverted) repeats of a short basic repeating unit. Satellite DNA is located at very specific spots in the genome (on chromosomes 1, 9, 16 and the Y chromosome, the tiny short arms of chromosomes 13-15 and 21 and 22, and near the centromeres of chromosomes).

DNA sequence: The precise ordering of the bases (A,T,G,C) from which the DNA is composed.

DNA technology, recombinant: A series of procedures used to join together (recombine) DNA segments. A recombinant DNA molecule is constructed (recombined) from segments from 2 or more different DNA molecules. Under certain conditions, a recombinant DNA molecule can enter a cell and replicate there, autonomously (on its own) or