10/6/15

cystic fibrosis

The cystic fibrosis - A serious and potentially fatal genetic disorder, characterized by a tendency to develop chronic lung infections combined with an inability to absorb fats and other nutrients from food. The main characteristic feature of cystic fibrosis (CF) is the secretion of sticky, viscous mucus in the nose, throat, airways, and intestines.

CAUSES:
CF is caused by an inherited defect in a gene. The defect is recessive, which means that one faulty gene must be inherited from each parent before any abnormality appears. People with only one defective gene have no symptoms but are “carriers” and can pass the gene on to their children. 209

The defective gene causes a biochemical abnormality in which the faulty movement of ions across cell membranes affects mucus formation. As a result, the mucus-forming glands in several organs do not function properly. Most seriously, the glands in the lining of the bronchial tubes produce thick mucus, which predisposes the person to chronic lung infections.

Another serious malfunction is poor or absent secretion of pancreatic enzymes, which are involved in the breakdown and absorption of fats in the intestine. The sweat glands are also affected and excrete excessive amounts of salt.

SYMPTOMS AND COMPLICATIONS:
The course and severity of CF vary. Typically, a child passes unformed, pale, oily, foul-smelling faeces and may fail to thrive. Often, growth is stunted and the child has recurrent respiratory infections. Without prompt treatment, pneumonia, bronchitis, and bronchiectasis may develop, causing lung damage. Most males and some females are infertile. Excessive salt loss from sweating may lead to heatstroke and collapse.

DIAGNOSIS AND TREATMENT:
Early diagnosis, confirmed by simple sweat and blood tests, improves the outlook for children with CF. Prompt treatment with intensive physiotherapy and antibiotics helps to reduce the severity and frequency of lung infections.

In addition, lung function may be improved by treatment with dornase alfa, a genetically engineered version of a human enzyme, which is administered by nebulizer. Pancreatin and a diet rich in proteins and calories are given to bring about weight gain and encourage more normal faeces. Supervision of the treatment is best carried out from a special centre that is staffed by paediatricians, nurses, and physiotherapists who have particular knowledge of the disease.

OUTLOOK:
The highly specialized treatment now available for people with CF maximizes their chances of a reasonable quality of life. About 9 in 10 children survive into their teens; many live well into their 40s. Progressive respiratory failure is the usual cause of death, but in some cases a heart-lung transplant may be considered.
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cystectomy

cystectomy
The cystectomy - The surgical removal of part or all of the bladder. The procedure is used for treating bladder cancer (see bladder tumours). Radical cystectomy (in which all of the bladder is removed) is followed by the construction of an alternative channel for urine, usually ending in a stoma in the lower abdomen (see urinary diversion).

In men, the prostate gland and seminal vesicles are also removed, usually resulting in impotence.

In women, the uterus, ovaries, and fallopian tubes are removed. After radical cystectomy, the patient has to wear an external pouch to collect urine.
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cyst

The cyst - An abnormal but usually harmless lump or swelling filled with fluid or semisolid material. Cysts occur in body organs or tissues.

There are various types, including sebaceous cysts, dermoid cysts, ovarian cysts, breast cysts, Baker’s cysts, and cysts that form around parasites in diseases such as hydatid disease or amoebiasis. Cysts may need to be removed surgically if they disrupt the function of body tissues.
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cyproterone acetate

The cyproterone acetate -  A drug that blocks the action of androgen hormones. It is used to treat prostate cancer (see prostate, cancer of) and occasionally to reduce male sex drive. Side effects include weight gain and an increased risk of blood clots.
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Cymalon

The Cymalon - A brand name for an over-the-counter preparation containing sodium bicarbonate, sodium carbonate, citric acid, and sodium citrate. This preparation is commonly used to relieve the symptoms of cystitis.
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cyclothymia

The cyclothymia - A personality characteristic typified by marked changes of mood from cheerful, energetic, and sociable to gloomy, listless, and withdrawn. Mood swings may last for days or months and may follow a regular pattern.
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cycloplegia

The cycloplegia - Paralysis of the ciliary muscle of the eye, which makes accommodation difficult. In some circumstances, cycloplegia may be induced by cycloplegic drugs to facilitate eye examinations.
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cyclophosphamide

The cyclophosphamide - An anticancer drug used in the treatment of Hodgkin’s disease and leukaemia. It is also used as an immunosuppressant and to treat connective tissue diseases.
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cyclopenthiazide

The cyclopenthiazide - A thiazide diuretic drug used to reduce oedema associated with heart failure, kidney disorders, cirrhosis of the liver, and to treat hypertension. Side effects of this drug include lethargy, loss of appetite, leg cramps, dizziness, rash, and impotence.
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cyanosis

The cyanosis - A bluish coloration of the skin or mucous membranes caused by an abnormally high level of deoxygenated haemoglobin in the blood. Cyanosis confined to the hands and feet is not serious; it is usually due to slow blood flow, often as a result of exposure to cold.

A blue tinge to the lips and tongue, however, could be caused by a serious heart or lung disorder such as chronic obstructive pulmonary disease or heart failure.
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cyanide

The cyanide - Any of a group of salts of hydrocyanic acid. Most of these substances are extremely poisonous, and their inhalation or ingestion can rapidly lead to breathlessness and paralysis, followed by unconsciousness and death. Certain cyanides are eye irritants and are used in tear gases.
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cuticle

The cuticle - The outermost layer of skin. The term commonly refers to the thin flap of skin at the base of a nail, and also to the outer layer of a hair shaft.
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cutdown

The cutdown - Creation of a small skin incision in order to gain access to a vein, to take blood or to give intravenous fluid. This procedure is sometimes needed when a vein cannot be identified through the skin, in conditions such as shock.
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cusp

The cusp - A tapering point, such as on a tooth. The term also refers to the flaps of the heart valves.
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Cushing's syndrome

The Cushing's syndrome - A hormonal disorder caused by an abnormally high level of corticosteroid hormones in the blood. Cushing’s syndrome is characterized by a reddened, moon-shaped face, wasting of the limbs, thickening of the trunk, and a humped upper back.

Other symptoms include acne; stretch marks on the skin; bruising; osteoporosis (loss of bone density); susceptibility to infection and peptic ulcers; and, in women, increased hairiness. Mental changes frequently also occur, causing depression, insomnia, paranoia, or, euphoria. Oedema, hypertension, and diabetes mellitus may develop. In children, growth may be suppressed.

The excess of hormones is most commonly due to prolonged treatment with corticosteroid drugs. Such cases of Cushing’s syndrome are usually mild. In other cases, high hormone levels are due to overactivity of the adrenal glands because of an adrenal tumour, or due to a pituitary tumour affecting production of ACTH (adrenocortocotrophic hormone), which in turn stimulates the adrenal glands.

Cushing’s syndrome due to corticosteroid drugs usually disappears when the dose of the drug is gradually reduced. In cases of Cushing’s syndrome that are caused by an adrenal gland tumour, the tumour will be removed surgically. If the cause of the disease is a pituitary tumour, it may be removed surgically or shrunk by irradiation and drug treatment. In both of these cases, surgery is followed by hormone replacement therapy.
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Curling's ulcer

The Curling's ulcer - A type of stress ulcer that occurs specifically in people who have suffered extensive skin burns.
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curette

The curette - A spoon-shaped surgical instrument used for scraping away material or tissue from an organ, cavity, or surface.
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curettage, dental

The curettage, dental - The scraping of a cavity or other dental surface with a curette (a narrow, spoonshaped instrument).

Dental curettage is one method used to remove the lining of periodontal pockets and diseased tissue from root surfaces in periodontitis. This enables the healthy underlying tissue to reattach itself to the root surface.
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curettage

The curettage - The use of a surgical instrument called a curette to scrape abnormal tissue, or samples for analysis, from the lining of a body cavity or from the skin.
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cure

The cure - The process of restoration to normal health after an illness. The word “cure” usually means the disappearance of a disease rather than simply a halt in its progress. A treatment that ends an illness may also be called a cure.
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curare

The curare - An extract from the bark and juices of various trees that has been used for centuries by South American Indians as an arrow poison.

Curare kills by producing muscle paralysis. Synthetic compounds that are related to curare are sometimes used to produce paralysis during surgery.
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cupping

The cupping - An ancient procedure in which the practitioner draws blood to the skin surface by applying a heated vessel to the skin. It produces an inflammatory response thought to relieve bronchitis, asthma, and musculoskeletal pains.
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culture

The culture - A growth of bacteria or other microorganisms, cells, or tissues cultivated artificially in the laboratory. Microorganisms are collected from the site of an infection and cultured in order to produce adequate amounts so that tests to identify them can be performed.

Cells from a fetus may be cultured to diagnose disorders prenatally. Healthy cells may be cultured for the study of chromosomes (see chromosome analysis). Some types of tissue, such as skin, may be cultured to produce larger amounts that can then be used for grafting.

Other tissues are cultivated to provide a medium in which viruses can be grown and identified in the laboratory; viruses will only multiply within living cells.
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cuff

The cuff - A body structure that consists of muscle and tendon fibres and encircles a joint. (See also rotator cuff.)

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CT scanning


CT scanning
The CT scanning - A diagnostic technique in which the combined use of a computer and a machine emitting X-rays produces crosssectional images of the body tissues.

A CT (computed tomography) scanner is a machine that is shaped like a doughnut that rotates around the patient’s body. The machine contains one or more X-ray sources and, on the opposite side, some X-ray detectors. Unlike a conventional X-ray image, which shows only a few levels of tissue density, the X-ray detector can register hundreds of levels of density. It sends this information to a computer, which processes the data and shows the results as an image on a monitor. CT images usually show the body as “slices”, in which the different tissues can be seen in detail. In some machines, this information can be used to produce a three-dimensional reconstruction of the area scanned.

CT scanning has revolutionized the diagnosis and treatment of tumours, abscesses, and haemorrhages in the brain, as well as head injuries and strokes. The procedure is also used to locate and show tumours, to investigate a wide range of diseases, and to aid needle biopsy in organs of the trunk.

Newer types of CT scanners use a spiral technique: the scanner rotates around the body as the patient is moved slowly forwards on a bed, causing the X-ray beams to follow a spiral course. Images can be made of hollow organs such as the colon (a procedure known as “virtual colonoscopy”). For some procedures, injected or swallowed contrast media (chemicals that are opaque to X-rays) may be used to make certain tissues more easily visible.

The images produced during CT scanning can be stored digitally or on conventional X-ray film. (For details of the procedure, see Performing a CT scan box, opposite.)
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CS spray

The CS spray - A noxious powder, also known as CS gas or tear gas, that is used in aerosol form as a means of riot control.

CS spray causes severe irritation of the eyes, airways, and skin, and sometimes nausea and vomiting. Its effects are short-lived, usually lasting for only a few minutes.
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cryptosporidiosis

The cryptosporidiosis - A type of diarrhoeal infection caused by protozoa, which may be spread from person to person or be transmitted from domestic animals to people.

The disease causes watery diarrhoea and sometimes fever and abdominal pain. It is most common in children but also occurs in people with AIDS. In most cases, rehydration therapy is the only treatment needed.

In people whose immune system is suppressed, however, the infection may be much more severe. Such people may need to be admitted to hospital for treatment with intravenous fluids and antidiarrhoeal drugs.

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cryptorchidism

The cryptorchidism - A developmental disorder of male infants in which the testes fail to descend normally into the scrotum (see testis, undescended).
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cryptophthalmus

The cryptophthalmus - A birth defect in which the opening between the upper and lower eyelids is absent. (See also Fraser’s syndrome.)
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cryptococcosis

The cryptococcosis - A rare infectious disorder caused by inhaling the fungus CRYPTOCOCCUS NEOFORMANS, which is found especially in soil contaminated with pigeon faeces. The most serious form that the infection can take is meningitis.

Another form of infection causes growths in the lungs, resulting in chest pain and a cough, or on the skin, causing a rash of ulcers. Most cases of cryptococcosis occur in people with reduced immunity, such as those with AIDS.

Cryptococcal meningitis is diagnosed from a sample of spinal fluid. A combination of the antifungal drugs amphotericin B and flucytosine is usually prescribed to treat the infection. Most cases in which only the lungs are infected need no treatment.
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cryotherapy

The cryotherapy - The use of cold or freezing temperatures or substances in treatment. (See also cryosurgery.)
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cryosurgery

The cryosurgery - The use of temperatures below freezing to destroy tissue, or the use of cold during surgical procedures to produce adhesion between an instrument and an area of body tissue.

Cryosurgery causes only minimal scarring. It is used to treat cancerous tumours in sites where heavy scarring can block vital openings, such as in the cervix, the liver, and the intestines. It may be used in eye operations, for example in cataract surgery and treatment for retinal detachment.

It is also commonly used for removing warts, skin tags, some birthmarks, and some skin cancers, and to treat haemorrhoids.
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cryopreservation

The cryopreservation - The preservation of living cells or tissue samples by freezing. The technique is used to store human eggs for in vitro fertilization, sperm for artificial insemination, or plasma and blood obtained from people with rare blood groups.
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cryo

The cryo - A prefix meaning “ice cold”. It is used of medical procedures that involve the use of freezing or low temperatures.
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crying in infants

The crying in infants - A normal response in babies to needs or discomforts, such as hunger or thirst. Most healthy babies stop crying when their needs are attended to.

In a few cases, persistent crying may be due to a physical cause such as intolerance of cow’s milk or an illness (such as an ear or throat infection, or a viral fever).
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crutch palsy

The crutch palsy - Weakness or paralysis of muscles in the wrist, fingers, and thumb in people who walk with a crutch under the armpit.

Crutch palsy is due to pressure on the nerves supplying these muscles. It does not occur if elbow crutches are used.
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crush syndrome

The crush syndrome - Damage to a large amount of muscle (usually as a result of a serious accident), which causes kidney failure. The damaged muscles release proteins into the bloodstream, temporarily impairing kidney function.

As a result, some substances normally excreted in the urine build up to toxic levels in the blood. If left untreated, crush syndrome may be fatal, but dialysis allows the kidneys time to recover.
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cruciate ligament

The cruciate ligament - One of the two ligaments in the knee that pass over each other to form a cross. The ligaments form connections between the femur and tibia inside the knee joint and prevent overbending and overstraightening at the knee.
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crowning

The crowning - The popular name given to the phase in the second stage of labour (see childbirth) when the baby’s head first appears at the mother’s vaginal opening.
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crown–heel length

The crown–heel length -  A routine measurement of the length of a newborn baby, taken from the crown of the head to the heels.
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crown, dental

The crown, dental - An artificial replacement for the crown of a decayed, discoloured, or broken tooth. A crown made from porcelain is usually used on front teeth, but back teeth need the greater strength of a crown made from gold or porcelain fused to metal.

A crown may be fitted by filing the tooth to form a peg and cementing the crown over the top of it. For a badly decayed or weakened tooth, it may be necessary to remove the natural crown, perform root-canal treatment, then fit the artificial crown on to a post that is cemented in the root canal. For details on how crowns are fitted, see the illustrated box below.
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crown


how crowns are fitted
The crown - The name for the top of the head. The word is also used of the visible part of a tooth. (See also crown, dental; crowning.)
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Crouzon's syndrome

The Crouzon's syndrome - An autosomal dominant genetic disorder that causes facial deformities. Affected people have these features: eyes that protrude (see exophthalmos) and are spaced widely apart; a squint; an abnormally tall skull; a large, beaked nose; and an underdeveloped upper jaw, which makes the lower jaw look as if it is protruding.
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croup

The croup - A common disorder in infants and young children, in which narrowing and inflammation of the airways causes hoarseness, stridor (a grunting noise during breathing), and a barking cough.

Croup may be caused by a viral or bacterial infection affecting the larynx, epiglottis, or trachea. Most cases are due to a viral infection and are generally mild. Other causes include diphtheria, allergy, spasm due to insufficient calcium levels in the blood, and inhalation of a foreign body.

Humidifying the air can help to ease breathing. In some cases, corticosteroid drugs administered through a nebulizer, and oxygen, may be prescribed. If the infection is bacterial, it is treated with antibiotic drugs.
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cross matching

The cross matching - A procedure to determine compatibility between the blood of a person who requires a blood transfusion and that of a donor.

Red blood cells from one person are combined with serum (the clear fluid that separates from blood when it clots) from the other. Clumping of red blood cells indicates the presence of antibodies, showing that the blood is not compatible.
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cross eye

The cross eye - A type of strabismus (squint) in which one of the eyes turns inwards relative to the other, or in which both eyes turn inwards towards each other.
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crossbite

The crossbite - A type of malocclusion (an abnormal relationship between the upper and lower teeth) in which some or all of the lower front teeth overlap the upper front teeth. A molar crossbite, in which the upper and lower back teeth overlap, can also occur.
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