Cholesterol

Cholesterol, a complex alcohol constituent of all animal fats and oils. It can be activated to form vitamin D. Cholesterol is one of a group of compounds known as sterols and is related to such other sterols as the sex hormones and the hormones of the adrenal cortex.

A close relationship exists among levels of blood cholesterol in the body, those of other fats or lipids, and the development of atherosclerosis (see Artery). In this disorder, plaques containing cholesterol are deposited on the walls of arteries, particularly those of small and medium size, reducing their inside diameter and the flow of blood. Clotting of blood, such as may occur in the coronary arteries to cause a heart attack, is most likely to develop at places where arterial walls are roughened by such plaques.

Although many foods, particularly dairy products and meat fat, contain cholesterol, the body also synthesizes this sterol from cholesterol-free substances. Nevertheless, investigation indicates that a cholesterol-rich diet causes abnormally high levels of cholesterol and the related fats and lipids in the blood. Evidence strongly indicates that people with such high levels are more likely to develop atherosclerosis and heart attacks than those with lower levels. Also significant is the fact that scientists have identified two forms of cholesterol-carrying proteins in the blood, called high-density and low-density lipoproteins. The low-density form is thought to promote atherosclerosis, whereas the high-density component may retard it.

Persons who have abnormally high levels of cholesterol—especially low-density cholesterol—on a congenital basis can reduce their risk of heart attack by lowering their blood cholesterol. This is done by following a diet low in cholesterol and saturated fats, getting sufficient exercise, and using certain drugs. See Nutrition, Human.

Cesarean Section

Cesarean Section, surgical removal of the fetus through incisions in the abdominal wall and the uterus. This operation has been practiced since ancient times on dead and, probably, dying mothers to save the life of the fetus.

In present-day obstetrics a cesarean section is performed for cases in which the size of the birth canal is too small to allow the fetus to pass. The operation also is used in cases of abnormal developments during delivery, such as hemorrhage or tumors in the mother, failure of the cervix to dilate, fetal distress (lack of oxygen), or difficult positioning of the fetus. See Pregnancy and Childbirth.

Cataract

Cataract (vision), in medicine is an opaque condition of the lens of the eye or of its capsule. Its position behind the pupil readily distinguishes this condition from opacities of the cornea. Cataract may affect the lens alone (lenticular), or the front or back of the capsule of the lens (capsular), or both lens and capsule (capsulolenticular). Cataract is painless and unaccompanied by inflammation. It causes blindness by obstructing passage of light, but the patient can distinguish light from darkness.

Traumatic cataract results from a perforating wound of the capsule of the lens. The entire lens becomes opaque, and a portion usually remains so; but at times, unless inflammation of other portions follows, the cloudiness entirely disappears. Congenital cataract is due to an intrauterine infection, chromosomal disorder, or metabolic disease that causes imperfect development or inflammation. Juvenile cataract may be hereditary. The lens is soft and white in both congenital and juvenile cataracts. Both are treated by “needling,” an operation in which a needlelike knife or a laser beam is used to cut and break up the lens. The injured lens tissue is then absorbed by the body. Juvenile and adult cataracts can also be caused by exposure to radiation and by drugs such as glucocorticoids.

Senile cataract, the most common form, usually occurs in people over 50 years of age and generally involves both eyes. It may also occur at a younger age in people with diabetes mellitus. Beginning in the form of dark streaks extending from the periphery toward the center of the lens, or as spots in any portion, it eventually makes the entire lens opaque. As the fluid of the lens is absorbed, the lens becomes easily separated from its capsule and is considered mature, or “ripe” for operation. Later, if not extracted, the lens undergoes degenerative changes, or liquefies, and the capsule becomes thickened and opaque, making the results of operation less satisfactory. The only method of relieving senile cataract is extraction of the lens. Sight can be restored in most instances by wearing special eyeglasses or contact lenses or by a surgeon implanting an artificial lens in the affected eye.

Carbuncle

Carbuncle, in medicine, localized inflammation of tissue under the skin caused by infection. A carbuncle is usually caused by the bacteria Staphylococcus and is larger and more serious than a boil, which results from an inflammation beginning in an infected hair sac. As the carbuncle develops, the area affected becomes red and swells slightly. The subcutaneous tissue becomes hard, the color darkens, and several heads may develop and discharge pus. Tissue is destroyed and sloughs off, leaving a scar upon healing. Treatment includes the use of antibiotics and antiseptics, the application of hot compresses, and, occasionally, surgery.

Carbamazepine

Carbamazepine or Tegretol is a prescription drug used to treat seizures such as those associated with epilepsy. It also relieves neuralgia, or pain along a sensory nerve, in the jaw, tongue, or throat. The drug is occasionally prescribed for patients recovering from alcohol or cocaine addiction, for migraine headaches, and for depression or other emotional disorders. It works by suppressing impulses along nerve fibers in the brain, making seizures less frequent and less severe. It also prevents the transmission of certain nerve impulses, thereby reducing pain.

Carbamazepine is taken orally and is available in tablet form, usually taken twice a day, or liquid form, usually taken four times a day. Both forms should be taken with meals. Daily dosages for control of seizures range from 800 to 1200 mg, the higher recommended dose for adults and children over the age of 12. For neuralgia, doses of 400 to 800 mg per day are usually effective. The drug is typically prescribed in small doses in the beginning, which are increased daily or weekly until symptoms are relieved. This process may take three months or more. Children six years and older may take this drug, although it is usually prescribed in smaller amounts. The maximum children’s daily dosage is 1000 mg.

A variety of side effects have been associated with carbamazepine. They include muscle or joint pain, abdominal pain, constipation, blurred vision, anemia, fainting, drowsiness, hair loss, headache, dizziness, hallucinations, impotence, itching, breathing problems, low blood pressure, sensitivity to light, and sweating. Side effects that include fever, sore throat, mouth ulcers, bruises, or reddish spots on the skin may indicate a blood disorder, which requires immediate medical treatment.

Patients with a sensitivity to certain antidepressant drugs (such as amitriptyline) or with reduced bone-marrow function should not use carbamazepine. It should be used with caution by patients with drug sensitivities and by those who have glaucoma, or impairment of heart, liver, or kidney function. Pregnant or nursing women should avoid using this drug. Because of the potential for dizziness or drowsiness, patients taking this drug should not drive, operate dangerous machinery, or engage in other risk-related activities. Patients who take carbamazepine to control seizures should not stop taking it abruptly, as severe, continuous seizures may result.

Carbamazepine should not be combined with antidepressants known as MAO inhibitors. It may also interact adversely with lithium, theophylline, doxycycline, haloperidol, as well as calcium channel blockers, oral contraceptives (see Birth Control Pill), and other antiseizure medications.

Brand Names:Tegretol, Atretol

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