Gonorrhea

Gonorrhea, infectious sexually transmitted infection of humans, which primarily involves the mucous membranes of the urogenital tract. Characterized by a discharge of pus, it is caused by the gonococcus bacterium, Neisseria gonorrhoeae. The incubation period is two to seven days.

SYMPTOMS AND DIAGNOSIS

Gonorrhea is much more obvious in males, who develop an acute discharge of pus from the urethra. Scant at the start, it becomes progressively thicker and heavier and causes frequent urination, often with a burning sensation. Should the prostate become infected, the passage of urine is partly obstructed. In females the infection occurs in the urethra, the vagina, or the cervix. Although discharge and irritation of the vaginal mucous membranes may be severe, more often few or no early symptoms appear.

Gonorrhea can be diagnosed by examining discharge from the penis or vagina for the presence of bacteria. A urine test can also detect the presence of bacteria and it is a noninvasive way to check people who are not exhibiting symptoms. Treatment in the early stages is usually effective. If the disease is untreated in the male, the early symptoms may subside but the infection may spread to the testicles, causing sterility. In the untreated female the infection usually spreads from the cervix into the uterus and fallopian tubes, causing pelvic inflammatory disease (see Gynecology). Severe pain may occur, or the infection may linger with few or no symptoms, gradually damaging the tubes and rendering the woman sterile. In both sexes the gonococcus may enter the bloodstream, resulting in arthritis, heart inflammation, or other diseases. Gonorrhea in pregnant women may be transmitted to the infant during birth and may, if untreated, cause a serious eye infection.

TREATMENT

Antibiotics are commonly used against gonorrhea, although over the years an increasing number of antibiotic-resistant strains of the gonorrhea bacteria have developed, causing a rise in the incidence of the disease in the 1990s. Still effective are antibiotics that are administered in a single dose, including ceftriaxone, cefixime, ciprofloxacin, and ofloxacin.

Glaucoma

Glaucoma, family of eye diseases characterized by increased pressure within the eye and resulting loss of vision. Although the vision loss caused by glaucoma is irreversible, medication or surgery can usually control the pressure within the eye and slow or halt the progression of the disease. If glaucoma is diagnosed in its early stages, it can be treated effectively, and vision can usually be preserved.

Glaucoma occurs in two main varieties, known as chronic simple and acute glaucoma. In chronic simple glaucoma, pressure within the eye rises gradually, and vision loss progresses over a period of years. In acute glaucoma, the pressure inside the eye rises suddenly and immediate medical treatment is necessary to preserve vision. Acute glaucoma is also known as narrow-angle or angle-closure glaucoma, because the angle between the cornea (the transparent layer of tissue at the front of the eye) and the iris (the colored part of the eye) becomes smaller than normal. Chronic simple glaucoma is also known as open-angle glaucoma because the angle between the cornea and iris remains normal. This article focuses on chronic simple glaucoma, which accounts for 95 percent of all cases of glaucoma.

SYMPTOMS AND DIAGNOSIS

In its early stages, glaucoma is symptomless. The gradual increase of pressure inside the eye does not cause any pain or discomfort. As the disease progresses, however, vision begins to deteriorate. The deterioration usually begins with the peripheral vision—sight at the outer edges of the visual field. If glaucoma is left untreated, the field of vision continues to shrink until a person becomes blind.

Glaucoma can be detected before vision loss occurs by a tonometry test, which is a simple, painless part of a routine eye exam. An instrument called a tonometer blows a puff of air into the eye to measure the pressure inside the eye. Some tonometers measure pressure by means of a small plastic prism that is pressed lightly against the surface of the eye. Tests to measure peripheral vision help detect vision loss due to glaucoma. Finally, an instrument called an ophthalmoscope permits examination of the inside of the eye to detect damage to the optic nerve (see Ophthalmology).

TREATMENT

Most cases of glaucoma can be controlled with medication in the form of eyedrops or pills. These medications reduce the pressure inside the eye either by decreasing the amount of aqueous humor produced or by increasing the rate at which the fluid drains from the eye.

When the pressure inside the eye cannot be controlled by medication, surgery may be necessary. In laser surgery, a high-energy laser beam is aimed at the eye to help stretch the trabecular meshwork and make it easier for fluid to flow out of the eye. Sometimes patients who already have had laser surgery develop increased pressure inside the eye again. At that point, conventional surgery is often performed to create a new channel through which fluid can leave the eye. A valve may be surgically implanted in the eye to help control the pressure.

Gene Therapy

Gene Therapy, experimental medical treatment that manipulates a gene or genes within cells in order to produce proteins that change the function of those cells. Gene therapy originated in efforts to treat and cure some of the more than 9,000 known genetic disorders, most of which lack an effective therapy.

The original goal of gene therapy was to substitute a healthy gene for a defective one, or to repair a faulty gene, thereby eliminating symptoms of disease. But researchers have moved beyond inherited genetic disorders to treat other kinds of diseases. Cancer begins in genes and may be caused by an inherited defect or a mutation (permanent alteration to a gene) that causes a cell to malfunction. AIDS is caused by a virus that disrupts the genetic material of immune cells. Other new gene therapy projects are targeted at conditions such as heart disease, diabetes mellitus, arthritis, and Alzheimer's disease, all of which involve genetic susceptibility to illness. Gene therapists hope to reduce or eliminate this susceptibility. Eventually, gene therapy might help older people to regain strength in withered muscles and density in thinned bones, and to increase pumping power in their aging hearts. Some researchers predict that in the distant future the technology could be used to eliminate genetic defects from families or even to produce “designer babies” with more muscle strength, higher intelligence, sweeter dispositions, or whatever traits parents desire.

Gastritis

Gastritis, acute or chronic inflammation of the mucosal lining of the stomach. The ailment was first described in 1833 by the American military surgeon William Beaumont, who was able to study the mucosa of a man who had suffered a gunshot wound in the abdomen. The wound healed with an opening in the stomach wall, through which Beaumont was able to observe the patient's digestive process. In gastritis the inflammation may be marked by the erosion of surface cells of the mucosa, formation of granular nodules, and hemorrhage. In chronic gastritis, there is a growth of fibrous tissue on the lining. Weight loss and delayed emptying of the contents of the stomach may accompany the disease. Gastritis may be caused by excessive consumption of alcohol, abnormal secretion of hydrochloric acid in the gastric juices, and various infections ranging from syphilis and tuberculosis to fungus. Psychological stress may also be involved in the development of gastritis.

Gangrene

Gangrene, mass death or necrosis of individual cells or tissues of a living organism. The immediate physiological cause of gangrene is blockage of arterial blood supply. Among the symptoms of gangrene are loss of sensation and function. The affected part, usually a limb, becomes cold, turns progressively darker in color, and finally undergoes decomposition. Gangrene may take two forms, dry gangrene or moist gangrene.

Dry, or chronic, gangrene occurs when the arteries are blocked gradually and the tissues are bloodless. It may be a result of arteriosclerosis (see Artery). It may also follow frostbite, injury, or the vascular collapse that often accompanies diabetes.

If the dead, bloodless tissue becomes infected by the anaerobic bacterium Clostridium, the condition is called moist, or acute, gangrene. It is also known as gas gangrene because of its putrid-smelling gaseous discharge. The victim's temperature rises sharply, and he or she suffers great pain, acute anemia, and prostration. Moist gangrene may follow contamination of a wound with dirt or other infected matter. It once occurred frequently with war wounds and still occurs among diabetics and after abortions performed under unsanitary conditions. Moist gangrene is fatal unless treated with antibiotics. In severe cases amputation is necessary.