Definition of Agency for Toxic Substances and Disease Registry

Agency for Toxic Substances and
Disease Registry: An agency of the U.S. Department of Health and Human Services under the Public Health Service that works with states and
other federal agencies to prevent exposure to hazardous substances from waste
sites. The agency conducts public health assessments, health studies,
surveillance activities, and health education training in communities around
waste sites on the U.S. Environmental Protection Agency's National Priorities
List. ATSDR also has developed toxicological profiles of hazardous chemicals found at these sites. Established: 1980. Headquarters: Atlanta, GA.

Definition of Age-related macular degeneration

Age-related macular degeneration: An eye disease with its onset usually after age 60 that progressively destroys the macula, the central portion of the retina, impairing central vision. Age-related macular degeneration (AMD) rarely causes blindness because only the center of vision is affected. However, injury to the macula in the center of the retina can impair the ability to see straight ahead clearly and sometimes make it difficult to read, drive, or perform other daily activities that require fine central vision.
The macula is in the center of the retina at the back of the eye. As we read, light is focused onto the macula where millions of cells change the light into nerve signals that travel to the brain and tell it what we are seeing. This is our central vision. With normal central vision, we are able to read, drive, and perform other activities that require fine, sharp, straight-ahead vision.



There are two types of AMD -- the dry type and the far more frequent wet type. Neither type causes pain. An early symptom of wet AMD is that straight lines appear wavy. This happens because the newly formed blood vessels leak fluid under the macula. The fluid raises the macula from its normal place at the back of the eye and distorts vision. Another sign that a person may have wet AMD is rapid loss of central vision. This is different from dry AMD in which loss of central vision occurs slowly. In both dry and wet AMD, the person may also notice a blind spot. If any of these changes in vision is noticed, an ophthalmologist should be consulted without delay.
Supplements of zinc and the antioxidants vitamin C, vitamin E and beta-carotene reportedly slow the progression of wet AMD. In people with intermediate-stage disease, zinc reduced the risk of the disease progressing to the advanced stage by 11%, and the antioxidants reduced the risk by 10%. When the two were combined, the risk was reduced by 19%. The daily doses of the antioxidants used in the study were 500 milligrams of vitamin C, 400 milligrams of vitamin E and 15 milligrams of beta-carotene (a molecule the body converts to vitamin A). The daily dose of zinc was 80 milligrams with 2 milligrams of copper. These amounts are well above the usual levels recommended by the Food and Drug Administration (FDA): 3 times as much vitamin A, 8 times as much vitamin C, 13 times as much vitamin E and 5 times as much zinc.
For a fuller consideration of this disorder, see the article on Age-related macular degeneration.

Definition of Age-related deafness

Age-related deafness: See: Presbycusis.

Definition of Age by decade

Age by decade: A term designating someone's age by decade. For example, a septuagenarian refers to someone in his or her seventies (age 70 to 79). The prefix in such terms is always from the Latin. For example, the Latin septuageni = seventy.

Denarian: Someone age 10 to 19.
Vicenarian: Someone in his or her twenties.
Tricenarian: Someone in his or her thirties.
Quadragenarian: Someone in his or her forties.
Quinquagenarian: Someone in his or her fifties.
Sexagenarian: Someone in his or her sixties.
Septuagenarian: Someone in his or her seventies.
Octogenarian: Someone in his or her eighties.
Nonagenarian: Someone in his or her nineties.
Centenarian: Someone 100 or more.
Supercentenarian: Someone 110 years old or more (no upper limit).
The terms denarian, vicenarian, tricenarian, and quadragenarian are not in common usage. The term supercentenarian was coined in 1991.

Definition of African-American

African-American: See: African American.

Definition of African tick typhus

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 fievre boutonneuse.

Definition of African sleeping sickness

African sleeping sickness: Also called African trypanosomiasis, a systemic disease caused by the parasite Trypanosoma brucei that is
transmitted by the bite of the tsetse fly, a gray-brown insect about the size of
a honeybee. African trypanosomiasis is confined to tropical Africa from north of
South Africa to south of Algeria, Libya, and Egypt. Tsetse flies inhabit rural
areas only, living in the woodland and thickets of the savannah and the dense
vegetation along streams. Although infection of international travelers was considered rare, the number of cases in travelers, primarily to East African game parks, has increased in recent years. Travelers visiting game parks and remote areas should take precautions. Travelers to urban areas are not at risk.

The signs and symptoms of the infection are initially nonspecific (high fever, rash, edema, or swollen glands) but
the disease progresses to encephalitis and meningitis. Symptoms generally appear
within 1 to 3 weeks of infection. Untreated cases are eventually fatal. People
who have had tsetse fly bites or become ill with high fever or other
manifestations of African trypanosomiasis are advised to seek early medical
attention. The infection can usually be cured by an appropriate course of
anti-trypanosomal therapy. Pentamidine isethionate and suramin are the drugs of
choice to treat the hemolymphatic stage of West and East African trypanosomiasis, respectively. Melarsoprol is the drug of choice for late disease with central nervous system involvement.
No vaccine is available to prevent this disease. Tsetse flies are attracted to moving vehicles and dark, contrasting colors. They are not affected by insect repellents and can bite through lightweight clothing. Areas of heavy infestation tend to be sporadically distributed and are usually well known to local residents. Avoidance of such areas is the best means of protection. Travelers at risk should be advised to wear clothing of wrist and ankle length that is made of
medium-weight fabric in neutral colors that blend with the background
environment.