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Any of the organic compounds possessing one or more basic amino groups and one or more acidic carboxyl groups. Of the more than 80 amino acids that have been found in living organisms, approximately 20 serve as the building blocks for proteins.…

An acute, infectious worldwide zoonotic disease (transmissible to humans) caused by the spore-forming bacterium Bacillus anthracis to which most animals, especially grazing herbivores, are susceptible. Anthrax is a serious, though rare, infectious…

The capability that a bacterium acquires to counteract an inhibitory chemical molecule or compound that was formerly effective in killing it or preventing its growth. Antibiotic resistance in bacteria (Fig. 1) is a hot topic in the media and in…

Programmed cell death triggered by extracellular signals or genetically determined events and carried out by physiological processes within the cell. Apoptosis is one of the major forms of cell death in multicellular organisms (necrosis is the other…

The deposition of lipid with proliferation of fibrous connective tissue cells in the inner walls of the arteries. Atherosclerosis (Fig. 1) is the most common form of arteriosclerosis, which comprises a group of degenerative diseases of arteries…

A method for quantitatively determining the concentration, biological activity, or potency of a substance by its effect on the growth of a suitable animal, plant, or microorganism under controlled conditions. A bioassay (biological assay) is a…

Any of the genetically determined markers on the surface of cellular blood elements (red and white blood cells, and platelets). Blood groups (types) have medical, legal, and anthropologic importance. In medicine, the matching of ABO and Rh groups of…

The cancer death rate in the United States has fallen by 27% since 1991. According to the American Cancer Society, which compiled the data over a 25-year period from 1991 to 2016, a total of 2.6 million fewer individuals have died from cancer in the…

Cells within a tumor that possess the capacity to self-renew and cause the heterogeneous lineages of cancerous cells that comprise the tumor. Cancer stem cells (CSCs) typically represent a small percentage of all cells in a tumor (rarely more than…

The science of the electrical activity of the heart. Cardiac electrophysiology is the branch of cardiology concerned with the mechanism, spread, and interpretation of the electric currents that arise within heart muscle tissue and initiate each…