A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.

Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell […]

‘When you hear hoof beats, think of horses, not zebras.’ For example, when someone develops a mild transient cough, a virus infection is the most logical and likely cause, and tuberculosis is a zebra.

A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its […]

A technique in which a woman’s egg is fertilized outside the body, then implanted in one of her fallopian tubes. This technique is one of the methods used to overcome infertility, the inability of couples to produce offspring on their own. First, the egg and the male sperm needed to fertilize it are harvested. Then […]

Abbreviation for millimeters. For example, mm Hg means millimeters of mercury, the height of a column of mercury, as in a blood pressure reading. (In upper-case letters, MM stands for meningomyelocele, malignant melanoma, and multiple myeloma.)

An organic compound composed exclusively of hydrogen and carbon. All hydrocarbons have a carbon backbone with atoms of hydrogen attached to that backbone.

ALA: 1. Alpha-linolenic acid 2.Aminolevulinic acid, a naturally occurring chemical in the body that is converted to protoporphyrin IX, a light-sensitive compound. Aminolevulinic acid has been used in the photodynamic therapy of skin precancer and cancer. In this therapy topical treatment with forms of ALA sensitizes the tissues to light. Then a special blue or […]

Cardioversion: The conversion of a cardiac rhythm or electrical pattern to another, generally from an abnormal one to a normal one. Cardioversion can be accomplished by using medications or by electrical shock with a special defibrillator.

A version of a chemical element that has an unstable nucleus and emits radiation during its decay to a stable form. Radioisotopes have important uses in medical diagnosis, treatment, and research.