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 […]

Artemidorus: Artemidorus of Daldis. Greek physician who wrote Oneirocritica, a work dedicated to the interpretation of dreams, in the middle of the second century C.E. Artemidorus gathered evidence during interviews with thousands of people about their dreams. While his work has often been dismissed as mere divination, the careful study of dreams by modern psychiatrists […]

Inflammation of the tiny blood vessels of the retina. Retinal vasculitis ranges in severity from mild to severe. Damage to the blood vessels of the retina can cause minimal, partial, or even complete blindness. Retinal vasculitis by itself is painless, but many of the diseases that cause it can also cause painful inflammation elsewhere, such […]

Disease, cat scratch: A bacterial infection due to a cat scratch seen most often today in people with HIV. The disease characteristically presents with swollen lymph nodes (lymphadenitis), sore throat, fatigue, and fever, chills, sweats, vomiting, loss of appetite, and weight loss. There is usually a little bump (a papule) which may be pus-filled (a […]

High blood pressure, defined as a repeatedly elevated blood pressure exceeding 140 over 90 mmHg — a systolic pressure above 140 or a diastolic pressure above 90. Chronic hypertension is a “silent” condition. Stealthy as a cat, it can cause blood vessel changes in the back of the eye (retina), abnormal thickening of the heart […]

Embolus: A blockage or plug that obstructs a blood ‘vessel. Examples of emboli are detached blood clots, clumps of bacteria, and clumps of other foreign material, such as air.