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 […]

A sting from a stinging insect, such as a bee, hornet, yellow jacket, or wasp, that can trigger allergic reactions. These reactions vary greatly in severity. Avoidance and prompt treatment are essential. In selected cases, allergy injection therapy is highly effective.

A bony spur projecting from the back or underside of the heel that often makes walking painful. Spurs at the back of the heel are associated with inflammation of the Achilles tendon (Achilles tendinitis) and cause tenderness and pain at the back of the heel that is made worse by pushing off the ball of […]

The abbreviation PEP stands for a number of things in medicine including post-exposure prophylaxis. Prophylaxis means a defense or protection. Post-exposure prophylaxis, for example, might concern the treatment of a health care worker exposed by a needle stick to HIV with a drug such as AZT to protect them from being infected with HIV.

The surgical repair of a hernia. Herniorrhaphy may be done under local or general anesthesia using a conventional incision or a laparoscope. The term “herniorrhaphy” comes from hernio-, referring to a hernia + the Greek rhaphe, a seam = putting a seam (or suture) in a hernia.

Wasting away, as occurs with children who have kwashiorkor. Also called cachexia, is usually a result of protein and calorie deficiency.