• Z chromosome

    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.

  • ZAP-70

    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 […]

  • Zebra

    ‘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.

  • Zygotic lethal gene

    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 […]

  • Zygote intrafallopian transfer (ZIFT)

    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 […]

  • Medicare Part B

    The Medicare program that covers physician and outpatient services. Medicare is the United States government’s health insurance program for the aged and some disabled persons. Medicare is currently available to people 65 and older and to people with certain disabilities. Medicare Part A covers inpatient hospital stays.

  • Transplantation, peripheral blood stem cell

    A technique in which stem cells are obtained from a patient’s blood and used in bone marrow transplantation. Stem cells are small, round cells with a squat nucleus and scant surrounding cytoplasm. Although unremarkable in appearance, stem cells can perform what have been called “acts of biological resurrection.” Whereas other types of cells in the […]

  • Deficiency, UDP-glucuronosyltransferase

    Deficiency, UDP-glucuronosyltransferase: Underactivity of a liver enzyme that is essential to the disposal of bilirubin (the chemical that results from the normal breakdown of hemoglobin from red blood cells). The deficiency of this enzyme (UDP-glucuronosyltransferase) results in a condition called Gilbert’s disease in which there are mild elevations of bilirubin pigment in the blood. The […]

  • ADA (American Dental Association)

    ADA (American Dental Association): The mission statement of the ADA reads as follows: “The ADA is the professional association of dentists dedicated to serving both the public and the profession of dentistry. The ADA promotes the public’s health through commitment of member dentists to provide quality oral health care, accessible to everyone. The ADA promotes […]

  • Allergy, cow milk

    Allergy, cow milk: Casein and whey are the two major proteins of human milk and most milk-based formulas. Some (less than 8% of) infants have a true allergy to the cow proteins that are in milk-based formulas. Infants with true cow milk allergy can develop abdominal pain, diarrhea, rectal bleeding, skin rash, and wheezing when […]