- H -

HIV

HIV Virus.A (âch´ì-vê¹) noun or Human Immunodeficiency a retrovirus that causes AIDS. HIV was formerly known as HTLV-III.

 

Hormone

hormone, chemical messenger released in minute amounts by the endocrine, or ductless, glands and carried by the bloodstream to target tissues, where it produces either rapid or long-term effects. Most hormones fall into two major categories: PEPTIDES (chains of amino acids) and LIPIDS (including STEROIDS). Since the lack of any hormone may cause serious disorders, many hormones are now synthesized for use in treating such deficiencies.2

Huntington's disease

Huntington's disease, formerly Huntington's chorea, hereditary disease of the central nervous system, beginning usually in middle age and characterized by involuntary jerky movements, personality changes, and progressive mental deterioration. It is caused by a mutated gene on chromosome 4. The child of a person with Huntington's has a 50% chance of inheriting the gene, which inevitably leads to the disease

 

Hydrolysis

hydrolysis (hì-dròl¹î-sîs), chemical reaction of a compound with WATER, usually resulting in the formation of one or more new compounds. The most common hydrolysis occurs when a salt of a weak acid or weak base (or both) is dissolved in water. Water ionizes into negative hydroxyl ions (OH-) and positive hydrogen ions (H+), which become hydrated to form positive hydronium ions (H3O+). The salt also breaks up into positive and negative ions, and the formed ions recombine. 1

Hydroxylate

 

hy·drox·yl·ate (hì-dròk¹se-lât´) verb, transitive hy·drox·yl·at·ed, hy·drox·yl·at·ing, hy·drox·yl·ates

To introduce hydroxyl into (a compound). — hy·drox´y·la¹tion 2

 

- I -

Immune System

immune system (noun) The integrated body system of organs, tissues, cells, and cell products such as antibodies that differentiates self from nonself and neutralizes potentially pathogenic organisms or substances. 2

Immunodeficiency

immunodeficiency (îm´ye-no-dî-fîsh¹en-sê, î-my¡¹-) noun plural im·mu·no·de·fi·cien·cies An innate, acquired, or induced inability to develop a normal immune response. 2

— im´mu·no·de·fi¹cient adjective