A finger on the missing link

Article Abstract:

In the ongoing search for the origins of the HIV 1 virus, the causative agent for AIDS (acquired immunodeficiency syndrome), another virus from a chimpanzee has been genetically sequenced and found to be more closely related to HIV 1 than any previous primate virus to date. The two origin theories given here are that the HIV 1 virus was always around in the human population, in small amounts, and that some feature of modern society (air travel, drug use, sexual practices) facilitated its spread; or that humans have been infected via transmission from another species. Similar viruses have been isolated from sheep, goats, horses, cattle, cats, monkeys and humans; but the most similar to HIV 1 are the simian immunodeficiency viruses (SIVs) found in primates. In reality, the SIVs are more closely related to HIV 2, which is endemic in West Africa, and are only distant relatives of HIV 1, the presumed source of the current worldwide human infection. Viruses are commonly found throughout the animal kingdom which relate to each other and may reflect only an evolutionary, not direct, relationship. The source of these SIV virus infections in monkeys must still be determined, as they could have been infected by other monkeys or by a human source themselves. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diseases, HIV (Viruses), HIV, Origin, Chimpanzees

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Two functionally distinct alpha-2-adrenergic receptors regulate sympathetic neurotransmission

Article Abstract:

The alpha-2A and alpha-2C-adrenergic-receptor subtypes are needed for normal presynaptic control of transmitter release from sympathetic nerves in the heart and from central noradrenergic neurons in mice. Transmitter release at high stimulation frequencies is inhibited by alpha-2A-adrenergic receptors, while the alpha-2C-subtype controls neurotransmission at lower levels of nerve activity. It seems that the heart is exposed to substantially higher levels of catecholamines in alpha-2-AC-KO mice than in either alpha-2A-KO or alpha-2C-KO mice.

Mice, Mice (Rodents), Epinephrine, Neural transmission, Synaptic transmission, Adrenergic receptors

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Tat-specific cytotoxic T lymphocytes select for SIV escape variants during resolution of primary viraemia

Article Abstract:

Research is presented concerning the selection of new viral escape variants by Tat-specific CD8-positive T-lymphocyte responses during the acute phase of HIV infection. The possibilities of HIV vaccine development are discussed.

HIV infection, HIV infections, Vaccines, Letter to the Editor, Lymphocytes

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