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T cells are important effector cells in natural antiviral and anticancer immunity. It is important to reveal the cellular and molecular requirements for T cell differentiation and effector functions. We explored the idea that the final outcome of antigen receptor-driven immune processes is at least partially determined by physiologically abundant small signaling molecules in extracellular envir...

principles of the student of general biology, who has been universally neglected in favor of the more specialized student of infectious diseases. It is designed primarily for the college senior or graduate student in biology; the references are intended to be illustrative of points requiring special emphasis rather than exhaustive in scope. The preface states: "Many controversial problems have ...

In addition to the bound purine moieties of DNA and RNA, plants and animals contain a variety of other purine derivatives ranging in decreasing structural complexity from free nucleotides to simple substituted bases. Many of these compounds play important roles in metabolism and in its control and integration. Whereas most of the purine derivatives found in animal tissues also occur in plants, ...

Two alternative approaches to the synthesis of novel 6-(fluoromethyl)purine bases and nucleosides are described either by direct deoxyfluorination or by multistep functional group transformations starting from 6-(hydroxymethyl)purines. 6-(fluoromethyl)purine ribonucleoside displayed significant cytostatic effects.

Milk xanthine oxidase exhibits a broad substrate specificity that includes purines, aldehydes, and pteridines (1). The mechanism of substrate oxidation, particularly that of purines, has been the subject of several studies (2-4). The present report concerns the observation of a new class of substrates, quaternary heterocyclic compounds, which are oxidized at pH values above 9.6. A partial list ...

Clostridium cylindrosporum spores germinated rapidly under reducing conditions when bicarbonate, uric acid, and calcium were present. Germination rates on 10 mM urate increased with increasing Ca (maximum rate at 5 mM Ca or greater). Germination rates on urate (limiting Ca) increased with increasing urate concentrations to 10 mM urate. At 10 mM Ca, germination rates reached a maximum at 1 mM ur...

The effects of catecholamines (dopamine, adrenaline, noradrenaline and its derivatives), 5-hydroxytryptamine and purines (adenosine, ATP and their derivatives) on the acetylcholine-induced luminescence of isolated arms and dissociated photocytes of the luminescent ophiuroid Amphipholis squamata were tested. The results showed that catecholamines and 5-hydroxytryptamine (10(-)(5) to 10(-)(3 )mol...

Purines are natural compounds that are found in all of the body's cells. They are the most widely distributed kind of N-heterocyclic substances in nature. Purines provide part of the chemical structure of some important co-enzymes and the genes of plants and animals. These compounds also participate in membrane signal transduction, translation and protein synthesis and in the form of purine nuc...