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Biomedical subjects

T E Webb

Publications and source records attributed to T E Webb.

At least 127 records · Page 7Linked to original sources
PubMed1975

Ribonucleic acid synthesis in isolated rat liver nuclei under conditions of ribonucleic acid processing and transport.

A cell-free system is described which permits a significant and prolonged synthesis of RNA in isolated rat liver nuclei, under conditions previously demonstrated to support normal nuclear processing and transport of both rRNA and mRNA. The system contains cytosol but not (NH4)2SO4 or other non-physiological components. Evidence is presented for cytosol factors which stimulate ribosomal, and to a lesser degree, non-ribosomal RNA synthesis.

Amanitins↗
PubMed1975

The dexamethasone receptor in the Novikoff Hepatoma. Characterization and changes in concentration and nuclear uptake during glucocorticoid therapy.

Novikoff hepatoma ascites cells, grown intraperitoneally in rats, are shown to possess a high-affinity, low-capacity dexamethasone-binding protein. The receptor protein has an intracellular localization and concentration, association constant (Ka), glucocorticoid specificity and nuclear uptake in the presence of dexamethasone comparable with those of the G-protein of rat liver. During therapy of the tumour-bearing animal with cortisol, marked cyclic variations were observed in the concentration and nuclear uptake of the putative G-protein in the tumor cells; more transient variations were also observed in the Ka value of the receptor protein.

Animals↗
PubMed1975

Modification of nuclear restriction in vitro by plasma from tumor-bearing animals.

Putative regulatory macromolecules, which may be useful in diagnosis or tumor detection, were identified in the peripheral blood plasma of tumor-bearing animals. We monitored the components by measuring their ability to stimulate messenger RNA (mRNA) release from isolated nuclei in a cell-free system of rat liver nuclei in fortified homologous cytosol. This in vitro test system exhibited near-normal in vivo nuclear RNA restriction. When added to the assay at a protein concentration of 3.0 mg/ml, dialyzed plasma from rats or mice with chemically induced transplantable or primary tumors stimulated mRNA release from 87% to more than 300% over control plasma from normal rats. Plasma from partially hepatectomized rats stimulated only 26% over control plasma. The test system derived from rat liver seemed to permit the monitoring of plasma from other species. Available evidence, particularly relating to tumor-host-interaction, suggests, but does not prove, that regulatory components are released from the tumor cells to the circulation.

Animals↗
PubMed1974

Modified messenger ribonucleic acid release from isolated hepatic nuclei after inhibition of polyadenylate formation.

Treatment of rats with Cordycepin (3'-deoxyadenosine), an inhibitor of nuclear poly(A) synthesis, selectively decreased the energy and cytosol-dependent release of a portion of the mRNA species from the isolated hepatic nuclei in a cell-free system by approximately 40%. An analysis of the differential binding of the transported mRNA containing poly(A) tracts to nitrocellulose filters, and to cellulose or poly(U)-Sepharose columns suggested that the poly(A) tracts in the mRNA transported from the isolated hepatic nuclei of Cordycepin-treated rats, are decreased in size. This size decrease was confirmed through an analysis of the average size of the poly(A) tracts, released from the messengers by ribonuclease activity, on sucrose density gradients.

Adenine Nucleotides↗