PubMed Health⌕ Search

Biomedical subjects

T M Devlin

Publications and source records attributed to T M Devlin.

At least 55 records · Page 3Linked to original sources
PubMed1979

Regulation of mammalian protein synthesis in vivo. Simulated transport of nuclear ribonucleoprotein complexes to the cytoplasm after cycloheximide treatment.

By studies in vivo with purified nuclei from rat liver, it was shown that a non-lethal dose of cycloheximide causes a decrease in the content of total nuclear ribonucleoprotein complexes by 2h after treatment. Analysis of the complex by sucrose-density-gradient centrifugation substantiated this observation for the faster-sedimenting complex, but showed an increase in the content of a smaller complex. Radioisotope incorporation studies showed that the overall decrease in nuclear ribonucleoprotein content was not due to a decreased synthesis, but rather to an increased transport to the cytoplasm. The results of a double-radioisotope technique support the conclusion that, during the inhibitory phase of protein synthesis brough on by cycloheximdie, gene transcription continues and the gene product is transported to the cytoplasm for subsequent translation.

Animals↗
PubMed1979

Cycloheximide as a probe of fibrinogen synthesis.

Fibrinogen synthesis in the intact rat was perturbed by treatment with cycloheximide. Specific radioactivities of fibrinogen in plasma and liver both decreased at 2 h after treatment and increased over 2-fold by 18 h. Labelled-antibody--polyribosome binding experiments showed that more polyribosomes were engaged in fibrinogen synthesis at 18 h after treatment. Radioactivity of plasma fibrinogen chains from untreated control rats showed a constant ratio of A alpha--B beta/gamma = 1.03. At 2 h after cycloheximide treatment the A alpha- and B beta-chains showed the greatest decrease in labelling (A alpha--B beta/gamma = 0.66) and at 18 h all chains were much more labelled (the A alpha--B beta/gamma ratio chainged to 1.39). The observed imbalance in fibrinogen-chain synthesis suggests that cycloheximide has a selective effect on gene expression.

Animals↗
PubMed1977

Regulation of mammalian protein synthesis in vivo. Stimulated liver ribonucleic acid synthesis in vivo after cycloheximide treatment.

1. As shown by a double-radioisotope technique in vivo, at a non-lethal dose of cycloheximide, a stimulation of nuclear RNA synthesis occurred by 12 h after the treatment; the stimulation lasted over 48 h. Analysis of radioactive nuclear RNA by gel electrophoresis demonstrated that most of the cycloheximide-stimulated synthesis could be accounted for by known rRNA precursors (45 S, 41 S, 32 S and 28 S). 2. During the inhibitory phase of protein synthesis, 2 h after cycloheximide treatment, synthesis of the poly(A)-containing mRNA isolated from the cytoplasmic ribonucleoprotein complexes with an oligo(dT)-cellulose column was stimulated, whereas the synthesis of rRNA was slightly inhibited. However, during the stimulatory phase of protein synthesis, 24 h after cycloheximide treatment, the syntheses of both poly(A)-containing mRNA and rRNA were enhanced. 3. Kinetic studies revealed that the newly synthesized RNA species were transported from the nuclei, integrated into the ribonucleoprotein complexes, and associated with both free and membrane-bound polyribosomes. 4. These data corroborate our proposal that the stimulated protein synthesis after cycloheximide administration involves gene transcription.

Animals↗
PubMed1977

Regulation of mammalian protein synthesis in vivo. Stimulated protein synthesis in liver in vivo after cycloheximide treatment.

Protein synthesis in rat liver in vivo was measured between 0 and 72 h after administration of a non-lethal dose of cycloheximide. There was a period of inhibition of [3H]leucine incorporation into both intra- and extra-cellular proteins at 2 h after administration of the drug, which was followed by a recovery phase in which amino acid incorporation varied significantly among the various proteins evaluated. At 12 h there was a marked stimulation of incorporation into nascent polypeptides released from polyribosomes and plasma fibrinogen, but incorporation into ribosomal proteins as well as albumin was still inhibited. Between 12 and 48 h, nascent-polypeptide synthesis remained elevated, but ribosomal-protein synthesis recovered slowly from the inhibition to normal rates only, and plasma-albumin synthesis increased slowly to above control values up to 48 h before returning to normal. A differential pattern of incorporation was also observed for incorporation into free and membrane-bound polyribosomes.

Animals↗
PubMed1976

Regulation of mammalian protein synthesis in vivo. Protein synthesis in rat liver and kidney after the administration of sublethal doses of cyclohyximide.

Protein synthesis in vivo was studied at various times after the administration of sublethal doses of cycloheximide to rats. Cycloheximide caused an inhibition, followed by a dose-and time-dependent stimulation, of incorportation of labelled precursor into proteins of the liver and kidney. The stimulation of protein synthesis at 24h was not due to a change of precursor pool or the specific radioactivity of the precursor used. During the stimulatory period, leucine incorporation into various cellular protein fractions varied; incorporation into total nuclear protein was the most affected.

Amino Acids↗
PubMedDate not supplied

Prostaglandin Bx in the prevention of stress ulcers in rats.

The effect of Prostaglandin Bx (PGBx) on the development of gastric stress ulceration and bleeding in rats was investigated. The rats were divided into five groups and each rat was injected intravenously with either Saline (control), 0.5 mg, 1 mg, 5 mg, or 25 mg/kg of PGBx, according to group. The rats were then placed in wire conduit cages and placed in a cold room at 4 degrees C for three hours and sacrificed immediately afterwards. Results showed a significant increase in gastric bleeding and ulceration in the groups that received 1 and 5 mg/kg (PGBx) when compared to the control group (p less than 0.01). There was, however, a significant increase in gastric acid output in the group that received 1 mg/kg PGBx when compared to the control group (p less than 0.01). Our results suggest that PGBx, by a mechanism other than the inhibition of gastric acid secretion, maintains the integrity of the gastric mucosa.

Animals↗