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Biomedical subjects

O Black

Publications and source records attributed to O Black.

29 records · Page 2Linked to original sources
PubMed1973

Hormonal control of pancreatic growth.

Investigations have outlined pancreatic secretory and synthetic responses to gastrointestinal hormones. However, there is little information concerning hormonal influences on pancreatic growth. These studies were designed to examine effects of chronic administration of bethanechol and cholecystokinin-pancreozymin (CCK-PZ) on the pancreas. Male albino rats were given saline, bethanechol, 6 mg/kg, or CCK-PZ, 20 U/kg, intraperitoneally twice daily and killed after 5 days. The following changes were studied; pancreatic weight; RNA, DNA, and protein content; and [(14)C]thymidine incorporation into DNA. Bethanechol administration was associated with a 20% increase in pancreatic weight and a 33% increase in mg protein/100 mug DNA. In bethanechol-treated groups, amounts of DNA/gram body weight and incorporation of [(14)C]thymidine into DNA were similar to controls. CCK-PZ administration was associated with a 71% increase in pancreatic weight and a 38% increase in mg protein/100 mug DNA. In CCK-PZ-treated groups, amounts of DNA/gram body weight were increased by 42% and [(14)C]thymidine incorporation into DNA was increased by 185%. These studies indicate that bethanechol administration was associated with increases in pancreatic cell mass (hypertrophy). CCK-PZ administration was associated with increases in cell mass and cell numbers (hypertrophy and hyperplasia). This information suggests the importance of CCK-PZ in maintaining pancreatic functional integrity. Although bethanechol and CCK-PZ elicit similar secretory responses, their mode of action on the cell, at least as far as growth influences are concerned, appears to be different.

Animals↗
PubMed1972

Ontogenetic changes of proteins of endoplasmic reticulum.

The proteins of the smooth and rough endoplasmic reticulum from fetal, immature, and adult male rats were compared after incorporation of two radioactively labeled precursors, (14)C-labeled amino acids and delta-aminolevulinic acid-(3)H by means of gel electrophoresis. The labeling patterns indicated that protein components present in two major electrophoretic bands underwent significant synthesis in fetal tissue while three actively incorporating protein bands were noted in adult tissue. Although the uptake of the amino acids-(14)C decreased for the smooth and rough elements of the endoplasmic reticulum as a whole during liver development, the qualitative patterns were not significantly different in adult and fetal livers. The over-all incorporation (disintegrations per minute per milligram protein) of the heme precursor into the smooth and rough elements also did not change with development. However, a change was noted in the distributional electrophoretic patterns with development. The estimation of molecular weight (by disc electrophoresis) and the incorporation of the heme precursor suggested the similarity of the two major protein bands to cytochrome P-450 and cytochrome b(5), components of the endoplasmic reticulum, thought to be involved in the mixed-function oxidase system. The evidence indicated that in fetal liver, at a time when the oxidase capability was low, the amino acid incorporation into these two protein groups was the same as in the adult. The incorporation of the heme moiety, however, was different, decreasing in the cytochrome b(5) region and increasing in the cytochrome P-450 region during development. These results correlate with the increase in oxidase activity associated with liver development.

Amino Acids↗