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Biomedical subjects

R H Williams

Publications and source records attributed to R H Williams.

At least 109 records · Page 6Linked to original sources
PubMed1976

Apparent deficiency of vitamin B6 in typical individuals who commonly serve as normal controls.

Individuals who typically serve as normal controls were found by the differential assay of the glutamic oxaloacetic transaminase in their erythrocytes to have a deficiency (P less than 0.001) of enzyme activity as well as a deficiency (P less than 0.001) of pyridoxal phosphate. Contrary to the understanding that the diet provides an adequate intake of vitamin B6, the dietary intake of vitamin B6 of these controls was inadequate.

Adult↗
PubMed1975

Inhibition of gastrin release by somatosatin in vitro.

An in vitro system which uses perifused pieces from the antrum of rat stomach has been used to study the effect of dihydrosomatostatin on gastrin release. The gastrin concentration in fractions of the perfusate was measured by radioimmunoassay. Dihydrosomatostatin (2 x 10-7M) had no effect on basal gastrin levels but virtually abolished the biphasic response seen with argine stimulation. The study demonstrates close functional similarities between G cells and pancreatic islet cells.

Animals↗
PubMed1975

The effect on gastrin secretion of agents which increase the intracellular concentration of 3',5'-adenosine monophosphate.

An in vitro technique that allows study of gastrin secretion from isolated pieces of rat gastric antrum was used to study the effect on gastrin release of agents known to increase intracellular cAMP levels. Isuprel (10(-5)M), PGE1 (10(-5)M), theophylline (10(-4)M), and dibutyryl cAMP (5 X 10(-4)M) did not affect gastrin release when used alone, but each enhanced arginine-stimulated gastrin release. A biphasic pattern of gastrin release in response to arginine was seen in all experiments. The studies emphasize the close functional similarity between the antral G cells and the B cells of the pancreatic islet.

Animals↗
PubMed1975

Comparison of the lipolytic effects of insulin and proinsulin on isolated fat cells.

Proinsulin, like insulin, has a biphasic effect on the lipolysis of isolated fat cells. Low concentrations of the peptides inhibit the response to submaximal doses of epinephrine, while higher concentrations of the peptides enhance the effect of supramaximal doses of epinephrine. Half-maximal doses are: (a) inhibition of lipolysis: insulin, 2.3 times 10- minus 11M; proinsulin, 6.9 times 10- minus 10M; (b) enhancement of lipolysis: insulin, 3.1 times 10- minus 9M; proinsulin, 8.1 times 10- minus 8M. The ratios of the potencies of the peptides are the same for both effects. These results suggest that both the inhibitory and the lipolytic effects of insulin are not caused by contaminants, and are mediated by similar receptors.

Adipose Tissue↗
PubMed1975

New azasteroidal antifungal antibiotics from Geotrichum flavo-brunneum. II. Isolation and characterization.

A novel group of antibiotics, comprising microbiologically-active structurally-related factors A25822A, B, D, H, L, M and N, produced by culturing Geotrichum flavo-brunneum NRRL 3862 under submerged aerobic fermentation conditions was isolated by extraction. The individual factors were separated and purified by chromatography and crystallization. The major factor, A25822B, a 15-aza-24-methylene-D-homocholestadiene is a white crystalline compound, C25H45NO. The antibiotics are highly active against fungi and marginally active against bacteria.

Antifungal Agents↗
PubMed1975

Human deficiencies of vitamin B6. I. Studies on parameters of the assay of the glutamic oxaloacetic transaminase by the CAS principle.

Human deficiencies of vitamin B6 may be detected and accurately measured by a dual enzymic assay which is based on the CAS principle, i.e., the unsaturation and saturation of the coenzyme (pyridoxal 5'-phosphate) of a Coenzyme - Apoenzyme System. Glutamic oxaloacetic transaminase (GOT) is excellent for this assay. Two control groups (24 athletes and 25 students) showed deficiencies of GOT activity of 11+/-6% and 12+/-7%, respectively, which are negligible and which may be compared with analogous data from disease states. Contrary to a previous report, GOT activities must be determined within one day of preparation of the enzyme for meaningful assays. Frozen storage of erythrocyte hemolysates up to 21 days showed increasing apparent dissociation of pyridoxal 5'-phosphate from the coenzyme - apoenzyme system corresponding to increasing false deficiency levels. Dilution of the hemolysates and frozen storage augmented the apparent dissociation and false levels. This dual GOT assay is effective to detect and measure human deficiencies of vitamin B6.

Apoenzymes↗