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Biomedical subjects

L Clark

Publications and source records attributed to L Clark.

At least 181 records · Page 10Linked to original sources
PubMed1979

A new radioassay for serum vitamin B12 determination using chicken serum as a binder and an anion exchange resin column separation.

We present a new method for the determination of serum vitamin B12 concentration by competitive protein binding using 57Co labeled vitamin B12, chicken serum (CS) as the binding protein, and a sephadex column separation. We placed a mixture of extracted sample, labeled B12, and CS binder above an A-25 sephadex column, and after 1 hour incubation at room temperature drained the column and washed it twice with buffer. We counted the free fraction remaining in each column. Within run C.V.'s for low and high values in the normal range were 10.6% and 6.03%. The between run C.V.'s were 7.7% and 7.5% respectively. The values obtained for 95 clinical specimens correlated well with those for a reference method.

Animals↗
PubMed1978

Changes in the caecal flora associated with the onset of laminitis.

Caecal fluid samples collected 8 and 24 hours after carbohydrate overload were quantitatively compared to control samples in terms of aerobic and anaerobic bacteria. Concomitant increases in lactic acid-producing bacteria and decreases in Gram negative bacteria were substantiated during the onset of acute laminitis. Progressive decreases in caecal fluid pH were also quantitated. Although endotoxin assays of caecal fluid and blood were not done, the caecal flora changes suggest its presence during the onset of acute laminitis.

Animals↗
PubMed1977

Influence of fasting-refeeding and dietary linoleate on liver glucose-6-phosphate dehydrogenase and phospholipid fatty acid composition in rats adapted to a purified diet.

Responses to refeeding after fasting were studied in male rats fed a purified casein-sucrose diet containing 5% safflower oil. After a 48 hr fast, the rats were fed either the same diet or the same diet minus oil (fat-free diet). These experiments were designed to distinguish changes due to fasting and refeeding alone without a change of diet from those changes caused by refeeding a diet of different composition. In the first experiment, rats were refed for 3 or 7 days. In rats refed either diet, liver glucose-6-phosphate dehydrogenase (G6PD) activity was elevated above refasting levels, but after 7 days, activity in rats refed the 5% safflower oil diet was significantly lower than in those refed the fat-free diet. The amount of liver arachidonate in rats refed the safflower oil diet was the same during refeeding as before fasting. In the second experiment, rats were refed the fat-free diet for 1, 2, 3, or 7 days. Liver G6PD and fatty acid synthetase were measured, as well as fatty acids in liver total lipids and phospholipids. G6PD activity increased above prefasting levels after one day refeeding and continued to increase for 7 days. Fatty acid synthetase activity increased for the first 3 days of refeeding, with no additional increase after 7 days. In all rats refed the fat-free diet, the proportions of arachidonate and linoleate in liver phospholipids diminished with time, and eicosatrienoate appeared. These results show that (a) maintenance of liver phospholipid arachidonate did not prevent increased G6PD activity in early refeeding, but the elevated G6PD activity later declined when phospholipid arachidonate was maintained by feeding a source of linoleate; (b) the metabolic state of fasted-refed rats had not returned to prefasting conditions even after 7 days of refeeding a linoleate-rich diet to which the rats were adapted before fasting.

Animals↗
PubMed1976

Laboratory hazards.

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Accident Prevention↗