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G D Williams

Publications and source records attributed to G D Williams.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

31P NMR spectroscopy of perinatal hypoxic-ischemic brain damage: a model to evaluate neuroprotective drugs in immature rats.

Cerebral energy metabolism can be measured non-invasively in unanesthetized neonatal rats with 31P NMR spectroscopy. Using this technique, serial changes in high energy phosphates were determined from the right cerebral hemispheres of 7 day postnatal rat pups during a hypoxic-ischemic insult known to produce focal brain injury. During 3 h of hypoxia-ischemia the concentration of ATP dropped to 33 +/- 8% of prehypoxic (baseline) levels, phosphocreatine (PCr)/Pi decreased from 1.5 +/- 0.51 to 0.16 +/- 0.06, while pH decreased nominally by 0.2 units. After 2.5 h of recovery in air, ATP returned to 75 +/- 10% of baseline levels, PCr/Pi rose to 1.1 +/- 0.28, and pH returned to its normal value of 7.16 +/- 0.06. This model was used to test the efficacy of the adenosine deaminase inhibitor, 2-deoxycoformycin (DCF) as a potential neuroprotective drug. The data for the drug- and saline-treated populations were analyzed by integrating ATP and Pi/PCr levels over specific time intervals, expressing it relative to baseline levels, and modeling it with cubic splines. Pretreatment with 500 micrograms/kg DCF shows a small, but statistically significant, preservation of both ATP and phosphorylation potential during hypoxia and initial recovery. Brain water content (edema) at 42 h recovery was apparently associated with both mean ATP and mean Pi/PCr in the last 2 h of hypoxia-ischemia. When ATP fell below 70% of baseline, brain edema was evident at 42 h of recovery. This methodology is suitable for extension to human infants.

Adenosine Triphosphate↗
PubMedDate not supplied

Compound M & B 39890A [N-(3-imidazol-1-ylpropyl)- 2-(3-trifluoromethylbenezensulphonamido)-benzamide hydrochloride], a glucagon and insulin secretion inhibitor, improves insulin sensitivity in viable yellow obese-diabetic mice.

Compound M & B 39890A [N-(3-imidazol-1-ylpropyl)-2- (3-trifluoromethylbenzenesulphonamido)benzamide hydrochloride] had no effect on cellular cAMP and cGMP levels but significantly inhibited insulin and glucagon secretion from freshly isolated normal rat islets stimulated with 10 mM glucose and 20 mM arginine. Daily gavage of the compound for three days lowered the elevated blood glucose and plasma insulin levels in fed, male viable yellow obese-diabetic mice; the minimum effective dose was 25 mg/kg. However, M & B 39890A did not affect the blood glucose level of fasted diabetic mice. In addition, it had no effect on blood glucose levels of normal mice and streptozotocin-diabetic rats. M & B 39890A, fed in the diet at the concentration of 1 mg/g for 42 days, reversed the hyperglycemia of the fed diabetic mice without causing tachyphylaxis and improved the sensitivity to exogenous insulin as demonstrated by the lowering of blood glucose. When M & B 39890A was fed to young male mice destined to become diabetic, the development of hyperglycemia was prevented. Thus, M & B 39890A represents a new class of pharmacological agents that may prove to be effective for the chronic treatment of type II diabetics without the risk of hypoglycemia.

Animals↗