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Biomedical subjects

J Newburger

Publications and source records attributed to J Newburger.

8 recordsLinked to original sources
PubMed1979

High steady-state levels of uric acid produced in rats by dietary training and potassium oxonate.

To reduce the inherent variability in serum uric acid levels of animals allowed ad libitum exposure to food containing potassium oxonate and uric acid, male Sprague-Dawley rats were trained to eat their daily food allotment in a 1.25-hr period each morning. After training the rats were fed a food mixture containing 5% potassium oxonate and 2% uric acid (w/w each). Serum blood levels of uric acid reached a steady state within 2 hr; these levels were maintained for an additional 4 hr. It is believed that the stomach emptying rate is a zero-order process under these experimental conditions.

Animals↗
PubMed1979

A method to predict infinity values for biexponential processes.

An equation is presented which allows infinity values for biexponential processes to be predicted in the early nonlinear phase when samples are taken at equal time intervals. This equation is independent of the value or ratio of the rate constants involved in the process. However, this method is very sensitive to noise normally associated with urine data.

Digoxin↗
PubMed1977

The effect of ion pair formation on the antimuscarinic activity of methantheline.

The quaternary ammonium compound, methantheline, was found to antagonize acetylcholine induced contractions in isolated guinea pig ileum by a mechanism which did not conform to the criteria for either competitive or non-competitive inhibition. Enhancement of the lipid solubility of methantheline by formation of an ion pair with trichloracetate failed to influence its cholinergic inhibitory activity. The results suggest that in the guinea pig ileum a) an intracellular site of action does not exist for methantheline and b) the membrane receptors for methantheline most likely are located in an aqueous environment.

Acetylcholine↗
PubMed1977

In vitro photodecomposition of uric acid in presence of riboflavin II.

In vitro studies on the photodecomposition of uric acid in the presence of the monosodium salt of riboflavin 5'-phosphate in buffers at various pH values, in methanol, and in human plasma are reported. The decomposition rate increased with increasing pH and was independent of solvent or buffer species. The mechanism appears to be an energy transfer process involving triplet riboflavin and single oxygen. Riboflavin-enhanced photodecomposition of uric acid occurred in vitro in hyperuricemic human plasma.

Chromatography, High Pressure Liquid↗