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Biomedical subjects

F C Kauffman

Publications and source records attributed to F C Kauffman.

At least 127 records · Page 7Linked to original sources
PubMed1979

p-Nitrophenol conjugation in perfused livers from normal and phenobarbital-treated rats: influence of nutritional state.

Conjugation of p-nitrophenol in perfused livers from control and phenobarbital-treated rats was measured spectrally by determining influent minus effluent concentration differences of the free drug. Rates of conjugation (1.0 to 2.0 mu moles/g/h) were essentially the same in livers from fasted control or fasted phenobarbital-treated rats. In control fed livers, rates of conjugation did not differ from the fasted state. However, rates of conjugation in livers from carbohydrate-rich, phenobarbital-treated rats were 6- to 10-fold greater than rates in livers from fasted phenobarbital-treated animals. Differences in rates of conjugation in phenobarbital-treated rats in different nutritional states were more closely related to carbohydrate reserves as indicated by glycogen levels than to activities of p-nitrophenyl UDP-glucuronyl transferase.

Adenine Nucleotides↗
PubMed1979

Stimulation of p-nitroanisole O-demethylation by ethanol in perfused livers from fasted rats.

Low concentrations of ethanol (0.2 mM) stimulated p-nitroanisole O-demethylation in perfused livers from fasted, but not fed, phenobarbital-treated rats. The increase in mixed-function oxidation correlated well with the production of NADH from ethanol metabolism (Ka for both processes = 0.2-0.3 mM). This stimulation by ethanol was blocked by 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, and pyruvate, a substrate for lactate dehydrogenase. Under these conditions, the characteristic reduction of NAD+ by ethanol was also abolished. p-Nitroanisole O-demethylation by isolated hepatic microsomes was unaffected by low concentrations of ethanol (up to 2 mM); however, when NADH was added to the microsomes, or was generated from ethanol, alcohol dehydrogenase and NAD+, a synergistic increase in p-nitroanisole metabolism occurred. Sorbitol and xylitol, two carbohydrates which reduced pyridine nucleotides in perfused livers, also stimulated p-nitroanisole O-demethylation in livers from fasted rats. The data indicate that NADH produced from the metabolism of ethanol, sorbitol and xylitol stimulates mixed-function oxidation in livers from fasted animals.

Alcohol Oxidoreductases↗
PubMed1978

Neuronal ischemic injury: light microscopy, ultrastructure and biochemistry.

A uniform, predictable pattern of cellular abnormalities is seen after complete, irreversible ischemic injury to the central nervous system. This is in contrast to the heterogeneous, multifocal picture which characterizes incomplete ischemia. The range of abnormalities in neuronal soma after an arterial occlusion changes considerably as a function of time and site. There is no single pattern of neuronal alteration that can be ascribed exclusively to ischemia. Red neurons are a relatively late (about 18 h) indicator of ischemia and are seen only in areas where blood supply is marginal. In addition to depletion of high-energy-phosphate reserves, brain ischemia results in characteristic alterations of amino acid concentrations in the ischemic tissue. Glutamate, glutamine, and aspartate either decrease or remain constant while alanine increases. Proportional decreases in the former three amino acids may be explained by simple dilution due to edema. Increases in alanine relative to glutamate and aspartate may be utilized as a biochemical index of perfusion to various brain regions.

Alanine↗
PubMed1978

The pentose phosphate pathway in regenerating skeletal muscle.

1. The activities of the oxidative enzymes (glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) and of the non-oxidative enzymes (transaldolase, tranketolase, ribose 5 phosphate isomerase and ribulose 5-phosphate 3-epimerase) of the pentose phosphate pathway were measured at various times during the first 24h of skeletal-muscle regeneration after administration of Marcaine, a mytoxic local anesthetic. 2. The activities of the oxidative enzymes increased after Marcaine injection and rose to 9 times control activities by 24h. 3. The activities of all non-oxidative enzymes were increased after Marcaine administration, but to a much smaller extent than the oxidative enzymes (1.1-1.7-fold). 4. Histochemical analysis localized glucose 6-phosphate dehydrogenase activity within muscle fibres of control and Marcaine-treated muscles. 5. Cycloheximide or actinomycin D prevented the increase in oxidative enzyme activities, suggesting a requirement for synthesis of protein and RNA.

Animals↗
PubMed1978

The effect of aldehyde fixation on selected substrates for energy metabolism and amino acids in mouse brain.

The effect of aldehyde fixation on concentrations of low molecular weight constituents was determined by comparing amounts of selected intermediates in brains of mice exposed to aldehyde fixative solutions with those perfused with phosphate buffer solution alone. Aldehyde perfusion resulted in excellent preservation of cerebral cortex ultrastructure in the presence of dramatic declines in adenosine triphosphate, phosphocreatine, glucose and glucose-6-phosphate that occureed before exposure of the tissue to aldehyde fixatives. Decreases in hexose were accompanied by approximately a 4-fold increase in lactate and a 2-fold increase in pyruvate. Glycogen levels decreased by about 60% during the initial operative procedure but remained constant after aldehyde fixation. Glycogen content declined approximately 90% in tissues that were not treated with aldehyde. Concentrations of aspartate and glutamate changed only slightly during the initial period (1-5 min) and remained constant for at least 90 min in cerebral cortices fixed with aldehydes. Alanine levels increased in both fixed and unfixed tissue; however, this increase was much smaller in tissues exposed promptly to aldehydes. Total ninhydrin-positive material in perchloric acid extracts of brain decreased in mice exposed to aldehyde solutions but increased in tissues that were not. These results indicated that several amino acids may be measured reliably in tissues preserved for light and electron microscopy. In addition, determination of glutamate: alanine ratios in tissues perfused with aldehydes may provide an indication of the timing of fixation.

Aldehydes↗
PubMed1977

Alterations in nicotinamide and adenine nucleotide systems during mixed-function oxidation of p-nitroanisole in perfused livers from normal and phenobarbital-treated rats.

The contents of adenine nucleotides as well as steady-state concentrations of a number of glycolytic, pentose phosphate-pathway and tricarboxylic acid-cycle intermediates were measured in extracts of livers from normal and phenobarbital-treated rats that were perfused with p-nitroanisole. Metabolites were measured in livers that were freeze-clamped during periods of maximal rates of drug metabolism. Treatment of rats with phenobarbital increased rates of p-nitroanisole O-demethylation approx. fivefold. The concentrations of lactate, xylulose 5-phosphate and ribulose 5-phosphate were increased by phenobarbital treatment, whereas that of fructose 1,6-bisphosphate declined. Perfusion of livers with p-nitroanisole produced significant increases in 6-phosphogluconate and ribulose 5-phosphate in livers from phenobarbital-treated rats, but not in livers from control rats. Treatment of rats with phenobarbital caused [NADP(+)]/[NADPH] to change in the direction of more oxidation, as calculated from measured concentrations of 6-phosphogluconate and ribulose 5-phosphate; however, the [NADP(+)]/[NADPH] ratio calculated from ;malic' enzyme was not changed. Additions of p-nitroanisole produced a reduction of NADP(+) as calculated from 6-phosphogluconate dehydrogenase activity, but did not alter the [NADP(+)]/[NADPH] ratio calculated from substrates assumed to be in equilibrium with ;malic' enzyme. Activities of both glucose 6-phosphate dehydrogenase and ;malic' enzyme were increased by phenobarbital treatment. NAD(+) became more reduced as a result of phenobarbital treatment; however, perfusion of livers with p-nitroanisole did not cause a change in the oxidation-reduction state of this nucleotide. Concentrations of adenine nucleotides in livers were not altered significantly by treatment of rats with phenobarbital; however, a significant decline in the [ATP]/[ADP] ratio occurred during mixed-function oxidation of p-nitroanisole in livers from phenobarbital-treated rats, but not in livers from normal rats. Perfusion of livers with two other substrates for mixed-function oxidation, hexobarbital and aminopyrine, produced an increase in the [NADP(+)]/[NADPH] ratio calculated from ;malic' enzyme. In contrast with livers perfused with p-nitroanisole, there was no significant change in adenine nucleotides in livers exposed to hexobarbital or aminopyrine. Addition of 2,4-dinitrophenol (25mum) to the perfusate containing aminopyrine decreased the [ATP]/[ADP] ratio and tended to prevent the oxidation of NADPH observed with aminopyrine alone. Thus in the presence of an uncoupler of oxidative phosphorylation, NADPH generation may exceed its utilization via mixed-function oxidation.

Adenine Nucleotides↗
PubMed1977

Metabolic factors in surgery of peripheral nerves.

Respect for the metabolic changes within the neuron is critical in planning peripheral nerve surgery. Only by understanding the different metabolic responses of the nerve tissue and the supportive tissue can anastomosis be planned where the budding neuron stands its best chance of successfully regenerating across a repair site. Often, a short delay in nerve repair is indicated. With all factors ideal, good motor function can be counted on across one joint from the next group of muscles. Rarely is there good function across two joints. Protective sensory function can be achieved distally even under the most adverse metabolic conditions because of the independent metabolic state of these end organs.

Age Factors↗
PubMed1977

The continuous kinetic determination of p-nitroanisole O-demethylation in hemoglobin-free perfused rat liver.

P-Nitroanisole O-demethylation by perfused rat liver based on the spectral properties of the product, p-nitrophenolate, was determined continuously. Rates of p-nitrophenol production in this system were sensitive to inhibition by CO. p-Nitrophenolate production by livers of normal animals was linear for up to 30 minutes; however, rates were only linear for 1 to 2 minutes followed by a steady decline in induced (6-fold) livers from phenobarbital-treated rats. Only a small portion (24%) of this steady decline could be accounted for by the formation of conjugation products. Additionally, infusion of p-nitrophenol (14 micronM) was not associated with a decline in rate. The decline in rate in induced livers was reversed by glucose, suggesting that an intimate relationship may exist between drug and carbohydrate metabolism in the intact liver. Alteration in rates of p-nitroanisole metabolism with various inducing agents of the mixed-function oxidation system (phenobarbital; ethanol) produced parallel changes in rates of hepatic lactate production, most likely reflecting the aciton of p-nitrophenol to uncouple oxidative phosphorylation. The data support the hypothesis that the decline in rate in p-nitroanisole O-demethylation in livers from phenobarbital-treated rats is due to reduced availability of NADPH for mixed-function oxidation.

Animals↗