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Biomedical subjects

R L Veech

Publications and source records attributed to R L Veech.

At least 109 records · Page 6Linked to original sources
PubMed1978

Lactate-stimulated ethanol oxidation in isolated rat hepatocytes.

1. Hepatocytes isolated from starved rats and incubated without other substrates oxidized ethanol at a rate of 0.8-0.9mumol/min per g wet wt. of cells. Addition of 10mm-lactate increased this rate 2-fold. 2. Quinolinate (5mm) or tryptophan (1mm) decreased the rate of gluconeogenesis with 10mm-lactate and 8mm-ethanol from 0.39 to 0.04-0.08mumol/min per g wet wt. of cells, but rates of ethanol oxidation were not decreased. From these results it appears that acceleration of ethanol oxidation by lactate is not dependent upon the stimulation of gluconeogenesis and the consequent increased demand for ATP. 3. As another test of the relationship between ethanol oxidation and gluconeogenesis, the initial lactate concentration was varied from 0.5mm to 10mm and pyruvate was added to give an initial [lactate]/[pyruvate] ratio of 10. This substrate combination gave a large stimulation of ethanol oxidation (from 0.8 to 2.6mumol/min per g wet wt. of cells) at low lactate concentrations (0.5-2.0mm), but rates remained nearly constant (2.6-3.0mumol/min per g wet wt. of cells) at higher lactate concentrations (2.0-10mm). 4. In contrast, owing to the presence of ethanol, the rate of glucose synthesis was only slightly increased (from 0.08 to 0.12mumol/min per g wet wt. of cells) between 0.5mm- and 2.0mm-lactate and continued to increase (from 0.12 to 0.65mumol/min per g wet wt. of cells) with lactate concentrations between 2 and 10mm. 5. In the presence of ethanol, O(2) uptake increased with increasing substrate concentration over the entire range. 6. Changes in concentrations of glutamate and 2-oxoglutarate closely paralleled changes in the rate of ethanol oxidation. 7. In isolated hepatocytes, rates of ethanol oxidation are lower than those in vivo apparently because of depletion of malate-aspartate shuttle intermediates during cell preparation. Rates are returned to those observed in vivo by substrates that increase the intracellular concentration of shuttle metabolites.

Animals↗
PubMed1978

Effect of chronic ethanol administration on cholesterol and bile acid synthesis in vivo.

Chronic administration of ethanol failed to a stimulate the hepatic rate of cholesterol synthesis in meal-fed rats. In contrast, chronic ethanol feeding caused a 50% inhibition in the rate of incorporation of [4-14C] cholesterol to bile acids in the bile-duct cannulated rats. It is, therefore, suggested that the decreased rate of cholesterol degradation to bile acids may play an important role in ethanol-induced accumulation of cholesterol in liver.

Alcoholism↗
PubMed1978

A rapid, enzymatic assay for the measurement of inorganic pyrophosphate in animal tissues.

A simple, rapid enzymatic assay for the determination of inorganic pyrophosphate in tissue and plasma has been developed using the enzyme pyrophosphate--fructose-6-phosphate 1-phosphotransferase (EC 2.7.1.90) which was purified from extracts of Propionibacterium shermanii. The enzyme phosphorylates fructose-6-phosphate to produce fructose-1,6-bisphosphate using inorganic pyrophosphate as the phosphate donor. The utilization of inorganic pyrophosphate is measured by coupling the production of fructose-1,6-bisphosphate with the oxidation of NADH using fructose-bisphosphate aldolase (EC 4.1.2.13), triosephosphate isomerase (EC 5.3.1.1), and glycerol-3-phosphate dehydrogenase (NAD+)(EC 1.1.1.8). The assay is completed in less than 5 min and is not affected by any of the components of tissue or plasma extracts. The recovery of pyrophosphate added to frozen tissue powder was 97 +/- 1% (n = 4). In this assay the change in absorbance is linearly related to the concentration of inorganic pyrophosphate over the curvette concentration range of 0.1 microM to 0.1 mM.

Animals↗
PubMed1977

Regulation of lipogenesis in isolated hepatocytes by triglyceride-rich lipoproteins.

Very low density lipoproteins, chylomicrons, and remnants caused, within an hour, significant inhibition of fatty acid synthesis but not cholesterol synthesis in hepatocytes isolated from meal-fed rats. In contrast, low density lipoproteins, high density lipoproteins, and the serum fraction of density greater than 1.21 failed to significantly inhibit either fatty acid or cholesterol synthesis within 1 h. The Scatchard plots of specific binding showed that rat and human very low density lipoproteins interact with the high affinity sites on the hepatocytes with the apparent dissociation constants of 64 and 106 nM, respectively. These data also indicated that each hepatocyte was capable of binding 6 X 10(5) molecules of very low density lipoproteins.

Animals↗
PubMed1977

Short- and long-term effects of ethanol administration in vivo on rat liver HMG-CoA reductase and cholesterol 7alpha-hydroxylase activities.

Short- and long-term effects of ethanol on HMG-CoA reductase (EC 1.1.1.34) and cholesterol 7alpha-hydroxylase activities in rat liver have been investigated. Neither the reductase nor the hydroxylase activity as measured in vitro was significantly affected within 2 hr after a single intraperitoneal injection of ethanol (7 mmol per 100g body weight), whether tested at the diurnal low or the diurnal high point of activity. Although chronic ethanol feeding for 21 days did not affect the diurnal rhythm of either of these enzyme activities, it caused a 29% decrease in HMG-CoA reductase activity and a 56% decrease in cholesterol 7alpha-hydroxylase activity at the diurnal high point. The same chronic ethanol feeding caused a moderate increase in serum cholesterol and a significant increase in hepatic cholesterol concentration. On the basis of these findings, it is suggested that the decreased rate of cholesterol degradation to bile acids may play a significant role in the accumulation of cholesterol in the liver after chronic ethanol feeding.

Alcohol Oxidoreductases↗
PubMed1976

A comparison of the metabolic effects of bovine growth hormone and growth factor from Spirometra mansonoides on rat liver in vivo.

The effects of bovine growth hormone(GH) and Spirometra growth factor (SGF) on the in vivo concentrationions of glycolytic and citricacid (TCA) cycle intermediates in rat liver were investigated. The effects of these agents on the mitochondrial and cytoplasmic redox states, liver phosphorylation states, and adenylate kinase activity were also evaluated. The effects of SGF were studied in both normal and hypophysectomized rats,wheras GH effects ere examined only in hypophysectomized rats. Growth homrone(0.25mg/rat) was injected dayily for 9 days...

Adenine Nucleotides↗