Harriet C Beckenhauer

Learn More
BACKGROUND/AIMS Previous studies in our laboratory implicated ethanol-induced decreases in hepatocellular S-adenosylmethionine to S-adenosylhomocysteine (SAM:SAH) ratios in lowering the activity of phosphatidylethanolamine methyltransferase (PEMT), which is associated with the generation of steatosis. Further in vitro studies showed that betaine(More)
Previous studies from our laboratory have shown that ethanol consumption results in an increase in hepatocellular S-adenosylhomocysteine levels. Because S-adenosylhomocysteine is a potent inhibitor of methylation reactions, we propose that increased intracellular S-adenosylhomocysteine levels could be a major contributor to ethanol-induced pathologies. To(More)
Two of the most important biochemical hepatic pathways in the liver are those that synthesize methionine and S-adenosylmethionine (SAM) through the methylation of homocysteine. This article reviews some recent findings in this laboratory, which demonstrate that ethanol feeding to rats impairs one of these pathways involving the enzyme methionine synthetase(More)
Pairs of rats were fed control and alcohol liquid diets for periods of 1, 2, 3, and 4 months. The animals were then killed, and their livers analyzed for betaine, S-adenosylmethionine (SAM), methionine synthetase activity, and betaine--homocysteine methyltransferase (BHMT) activity. The results of this time-course study showed that chronic ethanol feeding(More)
Previous studies have shown that ethanol feeding to rats alters methionine metabolism by decreasing the activity of methionine synthetase. This is the enzyme that converts homocysteine in the presence of vitamin B12 and N5-methyltetrahydrofolate to methionine. The action of the ethanol results in an increase in the hepatic level of the substrate(More)
Previous studies showed that chronic ethanol administration inhibits methionine synthase activity, resulting in impaired homocysteine remethylation to form methionine. This defect in homocysteine remethylation was shown to increase plasma homocysteine and to interfere with the production of hepatic S-adenosylmethionine (SAM) in ethanol-fed rats. These(More)
The feeding of ethanol to experimental animals results in fatty infiltration of the liver. Recent findings have shown that ethanol-induced steatosis is accompanied by a lowering in hepatic S-adenosylmethionine (SAM) levels. It is known that SAM provides substrates for reduced glutathione formation and offers the cell protection from toxic metabolic(More)
One of the most important biochemical pathways in the organism is the biosynthesis of methionine from the methylation of homocysteine. Two different reactions are responsible for this methylation, one utilizing N5-methyltetra-hydrofolate as a methylating agent and the other using betaine as the methyl donor. This paper reviews some recent findings in this(More)
Results of previous studies have shown that chronic ethanol administration impairs methionine synthetase activity and decreases S-adenosylmethionine levels in the liver, indicating interference with homocysteine remethylation. The purpose of the present study was to investigate the effects of chronic ethanol feeding on the accumulation of homocysteine(More)
Previous studies showed that chronic ethanol administration alters methionine metabolism in the liver, resulting in increased intracellular S-adenosylhomocysteine (SAH) levels and increased homocysteine release into the plasma. We showed further that these changes appear to be reversed by betaine administration. This study compared the effects of betaine(More)