PubMed Health⌕ Search

Biomedical subjects

R C Reitz

Publications and source records attributed to R C Reitz.

53 records · Page 3Linked to original sources
PubMed1978

Arachidonic acid and other free fatty acid changes during abortion induced by prostaglandin F2alpha.

Serum free fatty acids (FFA's) were measured after intra-amniotic injection of prostaglandin F2alpha (PGF2alpha) for the induction of abortion in eight healthy women in the midtrimester of pregnancy. The total FFA levels increased in all cases during the period between PGF2alpha administration and abortion. This lipolysis most likely is secondary to the effect of the catecholamines as indicated by the temporal relationship between increased plasma and urine catecholamine and serum FFA levels. The percentage of arachidonic acid in the total amount of FFA's decreased after administration of PGF2alpha. This proportional decrease in arachidonic acid (p less than 0.05) may be due to selective utilization for the production of endogenous prostaglandins.

Abortion, Induced↗
PubMed1977

Mitochondrial and microsomal phospholipids of Morris hepatoma 7777.

The phospholipids of both mitochondrial and microsomal membranes from normal liver, host liver, and Morris hepatoma 7777 were isolated, separated, and quantitated. The total as well as the individual fatty acid concentrations and compositions were determined. The total phosphlipids isolated from tumor mitochondria were idly altered, compared with mitochondria from other normal or host liver. The polyenoic acids were decreased, and there was a concomitant increase in the monoenes. When the respiratory control was determined, the tumor mitochondria exhibited a significant decrease in this parameter. The tumor microsomal membrane fraction, on the other hand, contained about 50% less phospholipid than the controls. The fatty acid patterns of the total as well as the individual phospholipids were quite similar to those observed in the mitochondria. The species of phosphatidylcholine from both membrane fractions were separated by argentation chromatography of the intact molecules, and, as predicted by the fatty acid compositions, the major species of the tumor was the monoenoic/dienoic fraction. The acyl coenzyme A:1-acyl glycerophosphorylcholine acyltransferases, which aid in controlling the fatty acid composition of phospholipids, were measured. The very marked increase in activity of these enzymes toward polyenoic as well as monoenic fatty acids suggested that the polyenoic acids were not available for use in the resynthesis of the phosphatidylcholines in the tumor.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1975

Studies on the mechanism of the NADPH-catalyzed peroxidation of endogenous microsomal lipid.

The importance of metal chelation in the mechanism of microsomal lipid peroxidation has been studied using both phosphate- and sulfhydryl-containing compounds. The optimal concentration for maximum stimulation by each of these compounds has been determined, and the decrease in stimulation observe at concentrations above the maxima has been related to the ability of these compounds to form stable chelation complexes with non-heme iron. Of the compounds tested, only ADP and ATP facilitated the cooperative binding of NADPH to the membrane and thus suggested the possibility of three binding sites for NADPH. Neither of the other two phosphate-chelating agents (Pi or PPi) and neither of the two thiols (cysteine or dithiothreitol)facilitated cooperative binding of NADPH. These data suggested that the adenine ring of ADP or ATP is directly involved in the cooperativity of NADPH binding. They also emphasized that the binding of the chelation complex to the protein is an important parameter in the mechanism of the NADPH-catalyzed peroxidation of endogenous microsomal lipids. Furthermore, stimulation of the rat of lipid peroxidation by sulhydryl-containing compounds, by freezing thawing the microsomal protein, and by treatment of the protein with detergent may be due to a decrease in this cooperative binding effect. Since cysteine and deoxycholate as well as freezing and thawing alter membrane structure, the stimulation of lipid peroxidation seems to involve some alteration to the structure of the microsomal membrane prior to the onset of enzymatic lipid peroxidation.

Adenosine Diphosphate↗
PubMed1975

A possible mechanism for the peroxidation of lipids due to chronic ethanol ingestion.

The effects of chronic ethanol ingestion on NADPH-oxidase and on the NADPH-catalyzed peroxidation of lipids in rat liver microsomes have been studied. It was demonstrated that the rates of NADPH oxidation, of oxygen consumption, and of malondialdehyde formation increased significantly above control values after one month of ethanol ingestion. Further, the fatty acid composition of these microsomes revealed a decrease in arachidonate and in the C22 polyenes. Also, the energies of activation for the formation of malondialdehyde increased in the microsomes from the ethanol-treated animals. These results were interpreted to mean that ethanol ingestion had induced changes in the microsomal membranes such that additional or alternate, possibly abnormal, pathways for lipid peroxidation were functional. Finally, these data suggest a mechanism whereby chronic ethanol ingestion inhances the production of lipid peroxides via the microsomal-catalyzed oxidation of NADPH.

Aldehydes↗
PubMed1974

Growth inhibition among strains of Neisseria gonorrhoeae due to production of inhibitory free fatty acids and lysophosphatidylethanolamine: absence of bacteriocins.

Each of 50 tested strains of Neisseria gonorrhoeae produced growth-inhibitory substances that were active against most strains of gonococci or meningococci, but not against species other than the Neisseria. There were quantitative differences among different strains in production of the inhibitor and sensitivity to it, but not of sufficient magnitude to permit routine strain typing. The inhibitor was associated with the cell pellet (crude cell envelope) and was not inducible with mitomycin C. Inhibitory activity was thermostable and resisted alkali and proteolytic enzymes. The inhibitor was quantitatively recovered from whole cells by chloroform-methanol extraction. Separation of total gonococcal lipids by silica gel chromatography revealed inhibitory activity in both the free fatty acid and the phospholipid fractions. The major phospholipid, phosphatidylethanolamine, had no inhibitory activity, but monoacyl phosphatidylethanolamine, a minor phospholipid, was quite inhibitory. It is likely that the "bacteriocin" of N. gonorrhoeae strains results from the degradation of phosphatidylethanolamine to inhibitory long-chain free fatty acids and monoacyl phosphatidylethanolamine.

Bacteriocins↗
PubMedDate not supplied

Effects of chronic ethanol ingestion on male and female rat liver glycogen phosphorylase phosphatase.

The effects of chronic ethanol ingestion on the interconversion of the active to the inactive form of glycogen phosphorylase by phosphorylase phosphatase was studied. Male and female rats also were compared. Chronic ethanol feeding decreased phosphorylase a and total phosphorylase activity in male rats. In females, no change was observed in phosphorylase a, whereas total phosphorylase activity was increased 73%. This was found to correlate with the relative activities of phosphorylase phosphatase. The data show differences between the two sexes with regard to the AMP inhibition of phosphorylase phosphatase and the caffeine stimulation of the phosphatase. Ethanol markedly enhanced the AMP inhibition of the phosphatase in males but had no effect in females. Further studies in females showed that ethanol completely obliterated the well documented stimulation of the phosphatase by caffeine; however, it did not alter the caffeine effect in males. These data suggest possible alterations in the tertiary structure of phosphorylase a.

Adenosine Monophosphate↗