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Biomedical subjects

J H Moore

Publications and source records attributed to J H Moore.

18 recordsLinked to original sources
PubMed1979

Positional distribution of exogenous and endogenous fatty acids in triacylglycerols formed by rat adipocytes in vitro.

Rat adipocytes were used in vitro to compare the positional distributions of fatty acids of intra- and extra-cellular origin in triacyl-sn-glycerols. Fatty acids of extracellular origin were esterified to each position in similar, but not identical, proportions to the natural distributions. A high proportion of the oleic acid synthesised in the tissue by desaturation of exogenous stearic acid was found in position sn-3. When palmitic acid was the only fatty acid added, tripalmitoylglycerol was synthesised by the adipocytes. The rate and pattern of fatty acids synthesised de novo from acetate was dependent on the age of the donor rat and the concentration of acetate and presence or absence of long-chain fatty acids in the medium. The newly synthesised fatty acids were esterified in very different proportions from the natural distributions and thus from those of extracellular fatty acids. The results are discussed in terms of esterification of the fatty acids from the two sources in different compartments of the cell.

Adipose Tissue↗
PubMed1979

Esterification of exogenous and endogenous fatty acids by rat adipocytes in vitro.

Rat adipocytes were used in vivo to compare the esterification of exogenous fatty acids and fatty acids formed de novo from glucose or acetate. Pure single fatty acids added to the medium were esterified at comparable rates but marked differences were observed when the same acids were supplied as components of a fatty acid mixture of a composition similar to that in the tissue. Fatty acids synthesised de novo from acetate by adipocytes in a medium containing high concentrations of acetate were located predominantly in diacylglycerols. The effect was most marked with adipocytes from older rats and was enhanced by the presence of exogenous long-chain fatty acids. Exogenous oleic acid was esterified predominantly into triacylglycerols at all concentrations of acetate. No such accumulation of endogenously-synthesised fatty acids in diacylglycerols occurred when glucose was the precursor for fatty acid synthesis. The diacylglycerols formed were almost entirely of the sn-1,2-configuration.

Acetates↗
PubMed1978

"Protected" polyunsaturated fatty acid in the diet of the ewe and the essential fatty acid status of the neonatal lamb.

A polyunsaturated fatty acid supplement, protected from biohydrogenation in the rumen by a formaldehyde-treated protein coat, was fed to ewes during the last 8 weeks of pregnancy as a possible method of improving the poor essential fatty acid status of the newborn lambs. Significant increases were observed in the concentrations of 18:2 (n-6) in both the cholesteryl ester and phospholipid fractions of the plasma and in the phospholipid fraction of the liver of the lamb at birth. Concomitantly, there were significant increases in 20:4 (n-6) concentrations and reductions in the concentrations of 20:3 (n-9). In addition, the concentration of 18:2 (n-6) in the colostrum of the ewes was increased some eightfold thereby providing a secondary source of this essential fatty acid to the lamb. A marked decrease in erythrocyte fragility was observed in lambs whose ewes had received the "protected" polyunsaturated fatty acid diet. These findings are discussed in relation to the known metabolic roles of essential fatty acids in the animal body, with particular reference to the essential fatty acid status of the lamb at birth.

Animals↗
PubMed1978

Dietary influences on fatty acid metabolism in the liver of the neonatal lamb.

A "protected" polyunsaturated fatty acid supplement was fed to ewes during the last 8 weeks of pregnancy. The effect of this dietary supplement on the essential fatty acid composition of the liver phospholipids and associated changes in the liver delta9- and delta6-desaturase activities were investigated and compared with the effects of directly dosing the newborn lambs for 8 days with an unprotected polyunsaturated oil, maize oil. The maternal dietary supplement produced significant changes in the essential fatty acid composition of the neonatal lamb liver phospholipids. Although the liver delta6-desaturase activity in these animals was also significantly higher than in the lambs from control ewes, the delta9-desaturase was unaffected by maternal dietary supplementation. Direct dosing of the newborn lambs with maize oil failed to produce any signficant changes either in the liver phospholipid fatty acid composition or in the delta9- and delta6-desaturase activities. These results are discussed in terms of the dietary control of liver desaturase enzyme systems.

Animals↗
PubMed1978

In vivo changes in the composition of cattle skin surface lipid with time.

The skin surface lipid composition was examined in cattle over a period of 13 days after cleaning the skin at 15 degrees C and 35 degrees C. Little change was observed in the concentrations and fatty acid compositions of all the major sebum fractions other than the unesterified fatty acids. Changes which occurred in the proportions of fatty acids present in the unesterified fatty acid fraction were similar at both environments. At 15 degrees C the total amounts per unit area of unesterified fatty acids on the skin did not alter significantly with time. However, at 35 degrees C there was a significant increase in the total amounts of unesterified fatty acids per unit area and concomitant increases in the amounts of individual fatty acids, in particular linoleic acid.

Animals↗
PubMed1975

Synthesis of cholesterol esters in the plasma and liver of sheep.

A study was made with sheep on the formation in vitro of long chain fatty acid esters of cholesterol by the lecithin-cholesterol-acyltransferase system present in the plasma and the acyl CoA-cholesterola cyltransferase system present in the liver. The rate of cholesterol esterification in the plasma was 0.024 mumoles/ml/hr. The relative pattern of fatty acids esterified during incubation of the plasma remained constant over the 8 hr period of incubation and was similar to the fatty acids in the plasma cholesteryl esters before incubation began and to the fatty acids in the 2-position of the plasma lecithin. The predominant cholesteryl esters synthesized contained monoenoic and dienoic fatty acids. Unlike the bovine, there was no apparent discrimination in favor of the 18:2 containing species of plasma lecithin as donors of fatty acids. This difference could be accounted for by the similarity in the 18:2 content of the phospholipids present in the high density (density greater than 1.062 and less than 1.21) and the low density (density greater than 1.006 and less than 1.063) lipoprotein fractions of the sheep plasma. The possibility of some discrimination against 20:4 during cholesterol ester synthesis in the plasma of the sheep cannot be excluded. In the liver, the predominant cholesteryl esters synthesized contained saturated and monoenoic fatty acids; cholesteryl linoleate was synthesized to a very much less extent. There was considerable similarity between the composition of the unesterified fatty acid fraction of the liver before incubation began and the fatty acid composition of the cholesteryl esters synthesized during incubation. Addition of sonicated suspensions of free fatty acidsaltered markedly the fatty acid pattern of the cholesteryl esters synthesized by the liver slices. From the evidence presented it is concluded that the cholesteryl esters in sheep plasma are syntheized mainly by the plasma lecithin-cholesterol-acyltransferase system. The results are discussed in relation to cholesterol esterification systems demonstrated in the plasma and liver of monogastric animals.

Animals↗
PubMed1975

Changes with diet in the composition of phosphatidyl choline of sheep bile.

Bile phosphatidyl choline from sheep, in contrast to that from nonruminants, contains low levels of the normal range of polyunsaturated fatty acids. A comparison has been made of the composition of bile phosphatidyl cholines from sheep receiving either a control diet, a control diet supplemented with unprotected maize oil, or a control diet supplemented with soybean oil or tallow that had been protected against hydrolysis and hydrogenation of the rumen. The composition of bile phosphatidyl choline from sheep receiving protected soybean oil supplement was virtually indistinguishable from that from nonruminants.

Animals↗
PubMed1975

Effect of diet on the composition of cholesteryl esters of sheep adrenals.

Fatty acid components of cholesteryl esters from the adrenals of sheep, like those of nonruminants, were characterized by significant amounts of the longer chain metabolites of linoleic acid. Administration to sheep of diets rich in linoleic acid and protected against biohydrogenation did not alter the concentration of these components significantly. Although 18:2 levels were elevated, this was largely at the expense of cis-monoenoic fatty acids.

Adrenal Glands↗
PubMed1975

Relationship between lipids in plasma and skin secretions of neonatal calf with particular reference to linoleic acid.

A study has been made on the lipid composition of the skin secretions and plasma of the neonatal calf. A significant proportion of the skin surface lipids was comprised of triglycerides. Saturated fatty acids comprised the major proportion of the fatty acids of the skin surface triglycerides at birth. Immediately after birth, the proportion of the saturated fatty acids decreased, and there was a concomittant increase in the proportion of 18:1. Some 3-4 weeks after birth, the proportion of 18:2 delta cis-9, cis-12 in the skin surface triglycerides increased to ca. 14 percent, and there was a decrease in the proportion of 18:1. The 18:2 was shown to be confined almost entirely to the 2 position of the triglycerides. During the first 5 weeks after birth, the concentrations of the cholesteryl esters and phospholipids in the plasma increased markedly and were accompanied by a rapid increase in the proportion of 18:2 within these 2 fractions. The results are discussed in relation to the known role of 18:2 in the metabolism of biological systems.

Animals↗
PubMed1975

The role of plant particles, bacteria and cell-free supernatant fractions of rumen contents in the hydrolysis of trilinolein and the subsequent hydrogenation of linoleic acid.

The role of different fractions of rumen contents in the hydrolysis of trilinolein and the subsequent hydrogenation of the linoleic acid has been investigated by a series of in vitro incubations. Hydrolysis of the trilinolein to free linoleic acid occurs almost wholly in the cell-free supernatant; the liberated linoleic acid in the supernatant can be rapidly adsorbed onto food particles where it is hydrogenated to stearic acid via the C18 trans-11 monoene. Some 25% of the trilinolein added as substrate was taken up by the bacteria and of this a small percentage appeared to be hydrolysed and the free linoleic acid hydrogenated to stearic acid intracellularly. No conclusive evidence was obtained to suggest that this intracellular hydrogenation proceeded by a route other than that which took place on the food particles.

Animals↗
PubMed1975

Plasma cholesterol ester formation in the neonatal lamb.

Investigations have been made into the activity of the lecithin-cholesterol-acyltransferase (LCAT) enzyme in the formation of the cholesteryl esters in the plasma of the newborn lamb. Although LCAT activity is present in the plasma immediately after birth, within 24 h a large increase in the activity of the LCAT system occurs. This increase in LCAT activity during the first 24 h after birth is associated with increased concentrations of lipid substrates in the plasma. However, evidence is provided to show that severe inhibition occurs in the relative efficiency with which the LCAT mechanism operates in the plasma of the lamb immediately after birth.

Acyltransferases↗