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Biomedical subjects

R G Vernon

Publications and source records attributed to R G Vernon.

At least 145 records · Page 8Linked to original sources
PubMed1979

Role of insulin receptors in the changing metabolism of adipose tissue during pregnancy and lactation in the rat.

Changes in the volume, the rates of fatty acid synthesis and synthesis of the glycerol moiety of acylglycerols, the activity of lipoprotein lipase, and the number and affinity of insulin receptors of adipocytes, and concentrations of serum insulin, prolactin and progesterone were determined in virgin rats and in rats at various stages of pregnancy and lactation. Changes in the metabolic activities of adipose tissue appeared to be synchronized and primarily comprised a marked decrease in anabolic activity around parturition. In contrast, the number of insulin receptors (Kd 1.5 nM) per adipocyte doubled during pregnancy before returning to normal values around parturition. It is postulated that the increase in the number of insulin receptors is an adaptation to counteract the effects of insulin-antagonistic hormones during pregnancy and that the decrease in the number of receptors is primarily responsible for the loss of anabolic activity around parturition.

Adipose Tissue↗
PubMed1977

Development of perirenal adipose tissue in the neonatal lamb: effects of dietary safflower oil.

Perirenal adipose tissue development was investigated in lambs from birth until 17 days of age. Changes in the morphology, the lipid, protein, RNA and DNA content, the adipocyte number and size, and the rate of protein, RNA and DNA synthesis of the perirenal fat-pads are reported. During the first 9 days after birth the tissue lost the morphological characteristics of brown adipose tissue and acquired those of white adipose tissue. As there was no change in either the number of adipocytes or the DNA content of the fat-pads between birth and 9 days of age it is concluded that there was a differentiation of brown into white adipocytes. Over 80% of the increase in tissue weight between birth and 17 days of age was due to lipid deposition. Administration of safflower oil to the lambs had no apparent effect on the change from brown to white fat, but it markedly reduced the rate of lipid deposition between days 9 and 17 post partum.

Adipose Tissue↗
PubMed1976

Triacylglycerol biosynthesis in rat adipose-tissue homogenates.

The optimum cofactor requirements for triacylglycerol biosynthesis in rat adipose-tissue homogenates containing mitochondrial, microsomal and cytosolic fractions were investigated. In general the optimum concentrations of cofactors for triacylglycerol biosynthesis were found to differ from those for total fatty acid esterification. The results provided further evidence for the key role of phosphatidate phosphohydrolase in the regulation of triacylglycerol biosynthesis. Albumin was included in the incubation medium to permit the use of concentrations of added fatty acids that would swamp the effects of endogenous fatty acids. The addition of albumin had little effect on the incorporation of palmitic acid and stearic acid into lipids including triacylglycerols. By contrast, a critical concentration of albumin (about 60 muM) was required before incorporation of oleic acid or linoleic acid into triacylglycerols occurred. The system was used to study the incorporation of different 1-14C-labelled fatty acids from a mixture of unesterified fatty acids [palmitic acid 30%; stearic acid 10%; oleic acid 40%; linoleic acid 20% (molar percentages)] separately into the positions 1,2 and 3 of triacyl-sn-glycerols. In general the stereo-specific distribution of the labelled fatty acids incorporated into triacylglycerols paralleled the normal distribution of fatty acids within rat adipose-tissue triacylglycerols, suggesting that the specificities of the relevant acyltrasferases have the major role in determining the positional distribution of fatty acids within triacylglycerols.

Adipose Tissue↗
PubMed1976

Effect of dietary fats on ovine adipose tissue metabolism.

The effects of different dietary fats on ovine adipose tissue metabolism have been investigated. Six-month old sheep were fed for 6 weeks a control diet or diets supplemented with either tallow or a mixture of sunflower seed oil and soybean oil, treated to protect the fats from hydrolysis and hydrogenation in the rumen, or with maize oil. The rates of fatty acid, glyceride glycerol, and CO2 formation were measured in perirenal and subcutaneous adipose tissue slices by following the incorporation of either 14C from labeled acetate or glucose, or 3H from tritiated water into the appropriate product. Feeding protected tallow or maize oil but not protected sunflower seed oil plus soybean oil resulted in reduced rates of fatty acid biosynthesis in both perirenal and subcutaneous adipose tissue slices and CO2 formation in perirenal adipose tissue. Feeding the fat-supplemented diets had no effect on the rate of glyceride glycerol formation. The fat-supplemented diets also resulted in reduced activities of various enzymes, thought to be involved in lipogenesis, measured in 105,000 x g supernatant fractions from adipose tissue homogenates. The results suggested that ovine adipose tissue lipogenesis is sensitive to both the amount and the nature of dietary fat.

Acetate-CoA Ligase↗
PubMed1975

Effect of dietary safflower oil upon lipogenesis in neonatal lamb.

The effect of dietary safflower oil upon lipogenesis has been investigated in neonatal lambs. Preliminary experiments with lambs suckled by their mothers showed that there was a 10-fold increase in the rate of incorporation of [14-C] from acetate into fatty acids in adipose tissue slices during the first 10 days post partum. Barely detectable rates of [14-C] acetate incorporation into fatty acids were found in liver slices from lambs during the same period. In lambs given cows' milk from birth untill 11 days of age, there was also a 10-fold increase in the rate of lipogenesis in adipose tissue slices. Supplementing the diet of cows' milk with safflower oil (5 ml/lamb/day) resulted in significantly lower rates of lipogenesis in adipose tissue slices from 11 day old lambs. Administration of safflower oil had no effect upon the concentration of unesterified fatty acids, including linoleic acid, in the lamb adipose tissue slices. The data show that lipogenesis in ovine adipose tissue, like that in rodent liver and adipose tissue, is sensitive to dietary polyunsaturated fatty acids, and that, for the neonatal lamb, the effect of polyunsaturated fatty acids upon lipogenesis is not dependent upon an increase in the tissue concentration of polyunsaturated fatty acids.

Acetates↗
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↗