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Biomedical subjects

A Mazur

Publications and source records attributed to A Mazur.

At least 145 records · Page 8Linked to original sources
PubMed1991

Magnesium deficiency affects plasma lipoprotein composition in rats.

Weanling rats were pair-fed for 8 d with control and Mg-deficient diets containing 960 and 30 mg of Mg/kg, respectively. The marked reduction in plasma Mg levels indicated that the rats fed the Mg-deficient diet were indeed deficient. In the Mg-deficient rats the percent composition of triglycerides in VLDL, LDL and HDL was elevated and that of protein was reduced. Although the proportion of cholesterol was reduced in LDL and HDL, that of phospholipid was decreased only in HDL. Magnesium deficiency induced a decrease in the percent composition of apolipoprotein (apo) E and a relative increase in the apo C for VLDL. In HDL from Mg-deficient rats, the proportion of apo AI was higher than normal, apo AIV was lower than normal and apo E was virtually absent. The percent composition of oleic and linoleic acids was increased but that of stearic and arachidonic acids was depressed in both VLDL and HDL derived from Mg-deficient rats compared with pair-fed controls. Whether these alterations in lipoprotein profile contribute to hyperlipoproteinemia or are the results of the metabolic changes that produce hyperlipoproteinemia remain to be determined.

Animals↗
PubMed1991

Developmental changes in plasma apolipoproteins B and A-I in fetal bovines.

Plasma lipid, apolipoprotein (apo) B and apo A-I concentrations were measured in fetal calves in the age range of 4-9 months. The results were compared with those obtained from preruminant calves and cows. The studied lipids and apolipoproteins underwent quantitative underwent quantitative changes during development. Fetal calves, as compared to preruminant calves and cows, had a particularly low apo A-I concentration and a high apo B/apo A-I ratio. Unlike adult animals which have two forms of apo B, fetal calves had only high molecular weight apo B (apo Bh). During fetal development triglyceride, cholesterol and apo B concentrations decreased, but apo A-I concentrations remained constant.

Aging↗
PubMed1990

Serum apolipoproteins B and A-I and naturally occurring fatty liver in dairy cows.

Serum lipids and apolipoprotein (apo) B and A-I concentrations were determined in 164 dairy cows which had undergone liver biopsy in early lactation. The animals were divided into groups according to fatty liver severity on the basis of hepatic triglyceride content. The serum free fatty acid (FFA) concentration was higher in cows that developed fatty livers than in normal cows, and it correlated highly with liver triglycerides. Serum total cholesterol and triglyceride levels did not correlate with hepatic triglycerides. Both apo B and apo A-I levels were significantly decreased in fatty liver cows. In particular, apo B levels showed a strongly negative correlation with liver triglycerides. The present results suggest that hepatic apolipoprotein synthesis is impeded in fatty liver cows.

Animals↗
PubMed1990

Effects of diets rich in fermentable carbohydrates on plasma lipoprotein levels and on lipoprotein catabolism in rats.

This study was conducted to examine the effects of a combination of several dietary fibers (5% guar gum, 5% apple pectin, 15% wheat bran, 22% soybean fiber) and crude potato starch (23%) on plasma lipids and lipoproteins and on liver lipid concentration in rats fed a diet containing either 15% lard or 5% oil with or without dietary cholesterol/cholic acid. Male Wistar rats ate the test diets for 3 wk. The incorporation of fiber and crude potato starch into the diet resulted in a significant enlargement of the cecum; it also increased the concentration of volatile fatty acids and the pool of acetate, propionate and butyrate. Feeding this fermentable carbohydrate decreased plasma cholesterol and triglyceride levels in rats given a low fat diet and prevented the expected rise in plasma cholesterol and triglycerides in rats fed cholesterol/cholic acid or lard. Further studies of high density lipoprotein (HDL) composition, 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMG-CoA reductase) activity and 125I-labeled human low density lipoprotein (LDL) turnover were done in the group fed the low fat diet without added cholesterol/cholic acid. The study of the HDL fraction in rats fed a diet rich in fermentable carbohydrates demonstrated a decrease in the HDL1 subpopulation and in the proportion of apolipoprotein E. Plasma clearance of intravenously injected 125I-labeled LDL was faster in rats fed this diet than in rats fed the fiber-free diet. In the liver, cholesterol and triglyceride levels were depressed whereas the activity of HMG-CoA reductase was increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The effect of high-fibre diet on plasma lipoproteins and hormones in genetically obese Zucker rats.

The effects of prolonged substitution of readily digested carbohydrates (wheat starch) for poorly digested carbohydrates (mixture of various fibres and crude potato starch) on plasma lipids, lipoproteins and hormones were investigated in Zucker, genetically obese rats. Lean rats were also studied in parallel. Usually, plasma lipid and insulin levels and insulin/glucose ratio were higher in obese rats vs. their lean littermates. High-fibre diet intake led to weight loss in both obese and lean rats. With a high-fibre diet, plasma lipid, insulin and glucose postprandial levels in both groups were reduced when compared with their respective control animals. Dietary fibre modified the lipoprotein profile. Triglycerides and cholesterol were reduced in all studied lipoprotein fractions. The study of high density lipoprotein (HDL) fraction in rats fed a high-fibre diet demonstrated a decrease in the HDL1 subpopulation and in the apolipoprotein (apo)E proportion. The findings show that a high-fibre diet modulates plasma lipid, insulin and glucose levels and modifies the plasma lipoprotein distribution and composition in normolipaemic, lean rats as well as in hyperlipaemic, genetically obese rats.

Animals↗
PubMed1989

Plasma lipoproteins in dairy cows with naturally occurring severe fatty liver: evidence of alteration in the distribution of apo A-I-containing lipoproteins.

The relationships between fatty liver in dairy cows and reduced levels of plasma lipoproteins, and particularly of low density lipoproteins (LDL), has been previously described. Since electrophoretic heterogeneity of ultracentrifugally isolated LDL (d, 1.006-1.063 g/ml) has been found, the exact nature of this reduction in cows with fatty liver was investigated. Lipoproteins from control and severely afflicted animals were isolated by ultracentrifugation and affinity chromatography on heparin-Sepharose CL 6 B. Gradient gel electrophoresis of lipoproteins on 4-30% gels and an immunolocalization study of apoprotein A-I (apo A-I) showed that control animals have two subpopulations of apo A-I-containing particles with a mean radius of 6.52 and 5.05 nm. In the fatty liver cows, the former was clearly shifted toward smaller particles. We concluded that the depressed level and compositional modifications of LDL in severe fatty liver cows result from a decrease in the oversized apo A-I-containing lipoproteins which can be isolated in the LDL density range. This could stem from the decreased supply of triglyceride-rich lipoprotein surface components for the production of these lipoproteins. The modifications can be plausibly explained by a reduced synthesis or secretion of very low density lipoproteins (VLDL) by the liver.

Animals↗
PubMed1989

Testosterone, and winning and losing in human competition.

Testosterone and cortisol were measured in six university tennis players across six matches during their varsity season. Testosterone rose just before most matches, and players with the highest prematch testosterone had the most positive improvement in mood before their matches. After matches, mean testosterone rose for winners relative to losers, especially for winners with very positive moods after their victories and who evaluated their own performance highly. Winners with rising testosterone had higher testosterone before their next match, in contrast to losers with falling testosterone, who had lower testosterone before their next match. Cortisol was not related to winning or losing, but it was related to seed (top players having low cortisol), and cortisol generally declined as the season progressed. These results are consistent with a biosocial theory of status.

Achievement↗
PubMed1989

Quantitative determination of apolipoprotein B in bovine serum by radial immunodiffusion.

1. In the present study we describe the first quantitative determination of apolipoprotein B (apo B) in bovine serum. 2. Immunosera and standard for radial immunodiffusion assay were raised using a purified apo B-containing lipoprotein obtained by ultracentrifugation and affinity chromatography. The assay working range was linear over the concentration of 4-70 mg/100 ml of protein of apo B standard. 3. Contrary to humans, bovine serum contains a low level of apo B-containing lipoproteins. The mean level of apo B in serum samples from cows at various stages of lactation was 16.0 +/- 0.6 mg/100 ml.

Animals↗
PubMed1989

Quantification of apolipoprotein A-1 in cow serum by single radial immunodiffusion.

A single radial immunodiffusion assay was developed to determine the concentration of the major apolipoprotein A-I in bovine serum. Assay was performed using agarose gel plates with monospecific rabbit antiserum. Standards made with bovine high density lipoproteins or serum 10 times diluted were applied in 3-microliters amounts to each well in the gel. The assay working range was 2 to 22 mg of apolipoprotein A-I. The intraassay and interassay CV were 3.7 and 4.9%, respectively. Using protein A-I. The intraassay and interassay CY were 3.7 and 4.9%, respectively. Using radial immunodiffusion assay, 23 serum samples from cows at various stages of lactation were analyzed. Apolipoprotein A-I was significantly increased in midlactation compared with concentrations in early lactation or dry period.

Animals↗
PubMed1989

Plasma and red blood cell magnesium concentrations in Zucker rats: influence of a high fibre diet.

Because of the possible influence of obesity and insulin levels on magnesium metabolism, we have examined plasma and red blood cell (RBC) Mg in Zucker rats. There were reduced plasma and RBC Mg levels in Zucker rats compared with Wistar rats, and phenotype differences in Zucker rats. In obese rats, a high fibre diet reduced body weight, hyperinsulinaemia and hyperlipaemia and returned the plasma Mg concentration toward normal. However RBC levels were significantly lower than in lean rats of the same strain. The significance of the altered Mg concentration in obese Zucker rats may have metabolic implications and needs further study.

Animals↗
PubMed1988

Plasma lipoproteins and fatty liver in dairy cows.

Dairy cows were classified on the basis of a histological study after a hepatic biopsy conducted in the second week post partum (mild fatty liver, moderate fatty liver, severe fatty liver). Plasma lipoproteins were separated into various density classes by repeated ultracentrifugation. The results indicate that the beginning of lactation is associated with a low concentration of the 1.006 to 1.063 g ml-1 lipoprotein fraction. The lowest concentrations occurred in cows with severe steatosis or during the evolution of moderate steatosis.

Animals↗
PubMed1988

[Lipoprotein profile of the lactating cow].

The profile of serum lipoproteins in the dairy cow in the 8th week of lactation was studied with different techniques: sequential ultracentrifugation, selective precipitation, gel filtration. The dairy cow has characteristically low levels of triglycerides and VLDL (d less than 1.006 g/ml). Most of the circulating lipids are related to HDL (d = 1.063-1.21 g/ml). The fraction that corresponds to LDL (d = 1.006-1.063 g/ml) has some features of alpha and beta lipoproteins. An electrophoretic study of fractions isolated by agarose gel filtration shows a progressive alpha and beta mobility transition between LDL and HDL. This study demonstrates that the density interval 1.006-1.063 g/ml contains LDL and "light" HDL.

Animals↗