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PubMed1979

[Study of lipid dependence of glucose-6-phosphatase from rat liver and hepatoma using lipid exchange proteins].

In order to study the lipid dependence of glucose-6-phosphatase the lipid composition of microsomes from rat liver and hepatoma was modified using lipid exchange proteins. It was shown that the enzyme activity depends on the presence of phosphatidyl ethanolamine and phosphatidyl serine, but is unaffected by the enrichment of the microsomes with phosphatidyl choline. On the basis of the data obtained it was assumed that the aminophospholipids are required for the functioning of the protein carrier; however, they do not affect the activity of the catalytic component of the glucose-6-phosphatase system on the inner surface of the microsomal membrane.

Animals↗

PubMed1988

Effects of long-term physical exercise on serum lipids, lipoproteins and lipid metabolizing enzymes in type 2 (non-insulin-dependent) diabetic patients.

The effects of four months' physical exercise on serum lipids, lipoproteins and lipid metabolizing enzymes were studied in 25 non-insulin-dependent diabetic patients divided randomly into exercise (n = 13) and control (n = 12) groups. Exercise induced a significant decrease in serum LDL-cholesterol and an increase in serum HDL-cholesterol and HDL2-cholesterol. Triglycerides showed a temporary decrease. Apoproteins A1 and B were virtually unchanged. Postheparin plasma lipoprotein lipase increased markedly during the exercise period while no change occurred in adipose tissue lipoprotein lipase, hepatic lipase or lecithin:cholesterol acyltransferase. In the control group no significant changes occurred in any of the lipid variables. In the light of the knowledge of LDL-cholesterol as a causative and HDL-cholesterol as a protective factor in atherogenesis in non-diabetics the changes caused by exercise in non-insulin-dependent diabetics can be considered favourable.

Adipose Tissue↗

PubMed1980

The biosynthesis of oligosaccharide-lipids. Isolation of an oligosaccharide-P-P-lipid acceptor.

An oligosaccharide-P-P-lipid has been isolated from porcine liver by extraction with organic solvents and purified by chromatography on silica gel and DEAE-cellulose. The purified oligosaccharide-lipid was shown to contain mannose and N-acetylglucosamine in an approximate ratio of 1:1 and our results suggest that the major oligosaccharide component in the preparation was a tetrasaccharide with the composition (Man)2 (GlcNAc)2. When the oligosaccharide-lipid was incubated with GDP-[14C]mannose and a solubilized enzyme preparation from rabbit liver in the presence of MgCl2, three radioactive products could be isolated. The oligosaccharides in the products could be identified as a penta-, a hexa-, and a heptasaccharide. These products were formed by the stepwise addition of mannose to the growing oligosaccharide chain and GDP-mannose was indicated as the glycosyl donor in each reaction.

Animals↗

PubMed1978

[Use of lipid exchange proteins for investigation of lipid dependence of rat liver cytochrome P-450].

The ability of lipid exchange proteins to introduce foreign phospholipids into intact microsomes was used for a study of the lipid dependence of rat liver cytochrome P-450. Cytochrome P-450 was converted into inactive cytochrome P-420 by treatment of rat liver microsomes with lysophosphatidylcholine. When such microsomes were incubated with phosphatidylcholine in the presence of lipid exchange proteins the lysophosphatidylcholine was partly replaced by phosphatidylcholine and the inactive cytochrome P-450 was reactivated. Similar incubation of the inactivated microsomes with phosphatidylethanolamine did not lead to reactivation of the enzyme.

Animals↗

PubMed1983

Familial aggregation of lipids and lipoproteins and early identification of dyslipoproteinemia. The Collaborative Lipid Research Clinics Family Study.

We examined the hypothesis that familial aggregation of lipids and lipoproteins facilitates within-family identification and hyperlipoproteinemia. We studied 841 offspring and 1,236 siblings of normocholesterolemic probands, 833 offspring and 1,194 siblings of hypercholesterolemic probands, 806 offspring and 1,099 siblings of normotriglyceridemic probands, and 877 offspring and 1,108 siblings of hypertriglyceridemic probands in the Lipid Research Clinics Collaborative Family Study Program. As the categorization of probands' hypercholesterolemia or hypertriglyceridemia increased from sporadic, to persistent, to severe, the percentage of hypercholesterolemic or hypertriglyceridemic offspring and siblings increased. Close sibling and parent-offspring lipid and lipoprotein risk factor associations in hypercholesterolemic and hypertriglyceridemic family units during and after the period of shared common-household environment facilitate within-family identification of dyslipoproteinemia and suggest potential sharing of coronary heart disease risk.

Cholesterol↗

PubMed1981

Alcohol intake, cigarette smoking and plasma lipids and lipoproteins in 12--19-year-old children. The Collaborative Lipid Research Clinics Prevalence Study.

The relationship of alcohol intake to plasma lipids and lipoproteins was assessed in 1603 white children, ages 12-19 years, from six Lipid Research Clinics as part of the Lipid Research Clinics Collaborative Population Studies. Of the 1603 children, 933 came from a randomly recalled group and 660 from a group recalled because of elevated cholesterol or triglyceride or both (the hyperlipidemic recall group). Using multiple regression analysis, the relationships of lipoproteins (as dependent variables) to alcohol, smoking, age and body mass (as explanatory variables) are assessed in both recall groups. In the random recall group, high-density lipoprotein (HDL) cholesterol was positively related to alcohol intake, independent of the other variables considered; for every ounce of alcohol intake, HDL cholesterol was 0.55 mg/dl higher in males and 1.04 mg/dl higher in females. HDL cholesterol was strongly and inversely related to smoking and body mass in both males and females and was inversely related to age in males. In females, plasma low-density lipoprotein (LDL) cholesterol, triglycerides and very low density lipoprotein (VLDL) cholesterol were all positively related to alcohol intake. In the hyperlipidemic recall group of children, alcohol intake had a weak positive relationship with HDL cholesterol in males; in the females, for every ounce of alcohol intake, HDL cholesterol was higher by 1.5 mg/dl. Alcohol intake was positively related to triglyceride levels in hypertriglyceridemic male children. In each recall group, alcohol intake had a small, significant, positive association with HDL cholesterol levels in 12--19-year-old children, and a less consistent positive association with triglyceride and VLDL cholesterol. If low HDL cholesterol concentrations in children are undesirable, attention should first be focused reduction of smoking (inversely associated with HDL cholesterol) and weight (inversely associated with HDL cholesterol, positively associated with LDL cholesterol, triglyceride and VLDL cholesterol), as measures that may modify HDL cholesterol levels.

Adolescent↗

PubMed1998

Effects of taurine supplementation on lipid peroxidation, blood glucose and blood lipid metabolism in streptozotocin-induced diabetic rats.

The purpose of this study was to determine the effect of taurine on several complications of diabetes, including oxidative stress, glucose intolerance and blood lipid profile. Sprague Dawley male rats were fed an experimental diet for 7 weeks, at which time they were maintained on drinking water with or without 1% taurine. The experimental period was 7 weeks and the rats were administered streptozotocin (STZ) to induce diabetes. Thiobarbituric acid reactive substances (TBARS) content was increased following the STZ injection, but was lowered by prior treatment with taurine. The primary diabetic symptoms, such as polydipsia and polyuria, were ameliorated in rats supplemented with taurine before the STZ injection. Plasma triglyceride (TG) levels of the diabetic group were decreased by taurine supplementation, although plasma total cholesterol (T-chol) and HDL cholesterol (HDL-chol) were not different among the groups. LDL cholesterol (LDL-chol) levels of the control group were significantly decreased by taurine supplementation, however, the time of taurine administration affected the response of the diabetic group; only diabetic rats treated with taurine after the administration of STZ showed a decrease in LDL cholesterol. Therefore, taurine inhibits lipid peroxidation and decreases blood TG and LDL-chol levels, however, the time and dose of taurine supplementation are variables that need to be considered in the treatment of diabetes.

Animals↗

PubMed1975

[Nutrition physiological aspects of deep frying fats. 7. Effect of deep frying fats on the lipid metabolism and the fatty acid composition of body lipids].

In feeding experiments no differences could be observed when used frying fats were fed to rats in the same amount and over the same period if compared with the unheated fats (partially hardened groundnut oil, soyabean oil). In details we investigated: concentration of plasma lipids, including content of total cholesterol, electrophoresis of plasma lipoproteins, fatty acid composition of plasma lipids and of adipose tissue. Amount and composition of the unsaponifiable matter in heated and unheated fats as well as the content of polycyclic aromatic hydrocarbons were determined. In in-vitro experiments we investigated the effect of pancreas lipase on these fats.

Animals↗

PubMed2000

A pathway model of lipid metabolism to predict the effect of genetic variability on lipid levels.

Complex phenotypes such as serum lipid concentrations involve numerous genes and require the analysis of the combined effects of these gene products. We modeled the interactions of six key lipid metabolism genes by means of differential equations. We tested the model by inserting the effects of known mutations in the low-density lipoprotein receptor gene and the lipoprotein lipase gene, as well as the effects of a high-fat diet, and observed that the predictions corresponded very well to published measurements. Models such as the one that we present here will become indispensable for analyzing and understanding the effects of variation in multiple genes.

Carrier Proteins↗

PubMed2000

Lipid metabolism and tissue composition in Atlantic salmon (Salmo salar L.)--effects of capelin oil, palm oil, and oleic acid-enriched sunflower oil as dietary lipid sources.

Triplicate groups of Atlantic salmon (Salmo salar L.) were fed four diets containing different oils as the sole lipid source, i.e., capelin oil, oleic acid-enriched sunflower oil, a 1:1 (w/w) mixture of capelin oil and oleic acid-enriched sunflower oil, and palm oil (PO). The beta-oxidation capacity, protein utilization, digestibility of dietary fatty acids and fatty acid composition of lipoproteins, plasma, liver, belly flap, red and white muscle were measured. Further, the lipid class and protein levels in the lipoproteins were analyzed. The different dietary fatty acid compositions did not significantly affect protein utilization or beta-oxidation capacity in red muscle. The levels of total cholesterol, triacylglycerols, and protein in very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL), and plasma were not significantly affected by the dietary fatty acids. VLDL, LDL, and HDL fatty acid compositions were decreasingly affected by dietary fatty acid composition. Dietary fatty acid composition significantly affected both the relative fatty acid composition and the amount of fatty acids (mg fatty acid per g tissue, wet weight) in belly flap, liver, red and white muscle. Apparent digestibility of the fatty acids, measured by adding yttrium oxide as inert marker, was significantly lower in fish fed the PO diet compared to the other three diets.

Animals↗

PubMed1986

Relation between lipid polymorphism and transbilayer movement of lipids in rat liver microsomes.

We have studied the effects of trinitrophenylation on the transbilayer movement of phosphatidylcholine and the macroscopic lipid structure in rat liver microsomal membranes. The transbilayer movement of phosphatidylcholine was investigated using the PC-specific transfer protein. 31P-NMR was employed to monitor the phospholipid organization in intact microsomal vesicles. The results indicate that modification of microsomes with trinitrobenzenesulfonic acid enhances the transbilayer movement of phosphatidylcholine at 4 degrees C. Furthermore, phosphatidylethanolamine headgroup trinitrophenylation in microsomes increases the isotropic component in the 31P-NMR spectra even at 4 degrees C, possibly representing the appearance of intermediate non-bilayer lipid structures. The observed parallel between these data suggests that phosphatidylethanolamine molecules in the microsomal membrane, probably in combination with a protein component, are able to destabilize the bilayer organization, thereby facilitating the transmembrane movement of phospholipids.

Animals↗

PubMed1991

Electromechanical stability of planar lipid membranes from bipolar lipids of the thermoacidophilic archebacterium Sulfolobus acidocaldarius.

Stable planar membranes have been obtained from the bipolar lipid glycerol dialkyl nonitol tetraether (GDNT) extracted from the thermoacidophilic archebacterium Sulfolobus acidocaldarius. The electric capacity Cm, the resistance Rm and tension sigma of these membranes were measured. The dependence of the bipolar lipid membranes mean life time tau 1 on voltage was investigated. It was shown that the irreversible electric breakdown of membranes from GDNT and usual phospholipids is due to the same mechanism, viz., due to formation of a hydrophilic pore with an overcritical radius. Under electric field the GDNT molecules take U-shape, and the polar headgroups of such molecules cover the pore's interior.

Biophysical Phenomena↗

PubMed1977

Age-dependent modulation of 3'-phosphoadenosine-5'-phosphosulfate-galactosylceramide sulfotransferase by lipids extracted from the microsomal membranes and artificial lipid mixtures.

The 3'-phosphoadenosine-5'-phosphosulfate-galactosylceramide-sulfotransferase (cerebroside sulfotransferase) is microsomal enzyme, which shows a definite developmental activity pattern. This report gives evidence that the enzyme activity of partially delipidated microsomes is modulated by the cholesterol:phospholipid ratio of the extracted microsomal lipids in an age-dependent manner. These findings suggest that in vivo the enzyme activity is modulated by the lipid surrounding.

Adenosine Monophosphate↗

PubMed1979

In vitro lipid metabolism in the rat pancreas. I. Basal lipid metabolism.

1. The in vitro basal lipid metabolism of rat pancreatic fragments was compared with that in adipose tissue fragments and liver slices. 2. [1-14C]Acetate added to the media was mostly incorporated into palmitic acid and to a lesser extent into oleic acid. In addition, pancreatic tissue exhibited a marked capacity for elongation of polyunsaturated fatty acids by [1-14C]acetate and resulting desaturation when compared to adipose tissue and liver. 3. Data obtained in the presence of [U-14C]glucose, [1-14C]palmitate and 3H20 indicate that acetyl-CoA derived from glucose and from beta-oxidation of fatty acids contributed to de novo lipogenesis. 4. Oxidation of [1-14C]palmitic acid was 9-13 times higher in the pancreas than in adipose tissue or liver when expressed on a wet weight basis. 5. The fatty acid moiety of pancreatic glycerolipids could be derived from de novo synthesis, fatty acids added to the medium, or from fatty acids formed from the hydrolysis of endogenous lipids. The glycerol moiety could be derived either from glucose, or directly from glycerol through participation of glycerol kinase.

Acetates↗

PubMed1984

Transport of mercury compounds across bimolecular lipid membranes: effect of lipid composition, pH and chloride concentration.

The use of bimolecular lipid membranes (BLM) as model membrane allows the analysis of the transport of mercury compounds across the lipidic barriers of biological membranes. The results of flux measurements show that two mercury compounds--HgCl2 and CH3HgCl--cross the BLM but the overall permeabilities are dependent on the pH of the aqueous media, and are not apparently influenced by the different phospholipid constituents of the bilayers. On the other hand, electrical measurements show that, function of the chemical speciation, the transport of this metal is done essentially in the neutral form.

Biological Transport↗

PubMed1983

Changes in lipid phase behaviour in human myelin during maturation and aging. Involvement of lipid peroxidation.

The biophysical properties of human myelin isolated from white matter of patients aged two months to 74 years were investigated using wide-angle X-ray diffraction. The myelin transition temperature increased from 13 degrees C to 65 degrees C as age increased from two months to 17 years, demonstrating an increase in the myelin lipid stability. Following this maturation period, the myelin transition temperature remained constant at 65 degrees C until age 50. Beyond age 50, the transition temperature of myelin decreased by 13 degrees C indicating that myelin stability decreased with aging. During this aging period, the levels of malondialdehyde and conjugated diene increased, indicating an increasing amount of lipid peroxidation. Although evidence is indirect, the results of this investigation strongly suggest that free radicals could be a primary factor in the acceleration of the aging processes in the human brain.

Adolescent↗

PubMed1985

Effects of casein and soy protein on hepatic and serum lipids and lipoprotein lipid distributions in the rat.

Rats fed a semipurified diet containing casein developed higher levels of circulating triglycerides and cholesterol than animals fed a soy protein-containing diet. The increased serum lipid levels in non-fasted rats were associated largely with the d less than 1.006 g/ml lipoprotein particles (e.g. chylomicrons or very low density-like lipoproteins). In addition, casein-fed rats exhibited higher levels of circulating insulin and depressed hepatic 7 alpha-hydroxylase levels compared to soy-fed rats. Supplementation of the casein diet with arginine, to give an arginine/lysine ratio comparable to that in the soy diet, resulted in a reduction of d less than 1.006 g/ml lipids, a reduction in serum insulin levels and an elevation in hepatic 7 alpha-hydroxylase activity. Supplementation of the soy diet with lysine also resulted in modification of these parameters toward those observed with casein diets, albeit the effects were less dramatic. The results suggest that the hyperlipidemia associated with feeding casein-based diet is associated with decreased rates of clearance of chylomicron-like lipoproteins and their component triglycerides and cholesterol. Furthermore, this is largely prevented by addition of arginine to diets containing casein as the sole protein source.

Animals↗

PubMed1982

Effect of carbon tetrachloride on cardiac lipid peroxidation, serum lipids and enzymes of albino rats.

Carbon tetrachloride (CCl4) at the dose of 0.3 ml/100 g body weight i.p. induced changes after 18 h in the cardiac lipid-peroxidation, serum-free fatty acids (FFA), cholesterol, and enzymes in the rats. The cardiac lipid peroxidation and the activity of serum enzymes GOT and GPT were significantly increased. The levels of serum FFA and cholesterol were significantly decreased.

Alanine Transaminase↗