Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the screening of samples obtained from 5 individuals with type III hyperlipidemia, we identified a variant of apolipoprotein (apo) E which exhibited a discrepancy in apo E phenotype showing the E3/E1 isoform on isoelectric focusing (IEF) analysis and E3/E3 on gene analysis. Sequence analysis of the DNA of the proband that was amplified by PCR and subcloned, revealed a single substitution of one lysine (AAG) for one glutamic acid (GAG) at position 146, thereby adding two negatively charged units to apo E3. This defect had been described only for apo E1 to date (Mann et al. (1989) Clin. Res. 37, 520A (abstract)). In this case, PCR-mediated site-directed mutagenesis was used to identify the structural alterations forming the abnormal E1 genotype in the proband's family. Purified apo E1 Lys-146----Glu showed less than 10% of binding activity to apo B, E receptor on human skin fibroblasts compared with apo E3. This substitution demonstrates that Lys-146 is essential for the binding of apo E to the receptor.
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PMID:Apolipoprotein E1 Lys-146----Glu with type III hyperlipoproteinemia. 135 43

The effects of bound fatty acids and nonenzymatic glycosylation (NEG) on tryptophan binding to human serum albumin (HSA) were examined utilizing a rate of dialysis technique. HSA with 0, 1, 2, 3, or 5 mol of palmitate bound per mol of HSA was glycosylated in vitro to a level exceeding that seen in diabetes. NEG was not inhibited by fatty acids, suggesting that Lys-525, the primary site for NEG, is not an essential component of the principal sites for long-chain fatty acid binding to HSA. Scatchard analysis of binding data showed an expected fatty acid dependent decrease in the number of available tryptophan binding sites, but showed that fatty acids did not affect tryptophan affinity. The binding data failed to show an effect of NEG on tryptophan binding. The lack of inhibition of tryptophan binding by NEG suggests that drug-binding Site II, the indole/benzodiazepine site, is resistant to both NEG and to any conformational changes in HSA which may occur with NEG. These data suggest that elevated plasma free tryptophan and the resulting altered serotonin metabolism seen in diabetes are independent of increased NEG and likely result from diabetic hyperlipidemia.
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PMID:Effects of nonenzymatic glycosylation and fatty acids on tryptophan binding to human serum albumin. 157 75

The 3' end of the apo B gene is highly polymorphic. Two point mutations in the coding sequence of the gene create EcoRI (E+, E-) and XbaI (X+, X-) RFLPs. The two loci are in random association and the frequency of the four haplotypes, E+X+, E+X-, E-X+ and E-X- in the normolipidaemic population are 0.68, 0.30, 0.02 and 0.00, respectively. Although the polymorphic nucleotide underlying the EcoRI RFLP creates an amino acid substitution in the apo B protein (Glu----Lys) in a region close to a putative LDL-receptor recognition site(s), we find no statistically significant difference in the frequency of the apo BGlu and apo BLys alleles in hyperlipidaemic patients (familial hypercholesterolaemia, type IIA with no tendon xanthomas, IIB and probably IV) and the normolipidaemic population. In contrast, we confirm previous findings, that the X+ allele is in linkage disequilibrium with a genetic locus that predisposes to the development of higher fasting plasma triglyceride levels than the X- allele. We have characterized a highly polymorphic region immediately 3' to the apo B gene. At least 5 alleles of this locus exist in the population and our family studies show it should be an extremely informative locus to use in studies where polymorphic or mutant apo B alleles are suspected to underly certain forms of familial hyperlipidaemia. DNA sequence analysis of this highly polymorphic locus shows that the variation is entirely attributable to the number of times the simple repeating sequence 5'-TTTATAATTAAAATATTTATAATTAAATAT-3' is present.
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PMID:Characterization of genetic markers in the 3' end of the apo B gene and their use in family and population studies. 289 57

The effect of diets containing soybean proteins substituting a significant portion of meat proteins was studied in patients with hyperlipidemia, type IIa, and in experiments on rats. It was found that soybean proteins included into the diet induced blood plasma amino acid imbalance, changed the excretion of some amino acids with urine, and significantly diminished the blood plasma cholesterol level. In the experiments on rats a reduced rate was noted in the low-density lipoprotein apoprotein formation and high-density lipoprotein apoprotein regeneration in the blood plasma. It is suggested that the hypocholesterolemic effect of soybean proteins is caused by decreased apoprotein E synthesis and metabolism due to low levels of blood plasma lysine and arginine.
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PMID:[Clinico-experimental approaches to studying the hypocholesteremic action of soy proteins]. 370 42

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.
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PMID:Effects of casein and soy protein on hepatic and serum lipids and lipoprotein lipid distributions in the rat. 393 24

We have isolated an isoform of the protein activator of lipoprotein lipase, apolipoprotein C-II, from the very low density lipoproteins of four patients of African ancestry with hypertriglyceridemia and eruptive or pedunculated xanthomata. This protein, which we designate apolipoprotein C-II2, differs from the previously recognized species, which we denote apolipoprotein C-II1, by substitution of glutamine for lysine at residue 55, a mutation which would require only a single-base substitution in the structural gene for apolipoprotein C-II1. Each of the patients in whom apolipoprotein C-II2 was found had approximately equal amounts of apolipoprotein C-II1 and apolipoprotein C-II2 among the apoproteins of the very low density lipoproteins, suggesting that the structural genes for these proteins are allelic. Two additional apparent heterozygotes were found among the first-degree relatives of each of two of the patients in patterns compatible with monogenic autosomal transmission. Approximately equal amounts of apolipoproteins C-II2 and C-II1 were also found by isoelectric focusing in 6 of a casual series of 50 normolipidemic blacks, but none or only trace amounts of apolipoprotein C-II2 were found in 500 samples from Caucasian subjects with hyperlipidemia. These findings suggest that this polymorphism is distributed primarily among blacks, possibly reflecting some positive Darwinian selection pressure. Whether this polymorphism has a modifying effect upon the development of hyperlipemia remains to be determined.
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PMID:A variant primary structure of apolipoprotein C-II in individuals of African descent. 394 71

To study the mechanism of the increase in serum lipoproteins which occurs in rats fed alcohol chronically, and especially to assess the role of the intestine, the effects of acute and chronic ethanol administration on lymph and plasma lipids were compared in rats with and without intestinal lymph fistulae. In rats not previously given alcohol, the administration of one dose of a diet containing ethanol (3 g/kg) produced a significant increase in lymph flow, lipid output, and incorporation of dietary fat into lymph lipids when compared with the effects of a control diet containing isocaloric carbohydrate. However, no hyperlipemia developed after ethanol. By contrast, previous feeding of ethanol for several weeks modified the acute effects of ethanol on both lymph and serum lipids. Compared with control animals pair-fed with isocaloric carbohydrate-containing diets, rats which had been fed a diet with 36% of total calories as ethanol for 3-4 wk developed postprandial hyperlipemia when given a single dose of the ethanol-containing or even the ethanol-free diet. This was associated with an increased incorporation of labeled dietary fat and of intravenously injected [(3)H]lysine into plasma lipoproteins of d < 1.006. However, postprandial lymph flow and lipid output were not higher in rats fed alcohol chronically than in their pair-fed controls. Moreover, when rats with lymph fistulae were given intravenous (i.v.) infusions of lymph lipids (to substitute for the diverted intestinal lymph), the ethanol-fed animals still developed hyperlipemia. Incorporation of i.v. lysine into d < 1.006 plasma lipoproteins also remained significantly increased. Thus, under these conditions, alcoholic hyperlipemia does not result from changes in intestinal lymph lipids. Two main factors appear to be involved; the acute effects of ethanol on hepatic lipid metabolism and the development of an increased capacity for lipoprotein synthesis during chronic ethanol feeding. The latter most likely occurs in the liver and it is postulated that it is linked to the associated changes in the hepatic endoplasmic reticulum.
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PMID:Pathogenesis of postprandial hyperlipemia in rats fed ethanol-containing diets. 468 74

In rats, chronic ethanol feeding was found to enhance the postprandial hyperlipemia and to increase the incorporation of dietary palmitic acid-(3)H and intravenously injected L-lysine-(14)C into serum lipoproteins. The main increases of total amount, labeling, and specific activity of lipid and protein occurred in the d < 1.019 lipoprotein fraction. Fat absorption and the clearance of injected chylomicrons were not affected by ethanol feeding. Blocking of lipoprotein and chylomicron removal with Triton did not prevent the action of ethanol on serum lipids, indicating that the ethanol effect is not likely due to defective removal of lipids from the circulation. Ethanol enhanced the incorporation of chylomicron fatty acids into newly synthetized very low density lipoproteins, as shown by an increased reappearance of the fatty acid label into the lipids of this fraction after injection of palmitate-(14)C/glycerol-(3)H doubly labeled chylomicrons. These results indicate that alcoholic hyperlipemia is due, at least in part, to an increase in newly synthetized lipoproteins. The hyperlipemia produced by ethanol was accompanied by hepatic steatosis. The simultaneous production of fatty liver and hyperlipemia makes it unlikely that defective lipoprotein synthesis or secretion is a primary mechanism for the pathogenesis of the alcoholic fatty liver.
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PMID:Efcts of chronic ethanol feeding on serum lipoprotein metabolism in the rat. 544 77

Feeding diets with 4% L-lysine to the chick produces an elevation of plasma lipids which does not occur when feeding an excess of any other amino acid. Experiments were conducted to determine whether lysine-induced hyperlipidemia is secondary to the antagonistic effect of lysine on arginine or to the anorexia which accompanies lysine feeding, and in addition, whether the lysine-induced hypercholesterolemia is affected by chick age. In all experiments gain and food intake were reduced by feeding chicks 4% lysine. Plasma cholesterol and triglyceride were elevated, but high-density-lipoprotein cholesterol, as a percentage of total, was reduced. Addition of dietary arginine up to 4% failed to reverse the depression in performance and elevation of plasma lipids. Pair-feeding the control diet to the amount consumed by lysine-fed chicks did not elevate plasma lipids above control levels. Thus, lysine-induced hyperlipidemia is not mediated by the antagonistic effect of lysine on arginine nor by the effect of lysine on food intake. The high-lysine diet prevented the normal decline in plasma cholesterol expected with advancing age of chicks. Preliminary results suggested that excess lysine stimulated cholesterol biosynthesis.
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PMID:Effect of excess dietary lysine on plasma lipids of the chick. 641 75

The lipid-lowering effect of carnitine and its precursors, namely lysine plus methionine, was examined in male Sprague-Dawley rats fed ethanol as 36% of the total calories. Ethanol caused typical hepatic steatosis characterized by significant accumulation of total lipids, triglycerides, cholesterols, phospholipids, and free fatty acids. Supplementation of the ethanol diet with 1% DL-carnitine, 0.5% L-lysine, and 0.2% L-methionine significantly lowered ethanol-induced increases of various lipid fractions, with the exception of free fatty acids. The lipid-lowering effect of carnitine was superior to that of its precursors and their effect together was no greater than that of carnitine alone. The triglyceride contents of liver and plasma were related inversely to the levels of carnitine and acyl carnitines. It is concluded that dietary carnitine more effectively than its precursors prevented alcohol-induced hyperlipemia and accumulation of fat in livers. Thus, a deficiency of functional carnitine may indeed exist in chronic alcoholic cases.
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PMID:Ameliorating effects of carnitine and its precursors on alcohol-induced fatty liver. 642 29


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