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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of dietary restriction (half of the control ration) on cholesterol biosynthesis was investigated in rabbits fed either standard or cholesterol-rich diets. Accompanying the amplification of hypercholesterolemia, additional disturbances of cholesterol metabolism were observed when cholesterol feeding was associated with dietary restriction. In the intestine, underfed rabbits showed a more marked inhibition of duodenal cholesterol biosynthesis from [14C]acetate following cholesterol feeding than rabbits on normal caloric ration. In contrast liver cholesterogenesis was equally suppressed in both groups receiving cholesterol-rich diets. Cholesterol biosynthesis from [14C]mevalonate was also inhibited by cholesterol feeding particularly in the duodenum of underfed rabbits. In addition cholesterol feeding induced a marked increase of the labeled esterified: free cholesterol ratio in the liver, demonstrating intensive esterification, this was enhanced by dietary restriction. The additional cholesterol which accumulates in the plasma and in various tissues in underfed rabbits is of dietary origin since the feedback control of cholesterogenesis by exogenous cholesterol was shown to be very effective in these animals.
Exp Mol Pathol 1985 Oct
PMID:Effect of dietary restriction on cholesterol biosynthesis in the liver and the intestine of cholesterol-fed rabbits. 404 45

A multilayered complex forms when a solution of myelin basic protein is added to single-bilayer vesicles formed by sonicating myelin lipids. Vesicles and multilayers have been studied by electron microscopy, biochemical analysis, and X-ray diffraction. Freeze-fracture electron microscopy shows well-separated vesicles before myelin basic protein is added, but afterward there are aggregated, possibly multilayered, vesicles and extensive planar multilayers. The vesicles aggregate and fuse within seconds after the protein is added, and the multilayers form within minutes. No intra-bilayer particles are seen, with or without the protein. Some myelin basic protein, but no lipid, remains in the supernatant after the protein is added and the complex sedimented for X-ray diffraction. A rather variable proportion of the protein is bound. X-ray diffraction patterns show that the vesicles are stable in the absence of myelin basic protein, even under high g-forces. After the protein is added, however, lipid/myelin basic protein multilayers predominate over single-bilayer vesicles. The protein is in every space between lipid bilayers. Thus the vesicles are torn open by strong interaction with myelin basic protein. The inter-bilayer spaces in the multilayers are comparable to the cytoplasmic spaces in central nervous system myelins . The diffraction indicates the same lipid bilayer thickness in vesicles and multilayers, to within 1 A. By comparing electron-density profiles of vesicles and multilayers, most of the myelin basic protein is located in the inter-bilayer space while up to one-third may be inserted between lipid headgroups. When cytochrome c is added in place of myelin basic protein, multilayers also form. In this case the protein is located entirely outside the unchanged bilayer. Comparison of the various profiles emphasizes the close and extensive apposition of myelin basic protein to the lipid bilayer. Numerous bonds may form between myelin basic protein and lipids. Cholesterol may enhance binding by opening gaps between diacyl-lipid headgroups.
J Mol Biol 1984 Apr 05
PMID:Lipid/myelin basic protein multilayers. A model for the cytoplasmic space in central nervous system myelin. 620 18

We have shown that NS-1 mouse myeloma cells, but not NS-1 hybridomas, required human low density lipoprotein (LDL) for survival and growth in serum-free cell culture (Kawamoto et al., 1983). Here we have further defined the lipid requirement of NS-1 cells by demonstrating that LDL could be replaced by cholesterol complexed with carrier bovine serum albumin (BSA). Cholesterol was the active component of this complex since BSA alone did not promote NS-1 survival or growth. Cholesterol was an absolute requirement of these cells, and it could not be replaced by mevalonolactone. In contrast to NS-1 cells a related mouse myeloma cell line, Sp2/0, did not require cholesterol or other lipids for growth in vitro. Finally, we propose that cholesterol-deficient medium may be an effective alternative to HAT medium for selecting NS-1 hybridomas.
Mol Biol Med 1984 Apr
PMID:Cholesterol requirement of NS-1 mouse myeloma cells for growth in serum-free medium. 653 17

The lipid and carbohydrate metabolism of Giardia lamblia was studied using trophozoites isolated from a human and axenically grown in vitro in medium containing fetal bovine serum. The phospholipid, fatty acid and neutral lipid composition of the G. lamblia trophozoites was similar to that of the medium. Phosphatidylethanolamine, phosphatidylcholine and sphingomyelin were the major phospholipids detected; monoacyl-, diacyl-, triacylglycerides, sterols, and sterol esters were the major neutral lipids found. Several unidentified glycolipids were also detected. Glucose and threonine were readily incorporated by the trophozoites, but not into cellular phospholipids or sterols. However, approximately 86% of the glucose incorporated into the trophozoites was found in the nucleic acids, and 38% of the threonine incorporated was detected in the cellular proteins. Small amounts of the glucose and threonine were incorporated into glycolipid-containing fractions. Glycerol and acetate were not appreciably incorporated into trophozoites while glycerol 3-phosphate incorporation was not detected. Cholesterol was readily assimilated by the trophozoites; 98% of the incorporated was found in the sterol fraction. Radiorespirometric data suggest that the major routes of glucose metabolism in G. lamblia are via Embden- Meyerhof-Parnas and pentose phosphate pathways. However, endogenous acetate (as acetyl-CoA) formed during the metabolism of glucose is not used for lipid biosynthesis. These findings suggest that G. lamblia trophozoites are incapable of synthesizing cellular phospholipids or sterols de novo, but rather, utilize lipids already present in the medium.
Mol Biochem Parasitol 1981 Feb
PMID:Lipid and carbohydrate metabolism of Giardia lamblia. 678 99

Studies were performed to determine the ability of alpha-tocopherol and cholesterol to influence the effect of phosphatidylcholine (PC) liposomes on the blastogenic response of bovine peripheral blood lymphocytes (BPBL) to phytohemagglutinin (PHA). BPBL were cultured with liposomes having a molar ratio of cholesterol to PC (C/P) ranging from 0 to 2.0, a molar ratio of alpha-tocopherol to PC (E/P) of 1.0 and a molar ratio of cholesterol + alpha-tocopherol to PC [(C + E)/P] of 2.0 and 4.0 PC liposomes significantly suppressed BPBL blastogenic response to PHA. Cholesterol-rich (C/P greater than or equal to 1.0) liposomes, alpha-tocopherol-rich (E/P = 1.0) liposomes and liposomes rich in cholesterol and alpha-tocopherol [(C + E)/P greater than or equal to 2.0] were able to completely reverse PC liposome suppression of BPBL. There was no molar ratio [C/P, E/P or (C + E)/P] that was able to enhance the blastogenic response of BPBL above the response obtained with PHA alone. The results suggest that the augmentation of PC liposomes rich in cholesterol, alpha-tocopherol and cholesterol with alpha-tocopherol (C/P and E/P greater than or equal to 1.0) was equally capable of restoring normal responses in BPBL but did not enhance or suppress the response to PHA.
Mol Immunol 1982 Jan
PMID:Effects of enrichment of phosphatidylcholine liposomes with cholesterol or alpha-tocopherol on the response of lymphocytes to phytohemagglutinin. 707 58

Live adult Schistosoma mansoni, maintained in vitro were able to absorb and utilize radiolabelled arachidonic acid, linolenic acid, 3-sn-phosphatidylcholine, tripalmitylglycerol and cholesterol in the culture medium. Differential centrifugation demonstrated that all these lipids were incorporated into the parasite's various membrane structures. Analysis by thin-layer chromatography of the labelled compounds which resulted from incubation with the labelled lipids revealed that arachidonic acid, linolenic acid and fatty acids of tripalmitylglycerol and 3-sn-phosphatidylcholine were present largely as triacylglycerol with smaller amounts of labelled diacylglycerol, phospholipids and fatty acids. The labelled polar head group of 3-sn-phosphatidylcholine was cleaved from the molecule during incorporation, which suggested that hydrolysis of complex lipids is an integral part of the absorption mechanism. Cholesterol was not apparently altered during incorporation or further metabolized. It was also observed that arachidonic acid was incorporated more readily than the other lipids, however, no prostaglandin biosynthesis was detected.
Mol Biochem Parasitol 1980 Mar
PMID:The incorporation and utilization of radiolabelled lipids by adult Schistosoma mansoni in vitro. 744 9

Cholesterol-derived oxysterols such as cholestanol, cholestanone and coprostanone were able to potentiate epinephrine-induced lipolysis in intact rat adipocytes but not cholesterol. The relative potency of the oxysterols followed the sequence: cholestanone > or = coprostanone > cholestanol. Cholestanone was selected to study its mode of action on epinephrine-induced lipolysis. A sustained increase in the level of cAMP was observed in adipocytes incubated with both cholestanone and epinephrine compared to a transient peaking of cAMP in adipocytes incubated with epinephrine alone. Binding assays using [125I]cyanopindolol (beta-adrenergic receptor antagonist) showed that cholestanone could increase the binding affinity of [125I]-cyanopindolol to beta-adrenergic receptors on rat adipocyte ghost membranes without affecting the total number of binding sites. The results suggest that cholestanone exerts its potentiation effect by facilitating the binding of beta-adrenergic agonist to its receptor.
Biochem Mol Biol Int 1995 May
PMID:Potentiation of beta-adrenoceptor agonist mediated-lipolysis by cholesterol-derived oxysterols. 749 73

A membrane fraction enriched with plasma membranes was isolated from rat ileal brush-border cells before and after five-day starvation of the animals. Cholesterol/phospholipid ratio of the standard cell membranes decreased highly significantly (0.42 to 0.18), as did the microviscosity of the membranes determined by polarization of fluorescence (0.187 to 0.142). Concomitantly, the specific activity of Na,K-ATPase in the basolateral membranes significantly increased (59 to 83 mumol ATP hydrolyzed per mg protein per min).
Biochem Mol Biol Int 1995 Apr
PMID:Modifications of functional and physico-chemical properties of rat ileal plasma membranes. 762 34

Cholesterol synthesis both ex vivo and in vivo in liver and ileum of hamsters was significantly inhibited by fluvastatin. This ex vivo inhibition was considerably lower in fluvastatin-treated hamsters than in fluvastatin-treated rats. In hamsters and rats, fluvastatin was more potent than pravastatin on inhibitory activities of sterol synthesis in liver, but not in the hamster ex vivo. This may indicate that, in part, the hydrophobicity of the fluvastatin molecule confers the selectivity and metabolism in the liver of hamsters and rats to originate from the species differences.
Res Commun Mol Pathol Pharmacol 1994 Dec
PMID:Species differences in the inhibiting effect of fluvastatin, a new inhibitor of HMG-CoA reductase, on cholesterol biosynthesis. 771 8

The effect of retinol deficiency and curcumin and turmeric feeding on brain microsomal Na(+)-K(+)ATPase activity was investigated. The brain Na(+)-K(+)ATPase activity registered an increase of 148.5% as compared to the control group. Upon treating retinol deficient rats with curcumin or turmeric, the abnormally elevated activity showed a decrease of 36.9 and 47.1%, respectively, when compared to the retinol deficient group. An increase in Vmax by 67% and Km by 66% for ATP was observed in the retinol deficient group. Curcumin or turmeric fed retinol-deficient groups reduced the Vmax by 25 and 33%, while Km was reduced by 25 and 31%, respectively, compared to the retinol deficient group. Arrhenius plot of Na(+)-K(+) ATPase showed a typical bi-phasic pattern in all the groups. Cholesterol:Phospholipid ratio showed a decrease in the retinol-deficient group by 67.8%, which showed a marked increase in curcumin or turmeric treated groups. Detergents could increase the Na(+)-K(+) ATPase activity more in the control group than in the retinol deficient groups. Curcumin or turmeric improved the detergent action on the enzyme. Subsequent freezing and thawing over a period of 30 min decreased the enzyme activity by 22.8% in the retinol deficient group compared to 15.9% decrease in the control group. Curcumin or turmeric treated groups showed a decrease in the enzyme activity by 22.0 and 19.2%, respectively, when compared to the zero time in each group. In the presence of concanavalin-A (Con-A) there was only 52.4% stimulation in the enzyme activity in retinol deficient groups, compared to 108.0% in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1994 Aug 31
PMID:Effect of retinol deficiency and curcumin or turmeric feeding on brain Na(+)-K+ adenosine triphosphatase activity. 784 84


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