| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Obesity, overweight, hypertension, and high blood cholesterol: the importance of age Flegal, K. M. (2000), Obes Res 8(9): 676-7. |
| Observation of cholesterol nucleation in a magnetic field Sandarac, N. M., M. Ashok, et al. (2002), Acta Crystallogr D Biol Crystallogr 58(Pt 10 Pt 1): 1711-4. Abstract: The in vitro studies on the nucleation, growth and other fundamental aspects of cholesterol crystallization have received considerable attention, as it plays a vital role in the formation of atheroclerotic plaques and gallbladder stones. The cholesterol was crystallized in methanol, ethanol, acetone and isopropanol at the physiological temperature of 37 degrees C in the presence and absence of a low static magnetic field at 0.1 T. The presence of magnetic field was found to have a significant effect on the metastable zone width and induction period of cholesterol. |
| Observed relationship between ratios HDL-cholesterol/total cholesterol and apolipoprotein A1/apolipoprotein B Kuyl, J. M. and D. Mendelsohn (1992), Clin Biochem 25(5): 313-6. Abstract: Epidemiological evidence suggests that the ratio HDL-cholesterol (HDL-C)/total cholesterol (TC) or apolipoprotein A1 (apo A1)/apolipoprotein B (apo B) are good indicators of coronary heart disease risk. In investigating the distribution of these ratios in the typical population served by our routine laboratory, we analysed the lipid results of 541 serum samples submitted over a 2-month period for TC, HDL-C, apo A1, and apo B. Good correlation was observed between HDL-C and apo A1 (r = 0.664), and between TC and apo B (r = 0.674). Surprisingly, the correlation between the ratios HDL-C/TC (range: 0.05-0.40) and apo A1/apo B (range: 0.27-3.71) was even higher (r = 0.822). Similar significant correlations were observed in 31 heterozygous and 20 homozygous familial hypercholesterolemic subjects, viz. the correlations between HDL-C/TC (ranges: 0.04-0.24 and 0.02-0.12, respectively) and apo A1/apo B (ranges: 0.47-1.84 and 0.15-1.12, respectively) were r = 0.951 and r = 0.972, respectively. |
| Obstructive jaundice caused by a cholesterol polyp of the gallbladder: report of a case Takii, Y., Y. Shirai, et al. (1994), Surg Today 24(12): 1104-6. Abstract: We present herein the case of a 34-year-old man in whom obstructive jaundice was found to be caused by an impacted detached cholesterol polyp. A cholecystectomy with exploration of the common bile duct was performed after ultrasonography showed cholesterol polyps and stones in the gallbladder. Intraoperative cholangioscopy demonstrated an impacted cholesterol polyp at the distal end of the common bile duct which appeared to be detached from the gallbladder. To our knowledge, this is the first report of an impacted detached cholesterol polyp causing obstructive jaundice. |
| Occupational exposure to lead and blood cholesterol in glucose-6-phosphate dehydrogenase deficient and normal subjects Cocco, P. L., E. Cocco, et al. (1991), Res Commun Chem Pathol Pharmacol 72(1): 81-95. Abstract: The effect of chronic lead poisoning on blood cholesterol levels of 148 patients, admitted to the Institute of Occupational Medicine of the University of Cagliari (Italy), was studied in connection with the genetic pattern of Glucose-6-Phosphate Dehydrogenase (G6PD) activity. The erythrocyte G6PD activity of twenty-six patients was genetically deficient. Multiple regressions were elaborated including the following in the model as independent variables: age, Quetelet index and blood lead or urinary lead in the 24 hours following 15 mg/Kg of i.v. calcium ethylen-diamine-tetracetate (EDTA) (PbUEDTA), expressed as a ratio with body weight (PbUEDTA/Kg). Dependent variables were alternatively, total cholesterol, cholesterol esters, LDL and HDL cholesterol. The analysis showed that G6PD deficient subjects have generally lower intercepts, but only for HDL the difference approached the statistical significance. Lead poisoning affected blood cholesterol of G6PD deficient subjects differently from normal ones: while total cholesterol and LDL tended to decrease in both, positive slopes were observed for cholesterol esters in G6PD deficient and for HDL in G6PD normal subjects. |
| Occurrence of cholesterol 7 alpha- and 7 beta-hydroperoxides in rat skin as aging markers Ozawa, N., S. Yamazaki, et al. (1991), Biochem Biophys Res Commun 178(1): 242-7. Abstract: Evidence for presence of cholesterol 7 alpha- and 7 beta-hydroperoxides in rat skin was presented for the first time. The 7-hydroperoxides in rat skin were reduced with sodium borohydride and trimethylsilylated for identification with the authentic compounds by gas chromatography/mass spectrometry. A content of cholesterol 7-hydroperoxides in rat skin, determined by high performance liquid chromatography with a chemiluminescence detector, highly correlated with the age of rats (r = 0.874; between 1 and 45 weeks old), indicating that cholesterol 7 alpha- and 7 beta-hydroperoxides were good markers for aging. |
| Oestrogen receptor dinucleotide (TA) polymorphism affects total and LDL cholesterol but does not predict premature myocardial infarction in Caucasian men Letonja, M., K. Steblovnik, et al. (2005), Acta Cardiol 60(3): 307-9. Abstract: OBJECTIVE: The aim of this association study was to test the hypothesis whether the oestrogen receptor gene dinucleotide (TA) polymorphism is a risk factor for premature myocardial infarction in Caucasian men. Moreover, we investigated an association between oestrogen receptor gene dinucleotide (TA) polymorphism and serum lipid levels. METHODS AND RESULTS: One hundred and thirty men with premature myocardial infarction were compared with healthy men. Cases and controls did not demonstrate a statistically significant difference in distribution of the oestrogen receptor dinucleotide (TA) gene polymorphism alleles. Neither did we demonstrate the length of the dinucleotide (TA) repeats of the oestrogen gene to be associated with premature myocardial infarction in Caucasian men. Subjects with larger alleles (both alleles of > or =19 repeats) differed from subjects with other genotypes in serum total and LDL cholesterol, but not in HDL cholesterol and triglycerides. CONCLUSIONS: Despite an association between the oestrogen receptor gene dinucleotide (TA) polymorphism in the regulatory region of the alpha oestrogen receptor gene and serum total and LDL cholesterol, our study suggests that the oestrogen polymorphism is not associated with premature myocardial infarction in Caucasian men. |
| Of rodents, humankind, and cholesterol Lindenmayer, J. M. (1996), Med Health R I 79(4): 148-50. |
| Oleate and other long chain fatty acids stimulate low density lipoprotein receptor activity by enhancing acyl coenzyme A:cholesterol acyltransferase activity and altering intracellular regulatory cholesterol pools in cultured cells Rumsey, S. C., N. F. Galeano, et al. (1995), J Biol Chem 270(17): 10008-16. Abstract: Modification of dietary fatty acid composition results in changes in plasma cholesterol levels in man. We examined the effect of in vitro fatty acid supplementation on low density lipoprotein (LDL) receptor activity in cultured cells and questioned whether changes were related to fatty acid-induced alterations in acyl-CoA: cholesterol acyltransferase (ACAT) activity. Preincubation of cultured cells (i.e. human skin fibroblasts, J774 macrophages, and HepG2 cells) with oleic acid (oleic acid:bovine serum albumin molar ratio 2:1) at 37 degrees C for longer than 2 h resulted in a 1.2- to 1.5-fold increase in LDL cell binding at 4 degrees C and LDL cell degradation at 37 degrees C. Scatchard analysis showed that oleic acid increased LDL receptor number but not LDL affinity (Kd). Fatty acid supplementation of J774 macrophages increased both LDL receptor activity and cholesteryl ester accumulation. The ACAT inhibitor, 58-035, eliminated both effects, and increased ACAT activity preceded stimulation of LDL receptor activity by 1-2 h. Supplementation of macrophages with triolein emulsion particles also increased LDL cell binding and degradation, and addition of cholesterol to the emulsions abolished this effect. Among fatty acids tested, oleate (18:1), arachidonate (20:4), and eicosapentanoate (20:5) demonstrated the greatest effects. We hypothesize that certain fatty acids delivered to cells either in free form, or as triglyceride, first increase cellular ACAT activity, which then causes a decrease in an intracellular free cholesterol pool, signaling a need for increased LDL receptor activity. This mechanism may play a role in the effect of certain dietary fatty acids on LDL metabolism in vivo. |
| Oleate, linoleate and cholesterol differently modify aspartyl- and glutamyl-aminopeptidase activities in primary cultures of rat astrocytes Ramirez-Exposito, M. J., J. M. Martinez-Martos, et al. (2001), Comp Biochem Physiol C Toxicol Pharmacol 128(1): 113-8. Abstract: The intake of mono- and polyunsaturated fatty acids has been associated with a minor risk of cardiovascular diseases including hypertension. Changes in levels of fatty acids may also modify the cell activity and may be related with alterations in different regulatory processes. Aminopeptidases are zinc-metalloenzymes which metabolise circulating peptide hormones in several tissues. Glutamyl-aminopeptidase (GluAP) and to a lesser extent, aspartyl-aminopeptidase (AspAP), are related with angiotensin metabolism in the renin-angiotensin system. The present work was designed to study the effect of a range of concentrations (1-100 microM) of oleic and linoleic acids and cholesterol present in the culture medium on the activity of GluAP and AspAP in the culture of rat cerebral cortical astrocytes taken from 21-day-old fetuses. The results showed that oleic acid inhibits, while linoleic acid stimulates the activity of AspAP. Both fatty acids inhibit the activity of GluAP. Cholesterol stimulates the activity of both enzymes. On the basis of these results, a functional link may exit between the effects of fatty acids on hypertension and the modulation of aminopeptidase activity by these compounds in rat astrocytes, as an example of target cell type in the central nervous system. |
| Oleic acid inhibits cholesteryl esterase and cholesterol utilization for testosterone synthesis in mouse Leydig cells Meikle, A. W., J. C. Cardoso de Sousa, et al. (1996), Metabolism 45(3): 293-9. Abstract: We have observed that nonesterified fatty acids (NEFA) inhibit testosterone synthesis in response to luteinizing hormone (LH) in mouse Leydig cells, possibly by affecting cholesterol utilization or endogenous concentrations. We have now studied the influence of oleic acid (OA) on the cellular content of cholesterol, hydrolysis of cholesterol esters, and steroidogenesis in isolated mouse Leydig cells. OA (700 micromol/L added with fatty acid-free FAF albumin, 3 g/dL) significantly (P<.025) reduced testosterone production in response to LH (10 ng/mL), total cholesterol concentrations of Leydig cells and the culture medium, and cholesteryl esterase activity in the cytosol and mitochondria. We also studied the effects of OA on steroidogenesis and cellular cholesterol concentrations after treatments to increase cellular cholesterol. OA at lower concentrations (5 micromol/L with albumin, 0.1 g/dL) or low-density lipoprotein (LDL 4 micrograms protein/mL) increased cellular cholesterol (P<.01) without affecting basal steroidogenesis. These treatments failed to reverse the inhibitory (P<.05) effect of OA on testosterone synthesis following LH stimulation, but did significantly (P<.01) increase cellular cholesterol. In summary, OA appears to inhibit testosterone synthesis by inhibiting cholesteryl esterase activity. |
| Oleic acid serum phospholipid content is linked with the serum total- and LDL-cholesterol in elderly subjects Haban, P., E. Zidekova, et al. (2000), Med Sci Monit 6(6): 1093-7. Abstract: INTRODUCTION: Increased dietary intake of the olive oil has been found to lower several cardiovascular risk factors. Aim of our study was to check if there is any link between the oleic acid (OL-18:1n9) serum phospholipid (SPL) content and some of these factors in subjects living relatively far from the Mediterranean region and in habitual conditions, i.e. without any dietary intervention. MATERIAL AND METHODS: The investigated group included 62 out-patients older than 51 yr. Serum lipids were measured using standard hospital laboratory methods, the LDL-cholesterol was calculated using Friedewald's formula. Gas chromatography was used for estimation of fatty acids (FA) in SPL, their values were calculated as relative percentages of all FA. RESULTS: There was a statistically significant inverse correlation between the OL SPL content and the serum total cholesterol (TCHOL) in all 62 patients (r = -0.294; p = 0.020). Analogous correlation was marginally significant for the LDL (r = -0.245; p = 0.055). After a division into 2 groups based on the median of the OL, the group with OL higher than median had significantly lower both TCHOL and LDL (p = 0.014; p = 0.033, respectively). OL correlated positively with the alpha-linolenic acid (18:3n3; r = 0.281; p = 0.027) but inversely with the stearic acid (18:0; r = -0.303; p = 0.017). CONCLUSION: The subjects with less OL in their SPL had higher TCHOL and LDL serum levels and also their fatty acid SPL spectrum showed some other features which may be characterized as undesirable. This is an independent argument emphasizing the need for enhancing OL dietary intake. |
| Oleic acid-rich fats increase the capacity of postprandial serum to promote cholesterol efflux from Fu5AH cells Sakr, S. W., C. Senault, et al. (1996), Biochim Biophys Acta 1300(1): 49-55. Abstract: Cell cholesterol efflux to serum is stimulated after an oral fat load. The impact of meal fatty acid composition was explored by measure of serum promoted cholesterol efflux from Fu5AH cells after ingestion of 4 different fats: sunflower (Sf), oleic-sunflower (Ol), a mixed oil (Mx), and beef tallow (Bt). High density lipoprotein (HDL)2 and HDL3 were isolated and analyzed. Cholesterol efflux increased regularly after Ol (P<0.05 at 4 h and P<0.02 at 8 h), and 8 h after Mx (P<0.02) or Bt (P<0.05), but not after Sf. Percent HDL3 phospholipids increased after Ol (P<0.05 at 6 h and P<0.01 at 8 H) and 8 h after Mx (P<0.01). After Ol, variations in efflux and percent phospholipids in HDL3 (but not HDL2) were positively correlated (r=0.929; P=0.007 at 6 h). Using HDL3, efflux increased 6 h after Ol (P<0.05) but not after Sf, and efflux was correlated with HDL3 phospholipid concentration in medium (r=0.913; P=0.011). Thus postprandial increase in cholesterol efflux in influenced by ingested fats in relation to increased phospholipid availability on HDL3. The protective effect of monounsaturated fatty acids against atherogenesis might be partly mediated by an enhanced ability of postprandial serum to accept cell cholesterol. |
| Oligomerization of Vibrio cholerae cytolysin yields a pentameric pore and has a dual specificity for cholesterol and sphingolipids in the target membrane Zitzer, A., O. Zitzer, et al. (1999), J Biol Chem 274(3): 1375-80. Abstract: Vibrio cholerae cytolysin permeabilizes animal cell membranes. Upon binding to the target lipid bilayer, the protein assembles into homo-oligomeric pores of an as yet unknown stoichiometry. Pore formation has been observed with model liposomes consisting of phosphatidylcholine and cholesterol, but the latter were much less susceptible to the cytolysin than were erythrocytes or intestinal epithelial cells. We here show that liposome permeabilization is strongly promoted if cholesterol is combined with sphingolipids, whereby the most pronounced effects are observed with monohexosylceramides and free ceramide. These two lipid species are prevalent in mammalian intestinal brush border membranes. We therefore propose that, on its natural target membranes, the cytolysin has a dual specificity for both cholesterol and ceramides. To assess the stoichiometry of the pore, we generated hybrid oligomers of two naturally occurring variants of the toxin that differ in molecular weight. On SDS-polyacrylamide gel electrophoresis, the mixed oligomers formed a pattern of six distinct bands. Ordered by decreasing electrophoretic mobility, the six oligomer species must comprise 0 to 5 subunits of the larger form; the pore thus is a pentamer. Due to both lipid specificity and pore stoichiometry, V. cholerae cytolysin represents a novel prototype in the class of bacterial pore-forming toxins. |
| Oligomerization of VIP21-caveolin in vitro is stabilized by long chain fatty acylation or cholesterol Monier, S., D. J. Dietzen, et al. (1996), FEBS Lett 388(2-3): 143-9. Abstract: VIP21-caveolin is one of the components which form the cytoplasmic surface of caveolae. In vivo, this integral membrane protein is found in homo-oligomers with molecular masses of approximately 200, 400 and 600 kDa. These oligomers are also formed by the addition of cytosol to the in vitro synthesized and membrane inserted VIP21-caveolin. Here we show that long chain fatty acyl coenzyme A esters can completely substitute for cytosol in inducing 200 kDa and 400 kDa complexes, whereas 25-hydroxy-cholesterol can produce the 200 kDa oligomer. In order to understand whether acylation of VIP21-caveolin itself is a prerequisite for oligomerization, we studied a mutant protein lacking all three cysteines. When analyzed by velocity sucrose gradient centrifugation in the presence of the non-ionic detergent octylglucoside, both palmitoylated and non-palmitoylated VIP21-caveolin formed oligomers that were indistinguishable. However, only the oligomers of the non-palmitoylated protein are disrupted when analyzed by SDS-PAGE without boiling. These data suggest that the protein domains of VIP21-caveolin are the primary determinants of oligomerization, but that palmitoylation of cysteine residues can increase the stability of the oligomers. |
| Olive oil instead of butter increases net cholesterol excretion from the small bowel Bosaeus, I., L. Belfrage, et al. (1992), Eur J Clin Nutr 46(2): 111-5. Abstract: Butter was replaced by olive oil in a controlled 100 g fat diet in order to study the effect of saturated fats (SAFA) versus monounsaturated fats (MUFA) on small-bowel sterol excretion in eleven healthy ileostomates. Bile acids and neutral sterols were measured by gas-liquid chromatography. Net cholesterol excretion (excretion minus intake) was 84 +/- 25 mg/24 h (mean +/- SE) on the SAFA diet and increased to 218 +/- 32 mg/24 h on the MUFA diet (P less than 0.01). The bile acid excretion tended to be somewhat lower on the MUFA diet, but this was significant only for chenodeoxycholic acid. Net sterol excretion (the sum of excretion of net cholesterol and bile acids) was significantly lower on the SAFA diet than on the MUFA diet (443 +/- 60 and 529 +/- 58 mg/24 h, respectively). The immediately increased excretion of cholesterol from the small bowel could thus explain the serum cholesterol-lowering effect of a change from a SAFA-rich to a MUFA-rich diet, though the mechanism for this change is still unclear. |
| Olive oils improve lipid metabolism and increase antioxidant potential in rats fed diets containing cholesterol Gorinstein, S., H. Leontowicz, et al. (2002), J Agric Food Chem 50(21): 6102-8. Abstract: The effect of olive oils on lipid metabolism and antioxidant activity was investigated on 60 male Wistar rats adapted to cholesterol-free or 1% cholesterol diets. The rats were divided into six diet groups of 10. The control group (control) consumed the basal diet (BD) only, which contained wheat starch, casein, cellulose, and mineral and vitamin mixtures. To the BD were added 10 g/100 g virgin (virg group) or Lampante (Lamp group) oils, 1 g/100 g cholesterol (chol group), or both (chol/virg group) and (chol/Lamp group). The experiment lasted 4 weeks. Plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides (TG), total phospholipids (TPH), HDL-phospholipids (HDL-PH), total radical-trapping antioxidative potential (TRAP), malondialdehyde lipid peroxidation (MDA), and liver TC were measured. Groups did not differ before the experiment. In the chol/virg and chol/Lamp vs chol group, the oil-supplemented diets significantly (P < 0.05) lessened the increase in plasma lipids due to dietary cholesterol as follows: TC (25.1 and 23.6%), LDL-C (39.3 and 34.7%), TG (19.3 and 17.0%), and TC in liver (36.0 and 35.1%) for the chol/virg and chol/Lamp group, respectively. The chol/virg and chol/Lamp diets significantly decreased the levels of TPH (24.7 and 21.2%; p < 0.05 in both cases) and HDL-PH (22.9 and 18.0%; p < 0.05 in both cases) for the chol/virg and chol/Lamp group, respectively. Virgin and Lampante oils in rats fed basal diet without cholesterol did not affect the lipid variables measured. Virgin, and to a lesser degree Lampante, oils have increased the plasma antioxidant activity in rats fed BD without cholesterol (an increase in TRAP, 20.6 and 18.5%; and a decrease in MDA, 23.2 and 11.3%, respectively). In the rats of chol/virg and chol/Lamp vs Chol diet groups the added oils significantly hindered the decrease in the plasma antioxidant activity (TRAP, 21.2 and 16.7%; and MDA, 27.0 and 22.3%, respectively). These results demonstrate that virgin, and to less degree Lampante, oils possess hypolipidemic and antioxidant properties. It is more evident when these oils are added to the diets of rats fed cholesterol. These positive properties are attributed mostly to the phenolic compounds of the studied oils. |
| Omega-3 fatty acid and cholesterol content of newly hatched chicks from alpha-linolenic acid enriched eggs Cherian, G. and J. S. Sim (1992), Lipids 27(9): 706-10. Abstract: Egg yolk was enriched with alpha-linolenic acid (18:3n-3) by feeding laying hens diets containing flax, canola or soybean seeds. Fertilized eggs were incubated and the fatty acid composition of whole body, liver, plasma, brain and the cholesterol content of plasma and liver tissue of the hatched chicks were studied. Eggs enriched with 18:2n-6 fatty acids by feeding hens diets containing sunflower seeds were used as the controls. Feeding flax enriched (P < 0.05) egg yolk and the developing progeny with 18:3n-3, 20:5n-3, 22:5n-3 and 22:6n-3. Feeding sunflower seeds resulted in an increase (P < 0.05) of 18:2n-6, 20:4n-6, 22:4n-6 and 22:5n-6. The predominant polyunsaturated fatty acid of the brain was docosahexaenoic acid (22:6n-3) which was higher (P < 0.05) in the flax and canola fed group. The cholesterol content of the liver tissue was lower (P < 0.05) in chicks hatched from hens fed flax seeds. This study indicates that 18:3n-3 and 18:2n-6 in the maternal diet are potent modulators of long-chain polyunsaturated n-3 or n-6 fatty acid and of cholesterol content in the developing progeny. |
| Omega-3 fatty acid intake results in a relationship between the fatty acid composition of LDL cholesterol ester and LDL cholesterol content in humans Clandinin, M. T., A. Foxwell, et al. (1997), Biochim Biophys Acta 1346(3): 247-52. Abstract: The relationship between the fatty acid composition of the low density lipoprotein (LDL) cholesterol ester and LDL cholesterol content was assessed in 26 free-living, normal subjects. Dietary intakes of 14:0, 16:0, 18:0, 18:1, 18:2omega6, 18:3omega3, 20:4omega6, 20:5omega3, 22:6omega3 were calculated from seven-day food records kept by each subject at baseline and after three months of supplementation with olive, flaxseed or fish oil, respectively. A randomized cross-over design was used. The fatty acid content of specific foods was calculated. Fasting blood samples, taken at the beginning and end of each supplementation period, were analyzed for the fatty acid content present in individual lipoproteins. There was a significant correlation between 20:5omega3 and 22:6omega3 intake and the content of these fatty acids in the LDL cholesterol ester fraction. During the fish oil treatment period the 16:0 and 18:0 content of the LDL cholesterol ester was highly predictive of LDL cholesterol content. This relationship was not observed during the baseline or placebo (olive oil) supplement period. |
| Omega-3 fatty acids in smooth muscle cell phospholipids increase membrane cholesterol efflux Dusserre, E., T. Pulcini, et al. (1995), Lipids 30(1): 35-41. Abstract: The aim of our work was to determine whether fatty acid modifications in smooth muscle cell phospholipids affect cholesterol efflux and desorption. 3HCholesterol was used to label cholesterol pools in the whole cell or selectively in the plasma membrane. Cells were incubated for 12 h in order to increase oleate, linoleate, arachidonate, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in phospholipids. Cholesterol efflux was monitored using native or tetranitromethane modified high-density lipoprotein3 (HDL3). When all cholesterol pools were labeled, the efflux from cells treated with different fatty acids were not different. Plasma membrane cholesterol efflux remained unchanged after oleate, linoleate or arachidonate treatments, but was markedly increased after EPA and DHA enrichment, both with native HDL3 and with tetranitromethane-high-density lipoprotein. These results suggest that the positive effects of n-3 fatty acid consumption on the atherosclerotic process could be linked in part to an increase in plasma membrane cholesterol efflux from vascular smooth muscle cells. |