Cholesterol Journal Articles

Record 3421 to 3440

Combined influence of cholesterol and synthetic amphiphillic peptides upon bilayer thickness in model membranes
Nezil, F. A. and M. Bloom (1992), Biophys J 61(5): 1176-83.
Abstract: Deuterium (2H) NMR was used to study bilayer hydrophobic thickness and mechanical properties when cholesterol and/or synthetic amphiphillic polypeptides were added to deuterated POPC lipid bilayer membranes in the liquid-crystalline (fluid) phase. Smoothed acyl chain orientational order profiles were used to calculate bilayer hydrophobic thickness. Addition of 30 mol% cholesterol to POPC at 25 degrees C increased the bilayer thickness from 2.58 to 2.99 nm. The peptides were chosen to span the bilayers with more or less mismatch between the hydrophobic peptide length and membrane hydrophobic thickness. The average thickness of the pure lipid bilayers was significantly perturbed upon addition of peptide only in cases of large mismatch, being increased (decreased) when the peptide hydrophobic length was greater (less) than that of the pure bilayer, consistent with the "mattress" model of protein lipid interactions (Mouritsen, O.G., and M. Bloom. 1984. Biophys. J. 46:141-153). The experimental results were also used to examine the combined influence of the polypeptides and cholesterol on the orientational order profile and thickness expansivity of the membranes. A detailed model for the spatial distribution of POPC and cholesterol molecules in the bilayers was proposed to reconcile the general features of these measurements with micromechanical measurements of area expansivity in closely related systems. Experiments to test the model were proposed.

Combined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: influence of apolipoprotein A-I concentration and vesicle composition
Gudheti, M. V., S. P. Lee, et al. (2005), Biochemistry 44(19): 7294-304.
Abstract: We report the combined effects of phospholipase C (PLC), a pronucleating factor, and apolipoprotein A-I (apo A-I), an antinucleating factor, in solutions of model bile. Results indicate that apo A-I inhibits cholesterol nucleation from unilamellar lecithin vesicles by two mechanisms. Initially, inhibition is achieved by apo A-I shielding of hydrophobic diacylglycerol (DAG) moieties so as to prevent vesicle aggregation. Protection via shielding is temporary. It is lost when the DAG/apo A-I molar ratio exceeds a critical value. Subsequently, apo A-I forms small (approximately 5-15 nm) complexes with lecithin and cholesterol that coexist with lipid-stabilized (400-800 nm) DAG oil droplets. This microstructural transition from vesicles to complexes avoids nucleation of cholesterol crystals and is a newly discovered mechanism by which apo A-I serves as an antinucleating agent in bile. The critical value at which a microstructural transition occurs depends on binding of apo A-I and so varies with the cholesterol mole fraction of vesicles. Aggregation of small, unilamellar, egg lecithin vesicles (SUVs) with varying cholesterol composition (0-60 mol %) was monitored for a range of apo A-I concentrations (2 to 89 microg/mL). Suppression of aggregation persists so long as the DAG-to-bound-apo A-I molar ratio is less than 100. A fluorescence assay involving dansylated lecithin shows that the suppression is an indirect effect of apo A-I rather than a direct inhibition of PLC enzyme activity. The DAG-to-total apo A-I molar ratio at which suppression is lost increases with cholesterol because of differences in apo A-I binding. Above this value, a microstructural transition to DAG droplets and lecithin/cholesterol A-I complexes occurs, as evidenced by sudden increases in turbidity and size and enhancement of Forster resonance energy transfer; structures are confirmed by cryo TEM.

Combined measurement of serum albumin and high-density lipoprotein cholesterol strongly predicts mortality in frail older nursing-home residents
Zuliani, G., S. Volpatol, et al. (2004), Aging Clin Exp Res 16(6): 472-5.
Abstract: BACKGROUND AND AIMS: The aim of this study was to verify the hypothesis that a combined measurement of albumin and HDL-C might predict total mortality in institutionalized frail older residents. METHODS: Participants were 344 older subjects (272 F, 72 M), living in the "Istituto Riposo Anziani" (I.R.A.), a nursing-home located in Padova, North-east Italy. Functional status, comorbidity, and clinical chemistry parameters were evaluated at entry. All-cause mortality was evaluated after 2 and 4 years. The sample was divided into 4 groups by using the 50 degrees percentile of albumin and HDL-C as cut-off value. The mortality odds ratio (OR) was estimated by multivariate logistic regression analysis. RESULTS: Total mortality was 36.8% after 2 years and 51.8% after four years. A trend toward an increase in mortality from group 1 to 4 was observed (p for trend: 0.01). The OR for 2 and 4 years mortality was 3.83 (95% CI 1.86-7.58) and 2.66 (95% CI 1.37-5.17), respectively, in group 4 compared with group 1, after adjustment for age, gender, number of chronic diseases, functional status, BMI, diabetes, dementia, stroke, CHD, CHF, hypertension, depression, COPD, and total cholesterol levels. CONCLUSIONS: Among frail older nursing-home residents, simple measurement of serum albumin and HDL-C levels may be useful in identifying varying degrees of frailty.

Combined Monte Carlo and molecular dynamics simulation of hydrated lipid-cholesterol lipid bilayers at low cholesterol concentration
Chiu, S. W., E. Jakobsson, et al. (2001), Biophys J 80(3): 1104-14.
Abstract: We have applied a hybrid equilibration and sampling procedure for the atomic level simulation of a hydrated lipid bilayer to systems consisting of dipalmitoyl phosphatidylcholine (DPPC) and cholesterol, and palmitoyl-oleyl phosphatidylcholine (POPC) at low (approximately 6%) cholesterol concentration. The procedure is applied to bilayers of 94 molecules of DPPC, 6 molecules of cholesterol, and 3205 water molecules, and to bilayers of 120 molecules of POPC, 8 molecules of cholesterol, and 4268 water molecules, at a temperature of 325 K. After equilibration, three separate 400-ps continuous molecular dynamics runs, separated by 10,000 configurational bias Monte Carlo steps, were carried out for each system. Properties of the systems were calculated and averaged over the three separate runs. Results of the simulations are presented and compared with experimental data and with other recent simulations of DPPC and cholesterol, and of pure DPPC, and pure POPC. Certain properties of the bilayers are indistinguishable from cholesterol-free bilayers, including lateral diffusion and electron density. Other properties, most notably the order parameter profile, show the effect of cholesterol even at low concentrations.

Combined treatment of probucol with diltiazem regresses atherosclerosis induced by 196 cholesterol diet in rabbit aorta
Kouzuma, R., H. Tasaki, et al. (1995), Artery 21(6): 337-51.
Abstract: To clarify whether probucol, an antioxidant, or diltiazem, a Ca2+ antagonist, favorably affect the regression of established atherosclerosis, rabbits were fed a 1% cholesterol diet for 10 weeks, then a standard diet for an additional 25 weeks (regression period). During the regression period, rabbits were grouped into a saline (S) group (n=8, 1 ml saline/d), a probucol (P) group (n=8, 1000 mg/d probucol), or a probucol and diltiazem (P+D) group (n=8, probucol 1000 mg/d in diet and diltiazem 30 mg/d). We measured cholesterol in serum, lipoprotein fractions, and serum triglyceride or phospholipid concentration and found no significant differences among the three groups at 10, 15, or 35 weeks. After 10 weeks of the atherogenic diet, the ratio of macroscopic atherosclerotic lesions in aortic intima rose to 36.6 + or - 5.6%. After the regression period, the S group developed more atherosclerotic lesions (48.6 + or - 6.4%). The P+D and P groups, however, had decreased scores of 24.3 + or - 5.5% (p<0.05 vs. S) and 32.3 + or - 5.6%, respectively. Moreover, these decreased scores were well correlated with the decrease in aortic tissue lipid compositions, but not the parameters for extracellular matrices. We concluded that P+D or P therapy might be effective in regressing established atherosclerosis by removing lipid contents but not extracellular matrices.

Comet-tail artifact from cholesterol crystals: observations in the postlithotripsy gallbladder and an in vitro model
Shapiro, R. S. and F. Winsberg (1990), Radiology 177(1): 153-6.
Abstract: The "comet tail" is a well-known ultrasound artifact that appears as a series of parallel bands radiating from a source. This artifact was observed in the gallbladder lumen in eight of 10 patients after extracorporeal shock wave lithotripsy of radiolucent calculi. To investigate the cause of the comet tail artifact, cholesterol crystals were studied in an in vitro model. The comet-tail appearance was reproduced in vitro and was found to be directly related to the interrogating frequency and the size of the crystal aggregates. The authors conclude that cholesterol crystals can serve as the source of the comet-tail artifact secondary to reverberation within the crystals.

Commentary: Developmental origins of raised serum cholesterol
Barker, D. J. (2003), Int J Epidemiol 32(5): 876-7.

Commentary: The association between height growth and cholesterol levels during puberty: implications for adult health
Hardy, R. and C. Langenberg (2003), Int J Epidemiol 32(6): 1110-1.

Comments on 1,6-diphenyl-1,3,5-hexatriene fluorescence decrease at critical cholesterol concentration in phospholipid membranes
Parasassi, T. and E. Gratton (1996), Biophys J 70(3): 1560-2.

Comments on some changes in plasma cholesterol and vitamin E when different fats are fed
Horwitt, M. K. (1991), J Nutr 121(8): 1293.

Comments on 'Sustained reduction in circulating cholesterol in adult hypopituitary patients given low dose titrated growth hormone replacement therapy: a two-year study' by Florakis et aL (2000)
Cesana, B. M. (2001), Clin Endocrinol (Oxf) 55(5): 695-7.

Common and rare ABCA1 variants affecting plasma HDL cholesterol
Wang, J., J. R. Burnett, et al. (2000), Arterioscler Thromb Vasc Biol 20(8): 1983-9.
Abstract: Mutations in ABCA1, a member of the ATP-binding cassette family, have been shown to underlie Tangier disease (TD) and familial hypoalphalipoproteinemia (FHA), which are genetic disorders that are characterized by depressed concentrations of plasma high density lipoprotein (HDL) cholesterol. An important question is whether common variants within the coding sequence of ABCA1 can affect plasma HDL cholesterol in the general population. To address this issue, we developed a screening strategy to find common ABCA1 variants. This strategy involved long-range amplification of genomic DNA by using coding sequences only, followed by deep sequencing into the introns. This method helped us to characterize a new set of amplification primers, which permitted amplification of virtually all of the coding sequence of ABCA1 and its intron-exon boundaries with a single DNA amplification program. With these new sequencing primers, we found 3 novel ABCA1 mutations: a frameshift mutation (4570insA, A1484S-->X1492), a missense mutation (A986D) in a TD family, and a missense mutation (R170C) in aboriginal subjects with FHA. We also used these sequencing primers to characterize 4 novel common amino acid variants in ABCA1, in addition to 5 novel common silent variants. We tested for association of the ABCA1 I/M823 variant with plasma HDL cholesterol in Canadian Inuit and found that M823/M823 homozygotes had significantly higher plasma HDL cholesterol compared with subjects with the other genotypes. The results provide proof of principle of the effectiveness of this approach to identify both rare and common ABCA1 genomic variants and also suggest that common amino acid variation in ABCA1 is a determinant of plasma HDL cholesterol in the general population.

Common cholesteryl ester transfer protein mutations, decreased HDL cholesterol, and possible decreased risk of ischemic heart disease: The Copenhagen City Heart Study
Agerholm-Larsen, B., A. Tybjaerg-Hansen, et al. (2000), Circulation 102(18): 2197-203.
Abstract: BACKGROUND: Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl ester from HDL in exchange for triglycerides in apolipoprotein B-containing lipoproteins. METHODS AND RESULTS: We studied 2 common mutations in CETP, A373P and R451Q, in 8467 healthy women and men from the Danish general population and in 1636 Danish women and men with ischemic heart disease. The prevalence of 373P and 451Q was 0.10 and 0.07, respectively, for heterozygous carriers and 0.003 and 0.002, respectively, for homozygous carriers. All carriers of the 451Q allele also carried the 373P allele. HDL cholesterol in female noncarriers, heterozygotes, and homozygotes of 373P was 1.74+/-0.01 (mean+/-SE), 1.62+/-0.02, and 1.38+/-0.09 mmol/L, respectively (ANOVA, P:<0.001). In men, equivalent values were 1.40+/-0.01, 1.26+/-0.02, and 1.19+/-0.09 mmol/L, respectively (ANOVA, P:<0.001). HDL cholesterol decreased similarly as a function of 451Q genotypes and all 373P/451Q genotype combinations. Furthermore, apolipoprotein AI and the HDL cholesterol/apolipoprotein AI ratio was also lower in carriers of either of these mutations for both sexes. Finally, the CETP genotype was not associated with risk of ischemic heart disease unless we adjusted for HDL cholesterol: female heterozygous and homozygous carriers versus noncarriers had 36% lower risk of ischemic heart disease (95% CI 4% to 57%); in male carriers, we observed a similar trend. CONCLUSIONS: The A373P/R451Q polymorphism in CETP is associated with decreases in HDL cholesterol of 0.12 to 0.36 mmol/L in women and 0.14 to 0.21 mmol/L in men and possibly with a paradoxical 36% decrease in the risk of ischemic heart disease in women.

Common mutations in the lipoprotein lipase gene (LPL): effects on HDL-cholesterol levels in a Chinese Canadian population
McGladdery, S. H., S. N. Pimstone, et al. (2001), Atherosclerosis 156(2): 401-7.
Abstract: Background: favorable lipid profiles including low total serum cholesterol (TC), TC/HDL-cholesterol (HDL-C) ratio and elevated HDL-C levels have been previously reported in Chinese living in China. More recent data, however, suggests a changing trend toward decreased HDL-C and increased TC and LDL cholesterol (LDL-C) in Chinese populations. Environmental factors likely contribute, in part, to these findings. However, genetic factors contributing to lipoprotein metabolism may also play a role in determining the lipid/lipoprotein phenotype observed in Chinese populations. Lipoprotein lipase (LPL) mutations have been associated with altered HDL-C concentrations in Caucasians but have not yet been studied in a large population of Chinese descent. Methods: 1577 Chinese Canadians of Cantonese descent were recruited for a cardiovascular risk factor study. The frequency and effect of three LPL gene polymorphisms Asp9Asn (D9N, n=374), Asn291Ser (N291S, n=321) and Ser447-Ter (S447X, n=403) on serum HDL-C concentrations was assessed. All the three polymorphisms have been shown to alter HDL-C levels in different Caucasian populations. Results: lower TC, LDL-C, and TG and higher HDL-C were observed in both male and female Chinese Canadian subjects compared to other population samples. The D9N and N291S LPL polymorphisms were identified in 1/374 (0.3%) and 5/321 (1.6%) subjects, respectively. Carrier frequency of the S447X mutation was (102/403) 25.3%. This S447X polymorphism was observed with higher frequency in males with HDL-C levels in the highest tertile compared with those in the lowest HDL-C tertile (carrier frequencies 37.3 vs. 19.4%) (P=0.046). Conclusion: in this cohort of Chinese Canadians, the serum lipid profiles were more favorable than what has been reported for Caucasian Canadians. A favorable spectrum of polymorphisms in the LPL gene may mitigate the adverse effects of western lifestyle on plasma lipoproteins in this cohort of Cantonese Canadians.

Common polymorphism in promoter of microsomal triglyceride transfer protein gene influences cholesterol, ApoB, and triglyceride levels in young african american men: results from the coronary artery risk development in young adults (CARDIA) study
Juo, S. H., Z. Han, et al. (2000), Arterioscler Thromb Vasc Biol 20(5): 1316-22.
Abstract: The microsomal triglyceride transfer protein (MTP) plays a key role in the assembly of apolipoprotein B (apoB)-containing lipoproteins. We investigated the relation between lipid profiles and a common functional polymorphism (-493G/T) of the MTP gene in a large sample of young black men in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. We performed serial cross-sectional analyses on lipids of 586 black men in 5 exams over 10 years of follow-up. Total cholesterol, LDL cholesterol, and apoB levels were very similar between the GT and GG genotypes; therefore, the GT and GG genotypes were combined as 1 group when the 3 phenotypes were analyzed. The results from ANCOVA showed that the TT group (prevalence 7%) had higher levels of apoB-related lipids than did the GT+GG group: the difference in total cholesterol ranged from 2 (P=0.79) to 19 (P=0.002) mg/dL in exams 1 to 5; the difference in LDL cholesterol ranged from 10 (P=0.14) to 17 (P=0.003) mg/dL in exams 1 to 4, but in examination 5, the difference became negligible. The TT group had higher levels of apoB, measured in only 2 exams, by 6 (P=0.12) and 9 (P=0.03) mg/dL. The TT group had higher levels of triglycerides than did the TG or GG group by 3 to 34 (P=0.02 to approximately 0.003) mg/dL in all 5 exams. HDL cholesterol and apolipoprotein A-I levels were similar among the 3 genotypes. Our serial cross-sectional analyses indicated that the TT genotype was associated with higher levels of total cholesterol, LDL cholesterol, triglycerides, and apoB in young black men. The broad effect of this polymorphism on several atherogenic traits suggests that the MTP gene could be influential in atherosclerosis.

Common promoter C516T polymorphism in the ApoB gene is an independent predictor of carotid atherosclerotic disease in subjects presenting a broad range of plasma cholesterol levels
Sposito, A. C., S. Gonbert, et al. (2004), Arterioscler Thromb Vasc Biol 24(11): 2192-5.
Abstract: OBJECTIVE: A common polymorphism in the promoter of the apolipoprotein B (apoB) gene, a C to T change at position -516, increases the transcription rate of apoB, resulting in elevated circulating levels of low-density lipoprotein (LDL) cholesterol. METHODS AND RESULTS: We tested the hypothesis that carriers of the -516T allele, who may display consistent elevation in plasma cholesterol over their lifetime, may present more extensive atherosclerotic disease than noncarriers. Genotyping of the apoB 516 C/T promoter polymorphism was performed in 326 subjects at low cardiovascular risk. Homozygotes for allele T displayed higher plasma levels of apoB and LDL than did heterozygotes. Furthermore, both homozygotes and heterozygotes for allele T exhibited higher plasma levels of apoB and LDL than did homozygotes for allele C (P<0.0001). In addition, homozygotes for allele T displayed higher carotid intima-media thickness (IMT) than subjects who were heterozygous. Moreover, both groups had higher carotid IMT than subjects of genotype -516C/C (P<0.001). Only age, high-density lipoprotein, and the presence of allele T were identified as independent predictors of the presence of carotid plaque. No association existed between the polymorphism and plasma concentrations of triglycerides, high-density lipoprotein, or apoAI. CONCLUSIONS: Our data indicate that a C to T change at position -516 of the apoB gene is independently associated with the presence of carotid atherosclerotic disease. Identification of the -516C/T polymorphism may therefore contribute to the estimation of overall cardiovascular risk.

Common variants in the gene encoding ATP-binding cassette transporter 1 in men with low HDL cholesterol levels and coronary heart disease
Brousseau, M. E., M. Bodzioch, et al. (2001), Atherosclerosis 154(3): 607-11.
Abstract: HDL cholesterol (HDL-C) deficiency is the most common lipid abnormality observed in patients with premature coronary heart disease (CHD). Recently, our laboratory and others demonstrated that mutations in the ATP-binding cassette transporter 1 (ABCA1) gene are responsible for Tangier disease, a rare genetic disorder characterized by severely diminished plasma HDL-C concentrations and a predisposition for CHD. To address the question of whether common variants within the coding sequence of ABCA1 may affect plasma HDL-C levels and CHD risk in the general population, we determined the frequencies of three common ABCA1 variants (G596A, A2589G and G3456C) in men participating in the Veterans Affairs Cooperative HDL Cholesterol Intervention Trial (VA-HIT), a study designed to examine the benefits of HDL raising in men having low HDL-C (< or =40 mg/dl) and established CHD, as well as in CHD-free men from the Framingham Offspring Study (FOS). Allele frequencies (%) in VA-HIT were 31, 16, and 4 for the G596A, A2589G, and G3456C variants, respectively, versus 27, 12, and 2 in FOS (P<0.03). None of the variants were significantly associated with plasma HDL-C concentrations in either population; however, in VA-HIT, the G3456C variant was associated with a significantly increased risk for CHD end points, suggesting a role for this variant in the premature CHD observed in this population.

Common variants in the promoter of the hepatic lipase gene are associated with lower levels of hepatic lipase activity, buoyant LDL, and higher HDL2 cholesterol
Zambon, A., S. S. Deeb, et al. (1998), Arterioscler Thromb Vasc Biol 18(11): 1723-9.
Abstract: Increased hepatic lipase (HL) activity is associated with small, dense, low density lipoprotein (LDL) and low high density lipoprotein2 (HDL2) cholesterol (-C) levels. A polymorphism in the promoter region of the HL gene (LIPC) is associated with HDL-C levels. To test whether this association is mediated by differences in HL activity between different LIPC promoter genotypes, the LIPC promoter polymorphism at position -250 (G-->A), HL activity, LDL buoyancy, and HDL-C levels were studied in white normolipidemic men and men with coronary artery disease (CAD). The less common A allele (frequency=0.21 and 0.25 in normal and CAD subjects, respectively) was associated with lower HL activity (P<0.005 by ANOVA) and buoyant LDL particles (P

Community cholesterol screening. Impact of labeling on participant behavior
Gordon, R. L., M. J. Klag, et al. (1990), Arch Intern Med 150(9): 1957-60.
Abstract: To investigate the effect of screening for an elevated cholesterol level and compliance with follow-up recommendations, we surveyed 375 participants in a free screening program at a shopping mall walk-in clinic. One hundred thirty-nine participants (37%) had desirable (less than 5.17 mmol/L less than 200 mg/dL), 135 (36%) had borderline (5.17 to 6.18 mmol/L 200 to 239 mg/dL), and 101 (27%) had high (greater than 6.18 mmol/L greater than 239 mg/dL) cholesterol levels. Persons in the borderline and high categories were instructed to see their physicians within 2 months for confirmation of their levels. Of the 338 (90%) who responded to a follow-up questionnaire at 3 months, 8 (7%) in the desirable, 23 (22%) in the borderline, and 44 (50%) in the high group had been to see physicians concerning their cholesterol levels since the screening. In multiple logistic regression analyses only cholesterol category at time of screening, current use of antihypertensive drugs, history of coronary heart disease, and history of a high cholesterol level were associated with physician follow-up. Our results suggest that labeling persons as being at high rather than borderline risk results in greater physician follow-up.

Community cholesterol screening: medical follow-up in subjects identified with high plasma cholesterol levels
Morris, C. D., V. D. Menashe, et al. (1990), Prev Med 19(5): 493-501.
Abstract: Population screening or plasma cholesterol is an effective method of detecting hypercholesterolemia; however, follow-up and treatment are essential components of such a program. After a city-wide screening in 1987 of more than 19,872 persons, using a mailed survey with a response rate of 48%, we evaluated subsequent actions of 3,078 individuals with high plasma cholesterol levels. Slightly more than half the population was aware of high blood cholesterol levels prior to the time of screening and apparently used the program for follow-up. Overall, after the screening, 65% consulted a physician within 5 months of screening and blood cholesterol levels were remeasured in 80% of the sample. Procrastination and expense were cited as the primary reasons for failing to consult a physician. If screening is to be effectively utilized as a means of reducing the prevalence of high plasma cholesterol levels, diligent follow-up must be made of all individuals identified to be at increased risk on the basis of their initial values.

Cholesterol Articles and Abstracts

Cholesterol Journal Articles