Cholesterol Journal Articles

Record 13401 to 13420

Variability in cholesterol measurements: comparison of calculated and direct LDL cholesterol determinations
Schectman, G., M. Patsches, et al. (1996), Clin Chem 42(5): 732-7.
Abstract: Calculated low-density lipoprotein cholesterol (LDL-C) concentrations determined from the Friedewald equation have a large intraindividual CV, in part because the calculation incorporates the variability of cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglyceride measurements. We studied whether a new assay that measures LDL-C directly will reduce this variability and reduce the need for averaging serial specimens. Four blood samples were obtained 1 week apart from 35 mildly hypercholesterolemic subjects and analyzed for total cholesterol, triglycerides, and HDL-C. LDL-C was calculated by the Friedewald equation, and was also measured directly with a commercially available direct LDL-C assay. The intraindividual CV for the direct and calculated LDL-C assays were similar CV of direct LDL-C assay (mean +/- SE): 6.8 +/- 0.5% vs calculated LDL-C: 7.3 +/- 0.6%; difference 0.44%, 95% confidence interval: -0.7-1.5%. For both assays, at least two blood tests were required from each subject to reduce total variability of LDL-C to less than or equal to 5%. We conclude that the direct LDL-C assay did not reduce the variability in LDL-C compared with the conventional LDL-C calculation. However, it may have a specific role in lipid disorder evaluation and (or) monitoring when triglycerides are increased or the LDL-C value alone is needed.

Variability in response to a low-fat, low-cholesterol diet in children with elevated low-density lipoprotein cholesterol levels
Quivers, E. S., D. J. Driscoll, et al. (1992), Pediatrics 89(5 Pt 1): 925-9.
Abstract: The reduction of dietary cholesterol and fat lowers low-density lipoprotein cholesterol (LDL-C) and reduces risk of coronary heart disease in adults. The purpose of this study was to determine the individual variability of response of serum lipid and lipoprotein levels to a low-fat, low-cholesterol diet in children with elevated LDL-C levels. Thirty-two children (2 to 16 years of age) enrolled in a diet modification program, who had LDL-C levels of at least 110 mg/dL but normal triglyceride levels for their ages, were studied. Lipid levels and dietary nutrients were analyzed at the time of admission, and final assessments were made at least 3 months after entry. There was a significant correlation, for the group as a whole, between change in LDL-C concentration and change in grams of dietary saturated fat; however, there was marked individual variability in LDL-C response. There were no significant correlations between changes in LDL-C levels and changes in either total fat, polyunsaturated fat, or cholesterol intake. It is concluded that modest decreases in dietary saturated fat coincide with a lowering of LDL-C concentration, over a short term, in many children, but the degree of lowering varies considerably from one child to another. This variability is consistent with the concept that response of serum lipid levels to dietary changes is modified by genetic, metabolic, and other, as of yet, undefined variables.

Variability in the response of HDL cholesterol to exercise training in the HERITAGE Family Study
Leon, A. S., S. E. Gaskill, et al. (2002), Int J Sports Med 23(1): 1-9.
Abstract: In the HERITAGE Family Study, 675 sedentary, healthy, white and black men and women, aged 17 to 65 years, performed 20 weeks of supervised cycle ergometer exercise at the same relative intensity and weekly volume. As a group, subjects had normal mean baseline lipid levels for North Americans with the exception of below average high density lipoprotein cholesterol (HDL-C) levels. A significant mean increase in plasma HDL-C of 3.6 % was observed; however, there was marked variability in responsiveness to training, ranging from a mean 9.3 % decrease in Quartile 1 of HDL-C response to a mean 18 % increase in Quartile 4 (P < 0.0001 by ANOVA). Parallel changes in HDL(2)-C and HDL(3)-C, apolipoprotein A-I levels, and lipoprotein lipase activity were noted across quartiles. The change in HDL-C across quartiles was inversely related to baseline HDL-C (p < 0.0001) and to changes with training in plasma triglycerides (p = 0.0007). No significant differences in HDL-C response were observed across quartiles by sex, race, age, or increase in VO(2)max with training; however, weak positive associations were observed with age-adjusted education level and with reduction in abdominal fat and increase in VO(2)max at the ventilatory threshold following training. Multivariate regression analysis including baseline variables and training responses only accounted for 15.5 % of the variability in the HDL-C response to training. Thus, marked variability was found in the HDL-C response to the same endurance exercise training stimulus with only a modest amount of the response predictable by identified nongenetic factors.

Variable influence of kaempferol and myricetin on in vitro hepatocellular cholesterol biosynthesis
Gebhardt, R. (2003), Planta Med 69(12): 1071-4.
Abstract: Flavonoids, e. g., quercetin, luteolin, and taxifolin, are known to inhibit hepatocellular cholesterol biosynthesis. Surprisingly, we found that some flavonoids, namely kaempferol and myricetin, are able to considerably stimulate cholesterol biosynthesis, particularly within a low concentration range (between 0.1 and 10 microM), while they show a variable degree of inhibition at higher concentrations. Kaempferol 3-glucoside even stimulated cholesterol synthesis up to 100 microM. In contrast, kaempferol 7-neohesperidoside was ineffective. These effects were more pronounced in rat hepatocytes than in HepG2 cells except for myricetin which acted stimulatory even at high concentrations in HepG2 cells. These opposing effects on cholesterol biosynthesis are exerted in an indirect manner and seem possible though differential modulation of the complex regulation of HMGCoA reductase.

Variants in the cholesterol ester transfer protein and lipoprotein lipase genes are predictors of plasma cholesterol response to dietary change
Wallace, A. J., J. I. Mann, et al. (2000), Atherosclerosis 152(2): 327-36.
Abstract: There are no definitive explanations as to why individuals with hypercholesterolemia, a major cardiovascular risk factor, respond differently to dietary change. Fifty five free-living individuals completed a double crossover trial with two dietary regimens, a high saturated fat diet (providing 21% energy from saturated fat and 3% energy from polyunsaturated fat) and a high polyunsaturated fat diet (providing 11% energy as saturated fat and 10% energy as polyunsaturated fat), each phase continuing for 4 weeks. Extensive genotyping and several measures of dietary compliance have provided further insights regarding the determinants of extent of cholesterol response to changes in the nature of dietary fat. Individuals with the CETP B1B1 genotype and the LPL X447+ allele showed an average 0. 44 (95% CI: 0.22, 0.66) and 0.45 (95% CI: 0.18, 0.72) mmol/l greater change in total cholesterol, respectively, than those with one or more CETP B2 allele or homozygous for the LPL S447 allele when comparing diets high and low in saturated fat. Indices of dietary compliance including changes in reported saturated and polyunsaturated fat intake and change in triglyceride linoleate were not significantly different between the CETP genotypes. Change in reported saturated (r=0.36, P=0.04) and polyunsaturated (r=0.22, P=0. 05) fat intake and change in triglyceride linoleate (reflecting polyunsaturated fat intake) (r=0.21, P=0.07), also predicted total cholesterol response to dietary fat changes. In multivariate analyses, variation in the cholesterol ester transfer protein and lipoprotein lipase genes predicted response independent of measures of dietary compliance, suggesting that these two genes are important determinants of variation in cholesterol response to dietary change in free-living individuals.

Variants of the microsomal triglyceride transfer protein gene are associated with plasma cholesterol levels and body mass index
Ledmyr, H., F. Karpe, et al. (2002), J Lipid Res 43(1): 51-8.
Abstract: The microsomal triglyceride transfer protein (MTP) is required for the assembly and secretion of apolipoprotein B (apoB)-containing lipoproteins from liver and intestine. We set out to study the phenotypic modulation of all common genetic variants in the MTP gene. In addition, we aimed at characterizing the association between the various polymorphisms. A total of 564 healthy men were genotyped for the MTP -493 G/T, -400 A/T, and -164 T/C promoter polymorphisms, as well as the Q/H 95, I/T 128, Q/E 244, and H/Q 297 missense polymorphisms. The -493 G/T, -164 T/C, and I/T 128 polymorphisms showed to be in almost complete linkage disequilibrium. Subjects homozygous for the less common -493 T, -164 C, and T 128 alleles showed significantly lower plasma total and LDL cholesterol levels and plasma LDL apoB levels, and also significantly higher body mass index (BMI) and plasma insulin levels compared with carriers of the common alleles. The associations between plasma total cholesterol and MTP -493 genotype was verified in a cohort consisting of 1,117 disease-free control subjects of the West of Scotland Coronary Prevention Study (WOSCOPS). None of the other polymorphisms showed any significant change in either lipid and lipoprotein levels or anthropometric variables.In summary, two promoter polymorphisms and one missense polymorphism in the MTP gene alter plasma total and LDL cholesterol levels, plasma LDL apoB levels, BMI, and insulin levels. This may, in turn, have implications for genetic regulation of cardiovascular risk factors.

Variation at position 162 of peroxisome proliferator-activated receptor alpha does not influence the effect of fibrates on cholesterol or triacylglycerol concentrations in hyperlipidaemic subjects
Puckey, L. H. and B. L. Knight (2001), Pharmacogenetics 11(7): 619-24.
Abstract: The fibrate group of drugs are widely used to lower plasma lipid concentrations, especially in diabetic subjects. They exert their effects by activating peroxisome proliferator-activated receptor alpha (PPARalpha), which regulates the transcription of a number of genes involved in hepatic lipid metabolism. The discovery of polymorphisms in the PPARalpha gene raises the possibility that different variants could be associated with different responses to fibrate therapy. We have examined this in a random sample of 96 lipid clinic subjects who showed a wide range of response to fibrates. Of the known polymorphisms in PPARalpha, the only difference detected in this sample was the Leu/Val change at position 162. However, this change did not influence baseline plasma cholesterol or triacylglycerol concentrations, and was not associated with any difference in the effectiveness of fibrate treatment. Thus, there is no evidence that variation in the PPARalpha gene at position 162 is responsible for the differential response to fibrates in non-diabetic hyperlipidaemic subjects.

Variation at the cholesteryl ester transfer protein gene in relation to plasma high density lipoproteins cholesterol levels and carotid intima-media thickness
Kakko, S., M. Tamminen, et al. (2001), Eur J Clin Invest 31(7): 593-602.
Abstract: BACKGROUND: Cholesteryl ester transfer protein (CETP) plays a major role in lipoprotein metabolism. We have screened the CETP gene for mutations and polymorphisms regulating high density lipoproteins cholesterol (HDL-C) levels and the development of atherosclerosis, and found some polymorphisms (I405V and R451Q) to have minor effects. DESIGN: The purpose of this study was to investigate the combined effect of the several polymorphisms of the CETP gene so far found on HDL-C levels and carotid intima-media thickness (IMT), and, in addition, to study whether the recently found functional polymorphism in the promoter region of the CETP gene (C to A, - 629 relative to the first transcribed nucleotide) explains the previous associations due to linkage disequilibrium. The genotypes were determined in a population sample of 481 men and women. RESULTS: There were no significant differences in plasma CETP activity or carotid IMT between the genotypes of the promoter polymorphism. The women with the CC genotype of the promoter polymorphism had the lowest HDL-C levels (P < 0.001), but no such difference was seen in men. Detected polymorphisms of the CETP gene explained about 8% of the variation in HDL-C in women and about 7 and 10% of the variation in carotid IMT in women and men, respectively. The associations of the promoter, I405V and R451Q-A373P polymorphisms with HDL-C and carotid IMT seemed to be independent of each other. The associations with IMT were independent of total HDL-C levels, suggesting that HDL subfractions may have more effect on IMT. CONCLUSION: The CETP gene locus was found to be polymorphic and its polymorphisms explained a reasonable proportion of the variation in the degree of carotid atherosclerosis.

Variation at the hepatic lipase and apolipoprotein AI/CIII/AIV loci is a major cause of genetically determined variation in plasma HDL cholesterol levels
Cohen, J. C., Z. Wang, et al. (1994), J Clin Invest 94(6): 2377-84.
Abstract: Genetic factors have been shown to play an important role in determining interindividual variation in plasma HDL-C levels, but the specific genetic determinants of HDL cholesterol (HDL-C) levels have not been elucidated. In this study, the effects of variation in the genomic regions encoding hepatic lipase, apolipoprotein AI/CIII/AIV, and the cholesteryl ester transfer protein on plasma HDL-C levels were examined in 73 normotriglyceridemic, Caucasian nuclear families. Genetic factors accounted for 56.5 +/- 13% of the interindividual variation in plasma HDL-C levels. For each candidate gene, adjusted plasma HDL-C levels of sibling pairs who shared zero, one, or two parental alleles identical-by-descent were compared using sibling-pair linkage analysis. Allelic variation in the genes encoding hepatic lipase and apolipoprotein AI/CIII/AIV accounted for 25 and 22%, respectively, of the total interindividual variation in plasma HDL-C levels. In contrast, none of the variation in plasma HDL-C levels could be accounted for by allelic variation in the cholesteryl ester transfer protein. These findings indicate that a major fraction of the genetically determined variation in plasma HDL-C levels is conferred by allelic variation at the hepatic lipase and the apolipoprotein AI/CIII/AIV gene loci.

Variation in cholesterol levels
Tallis, G. A. and D. Buckett (1990), Med J Aust 153(9): 566.

Variation in cholesterol, lipoproteins and triglycerides after heart transplantation in children
Di Filippo, S., A. Sassolas, et al. (2001), Arch Mal Coeur Vaiss 94(5): 464-9.
Abstract: Total cholesterol, HDL and LDL-cholesterol and triglyceride levels may contribute to the development or progression of coronary artery disease of the transplanted heart. The aim of this retrospective study was to determine the short and long-term lipid profiles of transplanted children and to identify factors influencing these dyslipidemias. Twenty-three patients aged 9.5 +/- 5.9 years at cardiac transplantation were followed up for 5.8 +/- 3.1 years. All were on triple therapy with normal diets. The total cholesterol increased by 17% during the first year (4.47 +/- 1.01 mMol/l to 5.25 +/- 1.22 mMol/l at 1 year: p < 0.05) with a peak at 3 months of 5.31 +/- 1.28 mMol/l correlating with the dosage of prescribed corticosteroids. LDL-cholesterol levels increased by 20% during the first year (2.26 +/- 0.67 mMol/l to 3.29 +/- 0.99 mMol/l at 1 year: p = 0.018). HDL-cholesterol levels increased from 1.02 +/- 0.27 mMol/l to a maximum of 1.55 +/- 0.4 mMol/l at 1 year, p < 0.05. Lipoprotein A1, a protecting sub-fraction of HDL, did not change significantly. Changes in triglyceride levels were not significant despite a tendency to hypertriglyceridaemia in the early phases. After one year, serum cholesterol and lipoprotein levels remained higher than the initial values. These results show that cardiac transplant children are exposed to the risk of atherogenic hyperlipidaemia and require systematic lipid profile monitoring, dietary advice and lipid lowering drugs.

Variation in egg yolk cholesterol concentration between and within breeds of the domestic fowl
Hall, L. M. and J. C. McKay (1992), Br Poult Sci 33(5): 941-6.
Abstract: 1. The pattern of variation for egg yolk cholesterol concentration between 5 commercial egg layer lines and a cross of Gallus domesticus is described. 2. Yolk cholesterol concentration in the cross was lower than in the lines, and 6.7% lower than the midparent value. 3. It is proposed that the reduced yolk cholesterol concentration of the cross may be a consequence of heterosis, although sex-linkage and/or maternal effects cannot be discounted. 4. The difference between the cross and parental lines is consistent with a physiological relationship between yolk cholesterol concentration and rate of egg production, but not between yolk cholesterol concentration and yolk weight.

Variation in plasma cholesterol concentration over time in the domestic fowl
Hall, L. M. and J. C. McKay (1994), Br Poult Sci 35(4): 631-4.
Abstract: 1. Variations in the concentration of plasma cholesterol available to the developing oocyte over a three week period in Gallus domesticus are described. 2. There are small changes in concentration between weeks for individual birds, but no changes between consecutive days within weeks or times within days. 3. It is recommended that future attempts to assess the relationship between variation in blood and yolk cholesterol concentrations estimate blood cholesterol concentration from two samples taken a week apart.

Variation in plasma cholesterol response to dietary change
Wallace, A. J., J. I. Mann, et al. (1999), Nutr Metab Cardiovasc Dis 9(4): 176-83.
Abstract: BACKGROUND AND AIMS: Previous studies have suggested that some individuals show an appreciably larger change in total cholesterol in response to dietary change (hyper-responders) than others (minimal responders), and also that some people are more likely to respond consistently. We have examined the role of individual dietary compliance in determining total cholesterol response to changes in the nature of dietary fat. METHODS AND RESULTS: Participants completed a randomised double dietary crossover trial with a diet high in saturated fat and a diet high in polyunsaturated fat. Each period continued for four weeks without washouts. Plasma lipoproteins were measured at the end of each period. Dietary compliance was assessed by change in the reported polyunsaturated:saturated fat ratio calculated from three-day diet records, and change in polyunsaturated fat intake, determined by change in plasma triglyceride linoleate. A wide range of individual responses was observed with no evidence of two distinct populations of hyper- and minimal responders. Variation in response to the three crossovers appeared to be due mainly to variation in compliance. CONCLUSIONS: The results of this study do not support earlier suggestions of two separate populations of hyper and minimal responders to change in the nature of dietary fat, rather there is a graded range of response. In a free-living population, the extent to which individuals comply with dietary advice varies considerably and this contributes to the magnitude of cholesterol response as well as consistency on repeated dietary challenges.

Variation in serum cholesterol level in the same person: what is the true value and when is it called a significant change?
Hendriksen, I. J., P. D. Bezemer, et al. (1992), Ned Tijdschr Geneeskd 136(31): 1507-11.
Abstract: The blood cholesterol level is not constant over time. Changing values may be found when rechecking high values, especially in patients on a diet or receiving medication. Repeated measurements are necessary. It will then be possible to estimate the 'true mean value'. This is the theoretical average of a large number of measurements taken from one person. The study concentrated on the intra-individual variation of the serum cholesterol and the consequences for screening and follow-up. For this purpose, during a period of four weeks, cholesterol levels were measured 12 times in 33 men aged 25-40. The mean coefficient of variation was 5.7%, with wide differences between participants, ranging from 2.9% to 9.8%. The position of the 'true mean value' was estimated (with 90% confidence), after I resp. 3 determinations. These findings have consequences for the classification of subjects in the different risk categories as defined in the Dutch Cholesterol Consensus. It is also possible to determine if, after a period of intervention, there is a significant decline in the cholesterol level. Roughly, a decline of 10-12% indicates a significant difference.

Variation in the cholesterol/phospholipid ratio in human spermatozoa and its relationship with capacitation
Hoshi, K., T. Aita, et al. (1990), Hum Reprod 5(1): 71-4.
Abstract: The cholesterol/phospholipid (C/PL) ratio was determined for spermatozoa from eight men with normal semen parameters. There was a close correlation between the C/PL ratio and the rate of sperm capacitation as assessed by the hamster egg penetration test. A lower C/PL ratio correlated with a faster capacitation time. This supports the notion that the loss or reduction of membrane cholesterol constitutes an important step of capacitation in human spermatozoa.

Variation in the low density lipoprotein receptor gene is associated with differences in plasma low density lipoprotein cholesterol levels in young and old normal individuals from Italy
Humphries, S., D. A. Coviello, et al. (1991), Arterioscler Thromb 11(3): 509-16.
Abstract: We have used four restriction fragment length polymorphisms (RFLPs) of the human low density lipoprotein receptor (LDL-R) gene, detected by the restriction enzymes Ava II, Pvu II, and ApaLI (5' and 3'), to study the effect of variation at this gene locus in determining plasma cholesterol and LDL cholesterol levels. Two hundred eighty-nine normolipidemic individuals were studied from the Liguria region of Italy. The Pvu II RFLP was significantly associated with differences in plasma total and LDL cholesterol levels, explaining 9.6% of the sample variance in LDL cholesterol levels. The other RFLPs, which are in strong linkage disequilibrium with the Pvu II RFLP, were associated with smaller effects on LDL cholesterol. The Pvu II allele, distinguished by the presence of the variable cutting site (P2 allele), was associated with lower levels of total and LDL cholesterol, and the frequency of the P2 allele was significantly reduced in individuals with LDL cholesterol levels higher than the 75th percentile. The frequency of the P2 allele was significantly higher in the group of individuals over 65 years old, and in this group the P2 allele was also associated with a similar reduction in LDL cholesterol levels. Because of linkage disequilibrium, only four RFLP haplotypes were common in this sample. Of these, only the haplotype P2A2VI (relative frequency, 0.269) was associated with a reduction in LDL cholesterol (average excess, -11.5 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Variation in the Reflotron method of cholesterol measurement
Lefebvre, R. C., P. Gubata, et al. (1990), Am J Cardiol 65(13): 916-7.

Variation of plasma cholesterol levels in rats fed trans fatty acids or cis fatty acids
Chiang, M. T. and Y. S. Lu (1996), Int J Vitam Nutr Res 66(3): 263-9.
Abstract: To investigate the effect of dietary trans fatty acids on plasma and liver lipids, 16 Sprague Dawley male rats fed the hydrogenated soybean oil (Trans fat) or Cis fat from olive oil with two similar dietary fatty acid ratios for 9 weeks were studied. Higher plasma total cholesterol and LDL (low density lipoprotein) cholesterol levels were observed in rats fed trans fat diet when compared with rats fed the cis fat diet after 2 weeks of feeding. However, no significant changes in plasma total cholesterol and LDL cholesterol levels were found in rats of both dietary groups at 4-weeks of feeding. Rats fed trans fatty acids had lower plasma total cholesterol, LDL and VLDL (very low density lipoprotein) cholesterol levels at the end of the experimental period. Although significantly (p < 0.05) lower liver triacylglycerol contents were found in rats fed trans fat diet, no significant (p > 0.05) changes in liver cholesterol and phospholipids contents were observed in rats after trans fatty acids treatment. It is interesting that lower saturated to polyunsaturated ratios in fatty acid composition of plasma VLDL total lipids were found in rats fed trans fat diet. Results from this study suggest that the changes in plasma lipoprotein cholesterol in rats fed trans fatty acids might be related to the long or the short term study, and dietary trans fatty acids may alter the plasma lipoprotein metabolism in rats.

Variations in cholesterol management practices of U.S. physicians
Stafford, R. S., D. Blumenthal, et al. (1997), J Am Coll Cardiol 29(1): 139-46.
Abstract: OBJECTIVES: This study sought to evaluate national cholesterol management practices of U.S. physicians. BACKGROUND: Past studies show that nonclinical factors affect physician practices. We tested the hypothesis that physician and patient characteristics influence cholesterol management. METHODS: We used a stratified, random sample of 2,332 office-based physicians providing 56,215 visits to adults in the 1991-1992 National Ambulatory Medical Care Surveys. We investigated physicians' reporting of cholesterol-related screening, counseling or medications during office visits and used multiple logistic regression to assess independent predictors. RESULTS: An estimated 1.12 billion adult office visits occurred in 1991 and 1992 (95% confidence interval 1.06 to 1.18 billion). For the 1.03 billion visits by patients without reported hyperlipidemia, cholesterol screening (2.8% of visits) and counseling (1.2%) were not frequent. The likelihood of screening increased with older age, cardiovascular disease risk factors, white race and private insurance. We estimate that only 1 in 12 adults received cholesterol screening annually. In the 85 million visits by patients with hyperlipidemia, cholesterol testing was reported in 22.9%, cholesterol counseling in 34.4% and lipid-lowering medications in 23.1%. Testing was more likely in diabetic and nonobese patients. Counseling was more likely with younger age, cardiovascular disease and private insurance. Medications use was associated with cardiovascular disease, Northeast region of the United States, nonobese patients and visits to internists. Physician practices did not differ by patient gender. CONCLUSIONS: Although clinical conditions strongly influence cholesterol management, the appropriateness of variations noted by payment source, geographic region and physician specialty deserve further evaluation. These variations and the low estimated volume of services suggest that physicians have not fully adopted recommended cholesterol management practices.

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