Lipoprotein Cholesterol Subfractions Research Articles

The effect of the Anti-Estrogen Tamoxifen on Cardiovascular Risk Factors in Normal Postmenopausal Women

Grey, Andrew B.; Stapleton, Joanne P.; Evans, Margaret C.; Reid, Ian R. Author Information

Employment and Coronary Risk in Women at Midlife: A Longitudinal Analysis

This study investigated the relation between employment and cholesterol in 541 women aged 42-50 years who resided in Allegheny County, Pennsylvania, in 1985-1988. Employment, health-related variables, and cholesterol were assessed at baseline and 3 years later. At baseline, employed and nonemployed women did not differ in cholesterol or health behaviors. However, women employed at baseline had a significant decrease in total high density lipoprotein cholesterol (1.9 mg/dl) and high density lipoprotein2 cholesterol subfraction (3.2 mg/dl) at follow-up. Those who were employed at both assessments had the lowest high density lipoprotein cholesterol at follow-up. These effects could not be accounted for by sociodemographics or employment quality variables. Post hoc analyses were conducted to examine health behaviors as a potential mechanism to account for the association between employment status and cholesterol. Over the study period, those who were employed at baseline were less likely to increase exercise and more likely to gain weight than those who were not employed at baseline. With menopause-related changes in metabolism, this can result in detrimental effects for cholesterol levels and coronary health. The results highlight the importance of longitudinal assessment in the study of employment and health.

Effects of ??-3 and ??-6 Fatty Acid???Rich Oils on the Cardiovascular System of Thermally Injured Rabbits: Changes in Plasma Triglycerides, Plasma Cholesterol, Relative Blood Viscosity, Platelet Count, and Bleeding Time

New Zealand white male rabbits were studied to determine how supplements of soybean oil, soybean + MaxEPA oil, or MaxEPA oil affected their cardiovascular status when they were burned. Plasma triglyceride concentrations increased at 2 hours after burn injury (28 days after supplement administration) and declined by the end of the study in all three experimental groups of rabbits. These same animals showed no noticeable differences in the plasma concentrations of total cholesterol or in the high-density lipoprotein cholesterol subfractions. Plasma low-density/very-low-density lipoprotein cholesterol levels remained unchanged at 2 hours after burn injury/sham treatment but increased by the end of the study in all three experimental groups of rabbits. The mean platelet number was significantly higher in burned/sham treated rabbits given soybean oil supplement as compared with numbers in those given either soybean oil + MaxEPA oil or MaxEPA oil supplement. Plasma relative viscosity was highest in the soybean oil-supplemented rabbits, decreased in animals fed soybean oil + MaxEPA, and lowest in MaxEPA oil-supplemented rabbits. Mean bleeding time was lowest in soybean oil-fed rabbits. The bleeding time was higher in rabbits fed soybean oil+MaxEPA oil and highest in MaxEPA oil-supplemented animals. Platelet number and plasma viscosity were highest in the soybean oil-supplemented rabbits and lowest in the MaxEPA oil-supplemented group. The reverse pattern occurred when bleeding time was established. Overall results obtained suggest that supplementation with oils rich in omega-3 and omega-6 fatty acids may have significant effects on the cardiovascular health of burned male New Zealand white rabbits.

Effects of simvastatin on plasma lipoprotein subfractions, cholesterol esterification rate, and cholesteryl ester transfer protein in type II hyperlipoproteinemia

We investigated the effects of simvastatin on plasma levels of lipoprotein subfractions, cholesterol esterification rates and activities of cholesteryl ester transfer protein in 28 patients with type II hyperlipoproteinemia (i.e., nonfamilial hyperlipoproteinemia type IIa and type IIb, and heterozygous familial hypercholesterolemia (FH)). Plasma levels of VLDL-cholesterol (C) and VLDL-triglyceride (TG) were significantly reduced overall by 12.9 ± 58.0% (mean ± S.D.; P < 0.05) and 4.2 ± 54.2% ( P < 0.05) respectively, but not in FH. Plasma levels of IDL-C and IDLT-G were decreased overall by 23.2 ± 47.5% ( P < 0.001) and 12.3 ± 49.7% ( P < 0.05), respectively, again mainly due to decreases seen in nonfamilial type II hyperlipoproteinemia. Plasma levels of LDL1 (1.019 < d < 1.045)-C and LDL1-TG were significantly reduced by 33.1 ± 12.9% ( P < 0.001) and 23.3 ± 24.7% ( P < 0.001), respectively. Plasma levels of LDL2 (1.045 < d < 1.063)-C were significantly reduced by 22.9 ± 18.1% ( P < 0.001) overall but not in FH. Gradient PAGE showed no consistant changes in the distribution of LDL particles. Thus, plasma levels of all apo B-containing lipoprotein subfractions were reduced by simvastatin, but its effects varied among the three subgroups. Cholesterol esterification rates were suppressed by 9.3 ± 19.7% ( P < 0.01) and activities of cholesteryl ester transfer protein were reduced by 30.6 ± 21.5% ( P < 0.001). Changes in CETP activity and in plasma levels of cholesterol in lipoprotein subfractions were not correlated. Thus, the changes in distribution of lipoprotein subfractions were not due mainly to CETP suppression.

Associations of lipoprotein cholesterols, apolipoproteins A-I and B, and triglycerides with carotid atherosclerosis and coronary heart disease. The Atherosclerosis Risk in Communities (ARIC) Study.

Previous research shows generally greater proportional elevation in apolipoprotein B (apoB) levels than in low-density lipoprotein cholesterol (LDL-C) in coronary heart disease (CHD) case subjects compared with control subjects. The Atherosclerosis Risk in Communities study provided general populations of 7261 men and women free of cardiovascular symptoms for evaluating the associations between intima-media thickening in extracranial carotid arteries measured using ultrasound imaging and fasting plasma LDL-C, high-density lipoprotein cholesterol (HDL-C), apoB, apolipoprotein A-I (apoA-I), triglycerides, and HDL density subfractions. A CHD group was selected for comparison. Lipid factors show approximately linear associations with carotid thickness: positive for LDL-C and plasma apoB and negative for HDL-C and apoA-I levels. Apolipoproteins and HDL density subfractions did not contribute to the association after accounting for LDL-C and HDL-C. Compared with control subjects, persons whose carotid thickness exceeded 0.9 mm had greater proportional elevations in LDL-C than in apoB, whereas HDL-C reductions were small. CHD case subjects showed greater proportional elevations of apoB than LDL-C. Although the lipid profiles associated with asymptomatic carotid wall thickening and stenotic coronary disease are similar, the differences found suggest that LDL-C is the most important lipid factor in earlier stages of atherogenesis, whereas the metabolism of triglyceride-rich lipoproteins and its effects on LDL and HDL may be more relevant to later atherothrombotic processes.

High density lipoprotein cholesterol subfractions in older people.

High density lipoprotein (HDL) may be an important risk factor for cardiovascular disease in older people. HDL is heterogeneous with several subfractions. This article describes the distribution and correlates of HDL2 cholesterol (C) and HDL3-C in older people. HDL subfraction cholesterols were measured in 1,127 females and 825 males > or = 65 years old who participated in the Cardiovascular Health Study. Distributions of HDL subfraction cholesterols and bivariate and multivariate relationships were determined in cross-sectional analyses. Mean (+/- SD) concentrations of HDL subfractions were: HDL3-C (M .98 +/- .25, F 1.2 +/- .29 mmol/l), HDL2-C (M .09 +/- .08, F .13 +/- .09 mmol/l). HDL2-C, but not HDL3-C, was slightly higher with age. Using multivariate analysis, both HDL2-C and HDL3-C (in females) were inversely correlated with triglyceride, body weight, and fasting insulin; HDL3-C was inversely correlated with central fat distribution in women. Both HDL2-C and HDL3-C were lower in participants with prevalent cardiovascular disease. However, only HDL3-C was significantly inversely related to carotid stenosis, as measured by ultrasound. The slight increase in HDL-C with age appears to be due to an increase in the HDL2-C subfraction. HDL-C subfractions are independently related to triglyceride levels, body weight, and insulin concentrations in older people, all potentially modifiable risk factors. Both HDL2-C and HDL3-C are lower in older people with prevalent cardiovascular disease, although only HDL3-C was correlated with carotid atherosclerosis. These findings are consistent with the hypothesis that HDL subfractions are important risk factors for atherosclerotic cardiovascular disease in the elderly.

Determinants of insulin sensitivity and consequences for lipoproteins and blood pressure in subjects with non-insulin-dependent diabetes mellitus

The aim of the present study was to investigate the possible determinants of insulin sensitivity and the relationships of these determinants and insulin sensitivity to lipoprotein levels and blood pressure in patients with non-insulin-dependent diabetes mellitus (NIDDM). We studied 46 patients with NIDDM (26 women, 20 men) treated either with diet alone or in combination with sulfonylureas. Insulin sensitivity was assessed as the insulin-mediated glucose uptake rate (M value) with the hyperinsulinemic euglycemic clamp technique. In a multiple regression model, only percent body fat, waist to hip ratio (WHR), and resting energy expenditure (REE) emerged as significant independent determinants of the M value, with a multiple R 2 for the model of 44%, whereas age, hemoglobin A 1c (HbA 1c) level, thyroid function, fitness level, smoking status, alcohol consumption, and dietary habits did not contribute significantly. The M value was independently and negatively associated with the concentrations of triglyceride (TG) and very-low-density lipoprotein (VLDL) cholesterol and positively associated with high-density lipoprotein (HDL) cholesterol subfractions and apolipoprotein A1. In our predominantly normotensive subjects, we found no association between the M value and blood pressure. Moreover, fasting insulin contributed directly, ie, independent of the M value, to the variation of TG, but not to the other lipoproteins and not to blood pressure. The results suggest that in NIDDM (1) insulin sensitivity is determined mainly by percentage body fat and REE, (2) the insulin level determines the TG level directly, whereas the lipoproteins are influenced indirectly as a reflection of the degree of insulin resistance, and (3) insulin sensitivity is not related to blood pressure in a normotensive population.

Regulation of plasma HDL cholesterol and subfraction distribution by genetic and environmental factors. Associations between the TaqI B RFLP in the CETP gene and smoking and obesity.

This study investigated in a healthy population (n = 220) the association of the TaqI B restriction fragment length polymorphism (RFLP) in the cholesteryl ester transfer protein (CETP) gene with plasma high-density lipoprotein (HDL) cholesterol concentration and subfraction distribution. A raised HDL cholesterol level was found in B2B2 homozygotes (B2 cutting site absent) and was associated specifically with a 45% increase in HDL2 compared with B1B1 homozygotes (B1B1, 77 +/- 39 mg/100 mL, mean +/- SD; B2B2, 112 +/- 59 mg/100 mL; P < 0.01). Total plasma, very-low-density lipoprotein, and HDL triglyceride levels did not differ among the genotype groups, nor did plasma apolipoprotein AI levels (B1B1, 1.45 +/- 0.35 mg/mL, mean +/- SD; B2B2, 1.56 +/- 0.33 mg/mL). Thus, the genetic variation appeared to be independent of metabolic factors that are known to regulate HDL levels. Plasma CETP exchange activity was unlikely to be the cause of the association, since it did not differ between genotype groups and was not correlated with HDL2 concentration. Multivariate analysis demonstrated that the TaqI B polymorphism had an effect on HDL cholesterol and HDL2 that was independent of age, sex, body mass index, oral contraceptive use, exercise, alcohol consumption, and plasma triglycerides. In smokers, the presence of the B2B2 genotype did not result in increased HDL cholesterol or HDL2, whereas in obese subjects, the difference between B1B1 and B2B2 individuals was diminished. We conclude that the TaqI B RFLP is associated with a quantitatively significant effect on plasma HDL2 levels that is independent of plasma triglycerides and interacts with lifestyle factors.

Relation between Lifestyle Factors and High-Density Lipoprotein Cholesterol Subfraction Levels among Healthy Adults Living in a Rural District.

Serum levels of total high-density lipoprotein cholesterol (HDL-C) and its subfractions (HDL2-Cand HDL3-C) were measured in 227 healthy Japanese adults. These values were related to a number of lifestyle factors.On co-variance analysis, alcohol drinking had an independent contribution to HDL-C and HDL3-C (p<0.05) in males. Cigarette smoking showed no association with subfractions of HDL-C in males. Three physical activities-sport, work and leisure time activity-had no significant association with subfractions of HDL-C. The degree of obesity as expressed by body mass index (BMI) was significantly negatively related (p<0.05) to HDL-C and HDL2-C levels among females. Among males, although a trend test showed no statistically significant relation to BMI, HDL-C and HDL2-C levels were significantly higher (p<0.05) in the normal group (20≤BMI<25) than in the obese group (BMI≥25).

Coronary Heart Disease Risk Factors in Relation to the Menopause

The incidence of coronary heart disease increases after the menopause, but the mechanism is unclear. We assessed the relationship of age to fasting plasma insulin, total triglycerides, total cholesterol, total high density lipoprotein (HDL) cholesterol, including HDL2 and HDL3 subfractions, total/HDL cholesterol ratio, body mass index and waist-hip circumference ratio in 394 women and 824 men aged 40-69 years who participated in an epidemiological survey in East Bristol. Women over the age of 50 years were assumed to be post-menopausal, this being the median age of the menopause in Britain. Compared to younger women, post-menopausal women had higher plasma triglycerides by 0.31 mmol/l (95 per cent confidence interval 0.10-0.43), higher cholesterol by 1.0 mmol/l (0.77-1.24), higher total/HDL cholesterol ratio by 0.42 (0.15-0.69), higher insulin by 2.0 mU/l (0.02-0.11), higher body mass index by 0.9 kg/m2 (0.02-1.68), and higher waist-hip ratio by 0.02 (0.01-0.03). Age-related changes in men were absent or less marked. On multiple regression analysis the increases in plasma total triglycerides, total cholesterol, high density lipoprotein cholesterol, HDL3 cholesterol and total/HDL cholesterol ratio in postmenopausal women were independent of body mass index, waist-hip ratio, cigarette habits, alcohol consumption and antihypertensive therapy. On analysis of covariance sex had a significant effect on all variables which was independent of age. We conclude that there is an increase in coronary heart disease risk factors in women as they pass through the menopause, and insulin may play a central role.

Determinants of total high density lipoprotein cholesterol and high density lipoprotein subfraction levels among hispanic and non-hispanic white persons with normal glucose tolerance: The San Luis Valley diabetes study

Determinants of total high-density lipoprotein cholesterol (HDL-C) and HDL subfractions were assessed in Hispanic and non-Hispanic white persons ( n = 932), aged 20–74 years, in the San Luis Valley, Colorado. Using multiple regression, BMI was negatively associated with HDL-C, HDL 2-C, and HDL 3-C in men and HDL-C and HDL 3-C in women. Among females, current smokers had lower HDL-C and subfractions. Women on beta-blockers had lower HDL 3-C levels. For both sexes, a positive association was observed between age and HDL-C and subfractions and physical activity with HDL-C and HDL 3-C. Drinking alcohol (≧ 50 g/week) was associated with higher HDL-C and HDL 3-C in both sexes and HDL 2-C in women. The positive association of age and negative associations of the subscapular/triceps ratio and fasting insulin had consistent relationships with HDL-C, HDL 2-C, and HDL 3-C in men and women. Ethnicity was not significantly associated with HDL-C or subfractions after controlling for body fat distribution or fasting insulin.

An interaction between the human cholesteryl ester transfer protein (CETP) and apolipoprotein A-I genes in transgenic mice results in a profound CETP-mediated depression of high density lipoprotein cholesterol levels.

We have previously described two transgenic mouse lines, one heterozygous for the human apo A-I gene and the other heterozygous for a human cholesteryl ester transfer protein (CETP) minigene driven by the mouse metallothionein-I gene promoter. In the current study, these two lines were crossed producing control, HuCETPTg, HuAITg, and HuAICETPTg mice to study the influence of CETP on HDL cholesterol levels, particle size distribution, and metabolism in animals with mouse and human-like HDL. In the HuCETPTg and HuAICETPTg animals, zinc induction approximately doubled plasma CETP activity, with no activity in plasma from the control and HuAITg animals. The only significant effect of CETP on lipoprotein subfraction cholesterol concentrations was for HDL-C. Compared to control animals, HuCETPTg animals had lower HDL-C, 20% before and 35% after Zn induction, and compared to HuAITg animals, HuAICETPTg animals had lower HDL-C, 35% before and 66% after Zn induction. Control and HuCETPTg HDL consist primarily of a single size population with a mean diameter of 10.00 +/- 0.10 nm and 9.71 +/- 0.05 nm, respectively. HuAITg HDL consists primarily of three distinct HDL size subpopulations with peak diameters of 10.35 +/- 0.08 nm, 8.80 +/- 0.06 nm, 7.40 +/- 0.10 nm, and HuAICETPTg HDL also consists primarily of three distinct HDL size subpopulations with peak diameters of 9.87 +/- 0.05 nm, 8.60 +/- 0.10 nm, 7.30 +/- 0.15 nm before, and 9.71 +/- 0.08 nm, 8.50 +/- 0.11 nm, 7.27 +/- 0.15 nm after zinc induction, respectively. Western blotting analysis of nondenaturing gradient gels of plasma with a monoclonal antibody to CETP indicated that in HuCETPTg and HuAICETPTg mice, 22 and 100%, respectively, of the CETP was HDL associated. Turnover studies with HDL doubly labeled with 125I apo A-I and 3H cholesteryl linoleate indicated that the CETP-induced fall in HDL-C was associated with increased HDL-cholesterol ester fractional catabolic rate in both the absence and presence of human apo A-I, suggesting CETP-mediated transfer of HDL-cholesterol ester to apo B-containing lipoproteins. In summary, these studies suggest that CETP has a much more profound effect on HDL cholesterol levels in transgenic animals expressing human apo A-I. This may be due to an enhanced interaction of CETP with human compared to mouse apo A-I or to the HDL particles they produce.

Effects of Nifedipine GITS and Atenolol Monotherapy on Serum Lipids, Blood Pressure, Heart Rate, and Weight in Mild to Moderate Hypertension

Forty-nine patients, with ages ranging from eighteen to seventy years and with mild to moderate primary hypertension (sitting diastolic blood pressure of greater than or equal to 95 mmgH and less than or equal to 115 mmHg) were randomized into a twenty-one-week, double-blind, prospective study to determine the effects of monotherapy of nifedipine GITS (gastrointestinal therapeutic system) versus atenolol on serum lipids, lipid subfractions, apolipoproteins, (apo), and blood pressure (BP). Nifedipine GITS and atenolol significantly reduced blood pressure, but nifedipine GITS reduced sitting and standing systolic BP significantly more than atenolol (p = .001). Sitting and standing heart rate decreased significantly (p = 0.001) during atenolol therapy but did not change significantly during nifedipine GITS therapy. Atenolol increased weight (mean change + 2.2 lb; p = 0.011), but nifedipine GITS decreased weight (mean change - 2.4 lb; p = 0.07). Nifedipine GITS had a more favorable effect on the lipid profile. High density lipoprotein cholesterol (HDL-C) and HDL2 subfractions were increased significantly (p = .001) as were apo A1 (p = 0.037) and apo A2 (p = 0.025). Nifedipine GITS increased HDL3 (NS), reduced triglycerides (TG) (NS), and had no significant effect on total cholesterol (TC) low density lipoprotein cholesterol (LDL-C) and apo B. Atenolol significantly increased serum total cholesterol (p = 0.039) and HDL-C and HDL2 (p = 0.049 and 0.048 respectively). Atenolol increased TG (NS) and apo B (NS) with little change in apo A1 and apo A2. It is concluded that nifedipine GITS had equal or better antihypertensive efficacy than atenolol and had a more favorable effect on the lipid profile. These effects may offer advantages in reducing CHD risk.

Serum Copper and the Risk of Acute Myocardial Infarction: A Prospective Population Study in Men in Eastern Finland

The authors investigated the association of serum copper concentration with the risk of acute myocardial infarction in 1,666 randomly selected men aged 42, 48, 54, or 60 years who had no symptomatic ischemic heart disease at entry. Baseline examinations in the Kuopio Ischaemic Heart Disease Risk Factor Study in Eastern Finland were done during 1984 to 1988. In Cox multivariate survival models adjusting for age, examination year, ischemic electrocardiogram in exercise, maximal oxygen uptake, diabetes, family history of ischemic heart disease, cigarette-years, mean systolic blood pressure, serum high density lipoprotein (HDL) cholesterol subfraction HDL2 and low density lipoprotein (LDL) cholesterol concentrations and blood leukocyte count, serum copper concentration in the two highest tertiles (1.02-1.16 mg/liter and 1.17 mg/liter or more) associated with 3.5-fold (95% confidence interval (Cl) 1.3-9.4, p less than 0.05) and 4.0-fold (95 percent Cl 1.5-10.8, p less than 0.01) risk of acute myocardial infarction. These data indicate that high copper status, reflected by elevated serum copper concentration, is an independent risk factor for ischemic heart disease.

The role of insulin and body fat in associations of physical activity with lipids and lipoproteins in a biethnic population. The San Luis Valley Diabetes Study.

It has been postulated that the positive effects of physical activity on high density lipoprotein cholesterol (HDL-C) and HDL-C subfraction 2 (HDL-C2) are mediated through insulin action because increased activity lowers insulin levels and lower insulin levels are associated with higher HDL-C. These relations were evaluated in a rural population of Hispanic and non-Hispanic white (NHW) adults in Colorado. Included were 138 men and 152 women with normal glucose tolerance confirmed by World Health Organization criteria. Total physical activity was assessed by 7-day recall interviews. No significant associations were observed among women. Among men, activity was inversely associated with fasting insulin (r = -0.17, p less than 0.05). From analysis of covariance models including the interaction term activity x ethnicity, total HDL-C was 43.4 mg/dl (95% confidence interval [CI] = 39.1, 47.7) in the low tertile of activity and 50.4 mg/dl (95% CI = 46.3, 54.5) in the high tertile for NHW men, after adjustment for fasting insulin, fasting glucose, body mass index (BMI), waist to hip ratio (WHR), and age. For Hispanic men, adjusted HDL-C was 43.4 mg/dl (95% CI = 38.6, 48.2) and 49.1 mg/dl (95% CI = 44.0, 54.2) in the low and high tertiles, respectively. Adjusted HDL-C2 levels were 52% higher in the most compared with the least active NHW men, whereas there was no difference by activity for Hispanic men. Higher adjusted mean levels of HDL-C3 were observed for the high compared with the low activity tertile in both ethnic groups. Ethnicity-specific models showed that for NHW men, activity explained 12% (p = 0.01), fasting insulin explained 5% (p = 0.05), and BMI explained 6% (p = 0.04) of the variability in total HDL-C, after adjustment for fasting glucose, WHR, and age. These models confirmed that effects of insulin and body fat did not explain the observed associations between activity and total HDL-C and its subfractions.

Obesity in Hispanic Americans

The prevalence of obesity among Hispanic American populations is generally greater than among white populations in the United States. Among Mexican Americans, the prevalence of obesity was higher than among either Cuban Americans or Puerto Ricans. It is well known that the prevalence of diabetes increases with increasing levels of obesity or body mass index. However, it does not appear that the high prevalence of obesity in Mexican Americans completely accounts for the higher prevalence of diabetes seen in this ethnic group. Among Mexican Americans, the association of selected cardiovascular disease risk factors, high-density lipoprotein cholesterol subfractions and systolic blood pressure, was similar to that seen among other U.S. populations. Individuals with diabetes had higher values than seen among those without diabetes. In a comparison of nutrient intake in two Mexican-American populations, one rural and one urban, there were no major differences other than higher calorie intakes in the rural population compared with the urban population. In addition, the diet in the rural population, based on higher levels of the Keys score, was more atherogenic than that of the urban population.

Age and dietary polyunsaturated fat alter high density lipoprotein subfraction cholesterol concentrations in a pediatric population of African green monkeys.

African green monkeys were raised from birth to 60 months of age on diets containing cholesterol (0.8 mg/kcal) and enriched in polyunsaturated (polyunsaturated to saturated fat ratio [P:S] = 2.5) or saturated (P:S = 0.3) fat. Lipoproteins were isolated from plasma of a group of animals (N = 123) and were separated by gel filtration chromatography at 9, 14, 26, 38, and 50 months of age, which covered a period through adolescence into young adulthood. Total plasma cholesterol (TPC) concentrations were 16% lower (p = 0.01) in the polyunsaturated fat-fed group, and high density lipoprotein (HDL) cholesterol concentrations averaged 20% lower (p = 0.008) in this group between 14 and 50 months of age, while plasma apolipoprotein A-I (apo A-I) averaged 7% lower (p = 0.06) over this age interval in the animals. The HDL cholesterol to apo A-I ratio was found to be significantly lower (p = 0.006) in the animals fed the polyunsaturated fat diet. This suggested that the HDL subfraction distribution might differ between groups. In a subset of animals (n = 105, 64 male and 41 female), HDL was subfractionated by density gradient ultracentrifugation into six subfractions, HDL-I to HDL-VI, from lowest to highest density. The saturated fat-fed animals had significantly higher cholesterol concentrations in HDL-I and significantly lower cholesterol concentrations in HDL-III, HDL-IV, and HDL-V. These effects held across all ages studied; therefore, these diet effects were not age dependent. In both diet groups, the HDL subfraction pattern changed with age such that the HDL-I and HDL-II cholesterol concentrations decreased, and those of HDL-IV, HDL-V, and HDL-VI increased as the animals matured. The decrease in HDL-I with age appeared to result primarily from a decrease in HDL-I in males, while the HDL-I cholesterol concentration in females did not change with age. We conclude that diet, age, and gender all affect HDL subfraction distribution and therefore can potentially modify the relative atherogenicity of the plasma HDL populations. It remains for future studies to demonstrate the effectiveness of each subfraction in promoting or preventing the cholesterol deposition of atherosclerosis.

Effect of cigarette smoking on serum lipid, lipoprotein and apolipoprotein levels in hypertensives receiving β-adrenoreceptor blocking drugs

Both cigarette smoking and propranolol administration significantly alter plasma lipid profile. We examined the relationship of cigarette smoking and propranolol administration with fasting serum total cholesterol, triglyceride, lipoprotein cholesterol subfractions (high density, low density, and very low density), Apo-A, Apo-B and ratios obtained from these variables in 42 hypertensive patients. Significantly lower values of HDL cholesterol, Apo-A and HDL-C/total cholesterol and Apo-A/Apo-B ratios were observed in smokers taking propranolol than non-smokers not taking propranolol. Smokers who were not on propranolol also had significantly lower values as compared to non-smokers. These findings suggest that smoking may be the more significant factor responsible for alteration in lipid profile.

Apolipoproteins and High-density Lipoprotein Subfraction Cholesterol in Insulin-treated IDDM Children

Apolipoproteins and High-density Lipoprotein Subfraction Cholesterol in Insulin-treated IDDM Children

The Effects of Polyunsaturated Fat vs Monounsaturated Fat on Plasma Lipoproteins: The Power of a Study-Reply

In Reply.— On our study of diet and high-density lipoprotein cholesterol subfractions, Dr Passey has focused on the negative low-density lipoprotein (LDL) cholesterol results. We designed our study with β error equal to .20 specifically to detect differences in highdensity lipoprotein cholesterol and cholesterol subfractions. We obtained significant differences for these variables and therefore think that the study groups were of sufficient size to report these positive results appropriately. While change in LDL cholesterol was not part of our primary hypothesis, clearly LDL cholesterol has a greater SE and greater differences would be needed with this sample size to obtain significance. With 80% power we could detect significance with an LDL cholesterol difference of 0.28 mmol/L, below which are levels we consider clinically insignificant. We consider the nonsignificant change in LDL cholesterol of 0.10 mmol/L to be of little clinical significance. We faithfully pointed out not only our P value but