Lipoprotein Particles In Women Research Articles

Impact of hormonal contraception and weight loss on high-density lipoprotein cholesterol efflux and lipoprotein particles in women with polycystic ovary syndrome.

To study the effects of oral contraceptive pills (OCP), the first-line treatment for PCOS, on high-density lipoprotein cholesterol (HDL-C) function (reverse cholesterol efflux capacity) and lipoprotein particles measured using nuclear magnetic resonance spectroscopy in obese women. Secondary analysis of a randomized controlled trial (OWL-PCOS) of OCP or Lifestyle (intensive Lifestyle modification) or Combined (OCP + Lifestyle) treatment groups for 16 weeks. Eighty-seven overweight/obese women with PCOS at two academic centres. Change in HDL-C efflux capacity and lipoprotein particles. High-density lipoprotein cholesterol efflux capacity increased significantly at 16 weeks in the OCP group [0·11; 95% confidence interval (CI) 0·03, 0·18, P = 0·008] but not in the Lifestyle (P = 0·39) or Combined group (P = 0·18). After adjusting for HDL-C and TG levels, there was significant mean change in efflux in the Combined group (0·09; 95% CI 0·01, 0·15; P = 0·01). Change in HDL-C efflux correlated inversely with change in serum testosterone (rs = -0·21; P = 0·05). In contrast, OCP use induced an atherogenic low-density lipoprotein cholesterol (LDL-C) profile with increase in small (P = 0·006) and large LDL-particles (P = 0·002). Change in small LDL-particles correlated with change in serum testosterone (rs = -0·31, P = 0·009) and insulin sensitivity index (ISI; rs = -0·31, P = 0·02). Both Lifestyle and Combined groups did not show significant changes in the atherogenic LDL particles. Oral contraceptive pills use is associated with improved HDL-C function and a concomitant atherogenic LDL-C profile. Combination of a Lifestyle program with OCP use improved HDL-C function and mitigated adverse effects of OCP on lipoproteins. Our study provides evidence for use of OCP in overweight/obese women with PCOS when combined with Lifestyle changes.

Effects of Exercise on Lipoprotein Particles in Women with Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) commonly have insulin resistance. Insulin resistance is associated with marked abnormalities of lipoprotein size and subclass particle concentration. The purpose of this study was to examine the effects of a moderate-intensity exercise program without weight loss on lipoprotein profiles in women with PCOS. Thirty-seven sedentary PCOS women were randomized to either an 8- to 12-wk ramp-up followed by a 12-wk moderate-intensity exercise program (16-24 wk total, approximately 228 min x wk at 40-60% peak V x O2, n = 21) or control (no change in lifestyle, n = 16). PCOS was defined as <or=8 menses per year and hyperandrogenism (biochemical or clinical with Ferriman-Gallwey score >or=8). Fasting lipoprotein profiles were obtained before and after the intervention. Nuclear magnetic resonance spectroscopy was used to quantify the following: average particle size, total and subclass concentrations of HDL, LDL, and VLDL particles, and calculated HDL cholesterol, triglycerides, and VLDL triglycerides. Wilcoxon exact rank sums tests were used to compare changes in these parameters in the exercise group relative to controls. Twenty women (8 exercisers, 12 controls) completed the study. Comparing exercisers to controls, significant changes were seen in concentrations of the following lipoprotein parameters that are associated with decreased insulin resistance: decreased large VLDL (P = 0.007), calculated triglycerides (P = 0.003), VLDL triglycerides (P = 0.003), and medium/small HDL (P = 0.031) and increased large HDL (P = 0.002) and average HDL size (P = 0.001). In this trial, moderate-intensity exercise without significant weight loss improved several components of the lipoprotein profiles of women with PCOS. These findings support the beneficial role of moderate exercise in this high-risk population.

Effect of type 2 diabetes on various electrophoretic characteristics of low-density lipoprotein particles in women

Coronary heart disease represents the leading cause of death in type 2 diabetic patients. As the small, dense LDL phenotype is a typical feature of the dyslipidaemic state found in type 2 diabetes, this characteristic could be an important mediator of the elevated coronary heart disease risk in this condition. We have therefore studied the effect of type 2 diabetes on various electrophoretic characteristics of LDL particles. Potential differences in LDL peak particle size and in concentration of LDL cholesterol in small (<255 A) and large (>260 A) LDL particles were assessed by polyacrylamide gradient gel electrophoresis among 183 non-diabetic and 56 type 2 diabetic women. LDL peak particle size was significantly smaller in type 2 diabetic women than in non-diabetic women (p<0.0001). In addition, the proportion of small LDL particles (<255 A) was higher in type 2 diabetic women, whereas the proportion of large LDL particles (>260 A) was lower than in non-diabetic women (p<0.0002). Type 2 diabetic women also had the highest waist circumference and triglyceride levels (p<0.03). When subgroups of non-diabetic and type 2 diabetic women were individually matched (n=41) for similar waist circumference and triglyceride levels, the differences initially found in LDL peak particle size and in the proportion of small and large LDL particles remained significantly different between the two groups (p<0.01). These results provide evidence that type 2 diabetes may have an independent effect on LDL peak particle size and on the proportion of small and large LDL particles.

Lipolytic Enzyme Effect on Small Low-Density Lipoprotein Particles in Women Treated With Estrogen

Lipolytic Enzyme Effect on Small Low-Density Lipoprotein Particles in Women Treated With Estrogen

Lipolytic enzyme effect on small low-density lipoprotein particles in women treated with estrogen

Objective: To test whether hydrolysis of low-density lipoprotein (LDL) triglyceride by lipolytic enzymes decreases the size of LDL particles in women treated with estrogen replacement. Methods: Fifteen postmenopausal women received 0.625 mg conjugated equine estrogens daily for 3 months. Plasma concentrations of total cholesterol, triglyceride, and high-density lipoprotein (HDL) cholesterol were measured before and after therapy. We also assayed levels of total, free, and esterified cholesterol, triglyceride, and protein in LDL. Plasma samples were incubated at 37C for 24 hours and LDL fractions were isolated by ultracentrifugation. After LDL samples were further incubated with or without lipoprotein lipase (500, 700, and 1000 ng/mL) at 37C for 24 hours, LDL triglyceride, LDL protein, and the diameter of LDL particles were measured. Results: Estrogen decreased total cholesterol and increased triglyceride and HDL cholesterol in plasma. Estrogen treatment decreased the ratio of cholesteryl ester/protein, whereas the ratio of triglyceride/protein increased. Estrogen decreased LDL particle diameter. Incubation of plasma increased the ratio of LDL triglyceride/protein from 0.40 ± 0.14 to 0.48 ± 0.15 ( P < .05) and decreased the ratio of LDL cholesteryl ester/protein from 1.17 ± 0.25 to 1.09 ± 0.22 ( P < .05), but LDL particle diameter did not change. Incubation of LDL with lipoprotein lipase reduced the LDL triglyceride/protein ratio, and decreased the diameter of LDL particles from 25.61 ± 0.87 nm to 24.89 ± 0.88 nm (500 ng/mL, P < .05), 24.62 ± 1.20 nm (700 ng/mL, P < .05), and 24.67 ± 1.19 nm (1000 ng/mL, P < .05). Conclusion: In women treated with estrogen, hydrolysis of triglyceride in LDL particles might be accompanied by reduced particle size.

Plasma lipoprotein particle concentrations in postmenopausal women with unstable coronary artery disease. Analysis of diagnostic accuracy using receiver operating characteristics.

The contribution of plasma lipids to cardiovascular risk is usually evaluated by measuring plasma concentrations of total cholesterol, triglycerides and HDL cholesterol, and calculating LDL cholesterol concentration. We investigated plasma concentrations of apolipoproteins and lipoprotein particles in women with unstable coronary artery disease (CAD) to evaluate whether these, better than the routine lipid status, could differentiate women with and without coronary atherosclerosis. Blood samples for lipid analyses were collected from 119 angiographically examined postmenopausal 49-79-year-old women with unstable CAD, and from 101 age-matched controls. Mean plasma concentrations were compared and the discriminatory ability of the different variables were tested using receiver operating characteristics (ROC). At coronary angiography 19% had normal vessels and 81% had coronary atherosclerosis. A disturbed triglyceride metabolism was the most pronounced lipid abnormality in women with unstable CAD and coronary atherosclerosis. ROC showed that none of the evaluated variables had a particularly high discriminatory power regarding unstable CAD or coronary atherosclerosis. The ratio cholesterol/HDL cholesterol was best with an ROC area of 0.79. Furthermore, the newer lipid variables, i.e. lipoprotein particles and apolipoproteins, were no better than the traditional variables. Lipoprotein changes reflecting a disturbed triglyceride metabolism are most pronounced in women with unstable CAD and coronary atherosclerosis. Lipoprotein particles and apolipoproteins alone were no better than lipids and lipoproteins in separating women with from those without coronary atherosclerosis. Our study does not support the measurement of apolipoproteins and lipoprotein particles on the basis of diagnostic accuracy alone.

Small Low-Density Lipoprotein Particles in Women With Natural or Surgically Induced Menopause

Small Low-Density Lipoprotein Particles in Women With Natural or Surgically Induced Menopause

Small low-density lipoprotein particles in women with natural or surgically induced menopause

Objective: To investigate the mechanism of the decrease in the size of low-density lipoprotein (LDL) particles in women with natural menopause and women with surgically induced menopause. Methods: We measured plasma levels of total cholesterol; triglycerides; high-density lipoprotein (HDL) cholesterol; apolipoproteins A-I, A-II, and B; and sex hormones in 45 women; 15 women were premenopausal, 15 were naturally postmenopausal, and 15 were surgically menopausal. Lipoprotein lipase and hepatic triglyceride lipase activities were measured in postheparin plasma. Concentrations of total cholesterol and of apolipoprotein B in LDL also were measured. Low-density lipoprotein particle diameter was determined by gradient gel electrophoresis. Results: Plasma levels of total cholesterol, triglycerides, apolipoprotein B, LDL-total cholesterol, LDL-apolipoprotein B, and the activity of postheparin plasma lipoprotein lipase were significantly higher and concentrations of estrone and estradiol were significantly lower in the naturally postmenopausal and surgically menopausal women than in the premenopausal women. Plasma levels of HDL cholesterol and apolipoproteins A-I and A-II and postheparin plasma hepatic triglyceride activity did not differ significantly between groups. The diameter of LDL particles was significantly reduced in the naturally (25.29 ± 0.19 nm) and surgically (25.29 ± 0.22 nm) menopausal women compared with the premenopausal women (25.88 ± 0.22 nm). Plasma triglyceride levels were negatively correlated with LDL particle diameter in all three groups (premenopausal group: r = −0.64, P < .01; naturally postmenopausal group: r = −0.62, P < .01; and surgically menopausal group: r = −0.76, P < .001). The prevalence of LDL subclass pattern B was significantly increased in the naturally (67%, P < .05) and surgically (60%, P < .05) menopausal women. Conclusion: The plasma concentration of LDL particles was increased after menopause, whether natural or surgically induced. An increase in plasma triglyceride levels in women with low levels of endogenous estrogen appeared to cause the size of LDL particles to be reduced.