Low-density lipoprotein subclass distribution pattern and adiposity-associated dyslipidemia in postmenopausal women

Small Dense Low Density Lipoprotein Cholesterol, Paraoxonase 1 and Lipid Profile in Postmenopausal Women: Quality or Quantity?

BACKGROUND AND AIMS

Atherosclerosis, the root cause of cardiovascular disease (CVD), has a number of risk factors-some modifiable and some not. CVD increases in women particularly during the postmenopausal period. Small dense low-density lipoprotein (sdLDL), a subclass of LDL, is an important determinant of atherosclerosis in postmenopausal women. Paraoxonase1 (PON1) is a high-density lipoprotein (HDL)-associated enzyme that prevents oxidative modifications in LDL and HDL. With this background, we studied the sdLDL-C, PON1 and lipid profile in postmenopausal women to compare between quality and quantity of LDL.

METHODS

We studied 80 pre- and postmenopausal women (40/group). The following parameters were studied: lipid profile, sdLDL-C and PON1 levels. With proper statistical tools the correlation between these parameters was studied.

RESULTS

Postmenopausal women, in comparison with premenopausal women, have significantly increased levels of serum triglycerides and sdLDL-C and very-low-density lipoprotein cholesterol (VLDL-C) and significantly decreased levels of HDL-C and PON1. PON1 activity was negatively correlated with age, TC, TG, LDL-C and sdLDL-C (r = -0.574, -0.119, -0.226, -0.473 and -0.455, respectively) and positively correlated with HDL-C (r = 0.368), whereas sdLDL-C was positively correlated with age, TC, TG, LDL-C (r = 0.633, 0.485, 0.561 and 0.705, respectively) and negatively with HDL-C (r = -0.235). Stepwise multiple regression analysis demonstrated HDL-C and menopausal status as the best determinant for PON1 (R(2) = 0.320, p < 0.05) and menopausal status, LDL-C, TG, and TC were the best determinants for sdLDL-C (R(2) = 0.606, p < 0.05).

CONCLUSION

The results of the present study suggest quality, i.e., sdLDL-C, is more important than only LDL-C levels. Similarly, decrease in PON1 and increase in sdLDL-C go hand in hand. This shows that antioxidant capacity is compromised with a qualitative downfall in lipoproteins in postmenopausal women.

Low density lipoprotein bionanoparticles: From cholesterol transport to delivery of anti-cancer drugs

In this review article, we highlight the importance of low-density lipoprotein (LDL) and its implications in the field of drug delivery to cancer cells. LDL is naturally occurring bionanoparticles (BNP) with a size of 18–25 nm. These BNPs specifically transport cholesterol to cells expressing the LDL receptors (LDLRs). Several tumors overexpress LDLRs, presumably to provide cholesterol for sustaining a high rate of membrane synthesis. LDL BNPs are biocompatible and biodegradable, favorably bind hydrophobic and amphiphilic drugs, are taken up by a receptor-mediated mechanism, have a half-life of 2–4 days, and can be rerouted. Drugs can be loaded onto LDL BNPs by surface loading, core loading, and apoprotein interaction. LDL may be used as a drug carrier for treatment of atherosclerosis, cancer, and in photodynamic therapies.

Diets containing barley significantly reduce lipids in mildly hypercholesterolemic men and women

BACKGROUND

Barley has high amounts of soluble fiber but is not extensively consumed in the US diet.

OBJECTIVE

This study investigated whether consumption of barley would reduce cardiovascular disease risk factors comparably with that of other sources of soluble fiber.

DESIGN

Mildly hypercholesterolemic subjects (9 postmenopausal women, 9 premenopausal women, and 7 men) consumed controlled American Heart Association Step 1 diets for 17 wk. After a 2-wk adaptation period, whole-grain foods containing 0, 3, or 6 g beta-glucan/d from barley were included in the Step 1 diet menus. Diets were consumed for 5 wk each and were fed in a Latin-square design. Fasting blood samples were collected twice weekly.

RESULTS

Total cholesterol was significantly lower when the diet contained 3 or 6 g beta-glucan/d from barley than when it contained no beta-glucan; the greatest change occurred in the men and postmenopausal women. HDL and triacylglycerol concentrations did not differ with the 3 amounts of dietary beta-glucan. Large LDL and small VLDL fractions and mean LDL particle size significantly decreased when whole grains were incorporated into the 3 diets. Large LDL and large and intermediate HDL fractions were significantly higher, mean LDL particle size was significantly greater, and intermediate VLDL fractions were significantly lower in the postmenopausal women than in the other 2 groups. A group-by-diet interaction effect was observed on LDL fractions and small LDL particle size.

CONCLUSION

The addition of barley to a healthy diet may be effective in lowering total and LDL cholesterol in both men and women.

Relationship of adiposity to the population distribution of plasma triglyceride concentrations in vigorously active men and women

Although it is known that triglyceride concentrations increase with adiposity, whether the same increase applies for different percentiles of the triglyceride distribution has not been reported. Therefore, physician-supplied triglyceride concentrations from 7288 male and 2326 female runners were divided into strata according to the body mass index (BMI) and circumferences of the waist, hip and chest. The percentiles of the triglyceride distribution within each stratum were used to determine the cross-sectional regression slope between adiposity and triglyceride levels at each triglyceride percentile. Compared to the 5th percentile of the triglyceride distribution, the rise in men's triglycerides at the 95th percentile per unit of adiposity was 14-fold greater for BMI, 7.8-fold greater for waist circumference, 3.6-fold greater for hip circumference, and 4.4-fold greater for chest circumference. The rise in women's triglyceride concentrations at the 95th percentile was 8-fold greater than at the 5th percentile for each kg/m(2) increase in BMI. These results suggest that the metabolic effects of adiposity on plasma triglycerides depend upon whether the concentrations are high or low. This contradicts statistical assumptions upon which prior studies of adiposity have based their analyses. We speculate that the reported greater increases in triglycerides per unit of adiposity in whites than blacks, in men than women, and in low-density lipoprotein (LDL) pattern B than A are all consistent with the relationships we observe. It remains to be verified whether these relationship also apply to less active populations.

The lipid and clinical effects of sequential transdermal estradiol and estradiol/norethisterone acetate in 674 women

OBJECTIVE

To measure lipid changes induced by patches delivering continuous estradiol (E(2)) and sequential norethisterone acetate (NETA) in a large population of symptomatic menopausal women, compared with a non-symptomatic control group.

PATIENTS AND METHODS

A total of 748 women recruited in 42 different hospital services and clinics in Spain were invited to participate in a prospective, open, controlled study for 48 weeks. Six hundred and seventy-four women were evaluated in the treatment group, and 74 in the control group. Treatment consisted of patches delivering 0.05 mg/day E(2) for the first 14 days of the cycle, and 0.05 mg/day E(2) plus 0.25 mg/day NETA for another 14 days.

RESULTS

Use of patches led to a slight, but significant decrease of 1.3% and 0.9% in concentrations of total cholesterol and low-density lipoprotein cholesterol (LDL-C), respectively. A substantial 37.0% decrease in triglycerides concentration was observed in treated women. The treatment effectively reduced climacteric symptoms (Kupperman index) for the duration of the study. Compliance was acceptable, with 489 (72.6%) women completing the study. Adverse events were reported by 137 (20.3%) women.

CONCLUSIONS

Transdermal administration of E(2) and sequential NETA for a period of 48 weeks (twelve 28-day cycles) was associated with beneficial changes, albeit of differing magnitudes, in the concentration of total cholesterol, LDL-C and triglycerides. This protective lipid profile, together with satisfactory clinical efficacy and acceptable safety and compliance, makes this system a good alternative in hormone replacement therapy.