Hypercholesterolemia and Dyslipidemia: Issues for the Clinician

Comparative study of cardio-protective effects of zinc oxide nanoparticles and zinc sulfate in streptozotocin-induced diabetic rats

The cardio-protective effects of zinc oxide nanoparticles (Zn NPs) against diabetes-induced cardiopathy were evaluated and compared with zinc sulfate (ZnSO₄). A total of 120 Wistar rats were randomly categorized as healthy and diabetic groups. Then, the 2 groups were classified in 5 subgroups. The animals received oral supplementations containing different Zn NP (ie, doses of 1, 3, and 10mg/kg) and ZnSO₄ (30mg/kg) concentrations over 8 weeks. Blood and cardiac tissue samples were collected in the different time intervals and subjected to biochemical and histopathological analysis. Zn NPs showed dual effects, as its middle dose played protective role and recovered cardiac damages evidenced by significant reduction of serum cholesterol, HDL-cholesterol, lipoprotein (a), atherogenic index, TNF-α, cardiac MDA, B-type natriuretic peptide and caspase-3 activity. Apoptosis indices and histopathological features also were improved. However, the highest dose was found to be toxic and resulted in aggravation of the injuries. Another interesting finding is the ability of the higher doses of Zn-NPs (3 and 10mg/kg) to elevate cardiac zinc levels above the normal range in healthy animal. ZnSO₄ also helped to recuperation of the damages, but the middle dose of Zn NPs was more efficient as compared to ZnSO₄. Conclusively, Zn NPs have the potential for Zn delivery in diabetic patients.

Panax notoginseng saponins attenuate atherogenesis accelerated by zymosan in rabbits

Panax notoginseng saponins (PNS) are highly valued traditional Chinese medicine. The effects of PNS (120 mg/kg, once daily administrated intragastrically (i.g.)) on atherosclerosis induced by a high-cholesterol diet and chronic inflammation, which was derived through zymosan (10 mg/kg, once every 2 d) administration intraperitoneally, were evaluated in rabbits for 8 weeks. A normal group, a simple high-fat diet group, and a zymosan plus high-cholesterol diet group (Zym) were used as controls. Typical pathologic changes associated with atherosclerosis in rabbits following induction by zymosan were alleviated by PNS treatment. After 2, 4, 6, and 8 weeks of treatment, PNS decreased the serum levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, interleukin-6 and C-reactive protein as well as increased high-density lipoprotein cholesterol level significantly in comparison with those in the Zym group, except for triglycerides at week 2. In addition, PNS treatment significantly decreased the mRNA expression levels of monocyte chemoattactant protein-1 and nuclear factor-kappaB/p65 in the aorta wall after 8 weeks of treatment compared with the Zym group. In conclusion, PNS attenuates atherogenesis through an antiinflammatory action and regulation of the blood lipid profile.

Is it LDL particle size or number that correlates with risk for cardiovascular disease?

The role of low-density lipoprotein cholesterol (LDL-C) in the pathogenesis of cardiovascular disease (CVD) and the clinical benefit of lowering LDL-C in high-risk patients is well established. What remains controversial is whether we are using the best measure(s) of LDL characteristics to identify all individuals who are at CVD risk or if they would benefit from specific therapies. Despite the successful LDL-C reduction trials, substantial numbers of patients continue to have clinical events in the treatment groups. The size of LDL particles and assessment of the number of LDL particles (LDL-Num) have been suggested as a more reliable method of atherogenicity. Each LDL particle has one apoprotein B-100 measure attached; therefore, determination of whole plasma apoprotein B can be considered the best measure of LDL-Num. Because the cholesterol content per LDL particle exhibits large interindividual variation, the information provided by LDL-C and LDL-Num is not equivalent. Individuals with the same level of LDL-C may have higher or lower numbers of LDL particles and, as a result, may differ in terms of absolute CVD risk. LDL particle size and number provide independent measures of atherogenicity and are strong predictors of CVD.

Gemfibrozil reduces small low-density lipoprotein more in normolipemic subjects classified as low-density lipoprotein pattern B compared with pattern A

We tested the hypothesis that gemfibrozil has a differential effect on low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclass distributions and postprandial lipemia that is different in subjects classified as having LDL subclass pattern A or LDL pattern B who do not have a classic lipid disorder. Forty-three normolipemic subjects were randomized to gemfibrozil (1,200 mg/day) or placebo for 12 weeks. Lipids and lipoproteins were determined by enzymatic methods. The mass concentrations of lipoproteins in plasma were determined by analytic ultracentrifugation and included the S(f) intervals: 20 to 400 (very LDL), 12 to 20 (intermediate-density lipoprotein), 0 to 12 (LDL), and HDL(2) mass (F(1.20) 3.5 to 9.0) and HDL(3) mass (F(1.20) 0 to 3.5). Postprandial measurements of triglycerides and lipoprotein(a) were taken after the patients consumed a 500 kcal/M(2) test meal. Treatment with gemfibrozil, compared with placebo, significantly reduced fasting plasma triglycerides (difference from placebo +/- SE; -50.2 +/- 20.6 mg/dl, p = 0.02), total cholesterol (-16.4 +/- 7.5 mg/dl, p = 0.04), apolipoprotein B (-16.1 +/- 5.5 mg/dl, p = 0.006), very LDL mass of S(f) 20 to 400 (-50.8 +/- 24.1 mg/dl, p = 0.02), S(f) 20 to 60 (-17.5 +/- 8.5 mg/dl, p = 0.05), S(f) 60 to 100 (-16.2 +/- 8.1 mg/dl, p = 0.05), and increased peak S(F) (0.48 +/- 0.27 Svedberg, p = 0.08). Gemfibrozil reduced the postprandial triglyceride level significantly at 3 (p = 0.04) and 4 (p = 0.05) hours after the test meal. A significantly different subclass response to gemfibrozil was observed in those with LDL pattern A versus B. Those with LDL pattern B had a significantly greater reduction in the small LDL mass S(f) 0 to 7 (p = 0.04), specifically regions S(f) 0 to 3 (p = 0.009) and S(f) 3 to 5 (p = 0.009). In conclusion, normolipemic subjects with either predominantly dense or buoyant LDL respond differently to gemfibrozil as determined by the changes in LDL subclass distribution. Thus, treatment with gemfibrozil may have additional antiatherogenic effects in those with LDL pattern B by decreasing small dense LDL that is not apparent in those with pattern A.

Differential effect of two nicotinic acid preparations on low-density lipoprotein subclass distribution in patients classified as low-density lipoprotein pattern A, B, or I

We tested the hypothesis that treatment with nicotinic acid results in a differential blood lipid response in subjects classified as having a low-density lipoprotein (LDL) pattern A or B. One hundred eighty hypercholesterolemic subjects were randomized to placebo (n = 61), immediate-release niacin (3,000 mg/day, n = 59), or extended-release niacin (1,500 mg/day, n = 60) for 14 weeks. Lipids and lipoprotein cholesterol were determined with enzymatic methods. LDL subclass distribution was determined with 2% to 16% polyacrylamide gradient gel electrophoresis. Extended- and immediate-release niacin had significant effects on the decrease of triglycerides, total cholesterol, LDL cholesterol, apoprotein B, lipoprotein(a), and apoprotein A-I and significantly increased high-density lipoprotein cholesterol. The 2 nicotinic acid compounds and doses significantly increased mean LDL peak particle diameter and percent distribution in large LDL I and IIa, with a significant decrease in small LDL IIIa, IIIb, and IVb. In patients with LDL pattern B compared with those with pattern A, extended-release niacin (1,500 mg/day) increased LDL peak particle diameter significantly more and decreased the percent distributions of small LDL IIIa, LDL IIIb, and LDL IVa significantly more. With 3,000 mg/day, immediate-release nicotinic acid in patients with LDL pattern B exhibited a significantly greater increase in LDL peak particle diameter and large LDL IIa and IIb and significantly greater decreases in small LDL IIIa, IIIb, and IVa compared with patients with pattern A. These differences in response between patients with LDL pattern A and those with pattern B were not reflected by changes in the standard lipid profile, including apoproteins A-I and B. Nicotinic acid has a significantly different effect on lipids and lipoprotein subclass distribution in subjects classified as having LDL subclass pattern A or B. Nicotinic acid has a significantly greater effect on the decrease of small LDL subclass distribution and increase in LDL peak particle diameter in pattern B versus pattern A.