Lipids and atherosclerosis

Potential of novel drug delivery strategies for the treatment of hyperlipidemia

Emergence of hyperlipidemia in urban population of India and the world at large is very high and accounts to several fatal diseases. This condition is known to manifest elevated levels of lipids and/or lipoproteins. Serious limitations like inadequate solubility, less absorption, less bioavailability, ineffectiveness in lowering of cholesterol levels, patient incompliance and so on are noticed with majority of anti-hyperlipidemic drugs and dosage forms, which are used conventionally. To overcome these shortcomings, building technology platforms for development of appropriate dosage forms is the need of the hour. These efforts are required to maximize patient acceptability while maintaining safety, efficacy, accessibility and affordability. Hyperlipidemia, its types, etiology, pathophysiology and conventional dosage forms are discussed here. The current approaches and novel developments which illustrate controlled drug release and sustained therapeutic effect along with site specific and target oriented drug delivery with better patient compliance are also reviewed critically. Despite the incentives provided by the efforts of formulation scientists, there is still a need for implementation of pharmaceutical technologies that enable to combat limitations of anti-hyperlipidemic drugs and conventional dosage forms associated with it. The present review emphasize on applications of novel drug delivery systems in pharmacotherapy of anti-hyperlipidemic drugs demonstrating the advantages and disadvantages.

Effects of soya oligosaccharides and soya oligopeptides on lipid metabolism in hyperlipidaemic rats

In the present study, we aimed to examine the effects of soya oligosaccharides (SOS) and soya oligopeptides (SOP) on blood lipid levels, release of vasoactive substances, antioxidant activity and faecal bile acid (FBA) excretion in rats fed a high-fat diet (HFD). Male Sprague-Dawley rats were evenly divided into five groups according to diets as follows: regular diet (control), HFD, HFD enriched with 2 % of SOS (SOS), HFD enriched with 3 % of SOP (SOP) and HFD enriched with 2 % SOS and 3 % SOP (SOSP). The results showed that SOS and SOP significantly reduced plasma total cholesterol, LDL-cholesterol and TAG, whereas HDL-cholesterol concentration was significantly increased. Furthermore, SOS and SOP reduced plasma apoB, apoE and the apoB:apoAI ratio, whereas apoAI was significantly increased. Moreover, SOS and SOP also reduced plasma thromboxane A₂ (TXA₂) and the TXA₂:prostacyclin (PGI₂) ratio, whereas plasma PGI₂ and nitric oxide were significantly increased. In addition, SOS and SOP significantly reduced serum and liver malondialdehyde concentrations and increased FBA excretion. However, we did not observe obvious influences of SOS and SOP on superoxide dismutase activities in the liver of HFD-fed rats. The combination of 2 % SOS and 3 % SOP showed a more marked effect than SOS or SOP alone in improving the lipid profile, release of vasoactive substances and increasing FBA excretion (P < 0.05). In summary, SOS and SOP might help prevent atherosclerosis through improving abnormal blood lipid levels, regulating vasoactive substances and protecting against oxidative stress.

Effects of Fufang Zhenzhu Tiaozhi Prescription (), A Chinese herbal preparation, on atherosclerosis in ApoE-/- mice and related mechanisms

OBJECTIVE: The present study was designed to observe the effects and the possible mechanisms of Fufang Zhenzhu Tiaozhi Prescription (, FZT), a Chinese herbal preparation, on atherosclerosis in apolipoprotein E deficient (ApoE-/-) mice. METHODS: ApoE-/- mice were randomized to groups orally administrated without or with FZT (4.5 and 9 g crude drug/kg body weight, respectively). Atherosclerotic plaques, lipids profifiles in serum, aortic cholesterol content, serum indices of oxidative stress were measured, and mRNA expressions of scavenger receptors CD36 and scavenger receptor-A (SR-A) in aorta were analyzed. RESULTS: FZT dose-dependently suppressed the atherosclerotic plaques and reduced the cholesterol contents in aorta (P<0.05, P<0.01). In addition, FZT decreased the levels of total cholesterol and triglyceride in serum (P<0.05, P<0.01), inhibited the production of oxidized low density lipoprotein and malonaldehyde, and increased the superoxide dismutase activity in serum (P<0.05 or P<0.01). Furthermore, FZT down-regulated the mRNA expressions of CD36 and SR-A in the aorta (P<0.05, P<0.01). CONCLUSIONS: FZT reduced the atherosclerotic formation in ApoE-/- mice. The mechanisms might be related to the decrease of serum lipid level, the improvement of oxidative stress and the down-regulated expressions of scavenger receptors CD36 and SR-A, consequently reducing the foam cell formation, the hallmark of early atherosclerosis.

Continued inhibition of atherosclerotic lesion development in long term Western diet fed CD36o /apoEo mice

We previously determined that absence of CD36 inhibited atherosclerosis lesion development in 12-week Western diet fed apoE degrees mice, and this was due largely to absence of macrophage CD36. It is possible that at later stages of disease this effect would be lost due to the progressive nature of lesion development and involvement of other factors. However, lesion development continues to be characterized by recruitment of macrophages and foam cell formation, thus it is also possible that delay in lipid accumulation as a result of absence of CD36 would continue to retard lesion development. The objective of this study was to determine if absence of CD36 continued to inhibit lesion formation. Background matched apoE degrees and CD36 degrees /apoE degrees mice were fed a Western diet for up to 35 weeks. At 20 and 35 weeks, lesion area was 25 and 35% less, respectively, in CD36 degrees /apoE degrees mice. Most impressive was the difference in gross appearance of the aortas at 35 weeks: apoE degrees aortas were sclerotic and nearly occluded by lesion, whereas aortas from CD36 degrees /apoE degrees mice had smaller lesions that were more punctate. We conclude that absence of CD36 continues to reduce lesion burden even at late stages of disease in the apoE degrees model.

Mapping of microsatellite loci and association of aorta atherosclerosis with LG VI markers in the rabbit

Twenty-three rabbit microsatellites were extracted from the EMBL nucleotide database. Nine of these markers, together with nine earlier published microsatellite markers, were found to be polymorphic between the AX/JU and IIIVO/JU inbred strains. By using an F(2) intercross we could integrate five markers into the rabbit linkage map. One anonymous microsatellite marker could be assigned to chromosome 1, and one microsatellite marker, located within the metallothionein-1 gene, could be added to linkage group VI (LG VI). Three microsatellite markers (one anonymous, one located within the PMP2 gene, and one located within the FABP6 gene) constitute a new linkage group (LG XI). We also measured the degree of dietary cholesterol-induced aorta atherosclerosis in the F(2) animals. A significant cosegregation was found between the degree of aorta atherosclerosis and the allelic variation of the biochemical marker Est-2 on LG VI in male rabbits. This association was not found in female rabbits.

Gene-gene interaction in the RAS system in the predisposition to myocardial infarction in elder population of St. Petersburg (Russia)

The aim of this study was to estimate the frequencies of some DNA polymorphisms of two genes of the renin-angiotensin system (RAS), M235T angiotensinogen gene and insertion-deletion polymorphism in angiotensin-converting enzyme gene, in older (>55 years old) myocardial infarction survival and control groups. For this purpose 198 myocardial infarction (MI) patients and 152 randomly selected healthy persons have been analyzed. We have not found any differences in allele and genotype distribution in the above-mentioned genes for either group. However, statistical research showed a significant increase of double homozygotes IITT in the group of MI patients as compared with those in the control group. In this respect we suggested that gene-gene interaction in the RAS system may be considered to be a predisposing factor for MI development.

Vascular disease and lipids in diabetes

Atherosclerosis kills more patients with diabetes than all other causes combined. Aggressive reversal and treatment of dyslipidemias is the only proven prevention for coronary events in the patient with type 2 diabetes. Glycemic control with diet, oral hypoglycemic agents, and insulin, when necessary, is often only partially effective in normalizing lipid values in type 2 diabetes. Intensive treatment with lipid-regulating agents, particularly HMG-CoA reductase inhibitors, is often necessary to normalize diabetes-associated dyslipidemias. HMG-CoA reductase inhibitors are also the only agents thus far shown in prospective multicenter trials to reduce the risk of coronary events in diabetic patients.

Diabetes and Atherosclerosis: Mechanisms and Management

OBJECTIVE

To discuss the association of diabetes and atherosclerosis and outline various management options.

METHODS

We reviewed the findings in pertinent studies in the literature.

RESULTS

Atherosclerosis accounts for virtually 80% of all diabetes-related mortality. It is also a principal reason for hospitalization of patients with diabetes. Diabetes profoundly affects the pathogenesis of atherosclerosis through various mechanisms. Established cardiovascular risk factors are more prevalent in diabetic than in nondiabetic patients. Although trials of intensive glycemic control have been somewhat disappointing for decreasing atherogenesis, the results of trials with lipid-regulating therapies have been more encouraging.

CONCLUSION

Atherogenesis is a multifactorial, multi-stepped process. Although established risk factors do not entirely explain the increased risk of cardiovascular disease in patients with diabetes, they do seem to have a major role. Therefore, the management of patients with diabetes must address these contributing risk factors.