Lipoproteins, atherogenicity, age and risk of myocardial infarction

Alpha-asarone inhibits HMG-CoA reductase, lowers serum LDL-cholesterol levels and reduces biliary CSI in hypercholesterolemic rats

Our results showed that alpha-asarone was an inhibitor of hepatic HMG-CoA reductase and that the administration of alpha-asarone at 80 mg/kg body wt. for 8 days decreased serum cholesterol by 38% (p < 0.001) in hypercholesterolemic rats. This alpha-asarone treatment affected mainly the serum LDL-cholesterol levels, leaving serum HDL-cholesterol lipoproteins unaffected, with a consequent decrease of 74% in the LDL/HDL ratio. In addition, alpha-asarone especially stimulated bile flow in hypercholesterolemic rats (60%), increasing the secretion of bile salts, phospholipids and bile cholesterol. The drug also reduced the cholesterol levels of gallbladder bile, whereas the concentration of phospholipids and bile salts increased only slightly, leading to a decrease in the cholesterol saturation index (CSI) of bile in the hypercholesterolemic rats. This CSI decrease and the increase in bile flow induced by alpha-asarone may account for the cholelitholytic effect of alpha-asarone. It seems that alpha-asarone induced clearance of cholesterol from the bloodstream and that the excess of hepatic cholesterol provided by LDL-cholesterol is diverted to bile sterol secretion via a bile choleresis process. The inhibition of HMG-CoA reductase and the increase in bile flow induced by alpha-asarone, as well as the decrease in the CSI, could then explain the hypocholesterolemic and cholelitholytic effects of alpha-asarone.

Peripheral arterial disease--epidemiological aspects

As many as 10 million people in the USA have peripheral arterial disease (PAD) with a prevalence over 10% in people aged more than 60 years old. Generally, men have a higher prevalence of PAD than women. The risk factors for PAD are similar to those for coronary artery disease (CAD) and cerebrovascular disease (CBVD), but diabetes and cigarette smoking have a particularly strong association with PAD. Patients with PAD also have CAD and CBVD as co-morbidities, although the extent of co-morbidity depends on the sensitivity of assessment. The risk of mortality is proportional to the severity of PAD, and the relative risk of all-cause mortality due to PAD is unaltered by the presence of CAD or CBVD. PAD is under-recognized and under-treated, even though it should be regarded as a severe disease leading to significant death and disability from stroke and myocardial infarction (MI). Thus, accurate diagnosis of PAD could provide an early indication of the need for intervention and help prevent future morbidity and mortality.

Lipoproteins, diabeto-genicity, age and risk of diabetes mellitus death

OBJECTIVE

To examine the clinical significance of a specific relationship between very low density lipoprotein (VLDL) and high density lipoprotein (HDL), namely their differential, in relation to Type 2 non-insulin dependent diabetes mellitus (NIDDM).

METHODS

The study subjects were 300 female and 300 male patients of doctors in city and rural New South Wales referred for lipid studies. Their clinical notes suggested a relationship of VLDL-HDL to diabetes mellitus (DM) and it was therefore hypothesised that this expression is a functional measure of diabeto-genicity.

RESULTS

By incorporation of age, a calculated measure of risk of overt DM and consequent death can be derived. This is confirmed by comparing the age incidence of this risk function with the age incidence of death attributed to DM in the Australian population to give a simple linear correlation. The principal conclusion is drawn from a mathematical model of the population incidence of DM in terms of VLDL, HDL and age.

CONCLUSION

From this model springs the inference that NIDDM is a cumulative dyslipidaemia-over-time process. If this inference is correct, NIDDM can properly be viewed as a societal disease of which all run a measurable risk that increases with age and from which all will die in the long term who do not die sooner from another cause.

IMPLICATIONS

The implications for public health are the ability to identify the individuals at raised risk before DM becomes symptomatic by lipoprotein screening, and the ability to lower risk of DM over the whole population by preventive measures with increased longevity for all.