Subclinical atherosclerosis as a target of therapy: potential role of statins

Psychological, social and biological determinants of ill health (pSoBid): study protocol of a population-based study

BACKGROUND

Disadvantaged communities suffer higher levels of physical and mental ill health than more advantaged communities. The purpose of the present study was to examine the psychosocial, behavioural and biological determinants of ill health within population groups in Glasgow that differed in socioeconomic status and in their propensity to develop chronic disease especially coronary heart disease and Type 2 diabetes mellitus.

METHODS

Participants were selected at random from areas known to be at the extremes of the socioeconomic continuum in Glasgow. Within the categories of least deprived and most deprived, recruitment was stratified by sex and age to achieve an overall sample containing approximately equal numbers of males and females and an even distribution across the age categories 35-44, 45-54 and 55-64 years. Individuals were invited by letter to attend for assessment of their medical history, risk factor status, cognitive function and psychological profile, morbidity, and carotid intima-media thickness and plaque count as indices of atherosclerosis. Anonymised data on study subjects were collected from the General Practice Administration System for Scotland to analyse characteristics of participants and non-participants.

RESULTS

700 subjects were recruited. The response (active participants per 100 invitation letters) in the least deprived group was 35.1% and in the most deprived group was 20.3%. Lowest response was seen in young males (least deprived 22.4% and most deprived 14.1%).

CONCLUSION

This cross-sectional study recruited the planned sample of subjects from least deprived and most deprived areas within Glasgow. As evident in other studies response differed between the most and least deprived areas. This study brought together researchers/academics from diverse disciplines to build a more sophisticated understanding of the determinants of health inequalities than can be achieved through unidisciplinary approaches. Future analyses will enable an understanding of the relationships between the different types of measure, and of the pathways that link poverty, biology, behaviour and psychology and lead to health inequalities.

Development of a lipoprotein based molecular imaging MR contrast agent for the noninvasive detection of early atherosclerotic disease

INTRODUCTION

Currently there are no clinically available means of noninvasively detecting early atherosclerotic disease because these lesions are characterized by an accumulation of extracellular lipid and foam cells, but a lack of significant wall thickening or architectural distortion.

OBJECTIVE

We hypothesize that a paramagnetically labeled low density lipoprotein (LDL) could serve as a functional probe to detect sites of abnormal lipid metabolism in the vessel wall that represent sites of early disease.

METHODS

Isolated LDL was first incubated with manganese-mesoporphyrin, a hydrophobic MR contrast agent (MnMeso). Size exclusion chromatography and absorption mass spectroscopy were performed on the resulting samples to prove that an association between the two occurred. Subsequently, foam cell cultures (n=7) were incubated (10-30 microg/ml for 48 h) with these labeled lipoproteins and the T1 relaxivity of centrifuged pellets of these cells was determined by using an inversion recovery sequence on a 1.5T scanner. These results were compared to control measurements made from foam cell cultures fed unlabeled lipoproteins (n=7).

RESULTS

Measured T1 relaxation times of the cells fed the MnMeso-LDL (443.3 +/- 51.8 ms) was significantly different from the T1 relaxivity obtained from cells fed unlabeled lipoproteins (661.3 +/- 60.9 ms). These findings indicate that the amount of contrast bound to the constructed lipoproteins is sufficient to produce measurable MR signal changes noninvasively.

CONCLUSIONS

The study results support the feasibility of future in vivo MR experiments with labeled lipoproteins to assess lipoprotein kinetics in the vessel wall, which will hopefully provide a means of detecting early atherosclerotic disease.

Management of hyperlipidemia in the pediatric population

Heterozygous familial hypercholesterolemia (FH) affects one in every 500 persons and is the most common cause of markedly elevated cholesterol levels in children. Other causes of primary hyperlipidemia include familial combined hyperlipidemia, which is also common (approximately 1%) but not usually manifest until after puberty, and very rare genetic disorders that may lead to severe hypertriglyceridemia and chylomicronemia syndrome. In children with heterozygous FH, the short-term risk of clinical events is low; therefore, management starts with stratification of risk, followed by dietary modification, and in high-risk cases, pharmacologic treatment initiated after puberty. Male gender, a family history of premature coronary heart disease, and level of low-density lipoprotein (LDL) cholesterol above 4.9 mmol/L are important determinants of risk. Trials have shown that statins effectively lower LDL cholesterol levels; in one study, statins restored endothelial function, with no clinically adverse effects. The effects of statins for longer than 2 years have not been studied. The use of bile acid sequestrants (resins) is limited by compliance and side effects. Children with homozygous FH require expert management with LDL apheresis, high doses of effective statins, and cardiologic follow-up. Ezetimibe, the first in a new class of cholesterol absorption inhibitors, may provide additional efficacy in homozygous FH.