Basic precepts and the lipid hypothesis of atherogenesis

Structure-apoptotic potency evaluations of novel sterols using human leukemic cells

Three oxidized analogs of cholesterol have been characterized for their ability to cause apoptotic cell death in CEM-C7-14 human leukemic cells. In addition to testing 15-ketocholestenol (K15), 15-ketocholestenol hydroxyethyl ether (CK15), and 7-ketocholesterol hydroxyethyl ether (CK7), an oxysterol of known apoptotic response, 25-hydroxycholesterol (25OHC), served as a standard for comparison. Growth studies based on dye exclusion by viable cells while using a sublethal concentration of oxysterols ranked their potency for cell kill as 25OHC > K15 > CK15 > CK7. Both the TUNEL assay (terminal deoxynucleotidyl transferase-mediated dUTP-X nick end labeling), which quantifies the amount of DNA nicks caused by a toxic agent, and the MTT assay, which measures cell metabolism and thus reflects cell viability, substantiated the same rank order. An ELISA assay for evaluating release of DNA fragments into the cytosol after treatment gave a similar potency order. The oncogene c-myc mRNA was suppressed by all three oxysterols, with 25OHC and K15 being the most potent suppressors. Hoechst and Annexin V staining documented that these oxysterols kill cells by an apoptotic pathway as evidenced by condensation of nuclear chromatin and plasma membrane inversion, respectively. From these in vitro studies, we believe that 25OHC, K15, and possibly CK15 have the potential to be chemotherapeutic agents.

The hypothetical epidemic of coronary heart disease and atherosclerosis

Accurate usage of the term 'epidemic' is important scientifically and it should ideally be used to mean only contagious diseases, not used loosely or emotively to mean non-infectious diseases, particularly coronary heart disease, which is a non-specific complication of many diseases. It should not be used as a surrogate term for atherosclerosis of indefinite severity. An epidemic of atherosclerosis is impossible, there being no variation in prevalence because the disease is ubiquitous. Moreover, vital statistics are too unreliable to determine the existence of an increase or decline in coronary heart disease. A coronary heart disease epidemic could be due to an increase in non-atherosclerotic coronary heart disease or increased severity of atherosclerosis. The former has not been studied and the latter would cause a shift to the left in age distribution and is inconsistent with the fall in 'all cause' and stroke mortality rates whilst coronary heart disease mortality allegedly increased alarmingly. A coronary heart disease epidemic, having no scientific basis, negates any reason for the sustained search for a speculative causative environmental factor.

The questionable wisdom of a low-fat diet and cholesterol reduction

The prevalent wisdom that a low-fat diet and cholesterol reduction are essential to good cardiovascular health is coming under increased scrutiny. An examination of the foundations of this view suggests that in many respects it was ill-conceived from the outset and, with the accumulation of new evidence, it is becoming progressively less tenable. Cross-sectional, longitudinal and cross-cultural investigations have variously suggested that the relationship between dietary fat intake and death from heart disease is positive, negative and random. These data are incompatible with the view that dietary fat intake has any causal role in cardiovascular health. Although hypercholesterolemia is associated with increased liability to death from heart disease, it is as frequently associated with increased overall life expectancy as with decreased life expectancy. These findings are incompatible with labelling hypercholesterolemia an overall health hazard. Moreover, it is questionable if the cardiovascular liability associated with hypercholesterolemia is either causal or reversible. The complex relationships between diet, serum cholesterol, atherosclerosis and mortality and their interactions with genetic and environmental factors suggest that the effects of simple dietary prescriptions are unlikely to be predictable, let alone beneficial. These cautions are borne out by numerous studies which have shown that multifactorial primary intervention to lower cholesterol levels is as likely to increase death from cardiovascular causes as to decrease it. Importantly, the only significant overall effect of cholesterol-lowering intervention that has ever been shown is increased mortality. The stress and helplessness associated with misapprehensions as to the dangers of dietary fat and the asceticism inherent in the war on cholesterol have considerable implications for health practices. Recent research in behavioral immunology suggests that stress and helplessness are likely to compromise immunity and promote ill-health.

The quality of epidemiological data in coronary heart disease and atherosclerosis

There are inherent difficulties in the use of indirect observations in the epidemiology of a chronic ubiquitous disease such as atherosclerosis. Such difficulties do not condone basic errors in epidemiological methodology, the use of low quality data, a lack of precision in measurements, invalid extrapolations and inappropriate use of terminology and coronary heart disease as a surrogate or synonym of coronary atherosclerosis and bias in the interpretation of data. These errors reveal a lack of rigorous and scientific standards in the epidemiology of coronary heart disease. Analysis cannot launder such data. Independent scientists must evaluate the data in respect of precision, logic and truth.

Science, atherosclerosis and the "age of unreason": a review

Research in atherosclerosis has been dominated by the lipid hypothesis. The pathology of both the cholesterol-fed animal and of familial hypercholesterolemia has been misrepresented. The vascular lesions of these disorders are not atherosclerotic but manifestations of fat storage. There has been undue faith in the epidemiology of coronary heart disease and atherosclerosis. Fundamental defects in the epidemiological approach to the cause of atherosclerosis include: (1) misuse of cause and risk factors; (2) misuse of coronary heart disease as an imprecise and inappropriate surrogate endpoint in clinical and mortality studies; (3) use of fallacious monocausal death certificates and mortality rates; (4) assumed causal role of risk factors; (5) use of fallacious dietary data; (6) ecological fallacies; (7) nonspecificity of statistical correlations and selection bias; (8) failure to take note of inconsistencies; (9) inappropriate use of the blood cholesterol level as a surrogate of atherosclerosis (substitution game) without demonstration of any such effect on arteries; and (10) misplaced faith in pathological and experimental corroborative evidence. The epidemiology of atherosclerosis is based on unscientific methodology and the lipid hypothesis as currently envisaged is invalid. There is need to review the cholesterol-lowering campaign especially for normolipidemic subjects.

Another cholesterol hypothesis: cholesterol as antioxidant

Current emphasis on cholesterol as agency if not cause of human atherosclerosis and subsequent cardiovascular disease ignores the essentiality of cholesterol in life processes. Additionally ignored is the ubiquitous presence of low levels of oxidized cholesterol derivatives (oxysterols) in human blood and select tissues, oxysterols also implicated in atherosclerosis. Whereas such oxysterols may be regarded putatively as agents injurious to the aorta, an alternative view of some of them is here proposed: that B-ring oxidized oxysterols of human blood represent past interception of blood and tissue oxidants in vivo by cholesterol as an ordinary aspect of oxygen metabolism. Such interception and subsequent efficient hepatic metabolism of oxysterols so formed, with biliary secretion and fecal excretion, constitute as in vivo antioxidant system. Whether cholesterol, oxysterols, oxidized lipoproteins, or oxidants in blood, singly or in concert, cause or exacerbate human atherosclerosis remains to be understood.

Imprecision of the clinical diagnosis of coronary heart disease in epidemiological studies and atherogenesis

Coronary heart disease (CHD) is an imprecise diagnosis associated with a substantial diagnostic error and provides an erroneous assessment of the morbidity and mortality of myocardial ischemia and of severe coronary atherosclerosis. Due to the inability to measure the severity of atherosclerosis during life, epidemiologists frequently use the incidence of CHD as a surrogate monitor of severe atherosclerosis. It is therefore important in clinical epidemiological studies to appreciate the degree of inaccuracy of CHD statistics, which detracts from the value of such studies and their reliability.