Atherosclerosis in youth

BACKGROUND

Coronary heart disease (CHD) and the related diseases due to atherosclerosis continue to be major public health problems in the industrialized countries and are likely to become serious problems in the developing countries. Treatment of end stage disease has improved, and risk factor modification has succeeded in reducing risk among adults. However, the age at which to begin risk factor control for long-range primary prevention is controversial.

METHODS

A multicenter cooperative study, Pathobiological Determinants of Atheroscle-rosis in Youth (PDAY), was organized in 1985 to examine the relationship of the risk factors for adult CHD to preclinical atherosclerotic lesions in youth. Fourteen participating centers collected arteries, blood, other tissue, and data from 3,000 persons 15-34 years of age who died from external causes and were autopsied in forensic laboratories. Central laboratories evaluated atherosclerosis in the aorta and coronary arteries, measured lipoproteins and thio-cyanate (for smoking) in serum, glycohemo-globin in red blood cells (for blood glucose), thickness of small renal arteries (for hypertension), and body mass index (for obesity). The data were analyzed to determine the progression of atherosclerosis with age in both sexes and the association of the risk factors with atherosclerotic lesions.

RESULTS

Raised lesions of the coronary arteries, the advanced lesions of atherosclerosis that lead directly to CHD, are associated positively with non-HDL cholesterol concentration, hypertension, obesity (in men), and blood glucose concentration; and inversely, with HDL cholesterol concentration. Smoking affects predominantly the abdominal aorta.

CONCLUSIONS

These results suggest that long-range prevention of CHD should begin in adolescence or at least in young adulthood with control of the major established risk factors for adult CHD.

Lipoproteins and atherosclerosis in children: an early marriage?

AIM

Describe the relationship between serum lipoproteins and the development of atherosclerosis in young subjects aged 15-34 years, and discuss the implications for prevention of coronary heart disease.

DATA SYNTHESIS

Data from gross and microscopic evaluation of aorta and coronary arterial specimens as part of the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Study demonstrates that by the age of 15 years, all subjects have atherosclerosis. Lipoprotein risk factors for coronary heart disease are associated with the extent and prevalence of gross aortic and coronary atherosclerosis and with the development of microscopic coronary plaques that have qualities consistent with clinically significant lesions. Association of lipoprotein risk factors with intermediate type atherosclerotic lesions becomes evident in subjects in their late teens, whereas associations with raised lesions become evident in subjects greater than 25 years of age, consistent with a transitional role of intermediate lesion in the formation of advanced plaques.

CONCLUSIONS

Atherosclerosis begins in childhood and a significant number of young people have advanced coronary artery plaques. Early atherosclerosis is accelerated by lipoprotein risk factors. Thus, long-range prevention of atherosclerosis should begin in childhood and should include measures to control hyperlipidemia.

Immunolocalization of apolipoproteins in aortic atherosclerosis in American youths and young adults: findings from the PDAY study

The immunohistochemical distribution of apolipoproteins in the abdominal aortas of 142 men, 15-34 years of age, collected in a cooperative multicenter study group (Pathobiological Determinants of Atherosclerosis in Youth) was examined in relationship to serum VLDL+LDL+HDL cholesterol levels. ApoB deposits were limited to the intima of specimens with intimal fibro cellular thickening or atherosclerotic lesions. Apo A-I, E and J were observed in both the intima and media of the aortas with intimal lesions. The pattern of apoJ distribution was similar to that of apoA-I and E. The distribution patterns of these apolipoproteins in these young adults were very similar to those in adults and old men seen in an earlier study. The extent of apolipoprotein distribution in the intima and media increased with age and the stage of atherosclerosis development, but was not correlated significantly with serum VLDL+LDL or HDL cholesterol levels. The infiltration of lipoprotein particles into the aortic wall seems to be more strongly associated with the progression of intimal lesions rather than with serum cholesterol levels.

Histopathological modifications of early atherosclerotic lesions by risk factors--findings in PDAY subjects

To investigate whether histopathological modifications on early atherosclerotic lesions differ according to risk factors, we compared the histological findings of arteries obtained from a multicenter study in the USA (Pathobiological Determinants of Atherosclerosis in Youth, PDAY) with the antemortem risk factors. The materials comprised aortas and left anterior descending (LAD) coronary arteries of 140 male subjects. Measurements of intimal thickness, classification of intimal lesions, and density of foam cells and intimal fibrosis at the determined sites of LAD and aorta were evaluated. In both arteries, intimal thickness of hypertensives was greater than the normotensives with no definite proliferation of foam cells. In aortas, hypercholesterolemia was associated with an increase in foam cells, but not with an increase in intimal thickness. HDL-C value correlated inversely with number of foam cells in both the arteries, and the degree of intimal thickness in LADs, where early appearance of advanced lesion such as preatheroma and atheroma, was also indicated in the low HDL-C group. Smokers had less number of foam cells in both the arteries and more intensive intimal fibrosis in LAD than non-smokers. Our study suggests that there are several ways to advanced atherosclerotic lesions by risk factors.

Second nation-wide study of atherosclerosis in infants, children and young adults in Japan

This paper reports the results of the second nation-wide cooperative study of atherosclerosis in young Japanese, aged from 1 month to 39 years, who were autopsied between 1991 and 1995. Atherosclerotic lesions in 1066 aortas and 974 coronary arteries were classified into fatty streaks, fibrous plaques and complicated lesions and quantificated with the point-counting method. The results of this study were compared with those of the former study, which was conducted 13 years earlier in almost the same fashion as this study. Atherosclerosis of aorta, which was determined by surface involvement (SI) of atherosclerotic lesions and atherosclerotic index (AI), increased with age in both sexes of the former and the present studies and their tendency for the progression of the extent of atherosclerotic lesions appeared to be similar. In the coronary arteries, the mean values of SI and AI in the males of the present study were greater significantly than those in the male of the former studies and in the female of the both studies in the third and fourth decades. This difference suggests that atherosclerotic lesions are increasing in young Japanese males. It also suggests that these subjects may be increasingly susceptible to atherosclerotic cardiovascular disease with increasing age.

Effects of nonlipid risk factors on atherosclerosis in youth with a favorable lipoprotein profile

BACKGROUND

The strong association between coronary heart disease and dyslipoproteinemia has often overshadowed the effects of the nonlipid risk factors-smoking, hypertension, obesity, and diabetes and impaired glucose tolerance-and even led to questioning the importance of these risk factors in the presence of a favorable lipoprotein profile.

METHODS AND RESULTS

A cooperative multicenter study, the Pathobiological Determinants of Atherosclerosis in Youth (PDAY), examined the relation of the nonlipid risk factors to atherosclerosis in 629 men and 227 women 15 to 34 years of age who died of external causes and who had a favorable lipoprotein profile (non-HDL cholesterol <4.14 mmol/L [<160 mg/dL] and HDL cholesterol >/=0.91 mmol/L [>/=35 mg/dL]). In the abdominal aorta, smokers had more extensive fatty streaks and raised lesions than nonsmokers, and hypertensive blacks had more raised lesions than normotensive blacks. In the right coronary artery, hypertensive blacks had more raised lesions than normotensive blacks, obese men (body mass index >/=30 kg/m(2)) had more extensive fatty streaks and raised lesions than nonobese men, and individuals with impaired glucose intolerance had more extensive fatty streaks. Obese men had more severe lesions (American Heart Association grade 2 through 5) of the left anterior descending coronary artery.

CONCLUSIONS

These substantial effects of the nonlipid risk factors on the extent and severity of coronary and aortic atherosclerosis, even in the presence of a favorable lipoprotein profile, support the need to control all cardiovascular risk factors.

Atherosclerosis and omega-3 fatty acids in the populations of a fishing village and a farming village in Japan

The effect of different dietary habits on atherosclerosis was investigated by examining the content of ordinary diets and relevant risk factors through a mass health survey on two village populations in Japan. In total, 261 inhabitants in the fishing village and 209 in the farming village were examined for body build, blood pressure, and blood chemistry. Information on smoking habits and food consumption was obtained using a semi-quantitative item-frequency questionnaire. Pulse wave velocity of the aorta, intima-media thickness of the carotid artery, and atherosclerotic plaques as obtained by ultrasonography were used as measures of atherosclerosis. All measures of atherosclerosis are lower in the fishing village than in the farming village in both men and women. There is a striking 5-8-fold difference in the number of atherosclerotic plaques (P < 0.0001) between the populations. The observed differences in atherosclerosis parallels differences in dietary habits and differences in the serum essential fatty acids. Evaluation of the omega-3 fatty acids over the combined populations reveals a negative association with the number of plaques in the common carotid while the omega-6 fatty acids shows a weak positive association with plaques.

Origin of atherosclerosis in childhood and adolescence

Atherosclerosis begins in childhood as deposits of cholesterol and its esters, referred to as fatty streaks, in the intima of large muscular arteries. In some persons and at certain arterial sites, more lipid accumulates and is covered by a fibromuscular cap to form a fibrous plaque. Further changes in fibrous plaques render them vulnerable to rupture, an event that precipitates occlusive thrombosis and clinically manifest disease (sudden cardiac death, myocardial infarction, stroke, or peripheral arterial disease). In adults, elevated non-HDL-cholesterol concentrations, low HDL-cholesterol concentrations, hypertension, smoking, diabetes, and obesity are associated with advanced atherosclerotic lesions and increased risk of clinically manifest atherosclerotic disease. Control of these risk factors is the major strategy for preventing atherosclerotic disease. To determine whether these risk factors also are associated with early atherosclerosis in young persons, we examined arteries and tissue from approximately 3000 autopsied persons aged 15-34 y who died of accidental injury, homicide, or suicide. The extent of both fatty streaks and raised lesions (fibrous plaques and other advanced lesions) in the right coronary artery and in the abdominal aorta was associated positively with non-HDL-cholesterol concentration, hypertension, impaired glucose tolerance, and obesity and associated negatively with HDL-cholesterol concentration. Atherosclerosis of the abdominal aorta also was associated positively with smoking. These observations indicate that long-range prevention of atherosclerosis and its sequelae by control of the risk factors for adult coronary artery disease should begin in adolescence and young adulthood.

Associations of coronary heart disease risk factors with the intermediate lesion of atherosclerosis in youth. The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

The raised fatty streak (fatty plaque) is the gross term for the lesion intermediate between the juvenile (flat) fatty streak and the raised lesion of atherosclerosis. We measured the percentage of intimal surface involved with flat fatty streaks, raised fatty streaks, and raised lesions in the aortas and right coronary arteries of 2876 autopsied persons aged 15 through 34 years who died of external causes. Raised fatty streaks were present in the abdominal aortas of approximately 20% of 15- to 19-year-old subjects, and this percentage increased to approximately 40% for 30- to 34-year-old subjects. Raised fatty streaks were present in the right coronary arteries of approximately 10% of 15- to 19-year-old subjects, and this percentage increased to approximately 30% for 30- to 34-year-old subjects. The percent intimal surface involved with raised fatty streaks increased with age in both arteries and was associated with high non-high density lipoprotein (HDL) and low HDL cholesterol concentrations in the abdominal aorta and right coronary artery, with hypertension in the abdominal aorta, with obesity in the right coronary artery of men, and with impaired glucose tolerance in the right coronary artery. Associations of risk factors with raised fatty streaks became evident in subjects in their late teens, whereas associations of risk factors with raised lesions became evident in subjects aged >25 years. These results are consistent with the putative transitional role of raised fatty streaks and show that coronary heart disease risk factors accelerate atherogenesis in the second decade of life. Thus, long-range prevention of atherosclerosis should begin in childhood or adolescence.

Association of Coronary Heart Disease Risk Factors with microscopic qualities of coronary atherosclerosis in youth

BACKGROUND

This study examined whether atherosclerosis in young people is associated with the risk factors for clinical coronary heart disease (CHD). Methods and Results-Histological sections of left anterior descending coronary arteries (LADs) from 760 autopsied 15- to 34-year-old victims of accidents, homicides, and suicides were graded according to the American Heart Association (AHA) system and computerized morphometry. Risk factors (dyslipoproteinemia, smoking, hypertension, obesity, impaired glucose tolerance) were assessed by postmortem measurements. Approximately 2% of 15- to 19-year-old men and 20% of 30- to 34-year-old men had AHA grade 4 or 5 (advanced) lesions. No 15- to 19-year-old women had grade 4 or 5 lesions; 8% of 30- to 34-year-old women had such lesions. Approximately 19% of 30- to 34-year-old men and 8% of 30- to 34-year-old women had atherosclerotic stenosis > or =40% in the LAD. AHA grade 2 or 3 lesions (fatty streaks), grade 4 or 5 lesions, and stenosis > or =40% were associated with non-HDL cholesterol > or =4.14 mmol/L (160 mg/dL). AHA grade 2 or 3 lesions were associated with HDL cholesterol <0.91 mmol/L (35 mg/dL) and smoking. AHA grade 4 or 5 lesions were associated with obesity (body mass index > or =30 kg/m(2)) and hypertension (mean arterial pressure > or =110 mm Hg).

CONCLUSIONS

-Young Americans have a high prevalence of advanced atherosclerotic coronary artery plaques with qualities indicating vulnerability to rupture. Early atherosclerosis is influenced by the risk factors for clinical CHD. Long-range prevention of CHD must begin in adolescence or young adulthood.

Pathobiological determinants of atherosclerosis in youth (PDAY) cardiovascular specimen and data library

In 1985, investigators organized a multi-center study, Pathobiological Determinants of Atherosclerosis in Youth (PDAY), to examine the relationships of cardiovascular risk factors to atherosclerosis involving more than 3,000 young persons 15 through 34 years of age who died of external causes. Reports from the PDAY group confirmed that atherosclerosis begins in the teens and showed that the progression of the lesions is strongly influenced by the same risk factors that predict risk of clinically manifest coronary disease in middle-aged adults. The results emphasize the need for early and aggressive control of all risk factors in young persons for long-range prevention of coronary heart disease and related diseases. Recent funding by the Louisiana Cancer and Lung Trust Fund (LCLTF) has assisted Pathology at Louisiana State University Health Sciences Center (LSUHSC) in the following objectives: (1) maintaining this national research resources; (2) making the unique specimens available to interested investigators; and (3) continuing support for studies at LSUHSC which investigate the effects of smoking on the development of atherosclerotic lesions.

Effects of coronary heart disease risk factors on atherosclerosis of selected regions of the aorta and right coronary artery. PDAY Research Group. Pathobiological Determinants of Atherosclerosis in Youth

We examined topographic distributions of atherosclerosis and their relation to risk factors for adult coronary heart disease in right coronary arteries and abdominal aortas of more than 2000 autopsied persons 15 through 34 years of age. We digitized images of Sudan IV-stained fatty streaks and of manually outlined raised lesions and computed the percent surface area involved by each lesion in each of 6 regions of each artery. In abdominal aortas of 15- to 24-year-old persons, fatty streaks involve an elongated oval area on the dorsolateral intimal surface and another oval area in the middle third of the ventral surface. Raised lesions in 25- to 34-year-old persons involve an oval area in the distal third of the dorsolateral intimal surface. In other areas of the abdominal aortas of older persons, fatty streaks occur but raised lesions are rare. In the right coronary arteries of 15- to 24-year-old persons, fatty streaks are most frequent on the myocardial aspect of the first 2 cm. Raised lesions follow a similar pattern in 25- to 34-year-old persons. High non-HDL cholesterol and low HDL cholesterol concentrations are associated with more extensive fatty streaks and raised lesions in all regions of both arteries. Smoking is associated with more extensive fatty streaks and raised lesions of the abdominal aorta, particularly in the dorsolateral region of the distal third of the abdominal aorta. Hypertension is not associated with fatty streaks in whites or blacks but is associated with more extensive raised lesions in blacks. Risk factor effects on arterial regions that are vulnerable to lesions are approximately 25% greater than risk factor effects assessed over entire arterial segments. These risk factor effects on vulnerable sites emphasize the need for risk factor control during adolescence and young adulthood to prevent or delay the progression of atherosclerosis.

Smoking and atherosclerosis in youth

Coronary heart disease is the most common cause of death in the US. Studies have demonstrated that smoking is a major risk factor for coronary heart disease and that a positive relationship occurs between smoking and aortic and coronary atherosclerosis in adults. In 1985, a multicenter cooperative study, Pathobiological Determinants of Atherosclerosis in Youth (PDAY), was organized to study atherosclerosis in trauma victims 15-34 years of age. Reports from this study have demonstrated that smoking is strongly associated with the prevalence and extent of grossly visible raised lesions in the abdominal aorta but only weakly associated with similar lesions in the right coronary artery. Coronary arteries from 50 smokers and 50 non-smokers were classified microscopically using a system developed by the American Heart Association in order to determine the stage at which smoking affects atherosclerosis. Smokers had over twice as many advanced lesions, types IV and V, as non-smokers (32 vs 14%) and fewer early lesions, types I, II, III, as non-smokers (38 vs 62%). The prevalence of advanced or types IV and V lesions (32%) was over twice that of intermediate or type III lesions (14%) in smokers. The opposite relationship was observed in non-smokers (14 vs 26%). This observation suggest that intermediate lesions progress rapidly into advanced lesions in smokers and that intima formerly having early lesions is replaced by intima with raised lesions.

Lipid and apolipoprotein predictors of atherosclerosis in youth: apolipoprotein concentrations do not materially improve prediction of arterial lesions in PDAY subjects. The PDAY Research Group

We compared serum lipid and apolipoprotein predictors of atherosclerosis in cases from the multicenter study, Pathobiological Determinants of Atherosclerosis in Youth (PDAY). The lipid measures included HDL cholesterol (HDL-C) and non-HDL-C, and the apolipoprotein measures included concentrations of apoA1, apoB, and Lp(a), and sizes of the apo(a) proteins. We tested whether the apolipoprotein measures predicted atherosclerotic lesions as well as the more traditional lipid measures. We estimated extent of lesions as fatty streaks or raised lesions (fibrous plaques, complicated or calcified lesions) in 3 sites: thoracic aorta, abdominal aorta, and right coronary artery. Neither apoA1 nor apoB measures were as strongly or consistently correlated with extent of lesions as the corresponding lipid measure (HDL-C and non-HDL-C, respectively). Beyond the basic model that included sex, age, race, smoking status, hypertension, and the lipid measures, apoA1 and apoB added only an average 1.3% increased explanatory ability to the model, whereas HDL-C plus non-HDL-C added an average 2.5%. The results suggest that the traditional lipid measures are more useful than apolipoprotein measures for detecting young persons at high risk of precocious atherosclerosis. Because of large racial differences, the two Lp(a)-related measures, Lp(a) concentrations and apo(a) size, were evaluated in blacks and whites separately. Under these circumstances, neither of the Lp(a)-related measures was strongly or consistently correlated with extent of lesions.

Prevalence and extent of atherosclerosis in adolescents and young adults: implications for prevention from the Pathobiological Determinants of Atherosclerosis in Youth Study

CONTEXT

Atherosclerosis, the underlying cause of coronary heart disease, has been shown to be present even in young adults.

OBJECTIVE

To document the extent and severity of atherosclerosis in adolescents and young adults in the United States.

DESIGN AND SETTING

The Pathobiological Determinants of Atherosclerosis in Youth Study, a multi-institutional autopsy study conducted in US medical centers. Subjects A total of 2876 study subjects, between 15 and 34 years old, black and white, men and women, who died of external causes and underwent autopsy between June 1, 1987, and August 31, 1994.

MAIN OUTCOME MEASURES

Extent, prevalence, and topography of atherosclerotic lesions.

RESULTS

Intimal lesions appeared in all the aortas and more than half of the right coronary arteries of the youngest age group (15-19 years) and increased in prevalence and extent with age through the oldest age group (30-34 years). Fatty streaks were more extensive in black subjects than in white subjects, but raised lesions did not differ between blacks and whites. Raised lesions in the aortas of women and men were similar, but raised lesions in the right coronary arteries of women were less than those of men. The prevalence of total lesions was lower in the right coronary artery than in the aorta, but the proportion of raised lesions among total lesions was higher in the right coronary artery than in the aorta.

CONCLUSIONS

Atherosclerosis begins in youth. Fatty streaks and clinically significant raised lesions increase rapidly in prevalence and extent during the 15- to 34-year age span. Primary prevention of atherosclerosis, as contrasted with primary prevention of clinically manifest atherosclerotic disease, must begin in childhood or adolescence.

Relation of a postmortem renal index of hypertension to atherosclerosis and coronary artery size in young men and women. Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

In a cooperative multicenter study, the Pathobiological Determinants of Atherosclerosis in Youth, we measured atherosclerosis of the aorta and right coronary artery (RCA) in 2403 black and white men and women 15 through 34 years of age who died of external causes and were autopsied in forensic laboratories. We measured the diameter of the opened, flattened, and fixed RCA and the diameter, intimal thickness, intimal cross-sectional area, medial thickness, and medial cross-sectional area of the pressure-perfused, fixed left anterior descending (LAD) coronary artery. Using the ratio of intimal thickness to outer diameter of the small renal arteries to predict mean arterial pressure during life, we classified the cases as normotensive (mean arterial pressure < 110 mm Hg) or hypertensive (mean arterial pressure > or = 110 mm Hg). The prevalence of hypertension by age, sex, and race corresponded closely with that measured in a survey of the living population. Hypertension had little or no effect on fatty streaks. Hypertension was associated with more extensive raised lesions in the abdominal aortas and RCAs of blacks > 20 years of age and in the RCAs of whites > 25 years of age. At all ages, women had less extensive raised lesions in the RCAs than did men, but the effect of hypertension on raised lesions was similar to that in men. Adjustment for serum lipoprotein cholesterol levels and smoking in a subset of cases yielded results similar to those obtained without adjustment. Hypertension was associated with larger diameters of the RCA and LAD coronary artery and with larger cross-sectional intimal and medial areas of the LAD coronary artery. Hypertension augments atherosclerosis in both men and women primarily by accelerating the conversion of fatty streaks to raised lesions beginning in the third decade of life, and the effect of hypertension increases with age.

Cardiovascular risk factors and hyalinization of renal arterioles at autopsy. The Honolulu Heart Program

Nephrosclerosis, commonly found in subjects with hypertension and diabetes, is marked by hyalinization of arterioles and fibroplasia of small arteries in the renal cortex. Cardiovascular risk factors that predicted subsequent hyalinization of renal arterioles at autopsy were identified, using data from the Honolulu Heart Program, a prospective epidemiological study of cardiovascular disease (CVD) in Japanese-American men. Among 8006 participants at baseline, 1381 died between 1965 and 1982; 285 of these had a protocol autopsy, and 150 had assessments of arteriolar hyalinization from renal tissue. Subjects were categorized into four groups on the basis of the number of hyalinized arterioles per square centimeter of renal tissue, and CVD risk factor levels and proportions were compared across these groups with the use of general linear models and logistic regression. Multivariate assessment using logistic regression demonstrated that diastolic blood pressure (DBP) and glucose level were positively associated and alcohol intake was negatively associated with an elevated degree of renal arteriolar hyalinization, independent of other CVD risk factors. The odds ratios for elevated hyalinization associated with a 10-mm Hg increase in DBP, a 20-mg/dL increase in glucose level, and a 30-mL/d increase in alcohol intake were 1.97 (95% confidence interval [CI] = 1.24-3.12), 1.23 (95% CI = 1.07-1.41), and 0.24 (95% CI = 0.11-0.55), respectively. Associations were similar when prevalent cases of CVD were excluded and when autopsy selection bias was taken into account. Renal arteriolar hyalinization was also more strongly associated with atherosclerosis in the larger cerebral vessels (Spearman's r = .59, P < .001) than in the coronary arteries (r = .16, P = .073) and aorta (r = .24, P = .022). Hyalinization was significantly related to cardiovascular-renal mortality, and this association was accounted for by other CVD risk factors. These findings suggest that blood pressure, glucose level, and alcohol intake are independent predictors of hyalinization in renal arterioles and that this type of renal vasculopathy may be a marker for atherosclerosis in other vascular regions, particularly the cerebral vessels. The protective association involving alcohol and the possibility that renal arteriolar hyalinization may be an indicator of cerebral atherosclerosis may warrant investigation in other populations.

Atherosclerosis in youth: are hypertension and other coronary heart disease risk factors already at work?

The purposes of this review were to describe the natural history of atherosclerosis in youth, discuss the role of adult coronary heart disease (CHD) risk factors in the development of atherosclerosis-particularly in the young- and present the relationship between atherosclerosis and hypertension. Evidence is presented that, by age 15 years, 100% of the youth have aortic atherosclerosis and about one-half have coronary atherosclerosis. Risk factors for adult CHD, including lipoproteins, smoking, glycohemoglobin (a marker for diabetes), obesity, and hypertension, are associated with extent and prevalence of atherosclerosis in young people. Hypertension seems to play its role mainly by converting early atherosclerotic lesions (fatty streaks) to more advanced lesions (raised lesions).

Effects of serum lipoproteins and smoking on atherosclerosis in young men and women. The PDAY Research Group. Pathobiological Determinants of Atherosclerosis in Youth

Atherosclerosis begins in childhood and progresses from fatty streaks to raised lesions in adolescence and young adulthood. A cooperative multicenter study (Pathobiological Determinants of Atherosclerosis in Youth [PDAY]) examined the relation of risk factors for adult coronary heart disease to atherosclerosis in 1079 men and 364 women 15 through 34 years of age, both black and white, who died of external causes and were autopsied in forensic laboratories. We quantitated atherosclerosis of the aorta and right coronary artery as the extent of intimal surface involved by fatty streaks and raised lesions and analyzed postmorterm serum for lipoprotein cholesterol and thiocyanate (as an indicator of smoking). The extent of intimal surface involved with both fatty streaks and raised lesions increased with age in all arterial segments of all sex and race groups. Women had a greater extent of fatty streaks in the abdominal aorta than men, but women and men had about an equal extent of raised lesions. Women and men had a comparable extent of fatty streaks in the right coronary artery, but women had about half the extent of raised lesions. Blacks had a greater extent of fatty streaks than whites, but blacks and whites had a similar extent of raised lesions. VLDL plus LDL cholesterol concentration was associated positively and HDL cholesterol was associated negatively with the extent of fatty streaks and raised lesions in the aorta and right coronary artery. Smoking was associated with more extensive fatty streaks and raised lesions in the abdominal aorta. All three risk factors affected atherosclerosis to about the same degree in both sexes and both races. Primary prevention of atherosclerosis by controlling these adult coronary heart disease risk factors is applicable to young men and women and to young blacks and whites.

Predictors of myocardial lesions in men with minimal coronary atherosclerosis at autopsy. The Honolulu heart program

Some cardiovascular risk factors are associated with clinical coronary heart disease but not with autopsy evidence of coronary atherosclerosis. To determine whether these risk factors might operate through mechanisms other than atherosclerosis, we examined associations between cardiovascular risk factors and subsequent intramural myocardial lesions assessed by protocol autopsy between 1965 and 1984 in 120 Japanese-American men from the Honolulu Heart Program who had minimal coronary atherosclerosis (American Heart Association (AHA) panel score < 3 on scale of 1 to 7). Age-adjusted prevalence of myocardial lesions was related to smoking status (P < 0.01), as well as amount, duration, and pack-years of smoking (P < 0.03). In a multiple logistic model, smoking (20 pack-years) was directly associated and fish intake (> or = 2 times/wk) was inversely associated with myocardial lesions independently of age, cholesterol, systolic blood pressure, body mass index, alcohol, diabetes, total calories, and animal protein intake (odds ratio (OR) = 1.5, 95% confidence intervals (CI) = 1.1 to 2.0 and OR = 0.35, 95% CI = 0.2 to 0.9, respectively). The protective effect of fish intake was most evident among men who did not have hypertension at baseline. Indices of obesity, body fat distribution, and physical activity and levels of triglyceride and alcohol intake were not associated with myocardial lesions. Thus, the adverse effects of smoking and the protective effects of fish consumption may extend to individuals relatively free of coronary atherosclerosis, possibly through hemostatic mechanisms or effects on small intramural arteries.

Renovasculopathies of nephrosclerosis in relation to atherosclerosis at ages 25 to 54 years

Renovasculopathies of hypertension include arteriolar hyalinization and arterial intimal fibroplasia. Atherosclerotic features of coronary arteries and aorta include fatty streaks and raised lesions. Data were obtained from a series of 573 autopsies of black and Caucasian males and females aged 25 to 54 years, who died of violent and natural causes unrelated to atherosclerosis. Analysis showed positive correlations of coronary and aortic raised lesions with arteriolar hyalinization. Arterial intimal fibroplasia correlated positively with raised lesions in the aorta but only weakly and inconsistently in the coronary arteries. The extent of fatty streaks in the coronaries, as in the aorta, did not correlate with either form of renovasculopathy. These results provide evidence that hyalinization of renal arterioles may be a marker for young people who have the most advanced coronary atherosclerosis, and who therefore have an early start upon a course toward coronary heart disease later in life.

Relation of a postmortem renal index of hypertension to atherosclerosis in youth. The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

In a cooperative multicenter study, Pathobiological Determinants of Atherosclerosis in Youth, of 1164 young men 15 through 34 years of age who died of external causes and were autopsied in forensic laboratories, we measured atherosclerosis of the aorta and the right coronary artery. Using the ratio of intimal thickness to outer diameter of the small renal arteries to predict mean arterial pressure (MAP) during life, we classified the cases as either normotensive (MAP < 110 mm Hg) or hypertensive (MAP > or = 110 mm Hg). By this criterion, the prevalence of hypertension in blacks was 16%; in whites, 12%. Hypertension was associated directly with blood level of glycohemoglobin (an indicator of blood glucose concentration) and with body mass index (BMI) but inversely with thickness of the panniculus adiposus. Among hypertensive compared with normotensive cases, the extent of raised lesions (mainly fibrous plaques) was greater in the aortas of 30- to 34-year-old men and in the right coronary arteries of 25- to 34-year-old men. The prevalence of raised lesions involving 5% or more of the intimal surface was twofold greater in the aortas and right coronary arteries of hypertensive men throughout the 15-to-34-year age span of the study cases. The association of hypertension with raised lesions was not accounted for by adjusting for glycohemoglobin level, BMI, or thickness of the panniculus adiposus. Hypertension is associated with accelerated atherosclerosis in youth.

Histologic features of atherosclerosis and hypertension from autopsies of young individuals in a defined geographic population: the Bogalusa Heart Study

Histologic features of arterial intima have been quantified at autopsy by morphometric methods in 66 individuals aged 6-30 years, in whom cardiovascular risk factors had been measured prospectively prior to death. Measures of serum cholesterol were found to correlate significantly with the extent of foam cell infiltration seen in paraffin sections and the intensity of lipid staining in frozen sections of the abdominal and thoracic segments of the aorta. A similar correlation in the coronary arteries was weak and inconsistent. Blood pressure was significantly correlated with foam cells and stainable lipid in the abdominal but not the thoracic segment of the aorta. A similar correlation in the coronary arteries was significant, but only in males, and most consistently in the black males. Intimal thickness of the coronary arteries showed sporadic and weak correlations with blood pressure and lipids; however, a strong and consistent correlation was seen between coronary intimal thickness and hyalinization of renal arterioles. With many statistical tests carried out on a limited data set, some particular details are, no doubt, spuriously significant; however, some persistent patterns are beginning to emerge. The reproducible findings support the concept that prospective measurements of blood pressure and serum lipids are associated with a degree of structural characteristics present in children and young adults. Moreover, the observed structural characteristics, specifically the deposition of lipids in the intima of coronary arteries and aorta, are likely to reflect variations in the rates of progression of atherosclerosis.

Environmental and genetic risk factors in early human atherogenesis: lessons from the PDAY study. Pathobiological Determinants of Atherosclerosis in Youth

A multi-institutional study 'Pathobiological Determinants of Atherosclerosis in Youth' (PDAY) was initiated to document the natural history of atherosclerosis, its relationship to risk factors, and pathobiology of lesion development in young subjects. Pathology laboratories in nine centers collected arteries and tissues from over 2000 persons from 15 through 34 years of age whose deaths were attributed to homicides, accidents, or suicides. Arteries were evaluated for lesions, and risk factors were analyzed in a central laboratory. Post-mortem risk factors included serum lipoproteins, serum thiocyanate (smoking), glycohemoglobin (diabetes), thickness of panniculus adiposus (obesity), small renal artery changes (hypertension) and apoprotein isoforms. This study documents the development of atherosclerosis at an early age. It also shows that the recognized risk factors for coronary heart disease are associated with lesion development in the arteries of these young subjects. The PDAY study has a counterpart in Japan where the development of atherosclerosis has been studied in young subjects. This Japanese study, in a population in which coronary heart disease has not yet become a major epidemic, has findings quite similar to the findings from the PDAY study. Studies of atherosclerosis in both Japan and the USA provide strong justification for reducing risk factors in young persons.

Relation of glycohemoglobin and adiposity to atherosclerosis in youth. Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

In a cooperative multicenter study (Pathobiological Determinants of Atherosclerosis in Youth, PDAY) of 1532 young persons 15 through 34 years of age who died of external causes and were autopsied in medical examiners' laboratories, we quantified atherosclerosis of the aorta and the right coronary artery. We analyzed postmortem blood cells for glycohemoglobin and postmortem serum for lipoprotein cholesterol and thiocyanate (as an indicator for smoking). We measured the thickness of the panniculus adiposus and the body mass index (weight per height squared) as indicators of adiposity. Glycohemoglobin levels exceeding 8% were associated with substantially more extensive fatty streaks and raised lesions in the right coronary artery in persons more than 25 years of age and with more extensive raised lesions in the aorta in persons more than 30 years of age. Both thickness of the panniculus adiposus and body mass index were associated with more extensive fatty streaks and raised lesions in the right coronary artery. The associations of atherosclerotic lesions with glycohemoglobin and adiposity were not explained by a less favorable lipoprotein profile or smoking. The results show that atherosclerosis in young adults is associated with the prediabetic or early diabetic state, as indicated by elevated glycohemoglobin levels, and with obesity.

Natural history and risk factors for early human atherogenesis. Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

A multi-institutional study, Pathobiological Determinants of Atherosclerosis in Youth (PDAY), was initiated to document the natural history of atherosclerosis, its relationship to risk factors, and the pathobiology of lesion development in young subjects. Pathology laboratories in nine centers collected arteries and tissues from > 2000 persons, ages 15-34 years, whose deaths were attributed to homicides, accidents, or suicides. Arteries were evaluated for lesions, and risk factors were analyzed in a central laboratory. Postmortem risk factors include serum lipoproteins, serum thiocyanate (smoking), glycohemoglobin (diabetes), thickness of panniculus adiposus (obesity), changes in small renal arteries (hypertension), and apoprotein isoforms. This PDAY study documents the development of atherosclerosis at an early age and shows that the recognized risk factors for coronary heart disease are associated with lesion development in the arteries of these young subjects. The findings provide a strong justification for reducing risk factors in young persons.

Natural history and risk factors for early human atherogenesis. Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

A multi-institutional study, Pathobiological Determinants of Atherosclerosis in Youth (PDAY), was initiated to document the natural history of atherosclerosis, its relationship to risk factors, and the pathobiology of lesion development in young subjects. Pathology laboratories in nine centers collected arteries and tissues from &gt; 2000 persons, ages 15-34 years, whose deaths were attributed to homicides, accidents, or suicides. Arteries were evaluated for lesions, and risk factors were analyzed in a central laboratory. Postmortem risk factors include serum lipoproteins, serum thiocyanate (smoking), glycohemoglobin (diabetes), thickness of panniculus adiposus (obesity), changes in small renal arteries (hypertension), and apoprotein isoforms. This PDAY study documents the development of atherosclerosis at an early age and shows that the recognized risk factors for coronary heart disease are associated with lesion development in the arteries of these young subjects. The findings provide a strong justification for reducing risk factors in young persons.

Long-term induction and regression of diet-induced atherosclerotic lesions in rhesus monkeys. II. Morphometric evaluation of lesions by light microscopy in coronary and carotid arteries

Atherosclerotic lesions were induced in rhesus monkeys (Macaca mulatta) by feeding them a high-saturated fatty acid and high-cholesterol diet. After 5.4 years the extent of lesions in three major coronary arteries and the right carotid artery was evaluated morphometrically by light microscopy in one group of animals (group P). The remaining animals were switched to a low-cholesterol diet that remained high in saturated fatty acids and provided the same percentage of total calories as did the atherogenic diet. Lesion regression was then evaluated in one group of monkeys 1.9 years (group R4) and in another group of monkeys 3.7 years (group R5) after withdrawal of cholesterol alone from the diet. In group P, the mean intimal thickness varied between 26 and 47 microns, maximum intimal thickness between 70 and 92 microns, and luminal reduction between 9% and 12% in the three major coronary arteries. Luminal reduction varied between 1% and 11% in right carotid artery segments. After 1.9 years of consuming the basal diet, group R4 animals were no different from group P animals with respect to morphometric measures. Total intimal and medial areas of the left anterior descending (LAD) coronary artery in groups P and R4 were also similar. In contrast, after 3.7 years of consuming the basal diet, group R5 animals showed consistently although not statistically significantly lower values than those in group P for the morphometric measures in coronary arteries and total intimal area in the LAD. Similar results were obtained for the common carotid and external carotid arteries. Thus, our study shows that long-term diet-induced lesions in coronary arteries and in common and external segments of the right carotid artery regressed only when the animals were fed the basal diet for 3.7 years. We conclude that atherosclerotic lesions induced in coronary and carotid arteries can regress toward normal to a certain extent, but they require a longer time for regression than do other arterial segments. These findings support the results of clinical trials in human subjects.

Long-term induction and regression of diet-induced atherosclerotic lesions in rhesus monkeys. I. Morphological and chemical evidence for regression of lesions in the aorta and carotid and peripheral arteries

Atherosclerotic lesions were induced in rhesus monkeys by feeding a high-saturated fatty acid and high-cholesterol diet. After 5.4 years the extent of fatty streaks and raised lesions was evaluated in one group of animals (group P) by visual estimation in 10 arterial segments and chemically in four arterial segments. The remaining animals were switched to a basal regression diet low in cholesterol but high in saturated fatty acids for up to 3.7 years. Regression of lesions was evaluated in one group for 1.9 years (group R4) and in another for 3.7 years (group R5) after deleting cholesterol from the diet. The atherogenic diet increased serum cholesterol levels in all animals from a mean of 150 mg/dL to a mean of about 430 mg/dL. The atherogenic diet produced lesions in group P in all arterial segments (involving up to 50% of the arterial intimal surface) and increased cholesterol content in four arterial segments (varying between 443 and 506 micrograms/cm2). Switching to the basal regression diet decreased serum cholesterol levels to normal after 12 to 18 weeks. The switch to the basal diet significantly decreased the extent of fatty streaks in most arterial segments in both groups. Although differences in the mean extent of raised lesions among groups were not statistically significant, 7 of 10 arterial segments in group R4 and 9 of 10 segments in group R5 showed a lesser extent of raised lesions than in group P. Cholesterol content was lower (P < .05) in all four arterial segments in group R5 than in group P.(ABSTRACT TRUNCATED AT 250 WORDS)

Atherosclerosis in young white males: arterial collagen and cholesterol

As part of a multicenter study on atherosclerosis, we examined defined segments of thoracic and abdominal aortas from 118 white males, age 15-34 years, who died from external causes. One half of each aorta specimen was graded for lesions. Intima-media preparations were assayed for collagen and cholesterol in two standardized regions (dorsal and ventral) derived from the alternate half of each segment. Even though the mean extent of intimal surface involvement with raised lesions remained minimal (0-6%), the data revealed a remarkable transition in vessel wall chemistry over this time span. For example, the amount of collagen per unit surface area increases with age in all vessel segments except the ventral domain of the thoracic aorta. The amount of collagen as a percent of total vessel protein rises with age only in the ventral and dorsal regions of the abdominal aorta. Free and esterified cholesterol levels per unit surface area increase with age in all vessel segments. There is a significant correlation between collagen and esterified cholesterol per unit surface area in all vessel regions with the exception of the abdominal ventral segment. In the latter segment increases in collagen per unit surface area occur without a corresponding increase in cholesterol level suggesting that connective tissue proliferation may actually precede lipid deposition in the genesis of atherosclerosis. Esterified cholesterol is present at higher levels in the dorsal domains of the thoracic and abdominal aortas than in the ventral domains. These findings provide chemical data confirming that the dorsal domains is the most lesion-prone region of these vessel segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Association of diabetes mellitus with coronary atherosclerosis and myocardial lesions. An autopsy study from the Honolulu Heart Program

While the excess risk of clinical cardiovascular disease among persons with diabetes mellitus is well established, most autopsy studies have not been able to elucidate reasons for the excess, to assess potential selection bias, or to adjust for other cardiovascular risk factors. The purpose of this study was to examine the predictive relation between diabetes and autopsy evidence of coronary atherosclerosis and myocardial lesions. Among 8,006 Japanese-American men examined at baseline in 1965-1968 as part of the Honolulu Heart Program, 7,591 were free of cardiovascular disease, and 1,515 of these men died over a 17-year follow-up period. Protocol autopsies were performed for 83 diabetic men and 159 nondiabetic men. Diabetes status was defined using self-reported history and treatment at several examinations, as well as physician diagnoses during hospitalization between 1965 and 1984. An excess of coronary artery atherosclerosis, assessed by mean panel score (3.4 vs. 3.0, p = 0.017) and percentage of intimal surface with raised lesions (56.6% vs. 47.4%, p = 0.024), was present among diabetic men but diminished to nonsignificant levels (3.3 vs. 3.0, p = 0.102, and 53.9% vs. 48.8%, p = 0.183, respectively) after adjustment for other cardiovascular risk factors. Myocardial lesions (acute, healing, or fibrotic) occurred significantly more frequently among diabetics than among nondiabetics (77.7% vs. 63.4%, p = 0.035), even after adjustment for other risk factors. Potential autopsy selection bias assessed in several ways appeared minimal. Among men with mild atherosclerosis, diabetics had more small and large myocardial lesions than did nondiabetics, although differences were not statistically significant (p < 0.10). It appears that the more adverse risk factor profile among diabetics accounts for some of the observed excess of coronary atherosclerosis. However, diabetes was independently associated with myocardial lesions, and these findings suggest a role for nonatherosclerotic mechanisms, such as clotting abnormalities or microvascular disease, in accounting for the excess clinical heart disease found in persons with diabetes.

Nephrosclerosis in three cohorts of black and white men born 1925 to 1944, 1934 to 1953, and 1943 to 1962

The prevailing levels of blood pressure among black and white men of ages 25 to 54 years were examined by two independent approaches in this study. Data on blood pressure obtained in national health surveys (National Health and Nutrition Examination Surveys, NHANES) do not show any appreciable upward or downward trend between 1960 and 1980 in men of these ages. The histologic examination of kidney samples obtained from coroner's autopsies offers an indirect way of estimating the levels of blood pressure that prevail in populations because of statistical relationships between nephrosclerosis and blood pressure. Samples of kidney tissues archived in New Orleans from 1968 to 1986 were evaluated by quantitative morphometry for the severity of the renovasculopathies that accompany high blood pressure. The outcome showed no significant secular trend among black and white men, confirming blood pressure survey findings that show no change in the hypertensive status of the population. The black-white difference in incipient signs of hypertension was seen to be well-established by ages 25 to 34 years in all cohorts of New Orleans subjects, as well as in the NHANES survey data. These result suggest that the adolescent and young adult ages are especially important in establishing the black-white difference in hypertension.

Atherosclerotic lesions. Natural history, risk factors, and topography

This article describes the development of human atherosclerosis as a framework on which to integrate and incorporate the research on thrombosis and hemostasis of participants in the 1992 College of American Pathologists Conference XXII on Hemostasis and Atherosclerotic Disease. Included are the early classic studies of the morphological features of atherosclerosis, atherosclerosis in different populations, the distribution of atherosclerotic lesions among arterial segments, the topography of atherosclerotic lesions within arterial segments, and the relationship of risk factors for coronary heart disease to the arterial lesions of atherosclerosis. Special attention is given to the development of atherosclerosis in young people, including findings from the Pathobiological Determinants of Atherosclerosis in Youth study. The data in this review provide confirmation of the development of atherosclerosis at an early age and relate atherosclerotic lesions to certain coronary heart disease risk factors. Any role of thrombosis or hemostasis in atherosclerosis must be integrated into this framework.

Atherosclerosis of the aorta and coronary arteries and cardiovascular risk factors in persons aged 6 to 30 years and studied at necropsy (The Bogalusa Heart Study)

Race and sex differences in aorta and coronary atherosclerotic lesions were studied in 150 persons aged 6 to 30 years. The intimal surface involvement with aorta fatty streaks was extensive, 0 to 71%, and greater in blacks than in whites (32 vs 20%, p less than 0.001). Coronary artery fatty streaks were more extensive in male than in female subjects (range 0 to 22%). Fibrous plaque lesions were present but not extensive in either the aorta (0 to 12%) or the coronary artery (0 to 24%) specimens. Lesions were more prevalent in male than in female persons, particularly white male subjects. The relation of fatty streaks to fibrous plaques was greater in the coronary vessels than in the aorta. In male subjects, aorta fatty streaks were strongly related to antemortem levels of total cholesterol, low-density lipoprotein cholesterol and ponderal index in white male subjects. Coronary artery fatty streaks in white male persons were significantly associated with serum triglycerides, very low density lipoprotein cholesterol, systolic and diastolic blood pressure and ponderal index. These results link antemortem risk factors to the development of atherosclerotic lesions and emphasize the need for preventive cardiology in early life.

Apo B insertion/deletion polymorphisms are associated with atherosclerosis in young black but not young white males. Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

Investigators in eight communities collected aortas, right coronary arteries, blood and liver samples, and associated information from 872 young males, aged 15-34 years, who died of external causes. Pathologists graded the arteries for atherosclerotic lesions, and a central laboratory measured lipoprotein cholesterol concentrations. Apolipoprotein (apo) B sequences were amplified in hepatic DNA samples to determine genotypes for length polymorphisms in the signal peptide of apo B. In addition to the insertion (ins) allele (27-amino acid signal peptide) and the deletion (del) allele (24 amino acids), we detected a rare allele (ins*) in whites with an in-frame insertion of two Leu codons in a region that normally contains six Leu codons. The frequency for the apo B del allele was lower in blacks than in whites (p less than 0.0001). In blacks, homozygotes for the ins allele had the lowest levels of serum cholesterol and very low plus low density lipoprotein cholesterol (VLDL + LDL-C), homozygotes for the del allele had the highest levels, and heterozygotes had intermediate levels (p = 0.0509 for cholesterol, p = 0.0530 for VLDL + LDL-C), but no differences were found in whites. In blacks, homozygotes for the ins allele had the least involvement of the thoracic and the abdominal aorta with lesions, homozygotes for the del allele had the greatest involvement, and heterozygotes had intermediate involvement (p = 0.0328 for thoracic aorta, p = 0.0104 for abdominal aorta), but no differences were found in whites.(ABSTRACT TRUNCATED AT 250 WORDS)

Early lesions of atherosclerosis in childhood and youth: natural history and risk factors

This paper traces the development of knowledge concerning early lesions of atherosclerosis and the relationship to risk factors in children, youth, and young adults. Autopsy studies have shown that atherosclerosis begins in childhood with the appearance of aortic fatty streaks. Aortic fatty streaks of some degree are present in practically all individuals from every human population. Coronary fatty streaks begin to form in adolescence. Most persons 20-29 years of age have coronary fatty streaks of some degree, regardless of sex, race, or national origin. While fatty streaking is clinically harmless and potentially reversible, progression to fibrous plaques and more advanced lesions often leads to a critical stage of atherosclerosis in which clinical disease develops. Development of fibrous plaques begins in the 20s. The most recent studies of atherosclerosis in youth and young adults provide additional details to establish the relationship of these lesions to serum lipids and lipoproteins and other identified risk factors for atherosclerosis and coronary heart disease in adults. One report shows that microscopic counterparts of fatty streaks occur in the left anterior descending coronary artery in the majority of children 10-14 years of age. Over 5% have more advanced microscopic lesions at this age. Autopsy studies of youth have shown that serum total cholesterol and low-density lipoprotein cholesterol levels are strongly related to aortic fatty streaks and the very-low-density lipoprotein cholesterol levels are positively correlated to coronary artery fatty streaks. Finally, a definitive report indicates that serum lipoprotein cholesterol concentrations and smoking are important determinants of the early stages of atherosclerosis in adolescents and young adults.

Serum total bile acid concentration in rhesus monkeys: effects of feeding cholesterol and inhibiting cholesterol absorption and synthesis

The serum total bile acid concentration was measured in rhesus monkeys fed diets practically free of cholesterol and with added cholesterol at two levels. Also, the effects of inhibiting cholesterol absorption by feeding plant sterols and inhibiting cholesterol synthesis by feeding triparanol upon the serum total bile acid levels were studied. Cholesterol feeding significantly increased the serum bile acid concentration. The serum bile acid level was decreased in the high responders fed plant sterols but only when the diet contained the highest level of cholesterol. In both groups serum bile acid levels were not altered when cholesterol biosynthesis was inhibited by feeding triparanol. It is suggested that cholesterol feeding increases the serum bile acid level probably due to an increase in the intestinal pool of bile acids as a result of increased production of bile acids in the liver and their excretion into the bile.

Use of serum lipid and apolipoprotein concentrations to predict extent of diet-induced atherosclerotic lesions in aortas and coronary arteries and to demonstrate regression of lesions in individual rhesus monkeys

In most studies, the assessment of lesion "regression" is based on comparisons of group means between the "progression" and regression groups. This comparison depends on the assumption that the extent and distribution of lesions produced by the end of the lesion-induction period in the regression animals are equal to those observed in the progression group. To determine whether significant regression of lesions occurs in an individual regression animal, it is necessary to obtain a measure of the lesions produced in these animals at the end of the lesion-induction period. We achieved this goal by developing models using multiple stepwise regression analysis that related steady-state serum cholesterol and apolipoprotein B and A-I concentrations measured during a lesion-induction period in 27 rhesus monkeys fed an atherogenic high-saturated-fat/high-cholesterol diet for 2 years. The models were developed to estimate the percent of intimal surface with lesions, the esterified cholesterol content (micrograms/cm2) for the artery segments, and three histomorphometric measures (mean intimal thickness, mean maximal intimal thickness, and mean percent stenosis) for the coronary arteries. In these models, multiple R2 ranged from 0.42 to 0.74 for the aortas and peripheral arteries, indicating that approximately one half to three fourths of the variance in lesions was accounted for. For the three histomorphometric measures in coronary arteries, however, the multiple R2 was 0.27 or 0.28, indicating that only approximately one fourth of the variance in lesions was accounted for.(ABSTRACT TRUNCATED AT 250 WORDS)

Variations with age and serum cholesterol level in the topographic distribution of macroscopic aortic atherosclerotic lesions as assessed by image analysis methods

The topographic distribution of macroscopic atherosclerotic lesions in the aorta was studied by image analysis of aortas taken at autopsy from 155 males aged 10 to 54 yr. In both the thoracic and abdominal aorta, fatty streaks (FS) appear before raised lesions (RL) affecting preferential areas located longitudinally along the intercostal ostia, at the aorta bifurcation, and surrounding the points of origin of branches of the abdominal aorta. Later RL appear in the same areas of the aortic intima affected by FS at younger ages. As for the effect of serum total cholesterol (TC) in the progression of atherosclerosis, the prevalent involvement areas by FS and RL were similarly distributed as indicated by our analyses. However, areas showing frequent occurrence of FS and RL in each aortic segment were distributed more extensively at identical areas in the higher serum TC groups than in the lower TC level group. Thus, it can be concluded that FS are the precursor lesions of RL in the aorta and that the serum TC promotes the progression of atherosclerosis.

Changes in plasma lipoprotein concentrations and compositions upon feeding cholesterol in high- and low-responding rhesus monkeys

When fed cholesterol, the high-responding rhesus monkeys develop severe hypercholesterolemia, whereas low-responding rhesus monkeys show only slight increases in plasma cholesterol levels. We report changes in plasma lipoprotein concentrations and compositions along with changes in plasma lipid concentrations in high- and low-responding rhesus monkeys fed a high-cholesterol diet. On low-cholesterol diet, the concentrations and compositions of plasma lipoprotein fractions were similar in the two groups. Upon feeding cholesterol, plasma very-low-density (VLDL), intermediate-density (IDL) and low-density (LDL)-lipoprotein concentrations increased in both groups, but the increases were significantly (p less than 0.01) higher in high-responders than in low-responders. Plasma HDL concentration decreased significantly (p less than 0.01) in high responders but not in low responders. In high responders, percent cholesterol increased in both VLDL and IDL fractions but in low responders, it decreased in VLDL and increased in IDL. Percent triglycerides decreased in VLDL, IDL and LDL fractions in high responders, while in low responders it tended to increase in VLDL, remained unchanged in IDL and decreased in LDL. The composition of HDL did not change in the two groups upon feeding cholesterol. Thus, when fed cholesterol, the high- and the low-responding monkeys respond distinctly differently in plasma lipoprotein concentrations and compositions. The responses occurred simultaneously, suggesting metabolic interrelationships between various lipoproteins.

Fatty acid composition of adipose tissue in humans: differences between subcutaneous sites

We compared the fatty acid composition of adipose tissue from three different sites, one deep-seated site (perirenal) and two subcutaneous sites (abdominal and buttock), in 143 autopsied adult humans aged 24-61 y. The proportion of saturated fatty acids was highest in the perirenal adipose tissue and lowest in buttock adipose tissue. The proportions of monounsaturated fatty acids in the three sites were in the reverse order. Linoleic and linolenic acids were similar in the three adipose-tissue sites, an important finding for those concerned about the essential fatty acids, which are solely derived from the diet. The results clearly show that the fatty acid composition of the two subcutaneous fat depots differ significantly. We conclude that abdominal fat is more saturated than buttock fat.

Serum lipids and lipoproteins as predictors of atherosclerosis. An autopsy study

A prospective study of autopsy-determined measures of atherosclerosis in aortas and coronary and cerebral arteries was completed for a group of 83 men who were free of clinical cardiovascular disease and cancer when they entered the Cooperative Lipoprotein Phenotyping Study in 1970. Total cholesterol minus high density lipoprotein cholesterol (HDL-C) was significantly associated with measures of atherosclerosis in all three groups of vessels. The patterns of associations for total, low density lipoprotein, and very low density lipoprotein cholesterol were similar but generally weaker and not significant for atherosclerosis in the cerebral arteries. Inverse associations of HDL-C with atherosclerosis in the circle of Willis and aorta were significant, but those for the coronary arteries were not. These associations were independent of other major risk factors for atherosclerosis in multivariate analyses. Similarities between these findings and those for clinical cardiovascular disease in the same cohort indicate that the opposing patterns of increased risk of clinical cardiovascular disease associated with total cholesterol and the decreased risk associated with HDL-C also exists at the level of atherosclerosis in a variety of arteries.

Is atherosclerosis increasing in Mexico City?

This report compares quantitative measures of atherosclerosis in aortas and coronaries from autopsies of deceased men from Mexico City collected during 1960 to 1964 and 1986 to 1987. The comparison of lesions in two different time periods provides an opportunity for determining whether the extent of atherosclerosis has changed over time in Mexico City. Three pathologists independently evaluated the extent of fatty streaks (FS), fibrous plaques (FP), calcified plaques (CA), and complicated lesions (CO) in 165 aortas and 120 sets of coronary arteries collected during 1986 to 1987 for comparison with similar gradings of 128 aortas and coronary arteries from the International Atherosclerosis Project in 1960 to 1964. Neither FS nor more advanced lesions differed significantly in either the descending thoracic or abdominal aorta between the two collection periods. In contrast, there were more extensive FP and raised atherosclerotic lesions (RL = FP + CA + CO) in the coronary artery segments evaluated in the younger age groups in 1986 to 1987 versus 1960 to 1964. Additional analyses, based on 75 pairs of aortas and 32 pairs of coronary arteries from age-matched cases, all regraded by the team of pathologists after blind coding, showed more FS in both aortic segments and more extensive involvement with RL in the three main branches of the coronary arteries in the more recent study. An overview of our findings suggests that atherosclerosis, particularly in the coronary arteries, is increasing in Mexico City. This hypothesis merits careful testing in parallel with consideration of possible changes in the risk factors that could be responsible for changes in extent of lesions.

Effect of cholesterol feeding on lipolytic activities in high- and low-responding rhesus monkeys

We compared the activities of lipoprotein (LPL) and hepatic lipase (HL) in postheparin plasma in groups of high- and low-responding rhesus monkeys fed a low cholesterol diet followed by a high cholesterol diet. Cholesterol feeding resulted in a two-phase response in lipolytic activities: an initial phase lasting about 21 days that was similar in the two groups, followed by the second phase in which major differences became apparent between the groups. In the initial phase, LPL and HL activities increased along with plasma cholesterol and high density lipoprotein (HDL) cholesterol, but there was no change in plasma triglycerides or apolipoprotein (apo) A-I levels. These changes suggest that both high and low responders respond in a similar manner to metabolize an increased lipid load and that both groups continue to remove triglyceride efficiently while cholesterol accumulation begins. The second phase (between 21 and 42 days and thereafter) in high responders was characterized by a decrease in LPL and HL activities along with plasma HDL cholesterol and apo A-I levels, continued increase in plasma cholesterol, and a slow increase in plasma triglycerides. In low responders, LPL activity was maintained at a high level, HL activity decreased to the basal level, and plasma lipids were unchanged. All changes occurred simultaneously, suggesting metabolic relationships between plasma lipolytic activities, plasma lipids, and apolipoprotein.