A study of atherosclerosis regression in Macaca mulatta. V. Changes in abdominal aorta and carotid and coronary arteries from animals with atherosclerosis induced for 38 months and then regressed for 24 or 48 months at plasma cholesterol concentrations of 300 or 200 mg/dl

Young adult male rhesus monkeys (Macaca mulatta) were fed an atherogenic diet for 38 months. After 38 months of atherosclerosis induction, a baseline group was selected and necropsied to determine the extent and severity of atherosclerosis before regression regimens were begun. The remaining animals were fed diets that varied in cholesterol concentration in order to maintain plasma cholesterol concentrations of approximately 200 or 300 mg/dl for either 24 or 48 months. The progression or regression of atherosclerosis in coronary arteries, abdominal aorta, and carotid arteries was determined by comparing them to the baseline group. Coronary artery atherosclerosis regressed in the majority of animals after 4 years but not after 2 years when plasma cholesterol concentrations were about 200 mg/dl. Among the animals maintained at plasma cholesterol concentrations of about 300 mg/dl, about half the animals progressed in the extent of coronary artery atherosclerosis while about half regressed. The majority of the animals that progressed in lesion extent were genetic hyperresponders to dietary cholesterol whereas those that regressed were predominantly hyporesponders, even though their plasma lipid concentrations were equivalent during the regression phase. The changes seen in atherosclerosis extent in the abdominal aorta were quite similar to the changes seen in coronary arteries. Changes at this site were not pronounced after 2 years, but after 4 years animals with plasma cholesterol concentrations of about 300 mg/dl progressed while the animals at 200 mg/dl were mostly unchanged. No evidence for atherosclerosis regression was found in the common carotid arteries or in the carotid bifurcations.     

去纤酶对防止家兔实验性动脉粥样硬化斑块形成的作用

目的 研究去纤酶是否具有防止家兔实验性动脉粥样硬化斑块形成的作用。方法 对给药组及对照组模型动物血清总胆固醇含量,主动脉病变面积有胆固醇含量,心壁冠状动脉分支狭窄程度进行定性或定量分析。结果 去纤酶能降低血清及动脉壁的胆固醇含量（Ｐ〈０．０１）,斑块面积明显小于模型对照组（Ｐ〈０．０１）,在胸腹主动脉区各动脉分支开口愉形成计数中,给药组明显少于对照组,心脏上１／３处横切片显示心壁内冠状动脉大,中分     

冠状动脉病变程度与血浆B型利钠肽对冠心病的影响因素

目的 探讨冠心病患者冠状动脉病变程度与血浆B型利钠肽的关系。方法 选择我院2017年1月~8月住院的冠心病患者54例为A组,同时选择冠脉血管无狭窄的患者26例作为B组,收集所有研究对象的年龄、性别、血糖、血脂、血压、血浆脑钠肽（BNP）浓度、冠状动脉的病变部位及程度等临床资料,观察不同程度冠状动脉病变患者的血浆BNP水平。结果 血浆BNP水平A组较B组升高,统计学意义显著（P＜0.001）。Logistic回归分析显示,年龄、BNP水平、舒张压是冠状动脉狭窄的独立危险因素。在A1、A2及A3组中随着Gensini评分增加,血浆BNP水平逐渐升高,Gensini评分与血浆BNP水平呈明显的正相关（r=0.594,P＜0.05）。结论 血浆BNP参与了冠状动脉狭窄的病理生理过程,是冠状动脉病变的独立危险因素之一;血浆BNP的水平能一定程度上的反映冠脉病变程度。     

Effects of exercise training on pathological cardiac hypertrophy related gene expression and apoptosis

This study determined whether exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial and apoptosis-associated genes. We used spontaneously hypertensive rats (n=15, non-exercise SHR), exercise-trained SHR (n=15, treadmill exercise for 12 weeks), and sedentary Wistar-Kyoto (WKY) rats (n=15). Exercise-trained SHR expressed adaptive changes such as reduced body weight, heart rate, blood pressures, left ventricle wall thickness, lipid profiles, and homocysteine level. The mRNA expression of angiotensin converting enzyme, endothelin-1, and brain natriuretic peptides in the heart was lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR, whereas mRNA expression of caveolin-3 and eNOS in the heart was higher. Bcl-2 protein was higher in the exercise-trained SHR than in the WKY and the non-exercise SHR. In contrast, Bax protein levels were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. Furthermore, the levels of the active forms of caspase-3 (20 kDa) were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. These findings suggest that exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial genes and that it interferes with a signal transduction pathway of apoptosis secondary to the pathological cardiac hypertrophy.     

Advanced coronary atherosclerosis in swine produced by combination of balloon-catheter injury and cholesterol feeding.

There has been a constant demand for an animal model of advanced coronary atherosclerosis produced in a short period. It was known that mild atherosclerosis could be produced in various vascular beds by high cholesterol diets. However, it requires considerable time to produce advanced atherosclerotic lesions by diets alone. The current study was designed to investigate effects of combination of a balloon-denudation procedure and high cholesterol diet in swine. We could produce advanced atherosclerotic lesions in coronary arteries in cholesterol-fed swine within a short period of time by inserting a balloon-catheter via carotid artery into the coronary artery, inflating it so as to distend the lumen, and pulling it back quickly, which resulted in extensive denudation of the endothelium of coronary arteries. An atherosclerosis-like lesion develops at the site with eventual narrowing of the lumen leading to myocardial ischemia, myocardial infarction, and occasionally sudden death, thus resembling in many aspects human coronary artery disease. Among 22 swine studied, 10 had severe atherosclerosis with virtual occlusion of proximal portion of either or both coronary arteries and developed myocardial infarction within 2–3 months. Seven of these died suddenly, probably due to arrhythmia. This model should be appropriate for studies where advanced coronary atherosclerosis with its complications is needed.     

黄酒和红葡萄酒抑制LDLR~(-/-)小鼠MMP-2表达和动脉粥样硬化斑块形成

目的:观察黄酒是否能减轻动脉粥样硬化斑块的形成并探讨其可能机制。方法:48只6周龄LDLR-/-小鼠,以高脂+高蛋氨酸(标准饲料+10%油脂+1.25%胆固醇+1%L-蛋氨酸)喂养诱导形成高同型半胱氨酸血症并致动脉粥样硬化模型,随机分为:黄酒组、红葡萄酒组、酒精组和对照组,每组12只。14周后处死小鼠,检测血脂及血浆同型半胱氨酸;观察胸腹主动脉和主动脉窦部粥样硬化情况;免疫组化测定主动脉窦部MMP-2的表达;明胶酶谱法测定MMP-2的活性。结果:(1)4组间TC、TG、HDL-C水平无显著差别(P0.05),黄酒组血浆HCY分别较对照组、酒精组和红葡萄酒组显著下降(P0.01)。(2)与对照组比较,主动脉粥样硬化斑块面积黄酒组、红葡萄酒组和酒精组分别减少了33.7%、35.9%(P0.01)和6.5%(P0.05);与酒精组比较,黄酒组和红葡萄酒组主动脉粥样硬化面积差别同样显著(P0.01)。分别与对照组和酒精组比较,黄酒组和红葡萄酒组主动脉窦部粥样硬化面积减少同样显著差异(P0.01),黄酒组和红葡萄酒组间无显著差异(P0.05)。(3)与对照组比较,MMP-2的表达在黄酒组、红葡萄酒组和酒精组分别减少了26.3%、27.6%(P0.01)和5.7%(P0.05);MMP-2的活性在黄酒组、红葡萄酒组、酒精组分别减少了31.7%、32.5%(P0.01)和6.7%(P0.05)。结论:黄酒和红葡萄酒均能抑制MMP-2的表达和减轻动脉粥样硬化斑块的形成,这可能是它们对心血管系统保护作用的机制之一。     

Population dynamics of arterial cells during atherogenesis: XII. Reversal of endothelial cell loss over atherosclerotic aortic lesions in swine changed to normolipidemic-regression diet

Cell kinetics of arterial endothelial cells were studied in the 105- to 165-day period after the initiation of atherosclerosis in swine abdominal aorta by balloon denudation followed by a hyperlipidemic diet. One group of swine was continuously on a hyperlipidemic diet from Day 0 to Day 165; another group on Day 60 was placed on a normolipidemic mash diet. Between Days 105 and 165, the amount of endothelial cell loss over lesion areas in the hyperlipidemic group was approximately 40%, while virtually no loss occurred over lesion areas in the group placed on the mash diet at Day 60. This diet, when fed for 14 months, is known to produce regression of atherosclerosis in swine. Continuous endothelial cell loss of abnormal amount, as occurred over lesion areas of the hyperlipidemic group in this study, may result in a breach (albeit a transient one) in the endothelial cell barrier, and allow the entry of injurious substances such as platelets or lipoproteins which enhance the development of atherosclerosis. The reversal of this endothelial cell loss by a mash diet is possibly one of the first events in the regression of the atherosclerotic lesion.     

Low dose estrogens inhibit coronary artery atherosclerosis in postmenopausal monkeys

OBJECTIVES: To determine if low dose conjugated equine estrogens (CEE) result in a reduction of coronary artery atherosclerosis progression, and to relate these findings to previous studies using the traditional dose. METHODS: Adult female monkeys (Macaca fascicularis) were fed an atherogenic diet for 10 months, to induce fatty streaks and small plaques comparable to those present in early postmenopausal women, and then ovariectomized and treated orally with: CEE (0.30 mg/day women's equivalent dose, n=28) or placebo (n=25) daily for 24 months. Body weight and estradiol were measured at 3, 6, 12 and 18 months and plasma lipids were measured at baseline and every 6 months. RESULTS: Despite the lack of effect on plasma lipid profiles, monkeys treated with low dose CEE had marked reductions in coronary artery atherosclerosis plaque extent (intimal area) in all three main coronary arteries: left anterior descending artery (52% less, 0.044 mm(2) versus 0.091 mm(2), p=0.04); left circumflex artery (62% less, 0.045 mm(2) versus 0.119 mm(2), p=0.006) and right circumflex artery (42% less, 0.018 mm(2) versus 0.031 mm(2), p=0.20). The overall mean coronary atherosclerosis extent was 52% lower in CEE treated animals (0.042 mm(2) versus 0.088 mm(2), p=0.02). CONCLUSION: Low dose CEE (0.30 mg/woman/day equivalent) was effective in reducing coronary atherosclerosis and the magnitude of the protection was comparable to previously reported studies using doses equivalent to 0.625 mg/woman/day. This study provides an experimental basis for the assumption that low dose CEE may be as effective as the traditional dose in inhibiting coronary atherosclerosis progression in early postmenopausal subjects.     

Attenuation of stress-induced hypertension by exercise independent of training effects: An animal model

The present study attempted to determine if exercise, in the absence of physical training, could alter development of hypertension during chronic exposure to a psychosocial stressor. Two groups of genetically normotensive rats were exposed to social stress for 7 days, following 5 weeks of acclimation to social isolation. One group had access to exercise in a running wheel during the stress period, while the second group did not. Blood pressure, heart rate, body weight, and running activity were monitored throughout the study, and heart and adrenal gland weights were obtained following sacrifice of the animals after exposure to stress. Blood pressure increased significantly to hypertensive levels on days 4 and 7 in the group denied access to exercise but was unchanged in the exercise group. Degree of attenuation of stress-induced hypertension was unrelated to amount of running activity. There were no differences in body weight, heart rate, or organ weight between groups. Exercise appeared to act specifically via diversional, or coping, mechanisms to buffer the response of the body to stress.This work was supported by a grant from the Heart and Stroke Foundation of Ontario.     

Conditioning exercise decreases premenstrual symptoms

Summary Conditioning exercise decreased premenstrual symptoms during 3 months of a prospective controlled training study. Eight women with normal ovulatory menstrual cycles began a running exercise training programme while completing intensity-graded questionnaires concerning molimina. Six sedentary control women followed the same protocol for 3 months but did not exercise. Oral basal temperatures evaluated by mean temperature analysis were obtained for all cycles. Exercise distance and time, average exercise heart rate, basal and maximal heart rate and body weights were recorded prospectively and evaluated during the control (0) and 3rd month of the study. Mid-luteal phase progesterone and estrogen levels were sampled during the analyzed cycles for the exercise group.Molimina did not change over 3 months time in the control group. The exercise group, after increasing distance run to 51.0±18.1 km/cycle at 3 months, showed decreases in overall molimina (scores on a 9-point scale) 6.5±1.8 to 3.5±0.9, p<0.01). Breast symptoms decreased from 8.3±0.7, p<0.005. Fluid symptoms also decreased from 7.3±1.8 to 5.5±0.9, p<0.025.Menstrual cycle intervals, luteal lengths, body weights and mid-luteal estrogen and progesterone levels were normal and unchanged. Moderate exercise training without major weight, hormonal or menstrual cycle alteration significantly decreased premenstrual symptoms.     

Aerobic exercise improves the inflammatory profile correlated with cardiac remodeling and function in chronic heart failure rats

OBJECTIVE:

The aim of the present study was to evaluate the effect of 8 weeks of aerobic exercise training on cardiac functioning and remodeling and on the plasma levels of inflammatory cytokines in chronic heart failure rats.

METHODS:

Wistar rats were subjected to myocardial infarction or sham surgery and assigned to 4 groups: chronic heart failure trained (n = 7), chronic heart failure sedentary (n = 6), sham trained (n = 8) and sham sedentary (n = 8). Four weeks after the surgical procedures, the rats were subjected to aerobic training in the form of treadmill running (50 min/day, 5 times per week, 16 m/min). At the end of 8 weeks, the rats were placed under anesthesia, the hemodynamic variables were recorded and blood samples were collected. Cardiac hypertrophy was evaluated using the left ventricular weight/body weight ratio, and the collagen volume fraction was assessed using histology.

RESULTS:

The chronic heart failure trained group showed a reduction in left ventricular end-diastolic pressure, a lower left ventricular weight/body weight ratio and a lower collagen volume fraction compared with the chronic heart failure sedentary group. In addition, exercise training reduced the plasma levels of TNF-α and IL-6 and increased the plasma level of IL-10.

CONCLUSION:

An 8-week aerobic exercise training program improved the inflammatory profile and cardiac function and attenuated cardiac remodeling in chronic heart failure rats.     

Rehabilitation training improves exercise tolerance after percutaneous coronary intervention

The aim of this present study was to investigate the effects of training on exercise tolerance of patients with coronary heart disease after percutaneous coronary intervention.Fifty-seven cases of coronary heart disease after percutaneous coronary intervention were divided randomly into the rehabilitation training group(26 cases) and control group(31 cases).Patients in the rehabilitation training group received rehabilitation training at different stages and exercise intensities 3 d after percutaneous coronary intervention for 3 months.The heart rate,blood pressure,ECG changes in treadmill exercise test,and the frequency of anginal episodes were observed.The results showed that NST and ΣST of ECG and the frequency of anginal episodes were significantly reduced in the rehabilitation training group.In addition,exercise tolerance was improved and the total exercise time was lengthened in these patients.Moreover,ST segment depression time and emergence time of angina with exercise were also lengthened compared with controls(P < 0.05,or 0.01).However,the heart rate and blood pressure before and after exercise of the two groups were similar.The study indicated that rehabilitation training could significantly relieve angina,amend ischemic features of ECG,and improve exercise tolerance of coronary heart disease patients after percutaneous coronary intervention.     

Treadmill exercise training fails to reverse defects in glucose, insulin and muscle GLUT4 content in the db/db mouse model of diabetes

OBJECTIVE: Regular exercise is recommended for the treatment of type 2 diabetes because of the benefits on body weight and glycemic control. The present study was designed to compare the impact of voluntary wheel and forced treadmill running on the metabolic state in the db/db mouse model of type 2 diabetes. Our hypothesis is that voluntary exercise training reduces body weight, blood glucose and insulin levels and restores GLUT4 levels in skeletal muscle, whereas forced exercise training produces a greater effect. STUDY DESIGN: Male diabetic db/db mice were assigned to sedentary (DS), voluntary wheel running (DV), and forced treadmill running (DT) groups for 12 weeks. Nondiabetic heterozygote littermates served as control (CN). RESULTS: Over the 12-week period, DV and DT mice ran a total of 4.24+/-0.18km and 11.8km, respectively. At week 12, fasting plasma glucose was decreased in DV mice compared to DS mice and occurred in the absence weight loss. In DT mice, body weight and fasting plasma glucose were not improved with exercise when compared to DS mice and were actually higher compared to DV mice. After training, fasting plasma insulin was increased in DS mice compared to CN mice and training failed to normalize plasma insulin levels. Gastrocnemius GLUT4 content was reduced in DS mice compared to CN mice and training had no effect in preventing this depression from occurring. CONCLUSION: The results of this study indicate that while voluntary exercise improved only blood glucose, forced treadmill exercise training failed to restore body weight, blood glucose and insulin, and muscle GLUT4 content.     

Increases in lipids and immune cells in response to exercise and mental stress in patients with suspected coronary artery disease: effects of adjustment for shifts in plasma volume

This study examined the role of shifts in plasma volume on lipid and immune reactions to stress. Lipid, immune, rheological, and cardiovascular reactions to exercise and mental stress in 51 patients with suspected coronary artery disease were determined. Blood pressure and heart rate were measured during and blood samples taken at the end of each rest and task. Lipids (total cholesterol, triglycerides, HDL, LDL) and immune cells (lymphocytes, monocytes, granulocytes) increased with exercise, whereas cholesterol, LDL, and lymphocytes increased with mental stress. Plasma volume decreased by 1 and 5% following mental and exercise stress, respectively. The task-induced increases in lipids were no longer statistically significant following adjustment for changes in plasma volume, whereas the increases in immune cell numbers survived such correction. This study provides evidence that, in coronary artery disease patients, exercise and mental stress-induced increases in lipids but not immune cells can be largely accounted for by shifts in plasma volume.     

Role of the Adrenergic Nervous System in Development of Training-Induced Bradycardia

Sprague-Dawley rats, normal and chemically sympathectomized with 6-hydroxy-dopamine, were trained by treadmill running. The normal rats, unlike the sympathectomized animals, showed reduction of the exercise heart rate after the training period. Compared to a sedentary control group the sympathectomized rats showed no difference in intrinsic heart rate after pithing and denervation and no increase in heart weight. The increase of the heart weight/body weight ratio after training was smaller in the sympathectomized group than in the normal one. The results show that a functioning adrenergic nervous system is necessary for an efficient adaptation to physical training. Administration of noradrenaline to pithed trained and untrained rats showed that betaadrenergic receptor sensitivity was not altered by physical training. The intrinsic heart rate of normal trained rats was lower than that of normal control rats.     

Role of the adrenergic nervous system in development of training-induced bradycardia.

Sprague-Dawley rats, normal and chemically sympathectomized with 6-hydroxy-dopamine, were trained by treadmill running. The normal rats, unlike the sympathectomized animals, showed reduction of the exercise heart rate after the training period. Compared to a sedentary control group the sympathectomized rats showed no difference in intrinsic heart rate after pithing and denervation and no increase in heart weight. The increase of the heart weight/body weight ratio after training was smaller in the sympathectomized group than in the normal one. The results show that a functioning adrenergic nervous system is necessary for an efficient adaptation to physical training. Administration of noradrenaline to pithed trained and untrained rats showed that betaadrenergic receptor sensitivity was not altered by physical training. The intrinsic heart rate of normal trained rats was lower than that of normal control rats.     

MTHFR基因多态性与中年男性冠状动脉病变程度的相关研究

目的 探讨四氢叶酸还原酶C677T基因多态性与中年男性冠状动脉病变程度。方法 选择2015年1月~2016年10月经冠脉造影确诊的128例山东沿海地区汉族中年男性冠心病患者（冠脉狭窄＞50%）,其中急性心肌梗死36例,按照国际心脏病学会和WHO冠心病诊断标准将128例冠心病患者分为急性冠脉综合征（ACS）组67例和稳定性心绞痛（SAP）组61例,并选110例冠脉正常者作为对照组。通过循环酶法测定血浆同型半胱氨酸浓度和PCR荧光法检测MTHER C677T基因型,观察血浆同型半胱氨酸浓度和MTHFRC677T基因型分布与冠脉病变的关系。结果 冠心病组血浆同型半胱氨酸水平明显高于对照组,差异有统计学意义（P＜0.01）,ACS组明显高于SAP组,差异有统计学意义（P＜0.01）。冠状动脉三支病变组血浆同型半胱氨酸水平明显高于单支病变组,差异有统计学意义（P＜0.01）,且高于双支病变组,差异有统计学意义（P＜0.05）。另外,双支病变组高于单支病变组,差异有统计学意义（P＜0.05）。冠心病组TT基因型、T等位基因频率明显高于对照组,差异有统计学意义（P＜0.01）;CT基因型高于对照组,差异有统计学意义（P＜0.05）。ACS组TT基因型高于SAP组,差异有统计学意义（P＜0.05）,T等位基因频率明显高于SAP组,差异有统计学意义（P＜0.01）。冠状动脉三支病变组TT基因型、T等位基因频率高于单支病变组,差异有统计学意义（P均＜0.05）。结论 MTHERC677T基因多态性及血浆同型半胱氨酸浓度参与山东沿海地区汉族中年男性冠状动脉粥样硬化病变的发生发展,且与冠脉病变严重程度有关。     

Behaviorally induced heart rate reactivity and atherosclerosis in cynomolgus monkeys

It has been suggested that individual differences in behaviorally induced cardiovascular reactivity may mediate associations between behavioral factors and atherosclerotic disease. The present study provides data relevant to this hypothesis within an animal model. Experimental animals were 26 adult, male cynomolgus monkeys that had been fed a moderately atherogenic diet for 22 months. In the weeks preceding termination of these animals, monkeys were fitted with electrocardiogram (EKG) telemetry devices and their heart rates (HRs) recorded under baseline and stressed conditions. Stress-period HR measures were obtained during a standard challenge involving threatened capture and physical handling of the animals. At necropsy, the coronary arteries were subjected to pressure fixation and sections taken from the left main, left anterior descending, left circumflex, and right coronary arteries. Mean intimal area measurements, calculated for each artery, were then compared between animals identified as High (n = 8) and Low (n = 8) HR reactors during stress. Results indicated that High HR reactors had significantly greater coronary artery atherosclerosis than did Low HR reactive animals, both in individual arteries and on an overall coronary index. Atherosclerosis in the thoracic aorta was found to differ similarly between High and Low HR reactors. Additional analyses revealed that High HR reactors were significantly more aggressive, more ponderous, and had greater heart weights than did Low HR reactors. Although groups did not differ in resting HRs, body weights, or lipid values, high-density lipoprotein (HDL) cholesterol comprised a slightly smaller fraction of the total serum cholesterol of High, relative to Low, HR reactive monkeys. It is concluded that these findings provide initial support for the hypothesis that cardiovascular hyperresponsiveness under stress is related to the development of atherosclerosis.     

运动训练改善心力衰竭大鼠动脉压力反射功能

目的:探讨运动训练(EX)对慢性心力衰竭(CHF)大鼠动脉压力反射功能的影响及机制。方法:实验分4组:心衰-运动组(EX-CHF),心衰-非运动组(CHF),假手术-运动组(EX-sham),假手术-非运动组(sham)。采用结扎左冠状动脉诱发心衰,然后进行4周跑步运动,检测压力反射(BR)、血浆血管紧张素II(AngII)和中枢AngIIⅠ型受体(AT1R)表达。结果:(1)CHF大鼠BR曲线平均斜率和最大增益明显小于sham大鼠(P0.01),EX增强CHF大鼠BR曲线平均斜率和最大增益(P0.05),但对sham组BR曲线无明显影响。(2)EX降低CHF大鼠血浆AngII浓度[(137±27)ng/Lvs(263±55)ng/L,P0.01],但不影响sham大鼠血浆AngII[(75±17)ng/Lvs(92±21)ng/L]。(3)CHF大鼠PVN内AT1R蛋白表达明显高于sham组(1.20±0.21vs0.70±0.14,P0.01),EX显著降低CHF大鼠室旁核内AT1R蛋白表达(0.90±0.13,P0.05),对sham大鼠AT1R表达(0.60±0.16)无明显影响。结论:运动训练改善心衰时减弱的动脉压力反射功能,其机制涉及降低血浆AngII和下调室旁核内AT1R蛋白表达。     

Atherosclerosis in Macaca mulatta: Histopathological,morphometric, and histochemical studies in aorta and coronary arteries of spontaneous and induced atherosclerosis

A comparative study of morphology, size, and histochemistry of the intimal lesions in aorta and coronary arteries of spontaneously occurring and cholesterol-induced atherosclerosis in rhesus monkeys has been carried out. A group of 30 normal monkeys was also investigated. Spontaneous atherosclerosis was noted in 10 of 55 adult monkeys autopsied serially; fatty streaks or atheroma in the aorta was noted in seven, fibrous plaque was noted in two, and diffuse intimal thickening was observed on one animal only. The coronary arteries showed fibrous intimal thickening without lipid in 8 of these 10 monkeys. There was fair to heavy deposition of acid mucopolysaccharides in the thickened intima along with proliferation of myointimal cells and collagen fibers. In the seven monkeys which were fed an atherogenic diet for 6 months, the aorta showed fatty streaking and atheroma in all animals. The coronary arteries also showed a variable degree of atherosclerosis but the lipid in the thickened intima was not marked. The atherosclerotic plaque height was not significantly greater than that in the spontaneous disease. These differences between spontaneously occurring and cholesterol-induced atherosclerosis in monkeys tend to indicate that the basic mechanism of lesion formation in the two states may be different.