Dexter L. Jung

Bio: Dexter L. Jung is an academic researcher from Stanford University. The author has contributed to research in topics: Population & Cancer. The author has an hindex of 14, co-authored 14 publications receiving 4083 citations.

The association of changes in physical-activity level and other lifestyle characteristics with mortality among men.

Abstract: Background Recent trends toward increasing physical exercise, stopping cigarette smoking, and avoiding obesity may increase longevity. We analyzed changes in the lifestyles of Harvard College alumni and the associations of these changes with mortality. Methods Men who were 45 to 84 years of age in 1977 and who had reported no life-threatening disease on questionnaires completed in 1962 or 1966 and again in 1977 were classified according to changes in lifestyle characteristics between the first and second questionnaires. We analyzed changes in their level of physical activity, cigarette smoking, blood pressure, and body weight, and the relation of these factors to mortality between 1977 and 1985. Results Of the 10,269 men, 476 died during this period (which totaled 90,650 man-years of observation). Beginning moderately vigorous sports activity (at an intensity of 4.5 or more metabolic equivalents) was associated with a 23 percent lower risk of death (95 percent confidence interval, 4 to 42 percent; P = 0.0...

Physical activity and incidence of hypertension in college alumni

Abstract: In a study population of 14,998 Harvard male alumni, 681 hypertensives were first diagnosed during a 6-10-year follow-up beginning 16-50 years after college entrance. The study comprised 105,662 man-years of observation of these men who had entered college in 1916-1950, and who were followed from 1962 or 1966 to 1972. Presence or absence of a background of collegiate sports did not influence risk of hypertension in this study population, nor did stair-climbing, walking, or light sports play by alumni. But, alumni who did not engage in vigorous sports play were at 35% greater risk of hypertension than those who did, and this relationship held at all ages, 35-74 years. Higher levels of body mass index, weight gain since college, history of parental hypertension, and lack of strenuous exercise independently predicted increased risk of hypertension in alumni. Men 20% or more over ideal weight-for-height were at 78% greater risk than lighter men. Those who had gained 25+ lbs (c. 11.5+ kg) since entering college were at 60% greater risk than those who had gained less. Alumni with a hypertensive parent were at 83% higher risk than men without such parentage. Contemporary vigorous exercise was inversely related to hypertension risk, but chiefly among alumni overweight-for-height. In the clinical sense, attributable risk estimates ranged from 30% to nearly 50% for the alumni characteristics of overweight, weight gain, parental hypertension, and lack of vigorous exercise. In the community sense, attributable risk of these same characteristics ranged 13-26%. To sum up, vigorous exercise is associated with lower hypertension incidence, and, without necessarily altering body weight-for-height, avoids or reduces fat and promotes muscle; obesity, rather than excess weight-for-height, is associated with higher hypertension incidence; hence, vigorous exercise is appropriate for use as an intervention regimen in the prevention of hypertension.

Diet, Physical Activity, and Colorectal Cancer Among Chinese in North America and China

Abstract: In a population-based case-control study of colorectal cancer among Chinese men and women in western North America and the People's Republic of China, a common protocol was used to assess past life-style characteristics of 905 cases diagnosed during 1981-1986 and 2,488 controls. Risks for cancers of both the colon and rectum increased with increased food energy from fat, protein, carbohydrate, and all energy sources combined, for both sexes and on both continents. Yet, in multivariate analysis, colorectal cancer risk was significantly associated only with saturated fat; no relationships were seen with other dietary sources of energy. Colon cancer risk was elevated among men employed in sedentary occupations. On both continents and in both sexes, risks for cancers of both the colon and rectum increased with increasing time spent sitting. Further, the association between colorectal cancer risk and saturated fat was stronger among the sedentary than among the active. Risk among sedentary Chinese Americans of either sex increased more than fourfold from the lowest to the highest category of saturated fat intake. Among migrants to North America, risk increased with increasing years lived in North America. These observations suggest (a) that colorectal cancer risk increases with duration of exposure to a sedentary life-style and a diet rich in saturated fat; (b) that higher incidence among Chinese-American men relative to women is due to longer duration of these habits among men, who have lived longer in North America; and (c) that higher risk among Chinese Americans of both sexes relative to risk among the general population in China is due to differences in such habits. Attributable risk calculations suggest that, if these associations are causal, saturated fat intakes exceeding 10 g/day, particularly in combination with physical inactivity, could account for 60% of colorectal cancer incidence among Chinese-American men and 40% among Chinese-American women.

Personal and environmental characteristics related to epithelial ovarian cancer. I. Reproductive and menstrual events and oral contraceptive use.

Abstract: In two case-control studies conducted in the six-county San Francisco Bay Area, 111 women diagnosed with epithelial ovarian carcinoma in 1974-1977 and 188 women diagnosed in 1983-1985 were interviewed concerning their menstrual, sexual, and reproductive histories. For comparison, interviews were conducted with 752 control women admitted to the same hospitals within six months of the cases; for cases diagnosed in the later period, interviews were also conducted with an additional 259 population-based controls selected by random digit dialing. Controls were matched to cases by age and race. Qualitative and quantitative findings were similar for the two studies. In the combined data, cases were more likely than their matched controls to have been nulliparous, to have undergone menarche at an early age, and to have refrained from using oral contraceptives. Menopause occurred slightly later for cases than for controls, but the differences were not statistically significant. Neither age at first term pregnancy (20 or more weeks gestation) nor number of term pregnancies was predictive of ovarian cancer risk. The protection afforded by oral contraceptive use was independent of parity, and it increased with increasing duration of use. There were no trends in risk with time since last oral contraceptive use or with time since first use, after adjustment for duration of use. These observations suggest that oral contraceptive use decreases risk for ovarian cancer, rather than merely indicates fertility, which may itself decrease risk of developing the disease. The authors combined reproductive characteristics and oral contraceptive use to estimate a woman's total duration of ovulation, which was positively associated with ovarian cancer risk (p less than 0.001 for trend). These observations support the concept that the greater the duration of ovulation or accompanying endocrinologic phenomena, the greater a woman's risk for ovarian cancer.

Physical activity and hypertension: an epidemiological view.

Abstract: We examined patterns of physical activity and other characteristics that might deter hypertension or delay all-cause mortality among university alumni, 1962–1985. Collegiate sports play did not alt...

Physical Activity and Public Health: A Recommendation From the Centers for Disease Control and Prevention and the American College of Sports Medicine

Abstract: Objective. —To encourage increased participation in physical activity among Americans of all ages by issuing a public health recommendation on the types and amounts of physical activity needed for health promotion and disease prevention. Participants. —A planning committee of five scientists was established by the Centers for Disease Control and Prevention and the American College of Sports Medicine to organize a workshop. This committee selected 15 other workshop discussants on the basis of their research expertise in issues related to the health implications of physical activity. Several relevant professional or scientific organizations and federal agencies also were represented. Evidence. —The panel of experts reviewed the pertinent physiological, epidemiologic, and clinical evidence, including primary research articles and recent review articles. Consensus Process. —Major issues related to physical activity and health were outlined, and selected members of the expert panel drafted sections of the paper from this outline. A draft manuscript was prepared by the planning committee and circulated to the full panel in advance of the 2-day workshop. During the workshop, each section of the manuscript was reviewed by the expert panel. Primary attention was given to achieving group consensus concerning the recommended types and amounts of physical activity. A concise "public health message" was developed to express the recommendations of the panel. During the ensuing months, the consensus statement was further reviewed and revised and was formally endorsed by both the Centers for Disease Control and Prevention and the American College of Sports Medicine. Conclusion. —Every US adult should accumulate 30 minutes or more of moderate-intensity physical activity on most, preferably all, days of the week. ( JAMA . 1995;273:402-407)

Physical Activity and Public Health Updated Recommendation for Adults From the American College of Sports Medicine and the American Heart Association

Abstract: Summary—In 1995 the American College of Sports Medicine and the Centers for Disease Control and Prevention published national guidelines on Physical Activity and Public Health The Committee on Exercise and Cardiac Rehabilitation of the American Heart Association endorsed and supported these recommendations The purpose of the present report is to update and clarify the 1995 recommendations on the types and amounts of physical activity needed by healthy adults to improve and maintain health Development of this document was by an expert panel of scientists, including physicians, epidemiologists, exercise scientists, and public health specialists This panel reviewed advances in pertinent physiologic, epidemiologic, and clinical scientific data, including primary research articles and reviews published since the original recommendation was issued in 1995 Issues considered by the panel included new scientific evidence relating physical activity to health, physical activity recommendations by various organizations in the interim, and communications issues Key points related to updating the physical activity recommendation were outlined and writing groups were formed A draft manuscript was prepared and circulated for review to the expert panel as well as to outside experts Comments were integrated into the final recommendation Primary Recommendation—To promote and maintain health, all healthy adults aged 18 to 65 yr need moderate-intensity aerobic (endurance) physical activity for a minimum of 30 min on five days each week or vigorous-intensity aerobic physical activity for a minimum of 20 min on three days each week [I (A)] Combinations of moderate- and vigorous-intensity activity can be performed to meet this recommendation [IIa (B)] For example, a person can meet the recommendation by walking briskly for 30 min twice during the week and then jogging for 20 min on two other days Moderate-intensity aerobic activity, which is generally equivalent to a brisk walk and noticeably accelerates the heart rate, can be accumulated toward the 30-min minimum by performing bouts each lasting 10 or more minutes [I (B)] Vigorous-intensity activity is exemplified by jogging, and causes rapid breathing and a substantial increase in heart rate In addition, every adult should perform activities that maintain or increase muscular strength and endurance a minimum of two days each week [IIa (A)] Because of the dose-response relation between physical activity and health, persons who wish to further improve their personal fitness, reduce their risk for chronic diseases and disabilities or prevent unhealthy weight gain may benefit by exceeding the minimum recommended amounts of physical activity [I (A)] (Circulation 2007;116:1081-1093)

Health benefits of physical activity: the evidence

Abstract: The primary purpose of this narrative review was to evaluate the current literature and to provide further insight into the role physical inactivity plays in the development of chronic disease and premature death. We confirm that there is irrefutable evidence of the effectiveness of regular physical activity in the primary and secondary prevention of several chronic diseases (e.g., cardiovascular disease, diabetes, cancer, hypertension, obesity, depression and osteoporosis) and premature death. We also reveal that the current Health Canada physical activity guidelines are sufficient to elicit health benefits, especially in previously sedentary people. There appears to be a linear relation between physical activity and health status, such that a further increase in physical activity and fitness will lead to additional improvements in health status.

Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association.

Abstract: Summary: In 1995 the American College of Sports Medicine and the Centers for Disease Control and Prevention published national guidelines on Physical Activity and Public Health. The Committee on Exercise and Cardiac Rehabilitation of the American Heart Association endorsed and supported these recommendations. The purpose of the present report is to update and clarify the 1995 recommendations on the types and amounts of physical activity needed by healthy adults to improve and maintain health. Development of this document was by an expert panel of scientists, including physicians, epidemiologists, exercise scientists, and public health specialists. This panel reviewed advances in pertinent physiologic, epidemiologic, and clinical scientific data, including primary research articles and reviews published since the original recommendation was issued in 1995. Issues considered by the panel included new scientific evidence relating physical activity to health, physical activity recommendations by various organizations in the interim, and communications issues. Key points related to updating the physical activity recommendation were outlined and writing groups were formed. A draft manuscript was prepared and circulated for review to the expert panel as well as to outside experts. Comments were integrated into the final recommendation. Primary Recommendation: To promote and maintain health, all healthy adults aged 18 to 65 yr need moderate-intensity aerobic (endurance) physical activity for a minimum of 30 min on five days each week or vigorous-intensity aerobic physical activity for a minimum of 20 min on three days each week. [I (A)] Combinations of moderate- and vigorous-intensity activity can be performed to meet this recommendation. [IIa (B)] For example, a person can meet the recommendation by walking briskly for 30 min twice during the week and then jogging for 20 min on two other days. Moderate-intensity aerobic activity, which is generally equivalent to a brisk walk and noticeably accelerates the heart rate, can be accumulated toward the 30-min minimum by performing bouts each lasting 10 or more minutes. [I (B)] Vigorous-intensity activity is exemplified by jogging, and causes rapid breathing and a substantial increase in heart rate. In addition, every adult should perform activities that maintain or increase muscular strength and endurance a minimum of two days each week. [IIa (A)] Because of the dose-response relation between physical activity and health, persons who wish to further improve their personal fitness, reduce their risk for chronic diseases and disabilities or prevent unhealthy weight gain may benefit by exceeding the minimum recommended amounts of physical activity. [I (A)]

Coronary Plaque Disruption

Abstract: Coronary atherosclerosis is by far the most frequent cause of ischemic heart disease, and plaque disruption with superimposed thrombosis is the main cause of the acute coronary syndromes of unstable angina, myocardial infarction, and sudden death.1 2 3 4 5 Therefore, for event-free survival, the vital question is not why atherosclerosis develops but rather why, after years of indolent growth, it suddenly becomes complicated by life-threatening thrombosis. The composition and vulnerability of plaque rather than its volume or the consequent severity of stenosis produced have emerged as being the most important determinants for the development of the thrombus-mediated acute coronary syndromes; lipid-rich and soft plaques are more dangerous than collagen-rich and hard plaques because they are more unstable and rupture-prone and highly thrombogenic after disruption.6 This review will explore potential mechanisms responsible for the sudden conversion of a stable atherosclerotic plaque to an unstable and life-threatening atherothrombotic lesion—an event known as plaque fissuring, rupture, or disruption.7 8 Atherosclerosis is the result of a complex interaction between blood elements, disturbed flow, and vessel wall abnormality, involving several pathological processes: inflammation, with increased endothelial permeability, endothelial activation, and monocyte recruitment9 10 11 12 13 14 ; growth, with smooth muscle cell (SMC) proliferation, migration, and matrix synthesis15 16 ; degeneration, with lipid accumulation17 18 ; necrosis, possibly related to the cytotoxic effect of oxidized lipid19 ; calcification/ossification, which may represent an active rather than a dystrophic process20 21 ; and thrombosis, with platelet recruitment and fibrin formation.1 22 23 Thrombotic factors may play a role early during atherogenesis, but a flow-limiting thrombus does not develop until mature plaques are present, which is why thrombosis often is classified as a complication rather than a genuine component of atherosclerosis. ### Mature Plaques: Atherosis and Sclerosis As the name atherosclerosis implies, mature …