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Biomedical subjects

I M Lee

Publications and source records attributed to I M Lee.

At least 37 records · Page 2Linked to original sources
PubMed2000

Triggering of sudden death from cardiac causes by vigorous exertion.

BACKGROUND: Retrospective and cross-sectional data suggest that vigorous exertion can trigger cardiac arrest or sudden death and that habitual exercise may diminish this risk. However, the role of physical activity in precipitating or preventing sudden death has not been assessed prospectively in a large number of subjects. METHODS: We used a prospective, nested case-crossover design within the Physicians' Health Study to compare the risk of sudden death during and up to 30 minutes after an episode of vigorous exertion with that during periods of lighter exertion or none. We then evaluated whether habitual vigorous exercise modified the risk of sudden death that was associated with vigorous exertion. In addition, the relation of vigorous exercise to the overall risk of sudden death and nonsudden death from coronary heart disease was assessed. RESULTS: During 12 years of follow-up, 122 sudden deaths were confirmed among the 21,481 male physicians who were initially free of self-reported cardiovascular disease and who provided information on their habitual level of exercise at base line. The relative risk of-sudden death during and up to 30 minutes after vigorous exertion was 16.9 (95 percent confidence interval, 10.5 to 27.0; P<0.001). However, the absolute risk of sudden death during any particular episode of vigorous exertion was extremely low (1 sudden death per 1.51 million episodes of exertion). Habitual vigorous exercise attenuated the relative risk of sudden death that was associated with an episode of vigorous exertion (P value for trend=0.006). The base-line level of exercise was not associated with the overall risk of subsequent sudden death. CONCLUSIONS: These prospective data from a study of U.S. male physicians suggest that habitual vigorous exercise diminishes the risk of sudden death during vigorous exertion.

Adult↗
PubMed2000

Physical activity and coronary heart disease in men: The Harvard Alumni Health Study.

BACKGROUND: The quantity and intensity of physical activity required for the primary prevention of coronary heart disease (CHD) remain unclear. Therefore, we examined the association of the quantity and intensity of physical activity with CHD risk and the impact of other coronary risk factors. METHODS AND RESULTS: We followed 12 516 middle-aged and older men (mean age 57.7 years, range 39 to 88 years) from 1977 through 1993. Physical activity was assessed at baseline in kilojoules per week (4.2 kJ=1 kcal) from blocks walked, flights climbed, and participation in sports or recreational activities. During follow-up, 2,135 cases of incident CHD, including myocardial infarction, angina pectoris, revascularization, and coronary death, occurred. Compared with men expending <2,100 kJ/wk, men expending 2,100 to 4,199, 4,200 to 8,399, 8,400 to 12,599, and >/=12,600 kJ/wk had multivariate relative risks of 0.90, 0.81, 0.80, and 0.81, respectively (P: for trend=0.003). When we considered the independent effects of specific physical activity components, only total sports or recreational activities (P: for trend=0.042) and vigorous activities (P: for trend=0.02) were inversely associated with the risk of CHD. These associations did not differ within subgroups of men defined by coronary risk factors. Finally, among men with multiple coronary risk factors, those expending >/=4,200 kJ/wk had reduced CHD risk compared with men expending <4,200 kJ/wk. CONCLUSIONS: Total physical activity and vigorous activities showed the strongest reductions in CHD risk. Moderate and light activities, which may be less precisely measured, showed nonsignificant inverse associations. The association between physical activity and a reduced risk of CHD also extends to men with multiple coronary risk factors.

Adult↗
PubMed2000

Physical activity and coronary heart disease risk in men: does the duration of exercise episodes predict risk?

BACKGROUND: Physical activity is associated with a decreased risk of coronary heart disease (CHD). However, it is unclear whether the duration of exercise episodes is important: Are accumulated shorter sessions as predictive of decreased risk as longer sessions if the same amount of energy is expended? METHODS AND RESULTS: In the Harvard Alumni Health Study, we prospectively followed 7307 Harvard University alumni (mean age 66.1 years) from 1988 through 1993. At baseline, men reported their walking, stair climbing, and participation in sports or recreational activities. For each of the latter activities, they also reported the frequency and average duration per episode. During follow-up, 482 men developed CHD. In age-adjusted analysis, a longer duration of exercise episodes predicted lower CHD risk (P: trend=0.04). However, after total energy expended on physical activity and potential confounders was accounted for, duration no longer had an independent effect on CHD risk (P: trend=0.25); that is, longer sessions of exercise did not have a different effect on risk compared with shorter sessions, as long as the total energy expended was similar. In contrast, higher levels of total energy expenditure significantly predicted decreased CHD risk in both age-adjusted (P: trend=0.009) and multivariate (P: trend=0.046) analyses. CONCLUSIONS: These data clearly indicate that physical activity is associated with decreased CHD risk. Furthermore, they lend some support to recent recommendations that allow for the accumulation of shorter sessions of physical activity, as opposed to requiring 1 longer, continuous session of exercise. This may provide some impetus for those sedentary to become more active.

Aged↗
PubMed2000

Comparison of National Death Index and World Wide Web death searches.

The authors used the National Death Index and a World Wide Web Internet site that searches the Social Security Administration master files of deaths to determine the mortality status of 1,000 US subjects from the College Alumni Health Study. Subjects were classified as definitely dead, possibly dead, or presumed alive. Of 246 definite deaths pinpointed by the National Death Index, the World Wide Web identified 94.7% of them. Of 438 men presumed alive according to the National Death Index, the World Wide Web identified 97.5% of them. However, the World Wide Web was not useful for identifying deaths of women. This study demonstrated that the World Wide Web may provide an alternative, inexpensive method of determining the mortality status of subjects in relatively small epidemiologic studies.

Databases, Factual↗
PubMed2000

Cigarette smoking and risk of prostate cancer in the physicians' health study (United States).

To assess whether cigarette smoking is associated with prostate cancer incidence or mortality, we analyzed a large cohort of 22,071 men, aged 40-84 at baseline, in the Physicians' Health Study. During an average of 12.5 years of follow-up, we documented 996 cases of prostate cancer, including 113 fatal cases. Men were categorized according to smoking status, total pack-years smoked, and duration of smoking. We used Cox proportional hazard models to estimate the relative risks associated with smoking. Compared to never smokers, the age-adjusted relative risks (RR) of total prostate cancer were 1. 14 (95% confidence interval [CI] = 1.00-1.30) for past smokers, 1.10 (95% CI = 0.78-1.55) for current smokers of less than 20 cigarettes per day, and 1.10 (95% CI = 0.84-1.44) for current smokers of 20 or more cigarettes per day. Adjustment for body mass index, height, alcohol intake, and physical activity did not materially alter these findings. No significant association was observed in analyses of total pack-years smoked or duration of smoking. The results were similar for non-fatal and fatal prostate cancer. These data indicate no material association between cigarette smoking and prostate cancer incidence or mortality.

Adult↗
PubMed2000

Associations of light, moderate, and vigorous intensity physical activity with longevity. The Harvard Alumni Health Study.

Physical activity is associated with better health; however, the optimal intensity of activity remains unclear. A total of 13,485 men (mean age, 57.5 years) from the Harvard Alumni Health Study reported their walking, stair climbing, and sports/recreation in 1977. Between 1977 and 1992, 2,539 died. After adjusting for the different activity components, distance walked and storeys climbed independently predicted longevity (p, trend = 0.004 and <0.001, respectively). Light activities (<4 multiples of resting metabolic rate (METs)) were not associated with reduced mortality rates, moderate activities (4-<6 METs) appeared somewhat beneficial, and vigorous activities (> or =6 METs) clearly predicted lower mortality rates (p, trend = 0.72, 0.07, and <0.001, respectively). These data provide some support for current recommendations that emphasize moderate intensity activity; they also clearly indicate a benefit of vigorous activity.

Aged↗
PubMed2000

Fruit and vegetable intake and risk of cardiovascular disease: the Women's Health Study.

BACKGROUND: Prospective data relating fruit and vegetable intake to cardiovascular disease (CVD) risk are sparse, particularly for women. OBJECTIVE: In a large, prospective cohort of women, we examined the hypothesis that higher fruit and vegetable intake reduces CVD risk. DESIGN: In 1993 we assessed fruit and vegetable intake among 39876 female health professionals with no previous history of CVD or cancer by use of a detailed food-frequency questionnaire. We subsequently followed these women for an average of 5 y for incidence of nonfatal myocardial infarction (MI), stroke, percutaneous transluminal coronary angioplasty, coronary artery bypass graft, or death due to CVD. RESULTS: During 195647 person-years of follow-up, we documented 418 incident cases of CVD including 126 MIs. After adjustment for age, randomized treatment status, and smoking, we observed a significant inverse association between fruit and vegetable intake and CVD risk. For increasing quintiles of total fruit and vegetable intake (median servings/d: 2. 6, 4.1, 5.5, 7.1, and 10.2), the corresponding relative risks (RRs) were 1.0 (reference), 0.78, 0.72, 0.68, and 0.68 (95% CI comparing the 2 extreme quintiles: 0.51, 0.92; P: for trend = 0.01). An inverse, though not statistically significant, trend remained after additional adjustment for other known CVD risk factors, with RRs of 1.0, 0.75, 0.83, 0.80, and 0.85 (95% CI for extreme quintiles: 0.61, 1.17). After excluding participants with a self-reported history of diabetes, hypertension, or high cholesterol at baseline, the multivariate-adjusted RR was 0.45 when extreme quintiles were compared (95% CI: 0.22, 0.91; P: for trend = 0.09). Higher fruit and vegetable intake was also associated with a lower risk of MI, with an adjusted RR of 0.62 for extreme quintiles (95% CI: 0.37, 1.04; P: for trend = 0.07). CONCLUSION: These data suggest that higher intake of fruit and vegetables may be protective against CVD and support current dietary guidelines to increase fruit and vegetable intake.

Age Factors↗
PubMed2000

A prospective study of physical activity and risk of prostate cancer in US physicians.

BACKGROUND: Exercise can suppress androgen production and may thus decrease the risk of prostate cancer. However, findings from epidemiological studies assessing physical activity and risk of prostate cancer are inconsistent. METHODS: We prospectively examined the association between physical activity and prostate cancer risk in the Physicians' Health Study (PHS), a randomized trial of low-dose aspirin and beta-carotene among 22,071 men aged 40-84 without self-reported myocardial infarction, stroke and cancer. At baseline in 1982, men were asked about the frequency of exercise vigorous enough to work up a sweat. Physical activity was assessed in a similar fashion again at 36 months of follow-up. RESULTS: During 11.1 years of follow-up (258 779 person-years), 982 cases of prostate cancer occurred and were confirmed by medical record review. After adjustment for potential confounding factors (including age, height, randomized treatment assignment, smoking status, alcohol intake, use of multivitamins, history of diabetes, history of hypertension and history of high cholesterol), the relative risks for prostate cancer associated with exercise vigorous enough to work up a sweat were 1.0 (referent) for frequency less than once per week, 1.02 (95% CI: 0.82-1.26) for once per week, 1.07 (95% CI: 0.90-1.27) for 2-4 times per week, and 1.11 (95% CI: 0.90-1.36) for 5+ times per week. Across all subgroups of men categorized by age, body mass index, smoking status, alcohol intake, use of multivitamins, history of diabetes, history of hypertension and history of high cholesterol, there were no significant associations between frequency of exercise vigorous enough to work up a sweat and prostate cancer risk. After excluding cases of prostate cancer that occurred during the first 36 months of follow-up, again, there was no significant association. Combining physical activity assessments at baseline and at 36 months also yielded no significant association with prostate cancer risk. CONCLUSIONS: These observational data from the Physicians' Health Study do not support the hypothesis that increased physical activity reduces the risk of prostate cancer.

Adult↗
PubMed2000

Classification of aster yellows-group phytoplasmas based on combined analyses of rRNA and tuf gene sequences.

Seventy phytoplasma isolates, including 10 previously characterized reference strains, of the aster yellows group were examined by RFLP analysis of PCR-amplified rDNA and RFLP and sequence analysis of the tuf gene. On the basis of rDNA restriction profiles, seven previously proposed 16S rDNA subgroups (16SrI-A, -B, -C, -D, -E, -F and -K) were recognized in the material examined. In addition, three new subgroups that differ in the RFLP profiles were identified and designated 16SrI-L, 16SrI-M and 16SrI-N. Of the two types of rDNA sequences used, an 1800 bp fragment comprising the entire 16S rRNA gene and the 16S-23S rDNA spacer region proved more suitable for AY-group phytoplasma differentiation than a 1240 bp fragment of the 16S rRNA gene. Many differences in the rDNA profiles between the subgroups could be explained by sequence heterogeneity of the two phytoplasmal rRNA operons. The subgroups delineated by RFLP analysis of a 940 bp tuf gene fragment are consistent with subgroups defined on the basis of rDNA sequences. However, subgroups 16SrI-D, -L and -M showed the same tuf gene restriction profiles as subgroup 16SrI-B. This result was confirmed by sequence analysis in which these subgroups differed slightly in their tuf gene sequence, when compared with members of subgroup 16SrI-B. On the basis of combined analyses of rDNA and tuf gene sequences and in view of pathological aspects, the taxonomic distinction of AY-subgroups 16SrI-A, -B, -C, -D, -E, -F, -K and -N appears to be substantial.

Acholeplasmataceae↗
PubMed2000

Phytoplasma: phytopathogenic mollicutes.

During the past decade, research has yielded new knowledge about the plant and insect host ranges, geographical distribution, and phylogenetic relationships of phytoplasmas, and a taxonomic system has emerged in which distinct phytoplasmas are named as separate "Candidatus phytoplasma species." In large part, this progress has resulted from the development and use of molecular methods to detect, identify, and classify phytoplasmas. While these advances continue, research has recently begun on the phytoplasma genome, how phytoplasmas cause disease, the role of mixed phytoplasmal infections in plant diseases, and molecular/genetic phenomena that underlie symptom development in plants. These and other recent advances are laying the foundation for future progress in understanding the mechanisms of phytoplasma pathogenicity, organization of the phytoplasma genome, evolution of new phytoplasma strains and emergence of new diseases, bases of insect transmissibility and specificity of transmission, and plant gene expression in response to phytoplasmal infection, as well as the design of novel approaches to achieve effective control of phytoplasmal diseases.

Ecology↗
PubMed1999

Sense of exhaustion and coronary heart disease among college alumni.

Vital exhaustion, defined as a combination of fatigue, lack of energy, feelings of hopelessness, loss of libido, and increased irritability, has been proposed as a risk indicator for the development of coronary heart disease (CHD). It is unclear if the association between vital exhaustion and CHD is independent of sleep behavior, depression, and physical activity. We ascertained sense of exhaustion among 5,053 male college alumni who were free of cardiovascular disease, cancer, and chronic obstructive pulmonary disease by asking, "How often do you experience sense of exhaustion (except after exercise)?" on a health survey in 1980. Eight hundred fifteen men died during 12 years of follow-up, 25% due to CHD. After adjustment for age, body mass index, smoking status, and history of physician-diagnosed diabetes and hypertension, frequent sense of exhaustion was associated with a twofold increase in CHD mortality (rate ratio 2.07; 95% confidence interval 1.08 to 3.96). After additional adjustment for insomnia, sleep duration, use of sleeping pills and tranquilizers, physical activity, history of physician-diagnosed depression, and alcohol intake, the rate ratio was not appreciably altered; however, the association now was of borderline significance (rate ratio 2.06; 95% confidence interval: 0.98 to 4.36) because there were only 10 deaths from CHD among men who were frequently exhausted. In a prospective observational study, frequent sense of exhaustion appeared to be independently associated with increased risk of CHD mortality in men.

Adult↗
PubMed1999

Beta-carotene supplementation and incidence of cancer and cardiovascular disease: the Women's Health Study.

BACKGROUND: In observational studies, individuals with high intakes of fruits and vegetables containing beta-carotene experience lower risks of developing cancer. However, the few randomized trials of beta-carotene supplementation show no overall benefits; some even suggest harm. This trial was designed to test the effects of beta-carotene supplementation in women. METHODS: The Women's Health Study is a randomized, double-blind, placebo-controlled trial originally testing aspirin, vitamin E, and beta-carotene in the prevention of cancer and cardiovascular disease among 39 876 women aged 45 years or older. The beta-carotene component was terminated early after a median treatment duration of 2.1 years (range = 0.00-2. 72 years). Statistical tests were two-sided. RESULTS: Among women randomly assigned to receive beta-carotene (50 mg on alternate days; n = 19 939) or placebo (n =19 937), there were no statistically significant differences in incidence of cancer, cardiovascular disease, or total mortality after a median of 4.1 years (2.1 years' treatment plus another 2.0 years' follow-up). There were 378 cancers in the beta-carotene group and 369 cancers in the placebo group (relative risk [RR] = 1.03; 95% confidence interval [CI] = 0.89-1. 18). There were no statistically significant differences for any site-specific cancer or during years 1 and 2 combined and years 3 and up combined. For cardiovascular disease, there were no statistically significant differences for myocardial infarction (42 in the beta-carotene group versus 50 in the placebo group), stroke (61 versus 43), deaths from cardiovascular causes (14 versus 12), or the combined end point of these three events (116 versus 102; among women with more than one event, only the first was counted). Deaths from any cause were similar in the two groups (59 versus 55). Among smokers at baseline (13% of all women), there were no statistically significant differences in overall incidence of cancer (RR = 1.11; 95% CI = 0.78-1.58) or cardiovascular disease (RR = 1.01; 95% CI = 0. 62-1.63). CONCLUSION: Among apparently healthy women, there was no benefit or harm from beta-carotene supplementation for a limited period on the incidence of cancer and of cardiovascular disease.

Aged↗
PubMed1999

Comparison of self-reported diagnosis of connective tissue disease with medical records in female health professionals: the Women's Health Cohort Study.

To compare self-report of connective tissue disease (CTD) with medical records, subjects were selected from 395,543 female health professionals with and without breast implants who reported CTD on mailed questionnaires from 1992 to 1995. The authors identified 220 women with breast implants (exposed) who self-reported CTD and a random sample of 879 women without breast implants (unexposed) who also self-reported CTD, matched by age and date of diagnosis. Medical records were reviewed using classification criteria from the American College of Rheumatology or other published criteria. After up to three requests and a telephone call, 27.7% of the women provided consent for medical record review. Exposed women appeared somewhat more likely (33.2% vs. 26.3%, p = 0.04) to provide consent. Using medical record reviews for 90% of the women who provided consent, confirmation rates of definite CTD were similar among the exposed and unexposed (22.7% vs. 24.0%, p = 0.83). This study demonstrates the difficulty of obtaining consent for medical record review of CTD reported to have occurred years ago in women with and without breast implants. Confirmation rates were low but were similar in exposed and unexposed. Despite the fact that the study had low participation rates, the data suggest that relative risk estimates for any definite CTD among women with breast implants compared with women without breast implants would be similar in analyses of self-reported or medical record-confirmed cases.

Adult↗
PubMed1999

Physical activity and cardiovascular disease risk in middle-aged and older women.

The authors investigated the relation between physical activity and cardiovascular disease (CVD) in women by following 1,564 University of Pennsylvania alumnae (mean age, 45.5 years), initially free of CVD, from 1962 until 1993. Energy expenditure was estimated from the daily number of flights of stairs climbed and blocks walked as well as the sports played and was categorized into approximate thirds (<500, 500-999, > or = 1,000 kcal/week). During 35,021 person-years, 181 CVD cases were identified. After adjustment for coronary risk factors, the relative risks of CVD were 0.99 (95% confidence interval (CI): 0.69, 1.41) and 0.88 (95% CI: 0.62, 1.25) for women who expended 500-999 and > or = 1,000, respectively, compared with <500 kcal/week (p for trend = 0.45). Only walking was found to be inversely related to CVD risk (p for trend = 0.054). Compared with women who walked <4 blocks/day, the relative risks of CVD were 0.84 (95% CI: 0.59, 1.19) and 0.67 (95% CI: 0.45, 1.01) for women who walked 4-9 and > or = 10 blocks/day, respectively. Finally, an interaction (p = 0.023) between body mass index and physical activity on CVD risk was observed, with an inverse association only for leaner (<23 kg/m2) women. These data showed no overall association of physical activity with CVD risk in women. However, walking > or = 10 blocks/day (approximately 6 miles (9.7 km)/week) was associated with a 33% decreased risk. One explanation for this finding may be that walking was reported more precisely than other kinds of activities.

Aged↗
PubMed1999

A retrospective cohort study of cigarette smoking and risk of rheumatoid arthritis in female health professionals.

OBJECTIVE: To study the association of cigarette smoking with risk of rheumatoid arthritis (RA), among 377,481 female health professionals in the Women's Health Cohort Study. METHODS: Subjects completed mailed questionnaires regarding demographics, health habits, including cigarette smoking history, and medical history, including RA diagnosis made by a physician and date of diagnosis. Of 7,697 women who self-reported RA, 3,416 reported seropositive RA. Cox proportional hazards regression models were used to retrospectively assess the associations of smoking intensity and duration with the risk of developing RA or seropositive RA. Cigarette smoking status was treated as a time-varying exposure in these regression models. RESULTS: In multivariate analyses controlling for age, race, education, age at menarche, pregnancy history, menopausal status, and postmenopausal hormone use, duration of smoking was associated with a significantly increased risk of both RA and seropositive RA (both P < 0.01 for trend), after adjusting for smoking intensity. Women who smoked > or =25 cigarettes/day for more than 20 years experienced a 39% increased risk of RA and 49% increased risk of seropositive RA. However, smoking intensity (number of cigarettes/day) was unrelated to risk of RA or seropositive RA (both P = 0.3 for trend), after adjusting for duration of smoking. CONCLUSION: Duration, but not intensity, of cigarette smoking is associated with a modest increased risk of RA in women.

Arthritis, Rheumatoid↗
PubMed1999

Physical activity and risk of lung cancer.

BACKGROUND: Physical activity has been proposed to decrease lung cancer risk; however, few data are available. Further, no studies have examined specific kinds and intensities of activities. METHODS: We conducted a prospective cohort study among 13 905 male Harvard University alumni (mean age, 58.3 years), free of cancer. Men reported their walking, stair climbing and participation in sports or recreation on baseline questionnaires in 1977, and the occurrence of lung cancer on follow-up questionnaires in 1988 and 1993. Death certificates were obtained for decedents through 1992 to determine lung cancers not previously reported. RESULTS: During follow-up, 245 men developed lung cancer. Adjusting for age, cigarette smoking, and body mass index, the relative risks of lung cancer associated with <4200, 4200-8399, 8400-12 599 and > or =12 600 kJ/week of estimated energy expenditure at baseline were 1.00 (referent), 0.87 (95% CI: 0.64-1.18), 0.76 (95% CI: 0.52-1.11), and 0.61 (95% CI: 0.41-0.89), respectively; P trend = 0.0008. Similar trends were observed among non-smokers or former smokers in 1977 (82.7% of men) as well as among those who smoked >20 cigarettes a day in 1977 (8.0%), although the findings in the latter group were not statistically significant, possibly due to the small number. Walking, climbing stairs and participating in activities of at least moderate intensity (> or =4.5 MET, or multiples of resting metabolic rate) were each inversely associated with lung cancer risk, independent of the other activity components. However, light intensity activities (<4.5 MET) did not predict lung cancer risk. CONCLUSIONS: These data indicate that physical activity may be associated with lower risk of lung cancer among men. An energy expenditure of 12 600 kJ/week, achievable by perhaps 6-8 hours of at least moderate intensity physical activity, may significantly lower risk. Further studies are required to confirm these observations.

Death Certificates↗