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Biomedical subjects

I M Lee

Publications and source records attributed to I M Lee.

At least 19 recordsLinked to original sources
PubMed2004

Inactivation of indicator micro-organisms from various sources of faecal contamination in seawater and freshwater.

AIM: The survival of indicator micro-organisms in aquatic systems is affected by both biotic and abiotic factors. Much of the past research on this topic has been conducted using laboratory-generated cultures of indicator bacteria. For this study, we used natural sources of faecal contamination as inoculants into environmental water samples, thereby representing the wide diversity of organisms likely to be found in faecal contamination. METHODS AND RESULTS: Rates of inactivation of water quality indicators, total coliforms (TC), Escherichia coli, enterococci (EC) and F+-specific coliphage were studied in three experiments using inoculants of sewage influent, sewage effluent and urban storm drain run-off. Effects of temperature, nutrients, total suspended solids, bacterial load and solar irradiation were studied in fresh and seawater matrices. Results demonstrated that temperature and solar irradiation had significant effects upon rates of inactivation (anova, P < 0.001). Inactivation rates were similar, regardless of the inoculant type. EC degraded the slowest in the dark with T90s of 115-121 and 144-177 h at 20 and 14 degrees C, respectively. When incubated in sunlight, EC was inactivated significantly more rapidly than either E. coli or F+-specific coliphage (P < 0.001). CONCLUSIONS: Inactivation of indicator bacteria is not dependent upon the original source of contamination. Inactivation rates of indicator bacteria were similar in fresh and seawater matrices. However, EC degraded more rapidly in sunlight than E. coli. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that the source of faecal contamination is not an important factor to inactivation rates of indicator bacteria. However, rates of inactivation of indicator bacteria are likely system specific.

Coliphages↗
PubMed2002

The palliative benefit of irinotecan in 5-fluorouracil-refractory colorectal cancer: its prospective evaluation by a Multicenter Canadian Trial.

Most patients with colorectal cancer (CRC) who have failed initial 5-fluorouracil (5-FU) chemotherapy have worsening of disease-related symptoms (DRS) and quality of life (QOL). Irinotecan has a reported response rate of 10%-20% in such patients. The aim of this phase II trial was to prospectively determine the palliative benefit of irinotecan utilizing DRS as primary endpoints of response. Patients had advanced CRC refractory to 5-FU with at least 1 DRS defined as (1) Karnofsky performance status (KPS) 60%-80%, (2) baseline analgesic use > or = 10 mg morphine/day (or equivalent), or (3) disease-related pain score > 1 cm on a 10-cm linear analogue self-assessment (LASA) scale. Patients received irinotecan 125 mg/m2 weekly for 4 weeks on an every-6-weeks schedule. The primary endpoint was palliative response defined as > or = 50% decrease in pain score or analgesic usage, or 10% increase in KPS, from baseline for 4 weeks. QOL was assessed by the European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire Core 30 (EORTC QLQ-C30) version 2 instrument. A total of 65 patients were entered onto the study. Median baseline parameters were KPS 70%, analgesic score 11 mg/day, and pain score 2.4 cm. A palliative response was achieved in 27 patients (42%), improvement in pain score predominated. LASA and EORTC QLQ-C30 instruments showed parallel changes in DRS. The radiological response rate was 11% (complete responses and partial responses, n = 46); 23 patients achieved stable disease. Median overall survival was 7.2 months. Irinotecan provides a rate of palliative benefit higher than the radiological response rate. Patients-oriented palliative endpoints can be useful in assessing the benefit of agents in early-phase clinical trials.

Adult↗
PubMed2001

Lifetime physical activity and risk of breast cancer.

We conducted a case-control study of 394 women with breast cancer and 788 control women (91% response) to investigate the association of lifetime physical activity with mainly menopausal breast cancer risk. After controlling for potential confounders, the odds ratios (95% confidence intervals) for increasing quartiles of lifetime physical activity were 1.00 (referent), 0.91 (0.60-1.37), 0.91 (0.60-1.39), and 1.10 (0.73-1.67), respectively; P, trend = 0.47. We also separately examined physical activity at ages 12-18, 19-34, 35-49 and > or =50 years; no significant trends were observed in any age group. These data do not support a role of physical activity in preventing breast cancer.

Adolescent↗
PubMed2001

Maternal and paternal history of myocardial infarction and risk of cardiovascular disease in men and women.

BACKGROUND: Few studies have examined the effects of paternal and maternal history of myocardial infarction (MI), including age at MI, on cardiovascular disease (CVD) risk, particularly among women. METHODS AND RESULTS: We prospectively studied 22 071 men from the Physicians' Health Study and 39 876 women from the Women's Health Study with data on parental history and age at MI. Among men, 2654 CVD cases developed over 13.0 years; among women, 563 CVD cases occurred over 6.2 years. Compared with men with no parental history, only maternal, only paternal, and both maternal and paternal history of MI conferred relative risks (RRs) of CVD of 1.71, 1.40, and 1.85; among women, the respective RRs were 1.46, 1.15, and 2.05. For men, maternal age at MI of <50, 50 to 59, 60 to 69, 70 to 79, and >/=80 years had RRs of 1.00, 1.88, 1.88, 1.67, and 1.17; for women, the RRs for maternal age at MI of <50, 50 to 59, and >/=60 years were 2.57, 1.33, and 1.52. Paternal age at MI of <50, 50 to 59, 60 to 69, 70 to 79, and >/=80 years in men had RRs of 2.19, 1.64, 1.42, 1.16, and 0.92; in women, for paternal age at MI of <50, 50 to 59, and >/=60 years, the RRs were 1.63, 1.33, and 1.13. CONCLUSIONS: An early history of parental MI (<60 years) conferred a greater risk of CVD than did MI at older ages. However, an increased risk of CVD remained for maternal age at MI of 70 to 79 years in men and >/=60 years in women, which suggests that any maternal history of MI may be important.

Adult↗
PubMed2001

Physical activity and coronary heart disease in women: is "no pain, no gain" passé?

CONTEXT: Physically active women have lower coronary heart disease (CHD) rates than inactive women. However, whether the association differs by intensity of activity or in women at high risk for CHD is unclear. OBJECTIVE: To examine the relation between physical activity, specifically investigating walking (a light-to-moderate activity depending on pace), and CHD among women, including those at high risk for CHD. DESIGN, SETTING, AND PARTICIPANTS: Cohort study of 39 372 healthy female health professionals aged 45 years or older, enrolled throughout the United States between September 1992 and May 1995, with follow-up to March 1999. Recreational activities, including walking and stair climbing, were reported at study entry. MAIN OUTCOME MEASURE: Correlation of CHD with energy expended on all activities, vigorous activities, and walking. RESULTS: A total of 244 cases of CHD occurred. Adjusting for potential confounders, the relative risks (RRs) of CHD for less than 200, 200-599, 600-1499, and 1500 or more kcal/wk expended on all activities were 1.00 (referent), 0.79 (95% confidence interval [CI], 0.56-1.12), 0.55 (95% CI, 0.37-0.82), and 0.75 (95% CI, 0.50-1.12), respectively (P for linear trend =.03). Vigorous activities were associated with lower risk (RR, 0.63; 95% CI, 0.38-1.04 comparing highest and lowest categories). Walking also predicted lower risk among women without vigorous activities. Among these women, the multivariate RRs for walking 1 to 59 min/wk, 1.0 to 1.5 h/wk, and 2 or more h/wk, compared with no regular walking, were 0.86 (95% CI, 0.57-1.29), 0.49 (95% CI, 0.28-0.86), and 0.48 (95% CI, 0.29-0.78), respectively. For walking paces of less than 3.2 km/h (2.0 mph), 3.2 to 4.7 km/h (2.0-2.9 mph), and 4.8 km/h (3.0 mph) or more, compared with no regular walking, RRs were 0.56 (95% CI, 0.32-0.97), 0.71 (95% CI, 0.47-1.05), and 0.52 (95% CI, 0.30-0.90), respectively. When analyzed simultaneously, time spent walking (P for linear trend =.01) but not walking pace (P for linear trend =.55) predicted lower risk. The inverse association between physical activity and CHD risk did not differ by weight or cholesterol levels (P for interaction =.95 and.71, respectively), but there were significant interactions by smoking and hypertension status. Physical activity was inversely related to risk in current smokers but not hypertensive women (P for interaction =.01 and.001, respectively). CONCLUSIONS: These data indicate that even light-to-moderate activity is associated with lower CHD rates in women. At least 1 hour of walking per week predicted lower risk. The inverse association with physical activity was also present in women at high risk for CHD, including those who were overweight, had increased cholesterol levels, or were smokers.

Cohort Studies↗
PubMed2001

Long-term weight loss and changes in blood pressure: results of the Trials of Hypertension Prevention, phase II.

BACKGROUND: Weight loss appears to be an effective method for primary prevention of hypertension. However, the long-term effects of weight loss on blood pressure have not been extensively studied. OBJECTIVE: To present detailed results from the weight loss arm of Trials of Hypertension Prevention (TOHP) II. DESIGN: Multicenter, randomized dinical trial testing the efficacy of lifestyle interventions for reducing blood pressure over 3 to 4 years. Participants in TOHP II were randomly assigned to one of four groups. This report focuses only on participants assigned to the weight loss (n = 595) and usual care control (n = 596) groups. PATIENTS: Men and women 30 to 54 years of age who had nonmedicated diastolic blood pressure of 83 to 89 mm Hg and systolic blood pressure less than 140 mm Hg and were 110% to 165% of their ideal body weight at baseline. INTERVENTION: The weight loss intervention included a 3-year program of group meetings and individual counseling focused on dietary change, physical activity, and social support MEASUREMENTS: Weight and blood pressure data were collected every 6 months by staff who were blinded to treatment assignment RESULTS: Mean weight change from baseline in the intervention group was -4.4 kg at 6 months, -2.0 kg at 18 months, and -0.2 kg at 36 months. Mean weight change in the control group at the same time points was 0.1, 0.7, and 1.8 kg. Blood pressure was significantly lower in the intervention group than in the control group at 6, 18, and 36 months. The risk ratio for hypertension in the intervention group was 0.58 (95% CI, 0.36 to 0.94) at 6 months, 0.78 (CI, 0.62 to 1.00) at 18 months, and 0.81 (CI, 0.70 to 0.95) at 36 months. In subgroup analyses, intervention participants who lost at least 4.5 kg at 6 months and maintained this weight reduction for the next 30 months had the greatest reduction in blood pressure and a relative risk for hypertension of 0.35 (CI, 0.20 to 0.59). CONCLUSIONS: Clinically significant long-term reductions in blood pressure and reduced risk for hypertension can be achieved with even modest weight loss.

Adult↗
PubMed2001

Active and passive smoking and risk of colds in women.

PURPOSE: To evaluate the association between active and passive smoking and frequency of colds in women. METHODS: Data on cigarette smoking and frequency and duration of colds were analyzed in the Women's Health Study (WHS), a randomized, double-blind, placebo-controlled trial of low-dose aspirin and vitamin E in the primary prevention of cardiovascular disease and cancer among 39,876 female health professionals. RESULTS: After adjustment for age, body-mass index, prevalence of asthma and chronic lung diseases, alcohol intake, physical activity, and multivitamin use, current heavy smokers had no appreciable increase in the frequency of colds (relative risk (RR) for >or= 3 versus no colds in the past year, 1.05; 95% confidence interval (CI), 0.80-1.39), but a significantly increased risk of prolonged colds (RR for colds of > 7 vs. 1-3 days, 2.53; 95% CI, 1.95-3.29). There was no difference in the number of days confined to home. Nonsmoking women passively exposed to cigarette smoke had a slightly increased risk of both more frequent colds (RR, 1.33; 95% CI, 1.18-1.51) and more prolonged colds during the previous year (RR, 1.12; 95% CI, 0.99-1.27). CONCLUSIONS: Women who are currently heavy smokers are at increased risk of having colds with longer duration compared with nonsmokers. Nonsmoking women passively exposed to cigarette smoking are at slightly increased risk of having more frequent and longer colds than nonsmoking women not exposed to passive smoke.

Common Cold↗
PubMed2001

Physical activity and breast cancer risk: the Women's Health Study (United States).

OBJECTIVE: It is biologically plausible for physical activity to decrease breast cancer risk; however, epidemiologic studies have yielded inconsistent findings. We therefore examined physical activity and breast cancer risk in the Women's Health Study. METHODS: We assessed physical activity among 39,322 apparently healthy women, aged > or = 45 years, and prospectively followed them for an average of 48 months. Four hundred eleven women developed breast cancer, with 222 positive for both estrogen and progesterone receptors. RESULTS: Among all women the multivariate relative risks of all breast cancer associated with < 840, 840-2519, 2520-6299, and > or = 6300 kJ/week expended on recreational activities and stair climbing were 1.00 (referent), 1.04 (95% confidence interval, 0.77-1.40), 0.86 (0.64-1.17), and 0.80 (0.58-1.12), respectively; p-trend = 0.11. However, among postmenopausal women there was a significant inverse trend for all breast cancer; the corresponding relative risks were 1.0 (referent), 0.97 (0.68-1.4), 0.78 (0.54-1.1), and 0.67 (0.44-1.0), respectively; p-trend = 0.03. Physical activity was unrelated to breast cancers positive for both estrogen and progesterone receptors either among all or postmenopausal women (p-trend = 0.50 and 0.26, respectively). When we assessed only vigorous recreational activity, requiring > or = 6 METs or multiples of resting metabolic rate, we observed no significant associations with all or steroid hormone receptor positive breast cancer, either among all or postmenospausal women. CONCLUSIONS: These data suggest that physical activity during middle age and older is not uniformly associated with decreased breast cancer risk. Among postmenopausal women only, higher levels of physical activity may decrease the risk of breast cancer. This study, however, had limited statistical power to detect small effects.

Age Distribution↗
PubMed2001

A prospective cohort study of physical activity and body size in relation to prostate cancer risk (United States).

OBJECTIVES: To examine the associations of physical activity and body size with risk of prostate cancer. METHODS: At baseline in 1988, 8922 men (mean age 67 years) completed a health questionnaire which included information on physical activity, body weight, and waist girth. In a subgroup (74% of men), physical activity data also had been provided in 1962 or 1966 and again in 1977. Additionally, body weight measured at age 18 was available for 92% of men. During follow-up from 1988 through 1993, 439 men developed prostate cancer. RESULTS: In multivariate analyses that accounted for potential confounders, the RRs (95% CI) for < 4200, 4200-8399, 8400-12,599, and > or = 12,600 kJ/week of physical activity at baseline were 1.00 (referent), 1.13 (0.84-1.52), 0.96 (0.68-1.35), and 1.04 (0.79-1.38), respectively. For body mass indexes (BMI) of < 22.5, 22.5-24.9, 25.0-27.4, and > or = 27.5 kg/m2 at baseline, corresponding results were 1.00 (referent), 1.27 (0.94-1.71), 1.26 (0.92-1.72), and 1.02 (0.68-1.53), respectively. For waist girths of < or = 86.4, 86.5-91.4, 91.5-96.5, and > 96.5 cm, they were 1.00 (referent), 1.30 (0.96-1.76), 1.31 (0.96-1.80), and 1.19 (0.85-1.65), respectively. Combining physical activity measures from the past, or examining vigorous activities only, did not yield any significant associations. BMI at age 18 also was not related to risk. CONCLUSION: These findings do not support a role of physical activity or body weight in prostate cancer etiology.

Age Distribution↗
PubMed2001

Low-dose aspirin for migraine prophylaxis in women.

Although migraine is more common among women than men, the only two large, randomized trials of low-dose aspirin for migraine prophylaxis have been conducted in men. As part of the Women's Health Study, an ongoing randomized trial of low-dose aspirin and vitamin E among 39 876 female health professionals aged 45 and older, 1001 women with frequent migraine attacks were assigned to 100 mg of aspirin every other day (n = 525) or aspirin placebo (n = 476). Migraine frequency, as well as severity, duration, and degree of incapacitation, were assessed by self-report on questionnaires 12 months and 36 months after randomization, and also by monthly diaries kept before and after randomization. Women assigned to aspirin reported small and consistent decreases in migraine frequency (59.6% vs. 56.4% assigned to placebo reporting improvement at 36 months; odds ratio 1.13, 95% confidence interval, 0.86--1.48), as well as decreases in severity, duration, and migraine-related incapacitation. These reductions were not, however, statistically significant. These data are compatible with a small treatment effect of low-dose aspirin in the prophylaxis of migraine among middle-aged women.

Adult↗
PubMed2001

Toxicity and biodegradation of products from polyester hydrolysis.

Toxicity of products from polyester hydrolysis such as succinic acid (SA), adipic acid (AA), mandelic acid (MA), terephthalic acid (TA), 1,4-butanediol (1,4-B), ethylene glycol (EG), styrene glycol (SG) and 1,4-cyclohexane dimethanol (1,4-C) was evaluated by phytotoxicity test on germination of young radish seeds and by cytotoxicity test on HeLa cells. The phytotoxicity test revealed SG > MA > 1,4-C > AA approximately SA > TA approximately EG > 1,4-B in order of decreasing toxicity taking into consideration the growth behavior after germination as well as the percentage of germination. Toxicity on HeLa cells decreased in slightly different order compared to that on young radish seeds, i.e. SG > 1,4-C > MA > TA > SA > AA > EG > 1,4-B. Tests for the phytotoxicity and for cytotoxicity indicated that the aromatic compounds were more harmful than the aliphatic ones. Each group of 4 strains which grew most rapidly on each agar plate containing SA, AA, MA, TA, 1,4-B, EG, SG and 1,4-C respectively as a sole carbon source was identified by the fatty acid methyl esters analysis. The modified Sturm test was carried out using the single isolated strain, an activated sludge or a mixed soil to measure the rate of mineralization of the compounds into carbon dioxide. The aliphatic compounds were mineralized more easily than the aromatic compounds. 1,4-C showed the most exceptionally slow degradation. A scrutiny of residual 1,4-C after degradation is required before polyesters containing 1,4-C could be classified into compostable because 1,4-C has detrimental effects on young radish seeds and HeLa cells and has a tendency to accumulate in the environment due to its slow degradability.

Animals↗
PubMed2001

Epidemiologic data on the relationships of caloric intake, energy balance, and weight gain over the life span with longevity and morbidity.

Animal experiments have shown that calorically restricted (CR) animals weigh less and live longer than their ad libitum-fed peers. Are these observations applicable to human beings? This is an important question because the prevalence of obesity in America has increased markedly over recent years. We examine whether there are physiologic effects that occur with CR in humans that could plausibly explain the observed longevity of laboratory animals associated with CR. We also review epidemiologic data from observational and interventional studies on the relationships of caloric intake, energy balance, and weight gain with age-related diseases and longevity. Additionally, data on whether long-term, sustained maintenance of weight loss is feasible, as well as the degree of CR achieved in clinical trials, are summarized. Finally, we provide recommendations regarding further epidemiologic research that will help clarify unanswered questions in these areas.

Energy Intake↗
PubMed2001

Intake of vegetables rich in carotenoids and risk of coronary heart disease in men: The Physicians' Health Study.

BACKGROUND: Previous studies of diet and coronary heart disease (CHD) have focused on intake of nutrients rather than whole foods. Because of the findings that dietary fibre, folate and antioxidants may be protective for CHD, increased intake of vegetables has been recommended. However, due to the chemical and physical complexity of vegetables, the effects of individual nutrients may differ if eaten as whole foods. Moreover, little is known about the direct association between vegetable intake and risk of CHD. METHODS: We prospectively evaluated the relation between vegetable intake and CHD risk in the Physicians' Health Study, a randomized trial of aspirin and beta-carotene among 22 071 US male physicians aged 40-84 years in 1982. In this analysis, we included 15 220 men without heart disease, stroke or cancer at baseline who provided information on their vegetable intake at baseline, and in the 2nd, 4th and 6th years of follow-up using a simple semiquantitative food frequency questionnaire including eight vegetables. We confirmed 1148 incident cases of CHD (387 incident cases of myocardial infarction and 761 incident cases of coronary artery bypass grafting or percutaneous transluminal coronary angioplasty) during 12 years of follow-up. RESULTS: After adjusting for age, randomized treatment, body mass index (BMI), smoking, alcohol intake, physical activity, history of diabetes, history of hypertension, history of high cholesterol, and use of multivitamins, men who consumed at least 2.5 servings/day of vegetables had a relative risk (RR) of 0.77 (95% CI : 0.60-0.98) for CHD, compared with men in the lowest category (<1 serving/day). Adjusting for the same covariates in an analysis of the overall trend that considered intake of vegetables as a continuous variable, we found a RR of 0.83 (95% CI : 0.71-0.98) for risk of CHD for each additional serving/day of vegetables. The inverse relation between vegetable intake and CHD risk was more evident among men with a BMI > or =25 (RR = 0.71, 95% CI : 0.51-0.99) or current smokers (RR = 0.40, 95% CI : 0.18-0.86) comparing highest to the lowest categories of intake. CONCLUSIONS: Our results suggest an inverse association between vegetable intake and risk of CHD. These prospective data support current dietary guidelines to increase vegetable intake for the prevention of CHD.

Adult↗
PubMed2001

Alcohol consumption and risk of prostate cancer: The Harvard Alumni Health Study.

BACKGROUND: Although many studies suggest that consumption of alcohol increases the risk of several site-specific cancers, the evidence remains unclear for prostate cancer. Few data exist on beverage-specific associations as well as lifetime patterns of alcohol consumption and prostate cancer risk. METHODS: We prospectively followed 7612 Harvard alumni (mean age 66.6 years) from 1988 through 1993, during which 366 cases of incident prostate cancer occurred. Self-reported alcohol consumption was assessed at baseline from wine, beer, and liquor intake. Previous assessments during college and in 1977 were also available. RESULTS: Overall, the mean total alcohol consumption in 1988 was 123.1 g/week, of which 28.6% was from wine, 15.8% from beer, and 55.6% from liquor. Compared to men reporting almost never drinking alcohol in 1988, the multivariate relative risks (95% CI) for 1 drink/month to < 3 drinks/week, 3 drinks/week to < 1 drink/ day, 1 to < 3 drinks/day, and > or = 3 drinks/day were 1.33 (0.88-2.01), 1.65 (1.12-2.44), 1.85 (1.29-2.64), and 1.33 (0.86-2.05), respectively. Wine or beer consumption was unassociated with prostate cancer; however, moderate liquor consumption was associated with a significant 61-67% increased risk of prostate cancer (P, non-linear trend < 0.001). Men initiating alcohol consumption between 1977 and 1988 had a twofold increased risk of prostate cancer compared to men with almost no alcohol consumption at both times. CONCLUSIONS: In contrast to the majority of previous studies, we found a positive association between moderate alcohol consumption and the risk of prostate cancer. Liquor, but not wine or beer, consumption was positively associated with prostate cancer.

Aged↗
PubMed2001

A history of physical activity, cardiovascular health and longevity: the scientific contributions of Jeremy N Morris, DSc, DPH, FRCP.

Since Hippocrates first advised us more than 2000 years ago that exercise-though not too much of it--was good for health, the epidemiology of physical activity has developed apace with the epidemiological method itself. It was only in the mid-20th century that Professor Jeremy N Morris and his associates used quantitative analyses, which dealt with possible selection and confounding biases, to show that vigorous exercise protects against coronary heart disease (CHD). They began by demonstrating an apparent protection against CHD enjoyed by active conductors compared with sedentary drivers of London double-decker buses. In addition, postmen seemed to be protected against CHD like conductors, as opposed to less active government workers. The Morris group pursued the matter further, adapting classical infectious disease epidemiology to the new problems of chronic, non-communicable diseases. Realizing that if physical exercise were to be shown to contribute to the prevention of CHD, it would have to be accomplished through study of leisure-time activities, presumably because of a lack of variability in intensities of physical work. Accordingly, they chose typical sedentary middle-management grade men for study, obtained 5-minute logs of their activities over a 2-day period, and followed them for non-fatal and fatal diseases. In a subsequent study, Morris et al. queried such executive-grade civil servants by detailed mail-back questionnaires on their health habits and health status. They then followed these men for chronic disease occurrence, as in the earlier survey. By 1973 they had distinguished between 'moderately vigorous' and 'vigorous' exercise. In both of these civil service surveys, they demonstrated strong associations between moderately vigorous or vigorous exercise and CHD occurrence, independent of other associations, in age classes 35-64 years. In the last 30 years, with modern-day computers, a large number of epidemiological studies have been conducted in both sexes, in different ethnic groups, in broad age classes, in a variety of social groups, and on most continents of the world. These studies have extended and amplified those of the Morris group, thereby helping to solidify the cause-and-effect evidence that exercise protects against heart disease and averts premature mortality.

Cardiovascular Diseases↗
PubMed2001

Physical activity and all-cause mortality: what is the dose-response relation?

PURPOSE: The purpose of this review is to assess the dose-response relation between physical activity and all-cause mortality. We examined these parameters of physical activity dose: volume, intensity, duration, and frequency. METHODS: We used a computer-assisted literature search to identify papers on this topic. After excluding papers examining only two levels of physical activity or fitness, papers investigating specific causes of mortality, reviews, and those not written in English, 44 papers satisfying all criteria were included in this review. RESULTS: There is clear evidence of an inverse linear dose-response relation between volume of physical activity and all-cause mortality rates in men and women, and in younger and older (> or = 60 yr) persons. Minimal adherence to current physical activity guidelines, which yield an energy expenditure of about 1000 kcal x wk(-1) (4200 kJ x wk(-1)), is associated with a significant 20--30% reduction in risk of all-cause mortality. Further reductions in risk are observed at higher volumes of energy expenditure. It is unclear whether a volume of <1000 kcal x wk(-1) also may be associated with lower risk; there are some data supporting this. Due to limited data, it is also unclear whether vigorous-intensity activity confers additional benefit beyond its contribution to volume of physical activity when compared with moderate-intensity activity. No data are available on duration and frequency of physical activity in relation to all-cause mortality rates after controlling for volume of physical activity. CONCLUSIONS: All studies in this review are observational studies, so conclusions are based on Evidence Category C. There is an inverse linear dose-response relation between volume of physical activity and all-cause mortality. Further research is needed to clarify the contributions of its components--intensity, duration, and frequency--to decreased all-cause mortality rates.

Adult↗
PubMed2001

Serologic evaluations of women exposed to breast implants.

OBJECTIVE: There continues to be uncertainty whether women with silicone breast implants experience activation of their immune system and show increased prevalence of serologic markers of connective tissue diseases. We conducted laboratory tests in a large number of women with and without breast implants, and in diabetic patients with presumed silicone exposure via insulin syringes. METHODS: Subjects were chosen from women enrolled in the run-in phase of the Women's Health Study (WHS, a randomized trial testing aspirin and vitamin E in preventing cardiovascular disease and cancer), and included 298 women without breast implants, 298 women with breast implants, and 52 diabetic patients diagnosed before age 30. Comparison groups were matched on age, race, date of blood provided to the WHS, and randomization status. We compared the proportion with abnormal results in 16 serologic tests among the 3 groups of women, stratifying by the matching factors. We also tested for monoclonal immunoglobulins by electrophoresis. RESULTS: For 14 of the 16 serologic tests, the proportions with abnormal results among the 3 groups of women were not significantly different. Of the remaining tests, C3 levels were decreased in 8 (2.7%) women without breast implants and 22 (7.4%) women with breast implants (p = 0.003). C4 levels were decreased in 31 (10.4%) women without breast implants and 48 (16.1%) women with breast implants (p = 0.03). Women without breast implants and diabetic patients did not differ significantly in the proportions having decreased C3 and C4 levels. Women with breast implants did not have higher frequency of monoclonal immunoglobulins detected by electrophoresis. CONCLUSION: We found little evidence for activation of the immune system in women with breast implants. The clinical significance of isolated reductions in C3 and C4 levels, in the absence of other abnormalities such as elevated levels of antinuclear antibody, is unknown.

Antibodies, Antinuclear↗