Search PubMed⌕ Search

Biomedical subjects

I M Lee

Publications and source records attributed to I M Lee.

At least 91 records · Page 5Linked to original sources
PubMed1994

Birth weight and handedness in boys and girls.

The association between selected demographic variables and birth weight on the one hand and a composite hand preference score based on seven hand tasks (each performed twice) on the other was investigated in a sample of 1387 male and female schoolchildren aged 5 to 10 years old. In multiple regression models left-handedness was significantly more common among boys and among children of better educated mothers and tended to decrease with age. No association was found with respect to urban or rural residence or birth order. Increased birth weight was associated with right-handedness in boys but with left-handedness in girls, and the birth weight by sex interaction term was statistically significant (p = 0.037). The demographic associations in the present study are compatible with those reported previously. The different associations of birth weight with hand preference in boys and girls indicate that the prenatal hormonal factors that affect brain lateralization and handedness are qualitatively or quantitatively different in the two sexes and may be differentially associated with birth weight.

Age Factors↗
PubMed1994

Physical activity and its relation to cancer risk: a prospective study of college alumni.

Previous investigations regarding the influence of physical activity on cancer risk generally have utilized a single assessment of activity, thus failing to account for changes over time. Additionally, one assessment may be somewhat imprecise. We attempted to overcome these problems in a study of 17,607 men (aged 30-79 yr), followed from 1962 or 1966 (1962/1966) through 1988. We assessed physical activity (based on self-reported stair climbing, walking and participation in sports or recreational activities) twice: in 1962/1966 and again in 1977. A total of 280 colon, 53 rectal, 454 prostatic, 262 lung, and 88 pancreatic cancers developed during follow-up. Among alumni with Quetelet's index > or = 26 units, those highly active (energy expenditure > or = 2,500 kcal [> or = 10,460 kJ].wk-1) had 0.19 (95% confidence interval, 0.02-1.52) to 0.56 (0.29-1.09) times the colon cancer risk of those inactive (< 1,000 kcal [< 4,184 kJ].wk-1). Colon cancer risk was unrelated to level of activity among alumni with Quetelet's index < 26 units. Highly active alumni also had 0.39 (95% confidence interval, 0.18-0.85) to 0.62 (0.45-0.85) times the lung cancer risks of their inactive colleagues. Physical activity was not significantly associated with risks of rectal, prostatic, or pancreatic cancers. The biologic basis for a protective effect of increased activity on cancer risk appears plausible.

Adult↗
PubMed1994

Changes in physical activity and other lifeway patterns influencing longevity.

We studied the adoption or maintenance of physical activity and other optional lifeway patterns for their influence on mortality rates of Harvard College alumni. Men aged 45-84 in 1977, surveyed by questionnaire in 1962 or 1966 and again in 1977, were followed from 1977 through 1988 or to age 90. Of 14,786 alumni, 2,343 died in 165,402 man-years of follow-up. Relative risks of death, standardized for potential confounding influences, for men who between questionnaires increased their physical activity through walking, stair climbing, and sports or recreational activities to 1,500 kcal or more per wk were 0.72 (95% confidence interval 0.64-0.82), compared with 1.00 for men who remained less active. Corresponding relative risks for men who adopted moderately vigorous sports play (> or = 4.5 METs) were 0.73 (0.65-0.81) vs 1.00 for men not adopting such sports; and for cigarette smokers who quit, 0.74 (0.65-0.84) vs 1.00 for persistent smokers. Men with recently diagnosed hypertension had a lower death risk than long-term hypertensives (0.80; 0.70-0.92), as did men with consistent normotension (0.52; 0.47-0.58). Changes in body-mass index had little influence on mortality during follow-up. These findings fit the hypothesis that adopting a physically active lifeway, quitting cigarette smoking, and remaining normotensive independently delay all-cause mortality and extend longevity.

Adult↗
PubMed1993

Body weight and mortality. A 27-year follow-up of middle-aged men.

OBJECTIVE: To investigate the nature of the relation between body weight and all-cause mortality. DESIGN: Prospective cohort study, following up men from 1962 or 1966 (1962/1966) through 1988. SETTING/PARTICIPANTS: Harvard University alumni with a mean age of 46.6 years in 1962/1966 and without self-reported, physician-diagnosed coronary heart disease, stroke, or cancer, who completed questionnaires on weight, height, cigarette smoking habit, and physical activity (n = 19,297). We calculated body mass index (weight in kilograms divided by the square of height in meters) using self-reported measures. MAIN OUTCOME MEASURE: All-cause mortality (4370 deaths). RESULTS: In multivariate analysis adjusting for age, cigarette smoking habit, and physical activity, we found a J-shaped relation between body mass index and mortality. Relative risks of dying for men with a body mass index of less than 22.5, 22.5 to less than 23.5, 23.5 to less than 24.5, 24.5 to less than 26.0, and 26.0 or greater were 1.00 (referent), 0.99 (95% confidence interval, 0.89 to 1.20), 0.95 (0.87 to 1.05), 1.01 (0.91 to 1.10), and 1.18 (1.08 to 1.28), respectively (P for linear trend = .0008). Among current smokers, the relation between body mass index and mortality was U-shaped, with lowest risk of death at a body mass index of 23.5 to less than 24.5. During early follow-up (1962/1966 through 1974), we also observed a U-shaped curve, this time with lowest mortality risk at a body mass index of 24.5 to less than 26.0. To minimize confounding by cigarette smoking and bias from antecedent disease and early mortality, we conducted analysis only among never smokers and omitted the first 5 years of follow-up (510 deaths). The corresponding relative risks from this analysis, adjusted for age and physical activity, were 1.00, 1.23 (95% confidence interval, 0.90 to 1.67), 1.06 (0.80 to 1.42), 1.27 (0.96 to 1.68), and 1.67 (1.29 to 2.17), respectively (P for linear trend = .0001). CONCLUSIONS: In these prospective data, body weight and mortality were directly related. After accounting for confounding by cigarette smoking and bias resulting from illness-related weight loss or inappropriate control for the biologic effects of obesity, we found no evidence of excess mortality among lean men. Indeed, lowest mortality was observed among men weighing, on average, 20% below the US average for men of comparable age and height.

Body Mass Index↗
PubMed1993

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

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 = 0.015) than not taking up moderately vigorous sports. Quitting cigarette smoking was associated with a 41 percent lower risk (95 percent confidence interval, 20 to 57 percent; P = 0.001) than continuing smoking, but with a 23 percent higher risk than constant nonsmoking. Men with recently diagnosed hypertension had a lower risk of death than those with long-term hypertension (relative risk, 0.75; 95 percent confidence interval, 0.55 to 1.02; P = 0.057), as did men with consistently normal blood pressure (relative risk, 0.52; 95 percent confidence interval, 0.40 to 0.68; P < 0.001). Maintenance of lean body mass was associated with a lower mortality rate than long-term, recent, or previous obesity. The associations between changes in lifestyle and mortality were independent and were largely undiminished by age. Our findings on death from coronary heart disease mirrored those on death from all causes. CONCLUSIONS: Beginning moderately vigorous sports activity, quitting cigarette smoking, maintaining normal blood pressure, and avoiding obesity were separately associated with lower rates of death from all causes and from coronary heart disease among middle-aged and older men.

Aged↗
PubMed1993

Measurement of physical activity to assess health effects in free-living populations.

For physical activity surveys that would identify relations to chronic diseases, quality of life, and longevity, the method of choice remains the questionnaire, especially if it can be standardized and administered in uniform fashion to large populations. A sample questionnaire derived largely from epidemiological experience with the Harvard Alumni Health Study is presented that requests anthropometric estimates; physician-diagnosed diseases by year of onset; contemporary physical activities including walking, stair-climbing, and recreational pursuits; food-frequency data that estimate nutrient values and caloric intakes; and social habits affecting health. The questionnaire presents opportunities for cross-sectional, retrospective, and prospective studies. Personal characteristics, physical activities, and other elements of lifestyle may be used as predictor or outcome variables in testing specific hypotheses. Representative surveys are described that have validated and used questionnaires of various complexities, some complemented by measures of physiological fitness. The epidemiological survey questionnaire, when properly designed and administered, can measure effectively energy intake, energy retention, energy expenditure, physiological fitness, quality of life, and health maintenance.

Exercise↗
PubMed1992

Change in body weight and longevity.

OBJECTIVE: To investigate the effect of body weight change on longevity. DESIGN: Cohort analytic study, following men from 1977 through 1988. SETTING: The study was conducted among Harvard University alumni with mean age of 58 years. PATIENTS: Alumni, free of cardiovascular disease and cancer, completed questionnaires on weight, height, cigarette habit, and physical activities in 1962 or 1966 and in 1977 (n = 11,703). We assessed weight change between questionnaires, based on self-reported weights. MAIN OUTCOME MEASURE: Mortality from all causes (n = 1441), coronary heart disease (n = 345), and cancer (n = 459), determined from death certificates. RESULTS: Lowest all-cause mortality was among alumni maintaining stable weight (+/- 1 kg). With this category as referent (relative risk = 1.00), relative risks of death associated with losing more than 5 kg, losing between 1 and 5 kg, (more than 1 kg and up to 5 kg) gaining between 1 and 5 kg (more than 1 kg and up to 5 kg), and gaining more than 5 kg were 1.57 (95% confidence interval, 1.34 to 1.84), 1.26 (1.10 to 1.46), 1.06 (0.90 to 1.24), and 1.36 (1.11 to 1.66), respectively. For coronary heart disease mortality, relative risks were 1.75 (1.26 to 2.43), 1.43 (1.05 to 1.93), 1.28 (0.91 to 1.80), and 2.01 (1.36 to 2.97), respectively. Weight change did not predict cancer mortality. Findings were not explained by cigarette habit, physical activity, or body mass index. We observed similar trends for follow-up between 1977 and 1982 and between 1983 and 1988. Those losing or gaining more weight also reported greater total lifetime weight loss, which may indicate weight cycling. CONCLUSIONS: Both body weight loss and weight gain are associated with significantly increased mortality from all causes and from coronary heart disease but not from cancer.

Analysis of Variance↗
PubMed1992

Quetelet's index and risk of colon cancer in college alumni.

BACKGROUND: While previous studies suggest that overweight, middle-aged men may face increased risk of colon cancer, it is unclear whether their weights as young adults influence this risk. It is also unknown whether their level of physical activity affects their risk of developing colon cancer. PURPOSE: To determine the relationship between being overweight in middle-age or young adulthood and colon cancer risk, we prospectively studied alumni of Harvard University. We also investigated whether being overweight influences risk differently for men with different levels of physical activity. METHODS: In 1962 or 1966 (1962/1966), alumni completed questionnaires on weight, height, other sociodemographic characteristics, and medical history. We obtained information on weight and height at college entry from university archives. Alumni (n = 17,595) were followed from 1962/1966 to 1988 for colon cancer occurrence, ascertained from follow-up questionnaires in 1977 and 1988 and death certificates. RESULTS: Between 1962/1966 and 1988, 302 cases of colon cancer were diagnosed. Colon cancer risk increased with higher levels of Quetelet's index (weight [kg]/height [m]2) in 1962/1966. Relative risk per unit increase, adjusted for age, physical activity, and parental history of cancer, was 1.08 (95% confidence interval [CI], 1.04-1.13). Quetelet's index at college entry did not predict risk as well (adjusted relative risk per unit increase, 1.05; 95% CI, 1.00-1.10). The heaviest fifth of alumni during both college time and in 1962/1966 had almost two and one-half times the risk of the lightest fifth of alumni (adjusted relative risk, 2.40; 95% CI, 1.40-4.13). When alumni were classified according to activity level in 1962/1966, higher levels of Quetelet's index were significantly associated with colon cancer risk only among those who were less active. CONCLUSIONS: Overweight during middle-age or young adulthood is associated with higher colon cancer risk; in overweight, physically active men, however, the risk of colon cancer may not be increased.

Adult↗
PubMed1992

Sensitive detection and identification of mycoplasma-like organisms in plants by polymerase chain reactions.

DNA amplification by polymerase chain reactions (PCR) was employed to detect host plant infection by several mycoplasmalike organisms (MLOs), including the aster yellows (AY), dwarf aster yellows (DAY), and periwinkle little leaf (0-1) MLOs. For PCR, two pairs of oligonucleotide primers, designated AY18pm and AY19pm, respectively, were synthesized on the basis of partial sequences of cloned AY MLO DNA fragments AY18 and AY19. Reaction mixtures containing primer pair AY18pm yielded a DNA product of 1.6Kbp, when template consisted of DNA extracted from AY MLO- or DAY MLO-infected Catharanthus roseus (periwinkle). A DNA product of 1.0Kbp was obtained with primer pair AY19pm, when template consisted of DNA extracted from C. roseus infected by AY MLO, DAY MLO, or periwinkle little leaf (strain O-1) MLO. MLO-specific bands were observed when reaction mixtures contained as little as 5 pg total nucleic acid from infected plants. No PCR product was observed when reaction mixtures contained only DNA from healthy plants or DNA from plants infected by western X MLO or by tomato big bud MLO. The findings indicated that the PCR system is useful for sensitive detection and differentiation of MLOs in infected hosts.

Base Sequence↗
PubMed1992

Time trends in physical activity among college alumni, 1962-1988.

Little direct evidence exists in the epidemiologic literature to support the widely held belief that an individual's physical activity behavior varies over the years. To provide data, the authors prospectively studied patterns of physical activity among 6,092 Harvard College alumni (average age at the start of follow-up, 43 years) who responded to questionnaires in 1962 or 1966, 1977, and 1988, and who declared themselves free of cardiovascular disease and cancer throughout that period. The median energy expenditure increased between 1962 or 1966 and 1977, but stabilized between 1977 and 1988. However, rank correlation coefficients between estimates of energy expenditure in 1977 and 1988 ranged from 0.36 to 0.41 for the various age groups (compared with 0.81-0.84 for the Quetelet index, and 0.60-0.65 for the current number of cigarettes smoked per day), implying that physical activity at the individual level was not constant. For 4,238 alumni for whom data on collegiate sports participation were available, the rank correlation coefficients between collegiate activity and alumni activity 1-7 decades later were even lower, ranging from 0.05 to 0.17 (compared with 0.31-0.58 for the Quetelet index). Thus, physical activity assessed over a short time period in an individual may not be a valid proxy for activity over the long term. The characteristics that distinguished alumni who consistently expended less than 1,000 kcal/week (in climbing stairs, walking, and playing sports) in 1962 or 1966, 1977, and 1988 from those who consistently expended greater than 2,500 kcal/week were as follows: at baseline, older age, overweight, and cigarette smoking; and during college, not having been a varsity athlete and fewer hours playing sports.

Adult↗
PubMed1992

Physical activity and risk of prostatic cancer among college alumni.

Clinical observations and laboratory experiments have suggested a role for testosterone in the development of prostatic cancer. Since physical training may act to lower testosterone levels, men who are very active may have a reduced risk of this cancer. To test this hypothesis, the authors prospectively followed 17,719 Harvard alumni (aged 30-79 years) from 1965 or 1969 to 1977, and 1980 to 1988 for the occurrence of prostatic cancer (n = 419). Physical activity was assessed in either 1962 or 1966, and again in 1977, based on self-reported stair climbing, walking, and sports played. Alumni who expended greater than 4,000 kcal/week at both assessments were at reduced risk of developing prostatic cancer (age-adjusted rate ratio, 0.12; 95% confidence interval 0.02-0.89) compared with their inactive counterparts who expended less than 1,000 kcal/week at both assessments. These results should be interpreted cautiously, since only one case of prostatic cancer was identified among alumni highly active at both assessments, who contributed 4% of total person-years to the analysis. Among alumni aged 70 years and older, those who extended greater than 4,000 kcal/week at either assessment had about half the risk of those who expended less than 1,000 kcal/week at either assessment (age-adjusted rate ratio, 0.53; 95% confidence interval 0.29-0.95). The authors attribute these findings to the increased precision with which physical activity could be measured when combining two activity assessments. Alternatively, long-term maintenance of a high level of physical activity may be necessary for further reduction of risk. There was no evidence of a dose-response relation.

Adult↗
PubMed1992

Identification and analysis of a genomic strain cluster of mycoplasmalike organisms associated with Canadian peach (eastern) X disease, western X disease, and clover yellow edge.

Genetic interrelatedness among 13 strains of mycoplasmalike organisms (MLOs) from various sources was evaluated by dot hybridization and restriction fragment length polymorphism analyses using cloned DNA probes derived from Canadian peach X (CX) and western X (WX) MLOs. Dot hybridization analysis indicated that CX, WX, and clover yellow edge MLOs are closely related and form a distinct strain cluster that is only distantly related to the 10 other MLOs. Similarity coefficients derived from restriction fragment length polymorphism analysis revealed that CX, WX, and clover yellow edge MLOs represent three distinct genomic types.

Blotting, Southern↗
PubMed1991

Physical activity and risk of developing colorectal cancer among college alumni.

The assessment of physical activity at a single time to evaluate its association with cancer may be limited, since such a measure may not adequately reflect activity over the long term. To overcome this limitation, we studied 17,148 Harvard alumni aged 30-79 years who were followed prospectively for the occurrence of colon cancer (n = 225) and rectal cancer (n = 44) from 1965 through 1988. Physical activity, based on self-reported stair climbing, walking, and sports play, was assessed in either 1962 or 1966 (1962/1966) and again in 1977. The increased activity evaluated using either assessment (1962/1966 or 1977) taken alone was not associated with risk of colon cancer. However, alumni who were highly active (energy expenditure of greater than 2500 kilocalories/wk) at both assessments had half the risk of developing colon cancer relative to those who were inactive (less than 1000 kilocalories/wk) at both assessments (age-adjusted rate ratio = 0.50; 90% confidence interval = 0.27-0.93), whereas those who were moderately active (1000-2500 kilocalories/wk) at both assessments had an age-adjusted rate ratio of 0.52 (90% confidence interval = 0.28-0.94). We conclude that either consistently higher levels of activity are necessary to protect against colon cancer or combining two assessments increased the precision of physical activity measurement. We found no evidence that increased physical activity protected against rectal cancer.

Adult↗
PubMed1991

Genetic Interrelatedness among Clover Proliferation Mycoplasmalike Organisms (MLOs) and Other MLOs Investigated by Nucleic Acid Hybridization and Restriction Fragment Length Polymorphism Analyses.

DNA was isolated from clover proliferation (CP) mycoplasmalike organism (MLO)-diseased periwinkle plants (Catharanthus roseus (L.) G. Don.) and cloned into pSP6 plasmid vectors. CP MLO-specific recombinant DNA clones were biotin labeled and used as probes in dot hybridization and restriction fragment length polymorphism analyses to study the genetic interrelatedness among CP MLO and other MLOs, including potato witches'-broom (PWB) MLO. Results from dot hybridization analyses indicated that both a Maryland strain of aster yellows and a California strain of aster yellows are distantly related to CP MLO. Elm yellows, paulownia witches'-broom, peanut witches'-broom, loofah witches'-broom, and sweet potato witches'-broom may be very distantly related, if at all, to CP MLO. A new Jersey strain of aster yellows MLO, tomato big bud MLO, clover phyllody MLO, beet leafhopper-transmitted virescence MLO, and ash yellows MLO are related to CP MLO, but PWB MLO is the most closely related. Similarity coefficients derived from restriction fragment length polymorphism analyses revealed that PWB and CP MLOs are closely related strains and thus provided direct evidence of their relatedness in contrast to reliance solely on biological characterization.

Journal Article↗
PubMed1990

Nonradioactive screening method for isolation of disease-specific probes to diagnose plant diseases caused by mycoplasmalike organisms.

DNA fragments of tomato big bud (BB) mycoplasmalike organism (MLO) in diseased periwinkle plants (Catharanthus roseus L.) were cloned to pSP6 plasmid vectors and amplified in Escherichia coli JM83. A nonradioactive method was developed and used to screen for MLO-specific recombinants. Cloned DNA probes were prepared by nick translation of the MLO recombinant plasmids by using biotinylated nucleotides. The probes all hybridized with nucleic acid from BB MLO-infected, but not healthy, plants. Results from dot hybridization analyses indicated that several MLOs, e.g., those of Italian tomato big bud, periwinkle little leaf, and clover phyllody, are closely related to BB MLO. The Maryland strain of aster yellows and maize bushy stunt MLOs are also related to BB MLO. Among the remaining MLOs used in this study, Vinca virescence and elm yellows MLOs may be very distantly related, if at all, to BB MLO. Potato witches' broom, clover proliferation, ash yellows, western X, and Canada X MLOs are distantly related to BB MLO. Southern hybridization analyses revealed that BB MLO contains extrachromosomal DNA that shares sequence homologies with extrachromosomal DNAs from aster yellows and periwinkle little leaf MLOs.

Journal Article↗