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Biomedical subjects

M L Stefanick

Publications and source records attributed to M L Stefanick.

At least 19 recordsLinked to original sources
PubMed2000

Correlates of high HDL cholesterol among women with coronary heart disease.

BACKGROUND: The National Cholesterol Education Program (NCEP) has designated high-density lipoprotein cholesterol (HDL-C) > or =60 mg/dL a "negative" coronary heart disease (CHD) risk factor, but a substantial proportion of coronary events occur among women despite high HDL-C levels. METHODS AND RESULTS: The objective of this study was to characterize postmenopausal women with prevalent CHD despite HDL-C > or =60 mg/dL and to identify factors that may attenuate the protective effect of high HDL-C. We analyzed baseline data from a randomized, double-blind study of estrogen/progestin replacement therapy in 2763 postmenopausal women <80 years old with CHD. Demographics, CHD risk factors, medications, anthropometrics, and lipid levels were compared among women with low, normal, and high HDL-C by NCEP criteria with and without stratification by use of lipid-lowering medications. Independent correlates of high HDL-C were determined by logistic regression analysis. HDL-C > or =60 mg/dL was present in 20% of participants. Women with high HDL-C were older, better educated, had fewer CHD risk factors, lower triglyceride levels and total cholesterol/HDL-C ratio, and were more likely to report past estrogen and current calcium antagonist, niacin, and statin use. beta-Blocker, diuretic, and fibrate use was less common. Older age, alcohol consumption, niacin, and calcium antagonist use and prior estrogen use were independently associated with high HDL-C, whereas waist-to-hip ratio, smoking, triglyceride level, and beta-blocker and fibrate use were inversely associated (all P <.05). CONCLUSIONS: High HDL-C, as defined by the NCEP, occurred in 20% of women with CHD in this cohort without a concomitantly higher prevalence of other CHD risk factors. Redefinition of "high" HDL-C levels for women may be warranted.

Adult↗
PubMed1999

Effect of postmenopausal hormones on inflammation-sensitive proteins: the Postmenopausal Estrogen/Progestin Interventions (PEPI) Study.

BACKGROUND: Observational studies in healthy women suggest postmenopausal hormone therapy reduces risk of coronary events. In contrast, in a recent clinical trial of women with coronary disease, a subgroup analysis demonstrated increased risk during the early months of therapy. Because higher levels of inflammation factors predict vascular disease outcomes, the effect of hormones on these factors is of interest. METHODS AND RESULTS: Four inflammation-sensitive factors, C-reactive protein, soluble E-selectin, von Willebrand factor antigen, and coagulation factor VIIIc were measured at baseline, 12, and 36 months in 365 participants of the Postmenopausal Estrogen/Progestin Interventions (PEPI) Trial, a randomized, placebo-controlled trial of the effects of 4 hormone preparations on cardiovascular disease risk factors. Compared with placebo, all 4 active preparations resulted in a large sustained increase in the concentration of C-reactive protein and a decrease in soluble E-selectin (P=0.0001). There were no effects of treatment on concentrations of von Willebrand factor or factor VIIIc. There were no differences in effects among treatment arms. Relative to placebo, when combining active treatment arms, final concentrations of C-reactive protein were 85% higher whereas E-selectin was 18% lower compared with baseline. CONCLUSIONS: Postmenopausal hormones rapidly increased the concentration of the inflammation factor C-reactive protein. Such an effect may be related to adverse early effects of estrogen therapy. In contrast, hormones reduced the concentration of soluble E-selectin, and this might be considered an anti-inflammatory effect. Because PEPI was not designed to assess clinical endpoints, studies of the impact of hormone-mediated changes in inflammation on risk of subsequent coronary events are needed.

Antigens↗
PubMed1999

Factors associated with weight gain in women after diagnosis of breast cancer. Women's Healthy Eating and Living Study Group.

OBJECTIVE: To identify the factors associated with weight gain after diagnosis of breast cancer in a heterogeneous population of women. DESIGN: Descriptive cross-sectional study. SUBJECTS: 1,116 patients who had been diagnosed with stage I, stage II, or stage IIIA primary, operable breast cancer within the previous 4 years. Patients were recruited during enrollment into a diet intervention trial to reduce risk for breast cancer recurrence. Analysis Demographic data, weight history, and physical activity information obtained by questionnaire and medical information obtained by chart review; dietary assessment based on four 24-hour dietary recalls collected by telephone. Associations between weight change after the diagnosis of breast cancer and prediction variables were examined using univariate and multiple linear regression analyses. RESULTS: Overall, 60% of the subjects reported weight gain, 26% reported weight loss, and 14% reported no change in weight after the diagnosis of breast cancer. The overall mean weight change was a gain of 2.7 kg (6 lb). Factors positively and independently associated with weight gain were time since diagnosis of breast cancer, adjuvant chemotherapy, African-American ethnicity, current energy intake, and postmenopausal status at time of study entry. Factors inversely and independently associated with weight gain were prediagnosis body mass index, age at diagnosis, education level, and exercise index score. APPLICATIONS: Higher energy intake and lower level of physical activity are independently associated with increased risk for weight gain after the diagnosis of breast cancer. Strategies to modify these behaviors are likely to influence the long-term pattern of weight change.

Adult↗
PubMed1999

Effect of hormone replacement therapy on the validity of the Friedewald equation in postmenopausal women: the postmenopausal estrogen/progestins interventions (PEPI) trial.

The Friedewald equation is often used to estimate low-density lipoprotein cholesterol (LDL-C). Hormone therapy is known to raise triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) and alter lipid contents of lipoproteins. We compared Friedewald estimated LDL-C to measured LDL-C in PEPI participants on placebo or four different hormone treatment groups. At baseline, the 0.2 coefficient for triglyceride (TG) was accurate for all five treatment groups. Among women who took >80% of their pills and whose TG was <4.5 mmol/l (400 mg/dl), LDL-C was underestimated for 69-82% of the participants in the active treatment groups, compared to 50% in the placebo group. After 3 years of therapy, the TG coefficient that offered a better fit of the Friedewald equation in the active treatment groups was 0.39 for the equation in mmol/l (0.17 for the equation in mg/dl). Using this coefficient is clearly warranted for greater accuracy in research studies.

Algorithms↗
PubMed1999

Knowledge and perceived risk of major diseases in middle-aged and older women.

Women's (N = 200; 41-95 years) knowledge of mortality risks and their perceived general risk, personal risk, control, and preventability of coronary heart disease (CHD) and breast, colon, and lung cancer were examined. Middle-aged (MA) women were more accurate in their mortality knowledge for MA men than for MA women and were more accurate for MA than for older (OA) men and women. OA women, in contrast, were least accurate in their mortality knowledge for OA women compared with all other target groups; only 34% knew that CHD is the leading cause of death in OA women. Participants also overestimated a woman's risk of death from breast cancer and underestimated the risk from lung and colon cancer. Ratings of perceived risk, control, and preventability varied as a function of disease. OA women in particular appear to lack knowledge regarding women's risk of major diseases. Results have implications for women's health behaviors and medical decisions.

Adult↗
PubMed1999

Physical activity for preventing and treating obesity-related dyslipoproteinemias.

PURPOSE: The clinical trial data were reviewed on effects of physical activity on obesity-related dyslipoproteinemias (specifically low HDL-cholesterol (HDL-C), elevated triglycerides (TG), and high total and LDL-cholesterol (TC and LDL-C)) in adult men and women. METHODS: Effort was made to identify all randomized clinical trials (RCT), with exercise intervention programs of at least 4 months' duration, which had lipoprotein outcomes. Those that had both an exercise only intervention and control groups or both a diet plus exercise and identical diet only intervention groups were reviewed. Tables were developed of baseline characteristics and weight and lipoprotein changes for aerobic exercise trials by body mass index: 1) < 25.0 kg x m(-2), 2) 25.0-29.9 kg x m(2), and 3) > or = 30.0 kg x m(-2)and for studies involving resistance exercise or increased energy expenditure from daily activities versus structured exercise programs. RESULTS: Very few RCT were found that specifically addressed the role of physical activity in preventing or treating obesity-related adverse lipoprotein levels. There was essentially no evidence found in lean or overweight men or women to support a specific role for exercise in improving undesirable lipoprotein levels; however, trial data strongly suggest that the addition of exercise to a hypocaloric, reduced-fat diet improves HDL-C and TG in men and women with generally desirable initial levels and reduces LDL-C in men and women with initially elevated LDL-C levels. The evidence is also reasonably strong that weight loss, including that achieved solely by exercise, improves HDL-C and TG in obese men, without reducing LDL-C, whereas it remains weak for women. There are also virtually no trial data to support a role for resistance exercise or an increase in daily living activities for improving obesity-related lipoproteins. CONCLUSIONS: Current evidence from RCT is too limited to determine whether physical activity can raise low HDL-C or lower high TG or LDL-C levels in overweight and obese individuals.

Adult↗
PubMed1998

Effects of diet and exercise in men and postmenopausal women with low levels of HDL cholesterol and high levels of LDL cholesterol.

BACKGROUND: Guidelines established by the National Cholesterol Education Program (NCEP) promote exercise and weight loss for the treatment of abnormal lipoprotein levels. Little is known, however, about the effects of exercise or the NCEP diet, which is moderately low in fat and cholesterol, in persons with lipoprotein levels that place them at high risk for coronary heart disease. METHODS: We studied plasma lipoprotein levels in 180 postmenopausal women, 45 through 64 years of age, and 197 men, 30 through 64 years of age, who had low high-density lipoprotein (HDL) cholesterol levels (< or =59 mg per deciliter in women and < or =44 mg per deciliter in men) and moderately elevated levels of low-density lipoprotein (LDL) cholesterol (>125 mg per deciliter but <210 mg per deciliter in women and >125 mg per deciliter but <190 mg per deciliter in men). The subjects were randomly assigned to aerobic exercise, the NCEP Step 2 diet, or diet plus exercise, or to a control group, which received no intervention. RESULTS: Dietary intake of fat and cholesterol decreased during the one-year study (P<0.001), as did body weight, in women and men in either the diet group or the diet-plus-exercise group, as compared with the controls (P<0.001) and the exercise group (P<0.05), in which dietary intake and body weight were unchanged. Changes in HDL cholesterol and triglyceride levels and the ratio of total to HDL cholesterol did not differ significantly among the treatment groups, for subjects of either sex. The serum level of LDL cholesterol was significantly reduced among women (a decrease of 14.5+/-22.2 mg per deciliter) and men (a decrease of 20.0+/-17.3 mg per deciliter) in the diet-plus-exercise group, as compared with the control group (women had a decrease of 2.5+/-16.6 mg per deciliter, P<0.05; men had a decrease of 4.6+/-21.1 mg per deciliter, P<0.001). The reduction in LDL cholesterol in men in the diet-plus-exercise group was also significant as compared with that among the men in the exercise group (3.6+/-18.8 mg per deciliter, P<0.001). In contrast, changes in LDL cholesterol levels were not significant among the women (a decrease of 7.3+/-18.9 mg per deciliter) or the men (10.8+/-18.8 mg per deciliter) in the diet group, as compared with the controls. CONCLUSIONS: The NCEP Step 2 diet failed to lower LDL cholesterol levels in men or women with high-risk lipoprotein levels who did not engage in aerobic exercise. This finding highlights the importance of physical activity in the treatment of elevated LDL cholesterol levels.

Adult↗
PubMed1998

Characteristics of successful and unsuccessful dieters: an application of signal detection methodology.

Signal detection methods were used to identify predictors of successful weight loss in 177 mildly to moderately overweight women and men assigned to one of two weight-loss programs. Predictors included initial demographic, physiological, behavioral, and psychosocial characteristics, and program type (e.g. diet-only and diet-plus-exercise). Successful weight loss was defined as a loss of at least two units of body mass index at one year. Four subgroups were identified. Participants in the diet-plus-exercise program who were initially more satisfied with their bodies and did not have a history of repeated weight loss were most likely to succeed (63% succeeded). In contrast, participants assigned to the diet-plus-exercise program who were either extremely dissatisfied with their bodies or who had a history of repeated weight loss were at similar risk for failure as participants in the diet-only program (only 26% to 35% succeeded). The results underscore the potential utility of exploring these subgroups further to inform the development of new treatment strategies to increase the likelihood of success.

Adult↗
PubMed1997

Effect of postmenopausal hormone therapy on body weight and waist and hip girths. Postmenopausal Estrogen-Progestin Interventions Study Investigators.

Reports from cross-sectional comparisons, nonrandomized prospective studies, and relatively small clinical trials indicate that postmenopausal hormone therapy may slightly decrease the amount of weight typically gained by women during the decade following menopause. Despite this, widespread belief remains that hormone therapy may cause weight gain. We use data from the Postmenopausal Estrogen/Progestin Interventions trial to characterize the impact of postmenopausal hormone therapy on weight and fat distribution and to examine the consistency of this impact among subgroups of women defined by lifestyle, clinical, and demographic factors. The Postmenopausal Estrogen/Progestin Interventions trial was a 3-yr, placebo-controlled, randomized clinical trial of 875 women assessing the effects on cardiovascular risk factors of four hormone regimens: oral conjugated equine estrogen (CEE) therapy (0.625 mg daily alone), CEE in combination with medroxyprogesterone acetate (2.5 mg daily), CEE in combination with medroxyprogesterone acetate (10 mg daily on days 1-12), and CEE in combination with micronized progesterone (200 mg daily on days 1-12). Women randomly assigned to CEE with or without a progestational agent averaged 1.0 kg less weight gain at the end of 3 yr (P = 0.006) than those assigned to placebo. Assignment to CEE was also associated with averages of 1.2 cm less increase in waist girth (P = 0.01) and 0.3 cm less increase in hip (P = 0.07) girth. In regression models that included weight change as a covariate, none of these differences reached statistical significance. There were no significant differences in weight or girth changes among any of the four active hormone regimens. After accounting for the effects of assignment to active hormone therapy and baseline weight, older age (P 0.008) and higher physical activity level at baseline (P = 0.002) were also independently predictive of less weight gain. The impact of hormone therapy on weight gain was similar among subgroups, except for those defined by baseline smoking status (P = 0.04) and physical activity level at home (P = 0.02). Factors that were independently associated with smaller increases in girths were: for waist, greater overall activity (P = 0.005) and Hispanic ethnicity (P = 0.02); and for hip, work activity (P = 0.003) and greater alcohol consumption (P = 0.03). None of these factors significantly affected the observed overall relationships between estrogen and changes in girth.

Animals↗
PubMed1995

Long-term effects of varying intensities and formats of physical activity on participation rates, fitness, and lipoproteins in men and women aged 50 to 65 years.

BACKGROUND: Although exercise parameters such as intensity and format have been shown to influence exercise participation rates and physiological outcomes in the short term, few data are available evaluating their longer-term effects. The study objective was to determine the 2-year effects of differing intensities and formats of endurance exercise on exercise participation rates, fitness, and plasma HDL cholesterol levels among healthy older adults. METHODS AND RESULTS: Higher-intensity, group-based exercise training; higher-intensity, home-based exercise; and lower-intensity, home-based exercise were compared in a 2-year randomized trial. Participants were 149 men and 120 postmenopausal women 50 to 65 years of age who were sedentary and free of cardiovascular disease. Recruitment was achieved through a random digit-dial community telephone survey and media promotion. All exercise occurred in community settings. For higher-intensity exercise training, three 40-minute endurance training sessions per week were prescribed at 73% to 88% of peak treadmill heart rate. For lower-intensity exercise, five 30-minute endurance training sessions per week were prescribed at 60% to 73% of peak treadmill heart rate. Treadmill exercise performance, lipoprotein levels and other heart disease risk factors, and exercise adherence were evaluated at baseline and across the 2-year period. Treadmill exercise test performance improved for all three training conditions during year 1 and was successfully maintained during year 2, particularly for subjects in the higher-intensity, home-based condition. Subjects in that condition also showed the greatest year 2 exercise adherence rates (P < .003). Although no significant increases in HDL cholesterol were observed during year 1, by the end of year 2 subjects in the two home-based training conditions showed small but significant HDL cholesterol increases over baseline (P < .01). The increases were particularly pronounced for subjects in the lower-intensity condition, whose exercise prescription required more frequent exercise sessions per week. For all exercise conditions, increases in HDL cholesterol were associated with decreases in waist-to-hip ratio in both men and women (P < .04). CONCLUSIONS: While older adults can benefit from initiating a regular regimen of moderate-intensity exercise in terms of improved fitness levels and small improvements in HDL cholesterol levels, the time frame needed to achieve HDL cholesterol change (2 years) may be longer than that reported previously for younger populations. Frequency of participation may be particularly important for achieving such changes. Supervised home-based exercise regimens represent a safe, attractive alternative for achieving sustained participation.

Aged↗
PubMed1995

Rationale, design, and conduct of the PEPI Trial. Postmenopausal Estrogen/Progestin Interventions.

There is growing and consistent evidence that estrogen use in postmenopausal women is associated with a substantial reduction in the occurrence of cardiovascular disease. However, remarkably little is known about the biological mechanisms by which estrogen therapy may influence risk. Even less information is available on the cardiovascular effects of combined estrogen-progestin use. PEPI was not designed to test whether estrogen and estrogen-progestin therapy is efficacious in the prevention of cardiovascular disease, as a much larger trial with clinical disease outcomes is needed to answer that question. However, PEPI will provide critical evidence regarding the potential effectiveness of the various estrogen and estrogen/progestin regimens ni altering risk factors for cardiovascular disease in women. Detailed information on factors such as adherence, side effects, and general patient acceptability will also be ascertained. The main results from PEPI will provide the scientific community with information on the basic actions of estrogen and estrogen/progestin therapy on four biological systems believed to be causally associated with cardiovascular disease occurrence. Further, since the trial is designed to continue for 3 years, PEPI will be able to provide information on longer term as well as short-term effects on these systems. Finally, the results from PEPI should enable women and their physicians to select an optimal hormonal regimen, i.e., one that is acceptable, safe, and provides the most beneficial and least deleterious changes in cardiovascular and other risk factors.

Bone Density↗
PubMed1995

Distribution and correlates of plasma fibrinogen in middle-aged women. Initial findings of the Postmenopausal Estrogen/Progestin Interventions (PEPI) study.

Fibrinogen levels have been reported in cohort and case-control studies to be positively related to the development of coronary heart disease. This report presents the distribution and determinants of fibrinogen in women enrolling in a 3-year randomized trial of hormone replacement therapy (HRT), the Postmenopausal Estrogen/Progestin Interventions (PEPI) trial. Fasting plasma fibrinogen levels were measured in 874 postmenopausal women, aged 45 to 65 years, who had not used HRT for at least 3.5 months. Mean (+/- SD) fibrinogen level was 2.83 +/- 0.45 g/L. There was a significant positive association between fibrinogen and age (P = .03). Significantly higher (P < .005) fibrinogen levels were seen in current smokers versus nonsmokers (2.94 versus 2.81 g/L), in women who reported consuming fewer than 12 alcoholic drinks in the 12 months before the baseline visit versus higher consumption (2.90 versus 2.79 g/L), and in women who reported never versus ever having used HRT (2.90 versus 2.77 g/L). Self-reported leisure time physical activity (LTPA) was negatively associated (P = .0001) with fibrinogen levels as follows: inactive (2.84 g/L), light (2.89 g/L), moderate (2.80 g/L), and heavy (2.60 g/L), with significantly (P = .0001) lower levels in women who reported heavy LTPA versus each of the other categories and in women reporting moderate versus light LTPA. A strong positive correlation was found between fibrinogen and body mass index (BMI) (r = .32; P < .0001). In a model that included age, smoking, alcohol intake, prior HRT, LTPA, and BMI, LTPA was no longer a statistically significant predictor of fibrinogen level, while associations with other variables remained significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Effects of low-fat diet, calorie restriction, and running on lipoprotein subfraction concentrations in moderately overweight men.

We studied the effects of exercise (primarily running), calorie restriction (dieting), and a low-fat, high-carbohydrate diet on changes in lipoprotein subfractions in moderately overweight men in a randomized controlled clinical trial. After 1 year, complete data were obtained for 39 men assigned to lose weight through dieting without exercise, 37 men assigned to lose weight through dieting with exercise (primarily running), and 40 nondieting sedentary controls. We instructed both diet groups to consume no more than 30% total fat, 10% saturated fat, and 300 mg/d of cholesterol, and at least 55% carbohydrates, and the controls were instructed to maintain their usual food choices. Analytic ultracentrifugation was used to measure changes in plasma lipoprotein mass concentrations. In addition, the absorbance of protein-stained polyacrylamide gradient gels was used as an index of concentrations for five high-density lipoprotein (HDL) subclasses that have been identified by their particle sizes, ie, HDL3c (7.2 to 7.8 nm), HDL3b (7.8 to 8.2 nm), HDL3a (8.2 to 8.8 nm), HDL2a (8.8 to 9.7 nm), and HDL2b (9.7 to 12 nm). Relative to controls, weight decreased significantly in men who dieted with exercise (net difference +/- SE, -3.3 +/- 0.4 kg/m2) and in men who dieted without exercise (-2.0 +/- 0.4 kg/m2). Dieting with exercise significantly decreased very-low-density lipoprotein (VLDL)-mass concentrations and significantly increased plasma HDL2-mass, HDL3a, HDL2a, and HDL2b relative to both control and dieting without exercise. There were no significant changes in lipoprotein mass and HDL protein for dieters who did not run.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effects of weight loss by exercise or by dieting on plasma high-density lipoprotein (HDL) levels in men with low, intermediate, and normal-to-high HDL at baseline.

To assess whether baseline plasma high-density lipoprotein (HDL) cholesterol levels affected the HDL response to weight loss, we examined lipoprotein changes in overweight men aged 30 to 59 years who were randomized to lose weight by exercise training (primarily running, n = 46) or by caloric restriction (ie, dieting, n = 42) or to remain sedentary, nondieting controls (n = 42) in a 1-year study. In exercisers, absolute increases in HDL (mg/dL) were greatest in men with normal-to-high baseline HDL and least in men with low baseline HDL. Specifically, when divided into groups of low (< or = 37 mg/dL), intermediate (38 to 47 mg/dL), and normal-to-high HDL cholesterol (> or = 48 mg/dL) at baseline, the exercisers increased HDL cholesterol by 2.3 +/- 1.9, 4.9 +/- 1.1, and 7.0 +/- 1.3 mg/dL, respectively; HDL2 cholesterol by 0.8 +/- 1.6, 2.3 +/- 1.2, and 5.1 +/- 1.3 mg/dL; and HDL2 mass by 2.8 +/- 5.1, 9.5 +/- 8.9, and 31.7 +/- 11.0 mg/dL. Relative increases in HDL cholesterol were more similar in the low (7.1% +/- 6.1%), intermediate (12.4% +/- 3.9%), and normal-to-high men (13.2% +/- 4.0%). Regression analyses were performed to assess whether baseline HDL cholesterol was related to the amount of absolute HDL change per unit of weight loss. In exercisers, the increase in HDL3 cholesterol concentrations was significantly greater in men with low HDL than in those with normal-to-high HDL at entry (2.0 +/- 0.8 v 0.2 +/- 0.8 mg/dL per kg/m2 lost).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Exercise and weight control.

Several important questions need to be answered to increase the likelihood that exercise will be accepted by the millions in the population who are obese. What is the minimum exercise "dose" (intensity, duration, frequency) and what is the optimal mode to bring about substantial fat weight loss, with minimal loss of lean mass? What is the best nutritional plan to optimize fat utilization during exercise, without impairing performance or loss of lean mass? Which diet and exercise programs maximally increase utilization of centrally deposited fat and how can hyperplastic obesity best be treated? Also of interest is the potential role of resistance exercise for weight loss, and the predictors of weight loss success. For instance, do individuals with gynoid obesity really differ from individuals with android obesity in their utilization and loss of body fat during exercise? The potential advantages of exercise include: stimulation of fat as opposed to carbohydrate oxidation; increased energy use during the exercise itself and in the postexercise period; protection of lean body mass; possible reversal of the diet-induced suppression of BMR; and other health benefits. Among other parameters, the effectiveness of exercise on weight loss may be influenced by the type, intensity, frequency, and duration of exercise bouts and the duration of the training program, the nature of the excess fat stores, i.e., whether the person has obesity characterized by hyperplastic or hypertrophic adipose tissue or central (with large-intra-abdominal depot) or peripheral obesity, the composition and caloric content of the diet, and behavioral aspects that affect adherence to the program. With respect to this latter concern, even if a person has been very successful at weight loss in a metabolic ward or intensive program, he/she must eventually return to the outside world and figure out for himself/herself how to eat real food and/or maintain an activity level that promotes weight maintenance. Because diet and exercise habits are difficult to assess and to quantify in free-living populations, it continues to be difficult to evaluate the success of diet and/or exercise prescriptions for weight loss accurately and we continue to be plagued with questions regarding the effectiveness vs. efficacy of exercise as a means to control body weight. It would seem that the wide range of health benefits derived from regular exercise would justify emphasizing increased activity for inactive people, particularly for obese, sedentary individuals, whether or not ideal body weight or significant weight loss is achieved.

Adipose Tissue↗
PubMed1992

Hormones and sexual behavior in relationship to aging in male rats.

To determine if the age-related decline in male sex behavior is correlated with hormonal factors, a longitudinal study was conducted. Sexually experienced males were given mating tests every 2 months from 7 through 27 months of age. To study possible relationships between changes in behavior and alterations in hormone levels, blood samples were taken before and after these bimonthly tests. At 23 months, cross-sectional studies were also conducted comparing results to those obtained in 5-month-old males. Significant changes in mating behavior first appeared at 11 months; mount latency, intromission latency, ejaculation latency, postejaculatory interval, and intercopulatory interval were increased. Similarly, detectable decreases in testosterone (T) also occurred at this age. A significant decline in luteinizing hormone (LH) was not seen until 19 months. Correlational analyses revealed small (r less than or equal to -0.29) but significant negative correlations between T and parameters of mating behavior with age. When each age was examined separately, no significant correlations appeared. Plasma T was not predictive of behavioral performance. At 23 months, cross-sectional studies revealed deficits in mounting and penile reflex behavior but ejaculatory reflex capacity was unimpaired. At 28 months, males were decapitated. Only T levels showed a significant effect of age; estradiol, prolactin, and LH were unaffected when compared to 5-month-old males. The data suggest that although there are small and significant negative correlations between circulating testosterone and parameters of mating behavior with advancing age, it is unlikely that the observed decline in testosterone is the primary cause of the age-induced behavioral deficits. It is likely that the major causal factor(s) involves non-hormone-dependent changes within the CNS.

Aging↗
PubMed1992

Associations of lipoproteins and apolipoproteins with gradient gel electrophoresis estimates of high density lipoprotein subfractions in men and women.

We examined the relations of gender and lipoproteins to subclasses of high density lipoproteins (HDLs) in a cross-sectional sample of moderately overweight men (n = 116) and women (n = 78). The absorbance of protein-stained polyacrylamide gradient gels was used as an index of mass concentrations of HDL at intervals of 0.01 nm across the entire HDL particle size range (7.2-12 nm). At least five HDL subclasses have been identified by their particle sizes: HDL3c (7.2-7.8 nm), HDL3b (7.8-8.2 nm), HDL3a (8.2-8.8 nm), HDL2a (8.8-9.7 nm), and HDL2b (9.7-12 nm). Men had significantly higher HDL3b and significantly lower HDL2a and HDL2b than did women. Correlations of HDL subclasses with concentrations of other lipoprotein variables were generally as strong for gradient gel electrophoresis as for analytical ultracentrifugation measurements of HDL particle distributions. In both sexes, high levels of HDL3b were associated with coronary heart disease risk factors, including high concentrations of triglycerides, apolipoprotein B, small low density lipoproteins, intermediate density lipoproteins, and very low density lipoproteins and low concentrations of HDL2 cholesterol and HDL2 mass. Plasma concentrations of HDL3 cholesterol were unrelated to protein-stained HDL3b levels. HDL3 cholesterol concentrations also did not exhibit the sex difference or the relations with lipoprotein concentrations that characterized HDL3b. Thus, low HDL3b levels may contribute in part to the low heart disease risk in men and women who have high HDL cholesterol. Measurements of HDL3 cholesterol may not identify clinically important relations involving HDL3b.

Adult↗