Responses to LBNP in men with varying profiles of strength and aerobic capacity: Implications for flight crews

Hemodynamic and hormonal responses to lower-body negative pressure (LBNP) were examined in 24 healthy men to test the hypothesis that responsiveness of reflex control of blood pressure during orthostatic stress is associated with strength and/or aerobic capacity. Subjects underwent treadmill tests to determine peak oxygen uptake (peak VO2) and isokinetic dynamo meter tests to determine leg strength. Based on predetermined criteria, the subjects were classified into one of four fitness profiles of six subjects each matched for age, height, and weight: (1) low strength/low aerobic fitness; (2) low strength/high aerobic fitness; (3) high strength/low aerobic fitness; and (4) high strength/high aerobic fitness. Following 90 min of 6 degree head-down tilt (HDT), each subject underwent graded LBNP through -50 mmHg or presyncope, with maximal duration 15 min. All groups exhibited typical hemodynamic, hormonal, and fluid shift responses during LBNP, with no intergroup differences except for catecholamines. Seven subjects, distributed among the four fitness profiles, became presyncopal. Subjects who showed greatest reduction in mean arterial pressure (MAP) during LBNP had greater elevations in vasopressin and lesser increases in heart rate and peripheral resistance. Peak VO2 nor leg strength were correlated with fall in MAP or with syncopal episodes. We conclude that neither aerobic nor strength fitness characteristics are good predictors of responses to LBNP stress

The relationship of circulating dehydroepiandrosterone, testosterone, and estradiol to stages of the menopausal transition and ethnicity

In this report, 3029 women between the ages of 42 and 54 yr from five ethnic groups were studied for 2 yr. Log circulating dehydroepiandrosterone sulfate (DHEAS) concentrations were highest among Chinese and Japanese and lowest among African Americans and Hispanics, and this pattern persisted after adjustment for age, smoking, and log body mass index (BMI). With the exception of Japanese women, log BMI was negatively related to log circulating DHEAS. The magnitude of this association varied by ethnic group, and the decline in log circulating DHEAS levels with higher log BMI was steepest for Chinese and least steep for Hispanics. The relationship between log DHEAS and log BMI was positive for Japanese. DHEAS levels did not decline at a steady rate during the menopausal transition and transiently increased in some women and increased, on average, during the transition to late perimenopause. These increases tended to be larger for Chinese, Hispanic, and Japanese than for African Americans and Caucasians, although the interactions were not statistically significant. Changes in circulating testosterone and, to a lesser extent, estradiol were correlated to changes in DHEAS. These data have importance in understanding the endocrinology of the menopausal transition, defining the relationship of adrenal steroid production during declining ovarian function and determining a rationale regarding DHEAS supplementation for older women

Dietary fat subgroups, zinc, and vegetable components are related to urine F2a-isoprostane concentration, a measure of oxidative stress, in midlife women

Smoking, diet, and physical activity may impact chronic diseases in part by promoting or attenuating oxidative stress. We evaluated associations between lifestyle factors and urine F(2a)-isoprostanes, a marker of oxidative stress in 1610 participants of the Study of Women\u27s Health Across the Nation (SWAN). Dietary intake and physical activity were assessed at baseline and the 5th year 05 (Y05). These data were related to Y05 urinary F(2a)-isoprostane concentration with regression analyses. Median urine F(2a)-isoprostane concentration was 433 ng/L overall, 917 ng/L in smokers [inter-quartile range (IQR): 467, 1832 ng/L], and 403 ng/L in nonsmokers (IQR: 228, 709 ng/L; P \u3c 0.0001 for difference). Higher trans fat intake was associated with higher urine F(2a)-isoprostane concentration; partial Spearman correlations (rho(x|y)) between Y05 urine F(2a)-isoprostane concentration and trans fatty acids was 0.19 (P = 0.03) in smokers and 0.13 (P \u3c 0.0001) in nonsmokers. Increased log trans fat intake from baseline to Y05 was associated with higher concentration of log urine F(2a)-isoprostanes in nonsmokers (beta = 0.131, SE = 0.04, P = 0.0003). In nonsmokers, the partial correlation (rho(x|y)) between lutein and urine F(2a)-isoprostane concentration was -0.13 (P \u3c 0.0001). Increased intake of log lutein from baseline to Y05 was also associated with lower log urine F(2a)-isoprostane concentration (beta = -0.096, SE = 0.03, P = 0.0005) in nonsmokers. Increased zinc intake from baseline to Y05 was associated with lower log urine F(2a)-isoprostane concentration in smokers and nonsmokers (beta = -0.346, SE = 0.14, P = 0.01), and -0.117, 0.04 (P = 0.001), respectively]. In conclusion, diet (fat subtypes, zinc, and vegetable components) and smoking were associated with urine F(2a)-isoprostanes, a marker of oxidative stress

Correlates of circulating androgens in mid-life women: the study of women\u27s health across the nation

CONTEXT: Androgens influence sexual differentiation and behavior, body composition, and physical functioning in men, but their role in women is less well understood. Because circulating androgens decline with age, the use of androgen supplementation for women to improve health and well-being has been increasing. OBJECTIVE: The aim of this study was to assess the association between androgens and a variety of end points thought to be affected by androgens. DESIGN: In a community-based baseline cohort of women aged 42-52 yr from the Study of Women\u27s Health Across the Nation, we measured circulating testosterone (T), dehydroepiandrosterone sulfate, and SHBG, and calculated a free androgen index (FAI) in 2961 women. MAIN OUTCOME MEASURES: Correlations of androgen measures with each other and with body mass index, waist circumference, and waist-hip ratio were computed, and odds ratios (OR) were estimated for the categorical outcomes of functional limitations, functional status, self-reported health, scores indicative of depressed mood, quality of life, sexual desire and arousal, and the presence of the metabolic syndrome. RESULTS: Androgens, and particularly SHBG, were associated most strongly with body mass index, waist circumference, and waist-hip ratio. SHBG was associated prominently inversely with the metabolic syndrome (OR = 0.32; 95% confidence interval = 0.26-0.39), which was present in 17% of women at baseline. Dehydroepiandrosterone sulfate was associated modestly with functional status and self-reported health. T was associated minimally with increased sexual desire (OR = 1.09; 95% confidence interval = 1.00-1.18). The association of FAI with self-reported health and depressive symptomatology based on the Center for Epidemiologic Studies Depression Scale score was explained more by T than by SHBG, whereas the association of FAI with sexual arousal and metabolic syndrome was due more to SHBG than to T. CONCLUSIONS: Circulating SHBG and androgens are most strongly associated with physical characteristics and the metabolic syndrome in women in this community-based cohort. Androgens are related weakly to physical functioning and other symptoms to which they commonly are attributed, such as sexual desire, sexual arousal, and well-being

Circulating dehydroepiandrosterone sulfate concentrations during the menopausal transition

CONTEXT: A previous report from the Study of Women Across the Nation indicated a rise in dehydroepiandrosterone sulfate (DHEAS) during the menopausal transition using data from three annual visits. OBJECTIVE: Our objective was to examine changes in DHEAS with chronological and ovarian aging, expanding the original analyses to include 10 yr of annual data. DESIGN: A longitudinal observational study and cross-sectional analyses of baseline data were conducted. OUTCOME MEASURES AND SUBJECTS: DHEAS, age, menopause status, ethnicity, smoking, weight, and height were assessed in 2886 women from five ethnic groups aged 42-52 yr at entry. Hysterectomy, bilateral oophorectomy, and hormone use were excluded. RESULTS: Cross-sectional analysis at baseline showed a linear decline in circulating log-transformed DHEAS with increasing age for either the entire cohort (2.81% per year) or for individual ethnicities. A similar negative association with baseline age (2.44% decline per year) was seen in longitudinal linear mixed modeling including observations from premenopause through late postmenopause, an additional 0.33% decline/year. In contradistinction, a late-transition rise in DHEAS was detected when the same women were analyzed by ovarian status. The average increase in mean circulating DHEAS level between early and late menopause transition, beyond changes predicted by aging, was 3.95%, followed by an average decline of 3.96% during the late postmenopause. Approximately 84.5% of the women had an estimated within-woman increase in DHEAS from premenopause/early perimenopause to late perimenopause/early postmenopause. CONCLUSION: These observations underscore differences between cross-sectional and longitudinal studies and the importance of considering ovarian status. Additional investigations regarding adrenal contribution to sex steroids in mid-aged women are warranted

Body size and ethnicity are associated with menstrual cycle alterations in women in the early menopausal transition: The Study of Women\u27s Health across the Nation (SWAN) Daily Hormone Study

The dynamics of reproductive hormones that characterize the menopausal transition (perimenopause) are incompletely understood, particularly in non-Caucasian women. The Study of Women\u27s Health across the Nation (SWAN) is a multiethnic cohort study of 3302 women at seven sites who were aged 42-52 yr at baseline. All participants are seen annually to assess a variety of endpoints. A subcohort of 848 women undergoes further investigation of their daily patterns of reproductive hormones in the Daily Hormone Study (DHS). DHS enrollees annually complete a daily collection of first morning voided urine for an entire menstrual cycle or up to 50 d (whichever comes first). Chemiluminescent assays measured urinary LH and FSH, as well as metabolites of estradiol [estrone conjugates (E1c)] and progesterone [pregnanediol glucuronide (Pdg)]. Cycles were assessed for evidence of luteal activity and day of luteal transition using previously developed algorithms. Midreproductive-aged women who underwent similar daily urinary analyses served as historical controls. Correlates of cycle features were identified. Eight hundred thirty-three cycles were evaluable and had complete data on covariates. Six hundred seventy-four (80.9%) cycles had evidence of luteal activity, and 159 (19.1%) did not. Women who were at least 49 yr old were less likely to have cycles with luteal activity and had more variable cycle length, higher total-cycle FSH, and lower total-cycle Pdg. Compared with heavier women, those with body mass index less than 25 kg/m2 had shorter cycles and higher total-cycle LH, FSH, and Pdg but not E1c. Chinese- and Japanese-American women had overall lower adjusted total-cycle E1c excretion. Smoking was not significantly associated with cycle length or hormones. When compared with cycles of younger control women, the cycles of the SWAN DHS participants had higher gonadotropins, lower total integrated Pdg, and E1c levels that were not different, which suggests that the ovary retains sensitivity to elevated FSH in the early menopausal transition. In this cross-sectional study of women over age 42 who are premenopausal or in the early menopausal transition, there were important differences in the characteristics of cycles related to age, body mass index, and ethnicity. Comparisons to younger women indirectly support the inhibin hypothesis, which proposes that the initiating event in the menopausal transition is the loss of inhibin negative feedback on FSH secondary to a diminished follicular reserve