Menstrual cycle phase effects free testosterone responses to prolonged aerobic exercise

Research has shown that total testosterone (tT) levels in women increase acutely during a prolonged bout of aerobic exercise. Few studies, however, have considered the impact of the menstrual cycle phase on this response or have looked at the biologically active free testosterone (fT) form responses. Therefore, this study examined the fT concentration response independently and as a percentage (fT%) of tT to prolonged aerobic exercise during phases of the menstrual cycle with low estrogen-progesterone (L-EP; i.e., follicular phase) and high estrogen-progesterone (H-EP; i.e., luteal phase). Ten healthy, recreationally trained, eumennorrheic women (X ± SD: age = 20 ± 2 y, mass = 58.7 ± 8.3 kg, body fat = 22.3 ± 4.9 %, VO2max = 50.7 ± 9.0 ml/kg/min) participated in a laboratory based study and completed a 60-minute treadmill run during the L-EP and H-EP menstrual phases at ~70% of VO2max. Blood was drawn prior to (PRE), immediately after (POST) and following 30 minutes of recovery (30POST) with each 60-minute run. During H-EP, there was a significant increase in fT concentrations from PRE to POST (p < 0.01) while in L-EP fT levels were unchanged; which resulted in fT being significantly higher at H-EP POST versus L-EP POST (p < 0.03). Area-under-the-curve (AUC) responses were calculated, for fT the total AUC was greater in H-EP than L-EP (p < 0.04). There was no significant interaction of fT% between phases and exercise sampling time. There was, however, a main effect for exercise where fT% POST was a greater proportion of tT than at PRE (p < 0.01). In summary, hormonal changes associated with the menstrual cycle impact fT response to a prolonged aerobic exercise bout; specifically, there being higher levels under H-EP conditions. This suggests more biologically active T is available during exercise in this phase. This response may be a function of the higher core temperatures found with H-EP causing greater sex hormone binding protein release of T, or could be a function of greater degrees of glandular production. Further work is warranted to elucidate the mechanism of this occurrence. It is recommended that researchers examining T responses to exercise in women look at both tT and fT forms in order to have an accurate endocrine assessment in women

Perturbation of hyaluronan metabolism predisposes patients with type 1 diabetes mellitus to atherosclerosis

AIMS/HYPOTHESIS: Cardiovascular disease contributes to mortality in type 1 diabetes mellitus, but the specific pathophysiological mechanisms remain to be established. We recently showed that the endothelial glycocalyx, a protective layer of proteoglycans covering the endothelium, is severely perturbed in type 1 diabetes, with concomitantly increased plasma levels of hyaluronan and hyaluronidase. In the present study, we evaluated the relationship between hyaluronan and hyaluronidase with carotid intima-media thickness (cIMT), an established surrogate marker for cardiovascular disease. SUBJECTS AND METHODS: Non-smoking type 1 diabetes patients without micro- or macrovascular complications and matched controls were recruited and cIMT of both carotid arteries was measured. To evaluate the relationship between cIMT and hyaluronan and hyaluronidase as well as other parameters, uni- or multivariate regression analyses were performed. RESULTS: We included 99 type 1 diabetes patients (age 10-72 years) and 99 age- and sex-matched controls. Mean cIMT, HbA(1c), high sensitivity C-reactive protein, hyaluronan and hyaluronidase were significantly increased in type 1 diabetes vs controls. Plasma hyaluronan and hyaluronidase were correlated in type 1 diabetes. In univariate regression analyses, mean IMT was associated with plasma hyaluronan, age and male sex, whereas after multivariate analysis only age and sex remained statistically significant. CONCLUSIONS/INTERPRETATION: We conclude that type 1 diabetes patients show structural changes of the arterial wall associated with increased hyaluronan metabolism. These data may lend further support to altered glycosaminoglycan metabolism in type 1 diabetes as a potential mechanism involved in accelerated atherogenesi

Firsthand Experience and The Subsequent Role of Reflected Knowledge in Cultivating Trust in Global Collaboration

While scholars contend that firsthand experience - time spent onsite observing the people, places, and norms of a distant locale - is crucial in globally distributed collaboration, how such experience actually affects interpersonal dynamics is poorly understood. Based on 47 semistructured interviews and 140 survey responses in a global chemical company, this paper explores the effects of firsthand experience on intersite trust. We find firsthand experience leads not just to direct knowledge of the other, but also knowledge of the self as seen through the eyes of the other - what we call “reflected knowledge”. Reflected and direct knowledge, in turn, affect trust through identification, adaptation, and reduced misunderstandings

Environmental regulation of carbon isotope composition and crassulacean acid metabolism in three plant communities along a water availability gradient

Expression of crassulacean acid metabolism (CAM) is characterized by extreme variability within and between taxa and its sensitivity to environmental variation. In this study, we determined seasonal fluctuations in CAM photosynthesis with measurements of nocturnal tissue acidification and carbon isotopic composition (δ13C) of bulk tissue and extracted sugars in three plant communities along a precipitation gradient (500, 700, and 1,000 mm year−1) on the Yucatan Peninsula. We also related the degree of CAM to light habitat and relative abundance of species in the three sites. For all species, the greatest tissue acid accumulation occurred during the rainy season. In the 500 mm site, tissue acidification was greater for the species growing at 30% of daily total photon flux density (PFD) than species growing at 80% PFD. Whereas in the two wetter sites, the species growing at 80% total PFD had greater tissue acidification. All species had values of bulk tissue δ13C less negative than −20‰, indicating strong CAM activity. The bulk tissue δ13C values in plants from the 500 mm site were 2‰ less negative than in plants from the wetter sites, and the only species growing in the three communities, Acanthocereus tetragonus (Cactaceae), showed a significant negative relationship between both bulk tissue and sugar δ13C values and annual rainfall, consistent with greater CO2 assimilation through the CAM pathway with decreasing water availability. Overall, variation in the use of CAM photosynthesis was related to water and light availability and CAM appeared to be more ecologically important in the tropical dry forests than in the coastal dune

A Cost-Utility Analysis of Prostate Cancer Screening in Australia

Background and Objectives: The Göteborg randomised population-based prostate cancer screening trial demonstrated that Prostate Specific Antigen (PSA) based screening reduces prostate cancer deaths compared with an age matched control group. Utilising the prostate cancer detection rates from this study we have investigated the clinical and cost-effectiveness of a similar PSA-based screening strategy for an Australian population of men aged 50-69 years. Methods: A decision model that incorporated Markov processes was developed from a health system perspective.The base case scenario compared a population-based screening programme with current opportunistic screening practices. Costs, utility values, treatment patterns and background mortality rates were derived from Australian data. All costs were adjusted to reflect July 2015 Australian dollars. An alternative scenario compared systematic with opportunistic screening but with optimisation of active surveillance (AS) uptake in both groups. A discount rate of 5% for costs and benefits was utilised. Univariate and probabilistic sensitivity analyses were performed to assess the effect of variable uncertainty on model outcomes. Results: Our model very closely replicated the number of deaths from both prostate cancer and background mortality in the Göteborg study. The incremental cost per quality-adjusted life-year (QALY) for PSA screening was $AU147,528. However, for years of life gained (LYGs) PSA based screening ($AU45,890/LYG) appeared more favourable. Our alternative scenario with optimised AS improved cost-utility to $AU45,881/QALY, with screening becoming cost-effective at a 92$AU50,000/QALY. It appears more cost-effective if LYGs are used as the relevant outcome, and is more cost effective than the established Australian breast cancer screening programme on this basis. Optimised utilisation of AS increases the cost-effectiveness of prostate cancer screening dramatically

Sex Differences in Dietary Intake in British Army Recruits undergoing Phase One training

Background: British Army Phase One training exposes men and women to challenging distances of 13.5 km·d⁻¹ vs. 11.8 km·d⁻¹ and energy expenditures of ~4000 kcal·d⁻¹ and ~3000 kcal·d⁻¹, respectively. As such, it is essential that adequate nutrition is provided to support training demands. However, to date, there is a paucity of data on habitual dietary intake of British Army recruits. The aims of this study were to: (i) compare habitual dietary intake in British Army recruits undergoing Phase One training to Military Dietary Reference Values (MDRVs), and (ii) establish if there was a relative sex difference in dietary intake between men and women. Method: Researcher led weighed food records and food diaries were used to assess dietary intake in twenty-eight women (age 21.4 ± 3.0 yrs., height: 163.7 ± 5.0 cm, body mass 65.0 ± 6.7 kg), and seventeen men (age 20.4 ± 2.3 yrs., height: 178.0 ± 7.9 cm, body mass 74.6 ± 8.1 kg) at the Army Training Centre, Pirbright for 8-days in week ten of training. Macro and micronutrient content were estimated using dietary analysis software (Nutritics, Dublin) and assessed via an independent sample t-test to establish if there was a sex difference in daily energy, macro or micronutrient intakes. Results: Estimated daily energy intake was less than the MDRV for both men and women, with men consuming a greater amount of energy compared with women (2846 ± 573 vs. 2207 ± 585 kcal·day⁻¹, p0.030, ES=0.67). There were no differences in dietary fat intake between men and women (1.5 ± 0.2 vs. 1.5 ± 0.5 g·kg⁻¹·day⁻¹, p=0.483, ES=0.00). Conclusions: Daily EI in men and women in Phase One training does not meet MDRVs. Interventions to increase macronutrient intakes should be considered along with research investigating the potential benefits for increasing different macronutrient intakes on training adaptations

Preterm birth and small for gestational age in relation to alcohol consumption during pregnancy: stronger associations among vulnerable women? Results from two large Western-European studies

Pfinder M, Kunst AE, Feldmann R, van Eijsden M, Vrijkotte TGM. Preterm birth and small for gestational age in relation to alcohol consumption during pregnancy: stronger associations among vulnerable women? Results from two large Western-European studies. BMC Pregnancy and Childbirth. 2013;13(1): 49.BACKGROUND: Inconsistent data on the association between prenatal alcohol exposure and a range of pregnancy outcomes, such as preterm birth (PTB) and small for gestational age (SGA) raise new questions. This study aimed to assess whether the association between low-moderate prenatal alcohol exposure and PTB and SGA differs according to maternal education, maternal mental distress or maternal smoking. METHODS: The Amsterdam Born Children and their Development (ABCD) Study (N=5,238) and the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) (N=16,301) are both large studies. Women provide information on alcohol intake in early pregnancy, 3 months postpartum and up to 17 years retrospectively. Multivariate logistic regression analyses and stratified regression analyses were performed to examine the association between prenatal alcohol exposure and PTB and SGA, respectively. RESULTS: No association was found between any level of prenatal alcohol exposure (non-daily, daily, non-abstaining) and SGA. The offspring of daily drinkers and non-abstainers had a lower risk of PTB [ABCD: odds ratio (OR) 0.31, 95% confidence interval (CI) 0.13, 0.77; KiGGS: OR 0.75, 95% CI 0.57, 0.99]. Interactions with maternal education, maternal distress or maternal smoking were not significant. CONCLUSIONS: Although these results should be interpreted with caution, both studies showed no adverse effects of low-moderate prenatal alcohol exposure on PTB and SGA, not even in the offspring of women who were disadvantaged in terms of low education, high levels of distress, or smoking during pregnancy