Habitual physical activity (HPA) as a factor in sustained executive function in Alzheimer-type dementia: a cohort study

Evidence from studies on healthy older adults and mild cognitive impairment (MCI) populations suggests that physical activity interventions have a positive effect on executive function. In this study, we consider whether HPA is positively associated with executive function in Alzheimer's disease (AD). Eighty-two participants with a diagnosis of mild to moderate AD completed six measures of executive function. Objective measures of physical status were taken. In addition, informants completed questionnaires on the participants’ HPA and other lifestyle factors. A composite measure of executive function was the primary outcome. A multistage multiple regression was used to determine how much variance HPA accounted for. The final model comprised disease severity, cognitive reserve, cognitive activities, neuropsychiatric status and HPA status. The final model accounted for a total of 57% of the variance of executive performance, of which HPA itself accounted for 8% of the variance. HPA status is associated executive performance in an AD population even after controlling for key covariates. The findings encourage clinicians to recommend HPA and its cognitive benefits to AD patients and their carers

Effects of intrauterine exposure to synthetic glucocorticoids on fetal, newborn, and infant hypothalamic-pituitary-adrenal axis function in humans : a systematic review

BACKGROUND: Synthetic glucocorticoids are commonly used in reproductive medicine. Fetal organ systems are highly sensitive to changes in the intrauterine environment, including overexposure to glucocorticoids. Structural and functional alterations resulting from such changes may persist throughout life and have been associated with diverse diseases. One system that could be particularly sensitive to fetal glucocorticoid overexposure is the hypothalamic-pituitary-adrenal (hpa) axis. Many human studies have investigated this possibility, but a systematic review to identify consistent, emergent findings is lacking. METHODS: We systematically review 49 human studies, assessing the effects of intrauterine exposure to synthetic glucocorticoids on fetal, neonate, and infant hpa function. RESULTS: Study quality varied considerably, but the main findings held true after restricting the analyses to higher-quality studies: intrauterine exposure to synthetic glucocorticoids reduces offspring hpa activity under unstimulated conditions after pain but not pharmacological challenge. Although reduced unstimulated hpa function appears to recover within the first 2 wk postpartum, blunted hpa reactivity to pain is likely to persist throughout the first 4 months of life. There is some evidence that the magnitude of the effects is correlated with the total amount of glucocorticoids administered and varies with the time interval between glucocorticoid exposure and hpa assessment. CONCLUSIONS: This systematic review has allowed the demonstration of the way in which intrauterine exposure to various regimens of synthetic glucocorticoids affects various forms of hpa function. As such, it guides future studies in terms of which variables need to be focused on in order to further strengthen the understanding of such therapy, whilst continuing to profit from its clinical benefits

Leptin fails to blunt the lipopolysaccharide-induced activation of the hypothalamic-pituitary-adrenal axis in rats

Copyright @ 2013 The authors. This work is licensed under a Creative Commons Attribution 3.0 Unported License.Obesity is a risk factor for sepsis morbidity and mortality, whereas the hypothalamic-pituitary-adrenal (HPA) axis plays a protective role in the body's defence against sepsis. Sepsis induces a profound systemic immune response and cytokines serve as excellent markers for sepsis as they act as mediators of the immune response. Evidence suggests that the adipokine leptin may play a pathogenic role in sepsis. Mouse endotoxaemic models present with elevated leptin levels and exogenously added leptin increased mortality whereas human septic patients have elevated circulating levels of the soluble leptin receptor (Ob-Re). Evidence suggests that leptin can inhibit the regulation of the HPA axis. Thus, leptin may suppress the HPA axis, impairing its protective role in sepsis.We hypothesised that leptin would attenuate the HPA axis response to sepsis.We investigated the direct effects of an i.p. injection of 2 mg/kg leptin on the HPA axis response to intraperitoneally injected 25 μg/kg lipopolysaccharide (LPS) in the male Wistar rat. We found that LPS potently activated the HPA axis, as shown by significantly increased plasma stress hormones, ACTH and corticosterone, and increased plasma interleukin 1β (IL1β) levels, 2 h after administration. Pre-treatment with leptin, 2 h before LPS administration, did not influence the HPA axis response to LPS. In turn, LPS did not affect plasma leptin levels. Our findings suggest that leptin does not influence HPA function or IL1b secretion in a rat model of LPS-induced sepsis, and thus that leptin is unlikely to be involved in the acute-phase endocrine response to bacterial infection in rats.The section is funded by grants from the MRC, BBSRC, NIHR and an Integrative Mammalian Biology (IMB) Capacity Building Award, and by a FP7-HEALTH-2009-241592 EuroCHIP grant and is supported by the NIHR Imperial Biomedical Research Centre Funding Scheme. This work is supported by a BBSRC Doctoral Training-Strategic Skills Award grant (BB/F017340/1)

Acute effects of inspiratory pressure threshold loading upon airway resistance in people with asthma

This is the post-print version of the final paper published in Respiratory Physiology & Neurobiology. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2009 Elsevier B.V.Large inspiratory pressures may impart stretch to airway smooth muscle and modify the response to deep inspiration (DI) in asthmatics. Respiratory system resistance (Rrs) was assessed in response to 5 inspiratory manoeuvres using the forced oscillation technique: (a) single unloaded DI; (b) single DI at 25 cmH2O; (c) single DI at 50% maximum inspiratory mouth pressure [MIP]; (d) 30 DIs at 50% MIP; and (e) 30 DIs at 50% MIP with maintenance of normocapnia. Rrs increased after the unloaded DI and the DI at 25 cmH2O but not after a DI at 50% MIP (3.6 ± 1.6 hPa L s−1 vs. 3.6 ± 1.5 hPa L s−1; p = 0.95), 30 DIs at 50% MIP (3.9 ± 1.5 hPa L s−1 vs. 4.2 ± 2.0 hPa L s−1; p = 0.16) or 30 DIs at 50% MIP under normocapnic conditions (3.9 ± 1.5 hPa L s−1 vs. 3.9 ± 1.5 hPa L s−1; p = 0.55). Increases in Rrs in response to DI were attenuated after single and multiple loaded breaths at 50% MIP

Validation of Aura Microwave Limb Sounder O-3 and CO observations in the upper troposphere and lower stratosphere

International audienceGlobal satellite observations of ozone and carbon monoxide from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed with emphasis on those observations in the 215–100 hPa region (the upper troposphere and lower stratosphere). The precision, resolution and accuracy of the data produced by the MLS “version 2.2” processing algorithms are discussed and quantified. O3 accuracy is estimated at ~40 ppbv +5% (~20 ppbv +20% at 215 hPa) while the CO accuracy is estimated at ~30 ppbv +30% for pressures of 147 hPa and less. Comparisons with expectations and other observations show good agreements for the O3 product, generally consistent with the systematic errors quoted above. In the case of CO, a persistent factor of ~2 high bias is seen at 215 hPa. However, the morphology is shown to be realistic, consistent with raw MLS radiance data, and useful for scientific study. The MLS CO data at higher altitudes are shown to be consistent with other observations

Stratospheric Variability and Trends in Models Used for the IPCC AR4

Atmosphere and ocean general circulation model (AOGCM) experiments for the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) are analyzed to better understand model variability and assess the importance of various forcing mechanisms on stratospheric trends during the 20th century. While models represent the climatology of the stratosphere reasonably well in comparison with NCEP reanalysis, there are biases and large variability among models. In general, AOGCMs are cooler than NCEP throughout the stratosphere, with the largest differences in the tropics. Around half the AOGCMs have a top level beneath ~2 hPa and show a significant cold bias in their upper levels (~10 hPa) compared to NCEP, suggesting that these models may have compromised simulations near 10 hPa due to a low model top or insufficient stratospheric levels. In the lower stratosphere (50 hPa), the temperature variability associated with large volcanic eruptions is absent in about half of the models, and in the models that do include volcanic aerosols, half of those significantly overestimate the observed warming. There is general agreement on the vertical structure of temperature trends over the last few decades, differences between models are explained by the inclusion of different forcing mechanisms, such as stratospheric ozone depletion and volcanic aerosols. However, even when human and natural forcing agents are included in the simulations, significant differences remain between observations and model trends, particularly in the upper tropical troposphere (200 hPa–100 hPa), where, since 1979, models show a warming trend and the observations a cooling trend

Impact of Gene-Gender Effects of Adrenergic Polymorphisms on Hypothalamic-Pituitary-Adrenal Axis Activity in Depressed Patients

Objective: There is overwhelming evidence that activation of the hypothalamic-pituitary-adrenal (HPA) system plays a major role in depression and cardiovascular disease in genetically susceptible individuals. We hypothesized that due to the multiple interactions between the sympathetic and the HPA systems via adrenoceptors, polymorphisms in these genes could have an impact on HPA axis activity in major depression. Methods: Using the dexamethasone/corticotrophin-releasing hormone (DEX/CRH) test, we investigated the association of alpha 2-adrenoceptor (ADRA2A -1291C -> G) and the beta 2-adrenoceptor gene (ADRB2 Arg16Gly) in 189 patients with major depression during the acute state of the disease and after remission. Results: Male ADRA2A -1291G allele homozygotes showed significant pretreatment HPA axis hyperactivity, with increased adrenocorticotropin (ACTH; F = 4.9, d.f. = 2, p = 0.009) and cortisol responses (F = 6.4, d.f. = 2, p = 0.003). In contrast, female ADRB2 Arg/Arg homozygotes had increased pretreatment ACTH (F = 7.17, d.f. = 2, p = 0.001) and cortisol (F = 8.95, d.f. = 2, p = 0.000) levels. Interestingly, in the respective genotypes, the stress hormones remained elevated in the second DEX/CRH test, despite a reduction in depressive symptoms. Conclusions: This study provides evidence that, depending on gender and polymorphisms, there is continuous HPA axis overdrive in a proportion of patients irrespective of the status of depression. Considering the importance of stress hormones for cardiovascular disorders, our data might suggest that these patients are at high risk of comorbidity between depression and cardiovascular disorders. Copyright (c) 2008 S. Karger AG, Base

Atmospheric temperature tides in the tropical upper troposphere and lower stratosphere

Atmospheric thermal tides are global-scale waves with periods that are harmonics of a solar day, mainly excited by diurnally varying diabatic heating in the troposphere and the stratosphere. Some recent studies suggested that the tidal temperature variations in the TTL might affect the appearance of cirrus clouds and, thus, the dehydration process. It should be noted, however, that the global pattern of diurnal temperature variations in the TTL still remains unclear. In this study, we aim at revealing the 3D structure of diurnal temperature variations around the TTL, including its seasonal variations, by using data from global reanalyses for the period of 2002-2006. It is found that the Sun synchronous tides have amplitudes of ~0.3 K (~0.5 K) at 100 hPa (70 hPa) in January. Superposed on these components, the non-Sun-synchronous tides are strong over the continent (South America, Africa); these may be excited by latent heat release associated with deep convections there. The total (i.e., Sun-synchronous plus non-Sun-synchronous) diurnal temperature amplitudes reach ~0.5 K (~1 K) at maxima at 100 hPa (70 hPa) in January. The seasonality and the impact on the dehydration will be discussed in the presentation

Orbiter based construction equipment

Many orbiter based activities need equipment to hold a payload steady while it is being worked on. This work may be construction, updating, repair, services, check out, or refueling operations in preparation for return to Earth. The Handling and Positioning Aid (HPA) is intended for use as general purpose equipment. The HPA provides a wide choice of work station positions, both immediately above the orbiter cargo bay and beyond. It can act in a primary docking role and, if required, can assist actively in the berthing process. From an analysis of ten reference missions, it was determined that two types of HPA mobility are needed; a tilt table, which simply swings out of the cargo bay, pivoting about an athwartships y axis, and an articulated arm. Illustration of the aid are provided