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Cerebrovascular function and cognition decline with age and are further exacerbated by obesity and physical inactivity. This decline may be offset by aerobic exercise training (AT). We investigated the effects of 16 weeks AT on cerebrovascular and cognitive function in sedentary, obese, older adults. Twenty-eight participants were randomly allocated to AT or a control group. Before and after the intervention, transcranial Doppler ultrasonography was used to measure the cerebrovascular responsiveness (CVR) to physiological (hypercapnia, 5% carbon dioxide) and cognitive stimuli. AT increased the CVR to hypercapnia (98.5 ± 38.4% vs. 58.0 ± 42.0%, P = 0.021), CVR to cognitive stimuli (25.9 ± 6.1% vs. 16.4 ± 5.4%, P < 0.001) and total composite cognitive score (111 ± 14 vs. 104 ± 14, P = 0.004) compared with the control group. A very strong relationship was observed between the number of exercise sessions completed and CVR to cognitive stimuli (r = 0.878, P < 0.001), but not for CVR to hypercapnia (r = 0.246, P = 0.397) or total composite cognitive score (r = 0.213, P = 0.465). Cerebrovascular function and cognition improved following 16 weeks of AT and a dose-response relationship exists between the amount of exercise sessions performed and CVR to cognitive stimuli. [ABSTRACT FROM AUTHOR]

Background: High concentration oxygen therapy in hypercapnic chronic obstructive pulmonary disease (COPD) is associated with increased mortality. In ward‐based patients with acute exacerbation of COPD and hypercapnia, this study examines oxygen prescription and the association between high concentration oxygen therapy and adverse outcome. Aims: To investigate the association between over‐oxygenation and in‐hospital adverse events. Methods: Inpatients with acute exacerbation of hypercapnic COPD at a tertiary Australian hospital over a 1‐year period were retrospectively identified. Oxygen prescription and therapy was determined based on chart review. Over‐oxygenation was defined as ≥10% of nursing chart observations recording oxygen delivery with oxygen saturation above 92%. A composite adverse outcome was defined as medical emergency team response, recommencement of non‐invasive ventilation or death. The association between over‐oxygenation and adverse outcome was assessed using survival analysis and conditional logistic regression modelling. Results: The study cohort comprised 106 unique patients and 157 admissions. Oxygen prescription was recorded in 132 (84%) and over‐oxygenation occurred in 97 (62%) admissions. Over‐oxygenation was higher in non‐respiratory ward admissions (76% vs 57%, P = 0.03) and those without any form of oxygen prescription (84% vs 58%, P = 0.01). During follow up, 23 (22%) patients experienced an adverse event. Cox proportional hazards modelling found weak evidence for increased risk of an adverse event in over‐oxygenated patients (hazard ratio 2.5; 95% confidence interval 0.8–7.3, P = 0.10). Conditional logistic regression, after matching on age, Charlson comorbidity category and length of follow up, found a similar estimate of association (hazard ratio 2.6; 95% confidence interval 0.8–8.7, P = 0.12). Conclusions: Over‐oxygenation to hypercapnic COPD inpatients is common and rates of oxygen prescription are suboptimal. We found weak evidence of association between over‐oxygenation and adverse events, likely due to low statistical power. Larger prospective studies are needed. [ABSTRACT FROM AUTHOR]

Abstract: Global warming is causing the oceans to simultaneously warm, decrease in pH and increase in pCO2, stressors that will have deleterious impacts on physiological function in marine biota. To address questions on future vulnerabilities in a conspicuous component of the shallow water biota of temperate eastern Australia, the impact of projected (2100 and beyond) temperature and pH/pCO2 change on respiration in the brittle star Ophionereis schayeri was investigated. Survivorship at elevated temperature was also investigated. Temperature and pH conditions experienced by this species in the field were determined to place experiments in the context of present and near future scenarios and to assess current tolerance levels with regard to tidal variation in temperature and pH. The acute metabolic response (MO2) of O. schayeri to pH/pCO2 was measured with animals acclimated to 19°C, low summer sea surface temperature (SST) and 25°C (+1°C max summer SST). Temperature had the predicted effect on oxygen uptake, with the Q10 being 2.6 at normal pH 8.2. It was predicted that hypercapnia/low pH (7.4–7.8) would be stressful to O. schayeri and that this would be reflected by a decrease in respiration rate. Hypercapnia (pCO2 ≥ 1000μatm) had a narcotic effect causing lethargy in O. schayeri. In the pH 7.8 treatments narcotic effects may have contributed to the decrease in oxygen uptake observed. This pH level is near the lower range of pH experienced by this species in the field and it is likely that short term metabolic depression may be a routine response strategy for O. schayeri. However, at pH 7.6 and 7.4 O. schayeri exhibited a significant increase in oxygen uptake associated with copious secretion of mucus, a stress response. During five week acclimation experiments at control (22°C) and elevated (25°C) temperatures, mortalities were 1.3% and 15%, respectively. The brittle stars did not cope with higher temperatures (≥26°C). It appears that 25°C approximates the thermotolerance threshold for O. schayeri indicating that this species is living near its upper limit. Local populations of this brittle star may not cope with a more permanent increase in environmental pCO2 and temperature due to climate change. [Copyright &y& Elsevier]