Microgravity Simulated by the 6° Head-Down Tilt Bed Rest Test Increases Intestinal Motility but Fails to Induce Gastrointestinal Symptoms of Space Motion Sickness.

BACKGROUND: Space motion sickness (SMS) is the most relevant medical problem during the first days in microgravity. Studies addressing pathophysiology in space face severe technical challenges and microgravity is frequently simulated using the 6° head-down tilt bed rest test (HDT). AIM: We were aiming to test whether SMS could be simulated by HDT, identify related changes in gastrointestinal physiology and test for beneficial effects of exercise interventions. METHODS: HDT was performed in ten healthy individuals. Each individual was tested in three study campaigns varying by a 30-min daily exercise intervention of either standing, an upright exercise regimen, or no intervention. Gastrointestinal symptoms, stool characteristics, gastric emptying time, and small intestinal transit were assessed using standardized questionnaires, (13)C octanoate breath test, and H2 lactulose breath test, respectively, before and at day 2 and 5 of HDT. RESULTS: Individuals described no or minimal gastrointestinal symptoms during HDT. Gastric emptying remained unchanged relative to baseline data collection (BDC). At day 2 of HDT the H2 peak of the lactulose test appeared earlier (mean ± standard error for BDC-1, HDT2, HDT5: 198 ± 7, 139 ± 18, 183 ± 10 min; p: 0.040), indicating accelerated small intestinal transit. Furthermore, during HDT, stool was softer and stool mass increased (BDC: 47 ± 6, HDT: 91 ± 12, recovery: 53 ± 8 g/day; p: 0.014), indicating accelerated colonic transit. Exercise interventions had no effect. CONCLUSION: HDT did not induce symptoms of SMS. During HDT, gastric emptying remained unchanged, but small and large intestinal transit was accelerated.

Trace Level Analysis of Per- and Polyfluorinated Substances in Fish from Various Regions in Switzerland.

Per- and polyfluorinated substances (PFASs) are persistent man-made chemicals which can end up in the food chain. In this study, the concentrations of 15 PFASs in various wild fish species from different regions in Switzerland were determined excluding hot spots of contamination. After clean-up with SPE, the samples were analyzed by HPLC-MS/MS. PFASs were detected in all but 1 of the 83 fish samples (0.07 to 40.7 µg/kg fish muscle meat). The most abundant compound in fish from subalpine lakes was perfluorooctane sulfonic acid (PFOS), comprising more than 80% of the total contamination while perfluorononanoic (PFNA), -decanoic (PFDA) and -undecanoic (PFUnDA) acid dominated in high alpine fish. PFAS levels were more elevated in subalpine lakes (median PFASs 11.1-19.0 µg/kg) than in the high alpine Lake Sils (median PFASs 0.66-2.67 µg/kg) or streams and canals in Valais (median PFASs 0.56 µg/kg). Our results indicate that wild fish may be one of the PFAS sources in human diet.

Antioxidant responses to an acute ultra-endurance exercise: impact on DNA stability and indications for an increased need for nutritive antioxidants in the early recovery phase.

Antioxidant requirements have neither been defined for endurance nor been defined for ultra-endurance athletes. To verify whether an acute bout of ultra-endurance exercise modifies the need for nutritive antioxidants, we aimed (1) to investigate the changes of endogenous and exogenous antioxidants in response to an Ironman triathlon; (2) to particularise the relevance of antioxidant responses to the indices of oxidatively damaged blood lipids, blood cell compounds and lymphocyte DNA and (3) to examine whether potential time-points of increased susceptibility to oxidative damage are associated with alterations in the antioxidant status. Blood that was collected from forty-two well-trained male athletes 2 d pre-race, immediately post-race, and 1, 5 and 19 d later was sampled. The key findings of the present study are as follows: (1) Immediately post-race, vitamin C, α-tocopherol, and levels of the Trolox equivalent antioxidant capacity, the ferric reducing ability of plasma and the oxygen radical absorbance capacity (ORAC) assays increased significantly. Exercise-induced changes in the plasma antioxidant capacity were associated with changes in uric acid, bilirubin and vitamin C. (2) Significant inverse correlations between ORAC levels and indices of oxidatively damaged DNA immediately and 1 d post-race suggest a protective role of the acute antioxidant responses in DNA stability. (3) Significant decreases in carotenoids and γ-tocopherol 1 d post-race indicate that the antioxidant intake during the first 24 h of recovery following an acute ultra-endurance exercise requires specific attention. Furthermore, the present study illustrates the importance of a diversified and well-balanced diet to maintain a physiological antioxidant status in ultra-endurance athletes in reference to recommendations.

DNA damage in response to an Ironman triathlon.

The major aims of this study were to investigate the effect of an Ironman triathlon on DNA migration in the single cell gel electrophoresis assay, apoptosis and necrosis in the cytokinesis-block micronucleus cytome assay with lymphocytes and on changes of total antioxidant capacity in plasma. Blood samples were taken 2 days (d) before, within 20 min, 1 d, 5 d and 19 d post-race. The level of strand breaks decreased (p<0.05) immediately after the race, then increased (p<0.01) 1 d post-race and declined (p<0.01) until 19 d post-race. Apoptotic and necrotic cells decreased (p<0.01) and the total antioxidant status increased (p<0.01) immediately after the race. The results indicate that ultra-endurance exercise does not cause prolonged DNA damage in well-trained male athletes.