Exercise-Associated Hyponatremia: The Effects of Carbohydrate and Hydration Status on IL-6, ADH, and Sodium Concentrations

Exercise-associated hyponatremia (serum sodium \u3c 135 mmol/L) is a rare, but serious condition that has been identified in those engaging in prolonged, physical activity conducted in the heat. PURPOSE: The purpose of this study was to evaluate the effect of hydration status and glycogen level on plasma IL-6, ADH, and sodium concentrations during and after prolonged exercise in the heat. METHODS: Ten male participants completed four trials: a glycogen depleted, euhydrated condition (DE); a glycogen depleted, dehydrated condition (DD); a glycogen loaded, euhydrated condition (LE); and a glycogen loaded, dehydrated condition (LD) consisting of cycling 90 minutes at 60% VO2 max in a 35˚C environment followed by a 3-h rehydration (RH) period. During RH, subjects received either 150% of fluid lost (DD & LD) or an additional 50% of fluid lost (DE & LE). Exercise and RH blood samples were analyzed for glucose, IL-6, ADH, and Na+. Sweat and urine samples were analyzed for [Na+]. RESULTS: Post-exercise to post-rehydration [Na+] changes for LD, DD, DE and LE were -6.85, -6.7, -1.45 and 0.10 mM, respectively. Post-exercise [IL-6] for DD, LD, DE, and LE were 5.4, 4.0, 3.7, and 3.49 pg/mL, respectively. Post-exercise [ADH] for LD, DD, DE, and LE were 21.5, 12.8, 7.6, and 1.9 pg/mL, respectively. The number of hyponatremic measurements for all RH samples was 5, 5, 20, and 10 for LD, DD, DE, and LE, respectively. CONCLUSION: Despite our glycogen and hydration manipulations, no regulatory effects of IL-6 and ADH on plasma sodium were observed. The timing of fluid intake did alter plasma sodium since euhydration during exercise combined with an additional 50% intake during RH, and a post-exercise RH volume of 150% of fluid lost both resulted in sodium concentrations below initial levels. Supported by a grant from the Gatorade Sports Science Institute

Historical resources, uncertainty and preservation values: An application of option and optimal stopping models

Historical Preservation, Uncertainty, Nonuse Values,

Common Strategies and Technologies for the Ecosafety Assessment and Design of Nanomaterials Entering the Marine Environment

The widespread use of engineered nanomaterials (ENMs) in a variety of technologies and consumer products inevitably causes their release into aquatic environments and final deposition into the oceans. In addition, a growing number of ENM products are being developed specifically for marine applications, such as antifouling coatings and environmental remediation systems, thus increasing the need to address any potential risks for marine organisms and ecosystems. To safeguard the marine environment, major scientific gaps related to assessing and designing ecosafe ENMs need to be filled. In this Nano Focus, we examine key issues related to the state-of-the-art models and analytical tools being developed to understand ecological risksand to design safeguards for marine organisms

Environmental behaviour and ecotoxicity of engineered nanoparticles to algae, plants and fungi

15 páginas, 4 figuras, 1 tabla.-- From the issue entitled "Special issue on Ecotoxicology, Chemistry and Risk Assessment of Nanoparticles. Guest Editors: Richard Handy and Richard Owen".-- et al.Developments in nanotechnology are leading to a rapid proliferation of new materials that are likely to become a source of engineered nanoparticles (ENPs) to the environment, where their possible ecotoxicological impacts remain unknown. The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi. Interactions of ENPs with natural organic matter have to be considered as well, as those will alter the ENPs aggregation behavior in surface waters or in soils. Cells of plants, algae, and fungi possess cell walls that constitute a primary site for interaction and a barrier for the entrance of ENPs. Mechanisms allowing ENPs to pass through cell walls and membranes are as yet poorly understood. Inside cells, ENPs might directly provoke alterations of membranes and other cell structures and molecules, as well as protective mechanisms. Indirect effects of ENPs depend on their chemical and physical properties and may include physical restraints (clogging effects), solubilization of toxic ENP compounds, or production of reactive oxygen species. Many questions regarding the bioavailability of ENPs, their uptake by algae, plants, and fungi and the toxicity mechanisms remain to be elucidated.Peer reviewe