Factors Associated with Pre-Event Hydration Status and Drinking Behavior of Middle-Aged Cyclists.

OBJECTIVES: Water is an essential nutrient for thermoregulation, metabolism, cognition, and overall physiological homeostatic function. However, aging adults display a blunted thirst mechanism and subsequently have an increased risk for dehydration or hyponatremia. Fluid consumption behaviors are modifiable and the importance of practicing adequate drinking behaviors for aging adults is amplified during exercise. Identification of aging adult's hydration beliefs and how they attain hydration advice could provide valuable information into ways to promote better drinking habits to reduce fluid imbalances. Thus, this investigation evaluated the knowledge, beliefs and behaviors of middle-aged cyclists (MA) that were associated with hydration status and drinking behavior, before and during a 164-km mass-participation event (ambient temperature, 33.3±2.8ºC(mean±SD)). DESIGN: This cross-sectional field study retrospectively grouped participants by their second urine specific gravity (Usg) measurement of the event morning prior to a mass participation cycling event. Usg was assessed via handheld refractometer. SETTING: The Hotter N' Hell Hundred 164-km cycling event in Wichita Falls, Texas during the month of August. PARTICIPANTS: 36 male recreational cyclists (age, 53±9 y(mean±SD)). MEASUREMENTS: Participants were grouped according their urine specific gravity as either slightly hyperhydrated (SH; n=12, Usg≤1.014), euhydrated (EUH; n=12, Usg, 1.015-1.020), or slightly dehydrated (SD; n=12, Usg≥1.021). Exercise histories and questionnaires were recorded 24-48 h prior to the cycling event. RESULTS: Regardless of pre-event hydration status, all groups experienced a similar body mass loss during the 164-km event and finished with statistically similar exercise times; also, drinking behavior within all groups was influenced by multiple factors. The primary factors associated with MA cyclist drinking behavior were trial and error/personal history and thirst; further, the majority of cyclists (≥65%) in SH, EUH, and SD believed that dehydration affects performance negatively. The least important factors included rehydration recommendations from scientific and sports medicine organizations, plus information from sports drink manufacturers. CONCLUSION: Considering the complexity of the present findings and the physiological changes that accompany aging such as delayed thirst perception, we recommend that MA cyclists formulate an individualized drinking plan that is based on observations during exercise.

Progesterone regulation of uterine dendritic cell function in rodents is dependent on the stage of estrous cycle.

Steroid hormones, such as progesterone, are able to modify immunity and influence disease outcome. Dendritic cells (DCs) drive potent immune responses, express receptors for steroid hormones, and may be a primary target of steroid hormone actions during infection of the genital tract, including uterine tissue. Here, we report that progesterone limited DC-associated activation marker expression and inhibited cytokine secretion by uterine DCs, which was associated with changes in signal transducer and activator of transcription 1 (STAT1) activity. We also found that DCs from mice at stages with higher progesterone concentrations (diestrus, metaestrus) were more sensitive to progesterone than those in stages with lower progesterone concentrations (proestrus, estrus), both in vitro and in vivo. This difference correlated with the levels of progesterone receptor expressed by DCs. These data suggest that progesterone regulates DC function and could contribute to the susceptibility of females to uterine and other genital tract infections at selected time periods throughout the life cycle.

Effects of dexamethasone on rat dendritic cell function.

Glucocorticoids have been reported to affect immunity at varying concentrations. While glucocorticoids have shown profound effects on innate immunity, their effects on rat dendritic cells have not been fully examined. In this study, we evaluated the effects of the synthetic glucocorticoid dexamethasone on cultured rat dendritic cells (DCs) from spleen and derived from bone marrow cells to determine whether responsiveness to dexamethasone varies between DCs from different organ sites. Cells were analyzed for expression of glucocorticoid receptor (GR), the primary receptor through which dexamethasone exerts its effects and was found to be primarily located in the cytoplasm of immature DCs. Bone marrow-derived DCs showed more sensitivity to dexamethasone treatment compared to splenic DCs. Dexamethasone treatment of LPS-matured DCs had profound dose-dependent effects on cytokine production. Dexamethasone treatment also led to a dose-dependent downregulation of expression of costimulatory molecules by mature DCs. Dexamethasone modified immature DC uptake of antigen (FITC-Dextran), with slightly higher numbers of splenic DCs taking up antigen compared to bone marrow-derived DCs. These data suggest that dexamethasone is able to similarly affect both bone marrow-derived and splenic DC function at the immature and mature DC states and could contribute to exacerbation of infection by hindering DC-mediated immune responses.

Quantification of Ara h 1 in peanuts: why roasting makes a difference.

BACKGROUND: Increased allergenicity of roasted vs. raw peanut has been reported by showing higher IgE binding to roasted peanut extracts. OBJECTIVE: To study the effect of roasting on Ara h 1 quantification in peanut using a specific monoclonal antibody-based ELISA, and to compare the Ara h 1 content from different kernel size peanuts from four runner cultivars. METHODS: Raw or oven-roasted (177 degrees C for 5-30 min) runner peanuts were crushed and extracted at 60 degrees C. Inhibition ELISA was used to study binding of Ara h 1 purified from raw or roasted peanut. Runner peanuts of four different cultivars were collected, shelled, sized and roasted for 15 min at 177 degrees C. Ara h 1 in the extracts was compared by ELISA. RESULTS: Ara h 1 levels were up to 22-fold higher in roasted than in raw peanuts (820 vs. 37 microg/mL, in a representative experiment) with an Ara h 1 peak at 10-15 min of roasting. Inhibition ELISA indicated that this increase was not due to conformational changes in the Ara h 1 monoclonal antibody epitopes. Ara h 1 was found at lower levels in number 1 than in jumbo- and medium-sized peanuts, and no differences were found among cultivars. CONCLUSION: These results suggest that roasting increases the efficiency of Ara h 1 extraction, and/or that the monoclonal antibody binding epitopes were more accessible in roasted peanut. Expression of Ara h 1 is associated with peanut maturity.