Thirst Sensation Does Not Effect Reaction Time But Decreses Mood in Men

Exercise in hot environments results in dehydration accompanied by thirst sensation, a vital signal for fluid homeostasis. While cognitive performance and mood have been studied with exercise in hot environments and in dehydration states, no studies have investigated the effect of inducing thirst on cognitive performance and mood. PURPOSE: To investigate the effect of inducing thirst on cognitive performance and mood. METHODS: Twelve recreationally active men (mean±SE age: 29±3.6 years; body mass: 74.7±2.3 kg; height, 179.4±2.0 cm; maximal oxygen consumption [VO2max]: 49.8±1.9 ml·kg−1·min−1) performed 90 mins of cycling at 55% VO2max in a environmentally controlled chamber (ambient temperature, 34.9±0.2°C; relative humidity, 30.3±0.3%; wind speed, 3.4 miles ×h-1) followed by a 12 km cycling time trial. Two experimental conditions were performed with: subjects drank 25 mL of water every 5 minutes (NT) and infused 25 mL of isotonic saline every 5 minutes via intravenous intravenous tube (T). to maintain hydration across conditions. Thirst was measured every 5 minutes with the visual analog scales. Additionally, rectal temperature (Trec), skin temperature (Tsk) were recorded every 5 minutes. The Environmental Symptoms Questionnaire (ESQ), Profile of Mood States (POMS), a modified flanker task, and body mass were performed and recorded at the beginning (Pre) and the end (Post) of each trial. The flanker task assesses reaction time with congruent and incongruent conditions. Incongruent measures executive function while congruent trials measure simple reaction time. RESULTS: There was no significance between body mass loss and USG (p\u3e.05) demonstrating similar hydration states between thirst intervention. Trec and thirst were significantly higher in T compared to NT after 15 minutes and throughout the 90 minutes of exercise and 12 km time trial (p.05). Subjects also reported more fatigued after exercise (Pre: 2.0±0.6, Post: 13.8±1.2, p.05). CONCLUSION: After inducing thirst with exercise in hot environments, subjects were more fatigued and experienced trouble concentrating, however, reaction time was not affected . More research is necessary, but the results of this study suggest strategies to mitigate thirst are important to maintain mood during physical performance, however, does not affect cognitive performance

Differential Effects of Oral vs. Intravenous Fluid Administration on Bioelectrical Impedance During Dehydration Induced by Exercise and Heat

There is continued debate regarding optimal evaluation of hydration. Bioimpedance analysis has been utilized to evaluate hydration status, but there is limited information regarding the ability of this technology to detect physiological changes occurring during acute dehydration. PURPOSE: To evaluate whether bioimpedance spectroscopy (BIS) detects changes in bioelectrical resistance (R) in response to dehydration induced by exercising in the heat, assess whether these changes are related to body mass changes, and determine if the route of fluid administration during the dehydration protocol influences these observations. METHODS: Twelve males (mean ± SD; age: 28.6 ± 12.4 y; body mass: 74.7 ± 7.9 kg; height: 179.4 ± 7.0 cm; VO2max: 49.8 ± 6.6 mL/kg/min) completed two randomized experimental trials, each consisting of 90 minutes of continuous cycling exercise at 55% VO2maxfollowed by a 12 km time trial in the heat (ambient temperature: 34.9 ± 0.6 °C; relative humidity: 30.3 ± 0.9 %; wind speed: 3.4 mile×h-1). During each trial, fluid was administered either orally (DRINK) or intravenously (IV). During the DRINK trial, participants drank 25 mL of water every 5 minutes. During the IV trial, participants received 25 mL of isotonic saline solution through their IV catheter every 5 minutes. Nude body mass and BIS data were collected before and after trials to assess hydration status. Data were analyzed using Pearson’s correlations and paired t-tests with p-values corrected via false discovery rate. RESULTS: Body mass decreased, without differences between conditions (IV: -2.3 ± 0.5%; DRINK: -2.4 ± 0.9%; p=0.85). However, significant differences were observed for changes in predicted R at zero frequency (R0; IV: -3.6 ± 4.6%; DRINK: 1.3 ± 5.6%; p=0.02) and R at 50 kHz (R50; IV: -3.2 ± 4.1%; DRINK: -0.2 ± 4.1%; p=0.04), without differences in predicted R at infinite frequency (R∞; IV: -2.4 ± 6.1%; DRINK: -1.1 ± 3.7%; p=0.45). In the IV condition, significant correlations between body mass changes and R changes were observed for R0 (r=-0.80; p=0.002), R50 (r=-0.85; p\u3c0.001), and R∞ (r=-0.84; p\u3c0.001); however, no correlations were observed in the DRINK condition (r=-0.06 to 0.13; p≥0.69 for each). CONCLUSION: Differences between oral and intravenous fluid administration were seemingly detected by bioelectrical resistance at low-to-moderate, but not high, frequencies. With intravenous administration, negative correlations between changes in body mass and changes in R at all frequencies were observed, unlike with oral fluid administration. These findings suggest a potential sensitivity of bioimpedance technologies for monitoring intravenous fluid administration in the context of acute dehydration. However, additional investigation is needed to confirm their utility during distinct fluid loss scenarios and to confirm if these technologies are useful in the context of oral intake of fluids varying in composition

A 6 bp Z-DNA hairpin binds two Zα domains from the human RNA editing enzyme ADAR1

AbstractThe Zα domain of the human RNA editing enzyme double-stranded RNA deaminase I (ADAR1) binds to left-handed Z-DNA with high affinity. We found by analytical ultracentrifugation and CD spectroscopy that two Zα domains bind to one d(CG)3T4(CG)3 hairpin which contains a stem of six base pairs in the Z-DNA conformation. Both wild-type Zα and a C125S mutant show a mean dissociation constant of 30 nM as measured by surface plasmon resonance and analytical ultracentrifugation. Our data suggest that short (≥6 bp) segments of Z-DNA within a gene are able to recruit two ADAR1 enzymes to that particular site

Mild Dehydration Led to Increased Difficulty Falling Asleep

Sleep is fundamental process that benefits health and overall quality of life which can be affected by various aspects of daily living such as dehydration. A study has yet to investigate the impacts of euhydration and mild dehydration on sleep. PURPOSE: The purpose of this study was to examine effects of euhydration, mild-dehydration, and ad libitum drinking on sleep. METHODS: Eighteen male participants (mean±SD; age, 23±4y; height, 175.8±5.7cm; weight, 80.1±9.7kg) reported to the laboratory with different hydration status for 4 consecutive mornings(Day 1, baseline; Day 2, euhydrated; Day 3, mild-dehydrated; Day 4, ad libitum drinking). Hydration status was monitored by first morning urine specific gravity (USG) and plasma osmolality. Sleepwas measured using the Karolinska sleep diary (KSD). RESULTS: USG (baseline, 1.024±0.006; euhydrated, 1.018±0.007; mild-dehydrated, 1.030±0.003; ad libitum, 1.021±0.008, pCONCLUSION: When subjects were mildly dehydrated, sleep duration was longer while it was more difficult to fall asleep. More research is necessary, but the results of this study suggest it may be important to maintain euhydration to fall asleep easier

The Effect of Heat Acclimatization and Heat Acclimation on Endurance Trained Athlete Substrate Utilization

Heat acclimatization (HAz) and Heat Acclimation (HA) are important strategies to induce thermoregulatory adaptations to mitigate negative impact of heat stress. However, despite improving endurance performance, few studies explore their impact on substrate utilization. PURPOSE: To investigate the effect of HAz and HA on endurance athlete substrate utilization during submaximal exercise in the heat. METHODS: Fourteen endurance-trained male athletes (mean ± SD; age, 33 ± 9 years; body mass, 70.9 ± 10.1 kg; height, 177.7 ± 6.4 cm; VO2max, 59.3 ± 7.4 ml·kg−1·min−1; % body fat, 8.5% ± 3.9%) participated in this study. Participants performed 60 mins bouts of submaximal exercise (58.9 ± 2.2% vVO2max) in the heat (ambient temperature [Tamb], 35.5 ± 0.2°C; %relative humidity [%RH], 46.4% ± 1.3%; wet bulb globe temperature [WBGT], 29.3 ± 0.3°C; wind speed 4.0 ± 0.1 km·h−1). Prior to heat exposure (baseline), following HAz (post-HAz), and post-HA. During 60 min exercise, oxygen consumption (VO2) and respiratory exchange ratio (RER) were measured at the beginning (5-10 min), middle (30-35 min), and ending stages (55-60 min) of the protocol. Following the baseline, participants underwent self-directed summer training (HAz). Following post-HAz trials, participants underwent 5 days of HA sessions, which involved exercising to induce hyperthermia (38.50°C-39.75°C) for 60 minutes in the heat (Tamb, 39.1 ± 0.5°C; %RH, 51.8% ± 2.6%; WBGT, 33.4 ± 0.8°C) over an eight-day stretch. RESULTS: RER was significantly higher post-HAz (mean ± standard error; 0.85 ± 0.01) compared to baseline (0.81 ± 0.01, p2 difference between baseline (38.9 ± 1.2 ml·kg−1·min−1), post-HAz (37.5 ± 1.3 ml·kg−1·min−1, p= 0.062), or post-HA (38.5 ± 1.3 ml·kg−1·min−1, p=0.668). CONCLUSION: Self-directed HAz may impact athlete substrate utilization when performing submaximal exercise in a heated environment. Additionally, RER decreases as time of submaximal exercise in the heat increases. Other factors such as, athlete fitness level and exercise intensity, should also be considered when drawing conclusions regarding RER

Habitual Fluid Intake Does Not Affect Sleep Parameters in Young Women.

Sleep is essential for optimal physical performance, cognitive function, recovery, and overall health. Similarly, hydration status has been shown to influence physical and cognitive functions. Dehydration can lead to impaired cognition and possibly impaired sleep. However, the effect of habitual total water intake (TWI) on sleep and recovery measures have not been examined. PURPOSE: To examine the effect of TWI on sleep and recovery measures in young women. METHODS: Twenty-two young women (age: 22.8±4.6 yrs; body mass: 60.0±9.5 kg; height: 164.6±6.1 cm) collected fluid intake and food consumption information across a 5 day period, and average TWI was calculated based on them. Then, participants were categorized in either High Drinker (HD; ³ 2.5L/day; n=13; age: 23.0±3.6 yrs) or Low Drinker (LD; £ 1.6 L/day; n=9; age: 23±3yrs). Sleep and recovery measures were collected using a wearable sleep-tracking device that participants wore for 5 consecutive days. Sleep and recovery measures were compared between HD and LD, using a two-tailed independent t-test and effect sizes (ES). ES were identified as either small (0.2-0.49), medium (0.5-0.79), and large (\u3e0.8). RESULTS: No significant differences were found in resting heart rate (HD: 63.7±4.6 bpm, LD: 61.9± 5.2 bpm; p=0.40), heart rate variability (HD: 58.2±14.1 ms, 69.6±40.9 ms; p=0.44), slow wave sleep (SWS) (HD: 1.5±0.4 hrs, LD: 1.4±0.3 hrs; p=0.55), SWS percentage (HD: 19.3±3.8 %, LD: 18.7±3.7 %; p=0.17) sleep consistency (HD: 65.2±15.6 %, LD: 63.3±7. 3%; p=0.71), and sleep efficiency (HD: 90.5±3.1 %, LD: 90.4±2.0 %; p=0.91). While there were no statistical differences, rapid eye movement (REM) sleep (HD: 2.0±0.4 hrs, LD: 1.6±0.7 hrs; p=0.17) and REM percentage (HD: 26.1±3.8 %, LD: 21.5±7.8 %; p=0.13) displayed the largest differences, with REM indicating a medium ES (d=0.70) and REM percentage having a large ES (d=0.80). CONCLUSION: Habitual fluid intake might not impact sleep measurement. However, based on ES, REM sleep and REM percentage potentially display a trend. Still, more research is necessary to further determine any correlations

Impact of Habitual Water Intake on Muscle Quality and Total Body Water-A Pilot Study

Proper hydration is essential for critical health and performance functions, such as muscle function and body fluid balance. The effect of acute hydration status has been studied on health and muscle performance; however, the effect of habitual water intake on muscle quality and total body water between high and low consumption has not been examined. PURPOSE: To determine the impact of habitual water intake on muscle quality and total body water. METHODS: Eleven women (age: 27.6±7.9 years; mass: 60.3±10.8 kg) provided a five-day dietary food log to categorize them into HIGH or LOW daily total water intake (TWI). TWI values \u3e2.5-3.3 L/day (HIGH) or \u3c 0.7-1.6 L/day (LOW) were used to determine groups. Bioelectrical impedance analysis (BIA) and ultrasound images were obtained to assess overall muscle quality and total body fluid balance between the two groups. Analysis of ultrasound images using ImageJ determined length (cm), cross-sectional area (CSA), and muscle quality through echo intensity (EI) of the participant’s right and left rectus femoris (RF). An independent sample T-Test and effect sizes (ES) were used to assess differences between HIGH and LOW. RESULTS: Due to this study being a pilot study, there was no significant differences in right RF length between LOW (1.44±0.22 cm) and HIGH (1.22±0.24 cm, p=0.153) with a large effect size of (ES=0.98). There were no significant differences in left RF length (p=0.861) between HIGH (1.46±0.28 cm) and LOW (1.42±0.32) groups with a trivial effect size (ES=0.11). Right RF CSA had non-significant differences between LOW (3.72±1.18 cm2) and HIGH (2.95±1.05 cm2, p=0.309) with medium effect (ES=0.68). There were no differences in CSA-left between HIGH (3.63 ± 1.06 cm) and LOW (3.83±1.44, p=0.816, ES=0.15). Right RF muscle quality also had a medium effect size (ES=0.78) between HIGH (135.30±21.82 A.U) and LOW (117.71±23.10 A.U). Muscle quality of the left RF had a small effect size (ES=0.26) between LOW (118.29±22.18 A.U) and HIGH (125.97±39.47 A.U, p=0.684). While there was no statistical difference due to the power (p=0.163), total body water (TBW) percentage (%) was greater in HIGH (53.9±1.5%) compared to LOW (50.6±5.4%, ES= 0.75) with medium effects. HIGH and LOW demonstrated no statistical difference (p=0.579) with a small effect size (ES=0.36) between ECF% and ICF%, respectively (41.00±0.72%, 41.39±1.20%; 59.00±0.72%, 58.61±1.20%). CONCLUSION: Despite no significant differences, based on ES, HIGH habitual water intake increases TBW% than LOW. Further data must be collected to draw definitive conclusions; however, these results suggest skeletal muscle quality is high with LOW habitual water intake

Characterization of Physical and Cognitive Performance and Hydration in Older Adults

In younger adults, dehydration has been shown to impair physical and cognitive performance. Older adults are habitually hypohydrated alongside experiencing physical and cognitive performance deficits. Despite these deficits, the link between these factors remains unexplored. Purpose: To examine the effect of hydration status on physical and cognitive performance in older adults. Methods: Sixteen (5 men and 11 women) community-dwelling adults (74±7yr; 78.2±15.0kg; 161±11cm) completed measurements of hydration status (urine specific gravity [USG], urine color), bioelectrical impedance analysis (lean mass, fat mass, total body fluid, intracellular to extracellular fluid ratio [ICF: ECF]), blood pressure, physical performance (handgrip strength test, sit-to-stand test, and a timed-up-and-go test), and reaction time (Flanker task). Hierarchical cluster analysis was performed on the distance matrix of USG and urine color to group participants. One-way ANOVAs were performed to determine differences among groups. Results: Hierarchical cluster analysis assigned participants to 4 groups (group1, n=3; group2, n=4; group3, n=5; group4,n=4). Consistent with the cluster analysis, each group had significantly (p1: 1.0±0.0, group2: 2.3±0.3, group3: 4.2±0.4, group4, 6.0±0.0). In addition, the reaction time was significantly different among groups. For group1, compatible and incompatible tasks (compatible: 1116±71.7s, p=0.049; incompatible: 1205±13.4ms, p=0.042) had a longer response time compared to group2(compatible: 640±67.5ms; incompatible: 688±74.0ms), group3 (compatible: 725±67.4ms; incompatible: 796±174.2ms), and group4 (compatible: 731±139.8ms; incompatible: 782±122.7ms). No significant differences were observed for lean mass, fat mass, total body fluid, ICF:ECF, blood pressure, handgrip strength, sit-to-stand test, and time-up-and-go test. Conclusion: Despite grouping by USG and urine color, no relationship was observed between body composition and physical performance. Surprisingly, hydrated individuals performed poorly cognitively compared to less hydrated individuals. We suggest these differences may reflect varying individual cognitive functions, not hydration status, among free-living older adults

Integrated monitoring and evaluation and environmental risk factors for urogenital schistosomiasis and active trachoma in Burkina Faso before preventative chemotherapy using sentinel sites.

BACKGROUND: Over 1 billion of the world's poorest inhabitants are afflicted by neglected tropical diseases (NTDs). Integrated control programmes aimed at tackling these debilitating NTDs have been recently initiated, mainly using preventative chemotherapy. Monitoring and evaluation (M&E) of these integrated programs presents particular challenges over and above those required for single disease vertical programmes. We used baseline data from the National NTD Control Programme in Burkina Faso in order to assess the feasibility of an integrated survey design, as well as to elucidate the contribution of environmental variables to the risk of either Schistosoma haematobium, trachoma, or both among school-aged children. METHODS: S. haematobium infection was diagnosed by detecting eggs in urine. A trachoma case was defined by the presence of Trachomatous inflammation-Follicular (TF) and/or Trachomatous inflammation-Intense (TI) in either eye. Baseline data collected from 3,324 children aged 7-11 years in 21 sentinel sites across 11 regions of Burkina Faso were analyzed using simple and multivariable hierarchical binomial logistic regression models fitted by Markov Chain Monte Carlo estimation methods. Probabilities of the risk of belonging to each infection/disease category were estimated as a function of age, gender (individual level), and environmental variables (at sentinel site level, interpolated from national meteorological stations). RESULTS: Overall prevalence at the sentinel sites was 11.79% (95% CI: 10.70-12.89) for S. haematobium; 13.30% (12.14-14.45) for trachoma and 0.84% (0.53-1.15) for co-infections. The only significant predictor of S. haematobium infection was altitude. There were significant negative associations between the prevalence of active trachoma signs and minimum temperature, and air pressure. Conditional upon these predictors, these data are consistent with the two pathogens being independent. CONCLUSIONS: Urogenital schistosomiasis and trachoma constitute public health problems in Burkina Faso. Sentinel site (at school level) surveys for these two NTDs can be implemented simultaneously. However, to support MDA treatment decisions in Burkina Faso, the protocol used in this study would only be applicable to hypoendemic trachoma areas. More research is needed to confirm if these findings can be generalized to West Africa and beyond

Cardiac Biomarkers and Risk of Atrial Fibrillation in Chronic Kidney Disease: The CRIC Study.

Background We tested associations of cardiac biomarkers of myocardial stretch, injury, inflammation, and fibrosis with the risk of incident atrial fibrillation (AF) in a prospective study of chronic kidney disease patients. Methods and Results The study sample was 3053 participants with chronic kidney disease in the multicenter CRIC (Chronic Renal Insufficiency Cohort) study who were not identified as having AF at baseline. Cardiac biomarkers, measured at baseline, were NT-proBNP (N-terminal pro-B-type natriuretic peptide), high-sensitivity troponin T, galectin-3, growth differentiation factor-15, and soluble ST-2. Incident AF ("AF event") was defined as a hospitalization for AF. During a median follow-up of 8 years, 279 (9%) participants developed a new AF event. In adjusted models, higher baseline log-transformed NT-proBNP (N-terminal pro-B-type natriuretic peptide) was associated with incident AF (adjusted hazard ratio [HR] per SD higher concentration: 2.11; 95% CI, 1.75, 2.55), as was log-high-sensitivity troponin T (HR 1.42; 95% CI, 1.20, 1.68). These associations showed a dose-response relationship in categorical analyses. Although log-soluble ST-2 was associated with AF risk in continuous models (HR per SD higher concentration 1.35; 95% CI, 1.16, 1.58), this association was not consistent in categorical analyses. Log-galectin-3 (HR 1.05; 95% CI, 0.91, 1.22) and log-growth differentiation factor-15 (HR 1.16; 95% CI, 0.96, 1.40) were not significantly associated with incident AF. Conclusions We found strong associations between higher NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity troponin T concentrations, and the risk of incident AF in a large cohort of participants with chronic kidney disease. Increased atrial myocardial stretch and myocardial cell injury may be implicated in the high burden of AF in patients with chronic kidney disease