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International recommendations advise against the use of intravenous rehydration therapy in children with severe acute malnutrition because of the concern about fluid overload, but evidence to support this concern is lacking. Given the high mortality associated with the current recommendations, the adoption of intravenous rehydration strategies might improve outcomes. We conducted a factorial, open-label superiority trial in four countries in Africa. Children 6 months to 12 years of age with severe acute malnutrition with gastroenteritis and dehydration underwent randomization in a 2:1:1 ratio to one of three rehydration strategies: oral rehydration, plus intravenous boluses for shock; a rapid intravenous strategy that consisted of lactated Ringer's solution (100 ml per kilogram of body weight) administered over a period of 3 to 6 hours, with boluses for shock; or a slow intravenous strategy that consisted of the same solution administered over a period of 8 hours, with no boluses. The primary end point was death at 96 hours. A total of 272 children underwent randomization; 138 were assigned to the oral strategy, 67 to the rapid intravenous strategy, and 67 to the slow intravenous strategy. Participants were followed for 28 days. A nasogastric tube was used for oral rehydration in 126 of 135 participants (93%) in the oral group and in 82 of 126 (65%) in the intravenous groups. Intravenous boluses were administered at admission in 12 participants (9%) in the oral group, 7 (10%) in the rapid intravenous group, and none in the slow intravenous group. At 96 hours, 11 participants (8%) in the oral group and 9 (7%) in the intravenous groups (5 in the rapid group and 4 in the slow group) had died (risk ratio, 1.02; 95% confidence interval [CI], 0.41 to 2.52; P = 0.69). At 28 days, 17 participants (12%) in the oral group and 14 (10%) in the intravenous groups had died (hazard ratio, 0.85; 95% CI, 0.41 to 1.78). Serious adverse events occurred in 32 participants (23%) in the oral group, 14 (21%) in the rapid intravenous group, and 10 (15%) in the slow intravenous group. No evidence of pulmonary edema, heart failure, or fluid overload was noted. Among children with severe acute malnutrition and gastroenteritis, no evidence of a difference in mortality at 96 hours was noted between oral and intravenous rehydration strategies. (Funded by the Joint Global Health Trials scheme and others; GASTROSAM Current Controlled Trials number, ISRCTN76149273.).

The present study evaluated, using a well-controlled dehydration protocol, the effects of 24 h fluid deprivation (FD) on selected mood and physiological parameters. In the present cross-over study, twenty healthy women (age 25 ( se 0·78) years) participated in two randomised sessions: FD-induced dehydration v . a fully hydrated control condition. In the FD period, the last water intake was between 18.00 and 19.00 hours and no beverages were allowed until 18.00 hours on the next day (23–24 h). Water intake was only permitted at fixed periods during the control condition. Physiological parameters in the urine, blood and saliva (osmolality) as well as mood and sensations (headache and thirst) were compared across the experimental conditions. Safety was monitored throughout the study. The FD protocol was effective as indicated by a significant reduction in urine output. No clinical abnormalities of biological parameters or vital signs were observed, although heart rate was increased by FD. Increased urine specific gravity, darker urine colour and increased thirst were early markers of dehydration. Interestingly, dehydration also induced a significant increase in saliva osmolality at the end of the 24 h FD period but plasma osmolality remained unchanged. The significant effects of FD on mood included decreased alertness and increased sleepiness, fatigue and confusion. The most consistent effects of mild dehydration on mood are on sleep/wake parameters. Urine specific gravity appears to be the best physiological measure of hydration status in subjects with a normal level of activity; saliva osmolality is another reliable and non-invasive method for assessing hydration status.

Purpose The effects of low-intensity exercise, heat-induced hypo-hydration and rehydration on maximal strength and the underlying neurophysiological mechanisms are not well understood. Methods To assess this, 12 participants took part in a randomised crossover study, in a prolonged (3 h) submaximal (60 W) cycling protocol under 3 conditions: (i) in 45 °C (achieving ~ 5% body mass reduction), with post-exercise rehydration in 2 h (RHY2), (ii) with rehydration across 24 h (RHY24), and (iii) a euhydrated trial in 25 °C (CON). Dependent variables included maximal voluntary contractions (MVC), maximum motor unit potential (M MAX ), motor evoked potential (MEP RAW ) amplitude and cortical silent period (cSP) duration. Blood–brain-barrier integrity was also assessed by serum Ubiquitin Carboxyl-terminal Hydrolase (UCH-L1) concentrations. All measures were obtained immediately pre, post, post 2 h and 24 h. Results During both dehydration trials, MVC (RHY2: p  < 0.001, RHY24: p  = 0.001) and MEP RAW (RHY2: p  = 0.025, RHY24: p  = 0.045) decreased from pre- to post-exercise. MEP RAW returned to baseline during RHY2 and CON, but not RHY24 ( p  = 0.020). MEP/M MAX ratio decreased across time for all trials ( p  = 0.009) and returned to baseline, except RHY24 ( p  < 0.026). Increased cSP ( p  = 0.011) was observed during CON post-exercise, but not during RHY2 and RHY24. Serum UCH-L1 increased across time for all conditions ( p  < 0.001) but was not significantly different between conditions. Conclusion Our findings demonstrate an increase in corticospinal inhibition after exercise with fluid ingestion, but a decrease in corticospinal excitability after heat-induced hypo-hydration. In addition, low-intensity exercise increases peripheral markers of blood–brain-barrier permeability. Graphical abstract The mechanisms and time-course of change in neuromuscular function after intracellular dehydration and subsequent rehydration, are not well understood. In this present study, twelve healthy participants underwent a control trial (CON) and two experimental trials in heat (45 °C, 45% relative humidity [RH]) to achieve a 5% reduction in body mass via dehydration and low-intensity cycling (60 W), then rehydrated rapidly (RHY2) or progressively (RHY24). Participants underwent various measures of transcranial magnetic stimulation (TMS) and peripheral motor nerve stimulation (MNS) before (PRE), after core temperature (CT) returned to baseline (POST), and after 2 h and 24 h. These measures included: motor evoked potential amplitude (MEP), TMS-evoked cortical silent period (cSP), compound muscle action potential (M MAX ), voluntary activation (VA), potentiated twitch (Qtw,pot), maximal voluntary contractions (MVC) and serum Ubiquitin carboxyl-terminal hydrolase (UCH-L1). The novel finding was a different corticospinal response to low-intensity exercise (i.e., higher corticospinal inhibition when hydrated) and rehydration strategies (i.e., lower corticospinal excitability after gradual rehydration).

Objectives To compare efficacy and safety of intramuscular (IM) ondansetron with oral ondansetron for improving utilization of Oral Rehydration Therapy (ORT) by controlling vomiting in children with acute diarrhea and some dehydration. Methods We enrolled children aged 3 months to 12 years presenting with acute diarrhea (duration < 14 days) with some dehydration, and at least two episodes of vomiting within last 6 h in an open-label randomized controlled trial. Participants were randomized to receive single dose (0.2 mg/kg) of IM or oral ondansetron before starting ORT. Primary outcome was failure of ORT (persistence of some dehydration after 4 h of ORT or need for intravenous fluids). Secondary outcomes included need for unscheduled intravenous fluids, amount of Oral Rehydration Salt Solution (ORS) ingested after 4 h, frequency of vomiting episodes, adverse effects, and caregiver satisfaction. Results We randomized 60 children (31 IM, 29 oral); 58 (29 per group) were followed-up for all outcomes. There were no significant differences between IM and oral routes in terms of ORT failure (31% vs. 24.1%; RR (95% CI) 1.3 (0.5, 3.0), P  = 0.557), need for IV fluids during ORT (24.1% vs. 20.7%; P  = 0.753), mean (SD) ORS ingested (mL) in 4 h [616.2 (429.7) vs. 645.5 (403.5); P  = 0.79], mean (SD) frequency of vomiting [1.4 (2.0) vs. 2.3 (2.4); P  = 0.107] or caregiver satisfaction. No adverse events attributable to the intervention were observed. Conclusion Intramuscular ondansetron may not offer any advantage over oral use in management of children with acute diarrhea with vomiting and some dehydration. Trial registration Clinical Trials Registry-India (CTRI/2020/01/023082) available at ctri.nic.in.

Systemic hydration is known to promote optimal functioning of bodily systems—including the vocal folds. The impact of systemic dehydration on the biology of the vocal folds and the downstream effects of dehydration on voice output are not well understood. An in vivo rat model of systemic dehydration was employed to investigate vocal fold gene expression, histological changes, and acoustic changes in vocalization. Ultrasonic vocalizations (USVs) were recorded every day for 5 days (baseline), in male and female Long-Evans rats (N = 36, ages: 3–4 months) using an anticipatory reward paradigm. Next, rats were dehydrated (N = 18) using a published water-restriction model for 5 days or euhydrated (N = 18) and provided ad libitum access to water for 5 days. USVs were recorded daily during the dehydration/euhydration period. The USV variables were averaged at baseline and following dehydration/euhydration for individual animals, and the difference between these time periods was used for statistical analysis. USV analysis included total USV count, complexity ratio, duration (s), frequency range (kHz), and maximum intensity (dB). At the end of dehydration/euhydration, animals were euthanized, and kidney and vocal fold tissue samples were dissected and processed for histology and gene expression analysis. Compared to euhydrated rats, dehydrated male and female rats had significantly up-regulated gene expression of kidney renin (male p = 0.047; female p = 0.018), indicating physiologic dehydration. There were no statistically significant differences in the USV acoustic profile or histopathology between the two groups. Differential expression ( p < 0.05) of several genes related to extracellular matrix remodeling, inflammatory responses, and water ion transport in the vocal folds was present. Our results indicate that mild systemic dehydration impacts gene expression in the vocal fold mucosa; however, these gene expression changes are not evident in the acoustic profile of vocalizations.

In the Author Contributions section, Saiedeh Saghafi (SS) should be listed as one of the persons who performed the experiments. Citation: Becker K, Jährling N, Saghafi S, Weiler R, Dodt H-U (2012) Correction: Chemical Clearing and Dehydration of GFP Expressing Mouse Brains.

Evaluating and testing hydration status is increasingly requested by rehabilitation, sport, military and performance-related activities. Besides commonly used biochemical hydration assessment markers within blood and urine, which have their advantages and limitations in collection and evaluating hydration status, there are other potential markers present within saliva, sweat or tear. This literature review focuses on body fluids saliva, sweat and tear compared to blood and urine regarding practicality and hydration status influenced by fluid restriction and/or physical activity. The selected articles included healthy subjects, biochemical hydration assessment markers and a well-described (de)hydration procedure. The included studies (n=16) revealed that the setting and the method of collecting respectively accessing body fluids are particularly important aspects to choose the optimal hydration marker. To obtain a sample of saliva is one of the simplest ways to collect body fluids. During exercise and heat exposures, saliva composition might be an effective index but seems to be highly variable. The collection of sweat is a more extensive and time-consuming technique making it more difficult to evaluate dehydration and to make a statement about the hydration status at a particular time. The collection procedure of tear fluid is easy to access and causes very little discomfort to the subject. Tear osmolarity increases with dehydration in parallel to alterations in plasma osmolality and urine-specific gravity. But at the individual level, its sensitivity has to be further determined.

Background The impacts of multicomponent school water, sanitation, and hygiene (WaSH) interventions on children’s health are unclear. We conducted a cluster-randomized controlled trial to test the effects of a school WaSH intervention on children’s malnutrition, dehydration, health literacy (HL), and handwashing (HW) in Metro Manila, Philippines. Methods The trial lasted from June 2017 to March 2018 and included children, in grades 5, 6, 7, and 10, from 15 schools. At baseline 756 children were enrolled. Seventy-eight children in two clusters were purposively assigned to the control group (CG); 13 clusters were randomly assigned to one of three intervention groups: low-intensity health education (LIHE; two schools, n = 116 children), medium-intensity health education (MIHE; seven schools, n = 356 children), and high-intensity health education (HIHE; four schools, n = 206 children). The intervention consisted of health education (HE), WaSH policy workshops, provision of hygiene supplies, and WaSH facilities repairs. Outcomes were: height-for-age and body mass index-for-age Z scores (HAZ, BAZ); stunting, undernutrition, overnutrition, dehydration prevalence; HL and HW scores. We used anthropometry to measure children’s physical growth, urine test strips to measure dehydration, questionnaires to measure HL, and observation to measure HW practice. The same measurements were used during baseline and endline. We used multilevel mixed-effects logistic and linear regression models to assess intervention effects. Results None of the interventions reduced undernutrition prevalence or improved HAZ, BAZ, or overall HL scores. Low-intensity HE reduced stunting (adjusted odds ratio [aOR] 0.95; 95% CI 0.93 to 0.96), while low- (aOR 0.57; 95% CI 0.34 to 0.96) and high-intensity HE (aOR 0.63; 95% CI 0.42 to 0.93) reduced overnutrition. Medium- (adjusted incidence rate ratio [aIRR] 0.02; 95% CI 0.01 to 0.04) and high-intensity HE (aIRR 0.01; 95% CI 0.00 to 0.16) reduced severe dehydration. Medium- (aOR 3.18; 95% CI 1.34 to 7.55) and high-intensity HE (aOR 3.89; 95% CI 3.74 to 4.05) increased observed HW after using the toilet/urinal. Conclusion Increasing the intensity of HE reduced prevalence of stunting, overnutrition, and severe dehydration and increased prevalence of observed HW. Data may be relevant for school WaSH interventions in the Global South. Interventions may have been more effective if adherence was higher, exposure to interventions longer, parents/caregivers were more involved, or household WaSH was addressed. Trial registration number DRKS00021623.

A simple, green, and highly efficient protocol for the synthesis of isocyanides is described. The reaction involves dehydration of formamides with phosphorus oxychloride in the presence of triethylamine as solvent at 0 °C. The product isocyanides were obtained in high to excellent yields in less than 5 min. The method offers several advantages including increased synthesis speed, relatively mild conditions, and rapid access to large numbers of functionalized isocyanides, excellent purity, increased safety, and minimal reaction waste. The new approach of synthesising dehydrative isocyanides from formamides is significantly more environmentally-friendly than prior methods.

ObjectiveTo compare hyperthermia and physiological dehydration risk during exercise heat stress between children of different ages and adults and evaluate an existing adult sweat rate calculator in children.Methods68 fit and recreationally active children aged 10–16 years (31 girls), and 24 adults aged 18–40 years (11 females) completed three separate 45 min treadmill walking/running trials at different intensities on different days at 30°C, 40% relative humidity (RH) (WARM) or 40°C, 30% RH (HOT). Exposures were randomised to elicit intensities scaled to (1) fitness, (2) mass and (3) surface area. Core (gastrointestinal (Tgi)) temperature was measured continuously and dehydration determined using body mass changes.ResultsExcept for 60% V̇O2peak in WARM, in which adults exhibited a greater Tgi rise compared with 10–13 years, there was no effect of age on Tgi during exercise (p≥0.176). Physiological rates of dehydration were not affected by age in WARM (p≥0.08) or HOT (p≥0.08). Mean predicted sweat rate error was +0.08 kg/hour (95% CIs: −0.10, +0.25) across WARM and HOT, and 80.5% of variability in sweating was explained by the adult sweat rate calculator.ConclusionsUsing the most comprehensive paediatric exercise heat stress dataset from a single study to date, we show that children aged 10–16 years are at a similar risk of hyperthermia and dehydration as adults during exercise up to 40°C. This supports recent changes to paediatric sport heat policies that were based on limited data. Practitioners can potentially reduce behavioural dehydration risks from inadequate fluid consumption using an existing adult sweat rate calculator for children.