Sweat Characteristics and Fluid Balance Responses During Two Heat Training Camps in Elite Female Field Hockey Players.

We examined the sweat characteristics and fluid balance of elite female field hockey players during two heat training camps. Fourteen elite female field hockey players from the Australian national squad participated in two heat training camps held ∼6 months apart, following winter- (Camp 1) and summer-based training (Camp 2). Daily waking body mass (BM) and urine specific gravity (USG) were collected, along with several markers of sweat and fluid balance across two matches per camp. There was a 19% mean reduction in estimated whole-body sweat sodium concentration from Camp 1 (45.8 ± 6.5 mmol/L) to Camp 2 (37.0 ± 5.0 mmol/L; p < .001). Waking urine specific gravity ≥ 1.020 was observed in 31% of samples, with no significant differences in mean urine specific gravity or BM between camps (p > .05), but with substantial interindividual variation. Intramatch sweat rates were high (1.2-1.8 L/hr), with greater BM losses in Camp 1 (p = .030), resulting in fewer players losing ≥2% BM in Camp 2 (0%-8%), as compared with Camp 1 (36%-43%; p = .017). Our field data suggest that elite female field hockey players experience substantial sweat losses during competition in the heat regardless of the season. In agreement with previous findings, we observed substantial interindividual variation in sweat and hydration indices, supporting the use of individualized athlete hydration strategies.

Effect of Personalized Sodium Replacement on Fluid and Sodium Balance and Thermophysiological Strain During and After Ultraendurance Running in the Heat.

PURPOSE: To investigate the effect of personalized sweat sodium replacement on drinking behavior, sodium and water balance, and thermophysiological responses during and after ultraendurance running in hot conditions. METHODS: Nine participants (7 male, 2 female) completed two 5-hour treadmill runs (60% maximum oxygen uptake, 30°C ambient temperature), in a double-blind randomized crossover design, consuming sodium chloride (SODIUM) capsules to replace 100% of previously assessed losses or placebo (PLACEBO). Fluid was consumed ad libitum. RESULTS: No effect of SODIUM was observed for ad libitum fluid intake or net fluid balance (P > .05). Plasma sodium concentration increased in both trials, but to a greater extent in SODIUM at 2.5 hours (mean [SD]: 4 [4] mmol·L-1 vs 1 [5] mmol·L-1; P < .05) and postexercise (4 [3] mmol·L-1 vs 1 [5] mmol·L-1; P < .05). Plasma volume change was not different between trials (P > .05) but was strongly correlated with sodium balance in SODIUM (r = .880, P < .01). No effect of sodium replacement was observed for heart rate, rectal temperature, thermal comfort, perceived exertion, or physiological strain index. During the 24 hours postexercise, ad libitum fluid intake was greater following SODIUM (2541 [711] mL vs 1998 [727] mL; P = .04), as was urinary sodium excretion (NaCl: 66 [35] mmol, Pl: 21 [12] mmol; P < .01). CONCLUSIONS: Personalized sweat sodium replacement during ultraendurance running in hot conditions, with ad libitum fluid intake, exacerbated the rise in plasma sodium concentration compared to no sodium replacement but did not substantially influence overall body-water balance or thermophysiological strain. A large sodium deficit incurred during exercise leads to substantial renal sodium conservation postexercise.

Patterns of ingestion of rats during chronic oral administration of lithium chloride.

Chronic lithium administration to rodents is used to explore the potential neural mechanisms of mood stabilization, as well as to model the side effects of chronic lithium on multiple organ systems. Oral administration of lithium in the maintenance diet or drinking water is convenient, but lithium can acutely affect intake and it can mediate acquisition of conditioned taste aversions (CTA). We compared ad libitum food and fluid intake by male rats with LiCl or NaCl solutions as their sole source of fluid across 20 days, with a commonly used dosage of LiCl (24 mM: 1 g / L LiCl). To quantify the pattern of intake, rats were housed in cages equipped with lickometers to detect licks and infrared photobeams to detect food access with 6-s resolution. To determine if rats formed a CTA to LiCl, they were subsequently tested with access to NaCl. Rats showed an immediate avoidance of the LiCl solution, as seen on the first day of access by an increased latency to initiate drinking and a decreased size of drinking bouts. Rats showed a differential response to LiCl vs. NaCl after as few as 5 licks. Chronic consumption of LiCl solution led to significantly decreased food and fluid intake compared to baseline, with concomitant weight loss. The decreased intake was realized by marked changes in the pattern of drinking and feeding bouts: a decrease in per-lick volume and a decrease in licks per drinking bout, and an increase in feeding bout duration resulting in an overall decrease in eating rate. Conversely, chronic NaCl access led to an increase in drinking bout number and licks/bout. The avoidance of LiCl was likely a combination of toxic effects of ingested LiCl and rapid acquisition of a learned aversion to the taste of LiCl, as shown by an extinguishable generalized aversion to NaCl solution during subsequent NaCl test days. The marked effect of chronic oral LiCl on ingestion may impact the oral dosing of lithium as well as the rat's metabolic status.

Repeatability of Ad Libitum Water Intake during Repeated 1 h Walking/Jogging Exercise Sessions Conducted under Hot Ambient Conditions.

A drinking strategy aiming to replace a given percentage of the sweat losses incurred during exercise should result in reproducible fluid intake volume and, hence, fluid balance from one exercise session to the other performed under similar scenarios. Whether this may also be the case with ad libitum drinking during exercise is unclear. We characterized the repeatability of ad libitum water intake during repeated 1 h exercise sessions and examined its effect over time on fluid balance and selected physiological functions and perceptual sensations. Twelve (3 women) healthy individuals participated in this study. At weekly intervals, they completed four 2 × 30 min walking/jogging exercise bouts (55% V˙O2max, 40 °C, 20-30% relative humidity) interspersed by a 3 min recovery period. During exercise, participants consumed water (20 °C) ad libitum. There were no significant differences among the four exercise sessions for absolute water intake volume (~1000 mL·h-1), percent body mass loss (~0.4%), sweat rate (~1300 mL·h-1) and percent of sweat loss replaced by water intake (~80%). Heart rate, rectal temperature, and perceived thirst and heat stress did not differ significantly between the first and fourth exercise sessions. Perceived exertion was significantly lower during the fourth vs. the first exercise session, but the difference was trivial (<1 arbitrary unit). In conclusion, ad libitum water intake during four successive identical 1 h walking/jogging sessions conducted in the heat will result in similar water intake volumes and perturbations in fluid balance, heart rate, rectal temperature, and perceived thirst, heat stress and exertion.

Dopaminergic error signals retune to social feedback during courtship.

Hunger, thirst, loneliness and ambition determine the reward value of food, water, social interaction and performance outcome1. Dopamine neurons respond to rewards meeting these diverse needs2-8, but it remains unclear how behaviour and dopamine signals change as priorities change with new opportunities in the environment. One possibility is that dopamine signals for distinct drives are routed to distinct dopamine pathways9,10. Another possibility is that dopamine signals in a given pathway are dynamically tuned to rewards set by the current priority. Here we used electrophysiology and fibre photometry to test how dopamine signals associated with quenching thirst, singing a good song and courting a mate change as male zebra finches (Taeniopygia guttata) were provided with opportunities to retrieve water, evaluate song performance or court a female. When alone, water reward signals were observed in two mesostriatal pathways but singing-related performance error signals were routed to Area X, a striatal nucleus specialized for singing. When courting a female, water seeking was reduced and dopamine responses to both water and song performance outcomes diminished. Instead, dopamine signals in Area X were driven by female calls timed with the courtship song. Thus the dopamine system handled coexisting drives by routing vocal performance and social feedback signals to a striatal area for communication and by flexibly re-tuning to rewards set by the prioritized drive.

Water consumption patterns impact hydration markers in males working in accordance with the National Institute for Occupational Safety and Health recommendations.

The impact of water consumption bolus volume and frequency on hydration biomarkers during work in the heat is unknown. In a randomized, crossover fashion, eight males consumed either 500 mL of water every 40 min or 237 mL of water every 20 min during 2 hr of continuous walking at 6.4 kph, 1.0% grade in a 34 °C/30% relative humidity environment, followed by 2 hr of rest. Hydration biomarkers and variables were assessed pre-work, post-work, and after the 2 hr recovery. There were no differences in body mass between trials at any time point (all p > 0.05). Percent change in plasma volume during work was not different when 237 mL of water was repeatedly consumed (-1.6 ± 8.2%) compared to 500 mL of water (-1.3 ± 3.0%, p = 0.92). Plasma osmolality was maintained over time (p = 0.55) with no difference between treatments (p = 0.21). When consuming 500 mL of water repeatedly, urine osmolality was lower at recovery (205 ± 108 mOsmo/L) compared to pre-work (589 ± 95 mOsmo/L, p < 0.01), different from repeatedly consuming 237 mL of water which maintained urine osmolality from pre-work (548 ± 144 mOsmo/L) through recovery (364 ± 261 mOsmo/L, p = 0.14). Free water clearance at recovery was greater with repeated consumption of 500 mL of water (1.2 ± 1.0 mL/min) compared to 237 mL of water (0.4 ± 0.8 mL/min, p = 0.02). Urine volume was not different between treatments post-work (p = 0.62), but greater after 2 hr of recovery when repeatedly consuming 500 mL of water compared to 237 mL (p = 0.01), leading to greater hydration efficiency upon recovery with repeated consumption of 237 mL of water (68 ± 12%) compared to 500 mL (63 ± 14%, p = 0.01). Thirst and total gastrointestinal symptom scores were not different between treatments at any time point (all p > 0.05). Body temperatures and heart rate were not different between treatments at any time point (all p > 0.05). Drinking larger, less frequent water boluses or drinking smaller, more frequent water boluses are both reasonable strategies to promote adequate hydration and limit changes in body mass in males completing heavy-intensity work in the heat.

Changes in the skin characteristics associated with dehydration and rehydration.

The present study aimed to test the hypothesis that changes in the dermal tissue dielectric constant (TDC) and biomechanical properties of the skin would be correlated with the indicators related to dehydration. Ten healthy adult men were enrolled in three trials: no fluid intake (DEH), ad libitum fluid intake (AL-HYD), and programmed fluid intake (P-HYD) after exercise in a randomised crossover design. The participants performed a pedalling exercise at 60% heart rate reserve until 2% body mass loss. At 120 min after exercise, an incremental exercise test was carried out. Aerobic capacity, body composition, TDC, biomechanical properties of the skin (pliability, viscoelasticity, and total recovery), and indicators related to dehydration in the serum and urine were measured before and 120 min after exercise. Higher values of the pliability and viscoelasticity, and lower value of the total recovery on the hand were demonstrated in the P-HYD trial compared to the DEH trial (all P < 0.05). Changes in the TDC were significantly correlated with changes in body mass, total body water, serum osmolarity, and hematocrit (all P < 0.05). Changes in the biomechanical properties of the hand were significantly correlated with changes in body mass, hematocrit, and urine specific gravity (all P < 0.05). The present study showed that the changes in skin characteristics correlated with the body water and dehydration-associated indicators in the serum and urine, thus suggesting that skin characteristics may be useful in the assessment of dehydration.HighlightsThis study was the first to investigate the effect of dehydration and rehydration on the TDC and biomechanical properties of the skin upon instrumental measure, and not manual testing.This study confirmed the decline in aerobic capacity by dehydration and immediate recovery with sufficient rehydration.Changes in the TDC and the biomechanical properties of the skin correlated with the body water and dehydration-associated indicators in the serum and urine.Skin characteristics may be useful in the assessment of dehydration.

Children's water intake and hydration: a public health issue.

Optimal hydration is required for all physiologic functions and cognition. Children, especially younger ones, are particularly susceptible to dehydration, given their physiological specificities, in particular, their renal immaturity and relatively large skin surface in early life, but also their dependence on adults and their greater propensity to develop digestive diseases leading to fluid losses. Mild dehydration consequences are dominated by their impact on cognitive functions, whereas more severe dehydration may endanger the health outcome. Studies on this subject in children are scarce; in particular, the long-term consequence on renal function remains questionable. This review considers how children's water intake including fluid intake and water content of food, are worrying. The findings show that, worldwide, most children do not meet adequate water intake recommendations. The main problems likely to explain insufficient water intake are access to safe water, availability of drinking water at school, and healthy-hydration education, which are all points that need to be improved within health policy.

Variation in human water turnover associated with environmental and lifestyle factors.

Water is essential for survival, but one in three individuals worldwide (2.2 billion people) lacks access to safe drinking water. Water intake requirements largely reflect water turnover (WT), the water used by the body each day. We investigated the determinants of human WT in 5604 people from the ages of 8 days to 96 years from 23 countries using isotope-tracking (2H) methods. Age, body size, and composition were significantly associated with WT, as were physical activity, athletic status, pregnancy, socioeconomic status, and environmental characteristics (latitude, altitude, air temperature, and humidity). People who lived in countries with a low human development index (HDI) had higher WT than people in high-HDI countries. On the basis of this extensive dataset, we provide equations to predict human WT in relation to anthropometric, economic, and environmental factors.

Post-Exercise Voluntary Drinking Cessation Is Associated with the Normalization of Plasma Osmolality and Thirst Perception, but Not of Urine Indicators or Net Fluid Balance.

Post-exercise rehydration has been widely studied, with particular emphasis on retention of ingested fluid; comparatively little research has been conducted on why we drink more or less. To identify physiological values corresponding to voluntary drinking cessation (VDC), nine males exercised intermittently at 70−80% HRmax in the heat (WBGT = 28.1 ± 0.7 °C) to achieve a dehydration of approximately 4.0% body mass (BM). After exercise, participants were instructed to drink water as long and as much as they needed. Urine color (Ucolor), specific gravity (USG), osmolality (Uosm), plasma osmolality (Posm), fullness, BM, and thirst perception (TP) were measured pre- and post-exercise and at VDC. Each variable was compared for the three points in time with a one-way ANOVA. Participants reached dehydration of −3.6 ± 0.3% BM. Pre-exercise USG (1.022 ± 0.004) was lower than at VDC (1.029 ± 0.004, p = 0.022), Uosm did not change over time (p = 0.217), and Ucolor was lower pre-exercise (3.4 ± 0.7) vs. post-exercise (5.5 ± 1.23, p = 0.0008) and vs. VDC (6.3 ± 1.1, p < 0.0001). Posm showed a difference between pre-exercise (289.5 ± 2.3) and post-exercise (297.8 ± 3.9, p = 0.0006) and between post-exercise and VDC (287.3 ± 5.4, p < 0.0001). TP post-exercise (96.4 ± 4.34) was significantly higher than pre-exercise (36.2 ± 19.1) and VDC (25.0 ± 18.2, p < 0.0001). At VDC, participants had recovered 58.7 ± 12.1% of BM loss. At the point of voluntary drinking cessation, Posm and thirst perception had returned to their pre-exercise values, while rehydration relative to initial BM was still incomplete.

Sensory biology: Thirsty glia motivate water consumption.

Regulation of water intake is governed by numerous motivated behaviors that are critical for the survival of nearly all animals. A recent study identifies a critical role for glia-neuron communication in the detection of water shortage and the initiation of thirst-associated behaviors.

Eating and Drinking Ability Classification System ­ EDACS: equivalência cultural para o português brasileiro / Eating and Drinking Ability Classification System ­ EDACS: cross-cultural adaptation of the Brazilian Portuguese / Eating and Drinking Ability Classification System ­ EDACS: equivalencia cultural para el portugués brasileño

Objetivo: realizar a tradução e equivalência cultural e linguística para o Português Brasileiro do Eating and Drinking Ability Classification System (EDACS). Método: realizou-se a tradução do EDACS para a língua portuguesa por duas fonoaudiólogas bilíngues e especialistas em disfagia. As duas traduções foram comparadas entre as próprias fonoaudiólogas, sendo as incompatibilidades discutidas entre si e decisões tomadas por consenso. Após o instrumento traduzido, este foi enviado para uma terceira fonoaudióloga, brasileira, bilíngue, residente nos Estados Unidos, para que a retrotradução para o inglês fosse realizada. A versão inicial do instrumento e a retro tradução foram confrontadas entre si, sendo as discrepâncias analisadas, discutidas e definidas por consenso. Resultados: os processos de tradução e adaptação cultural requereram maior esforço na definição da nomenclatura das consistências utilizadas e não trouxeram modificações com relação à estrutura da escala original. Conclusão: realizou-se a equivalência cultural do Sistema de Classificação das Habilidades do Comer e Beber ­ EDACS-PT/BR para o português brasileiro.

Objective: to perform the translation and cultural equivalence to Brazilian Portuguese of the Eating and Drinking Ability Classification System (EDACS). Method: EDACS was translated into Brazilian Portuguese by two bilingual speech language therapists, specialists in dysphagia. The two translations were compared by the speech therapists, the incompatibilities were discussed among themselves and decisions were taken by consensus. After the instrument was translated, it was sent to a third Brazilian speech language therapist, bilingual and resident in the United States, for back-translation into English. The initial version of the instrument and the back-translation were compared and the discrepancies were analyzed, discussed and defined by consensus. Results: the processes of translation and cultural adaptation required more effort in defining the terms of the used consistencies and did not change the structure of the original scale. Conclusion: the cultural equivalence of the Sistema de Classificação das Habilidades do Comer e Beber ­ EDACS-PT/BR was performed for Brazilian Portuguese.

Objetivo: llevar a cabo la traducción y equivalencia cultural y lingüística al portugués brasileño del Eating and Drinking Ability Classification System (EDACS). Método: la EDACS fue traducida al portugués por dos logopedas bilingües y especialistas en disfagia. Las dos traducciones se compararon entre los propios logopedas, discutiéndose las incompatibilidades y tomando decisiones por consenso. Una vez traducido el instrumento, se envió a un tercer logopeda, brasileño, bilingüe, residente en Estados Unidos para la retrotraducción al inglés. La versión inicial del instrumento y la retrotraducción se compararon entre sí, y las discrepancias fueron analizadas, discutidas y definidas por consenso. Resultados: los procesos de traducción y adaptación cultural requirieron un mayor esfuerzo en la definición de la nomenclatura de las consistencias utilizadas y no trajeron cambios en relación a la estructura de la escala original. Conclusión: se realizó la equivalencia cultural del Sistema de Classificação das Habilidades do Comer e Beber ­ EDACS-PT/BR para el portugués brasileño.

Water intake, thirst, and copeptin responses to two dehydrating stimuli in lean men and men with obesity.

OBJECTIVE: Physiological systems responsible for water homeostasis and energy metabolism are interconnected. This study hypothesized altered responses to dehydration including thirst, ad libitum water intake, and copeptin in men with obesity. METHODS: Forty-two men (22 lean and 20 with obesity) were stimulated by a 2-hour hypertonic saline infusion and a 24-hour water deprivation. In each dehydrating condition, thirst, ad libitum water intake after dehydration, and urinary and hormonal responses including copeptin were assessed. RESULTS: After each dehydration condition, ad libitum water intake was similar between both groups (p > 0.05); however, those with obesity reported feeling less thirsty (p < 0.05) and had decreased copeptin response and higher urinary sodium concentrations when stressed (p < 0.05). Angiotensin II, aldosterone, atrial and brain natriuretic peptides, and apelin concentrations did not differ by adiposity group and did not explain the different thirst or copeptin responses in men with obesity. However, leptin was associated with copeptin response in lean individuals during the hypertonic saline infusion (p < 0.05), but the relationship was diminished in those with obesity. CONCLUSIONS: Diminished thirst and copeptin responses are part of the obesity phenotype and may be influenced by leptin. Adiposity may impact pathways regulating thirst and vasopressin release, warranting further investigation.

Water supplementation affects the fluid intake and serum levels of BDNF among the elderly nursing home residents.

OBJECTIVES: The link between dehydration and fluid intake with brain function in elderly individuals has produced conflicting findings. The aim of this study was to examine the effects of water supplementation on fluid intake, cognitive and motor performance, and serum brain-derived neurotrophic factor (BDNF) levels in euhydrated and dehydrated elderly. METHODS: Twenty participants 60 to 89 y of age were randomly divided into four groups, namely; euhydration + control (EC), euhydration + treatment (ET), dehydration + control (DC), and dehydration + treatment (DT) groups. The treatment groups were personally supplemented with plain water for 7 d. The volume of water intake was assessed with food recalls. The digit span test and finger tapping test were used to examine cognitive and motor performances. Peripheral BDNF levels were determined using enzyme-linked immunosorbent assay of serum samples. RESULTS: Water supplementation increased 2.5 times the volume of water and total fluid intake in the ET and DT groups. The mean of the volume water intake on day 7 in ET and DT was significantly different from EC (P < 0.01) and DC (P < 0.001) groups. Serum BDNF levels were higher on preintervention in dehydration compared to euhydration groups (P < 0.05) and significantly negative correlated with the volume of water (r = -0.59, P = 0.006) and fluid intake (r = -0.60, P = 0.004). CONCLUSIONS: The present study demonstrated that 7 d of water supplementation increased the water and the total fluid intake in elderly individuals regardless of dehydration status. Serum BDNF levels increased during dehydration and reverted to physiologic levels after appropriate rehydration.

Association of water intake and hydration status with risk of kidney stone formation based on NHANES 2009-2012 cycles.

OBJECTIVE: Evaluating the association of water intake and hydration status with nephrolithiasis risk at the population level. DESIGN: It is a cross-sectional study in which daily total plain water intake and total fluid intake were estimated together with blood osmolality, urine creatinine, urine osmolality, urine flow rate (UFR), free water clearance (FWC) and urine/blood osmolality ratio (Uosm:Bosm). The associations of fluid intake and hydration markers with nephrolithiasis were evaluated using multivariable logistic regression. SETTING: General US population. PARTICIPANTS: A total of 8195 adults aged 20 years or older from the National Health and Nutritional Examination Survey 2009-2012 cycles. RESULTS: The population medians (interquartile ranges, IQR) for daily total plain water intake and total fluid intake were 807 (336-1481) and 2761 (2107-3577) ml/d, respectively. The adjusted OR (95 % CI) of nephrolithiasis for each IQR increase in total plain water intake and total fluid intake were 0·92 (95 % CI 0·79, 1·06) and 0·84 (95 % CI 0·72, 0·97), respectively. The corresponding OR of nephrolithiasis for UFR, blood osmolality, Uosm:Bosm and urine creatinine were 0·87 (95 % CI 0·76, 0·99), 1·18 (95 % CI 1·06, 1·32), 1·38 (95 % CI 1·17, 1·63) and 1·27 (95 % CI 1·11, 1·45), respectively. A linear protective relationship of fluid intake, UFR and FWC with nephrolithiasis risk was observed. Similarly, positive dose-response associations of nephrolithiasis risk with markers of insufficient hydration were identified. Encouraging a daily water intake of >2500 ml/d and maintaining a urine output of 2 l/d was associated with a lower prevalence of nephrolithiasis. CONCLUSION: This study verified the beneficial role of general water intake recommendations in nephrolithiasis prevention in the general US population.

Elliptical and linear relationships with rumen temperature support a homeorhetic trajectory for DMI during recovery of feedlot cattle exposed to moderate heat load.

Most feedlot animals in Australia experience 2 to 3 moderate heat waves during summer. This study aimed to gain understanding of the physiological drivers in response to and during recovery from such events with a view to designing strategies to ensure rapid and safe recovery. Two hypotheses were tested during thermal challenge and recovery in climate-controlled rooms (CCR): firstly, the feedlot steer on a grain-based diet mounts appropriate physiological responses during moderate heat load and in recovery so that its performance and physiology state after recovery is not different to the feed restricted thermoneutral (FRTN) steer. Secondly, commonly used indicators of increased heat load, e.g., respiration rate (RR), panting score (PS), body surface temperatures (ST), and water consumption (WC), reflect rumen temperature (RT) during thermal challenge and recovery at the level of daily means. In this study, 36 Angus steers (live weight (LW) 451.5 ± 22.6 kg) made up 3 cohorts of 12 animals that sequentially underwent the CCR phase. For this 18-d phase, the steers were allocated to either a moderate heat load treatment (thermally challenged, TC, n = 18) or a FRTN treatment (n = 18). The TC group underwent 3 periods, Pre-Challenge (4 d, temperature humidity index (THI) range of 68 to 71), Challenge (7 d, THI 73 to 84 with diurnal cycling), and Recovery (7 d, THI 68 to 71). The FRTN group were held at thermoneutral conditions in the CCR (THI 66.9 ± 0.3), and each animal was offered an amount of feed was based on the feed intake of its LW matched TC pair. Thus, as DMI fell in the TC group during Challenge, feed restriction was imposed on the FRTN group. The data were collected by trained observers were DMI, RT, RR, PS, body STs (forehead, shoulder, leg, rump), and WC. Challenge induced a heat stress response in the TC group with reduced DMI and LW, and elevated RT, RR, PS, body STs, and WC (P < 0.001). These measures were unchanged or reduced in the FRTN group (P < 0.001). At the end of Recovery, the TC and FRTN groups had converged on most measures including LW. Daily mean RT of both groups showed strong linear relationships with THI, RR, PS, head ST, and WC (P ≤ 0.0022) but opposing elliptical relationships with DMI; that is, as DMI fell with increasing RT for the TC group, DMI increased with rising RT for the FRTN group. In all, the feedlot steers in this study demonstrated sufficient homeorhetic capacity to adjust to moderate heat load and recover from it.

Over any summer, most feedlot steers in Australia will encounter 2 to 3 moderate heat waves lasting 5 to 6 d. The ability of these animals to adjust to the hot conditions and recovery from them is not well understood. The advent of obtaining near real-time body (rumen) temperature from feedlot steers has the potential to help feedlot managers, veterinarians and nutritionists make decisions on the handling of feedlots animals during and after heatwaves. Using climate-controlled rooms, this study demonstrated that feedlot steers are physiologically capable of dealing with moderate heatwave conditions. The co-ordinated increases in respiration rate, sweating rate, body surface temperature, and water consumption alongside reduction in feed intake as heat load increases limits the rise in body temperature. By the end of a 7-d recovery period in thermoneutral conditions, the heat stressed steers were not different physiologically and performance-wise from thermoneutral counterparts feeding on a similar amount of food. However, during the recovery period, all animals appeared to be metabolically and physiologically constrained, and did not return to their pre-heatwave feed intake, body temperature or respiration rate. These findings will assist the management of feedlot animals through recovery after a heat wave.

Hemoglobin Video Imaging Detects Differences in Aqueous Outflow Between Eyes With and Without Glaucoma During the Water Drinking Test.

PRCIS: Hemoglobin video imaging (HVI) demonstrates increased aqueous outflow (AO) in response to the water drinking test (WDT) in patients with and without glaucoma. In glaucomatous eyes, increased AO was not sustained, and characteristic flow patterns were seen. PURPOSE: To observe how variations in intraocular pressure (IOP) correlate with the flow of aqueous in episcleral veins. DESIGN: Prospective observational cohort study. PARTICIPANTS: The WDT increased AO into the episcleral venous system in 30 eyes recruited from Sydney Eye Hospital. A comparison was made between glaucomatous (n=20) and nonglaucomatous eyes (n=10). METHODS: Each patient had baseline IOP and HVI before drinking 10 mL/kg body weight of water. IOP and HVI were then repeated every 15 minutes for 1 hour. Aqueous column cross-sectional area (AqCA) of the most prominent nasal and temporal aqueous veins was used to semi-quantify conventional AO. MAIN OUTCOME MEASURES: Change in IOP and AqCA from baseline during the WDT. Aqueous flow characteristics were also observed. RESULTS: Peak IOP elevation above baseline was significantly higher in the glaucoma group, with an average IOP rise of 39.7% on 1.6 1.1 medications, compared with 22.9% in the control group ( P =0.04). AqCA significantly increased for glaucomatous and nonglaucomatous eyes in response to water ingestion ( P <0.05). AqCA fell by 50% in glaucomatous eyes ( P =0.003) and 33% in nonglaucomatous eyes ( P =0.08) at study completion compared with the peak measurement. IOP remained >30% elevated in 8 glaucomatous eyes (40%) after 60 minutes and no control eyes. Variations in qualitative aqueous flow patterns were observed in glaucomatous eyes but not in controls. CONCLUSIONS: AO volume, estimated by AqCA, increases in response to IOP elevation induced by an ingested water bolus in patients with and without glaucoma. The increase in aqueous drainage was not sustained in glaucomatous eyes and may have led to incomplete recovery of IOP. Using HVI in combination with the WDT may assist with clinical decision-making and facilitate the monitoring of responses to treatment.

Sensitivity of ponies to sodium in the drinking water.

Horses lose high amounts of Na through excessive sweating. These fluid losses can often not be replaced completely by voluntary water intake, requiring saline solutions as rehydration therapy to regain electrolyte balance. The experiment aimed to evaluate the sensitivity and tolerance of Shetland ponies towards different Na concentrations in their drinking water and contained three phases: (1) control: only fresh water provided; (2) pairwise-preference test: choice between fresh water and saline solution with stepwise increasing sodium chloride (NaCl) concentration (0.25%, 0.5%, 0.75%, 1.0%, 1.25%, or 1.5%); and (3) free-choice test: six simultaneously provided buckets containing NaCl concentrations of 0%, 0.25%, 0.5%, 0.75%, 1.0%, or 1.25%. During the pairwise test, the ponies did not distinguish between fresh and 0.25% NaCl-water but demonstrated clear preference for 0.5%, whereas >0.75% NaCl was avoided/rejected. During the free-choice test, a pronounced preference of fresh over saline water was exhibited. The Na intake via salt lick was not reduced as response to higher Na intakes via water. The ponies exhibited a remarkable sensory discrimination capacity to detect different NaCl concentrations in their drinking water. The acceptance of solutions with low NaCl levels (0.25/0.5%) without adverse effects demonstrates potential as rehydration solution for voluntary intake.

Changes in Dietary Intake Patterns and Weight Status during the COVID-19 Lockdown: A Cross-Sectional Study Focusing on Young Adults in Malaysia.

INTRODUCTION: The coronavirus disease 2019 (COVID-19) isolation has altered individuals' food purchasing behaviour and dietary intake patterns. Therefore, this study aims to investigate the changes in dietary intake patterns and their impacts on the weight status of young adults in Malaysia during the COVID-19 lockdown. METHODS: This cross-sectional study involved 1045 young adults in Malaysia. The changes in dietary intake patterns were assessed using the Dietary Diversity Questionnaire with slight modifications, while anthropometric measurements including body height, body weight before the pandemic and current body weight were self-reported. RESULTS: Overall, nearly half of the respondents (48.8%) gained weight during the confinement, with an average increment of 4.06 ± 3.23 kg. Of 1045, 45.3% reported consuming more fruits and 60.2% had higher plain water intake during the pandemic. It is observed that 41.0% to 66.8% of the young adults changed their dietary intake patterns during the pandemic. Increased consumption in cereals and grains (ß = 0.084, p = 0.015, 95% CI = 0.017-0.160), as well as oils and fats (ß = 0.123, p = 0.001, 95% CI = 0.059-0.241), was positively associated with weight gain during the pandemic. On the contrary, an increased plain water intake was negatively associated with weight gain during the lockdown (ß = -0.100, p = 0.003, 95% CI = -0.171--0.034). Findings in the current study also suggested that cutting back cereals and grains (ß = 0.156, p < 0.001, 95% CI = 0.122-0.288), as well as oils and fats (ß = 0.091, p = 0.012, 95% CI = 0.022-0.183), contributed significantly to weight loss during the pandemic confinement. CONCLUSION: In conclusion, the enforcement of the Movement Control Order (MCO) drove up the prevalence of overweight/obesity among young adults in Malaysia. Increased consumption of cereals and grains and oils and fats contributed to weight gain in the pandemic lockdown. Nonetheless, a noticeable proportion of young adults in Malaysia shifted to a healthier food choice by increasing the consumption of fruits and vegetables.

Intestinal ion regulation exhibits a daily rhythm in Gymnocypris przewalskii exposed to high saline and alkaline water.

Naked carp (Gymnocypris przewalskii), endemic to the saline-alkaline Lake Qinghai, have the capacity to tolerate combinations of high salinity and alkalinity, but migrate to spawn in freshwater rivers each year. In this study, we measured the drinking rate over a 24 h period for naked carp exposed to saline-alkaline lake waters with salinities of 15 (L15) and 17 (L17). We also assessed the daily feed intakes of naked carp exposed to L15 and fresh water (FW). Additionally, we studied the daily expression of acid-base regulation and osmoregulation related genes and proteins in the intestine of naked carp exposed to saline-alkaline lake waters. Our results revealed that the drinking rate at night was significantly higher than in daytime when exposed to either L15 or L17, while feed intakes in daytime were significantly higher than at night. The relative expression of Na+/K+-ATPase α (NKA-α), solute carrier family members 26A6 (SLC26A6) and 4A4 (SLC4A4) in the intestine of naked carp exposed to L17 at night was higher than in daytime. Specifically, NKA-α mRNA expression at 4:00 was 7.22-fold and 5.63-fold higher than that at 10:00 and 16:00, respectively, and the expression at 22:00 was 11.29-fold and 8.80-fold higher than that at 10:00 and 16:00, respectively. Similarly, SLC26A6 mRNA expression was greatest at 22:00, exceeding that observed at 4:00, 10:00 and 16:00 by 3.59, 4.44 and 11.14-fold, respectively. Finally, the expression of NKA-α and SLC26A6 protein at the single cell level was also higher at night than during the day, which was 1.65-fold and 1.37-fold higher at 22:00 respectively compared to 16:00. Overall, the present findings revealed that naked carp drinks at night and feeds during the day, demonstrating that intestinal ion regulation exhibits a daily rhythm when exposed to high saline and alkaline lake water.