The role of cellular hydration in the regulation of cell function

Dietary guanidinoacetate reduces spaghetti meat myopathy risk in the breast muscle of broiler chickens

The global demand for white chicken meat along with the increase in the occurrence of growth-related breast muscle myopathies (BMMs) [namely white striping (WS), wooden breast (WB), and spaghetti meat (SM)] highlights the need for solutions that will improve meat quality while maintaining the high productivity of modern broilers. Guanidinoacetate (GAA), a precursor of creatine, is used as a feed additive and has previously shown the potential to affect the quality of breast meat. This study investigated growth performance, meat quality and the risk ratio for the development of BMMs in broilers assigned to two dietary treatments: control (CON) group, fed a commercial basal diet, and supplemented GAA (sGAA) group, receiving the control diet supplemented on top with 0.06% GAA. Growth performance indicators such as BW, daily weight gain, daily feed intake, feed conversion ratio and cumulative feed conversion ratio were recorded on a pen basis. As a trait affecting animal welfare, the occurrence of foot pad dermatitis was also evaluated. At day 43, birds were processed, and breasts were scored for the incidence and severity of BMMs (n = 166 and 165 in CON and sGAA groups, respectively). Quality traits (ultimate pH, colour) and technological properties (i.e., drip and cooking losses, marinade uptake, shear force, and oxidation levels of the lipid and the protein fractions) of breast meat were assessed in both treatments on samples not showing any macroscopic sign of BMMs (n = 20 breast fillets per group). Data of myopathy risk ratio were analysed as the risk for each group to develop WS, WB, and SM myopathies. Our results show that while sGAA and control groups did not differ significantly in growth performance, a remarkably beneficial effect of GAA was observed on the incidence of BMMs with significantly reduced risk of sGAA group to develop SM myopathy. The risk of sGAA group to develop SM was 30% lower compared to CON (P = 0.028). Finally, a significantly lower drip loss was observed in sGAA in comparison with CON (1.78 vs 2.48%, P = 0.020). Together, our results show that the inclusion of 0.06% GAA in feed can improve the water-holding capacity of meat and reduce the risk to develop SM myopathy without compromising the performance of broilers.

Hyponatremia, hypernatremia and impairment of functional, psychological and sexual domains

OBJECTIVE

To determine the influence of serum sodium on physical, psychologic and sexual function.

METHODS

This is a cross-sectional survey on 3340 community-dwelling men aged 40-79 years from a prospective cohort study in eight European countries, the European Male Ageing Study (EMAS). Participants filled-out the Short Form-36 (SF-36), the Physical Activity Scale for the Elderly (PASE), and the EMAS sexual function questionnaire. For all the analyses, serum sodium corrected for glycaemia ([Na+]G) was used.

RESULTS

The relationship between [Na+]G and SF-36 physical function score (F = 3.99; p = 0.01), SF-36 mental health score (F = 7.69; p < 0.001), and PASE score (F = 14.95; p < 0.001) were best described by a quadratic equation, with worse scores for [Na+]G in either the lowest or the highest ends of the range. After dividing the sample into [Na+]G < 136 mmol/L (n = 81), 136-147 mmol/L (n = 3223) and > 147 mmol/L (n = 36), linear regression analyses with linear spline functions adjusted for confounders did not confirm these relationships. Similarly, erectile dysfunction and [Na+]G, were in a quadratic relationship (F = 9.00; p < 0.001). After adjusting for confounders, the linear regression with spline functions denoted a significantly worsened erectile function for increases in serum [Na+]G > 147 mmol/L (B = 0.15 [0.04;0.26], p < 0.01) but no relationship with [Na+]G < 136 mmol/L. Likewise, the relationship of [Na+]G with concerns about sexual dysfunction was confirmed only for men with serum [Na+]G > 147 mmol/L.

CONCLUSIONS

This is the first study supporting an association between [Na+]G and sexual function. A worsening of erection and concerns about sexual function were observed for the highest values of [Na+]G, independently of other relevant factors.

Water restriction increases oxidation of endogenous amino acids in house sparrows (Passer domesticus)

Animals can cope with dehydration in a myriad of ways, both behaviorally and physiologically. The oxidation of protein produces more metabolic water per kilojoule than that of fat or carbohydrate, and it is well established that birds increase protein catabolism in response to high rates of water loss. However, the fate of amino acids mobilized in response to water restriction has not been explicitly determined. While protein catabolism releases bound water, we hypothesized that water-restricted birds would also oxidize the resulting amino acids, producing additional water as a product of oxidative phosphorylation. To test this, we fed captive house sparrows (Passer domesticus) 13C-labeled leucine for 9 weeks to label endogenous proteins. We conducted weekly trials during which we measured the physiological response to water restriction as changes in lean mass, fat mass, metabolism and the enrichment of 13C in exhaled CO2 (δ13Cbreath). If water-restricted birds catabolized proteins and oxidized the resulting amino acids, we expected to simultaneously observe greater lean mass loss and elevated δ13Cbreath relative to control birds. We found that water-restricted birds catabolized more lean tissue and also had enriched δ13Cbreath in response to water restriction, supporting our hypothesis. δ13Cbreath, however, varied with metabolic rate and the length of the water restriction period, suggesting that birds may spare protein when water balance can be achieved using other physiological strategies.

Chirality-Selected Coacervate by Chiral Gemini Surfactant

Chiral surfactants present opportunities to self-assemble into supramolecules with a chiral trait; however, the effects of stereochemistry on the formation of simple coacervates remain unclear. Here, we investigate the chirality-selected phase behavior in mixtures of chiral gemini surfactant 1,4-bis(dodecyl-N,N-dimethylammonium bromide)-2,3-butanediol (12-4(OH)2-12) with an oppositely charged chiral mandelic acid (MA). It demonstrates that altering the chirality of surfactants yields a heightened ability to regulate the phase behavior, leading to the formation of three different network-like structures, i.e., wormlike micelle, coacervate, and hydrogel, in the racemate, enantiomer, and mesomer, respectively. The different aggregate structures arise from the intermolecular and intramolecular hydrogen-bond interactions of the two hydroxyl groups located at stereogenic centers. Intriguingly, although they contain similar microstructures, the solid-like hydrogel and liquid-like wormlike micelle show similar low hydration ability and have no encapsulation capability, whereas only coacervate formed by the enantiomers of 12-4(OH)2-12 displays liquid-like characteristics, strong capacity to sequester diverse solutes, and high affinity for tightly bound water simultaneously. These findings further highlight the unique and advantageous properties of coacervates as a promising model for exploring the biological process and understanding how chirality plays a crucial role in early life scenarios and cell evolution at the molecular level.

International society of sports nutrition position stand: energy drinks and energy shots

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature regarding the effects of energy drink (ED) or energy shot (ES) consumption on acute exercise performance, metabolism, and cognition, along with synergistic exercise-related performance outcomes and training adaptations. The following 13 points constitute the consensus of the Society and have been approved by the Research Committee of the Society: Energy drinks (ED) commonly contain caffeine, taurine, ginseng, guarana, carnitine, choline, B vitamins (vitamins B1, B2, B3, B5, B6, B9, and B12), vitamin C, vitamin A (beta carotene), vitamin D, electrolytes (sodium, potassium, magnesium, and calcium), sugars (nutritive and non-nutritive sweeteners), tyrosine, and L-theanine, with prevalence for each ingredient ranging from 1.3 to 100%. Energy drinks can enhance acute aerobic exercise performance, largely influenced by the amount of caffeine (> 200 mg or >3 mg∙kg bodyweight [BW-1]) in the beverage. Although ED and ES contain several nutrients that are purported to affect mental and/or physical performance, the primary ergogenic nutrients in most ED and ES based on scientific evidence appear to be caffeine and/or the carbohydrate provision. The ergogenic value of caffeine on mental and physical performance has been well-established, but the potential additive benefits of other nutrients contained in ED and ES remains to be determined. Consuming ED and ES 10-60 minutes before exercise can improve mental focus, alertness, anaerobic performance, and/or endurance performance with doses >3 mg∙kg BW-1. Consuming ED and ES containing at least 3 mg∙kg BW-1 caffeine is most likely to benefit maximal lower-body power production. Consuming ED and ES can improve endurance, repeat sprint performance, and sport-specific tasks in the context of team sports. Many ED and ES contain numerous ingredients that either have not been studied or evaluated in combination with other nutrients contained in the ED or ES. For this reason, these products need to be studied to demonstrate efficacy of single- and multi-nutrient formulations for physical and cognitive performance as well as for safety. Limited evidence is available to suggest that consumption of low-calorie ED and ES during training and/or weight loss trials may provide ergogenic benefit and/or promote additional weight control, potentially through enhanced training capacity. However, ingestion of higher calorie ED may promote weight gain if the energy intake from consumption of ED is not carefully considered as part of the total daily energy intake. Individuals should consider the impact of regular coingestion of high glycemic index carbohydrates from ED and ES on metabolic health, blood glucose, and insulin levels. Adolescents (aged 12 through 18) should exercise caution and seek parental guidance when considering the consumption of ED and ES, particularly in excessive amounts (e.g. > 400 mg), as limited evidence is available regarding the safety of these products among this population. Additionally, ED and ES are not recommended for children (aged 2-12), those who are pregnant, trying to become pregnant, or breastfeeding and those who are sensitive to caffeine. Diabetics and individuals with preexisting cardiovascular, metabolic, hepatorenal, and/or neurologic disease who are taking medications that may be affected by high glycemic load foods, caffeine, and/or other stimulants should exercise caution and consult with their physician prior to consuming ED. The decision to consume ED or ES should be based upon the beverage's content of carbohydrate, caffeine, and other nutrients and a thorough understanding of the potential side effects. Indiscriminate use of ED or ES, especially if multiple servings per day are consumed or when consumed with other caffeinated beverages and/or foods, may lead to adverse effects. The purpose of this review is to provide an update to the position stand of the International Society of Sports Nutrition (ISSN) integrating current literature on ED and ES in exercise, sport, and medicine. The effects of consuming these beverages on acute exercise performance, metabolism, markers of clinical health, and cognition are addressed, as well as more chronic effects when evaluating ED/ES use with exercise-related training adaptions.

Hydration, Hyperthermia, Glycogen, and Recovery: Crucial Factors in Exercise Performance-A Systematic Review and Meta-Analysis

Hyperthermia accelerates dehydration and can lead to a glycolysis malfunction. Therefore, to deeply understand the relationship between dehydration and hyperthermia during exercise, as well as in the recovery time, there might be important factors to improve athletic performance. A systematic review was carried out in different databases using the words "hydration" OR "dehydration" AND "glycogen" OR "glycogenesis" OR "glycogenolysis" AND "muscle" OR "muscle metabolism" OR "cardiovascular system" and adding them to the "topic section" in Web of Science, to "Title/Abstract" in PubMed and to "Abstract" in SPORTDiscus. A total of 18 studies were included in the review and 13 in the meta-analysis. The free statistical software Jamovi was used to run the meta-analysis (version 1.6.15). A total sample of 158 people was included in the qualitative analysis, with a mean age of 23.5 years. Ten studies compared muscle glycogen content after hydration vs. remaining dehydrated (SMD -4.77 to 3.71, positive 80% of estimates, \hat{\mu} = 0.79 (95% CI: -0.54 to 2.12), z = 1.17, p = 0.24, Q-test (Q(9) = 66.38, p < 0.0001, tau2 = 4.14, I2 = 91.88%). Four studies examined the effect of temperature on postexercise muscle glycogen content (SMD -3.14 to -0.63, 100% of estimates being negative, \hat{\mu} = -1.52 (95% CI: -2.52 to -0.53), (z = -3.00, p = 0.003, Q-test (Q(3) = 8.40, p = 0.038, tau2 = 0.68, I2 = 66.81%). In conclusion, both hyperthermia and dehydration may contribute to elevated glycogenolysis during exercise and poor glycogen resynthesis during recovery. Although core and muscle hyperthermia are the key factors in glycogen impairments, they are also directly related to dehydration.

ESPEN guideline on chronic intestinal failure in adults - Update 2023

BACKGROUND & AIMS

In 2016, ESPEN published the guideline for Chronic Intestinal Failure (CIF) in adults. An updated version of ESPEN guidelines on CIF due to benign disease in adults was devised in order to incorporate new evidence since the publication of the previous ESPEN guidelines.

METHODS

The grading system of the Scottish Intercollegiate Guidelines Network (SIGN) was used to grade the literature. Recommendations were graded according to the levels of evidence available as A (strong), B (conditional), 0 (weak) and Good practice points (GPP). The recommendations of the 2016 guideline (graded using the GRADE system) which were still valid, because no studies supporting an update were retrieved, were reworded and re-graded accordingly.

RESULTS

The recommendations of the 2016 guideline were reviewed, particularly focusing on definitions, and new chapters were included to devise recommendations on IF centers, chronic enterocutaneous fistulas, costs of IF, caring for CIF patients during pregnancy, transition of patients from pediatric to adult centers. The new guideline consist of 149 recommendations and 16 statements which were voted for consensus by ESPEN members, online in July 2022 and at conference during the annual Congress in September 2022. The Grade of recommendation is GPP for 96 (64.4%) of the recommendations, 0 for 29 (19.5%), B for 19 (12.7%), and A for only five (3.4%). The grade of consensus is "strong consensus" for 148 (99.3%) and "consensus" for one (0.7%) recommendation. The grade of consensus for the statements is "strong consensus" for 14 (87.5%) and "consensus" for two (12.5%).

CONCLUSIONS

It is confirmed that CIF management requires complex technologies, multidisciplinary and multiprofessional activity, and expertise to care for the underlying gastrointestinal disease and to provide HPN support. Most of the recommendations were graded as GPP, but almost all received a strong consensus.

ADAPTations to low load blood flow restriction exercise versus conventional heavier load resistance exercise in UK military personnel with persistent knee pain: protocol for the ADAPT study, a multi-centre randomized controlled trial

BACKGROUND

Muscle atrophy, muscle weakness and localised pain are commonly reported following musculoskeletal injury (MSKI). To mitigate this risk and prepare individuals to return to sport or physically demanding occupations, resistance training (RT) is considered a vital component of rehabilitation. However, to elicit adaptations in muscle strength, exercise guidelines recommend lifting loads ≥ 70% of an individual's one repetition maximum (1-RM). Unfortunately, individuals with persistent knee pain are often unable to tolerate such high loads and this may negatively impact the duration and extent of their recovery. Low load blood flow restriction (LL-BFR) is an alternative RT technique that has demonstrated improvements in muscle strength, hypertrophy, and pain in the absence of high mechanical loading. However, the effectiveness of high-frequency LL-BFR in a residential rehabilitation environment remains unclear. This study will compare the efficacy of high frequency LL-BFR to 'conventional' heavier load resistance training (HL-RT) on measures of physical function and pain in adults with persistent knee pain.

METHODS

This is a multicentre randomised controlled trial (RCT) of 150 UK service personnel (aged 18-55) admitted for a 3-week residential rehabilitation course with persistent knee pain. Participants will be randomised to receive: a) LL-BFR delivered twice daily at 20% 1-RM or b) HL-RT three-times per week at 70% 1-RM. Outcomes will be recorded at baseline (T1), course discharge (T2) and at three-months following course (T3). The primary outcome will be the lower extremity functional scale (LEFS) at T2. Secondary outcomes will include patient reported perceptions of pain, physical and occupational function and objective measures of muscle strength and neuromuscular performance. Additional biomechanical and physiological mechanisms underpinning both RT interventions will also be investigated as part of a nested mechanistic study.

DISCUSSION

LL-BFR is a rehabilitation modality that has the potential to induce positive clinical adaptations in the absence of high mechanical loads and therefore could be considered a treatment option for patients suffering significant functional deficits who are unable to tolerate heavy load RT. Consequently, results from this study will have a direct clinical application to healthcare service providers and patients involved in the rehabilitation of physically active adults suffering MSKI.

TRIAL REGISTRATION

ClinicalTrials.org reference number, NCT05719922.

Low-Load x High-Load Resistance Exercise: Greater Cell Swelling After a Training Session

Cell swelling caused by resistance training is proposed to provide an anabolic stimulus for muscle growth and it is believed that these effects are heightened with the use of low loads. The purpose of this study was to compare the acute effects of two volume-equated resistance training (RT) protocols, low-load (LL) versus high-load (HL), on elbow flexor muscles thickness, arm circumference, and blood lactate concentration in well-trained individuals. Eight resistance-trained males performed the following two RT protocols involving unilateral elbow flexion of the dominant arm: i) LL, four sets with 50% 1 repetition-maximum [1 RM] and ii) HL, ten sets with 85% 1 RM until failure, and equated volume. Pre- and post-session measurements included muscle thickness of the elbow flexors (biceps brachii and brachialis), upper arm circumference, and blood lactate concentration. Significant pre- to post-session increases were found in both protocols for muscle thickness (F (1, 28) = 11.74, p = 0.0019), and blood lactate (F (1, 28) = 35.55, p < 0.0001); no statistically significant differences were observed between conditions, however, the magnitude of increases favored LL. Significant between-condition differences favoring LL were observed for total repetitions (p = 0.007), time under tension (p = 0.007), and training density (p = 0.007). These results suggest that LL training promotes superior post-session increases in muscle thickness, indicating that RT protocols with longer times under tension and densities are beneficial when the goal is to promote acute cell swelling.

A Study of the Fluid Intake, Hydration Status, and Health Effects among Pregnant Women in Their Second Trimester in China: A Cross-Sectional Study

The fluid intake and hydration status during pregnancy may influence the health outcomes of both the mother and the fetus. However, there are few studies related to this. The aim of the present study was to investigate fluid intake behaviors among pregnant women in their second trimester, to evaluate their hydration status and pregnancy complications, and to further explore the association of fluid intake and the amniotic fluid index (AFI). Participants’ total fluid intake (TFI) levels were determined using a 7-day 24 h fluid intake questionnaire. The levels of water intake from food were not recorded or measured. Morning urine samples were collected, and both urine osmolality levels and urine specific gravity (USG) were tested to evaluate their hydration status. Fasting blood samples were also collected and measured for osmolality and complete blood count (CBC). A total of 324 participants completed the study. They were divided into four groups based on quartiles of TFI, including participants with lower (LFI1 and LFI2) and higher (HFI1 and HFI2) fluid intake levels. The median TFI was 1485 mL, and the median values of the four groups with different TFI levels were 1348, 1449, 1530, and 1609 mL, respectively. Only 3.4% of the participants attained the recommended value following an adequate water intake (1.7 L) level for pregnant women in China. Plain water was the main TFI resource (78.8~100.00%), and differences in the plain water intake levels among the four groups were evident (χ2 = 222.027, p < 0.05). The urine osmolality decreased sequentially with increasing TFI values from the LFI1 to HFI2 group, and significant differences in the urine osmolality levels among the four groups were evident (p < 0.05). Meanwhile, the percentage of dehydrated participants decreased from 26.8% in the LFI1 group to 0.0% in the HFI2 group (χ2 = 131.241, p < 0.05). Participants with higher TFI values had higher AFI values (χ2 = 58.386, all p < 0.05), and moderate-intensity correlations were found between TFI and urine osmolality, hydration status, and AFI (all p < 0.05). A large proportion of the participants had insufficient TFIs during the second trimester of pregnancy, and a proportion of the participants were dehydrated. The preliminary analysis showed that the AFI was correlated with the TFI during the second trimester of pregnancy. A sufficient TFI is necessary for pregnant women to improve their hydration status and may have effects on their health. The results can provide appropriate scientific references for the development of beneficial recommendations concerning adequate water intake levels for pregnant women in China.

Phase angle, muscle tissue, and resistance training

The biophysical response of the human body to electric current is widely appreciated as a barometer of fluid distribution and cell function. From distinct raw bioelectrical impedance (BIA) variables assessed in the field of body composition, phase angle (PhA) has been repeatedly indicated as a functional marker of the cell's health and mass. Although resistance training (RT) programs have demonstrated to be effective to improve PhA, with varying degrees of change depending on other raw BIA variables, there is still limited research explaining the biological mechanisms behind these changes. Here, we aim to provide the rationale for the responsiveness of PhA determinants to RT, as well as to summarize all available evidence addressing the effect of varied RT programs on PhA of different age groups. Available data led us to conclude that RT modulates the cell volume by increasing the levels of intracellular glycogen and water, thus triggering structural and functional changes in different cell organelles. These alterations lead, respectively, to shifts in the resistive path of the electric current (resistance, R) and capacitive properties of the human body (reactance, Xc), which ultimately impact PhA, considering that it is the angular transformation of the ratio between Xc and R. Evidence drawn from experimental research suggests that RT is highly effective for enhancing PhA, especially when adopting high-intensity, volume, and duration RT programs combining other types of exercise. Still, additional research exploring the effects of RT on whole-body and regional BIA variables of alternative population groups is recommended for further knowledge development.

Creatine Supplementation to Improve Sarcopenia in Chronic Liver Disease: Facts and Perspectives

Creatine supplementation has been one of the most studied and useful ergogenic nutritional support for athletes to improve performance, strength, and muscular mass. Over time creatine has shown beneficial effects in several human disease conditions. This review aims to summarise the current evidence for creatine supplementation in advanced chronic liver disease and its complications, primarily in sarcopenic cirrhotic patients, because this condition is known to be associated with poor prognosis and outcomes. Although creatine supplementation in chronic liver disease seems to be barely investigated and not studied in human patients, its potential efficacy on chronic liver disease is indirectly highlighted in animal models of non-alcoholic fatty liver disease, bringing beneficial effects in the fatty liver. Similarly, encephalopathy and fatigue seem to have beneficial effects. Creatine supplementation has demonstrated effects in sarcopenia in the elderly with and without resistance training suggesting a potential role in improving this condition in patients with advanced chronic liver disease. Creatine supplementation could address several critical points of chronic liver disease and its complications. Further studies are needed to support the clinical burden of this hypothesis.

Differential expression of aquaporin genes and the influence of environmental hypertonicity on their expression in juveniles of air-breathing stinging catfish (Heteropneustes fossilis)

Aquaporins (AQPs) are a superfamily of transmembrane channel proteins that are responsible for the transport of water and some other molecules to and from the cell, mainly for osmoregulation under anisotonicity. We investigated here the expression patterns of different AQP isoforms and also during exposure to hypertonicity (300 mOsmol/L) for 48 h in juvenile stages of air-breathing stinging catfish (Heteropneustes fossilis). A total of 8 mRNA transcripts for different isoforms of AQPs and their translated proteins could be detected in the anterior and posterior regions of S1, S2, and S3 stages of juveniles of stinging catfish at variable levels. In general, more expression of mRNAs for different aqp genes was seen in the S2 and S3 juveniles than in the S1 juveniles. Most interestingly, exposure to hypertonicity of S2 juveniles for a period of 48 h led to increased expression of most of the aqp genes both at transcriptional and translational levels, except for aqp3 in the anterior and posterior regions and aqp1 in the anterior region, showing maximum expression at later stages of hypertonic exposure. Thus, it is evident that AQPs play crucial roles in maintaining the water and ionic balances under anisotonic conditions even at the early developmental stages of stinging catfish as a biochemical adaptational strategy to survive and grow in anisotonic environment.

AFM Microfluidic Cantilevers as Weight Sensors for Live Single Cell Mass Measurements

Reliably measuring small mass changes at the single-cell level is challenging. In this manuscript, we report the use of microfluidic cantilevers in liquid with sub-nanogram scale weight sensing capability for the measurement of cellular mass changes of living single cells. With this instrumentation, we were able to perform fast mass measurements within 3 minutes. We show results of mass measurements of polystyrene and metal beads of various sizes (smallest weight measured at 280 ± 95 pg) and live single-cell mass measurements in a physiologically relevant environment. We also performed finite element analysis to simulate and optimize the structural design and materials of cantilevers. Our simulation results indicate that using polymer materials, such as SU8 and polyimide, could improve the minimal detectable mass by 3-fold compared to conventional silicon cantilevers. The simulations also suggest that smaller dimensions of length, width, and thickness would improve the mass detection capability of microfluidic cantilevers.

High-resolution mass measurements of single budding yeast reveal linear growth segments

The regulation of cell growth has fundamental physiological, biotechnological and medical implications. However, methods that can continuously monitor individual cells at sufficient mass and time resolution hardly exist. Particularly, detecting the mass of individual microbial cells, which are much smaller than mammalian cells, remains challenging. Here, we modify a previously described cell balance ('picobalance') to monitor the proliferation of single cells of the budding yeast, Saccharomyces cerevisiae, under culture conditions in real time. Combined with optical microscopy to monitor the yeast morphology and cell cycle phase, the picobalance approaches a total mass resolution of 0.45 pg. Our results show that single budding yeast cells (S/G2/M phase) increase total mass in multiple linear segments sequentially, switching their growth rates. The growth rates weakly correlate with the cell mass of the growth segments, and the duration of each growth segment correlates negatively with cell mass. We envision that our technology will be useful for direct, accurate monitoring of the growth of single cells throughout their cycle.

Extending applications of AFM to fluidic AFM in single living cell studies

In this article, a review of a series of applications of atomic force microscopy (AFM) and fluidic Atomic Force Microscopy (fluidic AFM, hereafter fluidFM) in single-cell studies is presented. AFM applications involving single-cell and extracellular vesicle (EV) studies, colloidal force spectroscopy, and single-cell adhesion measurements are discussed. FluidFM is an offshoot of AFM that combines a microfluidic cantilever with AFM and has enabled the research community to conduct biological, pathological, and pharmacological studies on cells at the single-cell level in a liquid environment. In this review, capacities of fluidFM are discussed to illustrate (1) the speed with which sequential measurements of adhesion using coated colloid beads can be done, (2) the ability to assess lateral binding forces of endothelial or epithelial cells in a confluent cell monolayer in an appropriate physiological environment, and (3) the ease of measurement of vertical binding forces of intercellular adhesion between heterogeneous cells. Furthermore, key applications of fluidFM are reviewed regarding to EV absorption, manipulation of a single living cell by intracellular injection, sampling of cellular fluid from a single living cell, patch clamping, and mass measurements of a single living cell.

Increase in the Intracellular Bulk Water Content in the Early Phase of Cell Death of Keratinocytes, Corneoptosis, as Revealed by 65 GHz Near-Field CMOS Dielectric Sensor

While bulk water and hydration water coexist in cells to support the expression of biological macromolecules, how the dynamics of water molecules, which have long been only a minor role in molecular biology research, relate to changes in cellular states such as cell death has hardly been explored so far due to the lack of evaluation techniques. In this study, we developed a high-precision measurement system that can discriminate bulk water content changes of ±0.02% (0.2 mg/cm³) with single-cell-level spatial resolution based on a near-field CMOS dielectric sensor operating at 65 GHz. We applied this system to evaluate the temporal changes in the bulk water content during the cell death process of keratinocytes, called corneoptosis, using isolated SG1 (first layer of stratum granulosum) cells in vitro. A significant irreversible increase in the bulk water content was observed approximately 1 h before membrane disruption during corneoptosis, which starts with cytoplasmic high Ca²⁺ signal. These findings suggest that the calcium flux may have a role in triggering the increase in the bulk water content in SG1 cells. Thus, our near-field CMOS dielectric sensor provides a valuable tool to dissect the involvement of water molecules in the various events that occur in the cell.

Swelling-induced upregulation of miR-141-3p inhibits hepatocyte proliferation

Background & Aims

Methods

Results

Conclusions

Lay summary

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Gene expression changes in hypoosmotic perfused rat liver.

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Hypoosmolarity upregulates miR-141-3p in rat perfused liver and primary hepatocytes.

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Src-/Erk-/p38-MAPK-inhibition prevents miR-141-3p upregulation by hypoosmolarity.

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PHx and hepatocyte stretch transiently upregulate miR-141-3p, which downregulates Cdk8 mRNA.

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Overexpression of miR-141-3p inhibits Huh7 cell proliferation.

The Important Role of Ion Transport System in Cervical Cancer

Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca²⁺ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl⁻ channels and K⁺-Cl⁻ cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca²⁺ homeostasis, the Ca²⁺ store sensor STIM molecules and plasma membrane Ca²⁺ channel Orai proteins, the predominant Ca²⁺ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.

Disentangling environmental drivers of circadian metabolism in desert-adapted mice

Metabolism is a complex phenotype shaped by natural environmental rhythms, as well as behavioral, morphological and physiological adaptations. Metabolism has been historically studied under constant environmental conditions, but new methods of continuous metabolic phenotyping now offer a window into organismal responses to dynamic environments, and enable identification of abiotic controls and the timing of physiological responses relative to environmental change. We used indirect calorimetry to characterize metabolic phenotypes of the desert-adapted cactus mouse (Peromyscus eremicus) in response to variable environmental conditions that mimic their native environment versus those recorded under constant warm and constant cool conditions, with a constant photoperiod and full access to resources. We found significant sexual dimorphism, with males being more prone to dehydration than females. Under circadian environmental variation, most metabolic shifts occurred prior to physical environmental change and the timing was disrupted under both constant treatments. The ratio of CO2 produced to O2 consumed (the respiratory quotient) reached greater than 1.0 only during the light phase under diurnally variable conditions, a pattern that strongly suggests that lipogenesis contributes to the production of energy and endogenous water. Our results are consistent with historical descriptions of circadian torpor in this species (torpid by day, active by night), but reject the hypothesis that torpor is initiated by food restriction or negative water balance.

Acute changes in muscle thickness, edema, and blood flow are not different between low-load blood flow restriction and non-blood flow restriction

The purpose of the present study was to examine the acute changes in muscle swelling (as assessed by muscle thickness and echo intensity) and muscle blood flow associated with an acute bout of low-load blood flow restriction (LLBFR) and low-load non-blood flow restriction (LL) exercise. Twenty women (mean ± SD; 22 ± 2years) volunteered to perform an acute exercise bout that consisted of 75 (1 × 30, 3 × 15) isokinetic, reciprocal, concentric-only, submaximal (30% of peak torque), forearm flexion and extension muscle actions. Pretest, immediately after (posttest), and 5-min after (recovery) completing the 75 repetitions, muscle thickness and echo intensity were assessed from the biceps brachii and triceps brachii muscles and muscle blood flow was assessed from the brachial artery. There were no between group differences for any of the dependent variables, but there were significant simple and main effects for muscle and time. Biceps and triceps brachii muscle thickness increased from pretest (2.13 ± 0.39 cm and 1.88 ± 0.40 cm, respectively) to posttest (2.58 ± 0.49 cm and 2.17 ± 0.43 cm, respectively) for both muscles and remained elevated for the biceps brachii (2.53 ± 0.43 cm), but partially returned to pretest levels for the triceps brachii (2.06 ± 0.41 cm). Echo intensity and muscle blood flow increased from pretest (98.0 ± 13.6 Au and 94.5 ± 31.6 ml min^-1 , respectively) to posttest (109.2 ± 16.9 Au and 312.2 ± 106.5 ml min^-1 , respectively) and pretest to recovery (110.1 ± 18.3 Au and 206.7 ± 92.9 ml min^-1 , respectively) and remained elevated for echo intensity, but partially returned to pretest levels for muscle blood flow. The findings of the present study indicated that LLBFR and LL elicited comparable acute responses as a result of reciprocal, concentric-only, forearm flexion and extension muscle actions.

Association of mean corpuscular volume with sarcopenia and visceral obesity in individuals without anemia

AIMS/INTRODUCTION

Sarcopenia and visceral obesity are major global public health issues, and higher mean corpuscular volume (MCV) levels are related to adverse outcomes. Nevertheless, no study has determined the association between MCV and body composition. Therefore, we evaluated the association between MCV levels and trunk muscle quality, muscle quantity and visceral fat area.

MATERIALS AND METHODS

In our cross-sectional study, we investigated 702 middle-aged Japanese individuals without anemia and with normal MCV levels who underwent physical checkups. The cross-sectional area of skeletal muscle or visceral fat was analyzed by computed tomography.

RESULTS

In the adjusted model, the MCV was independently associated with the visceral fat area index (β = -0.107, P = 0.0007), total skeletal muscle index (β = 0.053, P = 0.0341) and total skeletal muscle density (β = 0.099, P = 0.0012). MCV as a continuous variable was related to the prevalence of sarcopenia (odds ratios [OR] 0.93, 95% confidence intervals (CI) 0.88-0.98, per 1.0 fL increment; P = 0.0097) and visceral obesity (OR 0.91, 95% CI 0.86-0.97, per 1.0 fL increment; P = 0.0046). The highest MCV quartile was independently associated with the prevalence of sarcopenia (OR 0.48, 95% CI 0.27-0.83; P = 0.0089) and visceral obesity (OR 0.49, 95% CI 0.27-0.88; P = 0.0170), compared with the lowest quartile.

CONCLUSIONS

In individuals without anemia and with normal MCV levels, a lower MCV was associated with unfavorable body composition, including lower muscle quality, lower muscle quantity, sarcopenia and visceral obesity.

Liver cell hydration and integrin signaling

Liver cell hydration (cell volume) is dynamic and can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such volume changes were identified as a novel and important modulator of cell function. It provides an early example for the interaction between a physical parameter (cell volume) on the one hand and metabolism, transport, and gene expression on the other. Such events involve mechanotransduction (osmosensing) which triggers signaling cascades towards liver function (osmosignaling). This article reviews our own work on this topic with emphasis on the role of β₁ integrins as (osmo-)mechanosensors in the liver, but also on their role in bile acid signaling.

Hyperreflexia and enhanced ripple oscillations in the taurine-deficient mice

In this study, we examined neuronal excitability and skeletal muscle physiology and histology in homozygous knockout mice lacking cysteine sulfonic acid decarboxylase (CSAD-KO). Neuronal excitability was measured by intracerebral recording from the prefrontal cortex. Skeletal muscle response was measured through stretch reflex in the ankle muscles. Specifically, we measured the muscle tension, amplitude of electromyogram and velocity of muscle response. Stretch reflex responses were evoked using a specialized stretching device designed for mice. The triceps surae muscle was stretched at various speeds ranging from 18 to 18,000° s^-1. A transducer recorded the muscle resistance at each velocity and the corresponding EMG. We also measured the same parameter in anesthetized mice. We found that at each velocity, the CSAD-KO mice generated more tension and exhibited higher EMG responses. To evaluate if the enhanced response was due to neuronal excitability or changes in the passive properties of muscles, we anesthetize mice to eliminate the central component of the reflex. Under these conditions, CSAD-KO mice still exhibited an enhanced stretch reflex response, indicating ultrastructural alterations in muscle histology. Consistent with this, we found that sarcomeres from CSAD-KO muscles were shorter and thinner when compared to control sarcomeres. Neuronal excitability was further investigated using intracerebral recordings of brain waves from the prefrontal cortex. We found that extracellular field potentials in CSAD-KO mice were characterized by reduced amplitude of low-frequency brain waves (delta, theta, alpha, beta and gamma) and increased in the high low-frequency brain waves (slow and fast ripples). Increased slow and fast ripple rates serve as a biomarker of epileptogenic brain. We have previously shown that taurine interacts with GABA_A receptors and induces biochemical changes in the GABAergic system. We suggest that taurine deficiency leads to alterations in the GABAergic system that contribute to the enhanced stretch reflex in CSAD-KO mice through biochemical mechanisms that involve alterations not only at the spinal level but also at the cortical level.

Hippocrates Was Right: Now What? Water As a Part of Healthy Aging

BACKGROUND

Aging is defined as the progressive organism change leading to debility, disease, and death [<xref ref-type="bibr" rid="ref1">1</xref>]. We know that as we age, our risk increases for diseases such as diabetes, cancer, and chronic kidney disease, and many of our homeostatic processes change as well, such as cell signaling, metabolism, and proteostasis [<xref ref-type="bibr" rid="ref2">2</xref>]. The data clearly show that water intake decreases with aging, especially after age 60 years [<xref ref-type="bibr" rid="ref3">3</xref>]. However, the question becomes "Do we drink less because we age, or do we age because we drink less?" (Fig. 1).

SUMMARY

There are data to support both directions of this hypothesis. One example supporting that water intake decreases due to aging is that in older adults, the thirst response to hyperosmotic and hypovolemic stimuli is blunted in comparison to younger adults [<xref ref-type="bibr" rid="ref4">4</xref>]. However, we are increasingly gathering data to also support that low water intake can be a contributor to both disease and altered cellular processes, potentially accelerating aging related dysfunction. For example, in older adults, low water intake has been shown to be associated with working memory [<xref ref-type="bibr" rid="ref5">5</xref>], blood glucose regulation [<xref ref-type="bibr" rid="ref6">6</xref>], incidence of stroke [<xref ref-type="bibr" rid="ref7">7</xref>], and falls [<xref ref-type="bibr" rid="ref8">8</xref>] (i.e., dementia, diabetes, cardiovascular disease, and mobility). Additionally, processes such as metabolism [<xref ref-type="bibr" rid="ref9">9</xref>], cell signaling [<xref ref-type="bibr" rid="ref10">10</xref>], and muscle damage following exercise [<xref ref-type="bibr" rid="ref11">11</xref>] have also been linked to hydration. Key messages are that it is clear that water intake changes as we age, primarily due to changes in thirst. However, what is our duty as hydrationists is to begin to evaluate both directions of the aging, dysfunction, and water intake relationship (Fig. 1). Just as we have begun to realize the influence as water as a nutrient, we can hopefully demonstrate how a simple intervention like drinking to recommendations can be a part of healthy aging for all.

Pannexin 1, a large-pore membrane channel, contributes to hypotonicity-induced ATP release in Schwann cells

Pannexin 1 (Panx 1), as a large-pore membrane channel, is highly permeable to ATP and other signaling molecules. Previous studies have demonstrated the expression of Panx 1 in the nervous system, including astrocytes, microglia, and neurons. However, the distribution and function of Panx 1 in the peripheral nervous system are not clear. Blocking the function of Panx 1 pharmacologically (carbenoxolone and probenecid) or with small interfering RNA targeting pannexins can greatly reduce hypotonicity-induced ATP release. Treatment of Schwann cells with a Ras homolog family member (Rho) GTPase inhibitor and small interfering RNA targeting Rho or cytoskeleton disrupting agents, such as nocodazole or cytochalasin D, revealed that hypotonicity-induced ATP release depended on intracellular RhoA and the cytoskeleton. These findings suggest that Panx 1 participates in ATP release in Schwann cells by regulating RhoA and the cytoskeleton arrangement. This study was approved by the Animal Ethics Committee of Nantong University, China (No. S20180806-002) on August 5, 2018.

A rather dry subject; investigating the study of arid-associated microbial communities

Almost one third of Earth's land surface is arid, with deserts alone covering more than 46 million square kilometres. Nearly 2.1 billion people inhabit deserts or drylands and these regions are also home to a great diversity of plant and animal species including many that are unique to them. Aridity is a multifaceted environmental stress combining a lack of water with limited food availability and typically extremes of temperature, impacting animal species across the planet from polar cold valleys, to Andean deserts and the Sahara. These harsh environments are also home to diverse microbial communities, demonstrating the ability of bacteria, fungi and archaea to settle and live in some of the toughest locations known. We now understand that these microbial ecosystems i.e. microbiotas, the sum total of microbial life across and within an environment, interact across both the environment, and the macroscopic organisms residing in these arid environments. Although multiple studies have explored these microbial communities in different arid environments, few studies have examined the microbiota of animals which are themselves arid-adapted. Here we aim to review the interactions between arid environments and the microbial communities which inhabit them, covering hot and cold deserts, the challenges these environments pose and some issues arising from limitations in the field. We also consider the work carried out on arid-adapted animal microbiotas, to investigate if any shared patterns or trends exist, whether between organisms or between the animals and the wider arid environment microbial communities. We determine if there are any patterns across studies potentially demonstrating a general impact of aridity on animal-associated microbiomes or benefits from aridity-adapted microbiomes for animals. In the context of increasing desertification and climate change it is important to understand the connections between the three pillars of microbiome, host genome and environment.

Dynamic Adjustments of Parenteral Support in Early Adult Intestinal Failure-Essential Role of Sodium

Intestinal failure (IF) requires parenteral support (PS) substituting energy, water, and electrolytes to compensate intestinal losses and replenish deficits. Convalescence, adaptation, and reconstructive surgery facilitate PS reduction. We analyzed the effect of changes of PS on body mass index (BMI) in early adult IF. Energy, volume, and sodium content of PS and BMI were collected at the initial contact (FIRST), the time of maximal PS and BMI (MAX) and the last contact (LAST). Patients were categorized based on functional anatomy: small bowel enterostomy-group 1, jejuno-colic anastomosis-group 2. Analysis of variance was used to test the relative impact of changes in energy, volume, or sodium. Total of 50 patients were followed for 596 days. Although energy, volume, and sodium support were already high at FIRST, we increased PS to MAX, which was accompanied by a significant BMI increase. Thereafter PS could be reduced significantly, leading to a small BMI decrease in group 1, but not in group 2. Increased sodium support had a stronger impact on BMI than energy or volume. Total of 13 patients were weaned. Dynamic PS adjustments are required in the early phase of adult IF. Vigorous sodium support acts as an independent factor.

Direct measurement of K+ ion efflux from neuronal cells using a graphene-based ion sensitive field effect transistor

A graphene-based ion sensitive field effect transistor (GISFET) has been developed and investigated in terms of its ion sensing performance. The GISFET sensor was found to demonstrate a high detection sensitivity enabling direct measurement of K⁺ ion efflux from live cells. The sensing performance of the GISFET was directly compared to that of a commercial Si ISFET and very similar detection results were obtained, highlighting the promise of the GISFET sensor for ion-sensing applications. Additionally, fabrication of a GISFET array containing 25 devices using a CMOS compatible photolithographic process was demonstrated, which resulted in good uniformity across the array and high ion sensing properties of the devices, underlining their application potential for simultaneous multi-well testing with small sample volume.

A graphene-based ISFET has been developed and demonstrated high sensitivity and direct measurement of K⁺ ion efflux from live cells.

Association between serum choline and betaine concentrations and longitudinal changes of body composition in community-dwelling middle-aged and older Chinese adults

Previous studies suggest that betaine and choline may be beneficial for body composition. However, no longitudinal study has been conducted to illustrate if choline and betaine have long-term effects on changes in body composition. This study aimed to prospectively investigate the association between serum choline and betaine concentrations and 3-year changes in body composition in community-dwelling Chinese adults. This present analysis used data from 1384 women and 554 men aged 40–75 years. Serum concentrations of betaine and choline at baseline were assessed using high-performance liquid chromatography-tandem mass spectrometry. Body composition parameters, i.e., muscle mass (MM), fat mass (FM), and body fat percentage (FM%) were measured using dual-energy X-ray absorptiometry at the first and the second follow-ups. After adjustment for potential cofounders, higher serum choline concentrations were associated with a lower decrease in MM in men (β = 0.022, P = 0.025) and a lower increase in FM and FM% in women with baseline choline concentrations below 21.5 μmol/L (all P for nonlinearity = 0.007); higher serum betaine concentrations were associated with a lower decline in MM and a lower increase in FM and FM% among men whose betaine concentrations were lower than 55 μmol/L (all P for nonlinearity < 0.05). These findings suggest that higher concentrations of serum choline and betaine may be associated with favorable changes in body composition profiles among men and women who have relatively low concentrations, especially in men.

Novelty Higher concentrations of serum choline and betaine were associated with favorable changes in body composition. Such favorable associations were more pronounced in men.

Euryhalinity of subtropical marine and estuarine polychaetes evaluated through carbonic anhydrase activity and cell volume regulation

Polychaete worms are widespread and diverse in marine and estuarine habitats subject to varying salinity, in areas influenced by tides, demanding physiological adjustment for internal homeostasis. They are typically considered and reported to be osmoconformers, but they are not often studied for their osmoregulation. Here, three species of polychaete worms from distinct coastal habitats have been investigated: the spionid Scolelepis goodbody (intertidal in saline, exposed sandy beaches), the nereidid Laeonereis culveri (estuarine polyhaline), and the nephtyid Nephtys fluviatilis (estuarine oligohaline). The general objective here was to relate ecological aspects and physiology of the studied species. Constitutive whole body osmolality and carbonic anhydrase activity (CAA, relevant for osmoregulation, acid-base balance and respiration) have been assayed. In addition, cell volume regulatory capacity (from whole body cell dissociation) was challenged under hypoosmotic and hyperosmotic shocks (50% intensity), with respect to isosmotic control. S. googdbody and L. culveri, the two species from most saline environments (marine/estuarine), showed higher CAA than N. fluviatilis, which, in turn, displayed a hyperosmotic gradient to water of salinity 15. Cells from S. goodbody and L. culveri showed regulatory volume decrease upon swelling, with S. goodbody showing the largest volume increase. As in other more studied marine invertebrate groups, polychaetes also show variability in their osmoregulatory physiology, related to distinct saline challenges faced in their coastal habitats.

Tauroursodeoxycholate protects from glycochenodeoxycholate-induced gene expression changes in perfused rat liver

Tauroursodeoxycholate (TUDC) is well known to protect against glycochenodeoxycholate (GCDC)-induced apoptosis in rat hepatocytes. In the present study, we analyzed whether TUDC also exerts protective effects by modulating GCDC-induced gene expression changes. For this, gene array-based transcriptome analysis and quantitative polymerase chain reaction (qPCR) were performed on RNA isolated from rat livers perfused with GCDC, TUDC or a combination of both (each 20 μm for 2 h). GCDC led to a significant increase of lactate dehydrogenase (LDH) into the effluent perfusate, which was prevented by TUDC. GCDC, TUDC and co-perfusion induced distinct gene expression changes. While GCDC upregulated the expression of several pro-inflammatory genes, co-perfusion with TUDC increased the expression of pro-proliferative and anti-apoptotic p53 target genes. In line with this, levels of serine20-phosphorylated p53 and of its target gene p21 were elevated by GCDC in a TUDC-sensitive way. GCDC upregulated the oxidative stress surrogate marker 8OH(d)G and the pro-apoptotic microRNAs miR-15b/16 and these effects were prevented by TUDC. The upregulation of miR-15b and miR-16 in GCDC-perfused livers was accompanied by a downregulation of several potential miR-15b and miR-16 target genes. The present study identified changes in the transcriptome of the rat liver which suggest, that TUDC is hepatoprotective by counteracting GCDC-induced gene expression changes.

Risk factor analysis of insufficient fluid intake among urban adults in Wuxi, China: a classification and regression tree analysis

Background

Dehydration due to insufficient fluid intake (IFI) is detrimental to health. This cross-sectional study aimed to assess the fluid intake of urban adults in Wuxi, China, and to identify potential risk factors contributing to IFI.

Methods

Adults were selected from the urban area of Wuxi, China, using a multiple-stage random sampling method. The fluid intake information was obtained with a 24-h self-reported diary over seven consecutive days in both summer and winter of 2015. A classification and regression tree (CART) analysis was conducted to detect the potential risk factors associated with IFI. CART is a machine-learning algorithm that portions the data into subsets by threshold.

Results

A total of 584 adults aged 18–87 years were included. The results showed that the median (P25–P75) values of daily fluid intake of the participants were 1100 (800–1550) mL in summer and 1000 (750–1300) mL in winter. Women had a higher prevalence of IFI than men in both summer (odds ratio (OR) = 2.683, 95% confidence interval (CI): 1.830–3.934) and winter (OR = 2.636, 95% CI: 1.677–4.142). The results of CART analysis showed that, in summer, BMI < 25 kg/m² (probability: 64.2%) and age < 64 years (probability: 67.4%) were main risk factors of IFI for men, and BMI < 29 kg/m² (probability: 81.6%) and living in C Community (probability: 86.7%) were main risk factors for women. In winter, age < 40 years (probability: 81.8%) and BMI < 20 kg/m² (probability: 94.5%) were identified as main risk factors of IFI for men and women, respectively.

Conclusions

Most of the participants living in the study site had IFI. The fluid consumption varied by gender, age, location, and BMI. The findings could be useful for the implementation and optimization of intervention programs by identifying the individuals who may at greater risk of dehydration.

Water turnover among human populations: Effects of environment and lifestyle

OBJECTIVES

To discuss the environmental and lifestyle determinants of water balance in humans and identify the gaps in current research regarding water use across populations.

METHODS

We investigated intraspecific variation in water turnover by comparing data derived from a large number of human populations measured using either dietary survey or isotope tracking. We also used published data from a broad sample of mammalian species to identify the interspecific relationship between body mass and water turnover.

RESULTS

Water facilitates nearly all physiological tasks and water turnover is strongly related to body size among mammals (r2=0.90). Within humans, however, the effect of body size is small. Instead, water intake and turnover vary with lifestyle and environmental conditions. Notably, despite living physically active lives in conditions that should increase water demands, the available measures of water intake and turnover among small-scale farming and pastoralist communities are broadly similar to those in less active, industrialized populations.

CONCLUSIONS

More work is required to better understand the environmental, behavioral, and cultural determinants of water turnover in humans living across a variety of ecosystems and lifestyles. The results of such work are made more vital by the climate crisis, which threatens the water security of millions around the globe.

The Na/Ca Exchange as a Target for Antitumor Effect of 4Hz Pulsing Magnetic Field

The correlation between cell hydration and proliferation is one of the controversial subjects in the present cancer research because the detailed mechanism(s) of correlation between these two cell parameters are not evaluated yet. The fact that magnetic fields have antitumor effects and our previous data that the effect of 4 Hz pulsing magnetic field (PMF) is realized by the activation of Cyclic guanosine monophosphate (cGMP)-dependent Na/Ca exchange allow us to suggest that through the study of PMF effects on cell hydration and proliferation in soft tissues of sarcoma-180 tumor-carrying mice compared with those of healthy ones will be possible to evaluate the character of correlation between cell hydration and proliferation in norm and pathology. The daily 30-min PMF (0.2 mT) exposed on tumor-carrying mice has lifetime prolongation, time-dependent depression of tumor growth, decrease of thermal threshold, and lactate concentration in blood. In the initial (6 days) period tumorigenesis PMF leads to dehydration in spleen cells, which is accompanied by the activation of cell proliferation, while in late periods of tumorigenesis it leads to cell hydration accompanied with proliferation. We are suggesting that PMF-induced overhydration and the increase of cell proliferation in cancer tissue as a consequence of high [Ca]i-induced activation of Ca-calmoduline-NO-cGMP pathway leads to the activation of FNa/Ca exchange, while its antitumor effect expressed in initial period of tumorigenesis is due to the activation of cGMP-dependent FNa/Ca, where because of low [Ca]i, it brings to cell dehydration as a result of reactivation of Na/K pump.

Afternoon urine osmolality is equivalent to 24 h for hydration assessment in healthy children

BACKGROUND/OBJECTIVES

While daily hydration is best assessed in 24-h urine sample, spot sample is often used by health care professionals and researchers due to its practicality. However, urine output is subject to circadian variation, with urine being more concentrated in the morning. It has been demonstrated that afternoon spot urine samples are most likely to provide equivalent urine concentration to 24-h urine samples in adults. The aim of the present study was to examine whether urine osmolality (UOsm) assessed from a spot urine sample in specific time-windows was equivalent to 24-h UOsm in free-living healthy children.

SUBJECTS/METHODS

Among 541 healthy children (age: 3-13 years, female: 45%, 77% non-Hispanic white, BMI:17.7 ± 4.0 kg m^-2), UOsm at specific time-windows [morning (0600-1159), early afternoon (1200-1559), late afternoon (1600-1959), evening (2000-2359), overnight (2400-0559), and first morning] was compared with UOsm from the corresponding pooled 24-h urine sample using an equivalence test.

RESULTS

Late afternoon (1600-1959) spot urine sample UOsm value was equivalent to the 24-h UOsm value in children (P < 0.05; mean difference: 62 mmol kg^-1; 95% CI: 45-78 mmol kg^-1). The overall diagnostic ability of urine osmolality assessed at late afternoon (1600-1959) to diagnose elevated urine osmolality on the 24-h sample was good for both cutoffs of 800 mmol kg^-1 [area under the curve (AUC): 87.4%; sensitivity: 72.6%; specificity: 90.5%; threshold: 814 mmol kg^-1] and 500 mmol kg^-1 (AUC: 83.5%; sensitivity: 75.0%; specificity: 80.0%; threshold: 633 mmol kg^-1).

CONCLUSION

These data suggest that in free-living healthy children, 24-h urine concentration may be approximated from a late afternoon spot urine sample. This data will have practical implication for health care professionals and researchers.

Metabolism in Acute-On-Chronic Liver Failure: The Solution More than the Problem

Chronic inflammatory liver disease with an acute deterioration of liver function is named acute-on-chronic inflammation and could be regulated by the metabolic impairments related to the liver dysfunction. In this way, the experimental cholestasis model is excellent for studying metabolism in both types of inflammatory responses. Along the evolution of this model, the rats develop biliary fibrosis and an acute-on-chronic decompensation. The acute decompensation of the liver disease is associated with encephalopathy, ascites, acute renal failure, an acute phase response and a splanchnic increase of pro- and anti-inflammatory cytokines. This multiorgan inflammatory dysfunction is mainly associated with a splanchnic and systemic metabolic switch with dedifferentiation of the epithelial, endothelial and mesothelial splanchnic barriers. Furthermore, a splanchnic infiltration by mast cells occurs, which suggests that these cells could carry out a compensatory metabolic role, especially through the modulation of hepatic and extrahepatic mitochondrial-peroxisome crosstalk. For this reason, we propose the hypothesis that mastocytosis in the acute-on-chronic hepatic insufficiency could represent the development of a survival metabolic mechanisms that mitigates the noxious effect of the hepatic functional deficit. A better understanding the pathophysiological response of the mast cells in liver insufficiency and portal hypertension would help to find new pathways for decreasing the high morbidity and mortality rate of these patients.

The Role of Water Homeostasis in Muscle Function and Frailty: A Review

Water, the main component of the body, is distributed in the extracellular and intracellular compartments. Water exchange between these compartments is mainly governed by osmotic pressure. Extracellular water osmolarity must remain within very narrow limits to be compatible with life. Older adults lose the thirst sensation and the ability to concentrate urine, and this favours increased extracellular osmolarity (hyperosmotic stress). This situation, in turn, leads to cell dehydration, which has severe consequences for the intracellular protein structure and function and, ultimately, results in cell damage. Moreover, the fact that water determines cell volume may act as a metabolic signal, with cell swelling acting as an anabolic signal and cell shrinkage acting as a catabolic signal. Ageing also leads to a progressive loss in muscle mass and strength. Muscle strength is the main determinant of functional capacity, and, in elderly people, depends more on muscle quality than on muscle quantity (or muscle mass). Intracellular water content in lean mass has been related to muscle strength, functional capacity, and frailty risk, and has been proposed as an indicator of muscle quality and cell hydration. This review aims to assess the role of hyperosmotic stress and cell dehydration on muscle function and frailty.

Sudden unexpected death in Parkinson’s disease: why is drinking water important?

Parkinson’s disease (PD) is one of the most common age-related neurodegenerative disorders. Several studies over the last few years have shown that PD is accompanied by high rates of premature death compared with healthy controls. Death in PD patients is usually caused by determinant factors such as pneumonia, and cerebrovascular and cardiovascular diseases. During recent years it has emerged that dehydration may also contribute to mortality in PD. Interestingly, it has been documented that a substantial proportion of patients with PD die suddenly (known as sudden and unexpected death in PD). In this article, we focus on the magnitude of the problem of sudden and unexpected death in PD, with special reference to the daily water consumption of PD patients.

Blood flow restriction augments the skeletal muscle response during very low-load resistance exercise to volitional failure

The purpose of this study was to compare the acute muscular response with resistance exercise between the following conditions [labeled (% one-repetition maximum/% arterial occlusion pressure)]: high-load (70/0), very low-load (15/0), very low-load with moderate (15/40), and high (15/80) blood flow restriction pressures. Twenty-three participants completed four sets of unilateral knee extension to failure (up to 90 repetitions) with each condition, one condition per leg, each day. Muscle thickness and maximal voluntary contraction (MVC) were measured before (Pre), immediately after (Post-0), and 15 min after (Post-15) exercise and electromyography (EMG) amplitude during exercise. Pre to Post-0 muscle thickness changes in cm [95% CI] were greater with 15/40 [0.57 (0.41, 0.73)] and 15/80 [0.49 (0.35, 0.62)] compared to 70/0 [0.33 (0.25, 0.40)]. Pre to Post-0 MVC changes in Nm [95% CI] were higher with 15/40 [-127.0 (-162.1, -91.9)] and 15/80 [-133.6 (-162.8, -104.4)] compared to 70/0 [-48.4 (-70.1, -26.6)] and 15/0 [-98.4 (-121.9, -74.9)], which were also different. Over the first three repetitions, EMG increased across sets, whereas in the last three repetitions it did not. EMG was also different between conditions and was generally greater during 70/0. Repetitions decreased across sets reaching the lowest for 70/0, and for very low loads decreased with increased pressure. In trained participants exercising to failure, lower load and the application of restriction pressure augment changes in muscle thickness and torque. The EMG amplitude was augmented by load. Training studies should compare these conditions, as the results herein suggest some muscular adaptations may differ.

Hydration, Arginine Vasopressin, and Glucoregulatory Health in Humans: A Critical Perspective

Glucoregulatory diseases, such as type 2 diabetes are currently a key public health priority. Public health messages have started to include the addition of water in their dietary guidelines. Such guidelines however are not based on causal evidence pertaining to the health effects of increased water intake, but rather more heavily based upon non-causal or mechanistic data. One line of thinking linking fluid intake and health is that hypohydration induces elevated blood concentrations of arginine vasopressin (AVP). Research in the 1970s and 1980s implicated AVP in glucoregulation, supported by observational evidence. This important area of research subsequently appeared to stop until the 21st century during which interest in hypertonic saline infusion studies, animal AVP receptor knockout models, dietary and genetic associations, and human interventions manipulating hydration status have resurged. This narrative review briefly describes and critically evaluates the usefulness of the current AVP-glucoregulatory research. We offer suggestions on how to test the independent glucoregulatory effects of body water changes compared to elevated circulating AVP concentrations, such as investigating hydration manipulations using 3,4-Methylenedioxymethamphetamine. Whilst much research is still needed before making firm conclusions, the current evidence suggests that although AVP may be partially implicated in glucoregulation, more ecologically valid models using human participants suggests this effect might be independent of the hydration status. The key implication of this hypothesis if confirmed in future research is that manipulating the hydration status to reduce circulating AVP concentrations may not be an effective method to improve glucoregulatory health.