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As temperatures continue to modify due to weather changes, more regions are being exposed to extreme heat and cold. Physiological distress due to low and high temperatures can affect the heart, blood vessels, liver, and especially, the kidneys. Dehydration causes impaired cell function and heat itself triggers cellular stress. The decline in circulating plasma volume by sweat, which stresses the renal and cardiovascular systems, has been related to some molecules that are crucial players in preventing or provoking cellular damage. Hypovolemia and blood redistribution to cutaneous blood vessels reduce perfusion to the kidney triggering the activation of the renin-angiotensin-aldosterone system. In this review, we expose a deeper understanding of the modulation of molecules that interact with other proteins in humans to provide significant findings in the context of extreme heat and cold environments and renal damage reversal. We focus on the molecular changes exerted by temperature and dehydration in the renal system as both parameters are heavily implicated by weather change (e.g., vasopressin-induced fructose uptake, fructogenesis, and hypertension). We also discuss the compensatory mechanisms activated under extreme temperatures that can exert further kidney injury. To finalize, we place special emphasis on the renal mechanisms of protection against temperature extremes, focusing on two important protein groups: heat shock proteins and sirtuins.

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The water deficit in particular, reduces the productivity of vegetable crops. To minimize these harmful effects on agriculture, several agronomic and physiological practices are being studied, such as the use of bacteria and water stress attenuators, such as brassinosteroids. Considering the socioeconomic relevance of corn culture and its sensitivity when exposed to water deficit, the objective of the present study was to evaluate the action of brassinosteroids and azospirillum on nitrogen metabolism in corn plants subjected to water stress conditions. The experiment was carried out in a greenhouse, in a period of 47 days, with corn plants, using the hybrid K9606 VIP3. The design was completely randomized, in a 2x2x3 factorial scheme, with six replications. The first factor corresponds to two water regimes (presence and absence of water deficit). The second corresponds to inoculation via seed of Azospirillum brasiliense and absence of inoculation. And the third corresponds to the application of three concentrations of brassinosteroids (0, 0.3 and 0.6 µM). Were determined Nitrate; nitrate reductase; free ammonium; total soluble aminoacids; soluble proteins; proline; glycine betaine and glutamine synthetase. The lack of water in plants provided a reduction in the protein and nitrate reductase contents, in leaves and roots. For ammonium, plants with water deficit inoculated at a concentration of 0.3 µM, obtained an increase of 7.16 (70.26%) and 13.89 (77.04%) mmol NH4 + .Kg-1. DM (Dry mass) on the leaf and root respectively. The water deficit in the soil provided significant increases in the concentrations of glycine betaine, nitrate, proline and aminoacids, both in the leaves and in the roots of the corn plants. On the other hand, the contents of glutamine synthetase had a reduction in both leaves and roots.

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Silicon (Si) is a beneficial element that can mitigate effects of water stress on photosynthetic metabolism and plant growth. Thus, the aimed was to evaluate the effect of Si in mitigating the stressful effect of water deficit and flooding in Eugenia myrcianthes Nied. seedlings. The seedlings received three silicon doses (0, 2, and 4 mmol) and were subjected to two water regimes (I - continuous irrigation and S - water fluctuation, characterized as water stress obtained by two cycles of water regimes: irrigation suspension and flooding). Each cycle was ended when the seedlings had a photosynthetic rate close to zero (P0) when the stressful irrigation condition was normalized until the photosynthetic rate reached the values of the control seedlings (REC). The evaluations were carried out in five periods: T0 - initial seedling condition; 1st and 2nd P0; and 1st and 2nd REC. The E. myrcianthes seedlings reached P0 at 22 and 50 days under water deficit and flooding, respectively. Water stress caused damage to photochemical activities in photosystem II. E. myrcianthes is a species sensitive to water stress, but capable of adjusting to water fluctuation, and the application of 2 mmol Si contributed to the regulation of gas exchange, photochemical yields, and growth of this species at the deficit and flooding phases. We emphasize that E. myrcianthes seedlings have potential for resilience due to physiological plasticity, regardless of the silicon application.

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Aging is associated a decrease in thirst sensation, which makes old people more susceptible to dehydration. Dehydration produces energy metabolism alterations. Our objective was to determinate the effect of water deprivation (WD) in the lipid metabolism of old male and female rats. Here we show that in the state of WD, aging and sex alters retroperitoneal white adipose tissue (R-WAT) weight of rats, WD old female rats had more lipolysis products than old male rats, a sexual dimorphism in the hormonal response related with metabolism of the adipose tissue of old rats during WD, the expression of P-para mRNA in R-WAT did not present any alteration in animals submitted to WD, the expression of Aqp7 mRNA in R-WAT is altered by WD, age, and sex. Also, WD stimulated an increase in the plasma concentration of oxytocin and the expression of mRNA of the oxytocin receptors in R-WAT.

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The Valparaiso region in Chile was decreed a zone affected by catastrophe in 2019 as a consequence of one of the driest seasons of the last 50 years. In this study, three varieties ('Alfa-INIA', 'California-INIA', and one landrace, 'Local Navidad') of kabuli-type chickpea seeds produced in 2018 (control) and 2019 (climate-related catastrophe, hereafter named water stress) were evaluated for their grain yield. Furthermore, the flavonoid profile of both free and esterified phenolic extracts was determined using liquid chromatography-mass spectrometry, and the concentration of the main flavonoid, biochanin A, was determined using liquid chromatography with diode array detection. The grain yield was decreased by up to 25 times in 2019. The concentration of biochanin A was up to 3.2 times higher in samples from the second season (water stress). This study demonstrates that water stress induces biosynthesis of biochanin A. However, positive changes in the biochanin A concentration are overshadowed by negative changes in the grain yield. Therefore, water stress, which may be worsened by climate change in the upcoming years, may jeopardize both the production of chickpeas and the supply of biochanin A, a bioactive compound that can be used to produce dietary supplements and/or nutraceuticals.

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OBJECTIVE AND DESIGN: The exacerbate inflammatory response contributes to the progressive loss of lung function in cystic fibrosis (CF), a genetic disease that affects the osmotic balance of mucus and mucociliary clearance, resulting in a microenvironment that favors infection and inflammation. The purinergic system, an extracellular signaling pathway characterized by nucleotides, enzymes and receptors, may have a protective role in the disease, through its action in airway surface liquid (ASL) and anti-inflammatory response. MATERIALS AND METHODS: To make up this review, studies covering topics of CF, inflammation, ASL and purinergic system were selected from the main medical databases, such as Pubmed and ScienceDirect. CONCLUSION: We propose several ways to modulate the purinergic system as a potential therapy for CF, like inhibition of P2X7, activation of P2Y2, A2A and A2B receptors and blocking of adenosine deaminase. Among them, we postulate that the most suitable strategy is to block the action of adenosine deaminase, which culminates in the increase of Ado levels that presents anti-inflammatory actions and improves mucociliary clearance. Furthermore, it is possible to maintain the physiological levels of ATP to control the hydration of ASL. These therapies could correct the main mechanisms that contribute to the progression of CF.

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Currently, there is the paradox of low water intake but increased intake of sugar-sweetened beverages (SB) in several populations; those habits are associated with an increased prevalence of metabolic derangements and greater chronic disease mortality. Persistent heat dehydration and increased SB intake stimulate the continued release of vasopressin and overactivation of the polyol-fructokinase pathway, synergizing each other, an effect partially mediated by oxidative stress. The objective of the present study was to evaluate whether water restriction concurrent with SB hydration can cause renal damage by stimulating similar pathways as heat dehydration. Three groups of male Wistar rats (n = 6) were fluid restricted; from 10 am to 12 pm animals could rehydrate with tap water (W), or sweetened beverages, one prepared with 11% of a fructose-glucose combination (SB), or with the noncaloric edulcorant stevia (ST). A normal control group of healthy rats was also studied. The animals were followed for 4 weeks. Markers of dehydration and renal damage were evaluated at the end of the study. Fluid restriction and water hydration mildly increased urine osmolality and induced a 15% fall in CrCl while increased the markers of tubular damage by NAG and KIM-1. Such changes were in association with a mild overexpression of V1a and V2 renal receptors, polyol fructokinase pathway overactivation, and increased renal oxidative stress with reduced expression of antioxidant enzymes. Hydration with SB significantly amplified those alterations, while in stevia hydrated rats, the changes were similar to the ones observed in water hydrated rats. These data suggest that current habits of hydration could be a risk factor in developing kidney damage.

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OBJECTIVE: To evaluate the hydration of obese and non-obese adolescents by vectorial bioimpedance analysis, in addition to verifying the associations between obesity and bioelectrical impedance vectorial analysis (BIVA) parameters. METHODS: A cross-sectional study with adolescents between 14 and 18 years old (n=489, 300 boys and 189 girls). Electric bioimpedance (BIA; Quantum_II, RJL system, Rome, Italy) provided resistance and reactance parameters to calculate phase angle (PA), fat-free mass (FFM) and body fat (%BF). The confidence ellipses were compared, and the construction of the tolerance ellipses allowed individual and qualitative evaluation of the vectors and classification in dehydrated, normohydrated and hyperhydrated. RESULTS: 78 obese and 411 eutrophic adolescents participated. Resistance (p<0.001) and reactance (p<0.001) and their normalization by stature (p<0.001) were reduced in the obese, whereas the PA was higher (p=0.003). %BF was 11.3% higher in obese adolescents. The main vector of the obese, both male (D=1.38; p<0.001) and female (D=1.49; p<0.001), indicated greater hydration. The ellipse of tolerance of the total sample showed that 25 (32.1%) were hyperhydrated and 02 (2.6%) vectors positioned in the sense of dehydration. A total of 17 (53.2%) girls and 16 (34.8%) boys were hyperhydrated. Logistic regression showed an inverse relation of BMI with resistance (p<0.001), reactance (p<0.001) and both normalized by stature. Adolescents with increased PA (p<0.001) were twice as likely to present obesity. CONCLUSIONS: Obese adolescents were hyperhydrated and there was an inverse relationship of BMI with resistance and direct with PA.

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ABSTRACT Objective: To evaluate the hydration of obese and non-obese adolescents by vectorial bioimpedance analysis, in addition to verifying the associations between obesity and bioelectrical impedance vectorial analysis (BIVA) parameters. Methods: A cross-sectional study with adolescents between 14 and 18 years old (n=489, 300 boys and 189 girls). Electric bioimpedance (BIA; Quantum_II, RJL system, Rome, Italy) provided resistance and reactance parameters to calculate phase angle (PA), fat-free mass (FFM) and body fat (%BF). The confidence ellipses were compared, and the construction of the tolerance ellipses allowed individual and qualitative evaluation of the vectors and classification in dehydrated, normohydrated and hyperhydrated. Results: 78 obese and 411 eutrophic adolescents participated. Resistance (p<0.001) and reactance (p<0.001) and their normalization by stature (p<0.001) were reduced in the obese, whereas the PA was higher (p=0.003). %BF was 11.3% higher in obese adolescents. The main vector of the obese, both male (D=1.38; p<0.001) and female (D=1.49; p<0.001), indicated greater hydration. The ellipse of tolerance of the total sample showed that 25 (32.1%) were hyperhydrated and 02 (2.6%) vectors positioned in the sense of dehydration. A total of 17 (53.2%) girls and 16 (34.8%) boys were hyperhydrated. Logistic regression showed an inverse relation of BMI with resistance (p<0.001), reactance (p<0.001) and both normalized by stature. Adolescents with increased PA (p<0.001) were twice as likely to present obesity. Conclusions: Obese adolescents were hyperhydrated and there was an inverse relationship of BMI with resistance and direct with PA.

RESUMO Objetivo: Avaliar a hidratação de adolescentes obesos e não obesos por meio dos gráficos da análise vetorial por bioimpedância (BIVA), além de verificar as associações entre a obesidade e os parâmetros da BIVA. Métodos: Estudo transversal realizado com adolescentes entre 14 e 18 anos (n=489, 300 meninos e 189 meninas). A bioimpedância elétrica (BIA; Quantum_II, RJL system, Roma, Itália) ofereceu os parâmetros de resistência e reactância para calcular o ângulo de fase (AF), a massa livre de gordura (MLG) e a gordura corporal (GC). As elipses de confiança foram comparadas e a construção das elipses de tolerância permitiu a avaliação individual e a qualitativa dos vetores e, ainda, a classificação em desidratados, normohidratados e hiper-hidratados. Resultados: Participaram do estudo 78 adolescentes obesos e 411 eutróficos. A resistência (p<0,001), a reactância (p<0,001) e a normalização desses pela estatura (p<0,001) estavam reduzidas nos obesos, enquanto o AF foi superior (p=0,003). O percentual de gordura corporal (%GC) foi 11,3% maior nos adolescentes obesos. O vetor principal dos obesos, tanto masculino (Distância de Mahalanobis (D)=1,38; p<0,001) quanto feminino (D=1,49; p<0,001), indicou maior hidratação. A elipse de tolerância da amostra total mostrou que 25 adolescentes (32,1%) estavam hiper-hidratados e dois (2,6%) vetores posicionados no sentido de desidratação. Dezessete (53,2%) meninas e 16 (34,8%) meninos estavam hiper-hidratados. A regressão logística mostrou relação inversa do índice de massa corpórea (IMC) com a resistência (p<0,001) e a reactância (p<0,001), ambas normalizadas pela estatura. Os adolescentes com aumento do AF (p<0,001) apresentaram duas vezes mais chances de serem classificados como obesos. Conclusões: Os adolescentes obesos estavam hiper-hidratados e houve relação inversa do IMC com a resistência e direta com o AF.

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Maize hybrids contrasting for drought tolerance differ during the vegetative stage. Drought is the main constraint on maize production in developing nations. Differences during development between genetic materials of maize grown under water restriction suggest that the plant can be improved with a view to its adaptation. In maize, sensitivity to water stress can occur at any stage of its phenological development. However, few studies report its effects on the vegetative phase of the cycle. On this basis, this study was conducted to examine how shoot and root-system indices are expressed in cultivation under water deficit as well as determine which indicators best explain the difference between hybrids in the evaluated water regimes. Commercial seeds of hybrids BR1055 and DKB-390 (drought-tolerant) and BRS1010 (drought-sensitive) were germinated in PVC tubes (1.0 m × 0.1 m) in a randomized complete block design, in a 3 × 2 factorial arrangement. The experiment was developed in a greenhouse where two water regimes were tested: no water stress and with water stress from the VE stage. The soil consisted of quartz sand mixed with a commercial fertilizer. Stem and root traits were evaluated up to the V5 growth stage. Relative chlorophyll content, leaf temperature, stem length, phenology, shoot dry biomass, root length, root dry biomass, root surface area, root volume and D95 were responsive to water deficit. The parameters that allowed the distinction between the hybrids in water the regimes were relative chlorophyll content, leaf temperature, phenology and average root diameter.(AU)

Híbridos de milho contrastantes para tolerância à seca diferem durante o estágio vegetativo. A seca é o principal fator de restrição para a produção de milho nas nações em desenvolvimento. Diferenças durante o desenvolvimento entre materiais genéticos de milho cultivados sob restrição de água sugerem que a planta pode ser melhorada visando a sua adaptação. No milho a sensibilidade ao estresse hídrico pode ocorrer em qualquer estágio do seu desenvolvimento fenológico. Contudo, poucos estudos relatam seus efeitos na fase vegetativa do ciclo. Desse modo, esse estudo teve como objetivos verificar como indicadores de parte aérea e sistema radicular se expressam mediante o cultivo sob déficit de água, bem como verificar quais indicadores melhor explicam a diferença entre híbridos nos regimes hídricos avaliados. Semente comerciais dos híbridos BR1055 e DKB-390 (tolerantes à seca) e BRS1010 (sensível à seca) foram germinadas em tubos de PVC (1,0 m x 0,1m) em delineamento em blocos completos em esquema fatorial 3 x 2. O ensaio foi realizado em casa de vegetação em dois regimes hídricos; sem estresse hídrico e com estresse hídrico a partir do estádio VE. O solo foi constituído de areia de quartzo misturada com um fertilizante comercial. As características do caule e da raiz foram avaliadas até o estádio de crescimento V5. O teor relativo de clorofila, a temperatura foliar, comprimento do caule, fenologia, biomassa seca da parte aérea, comprimento de raiz, biomassa seca de raiz, área de superfície radicular, volume de raiz e D95 foram responsivos ao déficit hídrico. Os parâmetros que permitiram a distinção entre os híbridos nos regimes hídricos foram o teor relativo de clorofila, temperatura foliar, fenologia e diâmetro médio da raiz.(AU)

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