The effect of drinking tea at high altitude on hydration status and mood

The effect of drinking tea on hydration status and mood was studied in nine male and four female members of expeditions based at Mt. Everest base camp at an altitude of 5,345 m. Whilst exposed to altitude-cold diuresis, participants were subjected to a crossover experimental design comprising two 24-h dietary interventions. In the tea condition, hot brewed tea formed a major part of fluid intake, whereas in the no-tea condition tea was excluded from the diet. Subjects were prohibited in both cases from consuming other caffeinated beverages, caffeinated foods, and alcoholic drinks. Mean fluids ingested [mean (SE); tea=3,193 (259) ml versus no tea=3,108 (269) ml] and urine volume (tea=2,686 (276) ml versus no tea=2,625 (342) ml] were similar under both conditions. Statistical analysis found no difference in urine stimulated as a result of the tea intervention (P=0.81). Several markers of hydration status were also taken immediately pre and post each condition, including measures of urine specific gravity, urine electrolyte balance (K⁺, Na⁺), and urine colour. None of these measures indicated a difference in hydration status as a result of the dietary intervention in either the control or tea condition. A difference was, however, found in mood, with subjects reporting reduced fatigue when tea was included in the diet (P=0.005). The study shows therefore that even when drunk at high altitude where fluid balance is stressed, there is no evidence that tea acts as a diuretic when consumed through natural routes of ingestion by regular tea drinkers, but that it does have a positive effect on mood.     

The influence of the initial state of hydration on endocrine responses to exercise in the heat

Summary This study examines the effect of the initial state of hydration on hormone responses to prolonged exercise in the heat. Five subjects at two initial hydration levels (hypohydrated and hyperhydrated) were exposed to a 36°C environment for 3 h of intermittent exercise. During exercise, the subjects were either fluid-deprived, or rehydrated with water or an isotonic electrolyte sucrose solution (ISO). Both the stress hormones, adrenocorticotropic hormone and cortisol, and the main fluid regulatory hormones, aldosterone, renin activity (PRA) and arginine vasopressin (AVP), were measured in blood samples taken every hour. Prior hyperhydration significantly reduced initial AVP, aldosterone and PRA levels. However, except for AVP, which responded to exercise significantly less in previously hyperhydrated subjects (p<0.05), the initial hydration state did not influence the subsequent vascular and hormonal responses when the subjects were fluid-deprived while exercising. Concurrent rehydration, either with water or with ISO, reduced or even abolished the hormonal responses. There were no significant differences according to the initial hydration state, except for PRA responses, which were significantly lower (p<0.01) in previously hyperhydrated subjects who also received water during exercise. These results indicate that prior hydration levels influence only slightly the hormonal responses to prolonged exercise in the heat. Progressive rehydration during exercise, especially when extra electrolytes are given, is more efficient in maintaining plasma volume and osmolarity and in reducing the hormonal responses.     

Electrolyte Medium Effects on Measurements of Palmar Skin Potential

Two experiments with 12 subjects each compared skin potential recordings taken simultaneously with four different electrolytes. These were polyethylene glycol, hydrated agar (at a site presoaked with water), fresh agar (i.e., not presoaked), and Unibase. The glycol controlled epidermal hydration at a minimal level, while presoaking produced a high level of hydration at the hydrated agar site. Fresh agar and Unibase represented normal recording conditions for these two electrolytes which have been recommended as “standard” for electrodermal measurements. This design permitted a comparison of two standard electrolytes with each other and with recordings from hydrated and unhydrated sites. These comparisons were made for both monophasic negative SPRs and positive SPRs and the prestimulus levels associated with each. The results replicated previous studies in showing a large effect of epidermal hydration on skin potential measurements. Recordings with agar and Unibase did not differ significantly. The effects of hydration were interpreted in terms of a reduction in the resistance of the stratum corneum and of alterations in the functioning of the dermal and epidermal membranes as a result of blockage of the sweat gland pore. In the light of this interpretation, it was suggested that both agar and Unibase substantially alter the functioning of the sweat glands under some conditions, and neither may be entirely suitable for skin potential measurements.     

水化对造影剂性肾小管损害的影响

目的观察水化对造影剂性肾小管损害的影响。方法共入选行冠脉造影的患者66例,分为对照组(n=31,平均年龄为71.77±5.89岁)和水化组(n=35,平均年龄为73.29±6.55岁);水化组是在冠脉造影术前、后各增加饮水1L,术后即予静脉滴注林格氏液500ml(100ml/h),而其他与对照组相同。采用散色比浊法测定造影前、后尿α1-微球蛋白(α1-M)及β2-微球蛋白(β2-M);比较冠脉造影前后两组上述指标的变化。结果组间比较,两组造影前α1,β2-M无显著差异;造影后对照组及水化组α1-M分别为(13.33±3.97)mg/L与(8.45±2.00)mg/L;β2-M分别为(0.78±0.17)mg/L与(0.56±0.11)mg/L,对照组α1-M及β2-M均明显升高(P<0.01)。同组比较,对照组造影前后α1-M为(7.32±1.77)mg/L与(13.33±3.97)mg/L,造影后α1-M明显升高(P<0.01);β2-M分别为(0.49±0.09)mg/L与(0.78±0.17)mg/L,造影后也明显升高(P<0.01);水化组造影前后α1-M分别为(7.85±1.45)mg/L及(8.45±2.00)mg/L,β2-M为(0.53±0.11)mg/L及(0.56±0.11)mg/L,均无显著差异(P>0.05)。结论在冠脉造影前后给予适量水化,能预防或减轻造影剂性肾小管损害。     

EFFECTS OF EXERCISE-INDUCED FATIGUE WITH AND WITHOUT HYDRATION ON STATIC POSTURAL CONTROL IN ADULT HUMAN SUBJECTS

Postural instability can be the result of various factors, including fatigue. Although it is well known that exercise-induced fatigue may be responsible for a decrease in performance, its effects on postural control, as well as those of hydration, have been relatively little explored. This study evaluated the effects of fatigue, with and without rehydration, on postural control in 10 healthy subjects who regularly practice sports activities. All subjects were submitted to three types of ergocycle exercises: maximal oxygen uptake (Vo2max) and submaximal exercises in no-hydrated and hydrated conditions at a power corresponding to approximately 60% of the Vo2max of each subject. Static posturographic tests were performed immediately before (control) and after exercises. The postural control performance decreased from the best to the worst: control, hydration, dehydration, and Vo2max. Fast Fourier transformation of the center of foot pressure showed three patterns of amplitude spectral density, with an increase of spectral amplitude for dehydration, more important for Vo2max conditions. Spectral amplitudes for control and hydration conditions were relatively similar. This hierarchy suggests that fatigue mainly alters muscular effectors and sensory inputs, such as proprioception, resulting in poor postural regulation. Moreover, fluid ingestion could be responsible for the preservation of muscular functions and of sensory afferences accurately regulating postural control.     

Hidratación con Ringer Lactato combinado con diclofenaco rectal en la prevención de pancreatitis poscolangiopancreatografía retrógrada endoscópica

ObjectiveDifferent measures are recommended to reduce pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). We conducted a study in patients with ERCP treated with rectal diclofenac or lactated Ringer's solution, or both interventions, to assess whether there is a decrease in the number of cases of post-ERCP pancreatitis.Material and methodsA mixed cohort study involving 1,896 patients from 2009 to 2018. Up to June 2012 without treatment (Group I). Subsequently, 100 mg of rectal diclofenac (Group II). Since 2016, lactated Ringer's solution 200 ml/hour during the procedure and 4 hours after it, in addition to 500 ml over 30 minutes when the pancreas was cannulated (Group III). Since 2017, lactated Ringer's solution plus Diclofenac (Group IV). There were 725 patients in group I, and 530, 227 and 414 patients in groups II, III and IV, respectively. Factors predisposing to post-ERCP pancreatitis and post-ERCP pancreatitis cases that were defined by consensus criteria have been collected.ResultsThere were 65 cases of post-ERCP pancreatitis (3.4%); 2.9%, 3.4%, 3.1% and 4.3% in groups I, II, III and IV, respectively (P = .640). In group I, there was 4.2% of post-ERCP pancreatitis in naïve papillae and 4%, 4.9% and 6.3% in groups II, III and IV, respectively (P = .585). The severity of post-ERCP pancreatitis and adverse effects were similar in all groups. 38.4% were high-risk patients. There were also no differences in post-ERCP pancreatitis in this group (P = .501).ConclusionIn this work, no benefit was obtained with diclofenac plus hydration in reducing the number and severity of cases of post-ERCP pancreatitis nor with the other prophylactic measures.     

Bioelectrical impedance vector analysis evaluates cellularity and hydration in cirrhotic patients

BACKGROUNDMalnutrition in cirrhotic patients is correlated with mortality and a better response to liver transplantation. However, recovery of the nutritional status in these patients is a challenge due to the difficulty in establishing a reliable nutritional diagnosis. The bioelectrical impedance vector analysis (BIVA) method appears as a feasible tool in clinical practice to define the physiological state of cirrhotic patients by assessing hydration and body cellularity.AIMTo evaluate body composition in cirrhotic patients using BIVA.METHODSThis retrospective cross-sectional study was carried out by following cirrhotic outpatients at a hospital in Porto Alegre, Brazil. A tetrapolar bioelectrical impedance analysis device was used to evaluate cellularity and hydration and to perform the BIVA. The BIVA graphic was elaborated by software and for statistical analysis a significance level of 5% (P ≤ 0.05) was considered.RESULTSOne hundred and ninety patients, 61.1% males, with a mean age of 56.6 ± 11.0 years, were evaluated. Of these, 56.3% had Child-Turcotte-Pugh (CTP) A score, and the prevalent etiology was hepatitis C virus (47.4%). The patients were classified according to cellularity and hydration by the quadrants and ellipses of the BIVA method, quadrant 1 (47.9%); quadrant 2 (18.9%); quadrant 3 (14.2%); and quadrant 4 (18.9%). Those classified in quadrant 1 and 2 had a higher phase angle compared to those in quadrants 3 and 4 (P < 0.001). Quadrant 2 patients had a lower average age than the other groups. The association with CTP score showed that patients in quadrant 2 had a higher proportion of CTP A, and those in quadrant 4 had a higher proportion of CTP C (P < 0.052).CONCLUSIONThe BIVA method allows identification of the cellularity and hydration status of cirrhotic patients, and its association with clinical factors determines the disease severity, age and prognostic index.     

Improved synthesis of key intermediate of grayanotoxin III

A concise improved synthesis of the key intermediate for the synthesis of grayanotoxin III was realized in the present study, featuring a tandem reaction of Michael addition-esterification, Mukaiyama hydration and Mukaiyama dehydrogenaiton.     

Polymer hydration and stiffness at biointerfaces and related cellular processes

The direct and indirect (by changing mechanical properties) effects of hydration at interfaces on cellular processes and tissue diseases are reviewed. The essential effect of substrate stiffness on cellular processes was demonstrated in the last decade. The combined effect of surface stiffness and hydration at interfaces has garnered much less attention, though hydration and dehydration play important roles in biological processes. This review focuses on the studies that demonstrate how hydration affects biological processes at interfaces. Elevated sodium and dehydration stimulate inflammatory signaling in endothelial cells and promote atherosclerosis. Various types of implant and blood contacting device coatings with varied surface stiffness and hydration have been reported. Effect of hydration on polymer modulus of elasticity and viscoelasticity was discussed taking into account cells adhesion, migration, proliferation, differentiation on surfaces with various degree of hydration. Future directions of research were considered, including the use of nanotechnology to regulate the hydration degree.