Assessment of EN-RAGE, sRAGE, and its isoforms: cRAGE, esRAGE in obese patients treated by moderate caloric restriction combined with physical activity conducted in hospital condition.

BACKGROUND: AGEs, their receptor (RAGE), and the extracellular newly identified receptor for AGEs product-binding protein (EN-RAGE) are implicated in the pathogenesis of inflammation. AIM: We analyzed serum EN-RAGE, soluble RAGE (sRAGE), and their isoforms: endogenous secretory - esRAGE and cleaved - cRAGE concentrations in lean controls (n = 74) and in patients with obesity (n = 71) treated for three weeks with moderate calorie restriction (CR) combined with physical activity in a hospital condition. METHODS: Using the ELISA method, serum sRAGE, esRAGE, and EN-RAGE were measured before and after CR. RESULTS: The serum level of sRAGE and esRAGE in patients with obesity was lower than that in non-obese individuals, contrary to cRAGE. EN-RAGE concentration was about three times higher in obese patients. Gradually, a rise in BMI resulted in sRAGE, esRAGE reduction, and EN-RAGE increase. The sRAGE concentration was sex-dependent, indicating a higher value in lean men. A moderate negative correlation was observed between BMI and all RAGE isoforms, whereas EN-RAGE displays a positive correlation. CR resulted in an expected decrease in anthropometric, metabolic, and proinflammatory parameters and EN-RAGE, but no RAGE isoforms. The ratio EN-RAGE/sRAGE was higher in obese humans than in control and was not modified by CR. CONCLUSION: Obesity decreases sRAGE and esRAGE and increases EN-RAGE concentration. Moderate CR and physical activity by decreasing inflammation reduces EN-RAGE but is insufficient to increase sRAGE and esRAGE to the extent observed in lean patients. EN-RAGE instead of sRAGE could be helpful to indicate a better outcome of moderate dietary intervention in obese subjects.

Comparison of chronotype and learning motivation in medical university students.

BACKGROUND: People differ in their preferred time for intellectual activities. Morningness-eveningness preferences describe the preferred time for performing daily activities and are determined by chronotype. Chronotype reflects circadian preference in humans and is divided into morning, intermediate, and evening types. Learning motivation is a key predictor of student success and may influence learning and study, academic performance, intention to continue medical research, and well-being. Helping students develop learning motivation may improve their educational achievement and health. There are opposing studies regarding chronotype and academic achievement. We hypothesized that chronotype affects the learning motivation of medical school students. METHODS: We used the reduced Morningness-Eveningness Questionnaire (rMEQ), and the Motivated Strategies for Learning Questionnaire (MSLQ) for Russian, Polish, Japanese, and Australian students in the first and second years of medical university. A total of 540 medical students answered the questionnaires. The MSLQ contains six subscales: intrinsic goal orientation, extrinsic goal orientation, self-efficacy for learning and performance, control of learning beliefs, task value, and test anxiety. RESULTS: The rMEQ was used to classify the students into three types, which were morning (26.7%), intermediate (60.5%), or evening chronotypes (12.7%) based on their scores. The learning motivation scores for the intrinsic and extrinsic goal orientations, task value, and self-efficacy were lower in evening chronotypes. CONCLUSIONS: Our findings suggest that the evening chronotype had a lower learning motivation than the morning chronotype. Evening-oriented students may need a more flexible schedule, and a shift of the most important courses in the university to the afternoon may help them to attain higher motivation for learning medicine.

Seasonal differences in clock gene expression levels in buccal epithelial cells of obese men: a pilot study.

Various biological processes show seasonal variations in humans, including important metabolic pathways. Seasonal changes in gene expression may affect annual differences in human immunity. We hypothesized that seasonal changes occur in clock gene expression levels that are associated with body mass index. Six non-obese men and five obese men participated in summer and winter. Two milliliters of saliva were collected, and total RNA was isolated from buccal epithelial cells in saliva. The clock gene expression levels of CLOCK, BMAL1, PER1, CRY2, REV-ERB-α, and REV-ERB-ß were examined by real-time PCR. Blood samples were measured HbA1c, glucose, insulin, adiponectin, IL-6, and TNF-α. Participants were asked about their sleeping hours and seasonal pattern. In the present study, CLOCK, BMAL1, and REV-ERB-ß gene expression levels were significantly lower in winter than in summer; BMAL1 expression level was significantly lower in obese men than in non-obese. Concentrations of adiponectin and insulin were significantly different between obese and non-obese. No significant seasonal effects were observed in HbA1c, glucose, insulin, adiponectin, IL-6, or TNF-α concentrations. Sleep duration did not significantly differ between summer and winter. The short photoperiod during winter might contribute to seasonal alterations in the expression of clock genes in men. In the present results, revealed seasonal differences in clock gene expression levels might be associated with obesity. These results also showed the potential for measuring clock gene expression in a non-invasive manner using saliva samples.

Amaranth (Amaranthus cruentus L.) and canola (Brassica napus L.) oil impact on the oxidative metabolism of neutrophils in the obese patients.

CONTEXT: Amaranth and canola oils have been used traditionally. Amaranth has been identified as being of interest because of its outstanding nutritive value. Amaranth oil is a rich source of highly unsaturated fats and so could be a valuable dietary alternative for individuals affected with obesity. Reactive oxygen species (ROS) are postulated to be involved in systemic inflammation and oxidative stress. Activated polymorphonuclear neutrophils (PMNs) generate high amounts of reactive oxygen species. OBJECTIVE: Our study investigates the impact of amaranth and canola oils supplementation on oxidative metabolism in patients with obesity. We hypothesized that, due to its lipid-lowering and antioxidant properties, amaranth and canola oil would protect against oxidative stress. MATERIALS AND METHODS: We tested 19 obese patients [body mass index (BMI) = 41.1 ± 7.8 kg/m2, (mean ± SD)]. The protocol consisted of two stages: a run-in phase of 2 weeks and an experimental stage - canola or amaranth oil supplementation (20 mL/d) with calorie restriction diet for 3 weeks. The neutrophil oxidative burst was expressed by fluorescence intensity (IF). RESULTS: The oxidative burst had increased significantly at the end of treatment in both groups IF: (21.4 ± 11.15 vs. 35.9 ± 20.3; mean ± SD) p < 0.05. The levels of IF were significantly higher in neutrophils of patients who received canola oil (41.05 ± 25.3) compared to those who received amaranth oil (28.4 ± 11.8) p < 0.05. CONCLUSIONS: Canola oil exerts possible effects on oxidative burst activity in neutrophils in vivo conditions.

Contribution of daily and seasonal biorhythms to obesity in humans.

While the significance of obesity as a serious health problem is well recognized, little is known about whether and how biometerological factors and biorhythms causally contribute to obesity. Obesity is often associated with altered seasonal and daily rhythmicity in food intake, metabolism and adipose tissue function. Environmental stimuli affect both seasonal and daily rhythms, and the latter are under additional control of internal molecular oscillators, or body clocks. Modifications of clock genes in animals and changes to normal daily rhythms in humans (as in shift work and sleep deprivation) result in metabolic dysregulation that favours weight gain. Here, we briefly review the potential links between biorhythms and obesity in humans.

Age-related limitations of interleukin-6 in predicting early mortality in acute ST-elevation myocardial infarction.

Interleukin-6 (IL-6) is an inflammatory cytokine whose levels increase significantly during myocardial infarction (MI). It has been hypothesised that the concentrations of IL-6 at admission may be useful in prognosticating long-term outcomes. It is unclear, however, whether IL-6 could improve the prognosis of early mortality in MI. We have compared serum IL-6 levels and analysed the disease course in 158 patients with ST-elevation MI (STEMI) who either survived (n = 148) or died (n = 10) within 30 days following the admission. Patients were treated in a single university centre with primary percutaneous coronary intervention (PCI). The non-survivors (6.3%) displayed most of typical risk factors for poor outcome. In addition they had significantly higher concentrations of IL-6 at hospital admission (median values 8.5 vs. 2.0 pg/ml; p = 0.038). However, they were also significantly older than the survivors (median values 72 vs. 57 years; p = 0.0001). IL-6 levels are known to increase with age and we could confirm a significant correlation between patients' calendar age and circulating IL-6 (p = 0.009). Regression analysis revealed that IL-6 concentrations were significantly affected by patients' age but they did not independently relate to patients' outcome. Such results indicate that circulating IL-6 at admission may be of limited value in predicting early mortality in STEMI. It is important to recognize that, because of the small group of patients who died (N = 10), the results must be interpreted with caution. Therefore, we stress that these results should be viewed as preliminary and further validated in a larger set of patients.

Seasonal Influence on Salivary Myeloperoxidase Diurnal Variations in Young Healthy Subjects: A Preliminary Study.

BACKGROUND: The interaction between oxidative status markers and biological rhythms is considered particularly important in the pathogenesis of many diseases and more effective therapies. We aimed to determine if the salivary secretion of myeloperoxidase exhibits diurnal variations, and if the potential daily variability differs seasonally. METHODS: The study was performed in Poznan, Poland (52,25°N, 16,58°E) in 10 healthy male volunteers (age median 23.5 years). Whole mixed unstimulated saliva was collected in summer (August) and winter (December) during 36 h at 2-h intervals starting at 6 a.m. on Saturday and ending at 6 p.m. on Sunday, in the domestic setting. The samples were analysed for myeloperoxidase (MPO) and cortisol by immunoassays. The presence of the circadian rhythm of cortisol secretion in saliva confirmed the rhythmicity of the volunteers. RESULTS: For salivary MPO, significantly higher concentrations compared to midnight and noon were observed for 4 a.m. in both summer and winter. Using the cosinor analysis, the variations in salivary MPO levels showed a moderate fit for the 12-h period rhythm (acrophases: in summer 05:37/17:37, in winter 06:16/18:16), without significant differences in the rhythm parameters in summer and winter. However, higher self-reported Global Seasonal Score (which may predispose to seasonal affective disorder) was associated with significantly stronger relative amplitude (RS = 0.811) in winter season only. CONCLUSIONS: In conclusion, our findings suggest the possible ultradian rhythm for MPO in saliva, with two peaks during the day, regardless of the season.

Attenuated thermoregulatory responses with increased plasma osmolality in obese subjects during two seasons.

Obese subjects may be more vulnerable to injury from heat stress, and appear to be less efficient at thermoregulation. Sweat rate, tympanic temperature and osmolality in obese subjects were investigated in Japan during two seasons. The purpose of this study was to examine the relationship between obesity, thermoregulatory response and season. Five obese (BMI, 32.0 ± 4.9 kg/m²) and five non-obese (BMI, 23.2 ± 2.9 kg/m²) men participated in this experiment at latitude 35°10' N and longitude 136°57.9'E. The average atmospheric temperature was 29.1 ± 1.0 °C in summer and 3.3 ± 1.4 °C in winter. Tympanic temperature and sweat rate were measured during leg water immersion at 42 °C for 30 min. Blood samples were analyzed for plasma osmolality. The relationship between tympanic temperature and sweat rate decreased significantly in obese compared to in non-obese subjects in both seasons, there being a lowered sweat rate for any core temperature in obese subjects. Plasma osmolality was significantly higher in obese than in non-obese subjects in both seasons. Thermal sensation increased significantly in non-obese than in obese in winter but not in summer. Our data show that thermoregulatory responses are attenuated in obese subjects compared with controls, suggesting that obese people are at increased risk of heat-related illnesses.

Seasonal differences in melatonin concentrations and heart rates during sleep in obese subjects in Japan.

During the past several decades, obesity has been increasing globally. In Japan, obesity is defined by a BMI of 25 kg/m² or over; 28.6 % of men and 20.6 % of women are obese. Obese people have an increased incidence of developing cardiovascular, renal, and hormonal diseases and sleep disorders. Obese people also have shortened sleep durations. We investigated seasonal differences in melatonin concentrations, heart rates, and heart rate variability during sleep in obese subjects in Japan. Five obese (BMI, 32.0 ± 4.9 kg/m²) and five non-obese (BMI, 23.2 ± 2.9 kg/m²) men participated in this study in the summer and winter. Electrocardiograms were measured continuously overnight in a climatic chamber at 26 °C with a relative humidity of 50 %. Saliva samples for melatonin were collected at 2300 hours, 0200 hours, and 0600 hours. We found that melatonin concentrations during sleep in obese subjects were significantly lower than those in non-obese subjects in the winter. Heart rate during sleep in winter was significantly higher than that in summer in both obese and non-obese subjects. Heart rate variability was not significantly different in the summer and winter in both obese and non-obese subjects. Our results show that decreased nocturnal melatonin concentrations during winter in obese men may be related to higher heart rates, and this may suggest that obese men are at an increased risk of a cardiovascular incident during sleep, especially in the winter.

Effects of living at two ambient temperatures on 24-h blood pressure and neuroendocrine function among obese and non-obese humans: a pilot study.

The effects of environmental temperature on blood pressure and hormones in obese subjects in Japan were compared in two seasons: summer vs winter. Five obese (BMI, 32 ± 5 kg/m(2)) and five non-obese (BMI, 23 ±3 kg/m(2)) men participated in this experiment at latitude 35°10' N and longitude 136°57.9' E. The average environmental temperature was 29 ± 1 °C in summer and 3 ± 1 °C in winter. Blood samples were analyzed for leptin, ghrelin, catecholamines, thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), total cholesterol, triglycerides, insulin and glucose. Blood pressure was measured over the course of 24 h in summer and winter. A Japanese version of the Profile of Mood States (POMS) questionnaire was also administered each season. Systolic and diastolic blood pressures in obese men were significantly higher in winter (lower environmental temperatures) than in summer (higher environmental temperatures). Noradrenaline and dopamine concentrations were also significantly higher at lower environmental temperatures in obese subjects, but ghrelin, TSH, fT3, fT4, insulin and glucose were not significantly different in summer and winter between obese and non-obese subjects. Leptin, total cholesterol and triglyceride concentrations were significantly higher in winter in obese than non-obese men. Results from the POMS questionnaire showed a significant rise in Confusion at lower environmental temperatures (winter) in obese subjects. In this pilot study, increased blood pressure may have been due to increased secretion of noradrenaline in obese men in winter, and the results suggest that blood pressure control in obese men is particularly important in winter.

Diurnal differences in urine flow in healthy young men in a light-controlled environment: a randomized crossover design.

BACKGROUND: Older men often experience nocturnal urination difficulties, reflected by diurnal differences in maximum urine flow (Qmax). Since lower urinary tract symptoms and pathological comorbidities are frequent in older men, it remains unclear whether this diurnal variation is a physiological or pathological phenomenon. Our aim was to quantify the diurnal variability of Qmax in healthy young participants under varying daylight conditions in a stable environment to discern potential underlying causes of nocturnal urination difficulties. METHODS: Twenty-one healthy young men were recruited in a 4-day study utilizing daytime (08:00-18:00) exposure with two light conditions in randomized order: dim (< 50 lx) or bright (~2500 lx). Day 1 was for acclimation, and urine flow was assessed from day 2. The participants urinated ad libitum during day 2 and then at fixed 3-4-h intervals thereafter (days 3-4). Regular urination Qmax at late night (04:00) on day 4 was compared with the nearest voided volume during daytime of day 3 (mDay). RESULTS: Morning Qmax scores (after bed-11:00) on day 2 were significantly lower than evening (17:00-before pre-sleep) in bright conditions and those of daytime (11:00-17:00), evening (17:00-before pre-sleep), and pre-sleep in dim conditions. Pre-sleep Qmax during the ad libitum period was significantly higher in dim than bright conditions. Late-night Qmax values (04:00) on day 4 were significantly lower than Qmax scores of mDay on day 3 in both light conditions. CONCLUSIONS: Healthy young men had a clear diurnal Qmax difference that decreased during late night and morning. In addition, the pre-sleep Qmax values in dim daylight were significantly higher than in bright daylight. Taken together, we conclude that late-night and morning decreases in Qmax are an instinctive physiological phenomenon in humans, and the diurnal difference of Qmax can be influenced by daylight conditions.

Effect of the one-day fasting on cortisol and DHEA daily rhythm regarding sex, chronotype, and age among obese adults.

Introduction: Physiological and biochemical processes in the human body occur in a specific order and show rhythmic variability. Time dependence characterizes the secretion of cortisol and dehydroepiandrosterone (DHEA). One-day fasting implies alternating fasting days and eating days. The study aimed to determine how 24-h fasting affects the daily rhythm of cortisol and DHEA levels in obese people while taking into account gender and chronotype. Methods: Forty-nine obese patients (BMI 32.2-67.1 kg/m2; 25 women and 24 men) underwent a 3-week hospital-controlled calorie restriction diet to reduce body weight. During hospitalization, patients fasted for 1 day, during which only water could be consumed. Samples of whole mixed unstimulated saliva were collected at 2-3-h intervals over a 64-h period and analyzed for cortisol and DHEA by immunoassays. The individual chronotypes were assessed by the morning and evening questionnaire, according to Horne and Östberg. Three components of daily rhythm were evaluated: amplitude, acrophase, and the so-called MESOR. Results: Cortisol rhythm showed differences in amplitude (p = 0.0127) and acrophase (p = 0.0005). The amplitude on the fasting day was 11% higher (p = 0.224) than the day after. The acrophase advanced on the day of fasting, 48 min earlier than the day before (p = 0.0064), and by 39 min to the day after fasting (p = 0.0005). In the rhythm of DHEA, differences were found in the MESOR (p = 0.0381). The MESOR on the fasting day increased. Discussion: Our results obtained during 64 consecutive hours of saliva sampling suggest that one-day fasting may affect three components of cortisol and DHEA daily rhythm. Additionally, no differences were found in the daily rhythm between the morning and evening chronotypes and between females and males. Although aging did not influence daily cortisol rhythm, DHEA amplitude, MESOR, and acrophase changed with age. To the best of our knowledge, this is the first presentation of changes in DHEA rhythm during one-day fasting.

No effects of acclimation to heat on immune and hormonal responses to passive heating in healthy volunteers.

Heat acclimation results in whole body-adaptations that increase heat tolerance, and might also result in changed immune responses. We hypothesized that, after heat acclimation, tumor necrosis factor alpha, interleukin 6 and the lymphocyte count would be altered. Heat acclimation was induced in 6 healthy men by 100 min of heat exposure for 9 days. Heat exposure consisted of (1) 10 min of immersion up to chest-level in water at 42°C and (2) 90 min of passive heating by a warm blanket to maintain tympanic temperature at 37.5°C. The climatic chamber was maintained at 40°C and a relative humidity of 50%. Blood samples were analyzed before and after heat acclimation for natural killer (NK) cell activity, counts of lymphocytes B and T, before and after heat acclimation for peripheral blood morphology, interleukin 6, tumor necrosis factor alpha, and cortisol. A Japanese version of the profile of mood states questionnaire was also administered before and after acclimation. The concentrations of white blood cells, lymphocytes B and T, cortisol, interleukin 6, tumor necrosis factor alpha and NK cell activity showed no significant differences between pre- and post-acclimation, but there was a significantly lower platelet count after acclimation and, with the profile of mood states questionnaire, there was a significant rise in anger after acclimation. It is concluded that heat acclimation by passive heating does not induce alterations in immune or endocrine responses.

Effect of Flaxseed (Linum usitatissimum L.) Supplementation on Vascular Endothelial Cell Morphology and Function in Patients with Dyslipidaemia-A Preliminary Observation.

CONTEXT: Flaxseed has a characteristic fatty acids composition and unique phytonutrient profile that may have health-promoting properties. OBJECTIVE: This study aimed to determine the effects of 10 weeks of supplementation with the flaxseed (28 g/day) on endothelial cells (EC) function, serum lipids and proinflammatory mediators in patients with mild and severe dyslipidaemia. MATERIALS AND METHODS: Eleven lean patients with severe dyslipidaemia treated with apheresis (group 1; 10 weeks treated in four phases: (i) ordinary diet, (ii) ordinary diet + flaxseed, (iii) ordinary diet (wash out), (iv) ordinary diet + placebo) and eleven obese patients with mild dyslipidaemia-not treated with apheresis (group 2; 10 weeks treated in two phases: (i) ordinary diet, (ii) low fat diet + flaxseed). Flaxseed was given blindly. Serum was collected at the end of each phase of the study. ECs were exposed in vitro to the medium supplemented with pooled serum taken from patients from both groups to detect their morphological changes using light and electron microscopy. ECs proliferation was also measured at the end of each study phase. RESULTS: Serum vascular endothelial growth factor was decreased after flaxseed supplementation but only in group 1. ECs proliferation was increased after flaxseed supplementation only in obese patients. ECs exposed to medium supplemented with obese patients' serum revealed the following cellular abnormalities: accumulation of lipid droplets, changes of rough endoplasmic reticulum and mitochondria, and flaxseed did not reverse observed changes. At the same time, flaxseed supplementation decreases total cholesterol in both tested groups, low-density lipoprotein cholesterol in group 1 and triglycerides in group 2. CONCLUSIONS: Our findings support the potential role of flaxseed in treating dyslipidaemia but indicate only a slight impact on endothelial cell function.

Effects of aging on thermoregulatory responses and hormonal changes in humans during the four seasons in Japan.

Physiological functions are impaired in various organs in aged people, as manifest by, e.g., renal and cardiac dysfunction and muscle atrophy. The elderly are also at increased risk of both hypothermia and hyperthermia in extreme temperatures. The majority of those over 65 years old have elevated serum osmolality. Our hypothesis is that the elderly have suppressed osmolality control in different seasons compared to the young. Eight healthy young men and six healthy older men participated in this study. The experiments were performed during spring, summer, autumn and winter in Japan, with average atmospheric temperatures of 15-20°C in spring, 25-30°C in summer, 15-23°C in autumn and 5-10°C in winter. Each subject immersed his lower legs in warm water at 40°C for 30 min. Core (tympanic) temperature and sweat rate at chest were recorded continuously. Blood was taken pre-immersion to measure the concentrations of antidiuretic hormone, serum osmolality, plasma renin activity, angiotensin II, aldosterone, leptin, thyroid stimulating hormone, fT(3) and fT(4). The results suggested that the elderly have suppressed osmolality control compared to the young; osmolality was especially elevated in winter compared to the summer in elderly subjects. Therefore, particularly in the elderly, balancing fluid by drinking water should be encouraged to maintain euhydration status in winter.

Moderate Caloric Restriction Partially Improved Oxidative Stress Markers in Obese Humans.

Oxidative stress and inflammation are implicated in obesity. Therefore, we investigated whether moderate and short-term calorie restriction (CR) reflects a real-life situation, mediates weight loss, and improves oxidative stress markers. We analyzed oxidative stress markers in patients with obesity undergoing moderate CR. Serum oxidative stress markers (myeloperoxidase (MPO), superoxide dismutase (SOD), catalase, total antioxidant status (TAS), and reactive oxygen species (ROS) (generation by endothelial cells in vitro)) were measured in 53 subjects (mean BMI 37.8 ± 5.9 kg/m2) who underwent 8 weeks of CR, which included a reduction of 300-500 kcal/day. MPO was the most CR-sensitive parameter. The mean level of serum MPO in patients with obesity was 20% higher than that in post CR intervention (p < 0.001). SOD increased by 12% after CR (p < 0.05), which was largely due to the improvement in glucose tolerance and the reduction in insulin resistance after CR. Other tested parameters were not modified during the treatment. CR resulted in an expected decrease in body weight (by 5.9 ± 4.6 kg, p < 0.0001) and other anthropometric parameters. Additionally, it was accompanied by a significant change in hsCRP, hsTNF alpha, hsIL-6, leptin (all p < 0.0001), and HOMA-IR (p < 0.05). Cardiovascular and metabolic parameters were also partially improved. Short-term, moderate CR partially improves antioxidant capacity but is enough to substantially change anthropometric parameters in obese patients. Our observations indicate that mimicking real-life situations and low-cost dietary intervention can be successfully implemented in obesity treatment with a simultaneous moderate effect on antioxidant status.

Diurnal rhythms of urine volume and electrolyte excretion in healthy young men under differing intensities of daytime light exposure.

In humans, most renal functions, including urine volume and electrolyte excretions, have a circadian rhythm. Light is a strong circadian entrainment factor and daytime-light exposure is known to affect the circadian rhythm of rectal temperature (RT). The effects of daytime-light exposure on the diurnal rhythm of urinary excretion have yet to be clarified. The aim of this study was to clarify whether and how daytime exposure to bright-light affects urinary excretions. Twenty-one healthy men (21-27 years old) participated in a 4-day study involving daytime (08:00-18:00 h) exposure to two light conditions, Dim (< 50 lx) and Bright (~ 2500 lx), in a random order. During the experiment, RT was measured continuously. Urine samples were collected every 3 ~ 4 h. Compared to the Dim condition, under the Bright condition, the RT nadir time was 45 min earlier (p = 0.017) and sodium (Na), chloride (Cl), and uric acid (UA) excretion and urine volumes were greater (all p < 0.001), from 11:00 h to 13:00 h without a difference in total daily urine volume. The present results suggest that daytime bright light exposure can induce a phase shift advance in urine volume and urinary Na, Cl, and UA excretion rhythms.

No Significant Effect of the Individual Chronotype on the Result of Moderate Calorie Restriction for Obesity-A Pilot Study.

BACKGROUND: Chronotype is the pattern of the circadian rhythm that allows an individual to optimize times of sleep and activity. It has been observed that chronotypes may associate with some conditions and diseases, including obesity. It is not known, however, whether chronotypes determine the effectiveness of weight loss regimens. Therefore, in the present study, we compared the outcomes of a 3-week moderate calorie restriction undertaken by individuals with obesity under the same controlled hospital conditions. METHODS: A total of 131 participants with obesity (median BMI 40.0) were studied. The subjects underwent the same dietary intervention over 3 weeks, with a 30% reduction in daily caloric intake. The individual chronotypes were assessed by the morning and evening questionnaire (MEQ) according to Horne and Östberg. Anthropometric and biochemical parameters were assessed by routine methods. RESULTS: Of all patients examined, 75% had the morning (lark) chronotype and 25% had the evening (owl) chronotype. These patient sub-groups did not differ in terms of demographic, anthropometric and biochemical characteristics at baseline. After 3 weeks of calorie restriction, both groups experienced a similar loss of weight and BMI (Body Mass Index) (3.4 ± 0.38% for larks vs. 4.1 ± 0.47% for owls, p = 0.45), with owls exhibiting a marginally greater loss of body fat (3.1 ± 0.79%) compared with larks (2.6 ± 0.64%), p = 0.02. On the other hand, the larks had a more discernable, but not statistically significant from owls, decrease in glycated haemoglobin and CRP (C Reactive Protein). CONCLUSIONS: The chronotype of individuals with obesity does not have a significant effect on the magnitude of the body weight loss, but there is a tendency observed towards the reduction in body fat content in owls through changing their meal and sleep timing to earlier hours, in response to moderate calorie restriction applied under the same controlled conditions.

Influence of season on plasma antidiuretic hormone, angiotensin II, aldosterone and plasma renin activity in young volunteers.

We investigated seasonal changes in hormonal and thermoregulatory responses. Eight volunteers were subjected to the experiment at four times of the year: around the vernal and autumnal equinoxes, and at the summer and winter solstices at latitude 35 degrees N. Plasma antidiuretic hormone (ADH), angiotensin II (ANG II), aldosterone (ALD) and plasma renin activity (PRA) were analyzed before and after water immersion. Seasonal changes in thermoregulatory responses were assessed by measuring core temperature and sweat rate during immersion of the leg in hot water (at 42 degrees C) for 30 min in a room maintained at 26 degrees C. The concentration of plasma ADH and ALD before water immersion was significantly higher in summer than in other seasons. The concentrations of ANG II and PRA did not show seasonal variations. Changes in tympanic temperature during water immersion showed significant differences between seasons, and were higher in winter than in other seasons. The sweat rate was significantly higher in summer than in other seasons. In summary, ADH and ALD concentrations displayed a seasonal rhythm with marked elevation in summer; this may be a compensative mechanism to prevent dehydration from increased sweat loss during summer due to heat acclimatization.

Leptin and ghrelin levels in humans during physical inactivity induced by head-down bed rest.

INTRODUCTION: The aim of this study was to investigate the consequences of 20 d of physical inactivity using head-down bed rest (HDBR) at -6 degrees on leptin, ghrelin, and counter-regulatory hormone responses. METHODS: Eight male volunteers were subjected to HDBR for 20 d. Variables measured before, during, and after HDBR included plasma cortisol, insulin, glucose, leptin, ghrelin, thyroid stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3). RESULTS: No changes in ghrelin and leptin concentrations were observed during HDBR. Glucose concentration decreased significantly on the 20th day of HDBR compared to the pre-value (day 0) of HDBR (87.6 +/- 2.0 vs. 93 +/- 1.6 mg x dl(-1)). Significant correlation was observed between glucose and leptin concentrations. DISCUSSION: The results provide the first evidence that 20 d of HDBR is not associated with an alteration in ghrelin concentration. Leptin, insulin, and cortisol concentrations did not differ during 20 d of HDBR.