Genetic evidence for involvement of ß2-adrenergic receptor in brown adipose tissue thermogenesis in humans.

BACKGROUND: Sympathetic activation of brown adipose tissue (BAT) thermogenesis can ameliorate obesity and related metabolic abnormalities. However, crucial subtypes of the ß-adrenergic receptor (AR), as well as effects of its genetic variants on functions of BAT, remains unclear in humans. We conducted association analyses of genes encoding ß-ARs and BAT activity in human adults. METHODS: Single nucleotide polymorphisms (SNPs) in ß1-, ß2-, and ß3-AR genes (ADRB1, ADRB2, and ADRB3) were tested for the association with BAT activity under mild cold exposure (19 °C, 2 h) in 399 healthy Japanese adults. BAT activity was measured using fluorodeoxyglucose-positron emission tomography and computed tomography (FDG-PET/CT). To validate the results, we assessed the effects of SNPs in the two independent populations comprising 277 healthy East Asian adults using near-infrared time-resolved spectroscopy (NIRTRS) or infrared thermography (IRT). Effects of SNPs on physiological responses to intensive cold exposure were tested in 42 healthy Japanese adult males using an artificial climate chamber. RESULTS: We found a significant association between a functional SNP (rs1042718) in ADRB2 and BAT activity assessed with FDG-PET/CT (p < 0.001). This SNP also showed an association with cold-induced thermogenesis in the population subset. Furthermore, the association was replicated in the two other independent populations; BAT activity was evaluated by NIRTRS or IRT (p < 0.05). This SNP did not show associations with oxygen consumption and cold-induced thermogenesis under intensive cold exposure, suggesting the irrelevance of shivering thermogenesis. The SNPs of ADRB1 and ADRB3 were not associated with these BAT-related traits. CONCLUSIONS: The present study supports the importance of ß2-AR in the sympathetic regulation of BAT thermogenesis in humans. The present collection of DNA samples is the largest to which information on the donor's BAT activity has been assigned and can serve as a reference for further in-depth understanding of human BAT function.

Productivity and physiological responses during exposure to varying air temperatures and clothing conditions.

This study assessed the effects of clothing and air temperature combinations on workplace productivity and physiological response. Ten male Japanese subjects were exposed to six combinations of clothing (0.3 clo and 0.9 clo) and air temperature (16°C, 26°C, and 36°C) during which cognitive performance (Bourdon and calculation tests), manual motor performance (finger-tapping test), and physiological responses (heart rate, blood pressure, and skin and oral temperatures) were measured. Both cold exposure and lower clothing levels likely increased the Bourdon test performance. Calculation test performance tended to be affected by exposure to cold or neutral temperatures at the beginning of the test. Cold exposure undermined manual motor performance (especially when combined with fewer clothing items) while heat exposure significantly increased heart rate. Both cold exposure and higher clothing level during heat exposure increased blood pressure. Body temperature, particularly mean skin temperature, increased with higher air temperature and was significantly influenced by clothing insulation during cold exposure. These results provide novel evidence for the effects of clothing and air temperature (particularly cold) on human productivity and physiological responses in humans.

Multiorgan contribution to non-shivering and shivering thermogenesis and vascular responses during gradual cold exposure in humans.

PURPOSE: Human brown adipose tissue (BAT) is known to be a significant thermoeffector in non-shivering thermogenesis (NST), albeit with individual variations in the BAT activity. We hypothesized that humans with less BAT would have more contribution from the skeletal muscle (SM) to NST or earlier shivering onset and greater vasoconstriction to compensate for less BAT-mediated thermogenesis. METHODS: Eighteen males participated in this study. Their BAT activity and detectable volume were investigated. A gradual cold exposure was conducted for inducing NST at 18.6 °C and initiating shivering at 11.6 °C. The energy expenditure, electromyograph of the pectoralis major, skin blood flow, and rectal (Tre) and skin temperatures were evaluated. RESULTS: BAT volume significantly correlated with the change in metabolic heat production during mild cold phase relative to baseline (NST; r = 0.562, P < 0.05), but not with shivering initiation phase (NST+ ST). SM mass correlated with baseline metabolic heat production (Mbase; r = 0.839, P < 0.01) but not with NST or NST + ST. A positive correlation was noted between BAT volume and Tre at the end of the 18.6 °C exposure period (r = 0.586, P < 0.05), which positively correlated with shivering onset time (r = 0.553, P < 0.05). The skin blood flow, mean skin temperature, and forearm and finger skin temperature difference at the end of the 18.6 °C exposure period did not correlate with NST or BAT volume. CONCLUSION: BAT volume positively correlated with NST. Notably, lower Tre in individuals with less BAT volume induced earlier shivering onset for offsetting the less NST. Whereas, no correlation between metabolic and vasomotor responses was observed.

DNA methylation alterations of AXIN2 in serrated adenomas and colon carcinomas with microsatellite instability.

BACKGROUND: Recent work led to recognize sessile serrated adenomas (SSA) as precursor to many of the sporadic colorectal cancers with microsatellite instability (MSI). However, comprehensive analyses of DNA methylation in SSA and MSI cancer have not been conducted. METHODS: With an array-based methylation sensitive amplified fragment length polymorphism (MS-AFLP) method we analyzed 8 tubular (TA) and 19 serrated (SSA) adenomas, and 14 carcinomas with (MSI) and 12 without (MSS) microsatellite instability. MS-AFLP array can survey relative differences in methylation between normal and tumor tissues of 9,654 DNA fragments containing all NotI sequences in the human genome. RESULTS: Unsupervised clustering analysis of the genome-wide hypermethylation alterations revealed no major differences between or within these groups of benign and malignant tumors regardless of their location in intergenic, intragenic, promoter, or 3' end regions. Hypomethylation was less frequent in SSAs compared with MSI or MSS carcinomas. Analysis of variance of DNA methylation between these four subgroups identified 56 probes differentially altered. The hierarchical tree of this subset of probes revealed two distinct clusters: Group 1, mostly composed by TAs and MSS cancers with KRAS mutations; and Group 2 with BRAF mutations, which consisted of cancers with MSI and MLH1 methylation (Group 2A), and SSAs without MLH1 methylation (Group 2B). AXIN2, which cooperates with APC and ß-catenin in Wnt signaling, had more methylation alterations in Group 2, and its expression levels negatively correlated with methylation determined by bisulfite sequencing. Within group 2B, low and high AXIN2 expression levels correlated significantly with differences in size (P = 0.01) location (P = 0.05) and crypt architecture (P = 0.01). CONCLUSIONS: Somatic methylation alterations of AXIN2, associated with changes in its expression, stratify SSAs according to some clinico-pathological differences. We conclude that hypermethylation of MLH1, when occurs in an adenoma cell with BRAF oncogenic mutational activation, drives the pathway for MSI cancer by providing the cells with a mutator phenotype. AXIN2 inactivation may contribute to this tumorigenic pathway either by mutator phenotype driven frameshift mutations or by epigenetic deregulation contemporary with the unfolding of the mutator phenotype.

Effects of bathing-induced changes in body temperature on sleep.

BACKGROUND: Passive body heating before sleep is well known to lead to improved sleep. However, the effects of the degree of change in body temperature by bathing on sleep quality are unclear. The present study aimed to clarify the effects on sleep of bathing-induced changes in body temperature. METHODS: Twenty-three healthy males and females in their 20 s to 50 s bathed in their homes 1.5-2 h before bedtime under three bathing conditions: showering only; short bathing in a bathtub; and long bathing in a bathtub. Sublingual and skin temperatures and thermal sensation before and after bathing, sleep indices such as sleep onset latency, time in bed, sleep efficiency, and wake after sleep onset, all of which were evaluated using an actimeter, and subjective evaluations of sleep were compared among conditions. RESULTS: Sublingual temperature just after bathing was significantly higher with long bathing than with other conditions, and the fall in sublingual temperature from after bathing to before sleep was significantly larger with long bathing than with short bathing. Sleep onset latency by actimeter was significantly reduced with long bathing compared to showering. In addition, subjective evaluations of falling asleep and sleep quality were better with long bathing than with showering or short bathing. CONCLUSIONS: In conclusion, bathing conditions that produce a 0.9 °C increase in sublingual temperature appear effective for falling asleep and sleep quality, because core temperature shows a greater drop to before sleep than those producing an increase of about 0.3 °C increase in sublingual temperature.

Endocrine, inflammatory and immune responses and individual differences in acute hypobaric hypoxia in lowlanders.

When lowlanders are exposed to environments inducing hypobaric hypoxia (HH) such as high mountains, hemodynamic changes occur to maintain oxygen levels in the body. However, changes to other physiological functions under such conditions have yet to be clarified. This study investigated changes in endocrine, inflammatory and immune parameters and individual differences during acute HH exposure using a climatic chamber (75 min of exposure to conditions mimicking 3500 m) in healthy lowlanders. Aldosterone and cortisol were significantly decreased and interleukin (IL)-6, IL-8 and white blood cell (WBC) counts were significantly increased after HH. Lower peripheral oxygen saturation (SpO2) was associated with higher IL-6 and WBC counts, and higher IL-8 was associated with higher cortisol. These findings suggest that endocrine, inflammatory and immune responses are evoked even with a short 75-min exposure to HH and individuals with lower SpO2 seemed to show more pronounced responses. Our results provide basic data for understanding the physiological responses and interactions of homeostatic systems during acute HH.

Autonomic thermoregulatory responses and subjective thermal perceptions upon the initiation of thermal behavior among resting humans in hot and humid environment.

BACKGROUND: While thermoregulatory behavior is critical for maintaining homeostasis, our knowledge of behavioral thermoeffectors in humid heat is limited compared to the control of autonomic thermoeffectors. The predictions that the frequency and duration of intensified humid heat events are expected to increase in the coming years underline this shortcoming. Therefore, this study aims to elucidate the activation of autonomic thermoregulatory responses and subjective thermal perceptions upon deciding to initiate thermal behavior in a hot and humid environment. METHODS: Ten young male adults participated in an experimental trial where local cooling was permitted at any time during the behavioral assessment during passive exposure to humid heat. The air temperature and relative humidity were kept at 33[Formula: see text]C and 80[Formula: see text], respectively. Skin temperatures, core body temperature (T[Formula: see text]), and skin blood flow (forearm, upper arm, and upper back) were obtained 120 s preceding thermal behavior. Local sweat rate (forearm and upper arm) and subjective thermal perceptions (neck and whole-body) upon thermal behavior initiation were also recorded. RESULTS: Mean skin temperature ([Formula: see text]) and T[Formula: see text] increased prior to thermal behavior initiation (p [Formula: see text] 0.002; p [Formula: see text] 0.001). An increase in mean body temperature ([Formula: see text]) was also observed (p < 0.001). However, the initiation of thermal behavior is not preceded by an increase in skin blood flow (p [Formula: see text] 0.154) and local sweat rate (p [Formula: see text] 0.169). An increase in thermal discomfort and skin wetness perception was observed (p [Formula: see text] 0.048; p [Formula: see text] 0.048), while thermal sensation did not differ from the baseline (p [Formula: see text] 0.357). CONCLUSION: These findings suggest that when given the opportunity to behaviorally thermoregulate in a hot and humid environment, changes in skin blood flow and sweat rate are not required for thermal behavior to be initiated in resting humans. Moreover, an increase in [Formula: see text] and T[Formula: see text], which appears to cause an increase in thermal discomfort, precedes thermal behavior. In addition, an increase in [Formula: see text] leading up to thermal behavior initiation was observed, suggesting that changes in [Formula: see text] rather than [Formula: see text] and T[Formula: see text] alone mediate thermal behavior in humid heat. Collectively, the results of this study appear to support the hypothesis that the temporal recruitment of autonomic thermoeffectors follows an orderly manner based on their physiological cost.

Upregulation of cathepsin L gene under mild cold conditions in young Japanese male adults.

BACKGROUND: Physiological thermoregulatory systems in humans have been a key factor for adaptation to local environments after their exodus from Africa, particularly, to cold environments outside Africa. Recent studies using high-throughput sequencing have identified various genes responsible for cold adaptation. However, the molecular mechanisms underlying initial thermoregulation in response to acute cold exposure remain unclear. Therefore, we investigated transcriptional profiles of six young Japanese male adults exposed to acute cold stress. METHODS: In a climatic chamber, the air temperature was maintained at 28°C for 65 min and was then gradually decreased to 19°C for 70 min. Saliva samples were obtained from the subjects at 28°C before and after 19°C cold exposure and were used for RNA sequencing. RESULTS: In the cold exposure experiment, expression levels of 14 genes were significantly changed [false discovery rate (FDR) < 0.05] although the degree of transcriptional changes was not high due to experimental conditions or blunted transcriptional reaction in saliva to cold stress. As a result, differential gene expression analyses detected the cathepsin L (CTSL) gene to be significantly upregulated, with FDR < 0.05 and log2 fold change value > 1; thus, this gene was identified as a differentially expressed gene. Given that the cathepsin L protein is related to invasion of the novel coronavirus (SARS-CoV-2), mild cold stress might alter the susceptibility to coronavirus disease-19 in humans. The gene ontology enrichment analysis for 14 genes with FDR < 0.05 suggested that immune-related molecules could be activated by mild cold stress. CONCLUSIONS: The results obtained from this study indicate that CTSL expression levels can be altered by acute mild cold stress.

Cloning and expression of medaka cholesterol side chain cleavage cytochrome P450 during gonadal development.

Cholesterol side chain cleavage cytochrome P450 (P450scc, Cyp11a) is responsible for the first step in steroidogenesis, catalyzing the conversion of cholesterol to prognenolone. To investigate the differentiation of steroid-producing cells and the function of sex steroids during gonadal differentiation in the teleost fish, medaka (Oryzias latipes), we isolated the full length cDNA of medaka P450scc and analyzed the expression pattern of P450scc mRNA during gonadal development using in situ hybridization. At hatching, and just after the initiation of morphological sex differentiation, we did not detect any P450scc expression in both sexes. In male gonads, expression of P450scc was detected in the interstitial somatic cells 15 days after hatching following the formation of the seminiferous tubule precursor, and was maintained in the interstitial somatic cells throughout testicular development. In the female gonad, expression of P450scc was initially detected in interstitial somatic cells 5 days after hatching. Subsequently, the expression of P450scc was continuously detected in the interstitial somatic cells of the developing ovary. This expression pattern of P450scc differed from that of female specific steroidogenic enzyme P450arom. Both P450scc and P450arom expressing cells, only P450scc expressing cells, and only P450arom expressing cells were observed. Our results suggest that expression of steroidogenic enzymes is regulated by various mechanisms during ovarian development.

Patient's appetite is a good indicator for postoperative feeding: a proposal for individualized postoperative feeding after surgery for colon cancer.

BACKGROUND: In modern postoperative management, early and enforced feeding has been implemented. The aim of this study is to determine the feasibility of individualized feeding according to the patient's appetite. METHODS: Patients who underwent elective surgery for colon cancer from January 2007 to December 2008 were studied. Liquid intake was allowed on the day of operation and solid normal meal (1800 Kcal) was served according to the recovery of appetite. RESULTS: Two hundred and nine patients were included. Open and laparoscopic surgeries were performed in 104 and 105 patients, respectively. Solid meal was started by the second postoperative day in 81.3% of patients. Intravenous drip infusion was completed within 1 day of the start of the solid meal in 86.6% of the patients and 182 out of 209 patients (87.1%) did not require drip infusion by the third postoperative day. There were no mortalities and readmission rate was 1.0% (2/209). CONCLUSION: The introduction of feeding according to the recovery of appetite was safe and feasible with no delay in establishing oral intake.

Effects of acute hypobaric hypoxia on thermoregulatory and circulatory responses during cold air exposure.

BACKGROUND: The thermoregulatory responses during simultaneous exposure to hypoxia and cold are not well understood owing to the opposite reactions of vasomotor tone in these two environments. Therefore, the purpose of this study was to investigate the influences of hypobaric hypoxia on various thermoregulatory responses, including skin blood flow (SkBF) during cold exposure. METHODS: Ten subjects participated in two experimental conditions: normobaric normoxia with cold (NC, barometric pressure (PB) = 760 mmHg) and hypobaric hypoxia with cold (HC, PB = 493 mmHg). The air temperature was maintained at 28 °C for 65 min and gradually decreased to 19 °C for both conditions. The total duration of the experiment was 135 min. RESULTS: The saturation of percutaneous oxygen (SpO2) was maintained at 98-99% in NC condition, but decreased to around 84% in HC condition. The rectal and mean skin temperatures showed no significant differences between the conditions; however, the forehead temperature was higher in HC condition than in NC condition. The pulse rate increased in HC condition, and there was a strong negative relationship between SpO2 and pulse rate (r = - 0.860, p = 0.013). SkBF and blood pressure showed no significant differences between the two conditions. CONCLUSION: These results suggest that hypobaric hypoxia during cold exposure did not alter the overall thermoregulatory responses. However, hypobaric hypoxia did affect pulse rate regardless of cold exposure.

Transcriptomic Changes in Young Japanese Males After Exposure to Acute Hypobaric Hypoxia.

After the genomic era, the development of high-throughput sequencing technologies has allowed us to advance our understanding of genetic variants responsible for adaptation to high altitude in humans. However, transcriptomic characteristics associated with phenotypic plasticity conferring tolerance to acute hypobaric hypoxic stress remain unclear. To elucidate the effects of hypobaric hypoxic stress on transcriptional variability, we aimed to describe transcriptomic profiles in response to acute hypobaric hypoxia in humans. In a hypobaric hypoxic chamber, young Japanese males were exposed to a barometric pressure of 493 mmHg (hypobaric hypoxia) for 75 min after resting for 30 min at the pressure of 760 mmHg (normobaric normoxia) at 28°C. Saliva samples of the subjects were collected before and after hypobaric hypoxia exposure, to be used for RNA sequencing. Differential gene expression analysis identified 30 significantly upregulated genes and some of these genes may be involved in biological processes influencing hematological or immunological responses to hypobaric hypoxic stress. We also confirmed the absence of any significant transcriptional fluctuations in the analysis of basal transcriptomic profiles under no-stimulus conditions, suggesting that the 30 genes were actually upregulated by hypobaric hypoxia exposure. In conclusion, our findings showed that the transcriptional profiles of Japanese individuals can be rapidly changed as a result of acute hypobaric hypoxia, and this change may influence the phenotypic plasticity of lowland individuals for acclimatization to a hypobaric hypoxic environment. Therefore, the results obtained in this study shed light on the transcriptional mechanisms underlying high-altitude acclimatization in humans.

Trainee surgeons do not cause more conversions in laparoscopic colorectal surgery if they are well supervised.

INTRODUCTION: This study was designed to look at the conversion rates and morbidity associated with laparoscopic operations performed by trainee surgeons ascending the learning curve when they are well supervised by staff surgeons. METHODS: A review of 204 consecutive cases was performed. We defined experienced staff surgeons as those who have performed more than 300 laparoscopic resection cases. The trainee surgeons had less than 50 cases of experience during the study period. All operations were performed by the experienced staff surgeon or by the trainee surgeon with the staff surgeon as the first assistant and supervisor. RESULTS: A total of 204 laparoscopic resections for colorectal cancer were studied. The dissection was D3 in 73% (n = 149) of cases with a mean lymph node harvest of 19.4 nodes (range 1-56). The staff surgeons performed 90 cases and trainees performed 114 cases. Twenty-one cases (10.3%) required conversion. The overall morbidity rate was 17.6% and perioperative mortality rate was 1.5%. On bivariate analysis, trainee surgeons were not found to be significantly associated with a higher conversion risk. Multivariate analysis revealed that only the factor of T3 and above was an independent predictor of conversion (odds ratio (OR) 4.1; 95% confidence interval (CI) 1.09-15.48). Multivariate analysis of risk factors for morbidity revealed that it was not conversion (OR 2.37; 95% CI, 0.86-6.76) but rectal surgery (OR 4.09; 95% CI 2.04-9.9) that was the independent risk factor of morbidity. CONCLUSIONS: Inexperienced surgeons do not cause more conversions or postoperative morbidity in laparoscopic colorectal surgery if they are well supervised. Conversion is not independently associated with increased postoperative morbidity.

Non-visual effects of diurnal exposure to an artificial skylight, including nocturnal melatonin suppression.

BACKGROUND: Recently, more consideration is being given to the beneficial effects of lighting on the maintenance and promotion of the health and well-being of office occupants in built environments. A new lighting technology using Rayleigh scattering has made it possible to simulate a blue sky. However, to date, no studies have examined the possible beneficial effects of such artificial skylights. The aims of this study were to examine the non-visual effects of artificial skylights and conventional fluorescent lights in a simulated office environment and to clarify the feature effects of the artificial skylights. METHODS: Participants were 10 healthy male adults. Non-visual effects were evaluated based on brain arousal levels (α-wave ratio and contingent negative variation [CNV]), autonomic nervous activity (heart rate variability [HRV]), work performance, and subjective responses during daytime exposure to either an artificial skylight or fluorescent lights, as well as nocturnal melatonin secretion. RESULTS: Subjective evaluations of both room lighting-related "natural" and "attractive" items and the "connected to nature" item were significantly higher with the skylight than with the fluorescent lights. Cortical arousal levels obtained from the early component of the CNV amplitude were significantly lower with the skylight than with the fluorescent lights, whereas α-wave ratio and work performance were similar between the two light sources. The HRV evaluation showed that sympathetic nerve tone was lower and parasympathetic nerve tone was higher, both significantly, for the skylight than for the fluorescent lights during daytime. Nocturnal melatonin secretion was significantly greater before and during light exposure at night under the daytime skylight than under the fluorescent lights. CONCLUSIONS: Our results suggest that artificial skylights have some advantages over conventional fluorescent lights in maintaining ordinary work performance during daytime with less psychological and physiological stress. The findings also suggest that the artificial skylights would enable built environments to maintain long-term comfort and productivity.

Energy cost and lower leg muscle activities during erect bipedal locomotion under hyperoxia.

BACKGROUND: Energy cost of transport per unit distance (CoT) against speed shows U-shaped fashion in walking and linear fashion in running, indicating that there exists a specific walking speed minimizing the CoT, being defined as economical speed (ES). Another specific gait speed is the intersection speed between both fashions, being called energetically optimal transition speed (EOTS). We measured the ES, EOTS, and muscle activities during walking and running at the EOTS under hyperoxia (40% fraction of inspired oxygen) on the level and uphill gradients (+ 5%). METHODS: Oxygen consumption [Formula: see text] and carbon dioxide output [Formula: see text] were measured to calculate the CoT values at eight walking speeds (2.4-7.3 km h-1) and four running speeds (7.3-9.4 km h- 1) in 17 young males. Electromyography was recorded from gastrocnemius medialis, gastrocnemius lateralis (GL), and tibialis anterior (TA) to evaluate muscle activities. Mean power frequency (MPF) was obtained to compare motor unit recruitment patterns between walking and running. RESULTS: [Formula: see text], [Formula: see text], and CoT values were lower under hyperoxia than normoxia at faster walking speeds and any running speeds. A faster ES on the uphill gradient and slower EOTS on both gradients were observed under hyperoxia than normoxia. GL and TA activities became lower when switching from walking to running at the EOTS under both FiO2 conditions on both gradients, so did the MPF in the TA. CONCLUSIONS: ES and EOTS were influenced by reduced metabolic demands induced by hyperoxia. GL and TA activities in association with a lower shift of motor unit recruitment patterns in the TA would be related to the gait selection when walking or running at the EOTS. TRIAL REGISTRATION: UMIN000017690 ( R000020501 ). Registered May 26, 2015, before the first trial.

Less exposure to daily ambient light in winter increases sensitivity of melatonin to light suppression.

This study was carried out to examine the seasonal difference in the magnitude of the suppression of melatonin secretion induced by exposure to light in the late evening. The study was carried out in Akita (39 degrees North, 140 degrees East), in the northern part of Japan, where the duration of sunshine in winter is the shortest. Ten healthy male university students (mean age: 21.9+/-1.2 yrs) volunteered to participate twice in the study in winter (from January to February) and summer (from June to July) 2004. According to Japanese meteorological data, the duration of sunshine in Akita in the winter (50.5 h/month) is approximately one-third of that in summer (159.7 h/month). Beginning one week prior to the start of the experiment, the level of daily ambient light to which each subject was exposed was recorded every minute using a small light sensor that was attached to the subject's wrist. In the first experiment, saliva samples were collected every hour over a period of 24 h in a dark experimental room (<15 lux) to determine peak salivary melatonin concentration. The second experiment was conducted after the first experiment to determine the percentage of melatonin suppression induced by exposure to light. The starting time of exposure to light was set 2 h before the time of peak salivary melatonin concentration detected in the first experiment. The subjects were exposed to light (1000 lux) for 2 h using white fluorescent lamps (4200 K). The percentage of suppression of melatonin by light was calculated on the basis of the melatonin concentration determined before the start of exposure to light. The percentage of suppression of melatonin 2 h after the start of exposure to light was significantly greater in winter (66.6+/-18.4%) than summer (37.2+/-33.2%), p<0.01). The integrated level of daily ambient light from rising time to bedtime in summer was approximately twice that in winter. The results suggest that the increase in suppression of melatonin by light in winter is caused by less exposure to daily ambient light.

[Mutual relationship between prevalence statistics and mortality statistics in Parkinson's disease].

OBJECTIVE: The purpose of this study is to determine whether the statistics from three published reports on Parkinson's disease (PD) are mutually interrelated and to clarify the relationship between the prevalence statistics and mortality statistics of PD. These statistics included data on "number of patients with PD (PD Patients)", "number of patients with PD receiving financial aid for treatment (PD Recipients)" as an indicator showing the prevalence of PD, and "number of deaths from PD (PD Deaths, i.e., mortality)". METHODS: The data on PD Patients, PD Recipients and PD Deaths were cited from "Patient Survey" by Ministry of Health, Labour and Welfare, a report by the Research Committee on Epidemiology of Intractable Diseases and "Vital Statistics of Japan" by Ministry of Health, Labour and Welfare, respectively. The expected PD Patients, PD Recipients and PD Deaths were calculated as products of their respective rates for the entire country and prefecture population, adjusting for a difference in population composition. Observed/expected number ratios (O/E ratio) of PD Patients, PD Recipients and PD Patients were calculated by prefecture. The correlation between the O/E ratios was examined. In addition, the relationships of the O/E ratios with the number of hospitals or physicians per person were examined. RESULTS: There were no significant correlations between the O/E ratios of PD Patients, PD Recipients or PD Deaths. The O/E ratio of PD Recipients significantly correlated with the numbers of hospitals and physicians per person. CONCLUSION: PD Patients and PD Recipients were included in number of people with PD and PD Deaths was derived from people with PD. However, these statistics do not necessarily reflect the prevalence of PD in each prefecture. When using these published statistics as an indicator of the prevalence of PD, it is necessary to clarify the purpose of their use and to comprehend their characteristics.

Relationship between maximum oxygen uptake and peripheral vasoconstriction in a cold environment.

BACKGROUND: Various individual characteristics affect environmental adaptability of a human. The present study evaluates the relationship between physical fitness and peripheral vasoconstriction in a cold environment. METHODS: Seven healthy male students (aged 22.0 years) participated in this study. Cold exposure tests consisted of supine rest for 60 min at 28 °C followed by 90 min at 10 °C. Rectal and skin temperatures at seven sites, oxygen consumption, and the diameter of a finger vein were measured during the experiment. Metabolic heat production, skin heat conductance, and the rate of vasoconstriction were calculated. Individual maximum oxygen consumption, a direct index of aerobic fitness, was measured on the day following the cold exposure test. RESULTS: Decreases in temperature of the hand negatively correlated with the changes in rectal temperature. Maximum oxygen consumption and the rate of vasoconstriction are positively correlated. Furthermore, pairs of the following three factors are also significantly correlated: rate of metabolic heat production, skin heat conductance, and the rate of vasoconstriction. CONCLUSION: The results of this study suggested that the capacity for peripheral vasoconstriction can be improved by physical exercise. Furthermore, when exposed to a cold environment, fitter individuals could maintain metabolic heat production at the resting metabolic level of a thermoneutral condition, as they correspondingly lost less heat.

Risk factors for heatstroke among Japanese forestry workers.

We examined the risk factors for heatstroke among forestry workers in Japan during the summer. We distributed a questionnaire to 124 forestry workers to determine heatstroke symptoms, degree of sweating and hydration, as well as perceived hotness and amount of sunlight at work sites. Forty of the workers (32.3%) reported experiencing heatstroke symptoms. Thirteen and 21 of them reported such symptoms during July and August, respectively. Eleven workers experienced heatstroke at around 14:00; 5 and 4 developed symptoms at around 11:00 and 10:00, respectively. Groups with and without heatstroke symptoms significantly differed in terms of perceived hotness (p<0.05), sunlight (p<0.05), degree of sweating (p<0.01) and frequency of hydration (p<0.05) while working. Heatstroke symptoms developed in 60.6% of workers aged up to 50 yr, but in only 22.0% of those over the age of 51 (p<0.01). Multiple regression analysis selected the following key variables associated with the development of heatstroke symptoms (R(2)=0.236 and p=0.006): frequency of urination, hotness, BMI and years of forestry work (standard coefficients: +0.229, +0.194, +0.280 and -0.162, respectively). The results of the present study showed that one third of forestry workers developed some symptoms of early heatstroke during summer forestry work. Furthermore, the results indicate that a short duration of forestry service was one of the risk factors contributing to the onset of heatstroke, in addition to heat stress, loss of body water and electrolytes, and obesity.