Azumi Hida

Constitutive Expression of Aryl Hydrocarbon Receptor in Keratinocytes Causes Inflammatory Skin Lesions

ABSTRACT Occupational and environmental exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested to provoke inflammatory and/or allergic disorders, including asthma, rhinitis, and dermatitis. The molecular mechanisms of this PAH-mediated inflammation remain to be clarified. Previous studies implied the involvement of PAHs as irritants and allergens, with the reactive oxygen species generated from the oxygenated PAHs believed to be an exacerbating factor. It is also possible that PAHs contribute to the pathogenesis through activation of aryl-hydrocarbon receptor (AhR)-mediated transcription, since PAHs are potent inducers of the AhR. To address this point, we generated transgenic mouse lines expressing the constitutive active form of the AhR in keratinocytes. In these lines of mice, the AhR activity was constitutively enhanced in the absence of ligands, so that any other direct effects of PAHs and their metabolites could be ignored. At birth, these transgenic mice were normal, but severe skin lesions with itching developed postnatally. The skin lesions were accompanied by inflammation and immunological imbalance and resembled typical atopic dermatitis. We demonstrate that constitutive activation of the AhR pathway causes inflammatory skin lesions and suggests a new mechanism for the exacerbation of inflammatory diseases after exposure to occupational and environmental xenobiotics.

Constitutively Active Aryl Hydrocarbon Receptor Expressed Specifically in T-Lineage Cells Causes Thymus Involution and Suppresses the Immunization-Induced Increase in Splenocytes

The aryl hydrocarbon receptor (AhR) is a transcription factor belonging to the basic helix-loop-helix-PER-ARNT-SIM superfamily. Xenobiotics, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, bind the receptor and trigger diverse biological reactions. Thymocyte development and T cell-dependent immune reactions are sensitive targets of AhR-dependent 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity. However, the exact role of the AhR in T cells in animals exposed to exogenous ligands has not been clarified because indirect effects of activated AhR in other cell types cannot be excluded. In this study, we generated transgenic (Tg) mice expressing a constitutively active mutant of AhR under the regulation of a T cell-specific CD2 promoter to examine AhR function in T cells. The mRNAs of the constitutively active mutant of AhR and an AhR-induced gene, CYP1A1, were expressed in the thymus and spleen of the Tg mice. The transgene expression was clearly detected in the thymocytes, CD4, and CD8 T cells, but not in the B cells or thymus stromal cells. These Tg mice had a decreased number of thymocytes and an increased percentage of CD8 single-positive thymocytes, but their splenocytes were much less affected. By contrast, the increase in number of T cells and B cells taking place in the spleen after immunization was significantly suppressed in the Tg mice. These results clearly show that AhR activation in the T-lineage cells is directly involved in thymocyte loss and skewed differentiation. They also indicate that AhR activation in T cells and not in B cells suppresses the immunization-induced increase in both T cells and B cells.

Gene expression of detoxifying enzymes in AhR and Nrf2 compound null mutant mouse

The arylhydrocarbon receptor (AhR) regulates the expression of cytochrome P450 (CYP)-1 gene family members which catalyze xenobiotic Phase I metabolism, while Nrf2 exerts the concerted regulation of Phase II enzyme genes. We generated AhR and Nrf2 compound null mutant mice to examine the integrated function of AhR- and Nrf2-regulated enzymes in detoxification. Furthermore, we used this mouse model, by administering three different classes of chemical inducers, to examine how xenobiotic metabolism may be influenced in the absence of signals transduced by AhR or Nrf2. The compound mutant mice responded only weakly to AhR ligand or Phase II inducer, while they displayed a clear response to phenobarbital, an inducer of the CYP2B family through another, unrelated transcription factor. Here, we report an initial characterization of the AhR-Nrf2 double mutant mice, which may serve as a simplified bioassay system to evaluate xenobiotic toxicity and metabolic biotransformation of various drugs and environmental chemicals.

Association of body mass index with lifestyle and rotating shift work in Japanese female nurses

Higher body mass index (BMI) values have been reported in rotating shift workers compared with regular daytime workers. This study examines the relationship between work schedule and BMI, and considers whether lifestyle habits could explain the relationship.

Diurnal 24-Hour Rhythm in Ambulatory Heart Rate Variability during the Day Shift in Rotating Shift Workers

Circadian variation in cardiac autonomic nervous system activity and behavior during the day shifts of shift workers has not hitherto been clarified. This study examined diurnal 24-h variation in heart rate variability (HRV), sleep-wake cycle, physical activity, and food intake during the day shift in rotating shift workers. The subjects were female nurses and caregivers working at a health care facility (14 day workers and 13 rotating shift workers). Each subject was asked to undergo 24-h electrocardiograph and step count recordings. Coarse graining spectral analysis was used for approximately 10-min segments of HRV (600 beats) to derive the total power (TOT: >0.04 Hz), integrated power in the low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF: >0.15 Hz) ranges, the ratio of HF power to TOT (HF nu), and the ratio of LF power to HF power (LF/HF). Double cosinor analysis was used to obtain 24-h and 12-h period variations in variables of HRV and physical activity. While no difference was found in the acrophases of either period for step counts or in the 12-h period of HRV variables between the groups, the acrophases of the 24-h period for HRV variables were delayed by 1.3 to 5.5 h in rotating shift workers, and their differences in HF power, HF nu, and LF/HF reached a significant level (p < 0.05). On the days of the experiment, retiring time, waking up time, total time in bed, sleep efficiency, and mealtimes and energy intake for each diet did not differ between the groups. These results suggest that there is a possibility of an abnormal phase angle between circadian variation in cardiac autonomic nervous system activity and the sleep-wake cycle during the day shift in shift workers.

Influence of dietary behavior on the circadian rhythm of the autonomic nervous system as assessed by heart rate variability

BACKGROUND Misalignment of circadian systems is detrimental to human health. However, only a few studies have examined the influence of late meals on the human circadian system. The purpose of this study was to investigate whether delayed meals affect circadian rhythm as assessed by heart rate variability (HRV). METHODS Seven healthy men (aged 22.4±0.4years) participated in this study, which involved delaying mealtimes by 5h for two weeks. Prior to this study, the regular mealtimes of participants were at 08:00, 13:00, and 18:00 (Baseline). During the intervention, each meal was provided at 13:00, 18:00 and 23:00 (Late mealtimes). Circadian variation was assessed by HRV based on R-R intervals calculated from a pulse at the rising phase of each spike in the QRS complex in a 24-h electrocardiograph record. The ratio of low frequency (LF) to high frequency (HF) power (LF/HF) and the ratio of HF power to total power (%HF) were calculated using spectral analysis. The phase and amplitude of HRV variables in a 24-h period were mathematically obtained with double cosinor analysis. RESULTS The acrophase and amplitude for LF power, HF power and %HF in a 24-h period were not significantly different between Baseline and Late mealtimes. On the other hand, the acrophase significantly differed between Baseline and Late mealtimes for heart rate (95%CI, 1.1-3.8h), standard deviation of R-R intervals (95%CI, 2.5-4.4h) and LF/HF (95%CI, 1.1-2.3h). CONCLUSIONS Our findings suggest that delayed mealtimes shift the phase of circadian rhythm of the autonomic nervous system.

Effects of Egg White Protein Supplementation on Muscle Strength and Serum Free Amino Acid Concentrations

The aim of this study was to evaluate the effects of egg white protein compared to carbohydrate intake prior to exercise on fat free mass (FFM), one repetition maximum (1RM) muscle strength and blood biochemistry in female athletes. Thirty healthy female collegiate athletes were recruited for this study and matched by sport type, body fat percentage and 1RM leg curl muscle strength. Participants were randomly divided into two groups: protein group (15.0 g egg white protein; 75 kcal) and carbohydrate group (17.5 g maltodextrin, 78 kcal). Supplements were administered daily at the same time in a double-blind manner prior to training during an 8-week period. Measurements were performed before and after the 8-week regimen. The mean dietary energy intake did not change throughout the study period. FFM and 1RM assessments (i.e., leg curl, leg extension, squat, and bench press) increased in both groups. Furthermore, serum urea and serum citrulline levels after the 8-week regimen increased significantly only in the protein group. Our findings indicated that compared to the carbohydrate supplement, the protein supplement was associated with some changes in protein metabolites but not with changes in body composition or muscle strength.

Effect of the photoperiod in modulating the androgenic control of 1-alkyl-2,3-diacylglycerol composition in the Harderian gland of the golden hamster, Mesocricetus auratus

The golden hamster Harderian gland produces a lipid secretion consisting mainly of 1-alkyl-2,3-diacylglycerol. We investigated the composition of alkyl and acyl groups in male and female hamster Harderian alkyldiacylglycerol, in animals kept in long and short photoperiods. Female hamsters in long days have alkyl groups with long saturated straight chains (C18:0 and C20:0) and methyl-branched chains (even and odd chain length iso-branched and odd chain length anteiso-branched chains). Acyl groups in females in long days are mostly long straight chains (C16:0) and methyl-branched chains. In females, short photoperiods led to reductions in the proportions of methyl-branched chains and changes in the proportions of straight chain alkyl and acyl groups; these changes were prevented by pinealectomy. Male hamsters with intact gonads, maintained in long days, had no methyl-branched chain alkyl or acyl groups; saturated straight chains were generally shorter than those of females and the odd chain length saturated C15:0 acyl group was common. Short photoperiods did not significantly alter the composition of male alkyldiacylglycerol. Castrated male hamsters in long days showed a distinctively female phenotype, with long straight chains and methyl-branched alkyl and acyl groups. Castrated males in short days showed a mixture of male and female characteristics: shorter straight chain alkyl and acyl groups, a total absence of methyl-branched alkyl groups, and the presence of methyl-branched acyl groups. These results and those of other studies suggest that testosterone controls the enzymes isovaleryl acyl-CoA dehydrogenase and 2-methyl branched-chain acyl-CoA dehydrogenase; in the absence of these enzymes, the primers for the synthesis of methyl-branched chain fatty acids are produced. Our results indicate that this control is modulated by short photoperiods (perhaps due to reduced prolactin levels). It is also suggested that characteristics of male-type alkyldiacylglycerol are better adapted to conditions of autumn and winter than are those of female-type alkyldiacylglycerol.

Association of eating behaviours with diurnal preference and rotating shift work in Japanese female nurses: a cross-sectional study

Objectives Our study examines differences in eating behaviour between day workers and rotating shift workers, and considers whether diurnal preference could explain the differences. Methods Japanese female nurses were studied (39 day workers and 123 rotating shift workers, aged 21–63 years) using self-administered questionnaires. The questionnaires assessed eating behaviours, diurnal preference and demographic characteristics. The questionnaire in the Guidelines for the management of obesity disease issued by the Japan Society for the Study of Obesity was used to obtain scores for the levels of obesity-related eating behaviours, including cognition of constitution, motivation for eating, eating as a diversion, feeling of satiety, eating style, meal contents and temporal eating patterns. The Japanese version of the Morningness–Eveningness (ME) questionnaire was used to measure self-rated preference for the degree to which people prefer to be active in the morning or the evening (ME). Results The scores for meal contents and temporal eating patterns in rotating shift workers were significantly higher than those in day workers. The ME score of rotating shift workers was significantly lower, indicating greater eveningness/less morningness among rotating shift workers. Multivariate linear regression revealed that the ME score was significantly negatively associated with temporal eating patterns and showed a negative association with the score for meal contents at a trend level, while current work shift was not significantly correlated with the scores. Conclusions These results suggest that eating behaviours for rotating shift workers are associated with a more unbalanced diet and abnormal temporal eating patterns and that the associations may be explained by diurnal preference rather than by rotating shift work.

Validity of a Semi-Quantitative Food Frequency Questionnaire for Collegiate Athletes

BACKGROUND Food frequency questionnaires (FFQs) have been developed and validated for various populations. To our knowledge, however, no FFQ has been validated for young athletes. Here, we investigated whether an FFQ that was developed and validated to estimate dietary intake in middle-aged persons was also valid for estimating that in young athletes. METHODS We applied an FFQ that had been developed for the Japan Public Health Center-based Prospective Cohort Study with modification to the duration of recollection. A total of 156 participants (92 males) completed the FFQ and a 3-day non-consecutive 24-hour dietary recall (24hDR). Validity of the mean estimates was evaluated by calculating the percentage differences between the 24hDR and FFQ. Ranking estimation was validated using Spearmans correlation coefficient (CC), and the degree of miscategorization was determined by joint classification. RESULTS The FFQ underestimated energy intake by approximately 10% for both males and females. For 35 nutrients, the median (range) deattenuated CC was 0.30 (0.10 to 0.57) for males and 0.32 (-0.08 to 0.62) for females. For 19 food groups, the median (range) deattenuated CC was 0.32 (0.17 to 0.72) for males and 0.34 (-0.11 to 0.58) for females. For both nutrient and food group intakes, cross-classification analysis indicated extreme miscategorization rates of 3% to 5%. CONCLUSIONS An FFQ developed and validated for middle-aged persons had comparable validity among young athletes. This FFQ might be useful for assessing habitual dietary intake in collegiate athletes, especially for calcium, vitamin C, vegetables, fruits, and milk and dairy products.