Yukari Kawano

Effects of feeding schedule changes on the circadian phase of the cardiac autonomic nervous system and serum lipid levels

PurposeThe purpose of this study was to investigate whether scheduling meals earlier in the day affects the circadian phase of the cardiac autonomic nervous system as assessed by heart rate variability (HRV) and serum lipid levels.MethodsHealthy men aged 21.4xa0±xa00.5xa0years (nxa0=xa014) with a habit of regularly skipping breakfast participated in this parallel trial involving altered feeding schedules. Participants in the early mealtime group (EM group, nxa0=xa08) were asked to eat three meals at 8:00, 13:00, and 18:00, and the control group (nxa0=xa06) ate at 13:00, 18:00, and 23:00 for 2xa0weeks. On the measurement day before and after intervention, fasting blood samples and 24-h electrocardiograph recordings were collected. Spectral analysis was used for approximate 10-min HRV segments. Low frequency (LF) power, high frequency (HF) power, and the ratio of HF to total power (%HF) were calculated to assess sympathovagal balance. Acrophases of the circadian rhythm of HRV variables were obtained by nonlinear least squares regression.ResultsTriglyceride and total and LDL cholesterol levels were significantly decreased in the EM group when compared with the control group (pxa0=xa00.035, 0.008, and 0.004, respectively). Acrophases for HRV variables were advanced in the EM group and their difference between before and after the intervention in LF power (−3.2xa0±xa01.2xa0h) and %HF (−1.2xa0±xa00.5xa0h) reached significant level, respectively (pxa0<xa00.05).ConclusionsTiming of meals was a key factor in regulating circadian phases of the cardiac autonomic nervous system and lipid metabolism.

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.

Differential response of arcuate proopiomelanocortin- and neuropeptide Y-containing neurons to the lesion produced by gold thioglucose administration.

The effect of gold thioglucose (GTG) administration on neurons containing feeding‐related peptides in the hypothalamic arcuate nucleus was examined in mice. Intraperitoneal GTG injection increased the body weight and produced a hypothalamic lesion that extended from the ventral part of the ventromedial nucleus to the dorsal part of the arcuate nucleus. Neurons containing proopiomelanocortin (POMC) and neuropeptide Y (NPY) present in the dorsal part of the arcuate nucleus were destroyed by GTG. In addition, the peptide‐containing fibers that extended from the remaining arcuate neurons were degenerated at the lesion site. The number of POMC‐containing fibers in the paraventricular nucleus, dorsomedial nucleus, and lateral hypothalamus was found to have decreased significantly when examined at 2 days and 2 weeks after the GTG treatment. In contrast, the number of NPY‐containing fibers in the lateral hypothalamus remained unchanged after the GTG treatment, probably because of the presence of an unaffected NPY‐containing fiber pathway passing through the tuberal region and projecting onto the lateral hypothalamus. The number of NPY‐immunoreactive fibers in the paraventricular and dorsomedial nuclei showed a moderate but significant decrease at 2 days after the GTG treatment, but it recovered to the normal levels 2 weeks later. The NPY‐containing fibers were found to have regenerated across the lesion site 2 weeks later, and this might contribute to the recovery of the NPY‐immunoreactive fibers in these regions. The present results first demonstrate that POMC‐ and NPY‐containing neurons in the arcuate nucleus respond differently to the lesion produced by the GTG treatment. J. Comp. Neurol. 499:120–131, 2006.

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

BACKGROUNDnMisalignment 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).nnnMETHODSnSeven 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.nnnRESULTSnThe 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).nnnCONCLUSIONSnOur 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 a traditional Chinese herbal medicine, Ren-Shen-Yang-Rong-Tang (Japanese name: Ninjin-Youei-To), on oligodendrocyte precursor cells from aged-rat brain.

Understanding of oligodendrocyte precursor cells and their role in the generation of oligodendrocytes in developing and adult rodents has been considered, particularly much less is known about aged-rodent oligodendrocyte precursor cells and their cell lineage. In this present study, we have developed oligodendrocyte cultures from the 30-month-old rat brain and examined whether oligodendrocyte precursor cells can proliferate in vitro. Adult oligodendrocyte precursor cells (O1(-), O4(+)) and oligodendrocytes (O1(+), O4(+)) are present in the cultures of the 30-month-old rat brain. They are also capable of proliferating and differentiating in the cultures. These capabilities increased four- to fivefold, when the aged rats are treated with Ninjin-Youei-To for 3 months in comparison with those of control aged rats. These results suggest that Ninjin-Youei-To has a potential mitotic effect on oligodendrocyte precursor cells in aged-rat brains and may be expected to have a therapeutic effect on brain aging.

Association of dietary variety with body composition and physical function in community-dwelling elderly Japanese

ObjectivesTo examine the associations of dietary variety with body composition and physical function in community-dwelling elderly JapaneseDesignCross-sectional study.SettingCommunity-based.ParticipantsA total of 1184 community-dwelling elderly adults aged 65 and over.MeasurementsDietary variety was assessed with a food frequency questionnaire (maximum, 10 points) that encompassed the 10 main food components of Japanese meals (meat, fish/shellfish, eggs, milk, soybean products, green/yellow vegetables, potatoes, fruit, seaweed, and fats/oils). Body composition was determined by multifrequency bioelectrical impedance analysis. Physical function was assessed by measuring grip strength and usual walking speed. Multiple linear regression analysis was used to examine the associations of dietary variety with body composition and physical function.ResultsAfter adjusting for potential confounders, higher dietary variety scores were independently associated with higher lean mass (β (SE): 0.176 (0.049), p<0.001) and appendicular lean mass (β (SE): 0.114 (0.027), p<0.001) but not with body fat mass. Elders with a higher dietary variety score had greater grip strength and faster usual walking speed (β (SE): 0.204 (0.071), p=0.004, and β (SE): 0.008 (0.003), p=0.012, respectively).ConclusionGreater dietary variety was significantly associated with greater lean mass and better physical function in Japanese elders. The causal relationship warrants investigation in a prospective study.

Dietary variety and decline in lean mass and physical performance in community-dwelling older Japanese: A 4-year follow-up study

ObjectivesTo examine associations of dietary variety with changes in lean mass and physical performance during a 4-year period in an elderly Japanese population. Design: Four-year prospective study.SettingThe Hatoyama Cohort Study and Kusatsu Longitudinal Study, Japan.Participants935 community-dwelling Japanese aged 65 years or older.MeasurementsDietary variety was assessed using a 10-item food frequency questionnaire. Body composition was determined by multifrequency bioelectrical impedance analysis, and physical performance (grip strength and usual gait speed) was measured in surveys at baseline and 4 years later. Longitudinal analysis included only participants who were originally in the upper three quartiles of lean body mass, appendicular lean mass, grip strength, and usual gait speed. The outcome measures were decline in lean body mass, appendicular lean mass, grip strength, and usual gait speed, defined as a decrease to the lowest baseline quartile level at the 4-year follow-up survey. Associations of dietary variety with the outcome measures were examined by logistic regression analysis adjusted for potential confounders.ResultsIn the fully adjusted model, the odds ratios for decline in grip strength and usual gait speed were 0.43 (95% confidence interval, 0.19–0.99) and 0.43 (confidence interval, 0.19–0.99), respectively, for participants in the highest category of dietary variety score as compared with those in the lowest category. Dietary variety was not significantly associated with changes in lean body mass or appendicular lean mass.ConclusionAmong older adults, greater dietary variety may help maintain physical performance, such as grip strength and usual gait speed, but not lean mass.

Relationship Between Dietary Factors and Bodily Iron Status Among Japanese Collegiate Elite Female Rhythmic Gymnasts.

This cross-sectional study explored the prevalence of iron deficiency (ID) and associations between dietary factors and incidence of ID in female rhythmic gymnasts during preseason periods. Participants were 60 elite collegiate rhythmic gymnasts (18.1 ± 0.3 years [M ± SD]) who were recruited every August over the course of 8 years. Participants were divided into 2 groups according to the presence or absence of ID. Presence of ID was defined either by ferritin less than 12 μg/L or percentage of transferrin saturation less than 16%. Anthropometric and hematologic data, as well as dietary intake, which was estimated via a semiquantitative food frequency questionnaire, were compared. ID was noted in 48.3% of participants. No significant group-dependent differences were observed in physical characteristics, red blood cell counts, hemoglobin, hematocrit, haptoglobin, or erythropoietin concentrations. The ID group had a significantly lower total iron-binding capacity; serum-free iron; percentage of transferrin saturation; ferritin; and intake of protein, fat, zinc, vitamin B2, vitamin B6, beans, and eggs but not iron or vitamin C. The recommended dietary allowance for intake of protein, iron, zinc, and various vitamins was not met by 30%, 90%, 70%, and 22%-87% of all participants, respectively. Multiple logistic analysis showed that protein intake was significantly associated with the incidence of ID (odds ratio = 0.814, 95% confidence interval [0.669, 0.990], p = .039). Participants in the preseasons weight-loss periods showed a tendency toward insufficient nutrient intake and were at a high risk for ID, particularly because of lower protein intake.

Individual and environmental factors related to stage of change in exercise behavior: a cross-sectional study of female Japanese undergraduate students.

BACKGROUNDnThe purpose of the current study was to examine the association between the level of exercise behavior and individual and environmental factors related to exercise behavior among female Japanese undergraduate students.nnnMETHODSnThe participants were 2482 female Japanese undergraduate students. Participants level of exercise behavior was measured by the stage of change to exercise in the transtheoretical model. Individual and environmental factors related to exercise behavior were assessed using body mass index, self-efficacy, social support, perceived positive and negative aspects of exercise, perceived neighborhood environment, attitude toward physical education lessons in childhood and puberty, and depression.nnnRESULTSnScores for self-efficacy, social support, positive aspects of exercise, and perceived neighborhood environment were significantly higher among women who were more active compared with those who were inactive. On the other hand, scores for negative aspects of exercise and depression were greater among inactive women compared with those who were insufficiently active and/or active. In addition, past attitude toward exercise in primary school, junior high school, and high school was associated with current level of exercise behavior.nnnCONCLUSIONSnThis cross-sectional study confirmed that psychosocial and environmental factors were closely associated with level of exercise behavior among female Japanese undergraduate students.