Association between Genetic Variation in the TAS2R38 Bitter Taste Receptor and Propylthiouracil Bitter Taste Thresholds among Adults Living in Japan Using the Modified 2AFC Procedure with the Quest Method.

Individual taste sensitivity influences food preferences, nutritional control, and health, and differs greatly between individuals. The purpose of this study was to establish a method of measuring and quantifying an individual's taste sensitivity and to evaluate the relationship between taste variation and genetic polymorphisms in humans using agonist specificities of the bitter taste receptor gene, TAS2R38, with the bitter compound 6-n-propylthiouracil (PROP). We precisely detected the threshold of PROP bitter perception by conducting the modified two-alternative forced-choice (2AFC) procedure with the Bayesian staircase procedure of the QUEST method and examined genetic variation in TAS2R38 in a Japanese population. There were significant differences in PROP threshold between the three TAS2R38 genotype pairs for 79 subjects: PAV/PAV vs AVI/AVI, p < 0.001; PAV/AVI vs AVI/AVI, p < 0.001; and PAV/PAV vs PAV/AVI, p < 0.01. Our results quantified individual bitter perception as QUEST threshold values: the PROP bitter perception of individuals with the PAV/PAV or PAV/AVI genotypes was tens to fifty times more sensitive than that of an individual with the AVI/AVI genotype. Our analyses provide a basic model for the accurate estimation of taste thresholds using the modified 2AFC with the QUEST approach.

Shoulder stiffness, back pain, and wrist pain: Are older primiparas more vulnerable?

AIM: To describe changes in prevalence of shoulder stiffness, back pain, and wrist pain during the first 6 months postpartum, and to examine the association of these symptoms with maternal age and parity. METHODS: Participants were recruited from 13 Japanese hospitals between 2012 and 2013. A total of 2709 (response rate 71.9%) women provided longitudinal data, using self-report questionnaires at 5 time points: during their hospital stay, and at 1, 2, 4, and 6 months postpartum. Shoulder stiffness, back pain, and wrist pain were measured, using checklists with yes-no responses. The effects of age and parity were assessed in 4 groups of younger (<35 years) and older (≥35 years) mothers: 983 younger primiparas, 481 older primiparas, 649 younger multiparas, and 596 older multiparas. Chi-square tests and Cochran's Q tests were used to assess effects of group and time. RESULTS: Prevalence of shoulder stiffness, back pain, and wrist pain during the hospital stay significantly increased up to 1 month postpartum for older primiparas, who were also the most vulnerable to back pain and wrist pain at 1 month postpartum. CONCLUSION: Special attention should be given to older primiparas in assessing and providing nursing care for physical symptoms, especially during the first month postpartum.

Course of maternal fatigue and its associated factors during the first 6 months postpartum: a prospective cohort study.

Aims: To identify the course of maternal fatigue during the first 6 months postpartum and to determine factors associated with it. Design: A prospective cohort study. Methods: Women (N = 2,697) in 13 Japanese hospitals provided longitudinal data using self-report questionnaires at five time points. Maternal fatigue was assessed using the Postnatal Accumulated Fatigue Scale. We focused on the effect of maternal age and parity on the course of maternal fatigue and used a mixed between/within-subjects analysis of variance. Factors associated with maternal fatigue were analysed using stepwise multiple regression. Results: In the 6-month postpartum period, the level of fatigue was highest at 1 month and significantly decreased from 1-4 months postpartum. Primiparas showed a significantly higher level of fatigue than multiparas during hospital stay and their levels of fatigue more closely approximated the 1-month peak. Multiparas showed significantly higher levels of fatigue than younger primiparas at 6-month postpartum. Factors associated with maternal fatigue included satisfaction with sleep, concerns about child-rearing, satisfaction with social support, financial burden and meal times per day.

Postpartum maternal function and parenting stress: Comparison by feeding methods.

AIM: This cross-sectional and longitudinal study explored primiparous mothers' functioning and parenting stress on the basis of infant-feeding method over the first 6 months postpartum. METHODS: Participants were Japanese primiparae who delivered live singleton infants (N = 1120). Questionnaires, completed at 1, 2, 4, and 6 months postpartum, included demographics, feeding method, frequency of feedings, time required from infant's feeding to falling asleep, mother's sleep time, Postnatal Accumulated Fatigue Scale, and the original Japanese version of Parenting Stress Short-Form Scale. Chi-square tests and Welch F tests for one-way analysis of variance were conducted. RESULTS: Exclusively breastfeeding mothers fed their infants more frequently, but required less time from infant's feeding to falling asleep than either mixed or formula-feeding mothers. Mixed feeding mothers required more time for infant feeding and reported more severe fatigue and greater parenting stress than breastfeeding mothers at 1 and 2 months postpartum. Exclusively formula-feeding mothers required more time to get their infant back to sleep and reported greater parenting stress than the other groups at 6 months postpartum. Nearly 25% of mothers continued breastfeeding exclusively through the first 6 months postpartum. Mothers often changed feeding methods, with many exclusively breastfeeding by 6 months. CONCLUSION: Feeding methods may affect maternal functioning and parenting stress across the postpartum period.

Prevalence of postpartum depressive symptoms during the first 6 months postpartum: Association with maternal age and parity.

BACKGROUND: Depressive symptoms are common in postpartum women. The present study aimed to describe changes in the prevalence of depressive symptoms during the first 6 months postpartum, and their association with maternal age and parity. METHODS: A prospective cohort study was conducted with 3769 women at 13 hospitals in Japan. Depressive symptoms were measured during hospital stay and at 1, 2, 4, and 6 months postpartum, using the Japanese version of the Edinburgh Postnatal Depression Scale (EPDS). The effects of maternal age and parity were assessed by comparing four groups: younger primiparas (aged <35 years); older primiparas (≥35 years); younger multiparas (<35 years); and older multiparas (≥35 years). Data were analyzed using a mixed between/within-subjects analysis of variance, Cochran's Q tests, and chi-square tests. RESULTS: Mean EPDS scores significantly decreased from 1 to 2 months postpartum in all groups. The proportion of women with EPDS scores ≥9 significantly decreased during the same period for primiparas but not for multiparas. Primiparas also had significantly higher EPDS scores than multiparas during hospital stay and at 1 month postpartum. LIMITATIONS: As we used convenience sampling, our study sample was not fully representative of Japanese mothers. This study was also limited by our focus on the postpartum period. CONCLUSIONS: The first month postpartum represented peak prevalence for depressive symptoms. Primiparity was a risk factor for depressive symptoms only during the first month postpartum. Healthcare professionals should be sensitive to postpartum duration and parity when monitoring depressive symptoms.

Predictors of depressive symptoms in older Japanese primiparas at 1 month post-partum: A risk-stratified analysis.

AIM: Older maternal age has become more common in Japan. Studies suggest that older maternal age and primiparity are associated with post-partum depression. The present study aimed to identify predictors of post-partum depression in older Japanese primiparas at 1 month post-partum. METHODS: Participants were 479 primiparas aged 35 years and over, drawn from a prospective cohort study. Data were collected using self-report questionnaires. Depression was measured with the Japanese version of the Edinburgh Postnatal Depression Scale. Stepwise logistic regression analysis was conducted on binary outcome variables of depression at 1 month post-partum, along with a stratified analysis based on the risk status of depression. RESULTS: Five predictors were identified: (i) the depression score during hospital stay; (ii) financial burden; (iii) dissatisfaction with appraisal support; (iv) physical burden in daily life; and (v) concerns about infant caretaking. Stratified analysis identified dissatisfaction with instrumental support in the low-risk group, and the Child-care Value Scale score as unique predictors in the high-risk group. CONCLUSION: These results highlight the importance of early assessment of depressive symptoms and the provision of continuous care.

Age-specific determinants of post-partum fatigue in primiparous women.

AIM: Post-partum fatigue is a serious concern for mothers worldwide. The aim of this study was to identify age-specific determinants of self-perceived fatigue after childbirth among Japanese primiparous women. METHODS: A multicenter prospective cohort study was conducted in Japan. The degree of fatigue was assessed using the Postnatal Accumulated Fatigue Scale during the hospital stay after childbirth. Associated factors were stratified into two age groups (<35 or ≥35 years old); data were analyzed using stepwise multiple regression. RESULTS: In the younger group, significant determinants of post-partum fatigue included: anticipated difficulties in child-rearing after discharge; perception of inadequate sleep conditions; dissatisfaction with childbirth; shorter sleep and meal times; longer duration between feeding and infant bedtime; unemployment; and having hyperemesis gravidarum. In the older group, significant determinants of post-partum fatigue included: anticipated difficulties in child-rearing after discharge; perception of inadequate sleep conditions; shorter meal times; formula feeding; and dissatisfaction with childbirth. CONCLUSION: Primiparous mothers who anticipated new life with their infants to be difficult and who had an irregular lifestyle tended to report higher levels of fatigue during the post-partum hospital stay. Nurses and midwives should assess maternal sleep and eating conditions, providing support to ensure adequate maternal rest. Special efforts should be made to reduce anxiety about new life with infants among younger primiparous women who had experienced hyperemesis gravidarum.

Predicting early post-partum depressive symptoms among older primiparous Japanese mothers.

AIM: The number of older primiparas is increasing in Japan. These women have been shown to be more vulnerable to post-partum depression. This study aimed to identify factors for predicting post-partum depressive symptoms during hospitalization after childbirth in Japanese primiparas aged 35 years and over. METHODS: The present authors used the data of 479 primiparas aged 35 years and over from a prospective cohort study. Data were collected using self-report questionnaires on the day before hospital discharge. The questionnaire consisted of: demographics and background information; depressive symptoms; fatigue; maternal confidence and maternal satisfaction; child-care values; physical symptoms; perceptions of daily life during hospitalization; concerns about child care and daily life; and infant feeding. Additionally, vital records data were obtained from the hospitals. A stepwise logistic regression analysis was performed on the binary outcome variable of depressive symptoms, measured by the Japanese version of the Edinburgh Postnatal Depression Scale. Women who scored 9 or more were considered to be at high risk for post-partum depression. The authors obtained informed consent from all participants and institutional ethics approvals before initiating the study. RESULTS: The following six variables reliably predicted the risk of post-partum depression: emergency cesarean section, lower satisfaction with birth experience, higher physical burden in daily life, long-term complications with the newborn, more concerns about newborn caretaking after discharge, and more concerns about one's own life after discharge. CONCLUSION: Recognition of women with these factors will help nurses to identify those at risk for developing post-partum depression and to provide appropriate care during hospitalization after childbirth.

Older Japanese primiparas' experiences at the time of their post-delivery hospital stay.

The purpose of this study was to gain a deeper understanding of the postpartum experiences of older primiparas at the time of their postpartum hospital stay. Participants were Japanese primiparas aged 35-44 years who gave birth, without abnormalities for either the mother or child. Data were obtained using a semi-structured interview with 22 participants. Thirteen themes emerged through content analysis. We found that there were distinctive experiences, which included 'the health and growth of the baby: relief and continued anxiety', 'awareness of strengths and of concerns of primiparas', 'meaning of the pregnancy and childbirth experience' and 'developing one's own child-care approach'. Findings suggest that nursing care during the post-delivery hospital stay should use the unique strengths of older primiparas to enable their smooth transition to maternal role attainment.

Genetic differentiation and genetic diversity of Castanopsis (Fagaceae), the dominant tree species in Japanese broadleaved evergreen forests, revealed by analysis of EST-associated microsatellites.

The broadleaved evergreen forests of the East Asian warm temperate zone are characterised by their high biodiversity and endemism, and there is therefore a need to extend our understanding of its genetic diversity and phylogeographic patterns. Castanopsis (Fagaceae) is one of the dominant tree species in the broadleaved evergreen forests of Japan. In this study we investigate the genetic diversity, genetic structure and leaf epidermal morphology of 63 natural populations of C. sieboldii and C. cuspidata, using 32 Expressed Sequence Tag associated microsatellites. The overall genetic differentiation between populations was low (GST = 0.069 in C. sieboldii and GST = 0.057 in C. cuspidata). Neighbor-joining tree and Bayesian clustering analyses revealed that the populations of C. sieboldii and C. cuspidata were genetically clearly differentiated, a result which is consistent with the morphology of their epidermal cell layers. This suggests that C. sieboldii and C. cuspidata should be treated as independent species, although intermediate morphologies are often observed, especially at sites where the two species coexist. The higher level of genetic diversity observed in the Kyushu region (for both species) and the Ryukyu Islands (for C. sieboldii) is consistent with the available fossil pollen data for Castanopsis-type broadleaved evergreen trees during the Last Glacial Maximum and suggests the existence of refugia for Castanopsis forests in southern Japan. Within the C. sieboldii populations, Bayesian clustering analyses detected three clusters, in the western and eastern parts of the main islands and in the Ryukyu Islands. The west-east genetic differentiation observed for this species in the main islands, a pattern which is also found in several plant and animal species inhabiting Castanopsis forests in Japan, suggests that they have been isolated from each other in the western and eastern populations for an extended period of time, and may imply the existence of eastern refugia.

Comparative phylogeography of four component species of deciduous broad-leaved forests in Japan based on chloroplast DNA variation.

A phylogeographic study of four tree species (Padus grayana, Euonymus oxyphyllus, Magnolia hypoleuca, and Carpinus laxiflora) growing in Japanese deciduous broad-leaved forests was conducted based on chloroplast DNA (cpDNA) variations. Using nucleotide sequences of 702-1,059 bp of intergenic spacers of cpDNA, 20, 27, eight, and eight haplotypes were detected among 251, 251, 226, and 262 individuals sampled from 67, 79, 75, and 71 populations of the above species, respectively. The geographical pattern of the cpDNA variations was highly structured in each species, and the following three regional populations were genetically highly differentiated among all four species: (1) the Sea of Japan-side area, (2) the Kanto region, and (3) southwestern Japan. Based on some interspecific similarities among the phylogeographic patterns, the following migration scenario of Japanese deciduous broad-leaved forests was postulated. During the last glacial maximum (LGM), the forests were separately distributed in six regions. After LGM, as the climate warmed, the forests in eastern Japan separately expanded from each of the refugia along the Sea of Japan-side or along the Pacific Ocean-side. In contrast, those in southwestern Japan retreated and moved to high altitudes from each of the continuous forests.

Phylogeography of Phytophagous Weevils and Plant Species in Broadleaved Evergreen Forests: A Congruent Genetic Gap between Western and Eastern Parts of Japan.

The Quaternary climate cycles played an important role in shaping the distribution of biodiversity among current populations, even in warm-temperate zones, where land was not covered by ice sheets. We focused on the Castanopsis-type broadleaved evergreen forest community in Japan, which characterizes the biodiversity and endemism of the warm-temperate zone. A comparison of the phylogeographic patterns of three types of phytophagous weevils associated with Castanopsis (a host-specific seed predator, a generalist seed predator, and a host-specific leaf miner) and several other plant species inhabiting the forests revealed largely congruent patterns of genetic differentiation between western and eastern parts of the main islands of Japan. A genetic gap was detected in the Kii Peninsula to Chugoku-Shikoku region, around the Seto Inland Sea. The patterns of western-eastern differentiation suggest past fragmentation of broadleaved evergreen forests into at least two separate refugia consisting of the southern parts of Kyushu to Shikoku and of Kii to Boso Peninsula. Moreover, the congruent phylogeographic patterns observed in Castanopsis and the phytophagous insect species imply that the plant-herbivore relationship has been largely maintained since the last glacial periods. These results reinforce the robustness of the deduced glacial and postglacial histories of Castanopsis-associated organisms.

Phylogeographical patterns of a generalist acorn weevil: insight into the biogeographical history of broadleaved deciduous and evergreen forests.

BACKGROUND: Climatic changes during glacial periods have had a major influence on the recent evolutionary history of living organisms, even in temperate forests on islands, where the land was not covered with ice sheets. We investigated the phylogeographical patterns of the weevil Curculio sikkimensis (Curculionidae), a generalist seed predator of Fagaceae plants living in both deciduous oak and evergreen forests of Japan. Its genetic structure was compared to that of another host-specific seed predator, C. hilgendorfi, inhabiting only evergreen forests. RESULTS: We examined 921 bp of mitochondrial DNA for 115 individuals collected from 33 populations of C. sikkimensis from 11 plant species of three genera, Quercus, Lithocarpus, and Castanopsis. An analysis of molecular variance revealed that a large proportion (almost 50%, P < 0.001) of the total genetic variance could be explained by differences between two geographical regions, the southwestern and northeastern parts of the main islands of Japan. In contrast, no significant genetic differentiation of the weevil was observed among vegetation types of their utilized host plant species. The phylogeographical patterns of the generalist and the host-specific seed predator exhibited a congruent genetic boundary in the Chugoku-Shikoku region. CONCLUSION: Our results suggest that geology and historical environment have contributed to shaping the present genetic structure of C. sikkimensis. The geographical patterns of genetic differentiation in the Chugoku-Shikoku region observed in the two types of Fagaceae-associated Curculio in this study have also been observed in several plant species growing in warm and cool temperate zones of Japan. The occurrence of this common pattern suggests that deciduous oak and evergreen forests of Japan survived together, or adjacent to each other, in small refugia during glacial ages, in the southwestern and northeastern parts of the main islands, although these two types of forests are presently distributed in cool and warm temperate zones of Japan, respectively.

Intraspecific sequence variation of chloroplast DNA among the component species of deciduous broad-leaved forests in Japan.

To select appropriate plant materials for a phylogeography of deciduous broad-leaved forests in Japan, we surveyed intraspecific chloroplast DNA variation in 34 species found in these forests. A relatively large number of intraspecific cpDNA variations were detected in ten species: Carpinus japonica (nucleotide diversity pi=0.00083), C. laxiflora (pi=0.00221), Magnolia obovata (pi=0.00134), Lindera triloba (pi=0.00255), L. obtusiloba (pi=0.00289), Pourthiaea villosa var. leavis (pi=0.00263), Acer japonicum (pi=0.00170), A. micranthum (pi=0.00237), Euonymus oxyphyllus (pi=0.00322) and Styrax obassia (pi=0.00100).

Chloroplast DNA phylogeography of Photinia glabra (Rosaceae) in Japan.

Climate changes during glacial periods have had significant effects on the present geographic distribution of plant species. To elucidate the evolutionary history of a plant species with a disjunctive distribution, we investigated the geographic distribution patterns of cpDNA haplotypes in Photinia glabra (Rosaceae) growing in broadleaved evergreen forests in Japan. We examined cpDNA in 42 populations of P. glabra sampled over a geographic range that included Kinki and its surrounding areas and the disjunctive regions in the Amakusa Islands. Both areas had unique cpDNA haplotypes. Moreover, the AMOVA revealed that a large proportion of the total variance (51%, P < 0.001) could be explained by differences among these regions. These results suggest a past fragmentation of this plant species into two separate refugia: southwestern Kyushu and Kinki, including the surrounding area, during the Quaternary glacial periods. A particularly interesting result was that in the southern disjunct distribution in the Amakusa Islands, the genetic subdivision (Φ(CT) = 1.00, P < 0.001) appears to lie between the populations from nearly contiguous islands located across a fairway only approximately 80 to 150 m in width.

Phylogeography of the component species of broad-leaved evergreen forests in Japan, based on chloroplast DNA variation.

In order to elucidate the past distribution and colonization routes of broad-leaved evergreen (lucidophyllous) forests, we investigated the intraspecific phylogeographic patterns of lucidophyllous forests in Japan and surrounding areas. We selected 6 component species with a similar geographic distributions growing in Castanopsis-dominant forests. We defined possible important refugia during the glacial periods as the regions rich in rare haplotypes (with a frequency of 5% or less), or as regions rich in the number of common haplotypes (with a frequency of more than 5%). We then located the sites of refuge by comparing the intraspecific phylogeographic patterns among 6 component species of lucidophyllous forests with respect to these two parameters (i.e., haplotype uniqueness and the number of haplotypes). The following results were obtained during the course of this study: (1) rare haplotypes were distributed among islands around the main islands of Japan; (2) rare subtypes and the greatest numbers of common haplotypes were observed in Kyushu, a finding which agreed with fossilized pollen data demonstrative of the past existence of refugia in southern Kyushu; and (3) rare haplotypes were found on the Muroto Peninsula, and the second greatest numbers of common haplotypes were observed on the Kii Peninsula, a finding which suggested the existence of additional important refugia along the Pacific coast of Japan during the glacial ages.

Intraspecific sequence variation of chloroplast DNA among the component species of evergreen broad-leaved forests in Japan.

For the purpose of phylogeographic study of lucidophyllous (evergreen broad-leaved) forests in Japan, we surveyed intraspecific chloroplast DNA (cpDNA) variation in 41 component species of such forests. Intraspecific cpDNA variations were detected in 14 species. In 15 species and one species group, 16 non-coding cpDNA regions were examined to find intraspecific sequence variation. The extent of variation in these regions was compared. The largest amount of intraspecific variation was detected in the rps16 region. A relatively large amount of intraspecific variation was detected in the petD-rpoA, rpl16, and trnL-F regions. It is suggested that these regions of cpDNA would be useful for detecting intraspecific variation in plant species, and could provide valuable information for various research purposes.