Complete sequence and gene organization of the genome of a hyper-thermophilic archaebacterium, Pyrococcus horikoshii OT3

The complete sequence of the genome of a hyper-thermophilic archaebacterium, Pyrococcus horikoshii OT3, has been determined by assembling the sequences of the physical map-based contigs of fosmid clones and of long polymerase chain reaction (PCR) products which were used for gap-filling. The entire length of the genome was 1,738,505 bp. The authenticity of the entire genome sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA. As the potential protein-coding regions, a total of 2061 open reading frames (ORFs) were assigned, and by similarity search against public databases, 406 (19.7%) were related to genes with putative function and 453 (22.0%) to the sequences registered but with unknown function. The remaining 1202 ORFs (58.3%) did not show any significant similarity to the sequences in the databases. Sequence comparison among the assigned ORFs in the genome provided evidence that a considerable number of ORFs were generated by sequence duplication. By similarity search, 11 ORFs were assumed to contain the intein elements. The RNA genes identified were a single 16S-23S rRNA operon, two 5S rRNA genes and 46 tRNA genes including two with the intron structure. All the assigned ORFs and RNA coding regions occupied 91.25% of the whole genome. The data presented in this paper are available on the internet at http:@www.nite.go.jp.

Complete genome sequence of an aerobic hyper-thermophilic crenarchaeon, Aeropyrum pernix K1

The complete sequence of the genome of an aerobic hyper-thermophilic crenarchaeon, Aeropyrum pernix K1, which optimally grows at 95 degrees C, has been determined by the whole genome shotgun method with some modifications. The entire length of the genome was 1,669,695 bp. The authenticity of the entire sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA. As the potential protein-coding regions, a total of 2,694 open reading frames (ORFs) were assigned. By similarity search against public databases, 633 (23.5%) of the ORFs were related to genes with putative function and 523 (19.4%) to the sequences registered but with unknown function. All the genes in the TCA cycle except for that of alpha-ketoglutarate dehydrogenase were included, and instead of the alpha-ketoglutarate dehydrogenase gene, the genes coding for the two subunits of 2-oxoacid:ferredoxin oxidoreductase were identified. The remaining 1,538 ORFs (57.1%) did not show any significant similarity to the sequences in the databases. Sequence comparison among the assigned ORFs suggested that a considerable member of ORFs were generated by sequence duplication. The RNA genes identified were a single 16S-23S rRNA operon, two 5S rRNA genes and 47 tRNA genes including 14 genes with intron structures. All the assigned ORFs and RNA coding regions occupied 89.12% of the whole genome. The data presented in this paper are available on the internet homepage (http://www.mild.nite.go.jp).

Complete genome sequence of an aerobic thermoacidophilic crenarchaeon, Sulfolobus tokodaii strain7

The complete genomic sequence of an aerobic thermoacidophilic crenarchaeon, Sulfolobus tokodaii strain7 which optimally grows at 80 degrees C, at low pH, and under aerobic conditions, has been determined by the whole genome shotgun method with slight modifications. The genomic size was 2,694,756 bp long and the G + C content was 32.8%. The following RNA-coding genes were identified: a single 16S-23S rRNA cluster, one 5S rRNA gene and 46 tRNA genes (including 24 intron-containing tRNA genes). The repetitive sequences identified were SR-type repetitive sequences, long dispersed-type repetitive sequences and Tn-like repetitive elements. The genome contained 2826 potential protein-coding regions (open reading frames, ORFs). By similarity search against public databases, 911 (32.2%) ORFs were related to functional assigned genes, 921 (32.6%) were related to conserved ORFs of unknown function, 145 (5.1%) contained some motifs, and remaining 849 (30.0%) did not show any significant similarity to the registered sequences. The ORFs with functional assignments included the candidate genes involved in sulfide metabolism, the TCA cycle and the respiratory chain. Sequence comparison provided evidence suggesting the integration of plasmid, rearrangement of genomic structure, and duplication of genomic regions that may be responsible for the larger genomic size of the S. tokodaii strain7 genome. The genome contained eukaryote-type genes which were not identified in other archaea and lacked the CCA sequence in the tRNA genes. The result suggests that this strain is closer to eukaryotes among the archaea strains so far sequenced. The data presented in this paper are also available on the internet homepage (http://www.bio.nite.go.jp/E-home/genome_list-e.html/).

A dose-response relationship between short sleeping hours and childhood obesity: results of the Toyama Birth Cohort Study

BACKGROUND

Short sleeping hours could cause obesity through increased sympathetic activity, elevated cortisol secretion and decreased glucose tolerance. The aim of this study was to clarify parental and lifestyle factors, particularly sleeping habits, associated with obesity in Japanese children.

METHODS

Between June and July 1996, 8274 children (4194 males and 4080 females) aged 6-7 years living in Toyama prefecture, Japan, were investigated by questionnaire survey and the collection of anthropometric data. Subjects with a body mass index (BMI; weight in kg divided by square of height in m) greater than the age- and sex-specific cut-off points linked to adulthood overweight (BMI of 25 kg/m2 or more) were defined as obese subjects. Parental obesity was defined as a BMI of 25 kg/m2 or more. Logistic regression analysis was performed to evaluate the strength of the relationships between parental obesity or lifestyle factors and childhood obesity, adjusted for possible confounding factors.

RESULTS

Parental obesity, long hours of TV watching and physical inactivity were significantly associated with childhood obesity. Although wake-up time was not related to obesity, there was a significant dose-response relationship between late bedtime or short sleeping hours and childhood obesity. Compared with children with 10 or more hours of sleep, the adjusted odds ratio was 1.49 (95% confidence interval 1.08-2.14) for those with 9-10 h sleep, 1.89 (1.34-2.73) for those with 8-9 h sleep and 2.87 (1.61-5.05) for those with <8 h sleep, after adjustment for age, sex, parental obesity and other lifestyle factors.

CONCLUSION

A strong inverse association was observed in the relationship between sleeping hours and childhood obesity. Longitudinal research will be required to confirm this causality.

Snurportin1, an m3G-cap-specific nuclear import receptor with a novel domain structure

The nuclear import of the spliceosomal snRNPs U1, U2, U4 and U5, is dependent on the presence of a complex nuclear localization signal (NLS). The latter is composed of the 5'-2,2,7-terminal trimethylguanosine (m3G) cap structure of the U snRNA and the Sm core domain. Here, we describe the isolation and cDNA cloning of a 45 kDa protein, termed snurportin1, which interacts specifically with m3G-cap but not m7G-cap structures. Snurportin1 enhances the m3G-capdependent nuclear import of U snRNPs in both Xenopus laevis oocytes and digitonin-permeabilized HeLa cells, demonstrating that it functions as an snRNP-specific nuclear import receptor. Interestingly, solely the m3G-cap and not the Sm core NLS appears to be recognized by snurportin1, indicating that at least two distinct import receptors interact with the complex snRNP NLS. Snurportin1 represents a novel nuclear import receptor which contains an N-terminal importin beta binding (IBB) domain, essential for function, and a C-terminal m3G-cap-binding region with no structural similarity to the arm repeat domain of importin alpha.

Conformational rigidity of specific pyrimidine residues in tRNA arises from posttranscriptional modifications that enhance steric interaction between the base and the 2'-hydroxyl group

In order to elucidate roles of the 2'-O-methylation of pyrimidine nucleotide residues of tRNAs, conformations of 2'-O-methyluridylyl(3'----5')uridine (UmpU), 2'-O-methyluridine 3'-monophosphate (Ump), and 2'-O-methyluridine (Um) in 2H2O solution were analyzed by one- and two-dimensional proton NMR spectroscopy and compared with those of related nucleotides and nucleoside. As for UpU and UmpU, the 2'-O-methylation was found to stabilize the C3'-endo form of the 3'-nucleotidyl unit (Up-/Ump-moiety). This stabilization of the C3'-endo form is primarily due to an intraresidue effect, since the conformation of the 5'-nucleotidyl unit (-pU moiety) was only slightly affected by the 2'-O-methylation of the 3'-nucleotide unit. In fact even for Up and Ump, the 2'-O-methylation significantly stabilizes the C3'-endo form by 0.8 kcal/.mol-1. By contrast, for nucleosides (U and Um), the C3'-endo form is slightly stabilized by 0.1 kcal/.mol-1. Accordingly, the stabilization of the C3'-endo form by the 2'-O-methylation is primarily due to the steric repulsion among the 2-carbonyl group, the 2'-O-methyl group and the 3'-phosphate group in the C2'-endo form. For some tRNA species, 2-thiolation of pyrimidine residues is found in positions where the 2'-O-methylation is found for other tRNA species.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors contributing to the progression of visual field damage in eyes with normal-tension glaucoma

PURPOSE

To evaluate the contribution of various factors on the progression of visual field damage in normal-tension glaucoma.

METHODS

Follow-up data of 56 eyes of 56 patients with normal-tension glaucoma, all of whom had an early stage of the disease with a mean deviation of -5 decibels or greater and were followed without therapy, were analyzed using regression analysis of survival data based on the Cox proportional hazards model. Factors studied were age, sex, presence or absence of diabetes or family history of glaucoma, refraction, systolic and diastolic pressures, cup:disc ratio, ratio of area of parapapillary atrophy to disc area, the mean deviations of the studied and contralateral eyes, and intraocular pressure and occurrence of disc bleeding during follow-up, both of which were treated as time-dependent variables. The progression of visual field damage was based on the glaucoma change probability analysis.

RESULTS

Cup:disc ratio, ratio of area of parapapillary atrophy to disc area, and intraocular pressure were found to have significant influence on the progression of visual field damage in normal-tension glaucoma.

CONCLUSION

Intraocular pressure may be involved in the development of normal-tension glaucoma. However, further prospective studies are needed to determine the validity of such a conclusion.

Nucleo-cytoplasmic transport of U snRNPs: definition of a nuclear location signal in the Sm core domain that binds a transport receptor independently of the m3G cap

We have investigated the nuclear transport of U1 and U5 snRNPs by microinjection studies in oocytes from Xenopus laevis using snRNP particles prepared by reconstitution in vitro. Competition studies with snRNPs showed that the Sm core domain of U1 snRNPs contains a nuclear location signal that acts independently of the m3G cap. The transport of U1 snRNP can be blocked by saturation with competitor U1 snRNPs or by U5 snRNPs, which indicates that the signals on the respective Sm core domains interact with the same transport receptors. Further, by using a minimal U1 snRNP particle reconstituted in vitro and containing only the Sm core RNP domain and lacking stem-loops I to III of U1 RNA, we show that this is targeted actively to the nucleus, in spite of the absence of the m3G cap. This indicates that under certain conditions the NLS in the Sm core domain not only is an essential, but may also be a sufficient condition for nuclear targeting. We propose that the RNA structure of a given snRNP particle determines at least in part whether the particle's m3G cap is required for nuclear transport or can be dispensed with.

Associations of job strain and working overtime with adverse health behaviors and obesity: evidence from the Whitehall II Study, Helsinki Health Study, and the Japanese Civil Servants Study

Adverse health behaviors and obesity are key determinants of major chronic diseases. Evidence on work-related determinants of these behavioral risk factors is inconclusive, and comparative studies are especially lacking. We aimed to examine the associations between job strain, working overtime, adverse health behaviors, and obesity among 45-60-year-old white-collar employees of the Whitehall II Study from London (n=3,397), Helsinki Health Study (n=6,070), and the Japanese Civil Servants Study (n=2,213). Comparable data from all three cohorts were pooled, and logistic regression analysis was used, stratified by cohort and sex. Models were adjusted for age, occupational class, and marital status. Outcomes were unhealthy food habits, physical inactivity, heavy drinking, smoking, and obesity. In London, men reporting passive work were more likely to be physically inactive. A similar association was repeated among women in Helsinki. Additionally, high job strain was associated with physical inactivity among men in London and women in Helsinki. In London, women reporting passive work were less likely to be heavy drinkers and smokers. In Japan, men working overtime reported less smoking, whereas those with high job strain were more likely to smoke. Among men in Helsinki the association between working overtime and non-smoking was also suggested, but it reached statistical significance in the age-adjusted model only. Obesity was associated with working overtime among women in London. In conclusion, job strain and working overtime had some, albeit mostly weak and inconsistent, associations with adverse health behaviors and obesity in these middle-aged white-collar employee cohorts from Britain, Finland, and Japan.

Morning‐Evening Preference: Sleep Pattern Spectrum and Lifestyle Habits Among Japanese Junior High School Pupils

We surveyed the sleep-wake patterns and lifestyle habits in a sample of Japanese first to third year junior high school children (n=638, age 12 to 15 yrs), of whom 29.3% were evening type, 64.1% intermediate type, and 6.6% morning type in preference. The morningness-eveningness (M-E) score was lower (more evening typed), 16.1 vs. 15.4 in first compared to third year students. There were significant gender differences, with girls showing a greater evening preference. Evening preference was associated with longer sleep latency, shortened sleep duration during schooldays and weekends, bad morning feeling, and episodes of daytime sleepiness. In contrast, morning preference was associated with higher sleep drive and better sleep-wake parameters and lifestyle habits. Our results suggest the morning preference should be promoted among junior high school children to increase the likelihood of more regular sleep-wake patterns and lifestyle habits.

Work and family characteristics as determinants of socioeconomic and sex inequalities in sleep: The Japanese Civil Servants Study

STUDY OBJECTIVE

To clarify whether socioeconomic and sex inequalities in poor sleep quality are explained by socioeconomic and sex differences in work and family characteristics.

DESIGN

A cross-sectional study.

PARTICIPANTS

Three thousand five hundred fifty-six employees (2397 men and 1159 women) aged 20 to 65 years in local government in Japan.

MEASUREMENTS

Respondents completed a self-administered questionnaire that asked about sleep quality, as measured by the Pittsburgh Sleep Quality Index; work characteristics, as measured by the job-demand-control-support model, work hours, and shift work; and family characteristics, such as family structure and family-work conflicts.

RESULTS

Lower control at work, higher work demands, lower social support, shorter and longer working hours, shift work, being single, higher family-to-work conflict, and higher work-to-family conflict were independently associated with poorer sleep quality in both men and women. In men, the age-adjusted odds ratio (OR) of low-grade employees for poor sleep quality was 1.64 (95% confidence interval: 1.14-2.36) in comparison with high-grade employees. The difference in sleep was attenuated when work and family characteristics were adjusted for (OR=1.25 [0.84-1.86]). Among women, there was no significant grade difference in sleep. Women tended to have poorer sleep quality than men (the age-adjusted OR=1.75 [1.49-2.06]). The sex difference was attenuated and no longer significant when adjustments were made for work and family characteristics (OR=1.04 [0.85-1.27]).

CONCLUSIONS

The results of this study suggest that work and family characteristics may be important for reducing socioeconomic and sex inequalities in sleep. Sex differences in the pattern of socioeconomic inequalities in sleep deserve further research.

Lifestyles and health-related quality of life in Japanese school children: a cross-sectional study

BACKGROUND

Lifestyles are associated with physical and mental health status, as well as health-related quality of life (QOL) in adults. There is little information about relation between lifestyles and QOL in children. This study aims to examine the correlation among Japanese children.

METHODS

Subjects were from the Toyama Birth Cohort Study, a prospective, longitudinal survey of children born between 1989 and 1990 in Toyama Prefecture, Japan. When children were 12-13 years in 2002, a cross-sectional questionnaire-based survey was administered. The questionnaire designed to measure lifestyles included questions on eating, physical activity, sleep, and other factors. For QOL measurement, a validated Japanese version of the COOP Charts was used. Data from 7,887 children were available and logistic regression analyses were used.

RESULTS

Children with undesirable lifestyles, such as skipping breakfast, less participation in physical activity, longer television viewing, and later bedtime, were more likely to have poor QOL in domains of physical fitness, feelings, overall health, and quality of life. These correlations were independent of sex, BMI, social background, and somatic symptoms.

CONCLUSIONS

Undesirable lifestyles are positively associated with impaired QOL among children. Further understanding of these relationships will facilitate the development of interventions to help children with poor QOL.

Parental obesity, lifestyle factors and obesity in preschool children: results of the Toyama Birth Cohort study

The aim of this study was to clarify the impact of parental obesity and lifestyle factors on obesity in preschool children. The subjects consisted of 8941 children aged 3 years, born in 1989. Anthropometric measurements and questionnaire surveys were conducted between 1992 and 1994. Subjects of body mass index (BMI; (weight (kg))/(height (m))2) more than the age- and sex-specific centiles linked to adult overweight were defined as obese subjects. Parental obesity was defined as BMI of 25 kg/m2 or more. Logistic regression analysis was performed to clarify the strengths of parental and lifestyle factors on childhood obesity, adjusted for possible confounding factors. Odds ratios (ORs) of paternal and maternal obesity for childhood obesity were 1.70(1.43-2.02) and 2.56(2.07-3.17), respectively. There was a dose-response relationship between short sleeping hours and obesity. Compared to subjects taking 11 hours sleep or more, the adjusted OR was 1.20(0.97-1.49) for those taking 10 to 11 hours sleep, 1.34(1.05-1.72) for those taking 9 to 10 hours sleep, and 1.57(0.90-2.75) for those taking less than 9 hours sleep. Eating and exercising habits were not significantly associated with obesity. These results indicate that parental obesity and short sleeping hours are possible risk factors for obesity in preschool children.

Isolation and characterization of the E2F-like gene in plants

The transcription factor E2F regulates the expression of genes involved in the progression of G1/S transition and DNA replication in mammalian cells. We cloned and characterized a cDNA (NtE2F) corresponding to a E2F homolog of tobacco (Nicotiana tabacum). The transcription of NtE2F was induced as cells progressed from G1 to the S phase and expressed much earlier than that of the proliferating cell nuclear antigen (PCNA) gene. We demonstrated that NtE2F can interact with the tobacco retinoblastoma (Rb)-related protein in a yeast two-hybrid assay. To further characterize NtE2F, the trans-activation activity of NtE2F was examined by using a transient assay in the tobacco Bright Yellow-2 (BY-2) cells with NtE2F fused to the DNA-binding domain of the veast transcriptional activator GAL4. NtE2F activated the transcription of the beta-glucuronidase (GUS) reporter gene driven by a cauliflower mosaic virus (CaMV) 35S core promoter containing the GAL4-binding sequence. This is the first report of the identification of a functionally equivalent E2F-like gene in plants.

Abnormality of long-chain fatty acids in erythrocyte membrane sphingomyelin from patients with adrenoleukodystrophy

We have devised an analytical method for the determination of fatty acid composition of erythrocyte membrane sphingomyelin by chemical ionization mass spectrometry combined with capillary column gas-liquid chromatography. Fatty acid composition of erythrocyte membrane sphingomyelin from 8 patients with adrenoleukodystrophy (ALD) and 16 healthy controls were examined by this method. The ratio of hexacosanoic acid (C26:0) to docosanoic acid (C22:0) in erythrocyte membrane sphingomyelin from ALD patients was 2.6-fold higher than that of the controls. This result suggests that biochemical diagnosis of ALD is possible by the analysis of fatty acid composition of erythrocyte membrane sphingomyelin. Furthermore, it demonstrates that biochemical abnormality in ALD is the generalized abnormal metabolism of very long-chain saturated fatty acids.

Daytime sleepiness and associated factors in Japanese school children

OBJECTIVE

To examine daytime sleepiness and sleepiness interrelationship with sleep-wake patterns, eating habits, physical activity, and TV/video game time.

STUDY DESIGN

A cross-sectional survey with 9,261 school children (mean age of 12.8 years) from 93 junior high schools in Toyama prefecture, Japan.

RESULTS

The main outcome measures were daytime sleepiness during schooldays and sleepiness interrelationship with sleep-wake patterns, eating habits, physical activity, and visual media use. A total of 2,328 children (25.2%) reported sleepiness almost always and 4,401 (47.6%) sleepiness often. Regarding sex difference, a higher proportion of girls reported sleepiness in comparison to boys (79% vs 66%, P < .001). Higher body mass index values were associated with the presence of sleepiness. In girls with preferences for daily snack (versus those who reported no snack) sleepiness presented significantly (P < .001) higher values. Reduced sleep time was significantly associated with sleepiness. The prevalence of sleepiness did not significantly differ among groups who had 7.5 hours sleep or more. A dose-response relation was found between sleepiness and sleep disturbances, physical activity, and media use time.

CONCLUSIONS

Sleep insufficiency represents a main cause for daytime sleepiness in Japanese junior high school children. Proper sleep habits, high physical activity level, and limited TV viewing time should be promoted among school children.

Lifestyle and overweight among Japanese adolescents: the Toyama Birth Cohort Study

OBJECTIVE

To investigate the effects of lifestyle factors on overweight among Japanese adolescents.

METHODS

We studied 5753 junior high school students (2842 boys and 2911 girls) aged 12 to 13 years. The students were residents of Toyama prefecture, Japan and completed a questionnaire about their height, weight, and lifestyle factors, in June and July 2002. Subjects with a body-mass index (BMI) higher than age- and sex-specific cut-off points were defined as obese. Parental overweight was defined as a BMI of 25 or higher. Logistic regression analysis was used to examine associations between lifestyle factors and overweight.

RESULTS

Skipping breakfast, eating quickly, excessive eating, physical inactivity, and long hours of TV watching were positively and significantly associated with overweight in both sexes. There was a negative association between snacking and overweight in girls (P<0.001); no such association was found in boys (P>0.05). Nighttime snacking was negatively associated with overweight in boys and girls (P<0.05). Extended video game playing (>or=2 hours; OR=2.00, P=0.012) and short sleep duration (<7 hours; OR=1.81, P=0.004) were significantly associated with overweight in girls only. The respective risks of overweight that derived from the subjects' fathers and mothers were 2.0 and 2.5 times, respectively, in boys and 1.9 and 3.0 times in girls.

CONCLUSIONS

Parental overweight, skipping breakfast, eating quickly, excessive eating, long hours of TV watching, long hours of video game playing, physical inactivity, and short sleep duration were associated with adolescent overweight. Furthermore, there were significant negative associations between adolescent overweight and snacking in girls and nighttime snacking in both sexes.

Classification of waist-acceleration signals in a continuous walking record

We attempted to distinguish walking on level ground from walking on a stairway using waist acceleration signals. A triaxial accelerometer was fixed to the subject's waist and the three acceleration signals were recorded by a portable data logger at a sampling rate of 256 Hz. Twenty healthy male subjects were asked to walk through a corridor and up and down a stairway as a single sequence, without any instruction. The data were analyzed using discrete wavelet transform. Walking patterns were classified in two stages. In the first stage, the times when the walking pattern changed were detected using the low-frequency component of the anteroposterior acceleration (LF(A)) and of the vertical acceleration (LF(V)). In the second stage, the three types of walking patterns were classified by comparing powers of wavelet coefficients in the vertical direction (P(WCV)) and in the anteroposterior direction (RP(WCA)). Changes in walking patterns could be detected by using either LF(A) or LF(V). Walking down stairs could be distinguished from the other types of walking as it gave the largest value in P(WCV), and walking up stairs could be discriminated from level walking using RP(WCA). Level and stairway walking could be classified from continuous records of waist acceleration.

Tobacco retinoblastoma-related protein phosphorylated by a distinct cyclin-dependent kinase complex with Cdc2/cyclin D in vitro

The retinoblastoma (Rb) protein was originally identified as a product of a tumour suppressor gene that plays a pivotal role in regulating both the cell cycle and differentiation in mammals. The growth-suppressive activity of Rb is regulated by phosphorylation with cyclin-dependent kinase (CDK), and inactivation of the Rb function is one of the critical steps for transition from the G1 to the S phase. We report here the cloning of a cDNA (NtRb1) from Nicotiana tabacum which encodes a Rb-related protein, and show that this gene is expressed in all the organs examined at the mRNA level. We have demonstrated that NtRb1 interacts with tobacco cyclin D by using yeast two-hybrid and in vitro binding assays. In mammals, cyclin D can assemble with CDK4 and CDK6, but not with Cdc2, to form active complexes. Surprisingly, tobacco cyclin D and Cdc2 proteins can form a complex in insect cells, which is able to phosphorylate tobacco Rb-related protein in vitro. Using immunoprecipitation with the anti-cyclin D anti-body, cyclin D can be found in a complex with Cdc2 in suspension-cultured tobacco BY-2 cells. These results suggest that the cdc2 gene modulates the cell cycle through the phosphorylation of Rb-related protein by forming an active complex with cyclin D in plants.

Analysis of factors that influence body mass index from ages 3 to 6 years: A study based on the Toyama cohort study

BACKGROUND

The aim of the present study was to elucidate both environmental and behavioral factors that influence body mass index (BMI, kg/m2) among Japanese children from ages 3-6.

METHODS

In 1992 (at age 3) and 1995 (at age 6), 8170 6-year-old children (4176 boys and 3994 girls) were surveyed using a questionnaire on both body build (height and weight) and lifestyle. The correlation between BMI for 3-year-olds and for 6-year-olds were analyzed. From the temporal changes of body build between age 3 and 6 years, we categorized children into four groups: group 1, normal at both age 3 years and 6 years (normal/normal); group 2, overweight at age 3 years and normal at age 6 years (overweight/normal); group 3, normal at age 3 years and overweight at age 6 years (normal/overweight); and group 4, overweight at both age 3 years and 6 years (overweight/overweight). The authors compared the four groups with each other according to sex, concerning frequencies of children who matched the categories of environmental and behavioral factors. Each factor was tested using the chi2 test. Overweight children were defined as those whose BMI value was age-sex specific in the 90th percentile or more.

RESULTS

A significant correlation was found between body builds for children aged 3 and 6 years in both genders (boys, r = 0.559, P < 0.01; girls, r = 0.584, P < 0.01). Significant factors associated with overweight children were diet (eating rice, green tea, eggs, meat, but less breads and juice), rapid eating, short sleep duration, early bedtime, long periods of television viewing, avoidance of physical activity, and frequent bowel movement.

DISCUSSION

Temporal changes in BMI from age 3 years to 6 years are significantly associated with both environmental and behavioral factors at age 6 years. The results of this study may be useful for health promotion programs designed to prevent obesity during the early stages of childhood.

A study of weekly and seasonal variation of stroke onset

A registry based study was conducted to assess the variation in first-onset stroke with weekdays and seasons, in relation to the effects of age. Between 1 December 1991 and 30 November 1998, 10,729 first-onset stroke patients aged 25 or more were registered in Toyama Prefecture, Japan. We compared the weekly and seasonal variation in first-onset stroke by a one-way goodness-of-fit chi(2)-test. The relationship between seasonal variation in stroke onset and age was also evaluated by the method of Kendall's tau-b R x C tables with ordered categories. The frequency of onset of all strokes and cerebral infarctions (CI) was significantly higher on weekdays than at weekends (P < 0.01). More men had strokes and CI on a Monday (P < 0.01), and more women had cerebral hemorrhage (CH) on a Monday and CI at the end of the week. Stroke incidence was higher in patients aged less than 60 years (20.6%) than in those aged 60 years or over (18.7%) on a Monday compared to the weekend. By chi(2)-test, comparing observed with expected numbers of stroke onsets, weighted by the number of days in each 3-month period, the incidence of all strokes, CI and CH was significantly higher in winter and spring than in summer. The seasonal variation in the onset of stroke declined with age: all strokes (P < 0.001) and CH (P < 0.001) in both genders; subarachnoid hemorrhage (P < 0.001) only in men. Our study shows that the onset of stroke is more frequent on weekdays than on weekends, and may be associated with changes in psychophysiological stresses between working days and the weekend. We also observed a clear negative dose response relationship between seasonal variations in occurrence and age. It may be speculated that younger people have more change to work outdoors, exposing themselves to the winter environment. Their lifestyle and physiological condition may be different from those of older people.

A comparison of socioeconomic differences in physical functioning and perceived health among male and female employees in Britain, Finland and Japan

We compared the pattern of socioeconomic inequalities in physical functioning and perceived health among male and female employees in Britain, Finland and Japan. Participants were male and female public sector employees in Britain, Finland and Japan, who were economically active and 40-60 year-olds at the time of data collection. We measured perceived health and physical functioning (SF-36 physical component summary) with standardized health questionnaires. The results obtained here reconfirm the similarity of the patterns of ill-health of those with lower socioeconomic status among non-manual men and women in Britain and Finland. These data also provide good evidence for a socioeconomic gradient in ill-health among Japanese non-manual men, although this gradient was less systematic. For Japanese men poorer health of manual workers as compared to non-manual workers was well demonstrated. However, among Japanese women socioeconomic differences in health were small and inconsistent. In conclusion, Britain, Finland and Japan--representing 'liberal', 'Nordic' and 'conservative' welfare state regimes--produce broadly similar patterns of socioeconomic differences in health among men. However, different patterns of labour force participation and welfare provision in different welfare regimes may bring about different patterns of socioeconomic differences in health for working women. This is exemplified by the lack of health inequalities among employed Japanese women.

TET2 is essential for survival and hematopoietic stem cell homeostasis

Ten-Eleven-Translocation 2 (TET2) is an enzyme that catalyzes the conversion of 5-methylcytosine into 5-hydroxymethylcytosine (5-hmC) and thereby alters the epigenetic state of DNA; somatic loss-of-function mutations of TET2 are frequently observed in patients with diverse myeloid malignancies. To study the function of TET2 in vivo, we analyzed Ayu17-449 (TET2(trap)) mice, in which a gene trap insertion in intron 2 of TET2 reduces TET2 mRNA levels to about 20% of that found in wild-type (WT) mice. TET2(trap/trap) mice were born at Mendelian frequency but died at a high rate by postnatal day 3, indicating the essential role of TET2 for survival. Loss of TET2 results in an increase in the number of hematopoietic stem cells (HSCs)/progenitors in the fetal liver, and TET2(trap/trap) HSCs exhibit an increased self-renewal ability in vivo. In competitive transplantation assays, TET2(trap/trap) HSCs possess a competitive growth advantage over WT HSCs. These data indicate that TET2 has a critical role in survival and HSC homeostasis.