Elucidating functions of DP1 and DP2 subunits from the Thermococcus kodakarensis family D DNA polymerase.

DNA polymerase D (PolD), originally discovered in Pyrococcus furiosus, has no sequence homology with any other DNA polymerase family. Genes encoding PolD are found in most of archaea, except for those archaea in the Crenarchaeota phylum. PolD is composed of two proteins: DP1 and DP2. To date, the 3D structure of the PolD heteromeric complex is yet to be determined. In this study, we established a method that prepared highly purified PolD from Thermococcus kodakarensis, and purified DP1 and DP2 proteins formed a stable complex in solution. An intrinsically disordered region was identified in the N-terminal region of DP1, but the static light scattering analysis provided a reasonable molecular weight of DP1. In addition, PolD forms as a complex of DP1 and DP2 in a 1:1 ratio. Electron microscope single particle analysis supported this composition of PolD. Both proteins play an important role in DNA synthesis activity and in 3'-5' degradation activity. DP1 has extremely low affinity for DNA, while DP2 is mainly responsible for DNA binding. Our work will provide insight and the means to further understand PolD structure and the molecular mechanism of this archaea-specific DNA polymerase.

Longitudinal Changes in Arterial Stiffness Associated with Physical Activity Intensity: The Toon Health Study.

AIMS: Several studies have revealed an association between moderate-to-vigorous physical activity (MVPA) and arterial stiffness, which is a known risk factor for cardiovascular disease. However, a few studies have considered the difference in the longitudinal effect of its intensity in a large general population. Therefore, we examined the effect of MVPA intensity on longitudinal changes in arterial stiffness. METHODS: We conducted a prospective cohort study involving 1,982 Japanese men and women. Arterial stiffness was measured using the cardio-ankle vascular index (CAVI) at baseline and 5-year follow-up. Physical activity was quantified using the Japan Arteriosclerosis Longitudinal Study Physical Activity Questionnaire and categorized into quartiles as MVPA levels. Linear mixed models were used to examine the differences at baseline and the rate of changes in CAVI associated with MVPA levels for over 5 years. RESULTS: The multivariable-adjusted mean differences in CAVI at baseline were significantly lower in the third (ß=-0.019 [95% confidence interval {CI}=-0.033 to -0.005]) and fourth (ß=-0.018 [95% CI=-0.035 to -0.001]) quartiles of the MVPA group compared with those in the lowest quartile of MVPA, and the significant effect persisted 5 years later. CONCLUSIONS: In summary, this study provides evidence to support the existence of a threshold for beneficial levels of MVPA in the prevention of arterial stiffness. Furthermore, this study suggests that exceeding this threshold may exert similar effects on arterial stiffness. These findings suggest that an optimal level of MVPA exists for preventing arterial stiffness, and exceeding this threshold may not engender additional benefits.

Decreased psychomotor vigilance is a risk factor for motor vehicle crashes irrespective of subjective daytime sleepiness: the Toon Health Study.

STUDY OBJECTIVES: Although excessive daytime sleepiness (EDS) has a crucial impact on motor vehicle crashes (MVCs), the assessment of subjective sleepiness as a screening tool for MVC has limitations. Objective daytime sleepiness may be a better predictor of MVCs rather than subjective daytime sleepiness. Therefore, we aimed to examine the association of psychomotor vigilance as a surrogate marker of objective sleepiness and subjective sleepiness with MVCs in a prospective cohort study of the general population. METHODS: The study participants were 903 community-dwelling Japanese followed up 5 years after baseline and ascertained history of MVC over the study period. Psychomotor vigilance was measured by the psychomotor vigilance test and categorized into quartiles by the reciprocal of the mean reaction time (mean1/RT). Subjective EDS was defined using the Japanese version of the Epworth Sleepiness Scale. Multivariable logistic regression analysis was used to examine the association between mean1/RT and MVC after stratification by subjective EDS. RESULTS: The multivariable-adjusted odds ratio (95% confidence interval) for MVC among the highest quartile group of mean1/RT was 0.31 (0.17-0.57), compared with the lowest group (P for trend < .01). After stratification by subjective EDS, the significant association was found only among the nonsubjective EDS group (P for trend < .01) and not among the subjective EDS group (P for trend = .16). CONCLUSIONS: Decreased psychomotor vigilance measured by the psychomotor vigilance test was associated with a higher risk of MVCs, and the association was more evident among the nonsubjective EDS group. The psychomotor vigilance test may be useful to prevent sleep-related MVCs in the general population, particularly for individuals without subjective EDS. CITATION: Matsuo R, Tanigawa T, Oshima A, et al. Decreased psychomotor vigilance is a risk factor for motor vehicle crashes irrespective of subjective daytime sleepiness: the Toon Health Study. J Clin Sleep Med. 2023;19(2):319-325.

Sleep disordered breathing and subjective excessive daytime sleepiness in relation to the risk of motor vehicle crash: the Toon Health Study.

Sleep disordered breathing (SDB) is a significant cause of motor vehicle crash (MVC). We conducted a prospective cohort study among 1047 Japanese community-dwellers to detect whether the presence or absence of subjective excessive daytime sleepiness (EDS) affect the association of SDB with a risk of MVC. SDB was assessed by a single airflow monitor which measured the respiratory disturbance index (RDI) during one-night, and participants were classified into the SDB group (RDI ≥ 10) and non-SDB group (RDI < 10). Subjective EDS was defined as Japanese version of Epworth Sleepiness Scale scores ≥ 11. A follow-up questionnaire five years after the baseline ascertained history of MVC over the period. Multivariable logistic regression analysis examined the association between SDB and MVC after stratification by subjective EDS. The multivariable-adjusted odds ratios (95% confidence interval) for MVC among the female SDB group were 1.66 (1.05-2.63) compared with the non-SDB group, and this association was more evident in females without subjective EDS [1.84(1.02-3.32)], but not among those with subjective EDS. There was no significant association in males. These findings indicate that SDB screening should be recommended regardless of subjective EDS to prevent SDB-related MVC among general population, particularly in females.