Calibration of the superconducting gravimeter CT#043 with an absolute gravimeter FG5#210 at Syowa Station, Antarctica

For the purpose of calibration of the superconducting gravimeter (SG) model CT#043 at Syowa Station, Antarctica, we carried out parallel observations with the absolute gravimeter (AG) FG5#210. Although the AG measurements were conducted from December 31, 2003 to February 9, 2004, SG measurements before January 17 are found to have suffered artificial sensitivity change. We finally adopted data from January 17 to February 1, 2004, and obtained the scale factor of CT#043 as -59.461 ±0.079μGal/volt by linear regression analysis. The result achieved a relative accuracy of around 0.1%, which is important to modern precise tidal analysis. We also determined the scale factor by comparing the data of parallel observations with the SG TT70#016. Both values showed good agreement, supporting the reliability of the above mentioned value

Trends of preterm birth and low birth weight in Japan: a one hospital-based study

Background: The proportions of preterm birth (PTB, ie., delivered before 37 gestational weeks) and low birth weight (LBW, ie., birth weight less than 2500 g at delivery) have been rising in developed countries. We sought to examine the factors contributing to the rise in Japan, with particular focus on the effects of obstetric interventions. Methods: We used a database maintained by one large regional hospital in Shizuoka, Japan. We restricted the analysis to mothers who delivered live singleton births from 1997 to 2010 (n = 19,221). We assessed the temporal trends in PTB and LBW, then divided the study period into four intervals and compared the proportions of PTB and LBW. We also compared the newborns’ outcomes between the intervals. Results: PTB, in particular medically indicated PTB, increased considerably. The increase was largely explained by changes in caesarean sections. The neonatal outcomes did not worsen, and instead the Apgar scores and proportions requiring neonatal intensive care unit (NICU) admission improved. In particular, the risks of NICU admission in the interval from 2007 to 2010 were decreased among all births [odds ratio (OR): 0.84; 95% confidence interval (CI): 0.75, 0.95] and medically indicated births (OR: 0.44; 95% CI: 0.29, 0.68) compared with the interval from 1997 to 2000. Conclusions: Despite the increases in PTB as well as LBW, the present study suggests benefits of obstetric interventions. Rather than simple categorization of PTB or LBW, indicators such as perinatal mortality or other outcomes may be more appropriate for evaluation of perinatal health in developed countries

Early-term birth and hypoglycaemia

Background : The effect of early-term birth on the development of hypoglycaemia in large-for gestational-age (LGA) neonates is yet to be clarified. This study aimed to clarify the association between hypoglycaemia and early-term birth in LGA neonates. Methods : This single-centre retrospective cohort study evaluated LGA neonates born at term at Tsurugi Municipal Handa Hospital, Japan. Blood glucose levels were measured immediately and at 1, 2, and 4 hours after birth. The association between early-term birth and hypoglycaemia was evaluated using logistic regression analysis. The prevalence of severe hypoglycaemia and hypoglycaemia according to its timing of development was analysed using Fisher’s exact test. Results : In total, 295 neonates were included. Among them, 113 neonates (38.3%) were born at early term and 91 infants (30.8%) had hypoglycaemia. Logistic regression analysis showed a significant association between early-term birth and hypoglycaemia (adjusted odds ratio [95% confidence interval] : 2.691 [1.597 to 4.535]). However, there was no significant between-group difference among those with severe hypoglycaemia. Conclusions : Among LGA neonates, early-term birth is positively associated with neonatal hypoglycaemia. This indicates that among LGA neonates, those born at early term require more careful observation for hypoglycaemia than do those born at later term

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平成24年(2012)12月21日(金)及び22日(土)に、平城宮跡資料館講堂において開催した

Long-term exposure to methylmercury and psychiatric symptoms in residents of Minamata, Japan

Introduction: It is well-known that prenatal or postnatal exposure to methylmercury can produce neurological signs in adults and children, exemplified by a case of large-scale poisoning in Minamata, Japan, in the 1950s. However, evidence regarding whether pre- or postnatal exposure to methylmercury causes psychiatric symptoms (e.g., impairment of intelligence and mood and behavioral dysfunction) is still limited-excluding cases of fetal Minamata disease patients. Methods: We evaluated the effects of pre- or postnatal exposure to methylmercury on psychiatric symptoms using data derived from a 1971 population-based survey in Minamata and neighboring communities. We adopted residential areas as an exposure indicator and psychiatric symptoms as the outcome. Then, we estimated the adjusted prevalence odds ratio (POR) and confidence interval (Cl) of psychiatric symptoms in relation to residential area. Results: There were 904 participants in Minamata (high exposure area), 1700 in Goshonoura (middle exposure area), and 913 in Ariake (low exposure area). Compared to the Ariake area, participants in the Minamata area manifested psychiatric symptoms more frequently: PORs for impairment of intelligence and mood and behavioral dysfunction were 5.2 (95% Cl: 3.7-7.3) and 4.4 (95% Cl: 2.9-6.7), respectively. Furthermore, participants with psychiatric symptoms in the Minamata area more frequently had neurological signs. Peaks in prevalence of psychiatric symptoms occurred around age 20 and in older age adults in the area. These findings did not change when we excluded those who had been officially certified as Minamata disease patients by that time. Conclusions: The present study suggests a relationship between pre- or postnatal exposure to methylmercury and psychiatric symptoms among the general population in Minamata even after excluding officially certified patients