The effect of exclusion of cases with unrecorded best estimate of gestational age on the estimates of preterm birth rate

Objectives  To investigate the effect of excluding cases with unrecorded best estimate of gestational age at birth on pregnancy outcome reporting and to determine the reasons for unrecorded gestational age data.
Design  Prospective study.
Setting  Fifteen maternity units in North West London.
Population  497 105 women who booked for antenatal care from 1988 to 1998.
Method  Multiple logistic regression analysis.
Main outcome measures  Preterm birth rate of, and the factors associated with, cases with unrecorded best estimate of gestational age at birth.
Results  Of the 53 981 cases with an unrecorded best estimate of gestational age at birth, by using additional data, it was possible to compute a new best estimate of gestational age in 80%. In this latter group, the preterm birth rate was 42% (95% CI 41.5–42.6). The corrected, overall preterm birth rate in North West London (9.8%, 9.7–9.9) was higher than the original estimate (7.6%, 7.5–7.7), which included only cases with recorded data on gestational age at birth. The most significant factors associated with an unrecorded gestational age were no ultrasound scan (OR 49, P  <   0.001), and preterm birth <31 weeks (OR 30, P  <   0.001).
Conclusions  The incidence of preterm birth are likely to be under-reported in studies where only cases with readily available gestational age data are included. In routinely collected maternity data, human omission is an important contributing factor for an unrecorded best estimate of gestational age at birth. This is associated with the urgent transfer of babies to the neonatal intensive care unit.     

Total knee replacement in a patient with unsuspected tabes dorsalis

Rapid and progressive ligamentous laxity following an initially successful total knee replacement is unique in the authors' experience. One case is reported due to previously unsuspected tabes dorsalis.     

Dystroglycan is essential for early embryonic development: disruption of Reichert's membrane in Dag1-null mice

Dystroglycan is a central component of the dystrophin-glycoprotein complex (DGC), a protein assembly that plays a critical role in a variety of muscular dystrophies. In order to better understand the function of dystroglycan in development and disease, we have generated a null allele of dystroglycan (Dag1neo2) in mice. Heterozygous Dag1neo2 mice are viable and fertile. In contrast, homozygous Dag1neo2 embryos exhibit gross developmental abnormalities beginning around 6.5 days of gestation. Analysis of the mutant phenotype indicates that an early defect in the development of homozygous Dag1neo2 embryos is a disruption of Reichert's membrane, an extra-embryonic basement membrane. Consistent with the functional defects observed in Reichert's membrane, dystroglycan protein is localized in apposition to this structure in normal egg cylinder stage embryos. We also show that the localization of two critical structural elements of Reichert's membrane- -laminin and collagen IV--are specifically disrupted in the homozygous Dag1neo2 embryos. Taken together, the data indicate that dystroglycan is required for the development of Reichert's membrane. Furthermore, these results suggest that disruption of basement membrane organization might be a common feature of muscular dystrophies linked to the DGC.      

Accountability assessment of regulatory impacts on ozone and PM<Subscript>2.5</Subscript> concentrations using statistical and deterministic pollutant sensitivities

Since the 1990 Clean Air Act Amendments, the USA has seen dramatic decreases in air pollutant emissions from a wide variety of source sectors, which have led to changes in pollutant concentrations: both up and down. Multiple stakeholders, including policy-makers, industry, and public health professionals, seek to quantify the benefits of regulations on air pollution and public health, a major focus of air pollution accountability research. Two methods, one empirical, the other based on a chemical transport model (CTM), are used to calculate the sensitivities of ozone (O₃) and particulate matter with diameters less than 2.5 μ m (PM_2.5) to electricity-generating unit (EGU) and mobile source emissions. Both methods are applied to determine impacts of controls on daily concentrations (which are important in assessing acute health responses to air pollution), accounting for nonlinear, meteorologically, and emission-dependent responses of pollutant concentrations. The statistical method separates contributions of nearby EGU, regional EGU, and mobile source emissions on ambient city-center concentrations. Counterfactual emissions, an estimate of emissions under a scenario where no new controls were implemented on local EGU sources after 1995, regional EGUs after 1997, and mobile sources after 1993, are combined with these sensitivities to estimate counterfactual concentrations that represent what daily air quality in Atlanta, GA would have been had controls not been implemented and other emissions-reducing actions not been taken. Regulatory programs are linked with reduced peak summertime O₃, but have had little effect on annual median concentrations at the city-center monitoring site, and led to increases in pollutant levels under less photochemically-active conditions. The empirical method and the CTM method found similar relationships between ozone concentrations and ozone sensitivity to anthropogenic emissions. Compared to the counterfactual between 2010 and 2013, the number of days on which O₃ (PM_2.5) concentrations exceeded 60 p p b (12.0 μ g m ^?3) was reduced from 396 to 200 (1391 to 222). In 2013, average daily ambient O₃ and PM_2.5 concentrations were reduced by 1.0 p p b (2 %) and 9.9 μ g m ^?3 (48 %), respectively, and fourth highest maximum daily average 8-h O₃ was reduced by 14 p p b. Comparison of model-derived sensitivities to those derived using empirical methods show coherence, but some important differences, such as the O₃ concentration where the sensitivity to NO_x emissions changes sign.