The frequencies of nonselected mutations among adaptive Lac؉ revertants of Escherichia coli strains with and without the error-prone DNA polymerase IV (Pol IV) were compared. This frequency was more than sevenfold lower in the Pol IV-defective strain than in the wild-type strain. Thus, the mutations that occur during hypermutation are due to Pol IV.
We sought to estimate the accuracy, relative to maternal medical records, of perinatal risk factors recorded on fetal death certificates. We conducted a validation study of fetal death certificates among women who experienced fetal deaths between 1996 and 2001. The number of previous births, established diabetes, chronic hypertension, maternal fever, performance of autopsy, anencephaly, and Down syndrome had very high accuracy, while placental cord conditions and other chromosomal abnormalities were reported inaccurately. Additional population-based studies are needed to identify strategies to improve fetal death certificate data.
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