Single-stranded DNA oligonucleotides (ODNs) can be used to direct the exchange of nucleotides in the genome of mammalian cells in a process known as gene editing. Once refined, gene editing should become a viable option for gene therapy and molecular medicine. Gene editing is regulated by a number of DNA recombination and repair pathways whose natural activities often lead to single- and double-stranded DNA breaks. It has been previously shown that introduction of a phosphorotioated ODN, designed to direct a gene-editing event, into cells results in the activation of γH2AX, a well-recognized protein biomarker for double-stranded DNA breakage. Using a single copy, integrated mutant enhanced green fluorescent protein (eGFP) gene as our target, we now demonstrate that several types of ODNs, capable of directing gene editing, also activate the DNA damage response and the post-translational modification of proliferating cell nuclear antigen (PCNA), a signature modification of replication stress. We find that the gene editing reaction itself leads to transient DNA breakage, perhaps through replication fork collapse. Unmodified specific ODNs elicit a lesser degree of replication stress than their chemically modified counterparts, but are also less active in gene editing. Modified phosphothioate oligonucleotides (PTOs) are detrimental irrespective of the DNA sequence. Such collateral damage may prove problematic for proliferation of human cells genetically modified by gene editing.

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The perinatal periods of risk (PPOR) methodology provides an easy-to-use analytical approach to infant mortality that helps focus community initiatives for improving maternal and infant health. Because few analyses have been published, many public health practitioners may be unfamiliar with PPOR. This article demonstrates the application of PPOR analysis using infant mortality in Jackson County, Missouri. While the PPOR consists of two phases, this analysis was restricted to the initial phase of the overall process. The second phase builds on the initial findings and prioritizes the contributing factors of fetal/infant mortality so that targeted interventions can be developed. For Jackson County, the PPOR analysis found that racial and geographic disparities existed and, for very low-birth-weight infants, different interventions strategies may be needed on the basis of race. In addition, a mother who experienced a fetal or infant death was more likely to have had a medical risk factor, to have smoked cigarettes, to have started prenatal care after the first trimester or received no prenatal care, and to have been nulliparous.