Bacillus subtilis RecO and SsbA are crucial for RecA-mediated recombinational DNA repair.

Genetic data have revealed that the absence of Bacillus subtilis RecO and one of the end-processing avenues (AddAB or RecJ) renders cells as sensitive to DNA damaging agents as the null recA, suggesting that both end-resection pathways require RecO for recombination. RecA, in the rATP·Mg(2+) bound form (RecA·ATP), is inactive to catalyze DNA recombination between linear double-stranded (ds) DNA and naked complementary circular single-stranded (ss) DNA. We showed that RecA·ATP could not nucleate and/or polymerize on SsbA·ssDNA or SsbB·ssDNA complexes. RecA·ATP nucleates and polymerizes on RecO·ssDNA·SsbA complexes more efficiently than on RecO·ssDNA·SsbB complexes. Limiting SsbA concentrations were sufficient to stimulate RecA·ATP assembly on the RecO·ssDNA·SsbB complexes. RecO and SsbA are necessary and sufficient to 'activate' RecA·ATP to catalyze DNA strand exchange, whereas the AddAB complex, RecO alone or in concert with SsbB was not sufficient. In presence of AddAB, RecO and SsbA are still necessary for efficient RecA·ATP-mediated three-strand exchange recombination. Based on genetic and biochemical data, we proposed that SsbA and RecO (or SsbA, RecO and RecR in vivo) are crucial for RecA activation for both, AddAB and RecJ-RecQ (RecS) recombinational repair pathways.

Episiotomía selectiva frente a episiotomía rutinaria en nulíparas con parto vaginal realizado por matronas / Selective episiotomy versus routine episiotomy in nuliparous women with vaginal delivery performed by midwives

Objetivo: Identificar las ventajas y desventajas en un grupo de mujeres a las que se ha practicado la episiotomía según un protocolo selectivo, con respecto a las que se les ha practicado episiotomía según un protocolo rutinario en los periodos de dilatación, parto, puerperio y a los tres meses del parto en nulíparas con parto vaginal realizado por matronas. Personas y método: Estudio prospectivo experimental, realizado en el Hospital Universitario Miguel Servet de Zaragoza, desde abril de 2004 a diciembre de 2005. Se incluyeron mujeres nulíparas, con feto único, a término y parto eutócico, en el grupo control (episiotomía rutinaria) o el grupo experimental (episiotomía selectiva) de forma aleatoria. Se recogieron variables en la dilatación, parto, puerperio inmediato y puerperio hospitalario mediante observación y entrevista, y a los tres meses posparto mediante entrevista telefónica. Resultados: Se han estudiado 402 mujeres, 202 del grupo control y 200 del grupo experimental. Se realizaron un 83,7% de episi omías en el grupo rutinario y un 59,0% en el grupo experimental. La duración de los periodos de dilatación y expulsivo fue similar en ambos grupos. La incidencia de desgarros posteriores de I y II grado fue superior en el grupo experimental (30%), frente al grupo control (13,4%) (p <0,001), pero no se presentó ningún caso de desgarros de III y IV grado. No se encontraron diferencias en los resultados perinatales, ni en el puerperio inmediato, pero en el puerperio hospitalario las mujeres del grupo control presentaron más dolor general, aunque leve, al sentarse, con la deambulación, y demandaron más analgésicos. A los tres meses del parto, destaca una mayor incidencia de dispareunia en mujeres con episiotomía (p <0,004). Conclusiones: La práctica de una política de episiotomía selectiva, por indicación fetal o materna, o periné poco distensible, en mujeres nulíparas a término, es segura (AU)

Objective: To identify the advantages and disadvantages in a group of women in whom episiotomy was performed according to a selective protocol as compared to those who underwent episiotomy according to a routine protocol, during the periods of dilatation, delivery and puerperium and three months after delivery in nulliparous women with vaginal delivery performed by midwives. Subjects and methods: A prospective, experimental study was carried out between April 2004 and December 2005 at Miguel Servet University Hospital in Zaragoza, Spain. Nulliparous women with full-term, singleton pregnancies and uncomplicated delivery were randomly assigned to the control group (routine episiotomy) or to the experimental group (selective episiotomy). The variables were assessed during dilatation, delivery, immediate puerperium and the remainder of the hospital stay by means of observation and interviews, and three months postpartum by means of telephone interviews. Results: A total of 402 women were studied, 202 in the control group and 200 in the experimental group. episiotomy was performed in 83.7% of the women in the routine group and in 59.0% of those in the experimental group. The duration of first and second stage was similar in the two groups. The incidence of subsequent first and second-degree lacerations was higher in the experimental group (30%) than in the control group (13,4%) (p <0.001), but there were no third or fourth-degree lacerations. There were no differences in the perinatal outcome or in the immediate puerperium, but, during the hospital stay, the women in the control group presented more general, although mild, pain when sitting down or walking, and requested greater amounts of analgesics. Three months after delivery, the incidence of dyspareunia was higher among women with episiotomy (p <0.004). Conclusions: It is safe to apply a policy of selective episiotomy in nulliparous women with a full-term pregnancy when indicated by fetal or maternal factors or when the distensibility of the perineum is limited (AU)