Structural basis of nucleosome assembly by the Abo1 AAA+ ATPase histone chaperone

The fundamental unit of chromatin, the nucleosome, is an intricate structure that requires histone chaperones for assembly. ATAD2 AAA+???ATPases are a family of histone chaperones that regulate nucleosome density and chromatin dynamics. Here, we demonstrate that the fission yeast ATAD2 homolog, Abo1, deposits histone H3???H4 onto DNA in an ATP-hydrolysis-dependent manner by in vitro reconstitution and single-tethered DNA curtain assays. We present cryo-EM structures of an ATAD2 family ATPase to atomic resolution in three different nucleotide states, revealing unique structural features required for histone loading on DNA, and directly visualize the transitions of Abo1 from an asymmetric spiral (ATP-state) to a symmetric ring (ADP- and apo-states) using high-speed atomic force microscopy (HS-AFM). Furthermore, we find that the acidic pore of ATP-Abo1 binds a peptide substrate which is suggestive of a histone tail. Based on these results, we propose a model whereby Abo1 facilitates H3???H4 loading by utilizing ATP

The outcome of transobturator anterior vaginal wall prolapse repair using porcine dermis graft: intermediate term follow-up

Introduction and Hypothesis We evaluated the anatomical success and complications of Perigee® with porcine dermis Graft in the repair of anterior vaginal wall prolapse (AVWP) Materials and Methods After Institutional Review Board (IRB) approval, the charts of all patients who underwent AVWP repair using the Perigee/InteXen® kit from July 2005 to July 2009 were reviewed. Patients who had less than 6-month follow-up were excluded. Preoperative data including patient age, previous AVWP repairs, hysterectomy status, preoperative dyspareunia and pertinent physical findings were collected and recorded. Postoperative success was defined as anatomical stage 0 or I using the Pelvic Organ Prolapse Quantification (POP-Q) scoring system. Graft related complications were also recorded. Results Out of 89 patients, 69 completed at least 6-month follow-up. Median follow-up was 13 (6-48) months. Seventeen patients (25%) had previous AVWP repair and 32 (46%) had previous hysterectomy. Preoperatively, AVWP stage II was found in 9 (13%), stage III in 27 (39%) and stage IV in 33 (48%) patients. Anatomic success was found in 48 (69%) patients, with 23 (33%) having stage 0 and 25 (36%) stage I AVWP. Intraoperative complications included incidental cystotomy in one patient and bladder perforation in one. Postoperative complications included vaginal exposure and dyspareunia in one case, wound dehiscence in one and tenderness over the graft arm with dyspareunia in one. conclusions The use of porcine dermis in AVWP repair is safe with minimal graft related complications; however, anatomical success is lower than that reported with the use of synthetic grafts