Anionic (i.e., acidic) phospholipids such as phosphotidylglycerol (PG) and cardiolipin (CL), participate in several cellular functions. Here we review intriguing in vitro and in vivo evidence that suggest emergent roles for acidic phospholipids in regulating DnaA protein-mediated initiation of Escherichia coli chromosomal replication. In vitro acidic phospholipids in a fluid bilayer promote the conversion of inactive ADP-DnaA to replicatively proficient ATP-DnaA, yet both PG and CL also can inhibit the DNA-binding activity of DnaA protein. We discuss how cellular acidic phospholipids may positively and negatively influence the initiation activity of DnaA protein to help assure chromosomal replication occurs once, but only once, per cell-cycle. Fluorescence microscopy has revealed that PG and CL exist in domains located at the cell poles and mid-cell, and several studies link membrane curvature with sub-cellular localization of various integral and peripheral membrane proteins. E. coli DnaA itself is found at the cell membrane and forms helical structures along the longitudinal axis of the cell. We propose that there is cross-talk between acidic phospholipids in the bacterial membrane and DnaA protein as a means to help control the spatial and temporal regulation of chromosomal replication in bacteria.

Several important anti-tumor agents form DNA interstrand crosslinks (ICLs), but their clinical efficiency is counteracted by multiple complex DNA repair pathways. All of these pathways require unhooking of the ICL from one strand of a DNA duplex by nucleases, followed by bypass of the unhooked ICL by translesion synthesis (TLS) polymerases. The structures of the unhooked ICLs remain unknown, yet the position of incisions and processing of the unhooked ICLs significantly influence the efficiency and fidelity of bypass by TLS polymerases. We have synthesized a panel of model unhooked nitrogen mustard ICLs to systematically investigate how the state of an unhooked ICL affects pol η activity. We find that duplex distortion induced by a crosslink plays a crucial role in translesion synthesis, and length of the duplex surrounding an unhooked ICL critically affects polymerase efficiency. We report the synthesis of a putative ICL repair intermediate that mimics the complete processing of an unhooked ICL to a single crosslinked nucleotide, and find that it provides only a minimal obstacle for DNA polymerases. Our results raise the possibility that, depending on the structure and extent of processing of an ICL, its bypass may not absolutely require TLS polymerases.

ObjectiveTo identify potential barriers to patient safety (PS) interventions from the perspective of surgical team members working in an operating theatre in Eastern Democratic Republic of Congo (DRC).DesignIn-depth interviews were conducted and analysed using qualitative content analysis.SettingGovernmental referral teaching hospital in Eastern DRC.ParticipantsWe purposively selected 2–4 national and expatriate surgical team members from each specialisation. Of the 31 eligible surgical health workers (HWs), 17 volunteered to be interviewed.ResultsEconomics issues affected PS throughout the entire health system, from human resources and hospital management, to access to healthcare for patients. Surgical team members seemed embedded in a paternalistic organisational structure and blame culture accompanied by perceived inefficient support services and low salaries. The armed conflict did not only worsen these system failures, it also carried direct threats to patients and HWs, and resulted in complex indirect consequences compromising PS. The increased corruption within health organisations, and population impoverishment and substance abuse among health staff adversely altered safe care. Simultaneously, HWs’ reported resilience and resourcefulness to address barrier to PS. Participants had varying views on external aid depending on its relevance.ConclusionsThe complex links between war and PS emphasise the importance of a comprehensive approach including occupational health to strengthen HWs' resilience, external clinical audits to limit corruption, and educational programmes in PS to support patient-centred care and address blame culture. Finally, improvement of equity in the health financing system seems essential to ensure access to healthcare and safe perioperative outcomes for all.

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Microstructural and electrical characterizations of air plasma sprayed TiO2 coatings were carried out to investigate the details of deoxidation during the spray process and the changes following air annealing. The coatings were found to behave as an n-type semiconductor indicating the presence of oxygen vacancies. Direct-current resistivity measurements in plane (ρIP) and through thickness (ρTT) of the coatings as a function of annealing time and temperature showed remarkably large anisotropies (=ρTT∕ρIP) of up to 105. Impedance spectroscopy of the specimens coupled with microstructural analysis revealed that the origin of this anisotropy lies in the heterogeneous deoxidation and reoxidation behavior of the coatings. Due to rapid quenching, the high temperature deoxidation state is preserved in the splat boundaries making them more conductive than the bulk of the splat in the as-sprayed coating. Upon annealing in air, the splat boundaries get selectively oxidized due to faster surface diffusion of oxygen and become more insulating. This behavior, together with the layered morphology of plasma sprayed coatings, results in anisotropy.