α-Tubulin Mutations Alter Oryzalin Affinity and Microtubule Assembly Properties To Confer Dinitroaniline Resistance ▿ †

Plant and protozoan microtubules are selectively sensitive to dinitroanilines, which do not disrupt vertebrate or fungal microtubules. Tetrahymena thermophila is an abundant source of dinitroaniline-sensitive tubulin, and we have modified the single T. thermophila α-tubulin gene to create strains that solely express mutant α-tubulin in functional dimers. Previous research identified multiple α-tubulin mutations that confer dinitroaniline resistance in the human parasite Toxoplasma gondii, and when two of these mutations (L136F and I252L) were introduced into T. thermophila, they conferred resistance in these free-living ciliates. Purified tubulin heterodimers composed of L136F or I252L α-tubulin display decreased affinity for the dinitroaniline oryzalin relative to wild-type T. thermophila tubulin. Moreover, the L136F substitution dramatically reduces the critical concentration for microtubule assembly relative to the properties of wild-type T. thermophila tubulin. Our data provide additional support for the proposed dinitroaniline binding site on α-tubulin and validate the use of T. thermophila for expression of genetically homogeneous populations of mutant tubulins for biochemical characterization

Acute management of hemodynamically unstable pelvic trauma patients: Time for a change? Multicenter review of recent practice

© Société Internationale de Chirurgie 2008Background: Hemorrhage-related mortality (HRM) associated with pelvic fractures continues to challenge trauma care. This study describes the management and outcome of hemodynamically unstable patients with a pelvic fracture, with emphasis on primary intervention for hemorrhage control and HRM. Methods: Blunt trauma patients [Injury Severity Score (ISS) ≥16] with a major pelvic fracture (Abbreviated Injury Score, pelvis ≥3) and hemodynamic instability [admission systolic blood pressure (SBP) ≤90 mmHg or receiving ≥6 units of packed red blood cells (PRBCs)/24 hours) were included into a 48-month (ending in December 2003) multicenter retrospective study of 11 major trauma centers. Data are presented as the mean ± SD. Results: A total of 217 patients (mean age 41 ± 19 years, 71% male, ISS 42 ± 16) were studied. The admission SBP was 96 ± 37 mmHg and the Glascow Coma Scale (GCS) 11 ± 5. Patients received 4 ± 2 liters of fluids including 4 ± 4 units of PRBCs in the emergency room (ER). In total, 69 (32%) patients died, among whom the HRM was 19%; 29% of the deaths were due to pelvic bleeding. Altogether, 120 of the 217 (55%) patients underwent focused abdominal sonography for trauma (FAST) or diagnostic peritoneal aspiration (DPA) and diagnostic peritoneal lavage (DPL); 60 of the 217 (28%) patients were found to have pelvic binding in the ER. In all, 53 of 109 (49%) patients had no bleeding noted at laparotomy, 26 of 106 (25%) had no abdominal findings, and 15 of 53 (28%) had had no prior abdominal investigation (FAST/DPL/computed tomography). Angiography was positive in 48 of 58 (83%) patients. The HRM was highest in patients with laparotomy as the primary intervention (29%) followed by the angiography group (18%), the combined laparotomy/pelvic fixation group (16%), and the pelvic fixation-only group (10%). Conclusion: HRM associated with major pelvic trauma is unacceptably high especially in the laparotomy group. Hence, nontherapeutic laparotomy must be avoided, concentrating instead on arresting pelvic hemorrhage. Standards of care must be implemented and abided by.Diederik Verbeek, Michael Sugrue, Zsolt Balogh, Danny Cass, Ian Civil, Ian Harris, Thomas Kossmann, Steve Leibman, Valerie Malka, Anthony Pohl, Sudhakar Rao, Martin Richardson, Michael Schuetz, Caesar Ursic and Vanessa Will