1308. Ex vivo Impact of Autologous Blood Transfusion (ABT) on Concentrations of Antibiotics used for Surgical Prophylaxis

Abstract Background ABT is widely employed during surgical procedures involving high blood loss, such as liver transplantation and open heart surgery. While ABT mitigates the need for allogeneic blood transfusions, an unintended consequence may be removal of drugs, including antimicrobials. Herein, we determined the ex vivo loss of antimicrobials utilized for surgical prophylaxis through an ABT system. Methods Experiments were conducted in duplicate to simulate processing of ABT blood during surgery. Packed red blood cells and fresh frozen plasma (300ml) were acquired from banked blood and inoculated to achieve clinically-relevant plasma concentrations of vancomycin (VAN), the piperacillin (PIP) component of piperacillin/tazobactam, and the ampicillin (AMP) component of ampicillin/sulbactam. Inoculated blood was processed through a Cell Saver® Elite™ ABT system to fill a 125mL Latham bowl and washed with 500mL of normal saline. Processed fluid was directed to a reinfusion or waste bag; additional blood samples were collected from each. Drug concentrations were measured in all samples. The amount of VAN, PIP, and AMP infused through the Cell Saver (initial), and resulting in the reinfusion and waste bags was calculated. Results A range of 193-265mL of combined blood containing drug were processed in each experiment through the ABT system. Initial average plasma concentrations were 61, 107, and 172 mg/L for VAN, PIP, and AMP, respectively. When corrected for volume and hematocrit, plasma concentrations translated to a mean ± SD of 3 ± 1% of VAN in the reinfusion bag and 93 ± 2% in the waste bag. For PIP, plasma concentrations translated to 2 ± 1% of PIP in the reinfusion bag and 84 ± 13% in waste, while 2 ± 1% and 120 ± 5% of AMP was found in the reinfusion and waste bags, respectively. Unaccounted drug (0-14%) was considered sequestered in the device. Conclusion These ex vivo assessments of antibiotic removal during ABT are the first to demonstrate significant loss of antibiotics (&amp;gt;95%) when processed through the ABT system. Further studies measuring impact of ABT on drug concentrations in patients undergoing surgery are warranted. Disclosures David P. Nicolau, PharmD, Cepheid (Other Financial or Material Support, Consultant, speaker bureau member or has received research support.)Merck &amp; Co., Inc. (Consultant, Grant/Research Support, Speaker’s Bureau)Wockhardt (Grant/Research Support) Joseph L. Kuti, PharmD, Allergan (Speaker’s Bureau)bioMérieux (Research Grant or Support, Other Financial or Material Support, Speaker Honorarium)Melinta (Research Grant or Support)Merck &amp; Co., Inc. (Research Grant or Support)Paratek (Speaker’s Bureau)Summit (Other Financial or Material Support, Research funding (clinical trials)) </jats:sec

Contribution of Zinc-Dependent Delayed Calcium Influx via TRPC5 in Oxidative Neuronal Death and its Prevention by Novel TRPC Antagonist

Oxidative stress is a key mediator of neuronal death in acute brain injuries, such as epilepsy, trauma, and stroke. Although it is accompanied by diverse cellular changes, increases in levels of intracellular zinc ion (Zn2+) and calcium ion (Ca2+) may play a critical causative role in oxidative neuronal death. However, the mechanistic link between Zn2+ and Ca2+ dyshomeostasis in neurons during oxidative stress is not well-understood. Here, we show that the exposure of cortical neurons to H2O2 led to a zinc-triggered calcium influx, which resulted in neuronal death. The cyclin-dependent kinase inhibitor, NU6027, inhibited H2O2-induced Ca2+ increases and subsequent cell death in cortical neurons, without affecting the early increase in Zn2+. Therefore, we attempted to identify the zinc-regulated Ca2+ pathway that was inhibited by NU6027. The expression profile in cortical neurons identified transient receptor potential cation channel 5 (TRPC5) as a candidate that is known to involve in the generation of epileptiform burst firing and epileptic neuronal death (Phelan KD et al. 2012a; Phelan KD et al. 2013b). NU6027 inhibited basal and zinc-augmented TRPC5 currents in TRPC5-overexpressing HEK293 cells. Consistently, cortical neurons from TRPC5 knockout mice were highly resistant to H2O2-induced death. Moreover, NU6027 is neuroprotective in kainate-treated epileptic rats. Our results demonstrate that TRPC5 is a novel therapeutic target against oxidative neuronal injury in prolonged seizures and that NU6027 is a potent inhibitor of TRPC5