The Optimal Cell Salvage Settings to Maximize Hematocrit and Minimize Potassium Using the Cobe BRAT2 Autologous Blood Recovery Unit.

OBJECTIVE: The objective was to determine the optimal cell saver device settings (infusion rate and wash rate) at which hematocrit is preserved and potassium and lactate are removed from banked red blood cells (RBC). DESIGN: Red cells were washed using the Cobe BRAT 2 Autologous Blood Recovery Unit and sampled for electrolyte composition and hematocrit pre- and postwash. SETTING: This was a single-center study. INTERVENTIONS: Red cells were washed using six infusion rates (100-1,000 mL/min) and six wash rates (100-1,000 mL/min) for a total of 36 combinations. Hematocrit, potassium, glucose, and lactate were evaluated before and after washing. MEASUREMENTS AND MAIN RESULTS: At wash rates ≤400 mL/min, hematocrit increased independent of infusion rate. At wash rates ≥400 mL/min, slower infusion rates were associated with higher hematocrit compared to faster infusion rates (p < 0.0001 for a wash rate 400-800 mL/min, p < 0.0005 for a wash rate 1,000 mL/min). Maximal wash speeds were associated with decreasing hematocrit. Infusion and wash rate were both independent predictors of potassium change; slower rates were associated with a larger decrease in potassium. Glucose decreased proportionally as infusion and wash rate decreased. Lactate did not show an association with either infusion or wash rate. CONCLUSION: Red-cell washing produces higher hematocrit and lower potassium as infusion rate and wash rate decrease. A 340-mL unit of RBC can be processed in 4.26 minutes without loss of hematocrit or an increase in potassium when both infusion and wash rates are set to 400 mL/min.

A model for sealing plasmalemmal damage in neurons and other eukaryotic cells.

Plasmalemmal repair is necessary for survival of damaged eukaryotic cells. Ca(2+) influx through plasmalemmal disruptions activates calpain, vesicle accumulation at lesion sites, and membrane fusion proteins; Ca(2+) influx also initiates competing apoptotic pathways. Using the formation of a dye barrier (seal) to assess plasmalemmal repair, we now report that B104 hippocampal cells with neurites transected nearer (<50 µm) to the soma seal at a lower frequency and slower rate compared to cells with neurites transected farther (>50 µm) from the soma. Analogs of cAMP, including protein kinase A (PKA)-specific and Epac-specific cAMP, each increase the frequency and rate of sealing and can even initiate sealing in the absence of Ca(2+) influx at both transection distances. Furthermore, Epac activates a cAMP-dependent, PKA-independent, pathway involved in plasmalemmal sealing. The frequency and rate of plasmalemmal sealing are decreased by a small molecule inhibitor of PKA targeted to its catalytic subunit (KT5720), a peptide inhibitor targeted to its regulatory subunits (PKI), an inhibitor of a novel PKC (an nPKCη pseudosubstrate fragment), and an antioxidant (melatonin). Given these and other data, we propose a model for redundant parallel pathways of Ca(2+)-dependent plasmalemmal sealing of injured neurons mediated in part by nPKCs, cytosolic oxidation, and cAMP activation of PKA and Epac. We also propose that the evolutionary origin of these pathways and substances was to repair plasmalemmal damage in eukaryotic cells. Greater understanding of vesicle interactions, proteins, and pathways involved in plasmalemmal sealing should suggest novel neuroprotective treatments for traumatic nerve injuries and neurodegenerative disorders.

Polyethylene glycol rapidly restores axonal integrity and improves the rate of motor behavior recovery after sciatic nerve crush injury.

The inability to rapidly (within minutes to hours) improve behavioral function after severance of peripheral nervous system axons is an ongoing clinical problem. We have previously reported that polyethylene glycol (PEG) can rapidly restore axonal integrity (PEG-fusion) between proximal and distal segments of cut- and crush-severed rat axons in vitro and in vivo. We now report that PEG-fusion not only reestablishes the integrity of crush-severed rat sciatic axons as measured by the restored conduction of compound action potentials (CAPs) and the intraaxonal diffusion of fluorescent dye across the lesion site, but also produces more rapid recovery of appropriate hindlimb motor behaviors. Improvement in recovery occurred during the first few postoperative weeks for the foot fault (FF) asymmetry test and between week 2 and week 3 for the Sciatic Functional Index (SFI) based on analysis of footprints. That is, the FF test was the more sensitive indicator of early behavioral recovery, showing significant postoperative improvement of motor behavior in PEG-treated animals at 24-48 h. In contrast, the SFI more sensitively measured longer-term postoperative behavioral recovery and deficits at 4-8 wk, perhaps reflecting the development of fine (distal) motor control. These and other data show that PEG-fusion not only rapidly restores physiological and morphological axonal continuity, but also more quickly improves behavioral recovery.