Peter J. Hmel

Stored packed red blood cells contain a procoagulant phospholipid reducible by leukodepletion filters and washing

BACKGROUND Ageing RBC gradually increase the exposure of phosphatidylserine (PS) on their surface, due to loss of membrane asymmetry. PS expression on red cells is not normally a significant factor in the hemostatic process, because aged RBC are rapidly cleared from the circulation. We propose that the presence of many altered red cells during massive transfusion can lead to increased procoagulant activity similar to what is seen in disease states where it is known to play a pathophysiologic role in microvascular disease. STUDY DESIGN AND METHODS Procoagulant activity of phospholipid generated during storage of PRBC was evaluated using PRBCs as the only source of phospholipid in the determination of modified Russells viper venom times of 10 PRBC units in which half of each unit was left unfiltered and half of each unit filtered. Florescent labeled annexin V binding by PRBC was also assessed by flow cytometry over time in storage. The effect of washing and filtration on these parameters was also determined. RESULTS As time of storage increased, the Russells viper venom time of both the unfiltered and filtered units shortened (p<0.01). There was a significant lengthening of the Russells viper venom time at all time points measured when unfiltered units were compared to filtered units (p<0.01). In both unfiltered and filtered units, with increased length of storage, there was a gradual increase in the percentage of cells or particles binding annexin V (p<0.01). Filtration resulted in a significant reduction in the percentage of cells or particles binding annexin V at all time points measured (p<0.01). The effect of washing of PRBC units on the RVVT was assessed for unfiltered and filtered units on day 42. Washing resulted in a significant reduction of the RVVT in both unfiltered and filtered groups (p<0.01). CONCLUSIONS Levels of annexin V binding and procoagulant phospholipid activity similar to levels seen in disease states associated with significant vasoocclusive pathophysiology were found toward the end of the storage period of PRBC units. It was possible to reduce both of these parameters by leukodepletion at collection, and with washing of PRBC at the end of storage. Filtration at collection resulted in a 67% increase in RVVT over unfiltered units by day 42 of storage. On day 42 of storage, washing of filtered units resulted in a 21% increase in RVVT, and washing of unfiltered units resulted in a 34% increase in RVVT. The effects seen with filtration and washing were additive suggesting that in spite of filtration at collection, deterioration of cells continues based on age since further removal of phospholipid can be induced with washing of filtered units on day 42.

New insulation technology provides next-generation containers for “iceless” and lightweight transport of RBCs at 1 to 10°C in extreme temperatures for over 78 hours

BACKGROUND: There is a universal need, in both civilian and military settings, for a lightweight container capable of maintaining RBCs at 1 to 10°C in remote areas, during extended transit times, and under austere environments. The use of ice in insulated containers or small commercial coolers for these purposes often results in loss of RBCs due to failure to maintain temperatures within the requisite range. A lightweight and thermally efficient container capable of carrying 4 to 6 units of RBCs at 1 to 10°C for over 72 hours under extreme conditions would help resolve current problems in RBC transportation.

Physical and thermal properties of blood storage bags: implications for shipping frozen components on dry ice.

BACKGROUND: Frozen blood components are shipped on dry ice. The lower temperature (–70°C in contrast to usual storage at –30°C) and shipping conditions may cause a rent in the storage bag, breaking sterility and rendering the unit useless. The rate of loss can reach 50 to 80 percent. To identify those bags with lower probability of breaking during shipment, the thermal and physical properties of blood storage bags were examined.

CHARACTERIZATION OF THE MAIN PHASE TRANSITION IN 1,2-DIPALMITOYL-PHOSPHATIDYLCHOLINE LUVS BY 1H NMR*

ABSTRACT The main phase transition (Tm) of 100 nm large unilamellar vesicles (LUVs) of 1,2-dipalmitoylphosphatidylcholine (DPPC) was investigated using 1H NMR (proton magnetic resonance) in deuterium oxide, and both DSC (differential scanning calorimetry) and IR (infrared) spectroscopy in water and deuterium oxide. The ability of 1H NMR to determine Tm was demonstrated and the values obtained were in general agreement with those observed with DSC and IR. However, the temperature range of the transition observed by NMR was significantly broader than that observed with either DSC or IR. The effect of deuterium oxide on Tm was studied by comparing results obtained in water and deuterium oxide with DSC and IR. The results showed no significant difference in Tm or temperature range of transition determined in these solvents.

White particulate matter found in blood collection bags consist of platelets and leukocytes

BACKGROUND:  In late January 2003, some blood centers and hospitals throughout the US voluntarily sus‐pended the use of some RBC and plasma units for trans‐fusion due to the presence of unknown white particulate matter (WPM) in these units. To better understand the WPM phenomena, a number of technologies were used to establish the nature of the particulates observed in Terumo Collection sets.

The Interaction of DMSO with Model Membranes. II. Direct Evidence of DMSO Binding to Membranes: An NMR Study

Abstract Modern techniques in nuclear magnetic resonance (NMR) allow investigators to probe molecular interactions with greater sensitivity and speed than ever before. Exploiting the nuclear Overhauser effect (NOE), the intermolecular interactions between dimethylsulfoxide (DMSO) and lipid vesicles were investigated. The DMSO methyl proton signal varies with experimental mixing time suggesting the system behaves in a manner similar to that of a ligand weakly binding to a macromolecule.

The Interaction of DMSO with Model Membranes. I. Comparison of DMSO and d6-DMSO: A DSC and IR Investigation

Abstract The effect of deuterated solvents on the main phase transition (Tm) temperature of large unilamellar vesicles (LUVs) of 1,2-dipalmitoyl phosphatidylcholine (DPPC) was examined by infrared spectroscopy and differential scanning calorimetry. There was no significant difference in the Tm, ΔH of the main transition, or cooperativity when water was replaced by deuterium oxide (D2O) in the preparation of the vesicles or when dimethylsulfoxide (DMSO) was replaced by hexadeutero-dimethylsulfoxide (d6-DMSO) in either D2O or water. These results provide the necessary advance for further structural, kinetic, and thermodynamic investigations of DMSO interactions with membranes and lipid vesicles.

Safety and efficacy of cryopreserved platelets in bleeding patients with thrombocytopenia: SAFETY OF CRYOPRESERVED PLTs

The short dating period of room temperature–stored platelets (PLTs; 5‐7 days) limits their availability at far‐forward combat facilities and at remote civilian sites in the United States. PLT cryopreservation in 6% DMSO and storage for up to 2 years may improve timely availability for bleeding patients.

The association of dimethylsulfoxide and model membranes studied by pulse-field gradient NMR

The use of dimethylsulfoxide (DMSO) as a cryoprotectant to reduce cellular injury during freezing is well known, however the intermolecular interactions between this amphiphilic molecule and biological membranes that form the basis of this protection are unknown. DMSO–dipalmitoylphosphatidylcholine (DPPC) vesicle interactions were investigated in pulsed-field gradient NMR (PFGNMR) experiments and spectra analysis allowed for the determination of self-diffusion coefficients for each species present. The mole fraction of DMSO associated with the DPPC vesicles was then calculated from the diffusion coefficients: the mole fraction increased from 14% to 42% as the membrane was heated from below to above the main phase transition temperature.