Asunto(s)
Rastreo Diferencial de Calorimetría/métodos , Dimetilsulfóxido/química , Liposomas/química , Espectrofotometría Infrarroja/métodos , Sitios de Unión , Unión Competitiva , Dimetilsulfóxido/metabolismo , Cinética , Ligandos , Metabolismo de los Lípidos , Lípidos/química , Liposomas/metabolismo , Espectroscopía de Resonancia Magnética/métodos , Tamaño de la Partícula , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Temperatura , Termodinámica , Agua/química , Agua/metabolismoRESUMEN
BACKGROUND: Frozen blood components are shipped on dry ice. The lower temperature (-70 degrees C in contrast to usual storage at -30 degrees 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. STUDY DESIGN AND METHODS: Blood storage bags were obtained from several manufacturers and were of the following compositions: PVC with citrate, di-2-ethylhexylphthalate (DEHP), or tri-2-ethylhexyl-tri-mellitate (TEHTM) plasticizer; polyolefin (PO); poly(ethylene-co-vinyl acetate) (EVA); or fluorinated polyethylene propylene (FEP). The glass transition temperature (Tg) of each storage bag was determined. Bag thickness and measures of material strength (tensile modulus [MT] and time to achieve 0.5 percent strain [T0.5%]) were evaluated. M(T) and T0.5% measurements were made at 25 and -70 degrees C. Response to applied force at -70 degrees C was measured using an impact testing device and a drop test. RESULTS: The Tg of the bags fell into two groups: 70 to 105 degrees C (PO, FEP) and -50 to -17 degrees C (PVC with plasticizer, EVA). Bag thickness ranged from 0.14 to 0.41 mm. Compared to other materials, the ratios of M(T) and T0.5% for PVC bags were increased (p < or = 0.001) indicating that structural changes for PVC were more pronounced upon cooling from 25 to -70 degrees C. Bags containing EVA were more shock resistant, resulting in the lowest rate of breakage (10% breakage) when compared with PO (60% breakage, p = 0.0573) or PVC (100% breakage, p = 0.0001). CONCLUSIONS: Blood storage bags made of EVA appear better suited for shipping frozen blood components on dry ice and are cost-effective replacements for PVC bags. For the identification of blood storage bags meeting specific storage requirements, physical and thermal analyses of blood storage bags may be useful and remove empiricism from the process.
Asunto(s)
Conservación de la Sangre/métodos , Embalaje de Productos/normas , Conservación de la Sangre/economía , Costos y Análisis de Costo , Criopreservación/métodos , Hielo Seco , Humanos , Ensayo de Materiales , Mecánica , Embalaje de Productos/economía , Temperatura , Resistencia a la Tracción , Transportes/métodosRESUMEN
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.