Biomedical subjects

E J Nelson

Publications and source records attributed to E J Nelson.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Extended survival of neocytes produced by a new system.

Red cells (RBCs) prepared by a new system using centrifugation to produce neocyte enrichment were studied in two laboratories. The system used a blood bag with a geometric configuration such that younger, less dense cells could be separated from older, denser cells. Phthalate ester density gradient curves determined that neocyte enrichment was 81.3 percent in one laboratory and 82 percent in the other. RBC viability was studied by 51Cr autologous transfusion in normal volunteer donors. A randomized, paired design was used in which each donor was transfused once each with neocytes and with RBCs of all ages. The mean control half-life was 34.8 +/- 5.4 days in one laboratory and 34.0 +/- 3.6 days in the other. The mean half-life of the neocyte-enriched RBCs was 45.2 +/- 8.2 days in one laboratory and 45.1 +/- 4.4 days in the other. This represented a more than 30 percent increase in half-life for the neocyte-enriched RBCs, a significant difference. This new system, a two-bag set that costs +15, allows the simple, efficient separation of neocyte-enriched RBCs that would have a longer half-life and could reduce the transfusion requirement in patients receiving chronic transfusion therapy.

Blood Transfusion↗

PubMedDate not supplied

Preparation of white cell-depleted red cells for 42-day storage using an integral in-line filter.

A new blood pack system for the preparation of white cell-depleted red cells was studied. The system is a modified additive-solution quadruple-unit blood pack that incorporates a cellulose-acetate fiber depth filter in-line between the AS-3 additive bag and the CP2D collection bag. Mean +/- SD white cell removal from 156 units processed under standard production conditions was 97.7 +/- 2.7 percent; residual white cells were 1.1 +/- 1.0 x 10(8) per unit. Red cell loss was 10.0 +/- 1.0 percent (n = 43). Mean platelet removal was 80.9 percent from units from which platelet concentrates were not prepared (n = 47). Microaggregates did not form during storage, and hemolysis of filtered red cells was lower than that of unfiltered controls. Filtered AS-3 red cells stored for 42 days had a 51Cr survival of 80.1 +/- 5.7 percent (mean +/- SD) as compared with 78.9 +/- 6.2 percent for unfiltered controls (n = 17). This in-line filter system provides white cell-depleted, microaggregate-free red cells that can be stored for 42 days.

Adenosine Triphosphate↗

PubMedDate not supplied

Visual identification of bacterially contaminated red cells.

There have been increasing numbers of reports of transfusion-acquired Yersinia enterocolitica bacteremia (including several fatal cases). Fifteen units of whole blood were inoculated with various concentrations of Y. enterocolitica serotype 0:3 and processed into AS-3 preserved red cells (RBCs). Consistent growth of the organism was found at inoculum concentrations greater than or equal to 10 colony-forming units per mL. In all 13 units of RBCs that supported the growth of Y. enterocolitica, a darkening in color (due to hemolysis and a decrease in pO2) was observed in the bag. The attached sample segments, which were sealed from the main unit, remained sterile and did not darken. This color change was apparent in all the contaminated units by Day 35, which was 1.5 to 2 weeks after the bacteria were first detected in cultures of the blood. Hence, by comparison of the color of the segment tubing with that of the unit itself, units grossly contaminated with Y. enterocolitica can be identified prior to transfusion. Moreover, review of photographs on file at the Centers for Disease Control revealed this dramatic color change in 2 units of blood that caused transfusion-transmitted sepsis (Enterobacter agglomerans and an unidentified gram-negative bacillus, not Yersinia sp.), which demonstrated that the color change was not limited to Y. enterocolitica. This method of visual identification of contaminated units of blood could decrease the incidence of posttransfusion bacterial sepsis.

Color↗

PubMedDate not supplied

pH changes caused by bacterial growth in contaminated platelet concentrates.

While platelet concentrates are stored at room temperature, lactic and other acids are produced and the pH decreases as the buffering capacity of the plasma is exhausted. Platelet viability will be compromised if the pH decreases to pH 6.0 and below. Similarly, a pH decrease can be produced also by bacterial contamination if the organisms produce acid as an end product. Thus the determination of pH could serve as a sensitive indicator of bacterial contamination. This hypothesis was tested by us by inoculating known organisms into platelet concentrations. It was found that the pH may decrease, may remain unchanged, or, in a few cases, even increase. Visual signs of contamination could be observed but not consistently enough to be entirely dependable. Therefore, this method does not appear to detect bacterial contamination reliably in platelet concentrates.

Bacteria↗