Automated blood-mixing devices still fail to mix at low bleeding rates.

BACKGROUND AND OBJECTIVES: The study evaluated mixing performance for various commercial blood-mixing devices at different flow rates. MATERIALS AND METHODS: A glycerol solution with a density equal to blood was pumped into a blood bag (mounted on a mixer) that contained 70 ml of Toluidin Blue in citrate-phosphate-dextrose (CPD). After 500 ml of glycerol solution had been pumped into the blood bag, the bag was emptied in fractions and the absorbance at 640 nm of each fraction (expressed as percentage of mixture absorbance) was plotted against the fraction number. RESULTS: At a flow rate of 30 ml/min, the curves were very sigmoid, with high initial values that decreased during collection of the fractions. The absorbance values of the fractions collected later (after approximately 250-300 ml) were 10-50% (i.e. percentage of absorbance for complete mixing) for the different mixers, indicating that the CPD solution was incompletely mixed with the incoming solution, resulting in a lower-than-expected 'anticoagulant' content for the fractions collected later. At a flow rate of 50 ml/min the mixing was improved, but only at 75 ml/min did all mixers show relatively good mixing. Manual mixing, by kneading the bag three times/min, gave at all rates an almost ideal mixing curve, 105% initially to 90% in the final fractions. CONCLUSION: At relatively high bleeding rates, all mixers performed well, although complete mixing was only obtained with manual kneading. However, most blood-mixing devices still fail to mix efficiently at normal and low bleeding rates. Although the minimal degree of necessary mixing is unknown, further optimization of mixing devices seems warranted.

Low leukocyte contamination without filtration by preparation of platelet concentrates in cylindrical bags with the buffy-coat method.

BACKGROUND AND OBJECTIVES: The buffy-coat (BC) method for platelet concentrate (PC) preparation was modified in order to obtain leukodepleted PCs from single BCs without filtration. MATERIALS AND METHODS: BCs were centrifuged in cylindrical BC bags and the optimal centrifugation conditions and optimal hematocrit were determined. RESULTS: With optimal conditions, a tenfold lower leukocyte contamination was obtained compared with the conventionally shaped, wide BC bag (0.3 +/- 0.19 versus 3.0 +/- 1.71 x 10(6) leukocytes per unit; 85-ml BCs). The platelet yield obtained with the cylindrical bag did not differ significantly from the yield obtained with the conventional bag (56 +/- 16.4 versus 61 +/- 15 x 10(9) platelets per PC). Furthermore, when PCs were prepared from 100-ml BCs in cylindrical bags, a leukocyte contamination of 0.2 +/- 0.11 x 10(6) and a platelet content of 61 +/- 13.5 x 10(9) per PC were obtained. CONCLUSION: The use of cylindrical BC bags reduced the leukocyte contamination in PCs to a level required for leuko-depletion without affecting platelet recovery.

Comparison between a new PVC platelet storage container (UPX80) and a polyolefin container.

During storage of platelet concentrates (PCs), the quality of the platelets deteriorates gradually, partially dependent on gas exchange. UPX80 (JMS, Japan) 1-L platelet storage PVC containers with increased gas transport capacity were compared with 1- and 1. 5-L polyolefin (PO) containers (NPBI, the Netherlands) with filtered PCs stored either in GAC (gluconate-acetate-citrate, < 10% plasma) or in plasma, for 8 days. In total 32 PCs were made (260-330 x 109 platelets per concentrate), equally divided over different bags and storage media. During storage, gas exchange, metabolic, physical and activation parameters were measured. No consistent differences for all parameters were observed between UPX80 and PO containers (1-L or 1.5-L). Blood gas parameters indicated better gas exchange for UPX80 containers compared with PO containers. Good morphology was observed in UPX80 and metabolic functions were not significantly different compared with PO containers. During prolonged storage (after day 6), some significant differences in CD62P and CD63 expression were found, indicating a higher degree of platelet activation in UPX80 containers, especially in GAC. UPX80 PC containers are suitable for storage of PCs. Although in UPX80 better gas exchange is demonstrated, as compared with PO containers, this does not improve the platelet quality during storage for 6 days, indicating that gas exchange above the level of PO containers has no effect on the switch to aerobic metabolism in platelets.

Pooled platelet concentrates prepared by the platelet-rich-plasma method and filtered with three different filters and stored for 8 days.

Pooled platelet concentrates (PC) prepared by the platelet-rich plasma (PRP) method were filtered with three different filters and stored for 8 days at room temperature. The effect of filtration on leukocyte contamination, platelet concentration, and the in vitro function, morphology, metabolism and activation of platelets were studied. Eight pools of 20 PRP-PC were used, each pool was split into 4 equal volumes; 3 were filtered over a PL50HF, a PL-10A and a Bio P10 filter, the 4 served as a control. After filtration, leukocyte counts exceeded 3 x 10(5) in none of the pooled PC. Platelet loss induced by filtration was about 17%. During storage, no differences in pH, PCO2, and lactate and glucose concentration were found between the filtered and the unfiltered units, nor were any differences observed between filtered and unfiltered pooled PC in aggregation upon stimulation with collagen and/or ADP, adhesion capacity to collagen in flowing blood, nucleotide content of the platelets and nucleobase concentration in the plasma, expression of activation-dependent antigens, or platelet morphology as observed by light microscopy and by the swirling effect. Selective removal of beta-thromboglobulin (22%) by the PL50HF filter was observed. Pooled PC prepared by the PRP-method can be filtered and stored for 8 days without detrimental effect on platelet function, metabolism or activation.

Stored platelets release nucleotides as inhibitors of platelet function.

It is well known that the function of platelets decreases progressively during storage of platelet concentrates at room temperature. To investigate this phenomenon in more detail, we have resuspended platelets that had been stored for 24 h or 72 h in fresh plasma, and we have measured the aggregation response and the ATP secretion. Conversely, the effect of plasma in which platelet concentrates (PC) had been stored for 24 h or 72 h, was tested on fresh platelets. Both the aggregation response to collagen and ADP and the collagen-induced ATP secretion of stored platelets partially recovered after incubation with fresh plasma (p < 0.05). The same parameters measured with fresh platelets incubated in stored PC-plasma were found to be significantly reduced in comparison with the response of fresh platelets in fresh plasma (p < 0.05). Finally, platelets were stored in a plasma-free medium, suitable for platelet storage and the supernatant was tested. This supernatant inhibited the function of fresh platelets in a storage time-dependent fashion. Boiling of these supernatants did not change the inhibiting capacities, whereas filtration over active charcoal did. Analysis of this supernatant revealed AMP and diadenosine tetraphosphate, which both inhibit platelet function. These data show that stored platelets release nucleotides that inhibit platelet function in a reversible manner. This phenomenon may contribute to the decrease of platelet function during storage and the recovery of platelet function after transfusion.

The effects of NaF, alpha-C12DMEAHF and alpha-C12DMEAHCl on caries development in dentine in situ.

Using histological techniques it was possible to demonstrate that during in situ caries development in bovine dentine, the demineralization process preceded the emergence and changes in the organic matrices. In addition, these data demonstrated as that 0.006% F- given either as the quaternary ammonium compound or NaF completely prevented demineralization by acting primarily on the dentine mineral. Inhibition by the quaternary ammonium compound alone was incomplete probably through repression of acid production by micro-organisms normally resident in the saliva.

In vitro evaluation of buffy-coat-derived platelet concentrates stored in a synthetic medium.

Human blood platelets, prepared by the buffy-coat method, were prepared and stored in different synthetic media. In a synthetic medium based on gluconate, acetate and citrate (GAC), the pH was 6.8 on day 6. This medium was chosen for further evaluation. The total platelet count and the leukocyte contamination were significantly lower in the platelet concentrates (PCs) prepared in GAC compared to PCs prepared in plasma. Platelets stored in plasma or in GAC were equally functional when tested for aggregation and adenosine triphosphate (ATP) secretion. Only stimuli that act through the arachidonic-acid pathway induced a lower platelet response in GAC. Platelet morphology was quantified by measuring the difference in light transmission during stirring at different rates in an aggregometer; no significant differences for platelets stored in GAC as compared to plasma were observed. Activation of platelets was measured by binding of monoclonal antibodies (McAb) against the Gp IIb/IIIa complex and against activation-dependent antigens (GMP 140 from the alpha-granules and a 53-kD glycoprotein from the lysosomal granules). There was no difference in binding of these McAb between platelets prepared and stored in plasma or GAC. We conclude that platelets prepared by the buffy-coat method and stored in GAC have the same in vitro qualities as platelets stored in plasma, except for the lower aggregation response by the arachidonic-acid pathway. This is probably due to an acetate-induced decrease in intracellular pH.