A method based on dielectric properties of cellular suspensions was developed to study red blood cell (RBC) aggregability. The time-dependent current in a Couette-type viscometer was recorded after abrupt stoppage of shearing. Since the current reaches steady state 2 min after the end of shearing, the observed effects were quantified by the relative current difference, delta Irel = (I(2min)-I5s)/I2min, where subscripts designate the time of measurements. delta Irel increases with hematocrit, plasma and fibrinogen concentration. The dependence of delta Irel and of RBC aggregability on the concentration of dextran were similar. The experimental data and their analysis indicate that in suspensions with aggregating media, the delta Irel value measured in the field of the beta-dispersion reflects the difference between the size of aggregates under steady-state conditions and that of dispersed particles 5 s after the end of shearing. Therefore, this value may serve as a measure of RBC aggregability.

Blood Viscosity↗

PubMedDate not supplied

Changes in agglomeration of human red blood cells in liquid storage in CPD media.

A procedure which may distinguish between old and new CPD blood units in liquid state is described. It is based on the observation of increased tendency to reversible agglomeration in old erythrocytes in liquid preservation. Erythrocytes clump together when they are mixed with low ionic strength solutions in pH range of 5.2 to 6.5. We found that liquid-stored erythrocytes show an augmented tendency to agglomerate in 0.24M sucrose, pH 7.2. The tendency increases with storage so that in the fourth week, more than 70% of the units show agglomeration under these conditions. The addition of minute amounts of sodium chloride may prevent agglomeration. As the cells age, higher salt concentration is required to prevent agglomeration. A short incubation of washed cells with adenosine may reverse the tendency of outdated erythrocytes to agglomerate, concomitantly with reestablishment of initial ATP level. However, depletion of the ATP of fresh cells with fluoride does not induce agglomeration. A 20 hour incubation of units at 37 C with CPD revealed an increased sensitivity of older units, with low ATP and positive agglomeration. This test may help in distinguishing between outdated and younger units in the blood bank.

Adenosine↗

PubMedDate not supplied

The dependence of agglomeration of stored erythrocytes on fibrinogen and pH.

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Albumins↗

PubMedDate not supplied

Storage-induced changes in human newborn red cells.

Fetal red cells are well suited for intrauterine life; however, little is known about their response to postnatal environments. The purpose of this work was to investigate the metabolic and membrane changes affecting newborn red cells during their exposure to storage in citrate-phosphate-dextrose (CPD) and citrate-phosphate-dextrose-adenine (CPDA-1). The findings suggest that newborn red cells are affected more by storage than are adult cells. These accelerated storage changes in the red cells of newborns may be related indirectly to the rapid adenosine triphosphate (ATP) decline. As is the case with adult red cells, fetal cells withstand storage in CPDA-1 better than in CPD. The storage lesion in these cells was partly reversible, as in adult cells, by incubation with adenosine. It was therefore concluded that newborn red cells obtained from placentas and stored for several weeks in CPD or CPDA-1 media or other media that improve the metabolic profile of these cells may be acceptable for transfusion.

Adenosine↗

PubMedDate not supplied

Effect of oxidative stress on avian erythrocytes.

Avian erythrocytes differ from mammalian erythrocytes in being nucleated and oval. In the circulation, chicken cells survive for only 35 days, compared to 120 days for human cells. In humans, red cell oxidation processes, involving methemoglobin formation, have been correlated with cellular aging. This study compared oxidative resistance of two avian red cells (chicken and ostrich) to that of discoid enucleated human cells. Reduced glutathione levels (GSH) and methemoglobin were higher in chicken and ostrich cells than in human cells. SOD levels were higher in human cells. Diamide exposure diminished intracellular GSH levels in all species, with the greatest effect on human cells. Regeneration potential was high for all cells. Ostrich cells were more sensitive to hydrogen peroxide when hemoglobin oxidation was involved; BHP exposure affected GSH depletion and methemoglobin production in ostrich cells more than in the others. Lipid peroxidation was found to be highest in the human cells. Chicken cells were only slightly more resistant than human cells. Our data suggest that the extensive, complex oxidation by BHP cannot represent in vivo aging processes. In addition, the milder, selective oxidation by diamide affects human cells (endowed with long life span) more than avian cells. It is concluded that in vitro oxidation by diamide and BHP cannot be correlated with red cell survival.

Adult↗