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Biomedical subjects

W H Dzik

Publications and source records attributed to W H Dzik.

At least 37 records · Page 2Linked to original sources
PubMed1996

Multicenter evaluation of the 3% paraformaldehyde method for white cell counting in leukocyte-reduced red blood cells. BEST (Biomedical Excellence for Safer Transfusion) Working Party of the International Society of Blood Transfusion.

BACKGROUND/AIM: The 3% paraformaldehyde (PFA) method is a simple technique for counting residual white blood cells (WBC) in leukocyte-depleted red blood cells (RBC). Preliminary data suggested that its sensitivity is at least equal to PCR and flow cytometry. We report the results of a multicenter study conducted by the BEST Working Party to determine precision and accuracy of the 3% PFA method. STUDY DESIGN: In the 7 participating laboratories, 5 sets of samples containing nominal concentrations of 200, 100, 50, and 10 WBC/ml were prepared by diluting whole blood into 'WBC-free' RBC. Ten milliliters of each sample were processed using the 3% PFA method, which is based on erythrocyte lysis and WBC concentration into 5% of the original sample volume; a Nageotte chamber is used to count concentrated WBC. RESULTS: The precision of the technique varied according to the nominal concentration, ranging from a CV of 12% at 200 WBC/ml to 57% at 10 WBC/ml. The technique measured fewer than the nominal WBC concentrations (mean of all laboratories, -12.4%); underestimation was probably due to cell loss during sample manipulation. Overall accuracy was however acceptable, because statistical considerations establish that the actual WBC concentration would unlikely exceed 2 times the estimated count. CONCLUSIONS: The 3% PFA method is suitable for the enumeration of residual WBC at concentrations > or = 50/ml. It represents a useful tool for evaluation of high performance filters by reference laboratories.

Cell Separation↗
PubMed1994

Effects on recipients of exposure to allogeneic donor leukocytes.

Blood transfusion recipients are exposed to allogeneic donor leukocytes at the time of transfusion. Exposure to allogeneic donor leukocytes has been linked to a variety of complications of transfusion including primary HLA alloimmunization and platelet refractoriness, febrile nonhemolytic transfusion reactions, transmission of leukotropic viruses, transfusion-associated graft versus host disease, and transfusion-induced immune suppression. The development of high-performance leukodepletion blood filters and of low-leukocyte plateletapheresis machines has provided the technology to reduce recipient exposure to allogeneic donor leukocytes. This article provides a brief review of current information on the utility and shortcomings of these technologies for the prevention of leukocyte-mediated transfusion complications.

Blood Donors↗
PubMed1994

Multicenter evaluation of methods for counting residual white cells in leukocyte-depleted red blood cells. The Biomedical Excellence for Safer Transfusion (BEST) Working Party of the International Society of Blood Transfusion.

Two wet workshops were conducted involving 20 laboratories to determine optimum methods for counting residual white blood cells (WBC) in leukocyte-depleted red blood cells (RBC). In both studies, calibration samples containing known concentrations of WBC were prepared by diluting 1-day-old EDTA blood in RBC virtually free of WBC. Study No. 1 was aimed at determining the lower limit of detection and at examining advantages and disadvantages of two methods based on flow cytometry (FC) and on the Nageotte chamber (NC), respectively. This study showed that the lower detection limits for FC and NC were 0.1 and 1 WBC/microliters, respectively. Methods based on FC showed less variability at 0.1-1 WBC/microliters but were equal in performance to counting procedures based on the NC above 1 WBC/microliters. We then designed study No. 2 to evaluate three different protocols using the NC. In protocol 1, samples were diluted 1:10 with Plaxan and with Türk's solution; in protocol 2 a mixture of Türk's solution and Zap-oglobin, a reagent used in manual hemoglobin determinations, was used to dilute the samples 1:5; and protocol 3 involved initial 1:10 dilution of a 1-ml sample with Plaxan followed by WBC concentration into the original 1-ml volume by centrifugation. In each participating laboratory, two technologists independently processed the samples and read the results with an NC. Plaxan and Türk's solution gave comparable results. Interobserver variability was not critical to the results. All three NC methods were valid for counting at concentrations of > or = 1 WBC/microliters.(ABSTRACT TRUNCATED AT 250 WORDS)

Calibration↗
PubMed1993

Large-volume hemocytometer chamber for accurate counting of white cells (WBCs) in WBC-reduced platelets: validation and application for quality control of WBC-reduced platelets prepared by apheresis and filtration.

A detailed description is provided of a method using a large-volume (50 microL) hemocytometer to count very low numbers of white cells (WBCs) in platelet components. A method employing a Nageotte hemocytometer uses crystal violet stain and a standard microscope with a reading time of 5 to 10 minutes. The method is validated by using serial dilutions of known concentrations of WBCs in platelets and by correlation with a flow cytometric technique. The interobserver coefficient of variation was 11.9 percent for WBC concentrations > 2 per microL. Use of the method for the evaluation of 203 WBC-reduced platelet components prepared by apheresis or by filtration revealed that over 94 percent of components had WBC content < 5 x 10(6). This method could easily be applied in the routine quality control of WBC-reduced platelet components and in clinical studies employing these components.

Blood Component Removal↗
PubMed1993

The effects of gamma irradiation versus white cell reduction on the mixed lymphocyte reaction.

The risk of transfusion-associated graft-versus-host disease (TA-GVHD) is related to the number of viable T cells transfused. Whether white cell (WBC)-reduced blood components would carry a decreased risk of TA-GVHD was considered, and the allogeneic mixed lymphocyte reaction was used as an in vitro model for TA-GVHD. An exponential decline in the mixed lymphocyte reaction was found to occur, as a result of either an arithmetic increase in the dose of gamma irradiation given to responding cells or a logarithmic decrease in the number of unirradiated responding cells. Irradiation of responding cells with 600 cGy or a 0.6 log10 reduction in the number of responding cells produced a 95-percent decline in the mixed lymphocyte reaction. Although these studies do not validate the use of WBC reduction as a substitute for gamma irradiation for the prevention of TA-GVHD, they suggest that the relative risk of TA-GVHD resulting from the use of standard cellular components versus WBC-reduced components merits further investigation.

Dose-Response Relationship, Radiation↗
PubMed1992

Safety and efficacy of autologous blood donation before elective aortic valve operation.

Although the use of preoperative autologous blood donations for patients undergoing elective cardiac operations has increased dramatically in recent years, patients awaiting elective aortic valve replacement have traditionally been denied access to preoperative autologous blood collection programs. We report our experience with 79 patients, each of whom donated 1 to 3 units of autologous blood before an aortic valve operation. All patients had serious aortic valve disease as evidenced by symptoms and preoperative catheterization data. The patients collectively made 129 blood donations. One patient had a syncopal episode within 2 hours of donation and recovered without difficulty. Of the patients who gave autologous blood preoperatively, 68% avoided any homologous blood donor exposure during their subsequent hospitalization for aortic valve replacement. In contrast, in a group of 298 patients who did not give autologous blood preoperatively, only 31% avoided homologous blood exposure during aortic valve replacement (p < 0.0001). Our experience suggests that preoperative autologous blood donation by patients awaiting elective aortic valve replacement is both safe and effective. Patients with aortic valve disease should not be routinely excluded from preoperative blood services.

Adult↗
PubMed1992

Reevaluation of current transfusion practices in patients in surgical intensive care units.

Widespread interest in the complications associated with packed red blood cell (PRBC) transfusions has led to the scrutiny of traditional transfusion practices. Recently, attempts have been made to define more clearly the indications for PRBC transfusions in patients, particularly those who are critically ill. At present, however, transfusions continue to be ordered based on a hemoglobin level less than 10 g/dL. We report herein the impact on oxygen consumption of PRBC transfusions administered for a hemoglobin concentration less than 10 g/dL in 30 surgical intensive care unit patients who were euvolemic and hemodynamically stable. For the group as a whole, transfusion had a negligible effect on oxygen consumption. Fifty-eight percent of all such transfusions failed to change oxygen consumption by greater than 10% and could therefore be considered of questionable benefit.

Adult↗
PubMed1992

The effect of prestorage white cell reduction on the function and viability of stored platelet concentrates.

The role of residual donor white cells (WBCs) in producing the storage lesion of platelets used for transfusion was studied. The effect of prestorage WBC reduction on in vitro and in vivo measurements of the quality of stored platelet concentrates (PCs) was examined by using a newly developed WBC-reduction filter capable of preparing PCs with a mean residual WBC concentration of less than 1 per microL. For in vitro studies, a triplet study design was used, in which WBC-reduced PCs were matched to standard PCs and to WBC-enriched PCs obtained from the same donor at the same phlebotomy. Twelve donors were studied. Prestorage WBC reduction resulted in a higher pH and pO2 and a lower pCO2 than in standard PCs. In accord with previous in vitro studies, a significant rise in plasma glycocalicin and lactate dehydrogenase was measured during storage, but the levels were not significantly different in WBC-reduced PCs and standard PCs. Platelet aggregation and ATP release in response to graded doses of thrombin was similar in WBC-reduced and standard PCs. In vivo recovery and survival studies were comparable in WBC-reduced and standard PCs. Although the residual donor WBC content of PCs has a significant impact on storage pH, pO2, and pCO2, prestorage WBC reduction does not affect platelet structure, function, or viability as assessed by in vitro or in vivo measurements.

Adenosine Triphosphate↗
PubMed1992

Molecular biology of red cell blood group genes.

The explosion of new information and technology for probing the fine architecture of gene structure has already brought new insights into the varied phenotypic expression of red cell blood group antigens. Molecular biologic techniques will be increasingly applied to red cell antigens as well as blood group antigens on other blood cells. Not since the introduction of the Coombs reagent has such a powerful method been available with which to increase our understanding of the nature of blood cell antigens.

Amino Acid Sequence↗
PubMed1991

The preparation of platelet concentrates by the light-spin/hard-spin technique.

For at least two decades the light-spin/hard-spin (LS/HS) method for preparation of platelet concentrates (PC) has been the standard of platelet support. With concern over the detrimental effects of platelet activation during component preparation and with increased recognition of the adverse consequences resulting from residual donor leukocytes in PC, new approaches to the production of PC have begun. This review addresses two aspects of the traditional LS/HS method of platelet preparation: platelet activation and residual leukocyte content. Studies of platelet activation are reviewed which focus on the second (hard-spin) centrifugation step during which pelleting of platelets occurs. Platelets studied immediately after the hard-spin exhibit evidence of alpha-granule release, expression of activation antigens, and decreased aggregation. There is a suggestion that some degree of reversal of platelet activation routinely occurs during the rest period following the hard-spin. The residual leukocyte content of PC prepared by the LS/HS method ranges from 10 7 to 10 9 leukocytes/unit. The residual donor leukocytes are predominantly lymphocytes and monocytes. Degeneration of residual donor leukocytes may release soluble cytokines resulting in febrile transfusion reactions. It remains controversial whether or not the cell-membrane fragments and microvesicles of degenerating donor leukocytes are capable of HLA allosensitization or viral transmission. Release of leukocyte elastase from degenerating leukocytes during platelet storage has been proposed as contributing to the platelet storage lesion. More research is needed to address the question of whether or not pre-storage leukocyte reduction during component preparation will result in improved PC. It appears likely that within the next few years radical changes will occur in the method of preparation of PC with the aim of providing the greatest degree of hemostatic effectiveness with the least toxicity to patients.

Blood Component Transfusion↗
PubMed1991

Serologic and DNA follow-up data from HBsAg-positive patients treated with orthotopic liver transplantation.

Fifteen hepatitis B surface antigen (HBsAg) positive patients treated with orthotopic liver transplantation were studied to determine whether any clinical, serologic, or histologic data were predictive for recurrent hepatitis B infection leading to graft failure. Six patients died early, one due to primary graft nonfunction and the remaining five due to septic complications. There were nine patients surviving longer than two months, eight of whom are alive at a mean follow-up of 556 days. HBsAg and hepatitis B core antibody (anti-HBc) reappeared in the sera of all survivors after a variable transient period of clearance. One patient died 3 months posttransplant of fungal sepsis and was found to have histologic evidence for recurrent hepatitis and positive immunoperoxidase staining postmortem. The remaining eight survivors are home and clinically well, with no histologic evidence of hepatitis. Seven of these eight patients have hepatitis B viral DNA in their sera. We conclude that while there is a high early mortality, usually from sepsis, none of the serologic, histologic, or DNA data analyzed can be used to predict graft loss from recurrent hepatitis. No grafts have been lost due to recurrent hepatitis B in this series, and therefore we believe that HBsAg positive patients should not be excluded from transplantation.

Adult↗