Search PubMed⌕ Search

Biomedical subjects

B Wenz

Publications and source records attributed to B Wenz.

67 records · Page 4Linked to original sources
PubMedDate not supplied

The preparation of leukocyte-poor red cells from liquid stored blood: an evaluation of the Haemonetics 102 cell washing system.

An evaluation of the Haemonetics 102, an automated cell washing system, is presented. Although the system removes 68.4 +/- 14 per cent of the white blood cells from liquid stored blood, the percentage wash out is an unreliable mode of evaluation. The residual number of white blood cells per unit is 6.5 +/- 2.8 x 10(8), which is independent of the unit's size, age, and initial leukocyte count. The residual number of white blood cells is also not influenced by any of the modifications used in the study. Red blood cell loss averaged 16.3 per cent. A direct correlation exists between the initial red blood cell mass and the amount of cell lost. It is recommended that packed cell units which have a volume of less than 300 ml with hematocrits of 75 per cent or less be used to minimize excessive red blood cell loss. Recommendation as to the selection of units by an ideal age or the preparation of units prior to washing are not supported by these data.

Blood Preservation↗
PubMedDate not supplied

The quality assurance of antiglobulin reactions with Fab-sensitized reagent red blood cells.

The production, function, and use of a new antiglobulin control cell is described. The cells are sensitized with monovalent Fab (fragment, antigen-binding) fragments and can be agglutinated by active antiglobulin serum only. In contrast to commercial antiglobulin control cells, which are frequently associated with false-positive results, the reactivity of the Fab-sensitized cells is entirely specific. It is concluded that Fab-sensitized cells provide greater quality assurance than currently available reagents.

Blood Group Incompatibility↗
PubMedDate not supplied

A mimicking red blood cell autoantibody accompanying transfusion and alloimmunization.

A patient with sickle cell disease who concomitantly developed red cell autoimmunity and alloimmunization is reported. The implied but 'wrong' specificity of the autoantibody mimicked one of the alloantibodies in the patient's serum. Although the patient's red blood cells phenotyped at Ro4, anti-rh" was eluted from them on several occasions. Absorption and secondary elution from selected cells proved the cell bound antibody had a unique and independent specificity from the anti-rh" in his serum. Standard antibody identification procedures did not distinguish these differences.

Anemia, Sickle Cell↗
PubMedDate not supplied

Serologic procedures performed in hydrophilized polystyrene cuvettes and borate glass tubes: a comparative study.

Serologic procedures were performed in parallel using hydrophilized polystyrene cuvettes and conventional glass test tubes. Consistent and comparable results were obtained with both containers. No significant differences in antibody titer, specificity, neutralization, or elution were observed. The effect of a proteolytic enzyme on red blood cell antigen was not altered by the hydrophilized plastic tubes. There was no difference in the stability of immune sera stored in glass or plastic at 4 degrees C and--30 degrees C. However, hemolysis of stored red blood cells was significantly slower in the hydrophilized plastic cuvettes.

Agglutinins↗
PubMedDate not supplied

Microaggregate blood filtration and the febrile transfusion reaction. A comparative study.

Seventy-four patients with chronic transfusion requirements and histories of repetitive febrile reactions were transfused with 1138 units of microaggregate-filtered red cells. The filtered blood was prepared using either a direct interception or a depth filter. One-half of the units were centrifuged immediately prior to filtration. Microaggregate filtration reduced the overall incidence of febrile transfusion reactions by 77 percent. The centrifugation-filtration protocol reduced the rate of reactions by 98 percent. There were no differences between the ability of the different filters to reduce the reaction rate; however, red cell loss was twice as large with the depth filter as with the direct interception filter. The numerical criterion for "leukocyte-poor blood" was met in all units processed by centrifugation-filtration. Only units processed during the last 2 weeks of shelf-life fulfilled this criterion when centrifugation was omitted from the procedure. The majority of the latter units were clinically tolerated well due to their reduced granulocyte content.

Cell Aggregation↗
PubMedDate not supplied

p Phenotype in an Ecuadorian family.

The red cell phenotype 'p' is reported in an Ecuadorian family of Spanish descent. There are no previous confirmed reports of Ecuadorian individuals with this rare allele. The proband was not the product of a consanguineous marriage. This factor together with certain geographical and historical considerations support speculation that there may be a small cohort of homozygous 'p' individuals in the region.

Adolescent↗
PubMedDate not supplied

The preparation of leukocyte-poor red cells for transfusion by a simple cost-effective technique.

A modification of the microaggregate filtration technique for the production of leukocyte-poor red cell concentrate is described. The modified technique, termed 'spin, cool, and filter', removed leukocytes more efficiently from relatively fresh blood than the original microaggregate filtration procedure. The residual leukocyte content of 4- to 9-day-old units processed by the modified procedure averaged less than 0.4 X 10(9) white cells per unit. The microaggregate filtration technique, supplemented by buffy-coat exclusion, removed more than 93 percent of the units' white cells. These red cell products were prepared easily and did not elicit febrile reactions in highly susceptible patients.

Blood Preservation↗
PubMedDate not supplied

Polyethylene glycol improves the indirect antiglobulin test.

PEG3350, a linear polymer of ethylene glycol, was evaluated as a potentiator of the indirect antiglobulin test (IAGT). The polymer enhances the avidity and affinity of clinically significant red cell alloantibodies than those obtained with bovine serum albumin (BSA). The sensitivity and specificity of the PEG-mediated reactions were superior to those obtained with BSA. Subpopulations of red cells, such as those encountered with fetomaternal hemorrhages, were detected at lower concentrations with PEG than with BSA using the microscopic Du test. The superiority of the PEG reaction, its simplicity, and the reagent's relatively low cost make substitution of the polymer for BSA in the IAGT an attractive option.

Antibody Affinity↗
PubMedDate not supplied

Phenotypic characterization of white cells in white cell-reduced red cell concentrate using flow cytometry.

The residual white cell (WBC) content of donated units of red cell concentrate rendered WBC-reduced by filtration through commercially available polyester filters was quantified and phenotypically analyzed. All studies were performed by flow cytometery. Quantification studies were performed with a DNA/RNA fluorophore, propidium iodide. WBC subset analyses were performed with fluorescence-labeled monoclonal antibodies directed against various cluster differentiation (CD) loci. The results indicate that the filter removes in excess of 3 log10 total WBCs from the red cell components and depletes granulocytes to or beyond the specific assay's sensitivity of 3 log10. Total T and B cells, T4 and T8 lymphocytes, and monocytes are reduced by approximately 4 log10. These analyses provide plausible explanations for the clinical success of the filter and suggest other potential applications.

Blood Component Removal↗
PubMedDate not supplied

Performance characteristics of state-of-the-art hematology analyzers.

Data were obtained from four state-of-the-art automated hematology analyzers and compared with those obtained from microscopic reference procedures. The instruments evaluated were the Technicon's H*1, Sysmex's NE-8000, Coulter's STKR, and Coulter's STKS. Accuracy was assessed by comparing machine-generated white blood cell and red blood cell profiles with those obtained manually by experienced laboratorians. Specimens used were actual clinical samples submitted for routine analysis. The precision of the instruments in counting and sizing blood cells was not significantly different at the clinical decision-making level and consistently exceeded that of the microscopic method. Significant shifts in the leukocyte population were detected with relatively similar sensitivity by all instruments. As expected, the oldest model's clinical efficiency was exceeded by that of the newer analyzers. None of the analyzers performed with an accuracy that permits the laboratory to completely eliminate a microscopic scan of a stained blood film obtained from a patient's initial specimen.

Equipment Design↗
PubMedDate not supplied

Detection of undiagnosed coagulopathies using routine rapid heparin neutralization.

OBJECTIVE: To determine the most frequent clinical causes of a prolonged activated partial thromboplastin time (APTT) result, and to determine whether a new heparin-removal device (the Hepchek, Pall Biomedical, Glen Cove, NY 11542) is capable of efficiently detecting the causes of these values. DESIGN: A combination of chart review and laboratory testing comparing the criterion standard--the heparin chromogenic substrate assay--with the Hepchek. Laboratory investigations were blinded and controlled. SETTING: Inpatient, acute-care hospital. PATIENTS: A total of 1,000 hospital patients with a variety of hemostatic disorders. MAIN OUTCOME MEASURE: The extent to which the Hepchek accurately identified the etiology of a prolonged APTT result. RESULTS: The APTT was prolonged in 25.2% of samples. The presence of heparin in the sample was confirmed by chromogenic assay or by using the Hepchek heparin-removal filter. The presence of heparin was confirmed in 12.8% of all samples and in more than 50% of all abnormal samples. The cause of the abnormal APTT was often unappreciated by the clinician. Bayesian analysis of the Hepchek's ability to diagnose heparin correctly as the cause of the abnormal APTT showed a sensitivity of 100% and specificity of 99.9%. CONCLUSION: Use of the Hepchek in the routine clinical laboratory is an efficient and rapid method of detecting heparin as a cause of isolated prolonged APTT results, and should reduce demands for unwarranted coagulation analyses and inappropriate treatment with blood products.

Bayes Theorem↗