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S Wendel

Publications and source records attributed to S Wendel.

At least 19 recordsLinked to original sources
PubMed2002

Section 1B: Rh flow cytometry. Coordinator's report. Rhesus index and antigen density: an analysis of the reproducibility of flow cytometric determination.

Fifty-seven IgG monoclonal anti-D antibodies were evaluated in the Rh flow cytometry section, in which 12 laboratories participated. Staining protocols and a fluorescein (FITC)-conjugated Fab fragment goat anti-human IgG (H + L) as a secondary antibody were recommended but not mandatory. A CcDEe red blood cell (RBC) sample that was shown to be homozygous for RHD by molecular methods was supplied and used as internal 'standard RBC' throughout all experiments. An RBC panel comprising two partial D and four weak D types was supplied as well. The use of standard RBC reduced the variability of the data among the laboratories and allowed the conversion of fluorescence data into epitope densities, which were compounded in an antigen density (antigen D per RBC). The highest antigen density was determined for DVI type III, followed by DVII and weak D type 3; the lowest antigen density were determined for weak D type 1 and type 2. Nine of the 12 participating laboratories discriminated three groups of aberrant RhD that had similar Rhesus indices (RI): D category VI with RI = 0; weak D type 2 and type 3 with an high RI; and D category VII and weak D type 1 with an intermediate RI. The antigen densities and the Rhesus indices obtained correlated well among the laboratories of this Workshop section despite different staining protocols, secondary antibodies and instrumentation.

Algorithms↗
PubMed2002

A single window-period donation detected by human immunodeficiency virus p24 antigen after 5 years of routine screening in a group of Brazilian blood banks.

BACKGROUND AND OBJECTIVES: The purpose of this article was to describe the experience of screening for human immunodeficiency virus (HIV) p24 antigen (p24Ag) in blood donors, in four Brazilian Blood Banks, and to report the detection of the first window-period donation. MATERIALS AND METHODS: During 61 months (May 96 to June 01), 103 470 consecutive donations were screened for HIV p24Ag using commercially available enzyme-linked immunosorbent assay (ELISA) kits. Testing was carried out in accordance with the instructions supplied with the kits. RESULTS: Fifty-eight repeatedly reactive samples were identified [0.056% of the total; 95% confidence interval (95% CI): 0.042-0.070]. Ten of the 58 were confirmed as p24Ag positive after neutralization (0.010%; 95% CI: 0.004-0.016), nine of the 10 (0.009%; 95% CI: 0.003-0.014) were also HIV antibody positive and only one (0.001%; 95% CI: 0-0.003) was HIV antibody negative. CONCLUSIONS: In this setting the rate of sole p24Ag-positive donations was one in 103 740. This figure corresponds closely with the previously estimated yield of one in 87 796 donations. The yield of HIV p24Ag+ : Ab- has been previously estimated in our centres to be 1 : 87 796 donations, a value similar to that observed in actual practice.

Blood Banks↗
PubMed2000

Serologic testing for Trypanosoma cruzi: comparison of radioimmunoprecipitation assay with commercially available indirect immunofluorescence assay, indirect hemagglutination assay, and enzyme-linked immunosorbent assay kits.

The radioimmunoprecipitation assay (RIPA) has been used as a confirmatory test in several ongoing and published studies of Trypanosoma cruzi in blood donors in the United States. Despite its use as a confirmatory test, few studies are available comparing RIPA to commercially available serologic test methods. Thus, we compared RIPA with two indirect hemagglutination assays (Biolab Diagnostica SA, São Paulo, Brazil; Hemagen Diagnostics, Inc., Waltham, Mass.) and four different enzyme-linked immunosorbent assays (Abbott Laboratories, Abbott Park, Ill.; Embrabio, São Paulo, Brazil; Organon Teknika, São Paulo, Brazil; and Gull Laboratories, Salt Lake City, Utah) using a panel of 220 serum specimens from Brazilian blood donors with a range of T. cruzi antibody titers as determined by indirect immunofluorescence assay (IFA). A titer of 1:20 was used as the baseline for seropositivity. All IFA-negative serum specimens (n = 19) were nonreactive on all tests. At a titer of 1:20 (n = 9), reactivity rates varied considerably among the tests, with only the RIPA and the Organon and Gull assays identifying reactive specimens. For specimens at a 1:40 titer (n = 35), most assays identified at least 32 of 35 (91%) specimens as reactive, but the Biolab assay only identified 24 (69%). At higher titers (1:80, n = 56; 1:160, n = 101) the assays were comparable, with the exception of the Biolab assay, demonstrating rates of agreement with IFA of >/=98%. Overall, when compared with several other test formats, RIPA demonstrated equivalent or superior rates of agreement with IFA-positive specimens across all titers examined. In particular, at titers of >1:40, the RIPA compared favorably with other test methods currently in use, supporting its application as a confirmatory test, particularly in a research setting.

Animals↗
PubMed2000

Medical errors.

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Capital Expenditures↗
PubMed1999

The absolute number of circulating CD34+ cells as the best predictor of peripheral hematopoietic stem cell yield.

Many controversies still exist about the timing of leukapheresis procedures for PBSC transplantation. Thirty-nine patients were followed daily by monitoring the absolute PB WBC count and CD34+ cell enumeration prior to apheresis. These determinations were compared with the apheresis cell content (nucleated cells and CD34+ cells yield). There was a highly significant correlation between PB CD34+ cells and apheresis CD34+ cell yield (r = 0.921, p < 0.001). A small but significant correlation was found between the PB WBC count and the apheresis nucleated cell content (r = 0.383, p < 0.001), but no correlation was found between PB WBC count and apheresis CD34+ cell yield (r = -0.065, p = 0.460). A target value of 20 x 10(6) CD34+ cells/L was determined to be the most reliable predictor to collect at least 1.0 x 10(6) CD34+ cells/kg in a single apheresis. Of the 39 patients, 20 could be followed after transplantation, and a good correlation was found for total number of CD34+ cells reinfused and platelet and neutrophil engraftment. No correlation was found for nucleated cells infused and engraftment. CD34+ cell determination is a better predictor than WBC count for timing leukapheresis and is thus recommended for monitoring the quality of the product.

Adolescent↗
PubMed1998

Transfusion-transmitted Chagas' disease.

Transfusion-transmitted Chagas' disease has been recognized since 1952. Until recently, no cases were reported outside of Latin America. However, emigration during the past 20 years expanded its transfusional geographic borders to North America. Trypanosoma cruzi-infected donors usually are asymptomatic, often for a lifetime. This situation complicates donor screening, particularly in regions where blood bank personnel are not familiar with the risk factors and natural history of this transfusion-transmitted infection. This review addresses the main aspects of epidemiology, risks of infection, clinical symptoms in donors and recipients, preventive measures, and blood donor screening to prevent transfusion-transmitted Chagas' disease.

Blood Donors↗
PubMed1998

Overeating, reversal theory, and weight cycling.

America's overweight problem is universally recognized and escalating, despite billions of dollars spent to combat it. For the past century, a unidimensional paradigm was predominantly used to correct the overweight problem by reducing calories through dieting. As a result of the profound failure of traditional diet programs, a phenomenon known as weight cycling was born. In this article, a multidimensional paradigm is emphasized to address weight cycling. Reversal theory extends a new theoretical basis that can account for unpleasant feelings, or tension stress, as a trigger of overeating in women who weight cycle. A case example demonstrates how reversal theory explains overeating as a response to high-tension stress. Results of two studies are presented, describing overweight and normal-weight women's reversal theory states during self-reported episodes of overeating and resisting overeating. The multidimensional paradigm calls for emotional overeating behaviors to be addressed in weight management.

Adult↗
PubMed1996

Evaluation of Rh monoclonal antibodies for flow cytometry tests.

As participants of the "III International Workshop on Monoclonal Antibodies against Human Red Blood Cells and Related Antigens", we tested 43 RH monoclonal antibodies by the flow cytometry technique. Besides the anti-D antibodies (not included in this paper), we tested the following antibodies: three (3) anti-C; one (1) anti-Cw; six (6) anti-c; eight (8) anti-E; three (3) anti-e; two (2) anti-G; one (1) anti-CcEe (total = 24 antibodies). These antibodies (from different lab sources) were tested against antigen positive cells (homozygous or heterozygous) and antigen negative cells. When available, some of them were tested against "rare" phenotypes like ryr, r' 'Gr, rGr, R2Rz. All the three anti-C tested, showed poor discrimination between positive and negative cells; from the six anti-c tested, only three had good results (Workshop n degree 18, 20, 21) with a superior performance of one of them (Workshop n degree 18). From the eight anti-E tested, we found two (Workshop n degree 139 and 153) with good performance; all the three anti-e were non reactive; the two anti-G failed to react with r'r red cells; the anti-Cw reacted better with R1wr cells than R1wR1; and the anti-CcEe antibody showed good results with all the phenotypes tested. From the 24 antibodies tested, we found six (25%) antibodies with a good performance.

Antibodies, Monoclonal↗