Search PubMed⌕ Search

Biomedical subjects

B Wenz

Publications and source records attributed to B Wenz.

At least 55 records · Page 3Linked to original sources
PubMed1985

The unwarranted use of replicate analysis in routine coagulation studies.

The need to assure the validity of semiautomated coagulation procedures by performing replicate determinations is assessed. Prothrombin times (PT) and activated partial thromboplastin times (aPTT) were run as duplicate assays using two different photo-optical detection systems. Sixty specimens with a broad range of PT and aPTT results were studied as aliquots of 80, 100, and 140 microL of plasma. A total of 1,440 studies were performed. No statistically significant differences were found among the data for complementary groups of assays. It is concluded that replicate analyses do not enhance the precision nor the accuracy of these coagulation studies. These factors are more controlled adequately by quality assurance procedures, including frequent calibration checks, the use of internal standards, and multilevel commercial controls.

Blood Coagulation Tests↗
PubMed1985

Changes in intracellular Mg adenosine triphosphate and ionized Mg2+ during blood storage: detection by 31P nuclear magnetic resonance spectroscopy.

31P nuclear magnetic resonance (NMR) spectroscopy was used to measure changes in intra-erythrocyte Mg adenosine triphosphate (MgATP) and free Mg2+ during blood storage at 4 degrees C in standard citrate preservation media. The extent of Mg2+ complexation of ATP and the concentration of free Mg2+ were measured from the Mg2+-dependent chemical shift differences, at 22 degrees C, between the P beta and P alpha resonances of intracellular ATP. This difference changed from 721.0 +/- 1.4 Hz (mean +/- SE) on the day of collection to 741.0 +/- 3.4 Hz after three to seven days and 774.0 +/- 2.8 Hz after 11 to 40 days storage in either acid-citrate-dextrose (ACD) or citrate-phosphate-dextrose-adenine (CPDA-1). Changes in intracellular pH, detected from shifts in the intracellular Pi resonance, averaged 0.27 units after 11 to 40 days of storage. These data indicate a sizable decrease in the extent of Mg2+ complexation of ATP, and a decrease by a factor of 2.6 in free Mg2+, during the shelf-life of blood stored in ACD or CPDA-1.

Adenosine Triphosphate↗
PubMed1982

Successful chemotherapy of transfusion babesiosis.

We describe babesiosis transmitted by transfusion. The infected blood donor was identified and a minimum period of infectivity of the donor's blood was established. We report a new modality for chemotherapy consisting of quinine plus clindamycin, and a new endemic focus for this zoonosis on Fire Island, New York. There are insufficient data to establish a reasonably safe period after which visitors and residents of Babesia-endemic foci can become blood donors. Screening of such persons by a rapid serologic test, such as the ELISA or immunofluorescent antibody tests, is suggested.

Adult↗
PubMed1982

Partial immunologic reconstitution of a patient with acquired agammaglobulinemia: a transient phenomenon accompanying therapeutic plasmapheresis.

A patient with acquired agammaglobulinemia was treated with plasmapheresis. The rationale for this procedure was based on the presence of a cytotoxic autoantibody with specificity for helper (TH2-) T lymphocytes. Plasmapheresis reduced the autoantibody concentration to undetectable levels, which resulted in an increase number of helper T cells. These T cells provided normal in vitro helper activity. Plasmapheresis did not correct a concomitant suppressor T-cell defect, and the clinical remission ended during the fifth month of exchange therapy.

Adolescent↗
PubMed1980

Preparation of granulocyte-poor red blood cells by microaggregate filtration: a simplified method to minimize febrile transfusion reactions.

A simple, effective method for removing granulocytes from stored blood is described. Microaggregate filtration removes approximately 95% of the granulocytes from blood which has been stored for 2 weeks, centrifuged and filtered. The mean number of remaining leukocytes is 8 +/- 3.7 x 10(8)/unit. The residual white cell population, which is composed almost entirely of lymphocytes, is substantially less than the average number of cells previously associated with febrile reactions. 45 patients were selected for the study. All had significant febrile transfusion reaction histories, and averaged one reaction for every 3.6 U of conventional red cell product transfused. Administration of 212 units of microaggregate filtered granulocyte poor red cells caused a 95% reduction in the incidence of fibrile reactions. The technique is inexpensive, easily incorporated into the routine of the clinical blood bank, and does not require "open-system' processing. These considerations make microaggregate filtration a logical first choice method for the preparation of granulocyte-poor red blood cells.

Blood↗
PubMed1979

Detection of hepatitis B surface antigen with the miniature centrifugal fast analyzer. A modified reversed passive hemagglutination procedure.

A modified reversed passive hemagglutination test for the detection of hepatitis B surface antigen HBsAg is described. Sera and reagent cells coated with antibody to HBsAg (anti-HBs) are loaded separately into the rotor of a miniature centrifugal fast analyzer. The rotor is centrifuged briefly to transfer the components into its cuvettes. After mixing, the suspensions are allowed to stand at room temperature for 30 min, following which the rotor is again centrifuged and the absorbance of each cuvette is monitored. Cells suspended in serum containing HBsAg leave the light path more rapidly than cells suspended in sera free of antigen. The magnitude of change in absorbance varies directly with the concentration of the antigen. In 45 sera tested by the conventional V-plate technique, findings were as follows: 21 positive, 19 false positive and 5 negative. The automated procedure unequivocally differentiated the 21 positives; results for the false positive and negative specimens were identical and clearly distinguishable from the positive results. The automated procedure enhances specificity, offers equivalent sensitivity, and results that are quantitative and objective.

Absorption↗
PubMed1979

Improved method for detecting hemagglutination by centrifugal analysis.

Centrifugal analysis can be used to detect hepatitis B surface antigen, antibody to rubella virus, and fibrin-related antigen. The procedure is performed with the same reagents used in conventional hemagglutination studies. Positive and negative reactions are distinguished by the rates of erythrocyte clearance in the centrifugal field (delta A/delta time); positive cells move more rapidly than negative cells, and this difference varies directly with the concentration of detectable antigen or antibody. This phenomenon is thought to be a result of the greater adhesion of negative cells to the cuvette's surface. Sensitivity and specificity are greater in the centrifugal analysis technique than in the more conventional hemagglutination tests. False-positive reactions are eliminated and the quantitative data are accurate and reproducible.

Antibodies↗
PubMed1977

The effect of thrombocytopenia on experimental arteriosclerotic lesion formation in rabbits. Smooth muscle cell proliferation and re-endothelialization.

This study was designed to investigate the mechanisms involved in fibromusculoelastic lesion formation produced by selective de-endothelialization by the intra-arterial balloon catheter technique in thrombocytopenic rabbits. Thrombocytopenia was induced and maintained for up to 30 days by daily injections fo highly specific sheep anti-rabbit platelet sera (APS). Evidence for re-endothelialization was obtained by i.v. Evans blue dye 30 min before sacrifice. Rabbits received daily injections of APS, which reduced the mean platelet count to 5,600/cm3; control animals received identically treated normal sheep sera on the same schedule, and had mean daily platelet counts of 363,000/cm3. Evaluation of intimal thickness was assessed by counting cell layers in semithin sections. Intimal thickening in aortae from rabbits treated with APS was strikingly suppressed, in contrast to those from normal sheep sera-treated animals which showed a mean intimal thickness of 18 cell layers within 28 days often after de-endothelialization. Re-endothelialization was not affected by APS treatment. These results indicate that the proliferation of smooth muscle cells is dramatically inhibited by reduction of platelets.

Animals↗
PubMed1975

Development of direct antiglobulin reaction accompanying alloimmunization in a patient with Rhd (D, category III) phenotype.

New examples of the Rhd (D, category III) red cell phenotype are described in three siblings. One of these individuals who had previously been transfused, received three units of Rho(D) positive blood several years later and developed a high titer anti-RhD antibody. This anamnestic response was associated with the development of an autoantibody which persisted for a period of at least 8 months. This observation represents another example of autoimmunization which has rarely been observed to accompnay alloimmunization.

Adult↗
PubMedDate not supplied

Eluate analysis of anti-Bg a associated renal allograft rejection.

Renal allograft rejection, following development of a positive indirect antiglobulin reaction, occurred in a multiply transfused recipient. Panel techniques confirmed both anti-Bga and anti-Kell antibodies. Recognition of the concordant antigenic specificity of the Bga and HL-A7 antigens led to an investigation of the potential role of this antibody in the rejection phenomenon. In the absence of serological cytotoxicity, a modified elution technique was used to directly obtain immunoglobulin from the rejected allograft. The eluate obtained displayed specificity for the Bga red blood cell antigen. The described technique affords an additional approach to the documentation of immunologically mediated graft rejection and obviates the limitations imposed by the absence of serological cytotoxicity. Emphasis is placed on the need for recognition of the relationship between red blood cell and HL-A antigens.

Adolescent↗