In this study, we evaluated the efficacy of virtual microscopy as the primary mode of laboratory instruction in undergraduate level clinical hematology teaching. Distance education (DE) has become a popular option for expanding education and optimizing expenses but continues to be controversial. The challenge of delivering an equitable curriculum to distant locations along with the need to preserve our slide collection directed our effort to digitize the slide sets used in our teaching laboratories. Students enrolled at two performance sites were randomly assigned to either traditional microscopy (TM) or virtual microscopy (VM) instruction. The VM group performed significantly better than the TM group. We anticipate that this approach will play a central role in the distributed delivery of hematology through distance education as new programs are initiated to address workforce shortage needs.
Platelet antibodies identified in the plasma of three multiply transfused patients and a woman who had delivered a baby with neonatal alloimmune thrombocytopenia were investigated for their platelet activating properties. Three patients possessed multispecific HLA antibodies reactive with 90 to 100% of the cells on a lymphocytotoxic panel. These antibodies were also detected using the MAIPA assay and MAb w6/32, which recognizes an epitope common to all HLA class I molecules. In addition to HLA antibodies, three of the patients possessed platelet-specific antibodies that were identified by the MAIPA assay as anti-HPA-1a and anti-HPA-3a (one patient) and anti-HPA-1b (two patients). Each of the HLA antibodies when reacted with platelets expressing the corresponding HLA antigens, potently induced aggregation and release of ATP from dense granules. In contrast, the HPA-1b antibodies induced platelet agglutination, but failed to trigger ATP release. However, platelets coated with these latter antibodies were now refractory to subsequent stimulation by ADP. Similarly, when HLA antibodies were reacted with platelets to produce suboptimal activation, the platelets could now be stimulated only poorly or not at all by either epinephrine or thrombin. This was also true for anti-HPA-1b, which, although not inducing aggregation or ATP release by itself, was capable of almost completely blocking thrombin-induced platelet activation. The thrombin-inhibiting activity of these antibodies could partially be reversed by pretreating antibody-coated platelets with epinephrine immediately followed by stimulation with thrombin. These findings suggest that transfused platelets may either be activated or inhibited by reaction with various platelet antibodies. Therefore it is conceivable that the presence of platelet reactive antibodies in multiply transfused recipients may contribute to the increased thrombotic and hemorrhagic symptoms often observed among these patients.
Hemostasis laboratory testing methods have changed significantly over the past decades, from totally manual, to fully automated methodologies. Most medical laboratory educators prefer to use manual or semiautomated methods to teach hemostasis so that students can "see" what is occurring during the testing method, but many semi-automated instruments are no longer commercially available or are not cost-effective for education programs. In consideration of these factors and due to programmatic expansion to a coordinate campus, the CLS program explored new ways to teach hemostasis methods equitably and affordably across two distant locations. Working with an instructional design team versed in online education, five virtual hemostasis laboratory exercises were created that mimic the manual methodologies. Web-based didactic instruction was also developed to teach the testing theory and pathophysiology related to patient results. The efficacy of the virtual instruction was evaluated through assessment of student performance on exam questions, professional certification scores for the platelet/hemostasis sub-category, student satisfaction surveys, and evaluation of student performance during their clinical experience. Results showed that students in the virtual delivery format performed significantly better on exam questions compared to the traditional delivery method group, but there was no significant difference in their performance on the professional certification exam. Both student and preceptor feedback have been positive on the value of the exercises for students' understanding of hemostasis. ABBREVIATIONS
Profound thrombocytopenia accompanied by a severe coagulopathy developed in an elderly female patient being treated with cefotetan while undergoing surgery for closure of a perforated gastric ulcer. During the acute phase of the bleeding diathesis, the patient had a platelet count of 12 x 10(9)/l, a prothrombin time of 88 s (normal 10.0-11.8 s) and a PTT of 105 s (normal 23.0-37.0 s). Potent IgG cefotetan-dependent anti-platelet antibodies, which also were weakly reactive with ampicillin, were detected in the patient's serum using immunofluorescence and a recently developed protein A-agarose rosette forming assay. Unlike typical cephalosporin- and penicillin-induced antibodies that react with cells pretreated with drug, this antibody only reacted with platelets in the presence of exogenous drug. Failure of the antibody to react with drug-coated platelets suggests the possibility that, in this patient, sensitization to cefotetan involved mechanisms other than formation of typical hapten-carrier complexes normally described for members of the cephalosporin family of antibiotics. This appears to be the first definitive report that cefotetan, or any other cephalosporin derivative, can induce immunologic thrombocytopenia.
Three anti-Factor-VIII antibodies from hemophiliacs were reacted with samples of batches of Maws commerical bovine and porcine Factor VIII concentrates manufactured over a 12-year period. The apparent antibody concentrations varied widely with the different batches of concentrates. The variations are probably due to intrinsic differences in the antigenic nature of the Factor VIII in the different preparations. With the older porcine concentrates, the low apparent concentrations may be in part due to the reaction of antibody with inactive Factor VIII. When animal Factor VIII concentrates are used in treating hemophiliac patients who have anti-Factor-VIII antibodies, the least reactive batch should be chosen. Random batches of animal concentrates are not suited as a standard for measuring anti-Factor-VIII antibody concentration.
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