Variable frequency of polyomavirus SV40 and herpesvirus EBV in lymphomas from two different urban population groups in Houston, TX.

BACKGROUND: Studies have reported differing frequencies of detection of polyomavirus simian virus 40 (SV40) in association with human lymphomas. OBJECTIVE: We addressed the hypothesis that SV40 positivity in lymphomas can vary among sampled populations. STUDY DESIGN: Archival paraffin-embedded lymphoma specimens (n=171) from patients at two urban hospitals in Houston, TX, USA, were analyzed following a cross-sectional study design. Extracted DNAs were characterized by quantitative polymerase chain reaction for the cellular RNase P gene and for SV40 and herpesvirus Epstein-Barr virus (EBV) sequences. RESULTS: Patient characteristics of the two study populations differed significantly whereas the classification of tumor types studied did not. SV40 DNA was detected more frequently in lymphomas from the public hospital population (10/44, 23%) than in lymphomas from the veterans' hospital (VAMC) (4/127, 3%; P<0.0001). EBV detection in lymphomas also differed between the two groups (17/44, 39% vs. 23/127, 18%; P=0.01). SV40 positivity was associated with a younger age category of VAMC lymphoma patients (P=0.02). Expression of T-antigen was detected by immunohistochemistry in half of lymphomas that contained SV40 DNA. Variation was observed in the quality and quantity of DNA recovered from paraffin-embedded specimens, but there was no difference in recoveries of DNA from samples from the two hospitals. CONCLUSIONS: This study demonstrated that, in a direct comparison, the prevalence of SV40 DNA in lymphomas can differ significantly between groups with different demographic distributions.

Minimizing dilutional coagulopathy in exsanguinating hemorrhage: a computer simulation.

BACKGROUND: Current massive transfusion guidelines are derived from washout equations that may not apply to bleeding trauma patients. Our aim was to analyze these guidelines using a computer simulation. METHODS: A combined hemodilution and hemodynamic model of an exsanguinating patient was developed to calculate the changes in prothrombin time (PT), fibrinogen, and platelets with bleeding. The model was calibrated to data from 44 patients. Time intervals to subhemostatic values of each coagulation test were calculated for a range of replacement options. RESULTS: Prolongation of PT is the sentinel event of dilutional coagulopathy and occurs early in the operation. The key to preventing coagulopathy is plasma infusion before PT becomes subhemostatic. The optimal replacement ratios were 2:3 for plasma and 8:10 for platelets. Concurrent transfusion of plasma with blood is another effective strategy for minimizing coagulopathy. CONCLUSION: Existing protocols underestimate the dilution of clotting factors in severely bleeding patients. The model presents an innovative approach to optimizing component replacement in exsanguinating hemorrhage.