Browsing by Autor "Sandro Villarroel"

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    First external quality assurance program for bloodstream Real-Time PCR monitoring of treatment response in clinical trials of Chagas disease
    (Public Library of Science, 2017) Juan Carlos Ramı́rez; Rudy Parrado; Elena Sulleiro; Anabelle de la Barra; Marcelo Rodríguez; Sandro Villarroel; Lucía Irazú; Cristina Alonso‐Vega; Fabiana Alves; María Á. Curto
    Real-Time PCR (qPCR) testing is recommended as both a diagnostic and outcome measurement of etiological treatment in clinical practice and clinical trials of Chagas disease (CD), but no external quality assurance (EQA) program provides performance assessment of the assays in use. We implemented an EQA system to evaluate the performance of molecular biology laboratories involved in qPCR based follow-up in clinical trials of CD. An EQA program was devised for three clinical trials of CD: the E1224 (NCT01489228), a pro-drug of ravuconazole; the Sampling Study (NCT01678599), that used benznidazole, both conducted in Bolivia; and the CHAGASAZOL (NCT01162967), that tested posaconazole, conducted in Spain. Four proficiency testing panels containing negative controls and seronegative blood samples spiked with 1, 10 and 100 parasite equivalents (par. eq.)/mL of four Trypanosoma cruzi stocks, were sent from the Core Lab in Argentina to the participating laboratories located in Bolivia and Spain. Panels were analyzed simultaneously, blinded to sample allocation, at 4-month intervals. In addition, 302 random blood samples from both trials carried out in Bolivia were sent to Core Lab for retesting analysis. The analysis of proficiency testing panels gave 100% of accordance (within laboratory agreement) and concordance (between laboratory agreement) for all T. cruzi stocks at 100 par. eq./mL; whereas their values ranged from 71 to 100% and from 62 to 100% at 1 and 10 par. eq./mL, respectively, depending on the T. cruzi stock. The results obtained after twelve months of preparation confirmed the stability of blood samples in guanidine-EDTA buffer. No significant differences were found between qPCR results from Bolivian laboratory and Core Lab for retested clinical samples. This EQA program for qPCR analysis of CD patient samples may significantly contribute to ensuring the quality of laboratory data generated in clinical trials and molecular diagnostics laboratories of CD.
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    Genetic polymorphism of <i>Trypanosoma cruzi</i> bloodstream populations in adult chronic indeterminate Chagas disease patients from the E1224 clinical trial
    (Oxford University Press, 2021) Juan Carlos Ramı́rez; Gonzalo R. Acevedo; Carolina Torres; Rudy Parrado; Anabelle de la Barra; Sandro Villarroel; Lineth García; Joaquím Gascón; Lourdes Ortiz; Faustino Torrico
    Genetic variability of T. cruzi bloodstream populations during post-treatment follow-up did not differ from that observed during chronic infection in the absence of treatment, suggesting that there were no selection events of E1224-resistant parasite populations. This is the first report documenting the genetic polymorphism of natural T. cruzi populations in chronic patients in the context of clinical trials with trypanocidal drugs.