Variability in baseline laboratory measurements of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Multi-center epidemiological studies must ascertain that their measurements are accurate and reliable. For laboratory measurements, reliability can be assessed through investigation of reproducibility of measurements in the same individual. In this paper, we present results from the quality control analysis of the baseline laboratory measurements from the ELSA-Brasil study. The study enrolled 15,105 civil servants at 6 research centers in 3 regions of Brazil between 2008–2010, with multiple biochemical analytes being measured at a central laboratory. Quality control was ascertained through standard laboratory evaluation of intra- and inter-assay variability and test-retest analysis in a subset of randomly chosen participants. An additional sample of urine or blood was collected from these participants, and these samples were handled in the same manner as the original ones, locally and at the central laboratory. Reliability was assessed with the intraclass correlation coefficient (ICC), estimated through a random effects model. Coefficients of variation (CV) and Bland-Altman plots were additionally used to assess measurement variability. Laboratory intra and inter-assay CVs varied from 0.86% to 7.77%. From test-retest analyses, the ICCs were high for the majority of the analytes. Notably lower ICCs were observed for serum sodium (ICC=0.50; 95%CI=0.31–0.65) and serum potassium (ICC=0.73; 95%CI=0.60–0.83), due to the small biological range of these analytes. The CVs ranged from 1 to 14%. The Bland-Altman plots confirmed these results. The quality control analyses showed that the collection, processing and measurement protocols utilized in the ELSA-Brasil produced reliable biochemical measurements.

Aumento da virulência de Candida albicans após tratamento de quimioterapia / Increased virulence of Candida albicans after antineoplastic chemotherapy

Although yeasts of the genus Candida are part of the normal human oral microbiota, in cancer patients they may be associated with invasive fungal infections. Antineoplastic therapy, with its adverse side effects, increases the likelihood of such infection. One of the important virulence factors is the capacity of yeast cells to adhere to the surface of medical devices inserted into patients. In this study, we tested the in vitro adhesive and film-growing capacity of four Candida albicans samples, isolated before and during chemotherapy from the oral cavity of a patient with adenocarcinoma. Adherence to the orotracheal tube (OTT) and biofilm production were assessed spectrophotometrically and the amount of film growth was estimated by measuring fungal metabolism. Also, the frequency and size of germ tubes were evaluated. The results showed a significant increase in the germ tube size of C. albicans and also an increase in yeast adherence to the OTT after the start of chemotherapy with mitoxantrone.

Embora as leveduras do gênero Candida pertençam a microbiota humana oral normal, em pacientes com câncer a sua presença pode estar associada a infecções fúngicas invasivas. O tratamento quimioterápico, com seus efeitos colaterais, aumenta as chances desta possibilidade. Um dos principais fatores de virulência consiste na capacidade das leveduras de se aderirem a superfície de instrumentos médicos inseridos nos pacientes. O presente estudo avaliou a capacidade in vitro de quatro isolados de Candida albicans, obtidos antes e após o início da quimioterapia de um paciente com adenocarcinoma. Estudos de adesão a tubo endotraqueal; produção de biofilme e quantificação por meio do metabolismo fúngico pelo XTT; frequência e tamanho de tubos germinativos foram realizados. Os resultados demonstraram aumento significante no tamanho do tubo germinativo, assim como o aumento da aderência dessas leveduras ao tubo endotraqueal após o início da quimioterapia com mitoxantrone.