Clinical decision limits as criteria for setting analytical performance specifications for laboratory tests

Peer reviewe

Differentiating Plasmodium falciparum alleles by transforming Cartesian X,Y data to polar coordinates

<p>Abstract</p> <p>Background</p> <p>Diagnosis of infectious diseases now benefits from advancing technology to perform multiplex analysis of a growing number of variables. These advances enable simultaneous surveillance of markers characterizing species and strain complexity, mutations associated with drug susceptibility, and antigen-based polymorphisms in relation to evaluation of vaccine effectiveness. We have recently developed assays detecting single nucleotide polymorphisms (SNPs) in the <it>P. falciparum </it>genome that take advantage of post-PCR ligation detection reaction and fluorescent microsphere labeling strategies. Data from these assays produce a spectrum of outcomes showing that infections result from single to multiple strains. Traditional methods for distinguishing true positive signal from background can cause false positive diagnoses leading to incorrect interpretation of outcomes associated with disease treatment.</p> <p>Results</p> <p>Following analysis of <it>Plasmodium falciparum </it>dihydrofolate reductase SNPs associated with resistance to a commonly used antimalarial drug, Fansidar (Sulfadoxine/pyrimethamine), and presumably neutral SNPs for parasite strain differentiation, we first evaluated our data after setting a background signal based on the mean plus three standard deviations for known negative control samples. Our analysis of single allelic controls suggested that background for the absent allele increased as the concentration of the target allele increased. To address this problem, we introduced a simple change of variables from customary (<it>X,Y</it>) (Cartesian) coordinates to planar polar coordinates (<it>X </it>= <it>r</it>cos(<it>θ</it>), <it>Y </it>= <it>r</it>sin(<it>θ</it>)). Classification of multidimensional fluorescence signals based on histograms of angular and radial data distributions proved more effective than classification based on Cartesian thresholds. Comparison with known diallelic dilution controls suggests that histogram-based classification is effective for major:minor allele concentration ratios as high as 10:1.</p> <p>Conclusion</p> <p>We have observed that the diallelic SNP data resulting from analysis of <it>P. falciparum </it>mutations is more accurately diagnosed when a simple polar transform of the (<it>X,Y</it>) data into (<it>r,θ</it>) is used. The development of high through-put methods for genotyping <it>P. falciparum </it>SNPs and the refinement of analytical approaches for evaluating these molecular diagnostic results significantly advance the evaluation of parasite population diversity and antimalarial drug resistance.</p

Geração de tecnologias para a produção sustentável e processamento de frutos de açaí no estuário amazônico.

Publicado também: FRAZÃO, D. A. C.; HOMMA, A. K. O; VIÉGAS, I. de J. M. (Ed.). Contribuição ao desenvolvimento da fruticultura na Amazônia. Belém, PA: Embrapa Amazônia Oriental, 2006. p. 113-117

Differentially Expressed in Chondrocytes 2 (DEC2) Increases the Expression of IL-1 beta and Is Abundantly Present in Synovial Membrane in Rheumatoid Arthritis

Objective Patients with rheumatoid arthritis (RA) have altered circadian rhythm of circulating serum cortisol, melatonin and IL-6, as well as disturbance in the expression of clock genes ARNTL2 and NPAS2. In humans, TNF alpha increases the expression ARNTL2 and NPAS2 but paradoxically suppresses clock output genes DPB and PER3. Our objective was to investigate the expression of direct clock suppressors DEC1 and DEC2 (BHLHE 40 and 41 proteins) in response to TNF alpha and investigate their role during inflammation. Methods Cultured primary fibroblasts were stimulated with TNF alpha. Effects on DEC2 were studied using RT-qPCR and immunofluorescence staining. The role of NF-kappa B in DEC2 increase was analyzed using IKK-2 specific inhibitor IMD-0354. Cloned DEC2 was transfected into HEK293 cells to study its effects on gene expression. Transfections into primary human fibroblasts were used to confirm the results. The presence of DEC2 was analyzed in (RA) and osteoarthritis (OA) synovial membranes by immunohistochemistry. Results TNF alpha increased DEC2 mRNA and DEC2 was mainly detected at nuclei after the stimulus. The effects of TNF alpha on DEC2 expression were mediated via NF-kappa B. Overexpression, siRNA and promoter activity studies disclosed that DEC2 directly regulates IL-1 beta, in both HEK293 cells and primary human fibroblasts. DEC2 was increased in synovial membrane in RA compared to OA. Conclusion Not only ARNTL2 and NPAS2 but also DEC2 is regulated by TNF alpha in human fibroblasts. NF-kappa B mediates the effect on DEC2, which upregulates IL-1 beta. Circadian clock has a direct effect on inflammation in human fibroblasts.Peer reviewe

Manejo e cultivo de açaizais para produção de frutos.

Os açaizais, áreas de florestas de varzea dominadas pela palmeira Euterpe oleracea, são um recurso florestal não-madeireiro da região do Estuario Amazônico