Due to their importance in the regulation of metabolites, the kidneys need continuous monitoring to check for correct functioning, mainly by urea and creatinine urinalysis. This study aimed to develop a model to estimate the concentrations of urea and creatinine in urine by means of Raman spectroscopy (RS) that could be used to diagnose kidney disease. Midstream urine samples were obtained from 54 volunteers with no kidney complaints. Samples were subjected to a standard colorimetric assay of urea and creatinine and submitted to spectroscopic analysis by means of a dispersive Raman spectrometer (830 nm, 350 mW, 30 s). The Raman spectra of urine showed peaks related mainly to urea and creatinine. Partial least squares models were developed using selected Raman bands related to urea and creatinine and the biochemical concentrations in urine measured by the colorimetric method, resulting in r = 0.90 and 0.91 for urea and creatinine, respectively, with root mean square error of cross-validation (RMSEcv) of 312 and 25.2 mg/dL, respectively. RS may become a technique for rapid urinalysis, with concentration errors suitable for population screening aimed at the prevention of renal diseases.
SUMMARYThe natural co-infection with dengue virus can occur in highly endemic areas where different serotypes have been observed for many years. We report here four cases of DENV-3/DENV-4 co-infection detected by serological and molecular tests among 674 patients with acute undifferentiated fever from the tropical medicine reference center of Manaus City, Brazil, between 2005 and 2010. Analysis of the sequences obtained indicated the presence of genotype 3 and 1 for DENV-3 and DENV-4 respectively. KEYWORDS:Brazil; Dengue; Co-infection; Flavivirus.Dengue Fever is the most important arboviral disease worldwide. Dengue viruses (DENVs) belong to the genus Flavivirus, family Flaviviridae. These are single-stranded positive-sense RNA viruses grouped into four antigenically related, but distinct, serotypes named DENV-1, 2, 3 and 4 5 . Since the first laboratory-confirmed DENV cases at Roraima 1981-1982, more than four million cases of dengue have been reported in Brazil 11 . In Manaus, the capital of the Amazonas State in Brazil, all four dengue serotypes have already been reported 3,4 . Dengue virus co-infection cases are poorly documented in literature, although our results demonstrate that such cases might be more common than expected, mostly in hyperendemic areas.From January 2005 to December 2010, 674 patients with acute undifferentiated fever were treated at a reference center of Tropical Medicine (Fundação de Medicina Tropical Doutor Heitor Vieira Dourado -FMT-HVD, Manaus, Brazil). These patients were tested for malaria by thick blood analyses, and all patients with negative results were asked to participate in this study. The participants signed an informed consent form that was approved by the FMTAM Ethical Committee Board (272/2005). Two blood samples were collected from each patient, one in the acute phase of the disease and the other in the convalescent form. Sera from the convalescent phase were used for detection of antidengue immunoglobulin M (IgM) specific antibodies by MAC-ELISA, as previously described 9 .Acute-phase samples were used in two tests: one for viral isolation in C6/36 Aedes albopictus cell line, followed by viral identification using an indirect immunofluorescent test with dengue type-specific monoclonal antibodies 7 , kindly provided by Centers for Disease Control and Prevention (CDC), Atlanta, Georgia USA; and the other for specific DENV nucleic acid amplification. RNA was extracted directly from serum samples with the QIAamp Viral RNA Mini-Kit (Qiagen, USA), following manufacturer´s instructions and submitted to RT-PCR to be followed by semi-nested multiplex PCR as previously described for DENV detection and typing 10 . When samples were positive for any serotype of DENV, a second semi-nested PCR, this time in a singleplex format, with a type-specific primer (DENV-1 to DENV-4) was performed for confirmation. Amplicons from the C/PrM region were purified and sequenced in both directions by using the BigDye Terminator Cycle Sequence Kit (Applied Biosystems, USA). The genotypes were detec...
Urea and creatinine are commonly used as biomarkers of renal function. Abnormal concentrations of these biomarkers are indicative of pathological processes such as renal failure. This study aimed to develop a model based on Raman spectroscopy to estimate the concentration values of urea and creatinine in human serum. Blood sera from 55 clinically normal subjects and 47 patients with chronic kidney disease undergoing dialysis were collected, and concentrations of urea and creatinine were determined by spectrophotometric methods. A Raman spectrum was obtained with a high-resolution dispersive Raman spectrometer (830 nm). A spectral model was developed based on partial least squares (PLS), where the concentrations of urea and creatinine were correlated with the Raman features. Principal components analysis (PCA) was used to discriminate dialysis patients from normal subjects. The PLS model showed r = 0.97 and r = 0.93 for urea and creatinine, respectively. The root mean square errors of cross-validation (RMSECV) for the model were 17.6 and 1.94 mg/dL, respectively. PCA showed high discrimination between dialysis and normality (95 % accuracy). The Raman technique was able to determine the concentrations with low error and to discriminate dialysis from normal subjects, consistent with a rapid and low-cost test.
INTRODUCTION Mayaro virus (MAYV) was found in Pará state, Brazil, in 1955. Since then, sporadic outbreaks have occurred in different regions of the country. METHODS: Serum sample were collected from 49 individuals in 2016 and were initially tested for dengue virus (DENV) by real-time (RT) polymerase chain reaction (PCR). DENV-negative samples were tested for MAYV and Oropouche virus (OROV) by multiplexed RT quantitative PCR. RESULTS: All samples were negative for DENV and OROV, but MAYV was detected in four samples. CONCLUSIONS: Differential diagnoses of acute febrile syndrome are required, especially in regions where several arboviruses with similar clinical manifestations are endemic.
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