Search

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi (T. cruzi), affects millions of people worldwide. Polymerase Chain Reaction (PCR) and real-time quantitative PCR (qPCR) have been used as tools to monitor parasitic levels in the bloodstream of individuals exposed to infection, thus enabling the monitoring of relapses and the effectiveness of therapy, for example. The aim of this study was to evaluate the TcSAT-IAM system, developed by our research group, on samples from patients with suspected Chagas disease infection. Initially, primer systems were developed for the detection of the nuclear DNA (SAT-DNA) from T. cruzi (TcSAT-IAM). The Cruzi system, predicted in the literature, and TcSAT-IAM were then evaluated in relation to their analytical sensitivity, specificity and efficiency. Afterwards, the applicability of the qPCR technique using both systems (separately) for the diagnosis of acute CD was evaluated in samples from 77 individuals exposed to the outbreak that occurred in Pernambuco-Brazil, relating the results obtained to those of the classical diagnostic methods recommended for this stage of the infection. TcSAT-IAM and Cruzi had a detection limit of 1 fg of target DNA (0,003 parasites). Thirty-eight cases were recorded, 28 by laboratory criteria and 10 by clinical and epidemiological criteria. Blood samples from 77 subjects were submitted to qPCR by both systems, reaching an agreement of 89.61% between them. After analyzes between systems and diagnostic criteria, the TcSAT-IAM showed sensitivity and specificity of 52.36% (CI 37.26-67.52) and 92.31% (CI 79.68-97.35), respectively, accuracy of 72.73% and moderate agreement. The TcSAT-IAM showed an accuracy of 72.58% and 75% in relation to parasitological and serological tests (IgM anti-T. cruzi), respectively. Therefore, quantitative PCR should be incorporated into the diagnosis of suspected acute cases of Chagas disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Sugarcane bagasse was used as an inexpensive alternative carbon source for production of β-xylanases from Aspergillus terreus. The induction profile showed that the xylanase activity was detected from the 6th day of cultivation period. Two low molecular weight enzymes, named Xyl T1 and Xyl T2 were purified to apparent homogeneity by ultrafiltration, gel filtration and ion exchange chromatographies and presented molecular masses of 24.3and 23.60 kDa, as determined by SDS-PAGE, respectively. Xyl T1 showed highest activity at 50 °C and pH 6.0, while Xyl T2 was most active at 45 °C and pH 5.0. Mass spectrometry analysis of trypsin digested Xyl T1 and Xyl T2 showed two different fingerprinting spectra, indicating that they are distinct enzymes. Both enzymes were specific for xylan as substrate. Xyl T1 was inhibited in greater or lesser degree by phenolic compounds, while Xyl T2 was very resistant to the inhibitory effect of all phenolic compounds tested. The apparent km values of Xyl T2, using birchwood xylan as substrate, decreased in the presence of six phenolic compounds. Both enzymes were inhibited by N-bromosuccinimide and Hg(2+) and activated by Mn(2+). Incubation of Xyl T1 and Xyl T2 with L-cysteine increased their half-lives up to 14 and 24 h at 50 °C, respectively. Atomic force microscopy showed a bimodal size distribution of globular particles for both enzymes, indicating that Xyl T1 is larger than Xyl T2., (Copyright © 2013 Elsevier Inc. All rights reserved.)