Gene expression study using real-time PCR identifies an NTR gene as a major marker of resistance to benznidazole in Trypanosoma cruzi

<p>Abstract</p> <p>Background</p> <p>Chagas disease is a neglected illness, with limited treatments, caused by the parasite <it>Trypanosoma cruzi</it>. Two drugs are prescribed to treat the disease, nifurtimox and benznidazole, which have been previously reported to have limited efficacy and the appearance of resistance by <it>T. cruzi</it>. Acquisition of drug-resistant phenotypes is a complex physiological process based on single or multiple changes of the genes involved, probably in its mechanisms of action.</p> <p>Results</p> <p>The differential genes expression of a sensitive <it>Trypanosoma cruzi </it>strain and its induced <it>in vitro </it>benznidazole-resistant phenotypes was studied. The stepwise increasing concentration of BZ in the parental strain generated five different resistant populations assessed by the IC₅₀ranging from 10.49 to 93.7 μM. The resistant populations maintained their phenotype when the BZ was depleted from the culture for many passages. Additionally, the benznidazole-resistant phenotypes presented a cross-resistance to nifurtimox but not to G418 sulfate. On the other hand, four of the five phenotypes resistant to different concentrations of drugs had different expression levels for the 12 genes evaluated by real-time PCR. However, in the most resistant phenotype (TcR5x), the levels of mRNA from these 12 genes and seven more were similar to the parental strain but not for NTR and OYE genes, which were down-regulated and over-expressed, respectively. The number of copies for these two genes was evaluated for the parental strain and the TcR5x phenotype, revealing that the NTR gene had lost a copy in this last phenotype. No changes were found in the enzyme activity of CPR and SOD in the most resistant population. Finally, there was no variability of genetic profiles among all the parasite populations evaluated by performing low-stringency single-specific primer PCR (LSSP-PCR) and random amplified polymorphic DNA RAPD techniques, indicating that no clonal selection or drastic genetic changes had occurred for the exposure to BZ.</p> <p>Conclusion</p> <p>Here, we propose NTR as the major marker of the appearance of resistance to BZ.</p

High-Resolution Melting (HRM) of the Cytochrome B Gene: A Powerful Approach to Identify Blood-Meal Sources in Chagas Disease Vectors

Methods to determine blood-meal sources of hematophagous Triatominae bugs (Chagas disease vectors) are serological or based on PCR employing species-specific primers or heteroduplex analysis, but these are expensive, inaccurate, or problematic when the insect has fed on more than one species. To solve those problems, we developed a technique based on HRM analysis of the mitochondrial gene cytochrome B (Cyt b). This technique recognized 14 species involved in several ecoepidemiological cycles of the transmission of Trypanosoma cruzi and it was suitable with DNA extracted from intestinal content and feces 30 days after feeding, revealing a resolution power that can display mixed feedings. Field samples were analyzed showing blood meal sources corresponding to domestic, peridomiciliary and sylvatic cycles. The technique only requires a single pair of primers that amplify the Cyt b gene in vertebrates and no other standardization, making it quick, easy, relatively inexpensive, and highly accurate

Iterative Flattening Search for the Flexible Job Shop Scheduling Problem

This paper presents a meta-heuristic algorithm for solving the Flexible Job Shop Scheduling Problem (FJSSP). This strategy, known as Iterative Flattening Search (IFS), iteratively applies a relaxation-step, in which a subset of scheduling decisions are randomly retracted from the current solution; and a solving-step, in which a new solution is incrementally recomputed from this partial schedule. This work contributes two separate results: (1) it proposes a constraint-based procedure extending an existing approach previously used for classical Job Shop Scheduling Problem; (2) it proposes an original relaxation strategy on feasible FJSSP solutions based on the idea of randomly breaking the execution orders of the activities on the machines and opening the resource options for some activities selected at random. The efficacy of the overall heuristic optimization algorithm is demonstrated on a set of well-known benchmarks

Evaluación del impacto social de la Licenciatura en Educación Especial en dos subregiones de Antioquia, Colombia

This research paper presents the results of the evaluation of the social impact of the Special Education undergraduate program, of the University of Antioquia’s Education Faculty, in the East and Southwest subregions of the Antioquia department (Colombia). The main objective was to evaluate the impact of the Program among the graduates and other audiences. The methodology was carried out under a qualitative design, in the evaluative research modality, Social Programs impact type of evaluation. The results of the research were structured under the following categories: Assessment of the quality of the Program, the role of the Special Educator, significant experiences and their impact, and location and working conditions of the graduates. Finally, it poses recommendations to various academic units of the University.Keywords: special education, evaluation, social impact, graduates, occupational performance, assessment.En el presente artículo se dan a conocer los resultados de la evaluación del impacto social del programa de Licenciatura en Educación Especial, Facultad de Educación de la Universidad de Antioquia, en las subregiones de Oriente y Suroeste del departamento de Antioquia (Colombia), cuyo objetivo principal fue evaluar el impacto del Programa desde los egresados y otras audiencias. La metodología se llevó a cabo bajo un diseño cualitativo, modalidad de investigación evaluativa, tipo de evaluación de impacto de programas sociales. Los resultados se estructuraron bajo las categorías: valoración de la calidad del Programa, rol del educador especial, experiencias significativas y su impacto, y ubicación y condiciones laborales de los egresados y egresadas. Finalmente, se plantean recomendaciones a diferentes unidades académicas de la Universidad

A nationwide pilot study on breast cancer screening in Peru

"Introduction: A high prevalence of advanced breast cancer (BC) is a common scenario in Latin America. In Peru, the frequency of BC at Stages III/IV is ≈50% despite implementation of a programme for breast cancer screening (BCS) along the country. We carried out a study to assess the feasibility and develop an instrument to evaluate the knowledge, barriers and perception about BCS in a nationwide pilot study in Peru among candidates for BCS. Methods: We conducted a systematic review of 2,558 reports indexed in PubMed, Scopus, Web of Science, Medline-Ovid and EMBASE, regarding to our study theme. In total, 111 were selected and a 51-items survey was developed (eight items about sociodemographic characteristics). Patients were recruited in public hospitals or private clinics, in rural and urban areas of nine departments of Peru. Results: We surveyed 488 women from: Lima (150), Cajamarca (93), Ica (59), Arequipa (56), Loreto (48), Ancash (38), Junín (15), Puerto Maldonado (15) and Huancavelica (14); 27.9% of them were from rural areas. The mean of age was 53.3 years (standard deviation ± 9.1). Regarding education level, 29.8% had primary, 33.2% secondary and 37.0% higher education. In total, 28.7% of women did not know the term ‘mammogram’ and 47.1% reported never receiving a BCS (36.9% from urban and 73.5% from rural population). In women that underwent BCS, only 67% knew it is for healthy women. In total, 54.1% of patients had low levels of knowledge about risk factors for BC (i.e. 87.5% of women respond that injuries in the breast produce cancer). Cultural, economic and geographic barriers were significantly associated with having a mammogram where 56.9% of participants considered a cost ≤ 7 USD as appropriate. Mammogram was perceived as too painful for 54.9% of women. In addition, women with a self-perception of low-risk for BC and a fatalistic perception of cancer were less likely to have a BCS. Conclusion: We found that it is feasible to conduct a large-scale study in Peru. The results of this pilot study highlight an urgent need of extensive education and awareness about BCS in Peru.

The genomic landscape of molecular responses to natural drought stress in Panicum hallii

© 2018, The Author(s). Environmental stress is a major driver of ecological community dynamics and agricultural productivity. This is especially true for soil water availability, because drought is the greatest abiotic inhibitor of worldwide crop yields. Here, we test the genetic basis of drought responses in the genetic model for C4 perennial grasses, Panicum hallii, through population genomics, field-scale gene-expression (eQTL) analysis, and comparison of two complete genomes. While gene expression networks are dominated by local cis-regulatory elements, we observe three genomic hotspots of unlinked trans-regulatory loci. These regulatory hubs are four times more drought responsive than the genome-wide average. Additionally, cis- and trans-regulatory networks are more likely to have opposing effects than expected under neutral evolution, supporting a strong influence of compensatory evolution and stabilizing selection. These results implicate trans-regulatory evolution as a driver of drought responses and demonstrate the potential for crop improvement in drought-prone regions through modification of gene regulatory networks

Canto de cigarras

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