ObjectiveTo evaluate the prevalence and possible factors associated with the development of burnout among medical students in the first years of undergraduate school.MethodA cross-sectional study was conducted at the Barretos School of Health Sciences, Dr. Paulo Prata. A total of 330 students in the first four years of medical undergraduate school were invited to participate in responding to the sociodemographic and Maslach Burnout Inventory-Student Survey (MBI-SS) questionnaires. The first-year group consisted of 150 students, followed by the second-, third-, and fourth-year groups, with 60 students each.ResultsData from 265 students who answered at least the sociodemographic questionnaire and the MBI-SS were analyzed (response rate = 80.3%). One (n = 1, 0.3%) potential participant viewed the Informed Consent Form but did not agree to participate in the study. A total of 187 students (187/265, 70.6%) presented high levels of emotional exhaustion, 140 (140/265, 52.8%) had high cynicism, and 129 (129/265, 48.7%) had low academic efficacy. The two-dimensional criterion indicated that 119 (44.9%) students experienced burnout. Based on the three-dimensional criterion, 70 students (26.4%) presented with burnout. The year with the highest frequency of affected students for both criteria was the first year (p = 0.001). Personal attributes were able to explain 11% (ΔR = 0.11) of the variability of burnout under the two-dimensional criterion and 14.4% (R2 = 0.144) under the three-dimensional criterion.ConclusionThis study showed a high prevalence of burnout among medical students in a private school using active teaching methodologies. In the first years of graduation, students’ personal attributes (optimism and self-perception of health) and school attributes (motivation and routine of the exhaustive study) were associated with higher levels of burnout. These findings reinforce the need to establish preventive measures focused on the personal attributes of first-year students, providing better performance, motivation, optimism, and empathy in the subsequent stages of the course.

Photodynamic antimicrobial chemotherapy (PACT) is a potential antimicrobial therapy that combines light and a photosensitizing drug, promoting a phototoxic effect on the treated cells, in general via oxidative damage. In this work we studied the effect of PACT, using methylene blue (MB), on the permeability of Candida albicans membrane. Our results demonstrated that the combination of MB and laser (684 nm) promoted a decrease in Candida growth. The inhibition was more pronounced in the presence of 0.05 mg/ml MB and with an energy density of 28 J/cm(2). The decrease in Candida growth was associated with an increase in membrane permeabilization. Thus, we suggest that a PACT mechanism using MB can be related to damage in the plasma membranes of the cells.

Mapping quantitative trait loci through the use of linkage disequilibrium (LD) in populations of unrelated individuals provides a valuable approach for dissecting the genetic basis of complex traits in soybean (Glycine max). The haplotype-based genome-wide association study (GWAS) has now been proposed as a complementary approach to intensify benefits from LD, which enable to assess the genetic determinants of agronomic traits. In this study a GWAS was undertaken to identify genomic regions that control 100-seed weight (SW), plant height (PH) and seed yield (SY) in a soybean association mapping panel using single nucleotide polymorphism (SNP) markers and haplotype information. The soybean cultivars (N = 169) were field-evaluated across four locations of southern Brazil. The genome-wide haplotype association analysis (941 haplotypes) identified eleven, seventeen and fifty-nine SNP-based haplotypes significantly associated with SY, SW and PH, respectively. Although most marker-trait associations were environment and trait specific, stable haplotype associations were identified for SY and SW across environments (i.e., haplotypes Gm12_Hap12). The haplotype block 42 on Chr19 (Gm19_Hap42) was confirmed to be associated with PH in two environments. These findings enable us to refine the breeding strategy for tropical soybean, which confirm that haplotype-based GWAS can provide new insights on the genetic determinants that are not captured by the single-marker approach.

Microbial diversity has been pointed out as a major factor in the development and progression of colorectal cancer (CRC). We sought to explore the richness and abundance of the microbial community of a series of colorectal tumor samples treated at Barretos Cancer Hospital, Brazil, through 16S rRNA sequencing. The presence and the impact of Fusobacterium nucleatum ( Fn ) DNA in CRC prognosis was further evaluated by qPCR in a series of 152 CRC cases. An enrichment for potentially oncogenic bacteria in CRC was observed, with Fusobacterium being the most abundant genus in the tumor tissue. In the validation dataset, Fn was detected in 35/152 (23.0%) of fresh-frozen tumor samples and in 6/57 (10.5%) of paired normal adjacent tissue, with higher levels in the tumor ( p = 0.0033). Fn DNA in the tumor tissue was significantly associated with proximal tumors ( p = 0.001), higher depth of invasion ( p = 0.014), higher clinical stages ( p = 0.033), poor differentiation ( p = 0.011), MSI-positive status ( p < 0.0001), BRAF mutated tumors ( p < 0.0001), and the loss of expression of mismatch-repair proteins MLH1 ( p < 0.0001), MSH2 ( p = 0.003), and PMS2 ( p < 0.0001). Moreover, the presence of Fn DNA in CRC tissue was also associated with a worse patient cancer-specific survival (69.9 vs. 82.2% in 5 years; p = 0.028) and overall survival (63.5 vs. 76.5%; p = 0.037). Here we report, for the first time, the association of F. nucleatum presence with important clinical and molecular features in a Brazilian cohort of CRC patients. Tumor detection and classification based on the gut microbiome might provide a promising approach to improve the prediction of patient outcome.

Resumo -A bioatividade de ácidos húmicos (AH) isolados de lodo da estação de tratamento de esgoto (AHL) e de vermicomposto (AHV) foi avaliada pela ação dessas substâncias sobre o transporte de prótons através da membrana plasmática de células de raízes de café e milho e sua relação com o desenvolvimento dessas espécies. Houve estímulo da área superficial radicular em ambas as espécies cultivadas com ambos AH, mostrando uma concentração ótima em torno de 40 mg L -1 . Nessa condição, os tratamentos com AHL e AHV estimularam a H + -ATPase de membrana plasmática em plântulas de café e milho. Os AHL foram mais efetivos na promoção desses efeitos do que os AHV. A modificação do perfil cromatográfico dos AH em solução antes e após o cultivo das plântulas revelou que a interação planta-AH promoveu uma redistribuição das massas moleculares dessas substâncias, sugerindo uma dinâmica de mobilização de subunidades funcionais dos AH por exsudatos das raízes. A análise estrutural dos AH detectou a presença de grupamentos de auxina. A análise comparativa da ação desses dois AH sobre as espécies representantes de plantas monocotiledôneas (milho) e dicotiledôneas (café) apontam para a ativação da H + -ATPase de plasmalema como possível marcador metabólico de bioatividade dos ácidos húmicos.Termos para indexação: Zea mays, Coffea arabica, lodo residual, ácidos orgânicos, vermicomposto. Humic acids bioactivity: effects on root development and on the plasma membrane proton pumpAbstract -The bioactivity of humic acids (HA) isolated from sludge of the station of sewer treatment (HAL) and from vermicompost (HAV) was evaluated through the action of those substances on primary transport of protons of the plasma membrane of coffee and corn root cells and its relationship with the development of those species. A stimulation in the superficial area of roots was observed for both species cultivated with both humic acids, exhibiting an optimum concentration, about 40 mg L -1 of HA. In this condition the treatment with HAL and HAV stimulated the plasma membrane H + -ATPase of corn and coffee roots. HAL were more effective to promote those effects than HAV. The modification of the chromatographic profile of the HA in solution before and after the cultivation of the seedlings revealed that the interaction plant-HA promoted a rearrangement of the average molecular weight of those substances suggesting a dynamic mobilization of bioactive subunits of the HA by plant exudates. The structural analysis of the HA has detected the presence of auxin groups. A comparative analysis of the action of those HA on the monocotyledonous (corn) and dicotyledonous (coffee) plants indicates to the activation of plasmallema H + -ATPase as a possible metabolic marker for bioactivity of humic acids.

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Lung cancer is the deadliest cancer worldwide. The mutational frequency of EGFR and KRAS genes in lung adenocarcinoma varies worldwide per ethnicity and smoking. The impact of EGFR and KRAS mutations in Brazilian lung cancer remains poorly explored. Thus, we investigated the frequency of EGFR and KRAS mutations in a large Brazilian series of lung adenocarcinoma together with patients’ genetic ancestry, clinicopathological and sociodemographic characteristics. The mutational frequency of EGFR was 22.7% and KRAS was 20.4%. The average ancestry proportions were 73.1% for EUR, 13.1% for AFR, 6.5% for AME and 7.3% for ASN. EGFR mutations were independently associated with never-smokers, high-Asian ancestry, and better performance status. KRAS mutations were independently associated with tobacco exposure and non-Asian ancestry. EGFR -exon 20 mutations were associated with worse outcome. The Cox regression model indicated a worse outcome for patients whose were older at diagnosis (>61 y), solid histological subtype, loss of weight (>10%), worse performance status (≥2), and presence of KRAS mutations and EGFR mutational status in TKi non-treated patients. In conclusion, we assessed the clinicopathological and ethnic impact of EGFR and KRAS mutations in the largest series reported of Brazilian lung adenocarcinomas. These findings can support future clinical strategies for Brazilian lung cancer patients.