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A class of constitutive relations for elastic bodies has been proposed recently, where the linearized strain tensor is expressed as a nonlinear function of the stress tensor. Considering this new type of constitutive equation, the initial boundary value problem for such elastic bodies has been expressed only in terms of the stress tensor. In this communication, this new type of nonlinear wave equation is studied for the case of a one-dimensional straight bar. Conditions for the existence of the travelling wave solutions are given and some self-similar solutions are obtained. [ABSTRACT FROM AUTHOR]

La evaluación de los aprendizajes constituye un proceso relevante de recogida de información para evidenciar avances y dificultades del proceso formativo de los estudiantes, y de las prácticas pedagógicas de los docentes, para tomar decisiones sustantivas y oportunas para mejorar la enseñanza y los aprendizajes. Para tal efecto, las evaluaciones de proceso cobran relevancia por su propósito formativo. Esta investigación tiene por objetivo comprender los significados y prácticas de evaluación formativa de docentes universitarios formadores de profesores, que imparten docencia en carreras de pedagogía en dos universidades chilenas. Para cumplir con dicho objetivo, se realizó un estudio cualitativo de tipo descriptivo – interpretativo, con un diseño fenomenológico que contempló la aplicación de una entrevista en profundidad y una observación no participante de clases a ocho docentes, cuatro de una universidad tradicional, y cuatro de una universidad privada. Los resultados evidencian que los docentes formadores de profesores comprenden la evaluación formativa como una herramienta que tiene como propósito la mejora del aprendizaje, pero sin planificación ni una definición de evaluación formativa, sino más bien son rasgos formativos que se entremezclan con un modelo tradicional de evaluación, donde el profesor tiene un rol poco preciso. En sus prácticas los docentes realizan acciones de evaluación formativa, pero las relacionan con actividades o productos concretos. Finalmente, se concluye que los docentes valoran la evaluación formativa como un proceso que les permite intervenir, corregir y modelar, pero sigue siendo pensada como un evento o instancia, más que un proceso reflexivo consustancial al proceso de aprendizaje.

Introduction: Breast cancer survivors often experience pre and post-treatment physical and psychological symptoms, negatively affecting their quality of life. Regular physical exercise is associated with better quality of life and lower recurrence of cancer, and therefore all oncological patients are recommended to practice it in a regular basis. Despite this, breast cancer survivors have low adherence to physical exercise. The purpose of this study is to identify barriers, facilitators and preferences of Chilean breast cancer survivors to practice physical exercise., Methods: Phenomenological qualitative study of 12 in-depth interviews with adjuvant radiation therapy concluded at least three months ago., Results: Breast cancer survivors ignored the benefits of physical exercise during and after treatment. The barriers were physical symptoms, psychological barriers, sociocultural barriers, health system barriers, disinformation and sedentary lifestyle. Facilitators were coping with physical symoptoms, psychological issues, having information and active lifestyle. The preferences were painless and familiar exercises. Preferred exercise was walking., Conclusions: Breast cancer survivors may adhere to physical exercise despite barriers when certain facilitators are present, which may be promoted by the health team when reporting the benefits of the physical exercise, prescribing personalized, safe and painless physical exercise and educating both patient and her family about the role of the physical exercise in cancer recovering process., Competing Interests: The authors declare that there are no potential conflicts of interest in relation to the research, authorship and/or publication of this study., (This work is licensed under a Creative Commons Attribution 4.0 International License.)

Despite the highly conserved nature of the genetic code, the frequency of usage of each codon can vary significantly. The evolution of codon usage is shaped by two main evolutionary forces: mutational bias and selection pressures. These pressures can be driven by environmental factors, but also by the need for efficient translation, which depends heavily on the concentration of transfer RNAs (tRNAs) within the cell. The data presented here supports the proposal that tRNA modifications play a key role in shaping the overall preference of codon usage in proteobacteria. Interestingly, some codons, such as CGA and AGG (encoding arginine), exhibit a surprisingly low level of variation in their frequency of usage, even across genomes with differing GC content. These findings suggest that the evolution of GC content in proteobacterial genomes might be primarily driven by changes in the usage of a specific subset of codons, whose usage is itself influenced by tRNA modifications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Delgado, Armijo, Bravo, Orellana, Salazar and Katz.)

Background and Aims: EUS-guided radiofrequency ablation (EUS-RFA) has emerged as an alternative for the local treatment of unresectable pancreatic ductal adenocarcinoma (PDAC). We assessed the feasibility and safety of EUS-RFA in patients with unresectable PDAC., Methods: This study followed an historic cohort compounded by locally advanced (LA-) and metastatic (m)PDAC-naïve patients who underwent EUS-RFA between October 2019 and March 2022. EUS-RFA was performed with a 19-gauge needle electrode with a 10-mm active tip for energy delivery. Study primary endpoints were feasibility, safety, and clinical follow-up, whereas secondary endpoints were performance status (PS), local control, and overall survival (OS)., Results: Twenty-six patients were selected: 15 with locally advanced pancreatic duct adenocarcinoma (LA-PDAC) and 11 with metastatic pancreatic duct adenocarcinoma (mPDAC). Technical success was achieved in all patients with no major adverse events. Six months after EUS-RFA, OS was seen in 11 of 26 patients (42.3%), with significant PS improvement (P = .03). Local control was achieved, with tumor reduction from 39.5 mm to 26 mm (P = .04). A post-treatment hypodense necrotic area was observed at the 6-month follow-up in 11 of 11 patients who were still alive. Metastatic disease was a significant factor for worsening OS (hazard ratio, 5.021; 95% confidence interval, 1.589-15.87; P = .004)., Conclusions: EUS-RFA for the treatment of pancreatic adenocarcinoma is a minimally invasive and safe technique that may have an important role as targeted therapy for local treatment of unresectable cases and as an alternative for poor surgical candidates. Also, RFA may play a role in downstaging cancer with a potential increase in OS in nonmetastatic cases. Large prospective cohorts are required to evaluate this technique in clinical practice., Competing Interests: Disclosure The following author disclosed financial relationships: C. Robles-Medranda: Key opinion leader and consultant for Pentax Medical, Steris, Micro-Tech, G-Tech Medical Supply, CREO Medical, EndoSound, and mdconsgroup. All other authors disclosed no financial relationships., (Copyright © 2024 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

Extreme acidophiles thrive in harsh environments characterized by acidic pH, high concentrations of dissolved metals and high osmolarity. Most of these microorganisms are chemolithoautotrophs that obtain energy from low redox potential sources, such as the oxidation of ferrous ions. Under these conditions, the mechanisms that maintain homeostasis of proteins (proteostasis), as the main organic components of the cells, are of utmost importance. Thus, the analysis of protein chaperones is critical for understanding how these organisms deal with proteostasis under such environmental conditions. In this work, using a bioinformatics approach, we performed a comparative genomic analysis of the genes encoding classical, periplasmic and stress chaperones, and the protease systems. The analysis included 35 genomes from iron- or sulfur-oxidizing autotrophic, heterotrophic, and mixotrophic acidophilic bacteria. The results showed that classical ATP-dependent chaperones, mostly folding chaperones, are widely distributed, although they are sub-represented in some groups. Acidophilic bacteria showed redundancy of genes coding for the ATP-independent holdase chaperones RidA and Hsp20. In addition, a systematically high redundancy of genes encoding periplasmic chaperones like HtrA and YidC was also detected. In the same way, the proteolytic ATPase complexes ClpPX and Lon presented redundancy and broad distribution. The presence of genes that encoded protein variants was noticeable. In addition, genes for chaperones and protease systems were clustered within the genomes, suggesting common regulation of these activities. Finally, some genes were differentially distributed between bacteria as a function of the autotrophic or heterotrophic character of their metabolism. These results suggest that acidophiles possess an abundant and flexible proteostasis network that protects proteins in organisms living in energy-limiting and extreme environmental conditions. Therefore, our results provide a means for understanding the diversity and significance of proteostasis mechanisms in extreme acidophilic bacteria., Competing Interests: The authors declare that there are no competing interests., (Copyright: © 2023 Izquierdo-Fiallo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: To determine late results of AS-DD procedure in long-segment (LSBE) and extralong-segment BE (ELSBE) using subjective and objective measurements to ascertain the histological impact over intestinal metaplasia (IM) and progression to EAC., Summary of Background Data: Barrett esophagus (BE) is a known precursor of esophageal adenocarcinoma (EAC), and Nissen fundoplication has proven to be unable to stop mixed reflux among them. Our group proposed a surgical procedure that handles pathophysiological changes responsible for BE., Methods: This prospective study included 127 LSBE and ELSBE subjects submitted to clinical and functional analyses. They were presented to selective vagotomy, fundoplication, partial gastrectomy with Roux-en-Y reconstruction. The changes in IM were determined in both groups., Results: Follow-up was completed at a mean of 18 years in 81% of the cases. Visick I-II scores were seen in 88% of LSBE and 65% in ELSBE ( P < 0.01). There was significant healing of erosive esophagitis and esophageal peptic ulcers, and strictures were resolved in 71%. There was 38% of IM regression in LSBE. Two cases in each group progressed to EAC at a mean of 15 years. Pathologic acid reflux was abolished in 91% and duodenal in 100%. There was a regression of low-grade dysplasia to IM in 80%., Conclusions: AS-DD permanently eliminates pathologic refluxate to the esophagus. The progression to HGD/EAC is lower compared to medical treatment, with an 8-fold reduction in LSBE and 2.2-fold in ELSBE. AS-DD seems to influence IM behaviors, and it is a tool that could reduce and delay progression to EAC., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Proteostasis refers to the processes that regulate the biogenesis, folding, trafficking, and degradation of proteins. Any alteration in these processes can lead to cell malfunction. Protein synthesis, a key proteostatic process, is highly-regulated at multiple levels to ensure adequate adaptation to environmental and physiological challenges such as different stressors, proteotoxic conditions and aging, among other factors. Because alterations in protein translation can lead to protein misfolding, examining how protein translation is regulated may also help to elucidate in part how proteostasis is controlled. Codon usage bias has been implicated in the fine-tuning of translation rate, as more-frequent codons might be read faster than their less-frequent counterparts. Thus, alterations in codon usage due to synonymous mutations may alter translation kinetics and thereby affect the folding of the nascent polypeptide, without altering its primary structure. To date, it has been difficult to predict the effect of synonymous mutations on protein folding and cellular fitness due to a scarcity of relevant data. Thus, the purpose of this work was to assess the effect of synonymous mutations in discrete regions of the gene that encodes the highly-expressed enzyme 3-phosphoglycerate kinase 1 ( pgk1 ) in the fission yeast Schizosaccharomyces pombe ., Results: By means of systematic replacement of synonymous codons along pgk1 , we found slightly-altered protein folding and activity in a region-specific manner. However, alterations in protein aggregation, heat stress as well as changes in proteasome activity occurred independently of the mutated region. Concomitantly, reduced mRNA levels of the chaperones Hsp9 and Hsp16 were observed., Conclusion: Taken together, these data suggest that codon usage bias of the gene encoding this highly-expressed protein is an important regulator of protein function and proteostasis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Moreira-Ramos, Arias, Flores, Katz, Levicán and Orellana.)

Introduction: The response of enterobacteria to oxidative stress is usually considered to be regulated by transcription factors such as OxyR and SoxR. Nevertheless, several reports have shown that under oxidative stress the levels, modification and aminoacylation of tRNAs may be altered suggesting a role of codon bias in regulation of gene expression under this condition., Methods: In order to characterize the effects of oxidative stress on translation elongation we constructed a library of 61 plasmids, each coding for the green fluorescent protein (GFP) translationally fused to a different set of four identical codons., Results: Using these reporters, we observed that GFP production levels vary widely (~15 fold) when Escherichia coli K-12 is cultured in minimal media as a consequence of codon choice variations. When bacteria are cultured under oxidative stress caused by paraquat the levels of GFP produced by most clones is reduced and, in contrast to control conditions, the range of GFP levels is restricted to a ~2 fold range. Restricting elongation of particular sequences does not increase the range of GFP production under oxidative stress, but altering translation initiation rates leads to an increase in this range., Discussion: Altogether, our results suggest that under normal conditions the speed of translation elongation is in the range of the speed of initiation and, consequently, codon choice impacts the speed of protein synthesis. In contrast, under oxidative stress translation initiation becomes much slower than elongation, limiting the speed of translation such that codon choice has at most only subtle effects on the overall output of translation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Leiva, Elgamal, Leidel, Orellana, Ibba and Katz.)

Fe-S clusters are versatile and essential cofactors that participate in multiple and fundamental biological processes. In Escherichia coli , the biogenesis of these cofactors requires either the housekeeping Isc pathway, or the stress-induced Suf pathway which plays a general role under conditions of oxidative stress or iron limitation. In the present work, the Fe-S cluster assembly Isc and Suf systems of acidophilic Bacteria and Archaea, which thrive in highly oxidative environments, were studied. This analysis revealed that acidophilic microorganisms have a complete set of genes encoding for a single system (either Suf or Isc). In acidophilic Proteobacteria and Nitrospirae, a complete set of isc genes ( iscRSUAX-hscBA-fdx ), but not genes coding for the Suf system, was detected. The activity of the Isc system was studied in Leptospirillum sp. CF-1 (Nitrospirae). RT-PCR experiments showed that eight candidate genes were co-transcribed and conform the isc operon in this strain. Additionally, RT-qPCR assays showed that the expression of the iscS gene was significantly up-regulated in cells exposed to oxidative stress imposed by 260 mM Fe 2 (SO 4 ) 3 for 1 h or iron starvation for 3 h. The activity of cysteine desulfurase (IscS) in CF-1 cell extracts was also up-regulated under such conditions. Thus, the Isc system from Leptospirillum sp. CF-1 seems to play an active role in stressful environments. These results contribute to a better understanding of the distribution and role of Fe-S cluster protein biogenesis systems in organisms that thrive in extreme environmental conditions.

Introduction: Laparoscopic Heller Myotomy (LHM) with partial anterior or posterior fundoplication is the standard surgical procedure for treating achalasia patients. The results reported are mainly based on symptomatic evaluations and have less than 5 years of follow-up and none more than ten., Objective: To determine the late results of LHM, performing endoscopic, histologic, manometric, and functional studies in addition to clinical evaluations., Materials and Methods: Eighty-nine consecutive patients were included in a prospective study from 1993 to 2008. Inclusion criteria corresponded to achalasia patients with Types I to III (radiological evaluation). Exclusion criteria included patients with grade IV, patients with previous procedures (surgical or endoscopic), or giant hiatal hernia. They were submitted to a radiological evaluation, over two endoscopic procedures with biopsy samples, manometric assessments, and 24-h pH monitoring late after surgery., Results: There was no operative mortality nor postoperative complications. The average hospital stay was two days. Nine patients (10.1%) were lost from follow-up. The mean late follow-up was 17 years (10-26). Visick I and II (success) corresponded to 78.7% of patients and grades III-IV (failure) to 21.3%, mainly due to gastroesophageal reflux disease (GERD). Manometric evaluations showed a significant and permanent decrease in lower esophageal sphincter pressure (LESP). 24-h pH monitoring was normal among Visick I patients and showed pathologic acid reflux in patients with GERD. Two patients (2.5%) developed Barrett's esophagus. Squamous-cell carcinoma (SCC) appeared in three patients (3.7%)., Conclusion: LHM controlled symptoms in 79% of achalasia patients very late (17 years) after surgery. This was corroborated by endoscopic, manometric, and functional studies. GERD symptoms developed in 18.7% and SCC in 3.7% in previously asymptomatic patients. Endoscopic surveillance at regular intervals is recommended for all patients who have had surgery. These very long-term results are a real challenge to POEM endoscopic treatment. Unique Identifying Registration Number 3743., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.)