There is no consensus on the myocardial ischemia/reperfusion injury induction methods in animal studies

Dear Editor: Ischemic heart diseases (IHDs) are among the most important causes of death and disability worldwide. Every year, 10.6 million people are diagnosed with IHDs; in 2017, 8.9 million died due to this disease (1). The treatment of myocardial infarction is principally based on prompt blood supply restoration to salvage the ischemic tissue utilizing timely thrombolytic medications and coronary revascularization (2). However, the subsequent reperfusion provokes secondary cellular damage, broadly referred to as reperfusion injury (3). Although a compendium of therapeutic agents has been proposed to allay the detrimental consequences of reperfusion, they do not yet have desirable efficacies, and the research for discovering novel promising treatments is still ongoing. Preclinical studies are integral to the translation of preliminary research into clinical practice. Conventionally, plausible treatments and innovative drugs are tested in animal experiments to ascertain their effectiveness and safety. Experimentations on cardiac Ischemia/reperfusion injuries comprise a significant body of literature among the preclinical studies, and one can find a myriad of evidence in online databases. Through our systematic reviews, we have encountered various myocardial ischemia/reperfusion (I/R) models, including large vessel ligation, global ischemia by administrating Isoproterenol, and interrupted perfusion of isolated hearts mounted on the Langendorff apparatus. Moreover, the studies were inconsistent regarding the duration of ischemia and, the subsequent reperfusion phase(4, 5). The secondary damages in the course of I/R injury are proportionate to the extent and duration of the ischemia (6). Moreover, Pathways leading to myocardial damage during I/R injury are considered a dynamic and evolving process (7). Therefore, the efficacy of interventions in mitigating I/R injury may be misestimated depending on the duration of the ischemic and reperfusion phases. To surmount these concerns, we suggest an expert panel develop standardized guidelines for myocardial I/R injury induction in experimental studies to consolidate further the reliability and validity of the results obtained from preclinical studies, ultimately contributing to the better appraisal of the studies. In the meantime, tissue markers representative of the degree of infarction or tissue fibrosis can be used to compare the induced ischemia/reperfusion injuries in studies

Detection of Efflux MexAB-associated Multidrug Resistant (MDR) Pseudomonas aeruginosa Isolated from Patients in Torbat Heydarie, Northeast Iran

Background: Pseudomonas aeruginosa (P. aeruginosa) is one of the leading causes of hospital acquired infections. Infections with P. aeruginosa are often hard to treat because of existence of different mechanisms of antibiotic resistance changes in permeability of drugs and activity multidrug efflux pumps. The aim of current study was to determine the antibiotic resistance pattern of P. aeruginosa and existence of efflux pump MexAB genes using PCR technique.Materials and Methods: 506 isolates cultured from different clinical specimens of patients hospitalized at Nohom Dey and Razi hospitals of Torbat Heydarie (northeast Iran) were collected and used in this study. Isolates were identified using conventional bacteriology and their susceptibility to different antibiotics were assessed using agar disk diffusion method. The PCR assay was used to detect efflux pump MexAB genes.Results: From 506 isolates, 50 were identified as P. aeruginosa and these were isolated from isolated from blood, tracheal, burn, and wound. Incidence of P. aeruginosa was greater in males than females, wound infections had the highest number of occurrence and patients between 30-50 years were the most infected age group. In total, 60.86% of strains were multidrug resistant (MDR). The PCR technique revealed that most of the P. aeruginosa isolates and all the MDR strains contained MexA and MexB genes.Conclusions: The emergence of MDR microorganisms poses serious therapeutic problems for patients. Determining bacterial resistance mechanisms is complex. In this way, efflux systems were responsible for antibiotic resistance and played an important role in the MDR phenotype among P. aeruginosa isolates

An Efficient Entropy-Based Method for Reliability Assessment by Combining Kriging Meta-Models

Meta-models or surrogate models are convenient tools for reliability assessment of problems with time-consuming numerical models. Recently, an adaptive method called AK-MCS has been widely used for reliability analysis by combining Mont-Carlo simulation method and Kriging surrogate model. The AK-MCS method usually uses constant regression as a Kriging trend. However, other regression trends may have better performance for some problems. So, a method is proposed by combining multiple Kriging meta-models with various trends. The proposed method is based on the maximum entropy of predictions to select training samples. Using multiple Kriging models can reduce the sensitivity to the regression trend. So, the propped method can have better performance for different problems. The proposed method is applied to some examples to show its efficiency

Effect of Manganese (Mn) Content and Homogenization Treatment on Hot Deformation of AA3xxx Aluminum Alloys

In the current study the effect of Mn content and homogenization heat treatment on the hot deformation behavior of AA3XXX aluminum alloy was investigated. Three Mn contents of 0.05, 0.29 and 1.04 wt.% were considered. These alloys were subjected to a single-step heat treatment (H1), two two-steps heat treatments (H2 and H3) cycles. Electrical conductivity measurements were applied on as-cast alloys and after three homogenization treatments in order to evaluate the Mn content in the solid solution on the AA3XXX aluminum alloys. Hot deformation of the alloys was conducted using Gleeble 3500 machine, under plane strain conditions up to a final strain of 0.5. The deformation strain rate was selected as 0.1, 1.0 and 10 s-1, and deformation temperature was ranged between 300-500°C with 100°C temperature steps. Using the flow curves obtained from the Gleeble tests, the constitutive behavior of the materials was developed. Moreover, dislocation density and stored energy after hot deformation of AA3XXX aluminum alloys were calculated. The deformed materials were characterized using optical microscopy and image analyzing software to measure as-cast area fraction of the constituent particles and the size and aspect ratio of the constituent particles before and after hot deformation. Recovery model is able to capture the softening behavior of the Al-1%Mn alloy that has a close chemical composition to an alloy with 0.05 wt% Mn

Familiarity of Physicians and Nurses with Different Aspects of Oxygen Therapy; a Brief Report

Introduction: Oxygen is a drug and physician and nurses should be familiar with the effects and potential risks of oxygen therapy. The current study aimed to assess familiarity of physicians and nurses with various aspects of oxygen therapy.Method: In this cross sectional study, the familiarity of physicians and nurses with various aspects of oxygen therapy in a teaching hospital was evaluated using a validated questionnaire. The collected data were analyzed using SPSS 21 software.Results: 57 physicians and 79 nurses returned the completed questionnaire (response rate 97.1%). Mean clinical work experience of participants was 6.9±5.7 (1–15) years.98.2% of physicians believed that oxygen therapy can be associated with risk and should be recorded in the patient's medical file. These measures were 92.4% and 98.2% for nurses. 38 (27.9%) participants correctly pointed out the reasons for oxygen therapy. Regarding necessary measurements and monitoring for oxygen therapy, 49 (86%) physicians and 65 (82.3%) nurses chose the correct answer. In addition, regarding necessity of blood gas analysis during oxygen therapy, 44 (77.2%) physicians and 55 (69.6%) nurses chose the correct answer.Conclusion: The findings showed that the familiarity level of participants with some aspects of O2 therapy such as its indications, necessary measurements and monitoring during therapy, and identifying delivery devices was fair to weak (<80%)

The Impact of Gender, Nativeness, and Subject Matter on the English as a Second Language University Students’ Perception of Instructor Credibility and Engagement: A Qualitative Study

In instructional contexts, instructor credibility or ethos is deemed to play a paramount role in teacher–student interaction and relationships. Much effort has been devoted to instructor credibility conceptualization, measurement, and its association with other instructional variables of interest in dominantly quantitative inquiries. However, little research has been undertaken in second-language education in which communication is both a means and an end. This qualitative research set out to explore the perception of the students of instructor credibility in the context of higher English education and how gender, nativeness, and subject matter might impact their perceptions. It also aimed to study how instructor credibility could, in turn, influence the engagement and success of the students. Thirteen senior students of English as a foreign language from a university in Iran participated in this study. They were given a scenario about their prospective professors for two courses of “Research Methodology” and “Essay Writing.” The professors included four native English- and Persian-speaking male and female PhD holders. The participants were, then, interviewed about their perceptions of instructor credibility, their choices of instructors, and how they would affect their engagement. The data were recorded, transcribed, and recursively analyzed using an inductive thematic analysis. While instructor credibility is commonly characterized as a three-dimensional construct, involving competence, character, and caring, the data analysis generated a new component of performance concerned with the effectiveness of classroom knowledge presentation and activity organization. Caring also emerged as a constituent of a more inclusive component of rapport. Interestingly, albeit they viewed native English professors as generally more competent due to their nativeness, they perceived non-native professors as more credible for both courses, mainly because of their rapport building and familiarity with the needs and challenges of the students. Most of the participants also viewed male professors as more competent and communicative for both courses. The participants also tended to argue that perceived instructor credibility would encourage them to put in more effort in their academic undertakings and to engage in class activities. This would ultimately enhance their academic achievements and success. The paper discusses the findings and implications for second-language instructor credibility conceptualization and practice

Intravenous Amiodarone versus Digoxin in Atrial Fibrillation Rate Control; a Clinical Trial

Introduction: Treatment of rapid ventricular response arterial fibrillation (rapid AF) varies depending on the decision of the in-charge physician, condition of the patient, availability of the drug, and the treatment protocol of the hospital. The present study was designed aiming to compare IV digoxin and amiodarone in controlling the heart rate of patients presenting to emergency department with rapid AF and relative contraindication for first line drug in this regard.Method: In the present clinical trial, patients presented to the ED with rapid AF and relative contraindication for calcium channel blockers and beta-blockers were treated with either IV amiodarone or IV digoxin and compared regarding success rate and complication using SPSS version 22. P < 0.05 was considered as statistically significant.Results: 84 patients were randomly allocated to either amiodarone or digoxin treatment groups of 42 (53.6% male). The mean age of the studied patients was 61.8 ± 11.14 years (38 - 79). No significant difference was present regarding baseline characteristics. The rate of treatment failure was 21.4% (9 cases) in amiodarone and 59.5% (25 cases) in digoxin groups (p < 0.001). The mean onset of action was 56.66 ± 39.52 minutes (10 - 180) in amiodarone receivers and 135.38 ± 110.41 minutes (25 - 540) in digoxin group (p < 0.001). None of the patients showed any adverse outcomes of hypotension, bradycardia, and rhythm control.Conclusion: Based on the findings of the present study, rapid AF patients with relative contraindication for calcium channel blockers or beta-blockers who had received amiodarone experienced both higher (about 2 times) treatment success and a more rapid (about 2.5 times) response compared to those who received IV digoxin