Distinct load dependence of relaxation rate and diastolic function in Oryctolagus cuniculus and Ratus norvegicus

This study investigated potential differences on load dependence of relaxation rate and diastolic function between Oryctolagus cuniculus and Ratus norvegicus, which have constitutive differences in the mechanisms involved in myocardial inactivation. Load dependence of relaxation rate and diastolic function were evaluated with the response of left ventricular time constant tau and diastolic pressure-dimension relation to beat-to-beat aortic constrictions in open-chest rabbits and rats. Afterload levels were normalized, being expressed as a percentage of peak isovolumetric pressure (relative load). In control heartbeats, relaxation rate and diastolic function were similar in the two animal species. They presented, however, distinct responses to afterload elevations. In rabbits, time constant decreased similar to7% and diastolic pressure-dimension relation remained unchanged when afterload was elevated to a relative load of 73-76%. Above this afterload level, a significant deceleration of relaxation rate (increase of time constant) and an upward shift of diastolic pressure-dimension relation were observed. In rats, afterload elevations accelerated pressure fall up to a relative load of 97-100% and no afterload-induced shift of the diastolic pressure-dimension relation was observed. This study provides, therefore, evidence that Oryctolagus cuniculus has lower afterload reserve of myocardial relaxation and diastolic function than Ratus norvegicus

Oxidative stress in asthmatic and non-asthmatic adolescent swimmers - a breathomics approach

We hypothesize that oxidative stress induced by trichloramine exposure during swimming could be related to etiopathogenesis of asthma among elite swimmers. Aim: To investigate the effect of a swimming training session on oxidative stress markers of asthmatic compared to non‐asthmatic elite swimmers using exhaled breath (EB) metabolomics. Methods: Elite swimmers annually screened in our department (n=27) were invited and those who agreed to participate (n=20, of which 9 with asthma) had EB collected (Tedlar® bags) before and after a swimming training session. SPME fiber (DVB/CAR/PDMS) was used to extract EB metabolites followed by a multidimensional gas chromatography analysis (GC×GC‐ToFMS). Dataset comprises eight metabolites end products of lipid peroxidation: five aliphatic alkanes (nonane, 2,2,4,6,6‐pentamethylheptane, decane, dodecane, and tetradecane) and three aldehydes (nonanal, decanal, and dodecanal). To assess exercise impact on lipid peroxidation markers, data were analyzed using principle component analysis (PCA), which was run on the original data set and on the data set constructed using differences in the metabolite total areas before and after exercise session. Results: Heatmap representation revealed that metabolites content decreased after exercise, both for control and asthma groups; however, the greater decrease was observed for controls. Asthmatics and controls did not form separated clusters; however, control swimmers demonstrated a more varied response to the exercise being dispersed along all score plot. Conclusion: In well‐trained athletes, swimming is associated with a decrease in oxidative stress markers independently of the presence of asthma, although a more pronounced decrease was seen in controls.European Regional Development Fund FEDER through the Competitive Factors Thematic Operational Programme (COMPETE) and FCT, Portugal, under projects PEST-C/QUI/UI0062/2013 (Research Unit 62/94 QOPNA) and PTDC/QUI-QUI/117803/2010

Communication in Clinical Practice, the Perspective of Patients with Cancer: Translation of the PACE (Patient Assessment of Cancer Communication Experiences) Questionnaire to European Portuguese

Introduction: Communication in clinical practice is essential to healthcare quality, especially in Oncology. The Patient Assessment of Communication Experiences questionnaire evaluates the perspective of cancer patients towards communication and identifies areas that can be improved. This study consists in its translation and validation to European Portuguese, to identify these areas. Material and methods: We performed a descriptive, observational, cross-sectional study. The translation was conducted according to the World Health Organization's guidelines. We applied the questionnaires to a convenience sample, in patients under systemic antineoplastic treatment at the Day Hospital of Centro Hospitalar Universitário do Porto, between January and March 2020. We calculated the Cronbach's Alpha for each phase of care, the bivariate and multiple correlations and, for each question, the percentage of "non applicable" and most positive answers. Results: We had 100 participants. The instrument we obtained ha good internal consistency, but the classification of some questions does not correlate sufficiently with the global opinion about the experiences with communication in the respective phase. The diagnosis phase revealed a lower proportion of positive experiences, particularly in terms of receiving the bad news. Conclusion: This study translates and validates part of the communication assessment instrument PACE to the Portuguese language and elicits the necessity to invest in the phase of diagnosis and disclosure of bad news.ste trabalho não recebeu qualquer tipo de suporte financeiro de nenhuma entidade no domínio público ou privado

Evaluation of biventricular function in the rat: a new experimental model

The use of small animals in cardiovascular research has increased over recent years. This might be a limitation when evaluation of biventricular function is required. Although evaluation of left ventricular (LV) pressure and volume is already possible in small animals, concomitant evaluation of right ventricle function has been limited to large animals. The study describes a new model to assess pressures and dimensions of both ventricles simultaneously in the adult rat. Adult Wistar rats (n = 12), weighing 372 +/- 16 g, were anesthetized with pentobarbital (60 mg/kg, i.p.) and ventilated through a tracheostomy (60 cpm, 1 ml/100 g). Under a dissecting microscope (6x) the right jugular vein was catheterized. After sternotomy and pericardiotomy, three crystals were placed along the major cardiac transverse diameter: in the right subendocardium of the interventricular septum and on the epicardial surfaces of the RV and LV free walls. In addition, two high-fidelity catheters were introduced through the apex into the RV (2F, Millar) and LV (3F, Millar) cavities. This allowed the measurement of all parameters derived from pressure and dimension curves of the RV and LV, including pressure-dimension loops. This study describes, for the first time, a model that allows simultaneous evaluation of biventricular pressure and dimensions in an animal model as small as an adult rat. This model opens up new perspectives for the establishment of correlations between molecular biology and hemodynamic data in both ventricles, which is particularly important as more differences between the two ventricles are being found

Endogenous production of ghrelin and beneficial effects of its exogenous administration in monocrotaline-induced pulmonary hypertension

We investigated the endogenous production of ghrelin as well as cardiac and pulmonary vascular effects of its administration in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). Adult Wistar rats randomly received a subcutaneous injection of MCT (60 mg/kg) or an equal volume of vehicle. One week later, animals were randomly assigned to receive a subcutaneous injection of ghrelin (100 mug/kg bid for 2 wk) or saline. Four groups were analyzed: normal rats treated with ghrelin (n = 7), normal rats injected with saline (n = 7), MCT rats treated with ghrelin (n = 9), and MCT rats injected with saline (n = 9). At 22-25 days, right ( RV) and left ventricular (LV) pressures were measured, heart and lungs were weighted, and samples were collected for histological and molecular analysis. Endogenous production of ghrelin was almost abolished in normal rats treated with ghrelin. In MCT-treated animals, pulmonary expression of ghrelin was preserved, and RV myocardial expression was increased more than 20 times. In these animals, exogenous administration of ghrelin attenuated PH, RV hypertrophy, wall thickening of peripheral pulmonary arteries, and RV diastolic disturbances and ameliorated LV dysfunction, without affecting its endogenous production. In conclusion, decreased tissular expression of ghrelin in healthy animals but not in PH animals suggests a negative feedback in the former that is lost in the latter. A selective increase of ghrelin mRNA levels in the RV of animals with PH might indicate distinct regulation of its cardiac expression. Finally, ghrelin administration attenuated MCT-induced PH, pulmonary vascular remodeling, and RV hypertrophy, indicating that it may modulate PH

Antinociception induced by chronic glucocorticoid treatment is correlated to local modulation of spinal neurotransmitter content

<p>Abstract</p> <p>Background</p> <p>While acute effects of stress on pain are well described, those produced by chronic stress are still a matter of dispute. Previously we demonstrated that chronic unpredictable stress results in antinociception in the tail-flick test, an effect that is mediated by increased levels of corticosteroids. In the present study, we evaluated nociception in rats after chronic treatment with corticosterone (CORT) and dexamethasone (DEX) in order to discriminate the role of each type of corticosteroid receptors in antinociception.</p> <p>Results</p> <p>Both experimental groups exhibited a pronounced antinociceptive effect after three weeks of treatment when compared to controls (CONT); however, at four weeks the pain threshold in CORT-treated animals returned to basal levels whereas in DEX-treated rats antinociception was maintained. In order to assess if these differences are associated with altered expression of neuropeptides involved in nociceptive transmission we evaluated the density of substance P (SP), calcitonin gene-related peptide (CGRP), somatostatin (SS) and _B2-γ-aminobutiric acid receptors (GABA_B2) expression in the spinal dorsal horn using light density measurements and stereological techniques. After three weeks of treatment the expression of CGRP in the superficial dorsal horn was significantly decreased in both CORT and DEX groups, while GABA_B2was significantly increased; the levels of SP for both experimental groups remained unchanged at this point. At 4 weeks, CGRP and SP are reduced in DEX-treated animals and GABA_B2unchanged, but all changes were restored to CONT levels in CORT-treated animals. The expression of SS remained unaltered throughout the experimental period.</p> <p>Conclusion</p> <p>These data indicate that corticosteroids modulate nociception since chronic corticosteroid treatment alters the expression of neuropeptides involved in nociceptive transmission at the spinal cord level. As previously observed in some supraspinal areas, the exclusive GR activation resulted in more profound and sustained behavioural and neurochemical changes, than the one observed with a mixed ligand of corticosteroid receptors. These results might be of relevance for the pharmacological management of certain types of chronic pain, in which corticosteroids are used as adjuvant analgesics.</p

MetaBags: Bagged Meta-Decision Trees for Regression

Ensembles are popular methods for solving practical supervised learning problems. They reduce the risk of having underperforming models in production-grade software. Although critical, methods for learning heterogeneous regression ensembles have not been proposed at large scale, whereas in classical ML literature, stacking, cascading and voting are mostly restricted to classification problems. Regression poses distinct learning challenges that may result in poor performance, even when using well established homogeneous ensemble schemas such as bagging or boosting. In this paper, we introduce MetaBags, a novel, practically useful stacking framework for regression. MetaBags is a meta-learning algorithm that learns a set of meta-decision trees designed to select one base model (i.e. expert) for each query, and focuses on inductive bias reduction. A set of meta-decision trees are learned using different types of meta-features, specially created for this purpose - to then be bagged at meta-level. This procedure is designed to learn a model with a fair bias-variance trade-off, and its improvement over base model performance is correlated with the prediction diversity of different experts on specific input space subregions. The proposed method and meta-features are designed in such a way that they enable good predictive performance even in subregions of space which are not adequately represented in the available training data. An exhaustive empirical testing of the method was performed, evaluating both generalization error and scalability of the approach on synthetic, open and real-world application datasets. The obtained results show that our method significantly outperforms existing state-of-the-art approaches

Modelling and simulating change in reforesting mountain landscapes using a social-ecological framework

Natural reforestation of European mountain landscapes raises major environmental and societal issues. With local stakeholders in the Pyrenees National Park area (France), we studied agricultural landscape colonisation by ash (Fraxinus excelsior) to enlighten its impacts on biodiversity and other landscape functions of importance for the valley socio-economics. The study comprised an integrated assessment of land-use and land-cover change (LUCC) since the 1950s, and a scenario analysis of alternative future policy. We combined knowledge and methods from landscape ecology, land change and agricultural sciences, and a set of coordinated field studies to capture interactions and feedback in the local landscape/land-use system. Our results elicited the hierarchically-nested relationships between social and ecological processes. Agricultural change played a preeminent role in the spatial and temporal patterns of LUCC. Landscape colonisation by ash at the parcel level of organisation was merely controlled by grassland management, and in fact depended on the farmer's land management at the whole-farm level. LUCC patterns at the landscape level depended to a great extent on interactions between farm household behaviours and the spatial arrangement of landholdings within the landscape mosaic. Our results stressed the need to represent the local SES function at a fine scale to adequately capture scenarios of change in landscape functions. These findings orientated our modelling choices in the building an agent-based model for LUCC simulation (SMASH - Spatialized Multi-Agent System of landscape colonization by ASH). We discuss our method and results with reference to topical issues in interdisciplinary research into the sustainability of multifunctional landscapes

Rising burden of Hepatitis C Virus in hemodialysis patients

<p>Abstract</p> <p>Aim</p> <p>High prevalence of Hepatitis C virus (HCV) has been reported among the dialysis patients throughout the world. No serious efforts were taken to investigate HCV in patients undergoing hemodialysis (HD) treatment who are at great increased risk to HCV. HCV genotypes are important in the study of epidemiology, pathogenesis and reaction to antiviral therapy. This study was performed to investigate the prevalence of active HCV infection, HCV genotypes and to assess risk factors associated with HCV genotype infection in HD patients of Khyber Pakhtunkhwa as well as comparing this prevalence data with past studies in Pakistan.</p> <p>Methods</p> <p>Polymerase chain reaction was performed for HCV RNA detection and genotyping in 384 HD patients. The data obtained was compared with available past studies from Pakistan.</p> <p>Results</p> <p>Anti HCV antibodies were observed in 112 (29.2%), of whom 90 (80.4%) were HCV RNA positive. In rest of the anti HCV negative patients, HCV RNA was detected in 16 (5.9%) patients. The dominant HCV genotypes in HCV infected HD patients were found to be 3a (n = 36), 3b (n = 20), 1a (n = 16), 2a (n = 10), 2b (n = 2), 1b (n = 4), 4a (n = 2), untypeable (n = 10) and mixed (n = 12) genotype.</p> <p>Conclusion</p> <p>This study suggesting that i) the prevalence of HCV does not differentiate between past and present infection and continued to be elevated ii) HD patients may be a risk for HCV due to the involvement of multiple routes of infections especially poor blood screening of transfused blood and low standard of dialysis procedures in Pakistan and iii) need to apply infection control practice.</p