Ventricular endocardial tissue geometry affects stimulus threshold and effective refractory period

Background: Understanding the biophysical processes by which electrical stimuli applied to cardiac tissue may result in local activation is important in both the experimental and clinical electrophysiology laboratory environments, as well as for gaining a more in-depth knowledge of the mechanisms of focal-trigger-induced arrhythmias. Previous computational models have predicted that local myocardial tissue architecture alone may significantly modulate tissue excitability, affecting both the local stimulus current required to excite the tissue and the local effective refractory period (ERP). In this work, we present experimental validation of this structural modulation of local tissue excitability on the endocardial tissue surface, use computational models to provide mechanistic understanding of this phenomena in relation to localized changes in electrotonic loading, and demonstrate its implications for the capture of afterdepolarizations. Methods and Results: Experiments on rabbit ventricular wedge preparations showed that endocardial ridges (surfaces of negative mean curvature) had a stimulus capture threshold that was 0.21 ± 0.03 V less than endocardial grooves (surfaces of positive mean curvature) for pairwise comparison (24% reduction, corresponding to 56.2 ± 6.4% of the energy). When stimulated at the minimal stimulus strength for capture, ridge locations showed a shorter ERP than grooves (n = 6, mean pairwise difference 7.4 ± 4.2 ms). When each site was stimulated with identical-strength stimuli, the difference in ERP was further increased (mean pairwise difference 15.8 ± 5.3 ms). Computational bidomain models of highly idealized cylindrical endocardial structures qualitatively agreed with these findings, showing that such changes in excitability are driven by structural modulation in electrotonic loading, quantifying this relationship as a function of surface curvature. Simulations further showed that capture of delayed afterdepolarizations was more likely in trabecular ridges than grooves, driven by this difference in loading. Conclusions: We have demonstrated experimentally and explained mechanistically in computer simulations that the ability to capture tissue on the endocardial surface depends upon the local tissue architecture. These findings have important implications for deepening our understanding of excitability differences related to anatomical structure during stimulus application that may have important applications in the translation of novel experimental optogenetics pacing strategies. The uncovered preferential vulnerability to capture of afterdepolarizations of endocardial ridges, compared to grooves, provides important insight for understanding the mechanisms of focal-trigger-induced arrhythmias

Reliability and validity of the geriatric depression scale in a sample of portuguese older adults with mild-to-moderate cognitive impairment

Although the Geriatric Depression Scale (GDS) is a well-established instrument for the assessment of depressive symptoms in older adults, this has not been validated specifically for Portuguese older adults with cognitive impairment. The objective of this study was to analyze the psychometric properties of two Portuguese versions of the GDS (GDS-27 and GDS-15) in a sample of Portuguese older adults with mild-to-moderate cognitive impairment. Clinicians assessed for major depressive disorder and cognitive functioning in 117 participants with mild-to-moderate cognitive decline (76.9% female, Mage = 83.66 years). The internal consistency of GDS-27 and GDS-15 were 0.874 and 0.812, respectively. There was a significant correlation between GDS-27 and GDS- 15 with the Beck Depression Inventory-II (GDS-27: rho = 0.738, p < 0.001; GDS-15: rho = 0.760, p < 0.001), suggesting good validity. A cutoff point of 15/16 in GDS-27 and 8/9 in GDS-15 resulted in the identification of persons with depression (GDS-27: sensitivity 100%, specificity 63%; GDS-15: sensitivity 90%, specificity 62%). Overall, the GDS-27 and GDS-15 are reliable and valid instruments for the assessment of depression in Portuguese-speaking older adults with cognitive impairmentS

Pretratamiento con hialuronidasa mejora la tinción de colágeno en notocorda de esturión

Objective: The current study aimed to design a histological method to determine the presence and organization of the collagen network in sturgeon notochord. Methods: Serial sections of sturgeon notochord (Acipenser naccarii) were used and assigned to two different experimental groups: Hyaluronidase pre-treatment (HP) in an alcohol acid solution (1% HCl in 70% alcohol solution) for 15 min and hyaluronidase solution in a 2 µg/ ml concentration (pre-heated at 37º C), and control (CTR) group, without pre-treatment. Then, the ECM was assessed by two histochemical methods: Picrosirius Red (PR) staining for 30 min with Sirius red (0.1% of Sirius red in saturated aqueous picric acid), for collagen bundle staining, and Alcian Blue (AB) staining for glycosaminoglycans detection. Results: Samples analyzed in this study showed positive histochemical reaction for collagen fibers in both experimental groups. Referring to PR staining, the CTR group presented a larger and homogeneous reaction was observed in the entire samples, whereas HP group presented a more definite and intense pattern of collagen network. Also, this more intense signal in HP group matched with an increase of birefringence in polarized microscopy images of PR. However, HP group showed a lower intense and more heterogeneous signal when was compared with CTR group in AB staining. Conclusion: Using a simple histological example, our study illustrates the capability of a hyaluronidase pre-treatment to enhance picrosirius red staining in sturgeon notochord trough light and polarized microscopy.Objetivo: El presente estudio tiene por objetivo diseñar un método histológico para determinar la presencia y organización de la red de colágeno en la notocorda del esturión. Métodos: Secciones seriada de la notocorda de esturión (Acipenser naccarii) fueron utilizadas y se asignaron a dos grupos experimentales diferentes: pretratamiento de hialuronidasa (HP) en una solución de alcohol ácido (HCl al 1% en solución de alcohol al 70%) durante 15 minutos y posteriormente a una solución de hialuronidasa en una concentración de 2 μg / ml (precalentada a 37º C) y grupo de control (CTR), sin tratamiento previo. Luego, la ECM se evaluó mediante dos métodos histoquímicos: tinción Picrosirius Red (PR) durante 30 minutos con rojo Sirio (0,1% de rojo Sirio en una solución saturada de ácido pícrico), para la tinción de colágeno; y tinción con Alcian Blue (AB) para detección de glicosaminoglicanos. Resultados: Las muestras analizadas en este estudio mostraron una reacción histoquímica positiva para las fibras de colágeno en ambos grupos experimentales. Con respecto a la tinción PR, el grupo CTR presentó una reacción mayor y más homogénea en toda la superficie de las muestras, mientras que el grupo HP presentó un patrón red de colágeno más definido e intenso. Además, esta señal más intensa en el grupo HP coincidió con un aumento de la birrefringencia en las imágenes de microscopía polarizada de PR. Sin embargo, el grupo HP mostró una señal menos intensa y más heterogénea cuando se comparó con el grupo CTR en la tinción AB. Conclusión: Utilizando un ejemplo histológico simple, nuestro estudio ilustra la capacidad de un pretratamiento de hialuronidasa para mejorar la tinción de picrosirius en la notocorda del esturión a través de la luz y la microscopía polarizada

Critical appraisal of systematic reviews of intervention studies in periodontology using AMSTAR 2 and ROBIS tools

Systematic reviews of intervention studies are used to support treatment recommendations. The aim of this study was to assess the methodological quality and risk of bias of systematic reviews of intervention studies in in the field of periodontology using AMSTAR 2 and ROBIS.Systematic reviews of randomized and non-randomized clinical trials, published between 2019 and 2020, were searched at MedLine, Embase, Web of Science, Scopus, Cochrane Library, LILACS with no language restrictions between October 2019 to October 2020. Additionally, grey literature and hand search was performed. Paired independent reviewers screened studies, extracted data and assessed the methodological quality and risk of bias through the AMSTAR 2 and ROBIS tools.One hundred twenty-seven reviews were included. According to AMSTAR 2, the methodological quality was mainly critically low (64.6%) and low (24.4%), followed by moderate (0.8%) and high (10.2%). According to ROBIS, 90.6% were at high risk of bias, followed by 7.1% low, and 2.4% unclear risk of bias. The risk of bias decreased with the increased in the impact factor of the journal.Current systematic reviews of intervention studies in periodontics were classified as low or critically low methodological quality and high risk of bias. Both tools led to similar conclusions. Better adherence to established reporting guidelines and stricter research practices when conducting systematic reviews are needed

Antibacterial activity of a new monocarbonyl analog of curcumin MAC 4 is associated with divisome disruption

Curcumin (CUR) is a symmetrical dicarbonyl compound with antibacterial activity. On the other hand, pharmacokinetic and chemical stability limitations hinder its therapeutic application. Monocarbonyl analogs of curcumin (MACs) have been shown to overcome these barriers. We synthesized and investigated the antibacterial activity of a series of unsymmetrical MACs derived from acetone against Mycobacterium tuberculosis and Gram-negative and Gram-positive species. Phenolic MACs 4, 6 and 8 showed a broad spectrum and potent activity, mainly against M. tuberculosis, Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA), with MIC (minimum inhibitory concentration) values ranging from 0.9 to 15.6 µg/mL. The investigation regarding toxicity on human lung cells (MRC-5 and A549 lines) revealed MAC 4 was more selective than MACs 6 and 8, with SI (selectivity index) values ranging from 5.4 to 15.6. In addition, MAC 4 did not demonstrate genotoxic effects on A549 cells and it was more stable than CUR in phosphate buffer (pH 7.4) for 24 h at 37 °C. Fluorescence and phase contrast microscopies indicated that MAC 4 has the ability to disrupt the divisome of Bacillus subtilis without damaging its cytoplasmic membrane. However, biochemical investigations demonstrated that MAC 4 did not affect the GTPase activity of B. subtilis FtsZ, which is the main constituent of the bacterial divisome. These results corroborated that MAC 4 is a promising antitubercular and antibacterial agent

Perceptual analysis of heterogeneous stakeholders on the impact of the Rio 2016 games in the territory of Lagoa Rodrigo de Freitas

Highlights: Development of partnership with local entities for integrated social actions; Actions and projects are developed as close as possible to the public audience; Participation in meetings and community councils; Establishment of constant dialog between social management and community leaders; Dialog with public entities; Work communication with all the impacts caused by the implementation of the megaproject, according to the affected area. Goal: Analyze, through a case study, what were the effects resulting from the Rio 2016 Olympic Games in the territory of Lagoa Rodrigo de Freitas, and how they were perceived by the stakeholders during and after the performance. Design / Methodology / Approach: On-site open and participant observation, semi-structured interviews, and on-site questionnaires and descriptive statistics Results: A series of consequences were triggered, affecting each of the different stakeholders in different ways. Limitations of the investigation: Megaprojects promote mutually positive and negative impacts concerning the local stakeholders and their multiple and different perceptions. Thus, results cannot be generalized. Practical implications: Fragmentation of the megaproject, heterogeneity, and perceptions of different stakeholders Originality / Value: Practices that are sensitive to the stakeholders’ engagement and impacts perceived

Shade and Altitude Implications on the Physical and Chemical Attributes of Green Coffee Beans from Gorongosa Mountain, Mozambique

Coffea arabica L. is as a tropical crop that can be grown under monocrop or agroforestry (AFS) systems, usually at altitudes greater than 600 m, with suitable environmental conditions to bean quality. This study aimed to assess the effect of altitude (650, 825, and 935 m) and light conditions (deep shade—DS, and moderate shade—MS provided by native trees, and full Sun—FS) on the physical and chemical attributes of green coffee beans produced in the Gorongosa Mountain. Regardless of altitude, light conditions (mainly MS and FS) scarcely affected most of the studied physical and chemical attributes. Among the few exceptions in physical attributes, bean mass tended to lower values under FS in all three altitudes, whereas bean density increased under FS at 650 m. As regards the chemical compound contents, sporadic changes were found. The rises in trigonelline (MS and FS at 935 m), soluble sugars (FS at 935 m), and the decline in p-coumaric acid (MS and FS at 825 m), may indicate an improved sensory profile, but the rise in FQAs (FS at 825 m) could have a negative impact. These results highlight a relevant uncertainty of the quality changes of the obtained bean. Altitude (from 650 to 935 m) extended the fruit maturation period by four weeks, and altered a larger number of bean attributes. Among physical traits, the average sieve (consistent tendency), bean commercial homogeneity, mass, and density increased at 935 m, whereas the bean became less yellowish and brighter at 825 and 935 m (b*, C* colour attributes), pointing to good bean trade quality, usually as compared with beans from 650 m. Furthermore, at 935 m trigonelline and 5-CQA (MS and FS) increased, whereas FQAs and diCQAs isomers declined (in all light conditions). Altogether, these changes likely contributed to improve the sensory cup quality. Caffeine and p-coumaric acid showed mostly inconsistent variations. Overall, light conditions (FS, MS, or DS) did not greatly and consistently altered bean physical and chemical attributes, whereas altitude (likely associated with lower temperature, greater water availability (rainfall/fog), and extended maturation period) was a major driver for bean changes and improved qualityinfo:eu-repo/semantics/publishedVersio

Calidad del suelo en huertos de cítricos ecológicos

El mantenimiento de la fertilidad del suelo contemplada globalmente en los aspectos físicos, químicos y biológicos es un factor clave en el sistema de producción ecológica. De ahí que en este sistema agrario se ponga un particular énfasis en la fertilización orgánica. En este estudio se comparan los resultados de varios indicadores de la calidad del suelo registrados en un grupo de 21 parcelas de cítricos ecológicos y otras tantas convencionales. La fertilidad del suelo en los huertos ecológicos resultó superior a la obtenida en los convencionales. Las actividades enzimáticas (fosfatasa alcalina y deshidrogenasa) se revelaron interesantes indicadores de los cambios a corto plazo de la calidad del suelo. La introducción de prácticas de fertilización ecológica con reducción en las aportaciones de insumos no afectó de forma significativa al estado nutritivo de los huertos de cítricos evaluados mediante análisis foliar. El sistema ecológico tampoco afectó de forma significativa al nivel de micorrización ni a las poblaciones de nematodos y hongos nematófagos