An improvement in the method of correcting indirect radial strain measurements during triaxial strength tests in rocks.

The present article provides an improvement in the method to correct indirect strain measurements in triaxial compressive strength tests through axial displacement and hydraulic fluid volume change measurements. The improvement focused on reducing the parameters of the formula proposed for indirect volumetric strain in the original method, thereby facilitating the development of a simpler formula in which the radial strain depends on only two parameters: the initial volume of the rock specimen and the volume changes of the hydraulic fluid for each instant. The comparison between the improvement proposed, and original method resulted in a mean absolute difference of 0.003.•This improvement does not depend on the axial strain, unlike the original method, which requires correcting the indirect axial strain measurements before correcting the indirect radial strain measurements.•This improvement can be useful for research on the stress-strain behavior of intact rock under laboratory conditions, such as in the study of the post-peak state.

Doxorubicin cardiotoxicity and Camellia sinensis cardioprotection determined by speckle-tracking echocardiography

Abstract Doxorubicin (Dox) is a medication used in the treatment of cancerous tumors and hematologic malignancies with potentially serious side effects, including the risk of cardiotoxicity. Flavonoids are plant metabolites with antioxidant properties and can be extracted from Camellia sinensis (CS). The aim of this study is to evaluate the possible cardioprotective effect of CS against injuries induced by Dox in rats. A total of 32 animals were distributed into four groups: (1) control - intraperitoneal injection (I.P.) of 0.5 mL saline weekly and 1.0 mL water by gavage daily; (2) CS - 0.5 mL saline I.P. weekly and 200 mg/kg CS by gavage daily; (3) Dox - 5.0 mg/kg Dox I.P. weekly and 1.0 mL water by gavage daily; and (4) Dox+CS -5.0 mg/kg Dox I.P. weekly and 200 mg/kg CS by gavage daily. Clinical examinations, blood profiles, electrocardiograms, echocardiograms, and histological analyses of hearts were performed over 25 days. The animals in the Dox group showed changes in body weight and in erythrogram, leukogram, electrocardiography, and echocardiography readings. However, animals from the dox+CS group had significantly less change in body weight, improved cardiac function, and showed more preserved cardiac tissue. This study demonstrated that CS prevents dox-induced cardiotoxicity, despite enhancing the cytotoxic effect on blood cells

Imposition of Fontan physiology: Effects on strain and global measures of ventricular function.

OBJECTIVE: We sought to evaluate contractile function in single-ventricle patients before and after imposition of Fontan physiology. METHODS: Single right ventricle (SRV; n = 38) and single left ventricle (SLV; n = 11) patients underwent cardiac magnetic resonance imaging pre and post Fontan operation. Global radial strain (GRS), global circumferential strain (GCS), and global longitudinal strain were measured along with ejection fraction (EF) and atrioventricular valve regurgitation (AVVR). RESULTS: Age at cardiac magnetic resonance imaging before the Fontan operation was 3.1 ± 1.3 years and after the Fontan procedure was 5.8 ± 2.7 years. There were no significant EF differences between SRV and SLV patients before and after the Fontan procedure, and EF did not deteriorate significantly after the Fontan operation. GRS was significantly lower for SRV patients than for SLV patients before (24.3% vs 32.1%; P = .048) and after (21.8% vs 29.7%; P = .045) the Fontan procedure. GRS and GCS of the SRV patients deteriorated significantly after the Fontan operation (GRS, P = .01; GCS, P = .009). Strains showed positive correlations before and after the Fontan operation with positive correlations among each strain. Within all patients, strains correlated positively with EF. Strains and EF negatively correlated with AVVR (GRS P = .03, r = -0.22; GCS P = .03, r = -0.23; EF P < .001, r = -0.37). CONCLUSIONS: Strains were lower for SRV than for SLV patients before and after the Fontan operation and deteriorated after the Fontan operation. Our study suggests that strain measures might detect ventricular deterioration earlier than EF. Because strains before and after the Fontan operation were positively correlated, and negatively correlated with AVVR, the early institution of myocardial protective therapy including AVVR management, especially for SRV patients, might have benefit.

Deformação miocárdica radial por meio do speckle tracking bidimensional em suínos com hipertensão pulmonar induzida e tratados com angiotensina-(1-7) / Evaluation of myocardial radial deformation by bidimensional speckle tracking in pigs with pulmonary hypertension treated with angiotensin- (1-7)

Pulmonary arterial hypertension (PAH) is a complex disease characterized by endothelial dysfunction resulting in pulmonary vascular remodeling, increased pulmonary arterial pressure, with subsequent right heart failure. The two-dimensional speckle tracking (2D-STE) is one of the newer tools used for early assessment of ventricular function. The aim of this study was to evaluate the radial myocardial deformation (St and StR) of LV in experimental pigs with induced PAH and treated with Ang- (1-7), checking the possibilities of this new drug in clinical and hemodynamic response, since it has anti-inflammatory effects and antiproliferative actions on the cardiovascular system. In this study we observed that animals treated with Ang (1-7) had radial St and StR higher than the placebo group at 60 days of the experiment demonstrating an improvement in systolic function of the myocardium by increased myocardial deformation (16.06±7.50 - placebo; 25.14±14.91 - Ang (1-7)) and StR (1.28±0.51 - placebo; 1.51±0.58 - Ang (1-7)). This improvement in systolic function can be attributed to drug effects while also reducing the development of pulmonary hypertension. Based on the results it is believed that Ang (1-7) may be a promising drug for the treatment of PAH.(AU)

A hipertensão arterial pulmonar (HAP) é uma doença complexa, caracterizada por disfunção endotelial, que resulta em remodelamento vascular pulmonar e elevação da pressão arterial pulmonar, com consequente insuficiência cardíaca direita. O speckle tracking bidimensional (2D-STE) é uma das mais recentes ferramentas da ecocardiografia, o qual tem sido empregado para avaliação mais precoce da função ventricular e do efeito da HAP sobre a função dos ventrículos esquerdo e direito. O objetivo deste estudo foi avaliar a deformação (St e StR) miocárdica radial do VE em modelo experimental de suínos com HAP induzida e tratados com angiotensina-(1-7), a fim de verificar as possibilidades desse novo fármaco nas respostas clínica e hemodinâmica, pois apresenta efeitos anti-inflamatório e vasodilatador, bem como ações antiproliferativas no sistema cardiovascular. Neste estudo, foi possível observar que os animais tratados com Ang-(1-7) apresentaram St e StR radiais maiores que o grupo placebo aos 60 dias de experimento, demonstrando uma melhora na função sistólica do miocárdio pelo aumento da deformação miocárdica (16,06±7,50 - placebo; 25,14±14,91 - Ang-(1-7)) e StR (1,28±0,51 - placebo; 1,51±0,58 - Ang-(1-7)). Essa melhora na função sistólica pode ser atribuída aos efeitos do fármaco, que reduziram também o desenvolvimento da hipertensão pulmonar. Diante dos resultados, acredita-se que a Ang-(1-7) possa ser um medicamento promissor para tratamento da HAP.(AU)