Structure function interface with sequential shortening of basal and apical components of the myocardial band

Objective: To mechanically test the intact cardiac structure to determine the sequence of contraction within the myocardial mass to try to explain ejection and suction. Methods: In 24 pigs (30–85 kg), segment shortening at the site of sonomicrometer crystals was continuously recorded. The ECG evaluated rhythm, and Millar pressure transducers measured intraventricular pressure and dP/dt. Results: Study of segment shortening defined a sequence of contraction within the myocardial mass, starting at the free wall of the right ventricle and on the endocardial side of the antero-septal wall of the left. Crystal location defined underlying contractile trajectory; transverse in right ventricle followed by basal posterior left ventricle, and from the endocardial anterior wall to the posterior apical segment and finally to the epicardial side of the anterior wall. Mean shortening fraction averaged 18±3%, with endocardial exceeding epicardial shortening by 5±1%. Epicardial segment crystal displacement followed endocardial shortening by 82±23 ms in the anterior wall, and finished 92±33 ms after endocardial shortening stopped, time frame that matches the interval of fast drop of ventricular pressure and the start of suction. Conclusions: Crystal shortening fraction sequence followed the rope-like myocardial band model to contradict traditional thinking, with two starting points of excitation–contraction, the right anterior free wall of the right ventricle, and the endocardial side of the anterior wall. Active suction may be due to active shortening of the epicardial fibers of the anterior wall, because relaxation was not detected when both mitral and aortic valves were closed during the interval previously termed ‘isovolumetric relaxation’.     

Microstructural Evolution during Accelerated Tensile Creep Test of ZK60/SiCp Composite after KoBo Extrusion

In the current study, the creep properties of magnesium alloy reinforced with SiC particles were investigated. For this purpose, ZK60/SiCp composite was produced by the stir casting method following the KoBo extrusion and precipitation hardening processes. The creep tests were performed at 150 °C under 10–110 MPa. The results showed that the stress exponent (n) and the average true activation energy (Q) was changed at high stresses, was found with increasing stress, the creep mechanism changing from grain boundary sliding to dislocation climb. The results of microstructure characterization after the creep test showed that at low stresses, the dynamic recrystallization resulting from twinning induced the GBS mechanism. However, at high stresses, with increasing diffusion rates, conditions are provided for dynamic precipitation and the dislocation climb of the dominant creep mechanism. Examination of the fracture surfaces and the surrounding areas showed that the cavity nucleation in the ternary boundary and surrounding precipitation was the main cause of damage. The evaluation of the samples texture after creep showed that the unreinforced alloy showed a moderately strong fiber texture along the angle of ϕ₁ = 0–90°, which was tilted about Φ = 10°. A new strong texture component was observed at (90°, 5°, 0°) for the composite sample, which crept due to minor splitting of the basal pole by ~5° toward RD.     

An Improved Optimization Model to Predict the MOR of Glulam Prepared by UF-Oxidized Starch Adhesive: A Hybrid Artificial Neural Network-Modified Genetic Algorithm Optimization Approach

The purpose of the present article is to study the bending strength of glulam prepared by plane tree (Platanus Orientalis-L) wood layers adhered by UF resin with different formaldehyde to urea molar ratios containing the modified starch adhesive with different NaOCl concentrations. Artificial neural network (ANN) as a modern tool was used to predict this response, too. The multilayer perceptron (MLP) models were used to predict the modulus of rapture (MOR) and the statistics, including the determination coefficient (R²), root mean square error (RMSE), and mean absolute percentage error (MAPE) were used to validate the prediction. Combining the ANN and the genetic algorithm by using the multiple objective and nonlinear constraint functions, the optimum point was determined based on the experimental and estimated data, respectively. The characterization analysis, performed by FTIR and XRD, was used to describe the effect of the inputs on the output. The results indicated that the statistics obtained show excellent MOR predictions by the feed-forward neural network using Levenberg–Marquardt algorithms. The comparison of the optimal output of the actual values obtained by the genetic algorithm resulting from the multi-objective function and the optimal output of the values estimated by the nonlinear constraint function indicates a minimum difference between both functions.     

Subendocardial stress in pre‐eclampsia

A primigravida 26‐year‐old woman who had developed pre‐eclampsia with malignant hypertension at 30 weeks of gestation suffered acute myocardial infarction two days postpartum. Electrocardiogram demonstrated diffuse ST‐segment depression suggestive of subendocardial ischemia. Echocardiography demonstrated focal asymmetric left ventricular hypertrophy, with a characteristic “basal septal bulge”, and a left ventricular mid‐cavitary gradient of 51 mmHg. Coronary angiography revealed normal coronary arteries and vascular flow. Peripartum acute myocardial infarction is rare and portends a high mortality. However, to date, only one case of acute myocardial infarction associated with asymmetric left ventricular hypertrophy and pre‐eclampsia has been described in the literature.     

Effects of vitamin C and melatonin on cysteamine-induced duodenal ulcer in a cholestatic rat model: A controlled experimental study

Background: Superoxide dismutase (SOD) is one of the defense mechanisms against free radicals. Cysteamine is a cytotoxic agent, acting through generation of reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radical, and superoxide, and may decrease defense activity of SOD against ROS and induce duodenal ulcer. Melatonin is a suicidal antioxidant that has a protective effect against ROS and cytoprotective effect through inhibition of the decrease in SOD activity.Objectives: The primary aim of this study was to assess the effects of pretreatment with vitamin C and melatonin on cysteamine-induced duodenal ulcer. Secondary aims were to compare the ulcerogenic effect of cysteamine and the antiulcer effects of vitamin C and melatonin.Methods: This study was performed in male Wistar rats (200-250 g) in 3 groups of equal size (n = 24): bile duct ligation-induced cholestasis (test), sham, and control groups. In the test and sham groups, laparotomy was performed under general anesthesia and the common bile duct was identified; in sham rats, the common bile duct was left in situ, but in test rats, the common bile duct was isolated and doubly ligated to induce cholestasis. Animals in each group were also divided into 4 equal subgroups (n = 6). These subgroups were treated with vitamin C plus cysteamine, melatonin plus cysteamine, cysteamine alone, and saline, respectively. All animals were euthanized via overdose of ether anesthesia 24 hours after the last injection of cysteamine or saline, and 0.5 mL of blood was collected from the heart ventricle. The duodenum was cut open, washed with saline, fixed, and prepared for calculation of ulcer index (Szabo method) and histopathologic assessment. SOD activity was measured using a branded enzyme kit.Results: In all 3 groups, animals treated with cysteamine had significantly increased mean (SE) ulcer index (test, 4.00 [0.10] vs 1.17 [0.30]; sham, 3.83 [0.16] vs 0.50 [0.22]; control, 3.67 [0.21] vs 0 [0]) and decreased SOD activity (test, 146.41 [2.16] vs 299.83 [1.94] U/mL; sham, 154.75 [2.02] vs 303.08 [0.35] U/mL; control, 157.08 [1.67] vs 314.50 [1.14] U/mL) compared with saline-treated rats (all, P < 0.001). In the test rats, ulcer index was significantly increased and SOD activity was significantly decreased compared with the sham and control groups (both, P < 0.001). Pretreatment with vitamin C and melatonin was associated with attenuation of ulcer index and increased SOD activity compared with rats treated with cysteamine alone (P < 0.001). There were no significant differences in ulcer index or SOD activity between groups administered vitamin C or melatonin.Conclusions: In this experimental study, pretreatment with melatonin or vitamin C in all rats produced significant attenuation of the ulcer index and enhanced SOD activity. Cysteamine-induced duodenal mucosal damage was greater in cholestatic rats compared with sham and control rats.     

The effects of aquatic exercise on body composition and nonspecific low back pain in elderly males

[Purpose] The purpose of this study was to investigate the effect of aquatic exercises on nonspecific low back pain (LBP) in elderly males. [Subjects and Methods] Thirty-two elderly men aged 65 or older were recruited and randomly allocated to two groups: aquatic training (3 d/wk for 12 wk) or a control group. Body mass index (BMI), percentage of body fat (PBF), waist-hip ratio (WHR), and trunk muscle mass were measured before and after training. [Results] The results suggested that all obesity variables including BMI, WHR, and PBF of the aquatic training group were decreased significantly, while the trunk muscle mass of the aquatic training group was increased significantly. Furthermore, low back pain was decreased in the subjects after the intervention. [Conclusion] The water-based program improved LBP and body composition in the elderly men.Key words: Elderly, Low back pain, Body composition     

The Efficacy of an Herbal Medicine, Carmint, on the Relief of Abdominal Pain and Bloating in Patients with Irritable Bowel Syndrome: A Pilot Study

Carmint contains total extracts of Melissa officinalis, Mentha spicata, and Coriandrum sativum, which have antispasmodic, carminative, and sedative effects. As abdominal pain/discomfort and bloating are commonly observed in patients with irritable bowel syndrome, we decided to evaluate the effectiveness of Carmint in relieving these symptoms in irritable bowel syndrome patients. We randomly assigned 32 irritable bowel syndrome patients to receive either Carmint or placebo, plus Loperamide or psyllium (based on their predominant bowel function), for 8 weeks. T-test analysis of the results showed that the severity and frequency of abdominal pain/discomfort were significantly lower in the Carmint group than the placebo group at the end of the treatment (P=0.016 and P=0.001, respectively), as were the severity and frequency of bloating (P=0.02 and P=0.002, respectively). This pilot study suggests that Carmint plus loperamide or Carmint plus psyllium (depending on the irritable bowel syndrome subtype) might be effective in these patients.