Construction and validation of a risk prediction model for postoperative delirium in patients with off­pump coronary artery bypass grafting.

Background: Compared with cardiopulmonary bypass surgery, off-pump coronary artery bypass grafting (OPCABG) reduces trauma to the body. However, there is still a risk of neurological complications, including postoperative delirium (POD). To date, few studies have been conducted on the risk of POD in OPCABG patients, and no standardized prediction model has been established. Thus, this study sought to analyze the factors influencing POD in OPCABG patients and to construct a risk prediction model. Methods: A total of 1,258 patients with OPCABG were enrolled and divided into the training set for model construction (944 cases) and the test set for model validation (314 cases). A risk prediction model for POD in OPCABG patients was established by least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression, and a nomogram was drawn. The discrimination and calibration degree of the model was evaluated by the receiver operator characteristic (ROC) curve and calibration curve. Results: Eight variables [i.e., age, tissue oxygen saturation, mean arterial pressure (MAP), carotid stenosis, the anterior-posterior diameter of the aortic sinus, ventricular septum thickness, left ventricular ejection fraction (LVEF), and Mini-Mental State Examination (MMSE) scores] were screen out by the LASSO regression and multivariate logistic regression, and the model was constructed. The area under the ROC curve of the training set was 0.702 [95% confidence interval (CI): 0.662-0.743], and that of the test set was 0.658 (95% CI: 0.585-0.730). The results of the Hosmer-Lemeshow goodness-of-fit test showed that the predicted POD risk of OPCABG patients in the training and test sets was consistent with the actual POD risk (χ2=5.154, P=0.74). Conclusions: The occurrence of POD in OPCABG patients is related to age, tissue oxygen saturation, MAP, carotid artery stenosis, the anterior-posterior diameter of aortic sinus, ventricular septal thickness, LVEF, and MMSE scores. The prediction model constructed with the above variables had high predictive performance, and thus may be helpful in the early identification of such patients.

Influence of the Unit Cell Parameters on the Thermomechanical Non-Symmetric In-Plane Shear Behavior of 2D Biaxial Braided Preform for Thermoplastic Biocomposites.

The identification of thermomechanical in-plane shear behavior of preform is one of the most important factors to ensure the quality of the thermoplastic composites during the thermoforming process. In this present work, the non-symmetric in-plane shear behavior of flax/polypropylene 2D biaxial braided preform for thermoplastic biocomposites was characterized at elevated temperature chamber by using bias-extension test. Analytical models of a bias-extension test based on non-symmetric unit cell geometry for 2D biaxial braids were defined and applied; the thermo-condition-dependent experiments were conducted to study the temperature and displacement rate dependences. The influence of unit cell geometry parameters including braiding angle, tow waviness, and cover factor on the thermal in-plane shear behavior was deeply invested, experiments in both axial and transversal directions were performed for a complete study, and asymmetric scissor mechanisms for in-plane shear behavior were introduced and studied. Finally, a simulation of thermal impregnation distribution based on unit cell geometry was made to clarify the importance of the overall fiber volume fraction.

Sevoflurane prevents pulmonary vascular remodeling and right ventricular dysfunction in pulmonary arterial hypertension in rats.

BACKGROUND: The cardioprotective properties of sevoflurane have been reported in studies of the left ventricle. However, whether this volatile anesthetic would also be beneficial for pulmonary vascular remodeling and associated right ventricular hypertrophy (RVH) remained to be explored. Here, we investigated the potential benefit of sevoflurane to right heart function in experimental pulmonary arterial hypertension (PAH). METHODS: Adult Wistar rats received one dose peritoneal injection of monocrotaline (MCT, 60 mg/kg) or the equal volume of normal saline. Two weeks later, rats were treated with sevoflurane or sham exposure. PAH status and cardiac function were assessed by echocardiography weekly, and the body weight (BW) was monitored every week. After 6 weeks of exercise, Fulton's index calculation, histological observation, IL-6 and TNF-α immunohistochemical analyses, evaluation of MDA, SOD and GSH-Px levels and NF-κB and MAPK active determination were performed in lung and RV tissue samples. RESULTS: MCT induced pulmonary vascular remodeling, RVH, increased Fulton's index (P<0.01), and right ventricular failure (RVF) in rats. Animals inhaled sevoflurane had an increased cardiac output (P<0.05) and lower incidence of RVF (P<0.05). Also, these animals had a reduced RVEDD, RVWTd and PAID (P<0.05), increased PV (P<0.05), reduced wall thickness and vascular wall area of pulmonary small vascular (vascular external diameter 50-150 um) (P<0.01), reduced RV fibrosis, and increased RV cardiomyocyte area (P<0.01). Furthermore, sevoflurane reduced IL-6 and TNF-α expression in lungs and heart (P<0.01), decreased level of MDA (P<0.01) and increased activity of SOD and GSH-Px (P<0.01). In addition, it decreased the activities of NF-κB and MAPK pathways (P<0.01). CONCLUSION: Sevoflurane reduces pulmonary vascular remodeling and RVH in PAH induced by MCT in rats. This effect is likely due to down-regulation of inflammatory factors IL-6 and TNF-α, reduced level of oxidative stress and the inhibition of NF-κB and MAPK pathways.

Resistin-Like Molecule α Dysregulates Cardiac Bioenergetics in Neonatal Rat Cardiomyocytes.

Heart (right) failure is the most frequent cause of death in patients with pulmonary arterial hypertension. Although historically, increased right ventricular afterload has been considered the main contributor to right heart failure in such patients, recent evidence has suggested a potential role of load-independent factors. Here, we tested the hypothesis that resistin-like molecule α (RELMα), which has been implicated in the pathogenesis of vascular remodeling in pulmonary artery hypertension, also contributes to cardiac metabolic remodeling, leading to heart failure. Recombinant RELMα (rRELMα) was generated via a Tet-On expression system in the T-REx 293 cell line. Cultured neonatal rat cardiomyocytes were treated with purified rRELMα for 24 h at a dose of 50 nM. Treated cardiomyocytes exhibited decreased mRNA and protein expression of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) and transcription factors PPARα and ERRα, which regulate mitochondrial fatty acid metabolism, whereas genes that encode for glycolysis-related proteins were significantly upregulated. Cardiomyocytes treated with rRELMα also exhibited a decreased basal respiration, maximal respiration, spare respiratory capacity, ATP-linked OCR, and increased glycolysis, as assessed with a microplate-based cellular respirometry apparatus. Transmission electron microscopy revealed abnormal mitochondrial ultrastructure in cardiomyocytes treated with rRELMα. Our data indicate that RELMα affects cardiac energy metabolism and mitochondrial structure, biogenesis, and function by downregulating the expression of the PGC-1α/PPARα/ERRα axis.

Effects of Micro-Braiding and Co-Wrapping Techniques on Characteristics of Flax/Polypropylene-Based Hybrid Yarn: A Comparative Study.

Micro-braiding and co-wrapping techniques have been developed over a few decades and have made important contributions to biocomposites development. In this present study, a set of flax/polypropylene (PP) micro-braided and co-wrapped yarns was developed by varying different PP parameters (PP braiding angles and PP wrapping turns, respectively) to get different flax/PP mass ratios. The effects on textile and mechanical characteristics were studied thoroughly at the yarn scale, both dry- and thermo-state tensile tests were carried out, and tensile properties were compared before and after the braiding process to study the braidabilities. It was observed that PP braiding angles of micro-braided yarn influenced the frictional damage on surface treatment agent of flax roving, the cohesive effect between PP filaments/flax roving, and the PP cover factor; PP wrapping turns of co-wrapped yarn had a strong impact on the flax roving damage and the PP coverage, which further influenced the characteristics. Micro-braided yarn and co-wrapped yarn with the same flax/PP mass ratio were compared to evaluate the two different hybrid yarn production techniques; it was proven that micro-braided yarn presented better performance.

Effect of dexmedetomidine on hemodynamic changes and inflammatory responses in patients undergoing off-pump coronary-artery bypass grafting.

The aim of the present study was to determine the effect of dexmedetomidine on hemodynamic changes and inflammatory responses in patients undergoing off-pump coronary artery bypass grafting (OPCABG). A total of 300 patients about to receive OPCABG were randomized evenly into the control group (n=116) and study group (n=123). Intravenous dexmedetomidine pump infusion was administered to patients in the study group at a rate of 0.4 µg.kg-1.h-1. The control group received physiological saline at the same infusion speed. Changes in hemodynamic parameters and inflammatory indices were compared between the two groups. Hemodynamic parameters, such as the heart rate and mean arterial pressure, were lower in patients from the study group, compared with that in the control group (both P<0.05). The levels of pro-inflammatory factors, such as interleukin (IL)-6, tumor necrosis factor-α and C-reactive protein, were also reduced in the study group (P<0.05). The observed levels of IL-10 were lower in the control group compared with that in the study group, although a statistically significant difference was not achieved. Thus, the administration of dexmedetomidine in patients undergoing OPCABG stabilized hemodynamics and reduced inflammation. The present study was registered at the Chinese Clinical Trial Registry, under the trial registration number ChiCTR-OOC-15005978 (2015).