Cardiac abnormalities after induction of endoplasmic reticulum stress are associated with mitochondrial dysfunction and connexin43 expression

The endoplasmic reticulum (ER) is responsible for protein synthesis and calcium storage. ER stress, reflected by protein unfolding and calcium handling abnormalities, has been studied as a pathogenic factor in cardiovascular diseases. The aim of this study is to examine the effects of ER stress on mechanical and electrophysiological functions in the heart and explore the underlying molecular mechanisms. A total of 30 rats were randomly divided into control, ER stress inducer (tunicamycin[TN]) and ER stress inhibitor (tunicamycin+4-phenylbutyric acid [4-PBA]) groups. ER stress induction led to significantly systolic and diastolic dysfunction as reflected by maximal increasing/decreasing rate of left intraventricular pressure (±dp/dt), left ventricular peaksystolic pressure(LVSP) and LV end-diastolic pressure(LVEDP). Epicardial mapping performed in vivo revealed reduced conduction velocity and increased conduction heterogeneity associated with the development of spontaneous ventricular tachycardia. Masson’s trichrome staining revealed marked fibrosis in the myocardial interstitial and sub-pericardial regions, and thickened epicardium. Western blot analysis revealed increased pro-fibrotic factor transforming growth factor-β1 (TGF-β1), decreased mitochondrial biogenesis protein peroxlsome proliferator-activated receptor-γ coactlvator-1α （PGC-1a）, and decreased mitochondrial fusion protein mitofusin-2 (MFN2). These changes were associated with mitochondria dysfunction and connexin 43(CX43)translocation to mitochondria. These abnormalities can be partially prevented by the ER stress inhibitor 4-PBA. Our study shows that ER stress induction can produce cardiac electrical and mechanism dysfunction as well as structural remodelling. Mitochondrial function alterations are contributed by CX43 transposition to mitochondria. These abnormalities can be partially prevented by the ER stress inhibitor 4-PBA

NADPH oxidase mediates oxidative stress and ventricular remodeling through SIRT3/FOXO3a pathway in diabetic mice

Oxidative stress and mitochondrial dysfunction are important mechanisms of ventricular remodeling, predisposed to the development of diabetic cardiomyopathy (DCM) in type 2 diabetes mellitus. In this study, we have successfully established a model of type 2 diabetes using a high-fat diet (HFD) in combination with streptozotocin (STZ). The mice were divided into three groups of six at random: control, diabetes, and diabetes with apocynin and the H9c2 cell line was used as an in vitro model for investigation. We examined the molecular mechanisms of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation on mitochondrial dysfunction and ventricular remodeling in the diabetic mouse model. Hyperglycemia-induced oxidative stress led to a reduced expression of sirtuin 3 (SIRT3), thereby promoting forkhead box class O 3a (FOXO3a) acetylation in ventricular tissue and H9c2 cells. Reactive oxygen species (ROS) overproduction promoted ventricular structural modeling and conduction defects. These alterations were mitigated by inhibiting NADPH oxidase with the pharmaceutical drug apocynin (APO). Apocynin improved SIRT3 and Mn-SOD expression in H9c2 cells transfected with SIRT3 siRNA. In our diabetic mouse model, apocynin improved myocardial mitochondrial function and ROS overproduction through the recovery of the SIRT3/FOXO3a pathway, thereby reducing ventricular remodeling and the incidence of DCM

Circulating Vitamin D Concentrations and Risk of Atrial Fibrillation:A Mendelian Randomization Study Using Non-deficient Range Summary Statistics

Vitamin D deficiency is a common disorder and has been linked with atrial fibrillation (AF) in several observational studies, although the causal relationships remain unclear. We conducted a Mendelian randomization (MR) analysis to determine the causal association between serum 25-hydroxyvitamin D [25(OH)D] concentrations and AF. The analyses were performed using summary statistics obtained for single-nucleotide polymorphisms (SNPs) identified from large genome-wide association meta-analyses conducted on serum 25(OH)D ( = 79,366) and AF ( = 1,030,836). Six SNPs related to serum 25(OH)D were used as instrumental variables. The association between 25(OH)D and AF was estimated using both the fixed-effect and random-effects inverse variance weighted (IVW) method. The MR analyses found no evidence to support a causal association between circulating 25(OH)D level and risk of AF using random-effects IVW (odds ratio per unit increase in log 25(OH)D = 1.003, 95% CI, 0.841-1.196; = 0.976) or fixed-effect IVW method (OR = 1.003, 95% CI, 0.876-1.148; = 0.968). Sensitivity analyses yielded similar results. No heterogeneity and directional pleiotropy were detected. Using summary statistics, this MR study suggests that genetically predicted circulating vitamin D concentrations, especially for a non-deficient range, were not causally associated with AF in the general population. Future studies using non-linear design and focusing on the vitamin D deficiency population are needed to further evaluate the causal effect of vitamin D concentrations on AF

Plasma-Catalytic CO₂ Hydrogenation over a Pd/ZnO Catalyst: <i>In Situ</i> Probing of Gas-Phase and Surface Reactions

Plasma-catalytic CO2 hydrogenation is a complex chemical process combining plasma-assisted gas-phase and surface reactions. Herein, we investigated CO2 hydrogenation over Pd/ZnO and ZnO in a tubular dielectric barrier discharge (DBD) reactor at ambient pressure. Compared to the CO2 hydrogenation using Plasma Only or Plasma + ZnO, placing Pd/ZnO in the DBD almost doubled the conversion of CO2 (36.7%) and CO yield (35.5%). The reaction pathways in the plasma-enhanced catalytic hydrogenation of CO2 were investigated by in situ Fourier transform infrared (FTIR) spectroscopy using a novel integrated in situ DBD/FTIR gas cell reactor, combined with online mass spectrometry (MS) analysis, kinetic analysis, and emission spectroscopic measurements. In plasma CO2 hydrogenation over Pd/ZnO, the hydrogenation of adsorbed surface CO2 on Pd/ZnO is the dominant reaction route for the enhanced CO2 conversion, which can be ascribed to the generation of a ZnO x overlay as a result of the strong metal-support interactions (SMSI) at the Pd-ZnO interface and the presence of abundant H species at the surface of Pd/ZnO; however, this important surface reaction can be limited in the Plasma + ZnO system due to a lack of active H species present on the ZnO surface and the absence of the SMSI. Instead, CO2 splitting to CO, both in the plasma gas phase and on the surface of ZnO, is believed to make an important contribution to the conversion of CO2 in the Plasma + ZnO system

Application of Heat Treatment for Coloration and Hairiness Reduction of Wool Yarns

Novel water and dye-free heat treatment method was used to color wool yarn. The heat treatment can not only give the white wool yarn new color but also minimize the yarn hairiness. The influences of heating treatment temperature and time on the wool yarn color were investigated. The microstructure, twist, hairiness, wear resistance, moisture regain and tensile strength of the wool yarn were evaluated to analyze the physical and mechanical properties changes after heat treatment. The results showed that the color strength of wool yarn increased with increasing the heat treatment temperature and time. The hairs equal to or longer than 3 mm reduced significantly after heat treatment. The microstructural structure has no significant change after heat treatment, the unique overlapping scales structure on the surface still observed clearly by the SEM. The tensile strength and wear resistance of wool yarn would decrease with increasing heat treatment temperature and time, and the tensile strength retention was higher than 80% after heat treatment which could meet the requirement in daily applications. Therefore, the heat treatment is an environmentally friendly method to endow wool yarn color and it has a potential in the textile industry

Effect of Coagulating Agents on Lignin and Oligosaccharide Contents in Pre-Hydrolysis Liquor Obtained in the Production of Dissolving Pulp from Poplar Residual Slabs

Pre-hydrolysis is an important step in the poplar residual slab dissolving pulp production process, as it aids in removing as much hemicellulose as possible from the cellulose fibers. In the pre-hydrolysis process, a portion of lignin also dissolves, along with the hemicelluloses. The presence of lignin in prehydrolysis liquor (PHL) is detrimental to the separation of xylo-oligosaccharide from the prehydrolysis liquor. This study researched lignin removal from PHL with three coagulating agents, namely aluminum sulfate (alum), polyaluminum chloride (PAC), and polydiallyldimethyl ammonium chloride (pDADMAC). It was found that the removal of lignin increased as the dosage of the alum, PAC, and pDADMAC increased. Additionally, the highest retention of xylo-oligosaccharide in the PHL occurred at dosages of 120 mg/L for alum and 160 mg/L for PAC and pDADMAC. The contents of the other oligosaccharides in PHL fluctuated irregularly with increasing dosages of the alum, PAC, and pDADMAC

Reactivity Improvement of Bamboo Dissolving Pulp by Xylanase Modification

A high reactivity is an essential prerequisite for dissolving pulp. In this study, xylanase modification to increase the reactivity of bamboo dissolving pulp was investigated. The original reactivity of a bamboo dissolving pulp prepared by a prehydrolysis kraft pulping process and bleached by (OP)-H-P (oxygen delignification enhanced with peroxide - sodium hypochlorite - peroxide) is very low. The reactivity of the pulp was increased drastically after xylanase modification, which lowered the pulp’s pentosan content. Simultaneously, the crystallinity index of the dissolving pulp decreased slightly after xylanase modification. The microscopic appearance of the fiber surfaces changed slightly. The average curl and kink indices were lower at a xylanase charge of 1.0 IU/g compared to the other charges, while changes to the yield loss and the degree of polymerization were negligible. The mechanism for the increased pulp reactivity is discussed

Conversion of fructose into 5-hydroxymethylfurfural catalyzed by recyclable sulfonic acid-functionalized metal-organic frameworks

A series of sulfonic acid-functionalized metal-organic frameworks (MOF-SO3H) were prepared by postsynthetic modification (PSM) of the organic linkers within the MOF with chlorosulfonic acid. The obtained MOF-SO3H, including sulfonic acid-functionalized MIL-101(Cr) [MIL-101(Cr)-SO3H], UIO-66(Zr) [UIO-66(Zr)-SO3H], and MIL-53(Al) [MIL-53(Al)-SO3H], have been systematically studied as solid acids in fructose transformation to 5-hydroxymethylfurfural (HMF). With MIL-101(Cr)-SO3H as catalyst, a HMF yield of 90% with a full fructose conversion was obtained at 120 degrees C for 60 min in DMSO. The concentration of -SO3H in MOF-SO3H as well as the contribution of Bronsted acidity of MOF-SO3H parallels its -SO3H grafting rate. Under a lower -SO3H grafting level, a good linear correlation between catalytic activity, in terms of turnover frequency, and sulfonic acid-site density of MOF-SO3H was found. Moreover, the sulfonic acid groups, which function as the catalytic sites, are equivalent in all MOF-SO3H for fructose-to-HMF transformation, regardless of precursor MOFs. Both conversions of fructose and selectivities towards HMF increase with the sulfonic acid-site density of MOF-SO3H at an initial stage of fructose-to-HMF transformation. Kinetics studies reveal that the MIL-101(Cr)-SO3H promoted fructose-to-HMF transformation may follow pseudo-first-order kinetics with observed activation energy of 55 kJ mol(-1) under the investigated conditions. Moreover, MIL-101(Cr)-SO3H behaves as a heterogeneous catalyst and can be easily recovered and reused. The research highlights a good prospect for catalytic application of MOF-derived solid acid catalysts for biomass carbohydrate valorization