4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene,a Major Active Metabolite of Bisphenol A,Triggers Pancreatic β-Cell Death via a JNK/AMPKα Activation-Regulated Endoplasmic Reticulum Stress-Mediated Apoptotic Pathway

4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a major active metabolite of bisphenol A (BPA), is generated in the mammalian liver. Some studies have suggested that MBP exerts greater toxicity than BPA. However, the mechanism underlying MBP-induced pancreatic β-cell cytotoxicity remains largely unclear. This study demonstrated the cytotoxicity of MBP in pancreatic β-cells and elucidated the cellular mechanism involved in MBP-induced β-cell death. Our results showed that MBP exposure significantly reduced cell viability, caused insulin secretion dysfunction, and induced apoptotic events including increased caspase-3 activity and the expression of active forms of caspase-3/-7/-9 and PARP protein. In addition, MBP triggered endoplasmic reticulum (ER) stress, as indicated by the upregulation of GRP 78, CHOP, and cleaved caspase-12 proteins. Pretreatment with 4-phenylbutyric acid (4-PBA; a pharmacological inhibitor of ER stress) markedly reversed MBP-induced ER stress and apoptosis-related signals. Furthermore, exposure to MBP significantly induced the protein phosphorylation of JNK and AMP-activated protein kinase (AMPK)α. Pretreatment of β-cells with pharmacological inhibitors for JNK (SP600125) and AMPK (compound C), respectively, effectively abrogated the MBP-induced apoptosis-related signals. Both JNK and AMPK inhibitors also suppressed the MBP-induced activation of JNK and AMPKα and of each other. In conclusion, these findings suggest that MBP exposure exerts cytotoxicity on β-cells via the interdependent activation of JNK and AMPKα, which regulates the downstream apoptotic signaling pathway.     

Mangiferin Inhibits Apoptosis in Doxorubicin-Induced Vascular Endothelial Cells via the Nrf2 Signaling Pathway

Doxorubicin increases endothelial permeability, hence increasing cardiomyocytes’ exposure to doxorubicin (DOX) and exposing myocytes to more immediate damage. Reactive oxygen species are major effector molecules of doxorubicin’s activity. Mangiferin (MGN) is a xanthone derivative that consists of C-glucosylxanthone with additional antioxidant properties. This particular study assessed the effects of MGN on DOX-induced cytotoxicity in human umbilical vein endothelial cells’ (HUVECs’) signaling networks. Mechanistically, MGN dramatically elevated Nrf2 expression at both the messenger RNA and protein levels through the upregulation of the PI3K/AKT pathway, leading to an increase in Nrf2-downstream genes. Cell apoptosis was assessed with a caspase-3 activity assay, transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) staining was performed to assess DNA fragmentation, and protein expression was determined by Western blot analysis. DOX markedly increased the generation of reactive oxygen species, PARP, caspase-3, and TUNEL-positive cell numbers, but reduced the expression of Bcl-2 and antioxidants’ intracellular concentrations. These were effectively antagonized with MGN (20 μM), which led to HUVECs being protected against DOX-induced apoptosis, partly through the PI3K/AKT-mediated NRF2/HO-1 signaling pathway, which could theoretically protect the vessels from severe DOX toxicity.     

Crosstalk between MicroRNA and Oxidative Stress in Primary Open-Angle Glaucoma

Reactive oxygen species (ROS) plays a key role in the pathogenesis of primary open-angle glaucoma (POAG), a chronic neurodegenerative disease that damages the trabecular meshwork (TM) cells, inducing apoptosis of the retinal ganglion cells (RGC), deteriorating the optic nerve head, and leading to blindness. Aqueous humor (AH) outflow resistance and intraocular pressure (IOP) elevation contribute to disease progression. Nevertheless, despite the existence of pharmacological and surgical treatments, there is room for the development of additional treatment approaches. The following review is aimed at investigating the role of different microRNAs (miRNAs) in the expression of genes and proteins involved in the regulation of inflammatory and degenerative processes, focusing on the delicate balance of synthesis and deposition of extracellular matrix (ECM) regulated by chronic oxidative stress in POAG related tissues. The neutralizing activity of a couple of miRNAs was described, suggesting effective downregulation of pro-inflammatory and pro-fibrotic signaling pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), transforming growth factor-beta 2 (TGF-β2), Wnt/β-Catenin, and PI3K/AKT. In addition, with regards to the elevated IOP in many POAG patients due to increased outflow resistance, Collagen type I degradation was stimulated by some miRNAs and prevented ECM deposition in TM cells. Mitochondrial dysfunction as a consequence of oxidative stress was suppressed following exposure to different miRNAs. In contrast, increased oxidative damage by inhibiting the mTOR signaling pathway was described as part of the action of selected miRNAs. Summarizing, specific miRNAs may be promising therapeutic targets for lowering or preventing oxidative stress injury in POAG patients.     

Mitochondrial and Autophagic Regulation of Adult Neurogenesis in the Healthy and Diseased Brain

Adult neurogenesis is a highly regulated process during which new neurons are generated from neural stem cells in two discrete regions of the adult brain: the subventricular zone of the lateral ventricle and the subgranular zone of the dentate gyrus in the hippocampus. Defects of adult hippocampal neurogenesis have been linked to cognitive decline and dysfunction during natural aging and in neurodegenerative diseases, as well as psychological stress-induced mood disorders. Understanding the mechanisms and pathways that regulate adult neurogenesis is crucial to improving preventative measures and therapies for these conditions. Accumulating evidence shows that mitochondria directly regulate various steps and phases of adult neurogenesis. This review summarizes recent findings on how mitochondrial metabolism, dynamics, and reactive oxygen species control several aspects of adult neural stem cell function and their differentiation to newborn neurons. It also discusses the importance of autophagy for adult neurogenesis, and how mitochondrial and autophagic dysfunction may contribute to cognitive defects and stress-induced mood disorders by compromising adult neurogenesis. Finally, I suggest possible ways to target mitochondrial function as a strategy for stem cell-based interventions and treatments for cognitive and mood disorders.     

Research advances in residual thermal stress of ceramic/metal brazes

Brazing, as a common method of bonding ceramic and metal, has been applied in microelectronics, aerospace, machinery and other domains extensively. The residual thermal stress in the brazed joint has direct effects on the mechanical properties of the joint, so how to control the generation of residual thermal stress has become the vital point. In this paper, the methods of reducing residual thermal stress in the brazing process in recent years are reviewed. The generation and effects of residual thermal stress in the brazed joint are introduced. Besides, the methods of detecting residual thermal stress are discussed, and different methods of reducing residual thermal stress in brazed joints are also analyzed. Finally, the future development directions of reducing residual thermal stress in the brazed joint are proposed.     

Amyloid-Beta Induces Different Expression Pattern of Tissue Transglutaminase and Its Isoforms on Olfactory Ensheathing Cells: Modulatory Effect of Indicaxanthin

Herein, we assessed the effect of full native peptide of amyloid-beta (Aβ) (1-42) and its fragments (25-35 and 35-25) on tissue transglutaminase (TG2) and its isoforms (TG2-Long and TG2-Short) expression levels on olfactory ensheathing cells (OECs). Vimentin and glial fibrillary acid protein (GFAP) were also studied. The effect of the pre-treatment with indicaxanthin from Opuntia ficus-indica fruit on TG2 expression levels and its isoforms, cell viability, total reactive oxygen species (ROS), superoxide anion (O₂⁻), and apoptotic pathway activation was assessed. The levels of Nestin and cyclin D1 were also evaluated. Our findings highlight that OECs exposure to Aβ(1-42) and its fragments induced an increase in TG2 expression levels and a different expression pattern of its isoforms. Indicaxanthin pre-treatment reduced TG2 overexpression, modulating the expression of TG2 isoforms. It reduced total ROS and O₂⁻ production, GFAP and Vimentin levels, inhibiting apoptotic pathway activation. It also induced an increase in the Nestin and cyclin D1 expression levels. Our data demonstrated that indicaxanthin pre-treatment stimulated OECs self-renewal through the reparative activity played by TG2. They also suggest that Aβ might modify TG2 conformation in OECs and that indicaxanthin pre-treatment might modulate TG2 conformation, stimulating neural regeneration in Alzheimer’s disease.     

Stem Photosynthesis—A Key Element of Grass Pea (Lathyrus sativus L.) Acclimatisation to Salinity

Grass pea (Lathyrus sativus) is a leguminous plant of outstanding tolerance to abiotic stress. The aim of the presented study was to describe the mechanism of grass pea (Lathyrus sativus L.) photosynthetic apparatus acclimatisation strategies to salinity stress. The seedlings were cultivated in a hydroponic system in media containing various concentrations of NaCl (0, 50, and 100 mM), imitating none, moderate, and severe salinity, respectively, for three weeks. In order to characterise the function and structure of the photosynthetic apparatus, Chl a fluorescence, gas exchange measurements, proteome analysis, and Fourier-transform infrared spectroscopy (FT-IR) analysis were done inter alia. Significant differences in the response of the leaf and stem photosynthetic apparatus to severe salt stress were observed. Leaves became the place of harmful ion (Na⁺) accumulation, and the efficiency of their carboxylation decreased sharply. In turn, in stems, the reconstruction of the photosynthetic apparatus (antenna and photosystem complexes) activated alternative electron transport pathways, leading to effective ATP synthesis, which is required for the efficient translocation of Na⁺ to leaves. These changes enabled efficient stem carboxylation and made them the main source of assimilates. The observed changes indicate the high plasticity of grass pea photosynthetic apparatus, providing an effective mechanism of tolerance to salinity stress.     

渗流作用下新型装配重力式挡土墙有限元分析

为研究渗流作用下新型装配重力式挡土墙应力变化及墙体排水通道对墙后土体固结的影响,采用ABAQUS进行有限元分析,有限元分析结果与模型试验结果相吻合,证明该模型的合理性。在此基础上研究渗流作用下墙体应力变化趋势及墙体排水通道对墙后土体固结效果的影响。研究结果表明:横向排水通道对墙后土体固结效果的影响优于纵向排水通道对土体固结效果的影响,墙体底部横向排水通道的影响作用最显著;渗流作用下墙体应力由上往下呈先增大后减小的趋势,墙体下部所受最大水平剪应力最大。     

Effects of TGO growth on the stress distribution and evolution of three-dimensional cylindrical thermal barrier coatings based on finite element simulations

Based on the ultrasonic C-scan results of 8YSZ coatings after thermal cycles, three-dimensional cylindrical numerical simulations of the physical geometry model of the thermal barrier coating (TBC) sinusoidal surfaces were conducted with finite elements to estimate the stress distribution and evolution law of the top coat (TC)/bond coat (BC) interface, including the centre and edge of the specimen affected by the dynamic growth of the thermally grown oxide (TGO). The results show that when a layer of TGO is grown on the TC/BC interface, compressive stress is uniformly distributed on the TGO interface, and the stress value decreases as a function of the TGO layer thickness. When the thickness of the TGO exceeds a certain value, the compressive stress of all parts of the interface gradually changes to tensile stress; meanwhile, the edges of the model affected by the crest and trough effects of the wave are reflected in the radial and circumferential directions, especially along the axial direction, with alternating concentrated tensile and compressive stresses. TGO growth imposes a minor influence on the magnitude and distributions of the radial and circumferential stresses at the BC interface. The linear elasticity, creep, fatigue, and stress accumulation effects of each layer of TBCs in each thermal cycle were fully considered in this model. The model not only interprets the crest and trough effects of the TC/BC surface interface during the growth of TGO, but also interprets the effects of the core and edge of the cylindrical model, further revealing the reason for which the core and edge of the TBC will most likely form cracks.