Search

目的 本研究通过探讨N6-甲基腺苷（N6-methyladenosine，m6A）修饰及其调控蛋白在脑缺血小鼠中的表达变化，为脑缺血治疗的分子靶点研究提供参考。 方法 取60只雄性C57BL/6J小鼠，随机分为假手术组、脑缺血1 d组、脑缺血3 d组和脑缺血7 d组，每组各15只，采用线栓法制作右侧大脑中动脉梗死模型，于缺血1 h进行拔栓再灌注。通过RNA提取及斑点印迹实验检测小鼠缺血侧脑组织RNA m6A水平；使用荧光定量逆转录PCR检测小鼠缺血侧脑组织甲基转移酶3（methyltransferase 3，Mettl3）、甲基转移酶14（methyltransferase 14，Mettl14）、FTO α-酮戊二酸酯依赖性双加氧酶（FTO alpha-ketoglutarate dependent dioxygenase，Fto）、RNA去甲基化酶alkB同源基因5（alkB homolog 5，RNA demethylase；Alkbh5）、YTH N6-甲基腺苷RNA结合蛋白1（YTH N6-methyladenosine RNA binding protein 1，Ythdf1）、Ythdf2和Ythdf3的mRNA表达水平；利用免疫印迹实验检测缺血侧脑组织Mettl3、Mettl14、Fto、Alkbh5、Ythdf1、Ythdf2和Ythdf3蛋白的表达水平；借助免疫荧光染色观察缺血侧脑组织梗死周边区神经元中Mettl3、Fto、Ythdf1、Ythdf2和Ythdf3蛋白的表达变化情况。 结果 与假手术组相比，脑缺血3 d组脑组织RNA的m6A水平升高（1.620±0.339 vs. 1.000±0.192，P=0.0343）。①甲基转移酶表达情况：脑缺血7 d组Mettl3 mRNA水平降低（0.675±0.059 vs. 1.000±0.131，P=0.0331）；脑缺血1 d组Mettl3（0.548±0.107 vs. 1.000±0.056，P=0.0398）、Mettl14（0.534±0.218 vs. 1.000±0.018，P=0.0108）蛋白表达水平降低；脑缺血3 d组Mettl3（0.410±0.341 vs. 1.000±0.056，P=0.0084）、Mettl14（0.429±0.283 vs. 1.000±0.018，P=0.0026）蛋白表达水平也均下降；免疫荧光染色显示脑缺血3 d组梗死周边区神经元中Mettl3蛋白表达减少。②去甲基化酶表达情况：脑缺血1 d组（0.405±0.209 vs. 1.000±0.142，P=0.0108）、脑缺血3 d组（0.530±0.125 vs. 1.000±0.142，P=0.0412）Fto蛋白表达水平降低；免疫荧光染色显示脑缺血3 d组梗死周边区神经元中Fto表达减少。③m6A结合蛋白表达情况：脑缺血1 d组Ythdf1 mRNA水平降低（0.708±0.046 vs. 1.000±0.117，P=0.0331），Ythdf3 mRNA水平升高（1.473±0.093 vs. 1.000±0.142，P=0.0012）；脑缺血3 d组Ythdf1（0.593±0.240 vs. 1.000±0.117，P=0.0034）、Ythdf2（0.664±0.177 vs. 1.000±0.200，P=0.0100）mRNA水平降低，Ythdf3 mRNA水平升高（1.451±0.281 vs. 1.000±0.142，P=0.0018）；脑缺血1 d组Ythdf1（0.486±0.177 vs. 1.000±0.091，P=0.0197）、Ythdf3（0.536±0.107 vs. 1.000±0.125，P=0.0400）蛋白表达水平降低；脑缺血3 d组Ythdf1（0.404±0.299 vs. 1.000±0.091，P=0.0079）、Ythdf2（0.279±0.189 vs. 1.000±0.261，P=0.0136）、Ythdf3（0.450±0.220 vs. 1.000±0.125，P=0.0157）蛋白表达水平均降低；免疫荧光染色显示脑缺血3 d组梗死周边区神经元中m6A结合蛋白Ythdf1、Ythdf2、Ythdf3表达均减少。 结论 小鼠脑缺血后可能由Fto表达下调导致m6A水平升高，Ythdf1、Ythdf2、Ythdf3蛋白表达水平趋势基本一致，可能存在功能冗余。 Abstract: Objective To explore the expression changes of N6-methyladenosine (m6A) and its regulatory proteins in mouse models with cerebral ischemia and to provide a reference for finding potential molecular targets for cerebral ischemia therapy. Methods A total of 60 male C57BL/6J mice were randomly divided into 4 groups: sham-operated group, 1 day post-ischemia group, 3 days post-ischemia group, and 7 days post-ischemia group, with 15 mice in each group. The model of right middle cerebral artery occlusion was established in C57BL/6J mice by thread embolization method. Reperfusion was achieved after 1 hour of ischemia. RNA extraction and dot blotting were used to detect the levels of RNA m6A in the ischemic side of the mouse brain. Fluorescence quantitative reverse transcription PCR was used to detect the mRNA expression of methyltransferase 3 (Mettl3); methyltransferase 14 (Mettl14); FTO alpha-ketoglutarate dependent dioxygenase (Fto); alkB homolog 5, RNA demethylase (Alkbh5); YTH N6-methyladenosine RNA binding protein 1 (Ythdf1); Ythdf2; and Ythdf3 in the ischemic side of the mouse brain. Western blot was used to measure the protein expression levels of Mettl3, Mettl14, Fto, Alkbh5, Ythdf1, Ythdf2, and Ythdf3 in the ischemic side of the brain. Meanwhile, immunofluorescence staining was used to observe the expression changes of Mettl3, Fto, Ythdf1, Ythdf2, and Ythdf3 in the neurons of the ischemic side of the brain. Results Compared with the sham-operated group, the m6A level of the brain tissue RNA in 3 days post-ischemia group was increased (1.620±0.339 vs. 1.000±0.192, P=0.0343). ①Expression of methyltransferase: the mRNA level of Mettl3 decreased (0.675±0.059 vs. 1.000±0.131, P=0.0331) in 7 days post-ischemia group. The protein levels of Mettl3 (0.548±0.107 vs. 1.000±0.056, P=0.0398) and Mettl14 (0.534±0.218 vs. 1.000±0.018, P=0.0108) decreased in 1 day post-ischemia group. The protein levels of Mettl3 (0.410±0.341 vs. 1.000±0.056, P=0.0084) and Mettl14 (0.429±0.283 vs. 1.000±0.018, P=0.0026) decreased in 3 days post-ischemia group. Immunofluorescence staining revealed a reduction of Mettl3 expression in the neurons around the cerebral infarction area in 3 days post-ischemia group. ②Expression of demethylase: Fto protein levels were decreased in 1 day post-ischemia group (0.405±0.209 vs. 1.000±0.142, P=0.0108) and 3 days post-ischemia group (0.530±0.125 vs. 1.000±0.142, P=0.0412). Immunofluorescence staining showed that the expression of Fto in the neurons around the cerebral infarction area decreased after 3 days of cerebral ischemia. ③Expression of m6A binding protein: Ythdf1 mRNA level decreased in 1 day post-ischemia group (0.708±0.046 vs. 1.000±0.117, P=0.0331), while Ythdf3 mRNA level was increased (1.473±0.093 vs. 1.000±0.142, P=0.0012). The mRNA levels of Ythdf1 (0.593±0.240 vs. 1.000±0.117, P=0.0034) and Ythdf2 (0.664±0.177 vs. 1.000±0.200, P=0.0100) in 3 days post-ischemia group decreased, while the mRNA level of Ythdf3 was increased (1.451±0.281 vs. 1.000±0.142, P=0.0018). The protein levels of Ythdf1 (0.486±0.177 vs. 1.000±0.091, P=0.0197) and Ythdf3 (0.536±0.107 vs. 1.000±0.125, P=0.0400) in 1 day post-ischemia group were decreased. The protein levels of Ythdf1 (0.404±0.299 vs. 1.000±0.091, P=0.0079), Ythdf2 (0.279±0.189 vs. 1.000±0.261, P=0.0136), and Ythdf3 (0.450±0.220 vs. 1.000±0.125, P=0.0157) in 3 days post-ischemia group were decreased. Immunofluorescence staining further showed a decrease in the expression of m6A binding proteins Ythdf1, Ythdf2, and Ythdf3 in the neurons around the cerebral infarction area 3 days after ischemia. Conclusions Post-ischemic downregulation of Fto in mice may lead to an elevation of m6A levels.The expression trends of Ythdf1, Ythdf2, and Ythdf3 proteins are generally consistent, indicating the existence of functional redundancy.

Abstract Accurately controlling the product selectivity in syngas conversion, especially increasing the olefin selectivity while minimizing C1 byproducts, remains a significant challenge. Epsilon Fe2C is deemed a promising candidate catalyst due to its inherently low CO2 selectivity, but its use is hindered by its poor high-temperature stability. Herein, we report the successful synthesis of highly stable ε-Fe2C through a N-induced strategy utilizing pyrolysis of Prussian blue analogs (PBAs). This catalyst, with precisely controlled Mn promoter, not only achieved an olefin selectivity of up to 70.2% but also minimized the selectivity of C1 byproducts to 19.0%, including 11.9% CO2 and 7.1% CH4. The superior performance of our ε-Fe2C-xMn catalysts, particularly in minimizing CO2 formation, is largely attributed to the interface of dispersed MnO cluster and ε-Fe2C, which crucially limits CO to CO2 conversion. Here, we enhance the carbon efficiency and economic viability of the olefin production process while maintaining high catalytic activity.

Abstract Background This study investigated whether the Combat compensation method can remove the variability of radiomic features extracted from different scanners, while also examining its impact on the subsequent predictive performance of machine learning models. Materials and methods 135 CT images of Credence Cartridge Radiomic phantoms were collected and screened from three scanners manufactured by Siemens, Philips, and GE. 100 radiomic features were extracted and 20 radiomic features were screened according to the Lasso regression method. The radiomic features extracted from the rubber and resin-filled regions in the cartridges were labeled into different categories for evaluating the performance of the machine learning model. Radiomics features were divided into three groups based on the different scanner manufacturers. The radiomic features were randomly divided into training and test sets with a ratio of 8:2. Five machine learning models (lasso, logistic regression, random forest, support vector machine, neural network) were employed to evaluate the impact of Combat on radiomic features. The variability among radiomic features were assessed using analysis of variance (ANOVA) and principal component analysis (PCA). Accuracy, precision, recall, and area under the receiver curve (AUC) were used as evaluation metrics for model classification. Results The principal component and ANOVA analysis results show that the variability of different scanner manufacturers in radiomic features was removed (P˃0.05). After harmonization with the Combat algorithm, the distributions of radiomic features were aligned in terms of location and scale. The performance of machine learning models for classification improved, with the Random Forest model showing the most significant enhancement. The AUC value increased from 0.88 to 0.92. Conclusions The Combat algorithm has reduced variability in radiomic features from different scanners. In the phantom CT dataset, it appears that the machine learning model’s classification performance may have improved after Combat harmonization. However, further investigation and validation are required to fully comprehend Combat’s impact on radiomic features in medical imaging.

External sulfate attack (ESA) coupled with wetting–drying alternation poses a significant threat to the concrete durability, while there are few models to simulate the above ESA behavior. In this paper, a simplified transport-mechanical model is proposed to numerically analyze the deterioration of concrete prism under ESA and dry-wet cycles. Firstly, a transport model of sulfate ion in concrete prism is established by considering the behaviors of ion diffusion, convection and chemical reaction, and numerically solved by the finite difference method. Secondly, the crystallization pressure of sulfate products in porous system is analyzed to calculate the equivalent expansion force. Then, the expansion strain and its-induced damage are calculated, and the criterion of boundary movement is further proposed. On the basis of model validation, a numerical simulation is performed to analyze the transport-mechanical response in concrete prism under ESA and dry-wet cycles. The results show that, there is no clear demarcation between the convection and diffusion zones in the prism. The spatial–temporal evolution of ESA-induced damage is similar to that of ion concentration. The longer the wetting time in one dry-wet cycles, the deeper the spalling of concrete prism caused by ESA.

In order to further understand the characteristics of phytoplankton community in the sea area near Changbiao Island in Xiapu, the data of phytoplankton and water environment from four cruises in May (spring), September (summer), December (autumn) and February (winter) in 2019—2020 were analyzed, and the characteristics of phytoplankton community structure were analyzed. The main environmental factors affecting the structure of phytoplankton community were studied by redundancy analysis. The results showed that there were 170 species of phytoplankton in 60 genera, 48 genera and 131 species of diatoms, 26 species of dinoflagellates in 10 genera, 2 species of cyanobacteria in 1 genera and 1 species of diatoms in 1 genera. Phytoplankton are mainly coastal wide-temperature and wide-salt species and warm water species. There are 13 dominant species throughout the year. In spring, Prorocentrum donghaiense and Noctiluca are the main species, and Skeletonema costatum and Siegesbeckia qiongshi are the main species in summer, autumn and winter. The spatial distribution of phytoplankton abundance shows a trend of high nearshore, low farshore, low in the south, and high in the north. Seasonal variation of phytoplankton is mainly affected by water temperature. Appropriate temperature and nutrients in spring and summer promote a large increase in phytoplankton, while autumn and winter are mainly affected by temperature. Now in spring and summer, the coastal nuclear power station of Changbiao Island in Xiapu should focus on monitoring the occurrence of red tide in spring and summer.

Transition metal carbide/nitride cores within MXenes make them considerably useful for ultra-high-temperature reinforcement. However, extensive research on Ti3C2Tx MXene has revealed its tendency to undergo a phase transition to TiCy at temperatures above 800 ℃ due to high activity of a superficial Ti atomic layer. Herein, spark plasma sintering of Ti3C2Tx and TiC is performed to prevent the Ti3C2Tx phase transition at temperatures up to 1900 ℃ through the fabrication of composites at a pressure of 50 MPa. Using a focused ion beam scanning electron microscope to separate layered substances in the composites and examining selected area diffraction spots in a transmission electron microscope enabled identification of non-phase-transitioned MXene. First-principles calculations based on density functional theory indicated the formation of strong chemical bonding interfaces between Ti3C2Tx and TiC, which imposed a stability constraint on the Ti atomic layer at the Ti3C2Tx surface. Mechanical performance tests, such as three-point bending and fracture toughness analysis, demonstrated that the addition of Ti3C2Tx can effectively improve the cross-scale strengthening and toughening of the TiC matrix, providing a new path for designing and developing two-dimensional (2D) carbides cross-scale-enhanced three-dimensional (3D) carbides with the same elements relying on a wide variety of MXenes.

Abstract Diabetic cystopathy (DCP) is a prevalent etiology of bladder dysfunction in individuals with longstanding diabetes, frequently leading to bladder interstitial fibrosis. Research investigating the initial pathological alterations of DCP is notably scarce. To comprehend the development of fibrosis and find effective biomarkers for its diagnosis, we prepared streptozotocin-induced long-term diabetic SD rats exhibiting a type 1 diabetes phenotype and bladder fibrosis in histology detection. After observing myofibroblast differentiation from rats’ primary bladder fibroblasts with immunofluorescence, we isolated fibroblasts derived exosomes and performed exosomal miRNA sequencing. The co-differentially expressed miRNAs (DEMis) (miR-16-5p and let-7e-5p) were screened through a joint analysis of diabetic rats and long-term patients’ plasma data (GES97123) downloaded from the GEO database. Then two co-DEMis were validated by quantitative PCR on exosomes derived from diabetic rats’ plasma. Following with a series of analysis, including target mRNAs and transcription factors (TFs) prediction, hubgenes identification, protein–protein interaction (PPI) network construction and gene enrichment analysis, a miRNA-mediated genetic regulatory network consisting of two miRNAs, nine TFs, and thirty target mRNAs were identified in relation to fibrotic processes. Thus, circulating exosomal miR-16-5p and let-7e-5p are associated with bladder fibrosis of DCP, and the crucial genes in regulatory network might hold immense significance in studying the pathogenesis and molecular mechanisms of fibrosis, which deserves further exploration.