Stent fracture after transjugular intrahepatic portosystemic shunt placement using the bare metal stent/stent-graft combination technique.

BACKGROUND: A transjugular intrahepatic portosystemic shunt (TIPS) is widely placed to treat portal hypertension. Because the Viatorr® stent (W. L. Gore and Associates, Flagstaff, AZ, United States) is not available in all hospitals in China, the bare metal stent (BMS)/stent-graft combination technique is still popular for TIPS construction. Stent fracture is a complication after TIPS placement using this technique, with limited available literature focusing on it. AIM: To assess the incidence of stent fracture after TIPS placement using the BMS/ stent-graft combination technique and to identify the risk factors for stent fracture. We proposed technique modifications to improve the clinical results of TIPS placement with the BMS/stent-graft combination technique. METHODS: We retrospectively analyzed the computed tomography (CT) data of all patients with portal hypertension who underwent the TIPS procedure between June 2011 and December 2021 in a single center. Patients implanted with the BMS/stent graft and had follow-up imaging data available were included. We identified patients with stent fracture and analyzed their characteristics. Multivariable logistic regression was applied to identify the potential predictors of stent fracture. RESULTS: Of the 68 included patients, stent fracture occurred in seven (10.3%) patients. Based on CT images, the stent fractures were categorized into three types. Our study consisted of four (57.1%) type I fractures, one (14.3%) type II fracture, one (14.3%) type IIIa fracture, and one (14.3%) type IIIb fracture. After adjusting for covariates, multivariable logistic regression revealed that the risk factors for stent fracture were the implantation of a greater number of stents [adjusted odds ratio (aOR) = 22.2, 95% confidence interval (CI): 1.2-415.4, P = 0.038] and a larger proximal sagittal stent bending angle (aOR = 1.1, 95%CI: 1.0-1.3, P = 0.020). CONCLUSION: Stent fracture occurred in approximately 10% of patients with portal hypertension who underwent TIPS with the BMS/stent-graft combination technique. The number of implanted stents and stent bending angle at the inferior vena cava end were predictors of stent fracture, which suggests that the incidence of stent fracture could potentially be reduced by procedural modifications.

[Research progress of relationship between continuous cropping obstacles and microRNAs in Rehmannia glutinosa].

The efficacy of Rehmannia glutinosa which as a large quantity of traditional Chinese medicine is significant. However, the land must be given up after one season of R. glutinosa cultivation or replanted after a period of 8-10 years because of the severe continuous cropping obstacles. MicroRNAs is a class of endogenous non-coding small RNAs, which participate in regulation of physiological activities by target mRNA cleavage or translational repression in plants. In recent years,studies on the role of miRNAs in plants have made significant progresses,especially in medicinal plants．MiRNAs from some different medicinal plant species have been identified with regulatory effects．When plants are exposed to environmental stress, miRNAs act on stress-related genes and initiate stress-resistance mechanisms in the body against adverse factors. R. glutinosa is also a kind of environmental stress. It is conducive to deciphering the molecular mechanism of continuous cropping obstacles for us by researching miRNAs. This article reviews the production of miRNAs, mechanism, research approaches and characteristics of resisting the environmental stresses in plants, the development trends and future prospect of R. glutinosa miRNAs research.

PARAQUAT TOLERANCE3 Is an E3 Ligase That Switches off Activated Oxidative Response by Targeting Histone-Modifying PROTEIN METHYLTRANSFERASE4b.

Oxidative stress is unavoidable for aerobic organisms. When abiotic and biotic stresses are encountered, oxidative damage could occur in cells. To avoid this damage, defense mechanisms must be timely and efficiently modulated. While the response to oxidative stress has been extensively studied in plants, little is known about how the activated response is switched off when oxidative stress is diminished. By studying Arabidopsis mutant paraquat tolerance3, we identified the genetic locus PARAQUAT TOLERANCE3 (PQT3) as a major negative regulator of oxidative stress tolerance. PQT3, encoding an E3 ubiquitin ligase, is rapidly down-regulated by oxidative stress. PQT3 has E3 ubiquitin ligase activity in ubiquitination assay. Subsequently, we identified PRMT4b as a PQT3-interacting protein. By histone methylation, PRMT4b upregulates the expression of APX1 and GPX1, encoding two key enzymes against oxidative stress. On the other hand, PRMT4b is recognized by PQT3 for targeted degradation via 26S proteasome. Therefore, we have identified PQT3 as an E3 ligase that acts as a negative regulator of activated response to oxidative stress and found that histone modification by PRMT4b at APX1 and GPX1 loci plays an important role in oxidative stress tolerance.

[Fluorescence Properties of Glomalin and Its Relationship with Soil Physyicochemical Characteristics in Different Regions of Beijing City].

Glomalin-related soil proteins (GRSP), which has been used as a presumable biological indicator of soil quality, is of vital ecological importance. In this research, we tested the GRSP content and physicochemical property of soils collected in mountain, urban and suburb areas of Beijing City. Besides, the fluorescence property of GRSP was also studied by using EEM-PARAFAC. The results showed that GRSP could be decomposed into five compounds, terrestrial humic-like substances UVA, terrestrial humic-like substances UVC, oxidized quinones, soil fulvic acid and amino acids. The GRSP content and protein-like fluorescence substances in urban and suburb areas significant decreased and oxidized quinones content elevated in comparison with those in mountain area. The physicochemical property was also shaped by urbanization. Compare to mountain area, moisture content, total organic matters and total nitrogen significantly decreased in urban area soil and suburb area. GRSP content, terrestrial humic-like substances UVA and oxidized quinones content showed significant correlation with soil organic matter and total nitrogen. Base on that, an integrated index system mainly consisting of GRSP concentration and C1 component and C3 component was recommended to evaluate the soil health status.

BiOBr hierarchical microspheres: Microwave-assisted solvothermal synthesis, strong adsorption and excellent photocatalytic properties.

Two kinds of BiOBr nanosheets-assembled microspheres were successfully prepared via a facile, rapid and reliable microwave-assisted solvothermal route, employing Bi(NO(3))(3)·5H(2)O and cetyltrimethylammonium bromide (CTAB) as starting reagents in the absence or presence of oleic acid. The phase and morphology of the products were characterized by powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). Experiments indicated that the formation of these building blocks of microspheres could be ascribed to the self-assembly of nanoparticles according to mesocrystal growth mode. Interestingly, both samples exhibited not only strong adsorption abilities, but also excellent photocatalytic activities for methyl orange (MO), rhodamine B (RhB) and phenol. The resulting BiOBr hierarchical microspheres are very promising adsorbents and photocatalysts for the treatment of organic pollutants.

Decoding the epigenetic language of plant development.

Epigenetics refers to the study of heritable changes in gene expression or cellular phenotype without changes in DNA sequence. Epigenetic regulation of gene expression is accomplished by DNA methylation, histone modifications, histone variants, chromatin remodeling, and may involve small RNAs. DNA methylation at cytosine is carried out by enzymes called DNA Methyltransferases and is involved in many cellular processes, such as silencing of transposable elements and pericentromeric repeats, X-chromosome inactivation and genomic imprinting, etc. Histone modifications refer to posttranslational covalent attachment of chemical groups onto histones such as phosphorylation, acetylation, and methylation, etc. Histone variants, the non-canonical histones with amino acid sequences divergent from canonical histones, can have different epigenetic impacts on the genome from canonical histones. Higher-order chromatin structures maintained or modified by chromatin remodeling proteins also play important roles in regulating gene expression. Small non-coding RNAs play various roles in the regulation of gene expression at pre- as well as posttranscriptional levels. A special issue of Molecular Plant on 'Epigenetics and Plant Development' (Volume 4, Number 2, 2009) published a variety of articles covering many aspects of epigenetic regulation of plant development. We have tried here to present a bird's-eye view of these credible efforts towards understanding the mysterious world of epigenetics. The majority of the articles are about the chromatin modifying proteins, including histone modifiers, histone variants, and chromatin remodeling proteins that regulate various developmental processes, such as flowering time, vernalization, stem cell maintenance, and response to hormonal and environmental stresses, etc. Regulation of expression of seed transcriptome, involvement of direct tandem repeat elements in the PHE1 imprinting in addition to PcG proteins activity, paramutation, and epigenetic barriers in species hybridization are described well. The last two papers are about the Pol V-mediated heterochromatin formation independent of the 24nt-siRNA and the effect of genome position and tissue type on epigenetic regulation of gene expression. These findings not only further our current understanding of epigenetic mechanisms involved in many biological phenomena, but also pave the path for the future work, by raising many new questions that are discussed in the following lines.