Structural basis of tolvaptan binding to the vasopressin V2 receptor.

The vasopressin V2 receptor (V2R) is a validated therapeutic target for autosomal dominant polycystic kidney disease (ADPKD), with tolvaptan being the first FDA-approved antagonist. Herein, we used Gaussian accelerated molecular dynamics simulations to investigate the spontaneous binding of tolvaptan to both active and inactive V2R conformations at the atomic-level. Overall, the binding process consists of two stages. Tolvaptan binds initially to extracellular loops 2 and 3 (ECL2/3) before overcoming an energy barrier to enter the pocket. Our simulations result highlighted key residues (e.g., R181, Y205, F287, F178) involved in this process, which were experimentally confirmed by site-directed mutagenesis. This work provides structural insights into tolvaptan-V2R interactions, potentially aiding the design of novel antagonists for V2R and other G protein-coupled receptors.

Exosomes combined with biosynthesized cellulose conduits improve peripheral nerve regeneration.

Peripheral nerve injury is one of the more common forms of peripheral nerve disorders, and the most severe type of peripheral nerve injury is a defect with a gap. Biosynthetic cellulose membrane (BCM) is a commonly used material for repair and ligation of nerve defects with gaps. Meanwhile, exosomes from mesenchymal stem cells can promote cell growth and proliferation. We envision combining exosomes with BCMs to leverage the advantages of both to promote repair of peripheral nerve injury. Prepared exosomes were added to BCMs to form exosome-loaded BCMs (EXO-BCM) that were used for nerve repair in a rat model of sciatic nerve defects with gaps. We evaluated the repair activity using a pawprint experiment, measurement and statistical analyses of sciatica function index and thermal latency of paw withdrawal, and quantitation of the number and diameter of regenerated nerve fibers. Results indicated that EXO-BCM produced comprehensive and durable repair of peripheral nerve defects that were similar to those for autologous nerve transplantation, the gold standard for nerve defect repair. EXO-BCM is not predicted to cause donor site morbidity to the patient, in contrast to autologous nerve transplantation. Together these results indicate that an approach using EXO-BCM represents a promising alternative to autologous nerve transplantation, and could have broad applications for repair of nerve defects.

Defluorinative Alkylation of Trifluoromethylbenzimidazoles Enabled by Spin-Center Shift: A Synergistic Photocatalysis/Thiol Catalysis Process with CO2•.

We describe a catalytic strategy for direct single C(sp3)-F bond alkylation of trifluoromethylbenzimidazoles under a photoinduced thiol catalysis process. The CO2 radical anion (CO2•-) proved to be the most efficient single-electron reductant to realize such a transformation. The spin-center shift of the generated radical anion intermediate is the key step in realizing C-F bond activation under mild conditions with high efficiency.

Risk Factors for Recurrence of Chronic Subdural Hematoma: A Single Center Experience.

OBJECTIVE: Chronic subdural hematoma (CSDH) is a common form of intracranial hemorrhage with a substantial recurrence rate. We aimed to investigate the predictive factors for the postsurgical recurrence of CSDH. METHODS: We retrospectively reviewed the medical records of patients with CSDH who underwent surgery in West China Hospital between January 2012 and June 2018. Univariate and multivariate analyses were performed to identify the relationships between recurrence of CSDH and factors such as age, sex, history of injury, Markwalder grading, computed tomography findings, surgical methods, and outcomes. RESULTS: A total of 328 patients (281 men and 47 women) aged 22-93 years (mean age, 65.14 ± 13.76 years) were included. Computed tomography findings at admission showed mixed density hematoma in 136 patients, isodensity hematoma in 140, high-density hematoma in 34, and low-density hematoma in 18. The mortality and recurrence rate were 0.30% (1 of 328) and 2.44% (8 of 328), respectively. Six months postoperatively, 327 patients had Markwalder grade 0. Hematoma recurred in 8 patients of which 7 were mixed density hematoma and 1 was isodensity hematoma. Six patients who underwent craniotomy had thickened inner neomembrane that was resected. Univariate and multivariate analyses found mixed density hematoma to be an independent risk factor for the recurrence of CSDH. CONCLUSIONS: Burr hole craniostomy with irrigation and closed-system drainage is effective for the surgical treatment of CSDH. Mixed density hematoma is an independent predictor for the recurrence of CSDH. Presence of thick inner neomembrane might be the primary cause of CSDH recurrence.

Risk assessment and genomic characterization of Zika virus in China and its surrounding areas.

BACKGROUND: Zika virus (ZIKV) has emerged as a global pathogen causing significant public health concerns. China has reported several imported cases where ZIKV were carried by travelers who frequently travel between China and ZIKV-endemic regions. To fully characterize the ZIKV strains isolated from the cases reported in China and assess the risk of ZIKV transmission in China, comprehensive phylogenetic and genetic analyses were performed both on all ZIKV sequences of China and on a group of scientifically selected ZIKV sequences reported in some of the top interested destinations for Chinese travelers. METHODS: ZIKV genomic sequences were retrieved from the National Center for Biotechnology Information database through stratified sampling. Recombination event detection, maximum likelihood (ML) phylogenetic analysis, molecular clock analysis, selection pressure analysis, and amino acid substitution analysis were used to reconstruct the epidemiology and molecular transmission of ZIKV. RESULTS: The present study investigated 18 ZIKV sequences from China and 70 sequences from 16 selected countries. Recombination events rarely happens in all ZIKV Asian lineage. ZIKV genomes were generally undergone episodic positive selection (17 sites), and only one site was under pervasive positive selection. All ZIKV imported into China were Asian lineage and were assigned into two clusters: Venezuela-origin (cluster A) and Samoa-origin cluster (cluster B) with common ancestor from French Polynesia. The time of most recent common ancestors of Cluster A dated to approximately 2013/11 (95% highest posterior density [HPD] 2013/06, 2014/03) and cluster B dated to 2014/08 (95% HPD 2014/02, 2015/01). Cluster B is more variable than Cluster A in comparison with other clusters, but no varied site of biological significance was revealed. ZIKV strains in Southeast Asia countries are independent from strains in America epidemics. CONCLUSIONS: The genetic evolution of ZIKV is conservative. There are two independent introductions of ZIKV into China and China is in danger of autochthonous transmission of ZIKV because of high-risk surrounding areas. Southeast Asia areas have high risk of originating the next large-scale epidemic ZIKV strains.

Viability, biofilm formation, and MazEF expression in drug-sensitive and drug-resistant Mycobacterium tuberculosis strains circulating in Xinjiang, China.

BACKGROUND: Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB) is one of the most common chronic infectious amphixenotic diseases worldwide. Prevention and control of TB are greatly difficult, due to the increase in drug-resistant TB, particularly multidrug-resistant TB. We speculated that there were some differences between drug-sensitive and drug-resistant MTB strains and that mazEF3,6,9 toxin-antitoxin systems (TASs) were involved in MTB viability. This study aimed to investigate differences in viability, biofilm formation, and MazEF expression between drug-sensitive and drug-resistant MTB strains circulating in Xinjiang, China, and whether mazEF3,6,9 TASs contribute to MTB viability under stress conditions. MATERIALS AND METHODS: Growth profiles and biofilm-formation abilities of drug-sensitive, drug-resistant MTB strains and the control strain H37Rv were monitored. Using molecular biology experiments, the mRNA expression of the mazF3, 6, and 9 toxin genes, the mazE3, 6, and 9 antitoxin genes, and expression of the MazF9 protein were detected in the different MTB strains, H37RvΔmazEF3,6,9 mutants from the H37Rv parent strain were generated, and mutant viability was tested. RESULTS: Ex vivo culture analyses demonstrated that drug-resistant MTB strains exhibit higher survival rates than drug-sensitive strains and the control strain H37Rv. However, there was no statistical difference in biofilm-formation ability in the drug-sensitive, drug-resistant, and H37Rv strains. mazE3,6 mRNA-expression levels were relatively reduced in the drug-sensitive and drug-resistant strains compared to H37Rv. Conversely, mazE3,9 expression was increased in drug-sensitive strains compared to drug-resistant strains. Furthermore, compared with the H37Rv strain, mazF3,6 expression was increased in drug-resistant strains, mazF9 expression was increased in drug-sensitive strains, and mazF9 exhibited reduced expression in drug-resistant strains compared with drug-sensitive strains. Protein expression of mazF9 was increased in drug-sensitive and drug-resistant strains compared to H37Rv, while drug-resistant strains exhibited reduced mazF9 expression compared to drug-sensitive strains. Compared to H37Rv, H37RvΔmazEF3,6,9-deletion mutants grew more slowly under both stress conditions, and their ability to survive in host macrophages was also weaker. Furthermore, the host macrophage-apoptosis rate was higher after infection with any of the H37RvΔmazEF3,6,9 mutants than with the H37Rv strain. CONCLUSION: The increased viability of MTB drug-resistant strains compared with drug-sensitive strains is likely to be related to differential MazEF mRNA and protein expression. mazEF3,6,9 TASs contribute to MTB viability under stress conditions.

[Effects of hypoxia preconditioning on serum NGB and S-100B in patients with intracranial aneurysm surgery].

OBJECTIVE: To study the clinical effects of hypoxia preconditioning (HPC) and its effects on serum neuroglobin (NGB) and S-100B level in the patients undergoing intracranial aneurysm surgery. METHODS: Forty patients scheduled to intracranial aneurysm surgery were randomly.divided into 2 groups: HPC group (n= 20) and control group (n= 20). The patients in HPC group were treated with 3 cycles of deoxidation-reoxygenation after intubation. The time of deoxidation in each HPC cycle was recorded, while vital signs were also recorded in each corresponding time point. Blood samples were obtained from exsanguinate radial artery and jugular bulb section at the end of each HPC cycle and corresponding time points during operation to measure serum level of NGB and S100B protein and to analysis blood gas. RESULTS: During HPC process, the patients in group HPC experienced mild hypoxia and CO2 retention. With the times of HPC increasing, CO2 retention degree became heavier (P<0. 05) while hypoxia improved, the patients need more time to make SpO2 from 100% to 90% (P<0. 05). From T2 to T4 (the end of the third reoxygenation, during skull opened and aneurysm dipped, skull closed), NGB in group HPC was higher than that in control (P<0. 05), but S-100B level was not different between HPC and control group (P>0. 05). CONCLUSION: HPC could induce compensatory ability of the body to hypoxia, which might be related to the up-regulation of NGB expression.

Association of polymorphisms in the DCDC2 gene with developmental dyslexia in the Han Chinese.

BACKGROUND: Genetic association studies on populations of European origin have identified the DCDC2 gene as a susceptibility locus for developmental dyslexia. Here, we sought to investigate the association of DCDC2 polymorphisms with developmental dyslexia in children of Han Chinese origin. METHODS: We undertook a case-control genetic association study on 76 dyslexic children and 79 non-dyslexic matched controls. We isolated DNA from oral mucosal cell samples and genotyped two DCDC2 coding-sequence single nucleotide polymorphisms, rs2274305 and rs6456593, in each sample using SNaPshot single nucleotide extension. We compared the allele and genotype frequencies between the groups using the χ(2) test and analyzed the relationship between dyslexia and the polymorphism at both loci using unconditional logistic regression. We also predicted haplotypes and compared their frequencies between the two groups. RESULTS: The differences in the genotype distribution and the allelic genes of the two single nucleotide luci of the DCDC2 gene, rs2274305 and rs6456593, between the two dyslexic and non-dyslexic groups were statistically meaningless (P > 0.05). The differences in the haplotype distributions of the DCDC2 gene between the dyslexic and normal group were statistically meaningless (P > 0.05). CONCLUSION: The DCDC2 gene may not be a susceptibility factor for developmental dyslexia among the Han Chinese. However, methodological issues may have prevented the detection of positive associations.

Antitumor constituents from the leaves of Carya cathayensis.

This study aimed to find cytotoxic chemical constituents from Carya cathayensis leaves (LCC) by using various chromatographic procedures. Identification of the chemical constituents was carried out by various spectroscopic techniques and classical chemical methods. The cytotoxic activity of the constituents was assayed on HeLa and HepG2 cell lines by staining with 3-(4,5-dimethylthiahiazol-2-y1)-2,5-di-phenytetrazolium bromide (MTT). Six flavanoids, namely (1) pinostrobin, (2) pinostrobin chalcone, (3) wogonin, (4) cardamonin, (5) alpinetin and (6) tectochrysin were identified from this species. Compounds 2-6 were isolated from this kind of plant for the first time. MTT results showed that wogonin has a moderate cytotoxic activity with IC(50) values of 17.03 ± 2.41 and 44.23 ± 3.87 µM against HeLa and HepG2 cell lines, respectively. According to the correlation of primary the structure and activity, 8-methoxy substituent in these flavones may be a major factor of the antitumor activity.

Design and diversity-oriented synthesis of novel 1,4-thiazepan-3-ones fused with bioactive heterocyclic skeletons and evaluation of their antioxidant and cytotoxic activities.

This study has achieved the design and diversity-oriented synthesis of novel 1,4-thiazepine derivatives embedded with carbazole, pyrazole or isoxazole motif via microwave-assisted multicomponent reactions under solvent-free condition, thus providing a green and facile access to 1,4-thiazepine derivatives with prominent features of high structural diversity, short reaction time, high yields and environmental friendliness. More importantly, these novel compounds have been subjected to the test of in vitro antioxidant and cytotoxic activities, resulting in the finding that these 1,4-thiazepine derivatives not only have significant antioxidant activity, but also exhibit remarkably selective cytotoxicity to carcinoma cell line HCT 116.

A novel biosynthetic hybrid scaffold seeded with olfactory ensheathing cells for treatment of spinal cord injuries.

BACKGROUND: Implantation of tissue-engineered scaffolds is one of the most promising therapeutic strategies for inducing nerve regenerations following spinal cord injuries. In this paper, we report a novel bioengineered hybrid scaffold comprised of three major extracellular matrix (ECM) proteins. METHODS: ECM-scaffolds (ECM-S) were prepared by gelling fibrinogen, fibronectin and laminin using fresh rat plasma. Olfactory ensheathing cells (OECs) were isolated from fresh rat olfactory mucosa, purified under differential adhesion, and assessed by immunofluorescent staining. OECs were seeded onto ECM-S and cultured. The effects of the scaffolds on the seeded cells were detected using the immunofluorescent staining, Western blotting, scanning electron microscopy and transmission electron microscopy. RESULTS: Tissue-engineered ECM-S could be easily molded into mat-like or cylindrical shapes and gelled by addition of fresh plasma. Observations by electron microscopy show that the ECM-S forms a stable three-dimensional porous network. Studies on the effects of the ECM-S on the biological behaviors of OECs in vitro indicate that the scaffold can promote OEC adhesion, proliferation and process extensions. Additionally, OECs seeded on the scaffold maintained the expression of nerve growth factor, matrix metalloproteinase-3 and matrix metalloproteinase-9. CONCLUSION: We developed a biosynthetic hybrid gel which could be used as a scaffold for OEC transplantation; this gel can promote nerve regeneration following spinal cord injuries.

Synthesis of isoxazolo[5,4-b]pyridines by microwave-assisted multi-component reactions in water.

A series of new polycyclic-fused isoxazolo[5,4-b]pyridines were obtained by a one-pot tandem reaction under microwave irradiation in water. Without any use of additional reagent or catalyst, the synthetic protocol represents a green one and makes this methodology suitable for library synthesis in drug discovery efforts.

A new mild base-catalyzed Mannich reaction of hetero-arylamines in water: highly efficient stereoselective synthesis of beta-aminoketones under microwave heating.

A new mild base-catalyzed Mannich reaction of aromatic aldehydes with 1,2-diphenylethanone and hetero-arylamines including pyridin-2-amine and pyrimidin-2-amine is described. In this reaction, a series of new beta-aminoketones were stereoselectively synthesized in water by controlling the steric hindrance of the substrates under microwave heating. This method has the advantages of a short synthetic route, operational simplicity, increased safety for small-scale high-speed synthesis, and minimal environmental impact.

An efficient and chemoselective synthesis of benzo[e][1,4]thiazepin-2(1H,3H,5H)-ones via a microwave-assisted multi-component reaction in water.

A new and efficient strategy for the synthesis of benzo[e][1,4]thiazepin-2(1H,3H,5H)-ones via a microwave-assisted multi-component reaction in aqueous media is described.

Microwave-assisted combinatorial synthesis of new 3-pyrimidin-5-ylpropanamides via a solvent-dependent chemoselective reaction.

A series of new 3-pyrimidin-5-ylpropanamides was selectively synthesized via a microwave-assisted, chemoselective reaction of arylidene-Meldrum's acid, 6-hydroxypyrimidin-4(3H)-one, and structurally diverse amines including (S or R)-1-phenylethanamine, cyclohexanamine, and cyclopentanamine depended on nature of solvents. In this reaction, the utilization of HOAc as a solvent leads to 3-pyrimidin-5-ylpropanamides, whereas water as reaction media results in the spiro[5.5]undecane-1,5,9-triones from same starting materials. This method has the advantages of short synthetic route, operational simplicity, increased safety for small-scale high-speed synthesis, and minimal environment impact.

In situ expression and significance of B7 costimulatory molecules within tissues of human gastric carcinoma.

AIM: To explore the role and significance of costimulatory molecules B7H1,B7H2 and ICOS within tissues of human gastric carcinoma and the possible mechanisms in tumor escape. METHODS: mRNA expressions of costimulatory molecules including B7H1,B7H2,ICOS and B7-1 in tissues of human gastric carcinoma were investigated by in situ hybridization using digoxigenin-labeled oligonucleotide-probes. The tissue of chronic gastric ulcer was used as a control. All data were analyzed by SPSS statistic software. RESULTS: At the site of gastric carcinoma, mRNA expression levels of B7H1, B7H2 and ICOS were much higher than that of B7-1. Their mRNA positive expression indexes were 0.512+/-0.333, 0.812+/-0.454, 0.702+/-0.359 and 0.293+/-0.253, respectively. The positively stained cells were mainly tumor infiltrating lymphocytes (TILs), and some tumor cells. The difference between them was greatly significant P<0.005. The mRNA expression levels of four molecules were not correlated to the pathological grade and matastasis of gastric carcinoma. CONCLUSION: ICOS-B7H costimulatory pathway may be predominant at the site of gastric carcinoma. B7-1mRNA might be the basis of ICOS-B7H interaction. ICOS-B7H interaction induces the production of IL-10 which inhibits the antitumor immune responses. Therefore, it is supposed that ICOS-B7H costimulatory pathway may be involved in the negative regulation of cell-mediated immune responses.