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251. Path analysis of the promotion of design to creative industries

Author

Xiaojun Ren

Subjects
Creative industries, Knowledge economy, Economics, Innovation theory, Innovation management, Marketing, Path analysis (statistics), China, Virtuous circle and vicious circle, Social economy
Abstract

Creative industry has become a necessary choice when social economy develops to a certain phase. It represents the future trend of newly-rising industries with knowledge economy, consumption culture and innovation theory as background. China?s creative industries, though still in the preparation phase and starting late, but with a higher start and faster movement, have become new growing hot spots in the national economy. Design can be defined as creative activities with specific purpose. The core of creative industry is innovation. So they are the same in nature. In this paper, from designing point of view and through the research of design nature and law of development, the author, starting with artistic design which is closely related to the creative industries, identifies the common nature of artistic design and creative industry, so as to extend and find out a promoting path of creative industries, and also to figure out the virtuous cycle enabling complementary and common development. In addition, the author wants to show the practical meaning of inclusion and coordination of the two through detailed examples and accurate data. Development of art and design is promoting the development of creative industries, and vise versa. Using references from current design promotion, combined with current development status, it will of great help to find out the path to development of creative industries with Chinese characteristics that adapt to China?s current development situation and fundamental realities.

Published
2008
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252. Irbesartan ameliorates diabetic nephropathy by reducing the expression of connective tissue growth factor and alpha-smooth-muscle actin in the tubulointerstitium of diabetic rats

Author

Xiaojun Ren, Guangju Guan, Gang Liu, and Gaohong Liu

Subjects
Blood Glucose, Male, medicine.medical_specialty, Connective tissue, Renal function, Tetrazoles, urologic and male genital diseases, Kidney, Diabetes Mellitus, Experimental, Diabetic nephropathy, chemistry.chemical_compound, Irbesartan, Internal medicine, Diabetes mellitus, medicine, Animals, Diabetic Nephropathies, Rats, Wistar, Serum Albumin, Pharmacology, Creatinine, business.industry, Biphenyl Compounds, Connective Tissue Growth Factor, General Medicine, medicine.disease, Actins, Rats, CTGF, medicine.anatomical_structure, Endocrinology, chemistry, Nephritis, Interstitial, business, Angiotensin II Type 1 Receptor Blockers, medicine.drug
Abstract

The effect of irbesartan on the expression of connective tissue growth factor (CTGF) and α-smooth-muscle actin (α-SMA) in the renal tubulointerstitium of diabetic rats was investigated in our study. Diabetes was induced in male Wistar rats by intraperitoneal administration of streptozotocin (STZ), 60 mg·kg–1 body weight. The rats were then randomized to a diabetic group (DM) and an irbesartan therapy group (DM + Irb). The normal group (non-DM) rats were administered only citrate buffer. At the end of the 16th week, blood glucose, kidney weight/body weight, urine albumin (UAlb) and creatinine clearance rate were determined. The renal histopathology was observed by light microscopy. Further biochemical analysis of CTGF and α-SMA was provided using real-time reverse transcription PCR, immunostaining and Western blotting techniques. Compared with the non-DM group, blood glucose, kidney weight/body weight, UAlb, creatinine clearance and interstitial fibrotic lesions were increased in the DM group (p < 0.01). Treatment with irbesartan improved these parameters except blood glucose. Compared with the non-DM group, expressions of CTGF and α-SMA in the renal tubulointerstitium were highly upregulated in the DM group (p < 0.01). Administration of irbesartan prevented the high expressions of CTGF and α-SMA in renal tissue of diabetic rats. These results indicated that irbesartan can protect the kidney of STZ-diabetic rats by reducing the expression of CTGF and α-SMA in the renal tubulointerstitium.

Published
2008

253. Changes in the distributions and dynamics of polycomb repressive complexes during embryonic stem cell differentiation

Author

Tom K. Kerppola, Claudius Vincenz, and Xiaojun Ren

Subjects
Cellular differentiation, Recombinant Fusion Proteins, Polycomb-Group Proteins, Protein–protein interaction, Chromodomain, Histones, Bimolecular fluorescence complementation, Histone H3, Mice, Bacterial Proteins, Polycomb-group proteins, Animals, Molecular Biology, Embryonic Stem Cells, Regulation of gene expression, Polycomb Repressive Complex 1, biology, Gene Expression Regulation, Developmental, Cell Differentiation, Cell Biology, Articles, Molecular biology, Repressor Proteins, Luminescent Proteins, Histone, biology.protein
Abstract

Polycomb group (PcG) transcription regulatory proteins maintain cell identity by sustained repression of numerous genes. The differentiation of embryonic stem (ES) cells induces a genome-wide shift in PcG target gene expression. We investigated the effects of differentiation and protein interactions on CBX family PcG protein localization and dynamics by using fluorescence imaging. In mouse ES cells, different CBX proteins exhibited distinct distributions and mobilities. Most CBX proteins were enriched in foci known as Polycomb bodies. Focus formation did not affect CBX protein mobilities, and the foci dispersed during ES cell differentiation. The mobilities of CBX proteins increased upon the induction of differentiation and decreased as differentiation progressed. The deletion of the chromobox, which mediates interactions with RING1B, prevented the immobilization of CBX proteins. In contrast, the deletion of the chromodomain, which can bind trimethylated lysine 27 of histone H3, had little effect on CBX protein dynamics. The distributions and mobilities of most CBX proteins corresponded to those of CBX-RING1B complexes detected by using bimolecular fluorescence complementation analysis. Epigenetic reprogramming during ES cell differentiation is therefore associated with global changes in the subnuclear distributions and dynamics of CBX protein complexes.

Published
2008

254. Loss optimization and thermal analysis of a heteropolar magnetic bearing for a vacuum turbo-molecular pump.

Author

Xiaojun Ren, Yun Le, Bangcheng Han, and Kun Wang

Subjects
*BEARINGS (Machinery), *PUMPING machinery, *FINITE element method, *MATHEMATICAL optimization, *GENETIC algorithms
Abstract

Compared with the traditional vacuum turbo-molecular pumps (TMPs) with oil-lubricated bearings, magnetically suspended TMPs can obtain an ultra-clean and ultra-high vacuum environment. Considering the poor heat dissipation condition of rotor and miniaturization of industrial applications, this paper focuses on loss optimization and thermal analysis of a heteropolar magnetic bearing (HeMB) for a vacuum TMP. Loss and mass of HeMB were minimized with multi-objective genetic algorithm optimization. Thermal performance predictive calculation is conducted by analytical model and by finite element method (FEM), respectively. To verify the optimization design and anylysis, the relative tests were implemented on a prototype. For the mechanical and electrical products applied in vacuum, loss optimization and thermal analysis at design stage are very important to the implementation of the system performance. [ABSTRACT FROM AUTHOR]

Published
2017
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255. Accelerated or hyperfractionated radiotherapy for esophageal carcinoma: a meta-analysis of randomized controlled trials.

Author

Yingyu Liu, Changgui Kou, Yingying Su, Yangyu Zhang, Yueyue You, Lili Zhang, Mohan Wang, Yingli Fu, Xiaojun Ren, and Yanming Yang

Subjects
RADIOTHERAPY, DOSE fractionation, DIAGNOSIS of esophageal cancer, META-analysis, ACUTE radiation syndrome, TRACHEITIS, THERAPEUTICS
Abstract

Objective: The goal of this study was to evaluate the efficacy and safety of modified (accelerated and/or hyperfractionated) radiotherapy in the treatment of esophageal carcinoma, compared with conventional radiotherapy. Methods: Studies published in the PubMed, Cochrane Library, EMBASE, CBM, VIP, CNKI and Wanfang databases in the most recent two decades were searched for use in this meta-analysis. Only randomized controlled trials were included. The heterogeneity analysis and calculation of the pooled odds ratio (OR) were performed using RevMan 5.3 software. The assessment of publication bias and sensitivity analyses was conducted using Stata 13.0 software. Results: Twenty trials with a total of 1,742 Chinese patients who met the inclusion criteria were included. The pooled results showed that modified radiotherapy improved the response rate compared with conventional schedules (OR =3.90, 95% confidence interval [CI]: 2.47-6.16, P,0.001). Favorable results were observed for the 1-year (OR =2.58, 95% CI: 2.05-3.26, P,0.001), 3-year (OR =2.30, 95% CI: 1.83-2.89, P,0.001) and 5-year (OR =2.36, 95% CI: 1.74-3.21, P,0.001) overall survival and for the 1-year (OR =2.46, 95% CI: 1.72-3.51, P,0.001), 3-year (OR =2.08, 95% CI: 1.49-2.90, P,0.001) and 5-year (OR =2.15, 95% CI: 1.38-3.34, P,0.001) overall local control rate in the modified fractionation radiotherapy group. However, the altered radiotherapy increased the risk of acute radiation esophagitis (OR =1.70, 95% CI: 1.27-2.28, P,0.001) and acute radiation tracheitis (OR =1.47, 95% CI: 1.09-1.99, P=0.01). No significant differences in the risk of esophageal perforation (OR =1.30, 95% CI: 0.51-3.32, P=0.58) or esophagorrhagia (OR =0.88, 95% CI: 0.41-1.88, P=0.74) were found between the two groups. Conclusion: Chinese patients with squamous cell esophagus carcinomas gained a significant benefit in terms of the response rate, survival and local control rates from the modified fractionation radiotherapy, but also had an increased risk of acute radiation reactions. Otherwise, there was no observed statistically significant difference in terms of early adverse reactions. [ABSTRACT FROM AUTHOR]

Published
2017
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256. Fluorescence studies of single biomolecules

Author

Shankar Balasubramanian, Xiaojun Ren, Liming Ying, David Klenerman, and Haitao Li

Subjects
RNA metabolism, chemistry.chemical_classification, Protein Folding, Time Factors, Chemistry, Protein Conformation, Biomolecule, Lasers, Excitation beam, Normal Distribution, Nanotechnology, Laser, Biochemistry, Fluorescence, law.invention, Förster resonance energy transfer, Spectrometry, Fluorescence, law, Spectrophotometry, Fluorescence Resonance Energy Transfer, Humans, RNA, Telomerase, Fluorescent Dyes
Abstract

Single-molecule fluorescence has the capability to detect properties buried in ensemble measurements and, hence, provides new insights about biological processes. Ratiometric methods are normally used to reduce the effects of excitation beam inhomogeneity. Fluorescence resonance energy transfer is widely used but there are problems in inserting the fluorophores in the correct position on the biomolecule, particularly if the structure is not known. We have recently developed two-colour coincidence single-molecule fluorescence that addresses this problem. This method can be used to determine quantitatively the multimerization states of biomolecules, in solution without separation. The future prospects of single-molecule fluorescence as applied to biological molecules are discussed.

Published
2004

257. A selenium-containing single-chain abzyme with potent antioxidant activity

Author

Delin, You, Xiaojun, Ren, Yan, Xue, Guimin, Luo, Tongshu, Yang, and Jiacong, Shen

Subjects
Electron Transport Complex IV, Glutathione Peroxidase, Oxidative Stress, Selenium, Animals, Antibodies, Catalytic, Cattle, Lipid Peroxidation, Antioxidants, Mitochondria, Heart
Abstract

Reactive oxygen species (ROS) are products of normal metabolic activities and are thought to be the cause of many diseases. A selenium-containing single-chain abzyme 2F3 (Se-2F3-scFv) that imitates glutathione peroxidase has been produced which has the capacity to remove ROS. To evaluate the antioxidant ability of Se-2F3-scFv, we constructed a ferrous sulfate/ascorbate (Vc/Fe2+)-induced mitochondrial damage model system and investigated the capacity of Se-2F3-scFv to protect mitochondria from oxidative damage. Se-2F3-scFv markedly decreased mitochondrial swelling, inhibited lipid peroxidation, and maintained the activity of cytochrome c oxidase, in comparison with Ebselen, a well-studied glutathione peroxidase mimic, indicating that Se-2F3-scFv has potential for treating diseases mediated by ROS.

Published
2003

258. Towards more efficient glutathione peroxidase mimics: substrate recognition and catalytic group assembly

Author

Xiaojun Ren, Jiacong Shen, Ying Mu, Guimin Luo, and Junqiu Liu

Subjects
Protective Agents, Biochemistry, Catalysis, Substrate Specificity, chemistry.chemical_compound, Drug Discovery, Animals, Humans, Binding site, Cells, Cultured, Pharmacology, chemistry.chemical_classification, Glutathione Peroxidase, Binding Sites, Selenocysteine, biology, Glutathione peroxidase, Organic Chemistry, Molecular Mimicry, Glutathione, Abzyme, Oxidative Stress, chemistry, biology.protein, Molecular Medicine, Enzyme mimic, Selenoprotein, Reactive Oxygen Species, Peroxidase
Abstract

Glutathione peroxidase (GPX) is a well-known selenoenzyme that functions as an antioxidant and catalyzes the reduction of harmful peroxide by glutathione and protects cells against oxidative damage. Because many diseases are related to oxidative stress, GPX is an ancient foe of many diseases. Antioxidants are very useful for biological bodies, and considerable effort has been spent to find compounds that could imitate the properties of GPX. This paper reviews GPX mimics developed so far and describes a new, more effective strategy for fabricating them. Although many GPX mimics have been made, they possess serious disadvantages: low activity, low solubility in water, and, in some cases, toxicity. In order to overcome these drawbacks, we have proposed a new strategy of imitating GPX. First, a receptor with a substrate binding site is generated. Next, a catalytic group is incorporated into the receptor near the substrate binding site, allowing the catalytic group access to the functional group of the substrate. Finally, a highly efficient enzyme mimic is obtained. Using this strategy, we successfully fabricated GPX mimics that use antibodies, cyclodextrins, some enzymes and proteins as receptors and chemical modification to incorporate the catalytic group, selenocysteine (Sec). The general principle of combining a functional group involved in catalysis with a specific binding site for the substrate is an approach that could be applied to the generation of other efficient semisynthetic biocatalysts. We describe the antioxidant activities of these GPX mimics and the reasons of their being promising candidates for medicinal applications.

Published
2003

259. UV-B induced keratinocyte apoptosis is blocked by 2-selenium-bridged beta-cyclodextrin, a GPX mimic

Author

Weijia Li, Junqiu Liu, Guanghui Jin, Xiaojun Ren, Jiacong Shen, Ying Mu, Shaowu Lv, Ganglin Yan, and Guimin Luo

Subjects
Bridged-Ring Compounds, Keratinocytes, Programmed cell death, Antioxidant, Ultraviolet Rays, medicine.medical_treatment, Biophysics, Apoptosis, Cell Line, Lipid peroxidation, chemistry.chemical_compound, Organoselenium Compounds, medicine, Humans, Radiology, Nuclear Medicine and imaging, chemistry.chemical_classification, Reactive oxygen species, Cyclodextrins, Glutathione Peroxidase, Radiation, Radiological and Ultrasound Technology, Chemistry, Cell growth, Glutathione peroxidase, Molecular Mimicry, beta-Cyclodextrins, Free Radical Scavengers, Cell biology, Biochemistry, Lipid Peroxidation, Signal transduction, Reactive Oxygen Species, Signal Transduction
Abstract

Cell proliferation and cell death of keratinocytes are tightly regulated to ensure epidermal homeostasis. UV-B induces keratinocyte apoptosis. UV-B also induces lipid peroxidation of keratinocytes to increase their amount of malondialdehyde (MDA). These phenomena can be explained by the production of reactive oxygen species (ROS) induced by UV-B radiation. We synthesized 2-selenium-bridged β-cyclodextrin (2-SeCD) to imitate glutathione peroxidase (GPX), an important antioxidant and established a damage system, in which keratinocytes can be damaged by Ultraviolet B (UV-B) radiation. Using this damage system we studied 2-SeCD protection of keratinocytes against injury induced by UV-B. Experimental results showed that 2-SeCD could protect keratinocytes from apoptosis. Moreover, 2-SeCD inhibits lipid peroxidation of keratinocytes and scavenges ROS. 2-SeCD inhibits the UV-B induced apoptotic signal transduction. This antiapoptotic mechanism may be partly related to the elimination of hydrogen peroxide.

Published
2003

260. A semisynthetic glutathione peroxidase with high catalytic efficiency. Selenoglutathione transferase

Author

Xiaojun, Ren, Per, Jemth, Philip G, Board, Guimin, Luo, Bengt, Mannervik, Junqiu, Liu, Kun, Zhang, and Jiacong, Shen

Subjects
Glutathione Peroxidase, Kinetics, Selenium, Binding Sites, Serine, Antibodies, Monoclonal, Hydrogen Peroxide, Protein Engineering, Glutathione, Oxidation-Reduction, Catalysis, Glutathione Transferase, Substrate Specificity
Abstract

Glutathione peroxidase (GPX) protects cells against oxidative damage by catalyzing the reduction of hydroperoxides by glutathione (GSH). GPX therefore has potential therapeutic value as an antioxidant, but its pharmacological development has been limited because GPX uses a selenocysteine as its catalytic group and it is difficult to generate selenium-containing proteins with traditional recombinant DNA technology. Here, we show that naturally occurring proteins can be modified to generate GPX activity. The rat theta-class glutathione transferase T2-2 (rGST T2-2) presents an ideal scaffold for the design of a novel GPX catalyst because it already binds GSH and contains a serine close to the substrate binding site, which can be chemically modified to bind selenium. The modified Se-rGST T2-2 efficiently catalyzes the reduction of hydrogen peroxide, and the GPX activity surpasses the activities of some natural GPXs.

Published
2002

261. Cloning and expression of a single-chain catalytic antibody that acts as a glutathione peroxidase mimic with high catalytic efficiency

Author

Xiaojun REN, Shujuan GAO, Delin YOU, Hualiang HUANG, Zi LIU, Ying MU, Junqiu LIU, Yan ZHANG, Ganglin YAN, Guimin LUO, Tongshu YANG, and Jiacong SHEN

Subjects
Glutathione Peroxidase, Protein Folding, DNA, Complementary, Base Sequence, Genetic Vectors, Molecular Sequence Data, Antibodies, Monoclonal, Gene Expression, Antibodies, Catalytic, Cell Biology, In Vitro Techniques, Protein Engineering, Biochemistry, Recombinant Proteins, Kinetics, Mice, Selenium, Catalytic Domain, Escherichia coli, Animals, Amino Acid Sequence, Cloning, Molecular, Molecular Biology, Research Article, DNA Primers
Abstract

Glutathione peroxidase (GPX) has a powerful role in scavenging reactive oxygen species. In previous papers we have developed a new strategy for generating abzymes: the monoclonal antibody with a substrate-binding site is first prepared, then a catalytic group is incorporated into the monoclonal antibody's binding site by using chemical mutation [Luo, Zhu, Ding, Gao, Sun, Liu, Yang and Shen (1994) Biochem. Biophys. Res. Commun. 198, 1240-1247; Ding, Liu, Zhu, Luo, Zhao and Ni (1998) Biochem. J. 332, 251-255]. Since then we have established a series of catalytic antibodies capable of catalysing the decomposition of hydroperoxides by GSH. The monoclonal antibody 2F3 was raised against GSH-S-2,4-dinitrophenyl t-butyl ester and exhibited high catalytic efficiency, exceeding that of rabbit liver GPX, after chemical mutation. To produce pharmaceutical proteins and to study the reason why it exhibits high catalytic efficiency, we sequenced, cloned and expressed the variable regions of 2F3 antibody as a single-chain Fv fragment (2F3-scFv) in different bacterial strains. The amounts of 2F3-scFv proteins expressed from JM109 (DE3), BL21 (DE3), and BL21 (coden plus) were 5-10%, 15-20% and 25-30% of total bacterial proteins respectively. The 2F3-scFv was expressed as inclusion bodies, purified in the presence of 8 M urea by Co(2+)-immobilized metal-affinity chromatography (IMAC) and renatured to the active form in vitro by gel filtration. The binding constants of the active 2F3-scFv for GSH and GSSG were 2.46 x 10(5) M(-1) and 1.03 x 10(5) M(-1) respectively, which were less by one order of magnitude than that of the intact 2F3 antibody. The active 2F3-scFv was converted into selenium-containing 2F3-scFv (Se-2F3-scFv) by chemical modification of the reactive serine; the GPX activity of the Se-2F3-scFv was 3394 units/micromol, which approaches the activity of rabbit liver GPX.

Published
2001

262. A graphene oxide-based immobilized PNGase F reagent for highly efficient N-glycan release and MALDI-TOF MS profiling

Author

Peibin Qin, Hui Yan, Wei Tong, Haihong Bai, Xiaojun Ren, Yiting Pan, Xiaohong Qian, Shanshan Deng, Rugang Zhong, and Weijie Qin

Subjects
PNGase F, chemistry.chemical_classification, Glycan, Chromatography, biology, Chemistry, Graphene, General Chemical Engineering, General Engineering, Peptide, Analytical Chemistry, law.invention, carbohydrates (lipids), Matrix-assisted laser desorption/ionization, Enzyme, Biochemistry, law, Reagent, biology.protein, Glycoprotein
Abstract

Protein N-glycosylation plays an important role in a variety of biological processes, and unusual changes in glycan structures are often correlated with various pathological states. Therefore, N-glycan profiling not only plays a vital role in the mechanism study of biological processes but also contributes to the discovery of biomarkers for early disease diagnosis. However, the conventional in-solution release of N-glycans by free endoglycosidases, such as peptide N-glycosidase F (PNGase F), suffers from several drawbacks, including prolonged incubation time, possible incomplete digestion and high cost due to the non-reusability of the enzyme. Herein, we report a novel graphene oxide (GO)-based immobilized PNGase F reagent for fast and highly efficient N-glycan release and glycoform profiling of glycoproteins. To create this reagent, PNGase F was attached to the GO surface via carbodiimide-activated amidation. The ultra-high surface area of GO allows for high loading with PNGase F and significantly facilitates the deglycosylation process. Highly efficient N-glycan release of ribonuclease B and asialofetuin was achieved with this reagent within 2 min. Furthermore, the successful application of our GO-based immobilized PNGase F in the N-glycan release of the human plasma glycoproteome was demonstrated by reproducible N-glycan identification using MALDI-TOF MS.

Published
2014
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263. Effect of L-thyroxine treatment versus a placebo on serum lipid levels in patients with sub-clinical hypothyroidism.

Author

XUE LI, ZHAOWEI MENG, QIANG JIA, and XIAOJUN REN

Subjects
THYROXINE, BLOOD lipids, HYPOTHYROIDISM treatment, LOW density lipoproteins, PLACEBOS, THERAPEUTICS
Abstract

Sub-clinical hypothyroidism is a common disease and whether L-thyroxine replacement treatment improves serum lipid levels in affected patients remains controversial. Thus, the aim of the present meta-analysis was to assess the effect of L-thyroxine therapy on serum lipid levels in sub-clinical hyperthyroidism. Relevant randomized controlled trials (RCTs) containing continuous data, published until July 2015 were retrieved from the Cochrane Library, PubMed, Medline, Google Scholar and Embase databases and subjected to meta-analysis using Review Manager software version 5.2 (The Nordic Cochrane Centre, Copenhagen, Denmark). Seven RCTs comprising 319 patients were included. The overall methodological quality of the RCTs was good. Statistical analysis revealed that serum low-density lipoprotein-cholesterol (LDL-C) levels were significantly decreased after L-thyroxine treatment [mean difference (MD): -0.23; 95% confidence interval: -0.44, -0.03; P=0.02], while changes of total cholesterol (TC), triglyceride (TG) and high-density lipoprotein- cholesterol (HDL-C) were not significant (MD: -0.18, P=0.09; MD: -0.02, P=0.78; and MD: -0.06, P=0.14, respectively). In conclusion, the meta-analysis performed in the present study revealed that compared with placebo treatment, L-thyroxine significantly improved serum LDL-C levels in patients with sub-clinical hypothyroidism, while not significantly affecting TC, TG and HDL-C levels. [ABSTRACT FROM AUTHOR]

Published
2016
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265. Chronic Lead Exposure Alters Transthyretin Concentration in Rat Cerebrospinal Fluid: The Role of the Choroid Plexus

Author

Xiaojun Ren, Joseph H. Graziano, Wei Zheng, Huan Shen, William S. Blaner, and Qiuqu Zhao

Subjects
Male, medicine.medical_specialty, Cations, Divalent, Administration, Oral, Toxicology, Drug Administration Schedule, Article, Rats, Sprague-Dawley, Cerebrospinal fluid, Internal medicine, medicine, Organometallic Compounds, Animals, Prealbumin, CSF albumin, Pharmacology, Plexus, Analysis of Variance, biology, Dose-Response Relationship, Drug, Chemistry, Body Weight, Radioimmunoassay, Cations, Monovalent, Rats, Transthyretin, Dose–response relationship, Endocrinology, Lead, Metals, Toxicity, Choroid Plexus, biology.protein, Choroid plexus
Abstract

The choroid plexus, which is responsible for the maintenance of the biochemical milieu of the cerebrospinal fluid (CSF), avidly sequesters Pb. In order to test the hypothesis that chronic Pb exposure may impair choroid plexus function, male weanling Sprague-Dawley rats were exposed to Pb in drinking water at doses of 0, 50, or 250 micrograms Pb/ml (as Pb acetate) for 30, 60, or 90 days. The function of the choroid plexus was assessed as reflected by CSF concentrations of transthyretin (TTR, a major CSF protein manufactured by brain choroid plexus) and CSF essential metal ions (Ca2+, Mg2+, K+, and Na+). TTR concentrations were determined by radioimmunoassay using a monospecific rabbit anti-rat TTR polyclonal antibody, and CSF metal ions analyzed by flame atomic absorption spectrophotometry. Two-way ANOVA of CSF TTR concentrations revealed highly significant dose (p < 0.0001), time (p < 0.0223), and dose-by-time effects (p < 0.0379). Moreover, the percentage of reduction of CSF TTR was directly correlated with Pb concentrations in the choroid plexus (r = 0.703, p < 0.05). Pb exposure significantly increased CSF concentrations of Mg2+, but did not markedly altered CSF concentrations of Ca2+, K+, and Na+. Histopathologic examination under the light microscope did not show distinct alterations of plexus structure in Pb-treated rats. Since TTR is responsible for transport of thyroid hormones to the developing brain, we postulate that the depression of choroid plexus TTR production (and/or secretion) by Pb may impair brain development in young animals by depriving the CNS of thyroid hormones.

Published
1996

269. Erratum: Single-molecule analysis of human telomerase monomer

Author

Shankar Balasubramanian, Xiaojun Ren, David Klenerman, Rosalind Codrington, David Alves, Haitao Li, and Angel Orte

Subjects
chemistry.chemical_compound, Human telomerase, Monomer, Column (typography), Nat, Chemistry, Stereochemistry, Molecule, Cell Biology, Molecular Biology, Fusion protein
Abstract

Nat. Chem. Biol. 4, 287–289 (2008); published online 6 April 2008; corrected after print 1 May 2008 In the version of this article initially published, parentheses were missing around covalently attached domains in fusion proteins. Also, in the first two lines of the left column of page 288, “hTERT-YFP” should have read “YFP-hTERT” for consistency with the rest of the manuscript.

Published
2008
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273. SaaS Intelligent Customization Model Based on Tenancy History.

Author

Xiaojun Ren, Yongqing Zheng, and Lanju Kong

Subjects
SOFTWARE as a service, CUSTOMIZATION, INTELLIGENT control systems, ARTIFICIAL intelligence, LANDLORD-tenant relations, METADATA
Abstract

SaaS (Software as a Service) applications have to be customizable to fulfill specific business needs of tenants. The tenant can customize with the same application more than once by using customization templates. Preservation of history tenancy metadata not only can contribute to the tenant mistakes recovery or as a starting point for next customization, but also can be used to adjust templates. In order to improve the convenience of on-premise customization, shorten the tenants' customization time, improved QoS, we propose a method for adjusting template dynamically and propose the intelligent recommendation method based on tenancy history to support new tenants to deploy using information from existing deployed SaaS applications. The former method can adjust according to the update of tenancy history metadata, when the requirements of tenants change, the template update accordingly by analyzing tenancy history metadata from Graphic User Interface (GUI), workflow, service, and data layer. The updated templates will support customization in a cost effective way, in addition, can be provided to the Independent Software Developers (ISV) as a reference in next application upgrade. Finally, experiments show that template adjustment algorithm in the application is feasible and efficient. [ABSTRACT FROM AUTHOR]

Published
2013

274. Irbesartan Ameliorates Diabetic Nephropathy by Reducing the Expression of Connective Tissue Growth Factor and Alpha-Smooth-Muscle Actin in the Tubulointerstitium of Diabetic Rats.

Author

Xiaojun Ren, Guangju Guan, Gang Liu, and Gaohong Liu

Subjects
*KIDNEY diseases, *DIABETES, *ACTIN, *BLOOD sugar, *STREPTOZOTOCIN
Abstract

The effect of irbesartan on the expression of connective tissue growth factor (CTGF) and α-smooth-muscle actin (α-SMA) in the renal tubulointerstitium of diabetic rats was investigated in our study. Diabetes was induced in male Wistar rats by intraperitoneal administration of streptozotocin (STZ), 60 mg·kg–1 body weight. The rats were then randomized to a diabetic group (DM) and an irbesartan therapy group (DM + Irb). The normal group (non-DM) rats were administered only citrate buffer. At the end of the 16th week, blood glucose, kidney weight/body weight, urine albumin (UAlb) and creatinine clearance rate were determined. The renal histopathology was observed by light microscopy. Further biochemical analysis of CTGF and α-SMA was provided using real-time reverse transcription PCR, immunostaining and Western blotting techniques. Compared with the non-DM group, blood glucose, kidney weight/body weight, UAlb, creatinine clearance and interstitial fibrotic lesions were increased in the DM group (p < 0.01). Treatment with irbesartan improved these parameters except blood glucose. Compared with the non-DM group, expressions of CTGF and α-SMA in the renal tubulointerstitium were highly upregulated in the DM group (p < 0.01). Administration of irbesartan prevented the high expressions of CTGF and α-SMA in renal tissue of diabetic rats. These results indicated that irbesartan can protect the kidney of STZ-diabetic rats by reducing the expression of CTGF and α-SMA in the renal tubulointerstitium. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Published
2009
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275. Analysis of Human Telomerase Activity and Function by Two Color Single Molecule Coincidence Fluorescence Spectroscopy.

Author

Xiaojun Ren, Haitao Li, Clarke, Richard W., Alves, David A., Liming Ying, Klenerman, David, and Balasubramanian, Shankar

Subjects
*TELOMERASE, *DNA polymerases, *FLUORESCENCE spectroscopy, *HUMAN molecular genetics, *HUMAN genetics
Abstract

Telomerase is a nonclassical DNA polymerase that uses its integral RNA as a template to synthesize telomeric repeats onto chromosome ends. The molecular mechanism of telomerase is unique and involves a translocation step after the synthesis of each telomeric repeat. To directly measure the enzymatic turnover of substrate and the efficiency of the translocation step we have extended our two- color single molecule fluorescence coincidence method (Anal.Chem. 2003, 75, 1664-1670). The method employs Cy5-dATP incorporation into a DNA primer that has been prelabeled with a reference fluorophore. Measurements are performed in the single molecule regime and products, which necessarily have both fluorophores, are excited by two independent lasers, and give rise to coincident events. By counting the number of coincident events and using the coincidence detection efficiency, it is possible to determine the number of the extended products generated by attomole quantities of telomerase, without separation or the use of PCR or radioactivity. Histograms of the logarithms of the ratios of the Cy5 to the reference fluorophore fluorescence can be used to determine the length distribution of the products and hence the enzyme processivity. The mean processivity obtained from the single molecule fluorescence coincidence assay is 0.32 ± 0.04, in good agreement with the value of 0.37 ± 0.05 derived from the direct radioactive assay approach. The function of the alignment domain of human telomerase RNA in sustaining catalytic activity in vitro has been reevaluated using this method. Together with our previous results (Nucleic Acids Res. 2002, 30, 4470-4480) these experiments identify the essential residues in the alignment domain of human telomerase RNA that contribute to the activity and processivity of telomerase. [ABSTRACT FROM AUTHOR]

Published
2006
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276. Single-molecule analysis of human telomerase monomer.

Author

Alves, David, Haitao Li, Codrington, Rosalind, Orte, Angel, Xiaojun Ren, Klenerman, David, and Balasubramanian, Shankar

Subjects
TELOMERASE, NUCLEOPROTEINS, MONOMERS, RNA, PROTEINS, BIOCHEMISTRY
Abstract

Human telomerase is a ribonucleoprotein that is minimally comprised of protein (hTERT) and RNA (hTR) components. We have applied single-molecule fluorescence two-color coincidence detection to characterize complex formation between fluorophore-labeled components in solution. By systematic labeling and in vitro assembly of hTERT, hTR and telomerase's DNA substrate, we have established that catalytically functional human telomerase comprises a stable hTERT:hTR:substrate interaction in a 1:1:1 absolute stoichiometry. [ABSTRACT FROM AUTHOR]

Published
2008
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278. Changes in the Distributions and Dynamics of Polycomb Repressive Complexes during Embryonic Stem Cell Differentiation.

Author

Xiaojun Ren, Vincenz, Claudius, and Kerppola, Tom K.

Subjects
*EMBRYONIC stem cells, *CELL differentiation, *TRANSCRIPTION factors, *GENOMES, *GENE expression
Abstract

Polycomb group (PcG) transcription regulatory proteins maintain cell identity by sustained repression of numerous genes. The differentiation of embryonic stem (ES) cells induces a genome-wide shift in PcG target gene expression. We investigated the effects of differentiation and protein interactions on CBX family PcG protein localization and dynamics by using fluorescence imaging. In mouse ES cells, different CBX proteins exhibited distinct distributions and mobilities. Most CBX proteins were enriched in foci known as Polycomb bodies. Focus formation did not affect CBX protein mobilities, and the foci dispersed during ES cell differentiation. The mobilities of CBX proteins increased upon the induction of differentiation and decreased as differentiation progressed. The deletion of the chromobox, which mediates interactions with RING1B, prevented the immobilization of CBX proteins. In contrast, the deletion of the chromodomain, which can bind trimethylated lysine 27 of histone H3, had little effect on CBX protein dynamics. The distributions and mobilities of most CBX proteins corresponded to those of CBX-RING1B complexes detected by using bimolecular fluorescence complementation analysis. Epigenetic reprogramming during ES cell differentiation is therefore associated with global changes in the subnuclear distributions and dynamics of CBX protein complexes. [ABSTRACT FROM AUTHOR]

Published
2008
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279. Nuclear condensates of the Polycomb protein chromobox 2 (CBX2) assemble through phase separation.

Author

Tatavosian, Roubina, Kent, Samantha, Brown, Kyle, Tingting Yao, Huy Nguyen Duc, Thao Ngoc Huynh, Chao Yu Zhen, Ma, Brian, Haobin Wang, and Xiaojun Ren

Subjects
*POLYCOMB group proteins, *CHROMATIN, *CHROMOSOMES, *NUCLEOPROTEINS, *BACTERIAL chromatin, *TRANSCRIPTION factors, *BOSE-Einstein condensation
Abstract

Polycomb group (PcG) proteins repress master regulators of development and differentiation through organization of chromatin structure. Mutation and dysregulation of PcG genes cause developmental defects and cancer. PcG proteins form condensates in the cell nucleus, and these condensates are the physical sites of PcG-targeted gene silencing via formation of facultative heterochromatin. However, the physiochemical principles underlying the formation of PcG condensates remain unknown, and their determination could shed light on how these condensates compact chromatin. Using fluorescence live-cell imaging, we observed that the Polycomb repressive complex 1 (PRC1) protein chromobox 2 (CBX2), a member of the CBX protein family, undergoes phase separation to form condensates and that the CBX2 condensates exhibit liquid-like properties. Using site-directed mutagenesis, we demonstrated that the conserved residues of CBX2 within the intrinsically disordered region (IDR), which is the region for compaction of chromatin in vitro, promote the condensate formation both in vitro and in vivo.We showed that the CBX2 condensates concentrate DNA and nucleosomes. Using genetic engineering,wereport that trimethylation of Lys-27 at histone H3 (H3K27me3), a marker of heterochromatin formation produced by PRC2, had minimal effects on the CBX2 condensate formation. We further demonstrated that the CBX2 condensate formation does not require CBX2--PRC1 subunits; however, the condensate formation of CBX2--PRC1 subunits depends on CBX2, suggesting a mechanism underlying the assembly of CBX2--PRC1 condensates. In summary, our results reveal that PcG condensates assemble through liquid--liquid phase separation (LLPS) and suggest that phase-separated condensates can organize PcGbound chromatin. [ABSTRACT FROM AUTHOR]

Published
2019
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280. Distinct Cellular Assembly Stoichiometry of Polycomb Complexes on Chromatin Revealed by Single-molecule Chromatin Immunoprecipitation Imaging.

Author

Tatavosian, Roubina, Chao Yu Zhen, Huy Nguyen Duc, Balas, Maggie M., Johnson, Aaron M., and Xiaojun Ren

Subjects
*STOICHIOMETRY, *POLYCOMB group proteins, *CHROMATIN, *IMMUNOPRECIPITATION, *NUCLEOPROTEINS
Abstract

Epigenetic complexes play an essential role in regulating chromatin structure, but information about their assembly stoichiometry on chromatin within cells is poorly understood. The cellular assembly stoichiometry is critical for appreciating the initiation, propagation, and maintenance of epigenetic inheritance during normal development and in cancer. By combining genetic engineering, chromatin biochemistry, and single-molecule fluorescence imaging, we developed a novel and sensitive approach termed single-molecule chromatin immunoprecipitation imaging (Sm-ChIPi) to enable investigation of the cellular assembly stoichiometry of epigenetic complexes on chromatin. Sm-ChIPi was validated by using chromatin complexes with known stoichiometry. The stoichiometry of subunits within a polycomb complex and the assembly stoichiometry of polycomb complexes on chromatin have been extensively studied but reached divergent views. Moreover, the cellular assembly stoichiometry of polycomb complexes on chromatin remains unexplored. Using Sm-ChIPi, we demonstrated that within mouse embryonic stem cells, one polycomb repressive complex (PRC) 1 associates with multiple nucleosomes, whereas two PRC2s can bind to a single nucleosome. Furthermore, we obtained direct physical evidence that the nucleoplasmic PRC1 is monomeric, whereas PRC2 can dimerize in the nucleoplasm. We showed that ES cell differentiation induces selective alteration of the assembly stoichiometry of Cbx2 on chromatin but not other PRC1 components. We additionally showed that the PRC2-mediated trimethylation of H3K27 is not required for the assembly stoichiometry of PRC1 on chromatin. Thus, these findings uncover that PRC1 and PRC2 employ distinct mechanisms to assemble on chromatin, and the novel Sm-ChIPi technique could provide single-molecule insight into other epigenetic complexes. [ABSTRACT FROM AUTHOR]

Published
2015
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281. Aryl Thiol Substrate 3-Carboxy-4-Nitrobenzenethiol Strongly Stimulating Thiol Peroxidase Activity of Glutathione Peroxidase Mimic 2, 2'-Ditellurobis(2-Deoxy-β-Cyclodextrin).

Author

Zeyuan Dong, Junqiu Liu, Shizhong Mao, Xin Huang, Bing Yang, Xiaojun Ren, Guimin Luo, and Jiacong Shen

Subjects
*GLUTATHIONE, *PEROXIDASE, *THIOLS, *CYCLODEXTRINS, *DICUMYL peroxide, *CATALYSIS
Abstract

Artificial glutathione peroxidase (GPx) model 2, 2'-ditellurobis(2-deoxy-β-cyclodextrin) (2-TeCD) which has the desirable properties exhibited high substrate specificity and remarkably catalytic efficiency when 3-carboxy-4-nitrobenzenethiol (ArSH) was used as a preferential thiol substrate. The complexation of ArSH with β-cyclodextrin was investigated through UV spectral titrations, fluorescence spectroscopy, 1H NMR and molecular simulation, and these results indicated that ArSH fits well to the size of the cavity of β-cyclodextrin. Furthermore, 2-TeCD was found to catalyze the reduction of cumene peroxide (CuOOH) by ArSH 200 000-fold more efficiently than diphenyl diselenide (PhSeSePh). Its steady-state kinetics was studied and the second rate constant kmax/KArSH was found to be 1.05 × 107 M-1 min-1 and similar to that of natural GPx. Moreover, the kinetic data revealed that the catalytic efficiency of 2-TeCD depended strongly upon the competitive recognition of both substrates for 2-TeCD. The catalytic mechanism of 2-TeCD catalysis agreed well with a ping-pong mechanism, in analogy with natural GPx, and might exert its thiol peroxidase activity via tellurol, tellurenic acid, and tellurosulfide. [ABSTRACT FROM AUTHOR]

Published
2004
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