The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
P Zabel - One of the best experts on this subject based on the ideXlab platform.
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tumor necrosis factor α 308 promoter gene polymorphism and increased tumor necrosis factor serum Bioactivity in farmer s lung patients
American Journal of Respiratory and Critical Care Medicine, 2001Co-Authors: Bernhard Schaaf, Ulrike Seitzer, Vera Pravica, Sven P Aries, P ZabelAbstract:Hypersensitivity pneumonitis (HP) represents an immunologic reaction of the pulmonary parenchyma to an inhaled agent. Since tumor necrosis factor (TNF)- α is thought to be involved in the pathogenesis of HP, and polymorphisms in the TNF genes have been associated with variations in the production of TNF- α , we investigated the serum Bioactivity and genotype of TNF in HP. TNF Bioactivity was measured after hay dust challenge in eight patients with farmer's lung (Group A) and in 12 healthy, sensitized (antibody-positive) controls (Group B). Genotyping for the − 308 TNF- α promoter polymorphism and the TNF- β intron 1 gene polymorphism was performed in 20 patients with farmer's lung, 25 patients with pigeon breeder's lung, and 216 controls. TNF Bioactivity increased in Group A at 4 to 10 h after hay dust challenge, but not in Group B (p < 0.05). The frequency for the TNFA2 allele, a genotype associated with high TNF- α production in vitro, was significantly higher in farmer's lung patients (frequency [f] = ...
Tao Hu - One of the best experts on this subject based on the ideXlab platform.
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conjugation with eight arm peg markedly improves the in vitro activity and prolongs the blood circulation of staphylokinase
Bioconjugate Chemistry, 2018Co-Authors: Fangbing Qi, Chunyang Hu, Weili Yu, Tao HuAbstract:Staphylokinase (SAK) is a profibrinolytic protein and can be used for therapy of acute myocardial infarction and coronary thrombosis. However, SAK suffers from a short serum half-life time (∼6 min) that limits its clinical application. PEGylation prolongs the half-life time of SAK, whereas it significantly decreases the Bioactivity of SAK for the steric shielding effect of PEG. To improve the Bioactivity and prolong the half-life time of SAK, 8-arm PEG maleimide (8-arm PEG) was used for conjugation of multiple SAK molecules in one entity. C terminus of SAK was engineered with cysteine residue, followed by reaction with the maleimide moieties of 8-arm PEG to obtain the conjugate (SAKp-PEG). Conjugation with 8-arm PEG retained the secondary structure of SAK, slightly perturbed the tertiary structure of SAK, and essentially maintained its in vitro Bioactivity by the multivalence of SAK. Conjugation with 8-arm PEG increased the hydrodynamic volume and thus significantly prolonged the half-life time of SAK. SA...
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heat treatment increases the Bioactivity of c terminally pegylated staphylokinase
Process Biochemistry, 2014Co-Authors: Shaoyang Ji, Qimeng Mu, Tao HuAbstract:PEGylation can effectively improve the therapeutic potential of staphylokinase (SAK), a thrombolysis agent for therapy of myocardial infarction. However, polyethylene glycol (PEG) can sterically shield SAK and drastically decrease its Bioactivity. In the present study, N-terminally PEGylated SAKs.(5 and 20 kDa PEG), C-terminally PEGylated SAKs with phenyl linker and the ones with amyl linker (5 and 20 kDa PEG) were prepared. The effects of the PEG length, the PEGylation site and linker chemistry on the Bioactivity of the heat-treated PEGylated SAK were investigated. Heat treatment at 70 C for 2 h can improve the Bioactivity of the C-terminally PEGylated SAKs, where the one with amyl linker and 20 kDa PEG showed the highest increase extent (27%) in the Bioactivity. Thus, our study can advance the development of long-acting pharmaceutical protein with high Bioactivity. (C) 2014 Elsevier Ltd. All rights reserved.
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preparation characterization and in vitro Bioactivity of n terminally pegylated staphylokinase dimers
Process Biochemistry, 2012Co-Authors: Dongxia Li, Jun Wang, Guifeng Zhang, Zhiguo Su, Tao HuAbstract:PEGylation can improve the therapeutic efficacy of proteins by increasing serum half-life of proteins and reducing immunogenicity and antigenicity. However, PEGylation results in a substantial loss of the Bioactivity of proteins due to the steric hindrance of polyethylene glycol (PEG). Dimerization of the proteins is an efficient approach to increase the Bioactivity of the PEG-protein conjugates. Here, staphylokinase (SAK) was used due to its therapeutic potential for coronary thrombolysis. SAK dimers (dSAK) were prepared by engineering cysteine residue at the C-terminus of SAK and dimerization of the cysteine residue with 1,4-bismaleimidobutane. PEG aldehyde was used for site-specific PEGylation of dSAK at one of its two N-termini. Structural analysis indicated that dimerization of SAK can decrease the steric hindrance of PEG and increase the binding affinity of PEG-SAK to plasminogen. Dimerization of SAK increased the relative Bioactivity of PEG-SAK from 39.0% to 62.0%. Therefore, site-specifically PEGylated dSAK at one of its two N-termini has higher Bioactivity than the N-terminal PEGylated SAK. (C) 2011 Elsevier Ltd. All rights reserved.
Bernhard Schaaf - One of the best experts on this subject based on the ideXlab platform.
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tumor necrosis factor α 308 promoter gene polymorphism and increased tumor necrosis factor serum Bioactivity in farmer s lung patients
American Journal of Respiratory and Critical Care Medicine, 2001Co-Authors: Bernhard Schaaf, Ulrike Seitzer, Vera Pravica, Sven P Aries, P ZabelAbstract:Hypersensitivity pneumonitis (HP) represents an immunologic reaction of the pulmonary parenchyma to an inhaled agent. Since tumor necrosis factor (TNF)- α is thought to be involved in the pathogenesis of HP, and polymorphisms in the TNF genes have been associated with variations in the production of TNF- α , we investigated the serum Bioactivity and genotype of TNF in HP. TNF Bioactivity was measured after hay dust challenge in eight patients with farmer's lung (Group A) and in 12 healthy, sensitized (antibody-positive) controls (Group B). Genotyping for the − 308 TNF- α promoter polymorphism and the TNF- β intron 1 gene polymorphism was performed in 20 patients with farmer's lung, 25 patients with pigeon breeder's lung, and 216 controls. TNF Bioactivity increased in Group A at 4 to 10 h after hay dust challenge, but not in Group B (p < 0.05). The frequency for the TNFA2 allele, a genotype associated with high TNF- α production in vitro, was significantly higher in farmer's lung patients (frequency [f] = ...
Ping Xiao - One of the best experts on this subject based on the ideXlab platform.
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roles of strontium and hierarchy structure on the in vitro biological response and drug release mechanism of the strontium substituted bioactive glass microspheres
Materials Science and Engineering: C, 2020Co-Authors: Wei Hong, Qihui Zhang, Linyu Song, Xiaofeng Zhao, Ping XiaoAbstract:Abstract The strontium (Sr) substituted bioactive glasses (BGs) have inimitable advantages for bone generation, but the influences of Sr substitution on Bioactivity and biocompatibility are still in debate. A brand novel porous microstructure of Sr-substituted BG microspheres was prepared by an electro-spraying technique combined with phase inversion, in which in vitro biological response (Bioactivity, cell viability, alkaline phosphatase (ALP) activity and extracellular matrix (ECM) mineralization) and drug release were clarified in view of physical chemistry and ionic release behavior. The electro sprayed bioactive glass (ESBG) microspheres involved three characteristic pores: 1000 nm. The Sr substitution on molar basis hindered the Bioactivity of the samples in some extent but the cell behavior of the MC3T3-E1 cells was not significantly discouraged. The drug release profile was also controlled by amount of Sr substitution. However, the porous structure of the microspheres conferred improvement in Bioactivity and provided a distinct three-stage drug release mode. Therefore, the Sr substituted ESBG microspheres may provide an effective way to deliver a steady supply of therapeutic ions and drugs in bone implantation patients.
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a hierarchically porous bioactive glass ceramic microsphere with enhanced Bioactivity for bone tissue engineering
Ceramics International, 2019Co-Authors: Wei Hong, Xiaofeng Zhao, Li Hu, Xin Wang, Chen Xing, Ping XiaoAbstract:Abstract A hierarchically porous bioactive glass-ceramic microsphere with enhanced Bioactivity and good biocompatibility was fabricated via electro spraying technique assisted with non-solvent induced phase inversion. The electro sprayed bioactive glass (ESBG) microspheres were 20 ± 5 μm in diameter, and composed of four characteristic pores: 1000 nm. The influences of sintering temperatures (600 °C-1000 °C) on the microstructure, crystalline phase and the related in vitro Bioactivity of the samples were investigated. All the ESBG microspheres possessed Bioactivity, and the earliest apatite deposition time (3 h) occurred in the samples sintered at 1000 °C owing to the highly porous structure and the formation of wollastonite. The in vitro cytotoxicity was evaluated via CCK-8 assay using MC3T3-E1 cells, revealing the good biocompatibility as well. These results suggest that the ESBG microsphere is a promising material for bone tissue engineering.
Shane A. Snyder - One of the best experts on this subject based on the ideXlab platform.
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in vitro bioassays to evaluate complex chemical mixtures in recycled water
Water Research, 2015Co-Authors: Bingfeng Dong, Erin M Snyder, Erik Prochazka, Frederic D.l. Leusch, Shane A. Snyder, Beate I Escher, Janet Y M TangAbstract:With burgeoning population and diminishing availability of freshwater resources, the world continues to expand the use of alternative water resources for drinking, and the quality of these sources has been a great concern for the public as well as public health professionals. In vitro bioassays are increasingly being used to enable rapid, relatively inexpensive toxicity screening that can be used in conjunction with analytical chemistry data to evaluate water quality and the effectiveness of water treatment. In this study, a comprehensive bioassay battery consisting of 36 bioassays covering 18 biological endpoints was applied to screen the Bioactivity of waters of varying qualities with parallel treatments. Samples include wastewater effluent, ultraviolet light (UV) and/or ozone advanced oxidation processed (AOP) recycled water, and infiltrated recycled groundwater. Based on assay sensitivity and detection frequency in the samples, several endpoints were highlighted in the battery, including assays for genotoxicity, mutagenicity, estrogenic activity, glucocorticoid activity, arylhydrocarbon receptor activity, oxidative stress response, and cytotoxicity. Attenuation of Bioactivity was found to be dependent on the treatment process and bioassay endpoint. For instance, ozone technology significantly removed oxidative stress activity, while UV based technologies were most efficient for the attenuation of glucocorticoid activity. Chlorination partially attenuated genotoxicity and greatly decreased herbicidal activity, while groundwater infiltration efficiently attenuated most of the evaluated Bioactivity with the exception of genotoxicity. In some cases, Bioactivity (e.g., mutagenicity, genotoxicity, and arylhydrocarbon receptor) increased following water treatment, indicating that transformation products of water treatment may be a concern. Furthermore, several types of bioassays with the same endpoint were compared in this study, which could help guide the selection of optimized methods in future studies. Overall, this research indicates that a battery of bioassays can be used to support decision-making on the application of advanced water treatment processes for removal of Bioactivity.
