Expression and Efficient Purification of Tag-cleaved Active Recombinant Human Insulin-like Growth Factor-II from Escherichia coli

Hongbo Li,Xiaoyan Hui,Peng Li,Aimin Xu,Shiwu Li,Shouguang Jin,Donghai Wu 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.2

Insulin-like growth factor-II (IGF2) is a growth factor for the control of cell proliferation and apoptosis. To explore the clinical use of human IGF2, an efficient method for production of a large amount of active recombinant hIGF2 is necessary. Human IGF2 cDNA was cloned into pET32 vector where it is under the control of an IPTGinducible T7 promoter. High level soluble thioredoxin (Trx)- hIGF2 fusion protein was produced at room temperature following IPTG induction, amounting up to 20% of the total soluble bacterial proteins. The recombinant TrxhIGF2 fusion protein was purified to an approximate 95% purity using Ni+-NTA affinity chromatography with an overall yield of 120 mg protein per liter of bacterial culture. After cleavage of the Trx fusion fragment by recombinant enterokinase, the tag-free recombinant hIGF2 protein (rhIGF2) was purified by passage through the Ni+-NTA affinity column again. Biological activity of the purified hIGF2 was determined by its ability to support NIH/3T3 cells proliferation and to activate AKT signaling pathways. Our results demonstrate that tag-free active rhIGF2 can easily be obtained for various applications from E. coli using the procedure described in this report.

DC-Link Active Power Filter for High-Power Single-Phase PWM Converters

Hongbo Li,Kai Zhang,Hui Zhao 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3

Single phase converters suffer from ripple power pulsating at twice the line frequency. The ripple power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, resulting in a low power density and a high cost. An alternative solution is using a dc link active power filter (APF) to direct the pulsating power into another energy-storage component. The main dc link filter capacitor can then be reduced substantially. Based on a mainstream dc APF topology, this paper proposed a new control strategy incorporating both dual-loop control and repetitive control. The circuit parameter design is also re-examined from a control point of view. The proposed APF scheme has better control performance, and is more suited for high power applications since it works in CCM and with a low switching frequency.

Experimental study on ultrasonic-assisted grinding of micro-structured surface on silicon carbide using small diameter grinding wheel

Hongbo Li,Tao Chen,Zhenyan Duan,Yiwen Zhang,Haotian Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

As an effective machining method for hard and brittle materials, ultrasonicassisted grinding (UAG) was employed to manufacture microstructures on SiC in this study. The kinematic characteristics of abrasive grains during machining were analyzed first. After that, the influence of machining parameters on the shape accuracy and surface quality was revealed experimentally. The results demonstrate that the feed rate and ultrasonic amplitude have significant effects on machining quality. The introduction of ultrasonic vibration can effectively reduce the grinding force and improve the surface finish quality. For the micro cylinder array, by selecting the ultrasonic amplitude rationally, the peak-to-valley (PV) value and surface roughness can be decreased by 15.8 % and 27.5 %. Furthermore, microcracks, dominated by lateral cracks and fractures were found on the sub-surface. Compared with conventional grinding, UAG can reduce the subsurface damage (SSD) depth and gain a more uniform distribution of damage regions along the machined surface.

Acute and repeated dose 26-week oral toxicity study of 20(S)-ginsenoside Rg3 in Kunming mice and Sprague-Dawley rats

Li, Chunmei,Wang, Zhezhe,Li, Guisheng,Wang, Zhenhua,Yang, Jianrong,Li, Yanshen,Wang, Hongtao,Jin, Haizhu,Qiao, Junhua,Wang, Hongbo,Tian, Jingwei,Lee, Albert W.,Gao, Yonglin The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.2

Background: 20(S)-ginsenoside-Rg3 (C₄₂H₇₂O₁₃), a natural triterpenoid saponin, is extracted from red ginseng. The increasing use of 20(S)-ginsenoside Rg3 has raised product safety concerns. Methods: In acute toxicity, 20(S)-ginsenoside Rg3 was singly and orally administrated to Kunming mice and Sprague-Dawley (SD) rats at the maximum doses of 1600 mg/kg and 800 mg/kg, respectively. In the 26-week toxicity study, we used repeated oral administration of 20(S)-ginsenoside Rg3 in SD rats over 26 weeks at doses of 0, 20, 60, or 180 mg/kg. Moreover, a 4-week recovery period was scheduled to observe the persistence, delayed occurrence, and reversibility of toxic effects. Results: The result of acute toxicity shows that oral administration of 20(S)-ginsenoside Rg3 to mice and rats did not induce mortality or toxicity up to 1600 and 800 mg/kg, respectively. During a 26-week administration period and a 4-week withdrawal period (recovery period), there were no significant differences in clinical signs, body weight, food consumption, urinalysis parameters, biochemical and hematological values, or histopathological findings. Conclusion: The mean oral lethal dose (LD₅₀) of 20(S)-ginsenoside Rg3, in acute toxicity, is above 1600 mg/kg and 800 mg/kg in mice and rats, respectively. In a repeated-dose 26-week oral toxicity study, the no-observed-adverse-effect level for female and male SD rats was 180 mg/kg.

Intelligent Scheduling Control of Networked Control Systems with Networked-induced Delay and Packet Dropout

Hongbo Li,Zengqi Sun,Badong Chen,Huaping Liu,Fuchun Sun 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.6

Networked control systems (NCSs) have gained increasing attention in recent years due to their advantages and potential applications. The network Quality-of-Service (QoS) in NCSs always fluctuates due to changes of the traffic load and available network resources. To handle the network QoS variations problem, this paper presents an intelligent scheduling control method for NCSs, where the sampling period and the control parameters are simultaneously scheduled to compensate the effect of QoS variation on NCSs performance. For NCSs with network-induced delays and packet dropouts, a discrete-time switch model is proposed. By defining a sampling-period-dependent Lyapunov function and a common quadratic Lyapunov function, the stability conditions are derived for NCSs in terms of linear matrix inequalities (LMIs). Based on the obtained stability conditions, the corresponding controller design problem is solved and the performance optimization problem is also investigated. Simulation results are given to demonstrate the effectiveness of the proposed approaches.

Study on Axial Compression Behavior of Cross-Shaped and L-Shaped Multi-cavity Concrete-Filled Steel Tube Special Shaped Column

Hongbo Li,Yufei Tong,Jianguang Yin,Hubiao Zhang,Changyu Yan 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

Multi-cavity concrete-fi lled steel tube special shaped column (CFSTSSC) combines the excellent characteristics of multicavity steel tube and core concrete. CFSTSSC has the advantages of high bearing capacity, good ductility, and strong energy dissipation capacity. At present, accurate calculation methods for these kinds of structures are limited and research into crossshaped and L-shaped multi-cavity CFSTSSCs is not available. Therefore, the axial compression behavior of cross-shaped and L-shaped multi-cavity CFSTSSCs has been investigated, though experimental research and numerical simulation, in this study. First, axial compression tests were carried out on three cross-shaped and three L-shaped multi-cavity CFSTSSCs to analyze their failure modes, axial load-strain curve, ductility index, and ultimate bearing capacity. Then, fi nite element (FE) calculation models of cross-shaped and L-shaped multi-cavity CFSTSSCs were established. The FE models are in good agreement with the experimental results, which provides a foundation for further parameter analysis and failure mechanism study of special shaped columns. Finally, combining parameter analysis and limit equilibrium theory, equations for calculating the ultimate bearing capacity of cross-shaped and L-shaped multi-cavity CFSTSSCs were proposed. The results show that the error between the simplifi ed equation and the FE result is less than 15%, indicating that the equations can provide reference for practical engineering applications.

DC-Link Active Power Filter for High-Power Single-Phase PWM Converters

Li, Hongbo,Zhang, Kai,Zhao, Hui The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.3

Single phase converters suffer from ripple power pulsating at twice the line frequency. The ripple power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, resulting in a low power density and a high cost. An alternative solution is using a dc link active power filter (APF) to direct the pulsating power into another energy-storage component. The main dc link filter capacitor can then be reduced substantially. Based on a mainstream dc APF topology, this paper proposed a new control strategy incorporating both dual-loop control and repetitive control. The circuit parameter design is also re-examined from a control point of view. The proposed APF scheme has better control performance, and is more suited for high power applications since it works in CCM and with a low switching frequency.

Trend analysis of prosthodontic treatment modality between 2005 and 2008 in Seoul National University Dental Hospital

Li, Hongbo,Lee, Jai-Bong,Liu, Hongchen,Han, Jung-Suk,Yang, Jae-Ho,Koak, Jai-Young,Heo, Seong-Joo 대한치과보철학회 2010 The Journal of Advanced Prosthodontics Vol.2 No.1

PURPOSE. The aim of this article is to analyze the preference for treatment modality of dentists. MATERIAL AND METHODS. Data of 20,038 patients was involved. Data analysis were done by distribution according to the various kinds of prosthesis, including complete denture, removable partial denture, fixed partial denture, implant-supported dental prosthesis as well as distribution according to the professional titles of the dentists finishing the treatment, including resident and professors. RESULTS. The number of cases of dental prosthesis increased year by year. 61.06% of the patients accepted fixed partial denture restoration. The number of patients who accepted implant supported restoration is also increasing year by year. The number of complete denture, implant-supported dental prosthesis finished by professors was larger than that done by residents, while it was contrary for removable partial denture, fixed partial denture, and the difference was statistically significant (P< .05). CONCLUSION. Professors and residents have some difference in the categorization of prosthesis finished. Fixed partial denture and implant-supported dental prosthesis are preferred.

Optimization of recombinant Zea mays transglutaminase production and its influence on the functional properties of yogurt

Hongbo Li,Yanhua Cui,Lanwei Zhang,Lili Zhang,Hui Liu,Jinghua Yu 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.3

The requirements for the production of optimized Zea mays transglutaminase (TGZo) using Pichia pastoris GS115 (pPIC9K-tgzo) were optimized in this study. Plackett–Burman design was used to screen variables that significantly influence TGZo production. Oleic acid, methanol, and loading volume were identified as the most significant parameters. Central composite design was employed to determine the optimal level of these three parameters for TGZo production. Results showed that 1078 mU/mL of TGZo activity and 7.6 mg/L of TGZo production were obtained under conditions of 0.07% oleic acid, 1.31% methanol, and 7.36% loading volume. To explore the functional characteristics of TGZo, it was used in yogurt. It was found that the addition of TGZo could produce yogurt with stronger acid gel and higher consistency, cohesiveness, index of viscosity, and apparent viscosity than the untreated product. Therefore, TGZo can be used as a substitute for microbial transglutaminase in the yogurt, even in the food industry.

Heterologous Expression and Purification of Zea mays Transglutaminase in Pichia pastoris

Hongbo Li,Yanhua Cui,Lanwei Zhang,Huaxi Yi,Xue Han,Yuehua Jiao,Ming Du,Rongbo Fan,Shuang Zhang 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.5

Transglutaminases (TGases) are a family ofenzymes that catalyze the cross-linking of proteins and arewidely used in the food industry to improve the texture ofdairy, meat, and bread products. Zea mays transglutaminase(TGZ) is a new type of TGase with a wide potential. TGZwas expressed in the yeast Pichia pastoris under an alcoholoxidase promoter. Maximal expression of recombinantTGZ was achieved by inducing recombinant GS115(pPIC9K-tgz) in BMMY medium using 1.5% methanol for96 h. Secreted TGZ was initially separated using Superdex200 resin and further purified on cation exchange resin. The activity of TGZ following purification was 0.32 U/mgof protein. The polymerization effect of TGZ on caseincatalyzed by recombinant TGZ was slightly lower than theeffect of microbial transglutaminase (MTG). TGZ is a newpotential additive for the food industry.