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Purification and Characterization of an Extracellular Protease from Bacillus pumilus CN8
Mei-Hu Ma,Yong-Guo Jin,Hao-Li Li,Jun Wang,Ha-Na Kim,오덕환 한국식품위생안전성학회 2011 한국식품위생안전성학회지 Vol.26 No.1
The protease produced by a Bacillus pumilus CN8 strain was purified by DEAE-Cellulose-52 ion exchange. It has a molecular weight of approximately 96,920 Dalton. In the present study, this protease showed strong activity over a broad range of pH (6.5-9.5) and temperature from 40℃ to 60℃, and the protease performed the maximal activity at pH 7.3 at 42℃. The effect of metal ions on protease activity showed that K+ could slightly increase the protease activity, and other ions such as Zn²+, Fe²+, Na+, Ca²+, Mg²+ had no significant activation or inhibition to the protease (P > 0.05), and the more important is that Cu²+, Mn²+, Sn²+, Cd²+ had a strong inhibitory effect on the protease activity.
Quasi-Fixed-Frequency Hysteresis Current Tracking Control Strategy for Modular Multilevel Converters
Mei, Jun,Ji, Yu,Du, Xiaozhou,Ma, Tian,Huang, Can,Hu, Qinran The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
This study proposes a quasi-fixed-frequency hysteresis current tracking control strategy for modular multilevel converters (MMCs) on the basis of voltage partition principle. First, by monitoring the grid voltage and the deviation between the output and reference currents, the output voltage is determined, thus prompting the output current to quickly and efficiently track the given current. Second, the voltages of the upper/lower capacitor of the arm and the voltages between the upper and lower arms are balanced by combining these arms with virtual loop mapping and arm voltage balance control, respectively. In particular, the proposed method is designed for any level and number of sub-modules. The validity of the proposed method is verified by simulations and experimental results of a five-level MMC prototype.
Quasi-Fixed-Frequency Hysteresis Current Tracking Control Strategy for Modular Multilevel Converters
Jun Mei,Yu Ji,Xiaozhou Du,Tian Ma,Can Huang,Qinran Hu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
This study proposes a quasi-fixed-frequency hysteresis current tracking control strategy for modular multilevel converters (MMCs) on the basis of voltage partition principle. First, by monitoring the grid voltage and the deviation between the output and reference currents, the output voltage is determined, thus prompting the output current to quickly and efficiently track the given current. Second, the voltages of the upper/lower capacitor of the arm and the voltages between the upper and lower arms are balanced by combining these arms with virtual loop mapping and arm voltage balance control, respectively. In particular, the proposed method is designed for any level and number of sub-modules. The validity of the proposed method is verified by simulations and experimental results of a five-level MMC prototype.
Identification of a Cancer Stem-like Population in the Lewis Lung Cancer Cell Line
Zhang, An-Mei,Fan, Ye,Yao, Quan,Ma, Hu,Lin, Sheng,Zhu, Cong-Hui,Wang, Xin-Xin,Liu, Jia,Zhu, Bo,Sun, Jian-Guo,Chen, Zheng-Tang Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.3
Objective: Although various human cancer stem cells (CSCs) have been defined, their applications are restricted to immunocompromised models. Developing a novel CSC model which could be used in immunocompetent or transgenic mice is essential for further understanding of the biomolecular characteristics of tumor stem cells. Therefore, in this study, we analyzed murine lung cancer cells for the presence of CSCs. Methods: Side population (SP) cells were isolated by fluorescence activated cell sorting, followed by serum-free medium (SFM) culture, using Lewis lung carcinoma cell (LLC) line. The self-renewal, differentiated progeny, chemosensitivity, and tumorigenic properties in SP and non-SP cells were investigated through in vitro culture and in vivo serial transplantation. Differential expression profiles of stem cell markers were examined by RT-PCR. Results: The SP cell fraction comprised 1.1% of the total LLC population. SP cells were available to grow in SFM, and had significantly enhanced capacity for cell proliferation and colony formation. They were also more resistant to cisplatin in comparison to non-SP cells, and displayed increased tumorigenic ability. Moreover, SP cells showed higher mRNA expression of Oct-4, ABCG2, and CD44. Conclusion: We identified SP cells from a murine lung carcinoma, which possess well-known characteristics of CSCs. Our study established a useful model that should allow investigation of the biological features and pharmacosensitivity of lung CSCs, both in vitro and in syngeneic immunocompetent or transgenic/knockout mice.
Xu, Jia-Li,Hu, Ling-Min,Huang, Ming-De,Zhao, Wan,Yin, Yong-Mei,Hu, Zhi-Bin,Ma, Hong-Xia,Shen, Hong-Bing,Shu, Yong-Qian Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.3
Objective: NBS1 plays a key role in the repair of DNA double-strand break (DSB). We conducted this study to investigate the effect of two critical polymorphisms (rs1805794 and rs13312840) in NBS1 on treatment response and prognosis of advanced non-small cell lung cancer (NSCLC) patients with platinum-based chemotherapy. Methods: Using TaqMan methods, we genotyped the two polymorphisms in 147 NSCLC patients. Odds ratios (ORs) and their 95% confidential intervals (CIs) were calculated as a measure of difference in the response rate of platinum-based chemotherapy using logistic regression analysis. The Kaplan-Meier and log-rank tests were used to assess the differences in progression-free survival (PFS) and overall survival (OS). Cox proportional hazards model was applied to assess the hazard ratios (HRs) for PFS and OS. Results: Neither of the two polymorphisms was significantly associated with treatment response of platinum-based chemotherapy. However, patients carrying the rs1805794 CC variant genotype had a significantly improved PFS compared to those with GG genotype (16.0 vs. 8.0 months, P = 0.040). Multivariable cox regression analysis further showed that rs1805974 was a significantly favorable prognostic factor for PFS [CC/CG vs. GG: Adjusted HR = 0.62, 95% CI: 0.39-0.99; CC vs. CG/GG: Adjusted HR = 0.56, 95% CI: 0.32-0.97). Similarly, rs13312840 with a small sample size also showed a significant association with PFS (CC vs. CT/TT: Adjusted HR = 25.62, 95% CI: 1.53-428.39). Conclusions: Our findings suggest that NBS1 polymorphisms may be genetic biomarkers for NSCLC prognosis especially PFS with platinum-based chemotherapy in the Chinese population.
Yao, Quan,Sun, Jian-Guo,Ma, Hu,Zhang, An-Mei,Lin, Sheng,Zhu, Cong-Hui,Zhang, Tao,Chen, Zheng-Tang Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1
Lung cancer is the most common causes of cancer-related deaths worldwide, and a lack of effective methods for early diagnosis has greatly impacted the prognosis and survival rates of the affected patients. Tumor-initiating cells (TICs) are considered to be largely responsible for tumor genesis, resistance to tumor therapy, metastasis, and recurrence. In addition to representing a good potential treatment target, TICs can provide clues for the early diagnosis of cancer. MicroRNA (miRNA) alterations are known to be involved in the initiation and progression of human cancer, and the detection of related miRNAs in TICs is an important strategy for lung cancer early diagnosis. As Hsa-miR-155 (miR-155) can be used as a diagnostic marker for non-small cell lung cancer (NSCLC), a smart molecular beacon of miR-155 was designed to image the expression of miR-155 in NSCLC cases. TICs expressing CD133 and CD338 were obtained from A549 cells by applying an immune magnetic bead isolation system, and miR-155 was detected using laser-scanning confocal microscopy. We found that intracellular miR-155 could be successfully detected using smart miR-155 molecular beacons. Expression was higher in TICs than in A549 cells, indicating that miR-155 may play an important role in regulating bio-behavior of TICs. As a non-invasive approach, molecular beacons could be implemented with molecular imaging to diagnose lung cancer at early stages.
Xiang Xu,Yu-Nan Lu,Jia-Hui Cheng,Hui-Wen Lan,Jing-Mei Lu,Guang-Nan Jin,Guang-Hua Xu,Cheng-Hua Jin,Juan Ma,Hu-Nan Piao,Xuejun Jin,Lian-Xun Piao 고려인삼학회 2022 Journal of Ginseng Research Vol.46 No.1
Background: Maternal Toxoplasma gondii (T. gondii) infection during pregnancy has been associated with various mental illnesses in the offspring. Ginsenoside Rh2 (GRh2) is a major bioactive compound obtained from ginseng that has an anti-T. gondii effect and attenuates microglial activation through toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-kB) signaling pathway. GRh2 also alleviated tumor-associated or lipopolysaccharide-induced depression. However, the effects and potential mechanisms of GRh2 on depression-like behavior in mouse offspring caused by maternal T. gondii infection during pregnancy have not been investigated. Methods: We examined GRh2 effects on the depression-like behavior in mouse offspring, caused by maternal T. gondii infection during pregnancy, by measuring depression-like behaviors and assaying parameters at the neuronal and molecular level. Results: We showed that GRh2 significantly improved behavioral measures: sucrose consumption, forced swim time and tail suspended immobility time of their offspring. These corresponded with increased tissue concentrations of 5-hydroxytryptamine and dopamine, and attenuated indoleamine 2,3-dioxygenase or enhanced tyrosine hydroxylase expression in the prefrontal cortex. GRh2 ameliorated neuronal damage in the prefrontal cortex. Molecular docking results revealed that GRh2 binds strongly to both TLR4 and high mobility group box 1 (HMGB1). Conclusion: This study demonstrated that GRh2 ameliorated the depression-like behavior in mouse offspring of maternal T. gondii infection during pregnancy by attenuating the excessive activation of microglia and neuroinflammation through the HMGB1/TLR4/NF-kB signaling pathway. It suggests that GRh2 could be considered a potential therapy in preventing and treating psychiatric disorders in the offspring mice of mothers with prenatal exposure to T. gondii infection.
An Efficient Method for Co-purification of Eggshell Matrix Proteins OC-17, OC-116, and OCX-36
Maojie Zhang,Ning Wang,Qi Xu,Putri Widyanti Harlina,Mei-hu Ma 한국축산식품학회 2016 한국축산식품학회지 Vol.36 No.6
In this study, we improved the eggshell-membrane separation process by separating the shell and membrane with EDTA solution, evaluating effects of three different extraction solutions (acetic acid, EDTA, and phosphate solution), and co-purifying multiple eggshell proteins with two successive ion-exchange chromatography procedures (CM Sepharose Fast Flow and DEAE Sepharose Fast Flow). The recovery and residual rates of eggshell and membrane separated by the modified method with added EDTA solution were 93.88%, 91.15% and 1.01%, 2.87%, respectively. Ovocleidin-116 (OC-116) and ovocalyxin-36 (OCX-36) were obtained by loading 50 mM Na-Hepes, pH 7.5, 2 mM DTT and 350 mM NaCl buffer onto the DEAE-FF column at a flow rate of 1 mL/min, ovocleidin-17 (OC-17) was obtained by loading 100 mM NaCl, 50 mM Tris, pH 8.0 on the CM-FF column at a flow rate of 0.5 mL/min. The purities of OCX-36, OC-17 and OC-116 were 96.82%, 80.15% and 73.22%, and the recovery rates were 55.27%, 53.38% and 36.34%, respectively. Antibacterial activity test suggested that phosphate solution extract exhibited significantly higher activity against the tested bacterial strains than the acetic acid or EDTA extract, probably due to more types of proteins in the extract. These results demonstrate that this separation method is feasible and efficient.
Qun Huang,Shu-gang Li,Hui Teng,Yong-guo Jin,Mei-hu Ma,Hong-bo Song 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6
Angiotensin-I-converting enzyme (ACE) inhibitory peptides were prepared from ovalbumin using enzyme hydrolysis with pepsin as an enzyme source. Effects of pH, enzyme dosage, substrate concentration, hydrolysis temperature, and time on the degree of hydrolysis and the ACE inhibition rate were investigated using single factor experiments. Preparation conditions for ACE inhibitory peptides were optimized using a response surface design on the base of single factor experiments. Optimum preparation conditions were a substrate concentration of 5.2 g/100 mL of D.W with a pH value of 2.5, an enzyme dosage of 14,000 U/g, and a hydrolysis time of 250 min at 30℃. The ACE inhibition rate was up to 70.55±1.13% under these conditions.