Directed Evolution and Mutagenesis of Lysine Decarboxylase from Hafnia alvei AS1.1009 to Improve Its Activity toward Efficient Cadaverine Production

Chen Wang,Kai Zhang,Chen Zhongjun,Heng Cai,Wan Honggui,Ping-Kai Ouyang 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.3

Lysine decarboxylase (LDC) exhibits a significant role in cadaverine (1,5-pentanediamine, diaminopentane) production from lysine. In this study, an error-prone PCR and DNA shuffling were performed to improve the activity of LDC from Hafnia alvei AS1.1009 for cadaverine production. A sensitive high-throughput screening strategy based on a pH indicator was established for directed evolution of LDC. Several improved mutants were obtained from directed evolution and LDCV147F/E583G mutant showed highest activity to catalyze lysine to cadaverine. This mutant showed 1.62-fold high LDC activity when compared to wild-type. Further analysis by site-directed mutagenesis reveled that only the mutant E583G was sufficient for higher catalytic activity. Wild type LDC and mutant LDCE583G were purified by an improved method including hydrophobic chromatography. These purified enzymes were characterized and the kinetic parameters were compared between LDCE583G and WT LDC. Vmax of LDCE583G was 1.32-fold higher than that of WT LDC. Use of LDCE583G mutant showed 1.48-fold improved productivity of cadaverine when compared to wild type. The concentration of cadaverine in E. coli JM109/pTrc99a-ldc2-41 was 63.9 g/L with conversion yield of 93.4% during 5 h. These results indicate that the mutation has positive effects on improving LDC activity and a potential candidate for cadaverine production.

Cerebrospinal Fluid Leakage after Surgeries on the Thoracic Spine: A Review of 362 Cases

Panpan Hu,Miao Yu,Xiaoguang Liu,Zhongjun Liu,Liang Jiang, Feng Wei,Zhongqiang Chen 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.3

Study Design: A retrospective clinical review. Purpose: To describe the incidence of cerebrospinal fluid leakage (CSFL) after thoracic decompression and examine the CSFL predisposing clinical factors. Overview of Literature: CSFL is a common complication following thoracic decompression but has not been sufficiently addressed in former studies. Methods: A cohort of 362 cases of thoracic decompression from February of 2005 to June of 2013 was examined. The case medical records were reviewed and the occurrence of CSFL and the related clinical parameters were noted. The incidence of CSFL for the entire cohort and each surgical approach were described. Besides, the relationship between CSFL and other clinical parameters were assessed, of which odds ratio values of all CSFL-associated parameters were calculated using multivariate logistic regression analysis. Results: The incidence of CSFL for the entire cohort was 32.3%. Different surgical approaches had different incidences of CSFL, and circumferential decompression had the highest incidence. Though many different clinical parameters were related to the occurrences of CSFL, being older than 52 years, having ossification of the posterior longitudinal ligament or having longer operative segments than 3 vertebrae were significant risk factors for CSFL (p <0.05). Besides, surgeries on the mid-thoracic spine had an increased risk of CSFL (p <0.05). Conclusions: From our analysis, CSFL was a common complication after thoracic decompression with the incidence of up to 32.3%. This study identified the predisposing clinical factors, and spinal surgeons should be aware of these risk factors to reduce its incidence.

Polymicrobial and Monomicrobial Infections after Spinal Surgery: A Retrospective Study to Determine which Infection is more Severe

Shaoqiang Liu,Qiang Qi,Zhongqiang Chen,Ning Liu,Zhaoqing Guo,Chuiguo Sun,Weishi Li,Yan Zeng,Zhongjun Liu 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.3

Study Design: A retrospective clinical review. Purpose: To investigate the difference in clinical manifestations and severity between polymicrobial and monomicrobial infections after spinal surgery. Overview of Literature: Surgical site infections (SSIs) after spinal surgery are a major diagnostic and therapeutic challenge for spinal surgeons. Polymicrobial infections after spinal surgery seem to result in poorer outcomes than monomicrobial infections because of complementary resistance to antibiotics. However, comparison of the clinical manifestations and severity between polymicrobial and monomicrobial infections are limited. Methods: Sixty-seven patients with SSIs after spinal surgery were studied: 20 patients with polymicrobial infections and 47 with monomicrobial infections. Pathogenic bacteria identified were counted and classified. Age, sex, and body mass index were compared between the two groups to identify homogeneity. The groups were compared for clinical manifestations by surgical site, postoperative time to infection, infection site, incisional drainage, incisional swelling, incisional pain, neurological signs, temperature, white blood cell count, and the percentage of neutrophils. Finally, the groups were compared for severity by hospital stay, number of rehospitalizations, number of debridements, duration of antibiotics administration, number of antibiotics administered, and implant removal. Results: Polymicrobial infections comprised 29.9% of SSIs after spinal surgery, and most polymicrobial infections (70.0%) were caused by two species of bacteria only. There was no difference between the groups in terms of clinical manifestations and severity. In total, 96 bacterial strains were isolated from the spinal wounds: 60 strains were gram-positive and 36 were gram-negative pathogenic bacteria. Staphylococcus aureus , Staphylococcus epidermidis , Escherichia coli , and Enterobacter cloacae were cultured in order of the frequency of appearance. Conclusions: Most polymicrobial infections were caused by two bacterial species after spinal surgery. There was no difference in clinical manifestations or severity between polymicrobial and monomicrobial infections.

A Modified NHL-BFM-95 Regimen Produces Better Outcome Than HyperCVAD in Adult Patients with T-Lymphoblastic Lymphoma, a Two-Institution Experience

Chun Li,Zhi-Jun Wuxiao,Xiaoqin Chen,Guanjun Chen,Yue Lu,Zhongjun Xia,Yang Liang,Hua Wang 대한암학회 2020 Cancer Research and Treatment Vol.52 No.2

Purpose Lymphoblastic lymphoma (LBL) is an invasive neoplasm of precursor T-cell or B-cell lineage. A broadly accepted standard treatment for adult LBL has not yet been defined. Materials and Methods To address this issue, we compared two chemotherapy regimens: a modified non-Hodgkin lymphoma Berlin–Frankfurt–Mu!nster-95 (NHL-BFM-95) regimen and HyperCVAD/MA. This retrospective study consecutively enrolled 207 adult LBL patients at two hospitals from 2000 to 2018. Univariate and multivariate analysis were used to assess prognostic factors. Results In the present study, most clinical characteristics were similar between the two treatment groups except for age and lactate dehydrogenase (LDH) level. Patients treated with modified NHL-BFM-95 regimen tended to be younger and with elevated LDH level. The modified NHLBFM- 95 regimen produced better treatment outcomes than those with HyperCVAD/MA in patients with T-LBL or patients < 40 years. Treatment with HyperCVAD/MA, high Eastern Cooperative Oncology Group scores, and bone marrow involvement were independent risk factors in T-LBL. No patients interrupted treatment for severe adverse events. Conclusion The results suggested that the modified regimen is well-tolerated and can produce the promising outcomes in patients with T-LBL or patients < 40 years.

Analysis of Global Sagittal Postural Patterns in Asymptomatic Chinese Adults

Panpan Hu,Miao Yu,Zhuoran Sun,Weishi Li,Liang Jiang,Feng Wei,Xiaoguang Liu,Zhongqiang Chen,Zhongjun Liu 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.2

Study Design: A prospective imaging study. Purpose: To characterize the distribution of the global sagittal postural patterns in asymptomatic Chinese adults using Roussouly classification. Overview of Literature: The norms of sagittal parameters in asymptomatic Chinese population have been previously described, but no report described their global sagittal postural patterns as characterized by Roussouly classification. Methods: A cohort of 272 asymptomatic Chinese adults was recruited. Data was assimilated by reviewing the films for each subject. Sagittal parameters were measured and sagittal postural patterns were then determined according to Roussouly classification. The pattern distributions were compared across genders within the study cohort. We also compared the data across different ethnicities from our study and a previous study to further characterize Chinese sagittal postures. Results: The cohort included 161 males and 111 females, with mean age of 23.2±4.4 years. The average descriptive results were as below: pelvic incidence (PI) 46.4°±9.6°, thoracic kyphosis (TK) 24.2°±9.0°, lumbar lordosis (LL) 50.6°±10.6°, sacral slope (SS) 37.2°±7.6°, pelvic tilt (PT) 9.4°±6.8°, spinosacral angle (SSA) 131.1°±7.5° and sagittal vertical axis (SVA) 17.24±32.36 mm. Despite a significant difference between two genders in LL, PI, SSA, and SVA, no difference was found in the distribution of Roussouly types among them. 47.8% of our cohort belonged to Roussouly type 3, while type 1, 2 and 4 comprised 23.2%, 14.0% and 15.1% of the subjects, respectively. Roussouly classification was capable of categorizing sagittal parameters except for the PT. This study also found that 4.4% of the recruited subjects belonged to the C7-anterior subgroup. Conclusions: From a characterization of the sagittal postural patterns of asymptomatic Chinese adults using Roussouly classification, the distribution was similar between Chinese males and females; however, from a cross-study comparison, it was different between asymptomatic Chinese and Caucasian adults, with a higher proportion of Roussouly type 3 in Chinese adults.