Development of biosensors highly responsive to N-acetylneuraminic acid in Bacillus subtilis / 生物工程学报

Bacillus subtilis is recognized as a generally-regarded-as-safe strain, and has been widely used in the biosynthesis of high value-added products, including N-acetylneuraminic acid (NeuAc) which is widely used as a nutraceutical and a pharmaceutical intermediate. Biosensors responding to target products are widely used in dynamic regulation and high-throughput screening in metabolic engineering to improve the efficiency of biosynthesis. However, B. subtilis lacks biosensors that can efficiently respond to NeuAc. This study first tested and optimized the transport capacity of NeuAc transporters, and obtained a series of strains with different transport capacities for testing NeuAc-responsive biosensors. Subsequently, the binding site sequence of Bbr_NanR responding to NeuAc was inserted into different sites of the constitutive promoter of B. subtilis, and active hybrid promoters were obtained. Next, by introducing and optimizing the expression of Bbr_NanR in B. subtilis with NeuAc transport capacity, we obtained an NeuAc-responsive biosensor with wide dynamic range and higher activation fold. Among them, P535-N2 can sensitively respond to changes in intracellular NeuAc concentration, with the largest dynamic range (180-20 245) AU/OD. P566-N2 shows a 122-fold of activation, which is 2 times of the reported NeuAc-responsive biosensor in B. subtilis. The NeuAc-responsive biosensor developed in this study can be used to screen enzyme mutants and B. subtilis strains with high NeuAc production efficiency, providing an efficient and sensitive analysis and regulation tool for biosynthesis of NeuAc in B. subtilis.

Sex difference in brain structures of hippocampus and parahippocampus among patients with bipolar type I disorder / 中国神经精神疾病杂志

Objective This study aims to investigate the sex difference in the hippocampus and parahippocampus in patients with bipolar disorder. Methods We acquired T1－weighted structural MRI from 133 bipolar type I patients (60 males) and 144 normal controls (81 males). The General Linear Model was used to examine the relationship between sex and brain volumes of the hippocampus and parahippocampus, with age and intracranial volume as covariates. Results Patients showed significantly smaller volumes of the bilateral hippocampus and parahippocampus (P＜0.01). There were sex－by－diagnosis interactions in the left parahippocampus gyrus (F=6.534, P=0.044). Male patients had significant smaller volumes of the left parahippocampus gyrus compared to the male normal controls (P＜0.001) whereas the volumes were not significantly different between female patients and female normal controls (P＞0.05). Conclusion The results suggest sex difference in the left parahippocampus gyrus volume in patients with bipolar type I disorder, which deserves further investigation in the future bipolar imaging researches.

Influence of different surface treatments on color of chairside porcelain veneer made of CEREC Blocs / 中国组织工程研究

BACKGROUND:It is convenient to fabricate porcelain veeners using chairside computer aided design/computer aided manufacture (CAD/CAM) system. However, the color of the restorations is not ideal when the veener is cemented immediately, so different surface treatments are needed. OBJECTIVE:To investigate the influence of different surface treatments on the color of chairside porcelain veneers made of CEREC Blocs and the color match between the porcelain veneers and teeth. METHODS:Five fresh extracted maxillary central incisors were selected and prepared. Twenty-five 0.6 mm porcelain veneer specimens were fabricated with Sirona CEREC Blocs by chairside CAD/CAM system, and then randomized into five groups. Untreated specimens served as control group. The other four groups were treated respectively by polishing, glazing, glazing after polishing or staining. The color parameters of specimens and the teeth were measured with ShadeEye NCC on the middle 1/3 region of labial surfaces, and color differences (ΔE) between the specimens and teeth were calculated. Data were analyzed by SPSS 19.0 software. RESULTS AND CONCLUSION:Compared with the control group, the L* value of the glazing, glazing after polishing and staining groups were significantly decreased (P0.05). Compared with the control group, the ΔE values of glazing, glazing after polishing and staining groups were significantly decreased (P0.05). These results suggest that the chairside porcelain veneers made of CEREC Blocs can obtain satisfactory aesthetic appearance by glazing and staining.

Efficacy and safety of bevacizumab combined with chemotherapy for patients with advanced gastric cancer: A Meta-analysis / 肿瘤

Objective: The aim of this study was to evaluate the efficacy and safety of bevacizumab combined with chemotherapy for patients with advanced gastric cancer. Methods: Two researchers searched PubMed, Embase, Cochrane Library, Chinese Journal Full-text Database, VIP Chinese Science & Technology Journal Database and Wanfang database, and collected domestic and abroad published research literature about bevacizumab combined with chemotherapy in treatment of advanced gastric cancer. Two reviewers independently screened studies according to the inclusion and exclusion criteria, extracted data and assessed quality of the included studies. Then Meta-analysis was conducted using RevMan 5.3 software. Results: Five randomized control trials involving 1 202 patients were included. The Meta-analysis showed that there were statistical significances between bevacizumab combined with chemotherapy group and chemotherapy alone group in complete remission [odds ratio (OR) = 2.17, 95% confidence interval (CI)+1.07-4.38, P = 0.03], partial remission (OR = 1.53, 95% CI: 1.19-1.97, P = 0.001) and response rate (OR = 2.03, 95% CI: 1.25-3.28, P = 0.004). While there was no statistical difference in one-year survival rate (OR = 1.25, 95% CI: 0.99-1.58, P = 0.06). In terms of adverse reactions, there were statistical significances between bevacizumab combined with chemotherapy group and chemotherapy alone group in the incidence of hypertension (OR = 7.29, 95% CI: 2.71-19.64, P < 0.000 1), and toxicities were not significantly different between two groups for myelosuppression, gastrointestinal reactions, impaired liver function and arterio-venous thromboembolism. Conclusion: Bevacizumab combined with chemotherapy in the treatment of patients with advanced gastric cancer can improve the response rate, but the scheme may increase the incidence of hypertension.

Bonding properties of four different cements to glass fiber posts after different treatments / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of four different cements on the bonding effectiveness of root canal dentine and fiber post before and after different treatments.</p><p><b>METHODS</b>A total of 216 freshly extracted sound single-root-canal mandibular premolars were randomly divided into four groups. After root canal treatment and post space preparation being conducted on the premolars, Fuji I, Fuji Cem, RelyX Unicem, RelyX ARC were used respectively to bond fiber posts and were marked with group A, B, C, and D. Microleakage, micromorphology of the bonded interfaces, and pull-out bond strength were evaluated in the immediate group, thermocycling group and thermomechanical loading group.</p><p><b>RESULTS</b>In the immediate group, samples in group D showed the highest bond strength [(278 ± 26)N], followed by group C[ (219 ± 12) N], B[ (104 ± 23) N] and A[(73 ± 8) N]. Significant differences were found among all groups (P < 0.05) . A significant increase in bond strength was found in group A and B, whereas a decrease tendency was detected in group C and D after different treatments.Scanning electron microscope indicated that some little gaps were observed in group D after treatment, while a more intense bonding interface was found in group A and B. Microleakage scores in group A and B were lower than those in group C and D after aging treatments.</p><p><b>CONCLUSIONS</b>Resin cement can achieve a better immediate bond strength, while resin-modified resin cement may acquire a better long-term retention.</p>