Bacillus subtilis is a non-pathogenic Gram-positive bacterium that has been widely used to produce industrially and pharmaceutically relevant proteins.Trehalose,a non reducing disaccharide used as protective agent and...Bacillus subtilis is a non-pathogenic Gram-positive bacterium that has been widely used to produce industrially and pharmaceutically relevant proteins.Trehalose,a non reducing disaccharide used as protective agent and additive in foodstuffs and pharmaceutical products,can be prepared by trehalose synthase(TreS).The present work aims to construct a robust recombinant B.subtilis to achieve the secretory expression of TreS.In this study,the treS gene from Pseudomonas putida ATCC47054 was amplified by PCR and further cloned and expressed in B.subtilis WB800 N using pHT01 as expression vector.For avoiding the use of inducer,promoter P_(srfA)was used to replace the promoter P_(grac)in pHT01 and verify the activity of recombinant trehalose synthase.The TreS activity assay was employed to evaluate the performance of recombinant B.subtilis W800 N under different phosphate concentrations,carbon sources,carbon source concentrations,nitrogen sources and pH.The results showed that the P_(srfA)promoter had a good regulation effect under pH 8.0 condition,and the enzyme activity reached 6000 U/L.Using the PhoD as the secretory signal peptide,TreS was effectively secreted,and the extracellular enzyme activity reached 2100 U/L,accounting for 35%of the total enzyme activity.By optimizing the medium and fermentation conditions,the extracellular enzyme activity reached 6900 U/L in 5 L of fermentor,and the proportion reached 48%.The pHT01-P_(srfA)-PhoD-treS secretory recombinant B.subtilis constructed in this study has great potential in trehalose synthase production.展开更多
Intrahepatic cholangiocarcinoma(iCCA)is a rare cancer with generally poor prognosis.In this narrative review,we examine the role of thermal ablation and summarize the current literature.Radiofrequency ablation(RFA)and...Intrahepatic cholangiocarcinoma(iCCA)is a rare cancer with generally poor prognosis.In this narrative review,we examine the role of thermal ablation and summarize the current literature.Radiofrequency ablation(RFA)and microwave ablation(MWA)are both safe and well-tolerated as a minimally invasive local curative treatment option for patients suffering from primary and secondary liver tumors.Both methods can be used in patients with medical morbidities that would preclude surgery,as well as individuals with anatomical or functional constraints that impede liver resection.In unresectable iCCA,the median OS after conventional percutaneous US-or CT-guided RFA and MWA is between 20 and 39 months and 10 and 28 months,respectively.In recurrent iCCA,percutaneous RFA and MWA achieved a median OS of 21-27 months and 21-31 months,respectively.These data are comparable to long-term outcomes after surgical resection(SR),with the number of nodules and tumor size affecting prognosis.Stereotactic radiofrequency ablation(SRFA)allows for effective treatment of large and multiple iCCA nodules within one session and achieves short-and long-term results in inoperable patients compared with resection.With the addition of SRFA as an alternative treatment option,the proportion of patients who can be treated with curative treatment has significantly increased.In the absence of prospective trials comparing thermal ablation and surgical resection,we recommend a patient-specific decision-making process.Future research to identify technical and clinical prognostic criteria,as well as molecular markers of tumor biology,may help select patients for ablation and subsequent outcomes.展开更多
基金Supported by the National Nature Science Foundation of China(No.31501413)Shandong key project of Research&Development plan(No.2017GSF221019)+1 种基金Young doctorate Cooperation Fund Project,Qi Lu University of Technology(Shandong Academy of Sciences)(No.2017BSHZ021)Shandong Natural Science Foundation Project(ZR2017BC072)
文摘Bacillus subtilis is a non-pathogenic Gram-positive bacterium that has been widely used to produce industrially and pharmaceutically relevant proteins.Trehalose,a non reducing disaccharide used as protective agent and additive in foodstuffs and pharmaceutical products,can be prepared by trehalose synthase(TreS).The present work aims to construct a robust recombinant B.subtilis to achieve the secretory expression of TreS.In this study,the treS gene from Pseudomonas putida ATCC47054 was amplified by PCR and further cloned and expressed in B.subtilis WB800 N using pHT01 as expression vector.For avoiding the use of inducer,promoter P_(srfA)was used to replace the promoter P_(grac)in pHT01 and verify the activity of recombinant trehalose synthase.The TreS activity assay was employed to evaluate the performance of recombinant B.subtilis W800 N under different phosphate concentrations,carbon sources,carbon source concentrations,nitrogen sources and pH.The results showed that the P_(srfA)promoter had a good regulation effect under pH 8.0 condition,and the enzyme activity reached 6000 U/L.Using the PhoD as the secretory signal peptide,TreS was effectively secreted,and the extracellular enzyme activity reached 2100 U/L,accounting for 35%of the total enzyme activity.By optimizing the medium and fermentation conditions,the extracellular enzyme activity reached 6900 U/L in 5 L of fermentor,and the proportion reached 48%.The pHT01-P_(srfA)-PhoD-treS secretory recombinant B.subtilis constructed in this study has great potential in trehalose synthase production.
文摘Intrahepatic cholangiocarcinoma(iCCA)is a rare cancer with generally poor prognosis.In this narrative review,we examine the role of thermal ablation and summarize the current literature.Radiofrequency ablation(RFA)and microwave ablation(MWA)are both safe and well-tolerated as a minimally invasive local curative treatment option for patients suffering from primary and secondary liver tumors.Both methods can be used in patients with medical morbidities that would preclude surgery,as well as individuals with anatomical or functional constraints that impede liver resection.In unresectable iCCA,the median OS after conventional percutaneous US-or CT-guided RFA and MWA is between 20 and 39 months and 10 and 28 months,respectively.In recurrent iCCA,percutaneous RFA and MWA achieved a median OS of 21-27 months and 21-31 months,respectively.These data are comparable to long-term outcomes after surgical resection(SR),with the number of nodules and tumor size affecting prognosis.Stereotactic radiofrequency ablation(SRFA)allows for effective treatment of large and multiple iCCA nodules within one session and achieves short-and long-term results in inoperable patients compared with resection.With the addition of SRFA as an alternative treatment option,the proportion of patients who can be treated with curative treatment has significantly increased.In the absence of prospective trials comparing thermal ablation and surgical resection,we recommend a patient-specific decision-making process.Future research to identify technical and clinical prognostic criteria,as well as molecular markers of tumor biology,may help select patients for ablation and subsequent outcomes.
