Co-expression of lignocellulase from termite and their endosymbionts / 生物工程学报

Natural lignocellulosic materials contain cellulose, hemicellulose, and lignin. Cellulose hydrolysis to glucose requires a series of lignocellulases. Recently, the research on the synergistic effect of lignocellulases has become a new research focus. Here, four lignocellulase genes encoding β-glucosidase, endo-1,4-β-glucanase, xylanase and laccase from termite and their endosymbionts were cloned into pETDuet-1 and pRSFDuet-1 and expressed in Escherichia coli. After SDS-PAGE analysis, the corresponding protein bands consistent with the theoretical values were observed and all the proteins showed enzyme activities. We used phosphoric acid swollen cellulose (PASC) as substrate to measure the synergistic effect of crude extracts of co-expressing enzymes and the mixture of single enzyme. The co-expressed enzymes increased the degradation efficiency of PASC by 44% compared with the single enzyme mixture; while the degradation rate increased by 34% and 20%, respectively when using filter paper and corn cob pretreated with phosphoric acid as substrates. The degradation efficiency of the co-expressed enzymes was higher than the total efficiency of the single enzyme mixture.

Molecular modification of β-glucosidase from the midgut of Macrotermes barneyi / 生物工程学报

Cellulose hydrolysis to glucose requires a series of cellulase enzymes, of which β-glucosidases play a crucial role. β-glucosidase (MbmgBG1) derived from the midgut of Macrotermes barneyi has higher glucose tolerance (maintaining more than 60% enzyme activity at 1.5 mol/L glucose). However, low enzyme activity and poor thermal stability limit the applications of β-glucosidase in food industries. Point mutants (F167L, T176C, E347I, R354K, N393G and V425M) were obtained by site-directed mutagenesis of non-conserved amino acids near conserved amino acids. Among them, the specific activities against to substrate pNPG of two mutants (F167L and R354K) were about 2-fold and 4-fold higher than that of MbmgBG1. Kcat/Km values were also higher than that of the wild-type, reflecting stronger affinity to the substrate and higher catalytic ability of mutants than MbmgBG1. When the glucose concentration was 1.5 mol/L, the enzyme activity of MbmgBG1 was about 60% of the original activity. F167L and R354K kept 60% enzymatic activity when the glucose concentrations of was 2.0 mol/L and 3.0 mol/L, respectively. These results lay a foundation for further studies on the catalytic efficiency of β-glucosidase.

Therapeutic efficacy of stereotactic radiotherapy with gamma knife on early-stage non-small-cell lung cancer and life quality of patients / 中华放射医学与防护杂志

Objective To evaluate the therapeutic efficacy of stereotactic body radiotherapy (SBRT) with gamma knife on stage Ⅰ-Ⅱ non-small-cell lung cancer(NSCLC)and the quality of life of the patients undergoing this therapy.Methods Twenty NSCLC patients with the median age of 76,10 at stage Ⅰ and 10 at stage Ⅱ who were unable or unwilling to undergo surgery were given SBRT with gamma knife at the doses of 3-6 Gy in 8-15 fractions,finished within 2 to 3 weeks.The prescription isodose line was 50％,the marginal dose was 39-56 Gy,the central dose was 78-112 Gy,and the total biologically effective dose was 51-83 Gy.The patients were observed after admission and followed up by chest CT 1,3,6,and 12 months after treatment until progressive disease or death.EORTC QLQ-LC43 questionnaire was used to investigate the changes in quality of life.Results The 20 patients were followed up for 24 (12-46) months.At six months after the treatment,the overall response rate was 80％,and the complete response rate was 35％.The 1,2 and 3-year local control rates were 100％,95％ and 95％,respectively.The 1,2 and 3-year overall survival rates were 95％,80％ and 50％ respectively; The 1,2,and 3-year progression free survival rates were 85％,64％ and 33％,respectively.The failure rate was 20％ and the rate of progress within the planning target volume was 5％.No acute toxicity at grade 3 and over occurred in any patient during the treatment.15％ of the patients developed grade 1-2 radiation pneumonia.Age,gender,pathologic index or not were weakly correlated with the overall survival.The emotional function was improved significantly after treatment (P ＜ 0.05),dyspnea and cough were improved at different degrees,however,not significantly.There were no significant changes in the physical function and symptoms,such as fatigue,lack of appetite,insomnia,etc.Conclusions Significantly improving the motional function and maintaining the quality of life,SBRT with gamma knife is effective for elderly NSCLC patients with high local control rate fair overall survival rate and few side effects.

Efficacy of gamma knife stereotactic radiotherapy and whole-brain radiotherapy in treatment of brain metastases / 中华放射医学与防护杂志

Objective To analyze the efficacy and prognosis of stereotactic radiotherapy (SRT) and whole-brain radiotherapy (WBRT) in treatment of brain metastases,and to observe the influence of temozolomide (TMZ) on survival rate during the period of radiotherapy.Methods A total of 52 patients with brain metastases were divided into two groups according to treatment methods,including 35 patients treated with WBRT plus SRT and 17 patients treated with SRT alone.WBRT dose was 1.8 - 3.0 Gy per fraction,one fraction a day,five fractions per week,with total dose of 30 - 40 Gy.After WBRT,gamma knife was performed with prescription isodose line of 45％ -70％ surrounding the planned target volume in WBRT + SRT group.The marginal dose was 12 - 15 Gy and the center dose was 20-30 Gy.In SRT group,the prescription isodosc line was 45％ - 70％ and the marginal dose was 36 - 40 Gy while the center up to 70 - 80 Gy.The follow up time was 1 - 2 years.Besides 20 patients in this study took temozolomide capsule during and after radiotherapy.The schedule of concomitant chemotherapy was temozolomide of 75 mg/m2 by oral administration every day until radiotherapy was over,and then temozolomide of 150 mg/m2 was taken for 3 -6 months after radiotherapy.Results The efficiency during 1 -3 months after treatment was 84.62％ in this study.In the WBRT + SRT group,the efficiency was 88.57％ and declined to 76.47％ in the SRT group.The six month-and one year-local control rate were 92.10％ and 85.20％,respectively.The average survival time of WBRT + SRT was 13.2 months and median survival time was 11 months.Six month-,one year-and eighteen months-survival rate were 71.40％,54.30％ and 14.30％,respectively.In the SRT group,the average survival time was 10.2 months and median survival time was 9 months.Six month-,one year- and eighteen month-survival rate were 41.20％,23.50％ and 5.88％,respectively,while those for RT + TMZ group were 80.00％,60.00％ and 10.00％.In comparison,those in RT group were 56.30％,37.50％ and 12.50％,respectively.Conclusions Effect of gamma knife stereotactic radiotherapy combined with WBRT is better than GK stereotactic radiotherapy alone in treatment of brain metastases.Compared with radiotherapy alone,concomitant temozolomide chemotherapy could improve the survival rate of the patients with brain metastases without increasirg adverse reactions significantly.