Transketolase (EC 2.2.1.1, TK) is a thiamine diphosphate-dependent enzyme that catalyzes the transfer of a two-carbon hydroxyacetyl unit with reversible C-C bond cleavage and formation. It is widely used in the production of chemicals, drug precursors, and asymmetric synthesis by cascade enzyme catalysis. In this paper, the activity of transketolase TKTA from Escherichia coli K12 on non-phosphorylated substrates was enhanced through site-directed saturation mutation and combined mutation. On this basis, the synthesis of tartaric semialdehyde was explored. The results showed that the optimal reaction temperature and pH of TKTA_M (R358I/H461S/R520Q) were 32 ℃ and 7.0, respectively. The specific activity on d-glyceraldehyde was (6.57±0.14) U/mg, which was 9.25 times higher than that of the wild type ((0.71±0.02) U/mg). Based on the characterization of TKTA_M, tartaric acid semialdehyde was synthesized with 50 mmol/L 5-keto-d-gluconate and 50 mmol/L non-phosphorylated ethanolaldehyde. The final yield of tartaric acid semialdehyde was 3.71 g with a molar conversion rate of 55.34%. Hence, the results may facilitate the preparation of l-(+)-tartaric acid from biomass, and provide an example for transketolase-catalyzed non-phosphorylated substrates.
Escherichia coli/genetics* ; Transketolase/chemistry* ; Tartrates ; Escherichia coli Proteins/genetics*

Objective To investigate the preopera ti ve diagnosis and the surgical treatment of primary retroperitoneal tumor(PRT). Methods The clinical dat a of 71 patients with PRT were retrospectively analyzed including clinical manif estation, radiologic studies, pathologic examination and surgical procedures. Results There were 32 cases of benign tumor, 38 cases of malignant tumor and 1 case of borderline tumor. Of the 32 patients with benign tumor, 31 underwent complete surgical resection. Of the 38 patients with malignant tumor, 29 underwent complete resection. One patie nt with borderline tumor underwent total resection. The 5-year survival rate of benign PRT was 89.29%, the 5-year survival rate of malignant PRT was 20.80%. Four cases of recurrent benign PRT underwent complete resection. Ten cases of r ecurrent malignant PRT underwent complete resection and 3 underwent partial rese ction. ConclusionsRadiolog ical study is crucial for the diagnosis. Complete resection is the key for the t reatment of PRT.

Objective To establish and apply the systemic caring and nursing model,the five-heart nursing service model. Methods The five-heart nursing service content was designed,the five-heart nursing service organization was perfected,the five-heart nursing service manual books were compiled and the satisfaction questionnaires for five-heart nursing service were designed.Three tryout departments were selected and the nursing staff was trained by human theory and five-heart nursing service amenity and flow according to the five-heart nursing service requirement. Results The patients satisfaction degree, medical entanglemant complaint and praise after the application of five-heart nursing service were greatly improved compared with those of before its application (P ＜ 0.05). Conclusion The application of five-heart nursing service supplied systemic caring and nursing for patients and it proved effective to improve patients satisfaction degree.

Objective To investigate the correlation between CT parameters of erector spinae muscle(ESM)and pulmonary function in elderly patients with chronic obstructive pulmonary disease(COPD),and to analyze its predictive value for the prognosis of patients.Methods A total of 120 COPD patients were included as the case group(including 60 cases in stable stage and 60 cases in acute exacerbation stage),and 60 smokers were selected as the control group.The differences of ESM CT parameters and pulmonary function parameters in each group were compared.According to the prognosis of COPD,patients were divided into good prognosis group(n=106)and poor prognosis group(n=14),and the predictive efficacy of ESM CT parameters on the prognosis of COPD patients was analyzed.Results The pulmonary function parameters,ESM cross sectional area(CSA)(ESMCSA)and ESM local volume in the case group were significantly lower than those in the control group(P<0.05).ESMCSA and ESM local volume were positively correlated with inspiratory capacity(IC),vital capacity(VC),forced vital capacity(FVC)and forced expiratory volume in one second(FEV1)(P<0.001).The average muscle density of ESM was positively correlated with IC,VC and FVC(P<0.05),but not with FEV1.The area under the curve(AUC)of ESMCSA and ESM local volume in predicting poor prognosis of COPD patients was 0.769[95%confidence interval(CI)0.661-0.876]and 0.827(95%CI 0.734-0.919),respectively.Conclusion There is a certain correlation between the CT parameters of ESM and the pulmonary function parameters of COPD patients,among which the ESMCSA and the ESM local volume have high predictive efficacy for the prognosis of COPD patients.

DNA double-strand break (DSB) is the most severe form of DNA damage, which is repaired mainly through high-fidelity homologous recombination (HR) or error-prone non-homologous end joining (NHEJ). Defects in the DNA damage response lead to genomic instability and ultimately predispose organs to cancer. Nicotinamide phosphoribosyltransferase (Nampt), which is involved in nicotinamide adenine dinucleotide metabolism, is overexpressed in a variety of tumors. In this report, we found that Nampt physically associated with CtIP and DNA-PKcs/Ku80, which are key factors in HR and NHEJ, respectively. Depletion of Nampt by small interfering RNA (siRNA) led to defective NHEJ-mediated DSB repair and enhanced HR-mediated repair. Furthermore, the inhibition of Nampt expression promoted proliferation of cancer cells and normal human fibroblasts and decreased β-galactosidase staining, indicating a delay in the onset of cellular senescence in normal human fibroblasts. Taken together, our results suggest that Nampt is a suppressor of HR-mediated DSB repair and an enhancer of NHEJ-mediated DSB repair, contributing to the acceleration of cellular senescence.
Antigen-Antibody Complex ; metabolism ; Antigens, Nuclear ; genetics ; metabolism ; Carrier Proteins ; genetics ; metabolism ; Cell Line ; Cell Proliferation ; Cellular Senescence ; DNA Breaks, Double-Stranded ; DNA End-Joining Repair ; DNA Repair ; DNA-Activated Protein Kinase ; genetics ; metabolism ; DNA-Binding Proteins ; genetics ; metabolism ; Fibroblasts ; cytology ; HeLa Cells ; Homologous Recombination ; genetics ; physiology ; Humans ; Ku Autoantigen ; Nicotinamide Phosphoribosyltransferase ; genetics ; metabolism ; physiology ; Nuclear Proteins ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; beta-Galactosidase ; metabolism

Objective:To investigate the effects of mixed probiotics on food allergy and the underlying mechanism.Methods:BALB/c mice on the 15 th day of pregnancy were randomly (random number table method) classified into the control group, food allergy model group and mixed probiotics group.Mice in the food allergy model and mixed pro-biotics group were subjected to ovalbumin (OVA) sensitization after birth, and those in the mixed probiotics group were then given probiotic solution by gavage from day 21 to day 35.Mice in control group were similarly given 9 g/L saline.Twenty-four hours after the last OVA sensitization, intestinal histopathological sections were prepared to observe intestinal pathological changes.Blood smears were prepared to detect eosinophil count.In addition, serum samples were collected to measure cytokine levels and OVA specific antibodies.The number of dendritic cells (DCs) and regulatory T cells (Tregs) in mouse mesenteric lymph nodes was calculated.Differences among 3 groups were compared by the One- Way ANOVA or Kruskal- Wallis H test. Results:Compared with those of food allergy model group, diarrhea score, the ratio of eosinophils and serum levels of interleukin(IL)-4, IL-5, IL-13, mast cell protease 1 (MCPT-1), and OVA specific antibodies IgE and IgG were significantly lower in mixed probiotics group[(2.00±0.71) points vs.(3.22±0.97) points, (2.28±1.61)% vs.(10.99±2.26)%, (413.68±22.81) ng/L vs.(708.78±27.66) ng/L, (36.64±3.74) ng/L vs.(46.05±4.95) ng/L, (201.37±65.61) ng/L vs.(495.22±96.66) ng/L, (31 924.15±1 177.77) ng/L vs.(36 175.77±618.29) ng/L, (9.10±8.08) ng/L vs.(19.69±0.84) ng/L, (30.50±8.81) ng/L vs.(190.32±6.40) ng/L], while IL-10 level was significantly higher[(164.12±3.88) ng/L vs.(123.90±7.31) ng/L] ( t=3.37, 8.72, 16.07, 3.90, 7.40, 7.95, 3.91, 44.00 and 7.76, respectively, all P<0.01). Compared with those of food allergy model group, programmed cell death ligand 1 (PD-L1) level on the surface of CD 103+ DCs and CD 103+ CD 80-CD 40-DCs, the proportion of Tregs in CD4 + T cells, and the level of programmed cell death 1 (PD-1) on the surface of Tregs were significantly higher in mixed probiotics group[(75.59±0.45)% vs.(45.60±4.73)%, (67.56±1.87)% vs.(37.12±6.07)%, (8.24±0.69)% vs.(6.20±0.66)%, (11.25±3.12)% vs.(4.08±2.33)%]( t=7.88, 4.48, 3.63 and 3.71, all P<0.01). Conclusions:Mixed probiotics can alleviate the symptoms of food allergy and inflammatory response of young rats through mediating Tregs via the PD-1/PD-L1 pathway.