A rational design to enhance the resistance of Escherichia coli phytase appA to trypsin.

Escherichia coli phytase appA, which hydrolyzes phytate, has been widely applied as an important feed supplement, but its resistance to trypsin needs to be improved. Six putative solvent-accessible amino acid residues (K74, K75, K180, R181, K183, and K363), which could be easily attacked by trypsin, were selected to improve trypsin tolerance of Escherichia coli phytase appA. Inspection of the three-dimensional structure and computational design via hydrogen bond analysis, six optimal mutation sites of K74D/K75Q/K180N/R181N/K183S/K363N, which strengthened the hydrogen bonding, were performed to generate three mutants. Results showed that the most beneficial mutant appA-M6 had a specific activity of 3262 U/mg with molecular weight of approximately 52-55 kDa. Similar to appA-WT, the optimal pH (4.5) and temperature (60 °C) of appA-M6 were unchanged. Compared with appA-WT, appA-M6 showed a significant enhancement (p < 0.05) in resistance to trypsin and a 3.8 °C increase in melting temperature (Tm). We concluded that introduction of hydrogen bonds and N-glycosylation modification resulted in decreased enzyme flexibility and increased the enzyme stability against proteolysis and thermal denaturation. The mutant appA-M6 generated in this study could be applied for the large-scale commercial production of phytase and thus could benefit the food and feed industry.

Effects of a controlled-release fertilizer on yield, nutrient uptake, and fertilizer usage efficiency in early ripening rapeseed (Brassica napus L.).

BACKGROUND: Nitrogen (N), phosphorous (P), and potassium (K) are critical nutrient elements necessary for crop plant growth and development. However, excessive inputs will lead to inefficient usage and cause excessive nutrient losses in the field environment, and also adversely affect the soil, water and air quality, human health, and biodiversity. METHODS: Field experiments were conducted to study the effects of controlled-release fertilizer (CRF) on seed yield, plant growth, nutrient uptake, and fertilizer usage efficiency for early ripening rapeseed (Xiangzayou 1613) in the red-yellow soil of southern China during 2011-2013. It was grown using a soluble fertilizer (SF) and the same amounts of CRF, such as SF1/CRF1 (3750 kg/hm2), SF2/CRF2 (3000 kg/hm2), SF3/CRF3 (2250 kg/hm2), SF4/CRF4 (1500 kg/hm2), SF5/CRF5 (750 kg/hm2), and also using no fertilizer (CK). RESULTS: CRF gave higher seed yields than SF in both seasons by 14.51%. CRF4 and SF3 in each group achieved maximum seed yield (2066.97 and 1844.50 kg/hm2, respectively), followed by CRF3 (1929.97 kg/hm2) and SF4 (1839.40 kg/hm2). There were no significant differences in seed yield among CK, SF1, and CRF1 (P>0.05). CRF4 had the highest profit (7126.4 CNY/hm2) and showed an increase of 12.37% in seed yield, and it decreased by 11.01% in unit fertilizer rate compared with SF4. The branch number, pod number, and dry matter weight compared with SF increased significantly under the fertilization of CRF (P<0.05). The pod number per plant was the major contributor to seed yield. On the other hand, the N, P, and K uptakes increased at first and then decreased with increasing the fertilizer rate at maturity, and the N, P, and K usage efficiency decreased with increasing the fertilizer rate. The N, P, and K uptakes and usage efficiencies of the CRF were significantly higher than those of SF (P<0.05). The N accumulation and N usage efficiency of CRF increased by an average of 13.66% and 9.74 percentage points, respectively, compared to SF. In conclusion, CRF significantly promoted the growth of rapeseed with using total N as the base fertilizer, by providing sufficient N in the later growth stages, and last by reducing the residual N in the soil and increasing the N accumulation and N usage efficiency.

[Research on survey analysis and development strategies of traditional Chinese preparations in Guangdong Province hospitals].

OBJECTIVE: To provide reference for the government to formulate policies and medical institution to formulate development plan, the present situation of medical institutions of traditional Chinese preparation and some countermeasures for developing the research of traditional Chinese preparation in Guangdong province were studied. METHODS: Combined with development situation of traditional Chinese preparation of medical institutions in Guangdong province in recent years, the development countermeasure of traditional Chinese preparation was discussed. RESULTS: In order to promote the development of traditional Chinese preparation of medical institutions, suggestions and countermeasures for the government and related departments were proposed. CONCLUSION: Government departments should formulate policies to support the development of traditional Chinese preparation, the medical institutions should make scientific development planning, strengthen the construction of hardware and software and develop special traditional Chinese preparation to promote the healthy development of traditional Chinese preparation.

Oxaliplatin/5-fluorouracil/leucovorin (FOLFOX4) regimen as an adjuvant chemotherapy in the treatment of advanced jejunal adenocarcinoma: a report of 2 cases.

OBJECTIVE: To present our clinical experience of 5-fluorouracil/leucovorin/oxaliplatin (FOLFOX4) regimen administered as an adjuvant chemotherapy to 2 patients with advanced jejunal adenocarcinoma. CASE PRESENTATION AND INTERVENTION: A 55-year-old woman presented with recurrent upper abdominal pain, nausea and vomiting. A small bowel series as well as the abdominal computed tomography scan revealed an irregular narrowing lesion at the proximal jejunum. The patient then underwent an exploratory laparotomy and the jejunal adenocarcinoma with localized peritoneal metastasis was found (R0 resection, T3N1M1, stage IV). Chemotherapy with FOLFOX4 regimen of 12 cycles was initiated after the curative resection. No adverse event was observed during the period of chemotherapy. She has been well without evidence of recurrence for over 20 months postoperatively. The second case was a 77-year-old female presenting with mechanical ileus. Surgical exploration revealed a proximal jejunal adenocarcinoma with regional lymph node involvement (R0 resection, T3N1M0, stage III). She also received the FOLFOX4 chemotherapy of 12 cycles with an uneventful course. No obvious toxicity developed except for temporary grade I peripheral neuropathy and skin eruption. This patient has survived well and has been free of this disease for over 12 months since the operation. CONCLUSION: This report showed that adjuvant chemotherapy with FOLFOX4 regimen seems effective and well tolerated in these 2 patients with advanced jejunal adenocarcinoma. Further investigation of a large number of patients with long-term follow-up is needed to confirm these findings.

Isolation and characterization of human gastric cell lines with stem cell phenotypes.

AIM: The aim of this study was to develop an in vitro human gastric stem and/or progenitor cell model that may be used to study the mechanism of gastric carcinogenesis induced by Helicobacter pylori infection. METHODS: Human gastric biopsy was minced and digested with collagenase and dispase and cultured in a low-calcium medium (serum-free keratinocyte medium; keratinocyte-SFM) supplemented with N-acetyl-L-cysteine and L-ascorbic acid 2-phosphate. Actively proliferating epithelial colonies with sustained growth were isolated and characterized for karyotype and phenotypes related to stem cell characteristics including proliferation and differentiation potential, ability of anchorage-independent growth (AIG), gap junctional intercellular communication (GJIC) and the expression of Oct-4, a transcription factor previously shown to be expressed in embryonic stem cells, adult stem cells and undifferentiated tumor cells. To study the carcinogenic effect of H. pylori infection, gastric stem and/or progenitor cells were incubated with H. pylori culture products and/or N-methyl-N-nitro-N-nitrosoguanidine (MNNG), a chemical carcinogen, to see the telomerase activation. RESULTS: Multiple cell lines with stem cell features were isolated by this new cell culture method. The results based on detailed characterization of one cell clone, KMU-GI2, revealed stem cell features of these cells. The initial clone contained mostly undifferentiated epithelial-like cells, which, upon subculture and propagation, gave rise to a heterogeneous cell population. Single cell-derived subclones, similar to the parental population, retained high differentiation potential and were capable of giving rise to many morphologically different cell types (i.e. epithelial-like, glial or neuron-like, round and various peculiar-shaped cells). Although these cells were normal in karyotype and competent in GJIC, they had the ability to grow in soft agar. Cells expressing epithelial membrane antigen (EMA), mucin 5AC, glial fibrillary acidic protein (GFAP), cytokeratin-18 (CK-18), trefoil factor 1 (TFF-1) and Oct-4 were found in the cell culture, but not E-cadherin-, gastrin- or telomerase-expressing cells. Furthermore, spontaneously immortalized non-tumorigenic clones could be derived from the cell population. After treating these cell cultures with the chemical carcinogen, MNNG and H. pylori culture products for 5 days, telomerase activity and telomerase mRNA expression were significantly elevated, while treatment with either of them showed no effect. CONCLUSION: The new cell culture method can be used to develop gastric epithelial cell clones with sustained growth from endoscopic biopsy. The gastric cell clone showed several stem and/or progenitor cell phenotypes (i.e. the ability of AIG, high differentiation capacity, high susceptibility to spontaneous immortalization and the expression of Oct-4). The telomerase expression in these gastric stem and/or progenitor cells can be upregulated by exposure to H. pylori culture products and MNNG, an important step in neoplastic transformation. These results show that putative human gastric stem and/or progenitor cell clones can be developed by our method and these cells could be useful for studying the mechanisms of human gastric carcinogenesis including the mechanism of action of H. pylori, as well as the regulation of the proliferation and differentiation of human gastric mucosa.

[Studies on flavoniod constituents of Hedysarum multijugum].

AIM: To study the chemical constituents from Hedysarum multijugum. METHODS: The compounds were separated by chromatography methods, their structures were identified by spectral analysis. RESULTS: Six compounds were isolated and identified as beta-sitosterol (1), 7-hydroxy-4'-methoxy isoflavone (2), betulic acid (3), 1,7-dihydroxy-3, 9-dimethoxy pterocarpene (4), 5, 7-dihydroxy-8-C-prenyl-4'-methoxy isoflavone (5) and 5, 7-dihydroxy-4'-methoxy isoflavone (6). CONCLUSION: Compound 4 is a new compound and the others were obtained from the plant for the first time.