Research progress in biosynthesis of podophyllotoxin and its derivatives / 生物工程学报

Podophyllotoxin (PTOX) is an aryl-tetralin lignan of plant origin found in some species of Podophyllum such as Dysosma versipellis, Diphylleia sinensis, and Sinopodophyllum hexandrum. Etoposide and teniposide are produced semisynthetically from PTOX and used clinically to treat several forms of cancer. As a typical representative of new drug discovery from natural products, the production of PTOX solely depends on extraction from plants, resulting in severe contradiction between supply and demand. With the advantages of unconstrained resources and eco-friendly reaction conditions, biosynthesis method has become a trend in the production of PTOX and its derivatives. In this review, we summarize the research progress of PTOX biosynthesis in plants and expound the functions of the key enzymes as well as their subcellular location. The synthetic biology for production of PTOX intermediates in a tobacco chassis is also introduced. Finally, the heterologous expression and biotransformation of PTOX in microorganisms is summarized, which sets the foundation for the efficient microbial production of PTOX using cell factories.

Analysis of provocative test results in 127 cases of suspected inducible urticaria / 中华皮肤科杂志

Objective To analyze the rate and distribution of positive provocative tests in patients with inducible urticaria,and to investigate the role of provocative tests in the etiological diagnosis of chronic urticaria.Methods Among patients who visited the special clinic for urticaria in the Department of Dermatology of the Third Affiliated Hospital,Sun Yat-sen University from January 2016 to December 2017,127 patients with suspected inducible urticaria were selected,and underwent 6 provocative tests for inducible urticaria,including delayed pressure urticaria provocative test (DPUPT),symptomatic dermographism provocative test (SDPT),vibratory angioedema provocative test (VAEPT),cold urticaria provocative test (CUPT),heat urticaria provocative test (HUPT),and aquagenic urticaria provocative test (AUPT).Statistical analysis was carried out by chi-square test for comparison of positive rates between male and female patients.Results Among the 127 patients with suspected inducible urticaria,106(83.46％) showed one or more positive provocative tests.The positive rate of SDPT was the highest (79.53％,101/127),followed by HUPT (22.05％,28/127) and CUPT (9.45％,12/127).The positive rate of HUPT was significantly higher in female patients (30.14％,22/73) than in male patients (11.11％,6/54;X2 =4.301,P ＜ 0.05).The patients with positive DPUPT,VAEPT and AUPT all showed positive SDPT responses.Among the 12 patients with positive CUPT reactions,11 showed positive SDPT responses.Among the 28 patients with positive HUPT reactions,26 showed positive SDPT responses.Of the 48 patients with one or more positive non-SDPT provocative tests,the patients with 2 positive non-SDPT provocative tests accounted for 18.75％ (9/48).Conclusion Provocation tests for inducible urticaria are of great clinical significance for the etiological diagnosis of chronic urticaria.

The changes in secretory phenotypes of senescent human gastric epithelial cells / 中华老年医学杂志

Objectives To investigate the effects of cell aging on the disorders relating to gastric mucosa aging.Methods A treatment of 200 μmol/L H2O2 was used to induce senescence of human gastric epithelial cell line GES-1,and the cell growth curve was monitored.Senescence secretory phenotypes were observed by detecting the protein level of p53 and p16INK4a with senescence-associated β-galactosidase(SA-β gal)staining and Western blot testing.The mRNA levels of senescence-associated secretory phenotype(SASP)factors in human gastric epithelial GES-1 cell including IL-1β,IL-6,IL-8,TGF-β、IFN-γ,and VEGF-A were detected by RT PCR.The mRNA expression levels of IL-1β,IL-6,IL-8,TGF-β,IFN-γ,and VEGF in the conditioned medium were detected by ELISA analysis.Results The 200 μmol/L H2O2-induced GES-1 cells stopped proliferating after 3 days of treatment,and cells enlarged and flattened at 10 days.The increased SA-β-gal staining(P＜0.001) and the increased expression levels of p53 and p16INK4a proteins indicated the success of establishing the aging model of GES-1.The mRNA levels of IL 1β,IL6,IL8,TGF-β,and IFNγ were higher(t=2.94,3.38,3.15,3.64,2.97;P=0.015,0.000,0.000,0.000,0.000)and the mRNA level of VEGF-A was lower(t=2.31,P =0.20) in senescent GES-1 cells than in the control group.In the conditioned medium of senescent GES-1 cells,the levels of IL-1β,IL6,IL8,TGF-β1,and IFNγ were higher in the H2O2-induced group [(3.12±0.21)μg/L,(4.26±0.15)μg/L,(3.37±0.14)μg/L,(5.34±0.19)μg/L,and(2.90±0.47)μg/L]than in the negative control group[(0.24±0.04,0.04±0.07,0.52±0.02,1.05±0.10,0.52±0.02,respectively,P＜0.001)],while the level of VEGF was lower in the H2O2-induced group than in the negative control group(0.21±0.03)μg/L vs (0.59±0.07)μg/L(P＜0.05).Conclusions The changes in senescence-associated secretory phenotype factors of the aging human gastric epithelial cells induced by oxidative stress may promote chronic gastritis and gastric cancer.

Magnetic resonance imaging of canine oral epithelial cells labeled with ultrasmall superparamagnetic iron oxide / 中国组织工程研究

BACKGROUND:Epithelial cel s are commonly used as the seed cel in tissue engineering;however, there is stil a lack of an effective in vivo noninvasive trace technology. OBJECTIVE:To investigate the feasibility of labeling canine oral epithelial cel s with ultrasmal superparamagnetie iron oxide (USPIO) and magnetic resonance imaging (MRI) in vitro. METHODS:Oral epithelial cel s from beagles were primary cultured, and then labeled by 0.75 mg/L poly-L-lysine combined with USPIO (0, 5, 10, 25, 50 and 100 mg/L), respectively. To determine the optimal dosage, the intracel ular iron expression was identified by Prussian blue staining, and the cel viability in different groups was detected by cel counting kit-8. Final y, 2×105 labeled cel s were suspended with 1 mL PBS buffer, and were screened using 3.0 T MR on T2*WI sequences in vitro. RESULTS AND CONCLUSION:USPIO prepared with 0.75 mg/L poly-L-lysine could successful y label dog oral epithelial cel s. Prussian blue staining showed intracel ular blue spots, and the intracel ular blue spots became more with the concentration increasing and saturated at the concentration of 25 mg/L. Cel counting kit-8 indicated that the cel viability did not change when the concentration<25 mg/L. Among the T2*WI sequences, the MRI signal intensity decreased with the concentration increasing. In conclusion, canine oral epithelial cel s can be effectively labeled with USPIO making no impact on cel viability when the concentration<25 mg/L, and MRI can be used to track these labeled cel s in vitro.