Gas Sensing Properties of Epitaxial LaBaCo2O5.5+δ Thin Films.

Chemical reactivity and stability of highly epitaxial mixed-conductive LaBaCo2O5.5+δ (LBCO) thin films on (001) LaAlO3 (LAO) single-crystalline substrates, fabricated by using pulsed laser deposition system, were systematically investigated. Microstructure studies from x-ray diffraction indicate that the films are c-axis oriented with the interface relationship of [100]LBCO//[100]LAO and (001)LBCO//(001)LAO. LBCO thin films can detect the ethanol vapor concentration as low as 10 ppm and the response of LBCO thin film to various ethanol vapor concentrations is very reliable and reproducible with the switch between air and ethanol vapor. Moreover, the fast response of the LBCO thin film, as the p-type gas sensor, is better than some n-type oxide semiconductor thin films and comparable with some nanorods and nanowires. These findings indicate that the LBCO thin films have great potential for the development of gas sensors in reducing/oxidizing environments.

Constitutive expression, purification and characterization of bovine prochymosin in Pichia pastoris GS115.

Chymosin can specifically break down the Phe105-Met106 peptide bond of milk κ-casein to form insoluble para-κ-casein, resulting in milk coagulation, a process that is used in making cheese. In this study, in order to obtain an alternative milk coagulant which is safe and efficient, and simultaneously can produce cheese with a good taste, bovine prochymosin B was chosen and constitutively expressed to a high level in Pichia pastoris. The recombinant chymosin was expressed mainly as a secretory form, and it exhibited milk-clotting activity. It was purified by ammonium sulfate fractionation, anion exchange, followed by cation exchange chromatography. A final yield of 24.2% was obtained for the purified enzyme, which appeared as a single band in SDS-PAGE having a molecular mass of approximate 36 kDa. Proteolysis assay showed that it specifically hydrolyzed κ-casein. It was stable at 25-50°C and had optimal activity at 37°C and pH 4.0. The activity of the recombinant chymosin was activated by cations such as Mn(2+), Fe(3+), Mg(2+) and Na(+), but inhibited by K(+), Co(2+), Zn(2+), Ni(2+), and to a lesser extent by Cu(2+). These results suggested that recombinant bovine chymosin is an acid milk coagulant, and it could be considered as a safe and efficient enzyme suitable for use in cheese production.

Protective effects of bilobalide on amyloid beta-peptide 25-35-induced PC12 cell cytotoxicity.

AIM: To study the effect of bilobalide, a terpene extracted from the leaves of Ginkgo biloba, on beta-amyloid peptide fragment 25-35 (A beta 25-35)-induced PC12 cell cytotoxicity. METHODS: 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay were used to measure the viability of PC12 cells. Thiobarbituric acid-reactive substances were measured to determine lipid peroxidation of cells. Antioxidant enzymes in PC12 cells were detected. RESULTS: Treatment of PC12 cells with A beta 25-35 (100 mumol.L-1) for 24 h caused a great decrease in cell viability (P < 0.01 compared with control). Bilobalide 25-100 mumol.L-1 dose-dependently attenuated the cytotoxic effect of A beta 25-35. Bilobalide also inhibited A beta 25-35 (100 mumol.L-1)-induced elevation of lipid peroxidation and decline of antioxidant enzyme activities. CONCLUSION: Bilobalide protected PC12 cells from A beta 25-35-induced cytotoxicity.

Bilobalide promotes expression of glial cell line-derived neurotrophic factor and vascular endothelial growth factor in rat astrocytes.

AIM: To study the effects of bilobalide on the expression of glial cell line-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF) in rat astrocytes in vitro. METHODS: Semiquantification polymerase chain reaction (SQ-PCR) was used to investigate GDNF and VEGF mRNA expression in the astrocytes after bilobalide (5, 15, 50, 100 mumol.L-1) treatment. Immunohistochemistry method was used to detect GDNF and VEGF protein expression in cells treated with bilobalide 50 mumol.L-1 for 24 h. RESULTS: GDNF and VEGF mRNA increased markedly after astrocytes were treated with bilobalide 50 mumol.L-1 for 12 h. GDNF and VEGF protein were detected in the cytoplasm of astrocytes after the cells were treated with bilobalide 50 mumol.L-1 for 24 h. CONCLUSION: Bilobalide induced GDNF and VEGF expression in the cultured astrocytes.

Protective effect of bilobalide against nitric oxide-induced neurotoxicity in PC12 cells.

AIM: To examine the effects of bilobalide on nitric oxide-induced neurotoxicity in pheochromocytoma-derived PC12 cells (PC12 cells). METHODS: PC12 cell survival was monitored by LDH release and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays. Superoxide dismutases (SOD) and catalase (CAT) activities were measured based on their abilities to inhibit the oxidation of epinephrine by the xanthine-xanthine oxidase system or to decompose H2O2 respectively. The content of malondialdehyde (MDA) was measured by a fluorometric assay to indicate the lipid peroxidation. RESULTS: 3-Morpholinosydnonimine (SIN-1, 50-300 mumol.L-1) induced PC12 cell damage. After the cells had been pretreated with 10 mumol.L-1 bilobalide for 24 h, the cell viability was increased to 91% +/- 30% from 52% +/- 14% in SIN-1 alone group. Moreover, the activities of SOD and CAT were increased after cells were treated with bilobalide. CONCLUSION: The NO-induced neurotoxicity can be protected by bilobalide in PC12 cells. The bilobalide-induced increase in SOD and CAT activities may serve as one of the mechanisms underlying the neuroprotective effect of bilobalide.

[Pathomorphological observation of oviducts of women with inserted IUDs].

PIP: The tissues of isthmus tubae uterinae from 101 women with IUDs in place and 113 women without IUDs were observed by microscopy. The rate changes of the covered area of ciliated cells were observed in oviducts in 30 patients with IUDs and 17 without. Results showed that the incidence of salpingitis was 71.29% in the IUD group and 56.64% in the controls (p.05), and the rate of covered area of ciliated cells was 22.63% in the IUD group and 38.18% in the controls (p.05). It is suggested that salpingitis incidence was raised and the rate of covered area of ciliated cells reduced significantly in relation to IUD use. (author's modified)^ieng

[Chemical constituents of Dysosma aurantiocaulis (H.-M.) Hu and Dysosma pleianthum Woods].

Roots of D. aurantiocaulis and D. pleianthum contain ten lignans: picropodophyllin, podophyllotoxin, 4'-demethylpodophyllotoxin, diphyllin, dehydropodophyllotoxin, podophyllotoxone, picropodophyllone, isopicropodophyllone, 4'-demethylpodophyllotoxone and dysosmajol; two anthraquinones: physcion and dysoanthraquinone. A HPLC method for the identification of aryltetralin lignans is described.