Preparation of novel poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted core-shell magnetic chitosan microspheres and immobilization of lactase.

Poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted magnetic chitosan microspheres (HG-MCM) were prepared using reversed-phase suspension polymerization method. The HG-MCM presented a core-shell structure and regular spherical shape with poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) grafted onto the chitosan layer coating the Fe3O4 cores. The average diameter of the magnetic microspheres was 10.67 µm, within a narrow size distribution of 6.6-17.4 µm. The saturation magnetization and retentivity of the magnetic microspheres were 7.0033 emu/g and 0.6273 emu/g, respectively. The application of HG-MCM in immobilization of lactase showed that the immobilized enzyme presented higher storage, pH and thermal stability compared to the free enzyme. This indicates that HG-MCM have potential applications in bio-macromolecule immobilization.

Lactulose biosynthesis by ß-galactosidase from a newly isolated Arthrobacter sp.

Lactulose, a ketose disaccharide, is used in both pharmaceutical and food industries. This study was undertaken to screen and isolate potent ß-galactosidase-producing bacteria and to evaluate their enzymatic production of lactulose. Soil samples from fruit gardens were collected. One isolate designated LAS was identified whose cell extract could convert lactose and fructose into lactulose. The 16S rDNA gene analysis of LAS revealed its phylogenetic relatedness to Arthrobacter sp. The ß-galactosidase produced by LAS was purified 15.7-fold by ammonium sulfate precipitation and subsequent Phenyl-Sepharose hydrophobic chromatography. The optimum pH and temperature for lactulose synthesis by this ß-galactosidase were 6.0 and 20 °C, respectively. The low optimum temperature of this enzyme compared to the currently used ones for lactulose production has the advantage of reducing the nonenzymatic browning in biotransformations. The results indicated that Arthrobacter could be used as a novel bacterial ß-galactosidase source for lactulose production.

Altered expression of connexin43 and phosphorylation connexin43 in glioma tumors.

In this study, we aim to evaluate the connexin (Cx43) and phosphorylation Cx43 (p-Cx43) expression of human glioma tumors and correlate their expression with degrees of malignancy and proliferation, apoptosis, and migration activity of tumors. Cx43 and p-Cx43 expression were examined by Western blot analysis and immunohistochemical staining. The U251 cell viability was measured by MTT analysis. The apoptosis and migration were also evaluated by flow cytometric analysis and fluoroblok transwell chambers, respectively. We found that the Cx43 expression were significantly downregulated in in malignant glioma (WHO grade III and IV), compared to the malignant glioma (WHO grade I and II) and the p-Cx43 expression levels of malignant glioma (WHO grade III and IV) were significantly increased (P<0.05), compared to the malignant glioma (WHO grade I and II) at immunohistochemical analysis. After treatment of cells with a specific inhibitor of PKC, MAPK, and PTK inhibitors, the cell viability and migration were significantly decreased, while the apoptosis was slightly induced. In conclusion, the Cx43 expression level is inversely correlated with the tumor grade and proliferation and migration activity of tumor. Higher p-Cx43 expression level in high tumor grade suggests that a complex mechanism is involved in the suppression of tumor growth by connexins.