Neurogenesis in the dentate gyrus of the adult mammalian hippocampus has been proven in a series of studies, but the differentiation process toward newborn neurons is still unclear. In addition to the immunohistochemical study, electrophysiological membrane recordings of precursor cells could provide an alternative view to address this differentiation process. In this study, we performed green fluorescent protein (GFP)-guided selective recordings of nestin-positive progenitor cells in adult dentate gyrus by means of nestin-promoter GFP transgenic mice, because nestin is a typical marker for precursor cells in the adult dentate gyrus. The patch-clamp recordings clearly demonstrated the presence of two distinct subpopulations (type I and type II) of nestin-positive cells. Type I cells had a lower input resistance value of 77.1 M(Omega) (geometric mean), and their radial processes were stained with anti-glial fibrillary acidic protein antibody. On the other hand, type II nestin-positive cells had a higher input resistance value of 2110 MOmega and expressed voltage-dependent sodium current. In most cases, type II cells were stained with anti-polysialylated neural cell adhesion molecule. Taken together with a bromodeoxyuridine pulse-chase analysis, our results may reflect a rapid and dynamic cell conversion of nestin-positive progenitor, from type I to type II, at an early stage of adult neurogenesis in the dentate gyrus.

Intestinal glucose uptake is mainly performed by the sodium-dependent glucose transporter, SGLT1. The transport activity of SGLT1 was markedly inhibited by green tea polyphenols, this inhibitory activity being most pronounced in polyphenols having galloyl residues such as epicatechin gallate (ECg) and epigallocatechin gallate (EGCg). Experiments using brush-border membrane vesicles obtained from the rabbit small intestine demonstrated that ECg inhibited SGLT1 in a competitive manner, although ECg itself was not transported via SGLT1. The present results suggest that tea polyphenols such as ECg interact with SGLT1 as antagonist-like molecules, possibly playing a role in controlling the dietary glucose uptake in the intestinal tract.

Bimetallic nanoparticles consisting of gold and platinum were prepared by a citrate reduction method and complementarily stabilized with pectin (CP-Au/Pt). The percent mole ratio of platinum was varied from 0 to 100%. The CP-Au/Pt were alloy-structured. They were well dispersed in water. The average diameter of platinum nanoparticles (CP-Pt) was 4.7 +/- 1.5 nm. Hydrogen peroxide (H(2)O(2)) was quenched by CP-Au/Pt consisting of more than 50% platinum whereas superoxide anion radical (O(2)(-)) was quenched by any CP-Au/Pt. The CP-Au/Pt quenched these two reactive oxygen species in dose-dependent manners. The CP-Pt is the strongest quencher. The CP-Pt decomposed H(2)O(2) and consequently generated O(2) like catalase. The CP-Pt actually quenched O(2)(-) which was verified by a superoxide dismutase (SOD) assay kit. This quenching activity against O(2)(-) persisted like SOD. Taken together, CP-Pt may be a SOD/catalase mimetic which is useful for medical treatment of oxidative stress diseases.