Anti-epileptic effect of Ganoderma lucidum polysaccharides by inhibition of intracellular calcium accumulation and stimulation of expression of CaMKII α in epileptic hippocampal neurons.

PURPOSE: To investigate the mechanism of the anti-epileptic effect of Ganoderma lucidum polysaccharides (GLP), the changes of intracellular calcium and CaMK II α expression in a model of epileptic neurons were investigated. METHOD: Primary hippocampal neurons were divided into: 1) Control group, neurons were cultured with Neurobasal medium, for 3 hours; 2) Model group I: neurons were incubated with Mg(2+) free medium for 3 hours; 3) Model group II: neurons were incubated with Mg(2+) free medium for 3 hours then cultured with the normal medium for a further 3 hours; 4) GLP group I: neurons were incubated with Mg(2+) free medium containing GLP (0.375 mg/ml) for 3 hours; 5) GLP group II: neurons were incubated with Mg(2+) free medium for 3 hours then cultured with a normal culture medium containing GLP for a further 3 hours. The CaMK II α protein expression was assessed by Western-blot. Ca(2+) turnover in neurons was assessed using Fluo-3/AM which was added into the replacement medium and Ca(2+) turnover was observed under a laser scanning confocal microscope. RESULTS: The CaMK II α expression in the model groups was less than in the control groups, however, in the GLP groups, it was higher than that observed in the model group. Ca(2+) fluorescence intensity in GLP group I was significantly lower than that in model group I after 30 seconds, while in GLP group II, it was reduced significantly compared to model group II after 5 minutes. CONCLUSION: GLP may inhibit calcium overload and promote CaMK II α expression to protect epileptic neurons.

[Study on concentration quenching and energy transfer in Ln3+ (Ln = Tb, Tm, Eu) in Y2O3 nanocrystal powders].

Nano-powders Y2O3 with various particle sizes and different doping concentrations of Ln (Ln = Tb, Tm, Eu) were prepared by using a combustion technique. The bulky powders doped with concentrations corresponding to nano-powders were obtained by annealing the nano-powders at high temperature. The emission spectra, XRD spectra and TEM were used in the present study. The concentration quenching of luminescent centers and energy transfer between luminescent centers in Y2O3 : Ln nanocrystal powders were investigated. It was found that the behaviors of luminescence concentration quenching for 5D4 --> 7F5 : Tb3+ and 5D0 --> 7F2 : Eu3+ in nano-powders are similar to that in bulky powders. On the contrary, the quenching concentrations for 5D3 --> 7F5 : Tb3+ and 1D2 --> 3H4 : Tm3+ are distinctly higher than that in bulk powders. This owes to the size confinement effect: the interface of nanocrystal particles can stop a portion of the energy transfer, which happens in the bulk ones, between luminescent centers. The size confinement effect can bring different influences to the different types of energy transfer. For instance, it will restrain the energy transfer (governed by electric dipole-dipole interaction) between the ions in long distances, and will hardly affect the energy transfer (governed by exchange interaction) between the ions locating at near intervals.

[Preparation of alpha-Gd2 (MoO4)3 red emitting phosphor for white light emitting diodes and its luminescence study].

A novel red phosphor alpha-Gd2 (MoO4)3: Eu was synthesized by conventional solid state reaction method with the starting materials: Gd2O3, MoO3 and Eu2O3. The effects of flux and Eu concentration on the crystal structure, morphology and luminescent properties of the phosphors were investigated. The results showed that non-agglomeration phosphors with regular morphology and fine size were produced after the mixture being calcined at 800 degrees C for 4h with 3% NH4F as flux. The main emission peak of the samples is at 613 nm. The excitation spectrum showed that this phosphor can be effectively excited by ultraviolet (UV) (395 nm) and blue (465 nm) light, nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. The alpha-Gd2 (MoO4)3 phosphor may be a good candidate phosphor for solid state lighting application.

[Synthesis and luminous characteristics of Y (P, V)O4: Eu3+ phosphors for PDP].

Y(P, V)O4 :Eu3+ phosphors with good morphology for plasma display panels have been prepared via coprecipitation reaction. The phosphor was characterized by SEM and photoluminescence under UV (325 nm)and VUV (147 nm) excitation. The emission spectra depending on temperature under 325 nm excitation by laser indicated that there exist energy transfer between VO4(3-) group and Eu3+ ion. Under 147 nm excitation, the most intense emission peaks of commercial (Y,Gd)BO3 :Eu3+ phosphor range around 593 nm, and those of Y(P, V)O4 :Eu3+ phosphors prepared by coprecipitation reaction ranged around 619 nm. The red emission color purity of Y(P, V)O4 :Eu3+ phosphor is much better than that of (Y,Gd)BO3: Eu3+, and its relative emission intensity is almost close to that of the commercial phosphor.