Tunable surface plasmon-polaritons based on quantum coherence.

Tunable surface plasmons on the interface of a multilevel atomic medium with a cross coupling of the electric and magnetic components of a plasmonic field are investigated. The strong chirality resulting from the quantum coherence leads to some exciting properties of the surface plasmons. Compared to the traditional chiral-metal interface, surface plasmonic mode can still be found at the interface between such atomic media and a dielectric even when both the permittivity and the permeability of the medium are positive. This is in contrast to the conventional plasmonic systems where the signs of the permittivities or permeabilities on the two sides of the interface are opposite. We call this phenomenon an electromagnetically induced plasmon. Additionally, as the chirality and effective refractive index of the atomic medium are dependent on the intensity and phase of the controlling field, we can conveniently manipulate the properties of the surface plasmons.

Effects of astragalosides on cultured islets after cryopreservation in rats.

OBJECTIVE: To explore the effects of AST (astragalosides) on cultured rat islet yield, purity, and function after cryopreservation in rats. METHODS: Pancreatic islets were isolated from 30 Sprague-Dawley rats using the standard technique of collagenase P digestion and discontinuous Ficoll gradient purification. After thaw, the islets were randomly divided into AST group and control group (n=15). Next, the islet cells were cultured in AST-containing medium or standard medium for 7, 14, and 21 days after cryopreservation and thaw. The quantity, purity, and survival rate were calculated in the two groups before and after culture. Then the in vitro and in vivo function was observed in diabetic rats after islet transplantation. RESULTS: The quantity and purity of islets had no difference between the two groups before culture (P>.05) while the difference after culture was significantly (P<.05). The survival rate of islets was 48% in AST group and 32% in the control group 21 days after thaw (P<.05). After 3 days, there was significantly a higher simulation index in the AST group than in the control group (P<.05). There was a significant difference in blood glucose and insulin concentrations between the groups after 3 days (P<.05). CONCLUSION: AST can be added to the culture medium to reduce the loss of islet cryopreservation and be intravenously injected to improve culture islet function in vitro and prolong islet graft survival in diabetic rats.

Serum concentration fluctuation and bioavailability comparison between indomethacin sustained-release and conventional capsules during steady state.

The comparison between indomethacin conventional capsule (CC) po 25 mg q 8 h or 25 mg tid and indomethacin sustained-release capsule (SRC) po 25 mg bid in human by crossover design showed that both maximal serum concentration (Cmax) and fluctuation index (FI%) of SRC were significantly lower than those of CC during steady state (P < 0.01). No practical differences were observed between the 2 preparations in the trough serum concentration (Cmin) and area under serum concentration-time profiles (AUC0-tau) (P > 0.05). The time period reaching maximal serum concentration (Tmax) of SRC was much more delayed than that of CC (P < 0.01). It suggested that SRC possesses a better controlled release property and could avoid a higher serum peak concentration of CC.

[Bioavailability of a controlled-release suspension of phenylpropanolamine in healthy volunteers].

A high-performance liquid chromatographic analysis of phenylpropanolamine (PPA) in human plasma is presented. Using direct UV detection the method is sufficiently sensitive to 25 ng/ml for PPA. Single-dose pharmacokinetics of PPA in 10 healthy volunteers taking controlled release suspension (C) or tablet (T), each containing 150 mg PPA was compared. The study described here has shown that the (C) AUC(0-infinity)/(T) AUC(0-infinity) = 1.02 (P greater than 0.4). The controlled-release product of PPA is equivalent to PPA tablet.