Actions of genistein on contractile response of smooth muscle isolated from guinea pig gallbladder

BACKGROUND: Defective contractile motility of the gallbladder is an important factor for gallstone formation. Estrogen might increase the risk of gallstones and cholecystitis, and estradiol inhibits the contractile activity of isolated strips of guinea pig gallbladder. The potential risks associated with hormone replacement therapy (HRT) include symptomatic gallstones. Phytoestrogen have been used to treat menopause syndromes by replacing traditional estrogen. This experiment aimed to determine the effects of the phytoestrogen genistein on the contractile response of smooth muscle strips isolated from guinea pig gallbladder and its possible mechanism of action. METHODS: Guinea pigs were sacrificed to remove the whole gallbladder. Two or three smooth muscle strips were cut longitudinally. Each strip was suspended in a tissue chamber containing Krebs solution. After 2 hours of equilibration, contractile response indexes were recorded. Different concentrations of genistein were added to the chamber and the contractile responses were measured. Each antagonist was added 2 minutes before genistein to study possible mechanisms. The effect of genistein on calcium-dependent contraction curves and biphasic contraction in calcium-free Krebs solution were measured. RESULTS: Genistein decreased the resting tension dose-dependently, and reduced the mean contractile amplitude and frequency in gallbladder strips. Ranitidine partly inhibited the effect of genistein, but methylene blue, N(omega)-nitro-L-arginine, and propranolol hydrochloride did not influence this action. Genistein had no significant effects on calcium-dependent contraction. Genistein reduced the first contraction induced by acetylcholine chloride, but did not affect the second contraction caused by CaCl(2). CONCLUSIONS: Genistein relaxed smooth muscle isolated from the gallbladder of guinea pigs and this might contribute to the formation of gallstones. The inhibitory action might be related to H(2) receptors and the release of intracellular Ca(2+) from sarcoplasmic reticulum. Replacing traditional estrogen with phytoestrogen to treat menopause syndromes may increase the risk of gallstone formation.

EFFECT OF THE PHASE STRUCTURE EVOLUTION ON THE PROPERTIES OF FILMS FORMED FROM PBA/P(St-co-MMA) COMPOSITE LATEX

A group of heterogeneous latexes poly(butyl acrylate)/poly(styrene-co-methyl methacrylate)(PBA/P(St-co-MMA)) were prepared by a semi-continuous seeded emulsion polymerization process under monomer starved conditions.The glass transition temperature(T_g)and the mechanical properties of the film formed from the composite latex changed with the evolution of the particle morphology.A photon transmission method was used to monitor the phase structure evolution of films which were prepared from core-shell PBA/P(S...

Inactivation of Escherichia coil on Immobilized CuO/CoFe2O4-TiO2 Thin-Film under Simulated Sunlight Irradiation

Composite photocatalysts of CuO/CoFe2O4-TiO2 were successfully synthesized by a sol-gel method and fixed on ordinary tiles. The photosterilization of Escherichia coli was examined on CuO/CoFe2O4-TiO2 thin films under a xenon lamp irradiation. The film was characterized by XRD, and the morphology was observed by SEM. Disinfection data indicated that CuO/CoFe2O4-TiO2 composite photocatalysts have the much better photocatalytic activity than CuO/CoFe2O4 and TiO2. The optimized composition of the nanocomposites has been found to be CuO/CoFe2O4： mTio2=3：7, with loadings ranging from 790 to 1400 mg/m2. The photocatalytic inactivated rate of E. coli （105 CFU/mL） reached 98.4% under the xenon lamp of 150 W within 30 min.

Synthesizing Scheduled Robust Model Predictive Control with Target Tracking

Systems with large operating regions and non-zero state target tracking have limited the industrial application of robust model predictive control (RMPC) with synthetic action. To overcome the problem, this paper presents a novel formulation of synthesizing scheduled RMPC for linear time varying (LTV) systems. Off-line, we compute the matrix that transforms target output into steady state first. Then a set of stabilizing state feedback laws which are corresponding to a set of estimated regions of stability covering the desired operating region are provided. On-line, these control laws are implemented as a single scheduled state feedback model predictive control (MPC) which switches between the set of local controllers and achieve the desired target at last. Finally, the algorithm is illustrated with an example.

CALCULATION OF SOUND INSERTIONLOSS OF A BARRIER BY FRESNEL ZONE METHOD

In this paper formulas are presented to estimate the sound pressure amplitude at the observation point behind a half-infinite sound barrier, especially in the shadow region. The barrier may be a thin screen, or a wedge, or a wide barrier. These formulas are based on the Huygens-Fresnel principle of diffraction and on the concept of Fresnel half-period zone. By using these formulas a new method, Fresnel Zone Method, to calculate sound insertion loss of a barrier is obtained. The calculations agree well with the experimental results.