Ana M. de Paula

Soluble Guanylyl Cyclase (sGC) Degradation and Impairment of Nitric Oxide-Mediated Responses in Urethra from Obese Mice: Reversal by the sGC Activator BAY 60-2770

Obesity has emerged as a major contributing risk factor for overactive bladder (OAB), but no study examined urethral smooth muscle (USM) dysfunction as a predisposing factor to obesity-induced OAB. This study investigated the USM relaxant machinery in obese mice and whether soluble guanylyl cyclase (sGC) activation with BAY 60-2770 [acid 4-({(4-carboxybutyl) [2-(5-fluoro-2-{[4-(trifluoromethyl) biphenyl-4-yl] methoxy} phenyl) ethyl] amino} methyl) benzoic] rescues the urethral reactivity through improvement of sGC-cGMP (cyclic guanosine monophosphate) signaling. Male C57BL/6 mice were fed for 12 weeks with a high-fat diet to induce obesity. Separate groups of animals were treated with BAY 60-2770 (1 mg/kg per day for 2 weeks). Functional assays and measurements of cGMP, reactive-oxygen species (ROS), and sGC protein expression in USM were determined. USM relaxations induced by NO (acidified sodium nitrite), NO donors (S-nitrosoglutathione and glyceryl trinitrate), and BAY 41-2272 [5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine] (sGC stimulator) were markedly reduced in obese compared with lean mice. In contrast, USM relaxations induced by BAY 60-2770 (sGC activator) were 43% greater in obese mice (P < 0.05), which was accompanied by increases in cGMP levels. Oxidation of sGC with ODQ [1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one] (10 μM) potentiated BAY 60-2770-induced USM responses in the lean group. Long-term oral BAY 60-2770 administration fully prevented the impairment of USM relaxations in obese mice. Reactive-oxygen species (ROS) production was enhanced, but protein expression of β1 second guanylate cyclase subunit was reduced in USM from obese mice, both of which were restored by BAY 60-2770 treatment. In conclusion, impaired USM relaxation in obese mice is associated with ROS generation and down-regulation of sGC-cGMP signaling. Prevention of sGC degradation by BAY 60-2770 ameliorates the impairment of urethral relaxations in obese mice.

Carrier capture processes in semiconductor superlattices due to emission of confined phonons

Carrier capture times due to the emission of confined longitudinal optical phonons via electron–phonon (Frohlich) interaction are calculated for GaAs‐AlxGa1−xAs and In0.47Ga0.53As‐InP superlattices. A dielectric continuum model is used to describe the confined phonon modes and we use a Kronig–Penney type calculation for the electron envelope functions. We compare our results with capture times measured by several optical techniques and we discuss the importance of a knowledge of the carrier excitation details in order to obtain an appropriate interpretation of the experimental results. We show that electrons excited into confined states with a large kinetic energy strongly influence the overall capture times.

Ultrafast processes in semiconductor doped glasses

We review studies of resonant and nonresonant ultrafast optical processes in semiconductor doped glasses, made at the University of Campinas. First we discuss measurements done in CdTe quantum-dots in glass, excited resonantly. In this case we observe a fast recombination, that depends on the size of the quantum-dot. For the smallest dots, with 3.2 nm average radius, the recovery time constant was found to be 360 fs. Then we describe the observation of the Optical Stark shift in CdSxSe1−x semiconductor-doped glass (SDG) excited under nonresonant below gap condition and probed with femtosecond optical pulses. An ultrafast and pure light-induced shift of the band edge is observed. For a pump intensity of 3 GW/cm2 the band shifts by 11 meV. The response of the shift tracks the profile of the pumping pulse.

Γ to Xz electron transfer times in type‐II superlattices due to emission of confined phonons

We calculate the Γ→Xz electron transfer times due to the emission of confined longitudinal optical phonons in type‐II GaAs‐AlAs and AlGaAs‐AlAs superlattices. A dielectric continuum model is employed to describe the electron‐confined‐phonon interaction and the electron envelope wave functions are obtained from a Kronig–Penney model. The calculated transfer times compare within order of magnitude, or better, with available experimental results and we obtain a good qualitative description of the transfer time dependence on the layer thicknesses.

Estudo das propriedades ópticas em vidros 0,3La2S3-0,7Ga2S 3

In this work we describe the synthesis and characterization of chalcogenide glass (0.3La2S3-0.7Ga2S 3) with low phonons frequencies. Several properties were measured like Sellmeier parameters, linear refractive index dispersion and material dispersion. Samples with the composition above were doped with Dy2S3. The absorption and emission characteristics were measured by electronic spectroscopy and fluorescence spectrum respectively. Raman and infrared spectroscopy shows that these glasses present low phonons frequencies and strucuture composed by GaS4 tetrahedrals. The Lines model was used for calculate the coefficients values of the non linear refractive index.