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141.
142.
Luiz-Ferreira A Almeida AC Cola M Barbastefano V Almeida AB Batista LM Farias-Silva E Pellizzon CH Hiruma-Lima CA Santos LC Vilegas W Brito AR 《Molecules (Basel, Switzerland)》2010,15(10):7153-7166
Leaves and bark infusions Anacardium humile St. Hil. (Anacardiaceae), known as in Brazil as "cajuzinho do cerrado", have been used in folk medicine as an alternative treatment for ulcers and gastritis. This study evaluated the gastroprotective activity of an ethyl acetate extract of the leaves of A. humile (AcF) and the mechanism involved in this gastroprotection. Pretreatment concentrations (50, 100, 200 mg x kg?1) were administered by gavage. Following a 60 min. period, all the rats were orally administered 1 mL of absolute ethanol. One hour after the administration of ethanol, all groups were sacrificed, and the gastric ulcer index was calculated. Prostaglandin PGE? concentration, gastric adherent mucous, and the participation of nitric oxide (NO) and sulfhydryl compounds in the gastroprotection process were also analyzed using the most effective tested dose (50 mg x kg?1). A histological study of the glandular stomach for the evaluation of the epithelial damage and mucus content was also performed. AcF significantly reduced the gastric damage produced by ethanol. This effect was statistically significant for the 50 mg x kg?1 group compared to control. Also, it significantly increased the PGE? (by 10-fold) and mucous production, while pretreatment with NG-nitro-L-arginine methyl ester (L-NAME) or N-ethylmaleimide (NEM) completely abolished the gastroprotection. AcF has a protective effect against ethanol, and this effect, might be due to the augmentation of the protective mechanisms of mucosa. 相似文献
143.
Octavio Augusto Novaro María del Alba Pacheco-Blas Juan Horacio Pacheco-Sánchez 《Theoretical chemistry accounts》2010,126(3-4):109-116
A study of nonadiabatic transitions through avoided crossings between two potential energy curves, associated to the approach of a mercury atom to an organic gas molecule (silane or germane) is presented. We study the Si–H and Ge–H bond breaking in the molecules SiH4 and GeH4, which are an important subject in the production of hydrogenated amorphous thin films. We here emphasize the importance of the excited states, the avoided crossings generated during the molecule–metal approach and the nonadiabatic transition probabilities. We have developed a model to extend the Landau–Zener theory utilizing the angle instead of the distance as the main parameter of the reaction, which is particularly adapted for tetrahedral molecules (as silane and germane). The activation process of these molecules requires several stages; first, we solve the Schrödinger equation (within the Born-Oppenheimer approximation) for the metal–molecule system during interaction. We always take into account all those states that can play a role in the reaction, even those that because of their energetic separation from the ground state are forgotten by other groups. The calculations begin at a LCAO-MO approximation and thenceforth variational and perturbative CI including of the order of a million determinants are carried out. Usually, some states of the metal repel the gas molecule and others attract it. This produces a series of avoided crossings among the curves, demanding that the nonadiabatic transition probabilities are obtained. This is the ultimate goal of the present study. 相似文献
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147.
R. Estrada R. Rodríguez V. M. Casta?o 《Applied Physics A: Materials Science & Processing》2010,99(4):723-728
A new kind of synthetic membrane was designed with the capacity to adjust the pore diameter in a wide range of sizes (from
0.8 to 22.3 microns) just by changing the pH of the aqueous medium where it is immersed; in this way it is possible to control
externally the pore size of the membrane. A non-linear mathematical model, based on the overlap of the electrical double layers
of charged particles, was developed to explain the oscillatory behavior of the pore size when the pH was varied. This model
fits correctly this oscillatory behavior. Scanning electron microscope images were obtained in low-vacuum conditions to reduce,
as much as possible, possible changes in the external conditions after the immersion in water. 相似文献
148.
Ana Lí a Durá n Ricardo Estrada 《Proceedings of the American Mathematical Society》1999,127(6):1745-1751
We identify a class of functions for which an extension of the well known integral test holds, namely, the series is Cesàro summable if and only if the integral is. We also give the corresponding multidimensional results.
149.
Barreca ML Gitto R Quartarone S De Luca L De Sarro G Chimirri A 《Journal of chemical information and computer sciences》2003,43(2):651-655
A three-dimensional pharmacophore model for the binding of noncompetitive AMPA receptor antagonists was developed in order to map common structural features of highly active compounds. This hypothesis, which consists of two hydrophobic regions, one hydrogen bond acceptor and one aromatic region, was successfully used as framework for the design of a new class of allosteric modulators containing a tetrahydroisoquinoline skeleton and for in silico screening. The promising biological results suggested that the identified molecules might be useful "lead compounds" for future drug development. 相似文献
150.
Neurotoxicities of a series of solvents in rats and mice have been modeled by means of the TOPS-MODE approach. Two quantitative structure-toxicity relationship (QSTR) models were obtained explaining more than 80% of the variance in the experimental values of neurotoxicity of 45 solvents. Only one compound was detected as statistical outlier for these models. In contrast, previous models explained less than 60% of the variance in this property for 44 solvents. Finally, the contributions to neurotoxicity in rats and mice for a series of structural fragments were found. Structural characteristics of chlorinated fragments responsible for their different neurotoxicities were analyzed. The differences in neurotoxic behavior of some fragments in rats and mice were also analyzed, which could give insights on the toxicological mechanism of action of solvents studied. 相似文献