This study investigates the gastroprotective effects of hecogenin, a steroid saponin isolated from Agave sisalana, on experimental models of gastric ulcer. Male Swiss mice were used in the models of ethanol- and indometacin-induced gastric ulcer. To clarify the hecogenin mechanism of action, the roles of nitric oxide (NO), sulfhydryls (GSH), K⁺(ATP) channels and prostaglandins were also investigated, and measurements of lipid peroxidation (TBARS assay) and nitrite levels in the stomach of hecogenin-treated and untreated animals were performed. Furthermore, the effects of hecogenin on myeloperoxidase (MPO) release from human neutrophils were assessed in vitro. Our results showed that hecogenin (3.1, 7.5, 15, 30, 60 and 90 mg/kg, p.o.) acutely administered, before ethanol or indomethacin, exhibited a potent gastroprotective effect. Although the pretreatments with L-NAME, an iNOS inhibitor, and capsazepine, a TRPV1 receptor agonist, were not able to reverse the hecogenin effect, this was reversed by glibenclamide, a K⁺(ATP) blocker, and indomethacin in the model of ethanol-induced gastric lesions. The hecogenin pretreatment normalized GSH levels and significantly reduced lipid peroxidation and nitrite levels in the stomach, as evaluated by the ethanol-induced gastric lesion model. The drug alone increased COX-2 expression and this effect was further enhanced in the presence of ethanol. It also decreased MPO release and significantly protected the gastric mucosa. In conclusion, we showed that hecogenin presents a significant gastroprotective effect that seems to be mediated by K⁺(ATP) channels opening and the COX-2/PG pathway. In addition, its antioxidant and anti-inflammatory properties may play a role in the gastroprotective drug effect.
Com base principalmente na teoria tensiva desenvolvida por Claude Zilberberg, este artigo tem como principal meta averiguar quais procedimentos cinematográficos são adotados no filme Pulp Fiction para modular os efeitos de sentido causados pela violência, a fim de examinar os modos como extensidade e intensidade se articulam na construção do espaço tensivo do enunciado fílmico e como isso repercute na experiência estética do enunciatário. Inicialmente, percebe-se que a violência se insere em um regime fundado na regularidade, de forma que as variações intensivas são controladas pela dimensão da extensidade, dificilmente havendo uma saturação de intensidade e, portanto, jamais sendo atribuído à violência um estatuto de acontecimento. Valendo-se, assim, de alguns mecanismos fílmicos, que pretendemos descrever, Tarantino parece investir em andamentos, tonicidades, temporalidades e espacialidades adequados para o exercício da inteligibilidade, isto é, lança mão de procedimentos que promovem mais a apreensão cognitiva das cenas de violência do que a sua experiência afetiva, o que permitiria ao enunciatário fruir a obra preponderantemente na dimensão racional. Dessa maneira, a partir de estudos semióticos bastante recentes e, a nosso ver, extremamente adequados aos nossos propósitos, intencionamos ampliar o campo de discussão acerca de um aspecto muito peculiar do trabalho de Quentin Tarantino e lançar luz sobre questões que podem – e devem – ser desenvolvidas em pesquisas futuras.
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