AIM： To investigate the tight junction protein expressions of intestinal mucosa in an experimental model of cardiopulmonary bypass （CPB） in rats. METHODS： Thirty anesthetized rats were randomly divided into two gr...AIM： To investigate the tight junction protein expressions of intestinal mucosa in an experimental model of cardiopulmonary bypass （CPB） in rats. METHODS： Thirty anesthetized rats were randomly divided into two groups： Group S （n = 10） served as sham operation and group C （n = 20） served as CPB which underwent CPB for 1 h. Expression of occludin and zonula occludens-1 （ZO-1） were determined by Western blotting and immunotochemistry, respectively. Plasma levels of diamine oxidase （DAO） and d-lactate were determined using an enzymatic spectrophotometry. RESULTS： Immunohistochemical localization of occludin and ZO-1 showed disruption of the tight junctions in enterocytes lining villi at the end of CPB and 2 h after CPB. The intensities of the occludin and ZO-i at the end of CPB were lower than those of control group （76.4% ± 22.5% vs 96.5% ± 28.5% and 62.4% ± 10.1% vs 85.5% ±25.6%, P 〈 0.05） and were further lower at 2 h after CPB （50.5% ± 10.5% and 45.3% ± 9.5%, P 〈 0.05）. Plasma d-lactate and DAO levels increased significantly （8.688 ± 0.704 vs 5.745 ± 0.364 and 0.898 ± 0.062 vs 0.562 ± 0.035, P 〈 0.05） at the end of CPB compared with control group and were significantly higher at 2 h after CPB than those at the end of CPB （9.377 ± 0.769 and 1.038 ± 0.252, P 〈 0.05）. There were significant negative correlations between occludin or ZO-1 expression and DAO （r^2 = 0.5629,r^2 = 0.5424, P 〈 0.05） or d-lactate levels （r^2 = 0.6512,r^2 = 0.7073, P 〈 0.05） both at the end of CPB and 2 h after CPB. CONCLUSION： CPB markedly down-regulates the expression of occludin and ZO-1 proteins in intestinal mucosa of rats. The close correlation between expression of tight junctions （TJs） and plasma levels of DAO or d-lactate supports the hypothesis that intestinal permeability increases during and after CPB because of decreases in the expressions of TJs.展开更多
In this paper, a circular three-layer flow model is proposed to study mucus transport in the airways due to air motion caused by mild forced expiration or mild coughing. Mucus is represented by four-parameter viscoela...In this paper, a circular three-layer flow model is proposed to study mucus transport in the airways due to air motion caused by mild forced expiration or mild coughing. Mucus is represented by four-parameter viscoelastic fluid, a combination of Maxwell and Voigt elements, whereas air and serous fluid are taken as Newtonian fluids （incompressible）. The pressure gradient generated in the fluid layers is assumed to be given by a time- dependent function representing mild forced expiration or mild cough in the airways causing laminar flow. The effect of slip velocity at the mucus-serous interface caused by the presence of surfactant and at the top surface caused by immotile cilia are Mso taken into account. The roles of rheological properties of mucus on its transport are studied. The effect of serous fluid and its viscosity on mucus transport is also considered.展开更多
文摘AIM： To investigate the tight junction protein expressions of intestinal mucosa in an experimental model of cardiopulmonary bypass （CPB） in rats. METHODS： Thirty anesthetized rats were randomly divided into two groups： Group S （n = 10） served as sham operation and group C （n = 20） served as CPB which underwent CPB for 1 h. Expression of occludin and zonula occludens-1 （ZO-1） were determined by Western blotting and immunotochemistry, respectively. Plasma levels of diamine oxidase （DAO） and d-lactate were determined using an enzymatic spectrophotometry. RESULTS： Immunohistochemical localization of occludin and ZO-1 showed disruption of the tight junctions in enterocytes lining villi at the end of CPB and 2 h after CPB. The intensities of the occludin and ZO-i at the end of CPB were lower than those of control group （76.4% ± 22.5% vs 96.5% ± 28.5% and 62.4% ± 10.1% vs 85.5% ±25.6%, P 〈 0.05） and were further lower at 2 h after CPB （50.5% ± 10.5% and 45.3% ± 9.5%, P 〈 0.05）. Plasma d-lactate and DAO levels increased significantly （8.688 ± 0.704 vs 5.745 ± 0.364 and 0.898 ± 0.062 vs 0.562 ± 0.035, P 〈 0.05） at the end of CPB compared with control group and were significantly higher at 2 h after CPB than those at the end of CPB （9.377 ± 0.769 and 1.038 ± 0.252, P 〈 0.05）. There were significant negative correlations between occludin or ZO-1 expression and DAO （r^2 = 0.5629,r^2 = 0.5424, P 〈 0.05） or d-lactate levels （r^2 = 0.6512,r^2 = 0.7073, P 〈 0.05） both at the end of CPB and 2 h after CPB. CONCLUSION： CPB markedly down-regulates the expression of occludin and ZO-1 proteins in intestinal mucosa of rats. The close correlation between expression of tight junctions （TJs） and plasma levels of DAO or d-lactate supports the hypothesis that intestinal permeability increases during and after CPB because of decreases in the expressions of TJs.
文摘In this paper, a circular three-layer flow model is proposed to study mucus transport in the airways due to air motion caused by mild forced expiration or mild coughing. Mucus is represented by four-parameter viscoelastic fluid, a combination of Maxwell and Voigt elements, whereas air and serous fluid are taken as Newtonian fluids （incompressible）. The pressure gradient generated in the fluid layers is assumed to be given by a time- dependent function representing mild forced expiration or mild cough in the airways causing laminar flow. The effect of slip velocity at the mucus-serous interface caused by the presence of surfactant and at the top surface caused by immotile cilia are Mso taken into account. The roles of rheological properties of mucus on its transport are studied. The effect of serous fluid and its viscosity on mucus transport is also considered.
