Background: Results from experimental and clinical studies have shown that mechanical ventilation or/and hyperoxia may aggravate a pre-existing lung injury or even cause lung injury in healthy lungs by affecting the e...Background: Results from experimental and clinical studies have shown that mechanical ventilation or/and hyperoxia may aggravate a pre-existing lung injury or even cause lung injury in healthy lungs by affecting the expression of MMP-9, but the MMP-9 effects are controversial. How are MMP-9 regulated when multicausative factors of injury such as different FiO2, PIP, and respiratory time (RT) impose simultaneously on lungs? Methods: Newborn New Zealand white rabbits were randomly allocated to an unventilated air control group or to one of the 2 × 3 × 3 ventilation strategies by using a factorial design, with different FiO2, PIP, and RT. Then, lung wet-to-dry ratio (W/D), lung histopathology scores, transmission electron microscope, and cells in BALF were analyzed in these different groups. MMP-9 levels were studied by immunohistochemistry and ELISA. Results: MMP-9 levels were significantly different among 3 PIP ventilation regimes (F = 7.215) and MPIP group was the highest among 3 PIP groups. The lung histopathology score in 100% oxygen was significantly higher than in 45% oxygen group (F = 9.037) and MPIP group was the lowest among 3 PIP groups (F = 57.515) and RT 6 h was more serious than RT 1 h. MMP-9 positively correlated with monocytes, but negatively correlated with neutrophils and lung injury histopathology scores. Conclusions: Different PIP and FiO2 exert simultaneously on newborn lung in newborn rabbits ventilation, only mechanical stretch stimulation affects MMP-9 synthesis. Advisable mechanical stretch can promote MMP-9 expression and has protective role in lung in VILI. HPIP causes barotraumas and LPIP induces atelectrauma.展开更多
In this paper,we formulate an age-structured HIV model,in which the influence of humoral immunity and the infection age of the infected cells are considered.The model is governed by three ordinary differential equatio...In this paper,we formulate an age-structured HIV model,in which the influence of humoral immunity and the infection age of the infected cells are considered.The model is governed by three ordinary differential equations and two first-ordered partial differential equations and admits three equilibria:disease-free,immune-inactivated and immune-activated equilibria.We introduce two important thresholds:the basic reproduction number R〇and immune-activated reproduction number R\and further show the global stability of above three equilibria in terms of R〇and Ri,respectively.The numerical simulations are presented to illustrate our results.展开更多
文摘Background: Results from experimental and clinical studies have shown that mechanical ventilation or/and hyperoxia may aggravate a pre-existing lung injury or even cause lung injury in healthy lungs by affecting the expression of MMP-9, but the MMP-9 effects are controversial. How are MMP-9 regulated when multicausative factors of injury such as different FiO2, PIP, and respiratory time (RT) impose simultaneously on lungs? Methods: Newborn New Zealand white rabbits were randomly allocated to an unventilated air control group or to one of the 2 × 3 × 3 ventilation strategies by using a factorial design, with different FiO2, PIP, and RT. Then, lung wet-to-dry ratio (W/D), lung histopathology scores, transmission electron microscope, and cells in BALF were analyzed in these different groups. MMP-9 levels were studied by immunohistochemistry and ELISA. Results: MMP-9 levels were significantly different among 3 PIP ventilation regimes (F = 7.215) and MPIP group was the highest among 3 PIP groups. The lung histopathology score in 100% oxygen was significantly higher than in 45% oxygen group (F = 9.037) and MPIP group was the lowest among 3 PIP groups (F = 57.515) and RT 6 h was more serious than RT 1 h. MMP-9 positively correlated with monocytes, but negatively correlated with neutrophils and lung injury histopathology scores. Conclusions: Different PIP and FiO2 exert simultaneously on newborn lung in newborn rabbits ventilation, only mechanical stretch stimulation affects MMP-9 synthesis. Advisable mechanical stretch can promote MMP-9 expression and has protective role in lung in VILI. HPIP causes barotraumas and LPIP induces atelectrauma.
基金supported in part by Guangdong Natural Science Foundation(Nos.2016A030313426,2020A1515010445).
文摘In this paper,we formulate an age-structured HIV model,in which the influence of humoral immunity and the infection age of the infected cells are considered.The model is governed by three ordinary differential equations and two first-ordered partial differential equations and admits three equilibria:disease-free,immune-inactivated and immune-activated equilibria.We introduce two important thresholds:the basic reproduction number R〇and immune-activated reproduction number R\and further show the global stability of above three equilibria in terms of R〇and Ri,respectively.The numerical simulations are presented to illustrate our results.
