Experimental Study On The Mechanism Of Acute Lung Injury After Multiple Fracture

Since the 70s of the 20th century, though the operation skills and treatment support technology of the multiple fracture has improved a lot, but the later stage mortality of these severe trauma has not obviously reduced. Its main reason is Multiple organ dysfunction syndrome (MODS). Studies have indicated that multiple fracture and following occurred MODS have a certain relationship, and the"Two-hit theory"was proposed in the 1990s by Moore .The concept presumed that multiple fracture or shock etc. as the first hit makes the organism in medium-degree state of Systemic inflammatory response syndrome (SIRS), thereafter serious infection, shock, etc. as the second hit, have already enlarged excessive SIRS taken place in the inflammation state of the existence, thus demonstrate as Acute lung injury (ALI) and its serious modality - Acute respiratory distress syndrome ( ARDS ) firstly before occur to MODS stage. Among these factors, Gram-negative bacteria infection occupy important status in clinic. The Lipopolysaccharide (LPS), main composition of endotoxin of its cell wall can cause many kinds of organism damage.When ALI occurred, alveolar epithelial cells appear not only structural and functional injury, but also severe apoptosis. So the recovery of alveolar epithelium in ALI involves in repairing of cellular structure and function, also involves in regenerating of alveolar epithelial cells. Many cytokines yielded by mesenchymal cells can act as signal molecule to regulate epithelial proliferation and differentiation. Among these cytokines, Keratinocyte growth factor (KGF) is the one of the most important factors. KGF is not only the mitogen of epithelial cells, but also the cytokine, which can enhance regeneration and sodium-water transport of alveolar epithelial cells. KGF can only conjugate KGF receptor (KGFR), which expressed by epithelial cells, and bring into full play biological functions. These biological functions include acceleration of Na+-K+-ATP enzyme expression and sodium passage quantities on membrane; enhancement of surfactant which synthesis and excretion by...