Development of synthetic surfactant and its protective effect on alveolar type II cell

（1）合成表面活性剂蛋白的开发。利用pET 80载体和人工合成的DNA，在大肠杆菌中表达了一种模拟表面活性蛋白C（Sp-C）的合成肽。然而，合成肽的产率极低。接下来，我们尝试将合成肽表达为使用pQE 40载体与DHPP蛋白融合的融合蛋白和使用pET 32 a与tluoredoxin融合的融合蛋白。然而，两种情况下的产率都很低。低产量被认为是因为合成肽对大肠杆菌的高毒性。因此，我们无法成功表达合成肽。（2）高碳酸血症的保护作用。高浓度CO2可抑制IL-1刺激的肺泡Ⅱ型细胞分泌TNF的增加。炎性细胞因子的mRNA水平没有升高。因此，高浓度的二氧化碳在转录后水平抑制TNF的释放。（3）烟酰胺对肺缺血再灌注损伤的影响。成年大鼠左肺缺血90 min后再灌注。给予烟酰胺的大鼠的动脉血氧分压为290±80（SD）mmHg，显著高于对照组大鼠（约100 mmHg）。烟酰胺可明显减轻肺缺血再灌注损伤。（4）肺表面活性物质损伤后肺扩张的分析。用表面活性物质与血清混合处理的未成熟新生兔的机械通气引起小肺泡塌陷和大肺泡过度扩张。然而，这种表面活性剂增加潮气量的程度与正常表面活性剂相同。正常潮气量并不一定意味着正常的表面活性物质功能，并可能导致忽视受损的表面活性物质功能。

(1)Development of a synthetic surfactant protein. A synthetic peptide mimicking surfactant protein-C (Sp-C) was expressed in E.coli, by using pET80 vector and synthetic DNA. However, the yield of synthetic peptide was extremely low. Next, we tried to express the synthetic peptide as fusion proteins fused with DHPP protein using pQE40 vector and with tluoredoxin using pET32a. However, the yields were low in both cases. The low yield is thought to be because of high toxicity of the synthetic peptide to E.coli. So, we could not succeed in expressing synthetic peptide.(2)Protective of effect of hypercapnia. High concentration of carbon dioxide (suppressed the increase of TNF released from alveolar type II cell stimulated by IL-1 under cell culture. The levels of mRNA for inflammatory cytokine were not elevated. So, high concentration of carbon dioxide inhibits TNF release at the post-transcription level.(3)Effect of nicotine amide of lung ischemia rperfuusion injury. The left lung of adult rats was reperfirsed after 90 min of ischemia. The arterial oxygen pressure of rats given nicotinamide was 290±80 (SD) mmHg and was significantly higher than that of the control rat (about 100 mmHg). Nicotine amide significantly reduced the lung ischemia reperfusion injury.(4)Analysis of the lung expansion after surfactant impairment. Mechanical ventilation of immature newborn rabbits treated with surfactant mixed with serum causes the collapse of small alveoli and the overexpansion of large alveoli. However, this surfactant increased the tidal volume to the same extent as normal surfactant. Normal tidal volume dose not necessarily mean normal surfactant function and may lead to overlooking impaired surfactant function.