• Tuberculosis and Respiratory Diseases
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• v.39 no.3
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• pp.242-247
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• 1992

Background: The ability to precisely measure specific mRNA levels by hybridization to complementary DNA probes is an important tool for analyzing the regulation of gene expression. Surfactant proteins have important roles in regulating surfactant metabolism as well as in determing its physical properties. Method: The complete coding regions for rat surfactant protein complementary DNA of surfactant protein B were subcloned into pGem 3Z or 4Z such that either antisense or sense transcripts were obtained by using SP 6 RNA polymerase. Surfactant protein B mRNA was measured by filter hybridization. Results: Equation of standard curve between counts per minute (Y) and surfactant protein B mRNA transcript input (X) was Y=2034.9 X+159.1. Correlation coefficient was 1.0. Couclusions: Filter hybridization assay is suited to situation when rapid, accurate quantitation of multiple samples is required.

• Tuberculosis and Respiratory Diseases
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• v.48 no.4
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• pp.513-521
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• 2000

Background : TNF may play an important role(central mediator) in the development of an acute respiratory distress syndrome. Since TNF induced lung injury in the acute respiratory distress syndrome and abnormalities in surfactant function have been described in acute respiratory distress syndrome, the authors investigated the effects of TNF on the regulation of surfactant protein A, B and C mRNA accumulation. Methods : The effects of TNF on gene expression of surfactant protein A, B, and C were analyzed using filter hybridization, 12 and 24 hours after intravenous injection of TNF in rats. Results : 1. The accumulation of SP-A mRNA in the TNF treated group (12 and 24 hours after TNF injection) was significantly decreased by 22.9% and 27.4%, respectively, compared to the control group (P<.025, P<.025). 2. The accumulation of SP-B mRNA in 24 hours after TNF treated group was significantly decreased by 20.5% compared to that of the control group(P<.01). 3. The accumulation of SP-C mRNA in 12 hours after TNF treated group was significantly decreased by 31% the compared to that of the control group(P<.01). Conclusions : These findings indicate the marked inhibitory effects of tumor necrosis factor on surfactant proteins expression in vivo. This finding. in turn, supports the idea of inhibitory effects of tumor necrosis factor on surfactant proteins expression as it relates to pathogenesis of acute respiratory distress syndrome.

• Tuberculosis and Respiratory Diseases
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• v.54 no.4
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• pp.439-448
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• 2003

Background : Surfactant protein B(SP-B) and surfactant protein C(SP-C) are important in accelerating surface spreading of surfactant phospholipid. The glucocorticoids accelerate the morphologic differentiation of epithelial cells into type II cells and increase the rate of phosphatidylcholine synthesis. The hydrophobic surfactant protein has been shown to be upregulated by glucocorticoids in vitro, however, its regulation in vivo is not well established. Methods : The authors investigated the effects of glucocorticoid on the accumulation of mRNA encoding SP-B and SP-C protein content of the lung. Adult rats were given different doses of subcutaneous dexamethasone and sacrificed at 24 hours and 1 week. SP-B and SP-C mRNA were measured by a filter hybridization method. Results : 1) The accumulation of SP-B mRNA at 24 hours after 0.2 mg/kg dexamethasone treatment was increased by 23.7%. 2) The accumulation of SP-B mRNA at 1 week after 2 mg/kg dexamethasone treatment was significantly increased by 96.6%(P<0.001). 3) The accumulation of SP-C mRNA at 24 hours after 0.2 mg/kg dexamethasone treatment was significantly increased by 42.7%(P<0.01). 4) The accumulation of SP-C mRNA at 1 week after 2 mg/kg dexamethasone treatment was significantly increased by 60.0% (P<0.01). Conclusion : The authors concluded that dexamethasone treatment in vivo resulted in increased levels of SP-B mRNA and SP-C mRNA. These results suggested that dexamethasone stimulates the synthesis of hydrophobic proteins associated with surfactant.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.369-379
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• 1998

Background: Platelet-activating factor(PAF) might play an important role in the development of acute respiratory distress syndrome. Since PAF induced lung injury is similar to changes of acute respiratory distress gyndrome, and abnormalities in surfactant function have been described in acute respiratory distress syndrome, the authors investigated the effects of PAF on the regulation of surfactant protein A, B and C mRNA accumulation Method: The effects of PAF on gene expression of surfactant protein A, B and C in 24 hours after intratracheal injection of PAF in rats. Surfactant protein A, B and C mRNAs were measured by filter hybridization. Results: The accumulation of SP-A mRNA in PAF treated group was significantly decreased by 37.1 % and 41.6%, respectively compared to the control group and the group treated with Lyso-PAF(p<0.025, p<0.01). The accumulation of SP-B mRNA in PAF treated group was decreased by 18.7% and 32.2 %, respectively compared to the control group and the group treated with Lyso-PAF but statistically not significant. The accumulation of SP-C mRNA in PAF treated group was significantly decreased by 30.7% and 38.5%, respectively compared to the control group and the group treated with Lyso-PAF(p<0.l, p<0.01). Conclusion: These findings represent a marked inhibitory effects of platelet-activating factor on surfactant proteins expression in vivo. This supports, in turn, 'platelet-activating factor might be related to pathogenesis of acute respiratory distress syndrome.

• Clinical and Experimental Pediatrics
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• v.62 no.5
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• pp.155-161
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• 2019

Following the first successful trial of surfactant replacement therapy for preterm infants with respiratory distress syndrome (RDS) by Fujiwara in 1980, several animal-derived natural surfactants and synthetic surfactants have been developed. Synthetic surfactants were designed to overcome limitations of natural surfactants such as cost, immune reactions, and infections elicited by animal proteins contained in natural surfactants. However, first-generation synthetic surfactants that are protein-free have failed to prove their superiority over natural surfactants because they lack surfactant protein (SP). Lucinactant, a second-generation synthetic surfactant containing the SP-B analog, was better or at least as effective as the natural surfactant, suggesting that lucinactant could act an alternative to natural surfactants. Lucinactant was approved by the U. S. Food and Drug Administration in March 2012 as the fifth surfactant to treat neonatal RDS. CHF5633, a second-generation synthetic surfactant containing SP-B and SP-C analogs, was effective and safe in a human multicenter cohort study for preterm infants. Many comparative studies of natural surfactants used worldwide have reported different efficacies for different preparations. However, these differences are believed to due to site variations, not actual differences. The more important thing than the composition of the surfactant in improving outcome is the timing and mode of administration of the surfactant. Novel synthetic surfactants containing synthetic phospholipid incorporated with SP-B and SP-C analogs will potentially represent alternatives to natural surfactants in the future, while improvement of treatment modalities with less-invasive or noninvasive methods of surfactant administration will be the most important task to be resolved.

• Tuberculosis and Respiratory Diseases
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• v.38 no.3
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• pp.228-235
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• 1991

Pulmonary surfactant is a lipoprotein complex composed primarily of phospholipid and lungspecific apoproteins that reduces surface tension in the alveolus and maintains alveolar stability at low lung volume. Three families of lung-specific apoproteins have been described: SP-A, a glycoprotein with a reduced molecular weight of 28~36 KDa. SP-B a hydrophobic protein with a nonreduced molecular weight of 18 KDa, and SP-C a hydrophobic protein with a non-reduced molecular weight of 5~8 KDa. Surfactant proteins have important roles in regulating surfactant metabolism as well as in determining its physical properties. The synthesis of the active surfactant peptides appears to be modulated by system with considerable complexity, including numerous levels of regulation such as cell-specific, hormonal and developmental controls. Endotoxin appears to alter surfactant protein mRNAs differentially. It is hoped that the elucidation of the factors controlling the synthesis and metabolism of the surfactant proteins will aid in understanding the pathogenesis of hyaline membrane disease and offer new avenues for the therapy and diagnosis of ther pulmonary disorders as well.

• Tuberculosis and Respiratory Diseases
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• v.54 no.5
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• pp.510-521
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• 2003

Background : The surfactant specific proteins, SP-B and SP-C are believed to be important regulators of the surfactant function and homeostasis. Since acute respiratory distress syndrome(ARDS) is usually viewed as the functional and morphological expression of a similar underlying lung injury caused by a variety of insults, and since abnormalities in the surfactant function have been described in ARDS, the authors investigated the different effects of endotoxin and thiourea on the accumulation of mRNA encoding SP-B and SP-C. Methods : Sprague-Dawley rats were given 5 mg/kg of an intraperitoneal endotoxin from Salmonella enteritidis and 3.5 mg/kg intraperitoneal thiourea and were sacrificed at different time periods. Results : 1. The SP-B mRNA levels 6 and 24 hours after the 5 mg/kg endotoxin treatment was significantly reduced by 26.1% and 50%, respectively(P<0.01, P<0.001). 2. The SP-B mRNA levels 24 hours after the 3.5 mg/kg thiourea treatment was reduced by 9.8% and 12.5%, respectively. 3. The SP-C mRNA levels 6 and 24 hours after the 5 mg/kg endotoxin treatment was significantly reduced by 38.7% and 53.6%, respectively(P<0.01, P<0.001). 4. The SP-C mRNA level 6 hours after the 3.5 mg/kg thiourea treatment was reduced by 22.8%(P<0.05). Conclusion : These results indicate that the differential regulation of the hydrophobic surfactant proteins in vivo is evident, and suggest that the hydrophobic surfactant proteins might be differentially regulated during lung injury at different time periods without altering the lung wet to dry ratios. The mechanism of these alternations at the different time periods and the different kinds of etiology remain to be determined.

• Tuberculosis and Respiratory Diseases
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• v.52 no.4
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• pp.395-404
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• 2002

Background : Surfactant protein A (SP-A) is important for regulating surfactant secretion, synthesis and recycling. However, It's regulation in vivo is unclear. SP-A has important roles in regulating surfactant metabolism as well as determining its physical properties. Glucocorticoid accelerates the morphologic differentiation of epithelial cells into type II cells and increase the rate of phosphatidylcholine synthesis. Methods : The authors investigated the effects of glucocorticoid on the accumulation of mRNA encoding SP-A and SP-A protein content. Adult rats were given various doses of subcutaneous dexamethasone and sacrificed after 24 hours and one week. SP-A mRNA was measured using a filter hybridization method. The lung SP-A protein content was determined using a double sandwich ELISA assay with polyclonal antiserum raised in rabbits against purified rat SP-A. Results : 1) The accumulation of SP-A mRNA in the dexamethasone treated group 24 hours after 0.2 mg/kg dexamethasone treatment was increased 38.8% compared to the control group. 2) The accumulation of SP-A mRNA in the dexamethasone treated group 1 week after 2 mg/kg dexamethasone treatment was 49.7% higher than the control group(P<0.01). 3) The total lung SP-A level was not altered after 24 hours by the 0.2mg/kg treatment. The total lung SP-A content one week after 2mg/kg dexamethasone administration was 373.7% higher than the control group(P<0.005). Conclusion : Dexamethasone treatment results in an increase in the SP-A mRNA and SP-A protein levels, suggesting that the pretranslational events in vivo may in part contribute to this process.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.5
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• pp.617-628
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• 1998

In order to understand the pathogenetic mechanism of adult respiratory distress syndrome (ARDS), the role of phospholipase A2 (PLA2) in association with oxidative stress was investigated in rats. $Interleukin-1{\alpha}\;(IL-1,\;50\;{\mu}g/rat)$ was used to induce acute lung injury by neutrophilic respiratory burst. Five hours after IL-1 insufflation into trachea, microvascular integrity was disrupted, and protein leakage into the alveolar lumen was followed. An infiltration of neutrophils was clearly observed after IL-1 treatment. It was the origin of the generation of oxygen radicals causing oxidative stress in the lung. IL-1 increased tumor necrosis factor (TNF) and cytokine-induced neutrophil chemoattractant (CINC) in the bronchoalveolar lavage fluid, but mepacrine, a PLA2 inhibitor, did not change the levels of these cytokines. Although IL-1 increased PLA2 activity time-dependently, mepacrine inhibited the activity almost completely. Activation of PLA2 elevated leukotriene C4 and B4 (LTC4 and LTB4), and 6-keto-prostaglandin $F2{\alpha}\;(6-keto-PGF2{\alpha})$ was consumed completely by respiratory burst induced by IL-1. Mepacrine did not alter these changes in the contents of lipid mediators. To estimate the functional changes of alveolar barrier during the oxidative stress, quantitative changes of pulmonary surfactant, activity of gamma glutamyltransferase (GGT), and ultrastructural changes were examined. IL-1 increased the level of phospholipid in the bronchoalveolar lavage (BAL) fluid, which seemed to be caused by abnormal, pathological release of lamellar bodies into the alveolar lumen. Mepacrine recovered the amount of surfactant up to control level. IL-1 decreased GGT activity, while mepacrine restored it. In ultrastructural study, when treated with IL-1, marked necroses of endothelial cells and type II pneumocytes were observed, while mepacrine inhibited these pathological changes. In histochemical electron microscopy, increased generation of oxidants was identified around neutrophils and in the cytoplasm of type II pneumocytes. Mepacrine reduced the generation of oxidants in the tissue produced by neutrophilic respiratory burst. In immunoelectron microscopic study, PLA2 was identified in the cytoplasm of the type II pneumocytes after IL-1 treatment, but mepacrine diminished PLA2 particles in the cytoplasm of the type II pneumocyte. Based on these experimental results, it is suggested that PLA2 plays a pivotal role in inducing acute lung injury mediated by IL-1 through the oxidative stress by neutrophils. By causing endothelial damage, functional changes of pulmonary surfactant and alveolar type I pneumocyte, oxidative stress disrupts microvascular integrity and alveolar barrier.