0.05). However, the MDA level in the experimental group was higher than that of the control on day 3 [(55.92?5.53)nmol/mg prot vs (22.52?4.36)nmol/mg prot, P

Objective To investigate the changes of epithelial sodium channel(ENaC) expression and sodium and water transport function in the neonatal rat pulmonary edema induced by hyperoxia.Methods The neonatal rats were randomly divided into the hyperoxia group and the control group.After 1,3,5 and 7 d hyperoxia exposure,the lung tissues were collected to measure the wet-to-dry weight ratio and the expression of α-,β-and γ-ENaC subunits were detected by western blot analysis.Alveolar fluid clearance (AFC) and amiloride-sensitive AFC were measured after 5 d to reveal the effect of hyperoxia on the activity of ENaC.Results The lung water contents significantly increased in the hyperoxia group indicating that pulmonary edemahappened(3 d:(6.37 ±0.64) vs (5.56±0.15),t=3.46,P＜0.01;5 d:(5.86 +0.52) vs (5.11±0.21),t=-3.82,P ＜0.01;7 d:(5.56±0.45) vs (4.80±0.09),t =-4.72,P ＜0.01).AFC increased significantly,but no significant difference was found in amiloride-insensitive AFC between the two groups which indicate that amiloride-sensitive AFC increased significantly (AFC:(20.32 ± 3.33) ％ vs (12.97 ± 2.46) ％,t =-6.16,P ＜ 0.01 ; amiloride-insensitive AFC:(10.42 ± 3.44) ％ vs (8.67 ± 3.13) ％,t =-1.30 P =0.21).The expression of α-,β-and γ-ENaC did not reduced after hyperoxia exposure compared with the control group.Conclusion Although bronchopulmonary dysplasia of early pulmonary edema induced by hyperoxia,dysfunctional transport of Na + may not be a key factor involved in pulmonary edema at the early stage of bronchopulmonary dysplasia.

Objective To investigate the expression and significance of Smad4 and Smad7 in newborn rats with hyperoxia-induced chronic lung disease(CLD).Methods Sixty-four newborn Wistar rats 12 h after birth were divided into high-oxygen group (n =32) and air group (n =32,control group) by random number table method.The high-oxygen group was placed in the oxygen glass tank with continuous infusion of oxygen.And 1,3,7,14 d after experiment,tracheal separated,the chest opened to expose heart and lung,slices were Masson staining,undergo dynamic observation of the pulmonary pathological changes under light microscope.Lung fibrosis score was carried out to determine the degree of pulmonary fibrosis,and immunohistochemical technique was used to detect Smad4 and Smad7 protein expression in lung tissue.The expression levels of Smad4 and Smad7 protein in lung tissue were detected with Western blot.Results Compared with the air group,there was statistically significant difference in pulmonary fibrosis score on day 7 (2.67 ± 0.21 vs 0.58 ± 0.17) and day 14 (4.48 ± 0.24 vs 0.63 ± 0.13) in high-oxygen group (P ＜ 0.05) ; Smad4 and Smad7 was main in visible lung epithelial cells and interstitial fibroblasts.Smad4 expression in the high-oxygen group gradually enhanced,compared with the air group (P ＜ 0.05) on day 7 (122.35 ± 10.3 vs 140.08 ±7.77) and day 14(129.7 ± 7.33 vs 144.99 ± 6.49).Smad7 expression in the high-oxygen group first increased and then decreased,expression in the high-oxygen group increased on day 7 (122.35 ± 10.29 vs 130.56 ±9.8),and compared decreased with the air group(P ＜0.05) on day 14(132.16 ±4.38 vs 126.22 ±6.49).Conclusion The newborn rat exposed hyperoxia,the up-regulation of Smad4 protein expression and the down-regulation of Smad7 protein expression are imposible closely related to the happen and development of CLD pulmonary fibrosis.

Objective To investigate the variation in expression and the significance of markers indi-cating typeⅠalveolar epithelial cells ( AECⅠ) and type Ⅱ alveolar epithelial cells ( AECⅡ) in hyperoxia induced bronchopulmonary dysplasia( BPD) model. Methods A total of 80 term normal Wistar rats were randomly devided into model group (85% oxygen) or control group (room air) within 12 h after birth,with 40 rats in each group. On day 7,day 14,day 21 after exposure,the pathological characteristics of lung tissues were observed using HE staining, the expression and location of AECⅠ marker aquaporin 5 ( AQP5 ) and AECⅡmarker surfactant protein-C ( SP-C) were examined using immunofluorescence double staining. West-ern blot analysis was employed to examine the expressions levels of AQP5 and SP-C proteins,while real-time PCR was used to evaluate the mRNA expression of AQP5 and SP-C. Results Alveolar developmental disor-der was observed in lung tissues of the model group,including fewer,larger,simplified alveoli,thicker alveo-lar walls,and fewer alveolar secondary septa. Immunofluorescence double staining showed increased and dis-organized AQP5 and SP-C expression, with significantly higher ratio of double-stained cells/SP-C positive cells in the model group ( P<0. 001 ) . Comparing to the control group, the expression of AQP5 and SP-C protein increased from 7 d after hyperoxia exposure,which continued to 21 d. The mRNA expression levels of these two markers both significantly increased in the model group compared with the control group, with AQP5 starting from 7 d while SP-C starting from 14 d after hyperoxia exposure (P<0. 05),and the differ-ence between two groups became more significant with the exposure time extending. Conclusion The expression of AECⅠ marker AQP5 and AECⅡ marker SP-C both increase in the lung tissues of hyperoxia induced BPD newborn rats,with more AECⅡ transdifferentiated into AECⅠ. These changes of the markers indicate that there is excessive transdifferentiation of AECⅡ in the recovery process after BPD lung injury.

Objective To investigate p16 promoter methylation in premature rats with chronic lung disease induced by hyperoxia. Methods Eighty premature Wistar rats were randomly divided into two groups: hyperoxia group (fraction of inspiratory oxygen) 0. 90 and control group (fraction of inspiratory oxygen 0. 21), 40 rats for each group. Semi-nested methylation specific polymerase chain reaction and methylation specific polymerase chain reaction were applied respectively to detect p16 promoter methylation in lung tissues. Additionally, p16 mRNA and protein expressions in lung tissue were detected by reverse transcription- polymerase chain reaction, Western blot and immunohistochemistry method. Results The methylation was not found in control group by seminested methylation specific polymerase chain reaction and methylation specific polymerase chain reaction, while was found in different aged rats of the hyperoxia group. The methylation detection rate was higher by using the semi-nested methylation-specific polymerase chain reaction (52.5%, 21/40) than that by methylation specific polymerase chain reaction (42.5%, 17/40) in the hyperoxia group,but there was no statistically significant difference between the two methods. The p16 mRNA in the hyperoxia group were significantly lower than in the control group at day 7, 14 and 21(1.73 ± 0.40 vs 2.11±0. 37,1.29±0. 19 vs 1.60±0. 27,0. 95±0.25 vs 1.72±0. 34, t=2.19, 2.95 and 10. 43,P＜0. 05). The p16 protein expressions by western blot in the hyperoxia group were significantly lower than in the control group at day 7, 14 and 21 also (88. 1±8. 7 vs 95.0±4.1,65.7±4.5 vs 83. 5±13.6 and 50.4±4.9 vs 86.7±11.9, t=2.27,3.95 and 13.40,P＜0.05). The expression of p16 mRNA (1.06±0.61) and protein (62.32±25.65) in lung tissues of rats with methylation was lower than that without methylation (1.63±0.62 and 94.93±22.21, respectively) (t=2.95, OR=0. 86;t=4.28, OR=0. 85,P＜0.01, respectively). Conclusions Exposure to hyperoxia might induce p16 promoter methylation in lung tissues in premature rats. Methylation risk increases as exposure time extends. p16 promoter methylation induced by hyperoxia might participate in the mechanism of lowering p16 mRNA and protein expression, but might not result in p16 gene silence.

Objective To explore the incidence rate and high-risk factors for bronchopulmonary dysplasia(BPD) in premature infants of mechanical ventilation.Methods From Jan 2008 to Dec 2009,196 very low birth weight infants with gestational age less than 32 weeks in our NICU were enrolled in the study.61 cases had the histories of mechanical ventilation.The clinical materials of 21 cases with BPD were compared to 41 cases without BPD in retrospective analysis.Results The total incidence of BPD in the very low birth weight infants with gestational age less than 32 weeks was 10.7%,and 34.4% in those infants with mechanical ventilation.The gestational age and birth weight of BPD group were lower than those without BPD,and the rates of premature rupture of fetal membrane and complicated neonatal respiratory distress syndrome (NRDS),postnatal infection,with long time intravenous nutrition in BPD group were higher than those without BPO control (P<0.05).Gender,asphyxia history,the use of pulmonary surfactant (PS),positive end-expiratory pressure,and mean airway pressure were not different significantly between two groups (P>0.05).Peak inspiratory pressure (PIP),the time of mechanical ventilation and oxygen administration were different significantly between two groups (P<0.05).NRDS,postnatal infection,the duration of ventilation,and hyperoxia were the risk factors for BPD,and the regression coefficient were 3.683,1.541,1.188 and 1.647.Conclusion Preventing premature,low birth weight,NRDS,shortening the duration of high peak inspiratory pressure and hyperoxia with mechanical ventilation and the use of the parenteral nutrition,managing the infection of the prenatal and postnatal are the key points of preventing BPD.

Objective To evaluate the effects of supine and prone position on ventilation function in neonates in the initial six-hour period after weaning. Methods Sixty-four neonates weaned from mechanical ventilation and with normal body temperature hospitalized from Sep. 2004 to Apr. 2006 in our NICU were randomly divided into prone group and supine group. All of them were oxygen administrated through head net, oxygen flow rate was adjusted continously to keep SpO2 at normal level by monitoring SpO2 and RR. FiO2、RR were recorded at 15 minutes,1 h,2 h,3 h,4 h,5 h,6 h after weaning. Arterial blood gas was meas-ured at 1 h ,6 h after weaning and A-aDO2, RI, OI were calculated. Results (1) At 1～6 h after weaning the values of FiO2 in prone group were significantly lower than those in the supine group(P<0.01). (2) After weaning there was a decreasing tendency of RR in the prone group and the significant decrease was found at 4 h ,5 h ,6 h compared with supine group (P<0.01). (3) At 1h and 6h after weaning, the value of PaO2 and OI were significantly higher and the value of A-aDO2, RI were lower in the prone group than in the supine group(P<0.05,P<0.01). (4) At 6 h the PaCO2 in prone group were obviously higher than that in supine group (P<0.05). Conclusion At first 6h after weaning prone position can improve ventilation functions.

Objective To explore the role of anterior horn index (AHI) in magnetic resonance imaging (MRI) outcome after intraventricular hemorrhage (IVH) and the correlation factors of IVH in preterm infants.Methods We selected 55 preterm infants with IVH(Ⅱ-Ⅳ degree) confirmed by MRI as case group,and 55 preterm infants with normal MRI as control group,all the cases were admitted in neonatal medical wards in our hospital from January 2009 to September 2011.Then 30 infants of case group were scaned for the second time,to see if they had posthemorrhagic ventricular dilatation (PHVD) and compare the AHI with the last time MRI,and analysis the related factors associated with IVH in preterm infants.Results MRI results:9 infants had PHVD,and the AHI rised (0.36 ± 0.05 v s 0.46 ± 0.06,P ＜ 0.01);21 infants didn't have PHVD,and the AHI decreased (0.31 ± 0.02 vs 0.30 ± 0.02,P ＜ 0.01).Logistic regression analysis:vaginal delivery,use of pulmonary surfactant,mechanical ventrilator care were associated with IVH (P ＜0.05).Conclusion AHI can be used for judging PHVD in preterm infants with IVH.Preterm infants with IVH,especially grade Ⅱ should be monitored AHI.Vaginal delivery and mechanical ventrilator may be risk factor of IVH in preterm infants,while use of pulmonary surfactant may a protective factor of IVH.

Objective To investigate the effect of hyperoxia on fluid transport by fetal distal lung epithelia(FDLE) and the expression of epithelial sodium channel(ENaC) in these cells.Methods FDLE were isolated and randomized into hyperoxia group and normoxia group,which were primarily cultured under hyperoxic or normoxic conditions,respectively.Fluid transport was measured using monolayers of FDLE cultured on Transwell permeable inserts.Western blot was applied to examine the α-ENaC expression.Results Fluid transport across monolayer of FDLE was increased in cells exposed to hyperoxia compaired with cells cultured in normoxic conditions (1.78 ± 0.19 vs 1.06 ± 0.11,P ＜ 0.001).Amiloride significantly decreased the fluid transport in both of the hyperoxia and normoxia groups,but in the presence of amiloride there were no difference between the two groups.The expression of α-ENaC was inhibited by hyperoxia to some extent(24h:0.44 ±0.04 vs 0.40 ±0.04,P=0.22; 48h:0.35 ±0.03 vs 0.47 ±0.06,P =0.03).Conclusion Hyperoxia enhanced total and amiloride-sensitive fluid transport by FDLE.However,the expression of α-ENaC decreased in these cells.

Objective To investigate the effect of hyperoxia on the transdifferentiation level of type Ⅱ alveolar epithelial cells (AEC Ⅱ) in vivo and in vitro,in order to illuminate the mechanism of epithelial injury in bronchopulmonary dysplasia (BPD).Methods Newborn Wistar rats were randomly devided into control group (room air inhalation) or model group (85％ oxygen inhalation) after birth.Lung tissue sampling and AEC Ⅱ isolation was conducted on 7 d,14 d,21 d.Type Ⅰ alveolar epithelial cells (AEC Ⅰ) marker aquaporin 5 (AQP5) and AEC Ⅱ marker surfactant protein C (SP-C) were examined by Western blot and florescent real-time PCR.AEC Ⅱ isolated from normal newborn rats was randomly devided into normoxia group (21％ oxygen) or hyperoxia group (85％ oxygen) after 24 h culture,and continued culturing for another 48 h in vitro.Then the morphological changes of cells were observed under inverted phase contrast microscope.The expression and location of markers for AEC Ⅰ and AEC Ⅱ was examined by immunofluorescence double staining.The protein expression of AQP5 and SP-C was evaluated by Western blot,and the mRNA expression of these markers was examined by florescent real-time PCR.Results In AEC Ⅱ isolated from the animal models,the AQP5 protein expression increased from 7 d while the SP-C expression decreased from 14 d in the model group comparing with the control group.In the model group,AQP5 mRNA expression increased and SP-C mRNA expression decreased since 7 d after hyperoxia exposure (P ＜ 0.05),with the difference between groups more obvious as exposure time extending.After culturing in vitro,AEC Ⅱ isolated from normal newborn rats expressed more AQP5 and less SP-C,with more cells double stained in the hyperoxia group compared with the normoxia group,examined by immunofluorescence double staining.The protein and mRNA examination results both showed that AQP5 expression increased and SP-C expression decreased in the hyperoxia group compared with the normoxia group (P ＜0.01).Conclusion After hyperoxia exposure,no matter in vivo or in vitro,the expression of AEC Ⅱ marker SP-C decreases while the expression of AEC Ⅰ marker AQP5 increases.These results indicate that the excessive transdifferentiation of AEC Ⅱ takes part in the recovery process after hyperoxia induced lung injury.