AIM:To introduce and evaluate two methods for sample size calculation in doseresponse research.METHODS:The methods used for sample size calculation in dose-response research include Cochran-Armitage trend(CAT) test proposed by Jun-mo Nam and the Unified contrast(CUC) method proposed by Chang. This paper takes the example of binary data,uses the two methods to calculate the required sample size and evaluate the power by simulation under the assumption that the response rate had a linear relationship with dosage under the logit scale.RESULTS:When the probability of response followed a linear trend on the logit scale, the sample sizes estimated from the two methods are approximately equal in various parameter's settings.The simulated power of CAT test was close to the expected one,however,the simulated power of CUC method was obviously affected by the values of contrast coefficient,if a contrast whose coefficients parallel the expected response, the CUC method was more powerful. CONCLUSION:When the probability of response follows a linear trend over dosage on the logit scale,the two methods reach almost the same result,in such circumstance,the Chang's unified contrast method will obtain an increasing power.

Objective To evaluate dexmedetomidine-induced cardioprotection in a mouse model of lung ischemia-reperfusion (I/R) and the relationship with endoplasmic reticulum stress.Methods Forty healthy SPF male C57BL/6J mice,weighing 20-24 g,aged 8-10 weeks,were divided into 4 groups (n=10 each) using a random number table:sham operation group (Sham group),lung I/R group (I/R group),dexmedetomidine group (Dex group) and dexmedetomidine plus atipamezole (specific α2-adrenergic receptor antagonist) group (DA group).The model of lung I/R injury was established by clamping the left hilum of lung for 30 min followed by 180 min of reperfusion.In group Sham,only sternotomy was performed,the hilum of lung was not clamped,and the mice were mechanically ventilated for 210 min.In Dex and DA groups,dexmedetomidine 20 μg/kg and dexmedetomidine 20 μg/kg plus atipamezole 250 μg/kg were injected intraperitoneally,respectively,at 30 min before establishment of the model.At 180 min of reperfusion,blood samples were collected from the orbit for determination of creatine kinase-MB (CK-MB) and lactic dehydrogenase (LDH) activities in serum.The animals were then sacrificed,and hearts were removed for determination of apoptosis in cardiomyocytes (by TUNEL) and expression of phosphorylated c-Jun N-terminal kinase (p-JNK),caspase-12,CCAAT/enhancer-binding protein homologous protein (CHOP) and glucose-regulated protein 78 (GRP78) in myocardial tissues (by Western blot),and expression of JNK,caspase-12,CHOP,GRP78 mRNA in myocardial tissues (by real-time polymerase chain reaction).Apoptosis index was calculated.Results Compared with Sham group,the serum CKMB and LDH activities and apoptosis index were significantly increased,the expression of p-JNK,JNK mRNA,and caspase-12,CHOP and GRP78 protein and mRNA was up-regulated in I/R,Dex and DA groups (P＜0.01).Compared with I/R group,the serum CK-MB and LDH activities and apoptosis index were significantly decreased,the expression of p-JNK,JNK mRNA,and caspase-12 and CHOP protein and mRNA was down-regulated,the expression of GRP78 protein and mRNA was up-regulated in group Dex,and the expression of GRP78 protein and mRNA was significantly up-regulated (P＜0.01),and no significant change was found in the other parameters in group DA (P＞0.05).Compared with DEX group,the serum CK-MB and LDH activities and apoptosis index were significantly increased,the expression of pJNK,JNK mRNA,and caspase-12 and CHOP protein and mRNA was up-regulated (P＜0.01),and no significant change was found in the expression of GRP78 protein and mRNA in DA group (P＞0.05).Conclusion Dexmedetomidine can reduce myocardial injury induced by lung I/R,and the mechanism may be related to activation of α2-adrenergic receptors and inhibition of endoplasmic reticulum stress in myocardial cells of mice.

AIM: To investigate the variations of heme oxygenase-1/carbon monoxide system in lung ischemia-reperfusion injury and effects of puerarin on the system.METHODS: The unilateral lung ischemia-reperfusion model was replicated in vivo.Rabbits were randomly divided into three groups(n=10 in each): control group,ischemia-reperfusion(I-R) group and puerarin group.The blood specimens collected at times before ischemia,ischemia 1 h,reperfusion 1 h,3 h and 5 h were tested for the contents of carboxyhemoglobin(COHb) and cyclic guanosine monophosphate(cGMP).The lung tissues sampled at 5 h after reperfusion were assayed for wet/dry weight ratio(W/T),the injured alveoli rate(IAR) and the activity of HO-1.The changes of ultrastructure were observed under electron microscope.The tissue slides were also stained by immunohistochemistry(IHC) and in situ hybridization(ISH) to detect the expression of HO-1.RESULTS: The plasma content of COHb and cGMP in I-R and puerarin group increased in a time-dependent manner after I-R compared with control group,but the increment in puerarin group was higher than that in I-R group(P

Objective To observe the effects of Yiqi Huoxue Tongluo Jiedu fang (YHTJF) on pneumocyte apoptosis after lung ischemia/reperfusion (I/R) injury (LIRI) in mice and to investigate whether c-Jun N-terminal protein kinase (JNK) is involved in the mechanism of apoptosis.Methods Seventy C57BL/6J male mice were randomly divided into seven groups:normal control group (C group),carboxyl methyl cellulose-Na+normal control group (CMC-Na+C group),CMC-Na+sham group (CMC-Na+S group),CMC-Na+I/R group (CMC-Na+I/R group) and CMC-Na+YHTJF-low,-middle,-high dose groups (CMC-Na+YL,CMC-Na+YM,CMC-Na+YH groups).C group did not undergo any processing;in CMC-Na+S group,only was chest opened without clipping the lung hilum;in the rest of the four groups,they all underwent opening of the chest and clipping the lung hilum for 30 minutes,then the clipping of artery was relieved and left lung reperfusion was carried out for 3 hours.After operation,the mice were sacrificed,the lung tissues were harvested.Under light and electron microscopes,the lung morphological and ultra-structural changes were observed,and the changes of index of quantitative evaluation for alveolar damage (IQA) were determined.The terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) was applied to evaluate the apoptosis index (AI) of the lung tissues.The protein and mRNA expressions of JNK and glucose regulating protein 78 (GRP78) in lung tissues were detected by Western Blot and reverse transcription-polymerase chain reaction (RT-PCR);the correlations between lung AI and the expressions of mRNA and protein of JNK and GRP78,IQA were analyzed.Results Compared with CMC-Na+S group,IQA,AI and mRNA and the protein expressions of JNK and GRP78 in CMC-Na+I/R group were obviously higher [IQA:(74.00 ± 7.31)％ vs.(7.00 ± 1.23)％,AI:(64.40 ± 11.97)％ vs.(5.60 ± 1.14)％,JNK mRNA (gray value):1.143 ± 0.284 vs.0.152 ± 0.128,GRP78 mRNA (gray value):0.897 ± 0.129 vs.0.284 ± 0.044,JNK protein (A value):0.428 ± 0.074 vs.0.073 ± 0.052,GRP78 protein (A value):1.075 ± 0.145 vs.0.589 ± 0.060].Compared with CMC-Na+I/R group,the IQA,AI,protein and mRNA expressions of JNK and GRP78 in CMC-Na+YL,CMC-Na+YM,CMC-Na+YH groups were all lower,and the degree of reduction in group CMC-Na+YM was the most remarkable,greater than that in CMC-Na+YL or CMC-Na+YH group [IQA:(26.20 ± 3.35)％ vs.(34.00±5.34)％,(41.20±9.18)％,AI:(29.40±3.05)％ vs.(48.20±3.83)％,(39.20±6.14)％,JNK mRNA (gray value):0.681 ± 0.130 vs.0.804 ± 0.153,0.938 ± 0.11,GRP78 mRNA (gray value):0.450 ± 0.105 vs.0.747 ± 0.231,0.566 ± 0.115,JNK protein (A value):0.188 ± 0.049 vs.0.261 ± 0.065,0.209 ± 0.063,all P ＜ 0.01],compared with the CMC-Na+I/R group,the expression of GRP78 protein was obviously higher in CMC-Na+YH,CMC-Na+YL,CMC-Na+YM groups and the most remarkably high was in CMC-Na+YH group (A value:1.429 ±0.226 vs.1.130±0.169,1.128 ±0.177,all P ＜ 0.01).The apoptosis of each group was mainly in the pulmonary vascular endothelial cells and alveolar epithelial cells,and brown particles were positive cells under light microscope.Under transmission electron microscope:nuclear pyknosis and margination under the nuclear membrane,cytoplasm condensed,lamellar bodies decreased and emptying increased,cell membrane microvilli decreased or disappeared,mitochondria swelling,inflammatory cells increased in alveolar septum and adhering onto the capillary walls could be seen in CMC-Na+I/R group.Compared with CMC-Na+I/R group,the lung tissue ultrastructural damage alleviated,ultrastructure of alveoli clearly seen,nuclear chromatin relatively uniform,cytoplasm increased,type Ⅱ alveolar epithelial cell surface microvilli relatively plenty,lamellar corpuscle number increased,mitochondria swelling ameliorated in CMC-Na+YH,CMC-Na+YL,CMC-Na+YM groups and the most remarkable one was CMC-Na+YM group.AI was significantly positive correlated with the mRNA and protein expressions of JNK,GRP78 and IQA (r =0.907,0.928,0.880,0.712,0.911,all P ＜ 0.01).Conclusions YHTJF may effectively alleviate the cell apoptosis in mice LIRI,and its mechanism may be related to the inhibition of JNK pathway.

AIM:To explore the relationship between apoptosis in the lung tissues and lung ischemia/reperfusion injury,and to observe the effects of human thioredoxin (hTrx) on apoptosis in lung ischemia/reperfusion injury. METHODS:The single lung in situ ischemia/reperfusion animal model was used. Eighty four Wistar rats were randomly divided into control group (control),groups of ischemia for 1 h and reperfusion for different times (IR1h,IR3h,IR5h),and groups of IR + human thioredoxin treatment (IR1h + hTrx,IR3h + hTrx and IR5h + hTrx). Transmission electron microscope (TEM),terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and immunocytochemistry techniques were used to observe apoptosis,apoptosis signal-regulating kinase 1 (ASK1) and expression of Bcl-2 and Bax in various phases of lung ischemia/reperfusion. RESULTS:Cell apoptosis in lung tissues was significantly high,ASK1,Bcl -2 and Bax protein were upregulated in lung tissues of lung ischemia/reperfusion injury as compared to control (all P

AIM:To investigate the effect of L-arginine(L-Arg) on expression of bcl-2,bax mRNA during pulmonary ischemia and reperfusion injury(PIRI) in rabbits.METHODS: Single lung ischemia and reperfusion animal model was used in vivo.The rabbits were randomly divided into three groups: sham operated group(sham,n=12),ischemia-reperfusion group(I/R,n=12) and I/R+ L-arginine group(L-Arg,n=12).Changes of several parameters,which included apoptotic index(AI),wet to dry ratio of lung tissue weight(W/D) and index of quantitative assessment of histologic lung injury(IQA),were measured at 300 min after reperfusion in lung tissue.Meanwhile the location and expression of bcl-2,bax mRNA as well as the ratio of bcl-2 mRNA/bax mRNA were observed.The lung tissue was prepared for light microscopic and electron microscopic observation at 60,180 and 300 min after reperfusion.RESULTS: As compared with I/R group,in intima and extima of small pulmonary artery,alveoli,and bronchiole epithelia,the expression of bcl-2 mRNA and the ratio of bcl-2 mRNA/bax mRNA were increased,and the expression of bax mRNA was decreased in L-Arg treatment group.The values of AI,W/D and IQA showed significantly lower than that in I/R group at 180 minutes after reperfusion in lung tissue(P

Objective To investigate the effect of dexmedetomidine (DEX) on the reduction of brain injury induced by lung ischemia/reperfusion (I/R) in mices through inhibiting excessive endoplasmic reticulum stress response (ERS).Methods Fifty healthy SPF male C57BL/6J mices,weighing 20-24 g,aged 8-10 weeks,were divided into 5 groups (n =10 each) using a random number table:sham operation group (sham group),lung ischemia/reperfusion group (I/R group),atipamezole goup (Atip group),dexmedetomidine group (DEX group),dexmedetomidine plus atipamezole group (DA group).The model of lung I/R injury was established by clamping the left hilum of lung for 30 min followed by reperfusion for 180 min.In Atip,DEX and DA groups,atipamezole 250 μg/kg,dexmedetomidine 20 μg/kg and dexmedetomidine 20 μg/kg plus atipamezole 250 μg/kg were injected intraperitoneally,respectively,at 30 min before modeling,other procedures were as the same as the I/R group.At 180 min of reperfusion,the animals were sacrificed and the brain tissues were harvested for the observation of morphological changes.The Caspase-3 activity and the apoptosis index of the brain cells were also determined.The levels of protein and mRNA expression of p-JNK,Caspase-12,CHOP and GRP78 in brain tissues were detected by Western blot and RT-PCR.The datas were analyzed using SPSS 19.0 software and multiple-group comparisons were performed using one-way ANOVA,and P ＜ 0.05 for the difference was statistically significant.Results Compared with the sham group,the Caspase3 activity and brain cell apoptosis index,the protein levels and mRNA expressions of p-JNK,Caspase12,CHOP,GRP78 were significantly increased (P ＜ 0.01),brain tissues had obvious damage in I/R,Atip,DEX and DA groups;compared with I/R,Atip and DA group,brain tissues damage was obvious reduced in DEX group,and the Caspase3 activity,brain cell apoptosis index,the protein levels and mRNA expression of p-JNK,Caspase12,CHOP in DEX group were significantly lower,and GRP78 expression increased significantly (P ＜ 0.01).Comparisons among I/R,Atip and DA groups,there were no significant differences in degree of brain injury,Caspase3 activity,brain cell apoptosis index,the protein levels and mRNA expressions of p-JNK,Caspase12,CHOP (P ＞ 0.05),while the expression of GRP78 in DA group was significantly increased (P ＜ 0.01).Conclusion DEX can effectively relieve the brain injury induced by lung I/R in mice,which may be associated with stimulation of α2 adrenergic receptor and inhibition of excessive endoplasmic reticulum stress response and reducing brain cell apoptosis.