In view of the characteristics of the learning curve for medical students,the ' three phases and seven steps' case-based learning model was designed and implemented by Changzheng Hospital,the Second Military Medical University.This model was carried out in the theoretical study stage,the first round of internship and the second round of internship.Cases of single diseases,multiple diseases involving variant systems and a variety of diseases involving different department were enrolled for analysis and discussion.Implementation of each case study was divided in seven procedures:determining learning objective and choosing typical case,studying case and raising questions,panel discussions and establishment of common problems,looking up for information to answer questions and preparing report slide,large group discussions,summary and evaluation.'Three phases and seven steps' case based learning model ensure the width and depth of basic medical knowledge learned by the students.With the practice of this model,the basic medical knowledge was constructed systemically and comprehensively by medical students.Students' abilities of problem-analyzing and problem-solving as well as clinical research were developed.This model was effective according to our practice and was worth spreading out.

Objective To investigate the clinical significance of hepatocyte nuclear factor 4α(HNF4α)in rectal cancer and its relationship with prognosis.Methods Real-time PCR was designed to detect the expression of HNF4αon mRNA level and the immunohistochemistry was used to determine the expression of HNF4αon protein level in rectal cancer tissue.The relationship between HNF4αexpression and clinical characteristics was also analysed.The Kaplan-Meier method was used for univariate analysis and a Cox proportional hazards regression model was performed for multivariate analysis.Results HNF4αwas low expressed both on mRNA (t=6.092,P<0.001)and protein level (χ2 =15.230,P<0.001)in rectal cancer tissue.HNF4αexpression on protein level was related with the clinical stage (χ2 =48.311,P<0.001),depth of invasion (χ2 =23.911,P<0.001),histological differentiation (χ2 =20.787,P<0.001),lymph node metastasis (χ2 =39.064,P<0.001)and distant metastasis (χ2 =5.146,P=0.04),while age and gender were not relevant.The cumulative 3-year overall survival of patients with low HNF4αexpression (43.8%)was much worse than the patients with high HNF4αexpression (95 .5%),and the difference was statistically sig-nificant (P<0.001).Univariate analysis revealed that HNF4αexpression (χ2 =28.778,P<0.001),differ-entiation (χ2 =26.680,P<0.001 ),clinical stage (χ2 =32.702,P<0.001 ),depth of invasion (χ2 =6.226,P=0.013),lymph node invasion (χ2 =15.270,P<0.001)and distant metastasis (χ2 =21.817, P<0.001)were statistically significant worse predictors for rectal cancer,whereas age and gender were not rel-evant.The multivariate Cox proportional hazard analysis revealed that HNF4αlow expression (RR=6.084, P=0.028)was independent prognostic markers for 3-year overall survival in the patients with rectal cancer. Conclusion HNF4αwas closely related to the tumorigenesis and progression of rectal cancer,which is an independent prognostic marker for rectal cancer,and which may be an effective target for the therapy of rectal cancer.