BACKGROUND: Mechanisms related to bone fracture and nonunion have been clarified, but the healing time and treatment strategy of delayed union remain controversial. OBJECTIVE: To establish a reliable model of femoral delayed union using external fixation in the New Zealand white rabbit. METHODS: Seventy-two New Zealand white rabbits were randomized to three groups. After removal of 10-mm femoral middle bone cortex with internal and external periosteum and bone marrow, a uniplanar external fixator was used. There was a 1 mm gap between broken ends (group A), and the broken ends were sealed by bone wax (group B). For controls, only bone cortex was cut and then fixed to contact the broken ends. The gross, radiological and histological observations were performed to observe the bone healing at 4, 8 and 12 weeks after modeling. RESULTS AND CONCLUSION: The control group achieved bone healing at the 4th week, which was considered as the normal time of bone healing. The groups A and B achieved healing at the 12th week, which was remarkably longer than that in the control group. The rabbit femoral delayed union model showed the typical X-ray imaging and pathological features of delayed union. Our results suggest that the model is reasonable and reliable, which can provide reference for clinical research.

The periods of the medical students' clinical practice is an important transition from medical theory to medical practice.According to the medical interns' expectations,such as the clinical tutor' level,hardware of the department,daily medical process and our department' s experiences,we grope for much better teaching methods that can meet medical interns' expectations and evaluate the new teaching methods.The basic clinical skills of medical students and the teaching level of gastrointestinal surgery department have been effectively improved.

To improve the medical students'comprehensive quality and clinical practice ability,we summarize personal and the department's experiences,enhance the students'education on their entering into clinic,accentuate basic skills of medical paperwork and endeavor to foster students'surgically logic thinking ability.

Objective To evaluate the diagnostic capabilities of T2 WI features in peripheral zone prostate cancer.Methods The characteristics of T2 WI in 56 cases of peripheral zone prostate cancer,75 cases of benign prostatic hyperplasia and 7 cases of prostatitis confirmed by pathology were analyzed retrospectively.Eight indexes were initially screened byχ2 test,then indexes with significant difference were entered into multivariate Logistic regression analysis.Results The indexes showing statistical differences between prostate cancer and benign prostatic disorders were as following:lesion shape,signal intensity,signal uniformity,boundary of peripheral zone and transition zone,the volume of peripheral zone and prostatic capsule on T2 WI (P<0.05).Margin of lesion and capsule between two groups were not statistical differences (P>0.05).By multivariate Logistic analysis,the statistically significant difference were found in lesion shape, the volume of peripheral zone,prostatic capsule and boundary of peripheral zone and transition zone.Conclusion The lesion shape, volume of peripheral zone and prostatic capsule on T2 WI are independent risk factors for peripheral zone prostate cancer.

Objective To evaluate the value of T2WI scores for diagnosis and differential diagnosis of transition zone prostate cancer(PCa).Methods T2WI of 43 cases of transition zone PCa and 91 cases of benign prostatic hyperplasia(BPH) were analyzed retrospectively.Transition zone T2WI signs were divided into the main signs and the secondary signs, which were given different scores and were evaluated separately by receiver operating characteristic (ROC) curve for their diagnostic value.Results In a total of 11 scores sections (-1-10), as the increase of scores, the sensitivity of transition zone PCa was decreased while the specificity and positive predictive value were both increased.According to the ROC curve, when the critical value of scores≥4.5, the sensitivity, specificity, negative predictive value, and the accuracy were 81%,73.3%,90.9%,70.4% respectively.When the scores ≥8.5,the specificity and positive predictive value were both 100%.When the scores ≥0.5 and ≥1.5,the negative predictive value were 100%.Conclusion T2WI scores can quantitatively analyze the transition zone PCa,which has an important value to improve the clinical diagnosis and guide treatment.

Objective To investigate the diagnostic value of multiparametric MRI in early prostate cancer(PCa) based on PI-RADS version 2.Methods 27 surgically-proved early PCa patients were collected in this retrospective study.T2WI,DWI and DCE were evaluated by two blinded radiologists.By 12 sub-region classification method the possibility of the presence of cancer at each sub-region was scored according to the PI-RADS V2.The receiver operating characteristic (ROC) curve was used to analyze the diagnosic efficacy of the following 4 protocols:T2WI alone(protocol 1),T2WI+DWI(protocol 2),T2WI+DCE(protocol 3),T2WI+DWI+DCE(protocol 4).The sensitivity,specificity and accuracy for each protocol were calculated.The average scores of cancerous sub-regions and non-cancerous sub-regions were calculated and the independent sample t test was used to compare the four protocols.Results 324 sub-regions were analyzed in 27 early PCa patients and then divided into 119 cancerous sub-regions and 205 non-cancerous sub-regions,including 64 peripheral zone cancerous sub-regions and transition zone cancerous sub-regions.In protocol 1-4, the average scores of cancerous sub-regions in orderwere 3.13±1.19,3.27±1.15,3.28±1.23, 3.33±1.16,respectively.Non-cancerous sub-regions's scores in order were 1.98±0.90,1.91±0.91, 2.03±0.99,1.94±0.96 respectively and there were significant differences among each protocol (P<0.05).The area under the ROC curve of the 4 protocols for region-based analysis were displayed in descending order: protocol 4 (0.819), protocol 2 (0.810), protocol 3 (0.772), protocol 1 (0.765) and there were no significant differences between any two protocols (P>0.05).In four protocols, the sensitivity in order were 45.40%, 56.30%, 59.70%, 61.34%, while the specificity in order were 95.10%, 96.10%, 89.80%, 96.60%, and the accuracy in order were 76.85%, 81.48%, 78.70%, 83.65%.Conclusion Multiparametric MRI can improve the diagnostic accuracy for the detection of early PCa, and T2WI+DWI+DCE is with the highest value.The PI-RADS V2 system is a better semi quantitative method for evaluation of early PCa.

Objective To evaluate MRI in judging the therapeutic effect of argon-helium cryoablation therapy for prostate cancer. Methods The clinical data and imaging materials of 16 patients with prostate cancer , who had received ultrasound-guided argon-helium knife cryogenic treatment at authors ’ hospital during the period from March 2012 to Oct. 2014, were retrospectively and comprehensively analyzed. The preoperative and postoperative laboratory test results were compared with MRI findings, and the ablation effect was assessed, focusing on the surgical residue, metastasis, etc. Results One months after the surgery, MRI demonstrated that satisfactory ablation extent was obtained in all patients, the ablated tumor tissue was characterized by long-T2 signal and no obvious recurrence could be found on DWI and DCE-MRI. A slight decrease of PSA level was observed. Six months after the surgery, MRI revealed that the prostate size was significantly reduced, PSA level was markedly decreased and no obvious evidence of recurrence was observed. No severe postoperative complications, such as urethral necrosis, urethral stricture or urethro-rectal fistula, occurred. During the 6-month following-up time, one patient died from other causes. Conclusion MRI has excellent clinical application value in estimating the ablation extent and in judging postoperative recurrence or metastasis of prostate cancer after argon-helium cryoablation treatment.

Objective To evaluate the effect of endovascular stent-graft exclusion used in of thoracic aortic dissection aneurysm. Methods by retrospectively study the clinical collections of 34 Stanford B aortic dissection cases which were treated by endovascular stent-graft exclusion in the condition of full anaesthesia from 2002 to 2005.Results 34 patients were successfully stened but one patient failed because the guide-wire could not get into the real vascular and no perioperative death.The range of postoperative follow-up was form 3 months to 29 months,the average of which was 15 months.24 of the patients accepted a reexamination of CT,9 of them were performed DSA at the same time.Conclusion Endovascular stent-graft exclusion is safe and efficient for Stanford B aortic dissection aneurysm.Further follow-up is necessary to evaluate its long-term effectives.

Objective To explore the effect and mechanism of fragile site WWOX gene on regulating proliferation of gallbladder cancer cells in vitro. Methods The pcDNA3.0 - WWOX recombinant plasmid which was previous successfully built was transfected to GBC-SD cells and empty carrier by liposome medium. Liposome and GBC-SD were served as the negative control and the blank control,respectively. After 48 hours transfection, inverted microscope was used to observe the changes of gallbladder cancer cells' morphology,MTT and BrdU were used to detect the proliferation level of gallbladder cancer cells,and flow cytometry instrument was used to detect the change of the cell proliferation cycle. Results The results of inverted microscope shown: the number of GBC-SD cells in pcDNA3.0-WWOX group decreased significantly,the suspension cells and cell debris increased,while cells in the vector control,NC and Mock groups were in normal proliferation state. MTT test showed the proliferation levels of GBC-SD cells in pcDNA3.0-WWOX group was lower than those in the control group in 24 h,48 h,72 h,96 h and 120 h,and the differences were statistically significant(P < 0.05). The cell proliferation activity in the pcDNA3.0-WWOX group was obviously inhibited over time. BrdU detection results showed the cell proliferation rate of pcDNA3.0 - WWOX group was(0.44±0.03),while that in the three control groups was(0.78±0.02), (0.81±0.01)and(0.85±0.01),respectively. It showed that cell proliferation activity in pcDNA3.0-WWOX group was lower than the control groups,and the difference was statistically significant(P < 0.05). Cell cycle detection showed the cells increased in G0/G1 phase and decreased in G2/M and S phases of pcDNA3.0-WWOX group. The cell apoptosis rate was significantly higher and the proliferation index was significantly lower than those of the control groups(P < 0.05). However,there were no significant differences among the three control groups(P > 0.05). Conclusion The overexpression of WWOX gene in vitro could effectively inhibit the proliferation activity of gallbladder cancer cells. WWOX might participate in the development of the malignant biological behavior of gallbladder cancer cells. It is expected to become a new potential target for the gene therapy to gallbladder cancer.

Objective:To explore the application effect of case-based learning (CBL) in teaching magnetic resonance imaging (MRI) for non-imaging clinical professional postgraduates.Methods:Eighty non-imaging clinical professional postgraduates who had standardized residency training from 2017 to 2019 were selected as the participants and were randomly divided into two groups, experimental group and control group. The experimental group adopted CBL, and the control group adopted traditional teaching mode. After the standardized training in the radiology department, the differences in image reading scores, theoretical scores and course evaluation were compared between the two groups. SPSS 25.0 statistical software was used for analysis. Independent t test was used for the measurement data of normal distribution, Mann-Whitney U test was used for the measurement data of skewed distribution, and categorical variables were compared by chi-square test. Results:In the reading scores of MRI, the scores of the experimental group and the control group were (82.53 ± 5.72) points and (77.38 ± 6.14) points respectively, and the number of students in the experimental group whose reading scores were between 80-100 segment was 63.6% higher than that in the control group, with significant differences between the two groups ( P < 0.001), but without significant differences in theoretical average scores between the two groups ( P > 0.05). In addition, in the course evaluation, except for the index of learning burden, there were significant differences in other indexes between the experimental group and the control group ( P < 0.05). Conclusion:In the teaching of MRI, the application of the CBL helps non-imaging clinical professional postgraduates improve their MRI diagnostic thinking and independent reading ability.