Objective To construct a shuttle plasmid for inducible gene expression in Borrelia burgdorferi (B.burgdorferi) with an advantage of flexible genetic manipulation.Methods The IPTG-inducible lac repressor/operator system from Escherichia coli (E.coli) was adopted and modified in the current study.The plasmid shuttle vector was developed by inserting multiple cloning sites,FLAG and HA tags into the shuttle vector by molecular cloning approaches.The target gene was inserted at the site under the control of the promoter (Tn5 derivate) in plasmid pQE30.This promoter contained two lac operators and a codonoptimized lacI gene driven by flaB promoter.Results A plasmid shuttle vector,pJJ275,was successfully constructed with the ability to express target genes in B.burgdorferi in the presence of IPTG.By using this system,a HA-tagged rpoS gene was introduced into the typical infectious strain B.burgdorferi B31.The target gene expression induced by IPTG was confirmed at transcriptional and translational levels.The RpoS dependent virulence factor of Borrelia,OspC,was also detected,indicating that the expressed protein was functional.Conclusion The constructed plasmid shuttle vector can express exogenous genes in B.burgdorferi with an inducible feature and an advantage of flexible genetic manipulation.It can be applied for genetic manipulation of B.burgdorferi involved in gene regulation and complementation.

Objective To evaluate the value of iterative modal reconstruction (IMR) for reducing radiation dose and controlling image quality in cardiac CT. Methods Ten pigs were included. All pigs were scanned on a 256?slice prospectively ECG?gated cardiac CT utilizing routine dose (group A) and tube current reduced by 30%(group B), 50%(group C) and 70%(group D), respectively. Filtered back projection (FBP), hybrid iterative reconstruction (iDose4) and IMR were used for all data, respectively. Image noise and contrast?to?noise ratio (CNR) of ascending aortic root were measured, while overall image quality and coronary artery image quality was rated (five point scale). All results reconstructed by FBP, iDose 4 and IMR were compared. Objective measurements were compared with one?way analysis of variance, and subjective assessments were compared with Kruskal?Wallis H test andχ2 test. Results Compared with that of FBP and iDose4, image noise of IMR was(15.1 ± 6.1),(18.8 ± 5.5),(22.1 ± 4.8)and(33.0 ± 4.0)HU, respectively in group A, B, C and D with significant reduction (F=82.77, 90.71, 96.59, 95.51 respectively, all P<0.01). Using IMR, groups A, B, C, D had higher CNR (42.0±11.1, 37.2±10.4, 31.4±8.7, 23.7±7.0;F=50.65, 53.55, 76.60, 57.36, all P<0.01) and overall image quality (5.0 ± 0.0, 4.8 ± 0.4, 4.6 ± 0.5, 4.5 ± 0.5;H=20.96, 15.63, 18.66, 23.56, all P<0.01) than FBP and iDose4. Using IMR, group A (100%, 40/40) and group B (100%, 40/40) had no significant difference (P>0.05) in the diagnosis rates of proximal coronary arteries compared with that using FBP and iDose4, while group C (100%, 40/40) and group D(92%, 37/40) had significantly increased diagnosis rates (χ2=20.05, 45.72, both P<0.01). The diagnosis rates of distal coronary arteries of IMR reconstruction which were 100%(50/50), 98%(49/50), 90%(45/50), 78%(39/50), respectively in groups A, B, C, D had significant increase compared with that of FBP and iDose4 reconstruction (χ2=7.39, 16.75, 34.62, 81.33, all P<0.05). Conclusions IMR can significantly reduce image noise, improve CNR and image quality compared with iDose4. Application of IMR can reduce radiation dose but without compromising image quality.

BACKGROUND:Mechanical properties of the blood vessels include axial and radial tension which is important to guarantee the tissue perfusion and its pressure. OBJECTIVE:To test and analyze stretching and puncture parameters that can ful y characterize the performance of blood vessels, so as to predict the health condition of the vessels transplanted into recipients. METHODS:Mechanical properties as circumferential tension, axial tension and puncture were tested on the porcine aorta, and then pathological and staining analysis was done to explore whether freeze-dried vessels can withstand the blood pressure in al directions after transplanted into the body. RESULTS AND CONCLUSION:Specific trend on the curves of freeze-dried vessels during circumferential tension, axial tension and puncture process was closer to that of fresh vessel curves, suggesting that structural components and arrangement of the freeze-dried vessels were not changed greatly. Meanwhile, the microscopic observations of slice and tensile section were taken into account so that the reason was studied and explained for the mechanical properties of the experimental data and results. The macroscopic mechanical result was analyzed based on the change of microstructure. These findings indicate that the vacuum freeze-drying is a better method to maintain the performance of blood vessels.

Objective To evaluate the diagnostic value of multi-slice spiral CT (MSCT) in classifying coronary arteries of complete transposition of great arteries (D-TGA). Methods The clinical and imaging data of 367 patients with D-TGA who had undergone MSCT examination from March 2005 to June 2015 were retrospectively analyzed. The origin and course of the coronary arteries of the patients were classified according to the Marie Lannelongue classification. There were four patterns of courses: normal, looping, intramural and miscellaneous. And the four patterns were subdivided into eleven subgroups. The anatomic classification of coronary arteries in D?TGA were recorded, and the ratio of descriptive statistics was used according to categorical variable data. Results All the origin and course of the coronary arteries could be clearly displayed on MSCT. Of 367 patients with D-TGA, 209 cases (56.95%) were normal course (typeⅠ), 138 cases (37.60%) were looping course (typeⅡ), 16 cases (4.36%) were intramural course (typeⅢ), and 4 cases (1.09%) were miscellaneous course (typeⅣ). In looping course, the posterior looping (typeⅡA), anterior looping (typeⅡB) and double looping (typeⅡC) were found in 63 cases (17.17%), 30 cases (8.17%) and 45 cases (12.26%), respectively. The ratios of the anatomic classification of looping courses wereⅡA-1 44(11.99%),ⅡA-2 19(5.18%),ⅡB-1 12(3.27%),ⅡB-2 8(2.18%),ⅡB-3 10(2.72%),ⅡC-1 25 (6.81%),ⅡC-2 17(4.63%),ⅡC-3 3(0.82%). Conclusions MSCT is an effective technique to visualize and classify the coronary arteries in patients with D-TGA. And it is helpful for successful transfer of the coronary arteries and reducing the rate of coronary events after operation.

Objective To evaluate the value of cardiac MRI in the diagnosis of Ebstein anomaly (EA). Methods Twenty patients from February 2014 to April 2017 with EA confirmed by surgery were enrolled into this study. The analysis in all patients was made according to preoperative cardiac MRI, 2D TTE and surgical data, including the changes of tricuspid valve leaflets, Carpentier classification, the size and function of atrioventricle, late Gadolinium enhancement, the total right/left-volume index and cardiopulmonary bypass time,etc.The numbers of apicaldisplaced leaflets and development condition of all the leaflets were compared using the R×C χ2among the three groups.With surgical results as the reference standard, the diagnostic accuracy of the two groups for the development condition of all the leaflets were evaluated. One-way ANOVA was performed to compare the differences of the apicaldisplaced distance of septal leaflet, using these three methods. Comparisons of the total right/left-volume index, surgery-related data between patients with or without late gadolinium enhancement were performed by independent t test.Results (1) The results in anatomicalstructures, such as distance of apicaldisplacedseptal leaflet,displacement of each leaflet and the Carpentier classification, showed nostatistical difference among MRI,2D TTE and operational findings. The leaflet dysplasia defined by MRI and 2D TTE areequivalent to surgically defined severe dysplasia, and surgically defined mild to moderate dysplasia can't be identified by the former two methods. The overall diagnostic accuracy of MRI and 2D TTE to identify leaflet dysplasia were 41.3%(19/46) and 34.7%(16/46), respectively.(2) Functional right ventricular volume index decreased in 1 case, normal in 8 cases, increased in 11 cases;functional right ventricula rejection fraction decreased in 15 cases. Six patients' left ventricular volume index decreased, 13 remained in normal range, 1 showed increased;left ventricula rejection fraction decreased in 14 cases. (3)LGE was identified in 8 patients and non-LGE in 12. Difference of the total right/left-volume index [(7.12 ± 4.06) vs. (3.84 ± 2.10), P=0.029] between two groups was statistically significant. However, there was no statistical difference in extracorporeal circulation time, aorticcross-clamping time, intubation time, ICU residence time and postoperative hospital staybetween the LGE and non-LGE groups.Conclusions Cardiac MRI can relatively accurately evaluate the apicaldisplacement of leaflets and the morphological changes of the atria and ventricles, as well as quantitatively evaluate the ventricular function, which can rovide references for clinical diagnosis and severity evaluation of EA.

Objective To evaluate the accuracy of 3D models of patients with complex congenital heart disease(CHD) printed by domestic 3D priuters based on cardiac CT data.Methods From April 2018 to June 2018,our hospital used domestic 3D printers to print the hearts of 50 patients with complex CHD.The median age of the patients was 24 months(1 month to 61 years),and the diseases included pulmonary atresia,right ventricular double outlet and transposition of aorta.3 measurement sites(150 in total) were selected for each patient.Pearson correlation coefficient calculation,paired t test and Bland-Altman analysis were performed.Results Pearson correlation coefficient is 0.997.The difference of the measured value of CT-model was tested for normality.P was 0.2 of the D test.The Q-Q graph showed that the data point and the theoretical line were highly overlapped.The mean difference was (-0.07 ± 0.67) mm,P =0.196.In Bland-Altman analysis,the consistency boundary value interval of the difference was(-1.29 mm,1.16 mm) between which there were 143/150(95.33％) points.Conclusion 3D models of patients with complex CHD printed by domestic 3D printers based on cardiac CT data have good accuracy.

Objective To evaluate the value of three-dimensional(3 D) printing technique in the diagnosis and treatment of complex congenital heart disease(CHD).Methods From March 2016 to February 2018,40 patients with complex CHD underwent heart CT scanning.The CT images were imported to Standard Template Library(STL) files after 3D reconstruction and then exported for 3D printing.The 3D printed models were then used for decision making and navigation during surgery.Results Thirty patients were indicated for surgical operation.Three patients underwent single ventricular repair,and biventricular repair were operated on 27 patients.The 3D printed models were quite in accordance with the actual anatomical findings in all the patients.And all the procedures carried on were exactly same as planned based on 3D printed model.Conclusion The 3D printing may help improve the diagnosis and treatment level in complex CHD.

Objective:To explore the application value of virtual reality(VR) technology in the surgical diagnosis and treatment of congenital heart disease complicated with ventricular outflow tract stenosis.Methods:From November 2017 to October 2018, a total of 11 cases of congenital heart disease complicated with ventricular outflow tract stenosis were diagnosed and treated by VR technology assisted surgery in our center, including 9 cases of tetralogy of Fallot, 1 case of right ventricular double outlet stenosis and 1 case of right ventricular double outlet complicated with right ventricular outflow tract and pulmonary valve stenosis. The matching degree and value score of VR model by surgeons after operation. The data of these cases, including postoperative severe complications, maximum flow velocity and peak pressure difference and left ventricular ejection fraction(LVEF) 3 months after surgery, were retrospectively analyzed to evaluate the application value of VR technology and summarize the application experience of our center.Results:The operations were successful in all the 11 cases with no death in hospital. No serious complications related to the ventricular outflow tract occurred after the operation. The peak systolic velocity of the ventricular outflow tract in all the patients decreased to less than 2 m/s, and LVEF was in the normal range three months after the operation. In terms of VR model scores, the matching degree of all cases was 8/10 or above and 8 patients received a 3/3 of value score.Conclusion:For patients with congenital heart disease complicated with ventricular outflow tract stenosis, VR technology based on CT three-dimensional reconstruction can help surgeons more intuitively understand the spatial location information of each intra- and extra-cardiac structure and evaluate the feasibility of key surgical procedures, which is conducive to individual surgery and guarantees a good surgical outcome.

Objective To analyze the application of virtual reality technology and mixed reality techniques in our hospital before and during intraoperative evaluation of complicated congenital heart diseases .Methods Methods Retrospectively ana-lyze the clinical treatment, surgical decision-making, intraoperative and early prognosis of 11 children with complicated congen-ital heart disease assessed by virtual reality technology and mixed reality techniques.The time of operation was 34-121 min, CPB time was 26-101 min, the clamping time of aorta was 18-56 min.There was no operative death.Results All 11cases were assessed by virtual reality technology and mixed reality technology before surgery .Personalized surgical strategies were made based on the evaluation results.All patients had undergone operations successfully.Compared with traditional surgical methods, fewer surgical incisions and shorter operation time were required.And it improved the surgical results.Conclusion Virtual reality technology and mixed reality technology have a great advantage in preoperative and intraoperative evaluation of complex congenital heart diseases.They can optimize surgical strategies, shorten operation time, and reduce surgical trauma. They are worthy of further promotion and application in clinical practice.

Objective To evaluate the application of three-dimensional printing technique in surgical treatments on complex congenital heart diseases. Methods Two patients were enrolled with complex congenital heart diseases. The computerized tomography data were used to build the 3D architecture of cardiac anomalies. The White-Jet-Process technique was used to print the models with 1∶1 ratio in size. The models were used to make the treatment strategy making, young surgeon training and operation simulation. Results The full color and hollowed-out cardiac models with 1∶1 ration in size were printed successfully. They were transected at the middle point of vertical axis, which was conveniently to explore the intracardiac anomalies. However, for patient 1, the model lost the atrial septal defect. Taking the two models as references, operation group held preoperative consultation, operation simulation, and finally, the operation plans were determined for the two patients. Both the two operation were carried out smoothly. Conclusion Although the limitations of 3D printing still exist in the application for congenital heart diseases, making the preoperative plan and operation simulation via 3D cardiac model could enhance the understanding of following operation and procedure details, which could improve the tacit cooperation among operation group members. Furthermore, operation results also could be improved potentially. Therefore, the cardiac 3D printing should be popularized in clinic in the future.