Optimization of tracheoesophageal fistula model established with Tshaped magnet system based on magnetic compression technique

BACKGROUND The magnetic compression technique has been used to establish an animal model of tracheoesophageal fistula(TEF),but the commonly shaped magnets present limitations of poor homogeneity of TEF and poor model control.We designed a Tshaped magnet system to overcome these problems and verified its effectiveness via animal experiments.AIM To investigate the effectiveness of a T-shaped magnet system for establishing a TEF model in beagle dogs.METHODS Twelve beagles were randomly assigned to groups in which magnets of the Tshaped scheme(study group,n=6)or normal magnets(control group,n=6)were implanted into the trachea and esophagus separately under gastroscopy.Operation time,operation success rate,and accidental injury were recorded.After operation,the presence and timing of cough and the time of magnet shedding were observed.Dogs in the control group were euthanized after X-ray and gastroscopy to confirm establishment of TEFs after coughing,and gross specimens of TEFs were obtained.Dogs in the study group were euthanized after X-ray and gastroscopy 2 wk after surgery,and gross specimens were obtained.Fistula size was measured in all animals,and then harvested fistula specimens were examined by hematoxylin and eosin(HE)and Masson trichrome staining.RESULTS The operation success rate was 100%for both groups.Operation time did not differ between the study group(5.25 min±1.29 min)and the control group(4.75 min±1.70 min;P=0.331).No bleeding,perforation,or unplanned magnet attraction occurred in any animal during the operation.In the early postoperative period,all dogs ate freely and were generally in good condition.Dogs in the control group had severe cough after drinking water at 6-9 d after surgery.X-ray indicated that the magnets had entered the stomach,and gastroscopy showed TEF formation.Gross specimens of TEFs from the control group showed the formation of fistulas with a diameter of 4.94 mm±1.29 mm(range,3.52-6.56 mm).HE and Masson trichrome staining showed scar tissue formation and hierarchical structural disorder at the fistulas.Dogs in the study group did not exhibit obvious coughing after surgery.X-ray examination 2 wk after surgery indicated fixed magnet positioning,and gastroscopy showed no change in magnet positioning.The magnets were removed using a snare under endoscopy,and TEF was observed.Gross specimens showed well-formed fistulas with a diameter of 6.11 mm±0.16 mm(range,5.92-6.36 mm),which exceeded that in the control group(P<0.001).Scar formation was observed on the internal surface of fistulas by HE and Masson trichrome staining,and the structure was more regular than that in the control group.CONCLUSION Use of the modified T-shaped magnet scheme is safe and feasible for establishing TEF and can achieve a more stable and uniform fistula size compared with ordinary magnets.Most importantly,this model offers better controllability,which improves the flexibility of follow-up studies.

Y–Z deformable magnetic ring for the treatment of rectal stricture: A case report and review of literature

BACKGROUND Treatment of postoperative anastomotic stenosis for colorectal cancer is often challenging,especially for patients who do not respond well to endoscopy.In cases where patients have undergone an enterostomy,the stenosis can be easily resolved through magnetic compression.However,common magnetic compre-ssion techniques cannot be performed on those without enterostomy.We design-ed a novel Y–Z deformable magnetic ring(Y–Z DMR)and successfully applied it to a patient with a stenosis rectal anastomosis and without enterostomy after rectal cancer surgery.CASE SUMMARY We here report the case of a 57-year-old woman who had undergone a laparo-scopic radical rectum resection(Dixon)for rectal cancer.However,she started facing difficulty in defecation 6 months after surgery.Her colonoscopy indicated stenosis of the rectal anastomosis.Endoscopic balloon dilation was performed six times on her.However,the stenosis still showed a trend of gradual aggravation.Because the patient did not undergo an enterostomy,the conventional endoscopic magnetic compression technique could not be performed.Hence,we imple-mented a Y–Z DMR implemented through the anus under single channel.The magnetic ring fell off nine days after the operation and the rectal stenosis was relieved.The patient was followed up for six months and reported good defeca-tion.CONCLUSION The Y–Z DMR deformable magnetic ring is an excellent treatment strategy for patients with rectal stenosis and without enterostomy.

Magnetic compression anastomosis to restore biliary tract continuity after obstruction following major abdominal trauma:A case report

BACKGROUND The combination of magnetic compression anastomosis(MCA)and endoscopy has been used to treat biliary stricture after liver transplantation.However,its use for the treatment of complex biliary obstruction after major abdominal trauma has not been reported.This case report describes the successful use of MCA for the treatment of biliary obstruction resulting from major abdominal trauma.A 23-year-old man underwent major abdominal surgery(repair of liver rupture,right half colon resection,and ileostomy)following a car accident one year ago.The abdominal drainage tube,positioned at the Winslow foramen,was draining approximately 600-800 mL of bile per day.During the two endoscopic retrograde cholangiopancreatography procedures,the guide wire was unable to enter the common bile duct,which prevented placement of a biliary stent.MCA combined with endoscopy was used to successfully achieve magnetic anastomosis of the peritoneal sinus tract and duodenum,and then a choledochoduodenal stent was placed.Finally,the external biliary drainage tube was removed.The patient achieved internal biliary drainage leading to the removal of the external biliary drainage tube,which improved the quality of life.CONCLUSION Magnetic compression technique can be used for the treatment of complex biliary obstruction with minimal operative trauma.

Novel magnetic compression technique for the treatment of postoperative anastomotic stenosis in rectal cancer:A case report

BACKGROUND The treatment of postoperative anastomotic stenosis after excision of rectal cancer is challenging.Endoscopic balloon dilation and radial incision are not effective in all patients.We present a new endoscopy-assisted magnetic compression technique(MCT)for the treatment of rectal anastomotic stenosis.We successfully applied this MCT to a patient who developed an anastomotic stricture after radical resection of rectal cancer.A 50-year-old man had undergone laparoscopic radical rectal cancer surgery at a local hospital 5 months ago.A colonoscopy performed 2 months ago indicated that the rectal anastomosis was narrow due to which ileostomy closure could not be performed.The patient came to the Magnetic Surgery Clinic of the First Affiliated Hospital of Xi'an Jiaotong University after learning that we had successfully treated patients with colorectal stenosis using MCT.We performed endoscopy-assisted magnetic compression surgery for rectal stenosis.The magnets were removed 16 d later.A follow-up colonoscopy performed after 4 months showed good anastomotic patency,following which,ileostomy closure surgery was performed.CONCLUSION MCT is a simple,non-invasive technique for the treatment of anastomotic stricture after radical resection of rectal cancer.The technique can be widely used in clinical settings.

Treatment of anastomotic stricture after rectal cancer operation by magnetic compression technique:A case report

BACKGROUNDThe treatment of postoperative anastomotic stenosis(AS)after resection of colorectalcancer is challenging.Endoscopic balloon dilation is used to treat stenosisin such cases,but some patients do not show improvement even after multipleballoon dilations.Magnetic compression technique(MCT)has been used for gastrointestinalanastomosis,but its use for the treatment of postoperative AS aftercolorectal cancer surgery has rarely been reported.CASE SUMMARYWe report a 72-year-old man who underwent radical resection of colorectal cancerand ileostomy one year ago.An ileostomy closure was prepared six months ago,but colonoscopy revealed a narrowing of the rectal anastomosis.Endoscopic balloondilation was performed three times,but colonoscopy showed no significantimprovement in stenosis.The AS was successfully treated using MCT.CONCLUSIONMCT is a minimally invasive method that can be used for the treatment of postoperativeAS after colorectal cancer surgery.

Influence of different magnetic forces on the effect of colonic anastomosis in rats

BACKGROUND Despite much work having been conducted on magnetic compression anastomo-sis(MCA)in the digestive tract,there are no reports on the influence of magnetic force on the anastomosis.AIM To investigate the effect of different magnetic force magnets on the MCA of the digestive tract.METHODS Two groups of magnets of the same sizes but different magnetic forces were designed and produced.A total of 24 Sprague-Dawley rats were randomly assigned into two groups(powerful magnet group and common magnet group),with 12 rats in each group.Two types of magnets were used to complete the colonic side-to-side anastomosis of the rats.The operation time and magnet discharge time were recorded.The anastomotic specimens were obtained 4 wk after the operation and then the burst pressure and diameter of the anastomosis were measured,and the anastomosis was observed via the naked eye and subjected to histological examination.RESULTS The magnetic forces of the powerful and common magnet groups at zero distance were 8.26 N and 4.10 N,respectively.The colonic side-to-side anastomosis was completed in all 24 rats,and the operation success rate and postoperative survival rate were 100%.No significant difference was noted in the operation time between the two groups.The magnet discharge time of the powerful magnet group was slightly longer than that of the common magnet group,but the difference was not statistically significant(P=0.513).Furthermore,there was no statistical difference in the burst pressure(P=0.266)or diameter of magnetic anastomosis(P=0.095)between the two groups.The gross specimens of the two groups showed good anastomotic healing,and histological observation indicated good mucosal continuity without differences on healing.CONCLUSION In the rat colonic side-to-side MCA model,both the powerful magnet with 8.26 N and the common magnet with 4.10 N showed no significant impact on the anastomosis establishment process or its effect.

Clinical feasibility of laparoscopic left lateral segment liver resection with magnetic anchor technique:The first clinical study from China

BACKGROUND Magnetic anchor technique(MAT)has been applied in laparoscopic cholecystectomy and laparoscopic appendectomy,but has not been reported in laparoscopic partial hepatectomy.AIM To evaluate the feasibility of the MAT in laparoscopic left lateral segment liver resection.METHODS Retrospective analysis was conducted on the clinical data of eight patients who underwent laparoscopic left lateral segment liver resection assisted by MAT in our department from July 2020 to November 2021.The Y-Z magnetic anchor devices(Y-Z MADs)was independently designed and developed by the author of this paper,which consists of the anchor magnet and magnetic grasping apparatus.Surgical time,intraoperative blood loss,intraoperative accidents,operator experience,postoperative incision pain score,postoperative complications,and other indicators were evaluated and analyzed.RESULTS All eight patients underwent a MAT-assisted laparoscopic left lateral segment liver resection,including three patients undertaking conventional 5-port and five patients having a transumbilical single-port operation.The mean operation time was 138±34.32 min(range 95-185 min)and the mean intraoperative blood loss was 123±88.60 mL(range 20-300 mL).No adverse events occurred during the operation.The Y-Z MADs showed good workability and maneuverability in both tissue and organ exposure.In particular,the operators did not experience either a“chopstick”or“sword-fight”effect in the single-port laparoscopic operation.CONCLUSION The results show that the MAT is safe and feasible for laparoscopic left lateral segment liver resection,especially,exhibits its unique abettance for transumbilical single-port laparoscopic left lateral segment liver resection.

Magnetic compression anastomosis for reconstruction of digestive tract after total gastrectomy in beagle model

BACKGROUND Magnetic compression anastomosis(MCA)is a simple procedure contributing to a reliable anastomosis.However,digestive-tract reconstruction after total gastrectomy using MCA has not yet been reported.AIM To investigate the feasibility of MCA for simultaneous esophagojejunostomy and jejunojejunostomy after total gastrectomy using beagle dogs.METHODS Sixteen beagles were randomly divided into an MCA group(study group,n=8)and a manual-suture anastomosis group(control group,n=8).Two different magnetic anastomosis devices were used in the study group for esophagojejunal and jejunojejunal anastomoses.Both devices included a pair of circular daughter and parent magnets each.The time of esophagojejunostomy and jejunojejunostomy,postoperative complications,and survival rate of the two groups were compared.The dogs were sacrificed one month after the operation and their anastomotic specimens were obtained.Healing was observed by the naked eye and a light microscope.RESULTS Digestive-tract reconstruction after total gastrectomy was successfully completed in both groups(survival rate=100%).In the study group,esophagojejunal and jejunojejunal anastomoses took 6.13±0.58 and 4.06±0.42 min,respectively,significantly lower than those in the control group(15.63±1.53 min,P<0.001 and 10.31±1.07 min,P<0.001,respectively).Complications such as bleeding,anastomotic leakage,and anastomotic stenosis were not observed.In the study group,the magnets did not interfere with each other.Discharge time of the jejunojejunal magnetic anastomosis device was 10.75±1.28 d,while that of the esophagojejunal magnetic anastomosis device was 12.25±1.49 d.Residual silk was found in the control group.The study group showed a greater smoothness of the anastomosis than that of the control group.All layers of anastomosis healed well in both groups.CONCLUSION MCA is a safe and feasible procedure for digestive-tract reconstruction after total gastrectomy in this animal model.

Magnetic compression anastomosis for sigmoid stenosis treatment:A case report

BACKGROUND Endoscopic balloon dilation is a minimally invasive treatment for colorectal stenosis.Magnetic compression anastomosis can be applied against gastrointestinal anastomosis.When combined with endoscopy,it offers a unique approach to the recanalization of colorectal stenosis.CASE SUMMARY We have reported here the case of a 53-year-old female patient who underwent a descending colostomy due to sigmoid obstruction.Postoperative fistula restoration was not possible in her due to sigmoid stenosis.Accordingly,endoscopicassisted magnetic compression anastomosis for sigmoid stenosis was performed,and the sigmoid stenosis was recanalized 15 d after the surgery.Subsequently,a reduction colostomy was successfully performed after 10 d.CONCLUSION This case report proposes a novel minimally invasive treatment approach for colorectal stenosis.

Animal experimental study on magnetic anchor technique-assisted endoscopic submucosal dissection of early gastric cancer

BACKGROUND Gastric cancer(GC)has high morbidity and mortality.Moreover,because GC has no typical symptoms in the early stages,most cases are already in the advanced stages by the time the symptoms appear,thus resulting in poor prognosis and a low survival rate.Endoscopic submucosal dissection(ESD)can realize the early detection and diagnosis of GC and become the main surgical method for early GC.However,ESD has a steep learning curve and high technical skill requirements for endoscopists,which is not conducive to its widespread implementation and advancement.Therefore,a series of auxiliary techniques have been derived.AIM To evaluate the safety and efficacy of magnetic anchor technique(MAT)-assisted ESD in early GC.METHODS This was an ex vivo animal experiment.The experimental models were the isolated stomachs of pigs,which were divided into two groups,namely the study group(n=6)with MAT-assisted ESD and the control group(n=6)with traditional ESD.Comparing the total surgical time,incidence of surgical complications,complete mucosal resection rate,specimen size,and the scores of endoscopist’s satisfaction with the procedure reflected their feelings about convenience during the surgical procedure between the two groups.The magnetic anchor device for auxiliary ESD in the study group comprised three parts,an anchor magnet(AM),a target magnet(TM),and a soft tissue clip.Under gastroscopic guidance,the soft tissue clip and the TM were delivered to the pre-marked mucosal lesion through the gastroscopic operating hole.The soft tissue clip and the TM were connected by a thin wire through the TM tail structure.The soft tissue clip was released by manipulating the operating handle of the soft tissue clip in a way that the soft tissue clip and the TM were fixed to the lesion mucosa.In vitro,ESD is aided by maneuvering the AM such that the mucosal dissection surface is exposed.RESULTS The total surgical time was shorter in the study group than in the control group(26.57±0.19 vs 29.97±0.28,P<0.001),and the scores of endoscopist’s satisfaction with the procedure were higher in the study group than in the control group(9.53±0.10 vs 8.00±0.22,P<0.001).During the operation in the study group,there was no detachment of the soft tissue clip and TM and no mucosal tearing.The magnetic force between the AM and TM provided good mucosal exposure and sufficient tissue tension for ESD.The mucosal lesion was completely peeled off,and the operation was successful.There were no significant differences in the incidence of surgical complications(100%vs 83.3%),complete mucosal resection rate(100%vs 66.7%,P=0.439),and specimen size(2.44±0.04 cm vs 2.49±0.02,P=0.328)between the two groups.CONCLUSION MAT-ESD is safe and effective for early GC.It provides a preliminary basis for subsequent internal animal experiments and clinical research.

Novel deformable self-assembled magnetic anastomosis ring for endoscopic treatment of colonic stenosis via natural orifice

BACKGROUND Although endoscope-assisted magnetic compression anastomosis has already been reported for colonic anastomosis,there is no report on a single-approach operation using the natural orifice.AIM To design a deformable self-assembled magnetic anastomosis ring(DSAMAR)for colonic anastomosis for use in single-approach operation and evaluate its feasibility and safety through animal experiments.METHODS The animal model for colonic stenosis was prepared by partial colonic ligation in eight beagles.The magnetic compression anastomosis of their colonic stricture was performed by endoscopically assisted transanal implantation of the DSAMAR.The anastomotic specimen,obtained 2 wk after the operation,was observed by both the naked eye and a light microscope.RESULTS The DSAMAR was successfully inserted into the proximal end of colon stenosis through the anus.The DSAMAR of seven dogs was successfully transformed into rings,while that of the remaining dog was removed after the first deformation failed.The rings were successfully retransformed after optimization.All animals underwent colonic anastomosis using the DSAMAR.No device-related or procedure-related adverse events were observed.The colostomy specimens of the experimental dogs were obtained 2 wk after the operation.Both gross and histological observations showed good anastomotic healing.CONCLUSION The DSAMAR is a safe and feasible option for the treatment of colon stenosis.Its specific deformation and selfassembly capability maximize the applicability of the minimally invasive treatment.

Primary animal experiment to test the feasibility of a novel Y-Z magnetic hepatic portal blocking band

BACKGROUND Hepatic portal blood flow occlusion is a common technique for reducing hepatic hemorrhage during hepatectomy.We designed a novel Y-Z magnetic hepatic portal blocking band(Y-Z MHPBB)based on the principle of magnetic compression technique.AIM To introduce the Y-Z MHPBB device and verify the feasibility of this device for hepatic portal blood flow occlusion in dogs.METHODS Ten beagles were randomly divided into the experimental group and control group.The operation time,intraoperative blood loss,the number of portal blood flow occlusions,the total time spent on adjusting the blocking band,and the average time spent on adjusting the blocking band were recorded.The surgeons evaluated the feasibility and flexibility of the two portal occlusion devices.RESULTS Laparoscopic hepatectomy was successfully performed in both the experimental group and control group.There was no statistical difference between the two groups in the operation time,intraoperative blood loss,and the number of hepatic portal blood flow occlusions.With respect to the total time spent on adjusting the blocking band and the average time spent on adjusting the blocking band,the experimental group showed significantly better outcomes than the control group,with a statistical difference(P<0.05).The operators found that the Y-Z MHPBB was superior to the modified T-tube in terms of operational flexibility.CONCLUSION The Y-Z MHPBB seems to be an ingenious design,accurate blood flow occlusion effect,and good flexibility;and it can be used for hepatic portal blood flow occlusion during laparoscopic hepatectomy.

Magnetic anchor technique assisted endoscopic submucosal dissection for early esophageal cancer

BACKGROUND Esophageal cancer has high incidence globally and is often diagnosed at an advanced stage.With the widespread application of endoscopic technologies,the need for early detection and diagnosis of esophageal cancer has gradually been realized.Endoscopic submucosal dissection(ESD)has become the standard of care for managing early tumors of the esophagus,stomach,and colon.However,due to the steep learning curve,difficult operation,and technically demanding nature of the procedure,ESD has currently been committed to the development of various assistive technologies.AIM To explore the feasibility and applicability of magnetic anchor technique(MAT)-assisted ESD for early esophageal cancer.METHODS Isolated pig esophagi were used as the experimental model,and the magnetic anchor device was designed by us.The esophagi used were divided into two groups,namely the operational and control groups,and 10 endoscopists completed the procedure.The two groups were evaluated for the following aspects:The total operative time,perforation rate,rate of whole mucosal resection,diameter of the peering mucosa,and scores of endoscopists’feelings with the procedure,including the convenience,mucosal surface exposure degree,and tissue tension.In addition,in the operational group,the soft tissue clip and the target magnet(TM)were connected by a thin wire through a small hole at the tail end of the TM.Under gastroscopic guidance,the soft tissue clip was clamped to the edge of the lesioned mucosa,which was marked in advance.By changing the position of the anchor magnet(AM)outside the esophagus,the pulling force and pulling direction of the TM could be changed,thus exposing the mucosal peeling surface and assisting the ESD.RESULTS Herein,each of the two groups comprised 10 isolated esophageal putative mucosal lesions.The diameter of the peering mucosa did not significantly differ between the two groups(2.13±0.06 vs 2.15±0.06,P=0.882).The total operative time was shorter in the operational group than in the control group(17.04±0.22 min vs 21.94±0.23 min,P<0.001).During the entire experiment,the TM remained firmly connected with the soft tissue clip and did not affect the opening,closing,and release of the soft tissue clip.The interaction between the TM and AM could provide sufficient tissue tension and completely expose the mucosa,which greatly assists the surgeon with the operation.There was no avulsion of the mucosa,and mucosal lesions were intact when peeled.Therefore,the scores of endoscopists’feelings were higher in the operational group than in the control group in terms of the convenience(9.22±0.19 vs 8.34±0.15,P=0.002),mucosal surface exposure degree(9.11±0.15 vs 8.25±0.12,P<0.001),and tissue tension(9.35±0.13 vs 8.02±0.17,P<0.001).The two groups did not significantly differ in the perforation rate and rate of whole mucosal resection.CONCLUSION We found MAT-assisted ESD safe and feasible for early esophageal cancer.It could greatly improve the endoscopic operation experience and showed good clinical application prospects.

Lipidomic and transcriptomic analysis reveals reallocation of carbon flux from cuticular wax into plastid membrane lipids in a glossy“Newhall”navel orange mutant

Both cuticle and membrane lipids play essential roles in quality maintenance and disease resistance in fresh fruits.Many reports have indicated the modification of alternative branch pathways in epicuticular wax mutants;however,the specific alterations concerning lipids have not been clarified thus far.Here,we conducted a comprehensive,timeresolved lipidomic,and transcriptomic analysis on the“Newhall”navel orange(WT)and its glossy mutant(MT)“Gannan No.1”.The results revealed severely suppressed wax formation accompanied by significantly elevated production of 36-carbon plastid lipids with increasing fruit maturation in MT.Transcriptomics analysis further identified a series of key functional enzymes and transcription factors putatively involved in the biosynthesis pathways of wax and membrane lipids.Moreover,the high accumulation of jasmonic acid(JA)in MT was possibly due to the need to maintain plastid lipid homeostasis,as the expression levels of two significantly upregulated lipases(CsDAD1 and CsDALL2)were positively correlated with plastid lipids and characterized to hydrolyze plastid lipids to increase the JA content.Our results will provide new insights into the molecular mechanisms underlying the natural variation of plant lipids to lay a foundation for the quality improvement of citrus fruit.

Diagnosis and treatment of acute graft-versus-host disease after liver transplantation:Report of six cases

BACKGROUND Graft-versus-host disease(GVHD)following liver transplantation(LT)is an unpredictable complication with poor outcome.However,consensus regarding the diagnosis and therapeutic regimen for the disease is yet lacking.The present study summarized the clinical experience on the diagnosis and treatment of acute GVHD(aGVHD)following LT and reviewed the pertinent literature.CASE SUMMARY Between January 1^(st),2000 and December 31^(st),2020,a total of 1053 LT were performed in the First Affiliated Hospital of Xi’an Jiaotong University.Six recipients developed aGVHD with clinical symptoms of fever,rash,diarrhea,and pancytopenia.The incidence of aGVHD was 0.57%.The median time from LT to the clinical presentation of aGVHD was 22.17 d.The median time from the beginning of the clinical symptom to histopathological diagnosis was 7.5 d.All six cases underwent treatment of immunosuppressant adjustment,corticosteroids,human normal immunoglobulin,and antithymocyte globulin/IL-2 antagonists.Despite intensive treatment strategies,4 patients were deceased due to sepsis,multiple organ failure,and cerebral hemorrhage.The remaining two cases were discharged as treatment successfully.However,one died because of tuberculosis infection on the 6 th month of follow-up,the other one was alive healthy during 30 mo of follow-up.CONCLUSION The rapid diagnosis of aGVHD is mainly based on the time from the first symptom,histopathological features,and the donor T-lymphocyte chimerism.Our cases report highlights massive corticosteroid therapy and age difference between donors and recipients could accelerate to aGVHD.Moreover,gut microbial interventions and donor-targeted serotherapy may provide novel therapeutics.

磁压榨吻合技术治疗结直肠吻合及重建中的应用分析

回顾磁压榨吻合技术(magnetic compression anastomosis,MCA)治疗不同原因、不同类型肠道狭窄/闭锁实现肠道再通的案例,对MCA在结直肠吻合及重建中的临床应用进行分析探讨。4例患者2019年5月—2022年8月在西安交通大学第一附属医院及西北妇女儿童医院行结直肠MCA再通治疗。患者手术过程均顺利,实现肠道吻合再通,磁环排出时间为7~15 d,术后复查肠镜或造影提示吻合口完好。MCA可用于治疗不同原因、不同类型的结直肠狭窄及闭锁,也可用于辅助结直肠手术肠吻合。

Numerical simulation investigation on hydration heat temperature and early cracking risk of concrete box girder in cold regions

The temperature change caused by hydration leads to early-age cracking in concrete box girder.The early-age cracking risk is further improved with low air temperature and large daily temperature difference,especially in Northwest China.To fill this gap,a temperature experiment and numerical simulation were performed on an actual concrete box girder segment in Northwest China.The temperature field,thermal stress and cracking risk were analyzed using evolution curves,distribution curves and contours.The key parameters that influence the hydration heat temperature,including the cement hydration heat release,cement content,height-width ratio of web,initial temperature,convective coefficient of top plate surface,were analyzed.An anti-cracking case based on parameters analysis was put forward.The results indicated that the temperature evolution can be divided into three stages:warming,cooling and environment significantly impacting.Along the thickness of each plate,temperature distributed is single peak in the center.Along the width or height,temperature distributed is double peaks at axillary position for the top and bottom plates,and single peak in center for the web.The axillary position and web have high thermal stress and significant cracking risks.The temperature difference of each plate,and the early-age cracking risk can be reduced by effectively adjusting the key parameters.Among these,the former two parameters are the most significant factors.The maximum cracking risk can be decreased by 15.7%for every 50 kJ/kg hydration heat reduction.The maximum cracking risk can be decreased by 13.1%for every 50 kg/m^(3)cement content reduction.

Clinical effect of magnetic compression anastomosis on ureterostenosis after kidney transplantation

To the Editor:Ureterostenosis is one of the most common complications after kidney transplantation,with an incidence rate of 1.0–8.3%according to a relevant report.[1,2]This complication may cause postrenal obstruction,affecting the function of the transplanted kidney and increasing the risk of kidney loss.

Temperature action and effect of concrete-filled steel tubular bridges:A review

Concrete-filled steel tube(CFST)has been widely applied in bridges due to its excellent structural and constructional performance.In CFST bridges,temperature action is not only an important but also a special load that must be considered in bridge design,construction and structural evaluation.This paper presents an overview on current researches of the temperature action and effect of CFST bridges.The historical and spatial characteristics as well as corresponding influencing factors of temperature distributions are summarized,and classifications of temperature actions are also reviewed.Results show that in-depth investigations of the contributions of temperature influencing factors can help to effectively reduce the adverse temperature effects on CFST bridges in the design stage.Due to the lack of long-term measurements and insufficient use of historical meteorological data,research on the representative value along with correlation analysis of CFST temperature actions and meteorological parameters have to be further carried out.In the meanwhile,a decomposition method of temperature distribution is proposed based on structural effects of CFST bridges in this paper.The decomposed temperature actions can be used for more accurate effect calculation than traditional temperature action classification method,especially for CFST truss bridges.At last,specific temperature action patterns still need to be investigated in some of the special problems,such as longitudinal temperature differences along the CFST arch rib and thermal debonding in the CFST interface.Further investigations are required on the accurate simulation of temperature distribution of CFST bridges considering the shading effects of components and terrain.

Clinical and Genetic Investigation of a Multi-generational Chinese Family Afflicted with Von Hippel-Lindau Disease

Background：Von Hippel-Lindau （VHL） disease is a hereditary tumor disorder caused by mutations or deletions of the VHL gene.Few studies have documented the clinical phenotype and genetic basis of the occurrence of VHL disease in China.This study armed to present clinical and genetic analyses of VHL within a five-generation VHL family from Northwestern China,and summarize the VHL mutations and clinical characteristics of Chinese families with VHL according to previous studies.Methods：An epidemiological investigation of family members was done to collect the general information.A retrospective study of clinical VHL cases was launched to collect the relative clinical data.Genetic linkage and haplotype analysis were used to make sure the linkage of VHL to disease in this family.The VHL gene screening was performed by directly analyzing DNA sequence output.At last,we summarized the VHL gene mutation in China by the literature review.Results：A five-generation North-western Chinese family afflicted with VHL disease was traced in this research.The family consisted of 38 living family members,of whom nine were affected.The individuals afflicted with VHL exhibited multi-organ tumors that included pheochromocytomas （8）,central nervous system hemangioblastomas （3）,pancreatic endocrine tumors （2）,pancreatic cysts （3）,renal cysts （4）,and paragangliomas （2）.A linkage analysis resulted in a high maximal LOD score of 8.26 （theta =0.0） for the marker D3S1263,which is in the same chromosome region as VHL.Sequence analysis resulted in the identification of a functional C〉T transition mutation （c.499 C〉T,p.R167W） located in exon 3 of the 16th codon of VHL.All affected individuals shared this mutation,whereas the unaffected family members and an additional 100 unrelated healthy individuals did not.To date,49 mutations have been associated with this disease in Chinese populations.The most frequent VHL mutations in China are p.S65 W,p.N78 S,p.R161Q and p.R167 W.Conclusions：The results supported the notion that the genomic sequence that corresponds to the 167th residue of VHL is a mutational hotspot.Further research is needed to clarify the molecular role of VHL in the development of organ-specific tumors.