BACKGROUND:Oral submucous fibrosis is a chronic progressive disease that is prone to malignant transformation.Traditional treatment methods are not ideal and have limitations.As an emerging discipline,tissue engineering has opened up a new path for the treatment of oral submucous fibrosis.OBJECTIVE:To review the latest progress in the pathogenesis and treatment of oral submucous fibrosis,and to summarize and analyze the role and research progress of mesenchymal stem cells,bioscaffold materials,and tissue-engineered oral mucosa in oral submucous fibrosis,thereby providing ideas for the research and clinical application of tissue engineering in the treatment of oral submucous fibrosis.METHODS:In October 2024,the first author used computers to search for relevant literature from January 1970 to October 2024 in PubMed and CNKI databases.The search terms were"oral submucous fibrosis,tissue engineering,mesenchymal stem cells,bioscaffold materials"in English and Chinese,respectively.A total of 166 articles were finally included for analysis.RESULTS AND CONCLUSION:(1)The pathogenesis of oral submucous fibrosis is complex,and many factors are closely related to oral submucous fibrosis,but ultimately they promote the development of oral submucous fibrosis by promoting collagen deposition and accelerating fibroblast proliferation.(2)Traditional treatment methods for oral submucous fibrosis have problems such as low patient compliance and unsatisfactory results,and new treatment strategies are urgently needed.(3)Mesenchymal stem cells regulate the pathological microenvironment,reduce inflammation and inhibit the process of fibrosis due to their immunomodulatory and antioxidant properties,providing a new idea for the treatment of oral submucous fibrosis.(4)Biomass materials,as drug and cell delivery carriers,regulate the pathological microenvironment and are used in various fibrotic diseases,providing a new solution for the treatment of oral submucous fibrosis.(5)Tissue-engineered oral mucosa can be used as an autologous mucosa substitute to promote tissue repair,and also provides a basis for the establishment of disease models.(6)Tissue engineering treatment strategy has great potential for achieving comprehensive treatment of oral submucous fibrosis,but its role in the treatment of oral submucous fibrosis has not yet been verified.It is of great significance to explore tissue engineering-based treatment strategies for oral submucous fibrosis in the future.

BACKGROUND:Oral submucous fibrosis is a chronic progressive disease that is prone to malignant transformation.Traditional treatment methods are not ideal and have limitations.As an emerging discipline,tissue engineering has opened up a new path for the treatment of oral submucous fibrosis.OBJECTIVE:To review the latest progress in the pathogenesis and treatment of oral submucous fibrosis,and to summarize and analyze the role and research progress of mesenchymal stem cells,bioscaffold materials,and tissue-engineered oral mucosa in oral submucous fibrosis,thereby providing ideas for the research and clinical application of tissue engineering in the treatment of oral submucous fibrosis.METHODS:In October 2024,the first author used computers to search for relevant literature from January 1970 to October 2024 in PubMed and CNKI databases.The search terms were"oral submucous fibrosis,tissue engineering,mesenchymal stem cells,bioscaffold materials"in English and Chinese,respectively.A total of 166 articles were finally included for analysis.RESULTS AND CONCLUSION:(1)The pathogenesis of oral submucous fibrosis is complex,and many factors are closely related to oral submucous fibrosis,but ultimately they promote the development of oral submucous fibrosis by promoting collagen deposition and accelerating fibroblast proliferation.(2)Traditional treatment methods for oral submucous fibrosis have problems such as low patient compliance and unsatisfactory results,and new treatment strategies are urgently needed.(3)Mesenchymal stem cells regulate the pathological microenvironment,reduce inflammation and inhibit the process of fibrosis due to their immunomodulatory and antioxidant properties,providing a new idea for the treatment of oral submucous fibrosis.(4)Biomass materials,as drug and cell delivery carriers,regulate the pathological microenvironment and are used in various fibrotic diseases,providing a new solution for the treatment of oral submucous fibrosis.(5)Tissue-engineered oral mucosa can be used as an autologous mucosa substitute to promote tissue repair,and also provides a basis for the establishment of disease models.(6)Tissue engineering treatment strategy has great potential for achieving comprehensive treatment of oral submucous fibrosis,but its role in the treatment of oral submucous fibrosis has not yet been verified.It is of great significance to explore tissue engineering-based treatment strategies for oral submucous fibrosis in the future.

Objective:To explore the clinical characteristics and identification of the independent risk factors for disease progression in patients with anti-gp210 antibody-positive primary biliary cholangitis (PBC).Methods:A retrospective cohort study was performed. A total of 323 cases with PBC diagnosed in Tianjin Medical University General Hospital from January 2013 to June 2023 (125 patients with anti-gp210 antibody-positive and 198 patients with anti-gp210 antibody-negative) were included. Baseline and follow-up data were collected. The independent sample t-test and Mann-Whitney U rank sum test were used for comparison between groups of continuous data. The χ2 test was used to compare the data between groups for the count data. The Pearson test was used for correlation analysis between continuous variables. The Kaplan-Meier method was used to analyze the disease progression-free survival rate. The Cox regression model was used to analyze the risk factors for disease progression. Results:The male proportion (11.2% vs. 5.1%, P=0.040) and IgM level [3.29(1.88, 4.80) g/L vs. 2.56(1.44, 3.87) g/L, P=0.019] were significantly higher in patients with PBC with positive anti-gp210 antibodies than those of the negative group. Histopathological analysis showed that the Scheuer score [1(0,3) vs. 0(0,2)], bile duct inflammation [(2(1,3) vs. 1(1,2)] and bile duct reaction score [(2(1,3) vs. 1(1,2)] were higher in the positive group than those of the negative group ( P<0.05), and the maturity of the tertiary lymphoid structure was higher ( P=0.011). Kaplan-Meier analysis showed that the 5-year disease-free survival rate was significantly lower in patients with positive anti-gp210 antibodies than that of the negative group (55.8% vs. 79.7%, P=0.006) at a median follow-up of 3(2,6) years. Multivariate Cox regression analysis showed that γ-glutamyl transferase [ HR=1.002 (95% CI: 1.000～1.003)] and platelet count [ HR=0.993 (95% CI: 0.988～0.999)] were the independent influencing factors for disease progression in patients with anti-gp210 antibody-positive PBC ( P=0.002, 0.017). Conclusion:Patients with anti-gp210 antibody-positive PBC have more severe clinical pathological manifestations and a higher risk of disease progression. Higher levels of γ-glutamyl transferase and lower platelet counts during the first visit are independent risk factors for disease progression in patients with anti-gp210 antibody-positive PBC, which can be used as dynamic monitoring indicators for this population, suggesting the need for early intensive intervention.

Microalgae can achieve sustainable CO2 fixation and biomass conversion,making them a green path for carbon capture and conversion.Monitoring extracellular carbonic anhydrase(CA)activity in microalgae is crucial for regulating carbon conversion efficiency.In this study,double-stranded DNA was designed as a capture probe to bind H+,which was produced by CA-catalyzed CO2 hydration.This interaction induced conformational changes in the DNA probe,enhancing fluorescence signals and thereby establishing a recognition and signal transduction mechanism for CA catalytic product.This approach enabled a novel method for measuring CA activity.The response of probe to H+was investigated using ultraviolet visible(UV-Vis)spectroscopy,circular dichroism sepctroscopy,and fluorescence spectroscopy.The experimental results indicated that the fluorescence intensity of the probe increased progressively with rising H+concentration.Using this probe,CA activity detection could be completed within 29 min,with a detection range of 0.35-17500 U/mL and a detection limit of 0.15 U/mL.Compared to traditional methods,this approach offered a lower detection limit and was suitable for analyzing and detecting extracellular CA activity in actual algal samples.

Objective:To investigate the influening factors for postoperative paroxysmal sympathetic hyperactivity (PSH) and prolonged disorders of consciousness (pDoC) in patients with severe traumatic brain injury (sTBI).Methods:A retrospective cross-sectional study was performed; 204 patients with sTBI accepted surgery in Department of Neurosurgery, Second Affiliated Hospital of Fuyang Normal University from January 2018 to April 2024 were enrolled. These patients were divided into PSH group and non-PSH group based on postoperative PSH occurrence. These patients were also divided into pDoC group and non-pDoC group depending on whether duration of postoperative pDoC exceeded 28 days. Differences in clinical data between the PSH group and non-PSH group, as well as between the pDoC group and non-pDoC group, were compared respectively. Multivariate Logistic regression analysis was used to determine the independent influencing factors for PSH or pDoC. Receiver operating characteristic curve was used to investigate the predictive value of these influencing factors in PSH or pDoC in patients with sTBI.Results:(1) Of these 204 patients with sTBI, 28 patients (13.7 %) experienced PSH and 176 patients (86.3 %) were without PSH; compared with the non-PSH group, the PSH group had younger age, lower Glasgow Coma Scale (GCS) score on admission, higher proportions of patients with brain herniation, basilar skull fracture and traumatic intraventricular hemorrhage, higher proportion of patients accepted decompressive craniectomy, higher blood glucose level and neutrophil-to-lymphocyte ratio (NLR), and higher proportion of patients with postoperative hydrocephalus, with significant differences ( P<0.05). Of these 204 patients with sTBI, 77 patients (37.7 %) suffered from pDoC, and 127 (62.3 %) were without pDoC; compared with the non-pDoC group, the pDoC group had older age, lower GCS score on admission, higher proportions of patients with brain herniation, basilar skull fracture and traumatic intraventricular hemorrhage, higher proportion of patients accepted decompressive craniectomy, and higher proportions of patients with postoperative hydrocephalus or postoperative PSH, with significant differences ( P<0.05). (2) Multivariate Logistic regression analysis showed that age, skull base fracture, traumatic intraventricular hemorrhage, blood glucose level, NLR, and postoperative hydrocephalus were independent influencing factors for PSH ( P<0.05); PSH, age, GCS score on admission, and postoperative hydrocephalus were independent influencing factors for pDoC ( P<0.05). (3) Areas under the curve (AUC) of age, skull base fracture, traumatic intraventricular hemorrhage, blood glucose level, NLR and postoperative hydrocephalus in predicting PSH were 0.750, 0.718, 0.760, 0.756, 0.790 and 0.679, respectively; AUC of age, GCS score on admission, postoperative hydrocephalus, postoperative PSH and their combinations in predicting pDoC were 0.598, 0.833, 0.691, 0.630 and 0.925, respectively. Conclusion:The sTBI patients with younger age, skull base fracture, traumatic intraventricular hemorrhage, high blood glucose level and NLR, or hydrocephalus are prone to have postoperative PSH; the sTBI patients with older age, low GCS score on admission, postoperative hydrocephalus or postoperative PSH are prone to have postoperative pDoC.

Objective:To investigate the influening factors for postoperative paroxysmal sympathetic hyperactivity (PSH) and prolonged disorders of consciousness (pDoC) in patients with severe traumatic brain injury (sTBI).Methods:A retrospective cross-sectional study was performed; 204 patients with sTBI accepted surgery in Department of Neurosurgery, Second Affiliated Hospital of Fuyang Normal University from January 2018 to April 2024 were enrolled. These patients were divided into PSH group and non-PSH group based on postoperative PSH occurrence. These patients were also divided into pDoC group and non-pDoC group depending on whether duration of postoperative pDoC exceeded 28 days. Differences in clinical data between the PSH group and non-PSH group, as well as between the pDoC group and non-pDoC group, were compared respectively. Multivariate Logistic regression analysis was used to determine the independent influencing factors for PSH or pDoC. Receiver operating characteristic curve was used to investigate the predictive value of these influencing factors in PSH or pDoC in patients with sTBI.Results:(1) Of these 204 patients with sTBI, 28 patients (13.7 %) experienced PSH and 176 patients (86.3 %) were without PSH; compared with the non-PSH group, the PSH group had younger age, lower Glasgow Coma Scale (GCS) score on admission, higher proportions of patients with brain herniation, basilar skull fracture and traumatic intraventricular hemorrhage, higher proportion of patients accepted decompressive craniectomy, higher blood glucose level and neutrophil-to-lymphocyte ratio (NLR), and higher proportion of patients with postoperative hydrocephalus, with significant differences ( P<0.05). Of these 204 patients with sTBI, 77 patients (37.7 %) suffered from pDoC, and 127 (62.3 %) were without pDoC; compared with the non-pDoC group, the pDoC group had older age, lower GCS score on admission, higher proportions of patients with brain herniation, basilar skull fracture and traumatic intraventricular hemorrhage, higher proportion of patients accepted decompressive craniectomy, and higher proportions of patients with postoperative hydrocephalus or postoperative PSH, with significant differences ( P<0.05). (2) Multivariate Logistic regression analysis showed that age, skull base fracture, traumatic intraventricular hemorrhage, blood glucose level, NLR, and postoperative hydrocephalus were independent influencing factors for PSH ( P<0.05); PSH, age, GCS score on admission, and postoperative hydrocephalus were independent influencing factors for pDoC ( P<0.05). (3) Areas under the curve (AUC) of age, skull base fracture, traumatic intraventricular hemorrhage, blood glucose level, NLR and postoperative hydrocephalus in predicting PSH were 0.750, 0.718, 0.760, 0.756, 0.790 and 0.679, respectively; AUC of age, GCS score on admission, postoperative hydrocephalus, postoperative PSH and their combinations in predicting pDoC were 0.598, 0.833, 0.691, 0.630 and 0.925, respectively. Conclusion:The sTBI patients with younger age, skull base fracture, traumatic intraventricular hemorrhage, high blood glucose level and NLR, or hydrocephalus are prone to have postoperative PSH; the sTBI patients with older age, low GCS score on admission, postoperative hydrocephalus or postoperative PSH are prone to have postoperative pDoC.

Objective:To investigate the clinical efficacy of botulinum toxin type A（BTX-A）bladder injection in the treatment of neurogenic detrusor overactivity（NDO）with autonomic dysreflexia（AD）.Methods:The patients with spinal cord injury at or above T6，who were treated at Guangdong Provincial Work Injury Rehabilitation Hospital from January 2018 to December 2022，were included in this study prospectively. Inclusion criteria：①chronic spinal cord injury patients over 18 years old（with no progression of neurological symptoms within 3 months）；② presence of NDO and AD；③ inadequate response or intolerance to oral antimuscarinic agent（M-receptor antagonists or β 3-receptor agonists）④ perform clean intermittent catheterization to empty the bladder. Exclusion criteria：① primary disease in the acute or progressive phase；② previous surgeries that would affect lower urinary tract function，such as transurethral sphincterotomy，bladder neck resection，prostatectomy，or bladder surgery；③ allergy to BTX-A or its adjuvants，or those with allergic predisposition ④ patients who were pregnant，breastfeeding，or planning for pregnancy in the near future；⑤ patients did not accept or were unable to perform intermittent catheterization. Before treatment，all patients were required to maintain 3-5 day urine diary，along with urodynamic studies（UDS），incontinence specific quality of life instrument（I-QOL）and AD symptom severity assessment，and blood pressure monitored. Key UDS parameters recorded included maximum bladder capacity，maximum detrusor pressure during filling phase，changes in maximum systolic blood pressure（SBP）relative to baseline（ΔSBP）during UDS examination，and the frequency of 24-hour blood pressure exceeding baseline by 20 mmHg. After general anesthesia or epidural anesthesia，BTX-A（200 U）was injected into the bladder at 30 points（including the triangle）under the cystoscope using a special injection needle，6.7 U per injection，and then the catheter was kept for 3-5 days after treatment. Three months later，relevant indicators were collected and compared with pre-treatment data. Results:A total of 43 patients were included in this study，including 34 males and 9 females. The age was（39.23±13.17）years old and the disease course was（2.69±3.27）years old. There were 33 cervical and 10 thoracic cases. The American Spinal Injury Association Injury Scale score distribution was as follows：26（60%）A，4（9%）B，9（21%）C，and 4（9%）D. The presence of AD was confirmed in all patients during urodynamic examination（UDS），that was the systolic blood pressure（SBP）suddenly increased and exceeded 20 mmHg（1 mmHg = 0.133 kPa）. Before treatment，The AD symptoms severity score（consist of headache，sweating，goose bumps，anxiety and palpitation）were（14.53±2.51），Bladder-related AD frequency was 10.67 episodes/day. Baseline SBP was（103.51±9.64）mmHg，the maximum SBP was（150.40±22.75）mmHg，and the change in SBP（ΔSBP）from maximum to baseline SBP during UDS examination was（43.83±21.01）mmHg. The UDS indicated that the maximum detrusor pressure during storage phase was（54.95±24.68）cmH 2O，and the bladder capacity was（131.70±75.29）ml. Bladder diary showed the volume of catheterization each time from was（181.16±49.86）ml，and The I-QOL score was（44.07±8.60）. Three months after treatment，the AD symptoms severity score（consist of headache，sweating，goose bumps，anxiety and palpitation）were（11.37±2.39）. The frequency of bladder-related AD episodes was（7.51±2.37）episodes/day，showing statistically significant differences compared to pre-treatment（ P<0.05）.The SBP before UDS examination was（102.12±10.28）mmHg，with no statistically significant difference from baseline（ P = 0.518）. The maximum SBP in perfusion phase and the ΔSBP were（132.84±16.30）mmHg and（28.72 ± 14.02）mmHg，respectively，both demonstrating statistically significant differences（ P < 0.05）. The UDS examination revealed that the maximum detrusor pressure during the storage phase was（29.77±13.72）cmH 2O，showed a significant decrease，and the bladder capacity was（272.63±79.75）ml，which were both statistically different before and after surgery. Bladder diary showed the volume of catheterization each time was（326.74±63.71）ml；I-QOL score was（71.86±11.45），both were significant different after treatment（ P < 0.01）. Conclusion:BTX-A intravesical injection in the treatment of NDO can also alleviate the severity and frequency of bladder related AD.

Objective:To explore the clinical characteristics and identification of the independent risk factors for disease progression in patients with anti-gp210 antibody-positive primary biliary cholangitis (PBC).Methods:A retrospective cohort study was performed. A total of 323 cases with PBC diagnosed in Tianjin Medical University General Hospital from January 2013 to June 2023 (125 patients with anti-gp210 antibody-positive and 198 patients with anti-gp210 antibody-negative) were included. Baseline and follow-up data were collected. The independent sample t-test and Mann-Whitney U rank sum test were used for comparison between groups of continuous data. The χ2 test was used to compare the data between groups for the count data. The Pearson test was used for correlation analysis between continuous variables. The Kaplan-Meier method was used to analyze the disease progression-free survival rate. The Cox regression model was used to analyze the risk factors for disease progression. Results:The male proportion (11.2% vs. 5.1%, P=0.040) and IgM level [3.29(1.88, 4.80) g/L vs. 2.56(1.44, 3.87) g/L, P=0.019] were significantly higher in patients with PBC with positive anti-gp210 antibodies than those of the negative group. Histopathological analysis showed that the Scheuer score [1(0,3) vs. 0(0,2)], bile duct inflammation [(2(1,3) vs. 1(1,2)] and bile duct reaction score [(2(1,3) vs. 1(1,2)] were higher in the positive group than those of the negative group ( P<0.05), and the maturity of the tertiary lymphoid structure was higher ( P=0.011). Kaplan-Meier analysis showed that the 5-year disease-free survival rate was significantly lower in patients with positive anti-gp210 antibodies than that of the negative group (55.8% vs. 79.7%, P=0.006) at a median follow-up of 3(2,6) years. Multivariate Cox regression analysis showed that γ-glutamyl transferase [ HR=1.002 (95% CI: 1.000～1.003)] and platelet count [ HR=0.993 (95% CI: 0.988～0.999)] were the independent influencing factors for disease progression in patients with anti-gp210 antibody-positive PBC ( P=0.002, 0.017). Conclusion:Patients with anti-gp210 antibody-positive PBC have more severe clinical pathological manifestations and a higher risk of disease progression. Higher levels of γ-glutamyl transferase and lower platelet counts during the first visit are independent risk factors for disease progression in patients with anti-gp210 antibody-positive PBC, which can be used as dynamic monitoring indicators for this population, suggesting the need for early intensive intervention.

Objective:To investigate and summarize the imaging and pathological features of non-acute occlusion following flow diverter (FD) implantation in animal models.Methods:Four experimental pigs (experimental group) that experienced non-acute occlusion (occlusion time exceeding 24 hours) within the FD stent implanted in the common carotid artery, and 19 pigs (control group) that did not experience stent occlusion during the same period were involved. Using an interventional approach under digital subtraction angiography (DSA), the 4 occluded FD lumens were mechanically opened. Optical coherence tomography (OCT), intravascular ultrasound (IVUS) and histopathological examinations were performed to evaluate the intraluminal composition and characteristics of the occlusive tissues. These findings were compared with non-occluded FD stents to summarize the imaging and pathological changes within the occluded FD lumen.Results:The occlusion times of the FD stents in the 4 experimental pigs were 16 weeks, 20 weeks, 20 weeks, and 24 weeks postoperatively. All occluded stents were successfully recanalized under DSA, with a technical success rate of 4/4. Among the 19 non-occluded FD stents, OCT and IVUS revealed uniform (16 stents) or non-uniform (3 stents) neointimal coverage of the stent struts, presenting as homogeneous high/slightly high signal intensity or medium echogenicity. Histopathological examination indicated that the neointima was primarily composed of smooth muscle cells and a small amount of fibrous connective tissues. In contrast, the 4 occluded FD stents demonstrated excessive neointimal proliferation and plaque formation, leading to luminal loss, as shown by OCT and IVUS. The occlusion tissues predominantly presented as homogeneous high signal intensity with weak attenuation (fibrous plaques) on OCT, with some regions showing blurred low signal intensity and strong attenuation (lipid plaques). IVUS presented homogeneous echogenicity (fibrous plaques) and hypoechogenic zones (lipid plaques). Histopathological examination showed that the occlusion tissues mainly consisted of smooth muscle cells, fibrous connective tissues, and lipids, accompanied by numerous foam cells and a minor presence of inflammatory cells.Conclusions:Histopathological examinations confirm that non-acute occlusion of FD is mainly caused by excessive hyperplasia of intima along with the formation of fibrous plaques and lipid plaques. OCT and IVUS have typical finding in imaging that can assist in determining the cause of stent occlusion as well as the lesion's nature, thereby providing crucial guidance for subsequent clinical treatment and drug selection.

Objective:This article introduces a novel technique for totally laparoscopic, right thoracic approach, esophagojejunostomy for digestive tract reconstruction.Methods:A retrospective analysis was conducted on the clinical data of patients with adenocarcinoma of the esophagogastric junction who successfully underwent totally laparoscopic esophagojejunostomy via the right thoracic approach at Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, between February 2022 and March 2022.The surgical procedure was performed as follows:(1)Following total laparoscopic resection of the gastric tumor and lymph node dissection, the specimen was transected distal to the tumor margin. The specimen was then placed into a retrieval bag and extracted through the umbilical observation port.(2)Dissection was continued through the esophageal hiatus to mobilize the esophagus. The tumor-bearing tissue, along with the esophagus, was delivered into the thoracic cavity via the esophageal hiatus.(3)The jejunum was transected 20 cm distal to the ligament of Treitz. The distal Jejunum was mobilized for 15-20 cm and subsequently delivered into the thoracic cavity through the esophageal hiatus.(4)A Roux-en-Y jejunojejunostomy was constructed 45-50 cm distal to the cut end of the distal jejunal limb; the mesenteric defect was closed, and the duodenal stump was reinforced.(5)The patient was repositioned into the left lateral decubitus position. Port placement was established as follows: the observation port at the 7th intercostal space (ICS) in the right midaxillary line, the main operating port at the 4th ICS in the anterior axillary line, and the assistant operating port at the 9th ICS in the scapular line.(6)The main operating port incision was enlarged. Using a purse-string instrument, the esophagus was clamped and transected at least 5 cm proximal to the upper tumor margin, and the specimen was removed. (7)The distal jejunum was delivered into the thoracic cavity via the esophageal hiatus. Under total laparoscopic visualization, esophagojejunostomy was completed.Results:Both patients who underwent totally laparoscopic esophagojejunostomy via the right thoracic cavity successfully completed the procedure without conversion to laparotomy, unplanned reoperation, or any intraoperative/postoperative complications. The patients recovered well postoperatively, with no evidence of abdominal or thoracic hemorrhage. Postoperative computed tomography (CT) scans of the chest and abdomen confirmed the absence of anastomotic leakage or other related complications.Conclusions:The esophagojejunostomy was performed totally laparoscopically via the right thoracic cavity. This approach overcomes the drawback of significant trauma associated with open surgery while ensuring safe esophageal resection margins and thorough lymph node dissection. This technique offers advantages including minimal invasiveness, accelerated postoperative recovery, and a reduced incidence of reflux esophagitis. To our knowledge, no similar method of digestive tract reconstruction has been reported in the literature. Its novelty and clinical potential may offer new therapeutic options for patients with Siewert type II adenocarcinoma of the esophagogastric junction (AEG).