The engineering application of microbially induced carbonate precipitation(MICP)is limited by pH-dependent conformational dynamics of urease.Focusing on the α-subunit urease from Sporosarcina pasteurii,this study integrated conductivity experiments and constant-pH molecular dynamics simulations to analyze active site conformational dynamics and catalytic function across pH 3-11.Results showed that under neutral conditions(pH 7-8),key histidine residues(HIS139/HIS249)exhibited minimal dis-placement(＜0.5 ?),the longest hydrogen bond lifetime(＞8 ps),highest conformational stability(root mean square deviation,RMSD:0.15-0.18 nm),and optimal catalytic activity(conductivity change rate:0.03 mS/cm·min-1,CaCO3 precipitation:3.84 g).Extreme pH(pH 3/11)induced structural collapse(displacement up to 1.8 ?)and complete activity loss.Simulations revealed that neutral pH sta-bilizes a protonation-dependent cooperative allosteric network by maintaining active site cavity volume(～120 ?3)and moderate conformational coherence(correlation coefficient～0.8).This work deciphers the molecular mechanism of pH-regulated urease dynamics through protonation states,providing theoreti-cal support for MICP applications in acidic mine tailing remediation and alkaline soil stabilization.

Laparoscopic pancreaticoduodenectomy(LPD) poses a high risk of intraoperative bleeding due to the complex anatomy and rich blood supply in the pancreatic head region. This paper innovatively proposes a blood flow control technique system for LPD, adopting a strategy of “priority devascularization and pre-blocking”.By first addressing the peripheral collateral blood supply and the gastroduodenal artery, and then performing dual-system pre-blocking, the dorsal pancreatic artery and the inferior pancreaticoduodenal artery are treated in situ through a combined middle and left posterior approach. This progressive blood flow control method enhances surgical safety and oncological radicality, offering a new paradigm for the development of minimally invasive pancreatic surgery.

The engineering application of microbially induced carbonate precipitation(MICP)is limited by pH-dependent conformational dynamics of urease.Focusing on the α-subunit urease from Sporosarcina pasteurii,this study integrated conductivity experiments and constant-pH molecular dynamics simulations to analyze active site conformational dynamics and catalytic function across pH 3-11.Results showed that under neutral conditions(pH 7-8),key histidine residues(HIS139/HIS249)exhibited minimal dis-placement(＜0.5 ?),the longest hydrogen bond lifetime(＞8 ps),highest conformational stability(root mean square deviation,RMSD:0.15-0.18 nm),and optimal catalytic activity(conductivity change rate:0.03 mS/cm·min-1,CaCO3 precipitation:3.84 g).Extreme pH(pH 3/11)induced structural collapse(displacement up to 1.8 ?)and complete activity loss.Simulations revealed that neutral pH sta-bilizes a protonation-dependent cooperative allosteric network by maintaining active site cavity volume(～120 ?3)and moderate conformational coherence(correlation coefficient～0.8).This work deciphers the molecular mechanism of pH-regulated urease dynamics through protonation states,providing theoreti-cal support for MICP applications in acidic mine tailing remediation and alkaline soil stabilization.

Laparoscopic pancreaticoduodenectomy(LPD) poses a high risk of intraoperative bleeding due to the complex anatomy and rich blood supply in the pancreatic head region. This paper innovatively proposes a blood flow control technique system for LPD, adopting a strategy of “priority devascularization and pre-blocking”.By first addressing the peripheral collateral blood supply and the gastroduodenal artery, and then performing dual-system pre-blocking, the dorsal pancreatic artery and the inferior pancreaticoduodenal artery are treated in situ through a combined middle and left posterior approach. This progressive blood flow control method enhances surgical safety and oncological radicality, offering a new paradigm for the development of minimally invasive pancreatic surgery.

Objective To investigate the risk factors for bronchopulmonary dysplasia(BPD)in twin preterm infants with a gestational age of<34 weeks,and to provide a basis for early identification of BPD in twin preterm infants in clinical practice.Methods A retrospective analysis was performed for the twin preterm infants with a gestational age of<34 weeks who were admitted to 22 hospitals nationwide from January 2018 to December 2020.According to their conditions,they were divided into group A(both twins had BPD),group B(only one twin had BPD),and group C(neither twin had BPD).The risk factors for BPD in twin preterm infants were analyzed.Further analysis was conducted on group B to investigate the postnatal risk factors for BPD within twins.Results A total of 904 pairs of twins with a gestational age of<34 weeks were included in this study.The multivariate logistic regression analysis showed that compared with group C,birth weight discordance of>25%between the twins was an independent risk factor for BPD in one of the twins(OR=3.370,95%CI:1.500-7.568,P<0.05),and high gestational age at birth was a protective factor against BPD(P<0.05).The conditional logistic regression analysis of group B showed that small-for-gestational-age(SGA)birth was an independent risk factor for BPD in individual twins(OR=5.017,95%CI:1.040-24.190,P<0.05).Conclusions The development of BPD in twin preterm infants is associated with gestational age,birth weight discordance between the twins,and SGA birth.

Objective To construct microscale rectangular hydrogel grooves and to investigate the morphology and alignment of human umbilical vein endothelial cells(HUVECs)under spatial constraints.Vascular endothelial cell morphology and alignment are important factors in vascular development and the maintenance of homeostasis.Methods A 4-arm polyethylene glycol-acrylate(PEG-acrylate)hydrogel was used to fabricate rectangular microgrooves of the widths of 60 μm,100 μm,and 140 μm.The sizes and the fibronectin(FN)adhesion of these hydrogel microgrooves were measured.HUVECs were seeded onto the FN-coated microgrooves,while the flat surface without micropatterns was used as the control.After 48 hours of incubation,the morphology and orientation of the cells were examined.The cytoskeleton was labelled with phalloidine and the orientation of the cytoskeleton in the hydrogel microgrooves was observed by laser confocal microscopy.Results The hydrogel microgrooves constructed exhibited uniform and well-defined morphology,a complete structure,and clear edges,with the width deviation being less than 3.5%.The depth differences between the hydrogel microgrooves of different widths were small and the FN adhesion is uniform,providing a micro-patterned growth interface for cells.In the control group,the cells were arranged haphazardly in random orientations and the cell orientation angle was(46.9±1.8)°.In contrast,the cell orientation angle in the hydrogel microgrooves was significantly reduced(P<0.001).However,the cell orientation angles increased with the increase in hydrogel microgroove width.For the 60 μm,100 μm,and 140 μm hydrogel microgrooves,the cell orientation angles were(16.4±2.8)°,(24.5±3.2)°,and(30.3±3.5)°,respectively.Compared to that of the control group(35.7%),the number of cells with orientation angles<30° increased significantly in the hydrogel microgrooves of different widths(P<0.001).However,as the width of the hydrogel microgrooves increased,the number of cells with orientation angles<30° gradually decreased(79.9%,62.3%,54.7%,respectively),while the number of cells with orientation angles between 60°-90° increased(P<0.001).The cell bodies in the microgrooves were smaller and more rounded in shape.The cells were aligned along the direction of the microgrooves and corresponding changes occurred in the arrangement of the cell cytoskeleton.In the control group,cytoskeletal filaments were aligned in random directions,presenting an orientation angle of(45.5±3.7)°.Cytoskeletal filaments were distributed evenly within various orientation angles.However,in the 60 μm,100 μm,and 140 μm hydrogel microgrooves,the orientation angles of the cytoskeletal filaments were significantly decreased,measuring(14.4±3.1)°,(24.7±3.5)°,and(31.9±3.3)°,respectively.The number of cytoskeletal filaments with orientation angles<30° significantly increased in hydrogel microgrooves of different widths(P<0.001).However,as the width of the hydrogel microgrooves increased,the number of cytoskeletal filaments with orientation angles<30° gradually decreased,while the number of cytoskeletal filaments with orientation angles between 60°-90° gradually increased(P<0.001).Conclusion Hydrogel microgrooves can regulate the morphology and orientation of HUVECs and mimic to a certain extent the in vivo microenvironment of vascular endothelial cells,providing an experimental model that bears better resemblance to human physiology for the study of the unique physiological functions of vascular endothelial cells.Nonetheless,the molecular mechanism of spatial constraints on the morphology and the assembly of vascular endothelial cell needs to be further investigated.

Objective:To investigate the clinical effect of proper management of inferior pancreaticoduodenal artery (IPDA) in laparoscopic pancreaticoduodenectomy (LPD).Methods:This is a retrospective case series study. The clinical and pathological data of 70 patients who received LPD due to pancreatic head tumors, periampullary tumors, or distal common bile duct tumors in the Pancreatic Center of the Second Clinical College of Guangzhou University of Chinese Medicine from January to December 2022 were retrospectively collected. There were 47 males(67.1%) and 23 females(32.9%),aged (59.9±12.8)years(range:13 to 87 years).The procedure of IPDA exposure was as follows:a middle approach was utilized to expose the right half of superior mesenteric artery(SMA) and its right branches between the SMA and superior mesenteric vein(SMV) in superior colonic region. In the subcolonic region,SMA trunk exposure via dissection along the jejunal artery from feet to head and identification the association between IPDA and jejunal artery were prior to IPDA root ligation and dissection. The safety and efficacy of intraoperative IPDA handling were assessed based on surgical videos. Follow-up was carried out in outpatient clinic or by telephone, and outpatient follow-up was conducted once every 1 to 3 months after surgery.Results:The percentage of total LPD was 98.6%(69/70),with all patients achieving R0 resection. Nine cases(12.9%) were involved in combined vascular resection and reconstruction,with 1 case (1.4%) requiring additional upper abdominal incision for vascular and gastrointestinal reconstruction,while the remaining eight cases (11.4%) were completed laparoscopically. The operative time was (432.7±115.4)minutes(range:282 to 727 minutes), and the blood loss was (140.0±125.7)ml(range:20 to 800 ml). Only two patients(2.9%) received fresh frozen plasma transfusion,with an average volume of 650 ml. Reliable ligation and safe handling of the IPDA were achieved in 91.4%(64/70) of cases, with 8.6%(6/70) suffering from IPDA injury-related bleeding. No one was converted to opened surgery. Pathologically,the mean tumor size was (3.3±1.6)cm (range:1 to 7 cm),and the mean number of harvested lymph nodes was 17.0±7.3(range:0 to 46). Lymph node metastasis was observed in 13 cases (18.6%). Five cases (13.2%) developed grade B pancreatic fistula,while no grade C pancreatic fistula occurred. Other complications included bile leakage in one case(1.4%),delayed gastric emptying in two cases(2.9%), lymphatic leakage in 2 cases(2.9%),intra-abdominal infection in 9 cases(12.9%),and fat liquefaction of surgical incision in 1 case(1.4%). Two cases(2.9%) experienced postoperative intra-abdominal bleeding,one due to mesangial bleeding of lesser curvature of the stomach and the other due to oozing from the hepatic arterial sheath. These bleeding events were not concerned with IPDA. The average length of postoperative hospital stay was (15.2±4.6)days(range:9 to 28 days).Conclusion:Proper intraoperative management of IPDA in LPD might reduce IPDA-related bleeding during and after surgery and improve the safety of LPD.

Ankylosing spondylitis (AS) combined with lower cervical fracture is often categorized into unstable fracture, with a high incidence of neurological injury and a high rate of disability and morbidity. As factors such as shoulder occlusion may affect the accuracy of X-ray imaging diagnosis, it is often easily misdiagnosed at the primary diagnosis. Non-operative treatment has complications such as bone nonunion and the possibility of secondary neurological damage, while the timing, access and choice of surgical treatment are still controversial. Currently, there are no clinical practice guidelines for the treatment of AS combined with lower cervical fracture with or without dislocation. To this end, the Spinal Trauma Group of Orthopedics Branch of Chinese Medical Doctor Association organized experts to formulate Clinical guidelines for the treatment of ankylosing spondylitis combined with lower cervical fracture in adults ( version 2024) in accordance with the principles of evidence-based medicine, scientificity and practicality, in which 11 recommendations were put forward in terms of the diagnosis, imaging evaluation, typing and treatment, etc, to provide guidance for the diagnosis and treatment of AS combined with lower cervical fracture.

Objective:To investigate the clinical effect of proper management of inferior pancreaticoduodenal artery (IPDA) in laparoscopic pancreaticoduodenectomy (LPD).Methods:This is a retrospective case series study. The clinical and pathological data of 70 patients who received LPD due to pancreatic head tumors, periampullary tumors, or distal common bile duct tumors in the Pancreatic Center of the Second Clinical College of Guangzhou University of Chinese Medicine from January to December 2022 were retrospectively collected. There were 47 males(67.1%) and 23 females(32.9%),aged (59.9±12.8)years(range:13 to 87 years).The procedure of IPDA exposure was as follows:a middle approach was utilized to expose the right half of superior mesenteric artery(SMA) and its right branches between the SMA and superior mesenteric vein(SMV) in superior colonic region. In the subcolonic region,SMA trunk exposure via dissection along the jejunal artery from feet to head and identification the association between IPDA and jejunal artery were prior to IPDA root ligation and dissection. The safety and efficacy of intraoperative IPDA handling were assessed based on surgical videos. Follow-up was carried out in outpatient clinic or by telephone, and outpatient follow-up was conducted once every 1 to 3 months after surgery.Results:The percentage of total LPD was 98.6%(69/70),with all patients achieving R0 resection. Nine cases(12.9%) were involved in combined vascular resection and reconstruction,with 1 case (1.4%) requiring additional upper abdominal incision for vascular and gastrointestinal reconstruction,while the remaining eight cases (11.4%) were completed laparoscopically. The operative time was (432.7±115.4)minutes(range:282 to 727 minutes), and the blood loss was (140.0±125.7)ml(range:20 to 800 ml). Only two patients(2.9%) received fresh frozen plasma transfusion,with an average volume of 650 ml. Reliable ligation and safe handling of the IPDA were achieved in 91.4%(64/70) of cases, with 8.6%(6/70) suffering from IPDA injury-related bleeding. No one was converted to opened surgery. Pathologically,the mean tumor size was (3.3±1.6)cm (range:1 to 7 cm),and the mean number of harvested lymph nodes was 17.0±7.3(range:0 to 46). Lymph node metastasis was observed in 13 cases (18.6%). Five cases (13.2%) developed grade B pancreatic fistula,while no grade C pancreatic fistula occurred. Other complications included bile leakage in one case(1.4%),delayed gastric emptying in two cases(2.9%), lymphatic leakage in 2 cases(2.9%),intra-abdominal infection in 9 cases(12.9%),and fat liquefaction of surgical incision in 1 case(1.4%). Two cases(2.9%) experienced postoperative intra-abdominal bleeding,one due to mesangial bleeding of lesser curvature of the stomach and the other due to oozing from the hepatic arterial sheath. These bleeding events were not concerned with IPDA. The average length of postoperative hospital stay was (15.2±4.6)days(range:9 to 28 days).Conclusion:Proper intraoperative management of IPDA in LPD might reduce IPDA-related bleeding during and after surgery and improve the safety of LPD.

Ankylosing spondylitis (AS) combined with spinal fractures with thoracic and lumbar fracture as the most common type shows characteristics of unstable fracture, high incidence of nerve injury, high mortality and high disability rate. The diagnosis may be missed because it is mostly caused by low-energy injury, when spinal rigidity and osteoporosis have a great impact on the accuracy of imaging examination. At the same time, the treatment choices are controversial, with no relevant specifications. Non-operative treatments can easily lead to bone nonunion, pseudoarthrosis and delayed nerve injury, while surgeries may be failed due to internal fixation failure. At present, there are no evidence-based guidelines for the diagnosis and treatment of AS combined with thoracic and lumbar fracture. In this context, the Spinal Trauma Academic Group of Orthopedics Branch of Chinese Medical Doctor Association organized experts to formulate the Clinical guideline for the diagnosis and treatment of adult ankylosing spondylitis combined with thoracolumbar fracture ( version 2023) by following the principles of evidence-based medicine and systematically review related literatures. Ten recommendations on the diagnosis, imaging evaluation, classification and treatment of AS combined with thoracic and lumbar fracture were put forward, aiming to standardize the clinical diagnosis and treatment of such disorder.