1.A modified procedure for replantation of severed digit-tips in Tamai zones I - II and the clinical effects
Yangyang LIU ; Min WU ; Jun ZHU ; Xubin GAO ; Kuankuan ZHANG ; Zhongbing HAN ; Haizhou NIU
Chinese Journal of Microsurgery 2024;47(1):78-83
Objective:To explore the clinical effect of a modified surgical procedure for replantation of severed digit-tips in Tamai zones I-II.Methods:From November 2019 to October 2022, the Department of Hand and Foot Microsurgery of the First Affiliated Hospital of Bengbu Medical College employed a modified procedure (to abandon the anatomically labelling of blood vessels and nerves after naked-eye debridement and fracture fixation, then perform the microscopic dissections and anastomoses of blood vessels and nerves, and the anastomosis of dorsal veins though an auxiliary small incision by the lateral nail fold of the severed digit-tip) to replant severed digit-tips in Tamai zones I-II of 26 patients (29 digits). The patients were 20 males (23 digits) and 6 females (6 digits), aged 3-66 years old, with mean age at 28 years old. Nineteen digit-tips were severed in Tamai zone I and 10 in Tamai zone II. The severed digit-tips were 7 of thumbs, 9 of index fingers, 5 of middle fingers, 5 of ring fingers and 3 of little fingers. Causes of injury were 12 of cut, 8 of crush and 6 of avulsion. Postoperative management included infection prevention, antispasmodic for 3 days and keeping in bed for 5 days. The time of surgery was recorded on all patients. Postoperative follow-ups were conducted at outpatient clinics for 6 to 12 months to observe the survival of digit-tips and the appearance, recovery of sensation and motor functions, strength of digits and patient satisfaction.Results:(1)The surgical time was about 1.0 hour for replantation of a severed digit-tip in Tamai zone I, while it took about 1.5 hours for those in Tamai zone II. (2)Survival rate and appearance: all 29 replanted digit-tips survived, except 2 in Tamai zone I which encountered venous occlusion and survived after small incision for bloodletting. Twenty-two digit-tips gained pulp fat pads with full digit pulps. Four avulsed digit-tips had mild atrophy of pulp. The 15 digit-tips severed in Tamai zone I were about 2 mm shorter than the healthy sides, but without deformity. One digit-tip had poor nail appearance due to preoperative fungal infection of nail bed. (3)Sensory recovery: with the British Medical Research Council (BMRC), 23 digit-tips recovered to S 3+, and 2 digit-tips of avulsion and 1 digit-tip of crush recovered to S 3. TPD of the replanted digit-tips were: 4-7 mm in those of cut injury; 6-8 mm in those of crush and 9-11 mm in those of avulsion. (4)Motion and digit strength: results of functional assessment according to the total active mobility standard promoted by China's Society for Surgery of the Hand were: 21 cases of excellent and 5 of good, without pain in digit pulp when pinching and griping. The mobility of the digits with replanted digit-tips of both Tamai zones I and II were close to that of the healthy sides. The motions of the digits with replanted digit-tips in Tamai zone I were close to the healthy sides and the 5 of those in Tamai zone II had 0° in extension and 2°-3° in flexion, due to the severed plane at distal interphalangeal joint. (5)Patient satisfaction: 25 patients were satisfied, however 1 patient was dissatisfied to the poor function of the distal interphalangeal joint due to the severed thumb-tip in Tamai zone II. Conclusion:Modified replantation procedure for severed digit-tip in Tamai zones I-II has significant achievement in cutting down the surgical time through a modified procedure of debridement and fracture fixation (tendon suture) by naked-eyes operation first, followed by dissections and anastomoses of the blood vessels and nerves under the surgical microscope. The auxiliary small incision by the lateral nail fold of digit-tip in Tamai zone I facilitates an exposure of a constant, healthy lateral nail fold vein. It enables the anastomosis with a high-quality vein, hence improves the success rate of replantation. The appearance and function of the replanted digit-tip are found better in the severed digit-tips of cut injury than those with injuries of avulsion and crush.
2.Clinical effects of free superficial circumflex iliac artery superficial branch perforator flap combined with full-thickness skin graft far from the flap donor site in repairing the large wounds in extremities
Yangyang LIU ; Min WU ; Jun ZHU ; Kuankuan ZHANG ; Haizhou NIU ; Xubin GAO ; Zhongbing HAN ; Fendou LIU
Chinese Journal of Burns 2024;40(1):72-77
Objective:To investigate the clinical effects of free superficial circumflex iliac artery (SCIA) superficial branch perforator flap combined with full-thickness skin graft far from the flap donor site in repairing the large wounds in extremities.Methods:The study was a retrospective observational study. From January 2020 to June 2022, 19 patients with large wounds in extremities who met the inclusion criteria were admitted to the First Affiliated Hospital of Bengbu Medical College, including 15 males and 4 females, aged 28-75 years. The debridement, fracture reduction and fixation, tendon, vessel, and nerve repair, and vacuum sealing drainage were performed in the first stage surgery. After debridement in the second stage surgery, the total wound area was 13.0 cm×8.0 cm-34.0 cm×15.0 cm. The tendon and bone exposed wound with area of 9.0 cm×6.0 cm-14.0 cm×7.0 cm was repaired with free SCIA superficial branch perforator flap with area of 10.0 cm×6.5 cm-15.0 cm×8.0 cm. The remaining granulation tissue wound with area of 5.0 cm×3.5 cm-13.0 cm×8.0 cm was repaired with full-thickness skin graft far from the flap donor site with area of 5.0 cm×3.5 cm-13.0 cm×8.0 cm. All the wounds in donor site were sutured. The operation time and amount of bleeding of patients during the surgery were recorded, the survival of flap and skin graft were observed after surgery. During follow-up, the flap and skin graft, scar in the donor site and its effect on donor site function were observed. At the last follow-up, the satisfaction of patients with the efficacy was evaluated by the efficacy satisfaction rating score.Results:The operation time of patients was 2.0-3.5 h. The amount of bleeding of patients during the surgery was 100-320 mL. One patient had ecchymosis and venous crisis in the edge of flap on the second day after surgery, and the flap survived after exploration. The flaps of the other patients survived smoothly. The skin grafts of patients all survived smoothly. Two patients had bloated flaps due to obesity in the later stage, and the expected results were achieved after flap thinning surgery 6 months after operation. During the follow-up of 6 to 24 months, the flaps had good elasticity and soft texture, and the skin grafts had no wear or ulceration; linear scars were left in all the donor sites but their functions were not affected. The patients were all satisfied with the efficacy.Conclusions:Free SCIA superficial perforator flap combined with full-thickness skin graft far from the donor site was used to repair the large wounds in extremities, which was safe, reliable, and less traumatic and short in operation time, and resulted in good postoperative appearance and function in the donor sites and recipient sites.
3.Molecular dynamics simulation of force-regulated interaction between glycoprotein Ib α and filamin.
Rencai TAO ; Xubin XIE ; Jianhua WU ; Ying FANG
Journal of Biomedical Engineering 2023;40(5):876-885
In resting platelets, the 17 th domain of filamin a (FLNa17) constitutively binds to the platelet membrane glycoprotein Ibα (GPIbα) at its cytoplasmic tail (GPIbα-CT) and inhibits the downstream signal activation, while the binding of ligand and blood shear force can activate platelets. To imitate the pull force transmitted from the extracellular ligand of GPIbα and the lateral tension from platelet cytoskeleton deformation, two pulling modes were applied on the GPIbα-CT/FLNa17 complex, and the molecular dynamics simulation method was used to explore the mechanical regulation on the affinity and mechanical stability of the complex. In this study, at first, nine pairs of key hydrogen bonds on the interface between GPIbα-CT and FLNa17 were identified, which was the basis for maintaining the complex structural stability. Secondly, it was found that these hydrogen bonding networks would be broken down and lead to the dissociation of FLNa17 from GPIbα-CT only under the axial pull force; but, under the lateral tension, the secondary structures at both terminals of FLNa17 would unfold to protect the interface of the GPIbα-CT/FLNa17 complex from mechanical damage. In the range of 0~40 pN, the increase of pull force promoted outward-rotation of the nitrogen atom of the 563 rd phenylalanine (PHE 563-N) at GPIbα-CT and the dissociation of the complex. This study for the first time revealed that the extracellular ligand-transmitted axial force could more effectively relieve the inhibition of FLNa17 on the downstream signal of GPIbα than pure mechanical tension at the atomic level, and would be useful for further understanding the platelet intracellular force-regulated signal pathway.
Filamins/metabolism*
;
Platelet Glycoprotein GPIb-IX Complex/metabolism*
;
Molecular Dynamics Simulation
;
Ligands
;
Protein Binding
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Blood Platelets/metabolism*
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von Willebrand Factor/metabolism*
4.Posterior vertebral column resection combined with polymethylmethacrylate-augmented pedicle screw instrumentation and shortening of spinal column for stage Ⅲ Kümmell's disease with very severe collapse of fractured vertebra
Xubin JI ; Feng LI ; Zhaowan XU ; Naiwang CHEN ; Dayong LIU ; Yang ZHANG ; Qinmin WU ; Wanping ZHU ; Xiaopeng LI ; Long LI
Chinese Journal of Orthopaedic Trauma 2023;25(7):601-609
Objective:To investigate the feasibility and clinical efficacy of posterior vertebral column resection (PVCR) combined with polymethylmethacrylate-augmented pedicle screw instrumentation and shortening of spinal column for stage Ⅲ Kümmell's disease with very severe collapse of fractured vertebra.Methods:From January 2017 to September 2021, 9 patients with stage Ⅲ Kümmell's disease with very severe collapse of fractured vertebra underwent PVCR combined with polymethylmethacrylate-augmented pedicle screw instrumentation and shortening of spinal column. Their medical records were retrospectively analyzed. There were 1 male and 8 females, aged (66.9±5.8) years. The injured vertebra was located at T 11 in 2 patients, at T 12 in 4, at L 1 in 2 and at L 2 in 1. X-ray, CT and MRI were performed before operation. The posterior intervertebral heights of adjacent vertebral bodies of the fractured vertebra in the median sagittal position were measured on CT or MRI to evaluate the shortening of the spinal column before PVCR. Recorded were intraoperative bleeding volume, operation time, complications, bone graft fusion, and American Spinal Injury Association (ASIA) grading at preoperation and the last follow-up. The visual analogue scale (VAS) pain scores, Oswestry disability index (ODI) scores, and kyphotic cobb angles at preoperation, 1 week and 3 months postoperation, and the last follow-up were compared to evaluate the clinical efficacy of PVCR. Results:All patients underwent surgery successfully, with tight closure of adjacent vertebrae after resection of the injured vertebra and bone grafting. Operation time was (240.6±23.2) min and intraoperative bleeding (505.6±95.0) mL. The 9 patients were followed up for (17.3±5.6) months. No worsening symptoms of nerve injury, cerebrospinal fluid leakage, or other serious complications were found after operation, nor such complications as loosening or breakage of internal fixation or adjacent vertebral fractures. Bone fusion was achieved at the bone graft sites in all patients by the last follow-up. The VAS and ODI scores and cobb angles at 1 week and 3 months postoperation and at the last follow-up were significantly decreased compared with preoperation ( P<0.05). There were no significant differences in VAS scores or cobb angles among postoperative 1 week and 3 months and the last follow-up ( P>0.05), but pairwise comparisons between different time points after operation showed significant differences in ODI, with postoperative 1 week > postoperative 3 months > the last follow-up ( P<0.05). The ASIA grading at the last follow-up was improved from preoperative grade C to grade D in 2 cases, from preoperative grade C to grade E in 1 case and from preoperative grade D to grade E in 5 cases. Conclusion:PVCR combined with polymethylmethacrylate-augmented pedicle screw instrumentation and shortening of spinal column is a feasible and effective surgical treatment for stage Ⅲ Kümmell's disease with very severe collapse of fractured vertebra, leading to good clinical efficacy.
5.Progress in the pathogenesis and treatment of non suicidal self injury in adolescents
HUAN Zongsu, HE Xubin, DU Na, WU Dongmei, YUE Yuchuan
Chinese Journal of School Health 2023;44(4):636-640
Abstract
Non suicide self injury is highly common in adolescents, which is seriously threatening their physical and mental health. It is an important predictor of future suicide, and has become a focus of global public health concern. At present, the research on adolescent non suicidal self injury is still in its infancy, and its formation process is complex. The pathogenesis is not completely clear, and the relevant treatment studies are relatively few. The paper expounds the pathogenesis and treatment of the nonsuicidal adolescent NSSI from the perspectives of genetics, neurobiology, neuroimage and social psychology, aiming to provide a theoretical basis for adolescent NSSI prevention and intervention.
6.Retrospective analysis of three different types of tissue flaps in reconstruction of tissue defects of orbital region
Xubin WU ; ·Maimaiti ABUDUKELIMUJIANG ; Zhitao YAO ; ·Saimaiti ADILIJIANG ; ·Tuerxun JULAITI ; Wei AN ; Tairan DING ; Simin ZHANG ; ·Tuerdi MAIMAITITUXUN
Chinese Journal of Plastic Surgery 2023;39(5):479-489
Objective:To investigate the clinical effect of three different tissue flaps in repairing patients with orbital region tissue loss after enlarged resection of malignant tumors in the orbital region, as well as the indication.Methods:Retrospective analysis of data of patients with malignant tumors in the orbital region treated in the Department of Oral and Maxillofacial Trauma and Orthognathic Surgery, the First Affiliated Hospital of Xinjiang Medical University (Affiliated Stomatological Hospital) between January 2017 and December 2021. All patients underwent extensive resection of periorbital malignant tumors and enucleation of orbital contents, depending on defects in periorbital soft/hard tissues and orbital contents, temporalis myofascial flap combined with full thickness skin grafts (TMF-FTSG group), modified pectoralis major myocutaneous flap (PMMF group), and free anterolateral thigh flap (ALTF group) were used to repair the tissue defect. The wound healing and complications of the donor and recipient areas were followed up after operation, and degree of mouth opening in the TMF-FTSG group was compared at 3 months after operation and before operation. The University of Washington quality of life scale (UW-QOL) score was compared among the three groups before and 1 year after operation (a total of 12 items, each item was assigned from 0 to 100 points, the higher the score, the better the recovery). Statistical software SPSS 26.0 was used to analyze the data. The measurement data were expressed as Mean±SD, and the paired t-test was used to compare the preoperative and postoperative data within the group, the difference was statistically significant at a P value less than 0.05. Results:A total of 22 patients were enrolled. There were 8 patients in TMF-FTSG group, 4 males and 4 females, aged (68.3±9.7) years. There were 6 patients in PMMF group, 5 males and 1 female, aged (65.8±7.8) years. There were 3 males and 5 females in ALTF group, aged (63.8±5.4) years. There were 12 cases of squamous cell carcinoma, 8 cases of basal cell carcinoma and 2 cases of adenoid cystic carcinoma. The size of soft tissue defect after tumor resection in TMF-FTSG group, PMMF group and ALTF group was 4 cm×4 cm-7 cm×8 cm, 4 cm×5 cm-9 cm×9 cm and 5 cm×6 cm-14 cm×9 cm, respectively. And the size of flaps ranged from 5 cm×4 cm to 8 cm×9 cm, from 5 cm×7 cm to 10 cm×10 cm, and from 10 cm×6 cm to 20 cm×9 cm, respectively. All donor sites and 20 recipient sites recovered in stage Ⅰ, 2 recipient sites recovered in stage Ⅱ. The patients were monitored for a mean of (27.2 ±13.0) months. During the period of follow-up, one patient, reconstructed with PMMF, died 13 months after surgery due to local tumor recurrence, while the others did not experience metastasis or recurrence. In TMF-FTSG group, the mouth opening was (3.60±0.36) cm 3 months after operation and (3.84±0.15) cm before operation, with no significant difference ( P>0.05). The UW-QOL scores of appearance, mood and anxiety in the three groups 1 year after operation were higher than those before operation ( P<0.05), and the one year after operation’s scores of activity and shoulder were lower than those before operation ( P<0.05). The UW-QOL scores of pain and recreation in TMF-FTSG group one year after operation were higher than those before operation ( P<0.05), the other two groups were also higher than those before operation, but the difference was not statistically significant ( P>0.05). There was no significant difference in the UW-QOL scores of swallowing, chewing, speech, taste, and saliva in the three groups at one year after operation and before operation ( P>0.05). Conclusion:In the repair of tissue defects after operation of malignant tumors in the orbital region, three distinct types of tissue flaps can be utilized to repair tissue defects. TMF-FTSG has certain advantages for patients with minor bone defects, whereas ALTF and PMMF are more appropriate for patients with extensive tissue loss. PMMF is an effective method of repair for patients with a history of radiotherapy and poor vascular health in the recipient area.
7.Retrospective analysis of three different types of tissue flaps in reconstruction of tissue defects of orbital region
Xubin WU ; ·Maimaiti ABUDUKELIMUJIANG ; Zhitao YAO ; ·Saimaiti ADILIJIANG ; ·Tuerxun JULAITI ; Wei AN ; Tairan DING ; Simin ZHANG ; ·Tuerdi MAIMAITITUXUN
Chinese Journal of Plastic Surgery 2023;39(5):479-489
Objective:To investigate the clinical effect of three different tissue flaps in repairing patients with orbital region tissue loss after enlarged resection of malignant tumors in the orbital region, as well as the indication.Methods:Retrospective analysis of data of patients with malignant tumors in the orbital region treated in the Department of Oral and Maxillofacial Trauma and Orthognathic Surgery, the First Affiliated Hospital of Xinjiang Medical University (Affiliated Stomatological Hospital) between January 2017 and December 2021. All patients underwent extensive resection of periorbital malignant tumors and enucleation of orbital contents, depending on defects in periorbital soft/hard tissues and orbital contents, temporalis myofascial flap combined with full thickness skin grafts (TMF-FTSG group), modified pectoralis major myocutaneous flap (PMMF group), and free anterolateral thigh flap (ALTF group) were used to repair the tissue defect. The wound healing and complications of the donor and recipient areas were followed up after operation, and degree of mouth opening in the TMF-FTSG group was compared at 3 months after operation and before operation. The University of Washington quality of life scale (UW-QOL) score was compared among the three groups before and 1 year after operation (a total of 12 items, each item was assigned from 0 to 100 points, the higher the score, the better the recovery). Statistical software SPSS 26.0 was used to analyze the data. The measurement data were expressed as Mean±SD, and the paired t-test was used to compare the preoperative and postoperative data within the group, the difference was statistically significant at a P value less than 0.05. Results:A total of 22 patients were enrolled. There were 8 patients in TMF-FTSG group, 4 males and 4 females, aged (68.3±9.7) years. There were 6 patients in PMMF group, 5 males and 1 female, aged (65.8±7.8) years. There were 3 males and 5 females in ALTF group, aged (63.8±5.4) years. There were 12 cases of squamous cell carcinoma, 8 cases of basal cell carcinoma and 2 cases of adenoid cystic carcinoma. The size of soft tissue defect after tumor resection in TMF-FTSG group, PMMF group and ALTF group was 4 cm×4 cm-7 cm×8 cm, 4 cm×5 cm-9 cm×9 cm and 5 cm×6 cm-14 cm×9 cm, respectively. And the size of flaps ranged from 5 cm×4 cm to 8 cm×9 cm, from 5 cm×7 cm to 10 cm×10 cm, and from 10 cm×6 cm to 20 cm×9 cm, respectively. All donor sites and 20 recipient sites recovered in stage Ⅰ, 2 recipient sites recovered in stage Ⅱ. The patients were monitored for a mean of (27.2 ±13.0) months. During the period of follow-up, one patient, reconstructed with PMMF, died 13 months after surgery due to local tumor recurrence, while the others did not experience metastasis or recurrence. In TMF-FTSG group, the mouth opening was (3.60±0.36) cm 3 months after operation and (3.84±0.15) cm before operation, with no significant difference ( P>0.05). The UW-QOL scores of appearance, mood and anxiety in the three groups 1 year after operation were higher than those before operation ( P<0.05), and the one year after operation’s scores of activity and shoulder were lower than those before operation ( P<0.05). The UW-QOL scores of pain and recreation in TMF-FTSG group one year after operation were higher than those before operation ( P<0.05), the other two groups were also higher than those before operation, but the difference was not statistically significant ( P>0.05). There was no significant difference in the UW-QOL scores of swallowing, chewing, speech, taste, and saliva in the three groups at one year after operation and before operation ( P>0.05). Conclusion:In the repair of tissue defects after operation of malignant tumors in the orbital region, three distinct types of tissue flaps can be utilized to repair tissue defects. TMF-FTSG has certain advantages for patients with minor bone defects, whereas ALTF and PMMF are more appropriate for patients with extensive tissue loss. PMMF is an effective method of repair for patients with a history of radiotherapy and poor vascular health in the recipient area.
8.Reconstruction of defects of distal-and-middle segments of finger pulps with striated wrist transverse flap carrying superficial palmar branch of radial artery with sensory nerve
Haizhou NIU ; Min WU ; Jianzhong GUAN ; Zhongbing HAN ; Yangyang LIU ; Xubin GAO ; Kuankuan ZHANG
Chinese Journal of Microsurgery 2022;45(1):41-45
Objective:To evaluate the clinical effect of striated free wrist transverse flap pedicled with superficial palmar branch of radial artery carrying sensory nerve in repairing pulp defect of middle-and-distal segments of fingers.Methods:From February 2019 to March 2021, the data of 20 patients with defects of middle-and-distal finger segment were collected. The defects were repaired with striated free wrist transverse flaps pedicled with superficial palmar branch of radial artery. The defects sized were 2.0 cm×1.5 cm-4.0 cm×1.5 cm, and the flaps sized were 2.5 cm×2.0 cm-4.5 cm×2.0 cm. The flap carried metacarpal cutaneous branch of median nerve for the reconstruction of the sensation of finger pulps. The donor sites were directly sutured. After operation, the patients were evaluated according to the shape, sensation and functional recovery of the repaired fingers through outpatient visits and reviews via WeChat.Results:All 20 flaps survived and the wounds healed well. All patients entered regular follow-up for 6-12(average, 8) months. The colour of the flaps was close to the finger skin, without bloating flaps. The flaps were soft in good shapes and function. TPD were 6-11 mm, at 8 mm in average. The scars at the donor sites were hidden and the wrist function was not affected. According to the Trial Evaluation Standard of Upper Limb Function of Hand Surgery Society of Chinese Medical Association, 16 patients were classified as excellent and 4 as good.Conclusion:The striated transverse wrist flap with radial artery palmar superficial branch and sensory nerve offers many advantages, such as a good texture, hidden donor site, convenient flap harvesting, good recovery of sensation, etc. More clinical studies and the promotion of the technique are expected.
9.Application of arterial end-to-end and end-to-side anastomosis in superficial branch of the superficial circumflex iliac artery perforator flap transfer
Yangyang LIU ; Min WU ; Xubin GAO ; Jianzhong GUAN
Chinese Journal of Microsurgery 2021;44(5):517-520
Objective:To explore a comparative study of arterial end-to-end and end-to-side anastomosis in superficial branch of the superficial circumflex iliac artery(SCIA) perforator flap transfer.Methods:Between November, 2019 and December, 2020, 21 patients with the soft tissue defects in the limbs were repaired with superficial branch of the SCIA perforator flaps. The size of flaps ranged from 3.5 cm×7.0 cm to 9.0 cm×18.0 cm. According to the upper or anterior wall of the main artery in the recipient area having branches that matched the flap artery, 2 groups were established. End-to-end group: 10 cases were anastomosed end-to-end between the flap artery and branch of the main artery in the recipient area; End-to-side group: 11 cases were anastomosed end-to-side between the flap artery and side mouth of the main artery in the recipient area. The vein of flap was anastomosed end-to-end with the accompanying vein to the main artery in the recipient area. All of the donor sites were sutured directly. All patients were followed-up for 6-12 months and the survival of the perforator flap, the appearance and function of the perforator flap and the donor site were observed. All data of the 2 groups were conducted statistical analyzed. P<0.05 was statistically significant. Results:All 10 flaps in end-to-end group survived successfully. In end-to-side group, 2 cases had venous crisis in 11 cases of flaps,the exploration revealed venous thrombosis, and the arterial end-to-side anastomosis had smooth blood flow had embolism. One flap survived after re-anastomosis of the vein, and 1 flap was changed to a pedicled abdominal flap during the re-venous crisis. The postoperative follow-up was 6 months to 1 year. The appearance and function of the flap and donor site were satisfactory, without difference between the 2 groups. The SCIA superficial branch artery caliber, recipient artery branch or lateral caliber was not statistically different between the 2 groups( P>0.05). The time of anastomosis for end-to-end group was[(16.70±1.34) min]. It was lower than that of anastomosed end-to-side group[(23.73±1.68) min]. The difference was statistically significant( P<0.01). Conclusion:In superficial branch of the SCIA perforator flap transfer, if the upper or anterior wall of the main artery in the recipient area has a branch that matches the flap artery, the flap artery should first be anastomosed with its end. Because it dose not required to make a side port, and makes the operation more convenient with a short anastomosis time; Otherwise, perform end-to-side anastomosis with the main artery of the recipient site.
10.Effects of Calcium on the Stability of VWF-A2 Domain by Molecular Dynamics Simulation
Xubin XIE ; Wenping LIU ; Jianhua WU ; Ying FANG
Journal of Medical Biomechanics 2018;33(3):E248-E254
Objective To investigate the effect of calcium on the stability of VWF-A2 domain. Methods The crystal structures of A2 (not containing calcium) and A2/Ca2+ (with calcium bound) were downloaded from protein data bank. For A2 domain, the conformational changes, unfolding pathway differences and the exposure degree variance of cleavage sites caused by calcium binding were observed and analyzed by steered Molecular Dynamics simulations under constant force. Results The unfolding pathway of A2 domain and exposure process of cleavage sites were force-dependent. Calcium binding did not affect the unfolding process of A2 in the early stage. As the conformational rearrangement of α3β4-loop reduced its localized dynamic properties, the movement among β1-β4-β5 strands was restrained, which suppressed its further unfolding to stay in the intermediate steady state and delayed the cleavage-site exposure. Conclusions Stretch force could induce β5 strand of A2 unfolding and the cleavage-site exposure, while calcium binding inhibited ADAMTS13 proteolysis efficiency through stabilizing A2 hydrophobic core and covering its cleavage sites. These results way help to understand how ADAMTS13 cleavages the VWF-A2 domain and regulates the hemostatic potential of VWF, and further provide useful guidance on the design of related anti-thrombus drugs.


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