摘要:目的:研究生物降解聚DL乳酸(PDLLA)自锁式捆绑带固定骨折的生物力学性能。方法:80只新西兰大白兔随机分为两组,建立股骨干非负重骨折动物模型,应用生物降解自锁式捆绑带固定骨折为实验组,钢丝固定骨折为对照组,分别于术后1、4、8、12周行生物力学检查进行比较。结果:捆绑带组在术后4、8、12周均比钢丝组的弯曲强度高,但4周、12周时Pgt;005,无统计学差异,8周时Plt;005,提示有统计学差异。离体同种固定物不同时间段抗拉强度自身比较:钢丝固定术后4阶段抗拉强度比较Pgt;005,任何两两比较都没有统计学差异,抗拉强度未随术后时间延长发生明显下降。捆绑带固定术后4周与术后1周比较Pgt;005,抗拉强度无明显降低,但术后8周和术后12周时Plt;005,抗拉强度明显下降。结论:生物降解自锁式捆绑带在非负重骨折治疗中可发挥良好的固定作用。生物降解自锁式捆绑带降解时,应力传导促进了骨折的愈合。Abstract: Objective: To study the biomechanics function of selflocking cerclage band made of biodegradable material polyDLlactic acid (PDLLA) in the fixation of fractures. Methods: Eighty rabbits were divided into two groups. Femur fracture models were made. Fractures were fixed using biodegradable selflocking cerclage band in experimental group and metal fixation material in control group. The biomechanics was analyzed and compared after 1, 4, 8 and 12 weeks respectively． Results: The bending strength of experimental group is more ber than that of control group after 4, 8 and 12 weeks, but it was not statistically significant at 4 and 12 weeks (Pgt;005). It was statistically significant at 8 weeks (Plt;005). The tensile strength of the same cerclage instrument was compared at different stage in vitro, and the result of the control group was not statistically significant at the four stage (〖WTBX〗P〖WTBZ〗gt;005). Regarding the changes of tensile strength of the cerclage instrument at different stage, the result of the experimental group was not statistically significant after 1 and 4 weeks (Pgt;005). However, the decrease of tensile strength was statistically significant after 8 and 12 weeks (Plt;005). Conculsion: Biodegradable selflocking cerclage band could be used in thetreatment of nonweightbearing fractures. The stress force conducting promotes healing of fracture when the selflocking biodegradable cerclage band degrades.
Objective To select levorotatory polylactic acid (PLLA) and polycaprolactone (PCL) as the main materials, use electrostatic spinning and ultrasonic broaching processing technique to prepare a similar to natural vascular diameter gradient structure of large diameter artificial blood vessels, and evaluate its potential applications. Methods Using PLLA and PCL as raw materials, through the electrospinning process, using core shafts of different diameters as collection devices, artificial vascular materials with a natural-like structure were constructed. Using end to end anastomosis method to experimental pig thoracic descending aorta replacement of artificial blood vessels. Results Computed tomography angiography (CTA) results showed that the artificial vascular graft was patent at 1 week and 6 weeks after operation. Animal experimental pathology examination revealed, artificial blood vessels unobstructed, the lining of endothelial cells, and elastic fiber, roughly three layer structure formed similar natural aorta. Artificial blood vessel wall visible elastic fibers, elastic fibers and collagen fibers with natural blood vessels distribution was similar. Immunohistochemical examination showed that the artificial blood vessels had a strong immune response to ERG staining, Actin staining, and Vementin staining. Scanning electron microscopy showed that endothelial cells were formed in the inner layer of the artificial blood vessel. Conclusion PLLA and photo as raw material, the use of electrostatic spinning and ultrasonic reaming technology preparation of large diameter artificial blood vessels, imitation of natural structure may have potential good flow resistance, good endothelial and may have induced in-situ natural function of angiogenesis.
ObjectiveTo explore the effect of silk fibroin/poly(L-lactic acid-co-e-caprolactone) [SF/P(LLA-CL)] nanofibrous scaffold on tendon-bone healing of rabbits.MethodsSF/P(LLA-CL) nanofibrous scaffold was fabricated by electrospinning methods. The morphology of the scaffold was observed by scanning electron microscope (SEM). Pre-osteoblasts MC3T3-E1 cells were seeded on the scaffold and cultured for 1, 3, and 5 days. Cell adhesion and proliferation were also observed by SEM. Meanwhile, twenty-four New Zealand white rabbits were randomly divided into the autogenous tendon group (control group) and the autogenous tendon wrapped with SF/P(LLA-CL) scaffold group (experimental group), with twelve rabbits in each group. An extra-articular model was established, the effect was evaluated by histological examination and mechanical testing.ResultsThe morphology of SF/P(LLA-CL) nanofibrous scaffold was random, with a diameter of (219.4±66.5) nm. SEM showed that the MC3T3-E1 cells seeded on the scaffold were in the normal shape, growing well, and proliferating with time course. The results of histological examination showed that inflammatory cells infltrated into the graft-host bone interface at 6 weeks after operation in both groups. Besides, the width of interface showed no significant difference between groups. At 12 weeks after operation, protruding new bone tissue could be observed at the interface in the experimental group, while scar tissue but no new bone tissue could be seen at the interface in the control group. Mechanical testing showed that there was no significant difference in the failure load and the stiffness between groups at 6 weeks after operation (P>0.05). The failure load and the stiffness in the experimental group were significantly higher than those in the control group at 12 weeks after operation (P<0.05).ConclusionThe SF/P(LLA-CL) nanofibrous scaffold has good cell biocompatibility and can effectively promote tendon-bone healing, thus providing new method for modifying graft for ACL reconstruction in the clinical practice.
ObjectiveTo investigate the effect of electrospun chitosan/polylactic acid (ch/PLA) nerve conduit for repairing peripheral nerve defect in rats. MethodsNerve conducts loaded with ch/PLA was made by the way of electrospun. The mechanical property, hydrophility, biocompatibility were tested, and the scanning electron microscope was used to observe the ultrastructure. The same experiments were also performed on pure PLA nerve conducts as a comparison. Then, 54 Sprague Dawley rats were divided into 3 groups randomly, 18 rats in each group. Firstly, the 10 mm defects in the right sciatic nerves were made in the rats and were respectively repaired with ch/PLA (group A), autografts (group B), and no implant (group C). At 4, 8, and 12 weeks after operation, general observations, sciatic functional index (SFI), electrophysiological evaluation, wet weight of gastrocnemius and soleus muscles, histological examination, immunohistological analysis, and transmission electron microscopy were performed to evaluate the effects. ResultsCompared with pure PLA nerve conducts, the addition of chitosan could improve the mechanical property, hydrophility, biocompatibility, and ultrastructure of the nerve conducts. At 4 weeks postoperatively, the regenerated nerve bridged the nerve defect in group A. The SFI improved gradually in both group A and group B, showing no significant difference (P>0.05). Compound muscle action potentials and nerve conduction velocity could be detected in both group A and group B at 8 and 12 weeks after operation, and significant improvements were shown in both groups (P<0.05). The wet weight and myocyte cross section of gastrocnemius and soleus muscles showed no significant difference between group A and group B (P>0.05), but there was significant difference when compared with group C (P<0.05) at 12 weeks postoperatively. Immunohistological analysis revealed that S-100 positive Schwann cells migrated in both group A and group B, and axon also regenerated by immunohistological staining for growth associated protein 43 and neurofilaments 160. Transmission electron microscopy showed no significant difference in the diameter of nerve fiber between group A and group B (P>0.05), but the thickness of myelin sheath in group A was significantly larger than that in group B (P<0.05). ConclusionThe electrospun ch/PLA nerve conduits can effectively promote the peripheral nerve regeneration, and may promise an alternative to nerve autograft for repairing peripheral nerve defect.
OBJECTIVE To confirm membrane-guided tissue regeneration in the healing course of segmental bone defects and study the mechanism. METHODS Segmental, 1 cm osteoperiosteal defects were produced in both radii of 12 rabbits. One side was covered with hydroxyapatite/polylactic acid(HA/PLA) membrane encapsulated as a tube. The contralateral side served as an untreated control. Healing courses were detected by radiographic and histologic examinations. RESULTS All control sides showed nonunion, whereas there were consistent healing pattern in test sides. CONCLUSION Membrane technique can promote bone regeneration.
The poly-lactic acid membrane is characterized by its non-toxicity, non-carcinogenic and the property of degradation in the body in animal experiment, this membrane was wrapped around the tenorrhaphy site. The results showed that 3 to 9 weeks after operation there was an intact space surrounding the tendon, and the membrane began to degradate at 24 weeks, might achieve the purpose to prevent the formation of adhesion. From Nov. 1985 to Sept. 1989, this membrane was applied to 20 tendons of 14 patients. The follow-up results showed that the satisfactory rate was 81.8% .the indications of using poly-lacic acid membrane were primary, delayed primary and secondary suture of flexor tendon injuries in areas of the fingers.
Objective To determine the incidence of vitamin B1 deficiency in critically ill patients, to compare vitamin B1 levels between septic and non-septic patients, and to explore the relationship between vitamin B1 levels and lactate levels. Methods Using a retrospective study method, critically ill patients admitted to the Department of Intensive Care of Nanjing Drum Tower Hospital from February 2022 to November 2022 were included in the study, and the patients were divided into sepsis and non-sepsis groups according to the admission diagnosis, and the differences in the vitamin B1 levels of the patients between the two groups were analyzed, as well as the correlation between the vitamin B1 levels and the lactic acid levels. Results There was a significant difference in serum vitamin B1 levels between the sepsis patients and the non-sepsis patients [(1.6±0.3)ng/mL vs. (2.1±0.2)ng/mL, P=0. 009]. For all patients, there was no correlation between vitamin B1 levels and lactate levels. But when the patient was in a hyperlactate state (lactate level ≥2 mmol/L), vitamin B1 levels were significantly negatively correlated with lactate levels (r=–0. 229, P=0. 004). Conclusions Vitamin B1 deficiency is prevalent in critically ill patients and is strongly correlated with whether or not the patient is septic. Vitamin B1 levels are significantly and negatively correlated with lactate levels when the patient's lactate level is ≥2 mmol/L.
ObjectiveTo investigate the influences of lactic acid (LA), the final degradation product of polylactic acid (PLA) on the prol iferation and osteoblastic phenotype of osteoblast-l ike cells so as to provide theoretical basis for bone tissue engineering. MethodsRos17/2.8 osteoblast-l ike cells were harvested and divided into 3 groups. In groups A and B, the cells were cultured with the medium containing 4, 8, 16, 22, and 27 mmol/L L-LA and D, L-LA, respectively. In group C, the cells were cultured with normal medium (pH7.4). The cell prol iferation was determined with MTT method after 1, 3, and 5 days. The relative growth ratio (RGR) was calculated, and the cytotoxicity was evaluated according to national standard of China. In addition, the alkal ine phosphatase (ALP) activity of cells cultured with medium containing 4 mmol/L L-LA (group A), 4 mmol/ L D, L-LA (group B), and normal medium (group C) after 1 and 5 days were detected with ALP kits, and the relative ALP ratio (RAR) was calculated; after 21 days, the calcium nodules were tested with von Kossa staining method, and were quantitatively analyzed. ResultsWhen LA concentration was 4 mmol/L, the mean RGR of both groups A and B were all above 80%, and the cytotoxic grades were grade 0 or 1, which meant non-cytotoxicity. When LA concentration was 8 mmol/L and 16 mmol/ L, groups A and B showed cytotoxicity after 5 days and 3 days, respectively. When LA concentration was above 22 mmol/L, cell prol iferations of groups A and B were inhibited evidently after 1-day culture. At each LA concentration, RGR of group A was significantly higher than that of group B at the same culture time (P<0.05) except those at 4 mmol/L after 1-day and 3-day culture. After 1 day, the RAR of group A was significantly higher than that of group B on 1 day (144.1%±3.2% vs. 115.2%±9.8%, P<0.05) and on 5 days (129.6%±9.8% vs. 78.2%±6.9%, P<0.05). The results of von Kossa staining showed that the black gobbets in group A were obviously more than those of groups B and C. The staining area of group A (91.2%±8.2%) was significantly higher than that of groups B (50.3%±7.9%) and C (54.2%±8.6%) (P<0.05). ConclusionThe concentration and composition of LA have significant effects on the cell proliferation and osteoblastic phenotype of osteoblast-l ike cells.
Objective To study the result of using nerve conduit coated with chitin and filled with a guide-fiber to repair peripheral nerve defect. Methods Twenty-four female adult SD rats were made the model of 14 mm-gap on bilateral sciatic nerve under sterile condition. The rats were randomly divided into 4 groups(n=6),group A: polymer polyglycolic-lactic acid(PGLA) nerve conduit coated with chitin and filled with a guide-fiber as experimental group to repair 14 mm gap of rat sciatic nerve；group B: PGLA nerve conduit coated with chitin； group C: PGLA nerve conduit； group D: autograft (control group). The repair result was evaluated by normal observation, EMG testing and S-100 histological immunostaining analysis 4 and 12 weeks after operation.Results Four weeks after the operation，there were new regenerated immature fibers in groups A,B and C, 12 weeks after the operation, the regenerated nerve fibers were seen to have bridged the gap. There were myelinated fibers equably distributed and rarely newgenerated nerve fibers in distal parts of group D. The repair result of PGLA nerve conduit coated with a chitin and filled with guide-fiber was better than that of groups B and C（Plt;0.05）. There was significant difference of nerve fiber diameter，thickness of myelin sheath and fiber density in group D from those in groups A, B and C（Plt;0.05），but there were degenerative changes such as vacuoles insheaths and myelin separation in proximal and few new regenerated nerve fibers in distal parts of group D. Conclusion PGLA nerve conduit coated with chitin and filled with a guide-fiber offers a possible substitute for the repair of peripheral nerve defect.
Objective To prepare collagen-chitosan /nano-hydroxyapatite-collagen-polylactic acid (Col-CS/ nHAC-PLA) biomimetic scaffold and to examine its biocompatibility so as to lay the foundation for its application on the treatment of osteochondral defect. Methods PLA was dissolved in dioxane for getting final concentration of 8%, and the nHAC power was added at a weight ratio of nHAC to PLA, 1 ∶ 1. The solution was poured into a mold and frozen. CS and Col were dissolved in 2% acetum for getting the final concentrations of 2% and 1% respectively, then compounded at a weight ratio of CS to Col, 20 ∶ 1. The solution was poured into the frozen mold containing nHAC-PLA, and then biomimetic osteochondral scaffold of Col-CS/nHAC-PLA was prepared by freeze-drying. Acute systemic toxicity test, intracutaneous stimulation test, pyrogen test, hemolysis test, cytotoxicity test, and bone implant test were performed to evaluate its biocompatibility. Results Col-CS/nHAC-PLA had no acute systemic toxicity. Primary irritation index was 0, indicating that Col-CS/nHAC-PLA had very slight skin irritation. In pyrogen test, the increasing temperature of each rabbit was less than 0.6℃, and the increasing temperature sum of 3 rabbits was less than 1.3℃, which was consistent with the evaluation criteria. Hemolytic rate of Col-CS/nHAC-PLA was 1.38% (far less than 5%). The toxicity grade of Col-CS/nHAC-PLA was classified as grade I. Bone implant test showed that Col-CS/nHAC-PLA had good biocompatibility with the surrounding tissue. Conclusion Col-CS/ nHAC-PLA scaffold has good biocompatibility, which can be used as an alternative osteochondral scaffold.