Three-dimensional finite element analysis of a new horizontal screw-screw crosslink in posterior atlantoaxial internal fixation / 中国组织工程研究

BACKGROUND:The addition of traditional rod-rod fixation for atlantoaxial joint disease to C1-C2 pedicle screw-rod fixation(C1-C2 PSR)can provide stronger anti-rotation stability for screw/rod fixation,but there is a risk of installation difficulties,impact on bone graft bed,and spinal cord injury.The new horizontal screw-screw crosslink(hS-S CL)designed by the authors can effectively overcome the above shortcomings,but its biomechanical properties are unclear. OBJECTIVE:To analyze biomechanical properties of new horizontal screw-screw crosslink in C1-C2 PSR by three-dimensional finite element analysis. METHODS:CT thin layer scanning data were collected from the occipital base to the axis(C0-2)of one adult healthy male volunteer.The atlantoaxial finite element models were established respectively:the normal group,the unstable group,the non-crosslink group(unstable+C1-C2 PSR),and the crosslink group(C1-C2 PSR+hS-S CL).Range of motion and Von Miss Stresses in flexion and extension,lateral flexion and rotation of the four groups were calculated by applying 1.5 Nm torque to each finite element model,and the stress cloud was extracted. RESULTS AND CONCLUSION:(1)Range of motion of the unstable group was increased by 43.8%-78.7%compared with the normal group,and the range of motion of the internal fixation groups was 90.2%-98.7%lower than that of the unstable group under six conditions.The range of motion of the crosslink group and the non-crosslink group was basically the same in flexion and extension states,but in lateral flexion and rotation states,the range of motion of the crosslink group decreased 34.3%-43.8%and 78.6%-79.1%,respectively,compared with the non-crosslink group,and range of motion decreased most obviously in rotation state.(2)The stress peak of the internal plant model:The maximum stress of the crosslink group was generally smaller than that of the non-crosslink group,and the stress peak value of all the internal fixation groups was the lowest when the extension was carried out.(3)The stress cloud of internal plants showed that there was no obvious stress concentration phenomenon in the internal fixation,and the main stress distribution areas were the screw root and bone joint,and the crosslink ends were the screw tail groove or the joint rod joint.(4)The new horizontal screw-screw crosslink can obviously improve the anti-rotation stability of internal fixation and it can share part of the pressure in the three-dimensional motion direction of the internal fixation system and reduce the maximum stress of the internal plants.However,the stress distribution is obvious at both ends of the crosslink,and this part may be prone to fracture of the crosslink.

Biomechanical analysis of new horizontal screw-screw crosslink in C1-C2 pedicle screw-rod fixation / 中国组织工程研究

BACKGROUND:Posterior atlantoaxial pedicle screw rod internal fixation is the main method for treating atlantoaxial dislocation,and the horizontal crosslink plays an important role in the antirotation ability of the internal fixation system.The new horizontal screw-screw crosslink can effectively overcome the disadvantages of traditional horizontal crosslink,such as inconvenient installation,impact on bone grafting bed,and potential spinal cord injury.However,the biomechanical properties of the new horizontal screw-screw crosslink with different installation modes are still unclear. OBJECTIVE:To investigate the biomechanical characteristics of new different installation modes of horizontal screw-screw crosslink in the C1-C2 pedicle screw-rod fixation and to provide a theoretical basis for optimal installation mode. METHODS:Six fresh human occipitocervical specimens were divided into the intact state group(group A),and the atlantoaxial instability model of type Ⅱ odontoid fracture was established based on the intact state group as the instability group(group B).The C1-C2 pedicle screw-rod fixation was performed on each specimen based on the instability group(group C).In group C,different installation modes of horizontal screw-screw crosslink were successively installed in each specimen,including upper transverse connection(two atlas screw tails)as group D,lower transverse connection(two axis screw tails)as group E,diagonal transverse connection(upper left and lower right for group F,lower left and upper right for group G),and cross transverse connection as group H.The specimen models were tested in order of flexion,extension,lateral flexion and lateral rotation on a three-dimensional motion machine,and the atlantoaxial range of motion of each group of specimens was obtained.Repeated measure analysis of variance was used to evaluate the biomechanical properties of each group. RESULTS AND CONCLUSION:(1)Under six states,the range of motion of groups A,C,D,E,F,G and H was smaller than that of group B,and there were statistically significant differences(P＜0.05).(2)In the flexion and extension states,there was no significant difference among the five types of horizontal screw-screw crosslink groups(P＞0.05).(3)In the left and right rotation directions,there were significant differences in D and E groups compared with F,G and H groups(P＜0.05);there were no significant differences between D and E groups,and F and G groups(P＞0.05),and there were no significant differences in F and G groups compared with H group(P＞0.05).(4)In conclusion,under flexion-extension states,the biomechanical stability of five types of horizontal screw-screw crosslink groups was similar,but under the rotation state,the stability of diagonal horizontal screw-screw crosslink group and cross horizontal screw-screw crosslink group was obviously better than that of transverse horizontal screw-screw crosslink group;however,the stability of diagonal horizontal screw-screw crosslink group is similar to the cross horizontal screw-screw crosslink group,so the former is more worthy of clinical recommendation.

Properties of decellularized rabbit carotid artery with two different cross-linked technologies: A comparative study / 中南大学学报(医学版)

Objective:To compare the properties between decellularized rabbit carotid artery with different cross-linked technologies.Methods:The decellularized rabbit carotid arteries were randomly divided into a photo-oxidation group and a procyanidins group.One group was cross-linked with photo-oxidation and the other group was cross-linked with procyanidins.The in vitro or in vivo properties of the two groups were evaluated by testing heat-shrinking temperature,max tensile strength and the max elongation or by testing tissue structure,inflammatory reaction and calcification degree.Results:The heat-shrinking temperature,max tensile strength and the max elongation were similar in the two groups (P＞0.05).The tissue structure and inflammatory reaction were also similar in the two groups.Mthough the result of Von-Kossa calcium salt stain was slightly different,the calcium content was lower in the procyanidins group than that in the photo-oxidation group (P＜0.05).Conclusion:The grafts by two cross-linked technologies show excellent mechanical capability,lower immunogenicity,good biological stability and anti-calcification ability.The procyanidins group shows a better anti-calcification property than the photo-oxidation group.

Preparation of immobilized Lactobacillus plantarum agent for silage / 生物工程学报

Lactic acid bacteria and cellulose degrading bacteria play an important role in fermentation process of silage, because they can prevent the rancidity and increase the nutritive value of silage. But the propagation of lactic acid bacteria will inhibit the activity of cellulose degrading bacteria in the silage fermentation system. This problem can be solved by releasing lactic acid bacteria and cellulose degrading bacteria in different time. Therefore, we immobilized lactic acid bacteria as a microbial agent for sustained release. Firstly, the optimal balling concentration of the composite immobilized carrier and composite immobilized carrier were obtained by immobilization of blank balls and corncob adsorbed Lactobacillus plantarum S1 respectively. The best immobilization condition of L. plantarum S1 was obtained by comparing the immobilized rate and balling effect of two kinds of balls, which were embedded by sodium alginate (SA), CMC-Na and embedded-crosslinked by SA, CMC-Na, polyvinyl alcohol (PVA). The results showed that the best balling concentration was achieved by using 6% PVA+0.4% SA+0.3% CMC-Na for embedding-crosslinking and 1.2% SA+0.5% CMC-Na for direct embedding respectively. In addition, comparing with the mechanical strength and embedding rate of five kinds of immobilization process, the best immobilized process was obtained by adding of the mixture of immobilized carriers (1.2%SA+ 0.5%CMC-Na) and corncob adsorbed L. plantarum S1 slowly into 4% CaCl₂ for 24 hours. The corncob adsorption and SA embedding methodology can effectively increase the embedding efficiency of Lactobacillus plantarum S1.

The Role of the Lysyl Oxidases in Tissue Repair and Remodeling: A Concise Review

Tissue injury provokes a series of events containing inflammation, new tissue formation and tissue remodeling which are regulated by the spatially and temporally coordinated organization. It is an evolutionarily conserved, multi-cellular, multi-molecular process via complex signalling network. Tissue injury disorders present grievous clinical prob-lems and are likely to increase since they are generally associated with the prevailing diseases such as diabetes, hyper-tension and obesity. Although these dynamic responses vary not only for the different types of trauma but also for the different organs, a balancing act between the tissue degradation and tissue synthesis is the same. In this process, the degradation of old extracellular matrix (ECM) elements and new ones' synthesis and deposition play an essential role, especially collagens. Lysyl oxidase (LOX) and four lysyl oxidase-like proteins are a group of enzymes capable of catalyzing cross-linking reaction of collagen and elastin, thus initiating the formation of covalent cross-links that insolubilize ECM proteins. In this way, LOX facilitates ECM stabilization through ECM formation, development, maturation and remodeling. This ability determines its potential role in tissue repair and regeneration. In this review, based on the current in vitro, animal and human in vivo studies which have shown the significant role of the LOXs in tissue repair, e.g., tendon regeneration, ligament healing, cutaneous wound healing, and cartilage remodeling, we focused on the role of the LOXs in inflammation phase, proliferation phase, and tissue remodeling phase of the repair process. By summarizing its healing role, we hope to shed light on the understanding of its potential in tissue repair and provide up to date therapeutic strategies towards related injuries.

Preparation and quality evaluation of starch microspheres of diclofenac sodium / 中国药学杂志

OBJECTIVE: To prepare starch microspheres of diclofenac sodium by inverse crosslink emulsification method. METHODS: Mean particle size and encapsulation efficiency of starch microspheres were used as indicators, single factor and orthogonal design methods were performed for optimizing preparation process and formulations of starch microspheres. The appearance and structure of the microspheres were researched by optical microscope, transmission electron microscope, infrared spectroscopy and differential thermal analyzer. In vitro drug release behavior was investigated by dialysis method. RESULTS The preparation conditions optimized by orthogonal design; the concentration of starch 10%, crosslinking temperature 55℃, dosage of cross-linking agent 0.2 g, the volume ratio of oil phase and water 5:1, amount of emulsifier 5 mL, cross-linking time 60 min. Starch microsphere obtained by above condition has an average particle size of 9 μm, appearance is irregular spherical shape, and encapsulation efficiency was 67.52%. Results of IR spectra and DTA curves showed that starch cross-links have happened. CONCLUSION In vitro releasing curve showed that the diclofenac sodium starch microspheres have good sustain release effect, drug release complies with the Weibull equation.

Comparison of biomechanical properties by different posterior fixation methods with or without crosslink for fixing thoracolumbar fractures / 医用生物力学

Objective To compare the biomechanical differences in 3 posterior fixation methods with or without crosslink for treatment of thoracolumbar fractures, so as to find the optimal posterior fixation methods. Methods On the basis of the validated finite element model of T12-L2 segments to simulate L1 vertebra burst fracture, the superior 1/2 cortical bone of T12 segment was removed and the superior 1/2 cancellous bone was assigned with the material damage property of cancellous bone. Then 6 thoracolumbar fracture models by intermediate unilateral pedicle screw fixation without or with crosslink (Model A1, A2), traditional short-segment pedicle screw fixation without or with crosslink (Model B1, B2), intermediate bilateral pedicle screw fixation without or with crosslink (Model C1,C2) were established, respectively. The range of motion (ROM) as well as the maximum Von Mises stress of the pedicle screw and rod for 6 models under various physiological loading conditions were compared. Results The ROM under flexion-extension and lateral bending in Model A and Model C was obviously smaller than that of Model B. Under flexion-extension, no significant difference was found in ROM between Model A and Model C; under lateral bending, the ROM of Model C was smaller than that of Model A. The stress was concentrated in the root of upper screw and the rob located between upper screw and intermediate screw; the maximum stress of upper screw in Model C was smaller than that in Model A and Model B. The crosslink could increase the stability of all fixation groups under axial rotation stress condition, and decrease the maximum stress on upper screw and rod under axial rotation stress condition, but no significant difference was found under flexion-extension and lateral bending. Conclusions Additional pedicle screws at the level of fracture vertebra can achieve the better biochemical stability. The additional crosslink not only increases the torsional rigidity, but also decreases the maximum torsional stress of the screw and rod, which is a better choice as the treatment of thoracolumbar fractures.

Biomechanical Analysis of a Pedicle Screw-Rod System with a Novel Cross-Link Configuration

STUDY DESIGN: The strength effects of a pedicle screw-rod system supplemented with a novel cross-link configuration were biomechanically evaluated in porcine spines. PURPOSE: To assess the biomechanical differences between a conventional cross-link pedicle screw-rod system versus a novel cross-link instrumentation, and to determine the effect of the cross-links. OVERVIEW OF LITERATURE: Transverse cross-link systems affect torsional rigidity, but are thought to have little impact on the sagittal motion of spinal constructs. We tested the strength effects in pullout and flexion-compression tests of novel cross-link pedicle screw constructs using porcine thoracic and lumbar vertebrae. METHODS: Five matched thoracic and lumbar vertebral segments from 15 porcine spines were instrumented with 5.0-mm pedicle screws, which were then connected with 6.0-mm rods after partial corpectomy in the middle vertebral body. The forces required for construct failure in pullout and flexion-compression tests were examined in a randomized manner for three different cross-link configurations: un-cross-link control, conventional cross-link, and cross-link passing through the base of the spinous process. Statistical comparisons of strength data were analyzed using Student's t-tests. RESULTS: The spinous process group required a significantly greater pullout force for construct failure than the control group (p=0.036). No difference was found between the control and cross-link groups, or the cross-link and spinous process groups in pullout testing. In flexion-compression testing, the spinous processes group required significantly greater forces for construct failure than the control and cross-link groups (p<0.001 and p=0.003, respectively). However, there was no difference between the control and cross-link groups. CONCLUSIONS: A novel cross-link configuration that features cross-link devices passing through the base of the spinous processes increased the mechanical resistance in pullout and flexion-compression testing compared to un-cross-link constructs. This configuration provided more resistance to middle-column damage under flexion-compression testing than conventional cross-link configuration.

Aplicação de transglutaminase microbiana em produtos cárneos processados com teor reduzido de sódio / Application of microbial transglutaminase in processed meat products with reduced content of sodium

O presente artigo compreende uma revisão sobre a aplicação da transglutaminase de origem microbiana (MTGase) em produtos cárneos, elaborados com teor reduzido de sódio. A MTGase tem se mostrado muito eficiente em promover pontes cruzadas entre proteínas, favorecendo a coesão em produtos reestruturados e melhorando a força de géis em produtos cárneos emulsionados, contribuindo para a melhoria de textura e preservando o sabor dos produtos. Tradicionalmente, o cloreto de sódio (NaCl) é adicionado às massas cárneas por desempenhar um papel-chave na solubilização das proteínas miofibrilares. No entanto, o excesso desse mineral tem sido associado aos altos índices de problemas de saúde, como a hipertensão arterial. Como reação a este cenário, a sociedade científica e indústrias ligadas ao setor cárneo têm buscado alternativas que possam atuar na redução do sódio nesses alimentos. Na presente revisão, são relatados estudos recentes sobre a aplicação da MTGase em diversos produtos de origem cárnea, elucidando a importância desse coadjuvante de tecnologia para a pesquisa científica e a aplicação industrial na área de produção de alimentos de conveniência e mais saudáveis.

This article includes a review of the application of microbial transglutaminase (MTGase) in meat products prepared with reduced-sodium. The MTGase has shown to be very efficient in promoting protein cross-bridges, favoring the cohesion restructured products and improving the strength of gels inemulsified meat products, contributing to preserve and improve their texture and flavor. Traditionally sodium chloride (NaCl) is added to pasta cárneas to play a key role in the solubilization of the myofibrillar proteins. However, the excess of this mineral has been linked to high rates of health problems as hypertension. In response to this scenario, scientific society and industries connected to the meat industry has sought alternatives that can acte to reduce the sodium in these foods. In this review, recent studies are reported on the application of MTGase in various products of meat mixture, elucidating the importance of supporting technology for scientific research and industrial application in the production of convenience healthier foods.

In vivo recellularization of decellularized vascular scaffolds cross-linked with anti-CD34 antibody / 第二军医大学学报

Objective: To evaluate the role of decellularized vascular scaffolds coated with anti-CD34 antibodies in capturing endothelial progenitor cells from the circulation to participate in recellularization. Methods: Fresh caprine forelimb arteries were treated with repeated frozen/thawing, ultrahigh pressure and SDS to prepare decellularized vascular scaffolds. After reaction with photochemical crosslinker SANPAH, anti-rabbit CD34 was coated onto the decellularized vascular scaffolds using ultraviolet ray. Twenty New Zealand white rabbits were performed for right lower-abdominal pedicled skin flap, which were supplied by branches of femoral artery. Whole defects (1 cm) were made in femoral arteries and end-to-end anastomosis repaired by 10 cross-linked and 10 non-cross-linked scaffolds in experimental group and control group, respectively. The patency of the pedicle was observed through color and appearance of the flap postoperatively. After transplantation, patency rate and cell seeding were detected by Doppler, DSA, and pathological test. Results:. Flaps of the experimental group had good blood supply after transplantation, while swelling and necrosis could be found in the control group. Doppler and DSA showed that the 7 of 10 cross-linked scaffolds remained patent for 4 weeks and there was no stenonsis, but all the scaffolds were obstructed in the control group after 1 week. Hematoxylin and eosin staining revealed that the inner layers of cross-linked scaffolds were partly covered with endothelial cells four weeks later, and there was no noticeable stenosis. In contrast, thrombosis formation was noticed in the control group and there was no cell coverage one week after operation. Conclusion: Cross-linked scaffolds with anti-CD34 antibodies are superior to bare scaffolds in early postoperative anticoagulation and patency.

Effect of temperature on crosslinking of collagen/chitosan scaffolds with genipin / 中国矫形外科杂志

[Objective]To investigate the changes of pore sizes,crosslinking index,swelling ration,degradation rate,cytotoxicity and biocompatibility of genipin crosslinked collagen/chitosan scaffolds affected by the different crosslinking temperature points.[Method]The freeze-dried collgaen/chitosan scaffolds crosslinked with 0.5% genipin within 24 h were divided into 3 groups by crosslinking temperature:4℃ group,20℃ group and 36℃ group.The characteristics of pore sizes,crosslinking index,swelling ratio,degradation rate,cytotoxicity and biocompatibility were evaluated.Collagen/chitosan scaffolds without crosslinking were chosen as control group.[Result]With the increase of temperature,crosslinking index was increased,but swelling ratio and degradation rate were decreased.In 4℃ group,the crosslinking index was 47.88%?6.4%,the swelling ratio was 721%?46%,and the degradation rate was decreased by 3.95%?6.4% at 4 weeks.In 20℃ group,the crosslinking index was 67.69%?3.6%,the swelling ration was 662%?72%,and the degradation rate was 0.91%?5.9% in 4 weeks.In 36℃ group,the crosslinking index was 70.32%?5.7%,the swelling ration was 635%?27%,and the degradation rate was 0.66%?7.3% at 4 weeks.The above indexes of the three groups were much better than those of control group(P

Identification of Plasma Coagulation Factor XIII, Transglutaminase 3 and N epsilon-(gamma-glutamyl) lysine cross-Link in the Silicotic Nodule by Immunohistochemistry / 대한산업의학회지

OBJECTIVES: This study was performed to examine the immunohistochemical distribution of TGase 1, 2, 3, coagulation factor XIII and N epsilon-(gamma-glutamyl) lysine cross-link in the silicotic nodules formed after an intratracheal instillation of the silica. METHODS: The immunohistochemical examinations used antibodies against TGase 1, 2, 3, coagulation factor XIII and N epsilon-(gamma-glutamyl) lysine isopeptide in the silicotic nodules induced after an intratracheal instillation of 50 mg of size fractionated, crystalline silica. RESULTS: A high level of TGase 3 was related to the severity of fibrosis in silicotic nodules and extracellular coagulation factor XIII was detected around the nodules. Expressions of both membrane-bound TGase 1 and TGase 2 were barely detected in the nodules although high expressions were detected in the intact lung. Formation of N epsilon-(gamma-glutamyl) lysine cross-links was increased in severe fibrotic nodules. CONCLUSIONS: TGase 3 might contribute to the eventual stone-like fibrosis via formation of N epsilon-(gamma-glutamyl) lysine cross-links. Futhermore, coagulation factor XIII plays a role in the formation of a provisional matrix which results in fibrogenesis during silicotic nodule formation.

Antioxidant Assay of Extracted Fractions Xanthium Strumarium L Using Lens Protein Crosslink Activity

PURPOSE: To elucidate the anti-oxidant effect of extract fractions from Xanthium strumarium L. on lens protein by crosslinking assay. METHODS: [(1 4)C] N-formyl-lysine was synthesized and purified by ion exchange chromatography. The crosslinking activities of extract fractions(Xan Crude, Xan CHCl3, Xan EtAc and Xan H2O) to lens protein were determined by incorporation with [(14)C] N-formyl-lysine. RESULTS: It was observed that Xan Crude, Xan CHCl3, and Xan EtAc extracted from Xanthium strumarium L. showed approximately 10% of antioxidant effect whereas Xan H2O showed no effect by crosslinking assay. CONCLUSIONS: This study showed that the crosslinking assay described in this study can be developed as a potential tool to screen the anti-oxidant effect rapidly and accurately compared to MTT assay. The result was compared to MTT assay using Human Lens epithelial cell line.

The cross-links between outer hair cell stereocilia in the guinea pig cochlea / 解放军医学杂志

Objective To investigate the structure and function of cross-links on stereocilia of guinea pig outer hair cell (OHC). Method The ultrastructures of cross-links on stereocilia of guinea pig OHC were observed by scanning electron microscopy and tannic acid procedures. Results The side-links ran horizontally between OHC stereocilia. The stereocilia of the same and different row on each hair cell were joined by horizontally-running links. The side-links were observed in the first turn as well as the fourth turn. There were more side-links on the intact stereocilia than that on the disrupted arrangement. The side-links in the first turn and the fourth turn were more abundant than that in the second turn and the third turn. The side-links between stereocilia were spare if the stereocilia were separated. The number of side-links on stereocilia was proportional to the number of bulb-like structures on stereocilia. Conclusion The side-link is a kind of morphological structure on hair cells stereocilia of cochlea. The results suggest that cross-links play an important role in maintaining the structure and function of the hair cell stereocilia.

Chemical modification of RBC surface antigen with glutaraldehyde crosslinking / 대한수혈학회지

BACKGROUND: The chemical modification of RBC surface antigen has many advantages for safe transfusion practice. We evaluated the change of antibody reactivity to RBC surface antigen before and after glutaraldehyde crosslinking. MATERIALS AND METHODS: The 10 mL of blood were collected from 20 volunteers and were treated by 2-3% glutaraldehyde at 4degrees C. After 30 minute incubation, Agglutinability of various RBC surface antigen (ABO, Rh-C, c, D, E, e) was measured by titration using anti-sera (Green Cross, Korea, Dade, USA), and compared the agglutinability changes before and after glutaraldehyde crosslinking. RESLUTS: The agglutinability of Rh surface antigens (D, C, c, E, e) was disappeared after glutaraldehyde crosslinking. However, ABO antigens (n=20) still showed strong agglutinability against antisera with some decreased. CONCLUSIONS: It would be useful to apply glutaraldehyde crossliked RBCs for rare blood group transfusion practice, if the safety problem were solved.

DNA-Protein Crosslink Induced by Formaldehyde and Repair in Pulmonary and Renal Cells of Rats / 环境与健康杂志

Objective To explore the DNA-protein crosslink(DPC) induced by formaldehyde(FA) and the repair.Methods Three-month-old Wistar male rats were used as the experimental animals and exposed to gaseous FA at the doses of 0,0.5,1.0,3.0 mg/m3 respectively through continuous inhalation for 72 h.The cellular suspension of the lungs and kidneys was exposed to FA at the doses of 0,25,50,100,150 and 200 ?mol/L respectively for 1 h.The KCl-SDS assay was used to detect the coefficient of DPC in the lung and renal cells.The repair at 0,6,12,18 and 24 h exposure points was determined in the exposure test of 3.0 mg/m3 for 72 h in vivo and 75 ?mol/L for 1 h in vitro.Results Higher gaseous FA(≥1.0 mg/m3) could significantly cause DPC(P