Biomedical subjects

Akio Minami

Publications and source records attributed to Akio Minami.

At least 37 records · Page 2Linked to original sources

PubMed2006

Biomechanical study on the effect of five different lumbar reconstruction techniques on adjacent-level intradiscal pressure and lamina strain.

OBJECT: The objectives of this study were to compare the biomechanical effects of five lumbar reconstruction models on the adjacent segment and to analyze the effects of three factors: construct stiffness, sagittal alignment, and the number of fused segments. METHODS: Nondestructive flexion-extension tests were performed by applying pure moments to 10 calf spinal (L3-S1) specimens. One-segment (L5-6) or two-segment (L5-S1) posterior fusion methods were simulated: 1) one-segment posterolateral fusion (PLF); 2) one-segment PLF with interbody fusion cages (one-segment PLIF/PLF); 3) two-segment PLF; 4) two-segment PLIF/PLF; and 5) two-segment PLF in kyphosis (two-segment kyphotic PLF). The range of motion (ROM) of the reconstructed segments, intradiscal pressure (IDP), and lamina strain in the upper (L4-5) adjacent segment were analyzed. The ROM was significantly decreased in the PLIF/PLF models compared with that in the PLF alone models after both the one- and two-segment fusions. If the number of fused segments was increased, the pressure and strains were also increased in specimens subjected to the PLIF/PLF procedure, more so than the PLF-alone procedure. In the one-segment PLIF/PLF model the authors observed a reduced IDP and lamina strain compared with those in the kyphotic two-segment PLF model despite the latter's higher levels of initial stiffness. CONCLUSIONS: If the number of fused levels can be reduced by using PLIF to correct local kyphosis, then this procedure may be valuable for reducing adjacent-segment degenerative changes.

Animals↗

PubMed2006

Long-term follow up of surgical outcomes in patients with cervical disorders undergoing hemodialysis.

OBJECT: As increasing numbers of patients receive long-term hemodialysis, the number of reports regarding hemodialysis-related cervical spine disorders has also increased. However, there have been few reports summarizing the surgical results in patients with these disorders. The objective of this study was to evaluate the long-term follow up and clinical results after surgical treatment of cervical disorders in patients undergoing hemodialysis. METHODS: Seventeen patients in whom surgery was performed for cervical spine disorders while they received long-term hemodialysis therapy were enrolled in this study. Of these, 15 underwent follow-up review for more than 3 years after surgery, and these represent the study population. The remaining two patients died of postoperative sepsis. The average follow-up period was 120 months. Five patients without spinal instability underwent spinal cord decompression in which bilateral open-door laminoplasty was performed. Ten patients with destructive spondyloarthropathy (DSA) underwent reconstructive surgery involving pedicle screw (PS) fixation. In eight patients in whom posterior instrumentation was placed, anterior strut bone grafting was performed with autologous iliac bone to treat anterior-column destruction. Marked neurological recovery was obtained in all patients after the initial surgery. In the mobile segments adjacent to the site of previous spinal fusion, the authors observed progressive destructive changes with significant instability in four patients (40%) who underwent circumferential spinal fusion. No patients required a second surgery after laminoplasty for spinal canal stenosis without DSA changes. CONCLUSIONS: Cervical PS-assisted reconstruction provided an excellent fusion rate and good spinal alignment. During the long-term follow-up period, however, some cases required extension of the spinal fusion due to the destructive changes in the adjacent vertebral levels. Guidelines or recommendations to overcome these problems should be produced to further increase the survival rates of patients undergoing hemodialysis.

Adult↗

PubMed2006

[Surgical treatment for osteoporotic spinal fractures in the thoraco-lumbar spine].

Most of osteoporotic spinal fractures can be successfully treated with conservative treatment. In some patients, however, conservative treatment is not effective and progressive vertebral collapse with neurological problems at thoraco-lumbar spine may occur. In this chapter, surgical indication and timing in patients with osteoporotic vertebral collapse are described. Surgical options including vertebroplasty, kyphoplasty, anterior reconstruction, posterior reconstruction, and combined anterior and posterior surgery are also described. The readers can understand both advantages and disadvantages of each surgical procedure. In senile patients, preoperative general conditions including comorbid medical problems should be taken into account to determine surgical treatments. Rigid and long spinal fusion using metal implants may lead to spinal fractures at adjacent vertebral bodies to the fused segments.

Aged↗

PubMed2005

Induction of p21(WAF1/CIP1) by human synovial sarcoma-associated chimeric oncoprotein SYT-SSX1.

Oncogenic protein provokes cell cycle arrest termed premature senescence. In this process Ras has been known to induce cyclin-dependent kinase inhibitor (CKI) p16(INK4A) in primary fibroblasts. Here, we present a novel finding that human chimeric oncoprotein SYT-SSX1 induces CKI p21(WAF1/CIP1) (p21) for suppression of cell growth. In human synovial sarcoma cell lines, the expression levels of p21 were high and the transcriptional activity of the p21 gene promoter was significantly elevated. The transient expression of SYT-SSX1-induced activation of the p21 gene promoter in human diploid fibroblasts. The N-terminus deletion form of SYT-SSX1, which failed to bind to hBRM one of the chromatin remodeling factors, preserved the p21 induction ability. This effect of SYT-SSX1 was similar in extent in both wild-type and p53-deficient HCT116 cell lines. Furthermore, the introduction of mutation in Sp1/Sp3 binding sites of the p21 gene promoter abolished the SYT-SSX1-induced transcriptional activity of its promoter. In SW13 cells, the stable expression of SYT-SSX1 suppressed cell growth in culture. These results suggest that SYT-SSX1 is able to induce p21 in a manner independent on hBRM and p53 but dependent on Sp1/Sp3.

Animals↗

PubMed2005

Novel chitosan-based hyaluronan hybrid polymer fibers as a scaffold in ligament tissue engineering.

To clarify the feasibility of using novel chitosan-based hyaluronan hybrid polymer fibers as a scaffold in ligament tissue engineering, their mechanical properties and ability to promote cellular adhesion, proliferation, and extracellular matrix production were studied in vitro. Chitosan fibers and chitosan-based 0.05% and 0.1% hyaluronan hybrid fibers were developed by the wet spinning method. Hyaluronan coating significantly increased mechanical properties, compared to the chitosan fibers. Rabbit fibroblasts adhesion onto hybrid fibers was significantly greater than for the control and chitosan fibers. For analysis of cell proliferation and extracellular matrix production, a three-dimensional scaffold was created by simply piling up each fiber. At 1 day after cultivation, the DNA content in the hybrid scaffolds was higher than that in the chitosan scaffold. Scanning electron microscopy showed that the fibroblasts had produced collagen fibers after 14 days of culture. Immunostaining for type I collagen was clearly predominant in the hybrid scaffolds, and the mRNA level of type I collagen in the hybrid scaffolds were significantly greater than that in the chitosan scaffold. The present study revealed that hyaluronan hybridization with chitosan fibers enhanced fiber mechanical properties and in vitro biological effects on the cultured fibroblasts.

Animals↗

PubMed2005

Application of tissue engineering techniques for rotator cuff regeneration using a chitosan-based hyaluronan hybrid fiber scaffold.

BACKGROUND: The current surgical procedures for irreparable rotator cuff tears have considerable limitations. Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing these conditions. HYPOTHESIS: A chitosan-based hyaluronan hybrid scaffold could enhance type I collagen products with seeded fibroblasts and thereby increase the mechanical strength of regenerated tendon in vivo. STUDY DESIGN: Controlled laboratory study. METHODS: The scaffolds were created from chitosan-based hyaluronan hybrid polymer fibers. Forty-eight rabbit infraspinatus tendons and their humeral insertions were removed to create defects. Each defect was covered with a fibroblast-seeded scaffold (n = 16) or a non-fibroblast-seeded scaffold (n = 16). In the other 16 shoulders, the rotator cuff defect was left free as the control. At 4 and 12 weeks after surgery, the engineered tendons were assessed by histological, immunohistochemical (n = 2), and biomechanical (n = 6) analyses. RESULTS: Type I collagen was only seen in the fibroblast-seeded scaffold and increased in the regenerated tissue. The tensile strength and tangent modulus in the fibroblast-seeded scaffold were significantly improved from 4 to 12 weeks postoperatively. The fibroblast-seeded scaffold had a significantly greater tangent modulus than did the non-fibroblast-seeded scaffold and the control at 12 weeks. CONCLUSION: This scaffold material enhanced the production of type I collagen and led to improved mechanical strength in the regenerated tissues of the rotator cuff in vivo. CLINICAL RELEVANCE: Rotator cuff regeneration is feasible using this tissue engineering technique.

Animals↗

PubMed2005

A novel back school using a multidisciplinary team approach featuring quantitative functional evaluation and therapeutic exercises for patients with chronic low back pain: the Japanese experience in the general setting.

STUDY DESIGN: A prospective cohort study. OBJECTIVES: To introduce a novel back school for the treatment of patients with chronic low back pain (CLBP), and to report its clinical results. SUMMARY OF BACKGROUND DATA: Although back school is one of the treatment methods for patients with CLBP, its efficacy and appropriate style remain controversial. No studies have been published regarding the combined program of back school with a multidisciplinary team approach. METHODS: A total of 182 patients with CLBP (74 men and 108 women; average age, 43.8 years) participated in this study. All patients were enrolled in the back school using a multidisciplinary team approach featuring quantitative functional evaluation and therapeutic exercises. The following outcome measures were evaluated at the baseline, and 6 and 12 months after the enrollment: the level of pain evaluated with a Visual Analog Scale (VAS), flexibility of trunk and hamstrings (finger-floor distance, straight leg raising), trunk muscle strength and endurance, frequency of therapeutic exercises, and self-reported patient satisfaction. RESULTS: An averaged VAS score was 6.2 before enrollment in the program and 2.8 at follow-up. The pain improved in 141 patients (80.8%), did not change in 27 (15.4%), and was aggravated in 7 (3.8%). There was statistically significant improvement of finger-floor distance, trunk muscle strength, and endurance in the patients whose pain was relieved after enrollment in the program (P < 0.05). The compliance with the exercise program was significantly correlated with the clinical results (P < 0.05). CONCLUSIONS: We developed a novel back school using a multidisciplinary team approach, featuring quantitative functional evaluation and therapeutic exercises. The current study demonstrated that our program could provide a satisfactory result for the treatment of patients with CLBP. The quantitative functional evaluation was a worthwhile outcome measure when evaluating the efficacy of the treatment program. Teaching body mechanics and performing the therapeutic exercises through the multidisciplinary team approach are essential to managing CLBP in a general setting.

Adult↗

PubMed2005

An investigational study on the healing process of anterior spinal arthrodesis using a bioactive ceramic spacer and the change in load-sharing of spinal instrumentation.

STUDY DESIGN: Ceramic anterior lumbar interbody arthrodesis was performed using an in vivo sheep model. Observations of fusion status and the load-sharing of spinal instrumentation were studied at sequential intervals for 1 year after surgery. OBJECTIVES: To elucidate the healing process of spinal arthrodesis performed with a bioactive ceramic spacer and the change in load-sharing of anterior spinal instrumentation. SUMMARY OF BACKGROUND DATA: With the improved development of spinal instrumentation, anterior spinal arthrodesis has become a standard spinal reconstruction technique; however, the mechanistic basis underlying the healing process is not well documented. Moreover, it remains unclear how load-distribution through the fusion mass and spinal instrumentation change throughout the healing process. METHODS: Using 24 sheep, a two-level anterior lumbar interbody fusion (L2-L3, L4-L5) was performed using a smooth surface and a porous surface-modified bioactive ceramic, with each segment instrumented using a one-rod anterior spinal instrumentation system. Four animals each were killed at 2, 4, 8, 12, 24, and 52 weeks after surgery. Postmortem analysis included quantification of anterior rod strain under multidirectional flexibility testing and radiographic and histologic analyses of the arthrodesed segments. RESULTS: From 0 to 8 weeks after surgery, the bending strain of the rod gradually decreased despite no obvious bone formation. From 8 to 24 weeks after surgery, the rod strain markedly decreased with the development of bridging trabeculated bone formation between vertebral bodies. After 24 weeks after surgery, minimal changes were observed in rod strain; however, the fusion mass volumetrically increased with corresponding facet joint atrophy. The porous surface-modification of ceramic did not influence the histologic healing process, despite the improvement of interface osseous union rate. CONCLUSIONS: In anterior spinal arthrodesis, spinal instrumentation is mainly exposed to bending stress, with decreased load-sharing with corresponding development of the spinal fusion. Continuous bone remodeling of the anterior fusion mass results in concurrent decreases in spinal instrumentation and posterior spinal element load-transmission. The principal healing mechanism of ceramic anterior interbody spinal fusion is not an osseous union between the ceramic and vertebral body, but bridging bone formation around the ceramic, which directly connects the vertebral bodies above and below the disc.

Animals↗

PubMed2005

Carbohydrate analysis by a phenol-sulfuric acid method in microplate format.

Among many colorimetric methods for carbohydrate analysis, the phenol-sulfuric acid method is the easiest and most reliable method. It has been used for measuring neutral sugars in oligosaccharides, proteoglycans, glycoproteins, and glycolipids. This method is used widely because of its sensitivity and simplicity. In its original form, it required 50-450 nmol of monosaccharides or equivalent for analysis and thus is inadequate for precious samples. A scaled-down version requiring only 10-80 nmol of sugars was reported previously. We have now modified and optimized this method to use 96-well microplates for high throughput, to gain greater sensitivity, and to economize the reagents. This modified and optimized method allows longer linear range (1-150 nmol for Man) and excellent sensitivity. Moreover, our method is more convenient, requiring neither shaking nor covering, and takes less than 15 min to complete. The speed and simplicity of this method would make it most suitable for analyses of large numbers of samples such as chromatographic fractions.

Carbohydrates↗

PubMed2005

The effect of cyclic loading on the biomechanical characteristics of the femur-graft-tibia complex after anterior cruciate ligament reconstruction using Bone Mulch screw/WasherLoc fixation.

BACKGROUND: The Bone Mulch screw/WasherLoc fixation system has attracted notice because of its possible advantages. The purpose of the present study was to compare the biomechanical properties of this fixation system for the double-looped flexor tendon graft with those of two standard fixation techniques that had been commonly performed in anterior cruciate ligament reconstruction. METHODS: Anterior cruciate ligament reconstruction was carried out in each group using one of three different procedures (n=14 for each procedure). For each group, seven femur-graft-tibia complexes underwent submaximal cyclic displacement of 5000 cycles after an initial tension of 20N was applied. Then, tensile testing was performed for the complex at a single position, 45 degrees of knee flexion, in which the longitudinal axis of the graft coincided with the axis of the bone tunnels. The remaining seven complexes in each group were examined in the same tensile test without applying any cyclic displacement. FINDINGS: At the 5000th cycle of the displacement, the peak load of the complex with the Bone Mulch screw/WasherLoc system was significantly higher than that with the Endobutton technique (P<0.0001). After 5000 cycles of displacement, the initial stiffness and the linear stiffness of the complex with the Bone Mulch screw/WasherLoc system were significantly higher than those with the double-looped tendon graft and the Endobutton technique (P<0.0001 for both comparisons), while those with the Bone Mulch screw/WasherLoc system were significantly lower than those with the patellar tendon graft with interference screws (initial stiffness: P=0.0004, linear stiffness: P=0.0007). INTERPRETATION: The present study has clarified that the Bone Mulch screw/WasherLoc system provides high stiffness to the complex for the double-looped flexor tendon graft.

Animals↗

PubMed2005

Alginate and chitosan polyion complex hybrid fibers for scaffolds in ligament and tendon tissue engineering.

Selecting the material for a scaffold is critically important for the success of tissue engineering. To simplify complicated biosynthetic matrices and achieve a novel class of potential materials, a model of polyion complex fibers was prepared from alginate and chitosan. In the current in vitro study, we thought that alginate-based chitosan hybrid biomaterials could provide excellent supports for fibroblast adhesion. In the current study, alginate polymer fiber (alginate group) and alginate-based chitosan hybrid polymer fibers (alginate with 0.05% chitosan, alginate-chitosan 0.05% group; alginate with 0.1% chitosan, alginate-chitosan 0.1% group) were originally prepared. We investigated the adhesion behavior of rabbit tendon fibroblast onto alginate polymer fibers versus the adhesion of the fibroblast onto alginate-based chitosan hybrid polymer fibers. Furthermore, mechanical properties and synthesis of the extracellular matrix were investigated. Mechanically, the novel fiber has considerable tensile strength of more than 200 MPa. We demonstrated that the alginate-based chitosan hybrid polymer fibers showed much improved adhesion capacity with fibroblast compared with alginate polymer fiber. Additionally, morphologic studies revealed the dense fiber of the type I collagen produced by the fibroblast in the hybrid polymer fibers. We concluded that an alginate-based chitosan hybrid polymer fiber has considerable potential as a desirable biomaterial scaffold for tendon and ligament tissue engineering.

Alginates↗

PubMed2005

Transtrochanteric rotational osteotomy for osteonecrosis of the femoral head: relation between radiographic features and secondary collapse.

BACKGROUND: Secondary collapse of the femoral head after transtrochanteric rotational osteotomy (TRO) for osteonecrosis of the femoral head is a major complication leading to failure. We investigated the relation between the extent and shape of a newly established healthy weight-bearing area and the incidence of secondary collapse. METHODS: Altogether, 38 hips in 32 patients with a mean age of 33 years at the time of surgery were followed for a mean of 4 years. RESULTS: The outcome was satisfactory in 22 hips (58%) and unsatisfactory in 16 hips (42%), with 9 requiring total hip arthroplasty. The extent of the newly established healthy weight-bearing area as depicted on the immediate postoperative radiograph was significantly greater in the satisfactory group than in the unsatisfactory group. The rate of secondary collapse was significantly higher when the newly established weight-bearing area was thin, like a beak ("beak-shaped" healthy area). The incidence of a beak-shaped healthy area was significantly higher in the steroid group than in nonsteroid group. CONCLUSIONS: We concluded that we should be cautious when the newly established healthy weight-bearing area exhibits this beak shape, even if its extent in the weight-bearing area is large, because of the higher risk of postoperative secondary collapse. In such cases, alteration of the after-treatment program (e.g., prolonging the non-weight-bearing period) should be considered.

Adolescent↗

PubMed2005

The effect of electrothermal shrinkage on the biomechanical properties of the anterior cruciate ligament: an experimental study.

PURPOSE: The purpose of this study was to determine the acute effects of electrothermal shrinkage on the biomechanical properties of the anterior cruciate ligament (ACL). TYPE OF STUDY: Randomized trial. METHODS: Fifty fresh femur-ACL-tibia complexes harvested from fully matured pigs were used. The femur-anteromedial bundle-tibia complex specimens were randomly divided into 5 groups of 10 specimens each. In each group, radiofrequency energy set at nonablative levels was applied to the anteromedial bundle of the ACL with a bipolar radiofrequency generator. In groups I and II, radiofrequency treatment was applied to the ACL using 28 W and 45 W power, respectively, for 30 seconds. In groups III and IV, radiofrequency treatment was applied to the ACL using 28 W and 45 W power, respectively, for 60 seconds. In group V, no treatment was applied in order to obtain normal control data. The treatment was performed in physiological saline solution under a 1-N load. In each group, 8 of the 10 specimens were used for biomechanical evaluation, and the remaining 2 were used for histologic observation. RESULTS: Concerning the length of the anteromedial bundle after the treatment, the analysis of variance (ANOVA) showed a significant difference among the 5 groups. The length in groups I, II, III, and IV was significantly shorter than that of group V. In tensile testing, the stiffness was 120, 116, 113, 89, and 156 N/mm in groups I, II, III, IV, and V, respectively. The ANOVA showed a significant difference among the groups. Groups I, II, III, and IV were significantly lower than group V, respectively. Histologic examination showed diffuse collagenous denaturation and pyknotic nuclear changes in fibroblasts at the treated portion. The collagen crimp pattern was not present in the treated area. CONCLUSIONS: Application of RF energy to the specimens caused both shortening and weakening according to the magnitude and duration of the application. CLINICAL RELEVANCE: These results may explain one of the causes of the poor results reported in some clinical studies. This study warns against a too optimistic application of electrothermal shrinkage to the ACL as a clinical treatment.

Animals↗

PubMed2005

The effect of transforming growth factor-beta1 on intraosseous healing of flexor tendon autograft replacement of anterior cruciate ligament in dogs.

PURPOSE: To clarify the effect of transforming growth factor (TGF)-beta1 on intraosseous healing of the flexor tendon autograft in anterior cruciate ligament (ACL) replacement. TYPE OF STUDY: Randomized trial in animals. METHODS: Twenty-one adult beagle dogs were divided into 3 groups of 7 animals each. The ACL was replaced with a flexor tendon autograft in the left knee. The distal end of each graft was placed in the tibial bone tunnel. In group I, no treatment was applied in the bone tunnel. In group II, 0.1 mL of fibrin sealant was applied in the tendon-bone gap. In group III, 2 ng of TGF-beta1 mixed with 0.1 mL fibrin sealant was applied in the gap. Each animal was euthanized 3 weeks after surgery. RESULTS: In pullout testing, the ultimate load of the graft-tibia complex of group III (188.2 +/- 51.4 N) was significantly greater than that of groups I (86.7 +/- 36.5 N) and II (99.0 +/- 18.7 N) (P = .005). There were no significant differences between groups I and II. Histologically, the perpendicular collagen fibers connecting the tendon to the bone were narrowly seen in groups I and II, whereas the fibers were richly generated in group III. CONCLUSIONS: In ACL replacement using flexor tendon autograft, exogenous administration of TGF-beta1 significantly increased the bonding strength of the graft to the tunnel wall at 3 weeks, although the long-term effects are unknown. CLINICAL RELEVANCE: Intraosseous healing of the flexor tendon autograft in ACL reconstruction may be enhanced by a use of some growth factors involving TGF-beta1 in the future.

Animals↗

PubMed2005

Feasibility of chitosan-based hyaluronic acid hybrid biomaterial for a novel scaffold in cartilage tissue engineering.

In this study, we hypothesized that hyaluronic acid could provide superior biological effects on the chondrocytes in a three-dimensional culture system. To test this hypothesis, we investigated the in vitro behavior of rabbit chondrocytes on a novel chitosan-based hyaluronic acid hybrid polymer fiber. The goal of the current study was to show the superiority of this novel fiber as a scaffold biomaterial for cartilage tissue engineering. Chitosan polymer fibers (chitosan group) and chitosan-based hyaluronic acid hybrid polymer fibers (HA 0.04% and HA 0.07% groups, chitosan coated with hyaluronic acid 0.04% and 0.07%, respectively) were originally developed by the wetspinning method. Articular chondrocytes were isolated from Japanese white rabbits and cultured in the sheets consisting of each polymer fiber. The effects of each polymer fiber on cell adhesivity, proliferation, morphological changes, and synthesis of the extracellular matrix were analyzed by quantitative a cell attachment test, DNA quantification, light and scanning electron microscopy, semi-quantitative RT-PCR, and immunohistochemical analysis. Cell adhesivity, proliferation and the synthesis of aggrecan were significantly higher in the hybrid fiber (HA 0.04% and 0.07%) groups than in the chitosan group. On the cultured hybrid polymer materials, scanning electron microscopic observation showed that chondrocytes proliferated while maintaining their morphological phenotype and with a rich extracellular matrix synthesis around the cells. Immunohistochemical staining with an anti-type II collagen antibody demonstrated rich production of the type II collagen in the pericellular matrix from the chondrocytes. The chitosan-based hyaluronic acid hybrid polymer fibers show great potential as a desirable biomaterial for cartilaginous tissue scaffolds.

Animals↗

PubMed2005

A biomechanical and histological evaluation of a bioresorbable lumbar interbody fusion cage.

Novel spinal interbody fusion cages made of bioactive and bioresorbable composites by a unique forging process were developed. Previous in vitro study demonstrated that these cages marked excellent biomechanical values. The purpose of the present in vivo study was to evaluate the viability and advantage of this forged composite of uncalcined hydroxyapatite/poly L-Lactide (F-u-HA/PLLA) cage radiographically, biomechanically, and histologically, when compared to conventional autologous iliac bone (AIB) and carbon fiber cage (CFC). Twenty-five mature sheep underwent posterior lumbar interbody fusion at L2-3 level with pedicle screws system made of titanium. Three types of interbody fusion implants were grafted: AIB (n = 7), CFCs (n = 9), F-u-HA/PLLA cages (n = 9). Two types of cages were packed with autologous fragmented cancellous bone harvested locally. All animals were euthanized at 120 days after surgery. The fusion scoring using the coronal view CT scans was designed to three-dimensionally evaluate fusion quality within and around cages. The mean CT scores of three groups were 33.3 points, 35.0 points, and 33.6 points in AIB, CFC, and F-u-HA/PLLA cage groups, respectively (full-score: 56 points). Statistical differences were not detected among the three groups. The mean range of motion values among fused groups had no significant difference under all pure loadings. The range of motion showed strong and significant correlation with the CT fusion scores. Histologic results demonstrated that F-u-HA/PLLA cages contacted with the surrounding bone directly, and CFC was encircled with thick fibrous tissue layers without any sign of inflammation around cages. The fusion quality of fused spinal segment using F-u-HA/PLLA cages was equal to that of AIB or CFCs both radiographically and biomechanically. In the histological observation, biocompatibility of F-u-HA/PLLA cage was obviously superior to CFC. It has been confirmed that the novel bioactive and bioresorbable cages had valuable advantages over existing CFC for use in spinal reconstructive surgery.

Absorbable Implants↗

PubMed2005

Chitosan-RGDSGGC conjugate as a scaffold material for musculoskeletal tissue engineering.

In the present study, we have developed a novel and versatile method for the preparation of chitosan-peptide complex based on the selective reaction of chitosan with 2-iminothiolane. The new type of SH-chitosan derivative showed an excellent solubility to aqueous solution even in the alkaline conditions. This characteristic greatly facilitated further modification study of chitosan with a variety of bioactive substances. A synthetic peptide, RGDSGGC containing RGDS moiety that is known as one of the most important cell adhesive peptides, was readily coupled by disulfide bonds formation with sulfhydryl groups of SH-chitosan in the presence of dimethyl sulfoxide. Next, the effect of the introduction of RGDSGGC moiety to chitosan on cell adhesion and proliferation activity of chondrocytes and fibroblasts were evaluated. As a result, it was suggested that this polysaccharide-peptide conjugate exhibited excellent capacities for both cell adhesion and cell proliferation of chondrocytes and fibroblasts. Considering the growing importance of the biocompatible scaffolds in the recent tailored tissue engineering technique, these results indicate that the present strategy of 2-iminothiolane-based conjugation of polysaccharides with biologically active peptides will become a key and potential technology to develop desirable scaffold materials for the tissue regenerations.

Adsorption↗

PubMed2005

The effect of transforming growth factor-beta on mechanical properties of the fibrous tissue regenerated in the patellar tendon after resecting the central portion.

BACKGROUND: No investigators have studied the effects of an application of growth factors on the in vivo tissue regeneration in the tendon after resecting the central portion. The purpose of this study is to clarify whether an application of transforming growth factor (TGF)-beta1 increases the mechanical properties of the regenerated tissue in the patellar tendon after resecting the central portion. METHODS: Thirty female rabbits were divided into three groups, after a 3 mm wide and 10 mm long tendon substance was resected from the central portion in the patellar tendon. In Group I, 5-ng TGF-beta1 dissolved in 0.1-ml saline was injected into the resected portion in the patellar tendon. In Group II, only 0.1-ml saline was injected into the resected portion. In Group III, nothing was injected. All animals were sacrificed at 6 weeks after surgery. Mechanical and histological evaluations were made concerning the regenerated tissue and the unresected tendon tissue in the patellar tendon. FINDINGS: Concerning the regenerated tissue, the tangent modulus and the tensile strength of Group I were significantly greater than those of Groups II and III, while there were no significant differences in these parameters between Groups II and III. INTERPRETATION: The application of TGF-beta1 significantly increases the tangent modulus and the tensile strength of the fibrous tissue regenerated in the patellar tendon after resecting the central portion. This study has provided basic important information on the utility of TGF-beta1 in the in vivo tendon regeneration.

Adaptation, Physiological↗