Biomedical subjects

Ryosuke Kuroda

Publications and source records attributed to Ryosuke Kuroda.

31 records · Page 2Linked to original sources

PubMed2004

Revision anterior cruciate ligament reconstruction using the regenerated semitendinosus tendon: analysis of ultrastructure of the regenerated tendon.

In this report, we present a case of a college skier who sustained a rerupture of the reconstructed anterior cruciate ligament (ACL) 8 months after surgery in which an autogenous semitendinosus tendon graft was used. At the revision surgery, the harvested semitendinosus tendon appeared to be regrown. Thus the regenerated tendon was reharvested, and in combination with the gracilis tendon, was used as a graft. The electron microscopic examination revealed a difference in fibril diameter between the regenerated tissue and the normal tendon. Although the regenerated semitendinosus tendon could be reharvested, the feasibility of its use for revision surgery is still to be determined.

Adult↗

PubMed2004

Expression of transcription factor Sox9 in rat L6 myoblastic cells.

Muscle-derived cells can differentiate into chondrogenic cells. In our present study, we investigated the pattern of expression of Sox9, a transcription factor known to play a key role in chondrogenesis, in a rat myoblastic cell line, L6. In addition, we evaluated expression of type II collagen and myogenic regulatory markers by reverse-transcript polymerase chain reaction. We also investigated the effect of transforming growth factor (TGF)-beta3, which is known to induce chondrogenesis, on Sox9 mRNA expression. On the first day of culture, we observed a high expression of Sox9. However, on the seventh day of culture, there was a decline in the level of Sox9 and type II collagen mRNAs and an increased expression of Myf5 and myogenin mRNAs. Sox9 mRNA expression was increased after stimulation of TGF-beta3 at 2, 6, and 24 hr. Cartilage nodules were observed in L6 cells treated with TGF-beta3 and dexamethasone. These results indicated that L6 myoblasts originally possess the capacity to differentiate into chondrogenic cells, but that capacity is lost as the cells differentiate toward the myogenic lineage. In addition, TGF-beta3 may modulate Sox9 mRNA expression in L6 cells and retain the capacity to differentiate into chondrogenic lineage.

Animals↗

PubMed2003

The role of cell type in bone healing mediated by ex vivo gene therapy.

BACKGROUND: The ideal cellular vehicle for use in cell-mediated gene therapy to enhance bone healing has not yet been identified. The purpose of this study was to compare the capacity of two types of cells transduced with retro-bone morphogenetic protein 4 (BMP4)-muscle-derived cells (MDCs) and unfractioned bone marrow stromal cells (BMSCs). METHOD: Primary rat MDCs and unfractioned rat BMSCs were transduced with a retrovirus to express BMP4. A 7-mm, critical-sized femur defect was created in adult rats, and 5 x 10(6) transduced cells were implanted into the femoral defect. Bone healing was monitored radiographically and histologically at 4, 8, and 12 weeks post-implantation. RESULTS: All specimens in the MDC-BMP4 group and BMSC-BMP4 group showed a bridging callus at 8 and 12 weeks. At 12 weeks post-implantation the calluses of the MDC-BMP4 femora displayed significantly higher bone photodensity than the BMSC-BMP4 femora (P<0.05). Histomorphometry revealed no difference between the two treatment groups. However, non-union between newly formed and original bone was observed in none of the MDC femora but in six femora from the BMSC-BMP4 group. CONCLUSION: Both MDCs and unfractioned BMSCs can improve healing of a critical-sized bone defect following transduction of the cells with retroBMP4. However, MDCs appear to yield superior results when compared with BMSCs in terms of improved healing of segmental defects.

Animals↗

PubMed2003

Gene therapy to improve osteogenesis in bone lesions with severe soft tissue damage.

BACKGROUND: Ex vivo gene therapy can induce bone formation when delivery cells carrying the bone morphogenetic protein (BMP) gene are used. The hypothesis for this study was that the cell-mediated gene therapy could improve the healing of bony lesions with severe soft tissue damage. METHOD: An animal model with a femoral osteotomy lesion associated with soft tissue damage was developed in rats. Muscle-derived cells, genetically engineered to express BMP4, were inserted within the osteotomy gap. Cells genetically engineered to express LacZ were used for the control group. The groups were subdivided with regard to the fixation method: stable and unstable fixation. The rats were killed for histological and radiographic evaluation 3 and 6 weeks post-surgery. RESULTS: No callus formation was found in the control group at any time point, whereas sufficient callus formation appeared in the treatment group after 6 weeks. A bridging callus with woven bone and hypertrophic chondrocytes was achieved in the treatment group when a stable fixation was used, but failed to appear in unstable fixation. CONCLUSION: The combination of muscle-derived cells expressing BMP4 and a stable fixation were able to bridge the bone defect within 6 weeks, but with prolonged osteochondral ossification. Therefore, the ex vivo gene therapy could be an efficient biological approach to improve the treatment of bone lesions with severe soft tissue damage.

Animals↗

PubMed2003

Avulsion fracture of the posterior oblique ligament associated with acute tear of the medial collateral ligament.

The term posterior oblique ligament was proposed in 1973 but the specific anatomy of this region has been controversial. It has been concluded that the posterior oblique ligament is separated from the medial collateral ligament, each with distinctly different bony attachment points. In this article, we report a posterior oblique ligament avulsion fracture associated with a medial collateral ligament rupture.

Accidents, Traffic↗

PubMed2003

Cross-sectional area of a bone-patellar tendon-bone graft for anterior cruciate ligament reconstruction.

The cross-sectional area of the 10-mm wide patellar tendon graft was measured in 50 consecutive patients (31 males and 19 females) who underwent isolated anterior cruciate ligament (ACL) reconstruction and the relationship between the graft size and various factors such as physical characteristics was assessed. The effect of cross-sectional area of the implanted graft on postoperative stability of the reconstructed knee also was examined. Mean patient age at surgery was 22.3 years (range: 14-40 years). The cross-sectional area was measured using an instrumented area micrometer intraoperatively, and correlations between the measured value and various factors such as age, gender, height, body weight, and bony geometry were examined. Follow-up was performed 24 months postoperatively. The average cross-sectional graft area was 33.4 mm2. The measured cross-sectional area was larger in male patients and correlated with physical characteristics such as height, body weight, and femoral condyle width. No significant correlation between the size of the graft and postoperative stability was observed.

Adolescent↗

PubMed2002

Insulin growth factor-1 decreases muscle atrophy following denervation.

Despite modern microsurgical techniques for nerve repair, functional outcome following proximal injury is often unsatisfactory because irreversible muscle atrophy may develop before reinnervation occurs. Because insulin growth factor-1 (IGF-1) has been shown to improve muscle regeneration after injury, and may have a role in muscle preservation following denervation, the purpose of this investigation was to evaluate the histological, immunohistochemical, and electrophysiological differences between normal, denervated, and IGF-1-injected denervated muscle over an 8-week period. Denervated mice gastrocnemius muscles demonstrated a decrease in muscle weight, a decrease in myofiber diameter, an absence of muscle regeneration, an early increase in the number of neuromuscular junctions (NMJs), and a decrease in fast-twitch and maximum tetanic strength as compared to normal muscle up to 8 weeks following denervation. IGF-1-injected denervated muscle, on the other hand, sustained muscle diameter and muscle weight, maintained a smaller number of NMJs, and relatively sustained fast-twitch and maximum tetanic strength as compared to normal muscle over 8 weeks. These data suggest that IGF-1 may help prevent muscle atrophy and secondary functional compromise after denervation.

Animals↗

PubMed2002

Graft tension and knee stability after anterior cruciate ligament reconstruction.

This study examined the effect of the initial graft tension on the clinical outcome of anterior cruciate ligament reconstruction in a prospective randomized design. Fifty patients were enrolled in the study. In the reconstructive procedure, a bone-patellar tendon-bone graft was used. A set force of 25 N (5.6 lb) was applied in 25 patients and 50 N (11.2 lb) tension was maintained during fixation for the remaining 25 patients with the knee in full extension. In the immediate postoperative period, the anterior cruciate ligament reconstructed knee was similarly overconstrained in both groups. At 3 months, laxity of the surgically treated knee in both groups had increased significantly and become close to that of the contralateral knee. Measured laxity value showed a slight increase between 3 and 6 months, and remained similar thereafter. No significant difference in the clinical outcome was observed between the groups throughout the followup.

Adolescent↗

PubMed2002

Repeat tears of repaired menisci after arthroscopic confirmation of healing.

We undertook 114 arthroscopic meniscal repairs in 111 patients and subsequently carried out second-look arthroscopy to confirm meniscal healing at a mean of 13 months after repair. Stable healing at the repaired site was seen in 90. Of these, however, 13 had another arthroscopy later for a further tear. The mean period between the repair and the observation of a repeat tear was 48 months. Of the 13 patients, 11 had returned to high activity levels (International Knee Documentation Committee level I or II) after the repair. An attempt should be made to preserve meniscal function by repairing tears, but even after arthroscopic confirmation of stable healing repaired menisci may tear again. The long-term rate of healing may not be as high as is currently reported. Second-look arthroscopy cannot predict late meniscal failure and may not be justified as a method of assessment for meniscal healing. Young patients engaged in arduous sporting activities should be reviewed regularly even after arthroscopic confirmation of healing.

Adolescent↗

PubMed2001

Distribution of patellofemoral joint pressures after femoral trochlear osteotomy.

Anterior osteotomy of the lateral femoral condyle was designed for the treatment of recurrent patellar dislocations. This study examined whether anterior femoral trochlear osteotomy significantly elevates contact pressures in the patellofemoral joint. Static intrajoint loads and contact area determination were recorded using prescale Fuji pressure-sensitive film under static loading. Peak pressures, average pressures and contact areas of the patellofemoral joint were calculated on intact specimens and after anterior osteotomy of the lateral condyle. Our results indicate that a 6-mm or 10-mm anterior osteotomy of the lateral condyle significantly elevates patellofemoral contact pressures.

Adult↗

PubMed2001

Evaluation of healing of the injured posterior cruciate ligament: Analysis of instability and magnetic resonance imaging.

PURPOSE: Knees with an acute posterior cruciate ligament (PCL) injury and soft endpoint on posterior drawer test often develop less instability and a firm endpoint at later follow-up. This type of healing is rarely seen in the acutely injured anterior cruciate ligament (ACL) and seems to be a unique feature of healing for PCL injury. The purpose of this study was to explore the healing process of the injured PCL by means of instability measurement and magnetic resonance imaging (MRI). Type of study: Consecutive sample. METHODS: Forty-eight acute PCL deficient knees were followed up and evaluated. We evaluated the detection of a so-called firm endpoint using a posterior drawer test. We also determined the degree of posterior sag and categorized them as 3 grades. Quantitative assessment of total anteroposterior (AP) translation of the tibia with a KT-1000 knee arthrometer (MedMetric, San Diego, California) was performed by manual maximum AP drawer test with the knee flexed 70 degrees. The continuity of the PCL was evaluated with sagittal and coronal T1- and T2-weighted MRIs. RESULTS: Thirty-three (69%) cases exhibited a so-called firm endpoint with a posterior drawer test. These cases showed statistically less total AP translation (mean, 7.0 mm) in KT-1000 evaluation, compared with 15 cases without an endpoint (mean, 11.9 mm). In addition, 36 cases (75%) with continuous low-intensity MRI showed statistically less AP translation (mean 7.6 mm), compared with 12 cases (mean 11.4 mm) with disrupted PCL image. CONCLUSIONS: These results suggest that a high percentage of acutely injured PCLs are likely to develop somewhat slack but continuous ligament-like tissue, and this continuous PCL-like tissue might function as a posterior restraint of the tibia to certain extent. The elongated but continuous PCL might partly explain the relatively favorable prognosis of this injury.

Journal Article↗

PubMedDate not supplied

Evaluation of hamstring strength and tendon regrowth after harvesting for anterior cruciate ligament reconstruction.

BACKGROUND: It is generally thought that tissue regeneration and good functional recovery can be expected after anterior cruciate ligament reconstruction using the hamstring tendons. However, persistent strength deficit in deep knee flexion has also been reported. HYPOTHESIS: Morphologic regeneration of the harvested hamstring tendon is not necessarily associated with its functional recovery. STUDY DESIGN: Retrospective follow-up study. METHOD: Twenty-eight patients who underwent anterior cruciate ligament reconstruction with hamstring graft were evaluated after a minimum period of 2 years. Status of tendon regrowth was assessed by magnetic resonance imaging. To specifically analyze the functional deficit after graft harvest, the isometric hamstring strength was examined in a sitting position at 90 degrees of flexion and a prone position at 90 degrees and 110 degrees of flexion. Then, the strength data were correlated with the extent of tendon regeneration. RESULTS: In 22 of the 28 patients, a regrowth of the semitendinosus tendon was found, whereas regeneration of the gracilis tendon was observed in 13 patients. In the evaluation of hamstring strength, the isometric peak torque was reduced to 86.2%, 54.6%, and 49.1%, respectively, in the aforementioned 3 postures as compared with the contralateral side. CONCLUSIONS: Significant functional deficit of hamstring strength remains regardless of morphologic regeneration.

Adolescent↗

PubMedDate not supplied

Expression of VEGF and its receptors and angiogenesis in bone and soft tissue tumors.

BACKGROUND: Tumor angiogenesis and vascularization are essential requirements for the growth and metastasis of tumors. There is evidence that overexpression of the vascular endothelial growth factor (VEGF) is correlated with an adverse prognosis in some tumors. The expression of VEGF, its receptors and microvessel density (MVD) of bone and soft tissue tumors was evaluated. MATERIALS AND METHODS: Tissue specimens of 60 patients including 30 malignant and 30 benign tumors confirmed by biopsy were examined. Expression of VEGF and its receptors (flt-1 and KDR/flk-1) was observed by immunohistochemistry. Tumor angiogenesis was assessed morphologically by measuring intratumoral MVD. RESULTS: Semi-quantitative evaluation of immunoreactivity showed that VEGF was significantly higher in malignant tumors than in benign tumors. A correlation was found between the immunoreactivity of VEGF and KDR. Moreover, correlations were found either between MVD and VEGF or between MVD and KDR/flk-1. CONCLUSION: Signal transduction, in particular by VEGF and KDR, potentially contributes to the angiogenesis of bone and soft tissue tumor.

Bone Neoplasms↗