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Biomedical subjects

Masahiro Kurosaka

Publications and source records attributed to Masahiro Kurosaka.

At least 19 recordsLinked to original sources
PubMed2007

In vitro multipotentiality and characterization of human unfractured traumatic hemarthrosis-derived progenitor cells: A potential cell source for tissue repair.

Mesenchymal progenitor cells (MPCs) are a very attractive tool in the context of repair and regeneration of musculoskeletal tissue damaged by trauma. The most common source of MPCs to date has been the bone marrow, but aspirating bone marrow from the patient is an invasive procedure. In an attempt to search for alternative sources of MPCs that could be obtained with minimal invasion, we looked into traumatic hemarthrosis of the knee. In this study, we determined whether a population of multipotent MPCs could be isolated from acute traumatic knee hemarthrosis in the absence of intra-articular fractures. Mononuclear cells were isolated from the aspirated hemarthrosis by density gradient separation, and cultured. We were able to obtain plastic adherent fibroblast-like cells from the mononuclear cell fractions. Flow cytometry analysis revealed that the adherent fibroblast-like cells were consistently positive for CD29, CD44, CD105, and CD166, and were negative for CD14, CD34, and CD45. These were similar to control bone marrow stromal cells. These cells could differentiate in vitro into osteogenic, adipogenic, and chondrogenic cells in the presence of lineage-specific induction factors. In conclusion, acute unfractured traumatic hemarthrosis of the knee contains MPCs with multipotentiality. Because knee hemarthrosis is easy to harvest with minimal pain and without unnecessary invasion, we regard hemarthrosis-derived cells as an additional progenitor cell source for future tissue engineering and cell-based therapy in knee injuries.

Adolescent↗
PubMed2007

Reliability and usefulness of a new in vivo measurement system of the pivot shift.

Residual pivot shift after ACL reconstruction is a crucial factor related to poor clinical outcome. However, no method exists that is able to evaluate pivot shift quantitatively and noninvasively. We propose a new measurement system for the pivot shift test using an electromagnetic device and have evaluated its reliability and clinical usefulness. Posterior translation, lateral translation and maximum velocity during the reduction phase of pivot shift were calculated and used as parameters for evaluation. In measurement system analysis, discrepancies of motion between the bones and the sensors were minimal, while reproducibility in repeated measurement was acceptable. Next, clinical usefulness was evaluated by correlating the values obtained by kinematic measurement with the clinical grade. We found differences in each of the measured parameters among clinical grades. These data suggest the system is a valuable measurement tool for clinical evaluation of the pivot shift test.

Anterior Cruciate Ligament↗
PubMed2007

Double-bundle ACL reconstruction can improve rotational stability.

Double-bundle anterior cruciate ligament (ACL) reconstruction reproduces anteromedial and posterolateral bundles, and thus has theoretical advantages over conventional single-bundle reconstruction in controlling rotational torque in vitro. However, its superiority in clinical practice has not been proven. We analyzed rotational stability with three reconstruction techniques in 60 consecutive patients who were randomly divided into three groups (double-bundle, anteromedial single-bundle, posterolateral single-bundle). In the reconstructive procedure, the hamstring tendon was harvested and used as a free tendon graft. Followup examinations were performed 1 year after surgery. Anteroposterior laxity of the knee was examined with a KT-1000 arthrometer, whereas rotatory instability, as elicited by the pivot shift test, was assessed using a new measurement system incorporating three-dimensional electromagnetic sensors. Routine clinical evaluations, including KT examination, demonstrated no differences among the three groups. However, using the new measurement system, patients with double-bundle ACL reconstruction showed better pivot shift control of complex instability than patients with anteromedial and posterolateral single-bundle reconstruction.

Adolescent↗
PubMed2006

The effect of graft tensioning in anatomic 2-bundle ACL reconstruction on knee joint kinematics.

Recently, double bundle ACL reconstruction, in which the two bundles thought to have different effects on knee kinematics are reconstructed separately, is widely believed to more favorably restore normal knee kinematics than conventional single bundle ACL reconstruction. However, rotational kinematics during physiological movement after double bundle reconstruction has rarely been tested. The purpose of this study was to measure the kinematics of the ACL deficient and reconstructed knees using two different tensioning conditions in double bundle reconstruction, and to examine the effects of each graft on knee kinematics. Six cadaveric knees were used. Six degrees-of-freedom of knee kinematics and the tension of each graft were monitored during simulated knee extension with the ACL intact, resected, and reconstructed under two different tensioning conditions: 50 N on anteromedial bundle and 0 N on posterolateral bundle (AM-favored condition); 0 N on anteromedial bundle and 50 N on posterolateral bundle (PL-favored condition). Tibial translation: After ACL reconstruction, the tibia overcorrected posteriorly in both conditions. Such an overcorrection in the AM-favored condition was larger than in the PL-favored condition. Tibial rotation: The tibia was significantly externally rotated after ACL reconstruction at a low flexion angle in both conditions. However, at a high flexion angle, tibial external rotation was shown only in the AM-favored condition. Graft tension: While total tensions were similar between the two conditions, the AM bundle shared more tension in the AM-favored condition than in the PL-favored condition. A total of 50 N of tension force was assumed to be excessive for normalizing knee kinematics at a low flexion angle even if double bundle reconstruction was used. Additionally, the AM-favored tensioning reconstruction made the tibia rotate externally and translate posteriorly even at a high flexion angle. Further research is needed to normalize knee kinematics after ACL reconstruction, however it is recommended that a moderate tensioning force is applied to the PL bundle and a minimal tensioning force to the AM bundle in double bundle reconstruction to obtain better knee kinematics.

Aged↗
PubMed2006

Kinetic analysis of the cervical spinal cord in patients after spinous process-splitting laminoplasty using a kinematic magnetic resonance imaging technique.

STUDY DESIGN: An in vivo flexion-extension magnetic resonance imaging study. OBJECTIVE: To evaluate the kinetic changes of the cervical spinal cord after laminoplasty in patients with cervical myelopathy. SUMMARY OF BACKGROUND DATA: Laminoplasty for cervical myelopathy increases the space occupied by the spinal cord, leading to a decompressive effect on the cord. However, there are few reports on kinetic changes of the spinal cord following this surgical procedure, by which it may contribute to an improvement of clinical symptoms. METHODS: Patients who underwent spinous process-splitting laminoplasty (n = 40) and control group (n = 20) were enrolled in the study. Cervical spines of the subjects were examined from maximum extension to maximum flexion using a magnetic resonance imaging scanner. Sagittal T1-weighted images were obtained at 12 different angle positions. Images were analyzed with respect to the distance and alignment disparity between the dorsal edge of the vertebral column and the center of the cord at each disc level using National Institutes of Health Image software. RESULTS: Spinal cords of patients after laminoplasty were dorsally shifted in the enlarged spinal canal at neutral, extension, and flexion positions. Alignment changes of the cord during flexion-extension movements of the cervical spine were dissociated from those of the vertebral column because of smaller changes in the cord alignment. CONCLUSIONS: Spinous process-splitting laminoplasty increases the degree of freedom of the spinal cord.

Aged↗
PubMed2006

The influence of proprioceptive impairment on hand function in patients with cervical myelopathy.

STUDY DESIGN: A prospective clinical study. OBJECTIVES: To quantitatively evaluate hand function in patients with cervical myelopathy and to assess the influence of proprioceptive impairment on hand function in patients with cervical myelopathy. SUMMARY OF BACKGROUND DATA: Clumsiness of the hands is one of the most common complaints in patients with cervical myelopathy. However, few reports have been published that evaluate hand dysfunction, and no reports have assessed the association between hand function and proprioceptive impairment. PATIENTS AND METHODS: A total of 129 patients (36 women and 93 men) with cervical myelopathy were examined. Hand function was evaluated as scores of ten subtests designed on the basis of various hand activities. The degree of proprioceptive impairment of the hand as well as that of light touch sensation loss is classified into four grades. Scores of the hand function test are compared according to the grade of proprioceptive impairment of the hands. RESULTS: Significant relation between the impairment of hand function and the extent of cervical myelopathy was observed. There was good correlation between the hand function scores and the grade of impairment of proprioception and light touch sensation. Furthermore, patients with impairment of proprioception obtained significantly lower scores in the hand function test than those with loss of light touch sensation. CONCLUSIONS: The hand function test is a useful battery to objectively and quantitatively evaluate impairment of cervical myelopathy, although longitudinal studies are needed to determine its practical usability. There was some relation between scores of hand function test and the extent of proprioceptive impairment. Thus, hand function test may be partly influenced by proprioceptive loss.

Adult↗
PubMed2006

Sustained transgene expression in intervertebral disc cells in vivo mediated by microbubble-enhanced ultrasound gene therapy.

STUDY DESIGN: In vivo studies using a rat model were performed to determine the feasibility of microbubble-enhanced ultrasound gene transfer technique to the intervertebral disc. OBJECTIVES: 1) To establish this microbubble-enhanced ultrasound gene therapy technique for intervertebral disc cells in vivo without using viral vectors and 2) to estimate the duration of transgene expression in vivo. SUMMARY OF BACKGROUND DATA: Intervertebral disc degeneration and associated spinal disorders remain a formidable problem. Although gene therapy approaches have been reported as having promising therapeutic potential to regenerate the disc, concerns over safety issues using recombinant viral vectors limits its application. Successful gene transfer using ultrasound has been reported in muscle and cardiovascular systems in vivo. MATERIALS AND METHODS: Two different reporter plasmid DNA encoding green fluorescent protein (GFP) and firefly luciferase were used. Plasmid DNA was mixed with ultrasonography contrast agent (microbubbles) and injected into coccygeal intervertebral discs of Sprague-Dawley rats. The therapeutic ultrasound was irradiated on the surface of injected discs. Rats were killed 1, 3, 6, 12, and 24 weeks after gene transduction. Harvested nucleus pulposus tissues were used for evaluation of transgene expression. The intact discs were used as a control. RESULTS: Seven days after gene transfection, considerable numbers of GFP-positive cells were observed in nucleus pulposus from the GFP-transfected group. Luciferase assay revealed that the ultrasound group demonstrated approximately an 11-fold increase in luciferase activity over the plasmid DNA-only group. Furthermore, transgene expression mediated by this method was observed, at least up to 24 weeks. CONCLUSIONS: Our study indicated that ultrasound transfection method with microbubbles significantly enhanced transfection efficiency of plasmid DNA into the nucleus pulposus cells in vivo. Furthermore, the sustained transgene expression in vivo was possible up to 24 weeks. The long-term gene expression mediated by simple and safe procedure has important clinical applications, including the treatment of chronic types of disease such as degenerative disc diseases.

Animals↗
PubMed2006

Rapid chondrolysis after arthroscopic partial lateral meniscectomy in athletes: a case report.

We present a patient with a severe chondrolysis after arthroscopic partial lateral meniscectomy in a 17-year-old high school basketball player. This is a rare but severe complication after arthroscopic partial lateral meniscectomy. At 7 months after the first operation, a second-look arthroscopy showed numerous cartilaginous debris floating in the knee and a high-grade cartilage damage on the lateral compartment of the tibia. This unexpected complication and a consideration of its etiology are shown.

Adolescent↗
PubMed2006

Thioredoxin protects against joint destruction in a murine arthritis model.

Thioredoxin (TRX) is an oxidative stress-inducible biological antioxidant that is highly expressed in the synoviocytes of rheumatoid arthritis (RA) patients. There is much evidence that oxidative stress plays a key role in the inflammation and destruction of RA joints; the functional relationship between TRX and RA remains unknown, however. We therefore investigated the role played by TRX in the inflammatory and joint-damaging processes of RA using a murine model in which arthritis was induced by administering a mixture of anti-type II collagen monoclonal antibodies (mAb) and lipopolysaccharide (LPS). In Wt mice mAb/LPS injection induced neutrophil infiltration, cartilage destruction, and chondrocyte apoptosis within the joints, all of which were dramatically suppressed in TRX transgenic (TRX-Tg) mice. Moreover, the 8-hydoxy-2'-deoxyguanosine (8-OHdG) expression seen in Wt mice after mAb/LPS injection was almost completely inhibited in TRX-Tg mice. The administration of recombinant TRX also suppressed mAb/LPS-induced joint swelling in Wt mice. Taken together, these results suggest that TRX protects against arthritis and is a plausible candidate with which to develop novel therapies for the treatment of RA.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Effects of cyclic mechanical stress on the production of inflammatory agents by nucleus pulposus and anulus fibrosus derived cells in vitro.

STUDY DESIGN: Cyclic mechanical stress (CMS) was applied to cultured nucleus pulposus and anulus fibrosus cells, and the production of inflammatory agents by these cells was evaluated. OBJECTIVE: To investigate the involvement of CMS in the production of inflammatory agents by disc cells. SUMMARY OF BACKGROUND DATA: It has been reported that CMS affects degeneration of the disc. However, little is known about the effect of CMS on the production of inflammatory agents by both cell types in vitro. METHODS: Cells derived from nucleus pulposus and anulus fibrosus of Sprague-Dawley rat tails were cultured with or without CMS applied by the Flexercell Strain Unit (Flexcell International Corp., Hillsborough, NC) in the presence or absence of inflammatory stimulus. Doses of prostaglandin-E2 (PGE2) were measured in the culture supernatants. Semiquantitative evaluations of the expressions of cyclooxygenase (COX)-2 and phospholipase-A2 IIA messenger ribonucleic acids (mRNAs) were also examined. RESULTS: Sole application of CMS on nucleus pulposus and anulus fibrosus cells increased PGE2 synthesis. Coincidence of CMS and inflammatory stimulus synergistically enhanced PGE2 synthesis of both cell types. Anulus fibrosus cells showed a stronger reactivity to these stimuli than nucleus pulposus cells. The expression of COX-2 mRNA of anulus fibrosus cells tended to correlate to the amount of PGE2, whereas COX-2 mRNA was constitutively expressed in nucleus pulposus cells, suggesting that the roles of COX-2 might be different between nucleus pulposus and anulus fibrosus. Phospholipase-A2 IIA mRNA was constitutively expressed in both cell types. CONCLUSIONS: The results of this study suggested that CMS might be involved in the pathomechanism of pain induction of lumbar disc diseases.

Animals↗
PubMed2006

Prolonged down regulation of specific gene expression in nucleus pulposus cell mediated by RNA interference in vitro.

To investigate the efficacies and the longevity of RNA interference in nucleus pulposus cells from rat and human, two reporter luciferase plasmids (Firefly and Renilla) were used. These plasmids were cotransfected with siRNA targeting Firefly luciferase to the nucleus pulposus cells extracted from Sprague Dawley rats and scoliosis patients. The inhibitory effects were evaluated by dual luciferase assay for 3 weeks. Proliferation activity of fibroblast-like cells extracted from the subcutaneous tissue of Sprague Dawley rats and the nucleus pulposus cells were measured by proliferation assay (WST-8 assay) every 2 days after plating. The expression of Firefly luciferase was drastically inhibited both in rats (94.7%) and in humans (93.7%). The inhibitory effects were maintained for 2 weeks and had disappeared completely by 3 weeks. The proliferation activity of nucleus pulposus cells was significantly lower than fibroblast-like cells. We have shown, for the first time, siRNA-mediated gene silencing in rat and human disc cells for a relatively sustained period, probably due to the stability of the nucleus pulposus cells in terms of cell proliferation. The demonstration of this study may allow further exploration of the use of siRNA for scientific research and the treatment of disc degenerative diseases.

Animals↗
PubMed2006

High-resolution MRI using a microscopy coil for the diagnosis of recurrent lateral patellar dislocation.

PURPOSE: Magnetic resonance imaging (MRI) has been commonly used for the preoperative evaluation of recurrent lateral patellar dislocation (RLPD). The purpose of this study was to determine the usefulness of high-resolution MRI (HR-MRI) with a microscopy coil for diagnosing RLPD. MATERIALS AND METHODS: The study group consisted of 15 patients with clinically diagnosed RLPD and 10 normal volunteers. All studies were performed on a 1.5-T MR system. First, conventional MRIs of the whole knee joint were obtained using the knee coil. Then HR-MRI scans using a microscopy coil in the medial aspect of the patella were obtained at the level of the superior pole of the patella, targeting the medial patellofemoral ligament (MPFL). The acquired HR-MRIs with RLPD were reviewed concerning the MPFL injury and the patellar injury. RESULTS: The MPFL was distinguished as a separate ligament, and the layer structure of the patellar cartilage was visualized clearly in all volunteers. The MPFL injury was visualized in 12 cases (87%); it included discontinuity, thickening, and loosening. The patellar injury was visualized in 11 cases (73%), which included dissecans of the medial margin and cartilage injuries. CONCLUSION: HR-MRI with a microscopy coil provides precise information of the MPFL and patellar cartilage injury for the diagnosis of RLPD.

Adolescent↗
PubMed2006

The structural properties of an osteochondral cylinder graft-recipient construct on autologous osteochondral transplantation.

PURPOSE: The purpose of this study was to investigate the changes in structural properties of an osteochondral cylinder graft-recipient construct after autologous osteochondral transplantation. METHODS: A full-thickness cylindrical osteochondral defect (5 mm in diameter and 3 mm in depth) was made on the femoral condyle of a mature female Japanese white rabbit using the Osteochondral Autograft Transfer System (OATS; Arthrex, Naples, FL). The defect was repaired with an osteochondral plug (6 mm in diameter and 3 mm in depth) taken from the contralateral femoral condyle using the OATS. The implanted osteochondral grafts were evaluated immediately after surgery and at postoperative weeks 1, 3, 8, and 12. The stiffness of articular cartilage was analyzed using a tactile sensor system (AXIOM, Fukushima, Japan), which measures stiffness based on changes in resonance frequency when a vibrating tactile sensor touches articular cartilage. The specimens were stained with hematoxylin and eosin and serial sections were examined microscopically. RESULTS: The cartilage stiffness of the graft immediately after surgery was 107,695.1 N/m, which was not statistically different from the normal cartilage stiffness (100,027.5 N/m). The stiffness at postoperative weeks 1, 3, 8, and 12 was 95,386.8, 92,899.3, 95,969.8, and 104,683.7 N/m, respectively. The stiffness at postoperative weeks 1, 3, and 8 was significantly lower than the normal cartilage stiffness and the stiffness at postoperative week 12 was the same as normal cartilage. A new bone formation with an increase of bone trabeculae between the osteochondral cylinder graft and the recipient was observed at postoperative weeks 1, 3, and 8. Thereafter, at postoperative week 12, bone trabeculae decreased to the same level as observed in a normal model due to the progress of bone remodeling. CONCLUSIONS: The stiffness of articular cartilage of the osteochondral graft was normal at the time the graft was initially placed and at postoperative week 12. However, the stiffness at postoperative weeks 1, 3, and 8 was lower than the normal cartilage stiffness. CLINICAL RELEVANCE: Care should be taken when planning the rehabilitation program at an early phase after osteochondral transplantation.

Animals↗
PubMed2006

Far lateral extraforaminal facet cyst causing L5 radiculopathy.

Most synovial cysts of the lumbar spine appear as intraspinal extradural masses adjacent to the facet joint. Almost all symptomatic synovial cysts are located within the spinal canal and or the neural foramen. To our knowledge, only 6 cases of symptomatic extraspinal synovial cysts have been described in the literature. The authors report a case of lumbar radiculopathy caused by a synovial cyst located in the far lateral extraforaminal area. The patient underwent decompression of the L5 nerve root with recapping right isthmectomy and facetectomy. Postoperative recovery was uneventful, and the patient was totally pain free with no motor deficit. Symptomatic synovial cysts are uncommon lesions that are associated with degenerative disease of the spine. Juxtafacet cysts should be considered in the differential diagnosis of space-occupying lesions at the extraforaminal areas. Recapping isthmectomy and facetectomy are useful procedures for a synovial cyst located in the far lateral extraforaminal area.

Cysts↗
PubMed2006

Comparison of posterior and anterior pelvic osteotomy for bladder exstrophy complex.

To compare the correction and maintenance of the pelvic ring after pelvic osteotomy in bladder exstrophy complex, we analyzed all cases performed at our institution. Posterior osteotomy was performed in six patients; anterior or combined osteotomy was performed in four patients. Patients who underwent posterior osteotomy had a mean pubic approximation of 37.3%. The mean was 62.8% in patients undergoing anterior or combined osteotomy. This difference was statistically significant (P<0.05 ). The mean recurrence of separation in pubic diastasis was 90.5% for posterior osteotomy and 41.6% for anterior or combined osteotomy. These results indicate that an anterior or combined pelvic osteotomy corrects and maintains the pelvic ring with a bladder exstrophy complex more effectively than a posterior pelvic osteotomy.

Bladder Exstrophy↗
PubMed2006

Evaluation of impairment of hand function in patients with cervical myelopathy.

Clumsiness of the hands is one of the most common complaints in patients with cervical myelopathy. However, few reports have been published that evaluate hand dysfunction. One hundred and twenty-nine patients (36 women and 93 men) with cervical myelopathy were examined and results compared with those of age- and sex-matched controls. Hand function was evaluated as scores of 10 subtests designed on the basis of various hand activities. Patients with cervical myelopathy obtained significantly lower scores on the hand function test in each age-group than controls. There was good correlation between hand function scores and the extent of cervical myelopathy. Therefore, the hand function test is a useful battery to objectively and quantitatively evaluate impairment of cervical myelopathy, although longitudinal studies are needed to determine its practical usability.

Adult↗
PubMed2006

Joint gap kinematics in posterior-stabilized total knee arthroplasty measured by a new tensor with the navigation system.

BACKGROUND: The management of soft tissue balance during surgery is essential for the success of total knee arthroplasty (TKA) but remains difficult, leaving it much to the surgeon's feel. Previous assessments for soft tissue balance have been performed under unphysiological joint conditions, with patellar eversion and without the prosthesis only at extension and 90 deg of flexion. We therefore developed a new tensor for TKA procedures, enabling soft tissue balance assessment throughout the range of motion while reproducing postoperative joint alignment with the patellofemoral (PF) joint reduced and the tibiofemoral joint aligned. Our purpose in the present study was to clarify joint gap kinematics using the tensor with the CT-free computer assisted navigation system. METHOD OF APPROACH: Joint gap kinematics, defined as joint gap change during knee motion, was evaluated during 30 consecutive, primary posterior-stabilized (PS) TKA with the navigation system in 30 osteoarthritic patients. Measurements were performed using a newly developed tensor, which enabled the measurement of the joint gap throughout the range of motion, including the joint conditions relevant after TKA with PF joint reduced and trial femoral component in place. Joint gap was assessed by the tensor at full extension, 5 deg, 10 deg, 15 deg, 30 deg, 45 deg, 60 deg, 90 deg, and 135 deg of flexion with the patella both everted and reduced. The navigation system was used to obtain the accuracy of implantations and to measure an accurate flexion angle of the knee during the intraoperative joint gap measurement. RESULTS: Results showed that the joint gap varied depending on the knee flexion angle. Joint gap showed an accelerated decrease during full knee extension. With the PF joint everted, the joint gap increased throughout knee flexion. In contrast, the joint gap with the PF joint reduced increased with knee flexion but decreased after 60 deg of flexion. CONCLUSIONS: We clarified the characteristics of joint gap kinematics in PS TKA under physiological and reproducible joint conditions. Our findings can provide useful information for prosthetic design and selection and allow evaluation of surgical technique throughout the range of knee motion that may lead to consistent clinical outcomes after TKA.

Aged↗