Biomedical subjects

T Muneta

Publications and source records attributed to T Muneta.

At least 19 recordsLinked to original sources

PubMed2006

ED-71, a novel vitamin D analog, promotes bone formation and angiogenesis and inhibits bone resorption after bone marrow ablation.

ED-71, a novel analog of 1alpha,25-(OH)2 D3, increases bone mass to a greater extent than alfacalcidol, an 1alpha,25-(OH)2 D3 prodrug. In this study, we used a murine bone marrow ablation model to compare the effect of ED-71 on bone formation and resorption in vivo with that of 1alpha,25-(OH)2 D3. We discovered that bone matrix remodeling occurring within the first week after bone marrow ablation was enhanced by a single injection of ED-71, but not by 1alpha,25-(OH)2 D3. This enhancement was associated with an increase in bone surface. Trabecular bone resorption occurring from 1 to 2 weeks after the procedure was suppressed by a single injection of ED-71, but not 1alpha,25-(OH)2 D3, with treated mice exhibiting a reduction in osteoclast numbers, despite increases in osteoblast surface. As seen with the single injection, daily administration of ED-71 also enhanced bone modeling. Bone marrow osteoblast differentiation was also augmented by ED-71 pretreatment. Furthermore, ED-71 treatment immediately after bone marrow ablation enhanced angiogenesis within the bone marrow cavity via enhancement of VEGF(120) expression. In this paper, we clearly demonstrate that ED-71 is an orally administered small molecular weight compound with an anabolic effect on bone metabolism.

Animals↗

PubMed2006

Transforming growth factor-beta stimulates IL-1beta-induced monocyte chemoattractant protein-1 expression in human synovial cells via the ERK/AP-1 pathway.

OBJECTIVE AND DESIGN: Transforming growth factor- beta (TGF-beta) has not only a fibrogenic role, but also monocyte/ macrophage chemotactic properties in a synovial joint. However, little is known about the effects of TGF-beta on monocyte chemoattractant protein-1 (MCP-1) expression in human synovial cells under inflammatory status. The aim of this study was to determine whether TGF-modulates MCP-1 production under the chronic inflammation, and to elucidate the cell signaling mechanism involved. MATERIALS AND METHODS: Human synovial cells were exposed to IL-1beta, which mimics the environment of chronic inflammation. Production of MCP-1 protein and expression of MCP-1 mRNA were determined by ELISA and real-time PCR. RESULTS: TGF-beta upregulated the expression of MCP-1 mRNA and protein with or without IL-1beta. TGF-beta and IL-1beta synergistically enhanced MCP-1 gene expression, and an AP-1 binding site was involved in the signal transduction. In addition, MEK inhibitor completely suppressed TGF-beta-induced MCP-1 production. CONCLUSIONS: TGF-beta and IL-1beta synergistically enhance MCP-1 gene expression through the activation of the MEK/ERK1/2 pathways, which leads to AP-1 activation. The impairment of MCP-1 regulation by TGF-beta in resident synovial cells might represent an important mechanism of chronic inflammation and tissue fibrosis in a synovial joint. MCP-1 should be considered a valid target for therapeutic intervention.

Cells, Cultured↗

PubMed2006

Stem cell properties of human periodontal ligament cells.

BACKGROUND AND OBJECTIVE: Stem cells have been used for regenerative therapies in various fields. The proportion of cells that possess stem cell properties in human periodontal ligament (PDL) cells is not yet well understood. In this study, we quantitatively characterized human PDL cells to clarify their stem cell properties, including self-renewal, multipotency, and stem cell marker expression. MATERIAL AND METHODS: PDL cells were obtained from extracted premolar or wisdom teeth, following which a proliferation assay for self-renewal, a differentiation assay for multipotency, immunostaining for STRO-1, and fluorescence-activated cell sorter (FACS) analysis for stem cell markers (including CD105, CD166, and STRO-1) were performed. RESULTS: Approximately 30% of 400 PDL cells were found to possess replicative potential and formed single-cell colonies, and 30% of these colonies displayed positive staining for STRO-1, 20% differentiated into adipocytes and 30% differentiated into osteoblasts. FACS analysis revealed that PDL cells, including cell populations, expressed the stem cell markers CD105, CD166, and STRO-1. CONCLUSION: The findings of this study indicated that PDL cells possess crucial stem cell properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers CD105, CD166, and STRO-1 on their cell surface, although there were some variations. Thus, PDL cells can be used for periodontal regenerative procedures.

Adipogenesis↗

PubMed2004

Induction of cyclooxygenase-1 in cultured synovial cells isolated from rheumatoid arthritis patients.

OBJECTIVE AND DESIGN: The aim of this study was to confirm the involvement of cyclooxygenase (COX)-1 in rheumatoid arthritis (RA). MATERIALS AND SUBJECTS: Synovial cells isolated from arthritic patients were cultured primarily and consecutively for 8 passages. TREATMENT: The cultured synovial cells were incubated with 10 ng/ml of interleukin-1alpha (IL-1alpha) for 6 h. METHODS: The effects of either COX-1 or COX-2 selective inhibitor on prostaglandin E2 (PGE2) production was estimated by enzyme-linked immunosorbent assay (ELISA) and the expression of COX-1 and COX-2 were determined by Western blotting and immunocytochemistry. RESULTS: IL-1alpha-induced PGE2 production in synovial cells isolated from RA in primary culture was inhibited by mofezolac, a selective inhibitor of COX-1, as well as NS-398, a specific inhibitor of COX-2. The similar inhibitory patterns were obtained in the RA-derived synovial cells within 3 passages. However, COX activity in the RA-derived synovial cells after 5 passages was inhibited by NS-398, but not by mofezolac. In contrast, COX activity in primary and consecutively cultured synovial cells isolated from osteoarthritis (OA) or normal arthritis was inhibited by NS-398, but not by mofezolac. Western blot and immunocytochemical analyses of COX-1 and COX-2 in the synovial cells isolated from RA patients within 3 passages showed an induction in both COX-1 and COX-2 expression by IL-1alpha. The induction of both COX-1 and COX-2 was inhibited by dexamethasone. CONCLUSIONS: These experiments demonstrate COX-1 induction in synovial cells isolated from RA patients, suggesting that COX-1 is involved in the progression of RA.

Arthritis, Rheumatoid↗

PubMed2003

Anatomical bases for minimizing sensory disturbance after arthroscopically-assisted anterior cruciate ligament reconstruction using medial hamstring tendons.

The aim of this study was to improve surgical techniques for arthroscopically-assisted anterior cruciate ligament (ACL) reconstruction with minimal sensory disturbance in the infrapatellar and anterior lower leg regions. Thirteen patients with sensory disturbance were examined neurologically, and 51 lower limbs of 26 adult cadavers were examined anatomically to investigate the nerve branches supplying the regions. The region of sensory disturbance was supplied by branches of the medial femoral cutaneous nerve and the saphenous nerve, and the nerves showed a complementary distribution area. After detailed investigation of the positional relationships between the nerve branches and the skin incisions of the operative procedure, it was found that at least one branch of both nerves ran across the longitudinal skin incision (80%) for tendon harvest in the above-mentioned reconstruction. The complicated anatomic variations of the nerve branches preclude their absolute avoidance in any surgical incision, and a completely safe zone could not be found in the present study. However, an oblique incision for the tendon harvest rather than the typical longitudinal incision should be considered to minimize the sensory disturbance.

Adolescent↗

PubMed2003

Effect of hypoxia on monocyte chemotactic protein-1 (MCP-1) gene expression induced by Interleukin-1beta in human synovial fibroblasts.

OBJECTIVE: Rheumatoid arthritis (RA) synovial membrane is characterized by leucocyte infiltration and secretion of chemotactic and proinflammatory factors. Since hypoxia is an important pathogenic factor in inflamed synovium, we examined the effects of hypoxia on monocyte chemotactic protein-1 (MCP-1) expression in human rheumatoid arthritis synovial fibroblasts (RASF) under IL-1beta-stimulated and -unstimulated conditions. METHODS: Synovial fibroblasts were isolated from RA, osteoarthritis (OA) and healthy knee joints and subjected to hypoxia or/and IL-1beta treatment. MCP-1 expression and protein secretion were measured by real-time PCR and ELISA, respectively. RESULTS: Hypoxia reduces MCP-1 expression and protein secretion in RASF. The same response to hypoxia was found in OA and healthy SF cultures. Treatment with actinomycin D showed that hypoxic down-regulation of MCP-1 expression was due to a decrease in transcription, since the half-life of MCP-1 mRNA was unchanged. A cycloheximide study demonstrated that de novo protein synthesis was not required for the hypoxic effect. The decrease in MCP-1 expression by hypoxia was mimicked by cobalt chloride in unstimulated RASF with no effect on IL-1beta-activated MCP-1, suggesting differences in the signaling mechanisms. The analysis of IkappaB degradation and NF-kappaB translocation revealed that hypoxia did not affect IL-1beta activation of NF-kappaB. CONCLUSION: Hypoxia regulates MCP-1 expression under both basal and cytokine-stimulated conditions, suggesting that reduced oxygen supply is an important factor that mediates chemotaxis of monocytes to the area of inflammation.

Arthritis, Rheumatoid↗

PubMed2003

Factors which affect the progression of osteoarthritis after rotational acetabular osteotomy.

We have investigated the factors which affect the progression of osteoarthritis after rotational acetabular osteotomy (RAO). Between 1984 and 1998, we treated 60 dysplastic hips by RAO. The mean age at surgery was 31.6 years (13 to 51) and the mean period of follow-up was 4.6 years (2 to 9.5). The thickness of the articular cartilage on the weight-bearing area, pre- and postoperative acetabular cover, and the sphericity of the femoral head were used for radiological assessment. The osteoarthritis did not progress in 39 hips. Significant factors which affected the radiological grade included sphericity of the femoral head and the postoperative acetabular cover. The surgical approach and preoperative acetabular cover did not affect the progression of osteoarthritis. Patients were divided into two groups according to the surgical approach used, either conventional (23 hips) or modified (37 hips). Significant factors included the postoperative acetabular cover in the modified approach, and the sphericity of the femoral head in the conventional approach. It is critical that the postoperative cover is sufficient, especially when RAO is carried out using our modified technique.

Acetabulum↗

PubMed2001

The relationship between postoperative ligament balance and preoperative varus deformity in total knee arthroplasty.

We hypothesize that in knees with severe varus deformities, varus-valgus ligament imbalance tends to remain postoperatively after total knee arthroplasty. The purpose of this study was to evaluate the correlation between preoperative varus deformity and postoperative ligament balance quantitatively measured by stress radiograph using Telos SE in total knee arthroplasty. In this study, 44 knee arthroplasties in 32 patients were evaluated. We defined the angle in varus and valgus stress as "varus angle" and "valgus angle," and the sum of varus angle and valgus angle as "sum of varus-valgus angle." There was a significant correlation between preoperative lateral femoral angle and varus angle (p < 0.0001, r = 0.56), which means that postoperative ligament imbalance tends to remain in knees with preoperative varus deformities. There was a significant correlation between the postoperative period and the sum of varus-valgus angle, which suggests that knees with total knee arthroplasty have potential to increase laxity postoperatively.

Aged↗

PubMed2000

Notchplasty in anterior cruciate ligament reconstruction: an experimental animal study.

The purpose of this study was to evaluate the effects of a notchplasty on the biomechanical and histological properties of the anterior cruciate ligament (ACL) and changes in patellar articular cartilage. We used an in situ freeze-thaw model for the ACL reconstruction performed with or without notchplasty in 36 Japanese white rabbits. The cross-sectional area of the regenerated ACLs without a notchplasty (6.4 +/- 0.4 mm(2)) was statistically smaller than that of the ACLs with a notchplasty (7.0 +/- 0.3 mm(2)), and the cross-sectional area of the normal ACLs (5.4 +/- 0.5 mm(2)) was statistically smaller than that of both other types. However, the mechanical strength of the ACL with the notchplasty was identical to that of the ACL without a notchplasty. Although the notchplasty areas were covered with fibrous scar tissue, caliper measurement and histological examination showed no obvious osteochondral reconstitution in the notchplasty sites of any of the specimens. Regarding the deleterious effect of notchplasty on patellar articular cartilage, the extent of the slight degenerative changes was about the same in the group with a 1-mm notchplasty and in the control group.

Animals↗

PubMed1999

Anatomic basis of chronic groin pain with special reference to sports hernia.

Chronic pain on the ventral surface of the scrotum and the proximal ventro-medial surface of the thigh especially in athletes has been diagnosed in various ways; recently, in Europe the concept of "sports hernia" has been advocated. However, since few reports discuss the detailed course of the nerves in association with the pain, we examined the cutaneous branches in the inguinal region in 54 halves of 27 adult male cadavers. From our results, in addition to the cutaneous branches from the ilioinguinal n. (in 49 of 54: 90.7%), cutaneous branches originating from the genital branches of the genitofemoral nerve were found in the inguinal region in 19 of 54 halves (35.2%). In 7 cases (in 7 of 54: 13.0%) the genital branch and the ilioinguinal nerve united in the inguinal canal. In 6 cases the genital branch pierced the inguinal lig. to enter the inguinal canal, and in three cases the genital branch pierced the border between the ligament and the aponeurosis of the obliquus externus m. to be distributed to the inguinal region. Therefore, the courses of the genital branches vary considerably, and may have a very important role in chronic groin pain produced by groin hernia. In addition, entrapment by the ligament may be a reasonable candidate for the cause of chronic groin pain.

Adult↗

PubMed1999

Intra-articular detachment of the Endobutton more than 18 months after anterior cruciate ligament reconstruction.

We report a case of detachment of an Endobutton (Acufex Microsurgical, Mansfield MA) used for femoral fixation of a reconstructed anterior cruciate ligament. The Endobutton, which was confirmed to be in place on the suprapatellar space of the femur by radiograph 18 months postoperatively, was found in the popliteal space by radiograph 25 months after surgery. This is a rare complication, but our case suggests that the Endobutton should not be fixed too distal close to the femoral groove.

Adult↗

PubMed1999

The long-term effects of tibial drill hole position on the outcome of anterior cruciate ligament reconstruction.

Fifty-three cases of anterior cruciate ligament reconstruction were classified into two groups depending on the tibial drill hole position: in the anterior group, the center of tibial drill hole was positioned anteriorly to the dome of the intercondylar notch (Blumensaat's line), and in the posterior group, it was positioned posteriorly to the Blumensaat's line. Knee extension loss in the anterior group was significantly greater at 1 and 2 years postoperatively than that of the posterior group. However, there were no differences between the anterior and posterior groups 3 to 5 years postoperatively. No significant differences in anterior laxity were seen from 1 to 4 years postoperatively. After more than 5 years, anteroposterior translation of the anterior group was significantly greater than that of the posterior group. In the anterior group, extension was restricted in the early postoperative period. At latest follow-up more than 5 years postoperatively, anterior laxity in the posterior group was significantly less than that in the anterior group.

Adolescent↗

PubMed1999

Electron microscopic evaluation of the effects of stress-shielding on maturation of the mid-substance and ligament-bone junction of the reconstructed anterior cruciate ligament in rabbits.

To analyze the effects of stress-shielding on graft maturation after the anterior cruciate ligament (ACL) reconstruction, autogenous ACL reconstruction using Achilles tendon was performed in rabbits. Two-end fixation with a ligament augmentation device (LAD), as a stress-shielding model (SS group), and pull-out fixation with Leeds-Keio artificial ligaments (L-K ligament), as a non-stress-shielding model (non-SS group), were investigated. Intact ACL was used as the control. Specimens were harvested 6 mon postoperatively, and the analysis was focused on collagen fibril maturation in the mid-substance and bone-anchoring pattern in the bone tunnel, under light and transmission electron microscopy. The density of collagen fibrils in the control was lower than that in both experimental groups (p<0.01). The per cent collagen area in the control was higher than that in the SS (p<0.01) and the non-SS group (p< 0.05). The per cent collagen area in the non-SS group was higher than that in the SS group (p<0.05). At the ligament-bone interface, intracellular calcification of the degenerated chondrocytes occurred in the non-SS group, while in the SS group hydroxyapatite deposits were observed only in the extracellular matrix. These results show unfavorable influence of stress-shielding on graft maturation not only in the mid-substance but also at the ligament-bone junction.

Journal Article↗

PubMed1999

Two-bundle reconstruction of the anterior cruciate ligament using semitendinosus tendon with endobuttons: operative technique and preliminary results.

We carried out two-bundle reconstruction of the anterior cruciate ligament (ACL) using multi-strand semitendinosus tendon for the purpose of getting better stability under aggressive rehabilitation by putting the graft in the normal anatomy with minimized notch-plasty. The drill guide position was determined using two-directional radiography in hyperextension. The two-bundle procedure was performed using the inside-out technique for grafting and two Endobuttons (Acufex Microsurgical, Mansfield, MA) for femoral graft fixation. The clinical outcomes 2 years postoperatively of 54 of 62 consecutive patients were reported. The preliminary results suggested that the two-bundle procedure showed a better trend with respect to anterior stability compared with those of our previous experience using the single-bundle technique under the same aggressive rehabilitation. The two-bundle procedures have several theoretical advantages over single-bundle with multi-strand tendon graft. The present two-bundle reconstruction is recommended to result in better anterior stability with minimized notch-plasty and with no serious complications.

Adult↗

PubMed1999

A technique for reconstruction of the medial patellofemoral ligament.

Additional medial patellofemoral ligament reconstruction was performed successfully on six consecutive patients with recurrent dislocation of the patella because of residual patellar instability after medial transfer of the tibial tubercle. A technique for medial patellofemoral ligament reconstruction is described, and complications and postoperative management are discussed. The reconstruction was performed using a double strand hamstring tendon graft in five patients and iliotibial allograft in one. Good stabilization of the patella was achieved in all six patients, resulting in improved confidence in higher levels of activity. The satisfactory outcome of additional medial patellofemoral ligament reconstruction suggests the possibility that the procedure may be part of the optional procedure in proximal realignment for recurrent dislocation of the patella.

Adolescent↗

PubMed1998

Dynamic motion study of the whole lumbar spine by videofluoroscopy.

STUDY DESIGN: Dynamic lumbar flexion-extension motion was assessed by videofluoroscopy. OBJECTIVES: To identify the motion patterns of the whole lumbar spine in normal subjects and in patients with low back pain or spondylolisthesis during actual movement. SUMMARY OF BACKGROUND DATA: Assessment of lumbar instability on terminal radiographs is controversial. Information regarding spinal kinematics during actual movement in vivo is scarce. METHODS: Fluoroscopic lumbar sagittal motion videos were recorded in volunteers (n = 13; mean age, 22.3) and in patients with chronic low back pain (n = 8; mean age, 43.5) and degenerative spondylolisthesis (n = 8; mean age, 63.1) while the subjects bent forward from a standing neutral position (eccentric motion) and then returned to the original position (concentric motion). The videos recorded approximately 8 seconds of motion and were converted to still images at 5 frames per second. Disc angles from the horizontal line were measured to estimate sagittal rotation of each segment. Disc degeneration was evaluated on T2-weighted midsagittal magnetic resonance image. RESULTS: In the volunteer group, six exhibited sequentially spreading motion, four exhibited simultaneous motion, and three showed an altered motion-spreading pattern in the eccentric phase. The first two patterns were considered normal. Six (67%) of the patients with chronic low back pain also showed normal patterns, but seven (88%) of the patients with degenerative spondylolisthesis showed disordered patterns. The order of motion in the concentric phase was also different among the three groups. Prolonged deflection of the slipped segment was observed more frequently in the patients with degenerative spondylolisthesis. Disc degeneration was not always associated with motion-spreading order and the motion patterns. CONCLUSION: Segmental instability influences the whole lumbar motion in patients with degenerative spondylolisthesis. The patients with chronic low back pain did not show a significant difference when compared with the volunteers.

Adult↗

PubMed1998

Regression of cervical disc herniation observed on magnetic resonance images.

STUDY DESIGN: A retrospective study of cervical disc herniation using results of repeated magnetic resonance imaging examinations. OBJECTIVES: To clarify the cervical disc herniation morphological changes over time in order to establish a strategy for treatment. SUMMARY OF BACKGROUND DATA: In the authors' previous magnetic resonance imaging follow-up study of patients with lumbar disc herniation, spontaneous regression was observed in the sequestration-type lesions, and it was found that the tendency toward regression differed based on the anatomic position of extruded disc material. METHODS: Thirty-eight patients with cervical disc herniation who underwent repeated magnetic resonance imaging examinations were studied. The changes over time in herniated disc size were evaluated using this imaging technique. Evaluation showed the characteristics of those in whom spontaneous regression was found, such as extrusion pattern, and the clinical outcome was evaluated by symptoms. RESULTS: In 15 patients (40%), the volume of herniated material was decreased. The interval from onset of symptoms to the initial examination was significantly shorter in the regression group than in the group that showed no change in disc herniation. By extrusion pattern, cervical disc herniation, which was divided into migration type on sagittal view and lateral type on axial view, most frequently exhibited spontaneous regression. All of the patients with radicular pain and upper limb amyotrophy were treated successfully with conservative therapy. CONCLUSION: Although the possibility of the combination of hemorrhage and disc material could not be denied, active resorption of herniated material probably occurred during the acute phase. Extruded material exposed to the epidural space may be resorbed more quickly than that beneath the ligament. Vascular supply probably plays a role in the mechanism of resorption. The phase and position of extrusion were the significant factors affecting cervical disc herniation resorption. It was demonstrated that examination performed during the acute phase using magnetic resonance imaging is necessary for elucidation of the pathogenesis of cervical disc herniation, and that migrating, lateral-type herniations regress so frequently that conservative treatment should be chosen not only for patients with radicular pain, but also for those with upper limb amyotrophy.

Adult↗

PubMed1998

Contrast-enhanced magnetic resonance imaging in conservative management of lumbar disc herniation.

STUDY DESIGN: This study was designed to investigate the morphologic changes in contrast-enhanced magnetic resonance imaging that occur during conservative treatment of patients with unilateral leg pain resulting from herniated nucleus pulposus without significant lumbar canal stenosis. OBJECTIVES: To compare the morphologic results with clinical outcomes to ascertain whether enhanced magnetic resonance imaging contributes to the management of lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Contrast-enhanced magnetic resonance imaging has already been reported to be useful in the postoperative examination of the lumbar spine and in visualization of symptomatic nerve roots. However, there have been few reports about its usefulness in the conservative management of herniated nucleus pulposus or about the correlation between herniated nucleus pulposus regression and enhanced effect. The study population consisted of 48 patients with radiculopathy. All patients primarily reported unilateral leg pain, and 94% had positive tension signs. Additionally, 38% exhibited muscle weakness corresponding to the symptomatic nerve root. METHODS: All patients were studied twice or more using gadolinium-magnetic resonance imaging during conservative therapy, at a mean interval of 191 days. Changes in the size of the herniated nucleus pulposus on precontrast images fell into four categories, with changes in enhancement on postcontrast images classified into two categories: "enlargement" and "no change." RESULTS: In all cases of migrating type herniated nucleus pulposus, circular enhancement was seen on postcontrast images. In 17 of 22 cases, the enhanced area gradually thickened and intruded into the migrated disc materials as the size of the herniated nucleus pulposus decreased; the herniated nucleus pulposus disappeared in nine cases and showed a marked decrease in seven cases. These cases showed good clinical courses of sciatica. In the other five patients, in whom there were no changes in the enhanced area, there was less of a tendency for the herniated nucleus pulposus to decrease in size, and there were poorer clinical results. In six cases of extruding-type herniated nucleus pulposus, no enhanced effects were observed throughout the follow-up period. The other 20 cases showed enhancement that was relatively weaker than that of migrating disc herniation. Extension or expansion of the enhanced area was observed in the follow-up images of 15 cases, though only four showed obvious changes in the size of the herniated nucleus pulposus. These 15 cases had better clinical results than the other cases, in which enhanced effects did not change or were not observed. CONCLUSION: Contrast-enhanced magnetic resonance imaging is a useful prognostic parameter, and multiple use contributes to the proper management of lumbar disc herniation.

Adult↗