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Biomedical subjects

Yoshikazu Ikuta

Publications and source records attributed to Yoshikazu Ikuta.

At least 19 recordsLinked to original sources
PubMed2005

Differential activation of astrocytes and microglia after spinal cord injury in the fetal rat.

BACKGROUND: As the immature spinal cord was nerve growth permissive, we examined glial reactions that influence regeneration of the spinal cord in a fetal rat spinal cord injury model. METHODS: Three, 7, 21, and 35 days after intrauterine surgery, offspring were killed and the thoracic and lumbar spinal cords were carefully removed from the spinal column and then cut into 10 mum longitudinal sections. These sections were stained with hematoxylin-eosin, anti-glial fibrillary acidic protein antibody (GFAP) as a marker of astrocytes, and anti-complement CR3 antibody (OX-42) as a marker of microglia. A cordotomy model in a young adult rat was utilized as a control. RESULTS: In the present study, collagen fibers and scar formation were seen in the severed spinal cords of mature rats, but scar formation was not seen in the fetal rat cordotomy group, regardless of spinal continuity. In the control group, biological activity of GFAP-positive cells increased over time. In the fetal rat cordotomy model, activity elevated slightly immediately after cordotomy, and disappeared shortly thereafter. In the control group, OX-42-positive macrophage-like cells proliferated over time. However, in the fetal rat cordotomy model, OX-42- positive macrophage-like cells were recognized on postoperative days 3 and 7, and then disappeared. At 5 mm from the cordotomy site, reactive microglia were recognized in the white matter of control group spinal cords, but these microglia were not recognized in the fetal rat cordotomy model. CONCLUSIONS: In the present study, collagen fibers and scar formation were seen in the severed spinal cords of adult rats, but scar formation was not seen in the fetal rat cordotomy group. Lack of inflammation and scar formation thus appear advantageous for regeneration of the fetal spinal cord. Between fetal and mature rats, chronological changes in the immunohistochemical reactions of astrocytes and microglia following cordotomy were compared, and the results confirmed many differences. The results of the present study suggest that the presence of activated glial cells around damaged central nervous tissue and the quick disappearance of these cells after injury are important for the repair of damaged central nervous system tissue, and that the role of glial cells in nerve regeneration can change depending on the level of maturity of glial cells or surrounding cells, site of injury, or the state of tissue around the injury.

Animals↗
PubMed2005

Role of simple cold storage in preventing epiphyseal growth plate impairment after replantation surgery in immature rats.

The purpose of this study was to investigate the effect of ischemia time on longitudinal bone growth after replantation, and to evaluate the usefulness of simple cold storage of an amputated limb in preventing epiphyseal growth-plate impairment. A hind-limb replantation model was produced with 5-week-old rats after various ischemia times. With more than 6 hr of warm ischemia, growth disturbance was observed, and extensive necrosis was histologically apparent in the central region of the growth plate of the proximal tibia, even at 1 week postoperatively. Destruction of the growth plate was complete at 4 weeks after surgery. By simple cold storage of the amputated limb, growth disturbance was not observed, even following ischemia for 9 hr, and no abnormal findings were observed histologically. Segmental necrosis and destruction of the growth plate observed histologically suggested the possibility of indirect impairment of the epipyseal chondrocytes due to disturbance of the epiphyseal arterial system, attributable to ischemia. The study confirmed experimentally that cold storage of the amputated part may prevent longitudinal bone-growth disturbance after extension of ischemia time.

Amputation, Traumatic↗
PubMed2004

Bone lengthening for congenital differences of the hands and digits in children.

PURPOSE: We investigated the growth of bones after lengthening to evaluate the effectiveness and usefulness of bone lengthening in congenital hand deficiencies. METHODS: Bone lengthening was performed to treat congenital hand deficiencies including hypoplastic thumb, hypoplasia of the small finger, cleft hand, metacarpal synostosis, brachymetacarpia, symbrachydactyly, and amniotic band syndrome. A total of 15 patients (1-13 years old) underwent lengthening of 23 bones. The average of distraction was 10 mm. The mean follow-up period was 59 months. The length of the bones at follow-up evaluation was measured and then compared with the length of the bones immediately after lengthening. The bone growth after lengthening, the percentage of growth after lengthening, and the growth rate were compared among diagnostic groups. RESULTS: In the cases involving older patients the bone length changed little and the growth plates of these patients closed naturally soon after lengthening. In contrast, in the cases in which the patients were younger than 7 years old the lengthened bones grew continuously. The amount of bone growth was different for each disease in the younger patients. In patients with amniotic band syndrome the lengthened bones grew at the same rate as the bones in the hand. Other diagnoses such as symbrachydactyly had a different growth pattern in the hand. CONCLUSIONS: We conclude that bone lengthening is a reliable method for the correction of congenital differences of the hand. The indications for this procedure must be determined while considering the relationship between the specific disease and subsequent bone growth.

Adolescent↗
PubMed2004

Regional differences in the healing potential of the meniscus-an organ culture model to eliminate the influence of microvasculature and the synovium.

Meniscal healing is well known to be region-specific, and this is thought to be mainly due to its specific vascularity. The purpose of this study was to assess regional differences in the intrinsic healing potential of the meniscus, using an organ culture model to eliminate the influence of microvasculature and the synovium. A full-thickness circular defect, 1.5 mm in diameter, was created in the inner avascular zone in meniscal explants from rabbits. As a control, a column of 1.5 mm in diameter was removed then replanted in the area where it had been obtained (Group C). In the experimental group, a 1.5 mm-diameter meniscal graft obtained from the peripheral zone of the same specimen was implanted in the damaged area (Group T). These meniscal explants were cultured for 2, 4 or 6 weeks, and the relationship between the recipient tissue and the graft was examined using both gross and histological semiquantitative scoring. The 6-week gross-examination showed that the openings were more apparent in Group C, and the score of Group T was significantly higher than that of Group C (P=0.0152). Histologically, the healing responses after both 4 and 6 weeks of incubation were significantly better in Group T than in Group C (P=0.0237, 0.0281). These results using organ culture demonstrate that intrinsic healing potential differs even without the influence of vascular supply and the synovium, indicating that the superior healing potential in the peripheral zone may contribute to the good meniscal healing in this location.

Animals↗
PubMed2004

Interposed autologous nerve segment stimulates nerve regeneration in peripheral nerve allografts in a rat model.

The ability of autologous nerve segments interposed between allografts, to increase the total nerve-gap distance, was studied. Sciatic nerve allografts were carried out in a rat model. A 15-mm nerve gap was repaired with a 25-mm nerve graft (interposed group: allo-auto-allograft; control group: allo-allo-allograft). Cyclosporin was given for 12 weeks. Nerve regeneration was evaluated using the weight of the anterior tibial muscle and histologic, morphometric and immunohistochemical analyses at 12, 13, 14, 15, 16, 20, and 24 weeks. Nerve regeneration in the interposed group was statistically significantly better than that in the control group. The authors concluded that a nerve allograft with interposed autograft may enhance nerve regeneration in this model, because of the migration of host-derived Schwann cells into the graft from not only the proximal and distal host nerve stumps, but also the interposed autograft.

Animals↗
PubMed2004

Corrective valgus osteotomy after free vascularized fibula transfer for the treatment of osteomyelitis at the neck of the femur: case report.

Reconstruction using a free vascularized fibula was performed on a long bony defect after osteomyelitis of the proximal femur. For this type of bone defect, a double-barrel fibular graft is recommended. The authors used this procedure for a 58-year-old male who had osteomyelitis of the left proximal femur. As osteotomy through a transplanted fibula can be safely performed, abduction osteotomy should be considered when coxa vara remains after reconstruction with a free vascularized fibula transfer.

Femur Neck↗
PubMed2003

Transplanted neuronal progenitor cells in a peripheral nerve gap promote nerve repair.

A basic experiment of peripheral nerve regeneration using neuronal progenitor cells embedded in collagen gel was performed in a rat sciatic nerve defect. First, when neuronal progenitor cells derived from the fetal rat hippocampus were cultured in atelocollagen-containing medium, neurospheres positive for anti-nestin antibody were confirmed after 8 days. These cells differentiated into astrocytes positive for anti-glial fibrillary acidic protein (GFAP) antibody, oligodendrocytes positive for anti-galactocerebroside (GalC) antibody and neurons positive for anti-neurofilament 200 (NF200) antibody, and they were capable of extending axons. They also differentiated into Schwann-like supportive cells positive for anti-s100 and anti-p75 antibody. Next, a 15-mm defect was prepared in the sciatic nerve of mature rats, and the nerve was bridged with a silicone tube filled with neuronal progenitor cells (1 x 10(5)) embedded in collagen gel. The transplanted neuronal progenitor cells were labeled in advance with 5-bromo-2-deoxyuridine (BrdU). When the regenerated tissue was examined 6 weeks and 10 weeks after grafting, the number and diameter of myelinated fibers were significantly increased compared with a control tube without neuronal progenitor cells. Action potentials were detected in the regenerated nerve. Also, cells positive for both anti-BrdU antibody and anti-S100 or anti-p75 antibody were observed in the regenerated tissue, and part of the grafted neural stem cells were considered to have differentiated into Schwann cell-like supportive cells. From these results neuronal progenitor cells derived from the fetal rat hippocampus are considered to retain their proliferative and differentiating abilities in collagen gel, and when transplanted to a site of peripheral nerve defect, part of them differentiate into supportive cells and they contributed to promotion of axonal regeneration.

Animals↗
PubMed2003

Second- and third-generation Omniflex modular femoral stem: results 3 to 8 years after surgery.

Primary cementless total hip arthroplasty (THA) using the Omniflex modular femoral stem was conducted on 73 hips in 70 patients. The arc deposition (AD)-type stem was used in 26 hips, and the hydroxyapatite (HA)-type stem was used in 47 hips. The mean follow-up period of patients in the AD group was 78 (range, 61-96) months and that of patients in the HA group was 52 (range, 36-61) months. Clinically, improvement in the Harris hip score occurred in all cases. Thigh pain was reported in 3 (11.5%) AD hips and in 1 (2.1%) HA hip. Radiologically, bone ingrowth fixation was seen in 88.5% of the AD group and in 97.9% of the HA group. No subtrochanteric stress shielding, stem migration of > 2 mm, or revision THA occurred. The second- and third- generation Omniflex stems are useful cementless devices resulting in favorable initial biologic fixation and little bone atrophy at mid-term follow-up.

Aged↗
PubMed2003

Attachment of autogenous tendon graft to cortical bone is better than to cancellous bone: a mechanical and histological study of MCL reconstruction in rabbits.

We analyzed the mechanical and histological variables after the attachment of an autogenous tendon graft to cortical or cancellous bone. We reconstructed the medial collateral ligament of the knee in 33 Japanese white rabbits, using a bone socket procedure. The floor of the bone socket was cortical bone in group A and cancellous bone in group B. Mechanically, the pull-out test showed a tendency towards an increase in maximum failure load, with 10.9 N, 35 N and 37 N in group A, and 11 N, 18 N and 36 N in group B at 2, 4 (statistically significant difference) and 8 weeks after surgery, respectively. Histologically, the attachments were immature at 2 weeks. At 4 weeks, granulations had matured and Sharpey's fiber-like structures were seen. These fibers were more abundant in group A than in group B. At 8 weeks, the attachments in both groups were rather like the normal 4-zone structure. With time, tendon attachments matured in both groups. Our study showed that reattachment of tendons to cortical bone may be bettter than to cancellous bone.

Analysis of Variance↗
PubMed2003

A morphological study of the scaphoid using a mathematical technique and comparative study of the three-dimensional measurements of the scaphoid.

To guide reconstruction of scaphoid non-union, we attempted to create full-scale models of the scaphoid by three-dimensional computed tomography (3D CT) of the healthy side. In this study, we obtained 3D scans of 51 cadaveric hands and studied the difference in morphology between genders and between the left and right sides. The major axis length on a fixed plane and Fourier transformation curve were examined. Ten scaphoid images were also obtained with 3D CT before and after removal from the cadaveric hands. Our findings suggest good correlation between models produced using 3D CT images of the scaphoid alone, and this could serve as an accurate model if the magnification is corrected using the regression line. However, the model using 3D CT images of the intact wrist joint has a large margin of error and its use will not be practical.

Aged↗
PubMed2002

Anterior knee laxity in young women varies with their menstrual cycle.

We studied 16 women 21-23 years old with regular menstrual cycles (28+/-4 days) and no history of knee injury. From their basal body temperatures and the serum concentrations of estradiol and progesterone, the follicular, ovulatory, and luteal phases were delineated. Using a KT-2000 arthrometer, anterior displacement at 89 N and 134 N and anterior terminal stiffness (N/mm) at 134 N were measured two or three times every week over a 4-week period. Eight men 21-23 years old were also measured. In women the anterior displacement at 89 N varied between the follicular and the ovulatory phase and between the follicular and the luteal phase ( P<0.05) and at 134 N between the follicular and the luteal phase ( P<0.05). There were no statistical differences in the anterior displacement with time in men, nor in anterior terminal stiffness in either sex. We conclude that anterior cruciate ligament laxity in women might be dependent on the concentrations of hormones.

Adult↗
PubMed2002

Spontaneous healing of acute anterior cruciate ligament (ACL) injuries - conservative treatment using an extension block soft brace without anterior stabilization.

To evaluate the spontaneous healing capability of acute anterior cruciate ligament (ACL) injuries, conservative treatment was applied in a selected group of 31 patients, who had low athletic demands. Each patient demonstrated a continuous ACL on magnetic resonance imaging (MRI), from the original femoral attachment through the tibial attachment, and an area of high intensity was detected in the substance of the ACL. The injured knees were treated using an extension block soft brace without anterior stabilization for 2-3 months. KT-2000 and MRI examinations were carried out regularly during the follow-up. Twenty-three knees (74%) were revealed to be stable in the follow-up examination, with an average of 16.1 months elapsing since the initial injuries. The KT-2000 side-to-side differences of 20 knees were less than 3 mm, and those of the other 3 knees were more than 3 mm but less than 5 mm. MRI confirmed that 21 injured ACL out of 23 knees maintained a femoral to tibial attachment and showed gradual reductions in image intensity. The positions of the other 2 injured ACL femoral attachments were different from the original femoral attachment: one was attached to the posterior cruciate ligament, and the other was located at the lateral femoral condyle anterior to the original femoral attachment. Eight knees (26%) subsequently required ACL reconstructions due to instability. This study indicates that an acutely injured ACL has healing capability. It also suggests that conservative management of the acute ACL injury can yield satisfactory results in a group of individuals who have low athletic demands and continuous ACL on MRI, provided the patients are willing to accept the slight risk of late ACL reconstruction and meniscal injury.

Adolescent↗
PubMed2002

Effects on articular cartilage of subchondral replacement with polymethylmethacrylate and calcium phosphate cement.

Bone defects were created in rabbit medial femoral condyle in a model where subchondral bone was completely removed or about 2 mm of subchondral bone was maintained. Groups without augmentation and augmented with autogenous bone, polymethylmethacrylate, or calcium phosphate cement were sacrificed at 3, 12, and 24 weeks for evaluation of articular cartilage and observation of bone formation. In the model in which subchondral bone was completely removed, collapse of the subchondral bone together with exfoliation and prolapse of cartilage developed early in all cases. In the model in which 2 mm of subchondral bone was maintained, degeneration of articular cartilage developed at 12 weeks in the group augmented with polymethylmethacrylate, showing a significant difference when compared to the contralateral untreated control group. The group augmented with calcium phosphate cement did not demonstrate any evident difference from the control group. Mechanical properties after subchondral replacement did not differ between the groups augmented with polymethylmethacrylate and calcium phosphate cement, although calcium phosphate cement was considered histologically superior. Calcium phosphate cement was a reliable subchondral replacement material when the bone defect is adjacent to the articular cartilage.

Animals↗