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Biomedical subjects

Shinya Kawai

Publications and source records attributed to Shinya Kawai.

At least 19 recordsLinked to original sources
PubMed2005

An experimental model of peripheral nerve adhesion in rabbits.

We studied the effects of peripheral nerve adhesion in a rabbit sciatic nerve model. After nerve exposure, its adventitial layer was sutured with 8-0 nylon to the nerve bed, which had been cauterised to promote adhesion. Nerve kinematics, electrophysiology, blood flow and histology were assessed. Rabbits in which Fontana's bands were visible as normal through the epineurium, classified as a nonadhesion group (group I), lacked intraneural fibrosis. In this group, nerve conduction and nerve blood flow were well maintained. Rabbits in which Fontana's bands could not be seen were classified as the adhesion group (group II). This group was classified into two levels pathologically; thickening of epineurium and perineurium was observed but no endoneurial fibrosis (group IIa), and endoneurial fibrosis (Wallerian degeneration, myelin sheath thinning and fibrosis between nerve fibers) was noted (group IIb). Compound muscle action potentials (CMAP) were reduced in amplitude and blood flow was significantly decreased at adhesion sites in group IIb. In conclusion, adhesion of peripheral nerve to surrounding tissues results in fibrosis in the nerve that contributes to peripheral nerve dysfunction.

Action Potentials↗
PubMed2005

Donor cell engraftment in recipient lymphoid tissues after rat limb allograft.

BACKGROUND: The movement of cells from a transplanted tissue into the host organs, the so-called systemic chimerism, is a phenomenon known to occur and be associated with the development of immunologic tolerance in allotransplantation cases. The purpose of this study was to identify donor cell engraftment in recipient lymphoid tissues after performing rat hind limb allograft. MATERIALS AND METHODS: Fifty-five whole-limb allotransplantations were performed in sex-mismatched pairs of rats. Syngeneic male Lewis and allogeneic Dark Agouti donors were transplanted to female Lewis recipients. FK506 was used for immunosuppression. Donor male cells could be identified in the recipient female tissues by semiquantitative polymerase chain reaction analysis for a Y chromosome-specific DNA sequence. Chimerism was assessed at 1, 24, and 48 weeks after transplantation. RESULTS: There was no rejection episode in any of the limb grafts. Although levels of chimerism were highly variable in each lymphoid tissue, a gradual increase was noticed in all during the course of time. At 1 week after the transplant period, only intrasplenic chimerism was at high level (1%) in three groups. At 48 weeks after the transplant, all recipients with allografts showed very high level (10%) of chimerism in the bone marrow. Two, two, and two of six recipients showed very high levels in the spleen, lymph node, and liver, respectively, at 48 weeks. Intrathymic chimerism was higher at 24 weeks after transplant rather than at 48 weeks. CONCLUSION: We demonstrated donor cell engraftment into recipient lymphoid tissues after successful whole limb transplantation. We conclude that limb allograft can work as a vascularized carrier for the bone marrow transplantation, provide a continuous source of donor cells and contribute to chimerism in the recipient.

Animals↗
PubMed2005

Factors affecting ambulatory status and survival of patients 90 years and older with hip fractures.

UNLABELLED: This study was done to assess the long-term functional outcome of very elderly patients with hip fractures, to determine whether bone mineral density and prevalent vertebral fractures could affect mortality and ambulatory status, and to examine which patient characteristics reported in the literature are predictive of patient mortality and ambulatory status. Seventy-four patients 90 years and older with hip fractures were analyzed and followed up for at least 4 years or until death. The mean age of the patients was 92.8 years and all were treated surgically. Walking ability before injury was better than at discharge; walking ability decreased during the first year after discharge, but thereafter reached a plateau. The predictors of survival were the preoperative American Society of Anesthesiologists score, walking ability, fracture type, type of surgery, and the number of prevalent vertebral fractures on admission. Dementia and the number of prevalent vertebral fractures were predictors of the recovery of walking ability. Type of surgery and fracture type are collinear variables, and because it is difficult to separate the effects of one versus the other, additional well-designed, randomized studies on the effect of the type of surgery and fracture type on outcome are needed. LEVEL OF EVIDENCE: Prognostic study, Level II-1 (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Absorptiometry, Photon↗
PubMed2004

Chondrogenic differentiation of murine embryonic stem cells: effects of culture conditions and dexamethasone.

Pluripotent embryonic stem (ES) cells have the capability to differentiate to various cell types and may represent an alternative cell source for the treatment of cartilage defects. Here, we show that differentiation of ES cells toward the chondrogenic lineage can be enhanced by altering the culture conditions. Chondrogenesis was observed in intact embryoid body (EB) cultures, as detected by an increase in mRNA levels for aggrecan and Sox9 genes. Collagen IIB mRNA, the mature chondrocyte-specific splice variant, was absent at day 5, but appeared at later time points. Dexamethasone treatment of alginate-encapsulated EB cultures did not have a strong chondrogenic effect. Nor was chondrogenesis enhanced by alginate encapsulation compared to simple plating of EBs. However, disruption of day 5 EBs and culture as a micromass or pelleted mass, significantly enhanced the expression of the cartilage marker gene collagen type II and the transcription factor Sox9 compared to all other treatments. Histological and immunohistochemical analysis of pellet cultures revealed cartilage-like tissue characterized by metachromatically stained extracellular matrix and type II collagen immunoreactivity, indicative of chondrogenesis. These findings have potentially important implications for cartilage tissue engineering, since they may enable the increase in differentiated cell numbers needed for the in vitro development of functional cartilaginous tissue suitable for implantation.

Aggrecans↗
PubMed2004

RETRACTED: Comparative efficacy of hormone replacement therapy, etidronate, calcitonin, alfacalcidol, and vitamin K in postmenopausal women with osteoporosis: The Yamaguchi Osteoporosis Prevention Study.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor in Chief because of the stated concerns listed below. This article was accepted for publication by a previous editor and editorial board, at a time when submissions and documentation were in paper form, prior to the transition of The American Journal of Medicine to a digital submission and review process. These records are no longer extant and consequently we are unable to review the comments of the reviewers and editors involved at that time. We have attempted to contact the authors regarding these concerns and received no response. We are therefore retracting this article since the evidence presented below strongly argues for scientific misconduct. The integrity of these publications is severely compromised by wide-ranging and serious concerns about governance, ethics, authorship, implausible study conduct, implausible workload, discrepant participant numbers and treatment groups, impossible data, implausible data, implausible outcome data, and discrepant methodology.

Adjuvants, Immunologic↗
PubMed2004

Neurospheres induced from bone marrow stromal cells are multipotent for differentiation into neuron, astrocyte, and oligodendrocyte phenotypes.

Bone marrow stromal cells (MSCs) can be expanded rapidly in vitro and have the potential to be differentiated into neuronal, glial and endodermal cell types. However, induction for differentiation does not always have stable result. We present a new method for efficient induction and acquisition of neural progenitors, neuronal- and glial-like cells from MSCs. We demonstrate that rat MSCs can be induced to neurospheres and most cells are positive for nestin, which is an early marker of neuronal progenitors. In addition, we had success in proliferation of these neurospheres with undifferentiated characteristics and finally we could obtain large numbers of neuronal and glial phenotypes. Many of the cells expressed beta-tubulin III when they were cultivated with our method. MSCs can become a valuable cell source as an autograft for clinical application involving regeneration of the central nervous system.

Animals↗
PubMed2004

Dexamethasone induces human spinal ligament derived cells toward osteogenic differentiation.

Ossification of spinal ligament is characterized by heterotopic bone formation in the spinal ligaments that are normally composed of fibrous tissues. The pathogenesis of ossification of spinal ligament has been suggested to be associated with osteogenic differentiation of the spinal ligament cells. In order to address this hypothesis, cells derived from human spinal ligament were investigated for their osteogenic potential by the treatment of dexamethasone in vitro. Yellow ligaments were obtained from patients with spinal disorders except ossification of spinal ligament during surgery, and the adhering tissues were removed completely. Most of the ligament cells treated with vehicle exhibited a fibroblast-like spindle shape, while the dexamethasone-treated cells acquired a polygonal morphology. Growth of the ligament cells was suppressed by dexamethasone at a high concentration. Some of the vehicle treated-cells were alkaline phosphatase-positive, and dexamethasone increased the alkaline phosphatase-positive cells and alkaline phosphatase activity in the cells. Northern blot analysis demonstrated that mRNAs expression of pro-alpha1(I) collagen and alkaline phosphatase were promoted by dexamethasone. Analysis by reverse transcription-polymerase chain reaction showed that expression of osteocalcin mRNA was detected in the dexamethasone-treated cells but not in the vehicle-treated cells, and dexamethasone-induced osteocalcin mRNA expression was promoted by 1,25-dihydroxyvitamin D(3). Finally, mineralization of extracellular matrix in the cells was induced by the presence of dexamethasone and 1,25-dihydroxyvitamin D(3). These results suggest for the first time that dexamethasone has a possible involvement in the osteoblastic differentiation of human spinal ligament cells.

Alkaline Phosphatase↗
PubMed2004

A giant rheumatoid nodule.

Subcutaneous rheumatoid nodules occur commonly in advanced cases of rheumatoid arthritis and are the most common extra-articular lesion of this disease. We present a case of a very unusual giant rheumatoid nodule that developed on the lateral side of a knee. The case was devoid of systemic symptoms of arthritis and the lesion was limited to a rheumatoid nodule. The nodule was successfully treated by surgical excision. However, other new nodules developed in her hand. Her clinical course has not been satisfactory.

Aged↗
PubMed2004

Distal-type cervical spondylotic amyotrophy: assessment of pathophysiology from radiological findings on magnetic resonance imaging and epidurally recorded spinal cord responses.

STUDY DESIGN: Six cases with distal-type cervical spondylotic amyotrophy are reported. OBJECTIVE: To investigate the pathophysiology of distal-type cervical spondylotic amyotrophy from magnetic resonance imaging and intraoperative evoked spinal cord responses. SUMMARY OF BACKGROUND DATA: Cervical spondylotic amyotrophy had a characteristic clinical symptom of severe muscular atrophy with no or insignificant sensory deficit. Selective ventral root lesions or intrinsic spinal cord lesions have been proposed as the pathophysiology of cervical spondylotic amyotrophy, but they have not been well understood. METHOD: Six patients with distal-type cervical spondylotic amyotrophy were described, and their magnetic resonance imaging and evoked spinal cord potentials after median nerve, motor cortex, and spinal cord stimulation were investigated. RESULTS: Sagittal T2-weighted magnetic resonance imaging showed high signal intensity change within the spinal cord at C4-C5, C5-C6, and C6-C7. All patients underwent laminoplasty. The attenuation of postsynaptic potentials with preserved presynaptic potentials at C4-C5, C5-C6, and C6-C7 was characteristic in the evoked spinal cord potentials after median nerve stimulation. The amplitude of the evoked spinal cord potentials after median nerve stimulation was preserved at C2-C3. This means that lateral posterior column in the spinal cord had less or no involvement in distal-type cervical spondylotic amyotrophy. Concomitant hyperactivity of the patellar tendon reflex was correlated with the abnormality in the evoked spinal cord potentials after transcranial electric stimulation. CONCLUSIONS: The results suggest a longitudinal gray matter lesion as one pathophysiologic feature, and that less damage to the lateral posterior column is the reason for the preservation of sensory function in the patients with distal-type cervical spondylotic amyotrophy described in this study.

Aged↗
PubMed2004

Microvascular anastomosis through the tibial tunnel: a new technique in free-tissue transfer to the leg.

Free-tissue transfer to a severely traumatized leg has a high rate of vascular complications. We present three successful cases using a new technique of microvascular anastomosis through the tibial tunnel. Because of the unavailability of anterior tibial artery due to posttraumatic vascular disease, donor vascular pedicles were passed posterior to the tibia through the tibial tunnel and anastomosed to the posterior tibial artery or its branch in an end-to-end fashion. The flaps survived perfectly, without any vascular complication. This technique represents a safe route, and the shortest route, to an expected anastomosis point. Our technique is indicated especially in cases with a single-vessel leg.

Adult↗
PubMed2004

Nerve root distribution of deltoid and biceps brachii muscle in cervical spondylotic myelopathy: a potential risk factor for postoperative shoulder muscle weakness after posterior decompression.

To investigate the nerve root distribution of deltoid and biceps brachii muscle, compound muscle action potentials (CMAPs) were recorded intraoperatively following nerve root stimulation in cervical spondylotic myelopathy. A total of 19 upper limbs in 12 patients aged 55-72 years (mean, 65.5 years) with cervical spondylotic myelopathy were examined. CMAPs were recorded from deltoid and biceps brachii muscle following C5 and C6 root stimulation. Although both C5 and C6 roots were innervated for deltoid and biceps brachii muscle in all subjects, the amplitude ratio of CMAPs (C5/C6) differed individually depending on the symptomatic intervertebral levels of the spinal cord. The C5 root predominantly innervated both deltoid and biceps brachii in patients with symptomatic cord lesions at the C4-C5 intervertebral level compared to patients with symptomatic cord lesions at the C5-C6 intervertebral level. Although no patients sustained postoperative radiculopathy in our study, severe weakness and unfavorable recovery are expected when the C5 root in patients with C4-C5 myelopathy is damaged. From the electrophysiological aspect, C4-C5 cord lesions are likely to be a potential risk factor for postoperative shoulder muscle weakness in patients with compressive cervical myelopathy.

Action Potentials↗
PubMed2004

Effects of cessation of immunosuppression on skeleton reconstructed by vascularized bone allograft in rats.

In the present study, we investigated the effects of cessation of immunosuppression on skeleton reconstructed by vascularized allogenic bone transplantation in a rat tibio-fibula graft model. Twelve-week-old male 25 Dark Agouti rats with the major histocompatibility antigen (MHC) RT1a were used as donors and age-matched male 25 Lewis rats with MHC RT1l were used as recipients. Among them, 20 rats were randomly allocated to 8-week cyclosporine A (CsA) followed by 8-week CsA vehicle group or continuous 16-week CsA group. The remaining 5 rats received CsA for 8 weeks followed by no further treatment for next 40 weeks (long-term observation group). In the CsA followed by vehicle group as well as the continuous CsA group, the structure of the reconstructed bones was maintained, though the transplanted bones in former group were found to be partly non-vital. The CsA followed by vehicle group had higher bone mineral density of the transplanted bones and stronger strength of the reconstructed bones than the continuous CsA group. In the long-term observation group, the structure of the reconstructed bones was still maintained and the transplanted bones were almost vital. These results suggest that long-term strong immunosuppression may not be necessary for successful reconstruction of large bone defect by vascularized bone allograft.

Absorptiometry, Photon↗
PubMed2004

Role of vascularised tissue transfer after oncological resection in the upper extremity.

We reviewed 12 patients who had had vascularised tissue transfer after oncological resection in the upper extremity. All patients had immediate reconstruction, and one had a double tissue transfer. Tissues used were skin flaps, free muscles, and vascularised fibulas, for resurfacing the wound, motor recovery, and reconstruction of large bony defects, respectively. All the patients returned early to their daily activities. Although local recurrences were encountered in two patients, they were again rendered disease-free by salvage operations. Two patients had secondary reconstructions using pedicle latissimus dorsi flaps for late problems, including one of the two patients who developed a local recurrence. The mean functional score using the system devised by the Musculoskeletal Tumor Society was 84%. All the upper extremities were successfully rescued with satisfactory function. Vascularised tissue transfer was invaluable for achieving both curative resection of the tumour and a useful upper extremity.

Adolescent↗
PubMed2004

Posttraumatic radioulnar synostosis treated with a free vascularized fat transplant and dynamic splint: a report of two cases.

Two cases of posttraumatic radioulnar synostosis are presented. The patients were treated with excision of the cross-union and interposition of a free vascularized fat transplant. A newly devised pronation-supination dynamic splint was employed for 3 months postoperatively in both patients. After a 1-year postoperative follow-up, an increased range of motion was restored in both cases, and there was no evidence of recurrent synostosis formation in subsequent radiographs. We suggest that an interposed vascularized fat graft may be an ideal biologic barrier to fill the space created by cross-union excision.

Adult↗
PubMed2004

The treatment of far-out foraminal stenosis below a lumbosacral transitional vertebra: a report of two cases.

Far-out foraminal stenosis with radiculopathy caused by bony spur formation secondary to anomalous articulation between the transverse process and the sacral ala is rarely reported. We report two cases of unilateral far-out foraminal entrapment of the L5 spinal nerve below a transitional vertebra, with a review of the literature. The objective of this work was to describe the management of a rare far-out foraminal stenosis below a transitional vertebra and to evaluate the surgical and conservative procedures and results. In a previous article, decompression was performed through an anterior approach. However, we report no difficulty with decompression using a posterior approach for one patient. The diagnosis was confirmed with computed tomography, magnetic resonance imaging, and selective radiculography. First, selective nerve root blocks were performed in two cases for the purpose of nonoperative treatment. After failure of conservative treatment with selective nerve root block, one patient underwent posterior decompression by resection of the bony spur using a posterior approach. One patient obtained good relief of radicular pain with only selective nerve root block. The other patient obtained good relief of radicular pain after posterior decompression was performed. Posterior decompression through the posterior approach is an easy, safe, and useful treatment for radicular pain caused by an L5 nerve far-out foraminal stenosis below a transitional vertebra when conservative treatments have failed to obtain good relief of radicular pain.

Adult↗