Biomedical subjects

Tsuyoshi Kadosawa

Publications and source records attributed to Tsuyoshi Kadosawa.

5 recordsLinked to original sources

PubMed2003

Bone ingrowth fixation of artificial intervertebral disc consisting of bioceramic-coated three-dimensional fabric.

STUDY DESIGN: The bone-bonding characteristic of the new artificial intervertebral disc consisting of bioceramic-coated three-dimensional fabric was evaluated mechanically and histologically in an in vivo sheep model. OBJECTIVES: To investigate the mechanical properties and the histologic appearance of the interface between the three-dimensional fabric disc and the vertebral body, and to evaluate these alterations in vivo under a spinal segmentally mobile condition. SUMMARY OF BACKGROUND DATA: Bone ingrowth to the bioceramic-coated three-dimensional fabric surface had been demonstrated already under a stable environment in preliminary animal studies. METHODS: For this study, 20 sheep underwent two-level lumbar intervertebral disc replacement with three-dimensional fabric discs (Group I) or bioceramic spacers as a comparative material (Group II). All operative segments were stabilized temporarily with spinal instrumentation for the initial ingrown phase. Four animals each were killed at 4, 6, 15, and 24 months in Group I and at 6 months in Group II, and the operative segments were subjected to either a detachment test or histologic evaluation. RESULTS: The interfacial tensile strength at 6 months was significantly higher in Group I than in Group II. No significant decrease in tensile strength was detected until 24 months after surgery in Group I. Histologically, bone ingrowth to the three-dimensional fabric surface was observed 4 months after surgery, and no aseptic loosening occurred until 24 months after surgery. CONCLUSIONS: The findings show that the three-dimensional fabric disc was firmly fixed to the vertebral body by bone ingrowth, and that this biologic fixation was preserved even under the spinal segmentally mobile condition.

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PubMed2003

Preventive effect of hyaluronic acid on the suppression of attachment and migration abilities of bovine chondrocytes by IL-1alpha in vitro.

Attachment and migration of bovine chondrocytes cultured in vitro were significantly suppressed by the addition of interleukin (IL)-1alpha at the concentration of 1 ng/ml or more (p<0.05). The application of hyaluronic acid (HA) at the concentration of 10 micro g/m l or more significantly recovered the attachment of chondrocytes (p<0.05) and the application of HA at 100 micro g/ml concentration recovered the migration of chondrocytes suppressed by IL-1alpha. These results suggest that the application of HA for inflammatory arthropathies or chondrocyte transplantation might be helpful to preserve the properties of chondrocytes and its extracellular matrix against inflammatory conditions.

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PubMed2003

Relative biological effectiveness and tolerance dose of fission neutrons in canine skin for a potential combination of neutron capture therapy and fast-neutron therapy.

To investigate the potential efficacy of fission neutrons from a fast-neutron reactor for the treatment of radioresistant tumors, the relative biological effectiveness (RBE) and tolerance dose of fission neutrons in canine skin were determined. The forelimbs of 34 healthy mongrel dogs received a single dose of fission neutrons (5.6, 6.8, 8.2, 9.6 or 11 Gy) or 137Cs gamma rays (10, 15, 20, 25 or 30 Gy). Based on observations of radiodermatitis for each radiation, the single-fraction RBE of fission neutrons in the sixth month was calculated as approximately 3. The tolerance doses of fission neutrons and gamma rays, defined as the highest doses giving no moist desquamation on the irradiated skin in the recovery phase, were estimated as 7.6 Gy and 20 Gy, respectively. The tolerance dose of 7.6 Gy of fission neutrons included 5.0 Gy of fast neutrons possessing high anti-tumor effects and 1.4 x 10(12) n/cm2 of thermal neutrons, which could be applicable to neutron capture therapy (NCT). The combination of fast-neutron therapy and NCT using a fast-neutron reactor might be useful for the treatment of radioresistant tumors.

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PubMed2002

Artificial intervertebral disc replacement using bioactive three-dimensional fabric: design, development, and preliminary animal study.

STUDY DESIGN: A new artificial intervertebral disc was developed, and its intrinsic biomechanical properties, bioactivity, and the effectiveness as a total disc replacement were evaluated in vitro and in vivo. OBJECTIVES: To introduce a new artificial intervertebral disc and to evaluate the in vitro mechanical properties, fusion capacity to bone, and segmental biomechanics in the total intervertebral disc replacement using a sheep lumbar spine. SUMMARY OF BACKGROUND DATA: The loss of biologic fusion at the bone-implant interface and prosthetic failures have been reported in previous artificial discs. There have been no clinically applicable discs with detailed experimental testing of in vivo mechanics and interface fusion capacity. METHODS: The artificial intervertebral disc consists of a triaxial three-dimensional fabric (3-DF) woven with an ultra-high molecular weight polyethylene fiber, and spray-coated bioactive ceramics on the disc surface. The arrangement of weave properties was designed to produce mechanical behavior nearly equivalent to the natural intervertebral disc. Total intervertebral disc replacement at L2-L3 and L4-L5 was performed using 3-DF disc with or without internal fixation in a sheep lumbar spine model. The segmental biomechanics and interface histology were evaluated after surgery at 4 and 6 months. RESULTS: The tensile-compressive and torsional properties of prototype 3-DF were nearly equivalent to those of human lumbar disc. The lumbar segments replaced with 3-DF disc alone showed a significant decrease of flexion-extension range of motion to 28% of control values as well as partial bony fusion at 6 months. However, the use of temporary fixation provided a nearly physiologic mobility of the spinal segment after implant removal as well as excellent bone-disc fusion at 6 months. CONCLUSION: An artificial intervertebral disc using a three-dimensional fabric demonstrated excellent in vitro and in vivo performance in both biomechanics and interface histology. There is a potential for future clinical application.

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PubMedDate not supplied

Relationship of disease progression and plasma histamine concentrations in 11 dogs with mast cell tumors.

Plasma histamine concentrations (PHCs) were measured serially over 9 months or until death in 11 dogs with mast cell tumors (MCTs). Eight dogs had grossly visible disease and the other 3 dogs had microscopic disease. Initial PHCs in the dogs with gross disease were significantly higher than PHCs in healthy dogs (median, 0.73 ng/mL and 0.19 ng/mL respectively; P < .009), whereas initial PHCs in dogs with microscopic disease showed no difference from controls. Seven dogs subsequently had progressive increases in PHC, and developed hyperhistaminemia (median, 14.0 ng/mL; range, 5.11-30.1 ng/nL). These 7 dogs died from MCTs, and 1 had general weakness with rapid lysis of a large tumor burden after radiation therapy. PHCs of the other 4 dogs were less than 1 ng/mL during the study. These 4 dogs were still alive with adequate control of the tumor at the conclusion of the study. Four of the 11 dogs initially had gastrointestinal (G1) signs, which abated soon after administration of histamine-2 (H-2) blockers. No significant difference was found between PHCs in dogs with GI signs and those without GI signs (median, 0.86 ng/mL and 0.35 ng/mL. respectively). Thereafter, 7 dogs had serious GI complications for which H-2 blocker therapy was ineffective. PHCs in these 7 dogs were extremely high (median, 12.2 ng/mL; range, 3.42-30.1 ng/nL). Results of this study demonsrated that PHC was one factor related to disease progression, and indicated that marked hyperhistaminemia was associated with the GI signs refractory to H-2 blocker therapy in dogs with MCTs.

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