Biomedical subjects

Masashi Neo

Publications and source records attributed to Masashi Neo.

23 records · Page 2Linked to original sources

PubMed2003

A comparative study between in vivo bone ingrowth and in vitro apatite formation on Na2O-CaO-SiO2 glasses.

This study compared in vivo bioactivity with the in vitro apatite-forming ability of biomaterials. Granules of five kinds of P(2)O(5)-free Na(2)O-CaO-SiO(2) glasses, showing different apatite-forming ability in simulated body fluid (SBF), were implanted into a defect on the femoral condyle of rabbits. Bone ingrowth was evaluated using scanning electron microscopy among five kinds of glasses at 1, 2, 3, 6, and 12 weeks. Quantitative analysis was performed measuring the depth of new bone ingrowth from the periphery. In addition, the total areas of newly formed bone among glass particles were examined at 3 and 6 weeks using confocal laser scanning microscopy (CLSM) after weekly administration of fluorescent calcein. The depth of bone ingrowth among glass particles increased in proportion to their apatite-forming ability in vitro. The CLSM study showed a correlation between the quantities of labeled newly formed bone and in vitro apatite-forming ability. In the P(2)O(5)-free Na(2)O-CaO-SiO(2) glasses, the periods within 3-6 days for inducing apatite in SBF considered a necessary condition to convey bioactivity in vivo, and in vivo evaluations at 2-3 weeks is important to determine this. The in vivo bioactivity was precisely reproduced by apatite-forming ability in SBF. Therefore, evaluating apatite formation in SBF is a good screening test for the in vivo bioactivity of materials, resulting in reduction of the need for animal sacrifices and savings in experimental time.

Animal Testing Alternatives↗

PubMed2003

Repair of segmental long bone defect in rabbit femur using bioactive titanium cylindrical mesh cage.

A segmental rabbit femur defect was repaired using an empty bioactive titanium (BAT) mesh cage. A 10mm long titanium mesh cage was positioned in the bony defect and reinforced by intramedullary fixation. The BAT surface was prepared by chemical and thermal treatment. Pure titanium cages were used as a control. Torsional stiffness of the BAT group at 4 weeks was approximately equal to, and at 8 weeks twice, that of the intact femur. Differences between the torsional stiffness of the control and BAT groups were significant at both time intervals. Histological examinations showed that woven bone appeared around the cage by 4 weeks and transformed to lamella bone by 8 weeks. New bone bonded to the BAT surface without an intervening layer. The BAT cage enhanced the bone repairing process and achieved faster repair of long bone segmental defects.

Animals↗

PubMed2003

Histological and mechanical investigation of the bone-bonding ability of anodically oxidized titanium in rabbits.

The purpose of this study was to histologically and mechanically investigate the in vivo bone-bonding ability of anodically oxidized titanium (AO Ti) with an anatase crystal layer on its surface. AO Ti plates, anodically oxidized at 155 V in 1 M H2SO4, were implanted into the proximal metaphyses of mature rabbit tibiae for 4, 8, 16, and 24 weeks and investigated by light microscopy, scanning electron microscopy and detaching test. High bone-bonding ability, comparable to our previous study data of the bioactive titanium produced by sodium-free alkali and heat treatment, was observed at the early stages of implantation. However, no substantial increase was demonstrated. AO Ti plates bonded to bone directly, with no intervening soft tissue layer, and no breakage of the AO Ti layer was observed. The AO Ti layer was porous through to the titanium substrate, while the porosity was low. Apatite-like deposition into the pores of the AO layer was observed only in the superficial zone. The lack of improvement of bone-bonding ability in the later stages of implantation may be attributed to the low porosity and to the superficial ingrowths of apatite-like deposits into the pores of the AO Ti layer.

Animals↗

PubMed2002

Interfacial tensile strength between polymethylmethacrylate-based bioactive bone cements and bone.

We have developed two types of polymethylmethacrylate (PMMA)-based bioactive bone cements containing bioactive glass beads (designated GBC) or apatite-wollastonite containing glass-ceramic powder (designated AWC) as the filler. A new method was used to evaluate the bone-cement interfacial strength of these bioactive bone cements. Two types of bioactive bone cements (GBC and AWC) and PMMA cement (CMW-1) were put in a frame attached to the smooth tibial metaphyseal cortex of the rabbit and polymerized in situ. The load required to detach the cement from the bone was measured at 4, 8, and 16 weeks after implantation. The interfacial tensile strength of GBC and AWC showed significantly higher values than PMMA cement from 4 weeks, and increased with time. For GBC, strength reached a maximum value of 12.39 +/- 1.79 kgf 16 weeks after implantation. Histological examination of rabbit tibiae up to 16 weeks demonstrated no intervening layer between the bioactive bone cements and the bone, whereas fibrous tissue was observed at the interface between the PMMA cement and the bone. From this study, we conclude that PMMA-based bioactive bone cements have a relatively higher adhesiveness at the interface than the conventionally used PMMA cement, showing potential as a promising alternative.

Animals↗

PubMed2002

Cervical disc herniation causing localized ipsilateral popliteal pain.

We report a patient with localized ipsilateral popliteal pain that we believe was caused by cervical disc herniation. A 52-year-old woman complained of an unusual severe aching pain in the right popliteal region. The pain increased gradually for 4 months despite the employment of conservative treatments. Eventually, the woman was unable even to stand immediately after waking because of the pain. However, physical examination of the right knee joint showed little abnormality. Although radiography of the knee joint showed slight osteoarthritic change, the pain remained unexplained. The patient also reported shoulder stiffness and slight numbness in the bilateral toes. Magnetic resonance imaging showed a large disc herniation on the right side of C3/4 and narrowing of the spinal canal at C4/5. Anterior cervical decompression and fusion surgery (C3-5) was performed to prevent impending myelopathy. After surgery the popliteal pain disappeared immediately and completely, suggesting that the cervical disc herniation had caused the pain. The pain has not recurred in almost 3 years after surgery.

Cervical Vertebrae↗