Biomedical subjects

Masaru Murata

Publications and source records attributed to Masaru Murata.

4 recordsLinked to original sources

PubMed2006

Biodegradation and bioabsorption innovation of the functionally graded bovine bone-originated apatite with blood permeability.

Bioabsorbable and functionally graded apatite (fg-HAp) ceramics were designed using bovine bone by the calcination and partial dissolution-precipitation methods. The fg-HAp ceramics that were developed had gradual distributions of the degree of crystallinity and the grain size of single-phase hydroxyapatite from the surface layer of the pore wall to the bulk structure region. Calcination at 1073 K gave a specific surface area of 30 m2 x g-1 and porosities of 60-80%. The pore structure of the fg-HAp was classified into two regions: a macro-pore region (100-600 microm) originating from spongy bone and a micro-pore region (10-160 nm) related to body fluid permeation and blood permeability. By implantation in subcutaneous tissue of rat, it was confirmed that body fluid permeated the bulk region of the fg-HAp ceramics through the micro-pores. The volumetric populations occupied by body fluid were 60% at 4 weeks and 68% at 8 weeks in the ceramics explants, indicating drastic bioabsorption, although the body fluid was found to be immunopositive for an albumin as the main serum protein in blood. On the fg-HAp ceramics developed here, the bioabsorption rate could be controlled by careful selection of the calcination temperature. These ceramics can be applied as new biomimetic ceramics exhibiting surface and bulk degradations and cellular absorption by giant cells.

Adsorption↗

PubMed2004

Comparison of maxillary canine retraction with sliding mechanics and a retraction spring: a three-dimensional analysis based on a midpalatal orthodontic implant.

The purpose of this study was to compare maxillary canine retraction with sliding mechanics and a Ricketts canine retraction spring, using a midpalatal orthodontic implant as a measuring reference. Eight patients (three males and five females) were examined. Because maximum posterior anchorage was required in all subjects, osseointegrated midpalatal implants were used. To examine tooth movement, impressions of the maxillary arch were made at each appointment and cast in die stone. A three dimensional (3D) surface-scanning system using a slit laser beam was used to measure the series of dental casts. The results demonstrated that 3D analysis of tooth movement based on a midpalatal orthodontic implant provided detailed information on canine retraction. The results also suggested that a canine retracting force of 1 N or less was more effective not only for sliding mechanics but also for the retraction spring. However, the sliding mechanics approach was superior to the retraction spring with regard to rotational control.

Adult↗

PubMed2003

Bone augmentation using rhGDF-5-collagen composite.

The aim of this study was to evaluate the effectiveness of local application of growth differentiation factor-5 (GDF-5)-collagen composite on bone augmentation on the rat calvaria. GDF-5-collagen composite is made from recombinant human GDF-5 (rhGDF-5) and purified bovine type I atelocollagen. The GDF-5 solution was mixed with 0.3% atelocollagen acid solution, and the mixture was lyophilized. The spongy lyophilized material was pressed into the shape of a minidisk to make the GDF-5-collagen composite. The GDF-5-collagen composite contained 1, 10, or 100-microg rhGDF-5. The control collagen composite contained 0-microg rhGDF-5. The GDF-5-collagen composite or control collagen composite was inserted beneath the calvarial periosteum of 4-week-old rats. At 3 weeks after implantation, the implants containing 1-microg rhGDF-5 had mostly induced new bone formation on the cranial side. In the implants containing 10- microg rhGDF-5, bone formation had proceeded to the center of the GDF-5-collagen composite from the periosteal and the cranial sides, and bone marrow was seen focally. The augmented bone showed a connected trabecular structure with abundant vascularization. The implants containing 100-microg rhGDF-5 were nearly entirely replaced by new bone with bone marrow, and the augmented bone was firmly connected with the original bone. Neither cartilage nor bone formation was found in the control collagen composite. Thus, we conclude that the GDF-5-collagen composite may be a superior biomaterial for bone augmentation and this composite could be useful as a local osteoinductive device.

Animals↗

PubMed2001

Combined hepatocellular/cholangiocellular carcinoma with sarcomatoid features: genetic analysis for histogenesis.

The histogenesis of sarcomatoid transformation in hepatocellular carcinomas (HCCs) and cholangiocellular carcinomas (CCCs) remains unclear. In the current case, microsatellite loss of heterozygosity (LOH) assay and mutational analysis of the p53 gene with immunohistochemical examination were performed to investigate the histogenesis of each component. The tumor was composed of two parts: one part comprised poorly differentiated HCC (HCC portion), while the other part included undifferentiated, sarcomatoid HCC and CCC (combined portion). LOH at D8S555 was detected in both portions. 1-bp cytosine was deleted at codon 241 of exon 7 of the p53 gene in the combined portion. Immunohistochemically, p53 accumulated in the nuclei of undifferentiated, sarcomatoid HCC and CCC cells, suggesting that the p53 gene mutation might be common in these components. These results support the hypothesis that undifferentiated, sarcomatoid HCC and CCC could be offspring from the original HCC.

Journal Article↗