Biomedical subjects

Fuminori Kanaya

Publications and source records attributed to Fuminori Kanaya.

6 recordsLinked to original sources

PubMed2007

Biodegradation of high-toughness double network hydrogels as potential materials for artificial cartilage.

This study evaluated biodegradation properties of four novel high-toughness double network (DN) hydrogels as potential materials for artificial cartilage. Concerning each DN gel material, a total of 12 specimens were prepared, and 6 of the 12 specimens were examined to determine the mechanical properties without any treatments. The remaining 6 specimens were implanted into the subcutaneous tissue, using 6 mature female rabbits. At 6 weeks after implantation, the mechanical properties and the water content of the implanted specimens were measured. In the poly(2-acrylamide-2-methyl-propane sulfonic acid)/poly(N,N'-dimethyl acrylamide) DN gel, the ultimate stress and the tangent modulus were significantly increased from 3.10 and 0.20 MPa, respectively, to 5.40 and 0.37 MPa, respectively, with a significant reduction of the water content after implantation (94 to 91%). In the poly(2-acrylamide-2-methyl-propane sulfonic acid)/polyacrylamide DN gel and the cellulose/poly(dimethyl acrylamide) DN gel, the stress (11.4 and 1.90 MPa, respectively) and the modulus (0.30 and 1.70 MPa, respectively) or the water content rarely changed after implantation (90 and 85%, respectively). In the bacterial cellulose/gelatin DN gel, the ultimate stress was dramatically reduced from 4.30 to 1.98 MPa with a significant increase of the water content after implantation (78 to 86%). This study implied that these DN gels except for the cellulose/gelatin DN gel are potential materials that may meet the requirements of artificial cartilage.

Absorbable Implants↗

PubMed2006

Ex vivo infiltration of fibroblasts into the tendon deteriorates the mechanical properties of tendon fascicles but not those of tendon bundles.

BACKGROUND: After ligament reconstruction, mechanical deterioration of the grafted tendon is observed with revascularization and cellular infiltration. However, the effect of cellular infiltration on the mechanical properties of the tendon matrix has not been fully understood. METHODS: Cultured fibroblasts derived from the rabbit patellar tendon were seeded around an acellular rabbit patellar tendon that had undergone freeze-thaw treatment. At time-0, 3, and 6 weeks after seeding the cells, we evaluated cellular distribution in the tendon using a confocal laser microscope and the mechanical evaluations of the tendon fascicles and the tendon bundles. FINDINGS: The confocal laser microscopic analysis showed fibroblast infiltration ex vivo into the acellular tendon matrix. We could not find significant effects of the cellular infiltration on the tangent modulus of the tendon bundle, although the ex vivo cellular infiltration significantly reduced the modulus of the tendon fascicle. In addition, the tangent modulus of the incubated tendon without fibroblasts significantly decreased with time, particularly in the tendon bundle levels. INTERPRETATION: The findings of this study suggested that the effects of ex vivo cellular infiltration on the mechanical properties of the tendon bundles are relatively small, compared with its striking effect on the tendon fascicles.

Animals↗

PubMed2004

Fatal infection of the hand due to Photobacterium damsela: a case report.

We report a case of fatal acute renal failure due to Photobacterium damsela infection of the hand. Although the patient received intensive medical care and surgical treatment, he died 8 h after arrival at the hospital. This is the first case of P. damsela sepsis proven by blood culture in Japan.

Acute Kidney Injury↗

PubMed2004

Expression analyses of human endogenous retroviruses (HERVs): tissue-specific and developmental stage-dependent expression of HERVs.

The evolutional and biological roles of human endogenous retroviruses (HERVs) are less recognized compared to those of L1. In the present study, we focused on the transcriptional activity of HERVs in normal human tissues and found five HERV loci that are actively expressed in normal tissues. All but one showed tissue specificity of expression: one was expressed in stomach and small intestine and three were in placenta. We subsequently examined by TaqMan-based RT-PCR assays the temporal expression profiles of the three placenta-specific HERVs along with syncytin and syncytin 2 and observed three patterns. Syncytin and HERV-Fb showed almost constant expression through gestations. Syncytin 2 gradually decreased as pregnancy proceeded. In contrast, expression from the HERV-H/F and HERV-K(HML-6) loci increased remarkably in term placentas. Term placentas in general showed larger interindividual differences in HERV expression levels. Our results suggest that HERVs might have more diverse effects than currently thought.

Databases, Genetic↗

PubMed2004

Biomechanical study of adjacent intervertebral motion after lumbar spinal fusion and flexible stabilization using polyethylene-terephthalate bands.

Thirty fresh-frozen calf cadaveric spinal specimens (L3-L6) were used to investigate the effect of flexible stabilization and fixation on the adjacent intervertebral motion segment. The intact spine that had not been subjected to injury was used for comparison as control. The destabilized spine was made up of specimens from which the bilateral facet joints and the supraspinous and interspinous ligaments were removed. The flexible stabilized spine was applied with pedicle screws and polyethylene-terephthalate bands, and the fixed spine was applied with pedicle screws and rods at the L4-L5 segment. The range of motion (ROM) was measured under flexion, extension, and bilateral bending moments, and the ROM ratio (ROM of each model versus ROM of the comparison model) was calculated at L3-L4, L4-L5, and L5-L6 segments. In the flexible stabilized spine, the restriction of motion was high under flexion and bilateral bending moments, and the mobility of the adjacent intervertebral motion segments approximated the normal lumbar vertebra. In the fixed spine, the ROM ratio increased at the cranial and caudal adjacent segments.

Biomechanical Phenomena↗

PubMed2002

Mixed nerve suture facilitated by enzyme-staining techniques.

Identification of motor and sensory fascicles to correctly match the motor and sensory fascicles helps surgeons to correctly align nerve stumps. Motor fibers, with their high cholinesterase activity, can be differentiated from sensory fibers. I developed a new modification that requires less than 1 hour and shows clearer differentiation compared with other histochemical techniques. In my clinical research, proximal stumps can be stained as long as 16 months after injury, however, distal stumps cannot be stained after 5 days. After 5 days, this staining could provide useful proximal information and distal fascicles may be identified by anatomic or topographical knowledge. I think this staining is especially useful in proximal nerve lesions and nerve injuries that require nerve graft within 4 days after injury. Also, this technique is useful in functioning muscle transfer to find motor fascicles and, in a sensate flap, to identify the sensory fascicle.

Journal Article↗