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Biomedical subjects

T Yamamuro

Publications and source records attributed to T Yamamuro.

At least 55 records · Page 3Linked to original sources
PubMed1994

Osteoclastic resorption of apatite formed on apatite- and wollastonite-containing glass-ceramic by a simulated body fluid.

We immersed mirror-polished apatite- and wollastonite-containing glass-ceramic (A-W GC) disks in a simulated body fluid (SBF) for 5 days to form bonelike apatite on their surface. Neonatal rabbit bone cells were cultured on these or on plain A-W GC disks for 10, 24, and 48 h. We observed the substrates by scanning electron microscopy after treating them with pronase E plus EDTA to remove all cells except osteoclasts. Osteoclasts with a non-motile appearance formed no lacunae on the plain A-W GC, whereas on the bonelike apatite formed on A-W GC by the SBF, actively moving osteoclasts made many tracklike resorption lacunae. These were evident even after 10 h of culture and became more extensive after longer culture periods. The bonelike apatite was therefore a more suitable medium than plain A-W GC for maintaining osteoclast activity. This study demonstrated in vitro osteoclastic resorption of bonelike apatite formed on A-W GC by an SBF. It suggests that the apatite layer, through which a surface-active ceramic bonds to bone in vivo, can be resorbed by osteoclasts and subjected to bone remodeling.

Animals↗
PubMed1994

Calcium-dependent neutral proteinase (calpain) in fracture healing in rats.

Calpain refers to Ca(2+)-dependent neutral cysteine proteinase, which originally was thought to be an intracellular proteinase but recently has been shown to function extracellularly as well. This report describes the immunohistochemical demonstration of calpain and biochemical changes in the amount of calpain during fracture healing in rats. The tibiae of 6-week-old Wistar rats were fractured, and calluses were obtained 5-28 days after fracture. A frozen section of the fracture callus was stained by the immunoperoxidase method with use of polyclonal antibodies of calpains I and II. Positive staining was noted with the anti-calpain II antibody in the perivascular areas, chondrocytes, and cartilage matrix in calluses at 5, 7, and 10 days. Less intense staining was seen in older calluses. The caseinolytic activity of calpain II reached its maximum on the 5th day, was high on the 7th and 10th days, and decreased rapidly thereafter. The quantity of calpain II was dependent on the process of fracture healing. It was concluded that calpain was working as one of the matrix proteinases in fracture callus.

Animals↗
PubMed1994

Flexor tendon growth in chickens.

We investigated the longitudinal growth of the flexor tendon in detail by marking tendons along their lengths in young chickens, using a microsurgical technique, and observing the separation of the marks at various times during tendon growth to establish normative standardized data on the longitudinal growth of flexor tendons. The interstitium throughout the entire tendon was found to increase in length, although the growth at the insertion zone was less marked than that in other areas. To determine the relationship between the growth of the tendon and the growth of the underlying bone, the lengths of the phalanges and metatarsus were measured. The distance from the insertion to the bifurcation of the tendon and the distance from the bifurcation to the most distal point of the musculotendinous junction also were measured. The findings suggest that the growth of tendon is proportionate to the growth of underlying bone. Tendon growth at the musculotendinous junction was studied in further detail, and no significant difference was found between growth at the most proximal zone of the tendon and growth at the zone within the musculotendinous junction.

Animals↗
PubMed1994

Effect of sterilization on bone morphogenetic protein.

Demineralized bone matrix and bone morphogenetic protein have been used clinically to accelerate bone regeneration. However, the best method of sterilization has been the subject of controversy. Some investigators have used ethylene oxide, but others have reported that doses adequate for sterilization destroyed the osteoinductivity of demineralized bone matrix and that gamma irradiation was less harmful in this respect. We used partially purified bone morphogenetic protein and type-I collagen to investigate the effects of sterilization by ethylene oxide and gamma irradiation on the activity of bone morphogenetic protein. Osteoinductivity was reduced considerably after sterilization by gamma irradiation at 2.5 Mrad and by ethylene oxide at 37 degrees C for 4 hours and at 55 degrees C for 1 hour; however, the reduction induced by ethylene oxide at 29 degrees C for 5 hours was about half of the control values. This study showed that ethylene oxide at 29 degrees C for 5 hours can be used clinically for sterilization of bone morphogenetic protein. We also investigated the effect of gamma irradiation on bone morphogenetic protein and the collagen carrier separately and found that collagen was far more labile than bone morphogenetic protein.

Animals↗
PubMed1994

Bioabsorbable osteosynthetic implants of ultra high strength poly-L-lactide. A clinical study.

We have developed reasonably strong but bioabsorbable osteosynthetic screws, pins and nails made of ultra high strength poly-L-lactide (PLLA) and evaluated their use in 143 patients. The PLLA implants have the highest strength among those reported to date. They lose about 10% of their initial strength within 8 weeks, about 40% within 4 weeks and nearly 100% within 20 weeks in vivo. The patients were aged from 9 to 78 years, and the follow up was from 2 to 6 years. The implants were used for fixation of bone grafts in 84 patients, peri- and intra-articular fractures in 49, after osteotomy in 8, and in 2 others. Bony union was not achieved in only one case. In the early stages of the study, breakage of screws occurred in 12 cases (8%), mostly because of an inappropriate size of tap; these problems have not occurred after improvement of the tapping system. There were no cases with abnormal blood tests, infection or foreign body reaction.

Adolescent↗
PubMed1994

Solitary muscular sarcoidosis: CT, MRI, and scintigraphic characteristics.

Scintigraphy using gallium-67 (67Ga) citrate and penvaralent technetium-99m dimercaptosuccinic acid ([99mTc(V)]DMSA) and other radiological examinations were performed in three patients with solitary muscular sarcoidosis who had tumor-like muscular lesions. Although distinction from other invasive soft tissue tumors was difficult using plain and enhanced computed tomography and magnetic resonance imaging, marked uptake of 67Ga and moderate uptake of [99mTc(V)]DMSA were shown at the sites of granulomatous inflammatory lesions of sarcoidosis. Both 67Ga and [99mTc(V)]DMSA scintigraphy could be of value in the diagnosis and detection of distribution of granulomas of sarcoidosis in the soft tissue and in determining the appropriate region for biopsy.

Adult↗
PubMed1994

Modification of strain-specific femoral bone density by bone marrow-derived factors administered neonatally: a study on the spontaneously osteoporotic mouse, SAMP6.

SAMP6 is a recently developed strain of osteoporotic mice, and SAMP2 is a control for SAMP6 and has a higher peak bone mass. The bone mass of SAMP6 was increased until 2 months of age when a lysate of cells derived from the bone marrow of SAMP2 was injected at 1 or 4 days of age, but it was not increased when the lysate was injected at 21 days of age. No effect on bone mass was observed when lysates of other cells, bovine serum albumin or heat-inactivated lysate of bone marrow-derived cells of SAMP2, were injected. The ability to increase bone mass was not in the supernatant but in the pellet obtained by ultracentrifugation (105,000 g) of the lysate of bone marrow-derived cells of SAMP2. The lysate did not change the osteoclast surface but changed the appositional bone formation. In conclusion, the lysate of cells derived from the bone marrow of SAMP2 contains factors which can increase the bone mass of SAMP6, and these factors are present in the pellet obtained by ultracentrifugation.

Animals↗
PubMed1994

Symptomatic type D (separated) medial plica: clinical features and surgical results.

The clinical presentation and results of surgery in 20 cases of symptomatic type D (separated) medial plica were reviewed. The group was composed of cases with a fenestration (14 knees), reduplication (two knees), and tear (four knees). Based on preoperative symptoms and clinical presentation, the patients were divided into two groups: the first group had symptoms localized to the medial compartment (11 knees), and the second group had symptoms and/or signs in the patellofemoral joint and/or lateral compartment (nine knees). The symptoms of the second group mimicked those of lateral meniscal tear or patella subluxation, and no definite preoperative diagnosis was possible. Two patients showed difficulty of full extension "active extension test." Excellent or good results were obtained with surgery in all patients after an average follow-up of 39 months. Although resection of the type D medial plica resulted in a favorable outcome, special attention should be made in preoperative diagnosis of this type of plicae.

Adolescent↗
PubMed1994

Soft-tissue tumors: diagnosis with Tc-99m (V) dimercaptosuccinic acid scintigraphy.

PURPOSE: To assess the potential of technetium-99m (V) dimercaptosuccinic acid (DMSA) scintigraphy for diagnosis of soft-tissue tumors. MATERIALS AND METHODS: Tc-99m (V) DMSA scintigraphy was performed in 76 patients with histologic proof of soft-tissue tumors. In 57 of these patients, gallium-67 citrate scintigraphy was performed within 2 weeks after Tc-99m (V) DMSA scintigraphy. RESULTS: Uptake of Tc-99m (V) DMSA was clearly detected in almost all sarcomas, metastatic carcinomas, highly recurrent benign tumors (ie, extra-abdominal desmoids and tenosynovial giant cell tumors), superficial and deep hemangiomas, and granulomatous soft-tissue lesions but was not found in other benign solid tumors of soft tissue. Uptake of Ga-67 citrate was clearly detected in all inflammatory lesions and metastatic carcinomas, eight of 14 sarcomas (57%), and two of 10 highly recurrent benign tumors (20%) but was not found in hemangiomas or benign soft-tissue tumors. CONCLUSION: Low-grade malignant and highly recurrent benign lesions, which often recur after surgery, were detected more accurately with Tc-99m (V) DMSA scintigraphy than with Ga-67 citrate scintigraphy.

Adolescent↗
PubMed1994

Case report: uptake of pentavalent technetium-99m dimercaptosuccinic acid by pigmented villonodular synovitis: comparison with computed tomography, magnetic resonance imaging and gallium-67 scintigraphy.

The scintigraphic findings of a patient with pigmented villonodular synovitis are described and compared with the computed tomography and magnetic resonance imaging data. Intense uptake of pentavalent technetium-99m dimercaptosuccinic acid without gallium-67 citrate uptake indicates that pigmented villonodular synovitis has the features of a hyperplastic or neoplastic lesion rather than an inflammatory lesion from the point of view of nuclear medicine.

Adult↗
PubMed1994

Long-term changes in the haversian systems following high-dose irradiation. An ultrastructural and quantitative histomorphological study.

The effects of high-dose irradiation on the morphology of haversian bone were studied, over a fifty-two-week period, in seventy-seven adult rabbits, after the administration of a single dose of radiation (therapeutic x-ray; twenty-five, fifty, or 100 gray) to one knee joint. The specimens of bone were examined with microangiography, light and transmission electron microscopy, and histomorphometry. Analysis was performed on the haversian bone in the subchondral bone plate of weight-bearing portions of the femoral condyles. Microangiography demonstrated dilatation of the microvasculature four weeks after irradiation. Beginning at twelve weeks, there was a marked decrease in vascularity; no obvious recovery of the subchondral bone had occurred by fifty-two weeks. At four weeks, morphological analysis revealed two changes in the haversian canals: simple occlusion of the haversian vessels with loss of cells in the canal, and dilatation of the capillaries with abnormal resorption of the perivascular bone matrix by osteoclasts. The abnormal bone resorption was not coupled with subsequent new-bone formation, resulting in increased porosity. Beginning at four weeks, a progressive decrease in the number of haversian vessels and in cellularity became prominent. The decrease in cellularity involved all types of cells, including endothelial cells, pericytes, perivascular mesenchymal cells, osteoblasts, osteocytes, and osteoclasts. The loss of perivascular cells was often but not always associated with occlusion of the haversian vessels. Histomorphometry revealed both time-dependent and dose-dependent decreases in capillary density (the number of intraosseous capillaries per unit area) and in the number of osteocytes in the subchondral bone plate. The porosity of the same areas showed a significant increase by four weeks (p < 0.001 after administration of twenty-five gray and p < 0.01 after administration of both fifty and 100 gray), but between twelve and fifty-two weeks, there was only a slight additional increase. Statistical analysis revealed significant correlations between capillary density and osteocyte survival (p < 0.001) and between capillary density and porosity (p < 0.001). The portion of the subchondral bone plate that was located farthest from the non-irradiated normal bone showed progressive damage and no sign of recovery at fifty-two weeks.

Animals↗
PubMed1994

Gait after knee arthroplasty for femoral tumor. Foot pressure patterns recorded in 20 patients.

We evaluated pressure distribution patterns under the feet during gait in 20 patients after resection of malignant bone tumor and endoprosthetic replacement of the distal femur. In all cases, a modular cementless, hinged prosthesis had been used. The examination was performed after 4 (1-6) years. Shortened contact phase, decreased peak pressure, and reduced force-time integral during gait analysis were observed on the operated side. Peak pressure in the heel and the toe regions was decreased and the load (force-time integral) in the metatarsal heads and the big toe regions was reduced. There was a positive correlation between load under the foot and knee extension strength, measured isokinetically.

Adolescent↗
PubMed1994

Metallosis due to abnormal abrasion of the femoral head in bipolar hip prosthesis. Implant retrieval and analysis in six cases.

We report on six cases of metallosis which developed in bipolar hip prosthesis due to ceramic screws used for fixation of bone grafts. Two patients experienced severe metallosis due to abnormal abrasion of the femoral head. At the revision surgery, proliferated black synovia was found. Analyses of the retrieved prostheses revealed numerous small particles of alumina ceramic on the inner surface of the bearing insert of UHMWPE. These particles came from the broken ceramic screws, and scraped away the metallic femoral head resulting in severe metallosis. In four patients, the outer head came into direct contact with ceramic screws and mild metallosis was observed at revision surgery.

Adult↗
PubMed1994

Tendon growth in rabbits.

The longitudinal growth of the Achilles and tibialis anterior tendons in young rabbits was investigated. At 5 weeks of age, sutured marks were placed along the entire length of each tendon from the musculotendinous junction to the portion near the osseous attachment using a microsurgical technique. The distances between the marks were measured using a microscope with a micro ruler. At 16 weeks of age, all distances between the marks had increased. In the Achilles tendon, none of the intermark distances differed significantly. In the tibialis anterior, the retinaculum is situated between the musculotendinous junction and the insertion, and acts as a pulley, so this tendon was divided into 2 zones, one proximal and one distal to the retinaculum, and the intermark distances were measured. There were no significant differences among these distances in proximal, or distal zones, but those in the proximal zone were greater than those in the distal zone (< 0.01). Furthermore, in a separate experiment, the longitudinal growth of the underlying bone in the zone proximal to the retinaculum was found to be greater than that in the distal zone (p < 0.01).

Achilles Tendon↗
PubMed1994

Changes in joint fluid after total arthroplasty. A quantitative study on the rabbit knee joint.

Quantitative and time dependent changes in joint fluid after total arthroplasty were investigated by applying a new dilution method to a rabbit model of total knee replacement. The joint fluid volume and total protein concentration had increased by 2 weeks after arthroplasty, reached their maximum values at 4 weeks, and decreased by 12 weeks when they were similar to the control levels. The hyaluronic acid concentration and its mean molecular weight however, were lowest 2 weeks after operation and gradually increased by 12 weeks, although the recovery was then still incomplete. Histological examination of the newly formed capsular tissues revealed both acute and chronic inflammations, the latter including granulomatous reactions to polyethylene wear particles. These results provide fundamental information not only on the biological response of periarticular tissues to total arthroplasty but also on the friction, lubrication, and wear of prosthetic joints.

Animals↗
PubMed1994

Schwannoma of the extremities: comparison of MRI and pentavalent technetium-99m-dimercaptosuccinic acid and gallium-67-citrate scintigraphy.

The diagnostic value of MRI and scintigraphy was studied in patients with Schwannomas of the upper or lower extremities. MRI (T1- and T2-weighted imaging), pentavalent 99mTc-dimercaptosuccinic acid and 67Ga-citrate scintigraphy were performed in 11 patients with 12 histologically proven benign Schwannomas. All six tumors with a maximum diameter > or = 3 cm showed marked accumulation of pentavalent 99mTc-dimercaptosuccinic acid, whereas they showed no uptake of 67Ga-citrate. MRI detected all of the tumors, and the lesions had a signal intensity equal to or slightly less than that of skeletal muscle on T1-weighted images and hyperintense to that of subcutaneous fat on T2-weighted images. MRI was superior to detect small Schwannomas of the extremities. A positive 99mTc-dimercaptosuccinic acid scan and a negative 67Ga-citrate scan however is useful to distinguish sarcoma with myxoid change from Schwannoma.

Adolescent↗
PubMed1994

[Clinical application of AW glass ceramic prosthesis in spinal surgery].

Bone prosthesis of apatite- and wollastonite-containing glass-ceramic (AW-GC), a new synthesized material, is known to be excellent in bonding directly with adjacent living bone tissue, in having strong mechanical strength and no toxic effects, in experimental studies. In spinal surgery, massive and strong bone grafts are required for reconstruction of the spinal column affected by a tumor, trauma, or a degenerative disease. However, utilization of bone allograft is not yet socially accepted in Japan and also there are other barriers against the supply of allograft bone. In the present study, AW-GC bone prosthesis was used for reconstructive surgery for various spinal diseases and follow-up studies were performed for an average of 14.9 months (range: 2-36 mo). The clinical results were satisfactory. Thirty patients (males: 17 and females: 13) with an age range of 40-75 years (mean: 55.3 years) were reviewed in this study. Preoperative diagnoses for which an AW-GC prosthesis was required were as follows; vertebral prosthesis: 15 with metastatic tumor of the spine, 3 with burst fracture of the thoraco-lumbar spine; vertebral spacer: 6 with degenerative spondylolisthesis, 2 with isthmic spondylolisthesis, 2 with lumbar intervertebral disc herniation, and one with spinal canal stenosis. Patient's satisfaction, roentgenographic evaluation, laboratory data on blood and urine, and toxic effects were examined in these patients. As a result, the patient's satisfaction for the AW-GC bone prosthesis was high, and the initial fixation and long term stability were excellent. For kyphotic deformity and scoliosis, postoperative correction could be maintained in two patients where correction was attempted, and the usefulness of AW-GC prosthesis as a spinal prosthesis was confirmed. Good bone formation around the prosthesis was observed with time. The clear zone (radiolucent line between ceramic and bone) tended to decrease or disappear. There were no systemic or local toxic side-effects considered to be due to the AW-GC bone prosthesis, or no abnormalities in the laboratory data. These findings suggested that the AW-GC bone prosthesis is a new biomaterial with excellent properties which can be successfully substituted for bone graft in reconstructive spinal surgery.

Adult↗