Biomedical subjects

T Yamamuro

Publications and source records attributed to T Yamamuro.

At least 19 recordsLinked to original sources

PubMed1992

The effect of active vitamin D3 analogs and dexamethasone on the expression of osteocalcin gene in rat tibiae in vivo.

We tested the effects of 1 alpha,25-dihydroxyvitamin D3 (1,25-(OH)2D3), 2 beta-(3-hydroxypropoxy)-1 alpha,25-dihydroxyvitamin D3 (ED-71) and dexamethasone on osteocalcin mRNA levels in rat tibiae in vivo. Northern blot analysis showed that both 1,25-(OH)2D3 and ED-71 caused an increase in osteocalcin mRNA levels in bone: 1,25-(OH)2D3 induced a transient increase in the mRNA levels followed by a decrease in the control level by 12 h post administration. In contrast, ED-71 caused a persistent increase in osteocalcin mRNA level for seven days post administration. Serum osteocalcin levels paralleled the osteocalcin mRNA level in bone in both groups. Dexamethasone caused a marked reduction in both osteocalcin mRNA and serum osteocalcin levels. Suppressive effect of dexamethasone on osteocalcin expression was persistent for seven days at higher dose. Our results represent the first demonstration of the effect of active vitamin D and corticosteroid on the expression of osteocalcin mRNA in bone in vivo.

Amino Acid Isomerases↗

PubMed1992

Mutation spectrum of the p53 gene in bone and soft tissue sarcomas.

We present here an analysis of the spectrum of mutations of the p53 gene seen in 127 bone and soft tissue sarcomas of various histological classifications. Gross rearrangements were analyzed by Southern blotting using a complementary DNA probe from the p53 gene, and subtle alterations in the entire coding sequence (exons 2 through 11) were identified by a combination of single-strand conformation polymorphism analysis and direct genomic sequencing. A total of 42 somatic alterations of the p53 gene were found, of which 21 were gross rearrangements and 21 were subtle alterations. These included 17 cases of a single base substitution, 3 small deletions, and one single base insertion. In contrast to reported findings for other types of cancer, we found that mutations of the p53 gene in sarcomas are quite heterogeneous both in their distribution throughout the gene and in the type of genetic alterations that result. All 13 missense mutations we found occurred at highly conserved residues, whereas 8 nonsense mutations occurred at sites that spanned the gene from codons 46 to 316. Surprisingly, approximately one-half of the osteosarcomas with allelic deletions on 17p did not have detectable alterations in the coding sequence of the p53 gene.

Alleles↗

PubMed1992

Heterotopic bone formation induced by bone morphogenetic protein in mice with collagen-induced arthritis.

A study was conducted to investigate the influence of systemic inflammation on heterotopic bone formation induced by bone morphogenetic protein (BMP). Five-milligram pellets of BMP were implanted in mice with type II collagen-induced arthritis. Intraperitoneal injections of interleukin-1 (IL-1) were also administered to a group of mice without collagen-induced arthritis. The amount of BMP-induced heterotopic bone formation was evaluated by soft X-ray radiography, histology, and assay of calcium content. BMP-induced heterotopic bone formation was markedly enhanced in mice with collagen-induced arthritis, and also in IL-1-treated mice. These findings suggest that bone formation is enhanced in mice with collagen-induced arthritis, and that IL-1 may be responsible.

Animals↗

PubMed1992

Immunohistochemical study of bone GLA protein in primary bone tumors.

METHODS: The immunoreactivity of bone GLA protein (BGP) in primary bone tumors, including osteosarcoma, chondrosarcoma, malignant fibrous histiocytoma of bone (MFH), and giant cell tumor of bone (GCT), was investigated with anti-BGP rabbit serum and peroxidase-antiperoxidase complex. RESULTS: As to intracellular localization, BGP antigenicity was detected in 33 of 35 cases of osteosarcoma and 12 of 25 cases of chondrosarcoma. However, there were no positive findings in all 15 cases of MFH or 20 cases of GCT. In chondrosarcoma, the frequency of positively stained cases increased according to pathologic grading (i.e., 3 of 14 cases of Grade 1, 7 of 9 cases of Grade 2, and 2 of 2 cases of Grade 3). Although the multinucleated cells in MFH or GCT were not immunostained, BGP antigenicity was observed in the multinucleated cells of osteosarcoma (12 of 15 cases). In the matrix of osteosarcoma, BGP immunoreactivity of the tumorous osteoid was observed in 28 of 32 cases. However, in the matrices of chondrosarcoma, MFH, and GCT, BGP immunoreactivity was not observed. CONCLUSION: These results suggest that the immunohistochemical study of BGP is useful for the differential diagnosis of bone tumors.

Bone Neoplasms↗

PubMed1992

Characterization of proteoglycan degradation by calpain.

Degradation of cartilage proteoglycans was investigated under neutral conditions (pH 7.5) by using pig kidney calpain II (EC 3.4.22.17; Ca(2+)-dependent cysteine proteinase). Aggregate and monomer degradation reached a maximum in 5 min at 30 degrees C when the substrate/enzyme ratio was less than 1000:1. The mode of degradation was limited proteolysis of the core protein; the size of the products was larger than that of papain-digested products and comparable with that of trypsin-digested products. The hyaluronic acid-binding region was lost from the major glycosaminoglycan-bearing region after incubation with calpain II. Calpains thus may affect the form of proteoglycans in connective tissue. Ca(2+)-dependent proteoglycan degradation was unique in that proteoglycans adsorb large amounts of Ca2+ ions rapidly before activation of calpain II: 1 mg of pig cartilage proteoglycan monomer adsorbed 1.3-1.6 mu equiv. of Ca2+ ions before activation of calpain II, which corresponds to half the sum of anion groups in glycosaminoglycan side chains. This adsorption of Ca2+ was lost after solvolysis of proteoglycan monomer with methanol/50 mM-HCl, which was used to desulphate glycosaminoglycans. Therefore cartilage proteoglycans are not merely the substrates of proteolysis, but they may regulate the activation of Ca(2+)-dependent enzymes including calpains through tight chelation of Ca2+ ions between glycosaminoglycan side chains.

Animals↗

PubMed1992

Prevalence and spectrum of germline mutations of the p53 gene among patients with sarcoma.

BACKGROUND: Recent studies have identified germline mutations of the p53 tumor-suppressor gene in families with the Li-Fraumeni syndrome, a rare inherited disorder characterized by a high risk of sarcomas of bone and soft tissue, breast cancer, and other tumors. In this report, we address the possibility that some sporadic sarcomas may be associated with new germline mutations of the p53 gene, which would not be manifested as familial cancer unless the patient survived to reproduce. METHODS: We studied DNA from peripheral leukocytes of 196 patients with sarcoma and from 200 controls. Of the 196 patients with sarcoma, 15 were selected because they had had multiple primary cancers or had a family history of cancer. The entire coding sequence and splice junctions of the p53 gene were analyzed for mutations. RESULTS: Eight germline mutations were found, three in patients with no known family history of cancer and five in patients with an unusual personal or family history of cancer. Four mutations caused amino acid substitutions, and four caused stop codons. These mutations were not present in any of the 200 controls. CONCLUSIONS: New germline mutations of the p53 gene are rare among patients with "sporadic" sarcoma but may be common in patients with sarcoma whose background includes either multiple primary cancers or a family history of cancer. Diverse mutations of this gene were associated with an increased likelihood of cancer; hence, the entire gene should be considered a target for heritable mutation. It appears that the group of patients with cancer who carry germline mutations of the p53 gene is more diverse than is suggested by the clinical definition of the Li-Fraumeni syndrome. The identification of carriers could be of substantial clinical importance.

Adolescent↗

PubMed1992

Allelotype analysis in osteosarcomas: frequent allele loss on 3q, 13q, 17p, and 18q.

We have investigated the involvement of tumor suppressor genes in the genesis of osteosarcoma by analyzing allele losses at polymorphic loci in tumor tissues. Genotypes of DNA from primary osteosarcoma tissue and corresponding normal cells from 37 patients were analyzed at 58 polymorphic loci representing each autosomal chromosome arm except 5p and 20q. Allele losses were found at polymorphic loci on 36 of 37 chromosome arms analyzed. In particular, four of them showed frequencies of allele loss higher than 60%: 3q (75%); 13q (68%); 17p (72%); and 18q (64%). This result suggests that, in addition to the RB (retinoblastoma) gene on 13q and the p53 gene on 17p, at least two more tumor suppressor genes located on 3q and 18q are frequently involved in the development of osteosarcoma. The extent of allele losses as defined by fractional allelic loss among 36 tumors was diverse, from 0 to 0.64. The median fractional allelic loss value of 0.32 was much higher than those previously reported in colorectal carcinoma and breast carcinoma. Although no definite association of fractional allelic loss value to clinical prognosis of each case was found in osteosarcoma, tumors with 17p loss were more prone to the early onset of lung metastasis than tumors without 17p loss, indicating that allele loss on chromosome 17p can be a useful measure of prognosis.

Adolescent↗

PubMed1992

Calcium-dependent cysteine proteinase (calpain) in human arthritic synovial joints.

OBJECTIVE: To study the roles of calpains in the synovial joint in rheumatoid arthritis (RA) and osteoarthritis (OA) and to verify the hypothesis that calpains present in the synovial fluid come from the synovium. METHODS: We performed immunohistochemical, biochemical, and immunoblotting analyses for calpains in synovial tissues, synovial cell cultures, and synovial fluids. RESULTS: Immunohistochemical staining of RA synovium demonstrated specific cytoplasmic staining of cells in the synovial lining layer, storomal fibroblasts, and endothelial cells. OA synovium showed almost the same intensity and distribution of calpain staining. DEAE-cellulose chromatography of RA and OA synovial extracts and synovial fluids showed a peak of caseinolytic activity attributable to calpain, as well as an inhibitory peak of calpastatin, a specific inhibitor protein of calpains. Immunoblotting using the anticalpain antibody from the calpain peak of RA and OA synovium and synovial fluid showed identity with the heavy subunit of calpain (80 kd). Similarly, calpain existed in the same form (80 kd) in conditioned media (supernatant) obtained from synovial cell cultures, as well as in the synoviocytes. The total specific activity of the 2 calpains in the synovial fluid of RA patients was higher than that of calpastatin. CONCLUSION: The findings suggest that the extracellular appearance of calpains could be due to the secretion of these proteins from the synovial cells and that calpains may play a role in cartilage damage of RA and OA that occurs in synovial joints.

Arthritis↗

PubMed1992

Metabolic bone disease following gastrectomy: assessment by dual energy X-ray absorptiometry.

Although disorders in bone metabolism have long been recognized as typical sequelae of gastrectomy, there has until now been no reliable method of providing precise assessment of bone mass, resulting in a variation of reported incidence. In this study, metabolic bone disease was evaluated in a well characterized population: 34 men 2-5 years after gastrectomy; 11 men 6-10 years after gastrectomy; eight men 2-5 years after colonic resection; and 115 healthy men. The age range was 50-69 years. An innovative reliable method of dual energy X-ray absorptiometry was used which allows quantitative assessment of bone mineral content. Measurement of lumbar spine bone mineral density revealed that the mean(s.e.m.) bone mineral density in patients who had had a gastrectomy (2-5 years 0.84(0.03) g/cm2, 6-10 years 0.85(0.05) g/cm2) was significantly lower than that of patients who had undergone colonic resection (0.96(0.04) g/cm2) or healthy men (0.96(0.03) g/cm2). This study demonstrates that a high incidence of bone atrophy is induced at the relatively early period of 2-5 years after gastrectomy.

Absorptiometry, Photon↗

PubMed1992

Acute nephrotoxicity as an adverse effect after intraperitoneal injection of massive amounts of bioactive ceramic powders in mice and rats.

Silicon elution from bioactive ceramic powders was measured using an in vitro solubility test, in which the powders were soaked in phosphate buffer solution. Silicon elution was highest in Bioglass (BG), followed by Ceravital (KGS), apatite-wollastonite-containing glass ceramics (A-W.GC), and hydroxyapatite (HA), respectively. Silicon elutions on this in vitro solubility test were correlated with the rates of rapid death in mice following intraperitoneal injection of each of these bioactive ceramic powders. Histopathological examination of the mice revealed nephropathy, which was considered to be the cause of death. The nephropathy was characterized by epithelial degeneration in the renal tubules and increased silicon content throughout the entire kidney, findings suggesting silicon nephropathy. It is considered that, because a large quantity of silicon eluted from the powder was absorbed from the peritoneum, concentration in the glomerular filtrate and urine increased until silicon polymerization occurred, after which the silicon polymer became deposited in the renal tubules. A single injection of furosemide prevented the acute nephrotoxicity of bioactive ceramic powder.

Animals↗

PubMed1992

Differences in ceramic-bone interface between surface-active ceramics and resorbable ceramics: a study by scanning and transmission electron microscopy.

The interface between bioactive ceramics and bone was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The materials were apatite-wollastonite-containing glass ceramic (A-W.GC) as a representative surface-active ceramic, and calcite and beta-tricalcium phosphate (beta-TCP) as resorbable ceramics. Particles of these materials, ranging between about 100 microns and 300 microns in diameter, were implanted into rat tibiae, and specimens were prepared for observation at 8 weeks after implantation. Both SEM and TEM demonstrated that A-W.GC was bonded to bone through a thin Ca-P-rich layer consisting of fine apatite crystals apparently different from those of bone in shape, size, and orientation. Collagen fibers of the bone reached the surface of this layer, and chemical bonding between A-W.GC and the bone was speculated. Calcite and beta-TCP, on the other hand, made direct contact with the bone, and no apatite layer was present at the interface. The surfaces of the implants became rough due to degradation, and bone grew into the finest surface irregularities. However, we were unable to demonstrate any continuity of crystals between the resorbable implants and bone by high-resolution TEM. Accordingly, the bonding strength was considered to be mainly attributable to mechanical interlocking.

Animals↗

PubMed1992

Mechanism and strength of bonding between two bioactive ceramics in vivo.

A study was conducted to examine the mechanism and strength of bonding between two bioactive ceramic plates in vivo. Rectangular plates (15 mm X 10 mm X 2 mm) of Bioglass, apatite-wollastonite-containing glass ceramic (designated A-W.GC), and two types of hydroxyapatite sintered at 900 degrees C and 1200 degrees C (designated HA900 and HA1200) were prepared. Two plates of the same materials tied together with silk thread were implanted subcutaneously into rats. The force required to detach the mutually bonded bioactive ceramic plates was measured 4, 8, 12, and 24 weeks after implantation. The interface between the two bonded plates was examined by SEM-EPMA and thin-film x-ray diffraction analysis. At 24 weeks after implantation, the mutual bonding of Bioglass and A-W.GC was stronger than that of the two HA types. SEM-EPMA and thin-film x-ray diffraction analysis of the bonded area of Bioglass and A-W.GC plates showed bonding zones with apatite in the margins, and a bonding zone with calcite in the center. The greater strength of bonding of Bioglass and A-W.GC plates compared with the two types of HA plate 24 weeks after implantation is explained by the wider bonding zone provided by the calcite layer formed in the center of the plates, which is considered to have been perfused with PO4-poor body fluids resulting from PO4 consumption for apatite formation in the margins.

Animals↗

PubMed1992

A comparative study of ultrastructures of the interfaces between four kinds of surface-active ceramic and bone.

The interfaces between four kinds of surface-active ceramic and bone were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using undecalcified specimens. The materials were Bioglass-type glass (Bioglass), Ceravital-type glass-ceramic (KGS), apatite- and wollastonite-containing glass-ceramic (A-W.GC) and hydroxyapatite (HA). Particles of these materials, ranging between about 100 and 300 microns in diameter, were implanted into rat tibiae, and specimens were prepared for observation at 8 weeks after implantation. All materials were observed to bond to bone through a collagen-free layer consisting of fine apatite crystals distinct from those in bone. The crystals of this apatite layer and those of bone were intermingled at their interface, suggesting chemical bonding. In Bioglass, which had only a glassy phase, several tens of microns of the material surface had changed to such an apatite layer. In KGS and A-W.GC, which had macrocrystals in the glassy phase, an intervening apatite layer about 0.5 micron thick was observed between the materials and bone. Furthermore, fine apatite crystals were also observed among the macrocrystals near the surface of the materials. In HA, which had no glassy phase, an intervening apatite layer was much less distinct and sometimes absent. These differences were considered to be attributable to the differences in chemical composition, crystallization, and solubility of the materials.

Animals↗

PubMed1992

In vitro and in vivo studies on bioabsorbable ultra-high-strength poly(L-lactide) rods.

Ultra-high-strength poly(L-lactide) (PLLA) rods were fabricated using a drawing technique. Rods with a diameter of 3.2 mm and a draw ratio of 2.5:1 showed initial bending strength and modulus values of 240 MPa and 13 GPa, respectively. The purpose of this study was to investigate the in vitro and in vivo degradation of PLLA rods with a draw ratio of 2.5:1. The greater the rod diameter, the longer the bending strength was maintained in phosphate buffered saline at 37 degrees C. The bending strength retention of rods (diam. 3.2 mm) implanted in the subcutis of rabbits was almost equal to that of rods in the in vitro study, while those rods implanted in the medullary cavity of rabbit femora showed a slightly lower bending strength retention. Molecular weight was reduced to the greatest extent in the medullary cavity, followed by in the subcutis and in vitro. The weight of PLLA rods in the medullary cavity was reduced by 22% at 52 weeks and by 70% at 78 weeks after implantation. Histologically, no inflammatory or foreign body reaction was observed in the medullary cavity for 52 weeks. The drawn PLLA rods maintained a bending strength exceeding that of human cortical bone in the medullary canal for a period of 8 weeks, suggesting that the drawn PLLA rods may be useful in the repair of fractured human bones.

Absorption↗

PubMed1992

Solubilization of functional receptors for parathyroid hormone and parathyroid hormone-related peptide from clonal rat osteosarcoma cells, ROS17/2.8.

ROS17/2.8 cells, a cell line derived from a rat osteosarcoma, have abundant receptors for parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP). A particulate membrane fraction was prepared from these cells and it was solubilized using relatively mild conditions with digitonin (0.25%), a nonionic detergent. When radioligands of both PTH and PTHrP were incubated with this membrane fraction in the absence of any protease inhibitor at 15 degrees C, approximately 75% of these radioligands were degraded within 2 hours. This degradative activity was inhibited more effectively by bacitracin than by any of several other protease inhibitors tested. The digitonin-solubilized PTH/PTHrP receptors were radiolabeled in the presence of bacitracin using radioiodinated [Tyr36]PTHrP(1-36) amide (PTHrP(1-36)) and N-hydroxysuccinimidyl-4-azidobenzoate (HSAB), as cross-linker. When an aliquot of the reaction solution was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography, a broad band was observed that had an apparent molecular size of 90,000 daltons (M(r) = 90 kD). This band was no longer seen when the binding was conducted in the presence of 10(-6) M of unlabeled PTHrP(1-36), and it was decreased in density when binding was conducted in the presence of 10(-6) M of unlabeled [Nle8,18, Tyr34] bovine PTH(1-34) amide (NlePTH). The solubilized receptors retained their capacity to bind the radioligand after partial purification by wheat-germ agglutinin affinity-chromatography. The use of relatively mild detergent conditions thus offers a means to solubilize receptors that retain their capacity to bind PTH and PTHrP.

Animals↗

PubMed1992

Influence of substituting B2O3 for CaF2 on the bonding behaviour to bone of glass-ceramics containing apatite and wollastonite.

Glass-ceramics containing crystalline oxy-fluoroapatite (Ca10(PO4)6(O,F2)) and wollastonite (CaSiO3) (designated AWGC) are reported to have a fairly high mechanical strength as well as the capability of forming a chemical bond with bone tissue. The chemical composition is MgO 4.6, CaO 44.9, SiO2 34.2, P2O5 16.3, and CaF2 0.5 in weight ratio. In this study the influence of substituting B2O3 for CaF2 on the bonding behaviour of glass-ceramics containing apatite and wollastonite to bone tissue was investigated. Two kinds of glass-ceramics containing apatite and wollastonite were prepared. CaF2 0.5 was replaced with B2O3 at 0.5 and 2.0 in weight ratio (designated AWGC-0.5B and AWGC-2.0B). Rectangular ceramic plates (15 x 10 x 2 mm, abraded with No. 2000 alumina powder) were implanted into a rabbit tibia. The failure load, when an implant detached from the bone, or the bone itself broke, was measured. The failure load of AWGC-0.5B was 8.00 +/- 1.82 kg at 10 weeks after implantation and 8.16 +/- 1.36 kg at 25 weeks after implantation. The failure load of AWGC-2B was 8.08 +/- 1.70 kg at 10 weeks after implantation and 9.92 +/- 2.46 kg at 25 weeks after implantation. None of the loads for the two kinds of glass-ceramics decreased as time passed. Giemsa surface staining and contact microradiography revealed direct bonding between glass-ceramics and bone. SEM-EPMA showed a calcium-phosphorus rich layer (reaction zone) at the interface of ceramics and bone tissue. The thickness of the reaction zone was 10 to -15 microns and did not increase as time passed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Severe metallosis due to abnormal abrasion of the femoral head in a dual bearing hip prosthesis. A case report.

The authors report on a patient with a case of severe metallosis due to an abnormal abrasion of the femoral head. A primary arthroplasty was performed using a dual bearing hip prosthesis with acetabular bone grafting by ceramic screws. At the time of the revision surgery the synovia was black, and an analysis using a scanning electron microscope and scanning electron microscope-electron probe micro-analyzer revealed numerous small particles of small alumina ceramic on the inner surface of the bearing insert of high-density polyethylene. These particles, which came from the broken ceramic screws due to proximal migration of the prosthesis, scraped the femoral head away. A line and area analysis of the black synovia revealed that the synovia contained metal particles of a cobalt-chromium alloy as well as a cobalt ion. The patient's serum showed elevated concentrations of cobalt, chromium, and molybdenum that dramatically reduced 2 months after the revision surgery.

Adult↗

PubMed1992

Intrinsic radiosensitivity and PLD repair in osteosarcoma cell lines.

The response to radiation of seven osteosarcoma cell lines was analysed by in vitro colony-forming assay and compared with that of eight human fibroblast strains. The values of D0, the surviving fraction after 2 Gy (S2Gy), and the mean inactivation dose (D) of osteosarcoma cells in log-phase culture were significantly higher than those of fibroblast strains (p less than 0.01). PLD (potentially lethal damage) repair of osteosarcoma cells evaluated in the plateau phase of growth showed great variation for enhancement of survival, although all of the values were maximized within 12 h after irradiation. In the osteosarcoma, intrinsic radiosensitivity in vitro reflected the clinical response to radiation. However, the capacity for PLD repair might not be a good indicator for predicting the results of radiation therapy.

Cell Survival↗