Biomedical subjects

J Toguchida

Publications and source records attributed to J Toguchida.

At least 19 recordsLinked to original sources

PubMed2001

Definitive intraoperative very high-dose radiotherapy for localized osteosarcoma in the extremities.

PURPOSE: To evaluate the outcome and adverse effects in patients with osteosarcoma treated with very high-dose definitive intraoperative radiotherapy (IORT), with the intention of saving the affected limb. METHODS AND MATERIALS: Thirty-nine patients with osteosarcoma in their extremities were treated with definitive IORT. The irradiation field included the tumor plus an adequate wide margin and excluded the major vessels and nerves. Forty-five to 80 Gy of electrons or X-rays were delivered. The median follow-up of the surviving patients was 124 months. RESULTS: The cause-specific and relapse-free 5-year survival rate was 50% and 43%, respectively. Distant metastasis developed in 23 patients; 19 died and 4 were alive for >10 years. Nine local recurrences were found 4-29 months after IORT in the affected limb. No radiation-induced skin reaction or nerve palsy was observed in the patients treated with X-rays. Experiments using phantoms also confirmed that the scatter dose was below the toxic level in the IORT setting with X-rays. CONCLUSIONS: Very high-dose definitive IORT combined with preventive nailing and chemotherapy appeared to be a promising quality-of-life-oriented alternative to treating patients with osteosarcomas in the extremities, although the problem of recurrences from the surrounding unirradiated soft tissue remains to be solved.

Adolescent↗

PubMed2001

Study on the lubrication mechanism of natural joints by confocal laser scanning microscopy.

Natural joints have an excellent lubricating function, but the detailed mechanism is still unclear. To clarify this lubricating mechanism, we observed the behavior of the cartilage surface under the physiological loading condition with confocal laser scanning microscopy in normal and osteoarthritis (OA) cartilage rabbit specimens. Even with a considerable loading condition, in both natural and OA cartilage, the fluid pool area coexisted with the direct contact area. In the junction from the direct contact area to the fluid area, there was a third area with a liquid-crystal arrangement. In OA cartilage, these areas were generally irregular and small. These results suggest that a lubrication system in the fluid phase, such as squeeze film lubrication, might work under severe pressure in normal cartilage, and hyaluronic acid macromolecules in the synovial fluid might form a liquid-crystal structure and support pressure on the cartilage surface, whereas these systems did not affect the OA cartilage.

Animals↗

PubMed2001

Development of the shields for tendon injury repair using polyvinyl alcohol--hydrogel ( PVA-H).

In recent years, marked advances have been made in repair techniques for tendon injury, but the treatment of finger flexor tendon injury is still one of the most difficult and important problems in the orthopedic field. The main problem in tendon repair is adhesion between the tendon and surrounding tissue. To prevent this adhesion and achieve tendon union, we developed adhesion preventive shields for tendon repair using polyvinyl alcohol hydrogel ( PVA-H) with 90% water content, and carried out an implant experiment using the deep flexor tendon of the third toe of domestic fowl. Injured tendons shielded with PVA-H showed union at about 3 weeks after the operation without adhesion to the surrounding tissue and good function such as gliding and range of motion. Neither breakage of the PVA-H shield itself nor infection, nor degeneration in the surrounding tissue were observed. These results confirmed that the tendon itself has repair ability, and the tendon is regenerated by synovial nutrition through PVA-H. High water content PVA-H may have clinically potential and be applicable to adhesion-preventive shields for tendon repair. However, re-rupture was observed, probably due to accidental tendon injury at an early period after the operation. In some cases, tendon immobilization methods to prevent re-rupture might be necessary.

Animals↗

PubMed2001

Role of uppermost superficial surface layer of articular cartilage in the lubrication mechanism of joints.

The uppermost superficial surface layer of articular cartilage, the 'lamina splendens' which provides a very low friction lubrication surface in articular joints, was investigated using atomic force microscopy (AFM). Complementary specimens were also observed under SEM at -10 degrees C without dehydration or sputter ion coating. Fresh adult pig osteochondral specimens were prepared from the patellas of pig knee joints and digested with the enzymes, hyaluronidase, chondroitinase ABC and alkaline protease. Friction coefficients between a pyrex glass plate and the osteochondral specimens digested by enzymes as well as natural (undigested) specimens were measured, using a thrust collar apparatus. Normal saline, hyaluronic acid (HA) and a mixture of albumin, globulin, HA (AGH) were used as lubrication media. The surface irregularities usually observed in SEM studies were not apparent under AFM. The articular cartilage surface was resistant to hyaluronidase and also to chondroitinase ABC, but a fibrous structure was exhibited in alkaline protease enzymes-digested specimens. AFM analysis revealed that the thickness of the uppermost superficial surface layer of articular cartilage was between 800 nm and 2 microm in adult pig articular cartilage. The coefficient of friction (c.f.) was significantly higher in chondroitinase ABC and alkaline protease enzymes digested specimens. Generally, in normal saline lubrication medium, c.f. was higher in comparison to HA and AGH lubrication media. The role of the uppermost, superficial surface layer of articular cartilage in the lubrication mechanism of joints is discussed.

Animals↗

PubMed2001

Development of polyvinyl alcohol-hydrogel (PVA-H) shields with a high water content for tendon injury repair.

The main problem in tendon repair is adhesion formation between the tendon and surrounding tissue. To prevent this, we have developed adhesion preventive shields using polyvinyl alcohol hydrogel (PVA-H) with 90% water content. This implant experiment used the deep flexor tendon of the 3rd toe of the domestic fowl. Injured tendons shielded with PVA-H healed within about 3 weeks without adhesion to the surrounding tissues. Neither breakage of the PVA-H shield itself nor infection or degeneration in the surrounding tissue was observed. These results show that tendon is capable of intrinsic repair, and was able to regenerate using synovial nutrition through the PVA-H. The high water content of PVA-H may be clinically useful and applicable to adhesion preventive shields for tendon repair.

Animals↗

PubMed2000

Translin binds to the sequences adjacent to the breakpoints of the TLS and CHOP genes in liposarcomas with translocation t(12;6).

Myxoid and round-cell liposarcomas share the translocation t(12;16)(q13;p11) creating the TLS-CHOP fusion gene as a common genetic alteration. We previously reported several unique characteristics of genomic sequences around the breakpoints in the TLS and CHOP loci, and among them was the presence of consensus recognition motifs of Translin, a protein that associates with chromosomal translocations of lymphoid neoplasms. We further extended our search for Translin binding motifs in sequences adjacent to breakpoints and investigated whether Translin binds to these sequences in vitro by mobility-shift assay. Computer-assisted search found sequences highly homologous (>70%) with Translin binding motifs adjacent to the breakpoints in 10 out of 11 liposarcomas with the TLS-CHOP fusion genes. All of 13 oligonucleotides corresponding to the putative binding sequences in these cases bind to Hela cell extract and also recombinant Translin protein, although the binding affinity of each motif showed considerable differences. The DNA-protein complex formation was inhibited by non-labeled competitor or anti-Translin antibody, suggesting the specificity of the complex formation. Considering the high incidence and specific binding property, the presence of Translin binding motif may be one of the important determinants for the location of breakpoints in the TLS and CHOP genes in liposarcomas.

Binding Sites↗

PubMed2000

Intra-operative radiation therapy for osteosarcoma in the extremities.

The outcome following intra-operative radiation therapy in the treatment of osteosarcoma in the extremity in 33 patients was evaluated for oncological and functional results. Local recurrence occurred in seven cases, six of which were in a non-irradiated region, indicating inappropriate planning of the radiation field. Twenty-one patients underwent either prosthetic replacement (14) or amputation (7). Irradiated tumours were left in situ in the remaining 12 patients. In this latter group no degenerative joint changes were observed radiologically. Twenty-six patients experienced local complications, of which fracture of the irradiated bone was the most significant. Associated intramedullary nailing showed encouraging results in preventing fracture. Although IORT is effective for the local control of osteosarcoma in extremities, critical patient selection and improvements of treatment protocol are required in order to obtain a satisfactory outcome.

Adolescent↗

PubMed2000

High incidence of SV40-like sequences detection in tumour and peripheral blood cells of Japanese osteosarcoma patients.

Recent studies have revealed the evidence for the significance of SV40 genome in human malignancies. In this paper, the presence of SV40-like sequences was investigated in 54 Japanese osteosarcomas in which mutations of the retinoblastoma (Rb), p53, MDM2, and CDK4 genes had been already analysed. Using polymerase chain reaction and Southern hybridization, SV40-like sequences were detected in 25 cases (46.3%). In most cases, only a part of SV40 genome was detected, and the regulatory region containing enhancer sequences was most frequently found (21/54, 38.9%). There was no apparent relationship between the presence of SV40-like sequences and tumour suppressor genes mutations in each tumour. The SV40-like sequences were also detected in peripheral blood cells of substantial proportion of the patients (43.3%), whereas the incidence was much lower (4.7%) in normal healthy controls. This difference is statistically highly significant (P < 0.0001), suggesting that the presence of SV40-like sequences, even if only a part, may play some roles to predispose individuals to osteosarcoma.

Adolescent↗

PubMed2000

[Multiple exostoses].

Multiple exostoses is a hereditary disease characterized by multiple osteocartilagenous tumors, of which the histological structures are similar to those of normal epiphyses. Genetic linkage has identified three different loci for this disease: EXT1 on 8q, EXT2 on 11p, and EXT3 on 19p. The EXT1 and EXT2 genes were recently isolated and mutation analyses have been performed in a number of patients with different ethnic backgrounds. The data indicate that mutations of these genes occurred in broad regions of each gene, and the loss-of-function mutations were predominant, although there were some missense mutations that may create functionally defective protein. Tumor cells were shown to be homozygous for the mutant allele, which is consistent with the concept of these genes as tumor suppressor genes. Recent progress for the functional analyses has disclosed that these genes encode the protein with glycosyltransferase activity and regulate the diffusion of Hedgehog protein, which is the key molecule for the skeletal development. Further analyses of these genes may provide us with the knowledge for the development of epiphyses, and may open the new research field for the regeneration of epiphyses.

Epiphyses↗

PubMed1999

Characteristics of genomic breakpoints in TLS-CHOP translocations in liposarcomas suggest the involvement of Translin and topoisomerase II in the process of translocation.

Fusion of TLS/FUS and CHOP gene by reciprocal translocation t(12;16)(q32;q16) is a common genetic event found in myxoid and round-cell liposarcomas. Characterization of this genetic event was performed by three methods, Southern blot, RT-PCR, and genomic long-distance PCR in nine myxoid and three round-cell liposarcomas. All but one tumors showed genetic alternations indicating the fusion of TLS/FUS and CHOP gene. Two novel types of fusion transcripts were found, of which one lacked exon 2 sequence of CHOP gene, and the other lacked 3' half of exon 5 of TLS gene. The latter case was caused by a cryptic splicing site which was created by the genomic fusion. Detailed analyses genomic fusion points revealed several sequence characteristics surrounding the fusion points. Homology analyses of breakpoint sequences with known sequence motifs possibly involve in the process of translocation uncovered Translin binding sequences at both of TLS/ FUS and CHOP breakpoints in two cases. Translocations were always associated with other genetic alterations, such as deletions, duplications, or insertions. Short direct repeats were almost always found at both ends of deleted or duplicated fragments some of which had apparently been created by joining of sequences that flank the rearrangement. Finally, consensus topoisomerase II cleavage sites were found at breakpoints in all cases analysed, suggesting a role of this enzyme in creating staggered ends at the breakpoint. These data suggested that sequence characteristics may play an important role to recruit several factors such as Translin and topoisomerase II in the process of chromosomal translation in liposarcomas.

Artificial Gene Fusion↗

PubMed1999

Association of the human NPPS gene with ossification of the posterior longitudinal ligament of the spine (OPLL).

OPLL (ossification of the posterior longitudinal ligament of the spine) is a common form of human myelopathy with a prevalence of as much as 4% in a variety of ethnic groups. To clarify the genetic factors that predispose to OPLL, we have studied ttw (tiptoe walking), a mouse model that presents ectopic ossification of the spinal ligaments similar to OPLL and have found that the ttw phenotype is caused by the nonsense mutation of the gene encoding nucleotide pyrophosphatase (NPPS), a membrane-bound glycoprotein thought to produce inorganic pyrophosphate, a major inhibitor of calcification and mineralization. To investigate a possible role of NPPS in the etiology of OPLL, we have examined its genetic variations in OPLL patients. A total of 323 OPLL patients was screened by means of polymerase chain reaction/single-strand conformation polymorphism analysis covering all the exons and their surrounding introns, plus about 1.5-kb of the promoter region. We identified ten nucleotide variations in the NPPS gene; five of the alterations caused amino-acid substitutions, and two of them were found specifically in OPLL patients. Subsequently, we performed an association study using these variations and found a significant association of an allele, viz., a deletion of T at a position 11 nucleotides upstream from the splice acceptor site of intron 20 (IVS20-11delT), with OPLL; the proportion of the individuals having this deletion was significantly higher (P = 0.0029) in OPLL patients than in controls, indicating that those who have this variation may be more susceptible to the abnormal ossification of the spinal ligaments. Thus, our study suggests that NPPS plays an important role in the etiology of human OPLL.

Aged↗

PubMed1999

Anisotropy of osteoporotic cancellous bone.

To investigate the mechanism underlying femoral neck fracture, it is necessary to determine the various mechanical properties, including the bone strength, of the primary compressive group. We investigated the mechanical anisotrophy of the primary compressive group by comparing differences in its mechanical properties, depending on the loading direction. Twenty-three femoral heads of 20 female and 3 male patients with femoral neck fracture were studied. The mean age of these patients was 79.9 years (range, 63-98 years). A total of 82 cubic specimens (6.5 mm in length) were obtained (one to six specimens from each femoral head). The specimens obtained from each femoral head were randomly assigned into two groups: parallel and perpendicular. The parallel group included 43 specimens, and the perpendicular group included 39 specimens. A compressive load was applied either parallel or perpendicular to the primary compressive group of the specimens in each respective group. Three parameters were obtained: compressive stiffness, maximum stress, and maximum energy. We calculated the regression of three parameters against the square of the apparent dry density. These mechanical properties were compared between the two groups by testing the difference of the slopes in two regression lines by using analyses of covariance, in which two main effects of group (nominal value) and the square of the apparent dry density (continuous value) and an interaction between two factors were modeled. Three parameters were significantly correlated with the square of the apparent dry density in both groups. In all three measurements, the difference of the slopes between two regression lines was significantly different. This means that all three measurements decreased in the parallel group more than in the perpendicular one, as apparent dry density decreased. We consider that the bone strength of the proximal femur decreases more when stress is applied in the longitudinal direction (as in walking) and less when stress is applied in the transverse direction (as in a fall) when bone density decreases.

Aged↗

PubMed1997

Histologic comparison of tibial articular surfaces against rigid materials and artificial articular cartilage.

After endoprosthetic replacement of the femoral head, marked pathologic changes of the acetabulum, such as penetration and ulceration, often occur. These changes are caused by the rigid material surface properties of the prosthesis and the lack of damping effects. In this study, we compared the time-dependent changes of tibial articular surfaces with three kinds of femoral implant under loading conditions in dogs. Marked pathologic changes of the menisci and tibial articular cartilage were observed from 8 weeks after implantation with hard material implants, whereas the tibial joint surface against an artificial articular cartilage was still intact 24 weeks postoperatively. These results showed clearly that marked pathologic changes of the articular cartilage against rigid materials occurred and were caused by the surface properties of the counterfaces and high friction coefficients of ceramic and metal materials used.

Animals↗

PubMed1997

Establishment of an osteoblast-like cell line, MMC2, from p53-deficient mice.

An immortalized cell line exhibiting a well-differentiated osteoblast-like phenotype was established from calvaria of p53 tumor suppressor-deficient mice. This cell line, designated MMC2, showed several osteoblast-like properties such as high alkaline phosphatase activity, expression of type I collagen and osteocalcin mRNA, and differentiated in vitro to produce mineralized extracellular matrix. Alkaline phosphatase activity and the level of osteocalcin mRNA expression and the production of mineralized matrix were significantly enhanced by the addition of ascorbic acid. Although the cells proliferated rapidly and indefinitely, they did not grow in soft agar and were nontumorigenic in nude mice. These characteristics were equivalent to those observed in MC3T3-E1, a well-known osteoblast-like cell line. When inoculated in nude mice, however, MMC2 produced matured bone tissue, which was not observed in the case of MC3T3-E1. Expression of bone morphogenetic protein 2 and 4 and type IA receptor mRNA was demonstrated in cultured MMC2 cells. These results indicate that this new osteoblast-like cell line, MMC2, will be a unique material for the analysis of bone cell biology.

Alkaline Phosphatase↗

PubMed1997

Synthetic osteochondral replacement of the femoral articular surface.

We have studied damage to the tibial articular surface after replacement of the femoral surface in dogs. We inserted pairs of implants made of alumina, titanium and polyvinyl alcohol (PVA) hydrogel on titanium fibre mesh into the femoral condyles. The two hard materials caused marked pathological changes in the articular cartilage and menisci, but the hydrogel composite replacement caused minimal damage. The composite osteochondral device became rapidly attached to host bone by ingrowth into the supporting mesh. We discuss the clinical implications of the possible use of this material in articular resurfacing and joint replacement.

Aluminum Oxide↗

PubMed1996

Loss of heterozygosity on chromosome 17 and mutation of the p53 gene in retinoblastoma.

Loss of heterozygosity (LOH) on chromosome 17 and mutations of the p53 gene were examined in 25 retinoblastomas (RB), consisting of three familial tumors, nine hereditary tumors without family history, 11 non-hereditary tumors, one recurrent tumor and one lung-metastatic tumor. LOH on chromosome 17 was detected in only one of the 23 primary RB. No mutations of the p53 gene were detected in the primary tumors. A recurrent tumor showed LOH on the short arm region of chromosome 17. LOH on chromosome 17 and a point mutation of the p53 gene were also detected in a metastatic tumor. These results suggest that LOH on chromosome 17 and mutation of the p53 gene may not be associated with the development of primary RB, but may play a role in the progression of RB.

Blotting, Southern↗

PubMed1996

Correction of kyphotic deformity of the cervical spine in ankylosing spondylitis using general anesthesia and internal fixation.

Surgical correction of kyphotic deformity of the cervical spine caused by ankylosing spondylitis is usually done using local anesthesia to prevent undue spinal cord compression and paralysis followed by a sudden-extension maneuver. We report a case of kyphotic deformity that was corrected while the patient was under general anesthesia. To prevent cord compression and paralysis and to obtain an accurate and gradual correction, we used a Hartshill rod prebent to the desired angle, and correction was done by tightening sublaminar wires on the rod until the lamina made full contact with it. Somatosensory evoked potential and wake-up tests were also performed. Our successful result shows that correction of kyphotic deformity of the cervical spine in ankylosing spondylitis can be done more accurately and without discomfort using the present method.

Anesthesia↗

PubMed1995

MDM2 gene amplification in bone and soft-tissue tumors: association with tumor progression in differentiated adipose-tissue tumors.

We have studied 107 bone and soft-tissue sarcomas and 8 lipomas for amplification of the MDM2 gene. This gene was amplified in 3 out of 67 osteosarcomas, 3 out of 20 malignant fibrous histiocytomas, 4 out of 20 liposarcomas, and 4 out of 8 lipomas. The amplification was associated with overexpression of mRNA. In osteosarcomas, contrary to previous findings, all amplifications were observed in primary lesions. In liposarcomas, the amplification was seen exclusively in well-differentiated tumors with high frequency (4/5) but not in other subtypes (0/15). In addition, MDM2 amplification was also frequently found in deep-seated intra- or intermuscular lipomas (4/5). Hence, it is suggested that MDM2 amplification plays a significant role in the development of differentiated adipose-tissue tumors. Three well-differentiated liposarcomas with MDM2 amplification coexisted with high-grade dedifferentiated sarcomas, in which MDM2 amplification was also observed. Interestingly, in 2 of these cases, the grades of amplification correlated with the histological grades, indicating an important role of MDM2 overexpression in tumor progression.

Adolescent↗