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Biomedical subjects

Y Kotoura

Publications and source records attributed to Y Kotoura.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1993

Time-dependent changes in the mechanical properties of zirconia ceramic.

Zirconia has received special attention, mainly because of its high strength and toughness. However, there is some controversy about the time-dependent deterioration of its mechanical properties. To examine the change in mechanical properties of zirconia ceramics in vivo and in vitro, tetragonal zirconia polycrystal pieces were introduced into the medullary cavity of the tibia in Japanese rabbits and animals were sacrificed after 2, 4 and 6 weeks and 6, 12, and 30 mo, respectively. Alumina ceramic and hydroxyapatite (HAP) pieces were used as controls to investigate the differences in biocompatibility. Zirconia showed a bending strength of over 1000 MPa initially, and little time-dependent change in strength was found in both in vivo and in vitro environments. x-Ray analysis showed little change in the transformation rate, i.e., less than 5 mol % in vivo and in vitro over a period of 3 years. To estimate time-dependent changes in zirconia over a longer period, zirconia pieces were placed in 95 degrees C saline solution for over 3 years and their mechanical properties examined at chosen intervals. No serious decrease of bending strength was found over the 3-year period under these conditions. It is concluded that zirconia can be used clinically because it retains a bending strength of over 700 MPa under any experimental conditions for over 3 years.

Animals↗
PubMed1993

Localized hyperthermic treatment of experimental bone tumors with ferromagnetic ceramics.

Localized hyperthermic treatment was carried out with use of a metastatic bone tumor model in rabbits. The experimental bone tumor was created by transplantation of pieces of tumor line VX2 into the medullary canal of rabbit tibiae. Two weeks after the transplantation, a ferromagnetic ceramic pin was inserted in the medullary canal. Then, hyperthermia (HT) of the tumor was accomplished with use of an alternating magnetic field for 50 min. All the rabbits were killed 5 weeks after tumor transplantation, and the therapeutic effect was evaluated histologically and roentgenographically. Almost all the tumor cells within the bone marrow were killed by this procedure. The area of tumor necrosis in the HT group was significantly larger than in the control group. The pathological fracture rate and displacement rate were reduced significantly by this treatment (38.5 and 0%) compared with the controls (92.3 and 92.3%). Therefore, HT with the use of ferromagnetic ceramics was effective for local control of malignant bone tumors and seems to be a promising new method of treatment.

Animals↗
PubMed1993

A comparison of the metabolic changes after the distal splenocaval and portacaval shunts.

The distal splenorenal shunt (DSRS) is the recommended procedure for selective variceal decompression, but its use may be limited in patients who have undergone left nephrectomy, those with an anatomically aberrant relationship between the splenic and left renal veins, and those whose preoperative angiographic findings suggest a risk of developing postoperative renal vein hypertension. For these clinical situations, the selective distal splenocaval shunt (DSCS) is a useful alternative to the DSRS. However, the metabolic consequences of the DSCS have not yet been studied in detail and therefore, using a canine model, the metabolic changes following the DSCS and the portacaval shunt (Eck) were compared. The metabolic changes observed following the Eck were hyperammonia and amino acid imbalance, while those following the DSCS were similar to those of the control dogs. In terms of the hepatic adenosine triphosphate level, which reflects hepatic mitochondrial function, the DSCS dogs were also similar to the control dogs. These data suggest that there was no metabolic disadvantage of the DSCS compared to the control.

Adenosine Triphosphate↗
PubMed1993

Osteocyte viability after high-dose irradiation in the rabbit.

The effects of high-dose irradiation on the metabolism of osteocytes were examined with respect to RNA synthesis. A single 50-Gy dose of high-energy electron beam was given to the proximal tibia of rabbits. RNA synthesis by osteocytes was quantified by counting the silver grains on autoradiographs of cultured bone fragments, using 3H-cytidine as a tracer. At four, 12, and 52 weeks after irradiation, RNA synthesis by the irradiated osteocytes was 72, 62, and 79%, respectively, of that by nonirradiated osteocytes. The proportion of labeled osteocytes, conversely, was not reduced at four and 12 weeks, but was significantly reduced at 52 weeks after irradiation. The reduction in the RNA synthesis of osteocytes occurs fairly quickly, whereas reduction in the number of viable osteocytes occurs slowly as a delayed sequela. Histologic examination showed that the partial recovery of RNA synthesis observed at 52 weeks was attributable to the appearance of a fraction of new osteocytes, i.e., subendosteal apposition of new bone to the original, degrading cortex. These observations demonstrate the process of recovery from radiation damage.

Animals↗
PubMed1993

[Intraoperative radiotherapy in malignant bone tumors].

When a bone tumor is confirmed to be malignant by biopsy and has not expanded into the soft tissue, intraoperative radiation therapy (IORT) is indicated for most parts of the four extremities. The irradiation area is exposed through an extensive skin incision, and the soft tissues are opened and retracted away from the irradiation area, leaving a layer of normal tissue directly covering the tumor. The irradiation is performed with 12-26 MeV electron beams from a betatron at a dose of 50-100 Gy, depending on the radiosensitivity of each tumor. The multifocal bilateral irradiation method is the best for minimizing complications of the soft tissues. Since 1978, we have performed IORT in combination with chemotherapy in 41 cases of malignant bone tumors and experienced only five cases of tumor recurrence one in the irradiated area and four in the non-irradiated area. Joint function in the irradiated limb was excellent. However, due to the high incidence of pathological fracture after IORT in osteolytic tumors, the limb eventually had to be replaced by a prosthesis. After 1984 when cisplatinum was introduced to our chemotherapy protocol, the cumulative 5 year survival rate increased to 81%, with the irradiated lesion preserved in situ in osteoblastic tumors and replaced with a prosthesis in osteolytic tumors.

Adolescent↗
PubMed1993

Alveolar soft-part sarcoma. A report of ten cases.

The clinical and pathologic features of ten cases of alveolar soft-part sarcoma (ASPS) were observed in subjects aged ten to 49 years. Eight were male and two were female. The lesion involved the thigh in six cases and the adjacent bone in three. All lesions were retrospectively classified as high risk (Stage II or III of Enneking's staging system), and distant metastasis to lung or bone was noted at initial presentation in four patients. Three patients died with distant metastases at a mean time of three years seven months after diagnosis. The mean interval from initial presentation to detection of distant metastasis was nine months; and the mean interval from detection of metastasis to death was three years two months. Ultrastructural studies demonstrated typical organoid arrangement of the neoplastic cells surrounded by a basement membrane with close attachment of individual cells to the basal lamina. No local recurrence, even in cases with inadequate tumor control, and the tendency for distant metastasis demonstrated in the current series, reemphasized that management of metastasis is most important in the treatment of ASPS.

Adolescent↗
PubMed1993

Analysis of hepatic encephalopathy after distal splenorenal shunt--PTP image and pancreatic hormone kinetics.

The Warren-Zeppa selective distal spleno-renal shunt is aimed at decompressing esophageal varices while at the same time ligating left gastric, gastroepiploic and umbilical veins. But in the long term follow-up loss of shunt selectivity was observed in a number of cases (7/76), with hepatic encephalopathy resulting in 9.3%. In this study, we carried out percutaneous transhepatic portography and investigated pancreatic hormone kinetics in portal blood after arginine load, mainly in cases of hepatic encephalopathy after distal splenorenal shunt compared with non-encephalopathy cases of LC + Varix. These data suggested that as a cause of encephalopathy after distal splenorenal shunt, (1) a marked decrease in portal blood flow due to portal systemic shunt via the pancreatic vein was considered from PTP image, (2) a marked decrease in I/G ratio was considered from pancreatic hormone kinetics in portal blood.

Blood Glucose↗
PubMed1993

Scintigraphic evaluation of tenosynovial giant-cell tumor using technetium-99m(V)-dimercaptosuccinic acid.

Technetium-99m(V) dimercaptosuccinic acid (DMSA) and 67Ga-citrate scintigraphy were performed in three patients with primary and recurrent tenosynovial giant-cell tumor (one localized type and two diffuse type). In all cases, 99mTc(V)DMSA showed marked accumulation in all primary and recurrent tumors; however, 67Ga-citrate showed no accumulation in any of the tumors. Technetium-99m(V)-DMSA scintigraphy was useful in detecting tenosynovial giant-cell tumor and in diagnosing recurrence of this tumor.

Adult↗
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

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

Extensive en bloc resection of regionally recurrent carcinoma of the rectum.

To remove regionally recurrent cancer of the rectum completely, more radical extensive resections were attempted than the conventional ones in 35 patients. Twenty-two patients underwent total pelvic exenteration. In 23, sacral resection was done, combined with other procedures including excision of the entire circumference of the lower pelvic ring. There were two hospital deaths. Delayed wound healing was seen in ten. Preoperative severe pain was alleviated in 18. Also, perineal ulcer, vaginal bleeding, bloody stools, and tenesmus disappeared. Of the four 5-year survivors (estimated rate, 23%), only one was disease-free. A second recurrence was seen in 27 patients, of whom 23 had regional failure. It was concluded that so-called local recurrence is a lesion more widespread than indicated by imaging and biopsy. Therefore, even the most radical resection rarely can cure this disease. However, such a surgical procedure can afford more effective palliation than other treatments and may prolong life in selected patients significantly.

Adenocarcinoma↗
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

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↗
PubMed1992

Long-lasting tolerance of articular cartilage after experimental intraoperative radiation in rabbits.

In experimental intraoperative irradiation, 18 adult rabbits received a single, 50-Gy dose of x-radiation at a unilateral knee joint, and subsequent changes in the articular cartilage were examined over a 15-month period by histology, scanning electron microscopy, and autoradiography. Although the subchondral bone showed histologically typical findings of osteonecrosis three to nine months postirradiation, the articular cartilage revealed no obvious degenerative changes during the entire study period. Scanning electron microscopy revealed normal collagen architecture in the irradiated cartilage for as long as 15 months postirradiation. Autoradiography demonstrated active RNA synthesis by the irradiated chondrocytes during the same period. These results indicate that articular cartilage tissue tolerates intraoperative radiotherapy without sustaining serious degenerative changes, unless possible collapse or contracture disturbs its biomechanical integrity. The survival of articular cartilage can be advantageous for this type of limb-salvage surgery in the treatment of malignant bone tumors around a synovial joint.

Animals↗
PubMed1992

Measurement of synovial fluid volume: a new dilution method adapted to fluid permeation from the synovial cavity.

A new dilution method was developed to measure the synovial fluid (SF) volume in a single knee joint of a rabbit. In this dilution method, we used 2 different kinds of dextrans, one having a mean molecular weight (M(r)) of 487,000 and labelled with fluorescein isothiocyanate (FITC) as a marker, and the other M(r) of 300,000 to give hypertonicity to the solution. By employing these high M(r) dextrans in their optimal concentrations, we were able to minimize the inevitable transsynovial shift of the fluid and marker after intraarticular injection. The original SF volume was then calculated using the fluorescence intensities of the injected and retrieved fluids. By determining the accurate volume of SF, it became possible to measure per joint the protein and hyaluronic acid contents in SF as well as the total and differential cell counts. The results obtained by this new method were reasonable and consistent, except for volume, with the reported results based on pooled samples from multiple joints. We believe that the method can contribute to the analysis of SF changes under various conditions in small laboratory animals.

Animals↗
PubMed1992

Surgical treatment of giant-cell tumors of the spine.

Three cases of relatively uncommon giant-cell tumors in the third cervical and first thoracic vertebra and the sacrum were treated surgically by radical resection and reconstruction. The tumor in the third cervical vertebra was treated by incomplete excision and anterior arthrodesis at a local hospital without pre- or postoperative radiotherapy. A recurrence was noted after four months, however, and an emergency operation was performed for severe quadriplegia. After posterior decompression, the tumor was resected by the lateral approach, and an autograft was performed. The tumor in the first thoracic vertebra was removed simultaneously by the anterior, posterior, and lateral approaches, and reconstruction was performed. The sacral tumor, which was radioresistant, was totally excised, and reconstruction was performed. Using these treatments, excellent results have been recorded after follow-up intervals of 1.5, three, and six years. Because of advancements in preoperative imaging techniques and better surgical techniques, radical resection is the recommended treatment for giant-cell tumors located in the spine.

Adult↗