Search PubMed⌕ Search

Biomedical subjects

Y Yuasa

Publications and source records attributed to Y Yuasa.

At least 19 recordsLinked to original sources
PubMed1992

Constitutional translocation t(4;22) (q12;q12.2) associated with neurofibromatosis type 2.

We report on a female patient with bilateral acoustic neurinomas and other tumors in the central nervous system (neurofibromatosis type 2: NF2) and the constitutional translocation, t(4;22) (q12;q12.2). The precise identification of the translocation breakpoint (q12.2) on chromosome 22 implies the refined localization of a gene responsible for NF2, and would provide a clue to its molecular characterization and to the isolation of the gene. Chromosomes of a paraspinal neurinoma from the patient were also analyzed, and the same karyotype as seen in cultured peripheral lymphocytes was found. The patient's father was also a carrier of the translocation, but he had no clinical symptoms of NF2, nor did other relatives. Several explanations are offered for the different expression of the translocation between the patient and her father.

Adult↗
PubMed1992

Mutations in c-K-ras 2 gene codon 12 during colorectal tumorigenesis in familial adenomatous polyposis.

Colorectal carcinomas may be induced from adenomas, or they may occur de novo. To clarify the histogenesis of colorectal carcinomas, point mutations in codon 12 of the c-K-ras 2 gene in neoplasias of familial adenomatous polyposis patients were examined. Nineteen colorectal advanced carcinomas, 135 adenomatous polyps, 9 hyperplastic polyps, and 27 normal colonic mucosae were obtained from 48 patients. In 27 normal mucosae and 9 hyperplastic polyps, a mutation in the K-ras gene was not detected. Mutations were detected as follows: 0 of 24 in adenomas with mild atypia, 10 of 77 in adenomas with moderate atypia, and 24 of 34 in adenomas with severe atypia. The incidence of mutations in c-K-ras 2 codon 12 is correlated with the degree of atypia of adenomas. However, only 5 such mutations were detected in 19 advanced carcinomas, indicating that the mutation frequency in advanced carcinomas is much lower than that in adenomas with severe atypia. If a mutation of c-K-ras 2 gene is an important component in the formation of adenocarcinoma, these results did not confirm the successive development from adenomas with severe atypia to advanced carcinomas as the main route for colorectal carcinogenesis in familial adenomatous polyposis patients.

Adenomatous Polyposis Coli↗
PubMed1992

Bladder tumor staging: comparison of conventional and gadolinium-enhanced dynamic MR imaging and CT.

With computed tomography (CT) and unenhanced magnetic resonance (MR) imaging, stage pT3b extravesical extension and beyond can be diagnosed, but tumors confined to the bladder wall (stages pT1-pT3a) are poorly delineated. To determine whether visualization of such tumors could be improved with gadolinium-enhanced MR imaging, dynamic breath-hold T1-weighted MR images were obtained after intravenous infusion of 0.1 mmol/kg gadopentetate dimeglumine in 79 patients (86 tumors). Conventional MR images, CT scans, and histologic correlation were available in all cases. With dynamic gadolinium-enhanced MR imaging, the mucosa could be distinguished from the muscular layers of the bladder wall. Staging accuracy with this technique was 85% (73 of 86), which was significantly better than with CT (55%; 47 of 86) (P < .005) or conventional MR imaging (58%; 50 of 86) (P < .05). The accuracy of staging the intramural extent (pT1-pT3a) of bladder tumors was thus improved with gadolinium-enhanced dynamic MR imaging.

Adult↗
PubMed1992

[A case report of replacement of the extracardiac conduit for tetralogy of Fallot: reconstruction with autogenous tissue around the conduit].

Replacement of the valved extracardiac conduit with autogenous tissue was performed on a 13-year-old female. The procedure was based on that reported by Danielson in 1987. She underwent the first operation for tetralogy of Fallot with pulmonary atresia using a valved extracardiac conduit (#16 mm Björk-Shiley valve) 8 years ago. Recently, she complained exertional dyspnea and chest pain. Reoperation was scheduled because of bleeding tendency, somatic growth of the patient, and severe distal anastomotic stenosis of the conduit by right ventriculogram. At operation, the valved conduit was removed under cardiopulmonary bypass, and autogenous connective tissue around the conduit was preserved as the posterior wall of the new conduit. An onlay patch (pericardial monocusp patch) was sutured to form the roof of the new tract. Postoperative catheterization showed no residual stenosis or pressure gradient between the right ventricle and the pulmonary artery. This technique is useful as the replacement of extracardiac conduit because of its simplicity, no necessity of postoperative anti-coagulant therapy, and possibility to make a generous-sized new outflow tract.

Adolescent↗
PubMed1992

[A successful surgical treatment of chronic traumatic mid-descending thoracic aortic aneurysm].

A 48-year-old woman with chronic mid-descending thoracic aortic aneurysm was successfully repaired. She received a blunt chest trauma due to automobile accident at July in 1988. Left upper lobectomy was performed for her lung contusion. March 1990, she admitted our hospital with abnormal shadow revealed by a chest roentgenogram. A computed tomogram of the chest and an aortogram revealed two false aneurysms. One of them was located at mid-descending thoracic aorta and another was aortic isthmus. Under a partial femoral veno-arterial bypass, a Dacron graft replacement of mid-descending thoracic aorta was performed and aneurysm of isthmus was wrapped by Teflon mesh after the left pneumonectomy. 2 months after the operation, bronchopulmonary fistula occurred at the left bronchial stump. The fistula was successfully covered with major omentum. The mid-descending thoracic aortic aneurysm due to blunt chest trauma is rare. The traumatic aortic aneurysms commonly occur aortic isthmus or ascending aorta. Initial diagnosis of traumatic mid-descending thoracic aortic aneurysm is often missed or delayed. Careful follow up is need and when an abnormality is revealed by chest roentgenogram, computed tomogram and aortogram should be obtained to make diagnosis of chronic traumatic aneurysm.

Aorta, Thoracic↗
PubMed1992

[A resected case of thymolipoma].

We reported a resected case of thymolipoma, which has been hardly experienced. The patient was 21-year-old female and consulted a doctor for general fatigue. Chest roentgenogram revealed a mass-like shadow at the right lower mediastinum, which was suspected mediastinal tumor. The mass of right anteroinferior mediastinum, which was clearly shown by chest CT scan and MRI, was continued to the right lobe of the thymus. Under a diagnosis of anterior mediastinal tumor, operation was carried out. The tumor, which was 10 x 8 x 7 cm in diameter and 160 g in weight, was removed together with right lobe of the thymus. Histological diagnosis of thymolipoma was obtained from the resected specimen.

Adult↗
PubMed1991

[Fallopian tube recanalization with a catheter system--experience in the use of a balloon catheter].

Fallopian tube obstruction is one of the most difficult problems in the treatment of infertility. This report gives the results of a pilot study on the transcervical recanalization of the occlusive fallopian tube. Selective catheterization of the uterine cornu was applied through a balloon catheter, which was wedged at the internal uterine os. In 16 occlusive fallopian tubes of 11 cases, the catheterization procedure was attempted and accomplished with a 87.5% success rate. Recanalization was successful in 75.0% of the affected tubes. Subsequent pregnancy was confirmed in three cases. This convenient technique is safe and effective and it will be accepted as the first choice in the diagnosis and treatment of fallopian tube obstruction.

Adult↗
PubMed1991

Normal human chromosome 5, on which a familial adenomatous polyposis gene is located, has tumor suppressive activity.

The suppressive activity of normal human chromosome 5 was detected by means of the chromosomal transfer technique using DT cells as recipients. A hybrid clone, which exhibited reduced tumorigenicity, contained chromosomal regions such as 5pter-p15, q21 and q33-qter. Since a familial adenomatous polyposis gene has been reported to be located at 5q21-q22, the suppressive activity of chromosome 5 might be due to this gene.

Adenomatous Polyposis Coli↗
PubMed1991

Efficacy of gadolinium-diethylenetriaminepentaacetic acid-enhanced magnetic resonance imaging for differentiation between superficial and muscle-invasive tumor of the bladder: a comparative study with computerized tomography and transurethral ultrasonography.

Gadolinium-labeled diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) was evaluated in an effort to clarify whether MRI could replace or be proved to be superior to computerized tomography (CT) and/or transurethral ultrasonography. A total of 57 bladder cancer patients was evaluated. MRI was performed with a superconducting magnet operating at 1.5 Tesla. The images acquired were multisections, having a fast spin-echo pulse sequence of less than a 14-second breath holding. Serial scans were performed before and immediately after Gd-DTPA venous injection. The findings on different imaging techniques were compared with the histological stagings. A proper diagnosis was made in 42 of 57 cases (73.7%) by Gd-DTPA-enhanced MRI, in 27 of 57 (47.4%) by CT and in 31 of 57 (54.4%) by transurethral ultrasonography when comparing the histological findings. The sensitivity and specificity for differentiating superficial and muscle-invasive tumor of each imaging method were, respectively, 96.2 and 83.3% in Gd-DTPA-enhanced MRI, 96.0 and 58.3% in CT, and 88.0 and 66.7% in transurethral ultrasonography. These data suggest that the staging of bladder cancer by Gd-DTPA-enhanced MRI appears to be superior and more accurate than the staging obtained by CT and transurethral ultrasonography.

Adult↗
PubMed1991

Steroid-responsive painful ophthalmoplegia in childhood: sphenoid sinusitis presenting as Tolosa-Hunt syndrome.

A childhood case of painful ophthalmoplegia which responded well to steroids was described. Although the clinical features suggested Tolosa-Hunt syndrome (THS), serial magnetic resonance imagings (MRI) revealed ethmoid and sphenoid sinusitis in this 7-year-old boy. It was considered that multiple factors such as allergy, viral infection and swimming predisposed him to develop severe sinusitis and gave rise to his painful ophthalmoplegia.

Child↗
PubMed1991

Higher frequency of point mutations in the c-K-ras 2 gene in human colorectal adenomas with severe atypia than in carcinomas.

Human colorectal carcinomas may be induced from adenomas or they may occur de novo. To examine which is the main pathway, we analyzed point mutations at codon 12 in the c-K-ras 2 gene in 73 colorectal carcinomas, 13 metastatic tumors, 72 adenomas and 30 normal tissues. The c-K-ras 2 codon 12 mutation frequency was 0/30 in normal tissues, 0/17 in adenomas with mild atypia, 3/37 (8.1%) in adenomas with moderate atypia, 15/18 (83.3%) in adenomas with severe atypia, 19/73 (26.0%) in primary carcinomas and 3/13 (23.1%) in metastatic tumors. The mutation frequency in adenomas with severe atypia was much higher than that in carcinomas. These results indicate that many colorectal carcinomas may not be induced through adenomas with severe atypia.

Adenoma↗
PubMed1991

Mandibular reaction time to auditory and visual signals in young and elderly subjects.

Mandibular reaction time was measured in young and elderly volunteers. Each subject was instructed to open the jaw from the closed position and to close the jaw from the open position as quickly as possible after perceiving an auditory or visual signal. The reaction time of the elderly subjects to both signals was significantly slower than that of the young subjects. This was due almost entirely to prolongation of the premotor time component. There was no difference in the maximum velocity of the jaw movement between the two groups of subjects.

Acoustic Stimulation↗
PubMed1991

Long-term explant culture of human colon and a 3-step transformation model for rat colonic epithelium.

Our previous studies have suggested that colonic epithelium from rodents pretreated in vivo with suboptimal doses of carcinogen could be more easily maintained in explant culture. Transformation of colonic epithelium from these explants may be induced by subsequent exposure to additional genotropic agents. Therefore, we describe the development of a 3-step transformation model which uses (1) in vivo pretreatment with a suboptimal dose of 1,2-dimethylhydrazine (DMH) followed by (2) in vitro organ culture and exposure to xenotropic murine sarcoma virus (X-MSV), and finally (3) xenograft maintenance in nude mice to allow sufficient time for transformation. Male Wistar rats were injected intramuscularly with 20 mg DMH/kg 10 times per week followed by the removal and explant culture of the colon, which was then treated in vitro with X-MSV, and transplanted into nude mice after 1 week of culture. All the nude mice (n = 6) transplanted with rat colon explants contained viable xenograft explant epithelium and 1 of the 6 showed transformation. Our results demonstrate that the epithelium from animals pretreated with suboptimal doses of carcinogens can be easily transformed. We also demonstrate that human colonic epithelium is viable for an extended period of time in this model. Based on these results, we hypothesize that such a 3-step transformation model is applicable for carcinogenesis studies of various organs from different species, including human if one uses dysplastic or 'pre-neoplastic initiated' tissues obtained at surgery (e.g., ulcerative colitis; Barret's esophagus, etc.).

Animals↗
PubMed1991

Quantitative assay of terminal deoxynucleotidyl transferase (TdT) activity using monoclonal antibodies.

Terminal deoxynucleotidyl transferase (TdT) is an important marker for the diagnosis and the therapy of leukemia and lymphoma patients. In this study, we developed the quantitative method for the assay of TdT antigen in leukemic cells using a combination of monoclonal and polyclonal antibodies prepared for this enzyme. High correlation was obtained between the values measured by biochemical assay and enzyme-linked immunosorbent assay (ELISA). This method (ELISA), using antibodies to TdT, permits the rapid and quantitative estimation of TdT antigen in leukemic cells.

Antibodies, Monoclonal↗