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Biomedical subjects

Y Shimoyama

Publications and source records attributed to Y Shimoyama.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Investigation of primary tissue failure in mitral bioprostheses].

A study was conducted on 118 Hancock (HX) porcine valves, 251 Carpentier-Edwards (CE) porcine valves, and the biological valves in children used in the mitral position. Twenty-three HX valves, twenty-seven CE valves, and all valves except one operative death in children were diagnosed as primary tissue failure (PTF). Freedom from PTF for HX valves was 70.1 +/- 6.0% at ten years and for CE valves was 45.7 +/- 17.0% at ten years, although for children it was calculated 0% at eight years (significantly poor results compared with adults). No relation was found between the degree of calcified cusps and the duration of PTF valves used. The ruptures and calcifications of the cusps were most commonly observed in commissure. The peeled off commissures were characteristic in CE valves. Three adults and two children died without reoperation caused by calcified stenotic valves. Since the risk of reoperation was higher in NYHA functional class four, we recommend earlier elective reoperation.

Adult↗
PubMed1990

[A case of bioprosthetic mitral valvular dysfunction due to pannus-formation].

A case of bioprosthetic mitral valvular dysfunction accompanied by mitral stenosis due to pannus is reported. A 69-year-old woman, whose mitral valve had been replaced with a Hancock bioprosthetic valve in June 1979, underwent the second mitral valve replacement in September 1988 because of valvular dysfunction. The ring and cusps of this Hancock valve was partially covered with hard and milky white pannus which resulted in mitral stenosis. The tear of cusp was observed at the point of contact with pannus, which resulted in mitral regurgitation. Histologically, pannus was consisted of two-layered structure, fibrin and collagen fiber, which demonstrated this over-growth was based on thrombus. Main causes of bioprosthetic valve dysfunction are calcification and tear of cusps. But, valvular dysfunction due to pannus-formation described in this case has been experienced very rarely.

Aged↗
PubMed1989

Vector electron paramagnetic resonance spectroscopy with first and second harmonic displays of ferrihemoglobin.

Superimposed plots of electron paramagnetic resonance spectra with the first and second harmonic displays of ferrihemoglobin at pH 9.1 and 90 K were measured at 20 degree intervals of phase angle using a phase-sensitive detector. The high spin signal in the g = 6 region was observed in both displays, and a small splitting of the signal was found in the calculated amplitude spectrum of the second harmonic display, with g values of 5.95 and 6.05. Low spin signals were observed at g = 2.55, 2.25 and 1.82 in both harmonic displays. A signal in the g = 2.05 region was observed only in the second harmonic display. The signal is probably associated with the low spin spectrum; however, its origin is obscure.

Electron Spin Resonance Spectroscopy↗
PubMed1989

Cadherin cell-adhesion molecules in human epithelial tissues and carcinomas.

Two distinct calcium-sensitive cell-cell adhesion molecules were identified in human epithelial tissues and carcinomas using two monoclonal antibodies raised against vulvar epidermoid carcinoma A-431 and human mammary carcinoma MCF-7 and selected on the basis of their activities to disrupt cell-cell adhesion. In immunoblot analysis, these antibodies, designated NCC-CAD-299 and HECD-1, detected main bands of Mr 118,000 and 124,000, respectively. Purified tryptic fragments of the antigen recognized by NCC-CAD-299 showed cross-reactivity with a rabbit antiserum against mouse P-cadherin, indicating that this molecule was the human homologue of P-cadherin. On the other hand, the antigen recognized by HECD-1 showed essentially the same tissue distribution pattern as E-cadherin in the mouse, suggesting that this molecule is the human homologue of E-cadherin. Availability of these monoclonal antibodies to human P- and E-cadherin allowed us to examine their distributions in human tissues immunohistochemically. Both antigens were detected in epithelial tissues, but they showed distributions that were distinct from each other. The antigen recognized by HECD-1 was expressed in almost all epithelial tissues, while distribution of the other one recognized by NCC-CAD-299 was restricted to the basal or lower layers of stratified epithelia in which both antigens were coexpressed. Moreover, immunohistochemical examination of 44 lung carcinomas showed that both molecules were coexpressed in all of them, and suggested that expression of P-cadherin was closely related to the differentiation of carcinoma cells.

Antibodies, Monoclonal↗
PubMed1989

Predictability of in vivo chemosensitivity by in vitro MTT assay with reference to the clonogenic assay.

The MTT assay reported by Mosmann is a rapid and convenient colorimetric assay for cellular growth and survival in vitro. In this paper, the MTT assay was modified as a chemosensitivity test, and its potential was investigated. Using 10 human tumor xenografts in athymic nude mice, the predictability of in vitro antitumor effects of drugs using the MTT assay was compared with that using the clonogenic assay. The MTT assay showed excellent reproducibility, and the predictable rate in this assay was 86.7%, with 100% true-positive and 77.8% true-negative rates, almost equivalent to the 90.0% predictable rate of the clonogenic assay. This method also has several advantages with respect to rapidity, quantitation, management of many samples, and cell number required for the assay. Application of this assay to chemosensitivity testing seems to be valuable and useful.

Animals↗
PubMed1989

MTT assay with reference to the clinical effect of chemotherapy.

Tumor cells from 40 patients were tested by MTT assay. Five thousand to sixteen thousand tumor cells were plated into 96-well microplates with various concentrations of anticancer agents. After incubation for 48 h, the absorbance of each well was detected with an EIA reader and the effects of the agents were evaluated as positive when the inhibition rate was equal to or more than 50%. Normal cells were also processed under the same conditions, and the absorbance for normal cells was lower than that of tumor cells with statistical significance (P less than 0.05). The efficacy rates of MMC, 5-FU, ADM, and CDDP were 16.7, 8.3, 13.9, and 5.6%, respectively. The overall accuracy of this assay for clinical effects was 83.3%, with one false-positive and five true-negative cases. This MTT assay was also assumed to be useful for in vitro chemosensitivity testing of fresh surgical specimens.

Antineoplastic Agents↗
PubMed1989

Molecular cloning of a human Ca2+-dependent cell-cell adhesion molecule homologous to mouse placental cadherin: its low expression in human placental tissues.

P-cadherin is a subclass of Ca2+-dependent cell-cell adhesion molecules present in mouse placenta, where its localization suggests a function of connecting the embryo to the uterus (Nose, A., and M. Takeichi. 1986. J. Cell Biol. 103:2649-2658). We recently identified a human cadherin detected by an mAb capable of disrupting cell-cell adhesion of A-431 cells, and found that it was closely related immunochemically to mouse P-cadherin. Curiously, this cadherin was undetectable in human placenta by immunohistochemical examination (Shimoyama, Y., S. Hirohashi, S. Hirano, M. Noguchi, Y. Shimosato, M. Takeichi, and O. Abe. 1989. Cancer Res. 49:2128-2133). We here report the cloning and sequencing of cDNA clone encoding the human homologue of mouse P-cadherin. The deduced amino acid sequence of the human P-cadherin consists of 829 amino acid and shows striking homology with mouse P-cadherin. On Northern blot analysis, human P-cadherin was scarcely expressed in human placenta in contrast to mouse P-cadherin, which was abundantly expressed in mouse placenta throughout pregnancy, and it was shown that E-cadherin, but not P-cadherin, was the major cadherin molecule in human placenta. Moreover, NIH3T3 cells transfected with human P-cadherin cDNA expressed the functional cadherin molecule, which was identical to the cadherin we had previously identified using the mAb, showing that this molecule really does mediate cell-cell adhesion and that the cadherin we detected immunochemically is undoubtedly human P-cadherin. The results obtained in this study support the idea that P-cadherin plays little role, if any, in Ca2+-dependent cell-cell binding in human placental tissue at least after several weeks of pregnancy.

Amino Acid Sequence↗
PubMed1989

[Long-term results of mechanical valves in aortic position and biological valves in mitral and tricuspid positions].

The long-term results of patients undergoing aortic valve replacement (AVR) with a mechanical valve (AM), mitral valve replacement with a biological valve (MB), and tricuspid valve replacement (TVR) with a biological valve (TB) operated upon from 1977 to 1988 were retrospectively analysed. A total of 899 patients received 1117 valves (381 AM, 633 TB, 103 TB) with a follow-up 3778 patient-years and 4582 valve-years. A significant incidence of thromboembolism, hemorrhage, and endocarditis was not found among AVR, MVR, TVR, or multiple valve replacement. We found a significantly decreased incidence of survival rate in multiple valve replacement compared with AVR or MVR, and a significantly increased incidence of reoperation in MB compared with AM and TB. We use AM and TB in any adult patients as a first choice. However, we prefer a mechanical valve in the mitral position except in patients over 65 years old, who have a short life expectancy, in whom anticoagulation is thought to be difficult, and who desire a biological valve.

Adolescent↗
PubMed1989

[A case of traumatic tricuspid regurgitation].

Tricuspid regurgitation due to nonpenetrating trauma occurred in a 60-year-old male patient who had received chest trauma in a motorcycle accident. He was admitted because of shortness of breath and palpitation on exertion. On admission physical examinations revealed pulsated and dilated jugular veins, hepatomegaly, and systolic murmur. The chest X-ray film showed an enlarged heart and electrocardiograms revealed complete right bundle branch block. Echocardiography demonstrated systolic prolapse of the tricuspid anterior leaflet into the right atrium. Right atrial v wave pressure was 20 mmHg. Tricuspid valve replacement with a Carpentier-Edwards 33 mm using super interpose method was performed successfully 13 years after the trauma. At operation, it was found that the chordae tendineae of the anterior leaflet was ruptured.

Chordae Tendineae↗
PubMed1989

[A thoracic aortic aneurysm with respiratory failure caused by the mechanisms of stenosis of the left bronchus and ipsilateral pulmonary artery--report of a case and review of the literature].

Clinical symptoms of thoracic aortic aneurysm vary widely from symptoms resulting from its rupture to those due to compression of surrounding organs. Furthermore, the onset of symptoms is frequently followed by a fatal outcome unless emergency measures are taken. We have recently experienced a patient who developed respiratory insufficiency caused by an aneurysm of the descending thoracic aorta compressing the left primary bronchus and the right pulmonary artery, the former causing ventilatory failure in the left lung and the latter interfering with blood flow in the right lung. The patient underwent emergency prosthetic graft replacement and showed temporary symptom improvement. However, a postoperative complication of esophageal perforation due to ischemic necrosis occurred and eventually caused acute empyema followed by death. The patient was a 48-year-old male who presented with symptoms similar to bronchial asthma. Angiographic examination (iv-DSA) revealed compression of right pulmonary artery by an aneurysm of the descending thoracic aorta. Bronchoscopic findings included extramural stenosis of the left bronchus accompanied by arterial pulsation. As an emergency measure, artificial blood vessel replacement of the descending thoracic aorta was performed. However, the patient developed postoperative acute empyema and died on the 19th postoperative day. Autopsy revealed ischemic necrosis on the esophageal wall where the aneurysmal lesion had touched before operation. This seems to have formed a perforation into the left thoracic cavity and ultimately to have caused acute empyema. Since we believe that the pathogenesis and clinical course observed in this patient is rather rare, the case is reported in accompanied by relevant data from the literature.

Aorta, Thoracic↗
PubMed1989

[Report of 108 patients with valvular heart disease who underwent re-operations through repeated median sternotomy incision].

108 patients who underwent redo median sternotomy between January 1975 and April 1988 were studied to determine factors affecting risk of cardiac reoperations. (1) Seventeen of 108 patients died, yielding an overall mortality of 15.7%. (2) Preoperative diagnosis had a significant correlation with mortality, which was higher with prosthetic valve endocarditis (50.0%) than with all other indications for reoperation. (3) Operative mortality was related to pre-reoperation functional class: 8.7% for New York Heart Association (NYHA) class II, 9.8% for class III and 27.8% for class IV. (4) Based on the degree of urgency, elective reoperation had a mortality of 5.4%, while emergency procedures carried a mortality of 61.5%. (5) Cardiac catheterization information was available in 53 patients. The pulmonary artery pressure was higher in the died group. There were no significant differences in pulmonary capillary wedge pressure and cardiac index between the survived and died. (6) Operation time, aortic cross clamp time and pump run were significantly longer in the died than in the survived group. The died had more blood loss during operative procedure. To decrease operative mortality, technical improvement and increased experience were necessary for surgeons. We prefer to free entirely pericardial adhesion to facilitate mobilization and evacuate air, and to make intra-cardiac procedure more easier and safety. Furthermore early reoperation before irreversible deterioration occurs was necessary since myocardial function was found to be a major determinant of surgical results.

Adult↗
PubMed1989

[Biological versus mechanical valves in the mitral position].

The long-term late results of isolated mitral valve replacement before April 1981 were retrospectively evaluated in 54 patients receiving a Hancock valve (HX) with a total follow-up of 424 patient-years (py) and 37 patients receiving a Björk-Shiley valve (BS) with a total follow-up of 366 py. There was no significant difference in regard to preoperative age, cardiothoracic ratio, electrocardiogram, or New York Heart Association functional class between the two groups. All of the BS group and 43 of the HX patients received long-term anticoagulant therapy. No significant difference was notable between the two groups in hospital mortality. Actuarial survival rate excluding hospital deaths was 75.5 +/- 6.7% for the HX group, and 80.8 +/- 7.1% for the BS group at ten years (not significant). There was no significant difference between the two groups in overall incidence of thromboembolism (HX 1.4% py, BS 1.9% py), anticoagulant related bleeding (HX 0.5% py, BS 0.8% py), or endocarditis (HX 0.5% py, BS 0.3% py). Actuarial freedom from reoperation at ten years was 69.6 +/- 8.1% for the HX group, and 93.5 +/- 4.4% for the BS group (p less than 0.01). Event free survival excluding hospital deaths at ten years was 49.2 +/- 8.1% for the HX group, 70.6 +/- 8.3% for the BS group (p less than 0.05). We prefer a mechanical prosthesis except in patients over 65 years old, who have a short life expectancy, in whom anticoagulation is thought to be difficult, and who hope a biological valve.

Adult↗