Search PubMed⌕ Search

Biomedical subjects

Y Hamamoto

Publications and source records attributed to Y Hamamoto.

At least 91 records · Page 5Linked to original sources
PubMed1989

[Histological changes in periodontal tissues of rat molars following perforation of the pulp and its floor].

Histological changes in periodontal tissues of the first maxillary molars of immature rats following perforation down through the floor of pulp chamber were observed with light and electron microscopes. One and two weeks after perforation, ovally shaped epithelial islands were frequently observed in the apical end of the roots. Cellular cementum was being formed rapidly around the islands and the amorphous layer, containing scanty collagen fibrils and microfilaments, was observed between the epithelial islands and cementum. Four and eight weeks after the treatment, the islands were embedded in the cellular cementum and undergoing degeneration. In the bifurcational area, destruction of the periodontal tissues and subsequent proliferation of epithelium derived from the gingiva were observed. The epithelial rests of Malassez were characterized by enlargement of nucleus and cytoplasm. The results indicate that inflammatory stimulation induced histological changes of the odontogenic epithelial cells and enhances the formation of cementum. The possibility that the epithelial cells are associated with the formation of cementum is also suggested.

Animals↗
PubMed1989

[A case of miliary tuberculosis associated with ARDS, DIC and bilateral pneumothorax].

We reported a case of 64 a year-old male patient of miliary tuberculosis associated with ARDS, DIC and pneumothorax, who had a history of gastric ulcer and pulmonary tuberculosis. On admission his chief complaints were fever, fatigue, palpitation, appetite loss and weight loss, and most noticeable abnormalities were bleeding from the gastric ulcer and miliary shadow on the chest x-ray film with hypoxemia. On the day after admission to the hospital he was diagnosed as ARDS as he showed severe hypoxemia due to extensive tuberculous infiltration in bilateral lung fields, and treatment with antituberculous drugs and steroids were started. On the third hospital day DIC appeared on laboratory data, Gabexate mesilate (FOY) for DIC and respirator for ARDS were introduced. Two weeks later pulmonary infiltration, PaO2 and general condition were somewhat improved. On the 15th day after admission pneumothorax occurred on the right side, and on the 20th day on the left. Tube drainage of both pleural cavities, and instillation of OK-432 and Fibrinogen HT into the right pleural cavity were done, but it showed no effect. Two months after admission pouring Fibrinogen HT and thrombin into the left B1+2 and right B1 with cannula washing pipe through the instrument channel of bronchoscope was carried out. A few days later air leakage stopped and collapsed lungs were completely expanded. This method is effective in the case of incurable pneumothorax with pulmonary hypofunction.

Disseminated Intravascular Coagulation↗
PubMed1989

[A case of spontaneous pneumothorax due to metastasis of urinary bladder carcinoma to the lung].

We reported a case of spontaneous pneumothorax associated with pulmonary metastasis of urinary bladder carcinoma. A 73-year-old male patient complaining of chest pain and dyspnea was admitted, who had undergone transurethral resection of the urinary bladder carcinoma and diagnosis of inactive pulmonary tuberculosis based on the chest X-ray film finding one year previously. On admission, chest X-ray film showed right pneumothorax, and the re-expanded chest X-ray film revealed a cystic lesion in the right upper lung field adjacent to the anterior chest wall, corresponding to the previous pulmonary lesion. Three months later, right thoracotomy was performed because of relapse accompanying by profuse air-leakage. There was a pleural fistula on the surface of the cystic lesion and necrotic tissue in it. Drainage bronchi were involved by surrounding tumorous tissue. Histological examination of the specimen from the cyst wall disclosed metastasis of transitional cell carcinoma of the bladder. The probable mechanism of the spontaneous pneumothorax probable consisted of stenosis of the right B3 bronchus caused by the metastatic tumor produced a check valve mechanism leading to cystic lesion, the rupture of which caused the spontaneous pneumothorax.

Aged↗
PubMed1988

Augmentation and stable expression of a novel transcription factor SII in CD4-positive cells on infection with human immunodeficiency virus type-1 (HIV-1).

We have examined the expression of a novel transcription factor SII in HIV-infected cells. Concomitant with the increasing expression of HIV-1 mRNA, the viability of HIV infected cells dropped and the expression of beta-actin gene also diminished. Concurrently, the expression of SII mRNA was stabilized or augmented. The data presented in this communication suggests that in HIV-1 infected cells, selective transcriptional controls were taking place and that a novel transcriptional factor, SII, plays an essential role in HIV-1 expression leading to cytocidal effects.

Actins↗
PubMed1988

Enhancement of human immunodeficiency virus production by natural lymphotoxin.

The effect of natural lymphotoxin (n-LT) on CD4+ MOLT-4 cells and those cells producing human immunodeficiency virus (HIV), MOLT-4/HIVHTLV-IIIB cells, was studied. Four days after treatment with n-LT, a significant cytotoxic/cytostatic effect was observed predominantly on MOLT-4/HIVHTLV-IIIB cells. Furthermore, with regard to the production of HIV, an almost 3- to 5-fold increase of viral particles was observed in MOLT-4/HIVHTLV-IIIB cells 6 h after treatment with n-LT. These data indicate the possibility that this cytotoxic factor is one of the responsible molecules in the pathogenesis of the acquired immunodeficiency syndrome (AIDS).

Antibodies, Monoclonal↗
PubMed1988

Effect of culture supernatant of MT-2 cells on human immunodeficiency virus-producing cells, MOLT-4/HIVHTLV-IIIB cells.

The effect of culture supernatant of MT-2 cells on human immunodeficiency virus (HIV)-producing cells, MOLT-4/HIVHTLV-IIIB cells, was examined. As compared to the effect on MOLT-4 cells, parent cells not infected with HIV, a selective cytotoxic/cytostatic effect on MOLT-4/HIVHTLV-IIIB cells was observed 4 days after treatment with up to 640-fold-diluted MT-2 supernatant. Furthermore, under similar conditions, a 2- to 6-fold increase in the number of HIV particles was detected in the culture of MOLT-4/HIVHTLV-IIIB cells 6 hr after treatment. Complete blocking of these effects by anti-lymphotoxin monoclonal antibody, but not by anti-tumor necrosis factor antibody, indicates that these effects of MT-2 supernatant on MOLT-4/HIVHTLV-IIIB cells are attributable to a lymphotoxin-related cytotoxic factor.

Antibodies, Monoclonal↗
PubMed1987

Elimination of viruses (human immunodeficiency, hepatitis B, vesicular stomatitis and Sindbis viruses) from an intravenous immunoglobulin preparation.

More than 10(4) plaque-forming units (pfu)/ml of HIV are inactivated during the alcohol fractionation step from plasma to fraction (Fr)-II+III, greater than 10(4) pfu/ml is inactivated from Fr-II+III to Fr-II and greater than 10(4) pfu/ml is inactivated during the polyethylene glycol (PEG) fractionation process from Fr-II+III to intravenous IgG (IVIG). The total inactivation rate from plasma to IVIG via Fr-II+III or Fr-II was calculated to be greater than 10(8) or 10(12), respectively. The PEG fractionation method produces an intact and unmodified IVIG. In addition, the PEG fractionation method at a low ionic strength was found to be effective for the elimination of greater than 10(5) units of other viruses, including hepatitis B, vesicular stomatitis and Sindbis viruses.

Chemical Fractionation↗
PubMed1987

Collagen-producing mesothelial cells in adriamycin-induced pleuritis in rat. Microautoradiographic study utilizing tritiated proline.

By the microautoradiographic method using 3H-proline, collagen production by mesothelial cells was investigated in adriamycin-induced pleuritis in rats. In subpleural granulation tissue formed at 4 to 7 days after the intrapleural injection of adriamycin, proliferating fibroblasts and primitive mesenchymal cells were most intensely labeled, and abundant deposition of collagen and acid mucopolysaccharides were demonstrated about these cells. It is thus concluded that these subpleural mesenchymal cells are mainly responsible for the fibrosing process. Labeling was also observed in some reactive mesothelial cells and macrophages free-floating in the pleural exudate. Several ultrastructural differences between labeled mesothelial cells floating in the fluid and lining the pleural surface were confirmed, suggesting a change in ability to synthesize collagen during mesothelial desquamation. It seems likely that these labeled mononuclear cells in the effusion, attached to the pleural wound surface, support fibrosis performed by underlying collagen-synthesizing mesenchymal cells. Pleural fibrosis disappeared by 10 days, when mesothelial regeneration was almost complete. Probably this change may be due to fibrinolytic activity caused by regenerative mesothelial cells derived from subpleural mesenchymal cells.

Animals↗
PubMed1987

Inhibitory effect of 2',3'-didehydro-2',3'-dideoxynucleosides on infectivity, cytopathic effects, and replication of human immunodeficiency virus.

It is generally accepted that human immunodeficiency virus (HIV) is the etiologic agent of the acquired immunodeficiency syndrome and related diseases. In this report, we demonstrate the antiviral effect of nucleoside analogs 2',3'-didehydro-2',3'-dideoxythymidine (DHT) and 2',3'-didehydro-2',3'-dideoxycytidine (DHC) by using human T-cell lymphotropic virus type I-carrying MT-4 cells, which are extremely susceptible to HIV infection. These agents efficiently inhibited the cytopathic effects and expression of HIV-specific antigens in MT-4 cells after infection of the virus. Both DHT and DHC also strongly blocked viral replication as determined by our quantitative bioassay system using a plaque-forming assay. These antiviral effects were obtained at concentrations at which the drugs produced little or no toxicity and were comparable to those with 3'-azido-3'-deoxythymidine and 2',3'-dideoxynucleosides. These findings warrant further investigation of the use of DHT and DHC for the treatment of the acquired immunodeficiency syndrome and related diseases.

Antigens, Viral↗
PubMed1986

Cytological and ultrastructural characteristics of DNA synthesizing mesothelial cells in pleural effusion.

Cytologic examination of 3H-thymidine-labeled mesothelial cells in the pleural fluid revealed that single and small-sized cells with slight basophilic cytoplasm scarcely stainable by PAS and colloidal iron are in the DNA-synthetic phase and that these are exfoliating cells from the pleural surface. While abnormal labeling in a few arranged and binuclear cells suggesting accelerated or disturbed mesothelial mobilization was frequently found in congestive cardiac failure, liver cirrhosis, and uremia, it never occurred in single and large-sized activated cells possessing rich PAS-positive granules, cells in large clusters or sheet-like arrangements, or multinuclear giant cells. Transmission electron microscopical observation of these labeled cells proved that a smooth cellular surface and scant intracytoplasmic organelles, by which undifferentiated cells are generally characterized, are essential for DNA-synthesizing mesothelial cells. Probably as a result of some pleural irritation, surface lining cells immediately enter the cell cycle and at once revert to an undifferentiated form capable of DNA synthesis, after which they may be released as a single form, and differentiate and transform into mature, activated cells with a bleb-like surface structure or microvilli, and finally may proliferate in the fluid.

Adult↗
PubMed1984

A study on the mesothelial cell kinetics in pleural effusions by DNA cytophotometry and autoradiography with tritiated thymidine.

On 34 samples of pleural fluid a cell kinetic study of mesothelial cells was carried out by Feulgen-DNA cytophotometry and the autoradiographic estimation of 3H-thymidine uptake. The generation time of mesothelial cells in malignant effusions was found to be shorter than in non-malignant ones, thought he cellular activity for both effusions was essentially the same. Furthermore, with the development of complicating pleuritis from the early stage to the fibrino-fibrous stage, the appearance rate of 3H-thymidine labeled and activated mesothelial cells in the DNA synthetic phase changed quite differently in both effusions. The differences were thought to be due to neoplastic invasion itself or inflammatory reactions to the neoplastic growth.

Adult↗
PubMed1983

Polyploid mesothelial cells in pleural fluid.

The Feulgen-DNA content of the mesothelial cells in non-malignant pleural fluids was cytophotometrically examined on 21 autopsy cases, in 13 of which (62%) polyploid mesothelial cells with greater than tetraploid nuclear DNA content were found. In 7 the polyploid cells appeared at the rate of 6 to 14%, 6 of which had suffered from uremia or congestive cardiac failure. The appearance rate was closely related to such pleural pathologic changes as prominent edema, diffuse hemorrhage, and fibrin precipitation. The occurrence of these polyploid cells was considered to be the result of mitotic abnormalities in the affected pleural area. Since polyploid mesothelial cells are not rare in certain non-malignant pleural fluids, a trial to establish the diagnosis of malignancy based on DNA cytophotometry alone is not recommended.

Adolescent↗