Biomedical subjects

T Asai

Publications and source records attributed to T Asai.

At least 433 records · Page 24Linked to original sources

PubMed1990

Remarkable activities of nucleoside triphosphate hydrolase in the tachyzoites of both virulent and avirulent strains of Toxoplasma gondii.

Dithiothreitol-dependent MgATP2- and Mg-ADP- hydrolytic activities owing to nucleoside triphosphate hydrolase were examined kinetically in tachyzoite cells of five strains of Toxoplasma gondii with various virulence. The tachyzoites of all the strains were revealed to have a high ATP and ADP hydrolytic potency. The value of Vmax and Km obtained from each strain indicated that there were two classified types of T. gondii about ATP and ADP hydrolysis. The most virulent strain (RH) and avirulent strain (Fukaya) were classified in a type with higher ATPase than ADPase activities. Two virulent strains (C56, Beverley) and an avirulent strain (ME49) were classified in the other type with the same activities of ATPase and ADPase.

Adenosine Diphosphate↗

PubMed1990

A possible pathogenesis for Blackfoot disease--effects of trivalent arsenic (As2O3) on cultured human umbilical vein endothelial cells.

Blackfoot disease (BFD) is an endemic peripheral vascular occlusive disease found among the inhabitants of the southwest coast of Taiwan. The clinical features of BFD are similar to those of Buerger's disease. Pathology shows arteriosclerosis obliterans and thromboangiitis obliterans. The high arsenic content of artesian well water in the area is regarded as the main causal factor of this disease. Therefore, the purpose of this study was to observe the toxic effects of various arsenic concentrations on cultured human umbilical vein endothelial cells (HUV-EC). The methods of this study included cell growth assay, 51Cr-release assay, and staining of Factor VIII related antigen (FVIII-RAg) and Ulex europaeus agglutinin I (UEA-I) binding sites of HUV-EC. The following data were obtained: 1) no obvious cytotoxicity in 51Cr-release assay; 2) inhibition of the synthesis of both FVIII-RAg and UEA-I binding sites when the arsenic concentration was above 100 ng/ml; 3) dose-dependent inhibition of growth of HUV-EC by any concentration of arsenic. At a higher concentration of more than 100 ng/ml, arsenic inhibited endothelial cell proliferation and glycoprotein synthesis, whereas it only inhibited the proliferation at a lower concentration of less than 50 ng/ml. It is suggested that arsenic, at both higher and lower concentrations, may damage endothelial cells. Such damage may play an important role in the pathogenesis of BFD.

Arsenic↗

PubMed1990

ICAM-1 and LFA-1 expressions in the lesional skin of annular erythema associated with Sjögren syndrome.

ICAM-1 and LFA-1 expression was studied in the lesional skin of ten cases of annular erythema associated with Sjögren syndrome. Most of the infiltrating mononuclear cells around blood vessels expressed LFA-1 in addition to its strong expression on vascular endothelial cells and focal expression on the epidermal basal cell layer in 3 cases. ICAM-1 expression on vascular endothelial cells was similar to LFA-1, although relatively focal and weak expression was observed on mononuclear cells. ICAM-1 expression on keratinocytes was focal and limited to the basal cell layer in annular erythema. These findings suggest that strong expression of ICAM-1 on endothelial cells but not keratinocytes and LFA-1 on mononuclear cells might play some role in the induction of skin lesions in annular erythema associated with Sjögren syndrome.

Adult↗

PubMed1990

Platelet calmodulin correlates with platelet turnover.

We measured the calmodulin content in platelets in 13 normal persons and in 62 patients with hematological diseases. The level of platelet calmodulin was higher in patients with idiopathic thrombocytopenic purpura (ITP), systemic lupus erythematosus, myeloproliferative disorders, acute leukemia in a recovery phase, aplastic anemia, thrombosis and hypersplenism as compared to the controls. Among the patients with ITP, calmodulin was lower in responders than in nonresponders and those at the initial diagnosis. We also measured the volume, life-span and aggregation of the platelets and demonstrated a significant relationship between the calmodulin level and the platelet volume, and a negative relationship between the calmodulin level and platelet life-span, there was no correlation between the calmodulin level and platelet aggregation. We thus conclude that platelet calmodulin is inversely correlated with platelet turnover.

Biomarkers↗

PubMed1990

Membrane-delimited stimulation of heart cell calcium current by beta-adrenergic signal-transducing Gs protein.

A severalfold increase in calcium current (ICa) is a signal feature of the maximal beta-adrenergic response of the heart. It is generally ascribed to enhanced adenosine 3',5'-cyclic monophosphate (cAMP)-dependent phosphorylation of calcium (Ca) channels after beta-receptor activation of the guanosine nucleotide-binding (G) protein Gs, and Gs activation of the adenylyl cyclase cascade. We blocked phosphorylation pathways in guinea pig cardiomyocytes to unmask other possible ICa-stimulatory modes. In blocked cells, ICa increased by approximately 50% during 1) beta-receptor activation of Gs, 2) intracellular activation of Gs, and 3) intracellular application of preactivated Gs, We conclude that fast, membrane-delimited Gs modulation participates in the physiological regulation of cardiac ICa.

Animals↗

PubMed1990

[Combination chemotherapy (modified CHOP-Bleo) in non-Hodgkin's lymphoma].

Twenty-six adults with advanced non-Hodgkin's lymphoma (73% in clinical stage IV) were treated with a combination of cyclophosphamide, hydroxyldaunorubicin, vincristine, prednisolone and bleomycin (modified CHOP-Bleo), from May 1978 to July 1987. Complete remission (CR) was obtained in 12 of 26 patients (46%). The median survival time was 19.5 months (2-77 + months), Median duration of CR was 30.5 months (2-76 + months). The survival of patients with diffuse lymphoma large cell type (DL) was better than those with other diffuse lymphomas. The 50% of patients with DL are projected to be free of disease. The survival of patients with clinical stage III was significantly better than those with clinical stage IV. Major complications during chemotherapy with modified CHOP-Bleo were myelosuppression, constipation and peripheral neuropathy. These toxicities were generally mild and well tolerated.

Adult↗

PubMed1990

[Long-term arterial infusion chemotherapy to the cancer patients].

Arterial infusion chemotherapy is an effective method for unresectable and recurrent cancer patients. But this method had some problems, in terms of efficacy, side effect and safety. Thus, we studied these problems in 33 patients. We inserted the tube into the proper hepatic artery in 25 cases and into the aorta in 8 cases, and used anticancer drugs, such as MMC, ADM and CDDP. In this study, no serial or severe side effects were noted. On the other hand, the obstruction of catheter and artery was found in a few cases. We encountered 2 cases of CR and 11 cases of PR. The effectiveness of this method is approximately 46.4%. These results suggested that long term arterial infusion chemotherapy for outpatients was a safe and effective method from the view point of quality of life in cancer patients.

Adult↗

PubMed1990

The effect of various treatments on composite materials in bonding with resin cements.

The present study investigated the influence of surface treatments of composite materials using 6% hydrofluoric acid or 2% acidulated phosphate fluoride, the influence of the application of a bonding agent to the surface, and the influence of incremental curing of composite materials on the shear bonding strength between composite materials and resin cements. These results were studied statistically by analyzing variances in three-way classification and by their contributory ratios. The effects of hydrofluoric acids or acidulated phosphate fluorides on the treated surfaces of composite materials, and also the interfaces between composite materials and resin cements were further examined by mean of scanning electron microscopy (SEM). Unlike the controls, surfaces of all specimens treated with hydrofluoric acid or fluoride revealed micro-porous surfaces, but the effect of the surface treatment on the bonding strength was not equal for all the composite materials tested. The application of a bonding agent influenced some composite material, but the incremental curing of composite materials had no influence on bonding with resin cements.

Acidulated Phosphate Fluoride↗

PubMed1990

[Effects of indomethacin on calcium release from cultured rat calvaria].

The bone-resorbing action of lipopolysaccharides (LPS) in vitro has unknown mechanism of action. In order to evaluate the effect of LPS on rat calvaria and the influence of LPS on the bone-resorbing activity of macrophages, the following experiments were conducted. The addition of macrophages 10(6)/ml to a culture system composed of rat calvaria increased calcium release from the cultured bone. Addition of macrophages 10(6)/ml preincubated with 10(-2) mg/ml LPS caused a more pronounced release of calcium from the cultured bone. Combined use of Indomethacin, a prostaglandin synthesis inhibitor, with macrophages and macrophages preincubated with LPS inhibited calcium release, suggesting a possible participation of prostaglandins in osteoclast mediated bone resorption.

Animals↗

PubMed1990

[Study on porcelain veneer restorations. 2. Influence of hydrofluoric acid on bonding strength at the porcelain-resin interface].

Recently, porcelain veneer restoratives have been introduced to the general practice, and their clinical performances have been confirmed through many longterm clinical investigations. It is expected that porcelain veneer restorations will perform successfully in esthetic, conservative and abhesive dentistry. It is an well known fact that the micro-mechanical bonding strength at the porcelain-resin interface which is achieved through the application of hydrofluoric acid to the porcelain surface is quite a strong bonding mechanism. However, there are very few studies reporting on the acid treatment of porcelain surfaces. The authors have been studying the influence of hydrofluoric acid on porcelain surfaces, and in our previous report we reported, the degrees of corroded porcelain treated with different concentrations of hydrofluoric acid for different durations of application. In the present study, shear bonding strength was measured between resin cements and porcelain surfaces treated with different concentrations (4, 6, 8%) of hydrofluoric acid and for different durations (1 to 24 min.), and the appropriate treatment of porcelain surfaces with regard to the bonding strength was determined. The results obtained were as follows. 1. As the treating time increased with any concentration (4, 6, 8%) of hydrofluoric acid, corrosion of the porcelain surface became more intense. Hardly any evidence of corrosion was observed on any porcelain surface treated for one minute, so it seems that the treatment of porcelain surfaces using 4 to 8% hydrofluoric acids should be continued for over three minutes. 2. Observation of the surface profile by SEM showed no significant differences between the surfaces treated for 3, 6, 12 and 24 minutes. 3. It was not clear as to how the differences of hydrofluoric acid concentrations (4, 6, 8%) plus the differences in the kinds of porcelain (Super Porcelain AAA, NORITAKE Co. Ltd., VMK 68, Vita Zahnfabrik Gmbh & Co., Cosmotech Porcelain, G-C Co. Ltd.) had affected the differences in the amount of corrosion. 4. Regarding to the shear bonding strength at the porcelain-resin cement interface, in comparison with control specimens which were only sandblasted, about all two to three times higher bonding strength were obtained in specimens treated with any concentration (4, 6, 8%) of hydrofluoric acids and for any duration between 3 to 24 minutes. Specimens treated for one minute were an exception.

Composite Resins↗

PubMed1990

[Study on the porcelain veneer restoration. 3. Effect of various treatments of porcelain surface on the bonding strength at porcelain-resin interface].

In a previous report, observations were made on the apporopriate concentrations of hydrofluoric acid and durations of application in treating porcelain surfaces to improve the bonding strength at the porcelain-resin interface. Particular concentrations and durations were found, such as 4%, 6 min. for Supper Porcelain AAA, 8%, 6 min. for VMK 68, and 6%, 3 min. for Cosmotech Porcelain, and it was clearly shown that hydrofluoric acid treatment was the most effective treatment for porcelain-resin micro-mechanical bonding. However, because of its strong corrosive action, the use of hydrofluoric acid is very dangerous, and it must be handled with extreme care even in the laboratory. Accordingly, there is a need to find a safer and more effective way of treating porcelain surfaces, particularly in the field of interoral repairs to fractured porcelain restoratives by means of porcelain-resin micro-mechanical bonding. In the present study, 2% acidulated phosphate fluoride (APF), which corrodes the surface of porcelain restoratives, PorceLock (PL), which is a 2.5% buffered hydrofluoric acid made by DenMat Co. and a 6% hydrofluoric acid (HF) preparations were applied to the surface of porcelain specimens and the resulting effects on treated porcelain surfaces were examined by means of SEM observations and shear bonding strength tests. The following results were obtained: 1. In comparison with control specimens which were not treated with any acids or fluoride, a much higher bonding strength at the porcelain-resin interface was obtained in the specimens treated with 2% APF, PL and 6% HF. 2. Regarding to SEM observations, both of the specimens treated 6% HF or PL showed extremely micro-porous surfaces.2+ surfaces of the

Acidulated Phosphate Fluoride↗

PubMed1990

Herpes simplex lymphadenitis. Report of two cases with review of the literature.

We report two cases of herpes simplex lymphadenitis without widespread organ involvement in a 60-year-old man and a 67-year-old woman. Their complaints were high fever and generalized erythema followed after few days by generalized lymphadenopathy. This report describes the findings obtained by light and electron microscopy, immunohistochemistry, and in situ hybridization. In both instances, Cowdry's type A intranuclear inclusion bodies were found in T-immunoblasts in the background of T-zone hyperplasia with focal necrosis. Electron microscopic investigation revealed intranuclear and cytoplasmic virus particles with characteristics of the herpes group. Immunohistochemical staining utilizing anti-herpes simplex virus (HSV) antibody was positive and in situ hybridization with HSV-DNA probe revealed positive signals in the nucleus and in the cytoplasm of T-immunoblasts. Although rare, HSV lymphadenitis in the absence of generalized infection can occur.

Aged↗

PubMed1990

[Bone marrow re-transplantation following a busulfan and cyclophosphamide regimen].

A 36-year-old man was diagnosed as having RAEB in 1986, and required blood transfusion regularly because of severe anemia. He received the first bone marrow transplantation following total-body irradiation and etoposide infusion in October 1987. He was found to be relapsed into RAEB on 106th day after BMT. And the second BMT was planned. According to the conditioning regimen of Tutschka, et al, we administrated busulfan and cyclophosphamide before re-transplantation. On 26th day after BMT, the WBC count exceeded 1,000/microliters and anemia was improved, while thrombocytopenia persisted until 50th day. Normal hematopoiesis in the bone marrow was confirmed on the 29th day. No severe side effect except for a little fevering and bleeding was found during the clinical course. Unfortunately he died of pneumonia following graft versus host disease on the 166th day after re-BMT. This new conditioning regimen is considered to be a choice for the high risk patients on re-transplantation.

Adult↗

PubMed1990

[Autoregulation of macular capillary blood flow evaluated by the blue field entoptic phenomenon].

Autoregulation of the macular capillary blood flow was investigated using a blue-field entoptoscope and OCVM suction cup system. The perfusion pressure was reduced by elevation of the intraocular pressure with a Langham's suction cup placed on the temporal sclera. The results showed that the autoregulatory response maintains the macular capillary blood flow velocity until the perfusion pressure is reduced to approximately 25 mmHg. The Closed-loop gain of the autoregulatory response functions at a perfusion pressure as low as approximately 10 mmHg, below which it did not work well.

Adult↗

PubMed1990

[Retinal ganglion cell topography during prenatal development].

A fundamental feature of the human visual system is nonuniform distribution of ganglion cells across the retinal surface. In adults, the density of ganglion cells peaks around the fovea and declines sharply towards the periphery, whereas in fetal retina it does not. In the fetal retina, the retinotopic map is dominated by nonuniform expansion and/or ganglion cell death. We examined how the numbers and distributions change according to the horizontal eccentricity from the foveola, using toluidine blue stained vertical sections of the human fetal retina (gestational age 32W and 40W). The vertical section of the fovea showed almost similar density at 32 weeks, 40 weeks and in adults. This fact suggested that the fundamental structure of the fovea is already established at 32W. In the nasal retina, the cellular density was higher than that in the temporal half at 32W, then markedly decreased at 40W and in adults. We assume that in the nasal retina, it is impossible to account for the cell decrease only with nonuniform expansion and that even after 32W ganglion cell death occurs. On the other hand, in the mid-temporal retina, the cellular density was almost similar at 32W, 40W and in adults. It suggested that in the mid-temporal retina, the topography is already established at 32W. In the peripheral temporal retina, the cellular density was relatively high at 32W and decreased at 40W and in adults. In this area, the topography is still changing. We assume that in the fetal retina, retinotopic map is dominated by several factors and the dominant factor differs according to stage and retinal area.

Cell Count↗

PubMed1990

Endoscopic measurement of gastric mucosal blood flow with special reference to the effect of sclerotherapy in patients with liver cirrhosis.

Gastric mucosal blood flow plays an important role as a background factor in the pathogenesis of acute gastric mucosal lesion. In this study, endoscopic measurement of regional gastric mucosal blood flow was performed on 41 patients with esophageal varices due to liver cirrhosis to ascertain the possible relations of this parameter to liver function, portal pressure, and acute gastric mucosal lesion. The effect of sclerotherapy and of esophageal transection on gastric mucosal blood flow were also investigated. Regional gastric mucosal blood flow in either the antrum or the corpus was significantly decreased in these patients, compared with normal controls. There was also a significant difference in gastric mucosal blood flow between two subgroups of patients, one with gastric mucosal lesions and the other without these lesions. Sclerosing therapy for esophageal varices tended to affect this parameter. Gastric mucosal blood flow had no significant correlation with portal pressure.

Adult↗

PubMed1990

[Usefulness of combining a immunological fecal occult blood test (latex method) with a chemical test (guaiac method)].

A combination tests, using the latex and guaiac methods, has been carried out in 123 patients with a gastrointestinal disease and in 38 controls. The latex method was positive in 8% of the 38 controls, in 84% of 32 colorectal carcinoma patients, in 42% of 24 colonic polyp patients, in 22% of 9 gastric carcinoma patients, and in 22% of gastric ulcer patients in an active phase of their illness, whereas the guaiac method was positive in 39%, 81%, 58%, 78%, and 89% in the same order, respectively. From the above, a combination of both methods was found useful for the screening of hemorrhage in the gastrointestinal tract.

Colonic Polyps↗

PubMed1990

[Electrophysiological diagnosis in ulnar nerve entrapment at elbow].

Using "inching technique" we recorded antidromic sensory nerve action potentials from the little finger and compound muscle action potentials from the abductor digiti minimi, first dorsal interosseous and flexor carpi ulnaris muscles in 30 entrapped ulnar nerves. In cubital tunnel syndrome, localized conduction delay occurred most commonly at a point 2 to 4 cm distal to the medial epicondyle. In other ulnar neuropathies, with the exception of cubitus valgus deformity, conduction block or delay was noted at a site just distal to the medial epicondyle. These conduction abnormalities were most commonly observed in the abductor digiti minimi and first dorsal interosseous. In contrast, conduction abnormality in tardy palsy secondary to the valgus deformity reflected mainly in the flexor carpi ulnaris. This method provides useful information in diagnosing the early involvement and precise localization of nerve entrapment, and differentiation of cubital tunnel syndrome from other ulnar nerve entrapment.

Action Potentials↗