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Biomedical subjects

H Hashimoto

Publications and source records attributed to H Hashimoto.

At least 937 records · Page 52Linked to original sources
PubMed1990

Quantitative chemical analysis of nickel-chromium dental casting alloys.

Twenty-nine brands of dental casting nickel-chromium alloys made in Japan for small castings were analyzed by electron probe X-ray microanalyzer. Nickel-chromium alloys for metal-ceramic application were composed primarily of nickel, chromium, and molybdenum with the exception of one brand. Of the nickel-chromium alloys for inlay, crown, and bridgework applications, 11 of the 22 alloys were up to the standard of the Ministry of Welfare specifications. And additive metal elements of these alloys were molybdenum, iron, copper, manganese, aluminum, silicon, tin, indium, silver, titanium, and gallium.

Chromium Alloys↗
PubMed1990

[Inducing effect of tumor necrosis factor-alpha on differentiation of U937 monocytic tumor cell line].

We used the human monocyte/macrophage-like tumor cell line U937 to examine whether tumor necrosis factor-alpha (TNF-alpha) induces differentiation of monocyte/macrophage progenitors. Incubation of these cells with recombinant human tumor necrosis factor-alpha (rhTNF-alpha) resulted in an increase in Fc rosette formation by the cells. RhTNF-alpha increased the rosette formation in dose- and culture time-dependent manners. And the highest Fc rosette formation was observed in culture medium supplemented with 10% serum. However, U937 cell growth was not inhibited by rhTNF-alpha. The stimulatory effect of rhTNF-alpha was completely inhibited when the factor and indomethacin (10(-6) M) were added simultaneously to the cells. Also, rhTNF-alpha increased NBT reducing activity of the cells. Additionally, rhTNF-alpha-treated U937 cells produced interleukin-1 in the cell density- and culture time-dependent fashions. These results demonstrate that rhTNF-alpha is a potent inducer of the differentiation of the monocyte/macrophage-like tumor cell line U937.

Cell Differentiation↗
PubMed1990

[Bond strength of dental luting cements to titanium castings].

This study compared the tensile bond strength of dental luting cements to the titanium castings with gold alloy (Type IV), 12% Au-Ag-Pd alloy and Ni-Cr alloy in dental clinical practice. In this experimental condition, the zinc phosphate cement did not adhere to any dental casting alloy tested. The tensile bond strength of polycarboxylate cement to the titanium castings was 96 kg/cm2, about two times as high as that gold alloy (Type IV). The tensile bond strength of the glass ionomer cement to titanium castings was 32 kg/cm2, about two times as high as that of dental precious alloys. The tensile bond strength of the adhesive resin cement to titanium castings was 220 kg/cm2, about three times as high as that of dental precious alloys.

Dental Alloys↗
PubMed1990

[Crystalline glass ceramics model teeth].

The feeling of hardness, stickiness and the rate of cutting during the preparation of a tooth were compared using an extracted tooth, melamine resin and crystalline glass ceramics model tooth (Bioram M) which are used in dental education and practice. Diamond burs were used with an air-turbine handpiece in this experiment. The results indicated that Bioram M had the desirable characteristics of a model tooth and there was a strong resemblance feeling of cutting between Bioram M and a natural vital tooth.

Ceramics↗
PubMed1990

[Studies on titanium casting. (1) Influence of the mold temperature on titanium castings].

Pure titanium and titanium alloys have excellent biocompatibility, excellent corrosion tarnish resistance, a quarter of the specific gravity of gold base alloys and suitable mechanical properties for dental clinical use. However, titanium has some undesirable characteristics. For example, it has a high melting temperature and chemical reactivity at high temperatures. The investigate influence of the mold temperature on castability and mechanical properties of the titanium castings was study. The castability was found to be good at various mold temperatures, but the higher the mold temperature during casting, the greater the adhesive phenomenon between titanium surface and the investment. From the EPMA observation of the surface layer on the titanium castings, an Si- rich layer whose thickness increased considerably with increasing temperature was observed. The Vickers hardness in the surface layer was greater than that in the inner part. At a higher mold temperature during casting the thickness of the high Vickers hardness layer was increased. There was a relationship between the Vickers hardness value and the thickness of Si rich layer. In the tensile strength test of titanium castings, elongation values decrease and tensile strength values increased with the rise in mold temperature.

Dental Alloys↗
PubMed1990

Effects of an aldose reductase inhibitor, ONO-2235, insulin and their combination on the altered responsiveness to the nerve stimulation and agonists of the isolated atria of diabetic rats.

To determine the effects of an aldose reductase inhibitor (ARI) on diabetes-induced cardiac autonomic nerves disturbance, we examined the effects of ONO-2235, an ARI, as well as insulin on the responsiveness to the nerve stimulation and agonists of the isolated atria of the streptozotocin-induced diabetic rats. Insulin, 4 U/animal/day, was administered s.c. for 4 weeks before the experiment and ARI (ONO-2235), 40 mg/kg/day, was administered p.o. 3 weeks before the experiment. The transmural nerve stimulation (TNS) of sympathetic nerves and parasympathetic nerve was performed in the presence of atropine and metoprolol plus prazocin, respectively. The positive chronotropic and the inotropic responses of the atria to sympathetic TNS and to norepinephrine decreased in the rats diabetic for 8 and 12 weeks. In the rats diabetic for 8 weeks, the insulin treatment restored completely both the positive chronotropic and the inotropic responses to sympathetic TNS, whereas the ARI treatment partially improved the positive chronotropic response and did not improve the positive inotropic response. In the rats diabetic for 12 weeks, the insulin treatment partially improved the positive chronotropic and the inotropic responses to sympathetic TNS, whereas the ARI treatment only slightly improved the positive chronotropic response and did not improve the positive inotropic response to TNS. The combination treatment with insulin and ARI restored completely both the positive chronotropic and the inotropic responses in the rats diabetic for 12 weeks. In rats diabetic for both 8 and 12 weeks, the decreased positive chronotropic and the inotropic responses to norepinephrine recovered completely with the insulin treatment, but did not with the ARI treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1990

Increases in alpha-but not beta-adrenoceptors in hypertrophied non-infarcted cardiac muscles from rats with chronic myocardial infarction.

The alteration in adrenoceptors in the hypertrophied right ventricle of the rats with myocardial infarction (Ml) was examined. The density of alpha-1-adrenoceptors increased in four and twelve week old Ml rats but not in one week old Ml rats. The beta-adrenoceptors did not significantly change. It is probable that the increased density of alpha-adrenoceptors may be one of the causes for the increased responsiveness to the alpha-adrenergic agonist in the hypertrophied cardiac muscles of Ml rats.

Animals↗
PubMed1990

p24 protein of a human T-lymphotropic virus type-I (HTLV-I) producing cell line (TCL-Kan) reacts with some normal pregnant women's sera.

Some HTLV-1 antibody carrying pregnant women, who are rated by the gelatin particle agglutination (PA) method, show no expression of HTLV-I antigen in their peripheral blood lymphocytes. Paying attention to this fact, the authors recently studied the reaction of the antibody contained in the PA-positive sera with the antigen protein used for the PA method. This study demonstrated that the protein responsible for non-specific reaction has a molecular weight of 24,000 and that the isoelectric point of this protein differs from that of HTLV-I specific protein.

Agglutination Tests↗
PubMed1990

[Studies on metabolic characteristics of cirrhotic rat hepatocytes using primary culture].

To assess the metabolic characteristics of cirrhotic hepatocytes, a primary culture of hepatocytes was established using rat liver induced cirrhosis by CCl4 administration. Using this system, cell responsiveness to different metabolic and excretory stimuli was investigated and compared with a primary culture of normal healthy rat hepatocytes. Cirrhotic hepatocytes showed reduced protein synthesis in response to insulin and reduced urea synthesis in response to glucagon. However, DNA synthesis stimulated by insulin and EGF was significantly enhanced in cirrhotic hepatocytes. No significant difference was observed in the fluorescein diacetate excretion rate. Cirrhotic hepatocytes showed impairment of antipyrine metabolism and conjugation and excretion of unconjugated bilirubin. These results suggest indirectly that cirrhotic hepatocytes may be less functionally mature than normal healthy hepatocytes.

Animals↗
PubMed1990

[The role of endothelium-derived contracting factor (EDCF) and endothelium-derived relaxing factor (EDRF) in the aorta of the rat: identification of EDCF].

The present experiment was performed to identify endothelium-derived contracting factor produced by acetylcholine stimulation in the aorta of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). The rings of the thoracic aorta were obtained from age-matched SHR and WKY, and changes in isometric tension were recorded. The relaxant responses to acetylcholine in the rings from SHR were significantly weaker than those obtained in WKY. The relaxant responses to acetylcholine were significantly enhanced by pretreatment with a cyclooxygenase-inhibitor (indomethacin) or thromboxane A2/prostaglandin H2 receptor antagonist (ONO-3708) both in the SHR and WKY rings. A thromboxane A2 synthetase inhibitor (OKY-046) did not affect the acetylcholine-induced relaxation in the rings from SHR or WKY. In the organ bath solution, following acetylcholine stimulation, prostaglandin E2 and 6-keto-prostaglandin F1 alpha concentrations increased, but prostaglandin F2 alpha and thromboxane B2 concentrations did not increase. Exogenous prostaglandin H2, a stable analogue of thromboxane A2 (STA2) and prostaglandin F2 alpha induced contractions of the SHR rings at a lower concentration than prostaglandin E2, prostaglandin D2 and prostaglandin I2. These contractile responses to various prostaglandins were markedly inhibited by pretreatment with ONO-3708. A prostacyclin synthetase inhibitor did not affect the relaxant responses to acetylcholine in the SHR rings. These results show that endothelium-derived contracting factor is produced and released by acetylcholine stimulation not only in the aorta of SHR but also in that of WKY. The results also suggest that prostaglandin H2, a precursor of the released prostaglandins, is a strong candidate for endothelium-derived contracting factor produced by acetylcholine stimulation.

Animals↗
PubMed1990

Bednar tumor (pigmented dermatofibrosarcoma protuberans). An analysis of six cases.

Six cases of Bednar tumor were analyzed clinicopathologically along with a review of 39 published cases. The findings were then compared with data on 44 cases of ordinary dermatofibrosarcoma protuberans (DFSP) obtained from our files. The clinical manifestations of the patients and the anatomic locations of the tumors were similar between the two categories, but the rate of recurrence was lower in cases of Bednar tumor. The histologic pattern of Bednar tumor was indistinguishable from ordinary DFSP except for scattered melanosome-containing cells. Ultrastructural and immunohistochemical examinations showed no evidence of neuroectodermal differentiation of dominant spindle-shaped cells in Bednar tumor, supporting a fibroblastic line of differentiation. The origin and pathogenesis of the melanosome-containing cells were considered. These cells failed to react with HMB-45, a melanoma-specific antibody, and the large majority of melanosomes present were mature or at Stage IV, plus a few immature ones at Stage II. These pigmented cells do not appear to be neoplastic, and cannot be used as proof to indicate that Bednar tumor is a neuroectodermal neoplasm.

Adolescent↗
PubMed1990

Beneficial effects of a new 5-lipoxygenase inhibitor on occlusion- and occlusion-reperfusion-induced myocardial injury.

Effects of a new 5-lipoxygenase inhibitor TZI-41127 (2-(4-hydroxy-3,5-dimethylphenyl)-5-methoxy-3-methylindole) on occlusion- and occlusion-reperfusion-induced myocardial injury were examined in rats and dogs. The occlusion-reperfusion-induced myocardial injury was produced by the occlusion of the left anterior descending (LAD) coronary artery for 90 min following 22 h reperfusion in Beagle dogs. The drug was orally administered twice in a dose of 30 mg/kg. The first administration was 2 h before the occlusion and the second one was 1 h after the start of the occlusion. Eighteen dogs were divided into two groups. Nine were for control which were administered the vehicle, and the other were for the drug treatment. One animal of each group died because of ventricular fibrillation. The risk area and the infarct area were measured 22 h after reperfusion. The risk area as percent of total ventricle was not different between the two groups. However, the infarct area as percent of the risk area was significantly less in the drug-treated group. Although the ventricular arrhythmias immediately after the reperfusion were not prevented by the drug treatment, the ventricular arrhythmias 22 h after the reperfusion were significantly less in the drug-treated group. The arterial blood pressure, the heart rate and the double product were not significantly different between the two groups. The infarct size induced by LAD occlusion in rats was also reduced by the pretreatment with TZI-41127. Thus, TZI-41127 has beneficial effects on occlusion- and occlusion-reperfusion-induced myocardial injury.

Animals↗
PubMed1990

Clinical significance of IgG anti-Sm antibodies in patients with systemic lupus erythematosus.

Free Sm was purified by gel filtration and anti-Sm affinity chromatography. Using this purified antigen, an ELISA for anti-Sm was performed. Three hundred and fifty patients with various rheumatic diseases were studied with respect to immunoglobulin classes of anti-Sm by ELISA. A high frequency of IgG anti-Sm was specifically detected in patients with systemic lupus erythematosus (SLE), but IgA and IgM anti-Sm showed a low frequency and also was detected in other diseases. In patients with SLE, anti-Sm significantly correlated with lung fibrosis and pericarditis. In our longitudinal study, there were increases in titer of IgG anti-Sm preceding central nervous system exacerbation and serositis. IgG anti-Sm was found to be not only a diagnostic marker but also a reliable measure of disease activity in SLE.

Adolescent↗