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Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 703 records · Page 39Linked to original sources
PubMed1989

Protection against autonomic denervation following acute myocardial infarction by preconditioning ischemia.

To examine the effects of ischemic preconditioning on efferent autonomic responses following acute transmural myocardial ischemia/infarction (MI), the time course and extent of efferent sympathetic and vagal denervation were compared between control dogs that received a one-stage sustained coronary occlusion and preconditioned dogs that received four 5-minute coronary occlusions separated by 5 minutes of reperfusion before sustained occlusion. Effective refractory periods (ERP) basal and apical to MI were determined in the baseline state and during neural stimulation before and after preconditioning occlusions and 20, 60, 120, and 180 minutes after sustained occlusion by ligature ligation of diagonal branches of the left anterior descending coronary artery. In 10 control dogs with transmural MI, ERP shortening induced by bilateral ansae subclaviae stimulation (4-msec pulses, 2-4 Hz and 2-4 mA) was unchanged at basal sites but was attenuated at apical sites. Four of 40 apical test sites exhibited efferent sympathetic denervation (less than or equal to 2 msec shortening) 20 minutes after sustained occlusion. Thirteen of 40 apical sites became denervated during a 3-hour period. In 10 preconditioned dogs, ERP shortening at apical sites was unchanged after preconditioning occlusions and during the first 60 minutes of sustained ischemia but was attenuated at 120 minutes. Three of 40 apical test sites became denervated during a 3-hour period. The cumulative percentage of denervated apical test sites was significantly less in the preconditioned group compared with the control group (p = 0.006) despite a comparable degree of subepicardial involvement in the MI (8.2 +/- 1.0% vs. 8.4 +/- 1.4%, the ratio to the left ventricular circumference, mean +/- SEM). In 11 control dogs tested for efferent vagal response after MI, ERP prolongation induced by bilateral vagal stimulation (4-msec pulses, 20 Hz with current strength 0.05 mA greater than that required to produce asystole) was unchanged at basal sites, but was attenuated at apical sites, and five of 44 test sites exhibited denervation (less than or equal to 1 msec prolongation) 20 minutes after sustained coronary occlusion. Fourteen of 40 apical sites became denervated during a 3-hour period. In 10 preconditioned dogs, vagally induced ERP prolongation was unchanged both at basal and apical sites, and none of 36 apical test sites exhibited denervation after preconditioning and during a 3-hour period of sustained coronary occlusion (p less than 0.001 vs. control group) despite a comparable degree of subendocardial involvement in the MI (11.8 +/- 0.8% vs. 11.9 +/- 1.3%).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Modulation of cardiac autonomic neurotransmission by epicardial superfusion. Effects of hexamethonium and tetrodotoxin.

The heart contains superficial cardiac nerves whose effects may be modulated by pericardial fluid bathing the epicardium. We tested this hypothesis in open-chest dogs anesthetized with secobarbital. Oxygenated normal Tyrode's solution (NT) or NT containing hexamethonium, a ganglionic blocker (500 microM), or tetrodotoxin, a blocker of axonal neurotransmission (5 microM, TTX), was instilled into the pericardial cavity to superfuse the epicardium of the whole heart. During each superfusion, effective refractory period (ERP) was determined in deep intramyocardium (greater than or equal to 4 mm in depth from the epicardium) of anterior and posterior left ventricle and in the subendocardium of the right ventricle in the baseline state and during bilateral cervical vagal stimulation (VS) or ansae subclaviae stimulation (SS). Lengthening of ERP induced by VS during superfusion with NT (6.9 +/- 0.3 msec, mean +/- SEM, n = 36) was eliminated during subsequent superfusion with hexamethonium (0.9 +/- 0.5 msec, p less than 0.001). Hexamethonium also prevented sinus arrest induced by VS but did not affect shortening of ERP induced by SS (17.3 +/- 1.3 to 16.6 +/- 1.0 msec, n = 26). TTX suppressed VS-induced changes in ERP (6.3 +/- 0.3 to 1.5 +/- 0.5 msec, n = 32, p less than 0.001) and SS-induced changes in ERP (18.8 +/- 1.6 to 6.0 +/- 0.9 msec, n = 23, p less than 0.001) but did not affect changes in ERP induced by intravenous administration of norepinephrine or methacholine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Prostaglandins and progesterone secretion in the in vitro perfused pseudopregnant rabbit ovary.

The relationship between progesterone and prostaglandin (PG) secretion in the pseudopregnant rabbit corpus luteum was investigated using isolated in vitro perfused ovaries. Progesterone and PG secretion were measured on days 1, 11, and 18 of hCG-induced pseudopregnancy. The mean progesterone secretion increased significantly from days 1 to 11, and then decreased significantly by day 18. PG secretion was inversely correlated with progesterone secretion, suggesting that PG might inhibit progesterone secretion. To test this hypothesis, indomethacin, an inhibitor of PG secretion, was administered to intact rabbits from days 11-18 of pseudopregnancy and/or on day 18 ovaries were perfused in vitro with indomethacin. Indomethacin administered in vivo, in vitro, or both in vivo and in vitro significantly reduced PG secretion compared to that in controls, but did not affect progesterone secretion. In addition, perfusion of ovaries in vitro with PGF2 alpha did not alter progesterone secretion on either day 11 or day 18. Thus, although there is an inverse relationship between progesterone and PG secretion during pseudopregnancy, PGF2 alpha alone had no effect on progesterone secretion. These results question the hypothesis that PGF2 alpha alone is the luteolytic factor.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Isolation of galactosaminoglycan moiety (CO-N) from protein-bound polysaccharide of Cordyceps ophioglossoides and its effects against murine tumors.

A galactosaminoglycan moiety was obtained from an antitumor polysaccharide fraction (SN-C) isolated from Cordyceps ophioglossoides culture. SN-C was subjected to sonication, then a protein-bound galactosaminoglycan (CO-N) was isolated specifically by precipitation with 10% ammonium hydroxide. When given intraperitoneally to mice, CO-N inhibited the proliferation of sarcoma 180 cells inoculated into the peritoneal cavity and exhibited a marked life-prolonging effect against ascitic tumors such as Ehrlich carcinoma and IMC carcinoma. CO-N also showed an inhibitory effect against solid Ehrlich carcinoma when given intratumorally and significantly inhibited the growth of a syngeneic solid tumor (MM46 mammary carcinoma) upon intravenous administration at a low dose. CO-N showed a cytocidal effect against cultured cells of IMC and P388D1 in vitro. Flow cytometric analysis demonstrated that fluorescein isothiocyanate-CO-N binds to the surface of Ehrlich cells.

Animals↗
PubMed1989

The metabolism in vivo of 3 alpha, 5 beta-tetrahydroaldosterone in the guinea pig.

Analysis of urinary metabolites of [1, 2-3H]-3 alpha, 5 beta-tetrahydroaldosterone was performed in male guinea-pigs. Separation of urinary metabolites was carried out by means of DEAE-Sephadex A-25 column chromatography and four fractions (fraction A to fraction D) were detected. 46-50% of fraction A was extractable with ethyl acetate. When ethyl acetate extract was submitted to reversed phase high pressure liquid chromatography, a number of peaks were present and one of these peaks cochromatographed with 3 alpha, 5 beta-tetrahydroaldosterone. Fraction B, fraction C and fraction D were incubated with enzyme and the free steroid released was identified on the basis of retention time on reversed phase high pressure liquid chromatography. Thus, fraction B contained monoglucosiduronate of 3 alpha, 5 beta-tetrahydroaldosterone, whereas identification of fraction C was not successful. Fraction D was characterized as a monosulphate; 3 beta, 5 beta-tetrahydroaldosterone, 3 alpha, 5 beta-tetrahydroaldosterone and 3 beta, 5 alpha-tetrahydroaldosterone were identified as aglycones. It is probable that 3 beta, 5 alpha-tetrahydroaldosterone is converted from other tetrahydroisomers by intestinal bacteria of the guinea-pig, since mammalian tissues do not contain enzymes that introduce a double bond into ring A.

Aldosterone↗
PubMed1989

In-vivo and in-vitro determination of components of rabbit early pregnancy factors.

Two types of rabbit early pregnancy factor (EPF) components, prepared from the in-vitro perfused ovary and oviduct and from serum ammonium sulphate fractions, were investigated to elucidate the source of EPF production. The state of the animals, i.e. pregnant, pseudopregnant, unstimulated or platelet activating factor (PAF)-treated, and order of addition of the components to the assay lymphocytes were varied to characterize conditions of production and expression of EPF activity. Although each component alone had no EPF activity, combination of two components, i.e. ovary and oviduct components, or serum precipitate and supernatant components, expressed EPF activity. The oviduct and serum supernatant components were produced in pregnancy and pseudopregnancy but the ovary and serum precipitate components were produced only in pregnancy. The similarity of the production pattern and ability of the perfusate and serum components to yield EPF activity when combined suggests that they are similar or the same. The sources of stimulation of EPF production did not appear to affect component production because the activity produced by the perfused ovary and oviduct in pregnancy or in response to PAF stimulation appeared similar. Oviduct and supernatant components apparently bound directly to lymphocytes. These results suggest that EPF components are produced in the ovary and oviduct individually and that the combination of the two components expresses EPF activity in the rabbit.

Animals↗
PubMed1989

The effect of ofloxacin on experimental periodontitis in hamsters infected with Actinomyces viscosus ATCC 15987.

Syrian hamsters were infected with Actinomyces viscosus ATCC 15987 by inoculation into the oral cavity to induce experimental periodontitis. The effect of an antibiotic, ofloxacin (OFLX), on the experimental periodontitis was examined. In Group A, OFLX gel was applied daily to the gingival mucosa, 2 weeks after bacterial inoculation. Groups B and C were an infected control and a noninfected control, respectively. The hamsters in these three groups were fed a powdered high-sucrose diet. The hamsters in Group D, also a noninfected group, were fed an ordinary solid diet. Salivary occult blood test, evaluation of gingival and plaque index, measurement of alveolar bone loss, bacterial examination, and histological observation were performed 11 weeks after infection. Group B exhibited significantly higher levels of gingival index, plaque index, and alveolar bone loss than the noninfected controls. Severe inflammation of the gingivae, formation of gingival pockets, migration of many inflammatory cells, and obvious bone loss were also observed in Group B. However, these inflammatory changes were milder in Group A, which was treated with OFLX.

Actinomyces↗
PubMed1989

[Antigen presenting cells and T lymphocytes in the induction phase of contact hypersensitivity].

When a sensitizing substance that induces contact hypersensitivity, fluorescein isothiocyanate (FITC), was painted on abdominal skin of mice, FITC+ cells appeared in the inguinal lymph node after 24 hours. The FITC+ cell in the lymph node was relatively large in size, and it did not appear to be a T lymphocyte. When FITC was painted on either murine tail skin or skin pre-treated by tape stripping, the number of FITC+ cells in the inguinal lymph node was significantly less than that in the positive control. In the mesenteric lymph nodes, which have a different lymph flow from that of the skin regional lymph node, FITC+ cells did not increase in number, and the few FITC+ cells were not significantly different in number among above-mentioned experimental systems. In the inguinal lymph nodes on the 4th day after painting of picryl chloride (PCl) on the abdominal skin of mice, L3T4+ cells, which expressed an interleukin 2 receptor (IL-2R), increased in number. On the other hand, when PCl was painted on either tail skin or skin treated by tape stripping, L3T4+ IL-2R+ cells did not increase in the skin regional lymph nodes. The number of L3T4+ IL-2R+ cells in the mesenteric lymph nodes did not increase in any of the experimental systems mentioned above. These results suggest some relationship between antigen presenting cells and T lymphocytes, as well as one between the skin and the regional lymph nodes, in an induction phase of sensitization in contact hypersensitivity.

Animals↗
PubMed1989

[Polishing of titanium prosthetics (Part 6). The chemical polishing baths containing hydrofluoric acid and nitric acid].

Titanium was polished using several chemical polishing baths containing different ratios of hydrofluoric acid and nitric acid. The meltage, surface roughness, and surface texture of titanium samples after chemical polishing were affected by the ratio of hydrofluoric acid and nitric acid. Generally the meltage increased and surface roughness decreased when the mole concentration of hydrofluoric acid was high and that of nitric acid was low. For example the chemical polishing bath containing 5 mole hydrofluoric acid and 5 mole nitric acid improved the surface texture in one minute, but SEM observation revealed a partially rough surface caused by the excessive solution. The chemical polishing bath containing 1 mole hydrofluoric acid and 5 mole nitric acid did not improve the surface texture in a short time because of low solubility, but improved the surface texture gradually with the extension of the immersion time and a good surface texture was observed by SEM. The chemical polishing using the chemical polishing bath with low solubility and immersion of the prosthetics for a rather long time were considered useful procedures to obtain a smooth surface of titanium prosthetics while maintaining their accuracy.

Dental Polishing↗
PubMed1989

Distribution of Gm allotypes among the three populations of the Miyako Islands in Okinawa.

Serum samples from 738 unrelated individuals of three populations in the Miyako Islands were tested for twelve Gm allotypes to investigate the variability of phenotypes and haplotypes. Nine phenotypes observed in these populations as well as mainland Japanese could be explained by the presence of the four Gm haplotypes, ag, axg, ab3st, and afb1b3. A good agreement was obtained in the samples of each populations between the observed and expected frequencies on the basis of the Hardy-Weinberg equilibrium of phenotypes. These populations showed remarkable heterogeneities with one another on the basis of Gm haplotype frequency analysis. Moreover they exhibited no homogeneities with the Ryukyuans nor with the mainland Japanese. Homogeneity was found between the Ainu and the people in Ueno village but not in the other two locations. However, Gm xg haplotype, only detected in the Ainu, was not found in Ueno. These may imply a racial relationship between the Ainu and the inhabitants in Miyako in the remote past. However, there is no certainty that both of Ainu and the people in Ueno derived from the same origin, or that genetic drift due to endogamy in this village took place. The Gm phenotype and haplotype frequencies observed in Miyako show that they belong to the northern mongoloid group characterized by a high frequency of Gm ag and an extremely low frequency of Gm afb1b3. It is therefore reasonable to assume that they came from northern Asia as well as mainland Japanese.

Asian People↗
PubMed1989

Fibrinogen Sapporo: dysfibrinogenemia characterized by the replacement of A alpha arginine-16 by histidine resulting in the delayed release of fibrinopeptide A by thrombin.

Congenital dysfibrinogenemia was found in a 60-year-old asymptomatic female and her daughter. Purified fibrinogen derived from the propositus, apparently a heterozygote for the abnormality, characteristically showed delayed but complete release of fibrinopeptide A upon digestion with thrombin but its defective release by Ancrod, a snake venom enzyme, from half of her fibrinogen molecules. This congenital dysfibrinogenemia with an A alpha arginine (Arg) to histidine (His) substitution was tentatively designated as fibrinogen Sapporo. Although this type of abnormal fibrinogen had been identified among Caucasians, no such cases have so far been reported in Japan.

Female↗
PubMed1989

[Polycythemia vera with an inhibitor against factor XII].

A case of polycythemia vera with an inhibitor against factor XII was reported. A 60-year-old female was admitted to Hokkaido University School Hospital because of erythrocytosis and hepatosplenomegaly. The hemoglobin was 22.5 g/dl and white cell count was 9,500/microliters without immature cells. The platelet count was 484,000/microliters. Bone marrow specimens showed marked hypercellularity. Philadelphia chromosome was not found on chromosome analysis. She was diagnosed as polycythemia vera according to the criteria of polycythemia Vera Study Group. Activity of factor XII was found to be decreased on the initial examination, but she had no personal and familial history of bleeding. In order to clarify the cause of decreased activity of factor XII, her plasma was mixed with normal plasma, and then examined PTT using factor XII deficient plasma. Her plasma mixed with equivalent normal plasma did not show the correction of prolonged PTT. It was suggested that an inhibitor of her plasma was included in the IgG fraction using gel chromatography. The patient was treated with phlebotomy and administration of N4-palmitoyl (1- -D-arabinofurasyl) cytosine (derivative of cytosine arabinoside; PLAC) 200 mg/day and Busulfan (1 mg/day). Factor XII was not corrected by phlebotomy, but corrected gradually by administration of PLAC and Busulfan.

Factor XII↗
PubMed1989

[Chemical durability of composite resins].

To evaluate their chemical durability, samples of posterior composite resins were stored in NaOH (0.1 mol, 1 mol), HCl (0.1 mol, 1 mol), acetone (99%), and distilled water at 37 degrees C for a week and subjected to the direct tensile test, measurement of surface roughness and SEM observation. NaOH caused the degradation of composite resins, decrease of tensile strength and increase of surface roughness. The SEM photograph of fractured surface of tensile specimens revealed the degradation zone under the surface. It was considered that NaOH caused the hydrolysis of silan coupling of composite resins. HCl also caused the degradation of composite resins, but some resins showed the durability in this condition. More examination is needed to clarify the mechanism of degradation. Acetone caused the degradation of matrix resin and some composite resins. It was considered to dissolve the low degree of polymerized matrix resin of composite resins. Immersion in chemicals of composite resins was thought to be useful to evaluate the chemical durability and to accelerate the degradation in water.

Composite Resins↗