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E Suzuki

Publications and source records attributed to E Suzuki.

At least 361 records · Page 20Linked to original sources
PubMed1990

Two pharmacologically distinct alpha 1-adrenoceptor subtypes in the contraction of rabbit aorta: each subtype couples with a different Ca2+ signalling mechanism and plays a different physiological role.

Using the alpha 1-adrenoceptor subtype-selective antagonists chlorethylclonidine (CEC), WB4101, and 5-methyl-urapidil, we have examined the possible heterogeneity in the alpha 1-adrenoceptor populations in rabbit aorta. The alpha 1-adrenoceptor alkylating agent CEC selectively inhibited the phasic component of the norepinephrine-induced contractile response, with little effect on the tonic component. The alpha 1-adrenoceptor occupancy-response relationship defined by the phenoxybenzamine inactivation method was rectangular hyperbolic for the tonic response, whereas that for the phasic response was linear, indicating the different degree of receptor reserve for the two responses. Radioligand binding studies with the nonselective alpha 1-adrenoceptor antagonist radioligand 125I-BE2254 showed that 73-87% of the binding sites in rabbit aorta are CEC sensitive and they are predominantly low affinity sites both for WB4101 (pKd = 8.1) and for 5-methylurapidil (pKd = 7.1). Moreover, alpha 1-adrenoceptor-mediated phosphatidylinositol (PI) hydrolysis was CEC sensitive, and fractional inactivation of alpha 1 receptors with CEC showed equivalent increments in the reduction of PI hydrolysis and phasic contractile response, suggesting that both responses are linearly related to the CEC-sensitive receptor sites. The Schild plots for the competitive antagonists WB4101 and 5-methyl-urapidil against alpha 1a-adrenoceptor-selective agonist methoxamine-induced contraction were linear and had slopes not significantly different from unity, with a pA2 of 9.07 +/- 0.07 (n = 5) for WB4101 and 9.09 +/- 0.05 (n = 3) for 5-methyl-urapidil. However, the Schilod plots for these antagonists against norepinephrine were curvilinear. Computer-assisted analysis of these curvilinear Schild plots in a two-receptor system indicated that alpha 1-adrenoceptor populations responsible for the constrictive response are predominantly (approximately 80-90%) low affinity sites for the two antagonists (pKd approximately 8.1 for WB4101 and pKd approximately 7.1 for 5-methyl-urapidil) and a small population (approximately 10-20%) are high affinity sites (pKd approximately 9.1 for both WB4101 and 5-methyl-urapidil), which was in good agreement with radioligand binding studies.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1990

Regulation of DNA primase activity by phosphorylation of histone-H1 in regenerating rat liver.

The biological importance of histone H1 was investigated in relation to the cell cycle using liver regeneration in rat. Histone H1 was extracted from the regenerating rat liver at various intervals after partial hepatectomy and the number of phosphate residues was measured. The inhibitory effect of the extracted histone H1 on DNA primase was assayed. The activities of DNA polymerase-alpha, DNA primase and DNA synthesis were also determined in the regenerating rat liver. It was found that: 1) phosphate residue in histone H1 from normal rat liver was between 2-3 mol/mol of histone H1. 2) The number of phosphate residues did not change for the first 16h after partial hepatectomy. 3) A dramatic sudden increase of phosphate residues was detected at 18h after partial hepatectomy. 4) The high levels of phosphate residues remained constant thereafter up to 50h. 5) DNA primase activity was less inhibited by highly phosphorylated than by slightly phosphorylated histone H1. It seems probable that phosphorylation of histone H1 is needed for the releasing of DNA primase activity from its inhibited state, which would start DNA synthesis together with DNA polymerase-alpha.

Animals↗
PubMed1990

[The direct tensile test of composite resins using the small specimen--effect of the preparation of specimen, the size of specimen and the testing condition on the tensile properties].

The direct tensile test of composite resins using the specimen with the gauge length 10 mm has been developed by authors. In this study smaller specimens with the gauge length 5 mm and 2 mm were also investigated. As the gauge length became smaller, tensile properties such as the proportional limit, the proof stress, and the tensile strength showed the tendency to become higher. The effect of strain rate on the tensile properties appeared clearly when using the specimen with the gauge length 2 mm. The small specimen was found to have many advantages for the preparation, the cost of material and the handling during the tensile test.

Composite Resins↗
PubMed1990

[Automatic polishing of dental prostheses. 1. Development of a centrifugal barrel finishing apparatus].

A centrifugal barrel finishing apparatus with a variable turn table rotational speed (250-1,000 rpm) was newly developed and barrel finishing of Ni-Cr casting plates (10 x 10 x 2 mm) was performed using alumina base chips. When using the sample with a mirror face the amount of polishing and the surface roughness increased and the surface gloss decreased with the increase in rotation speed. A high rotational speed was useful for coarse polishing and low rotational speed was useful for fine polishing. The continuous barrel polishing was trially performed using the sample prepared by the carborundum wheel under variable rotational speed. Automatic polishing to fine polishing could be done using this apparatus.

Dental Polishing↗
PubMed1990

[Sarcoidosis].

Explore the source record for details and available documents.

Bronchoalveolar Lavage Fluid↗
PubMed1990

Analysis of photoreceptor membrane turnover in a Drosophila visual mutant, rdgA, by electron microscope autoradiography.

A Drosophila visual mutant, rdgA, has photoreceptor cells whose rhabdomeres degenerate in several days after eclosion. Incorporations of 3H-amino acids, and 3H-mannose and 3H-glucosamine residues into the photoreceptive membranes were studied in newly emerged rdgA mutant flies by electron microscope autoradiography. The amount of 3H-amino acids incorporated in rdgA rhabdomeres at 3 hr after the injection was about 50%, and that of 3H-sugar residues was about 20% of normal. Together with our previous finding that degradative activity is low in rdgA cell bodies at this time, these data indicate that the supply of photoreceptive membrane proteins is defective in rdgA.

Amino Acids↗
PubMed1989

[Partial volume effect in MRI--a phantom study].

According to the direction and the thickness of the imaging slice in tomography, the border between the tissues becomes unclear (partial volume effect). In the present MRI experiment, we examined border area between fat and water components using phantom in order to investigate the partial volume effect in MRI. In spin echo sequences, the intensity of the border area showed a linear relationship with composition of fat and water. Whereas, in inversion recovery and field echo sequences, we found the parameters to produce an extremely low intensity area at the border region between fat and water. This low intensity area was explained by cancellation of NMR signals from fat and water due to the difference in the direction of magnetic vectors. Clinically, partial volume effect can cause of mis-evaluation of walls, small nodules, tumor capsules and the tumor invasion in the use of inversion recovery and field echo sequences.

Magnetic Resonance Imaging↗
PubMed1989

Direct measurement of K movement by 39K NMR in perfused rat mandibular salivary gland stimulated with acetylcholine.

The intracellular K content (Kin) of the isolated perfused rat mandibular gland was measured by 39K NMR spectroscopy at 25 degrees C, using an inversion recovery technique based on the fact that the spin-lattice (T1) relaxation of Kin is much faster than that of the extracellular K. Kin decreased by 30-34% of the resting level and reached a plateau level during secretion evoked by a sustained infusion of 1 mumol/l acetylcholine. Addition of 1 mmol/l ouabain decreased Kin by an additional 41% of the resting level. The K net flux to the blood and saliva was calculated from the K concentrations and flow rates of the effluent and the saliva. At an initial stage of secretion the gland lost K to the vascular side at a rate of 12.6 +/- 1.8 mumol/g-min (mean +/- SEM, n = 7). During sustained secretion, the gland took K up from the vascular side at a rate of 3.3 +/- 0.7 mumol/g-min (n = 7), and the same amount of K was secreted into the saliva (4.7 +/- 1.1 at 5-10 min, 2.8 +/- 0.8 mumol/g-min at 20-30 min), resulting in no net K movement from the gland. Addition of 1 mmol/l ouabain stopped salivary secretion and caused a transient K release to the vascular side at a maximum rate of 12.8 +/- 1.1 mumol/g-min. Withdrawal of acetylcholine and ouabain induced K uptake from the vascular side (6.5 +/- 0.7 mumol/g-min) and the amount of K released was completely restored when Kin recovered completely.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1989

Renal vasoconstriction by the endothelial cell-derived peptide endothelin in spontaneously hypertensive rats.

The effects of endothelin on systemic and renal hemodynamics in anesthetized spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats were examined. Endothelin (500 ng i.v. +1,000 ng/hr per 300-g rat) elevated mean blood pressure by 13% (p less than 0.02) and decreased renal blood flow by 71% and glomerular filtration rate by 66% (both p less than 0.01), resulting in a 430% (p less than 0.05) increase in renal vascular resistance (RVR) in SHR. This rise in blood pressure was associated with a significant increase in hematocrit (+8%), but a decrease in urinary sodium excretion (-51%). This dose of endothelin reduced cardiac output by 40% (p less than 0.001) and brought about a 96% (p less than 0.01) rise in systemic vascular resistance (SVR). However, the SVR increase was significantly smaller than the RVR increase. These changes in systemic and renal hemodynamics were observed in a dose-dependent manner, and the degrees of change did not differ between the two strains. Additional infusion of atrial natriuretic peptide (0.33 microgram/kg/min) into SHR completely reversed the changes in blood pressure and renal hemodynamics caused by endothelin, resulting in pronounced natriuresis (+760%). The renal vascular casting study revealed that endothelin mainly constricted the arcuate and interlobular arteries, as well as afferent arterioles. These results suggest that endothelin may be involved in blood pressure and body fluid volume regulation through systemic and renal vasoconstriction.

Animals↗
PubMed1989

Effect of dietary alpha-linolenate/linoleate balance on collagen-induced platelet aggregation and serotonin release in rats.

Male Sprague-Dawley rats at 3 weeks of age were weaned to a diet supplemented either with perilla seed oil [alpha-linolenic acid (alpha-LnA)/linoleic acid (LA) = 3.66] or with safflower seed oil (alpha-LnA/LA less than 0.01) for 5-6 weeks. The eicosapentaenoic acid (EPA)/arachidonic acid (AA) ratio in platelet phospholipids was much higher in the perilla oil group than in the safflower oil group. Platelet aggregability determined turbidometrically varied greatly among individual animals, and the difference in platelet aggregability between the two dietary groups was relatively small when higher concentrations (15 and 20 micrograms/ml) of collagen were used. However, when platelet aggregability was determined as an all-or-none phenomenon at lower concentrations (7.5 and 10 micrograms/ml) of collagen, a very distinct difference was observed between the two dietary groups; aggregability was much lower in the perilla oil group than in the safflower oil group. Collagen-induced serotonin release from platelets was significantly reduced in the perilla oil group as compared with the safflower oil group. These results emphasize the importance of estimating aggregability at threshold concentrations of collagen and confirm that dietary manipulation of the essential fatty acid balance could be useful in reducing the thrombotic tendency.

Animals↗
PubMed1989

[Diurnal changes in colonic motility in conscious dogs].

Daily profile of colonic motor activity was observed in 10 conscious dogs by means of extraluminal force transducers. Each dog was implanted with a set of seven strain, gauges, one on the terminal ileum and the remaining six on the colon equidistantly. The colonic motor activity was basically composed of migrating and non-migrating motor complexes at all six recording sites. Each motor complex was characterized by a tonic contraction superimposed by rhythmic bursts of phasic contractions. During fasted period these motor complexes recurred at a mean interval of 36 min, and a mean duration was 7 to 12 min. Those motor complexes which migrated over at least three recording sites were defined as "migrating", 72% of those observed at the most proximal sites (n = 2680) were migrating, and the remaining 28% were non-migrating. Of those migrating motor complexes 90.4% migrated caudad (iso-peristalsis), while only 9.4% migrated orad (antiperistalsis). During postprandial period the colonic motor complexes at all recording sites uniformly increased their frequency with shorter intervals. Different from the small intestine, the contractile patterns were essentially the same as those of fasted period. The postprandial acceleration of the colonic motor complexes seems to be compatible with gastrocolic response.

Animals↗
PubMed1989

Effect of erythorbic acid administration on activities of drug metabolic enzyme and phosphatases in guinea pigs administered an adequate amount of ascorbic acid.

The effect of erythorbic acid (ErA) administration on activities of liver aniline hydroxylase, liver acid phosphatase, and serum alkaline phosphatase, and the content of liver cytochrome P-450 was studied to determine whether or not ErA would affect the availability of ascorbic acid (AsA) in normal and AsA-deficient guinea pigs. In experiment I, changes of the enzyme activities and liver cytochrome P-450 content in the guinea pigs administered AsA and/or ErA and sacrificed on days 4, 10, 16, and 30 were examined. Moreover, in experiment II, after 16 days of depletion of AsA, the guinea pigs were administered AsA and/or ErA. These animals were sacrificed on days 0, 4, and 20 of the repletion period, after which the activities of drug metabolic enzyme and phosphatases and content of cytochrome P-450 during recovery were observed. The enzyme activities and cytochrome P-450 content of AsA-supplemented guinea pigs were similar to those of ErA-supplemented animals and also similar to those of both AsA and ErA-supplemented guinea pigs throughout the experimental period. During the repletion of the AsA-depleted guinea pigs, there were no significant differences in these enzyme activities and cytochrome P-450 content among the animals administered AsA and/or ErA. These results suggested that ErA administration may not affect the AsA availability in the guinea pigs.

Acid Phosphatase↗
PubMed1989

Glycogen phosphorylase activation by two different alpha 1-adrenergic receptor subtypes: methoxamine selectively stimulates a putative alpha 1-adrenergic receptor subtype (alpha 1a) that couples with Ca2+ influx.

We compared the effects of methoxamine on alpha 1-adrenergic receptor-mediated phosphorylase activation in rat hepatocytes and rabbit aorta. Although methoxamine is a potent agonist in activating phosphorylase of rabbit aorta, it had little effect in rat hepatocytes. Using the phenoxybenzamine inactivation method, we found that the quantitative relationship between 125I-BE2254 (125I-BE) binding capacity and maximal norepinephrine-stimulated phosphorylase activation was nonlinear in rabbit aorta, whereas it was linear in rat hepatocytes. The potency of methoxamine in inhibiting specific 125I-BE binding is significantly (p less than 0.05) higher in rabbit aorta (Kd, 96.4 +/- 7.7 microM), compared with rat hepatocytes (Kd, 283 +/- 16 microM). However, these quantitative differences could not fully explain the blunted [Ca2+]c and phosphorylase responses to methoxamine in rat hepatocytes. Treatment with chlorethylclonidine dose dependently suppressed 125I-BE binding sites and norepinephrine-induced phosphorylase activation in rat hepatocytes, whereas in rabbit aorta it resulted in only a 31% decrease in 125I-BE binding sites, with little effect on phosphorylase activation. Furthermore, alpha 1-adrenergic receptor-mediated cellular events of phosphatidylinositol (PI) hydrolysis and phosphorylase activation were unaffected by the removal of extracellular Ca2+ in rat hepatocytes, whereas both responses were markedly attenuated in rabbit aorta. The results indicate that two different alpha 1-adrenergic receptor subtypes activate glycogen phosphorylase, through different mechanisms for increasing [Ca2+]c in the two systems. In rat hepatocytes, alpha 1 receptors are closely linked to PI hydrolysis and Ca2+ release from intracellular stores and cause phosphorylase activation. In rabbit aorta, on the other hand, activation of alpha 1 receptors increases [Ca2+]c by Ca2+ influx from the extracellular fluid as well as by Ca2+ release, and both PI hydrolysis and phosphorylase activation are caused mainly by the Ca2+ entry. Methoxamine interacts with both chlorethylclonidine-sensitive and -insensitive alpha 1 receptor subtypes but selectively stimulates the alpha 1 receptor subtype that closely couples with the Ca2+ influx.

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

[A case of hypersensitivity pneumonitis due to isocyanate (TDI)].

A 46-year-old man who had worked in a paint processing plast for over 29 years was admitted to our hospital with complaints of nocturnal dyspnea and dry cough. A chest X-ray film showed diffuse granular shadows in bilateral lungs. Pulmonary function tests revealed reduction of diffusing capacity and restrictive impairments. Hypersensitivity pneumonitis (HP) due to isocyanates was speculated from his occupational history and clinical course. Positive skin tests against TDI-HSA and MDI-HSA, precipitating antibody against TDI-HSA, and negative lymphocyte stimulating tests of peripheral blood and bronchoalveolar lavage fluid were also noticed. Environmental provocation test was positive. Histological findings of transbronchial lung biopsy specimens showed diffuse alveolitis and Masson body, but no granulomas. According to these results, the patient was diagnosed as HP due to TDI. Type III allergy of Gell-Coombs seems to participate in this case. The granulomatous lesion is seen less frequently in isocyanate-related HP than in HP induced by organic dusts, which suggests the difference in immunological and histological reactions between both types of HP.

Alveolitis, Extrinsic Allergic↗
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↗