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Biomedical subjects

T Okada

Publications and source records attributed to T Okada.

At least 595 records · Page 33Linked to original sources
PubMed1993

Functionally distinct endothelin B receptors in vascular endothelium and smooth muscle.

IRL 1620 (Suc-[Glu9,Ala11,15]-ET-1 (8-21)) (0.1 nM - 1 microM), a novel ETB-selective endothelin (ET) agonist, produced endothelium-dependent relaxations in precontracted rabbit mesenteric artery (2 nM, EC50) and endothelium-independent contractions in porcine coronary artery (18 nM, EC50). ET-3 (0.1 nM-10 nM) produced qualitatively similar responses in the two tissues. The maximal contractions induced by IRL 1620 or ET-3 were substantially smaller (< 20%) than that produced by ET-1. BQ-123 (1 microM), an ETA receptor antagonist, inhibited responses to ET-1 without affecting IRL 1620- or ET-3-induced responses in either tissue. Thus functionally distinct ETB receptors mediating vasodilator and vasoconstrictor effects are located on the vascular endothelium and smooth muscle, respectively. The overall effect of ETB receptor activation on vascular tone is tissue-specific and presumably reflects differing receptor distribution at the two sites.

Animals↗
PubMed1993

ETB receptor antagonist, IRL 1038, selectively inhibits the endothelin-induced endothelium-dependent vascular relaxation.

In isolated rat aorta, endothelin-1 induced contractions at lower concentrations than endothelin-3. The contractile effects were augmented by removing the endothelium. In contrast, endothelium-1 and endothelin-3 at similar concentrations induced endothelium-dependent relaxation in norepinephrine-stimulated aorta. IRL 1038 ([Cys11,Cys15]endothelin-1(11-21); 3 microM) augmented the contractile effects of endothelins only in the presence of the endothelium. IRL 1038 (0.3-3 microM) inhibited the endothelium-dependent relaxation induced by endothelins but not by carbachol. IRL 1038 itself did not change muscle tension. These results suggest that IRL 1038 is a novel antagonist of the ETB receptor responsible for the release of relaxing factor from the vascular endothelium.

Animals↗
PubMed1993

Effects of maternal bilateral ureteral ligation on fetal development of kidney in rats: morphometrical changes in glomerular components.

Development of the glomerulus in fetal kidney was studied morphometrically following ligation of both ureters of pregnant rats. The ligation was performed on days 17, 19, and 21 of gestation, and autopsy was done 24 hr after each operation. The percentage volumes of the five glomerular components (epithelial cells, capillary, mesangium, glomerular basement membrane, and Bowman's space) were determined by point counting, and the surface area of glomerular basement membrane per unit volume of glomerulus was calculated by intercept counting. On fetal days 18, 20, and 22, percentage volume of Bowman's space in the fetuses from the ligated mothers was significantly smaller than that in the fetuses from sham-ligated mothers. On fetal days 20 and 22, surface area of glomerular basement membrane and glomerular capillary length per unit volume of glomerulus and percentage of glomerular capillary volume in the fetuses from the ligated mothers were significantly larger than those in the fetuses from sham-ligated mothers. These results suggest that maternal bilateral ureteral ligation induces an increase in filtration area of glomerulus in fetal kidney when the fetal kidney is functional.

Animals↗
PubMed1993

Porous collagen sponge for esophageal replacement.

A new artificial esophagus with a bilayered structure made of porous collagen sponge and silicone was studied. The concept of this study was not to replace an esophageal defect permanently with prosthesis but to promote tissue regeneration by collagen. Five centimeters of cervical esophagus were replaced by this artificial esophagus in 19 adult mongrel dogs. Two weeks after implantation, the collagen sponge was replaced by autologous tissue and regeneration of the "neoesophagus" was observed in all animals. The inner surface of the neoesophagus was covered with mature mucosal epithelium similar to the intact esophagus 4-5 weeks after implantation. The replacement site was not complicated by infection, anastomotic leakage, or exuberant granulation tissue development on the luminal surface. In a long-term survival study, animals showed moderate-grade stenosis but could take normal feed orally and with no clinical problems observed.

Animals↗
PubMed1993

Tissue reactions to subcutaneously implanted, surface-modified silicones.

To evaluate the influence of surface properties on tissue reactions, the surface of a medical-grade silicone elastomer was modified without changing the bulk properties. Surface modifications employed were oxidation by corona discharge in air, graft polymerization of water-soluble monomers, coating a polysaccharide through polyion complex formation, and covalent immobilization of cell-adhesive proteins. Surface-modified silicone sheets were implanted in the subcutaneous tissue of rats, and tissue reactions such as infiltration of inflammatory cells, appearance of foreign-body giant cells, and collagenous capsule formation were studied. It was found that the thickness of collagenous capsules formed after 16 weeks' implantation was in the range of 85-95 microns for the nontreated ones and all the modified silicones except the acrylic acid-grafted and the collagen-immobilized silicones.

Animals↗
PubMed1993

Identification of new cystathionine mono-oxo acids, S-(3-oxo-3-carboxy-n-propyl) cysteine and S-(2-oxo-2-carboxyethyl) homocysteine, in the urine of a patient with cystathioninuria.

Novel cystathionine mono-oxo acids, S-(3-oxo-3-carboxy-n-propyl) cysteine and S-(2-oxo-2-carboxyethyl) homocysteine, and cyclic amino acid, cystathionine ketimine, have been detected in the urine of a patient with cystathioninuria using liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface system and an amino acid analyzer. To determine these cystathionine mono-oxo acids and cystathionine ketimine we took advantage of the selective absorbance at 380 nm of the phenylisothiocyanate-ketimine interaction product. The total concentrations of these compounds found in the urine samples of a cystathioninuric patient and six healthy subjects were respectively 3611.3 and 148.4 micrograms +/- 35.9/g of creatinine. The cystathioninuric patient excreted 20 times more cystathionine mono-oxo acids in the urine than healthy subjects.

Amino Acid Metabolism, Inborn Errors↗
PubMed1993

Aurothiolates inhibit HIV-1 infectivity by gold(I) ligand exchange with a component of the virion surface.

Aurothioglucose and aurothiomalate have anti-HIV-1 activity in vitro. Antiviral activity requires the formation of a reactive intermediate with a molar equivalent amount of a thiol ligand. This activates gold(I) ligand exchange between the reactive species bis(thiolato)gold(I) and acidic thiol groups exposed on the surface of proteins. Bis(thioglucose)gold(I) (bisAuTG) which is formed by the reaction of molar equivalent amounts of aurothioglucose and 1-thio-beta-D-glucose completely protected MT-4 and CEM cells against HIV-1NL4-3-induced cytopathogenicity. Although bisAuTG is an inhibitor of human immunodeficiency virus-1 (HIV-1) reverse transcriptase in a cell-free assay, its antiviral effect is due to modification of a surface component of the virion. The HIV-1 strain NL4-3 is 200-fold more sensitive to inhibition of infectivity by bisAuTG than are the strains MN, RF, and SF-2. HIV-1NL4-3 has a unique cysteine residue close to the amino terminus of its gp41 envelope glycoprotein (residue 532 of gp160) which we hypothesize is the target of bisAuTG binding. Mutation of that residue alters HIV-1NL4-3 infectivity and dominantly suppresses virus assembly when coexpressed with the wild-type NL4-3 genome. We show that bisAuTG treatment releases gp120 from the surface of cells expressing wild-type HIV-1NL4-3 envelope glycoprotein, but it does not release gp120 if Cys532 is mutationally altered to Ala. Thus, the antiviral effect of bisAuTG on HIV-1NL4-3 is due to an effect on the association of gp120 with gp41.

Amino Acid Sequence↗
PubMed1993

The effect of reactive oxygen species on the biosynthesis of collagen and glycosaminoglycans in cultured human dermal fibroblasts.

The purpose of this study was to evaluate the possibility that the biological changes observed in connective tissue matrix components of photoaging skin may be induced by an alteration of biosynthesis in fibroblasts damaged by reactive oxygen species (ROS). We investigated the effect of ROS induced by xanthine and the xanthine oxidase system on the biosynthesis of connective tissue matrix components, collagen and glucosaminoglycans (GAGs) in cultured human dermal fibroblasts. ROS decreased collagen production and increased GAGs synthesis. Interestingly, these changes were consistent with the biological alterations of connective tissue matrix components observed in photoaging skin. Moreover, catalase and alpha-tocopherol completely prevented the ROS-induced alterations of collagen and GAGs biosynthesis, whereas superoxide dismutase had no effect on the ROS-induced changes. These results suggest that ROS may be one of the factors which cause the biological changes of connective tissue matrix components observed in photoaging skin.

Catalase↗
PubMed1993

Identification of N-acetyl-alpha-aminoadipic acid in the urine of a patient with alpha-aminoadipic and alpha-ketoadipic aciduria.

A 3.5-year-old Japanese boy with a mild speech disturbance excreted a large amount of alpha-aminoadipic acid into the urine. The amino acid analysis using an amino acid analyser confirmed the presence of alpha-aminoadipic acid in both urine and plasma. We detected alpha-aminoadipic acid in the hydrolysate of the effluent and washwater fraction through cation exchange resin. This suggested the presence of acetylated derivatives and we identified N-acetyl-alpha-aminoadipic acid using liquid chromatography-atmospheric pressure ionization mass spectrometry (LC-API-MS). The concentrations of alpha-aminoadipic acid and N-acetyl-alpha-aminoadipic acid in the urine of a patient with alpha-aminoadipic aciduria were 376.9 nmol/mg creatinine and 18.1 nmol/mg creatinine, respectively. We also detected alpha-ketoadipic acid in the urine of this patient using LC-API-MS.

2-Aminoadipic Acid↗
PubMed1993

Coronary arterial lesions due to Kawasaki disease: selective coronary angiography in five cases with difficult-to-detect localized stenosis.

We report five cases of localized stenosis in coronary arterial lesions due to Kawasaki disease which were difficult to demonstrate by routine selective coronary angiography. Of these cases, three had localized stenosis overlapping the aneurysm, one had localized stenosis overlapping another adjacent branch, and the fifth had localized stenosis at the proximal left main trunk of the coronary artery. The reasons for difficulty in demonstrating the stenoses by routine study include: the localized stenosis was often superimposed on the aneurysm and/or the other adjacent branches, and the catheter was pushed into the inlet of the aneurysm on the proximal left main trunk. For a precise demonstration of a localized stenosis by selective coronary angiography, many angiograms from different perspectives should be taken. In addition, when a large aneurysm exists in the left main coronary artery, selective coronary angiography should be taken without pushing the catheter into the inlet of the aneurysm, and each frame of the cine coronary angiography should be carefully examined. Care should also be taken to compare with the initial view of the projection.

Child↗
PubMed1993

Carbamazepine-induced skin rash in children with epilepsy.

The clinical and epidemiological findings in children with epilepsy who experienced skin rashes induced by carbamazepine (CBZ) were prospectively evaluated. Thirty-three (9.9%) of 335 patients who received CBZ therapy experienced a skin rash. Seven had diffuse erythema, 13 miliary exanthema, 11 maculopapular or speckled reddish rash, 3 petechiae, and 2 mucocutaneous syndrome. A skin rash was more frequent in older children (over 6 years old). The skin rashes appeared soon after initiation of the therapy, i.e., from the 8th to 60th day (mean: 14.3 +/- 9.6 days) after the start of CBZ therapy and disappeared within a few days after discontinuation of the therapy. Haematological abnormalities (30.3%), such as leucocytopenia and thrombocytopenia, and hepatic dysfunction (27.3%) sometimes appeared concomitantly with the skin rash. CBZ is an effective and safe antiepileptic drug, but careful management is necessary on initiation of the therapy.

Adolescent↗
PubMed1993

Operative approaches for left-sided carinoplasty.

Carinoplasty was performed in 42 patients: 7 with wedge pneumonectomy, 15 with sleeve pneumonectomy, 14 with one-stoma-type carinal reconstruction, 5 with montage-type carinal reconstruction, and 1 other. Diagnoses in the 42 patients consisted of lung cancer in 31 (73.8%), tuberculous stenosis in 10 (23.8%), and tracheobronchial injury in 1 (2.4%). The thoracotomy was on the right side for lung cancer in 77.4% and on the left side for tuberculous stenosis in 80.0% (p < 0.01). Left-sided carinoplasty was performed in 14 patients using four approaches: midline thoracotomy in 1, left thoracotomy in 10, midline sternotomy and left thoracotomy in 2, and bilateral thoracotomies in 1. Left wedge or sleeve pneumonectomy, without right thoracotomy, could be done by midline sternotomy and left thoracotomy but with limited tracheal resection. Left one-stoma-type carinoplasty was undertaken, sacrificing one lobe, as an alternative to pneumonectomy, where an approach drawing the carina down to an aortopulmonary window was considered to be preferable to the drawing-up approach.

Anastomosis, Surgical↗
PubMed1993

A novel subtype of endothelin B receptor mediating contraction in swine pulmonary vein.

Effects of agonists and antagonists of endothelin (ET) receptors were examined in swine pulmonary artery and vein and in rabbit saphenous vein. ET-1, but not ETB receptor agonists, sarafotoxin S6c (STXc) and IRL 1620, induced contraction in pulmonary artery. This effect was inhibited by the ETA receptor antagonists, BQ-123 and FR139317, but not by the ETB receptor antagonist, IRL 1038. Pulmonary artery precontracted by norepinephrine was relaxed by ET-3 in an endothelium-dependent manner. This relaxation was inhibited by IRL 1038 but not by BQ-123. In pulmonary vein, ET-1, ET-3, STXc and IRL 1620 induced contractions at a similar concentration range. ET-1 induced contraction also in saphenous vein. These contractions were not inhibited by BQ-123, FR139317 or IRL 1038. These results suggest that the isopeptide-selective ETA receptor mediates contraction in swine pulmonary artery whereas the isopeptide-nonselective ETB receptor mediates release of endothelium-derived relaxing factor. In contrast, contractions in the veins may be mediated by a novel subtype of isopeptide-nonselective ETB receptor which is not inhibited by IRL 1038.

Animals↗
PubMed1993

Dissecting aneurysm of the anterior cerebral artery: report of two cases.

Two cases of spontaneous dissecting aneurysm localized to the anterior cerebral artery are reported. Both patients experienced severe headaches, followed by symptoms of cerebral ischemia. In the first case, the dissecting aneurysm showed an angiographic appearance resembling a saccular aneurysm of the anterior communicating artery, and the diagnosis of dissecting aneurysm was confirmed at operation. The second case was treated conservatively, and the diagnosis was reached by repeat angiographic studies.

Aortic Dissection↗
PubMed1993

Surface morphology and friction coefficient of various types of Foley catheter.

Urinary catheters are commonly used in chronic care facilities and geriatric homes. Problems associated with the catheters include encrustation, infection, physical trauma and inflammation. Many of these problems can be correlated to the catheter surface. Previous studies have dealt with problems associated with surface morphology and catheter composition and numerous catheter coatings have been developed to alter the surface including siliconized, Teflon and polyurethane hydrogel coatings. The hydrogel coating appears best, as it imparts a smooth, soft surface layer with lubricating properties. The paper describes a new poly(vinyl alcohol) hydrogel coating and compares its surface morphology and lubricity with other catheter coatings. Each catheter coating-type was examined by scanning electron microscopy for surface morphology. The new hydrogel coating was found to be smooth with no evidence of cracking. The apparent friction coefficient was used as an indication of surface lubricity. Friction measurement tests of the new hydrogen coating were run underwater and the friction coefficient was determined between the hydrated catheter surface and the hydrogel surface. The new hydrogel coating was found to have a high degree of lubricity in its hydrated state.

Equipment Failure↗
PubMed1993

Fetal mononuclear cells show a comparable capacity with maternal mononuclear cells to produce IL-8 in response to lipopolysaccharide in chorioamnionitis.

IL-8 is a chemotactic and activating cytokine for neutrophils which eliminate invading bacteria by releasing bactericidal metabolites. Cord blood mononuclear cells (CBMCs) obtained from neonates born to mothers with chorioamnionitis actively produced a significantly higher amount of IL-8 than those of neonates without chorioamnionitis, suggesting that the mononuclear cells of fetuses with chorioamnionitis had been activated in utero. As lipopolysaccharide (LPS) can often be detected in the uteroplacental space in chorioamnionitis, the LPS-mediated activation mechanism of neonatal mononuclear cells was analyzed in vitro to produce IL-8. Neonatal mononuclear cells stimulated with LPS increased IL-8 production in a time- and dose-dependent manner. The ability of term or preterm neonatal mononuclear cells to produce IL-8 was comparable with that of adult (maternal) mononuclear cells, suggesting functional maturity of the neonatal or fetal mononuclear cells to produce IL-8. However, IL-8 production by neonatal CBMCs was down-regulated by dexamethasone, a glucocorticoid which is clinically administered to mothers to promote fetal lung maturity in preterm delivery. Our present study revealed a regulatory mechanism of fetal IL-8 production, suggesting that functionally mature fetal mononuclear cells produce IL-8 in response to LPS in chorioamnionitis and activate the fetal defense mechanism against infection.

Cells, Cultured↗
PubMed1993

Binding affinities of mometasone furoate and related compounds including its metabolites for the glucocorticoid receptor of rat skin tissue.

The binding affinities of mometasone furoate (MF), its metabolites and related compounds for the glucocorticoid receptor of rat epidermis and dermis were measured. MF and its main metabolite exhibited binding affinities higher than those of alclomethasone dipropionate (ADP) and betamethasone dipropionate (BDP), but equivalent to betamethasone 17-valerate (BMV). For compound I (metabolite of MF), ADP, BDP and BMV, the binding affinity was found to be higher in epidermis relative to dermis. This difference in the dermal/epidermal binding ratio may be a favorable sign leading to a possible reduction of dermal collagen atrophy, a known side effect of glucocorticoids. In structure-binding relationship studies, esterification of the 17-OH by furoylation and introduction of the 9 alpha-Cl caused a marked increase of the binding affinity, whereas the 6 beta-hydroxylation led to a pronounced decrease.

Administration, Topical↗