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Biomedical subjects

S Ando

Publications and source records attributed to S Ando.

At least 325 records · Page 18Linked to original sources
PubMed1989

High resolution proton NMR studies of gangliosides. Structure of two types of GD3 lactones and their reactivity with monoclonal antibody R24.

Ganglioside GD3 was converted at room temperature to two stable lactones, denoted as GD3 lactones I and II. The reaction sequence was presumed to be GD3----GD3 lactone I----GD3 lactone II based on the time course of their production. Lactone I behaved as a monosialoganglioside and lactone II as a neutral species. The two lactones were isolated by DEAE-Sephadex column chromatography. The positions of the inner ester linkages were investigated by two-dimensional J-correlated proton NMR spectroscopy. An ester linkage was most likely formed between the carboxyl group of the external sialic acid residue and C9-OH of the internal sialic acid residue in lactone I. In addition to this ester linkage, a second ester linkage between the carboxyl group of the internal sialic acid and C2-OH of the galactose residue was likely formed in lactone II. The structural changes induced by lactonization were further examined by their reactivity with the monoclonal antibody R24 (Puckel, C. S., Lloyd, K. O., Travassos, L. R., Dippold, W. G., Oettgen, H. F., and Old, L. J. (1982) J. Exp. Med. 155, 1133-1147), which reacted with GD3. R24 was found to bind weakly to GD3 lactone I, but not to GD3 lactone II. The results suggest that the monoclonal antibody requires both sialic acid residues for high affinity binding, and the complete lactonization results in a loss of negative charges and/or a change in the overall conformation of the oligosaccharide moiety which may account for the loss of binding.

Animals↗
PubMed1989

Phospholipid-derived choline intermediates and acetylcholine synthesis in mouse brain synaptosomes.

Endogenous free choline levels and acetylcholine (ACh) synthesis in nerve terminals were investigated using cerebral cortical synaptosomes of C57BL/6 mice. Endogenous choline was produced at a rate ten-fold faster than ACh to provide levels adequate for the formation of the latter. The combined pool size of the water-soluble intermediates derived from phosphatidylcholine (PhC), such as glycerophosphorylcholine (GpCh) and phosphorylcholine (PCh), increased significantly during the first 10-15 min of incubation and was always higher than that of free choline. These results most likely indicate an effective degradation of PhC by the combined action of phospholipase A2/lysophospholipase, as well as by phospholipase C in synaptosomes. ACh synthesis proceeded at a constant rate in the presence or absence of exogenous free choline (0-10 microM) and was almost entirely abolished in the presence of 10(-6) M hemicholinium-3. These results suggest that ACh is effectively synthesized by free choline generated in synaptosomes by a coupling mechanism involving the high-affinity choline uptake system. No changes in the production rates of choline and ACh were observed between adult and aged mice.

Acetylcholine↗
PubMed1989

Biological and immunological properties of Sugi basic protein-pullulan conjugate. I. Suppressive effect on IgE antibody production and on IgE-mediated reactions.

Sugi basic protein (SBP), a major allergen of Japanese cedar pollen, conjugated to pullulan acquires suppressive activities for IgE, but not for IgG antibody production, and for IgE-mediated PK reactions in a SBP-specific manner. When either normal or IgE anti-SBP antibody-producing mice were treated with the conjugate, IgE anti-SBP antibody levels scarcely increased even after immunization with SBP + alum. This suppression was shown to be SBP specific and IgE selective. The ability of SBP-pullulan conjugate to elicit PK reactions on passively sensitized rat skin was markedly reduced. Furthermore, the conjugate inhibited the reactions mediated by the IgE antibodies and native SBP when it was injected into the IgE antibody-sensitized sites 2 h prior to SBP challenge. The reduced ability of the conjugate to elicit PK reactions was not due to loss of antigenic determinants during the conjugation procedures because binding activity of the conjugate to anti-SBP antibodies was as strong as that of native SBP. These results indicate that SBP-pullulan conjugate may be useful for 'desensitization therapy' against the pollinosis.

Allergens↗
PubMed1989

Central nervous system mechanisms involved in inhibition of renal sympathetic nerve activity induced by arginine vasopressin.

Previous studies have suggested that intravenous infusion of arginine vasopressin (AVP) inhibits sympathetic nerve activity (SNA) in rabbits by its action at the brainstem. This study aimed to determine, first, whether this action of AVP depended on functioning baroreflex mechanisms. The second aim was to determine the role of the nucleus tractus solitarii (NTS) in mediating this action of AVP. Experiments were performed in rabbits anesthetized with alpha-chloralose. Intravenous infusions of AVP (1, 3, and 10 mU/kg/min) resulted in progressive inhibition of renal SNA in rabbits with intact arterial baroreceptors and vagal afferents as well as in rabbits with sinoaortic denervation and bilateral vagotomy. The magnitudes of renal SNA inhibition evoked with AVP were comparable in the two groups. Renal SNA inhibition evoked with AVP at doses of 1 and 3 mU/kg/min in rabbits after sinoaortic denervation and vagotomy was totally blocked by chemical lesions with kainic acid of the bilateral NTS or the area postrema. Lesions of the NTS or the area postrema markedly attenuated (by about 60%) but did not totally block the response evoked with AVP at a dose of 10 mU/kg/min. AVP microinjected directly into the NTS did not evoke changes in renal SNA or arterial pressure, whereas AVP microinjected into the area postrema suppressed renal SNA. These results suggest that intravenous AVP at lower doses inhibited renal SNA by causing excitation of the NTS neurons, and this action of AVP did not depend on functioning baroreflex mechanisms. The second suggestion is that the NTS was unlikely to be the site where AVP directly interacted but instead received a neural connection, presumably from the area postrema, where AVP might directly interact.

Animals↗
PubMed1989

Biphasic forearm vascular responses to intraarterial arginine vasopressin.

Forearm vascular responses to arginine vasopressin (AVP) infused into a brachial artery in a wide range of infusion rates (0.05-2.0 ng/kg per min) were examined in 20 young healthy volunteers. Intraarterial AVP at lower doses (0.05 and 0.1 ng/kg per min) caused forearm vasoconstriction, whereas AVP at a dose of 0.2 ng/kg per min or higher caused forearm vasodilatation. The maximal forearm vasoconstriction was induced at the venous plasma AVP level of 76.3 +/- 8.8 pg/ml. Forearm vasodilatation was associated with the venous plasma AVP level of 369 +/- 43 pg/ml or higher. Forearm vasodilatation was the result of the direct effect of AVP since forearm blood flow and vascular resistance in the contralateral arm did not change. We attempted to explore the mechanisms involved in AVP-induced direct vasodilatation. The treatment with indomethacin, 75 mg/d for 3 d, did not alter AVP-induced forearm vasodilatation. In contrast, intraarterial infusion of isoosmolar CaCl2 totally prevented AVP-induced forearm vasodilatation. Intra-arterial CaCl2 also markedly attenuated forearm vasodilatation induced by intraarterial sodium nitroprusside, but did not alter forearm vasodilatation induced by intraarterial isoproterenol. These results indicate that the direct vascular effects of intra-arterial AVP on the forearm vessels are biphasic, causing vasoconstriction at lower doses and vasodilatation at higher doses. The direct vasodilatation induced by intraarterial AVP at higher doses is not mediated by prostaglandins but may involve cGMP-related mechanisms.

Adult↗
PubMed1989

[Studies on the flow properties of autopolymerizing hard-setting resins used as direct relining materials for denture bases].

Autopolymerizing hard-setting direct relining resin is currently being used in dentistry to attain denture bases that conform to the supporting tissues with a high degree of accuracy. The purpose of this study is to investigate the flow of six commercial hard-setting direct relining resins (Denture Liner, Kooliner, New Truliner, Rebaron, Swift, Tokuso Rebase) and several types of impression materials (zinc oxide-eugenol, polysulfide rubber, silicone rubber) using the parallel plate viscometer. The viscometer is used to measure the spread radius of samples (a volume of 0.5 cm3) between two parallel flat plates when a load of 750-gram weight is applied at 1, 10, 60, 100 seconds after loading has begun. In this experiment, the load was applied at 120, 150, 180, 210, 240, 300 seconds after mixing had begun. All the samples were mixed according to the manufacturer's recommendations. The findings were as follows; 1. The flow of the six commercial hard-setting direct relining resins could be compared with one another by the spread radius at 1 second after loading (r1) with no relation to time lapse after initiation of the mix. 2. Denture Liner, Kooliner, Rebaron and Swift had the same flow characteristic when r1 was the same. 3. Polysulfide rubber impression materials had similar flow characteristic to hard-setting direct relining resins.

Acrylic Resins↗
PubMed1989

[Urinary N-acetyl-beta-D-glucosaminidase activity in acute pyelonephritis patients with spinal cord injuries].

The urinary N-acetyl-beta-D-glucosaminidase (NAG) activities were determined in acute pyelonephritis patients with spinal cord injuries. The urinary NAG activity was significantly elevated in 23 of 31 cases (74%) compared with normal controls. Out of 7 acute pyelonephritis patients without spinal cord injuries, 4 patients (57%) showed significantly elevated urinary NAG activities. The urinary NAG activities were within normal range in 20 patients with acute simple cystitis and 11 patients with chronic complicated cystitis. Out of 6 patients with urethritis, only one case (17%) showed a significantly higher level of urinary NAG activity. Significantly higher levels in urinary NAG activities were observed in 6 of 9 patients (67%) with acute prostatitis and 5 of 9 patients (56%) with acute epididymitis. In patients with spinal cord injuries, having frequent urinary tract infections and complicated pathophysiological conditions, urinary NAG is one of the helpful laboratory findings for the diagnosis of acute pyelonephritis.

Acetylglucosaminidase↗
PubMed1989

[Development of a light curing denture base resin].

We developed the light cured direct relining material and used it clinically. In this study, a partial change in its components was made to improve both its strength and manipulability with the aim of using it as a denture base material. The physical properties of the new material, bonding to resin teeth, fit, as well as procedure were discussed. As for physical properties, the bending strength of the new material was increased by improving its organic filler, it becoming comparable to that of heat curing resin. The water absorption of the new material was the lowest of compared materials. The bonding strength of this material to resin teeth was increased by treatment with a light cured bonding agent and the fit of the new material to a test model was comparable to that of heat curing resin. Thus, the new material seems to be quite clinically effective as a denture base resin.

Composite Resins↗
PubMed1989

[Intended super-ovulation with HMG in the treatment of so-called functional sterility].

To investigate a new treatment for so-called functional sterility, 17 out of 456 infertile patients were treated in the past three years (age: 32.7 +/- 3.6 years old, infertile period: 5.9 +/- 1.4 years, M +/- S.D.). These patients were treated with HMG-HCG. The injection of HMG (75-450iu) was started on the 5th day of the menstrual cycle, and the follicular development was observed by ultrasonography. Then, HCG (10,000-20,000iu) was injected when 3 or 4 matured follicles (with a diameter greater than 20mm) were observed. In some cases, the endometrial biopsy was done in the mid-luteal phase and the effect of the treatment was examined morphologically. Pregnancies were observed in 6 cases (35.3%) and all of them were singletons. One of them spontaneously aborted at 9 weeks of gestation, but remaining five cases delivered at full term without any complications. The total dose of HMG was 2,116.8 +/- 843.3iu, and OHSS was observed in 5 cycles out of 31 cycles (16.1%). There was no other severe complication during the treatment. The growth of the endometrium thickened in the treated cases, but no time lag in endometrial dating could be found in the morphological study. These results indicated that the intended superovulation method for the treatment of so-called functional sterility was effective through the mechanism of the improvement of the implantation ratio.

Adult↗
PubMed1989

A novel sterol-regulated surface protein on chicken fibroblasts.

In the laying hen, two different receptors for apolipoprotein B (apoB)-containing lipoproteins are expressed on somatic cells and oocytes, respectively. The somatic protein has an apparent Mr of 130,000, while the oocyte receptor is a 95-kDa protein (1989. K. Hayashi, J. Nimpf, and W. J. Schneider, J. Biol. Chem. 264:3131-3139). In order to investigate the yet unresolved relationship between these two proteins, we applied immunoblotting with anti-receptor antibodies to extracts of oocytes and chicken embryo fibroblasts. IgG fractions that recognize the 95-kDa oocyte receptor did not cross-react with the somatic receptor; however, chicken fibroblasts as well as ovarian granulosa cells that had been exposed to sterols (cholesterol and 25-OH-cholesterol) or low density lipoprotein (LDL) were shown to express a novel immunoreactive protein with an apparent Mr of 110,000. This protein is localized on the cell surface, and is unable to bind apoB-containing lipoproteins. The formation of the 110-kDa protein in fibroblasts is induced in time- and concentration-dependent fashion by sterols, concomitant with a progressive decrease in the amount of functional 130-kDa receptor protein. Following its induction, exposure of cells to LDL, but not to high density lipoprotein, caused the disappearance of the immunoreactive protein. Furthermore, the production of the 110-kDa protein did not require protein synthesis. These data are compatible with the notion that this novel receptor-related, nonfunctional protein is a truncated intermediate in the degradation pathway for the 130-kDa apoB receptor, and that the truncation generates antigenic epitope(s) shared by the 95-kDa oocyte receptor and the 110-kDa protein, but not expressed on the somatic receptor.

Animals↗
PubMed1988

N-terminal amino acid sequence of a major allergen of Japanese cedar pollen (Cry j I).

A purified preparation of a major allergen of Japanese cedar pollen, sugi basic protein (SBP, Cry j I), was separated into 5 subfractions of 50-45 kDa. All of the SBP subfractions were confirmed to be reactive to IgE antibodies from patients with Japanese cedar pollinosis, and also to mouse anti-SBP monoclonal antibodies. The sequences of 20 N-terminal amino acids of these 5 subfractions were found to be identical. Peptide mapping analyses of the SBP subfractions showed similar patterns, with some differences which might in part be due to the existence of an N-linked carbohydrate chain. The N-terminal amino acid sequence of SBP was identical to the reported sequence of an allergen of mountain cedar which vegetated in North America.

Allergens↗
PubMed1988

Protease-nicked theta-toxin of Clostridium perfringens, a new membrane probe with no cytolytic effect, reveals two classes of cholesterol as toxin-binding sites on sheep erythrocytes.

A nicked theta-toxin (C theta), obtained by limited proteolysis with subtilisin Carlsberg, causes almost no hemolysis while it retains a nearly intact cholesterol binding site below 20 degrees C. Neither electron microscopic evidence for the formation of arc- and ring-shaped structures on the membrane nor toxin-stimulated influx of extracellular Ca2+ are detected in C theta-treated cells below 20 degrees C. Thus, event(s) in the lytic process are responsible for the temperature dependency of hemolysis, which is also supported by the observation that C theta requires higher Arrhenius activation energy for hemolysis than the native toxin. Using C theta as a probe due to its high affinity for membrane cholesterol without causing any obvious membrane changes, we demonstrated the possible existence of high- and low-affinity sites for theta-toxin on sheep erythrocytes. Both binding sites disappear by simultaneous treatment of the cells with sublytic doses of digitonin. Furthermore, C theta binds only to cholesterol among the chloroform/methanol-extractable, lipid components of sheep and human erythrocytes but not to the protein components derived from them. These results strongly suggest that cholesterol is an essential component of the both high- and low-affinity sites, and also imply that the modes of existence of cholesterol in the red cell membrane are heterogeneous.

Animals↗
PubMed1988

Improved method for large-scale purification of brain gangliosides by Q-sepharose column chromatography. Immunochemical detection of C-series polysialogangliosides in adult bovine brains.

A new chromatographic method for separation of bovine brain gangliosides has been developed using Q-Sepharose. Gangliosides were separated based not only on their sialic acid numbers but also on the sialic acid molecular species and chain lengths of the skeletal oligosaccharide portions. The following results indicate that this column chromatography has practical advantages in separating mixtures of gangliosides, especially positional isomers and molecular species with N-acetyl- or N-glycolylneuraminic acid. (1) the loading capacity of Q-Sepharose for gangliosides was very high; (2) most major gangliosides such as GM1, GD1a, GD1b, GT1b and GQ1b were isolated in a single step; (3) these major gangliosides were clearly separated from gangliosides containing, N-glycolylneuraminic acid when examined using Hanganutziu-Deicher antibody; (4) polysialogangliosides that have four or more sialic acid residues were isolated efficiently. It was shown by the combination of Q-Sepharose column chromatography with thin-layer chromatography/enzyme immunostaining that adult bovine brains possess C-series polysialogangliosides as minor components which are known as embryonic molecules in avian and mammalian brains.

Animals↗
PubMed1988

Effect of perfringolysin O on the lateral diffusion constant of membrane proteins of hepatocytes as revealed by fluorescence recovery after photobleaching.

Perfringolysin O is a thiol-activated cytolytic exotoxin the primary receptor of which is the membrane cholesterol on the cell surface. The effect of perfringolysin O was tested in various hepatocyte preparations. (i) Smears of fresh liver exposed to a mild H2O2 (1.0 mM) injury for 10 min at 37 degrees C, develop a 'peroxide-induced autofluorescence' (PIAF) on the membrane proteins. PIAF is suitable for measuring the average lateral diffusion constant (D) of the membrane proteins by means of fluorescence recovery after photobleaching technique (FRAP). Incubation for 5 min with 600 or 2000 units/ml of the perfringolysin O resulted in a significant increase (32 and 46%, respectively) of D as compared to the controls of the same age group (13-14 months). Various tests like heat denaturation of cholesterol saturation of perfringolysin O before its application as well as thiol-activation of the smears with dithiothreitol revealed that the increase of D is a specific toxin effect due mot probably to the reaction of perfringolysin O with cholesterol. (ii) Isolated hepatocytes were exposed to perfringolysin O and their viability as well as the release of two cytosolic enzymes (lactate dehydrogenase and glutamic-pyruvic transaminase) were measured; 40-60 units/ml of perfringolysin O in 30 min reduced the viability of the hepatocytes to zero and caused a release of about 70% of both cytosolic enzymes. The significance of the results is discussed from the points of view of both the toxin-effect and the FRAP method.

Animals↗
PubMed1988

Release of free fatty acids from rat cerebral synaptosomes under in vitro hypoxia.

Release of free fatty acids from rat cerebral synaptosomes, synaptic plasma membranes and mitochondria was studied under in vitro hypoxia. The release increased in the absence of oxygen. Removal of calcium ions from the medium suppressed the release. These trends were similar in every subcellular fraction tested. The data imply that the release of free fatty acids is caused by lack of oxygen but not lack of glucose, and that the presence of extracellular calcium is injurious to cells. An energy-independent mechanism for the release of free fatty acids is suggested.

Acetylcholinesterase↗
PubMed1988

Effect of neurophysin on enzymatic maturation of oxytocin from its precursor.

We examined the extent to which rates of enzymatic conversion of the oxytocin biosynthetic precursor to mature peptide are modulated by intramolecular and intermolecular assembly of precursor and polypeptide intermediates. The biosynthesized precursor contains hormone and neurophysin sequences linked by a Gly-Lys-Arg sequence and undergoes enzymatic processing reactions which include endoproteolytic cleavage at the Lys-Arg dibasic sequence, carboxypeptidase B-like exoproteolytic cleavage, and enzymatic amidation. We evaluated the effect of neurophysin on such processing reactions using semisynthetic precursors of oxytocin/bovine neurophysin I and synthetic oxytocinyl precursor intermediates as substrates. Neurophysin I at high concentration (0.7 mM) reduced the rates of carboxy-peptidase B-like conversion of oxytocinyl-Gly-Lys-Arg to oxytocinyl-Gly and the enzymatic amidation of oxytocinyl-Gly to mature (C-terminal amidated) oxytocin. The dependence of rate suppression on the concentrations of peptide substrate and neurophysin I suggested that suppression is due to intermolecular formation of hormone-neurophysin complexes which are aggregated at least to dimers. An analogous intramolecular neurophysin effect was found for endoproteolytic processing of semisynthetic precursors. Endoproteinase Lys-C cleaved the Lys11-Arg12 peptide bond in a native-like semisynthetic precursor at a significantly slower rate than it did an assembly-deficient precursor analogue. The difference in semisynthetic precursor endoproteolysis rates is most substantial at the high concentrations at which the native-like precursor would form dimers but the assembly-deficient analogue would not. The native-like semisynthetic precursor was more stable than the assembly-deficient precursor analogue to tryptic digestion. The concentration-dependent effects of neurophysin, both intramolecularly as a precursor domain and intermolecularly as an interacting protein, are likely to occur in the secretory granules in which the biosynthetic precursors are packaged. The molecular organization of both hormone/neurophysin precursors and the noncovalently complexed hormone-neurophysin intermediates can be expected to play a role in modulating enzymatic processing reactions that lead to mature neurohypophysial hormones.

Animals↗
PubMed1988

2,4-Dinitrophenylhydrazides of polysialogangliosides.

Treatment with 2,4-dinitrophenylhydrazine HCl in the presence of dicyclohexylcarbodiimide, converts gangliosides to their dinitrophenylhydrazides. This derivatization is the basis of a useful method for HPLC determination of gangliosides (K. Miyazaki, N. Okamura, Y. Kishimoto and Y. C. Lee (1986) Biochem. J. 235, 755-761). This procedure, however, yields two different GT1b products. By characterizing these two products using plasma desorption mass spectrometry, proton magnetic resonance and other chemical and physical techniques, we found that either one or two of the three sialic acid carboxyl groups in GT1b, were converted to dinitrophenylhydrazides. The remaining underivatized carboxyl groups formed lactones with hydroxyl groups from other carbohydrate residues. Also, while sialic acid residues of GD1a were fully derivatized, only one sialic acid in GD1b, two sialic acids in GT1a and two in GQ1b were converted to dinitrophenylhydrazides, the remaining carboxyl groups probably forming lactones. Sialic acid residues between galactose of the gangliotetraose chain and another sialic acid in polysialogangliosides appear to be underivatized possibly because of steric hindrance.

Chemical Phenomena↗