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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 757 records · Page 42Linked to original sources
PubMed1983

The inhibitory action of FR 34235 (a new Ca2+ entry blocker) as compared to nimodipine and nifedipine on the contractile response to norepinephrine, potassium and 5-hydroxytryptamine in rabbit basilar artery.

In isolated basilar arteries, FR 34235 (FR), a new Ca2+ entry blocker, inhibited the contractile response to potassium, norepinephrine and 5-hydroxytryptamine (5-HT) in a dose-dependent manner. The potency of the inhibitory action of FR was in the following order: potassium greater than 5-HT greater than norepinephrine. Nifedipine had a similar inhibitory action on the responses. Nimodipine had no inhibitory effect on the response to norepinephrine but suppressed the responses to potassium and 5-HT.

Animals↗
PubMed1983

Hemoglobin Okayama [beta 2 (NA 2) His replaced by Gln]: a new 'silent' hemoglobin variant with substituted amino acid residue at the 2,3-diphosphoglycerate binding site.

A new 'silent' abnormal hemoglobin, Hb Okayama [beta 2 (NA 2) His replaced by Gln], happened to be discovered in a diabetic Japanese female living in Okayama Prefecture, Japan, in the course of glyco-Hb measurement of the blood samples of diabetic patients. This variant did not differ from Hb A by conventional electrophoretic tests. Only the isoelectric focusing on PAG plate for the determination of glyco-Hb and the cation exchanger chromatography were successful in the separation of this abnormal variant from Hb A and glyco-Hb. Functional study of the whole blood demonstrated a slight increase of oxygen affinity.

2,3-Diphosphoglycerate↗
PubMed1983

Hemoglobin Kariya [alpha 40 (C5) Lys leads to Glu]: a new hemoglobin variant with an increased oxygen affinity.

A new abnormal hemoglobin, Hb Kariya [alpha 40 (C5) Lys leads to Glu], with an amino acid substitution at the alpha 1 beta 2 contact was discovered in a young Japanese man. This variant migrated to the anode faster than Hb A, being nearly the same as Hb I in electrophoretic mobility. It amounted to about 6% of the total hemoglobin of the hemolysate. This hemoglobin showed an increased oxygen affinity, decreased heme-heme interaction and a lowered 2,3-DPG effect.

Adult↗
PubMed1983

Cardiac inhibitory action of constituents of the marine green alga Ulva pertusa.

As part of a search for substances from marine organisms, which exhibit inotropic effects, the chemical constituents of the marine green alga, Ulva pertusa were investigated. The fractionated extract was tested for inotropic effects on the isolated guinea pig atria. The aqueous layer obtained from the acetone extract of fresh algae was concentrated, and the residue was extracted with methanol. The methanolic extract was fractionated by chromatography using mixtures of aqueous methanol. Elution with 50% aqueous methanol afforded material that had a significant negative inotropic effect. Further purification of this material by high-performance liquid chromatography (HPLC) using methanol-water (2:5) afforded crystalline adenosine, which was shown to be the active substance of U. pertusa, causing a negative inotropic action.

Adenosine↗
PubMed1983

Effects of restricted feeding on single neuron activity of suprachiasmatic neurons in rat hypothalamic slice preparation.

Influence of restricted feeding on single neuron activity in the rat suprachiasmatic nucleus (SCN) was examined using hypothalamic slice preparations. Feeding restriction for one month did not change SCN neuron activity in either normal light-dark schedule (LD) or constant light schedule (LL). Locomotor activity in vivo was increased for a few hours before and during feeding time by food restriction of both LD and LL rats. The present experiment suggested that the memory of feeding time produced by food restriction is independent of SCN neuron activity.

Animals↗
PubMed1983

Effects of adrenergic blockers on the inhibition of muricide by desipramine and noradrenaline injected into the amygdala in olfactory bulbectomized rats.

Muricide in olfactory bulbectomized rats (OB rats) is readily inhibited by systemic administration of desipramine (DMI) or microinjection of DMI and noradrenaline (NA) into the medial amygdaloid nucleus. The present experiment investigated whether the muricide inhibition produced by these forms of drug treatment was mediated by alpha- or beta-noradrenergic receptors in the central nervous system. Muricide inhibition produced by systemic administration of DMI was antagonized by an alpha-blocker phenoxybenzamine but unaffected by a beta-blocker sotalol, although administration of these adrenergic blockers alone had no effect on muricide. Muricide inhibition induced by the microinjection of DMI and NA into the medial amygdaloid nucleus was similarly antagonized by pretreatment of phenoxybenzamine injected into the same site, but sotalol had no effect. Injection of phenoxybenzamine or sotalol alone into the medial amygdaloid nucleus did not elicit any changes in muricide. These findings suggest that mechanisms mediated by brain noradrenergic alpha-receptor play an important role in muricide inhibition by tricyclic antidepressants in rats and that the medial amygdaloid nucleus is an important site of action of these drugs.

Adrenergic alpha-Antagonists↗
PubMed1983

Effect of prolonged cold storage on the mechanical activity of rabbit atria.

Even after 21 days of cold storage at 2 degrees C, rabbit atria still showed a detectable response only to isoproterenol while other cardiostimulants (norepinephrine, ouabain, anthopleurin-A and nicotine) failed to activate tissues stored up to 14 days. The specific fluorescence of catecholamines disappeared from the tissue after 5 days of cold storage. The maximum decrease in oxygen consumption and tissue catecholamine content was observed after 14 days and a concomitant decrease in tissue ATP content, Na+-K+, Ca2+ and Mg2+-ATPases was nearly maximal after 7 days of cold storage. The cold storage had no apparent effect on the ultrastructures of myocardial cells except a disappearance in glycogen granules.

Adenosine Triphosphate↗
PubMed1983

The effect of creatine on the developed tension and metabolic kinetics of isolated rabbit atria after prolonged cold storage.

During 14 days of cold storage the mechanical and metabolic functions and sarcolemmal enzyme activities were markedly decreased. Creatine significantly suppressed such decrease in oxygen consumption and preserved the ability to reproduce high energy phosphates from low temperature, resulted in recovery of mechanical activity by rewarming. However, cation transport enzymes, Na+, K+- and Ca2+-ATPase, were not affected, These results suggest the protective action of creatine on mammalian myocardium under cold storage.

Adenosine Triphosphatases↗
PubMed1983

Purification and Characterization of Griffonia simplicifolia Leaf Lectins.

Leaves from mature Griffonia simplicifolia plants were examined for the presence of leaf lectins possessing sugar binding specificities similar to the four known seed lectins (GS-I, GS-II, GS-III, GS-IV). Three (GS-I, -II, -IV) of the four known G. simplicifolia seed lectins were present in the leaves. Leaf G. simplicifolia lectins I and IV were similar to the respective seed lectins. Leaf GS-II, however, was composed of two types of subunits (M(r) = 33,000 and 19,000), whereas the seed lectin consists of only one type of subunit (M(r) 32,500). Seed and leaf GS-II lectins also had different isoelectric points. All leaf and seed lectins were similar with respect to their hemagglutination and glycoconjugate precipitation properties and all subunits contained covalently bound carbohydrate. Leaf GS-IV appeared slightly under-glycosylated compared to seed GS-IV.The fate of GS-I and GS-II seed lectins in aging cotyledons was investigated. GS-I isolectins usually contain isolectin subtypes associated with each main isolectin. Upon inbibition and germination, these GS-I isolectin subtypes disappeared. Over time, GS-II lectin did not change its disc gel electrophoretic properties.

Journal Article↗
PubMed1983

Conformational study of the salivary proline-rich polypeptides.

The conformational study of three proline-rich polypeptides of human whole saliva, with known primary structures, was performed by CD and 1H-n.m.r. spectra measurements. All these polypeptides contained more than four consecutive prolyl residues in their amino acid sequences. The occurrence of the poly-L-proline form II conformation in their structures was demonstrated with two of these polypeptides. The continuous prolyl residues in the third was suggested to take the same structure as the others.

Circular Dichroism↗
PubMed1983

Evaluation and management in consultation-liaison psychiatry.

The subjects were 95 medical and surgical inpatients referred to Kyushu University Hospital Psychiatric Consultation Service. The authors studied the mental status of each referred patient and elicited some Unclassified mental status cases. It was recommended, therefore, to bring in new concepts of normal condition and polymorphous condition in dealing with those Unclassified mental status cases which are often recognized as problematic both by the patient's primary physician and the psychiatric consultant. The ordinary style Single contact consultation was also compared with the Active follow-up consultation regarding the function of psychiatric consultations. The authors confirmed that most referring physicians who were supported by the Active follow-up consultation appreciated highly the evaluating function of a psychiatric consultant.

Adolescent↗
PubMed1983

Effects of amrinone on the transmembrane action potential of rabbit sinus node pacemaker cells.

Effects of amrinone on the membrane action potential and spontaneous activity were investigated in sinus node pacemaker cells of rabbit heart by use of microelectrode techniques. Amrinone (1 X 10(-4) M to 6 X 10(-6) M) caused a shortening of cycle length of spontaneous firing (SPCL) accompanied by an increase in the maximum upstroke velocity at phase O (Vmax) and amplitude of action potential (AAP), while it did not affect the maximum diastolic potential (MDP). All the effects of amrinone on sinus node pacemaker cells were markedly attenuated or abolished in a low calcium medium (Ca+ 0.1 mM or 0.3 mM) or in the presence of the slow channel blocking agent, verapamil (5 X 10(-7) M, 2 X 10(-6) M). The effects of amrinone were not antagonized by the beta-adrenoceptor blocking agent, pindolol (2 X 10(-7) M). These results indicate that amrinone has an intrinsic effect on sinus node pacemaker cells, increasing their spontaneous firing activity. It is also assumed that the effects of amrinone on sinus node cells are probably mediated by an augmentation of the slow calcium and/or sodium inward current through the cell membrane.

Action Potentials↗
PubMed1983

The presence of fucosyltransferases with different substrate specificity in human parotid saliva.

Using glycoproteins and milk oligosaccharides as substrate acceptors, we demonstrated at least two fucosyltransferases in human parotid saliva. One enzyme transferred L-fucose from GDP-fucose to the C-3 position of N-acetylglucosamine or glucose residue of oligosaccharide chains, and the other transferred to the C-4 position of N-acetylglucosamine residue of oligosaccharide chains.

Fucose↗
PubMed1983

Effect of amino acids and monoamines on the neuronal activity of suprachiasmatic nucleus in hypothalamic slice preparations.

Influences of amino acids and monoamines on the single unit discharges of the suprachiasmatic nucleus (SCN) were investigated using hypothalamic slice preparations. Iontophoretic application of GABA inhibited 90% and taurine inhibited 40% of SCN neurons, while glycine inhibited only 4%. L-glutamate excited about 50% of the neurons. Serotonin, noradrenaline and dopamine inhibited 30, 22 and 26% of the SCN neurons, respectively. Amino acid effects were observed equally in both the ventrolateral part of the SCN and the remaining part of it, while monoamine effects were observed preferentially in the ventrolateral part of the SCN where the optic fibers and serotonin nerves terminated. These results suggest that amino acids and monoamines modulate the neuronal activity of the SCN through their direct effects.

Amino Acids↗
PubMed1983

Purification and characterization of galactosephilic component present on the cell surfaces of Streptococcus sanguis ATCC 10557.

Previous studies have indicated that a galactosephilic component present on the bacterial cell surfaces of Streptococcus sanguis ATCC 10557 may be responsible for the salivary glycoprotein-mediated binding of the cells. The purpose of this study was to investigate the purification and characterization of galactosephilic cell surface component from S. sanguis ATCC 10557. A galactosephilic component involving fibrils on the cell surfaces was isolated by the techniques of freezing and thawing, and purified by an affinity chromatography on beta-D-galactose binding-Bio-Gel P-2 followed by gel filtrations on Bio-Gel P-150 and on Bio-Gel P-30. Both disk gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the purified product was homogeneous. The isoelectric point of the purified sample was 8.5 to 9.0. Treatment of the purified sample with pronase E reduced remarkably either the hemagglutinating activity or the precipitation reaction with proline-rich glycoprotein in human parotid saliva, suggesting that the active site may be present on the peptide moieties. When sugar specificity was examined by hemagglutination-inhibition test, D-galactose was the strongest inhibitor. The results of this study suggest that the galactosephilic component may be a bacterial lectin.

Cell Wall↗