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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 865 records · Page 48Linked to original sources
PubMed1980

Purification and characterization of Tora-bean (Phaseolus vulgaris) lectin.

A lectin purified from the Tora-bean (Phaseolus vulgaris) by affinity chromatography with Con-A Sepharose was shown to be a glycoprotein containing 7.8% neutral sugars (D-mannose, N-acetyl-D-glucosamine, L-fucose, and D-xylose, in a molar ratio of 9.6 : 2.0 : 0.6 : 0.7). Its molecular weight was 130,000, as estimated by exclusion gel chromatography, and SDS gel electrophoresis showed that it consists of four subunits of molecular weight 32,000. The lectin reacts with various glycoproteins, i.e., blood group substances, human parotid salivary glycoprotein, fetuin, and bovine submaxillary mucin. Divalent cations, such as Ca2+, Mn2+, and Mg2+, appear to stimulate its reactivity. Inhibition tests using the glycopeptide fragment from fetuin and some oligosaccharides, as well as the binding test with 14C-N-acetyl-lactosamine suggest that the sequence of D-galactose, N-acetyl-D-glucosamine, and D-mannose residues in the carbohydrate chain of fetuin is essential for binding.

Acetylglucosamine↗
PubMed1980

Vasorelaxant action of caroverine fumarate (a quinoxaline derivative), a calcium-blocking agent.

1 Caroverine fumarate, 1-(2-diethylaminoethyl)-3-(p-methoxy-benzyl)-1,2-dihydro-2-quinoxalinone fumarate, caused a greater inhibition of the pressor response to KCl (8 x 10(-2) M) than that to noradrenaline (10(-6) M) in the rat hindquarter preparation. 2 In the isolated aorta of the rat, caroverine (up to 10(-6) M) markedly suppressed the contraction caused by KCl (4 x 10(-2) M) (high-K) but had little effect on the contractile response to noradrenaline (10(-6) M) whether added before the spasmogen or in its presence. 3 In the high-K-treated aorta, caroverine shifted the concentration-response curve for external calcium to the right, competitively. The negative logarithm of the affinity (pA2) of caroverine was calculated to be approx. 7. 4 Increased 45Ca uptake of the high-K-treated aorta measured by a modified lanthanum method was inhibited by either caroverine (3 x 10(-6) M) or verapamil (10(-6) M). 5 Concentrations of caroverine and verapamil reducing high-K-induced aortic contraction to 50% of its maximum were 2.4 x 10(-7) and 6.6 x 10(-8) M respectively. 6 Following washout the caroverine-induced inhibition of high-K-induced aortic contraction was more rapidly restored than the verapamil-induced inhibition. 7 These results suggest that caroverine fumarate is a specific and readily reversible calcium influx inhibitor in the rat vascular smooth muscle.

Animals↗
PubMed1980

The inhibitory action of two thrombin inhibitors (TI-189 and TI-233) on the contractile responses to 5-hydroxytryptamine and prostaglandin endoperoxide analogue (U-44069) in isolated vascular strips.

1. Two arginine derivatives that were developed as thrombin inhibitors (TI-189 and TI-233) selectively inhibited the 5-hydroxytryptamine (5-HT)-induced contraction of rabbit aortic strips in a competitive manner. The PA2 values of TI-189 and TI-233 were 5.24 +/- 0.21 and 6.23 +/- 0.32 respectively. 2. Even at 10(-4) M they had no inhibitory effect on the contractile response to noradrenaline (NA), histamine, prostaglandin E2 (PGE2), PGF2 alpha, arachidonic acid or potassium in rabbit aortic strips. 3. In dog basilar and coronary arterial strips and also in rat fundus, both agents inhibited the 5-HT response in a non-competitive manner. 4. At 10(-5) M, TI-233 but not TI-189 antagonized effects of NA and KCl in the dog basilar and coronary arteries. 5. These arginine derivatives decreased the contractile responses induced by a prostaglandin endoperoxide analogue (U-44069) in rabbit aorta and in dog basilar and coronary arteries but there was no evidence for competitive antagonism. 6. These results indicate that the arginine derivatives are competitive antagonists selective for 5-HT receptors in rabbit aorta.

Animals↗
PubMed1980

The potent depolarizing action of palytoxin isolated from Palythoa tubercurosa on the isolated spinal cord of the frog.

1. The effects of palytoxin (PTX) isolated from Palythoa tubercurosa were tested on the isolated intra-arterially perfused spinal cord of the frog. The resting and evoked potentials were recorded by means of a sucrose-gap technique. 2. PTX caused a marked depolarization of both ventral and dorsal roots. The minimum effective concentration was extremely low, approximately 10(-11) M. During the depolarization the evoked ventral and dorsal root potentials were markedly reduced in amplitude. The ventral root reflex was first augmented and then decreased. 3. The depolarization caused by PTX was markedly reduced when the preparation was perfused with NaCl-deficient medium. However, tetrodotoxin (10(-7) M) only slightly inhibited the depolarization. 4. In a high Ca2+ medium (3.6 mM), the time required to reach the maximum depolarization evoked by PTX was significantly prolonged. In contrast, in a low Ca2+ medium (0.9 mM), PTX caused a marked depolarization soon after application. In a Ca2+-free, Mg2+ (9.0 mM) medium, PTX caused rhythmic oscillatory potentials in both ventral and dorsal roots. 5. The potency of N-acetyl PTX was one hundredth that of the parent compound. 6. It is suggested that PTX may interfere with the stabilizing action of Ca2+ on the neuronal membrane, consequently facilitating Na+ permeability. The primary amine in the PTX molecule may be important for its pharmacological action.

Acrylamides↗
PubMed1980

Characteristics contractile response to the calcium ionophore, A23187, in guinea-pig vas deferens.

1. In the guinea-pig isolated vas deferens, the calcium ionophore, A23187, initially caused a phasic contraction followed by rhythmic activity. 2. Treatment with atropine, phentolamine, tetrodotoxin and reserpine modified neither of the components of the contraction induced by the ionophore. Verapamil and nifedipine abolished the rhythmic activity but had no effect on the phasic contraction. 4. In a calcium-free solution, both components of the contraction were abolished. 5. It is suggested that A23187 is able to cause contraction by a direct action on the smooth muscle of guinea-pig vas deferens.

Animals↗
PubMed1980

Reactivity of isolated canine cerebral arteries to adenine nucleotides and adenosine.

ATP (10(-8)-10(-5) M) produced phasic contraction in the canine basilar artery and relaxation in the middle cerebral artery. At high concentrations (10(-5) and 10(-4) M) a contractile response in the middle cerebral artery occasionally preceded relaxation. ADP, AMP, c-AMP and adenosine (10(-8)-10(-4) M) caused relaxation in all preparations except that ADP produced contraction in both cerebral arteries at high concentrations (10(-5) and 10(-4) M). These effects were observed in the absence or presence of active tension induced by 5-HT. The potency of ADP in producing vasodilation in the middle cerebral artery was greater than in the basilar artery, whereas that of the other agents was reversed. c-AMP showed the lowest potency among the agents tested on both arteries. The relaxing responses, but not contractile responses, to agents used were partially inhibited by theophylline. Phentolamine, propranolol, atropine, tetrodotoxin, ouabain or quinidine had little effect on both the contractile and relaxing responses. From these results, it is concluded that the canine cerebral arteries respond well to adenine nucleotides and adenosine and that the relaxing response is in part caused through theophylline-sensitive receptors.

Adenine Nucleotides↗
PubMed1980

The effect of age on the development of hyperemotionality following bilateral olfactory bulbectomy in rats.

The effect of age on the development of hyperemotionality including muricide induced by either olfactory bulbectomy or isolated housing was studied in rats. In olfactory bulbectomized groups, 13-week-old rats showed the highest score of emotionality and shortest latency in the onset of hyperemotionality and muricide among any other groups of rats. On the other hand, in the groups subjected to isolation, 4-week-old rats showed a higher score of emotionality than 13-week-old rats. These results suggest that the age of the rat at the beginning of experiment is quite important in the induction of hyperemotionality following both olfactory bulbectomy and isolated housing.

Aging↗
PubMed1980

Interaction of parotid saliva basic glycoprotein with Streptococcus sanguis ATCC 10557.

It is postulated that an initial step in dental plaque formation is the adherence of oral bacteria to the salivary pellicle. Recently, we have found that a proline-rich and basic glycoprotein (MGP) from human parotid saliva, which is successfully purified by Concanavalin A-Sepharose affinity chromatography, binds to some oral streptococci such as S. mitis and S. sanguis. This paper deals with some inhibitors which affect the binding of the MGP to S. sanguis ATCC 10557. The assay for the binding ability of the radioactive MGP to the bacterial cells was performed by incubation of the reaction mixture containing 10 microgram of [3H]MGP (6000 dpm) and about 4.5 mg of bacterial cells (dry weight) in 0.5 ml of 0.05 M Tris-HCl buffer containing 0.05 M NaCl, pH 8.0 with a final volume of 0.51 ml. After 1 hour standing at 4 degrees C, the cells were washed five times with the same buffer. The resulting sediment was solubilized in 0.5 ml of NCS tissue solubilizer and the radioactivity was measured. The binding of the radioactive MGP to bacterial cells was specifically inhibited by galactose, lactose and N-acetyllactosamine. Applications of heat and trypsin on the cell surface, strikingly reduced the binding ability. These findings strongly suggested that a lectin-like substance may be present on the bacterial cell surface.

Adult↗
PubMed1980

Further studies on the functional properties of hemoglobin M Hyde Park.

The oxygen binding properties of Hb M Hyde Park (92 beta, histidine leads to tyrosine) were reinvestigated directing special care to testing the wave length-dependence of the oxygen equilibrium curve and to stabilizing hemoglobin samples using a methemoglobin reductase system. There was no indication that the Hb M Hyde Park fraction separated on a DEAE Sephadex column contained an unknown hemoglobin derivative which appeared in earlier studies. Contrary to earlier observations, there was no significant wave length-dependence of the equilibrium curve of Hb M Hyde Park, verifying the spectrophotometric determination of oxygen saturation. The reductase system satisfactorily reduced the normal alpha chain met hemes without reducing the abnormal beta chain met hemes. The oxygen binding property of Hb M Hyde Park is characterized by 3 to 4 times higher oxygen affinity than that for normal hemoglobin, complete loss of cooperativity, and substantially preserved Bohr effect. These results are consistent in part but not entirely with those observed by earlier investigators. The oxygen affinity of Hb M Hyde Park is between the affinity of the oxy structure and the deoxy structure of normal hemoglobin. Oxygen equilibrium curve of red cell suspension and whole hemolysate containing Hb M Hyde Park were biphasic, indicating that Hb M Hyde Park also exhibited the high oxygen affinity in those samples.

Cytochrome-B(5) Reductase↗
PubMed1980

Hemoglobin takamatsu (beta 120 (GH 3) Lys leads to Gln): a new abnormal hemoglobin detected in three unrelated families in the takamatsu area of shikoku.

A survey of hemoglobinopathies which was carried out in the Takamatsu district during the period from January to August 1979 detected six families with abnormal hemoglobins. Approximately 6010 inhabitants were screened. Three of these families had the same new Hb variant (Hb Takamatsu beta 120 Lys leads to Gln) that has not been previously reported. Existence of a blood relationship among these three families could not be established even after careful family studies. This abnormal hemoglobin was not associated with adverse symptoms and gave normal hematologic findings in the carriers. The isopropranol test was negative, oxygen affinity was within the normal range, and biosynthetic ratio in reticulocytes was around 1.0. One of the difficulties in the structural analysis of this hemoglobin was related to complete superposition of abnormal beta XT-12b,13 on a beta T-8,9 peptide in the fingerprint of the trypsin digest of aminoethylated aberrant beta X chain. This was overcome by collection of abnormal tryptic beta core (beta XT-10-13) from unmodified beta X chain, and subsequent digestion by chymotrypsin. Edman analysis of the chymotryptic peptides thus obtained successfully confirmed the substitution to be beta 120 Lys leads to Gln.

Adult↗