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S Hamano

Publications and source records attributed to S Hamano.

At least 163 records · Page 9Linked to original sources
PubMed1988

Study of the mechanism of inhibitory action of tranilast on chemical mediator release.

We investigated the mechanism of inhibitory action of tranilast on chemical mediator release by antigen-antibody reactions. Tranilast (10(-5)-10(-3) M) inhibited antigen (DNP-Ascaris)-induced histamine release from sensitized purified rat mast cells (PMC), but did not show an obvious influence on intracellular cyclic AMP. 45Ca uptake into PMC induced by antigen (300 micrograms/ml) was obviously suppressed by tranilast (10(-6)-10(-3) M). Tranilast (10(-4) M) inhibited antigen-induced histamine release from and 45Ca uptake into PMC independently of the presence or absence of glucose in the medium. On the other hand, 2-deoxyglucose (10(-2) M) markedly inhibited both responses in the absence but not in the presence of glucose. Tranilast slightly inhibited Ca-induced contraction of guinea pig taenia coli, but had no influence on aggregation of rabbit platelets. Verapamil (10(-6)-10(-4) M) had no effect on antigen-induced histamine release, but it markedly suppressed Ca-induced contraction and platelet aggregation. From these results, we suggest that the mechanism of inhibitory action of tranilast on the release of antigen-induced chemical mediator from mast cells involves the suppression of Ca uptake, but that its mode of action is apparently different from those of 2-deoxyglucose and verapamil.

Animals↗
PubMed1988

Mechanism of inhibitory action of tranilast on the release of slow reacting substance of anaphylaxis (SRS-A) in vitro: effect of tranilast on the release of arachidonic acid and its metabolites.

We investigated the mechanism of inhibitory action of tranilast, one of the anti-allergic drugs, on the release of slow reacting substance of anaphylaxis (SRS-A). Ionophore A23187 (0.5 or 0.2 micrograms/ml)-induced SRS-A release from rat peritoneal exudate cells (PEC) or human leucocytes was inhibited by tranilast (10(-5)-10(-3) M). The IC50 (the concentration which gives 50% inhibition) of tranilast on these reactions was approx. 10(-4) M. Prostaglandin (PG)E2 release from sensitized purified rat mast cells (PMC) by a specific antigen (DNP-Ascaris) was markedly suppressed by tranilast (10(-3) M). Similarly, ionophore A23187-induced PGE2 and 6-keto-PGF1 alpha releases from rat PEC were inhibited by tranilast (10(-5)-10(-3) M). DNP-Ascaris antigen-induced 3H-arachidonic acid (AA), 3H-PGE2, 3H-PGF2 alpha and 3H-PGD2 releases from rat PMC were markedly suppressed by tranilast (10(-5)-10(-3) M), DSCG (10(-5)-10(-4) M) and mepacrine (10(-3) M). The activity of AA-converting enzymes such as 5-lipoxygenase, cyclooxygenase, PGI2 synthetase, and glutathione-S-transferase was hardly influenced by tranilast (10(-5)-10(-3) M). From these results, we suggest that the mechanism of the inhibitory action of tranilast on the release of SRS-A is related to the processes prior to dissociation of AA from the membrane phospholipids.

Animals↗
PubMed1988

[Hydrocephalus and vasospasm after subarachnoid hemorrhage from ruptured intracranial aneurysms].

The relationship of the amount of subarachnoid blood to the incidence of acute hydrocephalus, delayed vasospasm, and chronic hydrocephalus was investigated in 47 patients with subarachnoid hemorrhage from ruptured intracranial aneurysms. Acute hydrocephalus, delayed vasospasm, and chronic hydrocephalus occurred in 29%, 7%, and 14% of Fisher Group 1 & 2 patients respectively, in contrast, 70%, 64%, and 58% of Fisher Group 3 patients (p less than 0.01). Thirty six percents of all patients had both acute hydrocephalus and vasospasm; Thirty two percents had neither. Twenty one percents had acute hydrocephalus, but no spasm; Eleven percents had spasm, but no acute hydrocephalus. Acute hydrocephalus and vasospasm were significantly associated (p less than 0.05). Most of patients with chronic hydrocephalus showed severe subarachnoid hemorrhage on initial CT scan, followed acute hydrocephalus, and highly associated with vasospasm. These sequelae of SAH are closely linked, mainly by the presence of subarachnoid clot, but there may be some direct causal relationship between them.

Acute Disease↗
PubMed1987

Role of thromboxane (Tx) A2 in guinea pig Forssman shock and the effect of OKY-046, Tx A2 synthetase inhibitor.

To study the role of thromboxane (Tx) A2 in Forssman systemic shock (FSS) in guinea pig, the effect of (E)-3-[p-(1H-Imidazol-1-ylmethyl)phenyl]-2-propenoic acid hydrochloride (OKY-046), a specific Tx A2 synthetase inhibitor, was studied. OKY-046 administered intravenously clearly prolonged survival time and protected against fatal shock. In shocked animals, definite decreases in serum complement hemolytic activity (CH50), leucocyte counts and platelet counts and an increase in lactate dehydrogenase (LDH) activity were observed. In addition, a significant increase of Tx B2 and incoagulability of blood were observed after shock. Whereas OKY-046 had no effect on the decreases in CH50, platelet counts and leucocyte counts, it inhibited the increase of Tx B2 and increased the amount of 6-keto PG F1 alpha. When Forssman antibody (half a lethal dose) was injected, a diphasic increase in airway resistance was observed. OKY-046 inhibited this diphasic increase in airway resistance. These data suggest a pathophysiological role for Tx A2 in FSS. OKY-046 inhibited the Forssman antibody induced respiratory disorders probably due to the inhibition of Tx A2 synthesis after shock.

Acrylates↗
PubMed1987

Effect of OKY-046, a new thromboxane A2 synthetase inhibitor, on experimental asthma in guinea pigs.

The effect of OKY-046, a newly synthetized thromboxane A2 (TxA2) synthetase inhibitor, on IgE mediated experimental asthma in guinea pigs was investigated. Indomethacin, a cyclooxygenase inhibitor, and tranilast (N-5'), a potent anti-allergic agent, were used as comparative drugs. OKY-046 clearly improved asthmatic respiratory disorders in guinea pigs. Whereas indomethacin had no effect on the changes of asthmatic respiration, tranilast significantly inhibited the changes. OKY-046 inhibited the in vitro antigen-induced contraction of sensitized guinea pig lung parenchyma. This antigen-induced contraction was also inhibited by tranilast, but not by indomethacin. OKY-046 inhibited the contractions of lung parenchyma caused by leukotriene C4, D4 and E4 (LTC4, LTD4 and LTE4), but not by histamine. Indomethacin showed a biphasic action on the contractile responses caused by histamine and LTD4 Consequently, contractions due to either agonist at low concentrations were inhibited by indomethacin, but those at high concentrations were enhanced. Tranilast inhibited the contraction of lung parenchyma induced by a low concentration of LTD4 but not that produced by histamine. Moreover, OKY-046 inhibited an elevation of concentration of thromboxane B2 (TxB2) in guinea pig lung perfusate after infusion of LTC4 but did not affect the elevation of 6-keto-PGF1 alpha. OKY-046 had no effect on the antigen-induced release of histamine but it inhibited the release of the slow reacting substance of anaphylaxis (SRS-A) from sensitized chopped lung tissues. Indomethacin at a high concentration inhibited the release of histamine but did not affect the release of SRS-A. Tranilast clearly inhibited the release of both mediators. These results suggest that OKY-046 inhibits IgE mediated experimental asthma in guinea pigs and that its main mechanism is related to the inhibition of LT induced contraction of airway smooth muscle and the release of SRS-A from lung tissues.

Acrylates↗
PubMed1987

A case of interstitial 1q deletion [46,XY,del(q25q32.1)].

A 10-year-old male with interstitial deletion of chromosome 1[46,XY,del(1)(q25q32.1)] is reported. Clinical features of the patient included dwarfism, severe mental retardation, microcephaly, flat nasal bridge, low-set ears, short neck, brachydactyly, clinodactyly of the 5th fingers and bilateral cryptorchidism. Comparison of phenotypic characteristics of the present case with those of six cases previously described with similar deletions of chromosome 1 permits the delineation of an identifiable syndrome.

Abnormalities, Multiple↗
PubMed1987

[Clinical effects of lipo-prostaglandin E1 in patients with delayed cerebral vasospasm].

Prostaglandin (PG) E1 is a potent vasodilator on the peripheral vessels and also has an inhibitory action of platelet aggregation. Thus it is expected that PGE1 may be used for the treatment of cerebral vasospasm in aneurysmal subarachnoid hemorrhage. Lipo-PGE1, the lipid emulsified PGE1, is not destroyed in the lung, has much longer half life in the circulation than PGE1 which is rapidly inactivated in the lung. The effects of intravenous injection of lipo-PGE1 on the cerebral hemodynamics and the central conduction time (CCT) of the sensory evoked potential under vasospastic conditions has been studied in eight patients. All these 8 patients demonstrated severe angiographic vasospasm and signs of cerebral ischemia. The 15-20 micrograms of lipo-PGE1 was administered every eight hours for 5 to 7 days. Within 6 hours of the first lipo-PGE1 treatment, the regional cerebral blood flow (rCBF) and the CCT measurements were reported to document the effect of treatment. The average pretreatment of rCBF on the right anterior, middle and posterior cerebral artery were 46.6 +/- 6.8, 56.4 +/- 7.3 and 58.8 +/- 8.9 ml/100 g/min and on the left side were 52.1 +/- 9.2, 49.1 +/- 10.8 and 56.1 +/- 9.2 ml/100 g/min respectively. With treatment these flows increased to 53.0 +/- 6.9, 64.3 +/- 5.3 and 63.0 +/- 4.6 ml/100 g/min respectively on the right side and 60.8 +/- 9.4, 60.6 +/- 9.7 and 60.6 +/- 7.2 ml/100 g/min respectively on the left. The CCT also demonstrated the improvement from 6.36 msec to 6.21 msec by the initial PGE1 treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Modulation by basic polypeptides of ATP-induced activation of tyrosine hydroxylase prepared from bovine adrenal medulla.

The effects of basic polypeptides on the activation of adrenal tyrosine hydroxylase by ATP were investigated to show a possible involvement of macromolecular cell components in the regulation of the enzyme activity. Basic polypeptides caused an enhancement of the activation of tyrosine hydroxylase by low concentrations of ATP, and the potentiating effects of these polypeptides were observed to be dependent on their concentrations. Kinetic studies showed that basic polypeptides caused an increase in the Vmax of the ATP-activated enzyme for the cofactor without any change in the Km. These results suggest that basic polypeptides convert the enzyme from a nonsusceptible form to a form susceptible to ATP, thus resulting in the potentiation of the ATP-induced activation. Furthermore, the activation by ATP of tyrosine hydroxylase was not observed after treatment of the enzyme preparation with CM-cellulose, and the responsiveness of the enzyme treated with CM-cellulose to ATP was partially restored by addition of basic polypeptides. These observations suggest the possibility that macromolecular cell components, presumably basic proteins, may be involved in the regulation of the activity of tyrosine hydroxylase through their modulating effects on the sensitivity of the enzyme to ATP within the cell.

Adenosine Triphosphate↗
PubMed1986

Inhibitory action of hydralazine on catecholamine secretion from cultured bovine adrenal chromaffin cells.

Hydralazine caused a concentration-dependent inhibition of the secretion of catecholamines induced by carbamylcholine or high K+ from cultured bovine adrenal chromaffin cells, and also caused the significant inhibition of radioactive calcium uptake induced by carbamylcholine into the cells. However, hydralazine failed to inhibit the secretion of catecholamines evoked by the calcium-ionophore, A23187. The inhibitory action of hydralazine on catecholamine secretion induced by carbamylcholine was not affected by increasing the concentration of calcium ion in the reaction mixture. These observations therefore seem to indicate that the inhibitory action of hydralazine is not due to either the blocking of receptors for carbamylcholine or the disruption of the secretory machinery, and suggest that the drug may cause the inhibition of catecholamine secretion through its blocking action on calcium influx into the cells.

Adrenal Glands↗
PubMed1986

Beneficial effect of OKY-046, a selective thromboxane A2 synthetase inhibitor, on experimental cerebral vasospasm.

Effects of OKY-046, a selective inhibitor of thromboxane (TX)A2 synthetase and a platelet aggregation inhibitor, on in vitro and in vivo models of cerebral vasospasm were studied. The contraction of the isolated rabbit basilar artery by an exposure to 1.0 ml of whole rabbit blood plus 0.05 or 0.1 units/ml of thrombin was diminished by the treatment with 10(-4) M of OKY-046 and/or 10(-6) M of cinanserin. When the whole blood of rabbits treated intravenously with 1 mg/kg/min of OKY-046 was used, the contraction of the basilar artery was decreased to about half of the control contraction. Angiographically recognized cerebral vasospasm in vivo, by a transorbital injection of 5.0 to 7.0 ml of autologous arterial blood into the cisterna magna of dogs, was suppressed by 0.05 and 0.5 microgram of OKY-046. Moreover, the decrease in the regional cerebral blood flow in autologous blood infused-dogs was inhibited by 0.5 microgram of OKY-046. The increase in TXB2 in the cerebrospinal fluid of dogs was significantly inhibited, and the level of 6-keto-PGF1 alpha was slightly increased by the treatment of OKY-046. The ratio of 6-keto-PGF1 alpha/TXB2 was increased from 1.5 to 5.2 in OKY-046-treated dogs. No effect on the basal tone and response to vasoactive agonists such as norepinephrine, KCl and PGE1 was observed in the isolated spiral thoracic aorta of guinea pigs or rabbits. Taken together with our previous findings, we conclude that the inhibition of cerebral vasospasm in the in vitro and in vivo models by the treatment of OKY-046 might be due to an inhibition of platelet aggregation, an inhibition of TXA2 generation and an increase in the ratio of PGl2/TXA2.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Microbial kinetics of beta-lactam antibiotics against Escherichia coli.

Microbial kinetics of Escherichia coli NIHJ JC-2 and E. coli B/r were investigated in the presence of beta-lactam antibiotics. To maintain a constant drug concentration during the experiment, a novel technique, using a dialysis membrane tube containing the drug solution, was successfully employed. The drug-affected generation curves of E. coli exhibited common features. After the addition of drug, an apparent lag period was noted, followed by a first-order decrease of the sensitive organisms and, 6 h later, by a regrowth of resistant organisms, depending on the antibiotic concentration used. The relationship between the apparent generation rate constant, kapp, and the antibiotic concentration was found to be nonlinear. This phenomenon is consistent with a saturable receptor site model for the drug action. A good linear free energy relationship was observed between the microbial kinetic parameter, kmax, and the alkaline degradation rate constants, kOH, of the cephalosporins studied.

Anti-Bacterial Agents↗
PubMed1984

Kinetic analysis and characterization of the bacterial regrowth after treatment of Escherichia coli with beta-lactam antibiotics.

The generation curves of Escherichia coli B/r and E. coli NIHJ JC-2 in the presence of several beta-lactam antibiotics were studied from the kinetic point of view. Apparent first-order regrowth of resistant organisms was observed approximately 6 h after addition of these antibiotics. The time courses of apparent viable counts could be interpreted in terms of the sum of the viable counts of sensitive and resistant organisms. To clarify the nature of the regrowth, experiments involving a second addition of antibiotic, single colonization by subculture, and synchronous cell culture were carried out. Several possible explanations for the results are discussed, including beta-lactamase production, selection in terms of membrane permeability, and mutation to acquire drug resistance. A selection process or a modification of membrane permeability caused by contact with the drug seems to be the most probable reason for the regrowth of the organisms.

Ampicillin↗
PubMed1983

Effects of thromboxane synthetase inhibitors on aggregation of rabbit platelets.

Thromboxane (TX) synthetase activity was selectively inhibited by (E)-3-[4-(1-imidazolylmethyl)phenyl]-2-propenoic acid hydrochloride monohydrate (OKY-046) and sodium (E)-3-[4-(3-pyridylmethyl)phenyl]-2-methyl-propenoate (OKY-1581) (OKYs). Their IC50 for the rabbit platelet enzyme were found to be 11nM and 3nM respectively. Arachidonic acid (AA) or collagen induced platelet aggregation, and generated TXA 2 and prostaglandins (PGs) in rabbit platelets. OKYs inhibited platelet aggregation and TXA2 generation without affecting PGs generation, while aspirin inhibited platelet aggregation, and TXA2 and PGs generation. There was a parallel relation between the degree of inhibition of platelet aggregation and TXA2 generation by OKYs, but the inhibitory effects of aspirin on platelet aggregation was related to that on both TXA2 and PGs generation. However, OKYs and aspirin did not inhibit ADP-induced platelet aggregation which did not involve the generation of TXA2 and PGs. These results suggested that TXA2 generation is related to platelet aggregation induced by AA or collagen, and that the inhibitory effect of OKYs on platelet aggregation is due to the inhibition of TX synthetase.

Animals↗