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T Satoh

Publications and source records attributed to T Satoh.

At least 721 records · Page 40Linked to original sources
PubMed1993

Down-regulation of murine contact sensitivity by hapten-amino acid derivatives.

The low responsiveness of contact sensitivity (CS) in sensitized and challenged mice was induced by using hapten-amino acid derivatives. Subcutaneous injection of trinitrophenyl (TNP)-lysine or oxazolone-glycine inhibited ear swelling responses in mice that received rechallenge. The inhibitory effect was long-lasting and antigen-specific. TNP-lysine blocked the transfer of CS in vivo and the binding of immune lymph node cells to antigen in vitro. Thus, the suppression was mediated by inhibition of effector cells, but not associated with the generation of efferent limb-acting suppressor cells. The tool reported herein seems to be quite useful for controlling ongoing murine CS to simple chemicals.

Amino Acids↗
PubMed1993

Intracellular signaling in the regulation of renal Na-K-ATPase. II. Role of eicosanoids.

We recently reported a novel intracellular mechanism of renal Na-K-ATPase regulation by agents that increase cell cAMP, which involves protein kinase A-phospholipase A2 and is mediated by one or more arachidonic acid metabolites (Satoh, T., H. T. Cohen, and A. I. Katz. 1992. J. Clin. Invest. 89:1496). The present studies were, therefore, designed to assess the role of eicosanoids in the modulation of Na-K-ATPase activity in the rat cortical collecting duct. The effect of various cAMP agonists (dopamine, fenoldopam, vasopressin, forskolin, and dibutyryl cAMP), which inhibited the pump to a similar extent (approximately 50%), was independent of altered Na entry as it was elicited in the presence of amiloride or nystatin, or when NaCl was replaced with choline Cl. This effect was completely blocked by SKF 525A or ethoxyresorufin, two inhibitors of the cytochrome P450-dependent monooxygenase pathway, or by pretreating the animals with CoCl2, which depletes cytochrome P450. Equimolar concentrations (10(-7) M) of the cyclooxygenase inhibitors indomethacin or meclofenamate caused only a partial inhibition of the cAMP agonists' effect on the pump, whereas nordihydroguaiaretic acid or A 63162, two inhibitors of the lipoxygenase pathway, were without effect. Furthermore, two products of this pathway, leukotriene B4 and leukotriene D4, had no effect on Na-K-ATPase activity, and ICI 198615, a leukotriene receptor antagonist, did not alter pump inhibition by cAMP agonists. Several P450 monoxygenase arachidonic acid metabolites (5,6-epoxyeicosatrienoic acid; 11,12-epoxyeicosatrienoic acid; 11,12-dihydroxyeicosatrienoic acid; and 12(R)-hydroxyeicosatetraenoic acid) as well as PGE2 inhibited the Na:K pump in dose-dependent manner, but the effect of PGE2 was blocked when Na availability was altered, whereas that of 12(R)-HETE remained unchanged. We conclude that the cytochrome P450-monooxygenase pathway of the arachidonic acid cascade plays a major role in the modulation of Na:K pump activity by eicosanoids in the rat cortical collecting duct, and that products of the cyclooxygenase pathway may contribute to pump inhibition indirectly, by decreasing intracellular Na.

Animals↗
PubMed1993

Serum inorganic fluoride levels in mildly obese patients during and after sevoflurane anesthesia.

Serum inorganic fluoride levels in obese versus control patients were compared during and after sevoflurane anesthesia. Mean serum inorganic fluoride levels in the obese group increased more rapidly and were significantly higher than in the control group at each sampling time (P < 0.01). The area under the curve of fluoride concentration, versus time up to 24 h and 48 h in the obese patients, was significantly greater than that in the nonobese patients (P < 0.001). Peak serum fluoride level in the obese patients was 51.7 +/- 2.5 mumol/L and exceeded 50 mumol/L for nearly 2 h. Our study showed that serum fluoride concentrations between mildly obese and nonobese patients differed during and after sevoflurane anesthesia.

Adult↗
PubMed1993

Enzymatic properties of squalene epoxidase from Saccharomyces cerevisiae.

Squalene epoxidase is a microsomal membrane-associated enzyme that acts as an important regulator in the sterol biosynthetic pathway. In this study, the enzymatic properties of squalene epoxidase from Saccharomyces cerevisiae were examined. Unlike Candida squalene epoxidase, S. cerevisiae squalene epoxidase required NADPH for enzyme reaction. However, S. cerevisiae enzyme reaction did not require FAD or autologous S105 fraction. Unlike rat squalene epoxidase, the activity of S. cerevisiae was reduced by Triton X-100, a nonionic detergent. Terbinafine, an inhibitor of fungal squalene epoxidase, inhibited the enzyme in a non-competitive manner, while NB-598, an inhibitor of mammalian squalene epoxidase, barely inhibited it in a partially non-competitive manner. Thus, the properties of squalene epoxidase from S. cerevisiae were different from those of squalene epoxidase from rats and Candida, which were previously known. We propose that a species difference of squalene epoxidase exists not only between animals and fungi but between Candida and Saccharomyces.

Animals↗
PubMed1993

Inflammatory activity of polymeric photoproducts of chlorpromazine.

To confirm the inflammatory activity of polymeric photoproducts (CPZ-polymers) of chlorpromazine (CPZ), which were obtained by gel filtration of a UV-pre-irradiated CPZ aqueous solution, the histamine release from rat peritoneal exudate cells was studied and the paw-inflammation in mice induced by these CPZ-polymers was examined. CPZ-polymers induced a dose-dependent histamine release at concentrations of 1, 3 and 10 mg/ml. This effect was approximately one-tenth of that of compound 48/80. Furthermore, CPZ-polymers markedly induced lasting paw-edema in a dose-dependent manner, the swellings remaining for at least 96 h. When intraperitoneally injected into mice, CPZ-polymers induced a significant elevation of histamine release in the peritoneal cavity 0.5 h after the injection, compared with a control group. The histamine levels in the cavities returned to normal within the next 0.5 h, and remained normal for at least 23 h, indicating that histamine release may be caused only in the early stages of CPZ-polymer-induced inflammation. The inflammatory activity of the CPZ-polymers suggests that they are inflammatory substances formed from CPZ by UV-irradiation.

Animals↗
PubMed1993

Pharmacological and pharmaceutical properties of freeze-dried formulations of egg albumin, indomethacin, olive oil, or fatty acids.

Formulations consisting of egg albumin, indomethacin (IND), and olive oil or fatty acids, were prepared by vigorous stirring using a high-speed homogenizer and subsequent freeze-drying. To confirm the anti-inflammatory properties and ulcerogenic effects of the formulations, we examined the action of the formulations on carrageenan-induced edema in rats as well as their ulcerogenic actions in the same species. Compared with IND alone, albumin-IND-olive oil (9:1:4.3), albumin-IND-linolenic acid (9:1:4.3), albumin-IND-linolic acid (9:1:4.3), albumin-IND-oleic acid (9:1:4.3), albumin-IND-stearic acid (9:1:4.3), and albumin-IND-tristearin (9:1:4.3) formulations all exhibited a more potent inhibitory effect on carrageenan-induced edema. In addition, the inhibitory effects on edema formation of an albumin-IND (9:1) complex was as strong as that of IND alone. These results suggested that the bioavailability of IND was increased by olive oil, fatty acid, and tristearin as absorbefacient agents. The increase in the bioavailability was evident from the fact that the mean plasma levels, maximum plasma levels (Cmax), and area under plasma concentration-time curve (AUC) values after oral administration of the albumin-IND-olive oil (9:1:4.3) formulation was significantly greater than that after administration of the drug alone. With respect to their ulcerogenic properties, the formulations were significantly less active than IND alone, suggesting that a reduction in the ulcerogenic activity of IND was by produced complexation with egg albumin.

Administration, Oral↗
PubMed1993

Pharmacological and pharmaceutical properties of freeze-dried formulations of egg albumin, indomethacin, olive oil, or fatty acids. II.

To confirm the increased bioavailability of indomethacin (IND) when incorporated in a preparation with egg albumin and olive oil, we studied the detailed pharmaceutical characteristics of a ternary formulation consisting of egg albumin, IND and olive oil. From the results of X-ray powder diffraction measurements, the drug in the formulation was found to be in an amorphous form. When orally administered to rats, the ternary formulation significantly increased the plasma concentration and cumulative biliary and urinary excretion of IND alone as well as the urinary excretion of its major metabolite, desmethylindomethacin, compared with the drug alone. In addition, the dissolution rate of IND from the formulation was higher than that of the drug alone. These results clearly suggest that the bioavailability of IND was markedly improved by incorporating it in a protein-drug formulation containing olive oil as an absorbefacient element, and this effect may be due to an increased absorption of IND.

Administration, Oral↗
PubMed1993

Syntheses and inhibitory effects on gastric lesions of 4-guanidinomethylbenzoic acid arylamides.

A novel series of 4-guanidinomethylbenzoic acid (GMBA) arylamides was synthesized. Several showed more potent inhibitory effects on stress-induced gastric lesion in rats than cetraxate. We selected 4-guanidinomethylbenzoic acid (2'-ethoxycarbonyl)phenylamide 3 for further pharmacological assessments because it had low toxicity. Compound 3 showed significant inhibitory effects on stress-, HCl-ethanol- and indomethacin-induced gastric lesions and gastric secretion, the ED50 values being 34.4, 45.0 and 23.0 mg/kg (p.o.) and 240 mg/kg (i.d.), respectively. Furthermore, this compound restored the reduction of gastric mucus caused by the stress-loading and inhibited compound 48/80-induced ulcer.

Animals↗
PubMed1993

Syntheses and inhibitory effects on gastric lesions of trans-guanidinomethylcyclohexane carboxylic acid arylamides.

A novel series of trans-guanidinomethylcyclohexanecarboxylic acid (trans-GMCHA) arylamides was synthesized. The several trans-GMCHA arylamide derivatives showed more potent inhibitory effects on the stress- and HCl-ethanol-induced gastric ulcers than cetraxate in rats. In acute toxicity studies in mice, most amides showed such severe toxicity that all mice injected with these compounds (50 mg/kg, i.p.) died. However, mice injected with the trans-GMCHA (2'-,3'- and 4'-ethoxycarboxy)phenylamide (7, 8 and 9) which bear an alkyloxycarbonyl group at benzene ring survived. From these results, trans-GMCHA (2'-ethoxycarbonyl)phenylamide (7) was selected as a promising anti-ulcer agent.

Animals↗
PubMed1993

Comparison of the motor-stimulating action of EM523, an erythromycin derivative, and prostaglandin F2 alpha in conscious dogs.

The effect of EM523 [de(N-methyl)-N-ethyl-8,9-anhydroerythromycin A 6,9-hemiacetal], an erythromycin derivative, on gastrointestinal motility was investigated using conscious dogs in the fasting state, and it was compared with those of motilin and prostaglandin F2 alpha (PGF2 alpha). EM523 and motilin given as i.v. infusions induced strong contractions in the stomach that migrated along the intestine. On the other hand, PGF2 alpha stimulated intestinal contractions, but its effect on gastric motility was weak. EM523 had 1/50 the potency of motilin and 6 times the potency of PGF2 alpha for stimulation of intestinal motility. Atropine at 0.1 mg/kg, i.v. strongly inhibited gastrointestinal contractions induced by EM52 EM523 or motilin and partly inhibited PGF2 alpha-induced intestinal motility. ICS-205-930, a 5HT3-receptor antagonist, at a dose of 1 mg/kg, i.v. strongly inhibited EM523 or motilin-induced gastric contractions but did not affect the action of PGF2 alpha. Infusion of EM523 at 100 micrograms/kg/hr induced strong migrating contractions even when motility was depressed by dopamine infusion or laparotomy. Infusion of PGF2 alpha at 300 micrograms/kg/hr stimulated intestinal but not gastric motility under these conditions. The results of this study indicate that the cholinergic pathway and 5HT3 receptors are involved in EM523 and motilin-induced migrating gastrointestinal contractions, whereas the cholinergic pathway seems to be only partly involved in PGF2 alpha-induced intestinal contractions.

Animals↗
PubMed1993

The protective effect of 4-hydroxy-2-methyl-N-[2-(tetrazol-5-yl)- phenyl]-2H-1, 2-benzothiazine-3-carboxamide-1, 1-dioxide monosodium salt (HX-1920) on cisplatin-induced toxicity in rats.

The protective effect of 4-hydroxy-2-methyl-N-[2-(tetrazol-5-yl)-phenyl]-2H-1, 2-benzothiazine-3-carboxamide-1, 1-dioxide monosodium salt (HX-1920) on the nephrotoxicity of cisplatin was studied in rats. Effects of HX-1920 on antitumor activity and emesis induced by cisplatin were also examined using mice and ferrets, respectively. All 10 rats injected with both HX-1920 and LD50 of cisplatin survived for 14 days. After 24 hr, co-administration of HX-1920 significantly increased the urinary excretion of cisplatin in rats. HX-1920 also significantly inhibited the cisplatin-induced elevation of urinary N-acetyl-beta-D-glucosaminidase, blood urea nitrogen and plasma creatinine concentrations in rats. HX-1920 had no effect on the number of white blood cell. HX-1920 tended to reduce the emesis induced by cisplatin in ferrets. Furthermore, there was no difference in the survival curve between the cisplatin group and the HX-1920 plus cisplatin group in mice inoculated with P 388 leukemia cells. Thus, HX-1920 did not modify the antitumor activity of cisplatin. These results suggest that HX-1920 has a protective effect on the nephrotoxicity of cisplatin without inhibiting its antitumor activity.

Acetylglucosaminidase↗
PubMed1993

Alteration by prolonged oral administration of a thyrotropin-releasing hormone analog, TA-0910, of the pituitary-thyroid axis in subjects with brain stroke.

We evaluated whether prolonged oral administration of a novel analog of thyrotropin-releasing hormone (TRH), TA-0910, may change the pituitary-thyroid axis in human subjects with brain stroke. The subjects were given one oral dose of 2.5-20 mg of TA-0910 daily for 8 weeks, and then blood levels of TA-0910, thyroid hormones and thyrotropin (TSH) were measured. Plasma levels of TA-0910 were elevated with increasing doses. After administration of TA-0910, the basal levels of thyroid hormones and TSH had a tendency to increase and decrease, respectively, but those changes remained in the normal range. The secretion of TSH in response to TRH was not significantly affected by TA-0910 administration. No significant changes in other pituitary hormones were observed after TA-0910 administration. The present data indicate that prolonged oral administration of TA-0910 did not significantly alter the pituitary-thyroid axis in subjects with brain stroke.

Administration, Oral↗
PubMed1993

Differences in the induction of carboxylesterase isozymes in rat liver microsomes by perfluorinated fatty acids.

1. Differences in the ability of metabolically-inert peroxisome proliferators (perfluoro-n-decanoic acid (PFDA, C10), perfluoro-n-octanoic acid (PFOA, C8), perfluorooctane sulphonic acid (PFOS, C8) and 1-H,1-H-pentadecafluoro-n-octanol (PFOL, C8)) to induce three forms of hepatic microsomal carboxylesterase, namely RL1, RL2 and RH1, in the male rat were studied by measuring changes in hydrolytic activities towards p-nitrophenyl acetate (PNPA), isocarboxazid (ISOC) and butanilicaine (BUTA), which are thought to be specific substrates for RL1, RL2 and RH1, respectively, and by evaluating changes in the contents of the three isozymes by radial immunodiffusion assay with specific antibodies. 2. The administration of PFDA rather specifically decreases PNPA hydrolase activity and RL1 content. On the other hand, PFOA, PFOS and PFOL markedly increase all three hydrolase activities and the content of all three isozymes (except RH1 in the case of PFOA, where the increase was not statistically significant). 3. The correlations between hydrolase activities and isozyme contents supported specificity of the three substrates, with the exception that the content of the predominant isozyme, RL2, showed a higher correlation with BUTA hydrolase activity than with ISOC hydrolase activity. 4. In conclusion, we have demonstrated that metabolically-inert perfluorinated fatty acids induce hepatic microsomal carboxylesterase isozymes, as determined by radial immunodiffusion analysis using specific antibodies. This is the first report that perfluorinated fatty acid affect carboxylesterase isozymes in rat liver microsomes, and is indicative of the importance of peroxisome proliferators in hepatic metabolism of xenobiotics. Further work is needed to determine the regulatory mechanisms involved.

Acetanilides↗
PubMed1993

Metabolic fate of a new dihydropyridine calcium antagonist, CD-349, in rat and dog.

1. The metabolic fate of 14C-CD-349, a new calcium antagonist, was studied in rat and dog. 2. After oral administration of 14C-labelled drug in both species, the plasma levels of radioactivity reached maxima at 1-2 h and declined with elimination half-lives of 6-7 h. In both species, 71-85% of radioactivity was excreted in faeces and 17-27% in urine in 120 h. Biliary excretion in rat after oral doses amounted to 33%. 3. The low ratio of unchanged drug to total radioactivity in plasma suggested that CD-349 underwent rapid metabolism in both species. 4. Twenty-two metabolites were isolated and identified from dog urine and an incubation mixture with 9000 g rat liver supernatant. Principal routes of biotransformation of CD-349 were similar in both species, and involved: (1) oxidation of the dihydropyridine ring to the corresponding pyridine ring; (2) denitration of the nitrate ester; (3) hydrolysis of the carboxy ester to the carboxylic acid; and/or (4) oxidation of the side chain, although quantitative interspecies differences were observed.

Animals↗
PubMed1993

Effects of protein isolates from radish and spinach leaves on serum lipids levels in rats.

Radish and spinach leaf protein isolates (RLP and SLP, respectively) were prepared from chilled aqueous 0.2% sodium hydroxide extract of their leaves. The RLP and SLP, and those supplemented with methionine (RLP+Met and SLP+Met, respectively) to become equal to casein in methionine content, were compared with casein for their effects on serum cholesterol level in rats fed with a cholesterol-enriched diet for 14 days. Each protein isolate was incorporated into the cholesterol-enriched diet to provide a 15% protein level. RLP was extremely inferior to SLP and casein for body weight gain of rats, but that of rats fed with RLP+Met diet was almost equal to that of casein and SLP groups. The serum cholesterol level in rats fed with SLP and SLP+Met diets was significantly lower as compared with that of the casein-fed rats. Both the amounts of excreted cholesterol and bile acids were significantly higher in rats fed with the SLP and SLP+Met diets than that of the casein-fed rats. These results suggest that the hypocholesterolemic action of SLP may in part have been due to the inhibition of intestinal absorption of both cholesterol and bile acids. RLP+Met diet tended to decrease the serum cholesterol level as compared to casein diet, but the difference was not significant.

Amino Acids↗
PubMed1993

Tetrafibricin, a novel fibrinogen receptor antagonist. I. Taxonomy, fermentation, isolation, characterization and biological activities.

Tetrafibricin is a novel fibrinogen receptor antagonist produced by Streptomyces neyagawaensis NR0577. It was isolated from the culture broth by Diaion HP-21 adsorption, MeOH extraction, MCI GEL CHP-20P column chromatography, preparative HPLC and Toyopearl HW-40 SF column chromatography. The physico-chemical properties of tetrafibricin indicated that the structure of tetrafibricin is different from the known peptide fibrinogen receptor antagonists and closely related to the polyene macrolide antibiotics. Tetrafibricin strongly inhibited the binding of fibrinogen to its receptors with an IC50 of 46 nM. It also inhibited ADP-, collagen-, and thrombin-induced aggregation of human platelets with IC50s of 5.6, 11.0 and 7.6 microM, respectively.

Anti-Bacterial Agents↗
PubMed1993

Tetrafibricin, a novel fibrinogen receptor antagonist. II. Structural elucidation.

The structure of tetrafibricin, a novel and potent fibrinogen receptor antagonist isolated from the culture broth of Streptomyces neyagawaensis NR0577, was determined. Tetrafibricin has a unique structure containing primary amine, conjugated tetraenoic acid, and polyhydroxy functionalities that is biosynthetically related to the polyene macrolide antibiotics.

Anti-Bacterial Agents↗