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Y Ohizumi

Publications and source records attributed to Y Ohizumi.

At least 19 recordsLinked to original sources
PubMed2001

Preconditioning of 3T3 cells by fresh medium together with genistein enhances prostaglandin E(2) release.

Bradykinin induced prostaglandin E(2) release from the Swiss 3T3 fibroblasts, preconditioned with fresh culture medium. Although treatment with genistein for the entire period of preconditioning and incubation with bradykinin attenuated prostaglandin E(2) release, treatment with fresh culture medium and genistein for only the preconditioning period further augmented the prostaglandin E(2) release. In the cells preconditioned with fresh culture medium and genistein, bradykinin caused the phosphorylation of protein tyrosine and mitogen-activated protein kinase/extracellular-regulated kinase (MAPK/ERK), followed by arachidonic acid release. Interestingly, preconditioning with genistein alone also caused phosphorylation and arachidonic acid release, probably reflecting rebound activation after the washout of genistein. However, preconditioning with genistein alone induced neither the augmentation of prostaglandin E(2) release nor the expression of cyclooxygenase-2. The further potentiation of bradykinin-induced prostaglandin E(2) release by combined preconditioning with fresh culture medium and genistein may be due to the activation of the MAPK/ERK-c phospholipase A(2) pathway by preconditioning with genistein.

3T3 Cells↗
PubMed2001

Novel marine-derived halogen-containing gramine analogues induce vasorelaxation in isolated rat aorta.

We examined the effects of 2,5,6-tribromo-1-methylgramine (TBG), isolated from bryozoan, and its derivative, 5,6-dibromo-1,2-dimethylgramine (DBG), on the contraction of rat aorta. TBG and DBG decreased the high-K(+)-induced increase in muscle contraction and cytosolic Ca(2+) level ([Ca(2+)](i)), respectively. The inhibitory effects of TBG and DBG on high-K(+)-induced contraction were antagonized by increasing the external Ca(2+) concentration or by 1,4-dihydro2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]pyridine-3-carboxylic acid (Bay k8644). The high-K(+)-induced increase of Mn(2+) influx was completely blocked by 10 microM TBG or 10 microM DBG. In the Ca(2+)-free solution, 30 microM TBG or 30 microM DBG inhibited the phenylephrine-induced transient increase in [Ca(2+)](i) and muscle tension, while scarcely affecting caffeine-induced transient changes. TBG and DBG significantly increased the cyclic AMP content at 30 microM, but not at 10 microM. These results suggest that TBG and DBG inhibit the smooth muscle contraction by inhibiting Ca(2+) entry, and at higher concentrations, the increase in intracellular cyclic AMP content also contributes to their inhibitory effect.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2001

Pharmacological studies of geissoschizine methyl ether, isolated from Uncaria sinensis Oliv., in the central nervous system.

The pharmacological properties of geissoschizine methyl ether, isolated from Uncaria sinensis Oliv., were analyzed in vitro and in vivo using mice central serotonin neurons. In the in vitro experiment, geissoschizine methyl ether inhibited [3H]8-hydroxy-2-(di-n-propylamino)tetralin) ([3H]8-OH-DPAT) (K(i)=0.8 microM), [3H]mesulergine (K(i)=0.9 microM) and [3H]ketanserin (K(i)=1.4 microM), but had less affinity toward [3H]prazosin (K(i) > 10 microM) and [3H]spiperone (K(i) >15 microM) binding to mouse brain membranes. The in vivo studies showed that geissoschizine methyl ether dose-dependently reduced 5-hydroxy-L-tryptophan (I-5-HTP) plus clorgyline-induced head twitch response without inhibiting the I-5-HTP plus clorgyline and 8-OH-DPAT-induced head weaving. On the other hand, geissoschizine methyl ether also decreased the rectal temperature of mice (hypothermic response) in a dose-dependent manner. These results suggest that geissoschizine methyl ether possesses mixed 5-HT(1A) receptor agonist/5-HT(2A/2C) receptor antagonist activities and inhibits the head twitch response by blocking the 5-HT(2A) receptors, and possibly, at least in part, by stimulating the 5-HT(1A) receptors in the central nervous system.

5-Hydroxytryptophan↗
PubMed2001

Halenaquinone, a novel phosphatidylinositol 3-kinase inhibitor from a marine sponge, induces apoptosis in PC12 cells.

In nerve growth factor-treated PC12 cells, 12b-methyl-(S)-1H-benzo[6,7]phenanthro[10,1-bc]furan-3,6,8,11(2H,12bH)-tetrone (halenaquinone) caused cytotoxicity in a concentration-dependent manner (EC(50) value; 10 microM). Gel electrophoretic DNA analysis of PC12 cells treated with halenaquinone (10 microM) and 11-(acetyloxy)-1,6b,7,8,9a,10,11,11b-octahydro-1-(methoxymethyl)-9a,11b-dimethyl-[1S-(1 alpha,6b alpha,9a beta,11 alpha,11b beta)]-3H-furo[4,3,2-de]indeno[4,5-h]-2-benzopyran-3,6,9-trione (wortmannin) (3 microM) showed a typical apoptotic DNA ladder. In the flow cytometric analysis, halenaquinone caused apoptosis in a concentration- and time-dependent manner (EC(50) value; 10 microM), whereas 2,3-dihydro-12b-methyl-(S)-1H-benzo[6,7]phenanthro[10,1-bc]furan-6,8,11(12bH)-trione (xestoquinone) with the methylene group at the C-3 position failed to cause apoptosis, suggesting that the carbonyl group at the C-3 position in halenaquinone is important for exerting apoptotic effects in PC12 cells. Phosphatidylinositol 3-kinase was inhibited by halenaquinone (IC(50) value; 3 microM) as well as wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase. Halenaquinone inhibited phosphatidylinositol 3-kinase activity at lower concentrations than those at which it induced apoptosis in PC12 cells. These results suggest that halenaquinone causes the death of PC12 cells through an apoptotic process and that the mechanism of halenaquinone-induced apoptosis may be partially explained by the inhibition of phosphatidylinositol 3-kinase activity.

Acetylcysteine↗
PubMed2001

Intraoperative radiation therapy for curatively resected rectal cancer.

PURPOSE: Intraoperative radiotherapy has been used for local control of locally advanced rectal cancer. The aim of this study was to investigate the efficacy of intraoperative radiotherapy for curatively resected rectal cancer. METHODS: Between 1982 and 1998, intraoperative radiotherapy was administered in combination with curative resection in 78 patients with adenocarcinoma of the middle or lower third of the rectum (intraoperative radiotherapy group). Sixty-two of the patients had received preoperative radiotherapy with 20 Gy. Intraoperative radiotherapy was performed by a new strategy in which an electron beam was administered as uniformly as possible to the entire dissected surface of the pelvis. Retrospective comparisons were made with 248 patients treated by surgery alone during the same period (non-intraoperative radiotherapy group). RESULTS: The differences in tumor stage or surgical procedures between the two groups were not statistically significant. Survival, disease-free survival, and local recurrence-free survival in the intraoperative radiotherapy group were significantly more favorable than in the non-intraoperative radiotherapy group (P = 0.01, P = 0.04, and P = 0.02). Differences in survival were observed in Stage II patients but not in Stage I or Stage III patients. The local failure rate was 2.6 percent in the intraoperative radiotherapy group and 11.3 percent in the non-intraoperative radiotherapy group, and the difference was significant (P = 0.02). The distant metastasis rate was 18.0 percent in the intraoperative radiotherapy group and 19.5 percent in the non-intraoperative radiotherapy group, and the difference was not significant. There was a significantly higher rate of wound infection in the intraoperative radiotherapy group, but no infections were serious. CONCLUSIONS: In patients with adenocarcinoma of the middle or lower third of the rectum, intraoperative radiotherapy to the entire dissected surface of the pelvis reduced local recurrence in Stage II and Stage III patients and improved survival in Stage II patients.

Adenocarcinoma↗
PubMed2001

Verbenachalcone, a novel dimeric dihydrochalcone with potentiating activity on nerve growth factor-action from Verbena littoralis.

A novel dimeric dihydrochalcone, verbenachalcone (1), was isolated from the aerial parts of Verbena littoralis. Its structure was elucidated, on the basis of spectral data interpretation, as 4,2',4',2' ",4' "-pentahydroxy-3' '-methoxy-3-O-4' '-tetrahydrobichalcone. This compound caused a significant enhancement of nerve growth factor-mediated neurite outgrowth from PC12D cells.

Animals↗
PubMed2001

Scabronine G-methylester enhances secretion of neurotrophic factors mediated by an activation of protein kinase C-zeta.

Glial cells release neurotrophic factors that maintain neurons functionally. Previously, we have shown that the scabronines isolated from Sarcodon scabrosus enhanced the secretion of neurotrophic factors from 1321N1 human astrocytoma cells. In the present study, we examined the mechanism of newly synthesized scabronine G-methylester (ME)-induced secretion of neurotrophic factors from 1321N1 cells. The dramatic neuronal differentiation of rat pheochromocytoma cells (PC-12) was observed by scabronine G-ME-conditioned medium of 1321N1 cells. Scabronine G-ME increased the secretion of nerve growth factor (NGF) and interleukin-6 (IL-6) from 1321N1 cells with the enhancement of their mRNA expressions. Scabronine G-ME concentration-dependently inhibited the carbachol-induced inositol phosphate accumulation in 1321N1 cells, which was reversed by GF109203X, an inhibitor of protein kinase C (PKC) isoforms. Furthermore, GF109203X inhibited the scabronine G-ME-induced mRNA expressions of both NGF and IL-6 and the differentiation of PC-12 cells, showing that scabronine G-ME activated PKC. Although scabronine G-ME enhanced activities of neither conventional nor novel types of PKCs, it translocated PKC-zeta to membranes in intact cells and cell-free condition. Furthermore, recombinant PKC-zeta activity was also increased by scabronine G-ME, suggesting the involvement of PKC-zeta in the effect of scabronine G-ME. Concerning the downstream effectors of the PKC-zeta, scabronine G-ME translocated nuclear factor-kappaB to nucleus, and enhanced its transcriptional activity. In addition, scabronine G-ME caused the degradation of inhibitor of nuclear factor-kappaB concentration-dependently, which was inhibited by GF109203X. These results suggest that scabronine G-ME potentially enhances the secretion of neurotrophic factors from 1321N1 cells mediated via the activation of PKC-zeta.

Animals↗
PubMed2001

Potentiation of nerve growth factor-induced elongation of neurites by gelsemiol and 9-hydroxysemperoside aglucone in PC12D cells.

In PC12D cells, nerve growth factor (NGF) increased the proportion of neurite-bearing cells and made neurites longer. A methanol extract of Verbena littoralis H. B. K. collected in Paraguay only slightly potentiated the proportion of PC12D cells with neurites but markedly increased the length of neurites in the presence of NGF (2 ng mL(-1)). The methanol extract was partitioned between ethyl acetate and water followed by further extraction of water fraction with n-butanol. The potentiating activity of NGF-action was observed in the ethyl acetate and n-butanol fractions. The n-butanol fraction was separated by silica gel chromatography, monitoring the NGF-potentiating activity to give gelsemiol and 9-hydroxysemperoside aglucone (9-OHSA). Neither compound (30-300 microM) exhibited neurite-inducing activity alone. Gelsemiol (100-300 microM) markedly enhanced an increase in the proportion of neurite-bearing cells and an extension of the neurite length in the presence of NGF (2 ng mL(-1)). Interestingly, in the presence of NGF (2 ng mL(-1)), 9-OHSA (100-300 microM) enhanced the elongation of neurites without affecting the increase in the proportion of cells with neurites. These results suggested that gelsemiol and 9-OHSA were major active components of V. littoralis in the NGF-potentiating action. It was possible that the mechanism of neurite elongation by NGF was different from that of the increase in the proportion of neurite-bearing cells, and that 9-OHSA selectively affected the neurite elongation mechanism.

Cell Culture Techniques↗
PubMed2001

Two new monoterpene peroxide glycosides from Aster scaber.

The aerial part of Aster scaber Thunb. (Asteraceae) yielded two new monoterpene peroxide glycosides, (3S)-3-O-(3',4'-diangeloyl-beta-D-glucopyranosyloxy)-7-hydroperoxy-3,7-dimethylocta-1,5-diene (1) and (3S)-3-O-(3',4'-diangeloyl-beta-D-glucopyranosyloxy)-6-hydroperoxy-3,7-dimethylocta-1,7-diene (2), and five known compounds, alpha-spinasterol (3), germacra-4(15),5,10(14)-triene-1-beta-ol (4), 7-methoxy-4(15)-oppositen-1-beta-ol (5), 6alpha-methoxy-4(15)-eudesmane-1beta-ol (6) and alpha-spinasterol 3-O-beta-D-glucopyranoside (7). The structures were established by chemical and spectroscopic methods.

Asteraceae↗
PubMed2001

Imaging of Ca2+ release by caffeine and 9-methyl-7-bromoeudistomin D and the associated activation of large conductance Ca2+-dependent K+ channels in urinary bladder smooth muscle cells of the guinea pig.

Ca2+ release by caffeine and 9-methyl-7-bromoeudistomin D (MBED) and the concomitant activation of large conductance Ca2+-dependent K+ (BK) channels were analyzed using confocal Ca2+ imaging and whole cell voltage-clamp methods in guinea pig urinary bladder smooth muscle cells. Puff application of 3 or 10 mM caffeine for several seconds (2 - 5 s) elicited a large increase in intracellular Ca2+ concentration ([Ca2+]i) and induced a phasic outward current at a holding potential of -40 mV. The phasic outward current was the summation of spontaneous transient outward currents (STOCs) due to marked activation of BK channels and was followed by a short cessation of STOCs. Although the increase in superficial [Ca2+]i by caffeine was faster than that in global [Ca2+]i, the peak [Ca2+]i was identical in these areas. Puff application of 100 microM MBED also markedly enhanced STOCs for a few seconds. This response to MBED was not observed when stored Ca2+ was depleted by caffeine. The increase in [Ca2+]i by MBED occurred mainly in superficial areas. Longer application of 100 microM MBED for 2 min did not induce significant global [Ca2+]i increase but decreased the amount of Ca2+ release and cell shortening during the subsequent application of 10 mM caffeine. These results indicate that short application of MBED releases Ca2+ preferentially from superficial storage sites, presumably due to its slow approach to deeper sites. MBED may be a good pharmacological tool to manipulate selectively the superficial Ca2+ stores related to STOCs.

Animals↗
PubMed2001

Two steroidal saponins from Camassia cusickii induce L1210 cell death through the apoptotic mechanism.

Two steroidal saponins, tigogenin hexasaccharide-1 (TGHS-1, (25R)-5alpha-spirostan-3beta-yl 4-O-[2-0-[3-O-(alpha-L-rhamnopyranosyl)-beta-D-glucopyranosyl]-3-0-[4-0- (alpha-L-rhamnopyranosyl)-beta-D-glucopyranosyl]-beta-D-glucopyranosyl]-3-D- galactopyranoside) and tigogenin hexasaccharide-2 (TGHS-2, (25R)-5alpha-spirostan-3beta-yl 4-O-[2-0-[3-0-(beta-D-glucopyranosyl)-beta-D-glucopyranosyl]-3-0-[4-0- (alpha-L-rhamnopyranosyl)-beta-D-glucopyranosyl]-beta-D-glucopyranosyl]beta-D-galactopyranoside), were isolated from the fresh bulbs of Camassia cusickii. In murine leukemic L1210 cells, both compounds showed cytotoxicity with an EC50 value of 0.06 microM. The morphological observation revealed that TGHS-1 and TGHS-2 induced shrinkage in cell soma and chromatin condensation, suggesting apoptotic cell death. The cell death was confirmed to be apoptosis by Annexin V binding to phosphatidylserine in the cell membrane and excluding propidium iodide. A typical apoptotic DNA ladder and the cleavage of caspase-3 were observed after treatment with TGHS-1 and TGHS-2. In the presence of both the compounds, cells with sub-G1 DNA content were detected by flow cytometric analysis, indicating that TGHS-1 and TGHS-2 (each EC50 value of 0.1 microM) are the most powerful apoptotic saponins known. These results suggest that TGHS-1 and TGHS-2 induce apoptotic cell death through caspase-3 activation.

Animals↗
PubMed2000

Potentiation of nerve growth factor-action by picrosides I and II, natural iridoids, in PC12D cells.

Natural iridoid, picroside I (beta-D-glucopyranoside, 1a,1b,2,5a,6, 6a-hexahydro-6-hydroxy-1a-(hydroxymethyl)oxireno[4,5]cyclopenta[1, 2-c]pyran-2-yl, 6-(3-phenyl-2-propenoate)) or II (beta-D-glucopyranoside, 1a,1b,2,5a,6, 6a-hexahydro-6-[(4-hydroxy-3-methoxybenzoyl)oxy]-1a-(hydroxymethyl )ox ireno[4,5]cyclopenta[1,2-c]pyran-2-yl) alone did not exhibit neuritogenic activity, but caused a concentration-dependent (>0.1 microM) enhancement of nerve growth factor (NGF, 2 ng/ml)-induced neurite outgrowth from PC12D cells. The picroside-induced enhancing action of NGF was abolished by GF109203X (2-[1-(3-dimethylaminopropyl)-indol-3-yl]-3-(indol-3-yl)maleimide) (0.1 microM), a protein kinase C inhibitor. Furthermore, PD98059 (2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one) (20 microM), a potent mitogen-activated protein (MAP) kinase kinase inhibitor, completely blocked the picroside-induced enhancement of neurite outgrowth in the presence of NGF (2 ng/ml), suggesting that picrosides activate the MAP kinase-dependent signaling pathway. Interestingly, no increase in the expression of phosphorylated MAP kinase was observed in picroside-treated (60 microM) PC12D cells in the presence of NGF (2 ng/ml). These results suggest that picroside I or II enhances NGF-induced neurite outgrowth from PC12D cells, probably by amplifying a down-stream step of MAP kinase in the NGF receptor-mediated intracellular MAP kinase-dependent signaling pathway.

Animals↗
PubMed2000

Differentiation of rat pheochromocytoma cells by fomitellic acids, specific DNA polymerase inhibitors.

Fomitellic acid (FA) A and B are specific inhibitors of DNA polymerase alpha and beta. They showed cytotoxicity against rat pheochromocytoma cells (PC-12 cells) in a concentration-dependent manner. However, after PC-12 cells were cultivated with low concentrations of FAs, the cells extended neurites in greater degree similar to the cells cultivated with nerve growth factor. Another DNA polymerase alpha inhibitor, aphidicolin, also induced neurite outgrowth. Furthermore, PC-12 cells were strongly immunostained with anti-alpha-tubulin or anti-tau antibody after the treatment with FAs. These results suggest that weak inhibition of DNA polymerase activity induces the neurite outgrowth in PC-12 cells.

Animals↗
PubMed2000

Thromboxane A2 receptor-mediated tonic contraction is attributed to an activation of phosphatidylcholine-specific phospholipase C in rabbit aortic smooth muscles.

Thromboxane A2 (TXA2) analogue STA2 produced a tonic contraction in rabbit aortic smooth muscles. In the present study, we examined phosphatidylcholine (PC) hydrolysis as a signaling pathway for the tonic contraction in rabbit aortic smooth muscles. In the primary cultured cells labeled with [3H]choline, STA2 caused an accumulation of [3H]phosphorylcholine, a metabolite of PC by PC-specific PLC, in a concentration-dependent manner. The accumulation of [3H]phosphorylcholine was inhibited by SQ29548, a TXA2 receptor antagonist. In the muscle strips, STA2-induced tonic contraction was potently inhibited by D609, an inhibitor of PC-specific phospholipase C in a concentration-dependent manner with the IC50 of about 10 microM. Norepinephrine-induced tonic contraction was also inhibited by D609 with a weaker potency. These results strongly suggest that stimulation of TXA2 receptor results in the activation of PC-specific phospholipase C to yield diacylglycerol that contributes to the tonic contraction.

Animals↗
PubMed2000

Involvement of phosphatidylcholine-specific phospholipase C in thromboxane A2-induced activation of mitogen-activated protein kinase in astrocytoma cells.

Thromboxane A2 (TXA2) receptor-mediated signal transduction was investigated in 1321N1 human astrocytoma cells. 9,11-Epithio-11,12-methano-TXA2 (STA2), a TXA2 receptor agonist, induced Ca2+ mobilization and phosphoinositide hydrolysis in a concentration-dependent manner. These responses were inhibited by treatment with U73122, an inhibitor of phosphatidylinositol-specific phospholipase C, or by culturing in 0.5% fetal calf serum containing 0.5 mM dibutyryladenosine 3',5'-cyclic monophosphate (dbcAMP) for 2 days. However, the dbcAMP treatment augmented the TXA2 receptor-mediated phosphorylation of mitogen-activated protein kinase (MAPK). These results were confirmed by a functional MAPK assay measuring the incorporation of 32P into the MAPK substrate peptide. The TXA2 receptor-mediated MAPK activation was inhibited by SQ29548, a TXA2 receptor antagonist, and GF109203X, an inhibitor of protein kinase C. Although U73122 did not inhibit or only slightly inhibited the activation of MAPK, D-609, an inhibitor of phosphatidylcholine-specific phospholipase C, potently attenuated the activation in a concentration-dependent manner. Furthermore, STA2 accelerated the release of [3H]choline metabolites from the cells prelabeled with [3H]choline chloride. This release was inhibited by treatment with D-609. These results suggest that phosphatidylcholine-specific phospholipase C and protein kinase C, but not phosphatidylinositol-specific phospholipase C, are involved in TXA2 receptor-mediated MAPK activation in 1321N1 human astrocytoma cells.

Calcium↗
PubMed2000

Structure-activity relationships for the Ca2+-releasing activity of 6-hydroxy-beta-carboline analogues in skeletal muscle sarcoplasmic reticulum-the effects of halogen substitution at C-5 and C-7.

This study of structure-activity relationships of 6-hydroxy-beta-carboline analogues has been performed on the basis of quantitative measurement of Ca2+-releasing activity in the sarcoplasmic reticulum of skinned fibres of skeletal muscle. Substitution of halogens for hydrogens at the C-5 and C-7 positions and further introduction of a methyl group into the N-9 position of 6-hydroxy-beta-carboline resulted in Ca2+-releasing activity. The 50% effective concentrations of 5,7-dibromoeudistomin D, 5,7-dichloroeudistomin D, 5,7-diiodoeudistomin D, 9-methyl-5,7-dibromoeudistomin D, 9-methyl-5,7-dichloroeudistomin D, 9-methyl-5,7-diiodoeudistomin D, and caffeine were 5.6 x 10(-6), 6.3 x 10(-6), 7.8 x 10(-6), 2.1 x 10(-6), 2.0 x 10(-5), 3.7 x 10(-5), and 4.7 x 10(-4) M, respectively, indicating that these analogues are 10-200 times more potent than caffeine. Substitution of bromine by chlorine or iodine at the C-5 and C-7 positions markedly reduced the activity of the analogues with a methyl group at the N-9 position. These results suggest that halogens at the C-5 and C-7 positions in the beta-carboline skeleton are essential for Ca2+-releasing activity and that an N-9 methyl group also affects the activity of these analogues. Thus, these 6-hydroxy-beta-carboline analogues might become powerful tools for studying the molecular mechanism of Ca2+ release in the sarcoplasmic reticulum.

Animals↗