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31.
The inhibition of forskolin-stimulated adenylate cyclase activity by 5-hydroxytryptamine (5-HT) receptor agonists was measured in rat hippocampal membranes isolated from animals treated with vehicle or islet-activating protein (IAP; pertussis toxin). In vehicle-treated animals, 5-HT, 8-hydroxy-2-(di-n-propylamino)tetralin, buspirone, and gepirone were potent in inhibiting forskolin-stimulated adenylate cyclase activity with EC50 values of 60, 76, 376, and 530 nM, respectively. IAP treatment reduced by 30-55% the 5-HT1A agonist inhibition of adenylate cyclase activity via 5-HT1A receptors. The data indicate that the inhibitory guanine nucleotide-binding protein or Go (a similar GTP-binding protein of unknown function purified from brain) mediates the 5-HT1A agonist inhibition of hippocampal adenylate cyclase. 相似文献
32.
Hidetaka Kosako Yukiko Gotoh Eisuke Nishida 《Development, growth & differentiation》1996,38(6):577-582
Mitogen-activated protein kinase (MAPK) was originally identified as a serine/threonine protein kinase that is rapidly activated in response to various growth factors and tumor promoters in mammalian cultured cells. The kinase cascade including MAPK and its direct activator, MAPK kinase (MAPKK), is now believed to transmit various extracellular signals into their intracellular targets in eukaryotic cells. It has been reported that activation of MAPKK and MAPK occurs during the meiotic maturation of oocytes in several species, including Xenopus laevis . Studies with neutralizing antibodies against MAPKK, MAPK phosphatases and constitutively active MAPKK or MAPK have revealed a crucial role of the MAPKK/MAPK cascade in a number of developmental processes in Xenopus oocytes and embryos. 相似文献
33.
Lentinan, a -1,6;1,3-glucan, is tumor-specific for transplantable mouse solid-type tumors and it also stimulates the production of acute phase proteins (APPs). The APP response to lentinan is of the delayed type (DT-APR) and differs from that to lipopolysaccharide, which is acute. We found that the responses were genetically controlled in mice and that low responsiveness is dominant (Maeda et al. 1991). Using 123 segregants of crosses between SWR/J (a high responder) andMus spretus (a low responder), we analyzed the linkage between DT-APR responsiveness and the DNA polymerase chain reaction-simple sequence lenght polymorphism (PCR-SSLP) phenotype using 80 chromosome-specific microsatellite markers. We identified two loci (ltn1.1 andltn1.2) responsible for DT-APR.ltn1.1 is closely linked toD3Mit11 on chromosome 3 andltn1.2 toD11Nds9 on chromosome 11 (P<0.001). The linkage analysis also suggested thatltn1.2 is the major determinant for DT-APR. Correlation between lentinan-specific IL-6 mRNA expression (the late expression) controlled recessively and DT-APR induction suggests that theltn1 loci control some process(es) of IL-6 expression in the regulation step before NF-IL6. 相似文献
34.
Kenichiro Nakashima Naotaka Kuroda Shinki Kawaguchi Mitsuhiro Wada Shuzo Akiyama 《Luminescence》1995,10(3):185-191
A sensitive peroxyoxalate chemiluminescent (PO-CL) assay for activities of oxidases (uricase, choline oxidase, cholesterol oxidase and xanthine oxidase) which catalyse a formation of hydrogen peroxide was developed using 4,4′-oxalyl-bis[(trifluoromethylsulphonyl)imino]trimethylene-bis(4-methylmorpholinium)trifluoromethanesulphonate as a chemiluminogenic reagent and 2,4,6,8-tetramorpholinopyrimido[5,4-d]pyrimidine as a fluorophore. The standard curve for hydrogen peroxide was linear over the range 1 × 10?7-1 × 10?4 mol/L. Relative standard deviations for oxidase assays were 5.1–12.7% (n = 10). Detection limits were 1 × 10?3 U/mL for uricase, 5 × 10?4 U/mL for choline oxidase, 5 × 10?3 U/mL for cholesterol oxidase and 5 × 10?4 U/mL xanthine oxidase (sample to blank ratio, 3). 相似文献
35.
36.
Kazuo Yamamoto Chizu Ishida Mitsue Saito Yukiko Konami Toshiaki Osawa Tatsuro Irimura 《Glycoconjugate journal》1994,11(6):572-575
Maackia amurensis haemagglutinin (MAH) is a leguminous lectin which preferentially binds to a cluster of sialylatedO-linked carbohydrate chains (Konami Y, Yamamoto K, Osawa T, Irimura T (1994)FEBS Lett
342:334–38). In the present study a 950 bp cDNA clone encoding MAH was isolated from a cDNA library constructed from germinatedMaackia amurensis seeds. From the nucleotide sequence, MAH was predicted to consist of 285 amino acid residues containing a signal peptide of 29 amino acids. The results also confirmed our previous findings from the amino acid sequence analysis, which indicated that two highly conserved amino acid residues in all other well-known leguminous lectins were replaced in MAH. These residues were lysine-105 and aspartic acid-135. The corresponding amino acid residues in other leguminous lectins were glycine and asparagine, respectively. These differences were due to the presence of nucleotides AAA and GAT in place of AAT/C and GGA/T.Abbreviations MAH
Maackia amurensis haemagglutinin. 相似文献
37.
Antioxidant Properties of Bromocriptine, a Dopamine Agonist 总被引:3,自引:1,他引:2
Toshikazu Yoshikawa† Yukiko Minamiyama Yuji Naito Motoharu Kondo 《Journal of neurochemistry》1994,62(3):1034-1038
Abstract: It has been suggested that free radicals may adversely influence the pathogenesis of Parkinson's disease. We conducted this study to determine whether bro-mocriptine, an agent widely used for treating parkinsonism, possesses antioxidant effects. Bromocriptine scavenged superoxide produced from a superoxide generating system (hypoxanthine-xanthine oxidase) by the spin-trapping method using electron spin resonance. Bromocriptine had a strong scavenging effect on the 5,5-dimethyl-1-pyrroline- N -oxide hydroxide signal produced from Fenton's reaction. Bromocriptine also attenuated the stable free radical diphenyl- p -picrylhydrazyl signal. This drug inhibited the autooxidation of rat brain homogenates in a dose-dependent manner in vitro. Autooxidation of brain homogenates collected from rats treated with bromocriptine (2.5 mg/kg, i.p., daily for 3 days) was significantly reduced as compared with values in untreated rat homogenates. These observations suggest that bromocriptine is a free radical scavenger and a potent antioxidant. 相似文献
38.
39.
The correlation between active oxygens scavenging and antioxidative effects of flavonoids 总被引:13,自引:0,他引:13
The abilities of 15 flavonoids as a scavenger of active oxygens (hydroxyl radical and superoxide anion) were studied. Hydroxyl radical (.OH) was generated by the Fenton system, and assayed by the determination of methanesulfinic acid (MSA) formed from the reaction of dimethyl sulfoxide (DMSO) with .OH. (+)-Catechin, (−)-epicatechin, 7,8-dihydroxy flavone, and rutin showed the .OH scavenging effect 100–300 times superior to that of mannitol, a typical .OH scavenger. The other flavonoids showed no .OH scavenging effect at their concentrations up to 50 μM. Baicalein, quercetin, morin, and myricetin unexpectedly increased the .OH production in the Fenton system. The flavonoids tested now, except monohydroxy flavones, were more or less inhibitive to the superoxide anion (O2) generation in the hypoxanthine-xanthine oxidase system. A great part of this inhibitory effect was likely owing to suppression of xanthine oxidase activity by the flavonoids. The flavonoids, which scavenged .OH or O2−, were necessarily antioxidants to the peroxidation of methyl linoleate. However, there was a type of flavonoid such as morin, which have neither .OH nor O2− scavenging effect, but was a strong antioxidant. 相似文献
40.
Sakamoto Atsushi; Ohsuga Hiroyuki; Wakaura Makoto; Mitsukawa Norihiro; Hibino Takashi; Masumura Takehiro; Sasaki Yukiko; Tanaka Kunisuke 《Plant & cell physiology》1993,34(6):965-968
A cDNA clone for copper/zinc-superoxide dismutase (Cu/Zn-SOD)was isolated from spinach (Spinacia oleracea L.) leaves. Itsnucleotide sequence showed that it codes for a precursor polypeptideof 222 amino acids, including the NH2-terminal 68-residue extensionwhich corresponds to a plastidic transit peptide. Northern hybridization,using plastidic and cytosolic Cu/Zn-SOD cDNAs as the probes,revealed that these two genes are differentially expressed inthe roots and leaves of spinach.
1Present address: Department of Biochemistry and Microbiology,Cook College, Rutgers University New Brunswick, NJ 08903-0231,U.S.A. 相似文献