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951.
The study aim was to develop a simple in vitro model for pharmacophysiological investigation of urinary bladder smooth muscles. Smooth muscle cells from guinea pig detrusor were dissociated, and the suspended cells were stimulated with carbachol (CCh), an acetylcholine receptor agonist. Cytosolic Ca2+ levels were determined using Fura 2 fluorescence and extracellular acidification rates were monitored by the Cytosensor microphysiometer. CCh dose-dependently increased cytosolic Ca2+ levels and extracellular acidification rates, with EC50 values of approximately 1 microM. Both the acetylcholine muscarinic receptor antagonist atropine and the M3 muscarinic receptor-preferring antagonist 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) inhibited the effects of CCh, three orders of magnitude more potently than the selective M2 muscarinic receptor antagonist, methoctramine. These data indicate the dominant role of M3 receptors in guinea-pig bladder but fail to show clear evidence of any functional role for M2 receptors. Since this finding agrees with a number of other studies using in vivo and in vitro models (1), cell suspensions such as these may prove to be simple tools for the pharmacological study of urinary bladder smooth muscle tissue. 相似文献
952.
A Imamura N Hanaki A Nakamura T Suzuki M Taniguchi T Kiba C Ueguchi T Sugiyama T Mizuno 《Plant & cell physiology》1999,40(7):733-742
His-Asp phosphorelays are evolutionary-conserved powerful biological tactics for intracellular signal transduction. Such a phosphorelay is generally made up of "sensor histidine (His)-kinases", "response regulators", and "histidine-containing (HPt) phosphotransmitters". In the higher plant, Arabidopsis thaliana, results from recent intensive studies suggested that His-Asp phosphorelays may be widely used for propagating environmental stimuli, such as phytohormones (e.g., ethylene and cytokinin). In this study, we first inspected extensively the occurrence of Arabidopsis response regulators in order to compile and characterize them. The results showed that this higher plant has, at least, 14 members of the family of response regulators that can be classified into two distinct subtypes (type-A and type-B), as judged from their structural designs, biochemical properties, and expression profiles. Comparative studies were conducted for each representative (ARR3 and ARR4 for type-A, and ARR10 for type-B). It was suggested that expression of the type-A response regulator is cytokinin-inducible, while that of the type-B response regulator appears to be not. Results from yeast two-hybrid analyses suggested that the type-B response regulator may have an ability to stably interact with a set of HPt phosphotransmitters (AHPs). These and other results will be discussed with special reference to the His-Asp phosphorelay signaling network in Arabidopsis thaliana. 相似文献
953.
The existence and distribution of mammosomatotrophs (MS cells) containing growth hormone (GH) and prolactin (PRL) in bovine adenohypophysis were detailed by a combined method of mirror sections and immunohistochemical staining. MS cells always occurred in bovine adenohypophysis but their number was low. In the midsagittal plane, the cells were observed in the hind dorsal, hind ventral and fore ventral region abundant in GH and PRL cells. Whereas, in the zona tuberalis where GH and PRL cells were less frequent, MS cells were not detected. MS cells were invariably solitarily distributed within mammotroph (PRL cell) clusters but not within somatotroph (GH cell) clusters. The proportion of MS cells declined as the ages proceeded and the appearance was spatially related to the arrangement of PRL cells. These findings indicated that, in bovine adenohypophysis, MS cells were differentially distributed and occurred in PRL cell clusters. The results strongly suggest that MS cells originate in GH cells pre-existed within PRL cell clusters with special reference to the functional activation of PRL cells. 相似文献
954.
955.
Toida T Maruyama T Ogita Y Suzuki A Toyoda H Imanari T Linhardt RJ 《International journal of biological macromolecules》1999,26(4):233-241
Glycosaminoglycans including dermatan sulphate, hyaluronan, heparan sulphate and heparin were chemically modified by O-sulphonation. By altering the reaction conditions, products having a different degree of O-sulphonation could be obtained. Glycosaminoglycan derivatives were prepared having no free hydroxyl groups, with sulphoester group/disaccharide unit ratios of 4.0 for dermatan sulphate and hyaluronan, and sulphoester and sulphamide group/disaccharide unit ratios of 4.22 and 4.88 for heparan sulphate and heparin, respectively. 1H NMR spectroscopy showed that the fully O-sulphonated hyaluronan derivative had a glucuronate residue with an altered conformation. Since glycosaminiglycans and their derivatives are often used as anticoagulant/antithrombotic agents, their anti-amidolytic activities were determined. The anti-factor IIa activity of fully O-sulphonated dermatan sulphate, hyaluronan and heparan sulphate ranged from 40 to 80 units/mg, while no anti-factor Xa activity of the fully O-sulphonated glycosaminoglycans was detected. These values are lower than those reported for low-molecular-weight heparins and are consistent with the requirement of an antithrombin III pentasaccharide binding site for anti-factor Xa activity. Interestingly, the anti-factor Xa of heparin is lost by chemical O-sulphonation. 相似文献
956.
957.
Facile enzymatic conversion of lactose into lacto-N-tetraose and lacto-N-neotetraose 总被引:1,自引:0,他引:1
Lacto-N-tetraose (Galbeta1 -3GlcNAcbeta1-3Galbeta1-4Glc, LNT) and lacto-N-neotetraose (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc, LNnT) were enzymatically synthesized by consecutive additions of GlcNAc and Gal residues to lactose. Lacto-N-triose II (GlcNAcbeta1-3Galbeta1-4Glc) was prepared first by the transfer of GlcNAc from UDP-GlcNAc to lactose by beta-1,3-N-acetylglucosaminyltransferase from bovine serum. The resulting lacto-N-triose II was converted into LNT and LNnT utilizing two kinds of beta-D-galactosidase-mediated transglycosylations. Thus, beta-D-galactosidase from Bacillus circulans ATCC31382 induced regioselective galactosyl transfer from o-nitrophenyl beta-D-galactoside to the OH-3" position of lacto-N-triose II, and commercially available beta-D-galactosidase from B. circulans to the OH-4" position of lacto-N-triose II. These convenient processes are suitable for large-scale preparations of LNT and LNnT. As another method, LNT was directly synthesized from lactose as an initial substance, utilizing lacto-N-biosidase (Aureobacterium sp. L-101)-mediated transglycosylation with Galbeta1-3GlcNAcbeta-pNP donor. 相似文献
958.
Suzuki T Kansaku N Kurosaki T Shimada K Zadworny D Koide M Mano T Namikawa T Matsuda Y 《Cytogenetics and cell genetics》1999,87(1-2):22-26
Using direct R-banding fluorescence in situ hybridization, we assigned five functional genes-growth hormone receptor (GHR), prolactin receptor (PRLR), spleen tyrosine kinase (SYK), aldolase B (ALDOB), and muscle skeletal receptor tyrosine kinase (MUSK)-to the chicken Z chromosome. SYK and MUSK were newly localized to the chicken Z chromosome in this study. GHR and PRLR were situated close to each other on the short arm of the chicken Z chromosome, as are their counterparts on human chromosome 5. SYK, MUSK, and ALDOB, which have been mapped to human chromosome 9, were localized to the long arm of the chicken Z chromosome. Thus, the present results indicate the presence of conserved synteny between the chicken Z chromosome and human chromosomes 5 and 9. Using the same method, four of the genes (GHR, PRLR, ALDOB, and MUSK) were assigned to the Japanese quail Z chromosome. The locations of these four Z-linked genes were conserved between chicken and Japanese quail. The results support the notion that the avian Z chromosome and the mammalian X chromosome did not evolve from a common ancestral linkage group. 相似文献
959.
Effects of Chronic Administration of Interferon α A/D on Serotonergic Receptors in Rat Brain 总被引:7,自引:0,他引:7
The effects of chronic administration of interferon (IFN; recombinant human IFN -A/D) on serotonergic binding sites in rat brain were investigated. IFN was injected daily for 2 weeks at a dose of 100000 I.U./kg, (i.p.) in male Wistar rats. IFN did not alter either [3H]ketanserin binding to 5-HT2A receptors or [3H]paroxetine binding to 5-HT transporters. Scatchard analysis of [3H]8-hydroxy-dipropylaminotetraline (8-OH-DPAT) binding to 5-HT1A receptors demonstrated the presence of high- and low-affinity binding sites in both treatment and control groups. IFN significantly increased both Kd and Bmax measures of [3H]8-OH-DPAT binding at low-affinity binding sites, but not at the high-affinity sites. These results suggest that IFN affects the low-affinity 5-HT1A receptors sites and may be involved in the development of IFN-induced psychiatric disturbances. 相似文献
960.
Relationships between ovarian structure, oocyte structure/development, and parental care/life history strategies of six loricariid catfishes common in the upper Paraná River, Brazil were examined with analysis of catch data, relative gonad weight, histology, and microscopy. Three life history strategies were observed. Loricariichthys platymetopon , Loricariichthys sp. And Loricaria sp. produce several small clutches of large eggs over a protracted spawning period. Males of these species guard their eggs and larvae, which are transported as a mass on the ventral surface of the male's body. Hypostomus ternetzi and Megalancistrus aculeatus produce the largest mature eggs and the smallest clutches relative to adult mass. The spawning periods of these species are short, and males guard their broods in excavations. Rhinelepis aspera has high fecundity, high relative mass of mature gonads (both sexes), small mature eggs, and broadcast spawning with no parental care. This species migrates to spawn over firm substrates in channel areas during a contracted period. Mature oocytes of external bearers had the thickest zona radiata, followed by the egg scatterer, and cavity nesters. The thickness of the zona radiata probably is an adaptation to protect the developing egg from injury from abrasion. The zona granulosa appeared to be associated with production of secretions responsible for egg adhesion, and this layer was thickest in mature oocytes of the cavity nesting species, followed by the external bearers. All six species have wide distributions in the Paraná River, tributaries, floodplain lagoons, and the Itaipu Reservoir, but brood guarders tended to be most common in lentic habitats. 相似文献