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排序方式: 共有1542条查询结果,搜索用时 250 毫秒
61.
Ishibashi K Miura NN Adachi Y Tamura H Tanaka S Ohno N 《FEMS immunology and medical microbiology》2004,42(2):155-166
We have recently demonstrated that the cell wall beta-glucan of Candida albicans could be solubilized by sodium hypochlorite, followed by dimethylsulfoxide-extraction (NaClO-DMSO method). In this study, applying this method to Aspergillus spp., we prepared mycelial cell wall beta-glucan and examined its physical properties and immunotoxicological activity. The acetone-dried mycelia of Aspergillus spp. were oxidized by the NaClO-DMSO method. An analysis of (13)C NMR spectra revealed the preparations to be composed of alpha-(1 --> 3) and beta-(1 --> 3)-D-glucan. Also, the proportion of alpha-(1 --> 3) and beta-(1 --> 3)-D-glucan varied. Furthermore, a solubilized Aspergillus beta-glucan (ASBG) was prepared from OX-Asp by urea-autoclave treatment. ASBG showed limulus activity similar to Candida solubilized beta-glucan (CSBG), and there was little difference in the activity of ASBG between various Aspergillus spp. ASBG affected the production of IL-8 by human peripheral blood mononuclear cells (PBMC). ASBG should be useful for analyzing the clinical role of beta-glucan. 相似文献
62.
Soeda S Tsuji Y Ochiai T Mishima K Iwasaki K Fujiwara M Yokomatsu T Murano T Shibuya S Shimeno H 《Neurochemistry international》2004,45(5):619-626
Magnesium-dependent neutral sphingomyelinase (N-SMase) present in plasma membranes is an enzyme that can be activated by stress in the form of inflammatory cytokines, serum deprivation, and hypoxia. The design of small molecule N-SMase inhibitors may offer new therapies for the treatment of inflammation, ischemic injury, and cerebral infarction. Recently, we synthesized a series of difluoromethylene analogues (SMAs) of sphingomyelin. We report here the effects of SMAs on the serum/glucose deprivation-induced death of neuronally differentiated pheochromocytoma (PC-12) cells and on cerebral infarction in mice. SMAs inhibited the enhanced N-SMase activity in the serum/glucose-deprived PC-12 cells, and thereby suppressed the apoptotic sequence: ceramide formation, c-Jun N-terminal kinase phosphorylation, caspase-3 activation, and DNA fragmentation in the nuclei. Administration of SMA-7 (10 mg/kg i.v.) with IC50= 3.3 microM to mice whose middle cerebral arteries were occluded reduced significantly the size of the cerebral infarcts, compared to the control mice. These results suggest that N-SMase is a key component of the signaling pathways in cytokine- and other stress-induced cellular responses, and that inhibiting or stopping N-SMase activity is an important strategy to prevent neuron death from ischemia. 相似文献
63.
Nakayama K Kawato H Watanabe J Ohtsuka M Yoshida K Yokomizo Y Sakamoto A Kuru N Ohta T Hoshino K Yoshida K Ishida H Cho A Palme MH Zhang JZ Lee VJ Watkins WJ 《Bioorganic & medicinal chemistry letters》2004,14(2):475-479
The addition of substituents to the pyridopyrimidine scaffold of MexAB-OprM specific efflux pump inhibitors was explored. As predicted by a pharmacophore model, the incorporation substituents at the 2-position improved potency. Piperidines were found to be optimal, and further introduction of polar groups without compromising the activity was shown to be feasible. Careful positioning of the essential acidic moiety of the pharmacophore relative to the scaffold led to the discovery of vinyl tetrazoles with still greater potency. 相似文献
64.
DNA microarrays with unmodified oligonucleotides are a cost-effective alternative to cDNA microarrays. This study examined how purity, length, homology and GC content of the oligonucleotide probes influence the sensitivity and specificity of the method using cyanobacterial genes. Oligonucleotide purification by high pressure liquid chromatography was omitted without significant reduction in hybridization sensitivity. For two of three genes tested, a reduction in oligonucleotide length did not reduce hybridization sensitivity, and maximum sensitivity was achieved with probes that were 45 nt long. Oligonucleotide probes with 相似文献
65.
This paper reports chemical modification of silk sericin in LiCl/dimethyl sulfoxide (DMSO) solvent with 4-cyanophenyl isocyanate. Sericin is a highly hydrophilic protein secreted by Bombyx mori, serving as a protein glue in a cocoon. LiCl/DMSO was found to be a good solvent of sericin and useful for homogeneous modification of its abundant hydroxyl groups under nonaqueous condition. Fourier transform infrared (FTIR) analysis of the modified sericins revealed that 4-cyanophenyl groups were incorporated into sericin molecules mainly through urethane linkages. Several characteristics of the modified sericins such as solubility characteristic, hygroscopic property, and thermal stability were investigated. Secondary structure analysis using FTIR spectra suggested that formation of strong intermolecular hydrogen bonds was inhibited by the modification that is probably attributable to the incorporation of bulky 4-cyanophenyl groups. These results demonstrate that chemical modification of sericin using LiCl/DMSO solvent markedly alters its characteristics. 相似文献
66.
The synergistic effects of 6-alk(en)ylsalcylic acids, also known as anacardic acids, in combination with methicillin against Staphylococcus aureus ATCC 33591 (MRSA) was investigated. The double bond in C15-anacardic acids is not essential in eliciting the antibacterial activity but is associated with increasing the activity. The synergistic effects decreased with increasing the number of double bonds in the alkyl chain. On the other hand, the antibacterial activity of anacardic acids possessing different alkyl chain lengths against the same MRSA strain was found to be a parabolic function of their lipophilicity and maximized with the alkyl chain length of C10 and C12. Notably, the synergistic effects were noted to increase with increasing the alkyl chain length. 相似文献
67.
Izumi T Sakaguchi J Takeshita M Tawara H Kato K Dose H Tsujino T Watanabe Y Kato H 《Bioorganic & medicinal chemistry》2003,11(12):2541-2550
Structural modification of imiquimod (1), which is known as an interferon-alpha (IFN-alpha) inducer, for the aim of finding a novel and small-molecule tumor necrosis factor-alpha (TNF-alpha) suppressor and structure-activity relationship (SAR) are described. Structural modification of a imiquimod analogue, 4-amino-1-[2-(1-benzyl-4-piperidyl)ethyl-1H-imidazo[4,5-c]quinoline (2), which had moderate TNF-alpha suppressing activity without IFN-alpha inducing activity, led to a finding of 4-chloro-2-phenyl-1-[2-(4-piperidyl)ethyl]-1H-imidazo[4,5-c]quinoline (10) with potent TNF-alpha suppressing activity. The relation between conformational direction of 2-(4-piperidyl)ethyl group at position 1 and TNF-alpha suppressing activity is also demonstrated by NMR. 相似文献
68.
Deguchi Y Miyakawa Y Sakurada S Naito Y Morimoto K Ohtsuki S Hosoya K Terasaki T 《Journal of neurochemistry》2003,84(5):1154-1161
The purpose of this study was to clarify the mechanism of the blood-brain barrier (BBB) transport of H-Tyr-D-Arg-Phe-beta-Ala-OH (TAPA), which is a novel dermorphin analog with high affinity for the micro 1-opioid receptor. The in vivo BBB permeation influx rate of [125I]TAPA after an i.v. bolus injection (7.3 pmol/g body weight) into mice was estimated to be 0.265 +/- 0.025 microL/(min.g of brain). The influx rate of [125I]TAPA was reduced 70% by the coadministration of unlabeled TAPA (33 nmol/g of brain), suggesting the existence of a specific transport system for TAPA at the BBB. In order to elucidate the BBB transport mechanism of TAPA, a conditionally immortalized mouse brain capillary endothelial cell line (TM-BBB4) was used as an in vitro model of the BBB. The acid-resistant binding of [125I]TAPA, which represents the internalization of the peptide into cells, was temperature- and concentration-dependent with a half-saturation constant of 10.0 +/- 1.7 microm. The acid-resistant binding of TAPA was significantly inhibited by 2,4-dinitrophenol, dansylcadaverine (an endocytosis inhibitor) and poly-l-lysine and protamine (polycations). These results suggest that TAPA is transported through the BBB by adsorptive-mediated endocytosis, which is triggered by binding of the peptide to negatively charged sites on the surface of brain capillary endothelial cells. Blood-brain barrier transport via adsorptive-mediated endocytosis plays a key role in the expression of the potent opioid activity of TAPA in the CNS. 相似文献
69.
Umemura M Okamoto M Nakayama K Sagane K Tsukahara K Hata K Jigami Y 《The Journal of biological chemistry》2003,278(26):23639-23647
Glycosylphosphatidylinositol (GPI) is a conserved post-translational modification to anchor cell surface proteins to plasma membrane in all eukaryotes. In yeast, GPI mediates cross-linking of cell wall mannoproteins to beta1,6-glucan. We reported previously that the GWT1 gene product is a target of the novel anti-fungal compound, 1-[4-butylbenzyl]isoquinoline, that inhibits cell wall localization of GPI-anchored mannoproteins in Saccharomyces cerevisiae (Tsukahara, K., Hata, K., Sagane, K., Watanabe, N., Kuromitsu, J., Kai, J., Tsuchiya, M., Ohba, F., Jigami, Y., Yoshimatsu, K., and Nagasu, T. (2003) Mol. Microbiol. 48, 1029-1042). In the present study, to analyze the function of the Gwt1 protein, we isolated temperature-sensitive gwt1 mutants. The gwt1 cells were normal in transport of invertase and carboxypeptidase Y but were delayed in transport of GPI-anchored protein, Gas1p, and were defective in its maturation from the endoplasmic reticulum to the Golgi. The incorporation of inositol into GPI-anchored proteins was reduced in gwt1 mutant, indicating involvement of GWT1 in GPI biosynthesis. We analyzed the early steps of GPI biosynthesis in vitro by using membranes prepared from gwt1 and Deltagwt1 cells. The synthetic activity of GlcN-(acyl)PI from GlcN-PI was defective in these cells, whereas Deltagwt1 cells harboring GWT1 gene restored the activity, indicating that GWT1 is required for acylation of inositol during the GPI synthetic pathway. We further cloned GWT1 homologues in other yeasts, Cryptococcus neoformans and Schizosaccharomyces pombe, and confirmed that the specificity of acyl-CoA in inositol acylation, as reported in studies of endogenous membranes (Franzot, S. P., and Doering, T. L. (1999) Biochem. J. 340, 25-32), is due to the properties of Gwt1p itself and not to other membrane components. 相似文献
70.