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101.
Effect of antibiotics, levofloxacin and fosfomycin, on a mouse model with Escherichia coli O157 infection 总被引:6,自引:0,他引:6
Isogai E Isogai H Hayashi S Kubota T Kimura K Fujii N Ohtani T Sato K 《Microbiology and immunology》2000,44(2):89-95
There have been some reservations about the treatment of enterohemorrhagic Escherichia coli (EHEC) infection with antibiotics to prevent the occurrence of hemolytic uremic syndrome (HUS). However, the administration of antimicrobial agents for EHEC infection is under discussion. Therefore, we used an experimental mouse model to assess the advantage/disadvantage of two major antibiotics, levofloxacin (LVFX) and fosfomycin (FOM). Germ-free IQI mice were inoculated with EHEC O157 strain EDL931 or #7. Bacteria colonized feces at 10(9)-10(10) CFU/g, and Shiga toxins (STXs) were detected in the feces. From 1 day after infection, mice were assigned to LVFX (20 mg/kg) once daily or FOM (400 mg/kg) once daily. A significant decrease in overall mortality was observed after treatment of LVFX, with EHEC disappearing immediately from the feces of mice. FOM also reduced mortality for one strain, the STX level decreased gradually. LVFX exhibited higher therapeutic efficacy than FOM. Strain differences were observed in the model during the treatment. 相似文献
102.
This study used the human monocytic cell line U937 to examine whether or not Porphyromonas gingivalis fimbriae could induce the adhesion of monocytes to endothelial cells. An in vitro adhesion assay was used to investigate the effects of the fimbriae on U937 cell adhesion to human umbilical vein endothelial cells (HUVEC). The fimbriae enhanced U937 cell adhesion to HUVEC in a dose-dependent manner. U937 cells adhered better to HUVEC pretreated with the fimbriae for a minimum of 2 hr than to untreated HUVEC. The enhanced adhesion was inhibited by a monoclonal antibody against P. gingivalis 381 fimbriae. Pretreatment of U937 cells with the fimbriae for 24 hr enhanced U937 cell adhesion to HUVEC approximately 4-fold. This phenomenon was inhibited by an anti-CD11b antibody, suggesting the involvement of CD11b. These results indicate that P. gingivalis fimbriae can induce monocyte adhesion to the endothelial cell surface. They also suggest that the fimbriae may be involved in the initial event for infiltration of monocytes into the periodontal tissues of individuals with adult periodontitis. 相似文献
103.
Artificial sequences of the 153 amino acids have been designed to fit the main-chain framework of the sperm whale myoglobin (Mb) structure based on a knowledge-based 3D-1D compatibility method. The previously designed artificial globin (DG1) folded into a monomeric, compact, highly helical and globular form with overall dimensions similar to those of the target structure, but it lacked structural uniqueness at the side-chain level [Isogai, Y., Ota, M., Fujisawa, T. , Izuno, H., Mukai, M., Nakamura, H., Iizuka, T., and Nishikawa, K. (1999) Biochemistry 38, 7431-7443]. In this study, we redesigned hydrophobic sites of DG1 to improve the structural specificity. Several Leu and Met residues in DG1 were replaced with beta-branched amino acids, Ile and Val, referring to the 3D profile of DG1 to produce three redesigned globins, DG2-4. These residue replacements resulted in no significant changes of their compactness and alpha-helical contents in the absence of denaturant, whereas they significantly affected the dependence of the secondary structure on the concentration of guanidine hydrochloride. The analyses of the denaturation curves revealed higher global stabilities of the designed globins than that of natural apoMb. Among DG1-4, DG3, in which 11 Leu residues of DG1 are replaced with seven Ile and four Val residues, and one Met residue is replaced with Val, displayed the lowest stability but the most cooperative folding-unfolding transition and the most dispersed NMR spectrum with the smallest line width. The present results indicate that the replacements of Leu (Met) with the beta-branched amino acids at appropriate sites reduce the freedom of side-chain conformation and improve the structural specificity at the expense of stability. 相似文献
104.
Highly divergent sequences of the pollen self-incompatibility (S) gene in class-I S haplotypes of Brassica campestris (syn. rapa) L 总被引:1,自引:0,他引:1
Watanabe M Ito A Takada Y Ninomiya C Kakizaki T Takahata Y Hatakeyama K Hinata K Suzuki G Takasaki T Satta Y Shiba H Takayama S Isogai A 《FEBS letters》2000,473(2):139-144
Self-incompatibility (SI) enables flowering plants to discriminate between self- and non-self-pollen. In Brassica, SI is controlled by the highly polymorphic S locus. The recently identified male determinant, termed SP11 or SCR, is thought to be the ligand of S receptor kinase, the female determinant. To examine functional and evolutionary properties of SP11, we cloned 14 alleles from class-I S haplotypes of Brassica campestris and carried out sequence analyses. The sequences of mature SP11 proteins are highly divergent, except for the presence of conserved cysteines. The phylogenetic trees suggest possible co-evolution of the genes encoding the male and female determinants. 相似文献
105.
Molecular Characterization of Photomixotrophic Tobacco Cells
Resistant to Protoporphyrinogen
Oxidase-Inhibiting
Herbicides 总被引:2,自引:1,他引:1
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Naohide Watanabe Fang-Sik Che Megumi Iwano Seiji Takayama Takeshi Nakano Shigeo Yoshida Akira Isogai 《Plant physiology》1998,118(3):751-758
Peroxidizing herbicides inhibit protoporphyrinogen oxidase (Protox), the last enzyme of the common branch of the chlorophyll- and heme-synthesis pathways. There are two isoenzymes of Protox, one of which is located in the plastid and the other in the mitochondria. Sequence analysis of the cloned Protox cDNAs showed that the deduced amino acid sequences of plastidial and mitochondrial Protox in wild-type cells and in herbicide-resistant YZI-1S cells are the same. The level of plastidial Protox mRNA was the same in both wild-type and YZI-1S cells, whereas the level of mitochondrial Protox mRNA YZI-1S cells was up to 10 times the level of wild-type cells. Wild-type cells were observed by fluorescence microscopy to emit strong autofluorescence from chlorophyll. Only a weak fluorescence signal was observed from chlorophyll in YZI-1S cells grown in the Protox inhibitor N-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5,6-tetrahydrophthalimide. Staining with DiOC6 showed no visible difference in the number or strength of fluorescence between wild-type and YZI-1S mitochondria. Electron micrography of YZI-1S cells showed that, in contrast to wild-type cells, the chloroplasts of YZI-1S cells grown in the presence of N-(4-chloro-2-fluoro-5-propagyloxy)-phenyl-3,4,5,6-tetrahydrophthalimide exhibited no grana stacking. These results suggest that the herbicide resistance of YZI-1S cells is due to the overproduction of mitochondrial Protox. 相似文献
106.
107.
Role of UEV-1, an Inactive Variant of the E2 UbiquitinConjugating Enzymes, in In Vitro Differentiation and Cell Cycle Behavior of HT-29-M6 Intestinal Mucosecretory Cells 总被引:1,自引:0,他引:1
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108.
SHP-1 Binds and Negatively Modulates the c-Kit Receptor by Interaction with Tyrosine 569 in the c-Kit Juxtamembrane Domain 总被引:19,自引:0,他引:19
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Maya Kozlowski Louise Larose Fai Lee Duc Mingh Le Robert Rottapel Katherine A. Siminovitch 《Molecular and cellular biology》1998,18(4):2089-2099
The SH2 domain-containing SHP-1 tyrosine phosphatase has been shown to negatively regulate a broad spectrum of growth factor- and cytokine-driven mitogenic signaling pathways. Included among these is the cascade of intracellular events evoked by stem cell factor binding to c-Kit, a tyrosine kinase receptor which associates with and is dephosphorylated by SHP-1. Using a series of glutathione S-transferase (GST) fusion proteins containing either tyrosine-phosphorylated segments of the c-Kit cytosolic region or the SH2 domains of SHP-1, we have shown that SHP-1 interacts with c-Kit by binding selectively to the phosphorylated c-Kit juxtamembrane region and that the association of c-Kit with the larger of the two SHP-1 isoforms may be mediated through either the N-terminal or C-terminal SHP-1 SH2 domain. The results of binding assays with mutagenized GST-Kit juxtamembrane fusion proteins and competitive inhibition assays with phosphopeptides encompassing each c-Kit juxtamembrane region identified the tyrosine residue at position 569 as the major site for binding of SHP-1 to c-Kit and suggested that tyrosine 567 contributes to, but is not required for, this interaction. By analysis of Ba/F3 cells retrovirally transduced to express c-Kit receptors, phenylalanine substitution of c-Kit tyrosine residue 569 was shown to be associated with disruption of c-Kit–SHP-1 binding and induction of hyperproliferative responses to stem cell factor. Although phenylalanine substitution of c-Kit tyrosine residue 567 in the Ba/F3–c-Kit cells did not alter SHP-1 binding to c-Kit, the capacity of a second c-Kit-binding tyrosine phosphatase, SHP-2, to associate with c-Kit was markedly reduced, and the cells again showed hyperproliferative responses to stem cell factor. These data therefore identify SHP-1 binding to tyrosine 569 on c-Kit as an interaction pivotal to SHP-1 inhibitory effects on c-Kit signaling, but they indicate as well that cytosolic protein tyrosine phosphatases other than SHP-1 may also negatively regulate the coupling of c-Kit engagement to proliferation. 相似文献
109.
Xiaoyu Yu Dandan Zhang Bisheng Shi Guangxu Ren Xiuhua Peng Zhong Fang Maya Kozlowski Xiaohui Zhou Xiaonan Zhang Min Wu Cong Wang Zhenghong Yuan 《PloS one》2015,10(4)
Hepatitis B virus (HBV) persistent infection is associated with ineffective immune response for the clearance of virus. Immunomodulators represent an important class of therapeutics, which potentially could be beneficial for the treatment of HBV infection. The particulate yeast-derived glucan (PYDG) has been shown to enhance the innate and adaptive immune responses. We therefore, assessed the efficacy of PYDG in enhancing HBV specific immune responses by employing the hydrodynamic injection-based (HDI) HBV transfection mouse model. Mice were intragatric administered PYDG daily for 9 weeks post pAAV/HBV1.2 hydrodynamic injection. PYDG treatment significantly promoted HBV DNA clearance and production of HBsAb compared to control mice. PYDG treatment resulted in recruitment of macrophages, dendritic cells (DCs) and effector T cells to the liver microenvironment, accompanied by a significantly augmented DCs maturation and HBV-specific IFN-γ and TNF-α production by T cell. In addition, enhanced production of Th1 cytokines in liver tissue interstitial fluid (TIF) was associated with PYDG administration. Live imaging showed the accumulation of PYDG in the mouse liver. Our results demonstrate that PYDG treatment significantly enhances HBV-specific Th1 immune responses, accompanied by clearance of HBV DNA, and therefore holds promise for further development of therapeutics against chronic hepatitis B. 相似文献
110.
Kate Buchacz Miao-Jung Chen Maree Kay Parisi Maya Yoshida-Cervantes Erin Antunez Viva Delgado Nicholas J. Moss Susan Scheer 《PloS one》2015,10(3)