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421.
Extracts of propolis samples collected in Brazil and Bulgaria were assayed against four Leishmania species--Leishmania amazonensis, L. braziliensis, L. chagasi from the New World, and L. major from the Old World--associated to different clinical forms of leishmaniasis. The composition of the extracts has been previously characterized by high temperature high resolution gas chromatography coupled to mass spectrometry. Considering the chemical differences among the extracts and the behavior of the parasites, it was observed significant differences in the leishmanicidal activities with IC50/1 day values in the range of 2.8 to 229.3 microg/ml . An overall analysis showed that for all the species evaluated, Bulgarian extracts were more active than the ethanol Brazilian extract. As the assayed propolis extracts have their chemical composition determined it merits further investigation the effect of individual components or their combinations on each Leishmania species. 相似文献
422.
Serrano SM Wang D Shannon JD Pinto AF Polanowska-Grabowska RK Fox JW 《The FEBS journal》2007,274(14):3611-3621
Snake venom metalloproteinases (SVMPs) have recently been shown to interact with proteins containing von Willebrand factor A (VWA) domains, including the extracellular matrix proteins collagen XII, collagen XIV, matrilins 1, 3 and 4, and von Willebrand factor (VWF) via their cysteine-rich domain. We extended those studies using surface plasmon resonance to investigate the interaction of SVMPs with VWF, and demonstrated that jararhagin, a PIII SVMP containing a metalloproteinase domain followed by disintegrin-like and cysteine-rich domains, catrocollastatin C, a disintegrin-like/cysteine-rich protein, and the recombinant cysteine-rich domain of atrolysin A (A/C) all interacted with immobilized VWF in a dose-dependent fashion. Binding of VWF in solution to immobilized A/C was inhibited by ristocetin and preincubation of platelets with A/C abolished ristocetin/VWF-induced platelet aggregation, indicating that the interaction of A/C with VWF is mediated by the VWA1 domain. Jararhagin cleaved VWF at sites adjacent to the VWA1 domain, whereas atrolysin C, a SVMP lacking the cysteine-rich domain, cleaved VWF at dispersed sites. A/C and catrocollastatin C completely inhibited the digestion of VWF by jararhagin, demonstrating that the specific interaction of jararhagin with VWF via the VWA1 domain is necessary for VWF proteolysis. In summary, we localized the binding site of PIII SVMPs in VWF to the A1 domain. This suggests additional mechanisms by which SVMPs may interfere with the adhesion of platelets at the site of envenoming. Thus, specific interaction of cysteine-rich domain-containing SVMPs with VWF may function to promote the hemorrhage caused by SVMP proteolysis of capillary basements and surrounding stromal extracellular matrix. 相似文献
423.
【目的】本研究旨在优化Grossowicz氧肟酸比色法测定粘虫Mythimna separata谷氨酰胺转胺酶(Ms TGase)活力的组合条件,以Ms TGase酶活力为依据分析其在不同龄期幼虫体内的分布规律。【方法】取4龄粘虫幼虫,通过组织匀浆和沉析纯化制备Ms TGase,采用Grossowicz比色法测定Ms TGase酶活力,并对Grossowicz比色法的多重实验因素进行正交优化,进一步结合差速离心法分析不同龄期幼虫体内和亚细胞组分(细胞核和细胞碎片,线粒体,微粒体以及胞质溶胶)中Ms TGase酶活力。【结果】结果表明,酶浓度、底物浓度、反应体系pH值、反应温度及钙离子浓度等实验因素都对Ms TGase酶活力测定结果产生显著影响,其影响大小顺序为:酶浓度>温度> p H>底物浓度>Ca2+浓度。Ms TGase酶比活力测定的最优化条件:酶浓度20 mg/m L、底物浓度0. 04 mol/L、反应体系pH值6. 5、测定温度37℃,不添加钙离子。在1-5龄幼虫中以4龄幼虫的Ms TGase酶活力最高,其比活力也显著高于其他龄期的,且在1-5龄幼虫胞质溶胶中Ms TGase酶活力分别占各亚细胞组分酶活力总和的39%,25%,48%,60%和61%。【结论】所获得的最优化条件适用于粘虫Ms TGase酶活力测定。Ms TGase在粘虫体内呈显著的龄期表达特征和亚细胞分布规律。 相似文献
424.
Flavoredoxin participates in Desulfovibrio gigas thiosulfate reduction pathway. Its 3-dimensional model was generated allowing the oxidized riboflavin-5'-phosphate (FMN) site to be predicted. Residues likely to be involved in FMN-binding were identified (N29, W35, T56, K92, H131 and F164) and mutated to alanine. Fluorescence titration with apoprotein showed that FMN is strongly bound in the wild-type protein. Comparison of K(d) values for mutants suggests that interactions with the phosphate group of FMN, contribute more to binding than the interactions with the isoalloxazine ring. The redox potential of bound FMN determined for wild-type and mutants revealed shifts to less negative values. These findings were correlated with the protein structure in order to contribute to a better understanding of the structure-function relationships in flavoredoxin. 相似文献
425.
Solange Vivier Aurélien Chepy Fabrice Bray Thomas Guerrier Silvia Speca Stéphanie Flament Manel Jendoubi Maïté Balden Christian Rolando Eric Hachulla David Launay Sylvain Dubucquoi Vincent Sobanski 《Proteomics》2022,22(3):2100116
Fibroblasts (Fb) are key effector cells in systemic sclerosis (SSc). Fb stimulation with transforming growth factor beta 1 (TGF-β1) is considered as a positive control in studies assessing fibrogenesis. The lack of standardization of TGF-β1 stimulation might be responsible for discrepancies in experiments performed in different conditions. Using quantitative proteomics analysis, we evaluated the impact of changes in experimental conditions on proteomic profiles of primary Fb. Principal component analysis (PCA) identified several groups of differentially expressed proteins influenced by cell passage, culture medium, and both concentration and duration of exposure to TGF-β1 stimulation. Bioinformatics analysis revealed that late passages expressed proteins involved in senescence. TGF-β1 concentration and time of stimulation were correlated with the expression of proteins involved in the fibrogenesis and inflammatory processes. These data underline the need for standardization of culture conditions to allow inter-data comparisons in future in vitro studies, especially when using “omics” approaches. 相似文献
426.
Nicolas Guex Isaac Crespo Sylvian Bron Assia Ifticene-Treboux Eveline Faes-van’t Hull Solange Kharoubi Robin Liechti Patricia Werffeli Mark Ibberson Francois Majo Mich?el Nicolas Julien Laurent Abhishek Garg Khalil Zaman Hans-Anton Lehr Brian J. Stevenson Curzio Rüegg George Coukos Jean-Fran?ois Delaloye Ioannis Xenarios Marie-Agnès Doucey 《PLoS computational biology》2015,11(3)
Angiogenesis plays a key role in tumor growth and cancer progression. TIE-2-expressing monocytes (TEM) have been reported to critically account for tumor vascularization and growth in mouse tumor experimental models, but the molecular basis of their pro-angiogenic activity are largely unknown. Moreover, differences in the pro-angiogenic activity between blood circulating and tumor infiltrated TEM in human patients has not been established to date, hindering the identification of specific targets for therapeutic intervention. In this work, we investigated these differences and the phenotypic reversal of breast tumor pro-angiogenic TEM to a weak pro-angiogenic phenotype by combining Boolean modelling and experimental approaches. Firstly, we show that in breast cancer patients the pro-angiogenic activity of TEM increased drastically from blood to tumor, suggesting that the tumor microenvironment shapes the highly pro-angiogenic phenotype of TEM. Secondly, we predicted in silico all minimal perturbations transitioning the highly pro-angiogenic phenotype of tumor TEM to the weak pro-angiogenic phenotype of blood TEM and vice versa. In silico predicted perturbations were validated experimentally using patient TEM. In addition, gene expression profiling of TEM transitioned to a weak pro-angiogenic phenotype confirmed that TEM are plastic cells and can be reverted to immunological potent monocytes. Finally, the relapse-free survival analysis showed a statistically significant difference between patients with tumors with high and low expression values for genes encoding transitioning proteins detected in silico and validated on patient TEM. In conclusion, the inferred TEM regulatory network accurately captured experimental TEM behavior and highlighted crosstalk between specific angiogenic and inflammatory signaling pathways of outstanding importance to control their pro-angiogenic activity. Results showed the successful in vitro reversion of such an activity by perturbation of in silico predicted target genes in tumor derived TEM, and indicated that targeting tumor TEM plasticity may constitute a novel valid therapeutic strategy in breast cancer. 相似文献
427.
Radovan Borojevic Alvaro N. A. Monteiro Solange A. Vinhas Gilberto B. Domont Paulo A. S. Mourão Hervé Emonard Gabriel Grimaldi Jr. Jean-Alexis Grimaud 《In vitro cellular & developmental biology. Plant》1985,21(7):382-390
Summary A continuous murine cell line (GRX) was obtained from fibrotic granulomas induced in C3H/HeN mice liver by experimental infection
withSchistosoma mansoni. This anchorage-dependent line produces composite connective tissue/extracellular matrix, displays morphological characteristics
of myofibroblasts, and can, under appropriate conditions, accumulate fat droplets. GRX cells produce viral particles of retrovirus
type. We consider GRX cell line to be representative of liver connective tissue cells, responsible for fibroplasia in liver
fibrotic and granulomatous reactions.
This research was supported by Centre National de la Recherche Scientifique, France; Financiadora de Estudos e Projetos (FINEP),
Brasil; and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Brasil. 相似文献
428.
In this paper, we present an original model of the atria, based on our hypothesis that atrial cells have features of pacemaker
cells, characterized by their normally longer intrinsic cycle lengths and different type of connection (stronger) than the,
sino-atrial (SA) node pacemaker cells. The atrium is simulated by a two-dimensional array of pacemaker cells (25 × 25), composed
of a region of SA node pacemaker cells (11 × 11) surrounded by atrial pacemaker cells. All pacemakers cells are characterized
by only the most relevant functional properties, those which play the most direct role in the determination of the cardiac
rate and in the mechanism of arrhythmias. These properties are: the intrinsic cycle length, τ, an `internal' feature of each
pacemaker cell, and the phase-response curve (PRC), an `overall collective' function. The PRC embodies the interactions of
each pacemaker cell with its neighboring cells, and thus represents the type of connection (strong, weak, etc.) of the pacemaker
cell with its surroundings. In our model, the SA node region differs from the atrial region by cycle length distribution and
PRCs. We studied the spatial interaction between SA node pacemaker cells and atrial pacemaker cells as a function of the regional
variation of cells properties and as a function of the “electrical” coupling between cells (the PRC), in the SA node region,
in the atrial region, and in a border zone between them. We investigated the influence of those parameters on the activation
pattern, on the conduction time of the array, and on a pseudo-ECG signal. This study demonstrates that by representing the
atrial cells as a population of `pacemaker-like' cells, similar to the SA node pacemaker cells, but differing markedly in
their cycle lengths and cell-to-cell interaction (PRC), we can create a global picture of the atrial system by applying a
simple physical-mathematical model. This approach enables us to explore physiological phenomena related to the genesis and
maintenance of atrial activity. It also reveals the conditions which predispose to atrial arrhythmias and conduction disturbances
(e.g. tachycardia, pacemaker shift, re-entry, fibrillation). In particular, it yields insight into the mechanism of transition
from normal atrial activity to the disordered state of atrial fibrillation. Therefore, this study suggests a new way of looking
at the development of cardiac arrhythmias of atrial origin.
Received: 8 September 1997 / Accepted in revised form: 6 October 1998 相似文献
429.
Gladys Len De Pinto Maritza Martínez Solange Ortega Neida Villavicencio Lisbeth Borjas 《Biochemical Systematics and Ecology》1993,21(8):795-797
Analytical data are presented for the polysaccharide of six gum specimens from Acacia tortuosa, a tropical American Gummiferae species. These data show that the gums were basically similar but differed in the sugar composition reported for most Acacia gum exudates studied so far. The presence of traces of xylose (<1%) and the absence of rhamnose in the gum specimens studied was very unusual. 相似文献
430.
Osvaldo A. Sant'Anna Solange Massa Denise Mouton Yolande Bouthillier Jean-Claude Mevel Olga M. Ibanez Ruth Vassao Marcelo de Franco Raquel Bellinati Maria Siqueira Guido Biozzi 《FEMS microbiology letters》1989,47(8-9):465-472
Abstract Susceptibility to Salmonella typhimurium infection was compared in H (high Ab responder) and L (low Ab responder) mice obtained by several selective breeding experiments (Selections I, II, III, IV and IV A) [10,19,22]. H mice were always much more susceptible to infection than their L mice counterparts within a continuous LD 50 variation range. In three of the selections (I, II and IV A) the low responsiveness character is known to result mainly from rapid Ag degradation in L mice macrophages. It was hypothesized that resistance to multiplication of intracellular pathogens could be related to an increased catabolic activity towards Ag. This was actually demonstrated, in F2 segregant hybrids of selection IV A, by the significant inverse correlation between capacity for Ab production and resistance to infection. 相似文献