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Sent on Sunday, 2011 Apr 17Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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| PubMed Results |
| 1. | Parasitol Res. 2011 Apr 15. [Epub ahead of print]Infection of retinal epithelial cells with L. amazonensis impacts in extracellular matrix proteins.da Silva Calabrese K, de Souza Silva L, Carvalho LO, de Jesus Hardoim D, da Silva-Almeida M, Mortara RA, da Silva Freitas de Souza C.Laboratório de Imunomodulação e Protozoologia, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil, 4635-Pavilhão 108, CEP 21040-900, Rio de Janeiro, RJ, Brazil, calabrese@ioc.fiocruz.br. AbstractOne of the manifestations of leishmaniases is eye injuries which main characteristics are the injury of the anterior chamber of the eye and the resistance to specific treatments. The retinal pigment epithelial (RPE) cells participate in pathogen-induced intraocular inflammatory processes. We investigated Leishmania amazonensis-RPE cells relationship and its impact in laminin and fibronectin production. Using RPE cell (ARPE-19), we demonstrated that L. amazonensis adhere to these cells in the first hour of infection, whereas parasite internalization was only observed after 6 h. Seventy-two hours after infection, vacuoles with parasites debris were observed intracellularly, and no parasite were observed intra- or extracellularly at the 96 h, suggesting that Leishmania can infect ARPE-19 cells although this cells are able to clear the infection. Fibronectin and laminin were associated with L. amazonensis-ARPE-19 interaction. Confocal analysis showed no substantial alterations in fibronectin presence in ARPE-19-infected or ARPE-19-noninfected cells, whereas laminin levels increased three times 10 h after L. amazonensis infection. After this time, laminin levels decreased in infected cells. These results suggest that L. amazonensis-ARPE-19 infection induces increased production of laminin in the beginning of infection which may facilitate parasite-host cell interactions. |
| PMID: 21494843 [PubMed - as supplied by publisher] | |
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| 2. | Med Mal Infect. 2011 Apr 12. [Epub ahead of print][Bilateral chronic and granulomatous total uveitis following cutaneous leishmaniasis.][Article in French] Bouomrani S, Farah A, Ayadi N, Béji M.Service de médecine interne, hôpital militaire de Gabes, 6000 Gabes, Tunisie. |
| PMID: 21493026 [PubMed - as supplied by publisher] | |
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| 3. | J Eur Acad Dermatol Venereol. 2011 Apr 15. doi: 10.1111/j.1468-3083.2011.04070.x. [Epub ahead of print]A pilot study comparing low-dose liposomal amphotericin B with N-methyl glucamine for the treatment of American cutaneous leishmaniasis.Motta J, Sampaio R.Hospital Universitário de Brasília (HUB) Universidade de Brasília (UnB), Brasilia-DF, Brazil. AbstractBackground Cutaneous leishmaniasis is an infectious re-emerging disease that has increased in incidence worldwide. Antimony, a highly toxic drug, remains the first choice therapy to treat it. Liposomal amphotericin B is active against Leishmania and is less toxic than antimony. Objective To compare low-dose liposomal amphotericin B with N-methyl glucamine for the treatment of American cutaneous leishmaniasis. Patients/Methods In a controlled open-label trial 35 patients with a localized form of American cutaneous leishmaniasis were included. They were allocated to a first group treated with 1.5 mg/kg/day of liposomal amphotericin B for 5 days, or to a second one treated with 20 mgSbV/kg/day of N-methyl glucamine for 20 days. Results In the first group, 50% and 81% of patients experienced a clinical cure and clinical improvement respectively. There was a 100% clinical cure in the second group. Conclusion Liposomal amphotericin B seems to be promising and safe for the treatment of American cutaneous leishmaniasis. © 2011 The Authors. Journal of the European Academy of Dermatology and Venereology © 2011 European Academy of Dermatology and Venereology. |
| PMID: 21492255 [PubMed - as supplied by publisher] | |
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| 4. | Org Biomol Chem. 2011 Mar 7;9(5):1653-60. Epub 2011 Jan 21.Probing the acceptor substrate binding site of T rypanosoma cruzi trans-sialidase with systematically modified substrates and glycoside libraries.Harrison JA, Kartha KP, Fournier EJ, Lowary TL, Malet C, Nilsson UJ, Hindsgaul O, Schenkman S, Naismith JH, Field RA.Centre for Biomolecular Sciences, University of St Andrews, St Andrews, UK KY16 9ST. AbstractSystematically modified octyl galactosides and octyl N-acetyllactosamines were assessed as inhibitors of, and substrates for, T. cruzi trans-sialidase (TcTS) in the context of exploring its acceptor substrate binding site. These studies show that TcTS, which catalyses the α-(2→3)-sialylation of non-reducing terminal β-galactose residues, is largely intolerant of substitution of the galactose 2 and 4 positions whereas substitution of the galactose 6 position is well tolerated. Further studies show that even the addition of a bulky sugar residue (glucose, galactose) does not impact negatively on TcTS binding and turnover, which highlights the potential of 'internal' 6-substituted galactose residues to serve as TcTS acceptor substrates. Results from screening a 93-membered thiogalactoside library highlight a number of structural features (notably imidazoles and indoles) that are worthy of further investigation in the context of TcTS inhibitor development. |
| PMID: 21253654 [PubMed - indexed for MEDLINE] | |
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| 5. | J Vector Ecol. 2010 Dec;35(2):385-94. doi: 10.1111/j.1948-7134.2010.00097.x.Ecology of Triatoma brasiliensis in northeastern Brazil: seasonal distribution, feeding resources, and Trypanosoma cruzi infection in a sylvatic population.Sarquis O, Carvalho-Costa FA, Oliveira LS, Duarte R, D Andrea PS, de Oliveira TG, Lima MM.Laboratório de Eco-Epidemiologia da Doença de Chagas, Instituto Oswaldo Cruz (IOC/Fiocruz), Rio de Janeiro, RJ, Brazil. AbstractWe assessed some ecological parameters of Triatoma brasiliensis in rock piles in the state of Ceará during the rainy and dry seasons. The greatest density was in April (median = 12.5 triatomines/site). The greatest abundance was in December, when the insects were more dispersed and the density per site was lower (6 triatomines/site). The nutritional status of females and 5th instar nymphs was increased in July. The rate of T. cruzi infection reached its highest peak in July (10.9%). ELISA revealed that the principal food sources were birds (33.1%), followed by armadillos (18.8%). Food sources were more frequently identified during the rainy season. T. brasiliensis specimens collected in the drought tended to: i) present lower rates of T. cruzi infection and gut content reactivity to tested antisera, ii) have a poorer nutritional status, iii) exhibit lower fecundity, iv) be more dispersed among the studied collection sites, and v) be more abundant and easily collected in the surface of the rocks, possibly reflecting an increased searching for blood meals. Such findings underscore epidemiological concerns and allow inferences about the season when triatomines can more frequently invade the peridomestic environment in search of food and recolonize artificial structures. © 2010 The Society for Vector Ecology. |
| PMID: 21175946 [PubMed - indexed for MEDLINE] | |
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| 6. | Biochemistry. 2011 Feb 8;50(5):836-42. Epub 2011 Jan 11.Proton transfer facilitated by ligand binding. An energetic analysis of the catalytic mechanism of Trypanosoma cruzi trans-sialidase.Pierdominici-Sottile G, Roitberg AE.Department of Chemistry and Quantum Theory Project, University of Florida, Gainesville, Florida 32611-8435, United States. AbstractTrans-sialidase is a crucial enzyme for the infection of Trypanosoma cruzi, the protozoa responsible for Chagas' disease in humans. This enzyme catalyzes the transfer of sialic acids from mammalian host cells to parasitic cell surfaces in order to mask the infection from the host's immune system. It represents a promising target for the development of therapeutics to treat the disease and has been subject of extensive structural studies. Elaborate experiments suggested formation of a long-lived covalent intermediate in the catalytic mechanism and identified a Tyr/Glu pair as an unusual catalytic couple. This requires that the tyrosine hydroxyl proton is transferred to the carboxylate group of glutamate before the nucleophilic attack. Since the solution pK(a)s of tyrosine and glutamate are very different, this transfer can only be accomplished if the reaction environment selectively stabilizes the product state. We compute the free energy profile for the proton transfer in different environments, and our results indicate that it can take place in the active site of trans-sialidase, but only after substrate binding. By means of the energy decomposition method, we explain the influence that the active site residues exert on the reaction and how the pattern is changed when the substrate is present. This study represents an initial step that can shed light on our understanding of the catalytic mechanism of this reaction. |
| PMID: 21162542 [PubMed - indexed for MEDLINE] | |
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| 7. | J Biomol Struct Dyn. 2011 Feb;28(4):455-69.Design of new chemotherapeutics against the deadly anthrax disease. Docking and molecular dynamics studies of inhibitors containing pyrrolidine and riboamidrazone rings on nucleoside hydrolase from Bacillus anthracis.Guimarães AP, Oliveira AA, da Cunha EF, Ramalho TC, França TC.Laboratory of Molecular Modeling Applied, Chemical and Biological Defense, Military Institute of Engineering, Praca General Tiburcio 80, 22290-270 Rio de Janeiro, Brazil. AbstractAnthrax is a disease caused by Bacillus anthracis, a dangerous biological warfare agent already used for both military and terrorist purposes. An important selective target for chemotherapy against this disease is nucleoside hydrolase (NH), an enzyme still not found in mammals. Having this in mind we have performed molecular docking studies, aiming to analyze the three-dimensional positioning of six known inhibitors of Trypanosoma vivax NH (TvNH) in the active site of B. anthracis NH (BaNH). We also analyzed the main interactions of these compounds with the active site residues of BaNH and the relevant factors to biological activity. These results, together with further molecular dynamics (MD) simulations, pointed out to the most promising compounds as lead for the design of potential inhibitors of BaNH. Most of the docking and MD results obtained corroborated to each other. Additionally, the docking results also suggested a good correlation with experimental data. |
| PMID: 21142217 [PubMed - indexed for MEDLINE] | |
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| 8. | Biochim Biophys Acta. 2011 Mar;1808(3):634-41. Epub 2010 Nov 30.Widefield microscopy for live imaging of lipid domains and membrane dynamics.Wheeler G, Tyler KM.BioMedical Research Centre, Norwich School of Medicine, University of East Anglia, Norwich NR47TJ, UK. AbstractWithin the lateral organisation of plasma membranes of polarized cell types there exist heterogeneous microdomains of distinct lipid composition, the small size of which (10-200 nm) makes them difficult to discern with traditional microscopic techniques, but which can be distinguished on the basis of lipid packing. These microdomains or rafts can be concentrated in larger more visible liquid-ordered regions, particularly by cross-linking of their constituents as in the immunological synapse or in features of the polarized cell such as pseudopodia or flagella. One technique, Laurdan fluorescence microscopy, has proven very useful for distinguishing such regions but has hitherto relied on 2-photon confocal microscopy. This has to some extent limited its utility to living systems and its widespread adoption in studying membrane dynamics on the surface of living cells. Here we describe and validate the adaptation of a standard widefield fluorescence microscope for live imaging of Laurdan stained cell membranes. Copyright © 2010 Elsevier B.V. All rights reserved. |
| PMID: 21126508 [PubMed - indexed for MEDLINE] | |
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| 9. | J Biol Chem. 2011 Feb 25;286(8):6627-40. Epub 2010 Nov 23.Intraphagosomal peroxynitrite as a macrophage-derived cytotoxin against internalized Trypanosoma cruzi: consequences for oxidative killing and role of microbial peroxiredoxins in infectivity.Alvarez MN , Peluffo G, Piacenza L, Radi R.Departamento de Bioquímica and Center for Free Radical and Biomedical Research, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay. AbstractMacrophage-derived radicals generated by the NADPH oxidase complex and inducible nitric-oxide synthase (iNOS) participate in cytotoxic mechanisms against microorganisms. Nitric oxide ((•)NO) plays a central role in the control of acute infection by Trypanosoma cruzi, the causative agent of Chagas disease, and we have proposed that much of its action relies on macrophage-derived peroxynitrite (ONOO(-) + ONOOH) formation, a strong oxidant arising from the reaction of (•)NO with superoxide radical (O(2)(-)). Herein, we have shown that internalization of T. cruzi trypomastigotes by macrophages triggers the assembly of the NADPH oxidase complex to yield O(2)(-) during a 60-90-min period. This does not interfere with IFN-γ-dependent iNOS induction and a sustained (•)NO production (∼24 h). The major mechanism for infection control via reactive species formation occurred when (•)NO and O(2)() were produced simultaneously, generating intraphagosomal peroxynitrite levels compatible with microbial killing. Moreover, biochemical and ultrastructural analysis confirmed cellular oxidative damage and morphological disruption in internalized parasites. Overexpression of cytosolic tryparedoxin peroxidase in T. cruzi neutralized macrophage-derived peroxynitrite-dependent cytotoxicity to parasites and favored the infection in an animal model. Collectively, the data provide, for the first time, direct support for the action of peroxynitrite as an intraphagosomal cytotoxin against pathogens and the premise that microbial peroxiredoxins facilitate infectivity via decomposition of macrophage-derived peroxynitrite. |
| PMID: 21098483 [PubMed - indexed for MEDLINE] | |
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