8 research outputs found
Estudio del mecanismo de activaciĂłn de la quinasa de proteĂnas dependiente de AMPc de Mucor Rouxii
Fil: Paveto, MarĂa Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Enzymatic and immunological detection of G protein α-subunits in the pathogenic fungus Candida albicans
Trypanosoma cruzi arginine kinase characterization and cloning. A novel energetic pathway in protozoan parasites
This work contains the first description of a guanidino kinase in a flagellar unicellular parasite. The enzyme phosphorylates L-arginine and was characterized in preparations from Trypanosoma cruzi, the ethiological agent of Chagas' disease. The activity requires ATP and a divalent cation. Under Standard assay conditions (1 mM L-arginine), the presence of 5-fold higher concentrations of canavanine or histidine produced a greater than 50% enzyme inhibition. The base sequence of this enzyme revealed an open reading frame of 357 amino acids and a molecular weight of 40,201. The amino acid sequence shows all of the characteristic consensus blocks of the ATP:guanidino phosphotransferase family and a putative 'actinin-type' actin-binding domain. The highest amino acid identities of the T. cruzi sequence, about 70%, were with arginine kinases from Arthropoda. Southern and chromosome blots revealed that the kinase is encoded by a single-copy gene. Moreover, Northern blot analysis showed an mRNA subpopulation of about 2.0 kilobases, and Western blotting of T. cruzi-soluble polypeptides revealed a 40-kDa band. The finding in the parasite of a phosphagen and its biosynthetic pathway, which are totally different from those in mammalian host tissues, points out this arginine kinase as a possible chemotherapy target for Chagas' disease.Fil: Pereira, Claudio Alejandro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Alonso, Guillermo Daniel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Paveto, Maria Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Iribarren, Adolfo Marcelo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Cabanas, MarĂa Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Torres, Hector Norberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Flawia, Mirtha Maria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentin
Anti-Trypanosoma cruzi Activity of Green Tea (Camellia sinensis) Catechins
The trypanocidal action of green tea catechins against two different developmental stages of Trypanosoma cruzi is reported for the first time. This activity was assayed with the nonproliferative bloodstream trypomastigote and with the intracellular replicative amastigote parasite forms. An ethyl acetate fraction from Camellia sinensis green tea leaves, which contains most of the polyphenolic compounds and the maximal trypanocidal activity, was obtained by fractionation of the aqueous extract with organic solvents. The active compounds present in this extract were further purified by LH-20 column chromatography and were identified by high-performance liquid chromatography analysis with a photo diode array detector and gas chromatography coupled to mass spectroscopy. The following flavan-3-ols derivatives, known as catechins, were identified: catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate. The purified compounds lysed more than 50% of the parasites present in the blood of infected BALB/c mice at concentrations as low as 0.12 to 85 pM. The most active compounds were gallocatechin gallate and epigallocatechin gallate, with minimal bactericidal concentrations that inhibited 50% of isolates tested of 0.12 and 0.53 pM, respectively. The number of amastigotes in infected Vero cells decreased by 50% in the presence of each of these compounds at 100 nM. The effects of the catechins on the recombinant T. cruzi arginine kinase, a key enzyme in the energy metabolism of the parasite, were assayed. The activity of this enzyme was inhibited by about 50% by nanomolar concentrations of catechin gallate or gallocatechin gallate, whereas the other members of the group were less effective. On the basis of these results, we suggest that these compounds could be used to sterilize blood and, eventually, as therapeutic agents for Chagas' disease
Immuno and Cytochemical Localization of Trypanosoma cruzi Nitric Oxide Synthase
The localization and subcellular disstribution of Trypasoma cruzi nitric oxide synthase was investigated in epimastigote cells by immunocytochemistry at electron and light microscope level, using a polyclonal antibody to neuronal nitric oxide synthase, and also, at light microscope level, by NADPH-daiphorase histochemical reaction. The immunoreactivity was ultrastructutrallu localized by EM in the inner surface of cell membranes and in free cytosolic clusters in the body, flagellum and apical extreme. Light microscopy showed that immunoprecipitates, specific for Trypanosoma cruzi nitric oxide synthase, co-localized with the formazan precipitates generated by the diaphorase reaction in the same areas identified by electron microscopy. These results, taken together with previous finfing from our laboratory could help to explain the involvement of the nitric oxide transduction pathway in T. cruzi epimastigote motility.Fil: Goldstein Raij, Jorge. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de BiologĂa Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de BiologĂa Celular y Neurociencia; ArgentinaFil: Paveto, Maria Cristina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: LĂłpez, Juan JosĂ©. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de BiologĂa Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de BiologĂa Celular y Neurociencia; ArgentinaFil: Pereira, Claudio Alejandro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Alonso, Guillermo Daniel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Torres, Hector Norberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Flawia, Mirtha Maria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentin
Retinal dysfunction in patients with chronic Chagasâdisease is associated to anti-Trypanosoma cruzi antibodies that crossreact with rhodopsin
To investigate retinal involvement in chronic Chagas' disease, we performed electroretinography and retinal fluorescein angiography studies in chagasic patients. Our results demonstrated a dissociated electrophysiological response characterized by both an abnormal reduction of the electroretinographic b-wave amplitude and a delayed latency, under the dark-adaptated condition. These alterations are compatible with a selective dysfunction of the rods. Antibodies raised against Trypanosoma cruzi that also interact with beta1-adrenergic receptor blocked light stimulation of cGMP-phosphodiesterase in bovine rod membranes. The specificity from the antibody-rhodopsin interaction was confirmed by Western blot analysis and antigenic competition experiments. Our results suggest an immunomediated rhodopsin blockade. T. cruzi infection probably induces an autoimmune response against rhodopsin in the chronic phase of Chagas' disease through a molecular mimicry mechanism similar to that described previously on cardiac human beta1-adrenergic and M2-cholinergic receptors, all related to the same subfamily of G-protein-coupled receptors.Fil: Matsumoto, Silvia C.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Labovsky, Vivian. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de BiologĂa y Medicina Experimental. FundaciĂłn de Instituto de BiologĂa y Medicina Experimental. Instituto de BiologĂa y Medicina Experimental; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Roncoroni, Marcela. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Guida, Maria Catalina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Gimenez, Luisa. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Mitelman, Jorge. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Gori, Horacio. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Jurgelevicius, Renata. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Grillo, Alejandro. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: Manfredi, Pablo. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Dr. Teodoro Ălvarez"; ArgentinaFil: LevĂŹn, Mariano J.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Paveto, Cristina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentin