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kinetics of the intracellular differentiation of leishmania amazonensis and internalization of host mhc molecules by the intermediate parasite stages.the establishment of leishmania in mammals depends on the transformation of metacyclic promastigotes into amastigotes within macrophages. the kinetics of this process was examined using mouse macrophages infected with metacyclic promastigotes of l. amazonensis. the appearance of amastigote characteristics, including large lysosome-like organelles called megasomes, stage-specific antigens, high cysteine protease activity and sensitivity to l-leucine methyl ester, was followed over a 5-day period. ...200111289063
invasive forms of toxoplasma gondii, leishmania amazonensis and trypanosoma cruzi have a positive charge at their contact site with host cells.we examined the surface charges of invasive forms of toxoplasma gondii, leishmania amazonensis, and trypanosoma cruzi by atomic force microscopy and surface potential spectroscopy. we found that the specific part of the protozoan which makes initial contact with the host cell is positively charged. this indicates that the positive charge at the site of contact facilitates binding of the invasive protozoan to negatively charged host cells.200111293566
antileishmanial activity of an indole alkaloid from peschiera australis.in this study, we show the leishmanicidal effects of a chloroform fraction (clf) and a purified indole alkaloid obtained from crude stem extract of peschiera australis against leishmania amazonensis, a causative agent of cutaneous leishmaniasis in the new world. in a bioassay-guided chemical fractionation, the leishmanicidal activity in clf completely and irreversibly inhibited promastigote growth. this fraction was also active against amastigotes in infected murine macrophages. chemical analysi ...200111302794
application of flow cytometry and microscopical methods to characterize the effect of herbal drugs on leishmania spp.the world health organization has identified leishmania sis as a major public health problem, particularly in africa, asia, and latin america. about 1.5 to 2 million people are affected annually by this parasitic infection. as there is no vaccine, there is still a strong need for sufficient drugs. in a preliminary screening, extracts of 50 different plants were evaluated for their possible leishmanicidal activity against the promastigote form of leishmania mexicana amazonensis. eighteen extracts ...200111312576
in vitro growth of leishmania amazonensis promastigotes resistant to pentamidine is dependent on interactions among strains.the in vitro growth of promastigote cells of leishmania amazonensis was found to strongly depend on interactions among strains that differed in their pentamidine resistance. in particular, the growth of resistant strains was reduced when they shared the same environment with a less-resistant strain.200111353656
role of peroxynitrite in macrophage microbicidal mechanisms in vivo revealed by protein nitration and hydroxylation.the cytotoxins produced by phagocytic cells lacking peroxidases such as macrophages remain elusive. to elucidate macrophage microbicidal mechanisms in vivo, we compared the lesion tissue responses of resistant (c57bl/6) and susceptible (balb/c) mice to leishmania amazonensis infection. this comparison demonstrated that parasite control relied on lesion macrophage activation with inducible nitric oxide synthase expression (inos), nitric oxide synthesis, and extensive nitration of parasites inside ...200111368921
pre-exposure with low-dose uva suppresses lesion development and enhances th1 response in balb/c mice infected with leishmania (leishmania) amazonensis.this study was conducted to determine whether exposing mice to ultraviolet (uv) radiation would alter the pathogenesis of infection with leishmania (leishmania) amazonensis (l. amazonensis) which causes progressive cutaneous disease in susceptible mouse strains. balb/c mice were irradiated with 10 and 30 j/cm(2) uva on shaved skin of the back from dermaray (m-dmr-100) for 4 consecutive days before infection with leishmania promastigotes. the course of disease was recorded by measuring the size o ...200111390207
a mg-dependent ecto-atpase in leishmania amazonensis and its possible role in adenosine acquisition and virulence.the plasma membrane of cells contains enzymes whose active sites face the external medium rather than the cytoplasm. the activities of these enzymes, referred to as ectoenzymes, can be measured using living cells. in this work we describe the ability of living promastigotes of leishmania amazonensis to hydrolyze extracellular atp. in these intact parasites whose viability was assessed before and after the reactions by motility and by trypan blue dye exclusion, there was a low level of atp hydrol ...200111414680
enhanced activity of antisense phosphorothioate oligos against leishmania amastigotes: augmented uptake of oligo, ribonuclease h activation, and efficient target intervention under altered growth conditions.leishmania, a parasitic protozoan, infects human macrophages, often causing severe morbidity and mortality. the pathogenic form of this parasite, the amastigote, lives inside the acidic phagolysosomes of infected macrophages. in our attempt to develop anti-miniexon phosphorothioate oligodeoxyribonucleotides (s-oligos) as an alternative chemotherapy against leishmania, we found that intracellular as well as 'axenic' amastigotes were more susceptible to these s-oligos than were the cultured promas ...200111585054
leishmania amazonensis-dendritic cell interactions in vitro and the priming of parasite-specific cd4(+) t cells in vivo.the progressive disease following leishmania amazonensis infection in mice requires functional cd4(+) t cells, which are primed to a disease-promoting phenotype during the infection. to understand how these pathogenic t cells are generated and the role of dendritic cells (dcs) in this process, we use dcs of susceptible balb/c and resistant c3h/hej mice to examine parasite-dc interactions in vitro as well as the effector phenotype of t cells primed by parasite-exposed dcs in vivo. our results dem ...200111591781
inhibition of macrophage invasion by monoclonal antibodies specific to leishmania (viannia) braziliensis promastigotes and characterisation of their antigens.monoclonal antibodies that specifically recognise leishmania (viannia) braziliensis promastigotes were produced and termed sst-2, sst-3 and sst-4. sst-2 recognises a conformational epitope present in a 24-28 kda doublet and in a 72 kda component, as verified by western blotting. indirect immunofluorescence showed that the antigen recognised by sst-2 is distributed homogeneously on the parasite surface. sst-3 recognises a flagellar glycoprotein of approximately 180 kda. the reactivity of this mab ...200111595232
a randomized double-blind placebo-controlled trial to evaluate the immunogenicity of a candidate vaccine against american tegumentary leishmaniasis.this study was aimed at evaluating the immunogenicity of a vaccine composed of killed leishmania amazonensis promastigotes using several different protocols in a randomized, double-blind and controlled trial design in order to select one of them for further efficacy trials. one hundred and fourteen leishmanin skin test (lst)-negative healthy volunteers were allocated into eight groups that received either two or three deep intramuscular injections of vaccine at doses of 180, 360 and 540 microg o ...200111700183
differences in gamma interferon production in vitro predict the pace of the in vivo response to leishmania amazonensis in healthy volunteers.the initial encounter of leishmania cells and cells from the immune system is fundamentally important in the outcome of infection and determines disease development or resistance. we evaluated the anti-leishmania amazonensis response of naive volunteers by using an in vitro priming (ivp) system and comparing the responses following in vivo vaccination against the same parasite. in vitro stimulation allowed us to distinguish two groups of individuals, those who produced small amounts of gamma int ...200111705920
attempt to differentiate leishmania (leishmania) amazonensis, l. (l.) chagasi, leishmania (viannia) braziliensis and l. (v.) guyanensis using the ssr-pcr technique.the ability to differentiate reference strains of leishmania (leishmania) amazonensis, l. (l.) chagasi, leishmania (viannia) braziliensis and l. (v.) guyanensis was evaluated using the simple sequence repeat polymerase chain reaction (ssr-pcr) technique. this technique differentiates the leishmania species, generating distinct dna amplicon profiles. the ssr-pcr profiles were similar to but more reproducible than those produced by rapd. ssr-pcr is presented as an alternative to other molecular me ...200111763439
protein kinase a of leishmania amazonensis as a potential target for methoxy-amidine.cyclic 3',5'-adenosine monophosphate (camp) is one of the most important signaling molecules for cell growth and differentiation in several systems including protozoal parasites such as trypanosoma cruzi and leishmania species. the most important event during leishmania developmental cycle is the differentiation of procyclic into metacyclic promastigotes, which is associated with the appearance of pathogenicity. as previously demonstrated leishmania amazonensis metacyclogenesis is associated wit ...200111765595
homologues of lmpk, a mitogen-activated protein kinase from leishmania mexicana, in different leishmania species.lmpk, a mitogen-activated protein (map) kinase homologue of leishmania mexicana, is essential for the proliferation of the amastigote, the mammalian stage of the protozoan parasite. this has been demonstrated using deletion mutant promastigotes, the insect stage of the parasite: first, in vitro after differentiation to amastigotes, which subsequently lost their potential to proliferate; second, by infection of peritoneal macrophages, which were able to cope with the infection and cleared the par ...200111770102
[building of a genomic library of leishmania amazonensis and its expression in balb/c mice's muscle].a genomic library of leishaminia amazonensis was built through a pcdna3 vector, with expression promoter in eukaryot cells, to contribute to the application of immunization technology with nucleic acids in leishmaniasis. to show the expression genomic library in the muscles of mice immunized with it, the indirect immunofluoresce technique was used. a mix of sera with high antileishmania titers from an area where l.braziliensis infection is predominant was used as primary antibody. a library of 8 ...200115846918
extracellular release of the glycosylphosphatidylinositol (gpi)-linked leishmania surface metalloprotease, gp63, is independent of gpi phospholipolysis: implications for parasite virulence.the major zinc metalloprotease of leishmania (gp63), an important determinant of parasite virulence, is attached to the parasite surface via a glycosylphosphatidylinositol anchor. here we report the spontaneous release of proteolytically active gp63 from a number of leishmania isolates, causing cutaneous and visceral disease. to investigate the mechanism(s) of gp63 release, we transfected a gp63-deficient variant of leishmania amazonensis with constructs expressing gp63 and various mutants there ...200211777912
ultrastructural and biochemical alterations induced by 22,26-azasterol, a delta(24(25))-sterol methyltransferase inhibitor, on promastigote and amastigote forms of leishmania amazonensis.we report on the antiproliferative effects and the ultrastructural and biochemical alterations induced in vitro by 22,26-azasterol, a sterol delta(24(25))-methyltransferase (24-smt) inhibitor, on leishmania amazonensis. when promastigotes and amastigotes were exposed to 100 nm 22,26-azasterol, complete growth arrest and cell lysis ensued after 72 (promastigotes) or 120 (amastigotes) h. exposure of parasites to this azasterol led to the complete depletion of parasite endogenous sterols (episterol ...200211796362
a plasma membrane p-type h(+)-atpase regulates intracellular ph in leishmania mexicana amazonensis.a recent report (mukherjee et al., j. biol. chem. 276 (2001) 5563) has proposed that the plasma membrane mg(+)-atpase of promastigotes of leishmania donovani, that is involved in its intracellular ph regulation, is an electroneutral h(+)/k(+) antiporter rather than an electrogenic h(+) pump. since this proposition has important implications for the use of the pump as a target for chemotherapy, we investigated its nature in the mammalian stage (amastigote) of l. mexicana amazonensis and compared ...200211814574
characterization and cytochemical localization of an atp diphosphohydrolase from leishmania amazonensis promastigotes.an atp diphosphohydrolase was identified in the plasma membranes isolated from promastigote forms of leishmania amazonensis. both atp and adp were hydrolysed at similar rates by the enzyme. other nucleotides such as utp, gtp and ctp were also degraded, revealing a broad substrate specificity. adding atp and adp simultaneously, the amount of hydrolysis achieved was compatible with the presence of a single enzyme. atpase activity was not affected by addition of vanadate, ouabain, thapsigargin, dic ...200211862992
synthetic derivatives of curcumin and their activity against leishmania amazonensis.in a previous work, the in vitro and in vivo activity of a series of diarylheptanoid derivatives against leishmania amazonensis has been described. based on the promising results, ten new compounds belonging to the same chemical class were synthesized and have been investigated in relation to their leishmanicidal activity. the compounds were obtained through several chemical modifications on the basic structure of curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) in an atte ...200211878200
in vitro activities of iboga alkaloid congeners coronaridine and 18-methoxycoronaridine against leishmania amazonensis.in previous studies, we demonstrated the leishmanicide effect of coronaridine, a natural indole alkaloid isolated from stem bark of peschiera australis (delorenzi et al., antimicrob. agents chemother. 45:1349-1354, 2001). in this study we show the leishmanicidal effect of the synthetic coronaridine and its racemic 18-methoxylated analog, 18-methoxycoronaridine. both alkaloids revealed a potent leishmanicide effect against leishmania amazonensis, a causative agent of cutaneous and diffuse cutaneo ...200212069962
synthesis, and biological evaluation of new 1,3,4-thiadiazolium-2-phenylamine derivatives against leishmania amazonensis promastigotes and amastigotes.1,3,4-thiadiazolium-2-aminide, which is a class of mesoionic compounds, were tested against promastigote and amastigote forms of leishmania amazonensis. parasites were assayed with or without the drugs in axenic media, using pentamidine isethionate as a reference drug. the very promising results showed us the most active compounds were the 4'- and 3'-methoxy derivatives against promastigote forms, while the highest activity against the amastigote forms was obtained with the 4'-fluor and 3'-bromo ...200212660023
cloning and characterization of a leucyl aminopeptidase from three pathogenic leishmania species.aminopeptidases are emerging as exciting novel drug targets and vaccine candidates in parasitic infections. in this study, we describe for the first time an aminopeptidase from three highly pathogenic leishmania species. intronless genes encoding a leucyl aminopeptidase (lap) were cloned from leishmania amazonensis, leishmania donovani, and leishmania major, which encoded 60-kda proteins that displayed homology to leucyl aminopeptidases from gram-negative bacteria, plants, and mammals. the lap g ...200212006595
influence of vertebrate blood meals on the development of leishmania (viannia) braziliensis and leishmania (leishmania) amazonensis in the sand fly lutzomyia migonei (diptera: psychodidae).the effect of blood meals from humans and seven domestic, wild, or laboratory animals (dogs, horses, chickens, rats, opossums, mice, and hamsters) on the development of leishmania braziliensis and l. amazonensis was studied in the sand fly lutzomyia migonei. the development of l. braziliensis and l. amazonensis exhibited peripylarian and suprapylarian patterns of development, respectively, in the sand fly gut with all blood meals tested. the blood meal sources influenced the infection rate of th ...200212518856
the expression system of biologically active canine interleukin-8 in leishmania promastigotes.it has been reported that leishmania promastigotes have ability to express foreign genes on drug selectable plasmids. to investigate further abilities of the recently described expression vector, p6.5, in the transfection of leishmania organisms (chen d-q, kolli bk, yadava n et al. episomal expression of specific sense and antisense mrnas in leishmania amazonensis: modulation of gp63 levels in promastigotes and their infection of macrophages in vitro. infect immun 2000;68:80--86), the constructe ...200211880228
early enhanced th1 response after leishmania amazonensis infection of c57bl/6 interleukin-10-deficient mice does not lead to resolution of infection.c3h and c57bl/6 mice are resistant to leishmania major but develop chronic lesions with persistent parasite loads when they are infected with leishmania amazonensis. these lesions develop in the absence of interleukin-4 (il-4), indicating that susceptibility to this parasite is not a result of development of a th2 response. expression of the cytokine il-10 during infection could account for the lack of il-12 expression and poor cell-mediated immunity towards the parasite. therefore, we tested th ...200211895981
overexpression of the leishmania amazonensis ca2+-atpase gene lmaa1 enhances virulence.a gene for a ca2+-transporting atpase (lmaa1) from the trypanosomatid parasite leishmania (mexicana) amazonensis was overexpressed in two clones of l. amazonensis differing in their virulence. rna and protein expression of the gene was increased in transfectants, as was the infectivity of transfectants versus parental types in both mouse and in vitro macrophage infection experiments. the virulence of the almost avirulent clone was enhanced such that it was more virulent than the parental 'virule ...200211896767
risk factors associated with asymptomatic infection by leishmania chagasi in north-east brazil.various factors have been associated with a predisposition to the development of clinical american visceral leishmaniasis (avl). however, little information is available about the factors that predispose to asymptomatic infection. to identify the risk factors associated with asymptomatic infection, a study was carried out between july 1997 and june 1998 on children aged 0-5 years in the districts of vila nova and bom viver in the municipality of raposa in the island of são luís, state of maranhã ...200211925984
immunochemotherapy for cutaneous leishmaniasis: a controlled trial using killed leishmania (leishmania) amazonensis vaccine plus antimonial.leishmaniasis is endemic in 88 countries in the world, and 350 million individuals are at risk of acquiring the disease. treatment for american cutaneous leishmaniasis (acl) is long, expensive, and associated with important side-effects.200211982640
low-dose uvb contributes to host resistance against leishmania amazonensis infection in mice through induction of gamma interferon and tumor necrosis factor alpha cytokines.uv radiation suppresses the immune response, a fact which raises the question of whether the phenomenon may find practical applications in the outcome of infectious diseases. in this study, balb/c mice were exposed to low-dose uvb (250 j/m(2)) from dermaray m-dmr-100 for 4 consecutive days. twelve hours after the last uv exposure, groups of mice were injected with 2 x 10(6) leishmania amazonensis promastigotes. the development of skin lesions, as assessed by measurement of visible cutaneous lesi ...200211986277
expression and processing of megasome cysteine proteinases during leishmania amazonensis differentiation.amastigotes of leishmania species belonging to the leishmania mexicana complex exhibit large lysosomes, called megasomes, which are rich in cysteine proteinases. various aspects of the host-parasite interaction, the differentiation process as well as intracellular survival, have been attributed to these proteinases. the in vitro differentiation from promastigote to amastigote forms of leishmania amazonensis was evaluated using the analysis of the expression of cysteine proteinase (lpcys2) by nor ...200211999020
co-infection by leishmania amazonensis and l. infantum/l. chagasi in a case of diffuse cutaneous leishmaniasis in bolivia.we present the first report of a co-infection by leishmania amazonensis and l. infantum/l. chagasi isolated in 1993 from a patient with diffuse cutaneous leishmaniasis (dcl), living in the sub-andean region of bolivia. this is the third reported case of dcl in bolivia, but the first one with isoenzymatic identification of the aetiological agents involved and the first one giving evidence for a mixed infection by 2 leishmania parasites in the same lesion.200212474481
leishmanicidal activity of two canthin-6-one alkaloids, two major constituents of zanthoxylum chiloperone var. angustifolium.the crude alkaloidal extract of zanthoxylum chiloperone stem bark exhibited in vitro activity against various strains of leishmania ssp. at 100 microg/ml. two active major constituents were isolated and identified as canthin-6-one and 5-methoxycanthin-6-one. the effect of these compounds was also tested in an in vivo assay using balb/c mice infected with leishmania amazonensis. the mice were treated for 5 weeks postinfection with these alkaloids by oral (14 days) or intralesional route (4 days) ...200212007711
vaccination of c57bl/10 mice against cutaneous leishmaniasis using killed promastigotes of different strains and species of leishmania.antigenic extracts from five leishmania stocks were used to vaccinate c57bl/10 mice. the leishvacin(r) and ph8 monovalent vaccine yielded the highest ifn-gamma levels in the supernatants of spleen cell culture from vaccinated animals. each single strain immunized group showed evidence of protective immunity six months after the challenge with promastigotes of leishmania (leishmania) amazonensis. no differences were detected between the vaccinated groups. it can be concluded that vaccines compose ...200212011920
technetium-99m labeling anti-amastigote polyclonal antibodies of leishmania amazonensis.anti-amastigote polyclonal antibody (igg) was incubated with solutions of stannous chloride and sodium borohidride. after that, 3.7 mbq of technetium-99m (99mtc) was added. a labeling yield of the antibody about 84% was obtained. after filtration of 99mtc-igg, the radiochemical purity increased from 84 to 95%. the labeling of igg with 99mtc did not modify the immunoreactivity of the antibody, since it was able to identify in vitro and in vivo the specific antigen of leishmania amazonensis.200212031875
molecular modeling approaches for determining gene function: application to a putative poly-a binding protein from leishmania amazonensis (lapabp).the great expansion in the number of genome sequencing projects has revealed the importance of computational methods to speed up the characterization of unknown genes. these studies have been improved by the use of three dimensional information from the predicted proteins generated by molecular modeling techniques. in this work, we disclose the structure-function relationship of a gene product from leishmania amazonensis by applying molecular modeling and bioinformatics techniques. the analyzed ...200212048561
genetic variation in populations of leishmania species in brazil.the population structure of strains of leishmania (viannia) braziliensis sensu lato from pará state and paraná state in brazil, of l. (v.) shawi and l. (leishmania) amazonensis from pará state, and the relationships of type strains of the subgenera l. (viannia) and l. (leishmania) were examined by the random-amplified polymorphic deoxyribonucleic acid (rapd) technique. four different primers (m13-40, qg1, l15996 and delta gt11r) were used. the bands were analysed using the neighbor-joining (nj) ...200212055823
genomic organisation and transcription characterisation of the gene encoding leishmania (leishmania) amazonensis arginase and its protein structure prediction.the genomic organisation of the gene encoding leishmania (leishmania) amazonensis arginase as well as its flanking regions were characterised. the size of the transcribed rna was determined, allowing us to map the genomic sites signalling for rna trans-splicing and putative polyadenylation regions. the general organisation was compared with genes encoding other proteins already described in organisms of the trypanosomatid family. the complete nucleotide sequence of the arginase open reading fram ...200212062491
nitric oxide-mediated proteasome-dependent oligonucleosomal dna fragmentation in leishmania amazonensis amastigotes.resistance to leishmanial infections depends on intracellular parasite killing by activated host macrophages through the l-arginine-nitric oxide (no) metabolic pathway. here we investigate the cell death process induced by no for the intracellular protozoan leishmania amazonensis. exposure of amastigotes to moderate concentrations of no-donating compounds (acidified sodium nitrite nano(2) or nitrosylated albumin) or to endogenous no produced by lipopolysaccharide or gamma interferon treatment of ...200212065515
opsonization modulates rac-1 activation during cell entry by leishmania amazonensis.lesions caused by leishmania amazonensis normally heal, but relapses occur due to parasite persistence in host tissues. it has been proposed that infection of fibroblasts plays an important role in this process by providing the parasites with a safe haven in which to replicate. however, most previous studies have focused on the entry of leishmania into macrophages, a process mediated by serum opsonins. to gain insight into a possible role of nonopsonic entry in the intracellular persistence of a ...200212117970
evaluation of antigens from various leishmania species in a western blot for diagnosis of american tegumentary leishmaniasis.a western blot method that uses antigens from culture promastigote forms of leishmania (viannia) braziliensis, l. (leishmania) amazonensis, l. (leishmania) tropica, and a trypanosomatid (strain 268t) isolated from naturally infected tomatoes was evaluated for laboratory diagnosis of american tegumentary leishmaniasis (atl). serum samples were obtained from 108 patients with atl (group i), 23 chagasic patients (group ii), 32 patients with other diseases (group iii), and 78 healthy individuals (gr ...200212135276
succinate secreted by trypanosoma brucei is produced by a novel and unique glycosomal enzyme, nadh-dependent fumarate reductase.in all trypanosomatids, including trypanosoma brucei, glycolysis takes place in peroxisome-like organelles called glycosomes. these are closed compartments wherein the energy and redox (nad(+)/nadh) balances need to be maintained. we have characterized a t. brucei gene called frdg encoding a protein 35% identical to saccharomyces cerevisiae fumarate reductases. microsequencing of frdg purified from glycosome preparations, immunofluorescence, and western blot analyses clearly identified this enzy ...200212138089
analysis of t helper cell responses during infection with leishmania amazonensis.most inbred strains of mice are susceptible to leishmania amazonensis infection and develop progressive cutaneous lesions. however, the role of th subsets in the disease and the molecular basis of pathogenesis are unclear. to address this issue, we examined the frequency of cytokine-producing cd4+ t cells and the profile of alphabeta t cell receptor (tcr) usage in infected balb/c mice. at different infection stages, cd4+ cells of draining lymph nodes contained comparable frequencies of th1 and t ...200212164286
polymorphism analysis of the internal transcribed spacer and small subunit of ribosomal rna genes of leishmania mexicana.leishmania mexicana causes a wide spectrum of clinical diseases. in spite of the variety of clinical forms, no data exist regarding genetic polymorphism of l. mexicana. we analyzed the polymorphism of the internal transcribed spacer (its) and the small subunit rrna genes of 3 reference strains and 24 mexican isolates of l. mexicana, by means of polymerase chain reaction and subsequent digestion by restriction enzymes. all strains of l. mexicana had invariant patterns for both the its and the sma ...200212209333
pretreatment of leishmania homologue of receptors for activated c kinase (lack) promotes disease progression caused by leishmania amazonensis.a cdna coding leishmania homologue of receptors for activated c kinase (lack), which was known to play an important role in the early phase of leishmania infection, was molecularly cloned from leishmania amazonensis promastigote by using reverse transcription and nested polymerase chain reaction, and was sequenced. the l. amazonenis lack cdna showed 97.3 to 99.3% homology and its deduced amino acid sequence showed 98.7 to 99.7% identity in comparison with lack sequences from five other species. ...200212221926
paracoccidioides brasiliensis-reactive antibodies in brazilian blood donors.in a survey for primary paracoccidioidomycosis (pcm) infection (and not the clinical disease), two groups of blood donors were analyzed. one study group was drawn from donors living in a rural area where pcm is endemic, and the other group from urban residents of a large city, são paulo. anti-paracoccidioides brasiliensis (pb) specific antibodies (igg) in sera were analyzed by elisa, using crude pb exoantigens (exoag) and purified specific pb 43 kda glycoprotein (gp43). the results showed that 2 ...200212230218
studies on quinones. part 37. synthesis and biological activity of o-aminoester functionalised benzo- and naphtho[2,3-b]thiophenequinones.the synthesis of 3-amino-2-methoxycarbonyl-4,7-dimethoxybenzo[b]thiophene (5) and benzothieno[3,2-d][1,3]oxazin 15 from 3,6-dimethoxy-2-nitrobenzaldehyde (1) is reported. benzo[b]thiophene-4,7-quinones 9 and 10 were prepared in good yields by oxidative deprotection of the corresponding dimethoxybenzothiophenes 8 and 7. cycloaddition reaction of quinone 8 with 1-(e)-trimethylsilyloxy-1,3-butadiene followed by acid-induced aromatization provides access to naphtho[2,3-b]thiophene-4,9-quinone 13 and ...200212237538
a simple and reproducible method to obtain large numbers of axenic amastigotes of different leishmania species.this work describes a simple method to yield large amounts of leishmania amastigote-like forms in axenic cultures using promastigotes as the starting population. the method described induced extracellular amastigote transformation of leishmania amazonensis (97%), leishmania braziliensis (98%) and leishmania chagasi (90%). the rounded parasites obtained in axenic cultures were morphologically similar, even at the ultrastructural level, to intracellular amastigotes. moreover, the axenic amastigote ...200212375160
the influence of dietary fish-oil supplementation on cutaneous leishmania amazonensis infection in mice.dietary fish-oil (fo) supplementation has been shown to inhibit inflammation in various clinical disease states and to be beneficial in experimental models of inflammation and bacterial and plasmodial infection. in mice, fo increases macrophage production of tumour necrosis factor alpha (tnf). production of tnf has been reported to be important in the resistance of mice against various leishmania spp. we investigated whether dietary supplementation with fo protects susceptible balb/c mice agains ...200212393167
bioactivity of crude extracts and some constituents of blutaparon portulacoides (amaranthaceae).crude extracts (aerial parts and roots, both dried), methylenedioxyflavonol, and a mixture of acyl steryl glycosides isolated from blutaparon portulacoides, were assayed for their toxicity against trypanosoma cruzi trypomastigotes and leishmania amazonensis amastigotes from axenic cultures. the antimicrobial activity was also investigated, in a screening conducted using fifteen strains of gram-positive and gram-negative bacteria, along with the yeasts, candida albicans and candida tropicalis. to ...200212403168
total synthesis and anti-leishmanial activity of some curcumin analogues.curcumin (1) an important yellow dye isolated from curcuma longa rhizomes, exhibits a variety of pharmacological effects such as anti-inflammatory, antioxidant and antiviral activity. ten curcuminoids (2-11) were synthesized by the condensation of 2,4-pentanedione with differently substituted benzaldehydes, using the boron complex approach, which avoided knoevenagel condensation at c-3 of the diketone. the curcuminoids were assayed in vitro against leishmania amazonensis promastigotes using pent ...200212404885
3-[4'-bromo-(1,1'-biphenyl)-4-yl]-n, n-dimethyl-3-(2-thienyl)-2-propen-1-amine: synthesis, cytotoxicity, and leishmanicidal, trypanocidal and antimycobacterial activities.current therapies for chagas' disease, leishmaniasis and tuberculosis are unsatisfactory because of the failure rates, significant toxicity and/or drug resistance. in this study, the compound 3-[4'-bromo-(1,1'-biphenyl)-4-yl]-n,n-dimethyl-3-(2-thienyl)-2-propen-1-amine (iv) was synthesized and its trypanocidal, leishmanicidal and antimycobacterial activities were investigated. the cytotoxicity was determined on v79 cells with three endpoints: nucleic acid content, 3-(4,5-dimethylthiazole-2-yl)-2 ...200212407118
assessment of pcr in the detection of leishmania spp in experimentally infected individual phlebotomine sandflies (diptera: psychodidae: phlebotominae).dna amplification by the polymerase chain reaction (pcr) was applied in the investigation of the presence of leishmania (kinetoplastida: trypanosomatidae) parasites in single phlebotomine sandflies. three phlebotomine/parasite pairs were used: lutzomyia longipalpis/leishmania chagasi, lutzomyia migonei/leishmania amazonensis and lutzomyia migonei/leishmania braziliensis, all of them incriminated in the transmission of visceral or cutaneous leishmaniasis. dna extraction was performed with whole i ...200212436164
leishmania (leishmania) amazonensis-induced cutaneous leishmaniasis in the primate cebus apella: a model for vaccine trials.a primate model of leishmaniasis was developed with the objective of future vaccine testing. lesion development and immunological parameters were studied upon primary and secondary infections. seven cebus apella were injected subcutaneously with 2 x 10(6) leishmania (leishmania) amazonensis promastigotes. erythematous nodules appeared 19-29 days p.i., which disappeared 100 days p.i. four months later, six of the monkeys were challenged with the same inoculum; three of them developed erythematous ...200212464422
a putative novel nuclear-encoded subunit of the cytochrome c oxidase complex in trypanosomatids.a relatively large nuclear-encoded polypeptide, designated trcoiv, is found in the cytochrome c oxidase (co) complex of trypanosomatids. in order to determine if this polypeptide represents a bona fide subunit of the complex, we have characterized the cdna and the gene for this polypeptide in leishmania tarentolae. its nuclear gene has no sequence similarity to mammalian coiv. the trcoiv preprotein has a long mitochondrial targeting sequence of 31 residues. the mature polypeptide cofractionates ...200212467979
biochemical analysis of proteins and lipids found in parasitophorous vacuoles containing leishmania amazonensis.one fundamental step of leishmania-macrophage interaction is the phase of parasite internalization through an endocytic process, with the formation of the parasitophorous vacuole (pv). the present study analyzed this process using two approaches. first, to investigate the host cell proteins which take part in this compartment, the macrophage surface was biotinilated and allowed to interact with both leishmania forms, the pv was then isolated, and the biotinilated proteins were analyzed by wester ...200312489012
effect of hydroxyurea on the intracellular multiplication of toxoplasma gondii, leishmania amazonensis and trypanosoma cruzi.toxoplasma gondii, leishmania amazonensis and trypanosoma cruzi are obligate intracellular parasites that multiply until lysis of host cells. the present study was undertaken to evaluate the effect of hydroxyurea (an inhibitor of cell division at the g1/s phase) on the multiplication of l. amazonensis, t. gondii, and t. cruzi in infected host cells. infected cells were treated with hydroxyurea (4 mm) for 48 h. hydroxyurea arrested intracellular multiplication of all infective forms of the parasi ...200312532228
new pcr assay using glucose-6-phosphate dehydrogenase for identification of leishmania species.glucose-6-phosphate dehydrogenase (g6pd) is one of the multilocus enzymes used to identify leishmania by zymodeme analysis. the polymorphic pattern revealed by partial characterization of the gene encoding g6pd generated molecular markers useful in the identification of different leishmania species by pcr. initially degenerate oligonucleotides were designed on the basis of data on the conserved active center described for other organisms. primers for reverse transcription-pcr experiments, design ...200312574243
effect of amidine derivatives on nitric oxide production by leishmania amazonensis promastigotes and axenic amastigotes.the effects of pentamidine isethionate (reference drug) and n,n'-diphenyl-4-methoxy-benzamidine (test compound) on no. production by leishmania amazonensis promastigotes and axenic amastigotes were investigated by measuring nitrite, a by-product of nitric oxide released into culture supernatants. the no. production by infective promastigotes was inhibited by och(3)-amidine in about 23.53% and by pentamidine in only 3.78%. in axenic amastigotes, the inhibition of no. production by och(3)-amidine ...200312586535
a microplate assay for leishmania amazonensis promastigotes expressing multimeric green fluorescent protein.convenient and economical assays capable of screening many compounds are vital to advance the development of drug therapy. this is particularly important for many of the infections that occur mainly in the third world. the development of such a spectrofluorometric assay for the protozoan parasite leishmania is presented here. using multimeric (four monomers) green fluorescent protein (gfp), leishmania amazonensis promastigotes were generated with brightness measurable in 96-well microtiter plate ...200312632163
growth phase and medium ph modulate the expression of proteinase activities and the development of megasomes in axenically cultivated leishmania (leishmania) amazonensis amastigote-like organisms.leishmania (leishmania) amazonensis lv79 (mpro/br/72/m1841) has been adapted to grow at 33 c as amastigote-like (al) organisms in modified um-54 medium initially adjusted to a ph of 4.8-5.0. axenic cultures could be routinely restarted from parasites recovered from footpad lesions obtained by inoculation of balb/c mice with preadapted culture stages. morphological features, proteinase activities, and infectivity of al organisms were examined during the in vitro growth cycle, and differences were ...200312659300
leishmania model for microbial virulence: the relevance of parasite multiplication and pathoantigenicity.leishmanial mechanisms of virulence have been proposed previously to involve two different groups of parasite molecules. one group consists of largely surface and secretory products, and the second group includes intracellular molecules, referred to as 'pathoantigens'. in the first group are invasive/evasive determinants, which protect not only parasites themselves, but also infected host cells from premature cytolysis. these determinants help intracellular amastigotes maintain continuous infect ...200312659975
bioactive alkyl phenols and embelin from oxalis erythrorhiza.the benzoquinone embelin and four alkyl phenols were isolated from an argentinean collection of oxalis erythrorhiza. 3-heptadecyl-5-methoxy-phenol is reported for the first time. the structures were determined by spectroscopic methods. embelin presented inhibitory effect on methicillin-resistant staphylococcus aureus, escherichia coli and the dermatophytic fungi epidermophyton floccosum, microsporum canis, microsporum gypseum, trichophyton mentagrophytes and trichophyton rubrum with mics ranging ...200312963150
effect of l-arginine analogs and a calcium chelator on nitric oxide (no) production by leishmania sp.leishmania amazonensis, l. braziliensis and l. chagasi promastigotes were grown in the presence of l-arginine analogs such as nomega-nitro-l-arginine methyl ester (l-name), ng-nitro-l-arginine (l-nna) and d-arginine (an inactive l-arginine isomer), besides an intracellular calcium chelator [ethylene glycol-bis (beta-aminoethyl ether)-n,n,n',n'-tetra acetic acid; egta] to verify the importance of l-arginine metabolism and the cofactors for these parasites. the parasite's growth curve was followed ...200314692512
[in vivo terbinafine inefficacy on cutaneous leishmaniasis caused by leishmania (leishmania) amazonensis in c57bl/6 mice].the efficiency of terbinafine was tested in c57bl/6 mice inoculated with the leishmania (leishmania) amazonensis strain mhom/br/ph8. the mice were administered: terbinafine at a dose of 100mg/kg/d by via oral; 0.9% saline solution orally as the control; and subcutaneous sodium stibogluconate 400mg sbv/kg/d as gold standard, for 20 days. terbinafine was demonstrated to be ineffective when compared to the controls, using clinical and parasitological parameters and the limiting dilution assay.200312937735
cyclic 3'-5' guanosine monophosphate-dependent activity in leishmania amazonensis.although there are some data concerning the nitric oxide and the cyclic 3'-5'guanosine monophosphate (cgmp) signaling pathway in trypanosomatids, there is no report about the cgmp-dependent enzymatic activity identification. in this sense, a cgmp dependent activity was detected on soluble fraction from leishmania amazonensis promastigotes with a high metacyclic level. this information is valuable in order to explore the metabolic pathway of g kinase protein in this parasite.200312937761
efficacy of a diarylheptanoid derivative against leishmania amazonensis.the activity of several diarylheptanoid derivatives (curcuminoids) was previously evaluated against leishmania amazonensis promastigotes and among them the most active compound was the [1-(4-methoxy-phenyl)-7-(3,4-methoxy-4-hydroxy-phenyl)-1,6-heptadien-3, 5-dione]. this derivative was chosen to be assayed in vivo in a treatment trial. for these experiments, the curcuminoid compound was used in a concentration equivalent to the ic50/24 h, obtained from the previous study. balb/c mice were inocul ...200312937773
the role of interleukin-10 in susceptibility of balb/c mice to infection with leishmania mexicana and leishmania amazonensis.recent studies have demonstrated the critical role of il-10 in susceptibility to cutaneous and visceral leishmaniasis caused by leishmania major and leishmania donovani, respectively. to determine whether il-10 also plays a similar role in the susceptibility and pathogenesis of cutaneous leishmaniasis caused by the new world species, l. mexicana and l. amazonensis, we analyzed their course of infection in il-10-deficient balb/c mice and their wild-type counterparts. although il-10-deficient mice ...200314500669
intradermal inoculations of low doses of leishmania major and leishmania amazonensis metacyclic promastigotes induce different immunoparasitic processes and status of protection in balb/c mice.in order to simulate the natural long term parasitisms which may occur in mammals infected with leishmania, cutaneous leishmaniases due to leishmania major or leishmania amazonensis were induced using a model based on the inoculation of 10-1000 metacyclic promastigotes into the ear dermis of balb/c mice. the final outcome of these parasitisms was dependent upon the number of inoculated parasites. only some of the mice inoculated with ten parasites displayed cutaneous lesions, whereas most mice i ...200314527520
in vitro antiproliferative effects of several diaryl derivatives on leishmania spp.in a previous works searching for new drugs with high efficiency, we reported the in vitro and in vivo antileishmanial activity of a series of diarylheptanoid structurally related to curcumin against l. amazonensis. this work describes the in vitro antileishmanial activity of a new series of diarylheptanoids and diarylpentanoids derivatives. these drugs were assayed against leishmania amazonensis, l. braziliensis and l. chagasi promastigotes containing a high percentage of metacyclic forms and t ...200312673024
differential properties of cba/j mononuclear phagocytes recovered from an inflammatory site and probed with two different species of leishmania.while cba/j mice fail to be permissive to leishmania amazonensis-driven pathogenic processes, they heal easily following leishmania major infection. the early-phase events are crucial to the outcome of leishmania infection and it is known that macrophages (mphi) are important in infection control. in the present study we investigated the role of mphi in driving cba/j susceptibility to l. amazonensis. we performed kinetic studies and compared the capacity of l. amazonensis and l. major to infect ...200312706438
effect of glycosphingolipids purified from leishmania (leishmania) amazonensis amastigotes on human peripheral lymphocytes.the effect of purified glycosphingolipids from leishmania (leishmania) amazonensis on human lymphoproliferation, on expression of human lymphocyte and monocyte markers (cd3, cd4, cd8, cd14, cd19, and cd45), and on lymphocyte protein kinase c activity was analyzed.200312738650
antileishmanial activity of a linalool-rich essential oil from croton cajucara.the in vitro leishmanicidal effects of a linalool-rich essential oil from the leaves of croton cajucara against leishmania amazonensis were investigated. morphological changes in l. amazonensis promastigotes treated with 15 ng of essential oil per ml were observed by transmission electron microscopy; leishmanial nuclear and kinetoplast chromatin destruction, followed by cell lysis, was observed within 1 h. pretreatment of mouse peritoneal macrophages with 15 ng of essential oil per ml reduced by ...200312760864
perforin and gamma interferon are critical cd8+ t-cell-mediated responses in vaccine-induced immunity against leishmania amazonensis infection.previous studies have demonstrated that protection against new world leishmaniasis caused by leishmania amazonensis can be elicited by immunization with the developmentally regulated leishmania amastigote antigen, p-8. in this study, several independent experimental approaches were employed to investigate the protective immunological mechanisms involved. t-cell subset depletion experiments clearly indicate that elicitation of cd8(+) (as well as cd4(+)) effector responses is required for protecti ...200312761096
identification and purification of immunogenic proteins from nonliving promastigote polyvalent leishmania vaccine (leishvacin ).immunogenic proteins from nonliving promastigote polyvalent leishmania vaccine against american tegumentary leishmaniasis (leishvacin ), produced by biobr s (biochemistry of brazil ), montes claros, state of minas gerais, brazil, were identified and purified by polyacrylamide electrophoresis gel and electroelution. c57bl/10 mice were vaccinated with proteins with estimated molecular weights of 42, 46, 63, 66, 73, 87, 97, and 160kda in three doses of 30 g of each protein at 15-day intervals combi ...200312806454
applications of recombinant leishmania amazonensis expressing egfp or the beta-galactosidase gene for drug screening and histopathological analysis.leishmania amazonensis recombinants expressing the enhanced green fluorescent protein (egfp) gene or beta-galactosidase gene (lacz) were constructed for drug screening and histopathological analysis. the egfp or lacz in a leishmanial transfection vector, p6.5, was introduced into l. amazonensis promastigotes, and egfp or lacz-carrying recombinant l. amazonensis, la/egfp and la/lacz, respectively, were obtained. expression of egfp or lacz in both promastigotes and amastigotes could be clearly vis ...200312806885
immune responses induced by the leishmania (leishmania) donovani a2 antigen, but not by the lack antigen, are protective against experimental leishmania (leishmania) amazonensis infection.leishmania amazonensis is one of the major etiologic agents of a broad spectrum of clinical forms of leishmaniasis and has a wide geographical distribution in the americas, which overlaps with the areas of transmission of many other leishmania species. the lack and a2 antigens are shared by various leishmania species. a2 was previously shown to induce a potent th1 immune response and protection against l. donovani infection in balb/c mice. lack is effective against l. major infection, but no sig ...200312819086
impaired expression of inflammatory cytokines and chemokines at early stages of infection with leishmania amazonensis.infection of mice with leishmania major results in disease progression or resolution, largely depending on the genetic backgrounds of the mouse strains. infection with leishmania amazonensis, on the other hand, causes progressive cutaneous lesions in most inbred strains of mice. we hypothesized that deficient activation of early immune responses contributes to the pathogenesis in l. amazonensis-infected mice. to distinguish early molecular events that determine the outcome of leishmania infectio ...200312874303
characterization of the species- and stage-specificity of two monoclonal antibodies against leishmania amazonensis.leishmania metacyclogenesis is associated with changes in morphology, gene expression, and structural alterations of the lipophosphoglycan (lpg), the promastigote most abundant surface glycolipid. purification of metacyclics is accomplished using lectins or monoclonal antibodies (mabs) that exploit stage-specific differences in the lpg. besides, lpg displays extensive interspecies polymorphisms and is synthesized by promastigotes of all species investigated to date. in this work we studied the s ...200312880592
efficacy of 8-bromoguanosine against murine cutaneous leishmaniasis induced with leishmania amazonensis.in this study, we investigated the effect of 8-bromoguanosine (8brguo), an immunostimulatory compound, in a murine model of experimental cutaneous leishmaniasis.200312886049
central nervous system involvement in experimental infection with leishmania (leishmania) amazonensis.we describe the pathologic alterations of the central nervous system (cns) observed in experimental tegumentary leishmaniasis in balb/c and swiss mice. the mice were subcutaneously infected with 10(4) amastigotes of leishmania (leishmania) amazonensis. animals were killed and brains were removed for histologic and immunocytochemical studies. histologic examination showed that 66.6% of infected mice had a discrete hyperemia and inflammatory infiltrate in the meninges, composed of mononuclear cell ...200312887024
interferon-gamma-inducing oral vaccination with leishmania amazonensis antigens protects balb/c and c57bl/6 mice against cutaneous leishmaniasis.the induction of oral tolerance against disease-inducing antigens has emerged as a feasible strategy to prevent immunopathologies. in this study, we investigated the effect of oral immunization with whole antigens of leishmania amazonensis promastigotes (laag) on murine cutaneous leishmaniasis. we found that two oral doses with 100 microg laag rendered balb/c and c57bl/6 mice more resistant against subsequent infection with l. amazonensis. the oral vaccine also partially protected balb/c mice ag ...200312922080
abortive infection of lutzomyia longipalpis insect vectors by aflagellated ldarl-3a-q70l overexpressing leishmania amazonensis parasites.leishmania donovani adp-ribosylation factor-like protein 3a (ldarl-3a) is a small g protein isolated from the protozoan parasite l. donovani with no defined physiological function. previously [cuvillier, a., redon, f., antoine, j.-c., chardin, p., devos, t., and merlin, g. (2000) j cell sci 113: 2065-2074] we have shown that overexpression in l. amazonensis promastigotes of the mutated protein ldarl-3a-q70l, which remains constitutively associated with gtp, leads to the disappearance of the flag ...200312969377
biological behavior of leishmania (l.) amazonensis isolated from a human diffuse cutaneous leishmaniasis in inbred strains of mice.after a subcutaneous injection of 100000 purified amastigotes of an isolate from a diffuse case of cutaneous leishmaniasis caused by the mhom/br/76/ma-5 strain of leishmania amazonensis, three inbred mouse strains developed a progressive nodular lesion, which evolved to an ulcerated lesion. based on these data, mice of balb/c, c57bl/6 or c57bl/10 could be classified as susceptible. the majority of mice developed metastases in the footpads, ear, tail, nose and oral mucosa. amputation of the membe ...200312973675
oxidosqualene cyclase inhibitors as antimicrobial agents.small-molecule oxidosqualene cyclase (osc) inhibitors were found to be effective in assays against cloned osc-like enzymes from human pathogens. a combinatorial library was prepared and used to identify lead compounds that inhibit the growth of trypanosoma cruzi, leishmania mexicana amazonensis, and pneumocystis carinii in culture. selectivity for the microorganisms in preference to mammalian cells was observed.200313678402
leishmania (leishmania) amazonensis: differential expression of proteinases and cell-surface polypeptides in avirulent and virulent promastigotes.a comparative study of proteolytic enzymes and cell-surface protein composition in virulent and avirulent leishmania (leishmania) amazonensis promastigote forms was carried out using one- and two-dimensional dodecyl sulfate sodium-polyacrylamide gel electrophoresis (sds-page). the surface iodinated protein profiles showed two major polypeptides of 65-60 and 50-47 kda that were expressed in both virulent and avirulent promastigote forms. however, minor quantitative differences were observed in th ...200314552857
studies on quinones. part 38: synthesis and leishmanicidal activity of sesquiterpene 1,4-quinones.the reaction of (+)-euryfuran 1 with several benzo-, naphtho- and benzo[b]thiophene-1,4-quinones in acetic acid yields the corresponding euryfuryl-1,4-quinones 3, 5, 7, 8, 10, 12, and 14. the structure of compounds 7, 8, 12, and 14 was assigned through 2d nmr 1h-13c hmbc experiments. the influence of the acidity of the solvent upon the reactivity and regioselectivity of the quinones to the oxidative coupling reaction, is discussed. the in vitro activity of the euryfurylquinones and their corresp ...200314556786
dna immunization with the gene encoding p4 nuclease of leishmania amazonensis protects mice against cutaneous leishmaniasis.infection with the protozoan parasite leishmania amazonensis can cause diverse clinical forms of leishmaniasis. immunization with purified p4 nuclease protein has been shown to elicit a protective response in mice challenged with l. amazonensis and l. pifanoi. to explore the potential of a dna-based vaccine, we tested the l. amazonensis gene encoding p4 nuclease as well as adjuvant constructs encoding murine interleukin-12 (il-12) and l. amazonensis hsp70. susceptible balb/c mice were immunized ...200314573646
antibody subclass profile against leishmania braziliensis and leishmania amazonensis in the diagnosis and follow-up of mucosal leishmaniasis.sensitivities and specificities of igg subclasses-elisa and igg-indirect fluorescent antibody test (ifat) against leishmania braziliensis (lb) and l. amazonensis (la) antigens were determined in 17 patients with mucosal (ml) and 19 with muco-cutaneous (mcl) leishmaniasis. using ifat-igg both antigens gave high sensitivities and were statistically similar, being 89.5% with la and 100% with lb. using elisa, the highest sensitivity was achieved with total igg for ml (94.7% with both antigens) and m ...200314596966
leishmania amazonensis rab7 promotes toxicity of the amino acid ester leu-ome in amastigote megasomes. 200314599671
trypanothione reductase activity is prominent in metacyclic promastigotes and axenic amastigotes of leishmania amazonesis. evaluation of its potential as a therapeutic target.the activity of trypanothione reductase in leishmania amazonensis was evaluated and it was demonstrated that tr is expressed in the soluble fractions of infective promastigotes and amastigotes, while non-infective promastigotes expressed the enzyme at basal levels. this data allows an association of enzyme activity and the infective capacity of the parasite. we have also previously demonstrated that amidine compounds (n, n'-diphenyl-4-methoxy-benzamidine and pentamidine) were active against this ...200415202494
dendritic cells as host cells for the promastigote and amastigote stages of leishmania amazonensis: the role of opsonins in parasite uptake and dendritic cell maturation.in their mammalian hosts, leishmania are obligate intracellular parasites that mainly reside in macrophages. they are also phagocytosed by dendritic cells (dcs), which play decisive roles in the induction and shaping of t cell-dependent immune responses. little is known about the role of dcs in the leishmania life cycle. here, we examined the ability of mouse bone marrow-derived dcs to serve as hosts for l. amazonensis. both infective stages of leishmania (metacyclic promastigotes and amastigote ...200414657281
dynamics of polymorphism of acidocalcisomes in leishmania parasites.growth of leishmania mexicana amazonensis promastigotes in different culture media resulted in structurally and chemically different acidocalcisomes. when grown in sdm-79 medium, the promastigotes showed large spherical acidocalcisomes of up to 1.2 microm diameter distributed throughout the cell. x-ray microanalysis and elemental mapping of the organelles showed large amounts of oxygen, phosphorus, sodium, potassium, magnesium, calcium, and zinc. immunofluorescence microscopy using antisera rais ...200415138840
a cardiac myosin-specific autoimmune response is induced by immunization with trypanosoma cruzi proteins.trypanosoma cruzi is the protozoan parasite that causes chagas' heart disease, a potentially fatal cardiomyopathy prevalent in central and south america. infection with t. cruzi induces cardiac myosin autoimmunity in susceptible humans and mice, and this autoimmunity has been suggested to contribute to cardiac inflammation. to address how t. cruzi induces cardiac myosin autoimmunity, we investigated whether immunity to t. cruzi antigens could induce cardiac myosin-specific autoimmunity in the ab ...200415155647
down-regulation of gp63 in leishmania amazonensis reduces its early development in lutzomyia longipalpis.the zinc protease (gp63) of promastigotes was found to play a role in the sand fly part of the leishmania life cycle. lutzomyia longipalpis females were fed with promastigotes (10(6) per ml) of a leishmania amazonensis clone whose gp63 was up- and down-regulated by directional cloning into p6.5 for sense- and anti-sense transcription. early development was found to differ significantly between the sense- and anti-sense transfectants 2 days post-feeding. the sense transfectants overexpressing gp6 ...200415158771
subcellular localization of an extracellular serine protease in leishmania (leishmania) amazonensis.extracellular proteolytic activity was detected in a leishmania ( l.) amazonensis culture supernatant and a 56-kda protein was purified using (nh4)2so4 precipitation followed by affinity chromatography on aprotinin-agarose. a rabbit serum obtained against the 56-kda extracellular serine protease was used in order to analyze its location in l. ( l.) amazonensis parasites. immunocytochemistry studies revealed that the enzyme is mainly found in the flagellar pocket and cytoplasmic vesicles of proma ...200415185145
antileishmanial activity of isolated triterpenoids from pourouma guianensis.the inhibiting activity of triterpenoids isolated from the methanolic extract of pourouma guianensis (moraceae) leaves is described for promastigotes and intracellular amastigotes of leishmania amazonensis. whereas the fractions containing apigenin, friedelin, epi-friedelinol, arjunolic acid, hyptatic acid b, stigmasterol and sitosterol were of no or relatively low inhibitory activity, fractions containing tormentic acid, 2alpha,3beta-dihydroxyursan-12-en-28-oic acid, 2alpha,3beta-dihydroxyolean ...200415070160
antiprotozoal effect of crude extracts and flavonoids isolated from chromolaena hirsuta (asteraceae).phytochemical study of chromolaena hirsuta (hook. & arn.) r. king & h. robinson crude extract (collected in furnas, mg-brasil) produced fifteen flavonoids, two triterpenes and five steroids. ir, uv,(1)h and (13)c nmr spectroscopy and gc analysis were used for the identification of these compounds. the dichloromethanic and ethanolic crude extracts (flowers and leaves) and six flavonoids isolated from this specie have been assayed for antiprotozoal activity against tripomastigote forms of trypanos ...200415103676
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