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[immunoglobulin isotype and igg subclass profiles in american tegumentary leishmaniasis].the present work investigated the serum antibody profiles in 37 patients with american tegumentary leishmaniasis, who were attended at hospital de clinicas - universidade federal de uberlandia, mg, brazil. the immunoglobulin class and igg subclass profiles were analyzed by indirect elisa using leishmania (leishmania) amazonensis soluble antigen. the antibody avidity was determined by 6 m urea treatment after incubation with immunoenzymatic conjugate. it was observed that 97% of the serum samples ...200515821787
plant active components - a resource for antiparasitic agents?plant essential oils (and/or active components) can be used as alternatives or adjuncts to current antiparasitic therapies. garlic oil has broad-spectrum activity against trypanosoma, plasmodium, giardia and leishmania, and cochlospermum planchonii and croton cajucara oils specifically inhibit plasmodium falciparum and leishmania amazonensis, respectively. some plant oils have immunomodulatory effects that could modify host-parasite immunobiology, and the lipid solubility of plant oils might off ...200516099722
differences in morphology of phagosomes and kinetics of acidification and degradation in phagosomes between the pathogenic entamoeba histolytica and the non-pathogenic entamoeba dispar.phagocytosis plays an important role in the pathogenicity of the intestinal protozoan parasite entamoeba histolytica. we compared the morphology of phagosomes and the kinetics of phagosome maturation using conventional light and electron microscopy and live imaging with video microscopy between the virulent e. histolytica and the closely-related, but non-virulent e. dispar species. electron micrographs showed that axenically cultivated trophozoites of the two entamoeba species revealed morpholog ...200516106449
axenic promastigote forms of leishmania (viannia) lainsoni as an alternative source for leishmania antigen production.the present study demonstrates that axenic cultures of leishmania (viannia) lainsoni produce larger cell masses in nnn-lit medium, as well as higher amounts of total proteins in cell extracts, than leishmania (leishmania) amazonensis. antigenicity of l. (v.) lainsoni whole promastigotes is similar to that of l. (l.) amazonensis, as demonstrated by an indirect immunofluorescence diagnostic test using sera from human patients and dogs infected with visceral leishmaniasis. infectivity of the l. (v. ...200516108545
leishmania (viannia) braziliensis growth in vitro culture relies more on folic acid availability than leihsmania (leishmania) amazonensis.we compared the in vitro growth of promastigotes from two leishmania species in tc-100 and schneider media. leishmania (leishmania) amazonensis replication rates were similar in both tissue culture media and reached maximum rates by 48 h. in contrast leishmania (viannia) braziliensis growth was significantly greater in tc-100 but maximum rates were achieved by 96 h. folic acid appears to be the limiting factor and supplementation of schneider media with this nutrient improved l. (v.) braziliensi ...200516113874
subcellular localization of an intracellular serine protease of 68 kda in leishmania (leishmania) amazonensis promastigotes.here we report the subcellular localization of an intracellular serine protease of 68 kda in axenic promastigotes of leishmania (leishmania) amazonensis, using subcellular fractionation, enzymatic assays, immunoblotting, and immunocytochemistry. all fractions were evaluated by transmission electron microscopy and the serine protease activity was measured during the cell fractionation procedure using alpha-n-r-tosyl-l-arginine methyl ester (l-tame) as substrate, phenylmethylsulphone fluoride (pms ...200516113885
genomic organization of telomeric and subtelomeric sequences of leishmania (leishmania) amazonensis.telomeres are dna-protein complexes that protect linear chromosomes from degradation and fusions. telomeric dna is repetitive and g-rich, and protrudes towards the end of the chromosomes as 3'g-overhangs. in leishmania spp., sequences adjacent to telomeres comprise the leishmania conserved telomere associated sequences (lctas) that are around 100 bp long and contain two conserved sequence elements (csb1 and csb2), in addition to non-conserved sequences. the aim of this work was to study the geno ...200516126212
new clerodane diterpenoids from laetia procera (poepp.) eichler (flacourtiaceae), with antiplasmodial and antileishmanial activities.extracts of laetia procera (flacourtiaceae) displayed significant in vitro activity against plasmodium falciparum. p. falciparum bioassay guided fractionation of a trunk bark extract of this plant led to the isolation of six clerodane diterpenoids (1-6) and a butanolide (7). five of these compounds are new and called laetiaprocerine a-d (3-6) and laetianolide a (7). their structures were established on the basis of 1d and 2d nmr experiments. absolute configurations of 1 and 2 were determined by ...200516168652
further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by leishmania (leishmania) amazonensis.leishmania (leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of american cutaneous leishmaniasis (acl): localized cutaneous leishmaniasis (lcl), and anergic diffuse cutaneous leishmaniasis (adcl). recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (bdcl), was introduced into the clinical spectrum of acl caused by this parasite, and in this paper we record the clinical, histopathological, and immunolo ...200516184231
antiproliferative and ultrastructural effects of bpq-oh, a specific inhibitor of squalene synthase, on leishmania amazonensis.parasites of the leishmania genus require for the growth and viability the de novo synthesis of specific sterols as such as episterol and 5-dehydroepisterol because cholesterol, which is abundant in their mammalian hosts, does not fulfill the parasite sterol requirements. squalene synthase catalyzes the first committed step in the sterol biosynthesis and has been studied as a possible target for the treatment of high cholesterol levels in humans. in this work we investigated the antiproliferativ ...200516198340
[immunization with leishmania amazonensis subgenomic libraries protects balb/c mice against the challenge].a genomic library of leishmania amazonensis in expression vector of eukaryote cells (pef1hisa, pef1hisb, pef1hisc) was prepared. also two subgenomic libraries having each 500 clones approximately were created and balb/c mice were immunized with 50 mg/0,1 ml of dna from each. two immunizations were administered intramuscularly at 15-day interval. groups of control mice were immunized with dna from empty plasmid pef1his, with soluble parasite antigen (100 mg/0,1 ml) and saline solution. the size o ...200415846906
feline leishmaniasis due to leishmania (leishmania) amazonensis in mato grosso do sul state, brazil.a case of leishmaniasis in a domestic cat (felis domesticus) is described. the animal showed a single, nodular lesion on the nose and many nodules of different size on the ears and digital regions of all the paws. diagnosis was made by microscopic detection of amastigotes in giemsa-stained smears from the lesions. by monoclonal antibodies the aetiological agent was identified as leishmania (leishmania) amazonensis, one of the seven species implicated in human leishmaniasis in brazil. the clinica ...200415725531
a new heptasubstituted (e)-aurone glucoside and other aromatic compounds of gomphrena agrestis with biological activity.a new aurone 1 and two known substances, aurantiamide acetate (2) and tiliroside (3), were isolated from the ethanolic extract of gomphrena agrestis. the structural determination of 1 was based on spectroscopic and spectrometric data. the substance was defined as (e)-3'-o-beta-d-glucopyranosyl-4,5,6,4'-tetrahydroxy-7,2'-dimethoxyaurone. biological activity of the ethanolic crude extract and isolated compounds against bacteria, fungi and leishmania amazonensis amastigotes was evaluated. this appe ...200415813368
a serine protease from a detergent-soluble extract of leishmania (leishmania) amazonensis.proteases mediate important crucial functions in parasitic diseases, and their characterization contributes to the understanding of host-parasite interaction. a serine protease was purified about 43-fold with a total recovery of 60% from a detergent-soluble extract of promastigotes of leishmania amazonensis. the purification procedures included aprotinin-agarose affinity chromatography and gel filtration high performance liquid chromatography. the molecular mass of active enzyme was 110 kda by n ...200415813385
immunomodulatory effect of canova medication on experimental leishmania amazonensis infection.this study investigates the action of canova medication (cm) on experimental infection by leishmania (leishmania) amazonensis, utilizing in vitro and in vivo assays. for the in vitro tests, balb/c mouse peritoneal macrophages (5x10(5) cells in 500 microl of culture medium, supplemented with 10% fetal calf serum, penicillin (100 u/ml) and streptomycin (0.1 mg/ml) (were distributed in 24-well plates and cm was added at concentrations of 20 or 40%. twenty-four hours later, the macrophages were infe ...200416038768
2-propen-1-amine derivatives and their synthetic intermediates: activity against pathogenic trypanosomatids.the potential activity of three new derivatives of 3-(4'-y-[1,1'-biphenyl]-4-yl)-3-(4-x-phenyl)-n,n-dimethyl-2-propen-1-amine (2-pams) was assayed against trypanosoma cruzi and leishmania amazonensis. they showed higher activity against trypomastigotes and epimastigotes of t. cruzi than the standard drugs, crystal violet and nifurtimox. besides these derivatives, a series of eleven 2-pams derivatives and the corresponding intermediates, biphenyl methanones (bpms) were assayed against promastigot ...200415700843
leishmania amazonensis: early proteinase activities during promastigote-amastigote differentiation in vitro.leishmania proteinase activity is known as parasite differentiation marker, and has been considered relevant for leishmanial survival and virulence. these properties suggest that leishmania proteinases can be promising targets for development of anti-leishmania drugs. here, we analyze the activities of four proteinases during the early phase of the leishmania amazonensis promastigotes differentiation into amastigotes induced by heat shock. we have examined activities of cysteine-, metallo-, seri ...200415639138
an effective diaryl derivative against leishmania amazonensis and its influence on the parasite x macrophage interaction.the activity of several diarylheptanoid derivatives (curcuminoids) was previously evaluated against leishmania amazonensis promastigotes and among them the most active compound was 5-hydroxy-7- (4-hydroxy-3-methoxyphenyl)-1-(4-methoxyphenyl)-1,4,6-heptatrien-3-one. this study was carried out to investigate the influence of this diaryl derivative on the infective promastigotes and balb/c mice peritoneal macrophage interaction. the potential in vitro toxicity was also evaluated. promastigotes pret ...200415648659
activity of a paromomycin hydrophilic formulation for topical treatment of infections by leishmania (leishmania) amazonensis and leishmania (viannia) braziliensis.studies on in vitro skin permeation and in vivo anti-leishmanial activity in mice experimentally infected with leishmania (leishmania) major pointed out to the potential of a new paromomycin (pa) formulation (hydrophilic gel) for treatment of cutaneous leishmaniasis (cl). in this study, the activity of this formulation was evaluated in animals experimentally infected by leishmania species that prevail in the new world. pa gel activity was compared to antimony treatment, since it is still the fir ...200415652330
screening of new caledonian and vanuatu medicinal plants for antiprotozoal activity.sixty-seven extracts of 30 medicinal plants traditionally used in new caledonia or vanuatu by healers to treat inflammation, fever and in cicatrizing remedies were evaluated in vitro for their antiprotozoal activity against leishmania donovani, leishmania amazonensis and trypanosoma cruzi. among the selected plants, pagiantha cerifera was the most active against both leishmania species; four extracts were active against promastigotes of leishmania donovani at ec(50) values inferior to 5 microg/m ...200415619580
hypoxia modulates expression of the 70-kd heat shock protein and reduces leishmania infection in macrophages.hypoxia, a microenvironmental factor present in diseased tissues, has been recognized as a specific metabolic stimulus or a signal of cellular response. experimental hypoxia has been reported to induce adaptation in macrophages such as differential migration, elevation of proinflammatory cytokines and glycolytic enzyme activities, and decreased phagocytosis of inert particles. in this study we demonstrate that although exposure to hypoxia (5% o2, 5% co2, and balanced n2) did not change macrophag ...200415591782
cell structure and cytokinesis alterations in multidrug-resistant leishmania (leishmania) amazonensis.multidrug-resistant leishmania (leishmania) amazonensis may be obtained by in vitro selection with vinblastine. in order to determine whether this phenotype is linked to structural alterations, we analyzed the cell architecture by electron microscopy. the vinblastine resistant cl2 clone of l. (l.) amazonensis, but not wild-type parasites, showed a cytokinesis dysfunction. the cl2 promastigotes had multiple nuclei, kinetoplasts and flagella, suggesting that vinblastine resistance may be associate ...200415592939
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
identification of three proteins that associate in vitro with the leishmania (leishmania) amazonensis g-rich telomeric strand.the chromosomal ends of leishmania (leishmania) amazonensis contain conserved 5'-ttaggg-3' telomeric repeats. protein complexes that associate in vitro with these dna sequences, leishmania amazonensis g-strand telomeric protein (lagt1-3), were identified and characterized by electrophoretic mobility shift assays and uv cross-linking using protein fractions purified from s100 and nuclear extracts. the three complexes did not form (a) with double-stranded dna and the c-rich telomeric strand, (b) i ...200415233802
destiny and intracellular survival of leishmania amazonensis in control and dexamethasone-treated glial cultures: protozoa-specific glycoconjugate tagging and tunel staining.leishmania amazonensis, an obligatory intracellular parasite, survives internalization by macrophages, but no information is available on the involvement of microglia. we have investigated microglia-protozoa interactions in mixed glial cultures infected with promastigote forms of l. amazonensis after lipopolysaccharide (lps) or dexamethasone (dm) treatment. after 2 hr of exposure to parasites in control cultures, there was a small number of infected microglia (1%). preincubation with lps or dm l ...200415258180
effect of hypoxia on macrophage infection by leishmania amazonensis.in the present study, we compared the effect of 5% oxygen tension (hypoxia) with a normal tension of 21% oxygen (normoxia) on macrophage infection by the protozoan parasite leishmania amazonensis. macrophages from different sources (human cell line u937, murine cell line j774, and murine peritoneal macrophages) exposed to hypoxia showed a reduction of the percentage of infected cells and the number of intracellular parasites per cell. observations on the kinetics of infection indicated that hypo ...200415270094
cd4+ th1 cells induced by dendritic cell-based immunotherapy in mice chronically infected with leishmania amazonensis do not promote healing.the susceptibility of mice to leishmania amazonensis infection is thought to result from an inability to develop a th1 response. our data show that the low levels of gamma interferon (ifn-gamma) produced by the draining lymph node (dln) cells of chronically infected mice could be enhanced in vitro and in vivo with l. amazonensis antigen-pulsed bone marrow-derived dendritic cells (bm-dc) and the th1-promoting cytokine interleukin-12 (il-12). given intralesionally to chronically infected mice, thi ...200415271903
intranasal vaccination against cutaneous leishmaniasis with a particulated leishmanial antigen or dna encoding lack.we have previously demonstrated that oral delivery of a disease-promoting particulated antigen of leishmania amazonensis (laag) partially protects mice against cutaneous leishmaniasis. in the present work, we sought to optimize a mucosal vaccine by using the intranasal route for delivery of different antigen preparations, including (i) laag, (ii) soluble recombinant p36/lack leishmanial antigen (lack), and (iii) plasmid dna encoding lack (lack dna). balb/c mice that received two intranasal doses ...200415271911
novel azasterols as potential agents for treatment of leishmaniasis and trypanosomiasis.this paper describes the design and evaluation of novel azasterols as potential compounds for the treatment of leishmaniasis and other diseases caused by trypanosomatid parasites. azasterols are a known class of (s)-adenosyl-l-methionine: delta24-sterol methyltransferase(24-smt) inhibitors in fungi, plants, and some parasitic protozoa. the compounds prepared showed activity at micromolar and nanomolar concentrations when tested against leishmania spp. and trypanosoma spp. the enzymatic and stero ...200415273104
effect of thiadiazine derivatives on intracellular amastigotes of leishmania amazonensis.current therapy for leishmaniasis is not satisfactory. we describe the in vitro antiproliferative effects of new thiadiazine derivatives against leishmania amazonensis. the compounds were found to be active against the amastigote form of the parasite, inhibiting parasite growing, from 10 to 89%, at a concentration of 100 ng/ml. this activity suggests that thiadiazine derivatives could be considered as potential antileishmanial compounds.200415273809
phenyl substitution of furamidine markedly potentiates its anti-parasitic activity against trypanosoma cruzi and leishmania amazonensis.furamidine (db75) and related unfused aromatic diamidines have proven useful for the treatment of parasitic infections. these compounds were primarily developed to combat infections by pneumocystis carinii and african trypanosomes but they are also active against other parasites. here we have investigated the in vitro effects of db75 and its phenyl-substituted analog db569 on two kinetoplastid haemoflagellates trypanosomatidae: trypanosoma cruzi and leishmania (l) amazonensis. the phenyl-amidine ...200415276066
th1 and th2 immunological profile induced by cysteine proteinase in murine leishmaniasis.this study evaluated the immune response to three synthetic peptides (pi, vmveqvicfd; pii, vggglcfe; piii, pyflgsimntchyt) from the cooh-terminal region of leishmania amazonensis cysteine proteinases, in balb/c- and cba-infected mice with this parasite. only balb/c mice, previously inoculated with pi, showed a distinct exacerbation of the lesion. blastogenesis assays were performed with lymph node cells from the group of mice infected with l. amazonensis, but not inoculated with the peptides, an ...200415279623
il-5-induced eosinophils suppress the growth of leishmania amazonensis in vivo and kill promastigotes in vitro in response to either il-4 or ifn-gamma.in il-5 transgenic mice (c3h/hen-tgn(il-5)-imeg), in which 50% of peripheral blood leukocytes are eosinophils, the development of infection by leishmania amazonensis was clearly suppressed. to determine mechanistically how this protozoan parasite is killed, we performed in vitro killing experiments. either il-4 or ifn-gamma effectively stimulated eosinophils to kill leishmania amazonensis promastigotes, and most of the killing was inhibited by catalase but not by the no inhibitor l-n5-(1-iminoet ...200415294090
effect of the lysophospholipid analogues edelfosine, ilmofosine and miltefosine against leishmania amazonensis.analysis of the effect of edelfosine, ilmofosine and miltefosine on leishmania amazonensis and of potential targets of these lysophospholipid analogues.200415329361
the t-cell anergy induced by leishmania amazonensis antigens is related with defective antigen presentation and apoptosis.leishmania amazonensis is the main agent of diffuse cutaneous leishmaniasis, a disease associated with anergic immune responses. in this study we show that the crude antigen of leishmania amazonensis (laag) but not l. braziliensis promastigotes (lbag) contains substances that suppress mitogenic and spontaneous proliferative responses of t cells. the suppressive substances in laag are thermoresistant (100 degrees c/1h) and partially dependent on protease activity. t cell anergy was not due to a d ...200415334250
characterisation of a new leishmania meta gene and genomic analysis of the meta cluster.the meta1 gene of leishmania is upregulated in metacyclic promastigotes and encodes a 12 kda virulence-related protein, conserved in all leishmania species analysed. in this study, the genomic region adjacent to the leishmania amazonensis meta1 gene was characterised and compared to the leishmania major meta1 locus as well as to syntenic loci identified in trypanosoma brucei and trypanosoma cruzi. three new genes expressed with increased abundance of steady state mrna in l. amazonensis promastig ...200415336424
protein kinase a activity is associated with metacyclogenesis in leishmania amazonensis.because of the importance of cell signalling processes in proliferation and differentiation, the adenylate cyclase pathway was studied, specifically the protein kinase a (pka) in leishmania amazonensis. the pkas of soluble (sf) and enriched membrane fractions (mf) from infective/non-infective promastigotes and axenic amastigotes were assayed. in order to purify the pka molecule, fractions were chromatographed on deae-cellulose columns and the phosphorylative activity was evaluated using [gamma(3 ...200415338471
does the leishmania major paradigm of pathogenesis and protection hold for new world cutaneous leishmaniases or the visceral disease?parasitic protozoa of the genus leishmania have provided a useful perspective for immunologists in terms of host defense mechanisms critical for the resolution of infection caused by intracellular pathogens. these organisms, which normally reside in a late endosomal, major histocompatibility complex (mhc) class ii(+) compartment within host macrophages cells, require cd4(+) t-cell responses for the control of disease. the paradigm for the cd4(+) t-helper 1 (th1)/th2 dichotomy is largely based on ...200415361243
leishmania (leishmania) amazonensis: purification and characterization of a promastigote serine protease.pathogenic protozoan proteases play crucial roles in the host-parasite interaction, and its characterization contributes to the understanding of protozoan disease mechanisms. a leishmania amazonensis promastigote protease was purified 36-fold, using aprotinin-agarose affinity chromatography and gel filtration high performance liquid chromatography, yielding a total recovery of 49%. the molecular mass of active enzyme obtained from native gel filtration hplc and sds-page under conditions of reduc ...200415363943
immune response induced by new world leishmania species in c57bl/6 mice.in the present study, c57bl/6 mice were inoculated with metacyclic leishmania amazonensis or l. braziliensis promastigotes. while these animals were capable of controlling the infection by l. braziliensis, they developed chronic lesions with elevated numbers of parasites when infected by l. amazonensis. the differences in parasite control were associated with a decreased production of ifn-gamma and tnf by lymph node cells from l. amazonensis-infected mice. furthermore, these animals presented de ...200415378352
influence of h2 complex and non-h2 genes on progression of cutaneous lesions in mice infected with leishmania amazonensis.susceptibility to infection with leishmania amazonensis promastigotes was examined in six b10 congenic mouse strains, including c57bl/10j (h2b), b10.br (h2k), b10.m (h2f), b10.s (h2s), b10.riii (h2r), and b10.d2 (h2d). all strains of mice developed skin nodules with punch-out ulcers by 8 weeks post-infection, but b10.m and b10.s mice showed resolution of cutaneous leishmaniasis lesions by 16 weeks post-infection. in addition, the skin lesions were much larger in balb congenic mice than in b10 an ...200415468528
toxoplasma gondii exposes phosphatidylserine inducing a tgf-beta1 autocrine effect orchestrating macrophage evasion.toxoplasmosis is a worldwide disease caused by toxoplasma gondii. activated macrophages control t. gondii growth by nitric oxide (no) production. however, t. gondii active invasion inhibits no production, allowing parasite persistence. here we show that the mechanism used by t. gondii to inhibit no production persisting in activated macrophages depends on phosphatidylserine (ps) exposure. masking ps with annexin-v on parasites or activated macrophages abolished no production inhibition and paras ...200415474490
antileishmanial pyrazolopyridine derivatives: synthesis and structure-activity relationship analysis.three series of 4-anilino-1h-pyrazolo[3,4-b]pyridine-5-carboxylic esters were synthesized as part of a program to study potential anti-leishmania drugs. these compounds were obtained by a condensation reaction of 4-chloro-1h-pyrazolo[3,4-b]pyridine with several aniline derivatives. some of them were also obtained by an alternative pathway involving a mannich-type reaction. the hydrophobic parameter, log p, was determined by shake-flask methodology, and using the hansch-fujita addictive hydrophob ...200415481980
protection of c3heb/fej mice against leishmania amazonensis challenge after previous leishmania major infection.the th1 response elicited in mice infected with leishmania major has been used as a model to characterize cellular immune defects associated with l. amazonensis infection. however, it is not known if the immune response associated with the infection by virulent l. major parasites can promote resistance to a subsequent l. amazonensis infection. our data demonstrate that c3heb/fej mice infected subcutaneously with virulent l. major are resistant to an l. amazonensis challenge. the healing phenotyp ...200415516635
trypanosomatid flagellum biogenesis: arl-3a is involved in several species.overexpression in leishmania amazonensis promastigotes of the gtpase-deficient small g protein ldarl-3a-q70l specifically provokes the loss of the flagella without affecting cell viability and body size. however, motility is lost and, remarkably, cells do not survive in the insect vector lutzomyia longipalpis gut, leading to interruption of parasite transmission. we report here that overexpression of the same protein in leishmania major, leishmania donovani, and crithidia fasciculata also led to ...200415582509
oral delivery of meglumine antimoniate-beta-cyclodextrin complex for treatment of leishmaniasis.the need for daily parenteral administration represents one of the most serious limitations in the clinical use of pentavalent antimonials against leishmaniasis. in this work, we investigated the ability of beta-cyclodextrin to enhance the oral absorption of antimony and to promote the oral efficacy of meglumine antimoniate against experimental cutaneous leishmaniasis. the occurrence of interactions between beta-cyclodextrin and meglumine antimoniate was demonstrated through the changes induced ...200414693525
pcr-rflp to identify leishmania (viannia) braziliensis and l. (leishmania) amazonensis causing american cutaneous leishmaniasis.a pcr-rflp based method was developed to diagnose and identify the leishmania species causing american cutaneous leishmaniasis (acl) in a panel of clinical samples obtained from an endemic region of brazil. the comparison of the results obtained by pcr-rflp and pcr-hybridization in the identification of leishmania (viannia) braziliensis and l. (leishmania) amazonensis were highly concordant (kappa=91.5%). the pcr-rflp method was reliable, fast and easy to conduct on biopsies and presents potenti ...200414739020
enhanced replication of leishmania amazonensis amastigotes in gamma interferon-stimulated murine macrophages: implications for the pathogenesis of cutaneous leishmaniasis.during leishmania major infection in mice, gamma interferon (ifn-gamma) plays an essential role in controlling parasite growth and disease progression. in studies designed to ascertain the role of ifn-gamma in leishmania amazonensis infection, we were surprised to find that ifn-gamma could promote l. amazonensis amastigote replication in macrophages (mphis), although it activated mphis to kill promastigotes. the replication-promoting effect of ifn-gamma on amastigotes was independent of the sour ...200414742545
cryopreservation of protozoan parasites.conventional methods for the propagation and preservation of parasites in vivo or in vitro have some limitations, including the need for labor, initial isolation and loss of strains, bacterial, and fungal contamination, and changes in the original biological and metabolic characteristics. all these disadvantages are considerably reduced by cryopreservation. in this study, we examined the effects of various freezing conditions on the survival of several protozoan parasites after cryopreservation. ...200414969677
sand fly saliva enhances leishmania amazonensis infection by modulating interleukin-10 production.after transmission through the bite of female sand flies, leishmania spp. can cause a broad spectrum of disease manifestations collectively known as leishmaniases. l. amazonensis is endemic in south america, where it causes cutaneous, diffuse cutaneous, and visceral leishmaniasis. in this study, we have provided evidence that salivary gland extracts (sge) of lutzomyia longipalpis enhances l. amazonensis infection. balb/c mice infected intradermally in the ear with 10(5) metacyclic promastigotes ...200414977924
safety, immunogenecity, and efficacy of an autoclaved leishmania amazonensis vaccine plus bcg adjuvant against new world cutaneous leishmaniasis.the safety, immunogenecity, and efficacy of two doses of an autoclaved-killed, whole cell leishmania amazonensis vaccine (ifla/br/67/ph8) and bcg adjuvant (n = 750) against cutaneous leishmaniasis (cl) was compared with placebo (n = 756) in a randomized, placebo-controlled, blinded study. systemic and local side-effects were more frequent in the vaccine than placebo group. leishmanin skin test (lst) conversion was greater in the vaccine than placebo group 2 months after the second vaccination do ...200415003662
overexpression of lamdr2, a novel multidrug resistance atp-binding cassette transporter, causes 5-fluorouracil resistance in leishmania amazonensis.the atp-binding cassette (abc) proteins play an important role in drug resistance and detoxification in various organisms. here we isolated lamdr2, a new member of the multidrug resistance (mdr) subfamily of abc proteins in leishmania amazonensis. lamdr2 exhibited 47% amino acid identity to its most closely related protein, lamdr1, which was previously isolated from the same species. promastigotes that overexpressed lamdr2 showed significant resistance to 5-fluorouracil (5-fu), but not to lamdr1 ...200415013779
identification and molecular characterization of a gene encoding a protective leishmania amazonensis trp-asp (wd) protein.several leishmania proteins have been identified and characterized in pursuit of understanding pathogenesis and protection in cutaneous leishmaniasis. in the present study, we utilized sera from infected balb/c mice to screen a leishmania amazonensis amastigote cdna expression library and obtained the full-length gene that encodes a novel trp-asp (wd) protein designated lawd (for leishmania antigenic wd protein). the wd family of proteins mediates protein-protein interactions and coordinates the ...200415039343
leishmanicidal activity of polyphenolic-rich extract from husk fiber of cocos nucifera linn. (palmae).the available therapy for leishmaniasis, which affects 2 million people per annum, still causes serious side effects. the polyphenolic-rich extract from the husk fiber of cocos nucifera linn. (palmae) presents antibacterial and antiviral activities, also inhibiting lymphocyte proliferation, as shown by our group in previous works. in the present study, the in vitro leishmanicidal effects of c. nucifera on leishmania amazonensis were evaluated. the minimal inhibitory concentration of the polyphen ...200415059625
the role of complement in the early phase of leishmania (leishmania) amazonensis infection in balb/c mice.complement-depleted and -non-depleted balb/c mice were inoculated with leishmania (leishmania) amazonensis promastigotes into the hind footpad to study the role of the complement system in cutaneous leishmaniasis. total serum complement activity was measured by hemolytic assay and c3 fragment deposit at the inoculation site was determined by direct immunofluorescence in the early period of infection, i.e., at 3, 24, 48 h and 7 days post-infection. the inflammatory reaction and the parasite burde ...200415060713
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
histopathological studies of visceralized leishmania (leishmania) amazonensis in mice experimentally infected.balb/c, c57bl/6, and dba/2 mice were subcutaneously infected in the left footpad by injecting 10(4) leishmania (leishmania) amazonensis amastigotes. mice were sacrificed 20, 30, 40, 60 and 90 days post-infection. fragments of liver, kidney, spleen, skin, and draining lymph node were collected for histological examination. light microscopy showed that at 20 days after infection balb/c mice presented discrete inflammatory infiltrates in the skin made up of eosinophils, lymphocytes, and rare parasi ...200415135858
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
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
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
[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
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
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
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
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
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
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
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
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
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
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