Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| effect of acidic ph on heat shock gene expression in leishmania. | temperature and ph shifts trigger differential gene expression and stage transformation in leishmania. the parasites encounter dramatic fluctuations in the extra-cellular ph between the mid-gut of the sand fly (ph>8) and the phagolysosomal vacuole of mammalian macrophages (ph<6). the authors examined the effect of ph shifts on heat shock gene expression in leishmania amazonensis and leishmania donovani promastigotes. acidic ph resulted in preferential stability of the hsp83 transcripts at 26 deg ... | 1999 | 10376997 |
| h-2m molecules, like mhc class ii molecules, are targeted to parasitophorous vacuoles of leishmania-infected macrophages and internalized by amastigotes of l. amazonensis and l. mexicana. | in their amastigote stage, leishmania are obligatory intracellular parasites of mammalian macrophages, residing and multiplying within phagolysosomal compartments called parasitophorous vacuoles (pv). these organelles have properties similar to those described for the mhc class ii compartments of antigen-presenting cells, sites where peptide-class ii molecule complexes are formed before their expression at the cell surface. after infection with leishmania amazonensis or l. mexicana, endocytosis ... | 1999 | 10393812 |
| systemic delivery of an adenovirus expressing ebv-derived vil-10 in mice infected with schistosoma mansoni or leishmania amazonensis: controversial effects on the development of pathological parameters. | within the context of microorganism/host interactions, those which last over weeks are expected to be sensitive to more or less sustained and targeted immuno-intervention, such as delivery of cytokines known to operate as down-regulators of acute inflammatory processes. il-10 has received growing attention as a potential tool in immunotherapy, due to its anti-inflammatory and immunosuppressive properties. therefore, using two experimental models of long-term interactions between parasites and la ... | 1999 | 10400822 |
| the anti-leishmanial effect of kalanchoe is mediated by nitric oxide intermediates. | we have previously shown that oral treatment with the leaf extract of the plant kalanchoe pinnata (kp) significantly decreases the lesion size and the parasite load in balb/c mice infected with leishmania amazonensis. here we report on the mode of action of kp, particularly on the induction of nitric oxide (no) production by macrophages. we observed that kp has no direct inhibitory activity on extracellular promastigotes, but effectively decreases the intracellular amastigote growth in a dose-re ... | 1999 | 10406036 |
| leishmania amazonensis infection induces changes in the electrophysiological properties of macrophage-like cells. | whole cell patch-clamp recordings were used to study the electrical properties of the macrophage-like cell line j774.1, after infection with leishmania amazonensis. infection induced a significant increase in cell size and membrane capacitance, suggesting that parasite invasion leads to the addition of plasma membrane to the host cell. by 24 hr after infection, the host cell membrane potential was significantly more hyperpolarized than control cells, and this difference remained for the subseque ... | 1999 | 10430661 |
| comparison of different staining procedures for the flow cytometric analysis of u-937 cells infected with different leishmania-species. | the human macrophage cell line u-937 infected with different leishmania species, leishmania mexicana amazonensis (lma), leishmania donovani (ld) and leishmania infantum (li), was analyzed by flow cytometry (fcm). leishmania spp. were labeled with different stains prior to the infection of the u-937 cells (bcecf-am, pkh2-gl and syto 17) or after the infection (ao, fitc-conjugated monoclonal antibodies, pi). infected cells were analyzed by flow cytometry, fluorescence microscopy and in parallel mi ... | 1999 | 10445312 |
| a dhfr-ts- leishmania major knockout mutant cross-protects against leishmania amazonensis. | e10-5a3 is a dhfr-ts- leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent l. major infection in both genetically susceptible and resistant mice. we investigated the capacity of dhfr-ts- to protect against heterologous infection by l. amazonensis. the degree of protection was evaluated by immunization of balb/c or c57bl/6 mice with e10-5a3, followed by l. amazonensis challenge. whether immunized by subcutaneous (sc) or intravenous (iv) i ... | 1999 | 10446007 |
| short report: evaluation of the potency and stability of a candidate vaccine against american cutaneous leishmaniasis. | availability of a safe, immunogenic, and affordable vaccine would represent the best strategy for control of cutaneous leishmaniasis (cl). stability in field conditions is a essential property for any candidate vaccine. the stability and immunogenicity of three different preparations (thimerosal-preserved, autoclaved, and lyophilized) of a killed leishmania amazonensis vaccine were assessed using fresh products and after 12 months of storage at 4 degrees c. autoclaving was associated with a time ... | 1999 | 10463682 |
| antisense effects of oligonucleotides complementary to the hairpin of the leishmania mini-exon rna. | we investigated the binding and the translation inhibitory properties of hexadecamers complementary to the mini-exon sequence of the protozoan parasite leishmania amazonensis. this targeted rna region folds into a hairpin. large differences were observed in the antisense properties of the different oligomers although their binding to rna always requires the disruption of the stem region. | 1999 | 10474250 |
| altered tyrosine phosphorylation of erk1 map kinase and other macrophage molecules caused by leishmania amastigotes. | the involvement of tyrosine phosphorylation during macrophage infection with leishmania amazonensis amastigotes was investigated. ptk antagonists such as genistein, herbimycin a, geldanamycin and tyrphostin 25 had no significant effect on adhesion to, or entry into, murine peritoneal macrophages, but increased parasite intracellular survival. lps-induced tyrosine phosphorylation of target host proteins assessed by immunoprecipitation and western blot was impaired or reversed by living amastigote ... | 1999 | 10477171 |
| construction of chimeric phagosomes that shelter mycobacterium avium and coxiella burnetii (phase ii) in doubly infected mouse macrophages: an ultrastructural study. | dual infection of cells may divert pathogens to intracellular compartments different from those occupied in mono-infected cells. in the present studies, mouse bone marrow in vitro-derived macrophages were first infected with virulent mycobacterium avium, which are normally singly lodged within tight phagosomes. these phagosomes do not mature; they undergo homotypic fusion with early endosomes and do not fuse with lysosomes. seven days later, the cultures were superinfected with phase ii (non-vir ... | 1999 | 10494865 |
| expression and cellular localization of ribonucleotide reductase small subunit m2 protein in hydroxyurea-resistant leishmania mexicana amazonensis. | we raised a specific antiserum against the recombinant m2 subunit protein of ribonucleotide reductase of leishmania mexicana amazonensis in rabbit. this antiserum was used to study the expression and cellular location of the m2 protein in wildtype as well as hydroxyurea-resistant variants (hur) of the parasite. the protein increased with increasing dose of the drug used for selection of resistance. the increase in protein level was accompanied by an increase in the copy numbers of mrna of the m2 ... | 1999 | 10498182 |
| protective immunity using recombinant human il-12 and alum as adjuvants in a primate model of cutaneous leishmaniasis. | protection from cutaneous leishmaniasis, a chronic ulcerating skin lesion affecting millions, has been achieved historically using live virulent preparations of the parasite. killed or recombinant ags that could be safer as vaccines generally require an adjuvant for induction of a strong th1 response in murine models. murine ril-12 as an adjuvant with soluble leishmania ag has been shown to protect susceptible mice. we used 48 rhesus macaques to assess the safety, immunogenicity, and efficacy of ... | 1999 | 10510390 |
| persistence of leishmania antigen in c57bl/6j inbred mice infected with leishmania (leishmania) amazonensis. | to develop an animal model for studying mucocutaneous leishmaniasis. | 1999 | 10513053 |
| protection of c57bl/10 mice by vaccination with association of purified proteins from leishmania (leishmania) amazonensis. | in the past few years, induction of protective immunity to cutaneous leishmaniasis has been attempted by many researchers using a variety of antigenic preparations, such as living promastigotes or promastigote extracts, partially purified, or defined proteins. in this study, eleven proteins from leishmania (leishmania) amazonensis (lla) with estimated molecular mass ranging from 97 to 13.5kda were isolated by polyacrylamide gel electrophoresis and electro-elution. the proteins were associated as ... | 1999 | 10564919 |
| efficacy of the triazole sch 56592 against leishmania amazonensis and leishmania donovani in experimental murine cutaneous and visceral leishmaniases. | current therapy for leishmaniasis is unsatisfactory. efficacious and safe oral therapy would be ideal. we examined the efficacy of sch 56592, an investigational triazole antifungal agent, against cutaneous infection with leishmania amazonensis and visceral infection with leishmania donovani in balb/c mice. mice were infected in the ear pinna and tail with l. amazonensis promastigotes and were treated with oral sch 56592 or intraperitoneal amphotericin b for 21 days. at doses of 60 and 30 mg/kg/d ... | 1999 | 10582881 |
| non-ulcerative cutaneous lesion in immunodeficient mice with leishmania amazonensis infection. | cutaneous leishmaniasis begins as papules or nodules at the site of promastigote inoculation. the next key pathogenic event in this disease is the formation of an ulcer at this site. leishmania infection in immunodeficient mice, however, showed non-ulcerative cutaneous lesions suggesting the involvement of the immune system in ulcer formation. severe combined immunodeficient (scid), recombination-activating gene 2 knockout (rag-2-/-), and immunocompetent mice were inoculated subcutaneously with ... | 1999 | 11269325 |
| structural and functional analysis of the lamdr1 multidrug resistance gene in leishmania amazonensis. | we determined primary sequences of the lamdr1 gene in leishmania amazonensis, a protozoan parasite that causes cutaneous leishmaniasis. the longest open reading frame encodes 1341 amino acids for a protein consisting of two similar halves, each containing six putative transmembrane domains and one atp-binding domain. the protein has no potential n-glycosylation sites at the extracellular region. the lamdr1 protein was 91 and 78% identical to the closely related ldmdr1 in l. donovani and lemdr1 i ... | 1999 | 10049701 |
| improvement of in vitro and in vivo antileishmanial activities of 2', 6'-dihydroxy-4'-methoxychalcone by entrapment in poly(d,l-lactide) nanoparticles. | the inhibition of intracellular leishmania amazonensis growth by 2', 6'-dihydroxy-4'-methoxychalcone (dmc) isolated from piper aduncum was further enhanced after encapsulation of dmc in polymeric nanoparticles. encapsulated dmc also showed increased antileishmanial activity in infected balb/c mice, as evidenced by significantly smaller lesions and fewer parasites in the lesions. | 1999 | 10390243 |
| leishmania amazonensis: the phagocytosis of amastigotes by macrophages. | in the present study, we examine the cell biology of leishmania amastigote uptake by mammalian cells and compare this process to the phagocytosis of igg-opsonized erythrocytes. we report that many aspects of amastigote uptake into macrophages resemble classical receptor-mediated phagocytosis. parasite uptake requires energy expenditure by macrophages but not by parasites. treating macrophages to prevent either energy metabolism or actin polymerization prevents amastigote uptake. the uptake of am ... | 1998 | 9562419 |
| leishmania amazonensis: long-term cultivation of axenic amastigotes is associated to metacyclogenesis of promastigotes. | axenic leishmania amazonensis cultures were obtained (with 2 years of follow-up) in schneider's medium at ph 5.5 and a temperature of 32 degrees c. differentiation of promastigotes into amastigotes is directly associated with the metacyclogenesis rate of the original promastigotes. promastigote cultures containing different percentages of metacyclic forms, as evaluated by the complement lysis test, resulted in axenic amastigote cultures containing a variable amount of undifferentiated forms. we ... | 1998 | 9603489 |
| partially glucose-capped oligosaccharides are found on the hemoglobins of the deep-sea tube worm riftia pachyptila. | we report here the structural determination of n-linked oligosaccharides found on extracellular hemoglobins of the hydrothermal vent tube worm riftia pachyptila. structures were elucidated by a combination of electrospray ionization tandem mass spectrometry, matrix-assisted laser desorption/ionization mass spectrometry, normal-phase high performance liquid chromatography, and exoglycosidase digestion. the sugar chains were found to consist mainly of high-mannose-type glycans with some structures ... | 1998 | 9621107 |
| genus-specific expression from the sl rna promoter of leishmania amazonensis. | 1998 | 9635452 | |
| in vitro method for isolation of amastigote forms of leishmania amazonensis from j774g8 macrophage induced by temperature shifting. | 1998 | 9698849 | |
| phase 1 study of an inactivated vaccine against american tegumentary leishmaniasis in normal volunteers in brazil. | a phase 1 double-blind placebo-controlled study was performed to evaluate a vaccine against american tegumentary leishmaniasis in 61 healthy male volunteers. side effects and the immune response to the vaccine were evaluated, with 1- and 2- dose schemes, with intervals of 7 or 21 days, each dose containing 1440 mg of protein n antigen of a single strain of leishmania amazonensis (ph8) diluted in merthiolated saline (1:10,000). merthiolated saline and an inert substance were used as placebos. no ... | 1998 | 9698895 |
| leishmania amazonensis infection is reduced in macrophages treated with guanine ribonucleosides. | 1998 | 9707370 | |
| susceptibility and resistance to leishmania amazonensis in h-2q syngeneic high and low antibody responder mice (biozzi mice). | h-2 syngeneic h and l (biozzi) mice provide a model to study leishmania infections in which polar resistant and susceptible phenotypes are independent from h-2 differences. high-ab-responder (h) and low-ab-responder (l) mice syngeneic at the h-2 locus (h-2q) were, respectively, susceptible and highly resistant to leishmania amazonensis infection. l-mice resistance was associated with high ifn-gamma and transient il-4 production by lymph node (ln) cells, in contrast with sustained il-4 and decrea ... | 1998 | 9716105 |
| efficacies of ky62 against leishmania amazonensis and leishmania donovani in experimental murine cutaneous leishmaniasis and visceral leishmaniasis. | current therapy for leishmaniasis is unsatisfactory because parenteral antimonial salts and pentamidine are associated with significant toxicity and failure rates. we examined the efficacy of ky62, a new, water-soluble, polyene antifungal, against cutaneous infection with leishmania amazonensis and against visceral infection with leishmania donovani in susceptible balb/c mice. mice were infected with l. amazonensis promastigotes in the ear pinna and in the tail and were treated with ky62 or amph ... | 1998 | 9756753 |
| a new focus of cutaneous leishmaniasis due to leishmania amazonensis in a sub andean region of bolivia. | we detected a new outbreak focus with high incidence of cutaneous leishmaniasis in the sub andean region of la paz. this area was never considered previously as an endemic zone of leishmaniasis. leishmania stocks from human lesions were isolated: three stocks were explored by pulse field gradient electrophoresis, showing evidence for their affiliation to the l. mexicana complex. eight stocks were submitted to isoenzyme electrophoresis and compared with five reference strains: l. amazonensis, l. ... | 1998 | 9821459 |
| cloning and functional expression of the human glcnac-1-p transferase, the enzyme for the committed step of the dolichol cycle, by heterologous complementation in saccharomyces cerevisiae. | the gene for the human dolichol cycle glcnac-1-p transferase (alg7/gpt) was cloned by screening a human lung fibroblast cdna library. the library was constructed in a saccharomyces cerevisiae expression vector, and the positive clone was identified by complementation of the conditional lethal s.cerevisiae strain yph-a7-gal. this strain was constructed by replacing the endogenous promoter of the gpt-gene by the stringently regulated gal1-promoter. this construct allows to specifically suppress th ... | 1998 | 9451016 |
| in vivo formation of electron paramagnetic resonance-detectable nitric oxide and of nitrotyrosine is not impaired during murine leishmaniasis. | recent studies have provided evidence for a dual role of nitric oxide (no) during murine leishmaniasis. to explore this problem, we monitored the formation of no and its derived oxidants during the course of leishmania amazonensis infection in tissues of susceptible (balb/c) and relatively resistant (c57bl/6) mice. no production was detected directly by low-temperature electron paramagnetic resonance spectra of animal tissues. both mouse strains presented detectable levels of hemoglobin nitrosyl ... | 1998 | 9453645 |
| leishmania (leishmania) amazonensis: purification and enzymatic characterization of a soluble serine oligopeptidase from promastigotes. | a soluble proteinase was purified 90-fold from extracts of promastigotes of leishmania (leishmania) amazonensis using a combination of ion-exchange chromatography in q-sepharose fast flow, gel filtration chromatography in sephacryl hr s-200, and chromatofocusing. the enzyme appeared as a single band with an apparent molecular weight of 101 kda by silver staining following sds-page, under both reducing and nonreducing conditions. the proteinase has a ph optimum between 8.0 and 8.5 and an isoelect ... | 1998 | 9635438 |
| intracellular leishmania amazonensis killing induced by the guanine nucleoside 8-bromoguanosine. | in this study we investigated the effect of 8-bromoguanosine, an immunostimulatory compound, on the cytotoxicity of macrophages against leishmania amazonensis in an in vitro system. the results showed that macrophages treated with 8-bromoguanosine before or after infection are capable to reduce parasite load, as monitored by the number of amastigotes per macrophage and the percentage of infected cells (i.e. phagocytic index). since 8-bromoguanosine was not directly toxic to the promastigotes, it ... | 1998 | 9876437 |
| leishmania sp.: growth and survival are impaired by ion channel blockers. | in the present work we examined the effect of ion transport blockers on the growth and viability of leishmania sp. and on the infection of macrophages by the parasite. 4-aminopyridine and glibenclamide block voltage-dependent and k+ atp channels, respectively; amiloride is used to detect na+ channels and na+/h+ antiporters; and anthracene-9-carboxylic acid affects chloride channels. the ec50 for promastigote cultures of three strains of the leishmania subgenus, namely, leishmania (leishmania) nr ... | 1998 | 9501844 |
| the potential effects of new synthetic drugs against leishmania amazonensis and trypanosoma cruzi. | amidine derivatives, never used before on trypanosomatids, were tested against leishmania amazonensis and trypanosoma cruzi. these drugs in doses up to 500 mg/kg inoculated into swiss mice did not show any toxic effect (santos, 1993). the in vitro effect of n,n'-diphenyl-4-r- benzamidine was evaluated. l. amazonensis promastigotes, epimastigotes and blood forms of t. cruzi, were assayed with/without the drugs in axenic media, using pentamidine isethionate and benznidazole, as reference drugs. th ... | 1997 | 9301071 |
| stage-independent splicing of transcripts two heterogeneous neighboring genes in leishmania amazonensis. | gene expression in trypanosomatid protozoa is largely regulated posttranscriptionally, e.g., 5' splice leader addition and 3' polyadenylation of mrnas. we examined these events in leishmania by mapping the splice sites of the transcripts from two different, but closely linked single-copy genes 2.3 kb apart. the coding regions of the approx. 1 kb upstream gene (p36) and the approx. 1.4 kb downstream gene (nagt) produce approx. 2 and 3 kb mrnas, respectively. both genes were overexpressed in cells ... | 1997 | 9322740 |
| experimental treatment of cutaneous leishmaniasis with argentilactone isolated from annona haematantha. | from the hexanic extract of roots of annona haematantha an alpha,beta-unsaturated delta-lactone was isolated and identified as argentilactone. this compound exhibited in vitro activity against various strains of leishmania ssp. at 10 micrograms/ml. balb/c mice infected with leishmania amazonensis were treated four weeks after infection with argentilactone by oral or subcutaneous routes for 14 days at 25 mg/kg daily. the reference drug, n-methylglucamine antimonate, was administered by subcutaneo ... | 1997 | 9342948 |
| experimental cutaneous leishmaniasis: transmission electron microscopy of the inoculation site. | tissue response against inoculation of leishmania (leishmania) amazonensis promastigotes in the hind footpad was quite different between two strains of mice: in balb/c animals there was parasitism of perineurial cells by the 8th week post inoculation (wpi) and heavy parasitism of macrophages, as well as degenerated extracellular parasites close to collagen fibers at the 39th wpi, whereas in c57bi/6j mice there was heavy parasitism of macrophages at 6th wpi, dermal vessels with high endothelial c ... | 1997 | 9203982 |
| pore-forming proteins in pathogenic protozoan parasites. | pore-forming proteins (pfps) may play important roles in pathogenesis by protozoan parasites by either directly damaging the plasma membrane of the host cells or ensuring intracellular survival of the parasites by promoting their exit from lysosomal vacuoles. the leishmania amazonensis pore-forming cytolysin, leishporin, may play a crucial role in the pathogenesis of leishmaniasis. | 1997 | 9294893 |
| scavenger receptor-mediated delivery of antisense mini-exon phosphorothioate oligonucleotide to leishmania-infected macrophages. selective and efficient elimination of the parasite. | targeted delivery of a 17-mer antisense phosphorothioate oligodeoxyribonucleotide, complementary to the common 5'-end of every mrna of the parasite cells, to the phagolysosomes of cultured murine macrophages infected with leishmania mexicana amazonensis selectively and efficiently eliminated the parasite cells without causing any detectable harm to the host cells. the antisense mini-exon oligonucleotide (asm) was encapsulated into liposomes coated with maleylated bovine serum albumin (mbsa), the ... | 1997 | 9065742 |
| homologues of the 24-kda flagellar ca(2+)-binding protein gene of trypanosoma cruzi are present in other members of the trypanosomatidae family. | a full-length cdna encoding the 24-kda flagellar ca(2+)-binding protein (fcabp) of the dm28c clone of trypanosoma cruzi was cloned and characterized. comparison of the deduced amino acid sequence with those of the fcabps of other t. cruzi strains revealed greater than 97% sequence conservation. fcabp-like genes are found in trypanosoma conorhini, trypanosoma freitasi, trypanosoma lewisi, herpetomonas megaseliae, leptomonas seymouri, and phytomonas serpens, but not in crithidia deanei, leishmania ... | 1997 | 9225770 |
| presentation via the class i pathway by leishmania amazonensis-infected macrophages of an endogenous leishmanial antigen to cd8+ t cells. | cd8+ t cells play a protective role in immunity to cutaneous leishmaniasis. however, it has been unclear how these cells execute this function, since results from several investigations attempting to demonstrate recognition of leishmania-infected macrophages by cd8+ t cells have been contradictory. in this study, we report the generation of cd8+ t cell lines specific for gp46/m-2, a leishmanial ag, previously shown to protectively immunize mice against a leishmania amazonensis challenge. using t ... | 1997 | 9257846 |
| immune response and protection in mice inoculated with leishmania amazonensis clones expressing different degrees of virulence. | the induction of protective immunity to leishmania amazonensis was investigated by injection of parasite clones of low and medium virulence into susceptible mice. to this end, l. amazonensis were cloned by limiting dilution and the clones' virulence was evaluated by the course of infection in susceptible mice. clones originally derived from the spleen showed virulence variations in comparison with that of the parental population (pp) of parasites. two low-virulence clones (sp 5 and sp 20) and on ... | 1997 | 9272560 |
| identification of a transcription factor like protein at the tor locus in leishmania mexicana amazonensis. | the tor gene (toxic nucleoside resistance gene) was mapped to a 2.3 kb fragment on the amplified dna from tubercidin resistant leishmania (tub). this dna fragment conferred upon wild type cells resistance to tubercidin, inosine dialdehyde, formycin a and b and allopurinol riboside and a reduced ability to accumulate purine nucleobases and nucleosides. these properties were characteristic of the parental tub cells which carried the intact amplified dna and have been hypothesized to be caused by a ... | 1997 | 9476797 |
| leishmania amazonensis promastigotes evade complement killing by interfering with the late steps of the cascade. | during their growth in vitro, promastigotes of leishmania amazonensis undergo differentiation from complement-susceptible to complement-resistant forms. here, we demonstrate that both forms bind comparable amounts of c3 on their surfaces, with the predominant molecule species being the haemolytically active c3b. likewise, equivalent amounts of c9 are deposited on both forms of promastigotes. however, while c9-bearing complexes are exposed on the cell surface of resistant promastigotes, they are ... | 1997 | 9488871 |
| experimental cutaneous leishmaniasis. iv. the humoral response of cebus apella (primates: cebidae) to infections of leishmania (leishmania) amazonensis, l. (viannia) lainsoni and l. (v.) braziliensis using the direct agglutination test. | the direct agglutination test (dat) was used to evaluate the serological response of 150 serum samples taken from 15 captive-bred capuchin monkeys cebus apella. these animals had been experimentally infected with either l. (leishmania) amazonensis, l. (viannia) lainsoni or l. (v.) braziliensis. monkeys infected with l. (l.) amazonensis or l. (v.) lainsoni were challenged with the homologous parasite one month after their spontaneous cure. dat antigens were prepared from l. (l.) donovani, l. (l.) ... | 1997 | 9352003 |
| leishmania braziliensis, molecular characterization of an elongation factor 1alpha gene. | the elongation factor ef-1alpha is one of the most studied components of the translation machinery owing to its abundance and possible role in other cellular functions. ef-1alpha mediates the correct coupling of the aminoacyl-trna on the a site of the ribosome in a gtp-dependent reaction. we have previously described an ef-1alpha dna sequence in leishmania amazonensis, plef11 (accession no. m92653), using pcr. in this paper we describe the dna sequence and genomic organization of l. braziliensis ... | 1997 | 9370293 |
| parasite-driven in vitro human lymphocyte cytotoxicity against autologous infected macrophages from mucosal leishmaniasis. | parasite-specific cytotoxicity in human leishmaniasis was evaluated in an autologous system. pbl from cutaneous leishmaniasis (cl) or mucosal leishmaniasis (ml) patients were exposed to leishmania amazonensis-infected autologous macrophages for 7 days and then used as effector cells in a cytotoxic assay using 51cr-labeled autologous infected macrophages as targets. results are reported as lu per 10(7) pbmc. cytotoxic activity is present in ml (9.7 +/- 2.1 lu/10(7) pbmc) but not in cl (1.5 +/- 2. ... | 1997 | 9379046 |
| in vitro maintenance of leishmania amastigotes directly from lesions: advantages and limitations. | leishmania amazonensis (mhom/br/77/ltb0016) amastigotes were obtained from mouse cutaneous lesions and maintained in vitro for 48 hr at ph 4.6, 33 c. these organisms were reproducing, capable of transformation to promastigotes, and did not display the promastigote-specific antigen, gp46. in contrast, 97% of the organisms maintained for 24 hr at 31 c, ph 7.3, were positive for gp46. thus, short-term cultivation of this l. amazonensis strain under appropriate conditions can provide a high yield of ... | 1997 | 9379307 |
| association of leishmania heat shock protein 83 antigen and immunoglobulin g4 antibody titers in brazilian patients with diffuse cutaneous leishmaniasis. | diffuse cutaneous leishmaniasis (dcl) is characterized by the presence of numerous nonulcerated nodules and plaques containing large numbers of leishmania amazonensis parasites and few lymphoid elements. the immune responses of dcl patients reflect severe antigen-specific t-cell deficiencies, while the antibody response to leishmania antigens is often accentuated. we report herein on the leishmania antigen-specific antibody subclass distribution in dcl patients and demonstrate that a dominant an ... | 1997 | 9393843 |
| immune responses induced by a leishmania (leishmania) amazonensis recombinant antigen in mice and lymphocytes from vaccinated subjects. | in the search for leishmania recombinant antigens that can be used as a vaccine against american cutaneous leishmaniasis, we identified a leishmania (leishmania) amazonensis recombinant protein of 33 kd (larp33) which is recognized by antibodies and peripheral blood leukocytes (pbl) from subjects vaccinated with leishvacin, larp33 was expressed in escherichia coli after cloning of a 2.2 kb sau3 digested genomic fragment of l. (l.) amazonensis into the pds56-6 his vector. immunoblotting analysis ... | 1997 | 9394518 |
| activity of compounds isolated from chilean lichens against experimental cutaneous leishmaniasis. | three secondary metabolites isolated from chilean lichens, (+) usnic acid, pannarine and 1'-chloropannarine, were tested against promastigotes forms of three strains of leishmania ssp. pannarine and 1'-chloropannarine exhibited in vitro activity at 50 micrograms/ml and (+) usnic acid at 25 micrograms/ml. balb/c mice infected with leishmania amazonensis were treated 4 weeks post-infection with (+) usnic acid by subcutaneous or oral routes for 15 days at 25 mg/kg or by five intralesional injection ... | 1997 | 9080673 |
| intracellular ca2+ pool content and signaling and expression of a calcium pump are linked to virulence in leishmania mexicana amazonesis amastigotes. | virulent and avirulent clones of leishmania mexicana amazonensis promastigotes or amastigotes were loaded with the fluorescent reagent fura 2/am to measure intracellular free calcium ([ca2+]i). when the cells were treated with the calcium ionophore ionomycin in the nominal absence of extracellular ca2+, there was an increase of [ca2+]i that was further elevated by addition of either nh4cl, nigericin, or the vacuolar h+-atpase inhibitor bafilomycin a1. similar results were obtained when the order ... | 1997 | 9083086 |
| effects of pentamidine on polyamine level and biosynthesis in wild-type, pentamidine-treated, and pentamidine-resistant leishmania. | polyamine biosynthesis was studied in wild-type promastigotes of leishmania donovani and leishmania amazonensis treated with pentamidine and in the parasites resistant to this drug. treatment of wild-type clones with low pentamidine concentrations for 24 hr provoked a strong decrease in arginine, ornithine, and putrescine pools, while the level of intracellular spermidine remained unchanged. in these cells, the activity of the enzyme ornithine decarboxylase was found to be decreased. compared to ... | 1997 | 9085924 |
| effect of protein kinase inhibitors on the growth, morphology, and infectivity of leishmania promastigotes. | the effect of two protein kinase inhibitors, staurosporine and h-7, on the growth, morphology and infectivity of leishmania major and leishmania amazonensis promastigotes was examined. incubation with h-7 (600 microm) for up to one hour had no effect on parasite growth, morphology or infectivity. staurosporine, however, was cytotoxic for promastigotes and incubation for 1, 5 or 15 minutes with 10 microm inhibitor killed 19, 34 and 59%, respectively, of the parasites. longer incubations, up to on ... | 1997 | 9089725 |
| use of an enzymatic micromethod to quantify amastigote stage of leishmania amazonensis in vitro. | 1997 | 9134568 | |
| axenically cultured amastigote forms as an in vitro model for investigation of antileishmanial agents. | using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide microassay, previously described as a means of quantifying leishmania amazonensis in vitro at the amastigote stage (d. sereno and j. l. lemesre, parisitol. res., in press), we have compared the activities of seven drugs, including those currently used to treat leishmaniasis, against axenically grown amastigote and promastigote forms of three leishmania species (l. amazonensis, l. mexicana, and l. infantum, responsible for diffu ... | 1997 | 9145854 |
| cloning and functional analysis of the ribonucleotide reductase gene small subunit from hydroxyurea-resistant leishmania mexicana amazonensis. | 1997 | 9497060 | |
| role of cd4+ t cells in pathogenesis associated with leishmania amazonensis infection. | most inbred strains of mice are susceptible to leishmania amazonensis infection. we have examined the mechanism(s) underlying this generalized susceptibility using mice deficient in t cell development or in the expression of either mhc class i or class ii. in contrast to wild-type c57bl/6 (b6) mice that uniformly developed large ulcerating lesions, mice lacking functional cd4+ t cells (due to targeted disruption of genes for either mhc class ii trans-activator or i-a beta) showed no signs of les ... | 1997 | 9164958 |
| characterization of an antigen from leishmania amazonensis amastigotes able to elicit protective responses in a murine model. | lymphoproliferative responses to an antigen from leishmania amazonensis amastigotes with an apparent molecular mass of 30 kda, termed p30, were evaluated with balb/c mice. the p30 antigen was purified after separation of parasite extracts by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by electroelution. lymphoproliferative responses to p30 were obtained by subcutaneous immunization of animals with l. amazonensis amastigote extracts, and maximal stimulation indices were obs ... | 1997 | 9169731 |
| fusion of leishmania amazonensis parasitophorous vacuoles with phagosomes containing zymosan particles: cinemicrographic and ultrastructural observations. | studies on fixed preparations have shown that vacuoles containing zymosan (z) particles internalized by infected macrophages can selectively fuse with the large parasitophorous vacuoles (pvs) that shelter leishmania amazonensis. to examine the kinetics of vacuolar fusion in individual cells, particles were followed by time-lapse cinemicrography from their uptake to their entry in a pv. newly formed z-containing vacuoles moved centripetally and, if they contacted a pv, the two vacuoles remained c ... | 1996 | 9181083 |
| heat shock induction of apoptosis in promastigotes of the unicellular organism leishmania (leishmania) amazonensis. | apoptosis and/or programmed cell death have been described in examples ranging from fungi to man as gene-regulated processes with roles in cell and tissue physiopathology. these processes require the operation of an intercellular communicating network able to deliver alternative signals for cells with different fates and is thus considered a prerogative of multicellular organisms. promastigotes from leishmania (leishmania) amazonensis, when shifted from their optimal in vitro growth temperature ... | 1996 | 8613472 |
| pentamidine uptake in leishmania donovani and leishmania amazonensis promastigotes and axenic amastigotes. | a transport system for pentamidine in leishmania donovani and leishmania amazonensis promastigotes and axenic amastigotes has been identified and characterized. pentamidine is not metabolized by these parasites. its uptake process is saturable, carrier-mediated and energy-dependent. this drug does not inhibit purine or pyrimidine uptake, whereas it inhibits uptake of several amino acids non-competitively and that of putrescine and spermidine competitively. the results suggest that pentamidine sh ... | 1996 | 8615840 |
| leishmania amazonensis: the asian rhesus macaques (macaca mulatta) as an experimental model for study of cutaneous leishmaniasis. | as a means of assessing the usefulness of the rhesus macaque (macaca mulatta) as a nonhuman primate model for studying cutaneous leishmaniasis, monkeys were infected with leishmania amazonensis. variation in the level of susceptibility was found; however, animals inoculated with 10(8) promastigotes provided consistent results as indicated by an earlier onset and/or larger size of lesions. three monkeys, which had recovered from skin lesions, were challenge-infected using the same parasite strain ... | 1996 | 8617329 |
| in vivo efficacy of oral and intralesional administration of 2-substituted quinolines in experimental treatment of new world cutaneous leishmaniasis caused by leishmania amazonensis. | the antileishmanial efficacies of 2-n-propylquinoline, chimanines b and d, 2-n-pentylquinoline, 2-phenylquinoline, 2-(3,4-methylenedioxyphenylethyl) quinoline, and two total alkaloidal extracts of galipea longiflora were evaluated in balb/c mice infected with leishmania amazonensis or leishmania venezuelensis. animals were treated for 4 to 6 weeks postinfection with a quinoline by the oral route at 50 mg/kg of body weight twice daily for 15 days or by five intralesional injections at intervals o ... | 1996 | 8913444 |
| structural and functional characterization of the leishmania amazonensis ribosomal rna promoter. | the promoter region of the ribosomal rna (rrna) genes of leishmania amazonensis was characterised and the transcription start point, defined by primer extension, was shown to be a t residue, 1048 nucleotides upstream of the beginning of the 18s sequence. a repetitive element of 60 bp was identified in the intergenic spacer. this element did not show sequence similarity with the region around the transcription start point. conserved sequences were found in the external transcribed spacer of l. am ... | 1996 | 8920010 |
| cytolytic activity in the genus leishmania: involvement of a putative pore-forming protein. | we describe here that parasites of the genus leishmania contain a cytolytic activity which acts optimally at ph 5.0 to 5.5 and at 37 degrees c in vitro. or the four species examined, leishmania (leishmania) amazonensis and leishmania (leishmania) major presented considerable hemolytic activity, whereas leishmania (viannia) panamensis and leishmania (viannia) guyanensis showed little and no hemolytic activity, respectively. the cytolytic factor of l. amazonensis promastigotes was characterized as ... | 1996 | 8926057 |
| surface zn-proteinase as a molecule for defense of leishmania mexicana amazonensis promastigotes against cytolysis inside macrophage phagolysosomes. | the role of the surface membrane zn-proteinase in protecting the cellular integrity of the macrophage parasite leishmania mexicana amazonensis from intraphagolysosomal cytolysis was studied. these cells lose their infectivity to host macrophages after prolonged cultivation in axenic growth medium. the virulent and attenuated variants of the parasite cells were cloned. failure of these attenuated parasite cells to survive inside macrophage phagolysosomes is associated with 20- to 50-fold reductio ... | 1996 | 8945556 |
| identification of n-acetylspermidine in leishmania amazonensis. | 1996 | 8992324 | |
| formation of nitrosyl hemoglobin and nitrotyrosine during murine leishmaniasis. | peroxynitrite, the potent oxidant formed by the fast reaction between nitric oxide and superoxide anion, has been suggested to be the reactive intermediate responsible for some of the pathologies associated with an over-production of nitric oxide. in this report, we demonstrate that both nitric oxide and peroxynitrite are formed during infection of the susceptible mouse strain, balb/c, with leishmania amazonensis. nitric oxide was detected as the nitrosyl hemoglobin complex by epr analysis of bl ... | 1996 | 8992499 |
| biological behavior of leishmania amazonensis isolated from humans with cutaneous, mucosal, or visceral leishmaniasis in balb/c mice. | leishmania amazonensis causes a wide spectrum of disease in humans. in this study, we evaluated balb/c mice infected with five strains of l. amazonensis isolated from patients with either cutaneous, mucosal, or visceral leishmaniasis. mice infected with cutaneous and mucosal isolates developed ulcerating footpad lesions with parasite-loaded macrophages and extensive tissue destruction. skin metastases, early dissemination of parasites to the spleen, and high anti-leishmania antibody levels were ... | 1996 | 8619444 |
| disruption of cd40-cd40 ligand interactions results in an enhanced susceptibility to leishmania amazonensis infection. | to study the role of cd40 ligand (cd40l) in the host immune responses against intracellular pathogens, we infected cd40l knockout (cd40l-/-) mice with leishmania amazonensis. although wild-type mice were susceptible to infection and developed progressive ulcerative lesions, tissue parasite burdens in cd40l-/- mice were significantly higher. this heightened susceptibility to infection was associated with an impaired t cell and macrophage activation and altered inflammatory response, as reflected ... | 1996 | 8624816 |
| glycosidases in leishmania and their importance for leishmania in phlebotomine sandflies with special reference to purification and characterization of a sucrase. | culture forms of leishmania (leishmania) amazonensis (ifla/br/67/ph8) produce an extracellular enzyme that hydrolyzes sucrose molecules into their component monosaccharides. this is important because phlebotomine sand flies, the invertebrate hosts of leishmania, ingest plant sap or aphid and coccid honeydew rich in sucrose between blood meals and leishmania promastigotes cannot uptake sucrose. the sucrase was purified and characterized; its molecular weight, estimated by gel filtration chromatog ... | 1996 | 8654540 |
| leishmania amazonensis: cultivation and characterization of axenic amastigote-like organisms. | extracellular amastigote-like forms of leishmania amazonensis can be maintained in axenic culture at 32 degrees c, ph 4.6, with a generation time of approximately 17 hr. this species of leishmania is of particular interest since it has been associated with cutaneous, diffuse cutaneous, and mucocutaneous forms of the disease. immunofluorescence, western and northern blot analyses, and immunoprecipitation have been used to estimate the expression levels of amastigote or promastigote antigens in ax ... | 1996 | 8654556 |
| in vivo protective effect of the lectin from canavalia brasiliensis on balb/c mice infected by leishmania amazonensis. | in vivo administration of canavalia brasiliensis lectin (at the time of infection, or maintained throughout the infection) reduced the lesions of highly susceptible balb/c mice infected by leishmania amazonensis. at the doses used c. brasiliensis lectin (conbr) does not interfere with penetration or fate of leishmania in the macrophages in vitro. since interferon-gamma (ifn-gamma) is the major macrophage activating factor, and considered a critical element in the successful immune response again ... | 1996 | 8659323 |
| cohabitation of leishmania amazonensis and coxiella burnetii. | intracellular pathogens customize the composition and function of the vacuoles they occupy, and can arrest or distort vacuolar maturation. in doubly infected cells, vacuoles that contain two different parasites can be used to test for exclusionary mechanisms, for expression of vacuolar phenotypes that permit or restrict fusion, and for the survival of pathogens targeted to an unusual cellular compartment. | 1996 | 8728610 |
| polyamine n-acetyltransferase in leishmania amazonensis. | n-acetyltransferase, which is suggested to be responsible for the production of n1-acetylspermidine in leishmania amazonensis and to be involved in the process of inactivation and degradation of excessive polyamines, was partially purified and characterized. among the substrates tested, sym-norspermidine, sym-norspermine, and 1,3-diaminopropane had the highest reaction rates, but the naturally occurring polyamines spermine and spermidine were also acetylated at considerable rates, whereas putres ... | 1996 | 8738283 |
| [a canine survey in a recent focus of cutaneous leishmaniasis in the city of sabará, the metropolitan area of belo horizonte]. | in 1992, a dog naturally infected with leishmania was found in a periurban area of sabará, state of minas gerais, where human cutaneous leishmaniasis had been previously described. the parasite was classified as leishmania, subgenus viannia, which l. braziliensis, the main species of parasite present in the southeast brazil, also belongs. in order to assess the importance of the dog in the transmission cycle of the disease, a canine survey was undertaken. six hundred thirty-one dogs were examine ... | 1996 | 8768580 |
| determination of receptor-bound drug conformations by qsar using flexible fitting to derive a molecular similarity index. | results are presented for a qsar analysis of bisamidines, using a similarity index as descriptor. the method allows for differences in conformation of bisamidines at the receptor site to be taken into consideration. in particular, it has been suggested by others that pentamidine binds in the minor groove of dna in a so-called isohelical conformation, and our qsar supports this suggestion. the molecular similarity index for comparison of molecules can be used as a parameter for correlating and he ... | 1996 | 8786416 |
| double hairpin complexes allow accommodation of all four base pairs in triple helices containing both dna and rna strands. | we investigated the binding of an antisense oligodeoxynucleotide to a stem-loop structure corresponding to the mini-exon sequence of the protozoan parasite leishmania amazonensis. this oligomer was designed to anneal to the single-stranded region adjacent to the bottom of the hairpin and to fold back on itself, giving rise to a "double-hairpin" complex that involved a local triplex. this imposed the recognition, by the third strand, of a "purine" strand containing 6 interspersed pyrimidines out ... | 1996 | 8798660 |
| leishmania mexicana amazonensis: differential display analysis and cloning of mrnas from attenuated and infective forms. | the virulence of leishmania mexicana is determined by the concerted action of several parasite molecules. these cells lose their infectivity to host macrophages after prolonged cultivation in axenic growth media. both virulent and attenuated variants of the parasite cells were cloned. the differential display reverse transcription-polymerase chain reaction technique was employed to understand whether this natural attenuation of the parasite cells is accompanied by differential expression of sele ... | 1996 | 8822812 |
| eosinophil chemotactic activity in leishmania amazonensis promastigotes. | tissue eosinophilia was observed in the subcutaneous tissue of mice shortly after their inoculation not only with living but also with lysed promastigotes of leishmania amazonensis. intraperitoneal inoculation of lysed promastigotes from five different leishmania species (l. donovani, l. chagasi, l. tropica, l. amazonensis, and l. braziliensis) induced eosinophil accumulation in the mouse peritoneum. this eosinophil infiltration was also detected in c5-deficient akr mice, indicating complement i ... | 1996 | 8832727 |
| stable transfection in the monogenetic trypanosomatid leptomonas collosoma--transcription barrier of heterologous trypanosomatid sl rna genes and expression of a chimeric sl rna molecule. | a stable transfection system for the lower trypanosomatid leptomonas collosoma was established using the leishmania expression vector px that was derived from an extrachromosomal amplified dna carrying the dihydrofolate reductase-thymidylate synthase gene. transformants harboring the px vector were selected on geneticin, and cell lines harboring as many as 200 copies per cell were obtained by increasing the drug concentration. the system was utilized to examine the expression of the sl rna genes ... | 1996 | 8888731 |
| possible roles of nitric oxide and peroxynitrite in murine leishmaniasis. | activated macrophages simultaneously synthesize nitric oxide and superoxide anion which can react with each other producing peroxynitrite. consequently, it has been difficult to assess the precise contribution of each of the formed reactive oxygen- and nitrogen-derived species to the microbicidal activities of macrophages, particularly in vivo. to explore this problem, we are examining the formation and potential roles of nitrogen-derived intermediates in leishmania amazonensis murine infection. ... | 1996 | 9070374 |
| complement resistance of leishmania amazonensis promastigotes is independent of parasite proteases and lysis of sensitive forms is not due to natural antibodies in normal human serum. | leishmania amazonensis promastigotes cultivated in vitro differentiate from complement-sensitive to complement-resistant forms. in order to determine the possible involvement of parasite proteases in this process, l. amazonensis promastigotes were collected daily and their proteolytic enzyme patterns analyzed using polacrylamide gels copolymerized with gelatin. although promastigotes at different growth stages showed differences in protease patterns, these changes did not correlate with their su ... | 1996 | 9222424 |
| [canine cutaneous and visceral leishmaniasis and chagas' disease from counties in the triângulo mineiro and alto paranaíba regions, minas gerais state, brazil] | leishmaniasis and chagas' disease were surveyed by indirect immunofluorescence with sera from 331 dogs from uberlândia and coromandel, two counties in the state of minas gerais, brazil. leishmania amazonensis and trypanosoma cruzi antigens were employed. in uberlândia county, 230 sera were studied, of which 200 were from urban areas and 30 rural: 4.5% of urban samples and 6.6% of rural were positive for l. amazonensis antigen. of 89 sera from coromandel, 5.6% were positive for the same test to l ... | 1996 | 10904334 |
| in vitro and in vivo leishmanicidal studies of peperomia galioides (piperaceae). | petroleum ether and methylene chloride extracts of peperomia galioides and three prenylated diphenols, grifolic acid, grifolin and piperogalin exhibited in vitro antileishmanial activity. during the course of infection of balb/c mice with leishmania amazonensis, the treatments with each of these compounds did not influence the progression of the disease. | 1996 | 23195082 |
| leishmanicidal activity of peroxynitrite. | nitric oxide reacts with superoxide to produce peroxynitrite which has been reported to be highly microbicidal to trypanosoma cruzi in phosphate buffer but ineffective against leishmania major in culture medium. this contradiction and the potential importance of peroxynitrite as a cytotoxic effector molecule of both macrophages and neutrophils led us to re-examine its leishmanicidal effects. our results demonstrate that peroxynitrite inhibits growth of leishmania amazonensis promastigotes in a c ... | 1995 | 27405713 |
| leishmania amazonensis: multidrug resistance in vinblastine-resistant promastigotes is associated with rhodamine 123 efflux, dna amplification, and rna overexpression of a leishmania mdr1 gene. | a vinblastine-resistant leishmania amazonensis cell line (rv100) which exhibits cross-resistance to the unrelated drug adriamycin, and thus is considered to be multidrug resistant (mdr), was isolated after stepwise selection with increasing concentrations of vinblastine. this phenotype was partially reverted by the calcium channel antagonist verapamil. drug transport studies using the hydrophobic fluorescent dye rhodamine 123 demonstrated that the mdr cell line has a reduced dye accumulation due ... | 1995 | 8542989 |
| immune evasion by trypanosomatidae: normal aggregated immunoglobulin protects against lysis by the alternative complement pathway. | immunoglobulin fc receptors (fcrs), present in trypanosomatidae pathogenic for mammals, may be a mechanism by which these parasites escape the host immune response. we studied the possible role of these receptors in evasion by the alternative complement pathway. promastigotes of leishmania amazonensis and trypsinized trypomastigotes of trypanosoma cruzi treated with heat-aggregated normal gamma globulin and then incubated with fresh normal guinea pig serum were shown to be more resistant to lysi ... | 1995 | 8555979 |
| therapeutic effect of oral kalanchoe pinnata leaf extract in murine leishmaniasis. | the effect of a leaf extract from kalanchoe pinnata (kp) was investigated in balb/c mice infected with leishmania amazonensis. oral treatment with kp significantly delayed onset of disease as compared to untreated mice or mice receiving kp by the intravenous or topical routes. when initiated at early stages of infection, daily oral doses of 8 mg prevented lesion growth and the effect was long-lasting, comparable to the reference antileishmanial drug glucantime. the decreased lesion growth using ... | 1995 | 8907398 |
| intracellular leishmania amazonensis amastigotes internalize and degrade mhc class ii molecules of their host cells. | in their amastigote stage, leishmania live in mammalian macrophages within parasitophorous vacuoles (pv), organelles of phagolysosomal origin that, in macrophages activated with ifn-gamma, contain major histocompatibility complex (mhc) class ii molecules apparently devoid of invariant chains. we have now studied the fate of pv-associated class ii molecules in mouse bone marrow-derived macrophages infected with l. amazonensis amastigotes using immunocytochemical and biochemical approaches. we hav ... | 1995 | 7593283 |
| up-regulation of t helper 2 and down-regulation of t helper 1 cytokines during murine retrovirus-induced immunodeficiency syndrome enhances susceptibility of a resistant mouse strain to leishmania amazonensis. | resistance to and recovery from leishmania infection is dependent on cell-mediated immunity. c57bl/6 mice are resistant to leishmania amazonensis (la) infection but susceptible to lp-bm5 murine leukemia virus (mulv) infection. mulv infection leads to a state of immunodeficiency characterized by severe compromise of cell-mediated immunity. when infected with la alone, c57bl/6 mice developed a small transient lesion that evolved to spontaneous healing or a lesion with extremely slow growth. lesion ... | 1995 | 7887446 |
| transforming growth factor-beta in human cutaneous leishmaniasis. | transforming growth factor (tgf)-beta has several downregulatory functions on the immune system: inhibition of interleukin-2 receptor induction, decrease of interferon-gamma-induced class ii antigen expression, inhibition of macrophage activation, as well as cytotoxic and lymphokine-activated killer cell generation. tgf-beta has also been recognized as an important immunoregulator in murine leishmaniasis, for which it increases susceptibility to disease. in the present study we evaluate the invo ... | 1995 | 7573370 |
| comparison of new and old world leishmanins in an endemic region of brazil. | the control of leishmaniasis depends on a knowledge of the magnitude of the disease and of exposure to it. delayed-type hypersensitivity testing can detect prior exposure to the parasite, but there is little agreement regarding the choice of an antigen for such testing. new and old world leishmanins were tested in a study of patients with confirmed prior cutaneous leishmaniasis (cl), patients with confirmed prior american visceral leishmaniasis (avl), and controls from areas in espírito santo, b ... | 1995 | 7620013 |
| alterations induced by the antifungal compounds ketoconazole and terbinafine in leishmania. | the antiproliferative effects and ultrastructural alterations induced in vitro by two antifungal compounds, the azole ketoconazole and the allylamine terbinafine on leishmania amazonensis are reported. promastigotes treatment with ketoconazole and terbinafine induced growth arrest and cell lysis in 72 hours. combination of the two agents produced additive effects on promastigote axenic growth and synergistic effects on intracellular amastigote proliferation. the amastigotes, either axenically gr ... | 1995 | 7620457 |
| entry and survival of leishmania amazonensis amastigotes within phagolysosome-like vacuoles that shelter coxiella burnetii in chinese hamster ovary cells. | coxiella burnetii, a rickettsia, and leishmania amazonensis, a protozoan flagellate, lodge in their host cells within large phagolysosome-like vacuoles. in the present study, c. burnetii-infected vero or cho cells were superinfected with l. amazonensis amastigotes to determine if these parasites can home to and survive within heterologous vacuoles. six hours after superinfection, leishmania amastigotes were located almost exclusively within large coxiella-containing vacuoles. thereafter, the num ... | 1995 | 7642284 |
| accurate modification of the trypanosome spliced leader cap structure in a homologous cell-free system. | during rna maturation in trypanosomatid protozoa, trans-splicing transfers the spliced leader (sl) sequence and its cap from the sl rna to the 5' end of all mrnas. in trypanosoma brucei and crithidia fasciculata the sl rna has an unusual cap structure with four methylated nucleotides following the 7-methylguanosine residue (cap 4). since modification of the 5' end of the sl rna is a pre-requisite for trans-splicing activity in t. brucei, we have begun to characterize the enzyme(s) involved in th ... | 1995 | 7657609 |
| identification of leishmania species by a specific dna probe that is conserved only in the maxicircle dna of human-infective leishmania parasites. | an a + t-rich repeated dna sequence cloned from maxicircle dna of leishmania mexicana amazonensis was found to be conserved in the maxicircles of human-infective leishmania species but totally absent from non-human-infective ones. differences in the pattern of distribution of this repeated sequence in the maxicircles of each human-infective leishmania species potentially allow the development of a sensitive probe to differentiate among these species. | 1995 | 7658091 |
| leishmanial protein kinase c modulates host cell infection via secreted acid phosphatase. | to study the role of parasite protein kinase c (pkc) activity in the uptake of leishmania amazonensis by mononuclear phagocytes we treated the parasites with 12-o-tetradecanoyl phorbol-13-acetate (tpa) and/or sphingosine, before interaction assays. promastigotes of leishmania amazonensis were incubated with 20 ng/ml tpa and/or 50 ng/ml sphingosine before the interaction with murine peritoneal macrophages. the short treatment enhanced about 200% the parasite association with the host cells, where ... | 1995 | 7664753 |