| cd4+, cd8+ and cd4- cd8- t cell-subsets can confer protection against leishmania m. mexicana infection. | we studied the role of cd4+, cd8+, cd4- cd8- t cells and igg anti-leishmania after infection or vaccination in the cba/ca mouse. mice were either infected with l. m. mexicana promastigotes or vaccinated with parasite-membrane antigens incorporated into liposomes. successfully vaccinated mice were used as cell-donors in adoptive transfer experiments. naive, syngeneic recipients received highly-enriched cd4+, cd8+ or cd4- cd8- t cells from those two set of donors and challenged with live parasites ... | 1995 | 8524085 |
| visceral leishmaniasis due to a leishmania variant that shares kinetoplast dna sequences with leishmania braziliensis and leishmania mexicana in a patient infected with human immunodeficiency virus: identification of the leishmania species with use of the polymerase chain reaction. | | 1995 | 8527582 |
| isolation of lmcpc, a gene encoding a leishmania mexicana cathepsin-b-like cysteine proteinase. | | 1995 | 8577339 |
| glycosylphosphatidylinositol toxin of plasmodium up-regulates intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and e-selectin expression in vascular endothelial cells and increases leukocyte and parasite cytoadherence via tyrosine kinase-dependent signal transduction. | in this study we demonstrate that glycosylphosphatidylinositol (gpi) of malaria parasite origin directly increases cell adhesion molecule expression in purified huvecs in a dose- and time-dependent manner, resulting in a marked increase in parasite and leukocyte cytoadherence to these target cells. the structurally related glycolipids dipalmitoyl-phosphatidylinositol and im4 glycoinositolphospholipid of leishmania mexicana had no such activity. malarial gpi exerts this effect by activation of an ... | 1996 | 8596041 |
| glycosylphosphatidylinositol toxin of plasmodium induces nitric oxide synthase expression in macrophages and vascular endothelial cells by a protein tyrosine kinase-dependent and protein kinase c-dependent signaling pathway. | in this study, we demonstrate that glycosylphosphatidylinositol (gpi) is a major toxin of plasmodium falciparum origin responsible for nitric oxide (no) production in host cells. purified malarial gpi is sufficient to induce no release in a time- and dose-dependent manner in macrophages and vascular endothelial cells, and regulates inducible no synthase expression in macrophages. gpi-induced no production was blocked by the no synthase-specific inhibitor l-n-monomethylarginine. gpi also synergiz ... | 1996 | 8596042 |
| histone h1 and core histones in leishmania and crithidia: comparison with trypanosoma. | the trypanosomatidae family is characterized by flagellated protozoa presenting a kinetoplast. several genera of this family contain species that are pathogenic to man and domestic animals. their chromatin is not condensed into chromosomes during cell division. as a contribution to the understanding of basic aspects of their genome organization, we present a systematic characterization of the histones from three genera of the trypanosomatidae family. crithidia fasciculata and leishmania mexicana ... | 1996 | 8612672 |
| 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 |
| the genomic organization of the hsp83 gene locus is conserved in three leishmania species. | | 1996 | 8617351 |
| 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 |
| differential expression of chemokines in patients with localized and diffuse cutaneous american leishmaniasis. | the abundance of macrophages in localized cutaneous leishmaniasis (lcl) and diffuse cutaneous leishmaniasis (dcl) lesions and differences in the composition of t cell subsets indicate involvement of cell-specific chemotaxis processes. the expression of macrophage chemoattractant protein (mcp)-1, macrophage inflammatory protein (mip)-1 alpha and -1 beta, rantes (regulated on activation, normal t cell expressed and secreted), i-309, and interleukin-8 were investigated in lesions of patients with l ... | 1996 | 8627035 |
| evidence from disruption of the lmcpb gene array of leishmania mexicana that cysteine proteinases are virulence factors. | the mammalian form of the protozoan parasite leishmania mexicana contains high activity of a cysteine proteinase (lmcpb) encoded on a tandem array of 19 genes (lmcpb). homozygous null mutants for lmcpb have been produced by targeted gene disruption. all life-cycle stages of the mutant can be cultured in vitro, demonstrating that the gene is not essential for growth or differentiation of the parasite. however, the mutant exhibits a marked phenotype affecting virulence-- its infectivity to macroph ... | 1996 | 8650210 |
| 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 |
| amphotericin b kills unicellular leishmanias by forming aqueous pores permeable to small cations and anions. | the polyene antibiotic amphotericin b (amb) is known to form two types of ionic channels across sterol-containing liposomes, depending on its concentration and time after mixing (cohen, 1992). in the present study, it is shown that amb only kills unicellular leishmania promastigotes (lps) when aqueous pores permeable to small cations and anions are formed. changes of membrane potential across ergosterol-containing liposomes and lps were followed by fluorescence changes of 3,3' dipropylthiadicarb ... | 1996 | 8660406 |
| leishmania mexicana p12cks1, a homologue of fission yeast p13suc1, associates with a stage-regulated histone h1 kinase. | we have isolated a leishmania mexicana homologue of the fission yeast suc1 gene using pcr with oligonucleotides designed to conserved regions of cdc2 kinase subunits (cks). the product of cks1 is a 12 kda polypeptide, which has 70% identity with human p9cks1 and 44% identity with fission yeast p13suc1.p12cks1 was detected in the three life-cycle stages of l. mexicana by immunoblotting. recombinant p12cks1 (p12cks1his) bound to agarose beads was used as a matrix to affinity-select histone h1 kina ... | 1996 | 8670159 |
| genetic susceptibility to leishmanial infections: studies in mice and man. | two important recent advances in leishmania immunology are: (i) the demonstration of a dramatic dichotomy in t helper 1 versus t helper 2 subset expansion leading to protection versus disease exacerbation; and (ii) analysis of the macrophage activation pathways leading to enhanced intracellular killing of parasites, in particular the tumour necrosis factor alpha (tnf alpha)-dependent sustained induction of the inducible nitric oxide synthase gene (nos2) leading to the generation of large amounts ... | 1996 | 8684837 |
| detection of cruzipain, the major cysteine proteinase from trypanosoma cruzi and its c-terminal extension in biological fluids during experimental infection in mice. | monoclonal antibodies (moabs) specific for unique epitopes of the catalytic domain of cruzipain (crz) were used to develop a two-site sandwich elisa specific for native crz. in addition, the authors developed a sandwich elisa that allowed the detection of the protease c-terminal domain (ct) using a combination of a moab specific for the ct and rabbit anti-crz iggs. both assays were sensitive with detection limits of 2 ng/ml and 0.7 ng/ml, respectively. the assays were assessed for applicability ... | 1996 | 8711424 |
| ouabain-sensitive na+,k(+)-atpase in the plasma membrane of leishmania mexicana. | the mechanism responsible for the regulation of intracellular na+ and k+ concentrations in trypanosomatids is unknown. in higher eukaryotes a ouabain-sensitive na+,k(+)-atpase located in the plasma membrane is the main mechanism for the regulation of the intracellular concentrations of na+ and k+, while in trypanosomatids there are conflicting evidences about the existence of this type of atpase. by the use of a highly enriched plasma membrane fraction, we showed that an ouabain-sensitive na+,k( ... | 1995 | 8719159 |
| the leishmania promastigote surface antigen 2 complex is differentially expressed during the parasite life cycle. | the promastigote surface antigen 2 (psa-2) complex comprises a family of antigenically similar polypeptides of m(r) 96,000, 80,000 and 50,000, anchored to the membrane with glycosylphosphatidylinositol. although psa-2 was initially detected only in promastigotes, northern blot analysis indicated that mrna transcripts are also present in amastigotes. unlike the situation in promastigotes, where at least four major transcripts (2.6-5.3 kb) were detected, only one major (2.6 kb) and two minor trans ... | 1995 | 8719160 |
| glucose transport in amastigotes and promastigotes of leishmania mexicana mexicana. | promastigotes and amastigotes of leishmania mexicana mexicana transported 2-deoxy-d-glucose (2-dog) by a saturable process with a km of 24 +/- 3 microm and vmax of 2.21 nmol min-1 (mg protein)-1 for the promastigote and a km of 29 +/- 8 microm and vmax of 0.13 nmol min-1 (mg protein)-1 for the amastigote stage. amastigotes incorporated 2-dog maximally at ph 5.0, while for promastigotes the optimum was at ph 7.0. mid-log phase promastigotes were found to accumulate 2-dog via a stereospecific carr ... | 1995 | 8719247 |
| the role of macrophage receptors in adhesion and uptake of leishmania mexicana amastigotes. | amastigotes of the protozoan parasite leishmania proliferate in phagolysosomes of mammalian macrophages. propagation of the infection is considered to occur by host-cell rupture and uptake of released parasites by uninfected macrophages. in this study, the kinetics of binding of l mexicana mexicana amastigotes to cos cells and to cos cells transfected with three different macrophage receptors (fcrii-b2, receptor for the fc-domain of immunoglobulins; cr3, complement type 3 receptor and the mannos ... | 1995 | 8719878 |
| 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 |
| [excretion of promastigotes of leishmania pifanoi by experimentally infected lutzomyia youngi]. | the increase in the promastigotes population of leishmania pifanoi in lutzomyia youngi experimentally infected and kept on 50% sacarose under constant conditions of temperature and humidity is described. two stages in the differentiation and growth of the parasites are recognised between two and twenty-four hours after meals. the pleomorphic differentiation of the amastigotes in short promastigotes which multiply by binary division for 60 hours, when the rupture of the peritrophic membrane occur ... | 1995 | 8734975 |
| 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 |
| the rational design of trypanocidal drugs: selective inhibition of the glyceraldehyde-3-phosphate dehydrogenase in trypanosomatidae. | within the framework of a project aimed at the structure-based design of drugs for use against sleeping sickness, selective inhibitors were designed, synthesised and tested. the target protein was glycosomal glyceraldehyde-3-phosphate dehydrogenase (gapdh) and the adenosine part of the nad cofactor was chosen as lead. after one design cycle and exploiting the selectivity cleft in trypanosomal gapdh near the c2 of the adenosine ribose, a selective inhibitor, 2'-deoxy-2'-(3-methoxybenzamido)adenos ... | 1995 | 8745924 |
| 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 |
| using evolutionary changes to achieve species-specific inhibition of enzyme action--studies with triosephosphate isomerase. | many studies that attempt to design species-specific drugs focus on differences in the three-dimensional structures of homologous enzymes. the structures of homologous enzymes are generally well conserved especially at the active site, but the amino-acid sequences are often very different. we reasoned that if a non-conserved amino acid is fundamental to the function or stability of an enzyme from one particular species, one should be able to inhibit only the enzyme from that species by using an ... | 1995 | 8807818 |
| 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 |
| microtubule inhibitors: structure-activity analyses suggest rational models to identify potentially active compounds. | trifluralin, a dinitroaniline microtubule inhibitor currently in use as an herbicide, has been shown to inhibit the proliferation of plasmodium falciparum, trypanosoma brucei, and several species of leishmania, in vitro. as a topical formulation, trifluralin is also effective in vivo (in balb/c mice) against leishmania major and leishmania mexicana. although trifluralin and other dinitroaniline herbicides show significant activity as antiparasitic compounds, disputed indications of potential car ... | 1996 | 8849257 |
| carbon sources for fatty acid and sterol biosynthesis in leishmania species. | | 1996 | 8878978 |
| 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 |
| treatment of new world cutaneous and mucosal leishmaniases. | the most extensive investigations of treatment of new world cutaneous leishmaniasis have been performed against l. panamensis disease in colombia, and the relative value of regimens shown there may be instructive for disease from other areas. in colombia, a 90-95% cure rate was achieved with three different drug regimens: the standard regimen of pentavalent antimony (20 mg/ kg/day for 20 days parenterally) a short course of pentamidine (3 mg/kg every other day for four injections intramuscularly ... | 1996 | 8889330 |
| stage-specific expression of the leishmania mexicana paraflagellar rod protein pfr-2. | a screen for leishmania mexicana genes encoding promastigote-specific flagellar proteins resulted in isolation of genes encoding the major components of the paraflagellar rod. one of these, pfr-2, was characterized extensively. pfr-2 genes are present in the genome as a tandem array of three genes designated pfr-2a, pfr-2b, pfr-2c. pfr-2a and pfr-2b are encoded by a 3.1 transcript while pfr-2c is encoded by a 3.8-kb transcript that has a 3' utr different from that of the 3.1-kb transcript. both ... | 1996 | 8892290 |
| vaccination of c57bl/6 mice against cutaneous leishmaniosis. kinetics of antibody synthesis and induction of cellular responses. | in this report, the effectiveness of vaccination of c57bl/6 mice and its association to long term production of igg anti-leishmania, delayed type hypersensitivity response (dth) and the enlargement of the spleen associated to hyperplasia or parasite visceralization were studied. mice were vaccinated with leishmania-membrane antigens incorporated into liposomes, and two weeks later, animals received a homologous challenge with living amastigotes. antibody levels were weekly recorded during 18 wee ... | 1995 | 8900933 |
| comparison of the leishmanicidal activity of fungizone, liposomal amb and amphotericin b incorporated into egg lecithin-bile salt mixed micelles. | we compared leishmanicidal activity of five formulations of amphotericin b (amb). amb used as fungizone immediately caused cell lysis, at lower concentrations partial, and at higher concentrations total; the non-lysed cells reassuming growth. amb formulated with egg-lecithin and bile salt at doses equivalent to those of fungizone was not active, whereas at higher doses it resulted in a delayed but complete inhibition of cell growth. the activity of liposomal amb was comparable to that of fungizo ... | 1995 | 8907695 |
| efficient technique for screening drugs for activity against trypanosoma cruzi using parasites expressing beta-galactosidase. | a new drug screening method was devised utilizing trypanosoma cruzi cells that express the escherichia coli beta-galactosidase gene. transfected parasites catalyze a colorimetric reaction with chlorophenol red beta-d-galactopyranoside as substrate. parasite growth in the presence of drugs in microtiter plates was quantitated with an enzyme-linked immunosorbent assay reader. the assay was performed with the mammalian form of t. cruzi that requires intracellular growth on a monolayer of fibroblast ... | 1996 | 8913471 |
| cloning and characterization of the nad-linked glycerol-3-phosphate dehydrogenases of trypanosoma brucei brucei and leishmania mexicana mexicana and expression of the trypanosome enzyme in escherichia coli. | a polyclonal antiserum raised against the purified glycosomal glycerol-3-phosphate dehydrogenase of trypanosoma brucei brucei has been used to identify the corresponding cdna clone in a t.b. brucei expression library. this cdna was subsequently used to obtain genomic clones containing glycerol-3-phosphate dehydrogenase genes. two tandemly arranged genes were detected in these clones. characterization of one of the genes showed that it codes for a polypeptide of 353 amino acids, with a molecular ... | 1996 | 8920004 |
| 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 |
| gene disruptions indicate an essential function for the lmmcrk1 cdc2-related kinase of leishmania mexicana. | the generation of homozygous null mutants for the crk1 cdc2-related kinase of leishmania mexicana was attempted using targeted gene disruption. promastigote mutants heterozygous for crk1 were readily isolated with a hyg-targeting fragment, but attempts to create null mutants by second-round transfections with a bie-targeting fragment yielded two classes of mutant, neither of which was null. first, the transfected fragment formed an episome; second, the cloned transfectants were found to contain ... | 1996 | 8939439 |
| leishmaniasis in texas: epidemiology and clinical aspects of human cases. | twenty-seven autochthonous cases of cutaneous leishmaniasis in texas were identified by contact with dermatologists and state health department officials, and by a review of medical records, pathology reports, and previously published case reports. fifteen cases were previously unreported. although the date of onset of the first recognized case was 1903, in 20 of the cases the date of onset of the lesion(s) was in 1980-1989. twelve cases were female; 15 were male. age at diagnosis ranged from tw ... | 1996 | 8940988 |
| 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 |
| gene cloning and cellular localization of a membrane-bound acid phosphatase of leishmania mexicana. | in a previous publication, we described the purification of a membrane-bound acid phosphatase of leishmania mexicana as a heterogeneously n-glycosylated protein of an apparent molecular mass of 70000-72000 expressed in both the promastigote and the amastigote stage of the parasite [19]. screening of a genomic dna library of l. mexicana with degenerate oligonucleotides designed according to the nh2-terminus of the protein led to the cloning of the lmmbap gene, which is present in one copy per hap ... | 1996 | 8946382 |
| il-6 produced by macrophages infected with mycobacterium species suppresses t cell responses. | the ability of mycobacterium bovis calmette-guérin bacillus-infected bone marrow-derived macrophages to process and present exogenously added ags to t cells and stimulate their growth and production of il-2 was examined. the infected macrophages were inhibited in their ability to activate t cells, and this inhibition could be transferred to uninfected macrophages with filtered supernatants from mycobacteria-infected macrophages. the inhibition was not due to decreases in macrophage viability, ag ... | 1997 | 8977207 |
| antigen presentation by leishmania mexicana-infected macrophages: activation of helper t cells by a model parasite antigen secreted into the parasitophorous vacuole or expressed on the amastigote surface. | leishmania are protozoan parasites which invade mammalian macrophages and multiply as amastigotes in phagolysosomes (parasitophorous vacuoles). using l. mexicana and bone marrow-derived macrophages (bmm), the question is addressed whether infected bmm induced to express major histocompatibility complex class ii molecules can present defined antigens to specific t helper type 1 cells. as a model antigen, a membrane-bound acid phosphatase (map), a minor protein associated with intracellular vesicl ... | 1996 | 8977317 |
| leishmania-infected macrophages sequester endogenously synthesized parasite antigens from presentation to cd4+ t cells. | cd4+ t cell lines raised against the protective leishmanial antigens gp46 and p8 were used to study the presentation of endogenously synthesized leishmania antigens by infected cells. using two different sources of macrophages, the i4.07 macrophage cell line (h-2k) which constitutively expresses major histocompatibility complex (mhc) class ii molecules, and elicited peritoneal exudate cells, we found that cells infected with leishmania amastigotes presented little, if any endogenously synthesize ... | 1996 | 8977318 |
| effects of steroidal allenic phosphonic acid derivatives on the parasitic protists leishmania donovani, leishmania mexicana mexicana, and pneumocystis carinii carinii. | several pathogenic fungi and protozoa are known to have sterols distinct from those of their mammalian hosts. of particular interest as targets for drug development are the biosyntheses of the sterols of important parasites such as the kinetoplastid flagellates and the aids-associated opportunistic protist pneumocystis carinii. these pathogens synthesize sterols with an alkyl group at c-24, and some have a double bond at c-22 of the side chain. humans and other mammalian hosts are incapable of c ... | 1997 | 8980773 |
| 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 |
| proteophosphoglycan secreted by leishmania mexicana amastigotes causes vacuole formation in macrophages. | the amastigote form of leishmania mexicana parasites colonizes macrophage phagolysosomes and induces the enlargement of these compartments to form huge parasitophorous vacuoles. we report here that a purified secreted amastigote product, proteophosphoglycan, is a macromolecule which causes vacuolization of peritoneal macrophages in vitro. secretion of this glycoconjugate by intracellular parasites may contribute to the expansion of phagolysosomal compartments in infected cells. | 1997 | 9009342 |
| activity of juvenile hormone and juvenile hormone analogues on the growth of trypanosoma cruzi. | the effects of juvenile hormone-iii (jh-iii) and the juvenile hormone analogues (jha) methoprene and fenoxycarb on the growth and macromolecular biosynthesis in trypanosoma cruzi were studied in vitro. it was observed that jh-iii and jha blocked growth and 3h-thymidine incorporation without killing the cells within certain concentrations (< or = 1 x 10(-4) m), but they caused cellular death at concentrations over 1 x 10(-3) m. the inhibitory effect on growth was partially reversible. on the othe ... | 1996 | 9010355 |
| [impact of new methodologies in the study of parasites]. | | 1996 | 9011513 |
| leishmania mexicana: binding of promastigotes to type i collagen. | during leishmania infection, parasites are inoculated to the human host through the bite of a sandfly vector into the dermis, where they first interact with tissue components, cells and extracellular matrix molecules. since collagen is the most abundant component of the skin matrix, we investigated whether there is a specific interaction of leishmania mexicana promastigotes with this host component. promastigotes were able to attach to collagen fibrils and move through the matrix of mouse skin s ... | 1997 | 9030665 |
| [study of cases of leishmaniasis in the province of salta: evidences of mixed infection with trypanosoma cruzi and leishmania spp]. | in many regions of south america there are overlapping endemic areas for american trypanosomiasis (chagas' disease) and leishmaniasis. t. cruzi and leishmania spp, the causative agents of these parasitoses belong to the trypanosomatidae family and share various antigens that cause cross-reactivity in serological diagnosis when complex antigenic mixtures are used. we studied patients who sought medical attention because of cutaneous or mucocutaneous lesions typical of leishmaniasis infection. the ... | 1996 | 9035482 |
| transfer of phagocytosed particles to the parasitophorous vacuole of leishmania mexicana is a transient phenomenon preceding the acquisition of annexin i by the phagosome. | the eukaryotic intracellular pathogen leishmania mexicana resides inside macrophages contained within a membrane bound parasitophorous vacuole which, as it matures, acquires the characteristics of a late endosomal compartment. this study reports the selectivity of fusion of this compartment with other particle containing vacuoles. phagosomes containing zymosan or live listeria monocytogenes rapidly fused with l. mexicana parasitophorous vacuoles, while those containing latex beads or heat killed ... | 1997 | 9044049 |
| 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 |
| vaccination of different strains of mice against cutaneous leishmaniosis: usefulness of membrane antigens encapsulated into liposomes by intraperitoneal and subcutaneous administration. | the objective of this study was to assess the usefulness of parasite-surface molecules reconstituted into liposomes to vaccinate four different strains of mice (c57bl/10, cba/ca, c57bl/6 and nzb) with different levels of susceptibility to l. m. mexicana infection and to find out possible increases in specific antibody response after vaccination, but before infection with virulent promastigotes. mice were vaccinated with parasite membrane antigens incorporated into liposomes and antibody levels w ... | 1997 | 9078587 |
| intermediate filament-like proteins in leishmania. | | 1997 | 9080653 |
| 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 |
| an axenic amastigote system for drug screening. | currently available primary screens for selection of candidate antileishmanial compounds are not ideal. the choices include screens that are designed to closely reflect the situation in vivo but are labor-intensive and expensive (intracellular amastigotes and animal models) and screens that are designed to facilitate rapid testing of a large number of drugs but do not use the clinically relevant parasite stage (promastigote model). the advent of successful in vitro culture of axenic amastigotes ... | 1997 | 9087496 |
| purification of the lipophosphoglycan from two leishmania mexicana strains by lectin affinity chromatography. | two lipophosphoglycans (lpg) from two leishmania mexicana (soberano and yucatan) strains, isolated in mexico, were purified by affinity chromatography with the con a lectin. the lpg from each strain, with a 10 kda molecular weight, possesses two fractions: one with high mannose concentrations and the other with a more heterogeneous saccharidic composition; the mannose-rich fraction and the heterogeneous fraction from the yucatan strain show a single band of identity with rabbit igg against proma ... | 1997 | 9090720 |
| signal transduction in macrophages by glycosylphosphatidylinositols of plasmodium, trypanosoma, and leishmania: activation of protein tyrosine kinases and protein kinase c by inositolglycan and diacylglycerol moieties. | the perturbation of various glycosylphosphatidylinositol (gpi)-anchored surface proteins imparts profound regulatory signals to macrophages, lymphocytes and other cell types. the specific contribution of the gpi moieties to these events however is unclear. this study demonstrates that purified gpis of plasmodium falciparum, trypanosoma brucei, and leishmania mexicana origin are sufficient to initiate signal transduction when added alone to host cells as chemically defined agonists. gpis (10 nm-1 ... | 1997 | 9108098 |
| cloning, expression, purification and characterization of triosephosphate isomerase from trypanosoma cruzi. | the gene that encodes for triosephosphate isomerase from trypanosoma cruzi was cloned and sequenced. in t. cruzi, there is only one gene for triosephosphate isomerase. the enzyme has an identity of 72% and 68% with triosephosphate isomerase from trypanosoma brucei and leishmania mexicana, respectively. the active site residues are conserved: out of the 32 residues that conform the interface of dimeric triosephosphate isomerase from t. brucei, 29 are conserved in the t. cruzi enzyme. the enzyme w ... | 1997 | 9108237 |
| [presence of metacyclical promastigotes of leishmania pifanoi in the hypopharynx of lutzomyia youngi and their sugar consumption]. | the presence of metacyclical promastigotes of leishmania pifanoi in the hypopharyngeal duct of lutzomyia youngi is reported. the insects were experimentally infected by engorgement on the tarsal lesions of hamsters. the metacyclics, whose morphology is illustrated, appeared in the hypopharynx 5 to 9 days after engorgement; they were more frequently found in the insects fed on unrefined commercial sugar. they role of amino derivates of glucose and galactose, as well as of amino acids in the devel ... | 1996 | 9110469 |
| naturally azole-resistant leishmania braziliensis promastigotes are rendered susceptible in the presence of terbinafine: comparative study with azole-susceptible leishmania mexicana promastigotes. | leishmania braziliensis (isolate 2903) was naturally resistant to ketoconazole or the bis-triazole d0870, inhibitors of sterol c-14 demethylase, which produced only moderate effects on the proliferation of promastigotes at 10 microm. in contrast, leishmania mexicana (isolate nr) was extremely susceptible to the azoles, as complete growth arrest and cell lysis were induced by incubation of the parasites with 0.05 microm concentrations of the drugs for 72 h. the opposite response was observed with ... | 1996 | 9124841 |
| ether lipid metabolism, gpi anchor biosynthesis, and signal transduction are putative targets for anti-leishmanial alkyl phospholipid analogues. | | 1996 | 9131149 |
| a two years study on vectors of cutaneous leishmaniasis. evidence for sylvatic transmission cycle in the state of campeche, mexico. | vectors of cutaneous leishmaniasis in the state of campeche were studied in relation to the transmission cycle of leishmania (le.) mexicana. to determine how transmission of leishmaniasis occurs, we collected phlebotomine sand flies for two years. in the first year (october 1990 to november 1991) the collections were made with cdc light traps, shannon traps and direct captures at natural shelters around the village (< 200 m) of la libertad. in the second year (february 1993 to january 1994) the ... | 1996 | 9137741 |
| [cutaneous leishmaniasis and leishmania species in french guiana]. | | 1996 | 9139207 |
| 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 |
| leishmania spp.: nitric oxide-mediated metabolic inhibition of promastigote and axenically grown amastigote forms. | the antimicrobial effect of activated macrophages on parasites involves nitric oxide (no). no induces intracellular parasite killing in murine leishmaniasis. nevertheless, the mechanisms of action of no as a final effector molecule on intracellular forms of leishmania are unknown. the recent development of axenically grown amastigote forms of different leishmania species allowed direct investigation of no activity on active and dividing populations of the mammalian stage of various leishmania sp ... | 1997 | 9149241 |
| the multiple cpb cysteine proteinase genes of leishmania mexicana encode isoenzymes that differ in their stage regulation and substrate preferences. | the cpb genes of leishmania mexicana encode stage-regulated, cathepsin l-like cysteine proteinases that are leishmanial virulence factors. field inversion gel electrophoresis and genomic mapping indicate that there are 19 cpb genes arranged in a tandem array. five genes from the array have been sequenced and their expression analyzed. the first two genes, cpb1 and cpb2, differ significantly from the remaining 17 copies (cpb3-cpb19) in that: 1) they are expressed predominantly in metacyclic proma ... | 1997 | 9162063 |
| uptake of z-tyr[125i]-alachn2, an irreversible cysteine proteinase inhibitor, by lesion amastigotes, axenic amastigotes and promastigotes of leishmania mexicana. | radioiodinated n-benzyloxycarbonyl-tyrosyl-alanyl diazomethane (z-tyr[125i]-alachn2) was previously shown to selectively label two (28 and 31 kda) leishmania mexicana cysteine proteinases common to both the promastigote and the amastigote stages. here we have confirmed the specificity of the compound towards two similar enzymes of axenic l. mexicana amastigotes and demonstrated that lesion amastigotes, axenic amastigotes and stationary promastigotes internalized the 125i-labeled inhibitor at dif ... | 1996 | 9181079 |
| 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 |
| altered transport properties of pentamidine-resistant leishmania donovani and l. amazonensis promastigotes. | pentamidine-resistant clones of leishmania donovani and l. amazonensis promastigotes were developed by increase of the drug pressure in the culture medium and characterized. the resistant clones could grow in 40 and 20 microm pentamidine as determined for l. donovani and l. amazonensis, respectively, with 50% inhibitory concentrations (ic50 values) being 140 and 60 microm, which were 18 and 75 times higher than those recorded for the parental clones, respectively. biochemical analysis of the clo ... | 1997 | 9197387 |
| alpha-difluoromethylornithine-resistant cell lines obtained after one-step selection of leishmania mexicana promastigote cultures. | proliferation of leishmania mexicana promastigotes in synthetic medium can be blocked by the depletion of intracellular polyamine pools induced by the presence of d,l-alpha-difluoromethylornithine (dfmo), a specific and irreversible inhibitor of ornithine decarboxylase (odc). here we report that dfmo-resistant cell lines growing normally at dfmo levels of 10 mm have been obtained from non-proliferating cultures after a single-step selection in the presence of high concentrations of the drug. the ... | 1997 | 9210409 |
| 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 |
| experimental infection of balb/c mice with leishmania panamensis and leishmania mexicana: induction of early ifn-gamma but not il-4 is associated with the development of cutaneous lesions. | resistance to the leishmaniae is associated with interferon (ifn)-gamma mediated activation of macrophages. in this study, balb/c mice were infected with three leishmania strains that cause progressively growing cutaneous lesions without obvious dissemination: l. mexicana mexicana giving rise to rapidly growing lesions, and l. (viannia) panamensis and l. mexicana-like, which both cause slowly developing lesions. the rate of lesion growth was compared to induction of early local and systemic ifn- ... | 1997 | 9246206 |
| glycosphingolipid antigens from leishmania (l.) amazonensis amastigotes. binding of anti-glycosphingolipid monoclonal antibodies in vitro and in vivo. | specific glycosphingolipid antigens of leishmania (l.) amazonensis amastigotes reactive with the monoclonal antibodies (moabs) st-3, st-4 and st-5 were isolated, and their structure was partially elucidated by negative ion fast atom bombardment mass spectrometry. the glycan moieties of five antigens presented linear sequences of hexoses and n-acetylhexosamines ranging from four to six sugar residues, and the ceramide moieties were found to be composed by a sphingosine d18:1 and fatty acids 24:1 ... | 1997 | 9246238 |
| antiproliferative effect of illimaquinone on leishmania mexicana. | illimaquinone, a sponge metabolite that disrupts the golgi complex in mammalian cells, stopped proliferation and induced morphological and ultrastructural changes in promastigotes of l. mexicana. radioactive labeling of proteins demonstrates an increased excretion function and diminution of membrane acid phosphatase activity, due probably to the vesiculation of the golgi complex and alteration of the cell protein sorting mechanism. the result indicated that illimaquinone could be useful for the ... | 1997 | 9268485 |
| 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 |
| cathepsin b-like cysteine proteinase-deficient mutants of leishmania mexicana. | mutants null for the cathepsin b-like cysteine proteinase gene (cpc) of leishmania mexicana have been generated by targeted gene disruption. the gene deletion was confirmed using a polymerase chain reaction (pcr) method with cpc-specific primers and genomic dna isolated from the mutants. cpc was re-expressed in the null mutants from an episomal vector. re-expression of the enzyme (cpc) was detected by western blotting with a specific anti-peptide antiserum. the cpc null mutants grew apparently n ... | 1997 | 9274867 |
| ecological interactions of visceral leishmaniasis in the state of bahia, brazil. | the laboratory and field observations summarized in this paper on visceral leishmaniasis ecology in the state of bahia, brazil are based on the author's observations over the past 35 years in a number of state's foci, public health records and literature citations. the disease is endemic with epidemic outbreaks occurring every ten years and its geographical distribution is expanding rapidly in the last years. leishmania chagasi is the main ethiologic agent of the visceral leishmaniasis but le. a ... | 1996 | 9283643 |
| the dihydroxyacetonephosphate pathway for biosynthesis of ether lipids in leishmania mexicana promastigotes. | biosynthetic studies using both [14c]- and [32p]-labelled substrates and a cell-free system to synthesise 1-o-alkyl moieties in glycerolipids, have shown that the three initial steps in ether-lipid biosynthesis in leishmania mexicana promastigotes resemble those described for mammals and are associated with glycosomes. purified glycosomes were able to sequentially synthesise the first intermediates of the ether-lipid biosynthetic pathway [acyl-dihydroxyacetonephosphate (dhap), alkyl-dhap and acy ... | 1997 | 9297701 |
| 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 |
| antibody response against a leishmania donovani amastigote-stage-specific protein in patients with visceral leishmaniasis. | the antibody response against an amastigote-specific protein (a2) from leishmania donovani was investigated. sera from patients with trypanosomiasis and various forms of leishmaniasis were screened for anti-a2 antibodies. sera from patients infected only with l. donovani or leishmania mexicana specifically recognized the a2 recombinant protein. these results were consistent with karyotype analyses which revealed that the a2 gene is conserved in l. donovani and l. mexicana strains. the potential ... | 1997 | 9302200 |
| seroepidemiological studies of cutaneous leishmaniasis in the campeche state of méxico. | seroepidemiological studies of cutaneous leishmaniasis were carried out in 169 individuals in a rural area of the campeche state of méxico. fifty showed cutaneous lesions suggestive of leishmaniasis, 70% were parasite positive and 96% skin test positive. an overall 40% positivity to skin test with montenegro's antigen was found. most of the affected individuals were males from 11 to 30 years-old. antibodies were determined by immunofluorescent antibody test (ifa) and by western blot. two antigen ... | 1997 | 9302408 |
| the role of chemokines and accessory cells in the immunoregulation of cutaneous leishmaniasis. | the course of infection with leishmania parasites is determined by the type of the developing cd4+ t cell immune response. macrophages and langerhans cells/dendritic cells play a decisive role in the interaction between the parasites and the host's immune system because they serve as host cells, as accessory cells that present parasite antigen, deliver costimulatory signals and secrete cytokines modulating the t cell activity and as effector cells eliminating the microorganisms. therefore, we pu ... | 1997 | 9303204 |
| in vitro life cycle of pentamidine-resistant amastigotes: stability of the chemoresistant phenotypes is dependent on the level of resistance induced. | using a continuous drug pressure protocol, we induced pentamidine resistance in an active and dividing population of amastigote forms of leishmania mexicana. we selected in vitro two clones with different levels of resistance to pentamidine, with clone lmpent5 being resistant to 5 microm pentamidine, while clone lmpent20 was resistant to 20 microm pentamidine. resistance indexes (50% inhibitory concentration [ic50] after drug presure/ic50 before drug pressure) of 2 (lmpent5) and 6 (lmpent20) wer ... | 1997 | 9303381 |
| treatment of cutaneous leishmaniasis with localized current field (radio frequency) in tabasco, mexico. | in mexico cutaneous leishmaniasis (cl) occurs in 17 of 32 states, and is a serious public health problem. this is a report of treatment of cl patients in the state of tabasco, mexico with a localized current field-radio frequency (lcf-rf) device to generate precisely controlled heat as an alternative to prohibitively expensive drug treatment. it was not a controlled clinical trial, but rather an evaluation of the feasibility of this form of treatment for all cl patients encountered in the endemi ... | 1997 | 9311641 |
| incorporation of ion channels from the plasma membrane of leishmania mexicana into planar bilayers. | | 1995 | 9334444 |
| 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 |
| specific inhibitory effect of 3-deazaneplanocin a against several leishmania mexicana and l. braziliensis strains. | the growth inhibitory effect of 3-deazaneplanocin a (c3npca) was tested against some pathogenic members of the family of american trypanosomatidae. under our culture conditions, c3npca displayed a strongly and uniformly leishmanistatic effect on all 23 american leishmania (l. mexicana and l. brasiliensis) strains in the study (mean dose producing 50% inhibition compared with control parasite growth [id50] = 96 ng/ml, 0.32 microm), but showed no inhibition against the several t. cruzi and t. rang ... | 1997 | 9347954 |
| 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 |
| evolution of the genus leishmania revealed by comparison of dna and rna polymerase gene sequences. | previous hypotheses of leishmania evolution are undermined by limitations in the phylogenetic reconstruction method employed or due to the omission of key parasites. in this experiment, sequences of the gene encoding the dna polymerase alpha catalytic polypeptide (pola) were analysed phylogenetically in combination with those encoding the rna polymerase ii largest subunit gene (rpoiils) to infer a comprehensive phylogeny of leishmania. nineteen species of parasites were studied, comprising repre ... | 1997 | 9364962 |
| scid mice reconstituted with il-4-deficient lymphocytes, but not immunocompetent lymphocytes, are resistant to cutaneous leishmaniasis. | to characterize the roles of lymphoid- and non-lymphoid-derived il-4 during cutaneous infection with leishmania mexicana, the disease was monitored in scid mice reconstituted with splenocytes from either immunocompetent balb/c mice or il-4-deficient balb/c mice. whereas following s.c. infection with l. mexicana no lesion growth was observed in balb/c il-4(-/-) mice and lesion growth was significantly inhibited in scid mice, rapid initial lesion growth occurred in both scid il-4(+/+) and scid il- ... | 1997 | 9366428 |
| secreted proteophosphoglycan of leishmania mexicana amastigotes activates complement by triggering the mannan binding lectin pathway. | cutaneous lesions induced by infection of mice with the protozoan parasite, leishmania mexicana, contain abundant amounts of a high molecular mass proteophosphoglycan (ppg), which is secreted by the amastigote stage residing in phagolysosomes of macrophages and can then be released into the tissue upon rupture of the infected cells. amastigote ppg forms sausage-shaped but soluble particles and belongs to a novel class of serine-rich proteins that are extensively o-glycosylated by phosphooligosac ... | 1997 | 9368624 |
| efflux systems and increased trypanothione levels in arsenite-resistant leishmania. | the mechanism of resistance to the metal arsenite has been studied and compared in l. mexicana, l. tropica, and l. tarentolae selected in a step by step manner for arsenite resistance. amplification of the abc transporter gene pgpa was found to be a frequent resistance mechanism in all species. transfection of pgpa genes into different species indicated that both the origin of the pgpa gene and the recipient strain into which the gene is transfected seem important for resistance. an increase in ... | 1997 | 9371094 |
| non-ulcerative cutaneous leishmaniasis in honduras fails to respond to topical paromomycin. | a double-'blind', placebo-controlled trial of topical therapy with 15% paromomycin (aminosidine) and 10% urea in white paraffin was carried out on 53 patients with non-ulcerating cutaneous leishmaniasis in honduras. although the treatment was not effective, several unexpected findings emerged from the trial. leishmania mexicana was found to be the cause of many of the skin lesions in one of the 2 study sites. these lesions were clinically indistinguishable from those caused by l. chagasi, the ae ... | 1997 | 9373659 |