| infection of mouse macrophages in vitro by sandfly-derived promastigotes of leishmania mexicana amazonensis. | | 1981 | 7324121 |
| leishmaniasis in brazil: xv. biochemical distinction of leishmania mexicana amazonensis, l. braziliensis braziliensis and l. braziliensis guyanensis--aetiological agents of cutaneous leishmaniasis in the amazon basin of brazil. | enzymic profiles of the three known agents of human cutaneous leishmaniasis in the lower amazon region are compared. of 14 enzymes, 10 (asat, alat, gpi, g5pd, mdh, acon, pep, hk, mpi and acp) differentiate leishmania mexicana amazonensis from l. braziliensis braziliensis or l. braziliensis guyanensis: this supports their taxonomic status as distinct species. in contrast, only slight mobility differences of four enzymes (asat, alat, pgm, mpi) separate l. b. braziliensis and l. b. guyanensis, whic ... | 1981 | 7324127 |
| leishmaniasis in brazil: xvi. isolation and identification of leishmania species from sandflies, wild mammals and man in north para state, with particular reference to l. braziliensis guyanensis causative agent of "pian-bois". | a total of 125 wild mammals (14 different species) were examined for evidence of infection with leishmania in an area of primary forest highly endemic for "pian-bois", due to leishmania braziliensis guyanensis, in north pará state, brazil. parasites isolated were characterized biologically, and biochemically on enzymic profiles. l. b. guyanensis was isolated from the viscera of one lesser anteater (tamandua tetradactyla) and one opossum (didelphis marsupialis), and the skin of one rodent (proech ... | 1981 | 7324128 |
| the opossum, didelphis marsupialis (marsupialia: didelphidae), as a reservoir host of leishmania braziliensis guyanensis in the amazon basin of brazil. | a total of 52 opossums (six species) were examined for evidence of infection with leishmania in three different areas of forest near manaus, amazonas state, brazil. no infections were detected in 27 opossums from a region of relatively undisturbed forest, including specimens of didelphis marsupialis (18); metachirus nudicaudatus (four); monodelphis brevicaudata (one); marmosa cinerea (two); m. murina (one) and m. parvidens (one). of 15 d. marsupialis captured from a biological reserve, much dist ... | 1981 | 7324129 |
| leishmania mexicana amazonensis: attachment to the membrane of the phagocytic vacuole of macrophages in vivo. | intracellular forms of leishmania mexicana amazonensis divide inside the phagocytic vacuole of macrophages. some parasites attach to the membrane of the phagocytic vacuole while others remain free in the vacuole. examination of thin sections of the attachment region by electron microscopy revealed a space of 2 nm between the membrane of the phagocytic vacuole and the plasma membrane of the parasite. freeze-fracture replicas showed an array of intramembranous particles in some areas of the parasi ... | 1981 | 7324540 |
| some methods for the enzymic characterization of latin-american leishmania with particular reference to leishmania mexicana amazonensis and subspecies of leishmania hertigi. | 30 brazilian stocks of leishmania mexicana amazonensis and 13 stocks of subspecies of leishmania hertigi were characterized by starch-gel electrophoresis, using 18 enzymes selected from a total of 36 investigated. l. m. amazonensis was separable from subspecies of l. hertigi by enzymic profiles of 11 enzymes. the l. m. amazonensis stocks, which were from a wide range of hosts in a large geographical area, were enzymically extremely homogeneous, and could only be subdivided on two enzymes; sub-gr ... | 1980 | 7385303 |
| human cutaneous lieshmania in a mouse macrophage line: propagation and isolation of intracellular parasites. | a mouse macrophage line, j774g8, supports continuous and prolific intracellular growth of leishmania mexicana amazonensis, the etiological agent of a south american cutaneous leishmaniasis. the intracellular parasites from these infected cultures can be isolated with high recovery rate and purity by simple percoll gradient centrifugation. | 1980 | 7403880 |
| improved leishmanicidal effect of phosphorotioate antisense oligonucleotides by ldl-mediated delivery. | we have designed antisense oligonucleotides that can interact with lipoproteins in order to use them as vectors to facilitate the uptake by those cells expressing the corresponding receptor. phosphorothioate (ps) oligonucleotides were linked at the 5' end to a palmityl group giving rise to pspal conjugates. such a modification enables the oligonucleotide to form a stable non-covalent complex with low density lipoproteins (ldl) through hydrophobic interactions. the antisense effect of ldl-oligonu ... | 1995 | 7495868 |
| [histopathology of the localized form of cutaneous leishmaniasis caused by leishmania (leishmania) amazonensis]. | the microscopic changes found in the localized form of the human cutaneous leishmaniasis due to leishmania (leishmania) amazonensis are reported. in this form, less known than the diffuse one caused by the same species, the clinical manifestations are identical to those produced by other leishmania species of the subgenus viannia. there is, however, in the localized infection by l. (l.) amazonensis, a peculiar feature, only recently discovered: about 50% of the affected individuals are montenegr ... | 1994 | 7569614 |
| 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 |
| 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 |
| 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 |
| fructose 2,6 bisphosphate promotes the monomer-tetramer conservation of leishmania mexicana amazonensis pyruvate kinase type two. | the enzyme pyruvate kinase of leishmania mexicana amazonensis presents two forms with different kinetic properties and behavior for the heterotrophic activator fructose 2,6 bisphosphate. pyruvate kinase 1, which is isolated as a tetramer, is inhibited by this metabolite. the second activity, pyruvate kinase 2, is activated by fructose 2,6 bisphosphate, which promotes the monomer-tetramer conversion of this enzyme. | 1993 | 7670525 |
| identification of gtpase genes in the protozoa parasites trypanosoma cruzi and leishmania amazonensis. | a pcr based assay was designed in order to amplify putative ras gene sequences of the gtpase superfamily eventually present in leishmania amazonensis and trypanosoma cruzi. a set of primers corresponding to the conserved motifs g1 and g3 of the gtp binding proteins was synthesized. sequencing of six pcr products (three from leishmania and three from trypanosoma) identified, however, two other different gtpases. the 270 bp l. amazonensis clone, plef-11, shared an amino acid identity of around 80% ... | 1993 | 7670542 |
| differential expression of the plasma membrane mg2+ atpase and ca2+ atpase activity during adhesion and interiorization of leishmania amazonensis in fibroblasts in vitro. | with ultrastructural cytochemistry we localized the activity of the plasma membrane enzyme markers mg2+ atpase and ca2+ atpase during the interaction between leishmania amazonensis and in vitro primary culture fibroblasts. the expression of the enzymes was followed during the parasite adhesion and its interiorization. after the interiorization step, a striking difference was seen between the two enzymes studied when the parasite was found within the parasitophorous vacuole in the fibroblast cyto ... | 1995 | 7671216 |
| glycosphingolipid antigens of leishmania (leishmania) amazonensis amastigotes identified by use of a monoclonal antibody. | monoclonal antibodies directed against leishmania (leishmania) amazonensis amastigotes were produced. one monoclonal antibody (1c3) selected by indirect immunofluorescence reacted with both amastigotes and promastigotes of l. (l.) amazonensis. glycolipid extraction from l. (l.) amazonensis amastigotes and separation by high-performance thin-layer chromatography followed by immunoblotting demonstrated that 1c3 reacts with two glycosphingolipids which migrate chromatographically similarly to ceram ... | 1993 | 7683002 |
| fusion between large phagocytic vesicles: targeting of yeast and other particulates to phagolysosomes that shelter the bacterium coxiella burnetii or the protozoan leishmania amazonensis in chinese hamster ovary cells. | this report examines the fusion of phagocytic vesicles with the large phagolysosome-like vacuoles induced in chinese hamster ovary cells by the bacterium coxiella burnetti or the protozoan flagellate leishmania amazonensis. infection by these organisms is compatible with cell survival and multiplication. fusion was inferred from the transfer of microscopically identifiable particles from donor to target vesicles. donor vesicles contained heat-killed yeast, zymosan, beta-glucan or latex beads tak ... | 1994 | 7699006 |
| spontaneous regional healing of extensive skin lesions in diffuse cutaneous leishmaniasis (dcl). | the authors report a case of diffuse cutaneous leishmaniasis, with longstanding evolution and presenting with diffuse infiltrated lesions rich in amastigotes in the absence of mucosal involvement. in situ characterization with monoclonal antibodies revealed leishmania amazonensis. large regional lesions have presented spontaneous healing without specific therapy. considering that dcl presents with a defect in the cellular immune response, this fact demonstrate that this patient may develop a reg ... | 1995 | 7724867 |
| cytotoxicity in human mucosal and cutaneous leishmaniasis. | cd8+ t cells and lysis of parasitized macrophages seem to be important in the resistance to murine leishmaniasis. in the present study, we evaluated peripheral blood mononuclear cell (pbmc) from patients with either cutaneous (cl) or mucosal (ml) leishmaniasis in cell lysis assays using 51-cr-labeled daudi or k562 cells, or autologous antigen-pulsed macrophages as targets. results are reported as lytic units (number of cells required for 30% lysis) per million pbmc. exposure of patient pbmc (n = ... | 1995 | 7731732 |
| genetic rescue of surface metalloproteinase (gp63)-deficiency in leishmania amazonensis variants increases their infection of macrophages at the early phase. | | 1994 | 7808483 |
| 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 |
| the biosynthesis, processing, and immunolocalization of leishmania pifanoi amastigote cysteine proteinases. | biosynthesis, enzymatic processing, and immunocytochemical localization of an abundant developmentally regulated cysteine proteinase of leishmania pifanoi, lpcys2, were investigated employing axenic cultured amastigotes and monoclonal antibodies specifically recognizing either the mature proteinase or the carboxy-terminal extension domain. pulse labeling and protein sequence data indicated that a 45-kda precursor is processed to a 40-kda intermediate, which is further cleaved to generate the 27- ... | 1994 | 7891736 |
| leishmania amazonensis: sensitivity of different promastigote morphotypes to salivary gland homogenates of the sand fly lutzomyia longipalpis. | we have recently demonstrated that lutzomyia longipalpis salivary gland homogenates (sgh) inhibited the multiplication of leishmania promastigotes in vitro. the present work shows that leishmania amazonensis sensitivity to sgh is correlated to the phase of promastigote in vitro growth and can be decreased by the addition of hemin to the culture medium. the possible relevance of these in vitro results is discussed in relation to the development of leishmania parasites within their sand fly vector ... | 1995 | 7895828 |
| effect of in vivo depletion of cd4+ t cells on experimental infection of susceptible balb/c mice with leishmania amazonensis. | the role played by cd4+ t lymphocytes in susceptible balb/c mice infected with leishmania amazonensis was investigated. depletion of cd4+ t cells was achieved in experimentally infected mice by means of treatment with anti-cd4 monoclonal antibody (mab), resulting in significant reductions in the size of lesions and in mortality when compared with control animals. moreover, the parasite load in the depleted mice, as quantified by limiting dilution analysis, was about 10-times lower than in the co ... | 1994 | 7911268 |
| detection of ubiquinone in parasitic and free-living protozoa, including species devoid of mitochondria. | ubiquinone (coenzyme q, coq) was analyzed and individual homologues quantified in 11 species of parasitic and free-living protozoa by a combination of thin-layer chromatography and high performance liquid chromatography. fast atom bombardment ionization-mass spectrometry was used for the first time to confirm the identity of the fractionated coq homologues and proved to be a fast, gentle and convenient method for ubiquinone identification. ubiquinone was detected in all organisms including those ... | 1994 | 7969263 |
| functional analysis of cis-acting dna elements required for expression of the sl rna gene in the parasitic protozoan leishmania amazonensis. | dna sequences, that control expression of the spliced leader (sl) rna gene in the parasitic protozoan leishmania amazonensis, were mapped by block substitution mutagenesis. in the absence of a functional in vitro system for transcription, no promoter elements have yet been identified in this organism. we therefore developed an alternative in vivo approach, in which the sl rna gene was tagged and then subjected to a series of linker scanning mutations. each tagged and mutated sl rna construct was ... | 1994 | 8029000 |
| specific a+t-rich repetitive dna sequences in maxicircles from wildtype leishmania mexicana amazonensis and variants with dna amplification. | to explain the low cross-hybridization between kinetoplast dna maxicircles of leishmania parasites that show dna amplification and those of parasites without dna amplification, we isolated and cloned two maxicircle fragments, one specific to each group of parasites. the cloned fragment from wildtype l. m. amazonensis (mbpw94) and that from an arsenite-resistant variant with dna amplification (mpba29) hybridized only to maxicircles from parasites of the group from which the fragment was originall ... | 1994 | 8050523 |
| isomeric and quaternary properties of homogenous 33 kda protein from the venom of chelonus near curvimaculatus. | the 33,000 dalton venom protein of chelonus near curvimaculatus was characterized for structural properties of charge, quaternary associations, and relationship to polydnavirus encoded proteins. homogenous isoforms of the protein were isolated from the venom by sequential steps of 1) microdissection, 2) separation based on charge (mono-q column hplc or narrow-range electrofocusing), and 3) centrifugal filtration based on molecular weight using centricon microconcentrators. the purified protein d ... | 1994 | 8054662 |
| antisense phosphorothioate oligonucleotides: selective killing of the intracellular parasite leishmania amazonensis. | we targeted the mini-exon sequence, present at the 5' end of every mrna of the protozoan parasite leishmania amazonensis, by phosphorothioate oligonucleotides. a complementary 16-mer (16ps) was able to kill amastigotes--the intracellular stage of the parasite--in murine macrophages in culture. after 24 hr of incubation with 10 microm 16ps, about 30% infected macrophages were cured. the oligomer 16ps acted through antisense hybridization in a sequence-dependent way; no effect on parasites was obs ... | 1994 | 8058724 |
| identification of a putative pore-forming hemolysin active at acid ph in leishmania amazonensis. | several organisms, including the protozoa entamoeba histolytica and trypanosoma cruzi, have been shown to contain pore-forming proteins (pfp) thought to play a role in the pathogenesis of the diseases they generate. in the present report, we show that promastigotes of leishmania amazonensis express a hemolysin that appears to cause colloid-osmotic lysis, typical of pore formation. this hemolysin affects red blood cells of different species at 37 degrees c, but not at 0 degrees c, with maximum ac ... | 1994 | 8081268 |
| relative contribution of photo-addition, helper oligonucleotide and rnase h to the antisense effect of psoralen-oligonucleotide conjugates, on in vitro translation of leishmania mrnas. | we investigated the properties of two antisense oligonucleotides, 11 alpha pso and 14tmp, 11 and 14 nucleotides long, respectively, and conjugated to psoralen derivatives. these oligonucleotides were complementary to the mini-exon sequence of leishmania amazonensis. upon ultraviolet (uv) irradiation these oligomers were selectively cross-linked to dna or rna target sequences, either 14 or 35 nucleotides long. the yield of photo-addition was much lower on the longer targets than on the shorter on ... | 1994 | 8086483 |
| t cell response in murine leishmania mexicana amazonensis infection: production of interferon-gamma by cd8+ cells. | the immune response to leishmania major has been the subject of many investigations. however, leishmania includes many species with different clinical manifestations. in this report, we studied the t cell response to l. mexicana amazonensis, a new world species, in a murine model. we found that, similar to l. major, an old world species, resistant c57bl/6 mice produced a high level of ifn-gamma and a low level of il-4. conversely, susceptible balb/c mice produced a much lower level of ifn-gamma ... | 1993 | 8097471 |
| antigen presentation capacity of murine macrophages infected with leishmania amazonensis amastigotes. | leishmania-infected m phi are potential candidates for the presentation of parasite ag to leishmania-specific cd4+ t lymphocytes. to assess whether infected cells could function as apc, we examined the ability of bone marrow-derived m phi infected with leishmania amazonensis amastigotes to stimulate various cd4+, l-ad- or l-ed-restricted t-cell hybridomas specific for the bacteriophage lambda repressor cl protein, the human chorionic gonadotropin or ova. a reduced capacity of infected m phi to p ... | 1993 | 8102156 |
| immunogold labeling and cerium cytochemistry of the enzyme ecto-5'-nucleotidase in promastigote forms of leishmania species. | we have applied both enzyme cytochemistry and immunological labeling techniques to characterize the enzyme 5'-nucleotidase (5'-nase), at the ultrastructural level, in promastigote forms of four leishmania species: leishmania amazonensis, leishmania mexicana, leishmania donovani and leishmania chagasi. the cerium phosphate staining was localized at the surface of the cell body, the flagellum and the flagellar pocket membranes of all the parasites studied. the immunogold labelling technique confir ... | 1993 | 8107602 |
| [disseminated cutaneous leishmaniasis due to leishmania viannia braziliensis in the state of maranhão, brazil]. | the authors describe a case of a patient from barreirinhas, ma with disseminated cutaneous leishmaniasis, who presented 58 lesions spread all over his body, with many different aspects, but ulcerative lesions were predominant. they discuss the difficulty of laboratory diagnosis in the beginning of the investigation and its therapeutics implications. the parasite isolated was identified as leishmania viannia braziliensis using monoclonal antibodies in the fluorescent antibody test. this form of t ... | 1993 | 8128071 |
| sequence and genomic organization of the hsp70 genes of leishmania amazonensis. | the sequence and genomic organization of hsp70 genes in leishmania amazonensis were examined. maps of overlapping cosmid clones revealed that seven l. amazonensis hsp70 genes are organized into a 24-kb locus containing 3.5-kb tandem repeats. cosmids covering a different chromosomal region indicated that an eighth hsp70 sequence is located at a distant site. southern blot data suggested the existence of additional hsp70 genes or pseudogenes. one complete 3.5-kb genomic repeat unit, including codi ... | 1993 | 8139614 |
| distribution of mhc class i and of mhc class ii molecules in macrophages infected with leishmania amazonensis. | macrophages, being apparently the only cells that in vivo allow the growth of the intracellular pathogen leishmania, are likely candidates to present antigens to leishmania-specific cd4+ and cd8+ t lymphocytes, known to be involved in the resolution or in the development of lesions induced by these parasites, and recognizing processed antigens bound to mhc class i and mhc class ii molecules, respectively. in the present study, we analysed by confocal microscopy and by immunoelectron microscopy t ... | 1994 | 8175924 |
| a heparin-binding activity on leishmania amastigotes which mediates adhesion to cellular proteoglycans. | the intracellular amastigote form of leishmania is responsible for the cell-to-cell spread of leishmania infection in the mammalian host. in this report, we identify a high-affinity, heparin-binding activity on the surface of the amastigote form of leishmania. amastigotes of leishmania amazonensis bound approximately 120,000 molecules of heparin per cell, with a kd of 8.8 x 10(-8) m. this heparin-binding activity mediates the adhesion of amastigotes to mammalian cells via heparan sulfate proteog ... | 1993 | 8227137 |
| reduced purine accumulation is encoded on an amplified dna in leishmania mexicana amazonensis resistant to toxic nucleosides. | nucleoside analogs are potential anti-leishmania agents. to better understand how these compounds might lose their effectiveness, leishmania were independently selected for resistance to inosine dialdehyde or tubercidin. each of the resistant cells exhibited resistance to inosine dialdehyde and tubercidin as well as to formycin b and allopurinol ribonucleoside. resistant cells had a greatly reduced capability of accumulating exogenous adenosine, guanosine, thymidine and guanine. this decreased a ... | 1993 | 8232410 |
| effect of macrophage infection by leishmania on the proliferation of an antigen-specific t-cell line, tpb1, to a non-parasite antigen. | the ability of leishmania mexicana amazonensis to inhibit antigen specific t-cell proliferation against a non-parasite polypeptide antigen, poly(ltyr, lglu)-poly(dlala)--poly(llys), was examined. infection of mouse peritoneal macrophages by promastigotes blocked the proliferation of the t-cell line, tpb1. this effect was correlated with the level of parasite infection, and the timing of macrophage infection and antigen addition. peritoneal macrophages from both balb/b and c57bl/6 mice showed red ... | 1993 | 8233564 |
| selection for arsenite resistance causes reversible changes in minicircle composition and kinetoplast organization in leishmania mexicana. | certain minor minicircle sequence classes in the kinetoplast dna (kdna) networks of arsenite- or tunicamycin-resistant leishmania mexicana amazonensis variants whose nuclear dna is amplified appear to be preferentially selected to replicate (s. t. lee, c. tarn, and k. p. chang, mol. biochem. parasitol. 58:187-204, 1993). these sequences replace the predominant wild-type minicircle sequences to become dominant species in the kdna network. the switch from wild-type-specific to variant-specific min ... | 1994 | 8264626 |
| an experimental model of the production of metastases in murine cutaneous leishmaniasis. | an experimental investigation into the influence of artificially induced trauma in the production of leishmanial metastatic lesions and into the possible role played by leishmania-reactive t cell populations in the metastatic process was carried out. trauma was induced by incising a small cut into the shaved rump of leishmania amazonensis-infected balb/c mice. ten days after the trauma, mice were killed to quantify the parasite load in the traumatic lesion or in the equivalent area in nontraumat ... | 1994 | 8308664 |
| induction of complement-sensitivity in leishmania amazonensis metacyclic promastigotes by protease treatment but not by specific antibodies. | | 1993 | 8327457 |
| cytostatic effect of lutzomyia longipalpis salivary gland homogenates on leishmania parasites. | salivary gland homogenates (sgh) of female lutzomyia longipalpis, in concentrations as small as 0.05 pairs of glands/ml, inhibit the in vitro multiplication of promastigotes of leishmania mexicana amazonensis. the effect seems to be cytostatic since promastigote viability 24 hr after exposure ranged from 55% to 100% in different experiments. the cells cultivated in the presence of sgh were characterized by a very slender shape, with cell bodies that were almost two times as long as controls. the ... | 1993 | 8333578 |
| recombinant vaccinia viruses expressing gp46/m-2 protect against leishmania infection. | leishmania is a genus of parasitic protozoa capable of causing a spectrum of human diseases. the gp46/m-2 membrane glycoprotein has been demonstrated in a murine model system to elicit a protective immune response against infection with leishmania amazonensis; in highly susceptible balb/c mice, immunization leads to significant protection against infection. in the present study, for induction of long-term immunological effects, two recombinant vaccinia viruses, derived from the wild type and att ... | 1993 | 8335366 |
| effects of sinefungin on growth and sterol composition of leishmania promastigotes. | the s-adenosylmethionine analogue sinefungin was tested in vitro against promastigotes of various strains of leishmania. the ic50 values for the leishmania mexicana, leishmania major, and leishmania donovani strains used were of the order of 10 ng/ml but the leishmania amazonensis strain tested was more resistant to the drug, the ic50 value being 6 micrograms/ml. sterol profiles, in which 24-alkyl (c28) sterols predominated, were relatively unaffected by sinefungin. incorporation of label derive ... | 1993 | 8375483 |
| antigen-reactive gamma delta t cells in human leishmaniasis. | the importance of ag-specific gamma delta t lymphocytes in human immune responses to pathogenic organisms is unknown. in the present study the expression of gamma delta tcr on t lymphocytes from patients with cutaneous, mucosal, or visceral leishmaniasis was examined. all of these patient groups had elevated levels of gamma delta t cells in peripheral blood. patients' gamma delta t cells included cd8+ as well as null cells. the percentage of t cells expressing gamma delta tcr was increased signi ... | 1993 | 8376802 |
| characterization of the switch of kinetoplast dna minicircle dominance during development and reversion of drug resistance in leishmania. | to characterize the differences between kdna minicircles of drug-resistant leishmania mexicana amazonensis variants that show nuclear dna amplification and minicircles of variants without nuclear dna amplification, we sequenced minicircles from repeatedly cloned parasites. the dominant minicircles from arsenite- and tunicamycin-resistant parasites with dna amplification were found to preexist as minor conserved divergent classes in parental wild-type cells. these classes shared very limited simi ... | 1993 | 8386802 |
| molecular cloning and characterization of a 42-kda protein phosphatase of leishmania chagasi. | using rabbit serum raised against a potent t cell-stimulating antigen fraction of leishmania chagasi promastigotes, we have cloned and expressed the leishmania type 2c serine/threonine protein phosphatase, lcpp2c. lcpp2c was shown to be present as a 42-kda protein in both the infective promastigote and tissue amastigote stages of l. chagasi and leishmania amazonensis. dna hybridization studies established the close conservation of lcpp2c among eight of eight geographically diverse species of lei ... | 1993 | 8394331 |
| isolation of two pyruvate kinase activities in the parasitic protozoan leishmania mexicana amazonensis. | using phosphocellulose affinity chromatography we were able to separate two pyruvate kinase (ec 2.7.1.40) activities in the parasitic protozoan leishmania mexicana amazonesis. one activity (pyk1) showed hyperbolic kinetics and was decreased by fructose 2,6-bisphosphate, whereas the second activity (pyk2) showed sigmoidal kinetics for the substrate phosphoenolpyruvate and was activated by fructose 2,6-bisphosphate. molecular sieve chromatography (sephacryl s-400) of pyk1 produced a single peak of ... | 1993 | 8424681 |
| leishmania mexicana amazonensis: effect of heat shock on the spliced leader rna and its ribonucleoprotein particle sl rnp. | trypanosomatid parasites of the genus leishmania experience a temperature shift from 22-38 degrees c to 33-37 degrees c while being transmitted from the invertebrate vector to the mammalian host. expression of many protein-coding genes in protozoan parasites that cycle between two hosts have been shown to be thermosensitive, and temperature changes most probably serve as a major regulatory factor during stage differentiation. we present here our studies on effects of physiological temperature sh ... | 1993 | 8467899 |
| cutaneous leishmaniasis in mast cell-deficient w/wv mice. | genetically mast cell-deficient w/wv mice infected with leishmania amazonensis showed progressive development of ulcerative skin lesions. however, no significant differences between the w/wv mice and the normal littermates with respect to size of the lesions, anti-leishmania immunoglobulin e antibody, and the number of eosinophils accumulated in the lesions were observed. | 1993 | 8478118 |
| 2-substituted quinoline alkaloids as potential antileishmanial drugs. | ten 2-substituted quinoline alkaloids isolated from a plant used for treatment of new world cutaneous leishmaniasis have antileishmanial in vitro activities against the extracellular forms of leishmania spp. balb/c mice infected with leishmania amazonensis ph8 or h-142 or leishmania venezuelensis were treated 1 day after the parasitic infection with a quinoline alkaloid (100 mg/kg of body weight per day) or with reference drug n-methylglucamine antimonate (glucantime) (56 mg of pentavalent antim ... | 1993 | 8494383 |
| intergenic sequences from the heat-shock protein 83-encoding gene cluster in leishmania mexicana amazonensis promote and regulate reporter gene expression in transfected parasites. | regulation of expression from hsp83 gene cluster encoding heat-shock protein (hsp) 83 of the protozoan parasite leishmania mexicana amazonensis (l.m.a) was examined. the first gene from this cluster, along with 8 kb of flanking sequences, was cloned, and intergenic region (ir) sequences were found upstream from the cluster. l.m.a. parasites were electroporated with a plasmid (pici) in which the chloramphenicol acetyltransferase (cat)-encoding gene (cat) was cloned between two irs derived from an ... | 1993 | 8500758 |
| antisense effect of oligodeoxynucleotides complementary to the mini-exon sequence of the protozoan parasite leishmania amazonensis. | we have targeted the mini-exon of leishmania amazonensis, the sequence present at the 5' end of every mrna of this protozoan parasite, with a complementary 12-mer, either unmodified (12 le ii) or linked to an acridine derivative (12 le ii acr). physical measurements performed either in solution or on nitrocellulose filters showed that the two oligomers exhibited the same affinity for both dna and rna target sequences. furthermore, the two oligomers 12 le ii and 12 le ii acr inhibited in vitro tr ... | 1993 | 8504176 |
| immune responses associated with susceptibility of c57bl/10 mice to leishmania amazonensis. | leishmaniae are protozoans which, depending upon both the host and parasite species, can cause either a healing or nonhealing infection. while c57bl/10 mice are able to heal following infection with leishmania major, they fail to heal following infection with leishmania amazonensis. in order to address the role of th1 and th2 cell responses in the outcome of these infections in c57bl/10 mice, gamma interferon (ifn-gamma) and interleukin-4 (il-4) production was assessed. while cells from l. major ... | 1993 | 8514400 |
| herbicides to curb human parasitic infections: in vitro and in vivo effects of trifluralin on the trypanosomatid protozoans. | leishmaniasis is a major tropical disease for which current chemotherapies, pentavalent antimonials, are inadequate and cause severe side effects. it has been reported that trifluralin, a microtubule-disrupting herbicide, is inhibitory to leishmania amazonensis. in this study, the in vitro effect of trifluralin on different species of trypanosomatid protozoans was determined. in addition to l. amazonensis, trifluralin is effective against leishmania major and leishmania tropica, which cause cuta ... | 1993 | 8516314 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |