| regulation of putrescine uptake in leishmania mexicana promastigotes. | putrescine uptake of leishmania mexicana promastigotes is tightly regulated by polyamine intracellular concentrations. this uptake, markedly stimulated after parasite treatment with alpha-difluoromethylornithine (dfmo) for 48 to 72 hrs., was strongly repressed by exposure of leishmania cultures to exogenous putrescine or its derivative 1,4-dimethylputrescine. in contrast, spermidine, spermine, diaminopropane and cadaverine were unable to decrease putrescine transport. both, the uptake induction ... | 1994 | 7849558 |
| infection of balb/c, c57b1/6 mice and f1 hybrid cb6f1 mice with strains of leishmania mexicana isolated from mexican patients with localized or diffuse cutaneous leishmaniasis. | mice from the syngeneic strains balb/c, c57b1/6 and (balb/cxc57b1/6)f1 hybrids (cb6f1) were infected in the footpad with six different strains of leishmania mexicana mexicana isolated from mexican patients. three leishmania strains were isolated from patients with localized cutaneous leishmaniasis (lcl, the benign form of the disease) and three from patients with diffuse cutaneous leishmaniasis (dcl, the malignant form of the disease). in balb/c mice, four leishmania strains showed a sustained f ... | 1994 | 7858398 |
| identification of a 94-kilodalton antigen on leishmania promastigote forms and its specific recognition in human and canine visceral leishmaniasis. | we have analysed by immunoblotting sera from humans and dogs with visceral leishmaniasis, from the old world as well as the new. when lysates of promastigotes are used as antigens, antibodies against a 94 kda leishmania component are detected, regardless of the age and geographical origin of the patient, the serum antibody titre as measured by indirect immunofluorescence, and the number of arcs in counterimmunoelectrophoresis. low dilutions of sera from patients with old and new world cutaneous ... | 1994 | 7862466 |
| distribution of parasite cysteine proteinases in lesions of mice infected with leishmania mexicana amastigotes. | it is well established that leishmania mexicana amastigotes contain large amounts of cysteine proteinases in their extended lysosomes. in this study it is shown that the cell-free supernatant of homogenized lesion tissue from infected mice contains large amounts of acid proteinases. the majority of this enzymatic activity also corresponds to cysteine proteinases from l. mexicana amastigotes. immunoelectron microscopy of mouse lesion sections suggests, that frequently amastigotes lyse and release ... | 1994 | 7870124 |
| subcellular distribution and characterization of glucosephosphate isomerase in leishmania mexicana mexicana. | the glycolytic enzyme glucosephosphate isomerase (pgi) is present in two different cell compartments of leishmania mexicana promastigotes; more than 90% of the activity was detected in the cytosol, the remainder in glycosomes. this subcellular distribution contrasts with that in trypanosoma brucei, in which the enzyme activity has been mainly located in the glycosomes. pgi was partially purified from l. mexicana cell extracts. throughout the purification procedure only one single pgi activity co ... | 1994 | 7870131 |
| a comparative study of the utilization of ether- and ester-linked phospholipid-containing liposomes by j774.e1 macrophage cell-line infected with leishmania mexicana mexicana amastigotes. | the macrophage cell-line j774.e1 and leishmania m. mexicana infection was used to investigate the uptake of liposomes, which differed in their bulk phospholipid: ester- or ether-analogue of phosphatydilcholine (pc). the receptor-mediated uptake of both species of liposomes, containing native or acetylated ldl as ligands was also evaluated. uninfected and infected j774.e1 cell-line accumulated more ester- and ether-liposomes alone than mixed type (50:50, ester/ether). the utilization was signific ... | 1994 | 7883247 |
| leishmania mexicana: the influence of slightly elevated temperature on the ultrastructure of axenic amastigote-like forms. | | 1994 | 7886041 |
| aminosidine (paromomycin) versus sodium stibogluconate for the treatment of american cutaneous leishmaniasis. | the efficacy of aminosidine was compared with sodium stibogluconate in an open, randomized study of parasitologically-proven cutaneous leishmaniasis in belize. aminosidine, 14 mg/kg/d (max. 1 g daily) for 20 d, healed 10 of 17 lesions and sodium stibogluconate, 20 mg/kg/d for 20 d, healed 15 of 17 lesions. lesions caused by leishmania braziliensis were relatively unresponsive to aminosidine. aminosidine was well tolerated and toxicity was not observed. sodium stibogluconate was not well tolerate ... | 1994 | 7886779 |
| immune response in healthy volunteers vaccinated with bcg plus killed leishmanial promastigotes: antibody responses to mycobacterial and leishmanial antigens. | antibody (igg) responses to mycobacterial (bcg; ppd; mycobacterium leprae soluble antigen, mlsa) and leishmanial (leishmania mexicana lv4) antigens were measured in 208 initially ppd and leishmanin skin-test negative volunteers divided into four vaccine groups as follows: 68 received bcg plus killed promastigotes (group a), 47 received bcg alone (group b), 47 received killed promastigotes alone (group c), and 46 formed the diluent control (placebo, group d). three vaccine doses were administered ... | 1994 | 7887018 |
| sex-determined susceptibility and differential ifn-gamma and tnf-alpha mrna expression in dba/2 mice infected with leishmania mexicana. | female dba/2 mice have been shown to be relatively resistant to infection with leishmania mexicana when compared with male mice. in order to determine the immunological basis behind this difference the draining lymph nodes from male and female dba/2 mice were excised and the rna extracted at different time-points following infection. following reverse transcription, the polymerase chain reaction (pcr) was used to identify mrna transcripts for interferon-gamma (ifn-gamma), tumour necrosis factor- ... | 1995 | 7890293 |
| inverted repeat structure and homologous sequences in the ld1 amplicons of leishmania spp. | in the parasitic trypanosomatids of the genus leishmania, novel circular (cd) and linear (ld) multicopy genetic elements arise de novo either spontaneously or as a result of drug selection. we report that the ld1 minichromosomes of l. donovani, l. major and l. mexicana (ranging in size from 180 to 230 kb) have an inverted repeat structure and contain homologous sequences located at similar distances from the telomere; one half of the chromosome being the mirror image of the other. they must ther ... | 1994 | 7891749 |
| 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 |
| course of leishmania infection in beta 2-microglobulin-deficient mice. | mice homozygous for a beta 2-microglobulin (beta 2-m) gene disruption lack the beta 2-m protein and are deficient in functional major histocompatibility complex class i (mhc i) molecules. the mutant mice have normal numbers of cd4+8- t helper cells but lack mhc i-directed cd4-8+ alpha/beta t cells. the beta 2-m mutant and wild-type mice were infected with leishmania major or l. mexicana, which cause cutaneous leishmaniasis in the old and new world, respectively. in both mutant and wild-type mice ... | 1993 | 7901152 |
| 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 |
| purification and characterization of the native and the recombinant leishmania mexicana glycosomal glyceraldehyde-3-phosphate dehydrogenase. | the gene coding for the glycosomal glyceraldehyde-3-phosphate dehydrogenase from leishmania mexicana has been cloned into vector pet3a and expressed as a soluble and active protein in escherichia coli bl21(de3) in which the endogenous gene has been inactivated by mutation. the recombinant enzyme was purified to near homogeneity by ammonium sulphate precipitation, followed by hydrophobic and cation-exchange chromatography. from a 1-l culture of e. coli cells, 25 mg purified protein was obtained w ... | 1994 | 7925431 |
| o- and n-glycosylation of the leishmania mexicana-secreted acid phosphatase. characterization of a new class of phosphoserine-linked glycans. | the protozoan parasite leishmania mexicana secretes a heavily glycosylated 100-kda acid phosphatase (sap) which is associated with one or more polydisperse proteophosphoglycans. most of the glycans in this complex were released using mild acid hydrolysis conditions that preferentially cleave phosphodiester linkages. the released saccharides were shown to consist of monomeric mannose and a series of neutral and phosphorylated glycans by dionex high performance liquid chromatography, methylation a ... | 1994 | 7929059 |
| selective inhibition of trypanosomal glyceraldehyde-3-phosphate dehydrogenase by protein structure-based design: toward new drugs for the treatment of sleeping sickness. | within the framework of a project aimed at rational design of drugs against diseases caused by trypanosomes and related hemoflagellate parasites, selective inhibitors of trypanosomal glycolysis were designed, synthesized, and tested. the design was based upon the crystallographically determined structures of the nad:glyceraldehyde-3-phosphate dehydrogenase complexes of humans and trypanosoma brucei, the causative agent of sleeping sickness. after one design cycle, using the adenosine part of the ... | 1994 | 7932587 |
| infection of human monocytes by leishmania results in a defective oxidative burst. | the effect of infection by prototypes from the three major species of leishmania on the oxidative burst of human mononuclear phagocytes in culture was examined. the presence of intracellular parasites of the three species, l.major, l.donovani and l.mexicana decreased hydrogen peroxide (h2o2) and superoxide anion (o2-) production. this was particularly apparent when infected cells were compared to control monocytes following treatment with ifn-gamma. nitroblue tetrazolium (nbt) reduction by monoc ... | 1994 | 7947230 |
| immune response in healthy volunteers vaccinated with killed leishmanial promastigotes plus bcg. i: skin-test reactivity, t-cell proliferation and interferon-gamma production. | this study reports the results of a vaccine trial established to study the cellular immune responses in vivo (skin-test reactivity) and in vitro (t-cell proliferation and interferon-gamma production) to both leishmanial and mycobacterial antigens following vaccination of healthy volunteers from a leishmaniasis-endemic area with killed leishmanial promastigotes, with or without bcg (bacille calmètte-guerin). skin tests were performed using purified protein derivative of tuberculin (ppd) and leish ... | 1994 | 7975845 |
| structure-function analysis of antimicrotubule dinitroanilines against promastigotes of the parasitic protozoan leishmania mexicana. | | 1994 | 7979313 |
| an episome of trypanosoma brucei can exist as an extrachromosomal element in a broad range of trypanosomatids but shows different requirements for stable replication. | | 1994 | 7984179 |
| atomic absorption spectrophotometric measurement of intracellular arsenite in arsenite-resistant leishmania. | | 1994 | 7984181 |
| coexistence of two species of leishmania in the digestive tract of the vector lutzomyia ovallesi. | leishmania isolated from the digestive tract of a naturally infected lutzomyia ovallesi sand fly were cultured in blood agar for rapid growth, cloning, and subsequent identification through schizodeme analysis, dot-blot hybridization, use of monoclonal antibodies with various specificities and absorbed polyclonal antibodies. twenty-three clones isolated from the primary culture were identified. the results showed that parasites belonging to some clones corresponded to the l. mexicana complex, wh ... | 1994 | 7985760 |
| cloning and sequence analysis of the gene encoding pyruvate kinase in trypanoplasma borelli. | the gene coding for pyruvate kinase in trypanoplasma borelli has been cloned and characterized. a single gene copy was found with an open reading frame for a polypeptide of 496 amino acids and a molecular mass of 54337. the deduced amino acid sequence has a calculated net charge of -3. comparison of the sequence with those of pyruvate kinases from members of the family trypanosomatidae revealed amino acid identities of 58.4-61.5%, and, to some extent, conservation of residues supposed to be invo ... | 1994 | 8003008 |
| null mutants for the lmcpa cysteine proteinase gene in leishmania mexicana. | the parasitic protozoon leishmania mexicana possesses an abundance of developmentally regulated cathepsin l-like cysteine proteinases expressed at highest levels in amastigotes. we recently characterised lmcpa, a single-copy gene encoding one such proteinase, lmcpa, which differs from other homologues by possessing a 3-amino-acid insertion at the amino terminal of the predicted mature proteinase. to investigate the role of lmcpa in l. mexicana, we used gene-targeting of promastigotes with hygrom ... | 1994 | 8008019 |
| 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 |
| expression of cysteine proteinases by metacyclic promastigotes of leishmania mexicana. | the expression of cysteine proteinases by metacyclic promastigotes of leishmania mexicana was investigated using gelatin polyacrylamide gel electrophoresis. two prominent bands were detected which distinguished metacyclics from multiplicative promastigotes, lacking detectable cysteine proteinase activity, and amastigotes, with a distinct banding pattern composed of multiple enzymes. a correlation between relative activity of the metacyclic-specific bands and the prevalence of metacyclics was fou ... | 1994 | 8049682 |
| 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 |
| 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 |
| effect of ketoconazole on lethal action of amphotericin b on leishmania mexicana promastigotes. | the effect of ergosterol depletion by ketoconazole on the leishmanicidal activity of the pore-forming antibiotic amphotericin b (amb) was investigated. leishmania mexicana promastigotes were lysed within minutes by the addition of micromolar concentrations of amb (0.5 microm) but became insensitive to amb after growth in the presence of ketoconazole (0.25 microm, 90 h). lipid chromatographic analysis indicated that under such conditions, ketoconazole depleted the major leishmania sterols, dehydr ... | 1994 | 8067741 |
| successful treatment of cutaneous leishmaniasis with allopurinol after failure of treatment with ketoconazole. | treatment of persistent leishmaniasis with oral agents has received increasing attention, although the optimal agent for use in all settings has not been determined. this report describes a patient with persistent cutaneous infection due to leishmania mexicana mexicana who apparently responded to therapy with allopurinol after treatment with a course of ketoconazole failed. in vitro testing of pre- and posttreatment isolates from the wound did not demonstrate the development of resistance to ket ... | 1994 | 8075279 |
| [the therapy of cutaneous and mucocutaneous leishmaniasis]. | | 1994 | 8076505 |
| pyruvate kinase of leishmania mexicana mexicana. cloning and analysis of the gene, overexpression in escherichia coli and characterization of the enzyme. | leishmania mexicana mexicana contains two tandemly arranged genes for pyruvate kinase (pyk). the 5' located gene codes for a polypeptide with a molecular mass of 54,370. the calculated net charge and isoelectric point of the polypeptide are -6 and 6.5, respectively. its amino-acid sequence is 73.7% identical to that of the trypanosoma brucei pyk and 46.4-49.8% to the enzyme of mammalian cells. the second gene appears not to be functional, because its 5' and 3' extremities have undergone recombin ... | 1994 | 8078522 |
| expression of heat shock protein 83 in leishmania is regulated post-transcriptionally. | mechanisms for regulation of heat shock protein (hsp) 83 expression were examined in leishmania amazonesis. transcripts of hsp83 accumulated upon temperature elevation; however, in contrast to non-protozoan eukaryotes (i.e. drosophila, yeast, avian or human cells), no transcriptional activation was observed. the increase in the hsp83 mrna level evolved from temperature induced variations in mrna turn-over: the hsp83 transcript was rapidly degraded at normal temperatures, whereas heat shock led t ... | 1994 | 8078527 |
| 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 |
| cross-reactivity studies and differential serodiagnosis of human infections caused by trypanosoma cruzi and leishmania spp; use of immunoblotting and elisa with a purified antigen (ag163b6). | results of our studies on the reactivity of chagasic and leishmaniasic sera with the purified t. cruzi-specific antigen 163b6, as assessed by elisa, and with complex antigenic mixtures from t. cruzi and leishmania mexicana, by immunoblotting, are presented here. our objective was to identify the antigens responsible for the exhibited cross-reactivity between trypanosomiasis and leishmaniasis, and to find a specific reactivity pattern corresponding to each parasitosis. in spite of the high cross- ... | 1994 | 8082296 |
| [intracellular calcium homeostasis. calmodulin and ca(2+)-atpase of the plasma membrane of trypanosomatids]. | the intracellular ca2+ concentration in all eukaryotic cells so far studied is 4 orders of magnitude lower than in the extracellular milieu. in trypanosomatids, the intracellular concentration of this cation is around 50 nm, even lower than in higher eukaryotics. this differential concentration is maintained by diverse transport systems at the plasma membrane level and at certain intracellular organelles. in the case of trypanosomatids it have been identified the presence of an electrophoretic u ... | 1993 | 8085408 |
| 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 |
| increased expression of proinflammatory cytokines in chronic lesions of human cutaneous leishmaniasis. | the nature of the host cellular immune response largely determines the expression of disease following infection with the intracellular protozoans leishmania spp. in experimental animals control and resolution of infection are mediated by gamma interferon and tumor necrosis factor alpha (tnf-alpha), whereas disease progression is associated with the production of interleukin 4 (il-4), il-5, il-10, and transforming growth factor beta (tgf-beta). we have analyzed the profile of cytokine gene expre ... | 1994 | 8112853 |
| relationships between cell surface protease and acid phosphatase activities of leishmania promastigote. | a correlation between the ratio of the cell surface protease activity to phosphatase activity and the complexity of the pattern of cell surface exposed polypeptides of leishmania promastigotes was demonstrated for various strains grown under similar conditions. the ratio of the cell surface protease activity to acid phosphatase activity was high for l. major and l.b. panamensis and it correlates with the expression of a single polypeptide of 63 kda on their cell surface. intermediate and lower r ... | 1993 | 8114687 |
| triose-phosphate isomerase of leishmania mexicana mexicana. cloning and characterization of the gene, overexpression in escherichia coli and analysis of the protein. | the gene of triose-phosphate isomerase in leishmania mexicana has been cloned and characterized. the gene encodes a polypeptide of 251 amino acids, with a calculated molecular mass of 27,561 da and a net charge of +2. only one gene could be detected, although the enzyme is present in two different compartments of the cell, in microbody-like organelles called glycosomes and in the cytosol. the primary structure of the enzyme has many features in common with that of triose-phosphate isomerase in t ... | 1994 | 8125090 |
| cathepsin b-like cysteine proteases of leishmania mexicana. | a group of leishmania mexicana cysteine proteases that differ from those previously found in this protozoon are described. the enzymes characteristically have a preference for peptidyl substrates with a phenylalanyl-valyl-arginyl moiety, do not hydrolyse gelatin in substrate-sodium dodecyl sulphate polyacrylamide gels, are stimulated by thiol-reducing agents and are sensitive to inhibitors specific for cysteine proteases. they have unusual solubility properties that indicate that the enzymes are ... | 1993 | 8139620 |
| complete developmental cycle of leishmania mexicana in axenic culture. | a complete developmental sequence of leishmania mexicana has been produced in axenic culture for the first time. this was achieved by manipulation of media, ph and temperature conditions over a period of 16 days. all experiments were initiated with lesion amastigotes that were transformed to multiplicative promastigotes by culture in homem, 10% foetal calf serum, ph 7.5, at 25 degrees c. metacyclogenesis was induced by subpassage in schneider's drosophila medium, 20% foetal calf serum, ph 5.5, a ... | 1994 | 8152848 |
| evolution and expression of the leishmania surface proteinase (gp63) gene locus. | the leishmania surface proteinase, gp63, is the most abundant, surface-exposed protein on the promastigote form of the parasite. it is the product of a multigene family that, in some leishmania species, shows marked heterogeneity among its members. the differential expression of structurally distinct gp63 genes shows circumstantial correlation with the differential processing and localization of the protein in the intracellular, amastigote form of leishmania mexicana. the recent cloning and sequ ... | 1993 | 8162351 |
| characterization of polymer release from the flagellar pocket of leishmania mexicana promastigotes. | trypanosomatids contain a unique compartment, the flagellar pocket, formed by an invagination of the plasma membrane at the base of the flagellum, which is considered to be the sole cellular site for endocytosis and exocytosis of macromolecules. the culture supernatant of leishmania mexicana promastigotes, the insect stage of this protozoan parasite, contains two types of polymers: a filamentous acid phosphatase (sap) composed of a 100-kd phosphoglycoprotein with non-covalently associated proteo ... | 1994 | 8163549 |
| multiple high activity cysteine proteases of leishmania mexicana are encoded by the imcpb gene array. | the interrelationship of the multiple cysteine proteases (cps) found characteristically at high activity in leishmania mexicana amastigotes has been investigated. the mature forms of the five enzymes of groups b and c, which have subtly different substrate preferences, are the same size. enzymically deglycosylated group a cp proteins also have the same molecular mass. proteases of all three groups are specifically recognized by antisera raised against the group b or group c cps. in addition, cps ... | 1994 | 8180705 |
| an investigation into the significance of the n-linked oligosaccharides of leishmania gp63. | leishmania major promastigotes, when grown in the presence of tunicamycin (tm), produced a plasma membrane-bound, proteolytically active gp63 with a lower molecular weight than the native glycoprotein. however, this lower molecular weight form of gp63 continued to be recognized by concanavalin a (con a), suggesting that inhibition of n-linked glycosylation was not complete. metabolic labeling of gp63, using [35s]methionine, demonstrated that in the range of 5-10 micrograms ml-1 tm, only the lowe ... | 1994 | 8183321 |
| cutaneous leishmaniasis in tachira state, venezuela. | cutaneous and mucocutaneous leishmaniases are widely spread in the mountainous andean regions of south america. in venezuela, these regions consist of the coffee-growing states of trujillo, merida and tachira. entomological and parasitological investigations in three geographically different climatic zones (lomas bajas, delicias and la grita) in tachira state have shown a predominance of the sandfly species lutzomyia spinicrassa (verrucarum group) and two leishmania species, leishmania mexicana ... | 1994 | 8192512 |
| extracellular phosphorylation in leishmania major and leishmania mexicana during heat shock transformation. | the extracellular phosphorylation of exogenous substrates have been studied in two leishmania isolates, l. mexicana and l. major, that differ in their capacity to transform from promastigotes to amastigote-like cells when submitted to heat shock condition. when submitted to heat shock both parasites showed an increase in their extracellular phosphorylation activity. l. major promastigotes that do not transform to amastigote-like cells at 37 degrees c, do not phosphorylate exogenous substrate whe ... | 1994 | 8203291 |
| binding of c-reactive protein to leishmania. | | 1994 | 8206251 |
| 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 |
| the clinical and immunological spectrum of american cutaneous leishmaniasis. | american cutaneous leishmaniasis is characterized by a spectrum of clinical manifestations. these include localized, often self-healing single lesions, intermediate forms which frequently produce mucosal lesions and often show exaggerated delayed-type hypersensitivity (dth), and the rare diffuse cutaneous leishmaniasis in which no reaction of protective cell-mediated immunity or dth can be demonstrated. clinical, pathological and immunological studies have begun to unravel some of the mechanisms ... | 1993 | 8249076 |
| antigenic analysis of leishmania isolates from tachira state, venezuela. | studies of cutaneous leishmaniasis in 3 endemic foci in tachira state, western venezuela have revealed sympatric populations of parasites causing both cutaneous and mucocutaneous disease. immunological techniques and measurement of protease/acid phosphatase activities have been used to detect species-specific parasite antigens from 3 isolates from tachira. identified antigens of particular interest had molecular masses of 100, 82, 66, 50 and 27 kda, but there was a high degree of heterogeneity b ... | 1993 | 8249092 |
| 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 |
| effective immunization against cutaneous leishmaniasis with recombinant bacille calmette-guérin expressing the leishmania surface proteinase gp63. | leishmania parasites cause a spectrum of diseases that afflict the populations of 86 countries in the world. the parasites can survive within the lysosomal compartments of the host's macrophages, unless those macrophages are appropriately activated. despite the fact that protective immunity can be induced by vaccination with crude parasite preparations, little progress has been made toward a defined vaccine for humans. in this study the gene encoding the leishmania surface proteinase gp63 was cl ... | 1993 | 8265576 |
| lack of acidification in mycobacterium phagosomes produced by exclusion of the vesicular proton-atpase. | the success of mycobacterium species as pathogens depends on their ability to maintain an infection inside the phagocytic vacuole of the macrophage. although the bacteria are reported to modulate maturation of their intracellular vacuoles, the nature of such modifications is unknown. in this study, vacuoles formed around mycobacterium avium failed to acidify below ph 6.3 to 6.5. immunoelectron microscopy of infected macrophages and immunoblotting of isolated phagosomes showed that mycobacterium ... | 1994 | 8303277 |
| antimony quantification in leishmania by electrothermal atomic absorption spectroscopy. | tri- and pentavalent antimony were quantified in leishmania mexicana pifanoi amastigotes and promastigotes by atomic absorption spectroscopy with electrothermal atomization. leishmania grown in axenic culture were treated with either potassium antimony tartrate [sb(iii)] or sodium stibogluconate [sb(v)]. the parasites were collected, digested with nitric acid, and subjected to atomic absorption spectroscopy. the method was linear from 0 to 7 ng of antimony. the interassay coefficients of variati ... | 1993 | 8323020 |
| 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 |
| the lysosomal gp63-related protein in leishmania mexicana amastigotes is a soluble metalloproteinase with an acidic ph optimum. | leishmania mexicana amastigotes express a lysosomal protein, which is antigenically related to the promastigote surface metalloproteinase (gp63). it is shown that the purified gp63-related protein from amastigote is also an active metalloproteinase. the ph-optimum of the enzyme is acidic, similar to lysosomal cysteine proteinases, but distinct from the neutral to basic ph-optimum of the promastigote surface proteinase. this study appears to be the first report on a metalloproteinase with a lysos ... | 1993 | 8335086 |
| 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 |
| the glycoinositol phospholipids of leishmania mexicana promastigotes. evidence for the presence of three distinct pathways of glycolipid biosynthesis. | most macromolecules at the cell surface of parasitic protozoa of the genus leishmania, including the major surface glycoproteins and a complex lipophosphoglycan (lpg), are attached to the plasma membrane via glycosyl-phosphatidylinositol (gpi) anchors. free glycoinositol phospholipids (gipls) which are not linked to protein or phosphoglycan have also been found. in this study, we show that l. mexicana promastigotes synthesize two distinct gipl lineages, comprising at least 10 glycolipid species. ... | 1993 | 8340385 |
| [leishmaniasis: a preliminary epidemiological study in a locality of the endemic area in the state of the tabasco]. | the state of tabasco is localized in the endemic area of cutaneous leishmaniasis where both diffuse cutaneous leishmaniasis and mucocutaneous leishmaniasis have recently been reported. the objective of the present study was to obtain reliable information of the situation of this disease--which has a great relevance as a worldwide public health problem--through determination of the allergic index in a randomized sample from ranchería miguel hidalgo, comalcalco municipality, tabasco, mexico. we fo ... | 1993 | 8342080 |
| leishmania mexicana: proteinase activities and megasomes in axenically cultivated amastigote-like forms. | proteinase activities and megasomes were examined in axenically cultivated amastigote-like forms, freshly isolated lesion amastigotes, and promastigotes. megasomes were absent in promastigotes and present in both amastigote stages, but they seemed to be less numerous and more homogeneous in cultured amastigote-like forms. contrasting with the poor detection of proteinase activities in promastigote lysates, both types of amastigotes shared multiple proteinases, which were classified in two groups ... | 1993 | 8344407 |
| thermotherapy v. antimonials: what happens after the healing of cutaneous leishmaniasis lesions? | the long-term effects of meglumine antimoniate (chemotherapy) or exposure to an environmental temperature of 37 degrees c (thermotherapy) on the evolution of leishmania mexicana infections and on the response to challenge infections six months after treatment were compared in susceptible (balb/c) and partially resistant (c57bl/6) mice. thermotherapy was better than chemotherapy in that it healed lesions quicker and prevented relapses in the partially resistant mice during the observation period. ... | 1993 | 8346989 |
| the structure of leishmania major amastigote lipophosphoglycan. | intracellular amastigotes of leishmania major produce 6 x 10(4) copies/cell of a lipophosphoglycan (lpg) that is structurally distinct from the lpg produced by the extracellular promastigote form of l. major, leishmania donovani, and leishmania mexicana (reviewed by mcconville, m. j. (1991) cell biol. int. rep. 15, 779-798). l. major amastigote lpg is composed of a lysoalkyl phosphatidylinositol lipid anchor that links via a diphosphorylated hexasaccharide core to a phosphoglycan (6-100 kda). th ... | 1993 | 8360147 |
| karyotype polymorphism and conserved characters in the leishmania (viannia) braziliensis complex explored with chromosome-derived probes. | molecular karyotype of 45 reference populations of neotropical leishmanias was analyzed with ethidium bromide staining and with 6 chromosome-derived probes selected from a genomic library of leishmania (viannia) braziliensis. size-conserved patterns were identified and found to be specific to subgenus viannia and to its constitutive species. an important issue for epidemiology and clinical investigations was the discrimination between l. (v.) peruviana and l. (v.) braziliensis, 2 species found v ... | 1993 | 8368887 |
| 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 |
| polysaccharides isolated from plant cell cultures of echinacea purpurea enhance the resistance of immunosuppressed mice against systemic infections with candida albicans and listeria monocytogenes. | polysaccharides (ep) isolated from large scale plant cell cultures of echinacea purpurea, have been shown to activate human and murine phagocytes. in this study we investigated the influence of ep on the nonspecific immunity in immunodeficient mice. ep was effective in activating peritoneal macrophages isolated from animals after administration of cyclophosphamide (cp) or cyclosporin a (csa). ep-treated macrophages exhibited increased production of tumor necrosis factor-alpha (tnf) and enhanced ... | 1993 | 8375943 |
| ligand specificity of purified complement receptor type three (cd11b/cd18, alpha m beta 2, mac-1). indirect effects of an arg-gly-asp (rgd) sequence. | we have purified cr3 to homogeneity by affinity chromatography on c3bi-sepharose and elution with edta. c3bi-coated erythrocytes bound to this purified cr3, and binding was dependent on the concentration of both c3bi and cr3, as well as on temperature and the presence of divalent cations. moreover, binding could be blocked by mab against cr3 or c3bi and could be enhanced by the addition of integrin modulating factor-1. we used the purified cr3 to test whether several putative ligands of cr3 dire ... | 1993 | 8376780 |
| 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 |
| cutaneous leishmaniasis in british troops from belize. | the medical records of 306 british soldiers in whom a clinical diagnosis of cutaneous leishmaniasis had been made following a tour of duty in belize were analysed. parasitological confirmation of the diagnosis was established in 187 cases; leishmania were cultured in 117 cases and leishman-donovan bodies were identified histologically in a further 70 cases. leishmania braziliensis braziliensis was identified in 78 cases and leishmania mexicana mexicana in a further 29 cases. seventy-one per cent ... | 1993 | 8381299 |
| characterization of developmentally-regulated nucleases in promastigotes and amastigotes of leishmania mexicana. | the parasitic protozoon leishmania mexicana was examined for the presence of 3'-nucleotidase/nuclease using substrate sds-page. two activities were detected: one with an apparent molecular mass of 40 kda, and a doublet of 29/31 kda. the two enzymes showed differences in their levels of expression in the two life-cycle stages of parasite examined: the 29/31 kda doublet was detected at 60-fold higher levels in the pathogenic amastigote stage, but was also expressed by promastigotes, whereas the 40 ... | 1993 | 8385643 |
| 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 |
| inhibition of glycosylphosphatidylinositol biosynthesis in leishmania mexicana by mannosamine. | in several leishmania species, glycosylated inositol phospholipids exist as free lipids, as membrane protein anchors, and as the membrane-binding moieties of the lipophosphoglycans. both the glycolipid-anchored cell surface metalloproteinase, gp63, and the lipophosphoglycans have been proposed to be involved in cell invasion. moreover, the lipophosphoglycans have been implicated in the survival of leishmania in the parasitophorous vacuole of the host macrophage. in this report we show that manno ... | 1993 | 8387500 |
| a novel cdc2-related protein kinase from leishmania mexicana, lmmcrk1, is post-translationally regulated during the life cycle. | the p34cdc2 protein kinase is a key component in the regulation of the eukaryotic cell cycle. we have isolated from the protozoan parasite leishmania mexicana mexicana a cdc2-related kinase gene (lmmcrk1) encoding a 34-kda protein kinase (lmmcrk1) which has 56% amino acid identity with the human cdc2 and contains a pctair motif in place of the highly conserved pstair box. lmmcrk1 was detected in all life cycle stages at comparable levels, yet its histone h1 kinase activity was detected in only t ... | 1993 | 8407941 |
| leishmania mexicana promastigotes induce cytotoxic t lymphocytes in vivo that do not recognize infected macrophages. | the question is addressed whether antigens of leishmania, a parasite residing in the endosomal compartment of macrophages, can be presented in the context of major histocompatibility complex class i molecules. we used e. coli beta-galactosidase as a model antigen which can be expressed in high levels in l. mexicana promastigotes (l. mexicana-gal). infection of balb/c mice with l. mexicana-gal induces beta-galactosidase-specific cytotoxic t cells (ctl), which can be isolated using a beta-galactos ... | 1993 | 8419175 |
| 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 |
| identification of two distinct cysteine proteinase genes of leishmania pifanoi axenic amastigotes using the polymerase chain reaction. | a developmentally regulated cysteine proteinase associated with an unique lysosomal organelle, the megasome, has been described for the intracellular amastigotes of the leishmania mexicana complex; this proteinase appears to be important in the survival of the parasite. degenerate primers encoding the active sites residues have been used to amplify cysteine proteinase cdna sequences from axenically cultured amastigotes of leishmania pifanoi, a member of the l. mexicana complex. based on sequence ... | 1993 | 8426606 |
| structurally distinct genes for the surface protease of leishmania mexicana are developmentally regulated. | gp63 is a highly abundant glycosylphosphatidylinositol (gpi)-anchored membrane protein expressed in both the promastigote and the amastigote forms of leishmania species. in leishmania mexicana, gp63 exists as a heterogeneous family of proteins that are differentially processed and localized during the 2 developmental stages. in this study we determined the molecular organization of the l. mexicana gp63 gene family, demonstrating that the gp63 genes fall into 3 linked families of tandemly repeate ... | 1993 | 8426614 |
| diffuse cutaneous leishmaniasis in a cat. | an adult long-haired domestic cat native to south texas developed signs consistent with diffuse cutaneous leishmaniasis. cutaneous leishmaniasis, caused by leishmania mexicana, was initially diagnosed from lesions confined to the left ear. a radical pinnectomy was done and the cat was returned to its owner. two years later, lesions developed at the stump, and lesions later developed on the cat's muzzle and nasal mucosa. all of the lesions contained numerous l mexicana amastigotes. several treatm ... | 1993 | 8440634 |
| expression of lipophosphoglycan, high-molecular weight phosphoglycan and glycoprotein 63 in promastigotes and amastigotes of leishmania mexicana. | the abundant surface glycoconjugate of leishmania promastigotes, lipophosphoglycan (lpg), forms a blue-colored complex (lambda max = 649 nm) with the cationic dye stains-all, which can be quantitated densitometrically on polyacrylamide gels of cell lysates. promastigotes of leishmania mexicana, leishmania major and leishmania donovani yield values of 1-3 x 10(6) lpg molecules cell-1. in amastigotes the lpg content is down-regulated below the detection limit (< 10(3) molecules cell-1) in l. mexic ... | 1993 | 8459823 |
| uptake and metabolism of s-adenosyl-l-methionine by leishmania mexicana and leishmania braziliensis promastigotes. | promastigotes of leishmania mexicana and leishmania braziliensis incorporate s-adenosyl-l-[3h-methyl]methionine (adomet) against a concentration gradient through a saturable system. this concentrative uptake requires metabolic energy and is sensitive to temperature and sulfhydryl reagents such as n-ethyl maleimide. intracellular adomet exchanges with external adomet. at steady state, unaltered adomet in the intracellular pool is at about a 1800-fold concentration in relation to that found in the ... | 1993 | 8459824 |
| leishmania differentiation in natural and unnatural sand fly hosts. | leishmania differentiation in the gut of phlebotomine sand flies was evaluated based on five light and electron microscopic studies of natural (leishmania panamensis/lutzomyia gomezi, leishmania chagasi/lutzomyia longipalpis) and unnatural (leishmania mexicana/lutzomyia abonnenci, leishmania panamensis/phlebotomus papatasi, leishmania major/lutzomyia longipalpis) life cycles. in the bloodmeal, transformation of amastigotes into stumpy promastigotes occurred before or during division. further div ... | 1993 | 8461893 |
| 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 |
| effect of the anti-microtubule compound tubulozole on leishmania protozoan parasites in vitro. | for the cis and trans stereoisomers of the synthetic anti-microtubule compound tubulozole, at micromolar concentrations, tubulozole-c is cytotoxic to mammalian cells whereas tubulozole-t is not. the effect of tubulozoles on the parasitic protozoan leishmania was tested. for the promastigote stage of l. mexicana amazonensis, both isomers inhibited parasite growth. for the amastigote stage of l. mexicana amazonensis and l. major, within murine j774 macrophage line as host cells in vitro, tubulozol ... | 1993 | 8468004 |
| topical treatment of cutaneous leishmaniasis in belize: in vitro and in vivo studies with leishmania mexicana. | strains of leishmania mexicana isolated from belizian patients were found to be highly susceptible to paromomycin sulphate (pr) treatment. this drug at 100 micrograms ml-1 destroyed 85-99.5% of in vitro cultivated leishmania promastigotes within 4 days of exposure to the drug. leishmania promastigotes inoculated into the base of the tail of balb/c mice caused the development of local lesions several weeks after infection. these lesions were totally cleared of parasites after 20 days of topical t ... | 1993 | 8468127 |
| th1 and th2 t-cell subsets are differentially activated by macrophages and b cells in murine leishmaniasis. | the role of antigen-presenting cells in the differential expansion of th1 and th2 t cells in murine leishmaniasis was investigated. in general, macrophages preferentially induced gamma interferon and interleukin-2 secretion by syngeneic leishmania-specific t cells, whereas b cells were more efficient in activating interleukin 4 production. b cells from susceptible balb/c mice were better in inducing th2 responses than b cells from resistant c57bl/6 mice, whereas macrophages from c57bl/6 mice wer ... | 1993 | 8478122 |
| 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 |
| isolation of leishmania mexicana (kinetoplastida: trypanosomatidae) from lutzomyia anthophora (diptera: psychodidae) collected in texas. | three of 27 female lutzomyia anthophora (addis) collected in texas from the nest of a southern plains woodrat, neotoma micropus baird, during october 1991 were infected with flagellate protozoans. isolates were grown in schneider's drosophila medium supplemented with 20% fetal bovine serum, and isozyme analysis of two of the isolates determined the parasites to be leishmania mexicana (biagi). these are the first isolations of leishmania from field-collected sand flies in north america north of m ... | 1993 | 8510126 |
| leishmania mexicana: induction of metacyclogenesis by cultivation of promastigotes at acidic ph. | cultivation of recently transformed leishmania mexicana promastigotes at ph 5.5 in schneider's drosophila medium supplemented with 20% fetal calf serum produced a homogeneous stationary phase population morphologically similar to metacyclic forms. the cultured forms developed functional characteristics consistent with being metacyclic: they were resistant to complement-mediated lysis, possessed a discernable surface membrane coat in transmission electron micrographs, and were highly infective to ... | 1993 | 8513879 |
| 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 |
| stage-specific glycosphingolipids from amastigote forms of leishmania (l.) amazonensis. immunogenicity and role in parasite binding and invasion of macrophages. | neutral glycosphingolipids (gsls) from amastigote forms of leishmania (l.) amazonensis were isolated, and their structures and biological properties were characterized. based on various immunochemical methods, these gsls were shown to be expressed at certain stages of amastigote development. gsls were extracted and purified from amastigotes of hamster foot lesions by established procedures. three mouse monoclonal antibodies (moabs) specific for carbohydrate epitopes of these gsls were establishe ... | 1993 | 8514804 |
| 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 |
| molecular karyotype characterization of leishmania panamensis, leishmania mexicana, and leishmania major-like parasites: agents of cutaneous leishmaniasis in ecuador. | molecular karyotypes of leishmania isolates from patients with cutaneous leishmaniasis in ecuador were analyzed by pulsed-field gel electrophoresis (pfge) and southern blot hybridization. the dna karyotypes of l. major-like parasites were similar between two human isolates from a lowland coastal and a highland andean region, but were apparently different from those of eleven world health organization reference strains including l. major. the smallest chromosome of 240 kilobases in l. major-like ... | 1993 | 8517490 |