Leishmania Mexicana Research Articles

Implementación de un PCR-RFLP/Hsp70 para identificar y tipificar especies de Leishmania en una zona endémica a Leishmaniasis Cutánea Atípica en Honduras

Introducción. La leishmaniasis cutánea atípica es una variante no ulcerada de la leishmaniasis cutánea producida por Leishmania (L.) infantum. En Honduras está presente en los departamentos de La Paz, Francisco Morazán, Choluteca, El Paraíso y Valle. El espectro clínico incluye lesiones cutáneas menores a 10 mm y benignas hasta afecciones viscerales que pueden comprometer la vida del paciente. El objetivo del presente estudio fue implementar una técnica de biología molecular para la detección y tipificación de Leishmania spp en individuos con lesiones sospechosas a leishmaniasis cutánea atípica. Metodología. Para la implementación se usó ADN de cepas de referencia: Leishmania (L.) infantum chagasi, Leishmania (L.) mexicana, Leishmania (V.) panamensis, Leishmania (V.) braziliensis con un producto esperado de 1200 pares de base (pb). Se utilizaron las enzimas de restricción Hae III, BccI, RsaI y Mlul para la identificación de especies del género Leishmania. Se seleccionaron muestras clínicas (frotis en lámina) de los departamentos de Francisco Morazán y Valle. El estudio fue sometido al comité de ética de la Maestría en Enfermedades Infecciosas y Zoonóticas. Resultados: Se analizaron 39 muestras (27 de Francisco Morazán y 12 Valle). Se identificó a Leishmania (L.) infantum en el 100% de las muestras (29/29). Conclusiones/Recomendaciones: Se demostró que el polimorfismo del gen hsp70 junto con la digestión enzimática (RFLP) proporciona buenos resultados en la amplificación de parásitos a partir de muestras en lámina agilizando así el proceso de identificación molecular. Siendo una herramienta útil para tipificar especies de Leishmania spp en zonas donde prevalece más de una especie del parasito. Se recomienda realizar una vigilancia epidemiológica constante, para lograr determinar el comportamiento geográfico de las especies de Leishmania.

Cloning and characterization of Leishmania mexicana fructose-1,6-bisphosphate aldolase

Cloning and characterization of Leishmania mexicana fructose-1,6-bisphosphate aldolase

Leishmania mexicana: investigation offlagellar attachment by promastigotes in vitro

Leishmania mexicana: investigation offlagellar attachment by promastigotes in vitro

Effect of cimetidine and 2′-deoxyguanosine on the development of Leishmania mexicana in Balb/C mice

Journal Article Effect of cimetidine and 2′-deoxyguanosine on the development of Leishmania mexicana in Balb/C mice Get access Russell E. Coleman, Russell E. Coleman 1Department of Entomology University of Massachusetts, Amherst, MA 01003, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar John D. Edman, John D. Edman 1Department of Entomology University of Massachusetts, Amherst, MA 01003, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Lloyd H. Semprevivo Lloyd H. Semprevivo 2Department of Zoology, University of Massachusetts, Amherst, MA 01003, USA Search for other works by this author on: Oxford Academic PubMed Google Scholar Transactions of The Royal Society of Tropical Medicine and Hygiene, Volume 82, Issue 2, March-April 1988, Pages 232–233, https://doi.org/10.1016/0035-9203(88)90425-7 Published: 01 March 1988 Article history Received: 03 August 1987 Accepted: 16 September 1987 Published: 01 March 1988

Sodium stibogluconate (pentostam) inhibition of glucose catabolism via the glycolytic pathway, and fatty acid β-oxidation in leishmania mexicana amastigotes

The biochemical mechanism of action of antimony (Sb) in pentavalent form complexed to gluconic acid (sodium stibogluconate)—the drug of choice for the leishmaniases—has been only slightly investigated. We recently reported that, in stibogluconate-exposed Leishmania mexicana amastigotes, there is a dose-dependent decrease in the ATP/ADP ratio [Berman et al., Antimicrob. Agents Chemother. 27, 916 (1985)]. To investigate mechanisms by which ADP phosphorylation to ATP might be inhibited, stibogluconate-exposed amastigotes were incubated with [ 14C]glucose, fatty acid, or acetate, and 14CO 2 production was determined. In organisms exposed to 500 μg Sb/ml, formation of 14CO 2 from [6- 14C] glucose and [1- 14C]palmitate was inhibited 69 and 67% respectively. In comparison, formation of 14CO 2 from [1- 14C]glucose and [2- 14C]acetate was inhibited <15%. These results suggest that glucose catabolism via glycolytic enzymes and fatty acid β-oxidation, but not glucose metabolism via the hexosemonophosphate shunt or the citric acid cycle, is specifically inhibited in stibogluconate-exposed Leishmania mexicana amastigotes. Inhibition of these pathways suggests a mechanism for the inhibition of ADP phosphorylation previously reported.

Inhibition of growth and respiration of leishmania mexicana by the antitumor agent lonidamine

1. The antitumor drug lonidamine inhibited growth of promastigotes of Leishmania mexicana in axenic culture. 2. Fifty percent inhibition was attained at 0.42 mM, and was reflected mainly in an increase in lag time, with less effect on final cell yield. 3. The drug was leishmanistatic, since when a non-growing culture in the presence of 0.5 mM lonidamine was centrifuged and the cells resuspended in fresh medium, growth started and reached the control value. 4. Both coupled and FCCP-uncoupled respiration of intact promastigotes were inhibited by lonidamine; 50% inhibition was attained at 0.5 and 0.4 mM, respectively. 5. The results suggested that the mechanism of inhibition of growth of L. mexicana is, as proposed in the case of Trypanosoma cruzi epimastigotes and Trypanosoma brucei procyclic trypomastigotes, through inhibition of the energy metabolism.

Reversible defect in antigen-induced lymphokine and gamma-interferon generation in cutaneous leishmaniasis.

Peripheral blood mononuclear cells from a patient with progressive Leishmania mexicana (LM) infection were examined for responses to mitogen and antigen before, during, and after successful treatment. Before therapy, his cells proliferated normally and secreted effective macrophage-activating lymphokines in response to concanavalin A (Con A) and Toxoplasma gondii antigen, but failed to show any response to LM antigen. At this time, suppressive humoral factors were not present, the intracellular antimicrobial activity of the patient's monocytes was intact, and once stimulated with normal lymphokines, his monocyte-derived macrophages readily killed his own infecting LM strain. One month after initial treatment, the patient's T cells showed variable but measurable responses to LM antigen, and by 6 mo, these responses were fully developed in proliferative and lymphokine-generating assays. The patient's lymphokines were examined for gamma-interferon (IFN-gamma) because a) a monoclonal anti-human IFN-gamma antibody abolished the capacity of lymphokines to activate normal macrophages to kill LM, and b) partially purified and recombinant IFN-gamma alone could induce macrophage leishmanicidal activity. The patient's pretreatment Con A- and T. gondii antigen-stimulated lymphocyte supernatants (which activated macrophages to kill LM) contained 2000 to 3000 U/ml of IFN-gamma, whereas his LM antigen lymphokine was devoid of activity (less than 10 U/ml). At 1 and 6 mo after therapy, however, the latter lymphokine showed 20 and 600 U/ml of IFN-gamma, respectively, paralleling the development of antigen-specific proliferation and active lymphokine generation and the clinical status of his infection. These results appear to support previous suggestions that the ability of T cells to secrete antigen-induced macrophage-activating lymphokines (particularly IFN-gamma) is a key cellular immune response to intracellular Leishmania infections.

Destruction of leishmania mexicana amazonensis amastigotes within macrophages in culture by phenazine methosulfate and other electron carriers

Exposure of macrophages infected with Leishmania mexicana amazonensis to phenazine methosulfate (PMS) resulted in rapid damage and disappearance of the intracellular amastigotes without obvious ill effects to the host cells. The reduction of the percent infection was related to the concentration of PMS and to the duration of the pulse. Most Leishmania disappeared within 2 h of a 2-h pulse with 10 muM of the drug. In contrast, pretreatment of the macrophages with PMS followed by removal of the drug before infection did not result in disappearance of the parasites. The pH of the PMS medium markedly influenced the disappearance of Leishmania: maximum effect was observed at pH 8.0, while the effect was negligible at pH 6.3. The pH effect may be related to pseudobase formation by the PMS cation. Dose-response curves for PMS were similar for resident, elicited, or activated macrophages. Observations by time-lapse cinemicrography documented the explosion-like fragmentation of the amastigotes within 1-2 h of exposure of infected macrophages to the drug. Parasite-derived granules and vacuoles were seen to scatter within the parasitophorous vacuoles. This early damage to the parasites was confirmed by transmission electron microscopic observations. Infected macrophages incubated with PMS displayed detectable vacuolar fluorescence, indicating that PMS or a metabolite of PMS had access to the vacuoles. A series of other electron carriers, including phenyl methanes, phenazines, oxazines, a xanthene, and a naphthoquinone, given continuously for 18 h, also induced the disappearance of the Leishmania. The most potent was crystal violet, active at 70 nM. The presence of apolar substituents enhanced activity and this is probably related to increased permeation of the dyes. Finally, PMS, as well as other electron carriers examined, also reduced the growth of Leishmania promastigotes in culture. The results are compatible with a direct effect of the drugs on the intracellular amastigotes, involving only a permissive participation of the macrophages. We propose that the diverse agents destroy the amastigotes by redox-cycling generation of active oxygen metabolites at or near the parasites. Alternatively, the effect of the drugs could be mediated by toxic free radical reduction species of the drugs or by interference with electron flow or with the intermediary metabolism of Leishmania.

Immunity to leishmania mexicana following spontaneous recovery from oriental sore

1. 1) Two volunteers spontaneously recovered from infections with L. tropica were challenged with L. mexicana. The result was negative during an observation period of 3 years and 20 months, respectively. 2. 2) A volunteer not previously infected with leishmaniasis was inoculated with L. mexicana and became infected. This volunteer eventually gave typical delayed skin reactions after challenge with suspensions of L. tropica or L. mexicana.