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Paul A. Bates - One of the best experts on this subject based on the ideXlab platform.

  • Leishmania donovani and Cutaneous Leishmaniasis
    2020
    Co-Authors: Sri Lanka, H. V. Yamuna, D. Siriwardana, Harry Noyes, Nicholas J. Beeching, Michael L. Chance, Nadira D. Karunaweera, Paul A. Bates
    Abstract:

    To investigate the relationship of cutaneous Leishmaniasis isolates from Sri Lanka to known species, we performed DNA sequencing and microsatellite analyses. We identified Leishmania donovani as the agent of Sri Lanka cutaneous Leishmaniasis and showed that these parasites are closely related to those causing visceral Leishmaniasis in the Indian subcontinent.

  • Leishmania donovani and cutaneous Leishmaniasis sri lanka
    Emerging Infectious Diseases, 2007
    Co-Authors: H Yamuna V D Siriwardana, Harry Noyes, Nicholas J. Beeching, Michael L. Chance, Nadira D. Karunaweera, Paul A. Bates
    Abstract:

    To investigate the relationship of cutaneous Leishmaniasis isolates from Sri Lanka to known species, we performed DNA sequencing and microsatellite analyses. We identified Leishmania donovani as the agent of Sri Lanka cutaneous Leishmaniasis and showed that these parasites are closely related to those causing visceral Leishmaniasis in the Indian subcontinent.

  • The axenic cultivation of Leishmania donovani amastigotes
    Saudi Medical Journal, 1999
    Co-Authors: Haytham A. Zakai, Michael L. Chance, Paul A. Bates
    Abstract:

    Leishmania parasite cause a wide range of human disease from localized self-healing cutaneous lesions to fatal visceral disease. These parasites are characterized by having a non-motile form, Amastigotes, within the macrophage of the mammalian host and a motile form, promastigote, in the sand fly. Transformation of Promastigotes has been attracting considerable attention in studying the parasite-host interaction. It is the purpose of this article to review the transformation of Promastigotes to Amastigotes and the growth of the later form in cell free medium, i.e. axenically. Also, results of original work on axenic Amastigotes of Leishmania donovani are shown. The effect of temperature, pH and gas requirements on the transformation and further growth of Leishmania donovani axenic amastigotes are discussed.

Charles L. Jaffe - One of the best experts on this subject based on the ideXlab platform.

  • heterocycle fused lupane triterpenoids inhibit Leishmania donovani amastigotes
    MedChemComm, 2014
    Co-Authors: Raisa Haavikko, Charles L. Jaffe, Abedelmajeed Nasereddin, Nina Sacerdotisierra, Dmitry Kopelyanskiy, Sami Alakurtti, Mari Tikka, Jari Ylikauhaluoma
    Abstract:

    The synthesis of heterocyclic betulin derivatives and their activity against Leishmania donovani is reported. Betulonic acid was used as a versatile intermediate. Several different fused heterocycles were introduced at the 2,3-position of the lupane skeleton including isoxazole, pyrazine, pyridine, indole and pyrazole rings. Also the 28-position was modified. Three compounds, 5, 8 and 25, showed low micromolar activity with IC50 values of 13.2, 4.3 and 7.2 μM, respectively. Compound 8 showed the best activity and selectivity, and its activity was tested on infected macrophages using a concentration, 5 μM, where no macrophage toxicity was exhibited. Interestingly, the activity of compound 8 on axenic amastigotes and Leishmania-infected macrophages was similar.

  • Effect of pH and temperature on protein kinase release by Leishmania donovani
    International Journal for Parasitology, 2002
    Co-Authors: Lita L Vieira, Nina Sacerdoti-sierra, Charles L. Jaffe
    Abstract:

    Abstract During their life cycle Leishmania are exposed to environments that differ markedly in pH and temperature. The effect of these factors on protein kinase release into the surrounding environment by Leishmania donovani promastigotes was examined. Promastigotes release protein kinase activity both constitutively and following induction by incubation with an exogenous substrate, phosvitin. The substrate specificity of the constitutive and induced activities was similar, unlike that previously described for Leishmania major promastigotes. The Leishmania donovani enzymes phosphorylate phosvitin, but not casein, mixed histones or protamine sulphate, and both activities are shed over a wide pH range from 6 to 9. Transfer of promastigotes from pH 7.4/30°C to pH 5.0–5.5/37°C, conditions that mimic those encountered by parasites following transmission from sandflies to a mammalian host and uptake by macrophages, inhibited release of the constitutive activity. Identical conditions had only a minor effect on induced protein kinase release. Both types of protein kinase activities released at pH 7.4 were still active when assayed at pH 5.0. Characterisation of the constitutive and induced promastigote protein kinases showed that casein kinase 1- and casein kinase 2-like activities are released by Leishmania donovani . Constitutive enzyme release decreased over time, however, the addition of phosvitin to these ‘casein kinase-depleted’ promastigotes induced elevated casein kinase 1 and casein kinase 2 shedding. These results suggest that shed protein kinase might play a role in parasite survival and adaptation to host environments.

Sukhbir Kaur - One of the best experts on this subject based on the ideXlab platform.

  • Chronic heat-shock treatment driven differentiation induces apoptosis in Leishmania donovani.
    Molecular and cellular biochemistry, 2006
    Co-Authors: Puneet Raina, Sukhbir Kaur
    Abstract:

    The present study investigates the role of apoptosis in the regulation of cell numbers of Leishmania donovani during the in vitro differentiation of promastigote stage to amastigote stage in axenic conditions. We report that apoptosis is induced in Leishmania donovani due to chronic heat-shock treatment of 37 ( degrees )C that also mediates the differentiation of promastigotes to amastigotes. This is characterized by the fragmentation of DNA, blebbing in the parasite cell membrane, nuclear condensation, formation of preapoptotic bodies and involvement of Ca(++) in the apoptotic process. The flowcytometric analysis shows an early and steep rise in percentage apoptotic nuclei till 48-hour stage of differentiation and then a gradual decline, suggesting synergistic action of Ca(++) ATPase and probably Hsp70. Hsp70 might be rescuing cells from apoptosis in the death signaling pathway. Incubation of the culture with Ca(++) chelator EGTA (1 mM) brings down the percentage of apoptotic nuclei considerably showing thereby that calcium is needed for the process of cell death here that occurs by apoptosis. The survival of the infective individuals appears to be decided by the parasite in the early stages of its differentiation. Our studies show the potential of the physiological temperature of 37 ( degrees )C in inducing apoptosis in Leishmania donovani and the therapeutic use it can be put to.

  • Chronic heat-shock treatment driven differentiation induces apoptosis in Leishmania donovani
    Molecular and Cellular Biochemistry, 2006
    Co-Authors: Puneet Raina, Sukhbir Kaur
    Abstract:

    The present study investigates the role of apoptosis in the regulation of cell numbers of Leishmania donovani during the in vitro differentiation of promastigote stage to amastigote stage in axenic conditions. We report that apoptosis is induced in Leishmania donovani due to chronic heat-shock treatment of 37 °C that also mediates the differentiation of promastigotes to amastigotes. This is characterized by the fragmentation of DNA, blebbing in the parasite cell membrane, nuclear condensation, formation of preapoptotic bodies and involvement of Ca++ in the apoptotic process. The flowcytometric analysis shows an early and steep rise in percentage apoptotic nuclei till 48-hour stage of differentiation and then a gradual decline, suggesting synergistic action of Ca++ ATPase and probably Hsp70. Hsp70 might be rescuing cells from apoptosis in the death signaling pathway. Incubation of the culture with Ca++ chelator EGTA (1 mM) brings down the percentage of apoptotic nuclei considerably showing thereby that calcium is needed for the process of cell death here that occurs by apoptosis. The survival of the infective individuals appears to be decided by the parasite in the early stages of its differentiation. Our studies show the potential of the physiological temperature of 37 °C in inducing apoptosis in Leishmania donovani and the therapeutic use it can be put to.

Rashmi Bankoti - One of the best experts on this subject based on the ideXlab platform.

Åsa Holm - One of the best experts on this subject based on the ideXlab platform.