Matthew Rabinovitch

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125I-labeled rat preputial gland beta-glucuronidase was shown by light and electron microscopic radioautography to accumulate within the parasitophorous vacuoles of in vitro derived bone marrow macrophages infected with Leishmania mexicana amazonensis. beta-glucuronidase uptake was mediated by the mannose receptor, since the penetration of the ligand was(More)
L-leucine-methyl ester (Leu-OMe) kills Leishmania mexicana amazonensis amastigotes by a mechanism which requires proteolytic cleavage of the ester. N-Benzyloxycarbonyl-phenylalanyl-alanyl diazomethane (Z-Phe-AlaCHN2), a specific and irreversible inhibitor of cysteine proteinases, was used to characterize the enzymes involved in parasite destruction. It was(More)
Leishmania amastigotes, obligatory parasites of macrophages, lodge and multiply within long-lived phagolysosomelike "parasitophorous vacuoles" (PV). The glycoprotein horseradish peroxidase (HRP) was shown, by light and electron microscopic cytochemistry, to enter the PVs of rat in vitro-derived bone marrow macrophages infected with Leishmania mexicana(More)
Leishmania are flagellated protozoan parasites which, in their amastigote stages, survive and multiply within phagolysosome-like parasitophorous vacuoles (PV) of mammalian macrophages (MO). This study develops an earlier ultrastructural, incidental observation that zymosan particles (Z) were transferred to the PV of macrophages infected with Leishmania(More)
[Leishmania(L.)] amazonensis amastigotes reside in macrophages within spacious parasitophorous vacuoles (PVs) which may contain numerous parasites. After sporadic fusion events were detected by time-lapse cinemicrography, PV fusion was examined in two different models. In single infections, it was inferred from the reduction in PV numbers per cell. In a(More)
Leishmania amastigotes parasitize almost exclusively the mononuclear phagocytes of mammals. The organisms survive and multiply within acidified vacuoles (parasitophorous vacuoles; p.v.) akin to phagolysosomes. Certain amino acid esters are known to accumulate in and disrupt lysosomes. We postulated that, since Leishmania possess lysosome-like organelles,(More)
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(More)
Amino acid esters can destroy intracellular as well as isolated amastigotes of Leishmania mexicana amazonensis. In the present study we examined, using a tetrazolium reduction assay, the toxicity of the esters for amastigotes isolated from mouse lesions. Parasite killing by the "prototype" compound L-leucine methyl ester at 1 mM concentration and at pH 7.3(More)