Arylimidamides (AIAs) represent a new class of molecules that exhibit potent antileishmanial activity (50% inhibitory concentration [IC 50 ], <1 M) against both Leishmania donovani axenic amastigotes and intracellular Leishmania, the causative agent for human visceral leishmaniasis (VL). A systematic lead discovery program was employed to characterize in vitro and in vivo antileishmanial activities, pharmacokinetics, mutagenicities, and toxicities of two novel AIAs, DB745 and DB766. They were exceptionally active (IC 50 < 0.12 M) against intracellular L. donovani, Leishmania amazonensis, and Leishmania major and did not exhibit mutagenicity in an Ames screen. DB745 and DB766, given orally, produced a dose-dependent inhibition of liver parasitemia in two efficacy models, L. donovani-infected mice and hamsters. Most notably, DB766 (100 mg/kg of body weight/day for 5 days) reduced liver parasitemia in mice and hamsters by 71% and 89%, respectively. Marked reduction of parasitemia in the spleen (79%) and bone marrow (92%) of hamsters was also observed. Furthermore, these compounds distributed to target tissues (liver and spleen) and had a moderate oral bioavailability (up to 25%), a large volume of distribution, and an elimination half-life ranging from 1 to 2 days in mice. In a repeat-dose toxicity study of mice, there was no indication of liver or kidney toxicity for DB766 from serum chemistries, although mild hepatic cell eosinophilia, hypertrophy, and fatty changes were noted. These results demonstrated that arylimidamides are a promising class of molecules that possess good antileishmanial activity and desirable pharmacokinetics and should be considered for further preclinical development as an oral treatment for VL.Leishmaniasis, a neglected tropical disease, is caused by parasitic protozoa of the genus Leishmania, including 20 species that are pathogenic for humans (21). Clinical manifestations of leishmaniasis mainly consist of cutaneous, mucocutaneous, visceral, and post-kala-azar dermal leishmaniasis, with symptoms ranging from skin and mucosal ulceration to systemic infection that is fatal if left untreated (6). An estimated 12 million people are currently infected with Leishmania, and up to 350 million people in 88 countries are at risk of infection (35). Approximately 2 million new cases of leishmaniasis are believed to occur annually, with 1.5 million for cutaneous leishmaniasis and 0.5 million for visceral leishmaniasis (VL). In macrophages, Leishmania amastigotes adapt to thrive in an acidic subcellular compartment, the parasitophorous vacuole (PV; pH ϳ5) (2), where they maintain a neutral intracellular pH within the parasite by an energy-dependent process (9). Multiple layers of membrane barriers (i.e., host macrophage plasma membrane, phagolysosomal membrane, and Leishmania amastigote plasma membrane) presumably present a formidable challenge for chemotherapeutic agents to target Leishmania parasites in mammalian hosts.Current chemotherapies for leishmaniasis have many limitations, including resis...

We examined the immunopathology and the expression of human immunodeficiency virus type 1 (HIV-1) in lumbosacral dorsal root ganglia (DRGs) from 16 patients with acquired immunodeficiency syndrome (AIDS) and 10 HIV-1-seronegative controls. Using in situ hybridization, we detected HIV-1 RNA in a few perivascular cells in DRGs from five of 16 AIDS patients (31%). In addition, using polymerase chain reaction, we detected HIV-1 DNA more frequently in DRGs from four of five AIDS patients (80%) examined. We detected interleukin-6 (IL-6) immunoreactivity in endothelial cells in DRGs from seven of 16 AIDS patients (44%) but from none of 10 HIV-1-seronegative controls (0%). We found more nodules of Nageotte, CD8+ T lymphocytes, and intercellular adhesion molecule-1 (ICAM-1)-positive endothelial cells and mononuclear cells in DRGs from AIDS patients than in DRGs from controls. Increased numbers of nodules of Nageotte in DRGs of AIDS patients were associated with detection of HIV-1 RNA by in situ hybridization and detection of IL-6 by immunohistochemistry. We conclude that low levels of replication of HIV-1, through cytotoxic T lymphocytes or expression of cytokines, may play a role in the subclinical degeneration of sensory neurons frequently observed in DRGs of AIDS patients.

Isoniazid (INH) is a first-line antibiotic used in the treatment of infections caused by Mycobacterium tuberculosis. However it has a serious limitation of being hepatotoxic. Delineating the mechanism underlying INH-induced hepatotoxicity may be beneficial in devising ways to counteract its toxic manifestations. Studies in human hepatoma HepG2 cells have indicated that INH exposure causes induction of apoptosis. This study was aimed at identifying the key components/pathways of the INH-induced apoptotic pathway using HepG2 cells. HepG2 cells were exposed to increasing concentrations of INH (6.5, 13, 26, and 52 mM). Hydrogen peroxide (0.3 mM) served as positive control. After incubating for specific time intervals cells were harvested and evidences of cytotoxicity, oxidative stress, and apoptosis were sought. The findings indicated that INH exposure causes increased ROS generation along with alteration in levels of enzymatic antioxidants such as Superoxide dismutase, Catalase, and Glucose-6-Phosphate dehydrogenase. Altered Bcl-2/Bax content, cytochrome-c translocation, caspase activation, and DNA fragmentation emphasized involvement of apoptosis.

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Visceral leishmaniasis, a vector-borne disease caused by Leishmania donovani and Leishmania infantum , currently affects 12 million individuals in 88 countries. In the present study, a real-time PCR (rt-PCR) assay has been optimized and validated against 2 other routine methods, i.e., microscopy and limiting dilution culture assay, to estimate parasite load in the liver of infected Syrian hamsters (Mesocricetus auratus). A set of specific primers amplified a 116-bp target template of the kinetoplastid DNA of L. donovani in a SYBR® Green-based rt-PCR assay. To assess the methods, we tested 2 anti-leishmanial compounds belonging to the class of arylimidamides, DB745 (2,5-bis[2-ethoxy-4-(2-pyridylimino)aminophenyl]furan) and DB766 (2,5-bis[2-(2-propoxy)-4-(2-pyridylimino)aminophenyl]furan) for efficacy in vivo in Syrian hamsters infected with L. donovani promastigotes. Parasite load was quantified in liver by all 3 methods and was found comparable. Of the 3 methods, rt-PCR was the fastest and most convenient, sensitive, and reproducible method.