Immunometabolic Circuits in Infection for Advancing Host Directed Therapies.

Immuno-metabolism is a pivotal determinant in the progression of leishmaniasis. Synthetic biology-based approach has garnered significant attention as a step toward therapeutic intervention targeting host-associated factors that drive leishmaniasis. Synthetic biology entails the engineering of genetic components in an orthogonal and modular manner to precisely modulate biological systems, imparting novel functions to cells. In the presented study, elucidation of a systematic pipeline for the development of an inducible tetracycline-controlled (TetON)-based synthetic circuit was aimed at delivering succinate dehydrogenase as a therapeutic agent to facilitate the elimination of intracellular Leishmania parasites. The outlined protocol describes the designing of a synthetic circuit and its subsequent validation. The proposed strategy also concentrates on the incorporation of synthetic circuits in the plasmid backbone as a delivery vehicle. Additionally, delivery machinery employing polyplexes-based nano-particles for the delivery of synthetic circuits was used in murine macrophage cell lines without compromising the cellular morphology. Standardization of the method was conducted for selecting transfected cells and determining optimal induction concentration for synthetic circuit expression. Observations reveal a distinct reduction in intracellular parasite burden in transfected cells compared to infected cells. Pro-inflammatory cytokines were expressed post-infection in synthetic circuit transfected and induced cells as a mechanism to promote parasite elimination. This underscores the synthetic biology-based method as a potent approach in leishmaniasis by targeting host factors associated with disease progression.

Treatment options for leishmaniasis.

Leishmaniasis is broadly classified into three types: cutaneous, mucocutaneous and visceral. The visceral form is most dangerous and can result in death. Although leishmaniasis is an ancient disease, its treatment is still challenging. Several drugs, differing in their cost, toxicity, treatment duration and emergence of drug resistance, are used for different types of leishmaniasis. To overcome these limitations, the search for newer drugs and other treatments continues. In this article, we discuss conventional drugs, other treatments, including newer options such as immunotherapy and immunochemotherapy, and future prospects for leishmaniasis treatment.

Immunotherapy in treatment of leishmaniasis.

Leishmaniasis caused by various species of protozoan transmitted by sand fly vectors occurs as a spectrum of clinical features including cutaneous, mucocutaneous and visceral forms. It is a geographically distributed parasitic disease and a major public health problem in the world. The clinical syndromes are highly variable depending on the parasite species, host genetics, vectors and environment. To date, there is no effective vaccine and traditional treatments are toxic, expensive with long administration duration and many adverse side effects and/or drug resistance. Instead of treatments based on chemotherapy, certain strategies aim to recover leishmaniasis and reduce the parasitic burden. Immunotherapy has focused on the induction of effective immune response to rapidly control the disease. Recent studies have indicated that a single dose of a suitable therapeutic vaccine induces a quick and lasting recovery in patients. Immunotherapy reduces the toxicity of drug and the emergence of resistance dramatically. It could be an effective addition to chemotherapy with a safe and potent drug compared with monotherapy, resulting in a prophylactic and therapeutic cure of leishmaniasis. This review has focused on treatment of leishmaniasis with particular emphasis on immunotherapy as an alternative to conventional drug treatment.

Potential therapeutic targets shared between leishmaniasis and cancer.

The association of leishmaniasis and malignancies in human and animal models has been highlighted in recent years. The misdiagnosis of coexistence of leishmaniasis and cancer and the use of common drugs in the treatment of such diseases prompt us to further survey the molecular biology of Leishmania parasites and cancer cells. The information regarding common expressed proteins, as possible therapeutic targets, in Leishmania parasites and cancer cells is scarce. Therefore, the current study reviews proteins, and investigates the regulation and functions of several key proteins in Leishmania parasites and cancer cells. The up- and down-regulations of such proteins were mostly related to survival, development, pathogenicity, metabolic pathways and vital signalling in Leishmania parasites and cancer cells. The presence of common expressed proteins in Leishmania parasites and cancer cells reveals valuable information regarding the possible shared mechanisms of pathogenicity and opportunities for therapeutic targeting in leishmaniasis and cancers in the future.

Immunotherapeutic Potential of Interleukin-32 and Trained Immunity for Leishmaniasis Treatment.

Neglected tropical diseases annually account for several million infections worldwide. Efficacious treatment for these poorly understood infectious diseases is often limited to ineffective, expensive, and toxic therapies such as the SbV used for leishmaniasis patients. Here, we review the latest discoveries and literature on the molecular pathways, cell types, and immune mediators involved in the immune response to infection with New World Leishmania spp. in humans and their interaction with the adaptive and innate immune system. Novel developments in the field of trained innate immunity and the recently described role of IL-32 are emphasized as potential immunotherapeutic treatments for the management of leishmaniasis.

DNA flowerstructure co-localizes with human pathogens in infected macrophages.

Herein, we characterize the cellular uptake of a DNA structure generated by rolling circle DNA amplification. The structure, termed nanoflower, was fluorescently labeled by incorporation of ATTO488-dUTP allowing the intracellular localization to be followed. The nanoflower had a hydrodynamic diameter of approximately 300 nanometer and was non-toxic for all mammalian cell lines tested. It was internalized specifically by mammalian macrophages by phagocytosis within a few hours resulting in specific compartmentalization in phagolysosomes. Maximum uptake was observed after eight hours and the nanoflower remained stable in the phagolysosomes with a half-life of 12 h. Interestingly, the nanoflower co-localized with both Mycobacterium tuberculosis and Leishmania infantum within infected macrophages although these pathogens escape lysosomal degradation by affecting the phagocytotic pathway in very different manners. These results suggest an intriguing and overlooked potential application of DNA structures in targeted treatment of infectious diseases such as tuberculosis and leishmaniasis that are caused by pathogens that escape the human immune system by modifying macrophage biology.

Camel nanobodies: Promising molecular tools against leishmaniasis.

AIM: To characterize several anti-Leishmania tropica nanobodies and to investigate their effect on Leishmania infection. METHODS: Several immunological tests were implied to characterize five different (as confirmed by sequencing) anti-L tropica nanobodies (NbLt05, NbLt06, NbLt14, NbLt24 and NbLt36) against parasite lysates or intact cells from different stages, promastigotes and amastigotes. Direct inhibitory effect of these nanobodies on parasite infection cycle on macrophages was tested in cell culture. RESULTS: All the five nanobodies (with distinguished characteristics) were more specific to L tropica than to L major, but could equally recognize the lysate and the outer surface of the intact cells from the two main stages of the parasite. Nanobodies recognized several leishmania antigens (majorly between 75 and 63 kDa), and their proteinaceous nature was confirmed. Because of its role in leishmania life cycle, gp63 was considered a potential antigen candidate for nanobodies, and bioinformatics predicted such interaction. All nanobodies have a negative effect on the infectivity of L tropica, as they decreased the number of infected macrophages and the amastigotes inside those macrophages. CONCLUSION: Such anti-leishmania nanobodies, with outstanding characteristics and important target, can be of great use in the development of promising treatment strategies against leishmaniasis.

Identificación de especies de Leishmania en pacientes derivados al Instituto Nacional de Salud del Perú / Identification of Leishmania species in patients derived to the National Institute of Health, Peru

RESUMEN En el Perú, la leishmaniasis es una enfermedad metaxénica que representa un serio problema de salud pública, debido a su amplia distribución y al número de personas en riesgo de contraer la enfermedad, siendo la población vulnerable principalmente las personas de bajos recursos económicos. El estudio se realizó a partir de pacientes que fueron derivados al Instituto Nacional de Salud entre el 2006 y el 2011 para que se les realizara el diagnóstico especializado. La identificación de la especie de Leishmania infectante se desarrolló mediante el análisis de las curvas de disociación (HRMA) obtenidas a partir del ADN genómico de promastigotes y amastigotes, lo que permitió identificar las especies de Leishmania (Viannia) braziliensis, Leishmania (V.) guyanensis, Leishmania (V.) peruviana como las más prevalentes, además de Leishmania (V.) lainsoni y Leishmania (L.) amazonensis.

ABSTRACT In Peru, leishmaniasis is a metaxenic disease that represents a serious public health problem, due to its wide distribution and the number of people in danger of contracting the disease, being the vulnerable population mainly those with low economic resources. The study was conducted from patients who were derived to Peru's National Institute of Health between 2006 and 2011 so that the specialized diagnosis could be carried out. The identification of the species of infectious Leishmania was developed through the analysis of the High-Resolution Melting Analysis obtained from the genomic DNA of promastigotes and amastigotes, which allows to identify the species of Leishmania (Viannia) braziliensis, Leishmania (V.) guyanensis, Leishmania (V.) peruviana as more prevalent, in addition to Leishmania (V.) lainsoni and Leishmania (L.) amazonensis.

Prospects for antimicrobial peptide-based immunotherapy approaches in Leishmania control.

INTRODUCTION: Leishmaniasis is one of the neglected tropical diseases and is highly endemic in many countries. Currently, there is no adequate human vaccine and treatment to control the disease. Areas covered: As a result of the failure of chemotherapy and toxicity, it is necessary to find another approach for the treatment of leishmaniasis. Recently, antimicrobial peptides (AMPs), originating from natural resources, have attracted much attention for their use as a new antibiotics for many infectious and noninfectious diseases. Natural AMPs are named interchangeably as host defense peptides. They are naturally active in the innate immune system as a primary defense mechanism in most species all over the world. Several AMPs have been tested in in vitro and in vivo experiments against leishmaniasis. Expert commentary: Most AMPs require proper conformation to be active. Leishmania (L.) tarentolae as a nonpathogenic strain, is an effective tool not only for vaccine development but also for therapy. Recombinant L. tarentolae expressing selective or combined AMPs is a suggestive approach for leishmaniasis or any other infectious disease treatment.

Renal dialysis and long-term treatment of a dog with kidney disease associated with canine leishmaniosis.

BACKGROUND: Renal disease is considered the main cause of natural mortality in dogs with canine leishmaniosis. The pathological mechanisms associated with kidney injury in canine leishmaniosis include immune complex glomerulonephritis, tubulointerstitial nephritis and occasionally renal amyloidosis. Proteinuria is a frequent finding in canine leishmaniosis and its quantification by the urine protein-creatinine ratio (UPC) is an important parameter in the staging of canine lesihmaniosis as presented by the LeishVet group. RESULTS: A 4.5 year-old spayed female Belgian Malinois dog was presented to the Hebrew University Veterinary Teaching hospital with epistaxis and rhinitis and diagnosed also with proteinuria and acute kidney injury (AKI IRIS grade V) associated with canine leishmaniosis that developed to LeishVet stage III with chronic kidney disease (CKD) after stabilization. Clinicopathologic abnormalities included azotemia with a peak creatinine concentration of 7.76 mg/dl (reference interval, 0.3-1.2 ng/dl), hypoalbuminemia (1.76 g/dl, reference interval 3-4.4 g/dl), hyperglobulinemia (4.54 g/dl, reference interval 1.8-3.9 g/dl) and proteinuria (urine protein/creatinine ratio 15.6, normal < 0.2). Serology by the enzyme-linked immunosorbent assay (ELISA) for Leishmania infantum was positive with high antibody levels. The dog was hospitalized and treated with intermittent hemodialysis, feeding through an esophageal feeding tube, medical treatment for protein losing nephropathy and antileishmanial treatment with allopurinol. Kidney function gradually improved and the dog's creatinine levels and proteinuria decreased until complete normalization two years after the acute insult. However, rhinitis and sneezing persisted and although the anti-leishmanial antibodies decreased over time, the dog remains constantly seropositive. CONCLUSIONS: To our knowledge, this is the first report of hemodialysis management of AKI associated with canine leishmaniosis. Hemodialysis was imperative in stabilizing the dog's renal disease and controlling its azotemia. It demostrates that hemodialysis can be beneficial in the management of acute deterioration of kidney disease in canine leishmaniosis.

Leishmaniasis and various immunotherapeutic approaches.

Leishmaniasis is a vector-borne infectious disease caused by multiple Leishmania (L.) species with diverse clinical manifestations. There is currently no vaccine against any form of the disease approved in humans, and chemotherapy is the sole approach for treatment. Unfortunately, treatment options are limited to a small number of drugs, partly due to high cost and significant adverse effects. The other obstacle in leishmaniasis treatment is the potential for drug resistance, which has been observed in multiple endemic countries. Immunotherapy maybe another important avenue for controlling leishmaniasis and could help patients control the disease. There are different approaches for immunotherapy in different infectious diseases, generally with low-cost, limited side-effects and no possibility to developing resistance. In this paper, different immunotherapy approaches as alternatives to routine drug treatment will be reviewed against leishmaniasis.

Neolignanas semissintéticas como novos candidatos anti-leishmania: estudo do mecanismo ação / Semissintéticas as new candidates oncometopia facialis anti-leishmania: study of action mechanism

Doenças tropicais negligenciadas, como a leishmaniose visceral (LV), afetam populações de baixa renda e apresentam um desafio para a saúde pública. A quimioterapia disponível para LV apresenta diversas limitações, como elevada toxicidade e custo, além de dificuldades de administração. Na busca por alternativas terapêuticas, o estudo de produtos naturais representa uma forma promissora na introdução de novos medicamentos para essa doença. No presente trabalho, foi realizada uma triagem in vitro em Leishmania (L.) infantum de 25 novos compostos semissintéticos derivados da neolignana desidrodieugenol B, isolada da planta Nectandra leucantha (Lauraceae). Dentre eles, quatro (FS017, FS034, FS008 e FS022) demonstraram atividade em amastigotas intracelulares e promastigotas, com...

Development of a rapid loop-mediated isothermal amplification assay for diagnosis and assessment of cure of Leishmania infection.

BACKGROUND: Leishmaniasis is a spectrum of diseases with great relevance to public health. Conventional diagnostic methods are time consuming, needing trained personnel. A robust, rapid and cost effective diagnostic test is warranted for on-time diagnosis and field application. METHODS: We have developed a loop mediated isothermal amplification (LAMP) assay with primers (n = 6) based on Leishmania donovani kDNA for detection of Leishmania infection, using a closed tube to prevent cross-contamination. The assay was used to detect Leishmania infection in biological samples obtained from patients of visceral leishmaniasis (VL), post kala-azar dermal leishmaniasis (PKDL) and cutaneous leishmaniasis (CL). RESULTS: The assay was positive for L. donovani, L. tropica and L. major parasites, with the highest sensitivity towards L. donovani (1 fg DNA). The high sensitivity of the assay for detection of L. donovani was reflected in its ability to detect parasite DNA within 30 min of amplification time with a threshold detection limit of ≥25 copies per reaction. The assay detected parasite in 64 of 66 VL blood samples (sensitivity, 96.9%; 95% CI: 89.6-99.2%), 15 of 15 VL bone marrow aspirate samples (sensitivity, 100%; 95% CI:79.6-100%), 65 of 67 PKDL tissue biopsy samples (sensitivity, 97%; 95% CI:89.7-99.2%). The assay was evaluated in a few cases of CL wherein it was found positive in 8 of 10 tissue biopsies (sensitivity, 80%; 95% CI: 49-94.3%). The assay was negative in all control blood (n = 76) and tissue biopsy (n = 24) samples (specificity, 100%; 95% CI: 96.3-100%). Further, the assay was evaluated for its utility in assessment of cure in treated VL and PKDL patients. The assay detected parasite DNA in 2 of 20VL blood samples and 2 of 21 PKDL tissue samples. Out of 4 cases that were positive for parasite DNA at post treatment stage, 2 patients (1VL and 1 PKDL) returned with relapse. CONCLUSIONS: The study demonstrated a Leishmania genus specific closed tube LAMP assay for reliable and rapid molecular diagnosis of VL and PKDL with potential for application in assessment of cure.

Cardiac manifestations of parasitic diseases.

The heart may be affected directly or indirectly by a variety of protozoa and helminths. This involvement may manifest in different ways, but the syndromes resulting from impairment of the myocardium and pericardium are the most frequent. The myocardium may be invaded by parasites that trigger local inflammatory response with subsequent myocarditis or cardiomyopathy, as occurs in Chagas disease, African trypanosomiasis, toxoplasmosis, trichinellosis and infection with free-living amoebae. In amoebiasis and echinococcosis, the pericardium is the structure most frequently involved with consequent pericardial effusion, acute pericarditis, cardiac tamponade or constrictive pericarditis. Chronic hypereosinophilia due to helminth infections, especially filarial infections, has been associated with the development of tropical endomyocardial fibrosis, a severe form of restrictive cardiomyopathy. Schistosomiasis-associated lung vasculature involvement may cause pulmonary hypertension (PH) and cor pulmonale Tropical pulmonary eosinophilia, which is characterised by progressive interstitial fibrosis and restrictive lung disease, may lead to PH and its consequences may occur in the course of filarial infections. Intracardiac rupture of an Echinococcus cyst can cause membrane or secondary cysts embolisation to the lungs or organs supplied by the systemic circulation. Although unusual causes of cardiac disease outside the endemic areas, heart involvement by parasites should be considered in the differential diagnosis especially of myocardial and/or pericardial diseases of unknown aetiology in both immunocompetent and immunocompromised individuals. In this review, we updated and summarised the current knowledge on the major heart diseases caused by protozoan and metazoan parasites, which either involve the heart directly or otherwise influence the heart adversely.

Avaliação da atividade anti-Leishmania e anti-Trypanosoma do extrato etanólico das folhas de Annona squamosa L / Evaluation of the anti-leishmania and anti-trypanosoma activity of ethanolic extract from the leaves of Annona squamosa L

As doenças parasitárias, também chamadas de “doenças negligenciadas”, continuam sendo uma grande dificuldade para o desenvolvimento social e econômico dos países mais pobres. Podemos citar como exemplo dessas doenças, a leishmaniose e a doença de Chagas. A leishmaniose é causada por parasitas do gênero Leishmania e afeta cerca de 12 milhões de pessoas. A doença de Chagas, causada pelo protozoário Trypanosoma cruzi, causa aproximadamente 50.000 mortes por ano. Os fármacos disponíveis para o tratamento dessas doenças são altamente tóxicos, sendo este um dos motivos que leva à busca por drogas eficazes e seguras para seus tratamentos. As folhas da Annona squamosa, espécie da família Annonaceae, já foram descritas na literatura por suas atividades hepatoprotetora, antiparasitária, pesticida e antimicrobiana. Nesse estudo avaliamos a atividade anti-leishmania e tripanocida do extrato etanólico das folhas de Annona squamosa L. (EEAS) em formas promastigota do parasita Leishmania braziliensis e Leishmania infantum e epimastigota de Trypanosoma cruzi, além de avaliar a atividade citotóxica em fibroblasto. Os resultados demonstram que o extrato apresentou uma melhor atividade contra Leishmania infantum e Leishmania brasiliensis quando comparados com Trypanosoma cruzi; e que apresentou uma maior toxicidade nas concentrações de 500 e 1000 μg/ml, com mortalidade dos fibroblastos de aproximadamente 85% e 100%, respectivamente. Esse estudo aponta para uma perspectiva terapêutica alternativa que se mostrou eficaz frente aos parasitas aqui estudados, exceto a forma epimastigota de Trypanosoma cruzi. Com relação aos testes de citotoxicidade fazem-se necessários novos testes, uma vez que apresentou um alto nível de toxicidade, viabilizando assim futuros ensaios in vivo.

The parasitic diseases, also calls by “neglected diseases”, continue being a major difficulty for the social and economic development of the poorest countries. We can cite as an example of these diseases, the leishmaniasis and the Chagas disease. Leishmaniasis is caused by parasites of the genus Leishmania and affects about 12 million people. The Chagas disease, caused by the protozoan Trypanosoma cruzi, causes approximately 50,000 deaths per year. The drugs available for the treatment of these diseases are highly toxic, being this one of the reasons that leads to the search for effective and safe drugs for their treatments. The leaves of the Annona squamosa, species of the family Annonaceae, have already been described in the literature by their hepatoprotective activities, antiparasitic, pesticide and antimicrobial. In this study we assessed the activity tripanocidal and antileishmania of ethanolic extract from the leaves of Annona squamosa L. (EEAS) in promastigota forms of the parasite Leishmania braziliensis and Leishmania infantum and epimastigota of Trypanosoma cruzi, in addition to evaluating the cytotoxic activity in fibroblasts. The results demonstrate that the extract presented a better activity against Leishmania infantum and Leishmania brasiliensis when compared with Trypanosoma cruzi; and which presented a greater toxicity at concentrations of 500 and 1000 μg/ml, with mortality of fibroblasts of approximately 85% and 100%, respectively. This study points to an alternative therapeutic perspective that showed effective against the parasites here studied, except the epimastigota form of Trypanosoma cruzi. With relation to cytotoxicity tests are required new tests, once presented a high level of toxicity, thus enabling future in vivo assays.

Theranostic applications of phage display to control leishmaniasis: selection of biomarkers for serodiagnostics, vaccination, and immunotherapy.

Phage display is a high-throughput subtractive proteomic technology used for the generation and screening of large peptide and antibody libraries. It is based on the selection of phage-fused surface-exposed peptides that recognize specific ligands and demonstrate desired functionality for diagnostic and therapeutic purposes. Phage display has provided unmatched tools for controlling viral, bacterial, fungal, and parasitic infections, and allowed identification of new therapeutic targets to treat cancer, metabolic diseases, and other chronic conditions. This review presents recent advancements in serodiagnostics and prevention of leishmaniasis -an important tropical parasitic disease- achieved using phage display for the identification of novel antigens with improved sensitivity and specificity. Our focus is on theranostics of visceral leishmaniasis with the aim to develop biomarker candidates exhibiting both diagnostic and therapeutic potential to fight this important, yet neglected, tropical disease.

Theranostic applications of phage display to control leishmaniasis: selection of biomarkers for serodiagnostics, vaccination, and immunotherapy

Phage display is a high-throughput subtractive proteomic technology used for the generation and screening of large peptide and antibody libraries. It is based on the selection of phage-fused surface-exposed peptides that recognize specific ligands and demonstrate desired functionality for diagnostic and therapeutic purposes. Phage display has provided unmatched tools for controlling viral, bacterial, fungal, and parasitic infections, and allowed identification of new therapeutic targets to treat cancer, metabolic diseases, and other chronic conditions. This review presents recent advancements in serodiagnostics and prevention of leishmaniasis -an important tropical parasitic disease- achieved using phage display for the identification of novel antigens with improved sensitivity and specificity. Our focus is on theranostics of visceral leishmaniasis with the aim to develop biomarker candidates exhibiting both diagnostic and therapeutic potential to fight this important, yet neglected, tropical disease.

Avaliação não-clínica da segurança do antimoniato de meglumina em roedores: toxicocinética, toxicidade para o desenvolvimento e efeitos sobre citocromos P450 hepáticos / Non-clinical safety of meglumine antimoniate evaluation in rodents: toxicokinetics, developmental toxicity and effects on liver cytochromes P450

Antimoniais pentavalentes são considerados medicamentos de primeira linha no tratamento das diferentes formas de leishmaniose. O perfil de segurança dos medicamentos à base de antimônio (Sb), entretanto, ainda não foi completamente elucidado. O objetivo deste conjunto de estudos que constam desta tese foi fornecer informações adicionais sobre a segurança de um curso de tratamento com o antimoniato de meglumina (AM). O primeiro estudo investigou o acúmulo e eliminação do Sb do sangue e órgãos de ratos machos adultos tratados com uma dose diária de AM, por um período de 21 dias consecutivos. Foi observado que o antimônio é lentamente eliminado. O segundo estudo avaliou o desenvolvimento pós-natal da prole nascida e amamentada por ratas tratadas na gestação e lactação até o desmame com AM. A transferência de Sb através da placenta e via leite materno para a prole foi determinada. Os resultados mostraram, em geral, que o desenvolvimento pós-natal e a fertilidade dos ratos expostos não foram alterados. Os dados também sugerem que o Sb passa facilmente para o leite e está presente nesta matriz biológica em uma forma química que o torna bem absorvido pelos lactentes. Além disso, nós também investigamos se as atividades das enzimas citocromo P450 hepáticas (CYP), que participam do metabolismo de endo- e xenobióticos, foram alteradas pelo tratamento. Os resultados mostraram que um curso de tratamento de 24 dias com AM causou um consistente declínio das atividades de CYP1A no fígado de camundongos SW e DBA-2, e uma diminuição nas atividades de CYP2B9/10 nas fêmeas de SW, mas não em DBA-2 de ambos os sexos...

Pentavalent antimony compounds are considered as first choice drugs to treat different clinical manifestations of leishmaniasis. The safety profile of antimony-based anti-leishmanial drugs, however, has not been entirely elucidated so far. The objective of the set of experimental studies presented in this thesis was to provide additional information on the safety of a course of treatment with meglumine antimoniate (MA). The first study was an investigation of the accumulation and clearance of antimony (Sb) in the blood and organs of adult male rats treated with a 21-day course of MA. It was observed that residual Sb is slowly eliminated from rat’s organs and blood. The second study evaluated the postnatal development of the offspring born to and nursed by rats treated during gestation and lactation until weaning with MA. The transfer of Sb via placenta and mothers’ milk to the offspring was determined as well. Results showed that offspring postnatal development and fertility remained virtually unaltered after treatment with MA. Data suggested that Sb is transferred into breast milk and is present there in a chemical form that makes this metalloid bioavailable to suckling pups. Furthermore, we investigated whether activities of liver cytochrome P450 enzymes that take part in the metabolism of endogenous and exogenous substances were altered after a course of treatment with MA. It was found that a 24-d course of treatment with MA caused a consistent decline in CYP1A activity in the mouse liver. A decrease of CYP2B9/10 activity was noted in SW females but not in SW males and in DBA-2 of either sex...