Weverton M Sampaio

Federal University of Minas Gerais, Belo Horizonte, Estado de Minas Gerais, Brazil

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Publications (4)9.92 Total impact

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    ABSTRACT: The toxicity and antileishmanial effectiveness of a novel liposome formulation of meglumine antimoniate in mongrel dogs with visceral leishmaniasis (VL) obtained from a region where VL is endemic in Brazil have been investigated. Groups of 12 animals received by the intravenous route four doses (with 4-day intervals) of either liposomal meglumine antimoniate (group I [GI], 6.5 mg Sb/kg of body weight/dose), empty liposomes (GII), or isotonic saline (GIII). Evaluation of markers of hematopoietic, hepatic, and renal functions before and just after treatment showed no significant change. On the other hand, transitory adverse reactions, including prostration, defecation, tachypnea, and sialorrhea, were observed during the first 15 min after injections in GI and GII. Parasitological evaluation of sternal bone marrow 4 days after the last dose showed a significant reduction of parasite burden in GI, compared to the other groups. Immunocytochemical evaluations of the skin, bone marrow, cervical lymph nodes, livers, and spleens of dogs for parasites, 150 days after treatment, indicated significant parasite suppression (higher than 95.7%) in the lymph nodes, livers, and spleens of GI, compared to control groups. Feeding of Lutzomyia longipalpis phlebotomines on dogs from GI, 150 days after treatment, resulted in a significant reduction of sand fly infection efficiency, compared to feeding on animals from GII and GIII. This is the first report of both long-term parasite suppression and reduction of infectivity to sand flies in naturally infected dogs following treatment with a liposome-encapsulated drug. Importantly, this was achieved using a 20-fold-lower cumulative dose of Sb than is used for conventional antimonial treatment.
    Antimicrobial Agents and Chemotherapy 08/2008; 52(7):2564-72. · 4.57 Impact Factor
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    ABSTRACT: The evaluation of the efficacy of an immunochemotherapy protocol to treat symptomatic dogs naturally infected with Leishmania chagasi was studied. This clinical trial had the purpose to test the combination of N-methyl meglumine antimoniate (Glucantime and the second generation recombinant vaccine Leish-110f plus the adjuvant MPL-SE to treat the canine leishmaniasis (CanL). Thirty symptomatic naturally infected mongrel dogs were divided into five groups. Animals received standard treatment with Glucantime or treatment with Glucantime Leish-110f + MPL-SEas immunochemotherapy protocol. Additional groups received Leish-110f + MPL-SE only, MPL-SE only, or placebo. Evaluation of haematological, biochemical (renal and hepatic function) and plasmatic proteins, immunological (humoral and cellular immune response) and the parasitological test revealed improvement of the clinical parameters and parasitological cure in dogs in both chemotherapy alone and immunochemotherapy cohorts. However, the immunotherapy and immunochemotherapy cohorts had reduced number of deaths, higher survival probability, and specific cellular reactivity to leishmanial antigens, in comparison with chemotherapy cohort only and control groups (adjuvant alone and placebo). These results support the notion of using well-characterized recombinant vaccine as an adjunct to improve the current chemotherapy of CanL.
    Vaccine 04/2008; 26(12):1585-94. · 3.49 Impact Factor
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    ABSTRACT: There are a few works considering the characterization of canine monocyte-derived macrophages as well as a standardized procedure for isolation, culture, and infection of these cells with Leishmania. We have performed several modifications in order to improve the canine monocyte-derived macrophage cultures. In addition, we have done a comparative study between monocytes and monocyte-derived macrophages from dogs naturally and experimentally infected with L. chagasi. In the presence of exogenous serum, opsonized Leishmania promastigotes binds better to monocytes/macrophages than without serum. Otherwise, this binding occurs due to the strict correlation between the opsonized biologic particles with the third receptor of the complement (CR3-CD11b/CD18). In fact, our assays with CD11b confirmed the importance of this receptor for canine cells and the L. chagasi experimental system. Moreover, monocytes obtained from naturally infected dogs have shown a higher number of monocytes bounded to promastigotes. The experimental results regarding survival have shown that promastigote forms of opsonized L. chagasi were more infective, because we found higher numbers of promastigotes bound to the different cells. As a consequence, after forty-eight hours of binding, higher numbers of amastigotes appeared inside monocyte-macrophages. These studies have given support to continue comparative studies involving canine monocytes, monocyte-derived macrophages and peritoneal macrophages. Since we have standardized the canine cell culture, we are looking forward to determining the phenotypic properties of these cells before and after L. chagasi infection using flow cytometry.
    BMC Veterinary Research 02/2007; 3:11. · 1.86 Impact Factor
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    ABSTRACT: et al.; Histopathological and parasitological analysis of skin tissues biopsies from two distinct anatomical areas of the ears of dogs naturally infected with Leishmania (Leishmania) chagasi. Braz J Vet Pathol; 2008, 1(1): Abstract Canine visceral leishmaniasis is an endemic disease in Latin America caused by Leishmania (Leishmania) chagasi and transmitted to man and animals by infected blood-sucking sandflies) of the genus Lutzomyia. Dogs are considered to be the primary domestic reservoir of disease because they present an intense cutaneous parasitism. The aim of this study was to evaluate the intensity of the inflammatory process and to compare it to the parasite load of tissue from two different sites of the ear skin of dogs naturally infected with Leishmania chagasi. We think that exist a specific anatomical region that exhibits a relatively higher rate of parasitism. For diagnostic analysis, serological tests were carried out using the indirect fluorescence antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA). Twelve animals naturally infected with Leishmania chagasi were euthanatized with a lethal dose of Sodium Thiopental™ and T61™. During the necropsy, fragments of the extremity and middle anatomical regions of the ear were collected. All tissues were fixed in a 10% formalin solution and then paraffin-embedded for histopathological (HE) and immunohistochemical analysis. The streptoavidin-peroxidase immunohistochemistry method was used to detect tissue amastigotes using optical microscopy. Our results indicated a chronic inflammatory reaction, ranging from discrete to an intense magnitude. The inflammatory process was more frequently observed in the extremity of the ear than in the middle portion of the ear (p<0.05). The presence of parasites in the ear extremity was higher than in other evaluated regions. A positive correlation between the tissue inflammation, parasitism, and serological data was confirmed at both ear positions (p<0.05). Skin biopsies are an important tool for CVL diagnosis and the ear extremity represents an appropriated area to perform the assays.