Seroprevalence of anti-Leptospira spp. antibodies in dogs in Bahia, Brazil.

The aim of this study was to determine the prevalence of anti-Leptospira spp. antibodies in dogs living in the urban area of the city of Ilhéus, Bahia, Brazil using the microscopic agglutination test (MAT) to investigate 24 serovars. A semi-structured questionnaire was administered to dog owners to collect data about demography, husbandry and environmental factors. The prevalence of anti-Leptospira spp. antibodies in the population of 282 dogs was 7.1% (95% confidence interval: 4.4-10.7%). Serovar Copenhageni was the most prevalent, followed by serovars Bratislava, Canicola and Gryppotyphosa. No risk factor was detected with regard to demography (age, gender and breed), husbandry (Leptospira vaccinations, food and water exposure through their environment, hunting habits, contact with other animals and contact with rats) and environmental factors (sewage network, garbage collection, history of flooding, river proximity and wastelands). Despite the low prevalence found in this study, the seroprevalence of Leptospira spp. in healthy dogs in Ilhéus indicates the presence of this agent in the environment, which may be a source of human infection. Knowledge of the serovars present in this environment is important for understanding the epidemiology of leptospirosis and establishing public health policies aimed at its control.

Absence of chemopreventive influence of propolis on the rat liver altered foci development.

Propolis (bee glue) is a complex mixture of natural substances that exhibits a broad spectrum of biological activities. As the possibility exists that it may exert a chemopreventive role against cancer development, the present study aimed to evaluate the chemopreventive influence of a Brazilian aqueous propolis extract (APE) in a rat two-stage (initiation-promotion) medium-term bioassay for chemical liver carcinogenesis. Male Wistar rats were sequentially initiated with diethylnitrosamine (DEN, 200mg/kgb.w.) and, 2 weeks later, exposed to a diet containing hexachlorobenzene (HCB, 100ppm) and to APE 0.1% through drinking water for 6 weeks. Appropriate control groups were also established. The animals were sacrificed at the weeks 8th and 30th when liver samples were processed to evaluate the development of altered hepatocyte foci (AHF) identified under hematoxylin and eosin (H&E) staining and by the immunohistochemical expression of the enzyme glutathione S-transferase placental form (GST-P). The results indicate that APE 0.1% did not protect against the development of any of the differentially identified putative preneoplastic foci in DEN-initiated animals, exposed or not to the promoting agent HCB. Also, APE 0.1% by itself did not significantly induce any AHF, what is in line with its already known absence of genotoxic potential. Our results indicate that an aqueous extract of Brazilian propolis did not exert chemoprevention on the hepatocarcinogenesis process chemically induced in the rat.

Liver lesions produced by aflatoxins in Rana catesbeiana (bullfrog).

This study describes alterations induced in Rana catesbeiana (bullfrog) liver after extended dietary exposure to aflatoxins (AFs). Bullfrogs of both sexes were fed for 120 days a commercial chow blended with a rice bran-based mixture of AFs containing 667.0, 11.65, 141.74, and 3.53 mg/kg of AFs B1, B2, G1, and G2, respectively. Animals were sacrificed on study days 45, 90, and 120. Severe and progressive liver lesions with structural collapse, increased hepatocyte and biliary duct cell proliferation, appearance of basophilic hepatocytes, and diffuse scarring, were observed at all time points. There were no quantitative alterations in the liver melanomacrophage centers of the AFs-exposed animals. Increased amounts of lipid hydroperoxides, indicative of ongoing oxidative stress, were more evident in the Addutor magnum muscle than in the AFs-damaged livers. No tumors were found in the R. catesbeiana livers after 120 days of exposure to relatively high doses of AFs.

Efeito do extrato aquoso da própolis sobre a hepatocarcinogênese química em modelo de média duração em ratos Wistar machos / Effect of aqueous extract of propolis on chemical hepatocarcinogenesis in the model of average duration in male Wistar rats

A própolis é um complexo de substâncias naturais cujas atividades terapêuticas têm sido relatadas por diversos autores. Dentre estas atividades, seu potencial quimiopreventivo é controverso. O objetivo deste trabalho foi avaliar o efeito do extrato aquoso da própolis de origem brasileira (EAP, 0,13% na água de beber) sobre a hepatocarcinogênese química em um protocolo de média-duração de duas etapas, com iniciação pela dietilnitrosamina (DEN, 200 mg/kg de peso corporal, ip, dose única) e promoção com baixa concentração de hexaclorobenzeno (HCB, 100 ppm) na ração. Os animais foram sacrificados após oito e 30 semanas de experimentação. Os fígados foram coletados e processados histologicamente para análise da incidência de focos de hepatócitos alterados (FHA), sob coloração de hematoxilina e eosina, e para a análise quantitativa do número e área de FHA que expressavam a enzima glutationa S-transferase (GST-P mais), identificados por reação imunoistoquímica. Os resultados indicam que a administração do EAP não influenciou o desenvolvimento destas lesões pré­-neoplásicas. O tratamento com EAP, isoladamente, não induziu o aparecimento de focos GST-P mais além dos níveis basais (FHA espontâneos), observados no grupo controle (NaCI). Estes resultados sugerem que, nas condições do presente experimento, o EAP 0,13% não exerceu efeito quimiopreventivo sobre a hepatocarcinogênese em ratos.