Fetotoxicity caused by the interaction between zinc and arsenic in mice

Arsenic is an environmental pollutant that induces congenital malformations in experimental models and can contribute to human birth defects. The environmental exposure to arsenic is relatively small when compared with the doses required to cause teratogenicity in mice and other laboratory animals. In order to study the action of zinc in the arsenic-induced teratogenicity, in the present work mice were either pretreated with zinc and later with arsenic or were treated simultaneously with zinc and arsenic in vivo and in vitro. Following administration of arsenate on gestation day 8, pregnant females were killed on the 17th day of gestation; maternal and fetal data were collected by laparotomy and used to calculate reproductive parameters. Fetuses were analyzed for the presence of external malformation and, after the appropriate processing, visceral and skeletal analyses were accomplished. Conceptuses were exposed in whole embryo culture to arsenicals on gestation day 8 (3-6 somite stage). After a 26 h culture period, morphological development was assessed. Neither pretreatment with zinc nor simultaneous administration of zinc prevented arsenic teratogenicity in these experimental models. (C) 2002 Wiley-Liss, Inc.

Inflammatory reaction to the human bot-fly, Dermatobia hominis, in infested and reinfested mice

Two groups of mice were infested with first stage larvae of the human bot-fly, Dermatobia hominis (Linnaeus Jr) (Diptera: Oestridae). In the first group, skin biopsies were carried out 1, 3, 5, 7, 10 and 18 days after infestation. The second group was also infested but had all the larvae removed 5 days after infestation. The mice in the latter group were reinfested 4 weeks later and skin biopsies were carried out 1, 3, 5, 7, 10 and 18 days after reinfestation. In the first group, an inflammatory reaction began slowly, the neutrophils being the main inflammatory cells, eosinophils being scarce. The reaction progressed with time, developing a necrotic halo around the larvae containing inflammatory cells surrounded by fibroblasts. The inflammation invaded the adjacent tissue. In the second group, the inflammatory reaction was intense on the day immediately after reinfestation, the pattern being changed by the presence of a large number of eosinophils. Activated fibroblasts surrounding the necrotic area around the larvae appeared 3 days after reinfestation in the second group and 7 days after infestation in the first group. The results demonstrated that the previous contact with the antigens elicited the early arrival of eosinophils, probably through the chemotactic factors liberated by mast cells in the anaphylactic reaction.

Morphological investigations of the surface epithelium of ductuli efferentes of black isogenic mice (Mus musculus)

Morphological investigations of the epithelial cell types that line the ductuli efferentes (DE) of black isogenic mice confirm absorption of the luminal fluid phase by endocytosis as the main function of ductuli efferentes (DE) in this species. :Furthermore, all the histochemical and ultrastructural observations on the DE epithelial histoarchitecture indicate other cellular functions such as exocytosis and probably secretion: including an aprocrine secretory process.

Orchidopexy restores morphometric-stereologic changes in the caput epididymis and daily sperm production in cryptorchidic mice, although sperm transit time and fertility parameters remain impaired

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic basis of the resistance to Strongyloides venezuelensis (Nematoda, Rhabdiasidae) infection in mice (Mus musculus)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Strongyloides venezuelensis infection susceptibility of seven inbred strains of mice

Foi investigada a susceptibilidade de sete linhagens isogênicas de camundongos à infecção experimental, primária e secundária, por Strongyloides venezuelensis a fim de servir de base para estudos genéticos sobre a resistência. Foram utilizados 12 camundongos machos, com seis semanas de idade, das seguintes linhagens isogênicas: A/J, BALB/c, CBA/J, C3H/Hepos, C57BL/6, DBA/2 e NIH. Os animais foram inoculados, via sub-cutânea, com 2000 larvas infectantes. As contagens médias (± desvio padrão) de parasitas no intestino delgado dos camundongos seis dias após a infecção, em ordem crescente, foram: 28 (± 19) na linhagem NIH; 647 (± 228) na BALB/c; 709 (± 425) na DBA/2; 731 (± 151) na C3H/Hepos, 801 (± 174) na CBA/J; 1024 (± 267) na C57BL/6 e 1313 (± 483) na A/J. Os camundongos C57BL/6 apresentaram as mais elevadas contagens de ovos de S. venezuelensis por grama de fezes (OPG) e os NIH, as mais baixas. Não foram detectados ovos nos exames de fezes e não foram encontrados parasitas no intestino delgado dos animais re-infectados 14 dias após a infecção primária. A linhagem NIH apresentou elevada resistência contra as infecções primárias por S. venezuelensis. Entre as outras seis linhagens, uma das mais susceptíveis foi a linhagem C57BL/6.

Myotoxic effects of mastoparan from Polybia paulista (Hymenoptera, Epiponini) wasp venom in mice skeletal muscle

In a previous study, we showed that the Polybia paulista wasp venom causes strong myonecrosis. This study was undertaken to characterize the myotoxic potency of mastoparan (Polybia-MPII) isolated from venom (0.25 mu g/mu l) and injected in the tibial anterior (TA) muscle (i.m.) of Balb/c mice. The time course of the changes was followed at muscle degenerative (3 and 24 h) and regenerative (3, 7, and 21 days) periods (n = 6) after injection and compared to matched controls by calculation of the percentage of cross-sectional area affected and determination of creatine kinase (CK) activity (n = 10). The results showed that although NIP was strongly myotoxic, its capacity for regeneration was maintained high. Since the extent of tissue damage was not correlated with the CK serum levels, which remained very low, we raised the hypothesis that the enzyme underwent denaturation by the peptide. Evidence suggested that MP induced the death of TA fibers by necrosis and apoptosis and had the sarcolemma as its primordial target. Given its amphiphilic polycationic nature and based on the vast spectrum of functions attributed to the peptide, we suggest that MP interaction with cell membrane impaired the phosphorylation of dystrophin essential for sarcolemma mechanical stability, and disturbed Ca2+ mobilization with obvious implications on sarcoplasmic reticulum and mitochondrial functioning. (c) 2007 Elsevier Ltd. All rights reserved.

Genotoxic and mutagenic effects of fipronil on mice

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fipronil (active ingredient of acaricide frontline (R)) acting on the mice thyroid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Action of the chemical agent fipronil (active ingredient of acaricide Frontline (R)) on the liver of mice: An ultrastructural analysis

Fipronil, active ingredient of the acaricide Frontiline (R), is a phenyl-pyrazolic derivative, and its efficacy in the elimination of several plagues, even in low concentrations, has already been demonstrated; however, its effect on nontarget organisms has not been thoroughly explained. In this sense, the objective of this study was to evaluate the effects of different dosages of fipronil on the liver of mice in artificial conditions. Results showed that the animals exposed to fipronil present significant ultrastrucutural changes in hepatic cells with evident cellular and cytoplasm disorganization in hepatocytes characterized by an increase in the number of organelles, mainly mitochondria and rough endoplasmic reticulum, organelles that, in the case of the exposed animals, were probably responsible for the enzymes' synthesis that have the function of inactivating the toxic metabolites. A fat accumulation in the hepatocytes' cytoplasm (steatosis) was observed, in addition to extended vacuolated areas, mainly in regions next to the cell nucleus. Alterations observed in the nuclei of the hepatocytes pointed out cell death processes. Moreover, Kupffer cells increased in number (hyperplasia) suggesting an increase in the phagocytic activity of the liver in the exposed animals. Microsc. Res. Tech., 2011. (c) 2011 Wiley Periodicals, Inc.

Cytotoxicity of fipronil on mice liver cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of the polysaccharide beta-glucan on clastogenicity and teratogenicity caused by acute exposure to cyclophosphamide in mice

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of chemopreventive activity of glutamine by the comet and the micronucleus assay in mice's peripheral blood

This research has evaluated the effects of enteral supplementation of glutamine in clastogens and genotoxic damages caused by the acute administration of cisplatin. For this. it was utilized Swiss mice distributed in eight experimental groups: control, cisplatin, glutamine, in three different doses and the combination of these with cisplatin. The results show that the glutamine was present in neither genotoxic nor mutagenic activity. When in association with glutamine and cisplatin, in simultaneous treatment, it was verified the frequency decreased of micronuclei and comets. The damage reduction percentages to the micronucleus ranged from 95.4 to 91.8% after 24 h of administration of these compounds and 76.7 to 56.8% after 48 h. In the same time the damage reduction percentages to the comet test ranged from 117.0 to 115.0%. The results suggest that glutamine is capable of preventing genotoxic and mutagenic damage according to the experimental design proposed. (C) 2009 Elsevier B.V. All rights reserved.

The Allium cepa bioassay to evaluate landfarming soil, before and after the addition of rice hulls to accelerate organic pollutants biodegradation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Brine shrimp (Artemia salina Leach) bioassay of extracts from Lychnophoriopsis candelabrum and different Lychnophora species

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)