Eduardo Fernandes Bondan

Prevalência de Cryptosporidium sp. em cães de instituições da cidade de São Paulo

OBJETIVO: Os caes sao importante fonte de infeccao da criptosporidiose para o homem. O objetivo do estudo foi avaliar a ocorrencia de Cryptosporidium sp. em caes e, adicionalmente, comparar duas tecnicas de analise fecal. METODOS: Foram analisadas 450 amostras fecais de caes na cidade de Sao Paulo entre 2003 e 2004. Os especimes fecais foram randomicamente selecionados: 200 amostras de caes provenientes de um hospital veterinario universitario publico (grupo 1) e 250 amostras de canis particulares (grupo 2). A pesquisa de Cryptosporidium sp. foi realizada empregando-se a coloracao de Ziehl-Neelsen modificada e a tecnica de PCR. Foi empregado o teste de duas proporcoes com intervalo de confianca de 0,05 (z critico=±1,645). RESULTADOS: Foram encontrados somente oocistos de Cryptosporidium parvum. A prevalencia observada pela microscopia de luz foi de 8,8% e com a tecnica de PCR foi de 9,5%. Os animais jovens apresentaram menor frequencia (5,5%) em relacao aos adultos (10,1%) e nao se observou diferenca estatisticamente significante na prevalencia entre machos e femeas. CONCLUSOES: A prevalencia de C. parvum na populacao canina estudada foi semelhante as observadas em outros estudos e acometendo em igual proporcao machos e femeas. A tecnica de PCR permitiu a deteccao de um numero maior de casos positivos que a microscopia de luz.

Expectativa de vida e causas de morte em cães na área metropolitana de São Paulo (Brasil)

In order to evaluate the canine life expectation in the metropolitan area of Sao Paulo, as well as the causes of death of these animals, data related to 2,011 dogs attended at a University Veterinary Hospital or collected from veterinary clinics, kennels and private owners were analyzed. It was observed that the median age of the dogs at death due to all causes was 36 months old. Dogs of medium, large and giant breeds had longer longevity than the small ones. Female and neutered dogs lived longer than male and intact dogs. There was no difference in life expectation related to the fact that the animal was from a pure breed or not. The most important causes of mortality were, in decrescent order of occurrence, infeccious diseases, neoplasms and traumatic injuries. Canine life expectation found in this survey was shorter than that observed in other countries and infeccious diseases constitute the major cause of death.

Behaviour of oligodendrocytes and Schwann cells in an experimental model of toxic demyelination of the central nervous system

Oligodendrocytes and Schwann cells are engaged in myelin production, maintenance and repairing respectively in the central nervous system (CNS) and the peripheral nervous system (PNS). Whereas oligodendrocytes act only within the CNS, Schwann cells are able to invade the CNS in order to make new myelin sheaths around demyelinated axons. Both cells have some limitations in their activities, i.e. oligodendrocytes are post-mitotic cells and Schwann cells only get into the CNS in the absence of astrocytes. Ethidium bromide (EB) is a gliotoxic chemical that when injected locally within the CNS, induce demyelination. In the EB model of demyelination, glial cells are destroyed early after intoxication and Schwann cells are free to approach the naked central axons. In normal Wistar rats, regeneration of lost myelin sheaths can be achieved as early as thirteen days after intoxication; in Wistar rats immunosuppressed with cyclophosphamide the process is delayed and in rats administered cyclosporine it may be accelerated. Aiming the enlightening of those complex processes, all events concerning the myelinating cells in an experimental model are herein presented and discussed.Oligodendrocitos e celulas de Schwann realizam a producao e manutencao das bainhas de mielina, respectivamente no sistema nervoso central (SNC) e periferico (SNP). As celulas de Schwann, a diferenca dos oligodendrocitos, sao capazes de invadir o SNC para remielinizar axonios desmielinizados, sempre que os astrocitos tenham sido destruidos. O brometo de etidio e uma droga gliotoxica usada para induzir desmielinizacao com o desaparecimento precoce de astrocitos, de modo que as celulas de Schwann tem liberdade para invadir o SNC. Em ratos Wistar normais, a remielinizacao e detectada treze dias apos desmielinizacao; em ratos Wistar imunossuprimidos com ciclofosfamida a reparacao do tecido e tardia, enquanto que em animais tratados com ciclosporina ela e acelerada. O objetivo do artigo e discutir todas as etapas do processo de destruicao e reparacao da mielina em um modelo experimental de desmielinizacao em ratos.

Delayed Schwann cell and oligodendrocyte remyelination after ethidium bromide injection in the brainstem of Wistar rats submitted to streptozotocin diabetogenic treatment

Schwann cell disturbance followed by segmental demyelination in the peripheral nervous system occurs in diabetic patients. Since Schwann cell and oligodendrocyte remyelination in the central nervous system is a well-known event in the ethidium bromide (EB) demyelinating model, the aim of this investigation was to determine the behavior of both cell types after local EB injection into the brainstem of streptozotocin diabetic rats. Adult male Wistar rats received a single intravenous injection of streptozotocin (50 mg/kg) and were submitted 10 days later to a single injection of 10 microL 0.1% (w/v) EB or 0.9% saline solution into the cisterna pontis. Ten microliters of 0.1% EB was also injected into non-diabetic rats. The animals were anesthetized and perfused through the heart 7 to 31 days after EB or saline injection and brainstem sections were collected and processed for light and transmission electron microscopy. The final balance of myelin repair in diabetic and non-diabetic rats at 31 days was compared using a semi-quantitative method. Diabetic rats presented delayed macrophage activity and lesser remyelination compared to non-diabetic rats. Although oligodendrocytes were the major remyelinating cells in the brainstem, Schwann cells invaded EB-induced lesions, first appearing at 11 days in non-diabetic rats and by 15 days in diabetic rats. Results indicate that short-term streptozotocin-induced diabetes hindered both oligodendrocyte and Schwann cell remyelination (mean remyelination scores of 2.57 +/- 0.77 for oligodendrocytes and 0.67 +/- 0.5 for Schwann cells) compared to non-diabetic rats (3.27 +/- 0.85 and 1.38 +/- 0.81, respectively).

Ruptura da barreira hematoencefálica após injeção de droga gliotóxica no tronco encefálico de ratos wistar

Ethidium bromide (EB) causes local astrocytic disappearance, with glia limitans disruption and supposed blood-brain barrier (BBB) breakdown The aim of this study was to investigate the BBB integrity after the injection of 0.1% EB (group E) or 0.9% saline solution (group C) into cisterna pontis of Wistar rats. Brainstem fragments were collected from 24 hours to 31 days post-injection for ultrastructural study and GFAP immuno-histochemical staining. Some animals received colloidal carbon ink by intravenous route at the same periods. In rats from group C, there was no sign of astrocyte loss and no leakage of ink from blood vessels in the injection site. In group E, astrocyte disappearance began at 48 hours and some areas were still devoid of astrocytic processes 31 days after. Leakage of carbon particles was seen from 48 hours to 7 days in the EB-induced lesions. Tight junctions did not show any detectable ultrastructural change due to the lack of perivascular astrocytes.

Single early prenatal lipopolysaccharide exposure impairs striatal monoamines and maternal care in female rats

AIMS Environmental information received by a mother can induce a phenotype change in her offspring, commonly known as a maternal effect (trans-generational effect). The present work verified the effects of lipopolysaccharide (LPS), which mimics bacterial infection, on maternal care and on the activity of related brain areas in F1 offspring, i.e., female rats that were prenatally exposed to LPS. MAIN METHODS Pregnant rats received 100μg/kg of LPS intraperitoneally on gestational day (GD) 9.5. Female offspring of the F1 generation were mated to naïve males and were evaluated during their lactation period for open field, maternal and aggressive behaviors. Striatal and hypothalamic dopamine and serotonin levels and turnover were also evaluated. Furthermore, astrocyte protein expression in the nucleus accumbens (NA) was analyzed in F1 females to assess LPS-induced neuroinflammation. KEY FINDINGS Prenatal LPS did not change open field behavior but impaired both maternal and maternal aggressive behaviors in the F1 generation. LPS exposure also reduced both striatal levels of dopamine and serotonin and its metabolites, but induced no changes in NA astrocyte expression. SIGNIFICANCE We suggested that the observed impairments in the F1 females were a consequence of a motivational change induced by prenatal LPS, as (1) no changes in motor activity were observed, (2) prenatal LPS-exposure was reported by our group to induce motivational impairments in males, and (3) the existence of a strong connection between striatal dopaminergic activity and motivation-oriented activities. The present findings strongly indicate a maternal effect for prenatal LPS, at least for the F1 generation.

Infecção experimental pelo Encephalitozoon cuniculi em camundongos imunossuprimidos com dexametasona

OBJECTIVE: Microsporidian Encephalitozoon cuniculi has been recognized as an opportunistic pathogen in immunosuppressed individuals, such as AIDS patients. The objective of the study was to develop pharmacologically immunosuppressed animals as a model of the natural occurring E. cuniculi infection. METHODS: Distint groups of adult Balb-C mice were immunosuppressed with different doses of dexamethasone (Dx, 3 or 5 mg/kg/day, intraperitoneal route - IP) and inoculated with E. cuniculi spores by IP route intraperitoneally. Control groups (inoculated animals but non-immunosuppressed and non- inoculated animals but immunosuppressed) were also used. The spores of E. cuniculi were previously cultivated in MDCK cells. The animals were sacrificed and necropsied at 7, 14, 21, 28 and 35 days post-inoculation. Tissue fragments were collected and processed for light microscopy studies, using Gram-chromotrope and hematoxylin-eosin staining techniques. RESULTS: In all immunosupressed and inoculated inoculated immunosuppressed mice,specially in those that received 5 mg/kg/day of dexamethasone, the most prominent necropsy findings were hepatomegaly and splenomegaly. The experimental inoculation resulted in a disseminated non-lethal infection, characterized by granulomatous lesions in several organs (liver, lungs, kidneys, gut and brain) but notably in the hepatic tissue. Spores of E. cuniculi were only seen in few animals treated with 5 mg/kg/day of Dx at 35 days post-infection. CONCLUSIONS: Microsporidiosis in Dx-immunosuppressed mice provides a useful model for studies of the microsporidial infection, resembling that one naturally occurring in immunodeficient individuals with AIDS.

Estudo da imunorreatividade astrocitária para GFAP e vimentina no tronco encefálico de ratos Wistar submetidos ao modelo gliotóxico do brometo de etídio

BACKGROUND Ethidium bromide (EB) is known as a gliotoxic agent that causes focal astrocytic and oligodendroglial disappearance. OBJECTIVE Astrocyte immunoreactivity to glial fibrillary acidic protein (GFAP) and vimentin (VIM) was investigated after EB injection. METHOD Adult male Wistar rats were taken as histologic controls (group H) or injected into cisterna pontis with 0.1% EB (group E) or 0.9% saline solution (group C). Brainstem samples were collected from 24 hours to 31 days post-injection for GFAP and VIM immunohistochemical staining using avidin-biotin method. RESULTS In group E, extensive lesions were seen in the pons and mesencephalon, with astrocyte disappearance from the central area 24 hours post-injection. Macrophagic infiltration and peripheral astrocytic reaction were noted after 3 days. Marginal astrocytes presented increased immunoreactivity to GFAP and reexpression of VIM, the last one confined to the edges of the injury site. In group C, discrete pontine lesions were observed, showing central astrocyte preservation and a peripheral GFAP staining less intense comparing to group E. No immunoreactivity to VIM was noted in such astrocytes. CONCLUSION Astrocytes from the edges of the EB-induced lesions presented increased immunoreactivity to GFAP and reexpression of VIM.

Ocorrência de Giardia, Cryptosporidium e microsporídios em animais silvestres em área de desmatamento no Estado de São Paulo, Brasil

The occurrence of Giardia, Cryptosporidium and microsporidia was investigated in 98 faecal specimens from wildlife animals, captured in an area of deforestation for the construction of two water reservoirs (Paraitinga and Biritiba), located in the municipalities of Mogi das Cruzes, Salesopolis and Biritiba-Mirim, in the state of Sao Paulo (Brazil). Samples were obtained from 46 rodents, 21 marsupials, 16 frogs, 9 bats, 3 tamarins and 3 lizards. For the detection of Giardia, Cryptosporidium and microsporidia it was used, respectively, the floatation technique with lead sulphate, the Kinyoun method and the Gram-Chromotrope staining. The total number of parasitized animals by one of these protozoans was 17.35% (17/98). Cysts of Giardia were found in faecal samples from 2 prehensile-tailed porcupines (Coendou villosus). The three positive animals for Cryptoporidium were rodents - 1 montane akodont (Akodon montensis), 1 ebony akodont (Thaptomyces nigrita) and 1 guainan squirrel (Sciurus aestuans). Microporidia spores were seen in the stools of 12 animals - 6 small rodents, including 3 montane akodonts, 1 prehensile-tailed porcupine and 2 pigmy rice rats (Oligoryzomys sp.); 3 marsupials, including 1 gray slender mouse opossum (Marmosops incanus) and 2 big eared opossums (Didelphis aurita); 3 hairy-legged vampire bats (Diphylla ecaudata). This is the first description of microsporidiosis in wildlife animals in Brazil. The present study emphasizes the importance of these animals, particularly small mammals, as potential sources of protozoan infection to other animal populations, including man, in areas of deforestation.

Marcação imunoistoquímica da expressão astrocitária de proteína glial fibrilar ácida e de vimentina no sistema nervoso central de cães com cinomose

Considering that many aspects involved in the pathogenesis of the central nervous system (CNS) demyelinating diseases are still poorly understood and that astrocytes seem to mediate such processes, this study analyzed the participation of astrocytes in the demyelinating processes of CNS by using immunohistochemical staining of two astrocytic proteins--glial fibrillary acidic protein (GFAP) and vimentin (VIM)--comparing samples of cerebellum and brainstem from eight dogs with canine distemper and from two healthy dogs, from different breeds and ages varying from 1 to 4 years old. Histological sections were submitted to the avidin-biotin-peroxidase indirect method of immunohistochemical staining (ABC) and the astrocytic reactivity, observed in light microscopy, was quantified in a computer system for image analysis. It was possible to notice, on most of the sections from sick animals, degenerative lesions that indicate demyelination. The immunostaining for GFAP and VIM was more intense on animals with canine distemper, specially around the ventricules and near degenerated sites. There was no significant difference between the immunostaining (GFAP and VIM) of animals with canine distemper with and without inflammatory infiltrate of the cerebellar white matter. The increased immunoreactivity of astrocytes for GFAP and the VIM reexpression in injured areas indicate the astrocytic involvement on nervous tissue response to the demyelinating lesions induced by the canine distemper virus (CDV) in the CNS.