Alexandre Moraes Pinheiro

Freqüência de cães reagentes para Neospora caninum em São Luís, Maranhão

The frequency of antibodies to Neospora caninum (Protozoa: Apicomplexa) in dog sera was investigated. Blood samples from 100 mongrel dogs, captured in the streets of Sao Luis, State of Maranhao, were analized using imunofluorescent antibody test. Forty five percent of the dogs were positive, and the titers ranged from 1:50 to 1:800. No sex difference was observed for frequency of N. caninum (60% in males and 40% in females). This is the first report of antibodies to N. caninum in dogs from Maranhao.

Effects of IFN-γ, TNF-α, IL-10 and TGF-β on Neospora caninum infection in rat glial cells

Neospora caninum causes abortion in cattle and neurological disorders in dogs. The immunological response to this parasite has been described as predominantly of the Th1 type. However, infected primary glial cell cultures release IL-10 and IL-6 but not IFN-γ. This suggests a rather protective response of the glia to avoid inflammatory damage of the nervous tissue. In this study, we investigated the effects of pro-inflammatory cytokines in primary mixed cultures of rat astrocytes and microglia infected with N. caninum. The cells were treated with either IFN-γ, TNF-α, anti-IL-10 or anti-TGF-β antibodies and were infected with parasite tachyzoites 24h later. Trypan Blue exclusion and MTT assays were performed to test cell viability. It was observed that cytokines, antibody treatment and in vitro infection did not reveal significant cell death in the various culture conditions. Treatment with 50, 150 and 300 IU/mL of either IFN-γ or TNF-α reduced tachyzoites numbers in cultures by 36.7%, 54.8% and 63.8% for IFN-γ and by 27.6%, 38.4% and 29.7% for TNF-α, respectively. In the absence of IL-10 and TGF-β, tachyzoite numbers were reduced by 52.8% and 41.5%, respectively. While IFN-γ (150 and 300 IU/mL) increased the nitrite levels in uninfected cells, parasite infection seemed to reduce the nitrite levels, and this reduction was more expressive in IFN-γ-infected cells, thereby suggesting an inhibitory effect on its production. However, TNF-α, IL-10 and TGF-β did not affect the nitrite levels. Basal PGE(2) levels also increased by 17% and 25%; 78% and 13% in uninfected and infected cells treated with IFN-γ or anti-TGF-β, respectively. Nevertheless, the antibody neutralization of IL-10 reduced PGE(2) release significantly. These results highlight the possibility of a combined effect between the IFN-γ and parasite evasion strategies and show that the IFN-γ, TNF-α, IL-10 and TGF-β cytokines participate in parasite proliferation control mechanisms.

Role of IFN-γ and LPS on neuron/glial co-cultures infected by Neospora caninum

Neospora caninum causes cattle abortion and neurological symptoms in dogs. Although infection is usually asymptomatic, classical neurological symptoms of neosporosis may be associated with encephalitis. This parasite can grow in brain endothelial cells without markedly damages, but it can modulate the cellular environment to promote its survival in the brain. In previous studies, we described that IFN-γ decreased the parasite proliferation and down regulated nitric oxide (NO) production in astrocyte/microglia cultures. However, it remains unclear how glial cells respond to N. caninum in the presence of neurons. Therefore, we evaluated the effect of 300 IU/mL IFN-γ or 1.0 mg/mL of LPS on infected rat neuron/glial co-cultures. After 72 h of infection, LPS did not affect the mitochondrial dehydrogenase activity. However, IFN-γ decreased this parameter by 15.5 and 12.0% in uninfected and infected cells, respectively. The number of tachyzoites decreased 54.1 and 44.3% in cells stimulated with IFN-γ and LPS, respectively. Infection or LPS treatment did not change NO production. On the other hand, IFN-γ induced increased nitrite release in 55.7%, but the infection reverted this induction. IL-10 levels increased only in infected cultures (treated or not), meanwhile PGE2 release was improved in IFN-γ/infected or LPS/infected cells. Although IFN-γ significantly reduced the neurite length in uninfected cultures (42.64%; p < 0.001), this inflammatory cytokine reverted the impairment of neurite outgrowth induced by the infection (81.39%). The results suggest a neuroprotective potential response of glia to N. caninum infection under IFN-γ stimulus. This observation contributes to understand the immune mediated mechanisms of neosporosis in central nervous system (CNS).

Aspectos Metodológicos do Comportamento Ingestivo de Vacas Leiteiras Não Gestantes Mantidas em Pastagens

Objetivou-se identificar os intervalos de tempo mais adequados para estudo do comportamento ingestivo de vacas leiteiras nao gestantes a pasto. O experimento foi conduzido em uma fazenda localizada no municipio de Santo Antonio de Jesus, situada no Reconcavo do estado da Bahia. A avaliacao do comportamento foi de 16 a 18 de janeiro de 2009. Foram utilizadas oito vacas leiteiras mesticas devidamente numeradas. Cada animal foi observado em cinco diferentes escalas de intervalo: cinco, 10, 15, 20 e 30 minutos, por dois periodos integrais de 24 horas. Foram determinadas as atividades de alimentacao, ruminacao, ruminacao deitado, ocio, ocio deitado, frequencia de alimentacao, frequencia de ruminacao e frequencia de ocio. Para as variaveis alimentacao, ruminacao, ruminacao deitado, ocio, ocio deitado nao foram verificados diferencas entre os intervalos de observacoes 10, 15, 20 e 30 minutos, quando comparados com o intervalo de observacao de cinco minutos (P<0,05). No entanto, para frequencia de alimentacao e de ocio houve diferencas entre o intervalo de observacao de cinco minutos, quando comparados com os demais. Para estudos das atividades do comportamento ingestivo de vacas leiteiras nao gestantes a pasto, as observacoes podem ser realizados em ate 30 minutos de intervalo. No entanto, para as frequencias das atividades, as observacoes devem ser feitas em ate cinco minutos. A luminosidade influencia o comportamento e a frequencia das atividades de ingestao, ruminacao e ocio.