Estudo das alterações neuropatológicas e do comportamento em tarefas hipocampo-dependentes induzidas pela encefalite experimental aguda associada ao vírus piry

Este trabalho investiga as alterações neuropatológicas e do comportamento em tarefas hipocampo-dependentes induzidas pela encefalite experimental aguda associada ao vírus Piry. Três janelas temporais (3, 7 e 10 dias após a inoculação) foram avaliadas e dois ambientes testados de forma a avaliar se o enriquecimento ambiental influencia as alterações associadas à infecção. Camundongos fêmeas de dois meses de idade foram mantidos em ambientes empobrecido (IE) ou enriquecido (EE) durante seis meses e foram testados para as atividades de burrowing, de campo aberto e de discriminação olfatória. Após esse período os animais foram inoculados por via intranasal com 5μl de homogenado de cérebro normal (NBH) ou homogenado de cérebro infectado pelo vírus Piry (PY) e então reorganizados nos seguintes grupos: IENBH, IEPY, EENBH e EEPY, com sete animais cada. Três, sete e dez dias após a inoculação (dpi), os animais de cada janela temporal foram perfundidos com fixador aldeídico. Os encéfalos foram removidos, seccionados e as secções foram processadas para imunohistoquímica para anti-Piry e para anti-Iba-1 para marcação dos antígenos virais e de macrófagos/micróglias, respectivamente. Quantificações estereológicas foram feitas em cada camada celular de CA3 usando o método do fracionador óptico. Estimativas do fracionador óptico mostraram que não houve alteração da estimativa do número total de micróglias em CA3 nos grupos analisados, indicando que a infecção não alterou o número de células, mas a morfologia das micróglias, que se mostraram mais ativadas no grupo IEPY do que no grupo EEPY. Os resultados revelaram a presença de antígenos virais no bulbo olfatório, córtex piriforme, estriado e fimbria, ao longo da via olfatória. A atividade de burrowing no grupo IEPY diminuiu na primeira janela temporal e permaneceu baixa até a última janela, enquanto que no grupo EEPY não houve alteração neste teste. Na atividade de campo aberto, o grupo IEPY aumentou o tempo imóvel já na primeira janela e continuou aumentando até a última; reduziu o número de linhas cruzadas na segunda janela e permaneceu reduzido na última; e diminuiu o tempo na zona central na segunda e última janela. Já o grupo EEPY, aumentou o tempo imóvel e reduziu o número de linhas cruzadas na segunda janela. No teste de discriminação olfatória, o principal grupo afetado foi o grupo IEPY, que não discriminou os dois odores na última janela, enquanto que o grupo EEPY não teve alteração na discriminação.

Phenotypic and genotypic features of Aggregatibacter actinomycetemcomitans isolated from patients with periodontal disease

Aggregatibacter actinomycetemcomitans is strongly implicated in the pathogenesis of periodontitis. In this study, the phenotypic and genotypic features of A. actinomycetemcomitans and the presence of genes involved in toxicity were determined. Sixty-five patients with periodontal pocket and 48 healthy subjects were evaluated. Biotyping, adherence and invasion, neuraminidase and biofilm production, presence of capsule and fimbria, as well as the presence of flp-1, apaH, ltx, and cdt genes were determined. Biotype II was the most prevalent. Sixty-six strains were adherent and 33 of them were able to invade KB cells. Sixty strains produced neuraminidase, and 55 strains biofilms. Strains showed capsule but not fimbriae. Forty-six strains were cytotoxic, and most strains harbored the apaH and flp-1 genes. LTX promoter and the ltxA gene were observed in all strains from periodontal patients. The cdtA gene was observed in 50 (71.4%) strains, cdtB in 48 (68.6%) strains, cdtC in 60 (85.7%), and cdtABC in 40 (57.1%) strains. The presence of A. actinomycetemcomitans harboring the cdtC gene from healthy subjects may represent a transitory microorganism in the oral microbiota. More studies are necessary to understand the real role of this microorganism in the pathogenesis of periodontal disease

AN ELECTROPHYSIOLOGICAL ANALYSIS OF THE AMYGDALOID AND SUBICULAR PROJECTIONS TO THE VENTROMEDIAL NUCLEUS OF THE HYPOTHALAMUS IN THE RABBIT

Electrophysiological experiments were performed on 96 male New Zealand white rabbits, anesthetized with urethane. Glass electrodes, filled with 2M NaCl, were used for microstimulation of three fiber pathways projecting from "limbic" centers to the ventromedial nucleus of the hypothalamus (VMH). Unitary and field potential recordings were made in the VMH after stimulation.^ Stimulation of the lateral portion of the fimbria, which carries fibers from the ventral subiculum of the hippocampal formation, evokes predominantly an inhibition of neurons medially in the VMH, and excitation of neurons located laterally.^ Stimulation of the dorsal portion of the stria terminalis, which carries fibers from the cortical nucleus of the amygdala, also produces predominantly an inhibition of cells medially and excitation laterally.^ Stimulation of the ventral component of the stria terminalis, which carries fibers from the medial nucleus of the amygdala, evokes excitation of cell medially, with little or no response seen laterally.^ Cells recorded medially in the VMH received convergent inputs from each of the three fiber systems: inhibition from fimbria and dorsal stria stimulation, excitation from ventral stria stimulation.^ The excitatory unitary responses recorded medially to ventral stria stimulation and laterally to fimbria and dorsal stria stimulation were subjected to a series of threshold stimulus intensities. From these tests it was determined that each of these three projections terminates monosynaptically on VMH neurons.^ The evidence for convergence upon single VMH neurons of projections from the amygdala and the hippocampal formation suggests this area of the brain to be important for integration of information from these two limbic centers. The VMH has been implied in a number of behavioral states: eating, reproduction, defense and aggression; it has further been linked to control of the anterior pituitary. These data provide a functional circuit through which the amygdaloid complex and the hippocampal formation can channel information from higher cortical centers into a hypothalamic area capable of coordinating behavioral and hormonal responses. ^

Radiolarian biostratigraphy and chronology of radiolarian events of ODP Leg 199 sites and EW9709 sediment cores

A generally rich radiolarian fauna ranging in age from Quaternary to early Eocene (Zone RP7) was found at five of the eight sites drilled during Ocean Drilling Program (ODP) Leg 199. Of particular interest are the stratigraphically complete assemblages that range in age from middle Miocene (Zone RN5) to early Eocene (Zone RP7), composites of Sites 1218, 1219, and 1220. At the same sites, multisensor track (MST) data show consistent cycles in gamma ray attenuation density, color, and carbonate content that can be correlated on a submeter scale from the early Miocene to early Eocene. In addition, the magnetic reversal records from these three sites allow construction of an absolute timescale. A series of 305 radiolarian morphologic first and last occurrences and evolutionary transitions for radiolarians were determined and correlated directly with the accompanying MST and paleomagnetic data, resulting in a detailed and accurate dating of events. Since many of the bioevents are found at more than one site, it was also possible to test their reliability within the study area. Twelve new species are described: Calocycletta (Calocycletta) anekathen, Dorcadospyris anastasis, Dorcadospyris copelata, Dorcadospyris cyclacantha, Dorcadospyris ombros, Dorcadospyris scambos, Eucyrtidium mitodes, Theocyrtis careotuberosa, Theocyrtis perpumila, Theocyrtis perysinos, Theocyrtis setanios, and Thyrsocyrtis (Pentalacorys) orthotenes.

Presence-absence species/sample matrix for the measured sections at the area of Maghara, North Sinai, Egypt

As age-diagnostic fossils are rare in the Middle to Upper Jurassic sedimentary succession of Gebel Maghara, North Sinai, Egypt, and in order to ensure maximal stratigraphic resolution, chronostratigraphic boundaries were determined based on quantitative biostratigraphy. A data matrix comprising 231 macrofaunal taxa in 93 samples from four sections has been processed with the Unitary Association (UA) Method. This led to construction of a sequence of 29 UAs (maximal sets of actually or virtually coexisting taxa), which have been grouped into 14 laterally reproducible association zones. The UA method allowed an in-depth analysis of the stratigraphically conflicting taxa, enabled the biostratigraphic subdivision of the studied interval, and also provided stratigraphic correlation among the measured sections and with the Tethyan ammonite zones.

Detection of neuritic plaques in Alzheimer’s disease by magnetic resonance microscopy

Magnetic resonance microscopy (MRM) theoretically provides the spatial resolution and signal-to-noise ratio needed to resolve neuritic plaques, the neuropathological hallmark of Alzheimer’s disease (AD). Two previously unexplored MR contrast parameters, T2* and diffusion, are tested for plaque-specific contrast to noise. Autopsy specimens from nondemented controls (n = 3) and patients with AD (n = 5) were used. Three-dimensional T2* and diffusion MR images with voxel sizes ranging from 3 × 10−3 mm3 to 5.9 × 10−5 mm3 were acquired. After imaging, specimens were cut and stained with a microwave king silver stain to demonstrate neuritic plaques. From controls, the alveus, fimbria, pyramidal cell layer, hippocampal sulcus, and granule cell layer were detected by either T2* or diffusion contrast. These structures were used as landmarks when correlating MRMs with histological sections. At a voxel resolution of 5.9 × 10−5 mm3, neuritic plaques could be detected by T2*. The neuritic plaques emerged as black, spherical elements on T2* MRMs and could be distinguished from vessels only in cross-section when presented in three dimension. Here we provide MR images of neuritic plaques in vitro. The MRM results reported provide a new direction for applying this technology in vivo. Clearly, the ability to detect and follow the early progression of amyloid-positive brain lesions will greatly aid and simplify the many possibilities to intervene pharmacologically in AD.

Análise de expressão gênica de Xylella fastidiosa cultivada em diferentes concentrações de glicose pela técnica de microarrays de DNA

Xylella fastidiosa (Xf) é o agente etiológico causador de doenças em uma grande variedade de cultivos de grande importância econômica, causando a c1orose variegada dos citros, uma das doenças mais danosas à indústria de citros no Brasil. Os genomas de algumas cepas deste fitopatógeno foram completamente seqüenciados promovendo assim estudos funcionais do genoma em larga escala. Neste trabalho nós nos propusemos a investigar o perfil de transcrição de Xf através da técnica microarranjos (no título da dissertação microarrays, mas a partir de agora usaremos microaarranjos) de DNA usando todo o genoma do fitopatógeno e cultivando-a sob meio definido variando a concentração de glicose. O objetivo inicial deste trabalho era observar se Xf comportava-se da mesma forma que Xac, que tem a expressão de goma aumentada devido ao aumento da concentração de glicose do meio. Nossas análises revelaram que enquanto os transcritos relacionados à goma não se mostraram afetados com a concentração de glicose, genes que codificam para análogos a Colicina-V e precursores de fimbria foram induzidos em alta concentração de glicose. Baseados nestes resultados, nós propusemos um modelo de mecanismo de produção e defesa contra a Colicina em Xf.