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Search Results: 1 - 10 of 189939 matches for " Cristovam W Pican?o; "
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Single-pass measurement of the optical quality of the opossum eye
Oswaldo-Cruz, Eduardo;Picano-Diniz, Cristovam W.;Silveira, Luiz Carlos L.;
Psychology & Neuroscience , 2011, DOI: 10.3922/j.psns.2011.1.002
Abstract: this paper reports the results that are part of a series of experiments designed to evaluate aspects of the spatial resolution of the visual system of the opossum, didelphis marsupialis aurita. this nocturnal marsupial presents a well-developed eye, displaying features that reflect specialization for operation at low levels of luminosity. the species was shown to be slightly myopic, a feature that may prove to be valuable because of the increased depth of field. opossum visual acuity has been previously evaluated by means of determining the contrast sensitivity function (csf). the results indicate rather poor visual acuity compared with other nocturnal animals. in this paper, we describe the results obtained for the optical quality of the opossum's eye using a single-pass method. the results suggest that the opossum's optical system is capable of forming images that can be resolved when separated by an angular distance on the order of 6 minutes of arc.
Single-pass measurement of the optical quality of the opossum eye
Eduardo Oswaldo-Cruz,Cristovam W. Picano-Diniz,Luiz Carlos L. Silveira
Psychology & Neuroscience , 2011,
Abstract: This paper reports the results that are part of a series of experiments designed to evaluate aspects of the spatial resolution of the visual system of the opossum, Didelphis marsupialis aurita. This nocturnal marsupial presents a well-developed eye, displaying features that refect specialization for operation at low levels of luminosity. The species was shown to be slightly myopic, a feature that may prove to be valuable because of the increased depth of feld. Opossum visual acuity has been previously evaluated by means of determining the Contrast Sensitivity Function (CSF). The results indicate rather poor visual acuity compared with other nocturnal animals. In this paper, we describe the results obtained for the optical quality of the opossum’s eye using a single-pass method. The results suggest that the opossum’s optical system is capable of forming images that can be resolved when separated by an angular distance on the order of 6 minutes of arc.
Cortical representation of the horizon in V1 and peripheral scaling in mammals with lateral eyes
Cristovam W. Picano-Diniz,Emiliana G. Rocha,Luiz Carlos L. Silveira,Guy Elston
Psychology & Neuroscience , 2011,
Abstract: n the present investigation we mapped the primary visual area of the South American diurnal rodent, Dasyprocta aguti, by standardized electrophysiological mapping techniques. In particular, we performed a series of mapping experiments of the visual streak in the primary visual cortex. We found that the representation of the visual streak in V1 is greatly expanded, the nasal 10 degrees of the visual streak representation occupies ten times more cortical area than equivalent areas in the central or temporal representation. Comparison of these data with those on the density of ganglion cells in the retina at corresponding locations in the visual feld reveal a signifcant mismatch between these two variables. The nasal representation is greatly expanded along the horizontal meridian in V1 as compared to the central and temporal regions whereas the density of ganglion cells decreases with progression along the visual streak from central region towards the nasal or temporal visual feld. A review of the available data reveals that all lateral-eyed mammals exhibit a similar mismatch between the retinal and cortical representation of the visual feld, and this mismatches is greater in those species with well defned visual streaks such as rabbit and agouti.
Cortical representation of the horizon in V1 and peripheral scaling in mammals with lateral eyes
Picano-Diniz, Cristovam W.;Rocha, Emiliana G.;Silveira, Luiz Carlos L.;Elston, Guy;Oswaldo-Cruz, Eduardo;
Psychology & Neuroscience , 2011, DOI: 10.3922/j.psns.2011.1.004
Abstract: in the present investigation we mapped the primary visual area of the south american diurnal rodent, dasyprocta aguti, by standardized electrophysiological mapping techniques. in particular, we performed a series of mapping experiments of the visual streak in the primary visual cortex. we found that the representation of the visual streak in v1 is greatly expanded, the nasal 10 degrees of the visual streak representation occupies ten times more cortical area than equivalent areas in the central or temporal representation. comparison of these data with those on the density of ganglion cells in the retina at corresponding locations in the visual field reveal a significant mismatch between these two variables. the nasal representation is greatly expanded along the horizontal meridian in v1 as compared to the central and temporal regions whereas the density of ganglion cells decreases with progression along the visual streak from central region towards the nasal or temporal visual field. a review of the available data reveals that all lateral-eyed mammals exhibit a similar mismatch between the retinal and cortical representation of the visual field, and this mismatches is greater in those species with well defined visual streaks such as rabbit and agouti.
Os dilemas do desenvolvimento científico e tecnológico brasileiro
Diniz Cristovam Wanderley Picano
Ciência & Saúde Coletiva , 2004,
Abstract:
Enriched environment contributes to recovery of visual acuity and increases perineuronal nets in monocular-deprived animals
Trévia, Nonata;Almeida, Izabela N. F.;Oliveira, Poliana S.;Warwick, Laura V.;Marques, Viviane;Santos, Denise C. dos;Paulo, Dario C.;Viegas, Maria L.;Picano-Diniz, Cristovam W.;
Psychology & Neuroscience , 2011, DOI: 10.3922/j.psns.2011.1.006
Abstract: the aim of the present study was to analyze the influence of enriched environment on the distribution of perineuronal nets (pnns) using a stereogically based unbiased protocol and visual acuity in adult swiss albino mice that underwent monocular deprivation during the critical period of postnatal development. eight female swiss albino mice were monocular deprived on postnatal day 10 and divided into two groups at weaning: standard environment (se group, n = 4) and enriched environment (ee group, n = 4). after 3 months, all of the mice were subjected to grating visual acuity tests, sacrificed, and perfused with aldehyde fixative. the brains were removed and cut at 70 μm thickness in a vibratome and processed for lectin histochemical staining with wisteria floribunda agglutinin (wfa). architectonic limits of area 17 were conspicuously defined by wfa histochemical staining, and the optical fractionator stereological method was applied to estimate the total number of pnns in the supragranular, granular, and infragranular layers. all groups were compared using student's t-test at a 95% confidence level. comparative analysis of the average pnn estimations revealed that the ee group had higher pnns in the supragranular layer (2726.33 ± 405.416, mean ± standard deviation) compared with the se group (1543.535 ± 260.686; student's t-test, p = .0495). no differences were found in the other layers. visual acuity was significantly lower in the se group (0.55 cycles/degree) than in the ee group (1.06 cycles/degree). our results suggest that the integrity of the specialized extracellular matrix pnns of the supragranular layer may be essential for normal visual acuity development.
Environmental influences on antibody-enhanced dengue disease outcomes
Diniz, Daniel Guerreiro;F?ro, César Augusto Raiol;Turiel, Maíra C Pereira;Sosthenes, Marcia CK;Demachki, Samia;Gomes, Giovanni Freitas;Rego, Carla M Damasceno;Magalh?es, Marina Cutrim;Pinho, Brunno Gomes;Ramos, Juliana Pastana;Casseb, Samir M Moraes;Brito, Maysa de Vasconcelos;Silva, Eliana Vieira Pinto da;Nunes, Marcio Roberto Teixeira;Diniz, José Antonio Picano;Cunningham, Colm;Perry, Victor Hugh;Vasconcelos, Pedro F Costa;Diniz, Cristovam W Picano;
Memórias do Instituto Oswaldo Cruz , 2012, DOI: 10.1590/S0074-02762012000800010
Abstract: because an enriched environment (ee) enhances t-cell activity and t-lymphocytes contribute to immunopathogenesis during heterologous dengue virus (denv) infections, we hypothesised that an ee increases dengue severity. to compare single serotype (ss) and antibody-enhanced disease (aed) infections regimens, serial intraperitoneal were performed with denv3 (genotype iii) infected brain homogenate or anti-denv2 hyperimmune serum followed 24 h later by denv3 (genotype iii) infected brain homogenate. compared aed for which significant differences were detected between the ee and impoverished environmental (ie) groups (kaplan-meyer log-rank test, p = 0.0025), no significant differences were detected between the ss experimental groups (kaplan-meyer log-rank test, p = 0.089). survival curves from ee and ie animals infected with the aed regimen were extended after corticoid injection and this effect was greater in the ee than in the ie group (kaplan-meyer log-rank test, p = 0.0162). under the aed regimen the ee group showed more intense clinical signs than the ie group. dyspnoea, tremor, hunched posture, ruffled fur, immobility, pre-terminal paralysis, shock and death were associated with dominant t-lymphocytic hyperplasia and presence of viral antigens in the liver and lungs. we propose that the increased expansion of these memory t-cells and serotype cross-reactive antibodies facilitates the infection of these cells by denv and that these events correlate with disease severity in an ee.
Differential vulnerability of substantia nigra and corpus striatum to oxidative insult induced by reduced dietary levels of essential fatty acids
Henriqueta D. Cardoso,Priscila P. Passos,Claudia J. Lagranha,Anete C. Ferraz,Eraldo F. Santos Júnior,Rafael S. Oliveira,Pablo E. L. Oliveira,Rita de C. F. Santos,David F. Santana,Juliana M. C. Borba,Ana P. Rocha-de-Melo,Rubem C. A. Guedes,Daniela M. A. F. Navarro,Geanne K. N. Santos,Roseane Borner,Cristovam W. Picano-Diniz,Eduardo I. Beltr?o,Janilson F. Silva,Marcelo C. A. Rodrigues,Belmira L. S. Andrade da Costa
Frontiers in Human Neuroscience , 2012, DOI: 10.3389/fnhum.2012.00249
Abstract: Oxidative stress (OS) has been implicated in the etiology of certain neurodegenerative disorders. Some of these disorders have been associated with unbalanced levels of essential fatty acids (EFA). The response of certain brain regions to OS, however, is not uniform and a selective vulnerability or resilience can occur. In our previous study on rat brains, we observed that a two-generation EFA dietary restriction reduced the number and size of dopaminergic neurons in the substantia nigra (SN) rostro-dorso-medial. To understand whether OS contributes to this effect, we assessed the status of lipid peroxidation (LP) and anti-oxidant markers in both SN and corpus striatum (CS) of rats submitted to this dietary treatment for one (F1) or two (F2) generations. Wistar rats were raised from conception on control or experimental diets containing adequate or reduced levels of linoleic and α-linolenic fatty acids, respectively. LP was measured using the thiobarbituric acid reaction method (TBARS) and the total superoxide dismutase (t-SOD) and catalase (CAT) enzymatic activities were assessed. The experimental diet significantly reduced the docosahexaenoic acid (DHA) levels of SN phospholipids in the F1 (~28%) and F2 (~50%) groups. In F1 adult animals of the experimental group there was no LP in both SN and CS. Consistently, there was a significant increase in the t-SOD activity (p < 0.01) in both regions. In EF2 young animals, degeneration in dopaminergic and non-dopaminergic neurons and a significant increase in LP (p < 0.01) and decrease in the CAT activity (p < 0.001) were detected in the SN, while no inter-group difference was found for these parameters in the CS. Conversely, a significant increase in t-SOD activity (p < 0.05) was detected in the CS of the experimental group compared to the control. The results show that unbalanced EFA dietary levels reduce the redox balance in the SN and reveal mechanisms of resilience in the CS under this stressful condition.
Spatial memory decline after masticatory deprivation and aging is associated with altered laminar distribution of CA1 astrocytes
Marina Frota de Almeida, Fabíola de Siqueira Mendes, André Gurgel Felício, Manoela Falsoni, Márcia Ferreira de Andrade, Jo?o Bento-Torres, Pedro da Costa Vasconcelos, Victor Perry, Cristovam Picano-Diniz, Marcia Kronka Sosthenes
BMC Neuroscience , 2012, DOI: 10.1186/1471-2202-13-23
Abstract: Eating a SD variably affected the number of astrocytes in the CA1 hippocampal field, and SD mice performed worse on water maze memory tests than HD mice. Three-month-old mice in both groups could remember/find a hidden platform in the water maze. However, 6-month-old SD mice, but not HD mice, exhibited significant spatial memory dysfunction. Both SD and HD 18-month-old mice showed spatial memory decline. Older SD mice had astrocyte hyperplasia in the strata pyramidale and oriens compared to 6-month-old mice. Aging induced astrocyte hypoplasia at 18 months in the lacunosum-moleculare layer of HD mice.Taken together, these results suggest that the impaired spatial learning and memory induced by masticatory deprivation and aging may be associated with altered astrocyte laminar distribution and number in the CA1 hippocampal field. The underlying molecular mechanisms are unknown and merit further investigation.Previous studies have established an association between chewing activity and cognition [1-3]. The systemic effects of long-term masticatory imbalances are associated with neurodegeneration and are a risk factor for senile dementia in humans [4] and memory deficits in experimental animals [5]. To investigate the impact of masticatory imbalances on various activities and physiological factors, experimental masticatory deprivation has been modelled experimentally in animals using a modified diet [6], molar removal [7,8], or occlusion disharmony modelled by "bite-raised" condition [9,10]. These approaches revealed that masticatory dysfunction reduces spatial learning and memory in water maze tests in rats [8,11] and mice [11-13], and that these deficits seem to increase with aging and time after tooth loss [8]. Induced molarless subjects, revealed reduced neurogenesis in young rats [14], and there is a loss of astrocytes, neurons and dendritic spines in the hippocampus of aged rats and mice [7,14,15]. Young mice fed a soft diet show reduced neurogenesis and BDNF level
Influence of Enriched Environment on Viral Encephalitis Outcomes: Behavioral and Neuropathological Changes in Albino Swiss Mice
Aline Andrade de Sousa,Renata Reis,Jo?o Bento-Torres,Nonata Trévia,Nara Alves de Almeida Lins,Aline Passos,Zaire Santos,José Antonio Picano Diniz,Pedro Fernando da Costa Vasconcelos,Colm Cunningham,Victor Hugh Perry,Cristovam Wanderley Picano Diniz
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015597
Abstract: An enriched environment has previously been described as enhancing natural killer cell activity of recognizing and killing virally infected cells. However, the effects of environmental enrichment on behavioral changes in relation to virus clearance and the neuropathology of encephalitis have not been studied in detail. We tested the hypothesis that environmental enrichment leads to less CNS neuroinvasion and/or more rapid viral clearance in association with T cells without neuronal damage. Stereology-based estimates of activated microglia perineuronal nets and neurons in CA3 were correlated with behavioral changes in the Piry rhabdovirus model of encephalitis in the albino Swiss mouse. Two-month-old female mice maintained in impoverished (IE) or enriched environments (EE) for 3 months were behaviorally tested. After the tests, an equal volume of Piry virus (IEPy, EEPy)-infected or normal brain homogenates were nasally instilled. Eight days post-instillation (dpi), when behavioral changes became apparent, brains were fixed and processed to detect viral antigens, activated microglia, perineuronal nets, and T lymphocytes by immuno- or histochemical reactions. At 20 or 40 dpi, the remaining animals were behaviorally tested and processed for the same markers. In IEPy mice, burrowing activity decreased and recovered earlier (8–10 dpi) than open field (20–40 dpi) but remained unaltered in the EEPy group. EEPy mice presented higher T-cell infiltration, less CNS cell infection by the virus and/or faster virus clearance, less microgliosis, and less damage to the extracellular matrix than IEPy. In both EEPy and IEPy animals, CA3 neuronal number remained unaltered. The results suggest that an enriched environment promotes a more effective immune response to clear CNS virus and not at the cost of CNS damage.
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