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Search Results: 1 - 10 of 132820 matches for " Eduardo;Pican?o-Diniz "
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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
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.
Horizontal projections of area 17 in Cebus monkeys: metric features, and modular and laminar distribution
Amorim, A.K.J.;Picano-Diniz, C.W.;
Brazilian Journal of Medical and Biological Research , 1997, DOI: 10.1590/S0100-879X1997001200018
Abstract: metric features and modular and laminar distributions of intrinsic projections of area 17 were studied in cebus apella. anterogradely and retrogradely labeled cell appendages were obtained using both saturated pellets and iontophoretic injections of biocytin into the operculum. laminar and modular distributions of the labeled processes were analyzed using nissl counterstaining, and/or cytochrome oxidase and/or nadph-diaphorase histochemistry. we distinguished three labeled cell types: pyramidal, star pyramidal and stellate cells located in supragranular cortical layers (principally in layers iiia, iiib $mvd$:face("symbol") a, iiib ? and iiic). three distinct axon terminal morphologies were found, i.e., ia, ib and ii located in granular and supragranular layers. both complete and partial segregation of group i axon terminals relative to the limits of the blobs of v1 were found. the results are compatible with recent evidence of incomplete segregation of visual information flow in v1 of old and new world primates
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.
Horizontal projections of area 17 in Cebus monkeys: metric features, and modular and laminar distribution
Amorim A.K.J.,Picano-Diniz C.W.
Brazilian Journal of Medical and Biological Research , 1997,
Abstract: Metric features and modular and laminar distributions of intrinsic projections of area 17 were studied in Cebus apella. Anterogradely and retrogradely labeled cell appendages were obtained using both saturated pellets and iontophoretic injections of biocytin into the operculum. Laminar and modular distributions of the labeled processes were analyzed using Nissl counterstaining, and/or cytochrome oxidase and/or NADPH-diaphorase histochemistry. We distinguished three labeled cell types: pyramidal, star pyramidal and stellate cells located in supragranular cortical layers (principally in layers IIIa, IIIb a, IIIb and IIIc). Three distinct axon terminal morphologies were found, i.e., Ia, Ib and II located in granular and supragranular layers. Both complete and partial segregation of group I axon terminals relative to the limits of the blobs of V1 were found. The results are compatible with recent evidence of incomplete segregation of visual information flow in V1 of Old and New World primates
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.
Adenosine A1 receptor-mediated inhibition of in vitro prolactin secretion from the rat anterior pituitary
Picano-Diniz, D.L.W.;Valen?a, M.M.;Antunes-Rodrigues, J.;
Brazilian Journal of Medical and Biological Research , 2006,
Abstract: in previous studies, we demonstrated biphasic purinergic effects on prolactin (prl) secretion stimulated by an adenosine a2 agonist. in the present study, we investigated the role of the activation of adenosine a1 receptors by (r)-n6-(2-phenylisopropyl)adenosine (r-pia) at the pituitary level in in vitro prl secretion. hemipituitaries (one per cuvette in five replicates) from adult male rats were incubated. administration of r-pia (0.001, 0.01, 0.1, 1, and 10 μm) induced a reduction of prl secretion into the medium in a u-shaped dose-response curve. the maximal reduction was obtained with 0.1 μm r-pia (mean ± sem, 36.01 ± 5.53 ng/mg tissue weight (t.w.)) treatment compared to control (264.56 ± 15.46 ng/mg t.w.). r-pia inhibition (0.01 μm = 141.97 ± 15.79 vs control = 244.77 ± 13.79 ng/mg t.w.) of prl release was blocked by 1 μm cyclopentyltheophylline, a specific a1 receptor antagonist (1 μm = 212.360 ± 26.560 ng/mg t.w.), whereas cyclopentyltheophylline alone (0.01, 0.1, 1 μm) had no effect. r-pia (0.001, 0.01, 0.1, 1 μm) produced inhibition of prl secretion stimulated by both phospholipase c (0.5 iu/ml; 977.44 ± 76.17 ng/mg t.w.) and dibutyryl camp (1 mm; 415.93 ± 37.66 ng/mg t.w.) with nadir established at the dose of 0.1 μm (225.55 ± 71.42 and 201.9 ± 19.08 ng/mg t.w., respectively). similarly, r-pia (0.01 μm) decreased (242.00 ± 24.00 ng/mg t.w.) the prl secretion stimulated by cholera toxin (0.5 mg/ml; 1050.00 ± 70.00 ng/mg t.w.). in contrast, r-pia had no effect (468.00 ± 34.00 ng/mg t.w.) on prl secretion stimulation by pertussis toxin (0.5 mg/ml; 430.00 ± 26.00 ng/mg t.w.). these results suggest that inhibition of prl secretion after a1 receptor activation by r-pia is mediated by a gi protein-dependent mechanism.
Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat
Picano-Diniz, D.L.W.;Valen?a, M.M.;Favaretto, A.L.V.;Antunes-Rodrigues, J.;
Brazilian Journal of Medical and Biological Research , 2002, DOI: 10.1590/S0100-879X2002000700015
Abstract: we investigated the effects of adenosine on prolactin (prl) secretion from rat anterior pituitaries incubated in vitro. the administration of 5-n-methylcarboxamidoadenosine (meca), an analog agonist that preferentially activates a2 receptors, induced a dose-dependent (1 nm to 1 μm) increase in the levels of prl released, an effect abolished by 1,3-dipropyl-7-methylxanthine, an antagonist of a2 adenosine receptors. in addition, the basal levels of prl secretion were decreased by the blockade of cyclooxygenase or lipoxygenase pathways, with indomethacin and nordihydroguaiaretic acid (ndga), respectively. the stimulatory effects of meca on prl secretion persisted even after the addition of indomethacin, but not of ndga, to the medium. meca was unable to stimulate prl secretion in the presence of dopamine, the strongest inhibitor of prl release that works by inducing a decrease in adenylyl cyclase activity. furthermore, the addition of adenosine (10 nm) mimicked the effects of meca on prl secretion, an effect that persisted regardless of the presence of licl (5 mm). the basal secretion of prl was significatively reduced by licl, and restored by the concomitant addition of both licl and myo-inositol. these results indicate that prl secretion is under a multifactorial regulatory mechanism, with the participation of different enzymes, including adenylyl cyclase, inositol-1-phosphatase, cyclooxygenase, and lipoxygenase. however, the increase in prl secretion observed in the lactotroph in response to a2 adenosine receptor activation probably was mediated by mechanisms involving regulation of adenylyl cyclase, independent of membrane phosphoinositide synthesis or cyclooxygenase activity and partially dependent on lipoxygenase arachidonic acid-derived substances.
Methylmercury intoxication and histochemical demonstration of NADPH-diaphorase activity in the striate cortex of adult cats
Oliveira, R.B.;Gomes-Leal, W.;do-Nascimento, J.L.M.;Picano-Diniz, C.W.;
Brazilian Journal of Medical and Biological Research , 1998, DOI: 10.1590/S0100-879X1998000900009
Abstract: the effects of methylmercury (mehg) on histochemical demonstration of the nadph-diaphorase (nadph-d) activity in the striate cortex were studied in 4 adult cats. two animals were used as control. the contaminated animals received 50 ml milk containing 0.42 μg mehg and 100 g fish containing 0.03 μg mehg daily for 2 months. the level of mehg in area 17 of intoxicated animals was 3.2 μg/g wet weight brain tissue. two cats were perfused 24 h after the last dose (group 1) and the other animals were perfused 6 months later (group 2). after microtomy, sections were processed for nadphd histochemistry procedures using the malic enzyme method. dendritic branch counts were performed from camera lucida drawings for control and intoxicated animals (n = 80). average, standard deviation and student t-test were calculated for each data group. the concentrations of mercury (hg) in milk, fish and brain tissue were measured by acid digestion of samples, followed by reduction of total hg in the digested sample to metallic hg using stannous chloride followed by atomic fluorescence analysis. only group 2 revealed a reduction of the neuropil enzyme activity and morphometric analysis showed a reduction in dendritic field area and in the number of distal dendrite branches of the nadphd neurons in the white matter (p<0.05). these results suggest that nadphd neurons in the white matter are more vulnerable to the long-term effects of mehg than nadphd neurons in the gray matter.
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