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| Barboni,M.T.S.; Gomes,B.D.; Souza,G.S.; Rodrigues,A.R.; Ventura,D.F.; Silveira,L.C.L.. |
| The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Contrast sensitivity; Color vision; Steady-state visual evoked cortical potential; Visual thresholds; Spatial vision; Psychophysics. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2013000200154 |
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| Tanan,C.L.; Ventura,D.F.; de Souza,J.M.; Grotzner,S.R.; Mela,M.; Gouveia Jr.,A.; Oliveira-Ribeiro,C.A.. |
| Methyl mercury (MeHg) is highly neurotoxic, affecting visual function in addition to other central nervous system functions. The effect of mercury intoxication on the amplitude of horizontal cell responses to light was studied in the retina of the fish Hoplias malabaricus. Intracellular responses were recorded from horizontal cells of fish previously intoxicated with MeHg by intraperitoneal injection (IP group) or by trophic exposure (T group). Only one retina per fish was used. The doses of MeHg chloride administered to the IP group were 0.01, 0.05, 0.1, 1.0, 2.0, and 6.0 mg/kg. The amplitudes of the horizontal cell responses were lower than control in individuals exposed to 0.01 (N = 4 retinas), 0.05 (N = 2 retinas) and 0.1 mg/kg (N = 1 retina), whereas... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Methyl mercury; Horizontal cells; Electrophysiology; Hoplias malabaricus; Retina. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006000700017 |
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| Rodrigues,A.R.; Souza,C.R.B.; Braga,A.M.; Rodrigues,P.S.S.; Silveira,A.T.; Damin,E.T.B.; Côrtes,M.I.T.; Castro,A.J.O.; Mello,G.A.; Vieira,J.L.F.; Pinheiro,M.C.N.; Ventura,D.F.; Silveira,L.C.L.. |
| We measured visual performance in achromatic and chromatic spatial tasks of mercury-exposed subjects and compared the results with norms obtained from healthy individuals of similar age. Data were obtained for a group of 28 mercury-exposed subjects, comprising 20 Amazonian gold miners, 2 inhabitants of Amazonian riverside communities, and 6 laboratory technicians, who asked for medical care. Statistical norms were generated by testing healthy control subjects divided into three age groups. The performance of a substantial proportion of the mercury-exposed subjects was below the norms in all of these tasks. Eleven of 20 subjects (55%) performed below the norms in the achromatic contrast sensitivity task. The mercury-exposed subjects also had lower red-green... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mercury exposure; Mercury toxicity; Contrast sensitivity; Color vision; Visual dysfunction; Amazon riverside communities. |
| Ano: 2007 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007000300018 |
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| Zachi,E.C.; Ventura,D.F.; Faria,M.A.M.; Taub,A.. |
| We assessed the neuropsychological test performances of 26 patients (mean age = 41.5 ± 6.1 years; mean years of education = 9.8 ± 1.8; 20 males) diagnosed with chronic occupational mercurialism who were former workers at a fluorescent lamp factory. They had been exposed to elemental mercury for an average of 10.2 ± 3.8 years and had been away from this work for 6 ± 4.7 years. Mean urinary mercury concentrations 1 year after cessation of work were 1.8 ± 0.9 µg/g creatinine. Twenty control subjects matched for age, gender, and education (18 males) were used for comparison. Neuropsychological assessment included attention, inhibitory control, verbal and visual memory, verbal fluency, manual dexterity, visual-spatial function, executive function, and semantic... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mercury; Occupational exposure Cognitive assessment Neuropsychological dysfunction Neuropsychological tests. |
| Ano: 2007 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007000300019 |
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| Bonci,D.M.O.; Lima,S.M.A. de; Grötzner,S.R.; Oliveira Ribeiro,C.A.; Hamassaki,D.E.; Ventura,D.F.. |
| To quantify the effects of methylmercury (MeHg) on amacrine and on ON-bipolar cells in the retina, experiments were performed in MeHg-exposed groups of adult trahiras (Hoplias malabaricus) at two dose levels (2 and 6 µg/g, ip). The retinas of test and control groups were processed by mouse anti-parvalbumin and rabbit anti-alphaprotein kinase C (alphaPKC) immunocytochemistry. Morphology and soma location in the inner nuclear layer were used to identify immunoreactive parvalbumin (PV-IR) and alphaPKC (alphaPKC-IR) in wholemount preparations. Cell density, topography and isodensity maps were estimated using confocal images. PV-IR was detected in amacrine cells in the inner nuclear layer and in displaced amacrine cells from the ganglion cell layer, and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Methylmercury; Retina; Hoplias malabaricus; Amacrine cells; Displaced amacrine cells; ON-bipolar cells. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2006000300011 |
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