Análise da sensibilidade ao contraste em militares aeronavegantes: Estudo exploratório / Analysis of contrast sensitivity in military aircrew: Exploratory study

A visão é considerada o sentido mais importante para obter informações e referências durante o voo, sendo responsável por cerca de 80% da orientação no ambiente de aviação. A acuidade visual (AV) é a função visual mais importante testada nos aeronavegantes (indivíduos cuja função laboral se desenvolve dentro de uma aeronave). A sensibilidade ao contraste (SC) é outra importante função visual, definida como a capacidade de discernir uma imagem entre luminâncias de diferentes níveis. Os testes de SC propiciam uma melhor descrição das propriedades resolutivas do sistema visual em relação às obtidas apenas com a medida da AV. Por esta razão este estudo objetivou caracterizar a SC em uma amostra de militares aeronavegantes e compará-la com os resultados de um grupo controle (militares não aeronavegantes). Para tal, foram constituídos dois grupos, pelo critério de acessibilidade, a saber: aeronavegantes (AE; n=58; 34,5 ± 5,77 anos) e grupo controle (GC; n=28; 35,14 ± 7,2 anos), todos do serviço ativo e do sexo masculino, totalizando 172 olhos. Os dados foram coletados no momento da inspeção de saúde dos militares. Primeiramente, foi realizado o exame oftalmológico conforme as instruções técnicas em vigor e, na sequência, o teste de SC, utilizando a Tabela de Pelli-Robson. Além disso, foi preenchido um questionário para obtenção de informações pessoais. Foi realizada a estatística descritiva, a distribuição de frequências e a relação entre variáveis qualitativas (teste qui-quadrado), considerando p ≤ 0,05. A  pesquisa foi aprovada pelo Comitê de Ética em Pesquisa do Hospital de Força Aérea do Galeão (Número de Registro 3.476.886). A SC média encontrada no grupo de AE foi de 1,71 log SC em olho direito (OD); 1,71 log SC em olho esquerdo (OE) e 1,97 log SC em ambos os olhos (AO). A SC média encontrada no GC foi de 1,69 log SC em OD; 1,66 log SC em OE e 1,96 log SC em AO. Houve diferença estatisticamente significativa entre os grupos para a SC do OE. A SC do grupo AE foi, em média, maior que a do GC. Os valores de referência da Tabela de Pelli-Robson encontrados na literatura para a faixa etária estudada foram de 1,80 log SC e 1,95 log SC para medidas monoculares e binoculares, respectivamente.  Em ambos os grupos, a média dos resultados da SC monocular ficou ligeiramente abaixo do valor de referência e a da SC binocular ficou acima desse valor. Para fins periciais, a inclusão do teste de SC proporcionaria um exame oftalmológico mais completo, permitindo a detecção mais precoce de determinadas patologias oculares e de possíveis alterações na SC relacionadas à realização de cirurgia refrativa. A avaliação dessa função visual possibilitaria também reconhecer aspectos relativos à performance visual, contribuindo para a otimização do desempenho humano operacional. Sugere-se estudos posteriores a fim de verificar e categorizar a SC em quadros/especialidades específicas para militares.

Examination of age-dependent effects of fetal ethanol exposure on behavior, hippocampal cell counts, and doublecortin immunoreactivity in rats

WOS: 000333998100002PubMed ID: 24302592Ethanol is known as a potent teratogen having adverse effects on brain and behavior. However, some of the behavioral deficits caused by fetal alcohol exposure and well expressed in juveniles ameliorate with maturation may suggest some kind of functional recovery occurring during postnatal development. The aim of this study was to reexamine age-dependent behavioral impairments in fetal-alcohol rats and to investigate the changes in neurogenesis and gross morphology of the hippocampus during a protracted postnatal period searching for developmental deficits and/or delays that would correlate with behavioral impairments in juveniles and for potential compensatory processes responsible for their amelioration in adults. Ethanol was delivered to the pregnant dams by intragastric intubation throughout 7-21 gestation days at daily dose of 6 g/kg. Isocaloric intubation and intact control groups were included. Locomotor activity, anxiety, and spatial learning tasks were applied to juvenile and young-adult rats from all groups. Unbiased stereological estimates of hippocampal volumes, the total number of pyramidal and granular cells, and double cortin expressing neurons were carried out for postnatal days (PDs) PD1, PD10, PD30, and PD60. Alcohol insult during second trimester equivalent caused significant deficits in the spatial learning in juvenile rats; however, its effect on hippocampal morphology was limited to a marginally lower number of granular cells in dentate gyrus (DG) on PD30. Thus, initial behavioral deficits and the following functional recovery in fetal-alcohol subjects may be due to more subtle plastic changes within the hippocampal formation but also in other structures of the extended hippocampal circuit. Further investigation is required. (c) 2013 Wiley Periodicals, Inc. Develop Neurobiol 74: 498-513, 2014METU Scientific Research Fund; Turkish Scientific and Technical Council (TUBITAK) [SBAG-107S069]; TUBITAK PhD scholarshipTurkish Scientific and Technical Council (TUBITAK) [SBAG-107S069]Contract grant sponsor: METU Scientific Research Fund.; Contract grant sponsor: Turkish Scientific and Technical Council (TUBITAK); contract grant number: SBAG-107S069 (to E.J.D.).; Contract grant sponsor: TUBITAK PhD scholarship (to B.E.C.)

Exame de paciente com doença neurológica Patient examination with neurologic disorders

A neurologia oftalmológica e otológica tem se desenvolvido nos últimos anos até constituir uma extensa disciplina especializada. Dispomos na atualidade de importantes manuais sobre a mesma, os quais têm, ante tudo, o caráter de obras de consulta; em troca, se faz sentir, sem dúvida, a necessidade de descrições compreendidas que destaquem o mais essencial e definitivamente adquirido da bibliografia, quase inabarcável, em relação aos domínios desta especialidade; assim, temos demonstrados os repetidos desejos de alunos, solicitando a publicação de nossas conferências para pós-graduados sobre esta matéria. Fizemos uma exposição resumida da neurologia com interesse neurooftalmológico para que os estudantes desta matéria possam se interessar sobre a mesma.Lately, the ophthalmologic and otological neurology has been developed into a broad and specialized subject. Currently, we have important manuals on this issue, which above all have the purpose of a work for research. However, undoubtedly one can feel the necessity for comprehended descriptions that will highlight what is most essential and definitely taken from the biography, almost inaccessible, regarding the realm of such specialty; thus, the repeated wishes of the students asking for the publication of our lectures for the post-graduates on this matter have been demonstrated. We have included a summary of the neurology with neuro-ophthalmologic interest aiming at drawing the students' attention on this subject

Brimonidine tartrate effect on retinal spreading depression depends on Müller cells

Objective: Demonstrate the Brimonidine effect over Retinal Spreading Depression (SD). Brimonidine is an alpha-2–adrenergic receptor agonist, used in the management of glaucoma. Alpha2-agonists have been shown to be neuroprotective in various experimental models, however the molecular and cellular targets leading to these actions are still poorly defined. The SD of neuronal electric activity is a wave of cellular massive sustained depolarization that damages the nervous tissue. Local trauma, pressure, ischemic injuries and other chemical agents as high extracellular potassium concentration or glutamate, can trigger SD, leading to exaggerated focal electrical followed by an electrical silence. Methods: Using chicken retina as model, we performed alpha2-receptor detection by Western Blotting and Immunohistochemistry. After that we obtained electrical signals of SD by microelectrodes on retina in the absence or presence of Brimonidine. For in vivo visualization we observed retina with optical coherence tomography on normal state, with SD passing, and with SD + Brimonidine. Results: Our data demonstrated that: (1) alpha2-adrenergic receptors are present in Müller cells, (2) the treatment with Brimonidine decreases the SD‘s velocity as well as the voltage of SD waves and (3) OCT revealed that SD creates a hyper reflectance at inner plexiform layer, but on retinal treatment with brimonidine, SD was not visualized. Conclusions: Our study about brimonidine possible pathways of neuroprotection we observed it reduces SD (a neuronal damage wave), identified a new cellular target – the Müller cells, as well as, firstly demonstrated SD on OCT, showing that the inner plexiform layer is the main optically affected layer on SD

Axonal electrovisiogram as an electrophysiological test to evaluate optic nerve and inner retina electrical potentials: findings in normal subjects

PURPOSES: To standardize and validate the technique of axonal electrovisiogram (AxEvg), defining its normative values and parameters and characterizing its findings in normal individuals. METHODS: We enrolled 140 normal individuals (280 eyes) divided into seven groups according to age, each one with 10 males and 10 females. The technique was based on monocular visual stimulation by a 0 dB intensity bright flash on Ganzfeld bowl at a presentation rate of 1.4 Hz. Golden cup electrodes were used and electrical waves were acquired after artifact rejection. For each amplitude and implicit time peak we calculated the mean, median, pattern deviation, minimum and maximum values and 95% confidence interval. RESULTS: Monocular visual stimulation with bright flash under mesopic conditions was the standard technical procedure established. The normal AxEvg waveform consists of an initial positive wave (named P1, with mean amplitude of 2.0 mV and mean implicit time peak of 23.1 ms) followed by a negative wave (named N1, with mean amplitude of -3.9 mV and mean implicit time peak of 41.4 ms). No significant differences were observed between males and females or between right and left eyes, but there was an increased P1 and N1 implicit time peaks according to age. Implicit time characteristics suggest that P1 wave represents an optic nerve electrical potential and N1 wave represents an inner retinal layers potential. CONCLUSIONS: AxEvg can be considered a pre-chiasmatic visual evoked potential capable to reliably record the electrical activity of optic nerve and inner retina. The findings suggest that AxEvg may be useful as an electrophysiological test in the diagnosis of neuroretinal diseases