[Effects of contrast, eccentricity and position in the detection of visual stimuli in humans]. / Efectos del contraste, excentricidad y posicion en la deteccion de estimulos visuales en humanos.

INTRODUCTION: Contrast, eccentricity and position of stimuli used on research of attention in human vision strongly vary among studies. AIM. To study how contrast, eccentricity and position affects detection of stimuli in humans. SUBJECTS AND METHODS: In adults with normal vision, we measured response times to stimuli (gray circles of 0.5 masculine of diameter) presented at random at eight polar coordinates, in three eccentricities with respect of fixation point (2.15, 3.83 and 5.53 masculine) and with three levels of contrast (6, 16 and 78%). RESULTS: Stimuli with eccentricity of 5.38 masculine and 6% of contrast showed the longest response times. In all eccentricities studied, longer response times were found with stimuli of 6% of contrast. Response times of stimuli of 16% and 78% of contrast showed similar response times in all eccentricities studied. Response times founded at eight polar coordinates were heterogeneous at eccentricities of 2.15 and 5.53 masculine, but not at 3.83 masculine. CONCLUSIONS: Contrast is the factor that most influence detection of visual stimuli used in this study, particularly at the biggest eccentricity employed. Response times among polar coordinates are also affected by eccentricities of 2.15 and 5.53 masculine, suggesting that distance of stimuli to fixation point is critical for visual detection of stimuli.

Efectos del contraste, excentricidad y posición en la detección de estímulos visuales en humanos / Effects of contrast, eccentricity and position in the detection of visual stimuli in humans

Introducción. Los estudios en humanos sobre percepción visual espacial tienen en común proyectar estímulos en laretina central, pero difieren notablemente en cuanto a su contraste, excentricidad y posición en el campo visual. Objetivo. Estudiar los efectos del contraste, excentricidad y posición en la detección de estímulos visuales presentados en la retina central humana. Sujetos y métodos. Se estudiaron los tiempos de respuesta, en personas con visión normal, a la presentación de estímulos (círculos grises de 0,5º de diámetro) presentados al azar en ocho coordenadas polares, con tres excentricidades (2,15,3,83 y 5,53º) y tres niveles de contraste (6, 16 y 78%). Resultados. Los estímulos presentados a 5,53º de excentricidad y contraste del 6% mostraron los tiempos de respuesta más elevados. Con este contraste, los tiempos de respuesta fueron mayores en todaslas excentricidades estudiadas. Por el contrario, con contrastes del 16 y 78%, los tiempos de respuesta fueron similares en las tres excentricidades. Para las ocho coordenadas polares, los tiempos de respuesta fueron homogéneos en la excentricidad de 3,83º y mostraron mayor variabilidad en las excentricidades de 2,15 y 5,53º. Conclusiones. De los tres factores analizados,el contraste es determinante en la detección de estímulos, especialmente en la excentricidad mayor. La posición también influye cuando los estímulos se presentan con excentricidades pequeñas o grandes, lo que sugiere que la distancia de los estímulos respecto al punto de fijación es crítica en la detección visual en este tipo de estudios

Introduction. Contrast, eccentricity and position of stimuli used on research of attention in human vision strongly vary among studies. Aim. To study how contrast, eccentricity and position affects detection of stimuli in humans. Subjects and methods. In adults with normal vision, we measured response times to stimuli (gray circles of 0.5º of diameter) presented at random at eight polar coordinates, in three eccentricities with respect of fixation point (2.15, 3.83 and 5.53º) and with three levels of contrast (6, 16 and 78%). Results. Stimuli with eccentricity of 5.38º and 6% of contrast showed the longest response times. In all eccentricities studied, longer response times were found with stimuli of 6% of contrast. Response times of stimuliof 16% and 78% of contrast showed similar response times in all eccentricities studied. Response times founded at eight polar coordinates were heterogeneous at eccentricities of 2.15 and 5.53º, but not at 3.83º. Conclusions. Contrast is the factor thatmost influence detection of visual stimuli used in this study, particularly at the biggest eccentricity employed. Response times among polar coordinates are also affected by eccentricities of 2.15 and 5.53º, suggesting that distance of stimuli to fixationpoint is critical for visual detection of stimuli

Rituximab in the treatment of dermatomyositis and other inflammatory myopathies. A report of 4 cases and review of the literature.

OBJECTIVE: Rituximab is an anti-CD20 monoclonal antibody targeting B cells, which has been used with success in a wide variety of autoimmune diseases. The experience with this drug in patients with inflammatory myopathies (IM), nonetheless, is still limited. We review the literature and highlight several aspects in relation to therapy with rituximab in IM. METHODS: We performed a research in the MEDLINE DATABASE. All cases identified from the literature research and cases diagnosed in our Unit were included in the analysis. RESULTS: We identified 49 patients with IM treated with rituximab in the review of the literature carried out (31 female; 18 male), including our patients. Dermatomyositis (DM) was the most common disorder for which rituximab treatment was administered (69.4%). The other diseases treated included polymyositis (PM) 16.3%, antisynthetase syndrome (AS) 8.2%, one case with anti-SRP-syndrome and other with juvenile dermatomyositis. The median time to diagnosis was 48 (0.75-480) months. Sixty-five per cent (65.3%) of patients presented with skin manifestations, 89.8% with muscle weakness, 7.3% with arthritis, 16.3% with interstitial lung disease, and 7.3% with cardiomyopathy. Seventy-one (71.4%) of the patients received only one course of rituximab, 18.4% two courses, 4.1% three, 2% four and only 4.1% five. We have observed both among our patients and those reported in the literature a high rate of response to rituximab, 75% of our patients and 72.5% of those described in the literature showed a good response. The median time free of symptoms between two courses was 12 (6-19) months. Rituximab was generally well tolerated by all patients, with no serious adverse events. Most of the adverse events reported were mainly infections, particularly respiratory tract infections. CONCLUSIONS: It is our belief that rituximab may be an optimal therapeutic choice for inflammatory myopathies. Nevertheless, there is a need for additional studies in order to assess the optimal regimen of treatment in the different subsets, as well as the initial dose, combination of treatments and re-treatment schedule.

Descargas repetitivas complejas en una miopatía mitocondrial / Complex repetitive discharges in a mitochondrial myopathy

Mujer de 54 años de edad estudiada por debilidad crónica, atrofia muscular y elevación de creatin Kinshasa en sangre. El EMG de musculatura proximal de miembros superiores e inferiores reveló se registraron numerosas descargas repetitivas de potenciales de unidad motora polifásicos con amplitudes y frecuencias de disparo constantes, estaban integradas por 6 potenciales de fibra simple con un “jitter” entre sus diferentes componentes inferior a 5 µseg. Que sepamos, no han sido descritas descargas repetitivas complejas de estas características en miopatías mitocondriales del hombre, aunque si han sido referidas en el perro

A 54 year old woman was studied in our lab because chronic weakness, limb-girdle muscular atrophy and increased blood CK level. Electromyography assessment of proximal muscles in arms and legs revealed complex repetitive discharges with a very low interpotential jitter lesser than 5 µseg, further indicating the absence of end plate activity in their causation. Then, they are thought to originate form spontaneous activity in a single muscle fiber which activates one or more adjacent muscle fibre ephaptically. Ephaptic transmission from fibre to fibre in skeletal muscle is ordinarily prevented by the absence of adjacent simultaneously depolarizing muscle fibres, because of the pseudorandom nature of the distribution of the motor unit. When this relation is disturbed by reorganization of the motor unit in neurogenic and, to a lesser extent, in cronic myopathic diseases, cross-firing of adjacent muscle fibres is more likely. In our knowledge, this is the first time that complex repetitive discharges have been found in a human mitochondrial myopathic although they have been yet reported in sheepdog littermates

XIV Reunión Anual de la Asociación Ibérica de Patología del Sueño. El binomio dolor-sueño en enfermedades inflamatorias autoinmunes / No disponible

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