Single actomyosin motor interactions in skeletal muscle.

We present a study of intramuscular motion during contraction of skeletal muscle myofibrils. Myofibrillar actin was labeled with fluorescent dye so that the ratio of fluorescently labeled to unlabeled protein was 1:10(5). Such sparse labeling assured that there was on average only one actin-marker present in the focus at a given time. From the intensity signal in the two orthogonal detection channels, significant fluctuations, similar to fluorescent burst in diffusion-based single-molecule detection schemes, were identified via a threshold algorithm and analyzed with respect to their intensity and polarization. When only rigor complexes were formed, the fluctuations of polarized intensity were characterized by unimodal Gaussian photon distributions. During contraction, in contrast, bimodal Gaussian photon distributions were observed above the rigor background threshold. This suggests that the bimodal Gaussian photon distributions represent pre- and post-power stroke conformations. Clusters of polarized photons indicated an anisotropy decay of single actomyosin motors of ~9s during muscle contraction. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Remissao de processo expansivo intracerebral atribuivel a toxoplasmose cerebral na sindrome da imunodeficiencia adquirida(AIDS): relato de caso / Remission of an intracerebral expansive process atributable to cerebral toxoplasmosis in acquired immunodeficiency syndrome(AIDS): case report

Um paciente masculino de 32 anos, com Sindrome da Imunodeficiencia Adquirida (SIDA), apresentou sinais neurologicos focais a direita, nistagmo e disfasia, Tomografia Computadorizada (TC) cerebral mostrou processo expansivo intracerebral a esquerda. Foi instituido tratamento empirico para toxoplasmose cerebral com Pirimetamina e Sulfadiazina com regressao dos sinais neurologicos. A TC cerebral de controle apos seis semanas foi normal. E recomendado tratamento empirico para toxoplasmose cerebral em paciente com SIDA e processo expansivo intracerebral sem evidencia de outra patologia