221 research outputs found

    Nuevos métodos de tintura en frio para lana.

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    Este trabajo se inició como un estudio de la influencia de la urea en el proceso de tintura. Se investigaron los efectos de la urea sobre fibras y colorantes, teniendo presente sus dos posibles factores. 1. Las soluciones de urea hinchan la lana permitiendo el fácil acceso del colorante. 2. La urea dispersa y disgrega el colorante permitiendo un acceso más facil de las especies monomoleculares.Peer Reviewe

    Evidence for Cortical Functional Changes in Patients With Migraine and White Matter Abnormalities on Conventional and Diffusion Tensor Magnetic Resonance Imaging

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    Background— In this study, we used functional MRI (fMRI) to investigate the pattern of cortical activations after a simple motor task in patients with migraine and white matter (WM) abnormalities on conventional MRI scans of the brain. We also investigated whether the extent of brain activations was correlated with WM structural pathology measured using diffusion tensor (DT) MRI. Methods— From 15 right-handed patients with migraine and 15 sex- and age-matched, right-handed healthy volunteers, we obtained the following: (1) fMRI (repetitive flexion-extension of the last 4 fingers of the right hand), (2) dual-echo turbo spin echo scans, and (3) pulsed-gradient spin-echo echo-planar sequence to calculate DT-MRI maps. fMRI analysis was performed using SPM99 and cluster detection. We measured the volume, the average mean diffusivity ( ), and the average fractional anisotropy of all lesions seen on the dual-echo scans. histograms of the normal-appearing WM were also produced. Results— Compared with healthy volunteers, migraine patients had a larger relative activation of the contralateral primary sensorimotor cortex ( P =0.01) and a rostral displacement of the supplementary motor area ( P =0.03). The shapes of the curves reflecting the time course for fMRI signal intensity changes were similar between migraine patients and controls for all of the cortical areas we studied. Compared with healthy subjects, migraine patients had significantly lower histogram peak height of the normal-appearing WM histogram ( P =0.02), which was found to be correlated with the extent of displacement of the supplementary motor area ( r =−0.80, P <0.001). Conclusions— This study suggests that functional cortical changes occur in patients with migraine and brain MRI abnormalities and that they might be secondary to the extent of subcortical structural damage

    Brain Gray Matter Changes in Migraine Patients With T2-Visible Lesions

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    Background and Purpose— In migraine patients, functional imaging studies have shown changes in several brain gray matter (GM) regions. However, 1.5-T MRI has failed to detect any structural abnormality of these regions. We used a 3-T MRI scanner and voxel-based morphometry (VBM) to assess whether GM density abnormalities can be seen in patients with migraine with T2-visible abnormalities and to grade their extent. Methods— In 16 migraine patients with T2-visible abnormalities and 15 matched controls, we acquired a T2-weighted and a high-resolution T1-weighted sequence. Lesion loads were measured on T2-weighted images. An optimized version of VBM analysis was used to assess regional differences in GM densities on T1-weighted scans of patients versus controls. Statistical parametric maps were thresholded at P <0.001, uncorrected for multiple comparisons. Results— Compared with controls, migraine patients had areas of reduced GM density, mainly located in the frontal and temporal lobes. Conversely, patients showed increased periacqueductal GM (PAG) density. Compared with patients without aura, migraine patients with aura had increased density of the PAG and of the dorsolateral pons. In migraine patients, reduced GM density was strongly related to age, disease duration, and T2-visible lesion load ( r ranging from −0.84 to −0.73). Conclusions— Structural GM abnormalities can be detected in migraine patients with brain T2-visible lesions using VBM and a high-field MRI scanner. Such GM changes comprise areas with reduced and increased density and are likely related to the pathological substrates associated with this disease
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