1,721,402 research outputs found
Clinical and neuroradiological findings of Moyamoya Disease in Italy.
No full textI.F.: 0.954, CLINICAL NEUROLOGY, SURGER
Aspetti clinici e neuroradiologici nella malattia di moya moya: studio casistico italiano su 34 casi
No full textSampling variance and distribution of the D' measure of overall gametic disequilibrium between multiallelic loci
No full textThe development of the theory of estimation of gametic disequilibrium for multiallelic systems is particularly necessary, since a large number of the genetic markers available at present are highly polymorphic multiallelic systems. The D' coefficient is one of the most commonly used measures of the extent of overall disequilibrium between all possible pairs of alleles at two multiallelic loci. Nevertheless, the sampling properties of this measure of overall disequilibrium, are to date, unknown. In this work, we have derived explicit expressions by large-sample theory to compute the approximate sampling variance of D^' between pairs of multiallelic loci, when samples of haplotypes are taken from populations. Formulae for calculating the asymptotic sampling variance were checked by Monte Carlo simulation. In addition, the magnitude of the sampling variance of D^' was investigated under different scenarios of disequilibrium between multiallelic loci. Extensive simulations were also carried out for describing the sampling distribution of D^', conditioned on the sample size, number of alleles and their frequencies, and disequilibrium components. It was found that the sampling distribution of D^' generally approaches well the theoretical normal distribution for experimental sample sizes, particularly when loci have many alleles. Disequilibrium data between microsatellite loci of human chromosome 11p are used for illustration. These investigations increase substantially our knowledge about this widely used measure of overall disequilibrium, which is relevant to evaluate disequilibrium between multiallelic loci in populations
Neurofibromatosis type 1 and type I Chiari malformation: an inusual association.
No full textAbstract We report an 11-year-old boy with neurofibromatosis type 1 (NF1) and asymptomatic type I Chiari malformation. This association may be considered a pure coincidence, due to the relative frequency of the two conditions, but recent reports describing the same association suggest that type I Chiari malformation probably should be added to the list of abnormalities of the central nervous system reported in patients affected by NF1
Conventional and diffusion-weighted MRI in progressive multifocal leukoencephalopathy: new elements for identification and follow-up.
No full textSpinal cord and cauda equina MRI findings in metachromatic leukodystrophy: case report
No full textMetachromatic leukodystrophy (MLD) is an autosomal recessive disease with well-documented intracranial findings on neuroimaging both by computed tomography (CT) and MRI. We describe the first case of late infantile MLD with spinal involvement revealed by MRI as marked contrast enhancement of nerve roots at the level of the cauda equina
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Vertebral and spinal cavernous angiomas associated with familial cerebral cavernous malformation.
No full textOptic atrophy as the first symptom in Hallervorden-Spatz Syndrome
Full text linkAbstract
A 16-year-old boy with the classic or postinfantile type of Hallervorden-Spatz syndrome is described. Bilateral optic atrophy with visual loss but without retinal changes was the only presenting symptom. Mild cognitive impairment, behavioural disturbances and insidious extrapyramidal involvement appeared later. MRI showed marked symmetrical hypointensity of the globi pallidi and substantia nigra. This new observation suggests that the occurrence of optic atrophy in a patient with Hallervorden-Spatz syndrome should be regarded as noncoincidental and stresses the importance of an accurate neurological work-up in all adolescents with any unusual form of progressive optic atrophy
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