Search results for "HETEROGENEITY"
showing 10 items of 402 documents
Molecular Analysis of the Supramolecular Usher Protein Complex in the Retina
2007
Human Usher syndrome (USH) is the most common form of deaf-blindness and also the most frequent case of recessive retinitis pigmentosa. According to the degree of the clinical symptoms, three different types of the Usher syndrome are distinguished: USH1, USH2 and USH3 (Davenport and Omenn, 1977). USH is genetically heterogeneous with eleven chromosomal loci, which can be assigned to the three USH types (USH1A-G, USH2A-C, USH3A) (Petit, 2001). Out of these, USH1 is the most severe form, characterized by profound congenital deafness, constant vestibular dysfunction and prepubertal-onset retinitis pigmentosa. USH2 patients show a milder congenital deafness, a slightly later onset of retinitis …
Estudio genético molecular del síndrome de Usher en España
2005
Usher syndrome (USH) associates deafness and retinitis pigmentosa (RP). It is a disease both clinically and genetically heterogeneous. It is inherited as an autosomal recessive trait and its prevalence makes it the most frequent association of hearing loss and RP. Clinically Usher syndrome is divided into type I (USH1), II (USH2) and III (USH3), according to the severity of hearing loss, age of onset of RP and the existence or not of vestibular dysfunction. There are at least 7 different localizations for USH1 and 5 genes have been identified. For USH2, 3 loci and 2 genes have been reported and USH3 is due to Clarin-1 gene. Our aim is to perform a clinical and genetic characterization of al…
Heterogeneity of HVR-1 quasispecies is predictive of early but not sustained virological response in genotype 1b-infected patients undergoing combine…
2003
ISDR mutation pattern and HVR-1 quasispecies were analyzed in HCV genotype 1b-infected patients treated with either PEG- or STD-IFN plus ribavirin, in order to find virological correlates of therapy outcome. ISDR region analysis, performed at baseline (T0) and at 4 weeks of therapy (T1), indicated that ISDR mutation pattern was not predictive of response to treatment. Moreover, no selection of putative resistant strains in the first month of therapy was observed. Viral load was not correlated with any parameter of HVR-1 heterogeneity. Among the HVR-1 heterogeneity parameters considered, complexity was inversely correlated to viral load decline at T1. In univariate analysis, complexity, prop…
Evidence of Recombination in Intrapatient Populations of Hepatitis C Virus.
2008
Hepatitis C virus (HCV) is a major cause of liver disease worldwide and a potential cause of substantial morbidity and mortality in the future. HCV is characterized by a high level of genetic heterogeneity. Although homologous recombination has been demonstrated in many members of the family Flaviviridae, to which HCV belongs, there are only a few studies reporting recombination on natural populations of HCV, suggesting that these events are rare in vivo. Furthermore, these few studies have focused on recombination between different HCV genotypes/subtypes but there are no reports on the extent of intra-genotype or intra-subtype recombination between viral strains infecting the same patient.…
Informational analysis of forest landscape spatial heterogeneity
1999
Summary Under the perspective of forest ecosystem management, landscape is interpreted as a functioning structure. From an inventory and monitoring operational point of view, such an approach implies wise use of geographic information systems and remote sensing techniques enabling a global view of the territorial mosaic. From a methodological point of view, landscape ecology theory may be used as the assessment framework. Remotely sensed data provide excellent opportunities for the involved analyses, using both vegetation density measures and spatial statistics. The objective of this paper was to assess landscape spatial heterogeneity using an analysis method based on Shannon's information …
The spatial dimension of the French private rental markets: Evidence from microgeographic data in 2015
2021
International audience; This article draws on data collected by local rental observatories in 12 French urban units in 2015 to analyze the spatial dimension of hedonic rental prices in the private rental market through (i) the spatial heterogeneity between urban units and (ii) the wide variety of contextual and locational characteristics (socio-economic, environmental (dis)amenity, and accessibility) and flexible specifications to capture their potential non-linear influence on rent. Based on a joint test of equality of coefficients across all urban units, we find that hedonic prices differ for 75% of the characteristics, thereby justifying a detailed analysis of heterogeneity. Lyon, Nice, …
Exploratory spatial data analysis of the distribution of regional per capita GDP in Europe, 1980-1995
2000
The aim of this paper is to study the dynamics of European regional per capita product over time and space. This purpose is achieved by using the recently developed methods of Exploratory Spatial Data Analysis. Using a sample of European regions over the 1980-1995 period, we find strong evidence of global and local spatial autocorrelation in per capita GDP throughout the period. The detection of clusters of high and low per capita products during the period is an indication of the persistence of spatial disparities between European regions. This analysis is finally refined by the investigation of the spatial pattern of regional growth. Key words:exploratory spatial data analysis; distributi…
The influence of geography on the spatial agglomeration of production in the European Union
2012
Abstract We investigate the relative impact of geographic features on the location of production in the European Union. Specifically, we attempt to quantify how much of the spatial pattern of GDP can be attributed to exogenous first-nature elements alone and how much can be derived from endogenous second-nature factors. In order to disentangle both effects empirically, we control for second-nature factors. A method based on the decomposition of the per capita GDP variance is applied to a panel of 1,171 European NUTS 3 regions for 2006. We demonstrate that variable and model misspecifications may bias results unless proper allowance is made for spatial autocorrelation and spatial heterogenei…
Assessment of inputs to land surface processes models derived from hyperspectral multiangular data
2002
Global Models of the Earth - Atmosphere System describe the role of the terrestrial biosphere using increasingly complex Land Surface Models (LSM). These models mimic the exchange of energy, water and carbon between the land and the atmosphere, with emphasis on the role of terrestrial vegetation. Literature shows a clear trend towards fully interactive LSM-s, i.e. accounting for the dynamic response of vegetation to weather and climate. The latter may not be limited to biomass accumulation and address slower changes in vegetation type and composition. Improving the performance of such models require addressing two broad questions: Can we measure vegetation properties with the accuracy requi…
Biomarkes of aging
2009
Ageing is a complex process that negatively impacts the development of the different systems and its ability to function. On the other hand, the rate of ageing in humans is not uniform, due to genetic heterogeneity and the influence of environmental factors. Thus, the ageing rate, measured as the decline of functional capacity and stress resistance, seems to be different in every individual. Therefore, attempts have been made to analyse this individual age, the so-called biological age, in comparison to chronological age. Age-related changes in body function or composition that could serve as a measure of biological age and predict the onset of age-related diseases and/or residual lifetime …