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  • 1
    Keywords: RISK ; mechanisms ; ALZHEIMERS-DISEASE ; HUNTINGTONS-DISEASE ; human brain ; AGE-RELATED-CHANGES ; OLDER-ADULTS ; VOXEL-BASED MORPHOMETRY ; FRACTIONAL ANISOTROPY ; Longitudinal study ; Cortical connectivity ; HUMAN CORPUS-CALLOSUM ; TENSOR-BASED MORPHOMETRY ; WHITE-MATTER DAMAGE
    Abstract: Cross-sectional studies using diffusion tensor imaging (DTI) suggest decline of the integrity of intracortically projecting fiber tracts with aging and in neurodegenerative diseases, such as Alzheimer's disease (AD). Longitudinal studies on the change of fiber tract integrity in normal and pathological aging are still rare. Here, we prospectively studied 11 healthy elderly subjects and 14 subjects with amnestic mild cognitive impairment (MCI), a clinical risk group for AD, using high-resolution DTI and MRI at baseline and after 13 to 16 months follow-up. Fractional anisotropy (FA), a DTI measure of fiber tract integrity, was compared across time points and groups using a repeated measures linear model and tract based spatial statistics. Additionally, we determined rates of grey matter and white matter atrophy using automated deformation based morphometry. Healthy elderly subjects showed decline of FA in intracortical projecting fiber tracts, such as corpus callosum, superior longitudinal fasciculus, uncinate fasciculus, inferior fronto-occipital fasciculus, and cingulate bundle (p 〈 0.05, corrected for multiple comparisons). MCI subjects showed significant FA decline predominantly in the anterior corpus callosum (p 〈 0.05, corrected for multiple comparisons). Grey and white matter atrophy involved prefrontal, parietal, and temporal lobe areas in controls and prefrontal, cingulate, and parietal lobe areas in MCI subjects and agreed with the pattern of fiber tract changes. Our findings indicate that DTI allows detection of microstructural changes in subcortical fiber tracts over time that are related to aging as well as to early stages of AD type neurodegeneration. The underlying mechanisms for these changes are unknown.
    Type of Publication: Journal article published
    PubMed ID: 20847446
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  • 2
    Keywords: DIAGNOSIS ; imaging ; PATIENT ; TRIAL ; EXPERIENCE ; CONTRAST AGENTS ; GADOBENATE-DIMEGLUMINE ; NATURAL-HISTORY ; MULTIPLE-SCLEROSIS ; MR imaging ; review ; monitoring ; MS ; RECOMMENDATIONS ; DIAGNOSTIC-CRITERIA ; GLATIRAMER ACETATE ; NEPHROGENIC SYSTEMIC FIBROSIS ; 1ST DEMYELINATING EVENT ; CLINICALLY ISOLATED SYNDROMES ; DOSE GADOTERIDOL ; ENHANCING LESIONS
    Abstract: MR imaging is widely used for the diagnosis and monitoring of patients with MS. Applications and protocols for MR imaging continue to evolve, prompting a need for continual reassessments of the optimal use of this technique in clinical practice. This article provides updated recommendations on the use of MR imaging in MS, based on a review of the trial evidence and personal experiences shared at a recent expert meeting of radiologists and neurologists
    Type of Publication: Journal article published
    PubMed ID: 20019103
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  • 3
    Keywords: brain ; DISEASE ; MRI ; ALZHEIMERS-DISEASE ; SCHIZOPHRENIA ; REGION ; Alzheimer's disease ; multicenter studies ; HEALTHY-VOLUNTEERS ; HUNTINGTONS-DISEASE ; Diffusion Tensor Imaging ; DTI ; early diagnosis ; FRACTIONAL ANISOTROPY ; MEAN DIFFUSIVITY ; DIAGNOSTIC UTILITY ; Effect size estimation ; Physical phantom ; TRACT INTEGRITY
    Abstract: Diffusion tensor imaging (DTI) detects white matter damage in neuro-psychiatric disorders, but data on reliability of DTI measures across more than two scanners are still missing. In this study we assessed multicenter reproducibility of DTI acquisitions based on a physical phantom as well as brain scans across 16 scanners. In addition, we performed DTI scans in a group of 26 patients with clinically probable Alzheimer's disease (AD) and 12 healthy elderly controls at one single center. We determined the variability of fractional anisotropy (FA) measures using manually placed regions of interest as well as automated tract based spatial statistics and deformation based analysis. The coefficient of variation (CV) of FA was 6.9% for the physical phantom data. The mean CV across the multicenter brain scans was 14% for tract based statistics, and 29% for deformation based analysis. The degree of variation was higher in less organized fiber tracts. Our findings suggest that a clinical and physical phantom study involving more than two scanners is indispensable to detect potential sources of bias and to reliably estimate effect size in multicenter diagnostic trials using DTI.
    Type of Publication: Journal article published
    PubMed ID: 22078796
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Gene 102 (1991), S. 197-203 
    ISSN: 0378-1119
    Keywords: DNA methylation ; Recombinant DNA ; X chromosome ; human ; rodent ; sequence conservation
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0888-7543
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-5233
    Keywords: Visual evoked potentials ; Hyperglycaemic clamp ; Central nervous conduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Multimodality evoked potentials frequently reveal subclinical involvement of the central nervous system in patients with insulin-dependent diabetes mellitus. We devised this study to evaluate the possible effects of acute hyperglycaemia on visual evoked potential (VEP) parameters in type 1 diabetic patients. A hyperglycaemic clamp (250 mg/dl for 180 min) was performed in ten patients. Monocular pattern reversal VEPs (check size 15′, contrast 50%) were recorded before, and every 30 min after the start of the clamp. Basal VEP latencies and amplitudes were normal bilaterally in nine patients. No significant changes in pattern reversal and flash VEP parameters were observed after the induction or during the clamp period. None of the neurophysiological parameters evaluated during the test was related to the duration of the disease, the basal VEP latency or amplitude or the presence of retinopathy. Our data suggest that the neurophysiological abnormalities detected in insulin-dependent diabetic patients are due to structural involvement of the central nervous pathways and not to functional damage induced by acute short-term hyperglycaemia.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2242
    Keywords: Quantitative genetics ; Recurrent selection ; Partial resistance ; Magnaporthe grisea ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The CNA-IRAT 5 upland rice population has been improved for 4 years by recurrent selection for blast resistance in Brazil. In order to predict the efficiency of recurrent selection in different test systems and to compare the relative advantage of hybrids versus pure line breeding, a combined genetic analysis of partial blast resistance in the CNA-IRAT 5 population was undertaken. A three-level hierarchical design in inbreeding and a factorial design were derived from the base population. Partial blast resistance of lines and hybrids was evaluated in the greenhouse and in the field by inoculation with one virulent blast isolate. The means and genetic variances of the hybrids and lines were estimated. Genetic advance by recurrent selection was predicted from estimates of variance components. The inheritance of partial blast resistance was mainly additive but non-additive effects were detected at both levels of means and variances. Mean heterosis ranged from 4%–8% for lesion size and lesion density to 10–12% for leaf and panicle resistance. High dominance or homozygous dominance variances relative to additive variance and negative covariance between additive and homozygous dominance effects were estimated. A low frequency of favourable alleles for partial resistance would explain the observed organisation of genetic variability in the base population. Recurrent selection will efficiently improve partial blast resistance of the CNA-IRAT 5 population. Genetic advance for line or hybrid values was expected to be higher testing doubled haploid lines than S1 lines, or than general combining ability. Two components of partial resistance assessed in the greenhouse, lesion size and lesion density, could be used as indirect selection criteria to improve field resistance. On the whole, hybrid breeding for partial blast resistance appeared to be slightly more advantageous than pure line breeding.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2242
    Keywords: Key words Quantitative genetics ; Recurrent selection ; Partial resistance ; Magnaporthe grisea ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The CNA-IRAT 5 upland rice population has been improved for 4 years by recurrent selection for blast resistance in Brazil. In order to predict the efficiency of recurrent selection in different test systems and to compare the relative advantage of hybrids versus pure line breeding, a combined genetic analysis of partial blast resistance in the CNA-IRAT 5 population was undertaken. A three-level hierarchical design in inbreeding and a factorial design were derived from the base population. Partial blast resistance of lines and hybrids was evaluated in the greenhouse and in the field by inoculation with one virulent blast isolate. The means and genetic variances of the hybrids and lines were estimated. Genetic advance by recurrent selection was predicted from estimates of variance components. The inheritance of partial blast resistance was mainly additive but non-additive effects were detected at both levels of means and variances. Mean heterosis ranged from 4%–8% for lesion size and lesion density to 10–12% for leaf and panicle resistance. High dominance or homozygous dominance variances relative to additive variance and negative covariance between additive and homozygous dominance effects were estimated. A low frequency of favourable alleles for partial resistance would explain the observed organisation of genetic variability in the base population. Recurrent selection will efficiently improve partial blast resistance of the CNA-IRAT 5 population. Genetic advance for line or hybrid values was expected to be higher testing doubled haploid lines than S1 lines, or than general combining ability. Two components of partial resistance assessed in the greenhouse, lesion size and lesion density, could be used as indirect selection criteria to improve field resistance. On the whole, hybrid breeding for partial blast resistance appeared to be slightly more advantageous than pure line breeding.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We have studied doping evolution of the temperature dependent local Cu-O displacements in the La2-x Sr x CuO4 superconductor by polarized Cu K-edge extended X-ray absorption fine structure (EXAFS) measurements. While temperature dependent Debye-Waller factor of the Cu-O bonds, measuring the local Cu-O displacements, shows an anomalous increase at low temperature for the underdoped single crystals, we do not find such a dependence for the case of the overdoped system. The results, which are discussed in the light of recent angle resolved photoemission measurements, provide an evidence for some important correlation between the doping dependent electron-lattice interaction, the charge inhomogeneities and the local Cu-O displacements in the copper oxide superconductors.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1126-5442
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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