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  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The fragile X mental retardation syndrome is caused by an expansion of a trinucleotide repeat (CGG)n in the FMR-1 gene. Molecular genetic study of fragile X provides accurate diagnosis and facilitates genetic counseling in families with affected members. We present here the molecular study of 59 Spanish fragile X syndrome families using probe StB 12.3 and the polymerase chain reaction (PCR) of the (CGG)n repeat sequence of the FMR-1 gene. The results obtained have allowed us to characterize 455 individuals, including eight prenatal diagnoses. The clinical diagnosis of fragile X in 89 affected males was confirmed, 137 female carriers were identified (48 of whom were mentally retarded), 176 individuals “at risk” were found not to have the expansion, and 12 cases of normal transmitting males (NTM) were detected. In the sample studied, no de novo mutations were detected, nor any mutation different from that described for the (CGG)n expansion. One nonmentally retarded male was detected as having an unmethylated CpG island for the FMR-1 gene, but with more than 200 CGG repeats (high functioning male). The analysis of the (CGG)n repeat in 208 normal chromosomes gave an allele distribution similar to that in other Caucasoid population groups, with alleles of 29 and 30 CGG repeats accounting for 46% of the chromosomes. The combination of Southern analysis and PCR of the (CGG)n repeat is highly efficient for diagnosis, compared with cytogenetic techniques, especially in the detection of female carriers, NTMs, and prenatal diagnosis, enabling accurate genetic counseling to be provided in all cases.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1019-1032 
    ISSN: 0392-6737
    Keywords: Nuclear magnetic resonance and relaxations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si è spesso assunto che la relazione tra mobilità e risposta NMR dell'acqua nei sistemi biologici (ossia eterogenei dinamicamente in quanto composti da fasi liquide e fasi solide) sia esprimibile mediante le equazioni di rilassamento di Bloembergen-Purcell-Pound (BPP). Però l'uso della teoria BPP richiede la presenza di un sistema tridimensionale, infinito ed isotropo. In questo lavoro si mostra che la mera presenza di superfici solide può far comparire andamenti «alla solido» nella risposta NMR di un liquido la cui dinamica microscopica non è mutata dall'interazione con le superfici. Alcuni di questi effetti «topologici» delle superfici si possono ricondurre alle anomalie della bassa dimensionalità che, da alcuni anni, sono investigate attivamente. L'ordine di grandezza degli effetti «topologici» è stimato per geometrie semplici ed un lavoro, a questo collegato, effettua un confronto tra teoria ed esperimento.
    Abstract: Резюме Предполагается, что существует простое соотношение мечду динамикой воды в гетерогенных системах и ЯМР откликом. Это соотношение обычно выражается с помощью уравнений Бломбергена-Пурселя-Паунда для релаксации и фазовой модели. Однако, использование теории Бломбергена-Пурселя-Паунда предполагает, что движения происходят в изотропном, бесконечном и трехмерном пространстве. Показывается, что наличие твердых поверхностей является причиной появления твердоподобных особенностей в ЯМР отклике жидкости, даже в том случае, если поверхности непосредственно не влияют на динамику. Некоторые из этих «топологических» или «непрямых» поверхностных эффектов являются аналогичными эффектам низкой размерности. Оценивается порядок величин этих эффектов для простых геометрий. В следующей статье проводится сравнение полученных результатов с экспериментом.
    Notes: Summary A simple relationship has been thought to exist between the dynamics of water in heterogeneous (liquid-solid) systems and the NMR response. This relationship is usually expressed by the Bloembergen-Purcell-Pound (BPP) equations for relaxation and the phase model. However, a requirement for the use of the BPP theory is that motions take place in an isotropic, infinite and three-dimensional space. It is shown that the mere presence of solid surfaces causes the appearance of solidlike features in the NMR response of the liquid even if its dynamics is directly affected by the surfaces. Some of these «topological» or «indirect» surface effects are of the same kind as the low-dimensionality effects. Their order of magnitude is estimated for simple geometries and by treating the liquid motion in a hydrodynamic approximation. Comparison with the experiment is carried on in a companion paper.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1033-1049 
    ISSN: 0392-6737
    Keywords: Nuclear magnetic resonance and relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Qui si presenta una ricerca sperimentale sulla risposta NMR dell'acqua nel gastrocnemio di rana. I dati sono discussi sulla base dei modelli di «spazio ristretto», sv-. luppati in un lavoro precedente, i quali suppongono l'esistenza di una sola fase d'acquai Alcune caratteristiche della risposta NMR si possono facilmente spiegare con questi modelli, mentre altre mostrano l'esistenza di piú di una «fase» di acqua. Un lavoro di reinterpretazione di dati NMR è stato fatto esaminando lavori condotti su sistemi biologici e modello. Se ne trae il suggerimento che è spesso piú conveniente interpretali dati in termini di una sola specie acquosa, con mobilità media minore di quella della H2O libera, piuttosto che in termini di molte fasi, la caratterizzazione delle quali è piú che mai incerta.
    Abstract: Резюме Предлагаются экстенсивные исследования ЯМР отклика воды в мускульной ткани. Наши данные сравниваются с результатами, полученными в предыдущей работе, в которой развита «клеточная модель», предполагающая существование одной фазы воды. С помощью этих «клеточных моделей» легко объясняются некоторые особенности ЯМР отклика. Однако, другие особенности указывают на существование других фаз воды. Проводится анализ ЯМР данных для биологических и модельных систем, изученных в литературе. Мы предполагаем, что в большинстве случаев наиболее подходящей является интерпретация ЯМР данных в терминах одной фазы воды со средней подвижностью, соответствующей подвижности свободной воды, а не в термиаах несклльких фаз.
    Notes: Summary An extensive investigation of water NMR response in the muscular tissue (frog gastrocnemius) is presented. Our data are compared with the predictions of the «cage models» (discussed in a companion paper), which envisions a single water phase subjected to topological constraints. Several features of the NMR response are easily accounted for by the cage models. Instead, other features give clear evidence for the existence of different phases of water. We performed also an analysis of NMR data for biological and model systems studied in the literature. We suggest that, in most cases, it is more appropriate to interpret NMR data in terms of a single water phase with an average mobility somewhat reduced with respect to that of free water, rather than in terms of several ill-characterized phases.
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 5141-5145 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: X-ray diffraction measurements have been performed on glasses of the AgX–Ag2O–B2O3 (X=Br,Cl) systems. The only meaningful structural detail of the radial distribution functions is due to Ag–X interactions. The mean numbers of Ag–X contacts has been obtained through analysis of the high-angle partial structure functions si(s), calculated by subtracting experimental structure function of the Ag2O–B2O3 glasses from that of the corresponding AgX–doped glasses. Calculations have been also performed for AgI–Ag2O–B2O3 glasses, and comparison between the results from systems containing different halides is made. The average number of Ag–X contacts is very similar in samples at equimolar composition, thus suggesting a close structural feature in AgX–doped glasses.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 17 (1990), S. 0 
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The CCGG and GCGC sites of the human HLA-DRα gene are hypermethylated in human tissues (including B-lymphocytes, T-lymphocytes, muscle, brain, sperm, skin, kidney, suprarenal and mammary glands) and three B-lymphoid cell lines. Therefore, the HLA-DRα gene can be transcribed even though extensively methylated. The only exception to the hypermethylated state of the HLA-DRα gene is represented by one or both of the two HhaI sites (H1 and H2) localized in the 5’portion of the gene. Analysis of the computer-generated secondary structure of the HLA-DRα mRNA suggests that the H1 and H2 sites belong to a region (5′-GAGCGCCCA-3′/5′-UGAGCGCUC-3′) exhibiting extensive base pairing. Therefore, unmethylation of these CG sites can contribute in preventing mCG→TG/CA changes in this region, which would lead to extensive alterations of the secondary structure of the 5’portion of the HLA-DRα MRNA.On the other hand, the selective pressure to maintain unaltered the methylated CG dinucleotides in the coding regions of the HLA-DRα gene could be due to codon restrictions, since the majority of the methylation-related CG→TG or CG→CA variations would generate aminoacid changes.Accordingly, the analysis of different HLA-DRα genomic sequences indicates that variations of the CpG dinucleotides occur only in the non-coding portions of the HLA-DRα gene.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 1191 (1994), S. 27-32 
    ISSN: 0005-2736
    Keywords: Brush-border membrane vesicle ; Chemical modification ; Lepidopteran larva ; Leucine transport ; Phenylglyoxal ; Potassium ion/leucine cotransport
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part B: Biochemistry and 104 (1993), S. 375-379 
    ISSN: 0305-0491
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 95 (1991), S. 1690-1693 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Pesticide Biochemistry and Physiology 50 (1994), S. 15-22 
    ISSN: 0048-3575
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Instruments and Methods in Physics Research Section A: 325 (1993), S. 417-428 
    ISSN: 0168-9002
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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