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  • 1
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We screened a total of 92 unrelated patients with neurofibromatosis type 1 (NF1) for mutations in exon 37 of the NF1 gene, by using temperature gradient gel electrophoresis. Two novel mutations were found: a 4 bp deletion in a so-called quasi-symmetric element (6789delTTAC) and a recurrent nonsense mutation, which was identified in two unrelated patients, at codon 2264 (C6792A). The independent origin of the latter mutation in two families was confirmed by haplotype analysis. The nonsense mutation and the 4 bp deletion are both predicted to lead to a truncated protein product lacking the Cterminal 20% (aproximately) of its sequence. The occurrence of three independent mutations among 92 NF1 patients at codons 2263–2264 (exon 37) suggests that a specific search for mutations in this area should be undertaken in screening programs for NF1 mutations.
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  • 2
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The diminishing incidence of parasitic infection in westernised societies has been suggested to result in an increased prevalance of asthma. Asthma is a polygenic disease and genome screens have shown that genes on chromosome 5q31–33 are strongly linked to the disease. The gene for the β2-adrenoreceptor is located in this region and two polymorphisms have been identified that result in amino acid changes at positions 16 (ArgGly) and 27 (GlnGlu). To determine whether these polymorphisms influence asthma and parasitic infection, a genotype/phenotype study has been performed on a cohort of 126 children from Coche Island in Venezuela. There is a high incidence of asthma on the island and intestinal helminthiasis is endemic. Genotyping for both polymorphisms was carried out by using the polymerase chain reaction and allele-specific oligonucleotide hybridisation. Genotype frequencies in this cohort were consistent with other studies and both polymorphisms were in significant linkage disequilibrium. Individuals who were homozygous for Arg16 had significantly higher levels of specific IgE to Ascaris lumbricoides (P=0.002), significantly higher A. lumbricoides egg counts (P=0.001) and significantly larger wheal sizes following skin-prick testing with A. lumbricoides allergen (P=0.008). There was no association between either polymorphism and total serum IgE or asthma in this population. A combination of mast cell degranulation and the lung migratory phase of A. lumbricoides larvae may result in bronchoconstriction in infected individuals. These results suggest that the Gly 16 allele confers resistance to high levels of parasitic infection in this population. An alternative explanation for the association is that it may be the result of linkage disequilibrium with other genes in the chromosome 5q31–33 region.
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  • 3
    ISSN: 1432-1246
    Keywords: Bias(epidemiology) ; Cotinine-urine ; Lung neoplasms ; Tobacco smoke pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is no direct evidence that workplace environmental tobacco smoke (ETS) increases lung cancer risk. Demands for regulation of workplace smoking are based on studies reporting increased risk in non-smoking women whose husbands smoke. Although denying smoking can artificially elevate risk estimates, and although many studies reporting an increase have been conducted in Asia, no previous study of smoking habit misclassification has been conducted there. In this study 400 married Japanese women answered questions on smoking and ETS exposure and supplied urine for cotinine analysis. Of 106 with a cotinine/creatinine ratio (CCR) indicating current smoking ( 〉 100 ng/mg), 22 reported never smoking. These misclassified smokers had a median CCR (1408 ng/mg) similar to the 78 self-reported current smokers (1483 ng/mg). Of current smokers, 89.7% had a currently smoking husband, while this was true of 51.0% of non-smokers. Among 264 confirmed nonsmokers (with CCR 〈 100 ng/mg), CCR was non-significantly lower if the husband smoked (11.51 vs 17.98 ng/mg) and was unrelated to various indices of smoking by the husband. Japanese epidemiological studies using “marriage to a smoker” to index ETS exposure may therefore have compared groups with similar ETS exposure, suggesting that associations reported between lung cancer and this index in some of these studies may result from bias. While other biases, including confounding, may also be important, bias resulting from smoking misclassification combined with husband/wife smoking concordance is shown to be of major concern. The high misclassification rates in Japan, much higher than in Western populations, undermine conclusions from epidemiological studies conducted there.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Europhysics news 30 (1999), S. 81-83 
    ISSN: 1432-1092
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
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  • 5
    ISSN: 1433-755X
    Keywords: Key words: Pose estimation; Illumination modelling; Image sequence analysis; Tracking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract: As an object moves through space, it changes its orientation relative to the viewing camera and relative to light sources which illuminate it. As a consequence, the images of the object produced by the viewing camera may change dramatically. Thus, to successfully track a moving object, image changes due to varying pose and illumination must be accounted for. In this paper, we develop a method for object tracking that can not only accommodate large changes in object pose and illumination, but can recover these parameters as well. To do this, we separately model the image variation of the object produced by changes in pose and illumination. To track the object through each image in the sequences, we then locally search the models to find the best match, recovering the object’s orientation and illumination in the process. Throughout, we present experimental results, achieved in real-time, demonstrating the effectiveness of our methods.
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Two subunits from Xenopus, XenNR1G and the “short” subunit XenU1, have previously been coexpressed to form a unitary (NMDA/non-NMDA type) glutamate receptor. We now show that an antibody to XenNR1G or an antibody to XenU1 precipitates the binding sites of both XenNR1G and XenU1, with the recombinant subunits or with solubilised Xenopus brain membranes, i.e., the combination occurs in vivo. The expressed XenU1 subunits are in the cell membrane and oriented correctly. XenU1 binds not only kainate with high affinity (KD 1.2 nM at 25°C), but also the glycine site antagonist 5,7-dichlorokynurenic acid (DCKA). DCKA, GTP, or GTPγS displaces competitively all of the bound [3H]kainate, but glycine has no effect. The results suggest that a common binding site for kainate, DCKA, and GTP can exist on XenU1. In the XenNR1G/XenU1 complex, the kainate affinity is lowered eightfold, whereas the DCKA affinity is considerably increased (KD 147 nM). Only 18% of the binding to the complex has the properties of the NMDA receptor glycine site, the rest being due to switching of the high-affinity kainate site of XenU1 (low-affinity DCKA) to a high-affinity DCKA (low-affinity kainate) conformation. Surprisingly, a mammalian NR2 subunit can also combine with XenU1, and this introduces similar reciprocal changes in the binding of kainate and DCKA. The combined evidence suggests a common basic mode of agonist site formation in different subunit types of the ionotropic glutamate receptors.
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  • 7
    ISSN: 1364-6753
    Keywords: Key words Multiple sclerosis ; Linkage ; Association ; Human leukocyte antigens ; Major histocompatibility complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: ABSTRACT The United Kingdom multiple sclerosis genome screen demonstrated a peak maximum lod score of 2.8 in the HLA region, together with statistically significant excess transmission of the 121-base pair (bp) allele of the tumour necrosis factor-a marker. In order to determine whether this association is independent of the established HLA association, or simply a consequence of the 121-bp allele being part of the same haplotype, we HLA-DR and -DQ typed the 227 sibling-pair families used in the original screen. The expected associations of multiple sclerosis with the DR15 (p=8.7E-18), DQ6 (p=2.0E-09) and DR51 (p=2.8E-16) phenotypes were confirmed, and excess transmission of the DRB1*1501 and DQB1*0602 alleles was demonstrated. Combining HLA typing with the original microsatellite data demonstrated extensive linkage disequilibrium between the 121-bp allele and the 1501-0602 haplotype. Outside this extended haplotype (121-1501-0602), none of the alleles demonstrated significant transmission distortion. Having established the importance of this extended haplotype, we reanalysed the entire genome screen data after excluding those sibling pairs sharing the extended haplotype (n=27). Conditioning the full genome screen data on the basis of identity by state sharing showed that some potential linkage regions identified in the original screen clustered in families, in which the extended haplotype was shared (1p, 2p and 17q), whereas others grouped with those in which it was not (5cen, 7p and Xq). This suggests complexity in the genetics of multiple sclerosis.
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  • 8
    ISSN: 1364-6753
    Keywords: Key words Multiple sclerosis ; Spinocerebellar ataxia ; Association ; Heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Expanded CAG trinucleotide repeats are known to be responsible for five of the autosomal dominant spinocerebellar ataxias (SCA1, SCA2, SCA3, SCA6, and SCA7). We have typed each of these repeats in 226 multiple sclerosis sibling pair families. No expanded repeats were seen, indicating an absence of SCA phenocopies in clinically defined familial multiple sclerosis. However, transmission disequilibrium testing for these repeats demonstrated significant excess transmission of the 22 repeat length allele of the SCA2 gene (P=4.4E-06) in multiple sclerosis patients. This observation is consistent with pleiotropic effects of the SCA2 gene, with a non-dynamic mutation/polymorphism contributing epistatically to susceptibility in multiple sclerosis.
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 373 (1995), S. 31-32 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] JOSEPH Fruton and his wife, Sophia Sim-monds, known as Topsy, were the authors of the first comprehensive textbook of biochemistry, General Biochemistry, published by Wiley in 1953, with a second edition in 1958. At the time this was a very welcome text and did much to establish biochemistry as an ...
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  • 10
    ISSN: 1617-4623
    Keywords: Agglutinins ; Adhesion proteins ; Yeast mating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Saccharomyces cerevisiae cell adhesion protein a-agglutinin is composed of an anchorage subunit (Aga1p) and an adhesion subunit (Aga2p). Although functional a-agglutinin is expressed only by a cells, previous results indicated that AGA1 RNA is expressed in both a and α cells after pheromone induction. Expression of the Aga2p adhesion subunit in a cells allowed a-agglutinability, indicating that a cells express the a-agglutinin anchorage subunit, although no role for Aga1p in α cells has been identified. Most of the a-specific agglutination-defective mutants isolated previously were defective in AGA1; a single mutant (La199) was a candidate for an aga2 mutant. Expression of AGA2 under PGK control allowed secretion of active Aga2p from control strains but did not complement the La199 agglutination defect or allow secretion of Aga2p from La 199, suggesting that the La199 mutation might identify a new gene required for a-agglutinin function. However, the La199 agglutination defect showed tight linkage to aga2::URA3 and did not complement aga2::URA3 in a/a diploids. The aga2 gene cloned from La199 was nonfunctional and contained an ochre mutation. The inability of pPGK-AGA2 to express functional Aga2p in La199 was shown to result from an additional mutation(s) that reduces expression of plasmid-borne genes. AGA2 was mapped to the left arm of chromosome VII approximately 28 cM from the centromere.
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