164 research outputs found

    Defective repair of cisplatin-induced DNA damage caused by reduced XPA protein in testicular germ cell tumours

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    AbstractMetastatic cancer in adults usually has a fatal outcome. In contrast, advanced testicular germ cell tumours are cured in over 80% of patients using cisplatin-based combination chemotherapy [1]. An understanding of why these cells are sensitive to chemotherapeutic drugs is likely to have implications for the treatment of other types of cancer. Earlier measurements indicate that testis tumour cells are hypersensitive to cisplatin and have a low capacity to remove cisplatin-induced DNA damage from the genome [2,3]. We have investigated the nucleotide excision repair (NER) capacity of extracts from the well-defined 833K and GCT27 human testis tumour cell lines. Both had a reduced ability to carry out the incision steps of NER in comparison with extracts from known repair-proficient cells. Immunoblotting revealed that the testis tumour cells had normal amounts of most NER proteins, but low levels of the xeroderma pigmentosum group A protein (XPA) and the ERCC1–XPF endonuclease complex. Addition of XPA specifically conferred full NER capacity on the testis tumour extracts. These results show that a low XPA level in the testis tumour cell lines is sufficient to explain their poor ability to remove cisplatin adducts from DNA and might be a major reason for the high cisplatin sensitivity of testis tumours. Targeted inhibition of XPA could sensitise other types of cells and tumours to cisplatin and broaden the usefulness of this chemotherapeutic agent

    Effect of high impact exercise on femoral neck bone mineral density and T2 relaxation times of articular cartilage in postmenopausal women [Abstract]

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    Effect of high impact exercise on femoral neck bone mineral density and T2 relaxation times of articular cartilage in postmenopausal women [Abstract

    A QCQP Approach to Triangulation

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    Triangulation of a three-dimensional point from at least two noisy 2-D images can be formulated as a quadratically constrained quadratic program. We propose an algorithm to extract candidate solutions to this problem from its semidefinite programming relaxations. We then describe a sufficient condition and a polynomial time test for certifying when such a solution is optimal. This test has no false positives. Experiments indicate that false negatives are rare, and the algorithm has excellent performance in practice. We explain this phenomenon in terms of the geometry of the triangulation problem.Comment: 14 pages, to appear in the proceedings of the 12th European Conference of Computer Vision, Firenze, Italy, 7-13 October 201

    Large-scale pathways-based association study in amyotrophic lateral sclerosis

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    Sporadic amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, most likely results from complex genetic and environmental interactions. Although a number of association studies have been performed in an effort to find genetic components of sporadic ALS, most of them resulted in inconsistent findings due to a small number of genes investigated in relatively small sample sizes, while the replication of results was rarely attempted. Defects in retrograde axonal transport, vesicle trafficking and xenobiotic metabolism have been implicated in neurodegeneration and motor neuron death both in human disease and animal models. To assess the role of common genetic variation in these pathways in susceptibility to sporadic ALS, we performed a pathway-based candidate gene case-control association study with replication. Furthermore, we determined reliability of whole genome amplified DNA in a large-scale association study. In the first stage of the study, 1277 putative functional and tagging SNPs in 134 genes spanning 8.7 Mb were genotyped in 822 British sporadic ALS patients and 872 controls using whole genome amplified DNA. To detect variants with modest effect size and discriminate among false positive findings 19 SNPs showing a trend of association in the initial screen were genotyped in a replication sample of 580 German sporadic ALS patients and 361 controls. We did not detect strong evidence of association with any of the genes investigated in the discovery sample (lowest uncorrected P-value 0.00037, lowest permutation corrected P-value 0.353). None of the suggestive associations was replicated in a second sample, further excluding variants with moderate effect size. We conclude that common variation in the investigated pathways is unlikely to have a major effect on susceptibility to sporadic ALS. The genotyping efficiency was only slightly decreased (∼1%) and genotyping quality was not affected using whole genome amplified DNA. It is reliable for large scale genotyping studies of diseases such as ALS, where DNA sample collections are limited because of low disease prevalence and short survival time. © 2007 The Author(s)
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