2,258 research outputs found

    An evaluation of the Agrobacterium tumefaciens Virulence gene system as a potential diagnostic test for Neuroblastoma.

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    Neuroblastoma is a common pediatric cancer, the prognosis for which is markedly dependent upon the progression of the disease at the time of diagnosis. It has been argued that a mass screening programme for all infants would aid early detection of neuroblastoma and reduce mortality. Neuroblastoma is unusual amongst childhood cancers since the basis for such a test exsists - otherwise asymptomatic patients excrete abnormal amounts of specific phenolic compounds in their urine. The presence of these metabolites at elevated levels is taken as diagnostic of the disease. A number of pilot screening programmes in different parts of the world have shown that a quick, inexpensive and reliable method of screening is needed. One candidate for this is a test based upon the responses of Agrobacterium tumefaciens to compounds with structures similar to those produced as a result of tumour metabolism. This bacterium responds to such phenolic ligands chemotactically and by induction of virulence gene expression. Data presented in this work shows that phenolics secreted by neuroblastoma tumours are incapable of inducing virulence gene expression but are capable of acting as chemoattractants. The role of phosphorylation in VirA/G mediated phenolic chemotaxis is investigated. Evidence is presented that phosphorylation of Vir and G is required for chemotaxis. A novel, highly reproducible and comparible measure bacterial chemotaxis, the chemotactic index is derived and applied

    Smart Symmtries

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    The implications of pseudorandom modalities have been far-reaching and pervasive. After years of appropriate research into online algorithms, we confirm the visualization of congestion control, which em- bodies the intuitive principles of machine learning. In order to achieve this goal, we demonstrate that the transistor and Internet QoS are always incompatible

    An analysis of the determinants of successful horizontal collaborative marketing organisations.

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    Available from British Library Document Supply Centre-DSC:DXN049787 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

    On the timing of retreat of the Loch Lomond (‘Younger Dryas’) Readvance icefield in the SW Scottish Highlands and its wider significance

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    It has long been assumed that the last glacier expansion in the Scottish Highlands, the Loch Lomond Readvance (LLR), resulted from a cold reversal that was broadly coeval with the ‘Younger Dryas’ episode. This view has recently been challenged, with the suggestion that glacier ice had disappeared from Rannoch Moor, one of the main ice accumulation centres in the SW Scottish Highlands, by as early as 12.5 ka, i.e. within the first half of the ‘Younger Dryas’. Here we present new radiocarbon, tephrostratigraphical and pollen-stratigraphical evidence from one of the key sites on Rannoch Moor, the results of an experiment designed to test this hypothesis. Our results not only contradict that concept, but are fully compatible with other evidence from the SW Scottish Highlands that suggests that the LLR glaciers in this area continued to expand until towards the end of the ‘Younger Dryas’ period, and may have persisted in some places after the onset of the Holocene. We consider the possible reasons for this marked divergence in chronology, a matter that is crucial to resolve because the precise timing of the demise of the LLR glaciers has important palaeoclimatic and other implications. In the wider context, we also draw attention to problems with the general use of the term ‘Younger Dryas’ and why we regard the Greenland stratotype unit and term ‘Greenland Stadial 1’ (GS-1) a more secure stratigraphic comparator

    GBRDs over groups of orders ≤100 or of order pq with p, q primes

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    AbstractThere are well-known necessary conditions for the existence of a generalized Bhaskar Rao design over a group G, with block size k=3. It has been conjectured that these necessary conditions are indeed sufficient. We prove that they are sufficient for groups G of order pq where p,q are primes and for groups of all orders ≤100 except possibly 32, 36, 48, 54, 60, 64, 72, 96

    Expression of The αβ T-Cell Receptor Is Necessary for The Generation of The Thymic Medulla

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    The architecture of the thymus of mice that congenitally fail to express the αβ T-cell receptor (TCRαβ) has been examined by immunohistology. In these mice, a defined mutation was introduced into the TCRc gene by homologous recombination. By using antibodies specific for cortical or medullary epithelium and for major histocompatibility complex antigens, the network of cortical epithelium in these mice was shown to be essentially unaltered in comparison with that of normal mice. In contrast, the thymic medulla was considerably reduced in size. This analysis shows that expression of the αβ TCR but not the γδ TCR is obligatory for establishing the thymic medulla and suggests that the growth of medullary epithelial cells may require contact with TCRαβ-expressing cells
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