Publications by authors named "Ian Jeffrey"

Unlabelled: Every year, people drown after falling through ice on rivers and lakes. In some cases, the body of the victim floats up to the underside of the ice, making detection and recovery difficult using traditional search methods with divers. A robust and contact-less sensing system is required to locate drowning victims that does not put rescue teams at risk of falling through the ice themselves.

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A new breast imaging system capable of obtaining ultrasound and microwave scattered-field measurements with minimal or no movement of the breast between measurements has recently been reported. In this work, we describe the methodology that has been developed to generate prior information about the internal structures of the breast based on ultrasound data measured with the dual-mode system. This prior information, estimating both the geometry and complex-valued permittivity of tissues within the breast, is incorporated into the microwave inversion algorithm as a means of enhancing image quality.

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A discontinuous Galerkin formulation of the Contrast Source Inversion algorithm (DGM-CSI) for microwave breast imaging employing a frequency-cycling reconstruction technique has been modified here to include a set of automated stopping criteria that determine a suitable time to shift imaging frequencies and to globally terminate the reconstruction. Recent studies have explored the use of tissue-dependent geometrical mapping of the well-reconstructed real part to its imaginary part as initial guesses during consecutive frequency hops. This practice was shown to improve resulting 2D images of the dielectric properties of synthetic breast models, but a fixed number of iterations was used to halt DGM-CSI inversions arbitrarily.

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Background: Gardasil, a human papillomavirus (HPV) vaccine, began among grade 6 girls in Manitoba, Canada in 2008. In Manitoba, there is evidence that First Nations, Métis, and Inuit women (FNMI) have higher HPV prevalence, lower invasive cervical cancer (ICC) screening, and higher ICC incidence than all other Manitoban (AOM) women. We developed a mathematical model to assess the plausible impact of unequal vaccination coverage among school girls on future cervical cancer incidence.

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Background: We recently demonstrated that increased expression of the RNA-binding protein RBM3 is associated with a favourable prognosis in breast cancer. The aim of this study was to examine the prognostic value of RBM3 mRNA and protein expression in epithelial ovarian cancer (EOC) and the cisplatin response upon RBM3 depletion in a cisplatin-sensitive ovarian cancer cell line.

Methods: RBM3 mRNA expression was analysed in tumors from a cohort of 267 EOC cases (Cohort I) and RBM3 protein expression was analysed using immunohistochemistry (IHC) in an independent cohort of 154 prospectively collected EOC cases (Cohort II).

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Tumour cells are often sensitized by interferons to the effects of tumour necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL). We have demonstrated previously that TRAIL has an inhibitory effect on protein synthesis [Jeffrey IW, Bushell M, Tilleray VJ, Morley S & Clemens MJ (2002) Cancer Res62, 2272-2280] and we have therefore examined the consequences of prior interferon-alpha treatment for the sensitivity of translation to inhibition by TRAIL. Interferon treatment alone has only a minor effect on protein synthesis but it sensitizes both MCF-7 cells and HeLa cells to the downregulation of translation by TRAIL.

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Activation of a temperature-sensitive form of p53 in murine erythroleukaemia cells results in a rapid impairment of protein synthesis that precedes inhibition of cell proliferation and loss of cell viability by several hours. The inhibition of translation is associated with specific cleavages of polypeptide chain initiation factors eIF4GI and eIF4B, a phenomenon previously observed in cells induced to undergo apoptosis in response to other stimuli. Although caspase activity is enhanced in the cells in which p53 is activated, both the effects on translation and the cleavages of the initiation factors are completely resistant to inhibition of caspase activity.

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Recent studies have suggested a role for the Epstein-Barr virus-encoded RNA EBER-1 in malignant transformation. EBER-1 inhibits the activity of the protein kinase PKR, an inhibitor of protein synthesis with tumour suppressor properties. In human 293 cells and murine embryonic fibroblasts, transient expression of EBER-1 promoted total protein synthesis and enhanced the expression of cotransfected reporter genes.

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The dsRNA-activated protein kinase PKR is involved in signal transduction pathways that mediate cellular processes as diverse as cell growth and differentiation, the stress response, and apoptosis. PKR was originally described as an interferon-inducible elF2alpha kinase involved in the antiviral defense mechanism of the cell. The interaction of the kinase with specific viral RNAs has been studied in much detail, but information about cellular mRNAs, which are able to bind and activate PKR, is scarce.

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Exposure of mammalian cells to agents that induce apoptosis results in a rapid and substantial inhibition of protein synthesis. In MCF-7 breast cancer cells, tumor necrosis factor alpha (TNFalpha) and TNF-related apoptosis-inducing ligand inhibit overall translation by a mechanism that requires caspase (but not necessarily caspase-3) activity. This inhibition is associated with the increased phosphorylation of eukaryotic initiation factor (eIF2) alpha, increased association of eIF4E with the inhibitory eIF4E-binding protein (4E-BP1), and specific cleavages of eIF4B and eIF2alpha.

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