28 research outputs found

    DNA Methylation Profiling of the Human Major Histocompatibility Complex: A Pilot Study for the Human Epigenome Project

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    The Human Epigenome Project aims to identify, catalogue, and interpret genome-wide DNA methylation phenomena. Occurring naturally on cytosine bases at cytosine–guanine dinucleotides, DNA methylation is intimately involved in diverse biological processes and the aetiology of many diseases. Differentially methylated cytosines give rise to distinct profiles, thought to be specific for gene activity, tissue type, and disease state. The identification of such methylation variable positions will significantly improve our understanding of genome biology and our ability to diagnose disease. Here, we report the results of the pilot study for the Human Epigenome Project entailing the methylation analysis of the human major histocompatibility complex. This study involved the development of an integrated pipeline for high-throughput methylation analysis using bisulphite DNA sequencing, discovery of methylation variable positions, epigenotyping by matrix-assisted laser desorption/ionisation mass spectrometry, and development of an integrated public database available at http://www.epigenome.org. Our analysis of DNA methylation levels within the major histocompatibility complex, including regulatory exonic and intronic regions associated with 90 genes in multiple tissues and individuals, reveals a bimodal distribution of methylation profiles (i.e., the vast majority of the analysed regions were either hypo- or hypermethylated), tissue specificity, inter-individual variation, and correlation with independent gene expression data

    A Damped Double Dipole UHF RFID Antenna with Application to Wireless Chemiresistive Gas Sensing

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    Ultra High Frequency (UHF) Radio Frequency Identification (RFID) tags provide an inexpensive framework for distributed sensing. Materials such as functionalized carbon nanotubes (CNTs) have been engineered to change in resistance when exposed to a variety of analytes. These materials have been added to RFID tags to create low cost sensors that work at a fixed reader-tag separation distance. This thesis proposes a novel approach to create UHF RFID sensing tags that work independent of distance (within the operating range), and are able to sense changes in resistance of a sensing element with a conductivity similar to that of CNT networks. Simulations of the proposed design show two methods of operation, either by comparing the damping between two resonant peaks, or by shifting the resonant frequency of the RFID tag. The first of the two methods of operation is validated experimentally with surface mount resistors, showing a relative change in of 0.2 for a 35% change in resistance of the sensing element. Then, a printing process is developed for liquid inks comprising CNTs, and RFID tags are fabricated with functionalized CNTs as the active elements. The functionalized CNTs exhibit an irreversible 65% change in resistance at 100ppm NH₃, resulting in the tags demonstrating a relative change in of 0.5 when exposed to 1000ppm NH₃.S.M

    The cellular ratio of immune tolerance (immunoCRIT) is a definite marker for aggressiveness of solid tumors and may explain tumor dissemination patterns.

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    The adaptive immune system is involved in tumor establishment and aggressiveness. Tumors of the ovaries, an immune-privileged organ, spread via transceolomic routes and rarely to distant organs. This is contrary to tumors of non-immune privileged organs, which often disseminate hematogenously to distant organs. Epigenetics-based immune cell quantification allows direct comparison of the immune status in benign and malignant tissues and in blood. Here, we introduce the "cellular ratio of immune tolerance" (immunoCRIT) as defined by the ratio of regulatory T cells to total T lymphocytes. The immunoCRIT was analyzed on 273 benign tissue samples of colorectal, bronchial, renal and ovarian origin as well as in 808 samples from primary colorectal, bronchial, mammary and ovarian cancers. ImmunoCRIT is strongly increased in all cancerous tissues and gradually augmented strictly dependent on tumor aggressiveness. In peripheral blood of ovarian cancer patients, immunoCRIT incrementally increases from primary diagnosis to disease recurrence, at which distant metastases frequently occur. We postulate that non-pathological immunoCRIT values observed in peripheral blood of immune privileged ovarian tumor patients are sufficient to prevent hematogenous spread at primary diagnosis. Contrarily, non-immune privileged tumors establish high immunoCRIT in an immunological environment equivalent to the bloodstream and thus spread hematogenously to distant organs. In summary, our data suggest that the immunoCRIT is a powerful marker for tumor aggressiveness and disease dissemination
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