45 research outputs found

    Ionizing Radiation in Glioblastoma Initiating Cells

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    Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with a median survival of 12–15 months with treatment consisting of surgical resection followed by ionizing radiation (IR) and chemotherapy. Even aggressive treatment is often palliative due to near universal recurrence. Therapeutic resistance has been linked to a subpopulation of GBM cells with stem cell-like properties termed GBM initiating cells (GICs). Recent efforts have focused on elucidating resistance mechanisms activated in GICs in response to IR. Among these, GICs preferentially activate the DNA damage response (DDR) to result in a faster rate of double-strand break (DSB) repair induced by IR as compared to the bulk tumor cells. IR also activates NOTCH and the hepatic growth factor (HGF) receptor, c-MET, signaling cascades that play critical roles in promoting proliferation, invasion, and resistance to apoptosis. These pathways are preferentially activated in GICs and represent targets for pharmacologic intervention. While IR provides the benefit of improved survival, it paradoxically promotes selection of more malignant cellular phenotypes of GBM. As reviewed here, finding effective combinations of radiation and molecular inhibitors to target GICs and non-GICs is essential for the development of more effective therapies

    Study of tractive efficiency as an effect of ballast and tire inflation pressure in sandy loam soil

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    The experiments were conducted in sandy loam soil in stubble field.  Tillage operations were performed using   55 hp tractor with two bottom mouldboard plough and disc plough for four combinations of rear and front ballast (i.e. no ballast, 90 daN front, 90 daN front and 200 daN rear, 200 daN rear) and four combinations of inflation pressure in front and rear tires (i.e. 90 kPa rear and 140 kPa front, 90 kPa rear and 200 kPa front, 130 kPa rear and 140 kPa front and 130 kPa rear and 200 kPa front tire) to study their effects on tractive efficiency of tractor for primary tillage operations.  The test was conducted at recommended speed of operation 2.7 - 4 km h-1.  It was found from the results that combination of 200 daN rear ballast and inflation pressure of 130 kPa at rear, 200 kPa at front was found suitable for improving the performance of agricultural tractor with maximum tractive efficiency of 72.43% and 71.27% for mouldboard plough and disc plough respectively.   Keywords: tractor, ballast, inflation pressure, plough, tractive efficiency, sandy loam, primary tillag

    The PTEN and INK4A/ARF tumor suppressors maintain myelolymphoid homeostasis and cooperate to constrain histiocytic sarcoma development in humans.

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    Histiocytic sarcoma (HS) is a rare malignant proliferation of histiocytes of uncertain molecular pathogenesis. Here, genetic analysis of coincident loss of Pten and Ink4a/Arf tumor suppressors in the mouse revealed a neoplastic phenotype dominated by a premalignant expansion of biphenotypic myelolymphoid cells followed by the development of HS. Pten protein loss occurred only in the histiocytic portion of tumors, suggesting a stepwise genetic inactivation in the generation of HS. Similarly, human HS showed genetic or epigenetic inactivation of PTEN, p16(INK4A), and p14(ARF), supporting the relevance of this genetically engineered mouse model of HS. These genetic and translational observations establish a cooperative role of Pten and Ink4a/Arf in the development of HS and provide mechanistic insights into the pathogenesis of human HS
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