Publications by authors named "Christopher A Klug"

The role of aberrant glycosylation in pancreatic ductal adenocarcinoma (PDAC) remains an under-investigated area of research. In this study, we determined that ST6 β-galactoside α2,6 sialyltransferase 1 (ST6GAL1), which adds α2,6-linked sialic acids to N-glycosylated proteins, was upregulated in patients with early-stage PDAC and was further increased in advanced disease. A tumor-promoting function for ST6GAL1 was elucidated using tumor xenograft experiments with human PDAC cells.

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This manuscript describes the chemical transformations that occur during hydrolysis of uranium tetrafluoride (UF) due to its storage in humid air (85% and 50% relative humidity) at ambient temperatures. This hydrolysis was previously reported to proceed slowly or not at all (depending on the percent relative humidity); however, previous reports relied primarily on X-ray diffraction methods to probe uranium speciation. In our report, we employ a battery of physiochemical probing techniques to explore potential hydrolysis, including Raman spectroscopy, powder X-ray diffraction, F nuclear magnetic resonance spectroscopy, scanning electron microscopy, and focused ion beam microscopy with energy-dispersive X-ray spectroscopy.

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In the structures of 1:1 and 1:2 adducts of phosphanetricarbo-nitrile (CNP) with 1,4-di-aza-bicyclo-[2.2.2]octane (CHN), the 1:1 adduct crystallizes in the ortho-rhom-bic space group, , with four formula units in the unit cell (' = 0.

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Mitogen-activated protein kinases (MAPKs) are inactivated by dual-specificity phosphatases (DUSPs), the activities of which are tightly regulated during cell differentiation. Using knockdown screening and single-cell transcriptional analysis, we demonstrate that DUSP4 is the phosphatase that specifically inactivates p38 kinase to promote megakaryocyte (Mk) differentiation. Mechanistically, PRMT1-mediated methylation of DUSP4 triggers its ubiquitinylation by an E3 ligase HUWE1.

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Uranium tetrafluoride (UF) is an important intermediate in the production of UF and uranium metal. Room temperature hydrolysis of UF was investigated using a combination of Fluorine-19 nuclear magnetic resonance spectroscopy (F NMR), Raman and infrared spectroscopy, powder X-ray diffraction, and microscopy measurements. UF(HO) was identified as the primary solid hydrolysis product when anhydrous UF was stirred in deionized water.

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Power storage devices such as batteries are a crucial part of modern technology. The development and use of batteries has accelerated in the past decades, yet there are only a few techniques that allow gathering vital information from battery cells in a nonivasive fashion. A widely used technique to investigate batteries is electrical impedance spectroscopy (EIS), which provides information on how the impedance of a cell changes as a function of the frequency of applied alternating currents.

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Rechargeable batteries are notoriously difficult to examine nondestructively, and the obscurity of many failure modes provides a strong motivation for developing efficient and detailed diagnostic techniques that can provide information during realistic operating conditions. In-situ NMR spectroscopy has become a powerful technique for the study of electrochemical processes, but has mostly been limited to laboratory cells. One significant challenge to applying this method to commercial cells has been that the radiofrequency, required for NMR excitation and detection, cannot easily penetrate the battery casing due to the skin depth.

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Dynamic regulation of histone modification enzymes such as PRMT1 (protein arginine methyltransferase 1) determines the ordered epigenetic transitions in hematopoiesis. Sorting cells according to the expression levels of histone modification enzymes may further define subpopulations in hematopoietic lineages with unique differentiation potentials that are presently defined by surface markers. We discovered a vital near infrared dye, E84, that fluoresces brightly following binding to PRMT1 and excitation with a red laser.

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We present an approach to increase the detection sensitivity of NMR by shortening the spin-lattice relaxation time using transient paramagnetic species created by light irradiation of "optorelaxer" molecules. In the ultimate implementation of this concept, not yet realized here, these transient species are absent during the detection period, thereby avoiding the loss of spectral resolution caused by inhomogeneous broadening from paramagnetic species. Real-time control of NMR relaxation by visible light is demonstrated with Fe(II)(ptz)(BF), (ptz = 1-propyltetrazole), abbreviated FePTZ.

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High-resolution F magic-angle spinning (MAS) NMR spectra were obtained for the uranium-bearing solid uranyl fluoride sesquihydrate (UOF·1.57HO). While there are seven distinct crystallographic fluorine sites, the F NMR spectrum reveals six peaks at -33.

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The automated detection of broad NMR spectra via the controlled stepwise motion of the NMR probe along the field axis of the superconducting solenoid is demonstrated for the detection of F NMR of paramagnetic UF and Pt NMR of supported metal catalysts. The sensitivity advantages of performing these measurements at 2.3 T are discussed with reference to applying this methodology to room temperature in situ electrochemical Pt NMR.

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Water soluble metallic nanoparticles are being developed for a variety of roles ranging from catalysis to drug delivery and as potential contrast agents. We demonstrate direct synthesis of high-quality water-soluble Au, Ag, Pt, Pd, Cu and alloyed AuPt nanoparticles as well as ligand-exchange of FePt, cubic Pt and Au/Pt core/shell nanoparticles using bidentate dithiolane PEG as a universal ligand. Simple chemistry can greatly expand the applications of metal nanoparticles.

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Long-term self-renewing hematopoietic stem cell (LT-HSC) homeostasis within the bone marrow (BM) of adult mammals is regulated by complex interactions between LT-HSC and a number of niche-associated cell types including mesenchymal stromal/stem cells (MSC), osteoblasts (OB), macrophage, and neuronal cells in close proximity with the vasculature. Here, we cloned and functionally characterized a murine BM MSC subpopulation that was uniformly Nestin Lepr Sca-1 CD146 and could be stably propagated with high colony-forming unit fibroblast re-cloning efficiency. MSC synergized with SCF and IL-11 to support a 20-fold expansion in true LT-HSC after 10-days of in vitro coculture.

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The glycosyltransferase ST6Gal-I, which adds α2-6-linked sialic acids to substrate glycoproteins, has been implicated in carcinogenesis; however, the nature of its pathogenic role remains poorly understood. Here we show that ST6Gal-I is upregulated in ovarian and pancreatic carcinomas, enriched in metastatic tumors, and associated with reduced patient survival. Notably, ST6Gal-I upregulation in cancer cells conferred hallmark cancer stem-like cell (CSC) characteristics.

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Epigenetic mechanisms play important regulatory roles in hematopoiesis and hematopoietic stem cell (HSC) function. Subunits of polycomb repressive complex 1 (PRC1), the major histone H2A ubiquitin ligase, are critical for both normal and pathological hematopoiesis; however, it is unclear which of the several counteracting H2A deubiquitinases functions along with PRC1 to control H2A ubiquitination (ubH2A) level and regulates hematopoiesis in vivo. Here we investigated the function of Usp16 in mouse hematopoiesis.

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We have applied a serologic proteomic workflow involving three complementary MS approaches to a tissue-specific Kras(G12D) -knockin mouse model of pancreatic cancer that consistently forms precancerous lesions by 4 months of age. The three proteomics applications were highly complementary and allowed us to survey the entire range of low to high molecular weight serologic proteins. Combined, we identified 121 (49↓, 72↑) unique and statistically relevant serologic biomarkers with 88% previously reported to be associated with cancer and 38% specifically correlated with pancreatic cancer.

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A number of reports have recently emerged with focus on extraction of proteins from formalin-fixed paraffin-embedded (FFPE) tissues for MS analysis; however, reproducibility and robustness as compared to flash frozen controls is generally overlooked. The goal of this study was to identify and validate a practical and highly robust approach for the proteomics analysis of FFPE tissues. FFPE and matched frozen pancreatic tissues obtained from mice (n = 8) were analyzed using 1D-nanoLC-MS(MS)(2) following work up with commercially available kits.

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In this issue of Blood,Matsuura and colleagues provide evidence that loss of GMCSF signaling promotes leukemic progression in association with one of the most frequently observed cytogenetic abnormalities in AML, the t(8;21)(q22;q22) that generates the RUNX1-ETO fusion protein.

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The t(8;21) RUNX1-ETO translocation is one of the most frequent cytogenetic abnormalities in acute myeloid leukemia (AML). In RUNX1-ETO(+) patient samples, differing classes of activating c-KIT receptor tyrosine kinase mutations have been observed. The most common (12%-48%) involves mutations, such as D816V, which occur in the tyrosine kinase domain, whereas another involves mutations within exon 8 in a region mediating receptor dimerization (2%-13% of cases).

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Harnessing the ability of cytotoxic T lymphocytes (CTLs) to recognize and eradicate tumor or pathogen-infected cells is a critical goal of modern immune-based therapies. Although multiple immunization strategies efficiently induce high levels of antigen-specific CTLs, the initial increase is typically followed by a rapid contraction phase resulting in a sharp decline in the frequency of functional CTLs. We describe a novel approach to immunotherapy based on a transplantation of low numbers of antigen-expressing hematopoietic stem cells (HSCs) following nonmyeloablative or partially myeloablative conditioning.

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Superior mechanical properties, rich surface chemistry, and good biocompatibility of diamond nanoparticles make them attractive in biomaterial applications. A multifunctional fluorescent composite bone scaffold material has been produced utilizing a biodegradable polymer, poly(l-lactic acid) (PLLA), and octadecylamine-functionalized nanodiamond (ND-ODA). The uniform dispersion of nanoparticles in the polymer led to significant increase in hardness and Young's modulus of the composites.

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Gene knockout experiments in mice have suggested a hierarchical model of early B cell commitment wherein E2A proteins (E47 and E12) activate early B cell factor (Ebf1), which in turn activates expression of the B cell commitment factor, Pax5. In IL-7 receptor alpha (IL-7Ralpha) knockout mice, B cell development is blocked before B-lineage commitment at the prepro-B cell stage in adult animals. In IL-7Ralpha(-/-) prepro-B cells, E47 is expressed and yet is insufficient to transcriptionally activate the putative downstream target gene, Ebf1.

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Background: The proteome varies with physiologic and disease states. Few studies have been reported that differentiate the proteome of those with pancreatic cancer.

Aim: To apply proteomic-based technologies to body fluids.

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The kidney is capable of regeneration following injury, particularly following acute insults. Although the mechanisms underlying cellular regeneration are incompletely understood, emerging evidence suggests a role for cells of renal origin in the repair and replacement of damaged renal tubule cells. The overall hypothesis of this study is that native kidney cells that reside in a niche in the kidney provide robust contribution to the repair of kidney tubules following injury.

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Inactivation of p15(Ink4b) expression by promoter hypermethylation occurs in up to 80% of acute myeloid leukemia (AML) cases and is particularly common in the FAB-M2 subtype of AML, which is characterized by the presence of the RUNX1-ETO translocation in 40% of cases. To establish whether the loss of p15(Ink4b) contributes to AML progression in association with RUNX1-ETO, we have expressed the RUNX1-ETO fusion protein from a retroviral vector in hematopoietic progenitor cells isolated from wild-type, p15(Ink4b) or p16(Ink4a) knockout bone marrow. Analysis of lethally irradiated recipient mice reconstituted with RUNX1-ETO-expressing cells showed that neither p15(Ink4b) or p16(Ink4a) loss significantly accelerated disease progression over the time period of one year post-transplantation.

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