2,121 research outputs found

    Terminal Pleistocene Alaskan genome reveals first founding population of Native Americans

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    Despite broad agreement that the Americas were initially populated via Beringia, the land bridge that connected far northeast Asia with northwestern North America during the Pleistocene epoch, when and how the peopling of the Americas occurred remains unresolved. Analyses of human remains from Late Pleistocene Alaska are important to resolving the timing and dispersal of these populations. The remains of two infants were recovered at Upward Sun River (USR), and have been dated to around 11.5 thousand years ago (ka). Here, by sequencing the USR1 genome to an average coverage of approximately 17 times, we show that USR1 is most closely related to Native Americans, but falls basal to all previously sequenced contemporary and ancient Native Americans. As such, USR1 represents a distinct Ancient Beringian population. Using demographic modelling, we infer that the Ancient Beringian population and ancestors of other Native Americans descended from a single founding population that initially split from East Asians around 36 ± 1.5 ka, with gene flow persisting until around 25 ± 1.1 ka. Gene flow from ancient north Eurasians into all Native Americans took place 25–20 ka, with Ancient Beringians branching off around 22–18.1 ka. Our findings support a long-term genetic structure in ancestral Native Americans, consistent with the Beringian ‘standstill model’. We show that the basal northern and southern Native American branches, to which all other Native Americans belong, diverged around 17.5–14.6 ka, and that this probably occurred south of the North American ice sheets. We also show that after 11.5 ka, some of the northern Native American populations received gene flow from a Siberian population most closely related to Koryaks, but not Palaeo-Eskimos, Inuits or Kets, and that Native American gene flow into Inuits was through northern and not southern Native American groups. Our findings further suggest that the far-northern North American presence of northern Native Americans is from a back migration that replaced or absorbed the initial founding population of Ancient Beringians

    PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

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    Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al

    Chronic dialysis in the infant less than 1 year of age

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    Dialysis in the infant carries a mortality rate of 16%. Institution of dialysis may be the result of adequate nutritional intake, but avoidance of nutritional intake should never be seen as a way to prevent dialysis. Increased caloric intake, usually via enteral feeding tubes, is needed for optimal growth in the infant with end-stage renal disease (ESRD) in order to attain adequate nutrition with resulting good growth. “Renal” formulae may be constituted as dilute (as in the polyuric infant) or concentrated (as in the anuric infant) to fit the infants needs. Peritoneal dialysis (PD) is the usual mode of renal replacement therapy (97%), with access via a surgically placed cuffed catheter with attention to the placement of the exit site in order to avoid fecal or urinary contamination. PD volumes of 30–40 ml/kg per pass or 800–1,200 ml/m 2 per pass usually result in dialysis adequacy. Additional dietary sodium (3–5 mEq/kg per day) and protein (3–4 g/kg per day) are needed, due to sodium and protein losses in the dialysate. Protein losses are associated with significant infectious morbidity and nonresponsiveness to routine immunizations. Hemodialysis (HD) can be performed either as single- or dual-needle access that have minimal dead space (less then 2 ml) and recirculation rate (less then 5%). Attnetion to extracorporeal blood volume (<10% of intravascular volume), blood flow rates (3–5 ml/kg per min), heparinization (activated clotting times), ultrafiltration (ultrafiltration monitor), and temperature control is imperative during each treatment. Because infants' nutrition is mostly fluid, HD may be needed 4–6 days/week (especially in the oligoanuric infant) to avoid excessive volume overload between treatments. At the end of the treatment a slow blood return with minimal saline rinse is needed to avoid hemodynamic compromise. Infant dialysis, although technically challenging with a significant morbidity and mortality rate, can be safely carried out in the infant with ESRD but requires infant-specific equipment and trained personnel.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47836/1/467_2004_Article_BF00867678.pd

    Surgical treatment of scoliosis: a review of techniques currently applied

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    In this review, basic knowledge and recent innovation of surgical treatment for scoliosis will be described. Surgical treatment for scoliosis is indicated, in general, for the curve exceeding 45 or 50 degrees by the Cobb's method on the ground that

    The SAM Domain of Human TEL2 Can Abrogate Transcriptional Output from TEL1 (ETV-6) and ETS1/ETS2

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    Regulation of gene expression downstream of the Receptor Tyrosine Kinase signaling pathway in Drosophila relies on a transcriptional effector network featuring two conserved Ets family proteins, Yan and Pointed, known as TEL1 (ETV6) and ETS1/ETS2, respectively, in mammals. As in Drosophila, both TEL1 and ETS1/ETS2 operate as Ras pathway transcriptional effectors and misregulated activity of either factor has been implicated in many human leukemias and solid tumors. Providing essential regulation to the Drosophila network, direct interactions with the SAM domain protein Mae attenuate both Yan-mediated repression and PointedP2-mediated transcriptional activation. Given the critical contributions of Mae to the Drosophila circuitry, we investigated whether the human Ets factors TEL1 and ETS1/ETS2 could be subject to analogous regulation. Here we demonstrate that the SAM domain of human TEL2 can inhibit the transcriptional activities of ETS1/2 and TEL1. Drosophila Mae can also attenuate human ETS1/ETS2 function, suggesting there could be cross-species conservation of underlying mechanism. In contrast, Mae is not an effective inhibitor of TEL1, suggesting the mode of TEL2SAM-mediated inhibition of TEL1 may be distinct from how Drosophila Mae antagonizes Yan. Together our results reveal both further similarities and new differences between the mammalian and Drosophila networks and more broadly suggest that SAM domain-mediated interactions could provide an effective mechanism for modulating output from the TEL1 and ETS1/2 oncogenes

    An approach to heroin use disorder intervention within the South African context: A content analysis study

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    <p>Abstract</p> <p>Background</p> <p>The field of heroin use disorder intervention has been in transition in South Africa since the outbreak of the heroin epidemic. Yet despite growing evidence of an association between heroin users' use of supplementary intervention services and intervention outcomes, heroin use disorder intervention programmes in South Africa generally fail to meet international research-based intervention standards.</p> <p>Methods</p> <p>Semi-structured interviews with ten heroin use disorder specialists were conducted and the interviews were subjected to content analysis.</p> <p>Results and Discussion</p> <p>In terms of theory and practice, findings of the study suggest that the field of heroin use disorder intervention in South Africa remains fragmented and transitional. Specifically, limited strategic public health care polices that address the syndromes' complexities have been implemented within the South Africa context.</p> <p>Conclusions</p> <p>Although many interventions and procedures have begun to be integrated routinely into heroin use disorder clinical practice within the South African context, comorbidity factors, such as psychiatric illness and HIV/AIDS, need to be more cogently addressed. Pragmatic and evidence-based public health care policies designed to reduce the harmful consequences associated with heroin use still needs to be implemented in the South African context.</p

    Measurement of the branching fraction and CP content for the decay B(0) -> D(*+)D(*-)

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    This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APS.We report a measurement of the branching fraction of the decay B0→D*+D*- and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4  fb-1 collected at the Υ(4S) resonance during 1999–2000, we have reconstructed 38 candidate signal events in the mode B0→D*+D*- with an estimated background of 6.2±0.5 events. From these events, we determine the branching fraction to be B(B0→D*+D*-)=[8.3±1.6(stat)±1.2(syst)]×10-4. The measured CP-odd fraction of the final state is 0.22±0.18(stat)±0.03(syst).This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the A.P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation

    Molecular biology of breast cancer metastasis Molecular expression of vascular markers by aggressive breast cancer cells

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    During embryogenesis, the formation of primary vascular networks occurs via the processes of vasculogenesis and angiogenesis. In uveal melanoma, vasculogenic mimicry describes the 'embryonic-like' ability of aggressive, but not nonaggressive, tumor cells to form networks surrounding spheroids of tumor cells in three-dimensional culture; these recapitulate the patterned networks seen in patients' aggressive tumors and correlates with poor prognosis. The molecular profile of these aggressive tumor cells suggests that they have a deregulated genotype, capable of expressing vascular phenotypes. Similarly, the embryonic-like phenotype expressed by the aggressive human breast cancer cells is associated with their ability to express a variety of vascular markers. These studies may offer new insights for consideration in breast cancer diagnosis and therapeutic intervention strategies

    Search for rare quark-annihilation decays, B --> Ds(*) Phi

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    We report on searches for B- --> Ds- Phi and B- --> Ds*- Phi. In the context of the Standard Model, these decays are expected to be highly suppressed since they proceed through annihilation of the b and u-bar quarks in the B- meson. Our results are based on 234 million Upsilon(4S) --> B Bbar decays collected with the BABAR detector at SLAC. We find no evidence for these decays, and we set Bayesian 90% confidence level upper limits on the branching fractions BF(B- --> Ds- Phi) Ds*- Phi)<1.2x10^(-5). These results are consistent with Standard Model expectations.Comment: 8 pages, 3 postscript figues, submitted to Phys. Rev. D (Rapid Communications
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