682 research outputs found

    Immunocytochemical Demonstration of Na + ,K + -ATPase in Internodal Axolemma of Myelinated Fibers of Rat Sciatic and Optic Nerves

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    We used postembedding electron microscopic immunocytochemistry with colloidal gold to determine the ultrastructural distribution of Na + ,K + -ATPase in the sciatic and optic nerves of the rat. Using a polyclonal antiserum raised against the denatured catalytic subunit of brain Na + ,K + -ATPase, we found immunoreactivity along the internodal axolemma of myelinated fibers in both nerves. This antiserum did not produce labeling of nodal axolemma. These results suggest that an important site of energy-dependent sodium-potassium exchange is along the internodal axolemma of myelinated fibers in the mammalian CNS and PNS and that there may be differences between the internodal and nodal forms of the enzyme.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66444/1/j.1471-4159.1991.tb02114.x.pd

    Growing a Software Language for Hardware Design

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    The Liquid Metal project at IBM Research aimed to design and implement a new programming language called Lime to address some of the challenges posed by heterogeneous systems. Lime is a Java-compatible programming language with features designed to facilitate high level synthesis to hardware (FPGAs). This article reviews the language design from the outset, and highlights some of the earliest design decisions. We also describe how these decisions were revised recently to accommodate important requirements that arise in networking and cryptography

    Monofunctional Platinum-DNA Adducts Are Strong Inhibitors of Transcription and Substrates for Nucleotide Excision Repair in Live Mammalian Cells

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    To overcome drug resistance and reduce the side effects of cisplatin, a widely used antineoplastic agent, major efforts have been made to develop next generation platinum-based anticancer drugs. Because cisplatin–DNA adducts block RNA polymerase II unless removed by transcription-coupled excision repair, compounds that react similarly but elude repair are desirable. The monofunctional platinum agent pyriplatin displays antitumor activity in mice, a cytotoxicity profile in cell cultures distinct from that of cisplatin, and a unique in vitro transcription inhibition mechanism. In this study, we incorporated pyriplatin globally or site specifically into luciferase reporter vectors to examine its transcription inhibition profiles in live mammalian cells. Monofunctional pyriplatin reacted with plasmid DNA as efficiently as bifunctional cisplatin and inhibited transcription as strongly as cisplatin in various mammalian cells. Using repair-defective nucleotide excision repair (NER)-, mismatch repair-, and single-strand break repair–deficient cells, we show that NER is mainly responsible for removal of pyriplatin–DNA adducts. These findings reveal that the mechanism by which pyriplatin generates its antitumor activity is very similar to that of cisplatin, despite the chemically different nature of their DNA adducts, further supporting a role for monofunctional platinum anticancer agents in human cancer therapy. This information also provides support for the validity of the proposed mechanism of action of cisplatin and provides a rational basis for the design of more potent platinum anticancer drug candidates using a monofunctional DNA-damaging strategy.National Cancer Institute (U.S.) (Grant Number CA034992

    Discovery of host-directed modulators of virus infection by probing the SARS-CoV-2-host protein-protein interaction network

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    The ongoing coronavirus disease 2019 (COVID-19) pandemic has highlighted the need to better understand virus-host interactions. We developed a network-based method that expands the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-host protein interaction network and identifies host targets that modulate viral infection. To disrupt the SARS-CoV-2 interactome, we systematically probed for potent compounds that selectively target the identified host proteins with high expression in cells relevant to COVID-19. We experimentally tested seven chemical inhibitors of the identified host proteins for modulation of SARS-CoV-2 infection in human cells that express ACE2 and TMPRSS2. Inhibition of the epigenetic regulators bromodomain-containing protein 4 (BRD4) and histone deacetylase 2 (HDAC2), along with ubiquitin-specific peptidase (USP10), enhanced SARS-CoV-2 infection. Such proviral effect was observed upon treatment with compounds JQ1, vorinostat, romidepsin and spautin-1, when measured by cytopathic effect and validated by viral RNA assays, suggesting that the host proteins HDAC2, BRD4 and USP10 have antiviral functions. We observed marked differences in antiviral effects across cell lines, which may have consequences for identification of selective modulators of viral infection or potential antiviral therapeutics. While network-based approaches enable systematic identification of host targets and selective compounds that may modulate the SARS-CoV-2 interactome, further developments are warranted to increase their accuracy and cell-context specificity.Peer reviewe

    Oncogenic PIK3CA Mutations Reprogram Glutamine Metabolism in Colorectal Cancer

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    Cancer cells often require glutamine for growth, thereby distinguishing them from most normal cells. Here we show that PIK3CA mutations reprogram glutamine metabolism by upregulating glutamate pyruvate transaminase 2 (GPT2) in colorectal cancer (CRC) cells, making them more dependent on glutamine. Compared with isogenic wild-type (WT) cells, PIK3CA mutant CRCs convert substantially more glutamine to alpha-ketoglutarate to replenish the tricarboxylic acid cycle and generate ATP. Mutant p110 alpha upregulates GPT2 gene expression through an AKT-independent, PDK1-RSK2-ATF4 signalling axis. Moreover, aminooxyacetate, which inhibits the enzymatic activity of aminotransferases including GPT2, suppresses xenograft tumour growth of CRCs with PIK3CA mutations, but not with WT PIK3CA. Together, these data establish oncogenic PIK3CA mutations as a cause of glutamine dependency in CRCs and suggest that targeting glutamine metabolism may be an effective approach to treat CRC patients harbouring PIK3CA mutations

    Oncogenic PIK3CA Mutations Reprogram Glutamine Metabolism in Colorectal Cancer

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    Cancer cells often require glutamine for growth, thereby distinguishing them from most normal cells. Here we show that PIK3CA mutations reprogram glutamine metabolism by upregulating glutamate pyruvate transaminase 2 (GPT2) in colorectal cancer (CRC) cells, making them more dependent on glutamine. Compared with isogenic wild-type (WT) cells, PIK3CA mutant CRCs convert substantially more glutamine to alpha-ketoglutarate to replenish the tricarboxylic acid cycle and generate ATP. Mutant p110 alpha upregulates GPT2 gene expression through an AKT-independent, PDK1-RSK2-ATF4 signalling axis. Moreover, aminooxyacetate, which inhibits the enzymatic activity of aminotransferases including GPT2, suppresses xenograft tumour growth of CRCs with PIK3CA mutations, but not with WT PIK3CA. Together, these data establish oncogenic PIK3CA mutations as a cause of glutamine dependency in CRCs and suggest that targeting glutamine metabolism may be an effective approach to treat CRC patients harbouring PIK3CA mutations

    Understanding patient acceptance and refusal of HIV testing in the emergency department

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    <p>ABSTRACT</p> <p>Background</p> <p>Despite high rates of patient satisfaction with emergency department (ED) HIV testing, acceptance varies widely. It is thought that patients who decline may be at higher risk for HIV infection, thus we sought to better understand patient acceptance and refusal of ED HIV testing.</p> <p>Methods</p> <p>In-depth interviews with fifty ED patients (28 accepters and 22 decliners of HIV testing) in three ED HIV testing programs that serve vulnerable urban populations in northern California.</p> <p>Results</p> <p>Many factors influenced the decision to accept ED HIV testing, including curiosity, reassurance of negative status, convenience, and opportunity. Similarly, a number of factors influenced the decision to decline HIV testing, including having been tested recently, the perception of being at low risk for HIV infection due to monogamy, abstinence or condom use, and wanting to focus on the medical reason for the ED visit. Both accepters and decliners viewed ED HIV testing favorably and nearly all participants felt comfortable with the testing experience, including the absence of counseling. While many participants who declined an ED HIV test had logical reasons, some participants also made clear that they would prefer not to know their HIV status rather than face psychosocial consequences such as loss of trust in a relationship or disclosure of status in hospital or public health records.</p> <p>Conclusions</p> <p>Testing for HIV in the ED as for any other health problem reduces barriers to testing for some but not all patients. Patients who decline ED HIV testing may have rational reasons, but there are some patients who avoid HIV testing because of psychosocial ramifications. While ED HIV testing is generally acceptable, more targeted approaches to testing are necessary for this subgroup.</p
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