180 research outputs found

    Health technologies for falls prevention and detection in adult hospital in-patients: a scoping review protocol.

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    Review objective/questions: The objective of this scoping review is to map the evidence relating to the reporting and evaluation of health technologies for the prevention and detection of falls in adult hospital in-patients. The following questions will guide this scoping review: i) What falls prevention and detection health technologies have been reported in the literature? ii) What outcomes have been reported that measure falls prevention and detection health technologies in terms of clinical effectiveness, cost-effectiveness, acceptability and feasibility of use

    Immunological evidence that HMG-CoA reductase kinase-A is the cauliflower homologue of the RKIN1 subfamily of plant protein kinases

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    AbstractThree different antibodies against the RKIN1 and BKIN12 gene products from rye and barley recognized the 58 kDa subunit of HMG-CoA reductase kinase-A (HRK-A) from Brassica oleracea on Western blots. HRK-A was also detected by an antipeptide antibody in enzyme-linked immunoassays, and this was competed by the peptide antigen. HRK-A was not recognized by antibodies against plant, mammalian and Saccharomyces cereviseae relatives of RKIN1, i.e. wheat PKABA1, rat AMP-activated protein kinase and S. cerevisiae Snf1p. RKIN1/HMG-CoA reductase kinase-A are now among the first protein kinases in plants to be well characterized at both the molecular and biochemical levels

    Investigation of LKB1 Ser<sup>431</sup> phosphorylation and Cys<sup>433</sup> farnesylation using mouse knockin analysis reveals an unexpected role of prenylation in regulating AMPK activity

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    The LKB1 tumour suppressor protein kinase functions to activate two isoforms of AMPK (AMP-activated protein kinase) and 12 members of the AMPK-related family of protein kinases. The highly conserved C-terminal residues of LKB1 are phosphorylated (Ser(431)) by PKA (cAMP-dependent protein kinase) and RSK (ribosomal S6 kinase) and farnesylated (Cys(433)) within a CAAX motif. To better define the role that these post-translational modifications play, we created homozygous LKB1(S431A/S431A) and LKB1(C433S/C433S) knockin mice. These animals were viable, fertile and displayed no overt phenotypes. Employing a farnesylation-specific monoclonal antibody that we generated, we established by immunoprecipitation that the vast majority, if not all, of the endogenous LKB1 is prenylated. Levels of LKB1 localized at the membrane of the liver of LKB1(C433S/C433S) mice and their fibroblasts were reduced substantially compared with the wild-type mice, confirming that farnesylation plays a role in mediating membrane association. Although AMPK was activated normally in the LKB1(S431A/S431A) animals, we unexpectedly observed in all of the examined tissues and cells taken from LKB1(C433S/C433S) mice that the basal, as well as that induced by the AMP-mimetic AICAR (5-amino-4-imidazolecarboxamide riboside), AMPK activation, phenformin and muscle contraction were significantly blunted. This resulted in a reduced ability of AICAR to inhibit lipid synthesis in primary hepatocytes isolated from LKB1(C433S/C433S) mice. The activity of several of the AMPK-related kinases analysed [BRSK1 (BR serine/threonine kinase 1), BRSK2, NUAK1 (NUAK family, SNF1-like kinase 1), SIK3 (salt-inducible kinase 3) and MARK4 (MAP/microtubule affinity-regulating kinase 4)] was not affected in tissues derived from LKB1(S431A/S431A) or LKB1(C433S/C433S) mice. Our observations reveal for the first time that farnesylation of LKB1 is required for the activation of AMPK. Previous reports have indicated that a pool of AMPK is localized at the plasma membrane as a result of myristoylation of its regulatory AMPKβ subunit. This raises the possibility that LKB1 farnesylation and myristoylation of AMPKβ might promote the interaction and co-localization of these enzymes on a two-dimensional membrane surface and thereby promote efficient activation of AMPK

    Metabolic phenotype-microRNA data fusion analysis of the systemic consequences of Roux-en-Y gastric bypass surgery.

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    BACKGROUND/OBJECTIVES: Bariatric surgery offers sustained marked weight loss and often remission of type 2 diabetes, yet the mechanisms of establishment of these health benefits are not clear. SUBJECTS/METHODS: We mapped the coordinated systemic responses of gut hormones, the circulating miRNAome and the metabolome in a rat model of Roux-en-Y gastric bypass (RYGB) surgery. RESULTS: The response of circulating microRNAs (miRNAs) to RYGB was striking and selective. Analysis of 14 significantly altered circulating miRNAs within a pathway context was suggestive of modulation of signaling pathways including G protein signaling, neurodegeneration, inflammation, and growth and apoptosis responses. Concomitant alterations in the metabolome indicated increased glucose transport, accelerated glycolysis and inhibited gluconeogenesis in the liver. Of particular significance, we show significantly decreased circulating miRNA-122 levels and a more modest decline in hepatic levels, following surgery. In mechanistic studies, manipulation of miRNA-122 levels in a cell model induced changes in the activity of key enzymes involved in hepatic energy metabolism, glucose transport, glycolysis, tricarboxylic acid cycle, pentose phosphate shunt, fatty-acid oxidation and gluconeogenesis, consistent with the findings of the in vivo surgery-mediated responses, indicating the powerful homeostatic activity of the miRNAs. CONCLUSIONS: The close association between energy metabolism, neuronal signaling and gut microbial metabolites derived from the circulating miRNA, plasma, urine and liver metabolite and gut hormone correlations further supports an enhanced gut-brain signaling, which we suggest is hormonally mediated by both traditional gut hormones and miRNAs. This transomic approach to map the crosstalk between the circulating miRNAome and metabolome offers opportunities to understand complex systems biology within a disease and interventional treatment setting

    LKB1 and AMPK and the cancer-metabolism link - ten years after

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    The identification of a complex containing the tumor suppressor LKB1 as the critical upstream kinase required for the activation of AMP-activated protein kinase (AMPK) by metabolic stress was reported in an article in Journal of Biology in 2003. This finding represented the first clear link between AMPK and cancer. Here we briefly discuss how this discovery came about, and describe some of the insights, especially into the role of AMPK in cancer, that have followed from it. In September 2003, our groups published a joint paper [1] in Journal of Biology (now BMC Biology) that identified the long-sought and elusive upstream kinase acting on AMP-activated protein kinase (AMPK) as a complex containing LKB1, a known tumor suppressor. Similar findings were reported at about the same time by David Carling and Marian Carlson [2] and by Reuben Shaw and Lew Cantley [3]; at the time of writing these three papers have received between them a total of over 2,000 citations. These findings provided a direct link between a protein kinase, AMPK, which at the time was mainly associated with regulation of metabolism, and another protein kinase, LKB1, which was known from genetic studies to be a tumor suppressor. While the idea that cancer is in part a metabolic disorder (first suggested by Warburg in the 1920s [4]) is well recognized today [5], this was not the case in 2003, and our paper perhaps contributed towards its renaissance. The aim of this short review is to recall how we made the original finding, and to discuss some of the directions that these findings have taken the field in the ensuing ten years

    The emerging role of AMPK in the regulation of breathing and oxygen supply

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    Regulation of breathing is critical to our capacity to accommodate deficits in oxygen availability and demand during, for example, sleep and ascent to altitude. It is generally accepted that a fall in arterial oxygen increases afferent discharge from the carotid bodies to the brainstem and thus delivers increased ventilatory drive, which restores oxygen supply and protects against hypoventilation and apnoea. However, the precise molecular mechanisms involved remain unclear. We recently identified as critical to this process the AMP-activated protein kinase (AMPK), which is key to the cell-autonomous regulation of metabolic homoeostasis. This observation is significant for many reasons, not least because recent studies suggest that the gene for the AMPK-α1 catalytic subunit has been subjected to natural selection in high-altitude populations. It would appear, therefore, that evolutionary pressures have led to AMPK being utilized to regulate oxygen delivery and thus energy supply to the body in the short, medium and longer term. Contrary to current consensus, however, our findings suggest that AMPK regulates ventilation at the level of the caudal brainstem, even when afferent input responses from the carotid body are normal. We therefore hypothesize that AMPK integrates local hypoxic stress at defined loci within the brainstem respiratory network with an index of peripheral hypoxic status, namely afferent chemosensory inputs. Allied to this, AMPK is critical to the control of hypoxic pulmonary vasoconstriction and thus ventilation–perfusion matching at the lungs and may also determine oxygen supply to the foetus by, for example, modulating utero-placental blood flow
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