97 results match your criteria eliciting half-maximal


Neurotoxic Zanthoxylum chalybeum root constituents invoke mosquito larval growth retardation through ecdysteroidogenic CYP450s transcriptional perturbations.

Pestic Biochem Physiol 2021 Oct 30;178:104912. Epub 2021 Jun 30.

Centre for Traditional Medicine and Drug Research (CTMDR), Kenya Medical Research Institute (KEMRI), Nairobi, Kenya. Electronic address:

Intracellular effects exerted by phytochemicals eliciting insect growth-retarding responses during vector control intervention remain largely underexplored. We studied the effects of Zanthoxylum chalybeum Engl. (Rutaceae) (ZCE) root derivatives against malaria (Anopheles gambiae) and arbovirus vector (Aedes aegypti) larvae to decipher possible molecular targets. Read More

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October 2021

5-HT receptor-mediated Gα activation in psychiatric disorders: A postmortem study.

World J Biol Psychiatry 2021 09 9;22(7):505-515. Epub 2020 Nov 9.

Laboratory of Neuropharmacology, IUNICS/IdISPa, University of the Balearic Islands (UIB), Palma de Mallorca, Spain.

Objectives: Serotonin-2A (5-HT) receptors play an important role in the regulation of many brain functions that are disturbed in patients with such psychiatric diseases as mood disorders and schizophrenia. The objective of this study was to evaluate 5-HT receptor-mediated signalling pathway through Gα activation in psychiatric patients by using post-mortem brain samples.

Methods: Functional activation of Gα proteins coupled to 5-HT receptors was determined by means of [S]GTPγS binding/immunoprecipitation assay in post-mortem prefrontal cortex of psychiatric patients diagnosed as bipolar disorder (BP), major depressive disorder (MDD), and schizophrenia, and individually matched controls. Read More

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September 2021

Imidazo[2,1-b] [1,3,4]thiadiazoles with antiproliferative activity against primary and gemcitabine-resistant pancreatic cancer cells.

Eur J Med Chem 2020 Mar 25;189:112088. Epub 2020 Jan 25.

Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo, Italy. Electronic address:

A new series of eighteen imidazo [2,1-b] [1,3,4]thiadiazole derivatives was efficiently synthesized and screened for antiproliferative activity against the National Cancer Institute (NCI-60) cell lines panel. Two out of eighteen derivatives, compounds 12a and 12h, showed remarkably cytotoxic activity with the half maximal inhibitory concentration values (IC) ranging from 0.23 to 11. Read More

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Functional coupling of M muscarinic acetylcholine receptor to Gα in dorsolateral prefrontal cortex from patients with psychiatric disorders: a postmortem study.

Eur Arch Psychiatry Clin Neurosci 2020 Oct 5;270(7):869-880. Epub 2019 Dec 5.

Laboratory of Neuropharmacology, IUNICS/IdISPa, University of the Balearic Islands (UIB), Palma de Mallorca, Spain.

Accumulating studies have implicated intracellular signaling through muscarinic acetylcholine receptors (mAChRs) in psychiatric illness. In the present study, carbamylcholine chloride (carbachol)-induced Gα and Gα activation was identified in postmortem human prefrontal cortical membranes. The following two sample cohorts were used: subjects [1], consisting of 40 controls without neuropsychiatric disorders, and subjects [2], consisting of 20 with bipolar disorder (BP), 20 major depressive disorder (MDD), 20 schizophrenia, and 20 controls, strictly sex- and age-matched. Read More

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October 2020

Quantifying agonist activity at G protein-coupled receptors.

J Vis Exp 2011 Dec 26(58):e3179. Epub 2011 Dec 26.

Department of Pharmacology, University of California, Irvine, USA.

When an agonist activates a population of G protein-coupled receptors (GPCRs), it elicits a signaling pathway that culminates in the response of the cell or tissue. This process can be analyzed at the level of a single receptor, a population of receptors, or a downstream response. Here we describe how to analyze the downstream response to obtain an estimate of the agonist affinity constant for the active state of single receptors. Read More

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December 2011

Tubuloglomerular feedback response in the prenatal and postnatal ovine kidney.

Am J Physiol Renal Physiol 2011 Jun 30;300(6):F1368-74. Epub 2011 Mar 30.

Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia.

The tubuloglomerular feedback mechanism (TGF) plays an important role in regulating single-nephron glomerular filtration rate (GFR) by coupling distal tubular flow to arteriolar tone. It is not known whether TGF is active in the developing kidney or whether it can regulate renal vascular tone and thus GFR during intrauterine life. TGF characteristics were examined in late-gestation ovine fetuses and lambs under normovolemic and volume-expanded (VE) conditions. Read More

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Niacin sensitivity and the arachidonic acid pathway in schizophrenia.

Schizophr Res 2010 Sep 24;122(1-3):248-56. Epub 2010 Apr 24.

Behavorial Health and Clinical Neurosciences Division, Portland VA Medical Center, Portland, OR 97239, USA.

Objective: Schizophrenia is associated with a blunted flush response to niacin. Since niacin-induced skin flushing is mediated by vasodilators derived from arachidonic acid (AA), we tested whether the blunted flush response to niacin is a marker of AA deficiency.

Methods: Eight concentrations of methylnicotinate were applied to the forearms of 20 adults with schizophrenia and 20 controls. Read More

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September 2010

Combining human antisera to human leukocyte antigens, HIVgp120 and 70 kDa heat shock protein results in broadly neutralizing activity to HIV-1.

AIDS 2008 Jul;22(11):1267-76

Kings College London, Mucosal Immunology Unit at Guy's Hospital, London SE1 9RT, UK.

Objective: To elicit broadly neutralizing antibody activity by combining polyclonal human serum IgG antibodies with HIVgp120, human leukocyte antigen (HLA) class I or class II and 70 kDa heat shock protein.

Design: : In addition to HIV antigens, HIV-1 virions express HLA class I, HLA class II and 70 kDa heat shock protein molecules, which have quantitative and functional significance. The complementary effect of combining human polyclonal IgG antibodies with these antigens may result in effective broad spectrum neutralizing activity. Read More

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Changes in the in vitro pharmacodynamic properties of metoprolol in atria isolated from spontaneously hypertensive rats.

Clin Exp Pharmacol Physiol 2007 Mar;34(3):161-5

Department of Pharmacology, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina.

1. The present study addressed possible changes in the dissociation constant of metoprolol and its inverse agonist activity in spontaneously hypertensive rats (SHR). In addition, a possible correlation between cardiac hypertrophy and the inverse agonist activity of metoprolol was explored. Read More

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The molecular receptive range of an olfactory receptor in vivo (Drosophila melanogaster Or22a).

J Neurobiol 2006 Dec;66(14):1544-63

Institut für Neurobiologie, Freie Universität Berlin, D-14195 Berlin, Germany.

Understanding how odors are coded within an olfactory system requires knowledge about its input. This is constituted by the molecular receptive ranges (MRR) of olfactory sensory neurons that converge in the glomeruli of the olfactory bulb (vertebrates) or the antennal lobe (AL, insects). Aiming at a comprehensive characterization of MRRs in Drosophila melanogaster we measured odor-evoked calcium responses in olfactory sensory neurons that express the olfactory receptor Or22a. Read More

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December 2006

Dark adaptation of human rod bipolar cells measured from the b-wave of the scotopic electroretinogram.

J Physiol 2006 Sep 15;575(Pt 2):507-26. Epub 2006 Jun 15.

Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.

To examine the dark adaptation of human rod bipolar cells in vivo, we recorded ganzfeld ERGs to (a) a family of flashes of increasing intensity, (b) dim test flashes presented on a range of background intensities, and (c) dim test flashes presented before, and up to 40 min after, exposure to intense illumination eliciting bleaches from a few per cent to near total. The dim flash ERG was characterized by a prominent b-wave response generated principally by rod bipolar cells. In the presence of background illumination the response reached peak earlier and desensitized according to Weber's Law. Read More

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September 2006

5-HT-stimulated [35S]guanosine-5'-O-(3-thio)triphosphate binding as an assay for functional activation of G proteins coupled with 5-HT1B receptors in rat striatal membranes.

Naunyn Schmiedebergs Arch Pharmacol 2006 Feb 21;372(5):335-45. Epub 2006 Feb 21.

Department of Psychiatry, Saitama Medical School, 38 Morohongo, Moroyama-machi, Iruma-gun, Staitama 350-0495, Japan.

Receptor-mediated guanine nucleotide-binding regulatory protein (G protein) activation or functional coupling between receptors and G proteins has been investigated by means of agonist-induced [35S]guanosine-5'-O-(3-thio)triphosphate ([35S]GTPgammaS) binding, especially for the receptor subtypes negatively coupled to adenylyl cyclase through Gi type G proteins. In the present study, 5-HT-stimulated [35S]GTPgammaS binding to rat stritatal membranes was pharmacologically characterized in detail with the help of an extensive series of 5-HT receptor ligands. The optimum experimental conditions for the concentrations of GDP, MgCl2 and NaCl in the assay buffer were initially determined, and the standard assay was performed with 20 microM GDP, 5 mM MgCl2 and 100 mM NaCl. Read More

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February 2006

Influence of neonatal sympathectomy on proximal renal resistance artery function in spontaneously hypertensive rats.

Pflugers Arch 2005 Jan 12;449(4):364-71. Epub 2004 Oct 12.

Institut für Physiologie, Universität Greifswald, Greifswalder Strasse 11c, 17495 Karlsburg, Germany.

Renal transplantation experiments have shown that the kidney contributes to chronic sympathectomy-induced arterial pressure reduction in spontaneously hypertensive rats (SHR). The underlying mechanisms are currently unclear but may include alterations in the function of small renal arteries. Neonatal SHR were sympathectomized by intraperitoneal guanethidine injections and removal of adrenal medullary tissue. Read More

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January 2005

Pharmacokinetic-pharmacodynamic properties of metoprolol in chronic aortic coarctated rats.

Naunyn Schmiedebergs Arch Pharmacol 2004 Jul 22;370(1):1-8. Epub 2004 Jul 22.

Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, C1113AAD, Argentina.

The present study addressed possible alterations in the pharmacodynamic and pharmacokinetic properties of the beta1-adrenoceptor antagonist metoprolol in experimental hypertension induced by abdominal aortic coarctation (ACo). Metoprolol's pharmacokinetics and its relationship with its in vivo chronotropic and blood pressure effect were studied using the microdialysis technique. A pharmacokinetic-pharmacodynamic model with a separate effect compartment was used to analyse the data. Read More

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Inhibition of Ape1 nuclease activity by lead, iron, and cadmium.

Environ Health Perspect 2004 May;112(7):799-804

Laboratory of Molecular Gerontology, Gerontology Research Center, National Institute on Aging, Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, Maryland 21224-6825, USA.

Many environmental metals are co-carcinogens, eliciting their effects via inhibition of DNA repair. Apurinic/apyrimidinic (AP) endonuclease 1 (Ape1) is the major mammalian abasic endonuclease and initiates repair of this cytotoxic/mutagenic lesion by incising the DNA backbone via a Mg(2+)-dependent reaction. In this study we examined the effects of arsenite [As(III)], cadmium [Cd(II)], cobalt [Co(II)], iron [Fe(II)], nickel [Ni(II)], and lead [Pb(II)] at concentrations ranging from 0. Read More

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Effects of alkali metal cations on the labellar water receptor cell of the fleshfly, Boettcherisca peregrina.

J Insect Physiol 1997 Oct;43(11):1031-1038

Department of Physics, Faculty of Science, Nagoya University, Nagoya, Japan

Dose-response relationships of the labellar water receptor cells of the fleshfly, Boettcherisca peregrina, in response to alkali-metal ions were studied electrophysiologically. When cation concentration was raised, the frequency of spikes from the water receptor cells was decreased. We analyzed the data under the assumption that channels on the water receptor membrane open when stimulated with water and are closed by alkali cations or nonelectrolytes. Read More

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October 1997

Basolateral localization of flounder Na+-dicarboxylate cotransporter (fNaDC-3) in the kidney of Pleuronectes americanus.

Pflugers Arch 2003 Aug 21;446(5):578-84. Epub 2003 May 21.

Max-Planck Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.

The purpose of this study was to provide functional and immunocytochemical evidence for the location of the winter flounder ( Pleuronectes americanus) sodium-dicarboxylate cotransporter-3 (fNaDC-3) in the basolateral membrane of proximal tubule cells. fNaDC-3 was expressed in Xenopus laevis oocytes. Lowering the external pH from 7. Read More

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Alpha 1-adrenoceptor-activated cation currents in neurones acutely isolated from rat cardiac parasympathetic ganglia.

J Physiol 2003 Apr 21;548(Pt 1):111-20. Epub 2003 Feb 21.

Cellular and System Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.

The noradrenaline (NA)-induced cation current was investigated in neurones freshly isolated from rat cardiac parasympathetic ganglia using the nystatin-perforated patch recording configuration. Under current-clamp conditions, NA depolarized the membrane, eliciting repetitive action potentials. NA evoked an inward cation current under voltage-clamp conditions at a holding potential of -60 mV. Read More

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Pharmacokinetic-pharmacodynamic modelling of magnesium plasma concentration and blood pressure in preeclamptic women.

Clin Pharmacokinet 2002 ;41(13):1105-13

Department of Biopharmaceutical Sciences, University of California San Francisco, 94143, USA.

Objective: To describe the relationship between plasma magnesium (Mg(2+)) concentration and blood pressure response in pregnant women with preeclampsia.

Methods: Fifty-one preeclamptic women were studied after receiving two consecutive magnesium sulfate infusions (120 mg/kg for 1 hour and 24 mg/kg for 5 hours). Mg(2+) concentration and systolic/diastolic blood pressure were measured at 0, 0. Read More

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Alpha2-adrenoceptors inhibit antidiuretic hormone-stimulated Na+ absorption across tight epithelia (Rana esculenta).

Pflugers Arch 2001 Jun;442(3):346-52

August Krogh Institute, Copenhagen O, Denmark.

In the present study we examined the effect of alpha-adrenergic regulation of active transepithelial Na+ absorption across the isolated frog skin epithelium. alpha-Adrenergic stimulation was achieved by addition of the adrenergic agonist noradrenaline in the presence of the beta-adrenergic blocker propranolol. alpha-Adrenergic stimulation inhibited basal as well as antidiuretic hormone (ADH)-stimulated Na+ transport. Read More

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Trifluoroacetic acid activates ATP-sensitive K(+) channels in rabbit ventricular myocytes.

Authors:
J Han N Kim E Kim

Biochem Biophys Res Commun 2001 Aug;285(5):1136-42

Department of Physiology and Biophysics, College of Medicine, Inje University, 633-165 Gaegeum-Dong, Busanjin-Ku, Busan, 614-735, Korea.

Recent in vivo experimental evidence suggests that isoflurane-induced cardioprotection may involve K(ATP) channel activation during myocardial ischemia. The actual effect of isoflurane on cardioprotective ion conductance, however, such as that mediated by the opening of K(ATP) channels, has been the subject of some controversy in the past. The investigation reported here used a patch-clamp technique to test the hypothesis that a metabolite of isoflurane, trifluoroacetic acid (TFA), contributes to isoflurane-induced cardioprotection via K(ATP) channel activation. Read More

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Pregnenolone sulfate block of GABA(A) receptors: mechanism and involvement of a residue in the M2 region of the alpha subunit.

J Physiol 2001 May;532(Pt 3):673-84

Department of Anesthesiology, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO 63110, USA.

Neurosteroids are produced in the brain, and can have rapid actions on membrane channels of neurons. Pregnenolone sulfate (PS) is a sulfated neurosteroid which reduces the responses of the [gamma]-aminobutyric acid A (GABA(A)) receptor. We analysed the actions of PS on single-channel currents from recombinant GABA(A) receptors formed from [alpha]1, [beta]2 and [gamma]2L subunits. Read More

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Cross-bridge interaction kinetics in rat myocardium are accelerated by strong binding of myosin to the thin filament.

J Physiol 2001 Jan;530(Pt 2):263-72

Department of Physiology, University of Wisconsin School of Medicine, 1300 University Avenue, Madison, WI 53706, USA.

To determine the ability of strong-binding myosin cross-bridges to activate the myocardial thin filament, we examined the Ca2+ dependence of force and cross-bridge interaction kinetics at 15 degrees C in the absence and presence of a strong-binding, non-force-generating derivative of myosin subfragment-1 (NEM-S1) in chemically skinned myocardium from adult rats. Relative to control conditions, application of 6 microM NEM-S1 significantly increased Ca2+-independent tension, measured at pCa 9.0, from 0. Read More

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January 2001

The relationship between hypotonically-induced taurine and K fluxes in trout red blood cells.

Pflugers Arch 2000 Jul;440(3):467-75

University Laboratory of Physiology, University of Oxford, UK.

Hypotonic swelling of teleost erythrocytes activates multiple transport systems leading to the regulatory decrease of cell volume. We have examined using pharmacological manipulation the swelling-induced taurine flux pathway in red blood cells of the rainbow trout and its relationship to swelling-induced K flux pathways. We show that the activation and deactivation of taurine flux is rapid and that the flux is a sigmoidal function of cell volume. Read More

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Influence of inorganic phosphate and energy state on force in skinned cardiac muscle from freshwater turtle and rainbow trout.

Authors:
M A Jensen H Gesser

J Comp Physiol B 1999 Sep;169(6):439-44

Department of Zoophysiology, University of Aarhus, Denmark.

Inorganic phosphate, which increases in the hypoxic cardiac cell, depresses force development. The cardiac muscle of freshwater turtle maintains a remarkably high contractility during hypoxia; this may involve a low sensitivity to phosphate. Therefore, freshwater turtle and rainbow trout were compared with regard to Ca(2+)-activated force in skinned atrial trabeculae in a bath containing 3 mM ATP buffered by 15 mM creatine phosphate in the presence of creatine kinase. Read More

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September 1999

Evidence for a functional role of the cholecystokinin-B/gastrin receptor in the human fetal and adult pancreas.

Diabetes 1999 Oct;48(10):2015-21

INSERM U151, Institut Louis Bugnard, CHU Rangueil, Toulouse, France.

Gastrin (G) and cholecystokinin (CCK) are gastrointestinal neuropeptides that are released into circulation during a meal. G is also transiently expressed during embryogenic and early ontogenic development of the pancreas and is believed to act on islet-cell development. Both peptides act on pancreatic endocrine function; however, the effects are dependent on the species and on cellular and molecular underlying mechanisms that remain poorly characterized. Read More

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October 1999

The properties of the inward rectifier potassium currents in rabbit coronary arterial smooth muscle cells.

Pflugers Arch 1999 Jul;438(2):187-94

Cardiovascular Division, The Lankenau Hospital and Medical Research Center, Wynnewood, PA 19096, USA.

In freshly-isolated, single, smooth muscle cells of rabbit coronary arteries, an inward rectifier K+ current [IK(IR)] was identified using the whole-cell voltage-clamp technique. The current/voltage (I/V) relationship of IK(IR) showed strong inward rectification with a very small outward current when the smooth muscle cells were dialyzed with a pipette solution containing Mg2+. However, dialyzing the cells with a nominally Mg2+-free pipette solution revealed a significant outward current hump in the I/V relation of IK(IR), suggesting that the strong inward rectification of IK(IR) is partly due to the inhibitory effects of internal Mg2+. Read More

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Selective activation of beta3-adrenoceptors by octopamine: comparative studies in mammalian fat cells.

Naunyn Schmiedebergs Arch Pharmacol 1999 Apr;359(4):310-21

Institut National de la Santé et de la Recherche Médicale (INSERM), Unité 317, Institut Fédératif de Recherches 31, CHU Rangueil, Toulouse, France.

Numerous synthetic agonists selectively stimulate beta3-adrenoceptors (ARs). The endogenous catecholamines, noradrenaline and adrenaline, however, stimulate all the beta-AR subtypes, and no selective physiological agonist for beta3-ARs has been described so far. The aim of this study was to investigate whether any naturally occurring amine can stimulate selectively beta3-ARs. Read More

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Cell-specific coupling of PGE2 to different transduction pathways in arginine vasopressin- and glucagon-sensitive segments of the rat renal tubule.

Br J Pharmacol 1999 Feb;126(4):1041-9

CNRS URA 1859, Département de Biologie Cellulaire et Moléculaire, CEA Saclay, France.

1. The aim of the present study was to investigate the transduction pathways elicited by prostaglandin E2 (PGE2) to inhibit hormone-stimulated adenosine 3':5'-cyclic monophosphate (cyclic AMP) accumulation in the outer medullary collecting duct (OMCD) and medullary thick ascending limb (MTAL) microdissected from the rat nephron. 2. Read More

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February 1999

On the mechanism of the enhancement of delayed rectifier K+ current by extracellular ATP in guinea-pig ventricular myocytes.

Pflugers Arch 1999 Apr;437(5):635-42

Department of Physiology, Saga Medical School, Saga 849-8501, Japan.

The effects of extracellular adenosine 5'-triphosphate (ATP) on the delayed rectifier K+ current (IK) were studied in guinea-pig ventricular myocytes using the whole-cell voltage-clamp technique. ATP increased IK concentration dependently with a concentration eliciting a half-maximal response of 1.86 microM and a maximal increase of about 1. Read More

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