18 research outputs found

    Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke

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    BACKGROUND AND PURPOSE: Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data. METHODS: We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics. RESULTS: In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18-3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58-1.35; P=0.566) arterial obstruction (P for interaction 0.017). CONCLUSIONS: Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was underpowered to demonstrate significant treatment benefit or harm among patients with apparently patent arteries. CLINICAL TRIAL REGISTRATION: URL: http://www.isrctn.com. Unique identifier: ISRCTN25765518

    The benefits and harms of intravenous thrombolysis with recombinant tissue plasminogen activator within 6 h of acute ischaemic stroke (the third international stroke trial [IST-3]): a randomised controlled trial

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    BACKGROUND: Thrombolysis is of net benefit in patients with acute ischaemic stroke, who are younger than 80 years of age and are treated within 4路5 h of onset. The third International Stroke Trial (IST-3) sought to determine whether a wider range of patients might benefit up to 6 h from stroke onset. METHODS: In this international, multicentre, randomised, open-treatment trial, patients were allocated to 0路9 mg/kg intravenous recombinant tissue plasminogen activator (rt-PA) or to control. The primary analysis was of the proportion of patients alive and independent, as defined by an Oxford Handicap Score (OHS) of 0-2 at 6 months. The study is registered, ISRCTN25765518. FINDINGS: 3035 patients were enrolled by 156 hospitals in 12 countries. All of these patients were included in the analyses (1515 in the rt-PA group vs 1520 in the control group), of whom 1617 (53%) were older than 80 years of age. At 6 months, 554 (37%) patients in the rt-PA group versus 534 (35%) in the control group were alive and independent (OHS 0-2; adjusted odds ratio [OR] 1路13, 95% CI 0路95-1路35, p=0路181; a non-significant absolute increase of 14/1000, 95% CI -20 to 48). An ordinal analysis showed a significant shift in OHS scores; common OR 1路27 (95% CI 1路10-1路47, p=0路001). Fatal or non-fatal symptomatic intracranial haemorrhage within 7 days occurred in 104 (7%) patients in the rt-PA group versus 16 (1%) in the control group (adjusted OR 6路94, 95% CI 4路07-11路8; absolute excess 58/1000, 95% CI 44-72). More deaths occurred within 7 days in the rt-PA group (163 [11%]) than in the control group (107 [7%], adjusted OR 1路60, 95% CI 1路22-2路08, p=0路001; absolute increase 37/1000, 95% CI 17-57), but between 7 days and 6 months there were fewer deaths in the rt-PA group than in the control group, so that by 6 months, similar numbers, in total, had died (408 [27%] in the rt-PA group vs 407 [27%] in the control group). INTERPRETATION: For the types of patient recruited in IST-3, despite the early hazards, thrombolysis within 6 h improved functional outcome. Benefit did not seem to be diminished in elderly patients. FUNDING: UK Medical Research Council, Health Foundation UK, Stroke Association UK, Research Council of Norway, Arbetsmarknadens Partners Forsakringsbolag (AFA) Insurances Sweden, Swedish Heart Lung Fund, The Foundation of Marianne and Marcus Wallenberg, Polish Ministry of Science and Education, the Australian Heart Foundation, Australian National Health and Medical Research Council (NHMRC), Swiss National Research Foundation, Swiss Heart Foundation, Assessorato alla Sanita, Regione dell'Umbria, Italy, and Danube University

    Identification of a novel ligand binding residue Arg38<sup>(1.35)</sup> in the human gonadotropin-releasing hormone receptor

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    Delineation of peptide ligand binding sites is of fundamental importance in rational drug design and in understanding ligand-induced receptor activation. Molecular modeling and ligand docking to previously experimentally identified binding sites revealed a putative novel interaction between the C terminus of gonadotropin-releasing hormone (GnRH) and Arg38(1.35), located at the extracellular end of transmembrane domain 1 of the human GnRH receptor. Mutation of Arg38(1.35) to alanine resulted in 989- and 1268-fold reduction in affinity for GnRH I and GnRH II, respectively, the two endogenous ligands. Conservative mutation of Arg38(1.35) to lysine had less effect, giving reduced affinities of GnRH I and GnRH II by 24- and 54-fold, respectively. To test whether Arg38(1.35) interacts with the C-terminal Gly10-NH2 of GnRH, binding of GnRH analogs with substitution of the C-terminal glycinamide with ethylamide ([Pro9-NHEt]GnRH) was studied with wild-type and Arg38(1.35) mutant receptors. Mutation of Arg38(1.35) to lysine or alanine had much smaller effect on receptor affinity for [Pro9-NHEt]GnRH analogs and no effect on binding affinity of peptide antagonist cetrorelix. In parallel with the decreased affinity, the mutants also gave a decreased potency to GnRH-elicited inositol phosphate (IP) responses. The mutant receptors had effects on [Pro9-NHEt]GnRH-elicited IP responses similar to that of the parent GnRHs. These findings indicate that Arg38(1.35) of the GnRH receptor is essential for high-affinity binding of GnRH agonists and stabilizing the receptor active conformation. The mutagenesis results support the prediction of molecular modeling that Arg38(1.35) interacts with the C-terminal glycinamide and probably forms hydrogen bonds with the backbone carbonyl of Pro9 and Gly10-NH2.</p

    Identification of a Novel Ligand Binding Residue Arg 38(1.35)

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