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Search Results: 1 - 10 of 45589 matches for " Jan van Gijn "
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Is clopidogrel superior to aspirin in secondary prevention of vascular disease?
Ale Algra, Jan van Gijn
Trials , 2000, DOI: 10.1186/cvm-1-3-143
Abstract: A nice bottle of Graves arrived at our offices in early August 2000. The Dutch branch of Sanofi-Synthelabo sent this wine to collaborators of the Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events (CAPRIE) trial [1] to celebrate the regulation of reimbursement for clopidogrel in the Netherlands on 26 July. The official indication for this novel antiplatelet drug reads: 'secondary prevention in patients with atherosclerotic disease and proven aspirin sensitivity'. Sanofi-Synthelabo appealed against the limitation to patients intolerant to aspirin, but lost the lawsuit [2].What is the background of this legal quarrel? The cornerstone is clinical evidence from the CAPRIE trial, a ran-domised, blinded, international study [1]. Clopidogrel (75 mg daily) and aspirin (325 mg daily) were compared in the prevention of the composite outcome event 'vascular death, nonfatal stroke or nonfatal myocardial infarction'. Clopidogrel reduced the annual risk of such a vascular event from 5.83 to 5.32% in comparison with aspirin, corresponding to a relative risk reduction (RRR) of 8.7%. The 95% confidence interval just kept clear of the neutral value and ranged from 0.3 to 16.5%. The design of the study was based on the paradigm prevalent in the early 1990s: all clinical presentations of atherosclerotic disease should be regarded as different manifestations of a single disorder of the arterial vascular tree. The data of the CAPRIE trial do not necessarily support this paradigm, because the RRR values of the three diagnostic strata (each with over 6000 patients) differed considerably: -3.7% for myocardial infarction, +7.3% for ischaemic stroke, and 23.8% for peripheral arterial disease (P = 0.042). A similar difference between different categories of atherosclerotic disease had been observed by the AntiPlatelet Trialists' Collaboration [3]. The RRR values achieved by aspirin (compared with placebo) ranged from 18% for cerebral ischaemia to 35% for unstable angina.Clopido
Correction: PAIS: paracetamol (acetaminophen) in stroke; protocol for a randomized, double blind clinical trial. [ISCRTN74418480]
Heleen M den Hertog, H Bart Worp, H Maarten A van Gemert, Ale Algra, L Jaap Kappelle, Jan van Gijn, Peter J Koudstaal, Diederik WJ Dippel, the PAIS investigators
BMC Cardiovascular Disorders , 2008, DOI: 10.1186/1471-2261-8-29
Abstract: The previously planned statistical analysis based on a dichotomization of the scores on the modified Rankin Scale (mRS) may not make the most efficient use of the available baseline information. Therefore, the planned primary analysis of the PAIS study has been changed from fixed dichotomization of the mRS to a sliding dichotomy analysis.Instead of taking a single definition of good outcome for all patients, the definition is tailored to each individual patient's baseline prognosis on entry into the trial.The protocol change was initiated because of both advances in statistical approaches and to increase the efficiency of the trial by improving statistical power.Current Controlled Trials [ISCRTN74418480]The Paracetamol (Acetaminophen) In Stroke (PAIS) Study is a phase III multicenter, double blind, randomized, placebo-controlled clinical trial of high-dose acetaminophen in patients with acute stroke. The trial compares treatment with a daily dose of 6 g acetaminophen, started within 12 hours after the onset of symptoms, with matched placebo. The purpose of this study is to assess whether treatment with acetaminophen for 3 days will result in improved long-term functional outcome through a modest reduction in body temperature and prevention of fever [1].In the original protocol, the primary outcome measure is a dichotomized score on the modified Rankin Scale (mRS) [2] assessed at 3 months from onset of symptoms, with good functional outcome defined as a score of 0–2 and poor functional outcome as a score of 3-death.The common approach of dichotomizing the mRS, an ordinal outcome scale, has several disadvantages. First, it may not correspond with everyday clinical practice. Dichotomized outcome analyses convert ordinal scales into binary outcome measures. Most treatment strategies tested in acute stroke trials are not expected to be completely curative, but to lead to improvement. Therefore, it is also informative to show that treatment moves patients from severe to m
Hemicraniectomy after middle cerebral artery infarction with life-threatening Edema trial (HAMLET). Protocol for a randomised controlled trial of decompressive surgery in space-occupying hemispheric infarction
Jeannette Hofmeijer, G Johan Amelink, Ale Algra, Jan van Gijn, Malcolm R Macleod, L Jaap Kappelle, H Bart van der Worp, the HAMLET investigators
Trials , 2006, DOI: 10.1186/1745-6215-7-29
Abstract: The study design is that of a multi-centre, randomised clinical trial, which will include 112 patients aged between 18 and 60 years with a large hemispheric infarct with space-occupying oedema that leads to a decrease in consciousness. Patients will be randomised to receive either decompressive surgery in combination with medical treatment or best medical treatment alone. Randomisation will be stratified for the intended mode of conservative treatment (intensive care or stroke unit care). The primary outcome measure will be functional outcome, as determined by the score on the modified Rankin Scale, at one year.Large cerebral infarcts are commonly associated with variable degrees of brain oedema. In severe cases, this may lead to transtentorial or uncal herniation. Serious oedema formation usually manifests itself between the second and fifth day after stroke onset [1-4]. Brain tissue shifts rather than raised intracranial pressure (ICP) are probably the most likely cause of the initial decrease in consciousness [4,5].Fatal space-occupying brain oedema is rare, and occurs in 1 to 5% of patients with a supratentorial infarct [6,7]. However, in younger patients with ischaemic stroke, herniation accounts for about half of the deaths in the first month [8]. Patients with a hemispheric infarct and massive space-occupying brain oedema have a poor prognosis: in recent intensive care (IC)-based prospective series, the case fatality rate was about 80%, despite maximal conservative therapy [9,10].Several conservative treatment strategies have been proposed to limit brain tissue shifts and reduce intracranial pressure, such as sedation with barbiturates or propofol, hyperventilation, and osmotic therapy with glycerol, mannitol, or hypertonic saline hydroxyethyl starch (HES) [11-13]. However, no trials have addressed the efficacy of these therapies to improve clinical outcome [14], and several reports suggest that these are ineffective [9,10,15] or even detrimental [16,17]. The
PAIS: paracetamol (acetaminophen) in stroke; protocol for a randomized, double blind clinical trial. [ISCRTN 74418480]
Eric J van Breda, H Bart van der Worp, H Maarten A van Gemert, Ale Algra, L Jaap Kappelle, Jan van Gijn, Peter J Koudstaal, Diederik WJ Dippel, the PAIS investigators
BMC Cardiovascular Disorders , 2005, DOI: 10.1186/1471-2261-5-24
Abstract: Paracetamol (Acetaminophen) In Stroke (PAIS) is a randomized, double-blind clinical trial, comparing high-dose acetaminophen with placebo in 2500 patients. Inclusion criteria are a clinical diagnosis of hemorrhagic or ischemic stroke and the possibility to start treatment within 12 hours from onset of symptoms. The study will have a power of 86% to detect an absolute difference of 6% in the risk of death or dependency at three months, and a power of 72% to detect an absolute difference of 5%, at a 5% significance level.This is a simple trial, with a drug that only has a small effect on body temperature in normothermic patients. However, when lowering body temperature with acetaminophen does have the expected effectiveness, 20 patients will have to be treated to prevent dependency or death in one.In patients with acute stroke, increased body temperature is associated with high case fatality and poor functional outcome [1]. In the observational Copenhagen Stroke study, a 1°C increase in body temperature measured within 12 hours after stroke onset doubled the odds of poor outcome. The relation between body temperature and outcome was not affected by severity of symptoms at admission, lesion volume, or stroke type [1-6]. This suggests that even a small reduction in body temperature in acute stroke could improve outcome.We conducted two randomized, placebo-controlled clinical trials to study whether early treatment with acetaminophen reduces body temperature in patients with acute ischemic stroke confined to the carotid territory. In the first trial, seventy-six patients were randomized to daily treatment with either 3000 or 6000 mg acetaminophen, or placebo. In the high-dose group this resulted in a 0.4°C (95% CI: 0.1 to 0.7°C) lower body temperature than placebo treatment at 24 hours after onset [7]. The second trial was conducted to study the effect of ibuprofen and to confirm the effect of high-dose acetaminophen on body temperature. Seventy-five patients with acute
Quality assurance through outcome registration in colorectal cancer: An ECCO initiative for Europe
Van Gijn W.,Van de Velde C.J.H.
Acta Chirurgica Iugoslavica , 2010, DOI: 10.2298/aci1003017v
Abstract: In recent years there have been significant improvements in outcome of rectal cancer treatment. Both new surgical techniques as well as effective neoadjuvant treatment regimens have contributed to these improvements. It is key to spread these advances towards every rectal cancer patient and to make sure that not only patients who are treated within the framework of clinical trials may benefit from these advancements. Throughout Europe there have been interesting quality programs that have proved to facilitate the spread of up to date knowledge and skills among medical professionals resulting in improved treatment outcome. Nevertheless, between European countries remain differences in outcome and treatment schedules that cannot be easily explained. The European CanCer Organisation (ECCO) has recognised these importances's and created the 'European Registration of Cancer Care' (EURECCA) framework to develop a European colorectal audit structure. EURECCA will advance future treatment improvements and spread these to all European cancer patients. It provides opportunities to treat elderly and comorbid patients evidence based while it offers an unique insight in social-economical healthcare matters. As such, ECCO has established the basis for a strong, multidisciplinary audit structure with the commitment to improve cancer care for every European cancer patient.
A Clark-Ocone formula in UMD Banach spaces
Jan Maas,Jan van Neerven
Mathematics , 2007,
Abstract: Let H be a separable real Hilbert space and let F = (F_t)_{t\in [0,T]} be the augmented filtration generated by an H-cylindrical Brownian motion W_H on [0,T]. We prove that if E is a UMD Banach space, 1\leq p<\infty, and f\in D^{1,p}(E) is F_T-measurable, then f = \E f + \int_0^T P_F(Df) dW_H where D is the Malliavin derivative and P_F is the projection onto the F-adapted elements in a suitable Banach space of L^p-stochastically integrable L(H,E)-valued processes.
Boundedness of Riesz transforms for elliptic operators on abstract Wiener spaces
Jan Maas,Jan van Neerven
Mathematics , 2008,
Abstract: Let (E,H,mu) be an abstract Wiener space and let D_V := VD, where D denotes the Malliavin derivative and V is a closed and densely defined operator from H into another Hilbert space G. Given a bounded operator B on G, coercive on the closure of the range of V, we consider the realisation of the operator D_V* B D_V in L^p(E,mu) for 1
Gradient estimates and domain identification for analytic Ornstein-Uhlenbeck operators
Jan Maas,Jan van Neerven
Mathematics , 2009,
Abstract: Let (P(t)) be the Ornstein-Uhlenbeck semigroup associated with the stochastic Cauchy problem dU(t) = AU(t)dt + dW_H(t), where A is the generator of a C_0-semigroup (S(t)) on a Banach space E, H is a Hilbert subspace of E, and (W_H(t)) is an H-cylindrical Brownian motion. Assuming that (S(t)) restricts to a C_0-semigroup on H, we obtain L^p-bounds for the gradient D_H P(t). We show that if (P(t)) is analytic, then the invariance assumption is fulfilled. As an application we determine the L^p-domain of the generator of (P(t)) explicitly in the case where (S(t)) restricts to a C_0-semigroup on H which is similar to an analytic contraction semigroup. The results are applied to the 1D stochastic heat equation driven by additive space-time white noise.
Impact of the WFD on agriculture in the Netherlands and possible effect-specific hydrological measures: the Dutch approach
Jan van Bakel
Journal of Water and Land Development , 2006, DOI: 10.2478/v10025-007-0004-8
Abstract: The European Water Framework Directive can have enormous consequences for agriculture in the Netherlands. In parts of the country agriculture should be taken out of production because the nutrient loads to the surface water system are far too high. This doom scenario is of course undesired and a number of source-specific and effect-specific measures are necessary. The fate of nutrients in the soil is strongly interrelated with its hydrology. Directly, because nutrients are transported by water and the distribution of the residence time of drainage water is a good measure for the time behaviour of the nutrient loads to the surface water system. Longer residence time in the soil means more of nutrients applied by farmers but also a longer recovery period, after applying source-specific measures. In this paper three promising effect-specific hydrological measures are described buffer strips, retention strips, and controlled drainage.
Inova ní politika na regionální úrovni
Jan Van ura
Ergo , 2011, DOI: 10.2478/v10217-011-0004-5
Abstract: The possibility of regions in creating their own regional innovation policy largely depends on their position in the national governance system, their competences and available funds. Conditions for creating an effective innovation system at regional level also depends on other factors, particularly the willingness of regional governments to engage themselves in innovation policy. This article aims to assess the position of the Czech regions in developing their own innovation policy and way of its implementation. The first part of the article briefly introduces reader to approaches to implementation of innovation policy in several EU countries, and is followed by a comparison of Czech regions involvement in innovation policy according to the methodology of the Regional Innovation Monitor project.
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