Publications by authors named "Bart Ramakers"

Background: Physical restraints remain to be commonly used in agitated intensive care unit (ICU) patients worldwide, despite a lack of evidence on efficacy and safety and reports of detrimental short and long-term consequences, such as prolonged delirium and a longer ICU length of stay. Physical restraint minimization approaches have focused mainly on educational strategies and other non-pharmacological interventions. Combining these interventions with goal-directed light sedation therapy if needed may play an important contributory role in further reducing the use of physical restraints.

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Background: The Waterhouse-Friderichsen syndrome (WFS) is a serious illness associated with a high mortality rate and characterized by septic shock and signs of adrenocortical insufficiency.

Case Description: A 33-year-old male was seen in the emergency department with severe abdominal and back pain with diffuse mottled skin and rapidly progressive petechiae all over his body. Laboratory results showed severe lactate acidosis with renal dysfunction and indications of diffuse intravascular coagulation.

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Introduction: Adenosine exerts anti-inflammatory and tissue-protective effects during systemic inflammation. While the tissue-protective effects might limit organ damage, its anti-inflammatory properties may induce immunoparalysis and impede bacterial clearance. The common 34C>T loss-of-function variant of AMPD1 (rs17602729) is associated with increased adenosine formation, but effects on immune function and outcome in sepsis patients are unknown.

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Background: Over the past few years there has been an increase in the use of ecstasy among the Dutch population. A number of complications are associated with this drug, hyperthermia being the most well-known. A less commonly-occurring complication is pneumomediastinum.

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Leptospirosis is a zoonosis caused by pathogenic Leptospira species. Leptospira infection can range from subclinical to life-threatening disease. Renal failure and severe respiratory symptoms may occur and are associated with a high mortality rate.

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Although endothelial dysfunction is central to the pathogenesis of sepsis, no specific and clinically applicable marker for endothelial dysfunction is currently available. Endocan, a proteoglycan excreted by endothelial cells in response to inflammatory cytokines, may serve as such a marker. Our objective was to investigate the kinetics of endocan and its relationship with inflammation-induced endothelial dysfunction during experimental human endotoxemia.

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A higher body mass index (BMI) appears to be associated with lower mortality in critically ill patients, possibly explained by an altered innate immune response. However, the precise relationship between BMI and the innate immune response in humans in vivo is unknown. We investigated the relationship between BMI and the systemic cytokine response during experimental human endotoxemia.

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Objective: An overzealous inflammatory response is an important cause of morbidity and mortality in surgical, trauma, and critically ill patients. Enteral administration of lipid-rich nutrition was previously shown to attenuate inflammation and reduce organ damage via a cholecystokinin-1 receptor-mediated vagovagal reflex in animal studies. The current preclinical study investigates the immunomodulatory potential of a custom-made enteral nutrition during systemic inflammation in man.

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Patients with sepsis in the intensive care unit (ICU) are prone to develop Candida infections. Here, we investigated Candida-induced T-helper 17 (Th17) responses during experimental human endotoxemia and in patients with sepsis admitted to the ICU. Peripheral blood mononuclear cells were stimulated with Candida albicans.

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Objective: Adenosine modulates inflammation and prevents associated organ injury by activation of its receptors. During sepsis, the extracellular adenosine concentration increases rapidly, but the underlying mechanism in humans is unknown. We aimed to determine the changes in adenosine metabolism and signaling both in vivo during experimental human endotoxemia and in vitro.

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Introduction: In animal models of systemic inflammation, the endogenous nucleoside adenosine controls inflammation and prevents organ injury. Dipyridamole blocks the cellular uptake of endogenous adenosine and increases the extracellular adenosine concentration. We studied the effects of oral dipyridamole treatment on innate immunity and organ injury during human experimental endotoxemia.

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In the past decades, increased concentrations of the signaling molecule adenosine have been shown to play an important role in the prevention of tissue damage evoked by several stressful circumstances. During systemic inflammation, the circulating adenosine concentration increases rapidly, even up to 10-fold in septic shock patients. By binding to specific adenosine receptor subtypes, designated A1, A2a, A2b, and A3, adenosine exerts a wide variety of immunomodulating and (cyto)protective effects.

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Objectives: Endotoxin (lipopolysaccharide) tolerance is characterized by a transient refractory state to a subsequent lipopolysaccharide challenge. Following human endotoxemia, ex vivo tolerance of circulating leukocytes to lipopolysaccharide resolves within 24 hrs. However, the duration of in vivo tolerance, assumed to be primarily mediated by tissue-resident macrophages, is unknown.

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The autonomic nervous system and the inflammatory response are intimately linked. Heart rate variability (HRV) analysis is a widely used method to assess cardiac autonomic nervous system activity, and changes in HRV indices may correlate with inflammatory markers. Here, we investigated whether baseline HRV predicts the acute inflammatory response to endotoxin.

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Introduction: Preclinical studies have shown that the endogenous nucleoside adenosine prevents excessive tissue injury during systemic inflammation. We aimed to study whether endogenous adenosine also limits tissue injury in a human in vivo model of systemic inflammation. In addition, we studied whether subjects with the common 34C > T nonsense variant (rs17602729) of adenosine monophosphate deaminase (AMPD1), which predicts increased adenosine formation, have less inflammation-induced injury.

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Introduction: Effects of systemic inflammation on cerebral function are not clear, as both inflammation-induced encephalopathy as well as stress-hormone mediated alertness have been described.

Methods: Experimental endotoxemia (2 ng/kg Escherichia coli lipopolysaccharide [LPS]) was induced in 15 subjects, whereas 10 served as controls. Cytokines (TNF-alpha, IL-6, IL1-RA and IL-10), cortisol, brain specific proteins (BSP), electroencephalography (EEG) and cognitive function tests (CFTs) were determined.

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Neutrophils play an important role in host defense. However, deregulation of neutrophils contributes to tissue damage in severe systemic inflammation. In contrast to complications mediated by an overactive neutrophil compartment, severe systemic inflammation is a risk factor for development of immune suppression and as a result, infectious complications.

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Adequate responses by our innate immune system toward invading pathogens were of vital importance for surviving infections, especially before the antibiotic era. Recently, a polymorphism in Mal (Ser180Leu, TIRAP rs8177374), an important adaptor protein downstream of the Toll-like receptor (TLR) 2 and 4 pathways, has been described to provide protection against a broad range of infectious pathogens. We assessed the functional effects of this polymorphism in human experimental endotoxemia, and we demonstrate that individuals bearing the TIRAP 180L allele display an increased, innate immune response to TLR4 and TLR2 ligands, but not to TLR9 stimulation.

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Because severe sepsis is frequently complicated by multiple organ failure, it is of importance to monitor organ function. Unfortunately, conventional liver function markers are either relatively unspecific or have a long half-life, which make them poor predictors of acute liver injury. Glutathione S-transferase A1-1 (GSTA1-1) has a relatively short half-life (1 h), is more specific, and is rapidly released into the blood after liver damage.

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In the present study, we determined whether the immunomodulatory effect of adenosine receptor stimulation depends on the Toll-like Receptor (TLR) used for stimulation of cytokine release. Therefore, human mononuclear cells were stimulated by different TLR agonists in the absence and presence of A1 (CPA), A2a (CGS21680), and A3 (Cl-IB-MECA) adenosine receptor agonists. Effects of these agonists on Il-6, Il-10, IFN-gamma, TNF-alpha, and Il-1beta production were expressed as percentage inhibition/stimulation after TLR stimulation.

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Objectives: We studied whether caffeine impairs protection by ischemic preconditioning (IP) in humans.

Background: Ischemic preconditioning is critically dependent on adenosine receptor stimulation. We hypothesize that the adenosine receptor antagonist caffeine blocks the protective effect of IP.

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Background: Adenosine receptor stimulation induces several effects that could limit ischemia-reperfusion injury. We hypothesize that treatment with the nucleoside uptake inhibitor dipyridamole increases endogenous adenosine and limits ischemia-reperfusion injury in humans.

Methods: Ischemia-reperfusion injury was studied in forearm skeletal muscle by technetium Tc 99m-labeled annexin A5 scintigraphy.

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