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Biomedical subjects

Marcel Levi

Publications and source records attributed to Marcel Levi.

At least 19 recordsLinked to original sources

Plasma and plasma components in the management of disseminated intravascular coagulation.

A variety of clinical conditions can cause systemic activation of coagulation that ranges from insignificant laboratory changes to severe disseminated intravascular coagulation (DIC). DIC consists of a widespread systemic activation of coagulation, resulting in diffuse fibrin deposition in small and midsize vessels. There is compelling evidence from clinical and experimental studies that DIC is involved in the pathogenesis of microvascular dysfunction and contributes to organ failure. In addition, the massive and ongoing activation of coagulation can result in depletion of platelets and coagulation factors, which might cause bleeding. Recent insight into important pathogenetic mechanisms that might lead to DIC has resulted in novel preventive and therapeutic approaches to patients with sepsis and derangement of coagulation. Supportive strategies aimed at inhibition of coagulation activation might theoretically be justified and have been found beneficial in experimental and initial clinical studies. These strategies comprise inhibition of tissue factor-mediated activation of coagulation or restoration of physiological anticoagulant pathways.

Anticoagulants↗

Tissue factor in infection and severe inflammation.

In the pathogenesis of vascular disease, inflammation and coagulation play a pivotal role. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. Tissue factor (TF) plays an important role at the crossroad of coagulation and inflammation, as the principal initiator of coagulation and an important modulator of inflammation. Proinflammatory cytokines can induce TF expression on mononuclear cells and endothelial cells and thereby commence pathways that lead to thrombin generation. Simultaneously, TF may bind to cellular receptors, which may affect the production and release of inflammatory mediators. There is increasing experimental evidence that TF inhibition may have beneficial effects in disease states in which the combination of coagulation and inflammation plays a prominent role.

Blood Coagulation↗

Loss of endothelial glycocalyx during acute hyperglycemia coincides with endothelial dysfunction and coagulation activation in vivo.

Hyperglycemia is associated with increased susceptibility to atherothrombotic stimuli. The glycocalyx, a layer of proteoglycans covering the endothelium, is involved in the protective capacity of the vessel wall. We therefore evaluated whether hyperglycemia affects the glycocalyx, thereby increasing vascular vulnerability. The systemic glycocalyx volume was estimated by comparing the distribution volume of a glycocalyx permeable tracer (dextran 40) with that of a glycocalyx impermeable tracer (labeled erythrocytes) in 10 healthy male subjects. Measurements were performed in random order on five occasions: two control measurements, two measurements during normoinsulinemic hyperglycemia with or without N-acetylcysteine (NAC) infusion, and one during mannitol infusion. Glycocalyx measurements were reproducible (1.7 +/- 0.2 vs. 1.7 +/- 0.3 l). Hyperglycemia reduced glycocalyx volume (to 0.8 +/- 0.2 l; P < 0.05), and NAC was able to prevent the reduction (1.4 +/- 0.2 l). Mannitol infusion had no effect on glycocalyx volume (1.6 +/- 0.1 l). Hyperglycemia resulted in endothelial dysfunction, increased plasma hyaluronan levels (from 70 +/- 6 to 112 +/- 16 ng/ml; P < 0.05) and coagulation activation (prothrombin activation fragment 1 + 2: from 0.4 +/- 0.1 to 1.1 +/- 0.2 nmol/l; d-dimer: from 0.27 +/- 0.1 to 0.55 +/- 0.2 g/l; P < 0.05). Taken together, these data indicate a potential role for glycocalyx perturbation in mediating vascular dysfunction during hyperglycemia.

Acetylcysteine↗

Antithrombin in sepsis revisited.

As the pivotal phase III randomized controlled clinical trial on antithrombin concentrate in patients with severe sepsis did not show a beneficial effect of antithrombin treatment on 28-day mortality, the interest in the potential use of this treatment modality in sepsis has diminished. However, recent data on the effect of antithrombin administration on coagulation in combination with recent analyses from the clinical trials that were aimed to restore physiological anticoagulant pathways in patients with sepsis may revitalize the interest in antithrombin concentrate for the treatment of severe sepsis.

Anticoagulants↗

Risk of thromboembolism and bleeding after general surgery in patients with atrial fibrillation.

We provide insight into the risk of perioperative thromboembolism and bleeding in patients who have atrial fibrillation, use anticoagulants, and undergo a surgical procedure. Ninety-four patients underwent 121 noncardiac operations during a mean follow-up of 29 months. There was a 3.6-fold increased risk for all bleeding complications within 1 month after surgery compared with the control period (95% confidence interval 1.05 to 12.0). No thromboembolic event occurred in the first month after surgery compared with 11 events in the remaining period (0.4% per month).

Aged↗

A phase I study of recombinant human C1 inhibitor in asymptomatic patients with hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) is a congenital disorder with recurrent attacks of localized swelling of submucosal tissue, subcutaneous tissue, or both caused by a deficiency of the plasma protein C1 inhibitor (C1 esterase inhibitor [C1INH]). OBJECTIVE: We sought to evaluate the effects of recombinant human C1INH (rhC1INH) isolated from the milk of transgenic rabbits in 12 asymptomatic patients with HAE. METHODS: rhC1INH was intravenously administered at doses of 6.25 to 100 U/kg on 2 occasions. RESULTS: rhC1INH appeared safe and was well tolerated. The course of functional C1INH in plasma showed a full initial recovery (dose-normalized maximum concentration of about 0.02 U/mL/U/kg) and a dose-dependent clearance of rhC1INH. After infusion of rhC1INH at 100 U/kg, a clearance of approximately 13 mL/min, a half-life of approximately 3 hours, and a volume of distribution of approximately 3 L were observed. Infusion at this dose led to functional C1INH levels in plasma of at least twice the normal level for about 2 hours and greater than 0.4 U/mL for about 9 hours. rhC1INH displayed dose-dependent biologic activity by increasing the C4 level, which was about 2-fold at 12 hours after rhC1INH at 100 U/kg, and decreasing levels of cleaved C4. CONCLUSION: The observed safety profile and biologic activity of rhC1INH warrants further clinical studies to assess its efficacy in treating HAE attacks.

Angioedema↗

Recombinant human activated protein C resets thrombin generation in patients with severe sepsis - a case control study.

INTRODUCTION: Recombinant human activated protein C (rhAPC) is the first drug for which a reduction of mortality in severe sepsis has been demonstrated. However, the mechanism by which this reduction in mortality is achieved is still not clearly defined. The aim of the present study was to evaluate the dynamics of the anticoagulant, anti-inflammatory and pro-fibrinolytic action of rhAPC in patients with severe sepsis, by comparing rhAPC-treated patients with case controls. METHODS: In this prospectively designed multicenter case control study, 12 patients who were participating in the ENHANCE study, an open-label study of rhAPC in severe sepsis, were treated intravenously with rhAPC at a constant rate of 24 microg/kg/h for a total of 96 h. Twelve controls with severe sepsis matching the inclusion criteria received standard therapy. The treatment was started within 48 h after the onset of organ failure. Blood samples were taken before the start of the infusion and at 4, 8, 24, 48, 96 and 168 h, for determination of parameters of coagulation and inflammation. RESULTS: Sepsis-induced thrombin generation as measured by thrombin-antithrombin complexes and prothrombin fragment F1+2, was reset by rhAPC within the first 8 h of infusion. The administration of rhAPC did not influence parameters of fibrinolysis and inflammation. There was no difference in outcome or occurrence of serious adverse events between the treatment group and the control group. CONCLUSION: Sepsis-induced thrombin generation in severely septic patients is reset by rhAPC within the first 8 h of infusion without influencing parameters of fibrinolysis and inflammation.

Analysis of Variance↗

Factors that predict outcome of intensive care treatment in very elderly patients: a review.

INTRODUCTION: Advanced age is thought to be associated with increased mortality in critically ill patients. This report reviews available data on factors that determine outcome, on the value of prognostic models, and on preferences regarding life-sustaining treatments in (very) elderly intensive care unit (ICU) patients. METHODS: We searched the Medline database (January 1966 to January 2005) for English language articles. Selected articles were cross-checked for other relevant publications. RESULTS: Mortality rates are higher in elderly ICU patients than in younger patients. However, it is not age per se but associated factors, such as severity of illness and premorbid functional status, that appear to be responsible for the poorer prognosis. Patients' preferences regarding life-sustaining treatments are importantly influenced by the likelihood of a beneficial outcome. Commonly used prognostic models have not been calibrated for use in the very elderly. Furthermore, they do not address long-term survival and functional outcome. CONCLUSION: We advocate the development of new prognostic models, validated in elderly ICU patients, that predict not only survival but also functional and cognitive status after discharge. Such a model may support informed decision making with respect to patients' preferences.

Activities of Daily Living↗

Activation of inflammation and coagulation after infusion of C-reactive protein in humans.

C-reactive protein (CRP) has been postulated to play a causal part in atherosclerosis and its acute complications. We assessed the effects of CRP-infusion on coagulation and inflammatory pathways to determine its role in atherothrombotic disease. Seven male volunteers received an infusion on two occasions, containing 1.25 mg/kg recombinant human CRP (rhCRP) or diluent, respectively. CRP-concentrations rose after rhCRP-infusion from 1.9 (0.3 to 8.5) to 23.9 (20.5 to 28.1) mg/L, and subsequently both inflammation and coagulation were activated. This sequence of events suggests that CRP is not only a well known marker of cardiovascular disease, but is also probably a mediator of atherothrombotic disease.

Adult↗

Activated protein C inhibits local coagulation after intrapulmonary delivery of endotoxin in humans.

RATIONALE: Acute lung injury and pneumonia are associated with pulmonary activation of coagulation and suppression of fibrinolysis, resulting in fibrin deposition in the lung. Activated protein C (APC) has systemic anticoagulant effects in patients with sepsis. OBJECTIVE: To determine the effect of systemic administration of recombinant human APC on endotoxin-induced hemostatic alterations in the bronchoalveolar space in humans. METHODS: Healthy humans received intravenous APC (24 microg/kg/hour; n = 8) or vehicle (n = 7); all subjects were administered saline in one lung subsegment and endotoxin (4 ng/kg) into the contralateral lung. Bronchoalveolar lavage was performed 16 hours after saline and endotoxin administration. MEASUREMENTS AND MAIN RESULTS: Endotoxin induced local activation of coagulation, as reflected by elevated levels of thrombin-antithrombin complexes (1.9 +/- 0.1 ng/ml) and soluble tissue factor (15.0 +/- 0.6 pg/ml) in bronchoalveolar lavage fluid, which was inhibited by APC (1.4 +/- 0.1 ng/ml and 12.3 +/- 0.4 pg/ml, respectively; both p < 0.01). Concurrently, endotoxin suppressed fibrinolysis, as indicated by reduced bronchoalveolar levels of plasminogen activator activity accompanied by elevated levels of plasminogen activator inhibitor type I activity. APC diminished the rise in plasminogen activator inhibitor type I activity (from 3.9 +/- 0.1 to 3.0 +/- 0.2 ng/ml, p = 0.002), while not significantly influencing plasminogen activator activity levels. Endotoxin reduced bronchoalveolar protein C concentrations, which was prevented by APC. Protein C did not influence the endotoxin-induced rise in local soluble thrombomodulin levels. CONCLUSION: APC exerts an anticoagulant effect in the human lung challenged with endotoxin.

Blood Coagulation↗

Disseminated intravascular coagulation: What's new?

Disseminated intravascular coagulation (DIC) is a syndrome characterized by a systemic activation of coagulation leading to the intravascular deposition of fibrin in the (micro) vasculature and the simultaneous consumption of coagulation factors and platelets. The occurrence of microvascular thrombosis as a consequence of DIC is underscored by pathological, experimental and clinical findings, demonstrating a link between DIC and organ dysfunction. Pathogenetic pathways that play a role in the development of DIC include tissue factor-dependent activation of coagulation, defective physiological anticoagulant pathways (such as the antithrombin system and the protein C system), and impaired fibrinolysis, caused by elevated levels of plasminogen activator inhibitor type 1. Novel therapeutic strategies are based on current insights into the pathogenesis of DIC, and include anticoagulant strategies (eg, directed at tissue factor) and strategies to restore physiological anticoagulant pathways (such as activated protein C concentrate).

Animals↗

New antithrombotics in the treatment of thromboembolic disease.

New insights into the in vivo function of the coagulation system have resulted in the development of new antithrombotic agents with a more specific point of impact and more reliable pharmacological properties. Inhibition of coagulation can be achieved by specific thrombin inhibitors (e.g. melagatran), agents specifically targeted at factor Xa (e.g. pentasaccharides), and by tissue factor/factor VIIa blockers (e.g. recombinant NAPc2). In some situations, these agents are more effective and safer than the antithrombotics currently used. However, the major difference may be that the newer generation of antithrombotics does not require repeated laboratory control and dose adjustment to obtain a stable level of anticoagulation; therefore, they are more suitable for application in clinical practice. In this overview, we will briefly discuss the various new compounds that have recently become available or that will be introduced into clinical medicine in the near future and their relative efficacy and safety in comparison to currently used antithrombotic agents.

Journal Article↗

Elevated plantar pressures in neuropathic diabetic patients with claw/hammer toe deformity.

Elevated plantar foot pressures during gait in diabetic patients with neuropathy have been suggested to result, among other factors, from the distal displacement of sub-metatarsal head (MTH) fat-pad cushions caused by to claw/hammer toe deformity. The purpose of this study was to quantitatively assess these associations. Thirteen neuropathic diabetic subjects with claw/hammer toe deformity, and 13 age- and gender-matched neuropathic diabetic controls without deformity, were examined. Dynamic barefoot plantar pressures were measured with an EMED pressure platform. Peak pressure and force-time integral for each of 11 foot regions were calculated. Degree of toe deformity and the ratio of sub-MTH to sub-phalangeal fat-pad thickness (indicating fat-pad displacement) were measured from sagittal plane magnetic resonance images of the foot. Peak pressures at the MTHs were significantly higher in the patients with toe deformity (mean 626 (SD 260)kPa) when compared with controls (mean 363 (SD 115) kPa, P<0.005). MTH peak pressure was significantly correlated with degree of toe deformity (r=-0.74) and with fat-pad displacement (r=-0.71) (P<0.001). The ratio of force-time integral in the toes and the MTHs (toe-loading index) was significantly lower in the group with deformity. These results show that claw/hammer toe deformity is associated with a distal-to-proximal transfer of load in the forefoot and elevated plantar pressures at the MTHs in neuropathic diabetic patients. Distal displacement of the plantar fat pad is suggested to be the underlying mechanism in this association. These conditions increase the risk for plantar ulceration in these patients.

Diabetic Foot↗

Struggle for implementation of new strategies in intensive care medicine: anticoagulation, insulin, and lower tidal volumes.

The management of intensive care patients have changed dramatically in the last years: from merely supportive care, it has moved to evidence-based strategies that have been demonstrated to reduce mortality of the severely ill patients. Clinical research have brought numerous positive clinical trials offering intensive care physicians specific therapies to improve outcome of intensive care patients. Among them were the trials that tested the infusion of activated protein C in patients with severe sepsis, tight glycemic control in surgical intensive care patients, and use of lung protective mechanical ventilation by using small tidal volumes in patients with acute lung injury. Although results of these trials were sufficiently strong to, at least, consider implementation of these strategies in critical care medicine, published and yet unpublished reports show that there is significant struggle with implementation of these therapies. This manuscript focuses on the potential reasons that underlie this problem.

Anticoagulants↗

Two-way interactions between inflammation and coagulation.

Activation of inflammatory and coagulation pathways is important in the pathogenesis of vascular disease. There is ample evidence that extensive cross-talk between these two systems exists, whereby inflammation not only leads to activation of coagulation, but coagulation also markedly affects inflammatory activity. The main interfaces linking coagulation and inflammation are the tissue factor pathway, thrombin, the protein C system and the fibrinolytic (or plasminogen-plasmin) system. Proinflammatory cytokines and chemokines can affect all these coagulation mechanisms, and vice versa, activated coagulation proteases and physiological anticoagulants or components of the plasminogen-plasmin system can modulate inflammation by specific cell receptors. The intricate relationship between inflammation and coagulation may not only be relevant for vascular thrombotic disease but also has major consequences in the pathogenesis of microvascular failure and subsequent multiple organ failure in the setting of severe infection. This review focuses on the present understanding of the bidirectional relationship between inflammation and coagulation.

Antigens↗