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Muzaffar S, Shukla N, Angelini GD, Jeremy JY. Prednisolone augments superoxide formation in porcine pulmonary artery endothelial cells through differential effects on the expression of nitric oxide synthase and NADPH oxidase. Br J Pharmacol 2005; 145:688-97. [PMID: 15852033 PMCID: PMC1576183 DOI: 10.1038/sj.bjp.0706235] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Accepted: 03/18/2005] [Indexed: 12/15/2022] Open
Abstract
1. Prednisolone, a potent anti-inflammatory drug, has proved ineffective in treating acute respiratory distress syndrome (ARDS). ARDS is associated with superoxide (O(2)(*-)) generation, which negates nitric oxide (NO). NO also downregulates NADPH oxidase and inhibits O(2)(*-) formation. A possible reason for the lack of effect of prednisolone may due to an inhibition of eNOS expression. In order to test this proposal, the effect of prednisolone on O(2)(*-) formation and the expression of gp91(phox) (catalytic subunit of NADPH oxidase) and eNOS in pig pulmonary artery (PA) segments and PA endothelial cells (PAECs) and PA vascular smooth muscle cells (PAVSMCs) was investigated. 2. PA segments and cells were incubated with prednisolone and tumour necrosis factor-alpha (TNF-alpha) for 16 h. O(2)(*-) formation was measured spectrophometrically and gp91(phox) and eNOS expression by Western blotting. The role of the NO-cGMP axis was studied using morpholinosydnonimine hydrochloride, the diethylamine/NO complex (DETA-NONOate), the guanylyl cyclase inhibitor, 1H-{1,2,4}oxadiazolo{4,3-a}quinoxalin-1-one (ODQ) and the stable cGMP analogues, 8-bromo cGMP and 8-(4-chlorophenylthio)-cGMP (8-pCPT-cGMP). NO release was studied using a fluorescence assay and O(2)(*-)-NO interactions with a nitrite/nitrate assay. 3. Prednisolone elicited significant increase in O(2)(*-) formation in intact PA segments and PAECs, but not PAVSMCs, in a concentration-dependent manner. In endothelium-denuded segments, prednisolone slightly enhanced O(2)(*-) release. TNF-alpha further increased prednisolone-enhanced O(2)(*-) formation in intact PA segments and PAECs. NADPH oxidase inhibitor, apocynin, inhibited O(2)(*-) formation. Increased O(2)(*-) release and gp91(phox) expression in PAECs elicited by prednisolone was blocked by SIN-1 (3-morpholinosydnonimine hydrochloride), DETA-NONOate, 8-pCPT-cGMP and 8-bromo cGMP. The effects of SIN-1 on gp91(phox) expression were reversed by ODQ. Finally, eNOS protein expression was significantly reduced by prednisolone. 4. Prednisolone increases O(2)(*-) in porcine PAECs through a downregulation of endogenous eNOS expression. Since the NO-cGMP axis inhibits gp91(phox) expression, the resultant decrease in endogenous NO formation then augments NADPH oxidase activity, which in turn results in increased O(2)(*-) formation. Since O(2)(*-) promotes inflammation, this mechanism may explain why prednisolone is ineffective in treating ARDS. Therapeutically, the coadministration of an NO donor may render prednisolone more effective in treating ARDS.
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Affiliation(s)
- Saima Muzaffar
- Department of Cardiac Surgery, Bristol Heart Institute, Bristol Royal Infirmary, University of Bristol, Bristol
| | - Nilima Shukla
- Department of Cardiac Surgery, Bristol Heart Institute, Bristol Royal Infirmary, University of Bristol, Bristol
| | - Gianni D Angelini
- Department of Cardiac Surgery, Bristol Heart Institute, Bristol Royal Infirmary, University of Bristol, Bristol
| | - Jamie Y Jeremy
- Department of Cardiac Surgery, Bristol Heart Institute, Bristol Royal Infirmary, University of Bristol, Bristol
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552
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Carnio EC, Stabile AM, Batalhão ME, Silva JS, Antunes-Rodrigues J, Branco LGS, Magder S. Vasopressin release during endotoxaemic shock in mice lacking inducible nitric oxide synthase. Pflugers Arch 2005; 450:390-4. [PMID: 15971084 DOI: 10.1007/s00424-005-1400-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Accepted: 02/16/2005] [Indexed: 11/30/2022]
Abstract
We tested the hypothesis that nitric oxide (NO) arising from the action of inducible nitric oxide synthase (iNOS) is responsible for the deficiency in vasopressin (AVP) release and consequent hypotension during endotoxaemic shock. Wild-type (WT) and iNOS knockout mice (iNOS(-/-)) were given either saline or Escherichia coli lipopolysaccharide (LPS, 1.0 mg/kg i.v., final volume 0.03 ml). Mean arterial blood pressure (MAP) was measured and plasma AVP levels determined before and after LPS or saline injection. In WT mice, MAP was significantly lower 2 h after LPS administration and remained low for the remainder of the 6-h observation period. AVP plasma levels were increased at the 2nd and 4th h of the experiment, returning thereafter to basal levels. Conversely, LPS injection in iNOS iNOS(-/-) mice elicited a sustained increase in plasma AVP concentration and attenuated the fall in blood pressure. These data indicate that NO arising from the iNOS plays an important inhibitory role in AVP release during endotoxaemia and may be responsible for the hypotension occurring during this vasodilatory shock.
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Affiliation(s)
- Evelin C Carnio
- Escola de Enfermagem de Ribeirão Preto, Universidade de São Paulo, 14040-902-Ribeirão Preto, São Paulo, Brazil.
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553
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Siegemund M, van Bommel J, Schwarte LA, Studer W, Girard T, Marsch S, Radermacher P, Ince C. Inducible nitric oxide synthase inhibition improves intestinal microcirculatory oxygenation and CO2 balance during endotoxemia in pigs. Intensive Care Med 2005; 31:985-92. [PMID: 15959764 DOI: 10.1007/s00134-005-2664-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 05/04/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE We examined whether selective inhibition of inducible nitric oxide synthase (iNOS) promotes intestinal microvascular oxygenation (microPO2) and CO2 off-load after endotoxic shock. DESIGN AND SETTING Prospective, controlled experimental study in a university animal research laboratory. SUBJECTS 13 domestic pigs. INTERVENTIONS After baseline measurements shock was induced by 1 microg kg-1 h-1 endotoxin until mean arterial pressure fell below 60 mmHg. After 30 min in shock the animals were resuscitated with either fluid alone (control, n=6) or fluid and the iNOS inhibitor N-[3-(aminomethyl)benzyl]acetamidine hydrochloride (1400W, n=7). As final experimental intervention all animals received the nonselective NOS inhibitor L-NAME. MEASUREMENTS AND RESULTS Systemic and regional hemodynamic and oxygenation parameters were measured at baseline, during endotoxemia and shock, hourly for 3 h of 1400W therapy, and 30 min after the final L-NAME administration. microPO2 was assessed by the Pd-porphyrin phosphorescence technique, and the arterial to intestinal PCO2 gap was determined by air tonometry. Endotoxemia and shock resulted in a decrease in ileal mucosal and serosal microPO2 and a rise in PCO2 gap. The combination of 1400W and fluid resuscitation, but not fluid alone, normalized both the serosal microPO2 and the intestinal PCO2 gap. Administration of L-NAME decreased cardiac output and oxygen delivery and intestinal microPO2 and blood flow in both groups. CONCLUSIONS Partial blockade of NO production by 1400W increased serosal microvascular oxygenation and decreased the intestinal CO2 gap. This findings are consistent with the idea that 1400W corrects pathological flow distribution and regional dysoxia within the intestinal wall following endotoxic shock.
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Affiliation(s)
- Martin Siegemund
- Department of Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
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554
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555
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Foubister V. Looking for new sepsis targets. Drug Discov Today 2005; 10:680-1. [PMID: 15896678 DOI: 10.1016/s1359-6446(05)03436-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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556
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Ruokonen E, Pettilä V. Surviving Sepsis campaign--outcome of severe sepsis can be improved by revising procedural standards. Acta Anaesthesiol Scand 2005; 49:597-8. [PMID: 15836670 DOI: 10.1111/j.1399-6576.2005.00716.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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557
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Muzaffar S, Shukla N, Angelini GD, Jeremy JY. Acute hypoxia simultaneously induces the expression of gp91phox and endothelial nitric oxide synthase in the porcine pulmonary artery. Thorax 2005; 60:305-13. [PMID: 15790986 PMCID: PMC1747371 DOI: 10.1136/thx.2003.018796] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The effect of hypoxia on the formation of superoxide (O2-), the expression of gp91phox and endothelial NO synthase (eNOS) were studied in pig intact pulmonary artery (PA) segments and PA vascular smooth muscle cells (PAVSMCs) and PA endothelial cells (PAECs). METHODS Segments and cells were incubated under hypoxic conditions for 2 hours (with or without enzyme inhibitors) and the formation of O2- measured spectrophotometrically. Protein expression was assessed using Western blotting and immunocytochemistry. RESULTS Hypoxia promoted the formation of O2- in PA segments, PAVSMCs and PAECs, an effect inhibited by diphenylene iodonium and apocynin (NAD[P]H oxidase inhibitors). Hypoxia induced O2- formation was enhanced by inhibition of eNOS and augmented by endotoxin and cytokines and re-oxygenation. Hypoxia also promoted the expression of gp91phox and eNOS. In intact PA segments hypoxia induced the expression of nitrotyrosine and eNOS in the endothelium. CONCLUSIONS The simultaneous upregulation of NAD[P]H oxidase and eNOS in response to hypoxia in the PA results in the simultaneous formation of O2-, NO, and ONOO-. This may represent either a protective mechanism designed to counter the pro-oxidant effect of hypoxia or a novel pathological mechanism underlying the progression of acute respiratory distress syndrome (ARDS).
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Affiliation(s)
- S Muzaffar
- Bristol Heart Institute, Bristol Royal Infirmary, Bristol BS2 8HW, UK
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558
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559
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Beishuizen A, Hartemink KJ, Vermes I, Groeneveld AJ. Circulating cardiovascular markers and mediators in acute illness: an update. Clin Chim Acta 2005; 354:21-34. [PMID: 15748596 DOI: 10.1016/j.cccn.2004.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 11/02/2004] [Accepted: 11/05/2004] [Indexed: 11/27/2022]
Abstract
An update is given of the circulating markers and mediators of cardiovascular dysfunction in acute illness. Some of these circulating markers reflect mediator action on the peripheral vasculature, such as endothelium-derived endothelin and nitrite/nitritate, the stable end products of nitric oxide. Other markers mainly reflect actions on the heart, such as the natriuretic peptide family, released from the heart upon dilatation, serving as a marker of congestive heart failure and potentially having negative inotropic effects. Indeed, some factors may be both markers as well as mediators of cardiovascular dysfunction of the acutely ill and bear prognostic significance. Assessing circulating levels may help refine clinical judgment of the cardiovascular derangements encountered at the bedside, together with clinical signs and hemodynamic variables. For instance, assessing natriuretic peptides in patients with pulmonary edema of unclear origin may help to diagnose congestive heart failure and cardiogenic pulmonary edema, when the pulmonary capillary wedge pressure is not measured or inconclusive. Future aligning of hemodynamic abnormalities with patterns of circulating cardiovascular markers/mediators may help to stratify patients for inclusion in studies to assess the causes, response to therapy and prognosis of cardiovascular derangements in the acutely ill.
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Affiliation(s)
- Albertus Beishuizen
- Department of Intensive Care Unit, VU University Medical Center and Institute for Cardiovascular Research, De Boelelaan 1117 1081 HV Amsterdam, The Netherlands
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560
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561
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Siroen MPC, van Leeuwen PAM, Nijveldt RJ, Teerlink T, Wouters PJ, Van den Berghe G. Modulation of asymmetric dimethylarginine in critically ill patients receiving intensive insulin treatment: A possible explanation of reduced morbidity and mortality?*. Crit Care Med 2005; 33:504-10. [PMID: 15753739 DOI: 10.1097/01.ccm.0000155784.59297.50] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Asymmetric dimethylarginine, which inhibits production of nitric oxide, has been shown to be a strong and independent predictor of mortality in critically ill patients with clinical evidence of organ dysfunction. Interestingly, intensive insulin therapy in critically ill patients improved morbidity and mortality, but the exact mechanisms by which these beneficial effects are brought about remain unknown. Therefore, we aimed to investigate whether modulation of asymmetric dimethylarginine concentrations by intensive insulin therapy is involved in these effects. DESIGN A prospective, randomized, controlled trial. SETTING A 56-bed predominantly surgical intensive care unit in a tertiary teaching hospital. PATIENTS From a study of 1,548 critically ill patients who were randomized to receive either conventional or intensive insulin therapy, we included 79 patients who were admitted to the intensive care unit after complicated pulmonary and esophageal surgery and required prolonged (>/=7 days) intensive care. INTERVENTIONS Determination of asymmetric dimethylarginine concentrations. MEASUREMENTS AND MAIN RESULTS Asymmetric dimethylarginine concentrations were determined with high-performance liquid chromatography on the day of admission, on day 2, on day 7, and on the last day at the intensive care unit. Although the asymmetric dimethylarginine levels did not change between day 0 and day 2 in patients receiving intensive insulin treatment, there was a significant increase during this period in the conventionally treated patients (p = .043). Interestingly, the mean daily insulin dose was inversely associated with the asymmetric dimethylarginine concentration on the last day (r = -.23, p = .042), and the asymmetric dimethylarginine concentration on the last day at the intensive care unit was significantly lower in the intensive insulin treatment group (p = .048). Furthermore, asymmetric dimethylarginine was positively associated with duration of intensive care unit stay, duration of ventilatory support, duration of inotropic and vasopressor treatment, number of red cell transfusions, duration of antibiotic treatment, presence of critical illness polyneuropathy, mean Acute Physiology and Chronic Health Evaluation II score, and cumulative Therapeutic Intervention Scoring System-28 score. In addition, asymmetric dimethylarginine levels in patients who died were significantly higher compared with survivors, and changes in the course of asymmetric dimethylarginine plasma concentrations were predictive for adverse intensive care unit outcome. CONCLUSIONS Modulation of asymmetric dimethylarginine concentration by insulin at least partly explains the beneficial effects found in critically ill patients receiving intensive insulin therapy.
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Affiliation(s)
- Michiel P C Siroen
- Department of Surgery, VU University Medical Center, Amsterdam, The Netherlands
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562
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Brun-Buisson C. Les DSMB 2. De l’importance d’un DSMB efficace : exemples d’essais cliniques « à risque ». Med Sci (Paris) 2005; 21:187-9. [PMID: 15691491 DOI: 10.1051/medsci/2005212187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The DSMB (data safety and monitoring board) takes an increasing role in the monitoring of clinical trials, especially in large multicenter trials conducted in populations at high risk of morbidity or mortality. The DSMB is a an expert committee, independent from the investigators and the sponsor of the trial, which periodically examines the safety data accumulated during progress of the trial and ensures that the benefit/risk ratio remains acceptable for participating patients. A few examples, derived for recent experience of clinical trials conducted in acutely ill patients, illustrate the importance of an efficient and reactive DSMB to monitor patients' safety, especially during large multicenter trials.
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Affiliation(s)
- Christian Brun-Buisson
- Service de Réanimation médicale, CHU Henri Mondor, 51, avenue du Maréchal de Lattre de Tassigny, 94010 Créteil Cedex, France. christian.brun-buisson@ hmn.ap-hop-paris.fr
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563
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Frost MT, Wang Q, Moncada S, Singer M. Hypoxia accelerates nitric oxide-dependent inhibition of mitochondrial complex I in activated macrophages. Am J Physiol Regul Integr Comp Physiol 2005; 288:R394-400. [PMID: 15486095 DOI: 10.1152/ajpregu.00504.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Excess production of nitric oxide (NO) is implicated in the development of multiple organ failure, with a putative mechanism involving direct mitochondrial inhibition, predominantly affecting complex I. The persistent effects of NO on complex I may be mediated through S-nitrosylation and/or nitration. The temporal contribution of these chemical modifications to the inhibition of respiration and the influence of concurrent hypoxia have not been previously examined. We therefore addressed these questions using J774 macrophages activated by endotoxin and interferon-γ over a 24-h period, incubated at 21% and 1% oxygen. Oxygen consumption and complex I activity fell progressively over time in the activated cells. This was largely prevented by coincubation with the nonspecific NO synthase inhibitor l- N5-(1-iminoethyl)-ornithine. Addition of glutathione ethyl ester reversed the inhibition at initial time points, suggesting an early mechanism involving nitrosylation. Thereafter, the inhibition of complex I became more persistent, coinciding with a progressive increase in mitochondrial nitration. Hypoxia accelerated the persistent inhibition of complex I, despite a reduction in the total amount of NO generated. Our results suggest that hypoxia amplified the mitochondrial inhibition induced by NO generated during inflammatory disease states.
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Affiliation(s)
- Matthew T Frost
- Wolfson Institute for Biomedical Research, University College London, Gower St., London WC1E 6BT, UK
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564
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Stehr SN, Weber S, Heller SC, Weikel J, Hübler M, Koch T, Heller AR. N(omega)-nitro-L-arginine methyl ester effects on neutrophil function and bacterial clearance. Shock 2005; 22:180-5. [PMID: 15257093 DOI: 10.1097/01.shk.0000132487.89800.15] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nitric oxide synthase (NOS) inhibitors are considered promising as a therapeutic option in severe septic shock. The aim of this study was to investigate the effects of N-nitro-L-arginine methyl ester (L-NAME) application on neutrophil (PMN) respiratory burst, phagocytosis, and elimination of Escherichia coli from blood and tissue in rabbits. Twenty-eight female chinchilla rabbits were randomized to a treatment and control group. To quantify the bacterial clearance process, 10 colony forming units (CFU) of E. coli were injected intravenously into anesthetized rabbits. Animals in the L-NAME group had a significantly higher mortality compared with controls. NOS inhibition resulted in a significant delay of bacterial clearance (P < 0.001). These findings correlated with a significant augmentation of all organ E. coli findings (P = 0.002-0.035). PMN phagocytosis activity was notably reduced by L-NAME treatment during the experimental observation. Neutrophil burst, on the other hand, was amplified by NOS inhibition (P = 0.008). Our findings point to an interference with the PMN-dependent immune mechanisms after L-NAME treatment. The augmented PMN burst reaction could be a compensatory mechanism, potentially leading to tissue damage. Therefore, in this model, we find sufficient evidence pointing to a possible cause for the deleterious effect of early nonselective NOS inhibition in critically ill patients.
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Affiliation(s)
- Sebastian N Stehr
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany
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565
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Abstract
PURPOSE OF REVIEW Severe sepsis and septic shock are common and deadly conditions for which the epidemiology, pathogenesis, and management continue to evolve. Recent publications (2003 and early 2004) have been systematically reviewed for important new original research and scholarly reviews, with an emphasis on clinical advances in adults. RECENT FINDINGS Important new epidemiologic studies establish the increasing frequency (nearly 9% per year) and falling mortality rates associated with sepsis. Sepsis definitions were reviewed by a group of experts, and the principal features of the 1991 consensus conference definitions were supported, with a new framework for evaluation of sepsis proposed. New research and thoughtful reviews continue to elucidate the pathogenesis of sepsis, with emphasis on innate immunity and time-based changes in immune status, varying from hyperreactive immunity and inflammation to immune depression with enhanced risk for nosocomial infections. A comprehensive evidence-based approach to the management of severe sepsis is presented in an important document developed by representatives from many critical care and infectious disease societies. Management includes early targeted resuscitation, broad empiric antibiotic coverage and source control, effective shock evaluation and treatment, adjuvant therapy with recombinant human activated protein C and moderate-dose hydrocortisone in selected patients, and comprehensive supportive care. Recently published multicenter clinical trials for novel agents have been disappointing, particularly for a nitric oxide synthase inhibitor that effectively supported blood pressure but increased mortality. SUMMARY The works reviewed reflect the advances in the care of patients with sepsis.
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Affiliation(s)
- Curtis N Sessler
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Virginia Commonwealth University Health System, Richmond, Virginia, USA.
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566
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Abstract
Septic shock, the most severe complication of sepsis, is a deadly disease. In recent years, exciting advances have been made in the understanding of its pathophysiology and treatment. Pathogens, via their microbial-associated molecular patterns, trigger sequential intracellular events in immune cells, epithelium, endothelium, and the neuroendocrine system. Proinflammatory mediators that contribute to eradication of invading microorganisms are produced, and anti-inflammatory mediators control this response. The inflammatory response leads to damage to host tissue, and the anti-inflammatory response causes leucocyte reprogramming and changes in immune status. The time-window for interventions is short, and treatment must promptly control the source of infection and restore haemodynamic homoeostasis. Further research is needed to establish which fluids and vasopressors are best. Some patients with septic shock might benefit from drugs such as corticosteroids or activated protein C. Other therapeutic strategies are under investigation, including those that target late proinflammatory mediators, endothelium, or the neuroendocrine system.
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Affiliation(s)
- Djillali Annane
- Service de Réanimation, Hôpital Raymond Poincaré, Assistance Publique-Hôpitaux de Paris, Faculté de Médecine Paris Ile de France Ouest, Université de Versailles Saint Quentin en Yvelines, Garches, France.
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567
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Hauser B, Radermacher P, Thiemermann C, Matejovic M. NITRIC OXIDE, BACTERIA, AND HOST DEFENSE IN SEPSIS: WHO NEEDS WHAT? Shock 2004; 22:588-90. [PMID: 15545834 DOI: 10.1097/00024382-200412000-00016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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568
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Abstract
OBJECTIVE Sepsis is a major health problem considering its significant morbidity and mortality rate. The amino acid L-arginine has recently received substantial attention in relation to human sepsis. However, knowledge of arginine metabolism during sepsis is limited. Therefore, we reviewed the current knowledge about arginine metabolism in sepsis. DATA SOURCE This review summarizes the literature on arginine metabolism both in general and in relation to sepsis. Moreover, arginine-related therapies are reviewed and discussed, which includes therapies of both nitric oxide (NO) and arginine administration and therapies directed toward inhibition of NO. DATA In sepsis, protein breakdown is increased, which is a key process to maintain arginine delivery, because both endogenous de novo production from citrulline and food intake are reduced. Arginine catabolism, on the other hand, is markedly increased by enhanced use of arginine in the arginase and NO pathways. As a result, lowered plasma arginine levels are usually found. Clinical symptoms of sepsis that are related to changes in arginine metabolism are mainly related to hemodynamic alterations and diminished microcirculation. NO administration and arginine supplementation as a monotherapy demonstrated beneficial effects, whereas nonselective NO synthase inhibition seemed not to be beneficial, and selective NO synthase 2 inhibition was not beneficial overall. CONCLUSIONS Because sepsis has all the characteristics of an arginine-deficiency state, we hypothesise that arginine supplementation is a logical option in the treatment of sepsis. This is supported by substantial experimental and clinical data on NO donors and NO inhibitors. However, further evidence is required to prove our hypothesis.
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Affiliation(s)
- Yvette C Luiking
- Maastricht University/Hospital, Department of Surgery, Nutrition and Toxicology Research Institute, Maastricht, The Netherlands
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569
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Wang W, Mitra A, Poole B, Falk S, Lucia MS, Tayal S, Schrier R. Endothelial nitric oxide synthase-deficient mice exhibit increased susceptibility to endotoxin-induced acute renal failure. Am J Physiol Renal Physiol 2004; 287:F1044-8. [PMID: 15475535 DOI: 10.1152/ajprenal.00136.2004] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute renal failure (ARF) in septic patients drastically increases the mortality to 50-80%. Nitric oxide (NO) has been shown to be increased in sepsis. Endothelial nitric oxide synthase (eNOS) is one of the major regulators of arterial blood pressure and regional blood flow; however, its in vivo role in septic ARF is still unclear. We hypothesized that eNOS affords a protective effect against the renal vasoconstriction during endotoxemia. Because there are no specific inhibitors for eNOS, the study was therefore undertaken in eNOS knockout mice. There was no significant difference in baseline glomerular filtration rate (GFR) between the wild-type mice and the eNOS knockout mice (140 +/- 10 vs. 157 +/- 18 microl/min, n = 9, P = not significant). However, renal blood flow (RBF) was significantly decreased in eNOS knockout mice compared with the wild-type controls (0.62 +/- 0.05 ml/min, n = 6 vs. 0.98 +/- 0.13 ml/min, n = 8, P < 0.05). Mean arterial pressure (MAP) was significantly higher in eNOS knockout mice than the wild-type controls (109 +/- 5 vs. 80 +/- 1 mmHg, n = 10, P < 0.01). Thus renal vascular resistance (RVR) was much higher in eNOS knockout mice than in the wild-type mice (176 +/- 2, n = 6 vs. 82 +/- 1 mmHg.ml(-1).min(-1), n = 8, P < 0.01). When 1.0 mg/kg LPS was injected, there was no change in MAP in either the wild-type (84 +/- 3 mmHg, n = 10) or the eNOS knockout mice (105 +/- 5 mmHg, n = 10). Although GFR (154 +/- 22 microl/min, n = 8) and RBF (1.19 +/- 0.05 ml/min, n = 9) remained unchanged with the 1.0-mg/kg dose of LPS in the wild-type mice, GFR (83 +/- 18 vs. 140 +/- 10 microl/min, n = 6, P < 0.01) and RBF (0.36 +/- 0.04 vs. 0.62 +/- 0.05 ml/min, n = 6, P < 0.01) decreased significantly in the eNOS knockout mice. Fractional excretion of sodium increased significantly in eNOS knockout mice during endotoxemia (3.61 +/- 0.78, n = 7 vs. 0.95 +/- 0.14, n = 6, P < 0.01), whereas it remained unchanged in the wild-type mice (0.59 +/- 0.16, n = 9 vs. 0.42 +/- 0.05, n = 6, P = not significant). In summary, eNOS knockout mice have increased RVR and are more susceptible to endotoxemic ARF than wild-type mice despite higher MAP.
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Affiliation(s)
- Wei Wang
- Dept. of Medicine, Univ. of Colorado Health Sciences Center, 4200 East 9th Avenue, Box C-281, Denver, CO 80262, USA
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570
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Nijveldt RJ, Siroen MPC, Teerlink T, van Leeuwen PAM. Elimination of asymmetric dimethylarginine by the kidney and the liver: a link to the development of multiple organ failure? J Nutr 2004; 134:2848S-2852S; discussion 2853S. [PMID: 15465798 DOI: 10.1093/jn/134.10.2848s] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Asymmetric dimethylarginine (ADMA) is a recently recognized endogenous inhibitor of nitric oxide production. Its role in cardiovascular disease is emerging, and ADMA appears to be an important causal factor in dysfunction of the vascular system. Several studies show that ADMA accumulates during renal failure, and ADMA has been identified as causing the cardiovascular complications accompanying renal failure. In addition to the kidney, we recently suggested an important role for the liver as an ADMA-eliminating organ. In a population of critically ill patients, hepatic failure was the most prominent determinant of ADMA concentration, and, notably, high ADMA concentration proved to be a strong and independent risk factor for intensive care unit mortality in these patients. We here summarize the role of both the kidney and the liver in the regulation of ADMA levels. In addition, the potential central role of ADMA as a causative factor in the development of multiple organ failure is discussed.
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Affiliation(s)
- Robert J Nijveldt
- Department of Surgery, VU Univerity Medical Center, Amstredam, The Netherlands
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571
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Geppert A, Huber K. Inflammation and cardiovascular diseases: lessons that can be learned for the patient with cardiogenic shock in the intensive care unit. Curr Opin Crit Care 2004; 10:347-53. [PMID: 15385750 DOI: 10.1097/01.ccx.0000139364.53198.fd] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW In the past 12 years, atherosclerosis and the acute coronary syndromes have turned out to be thromboinflammatory diseases. Recent data suggest that inflammation also plays an important role in the pathogenesis and outcome of cardiogenic shock. This review will summarize recent advances in the understanding of the pathophysiology of cardiogenic shock related to the inflammatory network and will discuss recent findings in the treatment of patients with cardiogenic shock in relation to these new insights. RECENT FINDINGS The glycoprotein IIb/IIIa antagonist abciximab has recently been found to be especially useful in the treatment of patients with cardiogenic shock undergoing coronary revascularization with stent implantation, reducing mortality in retrospective analyses from 40 to 50% down to 18 to 26%. Although it remains to be proved whether this is really due to their antiinflammatory effects, other drugs with clear antiinflammatory properties, like the nitric oxide synthase inhibitors L-NAME/L-NMMA, have recently been tested in small series of patients with refractory shock despite coronary revascularization based on the hypothesis that inflammation and impaired vasoreactivity are crucial for the pathogenesis and outcome of cardiogenic shock, with promising results. Other drugs, like a recently developed antibody fragment directed against C5 (pexelizumab) or high-dose statins, await testing in this population with a very high mortality rate. CONCLUSION The promising results of studies that tested a potential benefit of drugs with clear or potential antiinflammatory/immunomodulatory properties in patients with cardiogenic shock underscores the importance of the inflammatory network in the pathogenesis and outcome of this devastating complication of cardiovascular disease.
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Affiliation(s)
- Alexander Geppert
- Cardiovascular Intensive Care Unit, 3 Department of Medicine, Wilhelminenhospital, Vienna, Austria.
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572
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Abstract
Successful treatment with inotropes and vasopressors depends on an understanding of the interplay of flow, pressure, and resistance in the cardiovascular system and an appreciation of the pathophysiologic mechanisms leading to inadequate tissue perfusion. Any treatment strategy is necessarily a compromise between the requirements of different vascular beds.Furthermore. the underlying hemodynamic derangements can change rapidly. Therefore. inotropes and vasopressors should be titrated to measures of improved hemodynamic status, and the treatments should be frequently reviewed.
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Affiliation(s)
- Kevin T T Corley
- Neonatal Foal Intensive Care Programme, Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, United Kingdom.
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573
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Affiliation(s)
- John C Marshall
- Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
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574
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Enkhbaatar P, Traber DL. Pathophysiology of acute lung injury in combined burn and smoke inhalation injury. Clin Sci (Lond) 2004; 107:137-43. [PMID: 15151496 DOI: 10.1042/cs20040135] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 05/14/2004] [Accepted: 05/19/2004] [Indexed: 11/17/2022]
Abstract
In the U.S.A., more than 1 million burn injuries occur every year. Although the survival from burn injury has increased in recent years with the development of effective fluid resuscitation management and early surgical excision of burned tissue, the mortality of burn injury is still high. In these fire victims, progressive pulmonary failure and cardiovascular dysfunction are important determinants of morbidity and mortality. The morbidity and mortality increases when burn injury is associated with smoke inhalation. In the present review, we will describe the pathophysiological aspects of acute lung injury induced by combined burn and smoke inhalation and examine various therapeutic approaches.
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Affiliation(s)
- Perenlei Enkhbaatar
- Department of Anesthesiology, University of Texas Medical Branch, 610 Texas Ave, Galveston, TX 77555, USA
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575
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Affiliation(s)
- Robert W Schrier
- Department of Medicine, University of Colorado Health Sciences Center, Denver 80262, USA.
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576
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Elsasser TH, Kahl S, MacLeod C, Nicholson B, Sartin JL, Li C. Mechanisms underlying growth hormone effects in augmenting nitric oxide production and protein tyrosine nitration during endotoxin challenge. Endocrinology 2004; 145:3413-23. [PMID: 15044352 DOI: 10.1210/en.2004-0063] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The present study defined the effects of GH administration on components of the nitric oxide (NO)-generating cascade to account for observed increases in NO production and protein nitration after an immune challenge. Calves were assigned to groups with or without GH treatment (100 microg GH/kg body weight or placebo im, daily for 12 d) and with or without low-level endotoxin [lipopolysaccharide (LPS), 2.5 microg/kg, or placebo, iv]. Plasma was obtained for estimation of NO changes as [NO(2)(-) + NO(3)(-)] (NO(x)). Transcutaneous liver biopsies were collected for measurement of protein tyrosine nitration, cationic amino acid transporter (CAT)-2 mRNA transporter, and constitutive NO synthase (cNOS), inducible NOS (iNOS), and arginase activity. Liver protein nitration increased more than 10-fold 24 h after LPS and an additional 2-fold in animals treated with GH before LPS. GH increased plasma NO(x) after LPS to levels 27% greater than those measured in non-GH-treated calves. LPS increased CAT-2 mRNA after LPS; GH was associated with a 24% reduction in CAT-2 mRNA content at the peak time response. cNOS activity was 3-fold greater than iNOS after LPS. NOS activities were increased 140% (cNOS) at 3 h and 169% (iNOS) at 6 h, respectively, after LPS; GH treatment increased cNOS activity and the phosphorylation of endothelial NOS after LPS more than 2-fold over that measured in non-GH-treated calves. The data suggest that an increased production of nitrated protein develops in the liver during low-level, proinflammatory stress, and nitration is increased by GH administration through a direct effect on the competing activities of NOS and arginase, modulatable critical control points in the proinflammatory cascade.
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Affiliation(s)
- Ted H Elsasser
- United States Department of Agriculture, Agricultural Research Service, Growth Biology Laboratory, B-200, Room 201, Beltsville Agricultural Research Center-East, Beltsville, Maryland 20705, USA.
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577
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Renes MH, van der Hoeven JG. Administration of Nitric Oxide Synthase Inhibitor 546C88 in Septic Shock. Crit Care Med 2004; 32:1625; author reply 1625-6. [PMID: 15241124 DOI: 10.1097/01.ccm.0000128985.77253.c8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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578
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Administration of Nitric Oxide Synthase Inhibitor 546C88 in Septic Shock: The authors reply. Crit Care Med 2004. [DOI: 10.1097/01.ccm.0000131205.75130.dc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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579
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D'Agnillo F. Redox active hemoglobin enhances lipopolysaccharide-induced injury to cultured bovine endothelial cells. Am J Physiol Heart Circ Physiol 2004; 287:H1875-82. [PMID: 15205170 DOI: 10.1152/ajpheart.00164.2004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of cell-free hemoglobin with lipopolysaccharide (LPS) is thought to aggravate the pathophysiology of sepsis and/or septic shock. This study examines the possible modulatory role of cell-free hemoglobin on LPS-induced apoptosis of cultured bovine aortic endothelial cells. Experiments were performed with or without fetal bovine serum, a source of LPS-binding protein and soluble CD14. In the absence of serum, LPS alone or coincubated with purified bovine hemoglobin (BvHb), human hemoglobin (Hb), or alpha-cross-linked Hb (alphaalphaHb) did not induce apoptosis. In the presence of serum, LPS induced significant apoptosis. LPS combined with BvHb, Hb, or alphaalphaHb produced the same extent of apoptosis as LPS alone. To examine whether the H(2)O(2)-driven redox activity of hemoglobin alters LPS-induced apoptosis, glucose oxidase was added to the system to generate a subtoxic flux of H(2)O(2). The combined treatment of LPS, glucose oxidase, and BvHb, Hb, or alphaalphaHb enhanced apoptosis compared with LPS alone. These findings support a possible mechanism whereby the redox cycling of hemoglobin, and not its direct interaction with LPS, contributes to the hemoglobin-mediated enhancement of LPS-related pathophysiology.
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Affiliation(s)
- Felice D'Agnillo
- Center for Biologics Evaluation and Research, Food and Drug Administration, 29 Lincoln Drive, Bldg. 29, Rm. 129, Bethesda, MD 20892, USA.
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580
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Spronk PE, Zandstra DF, Ince C. Bench-to-bedside review: sepsis is a disease of the microcirculation. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2004; 8:462-8. [PMID: 15566617 PMCID: PMC1065042 DOI: 10.1186/cc2894] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Microcirculatory perfusion is disturbed in sepsis. Recent research has shown that maintaining systemic blood pressure is associated with inadequate perfusion of the microcirculation in sepsis. Microcirculatory perfusion is regulated by an intricate interplay of many neuroendocrine and paracrine pathways, which makes blood flow though this microvascular network a heterogeneous process. Owing to an increased microcirculatory resistance, a maldistribution of blood flow occurs with a decreased systemic vascular resistance due to shunting phenomena. Therapy in shock is aimed at the optimization of cardiac function, arterial hemoglobin saturation and tissue perfusion. This will mean the correction of hypovolemia and the restoration of an evenly distributed microcirculatory flow and adequate oxygen transport. A practical clinical score for the definition of shock is proposed and a novel technique for bedside visualization of the capillary network is discussed, including its possible implications for the treatment of septic shock patients with vasodilators to open the microcirculation.
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Affiliation(s)
- Peter E Spronk
- Department of Intensive Care Medicine, Gelre ziekenhuizen, Apeldoorn, The Netherlands.
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581
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Crawford JH, Chacko BK, Pruitt HM, Piknova B, Hogg N, Patel RP. Transduction of NO-bioactivity by the red blood cell in sepsis: novel mechanisms of vasodilation during acute inflammatory disease. Blood 2004; 104:1375-82. [PMID: 15150083 DOI: 10.1182/blood-2004-03-0880] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Sepsis is an acute inflammatory disease characterized by dysfunctional blood flow and hypotension. Nitric oxide (NO) is elevated during sepsis and plays an integral role in the associated vascular pathology. However, precise mechanisms and functions of NO in sepsis remain unclear. In this study, we show that red blood cells (RBCs) are foci for nitrosative reactions during acute inflammation, resulting in the formation of cells that can promote systemic vascular relaxation in an uncontrolled manner. Specifically, using experimental models of endotoxemia and surgical sepsis, NO adducts were found in the RBCs, including S-nitrosohemoglobin (SNOHb). These RBCs, referred to as septic RBCs, spontaneously stimulated vasodilation in a manner consistent with elevated SNOHb concentrations. Moreover, relaxation was cyclic guanosine monophosphate (cGMP) dependent and was inhibited by RBC lysis and glutathione but not by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5 tetramethylimidazoline 1-oxyl 3-oxide (C-PTIO). The potential mechanism of septic RBC-mediated vasorelaxation is discussed and may involve the intermediate, nitroxyl (HNO). Coupled with data showing that NO adducts in septic RBCs were dependent on the inducible nitric oxide synthase and correlated with plasma nitrite, these findings provide a novel framework to understand mechanisms underlying dysfunctional blood flow responses during sepsis. Specifically, the concept that RBCs directly mediate systemic hypotension through NO-dependent mechanisms is discussed.
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Affiliation(s)
- Jack H Crawford
- Department of Pathology, University of Alabama at Birmingham, 901 19th St S, BMR II Rm 307, Birmingham, AL 35294, USA
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582
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Phillip Dellinger R, Parrillo JE. Mediator modulation therapy of severe sepsis and septic shock: Does it work? *. Crit Care Med 2004; 32:282-6. [PMID: 14707593 DOI: 10.1097/01.ccm.0000105423.06091.8e] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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583
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Bateman RM, Sharpe MD, Ellis CG. Bench-to-bedside review: microvascular dysfunction in sepsis--hemodynamics, oxygen transport, and nitric oxide. Crit Care 2003; 7:359-73. [PMID: 12974969 PMCID: PMC270719 DOI: 10.1186/cc2353] [Citation(s) in RCA: 211] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The microcirculation is a complex and integrated system that supplies and distributes oxygen throughout the tissues. The red blood cell (RBC) facilitates convective oxygen transport via co-operative binding with hemoglobin. In the microcirculation oxygen diffuses from the RBC into neighboring tissues, where it is consumed by mitochondria. Evidence suggests that the RBC acts as deliverer of oxygen and 'sensor' of local oxygen gradients. Within vascular beds RBCs are distributed actively by arteriolar tone and passively by rheologic factors, including vessel geometry and RBC deformability. Microvascular oxygen transport is determined by microvascular geometry, hemodynamics, and RBC hemoglobin oxygen saturation. Sepsis causes abnormal microvascular oxygen transport as significant numbers of capillaries stop flowing and the microcirculation fails to compensate for decreased functional capillary density. The resulting maldistribution of RBC flow results in a mismatch of oxygen delivery with oxygen demand that affects both critical oxygen delivery and oxygen extraction ratio. Nitric oxide (NO) maintains microvascular homeostasis by regulating arteriolar tone, RBC deformability, leukocyte and platelet adhesion to endothelial cells, and blood volume. NO also regulates mitochondrial respiration. During sepsis, NO over-production mediates systemic hypotension and microvascular reactivity, and is seemingly protective of microvascular blood flow.
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Affiliation(s)
- Ryon M Bateman
- Vascular Biology Program, Lawson Health Research Institute, The University of Western Ontario, London, Ontario, Canada.
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584
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Vallet B. Bench-to-bedside review: endothelial cell dysfunction in severe sepsis: a role in organ dysfunction? Crit Care 2003; 7:130-8. [PMID: 12720559 PMCID: PMC270612 DOI: 10.1186/cc1864] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
During the past decade a unifying hypothesis has been developed to explain the vascular changes that occur in septic shock on the basis of the effect of inflammatory mediators on the vascular endothelium. The vascular endothelium plays a central role in the control of microvascular flow, and it has been proposed that widespread vascular endothelial activation, dysfunction and eventually injury occurs in septic shock, ultimately resulting in multiorgan failure. This has been characterized in various models of experimental septic shock. Now, direct and indirect evidence for endothelial cell alteration in humans during septic shock is emerging. The present review details recently published literature on this rapidly evolving topic.
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Affiliation(s)
- Benoît Vallet
- Department of Anesthesiology and Intensive Care, University Hospital, Lille, France.
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585
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