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- Lipcsey, Miklós, 1975-
(författare)
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Pathophysiological, Inflammatory and Haemostatic Responses to Various Endotoxaemic Patterns : An Experimental Study in the Pig
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Septic shock is frequently seen in intensive care units and is associated with significant mortality. Endotoxin – a major mediator of the pathophysiologic responses – is released during lysis of Gram-negative bacteria. These responses can be mimicked in the endotoxaemic pig. This thesis focuses on the following topics: the inflammatory and pathophysiological responses to various endotoxin doses and infusion patterns; covariations between endotoxin induced inflammatory and pathophysiological responses; whether the biological effects of endotoxin can be modulated by clopidogrel and whether tobramycin or ceftazidime reduce plasma cytokine levels. Endotoxin induced linear log-log cytokine and F2-isoprostane responses. Leukocyte and platelet responses, pulmonary compliance, circulatory variables as well as indicators of plasma leakage and hypoperfusion exhibited log-linear responses to the endotoxin dose. Biological responses to endotoxaemia such as inflammation, hypotension, hypoperfusion and organ dysfunction were more expressed when the organism was exposed to endotoxin at a higher rate. These results may facilitate the possibility to choose relevant endotoxin administration, when experiments are set up in order to evaluate certain responses to endotoxaemia. Correlation studies between cytokines, leukocytes, platelets and the endotoxin dose were in agreement with the well-known ability of endotoxin to induce cytokine expression and to activate both primary haemostasis and leukocytes. Free radical mediated lipid peroxidation and COX-mediated inflammation correlated to cytokine expression and organ dysfunction in endotoxaemic shock. Endotoxaemic pigs pretreated with clopidogrel, exhibited a trend towards less expressed deterioration of renal function, although blocking of ADP-induced primary haemostasis is not a key mediator of endotoxin induced deterioration of renal function. Tobramycin did not neutralise the biological effects of endotoxin or the plasma levels of endotoxin, suggesting that these antibiotics do not bind to endotoxin. Reduction in IL-6 was greater in pigs treated with ceftazidime and tobramycin as compared with those given saline, indicating a possible anti-inflammatory effect of both antibiotics.
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| 2. |
- Lipcsey, Miklos, et al.
(författare)
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The brain is a source of S100B increase during endotoxemia in the pig
- 2010
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Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 110:1, s. 174-180
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Cerebral dysfunction frequently complicates septic shock. A marker of cerebral dysfunction could be of significant value in managing sedated septic patients. Plasma S100 (S100B) proteins increase in sepsis. S100B is present not only in the brain but also in other tissues. The source of this protein has not been investigated in sepsis. Our aim in this study was to determine whether the brain is an important source of S100B in an experimental sepsis model.METHODS:Twenty-seven pigs were anesthetized and randomized to either infusion of endotoxin at the rate of 1 µg · kg-1 · h-1 (n = 19) or saline (n = 8). Catheters were inserted into a cervical artery and the superior sagittal sinus. Blood samples were collected from both sites and physiologic data were registered before the start of the endotoxin infusion and hourly during the experiment. After 6 h, the animals were killed and brain tissue samples were taken from the left hemisphere. S100B in plasma was measured by enzyme-linked immunosorbent assay. Brain tissue samples were stained with biotinylated S100B antibodies.RESULTS: In the endotoxemic animals, the arterial S100B concentration increased to 442 ± 33 and 421 ± 24 ng/L at 1 and 2 h, respectively, vs 306 ± 28 and 261 ± 25 ng/L in controls (P = 0.018 and 0.00053, respectively). Mean superior sagittal sinus S100B concentrations were higher than mean arterial concentrations at all time points in the endotoxemic animals; however, significance was only reached at 2 h (P = 0.033). The focal glial S100B expression was more intense in the endotoxemic pigs than in controls (P = 0.0047).CONCLUSIONS:Our results support the hypothesis that the brain is an important source of S100B in endotoxemia even though there may be other sources. These findings make S100B a candidate as a marker of cerebral dysfunction in septic shock.
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| 3. |
- Mellhammar, Lisa, et al.
(författare)
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Sepsis - vår tids okända folksjukdom
- 2015
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 112:47
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Sperber, Jesper
(författare)
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Protective Mechanical Ventilation in Inflammatory and Ventilator-Associated Pneumonia Models
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Severe infections, trauma or major surgery can each cause a state of systemic inflammation. These causes for systemic inflammation often coexist and complicate each other. Mechanical ventilation is commonly used during major surgical procedures and when respiratory functions are failing in the intensive care setting. Although necessary, the use of mechanical ventilation can cause injury to the lungs and other organs especially under states of systemic inflammation. Moreover, a course of mechanical ventilator therapy can be complicated by ventilator-associated pneumonia, a factor greatly influencing mortality. The efforts to avoid additional ventilator-induced injury to patients are embodied in the expression ‘protective ventilation’.With the use of pig models we have examined the impact of protective ventilation on systemic inflammation, on organ-specific inflammation and on bacterial growth during pneumonia. Additionally, with a 30-hour ventilator-associated pneumonia model we examined the influence of mechanical ventilation and systemic inflammation on bacterial growth. Systemic inflammation was initiated with surgery and enhanced with endotoxin. The bacterium used was Pseudomonas aeruginosa.We found that protective ventilation during systemic inflammation attenuated the systemic inflammatory cytokine responses and reduced secondary organ damage. Moreover, the attenuated inflammatory responses were seen on the organ specific level, most clearly as reduced counts of inflammatory cytokines from the liver. Protective ventilation entailed lower bacterial counts in lung tissue after 6 hours of pneumonia. Mechanical ventilation for 24 h, before a bacterial challenge into the lungs, increased bacterial counts in lung tissue after 6 h. The addition of systemic inflammation by endotoxin during 24 h increased the bacterial counts even more. For comparison, these experiments used control groups with clinically common ventilator settings.Summarily, these results support the use of protective ventilation as a means to reduce systemic inflammation and organ injury, and to optimize bacterial clearance in states of systemic inflammation and pneumonia.
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| 5. |
- Carlsson, Markus, et al.
(författare)
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Inflammatory and circulatory effects of the reduction of endotoxin concentration in established porcine endotoxemic shock : a model of endotoxin elimination
- 2009
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 37:3, s. 1031-e4
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Tidskriftsartikel (refereegranskat)abstract
- Objective:To study whether a reduction of the endotoxin load, once a generalized inflammatory state has been established, reduces the inflammatory response and endotoxin-induced effects on circulation, hypoperfusion, and organ dysfunction.Design:Prospective parallel-grouped placebo-controlled randomized interventional experimental study.Setting:University research unit.Subjects: Healthy pigs.Interventions:The animals were subjected to a continuous endotoxin infusion rate of either 4.0 or 0.063 µg endotoxin × kg-1 × h-1 for 1, 2, or 6 hours. The 1- and 2-hour infusion groups represented the applied therapy by a reduction of the endotoxin load of 5/6 and 2/3, respectively.Measurements and Main Results:During a 6-hour experiment, laboratory and physiologic parameters were recorded hourly in 26 anesthetized and mechanically ventilated pigs. Primary end point was to detect differences in tumor necrosis factor-[alpha] (TNF-[alpha]) concentration during the last 3 hours of the experiment. Despite the early reduction of the endotoxin load, no effect on TNF-[alpha] concentration was observed. Similarly, in circulatory parameters, such as mean arterial pressure and oxygen delivery, and in platelet count and renal function, no effects were noted. However, there was some improvement in pulmonary compliance and function as determined by Pao2, Paco2, and pH. These changes were associated with slight improvements in leukocyte response and capillary leakage.Conclusions:Termination of the endotoxin infusion represents an incontestable model of endotoxin concentration reduction. Endotoxin elimination strategies applied at the TNF-[alpha] peak or later will have very little or no effect on TNF-[alpha]–mediated toxicity. Nevertheless, there was an effect on the leukocyte response that was associated with an improvement in respiratory function and microcirculation, making it impossible to rule out fully the beneficial effect of this strategy. However, the effects were limited in relation to the magnitude of the endotoxin concentration reduction and the very early application of the antiendotoxin measure.
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| 6. |
- Castegren, Markus, et al.
(författare)
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Differences in Organ Dysfunction in Endotoxin Tolerant Pigs Under Intensive Care Exposed to a Second Hit of Endotoxin
- 2012
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Ingår i: Shock. - 1073-2322 .- 1540-0514. ; 37:5, s. 501-510
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Tidskriftsartikel (refereegranskat)abstract
- Endotoxin tolerance is a well-studied phenomenon associated with a reduced inflammatory response. In the switch from an inflammatory to an anti-inflammatory response in clinical sepsis the concept of endotoxin tolerance is of obvious interest. However, only limited data exist regarding the effect of endotoxin tolerance on organ dysfunction and, therefore, this was investigated in a porcine intensive care sepsis model. Twenty-seven healthy pigs, including nine control animals, were included in the study. Twelve pigs pre-exposed to 24 h of intravenous endotoxin infusion and intensive care and six unexposed pigs were given either a high- or low-dose endotoxin challenge for 6 h. Inflammatory, circulatory, hypoperfusion and organ dysfunction parameters were followed. The inflammatory responses as well as parameters representing circulation, hypoperfusion, cardiac and renal function were all markedly attenuated in animals pre-exposed to endotoxin and intensive care as compared with animals not pre-exposed. In animals pre-exposed to endotoxin and given the high-dose of endotoxin challenge, deterioration in pulmonary function was equal to or even worse than in animals not pre-exposed.In contrast to the overall protective effect of endotoxin tolerance observed in other organ systems, the lungs of endotoxin tolerant animals demonstrated an increased responsiveness to high-dose endotoxin challenge.
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| 7. |
- Castegren, Markus, 1976-, et al.
(författare)
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Endotoxin tolerance variation over 24 h during porcine endotoxemia : association to changes in circulation and organ dysfunction
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1, s. e53221-
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Tidskriftsartikel (refereegranskat)abstract
- Endotoxin tolerance (ET), defined as reduced inflammatory responsiveness to endotoxin challenge following a first encounter with endotoxin, is an extensively studied phenomenon. Although reduced mortality and morbidity in the presence of ET has been demonstrated in animal studies, little is known about the temporal development of ET. Further, in acute respiratory distress syndrome ET correlates to the severity of the disease, suggesting a complicated relation between ET and organ dysfunction. Eighteen pigs were subjected to intensive care and a continuous endotoxin infusion for 24 h with the aim to study the time course of early ET and to relate ET to outcome in organ dysfunction. Three animals served as non-endotoxemic controls. Blood samples for cytokine analyses were taken and physiological variables registered every third hour. Production of TNF-α, IL-6, and IL-10 before and after endotoxin stimulation ex vivo was measured. The difference between cytokine values after and before ex vivo LPS stimulation (Δ-values) was calculated for all time points. ΔTNF-α was employed as the principal marker of ET and lower ΔTNF-α values were interpreted as higher levels of ET. During endotoxin infusion, there was suppression of ex vivo productions of TNF-α and IL-6 but not of IL-10 in comparison with that at 0 h. The ex vivo TNF-α values followed another time concentration curve than those in vivo. ΔTNF-α was at the lowest already at 6 h, followed by an increase during the ensuing hours. ΔTNF-α at 6 h correlated positively to blood pressure and systemic vascular resistance and negatively to cardiac index at 24 h. In this study a temporal variation of ET was demonstrated that did not follow changes in plasma TNF-α concentrations. Maximal ET occurred early in the course and the higher the ET, the more hyperdynamic the circulation 18 h later.
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