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- Eriksson, Mats, et al.
(författare)
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Increased platelet microvesicle formation is associated with mortality ina porcine model of endotoxemia
- 1998
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 42:5, s. 551-557
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Tidskriftsartikel (refereegranskat)abstract
- Background:Gram-negative sepsis in humans and endotoxemia in pigs induce the formation of platelet microvesicles. These microvesicles are active in homeostasis and may thus contribute to the outcome in patients with activated coagulation and fibrinolysis. We decided to prospectively evaluate the effects of endotoxemia on microvesicle formation and some common physiologic variables against survival in a porcine model.Methods:Nineteen included pigs were anesthetized, monitored and subjected to an infusion of E. coli endotoxin. Microvesicle formation was determined by flow cytometry.Results:The formation of microvesicles was significantly increased in the 6 pigs that died during endotoxin exposure. This increased formation became significant from the 3rd hour of endotoxemia. Microvesicle formation did not increase in surviving endotoxemic pigs. Cardiac index, mean arterial blood pressure, base excess and systemic vascular resistance index were distinctly reduced in the animals that died as compared to those surviving the endotoxemic period.Conclusion:The increased formation of platelet microvesicles seems to be associated with poor prognosis in porcine endotoxemia. Since microvesicles are active in coagulation, they may contribute to the derangement of the coagulation system caused by endotoxemia. Different degrees of microvesicle formation may reflect inter-individual responses to a given challenge.
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- Kiiski, Ritva, et al.
(författare)
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An inhibitor of angiotensin converting enzyme (enalapril) augments endotoxin-induced hypotension in the pig
- 1999
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Ingår i: Upsala Journal of Medical Sciences. - 0300-9734. ; 104:2, s. 163-176
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Tidskriftsartikel (refereegranskat)abstract
- Septic shock causes an extensive inflammatory reaction including increased capillary leakage and a decrease in systemic blood pressure. Human septic shock can be replicated in the endotoxaemic pig. Angiotensin converting enzyme (ACE) is involved in the degradation of bradykinin, an inflammatory mediator, and in the regulation of blood pressure. Inhibition of ACE is a common approach to reduce hypertension as well as left ventricular insufficiency. Fifteen anaesthetised pigs received a continuous 3 h endotoxin infusion. The animals were randomly given an inhibitor of ACE (enalpril) [at a dose (0.5 mg x kg-1) that did not per se reduce mean arterial blood pressure (MAP); (n = 7)], or the corresponding volume of saline (n = 8). Another seven pigs were randomised for treatment with enalapril (0.5 mg x kg-1) + saline (n = 3). Four pigs were randomised to serve as untreated controls (saline + saline). Basic physiologic variables were registered. Endotoxaemia progressively reduced MAP. This decrease was significantly augmented by enalapril. Hypovolemia caused by increased permeability or salt/water excretion did not seem to explain this effect as neither blood haemoglobin nor plasma sodium differed between the two groups of endotoxaemic pigs. Inhibitors of ACE are known to potentiate the cardio-depressant effect of bradykinin. This may explain the reduction in MAP by enalapril during porcine endotoxaemia.
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- Larsson, Anders
(författare)
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Inhibited electrical discharges in air
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modem society requires a stable electricity supply, the reliability of which is partlydetermined by the dielectric strength of the outdoor high-voltage insulation systems.This thesis concentrates upon one particular discharge phenomenon that occurs whensuch a system is subjected to rain, namely the inhibited discharge. This is a dischargewhere the energy input into the discharge channel is limited by the presence of a largeseries resistor in the discharge circuit.Two experimental arrangements have been used: A quasi-uniform 10 mm electrodegap (simulating discharges between water drops) and a rod-to-plane 1 m electrode gap(simulating the flashover of a high-voltage post insulator).The presence of the series resistance caused no increase in the disruptive dischargevoltage for the 10 mm gap, but for the 1 m gap it induced an increase that was morepronounced for negative than positive polarity.The transition from a cold discharge to a hot plasma was significantly prolongedwhen a large series resistance was introduced in the discharge circuit. This is interestingfor engineering purposes since it increases the time window in which action can betaken before the end of the disruptive discharge.A five order-of-magnitude difference in the peak streamer-to-spark transition current(1 mA - 100 A) was found in the literature for 10 mm gaps. This difference has notbeen thoroughly investigated previously. Here an explanation is suggested for thisphenomenon.The experimental results revealed that the streamer propagation was not inhibited bythe presence of a large series resistance in the discharge circuit, but the final jump was.The effect upon streamer propagation was confirmed by calculations using a well-established streamer model. A final-jump model was derived as part of the work presented here and good agreement was obtained between the experiments and the calculations. This model should be useful in the design of high-voltage insulators.
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