| 1. |
- Blind, Per-Jonas, et al.
(författare)
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Microdialysis in early detection of temporary pancreatic ischemia in a porcine model
- 2012
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Ingår i: European Surgical Research. - : S. Karger AG. - 0014-312X .- 1421-9921. ; 49:3-4, s. 113-120
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ischemic injury to the pancreas occurs in various clinical conditions. A method for online monitoring of pathophysiological events in pancreatic parenchyma is missing. Aims: To assess the timing of microdialysis (MD) technique response on temporary changes in pancreatic perfusion, and to evaluate the relationship between MD data and systemic markers of anaerobic metabolism and inflammation. Methods: In anaesthetized normoventilated pigs, MD probes were placed in right (control) and left (ischemic) pancreatic lobes, respectively. Following the clamping of the vessels, ischemia was verified by tissue oxygen tension (PtiO2) measurements. Results: PtiO2 decreased within 20 min after the clamping of the vessels, already returning to baseline levels at the first sampling point after the removal of the clamp. MD lactate levels increased, whereas pyruvate and glucose levels decreased at 20 min after the induction of ischemia. These trends continued until the end of ischemia and returned to baseline following reperfusion. Serum lactate, amylase and tumor necrosis factor-alpha levels decreased throughout the protocol time. Conclusion: MD data were in concordance with changes in PtiO2, which is indicative of local anaerobic metabolism. MD allowed the detection of pathophysiological processes within the ischemic pancreas at a stage when no elevations of systemic markers of ischemia or inflammation were observed.
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| 2. |
- Abrahamsson, Pernilla, 1972-, et al.
(författare)
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An assessment of calibration and performance of the microdialysis system
- 2005
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier. - 0731-7085 .- 1873-264X. ; 39:3-4, s. 730-734
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Tidskriftsartikel (refereegranskat)abstract
- To improve the reliability of microdialysis measurements of tissue concentrations of metabolic substances, this study was designed to test both the performance and the internal validity of the microdialysis methods in the hands of our research group. The stability of the CMA 600 analyser was tested with a known glucose solution in 72 standard microvials and in 48 plastic vials. To evaluate if variation in sampling time makes any difference in sample concentration (recovery), sampling times of 10, 20 and 30 min were compared in vitro with a constant flow rate of 1 microl/min. For testing of sampling times at different flow rates, an in vitro study was performed in which a constant sample volume of 10 microl was obtained. With the no net flux method, the actual concentration of glucose and urea in subcutaneous tissue was measured. The CMA 600 glucose analysis function was accurate and stable with a coefficient of variability (CV) of 0.2-0.55%. There was no difference in recovery for the CMA 60 catheter for glucose when sampling times were varied. Higher flow rates resulted in decreased recovery. Subcutaneous tissue concentrations of glucose and urea were 4.4 mmol/l and 4.1 mmol/l, respectively. To conclude, this work describes an internal validation of our use of the microdialysis system by calibration of vials and catheters. Internal validation is necessary in order to be certain of adequate sampling times, flow rates and sampling volumes. With this in mind, the microdialysis technique is useful and appropriate for in vivo studies on tissue metabolism.
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| 3. |
- Abrahamsson, Pernilla, 1972-, et al.
(författare)
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Comparison between outcome of surface and intraparenchymatous sampling using microdialysis in an experimental liver ischemia model
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Introduction. We recently have shown that samples from MD probes placed on the surface of the heart reflect metabolic events in the myocardium. This new interesting observation challenges us to consider whether surface application of MD applies to other parenchymatous organs and their surfaces. Material and methods. In thirteen anesthetized pigs transient liver ischemia was achieved by occlusion of arterial and venous inflow to the liver. Two probes on liver surface, and two in parenchyma were perfused with a flow rate of 1 µL/min (n=13). An identical set up was used for probes with a flow rate of 2 µL/min (n=9). Samples were collected for every 15 minute period during 60 minutes of baseline, 45 minutes of ischemia and 60 minutes of reperfusion. Lactate, glucose, pyruvate and glycerol were analysed in MD samples. We focused on relative changes in the present paper. Results. There was a strong agreement in relative lactate and glucose levels between probes placed on liver surface and parenchyma. No significant differences in relative changes of lactate and glucose levels were seen between samples from surface probes and probes in liver parenchyma during equilibration, baseline, ischemia or reperfusion with a flow rate of 1 µL/min. Conclusion. MD sampling applied on the liver surface is a new application area for the MD technique, and may be used to monitor liver metabolism both during physiological and pathophysiological conditions.
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| 4. |
- Abrahamsson, Pernilla, et al.
(författare)
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Detection of myocardial ischaemia using surface microdialysis on the beating heart
- 2011
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 31:3, s. 175-181
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Tidskriftsartikel (refereegranskat)abstract
- Microdialysis (MD) can be used to study metabolism of the beating heart. We investigated whether microdialysis results obtained from epicardial (surface) sampling reflect acute changes in the same way as myocardial sampling from within the substance of the ventricular wall. In anaesthetized open-thorax pigs a coronary snare was placed. One microdialysis probe was placed with the sampling membrane intramyocardially (myocardial), and a second probe was placed with the sampling membrane epicardially (surface), both in the area which was made ischaemic. Ten minutes collection intervals were used for microdialysis samples. Samples from 19 pigs were analysed for lactate, glucose, pyruvate and glycerol during equilibration, baseline, ischaemia and reperfusion periods. For both probes (surface and myocardial), a total of 475 paired simultaneous samples were analysed. Results from analyses showed no differences in relative changes for glucose, lactate and glycerol during baseline, ischaemia and reperfusion. Surface microdialysis sampling is a new application of the microdialysis technique that shows promise and should be further studied.
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| 5. |
- Abrahamsson, Pernilla, 1972-
(författare)
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Methodological aspects on microdialysis sampling and measurements
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The microdialysis (MD) technique is widely spread and used both experimentally and in clinical practice. The MD technique allows continuous collection of small molecules such as glucose, lactate, pyruvate and glycerol. Samples are often analysed using the CMA 600 analyser, an enzymatic and colorimetric analyser. Data evaluating the performance of the CMA 600 analysis system and associated sample handling are sparse. The aim of this work was to identify sources of variability related to handling of microdialysis samples and sources of error associated with use of the CMA 600 analyser. Further, to develop and compare different application techniques of the microdialysis probes both within an organ and on the surface of an organ. Material and Methods: Papers I and II are mainly in vitro studies with the exception of the No Net Flux calibration method in paper I where a pig model (n=7) was used to examine the true concentration of glucose and urea in subcutaneous tissue. Flow rate, sampling time, vial and caps material and performance of the analyser device (CMA 600) were examined. In papers III and IV normoventilated anaesthetised pigs (n=33) were used. In paper III, heart ischemia was used as intervention to compare microdialysis measurements in the myocardium with corresponding measurements on the heart surface. In paper IV, microdialysis measurements in the liver parenchyma were compared with measurements on the liver surface in association with induced liver ischemia. All animal studies were approved by the Animal Experimental Ethics Committee at Umeå University Sweden. Results: In paper I we succeeded to measure true concentrations of glucose (4.4 mmol/L) and Urea (4.1 mmol/L) in subcutaneous tissue. Paper II showed that for a batch analyse of 24 samples it is preferred to store microdialysis samples in glass vials with crimp caps. For reliable results, samples should be centrifuged before analysis. Paper III showed a new application area for microdialysis sampling from the heart, i.e. surface sampling. The surface probe and myocardial probe (in the myocardium) showed a similar pattern for glucose, lactate and glycerol during baseline, short ischemic and long ischemic interventions. In paper IV, a similar pattern was observed as in paper III, i.e. data obtained from the probe on the liver surface showed no differences compared with data from the probe in liver parenchyma for glucose, lactate and glycerol concentrations during baseline, ischemic and reperfusion interventions. Conclusion: The MD technique is adequate for local metabolic monitoring, but requires methodological considerations before starting a new experimental serie. It is important to consider factors such as flow rate, sampling time and handling of samples in association with the analysis device chosen. The main finding in this thesis is that analyses of glucose, lactate and glycerol in samples from the heart surface and liver surface reflect concentrations sampled from the myocardium and liver parenchyma, respectively.
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| 6. |
- Abrahamsson, Pernilla, 1972-, et al.
(författare)
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Optimised sample handling in association with use of the CMA 600 analyser
- 2008
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier. - 0731-7085 .- 1873-264X. ; 48:5, s. 940-945
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Tidskriftsartikel (refereegranskat)abstract
- A large degree of variability for batched analysis of serially collected microdialysis samples measured with the CMA 600 analyser has been described. This study was designed to identify sources of variability related to sample handling. Standard concentrations of four solutes were placed in microdialysis vials and then stored and analysed at intervals. Results were analysed for variability related to vial and cap type, duration and temperature of storage, centrifugation and re-analysis. The main results were that centrifugation of samples reduced variability. When a batch of 24 samples was analysed, the use of crimp caps reduced evaporation. Samples in glass vials with crimp caps could be stored in a refrigerator for up to 14 days without large variability in concentration compared to plastic vials which demonstrated variability already when stored for more than 1 day. We conclude that variability in microdialysis results can occur in relation to storage and analysis routines if routines are not optimised concerning evaporation. Centrifugation before analyses, glass vials with crimp caps even during frozen storage, and attention to minimal times for samples to be uncapped during analysis all contribute to minimise variability in the handling and analysis of microdialysis samples.
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| 7. |
- Abrahamsson, Pernilla, et al.
(författare)
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Outcome of microdialysis sampling on liver surface and parenchyma
- 2016
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 0022-4804 .- 1095-8673. ; 200:2, s. 480-487
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Tidskriftsartikel (refereegranskat)abstract
- Background: To investigate whether surface microdialysis (μD) sampling in probes covered by a plastic film, as compared to noncovered and to intraparenchymatous probes, would increase the technique's sensitivity for pathophysiologic events occurring in a liver ischemia-reperfusion model. Placement of μD probes in the parenchyma of an organ, as is conventionally done, may cause adverse effects, e.g., bleeding, possibly influencing outcome.Methods: A transient ischemia-reperfusion model of the liver was used in six anesthetized normoventilated pigs. μD probes were placed in the parenchyma and on the liver surface. Surface probes were either left uncovered or were covered by plastic film.Results: Lactate and glucose levels were significantly higher in plastic film covered probes than in uncovered surface probes throughout the ischemic period. Glycerol levels were significantly higher in plastic film covered probes than in uncovered surface probes at 30 and 45 min into ischemia.Conclusions: Covering the μD probe increases the sensibility of the μD–technique in monitoring an ischemic insult and reperfusion in the liver. These findings confirm that the principle of surface μD works, possibly replacing need of intraparenchymatous placement of μD probes. Surface μD seemingly allows, noninvasively from an organ's surface, via the extracellular compartment, assessment of intracellular metabolic events. The finding that covered surface μD probes allows detection of local metabolic changes earlier than do intraparenchymatous probes, merit further investigation focusing on μD probe design.
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| 8. |
- Abrahamsson, Pernilla, et al.
(författare)
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Surface microdialysis sampling : a new approach described in a liver ischaemia model
- 2012
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:2, s. 99-105
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Tidskriftsartikel (refereegranskat)abstract
- We recently have shown that samples from microdialysis (MD) probes placed on the surface of the heart reflect metabolic events in the myocardium. This new interesting observation challenges us to consider whether surface application of MD applies to other parenchymatous organs and their surfaces. In 13 anesthetized pigs, transient liver ischaemia was achieved by occlusion of arterial and venous inflow to the liver. Two probes on liver surface and two in parenchyma were perfused with a flow rate of 1 mu l per min (n = 13). An identical set-up was used for probes with a flow rate of 2 mu l per min (n = 9). Samples were collected for every 15-min period during 60 min of baseline, 45 min of ischaemia and 60 min of reperfusion. Lactate, glucose, pyruvate and glycerol were analysed in MD samples. We focused on relative changes in the present study. There was a strong agreement in relative lactate and glucose levels between probes placed on liver surface and those on parenchyma. No significant differences in relative changes in lactate and glucose levels were seen between samples from surface probes and probes in liver parenchyma during equilibration, baseline, ischaemia or reperfusion with a flow rate of 1 mu l per min. MD sampling applied on the liver surface is a new application area for the MD technique and may be used to monitor liver metabolism during both physiological and pathophysiological conditions.
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| 9. |
- Ahlström, Katarina, 1966, et al.
(författare)
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Exogenous carbon monoxide does not affect cell membrane energy availability assessed by sarcolemmal calcium fluxes during myocardial ischaemia-reperfusion in the pig
- 2011
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Ingår i: European Journal of Anaesthesiology. - 0265-0215 .- 1365-2346. ; 28:5, s. 356-362
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Tidskriftsartikel (refereegranskat)abstract
- Carbon monoxide is thought to be cytoprotective and may hold therapeutic promise for mitigating ischaemic injury. The purpose of this study was to test low-dose carbon monoxide for protective effects in a porcine model of acute myocardial ischaemia and reperfusion. In acute open-thorax experiments in anaesthetised pigs, pretreatment with low-dose carbon monoxide (5% increase in carboxyhaemoglobin) was conducted for 120 min before localised ischaemia (45 min) and reperfusion (60 min) was performed using a coronary snare. Metabolic and injury markers were collected by microdialysis sampling in the ventricular wall. Recovery of radio-marked calcium delivered locally by microperfusate was measured to assess carbon monoxide treatment effects during ischaemia/reperfusion on the intracellular calcium pool. Coronary occlusion and ischaemia/reperfusion were analysed for 16 animals (eight in each group). Changes in glucose, lactate and pyruvate from the ischaemic area were observed during ischaemia and reperfusion interventions, though there was no difference between carbon monoxide-treated and control groups during ischaemia or reperfusion. Similar results were observed for glycerol and microdialysate Ca-45(2+) recovery. These findings show that a relatively low and clinically relevant dose of carbon monoxide did not seem to provide acute protection as indicated by metabolic, energy-related and injury markers in a porcine myocardial ischaemia/reperfusion experimental model. We conclude that protective effects of carbon monoxide related to ischaemia/reperfusion either require higher doses of carbon monoxide or occur later after reperfusion than the immediate time frame studied here. More study is needed to characterise the mechanism and time frame of carbon monoxide-related cytoprotection.
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| 10. |
- Ahlström, Katarina, 1966, et al.
(författare)
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Metabolic responses in ischemic myocardium after inhalation of carbon monoxide.
- 2009
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Ingår i: Acta Anaesthesiol Scand. - : Wiley. - 1399-6576 .- 0001-5172. ; 53:8, s. 1036-42
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To clarify the mechanisms of carbon monoxide (CO) tissue-protective effects, we studied energy metabolism in an animal model of acute coronary occlusion and pre-treatment with CO. METHODS: In anesthetized pigs, a coronary snare and microdialysis probes were placed. CO (carboxyhemoglobin 5%) was inhaled for 200 min in test animals, followed by 40 min of coronary occlusion. Microdialysate was analyzed for lactate and glucose, and myocardial tissue samples were analyzed for adenosine tri-phosphate, adenosine di-phosphate, and adenosine mono-phosphate. RESULTS: Lactate during coronary occlusion was approximately half as high in CO pre-treated animals and glucose levels decreased to a much lesser degree during ischemia. Energy charge was no different between groups. CONCLUSIONS: CO in the low-doses tested in this model results in a more favorable energy metabolic condition in that glycolysis is decreased in spite of maintained energy charge. Further work is warranted to clarify the possible mechanistic role of energy metabolism for CO protection.
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| 11. |
- Alskär, Linda C., et al.
(författare)
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Effect of lipids on absorption of carvedilol in dogs : Is coadministration of lipids as efficient as a lipid-based formulation?
- 2019
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Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 304, s. 90-100
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Tidskriftsartikel (refereegranskat)abstract
- Lipid-based formulations (LBFs) is a formulation strategy for enabling oral delivery of poorly water-soluble drugs. However, current use of this strategy is limited to a few percent of the marketed products. Reasons for that are linked to the complexity of LBFs, chemical instability of pre-dissolved drug and a limited understanding of the influence of LBF intestinal digestion on drug absorption. The aim of this study was to explore intestinal drug solubilization from a long-chain LBF, and evaluate whether coadministration of LBF is as efficient as a lipidbased drug formulation containing the pre-dissolved model drug carvedilol. Thus, solubility studies of this weak base were performed in simulated intestinal fluid (SIF) and aspirated dog intestinal fluid (DIF). DIF was collected from duodenal stomas after dosing of water and two levels (1 g and 2 g) of LBF. Similarly, the in vitro SIF solubility studies were conducted prior to, and after addition of, undigested or digested LBF. The DIF fluid was further characterized for lipid digestion products (free fatty acids) and bile salts. Subsequently, carvedilol was orally administered to dogs in a lipid-based drug formulation and coadministered with LBF, and drug plasma exposure was assessed. In addition to these studies, in vitro drug absorption from the different formulation approaches were evaluated in a lipolysis-permeation device, and the obtained data was used to evaluate the in vitro in vivo correlation. The results showed elevated concentrations of free fatty acids and bile salts in the DIF when 2 g of LBF was administered, compared to only water. As expected, the SIF and DIF solubility data revealed that carvedilol solubilization increased by the presence of lipids and lipid digestion products. Moreover, coadministration of LBF and drug demonstrated equal plasma exposure to the lipid-based drug formulation. Furthermore, evaluation of in vitro absorption resulted in the same rank order for the LBFs as in the in vivo dog study. In conclusion, this study demonstrated increased intestinal solubilization from a small amount of LBF, caused by lipid digestion products and bile secretion. The outcomes also support the use of coadministration of LBF as a potential dosing regimen in cases where it is beneficial to have the drug in the solid form, e.g. due to chemical instability in the lipid vehicle. LBFs.
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| 12. |
- Axelsson, Birger, 1957-, et al.
(författare)
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Milrinone and levosimendan during porcine myocardial ischemia : no effects on calcium overload and metabolism
- 2013
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Ingår i: Acta Anaesthesiologica Scandinavica. - : John Wiley & Sons. - 0001-5172 .- 1399-6576. ; 57:6, s. 719-728
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although inotropic stimulation is considered harmful in the presence of myocardial ischaemia, both calcium sensitisers and phosphodiesterase inhibitors may offer cardioprotection. We hypothesise that these cardioprotective effects are related to an acute alteration of myocardial metabolism. We studied in vivo effects of milrinone and levosimendan on calcium overload and ischaemic markers using left ventricular microdialysis in pigs with acute myocardial ischaemia.Methods: Anaesthetised juvenile pigs, average weight 36kg, were randomised to one of three intravenous treatment groups: milrinone 50g/kg bolus plus infusion 0.5g/kg/min (n=7), levosimendan 24g/kg plus infusion 0.2g/kg/min (n=7), or placebo (n=6) for 60min prior to and during a 45min acute regional coronary occlusion. Systemic and myocardial haemodynamics were assessed, and microdialysis was performed with catheters positioned in the left ventricular wall. 45Ca2+ was included in the microperfusate in order to assess local calcium uptake into myocardial cells. The microdialysate was analysed for glucose, lactate, pyruvate, glycerol, and for 45Ca2+ recovery.Results: During ischaemia, there were no differences in microdialysate-measured parameters between control animals and milrinone- or levosimendan-treated groups. In the pre-ischaemic period, arterial blood pressure decreased in all groups while myocardial oxygen consumption remained stable.Conclusions: These findings reject the hypothesis of an immediate energy-conserving effect of milrinone and levosimendan during acute myocardial ischaemia. On the other hand, the data show that inotropic support with milrinone and levosimendan does not worsen the metabolic parameters that were measured in the ischaemic myocardium.
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| 13. |
- Carlert, Sara, et al.
(författare)
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In Vivo Dog Intestinal Precipitation of Mebendazole : A Basic BCS Class II Drug
- 2012
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 9:10, s. 2903-2911
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate in viva intestinal precipitation of a model drug mebendazole, a basic BCS class II drug, using dogs with intestinal stomas for administration or sampling. After oral administration of a solution with an expected intestinal supersaturation of approximately 20 times the solubility, the measured supersaturation in dog intestinal fluid (DIE) was up to 10 times and, on average, only 11% of the given dose was retrieved as solid drug in the collected fluid from the stoma. The drug was rapidly absorbed with >90% of the total systemic exposure reached within three hours after duodenal administration of a solution. In silico absorption modeling showed that in vivo data were reasonably well described by a nonprecipitating solution. An in vitro model of precipitation in DIF predicted that the intestinal concentration of dissolved mebendazole would be less than 1/5 of the initial concentration within 10 min at concentrations comparable to in vivo. It was concluded that intestinal precipitation did not have any major influence on mebendazole absorption. The extent of precipitation was overpredicted in vitro given the in vivo absorption rate, and further work is needed to identify in vitro factors that could enable more accurate in vivo predictions of intestinal precipitation from solutions.
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| 14. |
- Claesson, Jonas, et al.
(författare)
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Evaluation of intestinal preconditioning in a porcine model using classic ischemic preconditioning or lung recruitment maneuvers.
- 2008
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Ingår i: Shock. - : Ovid Technologies (Wolters Kluwer Health). - 1073-2322 .- 1540-0514. ; 21:1, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- To test the hypotheses that repeated brief intestinal ischemic insults would elicit an intestinal preconditioning response to a subsequent intestinal I/R injury and that a similar response would be elicited by repeated lung recruitment maneuvers (RMs). Randomized experimental controlled animal study. University hospital animal laboratory. Eighteen anesthetized pigs. Animals were randomized to one of three groups, with six animals in each group. Control group 75-min superior mesenteric artery (SMA) occlusion followed by 60-min reperfusion. Ischemic preconditioning group, three 5-min-long SMA occlusions preceding 75-min SMA occlusion and 60-min reperfusion. Recruitment maneuver (RM) group, three 2-min-long RMs preceding 75-min SMA occlusion and 60-min reperfusion. We measured systemic and mesenteric hemodynamic parameters, jejunal mucosal perfusion, net mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygenation. Every 15 min, jejunal microdialysate samples were collected and analyzed for glucose, lactate, and glycerol. Jejunal tissue samples were collected postmortem. After occlusion of SMA, regional parameters in all groups indicated abolished perfusion and gradually increasing intraluminal microdialysate lactate and glycerol levels. At reperfusion, regional parameters indicated mesenteric hyperperfusion, whereas microdialysis markers of mucosal anaerobic metabolism and cell injury decreased, although not reaching baseline. Histological examination revealed severe mucosal injury in all groups. There were no significant differences between groups in the observed parameters. No protective preconditioning response could be observed when performing repeated brief intestinal ischemic insults or repeated lung RMs before an intestinal I/R injury.
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| 15. |
- Darwich, Adam S., et al.
(författare)
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IMI - Oral biopharmaceutics tools project - Evaluation of bottom-up PBPK prediction success part 3 : Identifying gaps in system parameters by analysing In Silico performance across different compound classes
- 2017
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 626-642
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Tidskriftsartikel (refereegranskat)abstract
- Three Physiologically Based Pharmacokinetic software packages (GI-Sim, Simcyp (R) Simulator, and GastroPlus (TM)) were evaluated as part of the Innovative Medicine Initiative Oral Biopharmaceutics Tools project (OrBiTo) during a blinded "bottom-up" anticipation of human pharmacokinetics. After data analysis of the predicted vs. measured pharmacokinetics parameters, it was found that oral bioavailability (F-oral) was underpredicted for compounds with low permeability, suggesting improper estimates of intestinal surface area, colonic absorption and/or lack of intestinal transporter information. Foralwas also underpredicted for acidic compounds, suggesting overestimation of impact of ionisation on permeation, lack of information on intestinal transporters, or underestimation of solubilisation of weak acids due to less than optimal intestinal model pH settings or underestimation of bile micelle contribution. F-oral was overpredicted for weak bases, suggesting inadequate models for precipitation or lack of in vitro precipitation information to build informed models. Relative bioavailability was underpredicted for both high logP compounds as well as poorly water-soluble compounds, suggesting inadequate models for solubility/dissolution, underperforming bile enhancement models and/or lack of biorelevant solubility measurements. These results indicate areas for improvement in model software, modelling approaches, and generation of applicable input data. However, caution is required when interpreting the impact of drug-specific properties in this exercise, as the availability of input parameters was heterogeneous and highly variable, and the modellers generally used the data "as is" in this blinded bottom-up prediction approach.
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| 16. |
- Dellenmark-Blom, Michaela, 1983, et al.
(författare)
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Postoperative morbidity and health-related quality of life in children with delayed reconstruction of esophageal atresia: a nationwide Swedish study
- 2022
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Ingår i: Orphanet Journal of Rare Diseases. - : Springer Science and Business Media LLC. - 1750-1172. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background In 10-15% of children with esophageal atresia (EA) delayed reconstruction of esophageal atresia (DREA) is necessary due to long-gap EA and/or prematurity/low birth weight. They represent a patient subgroup with high risk of complications. We aimed to evaluate postoperative morbidity and health-related quality of life (HRQOL) in a Swedish national cohort of children with DREA. Methods Postoperative morbidity, age-specific generic HRQOL (PedsQL((TM)) 4.0) and condition-specific HRQOL (The EA-QOL questionnaires) in children with DREA were compared with children with EA who had primary anastomosis (PA). Factors associated with the DREA group's HRQOL scores were analyzed using Mann-Whitney U-test and Spearman's rho. Clinical data was extracted from the medical records. Significance level was p < 0.05. Results Thirty-four out of 45 families of children with DREA were included and 30 returned the questionnaires(n = 8 children aged 2-7 years; n = 22 children aged 8-18 years). Compared to children with PA(42 children aged 2-7 years; 64 children aged 8-18 years), there were no significant differences in most early postoperative complications. At follow-up, symptom prevalence in children aged 2-7 with DREA ranged from 37.5% (heartburn) to 75% (cough). Further digestive and respiratory symptoms were present in >= 50%. In children aged 8-18, it ranged from 14.3% (vomiting) to 40.9% (cough), with other digestive and airway symptoms present in 19.0-27.3%. Except for chest tightness (2-7 years), there were no significant differences in symptom prevalence between children with DREA and PA, nor between their generic or condition-specific HRQOL scores (p > 0.05). More children with DREA underwent esophageal dilatations (both age groups), gastrostomy feeding (2-7 years), and antireflux treatment (8-18 years), p < 0.05. Days to hospital discharge after EA repair and a number of associated anomalies showed a strong negative correlation with HRQOL scores (2-7 years). Presence of cough, airway infection, swallowing difficulties and heartburn were associated with lower HRQOL scores (8-18 years), p < 0.05. Conclusions Although children with DREA need more treatments, they are not a risk group for postoperative morbidity and impaired HRQOL compared with children with PA. However, those with a long initial hospital stay, several associated anomalies and digestive or respiratory symptoms risk worse HRQOL. This is important information for clinical practice, families and patient stakeholders.
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| 17. |
- Dellenmark-Blom, Michaela, et al.
(författare)
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Prevalence of Mental Health Problems, Associated Factors, and Health-Related Quality of Life in Children with Long-Gap Esophageal Atresia in Sweden
- 2023
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Ingår i: Journal of Pediatric Surgery. - : Elsevier. - 0022-3468 .- 1531-5037. ; 58:9, s. 1646-1655
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Tidskriftsartikel (refereegranskat)abstract
- Background: Children with long-gap esophageal atresia (LGEA) face a high risk of digestive and respiratory morbidity, but their mental health outcomes have not been investigated. We aimed to identify the prevalence of mental health problems in children with LGEA, associated factors and health-related quality of life (HRQOL).Methods: Twenty-six children with LGEA aged 3-17 were recruited nationwide in Sweden. One of their parents and adolescents aged 11-17 completed information on the child's mental health (Strength and Difficulties Questionnaire), generic (PedsQL 4.0) and condition-specific HRQOL (EA-QOL). Parents gave information on current child symptomatology. Mental health level was determined using validated norms; abnormal >= 90 percentile/borderline >= 80 percentile/normal. Elevated levels were considered borderline/abnormal. Data were analyzed using descriptives, correlation and Mann-Whitney-U test. Significance level was p < 0.05.Results: Twelve children with LGEA aged 3-17 (46%) had elevated scores of >= 1 mental health domain in parent-reports, whereas 2 adolescents (15%) in self-reports. In parent-reports, 31% of the children had elevated levels of peer relationship problems, with associated factors being child sex male (p = 0.037), airway infections (p = 0.002) and disturbed night sleep (p = 0.025). Similarly, 31% showed elevated levels of hyperactivity/inattention, and associated factors were male sex (p = 0.005), asthma (p = 0.028) and disturbed night sleep (p = 0.036). Elevated levels of emotional symptoms, seen in 20%, were related to swallowing difficulties (p = 0.038) and vomiting problems (p = 0.045). Mental health problems correlated negatively with many HRQOL domains (p < 0.05).Conclusions: Children with LGEA risk mental health difficulties according to parent-reports, especially peer relationship problems and hyperactivity/inattention, with main risk factors being male sex, airway problems and sleep disturbances. This should be considered in follow-up care and research, particularly since their mental health problems may impair HRQOL.
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| 18. |
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| 19. |
- Larsen, Anne T, et al.
(författare)
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Bioavailability of cinnarizine in dogs : effect of SNEDDS loading level and correlation with cinnarizine solubilization during in vitro lipolysis
- 2013
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Ingår i: Pharmaceutical research. - : Springer Science and Business Media LLC. - 0724-8741 .- 1573-904X. ; 30:12, s. 3101-3113
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the effect of increasing the loading level of the poorly soluble drug cinnarizine in a self-nanoemulsifying drug delivery system (SNEDDS) both in vitro and in vivo.METHODS: A fixed dose of cinnarizine was administered orally to dogs in solution in different amounts of SNEDDS vehicle. Furthermore, the SNEDDSs were characterised using the dynamic in vitro lipolysis model.RESULTS: Statistical differences in bioavailability were not obtained between the different amounts of SNEDDS vehicle, in spite of differences in the tendency of cinnarizine to precipitate during in vitro lipolysis of the treatments. Use of the SNEDDS concept decreased the variation in cinnarizine exposure observed between dogs as compared to administering cinnarizine in an aqueous suspension.CONCLUSIONS: Optimization of SNEDDSs towards keeping the drug compound in solution upon in vitro lipolysis of the SNEDDSs may not be as important as previously suggested.
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| 20. |
- Margolskee, Alison, et al.
(författare)
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IMI - Oral biopharmaceutics tools project - Evaluation of bottom-up PBPK prediction success part 2 : An introduction to the simulation exercise and overview of results
- 2017
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 96, s. 610-625
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Tidskriftsartikel (refereegranskat)abstract
- Orally administered drugs are subject to a number of barriers impacting bioavailability (F-oral), causing challenges during drug and formulation development. Physiologically-based pharmacokinetic (PBPK) modelling can help during drug and formulation development by providing quantitative predictions through a systems approach. The performance of three available PBPK software packages (GI-Sim, Simcyp (R), and GastroPlus (TM)) were evaluated by comparing simulated and observed pharmacokinetic (PK) parameters. Since the availability of input parameters was heterogeneous and highly variable, caution is required when interpreting the results of this exercise. Additionally, this prospective simulation exercise may not be representative of prospective modelling in industry, as API information was limited to sparse details. 43 active pharmaceutical ingredients (APIs) from the OrBiTo database were selected for the exercise. Over 4000 simulation output files were generated, representing over 2550 study arm-institution-software combinations and approximately 600 human clinical study arms simulated with overlap. 84% of the simulated study arms represented administration of immediate release formulations, 11% prolonged or delayed release, and 5% intravenous (i.v.). Higher percentages of i.v. predicted area under the curve (AUC) were within two-fold of observed (52.9%) compared to per oral (p.o.) (37.2%), however, F-oral and relative AUC (F-rel) between p.o. formulations and solutions were generally well predicted (64.7% and 75.0%). Predictive performance declined progressing from i.v. to solution and immediate release tablet, indicating the compounding error with each layer of complexity. Overall performance was comparable to previous large-scale evaluations. A general overprediction of AUC was observed with average fold error (AFE) of 1.56 over all simulations. AFE ranged from 0.0361 to 64.0 across the 43 APIs, with 25 showing overpredictions. Discrepancies between software packages were observed for a few APIs, the largest being 606, 171, and 81.7-fold differences in AFE between SimCYP and GI-Sim, however average performance was relatively consistent across the three software platforms.
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| 21. |
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| 22. |
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| 23. |
- Waldenström, Anders, et al.
(författare)
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Ischaemic preconditioning reduces myocardial calcium overload in coronary-occluded pig hearts shown by continuous in vivo assessment using microdialysis.
- 2012
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Ingår i: Clinical physiology and functional imaging. - Malden, MA : Wiley-Blackwell. - 1475-097X .- 1475-0961. ; 32:2, s. 133-8
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Tidskriftsartikel (refereegranskat)abstract
- During ischaemia, ATP depletion leads to insufficient fuelling for Na(+) /K(+) ATPase, decreased electrochemical potential and increased influx of calcium ions. This study demonstrated a means to assess the effects of ischaemic preconditioning (IP) on the free intracellular Ca(2+) pool during prolonged ischaemia. In a porcine myocardial ischaemia model, microdialysis (MD) was used for sampling of metabolic and injury markers in IP and non-IP (control) groups. (45) Ca(2+) was delivered in microperfusate locally to ischaemic myocardium, with distribution and uptake assessed by (45) Ca(2+) recovery in microdialysate. Cardiomyocytes in vitro were exposed to a Ca(2+) ionophore and tested for (45) Ca(2+) uptake. An accentuated myocardial calcium ion influx (observed as an increased microdialysate (45) Ca(2+) recovery in the extracellular milieu) was noted in control pigs compared with IP pigs during ischaemia. Suspended cardiomyocytes preincubated with a Ca(2+) ionophore to increase the intracellular calcium ion pool and subsequently incubated with (45) Ca(2+) , displayed lower (45) Ca(2+) uptake in cells compared with control cells not exposed to the ionophore, corroborating the idea of a strong relationship between degree of intracellular calcium overload and microdialysate (45) Ca(2+) recovery. The ischaemic insult was differentially verified by metabolic and injury markers. We introduce an in vivo method for serial assessment of myocardial calcium overload during ischaemia, using a MD technique and (45) Ca(2+) inclusion. IP leads to relatively less calcium overload as assessed by this new method, and we interpret this to mean that reduction in calcium overload is an important part of the IP protective effect.
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| 24. |
- Willermark, Sara, 1988-, et al.
(författare)
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Where do we go from here? Didactic and organizational questions after the pandemic
- 2022
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Ingår i: ICERI2022 Proceedings. - Valencia : The International Academy of Technology, Education and Development. - 9788409454761 ; , s. 1144-1151
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Konferensbidrag (refereegranskat)abstract
- COVID-19 changed the educational landscape as we know it. Due to the radical transformation of schooling, there is an imminent question of what lessons have been made and which transformations ‘will stick’ and become the ‘new normal’ after the obvious threats of the pandemic subsided [1]. There is a stream of research that addresses experiences from the pandemic [2-4]. In this study, we focus on the experiences of upper secondary schools in Sweden. The purpose of this paper is to synthesize teachers' and school leaders' experiences from the pandemic and, based on that, address implications for practice for future schooling. We conduct a meta-analysis of four studies within a research project in Sweden [5-8] where the data consists of surveys and workshops with teachers and school leaders and explores their experiences of the pandemic. The results show that Sweden has worked well in an international context, at the same time there are distinct differences regarding teachers' and school leaders' perceptions of what work effort was required, the result of the teaching, and its consequences. Contribution includes synthesizing experiences from the pandemic and pointing out its implications for future education. © Copyright 2022, IATED Academy
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| 25. |
- Winsö, Ola, et al.
(författare)
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Thoracic epidural anaesthesia reduces insulin resistance and inflammatory response in experimental acute pancreatitis
- 2018
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Ingår i: Upsala Journal of Medical Sciences. - Abingdon : Taylor & Francis. - 0300-9734 .- 2000-1967. ; 123:4, s. 207-215
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The activity of the sympathetic nervous system (SNS) is crucial at an early stage in the development of an inflammatory reaction. A study of metabolic events globally and locally in the early phase of acute pancreatitis (AP), implying hampered SNS activity, is lacking. We hypothesized that thoracic epidural anaesthesia (TEA) modulates the inflammatory response and alleviates the severity of AP in pigs.MATERIAL AND METHODS: The taurocholate (TC) group (n = 8) had only TC AP. The TC + TEA group (n = 8) had AP and TEA. A control group (n = 8) underwent all the preparations, without having AP or TEA. Metabolic changes in the pancreas were evaluated by microdialysis and by histopathological examination.RESULTS: The relative increase in serum lipase concentrations was more pronounced in the TC group than in TC + TEA and control groups. A decrease in relative tissue oxygen tension (PtiO2) levels occurred one hour later in the TC + TEA group than in the TC group. The maintenance of normoglycaemia in the TC group required a higher glucose infusion rate than in the TC + TEA group. The relative decrease in serum insulin concentrations was most pronounced in the TC + TEA group.CONCLUSION: TEA attenuates the development of AP, as indicated by changes observed in haemodynamic parameters and by the easier maintenance of glucose homeostasis. Further, TEA was associated with attenuated insulin resistance and fewer local pathophysiological events.
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| 26. |
- Åberg, Anna-Maja, 1974-, et al.
(författare)
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Carbon monoxide concentration in donated blood : relation to cigarette smoking and other sources
- 2009
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Ingår i: Transfusion. - : Wiley. - 0041-1132 .- 1537-2995. ; 49:2, s. 347-353
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Carbon monoxide (CO) is normally present in the human body due to endogenous production of CO. CO can also be inhaled by exposure to external sources such as cigarette smoke, car exhaust, and fire. The purpose of this study was to investigate CO concentrations in blood from 410 blood donors at the blood center in Umea, Sweden. To further evaluate the effects of cigarette smoking on CO concentrations, the elimination time for CO was examined in six volunteer smokers after a smoked cigarette. STUDY DESIGN AND METHODS: Blood samples from whole blood donors were obtained during the blood center's routine operation. In connection with blood donations, demographic and behavioral data were collected from the donors. The CO concentration was determined using gas chromatography. RESULTS: The majority of blood donors had approximately the same CO concentration (mean, 84.5 micromol/L). In 6 percent of the samples, the concentrations were higher than 130 micromol per L. The highest CO concentration was 561 micromol per L. The main source for these high CO concentrations appeared to be cigarette smoking. In the volunteer smokers, the elimination time after a smoked cigarette varied significantly, with elimination half-lives from 4.7 to 8.4 hours. CONCLUSION: These results show that blood bank red blood cell bags may have CO concentrations above the physiologic level. The time interval between cigarette smoking and blood donation seems to be a particularly important factor for elevated CO concentrations.
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| 27. |
- Åberg, Anna-Maja, et al.
(författare)
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Circulatory effects and kinetics following acute administration of carbon monoxide in a porcine model.
- 2004
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Ingår i: Life Sciences. - : Elsevier BV. - 0024-3205 .- 1879-0631. ; 75:9, s. 1029-1039
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Tidskriftsartikel (refereegranskat)abstract
- Carbon monoxide is produced in the endothelial cells and has possible vasodilator activity through three different pathways. The aim of this study was to demonstrate circulatory effects after administration of saturated carbon monoxide blood and to describe the pharmacokinetics of carbon monoxide. Six pigs were anesthetized and 150 ml blood was removed. This blood was bubbled with carbon monoxide until the carboxyhemoglobin (COHb) levels were 90-99%. A specific amount of this blood was then injected back to the animal. At predetermined times; arterial and mixed venous blood was drawn and analyzed for carbon monoxide. Systemic and pulmonary vascular resistance index (SVRi and PVRi) were measured and exhaled air was sampled and measured for carbon monoxide. Blood samples were gathered over 300 minutes along with measurements of invasive pressures, heart rate, cardiac output, oxygen saturation (SpO2), Hb, temperature and blood gases. We conclude that this type of exposure to carbon monoxide appears to have little or no effect on general vasomotor tone and, after correcting for basal levels of carbon monoxide, elimination occurs through the lungs as predicted by a single compartment model. The half-life of carbon monoxide was determined to be 60.5 minutes (SEM 4.7).
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| 28. |
- Åberg, Anna-Maja, et al.
(författare)
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Does carbon monoxide treatment alter cytokine levels after endotoxin infusion in pigs? : A randomized controlled study
- 2008
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Ingår i: Journal of Inflammation. - : Springer Science and Business Media LLC. - 1476-9255. ; 5, s. 13.-
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: Carbon monoxide (CO) has recently been suggested to have anti-inflammatory properties, but data seem to be contradictory and species-specific. Thus, in studies on macrophages and mice, pretreatment with CO attenuated the inflammatory response after endotoxin exposure. On the other hand, human studies showed no effect of CO on the inflammatory response. Anti-inflammatory efficacy of CO has been shown at concentrations above 10% carboxyhaemoglobin. This study was undertaken to elucidate the possible anti-inflammatory effects of CO at lower CO concentrations. METHODS: Effects of CO administration on cytokine (TNF-alpha, IL-6, IL-1beta and IL-10) release were investigated in a porcine model in which a systemic inflammatory response syndrome was induced by endotoxin infusion. Endotoxin was infused in 20 anaesthetized and normoventilated pigs. Ten animals were targeted with inhaled CO to maintain 5% COHb, and 10 animals were controls. RESULTS: In the control group, mean pulmonary artery pressure increased from a baseline value of 17 mmHg (mean, n = 10) to 42 mmHg (mean, n = 10) following 1 hour of endotoxin infusion. Similar mean pulmonary artery pressure values were found in animals exposed to carbon monoxide. Plasma levels of all of the measured cytokines increased in response to the endotoxin infusion. The largest increase was observed in TNF-alpha, which peaked after 1.5 hours at 9398 pg/ml in the control group and at 13395 pg/ml in the carbon monoxide-exposed group. A similar peak was found for IL-10 while the IL-6 concentration was maximal after 2.5 hours. IL-1beta concentrations increased continuously during the experiment. There were no significant differences between carbon monoxide-exposed animals and controls in any of the measured cytokines. CONCLUSION: Our conclusion is that 5% COHb does not modify the cytokine response following endotoxin infusion in pigs.
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| 29. |
- Åberg, Anna-Maja, et al.
(författare)
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Ischaemic pre-conditioning means an increased adenosine metabolism with decreased glycolytic flow in ischaemic pig myocardium
- 2010
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 54:10, s. 1257-1264
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Tidskriftsartikel (refereegranskat)abstract
- Background Ischaemic pre-conditioning (IP) is a potent protective mechanism for limiting the myocardial damage due to ischaemia. It is not fully known as to how IP protects. The metabolism of adenosine may be an important mechanistic component. We study the role of adenosine turnover together with glycolytic flow in ischaemic myocardium subjected to IP. Methods An acute myocardial ischaemia pig model was used, with microdialysis sampling of some metabolites (lactate, adenosine, glucose, glycerol, taurine) of ischaemic myocardium. An IP group was compared with a control group before and during a prolonged ischaemia. 14C-labelled adenosine and glucose were infused through microdialysis probes, and lactate, 14C-labelled lactate, glucose, taurine and glycerol were analysed in the effluent. The glycogen content in myocardial biopsies was determined. Results The 14C-adenosine metabolism was higher as there was a higher production of 14C-lactate in IP animals compared with the controls. The glycolytic flow, measured as myocardial lactate formation, was retarded during prolonged ischaemia in IP animals. Myocardial free glucose and glycogen content decreased during the prolonged ischaemia in both groups, with higher free glucose in the IP group. We confirmed the protective effects of IP with lower myocardial concentrations of markers for cellular damage (glycerol). Conclusions This association between increased adenosine turnover and decreased glycolytic flow during prolonged ischaemia in response to IP can possibly be explained by the competitive effect for the metabolites from both glucose and adenosine metabolism for entering glycolysis. We conclude that this study provides support for an energy-metabolic explanation for the protective mechanisms of IP.
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| 30. |
- Åkesson, Oscar, et al.
(författare)
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Surface Microdialysis Detects Ischemia After Esophageal Resection : An Experimental Animal Study
- 2020
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Ingår i: Journal of Surgical Research. - : Elsevier. - 0022-4804 .- 1095-8673. ; 245, s. 537-543
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: After an esophageal resection, continuity is commonly restored by a gastric tube reconstruction and an intrathoracic anastomosis to the remaining proximal esophagus. Ischemia of the anastomotic region is considered to play a pivotal role in anastomotic leakage. Microdialysis (μD) is an excellent method to measure local biochemical substances and parameters in a specific organ or compartment aiming at early detection of ischemia. This animal study evaluates ischemia of the gastric tube reconstruction using a novel method-μD on organ surfaces. This promising method may have the potential to detect an anastomotic leakage before clinical symptoms develop.METHODS: Anesthetized normoventilated pigs were used. Surface microdialysis (S-μD) catheters and an intraparenchymal oxygen tension catheter were placed on the stomach. A gastric tube was made and the gastroepiploic artery was divided halfway along the greater curvature to produce severe ischemia at the top of the gastric tube. μD data from four locations (gastric tube, ileum and peritoneal cavity) were recorded every 20 min during the experiment. Tissue samples from all catheter sites underwent histopathological analysis. Intraparenchymal oxygen partial pressure, systemic blood tests, and hemodynamic parameters were recorded.RESULTS: S-μD data showed values indicating severe ischemia at the top of the gastric tube and intermediate ischemia at the level of transection of the gastroepiploic artery. Ischemia was verified by histopathological analysis of tissue samples and intraparenchymal oxygen tension data.CONCLUSIONS: S-μD can detect and grade severity of local ischemia in real time, in an animal model.
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| 31. |
- Åkesson, Oscar, et al.
(författare)
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Surface microdialysis measures local tissue metabolism after Ivor Lewis esophagectomy; an attempt to predict anastomotic defect
- 2023
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Ingår i: Diseases of the esophagus. - : Oxford University Press. - 1120-8694 .- 1442-2050. ; 36:8
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Tidskriftsartikel (refereegranskat)abstract
- Anastomotic defect (AD) after esophagectomy can lead to severe complications with need for surgical or endoscopic intervention. Early detection enables early treatment and can limit the consequences of the AD. As of today, there are limited methods to predict AD. In this study, we have used microdialysis (MD) to measure local metabolism at the intrathoracic anastomosis. Feasibility and possible diagnostic use were investigated. Sixty patients planned for Ivor Lewis esophagectomy were enrolled. After construction of the anastomosis, surface MD (S-MD) probes were attached to the outer surface of the esophageal remnant and the gastric conduit in close vicinity of the anastomosis and left in place for 7 postoperative days (PODs). Continuous sampling of local tissue concentrations of metabolic substances (glucose, lactate, and pyruvate) was performed postoperatively. Outcome, defined as AD or not according to Esophagectomy Complications Consensus Group definitions, was recorded at discharge or at first postoperative follow up. Difference in concentrations of metabolic substances was analyzed retrospectively between the two groups by means of artificial neural network technique. S-MD probes can be attached and removed from the gastric tube reconstruction without any adverse events. Deviating metabolite concentrations on POD 1 were associated with later development of AD. In subjects who developed AD, no difference in metabolic concentrations between the esophageal and the gastric probe was recorded. The technical failure rate of the MD probes/procedure was high. S-MD can be used in a clinical setting after Ivor Lewis esophagectomy. Deviation in local tissue metabolism on POD 1 seems to be associated with development of AD. Further development of MD probes and procedure is required to reduce technical failure.
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| 32. |
- ÅKESSON, OSCAR, et al.
(författare)
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Surface microdialysis on small bowel serosa in monitoring of ischemia
- 2016
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 0022-4804 .- 1095-8673. ; 204:1, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ischemic injury of an organ causes metabolic change from aerobic to anaerobic metabolism. It has been shown in experimental studies on the heart and liver that such conversion may be detected by conventional microdialysis probes placed intraparenchymatously, as well as on organ surfaces, by assaying lactate, pyruvate, glucose, and glycerol in dialysate. We developed a microdialysis probe (S-mu D) intended for use solely on organ surfaces. The aim of this study was to assess whether the newly developed S-mu D probe could be used for detection and monitoring of small bowel ischemia. Methods: In anesthetized normoventilated pigs, a control S-mu D probe was applied on the jejunal serosa 50 cm downstream from the duodenojejunal junction (DJJ). Starting 100 cm from DJJ, a 100-cm long ischemic segment was created by division of all mesenteric vessels. S-mu Ds were applied at 2.5, 5, 20, and 50 cm from the starting point of ischemia by serosal sutures. A standard mu D probe was placed in the abdominal cavity as a further control. Dialysate was harvested before inducing ischemia and subsequently every 20 min for 4 h. Central venous blood was drawn every hour to monitor systemic lactate, C-reactive protein, and white blood cell count. Results: Microdialysis lactate levels were significantly higher than baseline from 20 min on into protocol time in the ischemic segment and in the control S-mu D probe. The peritoneal cavity probe showed no significant elevation. Lactate levels from the ischemic segment reached a plateau at 60 min. Courses of pyruvate, glucose, and glycerol levels were in accordance with transition from an aerobic to anaerobic metabolism in the bowel wall. No statistically significant changes in hemoglobin, white blood cell count, or lactate values in central venous blood were recorded. Conclusions: Assaying the aforementioned compounds in dialysate, harvested by the newly developed S-mu D probe, allowed detection and monitoring of small bowel ischemia from 20 min on following its onset.
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