| 1. |
- Amundsen, Brage Høyem, et al.
(författare)
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A comparison of retrospectively self-gated magnetic resonance imaging and high-frequency echocardiography for characterization of left ventricular function in mice.
- 2011
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Ingår i: Laboratory animals. - : SAGE Publications. - 1758-1117 .- 0023-6772. ; 45:1, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- Non-invasive imaging methods like echocardiography and magnetic resonance imaging (MRI) are very valuable in longitudinal follow-up studies of cardiac function in small animals. To be able to compare results from studies using different methods, and explain possible differences, it is important to know the agreement between these methods. As both self-gated high-field MRI and high-frequency echocardiography (hf-echo) M-mode are potential methods for evaluation of left ventricular (LV) function in healthy mice, our aim was to assess the agreement between these two methods. Fifteen healthy female C57BL/6J mice underwent both self-gated MRI and hf-echo during the same session of light isoflurane anaesthesia. LV dimensions were estimated offline, and agreement between the methods and reproducibility for the two methods assessed using Bland-Altman methods. In summary, hf-echo M-mode had better inter-observer repeatability than self-gated MRI for all measured parameters. Compared with hf-echo, systolic posterior wall thicknesses were significantly higher when measured by MRI, while diastolic anterior wall thicknesses were found to be significantly smaller. MRI measurements of diastolic LV diameter were also higher using MRI, resulting in larger fractional shortening values compared with the values obtained by hf-echo. In conclusion, hf-echo M-mode is easy to apply, has high temporal and spatial resolution, and good reproducibility. Self-gated MRI might be advantageous in cases of abnormal LV geometry and heterogeneous regional myocardial function, especially with improvements in spatial resolution. The moderate agreement between the methods must be taken into account when comparing studies using the two modalities.
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| 2. |
- Berg, Kirsti, et al.
(författare)
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A High Precision Method for Quantitative Measurements of Reactive Oxygen Species in Frozen Biopsies
- 2014
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Ingår i: PLOS ONE. - San Francisco : Public Library of Science. - 1932-6203. ; 9:3, s. e90964-
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Tidskriftsartikel (refereegranskat)abstract
- Objective: An electron paramagnetic resonance (EPR) technique using the spin probe cyclic hydroxylamine 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH) was introduced as a versatile method for high precision quantification of reactive oxygen species, including the superoxide radical in frozen biological samples such as cell suspensions, blood or biopsies. Materials and Methods: Loss of measurement precision and accuracy due to variations in sample size and shape were minimized by assembling the sample in a well-defined volume. Measurement was carried out at low temperature (150 K) using a nitrogen flow Dewar. The signal intensity was measured from the EPR 1st derivative amplitude, and related to a sample, 3-carboxy-proxyl (CPN) with known spin concentration. Results: The absolute spin concentration could be quantified with a precision and accuracy better than +/- 10 mu M (k = 1). The spin concentration of samples stored at -80 degrees C could be reproduced after 6 months of storage well within the same error estimate. Conclusion: The absolute spin concentration in wet biological samples such as biopsies, water solutions and cell cultures could be quantified with higher precision and accuracy than normally achievable using common techniques such as flat cells, tissue cells and various capillary tubes. In addition; biological samples could be collected and stored for future incubation with spin probe, and also further stored up to at least six months before EPR analysis, without loss of signal intensity. This opens for the possibility to store and transport incubated biological samples with known accuracy of the spin concentration over time.
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| 3. |
- Berg, Kirsti, et al.
(författare)
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Acetylsalicylic acid treatment until surgery reduces oxidative stress and inflammation in patients undergoing coronary artery bypass grafting
- 2013
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Ingår i: European Journal of Cardio-Thoracic Surgery. - : Oxford University Press (OUP). - 1010-7940 .- 1873-734X. ; 43:6, s. 1154-1163
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Acetylsalicylic acid (ASA) is a cornerstone in the treatment of coronary artery disease (CAD) due to its antiplatelet effect. Cessation of aspirin before coronary artery bypass grafting (CABG) is often recommended to avoid bleeding, but the practice is controversial because it is suggested to worsen the underlying CAD. The aims of the present prospective, randomized study were to assess if ASA administration until the day before CABG decreases the oxidative load through a reduction of inflammation and myocardial damage, compared with patients with preoperative discontinuation of ASA. METHODS: Twenty patients scheduled for CABG were randomly assigned to either routine ASA-treatment (160 mg daily) until the time of surgery (ASA), or to ASA-withdrawal 7 days before surgery (No-ASA). Blood-samples were taken from a radial artery and coronary sinus, during and after surgery and analysed for 8-iso-prostaglandin (PG) F(2α); a major F(2)-isoprostane, high-sensitivity C-reactive protein (hs-CRP), cytokines and troponin T. Left ventricle Tru-Cut biopsies were taken from viable myocardium close to the left anterior descending artery just after connection to cardiopulmonary bypass, and before cardioplegia were established for gene analysis (Illumina HT-12) and immunohistochemistry (CD45). RESULTS: 8-Iso-PGF(2α) at baseline (t(1)) were 111 (277) pmol/l and 221 (490) pmol/l for ASA and No-ASA, respectively (P = 0.065). Area under the curve showed a significantly lower level in plasma concentration of 8-iso-PGF(2α) and hsCRP in the ASA group compared with the No-ASA group with (158 pM vs 297 pM, P = 0.035) and hsCRP (8.4 mg/l vs 10.1 mg/l, P = 0.013). All cytokines increased during surgery, but no significant differences between the two groups were observed. Nine genes (10 transcripts) were found with a false discovery rate (FDR) <0.1 between the ASA and No-ASA groups. CONCLUSIONS: Continued ASA treatment until the time of CABG reduced oxidative and inflammatory responses. Also, a likely beneficial effect upon myocardial injury was noticed. Although none of the genes known to be involved in oxidative stress or inflammation took a different expression in myocardial tissue, the genetic analysis showed interesting differences in the mRNA level. Further research in this field is necessary to understand the role of the genes.
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| 4. |
- Ericsson, Madelene, et al.
(författare)
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Exercise training before cardiac-specific Serca2 disruption attenuates the decline in cardiac function in mice
- 2010
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 109:6, s. 1749-1755
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Tidskriftsartikel (refereegranskat)abstract
- In the heart, function of the sarco(endo)plasmic Ca(2+)-ATPase (SERCA2) is closely linked to contractility, cardiac function, and aerobic fitness. SERCA2 function can be increased by high-intensity interval training, whereas reduced SERCA2 abundance is associated with impaired cardiac function. The working hypothesis was, therefore, that exercise training before cardiomyocyte-specific disruption of the Serca2 gene would delay the onset of cardiac dysfunction in mice. Before Serca2 gene disruption by tamoxifen, untreated SERCA2 knockout mice (Serca2(flox/flox) Tg-αMHC-MerCreMer; S2KO), and SERCA2 FF control mice (Serca2(flox/flox), S2FF) were exercise trained by high-intensity interval treadmill running for 6 wk. Both genotypes responded to training, with comparable increases in maximal oxygen uptake (Vo(2max); 17%), left ventricle weight (15%), and maximal running speed (40%). After exercise training, cardiac-specific Serca2 gene disruption was induced in both exercise trained and sedentary S2KO mice. In trained S2KO, cardiac function decreased less rapidly than in sedentary S2KO. Vo(2max) remained higher in trained S2KO the first 15 days after gene disruption. Six weeks after Serca2 disruption, cardiac output was higher in trained compared with sedentary S2KO mice. An exercise-training program attenuates the decline in cardiac performance induced by acute cardiac Serca2 gene disruption, indicating that mechanisms other than SERCA2 contribute to the favorable effect of exercise training.
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| 5. |
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| 6. |
- Ericsson, Madelene, et al.
(författare)
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High-intensity exercise training in mice with cardiomyocyte-specific disruption of Serca2
- 2010
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 108:5, s. 1311-1320
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Tidskriftsartikel (refereegranskat)abstract
- Several lines of evidence indicate that the sarco(endo)plasmic reticulum ATPase type 2 (SERCA2) is essential for maintaining myocardial calcium handling and cardiac pump function. Hence, a reduction in SERCA2 abundance is expected to reduce work performance and maximal oxygen uptake (VO2max) and to limit the response to exercise training. To test this hypothesis, we compared VO2max and exercise capacity in mice with cardiac disruption of Serca2 (SERCA2 KO) with control mice (SERCA2 FF). We also determined whether the effects on VO2max and exercise capacity could be modified by high-intensity aerobic exercise training. Treadmill running at 85-90% of VO2max started 2 wk after Serca2 gene disruption and continued for 4 wk. VO2max and maximal running speed were measured weekly in a metabolic chamber. Cardiac function was assessed by echocardiography during light anesthesia. In sedentary SERCA2 KO mice, the aerobic capacity was reduced by 50% and running speed by 28%, whereas trained SERCA2 KO mice were able to maintain maximal running speed despite a 36% decrease in VO2max. In SERCA2 FF mice, both VO2max and maximal running speed increased by training, while no changes occurred in the sedentary group. Left ventricle dimensions remained unchanged by training in both genotypes. In contrast, training induced right ventricle hypertrophy in SERCA2 KO mice. In conclusion, the SERCA2 protein is essential for sustaining cardiac pump function and exercise capacity. Nevertheless, SERCA2 KO mice were able to maintain maximal running speed in response to exercise training despite a large decrease in VO2max.
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| 7. |
- Larsson, Mikael, 1978-, et al.
(författare)
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Identification of a small molecule that stabilizes lipoprotein lipase in vitro and lowers triglycerides in vivo
- 2014
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier. - 0006-291X .- 1090-2104. ; 450:2, s. 1063-1069
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Tidskriftsartikel (refereegranskat)abstract
- Patients at increased cardiovascular risk commonly display high levels of plasma triglycerides (TGs) levels, elevated LDL cholesterol, small dense LDL particles and low levels of HDL-cholesterol. Many remain at high risk even after successful statin therapy, presumably because TG levels remain high. Lipoprotein lipase (LPL) maintains TG homeostasis in blood by hydrolysis of TG-rich lipoproteins. Efficient clearance of TGs is accompanied by increased levels of HDL-cholesterol and decreased levels of small dense LDL. Given the central role of LPL in lipid metabolism we sought to find small molecules that could increase LPL activity and serve as starting points for drug development efforts against cardiovascular disease. Using a small molecule screening approach we have identified small molecules that can protect LPL from inactivation by the controller protein angiopoietin-like protein 4 during incubations in vitro. One of the selected compounds, 50F10, was directly shown to preserve the active homodimer structure of LPL, as demonstrated by heparin-Sepharose chromatography. This compound tended to reduce fasting TG levels in normal rats. On injection to hypertriglyceridemic apolipoprotein A-V deficient mice the compound ameliorated the postprandial response after an olive oil gavage. This compound is a potential lead compound for the development of drugs that could reduce the residual risk associated with elevated TGs in dyslipidemia.
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| 8. |
- Mellerowicz, Alexandra, et al.
(författare)
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Brown Adipose Tissue Activation in the Postprandial State Reflects on Plasma Lipoproteins and Immune Cell Response in Humans
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Brown adipose tissue (BAT) has a unique to ability to use excess energy for heat production. It is therefore an attractive target organ for counteracting obesity and related metabolic diseases where overfeeding is an underlying cause. BAT has in murine models been shown to clear postprandial lipids quickly. The postprandial response is associated to systemic inflammatory alterations and an increased lipid pressure possibly driving atherosclerosis development. We hypothesized that BAT activation would affect postprandial lipid clearance and that this would reflect in an altered immune cell response.Methods: Young male volunteers were subject to an oral fat tolerance test at two separate occasions during both cold stimulation and in thermoneutral control conditions. Body temperature and EMG activity was monitored and energy expenditure (EE) was measured. Blood samples were taken at baseline and every 30 min for 2 h. Plasma lipids and the immune cell response.Results: Cold stimulation during OFTT resulted in a 19,4 % higher EE compared to warm conditions (P=0,007). Surprisingly, no changes in plasma TG were observed. A 2-fold elevation in free fatty acids (FFA) was seen in cold which also correlated positively with EE (P=0,008). Total plasma cholesterol increased compared to warm conditions by 0,56 mmol/L (P=0,050). LDL-c and HDL-c were increased in cold (0,20 mmol/L difference P=0,048 and 0,16 mmol/L P=0,002) whereas remnant-c was unaltered between the two thermal conditions. White blood cell count (WBC) after OFTT was significantly increased in cold (P = 0,018) by 0,29 х 109/L.Discussion: BAT activation in the postprandial state results in increased HDL-c, possibly indicating increased vascular lipolysis and associated pre-β HDL particle formation. Increased VLDL production due to elevated FFA levels in the cold state and might explain why plasma TG is unaltered and also why LDL-c remains at a higher concentration in the cold.Conclusions: BAT might be an attractive target for obesity treatment but potentially displays pro-atherogenic properties that must be addressed in longitudinal studies.
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| 9. |
- Mosti, M P, et al.
(författare)
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Effects of the peroxisome proliferator-activated receptor (PPAR)-δ agonist GW501516 on bone and muscle in ovariectomized rats
- 2014
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Ingår i: Endocrinology. - : Endocrine Society. - 0013-7227 .- 1945-7170. ; 155:6, s. 2178-2189
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen deficiency promotes bone loss and skeletal muscle dysfunction. Peroxisome proliferator-activated receptors (PPARs) have 3 subtypes (α, δ, and γ). PPARγ agonists induce bone loss, whereas PPARα agonists increase bone mass. Although PPARδ agonists are known to influence skeletal muscle metabolism, the skeletal effects are unsettled. This study investigated the musculoskeletal effects of the PPARδ agonist GW501516 in ovariectomized (OVX) rats. Female Sprague Dawley rats, 12 weeks of age, were allocated to a sham-operated group and 3 OVX groups; high-dose GW501516 (OVX-GW5), low-dose GW501516 (OVX-GW1), and a control group (OVX-CTR), respectively (n = 12 per group). Animals received GW501516 or vehicle (methylcellulose) daily for 4 months by gavage. Bone mineral density (BMD) was assessed by dual x-ray absorptiometry at the femur, spine, and whole body. Bone microarchitecture at the proximal tibia was assessed by microcomputed tomography, and dynamic histomorphometry was performed. Quadriceps muscle morphology and the relative expression of mitochondrial proteins were analyzed. Bone metabolism markers and metabolic markers were measured in plasma. After 4 months, the OVX-GW5 group displayed lower femoral BMD than OVX-CTR. Trabecular separation was higher in the GW-treated groups, compared with OVX-CTR. The OVX-GW5 group also exhibited lower cortical area fraction and a higher structure model index than OVX-CTR. These effects coincided with impaired bone formation in both GW groups. The OVX-GW5 group displayed elevated triglyceride levels and reduced adiponectin levels, whereas no effects on muscle morphology or mitochondrial gene expression appeared. In summary, the PPARδ agonist GW501516 negatively affected bone properties in OVX rats, whereas no effects were detected in skeletal muscle.
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| 10. |
- Nilsson, Stefan, et al.
(författare)
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Triacylglycerol-rich lipoproteins protect lipoprotein lipase from inactivation by ANGPTL3 and ANGPTL4
- 2012
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Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - Amsterdam : Elsevier. - 1388-1981 .- 1879-2618. ; 1821:10, s. 1370-1378
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Tidskriftsartikel (refereegranskat)abstract
- Lipoprotein lipase (LPL) is important for clearance of triacylglycerols (TG) from plasma both as an enzyme and as a bridging factor between lipoproteins and receptors for endocytosis. The amount of LPL at the luminal side of the capillary endothelium determines to what extent lipids are taken up. Mechanisms to control both the activity of LPL and its transport to the endothelial sites are regulated, but poorly understood. Angiopoietin-like proteins (ANGPTLs) 3 and 4 are potential control proteins for LPL, but plasma concentrations of ANGPTLs do not correlate with plasma TG levels. We investigated the effects of recombinant human N-terminal (NT) ANGPTLs3 and 4 on LPL-mediated bridging of TG-rich lipoproteins to primary mouse hepatocytes and found that the NT-ANGPTLs, in concentrations sufficient to cause inactivation of LPL in vitro, were unable to prevent LPL-mediated lipoprotein uptake. We therefore investigated the effects of lipoproteins (chylomicrons, VLDL and LDL) on the inactivation of LPL in vitro by NT-ANGPTLs3 and 4 and found that LPL activity was protected by TG-rich lipoproteins. In vivo, postprandial TG protected LPL from inactivation by recombinant NT-ANGPTL4 injected to mice. We conclude that lipoprotein-bound LPL is stabilized against inactivation by ANGPTLs. The levels of ANGPTLs found in blood may not be sufficient to overcome this stabilization. Therefore it is likely that the prime site of action of ANGPTLs on LPL is in subendothelial compartments where TG-rich lipoprotein concentration is lower than in blood. This could explain why the plasma levels of TG and ANGPTLs do not correlate.
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