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| 2. |
- Leppanen, Olli, et al.
(författare)
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ATP depletion in macrophages in the core of advanced rabbit atherosclerotic plaques in vivo
- 2006
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Ingår i: Atherosclerosis. ; 188:2, s. 323-30
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Tidskriftsartikel (refereegranskat)abstract
- The cores of rabbit plaques in vivo are hypoxic, suggesting that ATP depletion due to an insufficient supply of oxygen and nutrients could contribute to macrophage death in atherosclerotic plaques. During hypoxia, however, macrophages maintain ATP levels by anaerobic glycolysis. To directly assess ATP and glucose metabolites in plaques in vivo, we used bioluminescence imaging to map the concentrations of ATP, glucose, glycogen, and lactate in normal and atherosclerotic rabbit aortas in vivo. Hypoxia was assessed with NITP (7-(4'-(2-nitroimidazol-1-yl)-butyl)-theophylline). Normal aortas and plaques <500 microm thick were not hypoxic and had homogenous concentrations of energy metabolites. In plaques >500 microm thick, however, the cores were characterized by ATP depletion, low concentrations of glucose and glycogen, and a high concentration of lactate. A majority of ATP-depleted macrophages within the core were viable but severely hypoxic and glucose depleted. Hyperoxia in vitro reversed the ATP depletion in macrophages in viable areas of the core. Our findings suggest that ATP depletion contributes to the death of macrophages in atherosclerotic lesions and to the formation of a necrotic core.
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| 3. |
- Rissanen, Tuomas T., et al.
(författare)
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The bottleneck stent model for chronic myocardial ischemia and heart failure in pigs
- 2013
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Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 305:9, s. H1297-H1308
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Tidskriftsartikel (refereegranskat)abstract
- A large animal model of chronic myocardial ischemia and heart failure is crucial for the development of novel therapeutic approaches. In this study we developed a novel percutaneous one-and two-vessel model for chronic myocardial ischemia using a stent coated with a polytetrafluoroethylene tube formed in a bottleneck shape. The bottleneck stent was implanted in the proximal left anterior descending (LAD) or proximal circumflex artery (LCX), or in both proximal LCX and mid LAD 1 wk later (2-vessel model), and pigs were followed for 4-5 wk. Ejection fraction (EF), infarct size, collateral growth, and myocardial perfusion were assessed. Pigs were given antiarrhythmic medication to prevent sudden death. The occlusion time of the bottleneck stent and the timing of myocardial infarction could be modulated by the duration of antiplatelet medication. Fractional flow reserve measurements and positron emission tomography imaging showed severe ischemia after bottleneck stenting covering over 50% of the left ventricle in the proximal LAD model. Complete coronary occlusion was necessary for significant collateral growth, which mostly had occurred already during the first wk after the stent occlusion. Dynamic and competitive collateral growth patterns were observed. EF declined from 64 to 41% in the LCX model and to 44% in the LAD model 4 wk after stenting with 12 and 21% infarcted left ventricle in the LCX and LAD models, respectively. The mortality was 32 and 37% in the LCX and LAD models but very (71%) high in the two-vessel disease model. The implantation of a novel bottleneck stent in the proximal LAD or LCX is a novel porcine model of reversible myocardial ischemia (open stent) and ischemic heart failure (occluded stent) and is feasible for the development of new therapeutic approaches.
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- Svensson, Jonas, et al.
(författare)
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Soot-on-snow experiment : artificial deposition of light-absorbing particles onto snow surfaces in 2018
- 2024
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Ingår i: Frontiers in Earth Science. - 2296-6463. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The absorption of shortwave irradiance in snow depends on the physical properties of snow (e.g., snow grain size and shape, liquid water content, etc.) and light-absorbing particles (LAP). Originating from natural and anthropogenic sources, LAP has been reported to accelerate snowmelt significantly in different regions globally. Yet, our process-level understanding of LAP after deposition onto snow remains rather limited. Here we investigate the impacts of artificial deposition of different LAP onto snow surfaces in an outdoor environment of northern Finland. Following LAP dry deposition into a custom-made tent standing on top of the snowpack, the albedo was followed along with the properties of snow in snow pit measurements throughout the spring season. The results showed that the albedo decay at the end of the season for the different spots were linked to the initial amount and type of LAP that were deposited onto the snowpack. Measured snow temperature profiles from LAP doped snow versus natural reference snow illustrated that the LAP affected snow had higher temperatures in the subsurface snow layers. Collected snow samples analyzed for size distribution of soot particles revealed no apparent agglomeration of soot particles during thaw-freezing events taking place during the experiment. Despite the relatively large perturbation of the experimentally deposited LAP, their impact on the season length was only up to 3 days. Additional experiments are, nevertheless, needed to better constrain the effects of LAP on snow albedo, melt rate, and other associated processes.
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