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- Ivanov, Alexander G, et al.
(författare)
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Iron deficiency in cyanobacteria causes monomerization of photosystem I trimers and reduces the capacity for state transitions and the effective absorption cross section of photosystem I in vivo.
- 2006
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 141:4, s. 1436-45
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Tidskriftsartikel (refereegranskat)abstract
- The induction of the isiA (CP43') protein in iron-stressed cyanobacteria is accompanied by the formation of a ring of 18 CP43' proteins around the photosystem I (PSI) trimer and is thought to increase the absorption cross section of PSI within the CP43'-PSI supercomplex. In contrast to these in vitro studies, our in vivo measurements failed to demonstrate any increase of the PSI absorption cross section in two strains (Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803) of iron-stressed cells. We report that iron-stressed cells exhibited a reduced capacity for state transitions and limited dark reduction of the plastoquinone pool, which accounts for the increase in PSII-related 685 nm chlorophyll fluorescence under iron deficiency. This was accompanied by lower abundance of the NADP-dehydrogenase complex and the PSI-associated subunit PsaL, as well as a reduced amount of phosphatidylglycerol. Nondenaturating polyacrylamide gel electrophoresis separation of the chlorophyll-protein complexes indicated that the monomeric form of PSI is favored over the trimeric form of PSI under iron stress. Thus, we demonstrate that the induction of CP43' does not increase the PSI functional absorption cross section of whole cells in vivo, but rather, induces monomerization of PSI trimers and reduces the capacity for state transitions. We discuss the role of CP43' as an effective energy quencher to photoprotect PSII and PSI under unfavorable environmental conditions in cyanobacteria in vivo.
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| 17. |
- Sandström, Per, 1965-, et al.
(författare)
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Highly selective inhibition of inducible nitric oxide synthase ameliorates experimental acute pancreatitis
- 2005
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Ingår i: Pancreas. - 0885-3177 .- 1536-4828. ; 30:1, s. 10-15
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES:Inducible nitric oxide synthase (iNOS) activity is increased in experimental acute pancreatitis. The aim of this study was to evaluate treatment with the selective iNOS inhibitors AR-C (AR-C102222AA) and L-NIL (L-N6-(1-iminoethyl)-lysine) in experimental acute pancreatitis.METHODS:Acute pancreatitis was induced in anesthetized Australian possums by topical administration of carbachol on the sphincter of Oddi. AR-C treatment was 2 intravenous infusions (2.5 micromol/kg over 15 minutes) at 2 and 4 hours after acute pancreatitis induction. L-NIL treatment was an intraarterial infusion (1 mg/kg/h) from 2 hours after acute pancreatitis induction. At 8 hours, pancreatic tissue was harvested and inflammation assessed (histologic score). Blood samples were collected for plasma amylase, lipase, and amino acid levels. Blood pressure, central venous pressure, supplementary fluids, and urine output were monitored.RESULTS:Treatment with AR-C or L-NIL reduced the plasma levels of amylase and the volume of supplementary fluids and improved the histological score (all P < 0.05). In animals with acute pancreatitis, plasma arginine levels were reduced (P < 0.05), while citrulline and ornithine levels increased (P < 0.05), consistent with increased nitric oxide production. Treatment with AR-C ameliorated the reduced arginine level.CONCLUSIONS:Treatment with AR-C or L-NIL, commencing 2 hours after the induction of acute pancreatitis, has significant and beneficial effects in experimental acute pancreatitis in Australian possums.
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| 19. |
- Sandström, Ulf G., et al.
(författare)
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Urban comprehensive planning - identifying barriers for the maintenance of functional habitat networks
- 2006
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Ingår i: Landscape and Urban Planning. - : Elsevier BV. - 0169-2046 .- 1872-6062. ; 75:1-2, s. 43-57
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Tidskriftsartikel (refereegranskat)abstract
- Maintaining biodiversity requires a wise combination of protection, management and recreation of habitats to secure representative and functional habitat networks. As urbanisation is increasing worldwide. town and cities are becoming the most common habitat for humankind. Accordingly, the urban landscape is becoming increasingly important for maintaining biodiversity on site, as well as for understanding the concept of biodiversity in general, and its maintenance in urban landscapes. We evaluated the extent to which Swedish urban planners experience barriers when using comprehensive planning as a tool for the maintenance of biodiversity through the provision of sufficient quantity and quality of green space. All of the six large Swedish cities, having had constant relative population growth since the beginning of the 19th century were chosen as case studies. We first defined a normative model for planning urban biodiversity and operationalised this concept by using landscape ecological principles. Structured in-depth interviews were then carried out with three planners in each city. The respondents were asked about their interest, ability, and knowledge concerning planning for functional networks of green spaces in relation to the normative model. The in-depth interviews with 18 urban planners indicated that legislation was an important driver for green space planning that they paid attention to new knowledge concerning recreation values and public health, but that biodiversity maintenance was not a high priority. There was a general agreement that local governments lack necessary resources to plan for biodiversity. A majority of the respondents mentioned geographical information systems (GIS) as an important tool to integrate knowledge about biodiversity in the planning process, and to evaluate likely consequences caused by deviations from current structure plans related to an efficient use of urban green spaces to maintain biodiversity. However, an evaluation of the answers revealed that the respondents had actually overestimated their capacity to implement the normative model. To conclude, the unanimous view was that planners were interested in the maintenance of biodiversity, but were limited by knowledge and by personnel lacking suitable qualifications, as well as by inadequate organisations. Only a minority of the respondents thought that local governments should have resources for biodiversity conservation planning. Finally, we discuss how the implementation of biodiversity policies could be improved by better integration of natural and social sciences in education and policy implementation.
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| 20. |
- Winbladh, Anders, et al.
(författare)
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Segmental ischemia of the liver - microdialysis in a novel porcine model.
- 2009
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Ingår i: European surgical research. Europäische chirurgische Forschung. Recherches chirurgicales européennes. - : S. Karger AG. - 1421-9921. ; 43:3, s. 276-285
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Segmental liver ischemia is often used in rodents to study ischemia and reperfusion injuries (IRI). There are no reports of protocols using segmental ischemia in porcine models. Microdialysis (MD) provides the opportunity to study local effects of IRI in vivo. METHODS: Eight pigs received an MD catheter placed in liver segments IV and V, respectively. All circulation to segment IV was stopped for 80 min, and reperfusion was followed for 240 min. RESULTS: During ischemia the levels of lactate, glycerol and glucose increased 3-fold (p < 0.001), 40-fold (p < 0.001) and 4-fold (p < 0.01), respectively, in the ischemic segment compared to the perfused segment, whereas the levels of pyruvate fell to a tenth of the preischemic level (p < 0.001). All values returned to baseline after reperfusion. Serum levels of aspartate aminotransferase increased (p < 0.05). Polymorphonuclear cells increased in both segments, although the density was significantly higher in segment IV. CONCLUSION: Clamping of one liver segment in pigs is a simple, stable and reproducible model to study IRI with minimal systemic effects. MD revealed no signs of anaerobic metabolism in the perfused segment but still there was an increase in the number of polymorphonuclear neutrophils in this segment, although it was lower than that in the ischemic segment.
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