| 1. |
- Danielsson, Ravi, et al.
(författare)
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Aluminium Adjuvants : a Nanomaterial used as Adjuvants in Human Vaccines for Decades
- 2018
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Ingår i: Open Biotechnology Journal. - : Bentham eBooks. - 1874-0707. ; 12, s. 140-153
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Forskningsöversikt (refereegranskat)abstract
- Background: Aluminium salts have been used for decades in vaccines as adjuvants to facilitate the adaptive immune response against co-administered antigens. Two types of aluminium adjuvant are mostly used, aluminium oxyhydroxide and aluminium hydroxyphosphate. Both types of aluminium adjuvant consist of nanoparticles that form loose, micrometre sized aggregates at circumneutral pH. Aluminium adjuvants constitute a well-documented example of administration of nanomaterials to humanswith infrequent side effects and a safety record generally regarded as excellent. However, despite its prolonged use in human and veterinary medicine, the mechanisms behind the enhanced response and the immune stimulatory effect are still by and large unknown. Methods: The present paper reviews existing ideas regarding the immunostimulatory effects of aluminium adjuvants, with a focus on the induction of an inflammatory response by cellular stress. Reviewed information was obtained from peer-reviewed scientific papers published in 1988 to date with one exception, a paper published 1931. Results: Cellular stress causes extra cellular signalling of danger associated molecular patterns (DAMPs) and upon phagocytosis of aluminium adjuvants the cells need to manage the ingested particles. Conclusion: A persistent intracellular accumulation of aluminium adjuvants will be a solid depository of sparingly soluble aluminium salts maintaining a constant concentration of Al3+ ions in the cytoplasm and this will affect multiple biochemical processes. The cell will be under constant stress and DAMP signalling will occur and we would like to suggest the maintenance of a constant concentration Al3+ ions in the cytoplasm as a general underlying feature of the immune stimulation properties of aluminium adjuvants.
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| 2. |
- Danielsson, Ravi, et al.
(författare)
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Aluminium adjuvants in vaccines : A way to modulate the immune response
- 2021
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Ingår i: Seminars in Cell and Developmental Biology. - : Elsevier. - 1084-9521 .- 1096-3634. ; 115, s. 3-9
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Tidskriftsartikel (refereegranskat)abstract
- Aluminium salts have been used as adjuvants in vaccines for almost a century, but still no clear understanding of the mechanisms behind the immune stimulating properties of aluminium based adjuvants is recognized. Aluminium adjuvants consist of aggregates and upon administration of a vaccine, the aggregates will be recognized and phagocytosed by sentinel cells such as macrophages or dendritic cells. The adjuvant aggregates will persist intracellularly, maintaining a saturated intracellular concentration of aluminium ions over an extended time. Macrophages and dendritic cells are pivotal cells of the innate immune system, linking the innate and adaptive immune systems, and become inflammatory and antigen-presenting upon activation, thus mediating the initiation of the adaptive immune system. Both types of cell are highly adaptable, and this review will discuss and highlight how the occurrence of intracellular aluminium ions over an extended time may induce the polarization of macrophages into inflammatory and antigen presenting M1 macrophages by affecting the: endosomal pH; formation of reactive oxygen species (ROS); stability of the phagosomal membrane; release of damage associated molecular patterns (DAMPs); and metabolism (metabolic re-programming). This review emphasizes that a persistent intracellular presence of aluminium ions over an extended time has the potential to affect the functionality of sentinel cells of the innate immune system, inducing polarization and activation. The immune stimulating properties of aluminium adjuvants is presumably mediated by several discrete events, however, a persistent intracellular presence of aluminium ions appears to be a key factor regarding the immune stimulating properties of aluminium based adjuvants.
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| 3. |
- Danielsson, Ravi, et al.
(författare)
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Aqueous polymer two-phase systems and their use in fragmentation and separation of biological membranes for the purpose of mapping the membrane structure.
- 2013
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Ingår i: Preparative Biochemistry & Biotechnology. - : Informa UK Limited. - 1532-2297 .- 1082-6068. ; 43:5, s. 512-525
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Tidskriftsartikel (refereegranskat)abstract
- When solutions of two different polymers are mixed, phase separation often occurs even at low concentrations of polymers. One polymer usually collects in one phase and the other polymer in the other phase. When water is used as solvent, two aqueous, immiscible, phases are obtained. The same holds for aqueous mixtures of a salt and a polymer. Such aqueous two-phase systems (ATPS) are very useful for separation of high-molecular-weight biomolecules such as proteins and nucleic acids and also for cells, cell organelles, and membrane vesicles. The phase systems can be made highly selective and they are also mild toward biomolecules and cell particles. In this review we describe how ATPS can be used for fragmentation and separation analyses of biological membranes and how this can be used for mapping of the photosynthetic membrane, the thylakoid, of green leaves.
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| 4. |
- Danielsson, Ravi, et al.
(författare)
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Dimeric and monomeric organization of photosystem II - Distribution of five distinct complexes in the different domains of the thylakoid membrane
- 2006
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 281:20, s. 14241-14249
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Tidskriftsartikel (refereegranskat)abstract
- The supramolecular organization of photosystem II (PSII) was characterized in distinct domains of the thylakoid membrane, the grana core, the grana margins, the stroma lamellae, and the so-called Y100 fraction. PSII supercomplexes, PSII core dimers, PSII core monomers, PSII core monomers lacking the CP43 subunit, and PSII reaction centers were resolved and quantified by blue native PAGE, SDS-PAGE for the second dimension, and immunoanalysis of the D1 protein. Dimeric PSII (PSII supercomplexes and PSII core dimers) dominate in the core part of the thylakoid granum, whereas the monomeric PSII prevails in the stroma lamellae. Considerable amounts of PSII monomers lacking the CP43 protein and PSII reaction centers (D1-D2-cytochrome b(559) complex) were found in the stroma lamellae. Our quantitative picture of the supramolecular composition of PSII, which is totally different between different domains of the thylakoid membrane, is discussed with respect to the function of PSII in each fraction. Steady state electron transfer, flash-induced fluorescence decay, and EPR analysis revealed that nearly all of the dimeric forms represent oxygen-evolving PSII centers. PSII core monomers were heterogeneous, and a large fraction did not evolve oxygen. PSII monomers without the CP43 protein and PSII reaction centers showed no oxygen-evolving activity.
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| 5. |
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| 6. |
- Danielsson, Ravi, et al.
(författare)
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Fragmentation and separation analysis of the photosynthetic membrane from spinach.
- 2009
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728. ; 1787:1, s. 25-36
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Tidskriftsartikel (refereegranskat)abstract
- Membrane vesicles, originating from grana, grana core (appressed grana regions), grana margins and stroma lamellae/end membranes, were analysed by counter current distribution (CCD) using aqueous dextran-polyethylene glycol two-phase systems. Each vesicle population gave rise to distinct peaks in the CCD diagram representing different vesicle subpopulations. The grana vesicles and grana core vesicles each separated into 3 different subpopulations having different chlorophyll a/b ratios and PSI/PSII ratios. Two of the grana core subpopulations had a chlorophyll a/b ratio of 2.0 and PSI/PSII ratio of 0.10 and are among the most PSII enriched thylakoid vesicle preparation obtained so far by a non detergent method. The margin vesicles separated into 3 different populations, with about the same chlorophyll a/b ratios, but different fluorescence emission spectra. The stroma lamellae/end membrane vesicles separated into 4 subpopulations. Plastoglobules, connected to membrane vesicles, were highly enriched in 2 of these subpopulations and it is proposed that these 2 subpopulations originate from stroma lamellae while the 2 others originate from end membranes. Fragmentation and separation analysis shows that the margins of grana constitute a distinct domain of the thylakoid and also allows the estimation of the chlorophyll antenna sizes of PSI and PSII in different thylakoid domains.
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| 7. |
- Danielsson, Ravi, et al.
(författare)
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Metabolic Reprogramming of Macrophages upon In Vitro Incubation with Aluminum-Based Adjuvant
- 2023
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 24:5
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum-based adjuvants have been extensively used in vaccines. Despite their widespread use, the mechanism behind the immune stimulation properties of these adjuvants is not fully understood. Needless to say, extending the knowledge of the immune-stimulating properties of aluminum-based adjuvants is of utmost importance in the development of new, safer, and efficient vaccines. To further our knowledge of the mode of action of aluminum-based adjuvants, the prospect of metabolic reprogramming of macrophages upon phagocytosis of aluminum-based adjuvants was investigated. Macrophages were differentiated and polarized in vitro from human peripheral monocytes and incubated with the aluminum-based adjuvant Alhydrogel((R)). Polarization was verified by the expression of CD markers and cytokine production. In order to recognize adjuvant-derived reprogramming, macrophages were incubated with Alhydrogel((R)) or particles of polystyrene as control, and the cellular lactate content was analyzed using a bioluminescent assay. Quiescent M0 macrophages, as well as alternatively activated M2 macrophages, exhibited increased glycolytic metabolism upon exposure to aluminum-based adjuvants, indicating a metabolic reprogramming of the cells. Phagocytosis of aluminous adjuvants could result in an intracellular depot of aluminum ions, which may induce or support a metabolic reprogramming of the macrophages. The resulting increase in inflammatory macrophages could thus prove to be an important factor in the immune-stimulating properties of aluminum-based adjuvants.
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| 8. |
- Danielsson, Ravi
(författare)
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On the lateral organisation of the thylakoid membrane
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this work the lateral heterogeneity of the thylakoid membrane was investigated by quantifying the amount of photosystem I (PSI), photosystem II (PSII) and some PSII complexes and PSII proteins in different domains of the thylakoid. Grana, grana core, grana margins and stroma lamellae + end fractions were obtained by sonication and separation in a non-detergent, aqueous polymer two-phase system. Y-100 was obtained by Yeda press and centrifugation. EPR spectroscopy was used to quantify PSI (P700+) and PSII (YD·) in the different fractions. These measurements showed a successively increasing amount of PSI from grana core, grana, grana margins and stroma lamellae + end membranes to Y-100. On the contrary the amount of PSII is decreased successively from grana core to Y-100. The ratio PSI/PSII increases from 0,25 in grana core to 13 in Y-100. For the entire thylakoid the PSI/PSII ratio is 1,13. Gel electrophoresis was performed to trace five PSII complexes (supercomplexes, dimers, monomers with CP43 and monomers without CP43, and core reaction centres) in the different fractions of the thylakoid. These were then quantified by western blotting. The supercomplexes are most common in grana core and the fragments of the complexes are most common in Y-100, in a gradient through the fractions. This gives strong support to the notion of a lateral transport of PSII centres from grana core to Y-100 and back again, in a repair process. Thirteen PSII proteins were also analysed and quantified in the different fractions. PsbS, PsbW, PsbZ were overrepresented in grana or grana core and absent or nearly absent in Y-100. It agrees with their assumed function of preserving and stabilising the fully developed PSII complexes in grana core. Using counter-current distribution, a diagram was obtained showing heterogeneity within all the sub-fractions according to their surface properties.
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| 9. |
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| 10. |
- Danielsson, Ravi, et al.
(författare)
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Quantification, of photosystem I and II in different parts of the thylakoid membrane from spinach
- 2004
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728. ; 1608:1, s. 53-61
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Electron paramagnetic resonance (EPR) was used to quantify Photosystem I (PSI) and PSII in vesicles originating from a series of well-defined but different domains of the thylakoid membrane in spinach prepared by non-detergent techniques. Thylakoids from spinach were fragmented by sonication and separated by aqueous polymer two-phase partitioning into vesicles originating from grana and stroma lamellae. The grana vesicles were further sonicated and separated into two vesicle preparations originating from the grana margins and the appressed domains of grana (the grana core), respectively. PSI and PSII were determined in the same samples from the maximal size of the EPR signal from P700(+) and Y-D(.), respectively. The following PSI/PSII ratios were found: thylakoids, 1.13; grana vesicles, 0.43; grana core, 0.25; grana margins, 1.28; stroma lamellae 3.10. In a sub-fraction of the stroma lamellae, denoted Y-100, PSI was highly enriched and the PSI/PSII ratio was 13. The antenna size of the respective photosystems was calculated from the experimental data and the assumption that a PSII center in the stroma lamellae (PSIIbeta) has an antenna size of 100 Ch1. This gave the following results: PSI in grana margins (PSIalpha) 300, PSI (PSIbeta) in stroma lamellae 214, PSII in grana core (PSIIalpha) 280. The results suggest that PSI in grana margins have two additional light-harvesting complex 11 (LHCII) trimers per reaction center compared to PSI in stroma lamellae, and that PSII in grana has four LHCII trimers per monomer compared to PSII in stroma lamellae. Calculation of the total chlorophyll associated with PSI and PSII, respectively, suggests that more chlorophyll (about 10%) is associated with PSI than with PSII. (C) 2003 Elsevier B.V. All rights reserved.
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| 11. |
- Danielsson, Ravi, et al.
(författare)
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Tracing Aluminium-based Adjuvants : Their Interactions with Immune Competent Cells and their Effect on Mitochondrial Activity
- 2018
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Ingår i: Open Immunology Journal. - : Bentham eBooks. - 1874-2262. ; 8, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies revealing the immune stimulatory properties of aluminium-based adjuvants (ABAs) have been impaired by the absence of simple and reliable methods of tracing the adjuvants and their effect on biochemical processes upon endocytosis. Objective: To verify that labelling of ABAs with lumogallion doesn’t affect the physicochemical properties of the adjuvant; tracing cellular interaction with aluminium adjuvants; explore their effect on metabolic activity upon endocytosis. Methods: Physicochemical characterization by Z-potential and size distribution of ABAs labelled with lumogallion. Cellular interactions with ABAs by flow cytometry and confocal microscopy. Metabolic activity explored by measuring transformation of tetrazolium into formazan. Results: No or minor change of zeta potential and average particle size of lumogallion labelled aluminium oxyhydroxide, AlO(OH) and aluminium hydroxyphosphate, Al(OH)x(PO4 )y. Both phagocytosing and non-phagocytosing leukocytes became associated with ABAs at concentrations expected after in vivo administration of a vaccine. The ABAs were relatively toxic, affecting both lymphocytes and monocytes, and Al(OH)x(PO4 )y was more toxic than AlO(OH). Endocytosed aluminium adjuvant particles were not secreted from the cells and remained intracellular throughout several cell divisions. The presence of ABAs increased the mitochondrial activity of the monocytic cell line THP-1 and peripheral monocytes, as based on the transformation of tetrazolium into formazan. Conclusion: Lumogallion labelled ABAs is a valuable tool tracing interactions between ABAs and cells. Labelled ABAs can be traced intracellularly and ABAs are likely to remain intracellular for a long period of time. Intracellular ABAs increase the mitochondrial activity and the presence of intracellular Al ions is suggested to cause an increased mitochondrial activity. Keywords: Aluminium based adjuvant, Lumogallion, Mitochondrial activity, MTT assay, Phagocytosis, ABAS, Zeolites.
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| 12. |
- Kirchhoff, Helmut, et al.
(författare)
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Low-light-induced formation of semicrystalline photosystem II arrays in higher plant chloroplast
- 2007
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 46:39, s. 11169-11176
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Tidskriftsartikel (refereegranskat)abstract
- Remodeling of photosynthetic machinery induced by growing spinach plants under low light intensities reveals an up-regulation of light-harvesting complexes and down-regulation of photosystem II and cytochrome b(6)f complexes in intact thylakoids and isolated grana membranes. The antenna size of PSII increased by 40-60% as estimated by fluorescence induction and LHCII/PSII stoichiometry. These low-light-induced changes in the protein composition were accompanied by the formation of ordered particle arrays in the exoplasmic fracture face in grana thylakoids detected by freeze-fracture electron microscopy. Most likely these highly ordered arrays consist of PSII complexes. A statistical analysis of the particles in these structures shows that the distance of neighboring complexes in the same row is 18.0 urn, the separation between two rows is 23.7 nm, and the angle between the particle axis and the row is 26 degrees. On the basis of structural information on the photosystem II supercomplex, a model on the supramolecular arrangement was generated predicting that two neighboring complexes share a trimeric light-harvesting complex. It was suggested that the supramolecular reorganization in ordered arrays in low-light grana thylakoids is a strategy to overcome potential diffusion problems in this crowded membrane. Furthermore, the occurrence of a hexagonal phase of the lipid monogalactosyldiacylglycerol in grana membranes of low-light-adapted plants could trigger the rearrangement by changing the lateral membrane pressure.
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| 13. |
- Mamedov, Fikret, et al.
(författare)
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EPR characterization of photosystem II from different domains of the thylakoid membrane
- 2008
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 47:12, s. 3883-3891
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Tidskriftsartikel (refereegranskat)abstract
- We report electron paramagnetic resonance (EPR) studies on photosystem, 11 (PSII) from higher plants in five different domains of the thylakoid membrane prepared by sonication and two-phase partitioning. The domains studied were the grana core, the entire grana stack, the grana margins, the stroma lamellae and the purified stromal fraction, Y100. The electron transport properties of both donor and acceptor sides of PSII such as oxygen evolution, cofactors Y-D, Q(A), the CaMn4-cluster, and Cytb559 were investigated. The PSII content was estimated on the basis of oxidized YD and Q(A)(_) Fe2+ signal from the acceptor side vs Chl content (100% in the grana core fraction). It was found to be about 82% in the grana, 59% in the margins, 35% in the stroma and 15% in the Y100 fraction. The most active PSH centers were found in the granal fractions as was estimated from the rates of electron transfer and the S-2 State multiline EPR signal. In the margin and stromal fractions the multiline signal was smaller (40 and 33%, respectively). The S2 state multiline could not be induced in the Y100 fraction. In addition, the oxidized LP Cytb559 prevailed in the stromal fractions while the HP form dominated in the grana core. The margins and entire grana fractions have Cytb559 in both potential forms. These data together with previous analyses indicate that the sequence of activation of the PSII properties can be represented as: PSII content > oxygen evolution > reduced Cytb559 > dimerization of PSII centers in all fractions of the thylakoid membrane with the gradual increase from stromal fractions via margin to the grana core fraction. The results further support the existence of a PSII activity gradient which reflects lateral movement and photoactivation of PSII centers in the thylakoid membrane. The possible role of the PSII redox components in this process is discussed.
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| 14. |
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| 15. |
- Ohlsson, Lars, et al.
(författare)
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Increased level of circulating cell-free mitochondrial DNA due to a single bout of strenuous physical exercise
- 2020
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 120, s. 897-905
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Physical exercise is reported to affect the immune response in various ways. Thus, the levels of pro-inflammatory cytokines as well as the abundance of circulating leukocytes are changed. In this study, the occurence of circulating cell-free mitochondrial DNA (cfmtDNA) and nuclear DNA (nDNA) was investigated in connection with a single bout of strenuous physical exercise. Methods Healthy volunteers performed a controlled ergo-spirometry cycle test and venous blood samples were taken at different time-points to analyze the concentration of blood components before, during and after the test. The number of circulating leukocytes was measured, as well as secretion of the soluble urokinase activator receptor (suPAR). Results Cf-mtDNA significantly increased during exercise, compared to baseline values and after 30 and 90 min of rest. Circulating leukocytes increased during exercise, but returned to baseline levels afterwards. Surface expression of the urokinase plasminogen activating receptor (uPAR) on neutrophils decreased significantly during exercise. The concentration of suPAR tended to increase during exercise but only significantly after 90 min of rest. Conclusion Increased concentration of cf-mtDNA indicates that cell damage takes place during high intensity training. Hypoxia and tissue damage are likely causes of cf-mtDNA from muscle cells. The levels of cf-mtDNA remain high during the initial rest, due to the decreasing numbers of leukocytes normally clearing the plasma from cf-mtDNA. The increased levels of suPAR further emphasize that strenuous physical exercise causes a reaction similar to inflammation. Further studies are needed to detect the source of increased cf-mtDNA and the corresponding increase of suPAR liberation.
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| 16. |
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| 17. |
- Suorsa, Marjaana, et al.
(författare)
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Dark-adapted spinach thylakoid protein heterogeneity offers insights into the photosystem II repair cycle
- 2014
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728 .- 1879-2650. ; 1837:9, s. 1463-1471
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Tidskriftsartikel (refereegranskat)abstract
- In higher plants, thylakoid membrane protein complexes show lateral heterogeneity in their distribution: photosystem (PS) II complexes are mostly located in grana stacks, whereas PSI and adenosine triphosphate (ATP) synthase are mostly found in the stroma-exposed thylakoids. However, recent research has revealed strong dynamics in distribution of photosystems and their light harvesting antenna along the thylakoid membrane. Here, the dark-adapted spinach (Spinacia oleracea L.) thylakoid network was mechanically fragmented and the composition of distinct PSII-related proteins in various thylakoid subdomains was analyzed in order to get more insights into the composition and localization of various PSII subcomplexes and auxiliary proteins during the PSII repair cycle. Most of the PSII subunits followed rather equal distribution with roughly 70% of the proteins located collectively in the grana thylakoids and grana margins; however, the low molecular mass subunits PsbW and PsbX as well as the PsbS proteins were found to be more exclusively located in grana thylakoids. The auxiliary proteins assisting in repair cycle of PSII were mostly located in stroma-exposed thylakoids, with the exception of THYLAKOID LUMEN PROTEIN OF 18.3 (TLP18.3), which was more evenly distributed between the grana and stroma thylakoids. The TL29 protein was present exclusively in grana thylakoids. Intriguingly, PROTON GRADIENT REGULATIONS (PGR5) was found to be distributed quite evenly between grana and stroma thylakoids, whereas PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE1 (PGRL1) was highly enriched in the stroma thylakoids and practically missing from the grana cores. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy. (C) 2013 Elsevier B.V. All rights reserved.
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| 18. |
- Tchekwagep, Patrick Marcel Seumo, et al.
(författare)
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Determination of Total Protein Concentration in Solution Using Gold Electrode Modified with Silver Nanoparticles
- 2015
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Ingår i: Electroanalysis. - : John Wiley & Sons. - 1040-0397 .- 1521-4109. ; 27:1, s. 253-257
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Tidskriftsartikel (refereegranskat)abstract
- Gold electrodes were modified with silver nanoparticles and Ag/AgCl redox conversion was recorded by cyclic voltammetry in protein containing electrolyte solution. The charge of the reduction peak decreased with the increase of the total protein concentration. This correlation was better for solutions containing bovine serum albumin as a standard than for the samples of human saliva. The results of these electroanalytical measurements show that the method can be used to determine protein concentration in electrolyte solution in the range from 0.01 to 0.2 mg mL(-1), though reproducibility of analysis of real samples must be further improved.
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| 19. |
- Tikkanen, Mikko, et al.
(författare)
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Phosphorylation-dependent regulation of excitation energy distribution between the two photosystems in higher plants
- 2008
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728 .- 1879-2650. ; 1777:5, s. 425-432
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorylation-dependent movement of the light-harvesting complex II (LHCII) between photosystern II (PSII) and photosystem I (PSI) takes place in order to balance the function of the two photosystems. Traditionally, the phosphorylatable fraction of LHCII has been considered as the functional unit of this dynamic regulation. Here, a mechanical fractionation of the thylakoid membrane of Spinacia oleracea was performed from leaves both in the phosphorylated state (low light, LL) and in the dephosphorylated state (dark, D) in order to compare the phosphorylation-dependent protein movements with the excitation changes occurring in the two photosystems upon LHCII phosphorylation, Despite the fact that several LHCII proteins migrate to stroma lamellae when LHCII is phosphorylated, no increase occurs in the 77 K fluorescence emitted from PSI in this membrane fraction. On the contrary, such an increase in fluorescence occurs in the grana margin fraction, and the functionally important mobile unit is the PSI-LHCI complex. A new model for LHCII phosphorylation driven regulation of relative PSII/PSI excitation thus emphasises an increase in PSI absorption cross-section occurring in grana margins upon LHCII phosphorylation and resulting from the movement of PSI-LHCI complexes from stroma lamellae and subsequent co-operation with the P-LHCII antenna from the grana. The grana margins probably give a flexibility for regulation of linear and cyclic electron flow in plant chloroplasts.
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| 20. |
- Abbafati, Cristiana, et al.
(författare)
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- 2020
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Tidskriftsartikel (refereegranskat)
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