| 1. |
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| 2. |
- Bergström, Ulf, et al.
(författare)
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Effects of Treatment with Adalimumab on Blood Lipid Levels and Atherosclerosis in Patients with Rheumatoid Arthritis
- 2018
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Ingår i: Current Therapeutic Research - Clinical and Experimental. - : Elsevier BV. - 0011-393X. ; 89, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Background: Treatment with tumor necrosis factor inhibitors for rheumatoid arthritis has been associated with a decreased risk of cardiovascular disease in observational studies. There are conflicting data on the influence of tumor necrosis factor inhibitors on lipid levels. Objectives: To evaluate the effect of treatment with adalimumab on blood lipid levels, lipoproteins, and atherosclerosis of the carotid artery. Methods: Fourteen patients with active rheumatoid arthritis (11 women and 3 men; mean age 63.7 years; median disease duration 9.0 years; and 78% rheumatoid factor positive) were treated with adalimumab 40 mg subcutaneously every 2 weeks and followed for 3 months. The patients had not been treated with adalimumab previously and had not received other tumor necrosis factor inhibitors within the past 3 months or moderate/high dose corticosteroids within the past 2 weeks. The intima-media thickness of the common carotid artery was assessed using B mode ultrasonography. Triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol levels were analyzed in fresh fasting blood samples, whereas apolipoprotein B and apolipoprotein A1 (apoA1) levels were determined in thawed plasma samples using standard turbidimetric immunoassays. Results: Total cholesterol (mean = 5.36 vs 5.96 mmol/L; P = 0.005), LDL cholesterol (mean = 3.33 vs 3.77 mmol/L; P =.005), HDL cholesterol (mean = 1.43 vs 1.55 mmol/L; P = 0.048), apolipoprotein B (mean = 1.04 vs 1.13 g/L; P =.012), and apoA1 (mean = 1.42 vs 1.58 g/L; P = 0.005) all increased, but there were no major changes in the LDL to HDL cholesterol ratio (median = 2.56 vs 2.35; P = 0.27) or the apolipoprotein B to apoA1 ratio (mean = 0.76 vs 0.74; P = 0.46). There was no change in triglyceride levels (P = 0.55). Disease activity decreased significantly from baseline to the 3-month evaluation (disease activity score based on 28 joints mean = 5.6 vs 4.1; P = 0.007). An increase in apoA1 correlated with decreases in the patient global assessment of disease severity (r = 0.79; P = 0.001) and C-reactive protein level (r = 0.74; P = 0.003). Changes in the apoliprotein B to apoA1 ratio correlated with changes in erythrocyte sedimentation rate (r = 0.54; P = 0.046). There was no major change in the common carotid artery intima-media thickness (mean = 0.78 vs 0.80 mm; P = 0.48). Conclusions: Although these results suggest that control of inflammation could have a beneficial effect on the lipid profile through an increase in HDL cholesterol levels, the observed protective effect on cardiovascular disease events by tumor necrosis factor blockers is likely to be explained by other mechanisms than changes in lipid levels or short-term effects on atherosclerosis of the carotid artery. © 2018 The Authors
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| 3. |
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Bergtagen
- 2020. - 200
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Samlingsverk (redaktörskap) (populärvet., debatt m.m.)
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| 4. |
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| 5. |
- Darracq, Amelie, et al.
(författare)
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Quantification of advective solute travel times and mass transport through hydrological catchments
- 2010
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Ingår i: Environmental Fluid Mechanics. - : Springer Science and Business Media LLC. - 1567-7419 .- 1573-1510. ; 10:1-2, s. 103-120
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Tidskriftsartikel (refereegranskat)abstract
- This study has investigated and outlined the possible quantification and mapping of the distributions of advective solute travel times through hydrological catchments. These distributions are essential for understanding how local water flow and solute transport and attenuation processes affect the catchment-scale transport of solute, for instance with regard to biogeochemical cycling, contamination persistence and water quality. The spatial and statistical distributions of advective travel times have been quantified based on reported hydrological flow and mass-transport modeling results for two coastal Swedish catchments. The results show that the combined travel time distributions for the groundwater-stream network continuum in these catchments depend largely on the groundwater system and model representation, in particular regarding the spatial variability of groundwater hydraulic parameters (conductivity, porosity and gradient), and the possible contributions of slower/deeper groundwater flow components. Model assumptions about the spatial variability of groundwater hydraulic properties can thus greatly affect model results of catchment-scale solute spreading. The importance of advective travel time variability for the total mass delivery of naturally attenuated solute (tracer, nutrient, pollutant) from a catchment to its downstream water recipient depends on the product of catchment-average physical travel time and attenuation rate.
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| 6. |
- Darracq, Amelie, et al.
(författare)
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Scale and model resolution effects on the distributions of advective solute travel times in catchments
- 2010
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Ingår i: Hydrological Processes. - : John Wiley & Sons, Ltd.. - 0885-6087 .- 1099-1085. ; 24:12, s. 1697-1710
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Tidskriftsartikel (refereegranskat)abstract
- Advective solute travel times and their distributions in hydrological catchments are useful descriptors of the dynamics and variation of the physical mass transport among and along the different source-to-recipient pathways of solute transport through the catchments. This article investigates the scale dependence and the effects of model and data resolution on the quantification of advective travel times and their distributions in the Swedish catchment areas of Norrström and Forsmark. In the surface water networks of the investigated (sub)catchments, the mean advective travel time increases with (sub)catchment scale, whereas the relative travel time variability around the mean value (coefficient of variation, CV) is scale-invariant and insensitive to model resolution. In the groundwater and for the whole (sub)catchments, both the mean value and the CV of travel times are scale-invariant, but sensitive to model resolution and accuracy. Such quantifications and results of advective travel times constitute important steps in the development of improved understanding and modelling of nutrient, pollutant and tracer transport through catchments.
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| 7. |
- Dawson, Lucas, et al.
(författare)
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Impacts of the Water Framework Directive on learning and knowledge practices in a Swedish catchment
- 2018
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Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 223, s. 731-742
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Tidskriftsartikel (refereegranskat)abstract
- Catchments are complex social-ecological systems involving multiple, and often competing, interests. Water governance and management regimes are increasingly embracing pluralistic, participatory, and holistic norms as a means to engage with issues of complexity, uncertainty, and value-conflicts. Integrated, participatory approaches are theoretically linked to improved learning amongst stakeholders across sectors and decision-making that is grounded in shared knowledge, experiences and scientific evidence. However, few studies have empirically examined the impacts of an integrated approach to learning and knowledge practices related to water resources.Here, a Swedish sub-catchment that has adopted such an approach in association with implementation of the European Water Framework Directive (WFD) is examined. Interview-based analyses show that WFD implementation has both helped and hindered learning and knowledge practices surrounding both water planning and spatial planning. Whilst communities of practice have developed in the study area, a number of important challenges remain. These include the rigid goal-orientation of the WFD, the fragmentation of knowledge caused by an over-reliance on external consultants, as well as a lack of resources to synthesise information from multiple sources. Present results raise questions regarding the efficacy of the WFD to sufficiently enable the development of learning and knowledge practices capable of handling the complexity, uncertainties and value-conflicts facing catchments in Sweden and elsewhere.
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| 8. |
- Destouni, Georgia, et al.
(författare)
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Lagrangian pathway-travel time theory and scenario analysis of tracer-pollutant and uncertainty propagation through catchments
- 2012
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Ingår i: Geophysical Research Abstracts, Vol. 14, EGU2012-6940, 2012.
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Konferensbidrag (refereegranskat)abstract
- This paper presents how tracer, nutrient and pollutant transport through a catchment can be analyzed based on mean flow and other flow-transport properties given or resolved by simulations, by following the trajectories (pathways) of transport through the catchment and the flow-transport property distribution among them. Convolution of relevant property distributions across consecutive hydrological units, aggregated over the trajectories that originate from the tracer/pollutant-specific injection area, captures hydrological dispersion with its basic measure derived as the travel time coefficient of variation. Various memory functions can be introduced in a relatively simple manner for incorporating retention/mass transfer mechanisms under conditions of statistical stationarity. The paper further shows how spatial and temporal flow variability can be accounted for in this general theory, and how each and both of these variability components influence hydrological transport in catchments. Moreover, the paper outlines how the theory can be used in a scenario analysis approach to quantify and map the effects of uncertainty in physical and biogeochemical characteristics on diffuse hydrological transport and its uncertainty
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Hellström, Gustav, et al.
(författare)
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GABAergic anxiolytic drug in water increases migration behaviour in salmon
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Migration is an important life-history event in a wide range of taxa, yet many migrations are influenced by anthropogenic change. Although migration dynamics are extensively studied, the potential effects of environmental contaminants on migratory physiology are poorly understood. In this study we show that an anxiolytic drug in water can promote downward migratory behaviour of Atlantic salmon (Salmo salar) in both laboratory setting and in a natural river tributary. Exposing salmon smolt to a dilute concentration of a GABAA receptor agonist (oxazepam) increased migration intensity compared with untreated smolt. These results implicate that salmon migration may be affected by human-induced changes in water chemical properties, such as acidification and pharmaceutical residues in wastewater effluent, via alterations in the GABAA receptor function.
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| 13. |
- Hevekerl, Heike, 1982-, et al.
(författare)
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Dark states in ionic oligothiophene bioprobes-evidence from fluorescence correlation spectroscopy and dynamic light scattering
- 2014
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 118:22, s. 5924--5933
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Tidskriftsartikel (refereegranskat)abstract
- Luminescent conjugated polyelectrolytes (LCPs) can upon interaction with biological macromolecules change their luminescent properties, and thereby serve as conformation- and interaction-sensitive biomolecular probes. However, to exploit this in a more quantitative manner, there is a need to better understand the photophysical processes involved. We report studies of the conjugated pentameric oligothiophene, derivative p-FTAA, which changes optical properties with different p-FTAA concentrations in aqueous buffers, and in a pH and oxygen saturation dependent manner. Using dynamic light scattering, luminescence spectroscopy and fluorescence correlation spectroscopy, we find evidence for a monomer dimer equilibrium, for the formation of large clusters of p-FTAA in aqueous environment, and can couple aggregation to changed emission properties of oligothiophenes. In addition, we observe the presence of at least two dark transient states, one presumably being a triplet state. Oxygen was found to statically quench the p-FTAA fluorescence but also to promote molecular fluorescence by quenching dark transient states of the p-FTAA molecules. Taken together, this study provides knowledge of fluorescence and photophysical features essential for applying p-FTAA and other oligothiophene derivatives for diagnostic purposes, including detection and staining of amyloid aggregates.
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| 14. |
- Ijumba, Petrida, 1951-
(författare)
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Intervention for improved newborn feeding and survival where HIV is common : Perceptions and effects of a community-based package for maternal and newborn care in a South African township
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- South Africa recently changed infant feeding policy within Prevention of Mother to Child Transmission (PMTCT) of HIV from free formula to recommendation of breastfeeding for all. The country is evaluating the role of Community Health Workers (CHWs) in supporting mothers and newborns.The aim of this thesis is to explore perceptions of household members on the value given to and the social forces behind formula feeding in light of the recent policy change, and to assess the effect of a community-based package of maternal and newborn care delivered by CHWs on HIV-free survival and exclusive and appropriate infant feeding up to 12 weeks of age.Studies were conducted in a high HIV prevalence township. Focus group discussions were performed (grandmothers, fathers and teenage mothers) and in-depth interviews with HIV-positive and HIV-negative mothers. Perceptions of household members on the formula policy change were explored and the value household members place on formula feeding and circumstances that drive it. In a cluster-randomized trial (15 intervention, 15 control clusters) CHWs provided two antenatal and five post-natal home visits to support and promote PMTCT activities.There were misunderstandings by community members on the free formula policy change. Mothers transferred the motherhood role to their mothers while partners provided inadequate financial support, leading to risky mixed feeding. Teenage mothers rarely breastfed their infants due to perceived constraints including embarrassment, sagging breasts and loss of freedom and boyfriends.At 12 weeks of age the intervention had doubled exclusive breastfeeding (EBF) (28% vs. 14%) and slightly increased infant weight and length. No difference was seen between study arms in HIV-free survival. The effect on EBF at12 weeks did not differ with maternal education or wealth levels, but was higher among HIV-negative mothers. Focusing on teenage mothers breastfeeding challenges, involvement of grandmothers and fathers in infant feeding decision-making, improving communication strategies on policy change and breastfeeding to the community and health workers and CHWs home visits supporting PMTCT activities are important for infant feeding and child health.
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| 15. |
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| 16. |
- Jarsjö, Jerker, et al.
(författare)
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Solute transport in coupled inland – coastal water systems : General conceptualisation and application to Forsmark
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We formulate a general theoretical conceptualisation of solute transport from inland sources to downstream recipients, considering main recipient load contributions from all different nutrient and pollutant sources that may exist within any catchment. Since the conceptualisation is model-independent, its main hydrological factors and mass delivery factors can be quantified on the basis of inputs to and outputs from any considered analytical or numerical model. Some of the conceptually considered source contribution and transport pathway combinations are however commonly neglected in catchment-scale solute transport and attenuation modelling, in particular those related to subsurface sources, diffuse sources at the land surface and direct groundwater transport into the recipient. The conceptual framework provides a possible tool for clarification of underlying and often implicit model assumptions, which can be useful for e.g. inter-model comparisons in SKB’s site investigation or safety assessment programmes. In order to further clarify and explain research questions that may be of particular importance for transport pathways from deep groundwater surrounding a repository, we concretise and interpret some selected transport scenarios for model conditions in the Forsmark area. Possible uncertainties in coastal discharge predictions (that underpin all transport results), related to uncertain spatial variation of evapotranspiration within the catchment, were shown to be small for the relatively large, focused surface water discharges from land to sea, because local differences were averaged out along the length of the main water flow paths. In contrast, local flux values within the diffuse groundwater flow field from land to sea are more uncertain, although estimates of mean values and total sums of submarine groundwater discharge (SGD) along some considerable coastline length may be robust. The present results show that 80% to 90% of the total coastal discharge of Forsmark occurred through focused flows in visible streams, whereas the remaining 10% to 20% was diffuse and occurring through submarine groundwater discharge (SGD), small transient streams and/ or coastal wetlands. Regarding transport quantifications, hydrogeochemical characteristics and pollution source loads may generally differ between larger, monitored catchments and smaller unmonitored coastal catchments. Since national hydrological monitoring data systematically exclude smaller, coastal catchments, they may not be representative for conditions in Forsmark (or Simpevarp). This emphasises the importance of extending in time the recently started hydrological and hydrogeochemical data series in the Forsmark and Simpevarp coastal catchment areas, since they are in effect unmonitored from a hydrological viewpoint, due to the lack of extended discharge time series. In the performed initial demonstration analysis of solute transport pathways from deep groundwater to recipients at the surface, we considered the main scenarios: (I) transport in the quaternary deposits/bedrock interface zone only (assuming that the deep groundwater transport pathway to the coast excludes the inland surface water system), and (II) transport in the coupled groundwater-surface water system. Considering mean travel times from each model cell to the coast, and disregarding travel times in the deep bedrock domain itself (which may be added to the here presented values), results show that travel times in scenario (II) were less than 4 years in 90% of the considered model area (i.e., the Forsmark catchment area). Travel times were longer in scenario (I) with values higher than 10 years in 40% of the catchment area. These results are based on the assumption that the pathways do not go through zones of near-stagnant groundwater (found e.g. below Lake Bolundsfjärden, Lake Eckarfjärden and Lake Gällsboträsket in Forsmark). If they would do so (and the above assumption is violated), results show that travel times can be considerably longer, for instance exceeding 400 years in half of the model area in scenario (I). Considering possible solute attenuation (caused by e.g. biogeochemical reactions or decay) along the hydrological transport pathways to inland surface waters and to the coast, we estimate solute mass delivery factors, representing the fraction of mass released in a cell that reaches the considered recipient. Results showed that average delivery factors, representing the whole catchment and equalling expected delivery factors in the probabilistic case, can exhibit considerable differences between transport pathway scenarios (I) and (II). However, the magnitude of the differences in average delivery factors (between transport pathway scenarios as well as between considered release points) depends on the actual attenuation rates (i.e., l-values). This is because for low l (for Forsmark: l<0.01 year-1), practically all mass reaches the coast regardless of release point and scenario, and for high l (for Forsmark: l>10 year-1) only a small fraction of the mass reaches the coast regardless of release point and scenario. The above results imply that, in general, mass delivery factors to recipients are sensitive to both pathways and entrance points or areas in the quaternary deposits of Forsmark, with for instance a remaining key question being to which extent the deep groundwater transport pathway to the coast includes the surface water system and /or quaternary deposits/bedrock interface zone. However, given more specific sub-catchment areas (e.g., of biosphere objects of interest) and possible ranges of attenuation rates (of compounds of interest) from parallel studies, the present analyses also show that robust predictions regarding e.g. mass delivery can in some cases be obtained despite considerable pathway and entrance point uncertainties. Because such cases then can be excluded from further investigation, it appears that specific transport analyses that considers relevant combinations of possible release points, transport pathway scenarios and attenuation rates can be used for delimiting specific priority regions, where remaining uncertainties are high and further experimental investigations and/or monitoring hence may be needed to reduce the uncertainties.
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| 17. |
- Karlsson, Isabella, 1980, et al.
(författare)
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Investigation of the Sunscreen Octocrylene's Interaction with Amino Acid Analogs in the Presence of UV Radiation
- 2012
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 88:4, s. 904-912
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Tidskriftsartikel (refereegranskat)abstract
- Octocrylene is an organic UV filter, commonly used in sunscreens and cosmetics, which can give rise to both contact and photocontact allergy. Our aim was to investigate octocrylenes interaction with amino acid analogs in the presence of UV radiation to better understand the reason for octocrylenes photoallergenic capacity. The amino acid analogs were photolysed in presence and absence of octocrylene for 1 h in cyclohexane. The rate of degradation was considerably slower for all amino acid analogs when octocrylene was present in the mixture. Benzylamine, the lysine analog, did react with octocrylene during the photolysis and the corresponding amide was formed in an acylation reaction. By varying the benzylamine concentration and keeping the octocrylene concentration fixed the reaction rate was shown to be independent of the amine concentration. The same type of acylation reaction took place when octocrylene alone was photolysed in ethanol in which the ethyl ester was formed from octocrylene and ethanol. Our results suggest that octocrylenes ability to cause photocontact allergy could be due to its photoinduced reactivity toward primary amines and alcohols.
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| 18. |
- Karlsson, Isabella, 1980, et al.
(författare)
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Ketoprofen-Induced Formation of Amino Acid Photoadducts: Possible Explanation for Photocontact Allergy to Ketoprofen
- 2014
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Ingår i: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 27:7, s. 1294-1303
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Tidskriftsartikel (refereegranskat)abstract
- Photocontact allergy is a well-known side effect of topical preparations of the nonsteroidal anti-inflammatory drug ketoprofen. Photocontact allergy to ketoprofen appears to induce a large number of photocross allergies to both structurally similar and structurally unrelated compounds. Contact and photocontact allergies are explained by structural modification of skin proteins by the allergen. This complex is recognized by the immune system, which initiates an immune response. We have studied ketoprofen's interaction with amino acids to better understand ketoprofen's photoallergenic ability. Irradiation of ketoprofen and amino acid analogues resulted in four different ketoprofen photodecarboxylation products (6-9) together with a fifth photoproduct (5). Dihydroquinazoline 5 was shown to be a reaction product between the indole moiety of 3-methylindole (Trp analogue) and the primary amine benzylamine (Lys analogue). In presence of air, dihydroquinazoline 5 quickly degrades into stable quinazolinone 12. The corresponding quinazolinone (17) was formed upon irradiation of ketoprofen and the amino acids N-acetyl-L-Trp ethyl ester and L-Lys ethyl ester. The formation of these models of an immunogenic complex starts with the ketoprofen-sensitized formation of singlet oxygen, which reacts with the indole moiety of Trp. The formed intermediate subsequently reacts with the primary amino functionality of Lys, or its analogue, to form a Trp Lys adduct or a mimic thereof. The formation of a specific immunogenic complex that does not contain the allergen but that can still induce photocontact allergy would explain the large number of photocross allergies with ketoprofen. These allergens do not have to be structurally similar as long as they can generate singlet oxygen. To the best of our knowledge, there is no other suggested explanation for ketoprofen's photoallergenic properties that can account for the observed photocross allergies. The formation of a specific immunogenic complex that does not contain the allergen is a novel hypothesis in the field of contact and photocontact allergy.
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| 19. |
- Lagesson, Annelie, et al.
(författare)
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No evidence of increased growth or mortality in fish exposed to oxazepam in semi-natural ecosystems
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 615, s. 608-614
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Tidskriftsartikel (refereegranskat)abstract
- An increasing number of short-term laboratory studies on fish reports behavioral effects from exposure to aquatic contaminants or raised carbon dioxide levels affecting the GABAAreceptor. However, how such GABAergic behavioral modifications (GBMs) impact populations in more complex natural systems is not known. In this study, we induced GBMs in European perch (Perca fluviatilis) via exposure to a GABA agonist (oxazepam) and followed the effects on growth and survival over one summer (70 days) in replicated pond ecosystems. We hypothesized that anticipated GBMs, expressed as anti-anxiety like behaviors (higher activity and boldness levels), that increase feeding rates in laboratory assays, would; i) increase growth and ii) increase mortality from predation. To test our hypotheses, 480 PIT tagged perch of known individual weights, and 12 predators (northern pike, Esox lucius) were evenly distributed in 12 ponds; six control (no oxazepam) and six spiked (15.5 ± 4 μg l− 1 oxazepam [mean ± 1 S.E.]) ponds. Contrary to our hypotheses, even though perch grew on average 16% more when exposed to oxazepam, we found no significant difference between exposed and control fish in growth (exposed: 3.9 ± 1.2 g, control: 2.9 ± 1 g [mean ± 1 S.E.], respectively) or mortality (exposed: 26.5 ± 1.8 individuals pond− 1, control: 24.5 ± 2.6 individuals pond− 1, respectively). In addition, we show that reduced prey capture efficiency in exposed pike may explain the lack of significant differences in predation. Hence, our results suggest that GBMs, which in laboratory studies impact fish behavior, and subsequently also feeding rates, do not seem to generate strong effects on growth and predation-risk in more complex and resource limited natural environments.
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| 20. |
- Lin, Hongzhen, et al.
(författare)
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Fate of Excitations in Conjugated Polymers : Single-Molecule Spectroscopy Reveals Nonemissive "Dark" Regions in MEH-PPV Individual Chains
- 2009
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:12, s. 4456-4461
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Tidskriftsartikel (refereegranskat)abstract
- Single chains of the conjugated polymer MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)) were studied with wide-field fluorescence microscopy (dispersion in inert polymer matrices) and with fluorescence correlation spectroscopy (chloroform solution). The fluorescence yield of individual molecules in matrices was found to be 1-2 orders of magnitude lower than that in solution and it decreased substantially with increasing chain length. It suggests that isolation of MEH-PPV molecules in polymer matrices creates favorable conditions for photogeneration of nonemissive primary excited states.
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| 21. |
- Liuba, Petru, et al.
(författare)
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Acute infections in children are accompanied by oxidative modification of LDL and decrease of HDL cholesterol, and are followed by thickening of carotid intima-media.
- 2003
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Ingår i: European Heart Journal. - 1522-9645. ; 24:6, s. 517-523
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Tidskriftsartikel (refereegranskat)abstract
- Background Atherosclerosis begins early in life. Infections might contribute to the pathogenesis of atherosclerosis. In this study, we investigated whether acute infections in children could alter the carotid wall morphology and the tipid profile. Methods Mean carotid intima-media thickness (IMT) was measured by high-resolution ultrasound in 28 hospitatised children (mean age: 5 2 years), who fulfilled the diagnostic criteria of acute infections (body temperature, >38 degreesC; C-reactive protein, >15 mg/ml, and clinical), and in 20 age- and gender-matched controls. Antibodies against oxidised tow-density lipoprotein (anti-oxLDL antibodies), as well as total and high-density lipoprotein cholesterol (HDL-C) were analysed in all children. The infection group was investigated both during the acute illness and 3 months after clinical recovery (post-infection). Results During the acute illness, the infection group had elevated anti-oxLDL antibodies and decreased HDL-C, as compared to those obtained at 3 months and in controls (p<0.05). These changes in the infection group were followed, at 3 months, by thickening of carotid intima-media. Those who received antibiotics during their acute illness had less carotid thickening than those who were not treated with antibiotics (p<0.05). Conclusion Acute infections in children seem to be accompanied by enhanced oxidative modification of LDL and by decrease in HDL-C. These lipid changes may be followed by thickening of carotid artery intima-media. These findings suggest that, in childhood, acute infections could be-associated with increased risk of atherosclerosis, and warrant further studies on this topic. (C) 2003 The European Society of Cardiology.
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| 22. |
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| 23. |
- Mangs, Sara, et al.
(författare)
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PET and PUR foam insulated District Heating Pipes – Study : Environmental Comparison
- 2006
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Ingår i: Euroheat & Power. - Zürich : Euroheat & Power. - 0949-166X. ; 3:1, s. 26-31
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The environmental performance of district heating (DH) pipes insulated with polyethylene terephthalate (PET) foams and pipes insulated with polyurethane (PUR) foam was discussed. It was found that carbon dioxide blown PET foam insulated DH pipes have the potential to compete successfully in terms of environmental performance with cyclopentane blown PUR foam insulated pipes provided that commercial methods to produce PET foam of lower density are developed. It was also found that the utilization of recycled PET can reduce the environmental impacts and would contribute to the efficient use of resources in society. The potential for improvement in the long-term thermal and environmental performance of PET is high.
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| 24. |
- Persson, Camilla, 1976-, et al.
(författare)
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Insulating performance of flexible pipes
- 2006
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Ingår i: 10th International Symposium on District Heating and Cooling.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 25. |
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| 26. |
- Persson, Gustav, et al.
(författare)
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Fluorescence cross-correlation spectroscopy of a pH-sensitive ratiometric dye for molecular proton exchange studies
- 2009
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - Cambridge, UK : RSC Publishing. - 1463-9076 .- 1463-9084. ; 11:21, s. 4410-4418
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence fluctuation analysis of individual pH-sensitive fluorophores has recently proven to be a useful approach for biomolecular proton exchange studies. In this work, dual-color fluorescence cross-correlation spectroscopy (FCCS) is demonstrated on a ratiometric pH-sensitive dye, for which both the excitation and emission spectra shift as a function of pH. In the FCCS measurements, the fluorescence signal from the predominant emission wavelength range of the protonated form of the dye is cross-correlated with that of the deprotonated form. Two lasers are used alternatingly to excite predominantly the protonated and the deprotonated form of the dye. The alternating excitation modulation scheme is combined with detection gating, and is based on a recently developed concept that allows extraction of correlation data for all correlation times regardless of the chosen modulation period. The scheme can thus be applied without concern for the time-scales of the molecular dynamic processes to be studied. By this combined discrimination based on both excitation and emission, spectral cross-talk is dramatically reduced and a very distinct and unambiguous anticorrelation can be recorded in the correlation curves as a consequence of the proton exchange. The strong discrimination power makes the approach applicable also to ratiometric dyes with less pronounced spectral shifts. It should also be useful in combination with ratiometric dyes sensitive to other ambient conditions and ions, such as the biologically very important calcium ion.
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| 27. |
- Persson, Gustav, et al.
(författare)
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Modulated Fluorescence Correlation Spectroscopy with Complete Time Range Information
- 2008
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Ingår i: Biophysical Journal. - Bethesda, MD : the Biophysical Society. - 0006-3495 .- 1542-0086. ; 94:3, s. 977-985
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Tidskriftsartikel (refereegranskat)abstract
- Two methods to combine fluorescence correlation spectroscopy (FCS) with modulated excitation, in a way that allows extraction of correlation data for all correlation times have been developed and experimentally verified. One method extracts distortion-free correlation data from measurements acquired with standard hardware correlators provided the fluorescence does not change systematically within the excitation pulses. This restriction does not apply to the second method, which, however, requires time-resolved acquisition of the fluorescence intensity. Modulation of the excitation in an FCS experiment is demonstrated to suppress triplet population buildup more efficiently than a corresponding reduction in continuous wave excitation intensity (shown for the dye rhodamine 6G in aqueous solution). Excitation modulation thus offers an additional means to optimize the FCS measurement conditions with respect to the photophysical properties of the dyes used. This possibility to suppress photoinduced states also provides a useful tool to distinguish additional processes occurring in the same time regime in the FCS measurements, as demonstrated here for the protonation kinetics of fluorescein at different pH. In general, the proposed concept opens for FCS measurements with a complete correlation timescale in a range of applications where a modulated excitation is either necessary or brings specific advantages.
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| 28. |
- Persson, Gustav, et al.
(författare)
-
Modulated or alternating excitation in fluorescence correlation spectroscopy
- 2009
-
Ingår i: SINGLE MOLECULE SPECTROSCOPY AND IMAGING. - : SPIE. - 9780819474315
-
Konferensbidrag (refereegranskat)abstract
- We have previously shown that formation of triplet states and other photo-induced states can be controlled by modulating the excitation with pulse widths and periods in the range of the transition times of the involved states. However, modulating the excitation in fluorescence correlation spectroscopy (FCS) measurements normally destroys correlation information and induces ringing in the correlation curve. We have introduced and experimentally verified a method to retrieve the full correlation curves from FCS measurements with modulated excitation and arbitrarily low fraction of active excitation. Modulated excitation applied to FCS experiments was shown to suppress the triplet build-up more efficiently than reducing excitation power with continuous wave excitation. The usefulness of the method was demonstrated by measurements done on fluorescein at different pH, where suppression of the triplet significantly facilitates the analysis of the protonation kinetics. Using a fluorophore where the protonation-coupled fluorescence intensity fluctuations are due to spectral shifts, introduction of two-color alternating excitation and spectral cross-correlation can turn the protonation component of the correlation curve into an anti-correlation and further facilitate the distinction of this component from those of other processes.
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| 29. |
- Persson, Gustav, et al.
(författare)
-
Modulation Filtering Enables Removal of Spikes in Fluorescence Correlation Spectroscopy Measurements without Affecting the Temporal Information
- 2009
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 113:25, s. 8752-8757
-
Tidskriftsartikel (refereegranskat)abstract
- The appearance of intensity spikes in measurements is a common problem in fluorescence correlation spectroscopy (FCS) studies of biological samples. In this work, we present a new method for generating artifact-free correlation curves from fluorescence traces that have undergone spike removal. This method preserves the temporal information throughout the measurement and properly represents the correlation between events separated by removed spikes. The method was validated using experimental data. The proposed algorithm is demonstrated herein to be generally applicable, but it is particularly powerful for cases where spikes occur frequently.
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| 30. |
- Persson, Gustav, 1977-
(författare)
-
Temporal Modulation in Fluorescence Spectroscopy and Imaging for Biological Applications
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis explores the benefits of intensity modulation for the purpose of extending the range of applications of fluorescence spectroscopy and imaging in cellular and molecular biology and medicine. Long-lived transient states of fluorescent molecules can, because of their long lifetimes, be used to detect subtle changes in the microenvironment of the molecule. A method for determining the kinetic rates for transitions to and from such states by registration of changes in the average fluorescence intensity related to different modulation of the excitation source is introduced. It combines the detection sensitivity of fluorescence with the environmental sensitivity of the long-lived transient states and allows the use of slow detectors such as CCD cameras, making parallelization and wide-field imaging possible developments. An extension of this method, generating image contrast based on triplet state population using a standard laser scanning microscope, is also shown. A strategy to combine fluorescence correlation spectroscopy (FCS) with modulated excitation, in a way that allows extraction of correlation data for all correlation times, is presented. This enables the use of modulation to optimize measurement conditions with respect to photophysical properties of the dyes used. FCS with modulated excitation will probably prove useful in future studies involving multiple kinetic processes occurring in overlapping time ranges. One of the ideas from this project also constitutes a powerful method for generating artifact free correlation curves from data sets where sections have been removed. This is potentially very useful in biological studies where spikes in the measurements often cause problems. In the final project, cross-correlation and alternating excitation are combined in measurements on a pH-sensitive ratiometric dye to clearly distinguish the protonation–deprotonation dynamics from other processes. The presented approach makes the protonation related fluctuations manifest themselves as a very distinct anti-correlating component in the correlation curve. This enables robust data analysis using a simple model.
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| 31. |
- Persson, Gustav, 1977-
(författare)
-
Time-Varying Excitation in Fluorescence Spectroscopy for Biological Applications
- 2007
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this thesis is to explore and use the benefits of time-varying excitation in fluorescence spectroscopy for studies of biomolecular dynamics. Two new techniques taking advantage of modulated excitation are presented. Also described are the first efforts in a project where single molecule FRET and multi-parameter fluorescence detection are used for characterization of the conformational dynamics of the retinoid X receptor (RXR). RXR is one of the most important proteins in the group of nuclear receptors. It is believed to be involved in many diseases and is hence most interesting as a potential drug target. Our study is at present at a very early stage and some sample issues are still to be resolved. However, single molecule measurements should give insights not attainable by previously applied ensemble methods and help explaining how RXR can regulate so many different processes. Long-lived transient states of fluorescent molecules can, because of their long lifetimes, be used to detect subtle changes in the microenvironment of the molecule. A method for determining the kinetic rates for transitions to and from such states by registration of changes in the average fluorescence intensity related to different modulation of the excitation source is introduced. It combines the sensitivity of fluorescence with the environmental sensitivity of the long-lived transient states and allows the use of slow detectors such as CCD cameras, making parallelization and imaging possible developments. The approach was experimentally verified by measurements of the triplet kinetics of rhodamine 6G (Rh6G) in aqueous solution and compared with fluorescence correlation spectroscopy (FCS). It should also be applicable to any other photoinduced transient states affecting the fluorescence intensity. A strategy to combine FCS with modulated excitation, in a way that allows extraction of correlation data for all correlation times, is presented. This enables the use of modulation to optimize the measurement conditions with respect to the photophysical properties of the dyes used. Measurements were made on Rh6G to verify the method. To illustrate its usefulness, it was applied to measurements of protonation kinetics of fluorescein at different pH. FCS with modulated excitation will most probably prove very useful in many future studies involving multiple kinetic processes occurring in overlapping time ranges.
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| 32. |
- Persson, Jerker
(författare)
-
Ultrasound and atherosclerosis. Evaluation of methods, risk factors and intervention.
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The importance of studying cardiovascular disease before the process leads to hard end-points has been recognised, and methods to quantify early atherosclerosis have been taken in use in many research centres around the world. An ultrasound method with a computer assisted image analysing system was developed in co-operation with the Wallenberg Laboratory for Cardiovascular Research and Chalmers University of Technology in Gothenburg, Sweden. The objectives of the studies were to determine the validity and reproducibility of the method, to describe the associations between known cardiovascular risk factors and as well ultrasound-determined degree of atherosclerosis cross-sectionally as progression of these parameters, and to elucidate the effects of multifactorial intervention on cardiovascular risk factors. The method proved valid and reproducible when evaluating early atherosclerosis, reflected by intima-media thickness (IMT) in the Carotid artery. Measurements of IMT in the Femoral artery and plaque size were less reproducible. In multiple regression models, ultrasound-determined degree of atherosclerosis cross-sectionally, as well as change in the degree, correlated to known cardiovascular risk factors with small differences between men and women. However, in general, the degrees of explanation were low in the multiple regression models, and the strongest determinator of progression in IMT, plaque occurrence and degree of stenosis were the baseline values, reflecting regression towards the mean. In a small pilot study, multifactorial intervention on cardiovascular risk factors resulted in no measurable effect on ultrasound-determined progression of atherosclerosis. Using the experience gained from our studies, the ultrasound method is well-suited for application in research on atherosclerosis progression and regression. In prospective studies, to avoid regression towards the mean, duplicate investigations at baseline and follow-up are recommended. In intervention studies, a more aggressive pharmacological treatment than what was the case in our study, should be applied after proper sample size calculations.
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| 33. |
- Persson, Klas, 1979-, et al.
(författare)
-
Diffuse hydrological mass transport through catchments : scenario analysis of coupled physical and biogeochemical uncertainty effects
- 2011
-
Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 15:10, s. 3195-3206
-
Tidskriftsartikel (refereegranskat)abstract
- This paper quantifies and maps the effects of coupled physical and biogeochemical variability on diffuse hydrological mass transport through and from catchments. It further develops a scenario analysis approach and investigates its applicability for handling uncertainties about both physical and biogeochemical variability and their different possible cross-correlation. The approach enables identification of conservative assumptions, uncertainty ranges, as well as pollutant/nutrient release locations and situations for which further investigations are most needed in order to reduce the most important uncertainty effects. The present scenario results provide different statistical and geographic distributions of advective travel times for diffuse hydrological mass transport. The geographic mapping can be used to identify potential hotspot areas with large mass loading to downstream surface and coastal waters, as well as their opposite, potential lowest-impact areas within the catchment. Results for alternative travel time distributions show that neglect or underestimation of the physical advection variability, and in particular of those transport pathways with much shorter than average advective solute travel times, can lead to substantial underestimation of pollutant and nutrient loads to downstream surface and coastal waters. This is particularly true for relatively high catchment-characteristic product of average attenuation rate and average advective travel time, for which mass delivery would be near zero under assumed transport homogeneity but can be orders of magnitude higher for variable transport conditions. A scenario of high advection variability, with a significant fraction of relatively short travel times, combined with a relevant average biogeochemical mass attenuation rate, emerges consistently from the present results as a generally reasonable, conservative assumption for estimating maximum diffuse mass loading, when the prevailing physical and biogeochemical variability and cross-correlation are uncertain.
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| 34. |
- Persson, Klas, 1979-, et al.
(författare)
-
Propagation of environmental risk from contaminant transport through groundwater and stream networks
- 2008
-
Ingår i: Risk Analysis VI.
-
Konferensbidrag (refereegranskat)abstract
- We use a Lagrangian stochastic advective-reactive (LaSAR) approach to model coupled groundwater and surface water contaminant transport. In this approach, physical (advective) solute travel time distributions constitute main functions for the contaminant transport representation. In a specific catchment area case study, we show how these travel time distributions, for separate groundwater and stream network systems and for the linked groundwater-stream systems of whole catchments, can be modelled and quantified from available field data. We further use the LaSAR modelling approach in an extreme-scenario methodology for investigating how the risk (probability) of concentrations exceeding given environmental or health-based concentration limits may propagate downstream of a contaminant source for various spatial source extents and contaminant release magnitudes and dynamics under different aquifer conditions. Results show that the average relation between characteristic advective transport and natural attenuation time scales is essential and in some (with results identifying also in which) cases sufficient information for assessing if and where this risk may decline below acceptable levels downstream of the source zone. The presented general quantification methodology and specific exemplification results may provide useful guidelines for emergency remediation of contaminated land sites and for prioritisation decisions and scoping calculations to focus further investigations of long-term remediation options on critical site and contaminant parameters. Keywords: contaminated land, solute transport, stochastic modelling, environmental risk analysis, GIS.
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| 35. |
- Persson, Klas, et al.
(författare)
-
Propagation of environmental risk from contaminant transport through groundwater and stream networks
- 2008
-
Ingår i: Risk analysis VI. ; , s. 55-64
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We use a Lagrangian stochastic advective-reactive (LaSAR) approach to model coupled groundwater and surface water contaminant transport. In this approach, physical (advective) solute travel time distributions constitute main functions for the contaminant transport representation. In a specific catchment area case study, we show how these travel time distributions, for separate groundwater and stream network systems and for the linked groundwater-stream systems of whole catchments, can be modelled and quantified from available field data. We further use the LaSAR modelling approach in an extreme-scenario methodology for investigating how the risk (probability) of concentrations exceeding given environmental or health-based concentration limits may propagate downstream of a contaminant source for various spatial source extents and contaminant release magnitudes and dynamics under different aquifer conditions. Results show that the average relation between characteristic advective transport and natural attenuation time scales is essential and in some (with results identifying also in which) cases sufficient information for assessing if and where this risk may decline below acceptable levels downstream of the source zone. The presented general quantification methodology and specific exemplification results may provide useful guidelines for emergency remediation of contaminated land sites and for prioritisation decisions and scoping calculations to focus further investigations of long-term remediation options on critical site and contaminant parameters.
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| 36. |
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| 37. |
- Persson, Klas, 1979-, et al.
(författare)
-
Riskkvantifiering vid föroreningsspridning genom avrinningsområden
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- För att skydda vattenresurserna inom ett avrinningsområde från förorening krävs uppskattningar både av den vattenburna föroreningsspridningen från alla befintliga föroreningskällor i området och av risken för framtida föroreningsutsläpp från nytillkomna källor (till följd av t.ex. föroreningsolyckor). I den här rapporten presenterar vi en metodik för beräkning av vattenburen föroreningsspridning från befintliga och tänkbara framtida föroreningskällor samt för uppskattning av tillhörande föroreningsrisk i termer av sannolikheten att givna gränsvärden för föroreningsnivåer överskrids i känsliga vattenmiljöer inom och nedströms ett avrinningsområde. Vi undersöker och illustrerar också metodikens användbarhet med beräkningsexempel från Forsmarks och Norrströms avrinningsområden. Den föreslagna metodiken utgörs av två beräkningssteg: I Steg 1 beräknas och karteras transporttider och transporttidsfördelningar för strömmande vatten, och vattenburna icke-reaktiva ämnen som helt följer vattnets rörelse, från olika föroreningskällor till känsliga grundvatten- och ytvattenmiljöer inom och nedströms avrinningsområdet. Resultat från detta första, ämnesoberoende steg kan användas för att identifiera de särskilt föroreningspåverkande delarna av ett avrinningsområde, varifrån utsläppta föroreningar snabbast kan spridas till en nedströms grundvatten- eller ytvattenrecipient med minst tidsutrymme för nedbrytning och andra självrenande processer längs spridningsvägarna. I Steg 2 beräknas och karteras den ämnesspecifika transporten av reaktiva föroreningar med vattnet, samt medföljande föroreningsrisker. Detta görs genom att de ämnesoberoende vattentransporttiderna och deras fördelning längs olika spridningsvägar, som beräknades i Steg 1, kopplas ihop med lämpliga modellbeskrivningar av nedbrytning och andra självreningsprocesser (som avklingning av radioaktiva ämnen och avskiljning av närsalter och metaller ur det strömmande vattnet) för olika specifika ämnen, eller grupper av ämnen med liknande processegenskaper. Våra resultat visar att det i detta beräkningssteg är viktigt att räkna med hela fördelningen av olika möjliga transporttider som kan förekomma från källa till recipient vid beräkning av vattenburen föroreningstransport. Om man bara räknar med en genomsnittlig transporttid kommer man att systematiskt underskatta den totala föroreningsmassa som når recipienten. Beräkningsosäkerheter, vad gäller karakteriseringen av föroreningskällor, vattenflöden och ämnesspridningen med vattnet, hanteras också i den föreslagna metodiken, genom sannolikhetsbaserade känslighetsanalyser. Dessa omfattar både statistisk representation av den slumpmässiga parametervariation som naturliga system ofta uppvisar samt olika antagna scenarier för nuvarande eller framtida förhållanden vars osäkerhet inte kan uppskattas i statistiska termer. På så vis kan man relativt enkelt bedöma hur stora osäkerheterna är och identifiera de intervall av spridningsförhållanden och ämnesspecifika självreningsegenskaper där osäkerheterna har stor praktisk betydelse för vattenförvaltning i ett avrinningsområde, samt de resterande, ofta bredare intervall där de inte har det. I det sistnämnda fallet får man, trots osäkerheterna, genom känslighetsanalysen en relativt säker och robust grund för beslut om exempelvis olycksberedskap och åtgärder för att begränsa föroreningsspridning från befintliga föroreningskällor. Genom att klart identifiera de fall där osäkerheterna spelar stor praktisk roll får man också ett rationellt underlag för att i dessa fall välja mellan att antingen göra fler undersökningar för att minska osäkerheterna, eller bedöma föroreningsriskerna konservativt och agera efter det sämsta av alla möjliga scenarier i vattenförvaltning, åtgärdsprogram och olycksberedskap.
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| 38. |
- Persson, Klas, 1979-, et al.
(författare)
-
Waterborne spreading of pollutants through hydrological catchments : a general approach to its quantification
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In order to protect water resources from contamination, it is necessary to assess the waterborne spreading of contaminants, both from all existing sources of pollution and from potential new sources (as a consequence of, for example, management changes and accidents or incidents that lead to discharge of pollutants). In this paper we adopt an approach that has previously been mostly used to quantify solute transport in soil and groundwater systems. Here, we develop the approach and apply it at the catchment scale for the estimation of waterborne contaminant spreading and the related risk for contamination of sensitive water environments within and downstream from a catchment area. The proposed approach consists of two calculation steps: (1) calculation and mapping of travel times and travel time distributions for flowing water, and waterborne non-reactive substances that directly follow the movement of the water, from identified or potential sources of pollution to sensitive downstream waters, and (2) the previously estimated travel time distributions are used for calculation and mapping of the transport of specific reactive pollutants with the water, and of the related risks for contamination of sensitive water environments. In the two calculation steps, random variability of transport properties and processes is represented statistically, while a scenario analysis is used to account for uncertainty about present or future conditions that cannot be quantified in statistical terms (e.g. uncertainties related to the characterisation of the sources of pollution, the water flow, and the transport of substances with the water). Through this approach one can relatively easily assess how large the uncertainties are, and identify those intervals of transport conditions and substance-specific mass attenuation properties for which the uncertainties are of great practical significance for water management in a catchment area, as well as the remaining intervals for which they are not of such significance. In cases where the uncertainties are found to be of minor importance from a management point of view, the scenario analysis provides a relatively robust basis on which to make decisions concerning, for example, urban planning, emergency preparedness and the appropriate measures to reduce the spreading of contaminants. Also, by clearly identifying the cases for which the uncertainties are of great practical significance, one obtains a rational basis on which to assess the value of further investigations in order to reduce the uncertainties.
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| 39. |
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| 40. |
- Sandén, Tor, et al.
(författare)
-
Monitoring Kinetics of Highly Environment Sensitive States of Fluorescent Molecules by Modulated Excitation and Time-Averaged Fluorescence Intensity Recording
- 2007
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 79:9, s. 3330-3341
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a concept is described for how the kinetics of photoinduced, transient, long-lived, nonfluorescent or weakly fluorescent states of fluorophore marker molecules can be extracted from the time-averaged fluorescence by using time-modulated excitation. The concept exploits the characteristic variation of the population of these states with the modulation parameters of the excitation and thereby circumvents the need for time resolution in the fluorescence detection. It combines the single-molecule sensitivity of fluorescence detection with the remarkable environmental responsiveness obtainable from long-lived transient states, yet does not in itself impose any constraints on the concentration or the fluorescence brightness of the sample molecules that can be measured. Modulation of the excitation can be performed by variation of the intensity of a stationary excitation beam in time or by repeated translations of a CW excitation beam with respect to the sample. As a first experimental verification of the approach, we have shown how the triplet-state parameters of the fluorophore rhodamine 6G in different aqueous enviroments can be extracted. We demonstrate that the concept is fully compatible with low time-resolution detection by a CCD camera. The concept opens for automated transient-state monitoring or imaging on a massively parallel scale and for high-throughput biomolecular screening as well as for more fundamental biomolecular studies. The concept should also be applicable to the monitoring of a range of other photoinduced nonfluorescent or weakly fluorescent transient states, from which subtle changes in the immediate microenvironment of the fluorophore marker molecules can be detected
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| 41. |
- Sandén, Tor, et al.
(författare)
-
Transient State Imaging for Microenvironmental Monitoring by Laser Scanning Microscopy
- 2008
-
Ingår i: Analytical Chemistry. - Washington, DC : American Chemical Society. - 0003-2700 .- 1520-6882. ; 80:24, s. 9589-9596
-
Tidskriftsartikel (refereegranskat)abstract
- Photoinduced transient dark states are exhibited by practically all common fluorophores. These relatively long-lived states are very sensitive to the local environment and thus highly attractive for microenvironmental imaging purposes. However, because of methodological constraints, their sensitivity has to date been very sparsely exploited. Here, a concept based on spatio-temporal modulation of the excitation intensity is presented that can image these states via their photodynamic fingerprints. With the use of a standard laser scanning microscope, it unites the outstanding environmental sensitivity of the transient state parameters with the high sensitivity of the fluorescence readout and is easily implemented. For demonstration, triplet state images of liposomes with different internal environments were generated. These images provide an example of bow local environmental differences can be resolved, which are not clearly distinguishable via other fluorescence parameters. Having minor instrumental and sample constraints the concept can be foreseen to provide several new, useful, and independent fluorescence-based parameters in biomolecular imaging.
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| 42. |
- Sanden, Tor, et al.
(författare)
-
Transient state microscopy : a new tool for biomolecular imaging
- 2009
-
Ingår i: MULTIPHOTON MICROSCOPY IN THE BIOMEDICAL SCIENCES IX. - Bellingham, WA : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819474292
-
Konferensbidrag (refereegranskat)abstract
- Photoinduced transient dark states are exhibited by practically all common fluorophores. However, their information content has to date only been sparsely exploited due to methodological constraints. Here, a new concept is presented and verified that can monitor and image these states via their photodynamic fingerprints. It unites the environmental sensitivity of these states with the sensitivity of fluorescence-based detection. For demonstration, triplet state images of liposomes in different environments were generated, showing how local environmental differences can be resolved, not clearly distinguishable via other fluorescence parameters. The concept can provide several new, useful and independent fluorescence-based parameters in biomolecular imaging.
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| 43. |
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| 44. |
- Thorslund, Josefin, et al.
(författare)
-
Wetlands as large-scale nature-based solutions : Status and challenges for research, engineering and management
- 2017
-
Ingår i: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 108, s. 489-497
-
Tidskriftsartikel (refereegranskat)abstract
- Wetlands are often considered as nature-based solutions that can provide a multitude of services of great social, economic and environmental value to humankind. Changes in land-use, water-use and climate can all impact wetland functions and services. These changes occur at scales extending well beyond the local scale of an individual wetland. However, in practical applications, engineering and management decisions usually focus on individual wetland projects and local site conditions. Here, we systematically investigate if and to what extent research has addressed the large-scale dynamics of landscape systems with multiple wetlands, hereafter referred to as wetlandscapes, which are likely to be relevant for understanding impacts of regional to global change. Although knowledge in many cases is still limited, evidence suggests that the aggregated effects of multiple wetlands in the landscape can differ considerably from the functions observed at individual wetland scales. This applies to provisioning of ecosystem services such as coastal protection, biodiversity support, groundwater level and soil moisture regulation, flood regulation and contaminant retention. We show that parallel and circular flow-paths, through which wetlands are interconnected in the landscape, may largely control such scale-function differences. We suggest ways forward for addressing the mismatch between the scales at which changes take place and the scale at which observations and implementation are currently made. These suggestions can help bridge gaps between researchers and engineers, which is critical for improving wetland function-effect predictability and management.
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| 45. |
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| 46. |
- Wigenius, Jens A., 1975-, et al.
(författare)
-
Dark states in oligothiophenes : evidence from fluorescence correlation spectroscopy and dynamic light scattering
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We report studies of the conjugated pentameric oligothiophene derivative p-FTAA, which changes optical properties in aqueous buffers of varying pH and concentration. Using dynamic light scattering, luminescence spectroscopy and fluorescence correlation spectroscopy, we find evidence for the formation of large clusters of p-FTAA in aqueous environment, formation of very large non-emissive clusters, and the presence of at least two dark transient states, one presumably being a triplet state. The clustering of p-FTAA is therefore an important mechanism. This work provides an interpretation of fluorescence spectra used for the detection of misfolding proteins through interaction with p-FTAA.
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| 47. |
- Wigenius, Jens A., 1975-, et al.
(författare)
-
Interactions Between a Luminescent Conjugated Oligoelectrolyte and Insulin During Early Phases of Amyloid Formation
- 2011
-
Ingår i: Macromolecular Bioscience. - : Wiley. - 1616-5187 .- 1616-5195. ; 11:8, s. 1120-1127
-
Tidskriftsartikel (refereegranskat)abstract
- Aggregates of misfolded proteins play an important role in diseases such as Alzheimer's. Here it is demonstrated how the anionic oligothiophene p-FTAA interacts with and influences pre-fibrillar protein assemblies during the earlier stages of in vitro fibrillation. Conjugated polythiophenes have previously been demonstrated to detect and discriminate between different types of protein aggregates and also introduce luminescent or conductive properties to these nanoscale fiber structures. Fluorescence spectroscopy, DLS, TEM and FCS are employed to follow the interplay between p-FTAA and insulin during in vitro fibrillation.
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