| 1. |
- Andersson, Agneta, et al.
(författare)
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Predators and nutrient availability favor protozoa-resisting bacteria in aquatic systems
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The long co-existence of bacteria and protozoa has led to the development of bacterial protozoa resistance strategies, which are suggested to serve as drivers for the evolution of pathogenic bacteria. However, the ecological mechanisms underpinning selection for protozoa-resistance in aquatic bacteria are poorly known. To assess the role of nutrient availability and predation-pressure on selection for protozoa-resisting bacteria (PRB), an enrichment-dilution experiment was designed using laboratory microcosms containing natural lake water. PRB was monitored by screening 16S rRNA amplicon sequence data for reads assigned to bacteria that previously has been shown to resist degradation by amoebae. To estimate the effects of the microbial food web dynamics (microscopy of; heterotrophic bacteria, phytoplankton, protozoa and rotifers) and physicochemical variables on the PRB abundance in the study system, a joint species distribution modelling approach was used. The predation-pressure (ratio between predator and bacterial biomass) had a positive effect on the abundance of the PRB genus Mycobacterium, while perturbation (enrichment and dilution) favored the PRB genus Pseudomonas that dominated the bacterial community in the disturbed systems. Our results show that PRB with different ecological strategies can be expected in water of high and intermediate nutrient levels and after major disturbances of an aquatic system.
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| 2. |
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| 3. |
- Backman, Agneta, et al.
(författare)
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Degradation of 4-chlorophenol at low temperature and during extreme temperature fluctuations by Arthrobacter chlorophenolicus A6
- 2004
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 48:2, s. 246-253
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Tidskriftsartikel (refereegranskat)abstract
- Low average temperatures and temperature fluctuations in temperate soils challenge the efficacy of microbial strains used for clean up of pollutants. In this study, we investigated the cold tolerance of Arthrobacter chlorophenolicus A6, a microorganism previously shown to degrade high concentrations of 4-chlorophenol at 28degreesC. Luciferase activity from a luc-tagged derivative of the strain (A6L) was used to monitor the metabolic status of the population during 4-chlorophenol degradation. The A6L strain could degrade 200-300 mug mL(-1) 4-chlorophenol in pure cultures incubated at 5degreesC, although rates of degradation, growth and the metabolic status of the cells were lower at 5degreesC compared to 28degreesC. When subjected to temperature fluctuations between 5 and 28degreesC, A6L continued to degrade 4-chlorophenol and remained active. In soil microcosm experiments, the degradation rates were significantly faster the first week at 28degreesC, compared to 5degreesC. However, this difference was no longer seen after 7 days, and equally low 4-chlorophenol concentrations were reached after 17 days at both temperatures. During 4-chlorophenol degradation in soil, CFU and luciferase activity values remained constant at both 5 and 28degreesC. However, once most of the 4-chlorophenol was degraded, both values decreased by 1-1.5 logarithmic values at 28degreesC, whereas they remained constant at 5degreesC, indicating a high survival of the cells at low temperatures. Because of the ability of A. chlorophenolicus A6 to degrade high concentrations of 4-chlorophenol at 5degreesC, together with its tolerance to temperature fluctuations and stress conditions found in soil, this strain is a promising candidate for bioaugmentation of chlorophenol-contaminated soil in temperate climates.
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| 4. |
- Backman, Agneta, et al.
(författare)
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Impact of temperature on the physiological status of a potential bioremediation inoculant, Arthrobacter chlorophenolicus A6
- 2004
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 70:5, s. 2952-2958
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Tidskriftsartikel (refereegranskat)abstract
- Arthrobacter chlorophenolicus A6 (A6) can degrade large amounts of 4-chlorophenol in soil at 5 and 28degreesC. In this study, we investigated the effects of temperature on the physiological status of this bacterium in pure culture and in soil. A derivative of A6 tagged with the gfp gene (encoding green fluorescent protein [GFP]) was used to specifically quantify A6 cells in soil. In addition, cyano-ditolyl-tetrazoliumchloride was used to stain GFP-fluorescent cells with an active electron transfer system ("viable cellis") whereas propidium iodide (PI) was used to stain cells with damaged membranes ("dead cells"). Another derivative of the strain (tagged with the firefly luciferase gene [luc]) was used to monitor the metabolic activity of the cell population, since the bioluminescence phenotype is dependent on cellular energy reserves. When the cells were incubated in soil at 28degreesC, the majority were stained with PI, indicating that they had lost their cell integrity. In addition, there was a corresponding decline in metabolic activity and in the ability to be grown in cultures on agar plates after incubation in soil at 28degreesC, indicating that the cells were dying under those conditions. When the cells were incubated in soil at 5degreesC, by contrast, the majority of the cells remained intact and a large fraction of the population remained metabolically active. A similar trend towards better cell survival at lower temperatures was found in pure-culture experiments. These results make A. chlorophenolicus A6 a good candidate for the treatment of chlorophenol-contaminated soil in cold climates.
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| 5. |
- Backman, Sara, et al.
(författare)
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Material Wear of Polymeric Tracheostomy Tubes : A Six-Month Study
- 2009
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Ingår i: The Laryngoscope. - : Wiley. - 0023-852X .- 1531-4995. ; 119:4, s. 657-664
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The objectives were to study long-term material wear of tracheostomy tubes made of silicone (Si), polyvinyl chloride (PVC), and polyurethane (PU) after 3 and 6 months of clinical use. Study Design: The study has a prospective and comparative design. Methods: Nineteen patients with long-term tracheostomy, attending the National Respiratory Center in Sweden, were included, n = 6 with Si tubes, n = 8 with PVC tubes, and n = 5 with PU tubes. The tubes were exposed to the local environment, in the trachea for 3 and 6 months and analyzed by scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and differential scanning calorimetry. Results: All tubes revealed severe surface changes. No significant differences were established after 3 or 6 months of exposure between the various materials. The changes had progressed significantly after this period, compared to previously reported changes after 30 days of exposure. The results from all analyzing techniques correlated well. Conclusions: All tubes, exposed in the trachea for 3-6 months, revealed major degradation and changes in the surface of the material. Polymeric tracheostomy tubes should be changed before the end of 3 months of clinical use.
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| 6. |
- Bourdieu, Pierre, et al.
(författare)
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Leve idrottspedagogiken : En vänbok tillägnad Lars-Magnus Engström
- 2005
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Vem ägnar sig åt idrott? Vilken betydelse har fritiden i barns och ungdomars liv? Vad innebär hälsa i skolämnet idrott och hälsa?Leve idrottspedagogiken! tillägnas Lars-Magnus Engström. Texterna i boken speglar delar av det idrottspedagogiska forskningsområdet i Sverige, vars framväxt Lars-Magnus Engström varit den främste företrädaren för. Läsaren får här ta del av exempelvis idrottskulturen, fritidskulturen och skolans ämne idrott och hälsa. Genomgående handlar texterna om villkoren för barns och ungdomars deltagane och om de olika lärprocesser som sker i anslutning till idrottsutövning.Lars-Magnus Engström har gjort betydande insatser som forskare och lärare samt som professor vid Lärarhögskolan i Stockholm och vid Gymnastik- och idrottshögskolan. I snart fyrtion år har han arbetat med studier kring påverkans- och lärprocesser i idrott. Hans forskning har främst kretsat kring människors idrottsvanor och vilka som utvecklar en fysiskt aktiv livsstil. Idrotts- och motionsutövningar ger både ett så kallat egenvärde och investeringsvärde. Med dessa begrepp bland många andra har Lars-Magnus Engström bidragit till en fördjupad vetenskaplig förståelse av idrottskulturen.De flesta författarna har eller har haft Lars-Magnus Engström som handledare och tillhör forskningsgruppen för pedagogik, idrott och fritidskultur. Redaktörer för boken är Karin Redelius och Håkan Larsson.
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| 7. |
- Fardell, Camilla, et al.
(författare)
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S100B polymorphisms are associated with age of onset of Parkinson's disease
- 2018
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Ingår i: Bmc Medical Genetics. - : Springer Science and Business Media LLC. - 1471-2350. ; 19:42
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Tidskriftsartikel (refereegranskat)abstract
- Background: In this study we investigated the association between SNPs in the S100B gene and Parkinson's disease (PD) in two independent Swedish cohorts. The SNP rs9722 has previously been shown to be associated with higher S100B concentrations in serum and frontal cortex in humans. S100B is widely expressed in the central nervous system and has many functions such as regulating calcium homeostasis, inflammatory processes, cytoskeleton assembly/disassembly, protein phosphorylation and degradation, and cell proliferation and differentiation. Several of these functions have been suggested to be of importance for the pathophysiology of PD. Methods: The SNPs rs9722, rs2239574, rs881827, rs9984765, and rs1051169 of the S100B gene were genotyped using the KASPar (R) PCR SNP genotyping system in a case-control study of two populations (431 PD patients and 465 controls, 195 PD patients and 378 controls, respectively). The association between the genotype and allelic distributions and PD risk was evaluated using Chi-Square and Cox proportional hazards test, as well as logistic regression. Linear regression and Cox proportional hazards tests were applied to assess the effect of the rs9722 genotypes on age of disease onset. Results: The S100B SNPs tested were not associated with the risk of PD. However, in both cohorts, the T allele of rs9722 was significantly more common in early onset PD patients compared to late onset PD patients. The SNP rs9722 was significantly related to age of onset, and each T allele lowered disease onset with 4.9 years. In addition, allelic variants of rs881827, rs9984765, and rs1051169, were significantly more common in early-onset PD compared to late-onset PD in the pooled population. Conclusions: rs9722, a functional SNP in the 3'-UTR of the S100B gene, was strongly associated with age of onset of PD.
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| 8. |
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| 9. |
- Larsson, Jonna, et al.
(författare)
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Undersökande Läsaktiviteter om Naturvetenskap
- 2022
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Ingår i: Praktiknära skolforskning FND 2022.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Detta samverkansprojekt har utvecklat en modell för undersökande läsaktiviteter i förskola och F-1 för att fördjupa barns meningsskapande om naturvetenskapliga innehåll i bilderböcker. Utifrån barns perspektiv och ett barnperspektiv på fysikaliska fenomen och kemiska processer i bilderböcker har den målinriktade undervisningen innefattat högläsning, samtal och lekbaserat undersökande om naturvetenskap. Syftet med detta paper är beskriva hur projektet undersökande läsaktiviteter om naturvetenskap har bidragit till att skapa förutsättningar för barn och elever att utveckla förståelse för fysikaliska fenomen och kemiska processer. Teoretiskt antar projektet ett kulturhistoriskt perspektiv, där förskolan, förskoleklassen och skolan framträder som kulturella praktiker. Barns lärande och utveckling förstås som processer av förändrat deltagande i de sammanhang som barn ingår i. Metodologiskt tar studien utgångspunkt i ett utvecklingspedagogiskt ramverk där barnperspektiv och barns perspektiv är centralt. Studiens tentativa resultat visar att förskollärare och lärare har utvecklat en mer differentierad bild av barns kunskaper. De undersökande läsaktiviteterna har bidragit till förändringar i såväl barns agerande som kommunicerande om naturvetenskapliga innehåll. Vidare framstår designen av de undersökande läsaktiviteterna samt studiens explicita fokus på naturvetenskapliga fenomen, i både bilderböcker och i vardagen, som bidragande till att barn blir mer delaktiga i undervisningen. Projektet har inneburit att förskollärare och lärare har utvecklat sin kompetens gällande att närma sig barns perspektiv i planering och genomförande av undervisning med fokus på naturvetenskapliga fenomen. Vidare har de identifierat att innehållets ’vad och varför’ påverkar ’hur’ läsaktiviteter och utforskande kan genomföras tillsammans med barn.
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| 10. |
- Maraha, Ninwe, et al.
(författare)
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Monitoring physiological status of GFP-tagged Pseudomonas fluorescens SBW25 under different nutrient conditions and in soil by flow cytometry
- 2004
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 51:1, s. 123-132
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Tidskriftsartikel (refereegranskat)abstract
- Pseudomonas fluorescens SBW25, a plant growth promoting bacterium. has been widely studied due to its potential as an inoculum for improving crop yields. Environmental inoculants are usually applied oil seeds or directly to soil and to effectively promote plant growth they need to be viable and active. However, it is difficult to study the physiological status of specific microorganisms in complex environments, such as soil. In this study, our aim was to use molecular tools to specifically monitor the physiological status of P. fluorescens SBW25 in soil and ill pure cultures incubated under different nutritional conditions. The cells were previously tagged with marker genes (encoding green fluorescent protein and bacterial luciferase) to specifically track the cells in environmental samples. The physiological status of the cells was determined using the viability stains 5-cyano-2,3-ditolyl-tetrazolium chloride (CTC) and propidium iodide (PI), which stain active and dead cells, respectively. Luciferase activity was used to monitor the metabolic activity of the population. Most of the cells died after incubation for nine days in nutrient rich medium. By contrast when incubated under starvation conditions, most of the population was not stained with CTC or PI (i.e. intact but inactive cells), indicating that most of the cells were presumably dormant. In soil, a large fraction of the SBW25 cell population became inactive and died, as determined by a decline in luciferase activity and CTC-stained cells, an increase in PI-stained cells, and an inability of the cells to be cultured oil agar medium. However, approximately 60% of the population was unstained, presumably indicating that the cells entered a state of dormancy in soil similar to that observed under starvation conditions in pure cultures. These results demonstrate the applicability of this approach for monitoring the physiological status of specific cells under stress conditions, such as those experienced by environmental inoculants in soil.
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| 11. |
- Strandkvist, Viktor, et al.
(författare)
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Hand grip strength is associated with fatigue among men with COPD : epidemiological data from northern Sweden
- 2020
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Ingår i: Physiotherapy Theory and Practice. - : Taylor & Francis. - 0959-3985 .- 1532-5040. ; 36:3, s. 408-416
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate if hand grip strength (HGS) is associated with: 1) fatigue, and specifically clinically relevant fatigue (CRF); 2) low physical activity; and 3) fatigue independent of physical activity level, among individuals with and without COPD. Data were collected from the Obstructive Lung Disease in Northern Sweden (OLIN) COPD-study in 2014. HGS was measured with a hand-grip dynamometer, fatigue and physical activity were assessed by questionnaires; FACIT-Fatigue respectively IPAQ. Among individuals with COPD (n = 389), but not without COPD (n = 442), HGS was lower among those with CRF than those without CRF, significantly so among men (p = 0.001) and close to among women (p = 0.051). HGS was not associated with physical activity levels within any of the groups. HGS was associated with fatigue among men, but not women, with COPD independent of physical activity level, age, height, and smoking habits (Beta = 0.190, 95% CI 0.061-0.319, respectively Beta = 0.048, 95% CI-0.056-0.152), while there were no corresponding significant findings among individuals without COPD. In summary, HGS was associated with CRF among individuals with COPD in this population-based study. Among men with COPD, HGS was associated with fatigue independent of physical activity level and common confounders.
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| 12. |
- Strandkvist, Viktor, et al.
(författare)
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Postural control among individuals with and without chronic obstructive pulmonary disease: A cross-sectional study of motor and sensory systems
- 2023
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 18:4
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundChronic obstructive pulmonary disease (COPD) is considered a heterogenic syndrome with systemic effects, including muscle dysfunction. There is evidence of postural control impairments among individuals with COPD, partly related to muscle weakness. However, research is scarce regarding the other underlying systems of postural control, such as the visual, somatosensory and vestibular system. The aim was to compare postural control, as well as the motor and sensory systems, between individuals with and without COPD.MethodsTwenty-two participants with COPD (mean age 74.0 ±6.2 years) and 34 non-obstructive references (mean age 74.9 ±4.9 years) participated in this cross-sectional study. Postural control was assessed with center of pressure trajectory of postural sway in quiet as well as a limits of stability test, calculating mediolateral and anteroposterior amplitudes for each test. Assessment of function in the motor system included maximum hand grip strength, as well as maximum strength in muscles around the hip, knee and ankle joints. Visual acuity, pressure sensibility, proprioception, vestibular screening, and reaction time were also included. Data was compared between groups, and significant differences in postural control were further analyzed with an orthogonal projection of latent structures regression model.ResultsThere was a significantly increased sway amplitude in the mediolateral direction in quiet stance on soft surface with eyes open (p = 0.014) as well as a smaller anteroposterior amplitude in the limits of stability test (p = 0.019) in the COPD group. Regression models revealed that the mediolateral amplitude was related to visual acuity and the burden of tobacco smoking assessed as pack-years. Further, muscle strength associated with anteroposterior amplitude in limits of stability test in the COPD group, and with age and ankle dorsal flexion strength among the referents. Besides for lower ankle plantar flexion strength in the COPD group, there were however no significant differences in muscle strength.ConclusionsIndividuals with COPD had a decreased postural control and several factors were associated with the impairments. The findings imply that the burden of tobacco smoking and reduced visual acuity relate to increased postural sway in quiet stance, and that muscle weakness is related to decreased limits of stability, among individuals with COPD.
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