3141. |
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3142. |
- Johnning, Anna, 1985, et al.
(författare)
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Quinolone resistance mutations in the faecal microbiota of Swedish travellers to India
- 2015
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: International travel contributes to the spread of antibiotic resistant bacteria over the world. Most studies addressing travel-related changes in the faecal flora have focused on specific mobile resistance genes, or depended on culturing of individual bacterial isolates. Antibiotic resistance can, however, also spread via travellers colonized by bacteria carrying chromosomal antibiotic resistance mutations, but this has received little attention so far. Here we aimed at exploring the abundance of chromosomal quinolone resistance mutations in Escherichia communities residing in the gut of Swedish travellers, and to determine potential changes after visiting India. Sweden is a country with a comparably low degree of quinolone use and quinolone resistance, whereas the opposite is true for India. Methods: Massively parallel amplicon sequencing targeting the quinolone-resistance determining region of gyrA and parC was applied to total DNA extracted from faecal samples. Paired samples were collected from 12 Swedish medical students before and after a 4-15 week visit to India. Twelve Indian residents were included for additional comparisons. Methods known resistance mutations were common in Swedes before travel as well as in Indians, with a trend for all mutations to be more common in the Indian sub group. There was a significant increase in the abundance of the most common amino acid substitution in GyrA (S83L, from 44 to 72 %, p = 0.036) in the samples collected after return to Sweden. No other substitution, including others commonly associated with quinolone resistance (D87N in GyrA, S80I in ParC) changed significantly. The number of distinct genotypes encoded in each traveller was significantly reduced after their visit to India for both GyrA (p = 0.0020) and ParC (p = 0.0051), indicating a reduced genetic diversity, similar to that found in the Indians. Conclusions: International travel can alter the composition of the Escherichia communities in the faecal flora, favouring bacteria carrying certain resistance mutations, and, thereby, contributes to the global spread of antibiotic resistance. A high abundance of specific mutations in Swedish travellers before visiting India is consistent with the hypothesis that these mutation have no fitness cost even in the absence of an antibiotic selection pressure.
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3143. |
- Johnning, Anna, 1985, et al.
(författare)
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Resistance Mutations in gyrA and parC are Common in Escherichia Communities of both Fluoroquinolone-Polluted and Uncontaminated Aquatic Environments
- 2015
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Alterations in the target proteins of fluoroquinolones, especially in GyrA and ParC, are known to cause resistance. Here, we investigated environmental Escherichia communities to explore the possible link between the abundance of mutations, and the exposure to fluoroquinolones. Sediment samples were collected from a relatively pristine lake, up and downstream from a sewage treatment plant, and from several industrially polluted sites. The quinolone resistance-determining regions of gyrA and parC were analyzed using amplicon sequencing of metagenomic DNA. Five non-synonymous substitutions were present in all samples, and all of these mutations have been previously linked to fluoroquinolone resistance in Escherichia coli. In GyrA, substitutions S83L and D87N were on average detected at frequencies of 86 and 32%, respectively, and 31% of all amplicons encoded both substitutions. In ParC, substitutions S80I, E84G, and E84V were detected in 42, 0.9, and 6.0% of the amplicons, respectively, and 6.5% encoded double substitutions. There was no significant correlation between the level of fluoroquinolone pollution and the relative abundance of resistance mutations, with the exception of the most polluted site, which showed the highest abundance of said substitutions in both genes. Our results demonstrate that resistance mutations can be common in environmental Escherichia, even in the absence of a fluoroquinolone selective pressure.
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3144. |
- Johnning, Anna, 1985, et al.
(författare)
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The resistomes of six carbapenem-resistant pathogens - a critical genotype-phenotype analysis
- 2018
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Ingår i: Microbial Genomics. - : Microbiology Society. - 2057-5858. ; 4:11
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Tidskriftsartikel (refereegranskat)abstract
- Carbapenem resistance is a rapidly growing threat to our ability to treat refractory bacterial infections. To understand how carbapenem resistance is mobilized and spread between pathogens, it is important to study the genetic context of the underlying resistance mechanisms. In this study, the resistomes of six clinical carbapenem-resistant isolates of five different species - Acinetobacter baumannii, Escherichia colt, two Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa - were characterized using whole genome sequencing. All Enterobacteriaceae isolates and the A. baumannii isolate had acquired a large number of antimicrobial resistance genes (7-18 different genes per isolate), including the following encoding carbapenemases: bla(KPC-2), bla(OXA-48), bla(OXA-72), bla(NDM-1), bla(NDm-7) and bla(VIM-1). In addition, a novel version of bla(SHv) was discovered. Four new resistance plasmids were identified and their fully assembled sequences were verified using optical DNA mapping. Most of the resistance genes were colocalized on these and other plasmids, suggesting a risk for coselection. In contrast, five out of six carbapenemase genes were present on plasmids with no or few other resistance genes. The expected level of resistance - based on acquired resistance determinants - was concordant with measured levels in most cases. There were, however, several important discrepancies for four of the six isolates concerning multiple classes of antibiotics. In conclusion, our results further elucidate the diversity of carbapenemases, their mechanisms of horizontal transfer and possible patterns of co-selection. The study also emphasizes the difficulty of using whole genome sequencing for antimicrobial susceptibility testing of pathogens with complex genotypes.
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3145. |
- Johnson, Mats, 1956, et al.
(författare)
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Fatty acids in ADHD: plasma profiles in a placebo-controlled study of Omega 3/6 fatty acids in children and adolescents.
- 2012
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Ingår i: Attention Deficit and Hyperactivity Disorders. - : Springer Science and Business Media LLC. - 1866-6116 .- 1866-6647. ; 4:4, s. 199-204
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess baseline levels and changes in plasma fatty acid profiles in children and adolescents with ADHD, in a placebo-controlled study with Omega 3/6 supplementation, and to compare with treatment response. Seventy-five children and adolescents aged 8-18 years with DSM-IV ADHD were randomized to 3 months of Omega 3/6 (Equazen eye q) or placebo, followed by 3 months of open phase Omega 3/6 for all. n-3, n-6, n-6/n-3 ratio, EPA and DHA in plasma were measured at baseline, 3 and 6 months. Subjects with more than 25 % reduction in ADHD symptoms were classified as responders. At baseline, no significant differences in mean fatty acid levels were seen across active/placebo groups or responder/non-responder groups. The 0-3 month changes in all parameters were significantly greater in the active group (p < 0.01). Compared to non-responders, the 6-month responders had significantly greater n-3 increase at 3 months and decrease in n-6/n-3 ratio at 3 and 6 months (p < 0.05). Omega 3/6 supplementation had a clear impact on fatty acid composition of plasma phosphatidyl choline in active versus placebo group, and the fatty acid changes appear to be associated with treatment response. The most pronounced and long-lasting changes for treatment responders compared to non-responders were in the n-6/n-3 ratio.
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3146. |
- Johnson, Mats, 1956, et al.
(författare)
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Omega 3/6 fatty acids for reading in children: a randomized, double-blind, placebo-controlled trial in 9-year-old mainstream schoolchildren in Sweden
- 2017
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Ingår i: Journal of Child Psychology and Psychiatry and Allied Disciplines. - : Wiley. - 0021-9630 .- 1469-7610. ; 58:1, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- Background Previous research has shown positive effects of Omega 3/6 fatty acids in children with inattention and reading difficulties. We aimed to investigate if Omega 3/6 improved reading ability in mainstream schoolchildren. Methods We performed a 3-month parallel, randomized, double-blind, placebo-controlled trial followed by 3-month active treatment for all subjects. Mainstream schoolchildren aged 9–10 years were randomized 1:1 to receive three Omega 3/6 capsules twice daily or identical placebo. Assessments were made at baseline, 3 months, and 6 months. The primary outcome measure was the Logos test battery for evaluating reading abilities. The trial is registered with ClinicalTrials.gov, number NCT02557477. Results The study enrolled 154 children (active n = 78; placebo n = 76), of whom 122 completed the first 3 months (active n = 64; placebo n = 58) and 105 completed the whole study (active/active n = 55; placebo/active n = 50). Outcomes were assessed by per protocol (PP) and intention-to-treat (ITT) analyses. Active treatment was superior to placebo at 3 months for improvement in phonologic decoding time (PP active/placebo difference −0.16; 95% CI −0.03, −0.29; effect size (ES) .44; p = .005; and ITT ES .37; p = .036), in visual analysis time (PP active/placebo difference −0.19; 95% CI −0.05, −0.33; ES .49; p = .013; and ITT ES .40; p = .01), and for boys in phonologic decoding time (PP −0.22; 95% CI −0.03, −0.41; ES .62; p = .004). Children with ADHD-RS scores above the median showed treatment benefits in visual analysis time (PP ES .8, p = .009), reading speed per word (PP ES .61, p = .008), and phonologic decoding time per word (PP ES .85, p = .006). Adverse events were rare and mild, mainly stomach pain/diarrhea (active n = 9, placebo n = 2). Conclusions Compared with placebo, 3 months of Omega 3/6 treatment improved reading ability – specifically the clinically relevant ‘phonologic decoding time’ and ‘visual analysis time’ – in mainstream schoolchildren. In particular, children with attention problems showed treatment benefits.
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3147. |
- Johnson, Mats, 1956, et al.
(författare)
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Open-label trial of atomoxetine hydrochloride in adults with ADHD.
- 2010
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Ingår i: Journal of Attention Disorders. - : SAGE Publications. - 1087-0547 .- 1557-1246. ; 13:5, s. 539-545
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Tidskriftsartikel (refereegranskat)abstract
- Background: While atomoxetine is an established treatment for attention-deficit/hyperactivity disorder in children, few studies have examined its efficacy for adults. Methods: Open-label trial of atomoxetine in 20 individuals with ADHD, aged 19-47 years, for 10 weeks, and a total of one year for responders. Results: Ten patients met primary efficacy criteria at 10 weeks. Only one patient completed the whole study. Six patients discontinued before 10 weeks and thirteen at 10 weeks or later, mainly because of side-effects (aggression, depressed mood, raised liver enzymes, thyroid hormones, diastolic blood pressure), decreasing efficacy or non-compliance. Conclusion: Fifty percent responded to treatment, but only one patient (5%) felt sufficient improvement to continue for one year. Dosage may have been too low, and baseline impairment too high, for atomoxetine to have sufficient effect on ADHD symptoms in our group of adults. The majority had few side-effects, but several terminated treatment because of adverse effects.
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3148. |
- Johnsson, Anna, 1975, et al.
(författare)
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Bioligand-mediated partitioning of radionuclides to the aqueous phase
- 2008
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 277:3, s. 637-644
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Tidskriftsartikel (refereegranskat)abstract
- The aqueous-phase partitioning of 59Fe, 147Pm, 234Th and 241Am by complexing compounds from subsurface bacteria has previously been studied in the presence of quartz sand. In this study the aqueous-phase partitioning of pico- to submicromolar amounts of 59Fe, 147Pm, 234Th and 241Am was analyzed in the presence of TiO2 and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. TiO2, with BET surface area of 49.9 m2·g-1, was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After incubation, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation method. Two types of values were calculated: solution% = the activity maintained in solution relative to the total activity, and Q-values = the quotient between the activity in samples and the activity in controls. Aerobic supernatants had solution% values between 89% and 100% for 59Fe and between 18 and 43% for 234Th. The solution% values for 241Am and 147Pm were less than 2% overall, but the Q-values were between 34 and 115 times more 241Am in bacterial supernatants than in controls. The corresponding values for 147Pm ranged from 6 to 20 times more than in the control. The solution% values for all elements in the presence of anaerobic supernatants were below 2%, but the Q-values clustered around 7 for 59Fe and ranging from 2 to 29 for 234Th, indicated that anaerobic supernatants partitioned these elements to the aqueous phase. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed, using the Chrome Azurol S assay. Complexation with excreted organic ligands is most likely the reason for the higher amounts of metals in samples than in the controls. Hence, aerobically and anaerobically excreted organic ligands seem able to influence the mobility of radionuclides in aerobic and anaerobic environments contaminated with these compounds.
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3149. |
- Johnsson, Anna, 1975, et al.
(författare)
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Leaching of spent nuclear fuel in the presence of siderophores
- 2009
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 279:2, s. 619-626
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Tidskriftsartikel (refereegranskat)abstract
- Metal species that are dissolved in water can be transported in the environment, because they can be mobile. Microorganisms can affect metal mobility by excreting organic ligands with high metal affinity. Siderophores are organic ligands with high affinities for Fe 3+ . They are also able to form complexes with other metals such as actinides. Many countries plan to deposit spent nuclear fuel in deep geological repositories. Microorganisms are present in these subterranean environments and could potentially affect the repository. In this study, the effect of microbial siderophores on the dissolution behavior of two fragments of a spent nuclear fuel pellet was investigated. The commercial hydroxamate siderophore, deferoxamine mesylate (DFAM), and pyoverdin siderophores, isolated from cultures of Pseudomonas fluorescens (CCUG 32456A), were used. DFAM and lyophilized pyoverdins were dissolved in synthetic groundwater to final concentrations of 10 μM and 2.5·10 -2 g·L -1 , respectively. The fuel pellet fragments were kept in sealed pressure vessels at 10 bars of H 2 . The pyoverdin solution was first tested, followed by the DFAM solution and the pure synthetic groundwater. Samples were taken on 0, 1, 5, 9 and 14 days after changing the solution in the pressure vessels. The elemental composition of samples was analyzed by means of ICP-MS. The pyoverdin solution maintained significantly higher concentrations of Np and Pu than the pure synthetic groundwater. On the 14 th day the concentrations of Np and Pu in the pure synthetic groundwater were 0.01 nM and 0.13 nM, respectively, compared to 0.02 nM and 0.31 nM in the pyoverdin solution. Furthermore, spent nuclear fuel samples were observed to release Ru in the presence of both pyoverdin and DFAM. Hence, it seems that siderophores can form complexes with elements present in spent nuclear fuel. © 2008 Akadémiai Kiadó.
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3150. |
- Johnsson, Anna, 1975, et al.
(författare)
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Solid-aqueous phase partitioning of radionuclides by complexing compounds excreted by subsurface bacteria
- 2006
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Ingår i: Geomicrobiology Journal. - : Informa UK Limited. - 0149-0451 .- 1521-0529. ; 23(8), s. 621-630
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Tidskriftsartikel (refereegranskat)abstract
- Radionuclides are present in numerous aerobic and anaerobic subsurface environments due to nuclear weapons testing, leakage from process and storage facilities, and discharge of radioactive waste. The partitioning of radionuclides between liquid and solid phases by complexing compounds excreted by subsurface bacteria was studied. The solid-aqueous phase partitioning of pico- to submicromolar amounts of 59 Fe, 147 Pm, 234 Th, and 241 Am was analyzed in the presence of quartz sand and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions, and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. Quartz sand, with a Brunauer, Emmett, and Teller (BET) surface area of 0.1 m 2 g -1 , was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After centrifuging, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation. Relative to the control, aerobic supernatants maintained more than 50% of the added 59 Fe, 234 Th, and 241 Am. The highest amount of metal present in the liquid phase of the anaerobic supernatants was found in the case of 241 Am, with 40% more 241 Am in samples than in controls. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed using the Chrome Azurol S assay. The great amounts of radionuclides in the liquid phases of samples were likely due to complexation with such compounds. Bacterially excreted complexing compounds hence seem able to influence the solid-aqueous phase partitioning of radionuclides. This could influence the mobility of radionuclides in contaminated subsurface environments.
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