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| 2. |
- Ahlinder, Jon, et al.
(författare)
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Upstream land use with microbial downstream consequences : iron and humic substances link to Legionella spp
- 2024
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 256
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Tidskriftsartikel (refereegranskat)abstract
- Intensified land use can disturb water quality, potentially increasing the abundance of bacterial pathogens, threatening public access to clean water. This threat involves both direct contamination of faecal bacteria as well as indirect factors, such as disturbed water chemistry and microbiota, which can lead to contamination. While direct contamination has been well described, the impact of indirect factors is less explored, despite the potential of severe downstream consequences on water supply. To assess direct and indirect downstream effects of buildings, farms, pastures and fields on potential water sources, we studied five Swedish lakes and their inflows. We analysed a total of 160 samples in a gradient of anthropogenic activity spanning four time points, including faecal and water-quality indicators. Through species distribution modelling, Random Forest and network analysis using 16S rRNA amplicon sequencing data, our findings highlight that land use indirectly impacts lakes via inflows. Land use impacted approximately one third of inflow microbiota taxa, in turn impacting ∌20–50 % of lake taxa. Indirect effects via inflows were also suggested by causal links between e.g. water colour and lake bacterial taxa, where this influenced the abundance of several freshwater bacteria, such as Polynucleobacter and Limnohabitans. However, it was not possible to identify direct effects on the lakes based on analysis of physiochemical- or microbial parameters. To avoid potential downstream consequences on water supply, it is thus important to consider possible indirect effects from upstream land use and inflows, even when no direct effects can be observed on lakes. Legionella (a genus containing bacterial pathogens) illustrated potential consequences, since the genus was particularly abundant in inflows and was shown to increase by the presence of pastures, fields, and farms. The approach presented here could be used to assess the suitability of lakes as alternative raw water sources or help to mitigate contaminations in important water catchments. Continued broad investigations of stressors on the microbial network can identify indirect effects, avoid enrichment of pathogens, and help secure water accessibility.
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| 3. |
- Dwibedi, Chinmay Kumar, et al.
(författare)
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Biological amplification of low frequency mutations unravels laboratory culture history of the bio-threat agent Francisella tularensis
- 2020
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 45
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Tidskriftsartikel (refereegranskat)abstract
- Challenges of investigating a suspected bio attack include establishing if microorganisms have been cultured to produce attack material and to identify their source. Addressing both issues, we have investigated genetic variations that emerge during laboratory culturing of the bacterial pathogen Francisella tularensis. Key aims were to identify genetic variations that are characteristic of laboratory culturing and explore the possibility of using biological amplification to identify genetic variation present at exceedingly low frequencies in a source sample. We used parallel serial passage experiments and high-throughput sequencing of F. tularensis to explore the genetic variation. We found that during early laboratory culture passages of F. tularensis, gene duplications emerged in the pathogen genome followed by single-nucleotide polymorphisms in genes for bacterial capsule synthesis. Based on a biological enrichment scheme and the use of high-throughput sequencing, we identified genetic variation that likely pre-existed in a source sample. The results support that capsule synthesis gene mutations are common during laboratory culture, and that a biological amplification strategy is useful for linking a F. tularensis sample to a specific laboratory variant among many highly similar variants.
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| 5. |
- Golovliov, Igor, 1958-, et al.
(författare)
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Long-Term Survival of Virulent Tularemia Pathogens outside a Host in Conditions That Mimic Natural Aquatic Environments
- 2021
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Ingår i: Applied and Environmental Microbiology. - : Elsevier. - 0099-2240 .- 1098-5336. ; 87:6, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Francisella tularensis, the causative agent of the zoonotic disease tularemia, can cause seasonal outbreaks of acute febrile illness in humans with disease peaks in late summer to autumn. Interestingly, its mechanisms for environmental persistence between outbreaks are poorly understood. One hypothesis is that F. tularensis forms biofilms in aquatic environments. We utilized two fully virulent wild-type strains: FSC200 (Francisella tularensis subsp. holarctica) and Schu S4 (Francisella tularensis subsp. tularensis) and three control strains, the attenuated live vaccine strain (LVS; F. tularensis subsp. holarctica), a Schu S4 DwbtI mutant that is documented to form biofilms, and the low-virulence strain U112 of the closely related species Francisella novicida. Strains were incubated in saline solution (0.9% NaCl) microcosms for 24 weeks at both 4°C and 20°C, whereupon viability and biofilm formation were measured. These temperatures were selected to approximate winter and summer temperatures of fresh water in Scandinavia, respectively. U112 and Schu S4 DwbtI formed biofilms, but F. tularensis strains FSC200 and Schu S4 and the LVS did not. All strains exhibited prolonged viability at 4°C compared to 20°C. U112 and FSC200 displayed remarkable long-term persistence at 4°C, with only 1- and 2-fold log reductions, respectively, of viable cells after 24weeks. Schu S4 exhibited lower survival, yielding no viable cells by week 20. At 24weeks, cells from FSC200, but not from Schu S4, were still fully virulent in mice. Taken together, these results demonstrate biofilm-independent, long-term survival of pathogenic F. tularensis subsp. holarctica in conditions that mimic overwinter survival in aquatic environments.
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| 7. |
- Granberg, Malin, et al.
(författare)
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Sick pay, health and work
- 2006
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Rapport (populärvet., debatt m.m.)abstract
- The purpose of this paper is to analyze the effects of different sickness insurance regimes on the employee decision reporting sick or not. We can think of the design problem as a representative employer’s decision to determine the optimal relationship between the wage and the sickness pay. The employee bases her decision to work or not on this relative price and her exogenously given health status that varies between individuals. We believe that the incentives present in the model are able to tell as about relevant aspects of the incentives involved in a state managed sickness insurance system. We calculate how the control variables depend on parameters such as the average productivity of the worker, the average productivity of the substitute, the wage of the substitute, and the search cost to find a substitute. Since we assume that the health status of the work force is heterogeneous and represented by a distribution function, we are also able to calculate the change in the work participation rate, as a function of the parameters.
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| 8. |
- Göransson, Jenny, et al.
(författare)
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Rapid Identification of Bio-Molecules Applied for Detection of Biosecurity Agents Using Rolling Circle Amplification
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:2, s. e31068-
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Tidskriftsartikel (refereegranskat)abstract
- Detection and identification of pathogens in environmental samples for biosecurity applications are challenging due to the strict requirements on specificity, sensitivity and time. We have developed a concept for quick, specific and sensitive pathogen identification in environmental samples. Target identification is realized by padlock- and proximity probing, and reacted probes are amplified by RCA (rolling-circle amplification). The individual RCA products are labeled by fluorescence and enumerated by an instrument, developed for sensitive and rapid digital analysis. The concept is demonstrated by identification of simili biowarfare agents for bacteria (Escherichia coli and Pantoea agglomerans) and spores (Bacillus atrophaeus) released in field.
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| 9. |
- Karlsson, Edvin, et al.
(författare)
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Clonality of erythromycin resistance in Francisella tularensis
- 2016
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 71:10, s. 2815-2823
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: We analysed diverse strains of Francisella tularensis subsp. holarctica to assess if its division into biovars I and II is associated with specific mutations previously linked to erythromycin resistance and to determine the distribution of this resistance trait across this subspecies. Methods:Three-hundred and fourteen F. tularensis subsp. holarctica strains were tested for erythromycin susceptibility and whole-genome sequences for these strains were examined for SNPs in genes previously associated with erythromycin resistance. Each strain was assigned to a global phylogenetic framework using genome-wide canonical SNPs. The contribution of a specific SNP to erythromycin resistance was examined using allelic exchange. The geographical distribution of erythromycin-resistant F. tularensis strains was further investigated by literature search. Results:There was a perfect correlation between biovar II strains (erythromycin resistance) and the phylogenetic group B.12. Only B.12 strains had an AaEuroS -> aEuroSC SNP at position 2059 in the three copies of the rrl gene. Introducing 2059C into an rrl gene of an erythromycin-susceptible F. tularensis strain resulted in resistance. An additional 1144 erythromycin-resistant strains were identified from the scientific literature, all of them from Eurasia. Conclusions:Erythromycin resistance in F. tularensis is caused by an A2059C rrl gene mutation, which exhibits a strictly clonal inheritance pattern found only in phylogenetic group B.12. This group is an extremely successful clone, representing the most common type of F. tularensis throughout Eurasia.
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| 10. |
- Larsson, Dhana E., et al.
(författare)
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The Cytotoxic Agents NSC-95397, Brefeldin A, Bortezomib and Sanguinarine Induce Apoptosis in Neuroendocrine Tumors In Vitro
- 2010
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 30:1, s. 149-156
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the apoptosis resulting from NSC 95397, brefeldin A, bortezomib and sanguinarine in neuroendocrine tumor cell lines. Materials and Methods: A multiparametric high-content screening assay for measurement of apoptosis was used. The human pancreatic carcinoid cell line, BON-1, human typical bronchial carcinoid cell line NCI-H727 and the human atypical bronchial carcinoid cell line NCI-H720 were tested. After incubation with cytotoxic drugs, the DNA-binding dye Hoechst 33342, fluorescein-tagged probes that covalently bind active caspase-3 and chloromethyl-X-rosamine to detect mitochondrial membrane potential were added. Image acquisition and quantitative measurement of fluorescence was performed using automated image capture and analysis instrument ArrayScan. In addition, nuclear morphology was examined on microscopic slides stained with May-Grunewald-Giemsa. Results: A time- and dose-dependent activation of caspase-3 and increase in nuclear fragmentation and condensation were observed for the drugs using a multiparametric apoptosis assay. These results were confirmed with nuclear morphological examination on microscopic slides. Conclusion: NSC 95397, brefeldin A, bortezomib and sanguinarine induced caspase-3 activation with modest changes in nuclear morphology.
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