| 42301. |
- Krasheninnikov, SI, et al.
(författare)
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Spinning of a charged dust particle in a magnetized plasma
- 2007
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Ingår i: Physics Letters A. - Amsterdam : Elsevier. - 0375-9601 .- 1873-2429. ; 361:1-2, s. 133-135
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel mechanism for spinning of a charged dust particle in a magnetized plasma. Specifically, we show that the dust particle spinning is caused by a torque that is produced due to interactions between the electric field E and an asymmetric dust particle electric dipole that is induced by the cross-field (viz. the E x B, where B is the external magnetic field) plasma flow. The torque acting on the dust particle is proportional to vertical bar E vertical bar(2), so that both laminar and turbulent electric fields can cause dust particle spinning. For plasma parameters typical of tokamak edges. the characteristic dust spinning frequency is of the order of several hundred kHz.
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| 42302. |
- Kraupner, Nadine, et al.
(författare)
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Evidence for selection of multi-resistant E. coli by hospital effluent.
- 2021
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 150, s. 106436-
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Tidskriftsartikel (refereegranskat)abstract
- There is a risk that residues of antibiotics and other antimicrobials in hospital and municipal wastewaters could select for resistant bacteria. Still, direct experimental evidence for selection is lacking. Here, we investigated if effluent from a large Swedish hospital, as well as influent and effluent from the connected municipal wastewater treatment plant (WWTP) select for antibiotic resistant Escherichia coli in three controlled experimental setups. Exposure of sterile-filtered hospital effluent to a planktonic mix of 149 different E. coli wastewater isolates showed a strong selection of multi-resistant strains. Accordingly, exposure to a complex wastewater community selected for strains resistant to several antibiotic classes. Exposing individual strains with variable resistance patterns revealed a rapid bactericidal effect of hospital effluent on susceptible, but not multi-resistant E. coli. No selection was observed after exposure to WWTP effluent, while exposure to WWTP influent indicated a small selective effect for ceftazidime and cefadroxil resistant strains, and only in the E. coli mix assay. An analysis of commonly used antibiotics and non-antibiotic pharmaceuticals in combination with growth and resistance pattern of individual E. coli isolates suggested a possible contribution of ciprofloxacin and β-lactams to the selection by hospital effluent. However, more research is needed to clarify the contribution from different selective agents. While this study does not indicate selection by the studied WWTP effluent, there is some indications of selective effects by municipal influent on β-lactam-resistant strains. Such effects may be more pronounced in countries with higher antibiotic use than Sweden. Despite the limited antibiotic use in Sweden, the hospital effluent strongly and consistently selected for multi-resistance, indicating widespread risks. Hence, there is an urgent need for further evaluation of risks for resistance selection in hospital sewers, as well as for strategies to remove selective agents and resistant bacteria.
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| 42303. |
- Kraupner, Nadine, et al.
(författare)
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Selective concentration for ciprofloxacin resistance in Escherichia coli grown in complex aquatic bacterial biofilms
- 2018
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 116, s. 255-268
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Tidskriftsartikel (refereegranskat)abstract
- There is concern that antibiotics in the environment can select for and enrich bacteria carrying acquired antibiotic resistance genes, thus increasing the potential of those genes to emerge in a clinical context. A critical question for understanding and managing such risks is what levels of antibiotics are needed to select for resistance in complex bacterial communities. Here, we address this question by examining the phenotypic and genotypic profiles of aquatic communities exposed to ciprofloxacin, also evaluating the within-species selection of resistant E. coli in complex communities. The taxonomic composition was significantly altered at ciprofloxacin exposure concentrations down to 1 μg/L. Shotgun metagenomic analysis indicated that mobile quinolone resistance determinants (qnrD, qnrS and qnrB) were enriched as a direct consequence of ciprofloxacin exposure from 1 μg/L or higher. Only at 5–10 μg/L resistant E.coli increased relative to their sensitive counterparts. These resistant E. coli predominantly harbored non-transferrable, chromosomal triple mutations (gyrA S83 L, D87N and parC S80I), which confer high-level resistance. In a controlled experimental setup such as this, we interpret effects on taxonomic composition and enrichment of mobile quinolone resistance genes as relevant indicators of risk. Hence, the lowest observed effect concentration for resistance selection in complex communities by ciprofloxacin was 1 μg/L and the corresponding no observed effect concentration 0.1 μg/L. These findings can be used to define and implement discharge or surface water limits to reduce risks for selection of antibiotic resistance in the environment. © 2018 Elsevier Ltd
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| 42304. |
- Kraupner, Nadine, et al.
(författare)
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Selective concentrations for trimethoprim resistance in aquatic environments
- 2020
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- Antibiotic resistance presents a serious and still growing threat to human health. Environmental exposure levels required to select for resistance are unknown for most antibiotics. Here, we evaluated different experimental approaches and ways to interpret effect measures, in order to identify what concentration of trimethoprim that are likely to select for resistance in aquatic environments. When grown in complex biofilms, selection for resistant E. coli increased at 100 mu g/L, whereas there was only a non-significant trend with regards to changes in taxonomic composition within the tested range (0-100 mu g/L). Planktonic co-culturing of 149 different E. coli strains isolated from sewage again confirmed selection at 100 mu g/L. Finally, pairwise competition experiments were performed with engineered E. coli strains carrying different trimethoprim resistance genes (dfr) and their sensitive counterparts. While strains with introduced resistance genes grew slower than the sensitive ones at 0 and 10 mu g/L, a significant reduction in cost was found already at 10 mu g/L. Defining lowest effect concentrations by comparing proportion of resistant strains to sensitive ones at the same time point, rather than to their initial ratios, will reflect the advantage a resistance factor can bring, while ignoring exposure-independent fitness costs. As costs are likely to be highly dependent on the specific environmental and genetic contexts, the former approach might be more suitable as a basis for defining exposure limits with the intention to prevent selection for resistance. Based on the present and other studies, we propose that 1 mu g/L would be a reasonably protective exposure limit for trimethoprim in aquatic environments.
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| 42305. |
- Krauskopf, Julian, et al.
(författare)
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Blood Transcriptome Response to Environmental Metal Exposure Reveals Potential Biological Processes Related to Alzheimer's Disease
- 2020
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Ingår i: Frontiers in Public Health. - : Frontiers Media S.A.. - 2296-2565. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is a neurodegenerative disease which is manifested by a progressive and irreversible decline of cognition, memory loss, a shortened attention span, and changes in personality. Aging and genetic pre-dispositions, particularly the presence of a specific form of apolipoprotein E (APOE), are main risk factors of sporadic AD; however, a large body of evidence has shown that multiple environmental factors, including exposure to toxic metals, increase the risk for late onset AD. Lead (Pb) and cadmium (Cd) are ubiquitous toxic metals with a wide range of applications resulting in global distribution in the environment and exposure of all living organisms on earth. In addition to being classified as carcinogenic (Cd) and possibly carcinogenic (Pb) to humans by the International Agency for Research on Cancer, both compounds disrupt metal homeostasis and can cause toxic responses at the cellular and organismal levels. Pb toxicity targets the central nervous system and evidence for that has emerged also for Cd. Recent epidemiological studies show that both metals possibly are etiological factors of multiple neurodegenerative diseases, including Alzheimer's disease (AD). To further explore the association between metal exposure and AD risk we applied whole transcriptome gene expression analysis in peripheral blood leukocytes (PBLs) from 632 subjects of the general population, taken from the EnviroGenomarkers project. We used linear mixed effect models to associate metal exposure to gene expression after adjustment for gender, age, BMI, smoking, and alcohol consumption. For Pb exposure only few associations were identified, including a downregulation of the human eukaryotic translation initiation factor 5 (eIF5). In contrast, Cd exposure, particularly in males, revealed a much stronger transcriptomic response, featuring multiple pathways related to pathomolecular mechanisms of AD, such as endocytosis, neutrophil degranulation, and Interleukin-7 signaling. A gender stratified analysis revealed that the Cd responses were male-specific and included a downregulation of the APOE gene in men. This exploratory study revealed novel hypothetical findings which might contribute to the understanding of the neurotoxic effects of chronic Pb and Cd exposure and possibly improve our knowledge on the molecular mechanisms linking metal exposure to AD risk.
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| 42306. |
- Krauskopf, Julian, et al.
(författare)
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MicroRNA profile for health risk assessment : environmental exposure to persistent organic pollutants strongly affects the human blood microRNA machinery
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Persistent organic pollutants (POPs) are synthetic chemical substances that accumulate in our environment. POPs such as polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane (DDT) have been classified as carcinogenic to humans and animals. Due to their resistance to biodegradation humans are still exposed to these compounds worldwide. We aim to evaluate the miRNA and transcriptomic response of a human population exposed to POPs. The miRNA and transcriptomic response was measured in blood of healthy subjects by microarray technology and associated with the serum concentrations of six PCB congeners, DDE (a common DDT metabolite), and HCB. A total of 93 miRNA levels appeared significantly associated with the POP-exposure (FDR < 0.05). The miRNA profile includes four tumor suppressor miRNAs, namely miR-193a-3p, miR-152, miR-31-5p and miR-34a-5p. Integration of the miRNA profile with the transcriptome profile suggests an interaction with oncogenes such as MYC, CCND1, BCL2 and VEGFA. We have shown that exposure to POPs is associated with human miRNA and transcriptomic responses. The identified miRNAs and target genes are related to various types of cancer and involved in relevant signaling pathways like wnt and p53. Therefore, these miRNAs may have great potential to contribute to biomarker-based environmental health risk assessment.
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| 42307. |
- Krauss, Joachim K., et al.
(författare)
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Technology of deep brain stimulation : current status and future directions
- 2021
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Ingår i: Nature Reviews Neurology. - : Springer Nature. - 1759-4758 .- 1759-4766. ; 17:2, s. 75-87
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Forskningsöversikt (refereegranskat)abstract
- Deep brain stimulation (DBS) is a neurosurgical procedure that allows targeted circuit-based neuromodulation. DBS is a standard of care in Parkinson disease, essential tremor and dystonia, and is also under active investigation for other conditions linked to pathological circuitry, including major depressive disorder and Alzheimer disease. Modern DBS systems, borrowed from the cardiac field, consist of an intracranial electrode, an extension wire and a pulse generator, and have evolved slowly over the past two decades. Advances in engineering and imaging along with an improved understanding of brain disorders are poised to reshape how DBS is viewed and delivered to patients. Breakthroughs in electrode and battery designs, stimulation paradigms, closed-loop and on-demand stimulation, and sensing technologies are expected to enhance the efficacy and tolerability of DBS. In this Review, we provide a comprehensive overview of the technical development of DBS, from its origins to its future. Understanding the evolution of DBS technology helps put the currently available systems in perspective and allows us to predict the next major technological advances and hurdles in the field.
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| 42308. |
- Kravchuk, O. I., et al.
(författare)
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A simple and efficient method of inducing targeted deletions in the drosophila genome
- 2015
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Ingår i: Russian journal of genetics. - 1022-7954 .- 1608-3369. ; 51:11, s. 1144-1148
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Tidskriftsartikel (refereegranskat)abstract
- Deletion mutagenesis is one of the most efficient approaches to studying gene function. However, conventional methods of inducing targeted mutations in the drosophila genome are timeand labor-consuming. This work proposes a new, simple, and effective method of producing drosophila mutants with gene deletions. The method involves the insertion of I-SceI and I-CreI recognition sites and a fragment homologous to the target sequence into the chromosome region of interest by means of an attB-containing construct, the induction of double-strand DNA breaks by the appropriate meganuclease, and their repair by homologous recombination. The procedure results in a deletion extending from the attP-site to the target locus. A cassette was designed to enable single-step construct production for the deletion of any given genomic region. A set of markers facilitates the selection of recombination events. The efficacy of the proposed technique was confirmed by the induction of a 47-kb deletion containing the qtc gene.
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| 42309. |
- Kravchuk, Oksana, et al.
(författare)
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Transvection in Drosophila : trans-interaction between yellow enhancers and promoter is strongly suppressed by a cis-promoter only in certain genomic regions
- 2017
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Ingår i: Chromosoma. - : Springer Science and Business Media LLC. - 0009-5915 .- 1432-0886. ; 126:3, s. 431-441
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Tidskriftsartikel (refereegranskat)abstract
- Transvection is a phenomenon of interallelic communication whereby enhancers of one allele can activate a promoter located on the homologous chromosome. It has been shown for many independent genes that enhancers preferentially act on the cis-linked promoter, but deletion of this promoter allows the enhancers to act in trans. Here, we tested whether this cis-preference in the enhancer-promoter interaction could be reconstituted outside of the natural position of a gene. The yellow gene was chosen as a model system. Transgenic flies were generated that carried the yellow gene modified by the inclusion of the strategically placed recognition sites for the Cre and Flp recombinases. To facilitate transvection, an endogenous Su(Hw) insulator (1A2) or gypsy insulator was placed behind the yellow gene. Independent action of the recombinases produced a pair of derivative alleles, one containing the promoter-driven yellow gene, and the other, the enhancers and promoter that failed to produce a functional yellow protein. As a result, we observed strong transvection in many genomic regions, suggesting that a complete cis-preference of the enhancer-promoter interactions is mainly restricted to genes in their natural loci.
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| 42310. |
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