| 1. |
- Nilsson, E.J.C., et al.
(författare)
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Using microdispensing to manufacture a customized cell dish for microbeam irradiation of single, living cells
- 2009
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 267:7, s. 1199-1205
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Tidskriftsartikel (refereegranskat)abstract
- In this paper is described the preparation of patterned cell dishes to be used in studies of low dose irradiation effects on living cells. Using a droplet microdispenser, an 8 mu m thick polypropylene cell substrate, to which cells do not naturally adhere, was coated in a matrix pattern with the cell adhesive mussel protein Cell-Tak. Cells were shown to adhere and grow on the protein-coated spots, but not on the uncoated parts, providing for guided cell growth. Cultivation of isolated cell colonies provides an opportunity to study how low doses of ionizing radiation affect neighbouring un-irradiated cell colonies. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Nilsson, E J Charlotta, et al.
(författare)
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Evaluation of cryoanalysis as a tool for analyzing elemental distributionin ‘‘live’’ tardigrades using micro-PIXE
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 332, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- Although heavy on labor and equipment, thus not often applied, cryoanalysis of frozen hydrated biological specimens can provide information that better reflects the living state of the organism, compared with analysis in the freeze-dried state. In this paper we report a study where the cryoanalysis facility with cryosectioning capabilities at Materials Research Department, iThemba LABS, South Africa was employed to evaluate the usefulness of combining three ion beam analytical methods (μPIXE, RBS and STIM) to analyze a biological target where a better elemental compositional description is needed – the tardigrade. Imaging as well as quantification results are of interest.In a previous study, the element composition and redistribution of elements in the desiccated and active states of two tardigrade species was investigated. This study included analysis of both whole and sectioned tardigrades, and the aim was to analyze each specimen twice; first frozen hydrated and later freeze-dried. The combination of the three analytical techniques proved useful: elements from C to Rb in the tardigrades could be determined and certain differences in distribution of elements between the frozen hydrated and the freeze-dried states were observed. RBS on frozen hydrated specimens provided knowledge of matrix elements.
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| 3. |
- Orho-Melander, Marju, et al.
(författare)
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Common Missense Variant in the Glucokinase Regulatory Protein Gene Is Associated With Increased Plasma Triglyceride and C-Reactive Protein but Lower Fasting Glucose Concentrations
- 2008
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 57:11, s. 3112-3121
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-Using the genome-wide association approach, we recently identified the glucokinase regulatory protein gene (GCKR, rs780094) region as a novel quantitative trait locus for plasma triglyceride concentration in Europeans. Here, we sought to study the association of GCKR variants with metabolic phenotypes, including measures of glucose homeostasis, to evaluate the GCYR locus in samples of non-European ancestry and to fine-map across the associated genomic interval. RESEARCH DESIGN AND METHODS-We performed association studies in 12 independent cohorts comprising >45,000 individuals representing several ancestral groups (whites from Northern and Southern Europe, whites from the U.S., African Americans from the U.S., Hispanics of Caribbean origin, and Chinese, Malays, and Asian Indians from Singapore). We conducted genetic fine-mapping across the similar to 417-kb region of linkage disequilibrium. spanning GCKR and 16 other genes on chromosome 2p23 by imputing untyped HapMap single nucleotide polymorphisms (SNPs) and genotyping 104 SNPs across the associated genomic interval. RESULTS-We provide comprehensive evidence that GCYR rs780094 is associated with opposite effects on fasting plasma triglyceride (P-meta = 3 x 10(-56)) and glucose (P-meta = 1 x 10(-13)) concentrations. In addition, we confirmed recent reports that the same SNP is associated with C-reactive protein (CRP) level (P = 5 x 10(-5)). Both fine-mapping approaches revealed a common missense GCKR variant (rs1260326, Pro446Leu, 34% frequency, r(2) = 0.93 with rs780094) as the strongest association signal in the region. CONCLUSIONS-These findings point to a molecular mechanism in humans by which higher triglycerides and CRP can be coupled with lower plasma glucose concentrations and position GCKR in central pathways regulating both hepatic triglyceride and glucose metabolism. Diabetes 57:3112-3121, 2008
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| 4. |
- Bosi, Ferdinando, et al.
(författare)
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Late magmatic controls on the origin of schorlitic and foititic tourmalines from late-Variscan peraluminous granites of the Arbus pluton (SW Sardinia, Italy) : Crystal-chemical study and petrological constraints
- 2018
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Ingår i: Lithos. - : Elsevier BV. - 0024-4937 .- 1872-6143. ; 308-309, s. 395-411
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Tidskriftsartikel (refereegranskat)abstract
- Tourmalines from the late-Variscan Arbus pluton (SW Sardinia) and its metamorphic aureole were structurally and chemically characterized by single-crystal X-ray diffraction, electron and nuclear microprobe analysis, Mössbauer, infrared and optical absorption spectroscopy, to elucidate their origin and relationships with the magmatic evolution during the pluton cooling stages. The Arbus pluton represents a peculiar shallow magmatic system, characterized by sekaninaite (Fe-cordierite)-bearing peraluminous granitoids, linked via AFC processes to gabbroic mantle-derived magmas. The Fe2+-Al-dominant tourmalines occur in: a) pegmatitic layers and pods, as prismatic crystals; b) greisenized rocks and spotted granophyric dikes, as clots or nests of fine-grained crystals in small miaroles locally forming orbicules; c) pegmatitic veins and pods close to the contacts within the metamorphic aureole. Structural formulae indicate that tourmaline in pegmatitic layers is schorl, whereas in greisenized rocks it ranges from schorl to fluor-schorl. Tourmalines in thermometamorphosed contact aureole are schorl, foitite and Mg-rich oxy-schorl. The main substitution is Na + Fe2+ ↔ □ + Al, which relates schorl to foitite. The homovalent substitution (OH) ↔ F at the O1 crystallographic site relates schorl to fluor-schorl, while the heterovalent substitution Fe2+ + (OH, F) ↔ Al + O relates schorl/fluor-schorl to oxy-schorl. Tourmaline crystallization in the Arbus pluton was promoted by volatile (B, F and H2O) enrichment, low oxygen fugacity and Fe2+ activity. The mineralogical evolutive trend is driven by decreasing temperature, as follows: sekaninaite + quartz → schorl + quartz → fluor-schorl + quartz → foitite + quartz. The schorl → foitite evolution represents a distinct trend towards (Al + □) increase and unit-cell volume decrease. These trends are typical of granitic magmas and consistent with Li-poor granitic melts, as supported by the absence of elbaite and other Li-minerals in the Arbus pluton. Tourmaline-bearing rocks reflect the petrogenetic significance of contribution from a metapelitic crustal component during the evolution of magmas in the middle-upper crust.
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| 5. |
- de la Rosa, Nathaly, et al.
(författare)
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Quantification of lithium at ppm level in geological samples using nuclear reaction analysis
- 2018
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 317:1, s. 253-259
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Tidskriftsartikel (refereegranskat)abstract
- Proton-induced reaction (p,α) is one type of nuclear reaction analysis (NRA) suitable especially for light element quantification. In the case of lithium quantification presented in this work, accelerated protons with an energy about of 850 keV were used to induce the 7Li(p,α)4He reaction in standard reference and geological samples such as tourmaline and other Li-minerals. It is shown that this technique for lithium quantification allowed for measurement of concentrations down below one ppm. The possibility to relate the lithium content with the boron content in a single analysis was also demonstrated using tourmaline samples, both in absolute concentration and in lateral distribution. In addition, Particle induced X-ray emission (PIXE) was utilized as a complementary IBA technique for simultaneous mapping of elements heavier than sodium.
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| 6. |
- Lagerqvist, Nina, et al.
(författare)
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Evaluation of 11 SARS-CoV-2 antibody tests by using samples from patients with defined IgG antibody titers
- 2021
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the performance of 11 SARS-CoV-2 antibody tests using a reference set of heat-inactivated samples from 278 unexposed persons and 258 COVID-19 patients, some of whom contributed serial samples. The reference set included samples with a variation in SARS-CoV-2 IgG antibody titers, as determined by an in-house immunofluorescence assay (IFA). The five evaluated rapid diagnostic tests had a specificity of 99.0% and a sensitivity that ranged from 56.3 to 81.6% and decreased with low IFA IgG titers. The specificity was > 99% for five out of six platform-based tests, and when assessed using samples collected ≥ 22 days after symptom onset, two assays had a sensitivity of > 96%. These two assays also detected samples with low IFA titers more frequently than the other assays. In conclusion, the evaluated antibody tests showed a heterogeneity in their performances and only a few tests performed well with samples having low IFA IgG titers, an important aspect for diagnostics and epidemiological investigations.
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| 7. |
- Nilsson, E. J. Charlotta, et al.
(författare)
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Tolerance to proton irradiation in the eutardigrade Richtersius coronifer : a nuclear microprobe study
- 2010
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Ingår i: International Journal of Radiation Biology. - 0955-3002 .- 1362-3095. ; 86:5, s. 420-427
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Tidskriftsartikel (refereegranskat)abstract
- Purpose:The tardigrade Richtersius coronifer has previously been shown to tolerate very high doses of low linear energy transfer (low-LET) radiation (gamma rays). The purpose of this study was to extend our knowledge on radiation tolerance in this species by investigating the dose-response to high-LET radiation in terms of protons.Materials and methods:Dehydrated tardigrades of the species R. coronifer were irradiated with 2.55 MeV (megaelectronvolts) protons at doses ranging from 500 gray (Gy) to 15,000 Gy, to investigate the dose-viability relationship. In addition, a focused proton microbeam was utilised to determine the areal mass distribution, using the ion beam analytical technique STIM (Scanning Transmission Ion Microscopy).Results:The experiment suggests that R. coronifer is unaffected by doses of proton irradiation up to 10,000 Gy, but shows very little viability at higher doses. The STIM analysis revealed that the thickness of the dehydrated tardigrades exceeds 150 μm, and that a fraction of the protons may not be fully absorbed.Conclusion:Our results are in line with previous studies of exposure to high-LET radiation in tardigrades, indicating that these animals are equally or even more tolerant to high-LET compared to low-LET gamma radiation. The physiological background to this remarkable result is currently unknown, but deserves investigation.
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| 8. |
- Pallon, Jan, et al.
(författare)
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A new quantitative X-ray system for micro-PIXE analysis
- 2017
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Ingår i: X-Ray Spectrometry. - : Wiley. - 0049-8246. ; 46:5, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- Particle Induced X-ray Emission is a well-established technique for quantitative elemental analysis down to trace levels. During microbeam analysis, where the beam is collimated and focused into a small spot, the beam current reduces to nA or less. The generation of characteristic X-rays is reduced in the same proportion, leading to long data-acquisition times. This can partly be compensated for by using detectors with a large solid angle. In this work, the performance of an annular eight-element silicon drift detector with a total solid angle of 261 msr is described. The initial calibration of the detector was performed using thin elemental standards. Charge measurement was carried out both in a Faraday Cup positioned after the sample and by a pre-sample electrostatic deflection system sampling the beam charge into another Faraday Cup. The two methods were used in parallel and compared during the calibration measurements. A recently installed Versa Module Europe (VME) based data acquisition system equipped with, for example, multi-hit time-to-digital converters, amplifiers, and 32-channel scalers, was used to record data in event-by-event mode for simultaneous data evaluation on multiple computers. Off-line dead time and pile-up corrections were made on the event data that was sorted into spectra and fitted with the GeoPIXE software. The pre-sample deflection charge measurement gave consistent values for the calibration, and this is an important observation implying that non-conductive and thick samples will be able to quantify without the use of internal standards.
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