| 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. |
- Borysiuk, Maciek, et al.
(författare)
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Evaluation of a setup for pNRA at LIBAF for applications in geosciences
- 2014
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 332, s. 202-206
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Tidskriftsartikel (refereegranskat)abstract
- A new setup for photon tagged nuclear reaction analysis pNRA is being developed at Lund's ion beam analysis facility LIBAF. Particle induced gamma ray emission PIGE and nuclear reaction analysis NRA are two methods that have been extensively used for light isotope measurement in ion beam analysis IBA. There is an abundance of nuclear reactions between light elements and MeV protons, deuterons and alpha particles. This means that in principle all elements from lithium all the way up to chlorine can be analyzed using those techniques. Detection limits can be improved for some elements, if those two methods are fused together into pNRA. The new setup for pNRA will benefit from advances in detector technology that occurred during the last 20 years. A LaBr3 scintillator detector and an annular double sided silicon strip detector DSSSD are used in coincidence to detect a gamma and a charged particle respectively. Both detectors are connected to a VME based data acquisition system. Of primary interest in this work is the analysis of isotopic ratios of light elements in geological samples, which are usually thick with a complex matrix. This setup can be for instance used to measure isotopic fractionation of oxygen and boron. We will present the setup and discuss its capabilities. (C) 2014 The Authors. Published by Elsevier B.V.
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| 3. |
- Culverhouse, R. C., et al.
(författare)
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Collaborative meta-analysis finds no evidence of a strong interaction between stress and 5-HTTLPR genotype contributing to the development of depression
- 2018
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 23:1, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- The hypothesis that the S allele of the 5-HTTLPR serotonin transporter promoter region is associated with increased risk of depression, but only in individuals exposed to stressful situations, has generated much interest, research and controversy since first proposed in 2003. Multiple meta-analyses combining results from heterogeneous analyses have not settled the issue. To determine the magnitude of the interaction and the conditions under which it might be observed, we performed new analyses on 31 data sets containing 38 802 European ancestry subjects genotyped for 5-HTTLPR and assessed for depression and childhood maltreatment or other stressful life events, and meta-analysed the results. Analyses targeted two stressors (narrow, broad) and two depression outcomes (current, lifetime). All groups that published on this topic prior to the initiation of our study and met the assessment and sample size criteria were invited to participate. Additional groups, identified by consortium members or self-identified in response to our protocol (published prior to the start of analysis) with qualifying unpublished data, were also invited to participate. A uniform data analysis script implementing the protocol was executed by each of the consortium members. Our findings do not support the interaction hypothesis. We found no subgroups or variable definitions for which an interaction between stress and 5-HTTLPR genotype was statistically significant. In contrast, our findings for the main effects of life stressors (strong risk factor) and 5-HTTLPR genotype (no impact on risk) are strikingly consistent across our contributing studies, the original study reporting the interaction and subsequent meta-analyses. Our conclusion is that if an interaction exists in which the S allele of 5-HTTLPR increases risk of depression only in stressed individuals, then it is not broadly generalisable, but must be of modest effect size and only observable in limited situations.
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| 4. |
- Frost, R. J.W., et al.
(författare)
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One detector, all the light elements – Low-background NRA, RBS and ERDA for the quantification of elements from hydrogen to fluorine
- 2021
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 494-495, s. 34-45
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Tidskriftsartikel (refereegranskat)abstract
- Presented is a review of the accomplishments, of the light-element program, conducted at the Lund Ion-Beam Analysis Facility. A detailed account is given of the current experimental setup at the total Ion-Beam Analysis Chamber, which is equipped with two Double-Sided Silicon Strip Detectors for charge particle detection, a silicon drift detector for PIXE analysis, an electrostatic deflection system for charge measurement and implements a Nuclear Micro-Probe. A summary of the work conducted to date on the quantification of low Z elements is presented on a case by case basis. Details of the current work efforts and an overview of the advances which are intended in the near future are given.
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| 5. |
- Kristiansson, Per, et al.
(författare)
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The implementation of a DSSSD in the upgraded boron analysis at LIBAF for applications in geochemistry
- 2014
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 332, s. 207-211
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Tidskriftsartikel (refereegranskat)abstract
- Interest in high spatial resolution boron analyses from a geochemical perspective is related to the recognition of boron as an important tracer of chemical recycling in the Earth, due to the high solubility of boron in aqueous fluids and silicate melts. Although boron is not a nominal component in common silicates they may still contain significant B-concentrations and hence constitute important boron reservoirs in the deeper parts of the Earth. Boron analyses have been performed at the Lund Ion Beam Analytical Facility for almost 20 years. For the analysis the nuclear reaction p+B-11 is used with beam energy just below 700 keV where the reaction has a broad resonance. In this paper we describe an upgrade of the system with a double sided silicon strip detector, which allows for much higher count rates compared to the old annular surface detector based system. A gain close to 20 in the data rate allows for high resolution mapping of boron distributions in crystals. This is illustrated by a number of examples. In addition, the detection limits for boron in geological samples are improved, now around 5 ppmw. In this work we address issues with data quality, especially charge normalization, lifetime correction and subtraction of different background components. (C) 2014 The Authors. Published by Elsevier B.V.
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| 6. |
- Nilsson, E. J. C., et al.
(författare)
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Evaluation of cryoanalysis as a tool for analyzing elemental distribution in live tardigrades using micro-PIXE
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 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 (mu PIXE, 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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| 7. |
- Ros, Linus, et al.
(författare)
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Calibration of an elastic recoil setup for D/H-ratios close to natural abundance
- 2014
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 332, s. 187-190
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Tidskriftsartikel (refereegranskat)abstract
- Nominally Anhydrous Minerals (NAM) in the Earth's mantle contain trace amounts of hydrogen, as a result of the NAM's ability to incorporate hydroxyl ions. The isotopic composition of these hydrogen reservoirs is for the Earth's crust, well characterized. The knowledge of the isotopic composition of the Earth's interior on the other hand is limited. It is believed that the hydrogen composition in the interior is isotopically heterogeneous and that there may exist several reservoirs of hydrogen, characterized by different deuterium/hydrogen-ratios. Characterization of these hydrogen reservoirs can provide valuable information about the mass transport of hydrogen during the evolution of the planet. In this work we present a variant of the proton-proton scattering technique with which we are capable of performing simultaneous measurements of deuterium and hydrogen. The method has been tested with a 2.9 MeV deuteron beam on a polyethylene standard, with D/H ratio close to the natural abundance, and on a thin sample of Muscovite with a hydrogen concentration of 4800 wt-ppm. This is followed by a discussion about limitations and capabilities of the technique. (C) 2014 The Authors. Published by Elsevier B.V.
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| 8. |
- Rutardottir, Sigurbjörg, et al.
(författare)
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The cysteine 34 residue of A1M/α1-microglobulin is essential for protection of irradiated cell cultures and reduction of carbonyl groups.
- 2013
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Ingår i: Free Radical Research. - : Informa UK Limited. - 1029-2470 .- 1071-5762. ; 47:6-7, s. 541-550
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Tidskriftsartikel (refereegranskat)abstract
- α1-microglobulin (A1M) is a 26 kDa plasma and a tissue protein belonging to the lipocalin family. The reductase and free radical scavenger A1M has been shown to protect cells and extracellular matrix against oxidative and irradiation-induced damage. The reductase activity was previously shown to depend upon an unpaired cysteinyl side-chain, C34, and three lysyl side-chains, K92, 118, and 130, located around the open end of the lipocalin pocket. The aim of this work was to investigate whether the cell and matrix protection by A1M is a result of its reductase activity by using A1M-variants with site-directed mutations of the C34, K92, K118, and K130 positions. The results show that the C34 side-chain is an absolute requirement for protection of HepG2 cell cultures against alpha-particle irradiation-induced cell death, upregulation of stress response and cell cycle regulation genes. Mutation of C34 also resulted in loss of the reduction capacity toward heme- and hydrogen peroxide-oxidized collagen, and the radical species 2,2´-azino-bis (3-ethyl-benzo-thiazoline-6-sulphonic acid) (ABTS). Furthermore, mutation of C34 significantly suppressed the cell-uptake of A1M. The K92, K118, and K130 side-chains were of minor importance in cell protection and reduction of oxidized collagen but strongly influenced the reduction of the ABTS-radical. It is concluded that antioxidative protection of cells and collagen by A1M is totally dependent on its C34 amino acid residue. A model of the cell protection mechanism of A1M should be based on the redox activity of the free thiolyl group of the C34 side-chain and a regulatory role of the K92, K118, and K130 residues.
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