| 1. |
- Bäckström, Gloria, et al.
(författare)
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Track structure of protons and other light ions in liquid water : Applications of the LIonTrack code at the nanometer scale
- 2013
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Ingår i: Medical physics (Lancaster). - : Wiley. - 0094-2405. ; 40:6, s. 064101-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The LIonTrack (Light Ion Track) Monte Carlo (MC) code for the simulation of H+, He2+, and other light ions in liquid water is presented together with the results of a novel investigation of energy-deposition site properties from single ion tracks. Methods: The continuum distorted-wave formalism with the eikonal initial state approximation (CDW-EIS) is employed to generate the initial energy and angle of the electrons emitted in ionizing collisions of the ions with H2O molecules. The model of Dingfelder et al. ["Electron inelastic-scattering cross sections in liquid water," Radiat. Phys. Chem. 53, 1-18 (1998); " Comparisons of calculations with PARTRAC and NOREC: Transport of electrons in liquid water," Radiat. Res. 169, 584-594 (2008)] is linked to the general-purpose MC code PENELOPE/penEasy to simulate the inelastic interactions of the secondary electrons in liquid water. In this way, the extended PENELOPE/penEasy code may provide an improved description of the 3D distribution of energy deposits (EDs), making it suitable for applications at the micrometer and nanometer scales. Results: Single-ionization cross sections calculated with the ab initio CDW-EIS formalism are compared to available experimental values, some of them reported very recently, and the theoretical electronic stopping powers are benchmarked against those recommended by the ICRU. The authors also analyze distinct aspects of the spatial patterns of EDs, such as the frequency of nearest-neighbor distances for various radiation qualities, and the variation of the mean specific energy imparted in nanoscopic targets located around the track. For 1 MeV/u particles, the C6+ ions generate about 15 times more clusters of six EDs within an ED distance of 3 nm than H+. Conclusions: On average clusters of two to three EDs for 1 MeV/u H+ and clusters of four to five EDs for 1 MeV/u C6+ could be expected for a modeling double strand break distance of 3.4 nm.
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| 2. |
- Ismail, K. M. K., et al.
(författare)
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Clinical subtypes of core premenstrual disorders: a Delphi survey
- 2013
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Ingår i: Archives of Womens Mental Health. - : Springer Science and Business Media LLC. - 1434-1816 .- 1435-1102. ; 16:3, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to classify the clinical subtypes of core premenstrual disorders during
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| 3. |
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| 4. |
- Bäckström, Gloria, 1979-
(författare)
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Protons, other Light Ions, and 60Co Photons : Study of Energy Deposit Clustering via Track Structure Simulations
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radiotherapy aims to sterilize cancer cells through ionization induced damages to their DNA whilst trying to reduce dose burdens to healthy tissues. This can be achieved to a certain extent by optimizing the choice of radiation to treat the patient, i.e. the types of particles and their energy based on their specific interaction patterns. In particular, the formation of complex clusters of energy deposits (EDs) increases with the linear energy transferred for a given particle. These differences cause variation in the relative biological effectiveness (RBE). The complexity of ED clusters might be related to complex forms of DNA damage, which are more difficult to repair and therefore prone to inactivate the cells. Hence, mapping of the number and complexity of ED clusters for different radiation qualities could aid to infer a surrogate measure substituting physical dose and LET as main predictors for the RBE . In this work the spatial patterns of EDs at the nanometre scale were characterized for various energies of proton, helium, lithium and carbon ions. A track structure Monte Carlo code, LIonTrack, was developed to accurately simulate the light ion tracks in liquid water. The methods to emulate EDs at clinical dose levels in cell nucleus-sized targets for both 60Co photons and light ions were established, and applied to liquid water targets. All EDs enclosed in such targets were analyzed with a specifically developed cluster algorithm where clustering was defined by a single parameter, the maximum distance between nearest neighbour EDs. When comparing measured RBE for different radiation qualities, there are cases for which RBE do not increase with LET but instead increase with the frequencies of high order ED clusters.A test surrogate-measure based on ED cluster frequencies correlated to parameters of experimentally determined cell survival. The tools developed in this thesis can facilitate future exploration of semi-mechanistic modelling of the RBE.
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| 5. |
- Bäckström, Torbjörn, et al.
(författare)
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Paradoxical effects of GABA-A modulators may explain sex steroid induced negative mood symptoms in some persons
- 2011
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Ingår i: Neuroscience. - Oxford : Elsevier BV. - 0306-4522 .- 1873-7544. ; 191:Special issue, s. 46-54
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Forskningsöversikt (refereegranskat)abstract
- Some women have negative mood symptoms, caused by progestagens in hormonal contraceptives or sequential hormone therapy or by progesterone in the luteal phase of the menstrual cycle, which may be attributed to metabolites acting on the GABA-A receptor. The GABA system is the major inhibitory system in the adult CNS and most positive modulators of the GABA-A receptor (benzodiazepines, barbiturates, alcohol, GABA steroids), induce inhibitory (e.g. anesthetic, sedative, anticonvulsant, anxiolytic) effects. However, some individuals have adverse effects (seizures, increased pain, anxiety, irritability, aggression) upon exposure. Positive GABA-A receptor modulators induce strong paradoxical effects including negative mood in 3%-8% of those exposed, while up to 25% have moderate symptoms. The effect is biphasic: low concentrations induce an adverse anxiogenic effect while higher concentrations decrease this effect and show inhibitory, calming properties. The prevalence of premenstrual dysphoric disorder (PMDD) is also 3%-8% among women in fertile ages, and up to 25% have more moderate symptoms of premenstrual syndrome (PMS). Patients with PMDD have severe luteal phase-related symptoms and show changes in GABA-A receptor sensitivity and GABA concentrations. Findings suggest that negative mood symptoms in women with PMDD are caused by the paradoxical effect of allopregnanolone mediated via the GABA-A receptor, which may be explained by one or more of three hypotheses regarding the paradoxical effect of GABA steroids on behavior: (1) under certain conditions, such as puberty, the relative fraction of certain GABA-A receptor subtypes may be altered, and at those subtypes the GABA steroids may act as negative modulators in contrast to their usual role as positive modulators; (2) in certain brain areas of vulnerable women the transmembrane C1(-) gradient may be altered by factors such as estrogens that favor excitability; (3) inhibition of inhibitory neurons may promote disinhibition, and hence excitability. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain. (C) 2011 Published by Elsevier Ltd on behalf of IBRO.
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| 6. |
- Del Campo, Judith, et al.
(författare)
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Intranasal immunization with a proteoliposome-derived cochleate containing recombinant gD protein confers protective immunity against genital herpes in mice.
- 2010
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Ingår i: Vaccine. - : Elsevier BV. - 1873-2518 .- 0264-410X. ; 28:5, s. 1193-200
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the potential of intranasal (IN) immunization with Neisseria meningitides B proteoliposome (AFPL1) and AFPL1-derived cochleate (AFCo1), containing glycoprotein D (gD) of herpes simplex virus type 2 (HSV-2) for induction of protective immunity against genital herpes infection in mice. We could show that IN immunization with both AFPL1 and AFCo1 containing gD induced gD-specific IgG antibody and lymphoproliferative responses. However, IFN-gamma response could only be detected in CD4(+) splenic cells and genital lymph node cells of the AFCo1gD immunized mice upon recall antigen stimulation in vitro. Importantly, IN immunization with AFCo1gD could elicit a complete protection against an otherwise lethal vaginal challenge with HSV-2, while the AFPL1gD immunized mice were only partially protected. Further, we could show that the IFN-gamma response and protective immunity observed after IN immunization with AFCo1gD are mediated via the adaptor molecule myeloid differentiation factor 88. These data may have implications for the development of a mucosal vaccine against genital herpes.
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| 7. |
- Eklund, Mona, et al.
(författare)
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Psychometric properties and factor structure of the 13-item satisfaction with daily occupations scale when used with people with mental health problems
- 2014
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Ingår i: Health and Quality of Life Outcomes. - : Springer Science and Business Media LLC. - 1477-7525. ; 12:191
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Tidskriftsartikel (refereegranskat)abstract
- Background: In mental health care practice and research it is increasingly recognized that clients' subjective perceptions of everyday occupations, such as satisfaction, are important in recovery from mental illness. Instruments thus need to be developed to assess satisfaction with everyday occupations. The aim of the present study was to assess psychometric properties of the 13-item Satisfaction with Daily Occupation (SDO-13) when used with people with mental health problems, including its internal consistency, factor structure, construct validity and whether the scale produced ceiling or floor effects. An additional question concerned if the factor structure varied whether the participants were, or were not, presently engaged in the activity they rated. Methods: The interview-based SDO-13 includes items pertaining to work/studies, leisure, home maintenance, and self-care occupations. Whether the person currently performs an occupation or not, he/she is asked to indicate his/her satisfaction with that occupation. The SDO-13 was completed with 184 persons with mental illness. Residual variables were created to remove the variation linked with currently performing the targeted occupation or not and to assess the factor structure of the SDO-13. The indicators of general satisfaction with daily occupations, self-esteem and global functioning were used to assess construct validity. The statistical methods included tests of homogeneity, confirmatory factor analysis and Pearson correlations. Results: The internal consistency was satisfactory at 0.79. A three-factor solution indicated that the construct behind the SDO-13 was composed of three facets; Taking care of oneself and the home, Work and studies, and Leisure and relaxation. The same factor structure was valid for both original scores and the residuals. An expected pattern of correlations with the indicators was mainly found, suggesting basic construct validity. No ceiling or floor effects were found. Conclusions: Taken together, the findings suggest the SDO-13 is a reliable and robust instrument that may be used to get an overview of the satisfaction people living with mental illness derive from their daily occupations.
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| 8. |
- Hartman, Henrik, et al.
(författare)
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First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
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| 9. |
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| 10. |
- Nyholm, Dag, et al.
(författare)
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Frequent administration of levodopa/carbidopa microtablets vs levodopa/carbidopa/entacapone in healthy volunteers
- 2013
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 127:2, s. 124-132
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES:An oral dispersible microtablet formulation of levodopa/carbidopa 5/1.25 mg (LC-5) was developed for individualized repeated dosing. The aim was to compare pharmacokinetic profiles of LC-5 and levodopa/carbidopa/entacapone (LCE).MATERIALS AND METHODS:A randomized, crossover study was carried out in 11 healthy subjects. Plasma concentrations of levodopa, carbidopa and 3-O-methyldopa were determined after intake of 300 mg levodopa during the day, either as three intakes of 100/25/200 mg LCE or as a morning dose of 75/18.25 mg followed by five repeated doses of 45/11.25 mg LC-5.RESULTS:Repeated dosing (2.4-hourly) with LC-5 microtablets compared to LCE (6-hourly) avoided long periods with low plasma levodopa levels. Time to maximum plasma concentrations was significantly shorter for LC-5. LC-5 showed lower fluctuation index (FI) in plasma compared to LCE (ANOVA P = 0.0028). FI for dose 2-5 was on average 1.26 for levodopa in LC-5, and 2.23 for dose 1-2 of LCE. The ratio between the two mean FI:s is 0.565; that is, LC-5 gave nearly half the FI as compared to LCE.CONCLUSIONS:Fractionation of levodopa with LC-5 into small, frequent administrations as compared to standard administrations of LCE decreased the FI in plasma for both levodopa and carbidopa by nearly half.
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