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| 2. |
- Ozden, C., et al.
(författare)
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FDG Uptake in the Basal Forebrain as Measured by Digital High-Resolution PET Is a Promising Marker of Basal Forebrain Degeneration in the Lewy Body Disease Spectrum A Pilot Study
- 2020
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Ingår i: Clinical Nuclear Medicine. - : Ovid Technologies (Wolters Kluwer Health). - 0363-9762 .- 1536-0229. ; 45:4, s. 261-266
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Cognitive decline in diseases of the Lewy body spectrum (LBS) is linked to dysfunction/degeneration of the basal forebrain (BF). Assessment of glucose metabolism in the BF by FDG PET is hampered by the small size of the BF and limited spatial resolution of conventional PET. This pilot study tested the feasibility of assessing BF glucose metabolism by high-resolution digital PET (dPET). Patients and Methods The retrospective study included 12 LBS patients (61-86 years, 5 demented). Whole-brain stereotactic normalization to anatomical standard space was followed by local stereotactic normalization of a 7 x 7 x 7-cm(3) box around the BF to a custom-made 1 x 1 x 1-mm(3) FDG dPET template. FDG uptake was scaled voxelwise to mean FDG uptake in the pons. Scaled FDG uptake in the BF was compared between demented and nondemented LBS patients and tested for correlation with cortical FDG uptake. Results Scaled FDG uptake in the BF was significantly lower in demented compared with nondemented patients (1.14 +/- 0.09 vs 1.25 +/- 0.06, P = 0.031). Brain-wide voxel-based testing for correlations with scaled FDG uptake in the BF revealed a large cluster comprising medial and ventrolateral frontal cortex, anterior cingulate cortex, insular cortex, and striatum as well as smaller clusters in motor cortex and occipital cortex (P < 0.001, uncorrected). Conclusions These results suggest that dementia-associated BF degeneration in LBS can be sensitively measured as reduced BF FDG uptake on dPET. More accurate delineation of the BF based on individual high-resolution MRI might be useful to make optimal use of improved spatial resolution of dPET and to correct for possible disease- and age-dependent partial volume effects.
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| 4. |
- Struyf, E., et al.
(författare)
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The Role of Vegetation in the Okavango Delta Silica Sink
- 2015
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Ingår i: Wetlands (Wilmington, N.C.). - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 35:1, s. 171-181
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Tidskriftsartikel (refereegranskat)abstract
- We assessed the role of vegetation and hydrology in the Si cycle in the Okavango Delta. Our results show a large storage of biogenic Si (BSi) in vegetation and the sediments. The biological storage is among the highest observed so far for any ecosystem worldwide. Floodplain vegetation accumulates similar amounts of BSi in both the temporary floodplains and the permanent floodplains, with most values observed between 20 and 100 g Si m(-2). This vegetation Si, after litterfall, contributes to a large biogenic Si storage in the sediments. In temporary floodplains, sediments contain less BSi (375-1950 g Si m(-2) in the top 5 cm) than in the permanent floodplains (1950-3600 g Si m(-2) in the top 5 cm). BSi concentrations in the floodplain sediments decline exponentially indicating rapid dissolution. In the occasional and seasonal floodplains, unidirectional solute transfer from floodplains to the islands will remove Si from the riverine systems. Our work clearly emphasizes the crucial role of floodplains and wetlands in Si transport through tropical rivers, and the potential interference of hydrology with this role.
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| 5. |
- Chi Fru, Ernest, et al.
(författare)
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Biogenicity of an Early Quaternary iron formation, Milos Island, Greece
- 2015
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Ingår i: Geobiology. - : Wiley. - 1472-4677 .- 1472-4669. ; 13:3, s. 225-244
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Tidskriftsartikel (refereegranskat)abstract
- A ~2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a ~5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk δ13C isotopic compositions lower than -25‰ provide evidence for biological contribution by the Calvin and reductive acetyl–CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of ~0.04 wt.% combined with δ34S estimates of up to ~18‰ point to a non-sulphidic depository. Positive δ30Si records of up to +0.53‰ in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative δ30Si data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs.
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| 7. |
- Frings, Oliver, et al.
(författare)
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Prognostic Significance in Breast Cancer of a Gene Signature Capturing Stromal PDGF Signaling
- 2013
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Ingår i: American Journal of Pathology. - : Elsevier BV. - 0002-9440 .- 1525-2191. ; 182:6, s. 2037-2047
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we describe a novel gene expression signature of platelet-derived growth factor (PDGF) activated fibroblasts, which is able to identify breast cancers with a PDGF-stimulated fibroblast stroma and displays an independent and strong prognostic significance. Global gene expression was compared between PDGF-stimulated human fibroblasts and cultured resting fibroblasts. The most differentially expressed genes were reduced to a gene expression signature of 113 genes. The biological significance and prognostic capacity of this signature were investigated using four independent clinical breast cancer data sets. Concomitant high expression of PDGF beta receptor and its cognate Ligands is associated with a high PDGF signature score. This supports the notion that the signature detects tumors with PDGF-activated stroma. Subsequent analyses indicated significant associations between high PDGF signature score and clinical characteristics, including human epidermal growth factor receptor 2 positivity, estrogen receptor negativity, high tumor grade, and large tumor size. A high PDGF signature score is associated with shorter survival in univariate analysis. Furthermore, the high PDGF signature score acts as a significant marker of poor prognosis in multivariate survival analyses, including classic prognostic markers, Ki-67 status, a proliferation gene signature, or other recently described stroma-derived gene expression signatures.
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| 8. |
- Kos, O., et al.
(författare)
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Elevated serum soluble CD200 and CD200R as surrogate markers of bone loss under bed rest conditions
- 2014
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Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 60, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- CD200 is a transmembrane protein that belongs to the immunoglobulin family of proteins and is ubiquitously expressed on a variety of cell types. Upon interaction with its receptors (CD200Rs) expressed on myeloid-derived cells and T lymphocytes, an immunoregulatory signal is delivered to receptor-expressing cells. Previous studies have implicated a role for CD200:CD200R in the regulation of the expression of mRNA markers of osteoclastogenesis/osteoblastogenesis, following interaction of CD200 (on osteoblast precursors) with CD200R1 (on osteoclast precursors). Signaling of CD200R1 is hypothesized to attenuate osteoclastogenesis. We have investigated whether levels of soluble forms of CD200 and/or CD200R1 (sCD200, sCD200R1) are altered in volunteers undergoing 6° head down tilt bed rest to mimic conditions of microgravity known to be associated with preferential osteoclastogenesis and whether countermeasures, reported to be beneficial in attenuation of bone loss under microgravity conditions, would lead to altered sCD200 and sCD200R1 levels. Our data suggest that, as predicted, sCD200 levels fall under bed rest conditions while sCD200R1 levels rise. In subjects undergoing 30-minute per day continuous centrifugation protocols, as a countermeasure to attenuate changes which may lead to bone loss, these alterations in sCD200 and sCD200R1 levels seen under conditions of bed rest were abolished or attenuated. Our results suggest that measurement of sCD200 and/or sCD200R1 may prove a useful and rapid means of monitoring subjects at risk of bone loss and/or accessing the efficacy of treatment regimes designed to counter bone loss.
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| 11. |
- Paulsson, J., et al.
(författare)
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High expression of stromal PDGFR beta is associated with reduced benefit of tamoxifen in breast cancer
- 2017
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Ingår i: Journal of Pathology Clinical Research. - : Wiley. - 2056-4538. ; 3:1, s. 38-43
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Tidskriftsartikel (refereegranskat)abstract
- Cancer-associated fibroblasts (CAFs) regulate tumour growth, metastasis and response to treatment. Recent studies indicate the existence of functionally distinct CAF subsets. Suggested mechanisms whereby CAFs can impact on treatment response include paracrine signalling affecting cancer cell drug sensitivity and effects on tumour drug uptake. PDGFR beta is an important regulator of fibroblasts. Experimental studies have linked PDGFR beta-positive fibroblasts to metastasis and also to reduced tumour drug uptake. This study has investigated the potential role of PDGFR beta-positive fibroblasts in response to adjuvant tamoxifen treatment of breast cancer. Analyses of two breast cancer collections from randomised studies analysing adjuvant tamoxifen treatment in early breast cancer demonstrated significant benefit of tamoxifen in the group with low stromal PDGFR beta, which was not observed in the group with high stromal PDGFR beta. In general terms these findings provide novel evidence, derived from analyses of randomised clinical studies, of response-predictive capacity of a marker-defined subset of CAFs and, more specifically, identify stromal PDGFR beta as a marker related to tamoxifen benefit in early breast cancer.
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| 12. |
- Paulsson, Janna, et al.
(författare)
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High expression of stromal PDGFRß is associated with reduced benefit of tamoxifen in breast cancer
- 2017
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Ingår i: The journal of pathology. Clinical research. - : Wiley-Blackwell. - 2056-4538. ; 3:1, s. 38-43
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Tidskriftsartikel (refereegranskat)abstract
- Cancer-associated fibroblasts (CAFs) regulate tumour growth, metastasis and response to treatment. Recent studies indicate the existence of functionally distinct CAF subsets. Suggested mechanisms whereby CAFs can impact on treatment response include paracrine signalling affecting cancer cell drug sensitivity and effects on tumour drug uptake. PDGFRß is an important regulator of fibroblasts. Experimental studies have linked PDGFRß-positive fibroblasts to metastasis and also to reduced tumour drug uptake. This study has investigated the potential role of PDGFRß-positive fibroblasts in response to adjuvant tamoxifen treatment of breast cancer. Analyses of two breast cancer collections from randomised studies analysing adjuvant tamoxifen treatment in early breast cancer demonstrated significant benefit of tamoxifen in the group with low stromal PDGFRß, which was not observed in the group with high stromal PDGFRß. In general terms these findings provide novel evidence, derived from analyses of randomised clinical studies, of response-predictive capacity of a marker-defined subset of CAFs and, more specifically, identify stromal PDGFRß as a marker related to tamoxifen benefit in early breast cancer.
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| 13. |
- Roelofs, J., et al.
(författare)
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Fear of movement and (re)injury in chronic musculoskeletal pain : evidence for an invariant two-factor model of the Tampa Scale for Kinesiophobia across pain diagnoses and Dutch, Swedish, and Canadian samples
- 2007
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Ingår i: Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0304-3959 .- 1872-6623. ; 131:1-2, s. 181-190
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the current study were twofold. First, the factor structure, reliability (i.e., internal consistency), and validity (i.e., concurrent criterion validity) of the Tampa Scale for Kinesiophobia (TSK), a measure of fear of movement and (re)injury, were investigated in a Dutch sample of patients with work-related upper extremity disorders (study 1). More specifically, examination of the factor structure involved a test of three competitive models: the one-factor model of all 17 TSK items, a one-factor model of the TSK (Woby SR, Roach NK, Urmston M, Watson P. Psychometric properties of the TSK-11: a shortened version of the Tampa Scale for Kinesiophobia. Pain 2005;117:137-44.), and a two-factor model of the TSK-11. Second, invariance of the aforementioned TSK models was examined in patients with chronic musculoskeletal pain conditions (i.e., work-related upper extremity disorders, chronic low back pain, fibromyalgia, osteoarthritis) from The Netherlands, Sweden, and Canada was assessed (study 2). Results from study 1 showed that the two-factor model of the TSK-11 consisting of 'somatic focus' (TSK-SF) and 'activity avoidance' (TSK-AA) had the best fit. The TSK factors showed reasonable internal consistency, and were modestly but significantly related to disability, supporting the concurrent criterion validity of the TSK scales. Results from study 2 showed that the two-factor model of the TSK-11 was invariant across pain diagnoses and Dutch, Swedish, and Canadian samples. Altogether, we consider the TSK-11 and its two subscales a psychometrically sound instrument of fear of movement and (re)injury and recommend to use this measure in future research as well as in clinical settings. © 2007 International Association for the Study of Pain.
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| 14. |
- Yang, M., et al.
(författare)
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Puddle-Induced Resistance Oscillations in the Breakdown of the Graphene Quantum Hall Effect
- 2016
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 117:23
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Tidskriftsartikel (refereegranskat)abstract
- We report on the stability of the quantum Hall plateau in wide Hall bars made from a chemically gated graphene film grown on SiC. The v = 2 quantized plateau appears from fields B similar or equal to 5 T and persists up to B similar or equal to 80 T. At high current density, in the breakdown regime, the longitudinal resistance oscillates with a 1/B periodicity and an anomalous phase, which we relate to the presence of additional electron reservoirs. The high field experimental data suggest that these reservoirs induce a continuous increase of the carrier density up to the highest available magnetic field, thus enlarging the quantum plateaus. These in-plane inhomogeneities, in the form of high carrier density graphene pockets, modulate the quantum Hall effect breakdown and decrease the breakdown current.
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