| 1. |
- Andersson, Per S., et al.
(författare)
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The isotopic composition of Nd in a boreal river : a reflection of selective weathering and colloidal transport
- 2001
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Ingår i: Geochimica et Cosmochimica Acta. - 0016-7037 .- 1872-9533. ; 65:4, s. 521-527
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Tidskriftsartikel (refereegranskat)abstract
- In this study the Nd concentrations (CNd) from 18 months of weekly sampling of filtered water (<0.45 μm) in the Kalix River, northern Sweden, are reported with εNd(0) and 147Sm/144Nd ratios determined in samples representing major flow events as well as maxima and minima in CNd. The CNd varies by a factor of ten, between 200 pmol/L to 2100 pmol/L, and there is a strong relation between high discharge and high CNd. The Nd in the Kalix River is mainly transported on particles (>90%), dominated by a colloidal phase primarily composed of organic C and Fe. The εNd(0) and 147Sm/144Nd only vary within a narrow range, -27.1 to -24.8 and 0.103 to 0.110 respectively, with no obvious relationship to CNd and discharge. The εNd(0) and 147Sm/144Nd in the river water is significantly lower than in the unweathered till and average bedrock in the catchment and show a closer resemblance with the isotopic characteristics found in humic substances and plant material. These data show that the isotopic composition of Nd exported from a large boreal drainage basin does not directly reflect that of the bulk bedrock in the catchment. The isotopic composition is controlled by selective weathering and the Nd transport is dominated by organic colloidal particles.
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| 2. |
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| 3. |
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| 4. |
- Dahlqvist, Jonas, et al.
(författare)
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Business start-up reasons and firm performance
- 2000
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Ingår i: Frontiers of entrepreneurship research 2000. - Wellesley, Mass. : Babson College. - 0910897212
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 5. |
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| 6. |
- Dahlqvist, Jonas, et al.
(författare)
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Patterns of search and the newness of venture ideas
- 2004
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Ingår i: Frontiers of Entrepreneurship Research 2004. - Welleseley, MA : Babson College. - 0910897255 ; , s. 315-326
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Dahlqvist, Per, et al.
(författare)
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Effects of postischemic environment on transcription factor and serotonin receptor expression after permanent focal cortical ischemia in rats
- 2003
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Ingår i: Neuroscience. - 1873-7544 .- 0306-4522. ; 119:3, s. 643-652
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Tidskriftsartikel (refereegranskat)abstract
- Housing rats in an enriched environment improves functional outcome after ischemic stroke, this may reflect neuronal plasticity in brain regions outside the lesion. Which components of the enriched environment that are of greatest importance for recovery after brain ischemia is uncertain. We have previously found that enriched environment and social interaction alone both improve functional recovery after focal cerebral ischemia, compared with isolated housing with voluntary wheel-running. In this study, the aim was to separate components of the enriched environment and investigate the effects on some potential mediators of improved functional recovery; such as the inducible transcription factors nerve growth factor-induced gene A (NGFI-A) and NGFI-B, and the glucocorticoid and serotonin systems. After permanent middle cerebral artery occlusion, rats were divided into four groups: individually housed with no equipment (deprived group), individually housed with free access to a running wheel (running group), housed together in a large cage with no equipment (social group) or in a large cage furnished with exchangeable bars, chains and other objects (enriched group). mRNA expression of inducible transcription factors, serotonin and glucocorticoid receptors was determined with in situ hybridisation 1 month after cerebral ischemia. Rats housed in enriched or social environments showed significantly higher mRNA expression of NGFI-A and NGFI-B in cortical regions outside the lesion and in the CA1 (cornu ammonis region of the hippocampus), compared with isolated rats with or without a running wheel. NGFI-A and NGFI-B mRNA expression in cortex and in CA1 was significantly correlated to functional outcome. 5-Hydroxytryptamine receptor 1A (5-HT1A) mRNA expression and binding, as well as 5-HT2A receptor mRNA expression were decreased in the hippocampus (CA4 region) of the running wheel rats. Mineralocorticoid receptor gene expression was increased in the dentate gyrus amongst wheel-running rats. No group differences were found in plasma corticosterone levels or mRNA levels of glucocorticoid receptor, corticotropin-releasing hormone, 5-HT2C or c-fos. In conclusion, we have found that social interaction is a major component of the enriched environment regarding the effects on NGFI-A and NGFI-B expression. These transcription factors may be important mediators of improved functional recovery after brain infarctions, induced by environmental enrichment. (C) 2003 IBRO. Published by Elsevier Science Ltd. All rights reserved.
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| 8. |
- Dahlqvist, Per, et al.
(författare)
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Environmental enrichment reverses learning impairment in the Morris water maze after focal cerebral ischemia in rats
- 2004
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Ingår i: European Journal of Neuroscience. - 0953-816X .- 1460-9568. ; 19:8, s. 2288-2298
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive impairment is common after ischemic stroke. In rodent stroke models using occlusion of the middle cerebral artery (MCA) this is reflected by impaired spatial memory associated with the size of the ischemic lesion. Housing in an enriched environment enhances brain plasticity and improves recovery of sensorimotor functions after experimental stroke in rats. In this study we report that postischemic housing in an enriched environment also attenuates the long-term spatial memory impairment after MCA occlusion and extinguishes the association between spatial memory and infarct volume. An enriched environment did not significantly alter the expression of selected neuronal plasticity-associated genes 1 month after MCA occlusion, indicating that most of the adaptive changes induced by an enriched environment have already occurred at this time point. We conclude that the attenuated memory impairment induced by environmental enrichment after MCA occlusion provides a useful model for further studies on the neurobiological mechanisms of recovery of cognitive functions after ischemic stroke.
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| 10. |
- Hertegård, Stellan, et al.
(författare)
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Cross-linked hyaluronan used as augmentation substance for treatment of glottal insufficiency : safety aspects and vocal fold function
- 2002
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Ingår i: The Laryngoscope. - : Wiley. - 0023-852X .- 1531-4995. ; 112:12, s. 2211-2219
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine safety aspects and vocal fold function after vocal fold augmentation with a cross-linked hyaluronan derivative (hylan B gel) as compared with bovine collagen. STUDY DESIGN; A prospective, randomized trial. METHODS: Eighty-three patients with glottal insufficiency were treated with injection augmentation with hylan B gel and bovine collagen and were examined at 1, 6, and 12 months after treatment. Seventy patients with unilateral vocal fold paresis (n = 35) or atrophy (n = 35) were randomly assigned to receive either hylan B gel (n = 47) or collagen (n = 23) injections into one vocal fold. Thirteen patients with glottal insufficiency caused by scar defects or paresis resulting from malignant disease were included in a nonrandomized group and were treated only with hylan B gel. Evaluations were made from patients' subjective ratings (visual analogue scales), digitized videostroboscopic measurements, phonetograms, maximum phonation time, and phonation quotients. RESULTS: Twelve months after injections, the patients' self-ratings were significantly improved for both the hylan B gel and the collagen groups. In addition, the videostroboscopic measurements showed significantly improved glottal closure for both groups. However, for the hylan B gel group, vibration amplitude and glottal area variations were preserved, and this group showed significantly less resorption at the injected vocal fold edge. Furthermore, maximum phonation time had increased significantly for the hylan B gel patients (collagen, nonsignificant). No serious adverse events were observed; three patients injected with hylan B gel had temporary inflammation at the injection site, which resolved without sequelae. CONCLUSIONS: The results showed that both hylan B gel and collagen can be safely used for injection treatment of glottal insufficiency. Both treatments resulted in significantly improved voice as rated by the patients. However, the patients treated with hylan B gel showed better vocal fold status and longer maximum phonation time at 12 months after treatment as compared with patients treated with collagen.
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