| 1. |
- Bellas, Juan, et al.
(author)
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Monitoring of organic compounds and trace metals during a dredging episode in the Gota Alv Estuary (SW Sweden) using caged mussels
- 2007
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In: Water Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 181:1-4, s. 265-279
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Journal article (peer-reviewed)abstract
- The concentrations of selected trace metals, organotins, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) were determined in caged blue mussels (Mytilus edulis) during dredging operations in the Gota Alv Estuary (SW Sweden). Maximum values of pollutants in mussel tissues were found after the dredging started. Our results showed that the dredging caused mobilization of organotins from the sediments to the water column during the experimental period. Multidimensional scaling (MDS) and cluster analysis were applied to compare and establish relationships between levels of pollutants in mussels and sampling sites during the experimental period. In order to evaluate the biological effects of contaminants, genotoxic damage was measured using the Comet assay, and its potential application for environmental monitoring is discussed.
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| 2. |
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| 3. |
- Magnusson, Kerstin, 1957, et al.
(author)
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Bioaccumulation of PCB congeners in marine benthic infauna
- 2006
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In: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 61:4, s. 379-395
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Journal article (peer-reviewed)abstract
- Field concentrations of polychlorinated biphenyls (PCBs) were measured in sediment and nine marine soft bottom invertebrate species. Lipid- and organic carbon normalised biota-sediment accumulation factors (BSAFs) were determined for 29 nonplanar and 11 coplanar congeners. To investigate whether the bioaccumulation was in thermodynamic equilibrium with the sediment, the determined BSAFs were compared to theoretically calculated ones to obtain a BSAF(det)/BSAF(theor)-ratio. Large interspecific variations were found: one suspension feeding and one deposit feeding species of brittle stars (Amphiura filiformis and A. chiajei), and one predatory polychaete (Glycera rouxii) had ratios > 1 for congeners with log K-ow > 6.5. In these species there was also a linear relationship between logK(ow) and BSAF, both for coplanar and for planar congeners but with lower values for coplanar ones. For other species the pattern was more scattered. Only the deposit feeding polychaete Melinna cristata had BSAF(det)/BSAF(theor)-ratios < 1 for all congeners. Thus, the interspecific variations in bioaccumulation did not correlate with differences in feeding strategies, but may be caused by differences in biotransformation, and in age and size of the analysed specimens. (c) 2005 Elsevier Ltd. All rights reserved.
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| 4. |
- Norlén, Per, et al.
(author)
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The vagus regulates histamine mobilization from rat stomach ECL cells by controlling their sensitivity to gastrin
- 2005
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In: Journal of Physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 564:3, s. 895-905
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Journal article (peer-reviewed)abstract
- The ECL cells in the oxyntic mucosa secrete histamine in response to gastrin, stimulating parietal cells to produce acid. Do they also operate under nervous control? The present study examines histamine mobilization from rat stomach ECL cells in situ in response to acute vagal excitation and to food or gastrin following vagal or sympathetic denervation. Applying the technique of microdialysis, we monitored the release of histamine by radioimmunoassay. Microdialysis probes were placed in the submucosa on either side of the stomach, 3 days before experiments. The rats were awake during microdialysis except when subjected to electrical vagal stimulation. One-sided electrical vagal stimulation raised serum gastrin and mobilized gastric histamine. However, gastrin receptor blockade prevented the histamine mobilization, indicating that circulating gastrin accounts for the response. Vagal excitation by hypoglycaemia (insulin) or pylorus ligation did not mobilize either gastrin or histamine. The histamine response to food was almost abolished by gastrin receptor blockade, and it was halved on the denervated side after unilateral subdiaphragmatic vagotomy. While the histamine response to a near-maximally effective dose of gastrin was unaffected by vagotomy, the response to low gastrin doses was reduced significantly. Abdominal ganglionic sympathectomy failed to affect the histamine response to either food or gastrin. In conclusion, gastrin is responsible for most of the food-evoked mobilization of ECL-cell histamine. The histamine response to electrical vagal stimulation reflects the effect of circulating gastrin rather than a direct action of the vagus on the ECL cells. Vagal denervation was accompanied by an impaired histamine response to food intake, probably reflecting the right-ward shift of the serum gastrin concentration-histamine response curve. The results suggest that the vagus controls the sensitivity of the ECL cells to gastrin.
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| 6. |
- Qader, Saleem, et al.
(author)
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Long-term infusion of nutrients (total parenteral nutrition) suppresses circulating ghrelin in food-deprived rats.
- 2005
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In: Regulatory Peptides. - : Elsevier BV. - 1873-1686 .- 0167-0115. ; 131:Aug 12, s. 82-88
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Journal article (peer-reviewed)abstract
- Background: Ghrelin derives from endocrine cells (A-like cells) in the stomach (mainly the oxyntic mucosa). Its concentration in the circulation increases during fasting and decreases upon re-feeding. This has fostered the notion that the absence of food in the upper gastrointestinal (GI) tract stimulates the secretion of ghrelin. The purpose of the present study was to determine the concentration of ghrelin in serum and oxyntic mucosa after replacing food with intravenous (iv) infusion of nutrients for 8 days using the technique known as total parenteral nutrition (TPN). Materials and methods: Male Sprague-Dawley rats (200-250 g) were given nutrients (lipids, glucose, amino acids, minerals and vitamins) by iv infusion for 8 days during which time they were deprived of food and water; another group was deprived of food for 24-48 h (fasted controls), while fed controls had free access to food and water. Serum ghrelin, gastrin and pancreastatin concentrations were measured together with the ghrelin content of the oxyntic mucosa. Plasma insulin and glucose as well as serum lipid concentrations were also determined. Results: Fasted rats had higher serum ghrelin than TPN rats and fed controls. The oxyntic mucosal ghrelin concentration (and content) was lower in TPN rats than in fasted rats or fed controls. The serum gastrin and pancreastatin concentrations were lower in TPN rats and fasted rats than in fed controls. The plasma insulin concentration was 87 pmol/l +/- 8 (SEM) in TPN rats compared to 101 16 pmol/l in fed controls; it was 26 14 pmol/l in fasted rats. The basal plasma glucose level was 11 +/- 0.6 mmol/l in TPN rats and 12 +/- 0.8 mmol/l in fed controls; it was 7 +/- 0.3 mmol/l in fasted rats. In TPN rats, the serum concentrations of free fatty acids, triglycerides and cholesterol were increased by 100%, 50% and 25%, respectively, compared to fed controls. Fasted rats had higher circulating concentrations of free fatty acids (20%) and lower concentrations of triglycerides (- 40%) than fed controls; fasted rats did not differ from fed controls with respect to serum cholesterol. Conclusion: The circulating ghrelin concentration is high in situations of nutritional deficiency (starvation) and low in situations of nutritional plenty (free access to food or TPN). The actual presence or absence of food in the GI tract seems irrelevant. Circulating insulin and glucose concentrations did not differ much between TPN rats and fed controls, serum lipids, however, were elevated in the TPN rats. We suggest that elevated blood lipid levels contribute to the suppression of circulating ghrelin in rats subjected to TPN for 8 days.
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