| 1. |
- Bränström, Robert, et al.
(author)
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Electrical short-circuit in β-cells from a patient with non-insulinoma pancreatogenous hypoglycemic syndrome (NIPHS) : a case report
- 2010
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In: Journal of Medical Case Reports. - : Springer Science and Business Media LLC. - 1752-1947. ; 4:1, s. 315-
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Journal article (peer-reviewed)abstract
- INTRODUCTION: Non-insulinoma pancreatogenous hypoglycemic syndrome is a rare disorder among adults, and, to our knowledge, only about 40 cases have been reported in the literature. CASE PRESENTATION: The patient is a previously healthy 35-year-old Caucasian man. His symptoms began four years ago when he suddenly felt weakness in his legs and started sweating for unknown reasons. The symptoms worsened, and laboratory tests revealed hypoglycemia and hyperinsulinemia at the time of the symptoms. All diagnostics attempts using magnetic resonance imaging, computed tomography, and endoscopic ultrasound did not reveal any abnormalities. At this stage, surgical intervention was planned, and a distal 80% pancreatectomy was performed. The histopathologic and immunohistochemical investigations of the pancreas showed an increased number of islets of different sizes, more or less evenly distributed in the gland, but no insulinoma. Patch-clamp recordings from isolated pancreatic β-cells showed that, even at a low glucose concentration (3 mmol/L), the β-cell membrane was depolarized, and action potentials were seen. Surprisingly, in patch-clamp experiments, the addition of diazoxide had a marked effect on K-ATP channel activity and membrane potential, but no effect on insulin levels in vivo before surgery. CONCLUSION: This case report adds new information on the pathogenesis of non-insulinoma pancreatogenous hypoglycemic syndrome, as we performed an electrophysiologic characterization of isolated islet cells. We show, for the first time, that β-cells isolated from a non-insulinoma pancreatogenous hypoglycemic syndrome patient are constantly depolarized, even at low glucose levels, but display normal K-ATP channel physiology.
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| 2. |
- Bergenstråhle-Wohlert, Malin, et al.
(author)
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Concentration enrichment of urea at cellulose surfaces : results from molecular dynamics simulations and NMR spectroscopy
- 2012
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 19:1, s. 1-12
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Journal article (peer-reviewed)abstract
- A combined solid-state NMR and Molecular Dynamics simulation study of cellulose in urea aqueous solution and in pure water was conducted. It was found that the local concentration of urea is significantly enhanced at the cellulose/solution interface. There, urea molecules interact directly with the cellulose through both hydrogen bonds and favorable dispersion interactions, which seem to be the driving force behind the aggregation. The CP/MAS (13)C spectra was affected by the presence of urea at high concentrations, most notably the signal at 83.4 ppm, which has previously been assigned to C4 atoms in cellulose chains located at surfaces parallel to the (110) crystallographic plane of the cellulose I beta crystal. Also dynamic properties of the cellulose surfaces, probed by spin-lattice relaxation time (13)CT (1) measurements of C4 atoms, are affected by the addition of urea. Molecular Dynamics simulations reproduce the trends of the T (1) measurements and lends new support to the assignment of signals from individual surfaces. That urea in solution is interacting directly with cellulose may have implications on our understanding of the mechanisms behind cellulose dissolution in alkali/urea aqueous solutions.
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| 3. |
- Berglund, Erik, et al.
(author)
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Evidence for Ca2+-regulated ATP release in gastrointestinal stromal tumors
- 2013
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In: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 319:8, s. 1229-1238
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Journal article (peer-reviewed)abstract
- Gastrointestinal stromal tumors (GISTs) are thought to originate from the electrically active pacemaker cells of the gastrointestinal tract. Despite the presence of synaptic-like vesicles and proteins involved in cell secretion it remains unclear whether GIST cells possess regulated release mechanisms. The GIST tumor cell line GIST882 was used as a model cell system, and stimulus-release coupling was investigated by confocal microscopy of cytoplasmic free Ca2+ concentration ([Ca(2+)1](i)), flow cytometry, and luminometric measurements of extracellular ATP. We demonstrate that GIST cells have an intact intracellular Ca2+-signaling pathway that regulates ATP release. Cell viability and cell membrane integrity was preserved, excluding ATP leakage due to cell death and suggesting active ATP release. The stimulus-secretion signal transduction is at least partly dependent on Ca2+ influx since exclusion of extracellular Ca2+ diminishes the ATP release. We conclude that measurements of ATP release in GISTs may be a useful tool for dissecting the signal transduction pathway, mapping exocytotic components, and possibly for the development and evaluation of drugs. Additionally, release of ATP from GISTs may have importance for tumor tissue homeostasis and immune surveillance escape.
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| 4. |
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| 5. |
- Berglund, Olof, et al.
(author)
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Persistent organic pollutants in river food webs: influence of trophic position and degree of heterotrophy
- 2005
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In: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 62:9, s. 2021-2032
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Journal article (peer-reviewed)abstract
- We investigated how the degree of autotrophy/heterotrophy and organism trophic position influenced the bioaccumulation of polychlorinated biphenyls (PCBs) in 10 benthic river food webs consisting of terrestrial detritus, periphyton, invertebrates, and age-0 brown trout (Salmo trutta) in southern Sweden. Concentrations of PCBs increased with trophic position, estimated from delta(15)N and delta(13)C, on a dry weight basis (ng center dot g(-1) dry weight) but not on a lipid weight basis (ng center dot g(-1) lipid). PCB biomagnification factors between the first and second trophic levels (invertebrates/ periphyton and invertebrates/detritus) ranged between 0.3 and 2.3 and between the second and third levels (trout/invertebrates) between 0.3 and 2.0 on a lipid weight basis. The mean proportion of carbon ultimately derived from terrestrial sources, alpha, was 0.82 +/- 0.19 for invertebrates and 0.67 +/- 0.28 for trout. Contrary to our hypothesis, PCB concentrations in trout were positively related to alpha (r(2) = 0.58-0.77, p < 0.05). As alpha and the periphyton density (g C center dot m(-2)) in the rivers was positively related (r(2) = 0.88, p < 0.01), we propose that this relationship was due to an increased retention and exposure of PCBs to trout in rivers with low grazing pressure and high periphyton density.
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| 6. |
- Holmqvist, Niklas, et al.
(author)
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Lake trophic status and bioaccumulation of polychlorinated biphenyls in benthic organisms: a comparison between littoral and profundal invertebrates
- 2005
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In: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 62:6, s. 1201-1209
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Journal article (peer-reviewed)abstract
- We investigated the influence of lake trophic status on accumulation of polychlorinated biphenyls (PCBs) in littoral and profundal invertebrates from 19 lakes in southern Sweden. The PCB concentration in profundal chironomids (Chironomus sp.) was negatively correlated with lake trophy but the concentration in littoral crayfish (Pacifasticus leniusculus) was unrelated to shifting nutrient regimes. PCB concentrations in chironomids were negatively correlated, while crayfish did not correlate with lake total phosphorus. Two findings indicate that different processes determine bioaccumulation in littoral and profundal invertebrates: (i) a lack of correlation between PCB concentrations in crayfish and chironomids within lakes and (ii) some differences in congener distribution in the two species. We suggest a possible explanation in that chironomids are directly exposed to settling material from the pelagic zone, while crayfish are omnivorous and feed mainly in the littoral zone. A intensive investigation on one pond population could not reveal any individual factors, such as lipid content, size, or sex, influencing bioaccumulation of PCBs in crayfish.
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| 7. |
- Holmqvist, Niklas, et al.
(author)
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Low levels of persistent organic pollutants (POPS) in New Zealand eels reflect isolation from atmospheric sources
- 2006
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In: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 141:3, s. 532-538
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Journal article (peer-reviewed)abstract
- Polychlorinated biphenyls (PCBs) and organic pesticides (i.e., DDTs) were measured in long finned eels (Anguilla dieffenbachii) in 17 streams on the west coast of South Island, New Zealand. Very low levels of PCBs and low levels of ppDDE were found. The concentrations of PCBs and ppDDE were not correlated within sites indicating that different processes determined the levels of the two pollutants in New Zealand eels. The PCBs probably originate from atmospheric transport, ppDDE levels are determined by land use and are higher in agriculture areas. The low contamination level of these aquatic systems seems to be a function of a low input from both long and short-range transport as well as few local point sources. No correlation could be found between lipid content and persistent organic pollutants (POPs) concentration (as shown in previous studies) in the eels which could be explained by low and irregular intake of the pollutants.
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| 8. |
- Holmqvist, Niklas, et al.
(author)
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Persistent organic pollutants (POP) in a benthic omnivore - A comparison between lake and stream crayfish populations
- 2007
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In: Chemosphere. - : Elsevier BV. - 1879-1298 .- 0045-6535. ; 66:6, s. 1070-1078
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Journal article (peer-reviewed)abstract
- We investigated the accumulation of PCB and DDT in crayfish populations in 10 streams in southern Sweden. The results were compared with an earlier study on crayfish in lakes from the same area. We found that the concentration of pollutants in crayfish did not differ between the two types of systems. Variation in body burden was higher in stream living crayfish probably because of the higher influence from pollutants deposited in the catchment area and the more dynamic transport in streams. In streams, pp'-DDE concentrations were positively correlated to trophic status (total phosphorous) while PCB did not show any correlation with the nutrient regime. Further, mean Sigma PCB and p,p'-DDE concentrations in crayfish did not correlate in streams. We suggest that the sources of the two pollutants differ for stream living crayfish. The results indicate that crayfish in streams are affected to a higher degree to pollutants in the catchment area and the precipitation regime. In lakes, internal processes govern uptake of pollutants in crayfish.
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| 9. |
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| 10. |
- Larsson, Per, et al.
(author)
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Heavy metals and stable isotopes in a benthic omnivore in a trophic gradient of lakes
- 2007
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In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 41:17, s. 5973-5979
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Journal article (peer-reviewed)abstract
- Heavy metals (Cd, Hg, and Pb) and stable isotopes (N-15, C-13) in crayfish (Pacifastacus leniusculus) were studied in a trophic gradient of lakes (N = 19) in southern Sweden. Trophic indicators of the lakes as total phosphorus (tot-P) varied from 5 to 93 mu g/L. The examined lakes had no known point sources of heavy metals, but the catchment areas varied from mainly forested to agricultural land. Cd and Hg in crayfish were affected by the trophic status of the lakes, showing significant negative relationship with tot-P, total nitrogen, and chlorophyll A content and a positive relationship with lake transparency (Secchi depth). The concentration of these two heavy metals was thus higher in crayfish in the oligotrophic lakes and decreased linearly to the eutrophic ones. Pb was not related to any lake variable. Stable isotopes of carbon (delta C-13) and nitrogen (615N) in crayfish were a reflection of that found in the sediment as shown by positive linear relationships for the lakes. In the sediment of the lakes, delta C-13 signature showed significant negative relationships with the trophic indicators but positive results were shown for lake transparency. The trophic gradient of the lakes was reflected by delta C-13 in the sediment and in the crayfish. 615N in crayfish was a reflection of 615N in the sediment but the relationship was not coupled to the trophic statue of the lakes. The results from the study show that Cd and Hg in benthic omnivores as crayfish are affected by ecological processes in lakes, such as eutrophication. Stable isotopes, such as 13C and 15 N, can be used to study these ecological processes.
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