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- Blomstrand, Fredrik, 1969, et al.
(författare)
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Extent of intercellular calcium wave propagation is related to gap junction permeability and level of connexin-43 expression in astrocytes in primary cultures from four brain regions.
- 1999
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Ingår i: Neuroscience. - 0306-4522. ; 92:1, s. 255-65
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Tidskriftsartikel (refereegranskat)abstract
- Astrocytes are coupled via gap junctions, predominantly formed by connexin-43 proteins, into cellular networks. This coupling is important for the propagation of intercellular calcium waves and for the spatial buffering of K+. Using the scrape-loading/dye transfer technique, we studied gap junction permeability in rat astrocytes cultured from four different brain regions. The cultures were shown to display regional heterogeneity with the following ranking of the gap junction coupling strengths: hippocampus = hypothalamus > cerebral cortex = brain stem. Similar relative patterns were found in connexin-43 messenger RNA and protein levels using solution hybridization/RNase protection assay and western blots, respectively. The percentages of the propagation area of mechanically induced intercellular calcium waves for cortical, brain stem and hypothalamic astrocytes compared with hippocampal astrocytes were approximately 77, 42, and 52, respectively. Thus, the extent of calcium wave propagation was due to more than just gap junctional permeability as highly coupled hypothalamic astrocytes displayed relatively small calcium wave propagation areas. Incubation with 5-hydroxytryptamine decreased and incubation with glutamate increased the calcium wave propagation area in hippocampal (67% and 170% of the control, respectively) and in cortical astrocytes (82% and 163% of the control, respectively). Contrary to hippocampal and cortical astrocytes, the calcium wave propagation in brain stem astrocytes was increased by 5-hydroxytryptamine incubation (158% of control), while in hypothalamic astrocytes, no significant effects were seen. Similar effects from 5-hydroxytryptamine or glutamate treatments were observed on dye transfer, indicating an effect on the junctional coupling strength. These results demonstrate a strong relationship between connexin-43 messenger RNA levels, protein expression, and gap junction permeability among astroglial cells. Furthermore, our results suggest heterogeneity among astroglial cells from different brain regions in intercellular calcium signaling and in its differential modulation by neurotransmitters, probably reflecting functional requirements in various brain regions.
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- Eisemann, Martin, et al.
(författare)
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Attitudes towards self-determination in health care : A general population survey in northern Sweden
- 1999
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Ingår i: European Journal of Public Health. - : Oxford University Press (OUP). - 1101-1262 .- 1464-360X. ; 9:1, s. 41-44
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Tidskriftsartikel (refereegranskat)abstract
- Background: Today, patient self-determination has become an issue in many western countries due to the widespread availability and use of technology, which makes it possible to prolong life often in spite of severe disability and poor quality of life. Many people fear an overzealous use of modern life-saying procedures which merely serve to prolong the dying process. As a first step towards autonomy and increasing self-determination, advance directives (living wills) have been introduced in some countries. Methods: To survey a general population's attitudes towards advance directives and self-determination a questionnaire was mailed to a representative sample of 600 citizens in northern Sweden. Issues regarding importance of control, concerns about own health care, treatment preferences and support for and use of advance directives were addressed. Results: There was a response rate of 80% and the great majority of respondents reported that it was extremely or very important to have a say in decisions about their health care (79.5%). A significant number of subjects were concerned about either being treated too aggressively or not aggressively enough. There was a variability in treatment preferences, depending on the reversibility of the condition. Conclusions: The results demonstrate a vital interest among the Swedish general public for greater self-determination in health care, which is also reflected by their support of advance directives.
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- Karacagil, Sadettin, et al.
(författare)
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Composite polytetrafluoroethylene/vein bypass grafts : conventional distal vein segment of vein cuff?
- 1996
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Ingår i: European Journal of Vascular and Endovascular Surgery. - 1078-5884 .- 1532-2165. ; 12:3, s. 337-371
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To determine the current status of PTFE vein composite grafts, we reviewed our experience with 205 composite reconstructions and compared the results of conventional distal vein segment to that of distal vein cuff. DESIGN: Retrospective review. SETTING: Department of Surgery, University Hospital. PATIENTS AND METHODS: The series included 85 women and 102 men with a median age of 70. The indications for surgery were claudication in 30, rest pain in 71 and ulcer/gangrene in 103. The site of the distal anastomosis was the popliteal artery in 111 and crural artery in 94. The graft consisted of a proximal PTFE graft anastomosed to a distal segment of reversed saphenous vein in 169 or to a modified distal Miller cuff in 36 operations after 1992. RESULTS: Cumulative life table primary patency rates for the whole series at 12, 24 and 36 months were 39%, 32% and 25% respectively. Limbs with good run-off demonstrated significantly better patency rates compared to limbs with poor run-off (55% and 17% at 12 months, 35% and 11% at 36 months, p = 0.04). The patency rate of femorocrural grafts with poor run-off was only 4% at 12 months. The overall limb salvage rates at 12 and 36 months were 63% and 55%, respectively. Similar results were obtained in limbs with distal reversed vein segment and distal vein cuff. CONCLUSION: The results of this study suggest that for infrainguinal bypass grafting where the saphenous vein is unavailable, a composite PTFE-vein graft might be an acceptable alternative in limbs with good run-off. Although not a randomised study, the results using a distal reversed vein segment of a cuff were similar.
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- Thorlin, Thorleif, 1964, et al.
(författare)
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Delta-opioid receptors on astroglial cells in primary culture: mobilization of intracellular free calcium via a pertussis sensitive G protein.
- 1998
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Ingår i: Neuropharmacology. - 0028-3908. ; 37:3, s. 299-311
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Tidskriftsartikel (refereegranskat)abstract
- Astrocytes in primary culture from rat cerebral cortex were probed concerning the expression of delta-opioid receptors and their coupling to changes in intracellular free calcium concentrations ([Ca2+]i). Fluo-3 or fura-2 based microspectrofluorometry was used for [Ca2+]i measurements on single astrocytes in a mixed astroglial-neuronal culture. Application of the selective delta-opioid receptor agonist, [D-Pen2, D-Pen5]-enkephalin (DPDPE), at concentrations ranging from 10 nM to 100 microM, induced concentration-dependent increases in [Ca2+]i (EC50 = 114 nM). The responses could be divided into two phases, with an initial spike in [Ca2+]i followed by either oscillations or a sustained elevation of [Ca2+]i. These effects were blocked by the selective delta-opioid receptor antagonist ICI 174864 (10 microM). The expression of delta-opioid receptors on astroglial cells was further verified immunohistochemically, using specific antibodies, and by Western blot analyses. Pre-treatment of the cells with pertussis toxin (100 ng/ml, 24 h) blocked the effects of delta-opioid receptor activation, consistent with a Gi- or Go-mediated response. The sustained elevation of [Ca2+]i was not observed in low extracellular Ca2+ and was partly blocked by nifedipine (1 microM), indicating the involvement of L-type Ca2+ channels. Stimulating neurons with DPDPE resulted in a decrease in [Ca2+]i, which may be consistent with the closure of the plasma membrane Ca2+ channels on these cells. The current results suggest a role for astrocytes in the response of the brain to delta-opioid peptides and that these opioid effects in part involve altered astrocytic intracellular Ca2+ homeostasis.
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- Åberg, N David, 1970, et al.
(författare)
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Connexin43 mRNA and protein expression during postnatal development of defined brain regions.
- 1999
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Ingår i: Brain research. Developmental brain research. - 0165-3806. ; 115:1, s. 97-101
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Tidskriftsartikel (refereegranskat)abstract
- Connexin43 (cx43) mRNA and protein were quantified in seven brain regions using RNase protection assays and Western blotting from postnatal day 3, 10, and 17, and adult Sprague-Dawley rats. Increases in cx43 mRNA abundance preceded strong increases in cx43 protein in the cerebral cortex, hippocampus, hypothalamus, and striatum, whereas smaller postnatal increases were seen in the cerebellum, brain stem, and olfactory bulbs.
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- Örtegren, Jonas, et al.
(författare)
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Time-dependent nonlinear optical properties of pyroelectric liquid crystalline polymers
- 1999
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Ingår i: Macromolecular Symposia. - : Wiley. - 1022-1360 .- 1521-3900. ; 148, s. 179-195
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Tidskriftsartikel (refereegranskat)abstract
- Highly oriented pyroelectric liquid-crystalline polymers were prepared by photopolymerization under the influence of a static electric field from binary mixtures of two acrylate monomers exhibiting chiral smectic C mesomorphism. Both monomers contained nitro groups to yield second order nonlinear optical properties (second harmonic generation) and one of the monomers had two functional groups to yield a crosslinked polymer. The room temperature second order nonlinear susceptibility of the polymers showed during the first two hours a 10 % decrease after which it remained constant during the next 48 days. At elevated temperatures there was a significant difference in the nonlinear optical properties over time between crosslinked and uncrosslinked polymers. The uncrosslinked polymer showed a pronounced loss of second order nonlinear optical activity with time at ≥38°C. The crosslinked polymer showed a much smaller and basically a temperature independent decrease rate in the second order nonlinear optical properties at all the ageing temperatures (23-130°C). Both the loss in mesogen order parameter, very evident for the uncrosslinked polymer, and conformational changes occurring within the mesogens (β mechanism), may account for the observations made.
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