| 1. |
- Hultberg, Björn, et al.
(författare)
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Interaction of metals and thiols in cell damage and glutathione distribution: potentiation of mercury toxicity by dithiothreitol
- 2001
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Ingår i: Toxicology. - 0300-483X. ; 156:2-3, s. 93-100
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we have investigated the effects of extracellular redox status and metal/thiol interactions on glutathione distribution in HeLa cell cultures. No effects were seen on glutathione distribution after the addition of different thiols, whereas the pro-oxidant copper ions affected glutathione distribution in several ways. The addition of dithiothreitol (DTT) but not the other thiols potentiated the effects of mercury ions on glutathione distribution and cell toxicity. In the presence of DTT, increased intra- and extracellular glutathione concentrations were noted already at 0.05 micromol/l, which was below the previously reported toxicity threshold for mercury ions in blood. Likewise DTT potentiated the effects of copper ions on glutathione distribution and cell toxicity, whereas the addition of DTT to cell cultures with a non-metal thiol reactive agent (hydroquinone) or an oxidative agent (hydrogen peroxide) did not affect glutathione distribution or cell toxicity. Thus, it seems as the synergistic effects between DTT and thiol reactive agents only apply to metal ions.
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| 2. |
- Hultberg, Björn, et al.
(författare)
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Lipoic acid increases glutathione production and enhances the effect of mercury in human cell lines.
- 2002
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Ingår i: Toxicology. - 0300-483X. ; 175:1-3, s. 103-110
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Tidskriftsartikel (refereegranskat)abstract
- Thiols are known to influence the metabolism of glutathione. In a previous study (Toxicology 156 (2001) 93) dithiothreitol (DTT) did not show any effect on intra- or extracellular glutathione concentrations in HeLa cell cultures but increased the effects of mercury ions on glutathione concentrations, whereas monothiols such as N-acetylcysteine (NAC) or glutathione did not. In the present study, we have investigated the effects of thiols as well as the interaction between thiols and mercury ions in cultures of both HeLa and hepatoma cells. Furthermore, we have added alpha-lipoic acid (LA) to the previously used test panel of thiols, since it is metabolised intracellularly to a dithiol (dihydrolipoate). The present study shows that LA increased intra- and extracellular concentrations of glutathione in both HeLa and hepatoma cell cultures. In contrast to results for HeLa cells, the presence of DTT increased the intracellular glutathione concentration in hepatoma cells. No increase of glutathione concentrations was observed in hepatoma cell cultures in the presence of the monothiols (NAC, homocysteine or glutathione) tested, in agreement with previous findings in HeLa cell cultures. The presence of dithiols, either DTT or dihydrolipoate (the metabolite of LA), increased the effects of mercury ions on glutathione concentrations in hepatoma cells, whereas monothiols such as NAC or glutathione did not, in agreement with previous findings in HeLa cells. Thus, metabolic effects of mercury ions were observed in hepatoma cells as well as in HeLa cells at a lower concentration than the supposed toxicity threshold for mercury in blood.
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| 3. |
- Lindblom, Pia, et al.
(författare)
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Peripheral effects of PTH are not altered after thyroid surgery in euthyroid patients
- 2001
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Ingår i: Hormone Research. - : S. Karger AG. - 0301-0163. ; 56:3-4, s. 105-109
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Tidskriftsartikel (refereegranskat)abstract
- Background. We have previously found decreased serum levels of both ionized calcium and 1,25(OH)(2)D and an increase in serum phosphate levels at 1 year after hemithyroidectomy. However, basal and stimulated parathyroid hormone (PTH) secretions were not altered. To investigate whether the observed biochemical changes after unilateral thyroid surgery may be due to a relative end-organ resistance to PTH, we studied the peripheral effects of infused hPTH-(1-34) in 6 patients preoperatively and 3 months after hemithyroidectomy. Methods: Serum levels of TSH, FT4 and FT3 were measured pre- and postoperatively. hPTH-(1-34) was infused at 0.9 IU/kg/h during 6 h. Blood samples for analysis of ionized calcium, intact PTH, phosphate, 25(OH)D, 1,25(OH)(2)D and urinary samples for calcium, phosphate and nephrogenous(n)-cAMP analysis were taken at baseline, when the infusion was discontinued after 6 h and at 24 h. Results: Three months after hemithyroidectomy, serum levels of FT3 were decreased and TSH levels increased. Pre- and postoperative hPTH-(1-34) infusions induced increased serum levels of ionized calcium, 1,25(OH)2D, increased urinary excretion of phosphate and elevated n-cAMP levels. The changes in the studied biochemical variables during the hPTH-(1-34) infusions did not differ between the two study occasions. Conclusion: By using a 6-hour hPTH-(1-34) infusion protocol, we have shown that the peripheral PTH effect is not altered by a slight reduction in thyroid hormone levels at 3 months after hemithyroidectomy.
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| 4. |
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| 5. |
- Valdemarsson, Stig, et al.
(författare)
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Evaluation of surgery for acromegaly: role of intraoperative growth hormone measurement?
- 2001
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 61:6, s. 459-470
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Intraoperative growth hormone (GH ) measurement has earlier been tried to improve surgery for acromegaly. We calculated GH half-life after adenomectomy and evaluated the possible role of this variable in predicting the final outcome of pituitary surgery in 28 consecutive patients with acromegaly. The sensitivity, specificity and predictive values were determined in relation to the results from GH suppression during an oral glucose load and IGF-1 3 months postoperatively. The GH half-life data were also compared to the corresponding results obtained from GH measurements between 60 min and 180 min after adenomectomy, and early, within 1 week, postoperatively. RESULTS: GH half-life < or =31 min was recorded in 8/13 cured patients but also in 2/15 unsuccessful cases. A mean GH concentration < or =4.4 mU/L between 60 min and 120 min after adenomectomy was found in 11/13 cured subjects but also in 3/15 not cured patients. A mean GH < or =4.0 mU/L between 90 min and 180 min was found in 11/13 cured and in 4/15 not cured patients. A mean early postoperative GH concentration < or =2.6 mU/L was noted in all 13 cured patients, but also in 2/13 unsuccessful cases. The specificity of early postoperative GH < or = 2.6 mU/L was 100% compared to 62% for a GH half-life < or =31 min (p<0.05) and 85% for the GH mean values between 60 min and 120 min and 90 min and 180 min, respectively. The sensitivity for persistent disease of values above the four cut-off limits used was between 73% and 87%. The positive predictive value for a mean early postoperative GH value >2.6 mU/L was 100%, and 72% for a GH half-life >31 min (n.s.). CONCLUSION: Although intraoperative GH half-life might be useful in some cases, it was not a reliable tool for predicting outcome of pituitary surgery in acromegaly. In cases with a 51% decrease of a basal GH concentration >5.5 mU/L, mean GH values < or =4 to < or =4.4 mU/L late intraoperatively were more informative but not as good as those obtained from the mean of a series of GH values drawn on one occasion within 1 week postoperatively, offering a 100% specificity for cure if < or =2.6 mU/L. Intraoperative GH half-life measurements should therefore be used with caution. The predictive values of the cut-off limits used in this study should be further evaluated before general application.
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| 6. |
- Akkurt, I, et al.
(författare)
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Photoneutron yields from tungsten in the energy range of the giant dipole resonance
- 2003
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 48:20, s. 3345-3352
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Tidskriftsartikel (refereegranskat)abstract
- Photoneutron production on the nuclei of high-Z components of medical accelerator heads can lead to a significant secondary dose during a course of bremsstrahlung radiotherapy, However, a quantitative evaluation of secondary neutron dose requires improved data on the photoreaction yields. These have been measured as a function of photon energy, neutron energy and neutron angle for W-nat, using tagged photons at the MAX-Lab photonuclear facility in Sweden. This work presents neutron yields for W-nat(gamma, n) and compares these with the predictions of the Monte Carlo code MCNP-GN, developed specifically to simulate photoneutron production at medical accelerators.
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| 7. |
- Anders, Isaksson, 1965-, et al.
(författare)
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Institutional theory and contracting in venture capital : the Swedish experience
- 2004
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Ingår i: Venture Capital. - London : Taylor & Francis. - 1369-1066 .- 1464-5343. ; 6:1, s. 47-71
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Tidskriftsartikel (refereegranskat)abstract
- This paper tests the tenets of institutional theory by means of an empirical study of the contractual strategies applied in the Swedish venture capital industry. Venture capitalists differ in, for example, their preferences for early or later stage investments. Some have more experience than others and some are employed by public funds while others work in non-public funds. The sector, however, was expected to be relatively homogeneous due to the small size of the industry and the cultural milieu in which it is located. This homogeneity was tested regarding the use of contractual strategies among venture capitalists in Sweden. Seventy-nine separate contractual covenants were examined in relation to distinctive sector variables, structure, experience and investment preferences. The results indicate that the greatest differences in contractual strategies occur among those with differing investment preferences. There appear to be two distinct venture capital cultures controlling contractual choices in these groups. The public and the non-public sector have limited variations in their contractual choices, although public funds employ slightly more standardized strategies. Little difference was found between the contractual choices made by experienced and inexperienced venture capitalists. The findings generally conform to the outcomes predicted by institutional theory.
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| 8. |
- Banér, Johan, et al.
(författare)
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Parallel gene analysis with allele-specific padlock probes and tag microarrays
- 2003
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Ingår i: Nucleic Acids Research. - 0305-1048 .- 1362-4962. ; 31:17, s. e103-
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Tidskriftsartikel (refereegranskat)abstract
- Parallel, highly specific analysis methods are required to take advantage of the extensive information about DNA sequence variation and of expressed sequences. We present a scalable laboratory technique suitable to analyze numerous target sequences in multiplexed assays. Sets of padlock probes were applied to analyze single nucleotide variation directly in total genomic DNA or cDNA for parallel genotyping or gene expression analysis. All reacted probes were then co-amplified and identified by hybridization to a standard tag oligonucleotide array. The technique was illustrated by analyzing normal and pathogenic variation within the Wilson disease-related ATP7B gene, both at the level of DNA and RNA, using allele-specific padlock probes.
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