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- Agborsangaya, Calypse, et al.
(författare)
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The effects of storage time and sampling season on the stability of serum 25-hydroxy vitamin D and androstenedione
- 2010
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Ingår i: Nutrition and Cancer. - : Informa UK Limited. - 0163-5581 .- 1532-7914. ; 62:1, s. 51-57
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the stability of serum samples stored in large biobanks is pivotal for reliable assessment of hormone-dependent disease risks. We studied the effects of sample storage time and season of serum sampling on the stability of 25-hydroxy vitamin D (25-OHD) and androstenedione in a stratified random sample of 402 women, using paired sera from the Finnish Maternity Cohort. Serum samples selected were donated between 6 and 24 yr ago. The storage time did not affect serum 25-OHD and androstenedione levels. However, there was a significant mean difference in the 25-OHD levels of sera withdrawn during winter (first sample) vs. during summer (second sample; -18.4 nmol/l, P ≤ 0.001). Also at the individual level, there were significant differences in average 25-OHD levels between individuals with the paired sera taken at winter–winter compared with other alternatives (summer–winter, winter–summer, and summer–summer). The androstenedione levels showed no such differences. Long-term storage does not affect serum 25-OHD and androstenedione levels, but sampling season is an important determinant of 25-OHD levels. Stored serum samples can be used to study disease associations with both hormones. However, sampling season needs to be taken into account for 25-OHD by considering matching and stratification and, if possible, serial sampling.
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- Andersson, Britta, 1979-
(författare)
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Manipulation of potassium ion fluxes to induce apoptosis in lung cancer cells
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Apoptosis is a special form of cell death that if non-functional may lead to diseases such as cancer. A reduction of the intracellular potassium ion (K+) content is necessary for activating enzymes important for the execution of apoptosis. Pharmacological modulation of K+ fluxes to reduce intracellular K+ in cancer cells might therefore force the cells into apoptosis and decrease tumour cell mass. Human malignant pleural mesothelioma (MPM) is a form of cancer often caused by asbestos exposure. Although asbestos has been banned in the Western World, the incidence of MPM is expected to increase. Cisplatin is the first-line chemotherapy for MPM, but acquired resistance to the drug is a clinical problem. This thesis is mainly based on work with the human malignant pleural mesothelioma cell line (P31 wt) and a cisplatin-resistant sub-line (P31 res). The aim was to first characterize K+ fluxes in P31 wt and P31 res cells, and then manipulate them in order to reduce intracellular K+ and induce apoptosis with K+ manipulation alone or in combination with cisplatin. Characterization of K+ fluxes in P31 wt cells showed that: 1) ouabain, a digitalis-like drug, and specific blocker of the Na+, K+, ATPase pump, effectively inhibited K+ uptake, 2) bumetanide, a diuretic, and an inhibitor of the Na+, K+, 2Cl-¬-cotransporter, had a transient effect on K+ uptake, and 3) the antifungal drug amphotericin B stimulated K+ efflux. In order to determine intracellular K+ content, the potassium-binding fluorescent probe PBFI-AM was used in a 96-well plate assay. After a 3-h incubation with ouabain, with or without bumetanide, combined with amphotericin B, the intracellular K+ content was reduced in P31 wt cells but not in P31 res cells. Ouabain induced apoptosis in both P31 wt and P31 res cells. P31 res cells were sensitized to cisplatin by ouabain, since 10 mg/L cisplatin in combination with ouabain induced about the same percentage of apoptotic cells as 40 mg/L cisplatin. Apoptosis was executed via caspase-3 activation in both P31 wt and P31 res cells. Amphotericin B enhanced ouabain-induced apoptosis in P31 wt cells via caspase-9 activation, with increased caspase-3 activation and DNA fragmentation as consequences. Ouabain-induced apoptosis in P31 res cells was executed via increased expression of pro-apoptotic Bak. The combination of cisplatin with ouabain and amphotericin B was stressful to both P31 wt and P31 res cells, since SAPK/JNK a known factor in stress-induced apoptosis was activated. In conclusion, K+ flux manipulation with clinical used drugs can induce apoptosis per se and also enhance cisplatin-induced apoptosis in P31 wt and P31 res cells.
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- Andersson, Ulrika, et al.
(författare)
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Rapid induction of long-lasting drug efflux activity in brain vascular endothelial cells but not malignant glioma following irradiation
- 2002
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Ingår i: Medical Oncology. - 1357-0560 .- 1559-131X. ; 19:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The influence of radiotherapy on malignant glioma multidrug resistance to chemotherapy was evaluated because patients with glioma often are treated with a combination of radiotherapy and chemotherapy. Multidrug resistance gene (MDR1, mdr1a, and mdr1b) transcripts were found in human and rat glioma cell lines. P-Glycoprotein (Pgp) was immunohistochemically detected in glioma cell lines and in the rat brain vascular endothelial cell line (RBE4). A multidrug resistance pump efflux activity assay demonstrated increased calcein efflux of RBE4 endothelial cells, but not glioma cells, 2 h after irradiation and still increased 14 d after irradiation. The increased efflux was equally inhibited by verapamil with or without irradiation. In the rat intracranial glioma model (BT4C), Pgp was demonstrated in capillary endothelial cells of the tumor tissue and surrounding normal brain, but not in tumor cells. The expression of gene transcripts or Pgp was not affected by irradiation. The results indicate that long-lasting verapamil-resistant drug efflux mechanisms are activated in brain endothelial cells after irradiation. The results might explain the poor efficacy of chemotherapy following radiotherapy and contribute to consideration of new treatment strategies in the management of malignant glioma.
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| 10. |
- Baglietto, Laura, et al.
(författare)
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DNA methylation changes measured in pre-diagnostic peripheral blood samples are associated with smoking and lung cancer risk
- 2017
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 140:1, s. 50-61
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Tidskriftsartikel (refereegranskat)abstract
- DNA methylation changes are associated with cigarette smoking. We used the Illumina Infinium HumanMethylation450 array to determine whether methylation in DNA from pre-diagnostic, peripheral blood samples is associated with lung cancer risk. We used a case-control study nested within the EPIC-Italy cohort and a study within the MCCS cohort as discovery sets (a total of 552 case-control pairs). We validated the top signals in 429 case-control pairs from another 3 studies. We identified six CpGs for which hypomethylation was associated with lung cancer risk: cg05575921 in the AHRR gene (p-valuepooled = 4 × 10(-17) ), cg03636183 in the F2RL3 gene (p-valuepooled = 2 × 10 (- 13) ), cg21566642 and cg05951221 in 2q37.1 (p-valuepooled = 7 × 10(-16) and 1 × 10(-11) respectively), cg06126421 in 6p21.33 (p-valuepooled = 2 × 10(-15) ) and cg23387569 in 12q14.1 (p-valuepooled = 5 × 10(-7) ). For cg05951221 and cg23387569 the strength of association was virtually identical in never and current smokers. For all these CpGs except for cg23387569, the methylation levels were different across smoking categories in controls (p-valuesheterogeneity ≤ 1.8 x10 (- 7) ), were lowest for current smokers and increased with time since quitting for former smokers. We observed a gain in discrimination between cases and controls measured by the area under the ROC curve of at least 8% (p-values ≥ 0.003) in former smokers by adding methylation at the 6 CpGs into risk prediction models including smoking status and number of pack-years. Our findings provide convincing evidence that smoking and possibly other factors lead to DNA methylation changes measurable in peripheral blood that may improve prediction of lung cancer risk.
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