| 1. |
- Andersson, Jens A, et al.
(författare)
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Att motivera förändring
- 2004
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Ingår i: 2:a Pedagogiska Inspirationskonferensen 2004. ; , s. 9-11
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Förändringar måste vara väl motiverade och förankrade hos både elever och lärare. De måste vara anpassade till skolans mål och den enskilde studentens behov. I denna rapport presenteras ett antal förslag på lösningar till några av de problem som kan uppstå då man försöker införa nya pedagogiska metoder samt motivationens betydelse för det slutgiltiga resultatet.
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| 2. |
- Bruzelius, Katharina, et al.
(författare)
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Biosynthesis of selenoproteins in cultured bovine mammary cells.
- 2008
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Ingår i: Journal of Trace Elements in Medicine and Biology. - : Elsevier BV. - 1878-3252 .- 0946-672X. ; 22:3, s. 224-233
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Tidskriftsartikel (refereegranskat)abstract
- The biosynthesis of selenoproteins was studied in relation to milk formation and mammary cell biology by incubating the bovine mammary cell line MAC-T with (75Se)selenite. Intracellular proteins and proteins secreted into the cell culture medium were separated by 2D electrophoresis, the selenoproteins were detected by autoradiography, and the proteins were identified by MALDI-TOF. Approximately 35 75Se-containing spots were found in the cell proteins from MAC-T cells. Among them, one-third showed high intensity. The strongest spot was identified as glutathione peroxidase 1. About 20 spots were observed in protein precipitated from cell culture medium, one-third of them being distinctly visible. In an attempt to study a perturbation of the system, the effect of retinoic acid (RA) on the formation of selenoproteins was investigated. The concentration of 75Se in total cell protein was reduced by about 35% in cells cultured with RA compared with control cells, while the opposite effect was observed in protein precipitated from cell culture medium, which contained 60% more 75Se in RA-treated samples than in controls. There were also indications that RA might affect different selenoproteins in different ways. The methods described provide a promising approach for further studies of the regulation of selenoprotein formation in the mammary gland.
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| 3. |
- Bruzelius, Katharina, et al.
(författare)
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Occurrence of selenoprotein enzyme activities and mRNA in bovine mammary tissue.
- 2007
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Ingår i: Journal of Dairy Science. - 1525-3198. ; 90:2, s. 918-927
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Tidskriftsartikel (refereegranskat)abstract
- To elucidate the possible role of selenoproteins for milk formation and mammary gland physiology, the activities of selenoprotein enzymes and the expression of selenoprotein genes were studied in the bovine mammary gland. Messenger RNA was demonstrated for selenoprotein P, thioredoxin reductase 1, and for glutathione peroxidase (GPx) 1, 3, and 4. Significant differences in mRNA expression between the cows were seen for GPx 1 and GPx 3. The enzyme activity of glutathione peroxidase varied approximately 16-fold among cows, and the activity of thioredoxin reductase and the concentration of soluble Se varied approximately 6-fold among cows. There were positive correlations between glutathione peroxidase activity, thioredoxin reductase activity, and soluble Se, the correlation between glutathione peroxidase activity and soluble Se being the strongest. Furthermore, selenoprotein P expression correlated with GPx 1 mRNA expression and with soluble Se. There was also a correlation between glutathione peroxidase activity and the mRNA expression of GPx 1. The general conclusion from the data was that the activity of glutathione peroxidase and thioredoxin reductase and the mRNA expression of selenoprotein P and GPx 1 and 3 were influenced by Se status, but the expression of GPx 4 and thioredoxin reductase 1 were not. These results indicate that the Se status in mammary tissue is an important regulator of selenoprotein activity and expression, but that other factors are also in operation.
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| 4. |
- Bruzelius, Katharina, et al.
(författare)
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Regulation of selenoprotein mRNA expression by hormones and retinoic acid in bovine mammary cells.
- 2010
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Ingår i: Journal of Trace Elements in Medicine and Biology. - : Elsevier BV. - 1878-3252 .- 0946-672X. ; 24, s. 251-256
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Tidskriftsartikel (refereegranskat)abstract
- Selenium is essential for maintaining many body functions through the actions of selenoproteins. To find factors regulating selenoprotein biosynthesis in the bovine mammary cell line MAC-T, the effects of supplementation with selenite and also with retinoic acid, insulin, hydrocortisone and prolactin on the mRNA expression of a number of selenoproteins were investigated. It was found that MAC-T cells express glutathione peroxidase (GPx) 1 and 4, thioredoxin reductase 1 and selenoprotein P, but not GPx 3, which is interesting considering that GPx 3 is one of the only few selenoproteins detected in milk so far. Addition of selenite to the cell culture resulted in a large increase in GPx 1 expression and an increase in selenoprotein P expression, which is similar to the findings made in other systems investigated. Increased mRNA levels of GPx 1 were also observed in cells treated with insulin and hydrocortisone or with retinoic acid. The expression of thioredoxin reductase 1 was increased in cells treated with retinoic acid, whereas that of selenoprotein P was decreased in cells exposed to insulin. The results indicate that several hormones, selenium, and retinoic acid regulate the biosynthesis of various selenoproteins differently in the bovine mammary cell. The possible implications of the findings for processes related to milk formation and mammary carcinogenesis will need additional investigation. Further study of the detailed mechanisms involved is also necessary.
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| 5. |
- Bruzelius, Katharina
(författare)
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Selenoproteins in the Bovine Mammary Gland. Regulation of mRNA and Protein Expression
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Selenium is a micronutrient that is essential for many important life processes due to the action of the specific selenoproteins containing one or more of the 21st amino acid, selenocysteine. Twenty-five selenoprotein genes have been found in the human genome but the function of many of them is not yet known. Some of the characterised selenoproteins have, however, antioxidant properties. Selenium deficiency or low selenium status has been linked to various diseases in humans such as certain types of cancer, and a number of selenium deficiency symptoms are known in farm animals. When the concentration of selenium in the soil is low, as it is in Sweden, selenium supplements are often added to cow's feed to increase the levels of selenium in cow tissues which also leads to higher levels in milk. In the Swedish diet, cow's milk accounts for about one fifth of the selenium intake of adults. The general aims of the present study were to investigate which selenoproteins are found in bovine mammary cells and tissue, to find out how mRNA and protein expression are regulated, and to explore the possible role of selenoproteins in milk formation and mammary gland physiology. Biomarkers of selenium status and mechanisms of action of selenium supplements in cancer prevention were also reviewed. Messenger RNA (mRNA) was demonstrated for selenoprotein P, thioredoxin reductase 1 and for glutathione peroxidase (GPx) 1, 3 and 4 in bovine mammary tissue, and all but GPx 3 were also found to be expressed in the bovine mammary cell line MAC-T. It was also found that selenium status is an important regulator of selenoprotein activity and expression in bovine mammary tissue and cells, but that other factors are also involved. The effect of the vitamin A metabolite retinoic acid (RA) and the lactogenic hormones prolactin, insulin and hydrocortisone on mRNA expression of selenoproteins in MAC-T cells was also investigated. RA was found to increase the expression of GPx 1 and thioredoxin reductase 1. It was also found that insulin decreased the expression of selenoprotein P, and a combination of insulin and hydrocortisone increased the expression of GPx 1. The selenoproteome of MAC-T cells was studied by labelling with radioactive 75Se and examination by 2D electrophoresis, autoradiography and MALDI-TOF. MAC-T cells were shown to express a number of selenoproteins, the cytosolic GPx 1 being the most abundant. The effects of RA on the selenoprotein levels in the cell line were also studied. The concentration of 75Se in total cell protein was reduced in cells cultured with RA compared with control cells, and the opposite was seen in extracellular proteins. RA treatment of MAC-T cells also led to changes in the levels of several non-selenoproteins in the cells, for example, decreased levels of proteins associated with cancer, such as heat shock proteins 70:8 and 27:1, and keratin 8. Other proteins decreased in the MAC-T cells by RA may be associated with mammary gland development and milk formation. In summary, this study shows that a number of selenoproteins could be detected in bovine mammary tissue and cells. It was also demonstrated that the expression of these proteins can be affected by selenium status, retinoic acid and hormones.
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| 6. |
- Gromadzinska, Jolanta, et al.
(författare)
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Selenium and cancer: biomarkers of selenium status and molecular action of selenium supplements
- 2008
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Ingår i: European Journal of Nutrition. - : Springer Science and Business Media LLC. - 1436-6215 .- 1436-6207. ; 47:Suppl. 2, s. 29-50
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Forskningsöversikt (refereegranskat)abstract
- Background The relationship between selenium and cancer involves many different aspects. These include the forms of selenium present in the diet and in the body, their functions and mechanisms of action, and methods employed in assessing an individual's selenium nutritional status-both in general, and in epidemiological studies of the risk of cancer in relation to diet, as well as in connection with long-term trials for investigating the disease-preventive potential of selenium supplementation. Aim of the review To review different aspects on selenium metabolism, the occurrence of different selenoproteins and their use as biomarkers of selenium status, the results of intervention trials of the cancer-preventive effects of selenium supplementation, the mechanisms of action involved, together with epidemiological findings on relations between the selenium status in the body and risk of cancer. Results and conclusions The rapid advance in the knowledge of different selenoproteins and their biological functions has opened up new possibilities for the understanding of the biological effects of selenium supplementation. A wide variety of effects of different forms and doses of selenium has been observed in a number of experimental systems, and it is at present difficult to pinpoint the mechanism that may explain the positive preventive effects of selenium supplementation observed in some human long-term trials. Moreover, additional such trials are needed to define the benefits and risks of different types and doses of selenium supplements which in the future may be implemented for public health reasons. Another necessary focus for future research is a better understanding of the mechanisms by which selenium interferes with the carcinogenesis process.
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