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| 2. |
- Danielsson, Anna, et al.
(författare)
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Short-Term Overeating Induces Insulin Resistance in Fat Cells in Lean Human Subjects
- 2009
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Ingår i: Molecular Medicine. - : Springer Science and Business Media LLC. - 1076-1551 .- 1528-3658. ; 15:7-8, s. 228-234
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Tidskriftsartikel (refereegranskat)abstract
- Insulin resistance and type 2 diabetes (T2D) are closely linked to obesity. Numerous prospective studies have reported on weight gain, insulin resistance, and insulin signaling in experimental animals, but not in humans. We examined insulin signaling in adipocytes from lean volunteers, before and at the end of a 4-wk period of consuming a fast-food, high-calorie diet that led to weight gain. We also examined adipocytes from patients with T2D. During the high-calorie diet, subjects gained 10% body weight and 19% total body fat, but stayed lean (body mass index = 24.3 kg/m2) and developed moderate systemic insulin resistance. Similarly to the situation in T2D subjects, in subjects on the high-calorie diet, the amount of insulin receptors was reduced and phosphorylation of IRS1 at tyrosine and at serine-307 (human sequence, corresponding to murine serine-302) were impaired. The amount of insulin receptor substrate protein-1 (IRS1) and the phosphorylation of IRS1 at serine-312 (human sequence, corresponding to murine serine-307) were unaffected by the diet. Unlike the T2D subjects, in subjects on the high-calorie diet, likely owing to the ongoing weight-gain, phosphorylation of MAP-kinases ERK1/2 became hyperresponsive to insulin. To our knowledge this study is the first to investigate insulin signaling during overeating in humans, and it demonstrates that T2D effects on intracellular insulin signaling already occur after 4 wks of a high-calorie diet and that the effects in humans differ from those in laboratory animals.
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| 3. |
- Ihalainen, Saara, et al.
(författare)
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Proteome analysis of cultivated vascular smooth muscle cells from a CADASIL patient
- 2007
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Ingår i: Molecular Medicine. - 1076-1551 .- 1528-3658. ; 13:5-6, s. 305-314
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a vascular dementing disease caused by mutations in NOTCH3 gene, a majority of which are missense mutations leading to an uneven number of cysteine residues in epidermal growth factor like repeats in the extracellular domain of Notch3 receptor (N3ECD). Disease is characterized by degeneration of vascular smooth muscle cells (VSMC) and accumulation of N3ECD on the VSMCs of small and middle-sized arteries. Recent studies have demonstrated that impairment of Notch3 signaling is not the primary cause of the disease. In the present study we have characterized the protein expression pattern of a unique material of genetically genuine cultured human CADASIL VSMCs by proteomic analysis. We identified 11 differentially expressed proteins, which are involved in protein degradation and folding, contraction of VSMCs and cellular stress. Based on the results the misfolding of Notch3 seems to cause endoplasmic reticulum stress and activation of unfolded protein response leading to increased reactive oxygen species and inhibition of cell proliferation. In addition, upregulation of contractile proteins suggests an alteration in the signalling system of VSMC contraction. The accumulation of the N3ECD on the cell surface possibly upregulates the angiotensin II regulatory feedback loop and thereby enhances the readiness of the cells to respond to angiotensin II stimulation.
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| 4. |
- Nordquist, Jenny, et al.
(författare)
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Transcription factors in muscle atrophy caused by blocked neuromuscular transmission and muscle unloading in rats
- 2007
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Ingår i: Molecular Medicine. - 1076-1551 .- 1528-3658. ; 13:9-10, s. 461-470
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Tidskriftsartikel (refereegranskat)abstract
- The muscle wasting associated with long-term intensive care unit (ICU) treatment has a negative effect on muscle function resulting in prolonged periods of rehabilitation and a decreased quality of life. To identify mechanisms behind this form of muscle wasting, we have used a rat model designed to mimic the conditions in an ICU. Rats were pharmacologically paralyzed with a postsynaptic blocker of neuromuscular transmission, and mechanically ventilated for one to two weeks, thereby unloading the limb muscles. Transcription factors were analyzed for cellular localization and nuclear concentration in the fast-twitch muscle extensor digitorum longus (EDL) and in the slow-twitch soleus. Significant muscle wasting and upregulation of mRNA for the ubiquitin ligases MAFbx and MuRF1 followed the treatment. The IκB family–member Bcl-3 displayed a concomitant decrease in concentration, suggesting altered κB controlled gene expression, although NFκB p65 was not significantly affected. The nuclear levels of the glucocorticoid receptor (GR) and the thyroid receptor α1 (TRα1) were altered and also suggested as potential mediators of the MAFbx- and MuRF1-induction in the absence of induced Foxo1. We believe that this model, and the strategy of quantifying nuclear proteins, will provide a valuable tool for further, more detailed, analyses of the muscle wasting occurring in patients kept on a mechanical ventilator.
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| 6. |
- Wettergren, Yvonne, 1957, et al.
(författare)
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p16(INK4a) Gene Promoter Hypermethylation in Mucosa as a Prognostic Factor for Patients with Colorectal Cancer.
- 2008
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Ingår i: Molecular medicine. - 1076-1551 .- 1528-3658. ; 14:7-8, s. 412-421
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Tidskriftsartikel (refereegranskat)abstract
- Low gene expression of folylpolyglutamate synthase (FPGS) in colorectal mucosa correlates with low folate levels and poor survival of colorectal cancer (CRC) patients. Because gene-specific hypermethylation is affected by the folate level, the hypermethylation status in mucosa may also be linked to clinical outcome of CRC patients. The tumor suppressor gene p16INK4a (p16) regulates the cell cycle and angiogenic switch. In human neoplastic tissues, the main mechanism of p16 inactivation is promoter methylation. The aim of the study was to determine whether hypermethylation of the p16 promoter could be detected in mucosa of CRC patients (n = 181) and to analyze if hypermethylation was related to survival. The relation between p16 hypermethylation and expression of FPGS and two other folate-associated genes, reduced folate carrier 1 (RFC-1), and thymidylate synthase (TS), was analyzed (n = 63). The results showed that p16 was hypermethylated in 65 (36%) of the mucosa samples and that hypermethylation was age-related (P = 0.029). After adjustment for known risk factors, Cox regression analysis showed that Dukes' A-C patients with p16 hypermethylation in mucosa had an increased risk of cancer-related death (hazard ratio = 2.9, P= 0.007) and shorter disease-free survival (hazard ratio = 2.5, P = 0.015) compared with patients with no p16 hypermethylation. RFC-1 and FPGS gene expression levels were significantly correlated in patients lacking p16 hypermethylation in mucosa (P = 0.0003), but not at all correlated in patients having hypermethylation in mucosa (P = 1.0). In conclusion, p16 hypermethylation in mucosa of CRC patients was identified as an independent prognostic parameter for cancer-specific survival as well as an independent predictor of DFS. The results suggest that there might be a connection between folate-associated gene expression and p16 methylation status.
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| 9. |
- Lampinen Salomonsson, Matilda, et al.
(författare)
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In vitro formation of phase I and II metabolites of propranolol and determination of their structures using chemical derivatization and liquid chromatography tandem mass spectrometry
- 2009
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Ingår i: Journal of Mass Spectrometry. - : Wiley. - 1076-5174 .- 1096-9888. ; 44:5, s. 742-754
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Tidskriftsartikel (refereegranskat)abstract
- Derivatization with 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC) has been successfully used as a tool to differentiate between aromatic and aliphatic O-glucuronides of hydroxypropranolol. The analyses were performed with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) with both a triple quadrupole and an ion trap instrument. Hydroxylated forms of propranolol can be glucuronidated in aliphatic as well as aromatic positions. These isoforms are not distinguishable by tandem MS alone, as they both initially lose 176 Da, i.e. monodehydrated glucuronic acid, giving back the aglycone. Two in vitro systems were set up for the production of propranolol metabolites. The obtained isomers of 4'-hydroxypropranolol glucuronide were determined to correspond to one aliphatic and one aromatic form, using chemical derivatization with DMISC and LC-MSn. DMISC was shown to react with the secondary amine in the case where the naphtol was occupied by the glucuronyl moiety, resulting in a different fragmentation pattern compared with that of the aliphatic glucuronide, where the naphtol group was accessible to derivatization.
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