| 1. |
- Pirinen, E., et al.
(författare)
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Enhanced polyamine catabolism alters homeostatic control of white adipose tissue mass, energy expenditure, and glucose metabolism
- 2007
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Ingår i: Mol Cell Biol. - 0270-7306. ; 27:13, s. 4953-67
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Tidskriftsartikel (refereegranskat)abstract
- Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 alpha) is an attractive candidate gene for type 2 diabetes, as genes of the oxidative phosphorylation (OXPHOS) pathway are coordinatively downregulated by reduced expression of PGC-1 alpha in skeletal muscle and adipose tissue of patients with type 2 diabetes. Here we demonstrate that transgenic mice with activated polyamine catabolism due to overexpression of spermidine/spermine N(1)-acetyltransferase (SSAT) had reduced white adipose tissue (WAT) mass, high basal metabolic rate, improved glucose tolerance, high insulin sensitivity, and enhanced expression of the OXPHOS genes, coordinated by increased levels of PGC-1 alpha and 5'-AMP-activated protein kinase (AMPK) in WAT. As accelerated polyamine flux caused by SSAT overexpression depleted the ATP pool in adipocytes of SSAT mice and N(1),N(11)-diethylnorspermine-treated wild-type fetal fibroblasts, we propose that low ATP levels lead to the induction of AMPK, which in turn activates PGC-1 alpha in WAT of SSAT mice. Our hypothesis is supported by the finding that the phenotype of SSAT mice was reversed when the accelerated polyamine flux was reduced by the inhibition of polyamine biosynthesis in WAT. The involvement of polyamine catabolism in the regulation of energy and glucose metabolism may offer a novel target for drug development for obesity and type 2 diabetes.
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| 2. |
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| 3. |
- Parkkinen, L, et al.
(författare)
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Abundant glial alpha-synuclein pathology in a case without overt clinical symptoms.
- 2007
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Ingår i: Clinical Neuropathology. - 0722-5091. ; 26:6, s. 276-83
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Tidskriftsartikel (refereegranskat)abstract
- Screening of 1,800 brains with alpha-synuclein (alphaS) immunohistochemistry revealed five cases with abundant glial cytoplasmic inclusions (GCIs) within the white matter of the brainstem. Surprisingly, retrospective clinical assessment showed that one of these subjects did not fulfil the currently recommended clinical consensus criteria for the multiple system atrophy (MSA). One of the hallmark lesions of MSA, alphaS-positive GCIs, were widespread and abundant in this atypical case that nonetheless lacked any significant neuronal loss. If the patient had met the clinical criteria for MSA, the neuropathological phenotype would have undeniably confirmed the clinically suggested diagnosis. However, lacking overt clinical signs of MSA, the neuropathological phenotype in this subject is prone to be variably denoted or overlooked. We would therefore like to advise neuropathologists to acknowledge these cases with "occult" alpha-synucleinopathy and to inform the clinicians of such a finding. Whether these cases represent a preclinical stage of MSA or simply a biological coincidence, is yet unknown. The observation of abundant GCIs in an asymptomatic subject is, however, important, because even if these cases are rare in number, their occurrence challenge the current presumption, whereby simply the number of alphaS-positive GCIs mediates the neuronal dysfunction responsible for the clinical symptoms of MSA.
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