| 1. |
- Arner, P., et al.
(författare)
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Adipose lipid turnover and long-term changes in body weight
- 2019
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Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 25:9, s. 1385-1389
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Tidskriftsartikel (refereegranskat)abstract
- The worldwide obesity epidemic(1) makes it important to understand how lipid turnover (the capacity to store and remove lipids) regulates adipose tissue mass. Cross-sectional studies have shown that excess body fat is associated with decreased adipose lipid removal rates(2,3). Whether lipid turnover is constant over the life span or changes during long-term weight increase or loss is unknown. We determined the turnover of fat cell lipids in adults followed for up to 16 years, by measuring the incorporation of nuclear bomb test-derived C-14 in adipose tissue triglycerides. Lipid removal rate decreases during aging, with a failure to reciprocally adjust the rate of lipid uptake resulting in weight gain. Substantial weight loss is not driven by changes in lipid removal but by the rate of lipid uptake in adipose tissue. Furthermore, individuals with a low baseline lipid removal rate are more likely to remain weight-stable after weight loss. Therefore, lipid turnover adaptation might be important for maintaining pronounced weight loss. Together these findings identify adipose lipid turnover as an important factor for the long-term development of overweight/obesity and weight loss maintenance in humans.
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| 2. |
- Arner, Peter, et al.
(författare)
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Dynamics of human adipose lipid turnover in health and metabolic disease
- 2011
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 478:7367, s. 110-113
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Tidskriftsartikel (refereegranskat)abstract
- Adipose tissue mass is determined by the storage and removal of triglycerides in adipocytes(1). Little is known, however, about adipose lipid turnover in humans in health and pathology. To study this in vivo, here we determined lipid age by measuring (14)C derived from above ground nuclear bomb tests in adipocyte lipids. We report that during the average ten-year lifespan of human adipocytes, triglycerides are renewed six times. Lipid age is independent of adipocyte size, is very stable across a wide range of adult ages and does not differ between genders. Adipocyte lipid turnover, however, is strongly related to conditions with disturbed lipid metabolism. In obesity, triglyceride removal rate (lipolysis followed by oxidation) is decreased and the amount of triglycerides stored each year is increased. In contrast, both lipid removal and storage rates are decreased in non-obese patients diagnosed with the most common hereditary form of dyslipidaemia, familial combined hyperlipidaemia. Lipid removal rate is positively correlated with the capacity of adipocytes to break down triglycerides, as assessed through lipolysis, and is inversely related to insulin resistance. Our data support a mechanism in which adipocyte lipid storage and removal have different roles in health and pathology. High storage but low triglyceride removal promotes fat tissue accumulation and obesity. Reduction of both triglyceride storage and removal decreases lipid shunting through adipose tissue and thus promotes dyslipidaemia. We identify adipocyte lipid turnover as a novel target for prevention and treatment of metabolic disease.
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| 3. |
- Bergmann, Olaf, et al.
(författare)
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Dynamics of Cell Generation and Turnover in the Human Heart.
- 2015
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Ingår i: Cell. - : Elsevier BV. - 1097-4172 .- 0092-8674. ; 161:7, s. 1566-1575
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of cell generation to physiological heart growth and maintenance in humans has been difficult to establish and has remained controversial. We report that the full complement of cardiomyocytes is established perinataly and remains stable over the human lifespan, whereas the numbers of both endothelial and mesenchymal cells increase substantially from birth to early adulthood. Analysis of the integration of nuclear bomb test-derived (14)C revealed a high turnover rate of endothelial cells throughout life (>15% per year) and more limited renewal of mesenchymal cells (<4% per year in adulthood). Cardiomyocyte exchange is highest in early childhood and decreases gradually throughout life to <1% per year in adulthood, with similar turnover rates in the major subdivisions of the myocardium. We provide an integrated model of cell generation and turnover in the human heart. VIDEO ABSTRACT.
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| 4. |
- Eilers, Gerriet, et al.
(författare)
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The Radiocarbon Intracavity Optogalvanic Spectroscopy Setup at Uppsala
- 2013
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Ingår i: Radiocarbon. - : Cambridge University Press (CUP). - 0033-8222 .- 1945-5755. ; 55:3-4, s. 237-250
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Tidskriftsartikel (refereegranskat)abstract
- Accelerator mass spectrometry (AMS) is by far the predominant technology deployed for radiocarbon tracer studies. Applications are widespread from archaeology to biological, environmental, and pharmaceutical sciences. In spite of its excellent performance, AMS is expensive and complicated to operate. Consequently, alternative detection techniques for 14C are of great interest, with the vision of a compact, user-friendly, and inexpensive analytical method. Here, we report on the use of intracavity optogalvanic spectroscopy (ICOGS) for measurements of the 14C/12C ratio. This new detection technique was developed by Murnick et al. (2008). In the infrared (IR) region, CO2 molecules have strong absorption coefficients. The IR-absorption lines are narrow in line width and shifted for different carbon isotopes. These properties can potentially be exploited to detect 14CO2, 13CO2, or 12CO2 molecules unambiguously. In ICOGS, the sample is in the form of CO2 gas, eliminating the graphitization step that h is required in most AMS labs. The status of the ICOGS setup in Uppsala is presented. The system is operational but not yet fully developed. Data are presented for initial results that illustrate the dependence of the optogalvanic signal on various parameters, such as background and plasma-induced changes in the sample gas composition.
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| 5. |
- Ernst, Aurélie, et al.
(författare)
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Neurogenesis in the Striatum of the Adult Human Brain
- 2014
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Ingår i: Cell. - Cambridge, MA 02139, USA : Elsevier. - 0092-8674 .- 1097-4172. ; 156:5, s. 1072-1083
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Tidskriftsartikel (refereegranskat)abstract
- Neurons are added throughout life in the hippocampus and olfactory bulb in most mammals, although humans represent an exception without detectable olfactory bulb neurogenesis. Nevertheless, neuroblasts are generated in the lateral ventricle wall in humans, the neurogenic niche for olfactory bulb neurons in other mammals. We show that, in humans, new neurons integrate adjacent to this neurogenic niche, in the striatum. The neuronal turnover in the striatum appears restricted to interneurons and we show that postnatally generated striatal neurons are preferentially depleted in Huntington’s disease. This demonstrates a unique pattern of neurogenesis in the adult human brain.
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| 6. |
- Forsgård, Niklas, et al.
(författare)
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Accelerator mass spectrometry in the attomolar concentration range for C-14-labeled biologically active compounds in complex matrixes
- 2010
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 25:1, s. 74-78
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Tidskriftsartikel (refereegranskat)abstract
- Accelerator mass spectrometry (AMS) is an ultra-sensitive analytical method suitable for detection of sub-nanomolar concentrations of labeled biological substances such as pharmaceutical drugs in body fluids. A limiting factor in extending the concentration measurements to the sub-picomolar range is the natural C-14 content in living tissues. This can be circumvented by separating the labeled drug from the tissue matrix with, for example, liquid chromatography. The analysis of drugs and their metabolites or endogenous compounds in biological fluids by liquid chromatography is usually complicated and the sample preparation step remains the most serious problem both with regard to losses and degradation of the analyte, and also automation of the analysis. In this article a method for detection and quantification of extremely low concentrations of C-14-labeled biomolecules in biological fluids by AMS is described. The use of a column switched chromatographic system incorporating a restricted-access media (RAM) column allowed the direct injection of untreated human plasma samples, which reduces the total time of analysis and makes automation of the sample preparation step possible. As the separated total drug amount is in the attogram to femtogram region, it is not possible to use a standard AMS sample preparation method, where mg sizes are required. We have utilized a sensitive carbon carrier method where a C-14-deficient compound is added to the HPLC fractions and the composite sample is prepared and analysed by AMS. The method shows remarkable sensitivity, low background values and good linearity, allowing the detection and quantification of a pharmaceutical drug in human plasma in the low femtomolar and down to the attomolar concentration range.
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| 7. |
- Heinke, Paula, et al.
(författare)
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Diploid hepatocytes drive physiological liver renewal in adult humans
- 2022
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Ingår i: CELL SYSTEMS. - : Elsevier. - 2405-4712 .- 2405-4720. ; 13:6, s. 499-
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Tidskriftsartikel (refereegranskat)abstract
- Physiological liver cell replacement is central to maintaining the organ's high metabolic activity, although its characteristics are difficult to study in humans. Using retrospective radiocarbon (C-14) birth dating of cells, we report that human hepatocytes show continuous and lifelong turnover, allowing the liver to remain a young organ (average age <3 years). Hepatocyte renewal is highly dependent on the ploidy level. Diploid hepatocytes show more than 7-fold higher annual birth rates than polyploid hepatocytes. These observations support the view that physiological liver cell renewal in humans is mainly dependent on diploid hepatocytes, whereas polyploid cells are compromised in their ability to divide. Moreover, cellular transitions between diploid and polyploid hepatocytes are limited under homeostatic conditions. With these findings, we present an integrated model of homeostatic liver cell generation in humans that provides fundamental insights into liver cell turnover dynamics.
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| 8. |
- Huttner, Hagen B., et al.
(författare)
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Meningioma growth dynamics assessed by radiocarbon retrospective birth dating
- 2018
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Ingår i: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 27, s. 176-181
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Tidskriftsartikel (refereegranskat)abstract
- It is not known how long it takes from the initial neoplastic transformation of a cell to the detection of a tumor, which would be valuable for understanding tumor growth dynamics. Meningiomas show a broad histological, genetic and clinical spectrum, are usually benign and considered slowly growing. There is an intense debate regarding their age and growth pattern and when meningiomas should be resected. We have assessed the age and growth dynamics of 14 patients with meningiomas (WHO grade I: n = 6 with meningothelial and n = 6 with fibrous subtype, as well as n = 2 atypical WHO grade II meningiomas) by combining retrospective birth-dating of cells by analyzing incorporation of nuclear-bomb-test-derived 14C, analysis of cell proliferation, cell density, MRI imaging and mathematical modeling. We provide an integrated model of the growth dynamics of benign meningiomas. The mean age of WHO grade I meningiomas was 22.1 ± 6.5 years, whereas atypical WHO grade II meningiomas originated 1.5 ± 0.1 years prior to surgery (p < 0.01). We conclude that WHO grade I meningiomas are very slowly growing brain tumors, which are resected in average two decades after time of origination.
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| 9. |
- Huttner, Hagen B, et al.
(författare)
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The age and genomic integrity of neurons after cortical stroke in humans
- 2014
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Ingår i: Nature Neuroscience. - : Springer Science and Business Media LLC. - 1097-6256 .- 1546-1726. ; 17:6, s. 801-803
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Tidskriftsartikel (refereegranskat)abstract
- It has been unclear whether ischemic stroke induces neurogenesis or neuronal DNA rearrangements in the human neocortex. Using immunohistochemistry; transcriptome, genome and ploidy analyses; and determination of nuclear bomb test-derived (14)C concentration in neuronal DNA, we found neither to be the case. A large proportion of cortical neurons displayed DNA fragmentation and DNA repair a short time after stroke, whereas neurons at chronic stages after stroke showed DNA integrity, demonstrating the relevance of an intact genome for survival.
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| 10. |
- Hägg, Sara, 1977-, et al.
(författare)
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Carbon-14 Dating to Determine Carotid Plaque Age : Carbon-14 Dating of Carotid Plaques
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Rationale: The exact nature of atherosclerotic plaque development and the molecular mechanisms that lead to clinical manifestations of carotid stenosis are unclear. After nuclear bomb tests in the 1950s, atmospheric 14C concentrations rapidly increased. Since then, the concentrations have been declining, and the curve of declination can be used to date biological samples synthesized during the last five to six decades. Objective: To investigate plaque age as a novel characteristic of atherosclerotic plaques in patients with carotid stenosis. Methods and Results: Carotid plaques from 29 well-characterized endarterectomy patients with symptomatic carotid stenosis were analyzed by accelerator mass spectrometry, and global gene expression of 25 plaque samples was profiled with HG-U133 Plus 2.0 arrays. The average plaque age was 9.3 years, and inter- and intrasample standard variations were low (1–3.5 years); thus, most of the plaques were generated 5–15 years before surgery. Plaque age was not associated with patient age or plaque size, determined by intima-media thickness, but was inversely related to plasma insulin levels (P=0.0014). A cluster of functionally related genes enriched with genes involved in immune responses was activated in plaques with low plaque age, as were oxidative phosphorylation genes. Conclusion: Patients with mild insulin resistance have increased immune and inflammatory gene activity in their carotid plaques causing them to become instable, rapidly progressing into clinical manifestations at a relatively young age. These results show that plaque age, determined by 14C dating, is a novel and important characteristic of atherosclerotic plaques that will improve our understanding of the clinical significance and molecular underpinnings of atherosclerosis.
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