| 1. |
- Sarmiento Pico, Luis, et al.
(författare)
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Elucidating the nature of the proton radioactivity and branching ratio on the first proton emitter discovered 53mCo
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The observation of a weak proton-emission branch in the decay of the 3174keV 53mCo isomeric state marked the discovery of proton radioactivity in atomic nuclei in 1970. Here we show, based on the partial half-lives and the decay energies of the possible proton-emission branches, that the exceptionally high angular momentum barriers, lp = 9 and lp = 7, play a key role in hindering the proton radioactivity from 53mCo, making them very challenging to observe and calculate. Indeed, experiments had to wait decades for significant advances in accelerator facilities and multi-faceted state-of-the-art decay stations to gain full access to all observables. Combining data taken with the TASISpec decay station at the Accelerator Laboratory of the University of Jyväskylä, Finland, and the ACTAR TPC device on LISE3 at GANIL, France, we measured their branching ratios as bp1 = 1.3(1)% and bp2 = 0.025(4)%. These results were compared to cutting-edge shell-model and barrier penetration calculations. This description reproduces the order of magnitude of the branching ratios and partial half-lives, despite their very small spectroscopic factors.
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| 2. |
- Billing, Matilda, et al.
(författare)
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Signaling via Smad2 and Smad3 is dispensable for adult murine hematopoietic stem cell function in vivo
- 2017
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Ingår i: Experimental Hematology. - : Elsevier BV. - 0301-472X.
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor-β (TGFβ) is a member of a large family of polypeptide growth factors. TGFβ signals mainly through the intracellular proteins Smad2 and Smad3, which are highly similar in amino acid sequence identity. A number of studies have shown that these proteins, dependent on context, have distinct roles in the TGFβ signaling pathway. TGFβ is one of the most potent inhibitors of hematopoietic stem and progenitor cell proliferation in vitro, but its role in hematopoiesis in vivo is still being determined. To circumvent possible redundancies at the receptor level and to address specifically the role of the Smad circuitry downstream of TGFβ and activin in hematopoiesis, we studied the effect of genetically deleting both Smad2 and Smad3 in adult murine hematopoietic cells. Indeed, TGFβ signaling is impaired in vitro in primitive bone marrow (BM) cells of Smad2 and Smad3 single knockout models. However, blood parameters appear normal under steady state and in the transplantation setting. Interestingly, upon deletion of both Smad2 and Smad3 in vivo, mice quickly develop a lethal inflammatory disease, suggesting that activin/TGFβ signaling is crucial for immune cell homeostasis in the adult context. Furthermore, concurrent deletion of Smad2 and Smad3 in BM cells in immune-deficient nude mice did not result in any significant alterations of the hematopoietic system. Our findings suggest that Smad2 and Smad3 function to mediate crucial aspects of the immunoregulatory properties of TGFβ, but are dispensable for any effect that TGFβ has on primitive hematopoietic cells in vivo.
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| 3. |
- Blank Savukinas, Ulrika, et al.
(författare)
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Angptl4 maintains in vivo repopulation capacity of CD34(+) human cord blood cells.
- 2012
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Ingår i: European Journal of Haematology. - : Wiley. - 1600-0609 .- 0902-4441. ; 89:3, s. 198-205
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Methods to expand hematopoietic stem cells (HSCs) ex vivo encompass an attractive approach that would substantially broaden the clinical applicability of HSCs derived from cord blood. Recently, members of the Angiopoietin-like (Angptl) family of growth factors were shown to expand both murine and human HSCs. Specifically, Angptl5 has been implicated in the expansion of human NOD-SCID-repopulating cells (SRCs) ex vivo. Here, we sought to evaluate the potential of additional Angptls to expand human SRCs from cord blood. Additionally, the purpose of this study was to evaluate the reproducibility of Angptl-mediated expansion of SRCs across independent experiments. METHODS: Human CD34(+) cells from cord blood were cultured in vitro for eleven or eight days in the presence or absence of Angptls. The reconstitution capacity of expanded cells was subsequently measured in vivo by transplantation into NOD-SCID or NSG mice, and compared to that of uncultured cells. RESULTS: We report here that Angptl4 functions to maintain SRC-activity of CD34(+) CB-derived cells ex vivo as assayed in NOD-SCID and NSG mice. However, all Angptls tested, including Angptl1, 4, and 5, were associated with variation between experiments. CONCLUSION: Our findings indicate that Angptl4 and Angptl5 can lead to increased engraftment capacity of SRCs, but more frequently these factors are associated with maintenance of SRC-activity during ex vivo culture. Thus, Angptl-mediated expansion of SRCs ex vivo is associated with more inter-experimental variation than previously thought. We conclude that Angptls would be useful in instances where there is a need to maintain HSCs ex vivo, such as during transduction for gene therapy applications.
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| 4. |
- Blank Savukinas, Ulrika
(författare)
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Regulation of hematopoiesis by the Smad signaling pathway
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hematopoietic stem cells (HSCs) reside in the bone marrow (BM) of adult individuals and are ultimately responsible for the continuous production of blood cells throughout life. The regulation of HSCs in vivo is tightly regulated by both intrinsic and extrinsic factors. The Smad-signaling pathway is an evolutionary conserved signaling circuitry with critical functions during embryogenesis and throughout adult life, regulating diverse biological processes. The transforming growth factor-? (TGF-?) superfamily of ligands transduce their signals intracellularly through the Smad pathway. A large number of studies, the majority of which have been carried out in vitro, have cataloged TGF-? as a potent negative regulator of HSC proliferation. However, due to embryonic lethality of knockout mice, in vivo investigations of the role of TGF-? and the downstream Smad pathway in the context of adult hematopoiesis have been hampered. To address this, we made use of the Cre/loxP system for inducible gene deletion of two different components of the TGF-? signaling pathway, the type I TGF-? receptor and Smad4 respectively. In addition, retroviral mediated gene transfer to HSCs was used as a tool to block the entire Smad-signaling pathway, by overexpression of the inhibitory Smad7. Induced disruption of the type I TGF-? receptor in adult mice resulted in an inflammatory disorder with a lethal outcome 8-10 weeks post induction. However, all hematopoietic parameters were normal under steady state conditions as well as the regenerative- and self-renewal capacity of mutant HSCs as assessed by transplantation. Smad4 null HSCs exhibited impaired repopulative capacity in a competitive repopulation assay, a behavior that was exacerbated upon secondary transplantation. Overexpression of Smad7 in HSCs resulted in increased regenerative capacity upon secondary transplantation, with a normal lineage distribution. Taken together, our data suggests that the Smad pathway is a critical regulator of HSC self-renewal in vivo.
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| 5. |
- Blank Savukinas, Ulrika, et al.
(författare)
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Signaling pathways governing stem cell fate.
- 2008
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 111:2, s. 492-503
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Forskningsöversikt (refereegranskat)abstract
- Hematopoietic stem cells (HSCs) are historically the most thoroughly characterized type of adult stem cell, and the hematopoietic system has served as a principal model structure of stem-cell biology for several decades. However, paradoxically, although HSCs can be defined by function and even purified to near-homogeneity, the intricate molecular machinery and the signaling mechanisms regulating fate events, such as self-renewal and differentiation, have remained elusive. Recently, several developmentally conserved signaling pathways have emerged as important control devices of HSC fate, including Notch, Wingless-type (Wnt), Sonic hedgehog (Shh), and Smad pathways. HSCs reside in a complex environment in the bone marrow, providing a niche that optimally balances signals that control self-renewal and differentiation. These signaling circuits provide a valuable structure for our understanding of how HSC regulation occurs, concomitantly with providing information of how the bone marrow microenvironment couples and integrates extrinsic with intrinsic HSC fate determinants. It is the focus of this review to highlight some of the most recent developments concerning signaling pathways governing HSC fate.
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| 6. |
- Blank Savukinas, Ulrika, et al.
(författare)
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Smad7 promotes self-renewal of hematopoietic stem cells in vivo.
- 2006
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 108:13, s. 4246-4254
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Tidskriftsartikel (refereegranskat)abstract
- The Smad-signaling pathway downstream of the transforming growth factor–beta superfamily of ligands is an evolutionarily conserved signaling circuitry with critical functions in a wide variety of biologic processes. To investigate the role of this pathway in the regulation of hematopoietic stem cells (HSCs), we have blocked Smad signaling by retroviral gene transfer of the inhibitory Smad7 to murine HSCs. We report here that the self-renewal capacity of HSCs is promoted in vivo upon blocking of the entire Smad pathway, as shown by both primary and secondary bone marrow (BM) transplantations. Importantly, HSCs overexpressing Smad7 have an unperturbed differentiation capacity as evidenced by normal contribution to both lymphoid and myeloid cell lineages, suggesting that the Smad pathway regulates self-renewal independently of differentiation. Moreover, phosphorylation of Smads was inhibited in response to ligand stimulation in BM cells, thus verifying impairment of the Smad-signaling cascade in Smad7-overexpressing cells. Taken together, these data reveal an important and previously unappreciated role for the Smad-signaling pathway in the regulation of self-renewal of HSCs in vivo.
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| 7. |
- Blank Savukinas, Ulrika, et al.
(författare)
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TGF-β signaling in the control of hematopoietic stem cells.
- 2015
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 125:23, s. 3542-3550
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Tidskriftsartikel (refereegranskat)abstract
- Blood is a tissue with high cellular turnover, and its production is a tightly orchestrated process that requires constant replenishment. All mature blood cells are generated from hematopoietic stem cells (HSCs), which are the self-renewing units that sustain life-long hematopoiesis. HSC behavior, such as self-renewal and quiescence, are regulated by a wide array of factors, including external signaling cues present in the bone marrow. The Transforming Growth Factor-β (TGF-β) family of cytokines constitutes a multifunctional signaling circuitry, which regulates pivotal functions related to cell fate and behavior in virtually all tissues of the body. In the hematopoietic system, TGF-β signaling controls a wide spectrum of biological processes, from homeostasis of the immune system to quiescence and self-renewal of HSCs. Here, we review key features and emerging concepts pertaining to TGF-β and downstream signaling pathways in normal HSC biology, featuring aspects of aging, hematological disease, and how this circuitry may be exploited for clinical purposes in the future.
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| 8. |
- Blank Savukinas, Ulrika, et al.
(författare)
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The Bystander Effect : Mesenchymal Stem Cell-Mediated Lung Repair
- 2016
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 34:6, s. 1437-1444
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Forskningsöversikt (refereegranskat)abstract
- Mesenchymal stem or stromal cells (MSCs), a heterogeneous subset of adult stem/progenitor cells, have surfaced as potential therapeutic units with significant clinical benefit for a wide spectrum of disease conditions, including those affecting the lung. Although MSCs carry both self-renewal and multilineage differentiation abilities, current dogma holds that MSCs mainly contribute to tissue regeneration and repair by modulating the host tissue via secreted cues. Thus, the therapeutic benefit of MSCs is thought to derive from so called bystander effects. The regenerative mechanisms employed by MSCs in the lung include modulation of the immune system as well as promotion of epithelial and endothelial repair. Apart from secreted factors, a number of recent findings suggest that MSCs engage in mitochondrial transfer and shedding of membrane vesicles as a means to enhance tissue repair following injury. Furthermore, it is becoming increasingly clear that MSCs are an integral component of epithelial lung stem cell niches. As such, MSCs play an important role in coupling information from the environment to stem and progenitor populations, such that homeostasis can be ensured even in the face of injury. It is the aim of this review to outline the major mechanisms by which MSCs contribute to lung regeneration, synthesizing recent preclinical findings with data from clinical trials and potential for future therapy
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| 9. |
- Blank Savukinas, Ulrika, et al.
(författare)
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The role of Smad signaling in hematopoiesis and translational hematology.
- 2011
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 25, s. 1379-1388
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Tidskriftsartikel (refereegranskat)abstract
- Hematopoietic stem cells (HSCs) reside in the bone marrow (BM) of adult individuals and function to produce and regenerate the entire blood and immune system over the course of an individual's lifetime. Historically, HSCs are among the most thoroughly characterized tissue-specific stem cells. Despite this, the regulation of fate options, such as self-renewal and differentiation, has remained elusive, partly because of the expansive plethora of factors and signaling cues that govern HSC behavior in vivo. In the BM, HSCs are housed in specialized niches that dovetail the behavior of HSCs with the need of the organism. The Smad-signaling pathway, which operates downstream of the transforming growth factor-β (TGF-β) superfamily of ligands, regulates a diverse set of biological processes, including proliferation, differentiation and apoptosis, in many different organ systems. Much of the function of Smad signaling in hematopoiesis has remained nebulous due to early embryonic lethality of most knockout mouse models. However, recently new data have been uncovered, suggesting that the Smad-signaling circuitry is intimately linked to HSC regulation. In this review, we bring the Smad-signaling pathway into focus, chronicling key concepts and recent advances with respect to TGF-β-superfamily signaling in normal and leukemic hematopoiesis.Leukemia advance online publication, 13 May 2011; doi:10.1038/leu.2011.95.
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| 10. |
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