13 results on '"Vrinda Sreekumar"'
Search Results
2. Exogenous Delivery of Link N mRNA into Chondrocytes and MSCs—The Potential Role in Increasing Anabolic Response
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Gauri Tendulkar, Sabrina Ehnert, Vrinda Sreekumar, Tao Chen, Hans-Peter Kaps, Sonia Golombek, Hans-Peter Wendel, Andreas K. Nüssler, and Meltem Avci-Adali
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Synthetic mRNA ,Link N peptide ,mRNA delivery ,musculoskeletal disorders ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Musculoskeletal disorders, such as osteoarthritis and intervertebral disc degeneration are causes of morbidity, which concomitantly burdens the health and social care systems worldwide, with massive costs. Link N peptide has recently been described as a novel anabolic stimulator for intervertebral disc repair. In this study, we analyzed the influence on anabolic response, by delivering synthetic Link N encoding mRNA into primary human chondrocytes and mesenchymal stromal cells (SCP1 cells). Furthermore, both cell types were seeded on knitted titanium scaffolds, and the influence of Link N peptide mRNA for possible tissue engineering applications was investigated. Synthetic modified Link N mRNA was efficiently delivered into both cell types and cell transfection resulted in an enhanced expression of aggrecan, Sox 9, and type II collagen with a decreased expression of type X collagen. Interestingly, despite increased expression of BMP2 and BMP7, BMP signaling was repressed and TGFβ signaling was boosted by Link N transfection in mesenchymal stromal cells, suggesting possible regulatory mechanisms. Thus, the exogenous delivery of Link N peptide mRNA into cells augmented an anabolic response and thereby increased extracellular matrix synthesis. Considering these findings, we suppose that the cultivation of cells on knitted titanium scaffolds and the exogenous delivery of Link N peptide mRNA into cells could mechanically support the stability of tissue-engineered constructs and improve the synthesis of extracellular matrix by seeded cells. This method can provide a potent strategy for articular cartilage and intervertebral disc regeneration.
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- 2019
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3. Correction: Spastic Paraplegia Mutation N256S in the Neuronal Microtubule Motor KIF5A Disrupts Axonal Transport in a HSP Model.
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Petra Füger, Vrinda Sreekumar, Rebecca Schüle, Jeannine V. Kern, Doychin T. Stanchev, Carola D. Schneider, Kathrin N. Karle, Katharina J. Daub, Vera K. Siegert, Matthias Flötenmeyer, Heinz Schwarz, Ludger Schöls, and Tobias M. Rasse
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Genetics ,QH426-470 - Published
- 2013
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4. Knockdown of Hsc70-5/mortalin induces loss of synaptic mitochondria in a Drosophila Parkinson's disease model.
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Jun-Yi Zhu, Natalia Vereshchagina, Vrinda Sreekumar, Lena F Burbulla, Ana C Costa, Katharina J Daub, Dirk Woitalla, L Miguel Martins, Rejko Krüger, and Tobias M Rasse
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Medicine ,Science - Abstract
Mortalin is an essential component of the molecular machinery that imports nuclear-encoded proteins into mitochondria, assists in their folding, and protects against damage upon accumulation of dysfunctional, unfolded proteins in aging mitochondria. Mortalin dysfunction associated with Parkinson's disease (PD) increases the vulnerability of cultured cells to proteolytic stress and leads to changes in mitochondrial function and morphology. To date, Drosophila melanogaster has been successfully used to investigate pathogenesis following the loss of several other PD-associated genes. We generated the first loss-of-Hsc70-5/mortalin-function Drosophila model. The reduction of Mortalin expression recapitulates some of the defects observed in the existing Drosophila PD-models, which include reduced ATP levels, abnormal wing posture, shortened life span, and reduced spontaneous locomotor and climbing ability. Dopaminergic neurons seem to be more sensitive to the loss of mortalin than other neuronal sub-types and non-neuronal tissues. The loss of synaptic mitochondria is an early pathological change that might cause later degenerative events. It precedes both behavioral abnormalities and structural changes at the neuromuscular junction (NMJ) of mortalin-knockdown larvae that exhibit increased mitochondrial fragmentation. Autophagy is concomitantly up-regulated, suggesting that mitochondria are degraded via mitophagy. Ex vivo data from human fibroblasts identifies increased mitophagy as an early pathological change that precedes apoptosis. Given the specificity of the observed defects, we are confident that the loss-of-mortalin model presented in this study will be useful for further dissection of the complex network of pathways that underlie the development of mitochondrial parkinsonism.
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- 2013
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5. Spastic paraplegia mutation N256S in the neuronal microtubule motor KIF5A disrupts axonal transport in a Drosophila HSP model.
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Petra Füger, Vrinda Sreekumar, Rebecca Schüle, Jeannine V Kern, Doychin T Stanchev, Carola D Schneider, Kathrin N Karle, Katharina J Daub, Vera K Siegert, Matthias Flötenmeyer, Heinz Schwarz, Ludger Schöls, and Tobias M Rasse
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Genetics ,QH426-470 - Abstract
Hereditary spastic paraplegias (HSPs) comprise a group of genetically heterogeneous neurodegenerative disorders characterized by spastic weakness of the lower extremities. We have generated a Drosophila model for HSP type 10 (SPG10), caused by mutations in KIF5A. KIF5A encodes the heavy chain of kinesin-1, a neuronal microtubule motor. Our results imply that SPG10 is not caused by haploinsufficiency but by the loss of endogenous kinesin-1 function due to a selective dominant-negative action of mutant KIF5A on kinesin-1 complexes. We have not found any evidence for an additional, more generalized toxicity of mutant Kinesin heavy chain (Khc) or the affected kinesin-1 complexes. Ectopic expression of Drosophila Khc carrying a human SPG10-associated mutation (N256S) is sufficient to disturb axonal transport and to induce motoneuron disease in Drosophila. Neurofilaments, which have been recently implicated in SPG10 disease manifestation, are absent in arthropods. Impairments in the transport of kinesin-1 cargos different from neurofilaments are thus sufficient to cause HSP-like pathological changes such as axonal swellings, altered structure and function of synapses, behavioral deficits, and increased mortality.
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- 2012
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6. Ciliary exclusion of Polycystin-2 promotes kidney cystogenesis in an autosomal dominant polycystic kidney disease model
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Vrinda Sreekumar, Rebecca V Walker, Martin M. Knight, Jennifer L. Keynton, Christopher T. Esapa, Debbie Williams, Daniel T. Grimes, Dongsheng Wu, and Dominic P. Norris
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0301 basic medicine ,Male ,Glycosylation ,Mutant ,General Physics and Astronomy ,02 engineering and technology ,TRPP ,Kidney ,urologic and male genital diseases ,lcsh:Science ,education.field_of_study ,Multidisciplinary ,Cilium ,Medical genetics ,021001 nanoscience & nanotechnology ,Polycystic Kidney, Autosomal Dominant ,female genital diseases and pregnancy complications ,Cell biology ,Polycystin 2 ,medicine.anatomical_structure ,Female ,0210 nano-technology ,endocrine system ,TRPP Cation Channels ,Science ,Autosomal dominant polycystic kidney disease ,Biology ,Development ,General Biochemistry, Genetics and Molecular Biology ,Article ,03 medical and health sciences ,medicine ,Animals ,Humans ,Cilia ,RNA, Messenger ,education ,Ciliogenesis ,Disease model ,urogenital system ,General Chemistry ,Fibroblasts ,medicine.disease ,Embryo, Mammalian ,Embryonic stem cell ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,Mutation ,lcsh:Q ,Ciliary base - Abstract
The human PKD2 locus encodes Polycystin-2 (PC2), a TRPP channel that localises to several distinct cellular compartments, including the cilium. PKD2 mutations cause Autosomal Dominant Polycystic Kidney Disease (ADPKD) and affect many cellular pathways. Data underlining the importance of ciliary PC2 localisation in preventing PKD are limited because PC2 function is ablated throughout the cell in existing model systems. Here, we dissect the ciliary role of PC2 by analysing mice carrying a non-ciliary localising, yet channel-functional, PC2 mutation. Mutants develop embryonic renal cysts that appear indistinguishable from mice completely lacking PC2. Despite not entering the cilium in mutant cells, mutant PC2 accumulates at the ciliary base, forming a ring pattern consistent with distal appendage localisation. This suggests a two-step model of ciliary entry; PC2 first traffics to the cilium base before TOP domain dependent entry. Our results suggest that PC2 localisation to the cilium is necessary to prevent PKD., The molecular role of ciliary Polycystin-2 (PC2) in cyst formation and polycystic kidney disease (ADKPD) is unclear. Here, the authors identify a PC2 mutant lacking ciliary localisation but with active Ca2+ channel function in mice, that is sufficient to generate an ADPKD phenotype.
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- 2019
7. Cilia and development
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Dominic P. Norris and Vrinda Sreekumar
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Embryonic Development ,Biology ,Ciliopathies ,03 medical and health sciences ,Human health ,0302 clinical medicine ,Genetics ,Animals ,Humans ,Early lethality ,Cilia ,Body Patterning ,030304 developmental biology ,Regulation of gene expression ,0303 health sciences ,Cilium ,Gene Expression Regulation, Developmental ,Genetic Pleiotropy ,Phenotype ,Mutation ,Signalling pathways ,Neuroscience ,030217 neurology & neurosurgery ,Signal Transduction ,Developmental Biology - Abstract
The role of mammalian cilia in cell signalling was first identified in embryonic development and subsequent analysis has revealed roles in multiple signalling pathways. We now understand that these developmental roles impact human health and this is evident in the class of ciliary diseases which we call the ciliopathies. By their nature cilia defects are usually pleiotropic, affecting more than one system. This often leads to early lethality, meaning that subsequent functions are harder to examine. Current studies are revealing previously unrealised cilia-related phenotypes later in embryonic development. Furthermore, they are exposing the importance of cell biology in understanding the mechanisms of cilia function. In this review, we discuss advances in the field.
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- 2019
8. Nicotine and Cotinine Inhibit Catalase and Glutathione Reductase Activity Contributing to the Impaired Osteogenesis of SCP-1 Cells Exposed to Cigarette Smoke
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Tao Chen, Christian Arnscheidt, Andreas K. Nussler, Sheng Zhu, Bianca Braun, Vrinda Sreekumar, Daniel Heid, Sabrina Ehnert, and Romina H. Aspera-Werz
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0301 basic medicine ,Nicotine ,Aging ,medicine.medical_specialty ,Stromal cell ,Article Subject ,Bone healing ,medicine.disease_cause ,Biochemistry ,Antioxidants ,Cell Line ,03 medical and health sciences ,chemistry.chemical_compound ,Osteogenesis ,Smoke ,Internal medicine ,medicine ,Humans ,lcsh:QH573-671 ,Cotinine ,chemistry.chemical_classification ,Reactive oxygen species ,biology ,lcsh:Cytology ,Mesenchymal stem cell ,Cell Differentiation ,Mesenchymal Stem Cells ,Tobacco Products ,Cell Biology ,General Medicine ,Catalase ,Glutathione Reductase ,030104 developmental biology ,Endocrinology ,chemistry ,biology.protein ,Reactive Oxygen Species ,Oxidative stress ,Research Article ,medicine.drug - Abstract
Cigarette smoking has been identified as a major risk factor for osteoporosis decades ago. Several studies have shown a direct relationship between cigarette smoking, decreased bone mineral density, and impaired fracture healing. However, the mechanisms behind impaired fracture healing and cigarette smoking are yet to be elucidated. Migration and osteogenesis of mesenchymal stem/stromal cells (MSCs) into the fracture site play a vital role in the process of fracture healing. In human nicotine, the most pharmacologically active and major addictive component present in tobacco gets rapidly metabolized to the more stable cotinine. This study demonstrates that physiological concentrations of both nicotine and cotinine do not affect the osteogenic differentiation of MSCs. However, cigarette smoke exposure induces oxidative stress by increasing superoxide radicals and reducing intracellular glutathione in MSCs, negatively affecting osteogenic differentiation. Although, not actively producing reactive oxygen species (ROS) nicotine and cotinine inhibit catalase and glutathione reductase activity, contributing to an accumulation of ROS by cigarette smoke exposure. Coincubation with N-acetylcysteine or L-ascorbate improves impaired osteogenesis caused by cigarette smoke exposure by both activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling and scavenging of ROS, which thus might represent therapeutic targets to support fracture healing in smokers.
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- 2018
9. TGF-β1 impairs mechanosensation of human osteoblasts via HDAC6-mediated shortening and distortion of primary cilia
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Jan G. Hengstler, Gunther H. Sandmann, Christian Bahrs, Vrinda Sreekumar, Sabrina Ehnert, Elke Wintermeyer, Romina H. Aspera-Werz, Patricio Godoy, Andreas K. Nussler, and Sahar Olsadat Sajadian
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0301 basic medicine ,Mechanosensation ,Cell growth ,Cilium ,Osteoblast ,HDAC6 ,Biology ,Bone morphogenetic protein ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,medicine.anatomical_structure ,Microtubule ,Drug Discovery ,medicine ,Molecular Medicine ,Genetics (clinical) ,Transforming growth factor - Abstract
Transforming growth factor β (TGF-β) is a critical regulator of bone density owing to its multiple effects on cell growth and differentiation. Recently, we have shown that TGF-β1 effectively blocks bone morphogenetic protein (BMP) induced maturation of osteoblasts by upregulating histone deacetylase (HDAC) activity. The current study aimed at investigating the effect of rhTGF-β1 treatment on the expression of specific HDACs and their cellular effects, e.g., microtubule structures (primary cilia) and mechanosensation. Exposure to TGF-β1 most significantly induced expression of HDAC6 both on gene and protein level. Being most abundant in the cytoplasm HDAC6 effectively deacetylates microtubule structures. Thus, TGF-β1-induced expression of HDAC6 led to deformation and shortening of primary cilia as well as to reduced numbers of ciliated cells. Primary cilia are described to sense mechanical stimuli. Thus, fluid flow was applied to the cells, which stimulated osteoblast function (AP activity and matrix mineralization). Compromised primary cilia in TGF-β1-treated cells were associated with reduced osteogenic function, despite exposure to fluid flow conditions. Chemical inhibition of HDAC6 with Tubacin restored primary cilium structure and length. These cells showed improved osteogenic function especially under fluid flow conditions. Summarizing our results, TGF-β1 impairs human osteoblast maturation partially via HDAC6-mediated distortion and/or shortening of primary cilia. This knowledge opens up new treatment options for trauma patients with chronically elevated TGF-β1-levels (e.g., diabetics), which frequently suffer from delayed fracture healing despite adequate mechanical stimulation.
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- 2017
10. BMP9 a possible alternative drug for the recently withdrawn BMP7? New perspectives for (re-)implementation by personalized medicine
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Ingo Flesch, Sabrina Ehnert, Thomas Freude, Valeska Hofmann, Katja Breitkopf-Heinlein, Marie K. Reumann, Steven Dooley, Romina H. Aspera-Werz, Stefan Pscherer, Vrinda Sreekumar, Gauri Tendulkar, Andreas K. Nussler, and Björn Gunnar Ochs
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0301 basic medicine ,medicine.medical_specialty ,Cell Survival ,Bone Morphogenetic Protein 7 ,Health, Toxicology and Mutagenesis ,Bone Morphogenetic Protein 2 ,Bone healing ,Toxicology ,Bioinformatics ,Safety-Based Drug Withdrawals ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Growth Differentiation Factor 2 ,Humans ,Medicine ,Noggin ,Bone regeneration ,Cells, Cultured ,Osteoblasts ,biology ,business.industry ,RANK Ligand ,Osteoprotegerin ,General Medicine ,Endoglin ,Alkaline Phosphatase ,Recombinant Proteins ,Wnt Proteins ,Bone morphogenetic protein 7 ,030104 developmental biology ,Endocrinology ,Gene Expression Regulation ,RANKL ,030220 oncology & carcinogenesis ,Bone Morphogenetic Proteins ,biology.protein ,BAMBI ,Personalized medicine ,business - Abstract
Promotion of rhBMP2 and rhBMP7 for the routine use to support fracture healing has been hampered by high costs, safety concerns and reasonable failure rates, imposing restrictions in its clinical use. Since there is little debate regarding its treatment potential, there is rising need for a better understanding of the mode of action of these BMPs to overcome its drawbacks and promote more efficacious treatment strategies for bone regeneration. Recently, BMP9, owing to its improved osteogenic potential, is gaining attention as a promising therapeutic alternative. Our study aimed at identifying specific gene expression patterns which may predict and explain individual responses to rhBMP7 and rhBMP9 treatments. Therefore, we investigated the effect of rhBMP7 and rhBMP9 on primary human osteoblasts from 110 donors and corresponding THP-1-derived osteoclasts. This was further compared with each other and our reported data on rhBMP2 response. Based on the individual donor response, we found three donor groups profiting from rhBMP treatment either directly via stimulation of osteoblast function or viability and/or indirectly via inhibition of osteoclasts. The response on rhBMP7 treatment correlated with expression levels of the genes BAMBI, SOST, Noggin, Smad4 and RANKL, while the response of rhBMP9 correlated to the expression levels of Alk6, Endoglin, Smurf1, Smurf2, SOST and RANKL in these donors. Noteworthy, rhBMP9 treatment showed significantly increased osteogenic activity (AP activity and Smad nuclear translocation) when compared to the two clinically used rhBMPs. Based on patient's respective expression profiles, clinical application of rhBMP9 either solely or in combination with rhBMP2 and/or rhBMP7 can become a promising new approach to fit the patient's needs to promote fracture healing.
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- 2016
11. Resveratrol protects primary cilia integrity of human mesenchymal stem cells from cigarette smoke to improve osteogenic differentiation in vitro
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Gauri Tendulkar, Vrinda Sreekumar, Andreas K. Nussler, Julius Strobel, Christian Arnscheidt, Daniel Heid, Anna J. Schreiner, Sabrina Ehnert, and Romina H. Aspera-Werz
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0301 basic medicine ,Free Radicals ,Health, Toxicology and Mutagenesis ,Resveratrol ,Biology ,Toxicology ,Antioxidants ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Microtubule ,Osteogenesis ,Smoke ,Tobacco ,Humans ,Cilia ,Bone regeneration ,Transcription factor ,Cells, Cultured ,chemistry.chemical_classification ,Reactive oxygen species ,Cilium ,Mesenchymal stem cell ,Cell Differentiation ,Mesenchymal Stem Cells ,General Medicine ,In vitro ,Cell biology ,030104 developmental biology ,chemistry ,Gene Expression Regulation ,Cytoprotection ,030220 oncology & carcinogenesis - Abstract
Several studies have explored the negative effects of cigarette smoke on bone healing; however, the complex pathogenesis still remains unclear. One crucial and primary factor determining effective fracture repair is the recruitment and differentiation of mesenchymal stem cells (MSCs) into bone-forming cells. Recently, primary cilia, microtubule-based sensory organelles, have been shown to be critical in lineage commitment and differentiation of MSCs. Our present study indicates that exposure to cigarette smoke extract (CSE 0.1–10%) impaired osteogenic differentiation of human mesenchymal stem cell line (SCP-1) and interestingly, also affected primary cilia distribution and integrity in these cells during the differentiation. Furthermore, significant amounts of free radicals generated by CSE could be causative of primary cilia loss since treatment with 0.01% of hydrogen peroxide, a prime free radical in CSE, destroyed primary cilia in these cells. The debilitated differentiation of CSE-exposed SCP-1 cells also correlated with the significantly reduced expression of transcription factor and target genes of primary cilia-specific hedgehog signalling, a key player in osteogenic differentiation. As a treatment strategy, co-incubation of the CSE-exposed SCP-1 cells with the antioxidant resveratrol (1 µM) had a protective effect as it significantly reduced free radical production, protected the primary cilia and enhanced osteogenic differentiation. The current study shows for the first time that cigarette smoke affects primary cilia in human MSCs during osteogenic differentiation and treatment with resveratrol could reverse the effects and enhance differentiation, thus opening up potential therapeutic alternatives to treat fracture healing in smokers, in particularly, when delayed fracture healing is assumed.
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- 2017
12. TGF-β
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Sabrina, Ehnert, Vrinda, Sreekumar, Romina H, Aspera-Werz, Sahar O, Sajadian, Elke, Wintermeyer, Gunther H, Sandmann, Christian, Bahrs, Jan G, Hengstler, Patricio, Godoy, and Andreas K, Nussler
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Male ,Osteoblasts ,Middle Aged ,Histone Deacetylase 6 ,Hydroxamic Acids ,Mechanotransduction, Cellular ,Histone Deacetylase Inhibitors ,Transforming Growth Factor beta1 ,Osteogenesis ,Humans ,Anilides ,Female ,Cilia ,Cells, Cultured ,Aged - Abstract
Transforming growth factor β (TGF-β) is a critical regulator of bone density owing to its multiple effects on cell growth and differentiation. Recently, we have shown that TGF-βExposure to TGF-β
- Published
- 2016
13. Spastic Paraplegia Mutation N256S in the Neuronal Microtubule Motor KIF5A Disrupts Axonal Transport in a Drosophila HSP Model
- Author
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Petra Füger, Vrinda Sreekumar, Rebecca Schüle, Jeannine V. Kern, Doychin T. Stanchev, Carola D. Schneider, Kathrin N. Karle, Katharina J. Daub, Vera K. Siegert, Matthias Flötenmeyer, Heinz Schwarz, Ludger Schöls, and Tobias M. Rasse
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Cancer Research ,lcsh:Genetics ,lcsh:QH426-470 ,Genetics ,Correction ,QH426-470 ,Molecular Biology ,Genetics (clinical) ,Ecology, Evolution, Behavior and Systematics - Published
- 2013
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