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Publications (10 of 19) Show all publications
Mushtaq, F., Nadeem, A., Yabrag, A., Bala, A., Karah, N., Zlatkov, N., . . . Ahmad, I. (2024). Colony phase variation switch modulates antimicrobial tolerance and biofilm formation in Acinetobacter baumannii. Microbiology Spectrum, 12(2), Article ID e02956-23.
Open this publication in new window or tab >>Colony phase variation switch modulates antimicrobial tolerance and biofilm formation in Acinetobacter baumannii
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2024 (English)In: Microbiology Spectrum, E-ISSN 2165-0497, Vol. 12, no 2, article id e02956-23Article in journal (Refereed) Published
Abstract [en]

Carbapenem-resistant Acinetobacter baumannii causes one of the most difficult-to-treat nosocomial infections. Polycationic drugs like polymyxin B or colistin and tetracycline drugs such as doxycycline or minocycline are commonly used to treat infections caused by carbapenem-resistant A. baumannii. Here, we show that a subpopulation of cells associated with the opaque/translucent colony phase variation by A. baumannii AB5075 displays differential tolerance to subinhibitory concentrations of colistin and tetracycline. Using a variety of microscopic techniques, we demonstrate that extracellular polysaccharide moieties mediate colistin tolerance to opaque A. baumannii at single-cell level and that mushroom-shaped biofilm structures protect opaque bacteria at the community level. The colony switch phenotype is found to alter several traits of A. baumannii, including long-term survival under desiccation, tolerance to ethanol, competition with Escherichia coli, and intracellular survival in the environmental model host Acanthamoeba castellanii. Additionally, our findings suggest that extracellular DNA associated with membrane vesicles can promote colony switching in a DNA recombinase-dependent manner.

Importance: As a WHO top-priority drug-resistant microbe, Acinetobacter baumannii significantly contributes to hospital-associated infections worldwide. One particularly intriguing aspect is its ability to reversibly switch its colony morphotype on agar plates, which has been remarkably underexplored. In this study, we employed various microscopic techniques and phenotypic assays to investigate the colony phase variation switch under different clinically and environmentally relevant conditions. Our findings reveal that the presence of a poly N-acetylglucosamine-positive extracellular matrix layer contributes to the protection of bacteria from the bactericidal effects of colistin. Furthermore, we provide intriguing insights into the multicellular lifestyle of A. baumannii, specifically in the context of colony switch variation within its predatory host, Acanthamoeba castellanii.

Place, publisher, year, edition, pages
American Society for Microbiology, 2024
Keywords
colisitin, opaque colony, translucent colony
National Category
Infectious Medicine Microbiology in the medical area
Identifiers
urn:nbn:se:umu:diva-221121 (URN)10.1128/spectrum.02956-23 (DOI)001141161500001 ()38205963 (PubMedID)2-s2.0-85184519514 (Scopus ID)
Funder
Swedish Research Council, 2020-06136Swedish Research Council, 2019-01720Swedish Research Council, 2018-02914Swedish Research Council, 2016-00968Swedish Research Council, 2019-00217The Kempe Foundations, SMK-1961The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IB2022-9222Swedish Cancer Society, 2017-419
Available from: 2024-02-20 Created: 2024-02-20 Last updated: 2024-02-20Bibliographically approved
Ahmad, I., Nadeem, A., Mushtaq, F., Zlatkov, N., Shahzad, M., Zavialov, A. V., . . . Uhlin, B. E. (2023). Csu pili dependent biofilm formation and virulence of Acinetobacter baumannii. npj Biofilms and Microbiomes, 9(1), Article ID 101.
Open this publication in new window or tab >>Csu pili dependent biofilm formation and virulence of Acinetobacter baumannii
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2023 (English)In: npj Biofilms and Microbiomes, E-ISSN 2055-5008, Vol. 9, no 1, article id 101Article in journal (Refereed) Published
Abstract [en]

Acinetobacter baumannii has emerged as one of the most common extensive drug-resistant nosocomial bacterial pathogens. Not only can the bacteria survive in hospital settings for long periods, but they are also able to resist adverse conditions. However, underlying regulatory mechanisms that allow A. baumannii to cope with these conditions and mediate its virulence are poorly understood. Here, we show that bi-stable expression of the Csu pili, along with the production of poly-N-acetyl glucosamine, regulates the formation of Mountain-like biofilm-patches on glass surfaces to protect bacteria from the bactericidal effect of colistin. Csu pilus assembly is found to be an essential component of mature biofilms formed on glass surfaces and of pellicles. By using several microscopic techniques, we show that clinical isolates of A. baumannii carrying abundant Csu pili mediate adherence to epithelial cells. In addition, Csu pili suppressed surface-associated motility but enhanced colonization of bacteria into the lungs, spleen, and liver in a mouse model of systemic infection. The screening of c-di-GMP metabolizing protein mutants of A. baumannii 17978 for the capability to adhere to epithelial cells led us to identify GGDEF/EAL protein AIS_2337, here denoted PdeB, as a major regulator of Csu pili-mediated virulence and biofilm formation. Moreover, PdeB was found to be involved in the type IV pili-regulated robustness of surface-associated motility. Our findings suggest that the Csu pilus is not only a functional component of mature A. baumannii biofilms but also a major virulence factor promoting the initiation of disease progression by mediating bacterial adherence to epithelial cells.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Microbiology in the medical area
Identifiers
urn:nbn:se:umu:diva-218629 (URN)10.1038/s41522-023-00465-6 (DOI)38097635 (PubMedID)2-s2.0-85179677116 (Scopus ID)
Funder
Swedish Research Council, 2020-06136Swedish Research Council, 2020-06136Swedish Research Council, 2018-02914Swedish Research Council, 2022-04779The Kempe Foundations, SMK-1961The Kempe Foundations, SMK21-0076Umeå University, FS 2.1.6–1776-19Umeå University, 2021-2023The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Swedish Cancer Society, 2017-419
Available from: 2023-12-27 Created: 2023-12-27 Last updated: 2023-12-27Bibliographically approved
Farag, S., Francis, M. K., Gurung, J. M., Wai, S. N., Stenlund, H., Francis, M. S. & Nadeem, A. (2023). Macrophage innate immune responses delineate between defective translocon assemblies produced by Yersinia pseudotuberculosis YopD mutants. Virulence, 14(1), Article ID 2249790.
Open this publication in new window or tab >>Macrophage innate immune responses delineate between defective translocon assemblies produced by Yersinia pseudotuberculosis YopD mutants
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2023 (English)In: Virulence, ISSN 2150-5594, E-ISSN 2150-5608, Vol. 14, no 1, article id 2249790Article in journal (Refereed) Published
Abstract [en]

Translocon pores formed in the eukaryotic cell membrane by a type III secretion system facilitate the translocation of immune-modulatory effector proteins into the host cell interior. The YopB and YopD proteins produced and secreted by pathogenic Yersinia spp. harboring a virulence plasmid-encoded type III secretion system perform this pore-forming translocator function. We had previously characterized in vitro T3SS function and in vivo pathogenicity of a number of strains encoding sited-directed point mutations in yopD. This resulted in the classification of mutants into three different classes based upon the severity of the phenotypic defects. To investigate the molecular and functional basis for these defects, we explored the effectiveness of RAW 264.7 cell line to respond to infection by representative YopD mutants of all three classes. Signature cytokine profiles could separate the different YopD mutants into distinct categories. The activation and suppression of certain cytokines that function as central innate immune response modulators correlated well with the ability of mutant bacteria to alter anti-phagocytosis and programmed cell death pathways. These analyses demonstrated that sub-optimal translocon pores impact the extent and magnitude of host cell responsiveness, and this limits the capacity of pathogenic Yersinia spp. to fortify against attack by both early and late arms of the host innate immune response.

Place, publisher, year, edition, pages
London: Taylor & Francis Group, 2023
Keywords
Cytokine profiling, inflammasome, programmed cell death, anti-phagocytosis, translocon complexes, bacteria-eukaryotic cell contact
National Category
Microbiology in the medical area Microbiology
Research subject
Microbiology; Molecular Biology
Identifiers
urn:nbn:se:umu:diva-213952 (URN)10.1080/21505594.2023.2249790 (DOI)37621095 (PubMedID)2-s2.0-85168743016 (Scopus ID)
Funder
Swedish Research Council, 2014-2105Umeå UniversitySwedish Research Council, 2018-02676Swedish Research Council, 2022-04779Swedish Research Council, 2018-02914The Kempe Foundations
Available from: 2023-08-31 Created: 2023-08-31 Last updated: 2023-09-07Bibliographically approved
Toh, E., Baryalai, P., Nadeem, A., Aung, K. M., Chen, S., Persson, K., . . . Wai, S. N. (2022). Bacterial protein MakA causes suppression of tumour cell proliferation via inhibition of PIP5K1α/Akt signalling. Cell Death and Disease, 13(12), Article ID 1024.
Open this publication in new window or tab >>Bacterial protein MakA causes suppression of tumour cell proliferation via inhibition of PIP5K1α/Akt signalling
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2022 (English)In: Cell Death and Disease, ISSN 2041-4889, E-ISSN 2041-4889, Vol. 13, no 12, article id 1024Article in journal (Refereed) Published
Abstract [en]

Recently, we demonstrated that a novel bacterial cytotoxin, the protein MakA which is released by Vibrio cholerae, is a virulence factor, causing killing of Caenorhabditis elegans when the worms are grazing on the bacteria. Studies with mammalian cell cultures in vitro indicated that MakA could affect eukaryotic cell signalling pathways involved in lipid biosynthesis. MakA treatment of colon cancer cells in vitro caused inhibition of growth and loss of cell viability. These findings prompted us to investigate possible signalling pathways that could be targets of the MakA-mediated inhibition of tumour cell proliferation. Initial in vivo studies with MakA producing V. cholerae and C. elegans suggested that the MakA protein might target the PIP5K1α phospholipid-signalling pathway in the worms. Intriguingly, MakA was then found to inhibit the PIP5K1α lipid-signalling pathway in cancer cells, resulting in a decrease in PIP5K1α and pAkt expression. Further analyses revealed that MakA inhibited cyclin-dependent kinase 1 (CDK1) and induced p27 expression, resulting in G2/M cell cycle arrest. Moreover, MakA induced downregulation of Ki67 and cyclin D1, which led to inhibition of cell proliferation. This is the first report about a bacterial protein that may target signalling involving the cancer cell lipid modulator PIP5K1α in colon cancer cells, implying an anti-cancer effect.

Place, publisher, year, edition, pages
Springer Nature, 2022
National Category
Microbiology in the medical area
Identifiers
urn:nbn:se:umu:diva-201753 (URN)10.1038/s41419-022-05480-7 (DOI)000895373300001 ()36473840 (PubMedID)2-s2.0-85143300255 (Scopus ID)
Funder
Swedish Research Council, 2018-02914Swedish Research Council, 2019-01720Swedish Research Council, 2019-01318Swedish Research Council, 2016-05009Swedish Cancer Society, CAN-2017-419Swedish Cancer Society, 2020-711Swedish Cancer Society, CAN-2017-381The Kempe Foundations, JCK-1728The Kempe Foundations, SMK-1553The Kempe Foundations, JCK2931.1U9Malmö University
Available from: 2022-12-21 Created: 2022-12-21 Last updated: 2023-09-05Bibliographically approved
Liu, Y., Nadeem, A., Sebastian, S., Olsson, M. A., Wai, S. N., Styring, E., . . . Raina, D. B. (2022). Bone mineral: A trojan horse for bone cancers. Efficient mitochondria targeted delivery and tumor eradication with nano hydroxyapatite containing doxorubicin. Materials Today Bio, 14, Article ID 100227.
Open this publication in new window or tab >>Bone mineral: A trojan horse for bone cancers. Efficient mitochondria targeted delivery and tumor eradication with nano hydroxyapatite containing doxorubicin
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2022 (English)In: Materials Today Bio, E-ISSN 2590-0064, Vol. 14, article id 100227Article in journal (Refereed) Published
Abstract [en]

Efficient systemic pharmacological treatment of solid tumors is hampered by inadequate tumor concentration of cytostatics necessitating development of smart local drug delivery systems. To overcome this, we demonstrate that doxorubicin (DOX), a cornerstone drug used for osteosarcoma treatment, shows reversible accretion to hydroxyapatite (HA) of both nano (nHA) and micro (mHA) size. nHA particles functionalized with DOX get engulfed in the lysosome of osteosarcoma cells where the acidic microenvironment causes a disruption of the binding between DOX and HA. The released DOX then accumulates in the mitochondria causing cell starvation, reduced migration and apoptosis. The HA+DOX delivery system was also tested in-vivo on osteosarcoma bearing mice. Locally delivered DOX via the HA particles had a stronger tumor eradication effect compared to the controls as seen by PET-CT and immunohistochemical staining of proliferation and apoptosis markers. These results indicate that in addition to systemic chemotherapy, an adjuvant nHA could be used as a carrier for intracellular delivery of DOX for prevention of tumor recurrence after surgical resection in an osteosarcoma. Furthermore, we demonstrate that nHA particles are pivotal in this approach but a combination of nHA with mHA could increase the safety associated with particulate nanomaterials while maintaining similar therapeutic potential.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Doxorubicin, Drug delivery, Nano and micro hydroxyapatite, Osteosarcoma, Solid tumor
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:umu:diva-193012 (URN)10.1016/j.mtbio.2022.100227 (DOI)000819915800003 ()2-s2.0-85125537714 (Scopus ID)
Available from: 2022-03-14 Created: 2022-03-14 Last updated: 2023-09-05Bibliographically approved
Hansen, F. C., Nadeem, A., Browning, K. L., Campana, M., Schmidtchen, A. & Van Der Plas, M. J. .. (2022). Differential Internalization of Thrombin-Derived Host Defense Peptides into Monocytes and Macrophages. Journal of Innate Immunity, 14, 418-432
Open this publication in new window or tab >>Differential Internalization of Thrombin-Derived Host Defense Peptides into Monocytes and Macrophages
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2022 (English)In: Journal of Innate Immunity, ISSN 1662-811X, E-ISSN 1662-8128, Vol. 14, p. 418-432Article in journal (Refereed) Published
Abstract [en]

Proteolytic cleavage of thrombin generates C-terminal host defense peptides exerting multiple immunomodulatory effects in response to bacterial stimuli. Previously, we reported that thrombin-derived C-terminal peptides (TCPs) are internalized in monocytes and macrophages in a time- and temperature-dependent manner. In this study, we investigated which endocytosis pathways are responsible for the internalization of TCPs. Using confocal microscopy and flow cytometry, we show that both clathrin-dependent and clathrin-independent pathways are involved in the internalization of the prototypic TCP GKY25 in RAW264.7 and human monocyte-derived M1 macrophages, whereas the uptake of GKY25 in monocytic THP-1 cells is mainly dynamin-dependent. Internalized GKY25 was transported to endosomes and finally lysosomes, where it remained detectable for up to 10 h. Comparison of GKY25 uptake with that of the natural occurring TCPs HVF18 and FYT21 indicates that the pathway of TCP endocytosis is not only cell type-dependent but also depends on the length and composition of the peptide as well as the presence of LPS and bacteria. Finally, using neutron reflectometry, we show that the observed differences between HVF18 and the other 2 TCPs may be explained partially by differences in membrane insertion. Taken together, we show that TCPs are differentially internalized into monocytes and macrophages.

Place, publisher, year, edition, pages
S. Karger, 2022
Keywords
Bacterial infection, Caveolin-dependent endocytosis, Clathrin-dependent endocytosis, Host defense peptides, Lysosomes, Thrombin
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-190980 (URN)10.1159/000520831 (DOI)000733427400001 ()34937021 (PubMedID)2-s2.0-85121767245 (Scopus ID)
Funder
O.E. och Edla Johanssons vetenskapliga stiftelseÅke Wiberg FoundationSwedish Foundation for Strategic ResearchKnut and Alice Wallenberg FoundationSwedish Research Council, 2017-02341Swedish Research Council, 2020-02016
Available from: 2022-01-04 Created: 2022-01-04 Last updated: 2023-03-24Bibliographically approved
Schmidtchen, A., Mirza, H., van der Plas, M. J. A., Nadeem, A. & Puthia, M. (2022). Editorial: methods and applications in inflammation pharmacology. Frontiers in Pharmacology, 13, Article ID 1108263.
Open this publication in new window or tab >>Editorial: methods and applications in inflammation pharmacology
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2022 (English)In: Frontiers in Pharmacology, E-ISSN 1663-9812, Vol. 13, article id 1108263Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
Frontiers Media S.A., 2022
Keywords
animal models, inflammation, innate immunity, pharmacology, preclinical
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:umu:diva-202232 (URN)10.3389/fphar.2022.1108263 (DOI)36578538 (PubMedID)2-s2.0-85144922244 (Scopus ID)
Available from: 2023-01-05 Created: 2023-01-05 Last updated: 2024-01-17Bibliographically approved
Nadeem, A., Berg, A., Pace, H., Alam, A., Toh, E., Ådén, J., . . . Wai, S. N. (2022). Protein-lipid interaction at low pH induces oligomerization of the MakA cytotoxin from Vibrio cholerae. eLIFE, 11, Article ID e73439.
Open this publication in new window or tab >>Protein-lipid interaction at low pH induces oligomerization of the MakA cytotoxin from Vibrio cholerae
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2022 (English)In: eLIFE, E-ISSN 2050-084X, Vol. 11, article id e73439Article in journal (Refereed) Published
Abstract [en]

The α-pore-forming toxins (α-PFTs) from pathogenic bacteria damage host cell membranes by pore formation. We demonstrate a remarkable, hitherto unknown mechanism by an α-PFT protein from Vibrio cholerae. As part of the MakA/B/E tripartite toxin, MakA is involved in membrane pore formation similar to other α-PFTs. In contrast, MakA in isolation induces tube-like structures in acidic endosomal compartments of epithelial cells in vitro. The present study unravels the dynamics of tubular growth, which occurs in a pH-, lipid-, and concentration-dependent manner. Within acidified organelle lumens or when incubated with cells in acidic media, MakA forms oligomers and remodels membranes into high-curvature tubes leading to loss of membrane integrity. A 3.7 Å cryo-electron microscopy structure of MakA filaments reveals a unique protein-lipid superstructure. MakA forms a pinecone-like spiral with a central cavity and a thin annular lipid bilayer embedded between the MakA transmembrane helices in its active α-PFT conformation. Our study provides insights into a novel tubulation mechanism of an α-PFT protein and a new mode of action by a secreted bacterial toxin.

Place, publisher, year, edition, pages
eLife Sciences Publications, Ltd, 2022
Keywords
Vibrio cholerae, MakA, lipid
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-192300 (URN)10.7554/eLife.73439 (DOI)2-s2.0-85124321786 (Scopus ID)
Funder
Swedish Research Council, 2018–02914Swedish Research Council, 2016–05009Swedish Research Council, 2019–01720Swedish Research Council, 2016–06963Swedish Research Council, 2019–02011Swedish Cancer Society, 2017–419Swedish Cancer Society, 2020–711The Kempe Foundations, JCK-1728The Kempe Foundations, SMK-1756.2The Kempe Foundations, SMK-1553The Kempe Foundations, JCK-1724The Kempe Foundations, SMK-1961Knut and Alice Wallenberg FoundationFamiljen Erling-Perssons Stiftelse
Available from: 2022-02-08 Created: 2022-02-08 Last updated: 2024-01-12Bibliographically approved
Nadeem, A., Nagampalli, R., Toh, E., Alam, A., Myint, S. L., Heidler, T., . . . Persson, K. (2021). A tripartite cytolytic toxin formed by Vibrio cholerae proteins with flagellum-facilitated secretion. Proceedings of the National Academy of Sciences of the United States of America, 118(47), Article ID e2111418118.
Open this publication in new window or tab >>A tripartite cytolytic toxin formed by Vibrio cholerae proteins with flagellum-facilitated secretion
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2021 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 118, no 47, article id e2111418118Article in journal (Refereed) Published
Abstract [en]

Vibrio cholerae, responsible for outbreaks of cholera disease, is a highly motile organism by virtue of a single flagellum. We describe how the flagellum facilitates the secretion of three V. cholerae proteins encoded by a hitherto-unrecognized genomic island. The proteins MakA/B/E can form a tripartite toxin that lyses erythrocytes and is cytotoxic to cultured human cells. A structural basis for the cytolytic activity of the Mak proteins was obtained by X-ray crystallography. Flagellum-facilitated secretion ensuring spatially coordinated delivery of Mak proteins revealed a role for the V. cholerae flagellum considered of particular significance for the bacterial environmental persistence. Our findings will pave the way for the development of diagnostics and therapeutic strategies against pathogenic Vibrionaceae.

National Category
Biochemistry and Molecular Biology
Research subject
Biochemistry
Identifiers
urn:nbn:se:umu:diva-191257 (URN)10.1073/pnas.2111418118 (DOI)000727697700014 ()34799450 (PubMedID)2-s2.0-85121209218 (Scopus ID)
Funder
Swedish Research Council, 2016-05009Swedish Research Council, 2018-02914Swedish Research Council, 2019-01720Swedish Research Council, 2007-08673The Kempe Foundations, SMK-1756.2The Kempe Foundations, SMK-1553The Kempe Foundations, JCK-1728Swedish Cancer Society, 2017-419The Kempe Foundations, SMK-1961Swedish Research Council
Available from: 2022-01-12 Created: 2022-01-12 Last updated: 2023-05-11Bibliographically approved
Zlatkov, N., Nadeem, A., Uhlin, B. E. & Wai, S. N. (2021). Eco-evolutionary feedbacks mediated by bacterial membrane vesicles. FEMS Microbiology Reviews, 45(2), Article ID fuaa047.
Open this publication in new window or tab >>Eco-evolutionary feedbacks mediated by bacterial membrane vesicles
2021 (English)In: FEMS Microbiology Reviews, ISSN 0168-6445, E-ISSN 1574-6976, Vol. 45, no 2, article id fuaa047Article in journal (Refereed) Published
Abstract [en]

Bacterial membrane vesicles (BMVs) are spherical extracellular organelles whose cargo is enclosed by a biological membrane. The cargo can be delivered to distant parts of a given habitat in a protected and concentrated manner. This review presents current knowledge about BMVs in the context of bacterial eco-evolutionary dynamics among different environments and hosts. BMVs may play an important role in establishing and stabilizing bacterial communities in such environments; for example, bacterial populations may benefit from BMVs to delay the negative effect of certain evolutionary trade-offs that can result in deleterious phenotypes. BMVs can also perform ecosystem engineering by serving as detergents, mediators in biochemical cycles, components of different biofilms, substrates for cross-feeding, defense systems against different dangers and enzyme-delivery mechanisms that can change substrate availability. BMVs further contribute to bacteria as mediators in different interactions, with either other bacterial species or their hosts. In short, BMVs extend and deliver phenotypic traits that can have ecological and evolutionary value to both their producers and the ecosystem as a whole.

Place, publisher, year, edition, pages
Oxford University Press, 2021
Keywords
bacterial membrane vesicles, ecology, evolution
National Category
Microbiology
Identifiers
urn:nbn:se:umu:diva-182115 (URN)10.1093/femsre/fuaa047 (DOI)000637053600001 ()2-s2.0-85103227807 (Scopus ID)
Funder
Swedish Research Council, 2015-03007Swedish Research Council, 2015-06824Swedish Research Council, 2016- 06598Swedish Research Council, 2018-02914Swedish Research Council, 2019-01720Swedish Research Council, 349-2007-8673The Kempe Foundations, JCK-1724The Kempe Foundations, JCK-1728Swedish Cancer Society, 2017-419
Available from: 2021-04-09 Created: 2021-04-09 Last updated: 2023-09-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1439-6216

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