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  • 201.
    Danielson, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Alfredson, Håkan
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Marked occurrence of receptors for sympathetic and cholinergic transmitters and for substance P in the blood vessels of the human patellar tendon.2005Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION: Human tendons have generally been considered to be hyponeural. However, in our recent studies of the patellar tendon in both healthy individuals and patients with tendinosis (jumper’s knee), we have noted the presence of general (PGP 9.5) and sensory (substance P [SP]) innervations, especially in the loose paratendinous connective tissue. Furthermore, we have observed a pronounced expression of the neurokinin-1 receptor (the preferred receptor for SP) in blood vessel walls. The findings are of interest as a new successful treatment of tendinosis has emerged in form of doppler guided sclerosing injections (substance: Polidokanol), targeting areas with neovascularisation, and as SP is known to be of importance when neurogenic angiogenesis participates in diseases. AIM: To further investigate the blood vessels of the normal and tendinosis-affected human patellar tendon regarding autonomic innervation. METHODS: Immunohistochemistry and histochemistry, including antibodies against the sympathetic nerve markers tyroxine hydroxylase and neuropeptide Y and against various adrenoreceptors (α1, α2a, β1), as well as stainings for substances related to cholinergic functions such as the muscarinic M2 receptor, acetylcholinesterase and vesicular acetylcholine transporter. RESULTS/CONCLUSIONS: The preliminary results so far, indicate that there is indeed an occurrence of both sympathetic and cholinergic innervations in the tendon, not the least shown via the presence of sympathetic and cholinergic receptors in blood vessel walls; a fact that further supports the theories that blood vessel regulation via neurotransmitters/-modulators might be a key factor in the pathological mechanisms of jumper’s knee.

  • 202.
    Danielson, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Anatomi.
    Alfredson, Håkan
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Anatomi.
    Studies on the importance of sympathetic innervation, adrenergic receptors, and a possible local catecholamine production in the development of patellar tendinopathy (tendinosis) in man.2007In: Microscopy research and technique (Print), ISSN 1059-910X, E-ISSN 1097-0029, Vol. 70, no 4, p. 310-324Article in journal (Refereed)
    Abstract [en]

    Changes in the patterns of production and in the effects of signal substances may be involved in the development of tendinosis, a chronic condition of pain in human tendons. There is no previous information concerning the patterns of sympathetic innervation in the human patellar tendon. In this study, biopsies of normal and tendinosis patellar tendons were investigated with immunohistochemical methods, including the use of antibodies against tyrosine hydroxylase (TH) and neuropeptide Y, and against alpha(1)-, alpha(2A)-, and beta(1)-adrenoreceptors. It was noticed that most of the sympathetic innervation was detected in the walls of the blood vessels entering the tendon through the paratendinous tissue, and that the tendon tissue proper of the normal and tendinosis tendons was very scarcely innervated. Immunoreactions for adrenergic receptors were noticed in nerve fascicles containing both sensory and sympathetic nerve fibers. High levels of these receptors were also detected in the blood vessel walls; alpha(1)-adrenoreceptor immunoreactions being clearly more pronounced in the tendinosis tendons than in the tendons of controls. Interestingly, immunoreactions for adrenergic receptors and TH were noted for the tendon cells (tenocytes), especially in tendinosis tendons. The findings give a morphological correlate for the occurrence of sympathetically mediated effects in the patellar tendon and autocrine/paracrine catecholamine mechanisms for the tenocytes, particularly, in tendinosis. The observation of adrenergic receptors on tenocytes is interesting, as stimulation of these receptors can lead to cell proliferation, degeneration, and apoptosis, events which are all known to occur in tendinosis. Furthermore, the results imply that a possible source of catecholamine production might be the tenocytes themselves. Microsc. Res. Tech., 2007. (c) 2007 Wiley-Liss, Inc.

  • 203.
    Danielson, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Anatomi.
    Andersson, Gustav
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Alfredson, Håkan
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Anatomi.
    Extensive expression of markers for acetylcholine synthesis and of M2 receptors in tenocytes in therapy-resistant chronic painful patellar tendon tendinosis - a pilot study.2007In: Life Sciences, ISSN 0024-3205, E-ISSN 1879-0631, Vol. 80, no 24-25, p. 2235-2238Article in journal (Refereed)
    Abstract [en]

    We have recently obtained evidence favoring the occurrence of an up-regulation of a non-neuronal cholinergic system in chronic painful patellar tendon tendinosis. It seems possible that this up-regulation to a certain degree may be involved in the manifestations of the disease. Today, there is a new, very successful, line of treatment of patellar tendinosis in the form of Doppler guided sclerosing injections. However, a few patients seem resistant to this therapy. Therefore, we have in this pilot study investigated biopsies from the patellar tendon of three such therapy-resistant patients, using immunohistochemistry. In situ hybridization was also applied. Comparisons were made with a material of specimens from both normal (n=16) and tendinosis (n=7) tendons, also previously examined. The study showed that there were extensive immunoreactions for choline acetyltransferase (ChAT) and vesicular acetylcholine transporter, as well as for the M(2) muscarinic acetylcholine receptor, in the overwhelming majority of the tenocytes. The immunoreactions were more pronounced than those generally obtained in the tendinosis tissue of the previously studied patients and clearly more pronounced than those of patellar tendon tissue of controls. Also, for the first time, we here present findings of mRNA for ChAT within tenocytes. In conclusion, it appears as if there is an excessive local acetylcholine (ACh) production and an occurrence of marked ACh effects in cases of severe tendinosis. An excessive production of local ACh might be related to pain sensation and the processes that occur in tendinosis development, such as cell proliferation. Thus, the results of this pilot study suggest that non-neuronal ACh is highly involved in the pathology of therapy-resistant patellar tendinosis.

  • 204.
    Danielson, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Andersson, Gustav
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Alfredson, Håkan
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Forsgren, Sture
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Marked sympathetic component in the perivascular innervation of the dorsal paratendinous tissue of the patellar tendon in arthroscopically treated tendinosis patients.2008In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 16, no 6, p. 621-6Article in journal (Refereed)
    Abstract [en]

    During the recent years, a few studies have shed new light on the innervation patterns of the human patellar tendon, but the area of the loose paratendinous connective tissue dorsal to the proximal tendon proper has yet not been investigated. That is a drawback, since this is the area targeted in promising treatment regimens of chronic painful patellar tendinosis, namely sclerosing Polidocanol injection therapy, and a new surgical method conforming to ultrasound and color Doppler guided arthroscopic shaving, directed at neovessels found in the region. The present study thus aimed at investigating the paratendinous area dorsal to the proximal patellar tendon proper in seven patients being operated for tendinosis. Biopsies were collected through the new arthroscopic technique, approaching the tendon from the dorsal side. Samples were investigated using immunohistochemistry with antibodies delineating general (PGP 9.5), sensory (SP/CGRP), and sympathetic (TH/NPY) nerve patterns, and also antibodies against alpha1- and alpha2A-adrenoreceptors. Both small and large blood vessels had a marked perivascular innervation (PGP 9.5). Surprisingly, this perivascular innervation was found only to a very limited extent to correspond to sensory nerves, while there were marked immunoreactions for sympathetic markers. Adrenoreceptor immunoreactions frequently occurred in blood vessel walls. In conclusion, this study demonstrates, for the first time, the innervation patterns of the area dorsal to the patellar tendon in man. It shows that the area investigated is under marked influence by the sympathetic nervous system. Thus, sympathetic effects are likely to occur for blood vessels of the area, which is interesting since color Doppler has revealed that vessels of this area ("neovessels") display a pathologically high blood flow in tendinosis. The findings are discussed in relation to aspects of vascular regulation, and to pain symptoms of tendinosis.

  • 205.
    Danielson, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Andersson, Gustav
    Alfredson, Håkan
    Forsgren, Sture
    Marked sympathetic component in the perivascular innervation of the dorsal paratendinous tissue targeted in sclerosing Polidocanol injection therapy of patellar tendinosisManuscript (Other academic)
  • 206.
    Danielson, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Scott, Alex
    Univ British Columbia, Dept Phys Therapy, Vancouver, BC V5Z 1M9, Canada.
    Teaming up to beat tendon pain: clinical and research excellence own the podium at ISTS (International Scientific Tendinopathy Symposium).2013In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 47, no 9, p. 532-532Article in journal (Refereed)
  • 207.
    Danielsson, Åke
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    Functional aspects of the exocrine pancreas in relation to the islets of Langerhans: effects of islet hormones on the synthesis, storage and secretion of amylase1974Doctoral thesis, comprehensive summary (Other academic)
  • 208. Dardevet, Dominique
    et al.
    Savary-Auzeloux, Isabelle
    Remond, Didier
    Mosoni, Laurent
    Marzetti, Emanuele
    Buford, Thomas W
    Bernabei, Roberto
    Dionne, Isabelle J
    Buford, Thomas W
    Marzetti, Emanuele
    Manini, Todd M
    Buehring, Bjoern
    Kirchner, Elizabeth
    Calabrese, Leonard
    Manini, Todd M
    Clark, Brian C
    Fonseca, Helder M
    Delbono, Osvaldo
    Taylor, Jackson R
    Aubertin-Leheudre, Mylène
    Barbat-Artigas, Sébastien
    Pion, Charlotte H
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Gustafsson, Thomas
    Cederholm, Tommy
    Ulfhake, Brun
    Commentaries on Viewpoint: muscle atrophy is not always sarcopenia.2012In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 113, no 4, p. 680-684Article in journal (Refereed)
  • 209. Daste, Frederic
    et al.
    Walrant, Astrid
    Holst, Mikkel R.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Gadsby, Jonathan R.
    Mason, Julia
    Lee, Ji-Eun
    Brook, Daniel
    Mettlen, Marcel
    Larsson, Elin
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Lee, Steven F.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Gallop, Jennifer L.
    Control of actin polymerization via the coincidence of phosphoinositides and high membrane curvature2017In: Journal of Cell Biology, ISSN 0021-9525, E-ISSN 1540-8140, Vol. 216, no 11, p. 3745-3765Article in journal (Refereed)
    Abstract [en]

    The conditional use of actin during clathrin-mediated endocytosis in mammalian cells suggests that the cell controls whether and how actin is used. Using a combination of biochemical reconstitution and mammalian cell culture, we elucidate a mechanism by which the coincidence of PI(4,5)P-2 and PI(3)P in a curved vesicle triggers actin polymerization. At clathrin-coated pits, PI(3) P is produced by the INPP4A hydrolysis of PI(3,4)P-2, and this is necessary for actin-driven endocytosis. Both Cdc42.guanosine triphosphate and SNX9 activate N-WASP-WIP-and Arp2/3-mediated actin nucleation. Membrane curvature, PI(4,5)P-2, and PI(3) P signals are needed for SNX9 assembly via its PX-BAR domain, whereas signaling through Cdc42 is activated by PI(4,5)P-2 alone. INPP4A activity is stimulated by high membrane curvature and synergizes with SNX9 BAR domain binding in a process we call curvature cascade amplification. We show that the SNX9-driven actin comets that arise on human disease-associated oculocerebrorenal syndrome of Lowe (OCRL) deficiencies are reduced by inhibiting PI(3) P production, suggesting PI(3) P kinase inhibitors as a therapeutic strategy in Lowe syndrome.

  • 210. Davies, G.
    et al.
    Armstrong, N.
    Bis, J. C.
    Bressler, J.
    Chouraki, V.
    Giddaluru, S.
    Hofer, E.
    Ibrahim-Verbaas, C. A.
    Kirin, M.
    Lahti, J.
    van der Lee, S. J.
    Le Hellard, S.
    Liu, T.
    Marioni, R. E.
    Oldmeadow, C.
    Postmus, I.
    Smith, A. V.
    Smith, J. A.
    Thalamuthu, A.
    Thomson, R.
    Vitart, V.
    Wang, J.
    Yu, L.
    Zgaga, L.
    Zhao, W.
    Boxall, R.
    Harris, S. E.
    Hill, W. D.
    Liewald, D. C.
    Luciano, M.
    Adams, H.
    Ames, D.
    Amin, N.
    Amouyel, P.
    Assareh, A. A.
    Au, R.
    Becker, J. T.
    Beiser, A.
    Berr, C.
    Bertram, L.
    Boerwinkle, E.
    Buckley, B. M.
    Campbell, H.
    Corley, J.
    De Jager, P. L.
    Dufouil, C.
    Eriksson, J. G.
    Espeseth, T.
    Faul, J. D.
    Ford, I.
    Gottesman, R. F.
    Griswold, M. E.
    Gudnason, V.
    Harris, T. B.
    Heiss, G.
    Hofman, A.
    Holliday, E. G.
    Huffman, J.
    Kardia, S. L. R.
    Kochan, N.
    Knopman, D. S.
    Kwok, J. B.
    Lambert, J-C
    Lee, T.
    Li, G.
    Li, S-C
    Loitfelder, M.
    Lopez, O. L.
    Lundervold, A. J.
    Lundquist, Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Mather, K. A.
    Mirza, S. S.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Oostra, B. A.
    Palotie, A.
    Papenberg, G.
    Pattie, A.
    Petrovic, K.
    Polasek, O.
    Psaty, B. M.
    Redmond, P.
    Reppermund, S.
    Rotter, J. I.
    Schmidt, H.
    Schuur, M.
    Schofield, P. W.
    Scott, R. J.
    Steen, V. M.
    Stott, D. J.
    Van Swieten, J. C.
    Taylor, K. D.
    Trollor, J.
    Trompet, S.
    Uitterlinden, A. G.
    Weinstein, G.
    Widen, E.
    Windham, B. G.
    Jukema, J. W.
    Wright, A. F.
    Wright, M. J.
    Yang, Q.
    Amieva, H.
    Attia, J. R.
    Bennett, D. A.
    Brodaty, H.
    de Craen, A. J. M.
    Hayward, C.
    Ikram, M. A.
    Lindenberger, U.
    Nilsson, Lars-Göran
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). ARC, Karolinska Institutet, Stockholm.
    Porteous, D. J.
    Raikkonen, K.
    Reinvang, I.
    Rudan, I.
    Sachdev, P. S.
    Schmidt, R.
    Schofield, P. R.
    Srikanth, V.
    Starr, J. M.
    Turner, S. T.
    Weir, D. R.
    Wilson, J. F.
    Van Duijn, C.
    Launer, L.
    Fitzpatrick, A. L.
    Seshadri, S.
    Jr, T. H. Mosley
    Deary, I. J.
    Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53 949)2015In: Molecular Psychiatry, ISSN 1359-4184, E-ISSN 1476-5578, Vol. 20, no 2, p. 183-192Article in journal (Refereed)
    Abstract [en]

    General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health-and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N = 53 949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P = 3.93 x 10(-9), MIR2113; rs17522122, P = 2.55 x 10(-8), AKAP6; rs10119, P = 5.67 x 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P = 1x10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N = 6617) and the Health and Retirement Study (N = 5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e. = 5%) and 28% (s.e. = 7%), respectively. Using polygenic prediction analysis, similar to 1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N = 5487; P = 1.5 x 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

  • 211. Davies, Gail
    et al.
    Lam, Max
    Harris, Sarah E.
    Trampush, Joey W.
    Luciano, Michelle
    Hill, W. David
    Hagenaars, Saskia P.
    Ritchie, Stuart J.
    Marioni, Riccardo E.
    Fawns-Ritchie, Chloe
    Liewald, David C. M.
    Okely, Judith A.
    Ahola-Olli, Ari V.
    Barnes, Catriona L. K.
    Bertram, Lars
    Bis, Joshua C.
    Burdick, Katherine E.
    Christoforou, Andrea
    DeRosse, Pamela
    Djurovic, Srdjan
    Espeseth, Thomas
    Giakoumaki, Stella
    Giddaluru, Sudheer
    Gustavson, Daniel E.
    Hayward, Caroline
    Hofer, Edith
    Ikram, M. Arfan
    Karlsson, Robert
    Knowles, Emma
    Lahti, Jari
    Leber, Markus
    Li, Shuo
    Mather, Karen A.
    Melle, Ingrid
    Morris, Derek
    Oldmeadow, Christopher
    Palviainen, Teemu
    Payton, Antony
    Pazoki, Raha
    Petrovic, Katja
    Reynolds, Chandra A.
    Sargurupremraj, Muralidharan
    Scholz, Markus
    Smith, Jennifer A.
    Smith, Albert V.
    Terzikhan, Natalie
    Thalamuthu, Anbupalam
    Trompet, Stella
    van der Lee, Sven J.
    Ware, Erin B.
    Windham, B. Gwen
    Wright, Margaret J.
    Yang, Jingyun
    Yu, Jin
    Ames, David
    Amin, Najaf
    Amouyel, Philippe
    Andreassen, Ole A.
    Armstrong, Nicola J.
    Assareh, Amelia A.
    Attia, John R.
    Attix, Deborah
    Avramopoulos, Dimitrios
    Bennett, David A.
    Boehmer, Anne C.
    Boyle, Patricia A.
    Brodaty, Henry
    Campbell, Harry
    Cannon, Tyrone D.
    Cirulli, Elizabeth T.
    Congdon, Eliza
    Conley, Emily Drabant
    Corley, Janie
    Cox, Simon R.
    Dale, Anders M.
    Dehghan, Abbas
    Dick, Danielle
    Dickinson, Dwight
    Eriksson, Johan G.
    Evangelou, Evangelos
    Faul, Jessica D.
    Ford, Ian
    Freimer, Nelson A.
    Gao, He
    Giegling, Ina
    Gillespie, Nathan A.
    Gordon, Scott D.
    Gottesman, Rebecca F.
    Griswold, Michael E.
    Gudnason, Vilmundur
    Harris, Tamara B.
    Hartmann, Annette M.
    Hatzimanolis, Alex
    Heiss, Gerardo
    Holliday, Elizabeth G.
    Joshi, Peter K.
    Kahonen, Mika
    Kardia, Sharon L. R.
    Karlsson, Ida
    Kleineidam, Luca
    Knopman, David S.
    Kochan, Nicole A.
    Konte, Bettina
    Kwok, John B.
    Le Hellard, Stephanie
    Lee, Teresa
    Lehtimaki, Terho
    Li, Shu-Chen
    Liu, Tian
    Koini, Marisa
    London, Edythe
    Longstreth, Will T., Jr.
    Lopez, Oscar L.
    Loukola, Anu
    Luck, Tobias
    Lundervold, Astri J.
    Lundquist, Anders
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Lyytikainen, Leo-Pekka
    Martin, Nicholas G.
    Montgomery, Grant W.
    Murray, Alison D.
    Need, Anna C.
    Noordam, Raymond
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Ollier, William
    Papenberg, Goran
    Pattie, Alison
    Polasek, Ozren
    Poldrack, Russell A.
    Psaty, Bruce M.
    Reppermund, Simone
    Riedel-Heller, Steffi G.
    Rose, Richard J.
    Rotter, Jerome I.
    Roussos, Panos
    Rovio, Suvi P.
    Saba, Yasaman
    Sabb, Fred W.
    Sachdev, Perminder S.
    Satizabal, Claudia L.
    Schmid, Matthias
    Scott, Rodney J.
    Scult, Matthew A.
    Simino, Jeannette
    Slagboom, P. Eline
    Smyrnis, Nikolaos
    Soumare, Aicha
    Stefanis, Nikos C.
    Stott, David J.
    Straub, Richard E.
    Sundet, Kjetil
    Taylor, Adele M.
    Taylor, Kent D.
    Tzoulaki, Ioanna
    Tzourio, Christophe
    Uitterlinden, Andre
    Vitart, Veronique
    Voineskos, Aristotle N.
    Kaprio, Jaakko
    Wagner, Michael
    Wagner, Holger
    Weinhold, Leonie
    Wen, K. Hoyan
    Widen, Elisabeth
    Yang, Qiong
    Zhao, Wei
    Adams, Hieab H. H.
    Arking, Dan E.
    Bilder, Robert M.
    Bitsios, Panos
    Boerwinkle, Eric
    Chiba-Falek, Ornit
    Corvin, Aiden
    De Jager, Philip L.
    Debette, Stephanie
    Donohoe, Gary
    Elliott, Paul
    Fitzpatrick, Annette L.
    Gill, Michael
    Glahn, David C.
    Hagg, Sara
    Hansell, Narelle K.
    Hariri, Ahmad R.
    Ikram, M. Kamran
    Jukema, J. Wouter
    Vuoksimaa, Eero
    Keller, Matthew C.
    Kremen, William S.
    Launer, Lenore
    Lindenberger, Ulman
    Palotie, Aarno
    Pedersen, Nancy L.
    Pendleton, Neil
    Porteous, David J.
    Raikkonen, Katri
    Raitakari, Olli T.
    Ramirez, Alfredo
    Reinvang, Ivar
    Rudan, Igor
    Rujescu, Dan
    Schmidt, Reinhold
    Schmidt, Helena
    Schofield, Peter W.
    Schofield, Peter R.
    Starr, John M.
    Steen, Vidar M.
    Trollor, Julian N.
    Turner, Steven T.
    Van Duijn, Cornelia M.
    Villringer, Arno
    Weinberger, Daniel R.
    Weir, David R.
    Wilson, James F.
    Malhotra, Anil
    McIntosh, Andrew M.
    Gale, Catharine R.
    Seshadri, Sudha
    Mosley, Thomas H., Jr.
    Bressler, Jan
    Lencz, Todd
    Deary, Ian J.
    Study of 300,486 individuals identifies 148 independent genetic loci influencing general cognitive function2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 2098Article in journal (Refereed)
    Abstract [en]

    General cognitive function is a prominent and relatively stable human trait that is associated with many important life outcomes. We combine cognitive and genetic data from the CHARGE and COGENT consortia, and UK Biobank (total N = 300,486; age 16-102) and find 148 genome-wide significant independent loci (P < 5 x 10-8) associated with general cognitive function. Within the novel genetic loci are variants associated with neurodegenerative and neurodevelopmental disorders, physical and psychiatric illnesses, and brain structure. Gene-based analyses find 709 genes associated with general cognitive function. Expression levels across the cortex are associated with general cognitive function. Using polygenic scores, up to 4.3% of variance in general cognitive function is predicted in independent samples. We detect significant genetic overlap between general cognitive function, reaction time, and many health variables including eyesight, hypertension, and longevity. In conclusion we identify novel genetic loci and pathways contributing to the heritability of general cognitive function.

  • 212. de Boer, Lieke
    et al.
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Chowdhury, Rumana
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Dolan, Raymond J.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Backman, Lars
    Guitart-Masip, Marc
    Dorsal striatal dopamine D1 receptor availability predicts an instrumental bias in action learning2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, no 1, p. 261-270Article in journal (Refereed)
    Abstract [en]

    Learning to act to obtain reward and inhibit to avoid punishment is easier compared with learning the opposite contingencies. This coupling of action and valence is often thought of as a Pavlovian bias, although recent research has shown it may also emerge through instrumental mechanisms. We measured this learning bias with a rewarded go/no-go task in 60 adults of different ages. Using computational modeling, we characterized the bias as being instrumental. To assess the role of endogenous dopamine (DA) in the expression of this bias, we quantified DA D1 receptor availability using positron emission tomography (PET) with the radioligand [11C]SCH23390. Using principal-component analysis on the binding potentials in a number of cortical and striatal regions of interest, we demonstrated that cortical, dorsal striatal, and ventral striatal areas provide independent sources of variance in DA D1 receptor availability. Interindividual variation in the dorsal striatal component was related to the strength of the instrumental bias during learning. These data suggest at least three anatomical sources of variance in DA D1 receptor availability separable using PET in humans, and we provide evidence that human dorsal striatal DA D1 receptors are involved in the modulation of instrumental learning biases.

  • 213. de Boer, Lieke
    et al.
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Dayan, Peter
    Backman, Lars
    Guitart-Masip, Marc
    Attenuation of dopamine-modulated prefrontal value signals underlies probabilistic reward learning deficits in old age2017In: eLIFE, E-ISSN 2050-084X, Vol. 6, article id e2642Article in journal (Refereed)
    Abstract [en]

    Probabilistic reward learning is characterised by individual differences that become acute in aging. This may be due to age-related dopamine (DA) decline affecting neural processing in striatum, prefrontal cortex, or both. We examined this by administering a probabilistic reward learning task to younger and older adults, and combining computational modelling of behaviour, fMRI and PET measurements of DA D1 availability. We found that anticipatory value signals in ventromedial prefrontal cortex (vmPFC) were attenuated in older adults. The strength of this signal predicted performance beyond age and was modulated by D1 availability in nucleus accumbens. These results uncover that a value-anticipation mechanism in vmPFC declines in aging, and that this mechanism is associated with DA D1 receptor availability.

  • 214.
    de Frias, Cindy M
    et al.
    Stockholm University.
    Marklund, Petter
    Stockholm University, Stockholm Brain Institute.
    Eriksson, Elias
    Göteborg University.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Öman, Lena
    Umeå University.
    Annerbrink, Kristina
    Göteborg University.
    Bäckman, Lars
    Karolinska Institute.
    Nilsson, Lars-Göran
    Stockholm University.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Influence of COMT gene polymorphism on fMRI-assessed sustained and transient activity during a working memory task.2010In: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 22, no 7, p. 1614-1622Article in journal (Refereed)
    Abstract [en]

    The catechol O-methyltransferase (COMT) gene--encoding an enzyme that is essential for the degradation of dopamine (DA) in prefrontal cortex (PFC)--contains a single nucleotide polymorphism (val/met) important for cognition. According to the tonic-phasic hypothesis, individuals carrying the low-enzyme-activity allele (met) are characterized by enhanced tonic DA activity in PFC, promoting sustained cognitive representations in working memory. Val carriers have reduced tonic but enhanced phasic dopaminergic activity in subcortical regions, enhancing cognitive flexibility. We tested the tonic-phasic DA hypothesis by dissociating sustained and transient brain activity during performance on a 2-back working memory test using mixed blocked/event-related functional magnetic resonance imaging. Participants were men recruited from a random sample of the population (the Betula study) and consisted of 11 met/met and 11 val/val carriers aged 50 to 65 years, matched on age, education, and cognitive performance. There were no differences in 2-back performance between genotype groups. Met carriers displayed a greater transient medial temporal lobe response in the updating phase of working memory, whereas val carriers showed a greater sustained PFC activation in the maintenance phase. These results support the tonic-phasic theory of DA function in elucidating the specific phenotypic influence of the COMT val(158)met polymorphism on different components of working memory.

  • 215.
    Degerman, Sofie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Josefsson, Maria
    Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Nordin Adolfsson, Annelie
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Psychiatry.
    Wennstedt, Sigrid
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Landfors, Mattias
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Haider, Zahra
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Pudas, Sara
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Hultdin, Magnus
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Adolfsson, Rolf
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Psychiatry.
    Maintained memory in aging is associated with young epigenetic age2017In: Neurobiology of Aging, ISSN 0197-4580, E-ISSN 1558-1497, Vol. 55, p. 167-171Article in journal (Refereed)
    Abstract [en]

    Epigenetic alterations during aging have been proposed to contribute to decline in physical and cognitive functions, and accelerated epigenetic aging has been associated with disease and all-cause mortality later in life. In this study, we estimated epigenetic age dynamics in groups with different memory trajectories (maintained high performance, average decline, and accelerated decline) over a 15-year period. Epigenetic (DNA-methylation [DNAm]) age was assessed, and delta age (DNAm age - chronological age) was calculated in blood samples at baseline (age: 55-65 years) and 15 years later in 52 age- and gender-matched individuals from the Betula study in Sweden. A lower delta DNAm age was observed for those with maintained memory functions compared with those with average (p = 0.035) or accelerated decline (p = 0.037). Moreover, separate analyses revealed that DNAm age at follow-up, but not chronologic age, was a significant predictor of dementia (p = 0.019). Our findings suggest that young epigenetic age contributes to maintained memory in aging.

  • 216. Delhaye, Benoit
    et al.
    Barrea, Allan
    Edin, Benoni B.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Lefèvre, Philippe
    Thonnard, Jean-Louis
    Surface strain measurements of fingertip skin under shearing2016In: Journal of the Royal Society Interface, ISSN 1742-5689, E-ISSN 1742-5662, Vol. 13, no 115, article id 20150874Article in journal (Refereed)
    Abstract [en]

    The temporal evolution of surface strain, resulting from a combination of normal and tangential loading forces on the fingerpad, was calculated from high-resolution images. A customized robotic device loaded the fingertip with varying normal force, tangential direction and tangential speed. We observed strain waves that propagated from the periphery to the centre of the contact area. Consequently, different regions of the contact area were subject to varying degrees of compression, stretch and shear. The spatial distribution of both the strains and the strain energy densities depended on the stimulus direction. Additionally, the strains varied with the normal force level and were substantial, e.g. peak strains of 50% with a normal force of 5 N, i.e. at force levels well within the range of common dexterous manipulation tasks. While these observations were consistent with some theoretical predictions from contact mechanics, we also observed substantial deviations as expected given the complex geometry and mechanics of fingertips. Specifically, from in-depth analyses, we conclude that some of these deviations depend on local fingerprint patterns. Our data provide useful information for models of tactile afferent responses and background for the design of novel haptic interfaces.

  • 217. Di, Guohu
    et al.
    Qi, Xia
    Zhao, Xiaowen
    Zhang, Songmei
    Danielson, Patrik
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Zhou, Qingjun
    Corneal Epithelium-Derived Neurotrophic Factors Promote Nerve Regeneration2017In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 58, no 11, p. 4695-4702Article in journal (Refereed)
    Abstract [en]

    PURPOSE. To explore the neurotrophic factor expression in corneal epithelium and evaluate their effects on the trigeminal ganglion (TG) neurite outgrowth and corneal nerve regeneration in mice. METHODS. The expression of neurotrophic factors was compared among the intact, regenerating, and regenerated mouse corneal epithelium. Mouse primary TG neurons were treated with the conditioned medium of mouse corneal epithelial cells. Nerve growth factor (NGF) neutralizing antibody and glial cell-derived neurotrophic factor (GDNF) neutralizing antibody were used to evaluate their roles in mouse corneal nerve regeneration and TG neurite outgrowth. The promoting effects of NGF and GDNF for the corneal nerve regeneration were further evaluated in the diabetic mice. RESULTS. The expression of NGF and GDNF showed significant up-regulation in regenerating corneal epithelium and return to the preinjury levels in the regenerated epithelium, which was consistent with the progress of corneal subbasal nerve regeneration. The conditioned medium of corneal epithelial cells promoted the TG neurite outgrowth with extended branching and elongation. Furthermore, the blockage of either NGF or GDNF significantly impaired the promotion of the neurite outgrowth by the conditioned medium or the corneal nerve regeneration in normal mice. Moreover, the expression of NGF and GDNF was attenuated in the diabetic regenerating corneal epithelium as compared to that in normal mice, while exogenous NGF or GDNF supplement promoted the corneal epithelial and nerve regeneration in diabetic mice. CONCLUSIONS. Corneal epithelium expresses multiple neurotrophic factors, among which NGF and GDNF may play an important role in the corneal nerve regeneration.

  • 218.
    di Summa, Pietro G
    et al.
    University Hospital of Lausanne, University of Manchester.
    Kalbermatten, Daniel F
    University Hospital of Lausanne, University Hospital of Basel.
    Pralong, E
    University Hospital of Lausanne.
    Raffoul, W
    University Hospital of Lausanne.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Terenghi, Giorgio
    University of Manchester.
    Long-term in vivo regeneration of peripheral nerves through bioengineered nerve grafts2011In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 181, no 5, p. 278-291Article in journal (Refereed)
    Abstract [en]

    Although autologous nerve graft is still the first choice strategy in nerve reconstruction, it has the severe disadvantage of the sacrifice of a functional nerve. Cell transplantation in a bioartificial conduit is an alternative strategy to improve nerve regeneration. Nerve fibrin conduits were seeded with various cell types: primary Schwann cells (SC), SC-like differentiated bone marrow-derived mesenchymal stem cells (dMSC), SC-like differentiated adipose-derived stem cells (dASC). Two further control groups were fibrin conduits without cells and autografts. Conduits were used to bridge a 1 cm rat sciatic nerve gap in a long term experiment (16 weeks). Functional and morphological properties of regenerated nerves were investigated. A reduction in muscle atrophy was observed in the autograft and in all cell-seeded groups, when compared with the empty fibrin conduits. SC showed significant improvement in axon myelination and average fiber diameter of the regenerated nerves. dASC were the most effective cell population in terms of improvement of axonal and fiber diameter, evoked potentials at the level of the gastrocnemius muscle and regeneration of motoneurons, similar to the autografts. Given these results and other advantages of adipose derived stem cells such as ease of harvest and relative abundance, dASC could be a clinically translatable route towards new methods to enhance peripheral nerve repair.

  • 219.
    di Summa, Pietro G
    et al.
    University of Manchester, University Hospital of Lausanne.
    Kalbermatten, Daniel F
    University Hospital of Basel.
    Raffoul, Wassim
    University Hospital of Lausanne.
    Terenghi, Giorgio
    University of Manchester.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. University of Manchester.
    Extracellular matrix molecules enhance the neurotrophic effect of Schwann cell-like differentiated adipose-derived stem cells and increase cell survival under stress conditions2013In: Tissue Engineering. Part A, ISSN 1937-3341, E-ISSN 1937-335X, Vol. 19, no 3-4, p. 368-379Article in journal (Refereed)
    Abstract [en]

    Since the first reports of induction of adipose-derived stem cells (ASC) into neuronal and glial cell phenotypes, expectations have increased regarding their use in tissue engineering applications for nerve repair. Cell adhesion to extracellular matrix (ECM) is a basic feature of survival, differentiation, and migration of Schwann cells (SC) during nerve regeneration, and fibronectin and laminin are two key molecules of this process. Interaction between ECM and SC-like differentiated ASC (dASC) could potentially improve the neurotrophic potential of the stem cells. We have investigated the effect of ECM molecules on SC-like dASC in terms of proliferation, adhesion, and cell viability. Fibronectin and laminin did not affect the proliferation of dASC when compared with cell adherent tissue culture plastic, but significantly improved viability and cell attachment when dASC were exposed to apoptotic conditions. To assess the influence of the ECM molecules on dASC neurotrophic activity, dASC were seeded onto ECM-coated culture inserts suspended above dorsal root ganglia (DRG) sensory neurons. Neurite outgrowth of DRG neurons was enhanced when dASC were seeded on fibronectin and laminin when compared with controls. When DRG neurons and dASC were in direct contact on the various surfaces there was significantly enhanced neurite outgrowth and coculture with laminin-conditioned dASC produced the longest neurites. Compared with primary SCs, dASC grown on laminin produced similar levels of neurite outgrowth in the culture insert experiments but neurite length was shorter in the direct contact groups. Anti beta 1 integrin blocking antibody could inhibit baseline and dASC evoked neurite elongation but had no effect on outgrowth mediated by laminin-conditioned dASC. ECM molecules had no effect on the levels of nerve growth factor and brain-derived neurotrophic factor secretion from dASC. The results of the study suggest that ECM molecules can significantly improve the potential of dASC for nerve regeneration.

  • 220.
    di Summa, Pietro G.
    et al.
    Department of Plastic, Reconstructive Surgery, University Hospital of Lausanne (CHUV), Rue du Bugnon 46, 1011 Lausanne, Switzerland. Electronic address: Pietro.Di-Summa@chuv.ch..
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Campisi, Corrado C.
    Department of Plastic, Reconstructive Surgery, University Hospital of Genova, Ospedale S. Martino, Largo Rossana Benzi 10, 16132 Genova, Italy.
    Raffoul, Wassim
    Department of Plastic, Reconstructive Surgery, University Hospital of Lausanne (CHUV), Rue du Bugnon 46, 1011 Lausanne, Switzerland.
    Kalbermatten, Daniel F.
    Department of Plastic, Reconstructive Surgery, University Hospital of Basel, Spitalstrasse 21, CH-4031 Basel, Switzerland.
    Collagen (NeuraGen(®)) nerve conduits and stem cells for peripheral nerve gap repair2014In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 572, p. 26-31Article in journal (Refereed)
    Abstract [en]

    Collagen nerve guides are used clinically for peripheral nerve defects, but their use is generally limited to lesions up to 3cm. In this study we combined collagen conduits with cells as an alternative strategy to support nerve regeneration over longer gaps. In vitro cell adherence to collagen conduits (NeuraGen(®) nerve guides) was assessed by scanning electron microscopy. For in vivo experiments, conduits were seeded with either Schwann cells (SC), SC-like differentiated bone marrow-derived mesenchymal stem cells (dMSC), SC-like differentiated adipose-derived stem cells (dASC) or left empty (control group), conduits were used to bridge a 1cm gap in the rat sciatic nerve and after 2-weeks immunohistochemical analysis was performed to assess axonal regeneration and SC infiltration. The regenerative cells showed good adherence to the collagen walls. Primary SC showed significant improvement in distal stump sprouting. No significant differences in proximal regeneration distances were noticed among experimental groups. dMSC and dASC-loaded conduits showed a diffuse sprouting pattern, while SC-loaded showed an enhanced cone pattern and a typical sprouting along the conduits walls, suggesting an increased affinity for the collagen type I fibrillar structure. NeuraGen(®) guides showed high affinity of regenerative cells and could be used as efficient vehicle for cell delivery. However, surface modifications (e.g. with extracellular matrix molecule peptides) of NeuraGen(®) guides could be used in future tissue-engineering applications to better exploit the cell potential.

  • 221.
    di Summa, Pietro G
    et al.
    Chirurgie Plastique et Reconstructive CHUV, Université de Lausanne, Rue de Bugnon 46, 1005 Lausanne, CH, Switzerland.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Raffoul, W
    Chirurgie Plastique et Reconstructive CHUV, Université de Lausanne, Rue de Bugnon 46, 1005 Lausanne, CH, Switzerland.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Terenghi, Giorgio
    Blond McIndoe Research Laboratories. The University of Manchester, Manchester, UK.
    Kalbermatten, Daniel F
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Adipose-derived stem cells enhance peripheral nerve regeneration2010In: Journal of plastic, reconstructive and aesthetic surgery, ISSN 1878-0539, Vol. 63, no 9, p. 1544-1552Article in journal (Refereed)
    Abstract [en]

    Traumatic injuries resulting in peripheral nerve lesions often require a graft to bridge the gap. Although autologous nerve auto-graft is still the first-choice strategy in reconstructions, it has the severe disadvantage of the sacrifice of a functional nerve. Cell transplantation in a bioartificial conduit is an alternative strategy to create a favourable environment for nerve regeneration. We decided to test new fibrin nerve conduits seeded with various cell types (primary Schwann cells and adult stem cells differentiated to a Schwann cell-like phenotype) for repair of sciatic nerve injury. Two weeks after implantation, the conduits were removed and examined by immunohistochemistry for axonal regeneration (evaluated by PGP 9.5 expression) and Schwann cell presence (detected by S100 expression). The results show a significant increase in axonal regeneration in the group of fibrin seeded with Schwann cells compared with the empty fibrin conduit. Differentiated adipose-derived stem cells also enhanced regeneration distance in a similar manner to differentiated bone marrow mesenchymal stem cells. These observations suggest that adipose-derived stem cells may provide an effective cell population, without the limitations of the donor-site morbidity associated with isolation of Schwann cells, and could be a clinically translatable route towards new methods to enhance peripheral nerve repair.

  • 222. Diamond, Jonathan S.
    et al.
    Nashed, Joseph Y.
    Johansson, Roland S.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Wolpert, Daniel M.
    Flanagan, J. Randall
    Rapid Visuomotor Corrective Responses during Transport of Hand-Held Objects Incorporate Novel Object Dynamics2015In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 35, no 29, p. 10572-10580Article in journal (Refereed)
    Abstract [en]

    Numerous studies have shown that people are adept at learning novel object dynamics, linking applied force and motion, when performing reaching movements with hand-held objects. Here we investigated whether the control of rapid corrective arm responses, elicited in response to visual perturbations, has access to such newly acquired knowledge of object dynamics. Participants first learned to make reaching movements while grasping an object subjected to complex load forces that depended on the distance and angle of the hand from the start position. During a subsequent test phase, we examined grip and load force coordination during corrective arm movements elicited (within similar to 150 ms) in response to viewed sudden lateral shifts (1.5 cm) in target or object position. We hypothesized that, if knowledge of object dynamics is incorporated in the control of the corrective responses, grip force changes would anticipate the unusual load force changes associated with the corrective arm movements so as to support grasp stability. Indeed, we found that the participants generated grip force adjustments tightly coupled, both spatially and temporally, to the load force changes associated with the arm movement corrections. We submit that recently learned novel object dynamics are effectively integrated into sensorimotor control policies that support rapid visually driven arm corrective actions during transport of hand held objects.

  • 223.
    Dimitriou, M
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Discharges in Human Muscle Receptor Afferents during Block Grasping2008In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 28, no 48, p. 12632-12642Article in journal (Refereed)
  • 224.
    Dimitriou, M
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Discharges in human muscle spindle afferents during a key-pressing task2008In: The Journal of General Physiology, ISSN 0022-1295, E-ISSN 1540-7748, Vol. 586, no 22, p. 5455-5470Article in journal (Refereed)
  • 225.
    Dimitriou, M
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Edin, Benoni B
    Human muscle spindles act as forward sensory models.Manuscript (Other academic)
  • 226.
    Dimitriou, Michael
    Umeå University, Faculty of Medicine, Integrative Medical Biology.
    Discharges in human muscle afferents during manual tasks2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Muscle spindles are complex sensory organs that have been strongly implicated in the control and perception of movements. Human muscle spindles in relaxed muscles behave as stretch receptors, responding to the length and velocity of their parent muscles. However, it has been unclear how they discharge during active movements since their discharges are also affected by fusimotor activity and extrafusal contractions. The vast majority of neurophysiological recordings of muscle afferents have been obtained under passive conditions, or active but behaviourally restricted conditions. These restrictions prevent predictions of human muscle afferent activity during purposeful multi-joint movements, naturally occurring during tasks such as hand shaping, grasping or key-pressing.

    An experimental protocol was therefore developed which allowed recordings of muscle receptor afferent activity using microneurography during unrestrained wrist and digit movements. Along with single afferent discharges, recordings were obtained of electromyographic activity of major forearm muscles and the kinematics of the wrist and digits. This approach allowed investigations of the factors shaping afferent discharge during everyday manual tasks, i.e., block-grasping and pressing sequences of keys, and during active sinusoidal joint movements. The afferents’ ability to encode information concerning the state of the muscle and joint kinematics during these tasks was also assessed.

    The responses of spindle afferents from load-bearing muscles were approximatelly 90 degrees more phase-advanced than expected on the length of their parent muscles. That is, the discharges of primary muscle spindle afferents were significantly affected by both velocity and acceleration, the discharges of secondary afferents by velocity, and neither afferent type was particularly affected by static muscle length. Accordingly, these afferents failed to encode length, encoded velocity well and acceleration poorly. The representation of muscle length and velocity was, however, significantly improved when the discharge activity of Golgi tendon afferents was taken into consideration along with muscle spindle activity. The discharge of primary afferents during both key-pressing and block-grasping was best correlated to the muscle velocities observed ~100-160 ms in the future. This predictive ability went beyond what could be expected from the spindles’ simultaneous sensitivity to velocity and acceleration, and could thus only be explained by implicating the fusimotor drive. In addition, evidence is presented that the fusimotor control of spindles was contingent on entire movement sequences during the key-pressing task.

    It is proposed that the phase relationship between the discharge rate of spindle afferents and the length of their parent muscles is load dependent. Moreover, muscle spindles seem to act as forward sensory models of their parent muscle, which makes sensorial feedback control possible despite neural delays.

  • 227.
    Dimitriou, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Enhanced Muscle Afferent Signals during Motor Learning in Humans2016In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 26, no 8, p. 1062-1068Article in journal (Refereed)
    Abstract [en]

    Much has been revealed concerning human motor learning at the behavioral level [1, 2], but less is known about changes in the involved neural circuits and signals. By examining muscle spindle responses during a classic visuomotor adaptation task [3-6] performed by fully alert humans, I found substantial modulation of sensory afferent signals as a function of adaptation state. Specifically, spindle control was independent of concurrent muscle activity but was specific to movement direction (representing muscle lengthening versus shortening) and to different stages of learning. Increased spindle afferent responses to muscle stretch occurring early during learning reflected individual error size and were negatively related to subsequent antagonist activity (i.e., 60-80 ms thereafter). Relative increases in tonic afferent output early during learning were predictive of the subjects' adaptation rate. I also found that independent spindle control during sensory realignment (the "washout" stage) induced afferent signal "linearization" with respect to muscle length (i.e., signals were more tuned to hand position). The results demonstrate for the first time that motor learning also involves independent and state-related modulation of sensory mechanoreceptor signals. The current findings suggest that adaptive motor performance also relies on the independent control of sensors, not just of muscles. I propose that the "gamma" motor system innervating spindles acts to facilitate the acquisition and extraction of task-relevant information at the early stages of sensorimotor adaptation. This designates a more active and targeted role for the human proprioceptive system during motor learning.

  • 228.
    Dimitriou, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Human Muscle Spindle Sensitivity Reflects the Balance of Activity between Antagonistic Muscles2014In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 34, no 41, p. 13644-13655Article in journal (Refereed)
    Abstract [en]

    Muscle spindles are commonly considered as stretch receptors encoding movement, but the functional consequence of their efferent control has remained unclear. The "alpha-gamma coactivation" hypothesis states that activity in a muscle is positively related to the output of its spindle afferents. However, in addition to the above, possible reciprocal inhibition of spindle controllers entails a negative relationship between contractile activity in one muscle and spindle afferent output from its antagonist. By recording spindle afferent responses from alert humans using microneurography, I show that spindle output does reflect antagonistic muscle balance. Specifically, regardless of identical kinematic profiles across active finger movements, stretch of the loaded antagonist muscle (i.e., extensor) was accompanied by increased afferent firing rates from this muscle compared with the baseline case of no constant external load. In contrast, spindle firing rates from the stretching antagonist were lowest when the agonist muscle powering movement (i.e., flexor) acted against an additional resistive load. Stepwise regressions confirmed that instantaneous velocity, extensor, and flexor muscle activity had a significant effect on spindle afferent responses, with flexor activity having a negative effect. Therefore, the results indicate that, as consequence of their efferent control, spindle sensitivity (gain) to muscle stretch reflects the balance of activity between antagonistic muscles rather than only the activity of the spindle-bearing muscle.

  • 229.
    Dimitriou, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Task-Dependent Modulation of Spinal and Transcortical Stretch Reflexes Linked to Motor Learning Rate2018In: Behavioral Neuroscience, ISSN 0735-7044, E-ISSN 1939-0084, Vol. 132, no 3, p. 194-209Article in journal (Refereed)
    Abstract [en]

    It is generally believed that task-dependent control of body configuration ("posture") is achieved by adjusting voluntary motor activity and transcortical "long-latency" reflexes. Spinal monosynaptic circuits are thought not to be engaged in such task-level control. Similarly, being in a state of motor learning has been strongly associated only with an upregulation of feedback responses at transcortical latencies and beyond. In two separate experiments, the current study examined the task-dependent modulation of stretch reflexes by perturbing the hand of human subjects while they were waiting for a "Go" signal to move at the different stages of a classic kinematic learning task (visuomotor rotation). Although the subjects had to resist all haptic perturbations equally across task stages, the study leveraged that task-dependent feedback controllers may already be "loaded" at the movement anticipation stage. In addition to an upregulation of reflex gains during early exposure to the visual distortion, I found a relative inhibition of reflex responses in the "washout" stage (sensory realignment state). For more distal muscles (brachioradialis) this inhibition also extended to the monosynaptic reflex response ("R1"). Moreover, these R1 gains reflected individual motor learning performance in the visuomotor task. The results demonstrate that the system's "control policy" in visuomotor adaptation can also include inhibition of proprioceptive reflexes, and that aspects of this policy can affect monosynaptic spinal circuits. The latter finding suggests a novel form of state-related control, probably realized by independent control of fusimotor neurons, through which segmental circuits can tune to higher-level features of a sensorimotor task.

  • 230.
    Dimitriou, Michael
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Human muscle spindles act as forward sensory models2010In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 20, no 19, p. 1763-1767Article in journal (Refereed)
    Abstract [en]

    Modern theories of motor control incorporate forward models that combine sensory information and motor commands to predict future sensory states. Such models circumvent unavoidable neural delays associated with on-line feedback control. Here we show that signals in human muscle spindle afferents during unconstrained wrist and finger movements predict future kinematic states of their parent muscle. Specifically, we show that the discharges of type Ia afferents are best correlated with the velocity of length changes in their parent muscles approximately 100-160 ms in the future and that their discharges vary depending on motor sequences in a way that cannot be explained by the state of their parent muscle alone. We therefore conclude that muscle spindles can act as "forward sensory models": they are affected both by the current state of their parent muscle and by efferent (fusimotor) control, and their discharges represent future kinematic states. If this conjecture is correct, then sensorimotor learning implies learning how to control not only the skeletal muscles but also the fusimotor system.

  • 231. Dinarello, Charles
    et al.
    Arend, William
    Sims, John
    Smith, Dirk
    Blumberg, Hal
    O'Neill, Luke
    Goldbach-Mansky, Raphaela
    Pizarro, Theresa
    Hoffman, H.
    Bufler, Philip
    Nold, Marcel
    Ghezzi, Pietro
    Mantovani, Alberto
    Garlanda, Cecilia
    Boraschi, Diana
    Rubartelli, Anna
    Netea, Mihai
    van der Meer, Jos
    Joosten, Leo
    Mandrup-Poulsen, Tom
    Donath, Marc
    Lewis, Eli
    Pfeilschifter, Josef
    Martin, Michael
    Kracht, Michael
    Muehl, H
    Novick, Daniela
    Lukic, Miodrag
    Conti, Bruno
    Solinger, Alan
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Odontology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    van de Veerdonk, Frank
    Gabel, Chiristopher
    IL-1 family nomenclature2010In: Nature Immunology, ISSN 1529-2908, E-ISSN 1529-2916, Vol. 11, no 11, p. 973-973Article in journal (Refereed)
  • 232.
    Domeij, Siw
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    The laryngeal mucosa and the superior laryngeal nerve of the rat: an immunohistochemical and electron microscopic study1990Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Neuropeptides are present in nerve fibers of the upper and lower airways. Local release of these substances may be of importance for the pathophysiology of airway disorders and may play a role in responses to different stimuli. However, little is known about the distribution of neuropeptides in the larynx. The superior laryngeal nerve is one of the vagal branches supplying the larynx. The aim of the present study was to investigate the fiber composition of this nerve and to analyse the distribution of different neuropeptides and mast cells in the larynx.

    The internal and the external branches of the superior laryngeal nerve had a similar number and size of the nerve fibers. Numerous unmyelinated fibers were evenly distributed in the branches. A large majority of the fibers were sensory myelinated and unmyelinated fibers; only a few of the myelinated fibers of the external branch ( 2-10 %) were motor. About a quarter of the unmyelinated fibers of the internal and the external branches had their cell bodies in the brainstem, and single myelinated and unmyelinated fibers emanated from the superior cervical ganglion. In every superior laryngeal nerve examined one to three spherical paraganglia were observed. These paraganglia contained cells which were similar to the type I and type II cells found in the carotid body and the paraganglia of the recurrent laryngeal nerve. Thin-walled sinusoidal blood vessels which were sometimes fenestrated were also present

    The laryngeal mucosa was supplied with nerve fibers exhibiting substance P- and calcitonin gene-related peptide-like immunoreactivity with regional differences in the distribution. The laryngeal side of the epiglottis and the ventral recess were richly supplied, and the vocal cords showed no evidence of immunoreactive nerve fibers. The distribution of connective tissue mast cells and mucosal mast cells/globular leucocytes was similar to that of nerve fibers displaying substance P- and calcitonin gene-related peptide-like immunoreactivity. These cells were found in close approximation to nerve fibers.

    Acetylcholinesterase-positive ganglionic cells in the larynx showed vasoactive intestinal polypeptide-, neuropeptide Y-and enkephalin-like immunoreactivity. Neuropeptide Y-like immunoreactivity was co-localized with tyrosine-hydroxylase/dopamine beta-hydroxylase-like immunoreactivity in nerve fibers in some blood vessel walls. Enkephalin-like immunoreactivity was rarely found in this location and co-localization with tyrosine- hydroxylase-like immunoreactivity was not detected. In glands and some blood vessel walls neuropeptide Y- and enkephalin-like immunoreactivity were localized in nerve fibers showing a positive acetylcholinesterase reaction and vasoactive intestinal polypeptide-like immunoreactivity. Thus, this indicates that neuropeptide Y is present in both the sympathetic and parasympathetic nervous systems, while enkephalin and vasoactive intestinal polypeptide are confined to the parasympathetic nervous system in the rat larynx.

    The present study shows that the superior laryngeal nerve is mainly sensory, and the study also provides a morphological basis for neuropeptide effects in laryngeal physiology/pathophysiology.

  • 233.
    Domellöf, Fatima Pedrosa
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Parkkonen, Kimmo
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Lindström, Mona
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nord, Hanna
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    von Hoffsten, Jonas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Li, Zhenlin
    Univ Paris 06, CNRS, INSERM, Inst Biol Paris Seine, Paris, France.
    Desmin in extraocular muscles2015In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, no 7Article in journal (Other academic)
  • 234.
    Domellöf, Fatima Pedrosa
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Rodriguez Garcia, Maria Angels
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Vicente, André
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Sandgren Hochhard, Karin
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Sarcomere remodelling and gene expression profile changes following strabismus surgery2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal (Other academic)
    Abstract [en]

    Purpose : To investigate the extent and time axis of sarcomere remodeling and of gene expression profile changes following resection surgery in an animal model of strabismus surgery.

    Methods : The right superior rectus (SR) of 16 adult New Zealand white rabbits was resected 4 mm and reattached to the sclera, with ethical permission and following the animal care directives. The superior rectus muscle of 4 rabbits was collected 1, 2, 4 and 6 weeks after surgery. The SR of 4 control rabbits was also collected. The muscles were divided into two pieces longitudinally and one half was directly frozen for RNA extraction and the other half was stretched, fixed in 2% paraformaldehyde and frozen after sucrose cryoprotection. Serial longitudinal sections were processed for immunohistochemistry with antibodies against desmin. For each muscle section, the area comprising exclusively longitudinally sectioned myofibers was evaluated and the number of dividing sarcomeres present within that area was determined. RNA sequencing was performed with Illumina HiSeq 2500.

    Results : One week after surgery, the number of sarcomere divisions was 86.5/mm2 (range 30.9-152.7), after two weeks 72.0/ mm2 (42.5-95.9), after 4 weeks 95.7/ mm2 (37.4-161.3). After 6 weeks the number of sarcomere divisions (26.8/ mm2, 9.2-60.7) was similar to that of the control samples (26.0/ mm2, 6.0-66.9). RNA sequencing revealed up to 198 differentially expressed genes and further bioinformatics analysis is ongoing. Preliminary data indicate that the most significantly altered biological processes are those involved in extracellular matrix organization and inflammation, along with regulation of response and production of growth factors involved in muscle repair and regeneration.

    Conclusions : Signs of sarcomerogenesis were present during the first 4 weeks after resection of the superior rectus, suggesting that sarcomerogenesis plays a role in surgical failure due to recovery of muscle length. We suggest that medical approaches to limit this mechanism may be a desirable complementary therapy to strabismus surgery in the future.

  • 235.
    Domellöf, Magdalena E
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Ekman, Urban
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Elgh, Eva
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Geriatric Medicine.
    Cognitive function in the early phase of Parkinson's disease, a five-year follow-up2015In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 132, no 2, p. 79-88Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Presence of mild cognitive impairment (MCI) as a predictor for Parkinson's disease dementia (PDD) has been discussed from a clinical perspective. Recently, a Movement Disorder Society (MDS) commissioned Task Force published guidelines for PD-MCI. However, long-term follow-ups of the PD-MCI guidelines for the prediction of PDD have been sparse.

    METHOD: In a community-based cohort of PD, the MDS guidelines for PD-MCI and consensus criteria for PDD were applied on 147 subjects. The predictive ability of PD-MCI for PDD was investigated. Additionally, baseline comparisons were conducted between MCI that converted to PDD and those who did not, and evolvement of motor function was investigated.

    RESULTS: One fourth of the population developed PDD. MCI and age at baseline predicted later occurrence of PDD, and baseline results of tests measuring episodic memory, visuospatial function, semantic fluency, and mental flexibility differed between MCI converters and non-converters. Postural instability/gait (PIGD) phenotype and education did not predict later occurrence of PDD, but increased postural/gait disturbances were shown across time in those developing dementia.

    CONCLUSION: The new PD-MCI guidelines are useful to detect patients at risk for developing PDD. The PIGD phenotype at diagnosis was not a predictor of PDD within 5 years, but the study supports a temporal association between postural/gait disturbances and PDD. Older patients with PD-MCI at baseline with decline in episodic memory, semantic fluency, and mental flexibility need to be carefully monitored regarding cognition and likely also for fall risk.

  • 236.
    Domellöf, Magdalena
    et al.
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
    Forsgren, Lars
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Ekman, Urban
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Elgh, Eva
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Geriatric Medicine.
    Cognitive function in the early phase of Parkinson's disease, a longitudinal follow-upManuscript (preprint) (Other academic)
  • 237.
    Dongre, Mitesh
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Singh, Bhupender
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Aung, Kyaw Min
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Larsson, Per
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Miftakhova, Regina R.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Persson, Karina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Askarian, Fatemeh
    Johannessen, Mona
    von Hofsten, Jonas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Persson, Jenny L.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Erhardt, Marc
    Tuck, Simon
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Flagella-mediated secretion of a novel Vibrio cholerae cytotoxin affecting both vertebrate and invertebrate hosts2018In: Communications Biology, ISSN 2399-3642, Vol. 1, article id 59Article in journal (Refereed)
    Abstract [en]

    Using Caenorhabditis elegans as an infection host model for Vibrio cholerae predator interactions, we discovered a bacterial cytotoxin, MakA, whose function as a virulence factor relies on secretion via the flagellum channel in a proton motive force-dependent manner. The MakA protein is expressed from the polycistronic makDCBA (motility-associated killing factor) operon. Bacteria expressing makDCBA induced dramatic changes in intestinal morphology leading to a defecation defect, starvation and death in C. elegans. The Mak proteins also promoted V. cholerae colonization of the zebrafish gut causing lethal infection. A structural model of purified MakA at 1.9 Å resolution indicated similarities to members of a superfamily of bacterial toxins with unknown biological roles. Our findings reveal an unrecognized role for V. cholerae flagella in cytotoxin export that may contribute both to environmental spread of the bacteria by promoting survival and proliferation in encounters with predators, and to pathophysiological effects during infections.

  • 238.
    Druzin, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Setting neuronal chloride gradient: a new role for extracellular matrix2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 215, p. 45-45Article in journal (Other academic)
  • 239.
    Druzin, Michael
    et al.
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Haage, David
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Johansson, Staffan
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Bicuculline free base blocks voltage-activated K+ currents in rat medial preoptic neurons.2004In: Neuropharmacology, ISSN 0028-3908, Vol. 46, no 2, p. 285-95Article in journal (Refereed)
    Abstract [en]

    The effects of the well-known GABA(A)-receptor blocker bicuculline on voltage-gated K(+) currents were studied in neurons from the medial preoptic nucleus (MPN) of rat. Whole-cell currents were recorded using the perforated-patch technique. Voltage steps from -54 to +6 mV resulted in tetraethylammonium-sensitive K(+) currents of delayed rectifier type. The total K(+) current (at 300 ms), including Ca(2+)-dependent and Ca(2+)-independent components, was reversibly reduced (17 +/- 4%) by 100 microM bicuculline methiodide and (37 +/- 5%) by 100 microM bicuculline as free base. The Ca(2+)-independent fraction (77 +/- 2%) of K(+) current evoked by a voltage step was, however, reduced (54 +/- 6%) only by bicuculline free base, but was not affected by bicuculline methiodide. The half-saturating concentration of bicuculline free base for blocking this purely voltage-gated K(+) current was 113 microM, whereas for blocking a steady Ca(2+)-dependent K(+) current it was 36 microM. The bicuculline-sensitive voltage-gated K(+) current was composed of 4-AP-sensitive and 4-AP-resistant components with different kinetic properties. No component of the purely voltage-gated K(+) current was affected neither by 100 nM alpha-dendrotoxin nor by 100 nM I-dendrotoxin. The possible K(+)-channel subtypes mediating the bicuculline-sensitive current in MPN neurons are discussed.

  • 240.
    Druzin, Michael
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Haage, David
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Malinina, Evgenya
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Staffan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Dual and opposing roles of presynaptic Ca2+ influx for spontaneous GABA release from rat medial preoptic nerve terminals.2002In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 542, no Pt 1, p. 131-46Article in journal (Refereed)
    Abstract [en]

    Calcium influx into the presynaptic nerve terminal is well established as a trigger signal for transmitter release by exocytosis. By studying dissociated preoptic neurons with functional adhering nerve terminals, we here show that presynaptic Ca2+ influx plays dual and opposing roles in the control of spontaneous transmitter release. Thus, application of various Ca2+ channel blockers paradoxically increased the frequency of spontaneous (miniature) inhibitory GABA-mediated postsynaptic currents (mIPSCs). Similar effects on mIPSC frequency were recorded upon washout of Cd2+ or EGTA from the external solution. The results are explained by a model with parallel Ca2+ influx through channels coupled to the exocytotic machinery and through channels coupled to Ca2+-activated K+ channels at a distance from the release site.

  • 241.
    Druzin, Michael
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Johansson, Staffan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    2-aminoethyl diphenylborinate blocks GABAA-receptor-mediated currents in rat medial preoptic neurons2016In: Opera Medica Et Physiologica, ISSN 2500-2295, Vol. 2, no 1, p. 63-68Article in journal (Refereed)
    Abstract [en]

    The effect of 2-aminoethyl diphenylborinate (2-APB), a commonly used drug to modulate inositol-1,4,5-triphosphate (IP3) receptors and transient receptor potential (TRP) channels, on GABAA receptor-mediatedcurrents was studied in neurons from the medial preoptic nucleus (MPN) of rat. 2-APB gradually and reversibly reducedthe currents evoked by GABA but had no effect on the currents evoked by glycine. The blocking effect was not mediatedby alterations in intracellular calcium concentration and showed a concentration dependence with half maximal effect at~50 μM 2-APB, for currents evoked by 100 μM, as well as by 1.0 mM GABA, suggesting that 2-APB is not competing withGABA for its binding site at the GABAA receptor. Thus, the present study describes a novel pharmacological property of2-APB as a non-competitive blocker of GABAA receptors and calls for caution in the interpretation of the results where2-APB is used to affect IP3 receptors or TRP channels.

  • 242.
    Druzin, Michael
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Malinina, Evgenya
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Grimsholm, Ola
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Staffan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Mechanism of estradiol-induced block of voltage-gated K+ currents in rat medial preoptic neurons.2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 5, p. e20213-Article in journal (Refereed)
    Abstract [en]

    The present study was conducted to characterize possible rapid effects of 17-β-estradiol on voltage-gated K(+) channels in preoptic neurons and, in particular, to identify the mechanisms by which 17-β-estradiol affects the K(+) channels. Whole-cell currents from dissociated rat preoptic neurons were studied by perforated-patch recording. 17-β-Estradiol rapidly (within seconds) and reversibly reduced the K(+) currents, showing an EC(50) value of 9.7 µM. The effect was slightly voltage dependent, but independent of external Ca(2+), and not sensitive to an estrogen-receptor blocker. Although 17-α-estradiol also significantly reduced the K(+) currents, membrane-impermeant forms of estradiol did not reduce the K(+) currents and other estrogens, testosterone and cholesterol were considerably less effective. The reduction induced by estradiol was overlapping with that of the K(V)-2-channel blocker r-stromatoxin-1. The time course of K(+) current in 17-β-estradiol, with a time-dependent inhibition and a slight dependence on external K(+), suggested an open-channel block mechanism. The properties of block were predicted from a computational model where 17-β-estradiol binds to open K(+) channels. It was concluded that 17-β-estradiol rapidly reduces voltage-gated K(+) currents in a way consistent with an open-channel block mechanism. This suggests a new mechanism for steroid action on ion channels.

  • 243.
    East, Emma
    et al.
    Department of Life Health & Chemical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
    Johns, Noémie
    Department of Life Health & Chemical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
    Georgiou, Melanie
    Department of Life Health & Chemical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
    Golding, Jon P.
    Department of Life Health & Chemical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
    Loughlin, A. Jane
    Department of Life Health & Chemical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Phillips, James B.
    Department of Life Health & Chemical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK, Department of Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, 256 Gray’s Inn Road, London WC1X 8LD, UK.
    A 3D in vitro model reveals differences in the astrocyte response elicited by potential stem cell therapies for CNS injury2013In: Regenerative Medicine, ISSN 1746-0751, E-ISSN 1746-076X, Vol. 8, no 6, p. 739-746Article in journal (Refereed)
    Abstract [en]

    AIM: This study aimed to develop a 3D culture model to test the extent to which transplanted stem cells modulate astrocyte reactivity, where exacerbated glial cell activation could be detrimental to CNS repair success.

    MATERIALS & METHODS: The reactivity of rat astrocytes to bone marrow mesenchymal stem cells, neural crest stem cells (NCSCs) and differentiated adipose-derived stem cells was assessed after 5 days. Schwann cells were used as a positive control.

    RESULTS: NCSCs and differentiated Schwann cell-like adipose-derived stem cells did not increase astrocyte reactivity. Highly reactive responses to bone marrow mesenchymal stem cells and Schwann cells were equivalent.

    CONCLUSION: This approach can screen therapeutic cells prior to in vivo testing, allowing cells likely to trigger a substantial astrocyte response to be identified at an early stage. NCSCs and differentiated Schwann cell-like adipose-derived stem cells may be useful in treating CNS damage without increasing astrogliosis.

  • 244.
    Edin, Benoni
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Assigning biological functions: Making sense of causal chains2008In: Synthese, ISSN 0039-7857, E-ISSN 1573-0964, Vol. 161, no 2, p. 203-218Article in journal (Refereed)
  • 245.
    Edin, Benoni
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Quantitative analyses of dynamic strain sensitivity in human skin mechanoreceptors.2004In: Journal of Neurophysiology, ISSN 0022-3077, Vol. 92, no 6, p. 3233-43Article in journal (Refereed)
    Abstract [en]

    Microneurographical recordings from 24 slowly adapting (SA) and 16 fast adapting (FA) cutaneous mechanoreceptor afferents were obtained in the human radial nerve. Most of the afferents innervated the hairy skin on the back of the hand. The afferents' receptive fields were subjected to controlled strains in a ramp-and-hold fashion with strain velocities from 1 to 64%.s(-1), i.e., strain velocities within most of the physiological range. For all unit types, the mean variation in response onset approached 1 ms for strain velocities >8%.s(-1). Except at the highest strain velocities, the first spike in a typical SAIII unit was evoked at strains <0.5% and a typical SAII unit began to discharge at <1% skin strain. Skin strain velocity had a profound effect on the discharge rates of all classes of afferents. The "typical" peak discharge rate at the highest strain velocity studied was 50-95 imp/s(-1) depending on unit type. Excellent fits were obtained for both SA and FA units when their responses to ramp stretches were modeled by simple power functions (r2 > 0.9 for 95% of the units). SAIII units grouped with SAII with respect to onset latency and onset variation but with SAI units with respect to dynamic strain sensitivity. Because both SA and FA skin afferents respond strongly, quickly, and accurately to skin strain changes, they all seem to be able to provide useful information about movement-related skin strain changes and therefore contribute to proprioception and kinesthesia.

  • 246.
    Edin, Benoni B.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Classification of muscle stretch receptor afferents in humans1988Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The response patterns of human stretch receptors in the finger extensor muscles of the forearm were studied using the microneurography technique. Single-unit recordings were obtained from one-hundred and twenty-four afferents. A procedure was developed to classify the units in muscle spindle primary afferents, secondary afferents, and Golgi tendong organ afferents. The procedure allows an objective and reproducible classification on the basis of the afferents’ responses to a series of tests which individually are non-conclusive.

    It was demonstrated that maximal twitch contractions can be elicited in the finger extensor muscles of the forearm, without causing undue discomfort to the subjects, or hazarding the single-unit recording. The response of the units to this test allowed, in most cases but not always, a separation in muscle spindle and tendon organ afferents. Thus the test was not adequate for an unequivocal classification.

    Three discrete response parameters were extracted from ramp-and-hold stretches, viz. the presence or absence of an initial burst and a deceleration response, and prompt silencing at slow muscle shortening. The distributions of the parameters were significantly different among the three unit types. These parameters which were pair-wise independent constituted a set of considerable discriminative power. It was shown that human muscle spindles have about the same static position sensitivity to fractional muscle stretch as previously found in animals.

    Stretch sensitization was demonstrated by rapid, repeated stretches of the muscle which enhanced the réponse to subsequent slow stretches of muscle spindles. Sensitization was different with primary and secondary muscle spindle afferents whereas Golgi tendon organ afferents never displayed stretch sensitization.

    One-to-one driving with small-amplitude sinusoidal stretches superimposed on ramp-and- hold stretches was almost exclusively seen with primary muscle spindle afferents, whereas secondaries seldom and tendon organ afferents never displayed driving.

    The afferent responses during slowly increasing isometric contractions and rapid relaxations were analysed. An increased discharge rate on relaxation was common among spindle afferents whereas it was never seen in tendon organs afferents. Two separate groups of spindles afferents were found with regard to fusimotor recruitment. The largest group was recruited at rather low and variable contractile forces whereas the smaller group was not recruited at all.

    The proportions of the three unit types, spindle primary, spindle secondary, and Golgi tendon organ afferents were estimated from a preliminary classification and the distribution of the eight response features were analyzed for each class of afferents. On the basis of these estimates and the response pattern of the individual unit Bayes’ theorem was used to calculate the probabilities that the unit was a spindle primary, a spindle secondary, or a tendon organ afferent. Estimates indicate that about 19 out of 20 muscle afferents are correctly classified when all eight features are analyzed.

  • 247.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Cutaneous afferents provide information about knee joint movements in humans.2001In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 531, no Pt 1, p. 289-297Article in journal (Refereed)
    Abstract [en]

    1. Neurophysiological evidence that afferent information from skin receptors is important for proprioception has been gathered mainly in experiments relating to the human hand and finger joints. To investigate if proprioceptive information is also provided by skin mechanoreceptor afferents from skin areas related to large joints of postural importance, microneurography recordings were obtained in humans from skin afferents in the lateral cutaneous femoral nerve to study their responses to knee joint movements. 2. Data were collected from 60 sequentially recorded afferents from slowly (n = 23) and fast (n = 6) adapting low-threshold mechanoreceptors, hair follicle receptors (n = 24), field receptors (n = 1) and C mechanoreceptors (n = 6). Fascicular recordings showed that the lateral cutaneous femoral nerve supplies extensive areas of the thigh: from 5-10 cm below the inguinal ligament down to below and lateral to the knee joint; accordingly, the afferents originated in receptors located in wide areas of the human thigh. 3. All afferents from fast and slowly adapting low-threshold mechanoreceptors, as well as C mechanoreceptors, responded to manually applied skin stretch. In contrast, the same stimulus elicited, at most, feeble responses in hair follicle receptors. 4. Qualitative and quantitative analyses of the responses of a subset of afferents revealed that in particular slowly adapting afferents effectively encode both static and dynamic aspects of passively imposed knee joint movements. 5. It was concluded that receptors in the hairy skin of humans can provide high-fidelity information about knee joint movements. A previously undefined type of slowly adapting receptor (SA III) seemed particularly suited for this task whereas this does not seem to be the case for either hair follicle receptors or C mechanoreceptors.

  • 248.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Finger joint movement sensitivity of non-cutaneous mechanoreceptor afferents in the human radial nerve.1990In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 82, no 2, p. 417-422Article in journal (Refereed)
    Abstract [en]

    The responses of non-cutaneous receptors in the human hand to normal digit movements were studied using single afferent recordings from the radial nerve. Eight joint-related afferents had thresholds of 50 mN or less. All responded to passive flexion movements within the physiological range of joint rotation and showed predominantly static response sensitivity; none increased its discharge during passive extension. However, only two of these eight afferents showed the same response pattern during active movements; three discharged only during the extension phase whereas the other three discharged both during extension and flexion. No high-threshold, joint-related mechanoreceptive afferents were encountered in a population of 148 afferents recorded from the cutaneous portion of the radial nerve indicating a scarcity of such afferents on the dorsal aspect of finger joints. Seven high-threshold, subcutaneous mechanoreceptive units not related to joints had thresholds for indentations of 50 mN or more and lacked responses to finger movements. Low-threshold mechanoreceptive afferents related to joints in the human hand may thus provide kinematic information in the physiological mid-range of both passive and active movements. Joint position cannot, however, be derived unambiguously from their discharge since the receptor responses may be dramatically altered by muscle activity.

  • 249.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Quantitative analysis of static strain sensitivity in human mechanoreceptors from hairy skin.1992In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 67, no 5, p. 1105-1113Article in journal (Refereed)
    Abstract [en]

    1. Microelectrode recordings from 15 slowly adapting (SA) cutaneous mechanoreceptor afferents originating in hairy skin were obtained from the radial nerve in humans. 2. Controlled skin stretch was applied to the back of the hand that encompassed the physiological range of skin stretch during movements at the metacarpophalangeal (MCP) joints. 3. Both SA Group I and II afferents showed exquisite dynamic and static sensitivity to skin stretch. The median static strain sensitivity was 1.0 imp.s-1 per percent skin stretch for SAI units and 1.8 for SAII units. 4. Translated into sensitivity to movements at the MCP joint, both SAI and SAII afferents in the skin of the back of the hand displayed a positional sensitivity that was comparable with that reported for muscle spindle afferents. 5. These data give quantitative support to suggestions that skin receptors in the human hairy skin provide information on nearby joint configurations and therefore may play a specific role in proprioception, kinesthesia, and motor control.

  • 250.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    The 'initial burst' of human primary muscle spindle afferents has at least two components.1991In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 143, no 2, p. 169-175Article in journal (Refereed)
    Abstract [en]

    Ten muscle spindle primary afferents from the extensor digitorum communis muscle of man were studied with single unit afferent recordings. Responses to slow test stretches with three different pre-history conditions were assessed to investigate the contribution of rapid stretches to the stretch sensitization phenomenon. In two of the conditions, the slow test ramps were preceded by rapid stretch after which the parent muscle of the receptor was either (a) kept short for 5 seconds or (b) kept long for 3.2 seconds and then returned to the short muscle length for 5 seconds. The third condition (c) consisted of a slow stretch from short to long muscle length followed by a rapid return to the short muscle length, in turn followed by 5 seconds at the short muscle length. Afferent responses were depressed when the muscle had been kept at the long length after the rapid stretches (condition b) and enhanced when the muscle had been kept at the short length (conditions a & c). A prominent 'initial burst' was only present in the afferent discharge when the parent muscles of the primary endings had been kept short (condition a). A second, more prolonged burst was present for conditions (a) and (c) but was lacking or inconspicuous when the muscle had been kept long after rapid stretches (condition b). The rapid stretches in the stretch sensitization paradigm appear to be a primary factor not only for the enhanced responses of sensitized primary afferents but also for the depressed responses of desensitized primary afferents.

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