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  • 1.
    Ahmadi, Mahboobah
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Andersen, Peter M
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Human extraocular muscles in ALS2010In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 51, no 7, p. 3494-3501Article in journal (Refereed)
    Abstract [en]

    PURPOSE. To investigate the general morphology, fiber type content, and myosin heavy chain (MyHC) composition of extraocular muscles (EOMs) from postmortem donors with amyotrophic lateral sclerosis (ALS) and to evaluate whether EOMs are affected or truly spared in this disease. METHODS. EOM and limb muscle samples obtained at autopsy from ALS donors and EOM samples from four control donors were processed for immunohistochemistry with monoclonal antibodies against distinct MyHC isoforms and analyzed by SDS-PAGE. In addition, hematoxylin and eosin staining and nicotinamide tetrazolium reductase (NADH-TR) activity were studied. RESULTS. Wide heterogeneity was observed in the appearance of the different EOMs from each single donor and between donors, irrespective of ALS type or onset. Pathologic morphologic findings in ALS EOMs included presence of atrophic and hypertrophic fibers, either clustered in groups or scattered; increased amounts of connective tissue; and areas of fatty replacement. The population of fibers stained with anti-MyHCslow tonic was smaller than that of MyHCIpositive fibers and was mostly located in the orbital layer in most of the ALS EOM samples, whereas an identical staining pattern for both fiber populations was observed in the control specimens. MyHCembryonic was notably absent from the ALS EOMs. CONCLUSIONS. The EOMs showed signs of involvement with altered fiber type composition, contractile protein content, and cellular architecture. However, when compared to the limb muscles, the EOMs were remarkably preserved. EOMs are a useful model for the study of the pathophysiology of ALS.

  • 2.
    Byström, Berit
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Carracedo, Sergio
    Behndig, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Gullberg, Donald
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Alpha11 integrin in the human cornea: importance in development and disease.2009In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 50, no 11, p. 5044-5053Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To examine the distribution of the alpha11 integrin chain in the human cornea during fetal development and in normal and diseased adult human corneas.

    METHODS: Six fetal corneas, 10 to 20 weeks of gestation (wg), and 18 adult corneas including 3 normal, 7 with keratoconus, 5 with pseudophakic bullous keratopathy (PBK), 2 with Fuchs' corneal dystrophy, and 1 with a scar after deep lamellar keratoplasty (DLKP) were processed for immunohistochemistry with specific antibodies against the alpha11 integrin chain; collagen I, IV, and V; and alpha-smooth muscle actin (alpha-SMA). The cellular source of alpha11 integrin chain was further investigated in cell cultures.

    RESULTS: At 10 to 17 wg, the alpha11 integrin chain was predominantly present in the anterior corneal stroma. At 20 wg, in normal adult corneas and in Fuchs' dystrophy corneas there was weak staining in the stroma. The PBK corneas showed variable and weak staining, generally accentuated in the posterior stroma near Descemet's membrane. In contrast, the anterior portion of the stroma in the keratoconus corneas was strongly stained in an irregular streaky pattern. Human corneal fibroblasts/myofibroblasts produced alpha11 integrin chain in culture. Cultures treated with TGF-beta showed higher content of both alpha-SMA and the alpha11 integrin chain.

    CONCLUSIONS: The presence of the alpha11 integrin chain during early corneal development and the enhanced expression in scarred keratoconus corneas indicates that this integrin chain is likely to play an important role in collagen deposition during corneal development and in keratoconus with a scarring component and compromised basement membrane integrity.

  • 3.
    Byström, Berit
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Vicente, André
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Notch1 Signaling Pathway in Aniridia- Related Keratopathy, Normal Fetal and Adult Human Corneas2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 9Article in journal (Other academic)
    Abstract [en]

    Purpose : Notch1 is suggested to play an important role during tissue development and in differentiation of the corneal epithelial cells whereas its inhibitors Dlk1 and Numb keep these cells in an immature status. Our purpose was to evaluate the presence of these factors in aniridia-related keratopathy (ARK) and in normal fetal and adult human corneas.

    Methods : Two human fetal corneas, 10 and 20 weeks of gestation, two naïve corneal buttons from patients with advanced ARK, three corneal buttons from patients with ARK undergoing re-transplantation, as well as two adult healthy control corneas were processed for immunohistochemistry using antibodies against Notch1, Dlk1 and Numb.

    Results : Identical staining patterns were found for Notch1 in normal adult and fetal corneas, with staining around the basal epithelial cells and in a few streaks in the stroma. In ARK corneas, Notch1 was not detected in the pannus of the stroma. On the contrary, the pannus in ARK was labeled with antibodies against Dlk1. Dlk1 was also abundant in the epithelium and in the stroma of fetal corneas but was absent from the stroma of normal adult corneas. Numb was present in the adult normal corneas and in addition labeled the ARK and fetal corneas in a pattern resembling that of Dlk1.

    Conclusions : The lack of Notch1 together with abundant Dlk1 and Numb, suggest a disturbed balance between these important factors in ARK, likely to hamper differentiation of the progenitor cell population and to be important for the pathophysiology of ARK.

  • 4.
    Byström, Berit
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Virtanen, Ismo
    Rousselle, Patricia
    Gullberg, Donald
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Distribution of laminins in the developing human eye2006In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 47, no 3, p. 777-785Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To examine the distribution of laminin (Ln) chains in basement membranes (BMs) of the human cornea, lens, and retina in fetal development. METHODS: Ten fetal eyes (9-20 weeks of gestation [wg]) were serially sectioned and treated with specific antibodies against the Ln-alpha1, -alpha2, -alpha3, -alpha4, -alpha5, -beta1, -beta2, -beta3, and -gamma1 chains. RESULTS: The BM of the corneal epithelium was reactive for Ln-alpha3, -alpha5, -beta1, and beta3 chains through all ages, whereas the Ln-alpha1 chain was present at 9 to 12 wg and the Ln-alpha4 chain from 10 wg. The Descemet's membrane (DM) was labeled with the Ln-alpha1 and -alpha4 chains at 10 to 17 wg, the Ln-alpha5 chain from 10 wg, the Ln-beta1 chain at 11 to 17 wg, and the Ln-beta3 chain from 17 wg. The Ln-alpha1, alpha5, -beta1, and -beta2 chains were present in the lens capsule and the internal limiting membrane (ILM) through all ages. The Bruch's membrane (BrM) was immunoreactive for the Ln-alpha3, alpha4, -alpha5, -beta1, and -beta2 chains through all ages, whereas the Ln-alpha1 chain was absent from 20 wg onward. The Ln-alpha2 chain was not detected in the eye, but it was present in the extraocular muscles. CONCLUSIONS: BMs play an important role during morphogenesis, in that they influence cell proliferation, migration, and tissue differentiation. Lns are the major noncollagenous component of BMs. The presence of four different alpha chains, three beta chains, and one gamma chain of Ln in the eye reveals a high degree of complexity from the early stages of development and suggests an important role for the different Ln chains in human ocular differentiation.

  • 5.
    Byström, Berit
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Virtanen, Ismo
    Rousselle, Patricia
    Miyazaki, Kaoru
    Lindén, Christina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Laminins in normal, keratoconus, bullous keratopathy and scarred human corneas2007In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 127, no 6, p. 657-667Article in journal (Refereed)
    Abstract [en]

    The laminin composition (LMalpha1-alpha5, beta1-beta3, gamma1 and gamma2 chains) of normal corneas and corneal buttons from keratoconus, bullous keratopathy (BKP), Fuchs' dystrophy + BKP, Fuchs' dystrophy without BKP and scar after deep lamellar keratoplasty (DLKP) was investigated with immunohistochemistry. The epithelial basement membranes (BMs) of both normal and diseased corneas contained LMalpha3, alpha5, beta1, beta3, gamma1 and gamma2 chains. The epithelial BM morphology was altered in the different diseases. Scarring was associated with irregular BM and ectopic stromal localization of different laminin chains. The Descemet's membrane (DM) contained LMalpha5, beta1 and gamma1 chains in all cases and additionally LMbeta3 and gamma2 chains in the majority of keratoconus corneas. The interface in the DLKP cornea had patches of LMalpha3, alpha4, alpha5, beta1 and beta2 chains, and an extra BM-like structure under the Bowman's membrane. These results suggest that laminin chains participate in the process of corneal scarring and in the pathogenesis of some corneal diseases. The novel finding of LMalpha3, beta3 and gamma2 in the DM of keratoconus buttons indicates that this membrane is also involved in the disease and that some cases of keratoconus may have a congenital origin, without normal downregulation of the LMbeta3 chain.

  • 6.
    Chandra, Naresh
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Section of Virology.
    Liu, Yan
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Frängsmyr, Lars
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Section of Virology.
    Wu, Nian
    Silva, Lisete M
    Lindström, Mona
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Chai, Wengang
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Feizi, Ten
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Section of Virology.
    Sulfated Glycosaminoglycans as Viral Decoy Receptors for Human Adenovirus Type 372019In: Viruses, E-ISSN 1999-4915, Vol. 11, no 3, article id E247Article in journal (Refereed)
    Abstract [en]

    Glycans on plasma membranes and in secretions play important roles in infection by many viruses. Species D human adenovirus type 37 (HAdV-D37) is a major cause of epidemic keratoconjunctivitis (EKC) and infects target cells by interacting with sialic acid (SA)-containing glycans via the fiber knob domain of the viral fiber protein. HAdV-D37 also interacts with sulfated glycosaminoglycans (GAGs), but the outcome of this interaction remains unknown. Here, we investigated the molecular requirements of HAdV-D37 fiber knob:GAG interactions using a GAG microarray and demonstrated that fiber knob interacts with a broad range of sulfated GAGs. These interactions were corroborated in cell-based assays and by surface plasmon resonance analysis. Removal of heparan sulfate (HS) and sulfate groups from human corneal epithelial (HCE) cells by heparinase III and sodium chlorate treatments, respectively, reduced HAdV-D37 binding to cells. Remarkably, removal of HS by heparinase III enhanced the virus infection. Our results suggest that interaction of HAdV-D37 with sulfated GAGs in secretions and on plasma membranes prevents/delays the virus binding to SA-containing receptors and inhibits subsequent infection. We also found abundant HS in the basement membrane of the human corneal epithelium, which may act as a barrier to sub-epithelial infection. Collectively, our findings provide novel insights into the role of GAGs as viral decoy receptors and highlight the therapeutic potential of GAGs and/or GAG-mimetics in HAdV-D37 infection.

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  • 7. Crippa, Sylvain, V
    et al.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Kawasaki, Aki
    Chromatic pupillometry in children2018In: Frontiers in Neurology, E-ISSN 1664-2295, Vol. 9, article id 669Article in journal (Refereed)
    Abstract [en]

    Chromatic pupillometry is a technique that is increasingly used to assess retinal disorders. As age may be one of the various factors which can influence the pupillary light reaction, this study aimed to evaluate the pupil responses to colored light stimuli in the pediatric population. Fifty-three children with normal vision and without any history of ocular disorders were tested with a portable pupillometer. Four test sequences were used: five dim blue (470 nm) stimuli presented in half log steps ranging from -3.15 to -1.15 log cd/m(2) after 3 min of dark adaptation, five red (622 nm) stimuli of -1.15, -0.7, -0.15, 0.3, and 0.85 log cd/m(2) after 1 min light adaptation, one bright blue stimulus of 2.2 log cd/m(2) and one bright red of 2 log cd/m(2). The results were grouped by age: a younger group included 27 children aged from 3 to 10 years old and an older group included 26 from 10 and 1 month to 18 years old. The younger group had a smaller pupil diameter after dark adaptation compared with the older group. A linear regression defining the photopic threshold showed that younger subjects had a higher threshold, e.g., needed a brighter red stimulus to evoke a threshold pupil response comparable that of subjects. Age thus seems to influence outer retinal sensitivity at least as evaluated by the pupillary photopic threshold intensity. The post-illumination pupillary reaction was used as a marker of intrinsic melanopsin activity and did not show any difference between the two age groups.

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  • 8.
    Dennhag, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences.
    Kahsay, Abraha
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nissen, Itzel
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM).
    Chermenina, Maria
    Umeå University, Faculty of Medicine, Department of Clinical Sciences.
    Nord, Hanna
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Liu, Jiao
    Arner, Anders
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Backman, Ludvig J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Remeseiro, Silvia
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM).
    von Hofsten, Jonas
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences. Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    fhl2b expression ameliorates muscular dystrophyManuscript (preprint) (Other academic)
  • 9.
    Dennhag, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    Kahsay, Abraha
    Umeå University, Faculty of Medicine, Department of Medical and Translational Biology. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Nissen, Itzel
    Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM). Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    Nord, Hanna
    Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    Chermenina, Maria
    Umeå University, Faculty of Medicine, Department of Medical and Translational Biology. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Liu, Jiao
    Div. Thoracic Surgery, Dept. Clinical Sciences, Lund University, Lund, Sweden; College of Life Sciences, South-Central University for Nationalities, Wuhan, China.
    Arner, Anders
    Div. Thoracic Surgery, Dept. Clinical Sciences, Lund University, Lund, Sweden.
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    Backman, Ludvig J.
    Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    Remeseiro, Silvia
    Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM). Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    von Hofsten, Jonas
    Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Medical and Translational Biology.
    fhl2b mediates extraocular muscle protection in zebrafish models of muscular dystrophies and its ectopic expression ameliorates affected body muscles2024In: Nature Communications, E-ISSN 2041-1723, Vol. 15, no 1, article id 1950Article in journal (Refereed)
    Abstract [en]

    In muscular dystrophies, muscle fibers loose integrity and die, causing significant suffering and premature death. Strikingly, the extraocular muscles (EOMs) are spared, functioning well despite the disease progression. Although EOMs have been shown to differ from body musculature, the mechanisms underlying this inherent resistance to muscle dystrophies remain unknown. Here, we demonstrate important differences in gene expression as a response to muscle dystrophies between the EOMs and trunk muscles in zebrafish via transcriptomic profiling. We show that the LIM-protein Fhl2 is increased in response to the knockout of desmin, plectin and obscurin, cytoskeletal proteins whose knockout causes different muscle dystrophies, and contributes to disease protection of the EOMs. Moreover, we show that ectopic expression of fhl2b can partially rescue the muscle phenotype in the zebrafish Duchenne muscular dystrophy model sapje, significantly improving their survival. Therefore, Fhl2 is a protective agent and a candidate target gene for therapy of muscular dystrophies.

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  • 10.
    Dennhag, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nord, Hanna
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    von Hofsten, Jonas
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Absence of Desmin in Myofibers of the Zebrafish Extraocular Muscles2020In: Translational Vision Science & Technology, E-ISSN 2164-2591, Vol. 9, no 10, article id 1Article in journal (Refereed)
    Abstract [en]

    Purpose: To study the medial rectus (MR) muscle of zebrafish (Danio rerio) with respect to the pattern of distribution of desmin and its correlation to distinct types of myofibers and motor endplates.

    Methods: The MRs of zebrafish were examined using confocal microscopy in whole-mount longitudinal specimens and in cross sections processed for immunohistochemistry with antibodies against desmin, myosin heavy chain isoforms, and innervation markers. Desmin patterns were correlated to major myofiber type and type of innervation. A total of 1382 myofibers in nine MR muscles were analyzed.

    Results: Four distinct desmin immunolabeling patterns were found in the zebrafish MRs. Approximately a third of all slow myofibers lacked desmin, representing 8.5% of the total myofiber population. The adult zebrafish MR muscle displayed en grappe, en plaque, and multiterminal en plaque neuromuscular junctions (NMJs) with intricate patterns of desmin immunolabeling.

    Conclusions: The MRs of zebrafish showed important similarities with the human extraocular muscles with regard to the pattern of desmin distribution and presence of the major types of NMJs and can be regarded as an adequate model to further study the role of desmin and the implications of heterogeneity in cytoskeletal protein composition.

    Translational Relevance: The establishment of a zebrafish model to study the cytoskeleton in muscles that are particularly resistant to muscle disease opens new avenues to understand human myopathies and muscle dystrophies and may provide clues to new therapies.

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  • 11.
    Domellöf, Fatima Pedrosa
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Liu, Jing-Xiu
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    The cytoskeleton of myotendinous junctions in human extraocular muscles2020In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 61, no 7Article in journal (Other academic)
    Abstract [en]

    Purpose: To systematically investigate the composition of the cytoskeleton of the myotendinous junctions (MTJs) in human extraocular muscles (EOMs).

    Methods: Ten human EOM samples collected with ethical permission were processed for immunofluorescence with antibodies against the cytoskeletal proteins desmin, nestin, vimentin and cytokeratin 19; various myosin heavy chain (MyHC) isoforms as well as antibodies against tenascin or laminin to identify the MTJs.

    Results: The majority of the MTJs in both orbital and global layer contained desmin but an important proportion of them did not show increased levels of immunostaining at the folds of the MTJ, in contrast to other muscles. Desmin was absent from approximately 15% of the MTJs and mostly in myofibers containing MyHCIIa. Nestin was present in approximately 91% of the MTJs. Four different combinations were encountered regarding immunolabeling for desmin+nestin at the MTJs, including absence of both in a subgroup of MTJs, irrespective of fiber type. Vimentin was not present at the MTJs and cytokeratin 19 was either present or absent from the MTJs.

    Conclusions: The present data on the composition of the cytoskeleton at the MTJs in the EOMs raises fundamental questions regarding our previous knowledge on the role of these proteins for force transmission. We propose a novel model to further investigate these questions.

  • 12.
    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)
  • 13.
    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.

  • 14. Fischer, M Dominik
    et al.
    Budak, Murat T
    Bakay, Marina
    Gorospe, J Rafael
    Kjellgren, Daniel
    Pedrosa-Domellöf, F
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Hoffman, Eric P
    Khurana, Tejvir S
    Definition of the unique human extraocular muscle allotype by expression profiling.2005In: Physiol Genomics, ISSN 1531-2267, Vol. 22, no 3, p. 283-91Article in journal (Refereed)
    Abstract [en]

    The extraocular muscles (EOMs) are a unique group of specialized muscles that are anatomically and physiologically distinct from other skeletal muscles. Perhaps the most striking characteristic of the EOMs is their differential sensitivity to disease. EOMs are spared in Duchenne's muscular dystrophy (DMD) despite widespread involvement of other skeletal muscles. Conversely, they are early and prominent targets in myasthenia gravis and mitochondrial myopathies. It is unclear how EOMs achieve such specialization or a differential response to diseases; however, this has been attributed to a unique, group-specific pattern of gene expression or "allotype." To begin to address these issues as well as define the human EOM allotype, we analyzed the human EOM transcriptome using oligonucleotide-based expression profiling. Three hundred thirty-eight genes were found to be differentially expressed in EOM compared with quadriceps femoris limb muscle, using a twofold cutoff. Functional characterization revealed expression patterns corresponding to known metabolic and structural properties of EOMs such as expression of EOM-specific myosin heavy chain (MYH13) and high neural, vascular, and mitochondrial content, suggesting that the profiling was sensitive and specific. Genes related to myogenesis, stem cells, and apoptosis were detected at high levels in normal human EOMs, suggesting that efficient and continuous regeneration and/or myogenesis may be a mechanism by which the EOMs remain clinically and pathologically spared in diseases such as DMD. Taken together, this study provides insight into how human EOMs achieve their unique structural, metabolic, and pathophysiological properties.

  • 15.
    Fischer, M Dominik
    et al.
    University of Pennsylvania School of Medicine.
    Gorospe, J Rafael
    George Washington University, Washington.
    Felder, Edward
    University of Pennsylvania School of Medicine, Philadelphia.
    Bogdanovich, Sasha
    University of Pennsylvania School of Medicine.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Ahima, Rexford S
    University of Pennsylvania School of Medicine, Philadelphia.
    Rubinstein, Neal A
    University of Pennsylvania School of Medicine, Philadelphia.
    Hoffman, Eric P
    George Washington University, Washington.
    Khurana, Tejvir S
    University of Pennsylvania School of Medicine.
    Expression profiling reveals metabolic and structural components of extraocular muscles2002In: Physiological Genomics, ISSN 1094-8341, E-ISSN 1531-2267, Vol. 9, no 2, p. 71-84Article in journal (Refereed)
    Abstract [en]

    The extraocular muscles (EOM) are anatomically and physiologically distinct from other skeletal muscles. EOM are preferentially affected in mitochondrial myopathies, but spared in Duchenne's muscular dystrophy. The anatomical and pathophysiological properties of EOM have been attributed to their unique molecular makeup: an allotype. We used expression profiling to define molecular features of the EOM allotype. We found 346 differentially expressed genes in rat EOM compared with tibialis anterior, based on a twofold difference cutoff. Genes required for efficient, fatigue-resistant, oxidative metabolism were increased in EOM, whereas genes for glycogen metabolism were decreased. EOM also showed increased expression of genes related to structural components of EOM such as vessels, nerves, mitochondria, and neuromuscular junctions. Additionally, genes related to specialized functional roles of EOM such as the embryonic and EOM-specific myosin heavy chains and genes for muscle growth, development, and/or regeneration were increased. The EOM expression profile was validated using biochemical, structural, and molecular methods. Characterization of the EOM expression profile begins to define gene transcription patterns associated with the unique anatomical, metabolic, and pathophysiological properties of EOM.

  • 16.
    Granberg, I
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Lindell, Björn
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Eriksson, Per-Olof
    Umeå University, Faculty of Medicine, Department of Odontology, Clinical Oral Physiology.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Capillary supply in relation to myosin heavy chain fibre composition of human intrinsic tongue muscles2010In: Cells Tissues Organs, ISSN 1422-6405, E-ISSN 1422-6421, Vol. 192, no 5, p. 303-313Article in journal (Refereed)
    Abstract [en]

    The capillary supply and myosin heavy chain (MyHC) composition of three different intrinsic tongue muscles was analysed in the anterior and posterior regions of the human tongue with biochemical and immunohistochemical techniques. Mean capillary density for the whole tongue was 796 ± 82 cap/mm², without regional differences. The overall number of capillaries around each fibre (CAF) was higher in the posterior than in the anterior region (2.5 vs. 2.1, p = 0.009). However, correcting for regional differences in fibre size, CAF per fibre area was higher in the anterior region (4.3 vs. 3.0, p < 0.001). Muscle fibres containing fast MyHCs predominated in the anterior region (78.7%), consisting of MyHCIIa (58.5%), MyHCIIx (1.0%), MyHCIIa+MyHCIIx (11.3%) and MyHCI+MyHCIIa (7.9%). Fibres containing slow MyHC predominated in the posterior region (65.2%), consisting of MyHCI (45.5%) and MyHCI+MyHCIIa (19.7%). A minor fibre population (<2%) contained unusual MyHC isoforms, namely MyHC foetal, MyHC slow-tonic, MyHC α-cardiac or MyHC embryonic. The microvascularization of the human tongue was twice as high as in human limb muscles. Regional similarities in capillary supply, but differences in fibre phenotype composition, suggest that human tongue muscle fibres are fatigue resistant independently of MyHC content. High frequency of hybrid fibres, that is fibres co-expressing two or more MyHC isoforms, indicates a wider spectrum of fibre contractile properties than in limb muscles. In conclusion, human intrinsic tongue muscles showed internal specialization in distribution of MyHC isoforms and capillary supply, but not in the expression of unusual MyHCs.

  • 17.
    Hadrevi, Jenny
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Hellström, Fredrik
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Kieselbach, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Malm, Christer
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Protein differences between human trapezius and vastus lateralis muscles determined with a proteomic approach2011In: BMC Musculoskeletal Disorders, E-ISSN 1471-2474, Vol. 12, no 181, p. 11-Article in journal (Refereed)
    Abstract [en]

    Background: The trapezius muscle is a neck muscle that is susceptible to chronic pain conditions associated with repetitive tasks, commonly referred to as chronic work-related myalgia, hence making the trapezius a muscle of clinical interest. To provide a basis for further investigations of the proteomic traits of the trapezius muscle in disease, two-dimensional difference gel electrophoresis (2D-DIGE) was performed on the healthy trapezius using vastus lateralis as a reference. To obtain as much information as possible from the vast proteomic data set, both one-way ANOVA, with and without false discovery rate (FDR) correlation, and partial least square projection to latent structures with discriminant analysis (PLS-DA) were combined to compare the outcome of the analysis.

    Results: The trapezius and vastus lateralis showed significant differences in metabolic, contractile and regulatory proteins, with different results depending on choice of statistical approach and pre-processing technique. Using the standard method, FDR correlated one-way ANOVA, 42 protein spots differed significantly in abundance between the two muscles. Complementary analysis using immunohistochemistry and western blot confirmed the results from the 2D-DIGE analysis.

    Conclusions: The proteomic approach used in the present study combining 2D-DIGE and multivariate modelling provided a more comprehensive comparison of the protein profiles of the human trapezius and vastus lateralis muscle, than previously possible to obtain with immunohistochemistry or SDS-PAGE alone. Although 2D-DIGE has inherent limitations it is particularly useful to comprehensively screen for important structural and metabolic proteins, and appears to be a promising tool for future studies of patients suffering from chronic work related myalgia or other muscle diseases.

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  • 18.
    Harandi, Vahid M
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Gaied, Aida RN
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Unchanged neurotrophic factors and their receptors correlate with sparing in extraocular muscles in amyotrophic lateral sclerosis2016In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 57, no 15, p. 6831-6842Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate the impact of amyotrophic lateral sclerosis (ALS) on the extraocular muscles (EOMs) by examining the distribution of neurotrophic factors (NTFs) and their receptors in EOMs and limb muscles from ALS transgenic mice.

    Methods: Muscle samples collected from transgenic mice overexpressing human superoxide dismutase type 1 mutations (SOD1G93A, the most widely used mouse model of ALS) at 50 and 150 days as well as age-matched controls were analyzed with immunohistochemistry using antibodies against brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin-4/5 (NT-4), glial cell line-derived neurotrophic factor (GDNF), and the neurotrophin receptors p75NTR, tyrosine kinase (Trk) receptor TrkB and TrkC, and GDNF family receptor alpha-1 (GFRα-1).

    Results: There was an intrinsic difference in NTF expression between EOMs and limb muscles in control mice: EOMs presented significantly lower number of neuromuscular junctions (NMJs) labeled for BDNF and NT-4 at 50 days, and for BDNF and GDNF at 150 days, compared with the control limb muscles of corresponding age. In ALS transgenic mice at 150 days, NTF expression in limb muscles was significantly changed but not in EOMs: the limb muscles presented a significant decline in the number of NMJs labeled for BDNF, NT-4, GDNF, p75NTR, TrkB, and TrkC, which was not observed in EOMs.

    Conclusions: The significant differences in expression of NTFs on NMJs between EOMs and limb muscles in both control and ALS transgenic mice suggest that NTF may be involved in the pathogenesis of ALS and the resistance of EOMs to the disease.

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  • 19.
    Janbaz, Adrihan H.
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Lindström, Mona
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Liu, Jingxia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Intermediate Filaments in the Human Extraocular Muscles2014In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 55, no 8, p. 5151-5159Article in journal (Refereed)
    Abstract [en]

    PURPOSE.

    To investigate the distribution of the intermediate filament (IF) proteins desmin, vimentin, and nestin in human extraocular muscles (EOMs). METHODS. Healthy adult EOM samples were serially sectioned (5 and 1 mu m) and processed for immunohistochemistry, with specific antibodies (Abs) against desmin, vimentin, and nestin and different myosin heavy chains (MyHCs), including the newly characterized Ab MYH7b against MyHC slow tonic. The distribution of desmin was also studied in EOMs at 16 to 18 weeks of gestation.

    RESULTS.

    Desmin was present in the vast majority of muscle fibers. Notably, muscle fibers that contained MyHC slow tonic were either unlabeled or very weakly labeled with three different Abs against desmin. These muscle fibers had normal cytoarchitecture and intact basement membrane. In fetal muscle, desmin was also absent or weak in myotubes containing MyHC slow tonic. Nestin was detected in a large proportion of muscle fibers in the orbital layer and to some extent also in the global layer, whereas no muscle fibers contained vimentin. Desmin and nestin were enriched at neuromuscular junctions, as in limb muscle. In contrast, some myotendinous junctions lacked desmin or nestin.

    CONCLUSIONS.

    The human EOMs differed significantly from the other muscles in the body with respect to their IF composition. Desmin, hitherto regarded as a ubiquitous muscle cytoskeletal protein, was absent or only present in trace amounts in a subset of normal muscle fibers in adult and fetal EOMs. Nestin, normally downregulated early in the postnatal period, was present in a high proportion of adult muscle fibers.

  • 20.
    Kahsay, Abraha
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Dennhag, Nils
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Liu, Jing-Xia
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nord, Hanna
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Rönnbäck, Hugo
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Thorell, Anna Elisabeth
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    von Hofsten, Jonas
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Obscurin maintains myofiber identity in extraocular muscles2024In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 65, no 2, article id 19Article in journal (Refereed)
    Abstract [en]

    Purpose: The cytoskeleton of the extraocular muscles (EOMs) is significantly different from that of other muscles. We aimed to investigate the role of obscurin, a fundamental cytoskeletal protein, in the EOMs.

    Methods: The distribution of obscurin in human and zebrafish EOMs was compared using immunohistochemistry. The two obscurin genes in zebrafish, obscna and obscnb, were knocked out using CRISPR/Cas9, and the EOMs were investigated using immunohistochemistry, qPCR, and in situ hybridization. The optokinetic reflex (OKR) in five-day-old larvae and adult obscna−/−;obscnb−/− and sibling control zebrafish was analyzed. Swimming distance was recorded at the same age.

    Results: The obscurin distribution pattern was similar in human and zebrafish EOMs. The proportion of slow and fast myofibers was reduced in obscna−/−;obscnb−/− zebrafish EOMs but not in trunk muscle, whereas the number of myofibers containing cardiac myosin myh7 was significantly increased in EOMs of obscurin double mutants. Loss of obscurin resulted in less OKRs in zebrafish larvae but not in adult zebrafish.

    Conclusions: Obscurin expression is conserved in normal human and zebrafish EOMs. Loss of obscurin induces a myofiber type shift in the EOMs, with upregulation of cardiac myosin heavy chain, myh7, showing an adaptation strategy in EOMs. Our model will facilitate further studies in conditions related to obscurin.

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  • 21.
    Kjellgren, Daniel
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Ryan, Michelle
    Ohlendieck, Kay
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Sarco(endo)plasmic reticulum ca2+ATPases (SERCA1 and 2) in human extraocular muscles2003In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 44, no 12, p. 5057-5062Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To investigate the composition of the fibers in human extraocular muscles (EOMs) with respect to the sarco(endo)plasmic reticulum Ca(2+)ATPases (SERCA)-1 and -2 and to investigate possible correlations between SERCA and myosin heavy chain (MyHC) composition. METHODS: EOM samples were processed for immunocytochemistry with monoclonal antibodies specific against SERCA1 (fast isoform), SERCA2 (slow isoform), or different MyHCs. A total of 1571 fibers were analyzed. Microsomal EOM fractions were analyzed with SDS-PAGE and immunoblots. RESULTS: The fast fibers, containing MyHCIIa, accounted for 79% of the fibers in the orbital layer (OL) and 74% in the global layer (GL). More than 99% of these fibers contained SERCA1, and 86% of them coexpressed SERCA1 and -2. Almost all slow fibers stained with SERCA2; 54% of those in the GL and all in the OL coexpressed SERCA1 and -2. Fifteen percent of the fibers in the GL and less than 1% in the OL were MyHCeom(pos)/MyHCIIa(neg) fibers. All these contained SERCA1 and in the OL also stained strongly with anti-SERCA2. Biochemically SERCA2 was more abundant than SERCA1. CONCLUSIONS: The human EOMs had a very complex pattern of expression of the major protein regulating fiber relaxation rate. The coexistence of SERCA1 and -2, together with complex mixtures of MyHCs in most of the fibers provide the human EOMs with a unique molecular portfolio that allows a highly specific fine-tuning regimen of contraction and relaxation.

  • 22.
    Kjellgren, Daniel
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Larsson, Lars
    Uppsala University.
    Fürst, Dieter
    University of Bonn.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Uncoordinated expression of myosin heavy chains and myosin-binding protein C isoforms in human extraocular muscles2006In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 47, no 10, p. 4188-4193Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To examine the distribution of myosin-binding protein C (MyBP-C) in human extraocular muscles (EOMs) and to correlate the myosin heavy chain (MyHC) and the MyBP-C composition of the fibers. METHODS: Samples from 17 EOMs, 3 levator palpebrae (LP), and 6 limb muscles were analyzed with SDS-PAGE and immunoblot or processed for immunocytochemistry with monoclonal antibodies (mAbs) against MyBP-C-fast, MyBP-C-slow, MyHCIIa, MyHCI, MyHCsto, MyHCalpha-cardiac, and MyHCemb. RESULTS: In the limb muscle samples, fast fibers were labeled with anti-MyBP-C-fast and anti-MyBP-C-slow, whereas the slow fibers were immunostained with anti-MyBP-C-slow only, in accordance with previous studies. In 11 EOM samples MyBP-C-fast was not detected, and weak staining with anti-MyBP-C-fast was seen only in a few fibers in the proximal part of 2 muscles. The mAb against MyBP-C-slow labeled all fibers, but fibers containing MyHCI were generally more strongly stained. In the levator palpebrae, immunostaining with anti-MyBP-C-fast was present in some fibers labeled with anti-MyHCIIa and/or anti-MyHCeom. MyBP-C-fast and -intermediate were not detected biochemically in the EOMs. CONCLUSIONS: The lack of MyBP-C-fast and intermediate is an additional feature of the human EOM allotype. The true EOMs have a unique myofibrillar protein isoform composition reflecting their special structural and functional properties. The levator palpebrae muscle phenotype is intermediate between that of the EOMs and the limb muscles.

  • 23.
    Kjellgren, Daniel
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Andersen, Jesper
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Myosin heavy chain isoforms in human extraocular muscle2003In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 44, no 4, p. 1419-1425Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To investigate the myosin heavy chain (MyHC) composition of human extraocular (EOM) and levator palpebrae (LP) muscle fibers. METHODS: Adult human EOMs and LP were studied with SDS-PAGE, immunoblots, and immunocytochemistry, with antibodies against six MyHC isoforms. Myofibrillar adenosine triphosphatase (mATPase) and reduced nicotinamide adenine dinucleotide (NADH)-TR activity and fiber area were also determined. RESULTS: Most of the fibers in both layers stained strongly with anti-MyHCIIa. Approximately 14% of the fibers in the global layer and 16% in the orbital layer were labeled with anti-MyHCI. The remaining 24% of the fibers in the global layer and 3% in the orbital layer were not stained with either of these two antibodies, but were reactive to anti-MyHCeom (MyHCeom(pos)/MyHCIIa(neg) fibers). The fibers stained with anti-MyHCI had acid-stable mATPase activity, and the remainder of the fibers had alkaline-stable mATPase activity. Almost all the slow fibers stained with both anti-MyHCI and anti-MyHCslow tonic in both layers. Anti-MyHCalpha-cardiac stained approximately 26% of these slow fibers in the orbital layer and 7% in the global layer. Some slow fibers in both layers lacked staining with anti-MyHCslow tonic or with anti-MyHCalpha-cardiac. MyHCemb and/or MyHCeom were also present in some of the fibers of all the groups. The LP did not stain with anti-MyHCslow tonic. CONCLUSIONS: The present study revealed that the human EOMs have a very complex fiber type and MyHC composition and differ significantly from the EOMs of other species. The features of the LP were distinct from those of the four recti, the obliquus superior, and the limb muscles.

  • 24.
    Kjellgren, Daniel
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Virtanen, Ismo
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Laminin isoforms in human extraocular muscles2004In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 45, no 12, p. 4233-4239Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To determine the laminin isoform composition of the basement membranes (BMs) in the human extraocular muscles (EOMs) and relate it to the fact that EOMs are spared in laminin alpha2-chain-deficient congenital muscular dystrophy. METHODS: Samples from adult human EOMs and limb muscle were processed for immunocytochemistry, with monoclonal antibodies against laminin chains (Ln) alpha1 to -5, beta1 and -2, and gamma1. Neuromuscular junctions (NMJs) were identified with acetylcholinesterase reaction. The capillary density was measured in sections stained with anti-Lnalpha5. RESULTS: The extrasynaptic BM of the EOM muscle fibers contained Lnalpha2, -beta1, -beta2, and -gamma1, and, in contrast to limb muscle, it also contained Lnalpha4 and -alpha5, to some extent. The distinct laminin composition of the EOMs was confirmed by the presence of Lutheran protein, an alpha5-chain-specific receptor not found in limb muscle. At the NMJs, there was increased expression of Lnalpha4 and expression of Lnalpha2, -alpha5, -beta1, -beta2, and -gamma1 was also maintained. The capillary density was very high (1050 +/- 190 capillaries/mm(2)) in the EOMs and significantly (P < 0.05) higher in the orbital (1170 +/- 180 capillaries/mm(2)) than in the global (930 +/- 110 capillaries/mm(2)) layer. CONCLUSIONS: The human EOMs showed important differences in laminin isoform composition and capillary density when compared with human limb muscle and muscles of other species. The presence of additional laminin isoforms other than laminin-2 in the BM of the extrasynaptic sarcolemma could partly explain the sparing of the EOMs in Lnalpha2-deficient congenital muscular dystrophy.

  • 25.
    Lindström, Mona
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Satellite cell heterogeneity with respect to expression of MyoD, myogenin, Dlk1 and c-Met in human skeletal muscle: application to a cohort of power lifters and sedentary men2010In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 134, no 4, p. 371-385Article in journal (Refereed)
    Abstract [en]

    Human satellite cells (SCs) are heterogeneous with respect to markers for their identification in the niche between the muscle fibre plasma membrane and its basal lamina. We have previously shown that, in biopsies from highly competitive power lifters, power lifters with long-term use of anabolic steroids and a population of healthy sedentary men, antibodies against the neuronal cell adhesion molecule (NCAM) and the paired box transcription factor Pax7 together label 94% of the SCs, NCAM alone labels 4% and Pax7 alone labels 1%. In the present study, we have further studied these biopsies with four markers related to SC activation and differentiation. Our study unequivocally shows that staining for MyoD and myogenin are present in nuclei of SCs and of myoblasts and myotubes in areas of muscle fibre regeneration. Staining for c-Met was observed in a proportion of Pax7+ SCs. However, widespread labelling of the sarcolemma precluded the quantification of c-Met+/Pax7+ SCs and the use of c-Met as a reliable SC marker. Pax7+ SCs labelled by anti-Delta like1 (Dlk1) were present in all samples but in variable proportions, whereas muscle progenitor cells related to repair were Dlk1⁻. Staining for Dlk1 was also observed in Pax7⁻ interstitial cells and in the cytoplasm of some small muscle fibres. Interestingly, the proportion of Dlk1+/Pax7+ SCs was significantly different between the groups of power lifters. Thus, our study confirms that human SCs show marked heterogeneity and this is discussed in terms of SC activation, myonuclei turnover, muscle fibre growth and muscle fibre damage and repair.

  • 26.
    Lindström, Mona
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Tjust, Anton E.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Pax7-Positive Cells/Satellite Cells in Human Extraocular Muscles2015In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 56, no 10, p. 6132-6143Article in journal (Refereed)
    Abstract [en]

    PURPOSE. We quantified and investigated the distribution of Pax7-positive cells/satellite cells (SCs) in the human extraocular muscles (EOMs). METHODS. An immunofluorescence multiple-marker method simultaneously combining two SC markers (Pax7, NCAM), detection of the basement membrane (laminin) and cell nuclei (4',6-diamidino-2-phenylindole [DAPI]), was used on the anterior, middle, and posterior portions of EOMs from five healthy donors. Pax7-positive cell and SC content, myonuclear content, myofiber cross-sectional area, and myonuclear domain were analyzed in single cross-sections. Between 3915 and 13,536 myofibers per muscle cross-section and myofibers from the entire EOM cross-section were analyzed for quantification of Pax7-positive cells per myofiber (Pax7/F).

    RESULTS. The number of Pax7/F in the human EOMs varies along the length of the muscle with twice as high Pax7/F in the anterior part of the EOMs, but within the range of what has been previously reported for normal adult limb muscles. Furthermore, there are Pax7-positive cells in positions other than the classical SC position and the myonuclear domain size of adult EOMs is noticeably smaller than that previously reported for other adult skeletal muscles.

    CONCLUSIONS. Previous data on differences in Pax7-positive cell/SC abundance between EOMs and limb muscles must be reconsidered and the characteristics of different Pax7-positive cell populations further investigated. Higher numbers of Pax7-positive cells in the anterior portion of the EOMs may have a bearing for strabismus surgery involving sectioning of the muscle fibers.

  • 27.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Andersen, Peter M
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Different impact of ALS on laminin isoforms in human extraocular muscles versus limb muscles2011In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 52, no 7, p. 4842-4852Article in journal (Refereed)
    Abstract [en]

    Purpose. To determ ine the impact of amyotrophic lateral sclerosis (ALS) on the extraocular muscles (EOMs) by examining the laminin isoform composition of the basement membranes (BMs) in EOMs and limb muscles from donors with ALS.

    Methods. Muscle samples collected at autopsy from ALS donors and from transgenic mice overexpressing human SOD1 mutations (D90A or G93A), and age-matched controls were analyzed with immunohistochemistry using antibodies against laminin chain α2 (Lnα2), Lnα4, Lnα5, Lnβ1, Lnβ2 and Lnγ1. Neuromuscular junctions (NMJs) were identified with α-bungarotoxin.

    Results. Lnα2, the hallmark chain of skeletal muscle, and Lnβ2 were absent or partially absent from the BMs in a variable number of muscle fibers in most of the ALS EOMs. Three ALS donors showed dramatic decrease in the levels of these chains around their muscle fibers and NMJs. Changes in Lnα2 were not age-related and were also present in EOMs of ALS mouse models. Lnα4 was preserved in the majority of NMJs in EOM but absent in the majority of NMJs in limb muscle of ALS. The BMs around muscle fibers, NMJs, nerves and blood vessels of the majority of EOMs of ALS donors had rather normal appearance and laminin composition, but heterogeneity was observed among EOM samples of individual ALS donors and between ALS donors.

    Conclusions. The present study showed distinct impact of ALS on EOMs as compared to limb muscles. The EOMs maintained a normal laminin composition in their NMJs which may be instrumental for the fact that they are not typically affected in ALS.

  • 28.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Andersen, Peter M
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Distinct changes in synaptic protein composition at neuromuscular junctions of extraocular muscles versus limb muscles of ALS donors2013In: PLOS ONE, E-ISSN 1932-6203, Vol. 8, no 2, p. e57473-Article in journal (Refereed)
    Abstract [en]

    The pathophysiology of amyotrophic lateral sclerosis (ALS) is very complex and still rather elusive but in recent years evidence of early involvement of the neuromuscular junctions (NMJs) has accumulated. We have recently reported that the human extraocular muscles (EOMs) are far less affected than limb muscles at the end-stage of ALS from the same donor. The present study aimed to compare the differences in synaptic protein composition at NMJ and in nerve fibers between EOM and limb muscles from ALS donors and controls. Neurofilament light subunit and synaptophysin decreased significantly at NMJs and in nerve fibers in limb muscles with ALS whereas they were maintained in ALS EOMs. S100B was significantly decreased at NMJs and in nerve fibers in both EOMs and limb muscles of ALS donors, but other markers confirmed the presence of terminal Schwann cells in these NMJs. p75 neurotrophin receptor was present in nerve fibers but absent at NMJs in ALS limb muscles. The EOMs were able to maintain the integrity of their NMJs to a very large extent until the end-stage of ALS, in contrast to the limb muscles. Changes in Ca2+ homeostasis, reflected by altered S100B distribution, might be involved in the breakdown of nerve-muscle contact at NMJs in ALS.

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  • 29.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Dennhag, Nils
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Understanding the extraocular muscles: Connective tissue, motor endplates and the cytoskeleton2020In: The Biochemist, ISSN 0954-982X, Vol. 42, no 5, p. 52-57Article in journal (Refereed)
    Abstract [en]

    We constantly direct our eyes to the object of interest with the help of the extraocular muscles, andthereby use foveal fixation to attain the best possible visual acuity. The muscles around the eye arerather different from other skeletal muscles, being, for example, simultaneously the fastest musclesin the body and impossible to exhaust. The most exciting property of the extraocular muscles is theirunique response to disease, as they often remain unaffected in muscle conditions which lead tosevere handicap and premature death. Understanding the coping strategies that allow the extraocularmuscles to remain unaffected may provide clues for the future treatment of severe diseases such asmuscle dystrophies.

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  • 30.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Complex Correlations Between Desmin Content, Myofiber Types, and Innervation Patterns in the Human Extraocular Muscles2020In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 61, no 3, article id 15Article in journal (Refereed)
    Abstract [en]

    PURPOSE. To investigate whether the distribution of intermediate filament protein desmin is related to the different patterns of innervation in the human extraocular muscles (EOMs).

    METHODS. EOM samples were analyzed with immunohistochemistry using antibodies against desmin, vimentin, different myosin heavy chain (MyHC) isoforms, and fetal and adult acetylcholine receptor (AChR) subunits. Neuromuscular junctions (NMJs) were identified with alpha-bungarotoxin or with antibodies against neurofilament and synaptophysin.

    RESULTS. Desmin was present in the vast majority of myofibers, but it was weakly present or absent in a limited area in the close vicinity of the single en plaque NMJs in less than half of these myofibers. Desmin was either present or lacking in MyHCsto/I myofibers displaying multiple en grappe endings but present in MyHCsto/I myofibers receiving spiral nerve endings. In MyHCeom myofibers displaying multiterminal en plaque endings, desmin was either present or absent irrespective of AChR subunits or EOM layer. Vimentin did not substitute for the lack of desmin.

    CONCLUSIONS. The results indicate that the human EOMs have a more complex cytoskeletal organization than other muscles and suggest additional signalling mechanisms from the NMJs to the myofibers.

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  • 31.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Domellöf, Fatima Pedrosa
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Cytoskeletal Proteins in Myotendinous Junctions of Human Extraocular Muscles2021In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 62, no 2, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Purpose: The purpose of this study was to investigate the cytoskeletal composition of myotendinous junctions (MTJs) in the human extraocular muscles (EOMs). Desmin and other major cytoskeletal proteins are enriched at the MTJs of ordinary myofibers, where they are proposed to be of particular importance for force transmission and required to maintain myofiber integrity. Methods: EOM and limb muscle samples were analyzed with immunohistochemistry using antibodies against the intermediate filament proteins desmin, nestin, keratin 19, vimentin, and different myosin heavy chain (MyHC) isoforms. MTJs were identified by labeling with antibodies against laminin or tenascin. Results: In contrast to MTJs in lumbrical muscle where desmin, nestin, and keratin 19 were always present, approximately one-third of the MTJs in the EOMs lacked either desmin and/or nestin, and all MTJs lacked keratin 19. Approximately 6% of the MTJs in the EOMs lacked all of these key cytoskeletal proteins. Conclusions: The cytoskeletal protein composition of MTJs in human EOMs differed significantly from that of MTJs in limb muscles. These differences in cytoskeletal protein composition may indicate particular adaptation to meet the functional requirements of the EOMs.

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  • 32.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Eriksson, Per-Olof
    Umeå University, Faculty of Medicine, Department of Odontology, Clinical Oral Physiology.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Fiber content and myosin heavy chain composition of muscle spindles in aged human biceps brachii2005In: Journal of Histochemistry and Cytochemistry, ISSN 0022-1554, E-ISSN 1551-5044, Vol. 53, no 4, p. 445-454Article in journal (Refereed)
    Abstract [en]

    The present study investigated potential age-related changes in human muscle spindles with respect to the intrafusal fiber-type content and myosin heavy chain (MyHC) composition in biceps brachii muscle. The total number of intrafusal fibers per spindle decreased significantly with aging, due to a significant reduction in the number of nuclear chain fibers. Nuclear chain fibers in old spindles were short and some showed novel expression of MyHC alpha-cardiac. The expression of MyHC alpha-cardiac in bag1 and bag2 fibers was greatly decreased in the A region. The expression of slow MyHC was increased in nuclear bag1 fibers and that of fetal MyHC decreased in bag2 fibers whereas the patterns of distribution of the remaining MyHC isoforms were generally not affected by aging. We conclude that aging appears to have an important impact on muscle spindle composition. These changes in muscle spindle phenotype may reflect an age-related deterioration in sensory and motor innervation and are likely to have an impact in motor control in the elderly.

  • 33.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Eriksson, Per-Olof
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Myosin heavy chain composition of muscle spindles in human biceps brachii2002In: Histochem Cell Biol, Vol. 50, no 2, p. 171-184Article in journal (Refereed)
    Abstract [en]

    Data on the myosin heavy chain (MyHC) composition of human muscle spindles are scarce in spite of the well-known correlation between MyHC composition and functional properties of skeletal muscle fibers. The MyHC composition of intrafusal fibers from 36 spindles of human biceps brachii muscle was studied in detail by immunocytochemistry with a large battery of antibodies. The MyHC content of isolated muscle spindles was assessed with SDS-PAGE and immunoblots. Four major MyHC isoforms (MyHCI, IIa, embryonic, and intrafusal) were detected with SDS-PAGE. Immunocytochemistry revealed very complex staining patterns for each intrafusal fiber type. The bag(1) fibers contained slow tonic MyHC along their entire fiber length and MyHCI, alpha-cardiac, embryonic, and fetal isoforms along a variable part of their length. The bag(2) fibers contained MyHC slow tonic, I, alpha-cardiac, embryonic, and fetal isoforms with regional variations. Chain fibers contained MyHCIIa, embryonic, and fetal isoforms throughout the fiber, and MyHCIIx at least in the juxtaequatorial region. Virtually each muscle spindle had a different allotment of numbers of bag(1), bag(2) and chain fibers. Taken together, the complexity in intrafusal fiber content and MyHC composition observed indicate that each muscle spindle in the human biceps has a unique identity.

  • 34.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    A novel type of multiterminal motor endplate in human extraocular muscles2018In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 59, no 1, p. 539-548Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate the relation between type of motor endplate, acetylcholine receptor (AChR) subunit composition, and fiber types in human extraocular muscles (EOMs).

    Methods: EOM samples collected from subjects aged 34 to 82 years were serially sectioned and processed for immunohistochemistry, with specific antibodies against different myosin heavy chain (MyHC) isoforms, neurofilament, synaptophysin, and adult epsilon (ε) and fetal gamma (γ) AChR subunits as well as α-bungarotoxin.

    Results: A novel type of motor endplate consisting of large, multiterminal en plaque endings was found in human EOMs, in addition to the previously well-described single en plaque and multiple en grappe endplates. Such novel endplates were abundant but exclusively observed in myofibers lacking MyHC slow and fast IIa but containing MyHC extraocular (MyHCeom), isoforms. Multiple en grappe endings were found only in myofibers containing MyHC slow-tonic isoform and contained fetal γ AChR subunit. Adult ε and fetal γ AChR subunits, alone or combined, were found in the multiterminal endplates. Distinct AChR subunits were present in adjacent motor endplates of a given myofiber containing MyHCeom.

    Conclusions: Human EOMs have a more complex innervation pattern than previously described, comprising also a novel type of multiterminal motor endplate present in myofibers containing MyHCeom. The heterogeneity in AChR subunit composition in a given myofiber suggests the possible presence of polyneuronal innervation in human EOMs.

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  • 35.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Distribution of SERCA isoforms in human intrafusal fibers2003In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 120, no 4, p. 299-306Article in journal (Refereed)
    Abstract [en]

    The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) is a membrane protein that plays a crucial role in muscle relaxation by transporting cytosolic Ca2+ into the lumen of the sarco/endoplasmic reticulum. In this study, the presence of SERCA1 and SERCA2 was investigated in human intrafusal fibers by immunocytochemistry. Nuclear bag1 fibers contained both SERCA1 and SERCA2 isoforms, with predominant staining seen with SERCA2 in the A and B regions. Most nuclear bag2 fibers also contained SERCA1 and SERCA2 isoforms and their coexistence frequently occurred in the A region. SERCA1 was present whereas SERCA2 was generally absent in the nuclear chain fibers. The staining intensity seen with the SERCA1 monoclonal antibody varied in the order of chain>bag1>bag2. The expression of SERCA1 isoform was found to correlate with the presence of fast myosin heavy chain (MyHC) isoform in nuclear chain fibers, whereas for nuclear bag fibers there was no such apparent correlation between patterns of expression of SERCA and MyHC isoforms. The phenotype revealed for the human bag fibers was very sophisticated and adapted to attain a very wide range of contraction and relaxation velocities.

  • 36.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Thornell, Lars-Eric
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa-Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Muscle spindles in the deep muscles of the human neck: a morphological and immunocytochemical study2003In: Journal of Histochemistry and Cytochemistry, ISSN 0022-1554, E-ISSN 1551-5044, Vol. 51, no 2, p. 175-186Article in journal (Refereed)
    Abstract [en]

    Muscle spindle density is extremely high in the deep muscles of the human neck. However, there is a paucity of information regarding the morphology and immunoreactivity of these muscle spindles. The objective of this study was to investigate the intrafusal fiber content and to assess the myosin heavy chain (MyHC) composition of muscle spindles from human deep neck muscles. In addition to the conventional spindles containing bag(1), bag(2), and chain fibers (b(1)b(2)c spindle), we observed a number of spindles lacking bag(1) (b(2)c spindle) or bag(2) (b(1)c spindle) fibers. Both bag(1) and bag(2) fibers contained slow tonic MyHCs along their entire fiber length and MyHCI, MyHCIIa, embryonic, and alpha-cardiac MyHC isoforms along a variable length of the fibers. Fetal MyHC was present in bag(2) fibers but not in bag(1) fibers. Nuclear chain fibers contained MyHCIIa, embryonic, and fetal isoforms with regional variations. We also compared the present data with our previous results obtained from muscle spindles in human biceps brachii and the first lumbrical muscles. The allotment of numbers of intrafusal fibers and the MyHC composition showed some muscle-related differences, suggesting functional specialization in the control of movement among different human muscles.

  • 37.
    Liu, Jing-Xia
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.