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Di Trani N, Racca N, Demarchi D, Grattoni A. Comprehensive Analysis of Electrostatic Gating in Nanofluidic Systems. ACS Appl Mater Interfaces 2022; 14:35400-35408. [PMID: 35905377 DOI: 10.1021/acsami.2c08809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Molecular transport in nanofluidic systems exhibits properties that are unique to the nanoscale. Here, the electrostatic and steric interactions between particle and surfaces become dominant in determining particle transport. At the solid-liquid interface of charged surfaces an electric double layer (EDL) forms due to electrostatic interactions between surfaces and charged particles. In these systems, tunable charge-selective nanochannels can be generated by manipulating electrostatic gating via co-ions exclusion and counterions enrichment of the EDL at the solid-liquid interface. In this context, electrostatic gating has been used to modulate the selectivity of nanofluidic membranes for drug delivery, nanofluidic transistors, and FlowFET, among other applications. While an extensive body of literature investigating nanofluidic systems exists, there is a lack of a comprehensive analysis accounting for all major parameters involved in these systems. Here we performed an all-encompassing modeling investigation corroborated by experimental analysis to assess the influence of nanochannel size, electrolyte properties, surface chemistry, gate voltage, dielectric properties, and molecular charge and size on the exclusion and enrichment of charged analytes in nanochannels. We found that the leakage current in electrostatic gating, often overlooked, plays a dominant role in molecular exclusion. Importantly, by independently considering all ionic species, we found that counterions compete for EDL formation at the surface proximity, resulting in concentration distributions that are nearly impossible to predict with analytical models. Achieving a deeper understanding of these nanofluidic phenomena will help the development of innovative miniaturized systems for both medical and industrial applications.
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Affiliation(s)
- Nicola Di Trani
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, Texas 77030, United States
| | - Nevio Racca
- Department of Electronics and Telecommunications, Polytechnic of Turin, 10129 Turin, Italy
| | - Danilo Demarchi
- Department of Electronics and Telecommunications, Polytechnic of Turin, 10129 Turin, Italy
| | - Alessandro Grattoni
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, Texas 77030, United States
- Department of Surgery, Houston Methodist Research Institute, Houston, Texas 77030, United States
- Department of Radiation Oncology, Houston Methodist Research Institute, Houston, Texas 77030, United States
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Spitschan M, Mead J, Roos C, Lowis C, Griffiths B, Mucur P, Herf M, Nam S, Veitch JA. luox: validated reference open-access and open-source web platform for calculating and sharing physiologically relevant quantities for light and lighting. Wellcome Open Res 2022; 6:69. [PMID: 34017925 PMCID: PMC8095192 DOI: 10.12688/wellcomeopenres.16595.3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2022] [Indexed: 11/22/2023] Open
Abstract
Light exposure has a profound impact on human physiology and behaviour. For example, light exposure at the wrong time can disrupt our circadian rhythms and acutely suppress the production of melatonin. In turn, appropriately timed light exposure can support circadian photoentrainment. Beginning with the discovery that melatonin production is acutely suppressed by bright light more than 40 years ago, understanding which aspects of light drive the 'non-visual' responses to light remains a highly active research area, with an important translational dimension and implications for "human-centric" or physiologically inspired architectural lighting design. In 2018, the International Commission on Illumination (CIE) standardised the spectral sensitivities for predicting the non-visual effects of a given spectrum of light with respect to the activation of the five photoreceptor classes in the human retina: the L, M and S cones, the rods, and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Here, we described a novel, lean, user-friendly, open-access and open-source platform for calculating quantities related to light. The platform, called luox, enables researchers and research users in vision science, lighting research, chronobiology, sleep research and adjacent fields to turn spectral measurements into reportable quantities. The luox code base, released under the GPL-3.0 License, is modular and therefore extendable to other spectrum-derived quantities. luox calculations of CIE quantities and indices have been endorsed by the CIE following black-box validation.
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Affiliation(s)
- Manuel Spitschan
- Department of Experimental Psychology, University of Oxford, Oxford, UK
- Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, UK
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
- TUM Department of Sport and Health Sciences (TUM SG), Chronobiology & Health, Technical University of Munich, Munich, Germany
- Max Planck Institute for Biological Cybernetics, Translational Sensory & Circadian Neuroscience, Tübingen, Germany
- TUM Institute for Advanced Study (TUM-IAS), Technical University of Munich, Garching, Germany
| | | | | | | | | | | | | | - Somang Nam
- National Research Council of Canada, Construction Research Centre, Ottawa, Canada
| | - Jennifer A. Veitch
- National Research Council of Canada, Construction Research Centre, Ottawa, Canada
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Lee SS, Koishi A, Bourg IC, Fenter P. Ion correlations drive charge overscreening and heterogeneous nucleation at solid-aqueous electrolyte interfaces. Proc Natl Acad Sci U S A 2021; 118:e2105154118. [PMID: 34353907 DOI: 10.1073/pnas.2105154118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Ion distributions at charged solid–water interfaces, referred to as the electrical double layer (EDL), are poorly understood at high ion concentrations, in part due to the lack of molecular-scale descriptions of the interactions between adsorbed hydrated ions. Here, direct visualization of the salinity-dependent evolution of EDL structure reveals molecular origins of nonclassical transformation of the EDL, in which charge overscreening and heterogeneous nucleation are driven by ion–ion correlations at the interfaces. This manifestation of the atomistic basis of nonclassical behaviors provides a much-needed understanding of the impact of ion cooperativity at charged interfaces for the development of predictive models for element transport in natural environments and advanced technologies for material growth and synthesis in saline environments. Classical electrical double layer (EDL) models are foundational to the representation of atomistic structure and reactivity at charged interfaces. An important limitation to these models is their dependence on a mean-field approximation that is strictly valid for dilute aqueous solutions. Theoretical efforts to overcome this limitation are severely impeded by the lack of visualization of the structure over a wide range of ion concentration. Here, we report the salinity-dependent evolution of EDL structure at negatively charged mica–water interfaces, revealing transition from the Langmuir-type charge compensation in dilute salt solutions to nonclassical charge overscreening in highly concentrated solutions. The EDL structure in this overcharging regime is characterized by the development of both lateral positional correlation between adsorbed ions and vertical layering of alternating cations and anions reminiscent of the structures of strongly correlated ionic liquids. These EDL ions can spontaneously grow into nanocrystalline nuclei of ionic compounds at threshold ion concentrations that are significantly lower than the bulk solubility limit. These results shed light on the impact of ion cooperativity that drives heterogeneous nonclassical behaviors of the EDL in high-salinity conditions.
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Spitschan M, Mead J, Roos C, Lowis C, Griffiths B, Mucur P, Herf M. luox: novel validated open-access and open-source web platform for calculating and sharing physiologically relevant quantities for light and lighting. Wellcome Open Res 2021; 6:69. [PMID: 34017925 PMCID: PMC8095192 DOI: 10.12688/wellcomeopenres.16595.2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2021] [Indexed: 12/16/2022] Open
Abstract
Light exposure has a profound impact on human physiology and behaviour. For example, light exposure at the wrong time can disrupt our circadian rhythms and acutely suppress the production of melatonin. In turn, appropriately timed light exposure can support circadian photoentrainment. Beginning with the discovery that melatonin production is acutely suppressed by bright light more than 40 years ago, understanding which aspects of light drive the 'non-visual' responses to light remains a highly active research area, with an important translational dimension and implications for "human-centric" or physiologically inspired architectural lighting design. In 2018, the International Commission on Illumination (CIE) standardised the spectral sensitivities for predicting the non-visual effects of a given spectrum of light with respect to the activation of the five photoreceptor classes in the human retina: the L, M and S cones, the rods, and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Here, we described a novel, lean, user-friendly, open-access and open-source platform for calculating quantities related to light. The platform, called luox, enables researchers and research users in chronobiology, sleep research and adjacent field to turn spectral measurements into reportable quantities. The luox code base, released under the GPL-3.0 License, is modular and therefore extendable to other spectrum-derived quantities. luox has been endorsed by the CIE following black-box validation.
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Affiliation(s)
- Manuel Spitschan
- Department of Experimental Psychology, University of Oxford, Oxford, UK.,Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, Oxford, UK.,Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland.,Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
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Park JW, Thomas SM, Schechter AN, Piknova B. Control of rat muscle nitrate levels after perturbation of steady state dietary nitrate intake. Nitric Oxide 2021; 109-110:42-49. [PMID: 33713800 PMCID: PMC8020733 DOI: 10.1016/j.niox.2021.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/02/2021] [Accepted: 03/05/2021] [Indexed: 12/17/2022]
Abstract
The roles of nitrate and nitrite ions as nitric oxide (NO) sources in mammals, complementing NOS enzymes, have recently been the focus of much research. We previously reported that rat skeletal muscle serves as a nitrate reservoir, with the amount of stored nitrate being highly dependent on dietary nitrate availability, as well as its synthesis by NOS1 enzymes and its subsequent utilization. We showed that at conditions of increased NO need, this nitrate reservoir is used in situ to generate nitrite and NO, at least in part via the nitrate reductase activity of xanthine oxidoreductase (XOR). We now further investigate the dynamics of nitrate/nitrite fluxes in rat skeletal muscle after first increasing nitrate levels in drinking water and then returning to the original intake level. Nitrate/nitrite levels were analyzed in liver, blood and several skeletal muscle samples, and expression of proteins involved in nitrate metabolism and transport were also measured. Increased nitrate supply elevated nitrate and nitrite levels in all measured tissues. Surprisingly, after high nitrate diet termination, levels of both ions in liver and all muscle samples first declined to lower levels than the original baseline. During the course of the overall experiment there was a gradual increase of XOR expression in muscle tissue, which likely led to enhanced nitrate to nitrite reduction. We also noted differences in basal levels of nitrate in the different types of muscles. These findings suggest complex control of muscle nitrate levels, perhaps with multiple processes to preserve its intracellular levels.
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Affiliation(s)
- Ji Won Park
- Molecular Medicine Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Samantha M Thomas
- Molecular Medicine Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Alan N Schechter
- Molecular Medicine Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Barbora Piknova
- Molecular Medicine Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
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Guarner J, Schroeder LF, Amukele TK. Three Approaches to Creating an Essential Diagnostics List. Am J Clin Pathol 2019; 151:443-445. [PMID: 30551217 DOI: 10.1093/ajcp/aqy167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jeannette Guarner
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA
| | - Lee F Schroeder
- Department of Pathology, University of Michigan School of Medicine, Ann Arbor
| | - Timothy K Amukele
- Department of Pathology and Laboratory Medicine, Johns Hopkins University, Baltimore, MD
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Liang AP, Drazick AT, Gao H, Li Y. Skeletal muscle secretion of IL-6 is muscle type specific: Ex vivo evidence. Biochem Biophys Res Commun 2018; 505:146-50. [PMID: 30241947 DOI: 10.1016/j.bbrc.2018.09.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 09/07/2018] [Indexed: 01/18/2023]
Abstract
Emerging evidence indicates that skeletal muscle possesses endocrine function to secret myokines. Interleukin 6 (IL-6) is a well-characterized myokine that is involved in regulation of metabolism and muscle function. Metabolism type and contractile dynamics vary in different muscle types. It is not clear, however, if IL-6 secretion differs in different muscle types. In this study, we first established an ex vivo approach to test the inducible muscle secretion. Freshly isolated muscles were incubated in Krebs solution at 37 °C with oxygen supply. Secreted IL-6 in the incubation media was measure using Western blot and ELISA assay. We first confirmed that the IL-6 release was inducible by treating the incubated muscle with a cytokine stimulant. We demonstrated that physiological temperature (37 °C) and O2 supply were essential for the induction of IL-6 release from the incubated muscle, suggesting it is a controlled secretion rather than a spontaneous leak. Using this approach, we found that IL-6 release was only inducible from soleus muscle but not EDL muscle. We further showed that IL-6 protein level was higher in slow oxidative muscle fibers. Moreover, we showed that EDL, although lacks of IL-6 release, surely has inducible secretory function that had different secretory pattern from soleus.
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Gerlinger-Romero F, Guimarães-Ferreira L, Yonamine CY, Salgueiro RB, Nunes MT. Effects of beta-hydroxy-beta-methylbutyrate (HMB) on the expression of ubiquitin ligases, protein synthesis pathways and contractile function in extensor digitorum longus ( EDL) of fed and fasting rats. J Physiol Sci 2018; 68:165-174. [PMID: 28083734 PMCID: PMC10717962 DOI: 10.1007/s12576-016-0520-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/30/2016] [Indexed: 12/01/2022]
Abstract
Beta-hydroxy-beta-methylbutyrate (HMB), a leucine metabolite, enhances the gain of skeletal muscle mass by increasing protein synthesis or attenuating protein degradation or both. The aims of this study were to investigate the effect of HMB on molecular factors controlling skeletal muscle protein synthesis and degradation, as well as muscle contractile function, in fed and fasted conditions. Wistar rats were supplied daily with HMB (320 mg/kg body weight diluted in NaCl-0.9%) or vehicle only (control) by gavage for 28 days. After this period, some of the animals were subjected to a 24-h fasting, while others remained in the fed condition. The EDL muscle was then removed, weighed and used to evaluate the genes and proteins involved in protein synthesis (AKT/4E-BP1/S6) and degradation (Fbxo32 and Trim63). A sub-set of rats were used to measure in vivo muscle contractile function. HMB supplementation increased AKT phosphorylation during fasting (three-fold). In the fed condition, no differences were detected in atrogenes expression between control and HMB supplemented group; however, HMB supplementation did attenuate the fasting-induced increase in their expression levels. Fasting animals receiving HMB showed improved sustained tetanic contraction times (one-fold) and an increased muscle to tibia length ratio (1.3-fold), without any cross-sectional area changes. These results suggest that HMB supplementation under fasting conditions increases AKT phosphorylation and attenuates the increased of atrogenes expression, followed by a functional improvement and gain of skeletal muscle weight, suggesting that HMB protects skeletal muscle against the deleterious effects of fasting.
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Affiliation(s)
- Frederico Gerlinger-Romero
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, 05508-900, Brazil.
- Prédio Biomédicas I-Cidade Universitária-Butantã, Av. Prof. Lineu Prestes 1524, São Paulo, SP, CEP 05508-900, Brazil.
| | - Lucas Guimarães-Ferreira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, 05508-900, Brazil
- Exercise Metabolism Research Group, Department of Sports, Center of Physical Education and Sports, Federal University of Espirito Santo, Vitoria, Brazil
| | - Caio Yogi Yonamine
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, 05508-900, Brazil
| | - Rafael Barrera Salgueiro
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, 05508-900, Brazil
| | - Maria Tereza Nunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, 05508-900, Brazil
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Giovannelli G, Giacomazzi G, Grosemans H, Sampaolesi M. Morphological and functional analyses of skeletal muscles from an immunodeficient animal model of limb-girdle muscular dystrophy type 2E. Muscle Nerve 2018; 58:133-144. [PMID: 29476695 PMCID: PMC6099247 DOI: 10.1002/mus.26112] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2018] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Limb-girdle muscular dystrophy type 2E (LGMD2E) is caused by mutations in the β-sarcoglycan gene, which is expressed in skeletal, cardiac, and smooth muscles. β-Sarcoglycan-deficient (Sgcb-null) mice develop severe muscular dystrophy and cardiomyopathy with focal areas of necrosis. METHODS In this study we performed morphological (histological and cellular characterization) and functional (isometric tetanic force and fatigue) analyses in dystrophic mice. Comparison studies were carried out in 1-month-old (clinical onset of the disease) and 7-month-old control mice (C57Bl/6J, Rag2/γc-null) and immunocompetent and immunodeficient dystrophic mice (Sgcb-null and Sgcb/Rag2/γc-null, respectively). RESULTS We found that the lack of an immunological system resulted in an increase of calcification in striated muscles without impairing extensor digitorum longus muscle performance. Sgcb/Rag2/γc-null muscles showed a significant reduction of alkaline phosphate-positive mesoangioblasts. DISCUSSION The immunological system counteracts skeletal muscle degeneration in the murine model of LGMD2E. Muscle Nerve, 2018.
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Affiliation(s)
- Gaia Giovannelli
- Department of Neurosciences and Imaging“G. d'Annunzio” UniversityChietiItaly
- Translational Cardiomyology, Stem Cell Research InstituteCatholic University of LeuvenHerestraat 49 O&N4–Bus 814LeuvenB‐3000Belgium
| | - Giorgia Giacomazzi
- Translational Cardiomyology, Stem Cell Research InstituteCatholic University of LeuvenHerestraat 49 O&N4–Bus 814LeuvenB‐3000Belgium
| | - Hanne Grosemans
- Translational Cardiomyology, Stem Cell Research InstituteCatholic University of LeuvenHerestraat 49 O&N4–Bus 814LeuvenB‐3000Belgium
| | - Maurilio Sampaolesi
- Translational Cardiomyology, Stem Cell Research InstituteCatholic University of LeuvenHerestraat 49 O&N4–Bus 814LeuvenB‐3000Belgium
- Human Anatomy Unit, Department of Public Health, Experimental and Forensic MedicineUniversity of PaviaPaviaItaly
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Zimowska M, Kasprzycka P, Bocian K, Delaney K, Jung P, Kuchcinska K, Kaczmarska K, Gladysz D, Streminska W, Ciemerych MA. Inflammatory response during slow- and fast-twitch muscle regeneration. Muscle Nerve 2016; 55:400-409. [PMID: 27396429 DOI: 10.1002/mus.25246] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 06/29/2016] [Accepted: 07/07/2016] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Skeletal muscles are characterized by their unique ability to regenerate. Injury of a so-called fast-twitch muscle, extensor digitorum longus (EDL), results in efficient regeneration and reconstruction of the functional tissue. In contrast, slow-twitch muscle (soleus) fails to properly reconstruct and develops fibrosis. This study focuses on soleus and EDL muscle regeneration and associated inflammation. METHODS We determined differences in the activity of neutrophils and M1 and M2 macrophages using flow cytometry and differences in the levels of proinflammatory cytokines using Western blotting and immunolocalization at different times after muscle injury. RESULTS Soleus muscle repair is accompanied by increased and prolonged inflammation, as compared to EDL. The proinflammatory cytokine profile is different in the soleus and ED muscles. CONCLUSIONS Muscle repair efficiency differs by muscle fiber type. The inflammatory response affects the repair efficiency of slow- and fast-twitch muscles. Muscle Nerve 55: 400-409, 2017.
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Affiliation(s)
- Malgorzata Zimowska
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Paulina Kasprzycka
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Katarzyna Bocian
- Department of Immunology, Institute of Zoology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Kamila Delaney
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Piotr Jung
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Kinga Kuchcinska
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Karolina Kaczmarska
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Daria Gladysz
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Wladyslawa Streminska
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
| | - Maria Anna Ciemerych
- Department of Cytology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, 02-096, Warsaw, Poland
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Smith IC, Bellissimo C, Herzog W, Tupling AR. Can inorganic phosphate explain sag during unfused tetanic contractions of skeletal muscle? Physiol Rep 2016; 4:4/22/e13043. [PMID: 27884960 PMCID: PMC5358005 DOI: 10.14814/phy2.13043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 10/31/2016] [Indexed: 12/31/2022] Open
Abstract
We test the hypothesis that cytosolic inorganic phosphate (Pi) can account for the contraction‐induced reductions in twitch duration which impair summation and cause force to decline (sag) during unfused tetanic contractions of fast‐twitch muscle. A five‐state model of crossbridge cycling was used to simulate twitch and unfused tetanic contractions. As Pi concentration ([Pi]) was increased from 0 to 30 mmol·L−1, twitch duration decreased, with progressive reductions in sensitivity to Pi as [Pi] was increased. When unfused tetani were simulated with rising [Pi], sag was most pronounced when initial [Pi] was low, and when the magnitude of [Pi] increase was large. Fast‐twitch extensor digitorum longus (EDL) muscles (sag‐prone, typically low basal [Pi]) and slow‐twitch soleus muscles (sag‐resistant, typically high basal [Pi]) were isolated from 14 female C57BL/6 mice. Muscles were sequentially incubated in solutions containing either glucose or pyruvate to create typical and low Pi environments, respectively. Twitch duration was greater (P < 0.05) in pyruvate than glucose in both muscles. Stimuli applied at intervals approximately three times the time to peak twitch tension resulted in sag of 35.0 ± 3.7% in glucose and 50.5 ± 1.4% in pyruvate in the EDL (pyruvate > glucose; P < 0.05), and 3.9 ± 0.3% in glucose and 37.8 ± 2.7% in pyruvate in the soleus (pyruvate > glucose; P < 0.05). The influence of Pi on crossbridge cycling provides a tenable mechanism for sag. Moreover, the low basal [Pi] in fast‐twitch relative to slow‐twitch muscle has promise as an explanation for the fiber‐type dependency of sag.
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Affiliation(s)
- Ian C Smith
- Human Performance Lab, University of Calgary, Calgary, Alberta, Canada
| | | | - Walter Herzog
- Human Performance Lab, University of Calgary, Calgary, Alberta, Canada
| | - A Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Alves-Wagner AB, Sabino-Silva R, Campello RS, Mori RC, Machado UF. Decreased diabetes-induced glycemic impairment in WKY and SHR involves enhanced skeletal muscle Slc2a4/GLUT4 expression. Diabetol Metab Syndr 2014; 6:97. [PMID: 25228927 PMCID: PMC4164711 DOI: 10.1186/1758-5996-6-97] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 09/04/2014] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Hypertension has been associated to diabetes, and participates in the development of diabetic complications. The spontaneously hypertensive rat (SHR) is the gold standard model for the study of hypertension, and experimental diabetes has been currently investigated in SHR. Wistar-Kyoto rat is usually taken as control for SHR, however, regarding the glycemic homeostasis, WKY may be similar to SHR, when compared to the standard Wistar rat, importantly affecting the interpretation of data. Slc2a4 gene, which encodes the GLUT4 protein, is expressed in insulin-sensitive tissues, such as muscle cells and adipocytes, and alteration in Slc2a4/GLUT4 expression is inversely related to glycemic levels. We investigated the effect of diabetes on the expression of Slc2a4/GLUT4 and glycemic control in Wistar-Kyoto and SHR. FINDINGS Slc2a4 mRNA (Northern-blotting) and GLUT4 protein (Western-blotting) were investigated in skeletal muscles (soleus and extensor digitorum longus) of Wistar, Wistar-Kyoto and SHR, rendered or not diabetic for 1 month. Non-diabetic SHR shows hyperinsulinemia, and unaltered GLUT4 expression. The hyperglycemia was significantly attenuated in diabetic Wistar-Kyoto and SHR, compared to that observed in diabetic Wistar, although all of them presented the same hypoinsulinemic levels. Besides, diabetes significantly reduced Slc2a4/GLUT4 in Wistar, as expected; however, that was not observed in diabetic Wistar-Kyoto and SHR. CONCLUSIONS Non-diabetic SHR is insulin resistant, despite unaltered GLUT4 expression. Diabetic Wistar-Kyoto and diabetic SHR presented high Slc2a4/GLUT4 expression in skeletal muscle, as compared to diabetic Wistar. This Slc2a4/GLUT4 regulation does not depend on insulin level and possibly protects the WKY and SHR from severe glycemic impairment.
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Affiliation(s)
- Ana Barbara Alves-Wagner
- />Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP Brazil
| | - Robinson Sabino-Silva
- />Institute of Biomedical Sciences (ICBIM), Federal University of Uberlandia (UFU), Uberlandia, MG Brazil
| | - Raquel S Campello
- />Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP Brazil
| | - Rosana C Mori
- />Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP Brazil
| | - Ubiratan F Machado
- />Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP Brazil
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Al-Himdani S, Talbot C, Kurdy N, Pillai A. Accessory muscles around the foot and ankle presenting as chronic undiagnosed pain. An illustrative case report and review of the literature. Foot (Edinb) 2013; 23:154-61. [PMID: 24080333 DOI: 10.1016/j.foot.2013.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/12/2013] [Accepted: 08/17/2013] [Indexed: 02/04/2023]
Abstract
The differential diagnosis of ankle pain is extensive. Pathology may be classified as intra- or extra-articular. Additionally, ankle pain may be traumatic or non-traumatic. One of the unusual differential diagnoses for pain in the ankle is an accessory muscle. Magnetic resonance imaging is the radiological investigation of choice. However, this is invariably reported as normal unless one specifically looks for an accessory muscle. The purpose of this report is to highlight important features of these muscles and to draw attention to this uncommonly reported condition.
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Affiliation(s)
- S Al-Himdani
- Department of Trauma and Orthopaedics, University Hospital of South Manchester NHS Foundation Trust, Southmoor Road, Manchester M23 9LT, United Kingdom.
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14
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Zhu Z, Spicer EG, Gavini CK, Goudjo-Ako AJ, Novak CM, Shi H. Enhanced sympathetic activity in mice with brown adipose tissue transplantation (transBATation). Physiol Behav 2013; 125:21-9. [PMID: 24291381 DOI: 10.1016/j.physbeh.2013.11.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/19/2013] [Indexed: 12/22/2022]
Abstract
Brown adipose tissue (BAT) burns calories to produce heat, and is thus relevant to energy balance. Interscapular BAT (IBAT) of donor mice was transplanted into recipient mice (transBATation). To test whether transBATation counteracts high-fat diet (HFD)-induced obesity, some sham-operated and recipient mice were fed a HFD (HFD-sham, HFD-trans) while others remained on a standard chow (chow-sham, chow-trans). HFD-trans mice had lower body weight and fat and greater energy expenditure, but similar caloric intake compared with HFD-sham mice. We hypothesized that HFD-trans mice had elevated sympathetic activity compared with HFD-sham mice, contributing to increased energy expenditure and fuel mobilization. This was supported by findings that HFD-trans mice had greater energy expenditure during a norepinephrine challenge test and higher core temperatures after cold exposure than did HFD-sham mice, implicating enhanced whole-body metabolic response and elevated sympathetic activity. Additionally, transBATation selectively increased sympathetic drive to some, but not all, white adipose tissue depots and skeletal muscles, as well as the endogenous IBAT, heart, and liver. Collectively, transBATation confers resistance to HFD-induced obesity via increase in whole-body sympathetic activity, and differential activation of sympathetic drive to some of the tissues involved in energy expenditure and fuel mobilization.
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Affiliation(s)
- Zheng Zhu
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States; Department of Statistics, Miami University, OH, United States
| | - Elizabeth G Spicer
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States; Department of Nursing, School of Engineering and Applied Sciences, Miami University, OH, United States
| | | | - Ashley J Goudjo-Ako
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States
| | - Colleen M Novak
- Department of Biological Sciences, Kent State University, OH, United States
| | - Haifei Shi
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States.
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15
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Gyorkos AM, McCullough MJ, Spitsbergen JM. Glial cell line-derived neurotrophic factor (GDNF) expression and NMJ plasticity in skeletal muscle following endurance exercise. Neuroscience 2013; 257:111-8. [PMID: 24215980 DOI: 10.1016/j.neuroscience.2013.10.068] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/28/2013] [Accepted: 10/28/2013] [Indexed: 11/26/2022]
Abstract
Glial cell line-derived neurotrophic factor (GDNF) supports and maintains the neuromuscular system during development and through adulthood by promoting neuroplasticity. The aim of this study was to determine if different modes of exercise can promote changes in GDNF expression and neuromuscular junction (NMJ) morphology in slow- and fast-twitch muscles. Rats were randomly assigned to a run training (run group), swim training (swim group), or sedentary control group. GDNF protein content was determined by enzyme-linked immunosorbant assay. GDNF protein content increased significantly in soleus (SOL) following both training protocols (P<0.05). Although not significant, an increase of 60% in the extensor digitorum longus (EDL) followed swim-training (NS; P<0.06). NMJ morphology was analyzed by measuring α-bungarotoxin labeled post-synaptic end plates. GDNF content and total end plate area were positively correlated. End plate area decreased in EDL of the run group and increased in SOL of the swim group. The results indicate that GDNF expression and NMJ morphological changes are activity dependent and that different changes may be observed by varying the exercise intensity in slow- and fast-twitch fibers.
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Affiliation(s)
- A M Gyorkos
- Western Michigan University, Department of Biological Sciences, 1903 West Michigan Avenue, Kalamazoo, MI 49008-5410, USA.
| | - M J McCullough
- Western Michigan University, Department of Biological Sciences, 1903 West Michigan Avenue, Kalamazoo, MI 49008-5410, USA.
| | - J M Spitsbergen
- Western Michigan University, Department of Biological Sciences, 1903 West Michigan Avenue, Kalamazoo, MI 49008-5410, USA.
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16
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Holmström MH, Tom RZ, Björnholm M, Garcia-Roves PM, Zierath JR. Effect of leptin treatment on mitochondrial function in obese leptin-deficient ob/ob mice. Metabolism 2013; 62:1258-67. [PMID: 23664724 DOI: 10.1016/j.metabol.2013.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/15/2013] [Accepted: 04/02/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Leptin stimulates peripheral lipid oxidation, but the influence on mitochondrial function is partly unknown. We investigated tissue-specific mitochondrial function in leptin-deficient obese C57BL/6J-ob/ob mice compared to lean littermates following leptin treatment. MATERIALS AND METHODS Lean and obese ob/ob mice were treated with saline or leptin for 5 days. At day six, liver, extensor digitorum longus (EDL) and soleus muscle were dissected and mitochondrial respiration analyzed in freshly dissected tissues. Expression of key proteins in the regulation of mitochondrial function was determined. RESULTS In liver, mitochondrial respiration was reduced in ob/ob mice compared to lean mice. Expression of mitochondrial transcription factor A (TFAM) was decreased in ob/ob mice, but increased with leptin treatment. In glycolytic EDL muscle, mitochondrial respiration was increased in ob/ob mice. Protein markers of complex II, IV and ATP synthase were increased in EDL muscle from both saline- and leptin-treated ob/ob mice. TFAM protein abundance was decreased, while dynamin-1-like protein was increased in EDL muscle from saline-treated ob/ob mice and restored by leptin treatment. In oxidative soleus muscle, mitochondrial respiration and electron transport system protein abundance were unchanged, while TFAM was reduced in ob/ob mice. CONCLUSIONS In conclusion, leptin-deficient ob/ob mice display tissue-specific mitochondrial adaptations under basal conditions and in response to leptin treatment. Mitochondrial respiration was decreased in liver, increased in glycolytic muscle and unaltered in oxidative muscle from ob/ob mice. Insight into the tissue-specific regulation of mitochondrial function in response to energy supply and demand may provide new opportunities for the treatment of insulin resistance.
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Affiliation(s)
- Maria H Holmström
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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17
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Ringholm S, Olesen J, Pedersen JT, Brandt CT, Halling JF, Hellsten Y, Prats C, Pilegaard H. Effect of lifelong resveratrol supplementation and exercise training on skeletal muscle oxidative capacity in aging mice; impact of PGC-1α. Exp Gerontol 2013; 48:1311-8. [PMID: 23994519 DOI: 10.1016/j.exger.2013.08.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/26/2013] [Accepted: 08/21/2013] [Indexed: 01/05/2023]
Abstract
BACKGROUND The present study tested the hypothesis that lifelong resveratrol (RSV) supplementation counteracts an age-associated decrease in skeletal muscle oxidative capacity through peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α and that RSV combined with lifelong exercise training (EX) exerts additive effects through PGC-1α in mice. METHODS 3 month old PGC-1α whole body knockout (KO) and wild type (WT) littermate mice were placed in cages with or without running wheel and fed either standard chow or standard chow with RSV supplementation (4 g/kg food) for 12 months. Young (3 months of age), sedentary mice on standard chow served as young controls. A graded running performance test and a glucose tolerance test were performed 2 and 1 week, respectively, before euthanization where quadriceps and extensor digitorum longus (EDL) muscles were removed. RESULTS In PGC-1α KO mice, quadriceps citrate synthase (CS) activity, mitochondrial (mt)DNA content as well as pyruvate dehydrogenase (PDH)-E1α, cytochrome (Cyt) c and vascular endothelial growth factor (VEGF) protein content were 20-75% lower and, EDL capillary-to-fiber (C:F) ratio was 15-30% lower than in WT mice. RSV and/or EX had no effect on the C:F ratio in EDL. CS activity (P=0.063) and mtDNA content (P=0.013) decreased with age in WT mice, and CS activity, mtDNA content, PDH-E1α protein and VEGF protein increased ~1.5-1.8-fold with lifelong EX in WT, but not in PGC-1α KO mice, while RSV alone had no significant effect on these proteins. CONCLUSION Lifelong EX increased activity/content of oxidative proteins, mtDNA and angiogenic proteins in skeletal muscle through PGC-1α, while RSV supplementation alone had no effect. Combining lifelong EX and RSV supplementation had no additional effect on skeletal muscle oxidative and angiogenic proteins.
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Affiliation(s)
- Stine Ringholm
- Centre of Inflammation and Metabolism, August Krogh Centre, Department of Biology, August Krogh Building, University of Copenhagen, Denmark
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18
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Ma M. Role of calpains in the injury-induced dysfunction and degeneration of the mammalian axon. Neurobiol Dis 2013; 60:61-79. [PMID: 23969238 DOI: 10.1016/j.nbd.2013.08.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/17/2013] [Accepted: 08/08/2013] [Indexed: 12/21/2022] Open
Abstract
Axonal injury and degeneration, whether primary or secondary, contribute to the morbidity and mortality seen in many acquired and inherited central nervous system (CNS) and peripheral nervous system (PNS) disorders, such as traumatic brain injury, spinal cord injury, cerebral ischemia, neurodegenerative diseases, and peripheral neuropathies. The calpain family of proteases has been mechanistically linked to the dysfunction and degeneration of axons. While the direct mechanisms by which transection, mechanical strain, ischemia, or complement activation trigger intra-axonal calpain activity are likely different, the downstream effects of unregulated calpain activity may be similar in seemingly disparate diseases. In this review, a brief examination of axonal structure is followed by a focused overview of the calpain family. Finally, the mechanisms by which calpains may disrupt the axonal cytoskeleton, transport, and specialized domains (axon initial segment, nodes, and terminals) are discussed.
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Affiliation(s)
- Marek Ma
- Department of Emergency Medicine, University of Pennsylvania, Philadelphia, PA, USA; Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, USA.
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19
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Joassard OR, Amirouche A, Gallot YS, Desgeorges MM, Castells J, Durieux AC, Berthon P, Freyssenet DG. Regulation of Akt-mTOR, ubiquitin-proteasome and autophagy-lysosome pathways in response to formoterol administration in rat skeletal muscle. Int J Biochem Cell Biol 2013; 45:2444-55. [PMID: 23916784 DOI: 10.1016/j.biocel.2013.07.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 07/10/2013] [Accepted: 07/24/2013] [Indexed: 10/26/2022]
Abstract
Administration of β2-agonists triggers skeletal muscle anabolism and hypertrophy. We investigated the time course of the molecular events responsible for rat skeletal muscle hypertrophy in response to 1, 3 and 10 days of formoterol administration (i.p. 2000μg/kg/day). A marked hypertrophy of rat tibialis anterior muscle culminated at day 10. Phosphorylation of Akt, ribosomal protein S6, 4E-BP1 and ERK1/2 was increased at day 3, but returned to control level at day 10. This could lead to a transient increase in protein translation and could explain previous studies that reported increase in protein synthesis following β2-agonist administration. Formoterol administration was also associated with a significant reduction in MAFbx/atrogin-1 mRNA level (day 3), suggesting that formoterol can also affect protein degradation of MAFbx/atrogin1 targeted substrates, including MyoD and eukaryotic initiation factor-3f (eIF3-f). Surprisingly, mRNA level of autophagy-related genes, light chain 3 beta (LC3b) and gamma-aminobutyric acid receptor-associated protein-like 1 (Gabarapl1), as well as lysosomal hydrolases, cathepsin B and cathepsin L, was significantly and transiently increased after 1 and/or 3 days, suggesting that autophagosome formation would be increased in response to formoterol administration. However, this has to be relativized since the mRNA level of Unc-51-like kinase1 (Ulk1), BCL2/adenovirus E1B interacting protein3 (Bnip3), and transcription factor EB (TFEB), as well as the protein content of Ulk1, Atg13, Atg5-Atg12 complex and p62/Sqstm1 remained unchanged or was even decreased in response to formoterol administration. These results demonstrate that the effects of formoterol are mediated, in part, through the activation of Akt-mTOR pathway and that other signaling pathways become more important in the regulation of skeletal muscle mass with chronic administration of β2-agonists.
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Affiliation(s)
- Olivier Roger Joassard
- Laboratoire de Physiologie de l'Exercice, Université de Lyon, F-42023 Saint-Etienne, France
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20
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Baskaran P, Lehmann TE, Topchiy E, Thirunavukkarasu N, Cai S, Singh BR, Deshpande S, Thyagarajan B. Effects of enzymatically inactive recombinant botulinum neurotoxin type A at the mouse neuromuscular junctions. Toxicon 2013; 72:71-80. [PMID: 23810945 DOI: 10.1016/j.toxicon.2013.06.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/10/2013] [Accepted: 06/13/2013] [Indexed: 01/18/2023]
Abstract
Botulinum neurotoxin A (BoNT/A) is used clinically to treat several neurological and metabolic diseases. However, the mechanisms that underlie the clinical use of the toxin remain still to be elusive. BoNT/A inhibits acetylcholine (ACh) release at the motor nerve terminals (MNT) and causes neuroparalysis. The toxic effects of BoNT/A at the MNT occur in sub-pico molar range, and it is invaluable to determine the half-life and the persistence of catalytic activity of the toxin to develop therapeutics against BoNT/A intoxication. However, the use of extremely low concentrations of BoNT/A in cellular, or animal models due to high toxicity makes it difficult to determine new cellular mechanisms and binding or interacting partners of BoNT/A. In order to address this, a catalytically deactivated, non-toxic version of BoNT/A, designated as DrBoNT/A, was characterized. DrBoNT/A lacks endoprotease activity (SNAP-25 cleavage) at concentrations as high as 46,875-fold, compared to wild-type BoNT/A. Unlike BoNT/A injection (3.2 pg), injection of the recombinant product (150 ng or 3.2 pg) into mouse hind limbs failed to cause neuroparalysis as exhibited by the lack of inhibition of toe spread reflex (ability of the mouse to spread its hindlimb toes), and inhibit ACh release at the MNT. The in vitro experiments also demonstrate that DrBoNT/A uptake (at concentrations equivalent to BoNT/A), internalization and localization at the MNT remained unaltered. In addition, modeling studies support that DrBoNT/A lacked the zinc binding ability, and the ability to directly participate in the hydrolysis of SNAP-25 substrate. Collectively, we demonstrate that DrBoNT/A is non-toxic to the MNT and can be used as a surrogate tool to understand the mechanism by which BoNT/A modulates signal transduction mechanisms.
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21
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Schakman O, Kalista S, Barbé C, Loumaye A, Thissen JP. Glucocorticoid-induced skeletal muscle atrophy. Int J Biochem Cell Biol 2013; 45:2163-72. [PMID: 23806868 DOI: 10.1016/j.biocel.2013.05.036] [Citation(s) in RCA: 384] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 05/27/2013] [Accepted: 05/29/2013] [Indexed: 12/11/2022]
Abstract
Many pathological states characterized by muscle atrophy (e.g., sepsis, cachexia, starvation, metabolic acidosis and severe insulinopenia) are associated with an increase in circulating glucocorticoids (GC) levels, suggesting that GC could trigger the muscle atrophy observed in these conditions. GC-induced muscle atrophy is characterized by fast-twitch, glycolytic muscles atrophy illustrated by decreased fiber cross-sectional area and reduced myofibrillar protein content. GC-induced muscle atrophy results from increased protein breakdown and decreased protein synthesis. Increased muscle proteolysis, in particular through the activation of the ubiquitin proteasome and the lysosomal systems, is considered to play a major role in the catabolic action of GC. The stimulation by GC of these two proteolytic systems is mediated through the increased expression of several Atrogenes ("genes involved in atrophy"), such as FOXO, Atrogin-1, and MuRF-1. The inhibitory effect of GC on muscle protein synthesis is thought to result mainly from the inhibition of the mTOR/S6 kinase 1 pathway. These changes in muscle protein turnover could be explained by changes in the muscle production of two growth factors, namely Insulin-like Growth Factor (IGF)-I, a muscle anabolic growth factor and Myostatin, a muscle catabolic growth factor. This review will discuss the recent progress made in the understanding of the mechanisms involved in GC-induced muscle atrophy and consider the implications of these advancements in the development of new therapeutic approaches for treating GC-induced myopathy. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.
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Abstract
Skeletal muscle loss appears to be the most significant clinical event in cancer cachexia and is associated with a poor outcome. With regard to such muscle loss, despite extensive study in a range of models, there is ongoing debate as to whether a reduction in protein synthesis, an increase in degradation or a combination of both is the more relevant. Each model differs in terms of key mediators and the pathways activated in skeletal muscle. Certain models do suggest that decreased synthesis accompanied by enhanced protein degradation via the ubiquitin proteasome pathway (UPP) is important. Murine models tend to involve rapid development of cachexia and may represent more acute muscle atrophy rather than the chronic wasting observed in humans. There is a paucity of human data both at a basic descriptive level and at a molecular/mechanism level. Progress in treating the human form of cancer cachexia can only move forwards through carefully designed large randomised controlled clinical trials of specific therapies with validated biomarkers of relevance to underlying mechanisms. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.
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Affiliation(s)
- N Johns
- Department of Clinical and Surgical Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
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23
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Saheb-Al-Zamani M, Yan Y, Farber SJ, Hunter DA, Newton P, Wood MD, Stewart SA, Johnson PJ, Mackinnon SE. Limited regeneration in long acellular nerve allografts is associated with increased Schwann cell senescence. Exp Neurol 2013; 247:165-77. [PMID: 23644284 DOI: 10.1016/j.expneurol.2013.04.011] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 04/22/2013] [Accepted: 04/25/2013] [Indexed: 12/25/2022]
Abstract
Repair of large nerve defects with acellular nerve allografts (ANAs) is an appealing alternative to autografting and allotransplantation. ANAs have been shown to be similar to autografts in supporting axonal regeneration across short gaps, but fail in larger defects due to a poorly-understood mechanism. ANAs depend on proliferating Schwann cells (SCs) from host tissue to support axonal regeneration. Populating longer ANAs places a greater proliferative demand on host SCs that may stress host SCs, resulting in senescence. In this study, we investigated axonal regeneration across increasing isograft and ANA lengths. We also evaluated the presence of senescent SCs within both graft types. A sciatic nerve graft model in rats was used to evaluate regeneration across increasing isograft (~autograft) and ANA lengths (20, 40, and 60 mm). Axonal regeneration and functional recovery decreased with increased graft length and the performance of the isograft was superior to ANAs at all lengths. Transgenic Thy1-GFP rats and qRT-PCR demonstrated that failure of the regenerating axonal front in ANAs was associated with increased levels of senescence related markers in the graft (senescence associated β-galactosidase, p16(INK4A), and IL6). Lastly, electron microscopy (EM) was used to qualitatively assess senescence-associated changes in chromatin of SCs in each graft type. EM demonstrated an increase in the presence of SCs with abnormal chromatin in isografts and ANAs of increasing graft length. These results are the first to suggest that SC senescence plays a role in limited axonal regeneration across nerve grafts of increasing gap lengths.
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Affiliation(s)
- Maryam Saheb-Al-Zamani
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Ying Yan
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Scott J Farber
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Daniel A Hunter
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Piyaraj Newton
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Matthew D Wood
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Sheila A Stewart
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8228, St. Louis, MO 63110, USA
| | - Philip J Johnson
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
| | - Susan E Mackinnon
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8238, St. Louis, MO 63110, USA
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van Lunteren E, Moyer M. The Effects of K(+) Channel Blockade on Eccentric and Isotonic Twitch and Fatiguing Contractions in situ. Front Physiol 2012; 3:383. [PMID: 23060809 PMCID: PMC3460371 DOI: 10.3389/fphys.2012.00383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/08/2012] [Indexed: 11/16/2022] Open
Abstract
K(+) channel blockers like 3,4-diaminopyridine (DAP) can double isometric muscle force. Functional movements require more complex concentric and eccentric contractions, however the effects of K(+) channel blockade on these types of contractions in situ are unknown. Extensor digitorum longus (EDL) muscles were stimulated in situ with and without DAP in anesthetized rats and fatigability was addressed using a series of either concentric or eccentric contractions. During isotonic protocols (5-100% load), DAP significantly shifted shortening- and maximum shortening velocity-load curves upward and to the right and increased power and work. Maximum shortening, maximum shortening velocity, and power doubled while work increased by ∼250% during isotonic contraction at 50% load. During isotonic fatigue, DAP significantly augmented maximum shortening, work, shortening velocity, and power. During constant velocity eccentric protocols (2-12 mm/s), DAP increased muscle force during eccentric contractions at 6, 8, 10, and 12 mm/s. During eccentric contraction at a constant velocity of 6 mm/s while varying the stimulation frequency, DAP significantly increased muscle force during 20, 40, and 70 Hz. The effects of DAP on muscle contractile performance during eccentric fatigue varied with level of fatigue. DAP-induced contractile increases during isotonic contractions were similar to those produced during previously studied isometric contractions, while the DAP effect during eccentric contractions was more modest. These findings are especially important in attempting to optimize functional electrical stimulation parameters for spinal cord injury patients while also preventing rapid fatigue of those muscles.
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Affiliation(s)
- Erik van Lunteren
- Pulmonary, Critical Care and Sleep Division, Department of Medicine, Cleveland VA Medical Center, Case Western Reserve UniversityCleveland, OH, USA
| | - Michelle Moyer
- Pulmonary, Critical Care and Sleep Division, Department of Medicine, Cleveland VA Medical Center, Case Western Reserve UniversityCleveland, OH, USA
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