jocb

• Larssen, Thomas; Glesaaen, Ole Jørgen; Bruusgaard, Jo Christiansen; Strand, Martin Frank; Kalhovde, John Magne & Tønnessen, Espen [Vis alle 7 forfattere av denne artikkelen] (2025). A comparative study of lactate threshold testing outcomes: walking vs. running. Journal of Sports Medicine and Physical Fitness. ISSN 0022-4707. 65(10), s. 1330–1336. doi: 10.23736/s0022-4707.25.17054-0. Fulltekst i vitenarkiv Vis sammendrag

  Background Although lactate threshold (LT) tests are widely used by athletes to evaluate endurance performance, such tests are not commonly applied in health controls among recreationally active subjects. This study aimed to investigate the test-retest reliability of walking as an exercise modality during LT testing and compare the test outcomes with those obtained during running. Methods Twenty-three male and female participants (25±3 year, 172±8 cm, 70±13 kg, and maximal oxygen consumption [VO2max] 51±5 mL·kg-1·min-1) performed four LT tests within 2-3 weeks, either using walking or running (two tests in each condition) protocols. The running tests were performed on a flat treadmill, and the pace increased by 1 km·h-1 for each stage. During the walking tests, the pace was set to 6.5 km·h-1, and the incline increased by 2.5% for each stage. LT was determined based on a fixed blood lactate concentration of 4.0 mmol·L-1. Results Similar reliability values were observed for the walking and running protocol, and all between-trial differences were trivial or small. Significantly lower heart rate at LT was observed for the walking vs. running condition, but all between-modality differences were trivial or small. Analysis revealed that LT occurred at a slightly lower workload in walking than running (11.4±1.4 vs. 12.0±1.3 metabolic equivalents [METs]). Conclusions Given the trivial to small differences in LT variables observed between running and walking, these two protocols cannot be used interchangeably. However, the present study shows that walking represents an alternative exercise modality during LT testing in recreationally active subjects.

• Sigvaldsen, Eirik Saxegaard; Loturco, Irineu; Larsen, Fredrik; Bruusgaard, Jo Christiansen; Kalhovde, John Magne & Haugen, Thomas André (2023). Validity and reliability of upper body push and pull tests to determine one-repetition maximum. PLOS ONE. 18(7). doi: 10.1371/journal.pone.0288649. Fulltekst i vitenarkiv
• Hansson, Kenth-Arne; Eftestøl, Einar; Bruusgaard, Jo C.; Juvkam, Inga; Cramer, Alyssa W. & Malthe-Sørenssen, Anders [Vis alle 8 forfattere av denne artikkelen] (2020). Myonuclear content regulates cell size with similar scaling properties in mice and humans. Nature Communications. 11(1). doi: 10.1038/s41467-020-20057-8. Fulltekst i vitenarkiv Vis sammendrag

  Muscle fibers are the largest cells in the body, and one of its few syncytia. Individual cell sizes are variable and adaptable, but what governs cell size has been unclear. We find that muscle fibers are DNA scarce compared to other cells, and that the nuclear number (N) adheres to the relationship N = aVb where V is the cytoplasmic volume. N invariably scales sublinearly to V (b < 1), making larger cells even more DNA scarce. N scales linearly to cell surface in adult humans, in adult and developing mice, and in mice with genetically reduced N, but in the latter the relationship eventually fails when they reach adulthood with extremely large myonuclear domains. Another exception is denervation-atrophy where nuclei are not eliminated. In conclusion, scaling exponents are remarkably similar across species, developmental stages and experimental conditions, suggesting an underlying scaling law where DNA-content functions as a limiter of muscle cell size.

• Hansson, Kenth-Arne; Solbrå, Andreas Våvang; Gundersen, Kristian & Bruusgaard, Jo C. (2020). Computational assessment of transport distances in living skeletal muscle fibers studied in situ. Biophysical Journal. ISSN 0006-3495. 119(11), s. 2166–2178. doi: 10.1016/j.bpj.2020.10.016. Fulltekst i vitenarkiv
• Psilander, Niklas; Eftestøl, Einar; Cumming, Kristoffer Toldnes; Solgård, Inga Juvkam; Ekblom, Maria M. & Sunding, Kerstin [Vis alle 12 forfattere av denne artikkelen] (2019). Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle. Journal of applied physiology. ISSN 8750-7587. 126(6), s. 1636–1645. doi: 10.1152/japplphysiol.00917.2018. Fulltekst i vitenarkiv Vis sammendrag

  Previously trained mouse muscles acquire strength and volume faster than naïve muscles; it has been suggested that this is related to increased myonuclear density. The present study aimed to determine whether a previously strength-trained leg (mem-leg) would respond better to a period of strength training than a previously untrained leg (con-leg). Nine men and 10 women performed unilateral strength training (T1) for 10 wk, followed by 20 wk of detraining (DT) and a 5-wk bilateral retraining period (T2). Muscle biopsies were taken before and after each training period and analyzed for myonuclear number, fiber volume, and cross-sectional area (CSA). Ultrasound and one repetition of maximum leg extension were performed to determine muscle thickness (MT) and strength. CSA (~17%), MT (~10%), and strength (~20%) increased during T1 in the mem-leg. However, the myonuclear number and fiber volume did not change. MT and CSA returned to baseline values during DT, but strength remained elevated (~60%), supporting previous findings of a long-lasting motor learning effect. MT and strength increased similarly in the mem-leg and con-leg during T2, whereas CSA, fiber volume, and myonuclear number remained unaffected. In conclusion, training response during T2 did not differ between the mem-leg and con-leg. However, this does not discount the existence of human muscle memory, since no increase in the number of myonuclei was detected during T1 and no clear detraining effect was observed for cell size during DT; thus, the present data did not allow for a rigorous test of the muscle memory hypothesis.

• Gundersen, Kristian; Bruusgaard, Jo C.; Egner, Ingrid Marie; Eftestøl, Einar & Bengtsen, Mads (2018). Muscle memory: virtues of your youth? Journal of Physiology. ISSN 0022-3751. 596(18), s. 4289–4290. doi: 10.1113/JP276354. Fulltekst i vitenarkiv
• Winje, Ivan; Sheng, Xia; Hansson, Kenth-Arne; Solbrå, Andreas Våvang; Tennøe, Simen & Saatcioglu, Fahri [Vis alle 8 forfattere av denne artikkelen] (2018). Cachexia does not induce loss of myonuclei or muscle fibres during xenografted prostate cancer in mice. Acta Physiologica. ISSN 1748-1708. s. 1–9. doi: 10.1111/apha.13204. Fulltekst i vitenarkiv
• Winje, Ivan; Bengtsen, Mads; Eftestøl, Einar; Juvkam, Inga; Bruusgaard, Jo C. & Gundersen, Kristian (2018). Specific labelling of myonuclei by an antibody against pericentriolar material 1 on skeletal muscle tissue sections. Acta Physiologica. ISSN 1748-1708. 223(4), s. 1–9. doi: 10.1111/apha.13034. Fulltekst i vitenarkiv Vis sammendrag

  Aim: Skeletal muscle is a heterogeneous tissue containing several different cell types, and only about 40%‐50% of the cell nuclei within the tissue belong to myofibres. Existing technology, attempting to distinguish myonuclei from other nuclei at the light microscopy level, has led to controversies in our understanding of the basic cell biology of muscle plasticity. This study aims at demonstrating that an antibody against the protein pericentriolar material 1 (PCM1) can be used to reliably identify myonuclei on histological cross sections from humans, mice and rats. Methods: Cryosections were labelled with a polyclonal antibody against PCM1. The specificity of the labelling for myonuclei was verified using 3D reconstructions of confocal z‐stacks triple‐labelled for DNA, dystrophin and PCM1, and by co‐localization with nuclear mCherry driven by the muscle‐specific Alpha‐Actin‐1 promoter after viral transduction. Results: The PCM1 antibody specifically labelled all myonuclei, and myonuclei only, in cryosections of muscles from rats, mice and men. Nuclei in other cell types including satellite cells were not labelled. Both normal muscles and hypertrophic muscles after synergist ablation were investigated. Conclusion: Pericentriolar material 1 can be used as a specific histological marker for myonuclei in skeletal muscle tissue without relying on counterstaining of other structures or cumbersome and subjective analysis of nuclear positioning.

• Bakke, Marit Jørgensen; Agusti-Ridaura, Celia; Bruusgaard, Jo C.; Sundaram, Arvind Yegambaram Meenakshi & Horsberg, Tor Einar (2018). Deltamethrin resistance in the salmon louse, Lepeophtheirus salmonis (Krøyer): Maternal inheritance and reduced apoptosis. Scientific Reports. 8. doi: 10.1038/s41598-018-26420-6. Fulltekst i vitenarkiv Vis sammendrag

  Resistance towards deltamethrin (DMT) in the crustacean ectoparasite Lepeophtheirus salmonis (Caligidae) is a problem on fish farms lining the North Atlantic Ocean. Two Norwegian strains with different susceptibility towards DMT were crossed in the parental generation (P0), females from a sensitive strain were crossed with males from a resistant strain and vice versa. Individual susceptibility towards DMT was assessed in the second filial generation (F2). DMT resistance was only found in F2 descendants when the P0 females were from the resistant strain, pointing to maternal inheritance. Since maternal inheritance might be linked to the mitochondrial (mt) genome, the nucleotide sequences and the gene expressions of mt-genes were analysed. Twenty non-synonymous single nucleotide polymorphisms (SNPs) were identified in mt-transcripts from resistant F2 parasites, including SNPs in two cytochrome C oxidase subunits (COX1 and COX3) and two subunits of the NADH dehydrogenase complex (ND1 and ND5) previously linked to DMT resistance in the salmon louse. Differential expression analysis between the sensitive and resistant strain revealed strain effect in seven out of twelve mt-genes. The current study also show that DNA fragmentation (indicating apoptosis) was affected by DMT exposure in skeletal muscle tissue and that resistant parasites undergo less apoptosis than sensitive parasites.

• Egner, Ingrid Marie; Bruusgaard, Jo C. & Gundersen, Kristian (2016). Satellite cell depletion prevents fiber hypertrophy in skeletal muscle. Development. ISSN 0950-1991. 143(16), s. 2898–2906. doi: 10.1242/dev.134411. Fulltekst i vitenarkiv
• Omairi, Saleh; Matsakas, Antonios; Degens, Hans; Kretz, Oliver; Hansson, Kenth-Arne & Solbrå, Andreas Våvang [Vis alle 20 forfattere av denne artikkelen] (2016). Enhanced exercise and regenerative capacity in a mouse model that violates size constraints of oxidative muscle fibres. eLIFE. 5(AUGUST). doi: 10.7554/eLife.16940. Fulltekst i vitenarkiv
• Eftestøl, Einar; Egner, Ingrid Marie; Lunde, Ida Gjervold; Ellefsen, Stian; Andersen, Tom & Sjåland, Cecilie [Vis alle 8 forfattere av denne artikkelen] (2016). Increased hypertrophic response with increased mechanical load in skeletal muscles receiving identical activity patterns. American Journal of Physiology - Cell Physiology. 311(4), s. C616–C629. doi: 10.1152/ajpcell.00016.2016. Fulltekst i vitenarkiv
• Eftestøl, Einar; Alver, Tine Norman; Gundersen, Kristian & Bruusgaard, Jo C. (2014). Overexpression of SMPX in adult skeletal muscle does not change skeletal muscle fiber type or size. PLOS ONE. 9(6). doi: 10.1371/journal.pone.0099232. Fulltekst i vitenarkiv Vis sammendrag

  Mechanical factors such as stretch are thought to be important in the regulation of muscle phenotype. Small muscle protein X-linked (SMPX) is upregulated by stretch in skeletal muscle and has been suggested to serve both as a transcription factor and a mechanosensor, possibly giving rise to changes in both fiber size and fiber type. We have used in vivo confocal imaging to study the subcellular localization of SMPX in skeletal muscle fibers of adult rats using a SMPX-EGFP fusion protein. The fusion protein was localized predominantly in repetitive double stripes flanking the Z-disc, and was excluded from all nuclei. This localization would be consistent with SMPX being a mechanoreceptor, but not with SMPX playing a role as a transcription factor. In vivo overexpression of ectopic SMPX in skeletal muscle of adult mice gave no significant changes in fiber type distribution or cross sectional area, thus a role of SMPX in regulating muscle phenotype remains unclear.

• Løvås, Tom-Ole; Bruusgaard, Jo C.; Øynebråten, Inger; Gundersen, Kristian & Bogen, Bjarne (2014). DNA vaccines: MHC II-targeted vaccine protein produced by transfected muscle fibres induces a local inflammatory cell infiltrate in mice. PLOS ONE. 9(10). doi: 10.1371/journal.pone.0108069. Fulltekst i vitenarkiv Vis sammendrag

  Vaccination with naked DNA holds great promise but immunogenicity needs to be improved. DNA constructs encoding bivalent proteins that bind antigen-presenting cells (APC) for delivery of antigen have been shown to enhance T and B cell responses and protection in tumour challenge experiments. However, the mechanism for the increased potency remains to be determined. Here we have constructed DNA vaccines that express the fluorescent protein mCherry, a strategy which allowed tracking of vaccine proteins. Transfected muscle fibres in mice were visualized, and their relationship to infiltrating mononuclear cells could be determined. Interestingly, muscle fibers that produced MHC class II-specific dimeric vaccine proteins with mCherry were for weeks surrounded by a localized intense cellular infiltrate composed of CD45+, MHC class II+ and CD11b+ cells. Increasing numbers of eosinophils were observed among the infiltrating cells from day 7 after immunization. The local infiltrate surrounding mCherry+ muscle fibers was dependent on the MHC II-specificity of the vaccine proteins since the control, a non-targeted vaccine protein, failed to induce similar infiltrates. Chemokines measured on day 3 in immunized muscle indicate both a DNA effect and an electroporation effect. No influence of targeting was observed. These results contribute to our understanding for why targeted DNA vaccines have an improved immunogenicity.

• Egner, Ingrid Marie; Bruusgaard, Jo C.; Eftestøl, Einar & Gundersen, Kristian (2013). A cellular memory mechanism aids overload hypertrophy in muscle long after an episodic exposure to anabolic steroids. Journal of Physiology. ISSN 0022-3751. 591(24), s. 6221–6230. doi: 10.1113/jphysiol.2013.264457. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Egner, Ingrid Marie; Klungervik, Tove; Dupre-Aucouturier, S; Desplanches, D & Gundersen, Kristian (2012). No change in myonuclear number during muscle unloading and reloading. Journal of applied physiology. ISSN 8750-7587. 113(2), s. 290–296. doi: 10.1152/japplphysiol.00436.2012. Fulltekst i vitenarkiv
• Lunde, Ida Gjervold; Anton, Siobhan Lisa; Bruusgaard, Jo C.; Rana, Zaheer Ahmad; Ellefsen, Stian & Gundersen, Kristian (2011). Hypoxia inducible factor 1α links fast-patterned muscle activity and fast muscle phenotype in rats. Journal of Physiology. ISSN 0022-3751. 589(6), s. 1443–1454. doi: 10.1113/jphysiol.2010.202762. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Johansen, Ida Beitnes; Egner, Ingrid Marie; Rana, Zaheer Ahmad & Gundersen, Kristian (2010). Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 107(34), s. 15111–15116. doi: 10.1073/pnas.0913935107. Fulltekst i vitenarkiv
• Gundersen, Kristian & Bruusgaard, Jo C. (2008). Nuclear domains during muscle atrophy: nuclei lost or paradigm lost? Journal of Physiology. ISSN 0022-3751. 586. doi: 10.1113/jphysiol.2008.154369. Fulltekst i vitenarkiv
• Bruusgaard, Jo C. & Gundersen, Kristian (2008). In vivo time-lapse microscopy reveals no loss of murine myonuclei during weeks of muscle atrophy. Journal of Clinical Investigation. ISSN 0021-9738. 118. doi: 10.1172/JCI34022. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Liestøl, Knut & Gundersen, Kristian (2006). Distribution of myonuclei and microtubules in live muscle fibers of young, middle-aged, and old mice. Journal of applied physiology. ISSN 8750-7587. 100, s. 2024–2030. Fulltekst i vitenarkiv
• Bedet, Ceclie; Bruusgaard, Jo C.; Vergo, Stephanie; Groth-Pedersen, Line; Eimer, Stephan & Triller, Antoine [Vis alle 7 forfattere av denne artikkelen] (2006). Regulation of gephyrin assembly and glycine receptor synaptic stability. Journal of Biological Chemistry. ISSN 0021-9258. 281(40), s. 30046–30056. Fulltekst i vitenarkiv Vis sammendrag

  Gephyrin is required for the formation of clusters of the glycine receptor (GlyR) in the neuronal postsynaptic membrane. It can make trimers and dimers through its N- and C-terminal G and E domains, respectively. Gephyrin oligomerization could thus create a submembrane lattice providing GlyR-binding sites. We investigated the relationships between the stability of cell surface GlyR and the ability of gephyrin splice variants to form oligomers. Using truncated and full-length gephyrins we found that the 13-amino acid sequence (cassette 5) prevents G domain trimerization. Moreover, E domain dimerization is inhibited by the gephyrin central L domain. All of the gephyrin variants bind GlyR beta subunit cytoplasmic loop with high affinity regardless of their cassette composition. Coexpression experiments in COS-7 cells demonstrated that GlyR bound to gephyrin harboring cassette 5 cannot be stabilized at the cell surface. This gephyrin variant was found to deplete synapses from both GlyR and gephyrin in transfected neurons. These data suggest that the relative expression level of cellular variants influence the overall oligomerization pattern of gephyrin and thus the turnover of synaptic GlyR.

• Bruusgaard, Jo C.; Brack, AS; Hughes, SM & Gundersen, Kristian (2005). Muscle hypertrophy induced by the Ski protein: cyto-architecture and ultrastructure. Acta Physiologica Scandinavica. ISSN 0001-6772. 185(2), s. 141–149. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Liestøl, Knut; Ekmark, Merete; Kollstad, K & Gundersen, Kristian (2003). Number and spatial distribution of nuclei in the muscle fibres of normal mice studied in vivo. Journal of Physiology. ISSN 0022-3751. 551(2), s. 467–478. Fulltekst i vitenarkiv

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• Strand, Martin Frank; Fredriksen, Per Morten & Bruusgaard, Jo Christiansen (2024). Mange barn og unge har for lite jern i kosten. Kunnskapsmagasinet Kristiania. Fulltekst i vitenarkiv
• Bruusgaard, Jo Christiansen & Strand, Martin Frank (2023). Dobbeltjubileum på DNA-dagen! Og noen betenkeligheter. Kunnskapsmagasinet Kristiania. Fulltekst i vitenarkiv
• Eftestøl, Einar & Bruusgaard, Jo C. (2021). Long-lasting cellular imprinting. Performance hacking towards the Olympics? Physiology News. 1222, s. 34–36. Fulltekst i vitenarkiv
• Eftestøl, Einar; Psilander, Niklas; Cumming, Kristoffer Toldnes; Juvkam, Inga; Ekblom, Maria M. & Sunding, Kerstin [Vis alle 12 forfattere av denne artikkelen] (2019). Muscle memory: Are myonuclei ever lost? Journal of applied physiology. ISSN 8750-7587. 128(2), s. 456–457. doi: 10.1152/japplphysiol.00761.2019. Fulltekst i vitenarkiv
• Hansson, Kenth-Arne; Gundersen, Kristian & Bruusgaard, Jo C. (2018). In vivo confocal imaging and 3D rendering of the neuromuscular end plate and its synaptic myonuclei. Acta Physiologica. ISSN 1748-1708. Fulltekst i vitenarkiv
• Benestad, Haakon Breien; Sand, Kristin Larsen & Bruusgaard, Jo C. (2018). Less than recommended training of aerobic fitness and muscle strength: What to expect? Acta Physiologica. ISSN 1748-1708. 224(4). doi: 10.1111/apha.13104. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Kalhovde, John Magne; Paulsen, Gøran; Sefland, Iren; Støve, Kjersti & Raastad, Truls (2018). Tetranectin labels myofibrillar disruptions after eccentric exercise in humans. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. doi: 10.1007/s10974-016-9457-1. Fulltekst i vitenarkiv
• Egner, Ingrid Marie; Bruusgaard, Jo C. & Gundersen, Kristian (2017). An apparent lack of effect of satellite cell depletion on hypertrophy could be due to methodological limitations. Response to `Methodological issues limit interpretation of negative effects of satellite cell depletion on adult muscle hypertrophy? Development. ISSN 0950-1991. 144(8), s. 1365–1367. doi: 10.1242/dev.148163. Fulltekst i vitenarkiv
• Jensenius, Alexander Refsum; Bjerkestrand, Kari Anne Vadstensvik; Donnarumma, Marco; Brean, Are & Bruusgaard, Jo C. (2017). Panel: Biophysical Music. Fulltekst i vitenarkiv Vis sammendrag

  "Biophysical Music" is volume 1 of the new concept "MusicLab", a series of events exploring the science of music from different perspectives. The idea is to mix research and edutainment through hands-on workshops, intellectual warm-ups, performances and data jockeying.

• Eftestøl, Einar; Egner, Ingrid Marie; Ellefsen, Stian; Andersen, Tom; Gundersen, Kristian & Bruusgaard, Jo C. (2016). The importance of mechanosensation in skeletal muscle hypertrophy. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Kalhovde, John Magne; Raastad, Truls; Paulsen, Gøran; Støve, Kjersti & Sefland, Iren (2016). Tetranectin labels myofibrillar disruptions after eccentric exercise in humans. Fulltekst i vitenarkiv
• Bruusgaard, Jo C. & Gundersen, Kristian (2014). Musklene dine kan huske. Fulltekst i vitenarkiv
• Eftestøl, Einar; Bruusgaard, Jo C. & Gundersen, Kristian (2012). The contraction duration is not important for hypertrophy in strength trained rats. Fulltekst i vitenarkiv
• Egner, Ingrid Marie; Bruusgaard, Jo C.; Eftestøl, Einar & Gundersen, Kristian (2012). Effects of anabolic steroid on nuclear number and muscle mass. Fulltekst i vitenarkiv
• Anton, Siobhan Lisa; Bruusgaard, Jo C. & Gundersen, Kristian (2011). In vivo knockdown of myogenin leads to a faster muscle phenotype. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 32, s. 345–346. doi: 10.1007/s10974-011-9265-6. Fulltekst i vitenarkiv
• Gundersen, Kristian; Eftestøl, Einar; Egner, Ingrid Marie & Bruusgaard, Jo C. (2011). The effect of testosterone propionate on overloaded skeletal muscle. Fulltekst i vitenarkiv
• Anton, Siobhan Lisa; Bruusgaard, Jo C. & Gundersen, Kristian (2011). In Vivo Knockdown of Myogenin Leads to a Faster Muscle Phenotype. Fulltekst i vitenarkiv
• Anton, Siobhan Lisa; Lunde, Ida Gjervold; Bruusgaard, Jo C. & Gundersen, Kristian (2010). HIF-1a regulates the oxidative capacity of adult rat skeletal muscle. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 32, s. 136–136. doi: 10.1007/s10974-011-9257-6. Fulltekst i vitenarkiv
• Anton, Siobhan Lisa; Lunde, Ida Gjervold; Bruusgaard, Jo C. & Gundersen, Kristian (2010). HIF-1a regulates the oxidative capacity of adult rat skeletal muscle. Fulltekst i vitenarkiv
• Hansen, Einar Eftestøl Holm; Bruusgaard, Jo C. & Gundersen, Kristian (2009). What is the role of SMPX in skeletal muscle? Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 129(1), s. 329–329. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Johansen, Ida Beitnes; Egner, Ingrid Marie & Gundersen, Kristian (2009). Are myonuclei forever? Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 30(1), s. 307–307. Fulltekst i vitenarkiv
• Lunde, Ida Gjervold; Bruusgaard, Jo C. & Gundersen, Kristian (2009). HIF-1a regulates fast MyHC expression in skeletal muscle of normally active adult rats. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 129(1), s. 328–328. Fulltekst i vitenarkiv
• Brandtzæg, Per; Bruusgaard, Jo C. & Gundersen, Kristian (2009). Djevelens advokat i Snåsa. Morgenbladet. ISSN 0805-3847. Fulltekst i vitenarkiv
• Brandtzæg, Per; Bruusgaard, Jo C. & Gundersen, Kristian (2009). Lemfeldig observasjon. Morgenbladet. ISSN 0805-3847. Fulltekst i vitenarkiv
• Bruusgaard, Jo C. (2009). Brainbow – hjerneforskning med manetproteiner. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 129(1). Fulltekst i vitenarkiv
• Brandtzæg, Per; Bruusgaard, Jo C. & Gundersen, Kristian (2008). Tvilsom bevisvurdering. Morgenbladet. ISSN 0805-3847. Fulltekst i vitenarkiv
• Bruusgaard, Jo C. & Gundersen, Kristian (2007). No loss of myonuclei after inactivity-induced skeletal muscle atrophy. Acta Physiologica Scandinavica. ISSN 0001-6772. Fulltekst i vitenarkiv Vis sammendrag

  OBJECTIVE: The skeletal muscle cells are the largest cells in the mammalian body, and are one of few syncytia in mammals. Both in man and in animals it has been widely accepted that muscle cell size is correlated, and perhaps even causally related, to the number of myonuclei. Thus, it is assumed that hypertrophy involves incorporation of new nuclei from satellite cells, and that atrophy involves loss of nuclei by apoptosis. METHODS: Mice were denervated or neural transmission was blocked using TTX for up to 24 days, and stained in vivo using either intracellular injection of fluorescent oligonucleotides, or transfection with a plasmid encoding EGFP with a nuclear localization signal. Apoptotic nuclei were detected using TdT-labeling of fragmented DNA. RESULTS: After denervation up to 24 days there was no loss of myonuclei in neither the EDL nor solei muscles. We found the number of myonuclei per mm to be 52.95±1.7 (before denervation), vs. 54.31±2,8 (after denervation) in the EDL, and in the soleus 71.94±2.9 vs. 74.56±3.9, in spite of a reduction in cross sectional area of more than 50%. TTX block of the sciatic nerve yielded similar results. Apoptotic nuclei were found in the atrophying muscle tissue, but none of these were identified as belonging to muscle fibers. CONCLUSION: The classical idea of a constant karyoplasmatic ratio cannot be maintained for denervation atrophy. We confirm that in the first period after denervation, muscle tissue is undergoing atrophy and an active period of apoptosis, but the loss of cell nuclei by apoptosis seems to be confined to stroma and satellite cells.

• Bruusgaard, Jo C. & Gundersen, Kristian (2006). Muscle atrophy is not accompanied by loss of myonuclei. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 27(5-7), s. 533–533. Fulltekst i vitenarkiv
• Bruusgaard, Jo C.; Brack, Andrew; Hughes, Simon & Gundersen, Kristian (2004). Ultrastrucural changes in young mice expressing the MSVski proto-oncogene. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 25, s. 268–268. Fulltekst i vitenarkiv Vis sammendrag

  Mice carrying the MSVski proto-oncogene undergo muscle hypertrophy. This effect has been attributed to decreased protein breakdown possibly as a result of TGF-b signaling. The muscle fibers of these animals exhibit a reduced specific force (N/mm2) when compared to normal animals. This led us to investigate the ultrastructure of young ski mice using electron microscopy, in order to expose whether there might be a reduction in the relative amount of contractile apparatus. We also used in vivo injections of myonuclear dyes to investigate nuclear number. The study revealed enlarged mitochondria with disintegrated or damaged cristae, disrupted z-discs and a significantly larger amount of non-contractile area. The increase in nuclear number accompanying hypertrophy seen in normal mice was also absent. These findings could explain the lower specific force, as well as indicating a non-myosin related effect of the ski protein.

• Bruusgaard, Jo C.; Liestøl, Knut; Ekmark, Merete; Kollstad, Kjetil & Gundersen, Kristian (2003). Number and spatial distribution of nuclei in muscle fibers of normal mice studied in vivo. Journal of Muscle Research and Cell Motility. ISSN 0142-4319. 24, s. 326–326. Fulltekst i vitenarkiv
• Utvik, Jo Kristian; Ashtari, Ohmid; Bruusgaard, Jo C.; Bezakova, Gabriela; Mathiesen, Iacob & Lømo, Terje [Vis alle 8 forfattere av denne artikkelen] (1998). Injection and expression of foreign DNA in single skeletal muscle fibers in vivo. Fulltekst i vitenarkiv
• Bruusgaard, Jo C. & Gundersen, Kristian (2005). Number and spatial distribution of myonuclei studied in vivo. Universitetet i Oslo. Fulltekst i vitenarkiv
• Bruusgaard, Jo C. (1999). Hemming av acetylcholinreseptorsyntese i enkelt-musklefibre in vivo. Universitetet i Oslo. Fulltekst i vitenarkiv

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