Specific Metabolic Properties of Rat Oculorotatory Extraocular Muscles Can Be Linked to Their Low Force Requirements

Asmussen, G; Punkt, Karla; Bartsch, Bengt; Soukup, Tomáš

doi:10.1167/iovs.07-1577

Cited by 16 publications

(8 citation statements)

References 49 publications

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“…The EOM produce a variety of eye movements, which in part is reflected in the variety of myofiber properties, anatomical location, biochemical adaptations, and physiological properties of myofibers. 34,53,54 Sustained and lower velocity eye movements, such as smooth pursuit or fixation of a visual target, require slow and sustained contractions and a nonfatigable muscle. [55][56][57] Eye muscles have the fastest shortening velocities among mammalian skeletal muscles, 58 and they are required for quick eye movements, such as saccades.…”

Section: Discussionmentioning

confidence: 99%

Adaptation of Slow Myofibers: The Effect of Sustained BDNF Treatment of Extraocular Muscles in Infant Nonhuman Primates

Willoughby

Filippi

Walton³

et al. 2015

Invest. Ophthalmol. Vis. Sci.

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Section: Discussionmentioning

confidence: 99%

Adaptation of Slow Myofibers: The Effect of Sustained BDNF Treatment of Extraocular Muscles in Infant Nonhuman Primates

Willoughby

Filippi

Walton³

et al. 2015

Invest. Ophthalmol. Vis. Sci.

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“… 32 – 34 Interestingly, recent studies showed an increased number of activated satellite cells in muscles from subjects with strabismus compared to normal control EOMs. 35 , 36 The normal skeletal muscle fiber type distinctions do not apply to the EOM, 37 , 38 and aspects of mitochondrial and calcium biology, 39 , 40 as well as other aspects of metabolism, and physiology differ significantly when the EOMs are compared to limb and body skeletal muscles. Thus, despite a long history of surgical treatment for this type of eye misalignment in children, we still do not understand the molecular and cellular biological underpinnings of strabismus in general, and, more specifically, over-elevation in adduction.…”

mentioning

confidence: 99%

Morphological Differences in the Inferior Oblique Muscles from Subjects with Over-elevation in Adduction

Rudell

Felius

McLoon

2020

Invest. Ophthalmol. Vis. Sci.

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We examined inferior oblique muscles from subjects with over-elevation in adduction for characteristics that might shed light on the potential mechanisms for their abnormal eye position. METHODS. The inferior oblique muscles were obtained at the time of surgery in subjects diagnosed with either primary inferior oblique overaction or Apert syndrome. The muscles were frozen and processed for morphometric analysis of myofiber size, central nucleation, myosin heavy chain (MyHC) isoform expression, nerve density, and numbers of neuromuscular junctions per muscle section. RESULTS. The inferior oblique muscles from subjects with Apert Syndrome were smaller, and had a much more heterogeneous profile relative to myofiber cross-sectional area compared to controls. Increased central nucleation in the Apert syndrome muscles suggested ongoing myofiber regeneration or reinnervation over time. Complex changes were seen in the MyHC isoform patterns that would predict slower and more sustained contractions than in the control muscles. Nerve fiber densities were significantly increased compared to controls for the muscles with primary inferior oblique overaction and Apert syndrome that had no prior surgery. The muscles from Apert syndrome subjects as well as those with primary inferior oblique overaction with no prior surgery had significantly elevated numbers of neuromuscular junctions relative to the whole muscle area. CONCLUSIONS. The muscles from both sets of subjects were significantly different from control muscles in a number of properties examined. These data support the view that despite similar manifestations of eye misalignment, the potential mechanism behind the strabismus in these subjects is significantly different.

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“…Extraocular muscles are developmentally, histologically, ultrastructurally, immunologically, metabolically, and functionally different to other skeletal muscle groups [160]–[166]. They have a mixture of several different fibre types, including singly innervated fast-twitch fibres and multiply innervated slow-twitch fibres [160], [161], [165]. Their NMJs are different, with lower AChR densities and lower quantal ACh contents [165].…”

Section: Clinical Manifestationsmentioning

confidence: 99%

“…It is not surprising that they are involved differently in various pathological processes. They are preferentially affected in some diseases such as myasthenia and chronic progressive ophthalmoplegia, and selectively spared in Duchenne muscular dystrophy and amyotrophic lateral sclerosis [161], [163], [164]. There needs to be further study at the molecular level of the effect of different snake venom neurotoxins on development of respiratory muscle weakness.…”

Section: Clinical Manifestationsmentioning

confidence: 99%

Neurotoxicity in Snakebite—The Limits of Our Knowledge

2013

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Snakebite is classified by the WHO as a neglected tropical disease. Envenoming is a significant public health problem in tropical and subtropical regions. Neurotoxicity is a key feature of some envenomings, and there are many unanswered questions regarding this manifestation. Acute neuromuscular weakness with respiratory involvement is the most clinically important neurotoxic effect. Data is limited on the many other acute neurotoxic manifestations, and especially delayed neurotoxicity. Symptom evolution and recovery, patterns of weakness, respiratory involvement, and response to antivenom and acetyl cholinesterase inhibitors are variable, and seem to depend on the snake species, type of neurotoxicity, and geographical variations. Recent data have challenged the traditional concepts of neurotoxicity in snake envenoming, and highlight the rich diversity of snake neurotoxins. A uniform system of classification of the pattern of neuromuscular weakness and models for predicting type of toxicity and development of respiratory weakness are still lacking, and would greatly aid clinical decision making and future research. This review attempts to update the reader on the current state of knowledge regarding this important issue.

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Specific Metabolic Properties of Rat Oculorotatory Extraocular Muscles Can Be Linked to Their Low Force Requirements

Cited by 16 publications

References 49 publications

Adaptation of Slow Myofibers: The Effect of Sustained BDNF Treatment of Extraocular Muscles in Infant Nonhuman Primates

Adaptation of Slow Myofibers: The Effect of Sustained BDNF Treatment of Extraocular Muscles in Infant Nonhuman Primates

Morphological Differences in the Inferior Oblique Muscles from Subjects with Over-elevation in Adduction

Neurotoxicity in Snakebite—The Limits of Our Knowledge

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