| 1. |
- Harandi, Vahid M., 1985-
(författare)
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A Muscle Perspective on the Pathophysiology of Amyotrophic Lateral Sclerosis : Differences between extraocular and limb muscles
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Amyotrophic lateral sclerosis (ALS) is a late-onset progressive neurodegenerative disorder. ALS has been traditionally believed to be primarily a motor neuron disease. However, accumulating data indicate that loss of contact between the axons and the muscle fibres occurs early; long before the death of motor neurons and that muscle fibres may initiate motor neuron degeneration. Thus, the view of ALS is changing focus from motor neurons alone to also include the muscle fibres and the neuromuscular junctions (NMJs). While skeletal muscles are affected in ALS, oculomotor disturbances are not dominant features of this disease and extraocular muscles (EOMs) are far less affected than limb muscles. Why oculomotor neurons and EOMs are capable to be more resistant in the pathogenetic process of ALS is still unknown.The overall goal of this thesis is to explore the pathophysiology of ALS from a muscle perspective and in particular study the expression and distribution of key neurotrophic factors (NTFs) and Wnt proteins in EOMs and limb muscles from ALS donors and from SOD1G93A transgenic mice. Comparisons were made with age-matched controls to distinguish between changes related to ALS and to ageing.Results: Brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4) were present in EOMs and limb muscles at both mRNA and protein levels in control mice. The mRNA levels of BDNF, NT-3 and NT-4 were significantly lower in EOMs than in limb muscles of early and/or late control mice, indicating an intrinsic difference in NTFs expression between EOMs and limb muscles. qRT-PCR analysis showed significantly upregulated mRNA levels of NT-3 and GDNF in EOMs but significantly downregulated mRNA levels of NT-4 in limb muscles from SOD1G93A transgenic mice at early stage. The NTFs were detected immunohistochemically in NMJs, nerve axons and muscle fibres. The expression of BDNF, GDNF and NT-4 on NMJs of limb muscles, but not of EOMs, was significantly decreased in terminal stage ALS animals as compared to the limb muscles of the age-matched controls. In contrast, NTFs expression in intramuscular nerve axons did not present significant changes in either muscle group of early or late ALS mice. NTFs, especially BDNF and NT-4 were upregulated in some small-sized muscle fibres in limb muscles of late stage ALS mice. All the four Wnt isoforms, Wnt1, Wnt3a, Wnt5a and Wnt7a were detected in most axon profiles in all human EOMs with ALS, whereas significantly fewer axon profiles were positive in the human limb muscles except for Wnt5a. Similar differential patterns were found in myofibres, except for Wnt7a, where its expression was elevated within sarcolemma of limb muscle fibres. β-catenin, a marker of the canonical Wnt pathway was activated in a subset of myofibres in the EOMs and limb muscle in all ALS patients. In the SOD1G93A mouse, all four Wnt isoforms were significantly decreased in the NMJs at the terminal stage compared to age matched controls.Conclusions: There were clear differences in NTF and Wnt expression patterns between EOM and limb muscle, suggesting that they may play a role in the distinct susceptibility of these two muscle groups to ALS. In particular, the early upregulation of GDNF and NT-3 in the EOMs might play a role in the preservation of the EOMs in ALS. Further studies are needed to determine whether these proteins and the pathways they control may be have a future potential as protecting agents for other muscles.
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| 2. |
- Byström, Berit, 1964-
(författare)
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Laminins and alpha11 integrin in the human eye : importance in development and disease
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The extracellular matrix (ECM) offers a protective shelter for cells and provides signaling paths important for cell to cell communication. ECM consists of basement membranes (BM) and interstitial matrix. BMs provide mechanical support for parenchymal cells, influence cell proliferation, survival, migration and differentiation. They are also important for tissue integrity. Laminins (LM) are the major non-collagenous component of BMs. Cell-ECM interactions, mediated by receptors, are indispensable during embryonic development, wound healing, remodeling and homeostasis of tissues. The integrins are the major cell-adhesion receptors. The expression of alpha11 integrin chain in the cornea is of great interest, as it is part of the alpha11beta1 integrin receptor for collagen type I, the predominant component of the corneal stroma.The aims were to thoroughly characterize the ECM in the developing and adult human eye, with particular focus on the cornea, LM and alpha11 integrin chains, and to examine alpha11 integrin chain in an animal model of corneal wound healing and remodeling. Human fetal eyes, 9-20 weeks of gestation (wg), and adult human corneas with different diagnosis were treated for immunohistochemistry with specific antibodies against LM and alpha11 integrin chains. Normal and knockout (ko) mice were treated with laser surgery to create a deep wound in the corneal stroma. The wound healing process was followed at different time points. The cellular source of alpha11 integrin chain was studied in cell cultures.In the fetal eyes, the BM of the corneal epithelium, the Descemet’s membrane (DM) and the Bruch’s membrane each had their specific combinations of LM chains and time line of development, whereas the lens capsule and the internal limiting membrane showed constant LM chain patterns.The epithelial BMs of normal and diseased adult corneas contained similar LM chains. The normal morphology of the epithelial BM was altered in the different diseases, particularly when scarring was present. In the scarred keratoconus corneas there were excessive LM chains. The majority of keratoconus corneas also expressed extra LM chains in the DM.At 10-17 wg alpha11 integrin chain was present in the human corneal stroma, especially in the anterior portion, but it was scarce at 20 wg, in normal adult corneas and in Fuchs’ endothelial dystrophy. In contrast, it was increased in the anterior portion of the stroma in keratoconus corneas with scarring. Alpha11 integrin ko mice had a defective healing with subsequent thinner corneas. Alpha11 integrin expression correlated to the presence of alpha-smooth muscle actin in vivo as well as in vitro.The distinct spatial and temporal patterns of distribution for alpha11 integrin and each of the LM chains suggest that they play an important role in human ocular differentiation. The selectively affected LM composition and the novel expression of alpha11 integrin chain in scarred keratoconus corneas as well as the pathologic healing in ko mice, indicate that alpha11 integrin and LM chains also play an important role in the process of corneal healing, remodeling and scarring and might participate in the pathogenesis of corneal disease. This knowledge is of practical importance for future topical therapeutic agents capable of modulating the corneal wound healing processes.
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| 3. |
- Hadrévi, Jenny, 1977-
(författare)
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Applying proteomics and metabolomics for studying human skeletal muscle with a focus on chronic trapezius myalgia
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Work related musculoskeletal disorders are the dominating causes of reported ill-health in industrialized countries. These chronic pain conditions are one of the most costly public health problems in Europe and North America. When work related musculoskeletal disorders are considered to be of muscular origin and the trapezius muscle is affected, the common appellation is trapezius myalgia. Since little is known about the genesis or how it is maintained, it is of great importance to better understand the pathophysiology of trapezius myalgia; doing so will better enable recommendations for prevention, treatment and rehabilitation. Several hypotheses have been presented based on biochemical alterations in the muscle, suggesting increased signaling of inflammatory substances and altered metabolism. Previous research has not been able to present the comprehensive picture of the muscle in pain. Thus there is a demand for more comprehensive research regarding the biochemical milleu of the chronic trapezius muscle.Proteomic and metabolomic methods allow non-targeted simultaneous analyses of a large number of proteins and metabolites. The main emphasis in this thesis is on a proteomic method, two-dimensional differential gel electrophoresis (2D-DIGE). The method is validated to human skeletal muscle biopsy research with laboratory specific settings. In the baseline study, there were 14 metabolic, contractile, structural and regulatory proteins that differed significantly in abundance when trapezius and vastus lateralis muscles were compared. Using the validated 2D-DIGE method and the baseline study, a comparison between healthy and myalgic muscles was made. Biopsies from female cleaners with and without myalgia were compared to obtain results from women with the same type of work exposure. In the multivariate model, 28 identified unique proteins separated healthy and myalgic muscle and were grouped according to function: metabolic (n=10), contractile (n=9), regulatory (n=3), structural (n=4), and other (n=2). Finally, a second screening method, metabolomics, was introduced to analyze differences in metabolite content as a complement to and verification of the proteomic results. Gas chromatography-mass spectrometry (GC-MS) was performed on muscle interstitial fluid samples obtained with microdialysis, and differences in the abundance of extracellular metabolites were revealed. The 2D-DIGE method is a reliable method to analyze human skeletal muscle. The outcomes of the proteomic analyses were dependant on the statistical approach. Systematic differences in protein and metabolite content were detected using a multivariate approach. Univariate analyses were used to analyze individual proteins for their significance. The significant proteins in the baseline study were predominately related to muscle fiber type which correlated with the differences in fiber type content between trapezius and vastus lateralis. The proteomic and metabolomics studies where myalgic and healthy muscles were compared provide us with new clues and new aspects regarding the pathophysiology of the myalgic muscle.Technically advanced methods employed in the thesis enabled an explorative screening of proteins of relevance for the pathophysiology of the myalgic muscle. The results of these analyses may contribute to the formulation of future hypothesis that need to be further evaluated.
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| 4. |
- Kawasaki, Aki, 1963-
(författare)
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Selective wavelength pupillometry to evaluate outer and inner retinal photoreception
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- PurposeIntrinsically photosensitive retinal ganglion cells (ipRGCs) express a unique photopigment called melanopsin. Capable of direct phototransduction, the ipRGCs are also influenced by rods and cones via synaptic inputs. Thus, the photoinput that mediates the pupil light reflex derives from both outer (rods and cones) and inner (melanopsin-mediated) retinal photoreception. This thesis has aimed to develop a pupillometric test that provides quantitative information about the functional status of outer and inner retinal photoreception in healthy eyes and in eyes with retinal degeneration. In addition to regulating the pupil light reflex, the ipRGCs signal light information for the circadian rhythm, thus, these two non-visual physiologic responses to inner retinal photoreception were examined simultaneously.MethodsPupil responses to a long and short wavelength light over a range of intensities (under conditions of light, mesopic and dark adaptation) were recorded using a customized infrared computerized pupillometer. Results were compared for two groups: patients with retinitis pigmentosa and controls. The response function threshold intensity and a half-max intensity was determined from the rod-weighted and cone-weighted pupil responses and correlated to extent of visual loss. The pupil response to light offset was assessed as a measure of direct melanopsin activation. Lastly, pupil responses to red and blue light at equal photo flux were recorded hourly during a 24-hour period and correlated to salivary melatonin concentrations in healthy subjects.ResultsIn normal eyes, the blue light evoked greater pupil responses compared to equiluminant red light. With increasing intensity, pupil contraction became more sustained which was most apparent with the brightest blue light. In patients with retinitis pigmentosa, the pupil responses mediated predominantly by rod and cone activation were significantly reduced compared to controls, (p<0.001) and the relative decrease in their contribution resulted in a greater influence of melanopsin on the post-stimulus response. Even at endstage retinal degeneration, pupil responses that derived predominantly from residual cone activity were detectable. The threshold intensity of the rod-mediated, but not cone-mediated, pupil response was also significantly reduced (p=0.006) in patients and the half-maximal intensity of rods correlated with severity of visual loss (r2=0.7 and p=0.02). In healthy controls, the melanopsin-mediated pupil response demonstrated a circadian modulation whereas the cone-mediated pupil response did not.ConclusionEarly and progressive loss of rod function in mild-moderate stages of retinitis pigmentosa is detectable and quantifiable as a progressive loss of pupillary sensitivity to extremely dim blue lights obtained under conditions of dark adaptation. In advanced stages of retinal degeneration, chromatic pupillometry is more sensitive than standard electroretinography for detecting residual levels of rod and especially cone activity. In addition, selective wavelength pupillometry can assess non-visual light-dependent functions. The timing of the post-stimulus pupil response to blue light is in phase with melatonin secretion, suggesting a circadian regulation of this pupil parameter.
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| 5. |
- Tjust, Anton, 1988-
(författare)
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Extraocular Muscles in Amyotrophic Lateral Sclerosis
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease of motor neurons characterized by muscle paralysis and death within 3-5 years of onset. However, due to unknown mechanisms, the extraocular muscles (EOMs) remain remarkably unaffected. The EOMs are highly specialized muscles that differ from other muscles in many respects, including innervation and satellite cells (SCs). Understanding whether these factors play a role in the relative sparing of EOMs in ALS could provide useful clues on how to slow down the progression of ALS in other muscles.The EOMs and limb muscles from terminal ALS patients and age-matched controls as well as the commonly used SOD1G93A ALS mouse model were studied with immunofluorescence. Antibodies against neurofilament and synaptophysin were used to identify nerves and neuromuscular junctions (NMJs); against Pax7, NCAM, MyoD, myogenin, Ki-67, dystrophin and laminin, to identify SCs and their progeny in EOMs and limb muscles. The proportion and fiber size of myofibers containing myosin heavy chain (MyHC) slow tonic and MyHC slow twitch were also determined in human EOMs.The abundance of SCs differed extensively along the length of control human EOMs, being twice as abundant in the anterior portion. Pax7-positive cells were also detected in non-traditional SC positions. EOMs from terminal ALS patients showed similar numbers of resting and activated SCs as the controls. In limb muscles of ALS patients, the number of resting and activated SCs ranged from low (similar to normal aged, sedentary individuals) to high numbers, especially in muscles with long duration of disease and varied between the upper and lower limbs. The EOMs maintained a high degree of innervation compared to hindlimb muscles of symptomatic SOD1G93A mice. MyHC slow tonic fibers were less abundant in ALS patients than in controls. The change seemed more pronounced in bulbar onset patients, and in this group of subjects only, there was a strong association between decline in MyHC slow tonic fibers and age of death. Notably, the decline in MyHC slow tonic fibers was unrelated to disease duration.Our data suggested that SCs play a minor role in the progression of ALS in general and in the sparing of the EOMs in particular. The generally preserved innervation in the EOMs of G93A mice may reflect distinct intrinsic properties relevant for sparing of the oculomotor system. Even though the EOMs are relatively spared in ALS, MyHC slow tonic myofibers were selectively affected and this may reflect differences in innervation, as these fibers are multiply innervated.
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| 6. |
- Vicente, André, 1986-
(författare)
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Aniridia-related keratopathy : structural changes, signaling pathways and clinical aspects
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aniridia is a congenital autosomal dominant, bilateral, panocular condition, caused by haploinsufficiency of the Pax6 transcription factor. Aniridia-related keratopathy (ARK) significantly affects vision and quality of life in these patients. ARK is a chronic progressive keratopathy comprising limbal stem cell deficiency associated with impaired epithelial cell adhesion, corneal conjunctivalization, epithelial erosions and corneal vascular pannus that typically only appear after childhood.The aims were i) to evaluate the structural changes and ii) cell signaling pathways, including the Notch1, Sonic Hedgehog (SHH), mTOR and Wnt/beta-catenin cell signaling pathways in naïve and surgically treated corneas of aniridia cases with advanced ARK and comparing with normal human adult and fetal corneas and iii) to develop a corneal cell culture model of aniridia.Naïve ARK corneas removed at the time of the first transplantation and ARK corneal buttons removed after a failed keratolimbal allograft and failed centered and decentered transplantations were included. These were compared with normal human adult and fetal (10-11 and 20 weeks) corneas. Sections were studied with immunofluorescence using antibodies against extracellular matrix components in the stroma and in the epithelial basement membrane (collagen I and IV, collagen receptor a11 integrin and laminin a3 chain), markers of fibrosis, wound healing and vascularization (fibronectin, tenascin-C, vimentin, a-SMA and caveolin-1), cell division (Ki-67) and macrophages (CD68); antibodies against Pax6 and keratin 13; and antibodies against elements of the Notch1 (Notch1; Dlk1; Numb), Wnt/beta-catenin (Wnt5a; Wnt7a; beta- catenin), Sonic Hedgehog (Gli1; Hes1) and mTOR (mTOR1; rpS6) signaling pathways. An in vitro cell culture model of mutant PAX6 corneal cells, obtained with CRISPR was created to study the same signaling pathways with Western blot and RT-qPCR.All ARK corneas and transplanted corneal buttons presented similar histopathological changes with irregular epithelium and disruption or absence of epithelial basal membrane. There was a loss of the orderly pattern of collagen lamellae and absence of collagen I in all ARK corneas. Vascularization was revealed in the pannus of all ARK corneas and the changes observed in decentered and centered transplants were analogous. Furthermore, ARK corneas presented analogous signaling pathways changes in the subepithelial pannus and epithelium, with decreased detection of Notch1 signaling pathway and increased presence of the Notch1 inhibitors Numb and Dlk1. Increased detection of Wnt/beta-catenin (enhanced presence of Wnt5a, Wnt7a and beta-catenin), SHH (detection of GLI1 and HES1) and mTOR (identification of mTOR and rpS6) signaling pathways were found in the subepithelial pannus and epithelium of all ARK corneas, when compared to normal controls. In the mutant PAX6 corneal cells, the signaling pathway changes encountered were similar to those found in the ARK patients. The cell signaling pathway dissimilarities encountered in ARK corneas were similar to the pattern found in human fetal corneas with the exception of Notch1.The analogous pathological features of all ARK cases and the similarity in pathway alterations found in all ARK corneas irrespective of being naïve or previously submitted to distinct surgical procedures involving transplantation of limbal stem cells or not, and mutant PAX6 corneal cells, advocates an important role for host specific factors in the pathophysiology of ARK. Moreover, the similar pattern found between fetal human corneas and ARK corneas indicates a less differentiated host milieu in ARK. The present results provide the basis for further studies investigating the possibility of modulating these pathways in order to delay or avoid ARK.
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| 7. |
- Dennhag, Nils, 1989-
(författare)
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Genetic studies of zebrafish muscles : clues to protection in muscle disease
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Muscular dystrophies (MDs) are caused by dysregulation of over 40 proteins but commonly share features of muscle weakness, myofiber death and regeneration, loss of ambulation and premature death. A MD involves a broken link anywhere in the connection from extracellular matrix through the sarcolemma to the sarcomere. Thus, any protein which is a part of this link causes MD if misfolded, dysregulated or absent. In MD, the most common causes of death are cardiac or respiratory failure, when the muscles involved in these processes fail. Although MDs affect 1:3500-5000 births worldwide there are currently no cures available. Extraocular muscles (EOMs) are strikingly not affected by MDs, however, the mechanisms behind this native resistance remain elusive. We have recently shown that the EOMs cytoskeleton differs significantly from that of other muscles and hypothesized that investigation of their cytoskeleton in MD models would provide important clues. Furthermore, we hypothesized that application of the EOMs strategies to trunk muscle tissue would decrease the detrimental impact of MD overall.The zebrafish model system has recently increased vastly in popularity, and has quickly become a MD model. Due to its compatibility with the CRISPR/Cas9 method, genetic knockout studies can be utilized to generate novel mutant lines tailored to fit various aspects in studies of the zebrafish skeletal muscle. In this thesis I present nine new zebrafish lines which I used to study muscle biology processes, including muscle regeneration and the EOM cytoskeleton. Our results clearly demonstrate the need for understanding compensatory mechanisms in biology. Interestingly, pax3 and pax7 were shown to functionally compensate for each other both in appendicular muscle formation and in muscle regeneration, respectively, two processes where these individual genes have great impact in other organisms. This finding would also prove to be important in aiding our understanding of the EOM biology in adaptive strategies towards MDs. Furthermore, our results show that zebrafish EOMs are a good model to study cytoskeletal composition, as they share important features with human EOMs. Utilizing the CRISPR/Cas9 genome editing technique, I developed several knockout models of cytoskeletal proteins (desmin, obscurin, plectin) and studied their importance for the function of the EOMs. In studies of zebrafish EOMs lacking obscurin, we found that EOMs functionally adapt their myosin composition over time via upregulation of myh7, a cardiac specific myosin. Furthermore, an RNA-sequencing screen on a CRISPR/Cas9 induced desminopathy model (desma; desmb double mutant) identified several protective genes of interest. We show that a four and a half LIM-domain protein (Fhl2) is upregulated in EOMs in several muscular dystrophy models and that fhl2b protects EOMs from excessive myonuclei turnover and hypertrophy. Furthermore, its ectopic expression in trunk muscle can also protect an additional muscle dystrophy model (dmd) from acute early death, improve myofiber function and stabilize neuromuscular junctions. Importantly, this protein was also detected in both human and mouse EOMs, indicating a potentially conserved role in the EOMs across species.In summary, we identified several novel strategies of adaptation to disease progression in the EOMs. Together, these findings have contributed significantly to a better understanding of the EOMs and suggest new treatment strategies for MD that may have important future clinical applications.
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| 8. |
- Kjellgren, Daniel, 1963-
(författare)
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Human extraocular muscles : molecular diversity of a unique muscle allotype
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: The extraocular muscles (EOMs) are considered a separate class of skeletal muscle, allotype. Myosin is the major contractile protein in muscle. The myosin heavy chain (MyHC) isoforms are the best molecular markers of functional heterogeneity of muscle fibers. The relaxation rate, reflects the rate at which Ca2+ is transported back into the sarcoplasmic reticulum (SR) mostly by SR Ca2+ATPase (SERCA). Myosin binding protein C (MyBP-C), plays a physiological role in regulating contraction. The laminins (Ln) are the major non-collagenous components of the basement membrane (BM) surrounding muscle fibers and are important for muscle fiber integrity. Methods: Adult human EOMs were studied with SDS-PAGE, immunoblots and immunocytochemistry, the latter with antibodies against six MyHC, 2 SERCA, 2 MyBP-C and 8 laminin chain isoforms. The capillary density was also determined. Results: Most fibers contained a mixture of MyHC isoforms. Three major groups of fibers could be distinguished. Fast fibers that stained with anti-MyHCIIa, slow fibers that stained with anti-MyHCI and MyHCeompos/MyHCIIaneg-fibers that stained with neither of these antibodies but with anti-MyHCI+IIa+eom and anti-MyHCeom. A majority of the fibers contained both SERCA1 and 2 whereas 1% were unstained with both antibodies. Biochemically SERCA2 was more abundant than SERCA1. MyBP-Cfast was not present in the EOMs and MyBP-Cslow was only detected immunocytochemically. The extrasynaptical BM of the EOM muscle fibers contained Lna2, b1, b2, g1, a4 and a5 chains. The capillary density in the EOMs was very high (1050 +/-190 capillaries/mm2) and significantly (p<0.05) higher in the orbital than in the global layer. Conclusions: The co-existence of complex mixtures of several crucial protein isoforms provide the human EOMs with a unique molecular portfolio that a) allows a highly specific fine-tuning regime of contraction and relaxation, and b) imparts structural properties that are likely to contribute to protection against certain neuromuscular diseases.
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