| 1. |
- Kjellgren, Daniel, et al.
(författare)
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Laminin isoforms in human extraocular muscles
- 2004
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 45:12, s. 4233-4239
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To determine the laminin isoform composition of the basement membranes (BMs) in the human extraocular muscles (EOMs) and relate it to the fact that EOMs are spared in laminin alpha2-chain-deficient congenital muscular dystrophy. METHODS: Samples from adult human EOMs and limb muscle were processed for immunocytochemistry, with monoclonal antibodies against laminin chains (Ln) alpha1 to -5, beta1 and -2, and gamma1. Neuromuscular junctions (NMJs) were identified with acetylcholinesterase reaction. The capillary density was measured in sections stained with anti-Lnalpha5. RESULTS: The extrasynaptic BM of the EOM muscle fibers contained Lnalpha2, -beta1, -beta2, and -gamma1, and, in contrast to limb muscle, it also contained Lnalpha4 and -alpha5, to some extent. The distinct laminin composition of the EOMs was confirmed by the presence of Lutheran protein, an alpha5-chain-specific receptor not found in limb muscle. At the NMJs, there was increased expression of Lnalpha4 and expression of Lnalpha2, -alpha5, -beta1, -beta2, and -gamma1 was also maintained. The capillary density was very high (1050 +/- 190 capillaries/mm(2)) in the EOMs and significantly (P < 0.05) higher in the orbital (1170 +/- 180 capillaries/mm(2)) than in the global (930 +/- 110 capillaries/mm(2)) layer. CONCLUSIONS: The human EOMs showed important differences in laminin isoform composition and capillary density when compared with human limb muscle and muscles of other species. The presence of additional laminin isoforms other than laminin-2 in the BM of the extrasynaptic sarcolemma could partly explain the sparing of the EOMs in Lnalpha2-deficient congenital muscular dystrophy.
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| 2. |
- Kjellgren, Daniel, et al.
(författare)
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Myosin heavy chain isoforms in human extraocular muscle
- 2003
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology. - 0146-0404 .- 1552-5783. ; 44:4, s. 1419-1425
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the myosin heavy chain (MyHC) composition of human extraocular (EOM) and levator palpebrae (LP) muscle fibers. METHODS: Adult human EOMs and LP were studied with SDS-PAGE, immunoblots, and immunocytochemistry, with antibodies against six MyHC isoforms. Myofibrillar adenosine triphosphatase (mATPase) and reduced nicotinamide adenine dinucleotide (NADH)-TR activity and fiber area were also determined. RESULTS: Most of the fibers in both layers stained strongly with anti-MyHCIIa. Approximately 14% of the fibers in the global layer and 16% in the orbital layer were labeled with anti-MyHCI. The remaining 24% of the fibers in the global layer and 3% in the orbital layer were not stained with either of these two antibodies, but were reactive to anti-MyHCeom (MyHCeom(pos)/MyHCIIa(neg) fibers). The fibers stained with anti-MyHCI had acid-stable mATPase activity, and the remainder of the fibers had alkaline-stable mATPase activity. Almost all the slow fibers stained with both anti-MyHCI and anti-MyHCslow tonic in both layers. Anti-MyHCalpha-cardiac stained approximately 26% of these slow fibers in the orbital layer and 7% in the global layer. Some slow fibers in both layers lacked staining with anti-MyHCslow tonic or with anti-MyHCalpha-cardiac. MyHCemb and/or MyHCeom were also present in some of the fibers of all the groups. The LP did not stain with anti-MyHCslow tonic. CONCLUSIONS: The present study revealed that the human EOMs have a very complex fiber type and MyHC composition and differ significantly from the EOMs of other species. The features of the LP were distinct from those of the four recti, the obliquus superior, and the limb muscles.
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| 3. |
- Kjellgren, Daniel, et al.
(författare)
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Sarco(endo)plasmic reticulum ca2+ATPases (SERCA1 and 2) in human extraocular muscles
- 2003
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology. - 0146-0404 .- 1552-5783. ; 44:12, s. 5057-5062
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the composition of the fibers in human extraocular muscles (EOMs) with respect to the sarco(endo)plasmic reticulum Ca(2+)ATPases (SERCA)-1 and -2 and to investigate possible correlations between SERCA and myosin heavy chain (MyHC) composition. METHODS: EOM samples were processed for immunocytochemistry with monoclonal antibodies specific against SERCA1 (fast isoform), SERCA2 (slow isoform), or different MyHCs. A total of 1571 fibers were analyzed. Microsomal EOM fractions were analyzed with SDS-PAGE and immunoblots. RESULTS: The fast fibers, containing MyHCIIa, accounted for 79% of the fibers in the orbital layer (OL) and 74% in the global layer (GL). More than 99% of these fibers contained SERCA1, and 86% of them coexpressed SERCA1 and -2. Almost all slow fibers stained with SERCA2; 54% of those in the GL and all in the OL coexpressed SERCA1 and -2. Fifteen percent of the fibers in the GL and less than 1% in the OL were MyHCeom(pos)/MyHCIIa(neg) fibers. All these contained SERCA1 and in the OL also stained strongly with anti-SERCA2. Biochemically SERCA2 was more abundant than SERCA1. CONCLUSIONS: The human EOMs had a very complex pattern of expression of the major protein regulating fiber relaxation rate. The coexistence of SERCA1 and -2, together with complex mixtures of MyHCs in most of the fibers provide the human EOMs with a unique molecular portfolio that allows a highly specific fine-tuning regimen of contraction and relaxation.
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| 4. |
- Lindström, Mona, et al.
(författare)
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Satellite cell heterogeneity with respect to expression of MyoD, myogenin, Dlk1 and c-Met in human skeletal muscle : application to a cohort of power lifters and sedentary men
- 2010
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Ingår i: Histochemistry and Cell Biology. - : Springer Science and Business Media LLC. - 0948-6143 .- 1432-119X. ; 134:4, s. 371-385
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Tidskriftsartikel (refereegranskat)abstract
- Human satellite cells (SCs) are heterogeneous with respect to markers for their identification in the niche between the muscle fibre plasma membrane and its basal lamina. We have previously shown that, in biopsies from highly competitive power lifters, power lifters with long-term use of anabolic steroids and a population of healthy sedentary men, antibodies against the neuronal cell adhesion molecule (NCAM) and the paired box transcription factor Pax7 together label 94% of the SCs, NCAM alone labels 4% and Pax7 alone labels 1%. In the present study, we have further studied these biopsies with four markers related to SC activation and differentiation. Our study unequivocally shows that staining for MyoD and myogenin are present in nuclei of SCs and of myoblasts and myotubes in areas of muscle fibre regeneration. Staining for c-Met was observed in a proportion of Pax7+ SCs. However, widespread labelling of the sarcolemma precluded the quantification of c-Met+/Pax7+ SCs and the use of c-Met as a reliable SC marker. Pax7+ SCs labelled by anti-Delta like1 (Dlk1) were present in all samples but in variable proportions, whereas muscle progenitor cells related to repair were Dlk1⁻. Staining for Dlk1 was also observed in Pax7⁻ interstitial cells and in the cytoplasm of some small muscle fibres. Interestingly, the proportion of Dlk1+/Pax7+ SCs was significantly different between the groups of power lifters. Thus, our study confirms that human SCs show marked heterogeneity and this is discussed in terms of SC activation, myonuclei turnover, muscle fibre growth and muscle fibre damage and repair.
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| 5. |
- Liu, Jing-Xia, et al.
(författare)
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Distribution of SERCA isoforms in human intrafusal fibers
- 2003
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Ingår i: Histochemistry and Cell Biology. - : Springer. - 0948-6143 .- 1432-119X. ; 120:4, s. 299-306
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Tidskriftsartikel (refereegranskat)abstract
- The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) is a membrane protein that plays a crucial role in muscle relaxation by transporting cytosolic Ca2+ into the lumen of the sarco/endoplasmic reticulum. In this study, the presence of SERCA1 and SERCA2 was investigated in human intrafusal fibers by immunocytochemistry. Nuclear bag1 fibers contained both SERCA1 and SERCA2 isoforms, with predominant staining seen with SERCA2 in the A and B regions. Most nuclear bag2 fibers also contained SERCA1 and SERCA2 isoforms and their coexistence frequently occurred in the A region. SERCA1 was present whereas SERCA2 was generally absent in the nuclear chain fibers. The staining intensity seen with the SERCA1 monoclonal antibody varied in the order of chain>bag1>bag2. The expression of SERCA1 isoform was found to correlate with the presence of fast myosin heavy chain (MyHC) isoform in nuclear chain fibers, whereas for nuclear bag fibers there was no such apparent correlation between patterns of expression of SERCA and MyHC isoforms. The phenotype revealed for the human bag fibers was very sophisticated and adapted to attain a very wide range of contraction and relaxation velocities.
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| 6. |
- Liu, Jing-Xia, et al.
(författare)
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Fiber content and myosin heavy chain composition of muscle spindles in aged human biceps brachii
- 2005
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Ingår i: Journal of Histochemistry and Cytochemistry. - Baltimore : Williams & Wilkins Co.. - 0022-1554 .- 1551-5044. ; 53:4, s. 445-454
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigated potential age-related changes in human muscle spindles with respect to the intrafusal fiber-type content and myosin heavy chain (MyHC) composition in biceps brachii muscle. The total number of intrafusal fibers per spindle decreased significantly with aging, due to a significant reduction in the number of nuclear chain fibers. Nuclear chain fibers in old spindles were short and some showed novel expression of MyHC alpha-cardiac. The expression of MyHC alpha-cardiac in bag1 and bag2 fibers was greatly decreased in the A region. The expression of slow MyHC was increased in nuclear bag1 fibers and that of fetal MyHC decreased in bag2 fibers whereas the patterns of distribution of the remaining MyHC isoforms were generally not affected by aging. We conclude that aging appears to have an important impact on muscle spindle composition. These changes in muscle spindle phenotype may reflect an age-related deterioration in sensory and motor innervation and are likely to have an impact in motor control in the elderly.
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| 7. |
- Liu, Jing-Xia, et al.
(författare)
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Muscle spindles in the deep muscles of the human neck : a morphological and immunocytochemical study
- 2003
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Ingår i: Journal of Histochemistry and Cytochemistry. - : Sage Publications. - 0022-1554 .- 1551-5044. ; 51:2, s. 175-186
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Tidskriftsartikel (refereegranskat)abstract
- Muscle spindle density is extremely high in the deep muscles of the human neck. However, there is a paucity of information regarding the morphology and immunoreactivity of these muscle spindles. The objective of this study was to investigate the intrafusal fiber content and to assess the myosin heavy chain (MyHC) composition of muscle spindles from human deep neck muscles. In addition to the conventional spindles containing bag(1), bag(2), and chain fibers (b(1)b(2)c spindle), we observed a number of spindles lacking bag(1) (b(2)c spindle) or bag(2) (b(1)c spindle) fibers. Both bag(1) and bag(2) fibers contained slow tonic MyHCs along their entire fiber length and MyHCI, MyHCIIa, embryonic, and alpha-cardiac MyHC isoforms along a variable length of the fibers. Fetal MyHC was present in bag(2) fibers but not in bag(1) fibers. Nuclear chain fibers contained MyHCIIa, embryonic, and fetal isoforms with regional variations. We also compared the present data with our previous results obtained from muscle spindles in human biceps brachii and the first lumbrical muscles. The allotment of numbers of intrafusal fibers and the MyHC composition showed some muscle-related differences, suggesting functional specialization in the control of movement among different human muscles.
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| 8. |
- Liu, Jing-Xia, et al.
(författare)
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Myosin heavy chain composition of muscle spindles in human biceps brachii
- 2002
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Ingår i: Histochem Cell Biol. ; 50:2, s. 171-184
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Tidskriftsartikel (refereegranskat)abstract
- Data on the myosin heavy chain (MyHC) composition of human muscle spindles are scarce in spite of the well-known correlation between MyHC composition and functional properties of skeletal muscle fibers. The MyHC composition of intrafusal fibers from 36 spindles of human biceps brachii muscle was studied in detail by immunocytochemistry with a large battery of antibodies. The MyHC content of isolated muscle spindles was assessed with SDS-PAGE and immunoblots. Four major MyHC isoforms (MyHCI, IIa, embryonic, and intrafusal) were detected with SDS-PAGE. Immunocytochemistry revealed very complex staining patterns for each intrafusal fiber type. The bag(1) fibers contained slow tonic MyHC along their entire fiber length and MyHCI, alpha-cardiac, embryonic, and fetal isoforms along a variable part of their length. The bag(2) fibers contained MyHC slow tonic, I, alpha-cardiac, embryonic, and fetal isoforms with regional variations. Chain fibers contained MyHCIIa, embryonic, and fetal isoforms throughout the fiber, and MyHCIIx at least in the juxtaequatorial region. Virtually each muscle spindle had a different allotment of numbers of bag(1), bag(2) and chain fibers. Taken together, the complexity in intrafusal fiber content and MyHC composition observed indicate that each muscle spindle in the human biceps has a unique identity.
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| 9. |
- Pedrosa-Domellöf, Fatima, et al.
(författare)
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Human extraocular muscles : unique pattern of myosin heavy chain expression during myotube formation
- 2000
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology. - 0146-0404 .- 1552-5783. ; 41:7, s. 1608-1616
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To study the myosin heavy chain composition of the human extraocular muscles (EOMs) during development.METHODS: EOMs from human fetuses of 8 to 22 weeks of gestation were studied with immunocytochemistry and gel electrophoresis. Antibodies specific against nine isoforms of myosin heavy chain (MyHC) were used in serial frozen sections.RESULTS: The developing EOMs had a delayed time course of myotube formation and a unique composition and distribution of MyHCs compared with human limb skeletal muscle. The primary myotubes coexpressed two developmental isoforms of MyHCI from the earliest stages. The third developmental MyHCI delineated the future orbital layer at 10 to 12 weeks of gestation. MyHC-slow tonic also appeared early, whereas MyHC alpha-cardiac and MyHC-extraocular, important components of adult EOM, were never detected at the gestational ages studied.CONCLUSIONS: The developmental features of the EOMs differed significantly from those reported for limb muscles of the corresponding ages. It is clear that the knowledge of limb muscle development does not fully apply to more specialized muscles, such as the eye muscles. The extreme complexity displayed by the EOMs probably reflects their distinct embryonic origin, innervation, and regulatory program of myogenesis.
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| 10. |
- Soukup, T, et al.
(författare)
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Intrafusal fiber type composition of muscle spindles in the first human lumbrical muscle
- 2003
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Ingår i: Acta Neuropathologica. - : Springer-Verlag New York. - 0001-6322 .- 1432-0533. ; 105:1, s. 18-24
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Tidskriftsartikel (refereegranskat)abstract
- We studied muscle spindles in the first lumbrical muscle of adult humans using myofibrillar ATPase (mATPase) activity. We found that muscle spindles exhibited a marked variability with respect to the number, position, length and detailed histochemical features of nuclear bag1, nuclear bag2 and nuclear chain fibers. Regarding mATPase activity, the nuclear bag2 fibers displayed lower alkali-stable mATPase activity along their length and many nuclear bag1 fibers tended to have lower acid-stable activity in the outer B region, whereas nuclear chain fibers exhibited medium acid-stable mATPase activity at pH 4.6. Almost 10% of spindle fibers displayed atypical features, as they were either located only at one spindle pole or exhibited mixed characteristics at either pole. The number of intrafusal fibers per spindle varied between 8 and 24. Strikingly, only 2 pairs from 22 muscle spindles had identical allotments of their intrafusal fibers. Muscle spindles in the first human lumbrical muscle contained more intrafusal fibers (12.3 +/- 4 per spindle on average) and especially relatively more nuclear bag fibers compared to other human skeletal muscles. Since each spindle apparently represents a unique morphological and physiological entity, the observed variability in the number and characteristics of intrafusal fibers in the first human lumbrical muscle likely reflects a wide range of finely tuned muscle spindle responses.
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