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At least 1,621 records · Page 90Linked to original sources
PubMed1976

Autoantibodies to cardiac conducting tissue and their characterization by immunofluorescence.

(1) A new antibody has been found by immunofluorescence which reacts with cardiac conducting tissue using ox heart false tendons. It was detected in eight out of ninety-three cases of idiopathic heart block (8-6%), in one out of twenty-two cases of secondary heart block (4-5%) and in seven of 165 normal controls (4.2%), in titres varying from 1:10 to 1:40. Previous authors had indicated that this tissue might contain unique antigens. (2) Sera reacting with type I fibres in skeletal muscle (red zebra) were found to be of two varieties, one of which stained conducting fibres diffusely while it gave minimal staining of cardiac muscle; the other reacting with myofibrils in Purkinje cells and heart. (3) Some sera with high titre smooth muscle antibodies (SMA) reacted with conducting tissue together with skeletal and cardiac muscle, suggesting that the four tissues have at least one antigen in common. (4) Known non-organ specific antibodies behaved as expected on beef conducting fibres: striational fluorescence of myasthenia gravis sera reacted with the same patterns on Purkinje myofibrils; AMA and ANA produced IFL in expected locations; ribosomal antibodies reacted strongly, while LKM and reticulin antibodies showed no reactivity. (5) Although the incidence of specific Purkinje fibre antibodies was not significantly raised in idiopathic heart block, the clinical associations suggest that some cases might be related to autoimmunity possibly involving cell-mediated mechanisms as in polymyositis.

Adolescent↗
PubMed1994

[Clinical significance of immunohistochemistry and ultrastructural change of myocardium in viral myocarditis].

Endomyocardial biopsy (EMB) specimens from 56 patients with suspected viral myocarditis (VMT) were studied. With microscopical study of the EMB specimens stained with HE, 14 of the 56 cases were diagnosed as myocarditis (25%) and 24 as non-myocarditis (43%). But immunohistochemistry stain showed that the contents of myosin, actin and myoglobin reduced in 51 patients (91%). Ten of 56 specimens were observed under electron microscope (EM). EM examination revealed focal or diffuse lysis of myofibrils in 10 patients. The results showed that: (1) The myofibrils in VMT showed severe damage. (2) Immunohistochemistry and EM examination can be used as a supplement to the Dallas diagnosis standard in order to improve accuracy of EMB in diagnosing VMT.

Actins↗
PubMed1994

[Expression of myogenic differentiation program in cultured normal postmitotic mononucleated myoblasts and the aberrant differentiation in rhabdomyosarcoma cells].

Development of primary cultured chicken myogenic cells were studied using living cell micro-morphoanalysis, muscle specific protein immunofluorescent double staining, image projection analysis and 3H-TdR incorporation autoradiography methods. Changes in single, normal newborn myoblasts from the time of their last mitosis until 22 hr old were followed. All +/- 4 hr myoblasts were desmin+ and most were positive for alpha-actinin, zeugmatin, troponin-I (TnI), alpha-actin. titin, nebulin and myosin heavy chain (MHC). There was no obligatory temporal or spatial sequence in the order of the appearance of the major myofibrillar proteins. Nascent sister myoblasts assumed an exceptionally elongated bipolar morphology that is as singular to mononucleated postmitotic myoblasts as is their capacity to transcribe myofibrillar genes. The assembly of non-striated myofibrils (NSMFs) was evident in all 6-8 hr cells and was initiated in the absence of myomesin and C-protein. Myomesin first appeared along NSMFs in 10-14 hr old cells. C-protein was only found localized to transverse doublets bisecting 1.6 microns wide A-bands of assembled sarcomeres. Each newly assembled sarcomere presented the same invariant distribution of proteins that is found in adult sarcomeres. There is a lag of 16 or more hours between the first appearance of most of the major myofibrillar proteins and their assembly into NSMFs and the first appearance of striated myofibrils (SMFs). The observations indicated that the majority of normal myoblasts up-regulate the synthesis of myofibrillar proteins prior to, not after, fusion. In brief, new-born +/- 4 hr myoblasts expressed their differentiation program in the process as (1) withdrawal from the cell cycle: (2) initiation of synthesis and accumulation of desmin and 7 early myofibrillar proteins: (3) cellular elongation and assembly of NSMFs and SMFs: (4) acquisition of a fusion-competent sarcolemma. The expression of this cell autonomous myogenic differentiation program is distorted or blocked in rhabdomyosarcoma RD cells. The majority of RD cells expressed desmin (50-90%): among these desmin+ cells, 10-20% incorporated 3H-TdR. In addition, 60-78% of the mitotic cells were desmin+. Most desmin+ cells were myofibrillar protein negative. Only a small number of tumor cells (5-10%) expressed MHC, titin, alpha-actinin and s-alpha-actin. 3H-TdR positive nuclei were observed in these myofibrillar protein+ cells: 11-12% in titin+ or nebulin+ cells and 4% in MHC+ cells. But none of the mitotic cells were myofibrillar protein+.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Subcellular alterations of cardiac fibers in rats subjected to hypothyroidism.

Subcellular changes of the atrial cardiomyocytes of rats submitted to hypothyroidism caused by administration of 1 mg/100 g of body weight of propylthiouracil showed a) swollen mitochondria and lysis of their cristae; b) myofibrils with marked heterogeneity of patterns, some exhibiting rupture and loss of continuity of their myofilaments; c) lesser concentration of atrial granules in the perinuclear area; d) abundant granular interstitial tissue and collagen separating the myofibrils.

Animals↗
PubMed1993

Ultrastructural study of moniliformin induced lesions of myocardium in rats and mice.

Effects of moniliformin on the ultrastructure of the myocardium of mice and rats were studied. Mice were given moniliformin orally at a dose of 29.46 mg.kg-1 the LD50. One h after dosing, lesions of the mitochondria of the myocardial cells were found which became more severe in 2 and 3 h. Ultrastructural lesions were also observed in the myofibrils and sarcolemma. Rats were given moniliformin orally at the dosage of 6 mg.kg-1 once daily for 56 d. Lesions of mitochondria and myofibrils were relatively mild. In the myocardiac specimens taken from the 21d post-toxin administration, lesions of the sarcolemma became more obvious. These moniliformin-induced lesions were similar to the ultrastructural changes in the myocardium of patients with Keshan disease. Our findings indicate that there may be a close and important relationship between moniliformin intoxication and Keshan disease.

Animals↗
PubMed1977

Myogenesis and contraction in the early embryonic heart of the rainbow trout. An electron microscopic study.

Myogenesis in the embryonic heart of the rainbow trout, Salmo gairdneri (Rich.), was investigated electron microscopically from the 29th to the 41st somite stage. Thick and thin myofilaments are formed simultaneously as well as precursors of Z-lines, to which the thin filaments are attached. The genesis of filaments takes place in the region around the intracellular yolk droplets. The first myofibrils appear by the 33rd somite stage, probably formed by a mechanism of self-assembly in which the binding sites of actin and myosin participate. A- and I-bands do not develop before the 38th osmite stage. The contraction already begins during the 33rd somite stage in the middle of the tubular heart. Gradually, the peristaltic waves spread increasingly to other parts of the heart. In the 41st somite stage the entire heart is contractile and all myocytes contain myofibrils.

Animals↗
PubMed1995

The cardiac mutant gene c in axolotls: cellular, developmental, and molecular studies.

The cardiac mutant axolotl is an interesting model for studying heart development. The mutant gene results in a failure of heart cells to form organized myofibrils and as a consequence the heart fails to beat. Experiments have shown that mutant hearts can be "rescued" (i.e., turned into normally contracting organs) by the addition of RNA purified from conditioned media produced by normal embryonic anterior endoderm-mesoderm cultures. These corrected hearts form myofibrils of normal morphology. New advances in recombinant DNA technology applied to this system should provide significant insights into the regulatory mechanisms of myofibrillogenesis as well as the inductive processes related to the control of gene expression during embryonic heart development. In a broader biological sense, the use of gene c in axolotls is potentially capable of helping to solve major unanswered questions in modern biology related to the genetic regulation of differentiation in vertebrates.

Ambystoma↗
PubMedDate not supplied

[Solubilization of the AMP deaminase in the muscles of the teleost fish Scorpaena].

A considerable amount of AMP deaminase (AMPDA) in animal muscles is linked with myofibrils. This link is disturbed with growth of the ionic strength. A smooth increase of AMPDA solubilization has been showed in experiments with rabbit muscles when KCl concentration grew from 0 to 500 mM. Earlier we showed at trout muscles that an increase in KCl concentration from 0 to 200 mM in the homogenization medium induced growth of the bound enzyme portion followed by its decrease at the range of KCl concentrations 300-500 mM. Similar results were obtained in experiments with the sea scorpion muscles, which shows specific character of AMPDA interaction with myofibrils in teleost fish muscles. Comparison of the pH influence on AMPDA extraction from Scorpaena and rabbit muscles supported the idea on the specific character of this enzyme binding in the teleost muscles.

AMP Deaminase↗
PubMed1977

Ultrastructural alterations in skeletal muscle of ducklings fed selenium-vitamin E-deficient diet.

Newly-hatched ducklings were fed a selenium-vitamin E-deficient diet for 13 to 21 days. Ducklings were killed sequentially and the skeletal muscle alterations were studied by light and electron microscopy. An early alteration in skeletal muscle fibers was lysis of myofibrils, at first focal and later widespread. The sarcoplasm of damaged fibers appeared hyalinized by light microscopy. Degenerated skeletal muscle fibers with extensive lysis of myofibrils also had marked mitochondrial alterations, including swelling, formation of matrical densities, disruption of cristal membranes, and persistence of thick, dense, wavy, disrupted membranes. A sheath of external lamina persisted over degenerated segments of fibers which were invaded by macrophages that phagocytosed and removed the sarcoplasmic debris. Regeneration in damaged fibers was thought to proceed from thin subsarcolemmal satellite cells that survived the degenerative process. These satellite cells apparently developed into myoblasts, which fused to form myotubes that extended through the degenerated segments of fibers. Fibrillogenesis and sarcomerogenesis were apparent in myotubes. These structural alterations are discussed in terms of current knowledge of the combined biochemical role of selenium and vitamin E in maintaining cellular integrity.

Animals↗
PubMed1997

Localization of the Ca(2+)-binding S100A1 protein in slow and fast skeletal muscles of the rat.

The distribution of S100A1 in rat soleus and EDL muscles was studied immunocytochemically at the ultrastructural level using immunogold as marker. Antigens were localized mainly in myofibrils at all levels of the sarcomere. Immunogold particles along myofibrils were not uniformly distributed. The highest density of particles was found at Z-lines. An increase in particle density was observed in the middle of half A-bands in EDL and in the middle of half I-bands in the soleus. Antigen sites were also present at M-lines and at distinct locations of the sarcoplasmic reticulum.

Animals↗
PubMed1978

Isolation and characterization of flightless mutants in Drosophila melanogaster.

Since animal behaviour is executed through neuronal circuits including sensory receptors and muscle, genes vital for their development and differentiation must be found among mutants having behavioural anomaly. After mutagenesis with ethyl methanesulphonate (EMS), we screened for X-linked flightless mutants of Drosophila melanogaster by using column-type flight tester. Approximately 10(4) individuals were screened and 21 mutant genes were isolated. Chromosomal mapping and complementation experiments revealed that they belong to 15 cistrons randomly located on X chromosome, three cistrons having more than two alleles. Two of the isolated mutants (fltO2 and fltH, which are recessive both behaviourally and morphologically) were analysed with the mosaic fate mapping technique, and both were found to have their primary foci in mesodermal region of blastoderm, suggesting that the genes exert their primary effect in indirect flight muscle. Electronmicroscopic studies on the muscles from four alleles of the fltO2 cistron revealed an abnormality in myofibrillar arrangement. A possible deficit within Z-band components is discussed in relation to wings-up B mutants. The indirect flight muscle of flltH was also examined, and it was found that sarcomere length and diameter of myofibrils were abnormal. It was postulated that a possible factor which controls size of myofibrils is defective in this mutant. These examples indicate the advantage of combining ultrastructural examination with genetic mosaic mapping technique.

Animals↗
PubMed1998

Contribution of muscle proteinases to meat tenderization.

The exact mechanisms involved in the postmortem meat tenderization process and the nature of changes associated with improvement in tenderness are complex and not fully understood. Based on the relevant evidence thus far obtained, the focus of this review is on clarifying the factors affecting meat tenderness, particularly the toughening and tenderness phases, possible endogenous proteinases involved in meat tenderization and how these proteinases contribute to meat tenderization. Of the different biochemical and ultrastructural changes occurring in the meat tenderization process, myofibril disruption at the Z-disk and contractile proteins are discussed in detail. This myofibril disruption can perhaps be ascribed to the synergistic action of calcium-dependent proteinases (both mu- and m-calpains) and lysosomal proteinases, especially the cathepsins B and L.

Animals↗
PubMed1976

[Quantitative morphologic studies on hypoxically cultured rat myocardial cells].

Ventricle cells from neonatal rats were cultured in a medium preventing cell proliferation on a modified Roller apparatus with a defined pericellular oxygen partial pressure (pO2) of 38 or 0.6 mm Hg for about one week. The cells were harvested after the second and eighth day of culture (corresponding to one or seven days of culture under a defined pO2) and prepared for electron microscopy. Electron micrographs of this material were examined by stereologic techniques. The obtained results showed some deviations of mitochondrial fine structure of heart muscle cells depending on oxygen supply. During cultivation with a pO2 of 0.6 mm Hg (hypoxic conditions) we observed a proportional increase in mitochondria without cristae and an increase in size accompanied by a more irregular shape. On the contrary, the mitochondria of cells cultured with a pericellular pO2 of 28 mm Hg, which we consider to be a normoxic condition, did not show any deviation of inner membrane arrangement, but an increase in number and a decrease of size during cultivation was apparent. The mitochondria-myofibrils ratio decreased during cultivation in both conditions of oxygen supply. The ratio between sarcoplasmatic reticulum and myofibrils decreased markedly at a pO2 of 0.6 mm Hg.

Animals↗
PubMed1975

Structure of the muscles of the upper eyelid.

The human and monkey orbicularis muscle has fibers that are more uniform in size and structure than those of rectus muscles. They have distinct myofibrils, a moderate number of mitochondria, and a well-developed transverse T-tube system. The levator muscle also has relatively uniform fibers, but the myofibrils are less distinct than those of the orbicularis. Especially noteworthy is the unusual arrangement whereby Muller muscle arises directly from the undersurface of the levator muscle, causing an intimate intermingling of smooth and striated fibers. Muller muscle then inserts on the tarsus, whereas the levator muscle extends by an aponeurosis into the septa of the orbicularis muscle. In surgical specimens from patients with ptosis, the levator fibers show varying degrees of abnormality, whereas Muller fibers are normal.

Adolescent↗
PubMed1996

Multiple mitochondrial DNA deletions and persistent hyperthermia in a patient with Brachmann-de Lange phenotype.

In a newborn boy with characteristics of Brachmann-de Lange syndrome (BDLS) high temperatures were observed on the second day after birth and recurred 2-6 times daily during the 7 months of the patient's life. After transient hypertonia hypotonia developed. In muscle biopsy specimen taken on the 51st day of life, serious and progressive distortion of mitochondria was observed. In several mitochondria the cristae structure was broken, other mitochondria were shrunken and the damage progressed towards further deterioration in other organelles. At several points between the myofibrils amorphous material was seen possible debris of destroyed mitochondria. Most myofibrils seemed to be intact; however, in some areas myolytic signs were present. Analysis of the mitochondrial DNA (mtDNA) showed multiple deletions in skeletal and heart muscles, liver, lung and kidney. Since the mtDNA encodes several proteins of the respiratory complexes, the deleted mtDNA certainly affected the integrity of the mitochondrial oxidative phosphorylation process by synthesis of abnormal proteins. In the present case the hyperthermia may have been a result of the mtDNA damage.

Blotting, Southern↗
PubMed1999

Neuromusculature of the ovijector of ascaris suum (Ascaroidea, nematoda): an ultrastructural and immunocytochemical study.

This study used electron microscopy and confocal scanning laser microscopy interfaced with cytochemistry to study neuromuscular interrelationships in the ovijector of Ascaris suum. An extensive nerve plexus with both FaRPergic and non-FaRPergic components extends over the outer surface of the ovijector. The non-FaRPergic component is derived from nerve branches of the ventral nerve cord, whereas the FaRPergic component emanates from two large FMRFamide-immunoreactive neurons. In the vagina vera, most myofibrils are circular in orientation and a number of them divide and run for short distances in longitudinal and diagonal directions, their myofilaments are also orientated in a variety of directions. Parallel nerve fibres run in tracts along the length of the vagina vera with branches that penetrate the muscle layers. The vagina uteri possesses a thicker hypodermis than that of the vagina vera. It appears rich in secretory and phagocytic vesicles and the luminal side is invested with an electron-dense substance. The musculature of the vagina uteri is less well developed than that of the vagina vera, being restricted to circular myofibrils, with an apparent diagonal arrangement of myofilaments. Also, the innervation is less extensive in the vagina uteri with many fibres returning to the vagina vera to rejoin the nerve net and others continuing into the uteri.

Animals↗
PubMed1996

Partial characterization of zeugmatin indicates that it is part of the Z-band region of titin.

Zeugmatin is a muscle specific protein discovered by Maher et al. [1985: J. Cell Biol. 101:1871-1883] to be in Z-Bands of muscle and in the dense bodies of smooth muscle. Maher et al. [1985] generated a zeugmatin specific monoclonal antibody, McAb20, and then used immunoaffinity chromatography to isolate a 600-800 kD protein. During myofibrillogenesis of embryonic cardiac muscle, zeugmatin is detected in fully formed Z-bands in the mature myofibrils but not in the Z-bodies of premyofibrils [Rhee et al., 1994: Cell Motil. Cytoskeleton 28:1-24]. Rhee et al. [1994] have postulated that zeugmatin may be responsible for the fusion of the alpha-actinin containing Z-bodies to form the solid Z-Bands of the mature myofibrils. The current studies were undertaken to characterize the properties of zeugmatin. The McAb20 was used to probe a chicken heart lamba gt11 expression library, and three unique positive clones of 1.1, 1.4, and 1.7 kB were isolated. These were inserted into pcDNA3, sequenced, and assembled into a 1.8 kB ORF. A 60% identity with N-terminal region of the human cardiac titin sequence was revealed at the amino acid level. This region of the 1.8 kB zeugmatin sequence is located entirely in the Z-band region of the human cardiac titin molecule. The 1.1 kB clone of zeugmatin was subcloned into pTrcHisC and expressed in bacteria. Bacterial lysates were prepared and run over nickel columns to isolate a 46 kD fusion protein. This fusion protein formed a complex with purified alpha-actinin that could be immunoprecipitated with the zeugmatin specific antibody, McAb 20. The 1.1 kB sequence was transfected into non-muscle cell lines, PtK2 and REF. Twenty-four hours after transfection, the 46 kD zeugmatin peptide, not present in control non-muscle cells, was localized in focal adhesions and in a punctate pattern along the stress fibers. Double immunofluorescence staining revealed that zeugmatin colocalized with the alpha-actinin in the dense bodies and focal contacts of the stress fibers. At longer time points, as the transfected cells accumulated more truncated zeugmatin molecules, the cells lost adhesion plaques and stress fibers, and became detached from the substratum. Our results indicate the zeugmatin is part of the titin molecule that is located within the Z-band and that this section of the titin molecule anchors the actin crosslinking alpha-actinin molecules.

Actinin↗
PubMed1997

Complete cDNA sequence and tissue localization of N-RAP, a novel nebulin-related protein of striated muscle.

We have cloned and sequenced the full-length cDNA of N-RAP, a novel nebulin-related protein, from mouse skeletal muscle. The N-RAP message is specifically expressed in skeletal and cardiac muscle, but is not detected by Northern blot in non-muscle tissues. The full-length N-RAP cDNA contains an open reading frame of 3,525 base pairs which is predicted to encode a protein of 133 kDa. A 587 amino acid region near the C-terminus is 45% identical to the actin binding region of human nebulin, containing more than 2 complete 245 residue nebulin super repeats. The N-terminus contains the consensus sequence of a cysteine-rich LIM domain, which may function in mediating protein-protein interactions. These data suggest that the encoded protein may link actin filaments to some other proteins or structure. We expressed full-length N-RAP in Escherichia coli, as well as the nebulin-like super repeat region of N-RAP (N-RAP-SR) and the region between the LIM domain and N-RAP-SR (N-RAP-IB). An anti-N-RAP antibody raised against a 30 amino acid peptide corresponding to sequence from N-RAP-IB detected recombinant N-RAP and N-RAP-IB, but failed to detect N-RAP-SR. This antibody specifically identified a 185 kDa band as N-RAP on immunoblots of mouse skeletal and cardiac muscle proteins. In an assay of actin binding to electrophoresed and blotted proteins, we detected significant actin binding to expressed nebulin super repeats and N-RAP-SR, but only a trace amount of binding to N-RAP-IB. In immunofluorescence experiments, N-RAP was found to be localized at the myotendinous junction in mouse skeletal muscle and at the intercalated disc in cardiac muscle. Based on its domain organization, actin binding properties, and tissue localization, we propose that N-RAP plays a role in anchoring the terminal actin filaments in the myofibril to the membrane and may be important in transmitting tension from the myofibrils to the extracellular matrix.

Actins↗