• BMB Reports
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• v.33 no.6
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• pp.531-536
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• 2000

Tropomyosin (TM) is an important actin binding protein involved in regulation of muscle contraction. Unacetylated striated tropomyosin failed to bind to actin whereas unacetylated smooth tropomyosin bound well to actin. It has been demonstrated that high actin affinity of unacetylated ${\alpha}-tropomyosin$ was ascribed to the carboxyl terminal amino acid residues. In order to define the role of the carboxyl terminal residues of tropomyosin molecule on actin binding, two mutant tropomyosins were constructed. TM11 is identical to the striated tropomyosin except that the carboxyl terminal last three amino acids was replaced with $^{282}NNM^{284}$ whereas in TM14 $^{276}HA^{277}$ was substituted with smooth specific $^{276}QT^{277}$. TM11 and TM14 were overproduced in Escherichia coli and analyzed for actin affinity. The apparent binding constants (Kapp) of unacetylated tropomyosins were $2.2{\times}10^6M^{-1}$ for sm9, $1.03{\times}10^6M^{-1}$ for TM14, $0.19{\times}10^6M^{-1}$ for TM11, $>0.1{\times}10^6M^{-1}$ for striated, respectively. This result indicated that higher actin affinity of the unacetylated smooth tropomyosin was primarily attributed to the presence of QT residues in the smooth sequence. In case of the Ala-Ser (AS) dipeptide extension of the amino terminus of tropomyosin, Kapp were $21.1{\times}10^6M^{-1}$ for AS-sm9, $8.0{\times}10^6M^{-1}$ for AS-11, $4.7{\times}10^6M^{-1}$ for AS-14, $3.8{\times}10^6M^{-1}$ for AS-striated. AS-TM11 showed considerably higher actin affinity than AS-TM14, implying that interaction of Ala-Ser of the amino terminus with the carboxyl terminal residues. Since Kapp of AS-TM11 was significantly lower than that of AS-sm9, the presence of QT might be required for restoration of high actin affinity of the smooth ${\alpha}-tropomyosin$. These results suggested that the carboxyl terminal amino acid residues Glutamine275-Threonine276 are important for actin affinity of the recombinant smooth ${\alpha}-tropomyosin$, particularly of unacetylated smooth ${\alpha}-tropomyosin$.

• Applied Microscopy
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• v.50
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• pp.20.1-20.9
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• 2020

Arthropods have an open circulatory system with a simple tubular heart, so it has been estimated that the contractile pumping structure of the cardiac muscle will be less efficient than that of vertebrates. Nevertheless, certain arthropods are known to have far superior properties and characteristics than vertebrates, so we investigated the fine structural features of intercalated discs and cardiac junctions of cardiac muscle cells in the black widow spider Latrodectus mactans. Characteristically, the spider cardiac muscle has typical striated features and represents a functional syncytium that supports multiple connections to adjacent cells by intercalated discs. Histologically, the boundary lamina of each sarcolemma connects to the basement membrane to form an elastic sheath, and the extracellular matrix allows the cells to be anchored to other tissues. Since the intercalated disc is also part of sarcolemma, it contains gap junctions for depolarization and desmosomes that keep the fibers together during cardiac muscle contraction. Furthermore, fascia adherens and macula adherens (desmosomes) were also identified as cell junctions in both sarcolemma and intercalated discs. To enable the coordinated heartbeat of the cardiac muscle, the muscle fibers have neuronal innervations by multiple axons from the motor ganglion.

• Korean Journal of Veterinary Research
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• v.23 no.1
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• pp.69-79
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• 1983

The present studs was undertaken to observe the histopathological changes on the cardiac and skeletal muscles, and liver of rabbits fed a commercial ration, either alone or with supplements of Zinc (3,000mg/kg. of diet, as sulfate), Copper (1,500mg/kg. of diet, as sulfate), Linoleic acid (3% of diet), Zinc with Linoleic acid and Copper with Linoleic acid. In the skeletal muscle, light microscopic changes observed were cloudy swelling, hyaline degeneration, atrophy, fragmentation and coagulative necrosis of muscle fibers, and proliferation of fibroblasts and infiltration of mononuclear cells. Especially, in rabbits fed with supplements of Zinc with Linoleic acid and Copper with Linoleic acid, calcification with muscle fibers progressing to necrosis were often observed. In the myocardium, loss of muscle fibers with necrosis and vacuolization, hyaline degeneration, hemorrhage and congestion were observed. In the liver, congestion and necrosis of hepatocytes, and centrilobular necrosis were observed. Differences of histological changes among the experimental groups was not marked.

• Applied Microscopy
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• v.33 no.4
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• pp.325-333
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• 2003

Fine structural characteristics of the heart tube and its cardiac muscle cells in spider, Araneus ventricosus are investigated by both of scanning and transmission electron microscopes. The heart tube of the spider is extended mid-dorsally along the anterior part of the abdomen, and is consisted of the thin outer layer of connective tissue (epicardium) and the thick muscle layer (myocardium). The myocardium in the spider has a typical fanlike spiral structure toward anterior part put across between the muscle fibers. Therefore, it did not give rise to the intima, and muscle cells are in direct contact to the hemolymph. The heart tube appeared to be three pairs of ostia and numerous hemocytes accumulated at the inner surface of the myocardial layer. Among several kinds of the hemocytes, the oenocytoids are the most predominant hemocytes accumulated along the myocardial folds which stretched toward heart lumen. The heart muscle cells are cross striated, branched, and multinucleated. They contain a lot of mitochondria, which provide for the continuous energy demands of the heart. Thread-like ganglion on the dorsal side of the heart tube gives off axons that innervate the heart muscle cells.

• Journal of Chest Surgery
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• v.25 no.4
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• pp.347-355
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• 1992

The precise mechanism of the Excitation-Contraction Coupling is still uncertain. But the concept that Ca2+ induced Ca2+ release [CICR] from the Ryanodine receptor in the sarcoplasmic reticulum [foot structure] may play a major role in E-C coupling has been widely accepted since 1970`s. It is believed that increased cytosolic Ca2+ followed by CICR is main contributor for E-C coupling of striated muscle. Resulting phenomena of ischemic /post-reperfusion myocyte is increased cytosolic Ca2+, even to the absence of Ca2+ in reperfusate. So intracellular inhibitor to CICR might prevent the ischemic and reperfusion damage of myocardial cells. The relatively purified foot protein, especially heavy sarcoplasmic reticulum rich, of the skeletal muscle was incorporated into the black lipid bilayer [Phosphatidyl ethanolamine: Phosphatidyl serine=l: 1]. Under the steady state of membrane potential [+20 mV], ionic current through Ryanodine receptor was measured with Cs+ as charge carrier. In the cis chamber [Cytoplasmic side], Mg2+ strongly inhibited CICR of Ryanodine receptor[Kd=6.2 nM]. In conclusion, naturally existing intracellular free Mg2+ can inhibit CICR from intracellular Ca2+ reservior [heavy SR]. So post-ischemic or post-reperfusing myocardium could be preserved using additional free Mg2+ in cardioplegic solution or reperfusate, otherwise the optimal concentration is undetermined.

• Biomedical Science Letters
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• v.10 no.1
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• pp.23-29
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• 2004

Nebulin is a (Mr 600∼900 kDa) large actin-binding protein specific to skeletal muscle and thought to act as a molecular template that regulates the length of thin filaments. Cardiac muscles of higher vertebrates have been shown earlier to lack nebulin. Recently, full-length nebulin mRNA transcripts have been detected in heart muscle, but at lower levels than in skeletal muscle. Nebulin expression also was detected in the kidney, eye, and otic canal, suggesting that nebulin isoforms may also be expressed in these organs. We have searched for nebulin isoforms in brain of human using PCR and Northern blot. Here, we provide evidence that nebulin mRNA transcripts are expressed in brain. Seven nebulin isoforms (B, C, D, E, F, G and H form) are obtained in human skeletal muscle and four isoforms (B, C, G and H form) in human brain cDNA library. We cloned the 1.3 kb of nebulin fragment from human adult brain library by PCR. The identity of the PCR product was confirmed by sequence analysis. The partial brain nebulin sequence was 99% identical to the skeletal muscle cDNA as determined by Blast alignment. It contains two simple-repeats HR1, HR2 and linker-repeats exon l35∼143 except exon 140. It was different from skeletal muscle B form, which contain HR1 and HR8. These data suggest that nebulin isoform diversity occurs even more extensively than previously known, likely contributing to the distinct thin filament architecture of different striated muscles.

• The Korean Journal of Cytopathology
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• v.16 no.1
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• pp.61-65
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• 2005

Fibromatosis colli is a benign fibrous tissue proliferation of sternocleidomastoid muscle, which is usually observed during the first month of life, often associated with congenital torticollis. It should be differentiated from other neck masses in infants because the usual initial treatment of fibromatosis celli is conservative management and invasive therapy should be avoided. Fine needle aspiration cytology provides an excellent minimally invasive diagnostic way for evaluation of infantile neck masses. We describe three cases of fibromatosis colli diagnosed by fine needle aspiration cytology. All of them were younger than one month and presented as a neck mass. Clinical impressions were malignant tumors in two cases and fibromatosis colli in one case. Fine needle aspiration cytology revealed benign and mature fibroblasts and atrophic striated muscle fibers. The cytologic diagnosis was fibromatosis colli or benign fibous lesion.

• Applied Microscopy
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• v.15 no.1
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• pp.71-85
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• 1985

The ultrastructure on the dorsal vessel of 5-day-old cabbage butterfly, Pieris rapae L., was carried out using the transmission and scanning electron microscope. The results are as follows. 1) The aorta. The aorta is simple tubular type and consists of the inner and outer membrane of the myocardium and thick myocardium is located between them. However the inner membrane with $0.26{\mu}m$ thickness and outer membrane with $0.08{\mu}m$ are composed of fibrous materials, the former is composed of low and high densed fibrous materials and the latter appears homogeneous layer. The myocardium consists of typical striated muscles. The sarcomere with $1.6{\mu}m$ length and in cross section, each thick filaments are surrounded by $7{\sim}8$ thin filaments. The intercalated disc is joining the end of the two muscle cells, desmosomes and septate junctions are appeared between the neighboring muscle cells. 2) The heart. The heart composing of myocardium enclosed by its inner and outer membrane as the aorta has a series of well formed segmental chamber. The arrangement of myofilaments, cell adhensions and membrane elements are observed as same as at the aorta. The inner membrane of the heart is deeply invaginated into the myocardium than the outer membrane and a lot of well developed mitochondria with rod shape are aggregated in the folds. The longitudinally and transversely oriented tubule system formed by invagnation of the sarcolemma into the muscle bundle is built up dyad with the sarcoplasmic reticulum as the aorta. The slit is formed by deeply invagination of the inner membrane of myocadium toward the muscle layer and then the inner and outer membrane of myocardium are fused. Therefore, the ostium is formed between the myocardium and situated at the lateral side of the myocardium.

• Journal of Sasang Constitutional Medicine
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• v.15 no.2
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• pp.117-123
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• 2003

Multiple myositis is a disorder of unknown etiology characterized by an inflammatory myopathy involving striated skeletal muscle The case is about a patient who is 74 years old man. Both of his shoulder girdles and pelvic girdles were suddenly paralyzed. We diagnosed a patient's illness as multiple myositis. Treatment was Herb-medication and rest. And in the case of this patient, power of both shoulder girdles and pelvic girdles with physiolocal condition improved remarkably.

• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.361-363
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• 2009

Rhabdoid tumor is an aggressive neoplasm of animals and human. It is similar with rhabdomyosarcoma histopathologically. But cellular origin of this neoplasm showed no striated muscle origin by immunohistological and ultrastructural studies. Castrated male Shit-tzu dog, 6 years old, had a mass in the left gluteal region near to the tail. The mass was examined histopathologically and immunohistologically. Histopathologically, the tumor was consisted of large polygonal cell with abundant eosinophilic cytoplasm. The nuclei in some cells were marked eccentrically located. Immunohistochemically, many neoplastic cells were positive for vimentin. These findings were similar to histopathological and immunohistological features of human rhabdoid tumor and few rhabdoid tumors in animals.