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K Arahata

Publications and source records attributed to K Arahata.

At least 91 records · Page 5Linked to original sources
PubMed1995

Inflammatory response in facioscapulohumeral muscular dystrophy (FSHD): immunocytochemical and genetic analyses.

To investigate the nature of the inflammatory response in facioscapulohumeral muscular dystrophy (FSHD), we analyzed mononuclear cells in muscle sections obtained from 18 FSHD patients and 8 controls. Monoclonal antibodies reactive for T cells, T cell subsets, B cells, and NK cells were used for cell typing. Macrophages were identified by acid phosphatase reaction. The localization of perforin, granzyme A, MHC-I and -II, dystrophin, and alpha-actinin antigens was also examined. We found that all FSHD patients, both familiar and sporadic cases, had greater amounts of mononuclear cellular infiltrates in muscle than controls, in whose specimens only few extra vascular mononuclear cells were counted. Seventy-two percent (13 of 18) of the patients had more than 50 inflammatory mononuclear cells per 1000 muscle fibers, and 33% (6 of 18) patients had numerous inflammatory cells exceeding 600 per 1000 muscle fibers (1835 +/- 482 SE). Nonnecrotic fibers invaded by mononuclear cells with either T8+, perforin+, or granzyme A+ were not observed in FSHD, while a few degenerating fibers were superficially invaded by T cells and macrophages. Occasional T cells were observed moving through the blood vessel wall. The increased number of necrotic fibers was paralleled by an increased number of inflammatory cells (r = 0.783, P = 0.0001). Genetic analysis, using the probes p13E-11, pFR-1, D4S139, and D4S163, was done in 6 patients (3 familiar, 3 sporadic) who had numerous inflammatory infiltrates. These 6 patients had small (< 28 kb) EcoRI fragments associated with the disease, and the disease was linked to 4q35. These results suggest that, in chromosome 4-linked FSHD: (1) inflammatory changes in muscle are a common histological feature; (2) mononuclear cellular infiltrates may enhance muscle fiber damage; but (3) T-cell-mediated cytotoxicity directed against muscle fibers is unlikely. We speculate that the immune effector mechanism in FSHD is different from that in previously reported inflammatory myopathies and Duchenne muscular dystrophy.

Adolescent↗
PubMed1995

Characterization of a tandemly repeated 3.3-kb KpnI unit in the facioscapulohumeral muscular dystrophy (FSHD) gene region on chromosome 4q35.

A 3.3-kb KpnI repeat unit within the tandem repeat locus (D4Z4) and its upstream 2.5-kb HincII/KpnI fragment of the facioscapulohumeral muscular dystrophy (FSHD) gene region at 4q35-qter were sequenced and characterized. The 3.3-kb KpnI unit was 3303 bp in length and contained two homeodomain sequences, one LSau-like sequence, and several microsatellites. The GC content in the 3.3-kb unit was very high (73%), while it was only 35% in the nonrepeated region of the 2.5-kb fragment. We identified 99% homologous sequences (918 bp) in the 3' end of the 3.3- and 2.5-kb fragments. These findings suggested that the repeated sequences at the D4Z4 start from 918 bp upstream to the first KpnI site.

Base Sequence↗
PubMed1995

[Genetic analysis of facioscapulohumeral muscular dystrophy (FSHD)].

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant muscular disorder which is characterized by progressive weakness and atrophy of the facial, shoulder-girdle and upper arm muscles, and occasional subsequent pelvic-girdle and lower limb involvement. The gene responsible for FSHD has been localized to chromosome 4q35-qter, although a few 4q-unlinked families are known. To examine FSHD-associated DNA rearrangements in the Japanese population, we performed Southern blot analysis of the genomic DNA, using the p13E-11 and pFR-1 probes. Most of the Japanese FSHD patients (> 95%) had specific smaller (< 28 kb) EcoRI fragments which cosegregated with the disease. Restriction enzyme maps of the polymorphic EcoRI fragment detected by the probes have revealed that the disease occurs due to a deletion of the integral numbers of the 3.3kb KpnI tandemly repeated fragments (D4Z4) which contain homeobox-like sequences. Indeed, we cloned and characterized the FSHD-associated EcoRI fragments (the shortest fragment identified to date: 10kb) from two severely affected patients (unrelated). The 10kb fragment were identical and contained only one 3.3kb KpnI repeat unit. Although we still do not know whether truncation deletion of the D4Z4 region could produce FSHD directly or indirectly (position effect), we now beginning to understand FSHD. In the next step, FSHD gene products (mRNA and protein) responsible for the disease should be investigated.

Chromosomes, Human, Pair 4↗
PubMed1994

Selective defect of sarcoglycan complex in severe childhood autosomal recessive muscular dystrophy muscle.

Dystrophin-associated glycoprotein complex is classified into two subcomplexes: the dystroglycan complex (156DAG and 43DAG) and the sarcoglycan complex (50DAG, A3b, and 35DAG). Severe childhood autosomal recessive muscular dystrophy (SCARMD) was first reported to result from a deficiency of 50DAG. We examined muscles from five SCARMD patients and found that dystrophin and 43DAG were present in almost normal levels while 35DAG and the newly-identified protein A3b in addition to 50DAG were absent or greatly reduced. Therefore, SCARMD is the disease with a selective defect of the sarcoglycan complex.

Child↗
PubMed1994

Expression of a novel human myotonin protein kinase (MtPK) cDNA clone which encodes a protein with a thymopoietin-like domain in COS cells.

A full-length cDNA of human myotonin protein kinase (MtPK) was cloned and expressed in COS-1 cells. MtPK is recovered from the cytosolic fraction of the COS extract as a 70 kDa protein, which coincides with the size deduced from the predicted amino acid sequence. The sequence has a significant homology to thymopoietin, a peptide hormone of the thymus. Biochemical characteristics of MtPK expressed in COS-1 cells and its expression in rat tissues are investigated.

Amino Acid Sequence↗
PubMed1994

Decreased myotonin-protein kinase in the skeletal and cardiac muscles in myotonic dystrophy.

To investigate the role of myotonin-protein kinase (MT-PK) in the pathophysiology of myotonic dystrophy (DM), we developed specific antibodies against synthetic MT-PK peptides. The antibody identified a 53kDa protein in skeletal muscle and recognized decreases in the amount of the protein in both adult and congenital DM patients, compared with amounts in controls and in patients with other muscle diseases. In cardiac muscle, this antibody identified a 62kDa protein, and in brain, both the 53 and 62kDa proteins were detected. These results suggest the presence of tissue-specific isoforms of MT-PK.

Adult↗
PubMed1994

Elevated basic fibroblast growth factor in the serum of patients with Duchenne muscular dystrophy.

The mechanism whereby dystrophin deficiency leads to excessive fibrosis and muscle degeneration is not known. The absence of dystrophin in skeletal muscle is associated with reduced plasma membrane stability as evidenced by elevated serum levels of the cytoplasmic enzyme creatine kinase. Basic fibroblast growth factor, a cytoplasmic polypeptide growth regulator that stimulates connective tissue synthesis, induces satellite cell proliferation, and suppresses myogenic differentiation, is made by skeletal muscle. We hypothesize that dystrophin deficiency leads to the constant release of basic fibroblast growth factor, which in turn contributes to fibrosis and muscle weakness by stimulating connective tissue and suppressing skeletal muscle differentiation. As an initial step in testing this hypothesis, we measured basic fibroblast growth factor in the serum of Duchenne muscular dystrophy patients. We found that whereas basic fibroblast growth factor was undetectable in the serum of normal individuals (n = 200), levels were elevated in 11 of 18 patients with Duchenne muscular dystrophy.

Adolescent↗
PubMed1994

Abnormal dystrophin expression in patients with limb girdle syndromes.

Clinical differential diagnosis between Becker muscular dystrophy (BMD) and limb gridle muscular dystrophy (LGMD) may be difficult because the BMD clinical phenotype tends to overlap with other limb girdle syndromes, especially with LGMD. Therefore we studied the expression of dystrophin, the protein product of the Becker and Duchenne muscular dystrophy gene, in muscle biopsy specimens of 30 patients (18 males, of whom 15 represented spradic cases, and 12 females) diagnosed as having LGMD according to traditional clinical, electrophysiological and histological criteria. For dystrophin analysis, six different monoclonal antibodies directed against different epitopes of the dystrophin molecule were used. Immunocytochemically, five of the 30 LGMD patients (17%) showed abnormal dystrophin staining patterns diagnostic of BMD. Western blotting in these five patients, all sporadic cases, showed dystrophin of reduced size and/or abundance. Analysis of blood or muscle DNA using multiplex polymerase chain reaction revealed deletions in the dystrophin gene in three of the five. Thus, 5 of 15 (33%) sporadic male patients previously thought to have LGMD were identified as having BMD.

Adolescent↗
PubMed1994

Immunohistochemical analysis of perforin and granzyme A in inflammatory myopathies.

Perforin (PF) and granzyme A (GA) are candidates suspected of being cytolytic proteins of the granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. We analysed PF and GA in muscles from patients with inflammatory myopathies. Five cases of polymyositis (PM), two cases of inclusion body myositis (IBM), and five cases of dermatomyositis (DM) were studied immunohistochemically using anti-PF and GA antibodies raised against each synthetic peptide of human PF and mouse GA, together with a panel of monoclonal antibodies reactive for lymphocyte subsets. In PM and IBM, PF positive cells were colocalized with GA positive cells and occasionally invaded into the non-necrotic muscle fibres. The percentage of PF positive cells among the endomysial CD8 positive cell population was 9.9% (PM) and 12.5% (IBM), and the majority of the endomysial CD8 positive cells were alpha/beta T cells. In contrast, in DM, both PF and GA positive cells were very few in all cases. Only few inflammatory cells were CD16+ or CD57+ NK cells among these diseases. Our results suggest that PF and GA are secreted mainly from alpha/beta T cells, and may play a key role in muscle fibre damage in at least some PM and IBM, but not in DM.

Aged↗
PubMed1994

Immunostaining of dystrophin and utrophin in skeletal muscle of dystrophinopathies.

Immunostaining of biopsied skeletal muscle of 4 Duchenne (DMD), 12 Becker muscular dystrophy (BMD) and 3 DMD carriers' was performed using monoclonal antibodies against dystrophin and utrophin. In DMD, dystrophin-negative staining was observed except for revertant fibers which showed different stain patterns for each antibody. In 7 BMDs, there was faint/patchy stain in cases of deletion between exons 45-52, while in one case there was deletion between exons 12-17 and no stain was noted relevant to the deletion site. Moreover, in 2 cases of undetectable deletion, antibodies which recognize a terminal portion of the C-terminal domain revealed the absent stain. In DMD, the utrophin-positive fibers corresponded to dystrophin-negative fibers. In BMD, this relationship did not necessarily occur in each fiber. In DMD carriers, a cluster of dystrophin-negative fibers which was positive for utrophin were prominent. In dystrophinopathy, the immunostaining of dystrophin and utrophin is useful, in combination with dystrophin gene analysis to make a definite diagnosis.

Adolescent↗
PubMed1994

[CTG-repeat in myotonin protein kinase].

Myotonic dystrophy (DM) is one of the most common inherited neuromuscular diseases in adults with a global incidence of 1 in 20,000 individuals. DM is an autosomal dominant disorder characterized primarily by myotonia and progressive muscle weakness. DM has unique genetic feature of anticipation, that is, increasing disease severity from generation to generation. DM candidate gene encodes a protein kinase (myotonin protein kinase; MtPK) expressed ubiquitously, and nearly all cases of DM displayed expansion (about 100 to 1,000) of the CTG repeat in the 3'-untranslated region, whose repeating number is in proportion to the severity of the condition. The physiological functions, however, of MtPK and the triplet repeat expansion are not yet clear. Thus, to elucidate the molecular mechanism of DM and for therapy of DM at last, we started biochemical analysis of MtPK and molecular biological study of CTG repeat. First of all, we have cloned a full length cDNA for MtPK, which encodes 625 amino acid residues and contains 5 repeats of CTG. Detailed structural analysis of MtPK and expression study of MtPK using the cDNA were performed, and physiological function of MtPK is discussed based on the results.

Adult↗
PubMed1994

[Dystrophin-related protein in diaphragm, limb and myoblast transferred muscles of mdx mouse].

Expression of the dystrophin-related protein (DRP or Utrophin) was examined with Western blot and immunohistochemical methods in diaphragm, limb and also in myoblast transferred muscles of the mdx mouse. Although we have hypothesized that progressive fibrosis in the diaphragm of the mdx mouse has been due to a smaller amount of DRP expression compared with limb muscles, we could not find any difference in the amount of DRP or in the DRP localization pattern between the two muscle sites. In limb muscles treated with myoblast transfer, dystrophin-positive muscle fibers had no DRP on their surface membrane, although dystrophin-negative muscle fibers were DRP-positive. These findings suggest that excessive expression of DRP is suppressed in the normalized muscle fiber with dystrophin. It also appears that the histological differences seen in the different muscles of the mdx mouse are not due to the amount of DRP present.

Animals↗
PubMed1994

Detection of new paternal dystrophin gene mutations in isolated cases of dystrophinopathy in females.

Duchenne muscular dystrophy is one of the most common lethal monogenic disorders and is caused by dystrophin deficiency. The disease is transmitted as an X-linked recessive trait; however, recent biochemical and clinical studies have shown that many girls and women with a primary myopathy have an underlying dystrophinopathy, despite a negative family history for Duchenne dystrophy. These isolated female dystrophinopathy patients carried ambiguous diagnoses with presumed autosomal recessive inheritance (limb-girdle muscular dystrophy) prior to biochemical detection of dystrophin abnormalities in their muscle biopsy. It has been assumed that these female dystrophinopathy patients are heterozygous carriers who show preferential inactivation of the X chromosome harboring the normal dystrophin gene, although this has been shown for only a few X:autosome translocations and for two cases of discordant monozygotic twin female carriers. Here we study X-inactivation patterns of 13 female dystrophinopathy patients--10 isolated cases and 3 cases with a positive family history for Duchenne dystrophy in males. We show that all cases have skewed X-inactivation patterns in peripheral blood DNA. Of the nine isolated cases informative in our assay, eight showed inheritance of the dystrophin gene mutation from the paternal germ line. Only a single case showed maternal inheritance. The 10-fold higher incidence of paternal transmission of dystrophin gene mutations in these cases is at 30-fold variance with Bayesian predictions and gene mutation rates. Thus, our results suggest some mechanistic interaction between new dystrophin gene mutations, paternal inheritance, and skewed X inactivation. Our results provide both empirical risk data and a molecular diagnostic test method, which permit genetic counseling and prenatal diagnosis of this new category of patients.

Adolescent↗
PubMed1993

Muscle-specific calpain, p94, is degraded by autolysis immediately after translation, resulting in disappearance from muscle.

We previously identified a third type of the calpain large subunit named p94 as a cDNA whose mRNA is expressed exclusively in skeletal muscle at levels approximately 10-fold more abundant than those of the conventional calpain subunit. Rat skeletal muscle fractions were screened by two anti-peptide antibodies raised against two specific sequences in p94, but the p94 protein could not be found. To examine this apparent discrepancy between the amounts of mRNA and protein, wild-type p94 was expressed in COS cells. Although p94 mRNA was expressed normally in COS cells, only very small amounts of the protein and its presumed degradation products were detected by the antibodies described above. A series of COOH-terminal deletion mutants was constructed and expressed in COS cells and L8 cells, a rat myoblast cell line. When IS2, one of the specific regions of p94, was completely eliminated, the truncated p94 proteins were expressed normally, and the amount of the expressed proteins was at least 100-fold higher than with wild-type p94. Moreover, when site-directed mutagenesis was introduced to change the presumed active-site cysteine of p94 to serine or alanine, the mutated p94 proteins were highly expressed like the IS2-deleted mutants. These results indicate the following. 1) The mRNA for p94 is normally transcribed in COS, L8, and muscle cells; 2) the p94 protein becomes active in the cytosol immediately after translation; 3) the p94 protein virtually disappears from cells by autocatalytic degradation; and 4) the p94-specific IS2 region plays an important role in this degradation. In vitro translation experiments support this idea. Furthermore, p94 shows nuclear localization when expressed in COS cells. The physiological function of p94 in muscle is discussed on the basis of the analysis of these transfectants.

Amino Acid Sequence↗
PubMed1993

Immunoblot analysis of dystrophin-related protein (DRP).

Polyclonal antibodies against the carboxy-terminal portion of dystrophin-related protein (DRP), the putative autosomal gene product which shares sequence homology with dystrophin, show the clear expression of DRP in mouse fetal muscle and in cultured human muscle cells, but not in mature mouse or human muscle. DRP has the same molecular mass as X-linked dystrophin and is recovered from the membrane fraction, but is associated with membranes more loosely than dystrophin.

Amino Acid Sequence↗