Biomedical subjects

I Nonaka

Publications and source records attributed to I Nonaka.

At least 217 records · Page 12Linked to original sources

PubMed1995

Sarcolemmal indentation in cardiomyopathy with mental retardation and vacuolar myopathy.

Muscle biopsies from three patients with cardiomyopathy, mental retardation and increased serum creatine kinase levels revealed scattered fibers with tiny intracytoplasmic vacuoles containing basophilic and acid phosphatase-positive material and slightly increased amounts of PAS-positive granules. These findings are consistent with those seen in the so-called lysosomal glycogen storage disease with normal acid maltase. In addition to the vacuoles, there were occasional folds or indentations in the sarcolemma which were connected to the membrane enclosing the vacuoles. These membranes were well demonstrated histochemically by the nonspecific esterase and acetylcholinesterase stains. On electron microscopy, most of the vacuoles were bounded by membranes with basal lamina. The vacuolar membrane stained positively with antibodies raised to dystrophin, dystrophin-associated glycoproteins, laminin and type 4 collagen, and it was identical to the sarcolemma and its basal lamina. Therefore, the membrane abnormality which causes sarcolemmal folding is probably critical to understanding the pathomechanism of this disease.

Adolescent↗

PubMed1995

A severe muscular dystrophy patient with an internally deleted very short (110 kD) dystrophin: presence of the binding site for dystrophin-associated glycoprotein (DAG) may not be enough for physiological function of dystrophin.

We report a 4-yr and 5-month-old boy with severe clinical features of an early-onset Duchenne muscular dystrophy, who had a very short (110 kDa) dystrophin at the sarcolemma. The patient had a large deletion (exons 2-44) of the dystrophin gene which was predicted to cause a reading frame shift. Sequence analysis of dystrophin mRNA in muscle revealed an alternatively spliced gene product from exons 1 to 51 that caused restoration of the reading frame, in addition to an mRNA corresponding to the DNA deletion. A consistent result was obtained by immunocytochemical analysis of muscle; i.e. positive staining for dystrophin at the sarcolemma using antibodies against the C-terminus, cysteine-rich region and last three of 24 repeat units of the central rod-domain, but not for the remaining antibodies for dystrophin that recognize the N-terminal and proximal rod-domains. Immunostaining for dystrophin-associated glycoproteins (DAGs: 43 and 50 K) and merosin were preserved. Utrophin staining was positive but fainter than other DMD muscles. These results suggest that an extremely short dystrophin lacking the entire actin-binding site in the N-terminus cannot function properly even if the protein possesses the putative DAG-binding cysteine-rich and the C-terminal domains, and still has an ability to associate with sarcolemmal membrane.

Base Sequence↗

PubMed1995

The 8,344 mutation in mitochondrial DNA: a comparison between the proportion of mutant DNA and clinico-pathologic findings.

Ten patients, two men and eight women with mitochondrial encephalomyopathy, had an A-G mutation at nucleotide pair 8,344 in the mitochondrial DNA, the most common genetic defect in myoclonus epilepsy with ragged-red fibers (MERRF). Eight patients had the clinical and pathologic characteristics of MERRF including myoclonus, seizures, cerebellar ataxia and myopathy with ragged-red fibers. Two patients had atypical symptoms such as early onset of fatal cardiac failure and late onset of rapid mental deterioration, respectively. The striking feature in our patients with the 8,344 mutation cardiac involvement and two developed progressive heart failure. In the typical MERRF patients, the proportion of mutant mitochondrial DNA in their skeletal muscles, quantified by a single strand conformation polymorphism analysis, was above 85%. However, there was no significant correlation between clinical severity, histopathological findings and the proportion of mutant mtDNA in muscle biopsy samples, suggesting that non-ragged-red fibers play an important role in the phenotype expression of the mutants.

Adolescent↗

PubMed1995

The frequency of patients with 50-kd dystrophin-associated glycoprotein (50DAG or adhalin) deficiency in a muscular dystrophy patient population in Japan: immunocytochemical analysis of 50DAG, 43DAG, dystrophin, and utrophin.

The 50-kd dystrophin-associated glycoprotein (50DAG or adhalin) in the skeletal muscle has been shown to be deficient in patients with severe childhood autosomal recessive muscular dystrophy prevalent in North Africa. To elucidate the frequency of patients having the 50DAG deficiency in a muscular dystrophy population in Japan, we immunocytochemically examined 50DAG, 43DAG, dystrophin, and utrophin. A total of 243 patients with muscular dystrophy, among 1,035 diagnostic muscle biopsies during the past 2.5 years, were analyzed. We identified five unrelated patients (three females and two males who have no family history) with 50DAG deficiency in the sarcolemma. Thus, 2.1% (5/243) of our muscular dystrophy patient population had 50DAG deficiency.

Adolescent↗

PubMed1995

Immunological and biochemical characterization of biglycan-like haemopoietic factor.

Immunological and biochemical characteristics of a 100,000 MW biglycan-like haemopoietic factor, purified from thymic myoid cells 871207B, were studied to distinguish them from macrophage colony-stimulating factor (M-CSF), which they resemble in activity and biochemical properties. Rabbit antibody raised against a synthetic peptide fragment (J-1) designed from amino acid sequences specific to the 100,000 MW factor responded to 871207B cells, the conditioned medium of 871207B, and capillary-like structures in the thymus, but not to M-CSF producer L-929 cells or the conditioned medium of L-929 cells. In contrast, M-CSF epitope was detected in L-929 cells and the conditioned medium cells but not in 871207B cells or the conditioned medium, even after enzymatic digestion of glycosaminoglycan chains. Treatment of the 100,000 MW factor with chondroitinase ABC and AC produced a 50,000 MW component. Digestion of this product with N-glycanase resulted in a 40,000 MW protein component. These results suggest that the 100,000 MW factor is a proteoglycan consisting of a core protein with an apparent molecular mass of 40,000 MW, a 50,000 MW chondroitin sulphate chain and 10,000 MW N-linked oligosaccharide chains. A small amount of a 40,000 MW monocytic cell growth activity was also found in the 871207B cell-conditioned medium. An enzymatically obtained 40,000 MW factor, the conditioned medium 40,000 MW factor, and the 100,000 MW factor were specifically eluated from an anti-J-1 IgG-immobilized affinity column with monocytic cell growth activity, suggesting that the biological activity resides in the 40,000 MW core protein. The 100,000 MW factor induced the proliferation and differentiation of monocytic lineage cells from a variety of sources, such as bone marrow cells, peritoneal exudated cells and brain microglia cells.

Amino Acid Sequence↗

PubMed1995

[Non-Fukuyama type merosin-positive congenital muscular dystrophy with delayed muscle fiber type differentiation: a case report].

A patient with non-Fukuyama type merosin-positive congenital muscular dystrophy (nonFCMD) who had severe muscle weakness leading to early death was reported. He was the first product of epileptic mother who had been placed on phenobarbital and phenytoin. The patient had severe respiratory failure and muscle weakness at the neonatal period, and died at 4 months of age. Multiple joint contractures were also noted at birth. Serum creatine kinase was within normal limits (123 IU/l). Electromyography showed a myogenic pattern. Brain computed tomographic (CT) scan and magnetic resonance imaging (MRI) were normal without white matter lucency or pachygyria. Muscle biopsy revealed dystrophic changes and type 2C fiber predominance. Dystrophin, dystrophin-associated glycoproteins and merosin were all positively demonstrated. Although patients with merosin-positive nonFCMD have relatively mild clinical course, our patient had severe muscle weakness with fatal outcome. Defect in muscle fiber maturation and differentiation, such as an increase of undifferentiated type 2C fibers, may be a major factor to influence muscle symptoms in non FCMD.

Humans↗

PubMed1995

Cloning and mapping of a very short (10-kb) EcoRI fragment associated with facioscapulohumeral muscular dystrophy (FSHD).

Facioscapulohumeral muscular dystrophy (FSHD) is a dominantly inherited muscular disorder and the gene for FSHD has been mapped to chromosome 4q35. Recently, the DNA rearrangements associated with the disease were found in the EcoRI fragment detected by the probes p13E-11 and pFR-1, and deletions of the 3.3-kb KpnI repeat units within the EcoRI fragment are thought to cause the disease. In this study, we cloned the FSHD-associated EcoRI fragments (the shortest fragments identified to date: 10 kb) from 2 severely affected patients (unrelated). Restriction enzyme maps of the genomic fragments in the 2 patients revealed that the 10 kb fragments were identical and contained only one 3.3-kb KpnI repeat unit. These results suggest that deletions of the 3.3-kb KpnI repeat units are likely to associate with FSHD, and that the 10 kb fragments may provide a means of understanding the molecular details involved at the site of the chromosomal rearrangements in FSHD.

Adolescent↗

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

Sarcoglycan complex is selectively lost in dystrophic hamster muscle.

We recently reported that the dystrophin-associated glycoprotein (DAG) complex is biochemically divided into two subcomplexes: one is the dystroglycan complex comprised of 156DAG and 43DAG and the other is the sarcoglycan complex comprised of 50DAG, A3b, and 35DAG. A3b is a novel dystrophin-associated glycoprotein with an approximate molecular mass of 43 kd but is distinct from 43DAG. In the present study, we examined the striated muscles of the dystrophic hamster with anti-A3b antibody in addition to anti-50DAG, anti-43DAG, anti-35DAG, anti-dystrophin, and anti-laminin antibodies by both immunohistochemistry and immunoblot analysis and found that 50DAG, A3b, and 35DAG are selectively lost. This selective defect of the sarcoglycan complex in dystrophic hamster muscles may give rise to dystrophic changes in striated muscles. Thus, the differentiation of the dystrophin-associated glycoprotein complex into the dystroglycan and sarcoglycan complexes is important not only from a biochemical standpoint but also in understanding the cause of muscular dystrophy in the hamster. Our findings further show that the dystrophic hamster may serve as an animal model for a human disease, severe childhood autosomal recessive muscular dystrophy, which has recently been shown to result from a selective defect in the sarcoglycan complex.

Animals↗

PubMed1995

[Mitochondrial encephalomyopathies: 3243 mutation as a central matter].

Molecular diagnosis for mitochondrial diseases offers a powerful means to clarify that mitochondrial DNA (mtDNA) defects have different characteristics from those of nuclear DNA. Regarding the relationship between genotype and phenotype, there is a dual heterogeneity. It means that one mutation, for example, a 3243 mutation, has several clinical phenotypes, including MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes), myopathy only, diabetes and/or deafness and even CPEO (chronic progressive external ophthalmoplegia). Conversely, one phenotype, for instance, MELAS has several genetypes; 3243, 3271, and 3291 mutations. The second unique event in mitochondrial DNA mutation is heterogenous distribution of mutant mtDNA in a mitochondrion or a cell that is called heteroplasmy. The extend of heteroplasmy seems different from tissue to tissue providing clues to explain the variability of tissue impairment and heterogenous clinical symptoms. The above evidence suggests that we should take care in selecting tissues to be tested. The third problem remained is on maternal inheritance. It makes the genetic counselling on mitochondrial diseases at clinics difficult and laborious. In conclusion, mtDNA analysis must be used as a last resort to get final diagnosis.

Animals↗

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

A new point mutation at nucleotide pair 3291 of the mitochondrial tRNA(Leu(UUR)) gene in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).

A new point mutation at nucleotide pair 3291 in the mitochondrial tRNA-Leu(UUR) gene was found in a Japanese MELAS patient. The nucleotides at the mutated site were evolutionarily invariant from humans through sea urchins. The mutant genomes were detected in a heteroplasmic fashion in muscle and blood cells of the proband by means of PCR-RFLP. Among 46 MELAS, 5 MERRF, 23 CPEO and 55 normal controls examined, this is the only patient with the mutation. This is the third mutation associated with MELAS in addition to nucleotides at 3243 and 3271. All three mutations occurred within the tRNA-Lue(UUR) region indicating that the tRNA alteration is responsible for the MELAS phenotype.

Animals↗

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

Diffuse leukodystrophy with a large-scale mitochondrial DNA deletion.

An 8-year-old girl with progressive ataxia and bulbar palsy showed diffuse white-matter lesions in the occipital to parietal lobes on magnetic resonance imaging. Since she had slightly elevated lactate in the cerebrospinal fluid, a muscle biopsy was done which revealed scattered ragged-red fibres and focal cytochrome c oxidase deficiency. Southern blot and polymerase-chain-reaction analyses revealed a large-scale mitochondrial DNA deletion, which was 6990 base-pairs in length with 6 base-pair (-TCATCG-) direct repeats at the junctions. Mitochondrial DNA mutation should be considered as one of the candidate causes for diffuse leukodystrophy in children.

Base Sequence↗

PubMed1994

Mitochondrial myopathy with progressive decrease in mitochondrial tRNA(Leu)(UUR) mutant genomes.

A female patient with mitochondrial myopathy had a mitochondrial DNA mutation at nucleotide pair 3243, commonly seen in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS), but unlike MELAS patients, she had no central nervous system symptoms. Muscle weakness, which was most severe when she was 7 years old, improved gradually with age. Comparison of two muscle biopsies obtained at an interval of 12.5 years (7 and 20 years of age, respectively), revealed that the number of ragged-red fibers was markedly decreased and histochemical cytochrome c oxidase activity increased in parallel with the decrease in population of mutant genomes.

Adult↗

PubMed1994

Single muscle fiber analysis of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).

We examined muscle sections from 3 patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), using single-fiber polymerase chain reaction, histochemistry, and in situ hybridization. Most type 1 ragged-red fibers showed positive cytochrome c oxidase activity at the subsarcolemmal region, while type 2 ragged-red fibers had little cytochrome c oxidase activity. However, there was no difference in the amount of total (mutant and wild-type) mitochondrial DNAs (mtDNAs) and the proportion of mutant mtDNA between type 1 and type 2 ragged-red fibers. These observations suggest that mitochondrial proliferation and nuclear factors affect muscle pathology, including cytochrome c oxidase activity, in MELAS. Total mtDNAs were greatly increased in ragged-red fibers (about 5-17 times over those in non-ragged-red fibers). The proportion of mutant mtDNA was significantly higher in ragged-red fibers (88.1 +/- 5.5%) than in non-ragged-red fibers (63.2 +/- 21.6%). Thus, the amount of wild-type mtDNA as well as mutant mtDNA was increased in ragged-red fibers in MELAS, failing to support the contention of a replicative advantage of mutant mtDNA. The proportion of mutant mtDNA was significantly higher in the strongly succinate dehydrogenase-reactive blood vessels (83.2 +/- 4.2%) than in non-succinate dehydrogenase-reactive blood vessels (38.8 +/- 16.2%). It seems likely that systemic vascular abnormalities involving cerebral vessels lead to the evolution of stroke-like episodes in MELAS.

Base Sequence↗

PubMed1994

Expression of utrophin (dystrophin-related protein) and dystrophin-associated glycoproteins in muscles from patients with Duchenne muscular dystrophy.

We examined whether the dystrophin-associated glycoprotein complex (GPC), which serves to fix dystrophin to cell membranes, is present at the sarcolemma in Duchenne muscular dystrophy (DMD) muscles using an immunohistochemical method. Antibodies against 50DAG (A2) and 43DAG (A3a), the components of GPC, were used for the detection of GPC. We found that, although the amount of GPC was reduced in DMD muscles where utrophin but not dystrophin was distinctly present, 43DAG (A3a) was fairly heavily and 50DAG (A2) was lightly but distinctly stained on the cell surfaces. It is likely that the capability of utrophin to preserve 50DAG (A2) is less than that of dystrophin, although utrophin has been reported to bind to GPC. We also found that 43DAG (A3a) but not 50DAG (A2) was detected in the peripheral nerves where utrophin was detected. Therefore, it is likely that 43DAG (A3a) is essential for the fixation of utrophin to cell membranes, as in the case of dystrophin. 50DAG (A2) may play other important roles in the pathogenesis of DMD.

Cytoskeletal Proteins↗

PubMed1994

Initiation of satellite cell replication in bupivacaine-induced myonecrosis.

To determine how and when the satellite cells are stimulated to replicate in muscle regeneration, the rat soleus muscle was examined chronologically after bupivacaine-induced myonecrosis. Bromodeoxyuridine and desmin-positive mononuclear cells, indicating the start of satellite cell replication, were seen 25 h after bupivacaine treatment when macrophages had already invaded the sarcoplasm of necrotic fiber. These findings suggest that muscle regeneration starts as early as the time at which macrophages begin to scavenge necrotic material. Proliferating myoblasts increased in number, reaching a maximum at 49 h after myonecrosis, and decreased in number 3 days after the myoblasts fused with each other form myotubes. The satellite cell proliferation after bupivacaine-induced myonecrosis began at almost the same time as in crush injury, and earlier than after muscle transplantation using whole intact or minced muscle fragments. The earlier beginning and more rapid regenerating process probably resulted from the preservation of intact satellite cells, blood vessels and peripheral nerves in the bupivacaine-induced myonecrosis.

Animals↗