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Biomedical subjects

I Nonaka

Publications and source records attributed to I Nonaka.

At least 145 records · Page 8Linked to original sources
PubMed1998

Myophosphorylase deficiency and limb-girdle muscular dystrophy in the same pedigree.

We report 2 familial patients with limb-girdle muscular dystrophy (LGD). The parents of patient 1 showed a consanguineous marriage and patient 2 was a paternal cousin of patient 1. Slowly progressive muscular weakness/wasting and dystrophic changes in the biopsied muscles were observed in both patients. However, a quantitative assay revealed a severely reduced myophosphorylase activity in patient 1 with normal activity in patient 2. A semi-ischemic exercise test disclosed no elevation of venous lactate in patient 1 with a normal increase in patient 2. A leukocytes DNA analysis in patient 1 did not show the gene deficits previously recognized in patients with McArdle's disease (McD). Patient 1 may only have abnormal myophosphorylase activity with dystrophic changes secondary to the myophosphorylase deficiency or coincidentally two genomic abnormalities for McD and LGD. LGD still has heterogenous etiologies and the responsible genes for these two disorders may be closely mapped.

Adult↗
PubMed1998

[Clinical and pathological studies on nemaline myopathy in adulthood].

We examined 22 biopsied muscles from adult patients who had the histopathological characteristics of nemaline myopathy. In the first group, 13 patients had muscle weakness and/or skeletal abnormalities, such as high-arched palate, pes cavus and scoliosis which are often accompanied with the congenital nemaline myopathy. Their appropriate diagnosis had never been made until muscle biopsy was done, because of benign clinical course. In the second group, the symptoms of nine patients became manifest in adulthood and failed to show typical skeletal abnormalities. However, six muscle biopsies showed the histopathologic characteristics of congenital nemaline myopathy; abnormal fiber type distribution including type 1 fiber predominancy, type 1 fiber atrophy and type 2B fiber deficiency. Three patients remained in good health until adulthood when they developed muscle weakness with pathologic findings of nemaline myopathy. Accordingly, nemaline myopathy in adulthood can be categorized into three forms; the first two forms have clinical and pathologic evidence of the congenital benign form, whereas the symptoms are too mild to be noticed. The third form is not a hereditary disorder which may result from autoimmune pathophysiology.

Adolescent↗
PubMed1998

[Pathophysiology in muscle fiber necrosis and regeneration with a particular reference to regenerating process].

It is well known that muscle fiber is capable of regeneration after myonecrosis even in a case of muscular dystrophies. We first examined how and when the regulatory genes for myogenesis, MyoD and myogenin were expressed in experimentally induced myonecrosis. MyoD, a responsible gene for myoblast proliferation began to express at 18 hours and reached to the maximum level 48 hours after necrosis. Myogenin known to play a role for myotube formation was most extensively expressed 72 hours after myonecrosis when the newly formed myotubes were recognizable, confirming that both genes were necessary for regenerating process. The MyoD and myogenin were also expressed in regenerating fibers in muscular dystrophies including dy mouse with progressive muscle weakness and mdx mouse with no apparent muscle symptom. The genes were more extensively expressed in mdx mouse, than dy mouse simply reflecting their respective regenerating activity.

Animals↗
PubMed1998

Animal models of muscular dystrophies.

Recent advances in molecular biology have indicated that many mutant animal models of muscular dystrophy share common genetic and protein abnormalities similar to those of the human disease. The best example is a model of Duchenne muscular dystrophy (DMD), the mdx mouse. Similar to dystrophic muscle in DMD patients, dystrophin protein is not expressed along the surface membrane, even though the mdx mouse has no apparent signs of muscular dysfunction. Because clinical and pathologic findings in the dystrophic (mxd) dog are similar to those in DMD patients, it also has been regarded as a good model for therapeutic trials. The best known and most extensively studied dy+dy+ mouse lacks merosin (laminin alpha2), which is one subunit of a basement membrane protein, laminin. Because approximately half of all patients with the classical form of congenital muscular dystrophy also lack merosin, availability of this animal has revived interest in the study of the pathologic mechanism of fiber necrosis resulting from this membrane defect. The dystrophic hamster is a model of limb-girdle muscular dystrophy with sarcoglycan deficiency in which one of the dystrophin-associated glycoproteins, delta-sarcoglycan, is defective. Because these animal models have common protein and genetic defects similar to those seen in people with muscular dystrophies, they have been widely used to examine the effectiveness of gene therapy and the administration of pharmacologic and trophic factors.

Animals↗
PubMed1998

[A case of congenital myopathy with the pathologic transformation from fiber type disproportion to type 1 fiber predominance myopathy].

Many patients with a severe infantile form of congenital myopathies have respiratory and feeding difficulties from early infancy. We experienced a male patient who required an artificial ventilation soon after birth and showed marked generalized muscle weakness involving the facial muscles. He had skull deformity and mild mental retardation at the age of one year and 10 months. The first muscle biopsy at the age of 1 month showed small caliber fibers and an increase in the number of undifferentiated type 2C fibers, indicating muscle fiber immaturity. Since type 1 fibers were smaller than type 2 fibers, he was tentatively diagnosed as having congenital fiber type disproportion myopathy. The muscle biopsied findings improved significantly in the second biopsy at 1 year of age which showed type 1 fiber predominance but no cytoarchitectural abnormalities. Accordingly, he was diagnosed as having congenital myopathy with type 1 fiber predominance. A severe neonatal form of congenital myopathies may show striking muscle fiber immaturity in the early infancy. This may later develop into characteristic morphologic findings such as the formation of nemalines and cores, and abnormal fiber type distribution.

Biopsy↗
PubMed1998

[The significance of Ulex europaeus agglutinin I lectin binding fibers in various muscular diseases].

In the present study, we have reported that Ulex europaeus agglutinin I (UEA I) lectin labeled muscle fibers in distal myopathy with rimmed vacuole formation (DMRV). UEA I binding to muscle fibers was also observed in a small number of biopsies with inflammatory myopathy, but not in other diseases, including neurogenic muscular atrophies and muscular dystrophies. In order to elucidate the relationship between this UEA I binding, rimmed vacuole formation and active autophagocytosis, we examined the UEA I binding fibers in other myopathies which frequently showed rimmed vacuoles, including adult onset acid maltase deficiency, oculo-pharyngo-distal type myopathy and oculopharyngeal muscular dystrophy. No UEA I lectin labeling fiber was observed in the diseases examined. We then studied UEA I binding behavior on 70 biopsies of inflammatory myopathy to characterize the clinical features of UEA I binding positive patients. UEA I binding fibers were observed in 3 of 28 patients (11%) with other collagen diseases, 11 of 36 (31%) without these disorders, and 2 of 6 (33%) with inclusion body myositis. There were no common clinical histories, complications or laboratory findings among the UEA I binding positive patients. In conclusion, a common process may exist between the muscle fiber degeneration in DMRV and subgroups of inflammatory myopathy patients, but the basic mechanism remains to be elucidated.

Adolescent↗
PubMed1998

[X-linked recessive myotubular myopathy with a splice-site mutation in the myotubularin gene].

We reported a male patient with X-linked myotubular myopathy in whom MTM 1 gene mutation was first identified in Japan. The patient had 9-nucleotide insertion between exons 11 and 12 due to aberrant splicing. The patient showed severe hypotonia and generalized muscle weakness at birth. Mechanical ventilation and tube feeding were necessary because of poor spontaneous respiration and sucking. On muscle biopsy, most of the muscle fibers were small and round, and had peripheral halos, showing immaturity. He had a moderate ventricular dilatation and mild brain atrophy on brain CT and MRI. However, whether these findings are causally related to the splice-site mutation remained obscure.

Child, Preschool↗
PubMed1997

Laminin alpha2 chain-null mutant mice by targeted disruption of the Lama2 gene: a new model of merosin (laminin 2)-deficient congenital muscular dystrophy.

Using the gene targeting technique, we have generated a new mouse model of congenital muscular dystrophy (CMD), a null mutant for the laminin alpha2 chain. These homozygous mice, designated dy3Kldy3K, are characterized by growth retardation and severe muscular dystrophic symptoms and die by 5 weeks of age. Light microscopy revealed that muscle fiber degeneration in these mice begins no later than postnatal day 9. In degenerating muscles, considerable amounts of TUNEL positive nuclei were detected as well as DNA laddering, suggesting increased apoptotic cell death was involved in the process of muscle fiber degeneration.

Animals↗
PubMed1997

Targeted disruption of exon 52 in the mouse dystrophin gene induced muscle degeneration similar to that observed in Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a degenerative disorder of the skeletal muscle in human and is caused by mutations in the dystrophin gene. The mdx mouse is a spontaneous mutant and an animal model for DMD. It has a point mutation in exon 23 of the dystrophin gene that eliminates the expression of dystrophin. However, this mutation does not disrupt the expression of four other shorter isoforms that are also expressed from the dystrophin gene through differential promoter usage. We generated another mutant mouse by gene targeting. Exon 52 of the dystrophin gene was disrupted, because the deletion of this exon is known to result in the DMD phenotype in human. In this mouse (mdx52), Dp140 and Dp260, shorter dystrophin isoforms, were absent in addition to dystrophin. The skeletal muscles were hypertrophic and the histology exhibited variations in the fiber size with a necrotic and regenerating process. This mouse is thus considered to represent another model for DMD.

Animals↗
PubMed1997

The interorganellar interaction between distinct human mitochondria with deletion mutant mtDNA from a patient with mitochondrial disease and with HeLa mtDNA.

For the examination of possible intermitochondrial interaction of human mitochondria from different cells, cybrids were constructed by introducing HeLa mitochondria into cells with respiration-deficient (rho-) mitochondria. Respiration deficiency was due to the predominance of mutant mtDNA with a 5,196-base pair deletion including five tRNA genes (DeltamtDNA5196). The HeLa mtDNA and DeltamtDNA5196 encoded chloramphenicol-resistant (CAPr) and chloramphenicol-sensitive (CAPs) 16 S rRNA, respectively. The first evidence for the interaction was that polypeptides exclusively encoded by DeltamtDNA5196 were translated on the introduction of HeLa mitochondria, suggesting supplementation of the missing tRNAs by rho- mitochondria from HeLa mitochondria. Second, the exchange of mitochondrial rRNAs was observed; even in the presence of CAP, CAPs DeltamtDNA5196-specific polypeptides as well as those encoded by CAPr HeLa mtDNA were translated in the cybrids. These phenomena can be explained assuming that the translation in rho- mitochondria was restored by tRNAs and CAPr 16 S rRNA supplied from HeLa mitochondria, unambiguously indicating interorganellar interaction. These observations introduce a new concept of the dynamics of the mitochondrial genetic system and help in understanding the relationship among mtDNA mutations and expression of human mitochondrial diseases and aging.

Chloramphenicol Resistance↗
PubMed1997

Myoclonus epilepsy associated with ragged-red fibers: a G-to-A mutation at nucleotide pair 8363 in mitochondrial tRNA(Lys) in two families.

In addition to well-known mutations at nucleotide pair 8344 and 8356 in mitochondrial DNA in patients with myoclonus epilepsy associated with ragged-red fibers (MERRF), we found a new G-to-A point mutation at nucleotide 8363 in two Japanese families. The probands had the typical clinical characteristics of MERRF. Since the 8363 mutation was present in a heteroplasmic state, and seen in none of 92 patients with other mitochondrial diseases or 50 normal individuals, this mutation is thought to be disease-related and probably specific to MERRF. As seen in muscle biopsies with the previous two mutations, focal cytochrome c oxidase (CCO) deficiency was the most characteristic finding. With single fiber analysis, the CCO-negative fibers contained a higher percentage of mutant DNA (88.4 +/- 6.6%) than CCO-positive fibers (65.1 +/- 8.0%). These findings suggest that mutations in tRNA(Lys) coding region are related to the MERRF phenotype and are responsible for the reduced CCO activity.

Adolescent↗
PubMed1997

Gene locus for autosomal recessive distal myopathy with rimmed vacuoles maps to chromosome 9.

Distal myopathy with rimmed vacuoles is an autosomal recessive muscular disorder, characterized clinically by weakness of the distal muscles in the lower limbs in early adulthood. Recently, the gene locus for familial vacuolar myopathy with autosomal recessive inheritance (hereditary inclusion body myopathy) was mapped to chromosome 9 by genome-wide linkage analysis of nine Persian-Jewish families. Since both disease conditions share similar clinical, genetic, and histopathological features, we analyzed seven families with distal myopathy with rimmed vacuoles using ten microsatellite markers within the region of the hereditary inclusion body myopathy locus. Significantly high cumulative pairwise lod scores were obtained with three markers: D9S248 (Z(max) = 5.90 at theta = 0), D9S43 (Z(max) = 5.25 at theta = 0), and D9S50 (Z(max) = 4.23 at theta = 0). Detection of obligate recombination events as well as multipoint linkage analysis revealed that the most likely location of the distal myopathy with rimmed vacuoles gene is in a 23.3-cM interval defined by D9S319 and D9S276 on chromosome 9. The results raise the possibility that distal myopathy with rimmed vacuoles and hereditary inclusion body myopathy in Persian Jews are allelic diseases.

Adult↗