Biomedical subjects

Itsuro Higuchi

Publications and source records attributed to Itsuro Higuchi.

30 records · Page 2Linked to original sources

PubMed2002

Miyoshi myopathy patients with novel 5' splicing donor site mutations showed different dysferlin immunostaining at the sarcolemma.

We analyzed five clinically defined cases of Miyoshi myopathy both genetically and immunologically. Western blot of muscle specimens confirmed that all of these patients had dysferlin deficiency. Immunohistochemistry revealed that two of the five patients showed positive dysferlin immunostaining. Subsequent mutation analysis of the dysferlin gene in these two patients revealed that both had novel 5' splicing donor site mutations. One patient with a homozygous G to C substitution at nucleotide 1036+1 exon 6 splicing donor site showed patchy sarcolemmal dysferlin immunostaining. The second patient with both a heterozygous G to A substitution at nucleotide 1310+1 exon 10 splicing donor site and a heterozygous C to G substitution at nucleotide 1939 (which induces Tyr 522 Stop of exon 18) showed both patchy sarcolemmal and diffuse cytoplasmic dysferlin immunostaining. In contrast to Becker muscular dystrophy, the clinical course and severity of dysferlin staining positive patients was not clearly different from negative patients. These results suggest that a splicing mutation of the dysferlin gene may have the potential to cause decreased dysferlin expression but may not be related to the milder clinical phenotype.

Adolescent↗

PubMed2002

Electron microscopic abnormalities of skeletal muscle in patients with collagen VI deficiency in Ullrich's disease.

By electron microscopy, we examined the skeletal muscle from two patients with Ullrich's disease. One patient had a deletion in the collagen VI alpha 2 gene. The muscle biopsy specimens showed no collagen VI immunoreaction, while the expression of collagen IV was increased. Collagen VI is a microfibrillar protein in the extracellular matrix with cell adhesive properties, and collagen IV is a principal component of the basal lamina. Electron microscopy revealed unevenness, extension, and folding of the muscle plasma membrane, and showed thickening and overproduction of the basal lamina. The data show that type VI collagen is certainly one of the important extracellular matrix components maintaining the structural integrity of skeletal muscle, and a defect of the collagen VI protein causes abnormalities of the muscle plasma membrane, dystrophic muscle changes, and up-regulation of collagen IV.

Adult↗

PubMed2002

Diagnosis of dystrophinopathy by skin biopsy.

We studied the expression of dystrophin in skin biopsy samples from 19 patients with neuromuscular diseases. Immunohistochemical procedures for dystrophin analyses were performed using monoclonal antibodies for three different domains. Arrector pili muscles, which are smooth muscles in the skin, expressed dystrophin in the patients with limb-girdle muscular dystrophy (5), facioscapulohumeral muscular dystrophy (1), and spinal muscular atrophy (3), and in normal controls (2). The C-terminus of dystrophin was slightly expressed in the patients with Duchenne muscular dystrophy, whereas the rod domain and N-terminus were absent. In one patient with Becker muscular dystrophy, the expression of dystrophin was reduced. The mosaic of dystrophin positive and negative smooth muscle fibers was observed in a manifesting carrier of Duchenne muscular dystrophy. Our results suggest that skin biopsy is very useful for the diagnosis of Duchenne/Becker muscular dystrophy and manifesting carrier of Duchenne muscular dystrophy, and can be performed even at an advanced stage of the disease.

Biopsy↗

PubMed2002

Fibronectin receptor reduction in skin and fibroblasts of patients with Ullrich's disease.

Ullrich's disease is a congenital muscular dystrophy characterized clinically by generalized muscle weakness, multiple contractures of the proximal joints, and hyperextensibility of the distal joints. Recent studies have demonstrated that collagen VI is deficient in the muscles of patients with Ullrich's disease, and some cases result from recessive mutations of the collagen VIalpha2 gene (COL6A2). Fibronectin is one of the main components of the extracellular matrix (ECM) and associates with a variety of other matrix molecules including collagen. The behavior of fibronectin on cells is mediated by fibronectin receptors, members of the integrin family. We studied the expression of fibronectin receptors and fibronectin in patients with Ullrich's disease, and found a marked reduction of fibronectin receptors in the ECM of skin and cultured fibroblasts of these patients. These results suggest that collagen VI deficiency may lead to the reduction of fibronectin receptors and that an abnormality of cell adhesion may be involved in the pathogenesis of Ullrich's disease.

Cells, Cultured↗

PubMed2002

Deficiency of a 180-kDa extracellular matrix protein in Fukuyama type congenital muscular dystrophy skeletal muscle.

Abnormalities of the proteins constituting the extracellular matrix have been shown to play important roles in the molecular pathogenesis of muscular dystrophies. In the present study, we have established a monoclonal antibody against a human skeletal muscle extracellular matrix protein. The antibody M1 recognized a single 180-kDa protein (p180) by immunoblot analysis of normal human skeletal muscle and gave a strong and continuous signal along the sarcolemma by immunohistochemical analysis. Furthermore, p180 could be solubilized either under a strong alkaline condition, or in the presence of EDTA or detergents such as Triton X-100, indicating that p180 was an extracellular matrix protein. Interestingly, p180 was deficient in the skeletal muscle of the patients with Fukuyama-type congenital muscular dystrophy (FCMD), but not other muscular diseases, by both immunohistochemical and immunoblot analyses. We presume that the deficiency of p180 in FCMD is caused specifically by the primary deficiency of fukutin, the causative protein of FCMD, and plays an important role in muscle cell degeneration in this disease.

Animals↗

PubMed2002

Targeted deletion of both thymidine phosphorylase and uridine phosphorylase and consequent disorders in mice.

Thymidine phosphorylase (TP) regulates intracellular and plasma thymidine levels. TP deficiency is hypothesized to (i) increase levels of thymidine in plasma, (ii) lead to mitochondrial DNA alterations, and (iii) cause mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). In order to elucidate the physiological roles of TP, we generated mice deficient in the TP gene. Although TP activity in the liver was inhibited in these mice, it was fully maintained in the small intestine. Murine uridine phosphorylase (UP), unlike human UP, cleaves thymidine, as well as uridine. We therefore generated TP-UP double-knockout (TP(-/-) UP(-/-)) mice. TP activities were inhibited in TP(-/-) UP(-/-) mice, and the level of thymidine in the plasma of TP(-/-) UP(-/-) mice was higher than for TP(-/-) mice. Unexpectedly, we could not observe alterations of mitochondrial DNA or pathological changes in the muscles of the TP(-/-) UP(-/-) mice, even when these mice were fed thymidine for 7 months. However, we did find hyperintense lesions on magnetic resonance T(2) maps in the brain and axonal edema by electron microscopic study of the brain in TP(-/-) UP(-/-) mice. These findings suggested that the inhibition of TP activity caused the elevation of pyrimidine levels in plasma and consequent axonal swelling in the brains of mice. Since lesions in the brain do not appear to be due to mitochondrial alterations and pathological changes in the muscle were not found, this model will provide further insights into the causes of MNGIE.

Animals↗

PubMed2002

Expression of midkine in regenerating skeletal muscle fibers and cultured myoblasts of human skeletal muscle.

Midkine is a member of a family of developmentally regulated neurotrophic and heparin-binding growth factors. The expression of midkine was examined immunohistochemically in biopsied muscle specimens from patients with various myopathies. The intense immunoreactivity of midkine was observed in the sarcoplasm at an early stage regenerating fibers of small diameter. Midkine immunoreactivity was also detected in cultured human skeletal muscle myoblasts from the proliferation stage to the differentiation stage. These results suggest that midkine may be an important skeletal muscle growth-promoting factor that participates in the growth process during skeletal muscle development, proliferation, and differentiation, and in the skeletal muscle regeneration in various neuromuscular disorders. This is the first report demonstrating the presence of midkine in skeletal muscle cells.

Biopsy↗

PubMed2002

Adult T-cell leukemia (ATL) cells which express neural cell adhesion molecule (NCAM) and infiltrate into the central nervous system.

We encountered a patient with adult T-cell leukemia/lymphoma (ATL) which expressed neural cell adhesion molecule (NCAM). The tumor cells markedly infiltrated the central nervous system (CNS) during the course of the ATL. The patient died 20 months after disease onset, which was considered to be early in the course. During the invasion of the CNS, the surface phenotype of the peripheral blood ATL cells by flow cytometric analysis was CD2+, CD3+, CD4+, CD7-, CD8-, CD16-, NCAM (CD56)+, HLA-DR-. We speculate that the infiltration of ATL cells into the CNS was closely related to the expression of the NCAM in this patient.

Blotting, Southern↗

PubMed2002