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Biomedical subjects

I Higuchi

Publications and source records attributed to I Higuchi.

At least 127 records · Page 7Linked to original sources
PubMed1993

Experimental germanium dioxide-induced neuropathy in rats.

We report an experimental model of germanium dioxide (GeO2)-induced neuropathy in rats. More than 6 months administration of GeO2 to young rats produced neuropathy characterized by segmental demyelination/remyelination and nerve edema. Electron microscopic studies demonstrated that changes in Schwann cells, such as an increased cytoplasmic volume or disintegration of the cytoplasm, were the earliest pathological findings. Schwann cell mitochondria contained high electron-dense materials. Subsequent removal of necrotic Schwann cell debris and myelin by invading macrophages was evident. These findings suggested that the Schwann cells themselves are the primary target of the toxin. The deposition of electron-dense granules in the intra-axonal vesicles, which was suggestive of glycogen granules in mitochondria, was observed in the advanced stage of the neuropathy. The findings of endoneurial edema with splitting of myelin lamellae were noted at the early stage of demyelination. Nerve edema may be the result of GeO2-induced endothelial cell injury.

Animals↗
PubMed1993

Chronic demyelinating neuropathy and intra-axonal polyglucosan bodies.

In this study we evaluated the relationship between polyglucosan bodies and peripheral nerve lesions. The biopsied sural nerve from a patient with late-onset chronic sensori-motor neuropathy showed many intra-axonal polyglucosan bodies and segmental demyelination/remyelination. The formation of Schwann cell hyperplasia around the demyelinated axons was found at the sites of polyglucosan bodies. These findings suggest that demyelinating neuropathy is a part of the spectrum of the diseases characterized by the accumulation of polyglucosan bodies within cellular compartments.

Aged↗
PubMed1993

Steroid-responsive myalgia in a patient with Becker muscular dystrophy.

We report a male patient with exercise-induced focal myalgia in the leg muscles. Dystrophin immunostaining of a biopsied muscle specimen from the patient showed the absence of or only faint immunoreactivity in 20% of the muscle fibers. The patient was diagnosed as having Becker muscular dystrophy. The myalgia was intractable and did not respond to non-steroidal anti-inflammatory drugs. The patient was placed on prednisone and found to be sensitive to it. Although he had recurrences of the symptom during tapering of the steroid, slower tapering over one year was tolerated. Steroid treatment may be useful for other Becker muscular dystrophy patients with myalgia.

Adult↗
PubMed1993

Molecular cloning of the guinea-pig histamine H1 receptor gene.

The histamine H1 receptor gene was isolated from a guinea-pig gene library. The gene contains no introns and encodes a protein of 488 amino acid residues. The structure of the guinea-pig histamine H1 receptor is predicted to contain seven putative transmembrane regions, which are similar to those of receptors coupling with GTP binding proteins. Although the third intracellular domain, the predicted binding site for the GTP binding protein, showed only 50% identity with those of the bovine and rat H1 receptors, the expressed guinea-pig H1 receptor was fully able to bind with [3H]mepyramine. Northern blot analysis indicated that the cerebrum, cerebellum, lung, adrenal, intestine, and heart expressed 3.3 kb guinea-pig H1 receptor mRNA. Expression of histamine H1 mRNA of guinea-pig peripheral organs was greater than that of rat organs, suggesting the high sensitivity of guinea-pig organs as to histamine is due to the contents of histamine H1 receptor mRNA. In addition, the lung, adrenal, intestine, and heart expressed 3.9 kb mRNA. In situ hybridization showed that the hippocampus, cerebral cortex, thalamus, and granular layer of the cerebellum each contained a large amount of histamine H1 receptors. Southern blot analysis showed that there was another gene quite similar to the cloned histamine H1 receptor gene.

Amino Acid Sequence↗
PubMed1992

Control of Drosophila Sex-lethal pre-mRNA splicing by its own female-specific product.

Drosophila melanogaster somatic sexual differentiation is accomplished by serial function of the products of sex-determination genes. Sex-lethal (Sxl), is one such gene. It is functionally expressed only in female flies. The sex-specific expression of this gene is regulated by alternative mRNA splicing which results in either the inclusion or exclusion of the translation stop codon containing third exon. Although previous genetic and molecular analyses suggest that functional Sxl expression is maintained by a positive feedback loop, where the female-specific Sxl product promotes the synthesis of its own female-specific mRNA, the mechanistic details of such regulation have remained unclear. We have developed a cotransfection system using Drosophila cultured (Kc) cells in which Sxl primary transcripts are expressed with or without the female specific Sxl product. Here we show that the female-specific Sxl product induces the synthesis of its own female-specific mRNA by negative control of male-specific splicing. Deletion, substitution, and binding experiments have demonstrated that multiple uridine-rich sequences in the introns around the male-specific third exon are involved in the splicing regulation of Sxl pre-mRNA.

Animals↗
PubMed1992

Binding of the Drosophila transformer and transformer-2 proteins to the regulatory elements of doublesex primary transcript for sex-specific RNA processing.

Sex-specific alternative processing of double-sex (dsx) precursor messenger RNA (pre-mRNA) is one of the key steps that regulates somatic sexual differentiation in Drosophila melanogaster. By transfection analyses using dsx minigene constructs, we identified six copies of the 13-nucleotide sequences TC(T/A)(T/A)C(A/G)ATCAACA in the female-specific fourth exon that act as the cis elements for the female-specific splicing of dsx pre-mRNA. UV-crosslinking experiments revealed that both female-specific transformer (tra) and transformer-2 (tra-2) products bind to the 13-nucleotide sequences of dsx pre-mRNA. These results strongly suggest that the female-specific splicing of dsx pre-mRNA is activated by binding of these proteins to the 13-nucleotide sequences.

Animals↗
PubMed1992

Failure to detect HTLV-I by in situ hybridization in the biopsied muscles of viral carriers with polymyositis.

Direct infection of muscle fibers by human T-lymphotropic virus type I (HTLV-I) has recently been reported in a patient with polymyositis infected with both HTLV-I and human immunodeficiency virus (HIV). Coinfections of these viruses are frequently found in the United States. In Kagoshima, Japan, patients with polymyositis have a significantly increased incidence of seropositivity to HTLV-I alone, when compared with the general population of Kagoshima. In this study, we examined muscle tissue from 6 HTLV-I-positive patients with polymyositis from Kagoshima. To detect HTLV-I products, sensitive immunohistochemistry and in situ hybridization analysis were performed. These were compared with muscle fibers from a well-characterized transgenic mouse model which expressed HTLV-I tax. No specific signals were detected in the biopsied muscles of patients with polymyositis infected with HTLV-I alone. HIV co-infection may, therefore, augment HTLV-I expression through either immunosuppression or direct viral interactions.

Adult↗
PubMed1992

Pathological changes in skeletal muscle in HTLV-I-associated myelopathy.

The main lesion site of HTLV-I-associated myelopathy or tropical spastic paraparesis (HAM/TSP) is the pyramidal tract. In some HAM patients, clinical symptoms and findings indicate neuromuscular involvement, such as muscular atrophy, fasciculation, elevated serum creatine kinase (CK) or significant electrophysiological data. Cases of HAM/TSP complicated with polymyositis or motor neuron disease have been reported. But no investigation has been directed to muscular pathology in many patients of HAM/TSP. We conducted muscle biopsies on 13 HAM patients. Four patients showed neurogenic changes. Six patients showed histological findings indicative of inflammatory myopathy. We investigated surface marker of invading cells in these 6 patients. In all patients, T lymphocytes were more predominant than B lymphocytes and in three of them T helper/inducer cells were more predominant than T suppressor cells. In 2 patients, only slight myopathic change could be seen, such as variation in fiber diameter and increase in the number of internal nuclei. In 1 patient, type 2 fiber atrophy was seen, and was possibly the result of disuse. Disturbance of secondary motor neurons or inflammatory myopathy is thus shown to be possibly associated with HAM/TSP.

Adult↗
PubMed1992

Muscular involvement in lysosomal acid lipase deficiency in rats.

We investigated the pathological and biochemical changes of skeletal muscle in rats with lysosomal acid lipase deficiency, which is an animal counterpart of human Wolman's disease. In the affected rats, the acid lipase activity for three different substrates, 4-methylumbelliferyl-oleate (18.9% of the normal control level), [14C]cholesteryl oleate (23.5%), and [14C]triolein (26.9%), was similarly decreased in the lysosomal fraction of skeletal muscle which was obtained by differential centrifugation. Histochemical studies showed that acid phosphatase activity was high in the endomysium and perimysium and in some muscle fibers. Some fibers showed vacuolar degeneration resembling "rimmed vacuoles". Ultrastructural studies demonstrated many membrane-bound lipid droplets in the muscle fibers, especially in the subsarcolemmal space, indicating that a low density lipoprotein (LDL) uptake pathway apparently existed in the muscle cells. However, such lipid accumulation was much greater in the interstitial cells and the endothelial cells. This distribution also suggests that LDL/cholesterol is supplied to muscle cells predominantly through endothelial cells.

Animals↗
PubMed1992

Experimental simvastatin-induced myopathy in rabbits.

We induced experimental myopathy in rabbits by giving simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor. After oral administration of simvastatin (50 mg/kg/day) for 2 weeks, serum CK was elevated in 5 of 7 rabbits; degenerating or necrotic fibers were seen in 3 rabbits. Using electromyography, myotonic discharges were found in the 2 rabbits examined. The combination of myotonic discharges, necrosis and raised serum CK levels suggests that the myopathy was induced by lesions of the muscle surface membrane.

Administration, Oral↗
PubMed1992

Lymphocyte subsets in muscle biopsies of human T-lymphotropic virus type I carriers with polymyositis.

Recent epidemiologic studies have shown that human T-lymphotropic virus type I (HTLV-I) is associated with polymyositis. To clarify the histological features of HTLV-I positive polymyositis, we studied muscle tissue from two groups of patients with polymyositis, those seropositive for HTLV-I (5 patients) and those seronegative (5 patients). We examined the lymphocyte subsets in muscle biopsies using monoclonal antibodies. In the endomysium, a variable number of T-lymphocytes and macrophages and a smaller proportion of B-lymphocytes were found in both groups. In both HTLV-I positive and negative patients a variable number of T-lymphocytes and macrophages, with a smaller number of B-lymphocytes, were found in the perimysium. As a whole, the T-lymphocytes were predominantly of the helper/inducer phenotype in both groups. We failed to find any specific phenotype distribution among T-cells infiltrating the muscle of HTLV-I carriers with polymyositis.

Adult↗
PubMed1992

[Clinical and histochemical findings in spinal muscular atrophy].

The childhood form of the spinal muscular atrophy (SMA) is classically subdivided into three groups on the basis of a combination of age of onset, milestones of development and age of survival: acute Werdning-Hoffmann (type I), intermediate Werdnig-Hoffmann (type II) and Kugelberg-Welander disease (type III). Now we examined 7 cases of type I and 9 cases of type II on clinical and histochemical ground. Of the total of 16 cases, 5 cases had a family history of the disease. (1) In type I, three were males and 4 females. The onset was within 30 days and the disease was manifest before or at delivery in 3 cases. The progression was so severe. All cases were dead by 10 months. They showed generalized hypotonia, abnormal respiration and could not sit without support. In type II, five were males and 4 females. The onset of the disease was between the age of 3 and 15 months. The progression was slow. All patients couldn't walk by themselves at all but 7 of them had abilities to sit without support. Clinically it was easy to classify type I from type II. (2) The most characteristic histochemical findings of both types were group atrophy, fiber hypertrophy, fiber type predominance and fibrosis. Though there was a slight difference between two types in histological pattern, the basis was so similar. There is controversy about the proper classification of recessive childhood SMA. Now it is suggested that the majority of both acute and chronic cases are allelic, similar to the patterns of Duchenne and Becker forms of muscular dystrophy.

Biopsy↗
PubMed1992

Neuropathology of HTLV-I-associated myelopathy--a report of two autopsy cases.

A neuropathological analysis was performed in two autopsy cases of HTLV-I-associated myelopathy. The thoracic spinal cords were most severely affected and the histopathological findings consisted of mononuclear cell infiltration, marked destruction of myelin and axons and astrocytic gliosis. More than half the infiltrated cells were positive for pan-T cell marker; B cells were sparse in the parenchyma and subarachnoid spaces. CD4 and CD8 positive cells were found in the early stages of the lesions. CD8, however, predominated over CD4 in the other stages. It appeared that a chronic inflammatory process had started at the middle to lower thoracic cord and had extended gradually in both directions. The middle thoracic spinal cord is known to have the poorest blood supply, and the horizontal distribution of inflammatory cells at this region correlated with the most distal supply of the anterior spinal artery.

Aged↗
PubMed1992

[Clinical significance of serum cardiac myosin light chain I in patients with Duchenne muscular dystrophy].

The cardiac myosin light chain I (LCI) is one of the cardiac muscle structural proteins. A sensitive immunoradiometric assay kit for LCI by using LCI monoclonal antibodies is developed. We estimated LCI in the patients with Duchenne muscular dystrophy (DMD) and Kugelberg-Welander disease (KW). The results suggested that LCI has close relationships with the functional disturbances of skeletal muscles, especially disturbances of pulmonary ventilation. Therefore we studied properties and localizations of LCI in the skeletal muscles by Western blotting and immunohistochemical methods. In Western blotting method LCI monoclonal antibodies have a band of 27 KD proteins of skeletal muscles. LCI has also found to be localized in type 1 fibers in frozen sections of biopsied of human skeletal muscles. LCI was measured from 47 patients with DMD and 8 patients with KW. The average serum LCI levels in the patients with DMD were 11.79 ng/dl and its levels in the patients with KW were in the normal range (under 2.5 ng/dl). Among 12 patients receiving negative pressure chest respirator, the levels of LCI were also under 2.5 ng/dl. Serum LCI decreased with increasing age and reduced physical activity. The levels of LCI has obvious positive correlations with CK and myoglobin. These results suggested that the measurements of serum LCI are useful as one of the markers of disease severity and the determination of suitable time of using respirator.

Adolescent↗