Mitsuo Midorikawa

Mitochondrial encephalomyopathies with the mutation of the mitochondrial tRNALeu(UUR) gene

Four families with mitochondrial encephalomyopathy are described. Probands of three families had typical clinical presentations of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS), but the proband of family 4 lacked strokelike episodes. The mitochondrial DNA mutation of tRNA(Leu(UUR)) (transfer ribonucleic acid specific to leucine (UUR codon)) found in MELAS was examined in muscle DNA obtained from biopsy samples of the probands of four families and the maternal relatives of family 2. The mutation was detected in all muscle samples, and the degree of the mutated DNA was 68% to 84% by Southern blot analysis. However, the clinical patterns of the maternal relatives of family 2 were mild and distinctly different from MELAS. The same mutation was also detected in blood-derived DNA samples of all family members examined, including healthy mothers but not fathers, although the degree of mutation did not correlate with the clinical severity. These results confirmed the maternal inheritance of this disease and suggested that the mitochondrial DNA mutation (tRNA(Leu(UUR))) may cause clinical symptoms other than MELAS. The clinical findings of mitochondrial encephalomyopathy should be reinvestigated in terms of the mitochondrial gene mutation; the polymerase chain reaction method will be useful for screening for this mutation of mitochondrial DNA in blood samples.

A case of Hallervorden-Spatz disease: Progressive and intractable dystonia controlled by bilateral thalamotomy

We present a 10-year-old girl with Hallervorden-Spatz disease diagnosed clinically from the neurological manifestations and the characteristic MRI findings. Her main symptom, dystonia, was progressive and resistant to medication, but this dystonia was controlled by bilateral thalamotomy. No clinical progression of the symptoms was recognized at 21 months from the last operation.

A case of chronic GM1 gangliosidosis presenting as dystonia : clinical and biochemical studies

SummaryClinical and biochemical studies are reported on a 32-year-old man with GM1 gangliosidosis who presented with a slowly progressive dystonia that began when he was aged 7 years and eventually became almost totally incapacitating at the age of 35. There was only mild intellectual deterioration, but myoclonus, seizures and macular cherry-red spots were never observed. Proton-density and T2-weighted MRI scans showed symmetrical hyperintense lesions of both putamina. No increase of GM1 ganglioside was found in plasma or cerebrospinal fluid, and the metabolism of GM1 ganglioside in cultured skin fibroblasts from the patient was also almost normal, although the residual activity of GM1 ganglioside β-galactosidase activity was only 10% of normal. These findings suggest that impaired GM1 ganglioside metabolism is not present systemically as it is in the infantile and juvenile types of the disorder, but is mainly confined to the central nervous system in chronic GM1 gangliosidosis.

The sensitivities to radiations and radiomimetic chemicals of cells from patients with ataxia telangiectasia

SummaryThe lethal action of physical and chemical agents on a fibroblast strain derived from a Japanese patient with ataxia telangiectasia (AT) was measured by the cellular colony forming ability, in comparison with a British AT cell strain. Both of the AT strains showed a significantly increased sensitivity to X-rays and an antitumor agent bleomycin, as compared with normal fibroblasts. Also, the two AT strains were slightly more sensitive to methyl methanesulfonate than normal cells. The British AT strain (AT4BI) exhibited a marked sensitivity to 4-nitroquinoline 1-oxide and to mitomycin C compared with normal cells, whereas the Japanese AT strain (AT1OS) showed normal response to 4-nitroquinoline 1-oxide and a reduced sensitivity to mitomycin C. Sensitivity of AT1OS cells to N-methyl-N′-nitro-N-nitrosoguanidine was also normal under our experimental conditions.

Uptake and metabolism of radiolabelled GM1-ganglioside in skin fibroblasts from controls and patients with GM1-gangliosidosis.

SummaryThe uptake and metabolism of [3-3H-sphingosine]GM1-ganglioside was measured in cultured skin fibroblasts from controls and patients with infantile, juvenile and adult GM1-gangliosidosis. When dissolved in medium with phosphatidylserine, GM1-ganglioside was efficiently taken up by cultured skin fibroblasts and transferred into lysosomes. A linear increase in GM1-ganglioside endocytosis was shown with phosphatidylserine concentrations of up to 40γm/ml. A pulse-chase study revealed that [3H]GM1-ganglioside was metabolized to GM2-ganglioside, GM3-ganglioside, ceramide dihexoside, ceramide monohexoside, ceramide and sphingosine. Sphingosine was recycled to sphingomyelin. In a 20-h pulse study, cell lines from patients with GM1-gangliosidosis of infantile, juvenile and adult types hydrolysed 2–5%, 20–44% and 54–58% of the total endocytosed GM1-ganglioside respectively. These values were lower than in control cells (64.17 ± 5.43% (n=10)). The hydrolysis rates of exogenous [3H]GM1-ganglioside in cultured fibroblasts from patients with various types of GM1-gangliosidosis closely reflected the clinical severity.

A case of pigmentary type of orthochromatic leukodystrophy with early onset and globoid cells

SummaryWe report herein a sporadic case of the pigmentary type of orthochromatic leukodystrophy with early onset and very rapid clinical course. The patients development was normal until 2 years old, when he experienced visual disturbance. Rapid deterioration resulted in death 1.5 years after the onset. Metachromatic leukodystrophy, globoid cell leukodystrophy and adrenoleukodystrophy were excluded by biochemical assays. Autopsy findings were compatible with the diagnosis of the pigmentary type of orthochromatic leukodystrophy. However, there were unique findings of severe neuronal loss and the collection of globoid-like cells in the interface of the gray matter and the white matter. Immunohistochemical staining of myelin basic protein, proteolipid protein and galactocerebroside demonstrated that these myelin constituents were equally preserved in the posterior column, while absent in the lateral and anterior columns of the spinal cord.

Study of pathogenesis in twitcher mouse, an enzymatically authentic model of Krabbe's disease.

The twitcher mouse was investigated by examining in vivo synthesis of galactosylceramide (Galcer) and galactosylsphingosine (Galsph) in a sciatic nerve culture, and in vitro enzymic activities for synthesis of Galcer and Galsph in the spinal cord from normal and affected mice. For the in vivo study, the sciatic nerve was incubated for 24 h in medium containing [3H]galactose, or [3H]-sphingosine-labeled Galcer or Galsph. With [3H]galactose, reduced synthesis of Galcer was found as early as 1 week of age and synthesis decreased to about 15% of normal value at 4 weeks. Increased Galsph was detected after 7 days of feeding with galactose. In a study of [3H]sphingosine-labeled Galcer and Galsph feeding, Galcer did not induce Galsph synthesis in either normal or affected mice, and synthesis of Galcer from Galsph was found only in normal mice, suggesting that Galcer was synthesized from sphingosine after hydrolysis of Galsph. In vitro, the activities of UDP-galactose: ceramide galactosyltransferase and UDP-galactose: sphingosine galactosyltransferase were reduced to less than 50% of control after 2 weeks of age in affected mice. We conclude that (1) decreased Galcer was due to impaired synthesis of Galcer, (2) Galsph was synthesized from galactose and not from deacylation of Galcer, and (3) Galsph accumulation was due not to increased synthesis but to decreased hydrolysis.

Diagnosis of Pompe's disease using pyridylamino-maltooligosaccharides as substrates of α-1,4-glucosidase

We have developed a sensitive method for the assay of alpha-1,4-glucosidase in cultured skin fibroblasts and muscle tissue using pyridylamino-maltooligosaccharides as fluorescent substrates. This method is useful for the diagnosis of Pompes disease.

Immunohistochemical Demonstration of GM2-Ganglioside in the Central Nervous System of a 19-week-old Fetus of Tay-Sachs Disease

Tay-Sachs disease (TSD, McKusick 27275) is an inherited neurodegenerative disorder due to the deficiency of β-hexosaminidase A (EC 3.2.1.52), which causes the accumulation of GM2-ganglioside (GM2) in the central nervous system (CNS) of the patients (O’Brien, 1983), but it remains unknown exactly when and where GM2 begins to accumulate in the affected tissues. We have studied its distribution in the CNS of a TSD fetus and an age-matched control by an immunohistochemical method in conjunction with the distribution of sphingolipid activator protein (SAP)-1, myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP).

Immunohistochemical Demonstration of GM2

Tay-Sachs disease (TSD, McKusick 27275) is an inherited neurodegenerative disorder due to the deficiency of β-hexosaminidase A (EC 3.2.1.52), which causes the accumulation of GM2-ganglioside (GM2) in the central nervous system (CNS) of the patients (O’Brien, 1983), but it remains unknown exactly when and where GM2 begins to accumulate in the affected tissues. We have studied its distribution in the CNS of a TSD fetus and an age-matched control by an immunohistochemical method in conjunction with the distribution of sphingolipid activator protein (SAP)-1, myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP).