Hironori Tashiro

MELAS of infantile onset: mitochondrial angiopathy or cytopathy?

An 83-day-old male infant had convulsions, hypertrophic cardiomyopathy, and lactic acidosis. Cranial computed tomography revealed low-density areas in both parieto-occipital lobes and in the left temporal lobe. Muscle biopsy did not reveal ragged-red fibers, but abnormal mitochondria were found in the capillary endothelial cells as well as in the muscle fibers. At 5 months of age, the patient developed purpura on the soles and palms. Skin biopsy showed degeneration of the endothelial cells with abnormal mitochondria in the arterioles and capillaries. Myelinated nerves in the skin had vacuolated axons with swollen mitochondria, and their myelin sheaths showed vacuolation. At 9 months of age, he died of heart failure, and autopsy revealed abnormal mitochondria in the myocardium but not in the coronary vessels. Our findings indicate that the symptoms of the mitochondrial encephalopathy, myopathy, lactic acidosis, and strokelike episodes (MELAS) syndrome cannot be fully explained by the mitochondrial angiopathy alone.

Biological Relevance and Analysis of c-myc Gene Expression in Normal Human Ovary

Among oncogenes, the c-myc gene is most frequently activated in a wide spectrum of tumors (1). Recently, we demonstrated that the c-myc gene is overexpressed in primary human ovarian cancer tissues, especially in serous tumors (unpublished observation). The c-myc gene is also known to be involved in cell proliferation and differentiation other than carcinogenic process. It has been reported that granulosa cells in rat ovary express the c-myc transiently after pregnant mare serum gonadotropin (PMSG) administration, suggesting that the c-myc gene is involved in steroidogenesis (2). To elucidate the function of the c-myc gene in normal human ovary, c-myc expression was investigated by Northern hybridization and immunohistochemistry in 11 independent, normal ovarian tissues.