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Biomedical subjects

S Okada

Publications and source records attributed to S Okada.

At least 1,261 records · Page 70Linked to original sources
PubMed1984

Synchrotron system for monochromatic uv irradiation (greater than 140 nm) of biological material.

An irradiation system of monochromatic uv radiation down to the wavelength of 140 nm was constructed for biological irradiation experiments in the vacuum-uv range using synchrotron radiation (SR) from the electron storage ring. The system consists of premirror chamber, vacuum-uv monochromator, irradiation chamber, and vacuum systems. Along with the detailed description of all components of the system, the installation at the storage ring and the performance characteristics are presented.

Particle Accelerators↗
PubMed1984

Radiation-induced DNA damage and cellular lethality in cultured mammalian cells.

X ray-induced DNA scissions and their repair were studied by an alkaline separation method. DNA damage in Chinese hamster V79 cells was assigned to one of three groups based on a repair profile previously used for mouse L5178Y cells: fast-reparable (T1/2 = 5 min), slow-reparable (T1/2 = 70 min), and nonreparable . The three kinds damage were investigated in relation to cellular lethality under conditions where radiosensitivity of cultured cells was modified: (1) different sensitivity in different cell lines, (2) cell cycle fluctuation of radiosensitivity, and (3) recovery after split-dose irradiation. Among the three types of lesions, only nonreparable damage or remaining lesions showed correlation to cell killing. The parallel relationship between nonreparable damage and cell killing implies that this type of damage could play an important role in radiation-induced cell death.

Animals↗
PubMed1983

Study of ammonia metabolism in a patient with ornithine transcarbamylase deficiency using an 15N tracer.

Ammonia metabolism was studied in an 8-year-old girl with ornithine transcarbamylase (OTC) deficiency, using 15N-tracer. Changes in the incorporation of 15N into amino acids and urea were examined after 15NH4Cl administration. The recovery of total 15N in the urine of the patient in 3 days was 28.5% of the administered 15N whereas that of a control was 69.3%. They were mostly urea. The recovery of 15N-urea in the patient was 28.8% of the control in 1 day, 32% in 2 days and 33.3% in 3 days after the administration of 15NH4Cl. A larger amount of 15N was incorporated into glutamine (alpha-amino N) and glutamate and 15N was incorporated more rapidly into alanine, asparagine and serine in the patient than in the control. The incorporation into ornithine was less in the patient than in the control.

Amino Acids↗
PubMed1983

Application of epithelial cells in culture to the biochemical studies of lysosomal hydrolase deficiencies.

Epithelial cells are readily obtained when the primary culture of skin fibroblasts is established. The major lysosomal hydrolase activities in normal epithelial cells are lower than those in normal fibroblasts. The primary deficiency of lysosomal enzymes can be detected both in epithelial cells and in cultured skin fibroblasts. However, epithelial cells of I-cell disease show only beta-galactosidase deficiency. This result indicates that epithelial cells have different biochemical properties from skin fibroblasts and they may be similar to those of visceral organs. Therefore, cultured epithelial cells seem to be useful for the studies on lysosomal hydrolase deficiencies.

Cells, Cultured↗
PubMed1983

A severe infantile sialidosis (beta-galactosidase-alpha-neuraminidase deficiency) mimicking GM1-gangliosidosis type 1.

We observed a 3-month-old Japanese female infant with severe psychomotor retardation, coarse facial appearance, hepatosplenomegaly, and dysostosis multiplex. Only beta-galactosidase was found to be deficient when the routine lysosomal hydrolase assay was performed on the patient's lymphocytes at 6 months of age. At first GM1-gangliosidosis type 1 seemed the most likely diagnosis. Later, however, additional studies (hydrolase assay in cultured skin fibroblasts, urinary oligosaccharide analysis, genetic complementation study, etc.) revealed that biochemical data of this case were in agreement with those of severe infantile sialidosis. The only important exception was that alpha-neuraminidase in the patient's lymphocytes showed normal activity but abnormal pH dependence toward 4-methylumbellyferyl substrate. In addition, a severely damaged kidney suggested that his case may be classified as a unique type of severe infantile sialidosis (possible nephrosialidosis). These observations stress the importance of careful biochemical diagnosis of a case with GM1-gangliosidosis type 1 phenotype.

Diagnosis, Differential↗
PubMed1983

Ultrastructural study on nervous system of fetus with GM1-gangliosidosis type 1.

The nervous system of a 22-year-old fetus with GM1-gangliosidosis type 1 was studied by electron microscopy. The tissues thus examined were the cerebral cortex at the parietal region, the cerebellum, the thoracic spinal cord, the Auerbach's myenteric plexus in the large intestine and the radial nerve fibers. In the cerebral cortex, membrane-bound vacuoles, which occasionally contained stacks of fine fibrils, were observed in the large young neurons in the deeper part of the cortical plate. The neurons in the other part of the cerebral cortex carried no storage materials. In the cerebellum, the membrane-bound vacuoles with stacks of fine fibrils were seen only in the Purkinje cells. The neurons in the spinal cord also contained several zebra-like bodies and the above membrane-bound vacuoles. As for the peripheral nervous system (PNS), neurons in the Auerbach's myenteric plexus carried membranous cytoplasmic bodies and zebra-like bodies. Some of the axons in the radial nerve fibers also contained a lot of pleomorphic electron-dense bodies and a few membranous cytoplasmic ones. These results show that the accumulation of storage materials is started in the large neurons which are produced in the early stage of neurogenesis in the central nervous system (CNS). Additionally, the observed membrane-bound vacuoles are considered to be structures which occur before the membranous cytoplasmic bodies and/or the zebra-like bodies. It is also elucidated that the PNS is affected earlier than the cerebral and cerebellar cortices and thoracic spinal cord.

Cerebellum↗
PubMed1983

Sialidosis type 2 in Japan. Clinical study in two siblings' cases and review of literature.

Clinical and biochemical findings in two siblings (24-year-old sister and 20-year-old brother), born to consanguineous parents, are described. Both showed progressive generalized myoclonus, macular cherry-red spots, moderate cerebellar ataxia, coarse facies, vertebral deformities, vacuolation of peripheral lymphocytes, bone marrow cells and epithelial cells of conjunctiva, but had normal intelligence. The excretion of sialyloligosaccharides in the urine of both was 3-5 times larger than in the controls. The activities of alpha-neuraminidase and beta-galactosidase in leukocytes and cultured skin fibroblasts were reduced. The clinical and biochemical findings were those of the newly described condition, sialidosis type 2. Review of all Japanese cases considered as sialidosis type 2 showed that the most characteristic clinical features as distinct from type 1, were coarse facies and bone deformities, especially of vertebral bodies.

Adult↗
PubMed1983

Mutations resistant to bromodeoxyuridine in mouse lymphoma cells selected by repeated exposure to EMS. Characteristics of phenotypic instability and reversion to HAT resistance by 5-azacytidine.

Mutations induced by repeated EMS treatments were investigated by using mouse L5178Y cells. The frequency of TGr mutations increased linearly with the number of EMS treatments whereas the yield of BrdUrdr mutations showed a curvilinear dose-response curve. The BrdUrdr frequency was roughly proportional to the square of the TGr frequency and the results were compatible with the hypothesis that BrdUrdr colonies isolated after 6 EMS treatments, however, were unstable. When BrdUrdr colonies that had arisen in BrdUrd medium after 2 weeks' incubation were isolated in normal medium, the descendant cells showed a nearly normal level of thymidine incorporation and low plating efficiencies of about 1% in BrdUrd medium. In contrast, after isolation of the same colonies in BrdUrd medium, a low level of thymidine incorporation and high plating efficiencies in BrdUrd medium were observed in the descendant cells. Reverse selection from BrdUrdr to HATr was accomplished with frequencies of 10(-6)-10(-3) for the descendants grown in BrdUrd medium, and AzaCyd treatment drastically increased the reversion frequency to nearly 10(-1). Further re-revertants from HATr to BrdUrdr were also found with frequencies of 10(-3)-10(-2) without treatment. These results indicate that the initial BrdUrdr cells did not result from inactivation of the thymidine-kinase gene but that the mode of gene expression was altered in some way.

Animals↗
PubMed1983

Zinc-induced hypocalcemia and bone resorption in rats.

The changes of calcium levels in serum and in the femur were examined in rats administered oral doses of zinc sulfate (0.1, 1.0, and 10 mg Zn/100 g body weight) for 3 days. All doses of zinc caused significant decreases in calcium levels in serum and in the femoral diaphysis and epiphysis. The decrease in these femoral calcium levels was seen 1 day after administration of zinc (10 mg/100 g). Furthermore, time course studies of the effect of zinc administration showed that, at 1 hr after zinc administration, calcium levels in serum and in femoral epiphysis but not in diaphysis were significantly decreased. In thyroparathyroidectomized rats, however, no significant decrease of the epiphyseal calcium was observed by administration of zinc (10 mg Zn/100 g), but the serum calcium level was significantly lowered. Zinc administration to intact rats caused a significant increase in acid phosphatase activity in the femoral epiphysis but not in the diaphysis. This increase was clearly prevented by thyroparathyroidectomy. Accumulations of zinc in the femoral epiphysis and diaphysis after zinc administration was not significantly altered by thyroparathyroidectomy. These results suggest that zinc-induced hypocalcemia may cause bone resorption which is primarily mediated by the action of the parathyroid hormone and it is related to calcium homeostasis in rats.

Acid Phosphatase↗
PubMed1983

Enhancement of ribonucleic acid synthesis by chromium(III) in mouse liver.

The effect of Cr(III) administration on hepatic RNA synthesis in mice was studied. It was found that Cr accumulated in mouse liver. Forty-eight hours after intraperitoneal injection of CrCl3 (0.005-5 mg Cr/kg body weight) approximately 10% of the administered dose per g of tissue remained. The accumulated Cr was still retained 64 days after administration (5 mg Cr/kg) with only a slight decrease. Approximately 20% of the hepatic Cr was detected in the nuclei. By administering CrCl3. RNA synthesis in mouse liver was markedly enhanced without altering the pool size of nucleotides. This enhancement was dose-dependent and statistically significant at doses of 0.05 (p less than 0.05), 0.5 (p less than 0.01), and 5 mg Cr/kg (p less than 0.01), and remained so for at least 16 days after administration of 5 mg Cr/kg. The synthesis of DNA and protein in mouse liver were not significantly changed by CrCl3 administration. On the other hand, Cr(VI) administration did not enhance but rather inhibited RNA synthesis in mouse liver. These results suggest that Cr(III) specifically enhances RNA synthesis in mouse liver.

Animals↗
PubMed1983

Bilateral intracranial granulomas as a complication of infected subdural peritoneal shunt.

Intracranial granuloma in childhood is considered to be a very rare disorder. A three-year-old child is described who had bilateral intracranial granulomas originating from the ends of bilateral subdural-peritoneal shunts. Serial computerized tomographic examinations revealed variable and peculiar findings. Since subdural-peritoneal shunt is used in neonate, intracranial granuloma must be considered as a potential complication of unremoved subdural-peritoneal shunt.

Brain Diseases↗