Search PubMed⌕ Search

Biomedical subjects

S Ohta

Publications and source records attributed to S Ohta.

At least 811 records · Page 45Linked to original sources
PubMed1984

A purified precursor polypeptide requires a cytosolic protein fraction for import into mitochondria.

The beta-subunit of mitochondrial ATPase is coded by a nuclear gene, synthesized outside the mitochondria as a larger precursor and imported into mitochondria. The beta-subunit precursor was purified from yeast, both as a homogeneous, unlabeled polypeptide and in radiochemically pure form. Both precursor preparations were cleaved to the mature beta-subunit by partially purified processing protease from the mitochondrial matrix. However, import of the radiochemically pure precursor into isolated yeast mitochondria required a cytosolic fraction from yeast or reticulocytes. The cytosolic factor was non-dialyzable and trypsin-sensitive; its apparent mol. wt. was approximately 40 000 as judged by gel filtration. Import of some proteins into mitochondria thus requires proteins of the 'soluble' cytoplasm.

Biological Transport↗
PubMed1984

Intracranial hemorrhage in the full-term neonate and young infant: correlation of the location and outcome.

The cranial computed tomography (CT) and outcome for 13 full-term neonates and 12 young infants with intracranial hemorrhage (ICH) were studied. The full-term neonates had perinatal asphyxia or neurological signs such as seizures. All infants were breast-fed and showed bleeding diathesis. In the full-term neonates there was a high incidence of intraventricular hemorrhage (IVH) and hemorrhage around the falx. The location of the hemorrhage on CT and brain pathology suggested that the original site of IVH might be the choroid plexus vessels in the lateral ventricle or in the subependymal layer. On the other hand, the sites of ICH in infants were multifocal compared with those in full-term neonates. Subdural hemorrhage (SDH) was seen more frequently and IVH less frequently in infants than in full-term neonates. The cases with SDH frequently showed accompanying cerebral infarction followed by porencephaly. Thus, SDH with cerebral low density on CT may predict a poor prognosis.

Brain↗
PubMed1984

Morphologic study of cytoskeletal systems of mouse hepatocytes using polyethylene glycol-embedding method.

SM mouse livers extracted by immersion in 1% Triton X-100, or in 1% Triton X-100 followed by 0.3 M KI were studied electron microscopically using the polyethylene glycol-embedding method. After extraction with 1% Triton X-100, almost all the structural components of hepatocytes remained intact and cytoplasmic filaments could be seen three-dimensionally by using stereopairs of micrographs. It was difficult, however, to discriminate microfilaments, intermediate-sized filaments and microtubules from one anoter in these specimes . By immersion in 1% Triton X-100 followed by 0.3 M KI, hepatocytes were extracted remaining only plasma membranes, vesicles and filaments. These filaments were approximately 10 nm in diameter, that is intermediate in size. They were branched and were connected with plasma membranes, especilly at desmosomes. The combination method of immersion extraction and PEG-embedding seems to be suitable for the electron microscopic observation of the cytoskeleton of cells in situ.

Animals↗
PubMed1983

Melting of local ordered structures in yeast 5S ribosomal RNA in aqueous salts.

Equilibrium and kinetics of thermal melting of yeast 5S ribosomal RNA in aqueous NaCl with or without Mg2+ were investigated by differential thermal melting and temperature jump methods. Two peaks (1 and 2) and a shoulder were observed in each of melting curves at ionic strength I=0.002-0.5 and linearity between each of melting temperatures T1m and T2m and log I was found at I=0.01-0.5 in the Mg2+-free solution. The local structures were found to be stabilized considerably by Mg2+. The temperature jump measurements gave the kinetic melting curve of the structure 1 at I=0.03 without Mg2+ or with 0.5 mM Mg2+. The kinetic Tm coincided well with the corresponding static Tm. For the structure 1, various parameters were calculated from the kinetic data, which indicated a double helical character of the structure 1. In terms of the values of Tm, G-C content, and enthalpy change of the transition of the structure 1 or 2, appropriateness of each of the secondary structure models of eukaryotic 5S RNA proposed previously was discussed.

Hot Temperature↗
PubMed1983

Uniform DC electric field exposure systems for mice and cats.

In most previous 50/60-Hz experiments, subjects were placed in a dielectric cage and the electric field was applied from outside the cage. Although the field outside the cage was kept uniform in space and constant in time, the field inside the cage undergoes undesirable temporal and spatial variations. We have designed an electric-field exposure system that overcomes these problems by having a metal cage constitute a part of the field generating electrodes. The uniformity along the diameter of the cages for mice and cats are more than 84.2% and 74.3%, respectively.

Animals↗
PubMed1982

The pathogenesis of abnormal cytoarchitecture in the cerebral cortex and hippocampus of the mouse treated transplacentally with cytosine arabinoside.

Pregnant mice were treated with cytosine arabinoside on days 13.5 and 14.5 of pregnancy. Brains of the offspring were studied histologically. The matrix layer of the embryonic brains was extensively destroyed 12 h after the injection of cytosine arabinoside, but regenerated partially on day 17 of gestation. In the cerebral cortex of 1-, 3-, and 5-day-old treated mice, abnormal clusters of young neurons were found on the surface of the developing cerebral cortex. Some clusters still had a supply of immature neurons from the remnants of the regenerated matrix layer. After 20 days, the clusters became gradually indistinct, although some vestigial groups of neurons were observed even after 120 days. In the hippocampus of young mice, the pyramidal cells decreased in number and were disarranged. Heterotopic pyramidal cell masses were found in the stratum radiatum and in the molecular layer of the dentate gyrus. Apical dendrites of pyramidal cells exhibited abnormal arborization. It was demonstrated by 3H-thymidine autoradiography that young neurons in the abnormal clusters in the cerebral cortex were those produced in the matrix layer regenerated after the destructive change by cytosine arabinoside.

Abnormalities, Drug-Induced↗
PubMed1982

Epidermal origin of the amyloid in localized cutaneous amyloidosis.

A case of localized cutaneous amyloidosis which developed after a lichen planus-like skin reaction is reported. The amyloid consisted of amyloid fibrils enveloped by heparan sulphate granules. These amyloid fibrils reacted to anti-human keratin antibody, indicating an epidermal origin for the fibrils.

Aged↗
PubMed1982

Ultrastructure of intracytoplasmic inclusion bodies in hepatocytes of griseofulvin-treated mice. Fibrils with myelin figure and rod-like fibrils.

Intracytoplasmic eosinophilic inclusion bodies light-microscopically identical to human alcoholic hyalin were produced in hepatocytes of griseofulvin-treated mice. Electron-microscopic investigation on these inclusion bodies revealed two morphologically different fibrils. The most frequently observed fibrils in liver tissues appeared straight or slightly curved in longitudinal sections and granular in cross sections. High-power electron micrographs on these fibrils revealed that each fibril consisted of parallel-running fine filaments of about 1.25 nm thick which were separated by spaces of about 1.25 nm. The ultrastructural appearance of these fibrils resembled that of myelin sheath in longitudinal sections. They usually measured from 13 to 32 nm wide and up to 0.9 micron long. Fibrils with larger diameter of up to 62 nm were infrequently encountered. Rod-like fibrils ultrastructurally similar to those seen in human alcoholic hyalin were also found in isolated materials. All these fibrils were isolated in the same fraction by a slight modification of a discontinuous sucrose gradient ultracentrifugation and a two phase polymer centrifugation. The present observation suggests that intracytoplasmic inclusion bodies produced in this animal model are composed of morphologically different fibrils. These different fibrils could share the same origin.

Animals↗