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Biomedical subjects

S Maeda

Publications and source records attributed to S Maeda.

At least 1,009 records · Page 56Linked to original sources
PubMed1980

Pathology of experimental radiation pancarditis. I. Observation on radiation-induced heart injuries following a single dose of x-ray irradiation to rabbit heart with special reference to its pathogenesis.

Radiation-induced heart injuries were morphologically studied by using the rabbits irradiated with a single dose of 3,000R (group I) or 300R of X-ray group II) from 1 hour until 6 months. There was no essential difference in the lesions of the hearts from group I and that of group II. Acute epicarditis was found as early as 1 hour after irradiation and it became maximum in severity at 1-2 days. In the myocardium, there were degeneration and resolution of the myocardial cell, various architectural changes of mitochondria, and disorganization of the intercalated disc. Polymorphonuclear cell infiltration and endothelial injuries of the capillaries occurred in the interstitial tissue. In addition, endocarditis with or without thrombus formation was often found. Acute inflammation was seen in the myocardium of group II rather later than that of group I, but it disappeared earlier. In the later stage, fibrosis finally occurred in the epicardium and endocardium. Glycoprotein degeneration of the muscle cells and fibrosis appeared in the myocardium. The pathogenesis of radiation pancarditis is thought to be dependent not only on the disturbance of microcirculation caused by endothelial cell damage of the capillaries, but also on alterations of the myocardial mitochondria as a result of direct injury.

Animals↗
PubMed1980

Quantitative estimation of nucleolar cistrons (rDNA) in proliferating normal and tumor cells.

The saturating hybridization levels of DNA with rRNA (hereafter abbreviated as rDNA/DNA) in adult liver, bone marrow, and fetuses in Long-Evans rats were 0.042, 0.036, and 0.029 approximately 0.033%, respectively, showed a lower level in rapidly growing tissues. We consider that the lower rDNA/DNA in rapidly growing tissues might be due to the replication of rDNA in the late S phase, or in other words, to the depression of rDNA/DNA in each S phase. Based on these findings, the relative levels of rDNA per G1 geome were estimated in cells of these normal tissues and 4 diploid tumors by multiplying rDNA/DNA and DNA/genome. By this procedure, rDNA/genome was shown to be constant in normal G1 cells, while a 31 approximately 48% increase was found in the tumor cell genome. Direct measurement of rDNA in synchronized #2 trisomy leukemia cells confirmed the replication of rDNA in the late S phase, with a 21.4% increase of rDNA per G1 genome.

Animals↗
PubMed1979

Stimulation of thiamine diphosphatase activity by ascorbic acid in rat brain microsomes.

The effect of ascorbic acid on microsomal thiamine diphosphatase activity in rat brain was examined. Ascorbic acid at 0.02--0.1 mM increased the thiamine diphosphatase activity by 20--600% and produced a significant amount of lipid peroxide, which was measured with thiobarbiturate under the same conditions as the enzyme. A lag period of about 10 min was observed in the process of stimulation of enzyme activity by ascorbic acid. The stimulation of enzyme activity and the lipid peroxidation induced by ascorbic acid were blocked by metal-binding compounds (EDTA, alpha,alpha'-dipyridyl, o-phenanthroline) and an antioxidant (N,N'-diphenyl p-phenylenediamine). GSH significantly enhanced the stimulation of enzyme activity and formation of lipid peroxide by 0.02--0.05 mM ascorbic acid. The effect of GSH was due in part to maintenance of the concentration of ascorbic acid in the medium, since GSH could convert dehydroascorbic acid, an oxidized form of ascorbic acid, to ascorbic acid.

Animals↗
PubMed1979

An electron microscopic study on the lining mucosa of developing rat vocal cords.

To explain the developmental process of epithelial cells of true vocal cords, larynges obtained from 42 fetal and 36 developing young rats were examined using scanning and transmission electron microscopies. Although the membranous portion was indistinguishable from the arytenoid portion in the prenatal stage, there was no squamous cell epithelium on the glottis. The lining epithelium of vocal cords in 15, 16, and 17 day fetal rats was composed of cuboidal and columnar cells which had a primary cilium. Immediately after birth the membranous portion of vocal cords became recognizable, and ciliated cells present on vocal cords retrogressed rapidly while nonciliated squamous cells grew and extended. Results of the present study show that epithelial cells of ciliated columnar type covering vocal cords change remarkably to nonciliated squamous cells between prenatal and postnatal stages.

Animals↗
PubMed1979

Widespread eczema vaccinatum acquired by contacts. A report of an autopsy case.

A 4-month-old male infant predisposed to allergic dermatitis acquired wide-spread eczema vaccinatum by contacts with a recently vaccinated sibling. He died of acute purulent peritonitis following a perforation of multiple duodenal ulcers. Fluorescence immunocytochemical and electron microscopic studies on the skin lesions revealed the presence of viral antigens and numerous virus particles compatible morphologically with those of the mature form from the same batch of smallpox vaccine given to the sibling. A large number of virus particles in the developmental form were also predominantly scattered in the cytoplasm of cells at the stratum malpighii of the epidermis as well as in neutrophils and macrophages in the skin lesions. The virus isolation from the skin lesions was done by using the HeLa cells and the human embryonic lung fibroblasts. No abnormal laboratory data were noted in immunoglobulins. On the basis of atrophy of the thymus and other lymphatic tissues and an appearance of large pyroninophilic cells in association with blastoid transformation, the authors discussed a possible participation of the disturbance of cellular immunity secondary to the virus infection in the development of the disease.

Antigens, Viral↗
PubMed1979

Vein graft bypass in treatment of giant aneurysm.

A case of giant internal carotid artery aneurysm which was successfully treated by trapping and internal decompression of the aneurysm is presented. Proximal vascular occlusion of the involved internal carotid artery and long vein bypass graft were performed under hypothermia. This is the first long vein bypass graft reported for the treatment of a giant aneurysm.

Adult↗
PubMed1978

Factors involved in differential Giemsa-staining of sister chromatids.

Microspectrophotometric evaluation of differentially stained sister chromatids made it possible to analyse precisely the factors involved in the Giemsa methods. The concentration of Hoechst 33258, pH of the mounting medium temperature during UV-exposure and the quality (wavelength)of UV-light influenced the differential staining. Exposure of blacklight of 10(-5) M Hoechst 33528-stained brdU-labeled chromosome specimens mounted in McIlvaine buffer (pH 8.0) at 50 degrees C reproducibly allowed differential staining of sister chromatids within 15 min. On the other hand, Korenberg-Freedlender's method using no Hoechst 33258 was also UV-light-dependent. Thus, photolysis of BrdU-substituted DNA was considered the basic mechanism of the Giemsa methods where the photosensitive Hoechst 33258 played a role as a sensitizer.

Azure Stains↗
PubMed1978

Control of normal differentiation of myeloid leukemic cells. XIII. Inducibility for some stages of differentiation by dimethylsulfoxide and its disassociation from inducibility by MGI.

There are clones of myeloid leukemic cells that can be induced to differentiate by the normal differentiation-inducing protein MGI to form Fc and C3 rosettes, mature macrophages and granulocytes. One of these clones (MGI+DMSO+) was also inducible by dimethylsulfoxide (DMSO) for C3 but not Fc rosettes, and for mature macrophages but not for mature granulocytes. Other clones (MGI+DMSO-) were inducible by MGI but not DMSO and a third type of clone (MGI-DMSO-) was not inducible by either compound. Clones that differed in their inducibility by DMSO showed a similar inhibition of cell multiplication by DMSO. The results indicate, that some stages of differentiation can be induced by DMSO in an appropriate clone of myeloid leukemic cells and that there are different cellular sites for induction by DMSO and MGI.

Cell Differentiation↗
PubMed1978

Studies on immunoreactive gastrin with special regard to its molecular form and G cell counts in gastrointestinal mucosa of fetal, neonatal and adult rats.

Changes of distribution of immunoreactive gastrin (IRG) and molecular forms of intra-tissue gastrin in the growth course of rats were examined. The results obtained were as follows; 1) IRG concentrations and G cell counts were extremely low in the fetal antral mucosa. However, a gradual increase of the above was observed during the neonatal suckling period, accompanied by a rapid increase at the commencement of feeding. 2) IRG concentrations in the duodenal mucosa of the fetal and neonatal period were markedly higher than that of adult rat. 3) Jejunal IRG concentration was negligible in the fetal period. The value obtained from the postnatal rats was equal to or higher than that of adult rat. 4) The major form of antral gastrin was G-17 throughout the fetal and adult age. No qualitative change of antral IRG in the growth course of rats was seen. 5) The major form of the duodeno-jejunal mucosa was G-17 in the fetal period and thereafter G-34 increased gradually in the growth course of rats. These results suggested that, (1) suckling and feeding appeared to be a trigger of the production and release of antral gastrin in the growth course of rats. (2) In the initial stage of the growth, G cells distributed in the duodeno-jejunal mucosa as well as in the antral mucosa may participated in the production and release mechanism of gastrin.

Animals↗
PubMed1978

Colicinogenic mutant of ColE1 plasmid that fails to confer immunity to colicin E1.

Insertion of the ampicillin transposon (Tn3) into ColE1 DNAs causes various mutations in the plasmids. Escherichia coli K-12 cells carrying one of these mutants showed novel properties; they were sensitive to colicin E1 and were able to produce active colicin E1. The site and the orientation of Tn3 insertion in this mutant ColE1 DNA were determined by heteroduplex analysis and by enzymatic digestion with restriction endonucleases. The potential usefulness of this mutant ColE1 DNA as a cloning vehicle is discussed.

Ampicillin↗
PubMed1978

The analysis of the intracranial pressure by the concept of the driving pressure from the vascular system.

In order to understand the pathogenesis of intracranial hypertension, the intracranial pressure (ICP) has usually been studied with the concept of volumetric pressure. In other words, the ICP is held to derive from the volume of the intracranial elements (e.g., brain, blood and cerebrospinal fluid). In this paper, the authors propose a new concept of the so-called driving pressure and apply it to both clinical and experimental studies. The driving pressure (DP) consists of the combined pressure continuously exerted on the ICP by the arterial pressure (ADP) and venous pressure (VP) systems.

Adolescent↗