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Biomedical subjects

Y Nishimura

Publications and source records attributed to Y Nishimura.

At least 1,135 records · Page 63Linked to original sources
PubMed1983

Postnatal development of circadian rhythm in serum cortisol levels in children.

High-pressure liquid chromatography was used to study the development of blood adrenocortical circadian rhythm in a total of 64 children, ranging in age from 1 month to 15 years. Patients with endocrine diseases, congenital anomalies, and diseases of the central nervous system were excluded from this study. Determination of corticosteroid concentration was possible with 20 to 100 microL of serum. Twenty-four hour patterns were determined at six-hour intervals. A distinct circadian rhythm with an amplitude comparable to that of an adult emerged at approximately 6 months of age.

Adolescent↗
PubMed1982

Isolation and characterization of an Escherichia coli mutant lacking tRNA-guanine transglycosylase. Function and biosynthesis of queuosine in tRNA.

An E. coli mutant that lacks tRNA-guanine transglycosylase was isolated by random screening from a collection of Escherichia coli mutants obtained with N-methyl-N'-nitro-N-nitrosoguanidine. The defective gene, named tgt, was mapped at about 9 min on the E. coli chromosome, and the gene order was shown to be phoB-tgt-tsx. tgt was transferred to an E. coli strain with a defined genetic background by P1 transduction to investigate its function. The mutant thus obtained lacked queuosine (2-amino-5-[3S, 4R, 5S)-4,5-dihydroxycyclopent-1-en-3-ylaminomethyl]-7-(beta-D-ribofuranosyl)-pyrro lo-[2,3-D]-pyrimidin-4-one) in tRNA, indicating that the enzyme is actually involved in the biosynthesis of queuosine in tRNA. No clear biological defect was observed in the mutant, and, in fact, it grew slightly faster than the control isogenic strain. tRNATyr lacking queuosine, isolated from the mutant, showed no significant biological difference from normal queuosine-containing tRNA in amino acid acceptor activity or amino acid transfer in a cell-free protein synthesizing system directed by synthetic polynucleotide. The only phenotypic change observed in the mutant thus far is marked reduction of viability when the cells are kept under unsuitable conditions for growth, suggesting that the presence of queuosine in tRNA is important to E. coli for survival in the natural environment.

Escherichia coli↗
PubMed1982

Hemiparesis with multiple periventricular enhancing lesions on cranial CT.

A 23-year-old woman had progressive right hemiparesis followed by spontaneous clinical remission. The clinical profile and multifocal contrast-enhancing CT lesions in the periventricular region of the cerebrum favored the diagnosis of an acute demyelinating process. Serial examinations showed resolution of CT abnormalities. Right internal carotid angiography showed prominent deep draining medullary veins with fleck-like stains. The angiographic appearances might reflect vascular involvement in the demyelinating process.

Adult↗
PubMed1982

Metastatic tumours of the mouth and jaws. A review of the Japanese literature.

A review of the Japanese literature revealed 41 well-documented metastatic tumours of the mouth and jaws. The incidence was 1.5 times higher in females than in males and 76% were in the fourth to seventh decades with a mean of 44 years. Instead of the breast which is the most frequently encountered site of origin of metastatic tumours in Caucasians, the uterus followed by the lung, kidney and stomach was the site of primary carcinoma with the highest incidence. Histologically, carcinomas of glandular origin showed the highest rate of metastasis which was followed by choriocarcinomas. Squamous cell carcinoma and sarcoma were unusual. Metastasis occurred in the gingiva in 23 cases and bony involvement was noted in 16 cases. The most common symptoms were swelling, pain, bleeding, paraesthesia and loosening of teeth. The radiographic appearance was quite variable with no specific diagnostic characteristics. The oral lesions were treated by surgery, irradiation or chemotherapy in 32 cases, while no treatment was carried out in seven cases. Prognosis was very poor with 33 fatal cases due to multiple metastases.

Adolescent↗
PubMed1982

Radioactive iodination of lymphocyte surface proteins and characterization of their molecular properties.

Two radioiodination methods for surface proteins on mouse lymphocyte membrane, that is, the lactoperoxidase method and the chloramine T method, were comparatively investigated. The extents of iodination under various conditions were determined by measurements of radioactivities incorporated into the cell fractions and into the protein components isolated by specific immunoprecipitation from lyzates of the labeled cells. It was demonstrated that the chloramine T method, as well as the lactoperoxidase method, was applicable to label the lymphocyte surface proteins without any significant labeling of the cytoplasmic proteins. It was also found that the iodination efficiencies of the membrane immunoglobulin polypeptide chains in these two labeling methods were different in each of the isotopes, mu and delta chains. The possibility that the differences are related to their primary structures and to their exposure or anchorage profiles on the cell membrane is discussed with reference to the reaction mechanisms of the two labeling methods.

Animals↗
PubMed1982

Lifetime of tyrosine fluorescence in nucleosome core particles.

The fluorescence intensity and fluorescence lifetime of the tyrosine residues in calf thymus nucleosome core particles have been determined as functions of the ionic strength of the solvent. For interpreting the results, in the first approximation, the 30 tyrosine residues involved in the particle are classified into two groups. About 12 belong to class I; they are distributed in the protein core with an average distance of 2.0 nm from its center. In the intact particle (in 20 mM to 0.4 M salt solution), a Förster-type energy transfer is considered to take place from these class-I tyrosine residues to the DNA bases, but this no longer occurs on elevating the salt concentration to about 1.4 m. The remaining tyrosine residues (about 18, called class II) are considered to be involved in hydrogen bonds or in some other intramolecular interactions in the intact core particles, so that their fluorescence is completely quenched. On elevating the salt concentration to 2.0 M, this quenching is partially removed. Implications of these dynamic and static quenching are discussed in terms of the structure of the core particle.

Animals↗
PubMed1982

Micro-environment of the H3-H3 contact region of a nucleosome core particle, as revealed by a lifetime measurement of a fluorescent probe.

A sample of fluorescently-labeled nucleosome core particles was prepared by combining N-(3-pyrene)-maleimide to each of the two cysteine residues of the two H3 histones in the chicken erythrocyte nucleosome core particle, by a method previously reported by Zama et al. (Nucl. Acids Res. 5, 3881 (1978)). The fluorescence spectra and fluorescence lifetime of the sample in solvents with various Na+ concentrations have been examined. Three different types of micro-environment of the fluorescent probe have been found: (i) emits a pyrene dimer fluorescence at 460 nm, (ii) emits a pyrene monomer fluorescence with a long (75-65 ns) lifetime, and (iii) emits a pyrene monomer fluorescence with a short (5-15 ns) lifetime. The manner of dislocation of the two H3 subunits from each other in each of the solutions with different salt concentrations was discussed.

Animals↗
PubMed1982

Whole-body retention and tissue distribution of 60Co in rats after oral administration of freshwater fish contaminated with 60Co.

The purpose of this report is to compare the whole-body retention and tissue distribution in rats of 60Co administered by gavage as inorganic 60CoCl2 or in a form incorporated into freshwater fish. Orizias latipes were placed in vessels containing 21. of tap water with radioactive cobalt. Periodically thereafter the fish were sacrificed, homogenized, and administered to rats via a stomach tube. Control groups of rats were given the radionuclide alone or together with a homogenate of nonradioactive fish. The whole-body retention and tissue distribution of the radionuclide were determined with an Armac counter. The results revealed that rats gavaged with 60Co incorporated into the fish retained much more 60Co than control rats. This trend was notable in rats given fish kept in radioactive solution for longer periods. Marked differences in tissue distribution of 60Co were also observed between rats given 60Co incorporated into fish and control rats.

Animals↗