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Biomedical subjects

M Tokunaga

Publications and source records attributed to M Tokunaga.

At least 289 records · Page 16Linked to original sources
PubMed1980

Breast cancer risk from low-dose exposures to ionizing radiation: results of parallel analysis of three exposed populations of women.

Breast cancer incidence data were analyzed from three populations of women exposed to ionizing radiation: survivors of the Hiroshima and Nagasaki atomic bombs, patients in Massachusetts tuberculosis sanitoria who were exposed to multiple chest fluoroscopies, and patients treated by X-rays for acute postpartum mastitis in Rochester, New York. Parallel analyses by radiation dose, age at exposure, and time after exposure suggested that risk of radiation-induced cancer increased approximately linearly with increasing dose and was heavily dependent on age at exposure; however, the risk was otherwise remarkably similar among the three population, at least for age 10-40 years at exposure, and followed the same temporal pattern of occurrence as did breast cancer incidence in nonexposed women of similar ages.

Adolescent↗
PubMed1979

Subunit structure of functional porin oligomers that form permeability channels in the other membrane of Escherichia coli.

Oligomers of a protein, porin, form permeability channels in the outer membrane of Escherichia coli B. A functional porin oligomer was identified and was purified to homogeneity by gel filtration in the presence of salts and sodium dodecyl sulfate. Molecular weights of purified porin oligomer and heat-dissociated monomer appeared to be 102,900 and 32,600, respectively, when determined by sedimentation equilibrium in the presence of sodium dodecyl sulfate. We concluded that the porin oligomer thus consists of three identical subunits. These data and results from other laboratories suggest porin trimers exist also in the outer membrane of intact cells, and participate in the formation of permeability channels. It was found that porin trimer bound less sodium dodecyl sulfate than the porin monomer.

Bacterial Proteins↗
PubMed1979

Characterization of porins from the outer membrane of Salmonella typhimurium. 1. Chemical analysis.

The three species of channel-forming outer membrane proteins, porins, have been purified to homogeneity from mutant strains of Salmonella typhimurium which produce single species of porin. Purification was by stepwise solubilization with dodecylsulfate or guanidine thiocyanate, gel filtration, and preparative gel electrophoresis. Amino acid compositions and tryptic peptide maps of the three species of porins showed close resemblance, but at the same time clear differences among them. The number of amino acid residues in the porins purified from the strains SH5551, SH6377 and SH6017 were 361, 354 and 345, and their calculated molecular weights 39800, 39300 and 38000, respectively. Amino-terminal and carboxyl-terminal amino acids in all three species of porins appeared to be alanine and phenylalanine, respectively. Neither half-cystine nor hexosamine was found in these preparation of porins. The isoelectric points of porins from the strains SH5551, SH6377 and SH6017, determined by isoelectric focusing, showed slight differences from each other. These results, and the genetic experiments from another laboratory, suggest that the three species of porins in Salmonella typhimurium are distinct polypeptides, probably coded for by distinct structural genes, which might have been derived from the same ancestral gene.

Amino Acids↗
PubMed1979

Characterization of porins from the outer membrane of Salmonella typhimurium. 2. Physical properties of the functional oligomeric aggregates.

We have purified to homogeneity, from mutant strains of Salmonella typhimurium, the small oligomers of porin that confer permeability channels to artificial vesicle membranes reconstituted from phospholipids and lipopolysaccharide. The molecular weights of the porin oligomers from the strains SH5551 and SH6017 appeared to be 130000 and 125000, respectively, and those of the monomers were 41000 and 37500, respectively, when determined by sedimentation equilibrium in the presence of dodecylsulfate. It was thus concluded that the functional porin oligomers consisted of three identical subunits. The Stokes' radius of the trimer . dodecylsulfate complex was around 5 nm. The trimer bound less dodecylsulfate than the monomer. The trimer . dodecylsulfate complex retained at room temperature the native conformation of porin, which is rich in beta-structure. When the trimers were dissociated further by various treatments, only the porin monomers were recovered in significant amounts, and the permeability-conferring activity was lost simultaneously. We propose, therefore, that the trimer is the minimal functional unit of porin that is capable of forming permeability channels in the outer membrane of Salmonella typhimurium.

Cell Membrane↗
PubMed1979

Cystic partially differentiated nephroblastoma and multilocular cyst of the kidney. Report of two cases of so-called multilocular cyst of the kidney.

Two cases of so-called multilocular cyst of the kidney are presented. Although both cases satisfied all of the criteria which characterize the multilocular cyst of the kidney, one had cystic lesions and neoplastic lesions (nephroblastoma-like lesions) and the other had only cystic lesions and was complicated with hamartoma. We prefer the term "cystic partially differentiated nephroblastoma" as the diagnostic term for the former and "multilocular cyst of the kidney" for the latter. A study of 40 reported cases of multilocular cystic lesions of the kidney revealed that cases having only cystic lesions were distributed in all ages from 4.5 months to 71 years and that cases having neoplastic lesions were seen in infants from 4 months to 2 years.

Adolescent↗
PubMed1979

Subcellular localization of the GABA-shunt enzymes in Euglena gracilis strain Z.

Glutamate decarboxylase, gamma-aminobutyrate-alpha-ketoglutarate aminotransferase and NAD-linked and NADP-linked succinic semialdehyde dehydrogenase, all constituting the GABA (gamma-aminobutyrate)-shunt pathway of glutamate metabolism are localized in the mitochondrial matrix in a streptomycin-bleached mutant of Euglena gracilis strain Z. Glutamate dehydrogenase, requiring NADP as the cofactor, was distributed in the cytoplasm. An improved version of the controlled digestion method for preparing Euglena mitochondria, which involves use of trypsin and a trypsin inhibitor and removal of broken cells before mechanical disruption of cells, is also described.

4-Aminobutyrate Transaminase↗
PubMed1979

Risk of breast cancer following low-dose radiation exposure.

Risk of breast cancer following radiation exposure was studied, based on surveys of tuberculosis patients who had multiple fluoroscopic examinations of the chest, mastitis patients given radiotherapy, and atomic bomb survivors. Analysis suggests that the risk is greatest for persons exposed as adolescents, although exposure at all ages carries some risk. The dose-response relationship was consistent with linearity in all studies. Direct evidence of radiation risk at doses under 0.5 Gy (50 rad) is apparent among A-bomb survivors. Fractionation does not appear to diminish risk, nor does time since exposure (even after 45 years of observation). The interval between exposure and the clinical appearance of radiogenic breast cancer may be mediated by hormonal or other age-related factors but is unrelated to dose. Age-specific absolute risk estimates for all studies are remarkably similar. The best estimate of risk among American women exposed after age 20 is 6.6 excess cancers/10(4) WY-G-Y (10(6) WY-rad).

Adolescent↗
PubMed1979

Glucose-containing oligosaccharides in normal human urine.

Normal human urine was treated with cetylpyridinium chloride (CPC), and the CPC-supernatant was passed through columns of Dowex 50 X 2 (H+ form) and Dowex 1 X 2(Cl-form) in succession. The concentrated effluent containing neutral saccharides was then gel-filtered through a column of Sephadex G-10. The resulting effluent was divided into 5 subfractions (SFs. 1-5). Comparison of hexose contents of the subfractions indicated that healthy individuals regularly excreted neutral oligosaccharides in urine with a similar pattern regardless of age or sex. Component A isolated from SF2 was characterized as glucosylgalactose by paper chromatography before and after acid hydrolysis of the intact one and its reduction product.

Adolescent↗
PubMed1979

Excretion of glucose-containing oligosaccharides in urines of orthopedic patients.

Urinary neutral oligosaccharides of various connective tissue diseases were studied by gel-filtration through Sephadex G--10 after treatments with cetylpyridinium chloride (CPC), Dowex 50 (H+ form) and Dowex 1 (Cl- form), in succession. Increased excretion of urinary glucose-containing oligosaccharides, specifically glucosylgalactose was observed in most of the patients with chondrosarcoma, rheumatoid arthritis, Werner's syndrome, Rothmund Thomson syndrome and Morquio's disease. However, urinary excretion of neutral oligosaccharides in the patients with osteosarcoma and other tumorous conditions, and some systemic disorders in the connective tissues, examined in the present study, showed almost normal values. It is indicated, therefore, that the activity of glucosidase in insufficient for the glucose-containing oligosaccharides produced from the ground substance(s) in the former type connective tissue diseases.

Adolescent↗
PubMed1979

Malignant breast tumors among atomic bomb survivors, Hiroshima and Nagasaki, 1950-74.

For 1950-74, 360 cases of malignant breast tumors were identified among the 63,000 females of the Radiation Effects Research Foundation's (Hiroshima and Nagasaki) Extended Life-Span Study sample of survivors of the 1945 atomic bombings of Hiroshima and Nagasaki; 288 of these females were residing in one of these two cities at the time of bombing (ATB). Two-thirds of all cases were classified as breast cancers on the basis of microscopic review of slides, and 108 cases received an estimated breast tissue dose of at least 10 rads. The number of cases of radiogenic breast cancer could be well estimated by a linear function of radiation dose for tissue doses below 200 rads. Excess risk estimates, based on this function, for women 10-19, 20-29, 30-39, and 50 years old or older ATB were 7.3, 4.2, 2.6, and 4.7 cases per million women per year per rad, respectively. Women irradiated in their forties showed no dose effect. Among all women who received at least 10 rads, those irradiated before age 20 years will have experienced the highest rates of breast cancer throughout their lifetimes. Separate excess risk estimates for Hiroshima and Nagasaki did not differ significantly, which indicates that for radiogenic breast cancer the effects of neutrons (emitted only in the Hiroshima explosion) and gamma radiation were about equal. Radiation did not reduce the latency period for the development of breast cancer, which was at least 10 years. The distribution of histologic types of cancers did not vary significantly with radiation dose. The data suggested that irradiation prior to menarche conferred a greater risk than irradiation after menarche.

Adolescent↗
PubMed1979

Breast cancer among atomic bomb survivors--the relationship of prognosis to pathologic findings.

Three hundred and sixty cases of breast cancer were collected from among the 63,000 female members of the Radiation Effect Research Foundation (RERF) extended Life Span Study sample which includes atomic bomb exposed women and controls of Hiroshima and Nagasaki. The relationship of these breast cancer cases to A-bomb radiation was sought, and in studying of 5-year survival, the following conclusions were obtained concerning its relationship to histopathological findings. The prognosis of the 50+ rad high dose group is the best, followed by the nonexposed group and the low dose group. The apparently better survival may be due to the fact that this group is heavily weighted in favor of those who were younger at the time of the bomb (ATB). There is no specificity of the histologic type of breast cancer in the survivors by dose. Nor is any significant difference observed in the distribution of tumor size and histological grade, though the survival rates of this series are worse than those of usual Japanese women with breast cancer. Cellular reaction is significantly marked in the stroma of carcinoma tissue in the high dose group. Immune reaction is considered to be strong in the affected site of breast cancer in the high dose group and this can be regarded as a finding suggestive of good prognosis. Further extended studies are therefore warranted.

Adult↗