PubMed Health⌕ Search

Biomedical subjects

Y Nishi

Publications and source records attributed to Y Nishi.

At least 19 recordsLinked to original sources
PubMed1979

Transplacental mutagenesis of products formed in the stomach of golden hamsters given sodium nitrite and morpholine.

Hamster embryos were exposed in utero to the action of sodium nitrite (NaNO2) and morpholine (Mo) administered simultaneously by stomach tube to the mothers on the 11th or 12th day of pregnancy. Embryo cells were examined for chromosomal aberrations, micronuclear formation, morphological or malignant transformation and drug resistance mutations. For detection of induced mutations, the embryo cells were cultured in normal medium for 72 h and then transferred to medium containing 10 or 20 micrograms/ml of 8-azaguanine (8AG) or 1m7 ouabain (Oua). The number of 8AG-, Ouaresistant colonies was markedly increased after administration of NaNO2 and Mo. The embryonic fibroblasts also showed a markedly increased frequency of micronucleation and a slight increase in chromosome aberrations. This treatment also caused morphological or malignant transformation of fetal cells. After cultivation in vitro, cells from some transformed colonies produced tumors when inoculated into the cheek pouch of young golden hamsters. Orally administered N-nitroso-morpholine (N-Mo), as a positive control, had the same transplacental biological actions on embryonic fibroblasts. However, transplacentally Mo alone was ineffective. A single administration of 500 mg/kg NaNO2 had only slight biological effects. N-Mo was produced in the stomachs of animals treated simultaneously with NaNO2 and Mo. A small amount of a nitrosamine, N-nitrosodimethylamine (DMN), was detected in the stomach after a single dose of NaNO2.

Animals↗
PubMed1979

Chromosomal aberrations induced by maleic hydrazide and related compounds in Chinese hamster cells in vitro.

The cytotoxic effects and chromosomal abnormalities induced by maleic hydrazide (MH) and its salts were investigated in cultured V79 cells. MH, and its potassium (K-MH) and diethanolamine (DEA-MH) salts were tested. MH was 5--14 times more cytotoxic than its salts and almost 4.5 times less toxic than the related compound, hydrazine dihydrochloride (HDC). MH salts had very weak cytotoxicity; the LD50 values on V79 cells on exposure for 3 h in vitro were (in microgram/ml) 1100 (MH), 12 000 (DEA-MH), 20 000 (K-MH), 230 (HDC) and 10 000 (NaCl). Both MH and its salts--but neither HDC nor NaCl--caused chromosomal aberrations in cultured V79 cells. The maximal frequencies of aberrant cells in cultures exposed to the compounds for 3 h in vitro were 18% (mh at 100 microgram/ml), 18% (K-MH at 20 000 microgram/ml) and 13% (DEA-MH at 20 000 microgram/ml). Maximal frequencies observed in cultures treated with HDC or NaCl were 10% (HDC at 400 microgram/ml) and 5% NaCl at 10 000 microgram/ml). Those of positive groups were 97% (N-methyl-N'-nitro-N-nitrosoguanidine, MNNG, at 5 microgram/ml) and 16% (ethyl methanesulfonate, EMS, at 400 microgram/ml). These frequencies of MH and its salts were 3.25--4.5 times those in untreated control cells. These results suggested that MH and its salts had weak inducibili

Animals↗
PubMed1979

Transplacental action of sodium nitrite on embryonic cells of Syrian golden hamster.

Hamster embryos were treated with various doses of NaNO2 in utero, by its oral administration to the mothers, and then the embryonic cells were examined for micronucleus formation, chromosomal aberrations, morphological or malignant transformation and drug-resistant mutations. For induction of resistant mutations, the cells were cultured in normal medium for 72 h, and then selected in media containing 8-azaguanine (10 or 20 microgram/ml) or 1 mM ouabain. This treatment with NaNO2 caused marked dose-dependent induction of 8-azaguanine- and ouabain-resistant mutations. Cultured embryonic fibroblasts in the resting state also showed a marked dose-dependent increase in micronucleus formation but not an increase in chromosomal aberrations. This treatment also caused morphological and neoplastic transformation of the cells. Transplacental oral treatment with DMN, as a positive control, caused changes of similar extent in biological effects of embryonic fibroblasts, and in addition it caused chromosomal aberrations in metaphase plates. On the contrary, transplacental oral application of NaNO2 did not induce any biological change in cultured embryonic fibroblasts.

Abnormalities, Drug-Induced↗
PubMed1978

Topographical studies on intestinal microvillous leucine beta-naphthylamidase on the outer membrane surface.

The location of leucine beta-naphthylamidase on the outer surface of the microvillous membrane of rabbit small intestine was examined by analyzing the interaction of antibodies against leucine beta-naphthylamidase or another microvillous enzyme, sucrase-isomaltase complex, with microvillous vesicles having different relative amounts of these enzymes, in respect to vesicle agglutination, inhibition of enzyme activity, and electron-microscopic morphology. The results obtained indicate that leucine beta-naphthylamidase, or at least its antigenic sites, protrude about 10 nm from the outer surface of the microvillous membrane.

Animals↗
PubMed1978

Mutagenic effect of orally given AF-2 on embryonic cells in pregnant Syrian hamsters.

Pregnant hamsters were given various doses of AF-2 by stomach tube; then the cells of their embryos were isolated and cultured in normal medium. Chromosome preparations were made within 24 h after the start of primary culture, and examined for chromosomal aberrations. Marked chromosomal abnormalities were observed in cells of embryos of animals treated with AF-2 at over 20 mg/kg. Samples of surviving cells were also cultured in normal medium for 48 h, and then selected in medium containing 8AG or 6TG. This treatment with AF-2 caused marked dose-dependent induction of 8AG- or 6TG-resistant mutations: mutant colonies were even obtained after a single treatment with 2 mg of AF-2 per kg. These results show that this is a sensitive and useful mammalian system for detecting environmental mutagens.

Administration, Oral↗
PubMed1978

Chromosome breakage and neoplastic transformation of Syrian golden hamster embryonic cells in tissue culture by transplacental application of 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2).

Hamster embryos were treated with 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) in vivo (in the mother) by transplacental application. The fetuses were isolated 24 h after administration of the AF-2 and cultured. Within the first 24h of primary culture, some parts of the cells were treated with colcemide for 3 h so that mitotic cells could be observed in the first cell cycle in vitro. Cultured embryonic fibroblasts in metaphase plates showed a marked dose-dependence in chromosomal aberrations. Transplacental application of AF-2 also caused slightly dose-dependent morphological transformation. When some transformed colonies were cloned and transferred to the hamster cheek pouch, these cells produced tumors in the host animals. This new in vivo--in vitro combination assay system is considered to be useful for detection of environmental potential carcinogens.

Animals↗
PubMed1978

Localization of intestinal sucrase-isomaltase complex on the microvillous membrane by electron microscopy using nonlabeled antibodies.

Microvillous vesicles isolated from rabbit small intestine showed a trilaminar membrane with a rather smooth surface, which was apparently not affected by papain solubilizing sucrase-isomaltase complex or by trypsin unable to solubilize it. When microvilous vesicles or trysinized ones were incubated with immunoglobulin G against the sucrase-isomaltase complex or monovalent fragments therefrom, an apparently continuous electron-opaque layer approximately 180 A in width appeared around the external surface of vesicles. Such a layer was not formed on papainized vesicles. Microvillous vesicles and trypsinized ones negatively stained with phosphotungate showed a great number of particles protruding approximately 150 A from the membrane surface, but papainized vesicles did not. The particles existed close to one another and appeared to form a particulate layer 150 A in width on the surface. The antibodies, whether they were divalent or monovalent, increased the width of the layer to approximately 200 A and obscured the fine particulate structure of intact and trypsinized vesicles. Papainized vesicles retained their smooth surface upon interaction with antibodies. These results, together with those with the Triton-solubilized sucrase- isomaltase complex (Nishi and Takesue, 1978), J. Ultra-struct. Res., 62:1- 12), indicate not only that sucrase-isomaltase complexes are located close to one another on the membrane, but also that they or at least their protein portions protrude approximately 150 A from the surface of the trilaminar membrane.

Antigen-Antibody Reactions↗
PubMed1977

Neoplastic transformation induced by furylfuramide and nitromethylfuran of embryonic hamster cells in tissue culture.

Secondary cultures of Syrian hamster embryonic fibroblasts were tested for transformation and neoplastic properties after exposure in vitro to furylfuramine (AF-2) and other nitrofurans. Typical morphological transformation was seen in five of six cultures between 30 and 186 days following treatment with 5-10X10(6) M AF-2 for 24 h. Transformation was seen in only one of four cultures 145 days after treatment for 6 h with AF-2. Treatment with 5-10X10(6) M NMF (5-nitro-2-methylfuran) for 24 h also induced transformation after 50 and 118 days in two cultures. In contrast, untreated cultures and cultures treated with 5-10X10(-6) M NFT [4-(5-nitro-2-furyl)thiazole] for 24 h were not transformed within 200 days. Three of the six lines transformed by AF-2 and both lines transformed by NMF also became tumorigenic 7-24 days after morphologic transformation. The other three transformed lines produced nodules which regressed within a few weeks of transplantation. Untreated and treated non-transformed lines did not produce tumors during an observation period of 6 months. The tumors were classified as fibrosarcomas. The ability to form colonies in soft agar was acquired by only one tumorigenic line.

Animals↗
PubMed1977

Immunochemical studies on the subunits of rabbit-intestinal sucrase-isomaltase complex.

Purified sucrase-isomaltase complex sucrose alpha-glucohydrolase, EC 3.2.1.48 - dextrin 6-alpha-glycanohydrolase, EC 3.2.1.10) solubilized by papain from rabbit intestine was dissociated by citraconylation into its subunits, sucrase and isomaltase, which were then isolated in a form active immunologically as well as enzymatically by affinity chromatography on Sephadex G-200 and gel-filtration on Bio-gel P-300. Antibodies against the purified complex inhibited isomaltase but not sucrase and formed precipitation lines, crossing each other, with isolated sucrase and isomaltase, showing that the two enzymes differ in antigenicity from each other. By absorbing the antibodies with isolated sucrase and isomaltase, antibodies specific for isomaltase and sucrase, respectively, were obtained. Like the original antibodies, both of the specific antibodies quantitatively agglutinated microvillous vesicles. Sucrase was inhibited by neither of the antibodies. In contrast, isomaltase was greatly inhibited by the isomaltase-specific antibodies, but not by the sucrase-specific ones.

Agglutination↗
PubMed1977

Effective temperature scale useful for hypo- and hyperbaric environments.

Basic physics of man's heat exchange by radiation, convection, evaporation, and conduction through clothing is used to define and establish a Standard Effective Temperature Scale (SET), with which sensory and physiological responses of sedentary and active personnel can be related. The standard environment chosen is the Effective Temperature (ET) Scale, used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers; namely, as the temperature of an isothermal enclosure at sea level with 50% rh and still air (0.1-0.15 m/s) in which a clothed (0.6 clo) sedentary subject would exchange the same total sensible and insensible heat as in the actual test environment. Mean skin temperature (Tsk) and skin wettedness (w) can be associated at sea level with thermal comfort and neutrality and with heat exchange. For hypo- and hyperbaric environments, thermal equivalence between SET and any test environment occurs when mean body temperature (Tb) for each is identical. Comprehensive data, developed for a 2-node model of human temperature regulation and of the associated partitional calorimetry, demonstrates the expected interaction between SET and the basic environmental and clothing factors over the barometric range 0.33 to 30 ATA.

Air Movements↗
PubMed1976

Mutagenic effects of AF-2, a food additive, on embryonic cells of the Syrian golden hamster on transplacental application.

Hamster embryos were treated with AF-2 in vivo (in the mother) by transplacental application. Their cells were then isolated, cultured in normal medium for 48 h, and then selected in media containing various concentrations of 8AG or 6TG. This treatment with AF-2 caused marked dose-dependent induction of 8AG- or 6TG-resistant mutants. Direct administration of AF-2 and MNNG to embryonic hamster cells also produced 8AG- and 6TG-resistant colonies. This new method is concluded to be very useful for detection of environmental mutagens and carcinogens when combined with the in vivo-in vitro combination assay of chemical carcinogenesis (transformation test).

Acrylamides↗