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Biomedical subjects

K Nose

Publications and source records attributed to K Nose.

At least 127 records · Page 7Linked to original sources
PubMed1983

Distribution of nucleosomes on reconstituted chromatin from cloned mouse beta-globin DNA.

Relative abundance of nucleosomes on reconstituted chromatin was estimated with cloned mouse beta-globin gene DNA. Mononucleosomal DNA was isolated from reconstituted chromatin after digestion with micrococcal nuclease, nick-translated and used as a probe for blot hybridization. DNA fragments of restriction nuclease-digested globin DNA were transferred to DBM-paper and hybridized with mononucleosomal [32P] DNA probe. The results showed non-random distribution of nucleosomes.

Animals↗
PubMed1983

Detection of carcinogen-induced DNA breaks by nick translation in permeable cells.

A nick-translation reaction with E. coli DNA polymerase I (pol. I) was used to detect in situ DNA breaks produced by chemical carcinogens. Normal human fibroblasts treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in various doses were permeabilized with lysolecithin, and were nick translated in the presence of [3H]dCTP and pol. I. The radioactivity incorporated increased with MNNG concentration, and was directly proportional to the poly(ADP-ribose) synthetase activity. Other DNA-damaging agents such as bleomycin or 4-nitroquinoline 1-oxide also caused the nick translation rate to increase. When MNNG-treated cells were cultured in fresh medium containing no MNNG, the increase in the rate of nick translation in permeable cells became less and this decrease was abolished by addition of aphidicolin or cytosine arabinoside. The nick translation method described here may be a useful means for estimating intrinsic DNA breaks in cells treated with carcinogens.

4-Nitroquinoline-1-oxide↗
PubMed1982

A novel oxidative degradation of N-nitrosamine via electron transfer.

Anodic oxidation of N-nitrosamines derived from various secondary amines has been investigated by cyclic voltammetry and controlled-potential electrolysis at a glassy carbon electrode in acetonitrile. The nitrosamines give one, two, or three irreversible anodic peaks, depending upon the structure of the parent secondary amines. Electrolysis of simple dialkylnitrosamines gave the corresponding nitramines with coulometric n-values between 1 and 1.5, together with beta-ketonitrosamines in which the carbonyl group is on the same side as the nitroso-oxygen atom. With N-nitrosopiperidine (derived from a cyclic amine), N-nitropiperidine was formed in the same way, but the beta-oxidized nitrosamine was not detected in the solution from electrolysis. Added water (ca. 1%) in acetonitrile had essentially no effect on the electrochemistry of simple dialkylnitrosamines, whereas the first anodic peak of N-nitrosopiperidine was increased and the formation of N-nitropiperidine was inhibited in the macroscale electrolysis. In deoxygenated acetonitrile, the first anodic peaks of all the nitrosamines examined were enhanced and the other anodic peaks became obscure. Macroscale electroysis gave neither the nitramines nor the beta-ketonitrosamines and the coulometric n-value increased. It is suggested that unidentified oxidation processes produce electroactive species whose further oxidation results in various degradation products.

Nitrosamines↗
PubMed1981

Distribution of DNA-bound carcinogen 4-nitroquinoline 1-oxide and of repair-synthesized DNA in chromatin of WI-38 cells.

Distribution of DNA-bound 4-nitroquinoline 1-oxide (4NQO) and repair-synthesized DNA after treatment with 4NQO in chromatin was investigated with human diploid fibroblast WI-38. Cells were incubated with [3H] 4NQO, and sites of binding on chromatin DNA were analyzed either by sensitivity to micrococcal nuclease or DNase I, or by fractionation of chromatin on sucrose gradient centrifugation. The results showed that 4NQO preferentially binds to DNA of linker region of chromatin, but the binding was random with respect to transcriptional activity of chromatin. The distribution of repair-synthesized DNA in chromatin damaged by 4NQO was also studied by similar experiments. [3H] Thymidine incorporated into repaired DNA was more sensitive to nucleases, but distributed almost equally among DNAs of chromatin subfractions with different transcriptional activity.

4-Nitroquinoline-1-oxide↗
PubMed1981

Transcriptional activity of globin genes in uninducible variants of Friend leukemic cells.

Transcriptional activity of globin genes in inducible and uninducible Friend leukemic cells was studied by two different approaches in an attempt to identify the biochemical basis for the loss of inducibility. (1) Nuclei were isolated, and transcripts synthesized endogenously were purified by the Hg-UTP/sulfhydryl-Sepharose method. Globin mRNA sequences were quantitated by hybridization with [32P]globin cDNA. The results showed that the transcription of globin genes was stimulated in DMSO-treated inducible cell nuclei, whereas there was no activation of globin gene transcription in nuclei of uninducible variants cultured with DMSO. (2) Nuclei were prepared from inducible and uninducible Friend cells cultured in the presence or absence of DMSO, and were then subjected to limited digestion with DNase I. DNA was isolated from the nuclei after about 10% of total DNA had become acid-soluble, and was hybridized with globin cDNA. Globin genes either in inducible or in uninducible Friend cells were specifically susceptible to DNase I irrespective of the addition of inducer. From these studies, it was concluded that globin genes of uninducible Friend cells retained the "active conformation" but were not actively transcribed even in the presence of inducers.

Animals↗
PubMed1981

Transcription of globin genes in murine erythroleukemic cell chromatin by RNA polymerase II from mouse cells.

RNA polymerase II was purified from mouse Ehrlich ascites tumor cells, and was used to transcribe chromatin from Friend leukemic cells at various stages of induction. The transcription was entirely dependent on exogenous RNA polymerase, and was inhibited by actinomycin D, or a low dose of alpha-amanitin. Globin-specific sequences of the transcripts were determined by hybridization of 3H-labeled transcripts with plasmid DNA immobilized on filters. When chromatin from uninduced cells was used, less than 0.01% of the total radioactivity was retained on the globin DNA-filters, whereas about 0.05% was retained when chromatin was made from induced cells. This value was about one-ninth of the content of cytoplasmic globin mRNA which was pulse-labeled in induced cells. The transcription of whole chromatin or globin genes was inhibited almost completely by a rifampicin derivative, but in the case of chromatin, both sense and anti-sense strands of globin were transcribed. From these results, it is suggested that isolated chromatin retains some native conformation but is transcribed aberrantly.

Animals↗
PubMed1980

Quantitation of proinsulin mRNA sequences in hamster insulinoma cells in culture by molecular hybridization.

The content of proinsulin mRNA sequences was measured in a cultured cell line established from a transplantable hamster islet cell tumor, by hybridization with proinsulin cDNA. The cells cultured in vitro were found to contain a significant amount of proinsulin mRNA sequences, compared with non-insulin-producing hamster tissues, and seem to be a useful system for the study of insulin gene expression.

Adenoma, Islet Cell↗
PubMed1980

Transcriptional activity of nuclei from WI-38 cells at various passages.

Transcriptional activity of nuclei from human diploid fibroblast (WI-38) cells at different passage levels was studied with endogenous RNA polymerase. The rate and extent of the RNA synthesis decreased when the nuclei were prepared from senescent cells. The decreased activity of RNA synthesis in senescent cell nuclei was demonstrated from both the transcriptional assay and the estimation of the processing activity, i.e., polyadenylation of the transcripts.

Cell Division↗
PubMed1980

Specific inducibility of globin mRNA in Friend leukemia cells in low serum concentration.

Friend leukemia cells were adapted to grow in a medium containing 0.5% serum by gradually decreasing concentration of the serum from 15%. Upon treatment of the cells with dimethyl sulfoxide, appearance of benzidine-positive cells was suppressed in the cells cultivated in a 0.5% serum medium, whereas globin mRNA sequences, as determined by hybridization of cytoplasmic RNA with globin cDNA, increased to the same order as in the cells grown in a medium containing 15% serum. A small but significant amount of globin was synthesized in cells treated with dimethyl sulfoxide in 0.5% serum medium, as determined by dodecyl sulfate-polyacrylamide gel electrophoresis of 3H-labeled cellular proteins.

Animals↗
PubMed1976

Purification and characterization of alkaline phosphatase from rat kidney.

Alkaline phosphatase [EC 3.1.3.1.] was purified about 250-fold from rat kidney, and its enzymological properties were studied. Kidney homogenate was extracted with n-butanol, passed through Sephadex G-200 and chromatographed on a DEAE-cellulose column. The peak from the DEAE-cellulose column was subjected to isoelectric focusing, and the alkaline phosphatase activity was separated into two peaks. The molecular weights of alkaline phosphatase in these peaks were 4.8.X10(4) and 1.0X10(5), as determined by SDS-polyacrylamide gel electrophoresis. Anti-serum against alkaline phosphatase from rat kidney was prepared, and was shown to neutralize the activity from kidney, liver or bone, but not that from intestine.

Alkaline Phosphatase↗