Biomedical subjects

S Nishimura

Publications and source records attributed to S Nishimura.

At least 703 records · Page 39Linked to original sources

PubMed1986

Nucleotide sequence of the Escherichia coli dnaJ gene and purification of the gene product.

The dnaJ and dnaK genes are essential for replication of Escherichia coli DNA, and they constitute an operon, dnaJ being downstream from dnaK. The amount of the dnaJ protein in E. coli is substantially less than that of the dnaK protein, which is produced abundantly. In order to construct a system that over-produces the dnaJ protein, we started our study by determining the DNA sequence of the entire dnaJ gene, and an operon fusion was constructed by inserting the gene downstream of the lambda PL promoter of an expression vector plasmid, pPL-lambda. Cells containing the recombinant plasmid produced dnaJ protein amounting to 2% of the total cellular protein when cells were induced. The overproduced protein was purified, and Edman degradation of the protein indicated that the NH2-terminal methionine was found to be processed. From the DNA sequence of the dnaJ gene, the processed gene product is composed of 375 amino acid residues, and its molecular weight is calculated to be 40,975.

Amino Acid Sequence↗

PubMed1986

Bioactive chitin derivatives. Activation of mouse-peritoneal macrophages by O-(carboxymethyl)chitins.

The effect of O-(carboxymethyl)chitins (CM-chitins) on the activation of mouse-peritoneal macrophages in vivo and their mitogenic activity on mouse spleen-cells were investigated. The induction of cytotoxic macrophages is enhanced by an increase of negative charge at O-6 and decreased by further modification at O-3 of the GlcNAc residue. CM-Chitins had a minor effect on mitogenic activity that was independent of the site of modification; partially N-deacetylated chitins had little activity. Although there was remarkable enhancement of accessibility to lysozyme upon modification at O-6 of the GlcNAc residue, the accessibility was decreased by further substitution at O-3.

Animals↗

PubMed1986

Nucleotide sequence of the coding region of the mouse N-myc gene.

A genomic clone for the mouse N-myc gene was isolated and the total nucleotide sequence (4807 bp) of the two coding exons and an intron located between them was determined. The amino acid sequence of the N-myc protein was deduced from the DNA sequence. This protein is composed of 462 amino acids, slightly larger than human and mouse c-myc proteins, and is rich in proline like the c-myc protein. Comparison of the amino acid sequences of the mouse N-myc and c-myc proteins showed that conserved sequences are located in eight regions: four regions are in the N-terminal half of the N-myc protein and are separated from each other by regions poorly homologous to those of the c-myc protein, and the four others are located in the C-terminal half, throughout which certain homology exists. A remarkable sequence containing 13 successive acidic amino acids is present in one of the conserved regions located in the middle of the N-myc protein.

Animals↗

PubMed1986

Dramatic events in ciliate evolution: alteration of UAA and UAG termination codons to glutamine codons due to anticodon mutations in two Tetrahymena tRNAs.

The three major glutamine tRNAs of Tetrahymena thermophila were isolated and their nucleotide sequences determined by post-labeling techniques. Two of these tRNAs show unusual codon recognition: a previously isolated tRNA(UmUA) and a second species with CUA in the anticodon (tRNA(CUA)). These two tRNAs recognize two of the three termination codons on natural mRNAs in a reticulocyte system. tRNA(UmUA) reads the UAA codon of alpha-globin mRNA and the UAG codon of tobacco mosaic virus (TMV) RNA, whereas tRNA(CUA) recognizes only UAG. This indicates that Tetrahymena uses UAA and UAG as glutamine codons and that UGA may be the only functional termination codon. A notable feature of these two tRNAs is their unusually strong readthrough efficiency, e.g. purified tRNA(CUA) achieves complete readthrough over the UAG stop codon of TMV RNA. The third major tRNA of Tetrahymena has a UmUG anticodon and presumably reads the two normal glutamine codons CAA and CAG. The sequence homology between tRNA(UmUG) and tRNA(UmUA) is 81%, whereas that between tRNA(CUA) and tRNA(UmUA) is 95%, indicating that the two unusual tRNAs evolved from the normal tRNA early in ciliate evolution. Possible events leading to an altered genetic code in ciliates are discussed.

Journal Article↗

PubMed1986

Nucleotide sequence of the BamHI repetitive sequence, including the HindIII fundamental unit, as a possible mobile element from the Japanese monkey Macaca fuscata.

Clustered repeat units produced by BamHI digestion of genomic DNA from the Japanese monkey Macaca fuscata [JMr(BamHI)] were sequenced by dideoxy DNA sequencing. The nucleotide sequences of several individual repeats showed that the BamHI repeat contains the 170-bp HindIII element as an integral part, and that it has more than 90% homology with the HindIII repeat element [AGMr(HindIII)] found in the genomic DNA of the African green monkey. In the JMr(BamHI) repeat unit, the 170-bp HindIII element is flanked by a 6-bp inverted repeat, which is part of a 22-bp direct repeat. This latter repeat of 22-bp asymmetrically overlaps the border between the internal AGMr(HindIII)-like region and adjacent regions of the JMr(BamHI) repeat. A similar structural feature of the BamHI repeat unit has been found in the genomic DNA of the baboon, but not in that of the African green monkey. These results show clearly that the BamHI repeat of the modern Japanese monkey originated as a result of insertion of an AGMr(HindIII) element into a certain site(s) of the genomic DNA of an ancestor of the modern Japanese monkey before Macaca-Cercocebus divergence.

Animals↗

PubMed1986

Direct surgical treatment of intracavernous internal carotid artery aneurysms: report of four cases.

The authors have operated directly on four cases of intracavernous internal carotid artery aneurysms by opening the cavernous sinus. Surgery was performed using a semisitting position, in which the upper half of the patient's body was elevated approximately 20 degrees from the horizontal plane. The superior wall of the cavernous sinus was opened through the pterional approach, and an aneurysmal neck clipping was successfully performed on three patients. A coating of the aneurysm was carried out on one patient. The results obtained were excellent in all cases. The authors believe that the operative technique reported is useful for surgical treatment of intracavernous lesions.

Adult↗

PubMed1986

The orbitozygomatic infratemporal approach: a new surgical technique.

Lesions in the parasellar region and the interpeduncular fossa, including medial-third sphenoid wing meningiomas, petroclival meningiomas, trigeminal neurinomas, and basilar tip aneurysms, are very difficult to approach for radical procedures. To minimize brain retraction and achieve excellent exposure in the shortest possible distance for safe manipulation within these regions, the authors have developed a new surgical technique, an orbitozygomatic infratemporal approach. Sixteen patients with parasellar tumors, nine patients with basilar tip aneurysms, and one patient with a P-1 distal aneurysm were operated on using this orbitozygomatic infratemporal approach, with excellent results. The operative technique and its results are detailed.

Adult↗

PubMed1986

The protective effects of vitamin E on microcephaly in rats X-irradiated in utero: DNA, lipid peroxide and confronting cisternae.

Fetuses from rats given either water or 0.03% D,L-alpha-tocopherol acetate (vitamin E) as a drinking fluid and X-irradiated with 100 rad on gestational day 13 were examined on gestational day 21. Mean cerebral weight which was significantly reduced by the X-irradiation was increased by vitamin E supplementation but the level did not reach that in sham-irradiated controls. Administration of vitamin E caused an increase in DNA concentration which was significantly reduced by X-irradiation with water treatment. An increase in the mean level of lipid peroxide formation was observed in the water-treated, X-irradiated group in the sample at zero time but not in the vitamin E-treated, X-irradiated group. In the cytoplasm of fetal cerebral neurons from X-irradiated dams with vitamin E supplementation, confronting cisternae were frequently observed between two nuclear envelopes. Confronting cisternae may be considered as a repair mechanism of vitamin E against X-irradiated neuronal damage in the fetal cerebrum. This study provides evidence of the protection by vitamin E of neuronal development in X-irradiated fetuses, through its antioxidant properties, against attacks by free radicals and/or lipid peroxide.

Abnormalities, Radiation-Induced↗

PubMed1986

Stable isotope dilution quantification of mutagens in cooked foods by combined liquid chromatography-thermospray mass spectrometry.

A method of general applicability for the detection and quantification of mutagens in cooked foods at the ppb level is presented. A minimal sample prefractionation is employed and [Me-2H3]-labeled analogs of the compounds of interest are added for identification and quantification of mutagens by accurate measurement of chromatographic retention (K') in reverse-phase high-performance liquid chromatography (HPLC), and by measurement of the ratio of response of the protonated molecular ions of analyte and internal standard by directly coupled liquid chromatography-mass spectrometry (LC/MS). Initial application is demonstrated in the analysis of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) in broiled salmon. Measured levels of IQ and MeIQ in broiled salmon flesh were 0.3-1.8 ppb and 0.6-2.8 ppb, respectively, and for the skin of broiled salmon 1.1-1.7 ppb and 1.5-3.1 ppb, respectively. Results on cooked beef and sardine are also reported.

Animals↗

PubMed1986

Short latency SEPs in infants and children: developmental changes and maturational index of SEPs.

Short latency SEPs were studied in 56 normal subjects, aged 1 month to 34 years. To identify wave components definitely, simultaneous recordings not only with bipolar leads but also with superimposing methods (comparing the recordings with postcentral- and frontal-non-cephalic references (NC), contralateral to the stimulation side) were obtained in addition to routine recordings with postcentral-NC leads. Four positive (P1, P2, P3 and P4) and 2 negative (N' and N1) peak components were usually identified in all age groups, which represented the developmental changes in their features. By the method of serial representation of SEPs at each age, P1, P2, P3, P4, N' and N1 in children were found to correspond to P9, P11, P13, P14, N18 and N20 in adults, respectively. The features of SEPs in children showed great maturational changes until adolescence when they showed adult patterns. The values of the latencies of P1 and P2 divided by body height, which may be regarded as a maturational index mainly in the peripheral part of the sensory pathway, decreased with age, reaching the adult range at 3-4 years of age. The value of the N1-P3 interpeak latency divided by head circumference, which may be regarded as a maturational index mainly in the central part of the sensory pathway, also decreased with age, reaching the adult range at school age. These indices may be useful in practice for developmental evaluation of the nervous system in children.

Adolescent↗

PubMed1986

The protective effects of vitamin E against microcephaly in rats X-irradiated in utero: dendritic branches.

Fetuses from rats given either water or 0.03% dl-alpha-tocopherol acetate (vitamin E) as the drinking fluid and X-irradiated with 100R on gestational day (gd) 13 were examined on gd 21. The degree of dendritic branching of frontal cerebral neurons, examined after Golgi staining, was significantly reduced by X-irradiation, and supplementation of vitamin E caused increased branching order numbers in irradiated fetuses. This study provides evidence of the protection by vitamin E of neuronal development in X-irradiated fetuses.

Abnormalities, Radiation-Induced↗

PubMed1986

Developmental change of short latency somatosensory evoked potential waves between P3 and N1 components in children.

We attempted to isolate and identify the negative waves between the conventional P3 and N1 components of short latency somatosensory evoked potentials (S-SEPs) in children. Twenty normal children ranging in age from 3 months to 12 years, and 11 adolescents and adults were studied. The median nerve was stimulated and recordings from F (F3 or F4) and C' (1-2 cm posterior to C3 or C4) contralateral to the stimulation site were simultaneously obtained in order to identify each negative wave in the C' recording. The wave of C' coincident with that of F was regarded as the far-field potential, and the wave of C' that diverged from F as the near-field potential at the scalp. There were one negative wave (N1) in the far-field potential and 2 negative waves (N2 and N1(3)) in the near-field potential, after the P3 component. "N1(3)" was conventional N1 and "N2" was the negative wave just before N1(3). In infants and younger children, the interpeak latencies of P3-N1(3) and P3-N2 were markedly elongated in comparison with that in older children. These interpeak latencies may be useful as an index of cerebral maturation.

Child↗

PubMed1986

Queuine analogues. Their synthesis and inhibition of growth of mouse L5178Y cells in vitro.

A variety of analogues of queuine (7-[(3S,4R,5S)-4,5-dihydroxycyclopent-1-en-3-ylaminomethyl]- 7 -deazaguanine), i.e., those with 7-N-substituted aminomethyl side chains and those in which the oxygen function at the 6 position of the 7-deazaguanine ring was replaced by sulfur, were synthesized and tested for ability to act as substrates for tRNA-guanine transglycosylase and for inhibitory effects on growth of mouse L5178Y leukemic cells in vitro. Of the compounds tested, analogues with sulfur at the 6 position of the 7-deazaguanine ring in place of oxygen or with an N-o-hydroxyphenyl, N-m-hydroxyphenyl, or iodoacetyl group in the 7-aminomethyl side chain in place of the naturally occurring cyclopentene diol moiety markedly inhibited the growth of cells at concentrations of 1-10 micrograms/mL, although queuine itself had practically no effect at a concentration of 100 micrograms/mL.

Animals↗

PubMed1986

Formation of 8-hydroxyguanine moiety in cellular DNA by agents producing oxygen radicals and evidence for its repair.

8-Hydroxydeoxyguanosine (8-OH-dG) was detected in DNA isolated from HeLa cells after the cells in tissue culture had been irradiated with X-rays and from the liver of mice after the whole animals had been irradiated with gamma-rays. The amounts of 8-OH-dG in DNA after in vivo irradiation were three orders of magnitude lower than those after in vitro irradiation (0.008-0.032 8-OH-dG residue/10(5) dG/krad). The 8-OH-dG produced in liver DNA by irradiation of mice decreased with time, suggesting the presence of a repair enzyme(s) acting on 8-OH-dG in mouse liver. Treatment of Salmonella typhimurium cells with hydrogen peroxide also caused increase in the 8-OH-dG content. These results indicate that 8-OH-dG is formed in vivo in cellular DNA on treatment with various oxygen radical-producing agents and that it is repairable.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1986

Diabetes due to secretion of a structurally abnormal insulin (insulin Wakayama). Clinical and functional characteristics of [LeuA3] insulin.

We have identified a non-insulin-dependent diabetic patient with fasting hyperinsulinemia (90 microU/ml), an elevated insulin:C-peptide molar ratio (1.68; normal, 0.05-0.20), normal insulin counterregulatory hormone levels, and an adequate response to exogenously administered insulin. Insulin-binding antibodies were absent from serum, erythrocyte insulin receptor binding was normal, and greater than 90% of circulating immunoreactive insulin coeluted with 125I-labeled insulin on gel filtration. The patient's insulin diluted in parallel with a human standard in the insulin radioimmunoassay, confirming close molecular similarity. The patient's insulin was purified from serum and shown to possess both reduced binding and ability to stimulate glucose uptake and oxidation in vitro. Analysis of the patient's insulin by high-performance liquid chromatography (HPLC) revealed two products: 7.3% of insulin immunoreactivity coeluted with the human standard, while the remaining 92.7% eluted as a single peak with increased hydrophobicity. Family studies confirmed the presence of hyperinsulinemia in four of five relatives in three generations, with secretion of an abnormal insulin documented by HPLC in the three tested. Leukocyte DNA was harvested from the propositus and the insulin gene cloned. One allele was normal, but the other displayed a thymine for guanine substitution at nucleotide position 1298 from the putative cap site, resulting in a leucine for valine substitution at position 3 of the insulin A chain. Insulin Wakayama is therefore identified as [LeuA3] insulin.

Adipose Tissue↗

PubMed1986

Chemistry of mutagens and carcinogens in broiled food.

From a chemical point of view, the following subjects are important areas in studies on mutagens and carcinogens in broiled foods. In addition to heterocyclic amines which need microsomal activation, the structural elucidation of more labile direct-acting mutagens is necessary. It is known that there are still various unknown minor mutagens in broiled foods. Although the structural characterization of such compounds is more difficult, it is important since they might be hazardous in spite of their low mutagenicity. A more feasible and easier method for quantitative analysis of mutagens, in addition to HPLC and GC/MS methods presently employed, must be developed. The mechanism of formation of mutagens by broiling of food should be studied. An effective chemical method to prevent formation of mutagens or to destroy them, once formed, should be developed.

Carcinogens↗

PubMed1986

Hydroxylation of guanine in nucleosides and DNA at the C-8 position by heated glucose and oxygen radical-forming agents.

Heated glucose is mutagenic to Salmonella typhimurium TA 100 in the absence of S-9 mix. For identifying unknown mutagens in heated glucose (dry solid, 200 degrees C, 20 min), reaction with isopropylideneguanosine (IPG) was followed by isolation and characterization of the mutagen-IPG adduct. Two adducts, glyoxal-IPG and 8-hydroxy-IPG, were identified in the reaction mixture by this technique. To elucidate the mechanism of this hydroxylation reaction, we investigated the abilities of various agents to hydroxylate deoxyguanosine or guanine base in DNA. Various reducing agents, metals, asbestoses, polyphenols, aminophenols, and X-ray were effective for hydroxylation, and an oxygen radical seems to be the reactive species. For sensitive detection of 8-hydroxyguanine, a monoclonal antibody for it was prepared.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1986

Analysis of mutagens from cooked foods by directly combined liquid chromatography-mass spectrometry.

Directly combined high performance liquid chromatography-mass spectrometry (LC/MS) has been studied as a method of analysis of heterocyclic aromatic mutagens in cooked foods, in the parts per billion concentration range. Identification and semiquantitative estimation of mutagens is based on accurate measurement of chromatographic retention (k') and molecular weight-selective detection of mutagens, which are protonated during passage of the chromatographic eluant into a thermospray interface of a quadrupole mass spectrometer. Standard chromatographic retention (k') values in two reversed-phase systems and data from thermospray mass spectra from nine mutagens are reported. An isolation scheme employing CH3OH extraction, acid-base partition, cellulose-trisulfo-Cu-phthalocyanine adsorption, and normal-phase HPLC was used prior to LC/MS analysis. Initial applications have been demonstrated in the analysis of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) in broiled salmon flesh. Levels measured were estimated to be in the range 0.2 to 0.4 microgram/kg IQ and 0.4 to 0.9 microgram/kg MeIQ. The method is judged to be generally applicable with minimal sample prefractionation to detection of mutagens at the parts per billion level in cooked foods.

Animals↗