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Biomedical subjects

A Murakami

Publications and source records attributed to A Murakami.

At least 55 records · Page 3Linked to original sources

Study on structure of ribosomal RNA by time-resolved luminescence anisotropy analysis.

Evaluation of the folded structure of E.coli 16S-rRNA was performed using 5'-Ru(II) complex labeled oligodeoxyribonucleotide (Ru-probe) as the probe. This probe could evaluate the dynamic manner of the binding site of Ru-probe by using the time-resolved luminescence anisotropy technique. It was found that the rotational manner of Ru-probe in the presence of 16S-rRNA was markedly dependent on the oligonucleotide sequence, indicating that the microenvironments around the Ru-probes were largely different.

Anisotropy↗

Structure/function relationship in the polyplexes containing cationic polypeptides for gene delivery.

Various cationic polypeptides of linear or highly branched structures were synthesized by introducing tertiary or quaternary ammonium groups and hydroxyl groups to poly(L-lysine) (PL) or polyamideamine (PAMAM) dendrimers. These polycations were mixed with plasmid DNA to form polyplexes and subjected to in vitro gene introduction experiment. The transient gene expression was greatly affected by the side groups of PL derivatives or the surface cation charge density of PAMAM dendrimers. This difference in gene expression was found to result from two independent factors as follows: one is the cellular uptake of the polyplexes and the other is the compaction of the polyplexes. Lower charge density of PAMAM dendrimers suppressed the polyplex formation and cellular uptake, resulting the lower gene expression. Only the polycations that form polyplexes compacted at an adequate extent lead an effective gene expression, suggesting that the physicochemical properties of the polyplexes defined by the chemical structures of the polycations play an important role in the effective gene transfer.

Amino Acid Sequence↗

Cluster analysis of human and animal pathogenic Microsporum species and their teleomorphic states, Arthroderma species, based on the DNA sequences of nuclear ribosomal internal transcribed spacer 1.

We performed a cluster analysis of human and animal pathogenic Microsporum species and their teleomorphic states, Arthroderma species, including A. otae-related species (M. canis, M. audouinii, M. distortum, M. equinum, M. langeronii, and M. ferrugineum) and M. gypseum complex (A. fulvum, A. gypseum, and A. incurvatum) using DNA sequences of nuclear ribosomal internal transcribed spacer 1 (ITS1). The dendrogram showed the members of A. otae-related species to be monophyletic and to construct an extremely closely related cluster with a long horizontal branch. This ITS1-homologous group of A. otae was organized in 6 unique genotypes, while sequences of the members of the ITS1-homologous group of M. gypseum complex are more diverse. This ITS1-based database of Microsporum species and their teleomorphic states will provide a useful and reliable species identification system: it is time-saving (takes two to three days), accurate and applicable even to strains with atypical morphological features or in a non-culturable state.

Animals↗

In vitro absorption and metabolism of nobiletin, a chemopreventive polymethoxyflavonoid in citrus fruits.

The polymethoxyflavonoid (PMF), nobiletin (NOB), specifically occurs in citrus fruits, and is currently believed to be a promising anti-inflammatory and antitumor promoting agent. In the present study, we investigated the in vitro absorption and metabolism of NOB and compared them with those of the polyhydroxyflavonoid (PHF), luteolin (LT). NOB preferentially accumulated in a differentiated Caco-2 cell monolayer, which is a model for small intestinal epithelial cells, while LT did not. Treatment of NOB with a rat liver S-9 mixture led to the formation of 3'-demethyl-NOB, while that of LT did not. We thus suggest that PMFs including NOB have properties distinct from those of general flavonoids for absorption and metabolism in vitro.

Animals↗

Anti-tumor promoting activity of bufadienolides from Kalanchoe pinnata and K. daigremontiana x tubiflora.

Five bufadienolides (1-5) isolated from the leaves of Kalanchoe pinnata and K. daigremontiana x tubiflora (Crassulaceae) were examined for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation in Raji cells induced by the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate. All bufadienolides showed inhibitory activity, and bryophyllin A (1) exhibited the most marked inhibition (IC50 = 0.4 microM) among the tested compounds. Bryophyllin C (2), a reduction analogue of 1, and bersaldegenin-3-acetate (3) lacking the orthoacetate moiety were less active. These results strongly suggest that bufadienolides are potential cancer chemopreventive agents.

Animals↗

Light irradiation induces fragmentation of the plasmodium, a novel photomorphogenesis in the true slime mold Physarum polycephalum: action spectra and evidence for involvement of the phytochrome.

A new photomorphogenesis was found in the plasmodium of the true slime mold Physarum polycephalum: the plasmodium broke temporarily into equal-sized spherical pieces, each containing about eight nuclei, about 5 h after irradiation with light. Action spectroscopic study showed that UVA, blue and far-red lights were effective, while red light inhibited the far-red-induced fragmentation. Difference absorption spectra of both the living plasmodium and the plasmodial homogenate after alternate irradiation with far-red and red light gave two extremes at 750 and 680 nm, which agreed with those for the induction and inhibition of the fragmentation, respectively. A kinetic model similar to that of phytochrome action explained quantitatively the fluence rate-response curves of the fragmentation. Our results indicate that one of the photoreceptors for the plasmodial fragmentation is a phytochrome.

Animals↗

[Specific and rapid identification of Malassezia species based on the DNA sequences of nuclear ribosomal internal transcribed spacer 1 regions].

Species identification of genus Malassezia is important in epidemiological and etiological studies, however, is difficult by the conventional system. A specific and rapid identification system based on sequences of internal transcribed spacer 1 of ribosomal DNA has therefore been developed. Using this system, we could identify two or more species mixed in the clinical samples.

Animals↗

Experimental study of small arterial anastomosis with gelatin-resorcin-formaldehyde glue and collagen sheet.

In cardiovascular surgery, the manual continuous suture has often been used for microvascular anastomosis, but the luminal irregularity often causes thrombotic stenosis in the anastomosis sites. The purpose of this study was to examine the feasibility of the combined use of gelatin-resorcin-formaldehyde (GRF) glue and a collagen sheet for the anastomosis of small arteries 3 to 4 mm in diameter in experimental animals. End-to-end anastomoses of the carotid and femoral arteries of mongrel dogs were carried out with the combined use of GRF glue and collagen sheet. The physical strength of the anastomosis, the histopathologic condition of the vassels, and the absorptivity and the inflammatory response of the glue were evaluated. The physical strength of the anastomosis sites was good and their flexibility optimal, the smooth luminal surface appeared excellent for preventing thrombotic stenosis in all follow-up periods, and the glue was absorbed almost completely within 12 weeks postoperatively. The combined use of GRF glue and collagen sheet would be feasible for the anastomosis of small arteries 3 to 4 mm in diameter and could substitute for the conventional suture method.

Anastomosis, Surgical↗

[A case of fundus albipunctatus with a retinol dehydrogenase 5 gene mutation in a child].

BACKGROUND: We examined a family with fundus albipunctatus in which mutation of the retinol dehydrogenase 5(RDH 5) gene was suspected to be the cause of this disease. CASE: An 8-year-old girl had diffuse multiple white dots in her fundus except for the macula. She had good central vision. The amplitude of her electroretinogram wave was low, but it recovered after three hours of dark adaptation. Dark adaptometry showed an elevated threshold for rod adaptation. No visual field loss was observed. A homozygous missense mutation was found in exon 5 of the RDH 5 gene that substituted histidine for arginine at codon 280(Arg 280 His). Her mother had a normal fundus but was heterozygous for the same mutation. CONCLUSION: A missense mutation of RDH 5(Arg 280 His) was found in a Japanese family with fundus albipunctatus.

Alcohol Oxidoreductases↗

[On the educational benefits of biological sciences in space].

Experimental results in Space Sciences are getting accumulated. It may be advisable for the educational activities of our society that we inform young people, not only of each experimental result, but also of a variety of novel views of life and the world introduced by the researches in Biological Sciences in Space. We are going to provide a data-base including elementary words and concepts in these fields.

Biological Science Disciplines↗

Nitric oxide synthase is induced in tumor promoter-sensitive, but not tumor promoter-resistant, JB6 mouse epidermal cells cocultured with interferon-gamma-stimulated RAW 264.7 cells: the role of tumor necrosis factor-alpha.

Expression of inducible nitric oxide synthase (iNOS) has been reported to be involved in certain organs of potential tumorigenesis, including the stomach and colon. The mechanisms for iNOS expression in epithelial cells, however, are not fully understood. In the present study, we investigated the role of macrophages in epithelial iNOS expression by coculturing a stimulated murine macrophage-like cell line, RAW 264.7, with either tumor promoter-sensitive (P+) or promoter-resistant (P-) JB6 murine epidermal cells. After monoculture, treatment of RAW 264.7 cells with IFN-gamma for 24 h generated a large amount of nitrite (NO2-), as reported previously, whereas no increase in NO2- concentration was observed in the IFN-gamma-treated P+ or P-subclones. Interestingly, when IFN-gamma-treated RAW 264.7 cells were cocultured with P+ but not P- cells, we observed a marked increase in NO2- concentration (30.8+/-3.6 microM), which significantly exceeded (P < 0.01) the sum of the concentrations (20.0+/-2.3 microM) added from each cell line monoculture. Western blotting analysis revealed that, after coculture, iNOS protein was up-regulated 55-fold more than the control in JB6 P+ but not in P- cells. IFN-gamma-treated RAW 264.7 cells secreted proinflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta. The addition of IFN-gamma-treated RAW 264.7 cell-conditioned media to P+ subclones led to a significant enhancement of NO2- formation that was diminished by the TNF-alpha-specific but not IL-1beta-specific antibody. When combined with IFN-gamma, the recombinant TNF-alpha (1-100 ng/ml) enhanced NO2- formation in JB6 P+ cells, whereas IL-1beta (1-100 ng/ml) did not. These results led us to conclude that IFN-gamma-treated RAW 264.7 cells release TNF-alpha to induce iNOS expression in promoter-sensitive JB6 cells. Thus, we propose the hypothesis that macrophages stimulate neoplastic cells with TNF-alpha via a paracrine loop to induce epithelial iNOS protein expression.

Animals↗

Characterization of fission yeast cohesin: essential anaphase proteolysis of Rad21 phosphorylated in the S phase.

Cohesin complex acts in the formation and maintenance of sister chromatid cohesion during and after S phase. Budding yeast Scc1p/Mcd1p, an essential subunit, is cleaved and dissociates from chromosomes in anaphase, leading to sister chromatid separation. Most cohesin in higher eukaryotes, in contrast, is dissociated from chromosomes well before anaphase. The universal role of cohesin during anaphase thus remains to be determined. We report here initial characterization of four putative cohesin subunits, Psm1, Psm3, Rad21, and Psc3, in fission yeast. They are essential for sister chromatid cohesion. Immunoprecipitation demonstrates stable complex formation of Rad21 with Psm1 and Psm3 but not with Psc3. Chromatin immunoprecipitation shows that cohesin subunits are enriched in broad centromere regions and that the level of centromere-associated Rad21 did not change from metaphase to anaphase, very different from budding yeast. In contrast, Rad21 containing similar cleavage sites to those of Scc1p/Mcd1p is cleaved specifically in anaphase. This cleavage is essential, although the amount of cleaved product is very small (<5%). Mis4, another sister chromatid cohesion protein, plays an essential role for loading Rad21 on chromatin. A simple model is presented to explain the specific behavior of fission yeast cohesin and why only a tiny fraction of Rad21 is sufficient to be cleaved for normal anaphase.

Anaphase↗

Inhibitory effect of citrus nobiletin on phorbol ester-induced skin inflammation, oxidative stress, and tumor promotion in mice.

The intake of citrus fruits has been suggested as a way to prevent the development of some types of human cancer. Nitric oxide (NO) is closely associated with the processes of epithelial carcinogenesis. We attempted a search for NO generation inhibitors in Citrus unshiu. The active constituent was traced by an activity-guiding separation. NO and superoxide (O2-) generation was induced by a combination of lipopolysaccharide and IFN-gamma in mouse macrophage RAW 264.7 cells, and by 12-O-tetradecanoylphorbol-13-acetate (TPA) in differentiated human promyelocyte HL-60, respectively. Expression of inducible NO synthase and cyclooxygenase 2 proteins were detected by Western blotting. The in vivo anti-inflammatory and antitumor promoting activities were evaluated by topical TPA application to ICR mouse skin with measurement of edema formation, epidermal thickness, leukocyte infiltration, hydrogen peroxide production, and the rate of proliferating cell nuclear antigen-stained cells. As a result, nobiletin, a polymethoxyflavonoid, was identified as an inhibitor of both NO and O2- generation. Nobiletin significantly inhibited two distinct stages of skin inflammation induced by double TPA application [first stage priming (leukocyte infiltration) and second stage activation (oxidative insult by leukocytes)] by decreasing the inflammatory parameters. It also suppressed the expression of cyclooxygenase-2 and inducible NO synthase proteins and prostaglandin E2 release. Nobiletin inhibited dimethylbenz[a]anthracene (0.19 micromol)/TPA (1.6 nmol)-induced skin tumor formation at doses of 160 and 320 nmol by reducing the number of tumors per mouse by 61.2% (P < 0.001) and 75.7% (P < 0.001), respectively. The present study suggests that nobiletin is a functionally novel and possible chemopreventive agent in inflammation-associated tumorigenesis.

Animals↗

A glutathione S-transferase inducer from papaya: rapid screening, identification and structure-activity relationship of isothiocyanates.

We have developed a simple system for rapid detection and measurement of glutathione S-transferase placental form (GSTP1) that detoxify polycyclic aromatic hydrocarbons using the cultured rat normal liver epithelial cell line, (RL34) cells. Survey of fruit extracts for GST inducing ability identified both papaya and avocado as significant sources. Benzyl isothiocyanate (BITC) was isolated from papaya methanol extract as a principal inducer of GST activity. Further, the GST inducing ability of a total of 20 isothiocyanates (ITCs) and their derivatives was investigated. Some ITCs showed significant induction, and BITC was one of the most potent inducers among all compounds tested in the present study. The modification of isothiocyanate group (-NCS) or introduction of substituent group to the alpha-carbon modifies GST induction. Moreover, a significant correlation (P<0.01, r=0.913) between the GST activity enrichment and GSTP1 protein induction by ITCs was observed. We also indicated that phenethyl ITC and nitrophenyl ITC, potently inducing GST activity, but not inactive benzyl isocyanate, are potential inducers of intracellular reactive oxygen intermediates (ROIs). Our system of GSTP1 induction is appropriate for the chemical research such as screening and identification of novel type of inducers as well as the structure-activity relationship studies, providing mechanistic insight into essential structural elements for GSTP1 induction.

Animals↗

Suppressive effects of novel ferulic acid derivatives on cellular responses induced by phorbol ester, and by combined lipopolysaccharide and interferon-gamma.

A total of 23 ferulic acid (FA) derivatives were synthesized, and investigated for their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate-induced Epstein-Barr virus (EBV) activation and superoxide (O(2)(-)) generation. Most of the derivatives showed significant EBV activation suppression or cytotoxicity at a concentration of 100 microM, with FA15 as the most potent suppressor. In both assays, FA6-FA17, bearing straight- or branched-alkyl side chains, exhibited marked suppression of O(2)(-) generation, with both FA16 and FA17 being highly active, while FA itself was virtually inactive. The activity differences seen between FA16/FA17 and FA are attributable, at least in part, to their cellular incorporating efficiencies. Further, both FA15 and FA21 attenuated the expression of inducible nitric oxide synthase and cyclooxygenase-2 proteins, while FA did not. Our results suggest that these novel FA derivatives are effective chemopreventive agents.

Animals↗

Synthesis of feruloyl-myo-inositols and their inhibitory effects on superoxide generation.

Ester compounds consisting of ferulic acid and myo-inositol, obtained from rice bran, were synthesized. The inhibitory effects of these feruloyl-myo-inositols on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced superoxide (O2-) generation were examined using differentiated HL-60 cells. Among the derivatives tested, only 3,4,5,6-tetra-O-acetyl-1,2-di-O-[3-(4'-acetoxy-3'-methoxyphenyl)-2-pr openoyl]-myo-inositol (3) showed a distinct inhibitory activity.

Anticarcinogenic Agents↗