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Biomedical subjects

Y Sakagami

Publications and source records attributed to Y Sakagami.

At least 19 recordsLinked to original sources
PubMed2005

Antibacterial activity of alpha-mangostin against vancomycin resistant Enterococci (VRE) and synergism with antibiotics.

alpha-Mangostin, isolated from the stem bark of Garcinia mangostana L., was found to be active against vancomycin resistant Enterococci (VRE) and methicillin resistant Staphylococcus aureus (MRSA), with MIC values of 6.25 and 6.25 to 12.5 microg/ml, respectively. Our studies showed synergism between alpha-mangostin and gentamicin (GM) against VRE, and alpha-mangostin and vancomycin hydrochloride (VCM) against MRSA. Further studies showed partial synergism between alpha-mangostin and commercially available antibiotics such as ampicillin and minocycline. These findings suggested that alpha-mangostin alone or in combination with GM against VRE and in combination with VCM against MRSA might be useful in controlling VRE and MRSA infections.

Anti-Bacterial Agents↗
PubMed2002

Bactericidal activities of disinfectants against vancomycin-resistant enterococci.

The bactericidal activities of 35 commercially available disinfectants against vancomycin-resistant enterococci (VRE) and vancomycin-sensitive enterococci (VSE) were investigated under both clean and dirty (albumin added) conditions using a microtitration plate method. No differences in bactericidal time were observed with any of the test disinfectants when comparing activity against VRE or VSE. Isopropyl alcohol (70 v/v%), alcohol-containing preparations such as Welpas, Wellup and Maskin W . ethanol solution, 0.2% of cation surfactant disinfectants such as Osvan solution 'daigo', Germitol 'Maruishi' 10% and Hyamine solution, and 0.5% of amphoteric compound disinfectants such as TEGO-51, Hygieel and Hypal No.3, were the most effective compounds when compared with other disinfectants. These results suggest that the use of a disinfectant with activity against VRE may be one appropriate method for preventing infections caused by this micro-organism.

Anti-Bacterial Agents↗
PubMed2002

Antibacterial activity of calozeyloxanthone isolated from Calophyllum species against vancomycin-resistant Enterococci (VRE) and synergism with antibiotics.

Calozeyloxanthone ( 1) was re-isolated from the root bark of Calophyllum moonii, an endemic species of Sri Lanka, and found to be active against vancomycin-resistant Enterococci (VRE) and vancomycin-sensitive Enterococci (VSE) with MIC values of 6.25 microg/ml and 12.5 microg/ml, respectively. Further, a marked synergism between 1 and vancomycin hydrochloride (VCM) against VRE was also observed. These findings suggest that 1 in combination with VCM against VRE may be useful in controlling VRE infections.

Anti-Bacterial Agents↗
PubMed2001

Iantherans A and B, unique dimeric polybrominated benzofurans as Na,K-ATPase inhibitors from a marine sponge, Ianthella sp.

Two novel tetrabrominated benzofuran derivatives, named iantherans A and B, were isolated from an Australian marine sponge of the genus lanthella. The unique structures comprised of 2,3-bis(sulfooxy)-1,3-butadiene and two brominated benzofuran moieties were determined by spectroscopic and chemical methods. Iantheran A has a (Z,Z)-1,3-butadiene moiety, whereas iantheran B is the geometric isomer possessing a (Z,E)-1,3-butadiene moiety. The inhibitory activities of the iantherans and their derivatives against Na,K-ATPase as well as the efficacy of iantheran A against other several enzymes were evaluated.

Animals↗
PubMed2001

Neuritogenic cerebrosides from an edible Chinese mushroom. Part 2: Structures of two additional termitomycesphins and activity enhancement of an inactive cerebroside by hydroxylation.

Termitomycesphins E and F, novel cerebrosides that are hydroxylated around the middle of the long-chain base (LCB), have been isolated from the edible Chinese mushroom Termitomyces albuminosus (Berk.) Heim. ('Jizong' in Chinese) together with termitomycesphins A-D, and shown to induce neuronal differentiation in rat PC12 cells. Their stereostructures have been determined based on their chemical derivatization and spectroscopic analysis. The major cerebroside obtained from the same mushroom was not hydroxylated around the middle of the LCB and was inactive against PC12 cells, suggesting the importance of the extra hydroxyl group on LCB. The Di- and tetrahydroxylation of this inactive cerebroside resulted in the enhancement of its neuritogenic activity.

Agaricales↗
PubMed2001

Peptide signals and their receptors in higher plants.

At least four peptides play a vital role in plant cell-cell communication by means of their specific receptors. Two of these receptors have been identified as receptor kinases, which form a large family of receptor molecules in plants. These findings highlight the significance of receptor-mediated peptide signaling in various physiological events in plants, and predict the existence of further peptide-signal-interacting receptor kinases. Some candidates have been found in plant genomes. Here, we outline recent progress and future challenges in the signaling peptide analysis, which began with systemin, phytosulfokine, CLAVATA3 and S-locus cysteine-rich protein (also called S-locus protein 11).

Arabidopsis↗
PubMed2001

Biological activity of alpha-thujaplicin, the minor component of Thujopsis dolabrata SIEB. et ZUCC. var. hondai MAKINO.

Alpha-thujaplicin, a minor component of Thujopsis dolabrata SIEB. et ZUCC. var. hondai MAKINO, which was synthesized, showed the antibacterial activity, phytogrowth-inhibitory effect, inhibition of carboxypeptidase A and cytotoxic effect. Antibacterial activity of alpha-thujaplicin on Enterococcus faecalis IFO-12965 [minimum inhibitory concentration (MIC): 1.56 microg/ml] was higher than that of gentamicin (MIC: 6.25 microg/ml) used as a positive control. Inhibitory activity of alpha-thujaplicin on carboxypeptidase A [50% inhibitory concentration (IC50): 3.24 x 10(-5) M] was higher than that of 1,10-phenanthroline used as a positive control. Alpha-thujaplicin showed germination inhibition toward the seed of Echinochloa utilis Ohwi et Yabuno even at the low concentration of 10 ppm and its growth inhibitory effect was stronger than that of sodium 2,4-dichlorophenoxyacetate used as a standard. Alpha-thujaplicin at 1.25 microg/ml inhibited cell growth of human stomach cancer KATO-IIl by 86%, and Ehrlich's ascites carcinoma by 87%, respectively. This compound even at the low concentration of 0.32 microg/ml also inhibited cell growth of the former by 66%, and the latter by 75%, respectively. The acute toxicity of alpha-thujaplicin [50% lethal dose (LD50) value: 256 mg/kg] in mice was as strong as those of beta-dolabrin (LD50 value: 232 mg/kg) and gamma-thujaplicin (LD50 value: 277 mg/kg).

Animals↗
PubMed2001

New cyclic depsipeptide antibiotics, clavariopsins A and B, produced by an aquatic hyphomycetes, Clavariopsis aquatica. 1. Taxonomy, fermentation, isolation, and biological properties.

Clavariopsins were isolated from the fermentation broth of Clavariopsis aquatica AJ 117363. Clavariopsins are cyclic depsipeptide antibiotics with the molecular weight of 1,153 and 1,139. Clavariopsins showed in vitro antifungal activity against not only Aspergillus fumigatus but also, although to a lesser extent, A. niger and Candida albicans.

Animals↗
PubMed2001

New cyclic depsipeptide antibiotics, clavariopsins A and B, produced by an aquatic hyphomycetes, Clavariopsis aquatica. 2. Structure analysis.

The structures of new cyclic decadepsipeptides, clavariopsins A and B, were determined to be cyclo[-(R)-2-hydroxyisovaleryl-L-pipecoyl-L-MeVal-L-Val-L-MeAsp-L-MeIle-L-MeIle-Gly L-MeVal-L-Tyr(OMe)-] and cyclo[-(R)-2-hydroxyisovaleryl-L-pipecolyl-L-Val-L-Val-L-MeAsp-L-Melle-L-MeIle-Gly-L-MeVal-L-Tyr(OMe)-], respectively, by spectroscopic analyses, especially using 2D NMR techniques. The absolute stereochemistry was elucidated by the advanced Marfey's method and chiral HPLC analysis.

Anti-Bacterial Agents↗
PubMed2001

Diversity of Arabidopsis genes encoding precursors for phytosulfokine, a peptide growth factor.

Phytosulfokine-alpha (PSK-alpha), a unique plant peptide growth factor, was originally isolated from conditioned medium of asparagus (Asparagus officinalis) mesophyll cell cultures. PSK-alpha has several biological activities including promoting plant cell proliferation. Four genes that encode precursors of PSK-alpha have been identified from Arabidopsis. Analysis of cDNAs for two of these, AtPSK2 and AtPSK3, shows that both of these genes consist of two exons and one intron. The predicted precursors have N-terminal signal peptides and only a single PSK-alpha sequence located close to their carboxyl termini. Both precursors contain dibasic processing sites flanking PSK, analogous to animal and yeast prohormones. Although the PSK domain including the sequence of PSK-alpha and three amino acids preceding it are perfectly conserved, the precursors bear very limited similarity among Arabidopsis and rice (Oryza sativa), suggesting a new level of diversity among polypeptides that are processed into the same signaling molecule in plants, a scenario not found in animals and yeast. Unnatural [serine-4]PSK-beta was found to be secreted by transgenic Arabidopsis cells expressing a mutant of either AtPSK2 or AtPSK3 cDNAs, suggesting that both AtPSK2 and AtPSK3 encode PSK-alpha precursors. AtPSK2 and AtPSK3 were expressed demonstrably not only in cultured cells but also in intact plants, suggesting that PSK-alpha may be essential for plant cell proliferation in vivo as well as in vitro. Overexpression of either precursor gene allowed the transgenic calli to grow twice as large as the controls. However, the transgenic cells expressing either antisense cDNA did not dramatically decrease mitogenic activity, suggesting that these two genes may act redundantly.

Amino Acid Sequence↗
PubMed2000

120- and 160-kDa receptors for endogenous mitogenic peptide, phytosulfokine-alpha, in rice plasma membranes.

Plant cells in culture secrete a sulfated peptide named phytosulfokine-alpha (PSK-alpha), and this peptide induces the cell division and/or cell differentiation by means of specific high and low affinity receptors. Putative receptor proteins for this autocrine type growth factor were identified by photoaffinity labeling of plasma membrane fractions derived from rice suspension cells. Incubation of membranes with a photoactivable (125)I-labeled PSK-alpha analog, [N(epsilon)-(4-azidosalicyl)Lys(5)]PSK-alpha (AS-PSK-alpha), followed by UV irradiation resulted in specific labeling of 120- and 160-kDa bands in SDS-polyacrylamide gel electrophoresis. The labeling of both bands was completely inhibited by unlabeled PSK-alpha and partially decreased by PSK-alpha analogs possessing moderate binding activities. In contrast, PSK-alpha analogs that have no biological activity showed no competition for (125)I-AS-PSK-alpha binding, confirming the specificity of binding proteins. Analysis of the affinity of (125)I incorporation into the protein by ligand saturation experiments gave apparent K(d) values of 5.0 nm for the 120-kDa band and 5.4 nm for the 160-kDa band, suggesting that both proteins correspond to the high affinity binding site. Treatment of (125)I-AS-PSK-alpha cross-linked proteins with peptide N-glycosidase F demonstrated that both proteins contained approximately 10 kDa of N-linked oligosaccharides. Specific cross-linking of (125)I-AS-PSK-alpha was also observed by using plasma membranes derived from carrot and tobacco cells, indicating the widespread occurrence of the binding proteins. Together, these data suggest that the 120- and 160-kDa proteins are PSK-alpha receptors that mediate the biological activities of PSK-alpha.

Affinity Labels↗
PubMed2000

Existence of a plant tyrosylprotein sulfotransferase: novel plant enzyme catalyzing tyrosine O-sulfation of preprophytosulfokine variants in vitro.

An in vitro assay system to detect tyrosylprotein sulfotransferase (TPST) activity of higher plant cells was established, using synthetic oligopeptides based on the deduced amino acid sequence of a phytosulfokine-alpha (PSK-alpha) precursor. TPST activity was found in microsomal membrane fractions of rice, asparagus and carrot cells and it was confirmed that acidic amino acid residues adjacent to the tyrosine residues of acceptor peptides were essential to the sulfation reaction. The asparagus TPST exhibited a broad pH optimum of 7.0-8.5, required manganese ions for maximal activity and appeared to be a membrane-bound protein localized in the Golgi apparatus. These enzymes should be defined as a new class of plant sulfotransferases that catalyze tyrosine O-sulfation of a PSK-alpha precursor and other unknown proteins.

Amino Acid Sequence↗
PubMed2000

Peptide growth factor phytosulfokine-alpha contributes to the pollen population effect.

Density-dependent pollen germination and tube growth in vitro is a well-documented phenomenon, termed the pollen population effect, but far less is known about its molecular basis. We present evidence to support phytosulfokine-alpha [Y(SO3H)IY(SO3H)TQ; PSK-alpha] as a native bioactive factor contributing to this effect. Mature pollen grains of Nicotiana tabacum L. var. macrophylla were incubated in liquid medium for 2 h. Pollen germination frequency increased in a density-dependent manner from 625 to 46,000 grains/ml. Conditioned medium, obtained from the medium of pollen cultured at a density of 10,000 pollen grains/ml for 12 h, promoted the germination of pollen cultured at a low density (625 grains/ml). A rabbit antiserum against PSK-alpha specifically inhibited the promotive effect of conditioned medium. Quantification by enzyme-linked immunosorbent assay showed that the conditioned medium contained 0.4 nM of PSK-alpha. Exogenous PSK-alpha also stimulated pollen germination in the low-density culture. These results indicate that PSK-alpha is an important regulator involved in the pollen population effect.

Cells, Cultured↗
PubMed2000

Molecular cloning and characterization of OsPSK, a gene encoding a precursor for phytosulfokine-alpha, required for rice cell proliferation.

We previously characterized an OsPSK cDNA encoding a precursor of phytosulfokine-alpha (PSK-alpha), a peptide plant growth factor. Southern blot analysis suggested that OsPSK is a single-copy gene in rice, which we have isolated and characterized. The OsPSK gene consists of one large intron and two exons. The 5-amino acid PSK-alpha sequence located close to the COOH-terminus of the precursor is encoded in the second exon. A putative TATA box was found at position -68 with respect to the transcription initiation site. Upstream of this sequence, several potential regulatory elements, including one CAAT-box, three CCAAT-boxes, one enhancer core-like sequence, and three E-boxes could be identified. By constructing plasmids with various lengths of the 5'-upstream regions of the OsPSK gene fused to the coding sequence for bacterial beta-glucuronidase (GUS), we demonstrated a region 1.9 kb upstream of the transcription initiation point, which contains most of the putative 5'-regulatory elements, to be sufficient for maximal-level GUS expression in transformed rice Oc cells. The promoter of the OsPSK gene gave significantly higher levels of GUS expression than the CaMV 35S promoter. These results suggest that the OsPSK promoter could be useful for the constitutive expression of a foreign gene at high levels in transformed rice culture cells. Northern blot analyses suggest that the expression of OsPSK is reinforced by auxin and cytokinin.

Amino Acid Sequence↗
PubMed2000

A secreted peptide growth factor, phytosulfokine, acting as a stimulatory factor of carrot somatic embryo formation.

Somatic embryogenesis of the carrot (Daucus carota L.) depends on a set of factors, some of which accumulate in culture medium (conditioned medium, CM). When embryogenic cell clusters were transferred to an embryo-inducing medium, addition of CM derived from somatic embryo culture markedly stimulated somatic embryo formation. The active principles were purified using a simple bioassay system and identified to be phytosulfokines (PSKs), sulfated oligopeptide growth factors originally isolated from a CM derived from asparagus (Asparagus officinalis L.) mesophyll culture. Quantification studies using a competition ELISA system employing an anti-PSK-alpha polyclonal antibody showed that PSK production might be related to growth of cells, rather than development of somatic embryos. Thus the stimulatory effect of PSK on somatic embryo formation might be due to promotion of cell proliferation.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2000

A rapid and efficient system of Agrobacterium infection-mediated transient gene expression in rice Oc cells and its application for analysis of the expression and antisense suppression of preprophytosulfokine, a precursor of phytosulfokine-a, encoded by OsPSK gene.

A rapid and efficient system for Agrobacterium infection-mediated transient gene expression in rice has been developed. Using this system, transient expression of preprophytosulfokine, a precursor of phytosulfokine-a, encoded by OsPSK gene was analyzed. The results suggest that the Agrobacterium infection-mediated transient gene expression system is as efficient in rice Oc cells as in tobacco BY-2 cells and might be useful for rapid analysis not only of foreign gene expression, but also of antisense gene suppression.

Actins↗
PubMed2000

Phytosulfokine-alpha, a peptide growth factor found in higher plants: its structure, functions, precursor and receptors.

Phytosulfokine-alpha, a sulfated pentapeptide growth factor universally found in both monocotyledons and dicotyledons, strongly promotes proliferation of plant cells in culture. It is similar to animal polypeptide hormones in that it is processed from a larger precursor, preprophytosulfokine, although the putative processing sites do not conform to consensus sequences for endoproteolytic processing sites flanking animal prohormones. Like the animal preprohormones, preprophytosulfokine also has a signal peptide at the N-terminus for targeting to secretory pathways. The preprophytosulfokine gene has been confirmed to be expressed in vivo as well as in vitro.

Amino Acid Sequence↗