Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Biologisch Aktive Glycoside aus Asteroidea, III1,-Steroid-Oligoglycoside aus dem Seestern Acanthaster planci L., 2 -Strukturen von zwei neu charakterisierten genuinen Sapogeninen und einem Oligoglycosid-sulfatAus Seesternen (Acanthaster planci L.) wurde ein labiles Glycosid-Sulfat vom Typ 20-Hydroxycholesten-23-on in großen Mengen zur Strukturaufklärung isoliert. Abgesehen von dem bekannten 3β,6α-Dihydroxy-5α-pregn-9(11)-en-20-one (1) wurden erstmalig zwei neue genuine Aglyca bei der enzymatischen Hydrolyse der rohen Oligoglycosidfraktion isoliert. Auf Grund der chemischen und spektrometrischen Untersuchungen ließen sich die Strukturen als 3β,6α,20ξ-Trihydroxy-5α-cholest-9(11)-en-23-one (2) und 3β,6α,20ξ-Trihydroxy-5α-cholesta-9(11),24-dien-23-one (3) festlegen. Die Struktur eines als Acanthaglycosid A benannten neuen Pentaglycosid-Sulfats wurde als 3β-Natriosulfonatooxy-6α,20ξ-dihydroxy-23-oxo-5α-cholesta-9(11),24-dien-6α-yl-O-β-D-fucopyranosyl-(1→2)-O-β-D-quinovopyranosyl-(1→4)-O-[β-D-quinovopyranos-yl-(1→2)]-O-β-D-xylopyranosyl-(1→3)-O-β-D-quinovopyranosid identifiziert. Neben den konventionellen analytischen Methoden wurde erstmals die Fast-atom-bombardment-Massenspektrometrie (FAB-MS) für die Bestimmung und Absicherung der Struktur der natürlich vorkommenden Oligoglycosid-Sulfate benutzt
    Notes: From the whole bodies of Acanthaster planci L. a genuine oligoglycoside which is an unstable type 20-hydroxycholesten-23-one glycoside sulfate has been isolated in large quantities. Apart from the known 3β,6α-dihydroxy-5α-pregn-9(11)-en-20-one (1) two new genuine aglycones were isolated by enzymatic hydrolysis of the crude oligoglycoside fraction for the first time. The structures were identified by chemical and spectroscopic evidence to be 3β,6α,20ζ-trihydroxy-5α-cholest-9(11)en-23-one (2) and 3β,6α,20ξ-trihydroxy-5α-cholesta-9(11),24-dien-23-one (3), respectively. The structure of the newly characterized pentaglycoside sulfate Acanthaglycoside A was then determined to be 3β-sodiosulfonatooxy-6α,20ξ-dihydroxy-23-oxo-5α-cholesta-9(11),24-dien-6α-ylO-β-D-fucopyranosyl-(1→2)-O-β-D-quinovopyranosyl-(1→4)-O-[β-D-quinovopyranosyl-(1→2)]-O-β-D-xylopyranosyl-(1→3)-O-β-D-quinovopyranoside (4). Apart from conventional analytical methods, fast atom bombardment mass spectrometry (FAB-MS) was successfully used for the first time for determination and confirmation of the structure of the natural oligoglycoside sulfate.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The shifts in membrane potential, caused by the injection of some amino acids into a permeation cell, were measured using immobilized serum albumin membranes at isoelectric points of the amino acids. The effective fixed charge density was estimated to decrease after the injection of alamine, phenylalanine, and tryptophan and to increase after the injection of serine. The change in the fixed charge density originated from the conformational change of the immobilized albumin membranes induced by the binding between the albumin and amino acids in the membranes, since the conformational change of the immobilized albumin membranes induced by the binding of the amino acids to the serum albumin was observed from circular dichroism measurements. There was found, however, some discrepancy between the conformational change of the serum albumin in the albumin membranes detected by the membrane potential measurements and the circular dichroism measurements. This is explained by the fact that the circular dichroism measurements detect the increase or decrease in the α-helix, β sheet, and random coil contents; however, they do not always contribute to the detection of the change in the charge density due to the presence of the amino acid in the albumin membranes. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Addiction 99 (2004), S. 0 
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: This paper presents an outline of the Japanese Society of Alcohol-Related Problems. The precursor of the Society was the Japan Alcoholism Treatment Research Group, inaugurated in 1979, by merging two local research groups in the Tokyo and Osaka areas, both of which were exclusive gatherings of psychiatrists associated with alcoholism clinics. The Research Group developed into the Society in 1992, as the number of participants including those from other medical professions increased yearly, and the subjects of the group widened to include all addictive behaviours. In reflecting the process of establishment, it is unique in many aspects as a scientific society. The Society is not a science-orientated body for presentation of new research findings. The main programme of the annual meeting is therefore a set of symposia in which members participate and discuss clinical and/or social problems arising from dependency on alcohol or drugs. Perhaps because of its content, the annual meeting is attended each year by the largest number of participants among all the societies in Japan concerned with alcohol and drugs. For the next several years, the Society's activities will be directed at (1) establishment of guidelines for early identification of and intervention in alcohol-related problems; (2) expansion of its membership to include those in related fields of medicine and non-medical professions; (3) improvement of the system of journal publication; and (4) creation of a system for timely adequate response to social problems associated with drugs and alcohol.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Staphylococcal LukF and Hlg2 are water-soluble monomers of γ-haemolysin that assemble into oligomeric pores on the erythrocyte membranes. Here, we have created double-cysteine LukF mutants, in which single disulphide bonds connect either the prestem domain and the cap domain (V12C-T136C, Cap–Stem), or two β-strands within the prestem domain (T117C-T136C, Stem–Stem) to control pore assembly of γ-haemolysin at intermediate stages. The disulphide-trapped mutants were inactive in erythrocyte lysis, but gained full haemolytic activity if the disulphide bonds were reduced. The disulphide bonds blocked neither the membrane binding ability nor the intermediate prepore oligomerization, but efficiently inhibited the transition from prepores to pores. The prepores of Cap–Stem were dissociated into monomers in 1% SDS. In contrast, the prepores of Stem–Stem were stable in SDS and had ring-shaped structures similar to those of wild-type LukF, as observed by transmission electron microscopy. The transition of both mutants from prepores to pores could even be achieved by reducing disulphide bonds at low temperature (2°C), whereas prepore oligomerization was effectively inhibited by low temperature. Finally, real-time transition of Stem–Stem from prepores to pores on ghost cells, visualized using a Ca2+-sensitive fluorescent indicator (Rhod2), was shown by the sequential appearance of fluorescence spots, indicating pore-opening events. Taken together, these data indicate that the prepores are legitimate intermediates during γ-haemolysin pore assembly, and that conformational changes around residues 117 and 136 of the prestem domain are essential for pore formation, but not for membrane binding or prepore oligomerization. We propose a mechanism for γ-haemolysin pore assembly based on the demonstrated intermediates.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0947-3440
    Keywords: Glycosphingolipids ; Gangliosides ; Starfish ; Astropecten latespinosus ; Antitumor activity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two ganglioside molecular species [LG-1 (1) and LG-2 (5)] have been obtained from the water-soluble lipid fraction of the chloroform/methanol extract of the starfish Astropecten latespinosus. On the basis of chemical and spectroscopic findings, the structure of 1 and 5 have been elucidated. They are new ganglioside molecular species. Negative FAB mass spectrometry provided important information both on the structure of the sugar moiety and on the molecular mass of the gangliosides. Partial hydrolysis by hot water has proved useful for structure elucidation of the complex oligosaccharide moieties. In addition, the major ganglioside molecular species, LG-2 (5), shows antitumor activity against murine lymphoma L1210 cells in vitro.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyanions with various charge densities with a solvatochromic acid-base indicator dye attached to the main chain were prepared by the terpolymerization of acrylic acid, acrylamide, and a small mole fraction of 1-(2-methacryloyloxyethyl)-4-(2-(4-hydroxyphenyl)ethenyl)pyridinium bromide. The apparent pK value for the polymer-bound indicator dye (pKabs) was determined by the spectroscopic pH titration. The interfacial electrostatic potential (ψ) was calculated from pKobs. Dielectric contribution to the acid-base equilibrium was taken into account for the calculation. The electrostatic potentials thus obtained were compared with those calculated from the nonlinearized Poisson-Boltzmann equation for a cylinder model. The indicator dye moieties are suggested to be reporting the mean field potential at a distance of about 10 Å from the axis of the polyion cylinder. The observed values as a function of the charge density were also discussed in connection with Manning's theory.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0887-624X
    Keywords: polyanions ; counterion condensation ; pH-sensitive merocyanine dye ; poly(acrylic acid-co-acrylamide) ; charge density parameters ; Manning's theory ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of monovalent and divalent counterions on the acid-base equilibrium of a pH-sensitive merocyanine dye covalently attached to copolymers of acrylic acid and acrylamide with varying charge densities (0.28 〈 ξ 〈 2.8) were investigated. Added chloride salts of Li+, Na+, K+, and NH+4 (〈 0.2 mM) had essentially no effect on pK observed (pKobs) for the equilibrium. By contrast, the salts of Mg2+, Ca2+, Sr2+, and Ba2+ caused a significant decrease in pKobs for the copolymers with larger ξ. With smaller ξ, most likely when ξ 〈 0.5, no decrease in pKobs was observed upon addition of the salts of divalent cations. A competitive effect of Ca2+ and Na2+ ions on pKobs in the presence of an excess of Na+ ions implied that Ca2+ ions at very low concentrations were preferentially, and therefore exhaustively, condensed on the polyanions with sufficiently large ξ probably until effective charge density was lowered to 0.5. The observed difference in the influence of the monovalent and divalent cations on pKobs was discussed in terms of the difference in the microscopic behavior of the condensed monovalent and divalent cations. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Membrane depolarization stimuli (high potassium concentration and veratridine) increased neuropeptide Y (NPY) mRNA abundance time-dependently, without a change in β-actin mRNA level, in NG108-15 and PC12 cells. Although the induction by veratridine was blocked completely by tetrodotoxin, the induction by potassium was suppressed minimally. Voltage-dependent Ca channel blockers and calmodulin antagonists inhibited the increases by both depolarization stimuli completely, suggesting involvement of Ca2+/calmodulin-dependent kinases (CaM kinases). Transient assay using chloramphenicol acetyltransferase reporter genes containing the rat NPY gene promoter indicated that membrane depolarization and Ca entry stimulate transcription of the NPY gene. The depolarization-induced transactivation was also blocked by CaM kinase inhibitors. The 200-bp 5′-upstream region (−344/−145) was localized as a Ca2+/calmodulin-responsive element (CaMRE), which confers depolarization-induced transactivation. It is interesting that this CaMRE did not contain the canonical Ca-responsive elements such as CRE, SRE, NF-AT, or the C/EBPβ-binding site and was separated from a 64-bp cyclic AMP/phorbol 12-myristate 13-acetate-responsive element (−144/−81). These findings suggested that membrane depolarization regulates the NPY gene transcription positively through the unique CaMRE by activation of CaM kinases following Ca entry through L-type Ca channels.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The net primary production of tropical forests and its partitioning between long-lived carbon pools (wood) and shorter-lived pools (leaves, fine roots) are of considerable importance in the global carbon cycle. However, these terms have only been studied at a handful of field sites, and with no consistent calculation methodology. Here we calculate above-ground coarse wood carbon productivity for 104 forest plots in lowland New World humid tropical forests, using a consistent calculation methodology that incorporates corrections for spatial variations in tree-size distributions and wood density, and for census interval length. Mean wood density is found to be lower in more productive forests. We estimate that above-ground coarse wood productivity varies by more than a factor of three (between 1.5 and 5.5 Mg C ha−1 a−1) across the Neotropical plots, with a mean value of 3.1 Mg C ha−1 a−1. There appear to be no obvious relationships between wood productivity and rainfall, dry season length or sunshine, but there is some hint of increased productivity at lower temperatures. There is, however, also strong evidence for a positive relationship between wood productivity and soil fertility. Fertile soils tend to become more common towards the Andes and at slightly higher than average elevations, so the apparent temperature/productivity relationship is probably not a direct one. Coarse wood productivity accounts for only a fraction of overall tropical forest net primary productivity, but the available data indicate that it is approximately proportional to total above-ground productivity. We speculate that the large variation in wood productivity is unlikely to directly imply an equivalent variation in gross primary production. Instead a shifting balance in carbon allocation between respiration, wood carbon and fine root production seems the more likely explanation.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...