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  • 11
    Digitale Medien
    Digitale Medien
    Sleep induction by an adrenal steroid in the rat (1987)
    Springer
    Psychopharmacology 93 (1987), S. 226-229 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Benzodiazepines ; Barbiturates ; Steroids ; Chloride channel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ring A reduced metabolites of deoxycorticosterone and progesterone, 3alpha,5alpha-tetrahydrodeoxycorticosterone (THDOC) and 3alpha-hydroxy-5alpha-dihydroprogesterone (3alpha-OH-DHP) have been shown to be potent barbiturate-like ligands of the benzodiazepine receptor complex. The former has also been reported to have anxiolytic effects in mice and rats. In the present study, sleep recordings were obtained on rats given 5 and 10 mg/kg of these steroids alone and in combination with flurazepam. THDOC, but not 3alpha-OH-DHP, had potent dose-dependent sleep-inducing properties and increased nonREM sleep. Flurazepam had similar hypnotic effects and also reduced REM sleep. There were no significant interactions between THDOC and flurazepam, except in the case of REM latency, which tended to increase when the two compounds were given together. In summary, THDOC, a mineralocorticoid metabolite found in brain, has sedative properties and could conceivably play a role in stress responses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00179939
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  • 12
    Digitale Medien
    Digitale Medien
    Regulation in tobacco callus of enzyme activities of the nicotine pathway (1986)
    Springer
    Planta 168 (1986), S. 402-407 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Methylputrescine oxidase ; Nicotiana ; Nicotine biosynthesis ; Ornithine decarboxylase ; Putrescine methyltransferase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nicotine synthesis was stimulated by reduction of the medium auxin concentration (induction medium) in callus tissue originating from Nicotiana tabacum cv. Samsun. The enzyme activities of the route ornithine to methylpyrroline, which are those of ornithine decarboxylase, putrescine methyltransferase and methylputrescine oxidase, were determined during callus growth in the induction medium and as a control under non-nicotine-stimulating conditions (growth medium). The enzymes were assayed by high-performance liquid chromatography. Whereas the activities of ornithine decarboxylase were very similar under nicotine-stimulating and non-stimulating conditions, those of putrescine methyltransferase and methyl-putrescine oxidase increased strongly in the induction medium. In addition, the pools of putrescine and methylputrescine were determined throughout the callus growth cycle. Both sets of data strongly confirm the supposition that putrescine methyl-transferase is the enzyme under stringent control for nicotine biosynthesis, whereas the subsequent methylputrescine oxidase is co-regulated, although less stringently.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00392368
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  • 13
    Digitale Medien
    Digitale Medien
    Regulation in tobacco callus of enzyme activities of the nicotine pathway (1986)
    Springer
    Planta 168 (1986), S. 408-413 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Callus culture (nicotine pathway) ; Nicotiana (nicotine pathway) ; Nicotine biosynthesis ; Pyridine nucleotide cycle ; Pyridine nucleotide glycohydrolase ; Quinolinic acid phosphoribosyltransferase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In tobacco callus, the induction of nicotine synthesis, which stimulates enzyme activities of the ornithine-methylpyrroline route (see the preceding paper), also leads to marked changes in the enzyme activities of the pyridine-nucleotide cycle. This cycle provides the metabolite (probably nicotinic acid) for condensation with methylpyrroline to produce nicotine. The activities of eight enzymes of the pyridine-nucleotide cycle and of quinolinic-acid phosphoribosyltransferase, the anaplerotic enzyme, were determined by high-performance liquid chromatography assays. The distinct changes of their activities upon induction of nicotine synthesis lead to the following conclusions: i) nicotinic acid is the relevant metabolite which is provided by the pyridine-nucleotide cycle and consumed for nicotine synthesis. ii) The enhancement of the nicotinic-acid pool arises in two ways, by synthesis of NAD and degradation via nicotinamide mononucleotide and by a direct route from nicotinic-acid mononucleotide (NaMN) which is degraded by a glycohydrolase with a rather high K m value. Such a K m value prevents the complete depletion of the NaMN pool.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00392369
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  • 14
    Digitale Medien
    Digitale Medien
    The pyridine-nucleotide cycle in tobacco Enzyme activities for the de-novo synthesis of NAD (1985)
    Springer
    Planta 165 (1985), S. 532-537 
    Details
    ISSN: 1432-2048
    Schlagwort(e): NAD-synthetase ; Nicotiana (pyridine nucleotides) ; Nicotinic acid mononucleotide adenyltransferase ; Pyridine nucleotide cycle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The enzyme activities of the pyridine-nucleotide cycle, which transform nicotinic acid mononucleotide (NaMN) into NAD, have been characterized. The investigations were based on the extraction of protein, its purification on disposable gel-filtration columns, and determination of the enzymatic activities by high-performance liquid chromatography techniques. The latter technique avoided the synthesis and use of radioactive precursors. The NaMN-adenylyltransferase which converts NaMN into NaAD (nicotinic acid adenine dinucleotide) and NAD-synthetase which converts NaAD into NAD were characterized by their kinetic parameters and their specific activities in different tobacco tissues. This is the first report on NAD-synthetase from tissue of a higher plant. It was found that NAD-synthetase accepted both glutamine and asparagine for the amide transfer. Adenylyltransfer also occured with nicotinamide mononucleotide (NMN) which was transformed to NAD, whereas the glutamine-dependent amidation was only observed with NaAD. Thus, an additional route for the synthesis of NAD (NaMN→NMN→NAD) obviously does not exist. A comparison of the enzyme activities in tobacco tissues with different capacities for the synthesis of nicotine showed that, in contrast to quinolinic acid phosphoribosyltransferase whose activity was strictly correlated with the nicotine content, only NaMN-adenylyltransferase showed a smooth correlation, whereas NAD-synthetase was not affected at all.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00398100
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  • 15
    Digitale Medien
    Digitale Medien
    The pyridine-nucleotide cycle in tobacco (1986)
    Springer
    Planta 167 (1986), S. 226-232 
    Details
    ISSN: 1432-2048
    Schlagwort(e): NAD pyrophosphatase ; Nicotinamidase ; Nicotiana (pyridine-nucleotide cycle) ; Nicotine biosynthesis ; Pyridine nucleotide cycle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to elucidate the NAD-recycling pathway the following enzyme activities have been characterized in different tobacco tissues and in tomato root: NAD pyrophosphatase, nicotinamide mononucleotide (NMN)/nicotinic acid mononucleotide (NaMN) glycohydrolases, nicotinamidase and nicotinic acid phosphoribosyltransferase. The investigations were performed with protein extracts purified by gel filtration and enzymatic activities were determined by high-performance liquid chromatography methods. The kinetic parameters of the different enzymes from tobacco root and their specificity are reported. The data are in favor of the so-called pyridine-nucleotide cycle VI (NAD→NMN→nicotinamide→nicotinic acid→NaMN→nicotinic acid adenine dinucleotide→NAD). In the nicotine-producing tobacco root a further direct route leading from NaMN to nicotinic acid is proposed. These data are reconciled with the assumption that it is nicotinic acid which is provided by the pyridine-nucleotide cycle for the synthesis of nicotine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00391419
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  • 16
    Digitale Medien
    Digitale Medien
    Polarized neutron scattering by polarized protons of bovine serum albumin in deuterated solvent (1989)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 22 (1989), S. 352-362 
    Details
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Bovine serum albumin (BSA) was dissolved in a mixture of deuterated glycerol and heavy water. The clusters formed by the 3300 proton spins in each BSA molecule were dynamically polarized up to P = 40%. Spin-contrast variation in small-angle neutron scattering was studied at several target polarizations. Zero contrast, and hence minimum polarized neutron small-angle scattering, is expected at PH = 60% from extrapolation of present data. The three basic scattering functions of spin-contrast variation look very similar because the shape of the BSA molecule and its proton distribution are congruent. Neutron small-angle scattering of BSA is similar to X-ray small-angle scattering at room temperature, indicating no deterioration of the molecular structure of BSA on solidification.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0021889889004073
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  • 17
    Digitale Medien
    Digitale Medien
    Onset of sublimation in comet P/Halley (1982i) (1985)
    [s.l.] : Nature Publishing Group
    Nature 316 (1985), S. 241-242 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Pre-perihelion spectrophotometric observations (wavelength (?) = 3,000-7,000 ‚,?/?? -250) covering a heliocentric distance (r) in the range 5.6-4.2 AU of comet P/Halley were obtained using the photon-counting Reticon spectrograph on the 4.5-m Multiple Mirror Telescope (MMT) of the F. L. Whipple ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/316241a0
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  • 18
    facet.materialart.
    Unbekannt
    A Noncooperative Solution to a Two-Person Bargaining Game (1986)
    Dordrecht : Periodicals Archive Online (PAO)
    Theory and Decision. 21:3 (1986:Nov.) 311 
    Details
    ISSN: 0040-5833
    Thema: Sociologie , Wirtschaftswissenschaften
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:n228-1986-021-03-000005
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  • 19
    Digitale Medien
    Digitale Medien
    Photopyroelectric spectroscopy (P2ES) of electronic defect centers in crystalline n-CdS (1987)
    Springer
    Applied physics 44 (1987), S. 123-130 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 72.20 ; 61.70
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Photopyroelectric spectroscopy (P2ES) of n-CdS single crystals was performed at an open circuit, and in conjunction with photocurrent spectroscopy (PCS) in the presence of an applied ac or dc transverse field. The results showed that P2ES is very sensitive to the presence of deliberately introduced subbandgap defect structures, with the P2E signal dominated by non-radiative de-excitation mechanisms at defect centers. The potential of this technique as a powerful electronic defect diagnostic tool, combined with the overall experimental simplicity, was demonstrated with mm-thick crystals used as received in an open-cell geometry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00626412
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  • 20
    Digitale Medien
    Digitale Medien
    Accumulation and incorporation of 185W-tungsten into proteins of Clostridium acidiurici and Clostridium cylindrosporum (1987)
    Springer
    Archives of microbiology 147 (1987), S. 295-299 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Clostridium acidiurici ; Clostridium cylindrosporum ; Tungsten uptake ; Molybdate antagonism ; Formate dehydrogenase ; Tungsten-binding-storage protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Uptake of tungstate by growing cells was unaffected by the presence of molybdate in Clostridium cylindrosporum, whereas in C. acidiurici the accumulation was decreased by molybdate at 10-6 mol/l tungstate and higher concentrations. The labelling pattern of soluble proteins by 185W-tungsten indicated after gel chromatography the presence of three different tungstoproteins in both bacteria. Formate dehydrogenase activity always eluted at a maximum of tungsten labelling. The incorporation of tungsten into formate dehydrogenase containing fractions and a possible tungsten-binding-storage protein was independent of the presence of excess molydate pointing to a genuine role for tungstate in these bacteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00463491
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