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  • Chemistry  (23)
  • Polymer and Materials Science  (8)
  • Life and Medical Sciences  (5)
  • Islet of Langerhans  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Nitric oxide is not involved in the initiation of insulin secretion from rat islets of Langerhans (1992)
    Springer
    Diabetologia 35 (1992), S. 1020-1027 
    Details
    ISSN: 1432-0428
    Keywords: Islet of Langerhans ; insulin secretion ; nitric oxide ; cyclic guanosine monophosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The involvement of nitric oxide as an intracellular messenger in the control of insulin secretion from pancreatic Beta cells was studied in rat islets of Langerhans by measuring: (i) nitric oxide generation in response to physiological insulin secretagogues; (ii) the effects of inhibitors of nitric oxide synthesis on insulin secretory responses to physiological secretagogues, and on insulin synthesis; (iii) changes in islet cyclic guanosine monophosphate in response to secretagogues; (iv) the effects of exogenous cyclic guanosine monophosphate and dibutyryl cyclic guanosine monophosphate on insulin secretion from electrically permeabilised islets and from intact islets, respectively. These studies produced no evidence that nitric oxide generation is required for the initiation of insulin secretion by common secretagogues. However, the results of our experiments suggest that the generation of nitric oxide may be involved in long-term, glucose-dependent increases in cyclic guanosine monophosphate content of islet cells, although the physiological relevance of these changes requires further investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02221676
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  • 2
    Electronic Resource
    Electronic Resource
    The role of protein kinase C in insulin biosynthesis (1993)
    Springer
    Acta diabetologica 30 (1993), S. 99-104 
    Details
    ISSN: 1432-5233
    Keywords: Insulin synthesis ; Islet of Langerhans ; Northern blotting ; Phorbol ester ; Protein kinase C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Activation of protein kinase C (PKC) by the phorbol ester 4β-phorbol myristate acetate (4β-PMA) stimulated (pro)insulin biosynthesis in collagenase-isolated rat islets of Langerhans, as assessed by measuring the incorporation of [35S]cysteine into proinsulin and insulin after fractionation by high performance liquid chromatography. The stimulatory effects of 4β-PMA were observed at a substimulatory concentration of glucose (2 mM) but were not additive to the stimulatory effects of 20 mM glucose on insulin biosynthesis. Prolonged exposure to 4β-PMA caused a marked down-regulation of PKC activity in islets. PKC-depleted islets showed a much reduced biosynthetic response to 20 mM glucose, but this was caused, at least in part, by an enhanced basal rate of (pro)insulin synthesis. These elevations in the basal rate of insulin synthesis were not secondary to an inerease in the amount of preproinsulin mRNA in PKC-depleted islets since Northern blot analysis showed that prolonged exposure to 4β-PMA, and the subsequent loss of PKC activity, did not detectably alter basal levels of preproinsulin mRNA. These results suggest that the activation of PKC stimulates (pro)insulin synthesis in rat islets by enhancing translation of existing preproinsulin mRNA, and that this may play some part in the biosynthetic responses of β-cells to glucose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00578222
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  • 3
    Electronic Resource
    Electronic Resource
    Protein phosphorylation in the regulation of insulin secretion: the use of site-directed inhibitory peptides in electrically permeabilised islets of Langerhans (1995)
    Springer
    Acta diabetologica 32 (1995), S. 32-37 
    Details
    ISSN: 1432-5233
    Keywords: Islet of Langerhans ; Insulin secretion ; Protein phosphorylation ; Protein kinase C ; Protein kinase A ; Inhibitory peptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have used electrically permeabilised rat islets of Langerhans to investigate the role of protein phosphorylation in the regulation of insulin secretion using pseudosubstrate inhibitory peptides for cyclic AMP-dependent protein kinase (PKA) and for protein kinase C (PKC). The protein kinase inhibitor (PKI) peptide, PKI(6–22), completely inhibited the effects of cyclic AMP on islet PKA activity in vitro, on endogenous protein phosphorylation and on insulin secretion. This peptide had no significant effect on islet PKC activity in vitro, on CA2+-induced protein phosphorylation and on secretory responses to Ca2+ or to the PKC activator, 4β-phorbol myristate acetate (PMA). The PKC pseudosubstrate inhibitory peptide, PKC(19–36), caused a marked inhibition of islet PKC activity in vitro and inhibite PMA-induced insulin secretion without affecting secretory responses to cyclic AMP and Ca2+. These results demonstrate that PKA-and PKC-induced protein phosphorylation is obligatory for cyclic AMP-and PMA-stimulated insulin secretion, respectively, and suggest that there is little “crosstalk” between the response elements of the secretory pathways to the different, second messengers, at least after the generation of the messengers within the β-cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581042
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  • 4
    Electronic Resource
    Electronic Resource
    Eigenschaften von Chalkogen - Chalkogen-Bindungen, XVII. - Di- und Trisulfane mit sterisch anspruchsvollen Alkyl-Substituenten: Das erste trans-Dialkyldisulfan (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1811-1811 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260809
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  • 5
    Electronic Resource
    Electronic Resource
    Isothermal volume relaxation in aged polycarbonate measured by positron annihilation lifetime spectroscopy (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 762-768 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 positron annihilation lifetime spectroscopy (PALS) technique is used to measure volume relaxation in physically aged glassy polycarbonate. The relaxation times and activation energy calculated for the isothermal relaxations in the aged polycarbonate are greater than those parameters calculated for unaged polycarbonate. The activation energy of 8.2 kcal/mol in the aged polycarbonate is used to identify the phenyl group motion or the cooperative carbonate-phenyl interaction as the molecular features responsible for the thermally induced open volume relaxations. It is postulated that the open volume relaxation kinetics as measured by PALS can be used as a nondestructive indication of property differences between aged and unaged polycarbonate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301303
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal degradation of polymers. Part III. Vacuum pyrolysis of poly(m-aminostyrene); the products volatile at pyrolysis temperature which are liquid or gaseous at room temperaturePaper presented at Thermal Analysis Group of Society of Analytical Chemistry Burlington House, London, on November 13th, 1968. (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 13 (1969), S. 2033-2043 
    Details
    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 products obtained on degradation of poly(m-aminostyrene) in vacuo are described. The effect of molecular weight and pyrolysis temperature are discussed and the behavior of poly(m-aminostyrene) compared with that of polystyrene. Quantitative analytical methods using ultra-violet spectroscopy and gas liquid chromatography are described for m-aminostyrene and m-toluidine. The possible mechanisms of degradation to yield the products are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1969.070131001
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  • 7
    Electronic Resource
    Electronic Resource
    A positron annihilation lifetime study of isothermal structural relaxation in bisphenol-A polycarbonate (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 1541-1552 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Positron annihilation lifetime spectroscopy has been used to study the isothermal relaxation response of compression molded bisphenol-A polycarbonate at temperatures of 263, 273, and 303 K. The temperature dependence of both the lifetime and intensity of the ortho-Positronium (o-Ps) pickoff component is discussed in terms of ductile-to-brittle transition behavior and free volume theory. An additive exponential model and the Williams-Watt model were used to analyze the relaxation as a function of temperature and provided results consistent with the anticipated molecular mobility of polycarbonate at sub-Tg temperatures.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260605
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  • 8
    Electronic Resource
    Electronic Resource
    Decomposition of organic wastes by Sphaerotilus (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 5 (1963), S. 287-307 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sphaerotilus is usually present in biological waste treatment processes and is considered to be a nuisance organism because it may cause bulking of activated sludge. However, it may play an important role in the decomposition of putrescible organic matter in properly operated biological waste treatment processes. The research described herein is a study of the variety of types of organic compounds which may be decomposed by Sphaerotilus and the effect of some environmental factors upon the rate of decomposition. Although there are some types of compounds which cannot be decomposed by Sphaerotilus, it is shown that this organism is able to assimilate and oxidize a large variety of organic compounds and that it is tolerant of an extremely wide range of environmental conditions. The role of Sphaerotilus in biological waste treatment is discussed in the light of the data presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260050405
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  • 9
    Electronic Resource
    Electronic Resource
    New insights into the Stereochemistry of 3-AminothioacrylamidesDedicated to Professor Dr. Wolfgang Walter on the Occasion of his 75th Birthday. (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 46-49 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hitherto unknown stereochemistry of N,N,N′,N′-tetrasubstituted 2-arylthioacrylamides 1 has been determined by X-ray crystal analysis and systematic NMR-investigations. Provided that the 2-aryl group lacks ortho substituents, compounds 1 exist predominantly as Z-isomers. In contrast, the major isomer has an E-s-trans configuration if the 2-aryl group is ortho-substituted. Substitution of the 3-amino group of 1 by glycinates, giving 3-aminothioacrylamides 2, generally preserves the original stereochemistry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19953370110
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  • 10
    Electronic Resource
    Electronic Resource
    Structure of the deoxytetranucleotide d-pApTpApT and a sequence-dependent model for poly(dA-dT)Supplementary material on observed and calculated structure factors for d-pApTpApT is available from the authors. (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 513-533 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The x-ray structure of the hydrated ammonium salt of the deoxytetranucleotide d-pApTpApT was determined by Patterson and direct methods at a resolution of 1 Å. The crystal structure contains right-handed double-helical segments formed by complementary Watson-Crick-type hydrogen bonding between the adenine and thymine bases of neighboring molecules. The minihelix contains two base pairs. The chains are antiparallel. The A-T and T-A sequences have different phosphodiester conformations. The deoxyribose-pucker and the sugar-base orientation alternate along the chain depending on the nature of the base (3′-endo for purine and 2′-endo for pyrimidine). The extended structure is stabilized by base-base, base-sugar, and hydrogen-bond interactions. The minihelix of two base pairs provides starting coordinates for model-building studies of the dA-dT polymer. A B-DNA-type polymer structure is described, which has sequence-dependent alternations of both the deoxyribose pucker and the phosphate diester bridge conformation. Such sequence-dependent DNA structures, if present locally in regions such as operator sequences, could facilitate sequence-specific interactions. The crystal study also suggests possible geometrical parameters for the replication fork.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210304
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