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  • Articles: DFG German National Licenses  (16)
  • Polymer and Materials Science  (13)
  • Key words Smooth muscle  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Volume-sensitive chloride current activated by hyposmotic swelling in antral gastric myocytes of the guinea-pig (1997)
    Springer
    Pflügers Archiv 435 (1997), S. 9-19 
    Details
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Cell volume ; Chloride current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The characteristics of volume-sensitive chloride current (I Cl) induced by osmotic cell swelling were studied using the whole-cell patch-clamp technique and cell diameters of antral circular guinea-pig myocytes were simultaneously measured under isosmotic and hyposmotic conditions by using a video image analysis system. At –60 mV, osmotic cell swelling (200 mosmol/l) activated a sustained inward current. Instantaneous current/voltage (I-V) relations obtained by step voltage pulses showed an outward rectification. At potentials above +40 mV, the current exhibited time-dependent decay. The outward current amplitude was decreased and the reversal potential was shifted to more positive potentials by replacement of external Cl– with gluconate–, while the current amplitude and the I/V relation were not affected by replacing extracellular Na+ with N-methyl-D-glucamine. The anion permeability sequence of the swelling-induced current was I– (1.80) 〉 Br– (1.31) 〉 Cl– (1) 〉 F– (0.85) 〉 gluconate– (0.18). The I Cl was effectively inhibited by the Cl– channel blockers, 4,4′-diisothiocyanatostilbene-2,2’-disulphonic acid (DIDS, 100 μM), and niflumic acid (10 μM). DIDS suppressed outward current more effectively than inward current. Also, the I Cl was dose-dependently inhibited by arachidonic acid, an unsaturated fatty acid and also inhibited by other unsaturated fatty acids (linoleic acid and oleic acid) but not by stearic acid, a saturated fatty acid. The inhibitory effect of arachidonic acid on I Cl was not prevented by indomethacin, a cyclo-oxygenase inhibitor and chelerythrine, a protein kinase C inhibitor. Under whole-cell patch-clamp conditions, the cell diameter was continuously measured using video image analysis, which reflects the change in cell volume. A hyposmotic-stimulation-induced increase of cell diameter was followed by I Cl activation. In intact single gastric myocytes, relatively severe hyposmotic (176 mosmol/l) superfusing solution increased the cell diameter and the pretreatment with DIDS or with niflumic acid significantly potentiated the above effect of hyposmotic superfusion. These results suggest that volume-sensitive outwardly rectifying chloride current (I Cl) is present in guinea-pig gastric myocyte and the I Cl may play a role in smooth muscle cell volume regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050478
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of myosin light chain kinase inhibitors on carbachol-activated nonselective cationic current in guinea-pig gastric myocytes (1997)
    Springer
    Pflügers Archiv 434 (1997), S. 346-353 
    Details
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Nonselective cationic current ; Carbachol ; Myosin light chain kinase ; ML-7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of myosin light chain kinase inhibitors on muscarinic stimulation-activated nonselective cationic current (I CCh) in guinea-pig gastric antral myocytes were studied using the whole-cell patch-clamp technique. I CCh was induced by carbachol (CCh, 50 μM) at a holding potential of –30 mV or –60 mV. ML-7, a chemical inhibitor of myosin light chain kinase (MLCK), inhibited I CCh concentration dependently in a reversible manner (53 ± 8.6% at 1 μM, mean ± SE, n = 11). In addition, amplitudes of I CCh were only 37 ± 2.7% of the daily control values following the addition of a peptide inhibitor of MLCK to the pipette solution. On the other hand, ML-7 had an inhibitory effect on voltage-operated Ca2+ channel current. The peak value of Ba2+ current at 0 mV was reduced to 35 ± 7.4% (n = 9) by 3 μM of ML-7. As I CCh is known to have an intracellular Ca2+ dependence, we tried to exclude the possibility that ML-7 inhibited I CCh indirectly via suppression of Ca2+ current and the similar inhibitory effects of ML-7 on I CChwere confirmed under the following conditions: (1) clamp of membrane potential at –60 mV; (2) clamp of intracellular [Ca2+] to 1 μM by 10 mM BAPTA; (3) pre-inhibition of Ca2+ channel by verapamil. Different from the effects on I CCh, ML-7 barely inhibited the same cationic current induced by guanosine 5’-O-(3-thiotriphosphate) (GTP[γS], 0.2 mM) in the pipette solution. These results suggest that a Ca2+/calmodulin-MLCK-dependent pathway can modulate the activation of I CCh in guinea-pig gastric antral myocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050407
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  • 3
    Electronic Resource
    Electronic Resource
    Protein kinase C mediates the desensitization of CCh-activated nonselective cationic current in guinea-pig gastric myocytes (1998)
    Springer
    Pflügers Archiv 436 (1998), S. 1-8 
    Details
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Nonselective cationic current ; Carbachol (CCh) ; Protein kinase C (PKC) ; Desensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The possibility of the protein kinase C (PKC) pathway being a mechanism underlying the desensitization of carbachol- (CCh-)activated nonselective cationic current (I CCh) was investigated in a study of guinea-pig gastric myocytes. Using the conventional whole-cell patch-clamp technique with symmetrical CsCl-rich solution in pipette and bath, I CCh was induced by bath application of 50 µM CCh. With 0.5 mM EGTA [ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid] in the pipette solution (0.5 mM [EGTA]i), I CCh decayed spontaneously (desensitization of I CCh) to around 20% within 10 min. Desensitization of I CCh was significantly attenuated with 2 mM [EGTA]i. At a concentration of 20 µM OAG (1-oleoyl-2-acetyl-sn-glycerol), a PKC activator, inhibited I CCh at 0.5 mM [EGTA]i but far less at 2 mM [EGTA]i (18% and 81% of control, respectively). The same cationic current induced by intracellular guanosine-5′-O-(3-thiotriphosphate) (GTP[γ-S]) was not inhibited by OAG with 0.5 mM [EGTA]i. The pretreatment of gastric myocytes with PKC inhibitors, either 1 µM chelerythrine or 1 µM peptide inhibitor, attenuated the desensitization of I CCh. [Ca2+]i was also measured by single cell microfluorometry using fura-2. Under CCh stimulation with 2 mM [EGTA]i, [Ca2+]i did not increase above 100 nM while it increased to around 260 nM with 0.5 mM [EGTA]i. These results suggest that the desensitization of I CCh is partly due to the Ca2+-dependent PKC pathway in guinea-pig gastric myocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050597
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  • 4
    Electronic Resource
    Electronic Resource
    Isomeric compositions in amide acids and poly(amic acid)s derived from 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1755-1765 
    Details
    ISSN: 0887-624X
    Keywords: 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride ; amide acid ; poly(amic acid) ; isomeric unit ; nuclear magnetic resonance spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two different poly(amic acid)s were synthesized by the polycondensations of 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (CF3DAN) with p-phenylene diamine and benzidine. In addition, an amide acid model compound was prepared from CF3DAN and aniline. Isomeric units in the poly(amic acid)s as well as the amide acid were investigated by 1H and 13C-nuclear magnetic resonance (NMR) spectroscopies. Spectroscopic results indicate that the major isomeric component was a CF3-meta-isomeric unit centered on the aromatic carbon substituted with the trifluoromethyl group. In particular, the amide acid compound was determined to be composed of 80 mol % CF3-meta-isomer and 20 mol % H-meta-isomer. Therefore, for the poly(amic acid)s, the minor isomeric component is speculated to be a H-meta-isomeric unit rather than a para-isomeric unit. The result might result mainly from the strong electron-withdrawable and bulky trifluoromethyl substituent in the CF3DAN monomer. The strong electron withdrawability might significantly enhance the reactivities of the adjacent carbons in the monomer to the nucleophilic attack of the amino nitrogen in the aniline and diamines, and consequently overcome the role of the bulkyness, ultimately leading to the amide acid and poly(amic acid)s rich with the CF3-meta-isomeric unit. In addition, a portion of the imide form was detected in the dried AN-CF3DAM-AN amide acid. Thus, the formation of imide linkage might be involved in a small portion for the dried poly(amic acid)s. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1755-1765, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Zur Viskosität von Glasschmelzen und porösen Sintergläsern (1995)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 26 (1995), S. 263-268 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Qn the viscosity of glass melts and porous sintered glassesSuspensions of solid phase particles in molten glasses modify their flow behavior and therefore their viscosity. This work deals with the dependence of the effective viscosity (ηeff) of isotropic suspensions on the concentration of the solid phase particles. Independently of the shape of the inclusions the values of the effective viscosities lie between upper [ηeff = ηL (1 - CD)-14 ]and lower bounds [ηeff = ηL (1 - CD)-3], where ηL is the viscosity of the molten glass and CD is the volume fraction of solid inclusions. The lower bound is also valid for the effective viscosity of suspensions containing spherical inclusions.Pores present in a glass matrix affect its flow behavior and consequently its creep and sintering behavior. The effective viscosity of porous glasses (ηP) as a function of the volume fraction of pores, or porosity (P), also varies between and upper [ηP = ηM (1 - P)1.04] and a lower bound [ηP = ηM (1 - P)14], where ηM is the viscosity of the nonporous glass matrix. For spherical porosity the equation is: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm \eta_P = \eta_M(1 - P)^{1.5}}$$\end{document}Measured values for the viscosity of different suspensions as reported in the literature as well as own experimental data on two glass-solid systems are compared with the theoretical values predicted by these equations. In a similar way literature data for the viscosity of porous sintered glasses are compared with the respective equations. In all cases a fair agreement between experiment and theory was found in some cases the agreement was excellent. Therefore the presented equations constitute a reliable approach for the prediction of the viscosity of suspensions and porous sintered glasses and since they do not contain fitting parameters, they are of substantial practical relevance (for a comprehensive english treatment of the matter compare Glastechnische Berichte, Proc. Otto-Schott-Colloquium 1994).
    Notes: Suspensionnen von Festphasenteilchen in Glasschmelzen verändern deren Fließverhalten und damit deren Viskosität. Die vorliegende Arbeit behandelt die Abhängigkeit der effektiven Viskosität (ηeff) isotroper Suspensionnen von der Konzentration der Festphansenteilchen. Unabhängig von deren Form liegen die effektiven Viskositäten zwischen oberen und unteren Grenzwerten, deren Konzentrationsabhängigkeit durch Näherungslösungen gegeben ist: obere Grenzwertgleichung: ηeff = ηL (1 - CD)-14untere Grenzwertgleichung: ηeff = ηL (1 - CD)-3(ηL = Viskosität der Schmelze; CD = Volumenanteil der Festphasenteilchen). Für die effektive Viskosität von Suspensionen mit sphärischen Festphasenteilchen gilt die untere Grenzwertgleichung.Poren in Sintergläsern verändern ebenfalls deren Fließ- und damit Sinter-, Umform- und Kriechverhalten. Die effektive Viskosität poröser Gläser (ηP) als Konzentrationsfunktion ist gegeben durch die Näherungslösungen: obere Grenzwertgleichung: ηP = ηM (1 - P)1.04untere Grenzwertgleichung: ηP = ηM (1 - P)14(ηM = Viskosität des porenfreien Glases; P = Porosität).IM Falle sphärischer Porosität gilt die Viskositätsgleichung \documentclass{article}\pagestyle{empty}\begin{document}$${\rm \eta_P = \eta_M(1 - P)^{1,5}}$$\end{document}Gemessene Werte der Viskosität diverser Suspensionen sowie von Na2O-SiO2-Schmelzen mit dispergierten festen SiO2-Teilchen und Na2O-GeO2-Schmelzen mit dispergierten GeO2-Teilchen werden ebenso mit berechneten Werten verglichen wie die experimentellen Werte der Viskosität von porösen Sintergläsern mit den entsprechenden theoretischen. In allen Fällen wurde hinreichende, vielfach beste Übereinstimmung festgestellt. Die Gleichungen liefern praxisrelevante, verläßliche Aussagen sowohl für Suspensionen wie für poröse Sintergläser.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19950260510
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  • 6
    Electronic Resource
    Electronic Resource
    Biomimetic synthesis of cadmium sulfide-ferritin nanocomposites (1996)
    Weinheim : Wiley-Blackwell
    Advanced Materials 8 (1996), S. 928-932 
    Details
    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: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19960081114
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  • 7
    Electronic Resource
    Electronic Resource
    The utilization of SANS to solve polymer latex structural problems: Basic science and engineering (1990)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 1 (1990), S. 263-273 
    Details
    ISSN: 1042-7147
    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
    Notes: Small-angle neutron scattering studies have been used to clarify several aspects of the internal structure of latexes and subsequent film formation modes. This paper reviews work both around the world and at Lehigh University on those subjects. Two points have been made clear: (1) The appearance of core-shell phenomena in latexes depends on the size of the polymer chain to that of the latex particle; the phenomenon is most marked when the radius of gyration of the chain is about one fifth as big as the latex radius. (2) Strength build-up during film formation depends on the extent of interdiffusion of the chains. For moderate molecular weights, interdiffusion distances of one radius of gyration yield maximum strength. For both moderate (250,000 g/mol) and high (2,000,000 g/mol) molecular weights, full strength was achieved in two hour's annealing time at 144°C.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1990.220010311
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of microstructure on dynamic mechanical behaviour of polymeric composites with complex inclusions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 305-322 
    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 dynamic mechanical properties of polymeric composites composed of crosslinked poly(n-butyl methacrylate) continuous-phase and crosslinked polystyrene dispersed phase with poly(n-butyl methacrylate) occlusion have been examined. The composite samples were prepared by mixing and swelling of the crosslinked polystyrene particles obtained by emulsifier-free emulsion polymerization, with n-butyl methacrylate and crosslinker, then photopolymerizing at the desired temperature. The composite microstructure was varied by either changing the crosslink density of polystyrene, and temperature of swelling and polymerization, or using different sizes and contents of polystyrene particles. The tan δ peak positions of composite samples are found to be dependent on morphological characteristics as well as the properties of the dispersed phase while the peak height seems to be dependent on the effective volume of dispersed phase composed of polystyrene and poly(n-butyl methacrylate) occlusions. Special attention has been paid to the comparison among composite, homonetworks, and bulk IPN samples that are expected to have the identical structure with the complex dispersed phase of the composite samples. © 1993 John Wiley & Sons, Inc.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470210
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  • 9
    Electronic Resource
    Electronic Resource
    Crosslinking of HDPE during reactive extrusion: Rheology, thermal, and mechanical properties (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 981-986 
    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 effect of peroxide and coagent, alone and together, on the crosslinking of HDPE during melt extrusion was studied. The melt flow index decreased rapidly with peroxide (1,3-bis (t-butylperoxy-isopropyl) benzene), and smoothly with trimethylolpropanetriacrylate (TMPTA), but showed a small increase with parabenzoquinone (PBQ).Melt viscosity of 0.3 phr peroxide-treated PE responded elastically, whereas that of 0.3 phr TMPTA showed yield behavior. Tm (crystalline melting temperature) and Tc (crystallization temperature) increased with peroxide, Tm decreased, and Tc increased with TMPTA. ΔHf (heat of fusion) increased at 0.05 phr followed by a sharp drop, more with peroxide and less with TMPTA. Hardness and preyield properties increased with TMPTA, and peroxide (except hardness) with the loss of elongation at break. The most significant improvement was obtained with impact strength, over 5 times with peroxide and 7 times with TMPTA.When the TMPTA was used in combination with peroxide, more redution in MI, followed by a further increase of hardness, modulus, and strength, was obtained, but impact strength was decreased below that of TMPTA alone. © 1993 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480605
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  • 10
    Electronic Resource
    Electronic Resource
    A comparison of measurements of the viscoelastic properties of polymer melts by means of the Han slit/capillary rheometer and the Weissenberg rheogoniometer (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 95-103 
    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: Measurements were taken of the viscoelastic properties of six polymer melts by mean of the Weissenberg rheogoniometer and the Han slit/capillary rheometer. Polymers in vestigated were three high-density polyethylenes of different polydispersity, a low-density polyethylene, a polypropylene, and a polystyrene. The range of shear rates tested was from about 5.0 × 10-3 to 10 sec-1 with the Weissenberg rheogoniometer, from about 10 to 102 sec-1 with the slit rheometer, and from about 102 and 103 with the capillary rheometer: the temperature of measurement was 200°C. The three different apparatuses give consistent results over almost six decades of shear rates, yielding satisfactory correlations of shear viscosity to shear rate and of normal stress difference to shear rate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170107
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