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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 43 (1998), S. 1746-1751 
    ISSN: 1573-2568
    Keywords: ANTITHROMBIN III ; THROMBIN ; ACETALDEHYDE ; ALCOHOL ; ALCOHOLISM ; BLOOD COAGULATION
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The anticoagulant activity of antithrombin III(ATIII), as observed in a plasma-free system consistingof thrombin and fibrinogen, is readily reduced byacetaldehyde (AcH) at concentrations of 447, 89.4, and 17.9 mM. Whereas controlthrombin-fibrinogen mixtures clotted in 17.7 ±0.75 sec, ATIII prolonged clotting time to 55.0 ±1.75 sec on preincubation with thrombin for 30 min atroom temperature. On subsequent preincubation of ATIII with theAcH for 30 min at room temperature and passage of themixture through Sephadex G-25 minicolumns to removeexcess AcH, the eluates were tested for anticoagulant activity. Clotting times of 20.9 ± 1.0,32.3 ± 1.0, and 45.3 ± 1.6 sec wereobtained with 447, 89.4, and 17.9 mM AcH-ATIII mixtures,respectively. These data suggest that functional groupson ATIII, such as guanidiniums, aminos, and others aresusceptible to adduct formation with AcH, therebyaltering the shape and charge of the anticoagulant. Asa consequence of this type of reaction, an alteredmolecule of reduced biological activity may be produced.These experimental results may explain, in part, thereduction in ATIII levels reported by others in patientswith alcoholic liver disease.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 44 (1999), S. 1349-1355 
    ISSN: 1573-2568
    Keywords: ANTITHROMBIN III ; THROMBIN ; HEPARIN ; BLOOD COAGULATION ; ACETALDEHYDE ; ALCOHOL ; ALCOHOLISM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acetaldehyde (AcH) at preincubationconcentrations of 447, 89.4, and 17.9 mM potentiates theeffects of heparin on the clotting time of plasma. Whilecontrol plasma clotted in the range of 12.6 ± 0.1 to 13.8 ± 0.1 sec, and heparin-treatedplasma clotted in a range from 131.5 ± 2.5 to168.2 ± 1.2 sec, heparin that was preincubated atroom temperature for 30 min with 89.4 or 447 mM AcH didnot clot plasma in 300 sec. Heparin exposed to 17.9 mMAcH clotted plasma in 193 ± 1.1 sec. Ethanol ata 404 mM concentration also prolonged the clotting timeof heparin-treated plasma 〉300 sec, while 202 mM ethanol prolonged the clotting time ofheparin-treated plasma from 149.0 ± 2.0 sec to219.5 ± 1.7 sec. It is suggested that AcH altersthe tertiary structure of heparin by adduct formation,possibly by formation of cyclic acetals with iduronicand glucuronic acids, thereby more readily affectingbinding of the glycosaminoglycan to antithrombin IIIand/or thrombin, prolonging clotting time. Ethanol, which does not react covalently with heparin,might affect its conformation as a consequence of anorganic solvent effect. Protamine sulfate prolonged theclotting time of plasma from 13.6 ± 0.1 sec to 17.9 ± 0.2 sec. Protaminesulfate-treated heparin clotted plasma in 21.0 ±0.4 sec relative to heparin-treated plasma (160.4± 1.7 sec). In subsequent experiments,AcH-treated protamine sulfate extended the clotting time of protamine sulfate from17.9 ± 0 sec to 33.7 ± 0.6 sec. Prioraddition of protamine sulfate to AcH- heparin mixturesor heparin to protamine sulfate-AcH mixtures beforeaddition to plasma resulted in clotting times of 22.0± 0.4 sec and 24.1 ± 0.5 sec,respectively, relative to control clotting times of162.3 ± 2.6 sec for plasma-heparin mixtures.These results confirm both the reduction in coagulation time ofheparin-treated plasma by protamine sulfate and theprolongation of clotting time of plasma by protaminesulfate. Furthermore, and importantly, they indicatethat acetaldehyde-treated protamine sulfate is a more effectiveanticoagulant than protamine sulfate. It is suggestedthat reversible adduct formation between acetaldehyde,heparin, and protamine sulfate may occur as a meansexplaining the essentially identical coagulation time ofthese mixtures when added to plasma regardless of theorder of premixing. Ethanol (404 mM) did not influenceprotamine sulfate effects. Lastly, the potentiation of the anticoagulant function of heparin byacetaldehyde suggests that a structural modification ofthe glycosaminoglycan may occur in alcoholics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-2568
    Keywords: ALCOHOL ; COAGULATION ; FACTOR VII ; FACTOR IX ; ACETALDEHYDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The first metabolite of ethanol, acetaldehyde,has the ability to form adducts with proteins and altertheir function. It has been shown that acetaldehydereacts with various proteins of the blood coagulation pathway and, subsequently, produces aprolongation of the clotting time. This study evaluatedthe function of clotting proteins from the extrinsiccoagulation pathway (factor VII) and the intrinsiccoagulation pathway (factor IX) when preincubated withacetaldehyde as compared to a control and compared topreincubation with ethanol. Prior to use in a clottingassay, incubation times with acetaldehyde, ethanol, and the control were the same for both factorsVII and IX. An automatic fibrometer measured theclotting times. Factor VII preincubated withacetaldehyde prolonged the clotting time. However,factor IX preincubated with acetaldehyde actuallydecreased the clotting time. Of interest, both factorsVII and IX preincubated with acetaldehyde producedstatistically significant results when compared to thecontrol and ethanol. This experiment indicates thatacetaldehyde, in forming an adduct with proteins of theblood coagulation pathway, may induce a conformationalchange of factors VII and IX so as to either increase or decrease the clotting time. Therefore, it ispossible that some of the deranged coagulation inalcohol abusers may be a final net result of theinteraction of acetaldehyde and proteins of thecoagulation pathway.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3065-3077 
    ISSN: 0887-6266
    Keywords: polyurethanes ; AFM ; atomic force microscopy ; phase separation ; crosslinking ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polyurea urethanes was isothermally synthesized from toluene diisocyanate (TDI), water, and trifunctional poly(propylene oxide) in the temperature range of 50-150°C. Morphologies of the samples vary significantly as a function of reaction temperature. In this system, phase separation competes with polymerization and crosslinking. Both transmission electron microscopy and atomic force microscopy have shown a network type of structure for the 50°C samples, while the 150°C samples appear to be homogeneous. Infrared analysis shows that samples prepared at 150°C possess a morphology that is less strongly hydrogen bonded and has a broader distribution of hydrogen-bonded states compared to those prepared at lower temperatures. From this combination of techniques, it can be inferred that phase separation occurs faster than crosslinking at low temperatures; consequently, a phase-separated morphology forms. In contrast, crosslinking occurs faster than phase separation at higher reaction temperatures. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3065-3077, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 13 (1975), S. 1097-1113 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: After flowing in a dilatometer bulb for a small fraction of the duration of the transformation, a relaxed melt of poly(ethylene oxide) (M̄n = (5.9 ± 0.1) × 103) showed marked increases in isothermal crystallization rate. The extent of increase was greater when flow was imposed at modestly later stages rather than at the earliest stage of a crystallization. Kinetic parameters for the flow-induced crystallizations were obtained via modification of the conventional mathematical treatment of the kinetics of phase change, thereby allowing the analytical resolution of the overall process into flowinduced and quiescent components. Determination of the flow-induced crystallization parameters required independent determination of the kinetic parameters for quiescent crystallizations at that temperature. The Avrami exponents nf which characterized the flow-induced portions of the crystallizations were larger for those instances in which flow was imposed at the more advanced stages of the crystallizations, thus indicating a transition in crystallization mechanism. It is suggested that prior crystallinity present at the time of flow contributed to the crystallization by serving as a source of nucleation sites. However, in light of the experimental procedure employed, values of nf approximating 4 that were obtained are not susceptible to mechanistic interpretations now extant.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 2679-2681 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 633-634 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 497-513 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solutions of cellulose (degree of polymerization: 296 ± 16) in tris(ethylenediamine)cadmium(II)hydroxide-ethylenediamine-water (cadoxen), 1.015% (weight per volume) were diluted 1:1.5 with water. The ensuing isothermal precipitations were followed dilatometrically at temperatures ranging from 27.50 to 48.45°C. The precipitation data were characterized by a positive temperature coefficient. They generally conformed to a one-dimensional nucleation rate law; the Avrami exponents were close to unity. Alternatively, they fit a first-order reaction rate expression with respect to cellulose concentration. The low crystallinity of the precipitated cellulose leads to the interpretation of the kinetics in terms of the dissociation of a cellulose-cadoxen complex, rather than phase separation, as the rate-determining step. The nucleation rate law suggests a one-dimensional nonrandom cooperative chemical process, while the first-order rate law suggests a random process.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 2651-2661 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quasi-equilibrium model of a step-growth copolymer that crystallizes and interchanges structural units simultaneously is presented. Equilibrium values of counit-sequence-length distribution in the amorphous phase and degree of crystallinity are calculated in a system for which crystallite thickness is determined by nucleation. When applied to calculations, the model predicts that the counits of the amorphous phase will tend to be ordered in blocks. The crystalline content of the whole polymer and the extent of ordering counits along the chain decreases with increasing temperature. The model predicts temperature ranges for some whole copolymers in which one of two similarly stable, disparate combinations of crystallinity and sequence-length distribution may prevail.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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