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  • 1985-1989  (8,397)
  • 1987  (8,397)
  • Chemistry  (8,271)
  • Chemical Engineering  (726)
  • pharmacokinetics  (127)
  • 101
    Electronic Resource
    Electronic Resource
    Phase I clinical trial and pharmacokinetics of weekly ICRF-187 (NSC 169780) infusion in patients with solid tumors (1987)
    Springer
    Investigational new drugs 5 (1987), S. 187-198 
    Details
    ISSN: 1573-0646
    Keywords: ICRF-187 ; phase I ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract ICRF-187 was given to 62 evaluable patients with advanced solid tumors in a Phase I clinical trial. Weekly infusions were given in dosages ranging from 0,85 g/m2 to 7.42 g/m2 for a total of four weeks with a two week rest period between courses. Dose-limiting hematological toxicity was seen in heavily pretreated patients at a dose of 3.8 g/m2/week. All patients also developed reversible SGOT elevations. In patients with less prior therapy hematologic toxicity was not dose-limiting but hepatotoxicity, manifest by transient SGOT levels greater than 5 times baseline was seen at 7.42 g/m2/week even though only 3/6 patients could receive 4 consecutive weekly doses. At virtually all dose levels tested some patients developed anemia. Other toxicities, including alopecia, nausea, vomiting and reversible serum amylase elevations, were mild. Cumulative monthly doses achieved on this weekly schedule are significantly higher than a 48-hour infusion or daily times 3 or 5 schedule in adults and a daily times 3 schedule in children. Pharmacokinetic studies in eight patients indicate that the drug disappears from the plasma biphasically with a terminal t1/2 of 3.2 +0.9 hr. The total clearance was 288.7 + 85.0 ml/hr/kg and the volume of distribution (Vda) was 1.3 ± 0.4 1/kg. Pharmacokinetics were not dose-dependent from 3.8–7.4 g/m2 and no difference in pharmacokinetics was found in patients studied during the first and second treatments of a course. If Phase II trials of ICRF-187 are to be pursued on this schedule, appropriate doses would be 3.8 g/m2/week × 4 for heavily pretreated and 7.42 g/m2/week for “good risk” patients. Because of erratic hematologic toxicity in heavily pretreated patients, some might only tolerate three weekly doses. In good risk patients transaminitis was significant but reversible, thus, Phase II protocols should include dose escalation schemata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203545
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  • 102
    Electronic Resource
    Electronic Resource
    Phase I study and pharmacokinetics of caracemide (NSC-253272) administered as a short infusion (1987)
    Springer
    Investigational new drugs 5 (1987), S. 365-371 
    Details
    ISSN: 1573-0646
    Keywords: caracemide ; phase I ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A Phase I study of caracemide evaluating a short intravenous infusion repeated every 21 days is presented. Patients were entered at 85 mg/m2 with subsequent escalation levels of 170, 425, 595, and 795 mg/m2. Mild to moderate nausea and vomiting occurred at all dose levels. An apparent allergic reaction was observed at the 425 mg/m2 level. A “burning pain” originating in the mucosal areas of the head and neck, progressing to the chest and abdomen, was noted at the 425 mg/m2 level. Because of this observation, the infusion time was extended to 4 h. At the 795 mg/m2, this toxicity precluded completion of the 4 h infusion. Pharmacokinetic evaluation disclosed blood levels of 0.74–2.31 μg/ml at the 425 mg/m2 during the 0.5 h infusion. At the same dose for a 4 h infusion time, blood levels were 0.15–0.18 μg/ml. At 595 mg/m2 administered as a 4 h infusion, blood levels increased to 0.33 ± 0.14 μg/ml. The drug was cleared rapidly from the blood compartment with a half-life of 2.5 min and a total body clearance of 11.5 1/min/m2. No partial or complete response was observed. However, an advanced colon carcinoma patient experienced subjective pain relief with a decrease in carcinoembryonic antigen. The dose-limiting toxicity of caracemide using the 4 h infusion was an intolerable “burning pain” with a maximum tolerated dose of 795 mg/m2. Further characterization of this dose-limiting toxicity is required prior to further clinical evaluation of caracemide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169976
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  • 103
    Electronic Resource
    Electronic Resource
    Delayed elimination of a prazosin metabolite compared with kinetics of prazosin injected intravenously into rabbits (1987)
    Springer
    Bulletin of experimental biology and medicine 103 (1987), S. 85-87 
    Details
    ISSN: 1573-8221
    Keywords: prazosin ; prazosin metabolite ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00840147
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  • 104
    Electronic Resource
    Electronic Resource
    Correlation between the rate of ethanol elimination and psychophysiological differences in rats (1987)
    Springer
    Bulletin of experimental biology and medicine 103 (1987), S. 658-660 
    Details
    ISSN: 1573-8221
    Keywords: ethanol ; rats ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00841830
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  • 105
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of ethanol when injected intraperitoneally and intravenously into rats differing in initial alcohol motivation (1987)
    Springer
    Bulletin of experimental biology and medicine 104 (1987), S. 941-944 
    Details
    ISSN: 1573-8221
    Keywords: ethanol ; predisposition ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00841902
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  • 106
    Electronic Resource
    Electronic Resource
    Multicompartment models of cancer chemotherapy incorporating resistant cell populations (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 145-177 
    Details
    ISSN: 1573-8744
    Keywords: Chemotherapy ; mutation ; resistance ; compartmental analysis ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of antineoplastic drugs based on compartmental models are combined with deterministic exponential growth models of tumors containing drug-resistant and sensitive cells. Model predictions for single-drug therapy are compared with in vivodata obtained by other investigators for L1210 t-cell leukemia in mice treated with BCNU and AraC and for in vitrotreatment of L1210 with Ara-C. The model and data compare favorably in terms of rate of tumor growth and duration of drug action for both constant infusion and bolus delivery of the drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062341
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  • 107
    Electronic Resource
    Electronic Resource
    Protein binding of glycopeptide antibiotics with diverse physical-chemical properties in mouse, rat, and human serum (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 5-13 
    Details
    ISSN: 1573-8744
    Keywords: Structure-activity relationships ; pharmacokinetics ; protein binding ; glycopeptide antibiotics ; charge ; lipophilicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In previous studies of the pharmacokinetics and urinary excretion of nine glycopeptides with diverse isoelectric points (pI),as pIdecreases, the total systemic and renal clearance, urinary recovery, and volume of distribution decrease, whereas the half-life increases. With glycopeptides of similar pI,clearance decreases and half-life increases with increasing lipophilicity. The present study examines the serum protein binding of these glycopeptide antibiotics in mouse, rat, and human serum and calculates the previously reported pharmacokinetic parameters for these drugs based on unbound concentration. Increased negative charge and lipophilicity increase serum protein binding (90-fold, fu 83% to 0.96%), which decreases the renal clearance and total systemic clearance (90-fold, 16.4 to 0.18 ml/min/kg) of these drugs. Increased serum protein binding also decreases the volume of distribution of these compounds, but this change is relatively small (sixfold, 755 to 131 ml/kg) compared with the change in total systemic clearance causing an increase in elimination half-life (25-fold, 20 to 492 min). The results demonstrate that the large differences in the total systemic clearance and half-life of these glycopeptide antibiotics are primarily due to dramatic differences in serum protein binding and notto differences in the intrinsic elimination processes (enzymes or transport proteins). It appears that the same physical-chemical properties that govern the protein binding and pharmacokinetics of small organic molecules govern the disposition of these high-molecular weight glycopeptide antibiotics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062935
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  • 108
    Electronic Resource
    Electronic Resource
    A minimax approach to the single-point method of drug dosing (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 255-269 
    Details
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; singie-point dose prediction ; dosage ; minimax estimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The single-point dose prediction method is based on the observation that for drugs obeying single compartment elimination kinetics there is a nearly constant reciprocal relation between the plasma level at a fixed time following a single loading dose and the dose that is required to maintain the desired steady state plasma level of the drug. This paper describes an improved method for choosing a plasma sampling time and a proportionality constant. It applies to either drugs administered intravenously or to drugs whose rates of absorption from the site of administration are very rapid compared to their rates of elimination from the body. The sampling time and proportionality constant chosen are those that minimize the maximum relative deviation of the maintenance dose estimated by the single-point method from the dose that would be estimated if the individual's true elimination rate constant were known. The paper also supplies a method to determine the maximum error that may be introduced into the estimation of the maintenance dose by using the single-point method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066321
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  • 109
    Electronic Resource
    Electronic Resource
    Constant-rate infusion of nicotine and cotinine. I. A physiological pharmacokinetic analysis of the cotinine disposition, and effects on clearance and distribution in the rat (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 583-599 
    Details
    ISSN: 1573-8744
    Keywords: cotinine ; nicotine ; rat ; tissue distribution ; pharmacokinetics ; constant-rate infusion ; physiological model ; iv bolus ; osmotic minipump
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The tissue partition of cotinine was measured by a GC-MS method following a 6-day constant-rate input of nicotine and cotinine to male rats by means of an osmotic minipump. The tissue-to-blood partition coefficients of cotinine were calculated for adipose (0.08), brain (0.48), heart muscle (0.55), intestinal (0.53), hepatic (0.64), pulmonary (0.50), renal (0.99), and skeletal muscle tissue (0.51), following the cotinine infusion. When nicotine was infused the tissue partitioning of cotinine increased by a factor of 2.3–4.9, depending on the tissue sampled. Another group of animals were killed at timed intervals from 10 min to 30 hr, after having received a single intravenous bolus dose of 0.5 mg cotinine, and the washout of cotinine was traced in blood and tissues. A physiological model was used to simulate the disposition of cotinine. Generally, the model-predicted concentrations were consistent with those found experimentally. The fractional uptake of cotinine into various tissues was simulated. Blood, intestinal, and skeletal muscle tissues embodied more than 70% of the total body load of the drug. Clearance (Cl),volume of distribution (Vd),and the biological half-life (t1/2)were calculated both from the infusion study and by fitting a monoexponential model to the iv blood data of the rat. Significant differences were found in the apparent clearance calculated from the single iv bolus dose compared to the constant rate infusion. The volume of distribution was, however, consistent from both studies. The impact of a change in clearance was also simulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01068414
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  • 110
    Electronic Resource
    Electronic Resource
    A double-peak phenomenon in the pharmacokinetics of veralipride after oral administration: A double-site model for drug absorption (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 225-239 
    Details
    ISSN: 1573-8744
    Keywords: veralipride ; pharmacokinetics ; enterohepatic recycling ; double site of drug absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Equal doses of veralipride have been given to 12 healthy volunteers by three different administrations-intravenous infusion, oral solution, and oral capsule-in a randomized cross-over design. After the intake of the solution, but not after infusion or capsules, two maximum plasma concentrations have been observed and interpreted, according to a double-site model for drug absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066319
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  • 111
    Electronic Resource
    Electronic Resource
    Kinetics of ajmaline disposition and pharrnacologic response in beagle dogs (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 39-55 
    Details
    ISSN: 1573-8744
    Keywords: Ajmaline ; antiarrhythmic drug ; pharmacokinetics ; pharmacodynamics ; plasma protein binding ; combined pharmacokinetic-pharmacodynamic model ; ECG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pharmacokinetics and pharmacodynamics of ajmaline were studied in four healthy dogs after intravenous administration of the drug at the infusion rate of 1.0 mg/min for 45 min. Ajmaline exhibited a saturable binding to plasma protein. One kind of binding site was found in the range of observed drug concentrations and its binding capacity showed nearly threefold interindividual difference. The time course of ajmaline concentration in whole blood Cbcould be described by the two-compartment open model and the unbound concentration of ajmaline in plasma Pf wasestimated from Cbby using the hematocrit value and the parameters of plasma protein binding and erythrocyte partitioning. The pharmacologic responses to ajmaline were assessed by recording ECG, and the changes in PQ and QRS interval were studied in relation to ajmaline disposition. When ECG changes were related to the ajmaline concentration, a significant degree of hysteresis was observed. The relationship between the unbound drug concentration and the pharmacologic effect was analyzed by a combined pharmacokinetic-pharmacodynamic model, where the hypothetical effect compartment is connected to the Pfin the central compartment by a first-order process. This model allows estimation of the changes in PQ and QRS intervals after intravenous administration of ajmaline. By comparing the drug effect on PQ and QRS intervals, it was suggested that ajmaline distributes to the atrial and the ventricular tissue in a similar degree and causes a reduction in the conduction rate in both sites with similar activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062938
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  • 112
    Electronic Resource
    Electronic Resource
    The pharmacokinetics and pharmacodynamics of lignocaine and MEGX in healthy subjects (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 101-115 
    Details
    ISSN: 1573-8744
    Keywords: Lignocaine ; MEGX ; pharmacokinetics ; pharmacodynamics ; active metabolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Lignocaine clearance declines during continuous intravenous infustion in man and in vitrostudies suggest that this may partly be due to inhibition by MEGX, a metabolite of lignocaine, MEGX is pharmacologically active in animals, but this is not yet proven in man. This study examined the pharmacokinetics and pharmacodynamics of lignocaine and MEGX in eight healthy male volunteers given lignocaine HCl 120mg, MEGX HCl 120 mg, lignocaine HCl 120 mg+MEGX HCl 120 mg, and placebo, administered according to a randomized double-blind protocol. One-, two-, or three-compartment models were fitted to drug and metabolite blood concentration-time profiles and clearance, volume (V ss ), andhalf-life values were calculated and compared by paired t-test. Systolic time intervals and QTinterval were recorded and compared by repeated measures ANOVA. When administered in combination with MEGX, lignocaine clearance was significantly reduced from 58±18 to 48±13 L hr(su−1) (p 〈0.02). The V(inss) was unchanged and there was a trend toward an increase in terminal half-life. Lignocaine, MEGX, and the combination significantly reduced QTinterval up to 30 min after injection and this was maintained to 2 hr with the lignocaine and the combination. Transient side effects were experienced with all active treatments, but were most pronounced with the combination. Thus, lignocaine clearance was inhibited by MEGX, which was pharmacologically active in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062338
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  • 113
    Electronic Resource
    Electronic Resource
    Etintidine-propranolol interaction study in humans (1987)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 15 (1987), S. 557-568 
    Details
    ISSN: 1573-8744
    Keywords: etintidine ; propranolol ; 4-hydroxypropranolol ; interaction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Etintidine HCl is a potent H2 -blocker. The effect of clinical doses of etintidine on the disposition of a single oral dose of propranolol was investigated in 12 normal subjects. This was a double-blind, two-way crossover study. Each subject received etintidine (400 mg) or placebo twice a day with meals for 4 days on two occasions (separated by 4 days). On each occasion, the subjects were fasted overnight on Day 3 and were given an oral dose of Inderal® (40 mg propranolol hydrochloride) 30 min following the administration of the morning dose of etintidine or placebo on Day 4. Blood samples were collected prior to and up to 24 hr following the administration of propranolol. The plasma samples were analyzed for propranolol and 4-hydroxypropranolol by HPLC. Comparison of the pharmacokinetic parameters of propranolol between etintidine and the placebo groups indicates that etintidine significantly increased the AUC0−∞,values (573.5 vs. 146.4 ng·hr/ml, p=0.0001)and prolonged the elimination half-life (4.61 vs. 2.33 hr) of propranolol. Statistical evaluation of the pharmacokinetic parameters of 4-hydroxypropanolol indicates that etintidine also increased the AUC0−24 values (43.8 vs. 16.4 ng·hr/ml, p=0.0028) and prolonged the elimination half-life (4.87 vs. 1.97 hr) of 4-hydroxypropranolol. The data suggest that etintidine, like cimetidine, impaired the elimination of propranolol. Etintidine also protracted the elimination of 4-hydroxypropranolol, an active metabolite of propranolol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01068412
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  • 114
    Electronic Resource
    Electronic Resource
    Atrial natriuretic factor: a hormone secreted by the heart (1987)
    Springer
    Pharmacy world & science 9 (1987), S. 305-314 
    Details
    ISSN: 1573-739X
    Keywords: Atrial natriuretic factor ; Blood pressure ; Chemistry ; Diuresis ; Homeostasis ; Kidney ; Muscle, smooth ; Natriuresis ; Receptors, endogenous compounds ; Renin-angiotensin system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is now known that cardiac atria play an important role in blood pressure and volume regulation. Mechanical distension of the atria results in the release of a potent diuretic and natriuretic agent or agents termed the atrial natriuretic factor (ANF). Several structurally related forms of ANF exist in man and it is thought that these represent precursory forms of a single optimally active molecule and/or the presence of more than one form of active ANF. The chemical structure of ANF between different mammalian species is similar. ANF receptors have been identified in kidney, brain, vascular endothelial and smooth muscle cells, tracheal and bronchial smooth muscle and the adrenal glands of many mammalian species, including man. This would suggest that ANF influences blood pressure and volume homoeostasis by affecting any one of a number of biochemical or physiological mechanisms via different target tissues. ANF is now considered a potentially valuable therapeutic agent for the treatment of hypertension and congestive heart failure. Synthesis of potent receptor antagonists could be extremely useful in the treatment of various clinical situations which are produced or complicated by endogenously produced ANF, such as chronic orthostatic hypotension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01956510
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  • 115
    Electronic Resource
    Electronic Resource
    Dose-Proportional Absorption of Etretinate After Doses of 25, 50, 75, and 100 mg (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 420-424 
    Details
    ISSN: 1573-904X
    Keywords: etretinate ; pharmacokinetics ; dose proportionality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Twelve healthy male subjects received single oral doses of etretinate, ranging from 25 to 100 mg (1 to 4 × 25-mg capsules) in an open-label, four-way randomized crossover design. Plasma concentrations of etretinate and two active metabolites were determined by a specific high-performance liquid chromatographic (HPLC) method. Analysis of variance and orthogonal contrasts were used to assess dose proportionality. Mean (± %CV) maximum concentrations after 25- to 100-mg doses were 133 (50), 195 (33), 261 (53), and 446 (65) ng/ml, whereas AUC0−12 values were 581 (46), 1090 (39), 1500 (52), and 2440 (63) ng · hr/ml, respectively. The test for proportionality indicated that C max and AUC0−12 increased proportionally with an increase in dose (P 〉 0.05).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016494531044
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  • 116
    Electronic Resource
    Electronic Resource
    Dose-Dependent Pharmacokinetics of a New Oral Cephalosporin, Cefixime, in the Dog (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 33-37 
    Details
    ISSN: 1573-904X
    Keywords: oral cephalosporin ; cefixime ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cefixime (CL 284,635; FK 027) is a new third-generation oral cephalosporin. To study dose-dependent pharmacokinetics of cefixime in dogs, two balanced four-way crossover studies were conducted. In the first study, oral doses of 50, 100, and 200 mg/kg and an intravenous dose of 50 mg/kg cefixime were administered. In the second study, oral doses of 6.25, 12.5, and 25 mg/kg and an intravenous dose of 12.5 mg/kg cefixime were administered to the same dogs. A period of 1 month separated the two studies. When the two intravenous doses were compared (i.e., 12.5 and 50 mg/kg), a twofold increase in clearance and volume of distribution was observed after the higher dose. The oral systemic bioavailability in the dose range 6.25–50 mg/kg was 55%. It decreased to 44% at 100 mg/kg and 27% at 200 mg/kg. The average peak serum concentrations ranged from 15.8 µg/ml at 6.25 mg/kg to 119 µg/ml at 200 mg/kg. Within this concentration range, the fraction of free drug in serum (unbound to proteins) increased from 7 to 25%. This concentration-dependent protein binding was primarily responsible for changes in total clearance, volume of distribution, and bioavailability of the drug in dogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016473709720
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  • 117
    Electronic Resource
    Electronic Resource
    An Equation for the Systemic Availability of Drugs Undergoing Simultaneous Enterohepatic Cycling, First-Pass Metabolism, and Intestinal Elimination (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 195-199 
    Details
    ISSN: 1573-904X
    Keywords: enterohepatic recirculation ; pharmacokinetics ; bioavailability ; area under the curve ; bile ; hepatic extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A relationship between systemic availability and its determinants has been derived for a physiologically realistic model of drug disposition that includes enterohepatic cycling (EHC), gallbladder emptying (with an arbitrary time course), first-pass metabolism to noncycling metabolites, and fecal excretion. Systemic availability (F) has been shown to be determined by the fraction of the dose initially absorbed (f a*), the fraction of the drug excreted into the GI tract that is reabsorbed with each cycle (f a), the hepatic extraction ratio (E), and the fraction of extracted drug that is transported to the gallbladder for EHC (f g) according to the relationship F = f a*(1 −E/(1 − f a f g E) The implications of the above relationship are that (1) systemic availability is dependent on EHC, (2) values of F calculated to be greater than unity cannot be explained simply by the presence of EHC, (3) calculations of E based on the usual expression F = f a* (1 − E) are erroneous for drugs subject to EHC, and (4) a compound that has a high systemic availability and is subject to EHC is not necessarily inefficiently metabolized. The quantitative interrelationship of systemic availability and its determinants is illustrated using a contour plot. Slices through the surface are used to demonstrate that the presence of EHC changes the sensitivity of F to changes in E.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016447826075
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  • 118
    Electronic Resource
    Electronic Resource
    Application of Moment Analysis to Nonlinear Drug Disposition Described by the Michaelis–Menten Equation (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 59-61 
    Details
    ISSN: 1573-904X
    Keywords: mean residence time ; pharmacokinetics ; Michaelis–Menten elimination ; one-compartment model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An equation for the mean residence time (MRT) of drug in the body is derived for the system where drug is injected intravenously into a one-compartment model and eliminated by a single, capacity-limited process. This MRT is a complex function of dose, volume, V m, and K m but degenerates into the classical volume/clearance expression under limiting low-dose conditions (K m ≫ C 0). The equation was validated by comparison of the MRT obtained by direct calculation versus numerical area estimation for simulated data. The equation may be useful analytically in the estimation of the fundamental Michaelis–Menten parameters, V m and K m, from experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016486012446
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  • 119
    Electronic Resource
    Electronic Resource
    Effect of Amiodarone and Desethylamiodarone on the Pharmacokinetics of Antipyrine in the Rat (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 251-254 
    Details
    ISSN: 1573-904X
    Keywords: amiodarone ; antipyrine ; desethylamiodarone ; drug metabolism ; drug interactions ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of amiodarone on hepatic drug metabolism in vivo was examined in the rat using antipyrine as a model substrate. Pretreatment with oral amiodarone hydrochloride, 100 mg/kg/day, for 5 days resulted in a 19% reduction in antipyrine clearance and a 22% increase in half-life. The administration of single oral doses of amiodarone hydrochloride, 100 mg/kg, 1 or 5 hr prior to antipyrine administration had no significant effect on antipyrine pharmacokinetics. The administration of a single intravenous dose of amiodarone hydrochloride, 50 mg/kg, reduced antipyrine clearance by 32% and increased the half-life by 46%. The desethyl metabolite of amiodarone was also found to reduce antipyrine clearance (21%) after a single oral dose of 100 mg/kg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016468430618
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  • 120
    Electronic Resource
    Electronic Resource
    Computer-Aided Dosage Form Design. I. Methods for Defining a Long-Acting First-Order Delivery System of Maximum Formulating Flexibility (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 311-316 
    Details
    ISSN: 1573-904X
    Keywords: computer-designed formulation ; prolonged-action dosage forms ; drug delivery systems ; long-acting formulations ; theophylline delivery systems ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The method provides an a priori assessment of the maximum allowable flexibility in the rate of release from a prolonged-release formulation. The clinical pharmacokinetic parameters describing the drug candidate are employed to calculate the ranges of rate constants and doses required for the formulation to provide a selected therapeutic duration. For a given patient, there may be an infinite number of combinations of release rate constants and dose sizes which will maintain steady-state plasma drug concentrations within a desired range when the formulation is administered at the selected dosing interval. Computer simulations of steady-state plasma concentrations are employed to establish the ranges for all of the acceptable rate constants and doses for each member of a group. The entire group is then examined to define the range of release rate constants and doses which would provide a useful formulation for every member in the group. Literature values for theophylline clinical pharmacokinetics in children and adults have been employed to illustrate the application of this method. The method is unique in that it provides an entire range of release rates on which to gauge the feasibility for success.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016445220140
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    Pharmacokinetics of Gold Sodium Thiomalate in Rabbits (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 332-336 
    Details
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; gold ; rabbits ; intramuscular ; intravenous ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Male, New Zealand white rabbits (3.5–4.3 kg) received a single 2-mg/kg dose of gold sodium thiomalate (Myochrysine) via intramuscular (N = 4) and intravenous (N = 3) routes. Blood samples were drawn from the marginal ear vein for a period of 5–10 days. The concentration of gold in whole blood was determined using graphite furnace atomic absorption spectrophotometry. The blood concentration–time profiles obtained following both routes of administration were best described by a two-compartment open model with first-order absorption for the intramuscular route. Gold was absorbed rapidly with a mean (harmonic) absorption half-life of 9.0 min, with a peak concentration of 6.0 ± 1.0 µg/ml (N = 4). Blood concentrations declined in a biphasic manner; the mean α half-lives were 0.738 and 1.78 hr for the iv and im routes, respectively. The corresponding terminal (β) half-lives were 54.1 and 63.0 hr. The estimated volume of the central compartment (70 to 93 ml/kg) agreed closely with the rabbit blood volume. The mean ( ±SD) extent of the dose absorbed following intramuscular injection was 68.9 ± 12.4%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016453421958
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    Computer-Aided Dosage Form Design. II. Methods for Defining a Zero-Order Sustained-Release Delivery System of Maximum Formulating Flexibility (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 385-391 
    Details
    ISSN: 1573-904X
    Keywords: zero-order delivery ; drug delivery system ; sustained release ; computer simulation ; dosage form design ; theophylline ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Classical methods employing pharmacokinetic data to calculate zero-order release rates for sustained release products require that a constant-rate drug delivery system must have a duration which is exactly equal to the desired dosage interval. This traditional approach fails to establish the minimum acceptable duration and also fails to provide any flexibility in the formulation goal. While it does calculate one pair of duration and dose values, there are infinite pairs of values capable of maintaining the desired plasma concentrations using the selected dosing interval. In the current method, computer simulations are used to establish the boundary conditions within which any pair of duration and dose values will maintain the desired levels when administered on the chosen dosing interval. By comparing the boundary conditions for every subject in a group, a single set of conditions which would work for the entire group can be selected. These final limits represent the broadest specifications for zero-order drug delivery system design for that particular drug combined with the plasma concentration goals and the desired dosing interval. The method is illustrated using theophylline pharmacokinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016478127409
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  • 123
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    Pharmacokinetic drug interactions between digoxin and antiarrhythmic agents and calcium channel blocking agents: An appraisal of study methodology (1987)
    Springer
    Cardiovascular drugs and therapy 1 (1987), S. 183-189 
    Details
    ISSN: 1573-7241
    Keywords: drug interactions ; digoxin ; pharmacokinetics ; antiarrhythmic drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary While preliminary screening for interactions between new cardiovascular pharmacotherapeutic agents and digoxin can be efficiently and safely conducted in normal healthy volunteers, it is particularly important to detect and quantify drug interactions in patients with varying degrees of cardiac, hepatic and/or renal dysfunction. Much of the previously published literature provides only minimal data to guide clinical practice because of limitations of study design including sample size and measurement techniques. Important factors that determine the ability of a particular study design to detect a drug interaction with digoxin include the accuracy and precision of the assay method for serum digoxin concentrations, intrasubject and intersubject variability in serum digoxin concentration, and sample size. The format of the trial (chronic versus single digoxin dosing in cardiac patients; chronic verus single digoxin dosing in normal subjects) and the method of assessment of alterations in digoxin handling (formal determination of digoxin clearance, comparison of multiple or single digoxin measurements during various phases of trial) also impact greatly on the clinical relevance of such investigations. Guidelines for future studies of drug interactions with digoxin in cardiac patients are proposed with particular emphasis on laboratory methods; measurement techniques during baseline, placebo, and active drug phases; calculation of the statistical power of the study; time course of the trial; and assessment of the clinical significance of the findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02125472
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  • 124
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    Morphology of ultrahigh molecular weight polyethylene surface slid against steel (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 150 (1987), S. 189-192 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A morphological study was made to examine the friction and wear mechanisms of ultrahigh molecular weight polyethylene in air and water by means of transmission electron microscopy of a carbon replica film of a very thin layer of the polymer surface slid against a steel ball. Electron diffractions revealed that a molecular orientation with a typical fiber pattern was formed in the friction in air, while thin ribbon-like crystals with particular crystal orientations were formed in water in a way that the sliding took place on the crystallographic a - c plane, giving rise to a low friction coefficient of the polymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051500116
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  • 125
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    Degradation of polypropylene: Effect of stabilizers (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 150 (1987), S. 137-150 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde der relative Wirkungsgrad von fünf handelsüblichen Stabilisatoren bei Photooxidation und thermischer Alterung von Polypropylen (PP) anhand der Änderungen der mechanischen Eigenschaften untersucht. Es wurden Polypropylenproben mit unterschiedlichem Anteil an Cyasorb UV-531 hergestellt (bezeichnet als PC0.5-31, PC1-31, PC1.5-31 und PC2-31). Der Einfluß der Photooxidation auf das thermische Verhalten ist mit Hilfe der Differentialscanningkalorimetrie und durch thermogravimetrische Analysen untersucht worden. 2-Hydroxy-4-n-octyloxybenzophenon (2 Gew.-%) war am wirksamsten, Polypropylen, gegen Verfärbung und Brüchigkeit zu stabilisieren. Bei einer Probe mit 1% Stabilisatorzusatz fanden sich nach 32 h Bestrahlung noch 81% des ursprünglichen Wertes der Streckgrenze gegenüber 18% bei unstabilisiertem PP.
    Notes: The relative effectiveness of five commercially available stabilizers on the photooxidation and thermal ageing of polypropylene (PP) was investigated by following changes in mechanical properties. Samples of PP containing different percentages of Cyasorb UV-531 were prepared (designated as PC0.5-31, PC1-31, PC1.5-31, and PC2-31, respectively). The effect of photooxidation on thermal behaviour was investigated by differential scanning calorimetry and thermogravimetric analysis. 2-Hydroxy-4-n-octyloxy benzophenone (2% w/w) was most effective in stabilizing PP towards discolouration and brittleness. After 32 h irradiation, 81% retention in yield strength was observed in case of PC1-31 against 18% in case of PP.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051500111
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  • 126
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    Modified starch-natural rubber blend, I. Cyanoethylation of xanthated starch (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 153 (1987), S. 113-124 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Käufliche Weizenmehlstärke wurde unter Verwendung verschiedener Mengen Schwefelkohlenstoff und Acrylnitril xanthogeniert und cyanethyliert und dann zur Herstellung von modifizierten Stärke-Naturkautschuk-Masterbatches eingesetzt. Weiterhin wurden die Einflüsse untersucht, die die Gleichgewichte der Xanthogenierung und Cyanethylierung gegenseitig aufeinander ausüben. Die Ergebnisse werden auf der Basis definierter Wechselwirkungen zwischen der Xanthogenatgruppe und dem freien Acrylnitril erklärt. Hierbei führen sowohl sterische Faktoren als auch die höhere Elektrophilie des Acrylnitrils zum Zerfall der Xanthogenatgruppe. Daher kann die Cyanethylierung nur noch in einem geringeren Ausmaß erfolgen.
    Notes: Common wheat flour starch was subjected to xanthation followed by cyanoethylation at various levels of carbon disulfide and acrylonitrile to prepare modified starchnatural rubber masterbatches. Mutual influences of the extents of equilibrium xanthation and cyanoethylation on each other have been studied. The results have been explained on the basis of a definite interaction between xanthate group and free acrylonitrile in which both the steric factors and higher electrophilicity of acrylonitrile lead to the decomposition of xanthate groups and reduced the extent of cyanoethylation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051530108
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    Blends of polychloroprene and polyvinylchloridePresented in part at the International Conference on Rubber and Rubberlike Materials, November 6-8, 1986, Jamshedpur, India. (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 153 (1987), S. 153-163 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Polychloropren und Polyvinylchlorid wurden Blends in verschiedenen Zusammensetzungen hergestellt und ihre Eigenschaften bestimmt. Die Eigenschaften der Blends zeigen, daß sie Polychloropren in vielen Anwendungen ersetzen können.
    Notes: Blends of polychloroprene rubber and plasticized polyvinylchloride have been prepared in various compositions and their properties evaluated. The properties of the blends show that they can be used to replace polychloroprene in many applications.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051530111
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    Eine rheo-optische Apparatur für die Durchführung homogener, einfacher Dehnungen an Polymerschmelzen mit simultaner Aufzeichnung der Deformation, der mechanischen Spannung und der Doppelbrechung (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 153 (1987), S. 135-152 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The present paper describes a rheo-optical apparatus consisting of an elongational rheometer (with rotary clamps) and a device to measure birefringence. This equipment was designed to perform homogeneous deformations on polymer melts in the simple elongational mode. Elongational experiments were performed on polyisobutylene samples at room temperature using different strain rates (from \documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document} 0.01 s-1 to 1 s-1). In typical experiments homogeneous elongations up to λ ≈ 200 and stresses up to 2 · 106 Pa were achieved. The stress, the birefringence, and the deformation were obtained by measuring the force, the sample thickness, the optical retardation (the frequency of the sampling was 20 Hz) and the width of the sample (the frequency of the sampling was 3 Hz). It was found that the stress-optical coefficient was constant. The homogeneity of the deformations was carefully controlled because inhomogeneities cause serious errors in the measurements of elongational viscosity and birefringence.
    Notes: Es wird über eine rheo-optische Apparatur zur Verstreckung von Polymerschmelzen mit rotierenden Klemmen berichtet, die mit einer Doppelbrechungs-Meßeinrichtung ausgerüstet ist. Mit dieser Einrichtung können einfache Dehnungen an Polymerschmelzen bis zu hohen Verstreckgraden unter homogenen Bedingungen durchgeführt werden. Während des Deformationsvorganges können die Spannung, die Doppelbrechung und die Probendicke mit einer Meßrate von 20 Hz, sowie die Probenbreite mit ca. 3 Hz erfaßt werden.Wir haben Messungen an Polyisobutylen bei Raumtemperatur mit verschiedenen Dehngeschwindigkeiten (0,01 s-1 〈 \documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document} 〈 1 s-1) bis zu einem Verstreckgrad von λ ≈ 200 durchgeführt. Dabei wurden Spannungen bis zu 2 · 106 Pa erhalten. Das spannungsoptische Gesetz war bei homogener Versuchsführung stets erfüllt. Es wird gezeigt, daß ohne Kontrolle der Dehngeschwindigkeit und insbesondere bei inhomogener Dehung nicht nur Abweichungen vom spannungsoptischen Gesetz, sondern auch große Fehler bei der Spannungs- bzw. Viskositätsberechnung auftreten. Deshalb wurde großer Wert auf die Prüfung der Homogenität der Dehnung gelegt.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051530110
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    Verträglichkeit zwischen Methacrylat-homo- und Copolymeren (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 153 (1987), S. 187-195 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The miscibility of various polymethylmethacrylate (PMMA)/polybutylmethacrylate (PBMA)/poly(methylmethacrylate-co-butylmethacrylate)systems has been studied. PMMA and PBMA are immiscible. Methacrylic homopolymers and copolymers are immiscible, too. A one-phase mixture from PMMA and PBMA is only accessible by copolymerization.
    Notes: Die Mischbarkeit von verschiedenen Systemen aus Polymethylmethacrylat (PMMA), Polybutylmethacrylat (PBMA) und Poly(methylmethacrylat-co-butylmethacrylat) (P(MMA-co-BMA)) wurde untersucht. PMMA und PBMA sind miteinander nicht mischbar. Die untersuchten Homopolymeren und entsprechende Methacrylatcopolymere bilden ebenfalls heterogene Systeme. Einphasige Mischungen aus PMMA und PBMA sind nur über Copolymerisation erreichbar.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051530114
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    Ethylene insertion with soluble Ziegler catalysts. III. The system cp2TiMeCl/AlMe2Cl/13C2H4 studied by 13C-NMR spectroscopy. The time-development of chain propagation and oligomer distributionPart II cf. lit.1. (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 154 (1987), S. 1-21 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Hilfe der 13C-NMR-Spektroskopie wurde die Entwicklung der Oligomerenverteilung während der Polymerisation von 13C-angereichertem Ethylen mit dem löslichen Ziegler-Katalysatorsystem Cp2TiMeCl/AlMe2Cl verfolgt. Zuordnung und quantitative Auswertung aller Signale der verschiedenen wachsenden Ketten werden beschrieben. Die Geschwindigkeiten der Ethylen- und der Cp2 TiMeCl-Abnahme sowie die Bildungsgeschwindigkeit neuer Ketten konnten direkt aus den Spektren ermittelt werden. So läßt sich zum ersten Mal zeigen, daß die Konzentration der Ti-Propyl-und Ti-Pentylspezies in einen stationthen Zustand einlaufen. Dies ermbglicht, die Geschwindigkeitskonstanten der Ethyleninsertion in die Ti-Kohlenstoffbindung von Ti-Me, Ti-Pr und Ti-Pe zu ermitteln. Diese Ergebnisse fiihren zu einem detaillierten Ein-blick in den Ablauf der ersten Insertionsschritte und sind so eine Grundlage fur die mathematische Modellierung. Sie sind aufierdem ein weiterer unabhlngiger Beweis für die Giiltigkeit des dynamischen Modells des Mechanismus der Ethylenpolymerisation mit lbslichen Ziegler-Katalysatoren, nlmlich die Bildung der polymerisationsaktiven Spezies in zwei aufeinanderfolgenden sehr dynamischen Gleichgewichtsreaktionen.
    Notes: The development of the oligomer distribution during the polymerization of 13C-enriched ethylene by the soluble Ziegler catalyst system Cp2 TiMeCl/AlMe2Cl was followed by 13C-NMR spectroscopy. The assignment of the signals from the growing chains is described in full. It is shown that the rate of consumption of ethylene and Cp2 TiMeCl and the rate of formation of new chains can be monitored directly from the spectra. The concentrations of Ti-propyl and Ti-pentyl species during the polymerization were followed spectroscopically; both attain a steady state concentration. The relative rates were determined for the insertion of ethylene in the Ti-carbon bond of Ti-Me, Ti-Pr and Ti-Pe. These results give a detailed insight into the way that the oligomer distribution develops and provide a basis for its computer simulation. They also provide an independent proof that the dynamic model for the mechanism of ethylene polymerization with soluble Ziegler catalysts of the type Cp2 TiRCl/AlRnClm is correct.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051540101
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    Effects of reaction conditions on bromination of atactic poly(propylene) (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 154 (1987), S. 99-110 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß verschiedener Reaktionsbedingungen auf die Bromierung von ataktischem Poly(propylen) (APP) in Tetrachlorkohlenstofflösung wurde untersucht. Mit zunehmender Reaktionszeit steigt der Bromierungsgrad. Auch mit steigender Verdünnung der APP-Lösung nimmt die Bromierungsgeschwindigkeit zu, welche bezüglich der APP-Konzentration die Ordnung 0,66 hat. Dies wird erklärt durch die anfängliche Substitution eines Wasserstoffs am tertiären Kohlenstoffatom. Die folgende H-Abstraktion an den benachbaren sekundären und primären Kohlenstoffatomen ist erleichtert. Die scheinbare Aktivierungsenergie wurde zu 11,9 kcal/mol bestimmt. Die Bromierungsgeschwindigkeit steigt bis zu einem APP : Br2-Molverhältnis von 1 : 1 an, darüber hinaus wird die Geschwindigkeit unabhängig vom Molverhältnis. Die Bromierung scheint folgendermaßen zu verlaufen: Nach anfänglicher Substitution eines tertiären H-Atoms durch freie Bromradikale werden nach und nach auchdie sekundäen und primären H-Atome durch weitergehende Substitution oder durch Addition nach einem Eliminierungsschritt ersetzt. Das IR-Spektrum bestätigt die Anwesenheit von Brom in den Proben.
    Notes: Effects of various reaction conditions on bromination of atactic poly(propylene) (APP) in carbon tetrachloride solution were studied. It was found that with the increase of the reaction time the extent of bromination increases. Also with an increased dilution of APP the rate of bromination increased following a bromination order of 0.66 with respect to APP concentration. This has been ascribed to initial replacement of the hydrogen at the tertiary carbon atoms followed by enhanced ease of abstraction from the neighbouring secondary and primary carbon atoms. The apparent activation energy was found to be 11.9 kcal/mol. The rate of bromination increases with an increase of the APP: Br2 molar ratio up to 1 : 1, beyond which the rate becomes independent of this ratio. Mechanism of bromination appears to be an initial substitution of tertiary H-atoms by bromine radicals followed subsequently by replacement of secondary and primary H-atoms via either progressive substitution or elimination-addition. IR spectra confirm the presence of bromine in the samples.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051540107
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    A high molecular-weight sequential polypeptide, poly(leucyl-γ-ethyl glutamyl-alanyl-alanyl) (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 5-8 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260104
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    Determination of thermodynamic functions from scanning calorimetry data (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 213-229 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a theoretical basis and new methods for the determination of thermodynamic functions from scanning calorimetry data. A thermodynamic state is defined here as an ensemble of microstates in the system, and it can be defined only through assumptions of its heat capacity function and the two integral constants. With these assumptions, scanning calorimetry data can be analyzed using the single or double (or multi-) deconvolution presented here. New equations to calculate the van't Hoff enthalpy function and the calorimetric enthalpy function are presented. We prove that the agreement of these two functions is a necessary and sufficient factor for the condition that the system can be described with the assumed two-state model.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260205
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  • 134
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    Poly[d(A-T)-Cs+] conformations studied by IR spectroscopy (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 251-260 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Infrared absorption and ir linear dichroism measurements have been performed on poly[d(A-T)-Cs+] films at various relative humidities. At high relative humidity, samples are in a B form; at low relative humidity, in a C form. The B → C conformational transition is shown to be a noncooperative one corresponding to a gradual evolution of the backbone geometry of the polynucleotide within the B family. the C-form-type spectrum is characteristic of an alternated phosphodiester chain with a dinucleotidic repeat unit.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260207
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    Masthead (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260301
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  • 136
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    Reversal of the long-wavelength CD band of poly(dI-dC) · poly(dI-dC) on specific interaction with the 53-58 peptide fragment of the lac repressor (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 329-332 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260302
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  • 137
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    Molecular mechanical studies on left- and right-handed B-DNA (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 403-414 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular mechanical simulations on base-paired deoxyhexanucleoside phosphates, (dAdT)3 · (dAdT)3, (dTdA)3 · (dTdA)3, (dGdC)3 · (dGdC)3, and (dCdG)3 · (dCdG)3, have been carried out to assess their energetic stabilities in left- and right-handed forms. These hexamers have also been simulated with alternating sugar-puckering profiles with the combinations (purine : C2′-endo-pyrimidine : C3′-endo) and (purine : C3′-endo-pyrimidine C2′-endo). The right-handed models have been found to be the energetically most stable structures and the left-handed structures are significantly destabilized. This instability has been rationalized in terms of competition between stabilizing stacking interactions on one hand, and distortions in the bond angles and torsion angles in the sugar-phosphate backbone on the other.
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    Loop formation in polynucleotide chains. II. Flexibility of the anticodon loop of tRNAPhePresented in part at the Biophysical Society Meeting, San Antonio, Texas, February 1984. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 415-438 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flexibility of hairpin loops containing n bases (residues) has been examined using a theoretical model [N. L. Marky and W. K. Olson (1982), Biopolymers, 21, 2329-2344] of oligonucleotide loop closure. The study is based on correlated probabilities of chain separation and terminal residue orientation as outlined previously. The probabilities are calculated using standard statistical mechanical methods as functions of local conformational changes of the chain backbone. Our results for an RNA chain of 9 residues suggest that the anticodon loop is a dynamic structure capable of assuming a variety of different spatial conformations. Free energy values related to the various conformations span a narrow range of values (2-4 kcal/mole) and compare well with experimental observations in aqueous solution. Conformational transitions between the loop conformations are within less than 0.5 kcal/mole in free energy. The different spatial loop conformations and the likely pathways between them may have potential relevance to the molecular translation of the genetic code.
    Additional Material: 16 Ill.
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  • 139
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    Structural models for the N- and C-terminal telopeptide regions of interstitial collagens (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 463-480 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Secondary-structure prediction has been used to investigate the conformation of the N- and C-terminal telopeptides for type I and type III collagen. The three predictive methods (Chou and Fasman, Robson and co-workers, Lim) indicate mainly aperiodic conformations. A common structural motif is provided by the positioning of β-turns, particularly in the vicinity of the residue sites involved in intermolecular cross-links. An alternative model to that of Helseth et al [(1979) Biopolymers 18, 3005-3014] for the secondary structure of the N-terminal telopeptide of type I collagen is proposed. The general features of these two contrasting structures have been surveyed by model-building techniques employing molecular graphics and energy minimization. The role of the telopeptide component in the structural design of the biomaterial collagen is assessed. Notably, the alternative model clearly serves to demonstrate the compatibility of current cross-linking evidence with the quasi-hexagonal model for the packing of molecules within a collagen fibril.
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    URL: http://dx.doi.org/10.1002/bip.360260403
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  • 140
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    Conformation of the oligonucleotide d(AAAAAATTTTTT)2 by two-dimensional nuclear overhauser effect spectroscopy and its relevance to poly(dA) · poly(dT) (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 525-536 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational analysis from the pattern and intensities of cross-peaks in the two-dimensional nuclear Overhauser effect proton nmr spectra of the homopolymer, poly(dA) · poly(dT), and the analogous oligomer, d(AAAAAATTTTTT)2, indicate that they both exist in the B-conformation. The conformation of the ApT/TpA junction in the oligomer is significantly different from the rest of the base pairs.
    Additional Material: 8 Ill.
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  • 141
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    Masthead (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260501
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  • 142
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    The mobility of polyions in gel electrophoresis (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 609-611 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260503
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  • 143
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    Masthead (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260101
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  • 144
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    Editor's note (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. iii 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260102
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  • 145
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    Radius of the elastic rod model of a polyelectrolyte (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1-3 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 146
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    The influence of calcium ions on fibrin polymerization (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 27-43 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of calcium ions on the polymerization induced in fibrinogen solutions by thrombin and by Reptilase has been investigated by meansof static and dynamic light scattering in combination with measurements of the release of the fibrinopeptide A. The calcium concentration was varied in the range between 0.3 and 103 calcium ions per fibrinogen molecule. The enzyme concentration was chosen sufficiently low so that it was possible to make quantitative observations as a function of time, in particular, beforethe onset of gelation. Likewise, the influence of calcium ions on the enzymatically induced polymerization of fragment X was studied. The results indicate that there are at least three mechanisms by which calcium can influence the evolution of the polymer system on the path to gelation and clotting. Which mechanism dominates depends upon the calcium concentration.
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    URL: http://dx.doi.org/10.1002/bip.360260107
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    Local sequence patterns of hydrophobicity and solvent accessibility in soluble globular proteins (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 17-26 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We examined the variation in the solvent accessibility and hydrophobicity of the amino acids along the sequences of 58 soluble globular proteins with known tertiary structure. We found that there is a significant tendency for the accessibilities to run in clusters along the sequence but that the hydrophobicities are distributed without such nonrandom clusters. Theseresults suggest severe limitations on the power of sequence analysis tools that use average hydrophobicity scores of overlapping subsequences to predict accessibility.
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  • 148
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    On the CD helix band for long helical polymers (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 109-119 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD helix bands for infinitely long helical polymers are shown tobe composed of two parts: a derivative-shaped band plus an ordinary Gaussian-like band. The derivative-shaped band results from the zero-order term of an expansion while the Gaussian-like band results from the first-order expansion term. However, the intensities of the two bands are shown to be of the same order of magnitude. They are both linear in the coulombic coupling of transition charge densities for polymer transitions. The sum yields a skewed derivative-shaped band. The shapes of net CD helix bands are shown to not depend on the approximations used for averaging over orientations if the usual systems, such as polypeptides and polynucleotides, are considered in their long-wave-length spectral regions.
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    URL: http://dx.doi.org/10.1002/bip.360260112
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  • 149
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    Prediction of the folding of short polypeptide segments by uniform conformational sampling (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 137-168 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure, CONGEN, for uniformly sampling the conformational spaceof short polypeptide segments in proteins has been implemented. Because thetime required for this sampling grows exponentially with the number of residues, parameters are introduced to limit the conformational space that has to be explored. This is done by the use of the empirical energy function ofCHARMM [B. R. Brooks, R. E. Bruccoleri, B. D. Olafson, D. J. States, S. Swaminathan and M. Karplus (1983) J. Comput. Chem. 4, 187-217] and truncating the search when conformations of grossly unfavorable energy are sampled. Tests are made to determine control parameters that optimize the search without excluding important configurations. When applied to known protein structures, the resulting procedure is generally capable of generating conformations where the lowest energy conformation matches the known structure within a rms deviation of 1 Å.
    Additional Material: 9 Ill.
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  • 150
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    Number of binding sites of DNA and polynucleotides with tris(2,2′-bipyridyl)ruthenium(II) cationsDedicated to professor arther charesby on the occasion of his 70th birthday. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 189-201 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of tris(2,2′-bipyridyl)ruthenium(II) cations [Ru(bpy)2+3] with single- and double-stranded (ss and ds) DNA, and the polynucleotides poly(A), poly(C), poly(G), poly(I), poly(I) · poly(C), and poly(U), was studied in aqueous solution. Steady-state electrical conductivity measurements with the polynucleotides, ssDNA, and dsDNA reveal that approximately three nucleotides offer one binding site. This may be compared with the ratio [nucleotide]/[Mg2+] of 2.4 : 1 for dsDNA. After laser excitation (353 nm), the luminescence of Ru(bpy)2+3 bound to nucleic acids shows two decay components. The contribution of the fast component, which is interpreted as resulting from quenching processes of the absorbed ruthenium complex, exhibits a maximum with increasing [nucleotide]/[Ru(bpy)2+3] at a ratio of about three to one. Bound Ru(bpy)2+3 can be released from the strand by addition of NaClO4 [half-concentration: 2.5 and ≤ 10 mM for poly(U) and dsDNA, respectively].
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260203
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    Predicting antibody hypervariable loop conformation. I. Ensembles of random conformations for ringlike structures (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 2053-2085 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One approach to finding the conformation of minimum energy for a complicated molecule is to perform energy minimization, perhaps coupled to more exhaustive search procedures such as dynamics or Monte Carlo sampling, from many starting conformation. Where there are geometric constraints on the conformations, as in a ring molecule, or a variable loop starting and ending in known constant regions of one of a series of homologous proteins, rapidly generating many such starting conformations, all satisfying the constraints, has been a problem in the past. We have devised an algorithm, which we call random tweak, which performs this task in the context of a torsional description of a molecule, and have used it to model the backbones of the six CDRs (complementarity determining regions) of the immunoglobulin MCPC603. These range in size from 5 to 19 residues, and have from 8 to 36 variable dihedral angles. Ensembles of 100 properly closed backbone structures for each CDR were generated under several conditions of van der Waals screening internally and against the rest of the molecule, and ensembles of 1000 were generated for selected CDRs. These structure “libraries” reveal how the geometry at the base of a CDR and the topography of the surrounding protein surface restrict the region of space that a given CDR can occupy. In accord with simple notions of chain molecule statistics, the more highly extended a CDR at its base, the more similar the possible structures and the fewer that are necessary to span the conformational space. Energy minimization and molecular dynamics studies (reported elsewhere) using these libraries to furnish starting conformations show that, as the number of residues in a CDR goes from five to nine, the number of randomly generated structures necessary to ensure that low-lying energetic minima, such as the native conformation, will be found several times goes from a few tens to a few hundred. Some of the spatial features of an ensemble of random conformations are implicit in the histogram of the rms atomic displacements calculated for all the pairs in the ensemble. The random tweak method is carried out by setting each dihederal angle on the main chain of the variable fragment to a random value, then using an iterated linearized Lagrange multiplier technique to enforce the geometric constraints with the minimal conformational perturbation. The time required for the algorithm is linear in fragment length, and the resulting ability of the method to handle large loops makes it especially applicable to the modeling of homologous proteins. In most cases, hundreds of acceptable structures could be generated in a few hours on a VAX 11/780. Where van der Waals screening against fixed atoms need not be performed, as for isolated ring molecules, generation times go down by an order of magnitude or more.
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    URL: http://dx.doi.org/10.1002/bip.360261207
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  • 152
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    Dynamic light-scattering study of semiflexible polymers: Collagen (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1717-1729 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dynamic light-scattering measurements were carried out for collagen in acetate buffer (pH 4.8) extracted from lathyritic ratskin. The correlation functions were analyzed in terms of the semiflexibility of collagen molecules. The experimental Γ/K2 vs K2 relationship was compared with the theoretical one based on formulation including anisotropy in translational diffusion, chain flexibility, and the hydrodynamic interaction; Γ is the average decay rate and K is the magnitude of the momentum transfer vector. By using the model parameters evaluated from the Γ/K2 vs K2 relationship, a good agreement was obtained between profiles of theoretical and experimental correlation functions over the entire delay times. Detailed examinations of the dynamic light-scattering spectrum permitted us to conclude that a set of the contour length L of 300 nm and the Kuhn length γ-1 of 340 nm are much more probable than other sets of L and γ-1 that equally explain static quantities such as the radius of gyration. The results show that collagen molecules are well characterized by a wormlike chain model.
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    URL: http://dx.doi.org/10.1002/bip.360261006
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    Dynamic properties of oxy- and carbonmonoxyhemoglobin probed by optical spectroscopy in the temperature range of 300-20 K (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1769-1779 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the absorption bands of oxy- and carbonmonoxyhemoglobin in the wavelength range of 650-350 nm (visible and Soret bands) and in the temperature range of 300-20 K. The spectra in the whole temperature range have been successfully deconvoluted in terms of gaussian components. The analysis of the temperature dependence of the first and second moment of the bands enables us to compare dynamic properties of the heme group in oxy- and carbonmonoxyhemoglobin. The results of the analysis indicate that the “mean-effective” frequency of the nuclear motion coupled to the electronic transition responsible for the visible bands is higher in carbonmonoxy- than in oxyhemoglobin. The possible functional relevance of this finding is discussed.
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    URL: http://dx.doi.org/10.1002/bip.360261009
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  • 154
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    A predictive model of enzymatic cleavage of nucleic acids (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1789-1807 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new static model of enzymatic cleavage of polymeric substrates such as nucleic acids has been derived. The model is compared to that elaborated by Tanford and to experimental data. In predicting the fragment distribution for a restriction enzyme digestion of a circular substrate, the model is superior to that of Tanford.
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    URL: http://dx.doi.org/10.1002/bip.360261011
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  • 155
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    A mixed β-turn and β-sheet structure for bovine tooth enamel amelogenin: Raman spectroscopic evidence (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1809-1813 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360261012
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  • 156
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    Theoretical conformational analysis of a μ-selective cyclic opioid peptide analog (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1431-1444 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The allowed conformations of the μ-receptor-selective cyclic opioid peptide analog were determined using a grid search through the entire conformational space. Energy minimization of the 13-membered ring structure lacking the exocyclic Tyr1 residue and the Phe3 side chain using the molecular mechanics program Maximin resulted in only four low-energy conformations. These four ring structures served as templates for a further energy minimization study with the Tyr1 residue and Phe3 side chain added to the molecule. The results indicated that the Tyr1 and Phe3 side chains enjoy considerable orientational freedom, but nevertheless, only a limited number of low-energy side-chain configurations were found. The obtained low-energy conformers are discussed in relation to various proposed models of the bioactive conformation of enkephalins and morphiceptin.
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    URL: http://dx.doi.org/10.1002/bip.360260817
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    Solvent effect on the stability of mannobiose conformersPart X: Theoretical Studies on the Conformation of Saccharides. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1499-1508 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational equilibria of seven methyl β-D-mannobioside conformers have been studied theoretically in five solvents. The structure of each individual conformer has been refined by the PCILO quantum-chemical method from the seven distinct low-energy regions determined from (Φ, Ψ) maps calculated by a potential function method. The stability of the conformers in dilute solution has been evaluated by using a method that consists of electrostatic, dispersion, and cavity terms. The calculated abundance of conformers depends on the solvent and results indicate that the preponderant conformer in the solution may not be the one adopted by mannobiose in the crystalline form. Based on the determined abundance of conformers, thermodynamically averaged nmr parameters, dipole moment, and linkage rotation have been calculated. The solvation behavior of methyl β-D-mannobioside is compared to those previously estimated for cellobiose and maltose.
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  • 158
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    The thermodynamic parameters of the interaction of concanavalin A with glycosyl-free liposomes: A microcalorimetric study (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1509-1526 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nonspecific interaction of the mitogenic lectin Concanavalin A (Con A) with glycosyl-free liposomes of various composition has been investigated by microcalorimetric titration measurements. The results obtained show the following features of main interest: (1) the affinity constants (Ka) of the interaction of Con A with liposomal bilayers are in the order of magnitude 105-106M-1. The reaction enthalpies (ΔH) are positive, and small (approximately 0.1 KJ mol-1 lipid), compared to the free energy terms (-ΔG = 30-40 KJ mol-1 lipid). All lectin-lipid interactions are strongly entropy-controlled (ΔH/TΔS 〈 1.0). These thermodynamic features are characteristic for hydrophobic interaction processes. (2) The liposomal head-group charge does not significantly affect the lipid-affinity of Con A. Electrostatic forces thus appear to play a minor role in lectin-lipid interactions. (3) The lipid affinity of Con A is sensitive to the fluidity of the liposomal bilayers, increasing with increasing fluidity. Below the gel to liquid-crystal phase transition temperature, the lectin binding to liposomal bilayers is inhibited. (4) The binding isotherms, corresponding to the interaction of Con A with liposomes, composed of tightly packed, saturated phospholipids, exhibit pronounced positive cooperativity. This phenomenon is absent in the binding curves, corresponding to the interaction of Con A with more fluid liposomal bilayers. (5) The Con A specific inhibitor α-D-methylmannopyranoside (50 mM) drastically increases the molar reaction enthalpy. The Ka term is significantly reduced in presence of the inhibitor sugar. Urea induces analogous changes in the thermodynamic parameters of the lectin-lipid interaction. The effects of α-D-methylmannopyranoside are thus not Con A specific, but are attributable to solvent effects. (6) It was shown that the binding of one Con A molecule affects a large number (approximately 1000) of phospholipid molecules in the liposomal bilayer. (7) The affinity constants (Ka) of the interaction of Con A with glycosyl-free lipids are smaller by a factor of approximately 10, compared to the Ka terms, reported for Con A binding to biological membranes. The presence of glycosidic receptor groups thus controls the specificity of lectin-membrane interactions, whereas the nonspecific lectin-lipid interactions appear to represent the main driving force for the strong attachment of the lectin to membrane surfaces.
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    URL: http://dx.doi.org/10.1002/bip.360260906
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    Calculating thermodynamic data for transitions of any molecularity from equilibrium melting curves (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1601-1620 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper, we derive the general forms of the equations required to extract thermodynamic data from equilibrium transition curves on oligomeric and polymeric nucleic acids of any molecularity. Significantly, since the equations and protocols are general, they also can be used to characterize thermodynamically equilibrium processes in systems other than nucleic acids. We briefly review how the reduced forms of the general equations have been used by many investigators to evaluate mono- and bimolecular transitions, and then explain how these equations can be generalized to calculate thermodynamic parameters from common experimental observables for transitions of higher molecularities. We emphasize the strengths and weaknesses of each method of data analysis so that investigators can select the approach most appropriate for their experimental circumstances. We also describe how to analyze calorimetric heat capacity curves and noncalorimetric differentiated melting curves so as to extract both model-independent and model-dependent thermodynamic data for transitions of any molecularity. The general equations and methods of analysis described in this paper should be of particular interest to laboratories that currently are investigating association and dissociation processes in nucleic acids that exhibit molecularities greater than two.
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    URL: http://dx.doi.org/10.1002/bip.360260911
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    Conformational studies of diastereomeric cyclic enkephalins by 1H-NMR and computer simulations (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1573-1586 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report the solid-phase synthesis and conformational analysis of a 14-membered, cyclic enkephalin analog, H—Tyr—c[—D—A2bu—Gly—Phe—D—Leu—] (where A2bu represents α,γ-diaminobutyric acid). The results from the guinea pig ileum (GPI) and mouse vas deferens (MVD) assays show that the analog, though active, has little selectivity for the μ or δ opioid receptors. Conformational analysis is carried out using 1H-nmr and computer simulations, including molecular dynamics and energy minimizations. The results obtained here are compared with the findings of our studies carried out on the μ-receptor-selective diastereomer, H—Tyr—c[—D—A2bu—Gly—Phe—Leu—] [N. Mammi, M. Hassan, and M. Goodman (1985) J. Am. Chem. Soc. 107, 4008-4013]. This comparison allows for insight into the regiospecificity of these cyclic enkephalin analogs.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260909
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    Characterization of the interactions of an amino-terminal fibronectin fragment with the native molecule: Implications for polymerization of fibronectinThe results of this study were presented in abstract form at the 1986 meeting of the American Society of Biological Chemists in Washington, D. C. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 2087-2098 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plasma fibronectin is a 450-kD glycoprotein composed of two similar subunits connected by interchain disulfide bridges that may fold over in solution, allowing the amino terminus of each chain to bind the carboxyl terminus of the same subunit or a different subunit, thereby allowing polymerization. In order to study the characteristics of the fold-over interaction, the interaction between the amino terminal 29-kD fragment of fibronectin with native fibronectin has been studied in detail. One 29-kD molecule bound per fibronectin subunit, the apparent equilibrium dissociation constant was 40 nM, and the half-times for association and dissociation at 22°C were, respectively, 16 h and 23 days. Complexation could be inhibited by high concentrations of salt, but not by 8M urea. Amino terminal 20-kD and carboxyl terminal 8-kD subfragments of the 29-kD fragment also bound fibronectin and the activity was dependent on the integrity of the type 1 loop structures. The kinetics of the interaction of 29-kD fragment with fibronectin were unaffected by the presence of ligands, but were affected by detergents such as sodium dodecyl sulfate or deoxycholate, which enhanced the rate of interaction over 100-fold or 6-fold, respectively. Therefore, the interaction of fibronectin with ionic cell membrane components such as deoxycholate in vivo may trigger polymerization.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360261208
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    Editor's note (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. Si 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260002
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  • 163
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    Peptidomimetics: Synthesis, spectroscopy, and computer simulations (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S25 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, spectroscopy, and computer simulations are used in an integrated approach to elucidate secondary structure of oligopeptides. Three lactam-bridge peptides were synthesized and examined. One of these model compounds was shown to prefer a β-turn conformation, as indicated by spectroscopy (CD and nmr), and by computer simulations of minimum potential energy and of molecular dynamics. Partial retro-inverso cyclic analogs of enkephalin were also synthesized and investigated. Biological activity studies of the analogs indicated that the Gly3 carbonyl group and the side-chain orientation of the L-Leu5 residue are important. Hydrogen-bonding patterns for the three analogs are described in terms of the spectroscopic evidence correlated to the molecular dynamics simulations.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260007
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    On the multiple-minima problem in the conformational analysis of polypeptides. I. Backbone degrees of freedom for a perturbed α-helixThis article is dedicated to Ephraim Katchalski-Katzir on the occasion of his 70th birthday. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S33 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The multiple-minima problem is the most formidable in the conformational analysis of polypeptides. Several approaches have been developed to surmount this problem, and we present an additional one here that may possibly be extendable to very large polypeptides. In this new approach, designated the Self-Consistent Electric Field (SCEF) method, we calculate the electric field, due to the whole molecule, at each CO and NH group of the peptide units, and also in the middle of the C′N peptide bonds, for an arbitrary starting conformation. It is assumed that the native conformation has approximately optimal orientations of its group dipoles in the electric field. The direction of the electric field with respect to the CO and NH bond dipole moments provides information as to which peptide units are the worst oriented. We then compute the changes in the backbone dihedral angles φ and ψ required to align the most unfavorably oriented peptide-unit dipole moments along the electric field. After carrying out such alignment of dipoles, a complete potential energy function is used in a minimization procedure to locate the nearest local minimum. The SCEF and energy-minimization procedures are then applied iteratively to try to locate the global minimum. The effectiveness of this method is illustrated by computations on very different starting conformations of terminally blocked 19-residue chains of poly(L-alanine), for which the global minimum is judged to be the right-handed α-helix.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260008
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    Raman and normal-mode studies of the extended-helix conformation in polypeptide chainsThis is paper number 36 in a series on vibrational analysis of peptides, polypeptides, and proteins, of which Ref. 23 is paper number 35. (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S99 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nature of the local main-chain conformation of polypeptides with charged side chains has been the subject of considerable discussion since Tiffany and Krimm first proposed [(1968) Biopolymers 6, 1379-1381] that, rather than being random, the chain is locally relatively regular, with conformations similar to that of a left-handed threefold helix. Such structures, referred to as “extended-helix” (EH) conformations, have now been studied in a charged poly(L-glutamic acid) system by a combination of Raman spectroscopy and normal-mode analysis. Calculations were done for EH conformations with 3.0 and 2.4 residues/turn, using force fields refined for α-helix, 31-helix, and β-sheet structures. Together with previous results on the α-helix and β-sheet forms, an interesting new correlation emerged: the frequency of the CαC stretch skeletal mode, usually found in the 900-1000 cm-1 region of the Raman spectrum, is essentially linearly correlated with the value of the φ angle. Applying this relationship to the observed frequencies of the α-helix and β-sheet forms of poly(L-glutamic acid), we find that an observed sharp band in the spectrum of crystals of the calcium salt of poly(L-glutamic acid) (which is close to the frequency observed for the charged form in solution) corresponds to an EH conformation very close to that predicted from energy calculations. These studies thus provide very strong support for our proposal that charged polypeptide chains are not random but adopt local conformations of the EH type.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260011
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  • 166
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    Noise as a source of information about dynamical properties of biological macromolecules (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S161 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The time course of a noise signal is not completely random, since it is coupled to the characteristic dynamical behavior of the physical system that produces the noise. The statistical properties of the noise may thus be very informative about the properties of the noise-generating system. The use of the autocorrelation function, of modified autocorrelation functions that show directionality with respect to the time axis, and of probability density-distribution functions of intervals in noise traces are discussed. Thus, by labeling specific points on polymer chain molecules by suitable chormophores between which excitation energy transfer may occur and by analyzing the autocorrelation function of the fluctuations in the emitted fluorescence under steady illumination, one may characterize the internal dynamics of the polymer molecules. It is also shown that the presence or absence of time directionality in noise traces, as tested with the help of some of the above-mentioned statistical functions, may demonstrate whether the noise-generating system is at thermodynamic equilibrium or whether irreversible processes are coupled to the dynamic changes that produce the noise signals.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260015
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  • 167
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    Salting-out adsorption techniques for protein purification (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S193 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Salt-promoted adsorption of proteins occurs on hydrophobic gels, on immobilized metal ions e.g., Zn2+, Co2+, Ni2+, Cu2+, and on newly described absorbents provisionally called “thiophilic gels.” The latter gels are characterized by the ligand structure —SO2—CH2—CH2—S—R. In a simple form (R = —CH2—CH2—OH) the “T-gel” is extremely useful for rapid isolation of immunoglobulins from complex mixtures. When R is rich in π-electrons the thiophilic affinity will be superimposed by charge-transfer coupling with hitherto unknown counterligands in interacting proteins. The use of tandem and cascade processes for protein fractionation according to several more or less independent separation parameters is briefly demonstrated.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260017
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  • 168
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    The emulsan polymer: Perspectives on a microbial capsule as an industrial product (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. S223 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Microbial polysaccharides have become significant industrial products in recent years, primarily because of their high molecular weight and unique rheological properties. More recently, a new class of microbial biopolymer has been developed - namely, the exopolysaccharide bioemulsifiers. The best studied of this class of biopolymer is the capsular anionic polysaccharide of the oil-degrading bacterium Acinetobacter calcoaceticus RAG-1, emulsan. The emulsan polymer (MW, 106) consists of D-galacatosamine, D-galactosamine uronic acid (pKa, 3.01), and a diamino deoxyhexosamine. The amphipathic properties of emulsan are due in part to the presence of fatty acids linked to the polysaccharide backbone in both ester and amide linkages. Emulsan is characterized by a very high affinity for the oil/water interface, and its major industrial application is in the stabilization of oil-in-water emulsions at very low concentrations (emulsan : oil, 1 : 1000). This interfacial binding is accompanied by a conformational change in the polymer, which in turn allows for the concentration of normally water-soluble cations, proteins, and even phages in the oil layer after emulsion separation. Emulsan is now a commercial product produced by fermentation on an industrial scale. Two major applications are likely to involve its ability to stabilize heavy oil-in-water emulsions for (1) transportation in pipelines of high-viscosity oils at lower temperatures and (2) upgrading of high-viscosity fuels so that the homogeneous oil/water emulsions can be burned directly without water removal. Both applications have been tested on a semi-industrial scale and their feasibility has been demonstrated.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360260020
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    Synthesis and characterization of some 2,4′-dibenzyldiisocyanate ionic polymers. II. Cationic polyurethances using N,N′-bis-(β-hydroxyethyl)-piperazinePart I cf. lit5. (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 147 (1987), S. 99-106 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden kationische Polyurethane mit Piperazinringen in der makromolekularen Kette hergestellt. Die Polymeren bilden elastische und lichtdurchlässige Filme. Das Verhalten der verdünnten Lösungen in Lösungsmitteln mit verschiedenen Dielektrizitätskonstanten wurde untersucht.
    Notes: Cationic polyurethanes containing piperazine rings on the macromolecular chain were synthesized. The polymers form flexible and transparent films. The behaviour of diluted solutions in solvents of different dielectrical constants was studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051470109
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    The effect of various pigments on the rheological behaviour and morphology of polypropylene (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 147 (1987), S. 113-122 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In der vorliegenden Arbeit werden die Charakteristika von pigmentiertem Polypropylen (PP) untersucht. Die Ergebnisse zeigen, daß die Fließeigenschaften von PP-Schmelzen, die Morphologie und das Zugverhalten der Fasern deutlich von der Anwesenheit verschiedener, in der PP-Matrix dispergierter Pigmente beeinflußt werden. Die Auswirkungen verschiedener, dem PP zugefügten Pigmente zeigen große Unterschiede. Der Fließwiderstand von PP steigt mit Zugabe von Phthalocyaninblau, Ruß und Titandioxid, fällt aber bei der Anwesenheit von “BR red” und “GL orange” Die Strangaufweitungseffekte der PP-Schmelze werden durch Addition dieser Pigmente intensiviert. Die Elastizitätsgrenze von Fasern mit stäbchenförmiger Struktur ist 80-125% niedriger als die von Fasern mit Sphärulitstruktur.
    Notes: In this paper the characteristics of polypropylene (PP) containing pigments are systematically studied. The results show that the flow properties of PP melt, morphological structures, and drawing behaviour of the fibres are obviously affected by the presence of certain pigments dispersed in the PP matrix. The effects of various pigments added in PP display great difference. The flow resistance of PP increases with the addition of phthalocyanine blue, carbon black, and titanium dioxide, but decreases with the presence of BR red and GL orange. The extrudate swell effects of PP melt are intensified by adding these pigments. The yield stress of filaments with rod structure is 80-125% lower than that of filaments with spherulitic structure.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051470111
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    Propriétés de la Surface d'un Film de Polyéthylène Modifiée par Greffage d'un Oligomère Acrylique (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 147 (1987), S. 147-156 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The grafting of a liquid acrylic derivative (2-methylenepentane-1,5-dicarboxylic acid diethylester) on the surface of a polyethylene film (HD) was carried out in the presence of benzoylperoxide. The wettability of the surface was investigated with respect to the adhesion properties against aluminium and compared with those of a film of polyethylene grafted in mass with acrylic acid. The mobility of the surface grafted chains may cause the differences in the observed comportment.
    Notes: Le greffage d'un dérivé acrylique liquide (méthylène-2 pentanedïoate-1,5 de diéthyle) est effectué en présence de peroxyde de benzoyle à la surface d'un film de polyéthylène (HD). Les propriétés de mouillabilité de la surface sont examinées en relation avec les propriétés d'adhésion vis à vis de l'aluminium, et comparées avec celles d'un film de polyéthylène greffé dans la masse à l'acide acrylique. La mobilité des chaǐnes greffées à la surface pourrait ětre à l'origine des différences de comportement observées.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051470114
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  • 172
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    Study of polymerization of methacrylamide initiated by persulphate with different activators (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 150 (1987), S. 151-159 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Methacrylamid wurde in wäßriger Phase unter Verwendung von Persulfat/Äpfelsäure und Persulfat/Ethanolamin als Redox-Systeme unter Stickstoff untersucht. Bezüglich des Persulfats wurde für beide Fälle eine Reaktion erster Ordnung gefunden, für Äpfelsäure ergab sich die Ordnung 1/2, für Ethanolamin nullte Ordnung. Für Methacrylamid wurde im Ansatz mit K2S2O8/Äpfelsäure erste Ordnung und im Ansatz mit K2S2O8/Ethanolamin die Ordnung 1,5 gefunden. Das mittlere Molekulargewicht wurde viskosimetrisch für die unter verschiedenen Bedingungen erhaltenen Proben bestimmt.
    Notes: The aqueous polymerization of methacrylamide was studied by using persulphate/malic acid and persulphate/ethanolamine redox pairs under nitrogen atmosphere. The order with respect to persulphate was found to be one half with both the redox systems. Malic acid and ethanolamine show half order and zero order, respectively. Methacrylamide has first order dependence on the rate of polymerization initiated by K2S2O8-malic acid system and one and half order dependence on the rate of polymerization initiated by K2S2O8-ethanolamine redox pair. Viscometric average molecular weight was determined for the samples obtained under different kinetic conditions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051500112
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    Functionalization of atactic polypropylene using allyl and azide compounds (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 150 (1987), S. 1-11 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ataktisches Polypropylen wurde durch die Umsetzung mit Dicumylperoxid (8 Gew.-%) und einer Allylverbindung (8 Gew.-%) (Eugenolmethylether, Allylphenylether, Allylharnstoff, N-Allylthioharnstoff, Allylmalonsäurediethylester und N-Allylanilin) bei 170°C funktionalisiert. Bei der Reaktion von tert-Butylazidoformat mit ataktischem Polypropylen wurden maximal 1,8 Gew.-% Carbamatgruppen in das Polymere eingebaut. Die Mechanismen der beiden Reaktionstypen werden diskutiert.
    Notes: Atactic polypropylene was functionalized by reaction with dicumyl peroxide (8 wt.-%) and allyl compounds (8 wt.-%) such as eugenol methylether, allylphenylether, allylurea, N-allylthiourea, diethyl allylmalonate, N-allylaniline at 170°C. Using tert-butyl azidoformate carbamate groups (1.8 wt.-%) were attached to atactic polypropylene. The mechanism of both types of reactions is discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1987.051500101
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    Effect of hydrostatic pressure on the electrical conductivity of FEF carbon black-loaded sbr vulcanizates (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 150 (1987), S. 21-32 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde die elektrische Leitfähigkeit von Styrol-Butadien-Kautschuk (SBR-1502), der mit unterschiedlichen Konzentrationen von sehr schnell spritzbarem Furnace-Ruß (70, 80, 90 und 100 phr) beladen war, untersucht. Auf der Basis des Modells von Holm wurde eine qualitative Beschreibung für die elektrische Leitfähigkeit durch diese Verbundstoffe gesucht. Der Druckkoeffizient K wurde berechnet und zeigte eine starke Abhängigkeit von den Rußkonzentrationen.
    Notes: The electrical conduction was investigated in styrene butadiene rubber (SBR-1502) loaded with different concentrations of fast extrusion furnace (FEF) black (70, 80, 90, and 100 phr). On the bases of Holm's model, a qualitative description for the electrical conduction through these composites was sought. The pressure coefficient K was calculated and found to be strongly dependent on the carbon black concentrations.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1987.051500103
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    Characterization of low molecular compounds in dashboard foils by extraction, preparative high performance liquid chromatography, and IR-spectroscopy (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 150 (1987), S. 13-19 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird ein Verfahren zur Bestimmung der niedermolekularen Anteile von Instrumententafel-Folien beschrieben. Die Lösungsmittel-Extrakte der Folien werden mit Hilfe der präparativen Umkehr- bzw. Normalphasen-HPLC fraktioniert und die Fraktionen über ihre IR-Spektren charakterisiert. Vorzüge und Nachteile beider Verfahren werden diskutiert.
    Notes: A procedure to obtain information concerning the low molecular weight compounds of dashboard foils is described. Solvent extracts of the foils were fractionated by preparative reversed or normal phase HPLC, respectively. The fractions were characterized by their infrared spectra. The benefits and the shortcomings of the two methods are discussed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1987.051500102
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    Oberflächenstrukturierung polymerer Fasern durch UV-LaserbestrahlungTeil 2 cf. Lit.1.. 3. Synergetisches Modell für das Entstehen der OberflächenstrukturenAuszug aus der Dissertation von T. Bahners, Universität Duisburg 1987. (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 151 (1987), S. 39-47 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A synergetic model is proposed for the development of the surface structure on UV-Laser irradiated polymers and especially synthetic fibres. It is suggested that thermal contributions to the UV-laser-polymer-interaction produce a very thin, highly heated layer of molten material at the ablation limit. The formation of the typical surface structure is then thought to be caused by Marangoni-convection and shrinkage because of intrinsic stress. The parameters of the effect therefore are the absorption coefficient for the corresponding laser wavelength as a measure of the thickness of the molten layer and the existence of the shrinking behaviour.
    Notes: Ein synergetisches Modell wird vorgeschlagen für die Entstehung der Oberflächenstruktur von UV-laserbestrahlten Polymeren und speziell Synthesefasern. Dabei wird angenommen, daß durch thermische Beiträge zur UV-Laser-Polymer-Wechselwirkung eine sehr dünne, hocherhitzte Schmelzschicht an der Ablationsgrenze entsteht. Das Zusammenwirken von Marangoni-Konvektion und Schrumpfverhalten aufgrund innerer Spannungen ist dann für das Entstehen der typischen Struktur verantwortlich. Parameter für das Auftreten des Effekts sind hierbei der Absorptionskoeffizient für die jeweilige Wellenlänge, der die Dicke der Schmelzschicht bestimmt, sowie die Existenz des Schrumpfes.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1987.051510103
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    Oxygen transport and surface active properties of silicone containing copolymers of methyl methacrylate IIPart I cf. lit9. (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 151 (1987), S. 69-83 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden neue organofunktionelle Siloxane aus γ-Methacryloxypropyltrimethoxysilan (MPTMS) durch Umesterung von Methoxygruppen mit linearen höheren Alkoholen, Etheralkoholen und α-Hydroxysäuren hergestellt. Die Faktoren die die Substitutionsverhältnisse beeinflussen, wurden bestimmt.Diese Siloxane wurden mit Methylmethacrylat (MMA) copolymerisiert und mit Ethylenglykoldimethacrylat vernetzt, um den Einfluß der substituierten Gruppen auf den Sauerstoffpermeabilitätskoeffizienten (Pd) und die Eigenschaften der freien Oberflächenenergie der resultierenden Polymeren zu prüfen.Die Substitution der Sauerstoff enthaltenden polaren Gruppen erniedrigte die Sauerstoffdurchlässigkeit wegen der Wechselwirkungen zwischen den polaren Gruppen, die das freie Volumen erniedrigen. Diese Gruppen jedoch erhohten die polare Komponente der freien Oberflächenenergie (γPS) und somit die gesamte freie Oberflgchenenergie (γS). Die Hydrophilie der Carbitol und 2-Ethoxyethanol enthaltenden Siloxan-Methylmethacrylat-Copolymeren macht sie fur biomedizinische Anwendungen geeignet.
    Notes: New organofunctional siloxanes from γ-methacryloxypropyltrimethoxysilane (MPTMS) were synthesized by transesterification of methoxy groups with linear high alcohols, ether alcohols, and α-hydroxyacids. The factors affecting the substitution ratios were determined.These siloxanes were copolymerized with methyl methacrylate (MMA), crosslinked with ethylene glycol dimethacrylate (EGDM) in order to examine the effect of substituted groups to the oxygen permeability coefficient (Pd) and surface free energy properties of the resultant copolymers.The substitution of the oxygen containing polar groups decreased the oxygen permeability due to the interactions between polar groups decreasing the free volume. However, these groups increased the polar component of surface free energy (γSP) and thus total surface free energy (γS). The hydrophilicity of the carbitol and 2-ethoxyethanol containing siloxane-MMA copolymers was found to be suitable for biomedical applications.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051510105
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    Mitteilungen (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 151 (1987), S. 275-275 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051510108
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  • 179
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    A model for predicting elongational viscosity of polymer blends (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 151 (1987), S. 95-101 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird ein Modell vorgeschlagen, nach dem die Dehnungsviskosität von Blends mit der Theorie des Freien Volumens so korreliert werden kann, daß die Dehnungsviskosität eines Blends für jede Zusammensetzung aus den Dehnungsviskositäten und dem Gewichtsbruch der Komponenten bestimmt werden kann. Die Voraussagen des Modells wurden an experimentellen Daten in vier Fällen überprüft.
    Notes: A model has been proposed to correlate the elongational viscosity of blends with the free volume theory so that the elongational viscosity of a blend at any composition can be determined from the elongational viscosity and the weight fractions of the individual components. The predictions of the model are compared with experimental data in four cases and found to give reasonable good agreement.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051510107
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  • 180
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    Synthesis and thermal studies of bisitaconimide-methacrylic acid copolymers (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 21-31 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Copolymeres aus 3,3′-Bisitaconimido-m,m′-diphenylsulfon und Methacrylsäure wurde in einer radikalischen Polymerisation hergestellt. Das Copolymere wurde charakterisiert und die Copolymerisationsparameter ermittelt. Die durch drei verschiedene Methoden erhaltenen Reaktivitätsverhältnisse stimmen gut überein und lassen auf ein alternierendes Copolymeres schließen. Der thermische Abbau des Bisitaconimidhomopolymeren und des Copolymeren wurden verglichen und das thermische Verhalten diskutiert. Die Aktivierungsenergien für die verschiedenen Stufen des thermischen Abbaus des Homo- und des Copolymeren wurden durch Coats-Redfarn-Diagramme ermittelt.
    Notes: A copolymer of 3,3′-bisitaconimido-m,m′-diphenyl sulfone and methacrylic acid was synthesized by free radical polymerization. The copolymer was characterized and the copolymerization parameters were evaluated. The reactivity ratios determined by three different methods were in good agreement and the values suggest an alternating copolymer. The thermal degradation of the bisitaconimide homopolymer and the copolymer were compared and the structural implications on the thermal behaviour are discussed. The activation energies for the different stages of thermal decomposition of both the homopolymer and the copolymer were evaluated from the Coats-Redfarn plots.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520103
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  • 181
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    Untersuchungen zur thermodynamischen verträglichkeit von polyethylen hoher dichte (HD PE) und polyethylen niederer dichte (LD PE) in schmelzezustand, II. Die spezifische freie mischungsenthalpie (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 15-20 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The parameters of solubility of HD PE and LD PE were used to calculate the Flory-Huggins-interaction parameter χ12 and, from this, the specific free mixing enthalpy ΔGm/V was determined according to Flory-Huggins for a system of these components. The diffusion rate of the PE molecules was estimated using the reptation model and the Einstein relation.The motive power of diffusion is proportional to the specific free mixing enthalpy. The results show that diffusion controlled segregation does not run in a HD PE/LD PE blend in the state of melt. This means that the morphology of polyethylene blends is only determined by mixing conditions in connection with the flow properties of components.
    Notes: Aus den Löslichkeitsparametern von HD PE und LD PE wurde ihr temperaturabhängiger Flory-Huggins-Wechselwirkungsparameter χ12 und daraus wiederum nach Flory-Huggins die spezifische freie Mischungsenthalpie ΔGm/V eines HD PE/LD PE-Systems berechnet. Unter Zuhilfenahme des „reptation“-Modells und der Einstein-Relation wurde die Diffusionsgeschwindigkeit der PE-Moleküle abgeschätzt. Die Triebkraft dieser Diffusion ist proportional der spezifischen freien Mischungsenthalphie. Die Ergebnisse zeigen, daß diffusionskontrollierte Entmischungserscheinungen in einer HD PE/LD PE-Mischung im Schmelzezustand nicht ablaufen. Das bedeutet, daß die Morphologie der Mischungen im Schmelzezustand nur durch die Mischbedingungen im Zusammenspiel mit den Fließeigenschaften der Komponenten festgelegt wird.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520102
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  • 182
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    Influence of synthesis conditions of porous copolymers of 1,4-di(methacryloyloxymethyl)-naphthalene with divinylbenzene on their structure, 2Part 1 cf. lit.7.. Influence of diluent composition (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 33-39 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde der Einfluß der Lösungsmittelzusammensetzung aus Toluol und n-Decanol auf die innere Struktur poröser Copolymerer untersucht.Eine Serie von Copolymeren mit jeweils 50 mol-% 1,4-Di(methacryloyloxymethyl)-naphthalin (1,4-DMN) und Divinylbenzol (DVB) wurde in Anwesenheit unterschiedlicher Anteile Toluol in der Mischung mit n-Decanol hergestellt. Um den Einfluß der Toluolkonzentration auf die innere Struktur der porösen Polymeren zu bestimmen, wurden die spezifische Oberfläche, die Porengrößenverteilung sowie die Polarität des Quellungsmittels untersucht.
    Notes: The influence of diluent composition on the internal structure of porous copolymers of 1,4-di(methacryloyloxymethyl)naphthalene (1,4-DMN) and divinylbenzene (DVB) was studied.A set of copolymers containing 0.5 mole fraction of 1,4-DMN and 0.5 mole fraction of DVB obtained in the presence of various amounts of toluene in the mixture with n-decanol was investigated. In order to establish the influence of toluene concentration on the internal structure of 1,4-DMN and DVB copolymers, surface areas, pore size distributions, and polarities of sorbents were investigated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520104
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  • 183
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    Untersuchungen zur thermodynamischen verträglichkeit von polyethylen hoher dichte (HD PE) und polyethylen niederer dichte (LD PE) im schmelzezustand, I. Die bestimmung der löslichkeitsparameter (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 1-13 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The solubility parameters of HD PE and LD PE above crystallization temperatures were determined on the basis of gas chromatographical retention data. The method of inverse gas chromatography was used. It showed that the solubility parameters of the types of polyethylene investigated are nearly equal within the margin of error. From the dependence of the solubility parameters on the temperature follows that the thermodynamical behaviour of the polyethylene components in mixtures is determined by their different free volumes.
    Notes: Für HD PE und LD PE wurden oberhalb der Kristallisationstemperaturen die Löslichkeitsparameter auf der Basis gaschromatographischer Retentionsdaten bestimmt. Als Meßverfahren wurde die Methode der Inversen Gaschromatographie angewendet. Es zeigte sich, daß die Löslichkeitsparameter der untersuchten Polyethylentypen innerhalb der Fehlergrenzen nahezu gleich sind. Aus der Beschreibung der Temperaturabhängigkeit der Löslichkeitsparameter folgt, daß das thermodynamische Verhalten der Polyethylenkomponenten in Mischungen durch ihre unterschiedlichen freien Volumina determiniert ist.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520101
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  • 184
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    Effect of the structure of slightly crosslinked polyurethanes on their thermal stability (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 41-53 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die schwachvernetzten Polyurethane mit Allophanat- und C—C - Bindungen wurden durch die Reaktion von 4,4′-Diphenylmethandiisocyanat mit einer Poly(ethylenadipat)/Poly(ethylenmaleat)-Mischung sowie mit einer Mischung aus Terephthal-Adipinsäure-Copolyesterdiol und niedermolekularen Diolen hergestellt.Die Ergebnisse der isothermen und dynamischen thermischen Analyse in inerter Atmosphäre zeigen, daß die thermische Stabilität der Polyurethane von der Vernetzungsdichte und der chemischen Struktur der Vernetzungsbindungen und der Hart-Segmente unabhängig ist.
    Notes: Polyurethanes slightly crosslinked with allophanate and C—C linkages have been prepared by reaction of 4,4′-diphenylmethane diisocyanate with poly(ethylene adipate) and poly(ethylene maleate) as well as with terephthalic-adipic copolyesterdiol and some low molecular diols.Data obtained from isothermal and dynamic thermogravimetric analysis carried out in an inert atmosphere indicate that the thermal stability of polyurethanes is independent on the crosslinking density and the structural characteristics of crosslinks and hard segments.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520105
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  • 185
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    Reaction of poly(vinyl alcohol) with n-butyl isocyanate. Chemical hydrolysis of the resulting polymers (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 79-91 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Diese Untersuchung befaßt sich mit einigen kinetischen Merkmalen der Reaktion von n-Butylisocyanat mit Polyvinylalkohol ohne jeden Katalysator und unter Verwendung von Triethylendiamin als Katalysator. Die Struktur der resultierenden Polymeren wurde mit Hilfe der IR-, 1H-, und 13C-NMR-Spektroskopie und chemischer Analyse ermittelt. Es wurden Vinylalkohol-Vinylbutylurethancopolymere (VAL-VBU) erhalten. Es ergab sich eine lineare Abhängigkeit der Reaktionsgeschwindigkeit von Polymer-, n-Butylisocyanat- und Triethylendiaminkonzentration. Die Reaktionsgeschwindigkeitskonstante nimmt mit zunehmender Reaktionszeit ab. Das kann mit der sterischen Hinderung durch die Urethangruppen, die entlang der Polymerkette eingebaut sind, erklärt werden. Die Aktivierungsenergie ergab sich zu 49,9 kJ/mol. Eine kinetische Untersuchung der homogenen Hydrolyse von VAL-VBU-Copolymeren wurde durchgefilhrt als Funktion der Basenkonzentration, der Temperatur und des VBU Gehalts. Es zeigte sich, daß die homogene Hydrolyse als Reaktion 1 . Ordnung verliluft, sowohl im Hinblick auf die Hydroxylionen als auch auf den VBU-Gehalt. Die Aktivierungsenergie filr die basenkatalysierte Hydrolyse betragt 79,3 kJ/mol. Die heterogene Hydrolyse von VAL-VBU-Copolymeren im basischen Medium zeigte, daß keine Hydrolyse unter diesen Bedingungen stattfand.
    Notes: This study is concerned with some kinetic features of the reaction of n-butyl isocyanate with poly(vinyl alcohol) without any catalyst and using triethylene diamine as catalyst. The structure of the resulting polymers was determined by means of IR, 1H- and 13C-NMR spectroscopy as well as by chemical analysis. Vinyl alcohol-vinyl butyl urethane (VAL-VBU) copolymers were obtained. It has been found a linear dependence of reaction rate on polymer, n-butyl isocyanate, and triethylene diamine concentrations. Reaction rate constant decreases as reaction time increases. It can be explained by steric hindrance phenomena due to urethane groups incorporated along the polymeric chain. The activation energy was found to be 49.9 kJ/mol. A kinetic study of the homogeneous hydrolysis of VAL-VBU copolymers has been made as a function of the base concentration, the temperature, and the VBU content. The homogeneous hydrolysis was found to be first order with respect to both hydroxyl ion and VBU contents. The activation energy for the base catalyzed homogeneous hydrolysis was found to be 79.3 kJ/mol. The heterogeneous hydrolysis of VAL-VBU copolymers in basic medium showed that no hydrolysis takes place under the conditions employed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520108
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  • 186
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    Studies on 50/50 natural rubber/styrene butadiene copolymer blendDedicated to Prof. R. Anantaraman on his 61st birthday (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 107-119 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein mit Ruß gefülltes 50/50 NR/SBR-Blend (Naturkautschuk/Styrol-Butadien-Copolymer) wurde unter Verwendung verschiedener konventioneller Vernetzungssysteme, die durch unterschiedliche Schwefel- und Beschleunigeranteile gekennzeichnet sind, vulkanisiert. Die Vulkanisationscharakteristiken und die Eigenschaften der Vulkanisate wurden verglichen. Das Ausmaß und die Qualität der Vernetzungsstellen wurden für jeden Fall durch chemische Testmethoden ermittelt, um sie mit den Vulkanisateigenschaften zu vergleichen.
    Notes: A carbon black filled 50/50 natural rubber (NR)/styrene-butadiene rubber (SBR) blend is vulcanized using several conventional curing systems designed by varying the amounts of sulphur and accelerator. The cure characteristics and the properties of the vulcanizates are compared. The quantity and quality of crosslinks in each case are evaluated by chemical probes to correlate them with the vulcanizate properties.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520110
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  • 187
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    Solution properties of ultrahigh molecular weight polymers, 15Part 14: Rev. Roum. Chim. 31 (1986) 995.. A viscometric study of poly(isobutyl methacrylate) in different solvents (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 121-131 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Arbeit stellt eine Erweiterung der vorhergehenden Untersuchungen hinsichtlich synthetischer Polymerer mit sehr großen Molekularmassen dar. Die Grenzviskositäten und die Viskositätskonstanten von Poly(isobutylmethacrylat) wurden mit den Methoden von Huggins, Kraemer, Martin, Schulz-Blaschke und Fedors in CCl4 und C6H6 bei 25°C erhalten. Es wurde beobachtet, daß die Methode von Fedors nicht sehr sensibel ist bei den möglichen Fehlern, die bei der Bestimmung der relativen Viskositäten in konzentrierten Bereichen auftreten. Diese Methode führt zu Grenzviskositäten, die nahe den mittleren Werten liegen, die mit den anderen fünf Methoden und der Sakai-Mitteilung erhalten wurden. Außerdem wurden die Umwandlungskonzentrationen, die die verdünnt-halbverdünnten Bereiche trennen, sowie die Mark-Houwink-Konstanten bestimmt.
    Notes: The paper extends previous studies on ultrahigh molecular weight synthetic polymers. The intrinsic viscosities and the viscosity constants of poly(isobutyl methacrylate) fractions were obtained by the methods of Huggins, Kraemer, Martin, Schulz-Blaschke, and Fedors in CCl4 and C6H6 at 25°C. It was observed that the method of Fedors is not very sensitive to the possible errors appearing in estimating the relative viscosities in higher concentration domains. This method yields intrinsic viscosity values close to the mean values obtained from the other five methods and to the values calculated according to the averaging procedure suggested by Sakai. The transition concentrations separating the concentration domains (diluted-semidiluted) and the Mark-Houwink constants were obtained.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520111
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  • 188
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    Radiation initiated grafting of styrene and methyl methacrylate onto wool (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 133-147 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die strahleninduzierten Pfropfungen der hydrophoben Monomeren Styrol und Methylmethacrylat sowohl auf gefärbtem Teppich als auch auf gefärbter und ungefärbter Wolle werden ausgeführt. Betont wird die Notwendigkeit des Quellens zur Erzielung einer merkbaren Pfropfausbeute. Es wurde gefunden, daß die Pfropfungsgeschwindigkeit für die gefärbte Wolle wie auch für den Teppich kleiner ist als für die ungefärbte Wolle. Diese Ergebnisse werden erklärt mit der abschirmenden Wirkung der aromatischen Farbstoffmolekülteile. Bei geringen Monomerkonzentrationen wurde ein Umsatz von 97% bezogen auf die eingesetzte Monomermenge gefunden, da die als Nebenreaktion ablaufende Homopolymerisation in Gegenwart von Radikalabfängern fast vernachlässigbar ist. Eine angemessene Hydrophobie wurde erreicht bei mit ca. 80% Styrol und ca. 150% Methylmethacrylat gepfropfter Wolle.
    Notes: Radiation initiated grafting of hydrophobic monomers styrene and methyl methacrylate onto wool (dyed and undyed) and dyed carpet has been carried out. The importance of swelling in obtaining appreciable amounts of grafting has been stressed. The rate of grafting with dyed wool and carpet is found to be less than for undyed wool and the results are explained on the basis of protection offered by aromatic moieties of the dye. Efficiency of monomer utilization has been found to be as high as 98% at low concentrations of the monomer since the accompanying (parasitic) homopolymerisation is almost negligible in the presence of scavengers. Reasonable hydrophobicity is achieved in ca. 80% styrene grafted and ca. 150% methyl methacrylate grafted wool.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520112
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  • 189
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    Fließverhalten von Mischungen aus chloriertem Polyethylen und Polymethylmethacrylat (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 155 (1987), S. 163-175 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The flow behavior of bicomponent polymer blends of chlorinated polyethylene (PEC) and poly(methyl methacrylate) (PMMA) is presented in the form of flow curves. The relations between the rheological measurements and the morphology are discussed. The blends (PEC/PMMA, chlorinated up to 40 wt.-%) show the characteristic behavior of incompatible systems, some of them with a second highly dispersed phase. In addition a system of PE/PMMA is examined, the PE being the raw material of the PEC. The influence of the chlorination on flow behavior and the biphase structure is obvious.
    Notes: Das Fließverhalten von Mischungen aus chloriertem Polyethylen (PEC) und Polymethylmethacrylat (PMMA) wird in Form von Fließkurven dargestellt. Die Ergebnisse der rheologischen Messungen werden anhand der sich ausbildenden Morphologie diskutiert. Es zeigt sich, daß die untersuchten Mischungen aus PEC/PMMA mit Chlorierungsgraden bis 40 Gew.-% Cl das charakteristische Verhalten von unverträglichen (2-phasigen) Mischungen mit teilweise fein dispergierter zweiter Phase liefern. Vergleichend wird die Stoffkombination PE/PMMA betrachtet, wobei die PE-Sorten jeweils die unchlorierten Ausgangsprodukte darstellen. Der Einfluß der Chlorierung auf das Fließverhalten und die zweiphasige Struktur ist deutlich festzustellen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051550114
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  • 190
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    Preparation and properties of selectively p-chlorinated polystyrene (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 155 (1987), S. 191-197 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polystyrol wurde in Lösung mit SbCl3 als Katalysator und 10-Trifluoracetylphenothiazin als Cokatalysator chloriert. Dabei wurde ein Polymeres erhalten, das durch die Formel . beschrieben werden kann. Die aromatische Substitutionsreaktion (x 〉 1) erfolgt vorwiegend and der para-Position; das Verhältnis der para- zur ortho-Chlorierung beträgt 10 - 12. Die Grenzviskositätszahl bei 30°C einer toluolischen Polymerlösung nimmt mit dem Chlorgehalt x des Polymeren ab. Der Brechungsindex nD wächst mit x. Der nD - Wert eines Polymeren mit 25,05 Gew.-% Chlor (x ≃ 1) beträgt 1,6041.
    Notes: Polystyrene has been chlorinated in the liquid phase by SbCl3 catalyst combined with 10-trifluoroacetylphenothiazine to afford a polymer, which is represented by the formula . The aromatic substitution reaction (x 〉 1) occurs predominantly at the p-position, the ratio of p- to o-chlorination being 10-12. The intrinsic viscosity of the toluene solution at 30°C decreases with content of chlorine, x. The refractive index, nD, increases with x. The nD value of a 25.05% chlorine-containing polymer (x ≃ 1) is 1.6041.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051550116
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  • 191
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    Interactions of polymer backbones and complexation of polychelatogens with methylthiourea ligands in aqueous solutionDedicated to Prof. Dr. E. Bayer on the occasion of his 60th birthday (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 155 (1987), S. 151-161 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Wechselwirkungen des Polymergerüsts und die Komplexbildung mit einer Reihe von Schwermetallen wurde für die Methylthioharnstoff als Liganden tragenden Basispolymeren Poly(ethylenimin), Poly(vinylpyrrolidinon) und Poly(acrylamid) in Abhängigkeit vom pH-Wert untersucht.Retentionsstudien in wässriger Lösung unter Verwendung von Membranfiltration wurden zur Bewertung der Wechselwirkungen zwischen Metallionen und Makromolekülen in Abhängigkeit vom pH-Wert herangezogen. Es wurde für die Ionen Na, Co, Ni, Cu, Zn, Cd, Hg, Fe gezeigt, daß die Wechselwirkung sowohl von der Art des Polymergerüsts als auch vom pH abhängt. Während die Retentionswerte von Copolymeren auf der Basis von Poly(ethylenimin) nur schwach vom pH beeinflußt wurden, zeigten die beiden anderen untersuchten Copolymeren eine starke Abhlngigkeit für die einzelnen Metalle. Es wurde eine vorherrschende Wirkung des funktionellen Liganden-Comonomeren hinsichtlich der Wechselwirkung im Vergleich zum Basismonomeren füur den größten Teil der untersuchten Metallionen gefunden.
    Notes: The interactions of the polymeric backbone and complex formation with a series of metals were investigated for poly(ethyleneimine), poly(vinylpyrrolidinone), and poly-(acrylamide) as basis polymers with methylthiourea as ligand. Retention studies by application of membrane filtration of aqueous solutions were used for the evaluation of interaction between the metal ions and macromolecules as function of pH. It was shown for the Na, Co, Ni, Cu, Zn, Cd, Hg, Fe ions that the interaction depends both on the type of polymer backbone and the pH.Whereas for poly(ethyleneimine)-based copolymers the retention data were influenced only slightly by pH, the two other copolymers investigated showed a strong pH dependency for the individual metals. A dominating effect of the functional ligand comonomer in terms of the interaction over the basis monomer was observed for the majority of metal ions investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051550113
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  • 192
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    The laser flash-initiated polymerization as a tool of evaluating (individual) kinetic constants of free radical polymerization, 3Part 2: cf. lit6.. Information from degrees of polymerization (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 155 (1987), S. 177-190 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Für die in einer pseudostationären Laserpuls-induzierten Photopolymerization entstehenden Polymeren werden Gleichungen für die Zahlen- und den Masenmittelwert der Polymerisationsgrade abgeleitet. Der Kettenabbruch kann dabei, bei vernachlässigbarer Kettenübertragun, in einer Disproportionierung oder einer Rekombination bestehen. Die Analyse der bei verschiedenen Pulsabständen resultierenden Polymerisationsgrade ermöglicht die Bestimmung der Wachstumskonstanten (kp) und des Produkts kt ρ (kt = Geschwindigkeitskonstante des bimolekularen Kettenabbruchs, ρ = Konzentration der pro Laserblitz produzierten Primärradikale). Da überdies k2/kt%/& aus der (pseudostätionaren) Polymerisationsgeschwindigkeit und dem Massenmittel-Polymerisationsgrad des im selben Experiment gebildeten Polymeren berechnet werden kann, ist es, zumindest im Prinzip, möglich, eine vollstähdige Auflösung in die individuellen GröBen kp, kt und ρ zu erreichen. Anhand eines Beispiels läßt sich zeigen, daß die auf diesem Weg für die Styrolpolymerisation bei 25°C gewonnenen Daten gut mit jenen übereinstimmen, die mittels anderer Methoden erhalten wurden.
    Notes: Equations are derived for the number average and the weight average degrees of polymerization for the polymer forming in a laser-initiated photo-polymerization under pseudostationary conditions when termination occurs by disproportionation or recombination and if chain transfer is negligible. Analysis of the degrees of polymerization at various pulse separations leads to information on the rate coefficient of propagation (kp) and on the product kt ρ (kt = rate coefficient of bimolecular chain termination, ρ = concentration of primary radicals produced in each flash). As kp2/kt may be evaluated from the rate and the weight average degree of polymerization P̄w of a single pseudostationary experiment, at least in principle, a complete resolution into individual constants may be achieved. It is demonstrated in an example that the data obtained in this way for the polymerization of styrene at 25°C are well consistent with those originating from other methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051550115
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  • 193
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    Mitteilungen (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 155 (1987), S. 199-200 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051550117
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  • 194
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    The role of the stress resultant in determining mechanical equilibria of superhelical DNA (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 9-15 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260105
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  • 195
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    A model of the hydrodynamic behavior of irradiated DNA: Dependence on molecular conformation (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 59-82 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The model presented here describes the DNA viscosity and viscoelastometric responses to ionizing radiation-induced molecular breakdown. Four DNA conformations are considered: (1) linear chain, (2) relaxed circle, (3) supercoiled circle, and (4) supercoiled linear. The model includes the systems of differential equations for calculating the size distributions of DNA molecules as functions of dose. Thedistributions are used in the usual hydrodynamic formulae for heterogeneouspopulations of polymer molecules. The sensitivity of viscoelastometry for the estimation of D37 is better than that of viscometry. The model predicts a considerable difference between the radiation responsesof linear and circular DNAs. The prediction is confirmed by experimental data for T4 DNA [C. S. Lange et al. (1984) Rad. Res. 100, 1-15] and E. coli DNA [S. E. Bresler et al. (1984) Biophys. J. 45, 749-754]. Thus, ionizing radiation can be used to determine the original conformation of DNA molecules.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260109
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  • 196
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    Proton polarizability and proton transfer in histidine-phosphate hydrogen bonds as a function of cations present: Ir investigations (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 95-108 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (L-His)n- dihydrogen phosphate systems are studied by ir spectroscopy in the presence of various cations and as a function of the degree of hydration. Ir continua indicate that (I) OH … N ⇌ O-…H+N (IIR) hydrogen bonds are formed and that these bonds show high proton polarizability, which increases from the Li+ to the K+ system. In the K+-system, His-Pi-Pi chains are formed, showing particularly high proton polarizability due to collective proton motion within both hydrogen bonds. The OH N ⇌ O-…H-N equilibria are determined from ir bands. With the Li+ system, 55% of the protons are present at the histidine residues; this percentage is smaller with the Na+ system (41%), and amounts to only 32% with the K+ system. With the increasing degree of hydration the removal of the degeneracy of νas-PO2-3 vanishes, indicating loosening of the cations from the phosphates. Nevertheless, the hydrogen bond acceptor O atom becomes more negative; a shift of the equilibrium to the right is observed in the OH… N ⇌ O-…H+N bond. This is explained by the strong interaction of the dipole of the hydrogen bonds with the water molecules. All these results show that protons can be shifted easily in these hydrogen bonds due to their high proton polarizability. The transfer equilibria can be controlled easily by local electrical fields. In addition, these results may be of significance when phosphates interact with proteins.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260111
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  • 197
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    The hydrogen bonding of cytosine with guanine: Calorimetric and 1H-NMR analysis of the molecular interactions of nucleic acid bases (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 591-603 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enthalpy of hydrogen-bond formation between guanine (G) and cytosine (C) in o-dichlorobenzene and in chloroform at 25°C has been determined by direct calorimetric measurement. We derivatized 2′-deoxyguanosine and 2′-deoxycytidine at the 5′- and 3′-hydroxyls with triisopropylsilyl groups; these groups increase the solubility of the nucleic acid bases in nonaqueous solvents. Such derivatization also prevents the ribose hydroxyls from forming hydrogen bonds. Consequently, hydrogen-bond formation in our system is primarily between the bases, and to a lesser extent, between base and solvent, and can be measured directly with calorimetry. To obtain the data on base-pair formation, we first took into account the contributions from self-association of each base, and where possible, have determined the ΔH of self-association. From isoperibolic titration calorimetry, our measured ΔH of C2 formation in chloroform is -1.7 kcal/mol of C. Our measured ΔH of C:G base-pair formation in o-dichlorobenzene is -6.65 ± 0.32 kcal/mol. Since o-dichlorobenzene does not form hydrogen bonds, the ΔH of C:G base-pair formation in this solvent represents the ΔH of the hydrogen-bonding interaction of C with G in a nonassociating solvent. In contrast, our measured ΔH of C:G base-pair formation in chloroform is -5.77 ± 0.20 kcal/mol; thus, the absolute value of the enthalpy of hydrogen bonding in the C:G base pair is greater in o-dichlorobenzene than in chloroform. Since chloroform is a solvent known to form hydrogen bonds, the decrease in enthalpic contribution to C:G base pairing in chloroform is due to the formation of hydrogen bonds between the bases and the solvent. The ΔH of hydrogen bonding of G with C reported here differs from previous indirect estimates: Our measurements indicate the ΔH is 50% less in magnitude than the ΔH based on spectroscopic measurements of the extent of interaction. We have also observed that the enthalpy of hydrogen bonding of C with G in chloroform is greater when G is in excess than when C is in excess. This increased heat is due to the formation of C:Gn 〉 1 complexes that we have observed using 1H-nmr. Although C:G2 structures have previously been observed in triple-stranded polymeric nucleic acids, higher order structures have not been observed between C and G monomers in nonaqueous solvents until now. By using monomers as a model system to investigate hydrogen-bonding interactions in DNA and RNA, we have obtained the following results: A direct measurement of the ΔH of hydrogen bonding in the C:G complex in two nonaqueous solvents, and the first observation of C:Gn 〉 1 complexes between monomers. These results reinforce the importance of hydrogen bonding in the stabilization of various nucleic acid secondary and tertiary structures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260411
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  • 198
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    Thermodynamics of water-biopolymer interactions: Irreversible sorption by two uniform sorbent phases (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 387-401 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to understand the mutual interactions between water and a biopolymer, thermodynamic analysis of sorption isotherms of water vapor by the biopolymer is necessary. These isotherms are irreversible and show sorption hysteresis. The reasons for such behavior are not established. As a continuation of previous work, general relationships for thermodynamic quantities of sorption are derived for the general case when the sorbent consists of two uniform phases. As in the case of a single sorbent phase, the Clausius-Clapeyron equation can be used to obtain differential entropies of sorption. Two special cases for the two-phase situation - equilibrium hysteresis and partial equilibrium hysteresis - are plausible models for the irreversibility seen in water-biopolymer interactions. When differential entropy of sorption is plotted as a function of amount of water sorbed per mole of biopolymer, irregularities are generally seen. It is suggested that these irregularities reflect changes in conformation and/or dynamics of the biopolymer molecule.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260307
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  • 199
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    Masthead (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260401
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  • 200
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    Conformation of DNA in solution: CD calculations based on crystal structures of B- and Z-DNA fragments (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 457-461 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260402
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