bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term change in conformation of macromolecules in solution, 2. Poly(acrylamide‐co‐sodium acrylate)s
Authors: Kulicke Werner‐Michael , Kniewske Reinhard 
Published: April 2003

AbstractThe solution viscosity of aqueous poly(acrylamide‐co‐sodiumacrylate)s decreases with time in the scale of weeks. This unusual viscosity loss has been investigated by viscometry and by light scattering on high purity copolymer samples with different ratios of the components. — No viscosity loss can be observed in NaCl solution of high enough salt concentration. From the experiments it is concluded that a conformational change causes the viscosity decrease. No chain scission occurs. Light scattering measurements were used to directly confirm this hypothesis. — The viscosity loss may be caused by a conformational change of single molecules involving hydrogen bonds and can be interpreted as a transition from a partly stiffer, higher viscous structure to a more flexible one. As the driving force for the conformational change the entropy is discussed. The pronounced time dependence may be interpreted by a cooperative effect of loosening and combining of hydrogen bonds. — A similar behaviour has been observed earlier in aqueous poly(acrylamide) solutions. Thus, for some water soluble polymers one has to be aware of a time dependent parameter.
Syntheses of thermotropic liquid crystalline polymers, 2. polyurethanes
Authors: Iimura Kazuyoshi , Koide Naoyuki , Tanabe Hideo , Takeda Masatami 
Published: April 2003

AbstractPolyurethanes were synthesized by reaction of a rigid molecule, 3,3′‐dimethyl‐4,4′‐biphenyldiyl diisocyanate (DBD), with flexible molecules, oligoethylene glycols (di‐, tri‐, and tetraethylene glycol) or α,ω‐alkanediols, and some of their thermal properties were studied. Poly(DBD‐oligoethylene glycol)s are amorphous polymers which exhibit no mesomorphic phase. Poly(DBD‐alkanediol)s are found to show a mesomorphic phase depending on the number of methylene units in the alkanediol. The polymers having methylene units from five to twelve are crystalline and show a mesomorphic phase. On the contrary, polymers having less than four methylene units do not show a mesomorphic phase since thermal decomposition of the polymers occurs before melting. The transition temperature from the mesomorphic phase to the isotropic liquid decreases with increasing length of the flexible chain of alkanediol. Ternary polymers are obtained by reaction of DBD with a mixture of hexanediol (HD) and dodecanediol (DD). The ternary polymers containing a small amount of HD and DD give a clear mesomorphic phase.
Adiabatic polymerization of ε‐caprolactam in presence of lithium chloride, 2. Properties of the resultant polymer
Authors: Alfonso Giovanni Carlo , Pedemonte Enrico , Russo Saverio , Turturro Antonio 
Published: April 2003

AbstractPhysical and mechanical properties of poly(ε‐caprolactam) synthesized in presence of various amounts of lithium chloride are measured on compression moulded films and correlated to the molecular organization, both in the amorphous and in the crystalline regions. By increasing the amount of LiCl present in the system it can be observed a heigtening of Tg and density of the amorphous phase as well as an increase of tensile modulus and yield strength. A transition from ductile to brittle failure occurs for both semicrystalline and amorphous samples in dry conditions, when the salt content in the amorphous phase is about 6 wt.‐%. These phenomena and the capability of the salt to reduce the crystallinity of the polymer are interpreted in the frame of the already accepted model of ion‐dipole interactions between lithium ion and the carbonyl groups of the polyamide. Effects due to moisture uptake are also discussed.
The rôle of water in the metachromatic reaction
Authors: Lawton John B. , Phillips Glyn O. 
Published: April 2003

AbstractThe effect of water on the metachromatic complexes of methylene blue and cellulosic polyanions has been studied by diffuse reflectance spectroscopy. Complete dehydration causes the complexes to become orthochromatic and rehumidification reverses the change. These effects are explained in terms of site‐binding. It is postulated that the dye cations are bound more tightly in the anhydrous state and this modifies the dye‐dye interactions that are the cause of the metachromatic colour change. Anionic celluloses produced hypsochromic shifts in the absorption spectrum of the dye in the order: sulfate > phosphate > carboxyl > carboxymethyl. This is the reverse of the order of electrostatic attractions between the sites and the dye cations. Such attractions are shown to modify dye‐dye interactions, with the result that for a given spacing of negative sites, the polycarboxylates initiate least metachromatic colour change.
Liquid crystalline polymers, 8. Structurally ordered thermotropic polyesters of glycol ethers
Authors: Galli Giancarlo , Chiellini Emo , Ober Christopher K. , Lenz Robert W. 
Published: April 2003

AbstractA series of polysters based on a triad aromatic ester mesogenic unit but containing different poly(alkylene oxide) flexible spacers in the main chain was prepared and its properties examined. The flexible spacers consisted of poly(alkylene oxide)s of varying lengths based on either oligomers of ethylene oxide or propylene oxide. The spacer types, lengths and distributions were found to strongly affect the mesophase and melting behaviors of the polymers. Polymers with spacers having more than 10 units were not liquid crystalline, whereas those of shorter length exhibited mesophase properties. The polymers containing spacers with two, three, or four oxyethylene units showed two mesophases, and the textures of their mesophases suggested that both smectic and nematic phases were formed.
A kinetic study of the thermal degradation of cellulose and its derivatives
Authors: Jain Rajesh K. , Lal Krishan , Bhatnagar Hari L. 
Published: April 2003

AbstractThe kinetics of the pyrolysis of cellulose and its derivatives (2,2‐dichloropropionate and acetate) in nitrogen and air were studied by dynamic thermogravimetry and differential thermal analysis from ambient temperature to 600°C. From the resulting data various thermodynamic parameters could be obtained following the methods of Freeman and Carroll, Broido, and Dave and Chopra. The values of ΔE* for cellulose and its derivatives were found to be in the range 120 to 260 kJ · mol−1. However, the values of the free energy of activation for the degradation of cellulose and its derivatives are almost the same, i. e. 187 to 199 kJ · mol−1, indicating that the basic steps for the thermal degradation of cellulose and its derivatives are the same. Based on Scotney's work on the thermal degradation of cellulose triacetate, a mechanism for the thermal degradation of cellulose 2,2‐dichloropropionate is proposed. The IR spectra of the pyrolysis residues of cellulose dichloropropionate indicate that dehydration takes place and a compound containing carbonyl groups is formed.
Polymerization of lactams, 53. Anionic polymerization of 2‐pyrrolidone accelerated with CO2, part 2
Authors: Brožek Jiří , Roda Jan , Králíček Jaroslav , Šanda Karel 
Published: April 2003

AbstractThe anionic polymerization of 2‐pyrrolidone (3) initiated with its potassium salt (1) (2‐oxo‐1‐pyrrolidinylpotassium) and carbon dioxide was studied under optimal conditions. On the basis of a detailed experimental analysis, it is suggested to consider the investigated polymerization in the presence of gaseous CO2 as an accelerated non‐activated polymerization. Alkali 2‐oxo‐1‐pyrrolidine carboxylate, which is formed in the system by reaction of CO2 with 1, probably does not take part directly in the polymerization process and excerts only a controlling role.
Chelation ion‐exchange properties of salicylic acid/thiourea/trioxane terpolymers
Authors: Manavalan Rajagopal , Patel Mohan M. 
Published: April 2003

AbstractTerpolymers prepared by condensation of salicylic acid and thiourea with trioxane in presence of acid catalysts, proved to be selective chelating ion‐exchange resins for certain metals. Chelation ion‐exchange properties of these terpolymers were studied for Cu2+, Ni2+, Fe3+, Mn2+, Co2+, Zn2+, and UO22+ ions. A batch equilibration method was employed in the study of the selectivity of metal ion uptake involving the measurement of distribution of a given metal ion between the polymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The terpolymers showed a higher selectivity for Cu2+, Fe3+, and UO22+ ions than for Mn2+, Co2+, and Zn2+ ions.
DSC analyses of bound water in the microdomains of interpolymer complexes
Authors: Ohno Hiroyuki , Shibayama Masashi , Tsuchida Eishun 
Published: April 2003

AbstractBound water in polymers and polymer complexes was analyzed quantitatively by means of differential scanning calorimetry in a temperature range from −50 to + 20°C. The water molecules were bound to the polymer chains with different strength, as reflected in a shift of the melting temperature. The existence of non‐freezing water was also confirmed from the relation between the incorporated water content and the heat of fusion. About 0,3 to 0,6 g of water was revealed to exist as non‐freezing water in 1,0 g of the polyelectrolyte complexes. This amount varied with the structure of the polymers investigated. The melting temperature of bound water increases with increasing water content of the component polymers or polymer complexes. The number of bound water molecules per monomeric unit of the polymer is about 3 to 7, and decreases by complex formation. It is speculated from the obtained results that desolvation is accompanied with complex formation, but the solvated state is maintained largely in spite of a drastic decrease in segmental motion of the polymer chains in the polymer complexes.
Polymers containing enzymatically degradable bonds, 8. Degradation of oligopeptide sequences in N‐(2‐hydroxypropyl)methacrylamide copolymers by bovine spleen cathepsin B
Authors: Rejmanová Pavla , Kopeček Jindřich , Pohl Jan , Baudyš Miroslav , Kostka Vladimír 
Published: April 2003

AbstractThree types of copolymers of N‐(2‐hydroxypropyl)methacrylamide(HPMA) were prepared which contain oligopeptide sequences: (a) HPMA copolymers containing oligopeptide side‐chains terminated with p‐nitroaniline; (b) soluble HPMA copolymers containing oligopeptide sequences in crosslinks connecting two poly(HPMA) chains; (c) a hydrophilic gel, i.e. a three dimensional copolymer of HPMA containing an oligopeptide sequence in the crosslinks. These polymeric substrates (suitable as drug carriers) containing potentially degradable oligopeptide sequences were incubated with an intracellular proteolytic enzyme, bovine spleen cathespin B. The degradation process of the substrates made it possible to reveal the relationship between the structure of oligopeptide sequences and their degradability. The results suggest an important role played by cathepsin B in the degradation of polymeric substrates investigated in this study under physiological conditions.
Determining the scope and impact of market orientation profiles on strategy implementation and performance
Authors: Dobni C. Brooke , Luffman George 
Published: April 2003

AbstractStrategy implementation and performance in organizations are influenced by its market orientation. Market orientation is the collective of employee behaviors that affects strategy implementation, how an organization interacts with its environment and adjusts to changes within that context. The relationship between market orientation, strategy implementation, and performance is robust across environmental contexts. This study identifies ideal behavioral profiles for organizations seeking to maximize performance by considering the scope and impact of market orientation on strategy implementation. This is accomplished by considering market orientation and strategy profiles in relation to performance in a holistic coalignment perspective, corresponding to competitive contexts characterized by varying degrees of market turbulence and competitive intensity. Important strategic and performance implications of this dynamic are revealed that should be considered by academics and practitioners alike. Copyright © 2003 John Wiley & Sons, Ltd.
Prenatal ultrasound diagnosis of fetal craniosynostosis
Authors: Delahaye S. , Bernard J. P. , Rénier D. , Ville Y. 
Published: April 2003

AbstractObjectiveCraniosynostosis is defined as the premature closure of the calvarial sutures. The prevalence of this heterogeneous condition is 1 in 2000 and approximately 100 different forms have been described with an established genetic transmission in half of them. Prenatal diagnosis of craniosynostosis relies mainly on identification of associated anomalies and molecular analysis of fetal DNA, which is only feasible in some syndromic forms and in well‐documented families. The objective of this study was to investigate the value of prenatal ultrasound examination of cranial sutures in fetuses at risk for craniosynostosis.MethodsForty fetuses at risk for craniosynostosis on the basis of either a family history (Group 1, n = 16) or skull deformity suspected on a first‐level fetal ultrasound examination (Group 2, n = 24) were retrospectively investigated. Craniosynostosis was suspected on the basis of skull deformities when present, however the diagnosis was only made in cases where there was a loss of hypoechogenicity of the normal sutures. All infants had both clinical and radiological investigations performed postnatally.ResultsIn Group 1, serial ultrasound examination from 12 weeks' gestation onwards led to accurate prenatal diagnosis in all 16 cases. Dysmorphism and skull deformity preceded closure of the sutures by 4 to 16 weeks. In Group 2, prenatal diagnosis was correct in 23/24 cases. There were no false‐negative results in either group.ConclusionsThis series questions further the uncertain genetic determinism of craniosynostosis and seems to rule out the hypothesis of a deformation sequence following primary closure of the cranial sutures. It also suggests that ultrasound examination is useful to demonstrate closure of the sutures in the third trimester of pregnancy in most affected cases. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Introduction to health economics for the medical practitioner
Authors: Kernick D P 
Published: April 2003

Abstract
Against a background of increasing demands on limited resources, health economics is exerting an influence on decision making at all levels of health care. Health economics seeks to facilitate decision making by offering an explicit decision making framework based on the principle of efficiency. It is not the only consideration but it is an important one and practitioners will need to have an understanding of its basic principles and how it can impact on clinical decision making. This article reviews some of the basic principles of health economics and in particular economic evaluation.
Effects of Losartan Titrated to Losartan/Hydrochlorothiazide and Amlodipine on Left Ventricular Mass in Patients with Mild-to-Moderate Hypertension
Authors: Martina B. , Dieterle T. , Weinbacher M. , Battegay E. 
Published: April 2003

To study the effects of the angiotensin II receptor antagonist Losartan and Amlodipine on left ventricular mass (LVM), we performed blood pressure measurements and transthoracic echocardiographies at baseline. After a 4-week placebo run-in period, 25 patients with mild-to-moderate essential hypertension were randomly allocated to active treatment with Losartan 50 mg titrated to Losartan 50 mg/hydrochlorothiazide (HCT) 12.5 mg (n = 11) or Amlodipine 5 mg titrated to 10 mg (n = 14) for 16 weeks. After treatment, blood pressure decreased significantly in both groups. LVM and LVM index (mean ± SD/median) in the Losartan group at baseline were 311 ± 101/288 g and 163 ± 55/150 g/m<sup>2</sup> and decreased significantly to 252 ± 25/255 g and 133 ± 22/128 g/m<sup>2</sup> (p = 0.003 for LVM; p = 0.01 for LVM index) after 16 weeks of active treatment. In the Amlodipine group LVM and LVM index decreased from 259 ± 47/243 g and 136 ± 25/ 131 g/m<sup>2</sup> to 240 ± 42/234 g and 126 ± 24/123 g/m<sup>2</sup> (n.s.). In conclusion, LVM decreased significantly as early as 16 weeks after initiation of antihypertensive treatment with the Angiotensin II antagonist Losartan.
Plasma Apolipoprotein B Levels Predict Platelet-Dependent Thrombosis in Patients with Coronary Artery Disease
Authors: Shechter Michael , Bairey Merz C. Noel , Paul-Labrador Maura J. , Shah Prediman K. , Kaul Sanjay 
Published: April 2003

Elevated plasma apolipoprotein B is a known risk factor for atherosclerotic coronary artery disease (CAD), however its relationship to arterial thrombosis is unexplored. We prospectively assessed apolipoprotein B and platelet-dependent thrombosis (PDT) in 42 CAD patients (37 men, 5 women, mean age 68 ± 9 years), by exposing porcine aortic media to their flowing unanticoagulated venous blood for 5 min using an ex vivo perfusion (Badimon) chamber. PDT was significantly correlated with apolipoprotein B (r = 0.41, p = 0.009), intracellular magnesium levels (r = –0.46, p = 0.003) fasting blood glucose (r = 0.47, p = 0.002), and total cholesterol (r = 0.43, p = 0.006). PDT did not correlate with serum total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoprotein A-I or fibrinogen levels. These findings suggest that the positive relationship of elevated apolipoprotein B to CAD may be, in part, related to its prothrombotic effects.
Monitoring of Extracellular Aspartate Aminotransferase and Troponin T by Microdialysis during and after Cardioplegic Heart Arrest
Authors: Kennergren Charles , Mantovani Vittorio , Lönnroth Peter , Nyström Britta , Berglin Eva , Hamberger Anders 
Published: April 2003

This study aims at developing per- and postopertive surveillance of the myocardium and focuses on ischemic damage following cardioplegic heart arrest. Levels of troponin T and total aspartate aminotransferase (ASAT) were analyzed in the myocardial interstitium of 10 patients with ischemic heart disease (IHD) who underwent coronary bypass surgery and in 12 patients with nonischemic heart disease (N-IHD) who underwent valvular surgery. Fluid from the myocardial interstitium of the anterior and the lateral wall of the heart was sampled by microdialysis probes that were implanted during surgery and extracted percutaneously 70–100 h later. There were no adverse reactions, and the equipment did not interfere with the surgical procedures. The peak in troponin T serum levels that occurred 4 h after cardiac arrest was preceded by a peak in troponin T levels in the microdialysates from the interstitium that occurred 1 h earlier. The concentration of troponin T in the microdialysate peak was 300 times higher than in the serum peak. The increase in serum ASAT levels during the first 7 h after cardiac arrest corresponded in time with a decrease in interstitial ASAT levels, which had already reached a maximum during cardiac arrest. The microdialysate/serum concentration ratio was considerably smaller for ASAT than for troponin T. Interstitial peak levels of troponin T correlated positively and significantly with peak levels of ASAT. Of the 22 patients, 15 had no postoperative events according to clinical outcome, ECG and serum tests. Fourteen of these had low to normal levels of interstitial ASAT and troponin T. Conversely, atrial fibrillation and/or premature atrial contractions were recorded in 8/22 patients, 7 of whom had elevated interstitial ASAT and/or troponin T concentrations in one or both of the sampled heart regions. The N-IHD patients had higher levels of troponin T in the interstitium 20–70 h following cardioplegia, while the peak levels did not differ between the groups. In conclusion, microdialysis sampling of troponin T and ASAT is safe and allows a highly sensitive analysis of the ischemic trauma exerted by the cardioplegic arrest.
Early Reperfusion Assessment and Repeated Thrombolysis in Acute Myocardial Infarction Estimated by Repeated Standard Electrocardiography
Authors: Gill Sabine , Haastrup Benedikte , Haghfelt Torben , Dellborg Mikael , Clemmensen Peter M. 
Published: April 2003

Thrombolytic therapy with streptokinase (SK) in acute myocardial infarction (AMI) does not result in early reperfusion in approximately 25% of patients. We hypothesized that early repeated thrombolysis with rt-PA in patients with early failed reperfusion would result in myocardial reperfusion. Fifty-nine AMI patients with a symptom delay of <6 h, treated with SK were included. ECG was taken on admission and after 90 and 180 min. An ST recovery of ≥25% at 90 min was interpreted as successful reperfusion. Sixteen patients had failed reperfusion at 90 min and were randomized to repeated thrombolysis with rt-PA or placebo. At 180 min from SK start, ST recovery was higher in the placebo group than in the rt-PA group (71 vs. 40%, p = 0.05). No serious bleeding complications were observed. Due to the limited sample size it was not possible to draw prominent conclusions.
Therapeutic Effects of an Injectable New Quinolone, Pazufloxacin, against Polymicrobial Infections in the Uterine Endometritis Model
Authors: Mikamo Hiroshige , Kawazoe Kyoko , Sato Yasumasa , Tamaya Teruhiko 
Published: April 2003

Polymicrobial infections with aerobes and anaerobes are common in female genital tract infections. We evaluated the efficacy of an injectable new quinolone, pazufloxacin, using a uterine endometritis model. Rats were infected with a mixed inoculation of <i>Escherichia coli</i> plus <i>Bacteroides fragilis</i> (MIC of pazufloxacin and ceftazidime: <i>E. coli:</i> 0.05 and 1.56 µg/ml, respectively, <i>B. fragilis:</i> 3.13 and 3.13 µg/ml, respectively). After inoculating 10<sup>7</sup> cfu/rat of each organism, pazufloxacin or ceftazidime (10 or 20 mg/kg, respectively, i.v., b.i.d., 3 days) was administered and compared with the nontreated group. The viable cell counts of the uterine corpus and uterine cervix in pazufloxacin-treated and ceftazidime-treated groups were decreased, compared with the nontreated group. The viable cell counts of the adnexa in the pazufloxacin-treated group were significantly decreased, compared with the ceftazidime-treated group. These results suggest that pazufloxacin would be useful for the treatment of polymicrobial infections, especially adnexitis.
Antifungal Activity of D0870 against Murine Infections and Its Mechanism of Action
Authors: Yamada Hidehiko , Tsuda Toshihiko , Watanabe Taiji , Kusakabe Satoshi , Mochizuki Hidenori 
Published: April 2003

We evaluated the in vivo antifungal activity of D0870, a new triazole agent, in comparison with that of fluconazole in two murine infection models. The therapeutic mechanism of D0870 in these models was also investigated in vitro. In a pulmonary infection with <i>Cryptococcus neoformans</i> in immunosuppressed mice, D0870 at 10–100 mg/kg significantly reduced viable counts in lungs infected with <i>C. neoformans</i> to 1/10–1,000 of the control on day 14, whereas fluconazole, only at 100 mg/kg, showed a significant reduction in the viable counts and was less active than D0870 at 10 mg/kg. D0870 at 3–30 mg/kg also showed excellent therapeutic efficacy against murine vaginal candidiasis and completely eliminated viable yeasts from the vaginal cavity, whereas positive cultures were found in 20% of mice treated with 30 mg fluconazole/kg. At pH 7 and 37°C, D0870 was active against <i>C. neoformans</i> in synthetic amino acid medium, fungal or sabouraud dextrose broth. By reducing the pH of the medium, the in vitro anticryptococcal activity of D0870 was enhanced and found to be fungicidal under all culture conditions at pH 4–5. D0870 also showed a stronger fungistatic activity against <i>Candida albicans</i> at pH 4. These results suggest that D0870 may exhibit a potent activity against these two murine infections by exerting an excellent antifungal activity at the infection sites thought to be acidic environments.