bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics and equilibrium of multicomponent adsorption on chiraly templated surfaces
Authors: Szabelski Paweł , Talbot Julian
Published: August 2004

In this contribution we propose a simple model of adsorption of a binary (racemic) mixture on a chiraly templated surface. As an example, the adsorption of a liquid mixture of enantiomers on a chiral stationary phase (CSP) is considered. In particular, we study the effect of the lateral interactions in the adsorbed phase on the kinetic and equilibrium isotherms of the enantiomers. Additionally, we investigate the influence of the composition of the surface on the performance of the CSP in the presence of the lateral interactions. To that end, the adsorption of the mixture is modeled by using Monte Carlo simulations as well as by applying an analytical approach involving rate equations coupled with the Mean Field Approximation (MFA). The predictions of the theory are found to be in good agreement with the results of the simulations. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1779–1786, 2004
Functional measurement of local proteolytic activity in living cells of invasive and non‐invasive tumors
Authors: Ludwig Thomas , Püttmann Sylvia , Bertram Helga , Tatenhorst Lars , Paulus Werner , Oberleithner Hans , Senner Volker
Published: August 2004

Proteolytic cleavage of extracellular matrix (ECM) and disruption of tissue architecture are fundamental features of tumor cell invasion. The proteolytic activity is focused in close proximity to the tumor cells. Here, we describe the possibility to quantify local proteolytic activity in the microenvironment of larger cell populations by the electrical resistance breakdown assay. The assay utilizes the transepithelial electrical resistance (TEER) of an epithelial monolayer as a sensitive indicator of monolayer integrity and permeability. Local destruction of ECM by single tumor cells was demonstrated by a second assay, based on a fluorescent matrix coating on cover slides. Local digestion of the matrix results in a reduction of fluorescence. Primary cells derived from high and low grade brain tumors as well as established cell lines of malignant gliomas and non‐neural tumors of different origin (melanoma, cervical carcinoma, and breast carcinoma) were compared. Differences in proteolytic activity between tumor entities were demonstrated in both assays. Primary cells of high grade gliomas and cell lines showed TEER breakdown and local matrix destruction, while low grade brain tumors lacked matrix disintegration and disruption of cell monolayers. Taken together, both assays are capable of demonstrating local proteolytic activity and thus are versatile tools for distinguishing high and low invasive tumor cells with a potential application as diagnostic and prognostic markers in clinical investigations. The advantage of the matrix digestion assay is the requirement of only very low tumor cell numbers, whereas measurement of TEER enables precise quantification of local proteolytic processes in large and even heterogeneous tumor cultures. © 2004 Wiley‐Liss, Inc.
Hypertrophy and transcriptional regulation induced in myogenic cell line L6‐C5 by an increase of extracellular calcium
Authors: De Arcangelis V. , Coletti D. , Canato M. , Molinaro M. , Adamo S. , Reggiani C. , Naro F.
Published: August 2004

Calcium plays a pivotal role in the establishment of the differentiated phenotype in myogenic cells but the involved molecular mechanisms are still matter of debate. Here we studied the effects of exposing L6‐C5 myogenic cells to high extracellular Ca2+ concentration ([Ca2+]o), which induces an increase of intracellular calcium ([Ca2+]i) without involving Ca2+ release from the intracellular stores but exclusively due to plasma membrane influx (Naro et al., ). Exposure of L6‐C5 cells to [Ca2+]o up to 20 mM for 30 min, before shifting them into a differentiative medium, induced the appearance of multinucleated, myosin‐positive myotubes, much larger than in control cells with an increased protein/DNA ratio. These large myotubes showed nuclear accumulation of the hypertrophy marker GATA‐2. The hypertrophic growth of these cells was blocked by cyclosporin A (CsA), FK506, or overexpression of a calcineurin‐dominant negative protein, suggesting the involvement in this process of the Ca2+ responsive phosphatase calcineurin. Furthermore, transient exposure of L6‐C5 cells to high [Ca2+]o increased the expression of luciferase reporter driven by myoglobin (Mb) and β‐MHC promoters but not IIB‐MHC and MCK promoters. Luciferase transcription driven by CK promoter was, instead, enhanced by mobilizing Ca2+ from the intracellular stores. These data indicate that a transient increase of [Ca2+]i due to plasma‐membrane influx is sufficient to induce a hypertrophic phenotype and an increased expression of slow‐fiber genes but not fast‐fiber genes. © 2004 Wiley‐Liss, Inc.
Nordihydroguaiaretic acid (NDGA) blocks the differentiation of C2C12 myoblast cells
Authors: Ito Hidenori , Ueda Hiroshi , Iwamoto Ikuko , Inaguma Yutaka , Takizawa Takenori , Asano Tomiko , Kato Kanefusa
Published: August 2004

Addition of nordihydroguaiaretic acid (NDGA) to the differentiation medium of C2C12 mouse myoblast cells caused severe inhibition of the formation of myotubes and suppressed differentiation‐dependent elevation in the levels of the creatine kinase M isozyme (CKM). Under these conditions, NDGA did not cause significant increase of damaged cells, as detected by annexin‐V‐FITC assay, or induction of heat shock proteins, known to be a response against extracellular stress. The results suggest that NDGA itself is not toxic but can effectively blocks the differentiation‐dependent increase of CKM during C2C12 differentiation. The levels of muscle specific bHLH proteins MyoD, Myf5, and myogenin were also decreased by addition of NDGA, indicating a block of the initial step of the myogenesis through downregulation of muscle specific genes. NDGA is known to be a lipoxygenase inhibitor but other examples, like MK‐886 and CDC, did not exert the same effects on differentiation of muscle cells, indicating that mechanisms of NDGA action are independent of its influence on lipoxygenase. © 2004 Wiley‐Liss, Inc.
Inducible reproductive plasticity of the guppy Poecilia reticulata in response to predation cues
Authors: Dzikowski Ron , Hulata Gideon , Harpaz Sheenan , Karplus Ilan
Published: August 2004

Predation has long been described as one of the major driving forces in evolution. Guppies (Poecilia reticulata) from natural populations exposed to different predation pressures, were found to have different life history traits. Reproductive plasticity in response to direct predation cues has mainly been reported for invertebrates. The goals of the present study were to determine whether exposure to predation cues would induce reproductive phenotypic plasticity in female guppies and to determine whether the effective cues are visual, chemical, or a combination of both. In our first experiment, female guppies exposed to predation cues of the african cichlids Aulonocara nyassae increased their reproductive output by almost two fold, having larger brood‐sizes and shorter brood‐interval at the first spawn. This effect disappeared in the second spawn in the absence of predators. In the second experiment we found that exposure to the predators induced an increase in the brood‐size regardless of whether the cue was: only visual, only chemical, visual and chemical or visual, chemical and tactile. The impacts of these cues were equally powerful on the tested variables and they did not have any cumulative effect. Similar to the results of the first experiment, this effect disappeared in the second spawn, in the absence of predation cues. The present study demonstrates a direct immediate and reversible effect of predation cues on guppy reproduction. J. Exp. Zool. 301A:776–782, 2004. © 2004 Wiley‐Liss, Inc.
Nucleotide and protein sequences of a proteinase inhibitor from the vitelline envelope of dace (Tribolodon hakonensis) eggs
Authors: Hosomi Osamu , Ohe Yoshihide , Takeya Akira , Hosaka Kohei , Okubo Toyoji , Iyobe Shizuko , Kudo Shigeharu
Published: August 2004

Our experimental purpose is to probe the structure(s) of the chorionic proteinase inhibitor and its cDNA sequence(s) and to develop the application of safe medicines for protection of human and other animal bodies from pathogenic microbe attacks. In this study, chorionic proteinase inhibitor protein was isolated, sequenced and used to base the design of PCR primers, which were then used to amplify DNA using RT‐PCR. A cDNA clone of the protein which inhibited the activities of serine proteinases and thermolysin was obtained on the basis of mRNA extracted from ovarian tissue of dace,Tribolodon hakonensis, and the deduced amino acid sequence was determined. Chorionic proteinase inhibitor (TribSPI) peptides of about 9.0 kDa (TribSPI) and 14 kDa (TribSPI‐S) were purified from vitelline envelope extracts by thermolysin‐immobilized affinity‐chromatography. The cloned TribSPI cDNA was 1,806 bp in length, and the open reading flame (ORF) was 915 bp encoding a protein of 305 amino acid residues. The inhibitor protein had a molecular mass of 33,550 daltons and was composed of five similar domains. Each domain contained eight cysteine residues, and it's deduced amino acid sequence was only 33≈34% identical to those of human and porcine antileukoproteinases (hALP and pALP, respectively). A possible binding‐site for serine proteinases, Arg‐Ile, was contained in three domains.J. Exp. Zool. 301A:756–766, 2004.© 2004 Wiley‐Liss, Inc.
Na+/H+ Exchanger‐3 is involved in mouse blastocyst formation
Authors: Kawagishi Rikako , Tahara Masahiro , Sawada Kenjiro , Morishige Kenichiro , Sakata Masahiro , Tasaka Keiichi , Murata Yuji
Published: August 2004

The mouse blastocyst consists of the trophectoderm, the inner cell mass, and a fluid‐filled cavity, the blastocoel. Formation and subsequent expansion of this cavity is important for further differentiation of the inner cell mass and successful implantation. Previous work provided evidence that vectorial transport of Na+ and Cl− ions through the trophectoderm into the blastocoel generates an osmotic gradient that drives fluid across this epithelium. As the activity of the Na+/H+ exchanger (NHE) has been implicated as the exchanger responsible for facilitating the transtrophectodermal Na+ flux, the functional role of NHE in mouse blastocoel development was determined. Embryos were cultured in the presence of subtype‐specific NHE inhibitors to examine the role of NHEs in blastocoel development. When 2‐cell stage embryos were treated continuously with a specific inhibitor of NHE‐1, cariporide, the embryos passed beyond the 8‐cell stage and became blastocysts. However, in the presence of a specific inhibitor of NHE‐3, S3226, the 2‐cell stage embryos developed to the morula stage but formation of the blastocyst were inhibited in a dose‐dependent manner. Cariporide did not inhibit the formation of the blastocoel cavity from the morula stage whereas S3226 did inhibit that process. S3226 also reduced the rate of re‐expansion of blastocysts collapsed by cytochalasin D upon transfer to the control medium. An immunofluorescence study showed that NHE‐3 was detected in the vicinity of the cell membrane of the trophectoderm, especially in the apical cell margins of the trophectoderm. These results suggest that NHE‐3 is likely involved in blastocyst formation. J. Exp. Zool. 301A:767–775, 2004. © 2004 Wiley‐Liss, Inc.
Seminal vesicle secretion of African catfish, its composition, its behaviour in water and saline solutions and its influence on gamete fertilizability
Authors: Mansour Nabil , Lahnsteiner Franz , Patzner Robert A.
Published: August 2004

The seminal vesicle secretion (SVS) of the African catfish, Clarias gariepinus, was investigated by analytical and experimental methods. SVS consists mainly of proteins and glycoproteins which are responsible for its viscous and sticky nature. The secretion contains also high activities of acid phosphatase, alkaline phosphatase, and proteases. These catabolic enzymes do not have functions in autolysis or liquefaction of SVS but are considered to eliminate aging spermatozoa from the proximal portions of seminal vesicle and from the spermatic duct. SVS of the African catfish is unstable in the environment relevant for natural spawning. When SVS was mixed with water, seminal plasma or different types of saline solutions its protein coagulated forming fibrous or granular particles of variable size within a few seconds. Pure SVS completely inhibited the motility as the sticky secretion hindered spermatozoa in free swimming. SVS had also a negative effect on sperm fertility, egg fertility, and sperm egg contact, as the fertilization was drastically suppressed in the presence of SVS. Basing on our analytical and experimental results we exclude that SVS has functions in stabilizing the viability of spermatozoa stored in the spermatic ducts or is an energy resource of spermatozoa. It also does not improve or stabilize the fertilization process and has no functions in adhering the eggs to substrates or in covering the eggs for mechanical protection or antibacterial defense. A function of SVS in the male and female communication during the prenuptial spawning behaviour is discussed. J. Exp. Zool. 301A:745–755, 2004. © 2004 Wiley Liss, Inc.
Diurnal rhythm and effect of temperature on oxygen consumption in earthworms, Amynthas gracilis and Pontoscolex corethrurus
Authors: Chuang Shu Chun , Lee Hsinyu , Chen Jiun Hong
Published: August 2004

Different species of earthworms show distinct patterns of oxygen consumption pattern. Amynthas gracilis has a diurnal rhythm of oxygen consumption, consuming more oxygen at night, whether being incubated at 20, 25, or 30°C. The higher oxygen consumption of A. gracilis is directly related to its behavior, as it shows higher activity at night. In contrast, Pontoscolex corethrurus showed no obvious diurnal rhythms of oxygen consumption or behavior. In addition, its oxygen demand is not related to temperature. A. gracilis has higher oxygen consumption than P. corethrurus at 20 and 30°C. The difference in temperature adaptation of oxygen consumption between these two species may be a strategy by which earthworms adapt to different temperatures. This might explain why A. gracilis disperses on the soil surface at night after a rain, in contrast to P. corethrurus for which such behavior was not been observed. J. Exp. Zool. 301A:737–744, 2004. © 2004 Wiley Liss, Inc.
The negative effects of positive stereotypes: ethnicity‐related stressors and implications on organizational health
Authors: Cocchiara Faye K. , Quick James Campbell
Published: August 2004

Racism and discrimination are known causes of stress for ethnic minorities. While negative stereotypes may adversely impact health and performance in racial groups, we suggest that positive performance stereotypes may also have adverse effects. Therefore, the preventive management of performance stereotypes through effective coping can improve organizational health. In addition, studies of coping within racial groups aimed at understanding within group variance can lead to the identification of positive coping methods for ethnic minorities. Copyright © 2004 John Wiley & Sons, Ltd.
Do birds of a feather shop together? The effects on performance of employees' similarity with one another and with customers
Authors: Leonard Jonathan S. , Levine David I. , Joshi Aparna
Published: August 2004

Theories have suggested that employee diversity can affect business performance both as a result of customer preferences and through changes of relations within the workplace. We examine these theories with data from more than 700 retail stores employing over 70 000 individuals, matched to census data on the demographics of the community. While past theories predict that increasing the similarity between employees and customers will increase sales, we find no consistent relationship. The exception is that Asian employees appear to be most productive when many nearby residents are Asian immigrants who do not speak English. Diversity of gender and race within a store had no important effect on sales, while age diversity predicted lower sales. Copyright © 2004 John Wiley & Sons, Ltd.
Differences in retention of dioxin‐like compounds and organochlorinated insecticides on an immunochromatographic column. Interpretation and applicability
Authors: Concejero Miguel Angel , Abad Esteban , Rivera Josep , Herradón Bernardo , González María José , de Frutos Mercedes
Published: August 2004

The retention of organochlorinated compounds on an immunochromatographic column is studied. The compounds considered are usually found together in real samples of environmental concern, and include chlorinated biphenyls, chlorinated dibenzo‐p‐dioxins, chlorinated dibenzofurans, and organochlorinated insecticides. The different retention observed for different compounds is interpreted in light of the structural similarities of the compound studied with that used as a hapten to raise the antibodies employed as ligands in the immunochromatographic column. Differences in retention of the organochlorinated compounds on the immunocolumn make it possible to fractionate them. Mixtures of phosphate buffer solution and ACN in different ratios were used as desorption agents. Depending on the percentage of ACN employed, different fractionations of the organochlorinated compounds are obtained. The use of 20% ACN allows fractionation of most insecticides from chlorinated biphenyls, dioxins, and furans. Besides, chlorinated biphenyls of different chlorination degree can be separated. Moreover, pentachlorinated dioxins and pentachlorinated furans are separated from hexachlorinated biphenyls. Fractionation is of critical importance from a practical point of view, as it avoids some of the interferences that otherwise take place during the subsequent gas chromatography/mass spectrometry (GC/MS) analysis of these compounds. In this way, immunochromatography makes it possible to perform in a single step all the processes (extraction, clean‐up, concentration, and fractionation) that are needed prior to the GC/MS analysis of these analytes in aqueous samples. An additional advantage of this method is the reusability of the immunoaffinity chromatography column for more than 500 times.
Front Cover: Macromol. Rapid Commun. 16/2004
Authors: Goto Hiromasa , Akagi Kazuo
Published: August 2004

Front Cover: An image of an optically active poly(3,4‐ethylenedioxythiophene) (PEDOT*) film prepared by an electrochemical polymerization method in a chiral nematic liquid crystal field is shown. The chiral nematic liquid crystal used here provides a sequential chiral pattern as a molecular mold during the polymerization, and the polymer grows in the three‐dimensional chiral field to form a one‐handed helical structure. This simple method provides a new technique for preparing chiral conducting films in a thermotropic chiral liquid crystal field.

Further details can be found in the Communication by H. Goto and K. Akagi* on page 1482.
Eine elastisch‐plastische Übergangsbedingung für die Tropfenschlagerosion von Gesteinen und Betonen
Authors: Momber A. W.
Published: August 2004

Mineralische Werkstoffe verhalten sich beim Verschleiß durch aufschlagende Flüssigkeitstropfen je nach Beanspruchungsregime und Werkstofftyp elastisch oder elastisch‐plastisch. Eine einfache Verhältniskennzahl, die Bruchzähigkeit und Druckfestigkeit (bzw. Vickers‐Härte) kombiniert, gestattet jedoch bei vorgegebenem Beanspruchungsregime eine vorläufige Einordnung der Materialien. In herkömmlichem Sinne „harte”︁ Werkstoffe, wie Granit und Feldspate, weisen niedrige Verhältniswerte bzw. hohe Härtewerte auf und verhalten sich elastisch, während in herkömmlichem Sinne „weiche”︁ Werkstoffe, wie Kalkstein, Mörtel und Schiefer, die elastisch‐plastisch reagieren, durch hohe Verhältniswerte und niedrige Härtewerte charakterisiert werden können.
Gibt es eine Universalkerbkontur nach dem Vorbild der Natur?
Authors: Mattheck C. , Bethge K. , Tesari I. , Scherrer M. , Kraft O.
Published: August 2004

Kerbspannungen sind Biegespannungen, die sich als Folge der Deformation der Kerbkontur den Nennspannungen überlagern (Abb. 1 u. 2). Diese duale Natur der Gesamtspannung macht es möglich Kerben so auszuformen, dass die überlagerten Biegespannungen so ansteigen wie die Nennspannungen abfallen. Damit ist die Gesamtspannung entlang der Kontur konstant, keine Spannungskonzentration, keine Sollbruchstellen, lange Lebensdauer ohne Ermüdungsbruch! Was bisher durch Computersimulation des lastgesteuerten Wachstums der Bäume mittels der CAO‐Methode (Computer Aided Optimization) [1,2] nur auf Finite‐Elemente‐Basis möglich war, geht jetzt mit Taschenrechner, ja sogar mit einem Handy das Tabellenkalkulation kann!

Wem auch das zuviel Aufwand ist, der nehme einen Zirkel und ein 45°‐Zeichendreieck.

Die optimierten Kurven ähneln sich für viele Fälle verblüffend, fast könnte man meinen, es gäbe für bestimmte Bedingungen eine Universalkerbkontur. Schwingversuche mit drastisch höheren Versagenslastspielzahlen lassen uns hoffen!
Neuronal differentiation‐induced change in expression of neurotrophic factor genes in adrenal chromaffin cell line tsAM5D expressing temperature‐sensitive SV40 T‐antigen
Authors: Murata Tomiyasu , Tsuboi Masaru , Hikita Kiyomi , Kaneda Norio
Published: August 2004

We recently established adrenal medullary cell line tsAM5D, immortalized with a temperature‐sensitive mutant of the oncogene simian virus 40 large T‐antigen. When cultured with basic fibroblast growth factor (bFGF) and ciliary neurotrophic factor (CNTF), tsAM5D cells proliferated at the permissive temperature (33°C) for the expression of the oncogene and differentiated into neuron‐like cells at the nonpermissive temperature (39°C). In the present study, we investigated the gene expression of several neurotrophic factors associated with the neuronal differentiation induced by the temperature shift. Using real‐time RT‐PCR analysis on bFGF and CNTF‐treated cells, we found up‐regulated expression of mRNAs for bFGF, leukemia inhibitory factor, transforming growth factor (TGF)‐β2, persephin, acidic fibroblast growth factor, neurotrophin‐3, preproenkephalin, and TGF‐β1 and down‐regulated expression of the mRNAs for interleukin‐6, neurturin, and CNTF. No apparent differences were observed in the mRNA level of insulin‐like growth factor‐2, TGF‐β3, and neurotrophin‐4/5. These results suggest that the regulated expression of neurotrophic factor genes play an important role in the neuronal differentiation of tsAM5D cells.
Calexcitin‐like immunoreactivity in the pond snail Lymnaea stagnalis
Authors: Hatakeyama Dai , Inamura Satoko , Ito Etsuro , Sakakibara Manabu , Nelson Thomas J. , Alkon Daniel L.
Published: August 2004

Calexcitin (CE) is a low molecular weight Ca2+‐ and guanosine triphosphate‐ binding protein, which is phosphorylated during associative learning in both vertebrates and invertebrates. The purpose of this study was to determine the presence of CE in the central nervous system (CNS) of the pond snail Lymnaea stagnalis, which can acquire classical and operant conditioning. Immunoblotting of CE showed that the anti‐CE antibody prepared from squid can detect Lymnaea CE. In the cerebral ganglia, CE‐like immunoreactivity was exhibited in two pairs of cell clusters that receive taste signals from the superior or median lip nerves. In both pedal ganglia, CE‐like immunoreactivity was detected in 1‐4 cell of the PeA clusters, which are involved in the withdrawal response. Our results therefore showed that CE is involved in the feeding and withdrawal neural networks, suggesting that CE may function in associative learning of feeding and withdrawal behavior in L. stagnalis.
Attenuated noradrenaline release in the paraventricular nucleus are induced by electrical and angiotensin II activation of the subfornical organ in estrogen‐treated rats
Authors: Tanaka Junichi , Miyakubo Hiroko , Fujisawa Shigeko , Nomura Masahiko
Published: August 2004

Previous studies have demonstrated that estrogen alters the responsiveness of subfornical organ (SFO) neurons projecting to the hypothalamic paraventricular nucleus (PVN) to angiotensin II (ANG II) and activation of the SFO facilitates noradrenaline (NA) release in the PVN area. The present study was carried out to investigate whether estrogen elicits alterations in the NA release in the PVN area induced by electrical and chemical activation of the SFO. Intracerebral microdialysis techniques were utilized to quantify the extracellular content of NA in the region of the PVN in ovariectomized (OVX) female rats that were treated with either propylene glycol (PG) vehicle or estradiol benzoate (EB). In both groups, electrical stimulation (5–20 Hz, 600 μA) of the SFO significantly increased the NA concentration in the PVN area. Injections of ANG II (10–8 M, 0.2 μl) into the stimulation site significantly enhanced the release of NA in the PVN area. The NA release to either electrical or chemical stimulation of the SFO was much greater in the PG‐treated than in the EB‐treated rats. These results suggest that estrogen may decrease the NA release in the PVN area caused by ANG II acting at the SFO.
Risk of venous thromboembolism in pediatric patients with brain tumors
Authors: Tabori Uri , Beni‐Adani Liana , Dvir Rina , Burstein Yoav , Feldman Zeev , Pessach Itai , Rechavi Gideon , Constantini Shlomi , Toren Amos
Published: August 2004

Background

Venous thromboembolism (VTE) is a common event in adults with malignant brain tumors approaching 24% throughout the course of the disease. The high morbidity and mortality of this complication yielded several protocols for prevention of the disease in adults undergoing neurosurgery for brain tumors and possible primary prevention afterwards. We investigated the incidence and complications of VTE in pediatric neuro‐oncology patients.

Procedure

We analyzed, retrospectively, the files of all consecutive patients under the age of 18 years who were hospitalized for the treatment of brain tumors between the years 1990 and 2003 in two leading, closely related, Israeli neuro‐oncology centers.

Results

A total of 462 children were analyzed. Three hundred eighty‐four patients underwent surgery and 78 were treated medically. Only three (0.64%) of the patients developed clinical episodes of VTE that were treated conservatively. Two of these patients developed intracranial bleeding while on secondary prevention for the disease.

Conclusions

Although this study has considerable limitations in terms of retrospective design, heterogeneous group of patients and diagnoses, the changing awareness for thrombosis over the last 14 years and the inclusion of symptomatic VTE events only, our surprising data suggest that, as opposed to adults, the risk of clinically significant VTE in children with brain tumors may be exceedingly low. These findings set the stage for future forthcoming evaluations in view of the prospective studies that were done in adults and the possible significant implications for the prevention and possible etiologies of the disease. © 2004 Wiley‐Liss, Inc.
Nonadherence as a predictor of antidiabetic drug therapy intensification (augmentation)
Authors: Kogut Stephen J. , Andrade Susan E. , Willey Cynthia , Larrat E. Paul
Published: August 2004

Purpose

To determine if nonadherence with antidiabetic drug therapy is predictive of subsequent antidiabetic drug therapy intensification.

Methods

We conducted a retrospective cohort study examining retail pharmacy dispensings of sulfonylureas or metformin to 1067 patients having diabetes. Patients that did not receive a sufficient quantity of medication to cover at least 80% of days during the evaluation period were classified as nonadherent. Outcomes identified were increase in the dose of antidiabetic medication utilized, the addition of a second antidiabetic agent to the regimen or either.

Results

Among users of sulfonylurea monotherapy, those classified as nonadherent were 45% more likely to intensify therapy in subsequent months as compared with those classified as adherent (age‐adjusted odds ratio (OR) 1.45; 95% confidence interval (CI) 1.06–2.00). This finding was largely driven by observed increases in dosage, which were more likely among patients classified as nonadherent (age‐adjusted OR 1.48, 95%CI 1.07–2.05). Nonadherence was not found to be predictive of the subsequent addition of a second antidiabetic agent (OR 1.02; 95%CI 0.64–1.63). Overall findings were similar for the smaller sample of patients receiving metformin monotherapy, though observed differences did not achieve statistical significance.

Conclusions

Patients who were poorly adherent to oral antidiabetic drug therapy more frequently experienced an increase in the dose of medication prescribed, as compared to patients that were classified as adherent. This finding underscores the need for prescribers to consider nonadherence as a root cause when patients fail to achieve therapeutic goals. Copyright © 2004 John Wiley & Sons, Ltd.
Indentation of poly(formaldehyde), reinforced nylons and poly(ethyl terephthalate)
Authors: Benabdallah H. S. , Bui V. T.
Published: August 2004

Indentation tests were performed on flat coupons of poly(formaldehyde), three types of reinforced nylon and reinforced poly(ethyl terephthalate) using a device developed for a typical universal tensile testing machine. Spherical, conical and cylindrical indenters were selected for this study and the effects of indenter shape combined with the rate of indentation on the behavior of these materials were examined. The load‐depth relationship during the indentation process revealed the emergence of step‐like transitions at high indentation rates. The effects of the assessed parameters on the indentation resistance, as defined in this study, were analyzed. Interest was also focused on the investigation of the deformation work as well as the plastic work taking place for a total depth that incorporated both the skin and part of the bulk of the material. The modeling of the data was based on a previously developed approach and the introduction of a modified parameter that took not only the geometrical characteristics of the indenter into account but also the indentation depth. The proposed method has proven to be useful since a steady state of the indentation pressure was observed for all materials after a certain depth of indentation. This was valid for the results obtained using both conical and cylindrical indenters. Polym. Eng. Sci. 44:1439–1447, 2004. © 2004 Society of Plastics Engineers.
Mechanical and erosion properties of CaCO3‐EMAA thermal sprayed coatings
Authors: Yan F. Y. , Gross K. A. , Simon G. P. , Berndt C. C.
Published: August 2004

Polymer‐ceramic composite coatings manufactured from calcium carbonate and ethylene‐methacrylic acid copolymer (EMAA) were prepared via a thermal spray process employing different CaCO3 filler sizes (average size of 2.8, 9 or 36 μm) and loading levels from about 2.5 to 7 wt%. The optimum filler feeding characteristics, deposition efficiency and deposition rate were obtained with a 36 μm sized CaCO3. Tensile properties, peel strength, and the erosion resistance of a pure EMAA and CaCO3‐EMAA composite coatings were investigated. It was found that the tensile strain at fracture of the composite coating decreased with the addition of filler to a greater degree than that observed in compression‐molded polymer composites. This is attributed to an inhomogenous distribution of the filler, with more being concentrated at the boundaries of the deposited polymer particles, thereby establishing a rigid framework within the coating. Only a small filler content is necessary to establish large changes in the mechanical properties of the coating. The peel strength of a composite coating decreases with filler content, both on a mild steel substrate and a previously sprayed polymer coating. Bonding to the latter is significantly higher and offers a possibility as a bonding layer between substrates and composite coatings. The coefficient of friction is lowered with the addition of a filler. Erosion testing has shown that the erosion resistance of PF111 is little improved overall with filler addition, although some increase is found for filler contents less than 5 vol%. Polym. Eng. Sci. 44:1448–1459, 2004. © 2004 Society of Plastics Engineers.
An axisymmetric model for thread forming in polycarbonate and polypropylene screw and boss fasteners
Authors: Ellwood Kevin R. J. , Fesko Don , Bauer David R.
Published: August 2004

Plastic boss and screw fasteners are an economical means of securing automotive components, such as instrument or body panels. However, new materials and/or suboptimal design present challenges to the boss/screw effectiveness. Failure of a boss/screw can result is loss of functional performance or increased squeak and rattle. Failure is often controlled by what occurs during the initial thread‐forming process. Thus, the goal of this paper is to develop an FEA model to elucidate the thread‐forming process so that we can facilitate subsequent design and/or process optimization, and understand potential failure modes. The FEA must accommodate nonlinear couplings, such as large strain and heat transfer. Heat generation is present in the forms of interfacial shear heating and plastic work associated with the large deformation of the interface between the boss and screw. Strain rate‐dependent materials are included using the Eyring theory for plastic flow of polymeric materials. Results of the model are presented and compared to experimentally determined torque curves and temperatures. Polym. Eng. Sci. 44:1498–1508, 2004. © 2004 Society of Plastics Engineers.
Effect of ultrasound on extrusion of PP/EPDM blends: Structure and mechanical properties
Authors: Chen Yingzi , Li Huilin
Published: August 2004

The effects of ultrasonic irradiation on the mechanical properties, morphology, and crystal structure of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) blends were examined. Results show that appropriate irradiation intensity can noticeably increase the toughness of the PP/EPDM blends without reducing rigidity. Scanning electron microscopic (SEM) observation shows that with ultrasonic irradiation, the morphology of a well‐dispersed EPDM phase is formed in the PP/EPDM blend. The glass transition temperatures of PP and EPDM phase approach each other as a result of ultrasonic irradiation. Differential Scanning Calorimetric (DSC) analysis indicates that the crystallinities of the PP and EPDM phases increase with ultrasonic irradiation, and β crystals of PP form in the PP/EPDM blend with ultrasonic irradiation, which is proven by wide angle X‐ray diffraction (WAXD) analysis. Polym. Eng. Sci. 44:1509–1513, 2004. © 2004 Society of Plastics Engineers.
Determination of the phase transition behavior of thermoplastic polyurethanes from coupled rheology/DSC measurements
Authors: Nichetti Dario , Grizzuti Nino
Published: August 2004

The rich behavior of thermoplastic polyurethanes (TPUs) undergoing phase transition is investigated by means of combined rheological and DSC techniques. In particular, the kinetics of micro‐phase transition of a commercial TPU are followed under both isothermal conditions (crystallization from the melt), and constant temperature rate heating ramps (melting). In rheological tests, the time evolution of the storage modulus is monitored by using a strain rate–controlled rheometer. The rheological results are compared with those obtained by more traditional calorimetric techniques (DSC) under the same thermal histories. It is shown that rheological measurements can give additional (and, in some cases, more accurate) information than that obtained from the more classical thermal analysis. Polym. Eng. Sci. 44:1514–1521, 2004. © 2004 Society of Plastics Engineers.
The thermomechanical environment and the mechanical properties of injection moldings
Authors: Viana Júlio C. , Billon Noelle , Cunha António M.
Published: August 2004

Axisymmetric specimens were injection molded in a propylene copolymer with systematic variations of the melt and mold temperatures and the injection flow rate, in a total of 15 different processing conditions. From computer simulations of the mold filling stage using commercially available software packages, two thermomechanical indices were calculated. They aim at evaluating the level of orientation of the skin and the degree of crystallinity of the core layers. Assuming that these morphological features determine the mechanical response of the moldings, the thermomechanical indices were weighted by the relative thickness of the skin and core layers. The tensile behavior of the moldings was assessed at two velocities of 3.3 × 10−5 (2 mm/min) and 3 m/s. The mechanical properties studied were the initial modulus, the yield stress and the strain at break. The relationships between the weighted thermomechanical indices and these mechanical properties were analyzed from 3D response surfaces obtained by polynomial fittings. Globally, a marked effect of the strain rate on the mechanical response along with a distinct sensitivity on the weighted thermomechanical indices was found. At high strain rates the microstructural differences were enhanced. The dependence of the yield stress on the thermomechanical indices was not significantly affected by the strain‐rate. However, the strain‐rate dependence of the other mechanical properties was strongly influenced by the initial microstructural state. Furthermore, the maximization of different mechanical properties could not be made simultaneously due to their distinct microstructural dependences. The concept of the thermomechanical indices is evidenced as a simple, valid and valuable tool to establish straightforward relationships between the processing and the mechanical behavior. Polym. Eng. Sci. 44:1522–1533, 2004. © 2004 Society of Plastics Engineers.
Investigation of morphology formation in SBS block copolymer/homopolystyrene blends
Authors: Huy T. A. , Adhikari R. , Lüpke Th. , Michler G. H. , Knoll K.
Published: August 2004

Polymer blends comprising a polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) block copolymer and atactic homopolystyrene (hPS) were investigated using injection molded and solution cast samples. The morphology of the materials was studied by means of transmission electron microscopy (TEM) and scanning force microscopy (SFM). Dynamic mechanical analysis (DMA) was used to characterize the phase behavior and the morphology formation of the block copolymer as well as of the SBS/hPS blends. The glass transition temperatures seem to strongly depend on the homogeneity of the corresponding phases. A distinct difference was found between the morphologies of the blends prepared by different methods. While the SBS block copolymer always shows a lamellar morphology in injection molded or as‐cast samples, the injection molded blends show a disturbance in the morphology consisting of alternating layers. In contrast, in the case of as‐cast samples, added hPS forms polystyrene domains dispersed in a matrix of the pure block copolymer. Regarding the change in the glass transition temperature, in the effective volume and in the interfacial volume obtained from DMA curves, the morphology formation of the injection molded samples (pure SBS block copolymer and the corresponding blends) was investigated. Two different structural models for the blends are proposed. Polym. Eng. Sci. 44:1534–1542, 2004. © 2004 Society of Plastics Engineers.
Injection molded automotive TPO—a multilayer composite structure of varied orientations
Authors: Strebel J. J. , Mirabella F. , Blythe C. , Pham T.
Published: August 2004

Orientation in injection molded polypropylene tensile bars was examined by microscopic and infrared dichroism methods. These methods were then applied to tensile bars molded from TPOs. The injection molded parts were shown to have up to five distinct layers of varying orientation between the outer edge and the center of the sample. In both the polypropylene and TPO formulations, the skin thickness of the moldings increased as the polymer molecular weight increased. A unique, highly oriented region occurred in the core of TPO samples, in contrast to the reduced orientation observed in parts made of propylene homopolymer. The visual observations made from optical photomicrographs were successfully correlated with quantitative orientation data determined by infrared microspectroscopy. Polym. Eng. Sci. 44:1588–1593, 2004. © 2004 Society of Plastics Engineers.
Analysis of the creep behavior of polypropylene‐woodflour composites
Authors: Nuñez Adrián J. , Marcovich Norma E. , Aranguren Mirta I.
Published: August 2004

The creep behavior of composites prepared from woodflour and polypropylene has been analyzed. The woodflour content was varied from 0% to 60%. The compatibility between filler and matrix was varied by adding a non‐commercial polypropylene‐maleic anhydride copolymer (PPMAN) to the mixture. Short‐term and long‐term creep tests of woodflour/polypropylene composites at different temperatures were carried out. The effects of filler content, addition of compatibilizing agent and temperature were discussed. The creep deformation was generally reduced with woodflour addition, except at very high filler concentrations because of filler‐wetting and dispersion problems. Low temperatures and addition of PPMAN also reduced the creep deformation. The creep compliance was modeled using the Bürgers model and a power law equation. The parameters were found from the best fitting of experimental data using an optimization method. The Bürgers model was found to provide a good description of the linear viscoelastic behavior. The mathematical description obtained from the short‐term creep was utilized to predict the dynamic mechanical behavior of the composites with very good agreement between experimental and calculated values. Attempts to use the time‐temperature‐superposition principle to predict long‐term creep from high temperature results were not successful because of the aging of the samples during creep at low temperatures. However, there was a good superposition of the short‐term and long‐term data at temperatures close to 70°C–80°C. The reason for this behavior is a relaxation of the PP matrix that takes place in that temperature range and erases any previous aging of the material. Polym. Eng. Sci. 44:1594–1603, 2004. © 2004 Society of Plastics Engineers.
Influence of electronic effect on catalytic activity of salicylaldiminato nickel(II) complexes
Authors: Zhang Tianzhu , Guo Dawei , Jie Suyun , Sun Wen‐Hua , Li Ting , Yang Xiaozhen
Published: August 2004

A means of correlation between the activity and the net charge, the metal atom net charge correlation (MANCC), which was successful in the activity prediction of the early‐transition metal catalysts, has been used to study the catalytic activities of salicylaldiminato Ni(II) complexes, the late‐transition metal catalysts, in olefin polymerization or oligomerization. A comparison with the available quantum mechanics/molecular mechanics (QM/MM) calculation data suggests that even without a detailed mechanism, MANCC results mostly agree with QM/MM calculation data regarding insertion barrier data and enthalpy change. Eight experimental complexes were further built up by modeling; their catalytic activities predominantly increased in line with the net charges on the metal atoms. The same results were obtained for the other four complexes synthesized in the present work. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4765–4774, 2004
Preparation of magnetic polystyrene latex via the miniemulsion polymerization technique
Authors: Csetneki I. , Faix M. Kabai , Szilágyi A. , Kovács A. L. , Németh Z. , Zrinyi M.
Published: August 2004

Magnetic iron oxide (magnetite, Fe3O4) nanoparticles were encapsulated with polystyrene to give a stable water‐based magnetic polymer latex, using the miniemulsion polymerization technique. The resulting magnetic latexes were characterized with transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometer measurements (VSM), and 57Fe Mössbauer spectroscopy measurements. TEM revealed that all magnetite nanoparticles were embedded in the polymer spheres, leaving no empty polystyrene particles. The distribution of magnetite particles within the polystyrene spheres was inhomogeneous, showing an uneven polar appearance. The DLS measurements indicated a bimodal size distribution for the particles in the latexes. According to our magnetometry and Mössbauer spectroscopy data, the encapsulated magnetite particles conserve their superparamagnetic feature when they are separated in the polymer matrix. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4802–4808, 2004
Synthesis and characterization of oxidized cellulose
Authors: Zimnitsky Dmitry S. , Yurkshtovich Tatiana L. , Bychkovsky Pavel M.
Published: August 2004

Samples of oxidized cellulose (OC) with various carboxyl contents and degrees of crystallinity were obtained by the oxidation of native and mercerized cellulose with a solution of nitrogen(IV) oxide in CCl4. A detailed characterization of these OC samples was performed. The effect of oxidation conditions (concentration of N2O4 in the solution and oxidation time) and starting cellulose material on OC characteristics (carboxyl, carbonyl and nitrogen content, degree of crystallinity and polymerization, surface area and swelling, and acidic properties) was investigated. Reactivity in the oxidation process was higher in mercerized cellulose than in native cellulose. The action of dilute solutions (10–15%) of N2O4 did not affect the degree of crystallinity of cellulose samples. Under these conditions, the oxidation took place mainly in amorphous regions and on the surface of crystallites. Oxidation in a concentrated (40%) N2O4 solution led to the destruction of crystallites, which increased the surface area and swelling of cellulose in water. The surface area and the swelling of OC samples increased with a decrease in the index of crystallinity. The acidic properties of OC were shown to increase with an increase of swelling in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4785–4791, 2004
Highly soluble conducting poly(ethylene oxide) grafted at two sites of poly(o‐aminobenzyl alcohol)
Authors: Hua Fengjun , Ruckenstein Eli
Published: August 2004

Poly(o‐aminobenzyl alcohol) (POABA) was grafted with poly(ethylene oxide)s (PEOs) through the reaction of tosylated PEO with both the hydroxide and amine moieties of reduced POABA. Reduced POABA was prepared through the acid‐mediated polymerization of o‐aminobenzyl alcohol, followed by neutralization with an aqueous ammonium hydroxide solution and reduction with hydrazine. The grafted copolymers were very soluble in common polar solvents, such as chloroform, tetrahydrofuran, and dimethylformamide, and the copolymers with longer PEO side chains (number‐average molecular weight > 164) were even water‐soluble. The conductivities of the doped grafted copolymers decreased with increasing PEO side‐chain length because of the nonconducting PEO and its torsional effect on the POABA backbone. The conductivity of highly water‐soluble POABA‐g‐PEO‐350 was 0.689 × 10−3 S/cm, that is, in the semiconducting range. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4756–4764, 2004
Fundamental kinetic aspects of living radical polymerization and the use of gel permeation chromatography to shed light on them
Authors: Fukuda Takeshi
Published: August 2004

The control achievable by living radical polymerization (LRP) is based on a kinetic balance of the activation–deactivation reversible reactions, which are specific to LRP, with conventional elementary reactions such as initiation, propagation, and termination. This work describes, as plainly as possible, how chains grow and how their polydispersity evolves as they experience activation–deactivation cycles and how these processes can be quantitatively analyzed by gel permeation chromatography. A comprehensive probability theory on the polydispersity indices of LRP polymers is presented. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4743–4755, 2004