bluuebunny/crossref_metadata_2025 huggingface dataset:
Poly(sulfobetaine)s and corresponding cationic polymers. X. Viscous properties of zwitterionic poly(sulfobetaine) derived from styrene–(N,N‐dimethylaminopropyl maleamidic acid) copolymer in aqueous salt solutions
Authors: Lee Wen‐Fu , Chen Yan‐Ming
Published: November 2003

A styrene–[N,N‐dimethyl (maleamidic acid) propyl ammonium propane sulfonate] (SDMMAAPS) copolymer was synthesized through an amidoacidation reaction of styrene–maleic anhydride (SMA) alternating copolymer with N,N‐dimethylaminopropylamine (ring‐opening reaction), which was then reacted with propane sultone. The effect of various salt solutions on the intrinsic viscosity of this ampholytic ADMMAAPS copolymer was investigated. The results showed that the effect of counter ions on the intrinsic viscosity of SDMMAAPS was not entirely similar to that of other zwitterionic poly(sulfobetaine)s. The greatest difference from other poly(sulfobetaine)s is the carboxylic group on the polymer chain unit of SDMMAAPS. The Huggins constants for SDMMAAPS in aqueous salt solutions, however, were also quite different from those of other sulfobetaine copolymers, such as styrene–N,N‐dimethyl (maleimido propyl) ammonium propane sulfonate] (SDMMAPS) copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 726–734, 2004
Compatibilization of high‐impact polystyrene/high‐density polyethylene blends by styrene/ethylene–butylene/styrene block copolymer
Authors: Chirawithayaboon Asira , Kiatkamjornwong Suda
Published: November 2003

Compatibilization of polymer blends of high‐impact polystyrene (HIPS) and high‐density polyethylene (HDPE) blend by styrene/ethylene–butylene/styrene (SEBS) was elucidated. Polymer blends containing many ratios of HIPS and HDPE with various concentrations of SEBS were prepared. The Izod impact strength and elongation at break of the blends increased with increases in SEBS content. They increased markedly when the HDPE content was higher than 50 wt %. Tensile strength of blends increased when the SEBS concentration was not higher than 5 pphr. Whenever the SEBS loading was higher than 5 pphr, the tensile strength decreased and a greater decrease was found in blends in which the HDPE concentration was more than 50 wt %. The log additivity rule model was applied to these blends, which showed that the blends containing the HIPS‐rich phase gave higher compatibility at the higher shear rates. Surprisingly, the blends containing the HDPE‐rich phase yielded greater compatibility at the lower shear rates. Morphology observations of the blends indicated better compatibility of the blends with increasing SEBS concentration. The relaxation time (T2) values from the pulsed NMR measurements revealed that both polymer blends became more compatible when the SEBS concentration was increased. When integrating all the investigations of compatibility compared with the mechanical properties, it is possible to conclude that SEBS promotes a certain level of compatibilization for several ratios of HIPS/HDPE blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 742–755, 2004
Processability and mechanical performance of hybrid composites based on poly(ether sulfone) modified with a glass fiber–reinforced liquid crystalline polymer
Authors: García M. , Eguiazábal J. I. , Nazábal J.
Published: November 2003

Hybrid composites, based on poly(ether sulfone) (PES) and glass fiber–reinforced copolyester liquid crystalline polymer (gLCP) up to 40% gLCP, were obtained by injection molding: these polymers were immiscible. Despite its higher viscosity, the gLCP acted as a processing aid for PES. The Young's modulus of the composites increased linearly with gLCP content, attributed to the opposing effects of increasing skin thickness and decreasing orientation of the fibrillated LCP in the skin. The break properties decreased with increasing gLCP content, mainly because of the lack of adhesion between the phases. The notched impact strength increased substantially on addition of 10% gLCP, suggesting that the dispersed rigid particles changed the fracture behavior of PES. The composite with 10% gLCP appeared to be the most attractive because it showed an increase in stiffness of 18%, 6.5‐fold impact strength, and a tensile strength similar to that of PES. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 854–860, 2004
Swelling and diffusion studies of poly(N‐isopropylacrylamide/itaconic acid) copolymeric hydrogels in water and aqueous solutions of drugs
Authors: Taşdelen Betül , Kayaman‐Apohan Nilhan , Güven Olgun , Baysal Bahattin M.
Published: November 2003

N‐Isopropylacrylamide/itaconic acid hydrogels (NIPAAm/IA) containing different amounts of itaconic acid prepared by irradiating with γ‐radiation were used in experiments on swelling and diffusion of the model drugs methylene blue, lidocaine, and sildenafil citrate (VIAGRA). The NIPAAm/IA hydrogels containing 0–3 mol % itaconic acid irradiated at 48 kGy has been used for swelling and diffusion studies in water and aqueous solutions containing the above‐mentioned model drugs. For these hydrogels, swelling studies indicated that swelling increased with the following order: water > lidocaine > methylene blue > VIAGRA. Diffusions of water and the drugs within hydrogels were found to be non‐Fickian in character. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 911–915, 2004
Free‐radical copolymerization and kinetic treatment of methyl methacrylate with N‐P‐tolylmaleimide
Authors: Yang Liting , Liu Yanhong , Li Yanfang , Gao Jungang , Zhang Liucheng , Jin Riguang
Published: November 2003

The free‐radical copolymerization of methyl methacrylate (MMA) with N‐P‐tolylmalemide (NPTMI) at 77°C in cyclohexanone solution initiated by AIBN was studied. The copolymer composition was calculated from the nitrogen content estimated by the Mico–Kijedldahl's method and by elemental analysis. The reactivity ratios have been calculated by Fineman and Ross method. The monomer reactivity ratios were rNPTMI = 1.24, rMMA = 2.1. The glass transition temperature (Tg) of the copolymers were determined by torsion braid analysis (TBA). The thermal stability was determined by thermogravimetric analysis (TGA). T50, temperature at which the weight loss reaches 50%, was abstained. The results showed that the Mn and Mw increased, whereas the NPTMI feed content increased. The Tg and T50 increased dramatically. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 867–870, 2004
Preparation of a porous conducting polymer film by electrochemical synthesis–solvent extraction method
Authors: Li Liang , Yan Feng , Xue Gi
Published: November 2003

Porous conducting polypyrrole (PPy) films have been obtained by electrochemical synthesis–solvent extraction method. The results of scanning electron microscopy (SEM) show that the size and the distribution of pores can be controlled during the electrochemical synthesis. The porous PPy films have sufficiently good mechanical properties, and electrochemical voltammetric studies imply that the porous films also have high electrical conductivity and good electrochemical reversibility. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 303–307, 2004
Influence of molecular weight of poly(ortho‐ethoxyaniline) on the corrosion inhibition efficiency of mild steel in acidic media
Authors: Daouadji M. Mekki , Chelali N.
Published: November 2003

The present work revealed that the chemical polymerization of ortho‐ethoxyaniline yields two types of polymers not only with different spectroscopic properties but also with different molecular weights: (1) a green form, which corresponds to the high molecular weight fraction of the polymer with a molecular weight of 800,000 g mol−1 based on the polystyrene calibration. It is mainly composed of quinoid and benzoid structures, which is an indication of a half‐oxidized polymer (emeraldine). This form of the polymer is insoluble in water‐miscible solvents like ethanol and methanol and thus cannot be tested in terms of corrosion inhibition efficiency; (2) a red form, which corresponds to the low molecular weight fraction of the polymer with a molecular weight of 44,000 g mol−1. It is composed mostly of quinoid structures and exhibits an oxidation state similar to that of the completely oxidized polymer (pernigraniline). In our case, the polymer fraction, which is soluble in alcohol, was first tested as a corrosion inhibitor for mild steel in acidic media, not only at conventional molecular weight (44,000 g mol−1) but also at different molecular weights. These different molecular weights of the polymer were obtained by adding varying amounts of neutral salt to the synthesis environment. Next, the effect of the molecular weight of the red form of the polymer on the corrosion inhibition efficiency of mild steel in hydrochloric acid solutions was investigated. The obtained results showed that the adsorption of the polymer alcoholic form obeys a Temkin adsorption isotherm with no significant change as function of inhibition efficiencies for a series of molecular weights ranging from13,000 to 124,000 g mol−1. The effect of temperature on the corrosion behavior of mild steel in 1M HCl with addition of 100 ppm of the alcoholic form of poly(ortho‐ethoxyaniline) was studied in the temperature range 25–60°C. The associated activation corrosion energy was determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1275–1284, 2004
Swelling behavior and determination of diffusion characteristics of acrylamide–acrylic acid hydrogels
Authors: Işık Belma
Published: November 2003

In this study, a random copolymer of acylamide and acrylic acid [poly(AAm‐co‐AA)] was prepared by a redox copolymerization method of their aqueous solutions. The effects of initial AAm/AA mole ratio, PEG 4000 content, and N,N′‐methylenebisacrylamide concentration on swelling behavior were investigated in water. Average molecular weights between crosslinks, percentage swelling, swelling equilibrium values, and diffusion/swelling characteristics (i.e., the structure of network constant, the type of diffusion, the initial swelling rate, swelling rate constant) were evaluated for every hydrogel systems. The hydrogels showed mass swelling capabilities in the range 789–1040% (for AAm/AA hydrogels), 769–930% (for AAm/AA hydrogels in the presence of PEG 4000), and 716–1040% (for AAm/AA hydrogels containing different concentrations of the crosslinker). The swelling capabilities of the hydrogels decreased with the increasing AA, PEG 4000, and crosslinker concentrations. The diffusion of water into AAm/AA hydrogels was found to be a non‐Fickian type. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1289–1293, 2004
Effect of water potential on sol–gel transition and intermolecular interaction of gelatin near the transition temperature
Authors: Miyawaki Osato , Norimatsu Yuko , Kumagai Hitoshi , Irimoto Yoshinobu , Kumagai Hitomi , Sakurai Hidetoshi
Published: November 2003

The sol–gel transition of gelatin, measured by thermal analysis and viscosity measurement, was analyzed in terms of the change in hydration state of polymer molecules. A new thermodynamic model was proposed in which the effect of water potential is explicitly taken into account for the evaluation of the free energy change in the sol–gel transition process. Because of the large number of water molecules involved and the small free energy change in the transition process, the contribution of water activity, aW, was proved to be not negligible in the sol–gel transition process in solutions containing such low‐molecular cosolutes as sugars, glycerol, urea, and formamide. The gel‐stabilization effect of sugars and glycerol was linear with aW, which seemed consistent with the contribution of water potential in the proposed model. The different stabilization effect among sugars and glycerol was explained by the difference in solvent ordering, which affects hydrophobic interaction among protein molecules. The gel‐destabilization effect of urea and formamide could be explained only by the direct binding of them to protein molecules through hydrogen bonding. On the contrary, the polymer–polymer interaction, measured by the viscosity analysis, in polyethyleneglycol and dextran solutions was not sensitive to the change in aW, suggesting that no substantial change in hydration state with aW occurred in these polymer solutions. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 482–491, 2003
Topological effects on the electrophoretic mobility of rigid rodlike DNA in polyacrylamide gels
Authors: Heuer Daniel M. , Saha Sourav , Archer Lynden A.
Published: November 2003

The electrophoretic migration of rigid rodlike DNA structures with well defined topologies has been investigated in polyacrylamide (PA) hydrogels prepared by copolymerization of acrylamide and N, N′‐methylenebisacrylamide. Previous studies have reported structural and dynamic characteristics of linear and branched DNA during electrophoresis in PA gels using a variety of experimental parameters. However, a thorough investigation aimed at establishing specific relationships between topological features of rigid rodlike DNA structures and their electrophoretic behavior is still needed. In order to study these topological effects on mobility, an intensive examination of the electrophoretic mobility of small linear and starlike DNA was performed. A series of model DNA structures with well‐defined branched topologies were synthesized with varying molecular parameters, such as number of arms surrounding the branch point and arm length. The electrophoretic mobility of these structures was then contrasted with a series of data obtained using linear DNA of comparable molecular size. When large DNA stars (M ≥ 60 bp) were compared with linear DNA of identical molecular weight, the Ferguson plots were quite different. However, small DNA stars (24–32 bp) and linear analogues had identical Ferguson plots. This indicates that a different motional mode or greater interaction with the gel exists for the larger DNA stars. When the total molecular weight of the DNA stars was held constant and the number of arms varied, the Ferguson plots for all the stars were identical. Additionally, a critical pore size was reached when the ratio of linear DNA mobility to star DNA mobility increased dramatically. Thus, while the incorporation of a single branch point can produce a large reduction in mobility, above a critical molecular size, the incorporation of additional branch points does not appear to provide further reduction in mobility. This finding is consistent with the transport properties of large synthetic star polymers, where a large reduction in their diffusion coefficient is observed when a single branch is added. When additional arms are incorporated, large synthetic stars do not display an appreciable further reduction in diffusion coefficient. The effect of arm length on mobility for rigid rod DNA stars was also studied. For four‐arm DNA stars, the mobility was found to scale as an exponential function of the arm length. Finally, a recently proposed phenomenological model was used to successfully fit the mobility data for linear rigid rod DNA at various concentrations of PA. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 471–481, 2003
Increasing age and APACHE II scores are the main determinants of outcome from pancreatic necrosectomy
Authors: Connor S , Ghaneh P , Raraty M , Rosso E , Hartley M N , Garvey C , Hughes M , McWilliams R , Evans J , Rowlands P , Sutton R , Neoptolemos J P
Published: November 2003

Background

The aim of this study was to identify factors associated with death after surgery in patients with extensive pancreatic necrosis.

Methods

Sixty-four patients who underwent pancreatic necrosectomy between 1996 and 2002 were studied.

Results

The median age was 60·5 (95 per cent confidence interval (c.i.) 57 to 64) years and 40 patients (62·5 per cent) were tertiary referrals. The initial median Acute Physiology And Chronic Health Evaluation (APACHE) II score was 9 (95 per cent c.i. 7·9 to 10·1) and there were 21 deaths (32·8 per cent). Twenty-eight patients (43·8 per cent) underwent minimally invasive retroperitoneal pancreatic necrosectomy (MIRP) and the remainder had open pancreatic necrosectomy (OPN); 44 (72·1 per cent) of 61 patients had infected pancreatic necrosis at the time of the first procedure. Seven patients who underwent MIRP died compared with 14 after OPN (P = 0·240). Patients who died were older than those who survived, with higher APACHE II scores at presentation, and before and after surgery (P = 0·001). Survivors had significantly longer times to surgery than those who died (P = 0·038). All 21 patients who died required intensive care compared with 26 of 43 survivors (P < 0·001). Thirty of 36 patients who had the OPN procedure required intensive care compared with only 17 of 28 patients who had MIRP (P = 0·042). Logistic regression analysis showed that only postoperative APACHE II score was an independent predictor of increased mortality (P = 0·031).

Conclusion

Advanced age and increasing APACHE II score, and a need for postoperative intensive care, were the most important predictors of outcome after pancreatic necrosectomy.
Risk factors predicting the development of complications after foreign body ingestion
Authors: Lai A T Y , Chow T L , Lee D T Y , Kwok S P Y
Published: November 2003

Background

The aim of this study was to determine the predictive risk factors for complications resulting from foreign body ingestion.

Methods

A consecutive series of 1338 patients with suspected foreign body ingestion presenting from 1996 to 2000 were studied retrospectively. The potential risk factors for complications after foreign body ingestion were analysed by multivariate logistic regression and included concurrent medical illness, age, duration and types of symptoms, types of foreign body ingested, positive cervical radiographic findings and the level of foreign body impaction.

Results

Fish bone (62·7 per cent) was the commonest type of foreign body ingested. Most of the objects were impacted at or above the cricopharyngeus, the commonest site being the valleculae (31·4 per cent). Multivariate analysis showed that presentation delayed for more than 2 days (P < 0·001), positive cervical radiographic findings (P < 0·001) and foreign body impacted at the cricopharyngeus (P = 0·009) or upper oesophagus (P = 0·005) were significant independent risk factors associated with the development of complications after foreign body ingestion.

Conclusion

In patients with a foreign body seen on plain cervical radiography, presentation delayed for more than 2 days after ingestion, and foreign body impacted at the level of the cricopharyngeus or oesophagus there is a high degree of correlation with the occurrence of complications. Awareness should be raised when these risk factors are present.
Prosthetic implants for hernia repair
Authors: Schumpelick V , Klinge U
Published: November 2003

The future of mesh
Human model of duodenogastro–oesophageal reflux in the development of Barrett's metaplasia (Br J Surg 2003; 90: 1120-1128)
Authors: Barham C P , Alderson D
Published: November 2003

The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses can be sent electronically via the BJS website (www.bjs.co.uk) or by post. All letters will be reviewed and, if approved, appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length. Letters submitted by post should be typed on A4-sized paper in double spacing and should be accompanied by a disk.
A comparative reappraisal of projections from the superficial laminae of the dorsal horn in the rat: The forebrain
Authors: Gauriau Caroline , Bernard Jean‐François
Published: November 2003

Projections to the forebrain from lamina I of spinal and trigeminal dorsal horn were labeled anterogradely with Phaseolus vulgaris‐leucoagglutinin (PHA‐L) and/or tetramethylrhodamine‐dextran (RHO‐D) injected microiontophoretically. Injections restricted to superficial laminae (I/II) of dorsal horn were used primarily. For comparison, injections were also made in deep cervical laminae. Spinal and trigeminal lamina I neurons project extensively to restricted portions of the ventral posterolateral and posteromedial (VPL/VPM), and the posterior group (Po) thalamic nuclei. Lamina I also projects to the triangular posterior (PoT) and the ventral posterior parvicellular (VPPC) thalamic nuclei but only very slightly to the extrathalamic forebrain. Furthermore, the lateral spinal (LS) nucleus, and to a lesser extent lamina I, project to the mediodorsal thalamic nucleus. In contrast to lamina I, deep spinal laminae project primarily to the central lateral thalamic nucleus (CL) and only weakly to the remaining thalamus, except for a medium projection to the PoT. Furthermore, the deep laminae project substantially to the globus pallidus and the substantia innominata and more weakly to the amygdala and the hypothalamus. Double‐labeling experiments reveal that spinal and trigeminal lamina I project densely to distinct and restricted portions of VPL/VPM, Po, and VPPC thalamic nuclei, whereas projections to the PoT appeared to be convergent. In conclusion, these experiments indicate very different patterns of projection for lamina I versus deep laminae (III–X). Lamina I projects strongly onto relay thalamic nuclei and thus would have a primary role in sensory discriminative aspects of pain. The deep laminae project densely to the CL and more diffusely to other forebrain targets, suggesting roles in motor and alertness components of pain. J. Comp. Neurol. 468:24–56, 2004. © 2003 Wiley‐Liss, Inc.
Differences in the expression of AMPA and NMDA receptors between axospinous perforated and nonperforated synapses are related to the configuration and size of postsynaptic densities
Authors: Ganeshina Olga , Berry Robert W. , Petralia Ronald S. , Nicholson Daniel A. , Geinisman Yuri
Published: November 2003

Axospinous synapses are traditionally divided according to postsynaptic density (PSD) configuration into a perforated subtype characterized by a complex‐shaped PSD and nonperforated subtype exhibiting a simple‐shaped, disc‐like PSD. It has been hypothesized that perforated synapses are especially important for synaptic plasticity because they have a higher efficacy of impulse transmission. The aim of the present study was to test this hypothesis. The number of postsynaptic AMPA receptors (AMPARs) is widely regarded as the major determinant of synaptic efficacy. Therefore, the expression of AMPARs was evaluated in the two synaptic subtypes and compared with that of NMDA receptors (NMDARs). Postembedding immunogold electron microscopy was used to quantify the immunoreactivity following single labeling of AMPARs or NMDARs in serial sections through the CA1 stratum radiatum of adult rats. The results showed that all perforated synapses examined were immunopositive for AMPARs. In contrast, only a proportion of nonperforated synapses (64% on average) contained immunogold particles for AMPARs. The number of immunogold particles for AMPARs was markedly and significantly higher in perforated synapses than in immunopositive nonperforated synapses. Although all synapses of both subtypes were NMDAR immunopositive perforated synapses contained significantly more immunogold particles for NMDARs than nonperforated ones. Multivariate analysis of variance revealed that the mode of AMPAR and NMDAR expression is related to the complexity of PSD configuration, not only to PSD size. These findings support the notion that perforated synapses may evoke larger postsynaptic responses relative to nonperforated synapses and, hence, contribute to an enhancement of synaptic transmission associated with some forms of synaptic plasticity. J. Comp. Neurol. 468:86–95, 2004. Published 2003 Wiley‐Liss, Inc.
Profile of the climate change in the Kingdom of Bahrain
Authors: Alnaser W. E. , Merzaa M. K.
Published: November 2003

Long‐term meteorological data from the Kingdom of Bahrain (1902 to 2001), along with other data from the Sultanate of Oman and the Kingdom of Saudi Arabia, were used to study the profile and the characteristics of the climate changes in the Kingdom of Bahrain. This article illustrates the possible effects of several factors, such as greenhouse gases (GHG), sunspot number, cosmic ray flux, planet conjunctions, the Earth's magnetic field, as well as volcanic eruption, on the profile of the climate change. In general, we found that the temperature variations, to a certain extent, are associated with the cyclic variations in sunspot number (the 11‐year cycle), which in turn affect the pattern of the cosmic ray flux due to the distortion of the interplanetary magnetic field. The latter is believed to influence cloud formation. In addition, the discrepancy in the climate change pattern in Bahrain was also attributed to the combined effect of the high local level of CO2 emissions as well as that of other cooling gases in the region. Copyright © 2003 John Wiley & Sons, Ltd.
Synergistic interaction between the EGFR tyrosine kinase inhibitor gefitinib (“Iressa”) and the DNA topoisomerase I inhibitor CPT‐11 (irinotecan) in human colorectal cancer cells
Authors: Koizumi Fumiaki , Kanzawa Fumihiko , Ueda Yutaka , Koh Yasuhiro , Tsukiyama Shoji , Taguchi Fumiko , Tamura Tomohide , Saijo Nagahiro , Nishio Kazuto
Published: November 2003

Epidermal growth factor receptor [EGFR (HER1, erbB1)] is a receptor with associated tyrosine kinase activity, and is expressed in colorectal cancers and many other solid tumors. We examined the effect of the selective EGFR tyrosine kinase inhibitor (EGFR‐TKI) gefitinib (“Iressa”) in combination with the DNA topoisomerase I inhibitor CPT‐11 (irinotecan) on human colorectal cancer cells. EGFR mRNA and protein expression were detected by RT‐PCR and immunoblotting in all 7 colorectal cancer cell lines studied. Gefitinib inhibited the cell growth of the cancer cell lines in vitro with an IC50 range of 1.2–160 μM by 3,(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) assay. Lovo cells exhibited the highest level of protein and autophosphorylation of EGFR and were the most sensitive to gefitinib. The combination of gefitinib and CPT‐11 induced supra‐additive inhibitory effects in COLO320DM, WiDR and Lovo cells, assessed by an in vitro MTT assay. Administration of gefitinib and CPT‐11 had a supra‐additive inhibitory effect on WiDR cells and tumor shrinkage was observed in Lovo cell xenografts established in nude mice, whereas no additive effect of combination therapy was observed in COLO320DM cells. To elucidate the mechanisms of synergistic effects, the effect of CPT‐11‐exposure on phosphorylation of EGFR was examined by immunoprecipitation. CPT‐11 increased phosphorylation of EGFR in Lovo and WiDR cells in time‐ and dose‐dependent manners. This EGFR activation was completely inhibited by 5 μM gefitinib and gefitinib‐induced apoptosis was enhanced by combination with CPT‐11, measured by PARP activation although no PARP activation was induced by 5 μM CPT‐11 alone. These results suggested that these modification of EGFR by CPT‐11, in Lovo cells, is a possible mechanism for the synergistic effect of CPT‐11 and gefitinib. These findings imply that the EGFR‐TKI gefitinib and CPT‐11 will be effective against colorectal tumor cells that express high levels of EGFR, and support clinical evaluation of gefitinib in combination with CPT‐11, in the treatment of colorectal cancers. © 2003 Wiley‐Liss, Inc.
Contribution of MEK/MAPK and PI3‐K signaling pathway to the malignant behavior of Ewing's sarcoma cells: Therapeutic prospects
Authors: Benini Stefania , Manara Maria Cristina , Cerisano Vanessa , Perdichizzi Stefania , Strammiello Rosaria , Serra Massimo , Picci Piero , Scotlandi Katia
Published: November 2003

Insulin‐like growth factor receptor I (IGF‐I)‐mediated circuit is a major autocrine loop for Ewing's sarcoma (ES) cells and appears to be particularly important in the pathogenesis of this tumor. In this study, we analyzed the contribution of the 2 major pathways of the intracellular IGF‐IR signaling cascade to the overall effects elicited by IGF‐I in ES. Both the mitogen‐activated protein kinase (MAPK) and phosphatidylinositol‐3‐kinase (PI3‐K) signaling pathways appeared to be constitutively activated in ES, likely due to the presence of the IGF‐IR‐mediated autocrine loop. We demonstrated that both MEK/MAPK (PD98059 or U0126) and PI3‐K inhibitors (LY294002) profoundly impaired ES cell growth in monolayer and soft agar basal conditions. Both PD98059 and LY294002 inhibited ES cell cycle progression by inducing G1 blockage, whereas only LY294002 significantly affected the survival of ES cells. Exogenous IGF‐I completely reverted LY294002‐induced growth inhibition by abrogating antiproliferative and proapoptotic effects of the PI3‐K inhibitor. By contrast, IGF‐I could not rescue cells from growth inhibition induced by PD98059. MEK/MAPK blockade also significantly reduced the migratory ability of ES cells, both in basal and IGF‐I‐induced conditions, and increased chemosensitivity to doxorubicin, a leader drug in the treatment of ES patients. Our findings therefore identify MAPK pathway as a promising target for pharmacologic intervention in ES. © 2003 Wiley‐Liss, Inc.
Prediction and classification of protein subcellular location—sequence‐order effect and pseudo amino acid composition
Authors: Chou Kuo‐Chen , Cai Yu‐Dong
Published: November 2003

Given a protein sequence, how to identify its subcellular location? With the rapid increase in newly found protein sequences entering into databanks, the problem has become more and more important because the function of a protein is closely correlated with its localization. To practically deal with the challenge, a dataset has been established that allows the identification performed among the following 14 subcellular locations: (1) cell wall, (2) centriole, (3) chloroplast, (4) cytoplasm, (5) cytoskeleton, (6) endoplasmic reticulum, (7) extracellular, (8) Golgi apparatus, (9) lysosome, (10) mitochondria, (11) nucleus, (12) peroxisome, (13) plasma membrane, and (14) vacuole. Compared with the datasets constructed by the previous investigators, the current one represents the largest in the scope of localizations covered, and hence many proteins which were totally out of picture in the previous treatments, can now be investigated. Meanwhile, to enhance the potential and flexibility in taking into account the sequence‐order effect, the series‐mode pseudo‐amino‐acid‐composition has been introduced as a representation for a protein. High success rates are obtained by the re‐substitution test, jackknife test, and independent dataset test, respectively. It is anticipated that the current automated method can be developed to a high throughput tool for practical usage in both basic research and pharmaceutical industry. © 2003 Wiley‐Liss, Inc.
Direct dynamic study on the hydrogen abstraction reaction CH3CN + OH → CH2CN + H2O
Authors: Li Qian‐Shu , Wang Chao Yang
Published: November 2003

The reaction of acetonitrile with hydroxyl has been studied using the direct ab initio dynamics methods. The geometries, vibrational frequencies of the stationary points, as well as the minimum energy paths were computed at the BHandHLYP and MP2 levels of theory with the 6‐311G(d, p) basis set. The energies were further refined at the PMP4/6‐311+G(2df, 2pd) and QCISD(T)/6‐311+G(2df, 2pd) levels of theory based on the structures optimized at BHandHLYP/6‐311G(d, p) and MP2/6‐311G(d, p) levels of theory. The Polyrate 8.2 program was employed to predict the thermal rate constants using the canonical variational transition state theory incorporating a small‐curvature tunneling correction. The computed rate constants are in good agreement with the available experimental data. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 251–257, 2004
Conformation‐dependent intermolecular interaction energies of the triphosphate anion with divalent metal cations. Application to the ATP‐binding site of a binuclear bacterial enzyme. A parallel quantum chemical and polarizable molecular mechanics investigation
Authors: Gresh Nohad , Shi Gen‐Bin
Published: November 2003

We have explored the conformation‐dependent interaction energy of the triphosphate moiety, a key constituent of ATP and GTP, with a closed‐shell divalent cation, Zn2+, used as a probe. This was done using the SIBFA polarizable molecular mechanics procedure. We have resorted to a previously developed approach in which triphosphate is built out from its elementary constitutive fragments, and the intramolecular, interfragment, interaction energies are computed simultaneously with their intermolecular interactions with the divalent cation. This approach has enabled reproduction of the values of the intermolecular interaction energies from ab initio quantum‐chemistry with relative errors <3%. It was extended to the complex of a nonhydrolyzable analog of ATP with the active site of a bacterial enzyme having two Mg2+ cations as cofactors. We obtained following energy‐minimization a very close overlap of the ATP analog over its position from X‐ray crystallography. For models of the ATP analog–enzyme complex encompassing up to 169 atoms, the values of the SIBFA interaction energies were found to match their DFT counterparts with relative errors of <2%. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 160–168, 2004
Computational study of conformational preferences of thioamide‐containing azaglycine peptides
Authors: Lee Ho‐Jin , Kim Jong Hyun , Jung Hee Jung , Kim Kun‐Young , Kim Eun‐Jung , Choi Young‐Sang , Yoon Chang‐Ju
Published: November 2003

The effect of thioamide substitution on the conformational stability of an azaglycine‐containing peptide, For‐AzaGly‐NH2 (1), was investigated for the sake of finding possible applications by using ab initio and DFT methods. As model compounds, For‐[ΨCSNH]‐AzaGly‐NH2 (2), For‐AzaGly‐[ΨCSNH]‐NH2 (3), and For‐[ΨCSNH]‐AzaGly‐[ΨCSNH]‐NH2 (4) were used. Two‐dimensional ϕ‐ψ potential energy surfaces (PESs) for 2–4 were calculated at the B3LYP/6‐31G*//HF/6‐31G* level in gas (ε = 1.0) and in water (ε = 78.4) by applying the isodensity polarizable continuum model (IPCM) method. On the basis of these PESs, the minimum energy conformations for 2–4 were characterized at the B3LYP level with 6‐31G*, 6‐311G**, and 6‐31+G** basis sets. The remarkable structural effect of thioamide substitution for 2–4 is that β‐strand structure is observed as a global or local minimum. The minima of 2–4 are also compared with those for glycine and thioamide‐containing glycine peptides. Our theoretical results demonstrate that compounds 2–4 would be used to design controllable secondary structures. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 169–178, 2004
Detection of low copy numbers of HIV‐1 proviral DNA in patient PBMCs by a high‐input, sequence‐capture PCR (Mega‐PCR)
Authors: Böni Jürg , Shah Cyril , Flepp Markus , Lüthy Ruedi , Schüpbach Jörg
Published: November 2003

An internally controlled high‐input PCR method, termed HIV‐1 Mega‐PCR was developed to lower the detection limit of HIV‐1 DNA polymerase chain reaction (PCR) and to improve its value as a complementary diagnostic test. It is based on PCR amplification of two target sequences in the gag gene of HIV‐1 following the selective capture of the targeted sequence and removal of unselected DNA from up to 500 μg of DNA. Efficient selection and amplification was monitored by inclusion of two mimic plasmids. The method was evaluated with buffy coat cells from healthy blood donors which were spiked with blood from 106 different HIV‐1‐infected individuals, and with 107 HIV‐1 seronegative control buffy coats. All specimens from HIV‐infected individuals were positive by a PCR protocol using 1 μg of patient DNA. Amplification of 1 μg DNA of the 106 spiked, diluted samples resulted in 68 double positive, 14 single positive, and 24 double negative reactions. In the Mega‐PCR, the average input was 260 ± 84 μg DNA containing an estimated 1.1 ± 0.6% of spiked patient DNA. Of the 106 samples tested by Mega‐PCR, 102 were positive and three negative. One failed to select the mimic plasmid. Among the 107 negative buffy coat controls, none was false‐positive and four exhibited a failure of the internal reaction control. Application of HIV‐1 Mega‐PCR to clinical specimens from seroreverting newborns of HIV‐infected mothers and seroindeterminate, PCR‐negative specimens revealed no indication for HIV infection, whereas three samples from confirmed, HIV‐1‐infected but PCR negative individuals showed evidence of the presence of HIV‐1 DNA. Mega‐PCR lowers the detection limit of an individual analysis to approximately 0.01 HIV‐1 DNA copies/μg of applied DNA and may help to confirm or exclude HIV‐1‐infection in difficult situations diagnostic. J. Med. Virol. 72:1–9, 2004. © 2004 Wiley‐Liss, Inc.
Genetic variability of human rotavirus strains isolated from Eastern and Northern India
Authors: Das Soma , Varghese Vici , Chaudhuri Susmita , Barman Provaboti , Kojima Kazunobu , Dutta Phalguni , Bhattacharya Sujit K. , Krishnan Triveni , Kobayashi Nobumichi , Naik Trailokya N.
Published: November 2003

An epidemiological study was conducted in Eastern and Northern India to determine the genomic diversity of rotaviruses in these parts of the country. In 2001, a total of 126 Group A rotavirus positive samples were detected from children below 4 years of age with diarrhoea from Kolkata, Dibrugarh and Bhubaneswar in Eastern India, and Chandigarh, a city in Northern India. All the samples were genotyped for VP7 (G‐type) and VP4 (P‐type) gene by reverse transcription (RT) and multiplex PCR using different type specific primers. The strains with G1P[8] (32.5%) was predominant as reported earlier [Das et al. (2002) J Clin Microbiol 40:146–149] followed by G2P[4](4.7%) and only one sample was of G4P[8] specificity. Along with these common types some rare strains like G1P[6], G2P[8], G2P[6], G4P[4], and G4P[6] were also detected in 14.3% of cases. Thirty percent of samples in this study were mixed infections and 21 (16.7%) specimens remained untypeable either for the VP7 or for the VP4 gene. After sequencing of the VP7 gene, two G9 strains (RMC321 and ISO‐3) were identified with P[8] and P[19] specificities. Sequence analysis revealed that they have much lower homology to the G9 strains (116E, INL1, and G16) isolated earlier from Indian subcontinent, but have much higher homology to isolates from Argentina, Brazil, Malawi, Taiwan, and USA suggesting a separate progenitor for these strains. J. Med. Virol. 72:156–161, 2004. © 2004 Wiley‐Liss, Inc.
Hepatitis B viremia is associated with increased risk of hepatocellular carcinoma in chronic carriers
Authors: Tang Baiqing , Kruger Warren D. , Chen Gang , Shen Fumin , Lin Wen Yao , Mboup Souleymane , London W. Thomas , Evans Alison A.
Published: November 2003

The role of quantitative viral load in development of hepatocellular carcinoma (HCC) among chronic hepatitis B virus (HBV) carriers was evaluated using real‐time PCR (TaqMan PCR), a highly sensitive method for quantitative detection of HBV DNA. Serum samples collected at study entry from HCC cases and matched controls were chosen separately from ongoing prospective cohort studies in Senegal, West Africa, and Haimen City, China. For 14 HCC cases and 28 controls from Senegal, the relative risk (RR, 95% CI) of HCC was 15.6 (2.0–124.3) for those positive by the TaqMan PCR assay. Average length of follow‐up (study entry to death from HCC) among cases was 2.8 (±1.6) years. The paired median difference between cases and controls was 3.8 × 104 virions/ml, with cases higher (P = 0.09). In order to clarify the relationship with lower‐titer viremia, we selected 55 cases and 55 matched controls from the Chinese cohort all negative for serum HBV DNA by conventional dot blot hybridization. In this group, the RR associated with HBV DNA positivity by TaqMan PCR was 3.1 (1.1–9.2), with an average duration of follow‐up of 3.3 (±2.1) years. The median difference in quantitative viremia between cases and controls was 6.0×104 virions/ml, with cases higher (P < 0.0001). Increased risk appeared to be confined to subjects with viral loads >2.3 × 104 virions/ml. In conclusion, HBV viremia, except perhaps at extremely low levels, is associated with increased risk for HCC in prospective studies of chronic carriers in two disparate populations. J. Med. Virol. 72:35–40, 2004. © 2004 Wiley‐Liss, Inc.
Suppression of generation and replication of acyclovir‐resistant herpes simplex virus by a sensitive virus
Authors: Okuda Tomoko , Kurokawa Masahiko , Matsuo Koma , Honda Mariko , Niimura Michihito , Shiraki Kimiyasu
Published: November 2003

The role of acyclovir‐sensitive herpes simplex virus (HSV) was analyzed in the process of its replacement by a resistant virus in vitro and in vivo in the aspect of acyclovir therapy. The mode of replacement of acyclovir‐sensitive HSV with acyclovir‐resistant HSV was examined by the passages of acyclovir‐sensitive wild type HSV in Vero cells under acyclovir‐treatment. The development of resistance was monitored more adequately by counting the number of acyclovir‐resistant viruses in 10,000 plaque forming units than by the conventional susceptibility assay. The resistance increased with the proportion of thymidine kinase‐deficient (TK−) viruses, when the susceptibilities of acyclovir‐treated HSV population to 5′‐iodo‐2′deoxyuridine and phosphonoacetic acid were examined. The increased resistance was due to the increased proportion of acyclovir‐resistant virus but not intermediately resistant virus. Infection with mixtures of TK− and acyclovir‐sensitive strains rendered TK− sensitive to acyclovir, and virus yields were reduced to the levels of acyclovir‐sensitive virus in Vero cells. Their yield reduction depended on the proportion of acyclovir‐sensitive viruses and induction of TK activity. This reduction in virus yields of the mixture of TK− and acyclovir‐sensitive strains was confirmed by acyclovir treatment in the skin of mice with cutaneous infection. Acyclovir treatment combined with superinfection of acyclovir‐sensitive virus delayed the development of herpetic skin lesions due to acyclovir‐resistant virus and reduced virus yields in the infected skin. Acyclovir‐sensitive virus plays an important role in suppressing the generation and replication of acyclovir‐resistant virus during acyclovir therapy. J. Med. Virol. 72:112–120, 2004. © 2004 Wiley‐Liss, Inc.
An antisense construct reduces N‐methyl‐D‐aspartate receptor 2A expression and receptor‐mediated excitotoxicity as determined by a novel flow cytometric approach
Authors: Mattar Pierre A. , Holmes Kevin D. , Dekaban Gregory A.
Published: November 2003

The N‐methyl‐D‐aspartate receptor (NMDAR) is a major neurotransmitter receptor in the central nervous system (CNS), with functional roles in learning, memory, and sensation. Several mechanisms potentiate NMDARs, and NMDAR hyperexcitability plays pathophysiological roles in many conditions, such as neurodegenerative disease, ischemia, and chronic conditions arising from spinal cord injury. Previous research suggests that the NR2A subunit of the receptor contributes to NMDAR excitotoxicity in heterologous cells and in neurons in vivo. To investigate the role of NR2A in NMDAR excitotoxicity, we have developed a system based on flow cytometry that allows rapid evaluation of the effect of antisense constructs on protein expression and channel function. The enhanced yellow fluorescent protein (EYFP) was fused to obligatory NMDAR subunits, allowing expression to be monitored in living cultured cells. An NR2A antisense construct, asNR2A, specifically and effectively reduced NR2A‐EYFP expression. NR1 and NR2A fusion proteins formed functional, excitotoxic channels upon co‐expression. The asNR2A RNA significantly reduced NMDAR excitotoxicity when NR2A levels were limiting for channel formation. Using our assay system, further optimization can be achieved rapidly. The asNR2A construct and the assays developed for this study can be used to provide insights into NMDAR biology and disease. © 2003 Wiley‐Liss, Inc.
On the structure of sulfonic acid doped thermoreversible polyaniline gels
Authors: Jana Tushar , Chatterjee Jhunu , Nandi Arun K.
Published: November 2003

Thermoreversible polyaniline (PANI) gels of varying weight fraction of PANI are prepared with dinonylnaphthalenesulfonic acid (DNNSA), dinonylnapthalenedisulfonic acid (DNNDSA), (±)‐camphor‐10‐sulfonic acid (CSA) and n‐dodecyloxo sulfonic acid (DOSA). The surface morphology is studied using atomic force microscopy (AFM) for 15% PANI concentration (w/w). The AFM study clearly reveals the formation of lamellar morphology in the gel. X‐ray scattering experiments of these gels also put evidence for the lamellar structure formation. The lamellar thickness measured from X‐ray results remain invariant with composition for PANI‐DNNSA and PANI‐DNNDSA systems but for PANI‐CSA and PANI‐DOSA lamellar thickness varies with PANI concentration. Both X‐ray diffraction and electron diffraction experiments on the gels of different compositions reveal the existence of new spacings of lower dhkl values which are invariant with composition. These results characterize the formation of new unit cells in the lamella due to the microcrystallization of elongated surfactant tails formed under the doped condition. The dhkl values characterizing the lamellar thickness, bilayer thickness and monolayer thickness are discussed from the molecular models using the MMX program. The variation of lamellar thickness with PANI concentration is discussed from the cohesive force of the surfactant tails within the lamella.
Conformational characteristics of stereoregular PMMA and of the stereocomplex: new insights from FTIR measurements
Authors: Tretinnikov Oleg N.
Published: November 2003

Isotactic (i) and syndiotactic (s) PMMA polymers differ markedly in the physical properties. The fact that these physically unlike macromolecules strongly attract each other with the resultant formation of stereocomplexes is indeed remarkable. Although stereoregular PMMAs and the stereocomplex have been studied over decades, their conformational characteristics are yet a matter of controversy. We performed variable‐temperature FTIR measurements on i‐PMMA and s‐PMMA, followed by a detailed analysis of the temperature dependence of integrated band intensities for C‐O stretching modes in the region 1050‐1300 cm−1 and achieved, for the first time, the unambiguous conformational assignment for the C‐O bands. This enabled reliable IR spectroscopic determination of conformational energies for the backbone and for the ester group. Besides, a comparative analysis of the C‐O band intensities in the FTIR spectra of single‐component and stereocomplex PMMA films, based on the established band assignments, revealed new features in the structure of the stereocomplex.
Starch‐modified filters used for the removal of dyes from waste water
Authors: Delval Franck , Crini Grégorio , Vebrel Joël , Knorr Michael , Sauvin Gilles , Conte Emmanuel
Published: November 2003

The present article proposes the use of starch‐enriched flour as low‐cost adsorbent of dyes. The adsorbents have been prepared by reticulation of starch‐enriched flour using epichlorohydrin as crosslinking agent. These starch‐modified filters exhibit interesting properties in terms of sorption rate. Studies concerning the sorption capacity are presented. The influence of the amine groups and the chemical structure of dyes are also studied. The regeneration procedure of the filters is showed and discussed. In order to explain the results, an adsorption mechanism mainly based on physical adsorption and interactions such as hydrogen bonds and ion‐exchange due to the nature of the polymer network is proposed.