bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photopolymerization and shrinkage kinetics of in situ crosslinkable N‐vinyl‐pyrrolidone/poly(ε‐caprolactone fumarate) networks
Authors: Sharifi Shahriar , Mirzadeh Hamid , Imani Mohammad , Atai Mohammad , Ziaee Farshid 
Published: July 2007

AbstractBiodegradable, injectable and in situ photocrosslinkable macromers based on fumaric acid and polycaprolactone (PCLF) were prepared and characterized by FTIR, 1HNMR, and 13CNMR spectroscopy. The multifunctional macromers dissolved in N‐vinyl pyrollidone (NVP) were photopolymerized by visible light irradiation in the presence of camphorquinone as photoinitiator. The photocrosslinking reaction was monitored by measuring shrinkage strain and shrinkage strain rate. The degree of photopolymerization reaction i.e. degree of conversion (DC%) was traced using FTIR spectroscopy. A three level factorial design was developed to study the effects of initiator concentration, NVP concentration, and molecular weight of PCLF upon photocrosslinking characteristics including degree of conversion and shrinkage strain. Results revealed that although neat PCLF was photopolymerized, but it was putty like after 220 seconds of irradiation and showed a very low degree of conversion (29%). Adding about 20% NVP caused a dramatic increase in its degree of conversion (63.33%). Increasing NVP up to 50% resulted in a decrease in DC% because of lower reactivity of NVP and leaving more unreacted NVP monomers. Sol fraction studies supported these results indicating that at higher NVP concentration, most of NVP and PCLF have not undergone the crosslinking reaction, leading to 55% decrease in DC%. Shrinkage strain measurement also confirmed the FTIR results. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Potential use of cholecalciferol polyethylene glycol succinate as a novel pharmaceutical additive
Authors: Zhao H. Z. , Tan E. C. , Yung L. Y. L. 
Published: July 2007

AbstractD‐α‐tocopheryl polyethylene glycol succinate (TPGS) has been utilized in numerous drug delivery formulations in recent years. Because of its amphiphilic structure, it can be used as emulsifier and vehicle for lipid‐based drug delivery formulations. It is also an effective P‐glycoprotein (P‐gp) inhibitor. However, TPGS represents only one of the surfactants in the class of “Vitamin‐PEG” conjugated surfactants. To design a new adjuvant or additive, a conjugate made of vitamin D (cholecalciferol) and PEG‐cholecalciferol polyethylene glycol succinate (CPGS) was synthesized via a two‐step reaction. We hypothesized that CPGS may exhibit similar characteristics to TPGS, and thus the physicochemical properties as well as the anticancer properties of CPGS were studied. The results demonstrated that CPGS reduced the particle size and increased the encapsulation efficiency of the PLGA nanoparticles, indicating that CPGS may also have the emulsifier function similar to TPGS. The drug release profiles showed that the nanoparticles with CPGS additive had a lower initial burst and more sustained release pattern. In vitro testing with Caco‐2 cells showed that CPGS could increase the cytotoxicity of DOX‐loaded PLGA nanoparticles. Based on the rhodamine accumulation study, the increased cytotoxicity is possibly due to the P‐gp inhibition by CPGS. From current results, the use of CPGS as an adjuvant is promising and may enhance the efficacy of the overall drug delivery system. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
The response of fibroblasts to hexagonal nanotopography fabricated by electron beam lithography
Authors: Dalby Matthew J. , Gadegaard Nikolaj , Wilkinson Chris D.W. 
Published: July 2007

AbstractIt has been known for many years that cells will react to the shape of their microenvironment. It is more recently becoming clear that cells can alter their morphology, adhesions, and cytoskeleton in response to their nanoenvironment. A few studies have gone further and measured cellular response to high‐adhesion nanomaterials. There have, however, been practical difficulties associated with genomic studies focusing on low‐adhesion nanotopographies. Because of advancement in fabrication techniques allowing the production of large area of structure and the ability to amplify mRNA prior to microarray hybridization, these difficulties can be overcome. Here, electron beam lithography has been used to fabricate arrays of pits with 120 nm diameters, 100 nm depth and 300 nm center to center spacing in hexagonal arrangement. Electron and fluorescent microscopies have been used to observe morphological changes in fibroblasts cultured on the pits. 1.7k gene microarray was used to gauge genomic response to the pits. The results show reduction in cellular adhesion, decrease in spreading, and a broad genomic down‐regulation. Also noted was an increase in endocytotic activity in cells on the pits. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
In situ apatite forming injectable hydrogel
Authors: Ho Emily , Lowman Anthony , Marcolongo Michele 
Published: July 2007

AbstractInjectable polymers are attractive materials for tissue augmentation or replacement. Thermosensitive hydrogels, especially poly(N‐isopropylacryamide), have been investigated for these applications to exploit the lower critical solution temperature (LCST) which falls between room and body temperatures. Some practical limitations to the material are the load‐bearing capabilities and the ability to bond to the host tissue. In this work, we evaluated a novel, injectable apatite‐forming material system: poly(N‐isopropylacryamide)‐co‐poly(ethyleneglycol) dimethacrylate, with the addition of tri‐methacryloxypropyltrimethoxysilane (MPS). We have previously reported that MPS concentration permits the material system to be tuned to different compressive moduli ranging from 50–700 kPa without altering the LCST of the material. Here, we explore the apatite formation of this material system in protein‐free and protein‐containing SBF. The MPS‐containing hydrogel system exhibited apatite formation throughout the gel thickness. The apatite formation was inhibited by the presence of proteins. This mechanism is likely controlled by the silanol groups (Si‐OH) in MPS, which provided attachment sites for calcium and initiated mineral dissolution from the simulated biological environments. The challenge of this material system is to balance the network‐forming and modulus‐enhancing MPS while maintaining an injectable hydrogel for potential tissue regeneration. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Ginkgolides protect PC12 cells against hypoxia‐induced injury by p42/p44 MAPK pathway‐dependent upregulation of HIF‐1α expression and HIF‐1DNA‐binding activity
Authors: Li Zhu , Ya Ke , Xiao‐Mei Wu , Lei Yang , Yang Lu , Ming Qian Zhong 
Published: July 2007

AbstractWe hypothesized that the neuroprotective role of the standardized Ginkgo biloba (Ginkgoaceae) extract EGb 761 under hypoxic conditions might be associated with its function to increase HIF‐1 activity based on the fact that oxygen availability is crucial for cellular metabolism and viability and that HIF‐1 plays an essential role in cellular oxygen homeostasis under hypoxic conditions. In this study, we therefore investigated the effects of ginkgolides, the main constituent of the non‐flavone fraction of EGb 761, on the content and activity of HIF‐1α, a key factor to determine HIF‐1 activity, in hypoxic PC12 cells induced by cobalt chloride. Our data demonstrated that ginkgolides have a significant protective role against hypoxia‐induced injury in the PC12 cells. The findings also strongly support our hypothesis that the protective role of ginkgolides is due to the up‐regulation of HIF‐1α protein expression and modification through the ginkgolides‐induced activation of the p42/p44 MAPK pathway. In addition, it was evident that ginkgolides could significantly increase the HIF‐1 DNA binding activity, which might also be associated with the protective effects of ginkgolides by promoting the expression of target genes of HIF‐1 under hypoxic conditions. J. Cell. Biochem. 103: 564–575, 2008. © 2007 Wiley‐Liss, Inc.
Proteasomal inhibition and apoptosis regulatory changes in human isolated lymphocytes: The synergistic role of dopamine
Authors: Bazzini Eleonora , Samuele Alberta , Granelli Marcella , Levandis Giovanna , Armentero Marie‐Therese , Nappi Giuseppe , Blandini Fabio 
Published: July 2007

AbstractAbnormal deposition of protein aggregates and increased susceptibility to apoptotic cell death may result from defects in the activity of the ubiquitin‐proteasome system (UPS); neurotoxicity related to UPS defects seems to require dopamine to be fully expressed. The aim of this study was to investigate the pro‐apoptotic effects caused by proteasomal activity inhibition, as well as the synergistic effect of dopaminergic stimulation in human lymphocytes isolated from healthy volunteers. Cells were incubated 20 h at 37°C, with: (1) lactacystin, (2) increasing concentrations of dopamine or (3) mixture of dopamine and lactacystin. Activities of proteasome 20S and pro‐apoptotic caspases‐3 and ‐9 and levels of anti‐apoptotic Bcl‐2 were measured with fluorimetric or immunochemical assays, while a “DNA diffusion” assay was used to determine the apoptosis. Incubation of lymphocytes with lactacystin, which caused reduction of proteasomal activity, was associated with activation of caspases. A clear, dose‐dependent reduction of proteasomal activity was also seen in the presence of increasing doses of dopamine, which was accompanied by a slight dose‐dependent increase of caspases activities and Bcl‐2 levels. Both effects on proteasome and caspase activities were enhanced when cells were simultaneously exposed to lactacystin and elevated concentrations of dopamine. Apoptosis was detected in all treated samples, but not in controls, without significant differences among the treatment groups; however, the association of dopamine and lactacystin induced a clear reduction in the number of cells being analyzed, pointing to marked cytotoxicity. Our data confirm the potentiation of cytotoxicity related to proteasome inhibition, in the presence of dopaminergic stimulation. J. Cell. Biochem. 103: 877–885, 2008. © 2007 Wiley‐Liss, Inc.
Melanoma cancer vaccines and anti‐tumor T cell responses
Authors: Vujanovic Lazar , Butterfield Lisa H. 
Published: July 2007

AbstractMelanoma is a disease which has been shown to be responsive to immune intervention. This has been suggested by reports of spontaneous responses of metastatic disease with strong immune infiltrates, and supported by recent data correlating clinical response after IFNα treatment with development of generalized autoimmunity. Since the identification of melanoma‐associated tumor antigens, many groups have performed clinical trials to take advantage of this discovery with melanoma‐specific cancer vaccines. These trials, in which multiple antigen delivery strategies have been tested in hundreds of patients, have demonstrated that these vaccines are safe, immunogenic, and yield a low frequency of objective clinical responses. The ability to perform careful immunological monitoring has allowed important insights into the nature of the anti‐tumor immunity generated by these vaccinations. While many trials have found that the absolute frequency of T cells specific for a vaccine‐encoded antigen are a marker of immunization, it does not correlate with objective clinical response. Induction of broad immunity to multiple tumor antigens, taking advantage of cross‐reactive T cells and activation of persistent T cells may be more important. Harnessing additional modes of amplifying immune responses (lymphodepletion, cytokine support, inhibition of negative immune self‐regulation) are now being tested and should improve clinical responses from 5% to 10% complete response seen currently. J. Cell. Biochem. 102: 301–310, 2007. © 2007 Wiley‐Liss, Inc.
Effects of a phosphinothricin based herbicide on selected groups of soil microorganisms
Authors: Pampulha M. E. , Ferreira M. A. S. S. , Oliveira A. 
Published: July 2007

AbstractThe effects of the herbicide glufosinate‐ammonium on soil microbial populations and activity were observed in a laboratory microcosms over a 40 day period. Culturable aerobic bacteria, fungi and actinomycetes, the fundamental groups of heterotrophic microorganisms, were studied. Nitrifiers, considered a very sensitive group to these compounds were also evaluated. Since herbicides have been found to inhibit decomposition of cellulose in the soil, the effects of glufosinate on cellulolytic bacteria and fungi were determined. Dehydrogenase activity as a measure of microbial activity was another parameter considered. Both stimulating and inhibitory effects on microbial populations were observed, depending on concentration of the herbicide and the period of incubation. A severe inhibiting effect of glufosinate on dehydrogenase activity was found. We concluded that the widespread use of this herbicide may have possible injurious effects on soil microorganisms and their activities. The toxicity exerted by glufosinate may lead to a shift in microbial community structure tending toward a significant loss in functional diversity. Dehydrogenase activity was shown to be an important indicator of glufosinate side‐effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microbial competition, lack in macronutrients, and acidity as main obstacles to the transfer of basidiomycetous ground fungi into (organically or heavy‐metal contaminated) soils
Authors: Gramss Gerhard , Bergmann Hans 
Published: July 2007

AbstractNon‐symbiotic soil microorganisms which have been expensively engineered or selected to support plant nutrition, control root diseases, degrade xenobiotic hydrocarbons, and repress or stimulate heavy metal uptake of plants fail to survive in target soils. This prompted studies into the role of chemistry and microbial pre‐colonization of 23 top soils in long‐term growth of basidiomycetes. Fungi are seen as auxiliary agents in soil remediation. Untreated soils (1.5 L) were colonized by lignocellulose preferring ground fungi such as Agaricus aestivalis, A. bisporus, A. campestris, A. edulis, A. macrocarpus, A. porphyrizon, Agrocybe dura, A. praecox, Clitocybe sp., Coprinus comatus, Lepista nuda, L. sordida, Macrolepiota excoriata, M. procera, Stropharia coronilla, and S. rugoso‐annulata. Spawn mycelia of fairy‐ring‐type fungi such as Agaricus arvensis, A. fissuratus, A. langei, A. lanipes, A. pilatianus, Lyophyllum sp., and Marasmius oreades died back in contact with non‐sterile soils. Fungal growth correlated positively with the soils' Ct Ca K Mg content and negatively with microbial CO2 evolution. Pasteurization and autoclaving increased mycelial growth and life span in soils pH 6.6–8.2. Growth of pH‐sensitive but not of pH–tolerant fungi was inhibited on the Ca‐deficient soils pH 4–4.4 (–5.6) and was not improved by autoclaving. The pretended fungistasis of acid soils to pH‐sensitive fungi was controlled by N P K mineral (pH not altering) or organic (pH increasing) fertilizing as well as by neutralization with NaOH or CaCO3. Although microbial competition was mortal to 33% of the fungal mycelia inserted into natural unplanted soils, further seriously antifungal effects beyond those pretended by low pH conditions and shortage in mineral macronutrients were not identified. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Responses in the mycelial growth of Aspergillus niger isolates to arsenic contaminated environments and their resistance to exogenic metal stress
Authors: Bučková Mária , Godočíková Jana , Polek Bystrík 
Published: July 2007

AbstractIsolates of Aspergillus niger, selected from coal dust sediment of a mine containing As (400 mg/kg), pH 3.3–2.8, and from river sediment found near the mine (As, 363 mg/kg, Sb, 93 mg/kg), pH 5.2–4.8, growing on Czapek‐Dox agar exhibited distinct responses in the mycelial growth in arsenic contaminated environments. The radial growth of the isolate from the coal dust in comparison to the control strain from an environment without pollution was reduced approximately to one‐half. It formed black, very small compact colonies, with dense sporulation. The opposite, the strain from the river sediment, grew better in Czapek‐Dox agar like the control. It formed larger colonies with dense centre and strong sporulation. Also, the culture from river sediment developed faster than the coal dust isolate and control strain. Differences were also recorded in size and thickness of conidia heads, phialide, metulae, and conidiophores. Both isolates from contaminated localities exhibited higher tolerance to exogenic toxic effects of As5+, Cd2+ and Cu2+ (5, 25 or 50 mg/l) than the control culture. Tolerance was monitored using the growth of biomass in liquid Czapek‐Dox medium. We confirmed the morphological identification of our isolates to A. niger species with the PCR method. The results refer to complicated relations between biotic and abiotic effects that may directly affect the processes observed in the in situ environment. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antifungal activity of salaceyin A against Colletotrichum orbiculare and Phytophthora capsici
Authors: Park C. N. , Lee D. , Kim W. , Hong Y. , Ahn J. S. , Kim B. S. 
Published: July 2007

AbstractThe antifungal activities of novel salicylic acid derivatives, salaceyin A, 6‐(9‐methyldecyl) salicylic acid, and salaceyin B, 6‐(9‐methylundecyl) salicylic acid were evaluated against plant pathogenic fungi. Salaceyin A showed antifungal activity against Cladosporium cucumerinum, Colletotrichum orbiculare and Phytophthora capsici at 64 μg ml–1 while salaceyin B was less effective. In vitro antifungal activities of the compounds were influenced by the experimental pH value of the MIC test medium wherein their antifungal activities were enhanced by increasingly acidic conditions. Salaceyin A showed potent in vivo control efficacy against Phytophthora blight in pepper plants. The disease was effectively suppressed at 500 μg ml–1, which was comparable to the commercial fungicide, metalaxyl. Salaceyin A suppressed anthracnose development on cucumber leaves in a concentration dependent manner. The control efficacy of salaceyin A against C. orbiculare infection was similar to chlorothalonil when applied prior to pathogen inoculation. Since the salaceyins are derivatives of salicylic acid, a known important signal molecule critical to plant defenses against pathogen invasion, we investigated the possibility that exogenous application of the salaceyin A would activate a systemic acquired resistance against P. capsici infection and C. orbiculare development on pepper and cucumber plants respectively. The addition of 500 μg ml–1 of salaceyin A to the plant root systems did not significantly decrease disease development in the hosts. We are led to conclude that the disease control efficacy of salaceyin A against the Phytophthora blight and anthracnose diseases, mainly originates from the direct interaction of the agent with the pathogens. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical and experimental studies of the diketene system: Product branching decomposition rate constants and energetics of isomers
Authors: Bui Binh , Tsay Ti Jo , Lin M. C. , Melius C. F. 
Published: July 2007

AbstractThe kinetics and mechanism for the thermal decomposition of diketene have been studied in the temperature range 510–603 K using highly diluted mixtures with Ar as a diluent. The concentrations of diketene, ketene, and CO2 were measured by FTIR spectrometry using calibrated standard mixtures. Two reaction channels were identified. The rate constants for the formation of ketene (k1) and CO2 (k2) have been determined and compared with the values predicted by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory for the branching reaction. The first‐order rate constants, k1 (s−1) = 1015.74 ± 0.72 exp(−49.29 (kcal mol−1) (±1.84)/RT) and k2 (s−1) = 1014.65 ± 0.87 exp(−49.01 (kcal mol−1) (±2.22)/RT); the bulk of experimental data agree well with predicted results. The heats of formation of ketene, diketene, cyclobuta‐1,3‐dione, and cyclobuta‐1,2‐dione at 298 K computed from the G2M scheme are −11.1, −45.3, −43.6, and −40.3 kcal mol−1, respectively. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 580–590, 2007
Micellar and salt effects on the interaction of [Cu(II)‐Gly‐Gly]+ with ninhydrin
Authors: Akram Mohd. , Zaidi Neelam Hazoor , Kabir‐ud‐Din  
Published: July 2007

AbstractThe effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the kinetics of interaction of copper dipeptide complex [Cu(II)‐Gly‐Gly]+ with ninhydrin has been studied spectrophotometrically at 70°C and pH 5.0. The reaction follows first‐ and fractional‐order kinetics, respectively, in complex and ninhydrin. The reaction is catalyzed by CTAB micelles, and the maximum rate enhancement is about twofold. The results obtained in the micellar medium are treated quantitatively in terms of the kinetic pseudophase and Piszkiewicz models. The rate constants (kobs or kΨ), micellar‐binding constants (kS for [Cu(II)‐Gly‐Gly]+, kN for ninhydrin), and index of cooperativity (n) have been evaluated. A mechanism is proposed in accordance with the experimental results. The influence of different inorganic (NaCl, NaBr, Na2SO4) and organic (NaBenz, NaSal) salts on the reaction rate has also been seen, and it is found that tightly bound/incorporated counterions are the most effective. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 556–564, 2007
Regularized meshless method for antiplane shear problems with multiple inclusions
Authors: Chen K. H. , Chen J. T. , Kao J. H. 
Published: July 2007

AbstractIn this paper, we employ the regularized meshless method to solve antiplane shear problems with multiple inclusions. The solution is represented by a distribution of double‐layer potentials. The singularities of kernels are regularized by using a subtracting and adding‐back technique. Therefore, the troublesome singularity in the method of fundamental solutions (MFS) is avoided and the diagonal terms of influence matrices are determined. An inclusion problem is decomposed into two parts: one is the exterior problem for a matrix with holes subjected to remote shear, the other is the interior problem for each inclusion. The two boundary densities, essential and natural data, along the interface between the inclusion and matrix satisfy the continuity and equilibrium conditions. A linear algebraic system
is obtained by matching boundary conditions and interface conditions. Finally, numerical results demonstrate the accuracy of the present solution. Good agreements are obtained and compare well with analytical solutions and Gong's results. Copyright © 2007 John Wiley & Sons, Ltd.
Coupling of a non‐overlapping domain decomposition method for a nodal finite element method with a boundary element method
Authors: Boubendir Y. , Bendali A. , Fares M. B. 
Published: July 2007

AbstractNon‐overlapping domain decomposition techniques are used to solve the finite element equations and to couple them with a boundary element method. A suitable approach dealing with finite element nodes common to more than two subdomains, the so‐called cross‐points, endows the method with the following advantages. It yields a robust and efficient procedure to solve the equations resulting from the discretization process. Only small size finite element linear systems and a dense linear system related to a simple boundary integral
equation are solved at each iteration and each of them can be solved in a stable way. We also show how to choose the parameter defining the augmented local matrices in order to improve the convergence. Several numerical simulations in 2D and 3D validating the treatment of the cross‐points and illustrating the strategy to accelerate the iterative procedure are presented. Copyright © 2007 John Wiley & Sons, Ltd.