bluuebunny/crossref_metadata_2025_split huggingface dataset:
A structural model of US aggregate job flows
Authors: Collard Fabrice , Fève Patrick , Langot François , Perraudin Corinne 
Published: October 2002

AbstractThis paper contributes to the analysis of jobs flows dynamics through the explicit modelling of job creations and job destructions. We propose a simple matching model extended for endogenous separation and tractable heterogeneity. The parameters of the model are estimated using a simulation‐based estimation method. We then test the ability of trade externalities, generated by the matching process, to (i) propagate reallocation and aggregate disturbances in the whole labor market and (ii) generate the observed distribution of aggregate job flows. The results clearly indicate that the model is able to match the dynamics of US aggregate job flows. Copyright © 2002 John Wiley & Sons, Ltd.
Oestrogenic activity of isobutylparaben in vitro and in vivo
Authors: Darbre P. D. , Byford J. R. , Shaw L. E. , Horton R. A. , Pope G. S. , Sauer M. J. 
Published: October 2002

AbstractThe alkyl esters of p‐hydroxybenzoic acid (parabens) are used widely as preservatives in foods, pharmaceuticals and cosmetics to which the human population is exposed. Recent studies have reported that methylparaben, ethylparaben, n‐propylparaben and n‐butylparaben all possess oestrogenic activity in several in vitro assays and in animal models in vivo. This study reports on the oestrogenic activity of isobutylparaben in a panel of assays in vitro and in vivo. Isobutylparaben was able to displace [3H]oestradiol from cytosolic oestrogen receptor α of MCF7 human breast cancer cells by 81% at 100 000‐fold molar excess. Using a clonal line of MCF7 cells containing a stably transfected oestrogen‐responsive ERE‐CAT reporter gene, CAT gene expression could be increased by isobutylparaben such that the magnitude of the response was the same at 10−5 M isobutylparaben as with 10−8 M 17β‐oestradiol. Isobutylparaben could also increase expression of the endogenous oestrogen‐responsive pS2 gene in MCF7 cells and maximal expression at 10−5 M isobutylparaben could be inhibited with the anti‐oestrogen ICI 182 780. The proliferation of two oestrogen‐dependent human breast cancer cell lines MCF7 and ZR‐75‐1 could be increased with isobutylparaben such that at concentrations of 10−5 M the proliferation response was of the same magnitude as with 10−8 M 17β‐oestradiol. Evidence for oestrogen receptor mediation of proliferation effects was provided by the inability of isobutylparaben to influence the growth of oestrogen‐unresponsive MDA‐MB‐231 human breast cancer cells and by the ability of the anti‐oestrogen ICI 182 780 to inhibit the isobutylparaben effects on MCF7 cell growth. The proliferation response to 10−10 M 17β‐oestradiol was not antagonized with isobutylparaben at any concentration from 10−9 M to 10−4 M in either MCF7 or ZR‐75‐1 cells. Finally, subcutaneous administration of isobutylparaben was able to increase the uterine weight in the immature mouse after three daily doses of 1.2 or 12.0 mg per mouse. Previous work using linear‐alkyl‐chain parabens has shown that oestrogenic activity increases with alkyl chain length from methylparaben to n‐butylparaben. The results here show that branching of the alkyl chain to isobutylparaben increases oestrogenic activity beyond that of the equivalent length linear alkyl chain in n‐butylparaben. Copyright © 2002 John Wiley & Sons, Ltd.
Ion leaching from dental ceramics during static in vitro corrosion testing
Authors: Milleding Percy , Haraldsson Conny , Karlsson Stig 
Published: October 2002

AbstractDental ceramics are often called inert materials. It can be hypothesized, however, that differences in the composition, microstructure, and environmental conditions will affect the degree of corrosion degradation in an aqueous environment. The aims of the study were, therefore, to study the ion dissolution from glass‐phase ceramics, with or without crystalline inclusions, and from all‐crystalline ceramics and to compare the effects of different corrosion media. Ceramic specimens were produced from glass‐phase and oxide ceramics and given an equivalent surface smoothness, after which they were subjected to in vitro corrosion (Milli‐Q water at 37 ± 2°C for 18 h and 4% acetic acid solution at 80 ± 2°C for 18 h, respectively). The temperature of the corrosion solution was slowly increased until it reached 80 ± 2°C to reduce the risk of microcrack formation at the surface. The analyses of ion leakage were performed with inductively coupled plasma optical emission spectroscopy. A large number of inorganic elements leached out from the various dental ceramics. The major leaching elements were sodium and potassium; in the acid‐corrosion experiments, there were also magnesium, silicon, and aluminum and, on a lower scale, yttrium, calcium, and chromium. The various glass‐phase ceramics displayed significant differences in ion leakage and significantly higher leakage values than all‐crystalline alumina and zirconia ceramics. No significant difference in dissolution was found between high and low‐sintering glass‐phase ceramics or between glass‐phase ceramics with high volume fractions of crystallites in the glass phase in comparison with those with lower crystalline content. It can be concluded, therefore, that none of the dental ceramics studied are chemically inert in an aqueous environment. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 541–550, 2002
Thin film rheology and lubricity of hyaluronic acid solutions at a normal physiological concentration
Authors: Tadmor Rafael , Chen Nianhuan , Israelachvili Jacob N. 
Published: October 2002

AbstractUsing a surface forces apparatus to measure forces, and optical (multiple beam) interferometry to measure surface shapes and separations (to ±1 Å), the normal, viscous, and shear (lubrication) forces between smooth mica surfaces in aqueous hyaluronic acid (HA) solutions were measured. The experimental conditions of loading pressures, pH, and HA concentration were set to closely correspond to physiological human knee‐joint conditions. From the force and optical (refractive index) measurements, it was concluded that, like other negatively charged polyelectrolytes, HA does not naturally adsorb on the mica surface which is hydrophilic and weakly negatively charged at physiological conditions: the polymer solution exhibits the bulk viscosity (22.5 ± 1.5 cP) for films thicker than about 0.4 μm of the polymer, whereas for thinner films, the viscosity decreases monotonically toward the value of the pure electrolyte solution (1 cP) as HA is extruded from between the surfaces. This is indicative of a repulsive “depletion” interaction of HA with each mica surface and to a weakly attractive polymer‐mediated force between the two surfaces. Thus, free HA in synovial fluid is not expected to act as a good “boundary lubricant.” Relaxation measurements on approaching and receding surfaces in HA solutions were also performed, and it is shown that the presence of HA in the bulk solution can improve “hydrodynamic” modes of lubrication, for example, by assuaging the compression stroke. The study includes information that is beneficial to researchers working with biomaterials viscosupplementation devices. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 514–523, 2002
Polymer–calcium phosphate cement composites for bone substitutes
Authors: Mickiewicz Rafal A. , Mayes Anne M. , Knaack David 
Published: October 2002

AbstractThe use of self‐setting calcium phosphate cements (CPCs) as bioresorbable bone‐replacement implant materials presently is limited to non‐load‐bearing applications because of their low compressive strength relative to natural bone. The present study investigated the possibility of strengthening a commercially available CPC, α‐BSM™, by incorporating various water‐soluble polymers into the cement paste during setting. Several polyelectrolytes, poly(ethylene oxide), and the protein bovine serum albumin (BSA) were added in solution to the cement paste to create calcium phosphate–polymer composites. Composites formulated with the polycations poly(ethylenimine) and poly(allylamine hydrochloride) exhibited compressive strengths up to six times greater than that of pure α‐BSM™ material, with a maximum value reached at intermediate polymer content and for the highest molecular weight studied. Composites containing BSA developed compressive strengths twice that of the original cement at protein concentrations of 13–25% by weight. In each case, XRD studies correlate the improvement in compressive strength with reduced crystallite dimensions, as evidenced by a broadening of the (0,0,2) reflection. This suggests that polycation or BSA adsorption inhibits crystal growth and possibly leads to a larger crystal aspect ratio. SEM results indicate a denser, more interdigitated microstructure. The increased strength was attributed to the polymer's capacity to bridge between multiple crystallites (thus forming a more cohesive composite) and to absorb energy through plastic flow. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 581–592, 2002
Repair of segmental defects in rabbit humeri with titanium fiber mesh cylinders containing recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and a synthetic polymer
Authors: Murakami Narumichi , Saito Naoto , Horiuchi Hiroshi , Okada Takao , Nozaki Kazutoshi , Takaoka Kunio 
Published: October 2002

AbstractTo develop a new technology that enhances the regeneration potential of bone and the repair of large intercalated defects in long bone, recombinant human bone morphogenetic protein‐2 (BMP‐2; 20 μg or 40 μg) was mixed in a polymer gel (poly‐lactic acid‐polyethyleneglycol block copolymer; PLA‐PEG; 200 mg) and incorporated into titanium fiber‐mesh cylinders. Three 5‐mm cylinders were placed end‐to‐end to fill a 15‐mm defect created in the humeri of adult rabbits and were stabilized by an intramedullary rod. In controls, the titanium fiber‐mesh cylinders were combined with PLA‐PEG in the absence of BMP. Six weeks after implantation, new bone had formed on the surface of the implant and had bridged the defect. All of the defects (5/5) treated by cylinders containing 120 μg (40 μg × 3) of BMP were repaired completely. New bone formation was also found inside the pores of the cylinders. The defect was not repaired in the control animals. These results demonstrate that these new composite implants fabricated by combining rhBMP, synthetic degradable polymers and compatible biomaterials enhance the regeneration potential of bone. Thus, it is possible that large skeletal defects can be repaired using this prosthesis in lieu of autogenous bone graft. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 169–174, 2002
In vitro change in mechanical strength of β‐tricalcium phosphate/copolymerized poly‐L‐lactide composites and their application for guided bone regeneration
Authors: Kikuchi Masanori , Koyama Yoshihisa , Takakuda Kazuo , Miyairi Hiroo , Shirahama Noriaki , Tanaka Junzo 
Published: October 2002

AbstractNovel composites of bioactive β‐tricalcium phosphate [Ca3(PO4)2] and biodegradable copolymerized poly‐L‐lactide (CPLA) were prepared by a heat‐kneading method. The mechanical and chemical changes of the composites were evaluated in vitro by soaking in physiological saline and Dulbecco's phosphate buffered saline. When soaked in physiological saline, the 3‐point mechanical strength decreased rapidly from 60 to 30 MPa in the initial 4 weeks and then gradually reached a plateau; the initial decrease in the mechanical strength was ascribed to the dissolution of β‐tricalcium phosphate from the surface. The mechanical properties evident at 8–12 weeks were sufficient for the composites to be used as a biodegradable material for regeneration of bone because the hydrolysis of CPLA was inhibited in both physiological saline and phosphate‐buffered saline as a result of a pH‐buffering effect. Composite membranes 250‐μm thick were used to regenerate large bone defects in beagle dogs: 10 × 10 × 10 mm3 in volume in the mandible and 20 mm in length in the tibia. The afflicted areas covered with the composite membranes were almost perfectly filled with new bone 12 weeks after the operation, whereas those covered with a CPLA membrane or without any membranes were invaded by soft tissue. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 265–272, 2002
Kinetic study of citric acid influence on calcium phosphate bone cements as water‐reducing agent
Authors: Sarda S. , Fernández E. , Nilsson M. , Balcells M. , Planell J. A. 
Published: October 2002

AbstractMost of the research performed on calcium phosphate bone cements (CPBCs) has dealt with the improvement of bone cement formulations for new, demanding bone‐filling applications. In particular, the development of injectable bone cements is of real interest for the biomedical community. The aim of this work was to study the effect of citric acid on the injectability and the setting properties of alpha‐tricalcium phosphate‐based cements. A comparative kinetic study was performed on cements with and without citric acid relating the hardening curves and the hydration rates using a mathematical approach. Citric acid behaved as a fluidificant during the first stages of the cement mixing. The dissolution‐precipitation reactions of the alpha‐tricalcium phosphate were retarded with the addition of citric acid and the compressive strength at saturation increased. In conclusion, citric acid can behave as a water‐reducing admixture. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 653–659, 2002
Tissue response to microfibers of different polymers: Polyester, polyethylene, polylactic acid, and polyurethane
Authors: Sanders J. E. , Bale S. D. , Neumann T. 
Published: October 2002

AbstractTissue response to single polymer microfibers of polyester (PET), polyethylene (PE), poly(L‐lactic acid) (PLA), and polyurethane (PU) was assessed using a rat subcutaneous model. Fibers of diameters ranging from 1 to 15 μm were aligned parallel to each other on polycarbonate frames and implanted in the subcutaneous dorsum in the subscapular region. After 5 weeks of implantation, fibrous capsule thickness was significantly less for fibers of diameters 1–5 than for those of 11–15 μm for all polymers tested. For PET and PU, 75.0 and 71.4% respectively of the 1–5 μm fibers had no capsule, while for PE and PLA only 45.5 and 56.3% respectively had no capsule. For 1–5 μm fibers, PE had significantly thicker capsules than PET and PU. Reducing fiber diameters from 6–10 to 1–5 μm induced a greater reduction in capsule thickness than changing polymers among PET, PE, and PLA. PU showed the least encapsulation of all polymers, demonstrating significantly thinner capsules than PET, PE, and PLA for 6–10 and 11–15 μm fibers. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 222–227, 2002
Enhancement of osteogenesis on hydroxyapatite surface coated with synthetic peptide (EEEEEEEPRGDT) in vitro
Authors: Itoh D. , Yoneda S. , Kuroda S. , Kondo H. , Umezawa A. , Ohya K. , Ohyama T. , Kasugai S. 
Published: October 2002

AbstractSome dental implants are coated with hydroxyapatite (HA), which preferentially binds to bone. Several matrix proteins have an arginine‐glycine‐aspartic acid (RGD) sequence where cells attach via an integrin receptor. We hypothesized that coating an HA surface with an RGD‐containing peptide might enhance the attachment and differentiation of osteoblasts. The HA disks (diameter 34 mm, thickness 1 mm) were treated with a solution (50 mM Tris/HCl and 150 mM NaCl, pH 7.4) containing the peptide EEEEEEEPRGDT, in which the E repetition exerts a high affinity to HA. After washing with phosphate‐buffered saline, KUSA/A1 mouse osteoblastic cells were inoculated onto the HA surface and cultured. After 30 min, the number of cells attached to the surface was counted. The DNA content and alkaline phosphatase (ALP) activity were measured after 10 days in culture. Expression of bone matrix proteins was also examined by means of reverse transcriptase–polymerase chain reaction at 7 days; the mineralized area of the culture was also evaluated by staining with Alizarin Red S after 10 days. Treatment with the peptide stimulated cell attachment and increased DNA content and ALP activity. Furthermore, matrix protein expression and mineralized nodule formation were enhanced to a greater extent on the peptide‐treated surface than on the nontreated surface. Our results indicate that coating an HA surface with RGD‐containing peptide enhances osteoblast attachment and differentiation. This peptide treatment of HA‐coated implants may stimulate the osseointegration of the implants. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 292–298, 2002
Comparison between modifications of lens proteins resulted from glycation with methylglyoxal, glyoxal, ascorbic acid, and fructose
Authors: Argirova Mariana , Breipohl Winrich 
Published: October 2002

AbstractCataract is generally associated with the breakdown of the lens microarchitecture. Age‐dependent chemical modifications and cross‐linking of proteins are the major pathways for development of lens opacity. The specific alterations in lens proteins caused by glycation with four carbonyl metabolites, fructose, methylglyoxal, glyoxal, and ascorbic acid, were investigated. Decrease in intensity of tryptophan related fluorescence and level of reduced protein sulfhydryl groups, parameters that are indicative for changes in protein conformation, were observed after reaction with all studied carbonyl compounds. Protein carbonyl content, an index for oxidative damage to proteins, was strongly enhanced in methylglyoxal‐treated proteins. Cross‐linking of glycated proteins was confirmed by polyacrylamide electrophoresis. α‐Oxoaldehydes were the most reactive in protein aggregation. They also formed specific chromophores absorbing UV light above 300 nm. Significant loss in lactate dehydrogenase activity resulted from incubation with methylglyoxal, followed by glyoxal and ascorbic acid. The results obtained showed that alterations in lens proteins do not follow the specific reactivity of studied carbonyl compounds. Despite the similarity in chemical structures of α‐oxoaldehydes and ascorbic acid degradation products, they cause specific alterations in lens protein structure with different biological consequences. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:140–145, 2002. DOI 10.1002/jbt.10031
Expression and cellular localization of naturally occurring β estrogen receptors in uterine and mammary cell lines
Authors: Monje Paula , Boland Ricardo 
Published: October 2002

AbstractThe protein ER‐α has been exhaustively characterized in estrogen‐sensitive tissues and cell lines. However, little is known regarding the expression and cellular distribution of the newly identified ER‐β protein. We first quantified the specific estradiol binding site content in the estrogen‐responsive cell lines MCF‐7 (mammary) and SHM (myometrial). In the two cell types, these sites were associated to the expression of both ER‐α and ‐β isoforms. Native ER‐β was visualized to reside inside the nucleus by means of conventional indirect immunofluorescence. The cells expressed ER‐β as a tight ∼50 kDa triplet when resolved by sodium dodecyl sulfate–polyacrylamide gels (SDS–PAGE) and blotted using antibodies mapping different domains of the cloned ER‐β version. When the cells were subjected to homogenization and differential centrifugation, a substantial proportion of ER‐β immunolabeling was localized at membrane subfractions. ER‐β expression and partitioning was confirmed by Ligand blotting assays using estrogen derivatives coupled to different macromolecular tags. However, ER‐α was expressed as the major estrogen binding protein in both cell lines. Similar localization experiments were performed on HeLa cells (cervix). Though usually considered ER‐negative, this cell line displayed basal significant estrogen binding capacity and co‐expression of both ER isoforms. Taken as a whole, the results indicate that ER‐β could be expressed as functional estrogen binding proteins among a dominant population of ER‐α sites in the cell lines under study. J. Cell. Biochem. 86: 136–144, 2002. © 2002 Wiley‐Liss, Inc.
Effects of estrogen on collagen synthesis by cultured human osteoblasts depend on the rate of cellular differentiation
Authors: Ireland Deborah C. , Bord Sharyn , Beavan Siân R. , Compston Juliet E. 
Published: October 2002

AbstractEstrogen is known to act on osteoblasts according to their stage of differentiation and estrogen receptor (ER) isoform expression. The aim of this study was to determine when type I collagen (COL1) synthesis by cultured low‐passage, human bone‐derived osteoblasts (hOBs) is upregulated in response to estrogen. Cell lines from female donors aged 1 and 66 years were cultured for 11 days on collagen in growth medium supplemented with human serum, hydrocortisone, and β‐glycerophosphate. Young‐donor hOBs grew more quickly than old‐donor hOBs and did not mineralize. Old‐donor hOBs formed mineralized nodules 5 days after reaching confluence. Changes in mRNA levels with time for ERs, type I collagen, and alkaline phosphatase reflected the faster differentiation of the old‐donor cells. The ERβ/ERα ratio fell threefold in young‐donor hOBs but rose 300‐fold in old‐donor hOBs. Increased ERβ/ERα ratios prevented ligand‐dependent downregulation of ERα transcription, resulting in reduced proliferation in old‐donor hOBs. Upregulation of COL1 mRNA expression in response to estrogen was confined to intermediate stages of differentiation, resulting in significant increases in COL1 mRNA by estradiol only in young‐donor cells. Since the young and old‐donor hOBs were cultured under identical conditions, our results indicate that the response of hOBs to estrogen is largely dependent on intracellular mechanisms that control the timing of cellular differentiation. © 2002 Wiley‐Liss, Inc.
A fast annealing evolutionary algorithm for global optimization
Authors: Cai Wensheng , Shao Xueguang 
Published: October 2002

AbstractBy combining the aspect of population in genetic algorithms (GAs) and the simulated annealing algorithm (SAA), a novel algorithm, called fast annealing evolutionary algorithm (FAEA), is proposed. The algorithm is similar to the annealing evolutionary algorithm (AEA), and a very fast annealing technique is adopted for the annealing procedure. By an application of the algorithm to the optimization of test functions and a comparison of the algorithm with other stochastic optimization methods, it is shown that the algorithm is a highly efficient optimization method. It was also applied in optimization of Lennard–Jones clusters and compared with other methods in this study. The results indicate that the algorithm is a good tool for the energy minimization problem. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 427–435, 2002; DOI 10.1002/jcc.10029