bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of biodegradable elastomeric scaffolds with sub‐micron morphologies
Authors: Stankus John J. , Guan Jianjun , Wagner William R. 
Published: July 2004

AbstractThe native extracellular matrix (ECM) of elastic tissues is strong and flexible and supports cell adhesion and enzymatic matrix remodeling. In an attempt to convey these ECM properties to a synthetic scaffold appropriate for soft tissue engineering applications, a biodegradable, elastomeric poly(ester urethane)urea (PEUU) was combined with type I collagen at various ratios (2.5, 5, 10, 20, 50, 60, 70, 80, and 90 wt% collagen) and electrospun to construct elastic matrices. Randomly orientated fibers in the electrospun matrices ranged in diameter from 100–900 nm, dependent on initial polymer concentration. Picrosirius red staining of matrices and CD spectroscopy of released collagen confirmed collagen incorporation and preservation of collagen structure at the higher collagen mass fractions. Matrices were strong and distensible possessing strengths of 2–13 MPa with breaking strains of 160–280% even with low PEUU content. Collagen incorporation significantly enhanced smooth muscle cell adhesion onto electrospun scaffolds. An approach has been demonstrated that mimics elastic extracellular matrices by using a synthetic component to provide mechanical function together with a biomacromolecule, collagen. Such matrices may find application in engineering soft tissue. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 603–614, 2004
Evaluation of wear resistance of dental resin composites with a 3D profilometer
Authors: Cha Hyun‐Suk , Lee Yong‐Keun , Lim Bum‐Soon , Rhee Sang‐Hoon , Yang Hyeong‐Cheol 
Published: July 2004

AbstractThe objectives of this study were to determine the wear resistance of dental resin composites, and to evaluate the influence of wear‐simulating apparatus on wear. Nine commercial resin composites were studied. Wear was simulated with an oral wear simulator (Proto‐Tech), which simultaneously incorporates the wear mechanism of attrition and abrasion in three‐body wear mode, and with a pin‐on‐disk type friction tester (Rhesca, Japan). Composite specimens were subjected to 50,000 cycles of wear against a dental porcelain antagonist. After wear simulation, parameters for the determination of wear amount, such as wear volume, maximum wear depth, mean of maximum wear depth, and average wear depth were measured with the use of a 3D profilometer. For the oral wear simulator, the range of wear volume was 4.3–9.2 × 10−2 mm3, and there were significant differences among the composites (p < 0.05). In other parameters, there were no significant differences among the composites. For the pin‐on‐disk tester, the range of mean of maximum wear depth was 7.5–26.3 μm, which was significantly different among the composites (p < 0.05). Correlation coefficient (r) between the wear volume from the oral wear simulator and the mean of maximum wear depth from the pin‐on‐disk tester was 0.52. Conclusively, dental resin composites showed significantly different wear resistance. Wear simulating apparatus influenced the amount of wear, and suitable parameters for the determination of wear amounts should be selected in each apparatus. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 414–420, 2004
Is hydroxyapatite cement an alternative for allograft bone chips in bone grafting procedures? A mechanical and histological study in a rabbit cancellous bone defect model
Authors: Voor M. J. , Arts J. J. C. , Klein S. A. , Walschot L. H. B. , Verdonschot N. , Buma P. 
Published: July 2004

AbstractTo evaluate in vivo performance of hydroxyapatite cement (HAC) as a porous bone graft substitute, HAC was mixed (1:1 ratio) with either porous calcium‐phosphate granules (80% tricalcium phosphate, 20% hydroxyapatite) or defatted morsellized cancellous bone (MCB) allograft and implanted bilaterally in cylindrical drill holes in distal femurs of rabbits. Groups with empty defects and impacted MCB were used for reference. After 8 weeks, one femur from each pair was examined histologically. All contralateral specimens and Time‐0 specimens were used for mechanical indentation tests. Histology showed that some empty defects were filled with newly formed osteopenic bone after 8 weeks. The impacted MCB showed remodeling into new vital bone. Incorporation of the HAC/MCB composite was incomplete, whereas minimal new bone ingrowth was found in the HAC/granule composites. Though not different from each other, both composites were significantly stronger than empty defects, incorporated impacted MCB, and intact cancellous bone. At Time 0, the mechanical behavior of impacted MCB was similar to both HAC composites. In conclusion, composites of HAC and porous biomaterials can maintain relatively high strength over 8 weeks in vivo, but their incorporation into a new bony structure is slower than impacted MCB. The HAC/MCB composite showed favorable incorporation behavior. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 398–407, 2004
NAP‐2 is part of multi‐protein complexes in Hela cells
Authors: Rodriguez Pedro , Ruiz Marcia T. , Price Gerald B. , Zannis‐Hadjopoulos Maria 
Published: July 2004

AbstractWe previously reported that a complex of nuclear proteins from HeLa cells, among them histone H1 and casein kinase 2 co‐eluted from immobilized nucleosome assembly protein 2 (NAP‐2)‐Sepharose. Here, using HeLa cell nuclear extracts, we found NAP‐2 migrates in a blue‐native polyacrylamide gel with an apparent molecular weight of 300 kDa. HeLa cell NAP‐2, labeled in vivo with radioactive orthophosphate, co‐precipitated with at least two phosphoproteins, with an apparent mass of 100 and 175 kDa, respectively, as determined by SDS–PAGE. NAP‐2 from total HeLa cell extract co‐purified with other proteins through two sequential chromatographic steps: first, a positively charged resin, Q‐Sepharose, was used, which purified NAP‐2 more easily with other proteins that eluted as a single peak at 0.5 M NaCl. This fraction possessed both relaxing and supercoiling activities, and it was able to assemble regularly spaced nucleosomes onto naked DNA in an ATP‐dependent manner. Second, a negatively charged resin (heparin) was used, which retained small amounts of NAP‐2 (a very acidic polypeptide) and topoisomerase I. This fraction, although able to supercoil relaxed DNA, did so to a lesser extent than the Q‐Sepharose fraction. The data suggest that NAP‐2 is in complex(es) with other proteins, which are distinct from histones. © 2004 Wiley‐Liss, Inc.
Involvement of phosphoinositide 3‐kinase signaling pathway in chondrocytic differentiation of ATDC5 cells: Application of a gene‐trap mutagenesis
Authors: Ihara‐Watanabe Miyuki , Uchihashi Takayuki , Miyauchi Yoshiteru , Sakai Norio , Yamagata Masayo , Ozono Keiichi , Michigami Toshimi 
Published: July 2004

AbstractGene‐trap mutagenesis is based on the notion that the random insertion of a trapping vector may disturb the function of inserted genes. Here, we applied this method to murine mesenchymal ATDC5 cells, which differentiate into mature chondrocytes in the presence of insulin. As the trap vector we used pPT1‐geo, which lacks its own promoter and enhancer, but contains a lacZ–neo fusion gene as a reporter and selection marker driven by the promoter of the trapped gene. After pPT1‐geo was introduced into ATDC5 cells by electroporation, the neomycin‐resistant clones were screened for β‐galactosidase activity. The selected clones were cultured in differentiation medium to evaluate the chondrogenic phenotype. The clones no. 6–30 and 6–175, which exhibited impaired and accelerated mineralization, respectively, were subjected to further analysis. In clone no. 6–30 in which the gene coding for the p85α subunit of phosphoinositide 3‐kinase (PI3K) was trapped, the expression of marker genes of early chondrocytes including collagen type II, aggrecan, and PTH/PTHrP receptor was delayed. The insulin‐induced stimulation of growth was reduced in clone no. 6–30 compared with the parental ATDC5 cells. Moreover, treatment of parental ATDC5 cells with a specific inhibitor of PI3K, LY294002, phenocopied clone no. 6–30, suggesting the involvement of PI3K signaling in the chondrogenic differentiation of ATDC5 cells. Clone no. 6–175 with accelerated mineralization was revealed to have a gene homologous to human KIAA0312 trapped, whose function remains unclear. Taken together, the gene‐trap in ATDC5 cells might be useful to identify the molecules involved in chondrogenic differentiation. © 2004 Wiley‐Liss, Inc.
Differences in production of melanin radicals by 694 nm ruby laser and UVA radiation
Authors: Haywood Rachel M. , Linge Claire 
Published: July 2004

AbstractBackground and ObjectivesThe 694 nm ruby laser is used clinically for hair removal and the mechanism is predominantly photo thermal via melanin targeting. We investigated 694 nm laser‐irradiation of human hair, and laser‐irradiation of synthetic dopa melanin to establish whether photolysis and oxygen radical production is also contributory, and which may have side effects.Study Design/Materials and MethodsUltraviolet‐A (UVA) irradiation of melanin was used as a positive control for radical production. Laser‐ and UVA‐irradiated hair samples, and synthetic dopa melanin in media of different viscosity, were analyzed using electron spin resonance spectroscopy, and compared. The spin trap 5,5‐dimethyl‐ 1‐pyrroline N‐oxide (DMPO) was used to probe laser‐irradiated dopa melanin for superoxide radical production.ResultsComparable to UVA, laser‐irradiation of hair increased the signal‐intensity of the intrinsic melanin radical. UVA‐induced radicals decay rapidly; however, laser‐induced radicals decayed slowly and did not fully revert to original levels after 24 hours. Laser‐induced radicals were increasingly stable with viscosity of the medium. Superoxide radicals were detected using DMPO in UVA‐ but not laser‐irradiated synthetic dopa‐melanin at pH 4.5.ConclusionsLaser‐irradiation of melanin does not result in oxygen radical formation; however, a paramagnetic species, long‐lived in rigid media, is detected which is worth further investigation. Lasers Surg. Med. 35:77–83, 2004. © 2004 Wiley‐Liss, Inc.
Theoretical and experimental investigation of the thermal effects within body cavities during transendoscopical CO2 laser‐based surgery
Authors: Dayan Abraham , Goren Alon , Gannot Israel 
Published: July 2004

AbstractBackground and ObjectivesThe recent development of flexible hollow waveguides for MID‐IR lasers may be utilized transendoscopically to ablate selectively neoplastic, superficial tissues within body cavities. Study goals are to investigate theoretically and experimentally heat distribution and thermal response of cavity lining, during CO2 laser minimally invasive surgery (MIS), and to thermally optimize the procedure under practical conditions.Study Design/Materials and MethodsMathematical model was developed to predict temperature distribution along cavity lining. Experimental setup was built, including all the necessary components for a fully feedback‐controlled MIS, i.e., laser generator, gas insufflating system, surgical suction, and infrared imaging feedback mechanism, all controlled by central PC‐based program. Thermal images of cavity lining were recorded and analyzed throughout varying conditions.ResultsThermal gradients along the cavity lining, during and after the laser irradiation, were obtained mathematically and experimentally. Diverse modes of heat dispersions were observed, as well as the relative contributions of user‐controlled parameters to the maximal heat of cavity lining. The software‐controlled setup has demonstrated the capacity to instantly manage varying conditions, by which it automatically protects cavity lining from getting overheated.ConclusionsAnalytical predictions and experimental measurements were highly correlated. The software‐controlled system may serve a powerful tool to control thermal side effects during MIS within body cavities. Lasers Surg. Med. 35:18–27, 2004. © 2004 Wiley‐Liss, Inc.
Scanning electron microscopic evaluation of resin–dentin interface after Er:YAG laser preparation
Authors: Bertrand Marie‐France , Hessleyer Daniel , Muller‐Bolla Michèle , Nammour Samir , Rocca Jean‐Paul 
Published: July 2004

AbstractBackground and ObjectivesThe aim of this study was to observe the morphological characteristics of dentin–resin interfaces when a composite resin was bonded to Er:YAG laser irradiated dentin.Study Design/Materials and MethodsHuman dentin surfaces were divided into three equal areas. One third was prepared using a carbide bur and etched with phosphoric acid, the second third was conditioned using an Er:YAG laser, the third one was irradiated and etched. A hybrid composite resin was bonded on dentin surfaces using a single‐component adhesive system. Longitudinal sections were exposed to 5 N HCl then to 1% NaOCl. The thickness of the hybrid layer and the dimensions of the resin tags were measured using scanning electron microscopy (SEM) pictures and an image analysis software.ResultsWhen acid etching was performed, a hybrid layer as well as the characteristic funnel‐shaped resin tags were observed. When Er:YAG laser was used alone, no hybrid layer could be detected. The resin tags appeared thinner and exhibited a cylindrical shape.ConclusionsThe acid pre‐treatment of the irradiated surface allowed both the seal of the dentinal surface and the increase of the diameter of the resin tags. Lasers Surg. Med. 35:51–57, 2004. © 2004 Wiley‐Liss, Inc.
Closure of skin incisions in rabbits by laser soldering: I: Wound healing pattern
Authors: Simhon David , Brosh Tamar , Halpern Marisa , Ravid Avi , Vasilyev Tamar , Kariv Naam , Katzir Abraham , Nevo Zvi 
Published: July 2004

AbstractBackground and ObjectivesTemperature‐controlled tissue laser soldering is an innovative sutureless technique awaiting only solid experimental data to become the gold‐standard surgical procedure for incision closure. The goals of the current study were: (1) to define the optimal laser soldering conditions, (2) to explore the immediate skin reparative healing events after sealing the wound, and (3) to determine the long‐term trajectory of skin wound healing.Study Design/Materials and MethodsSkin incisions were generated over rabbit dorsa and were closed using different wound‐closure interventions, in three groups: (a) closure, using a temperature‐controlled infrared fiberoptic CO2 laser system, employing 47% bovine serum albumin as a solder; (b) wound closure by cyanoacrylate glues; and (c) wound closure by sutures. The reparative outcomes were evaluated macroscopically and microscopically, employing semi‐quantitative grading indices.ResultsLaser soldering of incisions at T = 65°C emerged as the optimal method achieving immediate wound sealing. This in turn induced accelerated reparative events characterized by a reduced inflammatory reaction, followed by minimal scarring and leading to a fine quality healing.ConclusionsTemperature‐controlled laser soldering offers an accelerated wound reparative process with numerous advantages over the conventional methods. Further investigations may reveal additional benefits in the spectrum of advantages that this innovative surgical technology has to offer. This can introduce new scientific insight that will pave the way for clinical use. Lasers Surg. Med. 35:1–11, 2004. © 2004 Wiley‐Liss, Inc.
Thermosetting Blends of Polybenzoxazine and Poly(ε‐caprolactone): Phase Behavior and Intermolecular Specific Interactions
Authors: Zheng Sixun , Lü Han , Guo Qipeng 
Published: July 2004

AbstractSummary: Polybenzoxazine (PBA‐a)/poly(ε‐caprolactone) (PCL) blends were prepared by an in situ curing reaction of benzoxazine (BA‐a) in the presence of PCL. Before curing, the benzoxazine (BA‐a)/PCL blends are miscible, which was evidenced by the behaviors of single and composition‐dependant glass transition temperature and equilibrium melting point depression. However, the phase separation induced by polymerization was observed after curing at elevated temperature. It was expected that after curing, the PBA‐a/PCL blends would be miscible since the phenolic hydroxyls in the PBA‐a molecular backbone have the potential to form intermolecular hydrogen‐bonding interactions with the carbonyls of PCL and thus would fulfil the miscibility of the blends. The resulting morphology of the blends prompted an investigation of the status of association between PBA‐a and PCL under the curing conditions. Although Fourier‐transform infrared spectroscopy (FT‐IR) showed that there were intermolecular hydrogen‐bonding interactions between PBA‐a and PCL at room temperature, especially for the PCL‐rich blends, the results of variable temperature FT‐IR spectroscopy by the model compound indicate that the phenolic hydroxyl groups could not form efficient intermolecular hydrogen‐bonding interactions at elevated temperatures, i.e., the phenolic hydroxyl groups existed mainly in the non‐associated form in the system during curing. The results are valuable to understand the effect of curing temperature on the resulting morphology of the thermosetting blends.SEM micrograph of the dichloromethane‐etched fracture surface of a 90:10 PBA‐a/PCL blend showing a heterogeneous morphology.magnified imageSEM micrograph of the dichloromethane‐etched fracture surface of a 90:10 PBA‐a/PCL blend showing a heterogeneous morphology.
Continuous dependence on modelling for a complex Ginzburg–Landau equation with complex coefficients
Authors: Yang Yongfu , Gao Hongjun 
Published: July 2004

AbstractContinuous dependence on a modelling parameter is established for solutions of a problem for a complex Ginzburg–Landau equation. A homogenizing boundary condition is also used to discuss the continuous dependence results. We derive a priori estimates that indicate that solutions depend continuously on a parameter in the governing differential equation. Copyright © 2004 John Wiley & Sons, Ltd.
A regularity result for stationary electrorheological fluids in two dimensions
Authors: Bildhauer Michael , Fuchs Martin 
Published: July 2004

AbstractWe proveC1,α‐regularity for the strong solution to a non‐linear system of partial differential equations modeling electrorheological fluids in the stationary case which has been constructed by Ettwein and Ettwein‐Růžička [Elektrorheologische Flüssigkeiten: Existenz starker Lösungen in zweidimensionalen Gebieten. Diplomarbeit, Universität Freiburg, 2002;Geometric Analysis and Nonlinear Partial Differential Equations, Hildebrandt S, Karcher H (eds). Springer: Berlin–Heidelberg–New York, 2003; 591–602]. Copyright © 2004 John Wiley & Sons, Ltd.
Service delivery in francophone West Africa: the challenge of balancing deconcentration and decentralisation
Authors: Pinto Rogerio F. 
Published: July 2004

AbstractThe article reviews the experiences with decentralisation of one West African country, Guinea, with the intent of drawing lessons and exploring approaches to assist countries in the sub‐region in rendering decentralisation—an effective means for service delivery improvements. Section II describes the West Africa context in terms of the dynamics of deconcentration–decentralisation and lays out a conceptual framework to guide the analytical assessment of countries in the sub‐region, attempting to decentralise. This framework is used in the Guinea case, described in Section III. Section IV concludes by synthesising the profile of Guinea, and positions its dominant style in relation to the proposed ideal types of decentralisation approaches. This part of the article discusses the implications of its findings for decentralisation policy and implementation, and offers some remarks on the road ahead for decentralisation in West Africa. Copyright © 2004 John Wiley & Sons, Ltd.
Use of menopausal hormones in the United States, 1992 through June, 2003
Authors: Wysowski Diane K. , Governale Laura A. 
Published: July 2004

AbstractPurposeThe Women's Health Initiative (WHI) study that documented an unfavorable benefit to risk ratio of Prempro and subsequently an increased risk of stroke with menopausal estrogen prompted us to investigate the use during 1992 through June 2003 of menopausal hormones in the United States.MethodsTwo pharmaceutical research databases from IMS Health, the National Prescription Audit Plus™ and the National Disease and Therapeutic Index™, were accessed and analyzed.ResultsThe number of dispensed outpatient prescriptions for oral menopausal estrogens and oral combination estrogen–progestins increased 2.5‐fold (153%) from 34.5 million dispensed in 1992 to a high of 87.3 million in 2000. For July 2002 through June 2003, the year following the publication of the results of the WHI trial, prescriptions for these products declined to 59.6 million, a 32% decrease from their peak in 2000. Prescriptions for transdermal estrogen and transdermal combination estrogen–progestin products increased from 5.2 million dispensed in 1992 to their peak of 8.3 million in 2000, and declined 10% to 7.5 million during July 2002 through June 2003. By contrast, prescriptions for oral menopausal progestins rose to 17.5 million in 1995 and then steadily declined. In the year after the WHI, prescriptions for oral progestins decreased 49% to 8.9 million from their peak in 1995. The earlier decline in oral progestin prescriptions was primarily due to the marketing in 1995 of the popular oral combination estrogen–progestin drugs.ConclusionsPrescriptions dispensed for menopausal hormones increased substantially between 1992 and peaked in 2000. By June 2003, prescriptions for oral menopausal estrogens and oral combination estrogen–progestins had declined by about one‐third from their peak year. Published in 2004 by John Wiley & Sons, Ltd.
Visual observation of CO2 foaming of polypropylene‐clay nanocomposites
Authors: Taki Kentaro , Yanagimoto Tatsunori , Funami Eita , Okamoto Masami , Ohshima Masahiro 
Published: July 2004

AbstractUsing a newly developed high‐pressure autoclave, which has two sapphire windows on the walls, we visually observed the batch physical foaming of polymer‐clay nanocomposites to understand the effect of nano‐sized clay on the initial stage of foaming. With CO2 as a physical foaming agent, polypropylene‐montmorillonite clay nanocomposites were foamed at 150°C. A high‐speed digital camera with a microscope could observe the bubble nucleation and bubble growth behavior of the early stage of foaming in situ. The series of micrographs was analyzed in order to investigate the effect of clay content on bubble nucleation and growth. The experiments, together with CO2‐solubility and diffusivity data, show that the clay enhances bubble nucleation as a nucleation agent and retards the growth of bubbles at the early stage of foaming. Polym. Eng. Sci. 44:1004–1011, 2004. © 2004 Society of Plastics Engineers.