bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monomer conversion and cytotoxicity of dental composites irradiated with different modes of photoactivated curing
Authors: Tseng Wan‐Yu , Huang Chien‐Hsun , Chen Ruey‐Song , Lee Ming‐Shu , Chen Yi‐Jane , Rueggeberg Frederick A. , Chen Min‐Huey 
Published: April 2007

AbstractThe aim of the study was to compare the monomer conversion and cytotoxicity of two resin composites, Tetric Ceram (TC) and Heliomolar (HM), irradiated with a halogen light‐curing unit (Optilux 501) using a number of curing modes, boost (OB), ramp (OR), and conventional (OC), as well as a light‐emitting diode (LED) curing unit (LEDemetron; LEDe). The effects of irradiation times (10, 20, 30, and 40 s) were also investigated. The monomer conversion of resin composites was measured using Fourier transform infrared (FTIR) analysis. Resin samples were preimmersed in Dulbeco's modified engles medium (DMEM) for 24 h, and the periodontal ligament cells (PDL) were cultured with aged medium for 72 h to evaluate the cytotoxic effects of resin samples using the microtiter‐tetrazolium (MTT) method. The spectral outputs of the curing units were also compared. After irradiation using the same curing mode, the TC monomer conversion was higher than the HM analog. The TC conversion value was lower after OC and LEDemetron irradiation for 10 s compared to exposures of 30 and 40 s. The HM conversion value was lowest for the 10‐s OC irradiation, and highest for the 40‐s OC exposure. In cytotoxicity tests, the negative control group was without irradiation. The succinate dehydrogenase (SDH) activities of the OB and OR‐irradiated TC samples were significantly lower than analogs irradiated with LEDemetron for 40 s; however, no significant differences were demonstrated between OB, OR, and control groups. Further, no significant differences in SDH activity were demonstrated for OB, OR, and control groups of the HM. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007
Strontium‐substituted apatite coating grown on Ti6Al4V substrate through biomimetic synthesis
Authors: Oliveira A. L. , Reis R. L. , Li P. 
Published: April 2007

AbstractDuring the last few years Strontium has been shown to have beneficial effects when incorporated at certain doses in bone by stimulating bone formation. It is believed that its presence locally at the interface between an implant and bone will enhance osteointegration and therefore, ensure the longevity of a joint prosthesis. In this study we explore the possibility of incorporating Sr into nano‐apatite coatings prepared by a solution‐derived process according to an established biomimetic methodology for coating titanium based implants. The way this element is incorporated in the apatite structure and its effects on the stereochemistry and morphology of the resulting apatite layers was investigated, as well as its effect in the mineralization kinetics. By using the present methodology it was possible to incorporate increasing amounts of Sr in the apatite layers. Sr was found to incorporate in the apatite layer through a substitution mechanism by replacing Ca in the apatite lattice. The presence of Sr in solution induced an inhibitory effect on mineralization, leading to a decrease in the thickness of the mineral layers. The obtained Sr‐substituted biomimetic coatings presented a bone‐like structure similar to the one found in the human bone and therefore, are expected to enhance bone formation and osteointegration. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007
Sol gel derived SiO2‐CaO‐MgO‐P2O5 bioglass system—Preparation and in vitro characterization
Authors: Balamurugan A. , Balossier G. , Michel J. , Kannan S. , Benhayoune H. , Rebelo A. H. S. , Ferreira J. M. F. 
Published: April 2007

AbstractThe synthesis of SiO2‐CaO‐MgO‐P2O5 bioactive glass was carried out by the sol‐gel method. Sol‐gel derived bioglass material was crushed into powder to produce pellet disks by uniaxial pressing, followed by sintering at 900°C. The biocompatibility evaluation of the formed glass was assessed through in vitro cell culture experiments and immersion studies in simulated body fluid (SBF) for different time intervals while monitoring the pH changes and the concentration of calcium and magnesium in the SBF medium. Scanning electron microscopy, X‐ray energy dispersive spectroscopy, X‐ray diffraction analysis, and FT‐IR spectroscopy studies were conducted before and after contact of the material with SBF. At first, an amorphous calcium phosphate was formed; after 21 days this surface consisted of deposited crystalline spheres of apatite. The present investigation also revealed that the sol‐gel derived quaternary bioglass system has the ability to support the growth of osteoblast‐like cells in vitro and to promote osteoblast differentiation by stimulating the expression of major phenotypic markers. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007
Growth of osteoblast‐like cells on biomimetic apatite‐coated chitosan scaffolds
Authors: Manjubala I. , Ponomarev Igor , Wilke Ingo , Jandt Klaus D. 
Published: April 2007

AbstractPorous scaffold materials that can provide a framework for the cells to adhere, proliferate, and create extracellular matrix are considered to be suitable materials for bone regeneration. Interconnected porous chitosan scaffolds were prepared by freeze‐drying method, and were mineralized by calcium and phosphate solution by double‐diffusion method to form nanoapatite in chitosan matrix. The mineralized chitosan scaffold contains hydroxyapatite nanocrystals on the surface and also within the pore channels of the scaffold. To assess the effect of apatite and porosity of the scaffolds on cells, human osteoblast (SaOS‐2) cells were cultured on unmineralized and mineralized chitosan scaffolds. The cell growth on the mineralized scaffolds and on the pure chitosan scaffold shows a similar growth trend. The total protein content and alkaline phosphatase enzyme activity of the cells grown on scaffolds were quantified, and were found to increase over time in mineralized scaffold after 1 and 3 weeks of culture. The electron microscopy of the cell‐seeded scaffolds showed that most of the outer macropores became sealed off by a continuous layer of cells. The cells spanned around the pore wall and formed extra cellular matrix, consisting mainly of collagen in mineralized scaffolds. The hydroxyproline content also confirmed the formation of the collagen matrix by cells in mineralized scaffolds. This study demonstrated that the presence of apatite nanocrystals in chitosan scaffolds does not significantly influence the growth of cells, but does induce the formation of extracellular matrix and therefore has the potential to serve for bone tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Evaluation of novel injectable hydrogels for nucleus pulposus replacement
Authors: Vernengo J. , Fussell G. W. , Smith N. G. , Lowman A. M. 
Published: April 2007

AbstractBranched copolymers composed of poly(N‐isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (PEG) are being investigated as anin situforming replacement for the nucleus pulposus of the intervertebral disc. A family of copolymers was synthesized by varying the molecular weight of the PEG blocks and molar ratio of NIPAAm monomer units to PEG branches. Gel swelling, dissolution, and compressive mechanical properties were characterized over 90 days and stress relaxation behavior over 30 days immersionin vitro. It was found that the NIPAAm to PEG molar ratio did not affect the equilibrium swelling and compressive mechanical properties. However, gel elasticity exhibited a dependency on both the PEG block molecular weight and content. The equilibrium gel water content increased and compressive modulus decreased with increasing PEG block size. While all of the branched copolymers showed significant increases in stress relaxation time constant compared to the homopolymer (p< 0.05), the high PEG content PNIPAAm‐PEG (4600 and 8000 g/mol) exhibited the maximum elasticity. Because of its high water content, requisite stiffness and high elastic response, PNIPAAm‐PEG (4600 g/mol) will be further evaluated as a candidate material for nucleus pulposus replacement. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Mechanical basis for bone retention around dental implants
Authors: Alexander Harold , Ricci John L. , Hrico George J. 
Published: April 2007

AbstractThis study, analytically, through finite element analysis, predicts the minimization of crestal bone stress resulting from implant collar surface treatment. A tapered dental implant design with (LL) and without (control, C) laser microgrooving surface treatment are evaluated. The LL implant has the same tapered body design and thread surface treatment as the C implant, but has a 2‐mm wide collar that has been laser micromachined with 8 and 12 μm grooves in the lower 1.5 mm to enhance tissue attachment. In vivo animal and human studies previously demonstrated decreased crestal bone loss with the LL implant. Axial and side loading with two different collar/bone interfaces (nonbonded and bonded, to simulate the C and LL surfaces, respectively) are considered. For 80 N side load, the maximum crestal bone distortional stress around C is 91.9 MPa, while the maximum crestal bone stress around LL, 22.6 MPa, is significantly lower. Finite element analysis suggests that stress overload may be responsible for the loss of crestal bone. Attaching bone to the collar with LL is predicted to diminish this effect, benefiting crestal bone retention. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Surface patterning: Tool to modulate stem cell differentiation in an adipose system
Authors: Chaubey Aditya , Ross Kevin J. , Leadbetter Ross M. , Burg Karen J. L. 
Published: April 2007

AbstractThere are several issues that need to be better understood before breast tissue‐engineering becomes viable clinically. One of the key issues is the interaction between cells and the microtopography of the implant surface. The aim of this study was to evaluate the efficacy of D1 cells, multipotent mouse bone marrow stromal precursors, in differentiating to fat and to characterize their metabolic activity (lactic acid released and glucose consumed) and lipid production when cultured on patterned poly‐L‐lactide (PLLA) films. It was determined that, with appropriate stimulation, the D1 cells displayed morphological characteristics of adipocytes and produced lipid. The results show that the patterned surfaces did affect the rate of lipid production. Polynomial models were proposed to predict the metabolic activity of the cells over a period of time. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Fabrication of novel calcium phosphate/poly(lactic acid) fiber composites
Authors: Kothapalli Chandrasekhar R. , Shaw Montgomery T. , Olson James R. , Wei Mei 
Published: April 2007

AbstractComposites using high‐modulus polylactic acid (PLA) fibers coated with calcium phosphate (CaP) were prepared using a cyclic precipitation technique. Scanning electron microscopy revealed that small nuclei of CaP formed after the first soaking cycle, while large quantities of CaP particles were observed after the sixth cycle. The amount of CaP deposited on the PLA yarn increased with deposition time in Ca2+ and PO solutions and number of cycles, and decreased with stirring rate during washing cycles. It was observed that around 35 wt % of CaP was deposited on the yarn surface after six cycles of cyclic‐soaking. Based on the results, a heterogeneous nucleation and growth mechanism was proposed for the CaP deposition on the surface of hydrolyzed polyester. Composites comprising the coated fibers in a poly(caprolactone) matrix exhibited flexural moduli within the range of that of the cortical bone. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
The effect of roughness on the tribological behavior of the prosthetic pair UHMWPE/TiN‐coated stainless steel
Authors: Gispert M. P. , Serro A. P. , Colaço R. , Pires E. , Saramago B. 
Published: April 2007

AbstractThe effect of roughness on the tribological behavior of the prosthetic pair ultra high molecular weight polyethylene (UHMWPE)/TiN coated stainless steel was investigated. Standard and polished TiN coated stainless steel pins were tested against either standard or smooth UHMWPE disks. Hanks' Balanced Salt Solution (HBSS) and bovine serum albumin (BSA) solution in HBSS were used as lubricants. Friction and wear were determined using a pin‐on‐disk apparatus and the wear mechanisms were investigated through optical microscopy, scanning electron microscopy, and atomic force microscopy. The results showed that the decrease in the roughness led to a reduction of the friction coefficient and of the wear rate of UHMWPE. However, the most important effect was achieved through the decrease in the roughness of the hard TiN counterface while keeping the standard UHMWPE surface. If BSA was added to HBSS, a strong decrease of both the friction coefficient and the polymeric wear was observed independently of the roughness of both the TiN and the polyethylene surfaces. Abrasive and fatigue wear mechanisms are proposed to interpret the experimental results. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Effect of water storage time and composite cement thickness on fatigue of a glass‐ceramic trilayer system
Authors: Silva Nelson R. F. A. , de Souza Grace M. , Coelho Paulo G. , Stappert Christian F. J. , Clark Elizabeth A. , Rekow Elizabeth D. , Thompson Van P. 
Published: April 2007

AbstractAim. Static Hertzian contact tests of monolayer glass‐ceramics in trilayer configurations (glass‐ceramic/cement/composite) have shown that thick cement layers lower strength. This study sought to test the hypothesis that thick resin cement layers lower mouth motion fatigue reliability for flat glass‐ceramic/cement/composite trilayer systems and that aging in water reduces reliability. Methods. Dicor plates (n ≥ 12 per group) (10 × 10 × 0.8 mm3) were aluminum‐oxide abraded (50 μm), etched (60 s), silanized, and bonded (Rely X ARC) to water aged (30 days) Z100 resin blocks (10 × 10 × 4 mm3). Four groups were prepared: (1) thick cement layer (>100 μm) stored in water for 24–48 h, (2) thick cement layer stored for 60 days, (3) thin cement layer (≤100 μm) stored for 24–48 h, and (4) thin cement layer stored for 60 days. The layered structures were fatigued (2 Hz) utilizing mouth motion loading with a step‐stress acceleration method. A master Weibull distribution was calculated and reliability determined (with 90% confidence intervals) at a given number of cycles and load. Results. The aged group (60 d) with thick cement layer had statistically lower reliability for 20,000 cycles at 150 N peak load (0.11) compared with both nonaged groups (24–48 h) (thin layer = 0.90 and thick layer = 0.82) and aged group with thin cement layer (0.89). Conclusion. Trilayer specimens with thick cement layers exhibited significantly lower reliability under fatigue testing only when stored for 60 days in water. The hypothesis was accepted. These results suggest that diffusion of water into the resin cement and also to the glass‐ceramic interface is delayed in the thick cement specimens at 24–48 h. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Thermoreversible gel–sol behavior of biodegradable PCL‐PEG‐PCL triblock copolymer in aqueous solutions
Authors: Liu Cai Bing , Gong Chang Yang , Huang Mei Juan , Wang Ji Wei , Pan Yi Feng , Zhang Yang De , Li Guo Zheng , Gou Ma Ling , Wang Ke , Tu Ming Jing , Wei Yu Quan , Qian Zhi Yong 
Published: April 2007

AbstractA series of biodegradable PCL‐PEG‐PCL block copolymers were successfully synthesized by ring‐opening polymerization of ε‐caprolactone initiated by poly(ethylene glycol) (PEG), which were characterized by 1H NMR, 13C NMR, and FTIR. Their aqueous solution displayed special gel–sol transition behavior with temperature increasing from 4 to 100°C, when the polymer concentration was above corresponding critical gel concentration (CGC). The gel–sol phase diagram was recorded using test tube inverting method and DSC method, which depended not only on chemical composition of copolymers, but also on heating history of copolymer's aqueous solution. As a result, the gel–sol transition temperature could be adjusted, which might be very useful for its application in biomedical fields such as injectable drug delivery system. And the typical shell‐core structure of PCL‐PEG‐PCL micelles was introduced. The micelle‐packing and partial crystallization might be the key gelation machanism for this gel–sol transition behavior of PCL‐PEG‐PCL aqueous solution. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 84B: 165–175, 2008
The essentiality of PKCα and PKCβI translocation for CD14+monocyte differentiation towards macrophages and dendritic cells, respectively
Authors: Lin Yuan‐Feng , Lee Horng‐Mo , Leu Sy‐Jye , Tsai Yu‐Hui 
Published: April 2007

AbstractHuman peripheral CD14+monocytes have been known to differentiate into monocyte‐derived macrophages (MDMs) or dendritic cells (MoDCs) upon suitable stimulation. However, the key intracellular molecule(s) associated with their differentiation towards specific cell types was(were) not fully understood. This study was designated to determine the association of PKC isoenzymes with the differentiation of CD14+monocytes into MDMs or MoDCs. Purified human peripheral CD14+monocytes were cultured with GM‐CSF, or GM‐CSF plus IL‐4 for 7 days to induce cell differentiation. The phenotypic changes were analyzed by Flow‐Cytometry using various specific antibodies to cell type‐specific surface markers. The immunological functions of these differentiated cells were determined by measuring the amounts of TNF‐α secretion for MDMs, and the capacities of antigen‐capturing and bacterial phagocytosis for MoDCs. The translocations of PKC isoenzymes in these cells from cytosol to plasma membrane were examined by Western Blot analysis and Confocal Microscopic observation. The treatment of CD14+monocytes with either GM‐CSF or PMA elicited PKCα translocation and consequently induced their differentiation into MDMs. The inclusion of PKCα/βI specific inhibitor, Go6976, greatly inhibited the GM‐CSF‐induced PKCα translocation and dose‐dependently reduced the GM‐CSF‐ induced MDM differentiation. On the other hand, the simultaneous pretreatment of CD14+monocytes with Go6976 and PKCβ‐specific inhibitor predominantly suppressed the GM‐CSF/IL‐4‐induced generation of MoDCs. Further study demonstrated that GM‐CSF/IL‐4 selectively induced the translocation of PKCβI, not PKCα or PKCβII, in CD14+monocytes. In conclusion, the cell fate commitment of CD14+monocytes towards MDMs or MoDCs appears to be steered by the selective activation of PKCα or PKCβI, respectively. J. Cell. Biochem. 102: 429–441, 2007. © 2007 Wiley‐Liss, Inc.
The molecular mechanisms of vitamin C on cell cycle regulation in B16F10 murine melanoma
Authors: Hahm Eunsil , Jin Dong‐Hoon , Kang Jae Seung , Kim Young‐In , Hong Seung‐Woo , Lee Seung Koo , Kim Ha Na , Jung Da Jung , Kim Jee Eun , Shin Dong Hoon , Hwang Young Il , Kim Yeong Seok , Hur Dae Young , Yang Yoolhee , Cho Daeho , Lee Myeong‐Sok , Lee Wang Jae 
Published: April 2007

AbstractVitamin C has inconsistent effects on malignant tumor cells, which vary from growth stimulation to apoptosis induction. It is well known that melanoma cells are more susceptible to vitamin C than any other tumor cells, but the precise mechanism remains to be elucidated. In the present study, the proliferation of B16F10 melanoma cells was suppressed by vitamin C, which induced growth arrest in a dose‐dependent manner without cytotoxic effects. Therefore, we investigated the changes in cell cycle distribution of B16F10 melanoma cells by staining DNAs with propidium iodide (PI). The growth inhibition of B16F10 melanoma by vitamin C was associated with an arrest of cell cycle distribution at G1 stage. In addition, the levels of p53‐p21Waf1/Cip1 increased during G1 arrest, which were essential for vitamin C‐induced cell cycle arrest. The increased p21Waf1/Cip1 inhibited CDK2. Moreover, the activity of p53‐p21Waf1/Cip1 pathway was closely related with the activation of checkpoint kinase 2 (Chk2). Inhibitor of the PI3K‐family, LY294002 and the ATM/ATR inhibitor, caffeine, blocked vitamin C‐induced growth arrest in B16F10 melanoma cells. These results suggest that vitamin C might be a potent agent to inhibit proliferative activity of melanoma cells via the regulation of Chk2‐p53‐p21Waf1/Cip1 pathway. J. Cell. Biochem. 102: 1002–1010, 2007. © 2007 Wiley‐Liss, Inc.
Protein kinase Cδ‐mediated CREB activation regulates ghrelin‐induced cyclooxygenase‐2 expression and prostaglandin E2 production in human colonic epithelial cells
Authors: Zhao Dezheng 
Published: April 2007

AbstractGhrelin, a newly identified gastric peptide, is known for its potent activity in growth hormone release and appetite. Our recent study showed that ghrelin could stimulate protein kinase C‐mediated activation of nuclear factor‐κB (NF‐κB) and interleukin‐8 secretion in human colonic epithelial cells transfected with a functional ghrelin receptor. In the present study, the effect of ghrelin stimulation on cyclooxygenese‐2 expression and prostaglandin E2 production was examined. The data indicate that ghrelin significantly increased the levels of cyclooxygenase‐2 (COX‐2) protein as well as its promoter activity, which leaded to profound increase in prostaglandin E2 secretion. In order to examine the involvement of NF‐κB and cAMP responsive element‐binding protein (CREB) in this response, the NF‐κB inhibitory protein IκBα or a dominant negative mutant of CREB was co‐transfected into cells and the data show that transfection of either IκBα or DN‐CREB significantly attenuated ghrelin‐induced COX‐2 expression. Moreover ghrelin stimulated phosphorylation of CREB, which was mediated primarily via protein kinase Cδ activation. Furthermore, inhibition of PKCδ function significantly attenuated ghrelin‐induced COX‐2 expression. In addition, ghrelin stimulates phosphorylation of PKCδ. Together, these results indicate that in addition to NF‐κB, protein kinase Cδ‐mediated CREB activation plays an important role in the cellular responses of ghrelin. J. Cell. Biochem. 102: 1245–1255, 2007. © 2007 Wiley‐Liss, Inc.
Electron affinities of heavier phosphoryl and thiophosphoryl halides APX3 (A = O, S and X = Br, I)
Authors: Zeng T. , Jamshidi Z. , Mori H. , Miyoshi E. , Klobukowski M. 
Published: April 2007

AbstractWe carried out computational studies of OPX3 and SPX3 (X = Br and I) molecules and their corresponding anions using density functional theory, Møller‐Plesset, and CCSD(T) methods with newly developed model core potentials (MCP). Reliabilities of the MCP were demonstrated by comparing experimental and calculated results. We computed the geometric structure, electron affinities, and electrostatic moments using systematic sequences of the dzp‐, tzp‐, and qzp‐quality basis sets. Both C3v and Cs symmetries were assumed to ascertain that minima on the potential energy surface were found. Infrared and Raman frequencies were calculated and compared with available experimental data. Natural population analyses were performed and used to determine distribution of the extra electron in anions. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007