bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and assessment of glutaraldehyde‐crosslinked collagen–chitosan hydrogels for adipose tissue engineering
Authors: Wu Xuemei , Black Lindsay , Santacana‐Laffitte Guido , Patrick, Charles W. 
Published: November 2006

AbstractA portfolio of crosslinked chitosan:collagen blends was prepared, and their microarchitecture and water binding capacity were studied to investigate their application for adipose tissue engineering. Glutaraldehyde (GA) concentration had little effect on scaffold morphology or water binding capacity. However, the processing freezing temperature prior to lyophilization affected both. In vitro cytocompatibility of preadipocytes (PAs) was assessed for a candidate collagen:chitosan blend using two assays. Results confirm the viability of PAs on GA‐crosslinked collagen:chitosan scaffolds. A rat subcutaneous pocket assay was employed to assess PA‐seeded scaffolds in vivo. Animal tests proved that PA‐seeded scaffolds were biocompatible, could induce vascularization, and form adipose tissue. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Influence of silanated filler content on the biodegradation of bisGMA/TEGDMA dental composite resins
Authors: Finer Y. , Santerre J.P. 
Published: November 2006

AbstractIt has been shown that an increase in the content of nonsilanated submicron colloidal silica filler particles within dental composites resulted in the release of more bis‐phenol‐A diglycidyl dimethacrylate (bisGMA)‐derived product, bis‐hydroxy‐propoxyphenyl propane, following incubation with cholesterol esterase (CE). This work further investigates the enzyme‐catalyzed biodegradation of fine composite resin systems, containing silanated micron‐size irregular glass fillers, commonly used in clinical restorations. Model composite resin samples (10 or 60% weight fraction silanated barium glass filler, 1 μm average particle size) based on bisGMA/triethylene glycol dimethacrylate (TEGDMA) were incubated in buffer or buffer with CE (pH = 7.0, 37°C) solutions for 32 days. The incubation solutions were analyzed using high‐performance liquid chromatography, UV spectroscopy, and mass spectrometry. Both groups were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. In contrast with previous findings for nonsilanated submicron filler systems, the higher filler containing composite showed an increase in its stability with time, following exposure to esterase and when compared to the lower filler content material. As well, the 60% filler composite leached less unreacted monomer TEGDMA. Since the model composite resins studied here were identical and only the filler content varied, the differences in biostability could be specifically associated with the relative amount of resin/filler distribution. The clinical use of different materials in varied dental applications (ranging from fissure sealant to tooth‐colored highly filled materials) must consider the potential for different degradation profiles to occur as a function of filler content. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Depth‐dependent mechanical properties of enamel by nanoindentation
Authors: Zhou Jikou , Hsiung Luke L. 
Published: November 2006

AbstractNanoindentation has recently emerged to be the primary method to study the mechanical behavior and reliability of human enamel. Its hardness and elastic modulus were generally reported as average values with standard deviations that were calculated from the results of multiple nanoindentation testing. In such an approach, it is assumed that the mechanical properties of human enamel are constant, independent of testing parameters, like indent depth and loading rate. However, little is known if they affect the measurements. In this study, we investigated the dependence of the hardness and elastic modulus of human enamel on the indent depth. We found that in a depth range from 100 to 2000 nm the elastic moduli continuously decreased from ∼104 to 70 GPa, and the hardnesses decreased from ∼5.7 to 3.6 GPa. We then considered human enamel as a fiber‐reinforced composite, and used the celebrated rule of mixture theory to quantify the upper and lower bounds of the elastic moduli, which were shown to cover the values measured in the current study and previous studies. Accordingly, we attributed the depth dependence of the hardness and modulus to the continuous microstructure evolution induced by the nanoindenter tip. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Vertical bone augmentation with granulated brushite cement set in glycolic acid
Authors: Mariño F. Tamimi , Torres J. , Tresguerres I. , Jerez L. Blanco , Cabarcos E. López 
Published: November 2006

AbstractBrushite cements are a biocompatible materials that are resorbed in vivo. A new cement composed of a mixture of monocalcium phosphate (MCP) and β‐tricalcium phosphate (β‐TCP) that sets using glycolic acid (GA) was synthesized and characterized. After setting, the cement composition, derived from X‐ray diffraction, was 83 wt % brushite and 17 wt % β‐TCP with an average brushite crystal size of about 2.6 ± 1.4 μm. The cement has a diametral tensile strength of 2.9 ± 0.7 MPa. Granules prepared from the set‐cement were used as grafting material in bone defects on rabbit calvaria for evaluating in vivo its bone regeneration capacity. Considerable cement resorption, improvement in the bone mineral density, and bone neoformation was observed after 4 weeks of the granules' implantation. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Frontal bone defect repair with experimental glass‐fiber‐reinforced composite with bioactive glass granule coating
Authors: Tuusa S. M.‐R. , Peltola M. J. , Tirri T. , Lassila L. V. J. , Vallittu P. K. 
Published: November 2006

AbstractObjective: The aim of this preliminary study was to test the bioactive glass‐coated fiber‐reinforced composite (FRC) as a reconstruction material in the treatment of experimental defects in the frontal bone of rabbits. Methods: FRC made of E‐glass fiber and BisGMA‐PMMA resin matrix system was used in the study. Pieces of nonpolymerized FRC were coated with particulate bioactive glass granules S53P4 (BAG), and then the FRC was polymerized and post‐cured by heat in air to reduce the quantity of residual monomers, and to sterilize the material for the animal study. Two round defects (5 mm in diameter) were drilled in the upper bony walls of 12 NZW rabbits' frontal sinuses, and rectangular FRC plates were applied over the defects. In the control group, no FRC plates were used. The bone defect healing process was evaluated on histological sections at 3, 6, and 8 weeks, postoperatively. SEM‐EDX analysis was used to determine reactive layers of bioactive glass granules. Results: The healing progressed from the fibroconnective tissue phase at 3 weeks to lamellar bone formation at 6 and 8 weeks. The difference in new bone formation between the implantation groups and control groups was not statistically significant, although in some animals the effect of the implant on bone healing was clearly positive. A moderate foreign body reaction was seen on the implant surface where BAG granules did not uniformly cover the implant's polymer matrix. Conclusions: This study suggests that the tested FRC implant with bioactive glass coating provides an alternative for bone defect reconstruction. However, more research on this composite material and its biocompatibility is needed. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
A‐part gel—An efficient adhesion prevention barrier
Authors: Weis Christine , Odermatt Erich K. 
Published: November 2006

AbstractTwo different poly(vinyl alcohol)‐based gels (A‐Part Gel) were compared and evaluated as possible adhesion prophylaxis gels. The gels were implanted to act as a physical barrier—and thus to prevent adhesions—in a rabbit sidewall model. The absorption time of any adhesion barrier is a critical parameter, since the wounded tissue needs to be covered during the healing process. Crosslinking by freeze‐thawing helped to prolong the absorption time of the gels. To better understand the in vivo absorption, the gels were investigated in various physical in vitro methods such as decay measurements and experiments performed in a Soxhlet extraction thimble. The in vivo applicability of the gels by surgeons was judged in squeezing force measurements. The ability to cover the wounded area securely was measured with simple spreading experiments. Both gels could be squeezed out of the syringes easily and showed a homogenous spreading behavior. Comparing the two gels, the results of the in vitro absorption experiments were contradictive. Further, in vivo tests with correlations to the proposed in vitro measurements will reveal the correct interpretation. Nevertheless, the results in a pilot rabbit sidewall model were excellent for both A‐Part gels, but only one gel was chosen for extended studies, showing only 20% adhesions when compared with the control group showing 100% strong adhesion formations. These data will be evaluated in other studies, and the use of an A‐Part PVA‐CMC gel for adhesion prevention has to be supported in clinical studies. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Hydrogel‐filled polylactide porous scaffolds for cartilage tissue engineering
Authors: Gong Yihong , He Lijuan , Li Jun , Zhou Qingliang , Ma Zuwei , Gao Changyou , Shen Jiacong 
Published: November 2006

AbstractPolymer porous scaffolds and hydrogels have been separately employed as analogues of the native extra‐cellular matrix (ECM). However, both of these two kinds of materials have their own advantages and shortcomings. In this work, an attempt to combine the advantages of these two kinds of materials is carried out. Poly‐L‐lactide (PLLA) scaffolds with good mechanical properties were prepared by thermally induced phase separation, which were then filled with hydrogel aiming at entrapment of cells within a support of predefined shape. Agar, which has a function to promote chondrogenesis, was selected to entrap chondrocytes, acting as analogues of native ECM. A straight forward merit of this construct is that both mechanical strength and macroscopic shape, and analogous ECM can be simultaneously achieved. The morphology and distribution of the chondrocytes were studied by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The cell growth behaviors were determined by MTT assay and collagen and glycosaminoglycan (GAG) secretion. After culture for 7 and 14 days, the cells in the construct were round and surrounded by the hydrogel. The MTT viability and the cell secretion in the chondrocytes/agar/scaffold construct were also higher than that of the chondrocytes/scaffold construct (control). Gelatin was further introduced into the construct, yielding improved GAG secretion and cytoviability. After implantation in the subcutaneous dorsum of nude mice for 4 weeks, cartilage‐like specimens maintaining their original rectangular shapes were harvested. Histological examination showed that new cartilage was regenerated and a large quantity of collagen and GAG were secreted, while the cells in the control PLLA scaffold turned to be fibroblast‐like with less secretion of extracellular matrices. The method provides a useful pathway of scaffold preparation and cell transplantation, which can achieve suitable mechanical properties and good cell performance simultaneously. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Journey in reverse: TTP from bedside to blood bank to bench
Authors: Moake Joel L. 
Published: November 2006

AbstractThrombotic thrombocytopenic purpura (TTP) is the most extensive and dangerous intravascular platelet clumping disorder. For more than a half‐century after its initial recognition, mortality was near 100% and the etiology totally obscure. Then, in the late 1970s to early 1980s, empiric, but successful, therapy by a few clinician/blood bank partnerships was followed by sudden laboratory insight into pathophysiology. The discussion that follows was prepared in conjunction with the 2006 Francis Morrison, M.D., Memorial Lecture at the 27th Annual Meeting of the American Society for Apheresis. J. Clin. Apheresis. © 2006 Wiley‐Liss, Inc.
What is the function of centrioles?
Authors: Marshall Wallace F. 
Published: November 2006

AbstractThe function of centrioles has been controversial and remains incompletely resolved. This is because centrioles, in and of themselves, do not directly perform any physiological activity. Instead, their role is only to act as a jig or breadboard onto which other functional structures can be built. Centrioles are primarily involved in forming two structures—centrosomes and cilia. Centrioles bias the position of spindle pole formation, but because spindle poles can self‐organize, the function of the centriole in mitosis is not obligatory. Consequently, lack of centrioles does not generally prevent mitosis, although recent experiments suggest acentriolar spindles have reduced fidelity of chromosome segregation. In contrast, centrioles are absolutely required for the assembly of cilia, including primary cilia that act as cellular antennae. Consistent with this requirement, it is now becoming clear that many ciliary diseases, including nephronophthisis, Bardet‐Biedl syndrome, Meckel Syndrome, and Oral‐Facial‐Digital syndrome, are caused by defects in centriole‐associated proteins. J. Cell. Biochem. 100: 916–922, 2007. © 2006 Wiley‐Liss, Inc.
Palladin regulates cell and extracellular matrix interaction through maintaining normal actin cytoskeleton architecture and stabilizing Beta1‐integrin
Authors: Liu Xue‐Song , Luo Hui‐Jun , Yang Hua , Wang Long , Kong Hui , Jin Yue‐E , Wang Fang , Gu Ming‐Min , Chen Zhu , Lu Zhen‐Yu , Wang Zhu‐Gang 
Published: November 2006

AbstractCell and extracellular matrix (ECM) interaction plays an important role in development and normal cellular function. Cell adhesion and cell spreading on ECM are two basic cellular behaviors related to cell‐ECM interaction. Here we show that palladin, a novel actin cytoskeleton‐associated protein, is actively involved in the regulation of cell‐ECM interaction. It was found that palladin‐deficient mouse embryonic fibroblasts (MEFs) display decreased cell adhesion and compromised cell spreading on various ECMs. Disorganized actin cytoskeleton architecture characterized by faint stress fibers, less lamellipodia and focal adhesions can account for the weakened cell‐ECM interaction in palladin−/− MEFs. Furthermore, decreased polymerized filament actin and increased globular actin can be observed in palladin−/− MEFs, strongly suggesting that palladin is essential for the formation or stabilization of polymerized filament actin. Elevated phospho‐cofilin level and proper responses in cofilin phosphorylation to either Rho signal agonist or antagonist in palladin−/− MEFs indicate that disrupted stress fibers in palladin−/− MEFs is not associated with cofilin phosphorylation. More interestingly, the protein level of ECM receptor β1‐integrin is dramatically decreased in MEFs lacking palladin. Down‐regulation of β1‐integrin protein can be restored by proteasome inhibitor MG‐132 treatment. All these data implicate that palladin is essential for cell‐ECM interaction through maintaining normal actin cytoskeleton architecture and stabilizing β1‐integrin protein. J. Cell. Biochem. 100: 1288–1300, 2007. © 2006 Wiley‐Liss, Inc.
The origin of the two‐electron/four‐centers CC bond in π‐TCNE22− dimers: Electrostatic or dispersion?
Authors: García‐Yoldi Iñigo , Mota Fernando , Novoa Juan J. 
Published: November 2006

AbstractThe structure and stability of the π‐TCNE22− dimers in K2TCNE2 aggregates is revisited trying to find if the origin of their two‐electron/four‐centers CC bond are the electrostatic K+‐TCNE− interactions or the dispersion interactions between the anions. The study is done at the HF, B3LYP, CASSCF (2,2), and MCQDPT/CASSCF (2,2) levels using the 6‐31+G(d) basis set. Our results show that the only minima of this aggregate that preserves the π‐TCNE22− structure has the two K+ atoms placed in equatorial positions in between the two TCNE− planes. When the K+ atoms are placed along the D2h axis of the anions the structure is not a minimum. The main energetic component responsible for the stability of these aggregates comes from the cation–anion interactions. However, a proper accounting of the dispersion component (as done in the MCQDPT/CASSCF (2,2) calculations) is needed to make the closed‐shell singlet more stable than the open‐shell singlet. Thus, the bond results from the combination of the electrostatic and dispersion components, being the first the dominant one. The optimum geometry of the closed‐shell singlet is very similar to the experimental one found in crystals. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007
Atom–atom partitioning of total (super)molecular energy: The hidden terms of classical force fields
Authors: Rafat M. , Popelier P. L. A. 
Published: November 2006

AbstractClassical force fields describe the interaction between atoms that are bonded or nonbonded via simple potential energy expressions. Their parameters are often determined by fitting toab initioenergies and electrostatic potentials. A direct quantum chemical guide to constructing a force field would be the atom–atom partitioning of the energy of molecules and van der Waals complexes relevant to the force field. The authors used the theory of quantum chemical topology to partition the energy of five systems [H2, CO, H2O, (H2O)2, and (HF)2] in terms of kinetic, Coulomb, and exchange intra‐atomic and interatomic contributions. The authors monitored the variation of these contributions with changing bond length or angle. Current force fields focus only on interatomic interaction energies and assume that these purely potential energy terms are the only ones that govern structure and dynamics in atomistic simulations. Here the authors highlight the importance of self‐energy terms (kinetic and intra‐atomic Coulomb and exchange). © 2006 Wiley Periodicals, Inc. J Comput Chem 2007
Gilbert N. Lewis and the chemical bond: The electron pair and the octet rule from 1916 to the present day
Authors: Gillespie R. J. , Robinson E. A. 
Published: November 2006

AbstractWe describe the development of Lewis's ideas concerning the chemical bond and in particular the concept of the electron pair bond and the octet rule. We show that the concept of the electron pair bond has endured to the present day and is now understood to be a consequence of the Pauli principle. In contrast the octet rule is now regarded as much less important than was originally generally believed, although Lewis himself knew several exceptions and regarded it as less important than what he called the rule of two (the electron pair). The octet rule was more strongly promoted by Langmuir who is also responsible for the term covalent bond. However, many more exceptions to the octet rules than were known to Lewis are now known and the terms hypervalent and hypovalent used to describe such molecules are no longer particularly useful. Today it is realized that bonding electron pairs in many molecules are not as well localized as Lewis believed, nevertheless resonance structures, i.e., plausible alternative Lewis structures, are still often used to describe such molecules. Moreover electrons are not always found in pairs, as for example in linear molecules, which can, however, be satisfactorily described by Linnett's double quartet theory. The electron density distribution in a molecule can now be analyzed using the ELF and other functions of the electron density to show where electron pairs are most probably to be found in a molecule. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007
Lipid raft‐dependent endocytosis of metallothionein in HepG2 cells
Authors: Hao Qiang , Hong Sung‐Hye , Maret Wolfgang 
Published: November 2006

AbstractHuman hepatocellular carcinoma (HepG2) cells take up metallothionein (MT) by endocytosis. MT co‐localizes with albumin but not with transferrin, indicating uptake via a non‐classical pathway rather than via clathrin‐mediated endocytosis. A lipid raft‐dependent uptake is indicated by pravastatin inhibition of cholesterol synthesis and methyl‐β‐cyclodextrin inhibition of cholesterol translocation to the plasma membrane, reducing MT uptake by 29% and 69%, respectively. Subcellular fractionation after MT uptake reveals significant amounts of MT in vesicular fractions including lysosomes but virtually no MT in the cytosol. Metals bound to MT are released into the cytosol, however. The findings define a pathway for cellular metal acquisition. Together with results from other studies demonstrating secretion of MT from different cells and the presence of MT in extracellular fluids, the results suggest a function of MT in intercellular communication. J. Cell. Physiol. 210: 428–435, 2007. © 2006 Wiley‐Liss, Inc.
The search for non‐chordate retinoic acid signaling: lessons from chordates
Authors: Simões‐costa Marcos S. , Azambuja Ana Paula , Xavier‐Neto José 
Published: November 2006

AbstractSignaling by retinoic acid (RA) is an important pathway in the development and homeostasis of vertebrate and invertebrate chordates, with a critical role in mesoderm patterning. Classical studies on the distribution of nuclear receptors of animals suggested that the family of RA receptors (RARs/NR1B) was restricted to chordates, while the family of RA X receptors (RXR/NR2B) was distributed from cnidarians to chordates. However, the accumulation of data from genome projects and studies in non‐model species is questioning this traditional view. Here we discuss the evidence for non‐chordate RA signaling systems in the light of recent advances in our understanding of carotene (pro‐Vitamin A) metabolism and of the identification of potential RARs and members of the NR1 family in echinoderms and lophotrochozoan trematodes, respectively. We conclude, as have others before (Bertrand et al., 2004. Mol Biol Evol 21(10):1923–1937), that signaling by RA is more likely an ancestral feature of bilaterians than a chordate innovation. J. Exp. Zool. (Mol. Dev. Evol.) 310B:54–72, 2008. © 2006 Wiley‐Liss, Inc.
The minimum degree of Ramsey‐minimal graphs
Authors: Fox Jacob , Lin Kathy 
Published: November 2006

AbstractWe write H → G if every 2‐coloring of the edges of graph H contains a monochromatic copy of graph G. A graph H is G‐minimal if H → G, but for every proper subgraph H′ of H, H′ ↛ G. We define s(G) to be the minimum s such that there exists a G‐minimal graph with a vertex of degree s. We prove that s(Kk) = (k − 1)2 and s(Ka,b) = 2 min(a,b) − 1. We also pose several related open problems. © 2006 Wiley Periodicals, Inc. J Graph Theory 54: 167–177, 2007
Independent dominating sets and hamiltonian cycles
Authors: Haxell Penny , Seamone Ben , Verstraete Jacques 
Published: November 2006

AbstractA graph is uniquely hamiltonian if it contains exactly one hamiltonian cycle. In this note we prove that there are no r‐regular uniquely hamiltonian graphs when r > 22. This improves upon earlier results of Thomassen. © 2006 Wiley Periodicals, Inc. J Graph Theory 54: 233–244, 2007