bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and in vitro characterization of novel bioactive glass ceramic nanoparticles
Authors: Hong Zhongkui , Reis Rui L. , Mano João F. 
Published: February 2008

AbstractSiO2‐CaO‐P2O5 ternary bioactive glass ceramic (BGC) nanoparticles with different compositions were prepared via a three‐step sol‐gel method. Polyethylene glycol was selected to be used as the surfactant to improve the dispersion of the nanoparticles. The morphology and composition of these BGC nanoparticles were observed by ESEM and EDX. All the BGC particles obtained in this method were about 20 nm in diameter. XRD analysis demonstrated that the different compositions can result in very different crystallinities for the BGC nanoparticles. Bioactivity tests in simulated body fluid solution (SBF), and degradability in phosphate buffer solution (PBS), were performed in vitro. SEM, EDX, and XRD were employed to monitor the surface variation of neat poly(L‐lactic acid), PLLA, foam and PLLA/BGC porous scaffolds during incubation. The BGC nanoparticles with lower phosphorous and relative higher silicon content exhibited enhanced mineralization capability in SBF and a higher solubility in PBS medium. Such novel nanoparticles may have potential to be used in different biomedical applications, including tissue engineering or the orthopedic field. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Activation of human leukocytes on tantalum trabecular metal in comparison to commonly used orthopedic metal implant materials
Authors: Schildhauer T. A. , Peter E. , Muhr G. , Köller M. 
Published: February 2008

AbstractWe analyzed leukocyte functions and cytokine response of human leukocytes toward porous tantalum foam biomaterial (Trabecular Metal™, TM) in comparison to equally sized solid orthopedic metal implant materials (pure titanium, titanium alloy, stainless steel, pure tantalum, and tantalum coated stainless steel). Isolated peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) were cocultured with equally sized metallic test discs for 24 h. Supernatants were analyzed for cytokine content by enzyme‐linked immunosorbent assay. Compared to the other used test materials there was a significant increase in the release of IL (interleukin)‐1ra and IL‐8 from PMN, and of IL‐1ra, IL‐6, and TNF‐α from PBMC in response to the TM material. The cytokine release correlated with surface roughness of the materials. In contrast, the release of IL‐2 was not induced showing that mainly myeloid leukocytes were activated. In addition, supernatants of these leukocyte/material interaction (conditioned media, CM) were subjected to whole blood cell function assays (phagocytosis, chemotaxis, bacterial killing). There was a significant increase in the phagocytotic capacity of leukocytes in the presence of TM‐conditioned media. The chemotactic response of leukocytes toward TM‐conditioned media was significantly higher compared to CM obtained from other test materials. Furthermore, the bactericidal capacity of whole blood was enhanced in the presence of TM‐conditioned media. These results indicate that leukocyte activation at the surface of TM material induces a microenvironment, which may enhance local host defense mechanisms. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Synthesis, self‐assembly in water, and cytotoxicity of MPEG‐block‐PLLA/DX conjugates
Authors: Xie Zhigang , Lu Tiancheng , Chen Xuesi , Zheng Yonghui , Jing Xiabin 
Published: February 2008

AbstractDocetaxel (DX) is one of the most effective antineoplastic drugs. Its current clinical administration is limited because of its hydrophobicity and serious side effects. A polymer/DX conjugate is designed and successfully prepared to solve these problems. It is monomethoxy‐poly(ethylene glycol)‐block‐poly(L‐lactide)/DX (MPEG‐PLLA/DX). It was synthesized by reacting DX with carboxyl‐terminated copolymer MPEG‐PLLA, which was prepared by reacting succinic anhydride with hydroxyl‐terminated copolymer monomethoxy‐poly(ethylene glycol)‐block‐poly(L‐lactide) (MPEG‐PLLA). Its structure and molecular weight was confirmed by 1H NMR and GPC. The MPEG‐PLLA/DX micelles in aqueous solution were prepared using a solvent displacement method and characterized by dynamic light scattering for size and size distribution, and by transmission electron microscopy for surface morphology. Its antitumor activity against HeLa cancer cells evaluated by MTT assay showed that it had a similar antitumor activity to pure DX at the same drug content. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
New class of anti‐microbial agents: Synthesis, characterization, and anti‐microbial activities of metal chelated polyurea
Authors: Ahamad Tansir , Kumar Vikrant , Nishat Nahid 
Published: February 2008

AbstractA new class of metal chelated polyurea have been synthesized by the reaction of toluene 2,4‐diisocyanate (TDI) with chelated Schiff base diamines. The synthesized polyurea have been characterized by analytical, spectral, and thermal analysis. The results of TGA ascribed that [Cu(II)‐PoUA] show better heat resistant properties than other metals chelated polyurea. The antibacterial activities of all the synthesized polymers were determined using the shaking flask method, where 30 mg/mL concentrations of each compound were tested against 105 CFU/mL solutions of S. aureus, E. coli, B. subtillis, S. typhi. The number of viable bacteria was calculated by using the spread plate method on agar plates and the number of viable bacteria was counted after 24 h of incubation period at 37°C. All the polymers showed good antibacterial activity. The Cu(II) chelated polyurea show higher zone of inhibition then other due to higher stability constant and may be used in biomedical applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Boronate‐containing polymer brushes: Characterization, interaction with saccharides and mammalian cancer cells
Authors: Ivanov Alexander E. , Eccles John , Panahi Homayon Ahmad , Kumar Ashok , Kuzimenkova Marina V. , Nilsson Lars , Bergenståhl Björn , Long Nick , Phillips Gary J. , Mikhalovsky Sergey V. , Galaev Igor Yu , Mattiasson Bo 
Published: February 2008

AbstractBoronate‐containing polymer brushes were synthesized by free radical copolymerization of N,N‐dimethylacrylamide (DMAA) and N‐acryloyl‐m‐phenylboronic acid (NAAPBA) (9:1) on the surface of 3‐mercaptopropyl‐silylated glass plates and capillaries. The brushes were characterized with time‐of‐flight secondary ion mass‐spectrometry (ToF SIMS), atomic force microscopy and contact angle measurements. Fructose caused a well‐expressed drop spreading on the surface of copolymer‐grafted glass, due to the strong interaction with the boronate groups. Sedimentation of murine hybridoma cells M2139 or human myeloid leukemia cells KG1 onto the DMAA‐NAAPBA copolymer‐grafted glass plates from 10 mM phosphate buffer solution (pH 8.0) resulted in the cell adhesion. The adhered M2139 and KG1 cells could be quantitatively detached from the grafted plates with 0.1M fructose, which competed with cell surface carbohydrates for binding to the boronates. Evaluation of the binding strength between M2139 cells and the copolymer brush was performed by exposure of the adhered cells to a shear stress. Detachment of a fraction of 18% of the adhered M2139 cells was obtained at a shear force of 1400–2800 pN/cell generated by the running phosphate buffer (pH 8.0), whereas the remaining adhered cells (70%) could be detached with 0.1M fructose dissolved in the same buffer. Possible applications of the boronate‐containing polymer brushes to affinity cell separation can be based upon the facile recovery of the attached cells. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Enhancement of the biological activity of BMP‐2 by synthetic dextran derivatives
Authors: Degat Marie‐Christelle , Dubreucq Guy , Meunier Alain , Dahri‐Correia Latifa , Sedel Laurent , Petite Herve , Logeart‐Avramoglou Delphine 
Published: February 2008

AbstractIn the present study, we explored the binding capacity of synthetic heparin‐like dextran derivatives to recombinant human bone morphogenetic protein 2 (BMP‐2), a heparin‐binding osteoinductive growth factor. Affinity electrophoresis analysis provided evidence that carboxymethylated dextran polymers grafted with high amounts of benzylamide groups (named DMCB) interact with BMP‐2. The capability of such polysaccharides to potentiate the growth factor biological activity was then investigated. In vitro, DMCB dose‐dependently promoted osteoblast differentiation induced by BMP‐2 in C2C12 myoblasts more efficiently than heparin. A screening study provided evidence that the potentiating effects of the dextran derivatives on the BMP‐2‐induced alkaline phosphatase activity improved with their benzylamide groups content and, therefore, with their affinity for the growth factor. The biological activity of BMP‐2 was monitored in the culture medium after 6 days using C2C12 cells (containing a BMP sensitive luciferase reporter gene). Like heparin, DMCB sustained the biological activity of the growth factor; this result suggests that the formation of the BMP‐2/DMCB complex may protect the protein from being inactivated. In rats in vivo, DMCB also stimulated ectopic calcification mediated by BMP‐2. These data indicate that dextran‐based polysaccharides prolong the half‐life of the growth factor and promote its biological activity. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Endothelial cell migration in human plasma is enhanced by a narrow range of added sphingosine 1‐phosphate: Implications for biomaterials design
Authors: Alford Shannon K. , Kaneda Megan M. , Wacker Bradley K. , Elbert Donald L. 
Published: February 2008

AbstractSphingosine 1‐phosphate (S1P) promotes endothelial cell migration in vitro and may potentially impact the endothelialization of implanted biomaterials. However, the effects of S1P on endothelial cells (EC) in flowing blood could be negligible due to preactivation of signaling cascades. We previously developed biomaterials that release S1P and wished to determine through in vitro experiments the extent to which EC respond to S1P added to human platelet poor plasma. We found that addition of 200 nM S1P to platelet poor plasma significantly increased cell migration in two migration models. A lower concentration of S1P added to plasma (100 nM) did not increase endothelial cell migration rates, while the cell migration response was saturated above 200 nM S1P. Expression of the main S1P receptor in EC, S1P1, was elevated in plasma compared to low serum medium, but addition of VEGF or fluid flow elicited a further increase in S1P1 mRNA, consistent with the synergistic effects observed between S1P, VEGF, and fluid flow. Thus, sustained delivery of S1P from biomaterials might only enhance endothelial cell migration if the concentration of S1P at the surface of the material stimulated adjacent EC to the same extent as ≈200 nM S1P added to plasma. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Assembly of multilayer PSS/PAH membrane on coherent alginate/PLO microcapsule for long‐term graft transplantation
Authors: Leung Andy , Trau Matt , Nielsen Lars Keld 
Published: February 2008

AbstractConventional alginate/poly‐L‐ornithine (AP) membranes used to immunoisolate foreign tissue transplants fail in long‐term transplantations of immortal cell lines. We have developed a novel layer‐by‐layer (LbL) membrane using polystyrene sulfonate and polyallylamine hydrochloride (PSS/PAH) on top of the coherent AP membrane. Assembly of the LbL membrane was followed by electrophoresis, and the surface morphologies and structure were characterized and examined by cryo‐scanning electron microscope and transmission electron microscopy. Unlike the standard AP membrane, the LbL membrane withstood the internal pressure generated by continuous cell proliferation of microencapsulated HEK‐293 and Min‐6 cells. The new membrane did not affect insulin secretion or diffusion by Min‐6 cells. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
A biomechanical and histological analysis of standard versus hydroxyapatite‐coated pins for external fixation
Authors: Moroni Antonio , Cadossi Matteo , Romagnoli Matteo , Faldini Cesare , Giannini Sandro 
Published: February 2008

AbstractThis sheep study was designed to make a comparative evaluation of two external fixation pin types each with and without hydroxyapatite (HA) coating. The two pins had different taper, pitch, and self drilling capabilities. Twenty Orthofix standard, self‐tapping pins (group A), 20 Orthofix HA‐coated, self‐tapping pins (group B), 20 X‐caliber, self‐drilling, self‐tapping pins (group C), and 20 X‐caliber HA‐coated, self‐drilling, self‐tapping pins (group D) were selected. Four pins were implanted in the right femurs of 20 adult sheep that were euthanized at 6 weeks. Mean pin insertion torque was 2745 ± 822 Nmm in group A, 2726 ± 784 Nmm in group B, 2818 ± 552 Nmm in group C, and 2657 ± 732 Nmm in group D (ns). Mean pin extraction torque was 1567 ± 541 Nmm in group A, 2524 ± 838 Nmm in group B, 1650 ± 650 Nmm in group C, and 2517 ± 726 Nmm in group D. HA‐coated pins (group B and D) had a significantly greater mean pin extraction torque compared to similar uncoated pins (group A and C) (p < 0.0005). Histological analysis showed good osteointegration of the two coated pin types. This study shows that HA‐coating is more important for optimal pin fixation than the particular combination of design parameters used in each pin type. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Inhibition of mineralization by a calcium zirconium phosphate coating
Authors: Bernstein Anke , Nöbel Doreen , Mayr Hermann O. , Göbel Felix , Berger Georg , Ploska Ute , Gildenhaar Renate , Brandt Jörg 
Published: February 2008

AbstractBioactive ceramics used as coating materials combine the conductive properties of a bioceramic with the mechanical stability of the metal implant. We studied a calcium zirconium phosphate‐containing coating material, FA‐CZP [Ca5(PO4)3F, CaZr4(PO4)6], that is relatively insoluble in the biological milieu. The reaction of bone to this material was investigated histologically and histomorphometrically in an animal trial. Cylindrical Ti6Al4V specimens that had been coated with FA‐CZP by plasma spraying were implanted in the femoral condyles of rabbits. The implants were left in place for 2, 4, 6, 12, and 14 weeks. FA‐CZP led to impaired mineralization of the newly formed bone at the interface. Noncalcified osteoid was found throughout the whole study period. The layer seemed to become thicker with time. The mineralization disorder is evidently caused by zirconium ions. The presence of zirconium in the osteoid in contact with the implant was demonstrated by means of two different staining methods. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Thin films of oriented collagen fibrils for cell motility studies
Authors: Amyot Franck , Small Alex , Boukari Hacène , Sackett Dan , Elliott John , McDaniel Dennis , Plant Anne , Gandjbakhche Amir 
Published: February 2008

AbstractCollagen films with oriented fibrils mimic tissues that have been remodeled by fibroblasts, which naturally tend to orient collagen fibrils in vivo. We have prepared thin films of ordered fibrils of collagen I, a major component of the extracellular matrix. The films were prepared by modifying a technique previously used to produce collagen I films for studies of cell morphology and intracellular signaling. By modifying the drying step, we were able to produce thin monolayers of collagen fibrils with consistent orientations over macroscopic (>100 μm) distances. We quantified the degree of orientation of the collagen fibrils using Fourier analysis of optical microscopy images. We also conducted experiments with vascular endothelial cells, and found that cell orientation and migration are well‐correlated with fibril orientation. Using polarized cells, we showed oriented thin collagen film induces natural migration along the fibrils without using any sort of attractor. Taken together, these results demonstrate additional functionality and physiological relevance for a class of films being successfully applied in a variety of cell biology experiments. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Bone formation and resorption in patients after implantation of β‐tricalcium phosphate blocks with 60% and 75% porosity in opening‐wedge high tibial osteotomy
Authors: Tanaka Takaaki , Kumagae Yoshio , Saito Mitsuru , Chazono Masaaki , Komaki Hirokazu , Kikuchi Takahiro , Kitasato Seiichiro , Marumo Keishi 
Published: February 2008

AbstractMost of the implanted porous β‐tricalcium phosphate (β‐TCP) can be resorbed. However, β‐TCP block with 75% porosity is inadequate for weight‐bearing sites until bone incorporation occurs. Thus, the authors have recently developed β‐TCP block with 60% porosity, which is approximately sevenfold greater in terms of compressive strength than that of β‐TCP with 75% porosity. The authors investigated bone formation and resorption of β‐TCP after implantation in patients of β‐TCP blocks with two different porosities. From May 2003 to November 2004, medial opening high tibial osteotomy was performed in 25 patients with a mean age of 66 years. The opened defect was fixed with a Puddu plate. Then 6–8 cm3 of β‐TCP block with 75% porosity was used to fill the cancellous bone defect, except on the medial side where 2.83–3.18 cm3 of wedge‐shaped β‐TCP block with 60% porosity was implanted. At least 2 years after surgery, the 25 patients had no correction loss, and bone formation was noted in all cases. Complete or nearly complete resorption of β‐TCP with 60 and 75% porosity was obtained within 3.5 years. Thirteen biopsy samples obtained from the 60% porosity implantation sites showed good lamellar bone formation, and the percentage of β‐TCP remaining relative to the newly formed bone plus β‐TCP ranged from 0.3 to 14.5%, with a mean of 6.7%. The authors suspect that mechanical stress loading to the medial side of the tibia facilitated bone formation and resorption of β‐TCP with 60% porosity. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Exclusive use of acid citrate dextrose for anticoagulation during extracorporeal photopheresis in patients with contraindications to heparin: An effective protocol
Authors: Nedelcu Elena , Ziman Alyssa , Fernando Leonor P. , Cook Kris , Bumerts Pam , Schiller Gary 
Published: February 2008

AbstractExtracorporeal photopheresis (ECP) routinely uses heparin for anticoagulation. For patients with contraindications to heparin, alternative anticoagulation using acid citrate dextrose (ACD‐A) has been reported to be safe and effective. However, detailed ECP protocols that exclusively use ACD‐A anticoagulation and minimize citrate toxicity have not yet been published. We report a protocol that completely replaces heparin with ACD‐A for ECP, which was developed at the University of California, Los Angeles (UCLA), and our experience since its implementation. ECP was performed with the UVAR XTS photopheresis system using ACD‐A and control of the rate of citrate infusion. Calcium gluconate solution was administered prophylactically and as needed for symptoms of citrate toxicity. The medical records of patients who underwent ECP using the ACD‐A protocol between January 2003 and July 2006 were reviewed. The incidence and severity of citrate toxicity and the technical data for all procedures were analyzed. During this period, 94 ECP procedures were performed with ACD‐A anticoagulation on five patients. All patients tolerated the procedures well without significant complications. Only minimal symptoms of citrate toxicity (grade 1) were observed in 24.5% of all procedures; symptoms resolved promptly following administration of additional calcium gluconate. In conclusion, an effective protocol for ECP using ACD‐A anticoagulation exclusively in patients with contraindications to heparin employs continuous monitoring of flow rates and prophylactic administration of calcium gluconate to minimize citrate toxicity. J. Clin. Apheresis, 2008. Published 2008 Wiley‐Liss, Inc.
Inhibition of Cdc7/Dbf4 kinase activity affects specific phosphorylation sites on MCM2 in cancer cells
Authors: Charych Deborah H. , Coyne Mazie , Yabannavar Asha , Narberes Jamie , Chow Sylvia , Wallroth Marco , Shafer Cynthia , Walter Annette O. 
Published: February 2008

AbstractThe Cdc7/Dbf4 kinase is required for initiation of DNA replication and also plays a role in checkpoint function in response to replication stress. Exactly how Cdc7/Dbf4 mediates those activities remains to be elucidated. Cdc7/Dbf4 physically interacts with and phosphorylates the minichromosome maintenance complex (MCM), such as MCM2, MCM4 and MCM6. Cdc7/Dbf4 activity is required for association of Cdc45 followed by recruitment of DNA polymerase on the chromatin. Using high resolution mass spectrometry, we identified six phosphorylation sites on MCM2, two of them have not been described before. We provide evidence that Cdc7/Dbf4 mediates phosphorylation on serine 108 and serine 40 on human MCM2 in vitro and in vivo in cancer cells in the absence of DNA damage. Antibodies specific to pS108 or pS40 confirmed the sites and established useful read‐outs for inhibition of Cdc7/Dbf4. This report demonstrates the utility of an in vitro to in vivo workflow utilizing immunoprecipitation and mass spectrometry to map phosphorylation sites on endogenous kinase substrates. The approach can be readily generalized to identify target modulation read‐outs for other potential kinase cancer targets. J. Cell. Biochem. 104: 1075–1086, 2008. © 2008 Wiley‐Liss, Inc.
MAPRes: An efficient method to analyze protein sequence around post‐translational modification sites
Authors: Ahmad Ishtiaq , Hoessli Daniel C. , Qazi Wajahat M. , Khurshid Ahmed , Mehmood Abid , Walker‐Nasir Evelyne , Ahmad Munir , Shakoori Abdul R. , Nasir‐ud‐Din  
Published: February 2008

AbstractFunctional switches are often regulated by dynamic protein modifications. Assessing protein functions, in vivo, and their functional switches remains still a great challenge in this age of development. An alternative methodology based on in silico procedures may facilitate assessing the multifunctionality of proteins and, in addition, allow predicting functions of those proteins that exhibit their functionality through transitory modifications. Extensive research is ongoing to predict the sequence of protein modification sites and analyze their dynamic nature. This study reports the analysis performed on phosphorylation, Phospho.ELM (version 3.0) and glycosylation, OGlycBase (version 6.0) data for mining association patterns utilizing a newly developed algorithm, MAPRes. This method, MAPRes (Mining Association Patterns among preferred amino acid residues in the vicinity of amino acids targeted for post‐translational modifications), is based on mining association among significantly preferred amino acids of neighboring sequence environment and modification sites themselves. Association patterns arrived at by association pattern/rule mining were in significant conformity with the results of different approaches. However, attempts to analyze substrate sequence environment of phosphorylation sites catalyzed for Tyr kinases and the sequence data for O‐GlcNAc modification were not successful, due to the limited data available. Using the MAPRes algorithm for developing an association among PTM site with its vicinal amino acids is a valid method with many potential uses: this is indeed the first method ever to apply the association pattern mining technique to protein post‐translational modification data. J. Cell. Biochem. 104: 1220–1231, 2008. © 2008 Wiley‐Liss, Inc.