bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of porous PDLLA/HA composite foams by supercritical carbon dioxide technology
Authors: Teng Xinrong , Ren Jie , Gu Shuying 
Published: August 2006

AbstractA composite poly(D,L)lactic acid (PDLLA)/hydroxyapatite (HA) biomaterial was prepared by in situ polymerization of D,L‐lactide monomer and HA. Supercritical CO2 (SC CO2) technology was developed to prepare the biodegradable composite foams for use in tissue regeneration. In this technology, NaCl particles were used as porogen to produce an open‐pore structure. Organic solvents were not used and high temperature was not necessary. The problem with pore interconnectivity was resolved. High‐porosity composite foams (up to 90% ± 2% porosity) were obtained with pore sizes ranging from 100 to 300 μm suitable for cell seeding. The microstructure and morphology of the composite foams could be controlled by saturation pressure, saturation time, and temperature as well as amount of NaCl particles. The compressive strength and water absorbability of the composite foams were also determined. With an increase in HA amount, the molecular weight of PDLLA/HA composite foams decreased, but the mechanical strength and hydrophilicity increased slightly. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Experimental lumbar spine fusion with novel tantalum‐coated carbon fiber implant
Authors: Li Haisheng , Zou Xuenong , Woo Charlotte , Ding Ming , Lind Martin , Bünger Cody 
Published: August 2006

AbstractImplants of carbon fiber composite have been widely used in orthopedic and spinal surgeries. However, studies using carbon fiber‐reinforced cages demonstrate frequent appearance of fibrous layer interposed between the implant and the surrounding bone. The aim of the present study was to test the possibility of coating a biocompatible metal layer on top of the carbon fiber material, to improve its biological performance. Tantalum was chosen because of its bone compatibility, based on our previous studies. A novel spinal fusion cage was fabricated by applying a thin tantalum coating on the surface of carbon–carbon composite material through chemical vapor deposition. Mechanical and biological performance was tested in vitro and in vivo. Compress strength was found to be 4.9 kN (SD, 0.2). Fatigue test with 500,000 cycles was passed. In vitro radiological evaluation demonstrated good compatibility with X‐ray and CT scan examinations. In vivo test employed eight pigs weighing 50 kg each. Instrumented lumbar spine fusion of L3/4 and L4/5 with these cages was performed on each pig. After 3 months, excellent bone integration property was demonstrated by direct contact of the cage with the host bone and newly formed bone. No inflammatory cells were found around the implant. Cages packed with two different graft materials (autograft and COLLOSS) achieved the same new bone formation. The present study proved that coating tantalum on top of the carbon‐based implant is feasible, and good bone integration could be achieved. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Amniotic membrane immobilized poly(vinyl alcohol) hybrid polymer as an artificial cornea scaffold that supports a stratified and differentiated corneal epithelium
Authors: Uchino Yuichi , Shimmura Shigeto , Miyashita Hideyuki , Taguchi Tetsushi , Kobayashi Hisatoshi , Shimazaki Jun , Tanaka Junzo , Tsubota Kazuo 
Published: August 2006

AbstractPoly(vinyl alcohol) (PVA) is a biocompatible, transparent hydrogel with physical strength that makes it promising as a material for an artificial cornea. In our previous study, type I collagen was immobilized onto PVA (PVA‐COL) as a possible artificial cornea scaffold that can sustain a functional corneal epithelium. The cellular adhesiveness of PVA in vitro was improved by collagen immobilization; however, stable epithelialization was not achieved in vivo. To improve epithelialization in vivo, we created an amniotic membrane (AM)‐immobilized polyvinyl alcohol hydrogel (PVA‐AM) for use as an artificial cornea material. AM was attached to PVA‐COL using a tissue adhesive consisting of collagen and citric acid derivative (CAD) as a crosslinker. Rabbit corneal epithelial cells were air‐lift cultured with 3T3 feeder fibroblasts to form a stratified epithelial layer on PVA‐AM. The rabbit corneal epithelial cells formed 3–5 layers of keratin‐3‐positive epithelium on PVA‐AM. Occludin‐positive cells were observed lining the superficial epithelium, the gap‐junctional protein connexin43‐positive cells was localized to the cell membrane of the basal epithelium, while both collagen IV were observed in the basement membrane. Epithelialization over implanted PVA‐AM was complete within 2 weeks, with little inflammation or opacification of the hydrogel. Corneal epithelialization on PVA‐AM in rabbit corneas improved over PVA‐COL, suggesting the possibility of using PVA‐AM as a biocompatible hybrid material for keratoprosthesis. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Fibroblast cell attachment and growth on nanoengineered sculptured thin films
Authors: Demirel M. C. , So E. , Ritty T. M. , Naidu S. H. , Lakhtakia A. 
Published: August 2006

AbstractNanoengineered parylene‐C sculptured thin films (STFs) are deposited on glass and silicon substrates using a direct one‐step growth technique. The deposited STFs support fibroblast cell attachment and proliferation in vitro, which is an early indication of biocompatibility and bioactivity of this emerging class of biomaterials. Surface modification of endoprostheses of the small joints of the hand, which heal with fibrous stabilization, may be greatly enhanced by such nanoengineered biomaterials. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Influence of initial component temperature on the apparent viscosity and handling characteristics of acrylic (PMMA) bone cement
Authors: Sullivan Stacey J. Losaw , Topoleski L. D. Timmie 
Published: August 2006

AbstractThe flow and polymerization characteristics of poly(methylmethacrylate) (PMMA) bone cement can be changed by manipulating the temperature of the bone cement components or the environment that they are prepared in. To quantify the effects of the initial component temperature (Tic) of acrylic bone cement on the rheological and handling characteristics, ASTM F451‐99a compliant methods and clinically relevant testing methods were utilized. A rheometer was designed and fabricated using the dimensions of a clinical, commercially available, cement gun and nozzle. The influence on the apparent viscosity and handling characteristics (setting time, working time, and peak exotherm temperature) for a high viscosity (HV) commercially‐available acrylic bone cement, Palacos R, were determined. The values of Tic used were 23 °C (room), 6 °C (refrigerator), and −14 °C (freezer). Using the apparent viscosity of a medium viscosity (MV) bone cement as a benchmark (Simplex P at room temperature), it was found that by adjusting the Tic the HV cement was able to mimic the flow characteristics of the MV cement. Lowering the Tic lowered the apparent viscosity of the bone cement. The effects of Tic on the polymerization of bone cement were studied in dynamic and static conditions. The dynamic test recorded temperature and torque from stirring resistance. Setting times were also determined using the ASTM exotherm mold method. The setting times determined by the dynamic testing conditions were consistently shorter than those determined by the ASTM method. Lowering the Tic increased the working and setting times; however, it did not have a significant effect on the peak exotherm temperature. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
PARP‐3 associates with polycomb group bodies and with components of the DNA damage repair machinery
Authors: Rouleau M. , McDonald D. , Gagné P. , Ouellet M.‐E. , Droit A. , Hunter J.M. , Dutertre S. , Prigent C. , Hendzel M.J. , Poirier G.G. 
Published: August 2006

AbstractPoly(ADP‐ribose) polymerase 3 (PARP‐3) is a novel member of the PARP family of enzymes that synthesize poly(ADP‐ribose) on themselves and other acceptor proteins. Very little is known about this PARP, which is closely related to PARP‐1 and PARP‐2. By sequence analysis, we find that PARP‐3 may be expressed in two isoforms which we studied in more detail to gain insight into their possible functions. We find that both PARP‐3 isoforms, transiently expressed as GFP or FLAG fusions, are nuclear. Detection of endogenous PARP‐3 with a specific antibody also shows a widespread nuclear distribution, appearing in numerous small foci and a small number of larger foci. Through co‐localization experiments and immunoprecipitations, the larger nuclear foci were identified as Polycomb group bodies (PcG bodies) and we found that PARP‐3 is part of Polycomb group protein complexes. Furthermore, using a proteomics approach, we determined that both PARP‐3 isoforms are part of complexes comprising DNA‐PKcs, PARP‐1, DNA ligase III, DNA ligase IV, Ku70, and Ku80. Our findings suggest that PARP‐3 is a nuclear protein involved in transcriptional silencing and in the cellular response to DNA damage. J. Cell. Biochem. 100: 385–401, 2007. © 2006 Wiley‐Liss, Inc.
Frequency domain lifetime and spectral imaging microscopy
Authors: Pelet Serge , Previte Michael J.R. , Kim Daekeun , Kim Ki Hean , SU Tsu‐Te J. , So Peter T.C. 
Published: August 2006

AbstractIn the femtoliter observation volume of a two‐photon microscope, multiple fluorophores can be present and complex photophysics can take place. Combined detection of the fluorescence emission spectra and lifetimes can provide deeper insight into specimen properties than these two imaging modalities taken separately. Therefore, we have developed a detection scheme based on a frequency‐modulated multichannel photomultiplier, which measures simultaneously the spectrum and the lifetime of the emitted fluorescence. Experimentally, the efficiency of the frequency domain lifetime measurement was compared to a time domain set‐up. The performance of this spectrally and lifetime‐resolved microscope was evaluated on reference specimens and living cells labeled with three different stains targeting the membrane, the mitochondria, and the nucleus. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
DNA vaccination against foot‐and‐mouth disease via electroporation: study of molecular approaches for enhancing VP1 antigenicity
Authors: Kim Suk‐Am , Liang Chi‐Ming , Cheng Ivan‐Chen , Cheng Yung‐Chih , Chiao Ming‐Tsang , Tseng Chia‐Jen , Lee Fan , Jong Ming‐Hwa , Tao Mi‐Hua , Yang Ning‐Sun , Liang Shu‐Mei 
Published: August 2006

AbstractBackgroundFoot‐and‐mouth disease virus (FMDV) affects susceptible livestock animals and causes disastrous economic impact. Immunization with plasmid expressing VP1 that contains the major antigenic epitope(s) of FMDV as cytoplasmic protein (cVP1) failed to elicit full protection against FMDV challenge.Materials and methodsIn this study, mice were immunized via electroporation with four cDNA expression vectors that were constructed to express VP1 of FMDV, as cytoplasmic (cVP1), secreted (sVP1), membrane‐anchored (mVP1) or capsid precursor protein (P1), respectively, to evaluate whether expression of VP1 in specific subcellular compartment(s) would result in better immune responses.ResultsElectroporation enhanced immune responses to vectors expressing cVP1 or P1 and expedited the immune responses to vectors expressing sVP1 or mVP1. Immunization of mice via electroporation with mVP1 cDNA was better than sVP1 or cVP1 cDNA in eliciting neutralizing antibodies and viral clearance protection. Vaccination with P1 cDNA, nonetheless, yielded the best immune responses and protection among all four cDNAs that we tested.ConclusionsThese results suggest that the antigenicity of a VP1 DNA vaccine can be significantly enhanced by altering the cellular localization of the VP1 antigen. Electroporation is a useful tool for enhancing the immune responses of vectors expressing VP1 or P1. By mimicking FMDV more closely than that of transgenic VP1 and eliciting immune responses favorably toward Th2, transgenic P1 may induce more neutralizing antibodies and better protection against FMDV challenge. Copyright © 2006 John Wiley & Sons, Ltd.
Identification and characterization of homologues of vertebrate β‐thymosin in the marine mollusk Aplysia californica
Authors: Romanova Elena V. , Roth Michael J. , Rubakhin Stanislav S. , Jakubowski Jennifer A. , Kelley Wayne P. , Kirk Mark D. , Kelleher Neil L. , Sweedler Jonathan V. 
Published: August 2006

AbstractThe β‐thymosins have been known as actin‐sequestering proteins, but now are recognized as molecules with multiple and diverse intracellular and extracellular functions. Two closely related proteins, β‐thymosinHis and β‐thymosinGln, have been de novo sequenced by top‐down mass spectrometry in the common neurobiology model, Aplysia californica. As determined by nanoelectrospray quadrupole‐enhanced Fourier‐Transform mass spectrometry with collisionally activated and electron‐capture dissociations, both of these Aplysia β‐thymosins are acetylated and differ by a single residue in the central actin‐binding domain. Profiling of individual cells and tissue by matrix‐assisted laser desorption/ionization mass spectrometry reveals that these proteins are widely expressed in the Aplysia central nervous system, including in individual identified neurons, neuronal clusters, nerves and connective tissues. Newly identified β‐thymosinHis and β‐thymosinGln are also detected by mass spectrometry in hemolymph, and in releasates collected from whole ganglia. When applied exogenously, β‐thymosin proteins, purified from nerve cell extract, support the anchoring of neurons, and increase neurite sprouting and total neurite outgrowth in culture. These positive effects on neurite regeneration in cell culture suggest that the β‐thymosin proteins have an extracellular function in the central nervous system of Aplysia californica. Copyright © 2006 John Wiley & Sons, Ltd.
An unprecedented rearrangement in collision‐induced mass spectrometric fragmentation of protonated benzylamines
Authors: Bialecki Jason , Ruzicka Josef , Attygalle Athula B. 
Published: August 2006

AbstractThe collision‐induced dissociation (CID) mass spectra of several protonated benzylamines are described and mechanistically rationalized. Under collision‐induced decomposition conditions, protonated dibenzylamine, for example, loses ammonia, thereby forming an ion of m/z 181. Deuterium labeling experiments confirmed that the additional proton transferred to the nitrogen atom during this loss of ammonia comes from the ortho positions of the phenyl rings and not from the benzylic methylene groups. A mechanism based on an initial elongation of a CN bond at the charge center that eventually cleaves the CN bond to form an ion/neutral complex of benzyl cation and benzylamine is proposed to rationalize the results. The complex then proceeds to dissociate in several different ways: (1) a direct dissociation to yield a benzyl cation observed at m/z 91; (2) an electrophilic attack by the benzyl cation within the complex on the phenyl ring of the benzylamine to remove a pair of electrons from the aromatic sextet to form an arenium ion, which either donates a ring proton (or deuteron when present) to the amino group forming a protonated amine, which undergoes a charge‐driven heterolytic cleavage to eliminate ammonia (or benzylamine) forming a benzylbenzyl cation observed at m/z 181, or undergoes a charge‐driven heterolytic cleavage to eliminate diphenylmethane and an immonium ion; and (3) a hydride abstraction from a methylene group of the neutral benzylamine to the benzylic cation to eliminate toluene and form a substituted immonium ion. Corresponding benzylamine and dibenzylamine losses observed in the spectra of protonated tribenzylamine and tetrabenzyl ammonium ion, respectively, indicate that the postulated mechanism can be widely applied. The postulated mechanisms enabled proper prediction of mass spectral fragments expected from protonated butenafine, an antifungal drug. Copyright © 2006 John Wiley & Sons, Ltd.
Identification of radiation‐induced cross‐linking between thymine and tryptophan by electrospray ionization‐mass spectrometry
Authors: Shi Wei‐Qun , Hu Jia , Zhao Wei , Su Xiao‐Yang , Cai Hui , Zhao Yu‐Fen , Li Yan‐Mei 
Published: August 2006

AbstractUpon exposure to ionizing radiation, DNA undergoes a variety of modifications including the production of a covalent bond between the nucleobase thymine and aromatic amino acids. In this work, electrospray ionization‐mass spectrometry(ESI‐MS) was used to identify the gamma radiation‐induced covalent cross‐linking of model peptides (sequence YPPW and pYPPW) with the nucleobase thymine. Tandem electrospray ionization‐mass spectrometry (ESI‐MSn) was employed to investigate the cross‐linking sites. The results showed that irrespective of whether tyrosine was phosphorylated or not, the nucleobase thymine was cross‐linked with the tryptophan residue. Possible cross‐linking mechanisms are proposed by investigating the related mass peaks. Copyright © 2006 John Wiley & Sons, Ltd.
Dissociation mechanisms of neutral methyl stearate and its hydrogen atom adduct formed from the respective positive ions by electron transfer
Authors: Hayakawa Shigeo , Kitaguchi Akihiro 
Published: August 2006

AbstractThe mechanism of dissociation of neutral methyl stearate and its hydrogen atom adduct was investigated by charge inversion mass spectrometry using an alkali metal target. Migrations of functional groups in fatty acid ester ions are often observed during the dissociation of the cations in collisionally activated dissociation (CAD). In the charge inversion spectrum, the main dissociation channels of methyl stearate molecule are the loss of a CH3 radical or a H atom. To identify the source of the CH3 radical and the H atom, the charge inversion spectra of partially deuterated methyl stearate (C17H35COOCD3) were measured. The loss of CH3 occurred through elimination from the methoxy methyl group and that of H occurred through elimination from the hydrocarbon chain of the fatty acid group. In the protonated ester, a simultaneous loss of CH3 (from the methoxy methyl group) and a H atom or a H2 molecule was observed. The charge inversion process gave the dissociation fragments with almost no migration of atoms. Only a few peaks that were structure sensitive were observed in the higher mass region in the charge inversion spectra; these peaks were associated with dissociations of energy‐selected neutral species, unlike the case of CAD spectra in which they result from dissociation of ions. Charge inversion mass spectrometry with alkali metal targets provided direct information on the dissociation mechanism of methyl stearate and its hydrogen atom adduct without any migration of functional groups. Copyright © 2006 John Wiley & Sons, Ltd.
DNA analysis by mass spectrometry—past, present and future
Authors: Tost Jörg , Gut Ivo Glynne 
Published: August 2006

AbstractThe analysis of deoxyribose nucleic acid (DNA) by mass spectrometry (MS) has evolved to where it can be used to analyze most known types of DNA and ribose nucleic acid (RNA) situations. It can efficiently deal with the analysis of DNA polymorphisms, sequences, haplotypes, human leukocyte antigen (HLA) typing, DNA methylation and RNA expression. Implementations of MS for these forms of DNA analyses are reviewed. The use of DNA analysis by MS is compared with competing technologies. Finally, an overview is given of worthwhile applications where the know‐how gained so far could be used for future developments. Copyright © 2006 John Wiley & Sons, Ltd.
Molecular epidemiology of hepatitis C virus subtype 3a in injecting drug users
Authors: Morice Yoann , Cantaloube Jean‐François , Beaucourt Stéphanie , Barbotte Laetitia , De Gendt Sija , Goncales Fernando Lopes , Butterworth Lesley , Cooksley Graham , Gish Robert G. , Beaugrand Michel , Fay Fabian , Fay Oscar , Gonzalez Jorge E. , Bringel Martins Regina Maria , Dhumeaux Daniel , Vanderborght Bart , Stuyver Lieven , Sablon Erwin , de Lamballerie Xavier , Pawlotsky Jean‐Michel 
Published: August 2006

AbstractHepatitis C virus subtype 3a (HCV‐3a) originates from Asia and has spread widely among injecting drug users as well as other patient groups in industrialized countries. HCV subtype 3a infection remains highly prevalent and frequently transmitted in the population of intravenous drug users. The objective of this study was to understand better the mechanisms of the worldwide HCV‐3a epidemics in drug users. Ninety‐three sera from HCV‐3a‐infected IDUs from France, the United States, Brazil, Argentina, and Australia were studied. Phylogenetic analyses of the non‐structural 5B region showed no specific clustering according to the continent of the patient's origin. Non‐exclusive clusters of viral sequences from South America, Australia, and California were observed, but topologies were not supported by strong bootstrap values. The results suggest that HCV‐3a has been transmitted from a common origin through a unique worldwide epidemic that rapidly spread among drug users. Regional transmission occurred in the recent past, leading to an embryonic genetic diversification of HCV‐3a among local injecting drug user population. J. Med. Virol. 78:1296–1303, 2006. © 2006 Wiley‐Liss, Inc.
Decreased prevalence of mixed cryoglobulinemia in the HAART era among HIV‐positive, HCV‐negative patients
Authors: Kosmas Nikolaos , Kontos Athanasios , Panayiotakopoulos George , Dimitrakopoulos Antonios , Kordossis Theodore 
Published: August 2006

AbstractThere is an established association between human immunodeficiency virus (HIV) infection and mixed cryoglobulinemia, as demonstrated in studies mostly conducted before the introduction of highly active antiretroviral therapy (HAART). To assess the impact of the latter on the cryoglobulinemic status in patients with HIV infection, 133 consecutive, unselected HIV‐positive patients, from which only 8 (6%) had co‐infection with hepatitis C virus (HCV), were evaluated for the presence of cryoglobulins, according to whether they received or not antiretroviral therapy (ART). Patients shown to be cryoglobulin‐positive in a previous study were assessed prospectively, after introducing HAART. Cryoglobulinemia was found in 10 (7.5%) of 133 patients:4 (3.9%) of 101 patients receiving ART versus 6 (18.8%) of 32 patients not receiving ART (P = 0.013). When HCV‐positive patients were excluded from the analysis, the correlation between cryoglobulinemia and ART remained significant (P = 0.019). Among 11 previously detected cryoglobulin‐positive patients, 8 became cryoglobulin‐negative after receiving HAART for a mean period of 6.5 years (P = 0.039). Thus, ART seems to decrease the prevalence of cryoglobulinemia in HIV‐infected, HCV‐negative patients, a finding which provides indirect evidence of the etiologic role of HIV in the pathogenesis of cryoglobulins. J. Med. Virol. 78:1257–1261, 2006. © 2006 Wiley‐Liss, Inc.