bluuebunny/crossref_metadata_2025 huggingface dataset:
First Total Synthesis of the Bioactive Anthraquinone Kwanzoquinone C and Related Natural Products by a Diels–Alder Approach
Authors: Tietze Lutz F. , Gericke Kersten M. , Güntner Carlos
Published: August 2006

The first total synthesis of the novel anticancer agent kwanzoquinone C (1), an anthraquinone glycoside which has been isolated from extracts of the roots of orange daylilies(Kaempfer) (Hemerocallis fulva) is reported. The strategy involves the preparation of the tetrasubstituted 1,3‐butadiene 6 by an electrocyclic conrotatory ring opening of the cyclobutanone rac‐11, which is obtained by a [2+2] cycloaddition.Diels–Alder reaction of 6 with the juglone derivative 5 gives the bis‐benzyl‐protected anthraquinone 4 after aromatization. Finally, glycosidation of the phenolic hydroxy group using 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranosyl trichloroacetimidate followed by the cleavage of the benzyl ethers and the solvolysis of the acetate groups yields the natural product 1. A related anthraquinone natural product 2 with antioxidative properties was obtained by using the 1,3‐butadiene 17 and the juglone derivative 16 as substrates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
The HR competencies‐HR effectiveness link: A study in Taiwanese high‐tech companies
Authors: Han Jian , Chou Paul , Chao Minston , Wright Patrick M.
Published: August 2006

This article explores the relationship between HR competencies and HR effectiveness as perceived by line managers and employees within 39 surveyed Taiwanese high‐tech firms. The data were collected from multiple constituencies in the form of four targeted surveys, and the analysis was conducted at the firm level. Respondents included 182 high‐level executives, 152 HR managers, 320 line managers, and 1,262 employees. Results suggest that in the Taiwanese high‐tech context, HR competencies of field expertise and change management are strongly related to HR effectiveness as perceived by line managers and employees, while business knowledge is not. Managerial implications and future research direction are also discussed in the article. This study contributes to a better understanding of HRM competencies and HR effectiveness within an international context. © 2006 Wiley Periodicals, Inc.
A competence‐based and multidimensional operationalization and measurement of employability
Authors: Heijde Claudia M. Van Der , Van Der Heijden Beatrice I. J. M.
Published: August 2006

Employability is a critical requirement for enabling both sustained competitive advantage at the firm level and career success at the individual level. We propose a competence‐based approach to employability derived from an expansion of the resource‐based view of the firm. In this contribution, we present a reliable and valid instrument for measuring employability. This measure is based on a five‐dimensional conceptualization of employability, in which occupational expertise is complemented with generic competences. Two sources of raters (employees and their immediate supervisors) are involved in developing and testing the measure. Since the five dimensions of employability explain a significant amount of variance in both objective and subjective career success, the predictive validity of the tool is promising. This instrument facilitates further scientific HRM research and is of practical value in light of job and career assessments, recruitment, staffing, career mobility, and development practices. © 2006 Wiley Periodicals, Inc.
The development of strategic human resource professionals at bae systems
Authors: Quinn Ryan W. , Brockbank Wayne
Published: August 2006

Dynamic trends in the external business environment, in the challenges that companies face, and in the nature of HR itself demand that HR departments develop new capabilities and that HR professionals develop new competencies. This article examines BAE Systems (U.K.) as a detailed case study of a company that understands the demand for greater HR contribution to business value. BAE Systems acted on that understanding by providing a comprehensive HR professional development program to enhance the competencies of its HR professionals in order to encourage better business performance. Pre‐ and postprogram measures and extensive qualitative interviews about HR's impact on business performance evidences the effectiveness of this comprehensive approach to the development of HR professional competencies. © 2006 Wiley Periodicals, Inc.
Book review
Authors: Johnson Diane E.
Published: August 2006

Roland E. Kidwell Jr. & Christopher L. Martin (Eds.). (2005). Managing Organizational Deviance. Thousand Oaks, CA: Sage. 376 pages.
Phase evaluation of an effervescent‐added apatitic calcium phosphate bone cement
Authors: Hesaraki Saeed , Moztarzadeh Fatollah , Solati‐Hashjin Mehran
Published: August 2006

Development of macroporosity during setting would allow fast bone ingrowth and good osteointegration of the implant. The interconnected macropores could be created in calcium phosphate cements (CPCs) through the addition of an effervescent porogen mixture to the component of the cements. But this addition could also affect other characteristics of CPCs, such as setting time, mechanical strength, extent of conversion of reactant to apatite phase, crystallinity, and chemical composition of apatite lattice. In this study, these properties were investigated in an effervescent‐added calcium phosphate bone cement. From 0 to 20 wt % of an effervescent mixture was added to calcium phosphate cement (CPC) components and phase evaluations were performed after 24 h incubation at 37°C and 28% relative humidity and 1, 3, 7, and 14 days immersion in a specific simulated body fluid. XRD and FTIR techniques were used to characterize the cement composition, crystallinity, and chemical groups in final CPCs. The results showed that addition of effervescent porogen affects the extent of conversion of reactant to apatite phase and crystallinity. In other words, using the effervescent porogen in CPCs could accelerate the rate of conversion of TTCP/DCPA reactant to apatite phase with smaller crystallites, so that it was the predominant phase (about 67%) after only 3 days soaking in SBF solution. The content of carbonate groups substituted for phosphate groups in apatite lattice increased when the effervescent additive was further added. The compressive strength of the set calcium phosphate cement decreased significantly with the addition of the effervescent agent and reached from 8 MPa for additive‐free CPC to 1.3 MPa for 20% effervescent‐added CPC. The compressive strength was improved after 3 days immersing of CPC in the simulated body fluid solution. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Changes in color and color parameters of dental resin composites after polymerization
Authors: Kim Il‐Jang , Lee Yong‐Keun
Published: August 2006

Objectives.

The objectives were to measure the color change of varied shades of dental resin composites after polymerization, and to determine the correlation among the polymerization color change and the changes in color parameters after polymerization.

Methods.

Eight light‐curing resin composites, a total of 41 shades, were studied. Color of specimens (1 mm in thickness) was measured on a reflection spectrophotometer before and after polymerization over a white background. Changes in color (ΔE*ab), and color parameters (ΔL*, ΔC*ab, Δa*, and Δb*: value after polymerization – value before polymerization) were calculated.

Results.

The range of changes in each shade of resin composites was 1.1–7.9 for color (ΔE*ab), −7.5 to 2.3 for ΔL*, −6.8 to 3.1 for ΔC*ab, −0.9 to 1.2 for Δa*, and −6.8 to 3.1 for Δb*. ΔE*ab, ΔL*, ΔC*ab, Δa*, and Δb* were influenced by the brand and shade of resin composites, and there was a significant interaction between two independent variables (p < 0.05). On the basis of the multiple regression analysis, in which ΔE*ab after polymerization was set as a dependent variable and ΔL*, ΔC*ab, Δa* and Δb* as independent variables, multiple correlation coefficient (r) was 0.842 and the included predictors were ΔL* [standardized partial correlation coefficient (β) = −0.760] and ΔC*ab (β = −0.715). This result indicated that the polymerization changes in color and color parameters were varied by the brand and shade of resin composites, and the polymerization color change was caused by the changes in lightness and chroma with the similar power of influence. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
The effect of chemical modification of amino acid side‐chains on collagen degradation by enzymes
Authors: Gratzer Paul F. , Santerre J. Paul , Lee J. Michael
Published: August 2006

In this study, the effects of specific chemical modifications of amino acid side‐chains on the in vitro enzyme degradation of type I collagen was studied. Two monofunctional epoxides of different size and chemistry were used to modify lysine and methylglyoxal was used to modify arginine. Lysine residues were modified using glycidol, a small hydrophilic reagent or n‐butylglycidylether, a larger hydrophobic reagent. Amino acid analysis, swelling measurements, in vitro enzyme degradation analyses (using either collagenase, trypsin, acetyltrypsin, or cathepsin B), and gel chromatography were used to determine the effects of each chemical modification on purified type I collagen.

Collagen solubilization by enzymes depended upon the size and chemistry of epoxides used to modify lysine residues. Modification of lysine residues by glycidol and arginine modification by methylglyoxal together significantly reduced collagen solubilization by acetyltrypsin and collagenase, whereas increased collagen solubilization was observed for all enzymes after lysine modification with n‐butylglycidylether combined with arginine modification by methylglyoxal. Gel chromatographic analyses of collagen fragments solubilized by acetyltrypsin from type I collagen revealed that both the extent of solubilization and sites of cleavage were altered after lysine and arginine modification. In contrast, lysine and arginine modification only altered the amount of collagen solubilized by collagenase and had no effect on the amount collagen solubilized by cathepsin B. The ability to modulate the enzyme degradation of collagen‐based materials as demonstrated in this study may facilitate the design of novel scaffolds for tissue regeneration or collagen‐based drug/protein/gene delivery systems. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Comparative evaluation of heating ability and biocompatibility of different ferrite‐based magnetic fluids for hyperthermia application
Authors: Pradhan Pallab , Giri Jyotsnendu , Samanta Gopal , Sarma Haladhar Dev , Mishra Kaushala Prasad , Bellare Jayesh , Banerjee Rinti , Bahadur Dhirendra
Published: August 2006

In this study, lauric acid‐coated, superparamagnetic, nanoparticle‐based magnetic fluids of different ferrites (Fe3O4, MnFe2O4, and CoFe2O4) were prepared and compared in terms of heating ability and biocompatibility to evaluate the feasibility of use in hyperthermia treatment of cancer. All the magnetic fluids prepared had particles of average sizes 9–11 nm. Heating ability of these magnetic fluids was evaluated by calorimetric measurement of specific absorption rate (SAR) at 300 kHz frequency and 15 kA/m field. Fe3O4 and MnFe2O4 showed higher SAR (120 and 97 W/g of ferrite, respectively) than CoFe2O4 (37 W/g of ferrite).In vitro study on BHK 21 cell lines showed dose‐dependent cell viability for all the magnetic fluids. Threshold‐biocompatible ferrite concentration for all the magnetic fluids was 0.1 mg/mL. Above 0.2 mg/mL, CoFe2O4 was more toxic than the other magnetic fluids. On intravenous injection of different doses (50, 200, and 400 mg/kg body weight) of magnetic fluids in mice, no significant changes in hematological and biochemical parameters were observed for Fe3O4 and MnFe2O4. With CoFe2O4, an increase in SGPT levels at a dose rate of 400 mg/kg body weight was observed, indicating its mild hepatotoxic effect. However, histology of different vital organs showed no pathological changes for all the three magnetic fluids. Further, long term in vivo evaluation of biocompatibility of the lauric acid‐coated ferrites is warranted. This study shows that lauric acid‐coated, superparamagnetic Fe3O4 and MnFe2O4 may be used for hyperthermia treatment and are to be preferred over CoFe2O4. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Adhesion of mouse fibroblasts on hexamethyldisiloxane surfaces with wide range of wettability
Authors: Wei Jianhua , Yoshinari Masao , Takemoto Shinji , Hattori Masayuki , Kawada Eiji , Liu Baolin , Oda Yutaka
Published: August 2006

Surface wettability is an important physicochemical property of biomaterials, and it would be more helpful for understanding this property if a wide range of wettability are employed. This study focused on the effect of surface wettability on fibroblast adhesion over a wide range of wettability using a single material without changing surface topography. Plasma polymerization with hexamethyldisiloxane followed by oxygen (O2)‐plasma treatment was employed to modify the surfaces. The water contact angle of sample surfaces varied from 106° (hydrophobicity) to almost 0° (super‐hydrophilicity). O2 functional groups were introduced on polymer surfaces during O2‐plasma treatment. The cell attachment study confirmed that the more hydrophilic the surface, the more fibroblasts adhered in the initial stage that includes super‐hydrophilic surfaces. Cells spread much more widely on the hydrophilic surfaces than on the hydrophobic surfaces. There was no significant difference in fibroblast proliferation, but cell spreading was much greater on the hydrophilic surfaces. The fibronectin adsorbed much more on a hydrophilic surface while albumin dominated on a hydrophobic surface in a competing mode. These findings suggest the importance of the surface wettability of biomaterials on initial cell attachment and spreading. The degree of wettability should be taken into account when a new biomaterial is to be employed. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Mutual wear evaluation of resin composites when opposing enamel and dentin
Authors: Suzuki Shiro , Wood M. B.
Published: August 2006

Mutual wear rates of resin composites and both superficial and deep layers of enamel and dentin were investigated by means of an in vitro wear test. Occlusal surfaces of extracted molars were ground flat to respective layers of enamel and dentin. Hemispherical‐shaped styli (n = 8) made of microfilled and microhybrid composites were placed perpendicular to the finished tooth surface (600 grit) in the presence of tap water, and a two‐body wear test (75 N load and 1.2 Hz) was performed for 100,000 cycles. The wear depths on both tooth and composite specimens were determined, and the data were statistically analyzed by two‐way ANOVA and Boneferroni test (p < 0.05). The values of deep and superficial dentin specimens against Esthet‐X (530.2 ± 213.0 μm and 717.4 ± 309.6 μm) were significantly greater than those against Epic‐TMPT (34.1 ± 17.6 μm and 29.3 ± 10.8 μm). The values of Esthet‐X against dentin were the smallest (2.4–2.6 μm), followed by those of the same material against enamel (5.5–6.1 μm), and those of Epic‐TMPT against enamel (7.2–7.9 μm). It was concluded that the wear rates of dentin varied with the type of composite used while those of enamel showed the consistency. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Human mesenchymal progenitor cell responses to a novel textured poly(L‐lactide) scaffold for ligament tissue engineering
Authors: Heckmann Leslie , Schlenker Heiter‐Julian , Fiedler Jörg , Brenner Rolf , Dauner Martin , Bergenthal Gerolf , Mattes Thomas , Claes Lutz , Ignatius Anita
Published: August 2006

Biocompatibility and cell seeding capability of a new cell scaffold made of textured polylactic acid (PLA) fibers was investigated as a new material for tissue engineering of anterior cruciate ligaments (ACL). Adhesion and proliferation of human mesenchymal progenitor cells (MPC) was investigated after 15 days by scanning electron microscopy and standard histology. Expression of collagen type I and III, fibronectin, tenascin C, decorin, smooth muscle actin, and the matrix metalloproteinases MMP‐1 and MMP‐2, as well as their tissue inhibitors TIMP‐1 and TIMP‐2 was analyzed using real‐time PCR. Protein expression of collagen I and III, tenascin C, and proliferating nuclear antigen (PCNA) was determined by immunohistology. Apoptosis was analyzed by detection of p53 expression and TUNEL staining. MPC seeded the scaffold homogeneously and showed good cell growth and no increased rate of apoptosis. After 15 days, the matrix forming genes collagen type I, tenascin C, and decorin were upregulated, indicating the formation of a ligament‐like matrix. MMP‐1 and TIMP‐1 were also significantly increased, suggesting initial matrix remodeling. It was concluded that the new porous PLA scaffold allowed homogeneous cell seeding, a fibroblastic phenotype and the production of a ligament‐like matrix and, therefore, might be a suitable cell carrier for ACL tissue engineering. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
A preliminary report on a novel electrospray technique for nanoparticle based biomedical implants coating: Precision electrospraying
Authors: Kumbar Sangamesh G. , Bhattacharyya Subhabrata , Sethuraman Swaminathan , Laurencin Cato T.
Published: August 2006

The compatibility and biological efficacy of biomedical implants can be enhanced by coating their surface with appropriate agents. For predictable functioning of implants in situ, it is often desirable to obtain an extremely uniform coating thickness without effects on component dimensions or functions. Conventional coating techniques require rigorous processing conditions and often have limited adhesion and composition properties. In the present study, the authors report a novel precision electrospraying technique that allows both degradable and nondegradable coatings to be placed. Thin metallic slabs, springs, and biodegradable sintered microsphere scaffolds were coated with poly(lactide‐co‐glycolide) (PLAGA) using this technique. The effects of process parameters such as coating material concentration and applied voltage were studied using PLAGA and poly(ethylene glycol) coatings. Morphologies of coated surfaces were qualitatively characterized by scanning electron microscopy. Qualitative observations suggested that the coatings were composed of particles of various size/shape and agglomerates with different porous architectures. PLAGA coatings of uniform thickness were observed on all surfaces. Spherical nanoparticle poly(ethylene glycol) coatings (462–930 nm) were observed at all concentrations studied. This study found that the precision electrospraying technique is elegant, rapid, and reproducible with precise control over coating thickness (μm to mm) and is a useful alternative method for surface modification of biomedical implants. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Highly porous 3D nanofiber scaffold using an electrospinning technique
Authors: Kim GeunHyung , Kim WanDoo
Published: August 2006

A successful 3D tissue‐engineering scaffold must have a highly porous structure and good mechanical stability. High porosity and optimally designed pore size provide structural space for cell accommodation and migration and enable the exchange of nutrients between the scaffold and environment. Poly(ϵ‐carprolactone) fibers were electrospun using an auxiliary electrode and chemical blowing agent (BA), and characterized according to porosity, pore size, and their mechanical properties. We also investigated the effect of the BA on the electrospinning processability. The growth characteristic of human dermal fibroblasts cells cultured in the webs showed the good adhesion with the blown web relative to a normal electrospun mat. The blown nanofiber web had good tensile properties and high porosity compared to a typical electrospun nanofiber scaffold. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Effects of incorporating nanosized calcium phosphate particles on properties of whisker‐reinforced dental composites
Authors: Xu Hockin H. K. , Sun Limin , Weir Mike D. , Takagi Shozo , Chow Laurence C. , Hockey Bernard
Published: August 2006

Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically‐strong and caries‐inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1–56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean ± SD; n = 5) decreased from 174 ± 26 MPa to 138 ± 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 ± 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 ± 0.04 mmol/L to 1.74 ± 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 ± 0.21 mmol/L to 9.95 ± 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction vMCPM in the resin: [Ca]= 42.9 v, and [PO4] = 48.7 v. In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca‐ and PO4‐releasing composites with mechanical properties matching or exceeding a commercial stress‐bearing, nonreleasing composite. This method may be applicable to the use of other Ca–PO4 fillers in developing composites with high stress‐bearing and caries‐preventing capabilities, a combination not yet available in any dental materials. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Simulation of polyethylene wear in ankle joint prostheses
Authors: Bell Carol J. , Fisher John
Published: August 2006

The performance of total ankle replacements (TARs) have not been comparable to those of the other major joints of the lower extremity. The aim of this work was to develop a new simulator test to compare the wear of a new mobile bearing TAR (Mobility) with one with a good clinical history, the Buechel Pappas, using kinematic inputs derived from the literature. The wear rate for the Mobility components was lower than that for the Buechel‐Pappas ankle joints at all time points. The wear rate for both sets of components increased with the inclusion of an anterior/posterior displacement in the kinematic inputs. This was expected as the components are subjected to higher kinematic demands and reproduces similar effects found in knee prostheses. This study has demonstrated that it is possible to study wear of TARs in a modified simulator originally designed for total knee replacements. It was also shown that the new Mobility ankle compares favorably with the Buechel Pappas ankle, which has a successful clinical history, under the simulator test conditions described. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Radiation synthesis of poly(ethylene glycol)/acrylic acid hydrogel as carrier for site specific drug delivery
Authors: Ali Amr El‐Hag , Hegazy El‐Sayed A.
Published: August 2006

pH‐sensitive hydrogels were prepared from poly(ethylene glycol) (PEG) and acrylic acid (AAc) in aqueous solution employing γ‐radiation‐induced copolymerization and crosslinking. The swelling behavior of the prepared hydrogels was determined by investigating the time and pH‐dependent swelling of the (PEG/AAc) hydrogels of different PEG content. The effect of environmental parameters such as pH and ionic strength on the swelling kinetics was studied. The results not only show the dependence of the swelling indices on the pH value of the swelling medium but also show a clear dependence of the diffusion coefficient on the ionic strength of the medium. To estimate the ability of the prepared copolymer to be used as a colon‐specific drug carrier, the release of ketoprofen was studied as a function of time at pH 1 and pH 7. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Preparation and characterization of porous PDLLA/HA composite foams by supercritical carbon dioxide technology
Authors: Teng Xinrong , Ren Jie , Gu Shuying
Published: August 2006

A 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

Implants 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

Poly(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

Nanoengineered 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

The 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

Poly(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

In 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

Background

Foot‐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 methods

In 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.

Results

Electroporation 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.

Conclusions

These 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

The 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

The 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

Upon 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

The 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

The 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

Hepatitis 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

There 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.