bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission electron microscopy and electron diffraction study of BSA‐loaded quaternized chitosan nanoparticles
Authors: Wan A‐jun , Sun Yan , Li Wen‐tao , Li Hui‐li
Published: December 2007

Chitosan nanoparticles, O‐(2‐hydroxyl) propyl‐3‐trimethyl ammonium chitosan chloride (O‐HTCC) nanoparticles and bovine serum albumin (BSA) loaded chitosan and O‐HTCC nanoparticles of a size (about 200–600 nm) were obtained through the process of ionic gelation between chitosan or O‐HTCC and sodium tripolyphosphate (TPP). The physicochemical properties of nanoparticles made from chitosan, O‐HTCC, BSA loaded chitosan, and BSA loaded O‐HTCC were determined by transmission electron microscopy (TEM), polarized optical microscopy (POM), photon correlation spectroscopy (PCS), and X‐ray diffraction (XRD) pattern. Zeta potential was also performed to understand the surface properties of nanoparticles and their ability to bind negatively charged BSA. TEM, POM, and XRD suggested that ionic‐gelation process significantly influenced the crystallinity of BSA, and greater chain realignment in the BSA‐loaded chitosan and O‐HTCC nanoparticles. PCS revealed that BSA‐loaded chitosan nanoparticles were bigger than chitosan nanoparticles in size and BSA‐loaded O‐HTCC nanoparticles were smaller than O‐HTCC nanoparticles in size. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Polypeptide‐catalyzed silica for dental applications
Authors: Advincula Maria C. , Patel Pritesh , Mather Patrick T. , Mattson Tyler , Goldberg A. Jon
Published: December 2007

Polypeptides such as polylysine have been shown to catalyze the condensation and direct the structure of silica from precursor solutions under ambient conditions. Several of the reaction parameters have been shown to mediate this activity. Specifically, mechanical perturbation seems to play a role in the formation of hierarchical structures. Most studies have been conducted in solution, but biomedical and particularly dental applications will likely require control of biosilicified coatings, films or particle formation on surfaces. Tetraethylorthosilicate was reacted with polylysine and then spin coated onto a surface. The process parameters catalyst structure, pH, buffer: ethanol ratio and percentage of cocatalyst polyethyleneimine were varied to determine their effects on the formed silica. The chemical nature and morphology of the silica were investigated with FTIR and SEM, respectively and reaction rates were monitored with a colorimetric assay. Our results show that these process parameters had only minor effects on composition, but the catalyst conformation influenced the degree of hydration while the pH, choice of solvent and cocatalyst strongly influenced morphology. We also found that perturbation from spin coating significantly influences the silicification dynamics. The ability to catalyze nano‐ to micron‐sized mineral with different morphologies using polypeptides could have numerous dental applications including, sealing of dentin tubules, in situ reinforcement of resin interfaces or preparation of implant surfaces. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
In vivo response of porous hydroxyapatite and β‐tricalcium phosphate prepared by aqueous solution combustion method and comparison with bioglass scaffolds
Authors: Ghosh Samir K. , Nandi Samit K. , Kundu Biswanath , Datta Someswar , De Dipak K. , Roy Sujit K. , Basu Debabrata
Published: December 2007

Pure hydroxyapatite (HAp) and a biphasic calcium phosphate [containing 90% of β‐tri‐calcium phosphate (β‐TCP) and 10% HAp] were tailored through an aqueous solution combustion synthesis. Porous struts were prepared using all the powders along with bioglass, a known bioactive material, and subsequently characterized. Sterilized struts were implanted to the lateral side of radius bone of 24 black Bengal goats of either sex, in which a blank hole was left unfilled in a group of six specimens to act as control. The bone formation response of the three implanting materials in vivo has been studied using scanning electron microscope and histological analysis in contrast with positive controls. Push‐out tests were used to assess the mechanical strength at the bone–biomaterial interface. It was observed that interfacial response was strongly dependent on combinations of different physical and chemical parameters. The surface of β‐TCP exhibited similar characteristics of bone and was distinct from those of intervening apatite layer of bioglass. Lower bone ingrowth and reduced strength was observed with HAp compared to β‐TCP/bioglass‐based implants. Bone formation response of the Ca‐P material varied according to the composition of the implanting material, which could be tailored through this novel synthesis. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Adhesion to chondroitinase ABC treated dentin
Authors: Mazzoni Annalisa , Pashley David H. , Ruggeri Alessandra , Vita Francesca , Falconi Mirella , Di Lenarda Roberto , Breschi Lorenzo
Published: December 2007

Dentin bonding relies on complete resin impregnation throughout the demineralised hydrophilic collagen mesh. Chondroitin sulphate‐glycosaminoglycans are claimed to regulate the three‐dimensional arrangement of the dentin organic matrix and its hydrophilicity. The aim of this study was to investigate bond strength of two etch‐and‐rinse adhesives to chondroitinase ABC treated dentin. Human extracted molars were treated with chondroitinase ABC and a double labeling immunohistochemical technique was applied to reveal type I collagen and chondroitin 4/6 sulphate distribution under field emission in‐lens scanning electron microscope. The immunohistochemical technique confirmed the effective removal of chondroitin 4/6 sulphate after the enzymatic treatment. Dentin surfaces exposed to chondroitinase ABC and untreated specimens prepared on untreated acid‐etched dentin were bonded with Adper Scotchbond Multi‐Purpose or Prime and Bond NT. Bonded specimens were submitted to microtensile testing and nanoleakage interfacial analysis under transmission electron microscope. Increased mean values of microtensile bond strength and reduced nanoleakage expression were found for both adhesives after chondroitinase ABC treatment of the dentin surface. Adper Scotchbond Multi‐Purpose increased its bond strength about 28%, while bonding made with Prime and Bond NT almost doubled (92% increase) compared to untreated specimens. This study supports the hypothesis that adhesion can be enhanced by removal of chondroitin 4/6 sulphate and dermatan sulphate, probably due to a reduced amount of water content and enlarged interfibrillar spaces. Further studies should validate this hypothesis investigating the stability of chondroitin 4/6 and dermatan sulphate‐depleted dentin bonded interface over time. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Iodine inhibits antiadhesive effect of PEG: Implications for tissue engineering
Authors: Macario Danielle K. , Entersz Ildiko , Bolikal Durgadas , Kohn Joachim , Nackman Gary B.
Published: December 2007

Background:

The success of a biomaterial implant may be affected by the surface chemistry's impact on protein adsorption. We have developed a series of poly(ethylene glycol) (PEG) containing, tyrosine‐derived polycarbonates, which have been rendered radio‐opaque by the iodination of tyrosine units in the copolymer backbone for use in resorbable biomedical implants including vascular stents and grafts. We tested the hypothesis that protein adsorption along with seeding, growth, and migration of human aortic smooth muscle cells (SMC) and human aortic endothelial cells (EC) will be modified by the presence of iodine and PEG within the polymer composition.

Methods:

Thin films of these polymers were prepared for the protein‐material and cell‐material interaction studies. Dot blot, SDS‐PAGE, and XPS were used to evaluate relative protein adsorption. Cell adhesion and growth studies were performed using an MTS assay. Cell migration was evaluated using an injury model.

Results:

The presence of PEG attenuated protein adsorption, cell adhesion, and growth. With the subsequent incorporation of iodine, protein adsorption markedly increased while the antiadhesive effect of PEG was counteracted by iodine for EC and SMC adhesion and SMC growth.

Conclusion:

Iodine incorporation into the polymer resulted in increased protein adsorption thus counteracting the effect of PEG. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Mechanical property, degradation rate, and bone cell growth of chitosan coated titanium influenced by degree of deacetylation of chitosan
Authors: Yuan Youling , Chesnutt Betsy M. , Wright Lee , Haggard Warren O. , Bumgardner Joel D.
Published: December 2007

Chitosan has shown promise as a coating for dental/craniofacial and orthopaedic implants. However, the effects of degree of deacetylation (DDA) of chitosan on coating bond strength, degradation, and biological performance is not known. The aim of this project was to evaluate bonding, degradation, and bone cell growth on titanium coated with chitosans of different DDA and from different manufacturers. Three different chitosans, 80.6%, 81.7%, and 92.3% DDA were covalently bonded to titanium coupons via silane‐glutaraldehyde molecules. Bond strengths were evaluated in mechanical tensile tests, and degradation, over 5 weeks, was conducted in cell culture medium with and without 100 μg/mL lysozyme. Cytocompatibility was evaluated for 10 days using UMR 106 osteoblastic cells. Results showed that mean chitosan coating bond strengths ranged from 2.2–3.8 MPa, and that there was minimal affect of DDA on coating bond strengths. The coatings exhibited little dissolution over 5 weeks in medium with or without lysozyme. However, the molecular weight (MW) of the chitosan coatings remaining on the titanium samples after 5 weeks decreased by 69–85% with the higher DDA chitosan coatings exhibiting less percent change in MW than the lower DDA materials. The growth of the UMR 106 osteoblast cells on the 81.7% DDA chitosan coating was lower on days 3 and 5, as compared with the other two coatings, but by day 10, there were no differences in growth among three coatings or to the uncoated titanium controls. Differences in growth were attributed to differences in manufacturer source material, though all coatings were judged to be osteocompatible in vitro. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Fatigue crack propagation rates in PMMA bone cement cannot be reduced to a single power law
Authors: Race Amos , Mann Kenneth A.
Published: December 2007

Cement mantles around metallic implants have pre‐existing flaws (shrinkage induced cracks, laminations, and endosteal surface features) and their fatigue failure is related to the fatigue crack propagation (FCP) rate of bone cement. We estimated the relevant in vivo range of cyclic stress intensity factor (ΔK) around a generic femoral stem (0–1 MPa √m) and determined that previous FCP data did not adequately cover this range of ΔK. Vacuum‐mixed standard bone cement was machined into ASTM E647 standard compact notched tension specimens. These were subject to sinusoidal loading (R = 0.1) at 5 Hz in 37°C DI water, covering a ΔK range of 0.25–1.5 MPa √m (including a decreasing ΔK protocol). FCP‐rate data is normally reduced to a power‐law fit relating crack growth rate (da/dn) to ΔK. However, a substantial discontinuity was observed in our data at around ΔK = 1, so two power‐law fits were used. Over the physiologically plausible range of ΔK, cracks grew at a rate of 2.9 E −8 × ΔK2.6 m/cycle. Our data indicated that FCP‐rates for 0.5 > ΔK > 0.3 MPa √m are between 10 E −8 and 10 E −8 m/cycle, 1 or 2 orders of magnitude greater than predicted by extrapolating from previous models based on higher ΔK data. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Effect of temporary filling materials on repair bond strengths of composite resins
Authors: Erdemir Ali , Eldeniz Ayce Unverdi , Belli Sema
Published: December 2007

Endodontic access cavities sometimes can be prepared through a permanent composite restoration. Between the appointments, temporary cements are used to seal access cavities and may have negative effect on bonding of further composite restoration. The purpose of this study was to compare shear bond strength of composite to composite which had been in contact with various temporary filling materials. Standard cavities were prepared on 160 acrylic resin blocks, obturated with composite resin (Clearfil AP‐X, Kuraray, Japan) and randomly divided into eight groups (n = 20). Group 1 received no treatment. From group 2–8, composite surfaces were covered with the following cements temporarily: Zinc‐oxide/calcium‐sulphate (Cavit‐G, ESPE, Germany), two different Zinc‐Oxide‐Eugenol materials (ZnOE, Cavex, Holland and IRM, Dentsply, USA), Zinc‐phosphate cement (Adhesor, Spofa‐Dental, Germany), Zinc‐polycarboxylate cement (Adhesor‐Carbofine, Spofa‐Dental, Germany), Glass‐Ionomer‐Cement (Argion‐Molar, Voco, Germany), or light curing temporary material (Clip, Voco, Germany). The cements were removed mechanically after 1 week storage in distilled water at 37°C and composite surfaces were treated with a self‐etch adhesive system (SE‐Bond, Kuraray, Japan). Composite resin build‐ups were created on composite surfaces. Shear bond strength values were measured using universal testing machine at crosshead speed of 1 mm/min. The data was calculated in MPa and statistically analyzed using one‐way ANOVA and Tukey tests. Eugenol‐containing cements significantly reduced shear bond strengths of composite to composite (p < 0.05), while the other temporary materials had no adverse effect on shear bond strength (p > 0.05). These findings suggested that temporary filling materials except eugenol‐containing materials have no negative effect on composite repair bond strengths. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Influences of passivating elements on the corrosion and biocompatibility of super stainless steels
Authors: Yoo Young‐Ran , Jang Soon‐Geun , Oh Keun‐Taek , Kim Jung‐Gu , Kim Young‐Sik
Published: December 2007

Biometals need high corrosion resistance since metallic implants in the body should be biocompatible and metal ion release should be minimized. In this work, we designed three kinds of super stainless steel and adjusted the alloying elements to obtain different microstructures. Super stainless steels contain larger amounts of Cr, Mo, W, and N than commercial alloys. These elements play a very important role in localized corrosion and, thus, their effects can be represented by the “pitting resistance equivalent number (PREN).” This work focused on the behavior which can arise when the bare surface of an implant in the body is exposed during walking, heavy exercise, and so on. Among the experimental alloys examined herein, Alloy Al and 316L stainless steels were mildly cytotoxic, whereas the other super austenitic, duplex, and ferritic stainless steels were noncytotoxic. This behavior is primarily related to the passive current and pitting resistance of the alloys. When the PREN value was increased, the passivation behavior in simulated body solution was totally different from that in acidic chloride solution and, thus, the Cr2O3/Cr(OH)3 and [Metal oxide]/[Metal + Metal oxide] ratios of the passive film in the simulated body solution were larger than those in acidic chloride solution. Also, the critical current density in simulated body solution increased and, thus, active dissolution may induce metal ion release into the body when the PREN value and Ni content are increased. This behavior was closely related to the presence of EDTA in the simulated body solution. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Novel extracellular matrix for cell sheet recovery using genetically engineered elastin‐like protein
Authors: Mie Masayasu , Mizushima Yasunori , Kobatake Eiry
Published: December 2007

Elastin‐like peptides (ELPs) sequences are repeats of the pentapeptide GVGVP, and they have the ability to coaggregate reversibly, depending on the temperature. By exploiting this characteristic, a novel extracellular matrix protein (ECM) containing ELP was developed genetically to harvest a cell sheet from a culture dish. One of the ELP constructs, G288, consisted of 288 repeats of the sequence GVGVGP (G); it was attached to a hydrophobic dish surface. Next, cells with the sequence His‐G36RG36, which has a His tag and an RGD sequence (R) that promotes attachment of the cell between the G36 sequences, consisted of 36 repeats of the sequence GVGVP, were added to the dish. After these cells became confluent, the temperature was changed to 20°C in order to reverse the coaggregation. At this temperature, cells could be detached from the dish as a cell sheet. This genetically engineering method for construction of thermoresponsive ECM would be suitable to modify ECM with further functional domains. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Adhesion of a self‐etching system to dental substrate prepared by Er:YAG laser or air abrasion
Authors: Souza‐Zaroni Wanessa C. , Chinelatti Michelle A. , Delfino Carina S. , Pécora Jesus D. , Palma‐Dibb Regina G. , Corona Silmara A. M.
Published: December 2007

The purpose of this study was to assess the microtensile bond strength of a self‐etching adhesive system to enamel and dentin prepared by Er:YAG laser irradiation or air abrasion, as well as to evaluate the adhesive interfaces by scanning electron microscopy (SEM). For microtensile bond strength test, 80 third molars were randomly assigned to five groups: Group I, carbide bur, control (CB); II, air abrasion with standard tip (ST); III, air abrasion with supersonic tip (SP); IV, Er:YAG laser 250 mJ/4 Hz (L250); V, Er:YAG laser 300 mJ/4 Hz (L300). Each group was divided into two subgroups (n = 8) (enamel, E and dentin, D). E and D surfaces were treated with the self‐etching system Adper Prompt L‐Pop and composite buildups were done with Filtek Z‐250. Sticks with a cross‐sectional area of 0.8 mm2 (±0.2 mm2) were obtained and the bond strength tests were performed. Data were submitted to ANOVA and Tukey's test. For morphological analysis, disks of 30 third molars were restored, sectioned and prepared for SEM. Dentin presented the highest values of adhesion, differing from enamel. Laser and air‐abrasion preparations were similar to enamel. Dentin air‐abrasion with standard tip group showed higher bond strength results than Er:YAG‐laser groups, however, air‐abrasion and Er:YAG laser groups were similar to control group. SEM micrographs revealed that, for both enamel and dentin, the air‐abrasion and laser preparations presented irregular adhesive interfaces, different from the ones prepared by rotary instrument. It was concluded that cavity preparations accomplished by both Er:YAG laser energies and air abrasion tips did not positively influence the adhesion to enamel and dentin. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Polypeptide nanocoatings for preventing dental and orthopaedic device‐associated infection: pH‐induced antibiotic capture, release, and antibiotic efficacy
Authors: Jiang Bingbing , Li Bingyun
Published: December 2007

Implant‐associated infection is one of the most common and problematic complications for dental and orthopaedic patients. Modification of currently used implant surfaces aimed at bestowing them with antibacterial properties is a promising approach in the development of new biomaterials. In this study, a novel nanotechnology, that is, electrostatic self‐assembly, was developed to construct biomimetic polypeptide nanocoatings on commonly used metal implants. A model antibacterial drug, cefazolin, was captured in the polypeptide nanocoating and its release was studied. We have shown that the capture and release of cefazolin was pH‐induced and could be controlled, and the developed antibiotic‐incorporated polypeptide multilayer nanocoatings could prevent Staphylococcus aureus colonization thus showing great potential for preventing implant‐associated infection. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
The electrochemical behavior and surface analysis of Ti49.6Ni45.1Cu5Cr0.3 alloy for orthodontic usage
Authors: Zheng Y.‐F. , Wang Q. Y. , Li L.
Published: December 2007

The aim of this study was to investigate the electrochemical behavior of Ti49.6Ni45.1Cu5Cr0.3 (TiNiCuCr) alloy in artificial saliva solutions with a wide rage of pH values and to characterize the surface passive film after polarization tests. This article represents the ideal, static environment and associated electrochemical response and comparison values. The corrosion behavior of TiNiCuCr alloy was systematically studied by open circuit potential, potentiodynamic, potentiostatic, and electrochemical impedance techniques. Potentiodynamic and potentiostatic test results showed that the corrosion behavior of TiNiCuCr was similar to that of NiTi alloy. Both corrosion potential (Ecorr) and pitting corrosion potential (Eb) showed a pH‐dependent tendency that Ecorr and Eb decreased with the increase of the pH value. X‐ray photoelectron spectroscopy results revealed the composition of the passive film consisted mainly of TiO2 with a little amount of Ni oxides (NiO/Ni2O3) that was identical with NiTi alloy. Besides Ni, a Cu enriched sub‐layer was also found. The nickel ion release rate showed a typical time‐related decrease as examined by ICP/OES. In conclusion, the addition of Cu and Cr had little effect on the corrosion behavior of NiTi or on the composition and the structure of the passive film. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Effect of keratin‐gelatin and bFGF‐gelatin composite film as a sandwich layer for full‐thickness skin mesh graft in experimental dogs
Authors: Thilagar S. , Jothi N. Arul , Omar A. R. Sheikh , Kamaruddin M. Y. , Ganabadi Shanthi
Published: December 2007

Skin grafts are indicated when there is a major loss of skin. Full‐thickness skin graft is an ideal choice to reconstruct defect of irregular surface that is difficult to immobilize. Full‐thickness mesh grafts can be applied to patch large skin defect when there is less donor site in extensively traumatized and burned surgical patients. The concept of using natural biomaterials such as keratin, basic fibroblast growth factor is slowly gaining popularity in the field of medical research to achieve early healing. The main objective of this study is to evaluate the efficacy of gelatin conjoined with keratin processed from the poultry feather and commercially available basic fibroblast growth factor (bFGF) as a sandwich layer in promoting the viability of full‐thickness skin mesh grafts. The efficacy was assessed from the observation of clinical, bacteriological, and histopathological findings in three groups of experimental dogs. The clinical observations such as color, appearance and discharge, and hair growth were selected as criteria which indicated good and early acceptance of graft in keratin‐gelatin (group II). On bacteriological examination, Staphylococcus aureus and Proteus was identified in few animals. Histopathological study of the patched graft revealed early presences of hair follicles; sebaceous gland, and normal thickness of the epidermis in keratin‐gelatin in group II treated animals compared with other group (group I‐control, group III‐bFGF‐gelatin). © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Preparation of a bonelike apatite–polymer fiber composite using a simple biomimetic process
Authors: Yokoyama Yoshiro , Oyane Ayako , Ito Atsuo
Published: December 2007

A bonelike apatite–polymer fiber composite may be useful as an implant material to replace bone, the enthesis of a tendon, and the joint part of a ligament. We treated an ethylene‐vinyl alcohol copolymer (EVOH) plate and knitted EVOH fibers with an oxygen plasma to produce oxygen‐containing functional groups on their surfaces. The plasma‐treated samples were alternately dipped in alcoholic calcium and phosphate ion solutions three times to deposit apatite precursors onto their surfaces. The surface‐modified samples formed a dense and uniform bonelike surface apatite layer after immersion for 24 h in a simulated body fluid with ion concentrations approximately equal to those of human blood plasma. The adhesive strength between the apatite layer and the sample's surface increased with increasing power density of the oxygen plasma. The apatite–EVOH fiber composite obtained by our process has similarities to natural bone in that apatite crystals are deposited on organic polymer fibers. The resulting composite would possess osteoconductivity due to the apatite phase. With proper polymer selection and optimized synthesis techniques, a composite could be made that would have bonelike mechanical properties. Hence, the present surface modification and coating process would be a promising route to obtain new implant materials with bonelike mechanical properties and osteoconductivity. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Prevention of postoperative adhesions by a novel honeycomb‐patterned poly(lactide) film in a rat experimental model
Authors: Fukuhira Yukako , Ito Masaya , Kaneko Hiroaki , Sumi Yoshihiko , Tanaka Masaru , Yamamoto Sadaaki , Shimomura Masatsugu
Published: December 2007

Intraperitoneal adhesion is a serious problem concerning abdominal surgery. This study evaluated the performance of a honeycomb‐patterned poly(lactide) (HCPLA) film as a physical barrier for preventing postoperative adhesion. HCPLA films were prepared using dioleoylphosphatidylethanolamine (DOPE) or a copolymer of dodecylacrylamide and ω‐carboxyhexylacrylamide (CAP) as a surfactant (HCPLA‐DOPE and HCPLA‐CAP, respectively). In an in vivo adhesion prevention experiment, male Sprague‐Dawley rats underwent standard cecum abrasion before midline laparotomy. We placed 2 cm × 2 cm HCPLA and flat films on the gliding interfaces; untreated rats formed the control group. After 1 week, adhesion was scored from 0 to 4. No significant difference was observed in the scores among groups, but macroscopic differences in adhesion prevention were observed. The adhesive strength of HCPLA‐DOPE (18.1 ± 1.2 g) to skinless chicken breast was significantly higher than that of the flat film (15.2 ± 0.8 g, p < 0.05). Further, the adhesion score after 1 week for the HCPLA‐DOPE group (1.6 ± 0.2) was significantly lower than that for the control group (3.0 ± 0.3, p < 0.05) but comparable to that for the Seprafilm™ group (1.4 ± 0.3). These results demonstrated the potential of HCPLA‐DOPE as a physical barrier for preventing postoperative adhesion. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Cumulative effect of disinfection procedures on microhardness and tridimensional stability of a poly(methyl methacrylate) denture base resin
Authors: Sartori Evandro Afonso , Schmidt Caroline Bom , Mota Eduardo Gonçalves , Hirakata Luciana Mayumi , Shinkai Rosemary Sadami Arai
Published: December 2007

Microwave irradiation has been used for disinfection of dentures instead of chemical solutions; yet, its effect on resin properties after repeated procedures still is unclear. This study evaluated the cumulative effect of two disinfection methods on Knoop microhardness and tridimensional stability of a poly(methyl methacrylate) denture base resin. For the microhardness measurement, 24‐resin discs received mechanical polishing and were submitted to the following treatments: (1) control (no disinfection), (2) chemical disinfection (immersion in 100ppm chloride solution for 24h), or (3) microwave disinfection (irradiation at 690 W for 6 min). Disinfection procedures were performed twice (T1, T2) with a 7‐day interval. Knoop microhardness was recorded after polishing (T0) and after T1 and T2. For the dimensional stability test (measured by the adaptation of the denture bases), 36‐maxillary denture bases were obtained from type III dental stone casts duplicated from a metallic master model and submitted to the disinfection treatment. Adaptation of denture bases was measured at baseline (T0) and after T1 and T2 by weighing a vinyl polysiloxane film reproducing the gap between resin base and master model. Data were analyzed by ANOVA GLM for repeated measures and Bonferroni's test, α = 0.05. Knoop microhardness was not modified by any disinfection procedure but decreased over time. Denture resin bases submitted to microwave disinfection had gradual increase of distortion over time, while bases immersed in chloride solution did not differ from the control group and remained dimensionally stable from T1 to T2. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Assessment of tissue repair in full thickness chondral defects in the rabbit using magnetic resonance imaging transverse relaxation measurements
Authors: Ramaswamy Sharan , Gurkan Ilksen , Sharma Blanka , Cascio Brett , Fishbein Kenneth W. , Spencer Richard G.
Published: December 2007

The purpose of this study was to determine if the noninvasive and nondestructive technique of magnetic resonance imaging could be used to quantify the amount of repair tissue that fills surgically‐induced chondral defects in the rabbit. Sixteen 4‐mm diameter full‐thickness chondral defects were created. A photopolymerizable hydrogel was used to seal the defects as a treatment modality. At 5 weeks, the animals were sacrificed and the distal femur was subjected to MRI analyses at high field (9.4 T). The transverse relaxation time (T2) in each defect was measured. Histology and histomorphometric analysis were used to quantify the amount of repair tissue that filled each defect. The relationship between T2 and percent tissue fill was found to fit well to a negatively sloped, linear model. The linear (Pearson's product‐moment) correlation coefficient was found to be r = −0.82 and the associated coefficient of determination was r2 = 0.67. This correlation suggests that the MRI parameter T2 can be used to track changes in the amount of repair tissue that fills cartilage defects. This would be especially useful in in vivo cartilage tissue engineering studies that attempt to determine optimal biomaterials for scaffold design. Published 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Hybrid coating of hydroxyapatite and collagen within poly(D,L‐lactic‐co‐glycolic acid) scaffold
Authors: Li Jiashen , Yuan Xiaoyan , He Fei , Mak Arthur F. T.
Published: December 2007

To improve the cell‐affinity of biodegradable polymer scaffold, coating hydroxyapatite (HA) or collagen on the surface of polymer materials seemed to be a strategy to combine both advantages of them. The objective of this study was to develop a novel method to introduce HA and collagen inside polymer scaffold uniformly. HA and collagen suspension was mixed with paraffin microspheres, and molded to form a composite sample. After the sample was dried, HA/collagen composite was left among and on the surface of paraffin microspheres. Poly(D,L‐lactic‐co‐glycolic acid) (PLGA) (50/50) solution was cast into the inter‐space of the paraffin microspheres and dried. Afterwards, the paraffin was dissolved and removed, HA/collagen was transferred to the surface and even inside of the pore wall of PLGA scaffolds. Collagen fibers and HA particles which were inlaid inside the PLGA pore wall could help to enhance the coating strength between HA/Col coating and the pore wall surface of the PLGA scaffold. The scaffolds with HA/Col coating were expected to exhibit desirable properties in bone tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Metal ion release from fracture fixation devices: A potential marker of implant failure
Authors: Savarino L. , Maci G. S. , Greco M. , Baldini N. , Giunti A.
Published: December 2007

Stainless steel is the alloy most frequently used for fracture fixation devices (FFD). We aimed to verify if the ion release evaluation could be a surrogate marker of performance and could allow an early detection of implant failure in patients with stainless steel FFD. We measured the nickel (Ni) and chromium (Cr) serum content in patients undergoing the retrieval of stainless steel plates (group I) or intramedullary nails (group II), because of consolidation or failure. Forty‐five healthy donors were recruited as controls. Furthermore, the diagnostic performance of these values was evaluated: analysis power, sensitivity, specificity, positive and negative predictive values, likelihood ratios, and diagnostic accuracy were calculated. A significant increase of ion values was demonstrated in patients with failed plates, compared with the values recorded in patients with well‐fixed plates (p = 0.002 for Cr and p = 0.002 for Ni), and in healthy subjects (p = 0.0002 for Cr and p = 0.003 for Ni). No significant difference was found between stable implants and controls (p = 0.8 for Cr and p = 0.06 for Ni). A high specificity (0.92 for Cr and 1.00 for Ni), positive predictive value (0.87 for Cr and 1.00 for Ni), and positive likelihood ratio (9.10 for Cr) were calculated for ion testing in plates. The substantial metal content elevations in patients with plates and the positive likelihood ratio above 5 for chromium testing suggest that ion dosage may be a useful surrogate marker for the presence of malfunctioning of these devices, perhaps before the onset of clinical and radiographic changes. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
The effect of surface treatments on the fretting behavior of Ti‐6Al‐4V alloy
Authors: Dalmiglio Matteo , Schaaff Petra , Holzwarth Uwe , Chiesa Roberto , Rondelli Gianni
Published: December 2007

Stem modularity in total hip replacement introduces an additional taper joint between Ti‐6Al‐4V stem components with the potential for fretting corrosion processes. One possible way to reduce the susceptibility of the Ti‐6Al‐4V/Ti‐6Al‐4V interface to fretting is the surface modification of the Ti‐6Al‐4V alloy. Among the tested, industrially available surface treatments, a combination of two deep anodic spark deposition treatments followed by barrel polishing resulted in a four times lower material release with respect to untreated, machined fretting pad surfaces. The fretting release has been quantified by means of radiotracers introduced in the alloy surface by proton irradiation. In a simple sphere on flat geometry, the semispherical fretting pads were pressed against flat, dog‐bone shaped Ti‐6Al‐4V fatigue samples cyclically loaded at 4 Hz. In this way a cyclic displacement amplitude along the surfaces of 20 μm has been achieved. A further simplification consisted in the use of deionized water as lubricant. A comparison of the radiotracer results with an electrochemical material characterization after selected treatments by potentiostatic tests of modular stems in 0.9% NaCl at 40°C for 10 days confirmed the benefit of deep anodic spark deposition and subsequent barrel polishing for improving the fretting behavior of Ti‐6Al‐4V. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Globally convergent computation of chemical equilibrium composition
Authors: Patil Sunil , Aiyer R. C. , Sharma K. C.
Published: December 2007

We report the Newton–Raphson based globally convergent computational method for determination of chemical equilibrium composition. In the computation of chemical equilibrium composition, an appearance of nonpositive value of number of moles of any component leads to discrepancy. The process of conditional backtracking and adaptive set of refining factors for Newton–Raphson steps are employed to resolve the problem. The mathematical formulation proposed by Heuze et al. (J Chem Phys 1985, 83, 4734) has been solved using proposed computational method, instead of empirical iterative formulation, as proposed by them. Results for the same numerical example, used by Heuze et al. (J Chem Phys 1985, 83, 4734) and White et al. (J Chem Phys 1958, 28, 751) are presented in addition to decomposition of Cyclotrimethylenetrinitramine for fixed temperature and pressure. It is observed that the proposed method is efficient and globally convergent. An even noteworthy finding is that the set of refining factors can be chosen from the range 0.1 to η, where η may be greater than one depending on how smoothly system of nonlinear equations is dependant on corresponding variable. Related analysis and results are discussed. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
A dual‐level state‐specific time‐dependent density‐functional theory
Authors: Tokura Seiken , Sato Takeshi , Tsuneda Takao , Nakajima Takahito , Hirao Kimihiko
Published: December 2007

A highly efficient new algorithm for time‐dependent density‐functional theory (TDDFT) calculations is presented. In this algorithm, a dual‐level approach to speed up DFT calculations (Nakajima and Hirao, J Chem Phys 2006, 124, 184108) is combined with a state‐specific (SS) algorithm for TDDFT (Chiba et al., Chem Phys Lett 2006, 420, 391). The dual‐level SS‐TDDFT algorithm was applied to excitation energy calculations of typical small molecules, the Q bands of the chlorophyll A molecule, the charge‐transfer energy of the zincbacteriochlorin–bacteriochlorin model system, and the lowest‐lying excitation of the circumcoronene molecule. As a result, it was found that the dual‐level SS‐TDDFT gave correct excitation energies with errors of 0.2–0.3 eV from the standard TDDFT approach, with much lower CPU times for various types of excitation energies of large‐scale molecules. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Molecular dynamics of a calix[4]arene‐containing polymer in dichloromethane solution: Ability of the solvent molecules to fill the cavity of the macrocycle
Authors: Rodríguez‐Ropero Francisco , Zanuy David , Alemán Carlos
Published: December 2007

The structure and dynamics of the dichloromethane solvent around the calix[4]arene units contained in the molecular actuator poly(calix[4]arene bis‐bithiophene) have been examined using a 1‐μs molecular dynamics simulation. Results indicate that a solvent molecule fills the cavity associated to the cone conformation of the macrocycle during a significant period of time, especially when the actuator is not contracted. The position of such solvent molecule presents a fourfold symmetry with a maximum orientation toward the center of each ring contained in the calix[4]arene. Frequently, the solvent molecule located inside the cavity is rapidly exchanged for another molecule of the bulk. Thus, the number of dichloromethane molecules that reside more than 0.5 ns inside the cavity is relatively small. Finally, we detected that a significant number of solvent molecules are able to migrate from the cavity of one calix[4]arene to the cavity/ies of other/s, suggesting that the dynamics of the bulk solvent is important for the formation of these inclusion complexes. © 2007 Wiley Periodicals, Inc.J Comput Chem, 2008
Assessment of performance of the general purpose polarizable force field QMPFF3 in condensed phase
Authors: Donchev Alexander G. , Galkin Nikolay G. , Illarionov Alexey A. , Khoruzhii Oleg V. , Olevanov Michael A. , Ozrin Vladimir D. , Pereyaslavets Leonid B. , Tarasov Vladimir I.
Published: December 2007

The recently introduced force field (FF) QMPFF3 is thoroughly validated in gas, liquid, and solid phases. For the first time, it is demonstrated that a physically well‐grounded general purpose FF fitted exclusively to a comprehensive set of high level vacuum quantum mechanical data applied as it is to simulation of condensed phase provides high transferability for a wide range of chemical compounds. QMPFF3 demonstrates accuracy comparable with that of the FFs explicitly fitted to condensed phase data, but due to high transferability it is expected to be successful in simulating large molecular complexes. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Fundamental vibrational frequencies and dominant resonances in methylamine isotopologues by ab initio and density functional theory methods
Authors: Levi Chen , Martin Jan M. L. , Bar Ilana
Published: December 2007

Ab initio and density functional theory (DFT) calculations were performed for obtaining fundamental vibrational frequencies of methylamine, CH3NH2, and its deuterated variants CH3ND2, CD3NH2, and CD3ND2. The calculations were carried out using the CCSD(T) coupled cluster approximation with cc‐pVTZ and cc‐pVQZ basis sets, and by the DFT method with the semiempirical hybrid functional B97‐1 with polarization consistent pc‐2 and pc‐3 basis sets. Reasonable performance of the DFT harmonic and ab initio harmonic calculations was found, which improved considerably upon combination of the harmonic fundamental frequencies with anharmonic corrections from the smaller, pc‐2, basis. The computed anharmonic fundamental frequencies of methylamine isotopologues agree very well with the experimental values and represent a useful tool for assignment and analysis of the dominant resonances. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Structure and singly occupied molecular orbital analysis of anionic tautomers of guanine
Authors: Haranczyk Maciej , Holliday John , Willett Peter , Gutowski Maciej
Published: December 2007

Recently, we reported the discovery of adiabatically bound anions of guanine that might be involved in the processes of DNA damage by low‐energy electrons and in charge transfer through DNA. These anions correspond to some tautomers that have been ignored thus far. They were identified using a hybrid quantum mechanical–combinatorial approach in which an energy‐based screening was performed on the library of 499 tautomers with their relative energies calculated with quantum chemistry methods. In the current study, we analyze the adiabatically bound anions of guanine in two aspects: (1) the geometries and excess electron distributions are analyzed and compared with anions of the most stable neutrals to identify the sources of stability; (2) the chemical space of guanine tautomers is explored to verify if these new tautomers are contained in a particular subspace of the tautomeric space. The first task involves the development of novel approaches—the quantum chemical data like electron density, orbital, and information on its bonding/antibonding character are coded into holograms and analyzed using chemoinformatics techniques. The second task is completed using substructure analysis and clustering techniques performed on molecules represented by 2D fingerprints. The major conclusion is that the high stability of adiabatically bound anions originates from the bonding character of the π orbital occupied by the excess electron. This compensates for the antibonding character that usually causes significant buckling of the ring. Also, the excess electron is more homogenously distributed over both rings than in the case of anions of the most stable neutral species. In terms of 2D substructure, the most stable anionic tautomers generally have additional hydrogen atoms at C8 and/or C2 and they do not have hydrogen atoms attached to C4, C5, and C6. They also form an “island of stability” in the tautomeric space of guanine. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Functional display of Rhizomucor miehei lipase on surface of Saccharomyces cerevisiae with higher activity and its practical properties
Authors: Zhang Wei‐Guo , Han Shuang‐Yan , Wei Dong‐Zhi , Lin Ying , Wang Xiao‐Ning
Published: December 2007

BACKGROUND: A display system, which can translate DNA to functional peptides or proteins, is used as a new protein expression system. In this system, peptides or proteins are displayed on the cell surface as a fusion form with some anchoring proteins. Yeast cells displaying lipases on their cell‐surface could be used as whole‐cell biocatalysts. This research focuses on the functional display of Rhizomucor miehei lipase (RML) on the surface of Saccharomyces cerevisiae with higher activity.

RESULTS: The lipases (RML) from R.miehei 3.4960 were of active form. The RML‐α‐agglutinin fusion proteins produced were not secreted into the culture media and were mostly immobilized on the yeast cells. Cell surface displayed lipase showed the highest activity at 45 °C and pH 8.0.

CONCLUSION: The gene encoding RML from R.miehei 3.4960 can be functionally expressed on the cell surface of S. cerevisiae MT8‐1 using a glycosylphosphatidylinositol (GPI) anchor with higher activity. Copyright © 2007 Society of Chemical Industry
Myosin regulatory light chain expression in trout muscle
Authors: Donato Megan E. , Schiavi Jonathan , Ulerich Alexis D. , Weaver Frances E. , Coughlin David J.
Published: December 2007

Muscle's contractile properties can vary along different trajectories, including between muscle fiber types, along the body (within a muscle fiber type), and between developmental stages. This study explores the role of the regulatory myosin light chain (MLC2) in modulating contractile properties in rainbow trout myotomal muscle. Rainbow trout show longitudinal variations in muscle activation and relaxation, with faster contractile properties in the anterior myotome. The expression of two muscle proteins, troponin T and parvalbumin, vary along the length of trout in concert with shifts in muscle activation and relaxation. However, there is no longitudinal variation in myosin heavy chain in trout. This study explores the role of MLC2 (or regulatory light chain), part of the myosin hexamer, in contributing to longitudinal variations in contractile properties of trout swimming muscle. We cloned and sequenced two isoforms of MLC2 from trout muscle and used real‐time quantitative polymerase chain reaction to assess the relative expression of these two isoforms in red and white muscle from different body positions of two ages of rainbow trout: parr and smolt. Longitudinal variations in slow (sMLC2) but not fast (fMLC2) regulatory light chain isoforms were observed in young trout parr but not older trout smolts. The differences in sMLC2 expression correlated with shifts in muscle contractile properties in the parr. J. Exp. Zool. 309A:64–72, 2008. © 2007 Wiley‐Liss, Inc.
PCR survey of Xenoturbella bocki Hox genes
Authors: Fritzsch Guido , Böhme Manja U. , Thorndyke Mike , Nakano Hiroaki , Israelsson Olle , Stach Thomas , Schlegel Martin , Hankeln Thomas , Stadler Peter F.
Published: December 2007

Xenoturbella bocki has recently been identified as one of the most basal deuterostomes, although an even more basal phylogenetic position cannot be ruled out. Here we report on a polymerase chain reaction survey of partial Hox homeobox sequences of X. bocki. Surprisingly, we did not find evidence for more than five Hox genes, one clear labial/PG1 ortholog, one posterior gene most similar to the PG9/10 genes of Ambulacraria, and three central group genes whose precise assignment to a specific paralog group remains open. We furthermore report on a re‐evaluation of the available published evidence of Hox genes in other basal deuterostomes. J. Exp. Zool. (Mol. Dev. Evol.) 310B:278–284, 2008. © 2007 Wiley‐Liss, Inc.