bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parallel processing in the isoelectric focusing chip
Authors: Zilberstein Gleb V. , Baskin Emmanuil M. , Bukshpan Shmuel 
Published: November 2003

AbstractInvestigation of isoelectric focusing (IEF) kinetics has been performed to provide the theoretical basis for miniaturization of classical IEF in immobilized pH‐gradients. Standard IEF demands colinearity of the electric field and pH‐gradient directions (serial devices). It is shown that the IEF separation process based on a continuous, serial pH gradient is incompatible with miniaturization of separation devices. The new realization of the IEF device by a parallel IEF chip is suggested and analyzed. The main separation tool of the device is a dielectric membrane (chip) with conducting channels that are filled by Immobiline gels of varying pH. The membrane is held perpendicular to the applied electric field and proteins are collected (trapped) in the channels whose pH are equal to the pI of the proteins. The pH value of the surrounded aqueous solution is not equal to any channel's pH. The fast particle transport between different channels takes place due to convection in the aqueous solution. The new device geometry introduces two new spatial scales to be considered: the scale of transition region from a solution to the gel in a channel and a typical channel size. The corresponding time scales defining the IEF process kinetics are analyzed and scaling laws are obtained. It is shown both theoretically and experimentally that parallel IEF accelerates the fractionation of proteins by their pI down to several minutes and enables possible efficient sample collection and purification.
Predation on Mosquito Larvae by Mesocyclops thermocyclopoides (Copepoda: Cyclopoida) in the Presence of Alternate Prey
Authors: Kumar Ram , Ramakrishna Rao T. 
Published: November 2003

AbstractThe cyclopoid copepod Mesocyclops thermocyclopoides, a dominant invertebrate predator in many shallow ponds and temporary water bodies in northern India, feeds on cladocerans, rotifers, ciliates and when present, on mosquito larvae also. We studied in the laboratory the prey consumption rates of the copepod on first and fourth instar larvae of two species of mosquito (Anopheles stephensi and Culex quinquefasciatus) in relation to their density. We also studied its prey selectivity with mosquito larvae in the presence of an alternate prey (the cladocerans‐either Moina macrocopa or Ceriodaphnia cornuta) in different proportions. With either mosquito species, the copepod actively selected Instar‐I larvae, avoiding the Instar‐IV larvae, and with either instar, selected Anopheles stephensi over Culex quinquefasciatus. When prey choice included the cladoceran as an alternate prey, the copepod selected the cladoceran only when the other prey was Instar‐IV mosquito larvae. Our results point to the potential and promise of M. thermocyclopoides as a biological agent for controlling larval populations of vectorially important mosquito species.
Haplotype Frequency Distribution in Northeastern European Saduria entomon (Crustacea: Isopoda) Populations. A Phylogeographic Approach
Authors: Sell Jerzy 
Published: November 2003

AbstractThe distribution pattern of mtDNA haplotypes in distinct populations of the glacial relict crustacean Saduria entomon was examined to assess phylogeographic relationships among them. Populations from the Baltic, the White Sea and the Barents Sea were screened for mtDNA variation using PCR‐based RFLP analysis of a 1150 bp fragment containing part of the CO I and CO II genes. Five mtDNA haplotypes were recorded. An analysis of geographical heterogeneity in haplotype frequency distributions revealed significant differences among populations. The isolated populations of S. entomon have diverged since the retreat of the last glaciation. The geographical pattern of variation is most likely the result of stochastic (founder effect, genetic drift) mechanisms and suggests that the haplotype differentiation observed is probably older than the isolation of the Baltic and Arctic seas.
Size‐Fractionated Phytoplankton and Relationships with Metazooplankton in a Newly Flooded Reservoir
Authors: Tadonléké Rémy D. , Thouvenot A. , Gilbert D. , Sime‐Ngando T. , Debroas D. , Devaux J. 
Published: November 2003

AbstractIn order to yield some insights into the planktonic food web structure of new reservoirs, size‐fractionated biomass and productivity of phytoplankton were examined from 1996 to 1997 (following the 1995 flooding of the Sep Reservoir, Puy‐de‐Dôme, France), in relation to nutrients (P, N) and metazooplankton (Rotifers, Cladocera, Copepods). Autotrophic nanoplankton (ANP, size class 3–45 μm) dominated the phytoplankton biomass (as Chlorophyll a) and production, while autotrophic picoplankton (APP, 0.7–3 μm) exhibited the lowest and relatively constant biomass and production. Cells of the autotrophic microplankton (AMP, >45 μm) were considered inedible for planktonic herbivores. The production‐biomass diagram for the different size classes and the positive correlation between APP production and ANP + AMP production suggested that grazing was potentially more important than nutrients in shaping the phytoplankton size structure. Metazooplankton biomass was low compared to other newly flooded reservoirs or to natural lakes with phytoplankton biomass similar to that of the Sep Reservoir. This resulted in low ratios (metazooplankton to edible phytoplankton) both in terms of production (average 0.43% in 1996 and 0.76% in 1997) and biomass, suggesting that only a small fraction of phytoplankton was directly consumed by metazooplankton. We suggest that the observed low ratios in the Sep Reservoir, reflect possible low metazooplankton inputs in the main influents, changes in hydrologic conditions and a high potential role of microheterotrophs. The latter role was supported by (i) the positive inter‐annual correlation between ciliates and phytoplankton, (ii) the significant and negative correlations between ciliates and metazooplankton, and (iii) the significant and negative correlations between total metazooplankton biomass and total phosphorus (TP), whereas neither TP nor total metazooplankton biomass was correlated with phytoplankton variables.
Strain‐rate effect on the biomechanical response of bovine temporomandibular joint disk under compression
Authors: Tanaka Eiji , del Pozo Rodrigo , Tanaka Masao , Aoyama Junko , Hanaoka Koichi , Nakajima Akira , Inuzuka Shinichi , Tanne Kazuo 
Published: November 2003

AbstractThis study evaluates the effect of strain rate on the biomechanical responses of bovine temporomandibular joint (TMJ) disk under compression. Ten specimens derived from the central region of bovine TMJ disks were used for compression tests. Each specimen was loaded upto 20% of strain with seven different strain rates: 1, 10, 20, 30, 40, 50, and 60%/s. Although the stress–strain curves presented similar patterns for all the specimens, the strain‐rate effect was obvious. The linear modulus by regression fit for the linear part of the curve was significantly larger at 60%/s of strain rate than at the lower strain rates. The “supplemental stress” ratio (SSR) obviously increased with the augmentation of the strain rate. At strain rates of 30–60%/s, the SSR was significantly larger than those at strain rates below 20%/s. These findings indicate that although water easily can move through the TMJ disk at the lower strain rates, the higher strain rates make such movement difficult. It is concluded that the secondary changes of the TMJ disk may be dependent on the pattern and velocity of masticatory mandibular movements directly associated with the dynamic strain rate in the TMJ disk. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 761–765, 2003
Biomimetic surfactant polymers designed for shear‐stable endothelialization on biomaterials
Authors: Sagnella Sharon , Kligman Faina , Marchant Roger E. , Kottke‐Marchant Kandice 
Published: November 2003

AbstractWe have developed a series of “extracellular matrix (ECM)‐like” biomimetic surfactant polymers to improve endothelial cell adhesion and growth on vascular biomaterials. These polymers provide a single‐step procedure for modifying the surface of existing biomaterials and consist of a poly(vinyl amine) (PVAm) backbone with varying ratios of cell‐binding peptide (RGD) to carbohydrate (maltose), ranging from 100% RGD:0% maltose to 50% RGD:50% maltose. Three biomimetic surfaces, as well as a fibronectin (FN)‐coated glass surface were seeded at confluence with human pulmonary artery endothelial cells (HPAECs) and exposed to shear stresses ranging from 0–40.6 dyn/cm2 for periods of 2 h and 6 h. Surfaces were examined for HPAEC coverage and cytoskeletal arrangement as a function of time and shear stress. In general, after 6 h of shear exposure, EC retention on 100% RGD > FN > 75% RGD > 50% RGD. The 100% RGD surface maintained more than 50% of its initial EC monolayer at low to moderate shear stresses whereas all other surfaces dropped to ≈40% or less in the same shear stress range. The most stable surface, 100% RGD, showed a significant increase in cytoskeletal organization at all shear stresses greater than 2.5 dyn/cm2. In contrast, there was no real change in cytoskeletal organization on the FN surface, and there was a decrease on the 75% RGD surface over time. These results indicate that increasing surface peptide density can control EC shear stability. Furthermore, improved shear stability increases with increasing peptide density and is related to the EC's ability to reorganize its cytoskeleton. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 689–701, 2003
Ex ova chick chorioallantoic membrane as a novel model for evaluation of tissue responses to biomaterials and implants
Authors: Klueh Ulrike , Dorsky David I. , Moussy Francis , Kreutzer Don L. 
Published: November 2003

AbstractOne of the major obstacles in developing rationale strategies to control inflammation and fibrosis surrounding implants is the lack of a simple and inexpensive in vivo model to screen tissue reactions to various biomaterials and implants. To begin to fill this gap, we have developed an ex ova model of the chick embryo chorioallantoic membrane (CAM) for testing of tissue reaction to biomaterials and implants. For these studies, we evaluated tissue reactions (inflammation and fibrosis) to two commonly used biomaterials (nylon and silastic) grossly and histologically in the ex ova CAM. Nylon mesh was incorporated within the CAM tissue 4 days postplacement. After 8 days postplacement, the nylon mesh was totally incorporated into the CAM. Histologically, little or no inflammation was seen associated with the incorporated nylon mesh at any time point. In the case of silastic tubing, significant incorporation of the CAM was seen grossly by 1–2 days postplacement. Incorporation of the tubing continued at day 8 postplacement of the silastic tubing, with ingrowth of the CAM into the lumen of the tubing. Histological evaluation of CAMs indicated that no significant tissue reactions (inflammation or fibrosis) occurred in the CAM tissue surrounding the silastic tubing or in the CAM tissue and vasculature that had grown into the silastic tubing. To our knowledge, this report represents the first investigation of the usage of the ex ova CAM model, a shell‐less chick embryo model (ex ova), as an in vivo model to test the tissue reactions to biomaterials and implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 838–843, 2003
The effect of irradiation, annealing temperature, and artificial aging on the oxidation, mechanical properties, and fracture mechanisms of UHMWPE
Authors: Luisetto Yannick , Wesslen Bengt , Maurer Frans , Lidgren Lars 
Published: November 2003

AbstractUHMWPE crosslinked using Gamma radiation is believed to have improved wear properties, and this has been extensively studied during the past 10 years. Mechanical properties, oxidation, and wear properties of UHMWPE materials subjected to various thermal treatments have been investigated immediately after irradiation as well as after several years of aging. Nevertheless, the relationship between all these parameters is not yet fully understood. The aim of this study was to investigate the relationship between the thermal treatments that could be applied to irradiated UHMWPE [lower (γ60) or higher (γ150) than 140°C, the melting temperature of the polymer] and the mechanical properties, the oxidation and the fracture behavior of the material. The effect of artificial aging on these properties was also investigated. This study concludes that immediately after the annealing, the mechanical properties (UTS and ϵ) of the irradiated and annealed material are improved compared with those of nonirradiated material. Although nonirradiated material has higher fracture toughness than irradiated and annealed materials, the materials break according to the same mechanism of fracture. After aging, no changes could be observed in any of the measured properties for nonirradiated material. On the other hand, important changes could be seen in both irradiated and annealed material after aging. Both UTS and ϵ decreased, much more so in the case of γ60. Furthermore, the aging induced a subsurface peak of oxidation in both irradiated and annealed materials, twice as intense for γ60 than for γ150. The mechanism of fracture of these materials changed drastically after aging, probably due to the presence of the oxidation peak, which seems to occur at a location where cracks initiate easily compared with the nonoxidized bulk of the material. In the case of γ60, it seems clear that a correlation between mechanical property, oxidation, and fracture mechanism exists. Such a relationship could not be found for γ150. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 908–917, 2003
Novel method of preparing acellular cardiovascular grafts by decellularization with poly(ethylene glycol)
Authors: Uchimura Eiichiro , Sawa Yoshiki , Taketani Satoshi , Yamanaka Yuka , Hara Masayuki , Matsuda Hikaru , Miyake Jun 
Published: November 2003

AbstractWe have developed a new method of preparing acellular vascular grafts. Cellular components, including cell membranes and proteins in cytosol, were efficiently extracted from the vessels in a concentrated aqueous solution of poly(ethylene glycol), an amphiphilic biocompatible polymer. The residual DNA was digested by deoxyribonuclease I treatment after extraction with poly(ethylene glycol). The two‐step extraction process proved quite effective at removing the cellular components while causing little damage to the extracellular matrices. We did not use any detergent that would damage the extracellular matrices. Therefore, vascular endothelial cells grew well on the acellular vessels after recellularization, promising longi‐patent cardiovascular grafts. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 834–837, 2003
Colonization of organoapatite–titanium mesh by preosteoblastic cells
Authors: Spoerke Erik D. , Stupp Samuel I. 
Published: November 2003

AbstractTitanium (Ti) and its alloys continue to serve as successful implant materials for skeletal repair because of their physical properties and biocompatibility. This study investigates the influence of organoapatite (OA), grown directly onto an L‐shaped Ti mesh, on preosteoblastic cellular colonization. Unseeded mesh samples were placed on subconfluent layers of MC3T3‐E1 murine calvaria cells and cultured for up to 2 weeks. Cells demonstrated accelerated colonization of the three‐dimensional OA–Ti mesh substrates over bare Ti controls. Cells also showed significantly increased proliferation on the OA–Ti mesh over bare Ti controls. Cellular differentiation, measured by alkaline phosphatase and osteocalcin expression, was observed at late stages of the experiment with no notable differences between OA–Ti mesh and bare Ti controls. These results suggest that OA grown onto porous Ti substrates is capable of inducing accelerated colonization of unseeded implant structures by osteogenic cells. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 960–969, 2003
NH3/O2 mixed gas plasmas alter the interaction of blood components with stainless steel
Authors: Chen Meng , Zamora Paul O. , Peña Louis , Som Prantika , Osaki Shigemasa 
Published: November 2003

AbstractStainless steel treated with a mixed gas plasma of NH3 plus O2 had chemical and biologic characteristics distinct from untreated stainless steel or stainless steel treated with NH3 or O2 plasmas used separately. NH3/O2 plasmas deposited nitrogen as both −CN (organic) and −NO (nitrate, nitrite)—materials not found on untreated stainless steel—and the contact angle changed from 44° to 23°. Treatment of stainless steel (and titanium) resulted in surfaces with enhanced resistance to platelet and leukocyte attachment. A gas plasma of N2O/O2 also was found to reduce platelet and leukocyte attachment, suggesting that these properties may be common to surfaces coated with oxynitrites (nitrides). Upon subcutaneous implantation, no inflammation, hemolysis, or untoward thrombosis was noted in the tissue surrounding the wafers treated with the NH3/O2 plasmas, although the cellular density was considerably reduced by 2 weeks after implant. Collectively, the results suggest that NH3/O2 plasmas impart a unique character to stainless steel that may be useful in the construction of medical devices. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 994–1000, 2003
Effect of hydrogen peroxide on titanium surfaces: In situ imaging and step‐polarization impedance spectroscopy of commercially pure titanium and titanium, 6‐aluminum, 4‐vanadium
Authors: Bearinger Jane P. , Orme Christine A. , Gilbert Jeremy L. 
Published: November 2003

AbstractTo analyze titanium's response to representative surgical wound environments, a study was conducted on commercially pure titanium (CPTi) and titanium, 6‐aluminum, 4‐vanadium (Ti‐6Al‐4V) exposed to phosphate‐buffered saline (PBS) with 30 mM of hydrogen peroxide (H2O2) added. The study was characterized by simultaneous electrochemical atomic force microscopy (EC AFM) and step‐polarization impedance spectroscopy (SPIS). Surfaces were covered with protective oxide domes that indicated topography changes with potential and time of immersion. Less oxide dome coarsening was noted on surfaces treated with PBS containing H2O2 than on surfaces exposed to pure PBS. Electrical data deduced from current transients collected while stepping voltage between 0 V and 1 V indicated that charge transfer in hydrogen peroxide solutions was an order of magnitude larger than it was in pure PBS. Oxide (early) resistances of CPTi samples were higher than were Ti‐6Al‐4V oxide resistances in both types of solutions, but CPTi oxide resistance was lower in the hydrogen peroxide solution compared to pure PBS. Capacitance data suggest that CPTi oxide films thicken in hydrogen peroxide solution more than they do in pure PBS. Differences in electrical properties between CPTi and Ti‐6Al‐4V surfaces suggest that CPTi, but not Ti‐6Al‐4V, has catalytic activity on H2O2 and that the catalytic activity of CPTi oxide affects its ability to grow TiO2. Differences in electrical properties are related to catalytic and oxidative mechanisms that take place directly on the titanium oxide surface and in wound environments. The study provides a foundation and theoretic basis for the porous oxide model on commercially pure titanium exposed to hydrogen peroxide. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 702–712, 2003
In vivo behavior of poly(1,3‐trimethylene carbonate) and copolymers of 1,3‐trimethylene carbonate with D,L‐lactide or ϵ‐caprolactone: Degradation and tissue response
Authors: Pêgo A. P. , Van Luyn M. J. A. , Brouwer L. A. , van Wachem P. B. , Poot A. A. , Grijpma D. W. , Feijen J. 
Published: November 2003

AbstractThe degradation and the tissue response evoked by poly(1,3‐trimethylene carbonate) [poly(TMC)] and copolymers of TMC with either 52 mol % D,L‐lactide (DLLA) or 89 mol % ϵ‐caprolactone (CL) were evaluated in vivo by subcutaneous implantation of polymer films in rats for periods up to one year. Poly(TMC) specimens were extensively degraded after 3 weeks and, as confirmed by histology, totally resorbed in less than a year. A fast linear decrease in thickness and mass without a change in molecular weight was observed. Initially an acute sterile inflammatory tissue reaction, caused by the implantation procedure, was observed, followed by a mild macrophage‐mediated foreign body reaction that lasted during the resorption period of the polymer. It is concluded that in vivo, poly(TMC) is degraded via surface erosion involving cellular‐mediated processes. The degradation of the copolymers was slower than that of poly(TMC), taking place via autocatalyzed bulk hydrolysis, preferentially of ester bonds. The TMC‐DLLA copolymer degraded 20 times faster than the TMC‐CL one. In both cases, the tissue reaction upon implantation resembled a sterile inflammatory reaction followed by a foreign body reaction that led to the polymer encapsulation. Significant mass loss was only observed for the TMC‐DLLA copolymer, which underwent 96% mass loss in 1 year. When extensive mass loss started, a mild‐to‐moderate secondary foreign body reaction, related to clearance of the polymer fragments, was triggered. The results presented in this study demonstrate that poly(TMC) and both TMC copolymers are biodegradable and biocompatible materials, making these polymers attractive for the preparation of short‐ and long‐term degradable devices for soft tissue engineering. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1044–1054, 2003
Bonding strength of the apatite layer formed on glass‐ceramic apatite‐wollastonite–polyethylene composites
Authors: Juhasz J. A. , Best S. M. , Kawashita M. , Miyata N. , Kokubo T. , Nakamura T. , Bonfield W. 
Published: November 2003

AbstractBioactive glass‐ceramic apatite‐wollastonite (A‐W) has been incorporated into polyethylene in particulate form to create new bioactive composites for potential maxillofacial applications. The effects of varying the volume fraction of glass‐ceramic A‐W filler and the glass‐ceramic A‐W particle size were investigated by measuring the bonding strength of the bonelike apatite layer formed on the surface of glass‐ceramic A‐W–polyethylene composites. The bonding strength was evaluated via a modified ASTM C‐333 standard in which a tensile stress was applied to the substrate and the strength of the bioactive layer was compared with that formed on commercially available hydroxyapatite–polyethylene composite samples, HAPEX™. The composites demonstrated greater bonding strength with increased filler content and reduced filler particle size (maximum 6.9 ± 0.5 MPa) and a marginally greater bonding strength as compared with HAPEX™ (2.8 ± 0.5 MPa), when glass‐ceramic A‐W–polyethylene composite samples with the same filler content were tested. The higher bonding strength of the apatite layer formed on the A‐W–polyethylene composite samples suggests that, in addition to maxillofacial applications, these composites might also be utilized in applications involving higher levels of load bearing. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 952–959, 2003