bluuebunny/crossref_metadata_2025_split huggingface dataset:
Introduction of gelatin microspheres into an injectable calcium phosphate cement
Authors: Habraken W. J. E. M. , de Jonge L. T. , Wolke J. G. C. , Yubao L. , Mikos A. G. , Jansen J. A. 
Published: January 2008

AbstractFor tissue engineered bone constructs, calcium phosphate cement (CPC) has a high potential as scaffold material because of its biocompatibility and osteoconductivity. However, in vivo resorption and tissue ingrowth is slow. To address these issues, microspheres can be incorporated into the cement, which will create macroporosity after in situ degradation. The goal of this study was to investigate the handling properties and degradation characteristics of CPC containing gelatin microspheres. Setting time and injectability were determined and an in vitro degradation study was performed. Samples were assayed on mass, compression strength, E‐modulus, and morphology. A supplementary degradation test with gelatin microspheres was performed to investigate the influence of physical conditions inside the cement on microsphere stability. The gelatin microsphere CPCs were easy to inject and showed initial setting times of less than 3 min. After 12‐weeks in vitro degradation no increase in macroporosity was observed, which was supported by the small mass loss and stabilizing mechanical strength. Even a clear densification of the composite was observed. Explanations for the lack of macroporosity were recrystallization of the cement onto or inside the gelatin spheres and a delayed degradation of gelatin microspheres inside the scaffold. The supplementary degradation test showed that the pH is a factor in the delayed gelatin microsphere degradation. Also differences in degradation rate between types of gelatin were observed. Overall, the introduction of gelatin microspheres into CPC renders composites with good handling properties, though the degradation characteristics should be further investigated to generate a macroporous scaffold. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Through‐thickness plasma modification of biodegradable and nonbiodegradable porous polymer constructs
Authors: Safinia Laleh , Wilson Karen , Mantalaris Athanasios , Bismarck Alexander 
Published: January 2008

AbstractPure poly(lactide‐co‐glycolide) and polystyrene surfaces are not very suitable to support cell adhesion/spreading owing to their hydrophobic nature and low surface energy. The interior surfaces of large porous 3D scaffolds were modified and activated using radio‐frequency, low‐pressure air plasma. An increase in the wettability of the surface was observed after exposure to air plasma, as indicated by the decrease in the contact angles of the wet porous system. The surface composition of the plasma‐treated polymers was studied using X‐ray photoelectron spectroscopy. pH‐dependent zeta‐potential measurements confirm the presence of an increased number of functional groups. However, the plasma‐treated surfaces have a less acidic character than the original polymer surfaces as seen by a shift in their isoelectric point. Zeta‐potential, as well as contact angle measurements, on 3D scaffolds confirm that plasma treatment is a useful tool to modify the surface properties throughout the interior of large scaffolds. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Bone reaction to nano hydroxyapatite modified titanium implants placed in a gap‐healing model
Authors: Meirelles Luiz , Albrektsson Tomas , Kjellin Per , Arvidsson Anna , Franke‐Stenport Victoria , Andersson Martin , Currie Fredrik , Wennerberg Ann 
Published: January 2008

AbstractNanohydroxyapatite materials show similar chemistry to the bone apatite and depending on the underlying topography and the method of preparation, the nanohydroxyapatite may simulate the specific arrangement of the crystals in bone. Hydroxyapatite (HA) and other CaP materials have been indicated in cases in which the optimal surgical fit is not achievable during surgery, and the HA surface properties may enhance bone filling of the defect area. In this study, very smooth electropolished titanium implants were used as substrata for nano‐HA surface modification and as control. One of each implant (control and nano HA) was placed in the rabbit tibia in a surgical site 0.7 mm wider than the implant diameter, resulting in a gap of 0.35 mm on each implant side. Implant stability was ensured by a fixating plate fastened with two side screws. Topographical evaluation performed with an optical interferometer revealed the absence of microstructures on both implants and higher resolution evaluation with AFM showed similar nanoroughness parameters. Surface pores detected on the AFM measurements had similar diameter, depth, and surface porosity (%). Histological evaluation demonstrated similar bone formation for the nano HA and electropolished implants after 4 weeks of healing. These results do not support that nano‐HA chemistry and nanotopography will enhance bone formation when placed in a gap‐healing model. The very smooth surface may have prevented optimal activity of the material and future studies may evaluate the synergic effects of the surface chemistry, micro, and nanotopography, establishing the optimal parameters for each of them. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008
In situ formation of hydrogels as vitreous substitutes: Viscoelastic comparison to porcine vitreous
Authors: Swindle Katelyn E. , Hamilton Paul D. , Ravi Nathan 
Published: January 2008

AbstractThe human vitreous is a gelatinous substance predominantly composed of water (97–99%). Vitreous substitutes are needed for treatment of retinal detachments by reapproximating the retina to the back of the eye, or during vitrectomies for maintenance of ocular volume. None of the current substitutes can be used long‐term due to their short retention time, toxicity, or complications such as glaucoma or cataracts. In addition, all of the current compounds have a specific gravity less than water and so are not appropriate for inferior retinal detachments. The viscoelastic properties of the porcine vitreous were analyzed to develop a model for ideal substitutes. Synthetic polymers that form hydrogels in situ were researched for the development of artificial vitreous. In this study, the physical, mechanical, and optical properties of four self‐gelling polyacrylamide copolymeric hydrogels were determined and compared with those of the porcine vitreous. The 2% formulation of high crosslink density, hydrophobically modified hydrogel most closely mimicked the porcine vitreous. The viscoelastic properties of hydrogels capable of being formed in situ were compared to those of the porcine vitreous to determine their efficacy as vitreous substitutes. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Cell migration by a FRS2‐adaptor dependent membrane relocation of ret receptors
Authors: Lundgren T. Kalle , Stenqvist Anna , Scott Rizaldy P. , Pawson Tony , Ernfors Patrik 
Published: January 2008

AbstractDuring development neural progenitor cells migrate with extraordinary precision to inhabit tissues and organs far from their initial position. Little is known about the cellular basis for directional guidance by tyrosine kinase receptors (RTKs). RET is a RTK with important functions in guiding the migration of neuronal cells, and RET dysregulation leads to clinical disease such as agangliosis of the colon. We show here that RET migration in neuroepitheliomal and non‐neuronal cells is elicited by the activation of specific signaling pathways initiated by the competitive recruitment of the FRS2 adaptor molecule to tyrosine 1062 (Y1062) in RET. FRS2 selectively recruited RET to focal complexes and led to activation of SRC family kinases and focal adhesion kinase (FAK). Activation of SRC depended on its direct interaction with RET at a different intracellular tyrosine (Y981) and activation of molecular signaling from these two separate sites in concert regulated migration. Our data suggest that an important function for FRS2 is to concentrate RET in membrane foci, leading to an engagement of specific signaling complexes localized in these membrane domains. J. Cell. Biochem. 104: 879–894, 2008. © 2008 Wiley‐Liss, Inc.
Sanguinarine‐induced apoptosis: Generation of ROS, down‐regulation of Bcl‐2, c‐FLIP, and synergy with TRAIL
Authors: Kim Shin , Lee Tae‐Jin , Leem Jaechan , Choi Kyeong Sook , Park Jong‐Wook , Kwon Taeg Kyu 
Published: January 2008

AbstractSanguinarine is a benzophenanthridine alkaloid derived from the root of Sanguinaria canadensis and other poppy‐fumaria species, possessing potent antibacterial, antifungal, and anti‐inflammatory activities. In this study, we investigated the underling mechanisms by which sanguinarine induce apoptosis in human breast cancer MDA‐231 cells. Treatment of MDA‐231 cells with sanguinarine induced remarkable apoptosis accompanying the generation of ROS. Consistently, sanguinarine‐induced apoptosis was mediated by the increased reproductive cell death. Pretreatment with NAC or GSH attenuated sanguinarine‐induced apoptosis, suggesting the involvement of ROS in this cell death. During sanguinarin‐induced apoptosis, protein levels of pro‐caspase‐3, Bcl‐2, cIAP2, XIAP, and c‐FLIPs were reduced. Sanguinarine‐mediated apoptosis was substantially blocked by ectopic expression of Bcl‐2 and cFLIPs. Additionally, we found that sub‐lethal doses of sanguinarine remarkably sensitized breast cancer cells to TRAIL‐mediated apoptosis, but the cell death induced by sanguinarine and TRAIL in combination was not blocked by overexpression of Bcl‐2 or Akt. Therefore, combinatory treatment of sanguinarine and TRAIL may overcome the resistance of breast cancer cells due to overexpression of Akt or Bcl‐2. J. Cell. Biochem. 104: 895–907, 2008. © 2008 Wiley‐Liss, Inc.
Reishi immuno‐modulation protein induces interleukin‐2 expression via protein kinase‐dependent signaling pathways within human T cells
Authors: Hsu Hsien‐Yeh , Hua Kuo‐Feng , Wu Wei‐Chi , Hsu Jason , Weng Shih‐Ting , Lin Tsai‐Leng , Liu Chun‐Yi , Hseu Ruey‐Shyang , Huang Ching‐Tsan 
Published: January 2008

AbstractGanoderma lucidum, a medicinal fungus is thought to possess and enhance a variety of human immune functions. An immuno‐modulatory protein, Ling Zhi‐8 (LZ‐8) isolated from G. lucidum exhibited potent mitogenic effects upon human peripheral blood lymphocytes (PBL). However, LZ‐8‐mediated signal transduction in the regulation of interleukin‐2 (IL‐2) gene expression within human T cells is largely unknown. Here we cloned the LZ‐8 gene of G. lucidum, and expressed the recombinant LZ‐8 protein (rLZ‐8) by means of a yeast Pichia pastoris protein expression system. We found that rLZ‐8 induces IL‐2 gene expression via the Src‐family protein tyrosine kinase (PTK), via reactive oxygen species (ROS), and differential protein kinase‐dependent pathways within human primary T cells and cultured Jurkat T cells. In essence, we have established the nature of the rLZ‐8‐mediated signal‐transduction pathways, such as PTK/protein kinase C (PKC)/ROS, PTK/PLC/PKCalpha/ERK1/2, and PTK/PLC/PKCalpha/p38 pathways in the regulation of IL‐2 gene expression within human T cells. Our current results of analyzing rLZ‐8‐mediated signal transduction in T cells might provide a potential application for rLZ‐8 as a pharmacological immune‐modulating agent. J. Cell. Physiol. 215: 15–26, 2008. © 2008 Wiley‐Liss, Inc.
Wheat germ agglutinin stains dispersed post‐golgi vesicles after treatment with the cytokinesis inhibitor psychosine
Authors: Kanazawa Takayuki , Takematsu Hiromu , Yamamoto Akitsugu , Yamamoto Harumi , Kozutsumi Yasunori 
Published: January 2008

AbstractThe galactosylsphingosine psychosine (Psy) is one of the sphingolipids and induce the formation of multinuclear cells in several cell lines by inhibiting cytokinesis. In the present report, we show that intracellular organelles, including wheat germ agglutinin (WGA)‐positive vesicles and early endosomes, are selectively dispersed by Psy. WGA is a conventional Golgi marker and WGA‐positive vesicles appeared to co‐localize with the Golgi apparatus in untreated cells. Psy treatment induced the dispersal of WGA‐positive vesicles without affecting the structure of the Golgi apparatus, resulting in discrimination of WGA‐positive vesicles from the Golgi apparatus. In sharp contrast to this effect of Psy, WGA‐positive vesicles were not affected by brefeldin A treatment, which induced the disappearance of the Golgi apparatus. Immunostaining with anti‐TGN46 antibodies revealed that a large portion of the WGA‐positive vesicles were derived from the trans‐Golgi network. Notably, the dispersed WGA‐positive vesicles did not stain with anti‐syntaxin 6, another marker of the trans‐Golgi network. During cytokinesis, WGA‐positive vesicles in the cytoplasm decreased, and WGA staining accumulated at the cleavage furrow, which was apparently inhibited by the presence of Psy. These data suggest that the transport of WGA‐positive vesicles to the cleavage furrow is associated with the progression of cytokinesis. J. Cell. Physiol. 215: 517–525, 2008. © 2008 Wiley‐Liss, Inc.
Mechanism of electron transfer reaction of ternary nitrilotriacetatocobalt(II) complexes involving succinate and malonate as secondary ligands
Authors: Ewais Hassan A. 
Published: January 2008

AbstractThe mechanism of oxidation of ternary complexes, [CoII(nta)(S)(H2O)2]3− and [CoII(nta)(M)(H2O)]3− (nta = nitrilotriacetate acid, S = succinate dianion, and M = malonate dianion), by periodate in aqueous medium has been studied spectrophotometrically over the (20.0–40.0) ± 0.1°C range. The reaction is first order with respect to both [IO4−] and the complex, and the rate decreases over the [H+] range (2.69–56.20) × 10−6 mol dm−3 in both cases. The experimental rate law is consistent with a mechanism in which both the hydroxy complexes [CoII(nta)(S)(H2O)(OH)]4− and [CoII(nta)(M)(OH)]4− are significantly more reactive than their conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of the [CoII(nta)(S)(H2O)2]3−, k1 (3.60 × 10−3 s−1), is greater than the value of k6 (1.54 × 10−3 s−1) for the oxidation of [CoII(nta)(M)(H2O)]3− at 30.0 ± 0.1°C and I = 0.20 mol dm−3. The thermodynamic activation parameters have been calculated. It is assumed that electron transfer takes place via an inner‐sphere mechanism. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 103–113, 2008
Ru(III)‐catalyzed oxidation of cysteine hydrochloride by methylene blue in acidic medium; synergetic effect of Cu(II): A kinetic study
Authors: Chaturvedi R. , Mishra K. K. 
Published: January 2008

AbstractCysteine hydrochloride and methylene blue (MB) interact in a molar ratio of 2:1 in acidic medium forming cystine and dihydromethylene blue, and the reaction is catalyzed by Ru(III). At low concentrations (ca. 2.0 × 10−8 M), Cu(II) does not catalyze the reaction significantly but at this concentration level the catalytic activity of Ru(III) is found to be augmented by the addition of Cu(II) and the kinetics of Ru(III)‐catalyzed reaction has been studied in the absence and in the presence of externally added Cu(II). The reaction follows a half‐order kinetics in MB that increases to ¾ on increasing [MB] beyond 1.5 × 10−5 M in the Ru‐catalyzed reaction. In the Ru–Cu catalyzed reaction; the order in MB is ¾ even at lower concentrations of MB. The order in cysteine is unity. The rate decreases on increasing [MB] in both cases but attains a limiting value at higher concentrations of MB (ca. >2.0 × 10−5 M) in the presence of Ru(III) alone. The rate increases on increasing [H+] and in Ru‐catalyzed reaction, an optimum is noticed. The rate increases linearly with increasing [Ru(III)], but equilibration of the catalyst with other ingredients of the reaction system decreases the rate. The FTIR spectra of the reaction system exhibit time‐dependent changes in the stretching as well as bending modes of –SH group. The synergetic effect of Cu(II) has been attributed to its ligation with cysteine and its subsequent interaction with Ru(II) produced in situ in the system. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 145–150, 2008
Peculiar kinetics of the complex formation in the iron(III)–sulfate system
Authors: Kormányos Balázs , Peintler Gábor , Nagy Andrea , Nagypál István 
Published: January 2008

AbstractThe results of comprehensive equilibrium and kinetic studies of the iron(III)–sulfate system in aqueous solutions at I = 1.0 M (NaClO4), in the concentration ranges of T = 0.15–0.3 mM, and at pH 0.7–2.5 are presented. The iron(III)–containing species detected are FeOH2+ (=FeH−1), (FeOH) (=Fe2H−2), FeSO, and Fe(SO4) with formation constants of log β = −2.84, log β = −2.88, log β = 2.32, and log β = 3.83. The formation rate constants of the stepwise formation of the sulfate complexes are k1a = 4.4 × 103 M−1 s−1 for the \documentclass{article}\pagestyle{empty}\begin{document}${\rm Fe}^{3+} + {\rm SO}_4^{2-}\,\stackrel{k_{1a}}{\rightleftharpoons}\, {\rm FeSO}_4^+$\end{document} step and k2 = 1.1 × 103 M−1 s−1 for the \documentclass{article}\pagestyle{empty}\begin{document}${\rm FeSO}_4^+ + {\rm SO}_4^{2-} \stackrel{k_2}{\rightleftharpoons}\, {\rm Fe}({\rm SO}_4)_2^-$\end{document} step. The mono‐sulfate complex is also formed in the \documentclass{article}\pagestyle{empty}\begin{document}${\rm Fe}({\rm OH})^{2+} + {\rm SO}_4^{2-} \stackrel{k_{1b}}{\longrightarrow} {\rm FeSO}_4^+$\end{document} reaction with the k1b = 2.7 × 105 M−1 s−1 rate constant. The most surprising result is, however, that the 2 FeSO⇌ Fe3+ + Fe(SO4) equilibrium is established well before the system as a whole reaches its equilibrium state, and the main path of the formation of Fe(SO4) is the above fast (on the stopped flow scale) equilibrium process. The use and advantages of our recently elaborated programs for the evaluation of equilibrium and kinetic experiments are briefly outlined. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 114–124, 2008
Analysis and computational study of several integer programming formulations for minimum‐energy multicasting in wireless ad hoc networks
Authors: Bauer Joanna , Haugland Dag , Yuan Di 
Published: January 2008

AbstractA multicast session in a wireless ad hoc network concerns routing messages from a source to a set of destination devices. Transmitting messages consumes energy at the source and intermediate devices of the session. Since a battery is the only energy source in many applications of wireless ad hoc networks, energy efficiency is an important performance measure of multicasting. In this paper, we present and analyze integer programming models for the problem of minimizing the total energy required by multicasting. We start from a straightforward multicommodity flow model, which is strengthened by a more efficient representation of transmission power. Further strengthening is accomplished by lifting the capacity constraints of the model. We then present cut‐based models for the problem, and prove, from a bounding standpoint, the equivalence in strength between these models and their flow‐based counterparts. By expanding the underlying graph, we show that the problem can be transformed into finding a minimum Steiner arborescence. The expanded graph arises also in the separation procedure for solving one of the cut‐based models. In addition to a theoretical analysis of the relation between various models, we perform extensive computational experiments to study the numerical strengths of these models and their efficiency in solving the problem. © 2008 Wiley Periodicals, Inc. NETWORKS, 2008
Exact algorithms for the master ring problem
Authors: Shachnai Hadas , Zhang Lisa , Matsui Tomomi 
Published: January 2008

AbstractWe consider the master ring problem (MRP) which often arises in optical network design. Given a network which consists of a collection of interconnected rings R1,…,RK, with n1,…,nK distinct nodes, respectively, we need to find an ordering of the nodes in the network that respects the ordering of every individual ring, if one exists. We show that MRP is NP‐complete, and therefore, it is unlikely to be solvable by a polynomial time algorithm. Our main result is an algorithm which solves MRP in $ Q \cdot \Pi_{k=1}^{K} (n_{k}/\sqrt{2}) $ steps, for some polynomial Q, as the nk values become large. For the ring clearance problem, a special case of practical interest, our algorithm achieves this running time for rings of any size nk ≥ 2. This yields the first nontrivial improvement, by factor of $ (2\sqrt{2})^{K} \approx (2.82)^{K} $, over the running time of the naive algorithm, which exhaustively enumerates all $ \Pi_{k=1}^{K} (2n_{k}) $ possible solutions. © 2008 Wiley Periodicals, Inc. NETWORKS, 2008
On the diameter of the generalized undirected de Bruijn graphsUGB(n,m),n2<m≤n3
Authors: Kuo Jyhmin , Fu Hung‐Lin 
Published: January 2008

AbstractThe generalized de Bruijn digraphGB(n,m) is the digraph (V,A) whereV= {0, 1,…,m− 1} and (i,j) ∈Aif and only ifj≡in+α(modm) for someα∈ {0, 1, 2,…,n− 1}. By replacing each arc ofGB(n,m) with an undirected edge and eliminating loops and multi‐edges, we obtain the generalized undirected de Bruijn graphUGB(n,m). In this article, we prove that when 2n2≤m≤n3the diameter ofUGB(n,m) is equal to 3. We also show that for pairs (n,m) wheren2<m< 2n2the diameter ofUGB(n,m) can be 2 or 3. © 2008 Wiley Periodicals, Inc. NETWORKS, 2008
Reliability of interconnection networks modeled by Cartesian product digraphs
Authors: Yang Chao , Xu Jun‐Ming 
Published: January 2008

AbstractWe determine that the connectivity and the edge‐connectivity of the Cartesian product G1 × G2 of two strongly connected and finite digraphs G1 and G2 are equal to min{n1κ2,n2κ1,δ + δ, δ + δ} and min{n1λ2,n2λ1, δ + δ, δ + δ}, respectively, where ni, κi, λi, δ, δ are the order, the connectivity, the edge‐connectivity, the minimum out‐degree and the minimum in‐degree of Gi, respectively, for i = 1, 2. © 2008 Wiley Periodicals, Inc. NETWORKS, 2008
Valid cycles: A source of infeasibility in open shortest path first routing
Authors: Broström Peter , Holmberg Kaj 
Published: January 2008

AbstractMany telecommunication networks use the open shortest path first (OSPF) protocol for the routing of traffic. In such networks, each router sends the traffic on the shortest paths to the destination, with respect to the link weights assigned. An interesting question is whether or not a set of desired routing patterns can be obtained in an OSPF network by assigning appropriate weights. If not, we wish to find the source of the infeasibility. We study these issues by formulating a mathematical model and investigating its feasibility. A certain structure, called valid cycle, is found to be present in most infeasible instances. This yields new necessary conditions, stronger than those previously known, for the existence of weights yielding a set of given desired shortest path graphs. A valid cycle indicates which parts of the routing patterns are in conflict and can be used for changing the routing patterns to make the problem feasible. A polynomial algorithm for finding valid cycles is presented, the method is illustrated by a numerical example, and computational tests are reported. © 2008 Wiley Periodicals, Inc. NETWORKS, 2008