bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of CD44 deficiency on in vitro and in vivo osteoclast formation
Authors: de Vries Teun J. , Schoenmaker Ton , Beertsen Wouter , van der Neut Ronald , Everts Vincent 
Published: December 2004

AbstractIn vitro studies have shown that CD44 is involved in the fusion process of osteoclast precursor cells. Yet, in vivo studies do not support this, since an osteopetrotic phenotype has not been described for CD44 knock‐out (CD44 k.o.) mice. This discrepancy may suggest that the role of CD44 in fusion may depend on the microenvironment of osteoclast formation. We investigated osteoclast formation of CD44 k.o. and wild‐type mice under three conditions: in vitro, both on plastic and on bone and in vivo by analyzing osteoclast number, and size in long bones from wild‐type and CD44 k.o. mice. Bone marrow cells from wild‐type and CD44 k.o. mice were analyzed for their capacity to form osteoclasts on plastic and on bone in the presence of macrophage colony stimulating factor (M‐CSF) and receptor activator of NF‐kB ligand (RANKL). On plastic, the number of multinucleated tartrate resistant acid phosphatase (TRAP) positive cells in CD44 k.o. cultures was twofold higher than in wild‐type cultures. On bone, however, equal numbers of osteoclasts were formed. Interestingly, the total number of osteoclasts formed on bone proved to be higher than on plastic for both genotypes, strongly suggesting that osteoclastogenesis was stimulated by the bone surface, and that CD44 is not required for osteoclast formation on bone. Functional analyses showed that bone resorption was similar for both genotypes. We further studied the osteoclastogenic potential of wild‐type bone marrow cells in the presence of CD44 blocking antibodies. Osteoclastogenesis was not affected by these antibodies, a further indication that CD44 is not required for the formation of multinucleated cells. Finally, we analyzed the in vivo formation of osteoclasts by analyzing long bones from wild‐type and CD44 k.o. mice. Morphometric analysis revealed no difference in osteoclast number, nor in number of nuclei per osteoclasts or in osteoclast size. Our in vitro experiments on plastic showed an enhanced formation of osteoclasts in the absence of CD44, thus suggesting that CD44 has an inhibitory effect on osteoclastogenesis. However, when osteoclasts were generated on bone, no differences in number of multinucleated cells nor in bone resorption were seen. These observations are in agreement with in vivo osteoclast characteristics, where no differences between wild‐type and CD44 k.o. bones were encountered. Therefore, the modulating role of CD44 in osteoclast formation appears to depend on the microenvironment. J. Cell. Biochem. 94: 954–966, 2005. © 2004 Wiley‐Liss, Inc.
Thermotolerance of pulp cells and phagocytosis of apoptotic pulp cells by surviving pulp cells following heat stress
Authors: Kitamura Chiaki , Nishihara Tatsuji , Ueno Yoshiko , Nagayoshi Masato , Kasugai Shohei , Terashita Masamichi 
Published: December 2004

AbstractApoptosis is known to be associated with wound healing and regeneration of dental pulp. We examined the effects of heat stress on clonal dental pulp cell line (RPC‐C2A cells) to clarify the pulp wound healing process. RPC‐C2A cells were exposed to heat stress at 43°C for 45 min. After several time intervals, the inhibition of cell proliferation and apoptosis induction were analyzed by cell viability assay, DNA gel electrophoresis, nuclear staining, and terminal deoxynucleotidyl transferase mediated labeling assay. RPC‐C2A cells showed the thermotolerance following heat stress. We found that apoptosis was induced in some RPC‐C2A cells, whereas others remained alive, and observed the engulfment of apoptotic cells by scavenger‐like RPC‐C2A cells following heat stress. We also analyzed the phagocytotic activity of RPC‐C2A cells and found that they had an ability to engulf apoptotic RPC‐C2A cells, which was stimulated by heat stress. These results suggest that heat stress induces apoptosis of RPC‐C2A cells, which are phagocytosed by the surviving RPC‐C2A cells. © 2004 Wiley‐Liss, Inc.
Differentiation of HL‐60 cells to granulocytes involves regulation of select diacylglycerol kinases (DGKs)
Authors: Batista Eraldo L. , Warbington Martha , Badwey John A. , Van Dyke Thomas E. 
Published: December 2004

AbstractDiacylglycerol Kinases (DGKs) are a family of enzymes that regulate the levels of different pools of diacylglycerol (DAG), affecting DAG‐mediated signal transduction. Since DAG is known to play several important regulatory roles in granulocyte physiology, we investigated the expression pattern of DGK isoforms throughout differentiation of HL‐60 cells to granulocytes. HL‐60 cells were incubated with 1.25% dimethyl‐sulfoxide (DMSO) to initiate differentiation and total RNA isolated at different time points. DGK expression was assessed through Northern blot, end‐point PCR, and real‐time PCR. The non‐selective inhibitors R59022 and R59949 were used to block DGK at different time points throughout differentiation. CD11b and GPI‐80, reactive oxygen species (ROS) generation, changes in the cell cycle, and apoptosis were used as markers of differentiation. Of the nine isoforms of DGK evaluated (α, δ, ε, γ, ζ, β, θ, ι, η), only five (α, δ, ε, γ, and ζ) were expressed in HL‐60 cells. DGKα was virtually absent in non‐differentiated cells, but was markedly upregulated throughout differentiation. The other isoforms (δ, ε, γ, and ζ) were expressed in undifferentiated HL‐60 cells but were substantially decreased throughout differentiation. Non‐selective blocking of DGK with R59022 and R59949 led to acceleration of differentiation, reducing the time necessary to observe upregulation of CD11b, GPI‐80 and generation of ROS by 50%. Likewise, the cell cycle was disrupted when DGK isoforms were inhibited. These results provide evidence that DGK levels are dynamically regulated throughout differentiation and that expression of DGKs play an important regulatory function during the differentiation of neutrophils. © 2004 Wiley‐Liss, Inc.
Creatine enhances survival of glutamate‐treated neuronal/glial cells, modulates Ras/NF‐κB signaling, and increases the generation of reactive oxygen species
Authors: Juravleva Elena , Barbakadze Tamar , Mikeladze David , Kekelidze Téa 
Published: December 2004

AbstractThe protective effects of creatine against glutamate cytotoxicity have been demonstrated in neuronal cells and animal models of neurodegenerative diseases. The mechanisms underlying creatine neuroprotection against glutamate‐induced cell death are understood poorly. For the first time, we demonstrate a correlation between the protective effect of creatine and the modulation of Ras‐mediated redox‐dependent signaling pathways, which involve nuclear factor κB (NF‐κB) and reactive oxygen species (ROS). In primary cerebrocortical cultures of mixed neurons and glia, creatine significantly reduced glutamate‐induced cell death. The increase in cell survival was accompanied by increased generation of oxygen radicals and decreased levels of farnesylated Ras and IκB, an inhibitor of NF‐κB. Non‐farnesylated Ras and ROS‐dependent activation of NF‐κB have been shown to promote neuronal survival. Our data suggest that creatine may enhance survival signaling via activation of the Ras/NF‐κB system. Possible mechanisms underlying the protective effect of creatine are discussed, including normalization of cellular GTP levels. © 2004 Wiley‐Liss, Inc.
Activity of the lactate–alanine shuttle is independent of glutamate–glutamine cycle activity in cerebellar neuronal–astrocytic cultures
Authors: Bak Lasse K. , Sickmann Helle M. , Schousboe Arne , Waagepetersen Helle S. 
Published: December 2004

AbstractThe glutamate–glutamine cycle describes the neuronal release of glutamate into the synaptic cleft, astrocytic uptake, and conversion into glutamine, followed by release for use as a neuronal glutamate precursor. This only explains the fate of the carbon atoms, however, and not that of the ammonia. Recently, a role for alanine has been proposed in transfer of ammonia between glutamatergic neurons and astrocytes, denoted the lactate–alanine shuttle (Waagepetersen et al. [ 2000] J. Neurochem. 75:471–479). The role of alanine in this context has been studied further using cerebellar neuronal cultures and corresponding neuronal–astrocytic cocultures. A superfusion paradigm was used to induce repetitively vesicular glutamate release by N‐methyl‐D‐aspartate (NMDA) in the neurons, allowing the relative activity dependency of the lactate–alanine shuttle to be assessed. [15N]Alanine (0.2 mM), [2‐15N]/[5‐15N]glutamine (0.25 mM), and [15N]ammonia (0.3 mM) were used as precursors and cell extracts were analyzed by mass spectrometry. Labeling from [15N]alanine in glutamine, aspartate, and glutamate in cerebellar cocultures was independent of depolarization of the neurons. Employing glutamine with the amino group labeled ([2‐15N]glutamine) as the precursor, an activity‐dependent increase in the labeling of both glutamate and aspartate (but not alanine) was observed in the cerebellar neurons. When the amide group of glutamine was labeled ([5‐15N]glutamine), no labeling could be detected in the analyzed metabolites. Altogether, the results of this study support the existence of the lactate–alanine shuttle and the associated glutamate–glutamine cycle. No direct coupling of the two shuttles was observed, however, and only the glutamate–glutamine cycle seemed activity dependent. © 2004 Wiley‐Liss, Inc.
Glutamate‐mediated influx of extracellular Ca2+ is coupled with reactive oxygen species generation in cultured hippocampal neurons but not in astrocytes
Authors: Kahlert Stefan , Zündorf Gregor , Reiser Georg 
Published: December 2004

AbstractGeneration of reactive oxygen species (ROS) in brain tissue leads to neurodegeneration. The major source of ROS is the mitochondrial respiratory chain. We studied regulation of Ca2+ level, mitochondrial potential, and ROS generation in defined mixed hippocampal cell cultures exposed to glutamate (100 μM). Recordings were made from individually identified astrocytes and neurons to compare the physiologic responses in both cell types. Neurons identified by synaptotagmin immunoreactivity were characterized functionally by the fast Ca2+ increase with K+ (50 mM) stimulation, and the astrocytes identified by glial fibrillary acidic protein (GFAP) staining had the functional characteristic of a transient Ca2+ peak in response to ATP (10 μM) stimulation. We found that the glutamate‐mediated Ca2+ response in neurons is due largely to influx of extracellular Ca2+. This is consistent with our finding that in cultured hippocampal neurons, stores depending on the activity of the sarcoendoplasmic reticulum Ca2+ ATPase (SERCA) pump had a low Ca2+ content, regardless of whether the neurons were challenged or not with K+ before applying the SERCA inhibitor cyclopiazonic acid (CPA). Astrocytes displayed a large CPA‐mediated Ca2+ response, indicating a high level of Ca2+ load in the stores in astrocytes. Importantly, the rise in ROS generation due to glutamate application was cell‐type specific. In neurons, glutamate induced a marked rise in generation of ROS, but not in astrocytes. In both astrocytes and neurons, the mitochondrial potential was increased in response to glutamate challenge. We conclude that in neurons, Ca2+ influx accounts for the increased ROS generation in response to glutamate. This might explain the high vulnerability of neurons to glutamate challenge compared to the vulnerability of astrocytes. The high resistance of astrocytes is accompanied by an efficient downregulation of cytosolic Ca2+, which is not found in neurons. © 2004 Wiley‐Liss, Inc.
Whither franchising? The case of Avis Europe PLC
Authors: Jacobsen Lowell R. 
Published: December 2004

AbstractThis case study of Avis Europe PLC examines the diminished role of franchising in the vehicle leasing firm's achievement of market dominance in Europe. Market maturity, industry consolidation, adoption of centralised, efficiency‐oriented technologies, and strategic alliances are the principal factors in accounting for the decline in the reliance on franchisees for local entrepreneurship and market expansion. Though many theories of franchising find at least some support in this study, the life cycle or ownership redirection explanation proves particularly compelling. Copyright © 2004 John Wiley & Sons, Ltd.
A conforming unified finite element formulation for the vibration of thick beams and frames
Authors: Hirdaris Spyridon E. , Lees Arthur W. 
Published: December 2004

AbstractBeams and frames are common features in many engineering structures and in this paper an approach is given to model their dynamic behaviour adequately. Whilst the eigen‐frequencies of continuous systems comprising of slender beams can be identified, in most cases of practical interest, by means of Euler or Timoshenko beam theory, for structures comprising of thick beam models this is not necessarily true since such idealizations constrain the cross‐sections to remain planar. This paper suggests an alternative approach by means of a unified fully conforming plane stress rectangular finite element which is believed to allow for more realistic representation of the shear effects and hence the strain field around the joints of such structures. The usefulness and functionality of this improved numerical approach is explored via comparison against a non‐conforming two‐dimensional plate as well as one‐dimensional Euler–Bernoulli and Timoshenko finite element formulations corresponding to a variety of beam aspect ratios representing the structures of a rotor and a portal frame. The idealization is shown to be particularly advantageous for simulating the effects of shear distortion where beams join at right angles and the transverse forces in one member interact with the extensional forces of the adjoining structure. Copyright © 2004 John Wiley & Sons, Ltd.
Poly(butylene terephthalate)–clay nanocomposites prepared by melt intercalation: morphology and thermomechanical properties
Authors: Chang Young‐Wook , Kim Suksoo , Kyung Youngbin 
Published: December 2004

AbstractNanocomposites based on poly(butylene terephthalate) (PBT) and an organoclay (Cloisite 30B) were prepared by melt blending using a twin‐screw extruder. Two kinds of PBTs, ie PBT‐A and PBT‐B, with different inherent viscosities (ηinh), were used for this study (ηinh of PBT‐A and PBT‐B were 0.74 and 1.48, respectively). Dispersion of the clay layers in the PBT nanocomposites was characterized by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile and dynamic mechanical properties and non‐isothermal crystallization temperatures of the nanocomposites were also examined. Nanocomposites based on the higher‐viscosity PBT (PBT‐B) showed a higher degree of exfoliation of the clay and a higher reinforcing effect when compared to the composites based on the lower‐viscosity PBT (PBT‐A). The clay nanolayers dispersed in PBT matrices lead to increases in the non‐isothermal crystallization temperatures of the PBTs, with such increases being more significant for the PBT‐B nanocomposites than for the PBT‐A nanoocomposites. Copyright © 2004 Society of Chemical Industry
Synthesis and properties of poly(isobutyl methacrylate‐co‐butanediol dimethacrylate‐co‐methacryl polyhedral oligomeric silsesquioxane) nanocomposites
Authors: Li Gui Zhi , Cho Hosouk , Wang Lichang , Toghiani Hossein , Pittman Charles U. 
Published: December 2004

AbstractPoly[isobutyl methacrylate‐co‐butanediol dimethacrylate‐co‐3‐methacrylylpropylheptaisobutyl‐T8‐polyhedral oligomeric silsesquioxane] [P(iBMA‐co‐BDMA‐co‐MA‐POSS)] nanocomposites with different crosslink densities and different polyhedral oligomeric silsesquioxane (MA‐POSS) percentages (5, 10, 15, 20, and 30 wt %) were synthesized by radical‐initiated terpolymerization. Linear [P(iBMA‐co‐MA‐POSS)] copolymers were also prepared. The viscoelastic properties and morphologies were studied by dynamic mechanical thermal analysis, confocal microscopy, and transmission electron microscopy (TEM). The viscoelastic properties depended on the crosslink density. The dependence of viscoelastic properties on MA‐POSS content at a low BDMA loading (1 wt %) was similar to that of linear P(iBMA‐co‐MA‐POSS) copolymers. P(iBMA‐co‐1 wt % BDMA‐co‐10 wt % MA‐POSS) exhibited the highest dynamic storage modulus (E′) values in the rubbery region of this series. The 30 wt % MA‐POSS nanocomposites with 1 wt % BDMA exhibited the lowest E′. However, the E′ values in the rubbery region for P(iBMA‐co‐3 wt % BDMA‐co‐MA‐POSS) nanocomposites with 15 and 30 wt % MA‐POSS were higher than those of the parent P(iBMA‐co‐3 wt % BDMA) resin. MA‐POSS raised the E′ values of all P(iBMA‐co‐ 5 wt % BDMA‐co‐MA‐POSS) nanocomposites in the rubbery region above those of P(iBMA‐co‐5 wt % BDMA), but MA‐POSS loadings < 15 wt % had little influence on glass‐transition temperatures (Tg's) and slightly reduced Tg values with 20 or 30 wt % POSS. Heating history had little influence on viscoelastic properties. No POSS aggregates were observed for the P(iBMA‐co‐1 wt % BDMA‐co‐MA‐POSS) nanocomposites by TEM. POSS‐rich particles with diameters of several micrometers were present in the nanocomposites with 3 or 5 wt % BDMA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 355–372, 2005
Mixture and mixture–process variable experiments for pharmaceutical applications
Authors: Anderson‐Cook Christine M. , Goldfarb Heidi B. , Borror Connie M. , Montgomery Douglas C. , Canter Kelly G. , Twist John N. 
Published: December 2004

AbstractMany experiments in research and development in the pharmaceutical industry involve mixture components. These are experiments in which the experimental factors are the ingredients of a mixture and the response variable is a function of the relative proportion of each ingredient, not its absolute amount. Thus the mixture ingredients cannot be varied independently. A common variation of the mixture experiment occurs when there are also one or more process factors that can be varied independently of each other and of the mixture components, leading to a mixture–process variable experiment. We discuss the design and analysis of these types of experiments, using tablet formulation as an example. Our objective is to encourage greater utilization of these techniques in pharmaceutical research and development. Copyright © 2004 John Wiley & Sons Ltd.
Calcium signaling via voltage‐dependent L‐type Ca2+ channels
Authors: Naguro Isao , Adachi‐Akahane Satomi , Ichijo Hidenori 
Published: December 2004

AbstractIn excitable cells such as muscles and neurons, the voltage‐dependent L‐type Ca2+ channel is one of the most important pathways for Ca2+ influx from extracellular space in response to the cell membrane depolarization. Ca2+ ion through this channel works as a Ca2+ signal that regulates fast (on time scale of milliseconds; e.g. muscle contraction) and long‐term (on a time scale of days or weeks; e.g. gene expression) cellular responses. Many important signal molecules are activated via Ca2+ signal, such as Ca2+‐dependent protease (calpain), calcium/calmodulin dependent kinases (CaMKs), phosphatase (calcineurin), and mitogen‐activated protein kinases (MAPKs). They are activated by temporally and spatially restricted Ca2+ signals, thus strictly regulated in native tissues. Many kinds of Ca2+ channels are involved in the rise of the intracellular Ca2+ concentration. They are not mere routes of Ca2+ influx but also machineries that decide which specific signal cascade should be activated. Recently, the molecular mechanisms by which Ca2+ influx through L‐type Ca2+ channels can activate specific signal cascades have been clarified. In this review, we describe the role of Ca2+ signaling via L‐type Ca2+ channels particularly in cardiac myocytes and neurons with emphasis on the mechanisms underlying the activation of the specific Ca2+ signals by the L‐type Ca2+ channel machinery.
Ionengestützte Beschichtungsprozesse in situ kontrollieren. Ion assisted deposition processes: in situ control
Authors: Ehlers Henrik , Groß Tobias , Lappschies Marc , Ristau Detlev 
Published: December 2004

AbstractIonengestützte Beschichtungsprozesse für optische Präzisionskomponenten weisen insbesondere im nahen und mittleren infraroten Spektralbereich ein hohes Potenzial auf. Die vorgestellten Ergebnisse belegen das wichtige Kriterium eines minimierten Wassereinbaus in den Schichtstrukturen sowohl durch Messungen der optischen Verluste im Wellenlängenbereich um 3 μm als auch durch die Bestimmung der spektralen Stabilität der Optiken. Der Einsatz eines in situ Monitors, der breitbandige Transmissionsmessungen direkt am Produkt ermöglicht, liefert zudem eine umfangreiche Datenbasis für die Prozessanalyse und –entwicklung. So stehen zusätzliche Informationen über das Aufwachsverhalten, die Vakuum‐Luft‐Shift sowie über Schichtinhomogenitäten zur Verfügung. Die Verknüpfung des in situ Monitors mit der Anlagensteuerung ergibt ein automatisiertes System für die Prozesskontrolle, das auf einer präzisen Bestimmung der Schichtdicke aufsetzt und eine Ausgangsbasis für das Rapid Prototyping komplexer Schichtsysteme darstellt. Hierbei kann, im Gegensatz zu Standardmonitorstrategien, auf Testbeschichtungen und Kalibrationsfaktoren verzichtet werden. Mit der vorgestellten Kombination des stabilen ionengestützten Beschichtungsprozesses und des in situ Monitors konnte die Herstellung anspruchsvoller NIR‐/ MIR‐Schichtsysteme bei einer hohen Reproduzierbarkeit automatisiert werden.
Das 6. Rahmenprogramm der EU – Chance und Herausforderung für die Industrie. The 6th Framework programme of the EC – chance and challenge for industry
Authors: Wey Karin 
Published: December 2004

AbstractIm November 2002 wurde das 6. Forschungsrahmenprogramm 2002 bis 2006 offiziell eröffnet. Es ist mit insgesamt 17,5 Milliarden Euro ausgestattet, was eine Steigerung von 17 % gegenüber seinem Vorgängerprogramm bedeutet. Wie auch seine Vorgängerprogramme, hat das 6. Forschungsrahmenprogramm (FRP) das Ziel, die wissenschaftlichen und technologischen Grundlagen der Industrie der Gemeinschaft zu stärken und die Entwicklung ihrer internationalen Wettbewerbsfähigkeit zu fördern. Darüber hinaus soll das 6. FRP einen Beitrag zur Schaffung des Europäischen Forschungsraums und zur Innovation leisten. Durch veränderte Randbedingungen und neue Möglichkeiten, Projektanträge einzureichen, ist es jedoch schwieriger geworden, von den prall gefüllten Fördertöpfen der EU zu partizipieren.Der Artikel gibt eine Übersicht über die Struktur und die administrativen Randbedingungen der Förderungen und zeigt Fördermöglichkeiten für den Bereich „Nanotechnologie, Werkstoffe und Produktion”︁ auf.