bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cholestane‐3β,5α,6β‐triol inhibits osteoblastic differentiation and promotes apoptosis of rat bone marrow stromal cells
Authors: Liu Hongmei , Yuan Lan , Xu Shanjin , Wang Kui , Zhang Tianlan 
Published: July 2005

AbstractConverging lines of evidence suggest that oxidized lipids, long recognized as a risk factor in atherogenesis, also contribute to osteoporosis, but the underlying mechanism is not understood in detail. The effect of atherogenesis related factors including oxysterols on the differentiation and survival of marrow stromal cells (MSCs) would be very important in understanding the link between atherosclerosis and osteoporosis. In the present study, the effect of oxysterol cholestane‐3β,5α,6β‐triol (Triol) on osteoblastic differentiation and apoptosis of primary rat bone MSCs as well as the related mechanisms were studied. Triol inhibited MSCs osteoblastic differentiation as demonstrated by inhibition of alkaline phosphatase activity, osteocalcin secretion, and matrix mineralization. In the other aspect, Triol promoted MSCs apoptosis, as characterized by condensed or fragmented nuclei as well as active externalization of phosphatidyl serine to the cell surface. In addition, Triol was found to induce increases of intracellular Ca2+ and Ca2+‐dependent reactive oxygen species generation in MSCs. These effects were involved in the action of Triol on apoptosis, but not on osteoblastic differentiation of MSCs. These results suggested that Triol might contribute to the decreased bone formation by inhibition of osteoblastic differentiation and promotion of apoptosis of MSCs, providing insights about common factors underlying the pathogenesis of atherosclerosis and osteoporosis. © 2005 Wiley‐Liss, Inc.
Tyrosine phosphatases as regulators of skeletal development and metabolism
Authors: Schiller Katherine R. , Mauro Laura J. 
Published: July 2005

AbstractThe protein tyrosine kinases (PTK) and the protein tyrosine phosphatases (PTPs) are enzymes which play an integral role in tyrosine phosphorylation‐dependent signaling cascades. By catalyzing the phosphorylation and dephosphorylation of cellular proteins, these enzymes direct the steady‐state levels of specific phosphoproteins and ultimately dictate the functional state of all cells. The importance of this type of signaling in the skeleton is accepted but poorly understood. The contribution of the PTKs to signaling events in bone has been well studied but, in contrast, the regulation by PTPs is poorly defined. The recent identification of 107 genes within the human genome which encode members of the PTP superfamily emphasizes the need to consider the importance of these proteins in skeletal tissue. In this prospective, we will summarize the present state of our knowledge regarding the function of this enzyme superfamily, illustrating its relevance to the development and maintenance of the skeleton and highlighting future directions that should improve our understanding of these critical signaling molecules. © 2005 Wiley‐Liss, Inc.
Repair of DNA interstrand crosslinks may take place at the nuclear matrix
Authors: Atanassov Boyko , Gospodinov Anastas , Stoimenov Ivaylo , Mladenov Emil , Russev George , Tsaneva Irina , Anachkova Boyka 
Published: July 2005

AbstractHost cell reactivation assay using Trioxsalen‐crosslinked plasmid pEGFP‐N1 showed that human cells were able to repair Trioxsalen interstrand crosslinks (ICL). To study the mechanism of this repair pathway, cells were transfected with the plasmids pEGFP‐1, which did not contain the promoter of the egfp gene, and with pEGFP‐G−, which did not contain the egfp gene. Neither of these plasmids alone was able to express the green fluorescent protein. After cotransfection with the two plasmids, 1%–2% of the cells developed fluorescent signal, which showed that recombination events had taken place in these cells to create DNA constructs containing the promoter and the gene properly aligned. When one or both of the plasmids were crosslinked with Trioxsalen, the recombination rate increased several fold. To identify the nuclear compartment where recombination takes place, cells were transfected with crosslinked pEGFP‐N1 and the amount of plasmid DNA in the different nuclear fractions was determined. The results showed that Trioxsalen crosslinking increased the percentage of matrix attached plasmid DNA in a dose‐dependant way. Immunoblotting experiments showed that after transfection with Trioxsalen crosslinked plasmids the homologous recombination protein Rad51 also associated with the nuclear matrix fraction. These studies provide a model system for investigating the precise molecular mechanisms that appear to couple repair of DNA ICL with nuclear matrix attachment. © 2005 Wiley‐Liss, Inc.
Leptin expression in human primary skeletal muscle cells is reduced during differentiation
Authors: Solberg Rigmor , Aas Vigdis , Thoresen G. Hege , Kase Eili Tranheim , Drevon Christian A. , Rustan Arild C. , Reseland Janne E. 
Published: July 2005

AbstractWe found leptin to be strongly expressed in undifferentiated human myoblasts derived from biopsies of the thigh (Musculus vastus lateralis). Both mRNA expression and secretion of leptin were reduced during in vitro differentiation into primary myotubes. However, the expression of the leptin receptor (OB‐Rb) mRNA, was unchanged during differentiation of the muscle cells. Administration of recombinant leptin had no effect on leptin, myogenin, myoD, or GLUT4 mRNA expressions during the period of cellular differentiation. A functional leptin receptor was demonstrated by an acute leptin‐induced 1.5‐fold increase in ERK activity (P = 0.029). Although mRNA expression of regulation of suppressor of cytokine signaling‐3 (SOCS‐3) mRNA expression was unaltered, leptin significantly stimulated fatty acid oxidation after 6 h measured as acid soluble metabolites (ASM). Palmitic acid (PA), oleic acid (OA), and eicosapentaenoic acid (EPA), known to modulate leptin expression in other tissues, had no effect on mRNA expression or secretion of leptin from human myotubes. In conclusion, we demonstrate that leptin is highly expressed in undifferentiated human myoblasts and the expression is reduced during differentiation to mature myotubes. The role of leptin in these cells needs to be further characterized. © 2005 Wiley‐Liss, Inc.
Suppressive effect of regucalcin on cell differentiation and mineralization in osteoblastic MC3T3‐E1 cells
Authors: Yamaguchi Masayoshi , Kobayashi Mayumi , Uchiyama Satoshi 
Published: July 2005

AbstractThe role of regucalcin in the regulation of osteoblastic cell function was investigated. Osteoblastic MC3T3‐E1 cells with subconfluent monolayers were cultured in a medium containing regucalcin (10−10–10−8 M) without fetal bovine serum (FBS). The proliferation of osteoblastic cells was not significantly altered in the presence of regucalcin. The results of reverse transcription‐polymerase chain reaction (RT‐PCR) analysis with specific primers showed that the expression of Runx2 (Cbfa1) and insulin‐like growth factor‐I (IGF‐I) mRNAs in osteoblastic cells was significantly suppressed in the presence of regucalcin (10−10 or 10−9 M). Transforming growth factor‐β1 mRNA levels were significantly enhanced in the 24 h‐culture with regucalcin (10−10 or 10−9 M). α1(I) collagen and glyceroaldehyde‐3‐phosphate dehydrogenase (G3PDH) mRNA levels were not significantly changed by culture with regucalcin (10−10 or 10−9 M). Alkaline phosphatase activity was significantly decreased in the lysate of cells cultured for 24 or 48 h with regucalcin (10−10–10−8 M). Moreover, the expression of regucalcin in osteoblastic cells was demonstrated by RT‐PCR and Western blot analysis. When regucalcin (10−7 M) was added into the enzyme reaction mixture containing the lysate of osteoblastic cells cultured in the absence of regucalcin, alkaline phosphatase activity was significantly decreased. Also, Ca2+/calmodulin‐dependent nitric oxide (NO) synthase activity in the cell lysate was significantly decreased by addition of regucalcin (10−10–10−8 M) into the reaction mixture. The presence of anti‐regucalcin monoclonal antibody (5 or 10 ng/ml) in the enzyme reaction mixture caused a significant increase in NO synthase activity in the cell lysate in the presence or absence of Ca2+/calmodulin, suggesting a role of endogenous regucalcin. When osteoblastic cells with subconfluency were cultured in the presence of regucalcin (10−10 or 10−9 M) for 3, 9, or 18 days, the results with Alizarin red staining showed that the mineralization was markedly suppressed by culture with regucalcin for 3, 9, or 18 days. This study demonstrates that regucalcin regulates the function of osteoblastic cells, and that the protein suppresses cell differentiation and mineralization. © 2005 Wiley‐Liss, Inc.
Differential localization of acetylcholinesterase in neuronal and non‐neuronal cells
Authors: Thullbery Matthew D. , Cox Holly D. , Schule Travis , Thompson Charles M. , George Kathleen M. 
Published: July 2005

AbstractAcetylcholinesterase (AChE) expression is regulated in cell types at the transcriptional and translational levels. In this study, we characterized and compared AChE catalytic activity, mRNA, protein expression, and protein localization in a variety of neuronal (SH‐SY5Y neuroblastoma and primary cerebellar granule neurons (CGN)) and non‐neuronal (LLC‐MK2, HeLa, THP‐1, and primary astrocytes) cell types. All cell lines expressed AChE catalytic activity; however the levels of AChE‐specific activity were higher in neuronal cells than in the non‐neuronal cell types. CGN expressed significantly more AChE activity than SH‐SY5Y cells. All cell lines analyzed expressed AChE protein at equivalent levels, as well as mRNA splice variants. Localization of AChE was characterized by immunofluorescence and confocal microscopy. SH‐SY5Y, CGN, and nerve‐growth factor‐differentiated PC‐12 cells exhibited a pattern of AChE localization characterized as diffuse in the cytoplasm and punctate staining along neurites and on the plasma membrane. The localization in HeLa, LLC‐MK2, fibroblasts, and undifferentiated PC‐12 cells was significantly different than in neuronal cells—AChE was intensely localized in the perinuclear region, without staining near or on the plasma membrane. Based on the evidence presented here, we hypothesize that the presence of AChE protein doesn't correlate with catalytic activity, and the diffuse cytoplasmic and plasma membrane localization of AChE is a property of neuronal cell types. © 2005 Wiley‐Liss, Inc.
A new multiplex assay allowing simultaneous detection of the inhibition of cell proliferation and induction of cell death
Authors: Węsierska‐Gądek Józefa , Gueorguieva Marieta , Ranftler Carmen , Zerza‐Schnitzhofer Gerlinde 
Published: July 2005

AbstractThe efficacy of distinct anti‐cancer drugs used in the chemotherapy of human malignancies varies between tumor tissues and depends largely on the ability of the therapeutic agents to simultaneously inhibit cell proliferation and to eliminate malignant cells by apoptosis. Especially, detection of early apoptotic changes seems to be important because early stages of apoptosis differ from those of necrosis. Therefore, the development of a novel test allowing fast and concomitant screening of the anti‐proliferative and pro‐apoptotic action of a number of anti‐cancer drugs is of great interest. For this purpose, we choose as an experimental model a well characterized anti‐proliferative and pro‐apoptotic effect of cisplatin (CP) on human cervical carcinoma HeLaS3 cells. As previously reported, exposure of HeLaS3 to CP resulted in a concomitant inhibition of cell proliferation and induction of apoptosis in a dose‐ and time‐dependent manner. In the present study we performed two independent approaches. In the first approach, we examined the cell proliferation and activity of caspases‐3/7 in two separate microtiter plates using the CellTiter‐Glo™ Luminescent Cell Viability Assay and the Caspase‐Glo™ 3/7 Assay, respectively. In the second approach, we determined the same parameters sequentially in one microtiter plate by a mutiplexing assay using CellTiter‐Blue™ Cell Viability Assay and Caspase‐Glo™ 3/7 Assay. The both approaches gave very similar results indicating that this new multiplexing assay offers an important advantage for simultaneous detection of cell number and activation of caspases‐3/7. The new multiplexing assay offers a range of benefits over standard assays. © 2005 Wiley‐Liss, Inc.
Functional role of PKC in contraction of cultured human prostatic stromal cells
Authors: Takahashi Ryosuke , Nishimura Junji , Hirano Katsuya , Naito Seiji , Kanaide Hideo 
Published: July 2005

AbstractThe contractile activity of prostatic stromal cells contributes to symptoms of benign prostatic hyperplasia (BPH). However, the mechanisms for this contraction have not yet been fully elucidated. In this study, we investigated the role of protein kinase C (PKC) in prostatic contraction by measuring the isometric tension development of cultured human prostatic stromal cells (CHPSCs) derived from BPH patients. Fresh human BPH tissue was used only in a Western blot analysis. A ring preparation made of CHPSCs and collagen gel could develop an isometric tension during activation with various agonists. Phorbol 12,13 dibutyrate (PDBu), a PKC activator, induced a relaxation. A Western blot analysis revealed the expression of PKC‐potentiated protein phosphatase‐1 inhibitory protein (CPI‐17) in both CHPSCs and fresh human BPH tissue to be much lower than that in the rabbit aorta. When CPI‐17 was over‐expressed, PDBu induced a large contraction, but the agonist‐induced contraction did not become larger than expected. In α‐toxin permeabilized preparations, PDBu induced a relaxation in control CHPSCs, while it induced a contraction at a constant [Ca2+]i in CPI‐17 over‐expressing CHPSCs. These results indicated that the activation of PKC in CHPSCs induces a relaxation probably due to low expression level of CPI‐17 and also that the PKC‐CPI‐17 pathway does not appear to play a major role in the agonist‐induced contraction even when CPI‐17 was over‐expressed. © 2005 Wiley‐Liss, Inc.
Differential expression of antioxidant enzymes in various hepatocellular carcinoma cell lines
Authors: Yang Liang‐Yo , Chen Wei‐Li , Lin Jia‐Wei , Lee Shu‐Fen , Lee Chin‐Cheng , Hung Tsung I , Wei Yau‐Huei , Shih Chwen‐Ming 
Published: July 2005

AbstractRecent evidence suggests that reactive oxygen species (ROS) play an important role in the pathogenesis of various illnesses, and the ROS and antioxidant enzymes are highly associated with cell differentiation and diseases. In this study, we tested the hypothesis that specific antioxidant enzymes are differentially expressed in hepatocellular carcinoma (HCC) cell lines with various degrees of differentiation. We compared the expression of several antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GRx), and glutathione peroxidase (GPx) in five HCC cell lines with well (Hep G2 and Hep 3B) or poor (HA22T/VGH, HA55T/VGH, and SK‐Hep‐1) differentiation. Our results showed that both well‐differentiated HCC cell lines expressed extremely higher CAT and GRx enzyme activities than all three poorly differentiated ones. Moreover, the protein and mRNA levels of CAT were much higher in two well‐differentiated HCC cell lines than in all three poorly differentiated ones. Both well‐differentiated HCC cell lines also showed a higher protein or mRNA expression of Cu/ZnSOD and MnSOD than three poorly differentiated ones. Our results demonstrate that specific antioxidant enzymes (especially, CAT and GRx) are differentially expressed in HCC cell lines with well or poor differentiation. These findings suggest that CAT and GRx are two potential differentiation markers for HCC. © 2005 Wiley‐Liss, Inc.
Cross‐talk among epidermal growth factor, Ap5A, and nucleotide receptors causing enhanced ATP Ca2+ signaling involves extracellular kinase activation in cerebellar astrocytes
Authors: Delicado Esmerilda G. , Jiménez Ana I. , Carrasquero Luz María G. , Castro Enrique , Miras‐Portugal Mª Teresa 
Published: July 2005

AbstractIn previous papers, we reported that ATP calcium responses in cerebellar astrocytes were strongly potentiated by preincubation with nanomolar concentrations of the diadenosine pentaphosphate Ap5A. However, the intracellular signaling pathway mediating this effect was not defined. We also showed that stimulation of astrocytes with the dinucleotide led to the activation of extracellular regulated kinases (ERKs). Here, we examined whether ERKs are involved in the potentiating mechanism and intracellular mechanism leading to their activation. Epidermal growth factor (EGF) exactly reproduced the potentiation displayed by the dinucleotide. Moreover, the potentiation of ATP responses by Ap5A and EGF was completely abolished by the MAP kinase (MEK) inhibitor U‐0126, indicating that ERK activation is a required step for the potentiation event. Our data also indicated that ERK activation and the potentiation of ATP calcium responses were sensitive to the src‐like kinase inhibitor herbimycin A, p21ras farnesyltransferase inhibitor peptide, and some PKC inhibitors. Taken together, our findings reveal that Ap5A triggers the potentiation of ATP calcium responses through an intracellular mechanism that is insensitive to pertussis toxin and that this potentiation requires src protein‐mediated ERK activation and the participation of an atypical protein kinase C isoform activated downstream from ERK. © 2005 Wiley‐Liss, Inc.
Nanocomposites of NLO chromophore‐modified layered silicates and polypropylene
Authors: Dudkina Marina M. , Tenkovtsev Andrey V. , Pospiech Doris , Jehnichen Dieter , Häußler Liane , Leuteritz Andreas 
Published: July 2005

AbstractIntercalation of guest species into layered inorganic solids is a method of producing ordered inorganic–organic assemblies with unique microstructures controlled by host–guest and guest–guest interactions. Smectite clay minerals, such as montmorillonite, having appropriate functional molecules in between the silicate layers are supposed to exhibit a wide range of novel characteristics. Nanocomposite material based on maleic anhydride‐grafted polypropylene and dye‐modified layered silicate was developed. Characteristics of organo‐modified montmorillonite particles and polymer/clay hybrids have been investigated through FTIR, SAXS, DSC, UV measurements, and transmission electron microscopy. The results of the intercalation process, structural characterization, and thermal properties will be discussed in comparison with the intercalation and nanocomposite preparation results. The intercalation was successfully conducted by the ion‐exchange method. It was shown that intercalated dibenzilidene acetone type chromophores exist in the clay galleries in an aggregated form, probably as J‐aggregates. This feature strongly effects on optical and nonlinear optical properties of nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2493–2502, 2005
Surface film formation on a graphite electrode in Li‐ion batteries: AFM and XPS study
Authors: Leroy S. , Blanchard F. , Dedryvère R. , Martinez H. , Carré B. , Lemordant D. , Gonbeau D. 
Published: July 2005

AbstractThe formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO2/graphite lithium‐ion cells using LiPF6 (1M) in carbonate solvents as electrolyte was investigated by means of x‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The analyses were carried out at different potentials of the first and the fifth cycles, showing the potential‐dependent character of the surface‐film species formation. These species were mainly identified as Li2CO3 up to 3.8 V and LiF up to 4.2 V. This study shows the formation of the SEI during charging and its partial dissolution during discharge. Copyright © 2005 John Wiley & Sons, Ltd.
Grid interaction of offshore wind farms. Part 2. Case study simulations
Authors: Morren Johan , Pierik Jan T. G. , Haan Sjoerd W. H. de , Bozelie Jan 
Published: July 2005

AbstractOwing to an increasing penetration of wind turbines and large wind farms in electrical power systems, the wind turbines start influencing the overall power system behaviour. Dynamic wind farm models for power system studies have been presented in Part 1 of the article. In this contribution, these models are applied in a number of case studies to determine the impact of wind farms on the power grid. Four turbine concepts are evaluated with respect to their grid interaction. Case studies involving normal behaviour, voltage dip behaviour, voltage control capability and behaviour during frequency deviations will be presented. Copyright © 2005 John Wiley & Sons, Ltd.
Large‐scale wind power integration in Norway and impact on damping in the Nordic grid
Authors: Hagstrøm Espen , Norheim Ian , Uhlen Kjetil 
Published: July 2005

AbstractThe Nordic energy market is in need of new power generation capacity. Norway is today in shortage of electrical energy, and the hydropower‐based system must rely on importing electrical power from its neighbours in a normal year of hydro inflow. One solution to this problem is to invest in new generation capacity, e.g. by integrating more wind power into the Norwegian grid. The Norwegian government has announced that 1000 MW of wind power will be installed in Norway by 2010, corresponding to an eventual energy production of approximately 3 TWh year−1. This article investigates the impact of wind power integration in Norway on the damping of interarea mode oscillations in the Nordic grid. The impact on the interarea mode oscillations is tested for various types of generators. Results from computer analyses of a simplified yet realistic equivalent of the Nordic power system are used to compute the interarea mode oscillations. Copyright © 2005 John Wiley & Sons, Ltd.
Ecosystem structure and soil‐surface conditions drive the variability in the foliar δ13C and δ15N ofStipa tenacissimain semiarid Mediterranean steppes
Authors: Maestre Fernando T. , Cortina Jordi 
Published: July 2005

AbstractWe evaluated the effects of ecosystem composition and structure (species richness and diversity, cover and spatial attributes of vegetation), abiotic factors (climate and topographical features) and the condition of the bare‐ground areas (evaluated using soil‐surface indicators) on the performance ofStipa tenacissima[evaluated using foliar δ13C, δ15N, nitrogen concentration and the carbon‐to‐nitrogen (C:N) ratio] in 15 steppes of SE Spain. Foliar δ13C values ofS. tenacissimashowed a low degree of variation in the studied steppes, with average values ranging from −24.1 to −22.9‰. Higher variation was found in the δ15N values, which ranged from −5.5 to −2.4‰. The nitrogen concentration and the C:N ratio varied between 5.0 and 8.0 mg g−1, and between 55.4 and 85.3, respectively. The δ13C values became less negative with increasing spatial aggregation of perennial vegetation, while the C:N values increased with increasing perennial vegetation cover. The δ15N values became more negative with increasing infiltration in the bare‐ground areas, but the nitrogen concentration was not related to any of the environmental variables measured. Our results suggest that the relative importance of ecosystem structure and soil‐surface conditions in the bare ground areas was higher than that of abiotic factors as determinants of the performance ofS. tenacissima. The results also show that even subtle changes in these ecosystem features may lead to modifications in plant performance in semiaridS. tenacissimasteppes, and thus to modifications in the associated ecosystem functions in the mid‐ to long‐term.