bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of physicochemical reactions of bioactive glass on the behavior and activity of human osteoblasts in vitro
Authors: Josset Y. , Nasrallah F. , Jallot E. , Lorenzato M. , Dufour‐Mallet O. , Balossier G. , Laurent‐Maquin D. 
Published: November 2003

AbstractBioactive glasses are characterized by a bond to bone with a hydroxyl carbonate apatite layer. They enhance bone tissue formation and for this purpose are used in orthopedic surgery and in dental implantology. In the current work, we studied the biological response of human osteoblasts with a bioactive glass. This bioactive glass is based on 50% Si02, 20% Na2O, 16% CaO, 6% P2O5, 5% K20, 2% Al2O3 and 1% MgO and designated A9. Cracks and irregularities were observed on the material surface when it was immersed in the culture medium. In addition, energy dispersive X‐ray analyses highlighted a selective release of the elements at the surface of the bioactive glass, such as Na+ and K+ ions, released from the first day, contrary to the Si, Al, Ca, P, and Mg elements, which were released more slowly. Cell proliferation kinetics, total protein synthesis, and DNA content of the osteoblasts in contact with bioactive glass were similar to control cells. The morphological studies by light and scanning electron microscopy revealed an increasing cellular density in culture with bioactive glass without contact inhibition. The immunohistochemical studies highlighted the expression of types I, III, and V collagens by osteoblasts cultured in the presence of bioactive glass. The pH measurement of the culture medium in the presence of bioactive glass demonstrated a slight alkalinization. We thus conclude that human osteoblasts preserve their properties in the presence of bioactive glass (A9). © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1205–1218, 2003
Surface potential change in bioactive titanium metal during the process of apatite formation in simulated body fluid
Authors: Kim Hyun‐Min , Himeno Teruyuki , Kawashita Masakazu , Lee Ju‐Hyung , Kokubo Tadashi , Nakamura Takashi 
Published: November 2003

AbstractBioactive titanium metal can be prepared by NaOH and heat treatments that present the metal with a graded bioactive surface layer of amorphous sodium titanate. This study used laser electrophoresis together with transmission electron microscopy (TEM) and energy‐dispersive X‐ray microanalysis (EDX) to relate the surface potential change of the bioactive titanium metal with its surface structural change in simulated body fluid (SBF). The surface potential of the metal was highly negative immediately after immersion in SBF. With increasing soaking time, the surface potential increased, revealing a maximum positive value, and then decreased to a constant negative value. TEM‐EDX showed that immediately after immersion in SBF, the metal surface formed Ti‐OH groups by exchanging Na+ ions in the surface sodium titanate with H3O+ ions in the fluid. Thereafter, with increasing soaking time the metal surface formed an amorphous calcium titanate, then an amorphous calcium phosphate, and, finally, apatite with bone‐like composition and structure. These results indicate that the process of apatite formation on bioactive titanium metal is initiated by the formation of Ti‐OH groups with negative charges that interact with calcium ions with positive charges to form calcium titanate. The calcium titanate gains a positive charge and later interacts with phosphate ions with negative charges, forming amorphous calcium phosphate. The amorphous calcium phosphate eventually transforms and stabilizes into bone‐like crystalline apatite with a negative charge. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1305–1309, 2003
Biodegradable poly(ether‐ester) multiblock copolymers for controlled release applications
Authors: van Dijkhuizen‐Radersma R. , Roosma J.R. , Kaim P. , Métairie S. , Péters F.L.A.M.A. , de Wijn J. , Zijlstra P.G. , de Groot K. , Bezemer J.M. 
Published: November 2003

AbstractMultiblock poly(ether‐ester)s based on poly(ethylene glycol), butylene terephthalate, and butylene succinate units were synthesized by a two‐step melt polycondensation reaction, with the aim of developing a new series of degradable polymers for controlled release applications. The copolymers were characterized with respect to their composition (NMR), thermal properties (DSC), and swelling. The main focus was on the degradation kinetics and release properties of the copolymers. The crystallinity and swelling could be tailored by the PEG segment length and the ratio of the building units. With increasing mol fraction succinate in the hard segment, the swelling increased. The in vitro degradation was found to occur by molecular weight decrease and mass loss. Substitution of the aromatic terephthalate units by aliphatic succinate units increased the degradation rate of the copolymers. Polymers with PEG segments of 1000 kg/mol showed a more pronounced degradation than copolymers containing shorter and longer PEG segments. Model proteins were successfully incorporated and released from the poly(ether‐ester) films. Depending on the size of the protein, the release mechanism was based on diffusion of the protein and degradation of the matrix. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1294–1304, 2003
Differential gene expression analysis using paraffin‐embedded tissues after laser microdissection
Authors: Kim Joung‐Ok , Kim Hyun‐Nam , Hwang Mi‐Hye , Shin Hong‐In , Kim Shin‐Yoon , Park Rang‐Woon , Park Eui‐Yun , Kim In‐San , van Wijnen Andre J. , Stein Janet L. , Lian Jane B. , Stein Gary S. , Choi Je‐Yong 
Published: November 2003

AbstractRecent advances in laser microdissection allow for precise removal of pure cell populations from morphologically preserved tissue sections. However, RNA from paraffin‐embedded samples is usually degraded during microdissection. The purpose of this study is to determine the optimal fixative for RNA extractions from laser microdissected paraffin‐embedded samples. The integrity of RNA was evaluated with the intactness of 18S and 28S ribosomal RNA by electrophoresis and by the length of individual gene transcripts using RT‐PCR. The various fixatives were methacarn (a combination of methanol, chloroform, and acetic acid) and several concentrations of ethanol and isopropanol. Methacarn was the optimal fixative for RNA preservation in paraffin‐embedded tissues, which included liver, lung, kidney, muscle, and limb. Based on RT‐PCR analysis, methacarn fixed samples exhibited the expected RNA sizes for individual genes such as glyceraldehyde‐3‐phosphate‐dehydrogenase (GAPDH) and bone‐related genes (e.g., alkaline phosphatase and osteonectin). The laser microdissection technique with methacarn fixation was then applied to analyze the differential gene expression between hypertrophic and proliferative chondrocytes in the growth plate of long bone. The expression of type X collagen (ColXα1), a specific gene for hypertrophic chondrocytes, was only observed in hypertrophic chondrocytes, while type II collagen (Col2α1) was observed more broadly in the growth plate as anticipated. Thus, combining laser microdissection with methacarn fixation facilitates the examination of differentially expressed genes from various tissues. © 2003 Wiley‐Liss, Inc.
β‐phenylpyruvate and glucose uptake in isolated mouse soleus muscle and cultured C2C12 muscle cells
Authors: Ben‐Abraham Ron , Gazit Vered , Vofsi Oded , Ben‐Shlomo Izahar , Reznick Abraham Z. , Katz Yeshayahu 
Published: November 2003

AbstractPrevious investigation demonstrated the potential of β‐phenylpyruvate at high concentration to cause hypoglycemia in mice totally deprived of insulin. For further elucidation of the glucose‐lowering mechanism, glucose uptake, and quantity of glucose transporters (GLUT1 and GLUT4) in mouse soleus muscle and C2C12 muscle cell lines were investigated following incubation with β‐phenylpyruvate in various concentrations. A marked enhancement of glucose uptake was demonstrated that peaked at 0.5 and 1.0 mM β‐phenylpyruvate in soleus muscle (P < 0.01) and C2C12 cells (P < 0.001), respectively. Kinetic analysis in C2C12 cells showed a twofold increase in Vmax compared with controls (P < 0.001). In addition, both GLUT1 and GLUT4 levels were increased following exposure to β‐phenylpyruvate. Our findings point to a peripheral hypoglycemic effect of β‐phenylpyruvate. © 2003 Wiley‐Liss, Inc.
Identification of a novel protein from glial cells based on its ability to interact with NF‐κB subunitsr
Authors: Sweet Thersa , Khalili Kamel , Sawaya Bassel E. , Amini Shohreh 
Published: November 2003

AbstractNuclear factor κB (NF‐κB) represents a family of inducible DNA‐binding transcription factors whose activity is critical for expression of the HIV‐1 genome in a broad range of cells. In addition to its interaction with the κB DNA sequence, the association of NF‐κB subunits with other cellular proteins plays an important role in stimulation of HIV‐1 gene transcription in astrocytic cells. Here, we utilized a yeast two‐hybrid system to screen a cDNA library from a human astrocytic cell line and were able to isolate a partial cDNA belonging to a gene with an open reading frame of 1,871 amino acid residues which binds to both the p50 and p65 subunits of NF‐κB. This gene, named NF‐κB‐binding protein (NFBP) is located on chromosome 10q24.2‐25.1 and hybridized to a single transcript of nearly 6 kb in size. It is localized to the nucleus, specifically the nucleolus of cells. Extensive computer analysis was performed with the sequence of the full length NFBP and significant homology was found between NFBP, and yeast and mouse proteins. A discussion of the potential roles of NFBP in normal and viral infected cells is included. © 2003 Wiley‐Liss, Inc.
SHP‐1 suppresses cancer cell growth by promoting degradation of JAK kinases
Authors: Wu Chengyu , Guan Qin , Wang Yingjian , Zhao Z. Joe , Zhou G. Wayne 
Published: November 2003

AbstractSHP‐1 has been proposed to be a tumor suppressor gene for several cancers. The expression of SHP‐1 protein is diminished or abolished in most leukemia and lymphoma cell lines and tissues, and in some non‐hematopoietic cancer cell lines, such as estrogen receptor (ER) negative breast cancer cell lines and some colorectal cancer cell lines. However, we do not know whether the reduced SHP‐1 expression is the cause of cancer diseases or the secondary effect of cancer developments. Here, we first demonstrate that SHP‐1 has general tumor suppressing function in SHP‐1 transfected cell lines. Transfected SHP‐1 inhibits the growth of three lymphoma/leukemia cell lines (Ramos, H9, Jurkat) and one breast cancer cell line (HTB26). We also demonstrate a possible molecular mechanism for the tumor suppressing function of SHP‐1: SHP‐1 inhibits cell growth partly by negative regulation of activated JAK kinase. In addition, we find, for the first time, that SHP‐1 down‐regulates the level of TYK2 kinase in H9 cells and of JAK1 kinase in HTB26 cells, by accelerating their degradation. The SHP‐1 accelerated degradation of JAK1 kinase in HTB26 cells was blocked with the treatment of MG132, a specific inhibitor for proteasome‐mediated proteolysis. Our data suggest a new function of SHP‐1 in the regulation of proteasome‐mediated degradation pathway. © 2003 Wiley‐Liss, Inc.
Transcriptional regulation of collagenase‐3 by interleukin‐1 alpha in osteoblasts
Authors: Varghese Samuel , Canalis Ernesto 
Published: November 2003

AbstractInterleukin‐1 (IL‐1)α is an autocrine/paracrine agent of the skeletal tissue and it regulates bone remodeling. Collagenase‐3 or matrix metalloproteinase (MMP)‐13 is expressed in osteoblasts and its expression is modulated by several cytokines including IL‐1α. Because the molecular mechanism of increased synthesis of collagenase‐3 in bone cells by IL‐1α is not known, we investigated if collagenase‐3 expression by IL‐1α in osteoblasts is mediated by transcriptional or post‐transcriptional mechanisms. Exposure of rat osteoblastic cultures (Ob cells) to IL‐1α at concentrations higher than 0.5 nM increased the synthesis of collagenase‐3 mRNA up to eightfold and the secretion of immunoreactive protein up to 21‐fold. The effects of IL‐1α on collagenase‐3 were time‐ and dose‐dependent. Although prostaglandins stimulate collagenase‐3 expression, stimulation of collagenase‐3 in Ob cells by IL‐1α was not mediated through increased biosynthesis of prostaglandins. The half‐life of collagenase‐3 mRNA from control and IL‐1α‐treated Ob cells was similar suggesting that the stabilization of collagenase‐3 mRNA did not contribute to the increase in collagenase‐3. However, IL‐1α stimulated the rate of transcription of the collagenase‐3 gene by twofold to fourfold indicating regulation of collagenase‐3 expression in Ob cells at the transcriptional level. Stimulation of collagenase‐3 by IL‐1α in osteoblasts may in part mediate the effects of IL‐1α in bone metabolism. © 2003 Wiley‐Liss, Inc.
Performance of PML absorbing boundary conditions in 3D photonic crystal waveguides
Authors: Weily Andrew R. , Horvath Levente , Esselle Karu P. , Sanders Barry C. 
Published: November 2003

AbstractWe present a numerical analysis of the performance of three‐dimensional (3D) perfectly matched layer (PML) absorbing boundary conditions (ABCs) in a photonic crystal (PC) waveguide. This formulation dramatically reduces the reflections from the ends of the PC waveguide, leading to highly accurate transmittance and reflectance calculations for waveguide components. The 3D PC‐based PML ABC is demonstrated to give good results when used to analyze a 90° bend in a 3D PC waveguide. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 1–3, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11268
Low‐loss microwave filters on CMOS‐grade standard silicon substrate with low‐k BCB dielectric
Authors: Leung Lydia L. W. , Chen Kevin J. , Huo Xiao , Chan Philip C. H. 
Published: November 2003

AbstractBenzocyclobutene (BCB), a low‐k, photosensitive, easily patterned material is used as the interfacing layer that isolates the passive components from the lossy, low‐resistivity silicon. Its performance is further improved by reducing the conductive loss with an electroplated and highly‐conductive metal, namely, copper. Standard 50‐Ω microstrip lines and a microstrip‐transmission‐line‐based microwave filter, exhibiting insertion losses of 0.8 dB and 1.1 dB at 10 GHz, respectively, are demonstrated. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 9–11, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11271
Modelling approaches to compare sorption and degradation of metsulfuron‐methyl in laboratory micro‐lysimeter and batch experiments
Authors: Heistermann Maik , Jene Bernhard , Fent Gunnar , Feyerabend Martin , Seppelt Ralf , Richter Otto , Kubiak Roland 
Published: November 2003

AbstractResults of laboratory batch studies often differ from those of outdoor lysimeter or field plot experiments—with respect to degradation as well as sorption. Laboratory micro‐lysimeters are a useful device for closing the gap between laboratory and field by both including relevant transport processes in undisturbed soil columns and allowing controlled boundary conditions. In this study, sorption and degradation of the herbicide metsulfuron‐methyl in a loamy silt soil were investigated by applying inverse modelling techniques to data sets from different experimental approaches under laboratory conditions at a temperature of 10 °C: first, batch‐degradation studies and, second, column experiments with undisturbed soil cores (28 cm length × 21 cm diameter). The column experiments included leachate and soil profile analysis at two different run times. A sequential extraction method was applied in both study parts in order to determine different binding states of the test item within the soil. Data were modelled using ModelMaker and Hydrus‐1D/2D.Metsulfuron‐methyl half‐life in the batch‐experiments (t1/2 = 66 days) was shown to be about four times higher than in the micro‐lysimeter studies (t1/2 about 17 days). Kinetic sorption was found to be a significant process both in batch and column experiments. Applying the one‐rate‐two‐site kinetic sorption model to the sequential extraction data, it was possible to associate the stronger bonded fraction of metsulfuron‐methyl with its kinetically sorbed fraction in the model. Although the columns exhibited strong significance of multi‐domain flow (soil heterogeneity), the comparison between bromide and metsulfuron‐methyl leaching and profile data showed clear evidence for kinetic sorption effects. The use of soil profile data had significant impact on parameter estimates concerning sorption and degradation. The simulated leaching of metsulfuron‐methyl as it resulted from parameter estimation was shown to decrease when soil profile data were considered in the parameter estimation procedure. Moreover, it was shown that the significance of kinetic sorption can only be demonstrated by the additional use of soil profile data in parameter estimation. Thus, the exclusive use of efflux data from leaching experiments at any scale can lead to fundamental misunderstandings of the underlying processes. Copyright © 2003 Society of Chemical Industry
Territorial behaviour and population dynamics in red grouse Lagopus lagopus scoticus. I. Population experiments
Authors: Mougeot François , Redpath Steve M. , Moss Robert , Matthiopoulos Jason , Hudson Peter J. 
Published: November 2003

Summary

According to the ‘territorial behaviour’ hypothesis, population cycles of red grouse are caused by delayed density‐dependent changes in the aggressiveness of territorial cocks. We report here on a replicated population experiment testing assumptions of this hypothesis.
We used testosterone implants to increase aggressiveness of cocks for 3 months during autumn, when recruitment and territory establishment take place. On two moors located in northern England, and on two 1‐km2 areas within each moor, we implanted adult cocks with testosterone on an experimental area and with sham implants on a control area.
During the first autumn, the testosterone treatment prevented recruitment of young cocks into the territorial populations. This reduced breeding density and altered the age ratio among territorial cocks, and possibly levels of kinship. If so, the ‘kinship’ hypothesis predicted that density and recruitment should continue to differ between testosterone‐treated and control areas.
Grouse density remained significantly lower on the experimental than on the control areas for two consecutive breeding seasons. This confirmed a strong spatial structuring within grouse populations, which prevented immigration from neighbouring higher‐density areas. In the second autumn, testosterone was not implanted but the recruitment rate remained significantly lower and cock density continued to decline more on the experimental than on the control areas.
The results suggest that cocks continued to be aggressive and to maintain large territories for at least a year after aggressiveness was increased experimentally, and therefore that autumn aggressiveness is influenced by previous territorial contests.
The experiment validates key assumptions of the ‘territorial behaviour’ hypothesis for red grouse cycles. Population models in a subsequent paper demonstrate how changes in aggressiveness can cause population cycles.
Acquisition of desiccation tolerance in developing wheat embryos correlates with appearance of a fluid phase in membranes
Authors: GOLOVINA E. A. , HOEKSTRA F. A. 
Published: November 2003

ABSTRACTMembrane behaviour in developing wheat (Triticum aestivum cv Priokskaya) embryos was studied in relation to the acquisition of desiccation tolerance, using spin probe techniques. Fresh embryos were able to develop into seedlings at day 15 after anthesis, but it took 18 d before fast‐dried, isolated embryos could germinate. On the basis of membrane integrity measurements it was estimated that between 14 and 18 d after anthesis the proportion of embryonic cells surviving fast drying increased and the critical moisture content, to which embryonic cells could be dehydrated, decreased. Apparently, embryonic cells do not acquire the same level of desiccation tolerance simultaneously. Only when all cells had become desiccation tolerant was germination of air‐dried embryos possible. Using 5‐doxylstearic acid as the probe molecule, an approximately similar lipid–water interface ordering of membranes was observed in all hydrated embryos, irrespective of age. Dehydration had a dual effect on the lipid interface: further ordering of the major part of the interface and the appearance of additional, disturbed regions. The proportion of these regions correlated with the proportion of desiccation‐tolerant cells. We propose that the membrane surface disturbance be caused by endogenous amphiphiles that partition from the cytoplasm into membranes during drying. The absence of such disturbed regions in dried, desiccation‐sensitive embryos might reflect a lack of sufficient amphiphiles. The relevance of membrane surface disturbance for desiccation tolerance is discussed.
Large‐scale identification of leaf senescence‐associated genes
Authors: Gepstein Shimon , Sabehi Gazalah , Carp Marie‐Jeanne , Hajouj Taleb , Nesher Mizied Falah Orna , Yariv Inbal , Dor Chen , Bassani Michal 
Published: November 2003

SummaryLeaf senescence is a form of programmed cell death, and is believed to involve preferential expression of a specific set of ‘senescence‐associated genes’ (SAGs). To decipher the molecular mechanisms and the predicted complex network of regulatory pathways involved in the senescence program, we have carried out a large‐scale gene identification study in a reference plant, Arabidopsis thaliana. Using suppression subtractive hybridization, we isolated approximately 800 cDNA clones representing SAGs expressed in senescing leaves. Differential expression was confirmed by Northern blot analysis for 130 non‐redundant genes. Over 70 of the identified genes have not previously been shown to participate in the senescence process. SAG‐encoded proteins are likely to participate in macromolecule degradation, detoxification of oxidative metabolites, induction of defense mechanisms, and signaling and regulatory events. Temporal expression profiles of selected genes displayed several distinct patterns, from expression at a very early stage, to the terminal phase of the senescence syndrome. Expression of some of the novel SAGs, in response to age, leaf detachment, darkness, and ethylene and cytokinin treatment was compared. The large repertoire of SAGs identified here provides global insights about regulatory, biochemical and cellular events occurring during leaf senescence.