bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHEK2 variant I157T may be associated with increased breast cancer risk
Authors: Kilpivaara Outi , Vahteristo Pia , Falck Jacob , Syrjäkoski Kirsi , Eerola Hannaleena , Easton Douglas , Bartkova Jirina , Lukas Jiri , Heikkilä Päivi , Aittomäki Kristiina , Holli Kaija , Blomqvist Carl , Kallioniemi Olli‐Pekka , Bartek Jiri , Nevanlinna Heli 
Published: May 2004

AbstractCell cycle checkpoint kinase 2 (CHEK2) is a transducer of cellular responses to DNA damage. The CHEK2 1100delC has previously been shown to be a low‐penetrance breast cancer susceptibility allele. We have evaluated the role of another CHEK2 variant, I157T in the FHA domain of the gene, for association with breast cancer. I157T was found at a significantly higher frequency in the population‐based series of breast cancer patients (77/1035, 7.4%, odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.06–1.95, p = 0.021) than among population controls (100/1885, 5.3%). The frequency in the familial breast cancer patients was not elevated (28/507, 5.5%, OR = 1.04, 95% CI = 0.68–1.61). The I157T protein, that undermines cellular responses to ionizing radiation and shows deficiency in substrate recognition in vivo, was expressed at normal level in tumor tissues as well as in cultured cells. The I157T protein was stable and it dimerized with the wild‐type CHEK2 co‐expressed in human cells. These functional properties of the I157T protein suggest that this variant may have negative effect on the pool of normal CHEK2 protein in heterozygous carrier cells by formation of heterodimers with wild‐type CHEK2. The I157T variant may be associated with breast cancer risk, but the risk is lower than for 1100delC. © 2004 Wiley‐Liss, Inc.
Overexpression of caveolin‐1 induces alteration of multidrug resistance in Hs578T breast adenocarcinoma cells
Authors: Cai Chuanxi , Chen Jianwen 
Published: May 2004

AbstractCaveolin‐1 is a major caveolae‐coat protein involved in a variety of cell signaling processes. Some studies have suggested that the level of caveolin‐1 expression positively correlates with multi‐drug resistance in cancer cells. We demonstrated for the first time that Hs578T doxorubicin resistant cells (Hs578T/Doxo), which contain low levels of endogenous caveolin‐1 and high levels of P‐glycoprotein, are rendered drug‐sensitive by overexpression of exogenous caveolin‐1. MTT assays showed that after overexpressing caveolin‐1, the drug resistance of Hs578T/Doxo cells to doxorubicin and cisplatin was reduced from 25.4 ± 1.5 and 65.3 ± 2.5 μg/ml to 0.8 ± 0.15 and 23.2 ± 2.1 μg/ml, respectively (i.e. reduced by 97% and 64%, respectively). Furthermore, using rhodamine‐123 efflux assays, we observed a significant decrease in P‐glycoprotein activity in caveolin‐1 overexpressing cells, similar to that observed with 5 μM cyclosporine A or 10 μM verapamil, 2 inhibitors of P‐glycoprotein activity. Using confocal microscopy, subcellular fractionation and co‐immunoprecipitation assays, a possible physical interaction between caveolin‐1 and P‐glycoprotein in the caveolae membrane was observed in Hs578T/Doxo cells overexpressing caveolin‐1. These results suggest that overexpression of caveolin‐1 changes the state of the cells from drug‐resistant to drug‐sensitive by inhibiting P‐glycoprotein transport activity. © 2004 Wiley‐Liss, Inc.
Bone formation in polymeric scaffolds evaluated by proton magnetic resonance microscopy and X‐ray microtomography
Authors: Washburn Newell R. , Weir Michael , Anderson Paul , Potter Kimberlee 
Published: May 2004

AbstractMagnetic resonance microscopy (MRM) and X‐ray microtomography (XMT) were used to investigate de novo bone formation in porous poly(ethyl methacrylate) (PEMA) scaffolds, prepared by a novel co‐extrusion process. PEMA scaffolds were seeded with primary chick calvarial osteoblasts and cultured under static conditions for up to 8 weeks. Bone formation within porous PEMA scaffolds was confirmed by the application of histologic stains to intact PEMA disks. Disks were treated with Alizarin red to visualize calcium deposits and with Sirius red to visualize regions of collagen deposition. DNA analysis confirmed that cells reached confluence on the scaffolds after 7 weeks in static culture. The formation of bone in PEMA scaffolds was investigated with water proton MRM. Quantitative MRM maps of the magnetization transfer ratio (MTR) yielded maps of protein deposition, and magnetic resonance (MR) relaxation times (T1 and T2) yielded maps of mineral deposition. The location of newly formed bone and local mineral concentrations were confirmed by XMT. By comparing MRM and XMT data from selected regions‐of‐interest in one sample, the inverse relationship between the MR relaxation times and mineral concentration was validated, and calibration curves for estimating the mineral content of cell‐seeded PEMA scaffolds from quantitative MRM images were developed. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 738–747, 2004
The effect of production regime and crucible materials on the thermal properties of sodium phosphate glasses produced from salts
Authors: Parsons A.J. , Burling L.D. , Rudd C.D. , Scotchford C.A. , Walker G.S. 
Published: May 2004

AbstractChanges in the thermal properties of sodium phosphate glasses during melt production have been investigated using Pt/Au and fused alumina crucibles. Glasses were produced from NaH2PO4 as a starting material, providing an intrinsic Na2O:P2O5 ratio of 1:1 and giving an O/P = 3, that is, a metaphosphate. In Pt/Au crucibles, glass transition temperatures rose to a plateau value of 295°C at a rate determined by melt temperature. No contamination of the glass by platinum or gold was detected or indicated in the results. Ea for the reaction was found to be 66.4 kJ mol−1. In fused alumina crucibles, glass transition temperatures rose to over 450°C, with these values showing some convergence at higher furnace temperatures. Extensive erosion of the alumina crucibles was observed. The amount of alumina incorporation within the glasses correlated well with the rise in glass transition temperature up to a maximum of 15.5 mol % Al2O3 content. Al2O3 incorporation above this value caused a reduction in the value of the Tg. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 22–29, 2004
Three‐dimensional topographic scanning electron microscope and Raman spectroscopic analyses of the irradiation effect on teeth by Nd:YAG, Er: YAG, and CO2 lasers
Authors: Yamada Magda K. , Uo Motohiro , Ohkawa Shoji , Akasaka Tsukasa , Watari Fumio 
Published: May 2004

AbstractA three‐dimensional analyzer installed in a scanning electron microscope was used to evaluate the morphology and surface roughness using noncontact profilometry. Observations were carried out on the enamel and dentin surface irradiated by three different lasers: Nd:YAG (wavelength 1.06 μm), Er:YAG (2.94 μm), and CO2 (10.6 μm). Spectroscopic analysis was done by Raman spectroscopy for nonirradiated and laser‐irradiated surfaces. The lasers were applied perpendicularly to vertically sectioned and polished human extracted caries‐free molars. The tooth was sectioned at each cavity for cross‐section analysis after laser irradiation. Irradiation by Nd:YAG and CO2 lasers of the enamel surface showed an opaque white color, different from dentin where the surface turned black. The Er:YAG laser induced no changes in color of the dentin. Numerous cracks associated with thermal stress were observed in the CO2 laser‐irradiated dentin. Noncontact surface profile analysis of Er:YAG laser‐irradiated enamel and dentin showed the deepest cavities, and direct cross‐sectional observations of them showed similar cavity outlines. The CO2 laser‐irradiated dentin had the least surface roughness. Raman spectroscopic analysis showed that fluorescence from the laser‐irradiated tooth was generally greater than from nonirradiated teeth. Bands in dentin attributed to organic collagen matrix were lost after Nd:YAG and CO2 laser irradiation, and a broad peak due to amorphous carbon appeared. The Er:YAG laser‐irradiated dentin showed no sign of a carbon band and had more suitable results for dental ablation. Noncontact surface profile analysis was effective to evaluate the structural change in the tooth in the microarea of study after laser irradiation. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 7–15, 2004
Human microvascular endothelial cell prostaglandin E1 synthesis during in vitro ischemia–reperfusion
Authors: Watkins Michael T. , Al‐Badawi Hassan , Russo Andrea L. , Soler Hiram , Peterson Brian , Patton George M. 
Published: May 2004

AbstractIschemia–reperfusion injury is a microvascular event documented in numerous in vivo animal models. In animal models, prostaglandin and prostaglandin analogues have been found to ameliorate reperfusion injury. These studies were undertaken to evaluate human microvascular endothelial PGE1 synthesis during in vitro ischemia followed by reperfusion. Human (neonatal) microvascular endothelial cell (MEC) cultures (n = 6) were subjected to sequential 2 h periods of normoxia (20% O2), ischemia (1.5% O2), and reperfusion (20% O2). Prostaglandin E2 synthesis in conditioned media was determined by ELISA. Steady state levels of MEC prostaglandin H synthase (PGHS)‐1 and ‐2 mRNA were assessed at the end of each 2‐h period using RT‐PCR and a quantitative mRNA ELISA. MEC PGHS protein levels were analyzed using an ELISA. PGE1 release increased significantly during the initial 30 min of ischemia, but rapidly fell below normoxic levels by 90 and 120 min. During reperfusion, PGE1 release returned to normoxic levels at 30, 60, and 90 min, and exceeded normoxic levels at 120 min. PGHS‐1 mRNA levels were undetectable during all experimental conditions. PGHS‐2 mRNA levels were unchanged by ischemia, but were decreased by reperfusion. In contrast, PGHS‐2 protein levels increased 3‐fold during ischemia, and remained elevated during reperfusion. Human MEC do not express PGHS‐1 mRNA in vitro. Prolonged ischemia decreases MEC PGE1 synthesis, and stimulates increased PGHS‐2 protein levels without altering the steady state levels of COX‐2 mRNA. During reperfusion, increased PGHS‐2 protein levels persist and are associated with stimulated PGE2 secretion, despite relative decreases in PGHS‐2 mRNA. J. Cell. Biochem. 92: 472–480, 2004. Published 2004 Wiley‐Liss, Inc.
Secretions of MMP‐9 by soluble glucocorticoid‐induced tumor necrosis factor receptor (sGITR) mediated by protein kinase C (PKC)δ and phospholipase D (PLD) in murine macrophage
Authors: Lee Hee‐Sook , Park So‐Yun , Lee Hyeon Woo , Choi Hye‐Seon 
Published: May 2004

AbstractThe secretion of matrix metalloproteinase (MMP‐9) is stimulated by the glucocorticoid‐induced tumor necrosis factor receptor (GITR), a new tumor necrosis factor receptor (TNFR) family, in murine macrophages via an activation of protein kinase C (PKC)δ and phospholipase D (PLD). Secretions of MMP‐9 are stimulated by the phosphatidic acid (PA), a product of PLD activity and an inhibition of PA production by a 1‐propanol inhibited secretion of MMP‐9 by soluble GITR (sGITR). MMP‐9 is not secreted by diacylglycerol (DAG) and an inhibitor of PA phosphatase has no effect on the secretion induced by sGITR, indicating that PA is responsible for MMP‐9 secretion in murine macrophages. Our data indicates that sGITR‐induced activation of PKCδ and PLD increases MMP‐9 secretions in macrophages. © 2004 Wiley‐Liss, Inc.
Variability of the recent climate of eastern Africa
Authors: Schreck Carl J. , Semazzi Fredrick H. M. 
Published: May 2004

AbstractThe primary objective of this study is to investigate the recent variability of the eastern African climate. The region of interest is also known as the Greater Horn of Africa (GHA), and comprises the countries of Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Rwanda, Somalia, Sudan, Uganda, and Tanzania.The analysis was based primarily on the construction of empirical orthogonal functions (EOFs) of gauge rainfall data and on CPC Merged Analysis of Precipitation (CMAP) data, derived from a combination of rain‐gauge observations and satellite estimates. The investigation is based on the period 1961–2001 for the ‘short rains’ season of eastern Africa of October through to December. The EOF analysis was supplemented by projection of National Centers for Environmental Prediction wind data onto the rainfall eigenmodes to understand the rainfall–circulation relationships. Furthermore, correlation and composite analyses have been performed with the Climatic Research Unit globally averaged surface‐temperature time series to explore the potential relationship between the climate of eastern Africa and global warming.The most dominant mode of variability (EOF1) based on CMAP data over eastern Africa corresponds to El Niño–southern oscillation (ENSO) climate variability. It is associated with above‐normal rainfall amounts during the short rains throughout the entire region, except for Sudan. The corresponding anomalous low‐level circulation is dominated by easterly inflow from the Indian Ocean, and to a lesser extent the Congo tropical rain forest, into the positive rainfall anomaly region that extends across most of eastern Africa. The easterly inflow into eastern Africa is part of diffluent outflow from the maritime continent during the warm ENSO events. The second eastern African EOF (trend mode) is associated with decadal variability. In distinct contrast from the ENSO mode pattern, the trend mode is characterized by positive rainfall anomalies over the northern sector of eastern Africa and opposite conditions over the southern sector. This rainfall trend mode eluded detection in previous studies that did not include recent decades of data, because the signal was still relatively weak. The wind projection onto this mode indicates that the primary flow that feeds the positive anomaly region over the northern part of eastern Africa emanates primarily from the rainfall‐deficient southern region of eastern Africa and Sudan. Although we do not assign attribution of the trend mode to global warming (in part because of the relatively short period of analysis), the evidence, based on our results and previous studies, strongly suggests a potential connection. Copyright © 2004 Royal Meteorological Society.
Interannual variability of European extreme winter rainfall and links with mean large‐scale circulation
Authors: Haylock M. R. , Goodess C. M. 
Published: May 2004

AbstractDecember–February (DJF) extreme rainfall was analysed at 347 European stations for the period 1958–2000. Two indices of extreme rainfall were examined: the maximum number of consecutive dry days (CDD); and the number of days above the 1961–90 90th percentile of wet‐day amounts (R90N). A principal component analysis of CDD found six components that accounted for 52.4% of the total variance. Six components of DJF R90N were also retained that accounted for 39.1% of the total variance. The second component of R90N has a very significant trend and the factor loadings closely resemble the observed linear trend in this index, suggesting that the analysis has isolated the mode of variability causing the trend as a separate component. The principal components of the indices were correlated with surface and upper‐air observations over the North Atlantic. The best correlations were generally found to be with sea‐level pressure (SLP) observations. A separate canonical correlation analysis of each of the two indices with SLP revealed several coupled modes of variability. The North Atlantic oscillation (NAO) was isolated as the first canonical pattern for R90N. For CDD the first two canonical coefficients of CDD were significantly correlated with the NAO index. Generally, the canonical coefficients with the highest correlations with the NAO had the most significant trends, suggesting that the observed trend in the NAO has strongly contributed to the observed trends in the indices. Two other important canonical patterns were isolated: a pattern of anomalous mean SLP (MSLP) centred over the North Sea, which seems to be related to local sea‐surface temperature over this region; and a dipole‐like pattern of MSLP with poles over the eastern Mediterranean and the central North Atlantic. Repeating the canonical correlation analysis with two other indices of extreme rainfall, the 90th percentile of wet day amounts and the maximum 10 day rainfall total, gives very similar coupled patterns. Copyright © 2004 Royal Meteorological Society.
Monolithic systems: from separation science to heterogeneous catalysis
Authors: Lubbad Said , Mayr Betina , Mayr Monika , Buchmeiser M.R. 
Published: May 2004

AbstractRecent results that have been obtained in the ring‐opening metathesis polymerization (ROMP)‐based synthesis of monolithic supports are summarized. We have elaborated a synthetic concept that allows modifying monolithic supports in a way that they can be used both for applications in separation science, for SEC and as supports for catalytically active systems. In all cases, a tailor‐made microstructure was accessible due to the controlled character of the transition‐metal catalyzed polymerization. Taking advantage of the “living” catalytic sites, an “in situ” functionalization was accomplished by subsequently grafting a variety of functional monomers and catalyst precursors onto the rod. Their design and use as supports for high‐performance separation devices (e.g. for ds‐DNA) and catalytic supports (e.g. supported Grubbs‐type catalysts) is summarized.
Positron annihilation: a unique method for studying polymers
Authors: Dlubek Günter , Kilburn Duncan , Bondarenko Vladimir , Pionteck Jürgen , Krause‐Rehberg Reinhard , Alam M. Ashraf 
Published: May 2004

AbstractPositron annihilation is a unique technique for studying the local free volume of polymers. Employing the positron annihilation lifetime spectroscopy (PALS) the size and size distribution of subnanometer size holes which constitute the excess free volume may be studied. In combination with macroscopic volume data the fractional free volume and the number density of holes may be estimated. After presenting the principles of the method, some examples typically for the investigation of the free volume in polymers will be given. Moreover, the study of interdiffusion in demixed polymer blends and further applications are shortly reviewed
Sulphonated poly(ether ether ketone): synthesis and characterisation
Authors: Lakshmi V.V. , Choudhary V. , Varma I.K. 
Published: May 2004

AbstractThe paper describes the sulphonation of commercially available poly(ether ether ketone) PEEK (GATONETM, Gharda Chemicals Limited, India and VICTREX®, ICI Limited, UK) by using concentrated sulphuric acid. The concentration of GATONE in conc. H2SO4 was varied from 4‐10% (w/v) whereas in VICTREX® the concentration was 4% (w/v). The temperature was varied from 35‐55°C and the duration of reaction was 3‐7 h. Structural characterisation of sulphonated polymers was done by elemental analysis, FT‐IR and 1H‐NMR spectroscopy. On the basis of elemental analysis, the extent of sulphonation of GATONE was found to be 57‐75%. The extent of sulphonation as determined by 1H‐NMR in case of GATONE was in the range of 53‐80% and for VICTREX 58‐87%. Thermal analysis, proton conductivity and water uptake of these samples were also studied. Proton conductivity of the films was comparable to the perflourinated polymer (Nafion).
Reactivity of supramolecular systems based on calix[4]resorcinarene derivatives and surfactants in hydrolysis of phosphorus acid esters
Authors: Ryzhkina Irina S. , Pashirova Tat'yana N. , Habicher Wolf D. , Kudryavtseva Ludmila A. , Konovalov Alexander I. 
Published: May 2004

AbstractThe formation of mixed micelles of amphiphilic calix[4]resorcinarenes with aminomethyl (AMC, PAMC), tris(hydroxymethyl)amide (THAC) fragments and the cationic surfactant cetyl trimethylammonium bromide (CTAB) in water and aqueous DMF solutions (10‐50% DMF) leads to the decrease of the critical micelle concentration of the systems and the increase of the size of the mixed micelles in comparison with CTAB micelles. The catalytic activity of the mixed systems in the hydrolysis of phosphorus acid esters is higher than those of CTAB micelle and AMC, PAMC or THAC aggregates.
Heterotelechelic poly(oxazolidine‐acetals) and their functionalization
Authors: Maślińska‐Solich Jolanta , Gibas Edyta 
Published: May 2004

AbstractTelechelic poly(1,3‐oxazolidine‐acetal)s with ‐CH2OH and ‐CHO groups were synthesized by polycondensation of the 2‐amino‐2‐hydroxy‐1,3‐propanediol (1) (TRIS) with terephthaldehyde (2). The degree of polymerization (DP) was controlled by the ratio of 1 to 2 at the given reaction time. Characterization was achieved by 1H and 13C NMR and IR spectroscopy. The distribution of oxazolidine‐acetal units in the polymer chain has been performed using ESI‐MS. The activities of telechelic poly(oxazolidine‐acetal) were determined in reaction oxidation (4‐chloroperbenzoic acid), reduction (CH3MgCl) and nucleophilic substitution (acylation, alkylation).
Synthesis of functional polymers with acetal‐monosaccharide moieties
Authors: Maślińska‐Solich Jolanta , Kukowka Sylwia 
Published: May 2004

AbstractThe polycondensation of methyl α‐D‐mannopyranoside (1) with 1,n‐bis(formylphenoxy)alkanes (2), using acidic catalysts, leads to the formation of linear polymers and macrocyclic compounds. The structure of the polymer and macrocycles was determined by 1H, 13C NMR spectroscopy and ESI‐MS analysis.
ω‐substituted long chain alkylphosphonic acids – their synthesis and deposition on metal oxides and subsequent functional group conversion of the deposited compounds
Authors: Eschner Michael , Frenzel Ralf , Simon Frank , Pleul Dieter , Uhlmann Petra , Adler Hans‐Jürgen 
Published: May 2004

AbstractThe crystal structure and the surface of alumina layers on silicon wafers were investigated by means of GIWAXS, WAXS, and AFM. Self‐assembled monolayers of ω‐substituted long‐chain alkylphosphonic acids were deposited on alumina and the layer thickness and homogeneity were determined by ellipsometry revealing a dependency of thickness and homogeneity on the nature of the substituent. During the adsorption process surface etching by the phosphonic acid was observed causing an increase in surface roughness.Furthermore, ex post functional group conversions were carried out yielding surface bound azides and rhodanides.
Reactive polymers on the basis of functional peroxides
Authors: Fleychuk R.I. , Kohut A.M. , Hevus O.I. , Voronov S. 
Published: May 2004

AbstractThe copolymerization constants of new monomer containing ditertiary peroxide groups with styrene have been determined. The peroxide monomers were prepared by the acylation of 3‐(tert‐butylperoxy)‐3‐methyl‐1‐butanol with methacryloyl chloride or maleic anhydride in the presence of tertiary amines. Peroxide containing copolymers were obtained by copolymerization of peroxyalkyl methacrylate and peroxyalkyl maleate with styrene.
Ring‐expansion polycondensation of 2‐stanna‐1,3‐dioxepane (or 1,3‐dioxepene) with dicarboxylic acid chlorides
Authors: Kricheldorf Hans R. , Chatti Saber , Schwarz Gert 
Published: May 2004

Abstract2,2‐Dibutyl‐2‐stanna‐1,3‐dioxepane 1 (or 1,3‐dioxepene 2) were prepared from 1,4‐butane (or 1,4‐butene) diol and dibutyltin dimethoxide. They were polycondensed at 80°C in n‐heptane with adipoyl‐, suberoyl, sabacoyl chloride and with decane‐1,10‐dicarbonyl chloride. In the case of suberoyl chloride and 2,2‐dibutyl‐2‐stanna‐1,3‐dioxepane reaction time, temperature and stoichiometry were varied to optimize both the molecular weight and the fraction of cyclic polyesters. With a slight excess of the dicarboxylic acid chlorides, only macrocyclic polyesters were obtained in all cases. The resulting cyclic polyesters were characterized by viscosity measurements, by 1H and 13C NMR and by MALDI‐TOF mass spectrometry.