bluuebunny/crossref_metadata_2025_split huggingface dataset:
On combined ring convolutional coded quantisation and CPM for joint source/channel coding
Authors: Lin Zihuai , Aulin Tor 
Published: April 2008

AbstractA new trellis‐based coded quantisation scheme using ring convolutional codes is presented. When it is combined with trellis‐coded continuous phase modulation (TCCPM) with convolutional codes over rings, a powerful joint source and channel coding (JSCC) scheme can be formed. We investigate the additive white Gaussian noise (AWGN) channel and the Rayleigh fading channel. Optimal soft decoding for the proposed JSCC scheme is studied. The soft decoder is based on the a posteriori probability (APP) algorithm for TCCPM with ring convolutional codes. It is shown that these systems with soft decoding outperform the same systems with hard decoding especially when the systems operate at low to medium signal‐to‐noise ratio (SNR). It is demonstrated that the new trellis quantisation schemes based on ring convolutional codes is superior to conventional trellis‐coded quantisation (TCQ) of the same complexity. The novelty of this work is in the development of a trellis‐based quantisation method using ring convolutional codes and the use of a soft decoder and the APP algorithm for the combined systems. Copyright © 2008 John Wiley & Sons, Ltd.
A multicommodity model of futures prices: Using futures prices of one commodity to estimate the stochastic process of another
Authors: Cortazar Gonzalo , Milla Carlos , Severino Felipe 
Published: April 2008

AbstractThis article proposes a multicommodity model of futures prices of more than one commodity that allows the use of long‐maturity futures prices available for one commodity to estimate futures prices for the other. The model considers that commodity prices have common and commodity‐specific factors. A procedure for choosing the number of both types of unobservable‐Gaussian factors is presented. Also, it is shown how commodities with and without seasonality may be jointly modeled and how to estimate the model using Kalman filter. Results for the West Texas Intermediate–Brent and for the West Texas Intermediate–unleaded gasoline models presented show strong improvements over the traditional individual‐commodity models, with much lower out‐of‐sample errors and better volatility estimates, even when using fewer factors. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:537–560, 2008
Identification of genomic changes associated with cisplatin resistance in testicular germ cell tumor cell lines
Authors: Noel Elodie E. , Perry Jackie , Chaplin Tracy , Mao Xueying , Cazier Jean‐Baptiste , Joel Simon P. , Oliver R. Tim D. , Young Bryan D. , Lu Yong‐Jie 
Published: April 2008

AbstractSince the introduction of cisplatin into the clinic, the treatment of patients with a variety of solid tumors including testicular germ cell tumors, ovarian and lung cancers, has dramatically improved. One of the main causes for therapeutic failure in these malignancies is the development of drug resistance. Testicular germ cell tumors (TGCTs), the most common malignancy in young men, exhibit extreme sensitivity to cisplatin‐based chemotherapy, making them an ideal model for investigating the mechanisms of cisplatin chemo‐sensitivity and resistance. TGCT development and pathogenesis have been well studied but little is known about the genetic background in chemo‐resistant cases. We investigated genomic differences between three TGCT parental cell lines and their cisplatin resistant derivatives. Using 10K single nucleotide polymorphism (SNP) microarray analysis, we identified two small chromosomal regions with consistent copy number changes across all three pairs of resistant cell lines. These were an 8.7 Mb region at 6q26‐27, which displayed consistent copy number gain and a 0.3 Mb deletion involving 4 SNPs at 10p14. Both the chromosomal gain and loss were confirmed by fluorescence in situ hybridization. The significance of these regions should be further investigated as they may contain key genes involved in the development of chemo‐ resistance to cisplatin‐based treatment in TGCTs and other cancers. © 2008 Wiley‐Liss, Inc.
Concomitant activation of Wnt pathway and loss of mismatch repair function in human melanoma
Authors: Castiglia Daniele , Bernardini Silvia , Alvino Ester , Pagani Elena , De Luca Naomi , Falcinelli Sabrina , Pacchiarotti Alberto , Bonmassar Enzo , Zambruno Giovanna , D'Atri Stefania 
Published: April 2008

AbstractConstitutive activation of the Wnt pathway plays a key role in the development of colorectal cancer and has also been implicated in the pathogenesis of other malignancies. Deregulation of Wnt signaling mainly occurs through genetic alterations of APC, the β‐catenin gene (CTNNB1), AXIN1 and AXIN2, leading to stabilization of β‐catenin. Physiologically, AXIN2 is transcriptionally induced on Wnt signaling activation and acts as a negative feedback regulator of the pathway. In colorectal cancer, mutations in CTNNB1 and AXIN2 occur preferentially in tumors with inactivation of the mismatch repair (MMR) genes MSH2, MLH1, or PMS2. In this study, the expression of β‐catenin and AXIN2, and the mutational status of CTNNB1, APC, and AXIN2 were evaluated in two MMR‐deficient (PR‐Mel and MR‐Mel) and seven MMR‐proficient human melanoma cell lines. Only PR‐Mel and MR‐Mel cells showed nuclear accumulation of β‐catenin and expression of the AXIN2 gene, and hence, constitutive activation of Wnt signaling. Mutational analysis identified a somatic heterozygous missense mutation in CTNNB1 exon three and a germline heterozygous deletion within AXIN2 exon seven in PR‐Mel cells, and a somatic biallelic deletion within APC in MR‐Mel cells. Deregulation of Wnt signaling and a defective MMR system were also present in the original tumor of PR and MR patients. Thus, we describe additional melanomas with mutations in CTNNB1 and APC, identify for the first time a germline AXIN2 mutation in a melanoma patient and suggest that inactivation of the MMR system and deregulation of the Wnt/β‐catenin signaling pathway cooperate to promote melanoma development and/or progression. © 2008 Wiley‐Liss, Inc.
Predicting river width, depth and velocity at ungauged sites in England and Wales using multilevel models
Authors: Booker D. J. , Dunbar M. J. 
Published: April 2008

AbstractUsing a dataset of gauged river discharges taken from sites in England and Wales, linear multilevel models (also known as mixed effects models) were applied to quantify the variability in discharge and the discharge‐hydraulic geometry relationships across three nested spatial scales. A jackknifing procedure was used to test the ability of the multilevel models to predict hydraulic geometry, and therefore width, mean depth and mean velocity, at ungauged stations. These models provide a framework for making predictions of hydraulic geometry parameters, with associated levels of uncertainty, using different levels of data availability. Results indicate that as one travels downstream along a river there is greater variability in hydraulic geometry than is the case between rivers of similar sizes. This indicates that hydraulic geometry (and therefore hydrology) is driven by catchment area, to a greater extent than by natural geomorphological variations in the streamwise direction at the mesoscale, but these geomorphological variations can still have a major impact on channel structure. Copyright © 2008 John Wiley & Sons, Ltd.
Assessment of annual high‐water events for the Mackenzie River basin, Canada
Authors: de Rham Laurent P. , Prowse Terry D. , Beltaos Spyros , Lacroix Martin P. 
Published: April 2008

AbstractRiver ice break‐up is known to have important morphological, ecological and socio‐economic effects on cold‐regions river environments. One of the most persistent effects of the spring break‐up period is the occurrence of high‐water events. A return‐period assessment of maximum annual nominal water depths occurring during the spring break‐up and open‐water season at 28 Water Survey of Canada hydrometric sites over the 1913–2002 time period in the Mackenzie River basin is presented. For the return periods assessed, 13 (14) stations are dominated by peak events occurring during the spring break‐up (open‐water) season. One location is determined to have a mixed signal. A regime classification is proposed to separate ice‐ and open‐water dominated systems. As part of the regime classification procedure, specific characteristics of return‐period patterns including alignment, and difference between the 2 and 10‐year events are used to identify regime types. A dimensionless stage‐discharge plot allows for a contrast of the relative magnitudes of flows required to generate maximum nominal water‐depth events in the different regimes. At sites where discharge during the spring break‐up is approximately one‐quarter or greater than the magnitude of the peak annual discharge, nominal water depths can be expected to exceed those occurring during the peak annual discharge event. Several physical factors (location, basin area, stream order, gradient, river orientation, and climate) are considered to explain the differing regimes and discussed relative to the major sub‐regions of the MRB. Copyright © 2008 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.
Regulation of adult human mesenchymal stem cells into osteogenic and chondrogenic lineages by different bioreactor systems
Authors: Wang Tzu‐Wei , Wu Hsi‐Chin , Wang Hsin‐Yen , Lin Feng‐Huei , Sun Jui‐Sheng 
Published: April 2008

AbstractThe aim of this study was to examine the feasibility of expanding and regulating mesenchymal stem cells (MSCs) from isolated adult human bone marrow mononuclear cells, seeded on gelatin–hyaluronic acid biomatrices, and then to quantitatively compare the gene expression in three different culture systems. Individual and interactive effects of model system parameters on construct structure, function, and molecular properties were evaluated. The results showed that these adult human MSCs even at old age not only expressed primitive mesenchymal cell markers but also maintained a high level of colony‐forming efficiency and were capable of differentiating into osteoblasts, chondrocytes, and adipocytes upon appropriate inductions. After 21 days of culture, we found that the osteoblastic and chondrocytic lineage gene expression were earlier and higher expressed in spinner flask bioreactor culture group when compared with the static culture and rotating wall vessel reactor culture. The osteogenic lineage proteins type I collagen, alkaline phosphatase, and osteocalcin were strongly stained in histological sections of spinner flask bioreactor culture, whereas these were less detected in the other two groups, especially in rotating wall vessel reactor culture. As for the markers associated with the chondrogenic lineage differentiation proteins, type II collagen was apparently expressed in spinner flask culture group, while the expression of proteoglycans (aggreacan, decorin) in three culture conditions took the lead of each other. We conclude that the spinner flask bioreactor with appropriate induction medium reported in this study may be used to rapidly expand adult MSCs and is likely to possess better induction results toward osteoblastic and chondrocytic lineages. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Photoreversibility and photostability in films of octopus rhodopsin isolated from octopus photoreceptor membranes
Authors: Paternolli Cristina , Neebe Martin , Stura Enrico , Barbieri Francesca , Ghisellini Paola , Hampp Norbert , Nicolini Claudio 
Published: April 2008

AbstractIn this work, a new biomaterial resulting from the isolation of octopus rhodopsin (OR) starting from octopus photoreceptor membranes is presented. Mass spectroscopic characterization was employed in order to verify the presence of rhodopsin in the extract. Photoreversibility and photochromic properties were investigated using spectrophotometric measurements and pulsed light. Thin films of OR were realized using the gel‐matrix entrapment method in polyvinyl alcohol solution. The results indicate that the photoreversibility and the photostability of the OR in gel‐matrices are maintained. Several measurements were performed to test the stability of the resulting biomaterial in time and at room temperature. Preliminary tests demonstrate that the photoreversibility and the photostability are still found after few days from the biomaterial preparation and after the exposure for several hours at room temperature. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Biodegradable fumarate‐based drug‐delivery systems for ophthalmic applications
Authors: Hacker M. C. , Haesslein A. , Ueda H. , Foster W. J. , Garcia C. A. , Ammon D. M. , Borazjani R. N. , Kunzler J. F. , Salamone J. C. , Mikos A. G. 
Published: April 2008

AbstractThe function of a photocrosslinked poly(propylene fumarate) (PPF)/poly(N‐vinyl pyrrolidone) (PVP) matrix for the sustained release of three ophthalmic model drugs, acetazolamide (AZ), dichlorphenamide (DP), and timolol maleate (TM), was investigated. The drugs differ in molecular weight and degree of dissociation in aqueous environments; both are parameters that significantly influence drug diffusivity. AZ, DP, and TM‐loaded cylindrical rods (10 mm length, 0.6 mm diameter) were fabricated by photoinduced cross‐copolymerization of PPF and N‐vinyl pyrrolidone (NVP) in molds. The released amounts of AZ, DP, TM, and NVP were determined by high‐performance liquid chromatography (HPLC). The effects of drug properties and loading on the release kinetics were investigated. The in vitro release of AZ, DP, and TM was well sustained from the polymer matrices over a period of ∼210, 270, and 250 days, respectively. The release kinetics correlated with the HPLC retention profiles of the different drugs. Following a small initial burst release (<10%), a dual modality release controlled by diffusion and bulk erosion was found for all drugs. Drug release rates of up to 4 μg/day were reached. Matrix drug loading generally affected the extent of the burst release, release kinetics, as well as the matrix water content and matrix degradation that were determined gravimetrically. Microcomputed tomography was used to image structural and dimensional changes of the devices. A preliminary rabbit implantation study revealed promising ocular biocompatibility of drug‐free PPF/PVP matrices. All results indicate the potential of photocrosslinked PPF‐based matrices as polymeric carriers for long‐term ophthalmic drug delivery. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Rheological, microstructural, and in vitro characterization of hybrid chitosan‐polylactic acid/hydroxyapatite composites
Authors: Araújo A. B. A. , Lemos A. F. , Ferreira J. M. F. 
Published: April 2008

AbstractIn this work, hybrid chitosan/hydroxyapatite composites material were developed and characterized. The polymer matrix was first dissolved in polylactic acid, and then hydroxyapatite (HA) was added as filler material. The effects of the added amounts of a crosslinking agent (genipin) and of the concentrations of lactic acid, and of the presence of HA powder on the evolution of rheological properties were evaluated. A significant decrease of gelation time with increasing amounts of crosslinking agent was observed, the effect being even more pronounced in the presence of HA. The chitosan matrix and the composites with a chitosan/HA weight ratio of 2/5 were characterized using microstructural analysis and in vitro tests. The formation of large pore sizes in the chitosan‐based scaffolds was favored by low concentrations of lactic acid and genipin. The in vitro tests in synthetic body fluid revealed an extensive formation of an apatitic layer onto the surface of the chitosan/HA composite scaffolds crosslinked with genipin. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Preparation and cytocompatibility of PLGA scaffolds with controllable fiber morphology and diameter using electrospinning method
Authors: Zhao Li , He Chenguang , Gao Yongjuan , Cen Lian , Cui Lei , Cao Yilin 
Published: April 2008

AbstractPoly(lactide‐co‐glycolide) (PLGA) scaffolds prepared by the electrospinning technology were paid more attention in tissue engineering, but detailed investigation on the influence of process parameters on scaffold morphology and fiber diameters as well as distribution remains to be conducted. In the current study, PLGA concentration, electric field strength, and feeding rate were varied to prepare different PLGA scaffolds. It was shown that with the varying of the above parameters, the electrospun porous PLGA scaffolds exhibited fibrous morphology either with/out beads or bead‐fiber string. The diameter of nanofibers increased with the PLGA concentration and feeding rate, whereas the electric field strength exerted only minor effects on the average diameter of the nanofibers. The cytocompatibility of the scaffold prepared from optimizing fabrication parameters was evaluated using human fibroblasts. Good cell attachment, fast proliferation rate, characteristic fibroblast morphology with homogeneous distribution was observed on the scaffold. As a whole, this study demonstrated that the fiber morphology and diameter of the electrospun PLGA scaffolds could be tailored by controlling fabrication parameters. And nanofibrous PLGA could act as a biologically preferred scaffold for fibroblasts growth with maintenance of characteristic morphology. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Spatiotemporal dynamics of regulatory protein recruitment at DNA damage sites
Authors: Mortusewicz Oliver , Leonhardt Heinrich , Cardoso M. Cristina 
Published: April 2008

AbstractMammalian cells are constantly threatened by multiple types of DNA lesions arising from various sources like irradiation, environmental agents, replication errors or by‐products of the normal cellular metabolism. If not readily detected and repaired these lesions can lead to cell death or to the transformation of cells giving rise to life‐threatening diseases like cancer. Multiple specialized repair pathways have evolved to preserve the genetic integrity of a cell. The increasing number of DNA damage sensors, checkpoint regulators, and repair factors identified in the numerous interconnected repair pathways raises the question of how DNA repair is coordinated. In the last decade, various methods have been developed that allow the induction of DNA lesions and subsequent real‐time analysis of repair factor assembly at DNA repair sites in living cells. This combination of biophysical and molecular cell biology methods has yielded interesting new insights into the order and kinetics of protein recruitment and identified regulatory sequences and selective loading platforms for the efficient restoration of the genetic and epigenetic integrity of mammalian cells. J. Cell. Biochem. 104: 1562–1569, 2008. © 2008 Wiley‐Liss, Inc.
2‐methoxyestradiol‐induced cell death in osteosarcoma cells is preceded by cell cycle arrest
Authors: Maran Avudaiappan , Shogren Kristen L. , Benedikt Michaela , Sarkar Gobinda , Turner Russell T. , Yaszemski Michael J. 
Published: April 2008

Abstract2‐Methoxyestradiol (2‐ME), a naturally occurring mammalian metabolite of 17β‐Estradiol (E2), induces cell death in osteosarcoma cells. To further understand the molecular mechanisms of action, we have investigated cell cycle progression in 2‐ME‐treated human osteosarcoma (MG63, SaOS‐2 and LM8) cells. At 5 µM, 2‐ME induced growth arrest by inducing a block in cell cycle; 2‐ME‐treatment resulted in 2‐fold increases in G1 phase cells and a decrease in S phase cells in MG63 and SaOS‐2 osteosarcoma cell lines, compared to the appropriate vehicle controls. 2‐ME‐treatment induced a threefold increase in the G2 phase in LM8 osteosarcoma cells. The results demonstrated steroid specificity, as the tumorigenic metabolite, 16α‐hydroxyestradiol (16‐OHE), did not have any effect on cell cycle progression in osteosarcoma cells. The cell cycle arrest coincided with an increase in expression of the cell cycle markers p21, p27 and p53 proteins in 2‐ME‐treated osteosarcoma cells. Also, MG63 cells, transiently transfected with cDNA for a ‘loss of function mutant’ RNA‐dependent protein kinase (PKR) protein, were resistant to 2‐ME‐induced cell cycle arrest. These results suggest that 2‐ME works in concert with factors regulating cell cycle progression, and cell cycle arrest precedes cell death in 2‐ME‐treated osteosarcoma cells. J. Cell. Biochem. 104: 1937–1945, 2008. © 2008 Wiley‐Liss, Inc.
Oxidation and nuclear localization of thioredoxin‐1 in sparse cell cultures
Authors: Spielberger Jeanine C. , Moody Amie D. , Watson Walter H. 
Published: April 2008

AbstractReactive oxygen species (ROS) were once viewed only as mediators of toxicity, but it is now recognized that they also contribute to redox signaling through oxidation of specific cysteine thiols on regulatory proteins. Cells in sparse cultures have increased ROS relative to confluent cultures, but it is not known whether protein redox states are affected under these conditions. The purpose of the present study was to determine whether culture conditions affect the redox state of thioredoxin‐1 (Trx1), the protein responsible for reducing most oxidized proteins in the cytoplasm and nucleus. The results showed that Trx1 was more oxidized in sparse HeLa cell cultures than in confluent cells. The glutathione pool was also more oxidized, demonstrating that both of the major cellular redox regulating systems were affected by culture density. In addition, the total amount of Trx1 protein was lower and the subcellular distribution of Trx1 was different in sparse cells. Trx1 in sparse cultures was predominantly nuclear whereas it was predominantly cytoplasmic in confluent cultures. This localization pattern was not unique to HeLa cells as it was also observed in A549, Cos‐1 and HEK293 cells. These findings demonstrate that Trx1 is subject to changes in expression, redox state and subcellular localization with changing culture density, indicating that the redox environments of the cytoplasm and the nucleus are distinct and have different requirements under different culture conditions. J. Cell. Biochem. 104: 1879–1889, 2008. © 2008 Wiley‐Liss, Inc.