bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of collagen structure on matrix trafficking by human fibroblasts
Authors: Abraham Leah C. , Vorrasi John , Kaplan David L. 
Published: May 2004

AbstractBiodegradation of collagen biomaterial matrices and the deposition of new collagen extracellular matrix (ECM) are critical to the integration of in vitro bioengineered materials and tissues in vivo. In previous studies, we observed significant impact of collagen matrix structure on primary lung fibroblast behavior in vitro. In the present work, to begin to understand the mechanistic basis for our previous observation, the response of human fibroblasts (IMR‐90) to the structural state of collagen matrices was studied with respect to cell proliferation, cell morphology, β‐galactosidase level, and transcript content for collagen (Col‐1), matrix metalloproteinases (MMP‐1, MMP‐2), tissue inhibitors of matrix metalloproteinase (TIMP‐1 and TIMP‐2). Collagen digestion was assessed quantitatively by uptake of collagen‐coated fluorescent beads incorporated in the preformed collagen matrix. Transcript levels related to the deposition of new ECM proteins varied as a function of the structure of the collagen matrix presented to the cells. Col‐1 expression was 2‐fold higher and expression for MMP‐1, MMP‐2, TIMP‐1, and TIMP‐2 increased for cells when grown on 156 μg/cm2 denatured collagen compared with cells grown on tissue culture (TC) plastic. On 156 μg/cm2 nondenatured (native) collagen, Col‐1 expression was decreased by half and MMP‐2 was increased by 2.5‐fold compared with cells grown on TC plastic. On 78 μg/cm2 denatured collagen, Col‐1 expression was 80% whereas the MMPs and TIMPs were increased by 1.25‐ to 2‐fold compared with cells grown on TC plastic. On 78 μg/cm2 nondenatured collagen expression of all 5 transcripts was reduced 60‐90% of the levels determined for the cells grown on TC plastic. Cell viability, based on cell morphology and β‐galactosidase activity, was improved on the denatured collagen. A higher level of collagen matrix incorporation was observed for cells grown on denatured collagen than on nondenatured collagen or TC plastic. These data suggest that tissue engineering matrices incorporating denatured collagen may promote more active remodeling toward new ECM in comparison to cells grown on nondenatured collagen or cells grown on TC plastic. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 39–48, 2004
A new austenitic stainless steel with a negligible amount of nickel: An in vitro study in view of its clinical application in osteoporotic bone
Authors: Fini M. , Giavaresi G. , Giardino R. , Lenger H. , Bernauer J. , Rimondini L. , Torricelli P. , Borsari V. , Chiusoli L. , Chiesa R. , Cigada A. 
Published: May 2004

AbstractA biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni (<0.20%). In previous in vitro and in vivo studies it was compared with conventional SS and Ti6Al4V and shown to be a promising material in orthopedics. Because osteoporosis is a type of pathology very often encountered in implanted patients and can be studied with in vitro models, the purpose of the present study was to evaluate P558 in vitro through comparison of normal (nOB) with osteopenic (oOB) bone‐derived primary rat osteoblasts. Osteoblasts were cultured directly on P558 and polystyrene as controls for 72 h. Osteoblast proliferation, adhesion, and activity (ALP, OC, TGF‐β1, and IL‐6) were evaluated at 24 and 72 h. Results demonstrated that the growth of nOB and oOB cultured on P558 was not affected negatively when compared to control. Cells on P558 did not show any alteration in terms of adhesion, proliferation, and metabolic marker production in nOB and oOB cultures, and a significant increase in ALP, OC, and TGF‐β1 production was observed. SEM images revealed no alteration in cell morphology. The current findings demonstrate that P558 promotes osteoblast proliferation, activation, and differentiation not only in normal bone, but also in osteopenic bone‐derived osteoblasts. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 30–37, 2004
Novel clusters of receptors for sphingosine‐1‐phosphate, sphingosylphosphorylcholine, and (lyso)‐phosphatidic acid: New receptors for “Old” ligands
Authors: Kostenis Evi 
Published: May 2004

AbstractThe (lyso)phospholipid mediators sphingosine‐1‐phosphate (S1P), lysophosphatidic acid (LPA), sphingosylphosphorylcholine (SPC), and phosphatidic acid (PA) regulate diverse cellular responses such as proliferation, survival and death, cytoskeletal rearrangements, cell motility, and differentiation among many others. Signaling is complex and many signaling events are mediated through the activation of cell surface seven transmembrane (7TM) G protein coupled receptors. Five high affinity receptors for S1P have been identified so far and named S1P1, 2 ,3 ,4 ,5 (formerly referred to as endothelial differentiation gene (edg)1, 5, 3, 6, 8). Recently, the orphan receptor GPR63 was identified a low affinity S1P receptor structurally distant from the S1P1–5 family. The orphan GPR3, 6, 12 cluster, phylogenetically related to the edg and melanocortin receptors appears to be subject to modulation by S1P and SPC although all three receptors are strong constitutive stimulators of the Gαs‐adenylyl cyclase (AC) pathway and would not require additional ligand stimulation but rather inverse agonism to control activity. Ovarian cancer G protein coupled receptor 1 (OGR1) and GPR4, two structurally closely related receptors were assigned in functional and binding studies as high affinity molecular targets for SPC. Very recently, however, both OGR1 and GPR4 were described as receptors endowed with the ability to signal cells in response to protons. LPA exerts its biological effects through the activation of G protein coupled LPA1–3 receptors (formerly referred to as edg2, 4, 7). A fourth high affinity LPA receptor has been identified: P2Y9 (GPR23) structurally related to nucleotide receptors and phylogenetically quite distant from the high affinity LPA1–3 cluster. This review attempts to give an overview about the existing families of lysophosholipid receptors and the spectrum of lipid agonists they use as high or low affinity ligands to relay extracellular signals into intracellular responses. Recently deorphaned lipid receptors, within and outside the known lipid receptor clusters will receive particular attention. © 2004 Wiley‐Liss, Inc.
G protein mediated signaling pathways in lysophospholipid induced cell proliferation and survival
Authors: Radeff‐Huang Julie , Seasholtz Tammy M. , Matteo Rosalia G. , Brown Joan Heller 
Published: May 2004

AbstractAgonist activation of a subset of G protein coupled receptors (GPCRs) stimulates cell proliferation, mimicking the better known effects of tyrosine kinase growth factors. Cell survival or apoptosis is also regulated via pathways initiated by stimulation of these same GPCRs. This review focuses on aspects of signaling by the lysophospholipid mediators, lysophosphatidic acid (LPA), and sphingosine 1 phosphate (S1P), which make these agonists uniquely capable of modulating cell growth and survival. The general features of GPCR coupling to specific G proteins, downstream effectors and signaling cascades are first reviewed. GPCR coupling to Gi and Ras/MAPK or to Gq and phospholipase generated second messengers are insufficient to regulate cell proliferation while G12/13/Rho engagement provides additional complementary signals required for cell proliferation. Survival is best predicted by coupling to Gi pathways that regulate PI3K and Akt, but other signals generated through different G protein pathways are also implicated. The unique ability of LPA and S1P to concomitantly stimulate Gi, Gq, and G12/13 pathways, given the proper complement of expressed LPA or S1P receptors, allows these receptors to support cell survival and proliferation. In pathophysiological situations, e.g., vascular disease, cancer, brain injury, and inflammation, components of the signaling cascade downstream of lysophospholipid receptors, in particular those involving Ras or Rho, may be altered. In addition, up or downregulation of LPA or S1P receptor subtypes, altering their ratio, and increased availability of the lysophospholipid ligands at sites of injury or inflammation, likely contribute to disease and may be important targets for therapeutic intervention. © 2004 Wiley‐Liss, Inc.
Vitamin D regulated keratinocyte differentiation
Authors: Bikle Daniel D. 
Published: May 2004

AbstractThe epidermis is the largest organ in the body. It is comprised primarily of keratinocytes which are arranged in layers that recapitulates their programmed life cycle. Proliferating keratinocytes are on the bottom—the stratum basale. As keratinocytes leave the stratum basale they begin to differentiate, culminating in the enucleated stratum corneum which has the major role of permeability barrier. Calcium and the active metabolite of vitamin D, 1,25(OH)2D3, play important roles in this differentiation process. The epidermis has a gardient of calcium with lowest concentrations in the stratum basale, and highest concentrations in the stratum granulosum where proteins critical for barrier function are produced. Vitamin D is made in different layers of the epidermis, but 1,25(OH)2D3 is made primarily in the stratum basale. Together calcium and 1,25(OH)2D3 regulate the ordered differentiation process by the sequential turning on and off the genes producing the elements required for differentiation as well as activating those enzymes involved in differentiation. Animal models in which the sensing mechanism for calcium, the receptor for 1,25(OH)2D3, or the enzyme producing 1,25(OH)2D3 have been rendered inoperative demonstrate the importance of these mechanisms for the differentiation process, although each animal model has its own phenotype. This review will examine the mechanisms by which calcium and 1,25(OH)2D3 interact to control epidermal differentiation. © 2004 Wiley‐Liss, Inc.
A group extensions approach to relative difference sets
Authors: Galati John C. 
Published: May 2004

AbstractA new approach to (normal) relative difference sets (RDSs) is presented and applied to give a new method for recursively constructing infinite families of semiregular RDSs. Our main result (Theorem 7.1) shows that any metabelian semiregular RDS gives rise to an infinite family of metabelian semiregular RDSs. The new method is applied to identify several new infinite families of non‐abelian semiregular RDSs, and new methods for constructing generalized Hadamard matrices are given. The techniques employed are derived from the general theory of group extensions. © 2004 Wiley Periodicals, Inc. J Combin Designs 12: 279–298, 2004.
Control of H2S waste gas emissions with a biological activated carbon filter
Authors: Chung Ying‐Chien , Lin Yu‐Yen , Tseng Ching‐Ping 
Published: May 2004

AbstractThe removal of high concentrations of H2S from waste gases containing mixtures of H2S and NH3 was studied using the pilot‐scale biofilter. Granular activated carbon (GAC), selected as support material in this study, demonstrated its high adsorption capacity for H2S and good gas distribution. Extensive tests to determine removal characteristics, removal efficiency, and removal capacity of high H2S levels and coexisting NH3 in the system were performed. In seeking the appropriate operating conditions, the response surface methodology (RSM) was employed. H2S removal capacities were evaluated by the inoculated bacteria (biological conversion) and BDST (Bed Depth Service Time) methods (physical adsorption). An average 98% removal efficiency for 0.083–0.167 mg dm−3 of H2S and 0.004–0.021 mg dm−3 of NH3 gases was achieved during the operational period because of rapid physical adsorption by GAC and subsequently an effective biological regeneration of GAC by inoculated Pseudomonas putida CH11 and Arthrobacter oxydans CH8. The results showed that H2S removal efficiency for the system was not affected by inlet NH3 concentrations. In addition, no acidification was observed in the BAC biofilter. High buffer capacity and low moisture demand were also advantages of this system. The maximal inlet loading and critical loading for the system were 18.9 and 7.7 g‐H2S m−3 h−1, respectively. The results of this study could be used as a guide for the further design and operation of industrial‐scale systems. Copyright © 2004 Society of Chemical Industry
Electrolytic recovery of zinc from zinc ash using a catalytic anode
Authors: Ramachandran P , Nandakumar V , Sathaiyan N 
Published: May 2004

AbstractThe process of galvanisation of steel generates zinc ash as the waste product, thus creating pollution problems. The recovery of zinc metal from zinc ash, with a zinc content of about 76% by leaching and electrowinning has been studied. The presence of chloride has been identified as the major problem area. A catalytic anode based on iridium dioxide (IrO2) was used as the anode material to overcome this problem. Catalyst loading was kept at an economically acceptable level. The catalyst's stability, energy consumption and efficiency of zinc recovery are discussed. The service life of the IrO2 active coating has been established by an accelerated polarisation test. The zinc deposit recovered from the zinc ash has been examined by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Copyright © 2004 Society of Chemical Industry
Influence of acid treatment on the surface activity and mass transfer inhibition of a splittable surfactant
Authors: Lee Yuh‐Lang , Lin Shi‐Yow 
Published: May 2004

AbstractA splittable surfactant, Triton SP‐190, was used to evaluate the effects of acid treatment on the mass transfer rate of an extraction process and on the interfacial tension‐lowering activity of a system containing this surfactant. Equilibrium and dynamic interfacial tensions at the interface of CCl4 and the aqueous phase containing surfactant were measured by using pendent drop tensiometry enhanced by video digitization. A single‐drop extraction apparatus was used to obtain the extraction percentage of acetic acid from the dispersed CCl4 droplets to the aqueous phase. The results indicate that the inorganic acid treatment can inhibit the dynamic and equilibrium interfacial tension‐lowering activity of Triton SP‐190. The mass transfer resistance induced by the addition of Triton SP‐190 can also be reduced by the pre‐treatment of acid. The effectiveness of acid treatment on both properties was greater at low pH values, lower surfactant concentrations, and longer treatment times. With HCl treatment, the equilibrium interfacial tension was not able to increase to the value of a surfactant‐free system, but approached a maximum value which was independent of the pH value, but dependent on surfactant concentration. On the contrary, the extraction percentage, which has decreased due to the presence of surfactant, can be recovered completely to that of a surfactant‐free system by acid treatment. The acid‐treatment time required to achieve a significant recovery of mass transfer rate was much longer than that required to recover the interfacial tension. The present results also demonstrate that the constituents contained in an acid‐treatment system had different effectiveness in affecting the interfacial tension and mass transfer rate due to the different mechanisms involved. Copyright © 2004 Society of Chemical Industry
Effect of pH and activated charcoal adsorption on hemicellulosic hydrolysate detoxification for xylitol production
Authors: Mussatto Solange I , Santos Júlio C , Roberto Inês C 
Published: May 2004

AbstractBiotechnological conversion of xylose into xylitol using hydrolysates obtained from the hemicellulosic fraction of lignocellulosic materials is compromised by the presence of compounds released or formed during the hydrolysis process, some of them being toxic to microorganisms. In order to improve the bioconversion of these hydrolysates it is necessary to find methods to reduce their toxicity. In the present work, rice straw hemicellulosic hydrolysate was treated by six different procedures (all of them involving pH adjustment, with or without activated charcoal adsorption), before being used as a fermentation medium for xylitol production. The most effective method of treatment was to increase the initial pH (0.4) to 2.0 using solid NaOH, followed by the addition of activated charcoal (25 g kg−1) and increase in the pH to 6.5 using solid NaOH. Lignin degradation products were the most inhibitory compounds present in the hydrolysate; their removal was selective and strongly dependent on the pH employed in the treatment. The highest yield of xylitol was 0.72 g g−1 xylose, with a productivity of 0.55 g dm−3 h−1. Copyright © 2004 Society of Chemical Industry
Transformation of 2,4‐dichlorophenoxy‐ethanoic acid (2,4‐D) by a photoassisted ferrous oxalate/H2O2 system
Authors: Kwan CY , Chu W 
Published: May 2004

AbstractThe kinetics of the dependence of pH, oxalate, and hydrogen peroxide concentrations on the degradation performance of the herbicide 2,4‐dichlorophenoxyethanoic acid (2,4‐D) was studied in a novel ferrous oxalate/H2O2/UV system. The formation and destruction of the primary intermediate, 2,4‐dichlorophenol (2,4‐DCP), was also monitored in the study. A rate enhancement of about 2.9 times was found when 1.2 mM of oxalate was added to the conventional Fe2+/H2O2/UV process. However, excess oxalate suppressed the reaction due to the scavenging and light attenuation effects. The 2,4‐D transformation at a lower initial pH was faster than that at a higher pH, and the different reaction mechanisms were investigated. In addition to the decay rates, the yield of the intermediate 2,4‐DCP was also affected by the initial solution pH. The increment of hydrogen peroxide concentration did not increase the initial decay rates of 2,4‐D, yet it improved the overall removal of 2,4‐D and elevated the formation of the corresponding intermediate (2,4‐DCP). Copyright © 2004 Society of Chemical Industry
Crises, setbacks and chronic problems—the determinants of economic stress events among poor households in India
Authors: Noponen Helzi , Kantor Paula 
Published: May 2004

AbstractThis study analyses the incidence, frequency, costs and subsequent coping strategies of economic stress events which disrupt the household economy among poor self‐employed women organized by SEWA, a grassroots development NGO. An analysis of the determinants of stress levels reveals that women who were members in SEWA for longer periods, who held savings accounts in SEWA Bank and who provided greater earnings share to total family income had fewer stresses. The analysis underscores the positive effect of programs in financial service, social security, co‐operative and trade union activities. The findings lend support to arguments in favour of the efficacy of credit‐plus rather than minimalist creict programmes for poor women. Copyright © 2004 John Wiley & Sons, Ltd.
Political and economic determinants of private investment
Authors: Le Quan V. 
Published: May 2004

AbstractThis paper presents empirical evidence that links private investment to rate of return differential, risk aversion, and several types of political and economic risk. Estimating private investment equation for a panel of 25 developing countries over 21 years yields the following results: (i) socio‐political instability characterized by nonviolent protests promotes private investment while violent uprisings hinder private investment; (ii) regime change instability characterized by constitutional government change promotes private investment while unconstitutional government change hinders private investment; and (iii) policy uncertainty characterized by variability of contract enforcement rights promotes private investment while variability of government political capacity hinders private investment. Copyright © 2004 John Wiley & Sons, Ltd.
Aggregate agricultural supply response in Ethiopia: a farm‐level analysis
Authors: Abrar Suleiman , Morrissey Oliver , Rayner Tony 
Published: May 2004

AbstractThis study examines the responsiveness of peasant farmers in Ethiopia to price and non‐price factors. Quadratic production and restricted profit functions are estimated using farm‐level survey data from Ethiopia in 1994. The results indicate that farmers respond only modestly to price incentives. The own‐price output supply elasticity is very low and output supply is not responsive to fertilizer prices or the wage rate. Non‐price factors are far more important in affecting production and resource use than price incentives. The results are robust to whether the primal or dual approach is used to estimate elasticities. The results underscore the need to strengthen market incentives through effective policies that will improve farmers' access to fertilizer, land and credit, public investment in roads and irrigation. Copyright © 2004 John Wiley & Sons, Ltd.
Growth, poverty and the IMF
Authors: Bird Graham 
Published: May 2004

AbstractAlthough the IMF presents itself as a monetary institution, it plays an important role in providing support to poor countries via its Poverty Reduction and Growth Facility. It is difficult to imagine more central development issues than poverty and growth. However, while there is a broad consensus surrounding the stabilization issues with which IMF programmes conventionally deal, there is much less agreement about the causes of economic growth and poverty. This carries lessons for the design of the PRGF. While most reviews of it focus on ‘process’, this paper offers a more fundamental analysis of the Fund's involvement in growth and poverty reduction. It suggests that the design of conditionality needs to distinguish between elements according to the degree of scientific consensus. It also suggests that the success of the Fund's attempts to facilitate growth and poverty reduction will be severely constrained unless the necessary external, financial support is provided. Copyright © 2004 John Wiley & Sons, Ltd.
Ghost of the financing gap: an overlooked aspect of the aid debate
Authors: Ranaweera Thilak 
Published: May 2004

AbstractIn the decades‐old intense debate on foreign aid, a great deal has been said about qualitative aspects of aid and aid‐effectiveness (i.e. fungibility, among other things). The latest landmark in the debate was the World Bank publication Assessing Aid: What Works, What Doesn't, and Why, which generated a new wave of controversy about foreign aid and policy conditionality. Much of the recent debate has focused on the qualitative aspects of the aid‐growth relationship and the role of ‘good’ policies. However, little attention had been paid so far to some important quantitative aspects. The present study draws attention to this often overlooked aspect of the aid debate to demonstrate that the level of aid requirements of a country is an equally important and integral part of aid and aid‐effectiveness. Estimation of the magnitude of external assistance requirements of countries used by international financial institutions is compared with an alternative model, the so‐called ‘Balance of Payments Constrained Growth Model’ (based on the Harrod trade multiplier). It is revealed that the latter is not a real alternative as it is an incomplete model. More importantly, it is shown that international financial institutions use these quantitative frameworks in a very flexible and pragmatic way to carry on a meaningful policy dialogue with both donors and recipient countries, which has an important bearing on overall aid and aid‐effectiveness. Copyright © 2004 John Wiley & Sons, Ltd.