bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of Fas (CD95)‐induced apoptotic and necrotic cell death by reactive oxygen species in macrophages
Authors: Medan Djordje , Wang Liying , Toledo David , Lu Bin , Stehlik Christian , Jiang Bing‐Hua , Shi Xianglin , Rojanasakul Yon 
Published: September 2004

AbstractAlthough reactive oxygen species (ROS) have long been suspected to play a key role in Fas (CD95)‐induced cell death, the identity of specific ROS involved in this process and the relationship between apoptotic and necrotic cell death induced by Fas are largely unknown. Using electron spin resonance (ESR) spectroscopy, we showed that activation of Fas receptor by its ligand (FasL) in macrophages resulted in a rapid and transient production of hydrogen peroxide (H2O2) and hydroxyl radicals (·OH). The response was visible as early as 5 min and peaked at approximately 45 min post‐treatment. Morphological analysis of total death response (apoptosis vs. necrosis) showed dose and time dependency with apoptosis significantly increased at 6 h after the treatment, while necrosis remained at a baseline level. Only at a 35‐fold increase in apoptosis did necrosis become significant. Inhibition of apoptosis by a pan‐caspase inhibitor, benzyloxycarbonyl‐Val‐Ala‐Asp‐(OMe) fluoromethyl ketone (zVAD‐fmk), significantly inhibited cell necrosis, indicating the linkage between the two events. Catalase (H2O2 scavenger) and deferoxamine (·OH scavenger) effectively inhibited the total death response as well as the ESR signals, while superoxide dismutase (SOD) (O scavenger) had minimal effects. These results established the role for H2O2 and ·OH as key participants in Fas‐induced cell death and indicated apoptosis as a primary mode of cell death preceding necrosis. Because the Fas death pathway is implicated in various inflammatory and immunologic disorders, utilization of antioxidants and apoptosis inhibitors as potential therapeutic agents may be advantageous. © 2004 Wiley‐Liss, Inc.
Cell type‐specific regulation of the TGF‐β‐responsive α2(I) collagen gene by CpG methylation
Authors: Yamane Kenichi , Suzuki Hiroyuki , Ihn Hironobu , Kato Mitsuyasu , Yoshikawa Hirohide , Tamaki Kunihiko 
Published: September 2004

AbstractThe α2(I) collagen gene shows cell type‐specific expression, however, the mechanism behind this specificity remains to be determined. We demonstrate here that transforming growth factor‐beta (TGF‐β)‐mediated induction of α2(I) collagen gene is regulated by DNA methylation in a cell type‐specific manner. Human α2(I) collagen mRNA and type I collagen protein were expressed in normal human fibroblasts (NHF), and also strongly enhanced by TGF‐β; they were not detected in HaCaT, HeLa, or HepG2 cells (termed “collagen‐induction resistant (CIR) cells”) even following stimulation with TGF‐β. On the other hand, the transcriptional activity of exogenously transfected α2(I) collagen promoter was clearly up‐regulated by TGF‐β in the CIR cells as well as in NHF. In the CIR cells, CpG clusters around the transcription start site of the α2(I) collagen gene were heavily methylated, whereas no methylation was detected in NHF. Moreover, α2(I) collagen gene was reactivated in the CIR cells by 5‐Aza‐2‐deoxycytidine (5‐AdC) treatment to some extent. However, demethylation by 5‐AdC was limited and it was unable to recover the TGF‐β responsiveness. In NHF, the α2(I) collagen gene has a Smad3‐accessible chromatin structure and acetylated histones in the promoter regions. By contrast, in the CIR cells, Smad3 failed to bind to the chromatin and histones were not acetylated in this area. Furthermore, in vitro methylation of the reporter gene containing the α2(I) collagen promoter significantly reduced both basal and TGF‐β‐induced enhancement of the transcriptional activity in NHF. Thus, we propose that α2(I) collagen gene provides the first example of the TGF‐β responsive gene whose cell type‐specificity is regulated by CpG methylation. © 2004 Wiley‐Liss, Inc.
Endotoxin disrupts the leucine‐signaling pathway involving phosphorylation of mTOR, 4E‐BP1, and S6K1 in skeletal muscle
Authors: Lang Charles H. , Frost Robert A. 
Published: September 2004

AbstractEndotoxin (i.e., lipopolysaccharide, LPS) impairs skeletal muscle protein synthesis. Although this impairment is not acutely associated with a decreased plasma concentration of total amino acids, LPS may blunt the anabolic response to amino acids. To examine this hypothesis, rats were injected intraperitoneally with LPS or saline (Sal) and 4 h thereafter were orally administered either leucine (Leu) or Sal. The gastrocnemius was removed 20 min later to assess signaling components important in the translational control of protein synthesis. In the Sal‐Leu group phosphorylation of 4E‐BP1 in muscle was markedly increased, compared to values from time‐matched saline‐treated control rats. This change was associated with a redistribution of eukaryotic initiation factor (eIF) 4E from the inactive eIF4E · 4E‐BP1 complex to the active eIF4E · eIF4G complex. In LPS‐treated rats, the Leu‐induced phosphorylation of 4E‐BP1 and changes in eIF4E distribution were partially or completely abrogated. LPS also antagonized the Leu‐induced increase in phosphorylation of S6K1, ribosomal protein S6 and mTOR. Neither LPS nor leu altered the total amount or phosphorylation of TSC2 in muscle. The ability of LPS to blunt the anabolic effects of Leu could not be attributed to differences in the plasma concentrations of insulin or Leu between groups. Furthermore, the replacement of plasma insulin‐like growth factor (IGF)‐I in LPS‐treated rats to basal levels also did not ameliorate the defect in leucine‐induced phosphorylation of S6K1 or S6, although it did reverse the LPS‐induced decrease in the constitutive phosphorylation of mTOR, S6 and 4E‐BP1. Pretreatment with the glucocorticoid receptor antagonist RU486 was unable to prevent the LPS‐induced leucine resistance. In contrast, to the abovementioned results with leucine, LPS did not prevent the ability of pharmacological levels of IGF‐I to phosphorylate 4E‐BP1, S6K1, mTOR or alter the availability of eIF4E. Hence, LPS working via a glucocorticoid‐independent mechanism produces a leucine resistance in skeletal muscle that might be expected to impair the ability of this amino acid to stimulate translation intiation and protein synthesis. © 2004 Wiley‐Liss, Inc.
Phospholipase A2 activating protein (PLAA) is required for 1α,25(OH)2D3 signaling in growth plate chondrocytes
Authors: Schwartz Z. , Graham E.J. , Wang L. , Lossdörfer S. , Gay I. , Johnson‐Pais T.L. , Carnes D.L. , Sylvia V.L. , Boyan B.D. 
Published: September 2004

AbstractPhospholipase A2 (PLA2) is pivotal in the rapid membrane‐mediated actions of 1,25‐dihydroxyvitamin D3 [1α,25(OH)2D3]. Microarray analysis indicated that PLA2 activating protein (PLAA) mRNA is upregulated 6‐fold before rat growth plate cells exhibit 1α,25(OH)2D3‐dependent protein kinase C (PKC) increases, suggesting that it plays an important role in 1α,25(OH)2D3's mechanism of action. PLAA mRNA was confirmed in 1α,25(OH)2D3‐responsive growth zone (prehypertrophic and upper hypertrophic cell zones) chondrocytes by RT‐PCR and Northern blot in vitro and by in situ hybridization in vivo. PLAA protein was shown by Western blot and immunohistochemistry. PLAAs role in 1α,25(OH)2D3 signaling was evaluated in growth zone cell cultures using PLAA peptide. Arachidonic acid release was increased as was PLA2‐specific activity in plasma membranes and matrix vesicles. PKCα, but not PKCβ, PKCε, or PKCζ, was increased. PLAAs effect was comparable to that of 1α,25(OH)2D3 and was additive with 1α,25(OH)2D3. PLA2 inhibitors quinacrine and AACOCF3, and cyclooxygenase inhibitor indomethacin blocked the effect of PLAA peptide on PKC, indicating arachidonic acid and its metabolites were involved. This was confirmed using exogenous arachidonic acid. Prostaglandin acted via EP1 based on inhibition by SC19220 and not via EP2 since AH6809 had no effect. Like 1α,25(OH)2D3, PLAA peptide also increased activity of phospholipase C‐specific activity via beta‐1 and beta‐3 isoforms, but not delta‐1 or gamma‐1; the effect of PLAA was via lysophospholipid but not via arachidonic acid. PLAA peptide decreased [3H]‐thymidine incorporation to 50% of the decrease caused by 1α,25(OH)2D3. In contrast, PLAA peptide increased alkaline phosphatase‐specific activity and proteoglycan production in a manner similar to 1α,25(OH)2D3. This indicates that PLAA is a specific activator of PLA2 in growth plate chondrocytes, and suggests that it mediates the membrane effect of 1α,25(OH)2D3, thereby modulating physiological response. © 2004 Wiley‐Liss, Inc.
Expression of PDGF and their receptors in human retinal pigment epithelial cells and fibroblasts: Regulation by TGF‐β
Authors: Nagineni Chandrasekharam N. , Kutty Veena , Detrick Barbara , Hooks John J. 
Published: September 2004

AbstractPlatelet derived growth factors (PDGF) are known to be associated with vitreoretinal disorders such as proliferative vitreoretinopathy (PVR). We have studied the expression of PDGF and their receptors in human retinal pigment epithelial cells (HRPE) and choroid fibroblasts (HCHF), and the regulation of PDGF and its receptors by various cytokines and growth factors. RT‐PCR analyses showed enhanced expression of PDGF‐A and PDGF‐B mRNA in HRPE treated with TGF‐β, but not with other cytokines. A minimal increase was observed in PDGF‐A mRNA in TGF‐β treated HCHF cells. PDGF‐Rα mRNA, which was expressed prominently in HCHF and at very low levels in HRPE, was not affected by any of the agents. PDGF‐Rβ was not detectable in either HRPE or HCHF. HRPE secreted PDGF‐AA and AB constitutively, and this secretion was significantly enhanced by TGF‐β. In contrast, HCHF cultures did not secrete detectable levels of any of the three isoforms of PDGF (AA, AB, BB). All three human recombinant PDGF isoforms enhanced HCHF cell proliferation significantly, while only a minimal increase was observed in HRPE. PDGF isoforms also induced HCHF cell elongation and promoted migration of HCHF in an in vitro wound assay. The results presented in this study demonstrate that TGF‐β activated RPE cells produce PDGF that may act on fibroblasts and other mesenchyme derived cells which express PDGF receptors. These studies indicate that the promotion of the proliferation and migration of mesenchymal cells by RPE cell derived PDGF may facilitate the formation of fibrovascular tissues associated with PVR. © 2004 Wiley‐Liss, Inc.
A thermal study on the use of immobilized penicillin G acylase in the formation of 7‐amino‐3‐deacetoxy cephalosporanic acid from cephalosporin G
Authors: Pan Jian‐Liang , Syu Mei‐Jywan 
Published: September 2004

AbstractPenicillin G acylase (PGA) is an important enzyme for the industrial production of 7‐amino‐3‐deacetoxy cephalosporanic acid (7‐ADCA) from cephalosporin G (Ceph‐G), and 6‐aminopenicillanic acid (6‐APA) from penicillin G (Pen‐G). These products are used for the manufacture of semi‐synthetic cephalosporins and penicillins. In this study, immobilized PGA was utilized to catalyze the conversion of Ceph‐G to 7‐ADCA. The optimal conditions were found to be an operating temperature of 45 °C, 0.2 M phosphate buffer, a substrate concentration of 30 mg cm−3 and a catalyst particle concentration of 0.01 g cm−3 (specific activity of 623.2 U g−1). Up to 45 °C the reaction was characterized by an activation energy of 38.66 kJ mol−1. Beyond 57.5 °C there was a sharp decline of activity, characterized by a deactivation energy of 235.88 kJ mol−1. Copyright © 2004 Society of Chemical Industry
Kinetics of esterification of palmitic acid with isopropanol using p‐toluene sulfonic acid and zinc ethanoate supported over silica gel as catalysts
Authors: Aafaqi Roomana , Mohamed Abdul Rahman , Bhatia Subhash 
Published: September 2004

AbstractKinetic data on the esterification of palmitic acid with isopropanol were obtained using homogeneous (para‐toluene sulfonic acid, p‐TSA) and heterogeneous (zinc ethanoate coated on silica gel, ZnA/SG) catalysts in a batch reactor. The ZnA/SG catalyst was prepared using a sol–gel technique. The esterification reaction was studied at different reaction temperatures (373–443 K), initial reactants molar ratio (1–5), catalyst loading (1–5 gcat dm−3) and water concentration in feed (0–15 vol%). A power law rate equation was used for homogeneous kinetics analysis. The Langmuir Hinshelwood Hougen Watson (LHHW) model was used for heterogeneous kinetics. The kinetic parameters of both models were obtained using Polymath software. The reaction parameters were used to obtain simulated values of conversion for both catalytic systems. The simulated values were compared with the experimental values and were in good agreement. Copyright © 2004 Society of Chemical Industry
The effect of raw glycerol concentration on the production of 1,3‐propanediol by Clostridium butyricum
Authors: Papanikolaou Seraphim , Fick Michel , Aggelis George 
Published: September 2004

AbstractRaw glycerol, the main by‐product of the bio‐diesel production process, was converted to 1,3‐propanediol by Clostridium butyricum F2b. In batch cultures, 47.1 g dm−3 of 1,3‐propanediol were produced. Continuous cultures were conducted at a constant dilution rate (= 0.04 h−1) and various inlet glycerol concentrations with 1,3‐propanediol produced at levels up to 44.0 g dm−3. At increasing glycerol concentrations in the inlet medium, biomass yield decreased. This decrease was attributed to the microbial metabolism being directed towards the biosynthesis of organic acids (and hence carbon losses as CO2) instead of biochemical anabolic reactions. An autonomous analytical model was developed, and quantified the effect of inlet glycerol concentration on the production of biomass and metabolites. Indeed, high inlet substrate concentrations positively affected the biosynthesis, principally of butyric acid and to a lesser extent that of acetic acid. In contrast, at increased glycerol concentrations, the relative increase of 1,3‐propanediol production per unit of substrate consumed was lower as compared with that of acetic and, mainly, butyric acid. This could be explained by the fact that the butyric acid pathway represents an alternative and competitive one to that of 1,3‐propanediol for re‐generation of NADH2 equivalents in the microbial cell. Copyright © 2004 Society of Chemical Industry
Treatment of textile dye wastewater by using an electrochemical bipolar disc stack reactor
Authors: Muthukumar Karuppan , Sundaram P Shunmuga , Anantharaman N , Basha C Ahmed 
Published: September 2004

AbstractTextile dye house wastewater from a reactive dye processing unit was treated by using an electrochemical oxidation technique. The experiments were carried out in an electrochemical bipolar disc reactor using RuO2 coated on titanium as anode and titanium as cathode. The sodium chloride present in the effluent was used as supporting electrolyte. Operating parameters such as current density, reservoir hold‐up and electrolysis time were studied for maximum Chemical Oxygen Demand (COD) reduction and other relevant parameters such as current efficiency and power consumption per kg of COD removal were calculated. The higher flow rate and lower reservoir hold‐up resulted in improved COD removal. The applied current density was also found to significantly influence the reduction of COD. A suitable mathematical model is also proposed to illustrate the relationship between the basic parameters. Pseudo mass transfer coefficients were also evaluated for different experimental conditions. Copyright © 2004 Society of Chemical Industry
Monitoring of cell growth using the focused beam reflectance method
Authors: Pearson Alan P , Glennon Brian , Kieran Patricia M 
Published: September 2004

AbstractIn this paper the use of a focused beam reflectance measurement (FBRM) particle characterisation probe was investigated as a tool for monitoring the growth of the filamentous bacteria Streptomyces natalensis. The optimum operating parameters of the probe were identified, and it was found that the sample agitation rate had the largest effect on the mean value of a number of statistics of the chord length distribution (CLD) measured by the FBRM probe. A series of fractions of the particle size distribution was generated by sieving. It was found that the mean chord length measured by the probe responded to changes in the size distribution examined, increasing from 57.2 µm to 69.9 µm with an increase in the upper particle size from 180 µm to 300 µm. It was also found that the average total counts measured by the probe also increased with increasing sample concentration. This relationship was further investigated and it was found that in the normal range of biomass levels experienced in a fermentation (up to 4.0 g dm−3) there was an apparently linear relationship between counts and concentration. However, as concentration was increased further the relationship became increasingly non‐linear. Copyright © 2004 Society of Chemical Industry
Efficient purification and morphology characterization of paclitaxel from cell cultures of Taxus chinensis
Authors: Pyo Sang‐Hyun , Kim Moon‐Suk , Cho Jin‐Suk , Song Bong‐Kyu , Han Byung‐Hee , Choi Ho‐Joon 
Published: September 2004

AbstractPaclitaxel was purified from cell cultures of Taxus chinensis by a combination of extraction, low‐pressure chromatography, precipitation and HPLC. A crude extract (purity 6.9%) was obtained by methanol extraction of plant cell cultures, followed by liquid–liquid extraction using dichloromethane. The extract was purified to greater than 32% with a 97% step yield by low‐pressure chromatography. After acetone/pentane precipitation, the resulting purity and step yield were 75.8% and 97.4%, respectively. High performance liquid chromatography steps, which were composed of an HPLC step with column‐packed ODS and an HPLC step with column‐packed silica, were applied to give over 99.5% purity with high yield. Amorphous paclitaxel with a fine particle size, which has a solubility advantage compared with the stable crystalline form, was obtained by dissolving in dichloromethane, followed by spray‐drying. Copyright © 2004 Society of Chemical Industry
Investigating the use of cooling surfaces in solid‐state fermentation tray bioreactors: modelling and experimentation
Authors: Khanahmadi Morteza , Roostaazad Reza , Safekordi Aliakbar , Bozorgmehri Ramin , Mitchell David A 
Published: September 2004

AbstractThe effect of wall cooling in tray‐type solid‐state fermenters was investigated by cultivation of Aspergillus niger ATCC 10 864 on wheat bran. Temperature, moisture, pH and glucoamylase activity in the bed were monitored. Application of the heat exchanger plate reduced the overall water loss but increased the heterogeneity of moisture distribution in the bed. Moisture content increased markedly close to the heat transfer plate while the upper regions of the bed dried out. The thermal conductivity of the bed was measured to be 0.19 W m−1 K−1. At these conditions and depending on the air flow rate, 58–82% of the metabolic heat was removed via conduction towards the plate. A mathematical model was developed to describe the behaviour of the system. Model predictions were in good agreement with the experimental results. Diffusion coefficients of water vapour and oxygen in the bed were estimated to be around 1.3 × 10−5 m2 s−1 and 1 × 10−5 m2 s−1 respectively. Based on these values the mathematical model describes the way oxygen and water vapour diffusion influences biomass growth and moisture distribution in the bed. Copyright © 2004 Society of Chemical Industry
An anion exchange resin from soybean hulls
Authors: Marshall Wayne E , Wartelle Lynda H 
Published: September 2004

AbstractAgricultural by‐products are generally poor adsorbents of anions in solution. Therefore, modification of the by‐product could enhance its anion exchange capabilities. The objective of this study was to increase the anion exchange properties of the agricultural by‐product, soybean hulls, by chemical modification. Soybean hulls were quaternized with the quaternizing agent, N‐(3‐chloro‐2‐hydroxypropyl) trimethylammonium chloride, in the presence of a strongly alkaline environment. This modification increased the amount of positive charge on the hulls as evidenced by increased nitrogen content and increased uptake of anions compared with the unmodified hulls. A method to optimize the anion exchange properties of the hulls was developed. Ion exchange properties of the hulls toward anions of environmental significance, namely arsenate (As), chromate (Cr), dichromate (Cr2), phosphate (P) and selenate (Se) were determined. The modified hulls were also compared with commercial cellulose‐based and synthetic anion exchange resins in their ability to remove these anions from solution. The experimental and commercial resins were also compared for their ability to remove a mixture of arsenate, chromate, dichromate and selenate from laboratory prepared solutions to levels below the maximum contaminant levels for these anions in drinking water as specified by the US Environmental Protection Agency (US EPA). Our results demonstrate that the soy hull resin is more efficient in anion removal than the commercial cellulose‐based resin but not as effective as the commercial synthetic resin. Published in 2003 for SCI by John Wiley & Sons, Ltd.
Characteristics of photocatalytic oxidation of gaseous 2‐propanol using thin‐film TiO2 photocatalyst
Authors: Chang Chiu‐Ping , Chen Jong‐Nan , Lu Ming‐Chun 
Published: September 2004

AbstractThis work presents a photocatalysis‐based method to treat and purify air because of its broad applicability to common, oxidizable, air contaminants. The effect of oxygen content, temperature, water vapor, and 2‐propanol concentration on the TiO2 surface was investigated. The rate of 2‐propanol decomposition increased with increasing the oxygen content, but was reduced at temperatures higher than 100°C. When water vapor concentration was in the range of 10–355 mmol m−3, the rate of 2‐propanol decomposition was proportional to the water content. However, an opposite result was observed at a higher concentration of water vapor. 2‐Propanol was photooxidized to acetone, and eventually to carbon dioxide and water. The kinetic model of 2‐propanol photooxidation was successfully developed by the competitive Langmuir–Hinshelwood rate form, incorporating the inhibition effect coming from the formation of acetone. Copyright © 2004 Society of Chemical Industry
Solvent extraction of zirconium(IV) from acidic chloride solutions using the thiosubstituted organophosphorus acids Cyanex 301 and 302
Authors: Ramachandra Reddy B , Rajesh Kumar J , Varada Reddy A 
Published: September 2004

AbstractSolvent extraction of zirconium(IV) from acidic chloride solutions has been carried out with the thiosubstituted organophosphorus acids Cyanex 301 and Cyanex 302. The extraction follows an ion exchange mechanism: MO2+(aq) + 2 HA(org) ↔ MOA2(org) + 2 H+(aq), where, M = Zr(IV); HA = Cyanex 301 or Cyanex 302. The plots of log D (distribution ratio) vs log [HA], are linear with slopes of 2, indicating the association of two moles of extractant with the extracted metal species. The plots of log D vs log [H+] gave straight lines with a negative slope of 1.7 for Cyanex 301 and 1.8 for Cyanex 302, indicating the exchange of two moles of hydrogen ions for every mole of Zr(IV). Addition of sodium salts enhanced the extraction of metal. The stripping behavior of metal from the loaded organic (LO) with HCl and H2SO4 was studied. Increase of temperature during the extraction and the stripping stage increases the metal transfer, showing the process is exothermic. Mixed extractants, the extraction behavior of associated elements such as Hf(IV), Ti(IV), Al(III), Fe(III) and the IR spectra of the metal complexes were studied. Copyright © 2004 Society of Chemical Industry