bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemically Initiated Catalytic Oxidation of 5‐Thio‐2‐Nitrobenzoic Acid (TNBA) in the Presence of Thiols at a Boron Doped Diamond Electrode: Implications for Total Thiol Detection
Authors: Nekrassova Olga , Lawrence Nathan S. , Compton Richard G. 
Published: November 2003

AbstractThe electrochemical response of 5,5‐dithiobis(2‐nitrobenzoic acid) (DTNB) to increasing additions of thiol species has been examined at a boron doped diamond electrode. A reaction has been shown to occur with a range of biologically relevant thiols and proceeds via a CECC' process. A total thiol detection methodology has been developed showing that the sensitivities of the standard addition plots are independent of the individual thiol species added to the solution. The analytical utility of the reaction process has been assessed using chronoamperometry with the corresponding data producing detection limits of 5.7 μM, 4.4 μM and 5.8 μM for the detection of cysteine, homocysteine and glutathione respectively.
Hydrolytic cleavage of purine ribonucleosides in Aspergillus phoenicis
Authors: Abdel‐Fatah Osama M. , Elsayed Maysa A. , Elshafei Ali M. 
Published: November 2003

AbstractCell‐free extracts of nitrate‐grown Aspergillus phoenicis could catalyze the hydrolytic cleavage of the N‐glycosidic bond of inosine, guanosine and adenosine to the corresponding base and ribose by the nucleoside hydrolase. No evidence was obtained concerning the hydrolytic degradation of N‐glycosidic bond of pyrimidine ribonucleosides namely cytidine and uridine by the same extracts. Optimum pH and temperature for adenosine, guanosine and inosine hydrolysis were the same at pH 3.5 and 55 °C, respectively. Citrate buffer showed the highest hydrolase activity when compared to the analogous activity obtained with the other buffers used. The rate of hydrolysis of the three nucleosides was in the order inosine > guanosine > adenosine. Incubation of extracts at 55 °C for 15 minutes caused about 85%, 75% and 62% loss of activity with adenosine, guanosine and inosine respectively. Dialyzing the extract caused a decrease in enzyme activity. Addition of inorganic arsenate to the reaction mixture (containing adenosine, guanosine or inosine) did not affect the amount of ribose liberated. Addition of EDTA at a concentration of 5 × 10−3 M caused an inhibition of about 50%, however a complete inhibition for enzyme activity was obtained at 10−2 M EDTA. MgSO4, CoSO4 and ZnSO4 at a final concentration of 5 × 10−3 M showed activation of ribonucleoside hydrolase.
Biotransformation of N‐(2‐alkylamino‐4‐phenylimidazol‐1‐yl)‐acetamides and kinetic studies by using cells and laccase from Trametes versicolor
Authors: Mikolasch Annett , Schauer Frieder 
Published: November 2003

AbstractThe product pattern of biotransformation of different N‐(2‐alkylamino‐4‐phenylimidazol‐1‐yl)‐acetamides were compared. N‐(2‐alkylamino‐4‐phenylimidazol‐1‐yl)‐acetamides were transformed by Trametes versicolor into two types of aromatic products identified by chemical structure analysis: 1. Novel heteroaromatic compounds, such as: 2‐(alkylamino)‐4‐phenylimidazoles, N‐(2‐alkylamino‐5‐formyl‐4‐phenylimidazol‐1‐yl)‐acetamides, N‐(2‐alkylimino‐3‐hydroxy‐4‐phenyl‐2,3‐dihydroimidazol‐1‐yl)‐acetamides and N‐(2‐alkylimino‐5‐oxo‐4‐phenyl‐2,5‐dihydroimidazol‐1‐yl)‐acetamides, 2. Novel compounds arising from coupling of two molecules of the substrate. These aromatic compounds were produced from the beginning of incubation by cultures of T. versicolor.In addition to these two types of biotransformation products, monoaromatics such as oxophenyl acetic acid, benzoic acid, and benzyl alcohol were formed as degradation products resulting from an extended incubation of the substrates and from the degradation of the first two types of transformation products.Crude preparations of laccase from T. versicolor catalysed only the formation of novel heteroaromatic compounds, though they do so with higher yields and in shorter time than cultures of T. versicolor.
Using application service providers: yes or no?
Authors: Focacci Luisa , Dologite Dorothy G. , Mockler Robert J. , Gartenfeld Marc E. 
Published: November 2003

Abstract

A firm should do whatever is necessary to survive and prosper and therefore its strategy should depend on the particular situation and the critical importance of the key core activity involved.
One specific question might be whether or not to go outside its boundaries and use an application service provider (ASP) in strategically significant core activity areas where knowledge and information networks are critical to its success.
This paper develops some contingency guidelines for making this specific decision that can be adapted to similar decisions in other core activity business process areas.

Copyright © 2003 John Wiley & Sons, Ltd.
Towards global analysis of mosquito chorion proteins through sequential extraction, two‐dimensional electrophoresis and mass spectrometry
Authors: Yao Ruiliang , Li Jianyong 
Published: November 2003

AbstractThis study describes the separation and identification of chorion proteins through two‐dimensional electrophoresis (2‐DE) and matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry (MALDI‐TOF MS) techniques. Due to their high hydrophobicity, chorion proteins are difficult to be solubilized and absorbed into the immobilized pH gradient strip for isoelectric focusing. By optimizing the applied conditions for chorion protein extraction and sample application, we were able to solubilize the majority of the chorion proteins and resolve them by 2‐DE. Under optimized conditions, there are more than 700 protein spots resolved by 2‐D analysis. Trypsin digestions of individual protein spots, MALDI‐TOF MS analysis of their digested peptides, and subsequent BLAST search of peptide masses resulted in the tentative identification of 38 protein spots. Our data show that sequential extraction of the isolated chorion, 2‐DE of the solubilized chorion proteins, in‐gel digestion of the resolved protein and MALDI‐TOF MS analysis of the protein digests is an effective overall strategy towards determination of chorion proteins in mosquitoes. The merits of the method described for the determination of mosquito chorion proteins and its feasibility for the separation and identification of membrane proteins and chorion or eggshell proteins from other insect species are discussed.
Parvovirus B19 and the pathogenesis of anaemia
Authors: Chisaka Hiroshi , Morita Eiji , Yaegashi Nobuo , Sugamura Kazuo 
Published: November 2003

AbstractHuman parvovirus B19 (B19) infection causes human bone marrow failure, by affecting erythroid‐lineage cells which are well‐known target cells for B19. The anaemia induced by B19 infection is of minor clinical significance in healthy children and adults, however, it becomes critical in those afflicted with haemolytic diseases. This condition is called transient aplastic crisis, and the pathogenesis is explained by the short life‐span of red blood cells. Similarly, fetuses are thought to be severely affected by B19‐intrauterine infection in the first and second trimester, as the half‐life of red blood cells is apparently shorter than RBC at the bone marrow haematopoietic stage. On the other hand, B19 is also the causative agent of persistent anaemia in immunocompromised patients, transplant recipients and infants. The deficiencies of appropriate immune responses to B19 impair viral elimination in vivo, which results in enlargement of B19‐infected erythroid‐lineage cells. The B19‐associated damage of erythroid lineage cells is due to cytotoxicity mediated by viral proteins. B19‐infected erythroid‐lineage cells show apoptotic features, which are thought to be induced by the non‐structural protein, NS1, of B19. In addition, B19 infection induces cell cycle arrests at the G1 and G2 phases. The G1 arrest is induced by NS1 expression prior to apoptosis induction in B19‐infected cells, while the G2 arrest is induced not only by infectious B19 but also by UV‐inactivated B19, which lacks the ability to express NS1. In this review, we address the clinical manifestations and molecular mechanisms for B19‐induced anaemia in humans and a mouse model, and of B19‐induced cell cycle arrests in erythroid cells. Copyright © 2003 John Wiley & Sons, Ltd.
Towards cellular receptors for prions
Authors: Lee Kil Sun , Linden Rafael , Prado Marco Antônio M. , Brentani Ricardo R. , Martins Vilma R. 
Published: November 2003

AbstractTransmissible spongiform encephalopathies (TSE) are attributed to the conversion of the cellular prion protein (PrPc) into an abnormal isoform (PrPsc). This can be caused by the invasion of living organisms by infectious particles, or be inherited due to mutations on the PrPc gene. One of the most intriguing problems of prion biology is the inability to generate the infectious agent in vitro. This argues strongly that other cellular proteins besides those added in test tubes or found in cellular preparations are necessary for infection. Despite recent progress in the understanding of prion pathology, the subcellular compartments in which the interaction and conversion of PrPc into PrPsc take place are still controversial. PrPc interacts with various macromolecules at the cell membrane, in endocytic compartments and in the secretory pathway, all of which may play specific roles in the internalisation of PrPsc and conversion of PrPc. A specific interacting protein required for the propagation of prions was originally proposed as a prion receptor, and later referred to as a ligand, a cofactor, protein X, or a partner. However, current studies indicate that PrPc associates with multi‐molecular complexes, which mediate a variety of functions in distinct cellular compartments. It is proposed that a deeper understanding of the mechanics of such interactions, coupled to a better knowledge of the corresponding signalling pathways and ensuing cellular responses, will have a major impact on the prevention and treatment of TSE. Copyright © 2003 John Wiley & Sons, Ltd.
Oscillation theorems for discrete nonlinear delay wave equations
Authors: Kubiaczyk I. , Saker S.H. 
Published: November 2003

AbstractIn this paper we shall discuss the oscillatory behavior of the solutions of nonlinear discrete delay wave equation. We will reduce the oscillation of the boundary value problem to the oscillation of the ordinary difference equation with damped term. By using the Riccati transformation techniques we will establish some new oscillation criteria for all solutions in the domain under consideration.
Spreading melts with basal solidification
Authors: Bunk M.A. , King J.R. 
Published: November 2003

AbstractSpreading of melts under the influence of solidification has a wide range of applications in engineering and nature. The isothermal spreading process of a viscous melt under the influence of gravity has been well studied in the literature. Features of many practical spreading flows, however, cannot be described with an isothermal model, non‐isothermal effects often being non‐negligible. Due to the range of properties of the melt and possible thermal boundary conditions, many different problems suggest themselves; this paper concerns the spreading of melts on a horizontal substrate under the influence of basal solidification. Using lubrication theory for spreading flows in the viscous/gravitational regime the influence of solidification on the spreading flow is considered for melts with a large release of latent heat. We consider two‐dimensional melts with cross‐sectional area be proportional to tα. The results show different spreading regimes, depending on the parameter α. We get complete solidification for α = 0, retreating contact lines for 0 < α < 1/2, stagnating contact lines for α = 1/2, and advancing contact lines for α > 1/2. The asymptotic behaviour for short and large times is discussed, clarifying the various regimes.
Flight of male Cadra cautella along plumes of air and pheromone superimposed on backgrounds of pheromone
Authors: Schofield Steven W. , Justus Kristine A. , Mafra‐Neto Agenor , Cardé Ring T. 
Published: November 2003

AbstractMale Cadra cautella were presented with five heterogeneous pheromone clouds (created from source doses of 0, 0.01, 1, 100, and 10 000 ng) with and without superimposed plumes of either clean air or sex pheromone in a wind tunnel. Moths provided with the lowest doses of background clouds without a superimposed plume did not fly upwind. Moths provided with higher doses of background clouds, with or without superimposed air plumes, increased their track, course, and drift angles (i.e., their zigzags headed more towards crosswind) with increased dose, but slowed their velocity. No differences in flight track parameters were observed for moths provided with a superimposed pheromone plume, regardless of the background cloud dose. Moreover, moths were able to locate the source of superimposed air plumes in the highest background dose, and of superimposed pheromone plumes in any background dose. The significance of these results is discussed in the context of mating disruption.
Microbial population dynamics related to temporal variations in nitrification in three arable fields
Authors: Wheatley R. E. , Caul S. , Crabb D. , Daniell T. J. , Griffiths B. S. , Ritz K. 
Published: November 2003

SummaryIt seems possible that soil potential nitrification rates (PNRs) are determined by the size and structure of both the eubacterial and nitrifier populations. We have examined this possibility by comparing the structure of the eubacterial community with the subcomponents and dynamics of the ammonium‐oxidizer population, within and between three arable fields. PNRs were significantly different between the three fields and also showed significantly different temporal patterns within each field. The use of eubacterial primers in polymerase chain reaction–denaturing gel gradient electrophoresis (PCR–DGGE) analyses indicated that the bacterial community structure in each field was significantly different from that in the others, and that the bacterial components of these communities changed with time through the season. In contrast, PCR–DGGE analyses specific to ammonium oxidizers suggested that the populations in all three fields were similar in types and did not vary with time. Competitive PCR suggested that there were large and biologically significant differences in the size of the nitrifier population between the three fields, but that within each individual field populations did not change over time. Sequencing identified the ammonium oxidizers in the Nitrosospira spp. cluster. There was also no relation between the size of the nitrifier populations and PNR. Functional expression, as PNR, apparently responded to changes in eubacterial community structure.
Pollution induced community tolerance (PICT) and analysis of 16S rRNA genes to evaluate the long‐term effects of herbicides on methanotrophic communities in soil
Authors: Seghers D. , Bulcke R. , Reheul D. , Siciliano S. D. , Top E. M. , Verstraete W. 
Published: November 2003

SummaryThere is an increasing interest in agricultural systems in which the use of herbicides is forbidden. Therefore, soils treated with herbicides atrazine and metolachlor for the last 20 years were compared with soil samples from the same field that had never been treated (control soil). We determined the pollution induced community tolerance (PICT) by evaluating the methane oxidation capacity of soil samples after adding increasing amounts of a methane oxidation inhibitor, 2,4‐dichlorophenoxyacetic acid (2,4‐D). Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes assessed whether the soil methanotrophic community differed between the two treatments. Addition of 60 µg 2,4‐D per g soil clearly inhibited methane oxidation in both soils but increased the time needed to oxidize 5% methane in the headspace by 250% for the control soil compared with 175% for the herbicide‐treated soil. This indicates that the soil with a long‐term herbicide history had a greater tolerance to the methane oxidation inhibitor than did the control soil. The DGGE of 16S rRNA genes amplified directly from soil community DNA could also distinguish the two treatments. The banding patterns of the Type I methanotrophs contained fewer bands in the herbicide‐treated soil. It seems that both the PICT approach and DGGE analysis are effective assays to distinguish a long‐term herbicide‐treated soil from an untreated soil.
Suppressive effect of tetraprenylacetone on gastric atrophy induced by short‐term administration of N‐methyl‐N′‐nitro‐ N‐nitrosoguanidine in rats
Authors: Miwa H. , Nagahara A. , Wada R. , Hirai S. , Endo K. , Watanabe S. , Sato N. 
Published: November 2003

Background:Several studies have been reported on the effects of various therapeutic agents in enhancing or suppressing the carcinogenic activity of N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG). However, it is still unknown whether a mucosal protective agent could suppress its carcinogenic activity.Methods:Twenty‐five Wistar male rats were divided into four groups: group 1, MNNG alone; group 2, MNNG + tetraprenylacetone; group 3, control; group 4, tetraprenylacetone alone. MNNG 100 mg/mL was freely given to groups 1 and 2, and tetraprenylacetone (200 mg/kg intraperitoneal) was additionally administered every other day to the rats in groups 2 and 4. The animals were sacrificed at 10 weeks and the gastric mucosa examined.Results:Atrophic changes were observed in the antrum after 8 weeks of oral administration of MNNG. Furthermore, using immunohistological analysis with 5‐bromo‐2′‐deoxyuridine (BrdU), the proliferative zone was found to be enlarged and shifted upward, although the BrdU labelling index of the proliferative zone was unaltered. Intraperitoneal administration of tetraprenylacetone every other day suppressed the MNNG‐induced atrophic change and the alterations proliferative markers. Tetraprenylacetone alone did not have an effect either on morphological or proliferative markers.Conclusion:These observations suggest that gastric mucosal defensive factors may play critical roles in suppressing atrophic change inducing carcinogenesis by an exogenic carcinogen.
Furazolidone, amoxycillin, bismuth triple therapy for Helicobacter pylori infection
Authors: Segura A. M. , Gutiérrez O. , Otero W. , Angel A. , Genta R. M. , Graham D. Y. 
Published: November 2003

Background:Metronidazole‐resistant Helicobacter pylori are generally the rule in developing countries such as Colombia. Developing countries need an effective, simple and inexpensive non‐metronidazole therapy for H. pylori infection.Aim:To evaluate the combination of bismuth, furazolidone and amoxycillin for the treatment of H. pylori infection in Colombia.Methods:Thirty patients with histologically documented H. pylori infection received the combination of bismuth subcitrate 240 mg b.d., furazolidone 100 mg q.d.s. and amoxycillin 500 mg q.d.s. for 14 days. Four or more weeks after ending therapy patients were re‐endoscoped and gastric biopsies were obtained and examined using the Genta stain. Each slide was scored for presence, absence and density of H. pylori, active and chronic inflammation, intestinal metaplasia, erosions and atrophy. Cure was defined as the absence of H. pylori.Results:All patients completed the course of therapy. Twenty‐five patients were cured (86%, 95% CI: 65–94%). Mild, well‐tolerated side‐effects were reported by six patients (20%).Conclusions:This combination of bismuth, furazolidone and amoxycillin fulfills the criteria for successful H. pylori therapy and appears particularly well suited for developing countries since it is simple, inexpensive and effective. Furazolidone‐containing therapies may become especially useful in the face of a world‐wide increase in H. pylori resistance to metronidazole and macrolides.
NSAIDs upregulate β2‐integrin expression on human neutrophils through a calcium‐dependent pathway
Authors: Fiorucci S. , Santucci L. , Gerli R. , Brunori P. M. , Federici B. , Ugolini B. , Fabbri C. , Morelli A. 
Published: November 2003

Background:Margination of circulating neutrophils (PMN) into the gastric microcirculation is an early and critical event in the pathogenesis of non‐steroidal antinflammatory drug (NSAID)‐induced gastropathy. This effect is mediated through the upregulation of β2 integrins on the PMN surface.Aims:To investigate whether indomethacin modulates: (1) Mac‐1 expression; (2) Ca2+ mobilization ([Ca2+]i), protein kinase C and nitric oxide accumulation; and (3) mitogen‐associated protein kinase phosphorylation in human PMN.Methods:Human PMN were isolated by centrifugation through a double Ficoll gradient. [Ca2+]i was measured in PMN loaded with fura‐2 and Mac‐1 expression by flow cytometry.Results:Indomethacin caused a concentration‐ and time‐dependent upregulation of CD11b and CD18 expression and PMN adhesion to endothelial cells. Maximal upregulation of Mac‐1 expression (40–50%) occurred after a 30‐min incubation with 0.1 mM indomethacin. The effect was prevented by removing the Ca2+. Ionomycin and thapsigargin caused a 7–10‐fold increase in [Ca2+]i and a 2–4‐fold increase in Mac‐1 expression. Indomethacin induced a concentration‐dependent phosphorylation of a 41‐kDa mitogen‐associated protein kinase. Tyrosine kinase inhibitors prevented the effect of indomethacin on Mac‐1 expression and Ca2+ mobilization. Indomethacin and ionomycin increased superoxide generation, myeloperoxidase secretion and PMN adherence to endothelial cells and stimulated nitric oxide production. Indomethacin‐induced Mac‐1 upregulation was prevented by a nitric oxide synthase inhibitor.Conclusions:Indomethacin‐induced upregulation of Mac‐1 is mediated by changes in [Ca2+]i and nitric oxide. Phosphorylation of the 41‐kDa mitogen‐associated protein isoform is a previously unreported target of NSAID action. These effects might help to explain the ability of indomethacin to cause gastric neutrophil margination.
Haemodynamic effects of octreotide in portal hypertensive rats receiving propranolol
Authors: MOREAU R. , CAILMAIL S. , GADANO A. , VALLA D. , LEBREC D. 
Published: November 2003

Background: The aim of this study was to investigate short‐term effects of propranolol (a non‐selective β‐adrenergic antagonist), octreotide (a long‐acting somatostatin analogue), or a combination of these substances on splanchnic and systemic haemodynamics and arterial blood gases in rats with portal vein stenosis. Methods: Splanchnic and systemic haemodynamics were measured using the radioactive microspheres method. Eight rats first received an i.v. infusion of isotonic saline (10 μL/min for 15 min) and then an i.v. infusion of octreotide (8 μg.h/kg for 15 min). Eight other rats first received a bolus i.v. injection of propranolol (2 mg) and an i.v. infusion of octreotide 15 min later. Results: Propranolol or octreotide alone significantly decreased portal pressure (both by 23%), portal tributary blood flow (35 and 10%, respectively) and cardiac index (36 and 26%, respectively). Octreotide administration in rats pretreated with propranolol significantly decreased cardiac index but did not change portal and arterial pressures or portal tributary blood flow. Propranolol significantly increased arterial oxygen tension. Octreotide alone or combined with propranolol significantly decreased oxyhaemoglobin saturation and pH and increased carbon dioxide tension. Conclusions: In rats with portal vein stenosis, the somatostatin analogue, octreotide, accentuates the short‐term decrease in cardiac index due to propranolol. In addition, octreotide altered arterial blood gases and acid‐base status. In contrast, octreotide does not further decrease portal pressure in animals receiving propranolol.