bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catchment urbanisation and increased benthic algal biomass in streams: linking mechanisms to management
Authors: Taylor Sally L. , Roberts Simon C. , Walsh Christopher J. , Hatt Belinda E. 
Published: May 2004

Summary1. Urbanisation is an important cause of eutrophication in waters draining urban areas. We determined whether benthic algal biomass in small streams draining urban areas was explained primarily by small‐scale factors (benthic light, substratum type and nutrient concentrations) within a stream, or by catchment‐scale variables that incorporate the interacting multiple impacts of urbanisation (i.e. variables that describe urban density and the intensity of drainage or septic tank systems).2. Benthic algal biomass was assessed as chlorophyll a density (chl a) in 16 streams spanning a rural–urban gradient, with both a wide range of urban density and of piped stormwater infrastructure intensity on the eastern fringe of metropolitan Melbourne, Australia. The gradient of urban density among streams was broadly correlated with catchment imperviousness, drainage connection (proportion of impervious areas connected to streams by stormwater pipes), altitude, longitude and median phosphorus concentration. Catchment area, septic tank density, median nitrogen concentration, benthic light (photosynthetically active radiation) and substratum type were not strongly correlated with the urban gradient.3. Variation in benthic light and substratum type within streams explained a relatively small amount of variation in log chl a (3–11 and 1–13%, respectively) compared with between‐site variation (39–54%).4. Median chl a was positively correlated with catchment urbanisation, with a large proportion of variance explained jointly (as determined by hierarchical partitioning) by those variables correlated with urban density. Independent of this correlation, the contributions of drainage connection and altitude to the explained variance in chl a were significant.5. The direct connection of impervious surfaces to streams by stormwater pipes is hypothesised as the main determinant of algal biomass in these streams through its effect on the supply of phosphorus, possibly in interaction with stormwater‐related impacts on grazing fauna. Management of benthic algal biomass in streams of urbanised catchments is likely to be most effective through the application of stormwater management approaches that reduce drainage connection.
Comparison of apical transportation between ProFile™ and ProTaper™ NiTi rotary instruments
Authors: Iqbal M. K. , Firic S. , Tulcan J. , Karabucak B. , Kim S. 
Published: May 2004

AbstractAim  To use a newly developed radiographic technique to compare apical transportation and loss of working length (WL) between .06 taper ProFile™ Series 29 and ProTaper™ nickel–titanium (NiTi) rotary instruments in vitro.Methodology  Mesio‐buccal canals of 40 extracted mandibular molars were randomly divided into two groups. Group 1 was instrumented with ProFile™ and group 2 with ProTaper™ instruments according to the manufacturers' directions. A specially constructed radiographic jig with a Schick digital radiographic system (Schick Technologies Inc., Long Island City, NY, USA) was used to take pre‐ and postoperative radiographs of the samples at predetermined angulations. Using AutoCAD 2000 (Autodesk Inc., San Rafael, CA, USA), the central axes of initial and final instruments were radiographically superimposed to determine the loss of WL and degree of transportation at D0, D1, D2 and D4 from the WL. Data were analysed using repeated‐measures anova.Results  A statistically significant difference in apical transportation was found at the D4 level between the two groups (P = 0.05). There was no statistical significance regarding postinstrumentation change in WL between groups. Spearman's Bivariate Correlation analysis indicated no statistically significant relationship between the radius of curvature and transportation.Conclusion  The results indicate that both ProTaper™ and ProFile™ instruments are comparable to each other in regards to their ability to optimally enlarge root canal with minimal transportation and loss of WL in vitro.
Decalcification of root canal dentine by citric acid, EDTA and sodium citrate
Authors: Machado‐Silveiro L. F. , González‐López S. , González‐Rodríguez M. P. 
Published: May 2004

AbstractAim  To measure the demineralization capability of 1 and 10% citric acid, 10% sodium citrate and 17% EDTA during immersions of 5, 10 and 15 min on root canal dentine.Methodology  Crowns were sectioned from eight maxillary canines. The cementum was removed from the cervical third of the roots to expose the dentine. Canals were prepared using a handpiece‐mounted Largo Peeso reamer. A 3‐mm thick cross‐sectional slice was obtained from the cervical third of each root. Each slice was sectioned into four equal parts. These specimens were assigned to one of four groups (n = 8) for the application of 1% citric acid, 10% citric acid, 10% sodium citrate or 17% EDTA. Each specimen underwent three successive 5‐min immersions in each solution at room temperature. The solutions were not renewed between immersions. Two millimetres of solution were collected from the extracts and lanthanum oxide was added for the calcium reading by spectrophotometry. To compare the amounts of calcium removed by each solution, the Friedman test was used for the global comparison and the Wilcoxon test for paired comparisons. Differences between groups were evaluated using the Kruskal–Wallis test for the global comparison and Mann–Whitney test for paired comparisons.Results  Overall, 1 and 10% citric acid were more effective than EDTA or sodium citrate at the three immersion times (P < 0.001); 10% citric acid was more effective than 1% citric acid (P < 0.001). EDTA and 1 and 10% citric acid showed decreasing effectiveness with time, and the decrease was significant for citric acid at both concentrations (P < 0.001). Although sodium citrate removed little calcium during the three time periods, the small increase recorded was significant (P < 0.01).Conclusions  Citric acid at 10% was the most effective decalcifying agent, followed by 1% citric acid, 17% EDTA and 10% sodium citrate.
The influence of root‐end resection and root‐end cavity preparation on microleakage of root filled teeth in vitro
Authors: Kontakiotis E. G. , Lagoudakos T. A. , Georgopoulou M. K. 
Published: May 2004

AbstractAim  To investigate in vitro the influence of root‐end resection and root‐end cavity preparation on leakage of root filled teeth.Methodology  The root canals of 48 roots, 16 mandibular premolars (G1), 16 mandibular incisors (G2) and 16 maxillary incisors (G3), 12 mm in length, were enlarged using a modified ‘balanced force’ technique and filled with gutta‐percha and sealer using lateral compaction. After setting, leakage along the canal was measured using a fluid transport model. Root‐end resection and root‐end cavity preparation were then performed, leaving roots 10 mm in length with root fillings of 7 mm (groups R1, R2 and R3, respectively). Fluid transport was measured again along the remaining root fillings of all groups using the same experimental conditions. Results of leakage before and after root‐end resection were analysed statistically using the Kruskal–Wallis and Wilcoxon tests.Results  A total of 31% of the roots leaked before and 54% after root‐end preparation; the difference was significantly different (P < 0.001). No significant differences were found either among groups G1, G2, G3 (P = 0.565) or among groups R1, R2, R3 (P =0.2628). Significant differences, however, were shown between groups G1–R1 (P = 0.0053), G2–R2 (P =0.0089) and G3–R3 (P = 0.0461).Conclusions  Root‐end resection and root‐end cavity preparation compromised the seal of 7 mm root fillings in all tooth groups. Increased leakage was recorded in the following order: mandibular incisors > mandibular premolars > maxillary incisors.
Unique roles of the rrn P2 rRNA promoters in Escherichia coli
Authors: Murray Heath D. , Gourse Richard L. 
Published: May 2004

SummaryIn bacteria, genes are often expressed from multiple promoters to allow for a greater spectrum of regulation. Transcription of rRNA genes in Escherichia coli uses two promoters, rrn P1 and rrn P2. Under the conditions examined previously, the P1 and P2 promoters were regulated in response to many of the same changes in nutritional conditions. We report here that rrn P2 promoters play unique roles in rRNA expression during transitional situations. rrn P2 promoters play a dominant role in rRNA synthesis as cells enter into and persist in stationary phase. rrn P2 promoters also play a role in the rapid increases in rRNA synthesis that occur during outgrowth from stationary phase and during the initial stages of rapid shifts to richer media. We demonstrate that rrnB P2 directly senses the concentrations of guanosine 5′‐disphosphate 3′‐diphosphate (ppGpp) and the initiating nucleoside triphosphate (iNTP), thereby accounting, at least in part, for the observed patterns of regulation. Our work significantly extends previous information about the regulators responsible for control of the rrn P2 promoters and the relationship between the tandem rRNA promoters.
Bacteriophage T4 endonuclease II: concerted single‐strand nicks yield double‐strand cleavage
Authors: Carlson Karin , Lagerbäck Pernilla , Nyström Anna‐Chey 
Published: May 2004

Summary In vivo, endonuclease II (EndoII) of coliphage T4 cleaves sites with conserved sequence elements (CSEs) to both the left and the right of the cleaved bonds, 16 bp altogether with some variability tolerated. In vitro, however, single‐strand nicks in the lower strand predominate at sites containing only the left‐side CSE that determines the precise position of lower strand nicks. Upper strand nick positions vary both in vivo and in vitro. A 24 bp substrate was nicked with the same precision as in longer substrates, showing that the conserved sequence suffices for precise nicking by EndoII. Using DNA ligase in vitro, we found that EndoII nicked both strands simultaneously at an in vivo‐favoured site but not at an in vitro‐favoured site. This indicates that the right‐side CSE at in vivo‐favoured sites is important for simultaneous nicking of both strands, generating double‐strand cleavage. Separate analysis of the two strands following in vitro digestion at two in vitro‐favoured sites showed that EndoII nicked the lower strand about 1.5‐fold faster than the upper strand. In addition, the upper and lower strands were nicked independently of each other, seldom resulting in double‐strand cleavage. Thus, cleavage by EndoII is the fortuitous outcome of two separate nicking events.
Characterization of the MerD protein from Ralstonia metallidurans CH34: a possible role in bacterial mercury resistance by switching off the induction of the mer operon
Authors: Champier Ludovic , Duarte Victor , Michaud‐Soret Isabelle , Covès Jacques 
Published: May 2004

SummaryMerD and MerR from Tn4378 found in Ralstonia metallidurans CH34 were purified to homogeneity after overexpression in Escherichia coli. Using electrophoretic mobility shift assays and footprinting experiments, we found that MerD cannot bind to DNA. However, in vitro MerD can form a ternary complex in association with merOP and MerR. The presence of MerD in this complex was demonstrated by Western analysis with antibodies to MerD. To our knowledge, this is the first description of such a ternary complex between MerD–MerR and DNA. The formation and stability of this ternary complex are dependent on the relative concentration of the two proteins and modulated by the presence of mercury. We postulate that MerD could displace Hg‐bound MerR from the mer operator to allow new synthesis of metal‐free MerR able to switch off the induction of the mer genes when the external mercury is exhausted. This could fully explain how MerD can be a co‐regulator repressing the induction of the mer operon.
Cleavage‐dependent activation of a chlamydia‐secreted protease
Authors: Dong Feng , Pirbhai Mustak , Zhong Youmin , Zhong Guangming 
Published: May 2004

SummaryA chlamydia‐secreted protein designated CPAF (chlamydial proteasome‐like activity factor) was shown previously to degrade host transcriptional factors (e.g. RFX5) required for major histocompatibility (MHC) gene activation. Although CPAF is encoded by a single open reading frame (ORF) in the chlamydial genome, two fragments designated CPAFn and CPAFc were the main products purified. The current study was designed to test whether cleavage of CPAF into CPAFn and CPAFc is a physiological process required for CPAF proteolytic activity. Pulse–chase experiments revealed that CPAF was initially synthesized in chlamydia‐infected cells as a 70 kDa full‐length protein and rapidly cleaved into CPAFn and c fragments. Full‐length CPAF expressed via a transgene in mammalian cells remained uncleaved and had no proteolytic activity, whereas CPAF expressed in Escherichia coli cells was processed and possessed RFX5 degradation activity. CPAF mutants deficient in processing even when expressed by E. coli failed to degrade RFX5. More importantly, the RFX5 degradation activity was partially restored when the mutant CPAF was artificially induced to undergo cleavage. These observations together have demonstrated that cleavage of CPAF is both necessary and sufficient for CPAF activity.
Encoded errors: mutations and rearrangements mediated by misalignment at repetitive DNA sequences
Authors: Lovett Susan T. 
Published: May 2004

SummaryMutations and rearrangements that occur by misalignment during DNA replication are frequent sources of genetic variation in bacteria. Dislocations between a replicating strand and its template at repetitive DNA sequences underlie the mechanism of these genetic events. Such misalignments can be transient or stable and can involve intramolecular or intermolecular DNA mispairing, even pairing across a replication fork. Paradoxically, these replication ‘slippage’ events both create and destroy repetitive sequences in bacterial genomes. This review catalogues several types of slippage errors, presents the cellular processes that act to limit them and discusses the consequences of this class of genetic events on the evolution of bacterial genomes and physiology.
Characterization of the prion protein gene (PRNP) region in Swiss sheep breeds
Authors: Gmür A. , Gaillard C. , Dolf G. 
Published: May 2004

SummaryPolymorphisms in the PRNP gene have both an influence on the progress of scrapie and also of bovine spongiform encephalopathy (BSE) in sheep. In the light that sheep are potentially susceptible to BSE the goal of this project was to characterize 50 animals of each of the four major Swiss sheep breeds, namely Swiss Oxford Down, Swiss Black‐Brown Mountain, Valais Blacknose and Swiss White Alpine with respect to polymorphisms in the PRNP region. A 628‐bp fragment of exon 3 of PRNP comprising codons 112–211 was amplified by PCR and analysed by direct sequencing. Heterozygous genotypes were further verified by restriction fragment length polymorphism analyses. Polymorphisms could be observed at codons 112, 136, 137, 141, 143, 154 and 171 but not at codons 138, 151 and 211. One of the scrapie cases in Switzerland, a sheep of Swiss White Alpine, was also genotyped. Based on the polymorphisms observed at codons 136, 154 and 171 all four sheep breeds should be considered potentially susceptible to scrapie and BSE.
The Value of Information in the Hold-Up Problem
Authors: Pfeiffer Thomas 
Published: May 2004

Abstract
In the literature, the information structure of the hold-up problem is typically assumed to be exogenous. In this paper, we introduce an additional stage at which the head office may grant individual divisions access to an information system before they undertake their specific investments. Although more information ceteris paribus enhances each divisions’ profits, more information can reduce divisions’ investments and destroy synergies for the other division that would have been generated by the investments. If this negative effect dominates, then information can be harmful for the entire company. Hence, information control can be a subtle force to deal with the hold-up problem to a certain extent. In this paper we analyze those conditions under which information is either harmful or beneficial for central management.
Norway: Madisonianism Reborn
Authors: Narud Hanne Marthe , Strøm Kaare 
Published: May 2004

This article discusses citizen control in Norwegian parliamentary democracy, and specifically the changes that have recently taken place. Around 1960 Norway had reached a constitutional form that, apart from the consequences of proportional representation, looked much like a Westminster system. From that point on, however, Norwegian democracy has generally moved away from this model. A series of minority governments has given rise to parliamentary reassertion. The Norwegian party system has fragmented, and the individual parties have atrophied as mass membership organizations. A wave of corporatism and later a heightened assertiveness on the part of the judiciary have helped to contain parliamentary power. Two critical European Union membership referendums in 1972 and 1994 have firmly established the role of direct democracy in critical political decisions. And despite the results of these two popular consultations, international constraints have become ever more significant.Compared with most others in Europe, however, Norway is a relatively unconstrained polity. There are few important ways in which the citizenry is partitioned into multiple democratic principals, and the country is a reasonable fit to the parliamentary ideal type of an unfettered hierarchy controlled by the median voter. At the same time, the trend is unmistakably one towards greater policy‐making complexity and increasing constraints on policy makers. Norway's reluctant but seemingly inevitable incorporation into a larger Europe is the greatest and most decisive of these constraints, but it is not the only one. Judicial institutions are likely to play an increasingly important political role, and direct democracy perhaps likewise. And although central bank independence has met with greater scepticism than in most other European countries, it is not likely to be reversed. All in all, it seems that Norwegian parliamentary governance is becoming at least a little more Madisonian and a little less Westminsterian.
Perspectives and practice: speech and language therapy student views of an interprofessional learning experience
Authors: Baxter Susan K 
Published: May 2004

AbstractThis article describes a work‐place interprofessional learning experience for Speech and Language Therapy (SLT) students in an acute hospital, using an innovative model of Speech and Language Therapy students learning with students and qualified professionals from other disciplines. The experience was evaluated via a feedback form, use of the Readiness for Interprofessional Learning Scale (RIPLS) and group discussion. The study details feedback on the sessions, with participants reporting greatest benefit in terms of teamwork and collaboration. Student and tutor reflections on the learning experience are outlined and related to broader issues surrounding interprofessional learning in work‐place settings.
Balance Between PGD Synthase and PGE Synthase Is a Major Determinant of Atherosclerotic Plaque Instability in Humans
Authors: Cipollone Francesco , Fazia Maria , Iezzi Annalisa , Ciabattoni Giovanni , Pini Barbara , Cuccurullo Chiara , Ucchino Sante , Spigonardo Francesco , De Luca Mariella , Prontera Cesaria , Chiarelli Francesco , Cuccurullo Franco , Mezzetti Andrea 
Published: May 2004

Objective—Inducible cyclooxygenase (COX-2) catalyzes the first step in prostanoid biosynthesis and is considered a proinflammatory enzyme. COX-2 and type 1 inducible PGE synthase (mPGES-1) have a role in metalloproteinase (MMP) release leading to plaque rupture. In contrast, lipocalin-type PGD synthase (L-PGDS) has been shown to exert antiinflammatory actions. Thus, in this study we investigated whether a shift from a PGDS-oriented to a PGES-oriented profile in arachidonate metabolism leads to inflammatory activation in rupture-prone plaque macrophages.Methods and Results—Atherosclerotic plaques were obtained from 60 patients who underwent carotid endarterectomy, symptomatic (n=30) and asymptomatic (n=30) according to evidence of recent transient ischemic attack or stroke. Plaques were analyzed for COX-2, mPGES-1, L-PGDS, PPARγ, IκBα, NF-κB, and MMP-9 by immunocytochemistry, Western blot, reverse-transcriptase polymerase chain reaction, enzyme immunoassay, and zymography. Prostaglandin E2(PGE2) pathway was significantly prevalent in symptomatic plaques, whereas PGD2pathway was overexpressed in asymptomatic ones, associated with NF-κB inactivation and MMP-9 suppression. In vitro COX-2 inhibition in monocytes was associated with reduced MMP-9 release only when PGD2pathway overcame PGE2pathway.Conclusions—These results suggest that COX-2 may have proinflammatory and antiinflammatory properties as a function of expression of downstream PGH2isomerases, and that the switch from L-PGDS to mPGES-1 in plaque macrophages is associated with cerebral ischemic syndromes, possibly through MMP-induced plaque rupture.
Two Solitudes: The Behaviour of Pigeons in Competitive Feeding
Authors: Sogbein  , Church  , Plowright  , Gagnon  , Potvin  
Published: May 2004

AbstractPrevious research showed that pigeons foraging for preferred grains of maize and less preferred grains of wheat respond to the presence of a competitor by becoming less choosy ( i.e. they more readily choose wheat). We extended this work by disentangling the presence of the competitor from the resource depletion associated with it. In Experiment 1, eight birds foraged for maize and wheat in a flight cage. They were tested both alone and with another bird in different foraging sessions. Two groups were formed and differed in how they were treated when the birds foraged in pairs: both birds had access to food (Both Eat) versus only one bird had access to food (Only One Eats) while the other was placed behind a transparent curtain. For the latter treatment, no effect of the mere presence of the other bird on choice was found. Pigeons were, however, less choosy in the presence of a real competitor that exploited the food. At the end of the experiment, the pigeons that had been tested in the 'Both Eat' treatment, were tested in the 'Only One Eats' treatment. They behaved as if foraging alone. Experiment 2 introduced a new condition in which one bird ate and the other was placed behind the curtain where it pecked at grain but could not eat it. Even though this other bird behaved as if it were a potential competitor, it had no effect on the forager in the pair. The only significant difference in choice proportions was between birds foraging in real competition ( i.e. where the other bird caused resource depletion) or not. In competitive feeding situations, pigeons react to what is most directly associated with the dwindling food conditions but are insensitive to the presence and to the pecking behaviour of the animal that creates them.