bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of temperature on viscosity of root canal sealers
Authors: Lacey S. , Pitt Ford T. R. , Yuan X.‐F. , Sherriff M. , Watson T. 
Published: August 2006

AbstractAim  To test the hypothesis that there was no significant (α = 0.05) change in viscosity of commercially available root canal sealers with increase in temperature using a high‐performance Advanced Rheometric Expansion System (ARES) rheometer.Methodology  Materials tested were Apexit, Tubliseal EWT, Grossman's, AH Plus and Ketac‐endo. Cone‐and‐plate geometry was used (25‐mm diameter, 0.1 radian and gap 0.051 mm). Measurements were carried out for steady‐state viscosity at 25 and 37 °C in the shear rate range of 0.001–50 s−1 at standardized relative humidity and within 30 min from the start of mixing. Five samples were taken for each sealer at each temperature.Results  At 25 °C all sealers demonstrated shear thinning. At 37 °C Grossman's (powder : liquid ratio 2 : 1 and 3 : 1) and Ketac‐endo had a rapid rise in viscosity and early set whereas the other sealers were shear thinning. On increasing temperature from 25 °C to 37 °C, Apexit, Tubliseal and AH Plus had reduced viscosity whereas Grossman's 2 : 1, Grossman's 3 : 1 and Ketac‐endo had increased viscosity, which varied with the shear rate. The change in viscosity with change in temperature was significant (P < 0.05) for all sealers except AH Plus.Conclusions  There was a variation in the effect of increasing temperature on each sealer depending on the shear rate. With the exception of AH Plus, a significant (P < 0.05) change in viscosity was found, and the null hypothesis was rejected.
In vitro antimicrobial activity of sodium hypochlorite and chlorhexidine against selected single‐species biofilms
Authors: Sena N. T. , Gomes B. P. F. A. , Vianna M. E. , Berber V. B. , Zaia A. A. , Ferraz C. C. R. , Souza‐Filho F. J. 
Published: August 2006

AbstractAim  To investigate the antimicrobial activity of 2.5% and 5.25% sodium hypochlorite and 2.0% chlorhexidine gel and liquid as endodontic‐irrigating substances against selected single‐species biofilms.Methods  Single‐species biofilms of Enterococcus faecalis, Staphylococcus aureus, Candida albicans, Prevotella intermedia, Porphyromonas gingivalis, Porphyromonas endodontalis and Fusobacterium nucleatum were generated on a cellulose nitrate membrane placed on agar medium. The biofilms were then immersed in the endodontic‐irrigating substances for 30 s and also for 5, 10, 15, 30 and 60 min, with and without mechanical agitation. Sterile saline was used as control. After each time period, the membrane filters were then transferred to tubes containing 2 mL of fresh broth medium plus neutralizers (in order to prevent the residual action of the tested substances). The micro‐organisms were suspended using a vortex, and the inoculum was serially diluted 10‐fold. Aliquots of the dilutions were plated on 5% sheep blood agar medium, and incubated under adequate gaseous conditions. Colony‐forming units were calculated. The samples were compared using the Friedman and Tukey test, when necessary, at a significance level of P < 0.05.Results  Mechanical agitation promoted the effectiveness of the antimicrobial agents, resulting in less time to eliminate the same micro‐organisms, except for S. aureus with 2.5% NaOCl. Antimicrobial agents in liquid presentation, especially 5.25% NaOCl and 2% chlorhexidine, killed the tested micro‐organisms more rapidly. Saline did not inhibit the growth of any of the tested micro‐organisms, with or without agitation, being statistically different (P < 0.05) from NaOCl and chlorhexidine. P. intermedia, P. gingivalis, P. endodontalis and F. nucleatum were eliminated in 30 s by all antimicrobial agents, with our without agitation, in contrast with the facultative and aerobe strains.Conclusions  Mechanical agitation improved the antimicrobial properties of the chemical substances tested using a biofilm model, favouring the agents in liquid presentation, especially 5.25% NaOCl and 2% chlorhexidine.
Survival of root filled cracked teeth in a tertiary institution
Authors: Tan L. , Chen N. N. , Poon C. Y. , Wong H. B. 
Published: August 2006

AbstractAim  To assess the survival rate of root filled cracked teeth over a 2‐year period in a tertiary institute.Methodology  Forty‐nine patients who had root canal treatment completed on their cracked teeth at the National Dental Centre (Singapore) were recalled for a 2‐year review. Collected review data included presence of periodontal pocketing, sinus tract and swelling associated with the teeth. The date of extraction was noted if a tooth was missing at review. Pre‐treatment data collected were number, extent and location of crack, presence of periodontal pocketing, patients’ age and gender, location of cracked teeth, type of teeth and presence of terminal cracked tooth.Results  Fifty teeth in 49 patients were included. The Kaplan–Meier estimate of 2‐year survival rate was 85.5% (95% confidence interval: 75.5–95.5). Cracked teeth which were the terminal teeth in the dental arch (RR = 4.9, 95% CI: 1.2–2.0, P = 0.04), teeth with pre‐root filling periodontal pocketing (RR = 4.9, 95% CI: 1.2–2.0, P = 0.04) and teeth with multiple cracks (RR = ∞, 95% CI: 1.9–∞, P = 0.01) were more likely to be extracted.Conclusions  Within the limitations of this study, multiple cracks, terminal teeth and pre‐root filling pocketing were significant prognostic factors for the survival of root filled cracked teeth.
Early exposure to smoking and future fecundity among Danish twins
Authors: Jensen T. K. , Joffe M. , Scheike T. , Skytthe A. , Gaist D. , Petersen I. , Christensen K. 
Published: August 2006

SummarySeveral studies have examined the effect of in utero exposure to smoking and fecundity among the offspring but the findings are contradictory. We therefore studied the waiting time to first pregnancy (TTP) and exposure to smoking in utero and childhood among Danish twins born between 1931 and 1952. Information about TTP, exposure to mothers smoking in pregnancy, exposure to smoking in childhood and current smoking among the male twins and smoking in their own pregnancy among female twins was collected by interview. Fecundability odds ratio (FOR) estimating the odds of conception in a cycle among exposed compared to the unexposed were calculated separately for female and male twins. A total of 1653 female and 1598 male twins reported a TTP. Female twins, exposed in utero, had reduced fecundability after control for confounders (FOR = 0.81; 95% CI 0.67–0.99). A nonsignificant increase in fecundity among male twins exposed to smoking in utero was found (FOR = 1.12; 95% CI 0.89–1.40). Among dizygotic twins of opposite sex sharing the same in utero exposures, the future fecundity of the male twin was unaffected by in utero exposure (FOR = 0.97; 95% CI 0.60–1.55) whereas the female twin had reduced fecundity (FOR = 0.65; 95% CI 0.47–0.91). This study supports that smoking is hazardous to the female fetus not only in the short term but also affects her future ability to conceive and makes it even more important to advise pregnant women to stop smoking.
The biogeography of naturalization in alien plants
Authors: Pyšek Petr , Richardson David M. 
Published: August 2006

AbstractAim This paper reviews the main geographical determinants of naturalization in plants.Location Global.Methods Comparative studies of large data sets of alien floras are the main source of information on global patterns of naturalization.Results Temperate mainland regions are more invaded than tropical mainland regions but there seems to be no difference in invasibility of temperate and tropical islands. Islands are more invaded than the mainland. The number of naturalized species in temperate regions decreases with latitude and their geographical ranges increase with latitude. The number of naturalized species on islands increases with temperature. Naturalized species contribute to floristic homogenization, but the phenomenon is scale‐dependent.Main conclusions Some robust patterns are evident from currently available data, but further research is needed on several aspects to advance our understanding of the biogeography of naturalization of alien plants. For example, measures of propagule pressure are needed to determine the invasibility of communities/ecosystems/regions. The patterns discussed in this paper are derived largely from numbers and proportions of naturalized species, and little is known about the proportion of introduced species that become naturalized. Further insights on naturalization rates, i.e. the proportion of aliens that successfully naturalize within regions, and on geographical and other determinants of its variation would provide us with better understanding of the invasion process. Comparative studies, and resulting generalizations, are almost exclusively based on numbers of species, but alien species differ in their impact on native biodiversity and ecosystem processes.
Hyperthermia is a surrogate marker of inflammation‐mediated cause of brain damage in acute ischaemic stroke
Authors: LEIRA R. , RODRÍGUEZ‐YÁÑEZ M. , CASTELLANOS M. , BLANCO M. , NOMBELA F. , SOBRINO T. , LIZASOAIN I. , DÁVALOS A. , CASTILLO J. 
Published: August 2006

Abstract.The influence of temperature on the outcome observed in experimental models of ischaemic stroke has not been definitively proved in patients with stroke. Interleukin‐6 (IL‐6) acts as important endogenous pyrogen, and it is an important regulator of spontaneous body temperature during cerebral ischaemia. The objective of this study was to determine, during the acute phase of cerebral ischaemia, the potential relationship between proinflammatory cytokines and hyperthermia as a cause of larger cerebral infarcts.Patients and methods.  We studied 229 patients with a first‐ever acute hemispheric infarction admitted within the first 24 h from onset of symptoms. On admission, axillary temperature was recorded and blood chemistry studies and cranial computed tomography were performed. We classified body temperature into two groups: hyperthermia (37.5 °C) and normothermia (<37.5 °C). We determined proinflammatory markers [IL‐6, tumour necrosis factor‐α (TNF‐α), intercellular adhesion molecule (ICAM‐1) and vascular cellular adhesion molecule] on admission. Two outcome variables were evaluated: (i) infarct volume; (ii) Canadian Stroke Scale (CSS) at 3 months (CSS  7 was considered poor outcome and CSS > 7 good outcome).Results.  Patients with hyperthermia had higher infarct volume [46.5 (9.8–78.5) cm3 vs. 19.1 (5.0–23.5) cm3; P < 0.0001], as well as poor outcome at 3 months. Plasma levels of IL‐6, TNF‐α and ICAM‐1 were significantly higher in the group of patients with hyperthermia than in the normothermic group. There was a significant correlation between body temperature on admission and infarct volume (r = 0.302; P < 0.0001), and between proinflammatory markers (IL‐6 and TNF‐α) and infarct volume. A significant association was also found between proinflammatory markers (IL‐6, TNF‐α, and ICAM‐1) and poor outcome. However, after adjustment for potential confounders, hyperthermia was not independently associated with either larger infarct volume or with poor outcome at 3 months.Conclusions.  Inflammatory mediators play a role in acute ischaemic brain damage independently of hyperthermia.
Clinical aspects of parvovirus B19 infection
Authors: BROLIDEN K. , TOLFVENSTAM T. , NORBECK O. 
Published: August 2006

Abstract.Parvovirus B19 is a significant human pathogen that causes a wide spectrum of clinical complications ranging from mild, self‐limiting erythema infectiosum in immunocompetent children to lethal cytopenias in immunocompromised patients and intrauterine foetal death in primary infected pregnant women. The infection may also be persistent and can mimic or trigger autoimmune inflammatory disorders. Another important clinical aspect to consider is the risk of infection through B19‐contaminated blood products. Recent advances in diagnosis and pathogenesis, new insights in the cellular immune response and newly discovered genotypes of human parvoviruses form a platform for the development of modern therapeutic and prophylactic alternatives.
A genomic scan for divergent selection in a secondary contact zone between Atlantic and Gulf of Mexico oysters,Crassostrea virginica
Authors: MURRAY MARIA C. , HARE MATTHEW P. 
Published: August 2006

AbstractThe degree of population structure within species often varies considerably among loci. This makes it difficult to determine whether observed variance reflects neutral‐drift stochasticity or locus‐specific selection at one or more loci. This uncertainty is exacerbated when evolutionary equilibrium cannot be assumed and/or admixture potentially inflates genomic variance. Thus, the value of a ‘genome scan’, where locus‐specific summary statistics are compared with a simulated neutral distribution among loci, may be limited in secondary contact zones if the null distribution is sensitive to the timing of secondary contact. Of particular interest here is the wide variance previously observed in locus‐specific patterns of population structure between Atlantic and Gulf of Mexico populations of eastern oyster,Crassostrea virginica. To test the robustness of an equilibrium null model, we compared among‐locus distributions ofFSTsimulated under migration‐drift equilibrium and several nonequilibrium secondary contact histories. We then tested for evidence of divergent selection between two oyster populations on either side of a secondary contact zone using 215 amplified fragment length polymorphism (AFLP) loci. Constant‐migration equilibrium and nonequilibrium secondary‐contact simulations produced equivalent distributions ofFSTwhen anchored by the global meanFSTobserved in oysters, 0.0917. The 99th quantile of simulated neutralFSTencompassed most of the variation among oyster loci. Three AFLP loci exhibitedFSTvalues higher than this threshold. Although no locus was significant after correcting for multiple tests, our results show in geographically clinal organisms: AFLPs can efficiently characterize the genomic distribution ofFST; equilibrium models can be used to evaluate outliers; these procedures help focus research on genomic regions of interest.
Site‐specific genetic divergence in parallel hybrid zones suggests nonallopatric evolution of reproductive barriers
Authors: PANOVA M. , HOLLANDER J. , JOHANNESSON K. 
Published: August 2006

AbstractThe evolution of reproductive isolation in the presence of gene flow is supported by theoretical models but rarely by data. Empirical support might be gained from studies of parallel hybrid zones between interbreeding taxa. We analysed gene flow over two hybrid zones separating ecotypes ofLittorina saxatilisto test the expectation that neutral genetic markers will show site‐specific differences if barriers have evolvedin situ. Distinct ecotypes found in contrasting shore habitats are separated by divergent selection and poor dispersal, but hybrid zones appear between them. Swedish islands formed by postglacial uplift 5000 years ago provide opportunities to assess genetic structure in a recently evolved system. Each island houses a discrete population containing subpopulations of different ecotypes. Hybrid zones between ecotypes may be a product of ecological divergence occurring on each island or a consequence of secondary overlap of ecotypes of allopatric origin that have spread among the islands. We used six microsatellite loci to assess gene flow and genetic profiles of hybrid zones on two islands. We found reduced gene flow over both hybrid zones, indicating the presence of local reproductive barriers between ecotypes. Nevertheless, subpopulations of different ecotypes from the same island were genetically more similar to each other than were subpopulations of the same ecotype from different islands. Moreover, neutral genetic traits separating the two ecotypes across hybrid zones were site‐specific. This supports a scenario ofin situorigin of ecotypes by ecological divergence and nonallopatric evolution of reproductive barriers.
Genetic divergence in the small Indian mongoose (Herpestes auropunctatus), a widely distributed invasive species
Authors: THULIN CARL‐GUSTAF , SIMBERLOFF DANIEL , BARUN ARIJANA , MCCRACKEN GARY , PASCAL MICHEL , ISLAM M. ANWARUL 
Published: August 2006

AbstractThe combination of founder events, random drift and new selective forces experienced by introduced species typically lowers genetic variation and induces differentiation from the ancestral population. Here, we investigate microsatellite differentiation between introduced and native populations of the small Indian mongoose (Herpestes auropunctatus). Many expectations based on introduction history, such as loss of alleles and relationships among populations, are confirmed. Nevertheless, when applying population assignment methods to our data, we observe a few specimens that are incorrectly assigned and/or appear to have a mixed ancestry, despite estimates of substantial population differentiation. Thus, we suggest that population assignments of individuals should be viewed as tentative and that there should be agreement among different algorithms before assignments are applied in conservation or management. Further, we find no congruence between previously reported morphological differentiation and the sorting of microsatellite variation. Some introduced populations have retained much genetic variation while others have not, irrespective of morphology. Finally, we find alleles from the sympatric grey mongoose (Herpestes edwardsii) in one small Indian mongoose within the native range, suggesting an alternative explanation for morphological differentiation involving a shift in female preferences in allopatry.
Nearshore fish (Pholis gunnellus) persists across the North Atlantic through multiple glacial episodes
Authors: HICKERSON M. J. , CUNNINGHAM C. W. 
Published: August 2006

AbstractThe intertidal biota of the North Atlantic is characterized by two disjunct communities (North American and European) exposed to different climatic regimes during the Pleistocene and in the Holocene. We collect multilocus DNA sequence data from the nearshore fish Pholis gunnellus to help uncover processes determining biogeographical persistence during periodic coastal glaciations. Coalescent‐based estimates from the multilocus DNA sequence data suggest that P. gunnellus persisted on both sides of the North Atlantic throughout the last two glacial maxima (> 202 000 years) with little trans‐Atlantic gene flow since divergence, very little structure among populations within Europe (ΦST < 0.05) and some structure within the North American coastline (ΦST = 0.0–0.21). Although the ecological flexibility and high local migration of P. gunnellus could have enhanced this species’ survival across the Atlantic, logistic regression did not find a significant determinant of trans‐Atlantic persistence when considering 12 other North Atlantic phylogeographical studies from the literature.
Genetic structure of the star sea squirt, Botryllus schlosseri, introduced in southern European harbours
Authors: LÓPEZ‐LEGENTIL SUSANNA , TURON XAVIER , PLANES SERGE 
Published: August 2006

AbstractThe introduction of new genetic variants or species is often caused by maritime transport between harbours. Botryllus schlosseri is a cosmopolitan ascidian species that is found in both harbours and open shore habitats. In order to determine the influence of ship traffic on the genetic structure and phylogeography of B. schlosseri in southern Europe, we analyzed the variability of a fragment of the mitochondrial gene cytochrome c oxidase subunit I (COI). We sampled seven Atlanto‐Mediterranean harbour populations and three open‐shore populations. In addition, we sequenced some colonies from the US‐Atlantic coast and from other Mediterranean localities to perform phylogenetic analyses. Although the number of polymorphic sites recorded (25.8%) was within the range observed in other population studies based on ascidian COI sequences, the haplotypic diversity (16 haplotypes out of 181 sequences) was much lower. Moreover, a lack of intermediate haplotypes was observed. This pattern of high nucleotide diversity and low haplotype diversity was consistent with introduction events of a few divergent haplotypes. We found a strong genetic structure in the study populations. Gene flow was only appreciable between some harbour populations. Harbour‐ and open‐shore populations were well differentiated, although there was no evidence for isolation by distance. A nested clade analysis pointed to long‐distance colonization, possibly coupled with subsequent fragmentation, as the underlying process. Our results suggest that B. schlosseri entered the study area via harbour‐hopping, possibly through recurrent introduction events. The haplotypes from North America and most of the European ones were grouped in the same phylogenetic clade. This suggests occasional gene flow between both continents, probably through ship transport.
From genes to geography: a genetic similarity rule for arthropod community structure at multiple geographic scales
Authors: BANGERT R. K. , ALLAN G. J. , TUREK R. J. , WIMP G. M. , MENESES N. , MARTINSEN G. D. , KEIM P. , WHITHAM T. G. 
Published: August 2006

AbstractWe tested the hypothesis that leaf modifying arthropod communities are correlated with cottonwood host plant genetic variation from local to regional scales. Although recent studies found that host plant genetic composition can structure local dependent herbivore communities, the abiotic environment is a stronger factor than the genetic effect at increasingly larger spatial scales. In contrast to these studies we found that dependent arthropod community structure is correlated with both the cross type composition of cottonwoods and individual genotypes within local rivers up to the regional scale of 720 000 km2 (Four Corner States region in the southwestern USA). Across this geographical extent comprising two naturally hybridizing cottonwood systems, the arthropod community follows a simple genetic similarity rule: genetically similar trees support more similar arthropod communities than trees that are genetically dissimilar. This relationship can be quantified with or without genetic data in Populus.
The tandem GTPase, Der, is essential for the biogenesis of 50S ribosomal subunits in Escherichia coli
Authors: Hwang Jihwan , Inouye Masayori 
Published: August 2006

SummaryA unique GTP‐binding protein, Der contains two consecutive GTP‐binding domains at the N‐terminal region and its homologues are highly conserved in eubacteria but not in archaea and eukaryotes. In the present paper, we demonstrate that Der is one of the essential GTPases in Escherichia coli and that the growth rate correlates with the amount of Der in the cell. Interestingly, both GTP‐binding domains are required at low temperature for cell growth, while at high temperature either one of the two domains is dispensable. Result of the sucrose density gradient experiment suggests that Der interacts specifically with 50S ribosomal subunits only in the presence of a GTP analogue, GMPPNP. The depletion of Der accumulates 50S and 30S ribosomal subunits with a concomitant reduction of polysomes and 70S ribosomes. Notably, Der‐depleted cells accumulate precursors of both 23S and 16S rRNAs. Moreover, at lower Mg2+ concentration, 50S ribosomal subunits from Der‐depleted cells are further dissociated into aberrant 50S ribosomal subunits; however, 30S subunits are stable. It was revealed that the aberrant 50S subunits, 40S subunits, contain less ribosomal proteins with significantly reduced amounts of L9 and L18. These results suggest that Der is a novel 50S ribosome‐associated factor involved in the biogenesis and stability of 50S ribosomal subunits. We propose that Der plays a pivotal role in ribosome biogenesis possibly through interaction with rRNA or rRNA/r–protein complex.