bluuebunny/crossref_metadata_2025_split huggingface dataset:
A macroevolutionary mosaic: episodic host‐switching, geographical colonization and diversification in complex host–parasite systems
Authors: Hoberg Eric P. , Brooks Daniel R. 
Published: July 2008

AbstractAim To integrate ecological fitting, the oscillation hypothesis and the taxon pulse hypothesis into a coherent null model for the evolution of complex host–parasite associations.Location Global.Methods This paper reviews and synthesizes literature that focuses on phylogenetic analyses and reciprocal mapping of a model system of hosts and their parasites to determine patterns of host–parasite associations and geographical distributions through time.Results Host‐switching and geographical dispersal of parasites are common phenomena, occurring on many temporal and spatial scales. Diversification involving both co‐evolution and colonization explains complex host–parasite associations. Across the expanse of Earth history, the major radiations in host–parasite assemblages have been preceded by ecological disruption, ecological breakdown and host‐switching in a context that can be defined by the concept of ecological fitting. This cyclical process sets the stage for co‐diversification during periods of relative stability, punctuated by host‐switching during episodes of regional to global environmental disruption and climatological change.Main conclusions Most observed host–parasite associations can be explained by an historical interaction between ecological fitting, oscillation (episodes of increasing host range alternating with isolation on particular hosts) and taxon pulses (cyclical episodes of expansion and isolation in geographical range). Major episodes of environmental change appear to be the main drivers for both the persistence and diversification of host–parasite systems, creating opportunities for host‐switching during periods of geographical expansion and allowing for co‐evolution and co‐speciation during periods of geographical isolation.
Recruitment filters in a perennial grassland: the interactive roles of fire, competitors, moisture and seed availability
Authors: Zimmermann Julia , Higgins Steven I. , Grimm Volker , Hoffmann John , Münkemüller Tamara , Linstädter Anja 
Published: July 2008

Summary

Demographic processes, particularly the recruitment of seedlings, are critical to the long‐term survival and re‐establishment of plant populations. In many perennial grasslands successful recruitment is a rare event that requires the simultaneous favourable alignment of several environmental variables.
Although a few empirical studies have examined demographic processes in perennial grasslands, most of these studies investigate the impact of only one or two environmental factors in isolation. Those studies would lead us to expect that seed availability, irrigation and burning, enhance recruitment rates whereas the presence of established competitors substantially lowers recruitment rates. But how these factors, or recruitment filters, act in concert and how they influence the different components of the recruitment process such as seedling emergence, survival and growth is not understood.
For this reason we explore the relative and combined influence of four factors – seed availability, irrigation, competition by the established vegetation, and fire – on the recruitment process of a perennial grass (Stipagrostis uniplumis) in semi‐arid savanna. We used a full factorial experiment to determine how these four factors influence emergence, growth, survival and flowering of seedlings.
Our results show that all of the factors affected some stage of the recruitment process but not all significant effects contributed to enhancing the final number of recruits.
We found enhanced seed availability to significantly enhance rates of seedling emergence but to play no further role in the recruitment process. Competition by the established vegetation exerted a strong negative effect on every step of the recruitment process. Irrigation had a minor effect on recruitment. It enhanced rates of flowering and survival during the growing season but the effect of the stimulus was short‐lived and did not influence later stages of the recruitment process.
In contradiction to existing theory, seedling recruitment does therefore not seem to be limited to above average rainfall years. Fire acted similarly to the removal of competitors; that is, it positively affected seedling emergence, growth, flowering and survival.
Synthesis. We conclude that recruitment is not limited to above average rainfall years but triggered by events that open up the grass canopy and reduce the abundance of competitors. Specifically it appears that periodic fires enable the recruitment of new individuals into the population. This study shows that fire can play an important positive role in individual turnover of semi‐arid perennial grass populations.
Offering choices to people with intellectual disabilities: an interactional study
Authors: Antaki C. , Finlay W. , Walton C. , Pate L. 
Published: July 2008

AbstractBackground  At the level of policy recommendation, it is agreed that people with intellectual impairments ought to be given opportunities to make choices in their lives; indeed, in the UK, the Mental Capacity Act of 2005 enshrines such a right in law. However, at the level of practice, there is a dearth of evidence as to how choices are actually offered in everyday situations, which must hinder recommendations to change.Method  This qualitative interactional study, based on video recordings in British residential homes, combines ethnography with the fine‐grained methods of Conversation Analysis.Results  We identify six conversational practices that staff use to offer choices to residents with intellectual disabilities.Conclusions  We describe the unwanted consequences of some of these practices, and how the institutional imperative to solicit clear and decisive choice may sometimes succeed only in producing the opposite.
Aspirin and clopidogrel with or without phenprocoumon after drug eluting coronary stent placement in patients on chronic oral anticoagulation
Authors: Sarafoff N. , Ndrepepa G. , Mehilli J. , Dörrler K. , Schulz S. , Iijima R. , Byrne R. , Schömig A. , Kastrati A. 
Published: July 2008

Abstract.Objectives.  Optimal antithrombotic/anticoagulation therapy in patients on chronic oral anticoagulation (OAC) undergoing drug‐eluting stent (DES) implantation is unknown. We investigated the efficacy and safety of two regimens of antithrombotic/anticoagulation therapy in patients who present for DES implantation whilst on OAC.Methods.  We included a series of 515 patients on OAC who underwent DES implantation between 2002 and 2007. Based on predefined clinical and echocardiographic criteria, 306 patients continued OAC (triple therapy) and 209 patients discontinued OAC (dual therapy) for the time they received antiplatelet therapy with clopidogrel and aspirin [stent‐related antithrombotic treatment (SRAT)]. The primary end point was a composite of death, myocardial infarction, stent thrombosis or stroke.Results.  During SRAT the primary endpoint was observed in 13 patients in the group with triple therapy versus 15 patients in the group with dual therapy [Kaplan–Meier estimates 4.2% and 7.2%, odds ratio (OR) = 0.61, 95% confidence interval (CI) 0.29–1.28; P = 0.19]. At 2 years of follow‐up, the primary endpoint was observed in 35 patients in the group with triple therapy versus 36 patients in the group with dual therapy (Kaplan–Meier estimates 14.1% and 18.0%, OR = 0.76, 95% CI: 0.48–1.21; P = 0.25). Two‐year incidence of major bleeding was 1.4% (n = 4, triple therapy) versus 3.1% (n = 6, dual therapy) (P = 0.34).Conclusions.  In patients on chronic OAC undergoing DES implantation, clinical and echocardiographic criteria help to define postprocedural antithrombotic/anticoagulation therapy. Based on these criteria, both a double antiplatelet therapy (clopidogrel plus aspirin) and a triple therapy (OAC plus clopidogrel plus aspirin) are associated with favourable safety and efficacy.
Carbon metabolism of Listeria monocytogenes growing inside macrophages
Authors: Eylert Eva , Schär Jennifer , Mertins Sonja , Stoll Regina , Bacher Adelbert , Goebel Werner , Eisenreich Wolfgang 
Published: July 2008

SummaryThe intracellular metabolism of Listeria monocytogenes was studied by 13C‐isotopologue profiling using murine J774A.1 macrophages as host cells. Six hours after infection, bacteria were separated from the macrophages and hydrolyzed. Amino acids were converted into tert‐butyl‐dimethylsilyl derivatives and subjected to gas chromatography/mass spectrometry. When the macrophages were supplied with [U‐13C6]glucose prior to infection, but not during infection, label was detected only in Ala, Asp and Glu of the macrophage and bacterial protein with equal isotope distribution. When [U‐13C6]glucose was provided during the infection period, 13C label was found again in Ala, Asp and Glu from host and bacterial protein, but also in Ser, Gly, Thr and Val from the bacterial fraction. Mutants of L. monocytogenes defective in the uptake and catabolism of the C3‐metabolites, glycerol and/or dihydroxyacetone, showed reduced incorporation of [U‐13C6]glucose into bacterial amino acids under the same experimental settings. The 13C pattern suggests that (i) significant fractions (50–100%) of bacterial amino acids were provided by the host cell, (ii) a C3‐metabolite can serve as carbon source for L. monocytogenes under intracellular conditions and (iii) bacterial biosynthesis of Asp, Thr and Glu proceeds via oxaloacetate by carboxylation of pyruvate.
System‐level mapping of Escherichia coli response regulator dimerization with FRET hybrids
Authors: Gao Rong , Tao Yuan , Stock Ann M. 
Published: July 2008

SummaryTwo‐component signal transduction, featuring highly conserved histidine kinases (HKs) and response regulators (RRs), is one of the most prevalent signalling schemes in prokaryotes. RRs function as phosphorylation‐activated switches to mediate diverse output responses, mostly via transcription regulation. As bacterial genomes typically encode multiple two‐component proteins for distinct signalling pathways, the sequence and structural similarities of RR receiver domains create significant challenges to maintain interaction specificity. It is especially demanding for members of the OmpR/PhoB subfamily, the largest RR subfamily, which share a conserved dimerization interface for phosphorylation‐mediated transcription regulation. We developed a strategy to investigate RR interaction by analysing Förster resonance energy transfer (FRET) between cyan fluorescent protein (CFP)‐ and yellow fluorescent protein (YFP)‐fused RRs in vitro. Using the Escherichia coli RR PhoB as a model system, we were able to observe phosphorylation‐dependent FRET between fluorescent protein (FP)–PhoB proteins and validated the FRET method by determining dimerization affinity and dimerization‐coupled phosphorylation kinetics that recapitulated values determined by alternative methods. Further application of the FRET method to all E. coli OmpR/PhoB subfamily RRs revealed that phosphorylation–activated RR interaction is indeed a common theme for OmpR/PhoB subfamily RRs and these RRs display significant interaction specificity. Weak hetero‐pair interactions were also identified between several different RRs, suggesting potential cross‐regulation between distinct pathways.
Characterization of the NapGH quinol dehydrogenase complex involved in Wolinella succinogenes nitrate respiration
Authors: Kern Melanie , Simon Jörg 
Published: July 2008

SummaryNitrate respiration catalysed by the ε‐proteobacterium Wolinella succinogenes relies on the NapAGHBFLD system that comprises periplasmic nitrate reductase (NapA) and various other Nap proteins required for electron transport from menaquinol to NapA or maturation of Nap components. The W. succinogenes Nap system is unusual as electron transfer to NapA was shown previously to depend on both subunits of the predicted menaquinol dehydrogenase complex NapGH but did not require a cytochrome c of the NapC/NrfH family. Nonetheless, minor residual growth by nitrate respiration was observed in napG and napH gene inactivation mutants. Here, the question is addressed whether alternative membrane‐bound menaquinol dehydrogenases, like NrfH and NosGH, involved in nitrite or N2O reduction systems, are able to functionally replace NapGH. The phenotypes of various gene deletion mutants as well as strains expressing chimeric nap/nos operons demonstrate that NosH is able to donate electrons to the respiratory chain of nitrate respiration at a physiologically relevant rate, whereas NrfH and NosG are not. The iron‐sulphur protein NapG was shown to form a complex with NapH in the membrane but was detected in the periplasmic cell fraction in the absence of NapH. Likewise, NosH is able to bind NapG. Each of the eight poly‐cysteine motifs present in either NapG or NapH was shown to be essential for nitrate respiration. The NapG homologue NosG could not substitute for NapG, even after adjusting the cysteine spacing to that of NapG, implying that NapG and NosG are specific adapter proteins that channel electrons into either the Nap or Nos system. The current model on the structure and function of the NapGH menaquinol dehydrogenase complex is presented and the composition of the electron transport chains that deliver electrons to periplasmic reductases for either nitrate, nitrite or N2O is discussed.
Effect of Specific Colostral Antibodies and Selected Lactobacilli on the Adhesion of Helicobacter pylori on AGS Cells and the Helicobacter‐Induced IL‐8 Production
Authors: Rokka S. , Myllykangas S. , Joutsjoki V. 
Published: July 2008

Abstract Helicobacter pylori infection is the most common cause of gastritis, gastric ulcer and adenocarcinoma. It has proven difficult to cure because of its capability to develop strains resistant to antibiotics. The effect of three strains of lactic acid bacteria (LAB) and bovine colostral preparations on the adhesion of H. pylori NCTC 11637 on gastric adenocarcinoma (AGS) cells and on the interleukin (IL)‐8 production was studied. Before infection, H. pylori were pretreated with Lactobacillus plantarum MLBPL1, Lactobacillus rhamnosus GG, Lactococcus lactis, or with a colostral preparation with or without specific H. pylori antibodies. The relative number of H. pylori adhered on AGS cells was determined by urease test. IL‐8 produced by the cells was studied by enzyme‐linked immunosorbent assay. Colostral preparations with and without specific antibodies reduced the adhesion of H. pylori on AGS cells in a dose‐dependent manner. Live LAB at a concentration of 1010 CFU/ml reduced the adhesion by approximately 50% (P < 0.05). After the infection of AGS cells by H. pylori, the IL‐8 level rose up to about 10‐fold (5500 ± 1600 pg/ml). Pretreatment of H. pylori with colostral preparations or high concentrations of LAB prevented this IL‐8 rise. Similar effect was seen with live and heat‐killed LAB, the live LAB being more effective. Heat‐killed LAB at a concentration of 1010 CFU/ml rose the IL‐8 level of non‐infected cells significantly. Suppression of IL‐8 production by LAB or colostral products could have a suppressive effect on inflammation in Helicobacter infection.
Shallow lacustrine carbonate microfacies document orbitally paced lake‐level history in the Miocene Teruel Basin (North‐East Spain)
Authors: ABELS HEMMO A. , ABDUL AZIZ HAYFAA , CALVO JOSÉ P. , TUENTER ERIK 
Published: July 2008

AbstractResults are presented of a detailed carbonate petrographic study of an Upper Miocene lacustrine mixed carbonate–siliciclastic succession in the Teruel Basin (Spain) with the aim of constraining lake‐level variability at different stratigraphic scales. Regular alternations of red to green mudstone and lacustrine limestone, termed the ‘basic cycle’, reflect lake‐level variations at the metre‐scale. In an earlier study, the basic cycle was shown to be controlled by the climatic precession cycle. Petrographic analysis made it possible to distinguish two main carbonate microfacies groups characteristic of very shallow transient and shallow permanent lake environments, respectively. In addition to the basic cyclicity, the microfacies analysis reveals lake‐level variations on a larger scale. As a consequence, the astronomical forcing hypothesis of the cyclicity in the Cascante section is explored further. A climate modelling study of orbital extremes indicates that high lake levels could relate to enhanced net winter precipitation and runoff during precession minima, consistent with Mediterranean geological data. Using this phase relationship, an astronomical tuning of the cycles is established starting from astronomical ages of magnetic reversal boundaries. Subsequently, successive basic cycles are correlated to precession minima. The tuning reveals an identical number of basic cycles in the Cascante section as precession‐related sapropel cycles in the deep marine succession at Monte dei Corvi (Italy), corroborating the precessional control of the basic cycles at Cascante. Lake‐level highstands in the large‐scale cycle identified by the microfacies analysis relate to maxima in both the ca 100 and 405 kyr eccentricity cycles, again consistent with Mediterranean geological data. Subtraction of the identified astronomically related (lake‐level) variations from the palaeoenvironmental record at Cascante indicates a shift to deeper and more permanent lacustrine environments in the upper half of the section. The cause of this shift remains unclear, but it may be linked to tectonics, non‐astronomical climate, long‐period astronomical cycles or autogenic processes.
Thermochemical sulphate reduction in the Upper Devonian Cairn Formation of the Fairholme carbonate complex (South‐West Alberta, Canadian Rockies): evidence from fluid inclusions and isotopic data
Authors: VANDEGINSTE VEERLE , SWENNEN RUDY , GLEESON SARAH A. , ELLAM ROB M. , OSADETZ KIRK , ROURE FRANÇOIS 
Published: July 2008

AbstractThe Fairholme carbonate complex is part of the extensively dolomitized Upper Devonian carbonate reefs in west‐central Alberta. The studied formations contain moulds (up to 10 cm in diameter), which are filled partially with (saddle) dolomite, quartz and calcite cements. These cements precipitated from a mixture of brines that acquired high salinity by dissolution of halite and brines derived from evaporated sea water. The fluids were warm (homogenization temperature of primary fluid inclusions of 76 to 200 °C) and saline (20 to 25 wt% NaCl equivalent) and testify to thermochemical sulphate reduction processes. The latter is deduced from S in solid inclusions, CO2 and H2S in volatile‐rich aqueous inclusions and depleted δ13C values down to −26‰ Vienna Pee Dee Belemnite. High 87Sr/86Sr values (0·7094 to 0·7110) of the cements also indicate interaction of the fluids with siliciclastic sequences. The thermochemical sulphate reduction‐related cements probably formed during early Laramide burial. Another (younger) calcite phase, characterized by depleted δ18O values (−23·9‰ to −13·9‰ Vienna Pee Dee Belemnite), low Na (27 to 37 p.p.m.) and Sr (39 to 150 p.p.m.) concentrations and non‐saline (∼0 wt% NaCl equivalent) fluid inclusions, is attributed to post‐Laramide meteoric water.
The effect of otic vehicle and concentration of dexamethasone on liver enzyme activities and adrenal function in small breed healthy dogs
Authors: Aniya Jennifer S. , Griffin Craig E. 
Published: July 2008

AbstractDexamethasone 0.1% in propylene glycol vehicle has been shown to cause adrenal suppression and increased liver enzyme concentrations in normal dogs. The objectives of this study were to determine if these effects are concentration or vehicle dependent and to evaluate a dexamethasone 0.01% solution. Twenty‐one privately owned normal dogs were included in this double‐blinded study. Chemistry panels and adrenocorticotropin hormone (ACTH) stimulation tests were performed on day 0 and 15. Dogs were randomly assigned treatment with dexamethasone 0.01% in saline, 0.1% in saline, or 0.1% in a commercial preparation (Tresaderm®: Merial, Duluth, GA, USA) in each ear twice daily for 2 weeks. Nineteen dogs completed the study. After 2 weeks of treatment, all dogs receiving dexamethasone 0.01% in saline had normal ACTH stimulation tests and liver enzyme values. In contrast, four of seven dogs (57.14%) receiving dexamethasone 0.1% in saline experienced adrenal suppression, and four of six dogs (66.67%) receiving Tresaderm® experienced adrenal suppression with three of those dogs (50%) experiencing marked adrenal suppression. No dogs receiving dexamethasone 0.1% in saline had increased liver enzyme concentration, while one of six dogs (16.67%) experienced a slight elevation in alkaline phosphatase. In conclusion, it appears that adrenal suppression caused by otic dexamethasone is concentration and perhaps vehicle dependent. Veterinarians who formulate dexamethasone 0.1% otic solutions should be cognizant of potential adrenal suppression similar to that seen with Tresaderm® although not to the same degree. Dexamethasone at 0.01% did not cause adrenal suppression or liver enzyme alterations after 2 weeks of treatment.
Mouse allergen exposure, wheeze and atopy in the first seven years of life
Authors: Phipatanakul W. , Celedón J. C. , Hoffman E. B. , Abdulkerim H. , Ryan L. M. , Gold D. R. 
Published: July 2008

Background:  Little is known about mouse allergen exposure in home environments and the development of wheezing, asthma and atopy in childhood.Objective:  To examine the relation between mouse allergen exposure and wheezing, atopy, and asthma in the first 7 years of life.Methods:  Prospective study of 498 children with parental history of allergy or asthma followed from birth to age 7 years, with longitudinal questionnaire ascertainment of reported mouse exposure and dust sample mouse urinary protein allergen levels measured at age 2–3 months.Results:  Parental report of mouse exposure in the first year of life was associated with increased risk of transient wheeze and wheezing in early life. Current report of mouse exposure was also significantly associated with current wheeze throughout the first 7 years of life in the longitudinal analysis (P = 0.03 for overall relation of current mouse to current wheeze). However, early life mouse exposure did not predict asthma, eczema or allergic rhinitis at age 7 years. Exposure to detectable levels of mouse urinary protein in house dust samples collected at age 2–3 months was associated with a twofold increase in the odds of atopy (sensitization to >=1 allergen) at school age (95% confidence interval for odds ratio = 1.1–3.7; P = 0.03 in a multivariate analysis.Conclusions:  Among children with parental history of asthma or allergies, current mouse exposure is associated with increased risk of wheeze during the first 7 years of life. Early mouse exposure was associated with early wheeze and atopy later in life.