bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Antimicrobial Dosage Regimen onSalmonellaandEscherichia coliIsolates from Feeder Swine
Authors: Wagner Bruce A. , Straw Barbara E. , Fedorka-Cray Paula J. , Dargatz David A.
Published: January 2008

A body of evidence exists that suggests that antimicrobial use in food animals leads to resistance in both pathogenic and commensal bacteria. This study focused on the impact of three different antimicrobial regimes (low-level continuous, pulse, and no antimicrobial) for two antimicrobials (chlortetracycline and tylosin) on the presence ofSalmonellaspp. and on the prevalence of antimicrobial resistance of bothSalmonellaspp. and nonspecificEscherichia coliin fecal samples from feeder swine. The prevalence of fecal samples positive forSalmonellaspp. significantly decreased between the samples taken at feeder placement compared to samples taken when the animals were close to market weight. Differences in resistance ofSalmonellaspp. did not appear to be influenced by dosing treatment including the control. Analysis of antimicrobial resistance examining both susceptibility and resistance, as well as MIC outcomes, demonstrated that only resistance to cephalothin increased inE. coliunder the pulse chlortetracycline treatment. These results suggest that the dosing regimes examined in this study did not lead to an increase in either the prevalence ofSalmonellaspp. or the prevalence of antimicrobial resistance in isolates ofSalmonellaspp. orE. coli.
Mucin Degradation by
Bifidobacterium
Strains Isolated from the Human Intestinal Microbiota
Authors: Ruas-Madiedo Patricia , Gueimonde Miguel , Fernández-García María , de los Reyes-Gavilán Clara G. , Margolles Abelardo
Published: January 2008

The presence of the genes
engBF
(
endo
-α-
N
-acetylgalactosaminidase) and
afcA
(1,2-α-
l
-fucosidase) was detected in several intestinal
Bifidobacterium
isolates. Two strains of
Bifidobacterium bifidum
contained both genes, and they were able to degrade high-molecular weight porcine mucin in vitro. The expression of both genes was highly induced in the presence of mucin.
Genetic Modulation of the Overexpression of Tailoring Genes
eryK
and
eryG
Leading to the Improvement of Erythromycin A Purity and Production in
Saccharopolyspora erythraea
Fermentation
Authors: Chen Yun , Deng Wei , Wu Jiequn , Qian Jiangchao , Chu Ju , Zhuang Yingping , Zhang Siliang , Liu Wen
Published: January 2008

Erythromycin A (Er-A) is the most potent and clinically important member in the Er family produced by
Saccharopolyspora erythraea
. Er-B and Er-C, which are biologically much less active and cause greater side effects than Er-A, serve as the intermediates for Er-A biosynthesis and impurities in fermentation processes of many industrial strains. In this study, systematical modulation of the amounts of tailoring enzymes EryK (a P450 hydroxylase) and EryG (an
S
-adenosylmethionine-dependent
O
-methyltransferase) was carried out by genetic engineering in
S. erythraea
, including alterations of gene copy number ratio and organization and integrating the locus on the chromosome by homologous recombination. Introduction of additional
eryK
and
eryG
genes into
S. erythraea
showed significant impacts on their transcription levels and enhanced the biotransformation process from Er-D to Er-A with gene dose effects. At the
eryK
/
eryG
copy number ratio of 3:2 as well as their resultant transcript ratio of around 2.5:1 to 3.0:1, Er-B and Er-C were nearly completely eliminated and accordingly converted to Er-A, and the Er titer was improved by around 25% in the recombinant strain ZL1004 (genotype
PermK*-K-K-G
+
PermE*-K
+
PermA*-G
) and ZL1007 (genotype
PermK*-K-G-K
+
PermE*-K
+
PermA*-G
). This study may contribute to the continuous efforts toward further evaluation of the Er-producing system, with the aims of improving Er-A purity and production at the fermentation stage and lowering the production costs and environmental concerns in industry.
Bacillus thuringiensis
Cry1Ac Toxin-Binding and Pore-Forming Activity in Brush Border Membrane Vesicles Prepared from Anterior and Posterior Midgut Regions of Lepidopteran Larvae
Authors: Rodrigo-Simón Ana , Caccia Silvia , Ferré Juan
Published: January 2008

It is generally accepted that
Bacillus thuringiensis
Cry toxins insert into the apical membrane of the larval midgut after binding to specific receptors, and there is evidence that the distribution of binding molecules along the midgut is not uniform. By use of the voltage-sensitive dye DiSC
3
(5) and
125
I-labeled Cry1Ac, we have measured the effect of Cry1Ac in terms of permeabilization capacity and of binding parameters on brush border membrane vesicles (BBMV) prepared from the anterior and the posterior regions of the larval midgut from two insect species,
Manduca sexta
and
Helicoverpa armigera
. The permeabilizing activity was significantly higher with BBMV from the posterior region than with the one observed in the anterior region in both insect species. Instead,
125
I-Cry1Ac bound specifically to BBMV from the two midgut regions, with no significant differences in the binding parameters between the anterior and posterior regions within an insect species.
N
-acetylgalactosamine inhibition patterns on pore formation and binding differed between anterior and posterior midgut regions and between species, providing evidence of a multifaceted involvement of the sugar in the Cry1Ac mode of action. The analysis of binding and pore formation in different midgut regions could be an effective method to study differences in the mode of action of Cry1Ac toxin in different species.
Eighty Years after Its Discovery, Fleming's
Penicillium
Strain Discloses the Secret of Its Sex
Authors: Hoff Birgit , Pöggeler Stefanie , Kück Ulrich
Published: January 2008

Eighty years ago, Alexander Fleming discovered antibacterial activity in the asexual mold
Penicillium
, and the strain he studied later was replaced by an overproducing isolate still used for penicillin production today. Using a heterologous PCR approach, we show that these strains are of opposite mating types and that both have retained transcriptionally expressed pheromone and pheromone receptor genes required for sexual reproduction. This discovery extends options for industrial strain improvement programs using conventional genetical approaches.
Genetic Diversity of Heat-Labile Toxin Expressed by Enterotoxigenic
Escherichia coli
Strains Isolated from Humans
Authors: Lasaro M. A. , Rodrigues J. F. , Mathias-Santos C. , Guth B. E. C. , Balan A. , Sbrogio-Almeida M. E. , Ferreira L. C. S.
Published: January 2008

The natural diversity of the
elt
operons, encoding the heat-labile toxin LT-I (LT), carried by enterotoxigenic
Escherichia coli
(ETEC) strains isolated from humans was investigated. For many years, LT was supposed to be represented by a rather conserved toxin, and one derivative, produced by the reference H10407 strain, was intensively studied either as a virulence factor or as a vaccine adjuvant. Amplicons encompassing the two LT-encoding genes (
eltA
and
eltB
) of 51 human-derived ETEC strains, either LT
+
(25 strains) only or LT
+
/ST
+
(26 strains), isolated from asymptomatic (24 strains) or diarrheic (27 strains) subjects, were subjected to restriction fragment length polymorphism (RFLP) analysis and DNA sequencing. Seven polymorphic RFLP types of the H10407 strain were detected with six (BsaI, DdeI, HhaI, HincII, HphI, and MspI) restriction enzymes. Additionally, the single-nucleotide polymorphic analysis revealed 50 base changes in the
elt
operon, including 21 polymorphic sites at
eltA
and 9 at
eltB
. Based on the deduced amino acid sequences, 16 LT types were identified, including LT1, expressed by the H10407 strain and 23 other strains belonging to seven different serotypes, and LT2, expressed by 11 strains of six different serotypes. In vitro experiments carried out with purified toxins indicated that no significant differences in GM1-binding affinity could be detected among LT1, LT2, and LT4. However, LT4, but not other toxin types, showed reduced toxic activities measured either in vitro with cultured cells (Y-1 cells) or in vivo in rabbit ligated ileal loops. Collectively, these results indicate that the natural diversity of LTs produced by wild-type ETEC strains isolated from human hosts is considerably larger than previously assumed and may impact the pathogeneses of the strains and the epidemiology of the disease.
Regulation of Swarming Motility andflhDCSmExpression by RssAB Signaling inSerratia marcescens
Authors: Soo Po-Chi , Horng Yu-Tze , Wei Jun-Rong , Shu Jwu-Ching , Lu Chia-Chen , Lai Hsin-Chih
Published: January 2008

Serratia marcescenscells swarm at 30°C but not at 37°C, and the underlying mechanism is not characterized. Our previous studies had shown that a temperature upshift from 30 to 37°C reduced the expression levels offlhDCSmandhagSminS. marcescensCH-1. Mutation inrssAorrssB, cognate genes that comprise a two-component system, also resulted in precocious swarming phenotypes at 37°C. To further characterize the underlying mechanism, in the present study, we report that expression offlhDCSmand synthesis of flagella are significantly increased in therssAmutant strain at 37°C. Primer extension analysis for determination of the transcriptional start site(s) offlhDCSmrevealed two transcriptional start sites, P1 and P2, inS. marcescensCH-1. Characterization of the phosphorylated RssB (RssB∼P) binding site by an electrophoretic mobility shift assay showed direct interaction of RssB∼P, but not unphosphorylated RssB [RssB(D51E)], with the P2 promoter region. A DNase I footprinting assay using a capillary electrophoresis approach further determined that the RssB∼P binding site is located between base pair positions −341 and −364 from the translation start codon ATG in theflhDCSmpromoter region. The binding site overlaps with the P2 “−35” promoter region. A modified chromatin immunoprecipitation assay was subsequently performed to confirm that RssB∼P binds to theflhDCSmpromoter region in vivo. In conclusion, our results indicated that activated RssA-RssB signaling directly inhibitsflhDCSmpromoter activity at 37°C. This inhibitory effect was comparatively alleviated at 30°C. This finding might explain, at least in part, the phenomenon of inhibition ofS. marcescensswarming at 37°C.
A ViableBacillus subtilisStrain without Functional Extracytoplasmic Function Sigma Genes
Authors: Asai Kei , Ishiwata Keisuke , Matsuzaki Kunihiko , Sadaie Yoshito
Published: January 2008

We constructed aBacillus subtilisMarburg strain that harbors deletion mutations in all seven extracytoplasmic function (ECF) sigma genes. The strain shows wild-type growth at 37°C both in a complex and in a synthetic medium and exhibits wild-type sporulation. ECF sigma genes ofB. subtilisare dispensable as long as no stress is imposed, although they seem to be required for quick response to stresses.
Escherichia coli
Peptidase A, B, or N Can Process Translation Inhibitor Microcin C
Authors: Kazakov Teymur , Vondenhoff Gaston H. , Datsenko Kirill A. , Novikova Maria , Metlitskaya Anastasia , Wanner Barry L. , Severinov Konstantin
Published: January 2008

The heptapeptide-nucleotide microcin C (McC) targets aspartyl-tRNA synthetase. Upon its entry into a susceptible cell, McC is processed to release a nonhydrolyzable aspartyl-adenylate that inhibits aspartyl-tRNA synthetase, leading to the cessation of translation and cell growth. Here, we surveyed
Escherichia coli
cells with singly, doubly, and triply disrupted broad-specificity peptidase genes to show that any of three nonspecific oligopeptidases (PepA, PepB, or PepN) can effectively process McC. We also show that the rate-limiting step of McC processing in vitro is deformylation of the first methionine residue of McC.
New Hydrophobicity Constants of Substituents in Pyrazine Rings Derived from RP-HPLC Study
Authors: Kučerová-Chlupáčová Marta , Opletalová Veronika , Jampílek Josef , Doležel Jan , Dohnal Jiří , Pour Milan , Kuneš Jiří , Voříšek Viktor
Published: January 2008

Pyrazine derivatives show a wide range of biological activities. 1-Pyrazin-2-ylethan-1-ones have served as food flavourants, and together with pyrazine-2-carbonitriles have been widely used as intermediates in the synthesis of various heterocyclic compounds. In our laboratory, substituted pyrazine-2-carbonitriles and 1-pyrazin-2-ylethan-1-ones have been used as intermediates for the preparation of potential antifungal and antimycobacterial drugs. Using established methods, a library of pyrazine derivatives was synthesized. Homolytic alkylation of commercially available pyrazine-2-carbonitrile yielded a series of 5-alkylpyrazine-2-carbonitriles which were converted into the corresponding 1-(5-alkylpyrazin-2-yl)ethan-1-ones (5-alkyl-2-acetylpyrazines) via the Grignard reaction. Homolytic acetylation of pyrazine-2-carbonitrile yielded 5-acetylpyrazine-2-carbonitrile. Using the same procedure, 3-acetyl-5-tert-butylpyrazine-2-carbonitrile was obtained with 5-tert-butylpyrazine-2-carbonitrile as a starting material. The hydrophobicity of the compounds was determined both experimentally (RP-HPLC) and by computation (CS ChemOffice Ultra version 9.0, ACD/LogP version 1.0 and ACD/LogP version 9.04), and both the approaches were compared. New hydrophobicity constants π based on experimental results were derived. These constants are markedly different from tabulated constants π valid for benzene rings, and can be widely used in estimating physicochemical properties of new biologically active pyrazines.
Electrochemical Preparation of Alkynedial Tetramethyl Acetals
Authors: Hlavatý Jaromír , Polášek Miroslav
Published: January 2008

Tetramethyl acetals of alkynedials were prepared by anodic oxidation of corresponding alkyne-1,ω-diols (C4 and C6) in trimethyl orthoformate on glassy carbone anode in 80% yield. 1,1,4,4-Tetramethoxybut-2-yne (2a) can be prepared by this one-step procedure from but-2-yne-1,4-diol (1a) instead of a multistep chemical procedure starting from 2,5-dimethoxyfuran. Propargyl alcohol (3) can be similarly anodically oxidized in trimethyl orthoformate giving dimethyl acetal of propynal (4) in 85% yield.
Interpolation methods for geochemical maps: a comparative study using arsenic data from European stream waters
Authors: Lima A. , Plant J.A. , De Vivo B. , Tarvainen T. , Albanese S. , Cicchella D.
Published: January 2008

A geochemical map of As in water from the
FOREGS
Geochemical Atlas of Europe
, performed using the Alkemia interpolation method based on moving weighted median (MWM), and a comparable map prepared by kriging are compared with an As map prepared with a new multifractal inverse distance weighted (MIDW) interpolation method using GeoDas™ software. The colour scale classification of the MIDW interpolated map of As is based on the concentration–area (C-A) fractal method which allows images to be subdivided into components representing specific features on the ground related, for example, to geology.

Conventional techniques, such as MWM and kriging, are shown to smooth out the local variability of the geochemical data. The problem is most serious in maps prepared by kriging which erroneously show large areas of Europe to have high levels of As in water. On the other hand, MIDW creates a geochemical map in which information about the local data structure is retained. This is essential in distinguishing anomalies from background values. The information provided by background and anomaly maps, using the MIDW and fractal filtering methods, are shown to give more reliable upper limits of background values.
The rare earth element distribution over Europe: geogenic and anthropogenic sources
Authors: Fedele L. , Plant J.A. , De Vivo B. , Lima A.
Published: January 2008

The distribution of rare earth elements (REE) in Europe has been investigated using new geochemical data prepared by the Forum of European Geological Surveys (FOREGS), to estimate baseline values and to identify anomalous levels attributable to anthropogenic sources. Interpolated maps showing REE distributions in subsoils were generated using ArcView™ and classified with the new concentration–area (CA) fractal method available in the software GeoDAS™; they identify three broad ranges for baseline REE levels that are related to regional geological/geomorphological features. A combination of REE spider diagrams and interpolated maps showing REE distributions in floodplain and stream sediments was used to investigate anthropogenic sources of REE in Europe. It is concluded that the large-scale distribution patterns of REE over Europe are entirely attributable to geology. No evidence has been found of REE contamination from likely anthropogenic sources such as the electronics or nuclear industry. Three component colour maps of REE ratios (Gd/Lu, Eu/Eu* and La/Y) were used to identify the major plates of the Variscan orogeny and Variscan granites caught up in Alpine nappes in Italy.
Mineral sources and transport pathways for arsenic release in a coastal watershed, USA
Authors: Foley N.K. , Ayuso R.A.
Published: January 2008

Metasedimentary bedrock of coastal Maine contains a diverse suite of As-bearing minerals that act as significant sources of elements found in ground and surface waters in the region. Arsenic sources in the Penobscot Formation include, in order of decreasing As content by weight: löllingite and realgar (
c.
70%), arsenopyrite, cobaltite, glaucodot, and gersdorffite (in the range of 34–45%), arsenian pyrite (<4%), and pyrrhotite (<0.15%). In the Penobscot Formation, the relative stability of primary As-bearing minerals follows a pattern where the most commonly observed highly altered minerals are pyrrhotite, realgar, niccolite, löllingite > glaucodot, arsenopyrite-cobaltian > arsenopyrite, cobaltite, gersdorffite, fine-grained pyrite, Ni-pyrite > coarse-grained pyrite. Reactions illustrate that oxidation of Fe-As disulphide group and As-sulphide minerals is the primary release process for As. Liberation of As by carbonation of realgar and orpiment in contact with high-pH groundwaters may contribute locally to elevated contents of As in groundwater, especially where As is decoupled from Fe. Released metals are sequestered in secondary minerals by sorption or by incorporation in crystal structures. Secondary minerals acting as intermediate As reservoirs include claudetite (
c.
75%), orpiment (61%), scorodite (
c.
45%), secondary arsenopyrite (
c.
46%), goethite (<4490 ppm), natrojarosite (<42 ppm), rosenite, melanterite, ferrihydrite, and Mn-hydroxide coatings. Some soils also contain Fe-Co-Ni-arsenate, Ca-arsenate, and carbonate minerals. Reductive dissolution of Fe-oxide minerals may govern the ultimate release of iron and arsenic – especially As(V) – to groundwater; however, dissolution of claudetite (arsenic trioxide) may directly contribute As(III). Processes thought to explain the release of As from minerals in bedrock include oxidation of arsenian pyrite or arsenopyrite, or carbonation of As-sulphides, and most models based on these generally rely on discrete minerals or on a fairly limited series of minerals. In contrast, in the Penobscot Formation and other metasedimentary rocks of coastal Maine, oxidation of As-bearing Fe-cobalt-nickel-sulphide minerals, dissolution (by reduction) of As-bearing secondary As and Fe hydroxide and sulphate minerals, carbonation and/or oxidation of As-sulphide minerals, and desorption of As from Fe-hydroxide mineral surfaces are all thought to be involved. All of these processes contribute to the occurrence of As in groundwaters in coastal Maine, as a result of variability in composition and in stability of the As source minerals. Arsenic contents of soils and groundwater thus reflect the predominant influence and integration of a spectrum of primary mineral reservoirs (instead of single or unique mineral reservoirs). Cycling of As through metasedimentary bedrock aquifers may therefore depend on consecutive stages of carbonation, oxidation and reductive dissolution of primary and secondary As host minerals.
Physical determinants of left ventricular isovolumic pressure decline: model prediction with in vivo validation
Authors: Chung Charles S. , Kovács Sándor J.
Published: January 2008

The rapid decline in pressure during isovolumic relaxation (IVR) is traditionally fit algebraically via two empiric indexes: τ, the time constant of IVR, or τL, a logistic time constant. Although these indexes are used for in vivo diastolic function characterization of the same physiological process, their characterization of IVR in the pressure phase plane is strikingly different, and no smooth and continuous transformation between them exists. To avoid the parametric discontinuity between τ and τLand more fully characterize isovolumic relaxation in mechanistic terms, we modeled ventricular IVR kinematically, employing a traditional, lumped relaxation (resistive) and a novel elastic parameter. The model predicts IVR pressure as a function of time as the solution of d2P/d t2+ (1/μ)dP/d t + EkP = 0, where μ (ms) is a relaxation rate (resistance) similar to τ or τLand Ek(1/s2) is an elastic (stiffness) parameter (per unit mass). Validation involved analysis of 310 beats (10 consecutive beats for 31 subjects). This model fit the IVR data as well as or better than τ or τLin all cases (average root mean squared error for dP/d t vs. t: 29 mmHg/s for model and 35 and 65 mmHg/s for τ and τL, respectively). The solution naturally encompasses τ and τLas parametric limits, and good correlation between τ and 1/μ Ek(τ = 1.15/μ Ek− 11.85; r2= 0.96) indicates that isovolumic pressure decline is determined jointly by elastic ( Ek) and resistive (1/μ) parameters. We conclude that pressure decline during IVR is incompletely characterized by resistance (i.e., τ and τL) alone but is determined jointly by elastic ( Ek) and resistive (1/μ) mechanisms.
Protective effects of elevated endogenous surfactant pools to injurious mechanical ventilation
Authors: Yamashita Cory , Forbes Amy , Tessolini Jenna M. , Yao Li-Juan , Lewis James F. , Veldhuizen Ruud A. W.
Published: January 2008

Depletion of alveolar macrophages (AM) leads to an increase in endogenous surfactant that lasts several days beyond the repletion of AM. Furthermore, impairment to the endogenous pulmonary surfactant system contributes to ventilation-induced lung injury. The objective of the current study was to determine whether increased endogenous surfactant pools induced via AM depletion was protective against ventilation-induced lung injury. Adult rats were intratracheally instilled with either control or dichloromethylene diphosphonic acid (DMDP) containing liposomes to deplete AMs and thereby increase endogenous surfactant pools. Either 3 or 7 days following instillation, rats were exposed to 2 h of injurious ventilation using either an ex vivo or in vivo ventilation protocol and were compared with nonventilated controls. The measured outcomes were oxygenation, lung compliance, lavage protein, and inflammatory cytokine concentrations. Compared with controls, the DMDP-treated animals had significantly reduced AM numbers and increased surfactant pools 3 days after instillation. Seven days after instillation, AM numbers had returned to normal, but surfactant pools were still elevated. DMDP-treated animals at both time points exhibited protection against ventilation-induced lung injury, which included superior physiological parameters, lower protein leakage, and lower inflammatory mediator release into the air space, compared with animals not receiving DMDP. It is concluded that DMDP-liposome administration protects against ventilation-induced lung injury. This effect appears to be due to the presence of elevated endogenous surfactant pools.
Cointegration and Causality between Tourism and Poverty Reduction
Authors: Croes Robertico , Vanegas Manuel
Published: January 2008

This study, using cointegration and causality tests, investigates the relationship among tourism development, economic expansion, and poverty reduction in Nicaragua. The results indicate a long-run stable relationship among the three. The causality tests suggest a one-way Granger causal relation between tourism development and economic expansion, and between tourism and poverty reduction, and a bidirectional causal relation between economic expansion and poverty. The nexus of tourism, economic expansion, and poverty reduction is established in the Nicaraguan economy. This result is supported by testing the sensitivity of the Granger causality test under different lag selections along the optimal lag. The empirical evidence points to the potential economic muscle of tourism to seriously tackle Nicaraguan poverty at scale through helping both Nicaragua's public and private sectors allocate resources to tourism development, resulting in the overall improvement of the economy.
Prevalence of Platelet Nonresponsiveness to Aspirin in Patients Treated for Secondary Stroke Prophylaxis and in Patients With Recurrent Ischemic Events
Authors: Gengo Franci M. , Rainka Michelle , Robson Matthew , Gengo Michael F. , Forrest Alan , Hourihane Maurice , Bates Vernice
Published: January 2008

To determine the prevalence of platelet nonresponsiveness to aspirin treatment for secondary stroke prophylaxis, the authors studied consecutive patients during a 29–month period. Information regarding their ischemic events, risk factors, and medications was collected. Platelet aggregation in response to collagen and arachidonic acid was used to determine platelet responsiveness to aspirin. A total of 653 patients were evaluated. Of these, 129 patients (20%) were determined to be nonresponsive to aspirin based on continued platelet aggregation in response to collagen, arachidonic acid, or both. A total of 87 (13%) of the 653 patients were clinical aspirin failures (ie, presented with new focal cerebral ischemic symptoms while taking aspirin). Of the patients with new cerebral ischemic symptoms, 57 (66%) were determined to be platelet nonresponsive to aspirin. The odds ratio for platelet nonresponsiveness to aspirin in patients who suffered a recurrent ischemic event while taking aspirin was 14.25 (95% confidence interval: 8.5–23.7; P < .5). Continued platelet aggregation despite aspirin treatment occurred in 20% of ambulatory patients treated for secondary stroke prophylaxis. The prevalence of nonresponsiveness to aspirin was statistically higher in those patients who suffered recurrent cerebral ischemia while taking aspirin (P < .5) compared with patients who remained without new ischemic symptoms.
Authentic Leadership: Development and Validation of a Theory-Based Measure†
Authors: Walumbwa Fred O. , Avolio Bruce J. , Gardner William L. , Wernsing Tara S. , Peterson Suzanne J.
Published: January 2008

This study developed and tested a theory-based measure of authentic leadership using five separate samples obtained from China, Kenya, and the United States. Confirmatory factor analyses supported a higher order, multidimensional model of the authentic leadership construct (the Authentic Leadership Questionnaire [ALQ]) comprising leader self-awareness, relational transparency, internalized moral perspective, and balanced processing. Structural equation modeling (SEM) demonstrated the predictive validity for the ALQ measure for important work-related attitudes and behaviors, beyond what ethical and transformational leadership offered. Finally, results revealed a positive relationship between authentic leadership and supervisor-rated performance. Implications for research and practice are discussed.
Us and Me: Team Identification and Individual Differentiation as Complementary Drivers of Team Members' Citizenship and Creative Behaviors
Authors: Janssen Onne , Xu Huang
Published: January 2008

The authors investigate team identification and individual differentiation as complementary drivers of team members'citizenship and creative behavior. As hypothesized, the results of a survey among 157 middle-management team members show team identification to be positively related to citizenship behavior toward other team members, whereas individual differentiation is positively associated with creative behavior. Moreover, citizenship behavior is found to be a mediator that linked team identification to an individual's effectiveness as a team member, whereas creative behavior is the mediating link in the relationship between individual differentiation and individual effectiveness. Theoretical implications and suggestions for practitioners are discussed.
Tightening Income Documentation in a Means-Tested Program
Authors: Gleason Philip , Burghardt John , Strasberg Paul , Hulsey Lara
Published: January 2008

Programs using means tests to identify low-income households face a trade-off between promoting access and ensuring program integrity. The authors use a comparison-district design to estimate the effects of a pilot program to improve the accuracy of the process of certifying students for free or reduced-price meals in the National School Lunch Program. This pilot program required households to provide income documentation with their applications for these benefits. Requiring income documentation did not reduce the proportion of ineligible households getting free or reduced-price meals. Furthermore, this requirement did reduce access to the program among eligible households.
The Impact of Child Obesity on Active Parental Consent in School-Based Survey Research on Healthy Eating and Physical Activity
Authors: Mellor Jennifer M. , Rapoport Ronald B. , Maliniak Daniel
Published: January 2008

Previous studies have shown that active consent procedures result in sampling bias in surveys dealing with adolescent risk behaviors such as cigarette smoking and illicit drug use. To examine sampling bias from active consent procedures when the survey topic pertains to childhood obesity and associated health behaviors, the authors pair data obtained from both active and passive consent procedures. The authors find that parents of children who are overweight or at risk for being overweight are significantly less likely to give active consent. In addition, parents of children enrolled in lower grades are more reluctant to consent to participate.
A Person-Centered Communication and Reflection Model: Sharing Decision-Making in Chronic Care
Authors: Zoffmann Vibeke , Harder Ingegerd , Kirkevold Marit
Published: January 2008

Shared decision making (SDM) is regarded as an ideal in chronic illness care but is difficult to implement in practice. Communication and reflection play an important role and need further investigation. Using grounded theory, we studied patient-provider interaction in a difficult and advanced area: managing poorly controlled diabetes. A person-centered communication and reflection model was developed, identifying SDM in chronic care to be a question of professionals gaining insight into patients' decisions, rather than the opposite. The model reveals important choices in communication and reflection, which were decisive for whether SDM was achieved or not. SDM involved co-creating person-centered knowledge: concrete evidence which empowered patients and professionals in problem solving. Although further testing is required, the general tenets of the model are expected to be applicable across chronic conditions. Findings indicate that SDM in chronic illness care requires innovation in current approaches to decision making and problem solving.
Precarious Listening
Authors: Linnell Sheridan , Bansel Peter , Ellwood Constance , Gannon Susanne
Published: January 2008

This article attempts to hold thought open in a textual space that often forecloses thought. The authors present arguments but work them through poetry, memoir, pictures, and exposition. They frame this work in particular as an improvisation around—and intervention into—more familiar practices of collective biography, narrative, and art therapies and situate it as a new pedagogy for collective academic practice. The article emerged from a project in which the authors produced an aesthetic practice and attempted an ethics of listening while recognizing that academic experiences more often venerate speech. The authors write a collective text but sit apart within it as well as together, thus emphasizing singularity and collectivity, locatedness and the body. They take their work and themselves within that work as precarious, tentative, and uncertain and are concerned to ask questions that might keep thought open rather than provide answers.
Size effect on strength of alumina agglomerates
Authors: Wu D. F. , Zhou J. C. , Li Y. D.
Published: January 2008

The size effect on strength of alumina agglomerates was examined, and the applicability of the often used size effect laws was discussed. It is concluded that there is a significant energetic size effect, which shows that the Weibull statistical size effect does not apply. However, the size effect on the tensile strength of the agglomerates examined can be addressed well by the energetic–statistical size effect law.
Continuous separation of Fe–Al–Zn dross phase from hot dip galvanised melt using alternating magnetic field
Authors: Dong A. P. , Shu D. , Wang J. , Cai X. C. , Sun B. D. , Cui J. , Shen J. G. , Ren Y. S. , Yin X. D.
Published: January 2008

Experiments to continuously separate Fe–Al–Zn dross phase from hot dip galvanising zinc melt were conducted on a laboratory scale apparatus by using high frequency alternating magnetic field. Effects of processing time ( t) on separation efficiency were investigated. The experimental results show that using the electromagnetic repulsive force resulting from the electrical conductivity difference between zinc melt and Fe–Al–Zn dross phase, the deleterious zinc dross particles causing surface defects of galvanising steel sheets can be continuously separated from the zinc bath under alternating magnetic field, and the separation efficiency increases with the increase in processing time. When the magnetic frequency is 17·5 kHz, the effective magnetic flux intensity is 0·1 T, the cross-section of the ceramic square pipe is 10 × 10 mm, and the processing time is 0·6–2·5 s, the separation efficiency of zinc dross varies from 43·76 to 85·71%, and the experimental results are in reasonable agreement with the theoretical results.
Soft magnetic properties and microstructure of novel Nb poor Finemet type alloys
Authors: Liu H. S. , Yin C. H. , Miao X. X. , Han Z. D. , Wang D. H. , Du Y. W.
Published: January 2008

Series of Nb poor Finemet type alloys were fabricated by substitution of Nb by Al for the first time, and soft magnetic properties of them have been researched by using permeability spectroscopy and X-ray diffraction. It is found that with 0·5 at.-% substitution of Nb by Al, the initial permeability is improved drastically, and the relaxation frequency is enhanced as well, and the loss factor reduces to a very low value of the order of 10−6 in the low frequency range compared to conventional Finemet. The improved soft magnetic properties are related to the lower crystalline anisotropy of FeSiAl compared to FeSi and the proper crystalline volume fraction. This research shows that the substitution of Nb by Al in Nb poor Finemet type alloys can bear ultrasoft magnetic properties at less cost.
Characteristics of multilayer laser cladding using powder mixture of Co based alloy and vanadium carbide
Authors: Xu G. J. , Kutsuna M.
Published: January 2008

The powder mixture of Co based alloy (Stellite 6) and vanadium carbide (VC) in the range of 0–56 wt-%VC fraction with a constant chemical composition multilayer cladding (CCCMLC) and functionally gradient material multilayer cladding (FGMMLC) were deposited on stainless steel (SUS304) by a 2·4 kW CW CO2 laser and powder feeder. In the CCCMLC, the VC weight fractions at each layer are constant. In the FGMMLC, the VC weight fractions at each layer are varied by controlling the disc rotation speed of the powder feeder. To decrease crack sensitivity of the clad layer, influence of preheating temperature and VC weight fraction using the CCCMLC and FGMMLC on the crack sensitivity was investigated comparatively. As a result, in the FGMMLC with gradual increase in VC particles, clad at three subsequent layers shifts the critical amount of VC at which cracking appears to be the highest level, or it reduces the required preheating temperature, namely, the crack sensitivity of the clad layer using FGMMLC is lower than that using CCCMLC. On the other hand, the microstructure, Vickers hardness and wear resistance of the clad layer were investigated by an X-ray diffractometer, energy dispersion spectroscopy (EDS), scanning electron microscope (SEM), laser microscope, wear tester and hardness tester. Microstructures of the clad layer were classified into two types, hypoeutectic structure and hypereutectic structure. The wear resistance of clad layer made by CCCMLC and FGMMLC has been almost the same.
B7-H1 is a ubiquitous antiapoptotic receptor on cancer cells
Authors: Azuma Takeshi , Yao Sheng , Zhu Gefeng , Flies Andrew S. , Flies Sarah J. , Chen Lieping
Published: January 2008

B7-H1 is an immunoglobulin-like immune suppressive molecule broadly detectable on the majority of human and rodent cancers, and its functions have been attributed to delivering an inhibitory signal to its counter-receptor programmed death-1 (PD-1) on T cells. Here we report that B7-H1 on cancer cells receives a signal from PD-1 to rapidly induce resistance against T cell–mediated killing because crippling signaling capacity of B7-H1 but not PD-1 ablates this resistance. Importantly, loss of B7-H1 signaling is accompanied by increased susceptibility to immune-mediated tumoricidal activity. In addition to resistance against T-cell destruction, B7-H1+ cancer cells also become refractory to apoptosis induced by Fas ligation or the protein kinase inhibitor Staurosporine. Our study reveals a new mechanism by which cancer cells use a receptor on immune cells as a ligand to induce resistance to therapy.
CD8+ but not CD4+ T cells require cognate interactions with target tissues to mediate GVHD across only minor H antigens, whereas both CD4+ and CD8+ T cells require direct leukemic contact to mediate GVL
Authors: Matte-Martone Catherine , Liu Jinli , Jain Dhanpat , McNiff Jennifer , Shlomchik Warren D.
Published: January 2008

Whether T-cell antigen receptors (TCR) on donor T cells require direct interactions with major histocompatibility complex class I or class II (MHCI/MHCII) molecules on target cells to mediate graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) is a fundamental question in allogeneic stem-cell transplantation (alloSCT). In MHC-mismatched mouse models, these contacts were not required for GVHD. However, this conclusion may not apply to MHC-matched, multiple minor histocompatibility antigen-mismatched alloSCT, the most common type performed clinically. To address this, we used wild-type (wt)→MHCI−/− or wt→MHCII−/− bone marrow chimeras as recipients in GVHD experiments. For GVL experiments, we used MHCI−/− or MHCII−/− chronic-phase CML cells created by expressing the BCR-ABL cDNA in bone marrow from MHCI−/− or MHCII−/− mice. TCR/MHCI contact was obligatory for both CD8-mediated GVHD and GVL. In contrast, CD4 cells induced GVHD in wt→MHCII−/− chimeras, whereas MHCII−/− mCP-CML was GVL-resistant. Donor CD4 cells infiltrated affected skin and bowel in wt→MHCII−/− recipients, indicating that they mediated GVHD by acting locally. Thus, CD4 cells use distinct effector mechanisms in GVHD and GVL: direct cytolytic action is required for GVL but not for GVHD. If these noncytolytic pathways can be inhibited, then GVHD might be ameliorated while preserving GVL.
Should adjustment for covariates be used in prevalence estimations?
Authors: Li Wenjun , Stanek Edward J , Bertone-Johnson Elizabeth R
Published: January 2008

Background

Adjustment for covariates (also called auxiliary variables in survey sampling literature) is commonly applied in health surveys to reduce the variances of the prevalence estimators. In theory, adjusted prevalence estimators are more accurate when variance components are known. In practice, variance components needed to achieve the adjustment are unknown and their sample estimators are used instead. The uncertainty introduced by estimating variance components may overshadow the reduction in the variance of the prevalence estimators due to adjustment. We present empirical guidelines indicating when adjusted prevalence estimators should be considered, using gender adjusted and unadjusted smoking prevalence as an illustration.

Methods

We compare the accuracy of adjusted and unadjusted prevalence estimators via simulation. We simulate simple random samples from hypothetical populations with the proportion of males ranging from 30% to 70%, the smoking prevalence ranging from 15% to 35%, and the ratio of male to female smoking prevalence ranging from 1 to 4. The ranges of gender proportions and smoking prevalences reflect the conditions in 1999–2003 Behavioral Risk Factors Surveillance System (BRFSS) data for Massachusetts. From each population, 10,000 samples are selected and the ratios of the variance of the adjusted prevalence estimators to the variance of the unadjusted (crude) ones are computed and plotted against the proportion of males by population prevalence, as well as by population and sample sizes. The prevalence ratio thresholds, above which adjusted prevalence estimators have smaller variances, are determined graphically.

Results

In many practical settings, gender adjustment results in less accuracy. Whether or not there is better accuracy with adjustment depends on sample sizes, gender proportions and ratios between male and female prevalences. In populations with equal number of males and females and smoking prevalence of 20%, the adjusted prevalence estimators are more accurate when the ratios of male to female prevalences are above 2.4, 1.8, 1.6, 1.4 and 1.3 for sample sizes of 25, 50, 100, 150 and 200, respectively.

Conclusion

Adjustment for covariates will not result in more accurate prevalence estimator when ratio of male to female prevalences is close to one, sample size is small and risk factor prevalence is low. For example, when reporting smoking prevalence based on simple random sampling, gender adjustment is recommended only when sample size is greater than 200.
The Asymmetrical Influence of Sex Dissimilarity in Distributive vs. Colocated Work Groups
Authors: Chattopadhyay Prithviraj , George Elizabeth , Shulman Arthur D.
Published: January 2008

Data from 101 Australian research scientists were used to examine the relationship between sex dissimilarity and work group identification, and task and emotional conflict. Based on social identity and self-categorization theories, these relationships were argued to vary between men and women, and between colocated and distributive work groups. Women reported lower levels of work group identification and higher levels of task and emotional conflict in conjunction with higher levels of sex dissimilarity. Men reported lower levels of task conflict in conjunction with higher levels of sex dissimilarity. No parallel effects on identification or emotional conflict were observed. Sex dissimilarity was found to have a stronger influence on work group identification, and task and emotional conflict in colocated work groups than in distributive work groups.
Guiding local sedation services in dentistry
Authors: Worker Charlotte
Published: January 2008

Over the past three years, the Faculty of General Dental Practice (UK) and the Department of Health (DH) have worked together to develop a series of competency frameworks for dentists with special interests (DwSIs). The frameworks are intended for use by dentists and primary care trusts (PCTs) and set out competencies for the scope of treatment that can be undertaken by dentists who have developed special interests. By the end of 2007, frameworks had been published in minor oral surgery, orthodontics, periodontics, endodontics and prison dentistry.
Surgical training in France
Authors: Tiret Emmanuel
Published: January 2008

In France, medical students spend six years at university. At the end of the first year of study a rigorous selection process is conducted, resulting in only 15% of the students proceeding to the subsequent years. The final medical examination, the examen classant national, a standardised national exam, is taken at the end of the sixth year. It is a written exam, involving the discussion of nine clinical cases.
College to feature in flagship science documentary
Authors: Worrall Matt
Published: January 2008

The College is to feature in a documentary being produced for the latest series of BBC science programme, Horizon, focusing on the medical use of cadavers. The programme looks at the growth in the use of human tissue in training and surgery, and explores the practicalities involved in the supply of bodies. The film will feature footage of a course in our new Wolfson surgical skills centre and an interview with Dick Rainsbury, director of education, explaining why bodies are so important for surgical training.
The Solubility Constant of Variscite
Authors: Iuliano Mauro , Ciavatta Liberato , De Tommaso Gaetano
Published: January 2008

Only a few studies have been made on the ion product of variscite, Al(III) phosphate dihydrate, AlPO4·2H2O, a parameter of fundamental importance in clarifying the fixation of soluble phosphates in acid soils. The solubility of variscite in H3PO4 solutions of molality ranging from 1 × 10−4 to 0.1 mol kg−1 was determined at 25°C. The data were explained with a value of the ion product equal to 10−3.14 mol−1 kg (at the infinite dilution reference state) and assuming the formation of complexes AlPO4(aq), AlHPO4+, and Al(H2PO4)2+ The solubility product obtained in this work differs by orders of magnitude from the literature values. The discrepancies are mainly due to the use of solids of different composition as well as to the assumption of the Al3+ ion as the unique soluble Al species. On the basis of equilibrium constants, the fixation in acid soils of soluble phosphates implicates the formation of variscite, while only at higher concentrations does the fixation occur as strengite.
Characterization of Organo‐Mineral Aggregates of Chernozem in Northeast China and Their Adsorption Behavior to Phenanthrene
Authors: Huang Qing , Li Fasheng , Xiao Ru , Wang Qunhui , Tan Wenjie
Published: January 2008

Organo‐mineral aggregates in various fractions including clay, silt, fine sand, and coarse sand were isolated from a Chernozem in northeast China by ultrasonic dispersion in water followed by sedimentation. The physicochemical properties of different fractions were determined and the organo‐mineral aggregates were characterized jointly with Fourier‐transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), x‐ray diffraction (XRD), and cross‐polarization (CP) with magic‐angle spinning (MAS) 13C nuclear magnetic resonance (NMR) spectrometry. The XRD patterns showed that clay was dominated by quartz and calcite, while the mineral assemblage of silt was composed of quartz, calcite, plagioclase, and trace amounts of mica and chlorite. The results from FTIR spectra were consistent with those from XRD. The SEM images indicated that the particle surface became smoother with increasing particle size. The CP‐MAS 13C NMR spectra showed that the contents of aromatic C in clay, silt, fine sand, and coarse sand were 25.6, 28.19, 17.22, and 26.32%, respectively. The adsorption and desorption behaviors of polycyclic aromatic hydrocarbons on four soil fractions were investigated using phenanthrene as a model substrate. The adsorption and desorption isotherms for all the fractions were well described by the modified Freundlich equation, and batch experiments demonstrated that the adsorption capacity increased with decreasing particle size. The desorption capacities of phenanthrene on clay and silt were larger than that of sand. The organic C normalized adsorption coefficients were positively correlated with the contents of nonpolar and aromatic C. The adsorption mechanism may be that phenanthrene undergoes a π–π interaction with organic matter of aggregates and is adsorbed on the aggregates.