bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of rapid thermal annealing on the ordering of AlInP grown by metal-organic vapor-phase epitaxy
Authors: Tang Xiaohong , Zhao Jinghua , Chin Mee Koy , Mei Ting , Yin Zongyou , Deny Sentosa , Du An Yan
Published: October 2005

Spontaneous CuPt ordering is observed in AlxIn1−xP layers grown by metal-organic vapor-phase epitaxy in pure nitrogen ambient with tertiarybutylphosphine as phosphorus precursor. Changes of the degree of ordering of the AlxIn1−xP epilayer versus annealing temperature have been investigated by using photoluminescence and transmission electron diffraction. The degree of ordering of the AlxIn1−xP layers is reduced after annealing the sample at a temperature higher than the sample growth temperature. It becomes completely disordered when the annealing temperature reaches 900°C and above.
Leakage current and breakdown electric-field studies on ultrathin atomic-layer-deposited Al2O3 on GaAs
Authors: Lin H. C. , Ye P. D. , Wilk G. D.
Published: October 2005

Atomic-layer deposition (ALD) provides a unique opportunity to integrate high-quality gate dielectrics on III-V compound semiconductors. We report detailed leakage current and breakdown electric-field characteristics of ultrathin Al2O3 dielectrics on GaAs grown by ALD. The leakage current in ultrathin Al2O3 on GaAs is comparable to or even lower than that of state-of-the-art SiO2 on Si, not counting the high-k dielectric properties for Al2O3. A Fowler-Nordheim tunneling analysis on the GaAs∕Al2O3 barrier height is also presented. The breakdown electric field of Al2O3 is measured as high as 10MV∕cm as a bulk property. A significant enhancement on breakdown electric field up to 30MV∕cm is observed as the film thickness approaches to 1nm.
Probing the excited state distributions of CdTe∕ZnTe self-assembled quantum dots using resonant Raman scattering
Authors: Abdi A. , Hoang T. B. , Mackowski S. , Smith L. M. , Jackson H. E. , Yarrison-Rice J. M. , Kossut J. , Karczewski G.
Published: October 2005

Resonant Raman scattering is a sensitive means to probe electronic states in semiconductor materials even when such states are not accessible either through photoluminescence or transport techniques. We show that resonant Raman scattering can be used to probe the excited state distribution of CdTe∕ZnTe quantum dots at room temperature. In particular we apply this technique to study the changes of such quantum dots after rapid thermal annealing.
Role of Sb in the growth and optical properties of 1.55μm GaInN(Sb)As∕GaNAs quantum-well structures by molecular-beam epitaxy
Authors: Sun H. D. , Calvez S. , Dawson M. D. , Gupta J. A. , Sproule G. I. , Wu X. , Wasilewski Z. R.
Published: October 2005

High-quality GaInN(Sb)As∕GaNAs double quantum wells (QWs) which emit at 1.54μm wavelength at room temperature with a narrow linewidth of ∼34meV (12meV at 5K) were fabricated by molecular-beam epitaxy on GaAs substrates. Photoluminescence and photoluminescence excitation spectroscopy were used to study the electronic states and optical properties of these heterostructures. By characterizing samples grown using different fluxes of Sb, the role played by Sb in the growth process and optical properties was elucidated. At low Sb flux, Sb atoms act mainly as a surfactant which improves the microstructure of the QWs and enhances the photoluminescence intensity. With an increase of Sb flux, some of the Sb atoms may incorporate into GaInNAs to form a quinary compound. In the latter case, the incorporation of Sb could also enhance the N composition in the QWs, which may be responsible for the further reduction of the band gap.
Piezoelectric properties of Li- and Ta-modified (K0.5Na0.5)NbO3 ceramics
Authors: Hollenstein Evelyn , Davis Matthew , Damjanovic Dragan , Setter Nava
Published: October 2005

Lead-free, potassium sodium niobate piezoelectric ceramics substituted with lithium (K0.5−x∕2,Na0.5−x∕2,Lix)NbO3 or lithium and tantalum (K0.5−x∕2,Na0.5−x∕2,Lix)(Nb1−y,Tay)O3 have been synthesized by traditional solid state sintering. The compositions chosen are among those recently reported to show high piezoelectric properties [Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, T. Nagaya, and M. Nakamura, Nature (London) 42, 84 (2004); Y. Guo, K. Kakimoto, and H. Ohsato, Appl. Phys. Lett. 85, 4121 (2004); Mater. Lett. 59, 241 (2005)]. We show that high densities and piezoelectric properties can be obtained for all compositions by pressureless sintering in air, without cold isostatic pressing, and without any sintering aid or special powder treatment. Resonance and converse piezoelectric (strain-field) measurements show a thickness coupling coefficient kt of 53% and converse piezoelectric coefficient d33 around 200pm∕V for the Li-substituted ceramics, and a kt of 52% and d33 over 300pm∕V for the Li- and Ta-modified samples. The unipolar strain-field hysteresis is small and comparable to that measured under similar conditions in hard Pb(Zr,Ti)O3. A peak of piezoelectric properties can be noted close to the morphotropic phase boundary. These ceramics look very promising as possible, practicable, lead-free replacements for lead zirconate titanate.
Field-effect transistors with layer-by-layer self-assembled nanoparticle thin films as channel and gate dielectric
Authors: Cui Tianhong , Liu Yi , Zhu Mo
Published: October 2005

This letter reports the fabrication of inorganic field-effect transistors (FET) combing “bottom-up” layer-by-layer (LbL) nanoself-assembly and “top-down” micromanufacturing techniques. The self-assembled multilayer of In2O3 and SiO2 nanoparticles, patterned by photolithography and lift-off methods, serve as channels and insulating layers, respectively. This FET works at an accumulation mode, with a threshold voltage of −1.25V, a carrier mobility of 4.24×10−3cm2∕Vs, and an on/off current ratio of 102. Due to the simple, low-cost, and low-temperature features of the LbL nanoself-assembly technique that greatly eliminates expensive and complex facilities, this approach is particularly suitable for the very inexpensive FET fabrication.
Effects of hydrophobic surface on stability and transition
Authors: Min Taegee , Kim John
Published: October 2005

The effects of a hydrophobic surface on stability and transition in wall-bounded shear flows are investigated. The hydrophobic surface is represented by a slip-boundary condition on the surface. The linear stability analysis with slip-boundary conditions shows that the critical Reynolds number increases with streamwise slip. The effects of slip-boundary conditions on the transient growth of initial disturbances are investigated through the singular value decomposition (SVD) analysis of the linearized Navier–Stokes equations. The maximum transient growth (i.e., the amplification factor for the optimal disturbance) is reduced with streamwise slip, indicating that non-normality of the linearized Navier–Stokes equations is reduced with streamwise slip. Finally, it is shown that the transition to turbulence is delayed significantly with streamwise slip, whereas spanwise slip induces an earlier transition. The present results suggest that it is desirable to develop a hydrophobic surface with specified directional sensitivity in order to meet a particular need for specific applications.
Ecological responses to simulated benthic‐derived nutrient subsidies mediated by omnivorous fish
Authors: GLAHOLT STEPHEN P. , VANNI MICHAEL J.
Published: October 2005

1. Fish can play an important role in coupling benthic and pelagic habitats by consuming benthic prey and providing essential nutrients to algae in dissolved form. However, little is known about the factors affecting the magnitude of this nutrient subsidy.

2. Using laboratory and mesocosm experiments we evaluated how varying ingestion rates of bluegill sunfish (Lepomis macrochirus) affects fish excretion rates of both nitrogen (N) and phosphorus (P). During the 10‐week mesocosm experiment, we also evaluated how varying ingestion rates may affect plankton community dynamics, and nutrient flux between pelagic and benthic habitats. Lastly, bioenergetic/mass balance models were used to examine the nutrient stoichiometry of fish body composition and excretion products.

3. Under laboratory conditions, both N and P excretion rates increased with increased ingestion of benthic prey surrogates (earthworms). This effect was more pronounced for N than P. Furthermore, under the more realistic conditions of the mesocosm experiment ingestion rate had no significant effect on P excretion rate.

4. Increased fish ingestion rate in the mesocosm experiment increased total algal biomass and the flux of nutrients from the water column to sediments. Effects of variable ingestion were much stronger on periphyton biomass and algal sedimentation rates than on phytoplankton or zooplankton biomass or composition.

5. Fish body nutrient composition was greatly affected by ingestion rate. N content increased and P content decreased with ingestion rate. As a result, the N : P ratio of fish bodies also increased with ingestion rate. The N : P ratio of nutrients excreted by fish also increased with ingestion rate, counter to predictions of stoichiometric theory, which predicts that excreted N : P ratio is negatively correlated to body N : P. However, this finding can be explained by relaxing the assumption of constant nutrient assimilation rates, and our mass balance data suggest that assimilation rates vary indeed with ingestion rate.

6. Our study provides experimental evidence that translocation of benthic‐derived nutrients by fish can affect the flux of nutrients among habitats, while also suggesting that stoichiometry models need to better incorporate how variable ingestion rates affect nutrient assimilation and excretion rates.
Women's experiences of fatigue in chronic illness
Authors: Kralik Debbie , Telford Kerry , Price Kay , Koch Tina
Published: October 2005

Aim. The aim of this paper is to add a qualitative dimension to the body of knowledge about fatigue by revealing the meaning given by women living with chronic illness to the experience of fatigue.

Background. Fatigue is a common symptom experienced by people who live with chronic illness. It pervades every aspect of life and may be experienced in physical, psychological, emotional or social dimensions. Management of fatigue relies heavily on the individual's ability to employ self‐care actions. The invisibility of fatigue is recognized as one of the most frustrating aspects, which can lead to lack of understanding and misunderstanding by others.

Method. We report the findings of data from research in progress (2003–2005). Data were generated via email group conversations between us and 30 women who live with long‐term illness.

Findings. A recurring conversational thread has been women's experiences of fatigue when living with long‐term illness. Although fatigue has been reported to be a major obstacle to maintaining usual daily activities and quality of life, few studies have explored this common symptom from the perspective of people themselves. Common themes found in the experience of fatigue as described by women are the meaning of fatigue, awareness as self‐care, fatigue as invisible to others, seeking medical validation and accountability for self‐care.

Conclusion. It is vital for healthcare workers to give opportunities for women to talk about fatigue, validate their experiences and provide support with self‐care. Healthcare workers are encouraged to challenge their own meanings and expectations surrounding a person's report of fatigue so that opportunities for therapeutic intervention can be facilitated.
Preparing a large data set for analysis: using the Minimum Data Set to study perineal dermatitis
Authors: Savik Kay , Fan Qiao , Bliss Donna , Harms Susan
Published: October 2005

Aim.  The aim of this paper is to present a practical example of preparing a large set of Minimum Data Set records for analysis, operationalizing Minimum Data Set items that defined risk factors for perineal dermatitis, our outcome variable.

Background.  Research with nursing home elders remains a vital need as ‘baby boomers’ age. Conducting research in nursing homes is a daunting task. The Minimum Data Set is a standardized instrument used to assess many aspects of a nursing home resident's functional capability. United States Federal Regulations require a Minimum Data Set assessment of all nursing home residents. These large data would be a useful resource for research studies, but need to be extensively refined for use in most statistical analyses. Although fairly comprehensive, the Minimum Data Set does not provide direct measures of all clinical outcomes and variables of interest.

Method.  Perineal dermatitis is not directly measured in the Minimum Data Set. Additional information from prescribers’ (physician and nurse) orders was used to identify cases of perineal dermatitis. The following steps were followed to produce Minimum Data Set records appropriate for analysis: (1) identification of a subset of Minimum Data Set records specific to the research, (2) identification of perineal dermatitis cases from the prescribers’ orders, (3) merging of the perineal dermatitis cases with the Minimum Data Set data set, (4) identification of Minimum Data Set items used to operationalize the variables in our model of perineal dermatitis, (5) determination of the appropriate way to aggregate individual Minimum Data Set items into composite measures of the variables, (6) refinement of these composites using item analysis and (7) assessment of the distribution of the composite variables and need for transformations to use in statistical analysis.

Results.  Cases of perineal dermatitis were successfully identified and composites were created that operationalized a model of perineal dermatitis.

Conclusion.  Following these steps resulted in a data set where data analysis could be pursued with confidence. Incorporating other sources of data, such as prescribers’ orders, extends the usefulness of the Minimum Data Set for research use.
Ways of talking about experiences of pain among older patients following orthopaedic surgery
Authors: Bergh Ingrid , Jakobsson Eva , Sjöström Björn , Steen Bertil
Published: October 2005

Aim.  The aim of this study was to examine how older patients who had undergone hip surgery described their experience of pain.

Background.  A verbal report of pain is considered to be the single most reliable indicator of a person's pain experience. When assessing pain, healthcare professionals must be able to interpret the content of pain reports in order to understand older patient's pain experiences.

Methods.  The study was carried out in two orthopaedic and two elder care wards in a large university hospital in Sweden in 2000. Altogether, 38 patients with hip replacement (mean age = 75) and 22 patients with hip fracture (mean age = 81) took part. A face‐to‐face interview was conducted with each patient on the second day after operation. Data were transcribed and analysed using descriptive qualitative content analysis.

Findings.  Participants expressed their pain in a nuanced and detailed way in everyday language. Four main themes with sub‐themes emerged: (a) objectification (localizing; quantifying; characterizing; temporalizing); (b) compensating (substitution; picturing); (c) explaining (functionalizing pain and its relief; externalizing pain and its relief); (d) existentializing (present pain orientation; future pain orientation).

Conclusions.  Exploring the ways older patients talk about pain is expected to result in a better understanding of the older patient's need of empathic individualized care and in the optimization of pain management.
Effects of timed voiding for the management of urinary incontinence in adults: systematic review
Authors: Ostaszkiewicz Joan , Roe Brenda , Johnston Linda
Published: October 2005

Aim.  The aim of this paper is to present a systematic review assessing the effectiveness of timed voiding for the management of urinary incontinence in adults.

Background.  Despite the widespread use of systematic voiding programmes, their effectiveness is unclear, and the evidence for timed voiding has not been subject to rigorous and systematic evaluation. The impact on psychosocial factors and cost is also untested. The physiological basis for timed voiding is also poorly established.

Methods.  The systematic review incorporated the methodology of the Cochrane Collaboration. All randomized or quasi‐randomized controlled trials that addressed timed voiding for the management of urinary incontinence in adults were searched, appraised, analysed and summarized. The date of the latest search was 2002. Data were extracted independently and appraised according to the level of concealment of random allocation prior to formal entry; few and identifiable withdrawals and dropouts and an analysis based on an intention to treat. The relative risk for dichotomous data was calculated with 95% confidence intervals. Where data were insufficient to support quantitative analysis, a narrative overview was undertaken.

Results.  Two trials of timed voiding met the inclusion criteria. In both, timed voiding was combined with other strategies. Participants were predominantly cognitively and physically impaired older women who resided in nursing home settings. Within‐group improvements for the intervention groups were reported for both trials. One trial additionally reported a statistically significant reduction in night‐time incontinence for the intervention group. The quality of the trials was modest and interpretation was limited by the potential for bias associated with inadequate concealment, missing data and no analysis by intention to treat.

Conclusion.  Terms used to describe voiding programmes that involve a fixed interval of voiding are variable. No conclusions can be drawn at this point about the effectiveness of timed voiding for the management of urinary incontinence in adults.
Barriers to evidence‐based practice in primary care nursing – why viewing decision‐making as context is helpful
Authors: Thompson Carl , McCaughan Dorothy , Cullum Nicky , Sheldon Trevor , Raynor Pauline
Published: October 2005

Aim.  This paper reports a study examining the barriers associated with research knowledge transfer amongst primary care nurses in the context of clinical decision‐making.

Background.  The research literature on barriers to nurses’ use of research knowledge is characterized by studies that rely primarily on self‐report data, making them prone to reporting biases. Studies of the barriers to evidence‐based practice often fail to examine information use and behaviour in the context of clinical decision‐making.

Methods.  A multi‐site, mixed method, case study was carried out in 2001. Data were collected in three primary care organizations by means of interviews with 82 primary care nurses, 270 hours of non‐participant observation and 122 Q‐sorts. Nurses were selected using a published theoretical sampling frame. Between‐methods triangulation was employed and data analysed according to the principles of constant comparison. Multiple linear regression was used to explore relationships between a number of independent demographic variables (such as length of clinical experience) and the dependent variable of nurses’ perspectives on the barriers to their use of research knowledge.

Results.  Three perspectives on barriers to research information use emerged: the need to bridge the skills and knowledge gap for successful knowledge transfer; information formats need to maximize limited opportunities for consumption; and limited access in the context of limited time for decision‐making and information consumption. Demographic variables largely failed to predict allegiance to any of the perspectives identified.

Conclusions.  Researchers should consider using decision‐making as a contextual backdrop for exploring information use and behaviour, avoid relying solely on self‐reported behaviour as data, and use a variety of research methods to provide a richer picture of information‐related behaviour. Practice developers need to recognize that understanding the decisions to which research knowledge is to be applied should be a characteristic of any strategy to increase research uptake by nurses.
Daytime sleepiness, sleep habits and occupational accidents among hospital nurses
Authors: Suzuki Kenshu , Ohida Takashi , Kaneita Yoshitaka , Yokoyama Eise , Uchiyama Makoto
Published: October 2005

Aim.  This paper reports a study to determine the prevalence of excessive daytime sleepiness and sleep habits among hospital nurses and to analyse associations between excessive daytime sleepiness and different types of medical error.

Background.  It has been reported that sleep disorders, and the tiredness and sleepiness brought about by sleep disorders may be associated with occupational accidents. However, to our knowledge, there has so far been no report on associations between sleep disorders, excessive daytime sleepiness in particular, and occupational accidents among hospital nurses.

Methods.  The study was a cross‐sectional study targeting 4407 nurses working in eight large general hospitals in Japan. An anonymous self‐administered questionnaire was used to investigate their sleep patterns and experience of occupational accidents. The data were collected in 2003.

Results.  The prevalence of excessive daytime sleepiness among hospital nurses in the present study was 26·0%. A statistically significant relationship was observed between having or not having occupational accidents during the past 12 months and excessive daytime sleepiness. Multiple logistic regression analyses on factors leading to occupational accidents during the past 12 months showed statistically significant associations between (1) drug administration errors and (2) shift work and age, between (1) incorrect operation of medical equipment and (2) excessive daytime sleepiness and age, and between needlestick injuries and age.

Conclusions.  Excessive daytime sleepiness is an important occupational health issue in hospital nurses. It is possible that occupational policies and health promotion measures, such as a provision of sleep hygiene advice and social support at worksites, would be effective in preventing occupational accidents among hospital nurses.
Trust and managerialism: exploring discourses of care
Authors: Gilbert Tony P.
Published: October 2005

Aim.  This paper reports a study that explored the relationship between trust and managerialism through an analysis of professional discourse.

Background.  Managerialism is a distinct set of discourses and practices related to managerial effectiveness, flexibility and consumer responsiveness that have come to characterize debates over the provision of health and welfare services across the developed world. At the same time, trust has attracted increasing academic and political interest. Managerial discourses are critical of healthcare professions and the way they operate. Professional opinions are challenged as representing the interests of professions rather than service users; as a consequence trust is contested. However, where practitioners are both professionals and managers, the boundaries between these discourses become blurred. Moreover, paradoxical development occurs where increasing autonomy for practitioners is accompanied by a strengthening of managerial controls over their activity.

Method.  Discourse analysis was used to explore the text from two genres, academic literature and interviews (n = 17), in the context of community residential services for people with learning disabilities. The study was conducted in 2001.

Findings.  Two broad themes were identified, each with a number of sub‐themes. The first focuses on the relationship between managerialism and trust located around the management of expectations. The second, ‘the politics of care’, explores the way professional and managerial discourse articulate to produce complementary and contradictory positions.

Conclusion.  The colonization of professional activity by managerial discourse has produced a context where professional activity is defined by a series of managerial imperatives; trust, which was once the product of intimate social activity is now shaped through techniques based on distrust such as audits and quality monitoring. Nevertheless, the persistence of tensions between trust and managerialism suggest an ongoing struggle for professional autonomy in the face of increasing managerial controls.
Temporal patterns of genetic variation across a 9‐year‐old aerial seed bank of the shrubBanksia hookeriana(Proteaceae)
Authors: BARRETT LUKE G. , HE TIANHUA , LAMONT BYRON B. , KRAUSS SIEGFRIED L.
Published: October 2005

The pattern of accumulation of genetic variation over time in seed banks is poorly understood. We examined the genetic structure of the aerial seed bank ofBanksia hookerianawithin a single 15‐year‐old population in fire‐prone southwestern Australia, and compared genetic variation between adults and each year of a 9‐year‐old seed bank using amplified fragment length polymorphism (AFLP).B.hookerianais well suited to the study of seed bank dynamics due to the canopy storage of its seeds, and because each annual crop can be identified. A total of 304 seeds from nine crop years and five maternal plants were genotyped, along with 113 plants from the adult population. Genetic variation, as assessed by the proportion of polymorphic markers (Pp) and Shannon's index (I), increased slightly within the seed bank over time, while gene diversity (Hj), did not change.Pp,I, andHjall indicated that genetic variation within the seed bank quickly approached the maximal level detected. Analysis of molecular variance revealed that less than 4% of variation could be accounted for by variation among seeds produced in different years, whereas there was greater differentiation among maternal plants (12.7%), and among individual seeds produced by different maternal plants (83.4%). With increasing population age, offspring generated each year were slightly more outbred, as indicated by an increase in the mean number of nonmaternal markers per offspring. There were no significant differences forHjorIbetween adults and the seed bank. Viability of seeds decreased with age, such that the viability of 9‐year‐old seeds was half that of 2‐year‐old seeds. These results suggest that variable fire frequencies have only limited potential to influence the amount of genetic variation stored within the seed bank ofB.hookeriana.
Native breeds demonstrate high contributions to the molecular variation in northern European sheep
Authors: TAPIO M. , TAPIO I. , GRISLIS Z. , HOLM L.‐E. , JEPPSSON S. , KANTANEN J. , MICEIKIENE I. , OLSAKER I. , VIINALASS H. , EYTHORSDOTTIR E.
Published: October 2005

Population contribution to genetic diversity can be estimated using neutral variation. However, population expansion or hybridization of diverged ancestries may weaken correlation between neutral and non‐neutral variation. Microsatellite variation was studied at 25 loci in 20 native and 12 modern or imported northern European sheep breeds. Breed contributions to total gene diversity, allelic richness and mean allele‐sharing distance between individuals were measured. Indications of changes in population size and admixtures of divergent ancestries were investigated and the extent of inbreeding was estimated. The northern European sheep demonstrated signs of reduction in effective population size. Many old, small populations made a substantial positive contribution to total molecular variation, but populations with several divergent major ancestries did not contribute substantially to molecular variation, with the exception of the Norwegian Rygja sheep. However, several diverged major ancestries may cause it to contribute less to non‐neutral variation than expected from the microsatellite data. Breed uniqueness and within‐breed variability generally had opposite effects on breed contributions to molecular diversity. The degree of inbreeding did not reflect the breed contribution to total gene diversity or allelic richness, but inbred populations increased the mean allele‐sharing distance between individuals. Our study indicates breed conservation to be especially important in maintaining allelic variation in northern European sheep and supports the evolutionary importance of peripheral populations.
Resistance to abomasal nematodes and individual genetic variability in reindeer
Authors: CÔTÉ STEEVE D. , STIEN AUDUN , IRVINE R. JUSTIN , DALLAS JOHN F. , MARSHALL FREDA , HALVORSEN ODD , LANGVATN ROLF , ALBON STEVE D.
Published: October 2005

Resistance to parasites is believed to have a widespread influence on demographic and adaptive processes. In systems where parasites impose a fitness cost on their host, heterozygotes may be selected because they are more resistant to parasites than homozygotes. Our objective was to assess the relationships between genomewide individual heterozygosity and abomasal nematode burdens in female Svalbard reindeer (Rangifer tarandus platyrhynchus) after the effects of host age, locality, season, and year had been accounted for. Samples were obtained from 306 female reindeer that were culled and genotyped at nine microsatellite loci. Reindeer in our study populations are mainly parasitized by the gastrointestinal nematodes Ostertagia gruehneri and Marshallagia marshalli. The infection intensity of each parasite differed between subpopulations, and among host age classes, seasons and years. We found no significant relationships between abomasal worm burdens, or lumen and mucosa larvae, of either O. gruehneri or M. marshalli and individual heterozygosity (or mean d2) alone or in interactions with host age, locality, and year. Although we analysed one of the largest data set available to date on gastrointestinal nematodes of a wild ruminant, we used a typical data set of nine genetic neutral markers that may have had low power to detect heterozygosity–fitness correlations. We conclude that the proportion of the variance in parasite resistance explained by individual heterozygosity for neutral genetic markers is low in Svalbard reindeer and in vertebrates in general, and we suggest that the candidate‐gene approach might be more fruitful for further research on gene–fitness correlations.
Bacterial metal detectors
Authors: Buchanan Susan K.
Published: October 2005

Gram negative bacteria can detect environmental iron using outer membrane transporters (OMTs), and then regulate certain transport genes to take advantage of a readily available iron source. This process begins with an iron complex being bound by an OMT, and results in a signal being sent across the outer membrane, the periplasmic space, and the inner membrane, to a sigma factor that interacts with RNA polymerase and initiates transcription of relevant genes. Many of the interactions contributing to signalling have been observed by genetic and biochemical studies, but structural studies, which potentially show these interactions in molecular detail, have been limited. In this issue, Garcia‐Herrero and Vogel describe an NMR structure of the periplasmic domain of an OMT, which had not been seen in previous X‐ray crystal structures. This domain transmits the ‘iron availability’ signal to the next protein in the signal transduction cascade, which sits in the inner membrane and extends into the periplasm. The new structure extends our knowledge of transporter architecture and suggests how signalling may occur across the outer membrane.
Tetratricopeptide repeats in the type III secretion chaperone, LcrH: their role in substrate binding and secretion
Authors: Edqvist Petra J. , Bröms Jeanette E. , Betts Helen J. , Forsberg Åke , Pallen Mark J. , Francis Matthew S.
Published: October 2005

Non‐flagellar type III secretion systems (T3SSs) transport proteins across the bacterial cell and into eukaryotic cells. Targeting of proteins into host cells requires a dedicated translocation apparatus. Efficient secretion of the translocator proteins that make up this apparatus depends on molecular chaperones. Chaperones of the translocators (also called class‐II chaperones) are characterized by the possession of three tandem tetratricopeptide repeats (TPRs). We wished to dissect the relations between chaperone structure and function and to validate a structural model using site‐directed mutagenesis. Drawing on a number of experimental approaches and focusing on LcrH, a class‐II chaperone from theYersiniaYsc‐Yop T3SS, we examined the contributions of different residues, residue classes and regions of the protein to chaperone stability, chaperone‐substrate binding, substrate stability and secretion and regulation of Yop protein synthesis. We confirmed the expected role of the conserved canonical residues from the TPRs to chaperone stability and function. Eleven mutations specifically abrogated YopB binding or secretion while three mutations led to a specific loss of YopD secretion. These are the first mutations described for any class‐II chaperone that allow interactions with one translocator to be dissociated from interactions with the other. Strikingly, all mutations affecting the interaction with YopB mapped to residues with side chains projecting from the inner, concave surface of the modelled TPR structure, defining a YopB interaction site. Conversely, all mutations preventing YopD secretion affect residues that lie on the outer, convex surface of the triple‐TPR cluster in our model, suggesting that this region of the molecule represents a distinct interaction site for YopD. Intriguingly, one of the LcrH double mutants, Y40A/F44A, was able to maintain stable substrates inside bacteria, but unable to secrete them, suggesting that these two residues might influence delivery of substrates to the secretion apparatus.
Bacteroides fragilis mobilizable transposon Tn5520 requires a 71 base pair origin of transfer sequence and a single mobilization protein for relaxosome formation during conjugation
Authors: Vedantam Gayatri , Knopf Sarah , Hecht David W.
Published: October 2005

Tn5520 is the smallest known bacterial mobilizable transposon and was isolated from an antibiotic resistant Bacteroides fragilis clinical isolate. When a conjugation apparatus is provided in trans, Tn5520 is mobilized (transferred) efficiently within, and from, both Bacteroides spp. and Escherichia coli. Only two genes are present on Tn5520; one encodes an integrase, and the other a multifunctional mobilization (Mob) protein BmpH. BmpH is essential for Tn5520 mobility. The focus of this study was to identify the Tn5520 origin of conjugative transfer (oriT) and to study BmpH‐oriT binding. We delimited the functional Tn5520 oriT to a 71 bp sequence upstream of the bmpH gene. A plasmid vector harbouring this minimal 71 bp oriT was mobilized at the same frequency as that of intact Tn5520. The minimal oriT contains one 17 bp inverted repeat (IR) sequence. We constructed and tested multiple IR mutants and showed that the IR was essential in its entirety for mobilization. A nick site sequence (5′‐GCTAC‐3′) was also identified within the minimal oriT; this sequence resembled nick sites found in plasmids of Gram positive origin. We further showed that mutation of a highly conserved GC dinucleotide in the nick site sequence completely abolished mobilization. We also purified BmpH and showed that it specifically bound a Tn5520 oriT fragment in electrophoretic mobility shift assays. We also identified non‐nick site sequences within the minimal oriT that were essential for mobilization. We hypothesize that transposon‐based single Mob protein systems may contribute to efficient gene dissemination from Bacteroides spp., because fewer DNA processing proteins are required for relaxosome formation.
Protein‐induced DNA bending clarifies the architectural organization of the σ54‐dependent glnAp2 promoter
Authors: Huo Yi‐Xin , Tian Zhe‐Xian , Rappas Mathieu , Wen Jin , Chen Yan‐Cheng , You Cong‐Hui , Zhang Xiaodong , Buck Martin , Wang Yi‐Ping , Kolb Annie
Published: October 2005

σ54‐RNA polymerase (Eσ54) predominantly contacts one face of the DNA helix in the closed promoter complex, and interacts with the upstream enhancer‐bound activator via DNA looping. Up to date, the precise face of Eσ54 that contacts the activator to convert the closed complex to an open one remains unclear. By introducing protein‐induced DNA bends at precise locations between upstream enhancer sequences and the core promoter of the σ54‐dependent glnAp2 promoter without changing the distance in‐between, we observed a strong enhanced or decreased promoter activity, especially on linear DNA templates in vitro. The relative positioning and orientations of Eσ54, DNA bending protein and enhancer‐bound activator on linear DNA were determined by in vitro footprinting analysis. Intriguingly, the locations from which the DNA bending protein exerted its optimal stimulatory effects were all found on the opposite face of the DNA helix compared with the DNA bound Eσ54 in the closed complex. Therefore, these results provide evidence that the activator must approach the Eσ54 closed complexes from the unbound face of the promoter DNA helix to catalyse open complex formation. This proposal is further supported by the modelling of activator‐promoter DNA‐Eσ54 complex.
Etiology and prevention of gastric cancer: a population study in a high risk area of China
Authors: YOU Wei Cheng , LI Ji You , ZHANG Lian , JIN Mao Lin , CHANG Yun Sheng , MA & Kai Jun Ling , PAN Feng
Published: October 2005

A series of studies has been carried out in Linqu County, Shandong Province, China, a high‐risk area for gastric cancer, to investigate the risk factors associated with gastric cancer, precancerous lesions and the prevention of gastric cancer. Our studies showed that sour pancakes (a popular local food), salted foods, cigarette smoking, and family history of gastric cancer were risk factors, whereas fresh vegetables, and intake of vitamin C and calcium were inversely associated with the risk of gastric cancer. The prevalence of chronic atrophic gastritis was approximately 20% in an adult population in Linqu County, intestinal metaplasia was approximately 50%, and dysplasia was approximately 20%. A follow‐up study showed that the relative risk of developing gastric cancer increased with the severity of gastric lesions, and was associated with dietary factors, cigarette smoking and H. pylori infection in this population. The findings strongly support the idea that gastric cancer is primarily determined by environmental factors and develops in a multistep progression of precancerous lesions.
Common single nucleotide polymorphism of hypoxia‐inducible factor‐1α and its impact on the clinicopathological features of esophageal squamous cell carcinoma
Authors: LING Ting Sheng , SHI Rui Hua , ZHANG Guo Xin , ZHU Hong , YU Lian Zhen , DING Xia Feng
Published: October 2005

OBJECTIVE:  Angiogenesis is one of the most important molecular events in solid tumor development and growth, in which hypoxia‐inducible factor (HIF)‐1α is a key regulator and plays an important role. Studies have shown that a single nucleotide polymorphism (C1772T) in the HIF‐1α gene exerts a large effect on the phenotype of human head and neck squamous cell carcinoma and renal cell carcinoma. But the impact of the C1772T polymorphism on the clinicopathological features of human esophageal squamous cell carcinoma (ESCC) remains unknown, and thus it is the main focus of our study.

METHODS:  The C1772T genotype of 95 ESCC patients and 104 healthy controls were studied by using the polymerase chain reaction and restriction fragment length polymorphism. Mutations were confirmed by direct DNA sequencing. The impact of C1772T on tumor size, invasive depth, lymph node metastasis, distant metastasis, histological grade and TNM stage was also studied.

RESULTS:  The genotype frequency observed in the patients and controls was 11.58% versus 10.58%, respectively, for genotype C/T (P > 0.05). Genotype T/T was not found in our study. Larger tumors and a higher rate of lymph node metastasis was found for the C/T group.

CONCLUSIONS:  Although there is no significant difference of genotype distribution between ESCC patients and healthy controls, genotype C/T is associated with larger tumor and higher rate of lymph node metastasis.
Laparoscopic versus open appendectomy in West Bengal, India
Authors: UTPAL De
Published: October 2005

OBJECTIVE:  Laparoscopic appendectomy, although widely practiced, has not gained universal approval. Laparoscopic appendectomy in India is relatively new, and reports regarding its use are few. The aim of this study was to compare laparoscopic with open appendectomy and ascertain its therapeutic benefit, if any, in the overall management of acute appendicitis.

METHODS:  The study group consisted of 279 patients suffering from acute appendicitis. One hundred patients underwent laparoscopic appendectomy (LA) and 179 patients underwent open appendectomy (OA). Comparisons were based on median values for length of hospital stay, operating time, postoperative morbidity, duration of convalescence and operative cost. Mann–Whitney statistics (T) were calculated and, because of the large sample size, the normal deviate test (Z) was used.

RESULTS:  Of the 100 patients who were to receive LA, six patients (6%) had the procedure converted to open surgery. The rate of overall complications (LA 15%vs OA 31.8%; P < 0.001) was significantly lower in patients undergoing LA. The median length of stay was significantly shorter after LA (3 days after LA vs 5 days after OA; P < 0.0001) than after OA. The operating time was shorter (median values: OA 25 min vs LA 28 min; 0.01 < P < 0.05) in patients undergoing OA compared with LA.

CONCLUSION:  For LA, hospital stay was significantly shorter, and the one‐time operative cost appeared to be marginally the same as open surgery. Furthermore, LA was associated with increased clinical comfort in terms of fewer wound infections, faster recovery, earlier return to work and improved cosmesis.
Effects of sodium phenylbutyrate on differentiation and induction of the P21WAF1/CIP1 anti‐oncogene in human liver carcinoma cell lines
Authors: MENG Mei , JIANG Jun Mei , LIU Hui , IN Cheng Yong , ZHU Ju Ren
Published: October 2005

OBJECTIVES:  To explore the effects of sodium phenylbutyrate on the proliferation, differentiation, cell cycle arrest and induction of the P21WAF1/CIP1 anti‐oncogene in human liver carcinoma cell lines Bel‐7402 and HepG2.

METHODS:  Bel‐7402 and HepG2 human liver carcinoma cells were treated with sodium phenylbutyrate at different concentrations. Light microscopy was used to observe morphological changes in the carcinoma cells. Effects on the cell cycle were detected by using flow cytometry. P21WAF1/CIP1 expression was determined by both reverse transcription–polymerase chain reaction and western blotting. Statistical analysis was performed by using one‐way anova and Student's t‐test.

RESULTS:  Sodium phenylbutyrate treatment caused time‐ and dose‐dependent growth inhibition of Bel‐7402 and HepG2 cells. This treatment also caused a decline in the proportion of S‐phase cells and an increase in the proportion of G0/G1 cells. Sodium phenylbutyrate increased the expression of P21WAF1/CIP1.

CONCLUSIONS:  Sodium phenylbutyrate inhibits the proliferation of human liver carcinoma cells Bel‐7402 and HepG2, induces partial differentiation, and increases the expression of P21WAF1/CIP1.
Experimental acute alcohol pancreatitis‐related liver damage and endotoxemia: synbiotics but not metronidazole have a protective effect
Authors: MAROTTA F , BARRETO R , WU CC , NAITO Y , GELOSA F , LORENZETTI A , YOSHIOKA M , FESCE E
Published: October 2005

OBJECTIVE:  The aim of this study was to test the effect of gut manipulation by either novel synbiotics or by metronidazole on either endotoxemia or the severity of liver damage in the course of acute pancreatitis from alcohol ingestion.

METHODS:  Sprague–Dawley rats were fed for 1 week through an intragastric tube a liquid diet with either: (i) 1 mL t.i.d. of a mixture of synbiotics (Lactobacillus acidophilus, Lactobacillus helveticus and Bifidobacterium in an enriched medium); (ii) 20 mg/kg t.i.d. metronidazole; or (iii) standard diet. Then, acute pancreatitis was induced by caerulein and when the disease was full‐blown, rats were fed an alcohol‐rich diet. Synbiotic and metronidazole treatment was given for a further 2 weeks. Transaminase and endotoxemia levels were measured before treatment, after 6 h, after 24 h and 2 weeks later, at the time the rats were killed. Liver samples were obtained for histological analysis.

RESULTS:  Synbiotics but not metronidazole improved the acute pancreatitis‐induced increase in endotoxemia and transaminase levels. The addition of alcohol worsened these variables to a limited extent in the synbiotic‐treated group, while metronidazole had a negative effect on liver damage.

CONCLUSIONS:  Gut flora pretreatment with synbiotics was able to effectively protect against endotoxin/bacterial translocation, as well as liver damage in the course of acute pancreatitis and concomitant heavy alcohol consumption. The beneficial effect of synbiotics on liver histology seems to be correlated with endotoxemia. Metronidazole did not produce such a beneficial effect; in fact, it further worsened liver damage when alcohol was added to the background of ongoing acute pancreatic inflammation.
Comparison of the efficacy of 1‐day high‐dose quadruple therapy versus 7‐day triple therapy for treatment of Helicobacter pylori infection
Authors: ZHENG Qing , PAN Yan , ZHANG Lin , XIAO Shu Dong
Published: October 2005

BACKGROUND:  The proton pump inhibitor (PPI)‐based 7‐day triple therapy is the regimen with the highest cure rates for eradication of Helicobacter pylori infection and has been recommended as the first‐line regimen in the world. It had been reported that a 1‐day quadruple therapy could also successfully cure 95% of the H. pylori infected patients.

OBJECTIVES:  To observe the efficacy of 1‐day high‐dose quadruple therapy versus 7‐day triple therapy for treatment of H. pylori infection, and to observe side‐effects of the two different regimens.

METHODS:  This randomized, open, parallel‐controlled study was conducted at Renji Hospital between November 2004 to March 2005. A total of 80 consecutive patients with non‐ulcer dyspepsia, who were H. pylori positive proven by both rapid urease test and histology were included and randomly assigned to 1‐day quadruple therapy or 7‐day triple therapy. Thirty‐nine patients were administered with 1‐day high‐dose quadruple therapy including esomeprazole 40 mg b.i.d., colloidal bismuth subcitrate 440 mg q.i.d., amoxicillin 2 g q.i.d. and metronidazole (400 mg q.i.d.) for 1 day. Forty‐one patients received a standard 7‐day triple therapy consisting of esomeprazole 20 mg b.i.d., clarithromycin 500 mg b.i.d. and amoxicillin 1 g b.i.d. for 7 days. The eradication rates were evaluated by the 13C‐urea breath test at least 4 weeks after completion of a course treatment.

RESULTS:  Seventy‐seven patients completed the trial and three patients dropped out. The eradication rates in the 1‐day therapeutic group and the 7‐day therapeutic group were 39.5% (15/38) and 84.6% (33/39), respectively. There was a statistically significant difference between the two groups (P < 0.0001). Short‐lasting and self‐limiting side effects including thirst, a metallic taste, diarrhea and abdominal pain were reported in three patients (7.9%) in the 1‐day group and seven patients (18%) in the 7‐day group (P = 0.31).

CONCLUSIONS:  A 1‐day high‐dose quadruple therapy with amoxicillin, metronidazole, bismuth salt, and esomeprazole is not effective for eradication of H. pylori compared with the standard 7‐day triple therapy.
Stem Cells: Classifications, Controversies, and Clinical Applications
Authors: Fortier Lisa A.
Published: October 2005

The application of stem cells in regenerative and reparative therapies is emerging in surgery. Published information can lead to an over simplified view of stem cells with respect to their definitions, tissues of origin, abilities to differentiate into tissue lineages, and their capacity for functional tissue regeneration. The goals of this review article are to define embryonic and adult stem cells, compare differences between them, and summarize their potential clinical applications.