bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights into the mechanisms of myosin and kinesin molecular motors from the single-molecule unbinding force measurements
Authors: Mikhailenko Sergey V. , Oguchi Yusuke , Ishiwata Shin'ichi
Published: April 2010

In cells, ATP (adenosine triphosphate)-driven motor proteins, both cytoskeletal and nucleic acid-based, operate on their corresponding ‘tracks’, that is, actin, microtubules or nucleic acids, by converting the chemical energy of ATP hydrolysis into mechanical work. During each mechanochemical cycle, a motor proceeds via several nucleotide states, characterized by different affinities for the ‘track’ filament and different nucleotide (ATP or ADP) binding kinetics, which is crucial for a motor to efficiently perform its cellular functions. The measurements of the rupture force between the motor and the track by applying external loads to the individual motor–substrate bonds in various nucleotide states have proved to be an important tool to obtain valuable insights into the mechanism of the motors' performance. We review the application of this technique to various linear molecular motors, both processive and non-processive, giving special attention to the importance of the experimental geometry.
DNA transposon dynamics in populations ofDaphnia pulexwith and without sex
Authors: Schaack Sarah , Pritham Ellen J. , Wolf Abby , Lynch Michael
Published: April 2010

We investigate the role of recombination in transposable element (TE) proliferation in the cyclical parthenogen,Daphnia pulex. Recombination provides a mechanism by which the rate of both TE gain and loss can be accelerated, a duality that has long intrigued many biologists interested in the influence of sex on mutation accumulation. We compared TE loads among populations ofD. pulexwhere sex occurs regularly (cyclical parthenogens or ‘sexuals’) with those in which the ability to reproduce sexually has been completely lost (obligate ‘asexuals’) for six different families of DNA transposons. Transposon display assays showed that sexuals have more TEs than asexuals, contrary to the expectations under Muller's ratchet but consistent with the idea that sex facilitates TE spread. Sexuals also exhibit higher insertion site polymorphism among lineages, as predicted because recombination accelerates rates of loss and gain. Asexuals, however, have proportionally more singletons (loci occupied in a single isolate), which differs from previous studies where selfing and outcrossing were used as a proxy for high and low recombination. Our multi-element survey reveals that the impact of sex on TE proliferation is consistent among different Class II TE families and we discuss the genomic consequences of different reproductive strategies over long time periods.
A rift between implicit and explicit conditioned valence in human pain relief learning
Authors: Andreatta Marta , Mühlberger Andreas , Yarali Ayse , Gerber Bertram , Pauli Paul
Published: April 2010

Pain is aversive, but does the cessation of pain (‘relief’) have a reward-like effect? Indeed, fruitflies avoid an odour previously presented before a painful event, but approach an odour previously presented after a painful event. Thus, event-timing may turn punishment to reward. However, is event-timing also crucial in humans who can have explicit cognitions about associations? Here, we show that stimuli associated with pain-relief acquire positive implicit valence but are explicitly rated as aversive. Specifically, the startle response, an evolutionarily conserved defence reflex, is attenuated by stimuli that had previously followed a painful event, indicating implicit positive valence of the conditioned stimulus; nevertheless, participants explicitly evaluate these stimuli as ‘emotionally negative’. These results demonstrate a rift between the implicit and explicit conditioned valence induced by pain relief. They might explain why humans in some cases are attracted by conditioned stimuli despite explicitly judging them as negative.
In search of the chemical basis for MHC odourtypes
Authors: Kwak Jae , Willse Alan , Preti George , Yamazaki Kunio , Beauchamp Gary K.
Published: April 2010

Mice can discriminate between chemosignals of individuals based solely on genetic differences confined to the major histocompatibility complex (MHC). Two different sets of compounds have been suggested: volatile compounds and non-volatile peptides. Here, we focus on volatiles and review a number of publications that have identified MHC-regulated compounds in inbred laboratory mice. Surprisingly, there is little agreement among different studies as to the identity of these compounds. One recent approach to specifying MHC-regulated compounds is to study volatile urinary profiles in mouse strains with varying MHC types, genetic backgrounds and different diets. An unexpected finding from these studies is that the concentrations of numerous compounds are influenced by interactions among these variables. As a result, only a few compounds can be identified that are consistently regulated by MHC variation alone. Nevertheless, since trained animals are readily able to discriminate the MHC differences, it is apparent that chemical studies are somehow missing important information underlying mouse recognition of MHC odourtypes. To make progress in this area, we propose a focus on the search for behaviourally relevant odourants rather than a random search for volatiles that are regulated by MHC variation. Furthermore, there is a need to consider a ‘combinatorial odour recognition’ code whereby patterns of volatile metabolites (the basis for odours) specify MHC odourtypes.
Chaotic Red Queen coevolution in three-species food chains
Authors: Dercole Fabio , Ferriere Regis , Rinaldi Sergio
Published: April 2010

Coevolution between two antagonistic species follows the so-called ‘Red Queen dynamics’ when reciprocal selection results in an endless series of adaptation by one species and counteradaptation by the other. Red Queen dynamics are ‘genetically driven’ when selective sweeps involving new beneficial mutations result in perpetual oscillations of the coevolving traits on the slow evolutionary time scale. Mathematical models have shown that a prey and a predator can coevolve along a genetically driven Red Queen cycle. We found that embedding the prey–predator interaction into a three-species food chain that includes a coevolving superpredator often turns the genetically driven Red Queen cycle into chaos. A key condition is that the prey evolves fast enough. Red Queen chaos implies that the direction and strength of selection are intrinsically unpredictable beyond a short evolutionary time, with greatest evolutionary unpredictability in the superpredator. We hypothesize that genetically driven Red Queen chaos could explain why many natural populations are poised at the edge of ecological chaos. Over space, genetically driven chaos is expected to cause the evolutionary divergence of local populations, even under homogenizing environmental fluctuations, and thus to promote genetic diversity among ecological communities over long evolutionary time.
Nanostructure and mechanics of mummified type I collagen from the 5300-year-old Tyrolean Iceman
Authors: Janko Marek , Zink Albert , Gigler Alexander M. , Heckl Wolfgang M. , Stark Robert W.
Published: April 2010

Skin protects the body from pathogens and degradation. Mummified skin in particular is extremely resistant to decomposition. External influences or the action of micro-organisms, however, can degrade the connective tissue and lay the subjacent tissue open. To determine the degree of tissue preservation in mummified human skin and, in particular, the reason for its durability, we investigated the structural integrity of its main protein, type I collagen. We extracted samples from the Neolithic glacier mummy known as ‘the Iceman’. Atomic force microscopy (AFM) revealed collagen fibrils that had characteristic banding patterns of 69 ± 5 nm periodicity. Both the microstructure and the ultrastructure of dermal collagen bundles and fibrils were largely unaltered and extremely well preserved by the natural conservation process. Raman spectra of the ancient collagen indicated that there were no significant modifications in the molecular structure. However, AFM nanoindentation measurements showed slight changes in the mechanical behaviour of the fibrils. Young's modulus of single mummified fibrils was 4.1 ± 1.1 GPa, whereas the elasticity of recent collagen averages 3.2 ± 1.0 GPa. The excellent preservation of the collagen indicates that dehydration owing to freeze-drying of the collagen is the main process in mummification and that the influence of the degradation processes can be addressed, even after 5300 years.
The nuclear receptor tailless induces long-term neural stem cell expansion and brain tumor initiation
Authors: Liu Hai-Kun , Wang Ying , Belz Thorsten , Bock Dagmar , Takacs Andrea , Radlwimmer Bernhard , Barbus Sebastian , Reifenberger Guido , Lichter Peter , Schütz Günther
Published: April 2010

Malignant gliomas are the most common primary brain tumors, and are associated with frequent resistance to therapy as well as poor prognosis. Here we demonstrate that the nuclear receptor tailless (Tlx), which in the adult is expressed exclusively in astrocyte-like B cells of the subventricular zone, acts as a key regulator of neural stem cell (NSC) expansion and brain tumor initiation from NSCs. Overexpression of Tlx antagonizes age-dependent exhaustion of NSCs in mice and leads to migration of stem/progenitor cells from their natural niche. The increase of NSCs persists with age, and leads to efficient production of newborn neurons in aged brain tissues. These cells initiate the development of glioma-like lesions and gliomas. Glioma development is accelerated upon loss of the tumor suppressor p53. Tlx-induced NSC expansion and gliomagenesis are associated with increased angiogenesis, which allows for the migration and maintenance of brain tumor stem cells in the perivascular niche. We also demonstrate that Tlx transcripts are overexpressed in human primary glioblastomas in which Tlx expression is restricted to a subpopulation of nestin-positive perivascular tumor cells. Our study clearly demonstrates how NSCs contribute to brain tumorgenesis driven by a stem cell-specific transcription factor, thus providing novel insights into the histogenesis and molecular pathogenesis of primary brain tumors.
The recombination landscape of the zebra finch Taeniopygia guttata genome
Authors: Backström Niclas , Forstmeier Wolfgang , Schielzeth Holger , Mellenius Harriet , Nam Kiwoong , Bolund Elisabeth , Webster Matthew T. , Öst Torbjörn , Schneider Melanie , Kempenaers Bart , Ellegren Hans
Published: April 2010

Understanding the causes and consequences of variation in the rate of recombination is essential since this parameter is considered to affect levels of genetic variability, the efficacy of selection, and the design of association and linkage mapping studies. However, there is limited knowledge about the factors governing recombination rate variation. We genotyped 1920 single nucleotide polymorphisms in a multigeneration pedigree of more than 1000 zebra finches (Taeniopygia guttata) to develop a genetic linkage map, and then we used these map data together with the recently available draft genome sequence of the zebra finch to estimate recombination rates in 1 Mb intervals across the genome. The average zebra finch recombination rate (1.5 cM/Mb) is higher than in humans, but significantly lower than in chicken. The local rates of recombination in chicken and zebra finch were only weakly correlated, demonstrating evolutionary turnover of the recombination landscape in birds. The distribution of recombination events was heavily biased toward ends of chromosomes, with a stronger telomere effect than so far seen in any organism. In fact, the recombination rate was as low as 0.1 cM/Mb in intervals up to 100 Mb long in the middle of the larger chromosomes. We found a positive correlation between recombination rate and GC content, as well as GC-rich sequence motifs. Levels of linkage disequilibrium (LD) were significantly higher in regions of low recombination, showing that heterogeneity in recombination rates have left a footprint on the genomic landscape of LD in zebra finch populations.
Pronounced inter- and intrachromosomal variation in linkage disequilibrium across the zebra finch genome
Authors: Stapley Jessica , Birkhead Tim R. , Burke Terry , Slate Jon
Published: April 2010

The extent of nonrandom association of alleles at two or more loci, termed linkage disequilibrium (LD), can reveal much about population demography, selection, and recombination rate, and is a key consideration when designing association mapping studies. Here, we describe a genome-wide analysis of LD in the zebra finch (Taeniopygia guttata) using 838 single nucleotide polymorphisms and present LD maps for all assembled chromosomes. We found that LD declined with physical distance approximately five times faster on the microchromosomes compared to macrochromosomes. The distribution of LD across individual macrochromosomes also varied in a distinct pattern. In the center of the macrochromosomes there were large blocks of markers, sometimes spanning tens of mega bases, in strong LD whereas on the ends of macrochromosomes LD declined more rapidly. Regions of high LD were not simply the result of suppressed recombination around the centromere and this pattern has not been observed previously in other taxa. We also found evidence that this pattern of LD has remained stable across many generations. The variability in LD between and within chromosomes has important implications for genome wide association studies in birds and for our understanding of the distribution of recombination events and the processes that govern them.
Copy number variation, chromosome rearrangement, and their association with recombination during avian evolution
Authors: Völker Martin , Backström Niclas , Skinner Benjamin M. , Langley Elizabeth J. , Bunzey Sydney K. , Ellegren Hans , Griffin Darren K.
Published: April 2010

Chromosomal rearrangements and copy number variants (CNVs) play key roles in genome evolution and genetic disease; however, the molecular mechanisms underlying these types of structural genomic variation are not fully understood. The availability of complete genome sequences for two bird species, the chicken and the zebra finch, provides, for the first time, an ideal opportunity to analyze the relationship between structural genomic variation (chromosomal and CNV) and recombination on a genome-wide level. The aims of this study were therefore threefold: (1) to combine bioinformatics, physical mapping to produce comprehensive comparative maps of the genomes of chicken and zebra finch. In so doing, this allowed the identification of evolutionary chromosomal rearrangements distinguishing them. The previously reported interchromosomal conservation of synteny was confirmed, but a larger than expected number of intrachromosomal rearrangements were reported; (2) to hybridize zebra finch genomic DNA to a chicken tiling path microarray and identify CNVs in the zebra finch genome relative to chicken; 32 interspecific CNVs were identified; and (3) to test the hypothesis that there is an association between CNV, chromosomal rearrangements, and recombination by correlating data from (1) and (2) with recombination rate data from a high-resolution genetic linkage map of the zebra finch. We found a highly significant association of both chromosomal rearrangements and CNVs with elevated recombination rates. The results thus provide support for the notion of recombination-based processes playing a major role in avian genome evolution.
Isolation of Drosophila Egg Chambers for Imaging: Figure 1
Authors: Parton Richard M. , Vallés Ana Maria , Dobbie Ian M. , Davis Ilan
Published: April 2010

INTRODUCTION

The fruit fly Drosophila melanogaster is an important model for basic research into the molecular mechanisms underlying cell function and development, as well as a major biomedical research tool. A significant advantage of Drosophila is the ability to apply live cell imaging to a variety of living tissues that can be dissected and imaged in vivo, ex vivo, or in vitro. Drosophila egg chambers, for example, have proven to be a useful model system for studying border cell migration, Golgi unit transport, the rapid movement of mRNA and protein particles, and the role of microtubules in meiosis and oocyte differentiation. A crucial first step before imaging is preparation of the experimental material to ensure physiological relevance and to achieve the best conditions for image quality. Early- to mid-stage egg chambers cannot be mounted in an aqueous-based medium, because this causes a change in microtubule organization and follicle cell morphology. Such egg chambers survive better in Halocarbon oil, which allows free diffusion of oxygen, has low viscosity, and thus prevents dehydration and hypoxia. With a refractive index similar to glycerol, Halocarbon oil also has good optical properties for imaging. It also provides a good environment for injection and is particularly useful for long-term imaging of embryos. However, unlike with aqueous solutions, changes in the medium are not possible. This protocol describes the isolation of Drosophila egg chambers.
Drosophila Macrophage Preparation and Screening
Authors: Parton Richard M. , Vallés Ana Maria , Dobbie Ian M. , Davis Ilan
Published: April 2010

INTRODUCTION

Drosophila plasmatocytes, also known as macrophages, are part of the Drosophila innate immune system and also have roles during development. In late-stage embryos, it is possible to image macrophage migration in situ during development and when they converge at sites of wounding. This protocol describes the isolation of macrophages from third instar Drosophila larvae. The macrophages can be cultured for several hours, and fluorescently labeled macrophages can be screened using a fluorescence-imaging system.
Introduction of Green Fluorescent Protein (GFP) into Hippocampal Neurons through Viral Infection
Authors: Malinow Roberto , Hayashi Yasunori , Maletic-Savatic Mirjana , Zaman Shahid H. , Poncer Jean-Christophe , Shi Song-Hai , Esteban José A. , Osten Pavel , Seidenman Ken
Published: April 2010

INTRODUCTION

Expression of green fluorescent protein (GFP), its more fluorescent mutant forms (e.g., EGFP [enhanced GFP]), or their fusion protein derivatives, affords a number of informative possibilities in cellular neuroscience. EGFP is a soluble protein and appears to be homogeneously distributed within the cytosol of neurons when expressed. Thus, it reveals the structure of the neuron, including the cell body, and axonal and dendritic arbors. It is also sufficiently bright to reveal detailed structures such as axonal boutons and dendritic spines. When expressed as a fusion protein, EGFP can provide information about the distribution characteristics of the proteins within neurons. Furthermore, during single-cell electrophysiological studies, such expression can direct the investigator to record from a cell carrying a foreign gene. In this protocol, we describe the use of the Sindbis pseudovirus expression system to deliver GFP to neurons. Sindbis is a member of the alphaviruses, which are plus-stranded RNA viruses. This protocol uses the DH(26S) strain, which preferentially infects neurons over glia (50:1). Two infection methods are given: one for dissociated hippocampal cultured neurons and one for organotypic hippocampal slices.
CTAB-PAGE
Authors: Simpson Richard J.
Published: April 2010

INTRODUCTION

Although SDS-PAGE is the method of choice for most denaturing gel electrophoresis procedures, the anionic detergent SDS still presents some drawbacks. For example, SDS forms crystals at low temperatures and, in some cases, causes proteins to aggregate or precipitate. In addition, some proteins are not well-resolved in SDS gels or may migrate anomalously. In these situations, the use of a cationic detergent for PAGE offers an alternative approach. The system described in this protocol uses the cationic detergent cetyltrimethyl ammonium bromide (CTAB) and includes a stacking gel based on the zwitterion arginine (used as a stacking agent) and tricine (N-tris[hydroxymethyl]-methylglycine) used as a counterion and buffer. Some proteins separated on the CTAB electrophoresis system retain their native enzymatic activity, provided the samples are prepared without boiling and without the addition of a reducing agent.
Rapid Coomassie Blue Staining of Protein Gels
Authors: Simpson Richard J.
Published: April 2010

INTRODUCTION

Coomassie brillant blue R250 (CBR-250) and silver staining are the most widely used methods for the routine visualization of proteins separated by SDS-PAGE. CBR-250 is an organic dye that complexes with basic amino acids, such as arginine, lysine, and histidine, as well as tyrosine. Conventional CBR-250 staining is capable of detecting as little as 30-100 ng of protein, but sensitivity can be improved by performing the staining and destaining at elevated temperatures. The method described in this protocol, which is a modified version of the conventional Coomassie protocol, speeds up the destaining process for faster results with increased sensitivity and is compatible with mass-spectrometry-based methods for identifying proteins.
Multiply Primed Rolling-Circle Amplification Method for the Amplification of Circular DNA Viruses
Authors: Stevens Hans , Rector Annabel , Van Ranst Marc
Published: April 2010

INTRODUCTION

The use of whole genome amplification and analysis of viruses is of increasing importance, as data generated using these methods are currently used for clinical diagnostics, epidemiological studies, phylogenetic analyses, and studies of genome organization and evolution. The best known amplification method for DNA is the polymerase chain reaction (PCR). This technique, however, has drawbacks: PCR produces relatively small amplicons and also requires prior knowledge of sequence data for the construction of the required consensus or degenerate primers. For circular DNA templates, it is possible to overcome these drawbacks by using the multiply primed rolling-circle amplification (RCA) technique, which mimics the rolling-circle mechanism that occurs in nature for replication of circular DNA molecules, e.g., plasmids. The RCA protocol described here is optimized for the amplification of circular DNA virus genomes.
rAAV9--A Human-Derived Adeno-Associated Virus Vector for Efficient Transgene Expression in Mouse Cingulate Cortex: Figure 1.
Authors: Jakovcevski Mira , Guo Yin , Su Qin , Gao Guangping , Akbarian Schahram
Published: April 2010

INTRODUCTION

The rostro-medial cortex of the mouse and rat, considered the functional homolog to the primate prefrontal cortex (PFC), is of growing importance for preclinical models of schizophrenia and other neurodevelopmental diseases for which symptoms typically emerge in adolescence and early adulthood. Therefore, in order to explore molecular mechanisms operating during these critical stages of PFC development, it will be important to develop an efficient gene delivery system for the PFC of juvenile animals. To this end, adeno-associated virus (AAV)-based systems are increasingly used in mice for targeted gene delivery in specific brain regions such as the hippocampus. Strikingly, there is very little literature on vector-mediated gene expression in the rostro-medial cortex. In addition, multiple AAV serotypes exist based on differences in their envelope capsid proteins. However, to date, the large majority of studies in the central nervous system (CNS) have utilized the AAV2 serotype. This is typically limited to a very focal transduction pattern and therefore is not ideal for the murine PFC, which occupies several square millimeters in the rostral hemisphere. Here, we introduce a protocol for efficient, AAV9-serotype-mediated gene delivery in juvenile (postnatal day 21) and young adult PFC, resulting in long-lasting transgene expression.
Passage of pathogenic microorganisms through breathing system filters used in anaesthesia and intensive care
Authors: Scott D. H. T. , Fraser S. , Willson P. , Drummond G. B. , Baillie J. K.
Published: April 2010

Invasive ventilation poses a risk of respiratory infection that can be drug‐resistant. One means of reducing transmission of infection is the use of a breathing system filter. Filters are intended to be used with dry gas. Current international standards do not require that filters prevent bacterial transfer when wet. It is not known whether microorganisms pass through wet filters, but theory predicts that this might occur. We tested six filters from three different manufacturers. We passed a suspension of microorganisms through the filters using the least pressure necessary, and incubated a sample of the filtrate on blood agar. All the filters tested allowed free passage of both Candida albicans and coagulase‐negative staphylococci. The median (IQR [range]) pressure required for fluid to flow across the filter varied greatly between different filter types (20 (0–48 [0–138]) cmH2O). We conclude that even large microorganisms pass across moist breathing system filters in conditions that are found in clinical practice.
Three‐dimensional seismic characterisation of large‐scale sandstone intrusions in the lower Palaeogene of the North Sea: completely injected vs. in situ remobilised sandbodies
Authors: Szarawarska Ewa , Huuse Mads , Hurst Andrew , De Boer Wytze , Lu Liwei , Molyneux Steven , Rawlinson Peter
Published: April 2010

A large number of km‐scale, saucer‐shaped sandstone bodies of enigmatic origin have recently been documented in the North Sea and the Faroe Shetland Basin. This study utilises three‐dimensional seismic data, calibrated by well data, to examine two such bodies that exhibit very similar saucer‐shaped geometries in cross‐section. The Volund and Danica structures, located 250 km apart are interpreted as end members of a spectrum of large‐scale remobilised and injected sandstones present in the North Sea Palaeogene. Both are characterised by a central 1–2 km‐wide low area surrounded by a discordant, 2–300 m tall inclined dyke complex, that tips out into a bedding concordant body interpreted as a shallow‐level sill and/or partly extruded sandstone. The origin of the central concordant sandstone body as either injected (laccolith) or depositional is of key importance to a complete understanding of the origin and prospectivity of these structures. The key criteria for recognising an injected vs. depositional origin for the central concordant sandbody are: (1) a flat, nonerosional base; (2) ‘jack‐up’ of the overburden equal to the underlying sand thickness; (3) equally thick layers of encasing mudstones; and (4) paleogeographic context. This study suggests that the Danica structure was deposited as a channel sandstone and remobilised in situ; this led to the formation of wing‐like intrusions along the channel margins. In contrast, the Volund structure overburden displays a forced‐fold geometry, arguably a diagnostic feature of an intrusive origin. The ability to recognise and differentiate completely injected vs. in situ remobilised sandbodies is important both from a basin analysis, hydrocarbon exploration and rock mechanics points of view. An improved understanding of these aspects will lead to a reduction of risks associated with the exploration and development of such a sandbody and an enhanced understanding of sediment remobilisation and fluid flow on a basin scale.
Sand‐rich injectites in the context of short‐lived and long‐lived fluid flow
Authors: Jonk Rene
Published: April 2010

Sand‐rich injectites are a common attribute of clastic sedimentary successions, and they have received increased attention in the last decade by geoscientists and engineers dealing with shallow subsurface flow and retention of aqueous and hydrocarbon fluids. Injectites form due to fluidized flow of sediment‐entraining fluids through high‐permeability strata. Given that sediment entrainment is confined to high‐permeability sediments with low horizontal effective stress and negligible cementation, the formation of sand‐rich injectites is restricted to the first kilometre of burial, where sand‐rich sediments are prone to fluidization and clay‐rich sediments are generally more cohesive and may hydraulically fracture to allow the creation of injectites. When reviewing conditions that may lead to aqueous and hydrocarbon flow within this shallow section at velocities that may cause sand fluidization and injection, we can rule out geologic time‐scale processes (disequilibrium compaction, hydrocarbon migration, and lateral pressure transfer) as plausible causes. This emphasizes the need for high‐strain‐rate processes to cause rapid fluid overpressuring and flow associated with sand injection. Earthquake‐induced shaking, instantaneous loading and release of overpressured fluids along moving fault planes are the most likely causes of sand remobilization and injection and these processes may enforce each other during tectonic stress‐release events. An additional mechanism that may trigger sand‐rich injections is the mechanical failure of shallow oil accumulations, particularly as the fluidization velocity of sand entrained in oil can be several orders of magnitude lower than for sand entrained in aqueous fluids, particularly if the oil is biodegraded (and thus has a high dynamic viscosity). Flow of hydrocarbon gas is unlikely to cause sand injection, although gas dissolved in upward‐flowing aqueous fluids may evolve at or near the surface as pressures in the aqueous phase drop.
Captivity affects immune redistribution to skin in a wild bird
Authors: Kuhlman Joshua R. , Martin Lynn B.
Published: April 2010

1. Effects of stressors on immune functions have long been studied, but most have focused on chronic stressors, which tend to be immunosuppressive. More recently, an emphasis has been placed on identifying and understanding effects of transient, unpredictable stressors, especially whether and how they affect movement of immune cells to body areas in need of rapid protection. These latter effects have been termed, immunoredistribution.

2. In this study, we surgically implanted small gelatin sponges subcutaneously to measure leucocyte infiltration to skin in house sparrows, Passer domesticus. First, we evaluated whether wild birds exhibit leucocyte infiltration to skin in response to a transient stressor (restraint) as seen in laboratory rodents. Secondly, we examined effects of captivity on leucocyte infiltration of wild sparrows, expecting long‐duration captivity to impose chronic stress and thus reduce leucocyte infiltrations. In particular, we expected continuous elevation of the avian stress hormone, corticosterone (CORT), to dampen skin infiltration of leucocytes in birds kept in captivity for short‐term (1–2 days) and more so long‐term (1 month) periods compared with wild‐caught individuals.

3. As in lab rodents, house sparrows exhibited cutaneous leucocyte infiltration, but 1 h of restraint prior to surgery did not influence the magnitude of cellular infiltration. The leucocyte infiltration response was influenced by captivity, however, with short‐term captive birds (1–2 days) exhibiting less leucocyte influx than long‐term (30 days) and wild individuals. Interestingly, the profile of cellular infiltrates changed with time in captivity with a dramatic shift away from lymphocytes and towards heterophils in long‐term captive birds. Placement in captivity did not affect total circulating leucocytes, however, lymphocytes decreased in numbers in wild birds in short‐term captivity. CORT followed the expected pattern with the highest baseline levels in short‐term captives, intermediate levels in long‐term captives and lowest levels in wild‐caught birds. Stress responses were not affected by time in captivity.

4. These results indicate that an integral aspect of immunoredistribution occurs in wild birds but future efforts to understand the ecological and evolutionary forces that have shaped this immune response must account for the confounding effects of captivity and attempt to understand the proximate and ultimate basis for heterophilia and lymphopenia with chronic stress.
Functional analysis of the skin‐swelling response to phytohaemagglutinin
Authors: Vinkler Michal , Bainová Hana , Albrecht Tomáš
Published: April 2010

1. The phytohaemagglutinin (PHA) skin‐swelling test is widely used in immunoecology and ecotoxicology to estimate cell‐mediated immunity. Although often presumed, the involvement of T cells in generating an immune response to PHA in vivo remains unclear.

2. To investigate the mechanism triggering this response we have compared in zebra finch (Taeniopygia guttata) the immune responses to two PHA isolectins differing in their biological properties and one control protein.

3. In Experiment I, we applied PHA‐P (the commonly used L and E isolectin mixture) into one wing‐web and bovine serum allbumin (BSA) into the other. The swelling response to PHA‐P was significantly stronger than to BSA confirming that the reaction is governed by PHA‐specific properties.

4. In Experiment II, purified PHA‐L (the T‐cell‐stimulating isolectin) and PHA‐E (the erythroagglutinating isolectin) were compared. Contrary to our expectations, PHA‐E induced a significantly stronger swelling response than PHA‐L. Histological analysis revealed significantly higher quantities of erythrocytes and thrombocytes in PHA‐E‐treated patagia. Nevertheless, there was a positive correlation between the magnitudes of these swellings.

5. In Experiment III, we tested whether the results obtained by the application of PHA‐P and pure PHA‐L differ. Here, we failed to find any significant difference between these two preparations in their immunostimulatory activity. Magnitudes of the PHA‐L‐ and PHA‐P‐induced swellings were positively correlated.

6. To the best of our knowledge this is the first study to compare the biological activity of purified PHA fractions in vivo and also the first to show the importance of erythroagglutination in the development of an inflammatory response to PHA‐P.

7. Our results indicate that the skin‐swelling test using PHA‐P reliably mirrors the individual general proinflammatory potential. However, the immunological background of the test is highly complex and the test results cannot be interpreted as measurements of the adaptive immunity or T‐cell activity. This interpretational change importantly alters our view on the test results regarding the costs of the response or the evolutionary immunological adaptations.
Trait‐mediated effect of arbuscular mycorrhiza on the competitive effect and response of a monopolistic species
Authors: Gross Nicolas , Le Bagousse‐Pinguet Yoann , Liancourt Pierre , Urcelay Carlos , Catherine Roumet , Lavorel Sandra
Published: April 2010

1. Cessation of agricultural practices often leads to a dramatic decline in species diversity concomitant with the increase in abundance of monopolistic species, which have been hypothesized to be strongly arbuscular mycorrhiza (AM) dependent. AM can affect competitive interactions and influence plant species diversity. Few studies have tested AM effects on the competitive strategy of monopolistic species although it has been shown to be a key parameter to explain their high dominance. In addition, it is not clear whether AM effects on plant interactions can be explained by density‐mediated interactions or by trait‐mediated interactions.

2. We measured the competitive effect of Festuca paniculata, a widespread monopolistic species from subalpine communities, on itself and on two additional target species with and without AM (benomyl treatment) under contrasted fertilised treatments. AM effects on target species traits were quantified.

3. The three target species exhibited contrasted AM dependency and only F. paniculata was positively affected by AM presence in fertilised conditions. In the fertilised treatment, AM decreased intra‐specific competition and increased inter‐specific competition. Changes in competitive responses were explained by the AM effect on P inflow and species lateral spread.

4. Our results highlight AM ability to modify the performance of monopolistic species under different environmental conditions. AM provide an important mechanism by which monopolistic species can maintain a high level of dominance and dramatically decrease species diversity following agricultural abandonment.
Variation in characteristics of islets of Langerhans in insulin‐resistant, diabetic and non‐diabetic‐rat strains
Authors: Jones Huw Bowen , Nugent David , Jenkins Richard
Published: April 2010

Assessment of the histopathological and plasma biochemical characteristics of diabetic and non‐diabetic rat strains [Han and AP Wistar, lean and obese Zucker Fatty (ZF), and lean and obese Zucker Diabetic Fatty (ZDF) rats] was performed at 6 or 14 weeks of age. Wistar and lean ZF and ZDF rats showed no or minimal islet pathology or plasma biochemical alterations at both timepoints. Obese ZFs were euglycaemic at both timepoints and mildly and severely hyperinsulinaemic at 6 and 14 weeks respectively. Islet morphology was normal at 6 weeks but at 14 weeks, islet hyperplasia was present with a minority showing degenerative changes namely, β‐cell vacuolation, vascular congestion and haemorrhage with minimal mononuclear cell and T lymphocytic infiltration. Obese ZDFs were euglycaemic and moderately hyperinsulinaemic at 6 weeks and severely hyperglycaemic with minor hypoinsulinaemia at 14 weeks. Obese ZDFs at 6 weeks showed mainly normal islets with some displaying degeneration (ranging from β‐cell vacuolation alone to the features described above). At 14 weeks, islet degeneration was more severe and widespread: β‐cell death was present in numerous islets at low level. Islet β‐cell numbers were reduced or absent (with associated reduction in insulin immunostaining) within the islets that now consisted predominantly of fibroblasts, collagen and mononuclear cells. Fibroproliferation consisting of smooth muscle actin‐α‐positive tissue was associated with mononuclear cell infiltration. Some fibrous scars were visible indicative of lost islets. Islet degeneration in obese ZF and ZDF rats was not accompanied by a reduction in β‐cell proliferation or in compensatory proliferation of β‐cell neogenic clusters. In the light of recent reports of adaptive and inflammation‐mediated degenerative changes in human non‐insulin dependent diabetes mellitus (NIDDM) islets, the hypertrophy/hyperplasia of β‐cells and islet degeneration involving infiltration by monocyte/macrophages in obese ZF and obese ZDF rats respectively offers substantial potential for elucidation of the processes involved.
Forgetfulness and older adults: concept analysis
Authors: Ballard Julianne
Published: April 2010

ballard j. (2010) Forgetfulness and older adults: concept analysis. Journal of Advanced Nursing 66(6), 1409–1419.

Title.  Forgetfulness and older adults: concept analysis.

Aim.  This paper is a report of an analysis of the concept of forgetfulness as it applies to older adults.

Background.  Perceived increases in forgetfulness cause much distress for older adults due to the stigma associated with memory loss and dementia. The difference between forgetfulness in a healthy ageing state and memory loss associated with cognitive impairment requires clarification for nurses involved in screening and caring for older adults.

Data sources.  Literature for this concept analysis was obtained by searches of CINAHL, EMBASE and Internurse covering the years 1962–2009, as well as gerontology textbooks.

Review methods.  The evolutionary method of Rodgers was the framework for the concept analysis.

Results.  As we age there is a slight increase in occasions of forgetfulness (particularly remembering to do things in the near future) that can be offset by limiting distractions and enhancing focus. This is contrasted with forgetfulness patterns, also more likely as we age, that are indicative of disease processes. Older adults’ awareness of their own forgetfulness has the potential to cause fear, embarrassment, anger and/or low self‐esteem.

Conclusion.  It is important to avoid labelling or dismissal of concerns related to forgetfulness in older adults. Further research, with an emphasis on the choice of assessment tool, is recommended to investigate the benefits of nurse‐led population screening for memory deficits in older adults. Nurses require training in assessment of memory and access to adequate referral pathways if abnormal results are uncovered.
Critical thinking dispositions among newly graduated nurses
Authors: Wangensteen Sigrid , Johansson Inger S. , Björkström Monica E , Nordström Gun
Published: April 2010

wangensteen s., johansson i.s., björkström m.e. & nordström g. (2010) Critical thinking dispositions among newly graduated nurses.Journal of Advanced Nursing 66(10), 2170–2181.

Aim. The aim of the study was to describe critical thinking dispositions among newly graduated nurses in Norway, and to study whether background data had any impact on critical thinking dispositions.

Background. Competence in critical thinking is one of the expectations of nursing education. Critical thinkers are described as well‐informed, inquisitive, open‐minded and orderly in complex matters. Critical thinking competence has thus been designated as an outcome for judging the quality of nursing education programmes and for the development of clinical judgement. The ability to think critically is also described as reducing the research–practice gap and fostering evidence‐based nursing.

Methods. A cross‐sectional descriptive study was performed. The data were collected between October 2006 and April 2007 using the California Critical Thinking Disposition Inventory. The response rate was 33% (n = 618). Pearson’s chi‐square tests were used to analyse the data.

Results. Nearly 80% of the respondents reported a positive disposition towards critical thinking. The highest mean score was on the Inquisitiveness subscale and the lowest on the Truth‐seeking subscale. A statistically significant higher proportion of nurses with high critical thinking scores were found among those older than 30 years, those with university education prior to nursing education, and those working in community health care.

Conclusion. Nurse leaders and nurse teachers should encourage and nurture critical thinking among newly graduated nurses and nursing students. The low Truth‐seeking scores found may be a result of traditional teaching strategies in nursing education and might indicate a need for more student‐active learning models.
Patients having haemodialysis: physical activity and associated factors
Authors: Li Mingzi , Li Liping , Fan Xiaozhi
Published: April 2010

li m., li l. & fan x. (2010) Patients having haemodialysis: physical activity and associated factors. Journal of Advanced Nursing 66(6), 1338–1345.

Title.  Patients having haemodialysis: physical activity and associated factors.

Aim.  This paper is a report of a study exploring the physical activity status of Beijing patients having haemodialysis and its associated factors.

Background.  Inactivity is widely regarded as a risk factor for the development and progression of chronic diseases. Patients having dialysis could obtain important health benefits by participating in a moderate amount of physical activity.

Methods.  A cross‐sectional survey using convenience sampling was conducted in 2008 at outpatient haemodialysis centres of two tertiary Peking University‐affiliated hospitals. Physical activity status and health status were assessed using the International Physical Activity Questionnaire and the medical outcomes study Short Form 36‐Item Questionnaire respectively.

Result.  The participants were 95 men and 92 women aged from 18 to 86 years (median 59 years). Transport‐related walking and household work were the main types of physical activity. Median of metabolic equivalent‐minutes/week was 1743·0 (0–13482·0); 26·7% of participants were inactive and 73·3% were minimally active or active. Factors associated with physical activity energy expenditure were age (ρ = −0·334 P < 0·001), serum albumin concentration (ρ = 0·155 P < 0·05), physical function (ρ = 0·469 P < 0·001) and physical component summary (ρ = 0·315 P < 0·001) scores on the Short Form 36‐Item Questionnaire.

Conclusion.  Advice on exercise is needed for patients having haemodialysis, especially for young patients. Individualized physical activity programmes are strongly recommended for patients having haemodialysis, according to their physical capacity.
Randomized controlled trials of interventions to change maladaptive illness beliefs in people with coronary heart disease: systematic review
Authors: Goulding Lucy , Furze Gill , Birks Yvonne
Published: April 2010

goulding l., furze g. & birks y. (2010) Randomized controlled trials of interventions to change maladaptive illness beliefs in people with coronary heart disease: systematic review. Journal of Advanced Nursing 66(5), 946–961.

Title.  Randomized controlled trials of interventions to change maladaptive illness beliefs in people with coronary heart disease: systematic review.

Aim.  This paper is a report of a systematic review of randomized controlled trials of interventions to change maladaptive illness beliefs in people with coronary heart disease, and was conducted to determine whether such interventions were effective in changing maladaptive beliefs, and to assess any consequent change in coping and outcome.

Background.  An increasing body of evidence suggests that faulty beliefs can lead to maladaptive behaviours and, in turn, to poor outcomes. However, the effectiveness of interventions to change such faulty illness beliefs in people with coronary heart disease is unknown.

Data sources.  Multiple data bases were searched using a systematic search strategy. In addition, reference lists of included papers were checked and key authors in the field contacted.

Review methods.  The systematic review included randomized controlled trials with adults of any age with a diagnosis of coronary heart disease and an intervention aimed at changing cardiac beliefs. The primary outcome measured was change in beliefs about coronary heart disease.

Results.  Thirteen trials met the inclusion criteria. Owing to the heterogeneity of these studies, quantitative synthesis was not practicable. Descriptive synthesis of the results suggested that cognitive behavioural and counselling/education interventions can be effective in changing beliefs. The effects of changing beliefs on behavioural, functional and psychological outcomes remain unclear.

Conclusion.  While some interventions may be effective in changing beliefs in people with coronary heart disease, the effect of these changes on outcome is not clear. Further high quality research is required before firmer guidance can be given to clinicians on the most effective method to dispel cardiac misconceptions.