bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersal dynamics of post‐larval blue crabs, Callinectes sapidus, within a wind‐driven estuary
Authors: REYNS NATHALIE B. , EGGLESTON DAVID B. , LUETTICH RICHARD A.
Published: May 2007

We examined how post‐larval blue crab (Callinectes sapidus) dispersal occurs within Pamlico Sound, NC, USA, a predominantly wind‐driven system. We sampled during multiple 24‐h periods over 2 years (2000–01) to relate the spatial distribution of post‐larvae in the water column with circulation patterns. A hydrodynamic model of the region was used to recreate dispersal trajectories and to assess potential transport mechanisms and pathways that link near‐inlet and across‐Sound nursery habitats. Most post‐larval blue crabs were collected in surface waters at night, and were consistently distributed within the north‐western region of Pamlico Sound. Particle‐tracking simulations suggested that dispersal from the inlets to across‐Sound nursery habitats only resulted from the combination of tidal and wind‐driven currents. Our simulation results further indicated that the northernmost inlet (Oregon Inlet) was the primary supplier of post‐larval blue crabs throughout the northern basin of Pamlico Sound, as crabs ingressing through Hatteras Inlet to the south were not retained within our study area. A dispersal pathway connecting Oregon Inlet and across‐Sound settlement habitats was evident from field observations. Collectively, our results indicate how multiple forcing agents, coupled with post‐larval vertical positioning within the water column, drive estuarine dispersal and connect spatially separated nursery habitats.
An individual‐based model for the direct conversion of otolith into somatic growth rates
Authors: HINRICHSEN H.‐H. , BUEHLER V. , CLEMMESEN C.
Published: May 2007

Otolith increment width and larval fish data (length and weight) were used to develop an individual‐based model (IBM) to describe daily resolved growth rates of North Sea herring (Clupea harengus) larvae (Autumn Spawners) caught during International Herring Larvae Surveys in the ICES area IVa from 1990 to 1998. The model combines sagittal otolith readings (core and individual increment measurements), larval standard length and weight data, and solves an over‐determined set of linear system equations for all parameters using the method of least square residuals. The model consists of a matrix, which describes the increment width formation of 119 larvae, a vector containing their length/weight measurements, and a vector describing residuals. The solution vector yields age‐dependent maximum somatic growth rates of herring larvae up to an age of 41 days with sizes ranging from 10 to 25 mm. The observed environmental temperature in which larvae dwelled was relatively uniform. Therefore, measured increment width was individually used to determine daily growth from any single larva in relation to their potential maximum growth under optimal feeding conditions. The results are discussed with respect to the spatial and temporal variability of larval occurrence. Finally, an analysis of error estimation of the larval growth characteristics is presented.
Diets of top predators indicate pelagic juvenile rockfish (Sebastesspp.) abundance in the California Current System
Authors: MILLS K. L. , LAIDIG T. , RALSTON S. , SYDEMAN W. J.
Published: May 2007

Diets of top predators may be useful indicators to the availability of forage fish in marine ecosystems. Juvenile rockfish (young‐of‐the‐yearSebastesspp.) compose a significant part of the diet for many predators in the central California Current, including chinook salmon (Oncorhynchus tshawytscha), and several species of marine birds and mammals. Herein, we develop annual indices of juvenile rockfish relative abundance by collating time series data sets on: (i) the proportion of rockfish in the diet of three species of seabirds breeding on Southeast Farallon Island (1975–2002); (ii) the number of rockfish in chinook salmon stomachs (1980–99); and (iii) the abundance of rockfish captured in scientific mid‐water trawl net surveys (1983–2002). We used Principal Component Analysis (PCA) to combine indices, and refer to these as ‘Multivariate Rockfish Indices’ (MRI). Combining time series verifies the patterns shown by each alone and provides a synoptic perspective on juvenile rockfish relative abundance. The diets of predators with the largest foraging ranges (Common Murre,Uria aalge) and chinook salmon co‐varied strongly with the net samples, and appear to be the best indicators. The salmon also sampled species ofSebastesnot caught in the nets. The MRI reveals interannual variability in juvenile rockfish abundance, a substantial decline in abundance in the 1990s, and a partial recovery in the early 2000s. Predator‐based sampling is a cost‐effective enhancement of scientific net sampling.
Benthic organic carbon influences denitrification in streams with high nitrate concentration
Authors: ARANGO CLAY P. , TANK JENNIFER L. , SCHALLER JAMIE L. , ROYER TODD V. , BERNOT MELODY J. , DAVID MARK B.
Published: May 2007

1. Anthropogenic activities have increased reactive nitrogen availability, and now many streams carry large nitrate loads to coastal ecosystems. Denitrification is potentially an important nitrogen sink, but few studies have investigated the influence of benthic organic carbon on denitrification in nitrate‐rich streams.

2. Using the acetylene‐block assay, we measured denitrification rates associated with benthic substrata having different proportions of organic matter in agricultural streams in two states in the mid‐west of the U.S.A., Illinois and Michigan.

3. In Illinois, benthic organic matter varied little between seasons (5.9–7.0% of stream sediment), but nitrate concentrations were high in summer (>10 mg N L−1) and low (<0.5 mg N L−1) in autumn. Across all seasons and streams, the rate of denitrification ranged from 0.01 to 4.77 μg N g−1 DM h−1 and was positively related to stream‐water nitrate concentration. Within each stream, denitrification was positively related to benthic organic matter only when nitrate concentration exceeded published half‐saturation constants.

4. In Michigan, streams had high nitrate concentrations and diverse benthic substrata which varied from 0.7 to 72.7% organic matter. Denitrification rate ranged from 0.12 to 11.06 μg N g−1 DM h−1 and was positively related to the proportion of organic matter in each substratum.

5. Taken together, these results indicate that benthic organic carbon may play an important role in stream nitrogen cycling by stimulating denitrification when nitrate concentrations are high.
Trout affect the density, activity and feeding of a larval plethodontid salamander
Authors: BARR GARRETT E. , BABBITT KIMBERLY J.
Published: May 2007

1. Ecologists have struggled to describe general patterns in the impacts of predators on stream prey, particularly at large, realistic spatial and temporal scales. Among the confounding variables in many systems is the presence of multiple predators whose interactions can be complex and unpredictable.

2. We studied the interactions between brook trout (Salvelinus fontinalis) and larval two‐lined salamanders (Eurycea bislineata), two dominant vertebrate predators in New England stream systems, by examining patterns of two‐lined salamander abundance in stream reaches above and below waterfalls that are barriers to fish dispersal, by measuring the effects of trout on salamander density and activity using a large‐scale manipulation of brook trout presence, and by conducting a small‐scale laboratory experiment to study how brook trout and larval two‐lined salamanders affect each other's prey consumption.

3. We captured more salamanders above waterfalls, in the absence of trout, than below waterfalls where trout were present. Salamander density and daytime activity decreased following trout addition to streams, and salamander activity shifted from aperiodic to more nocturnal with fish. Analysis of stomach contents from our laboratory experiment revealed that salamanders eat fewer prey with trout, but trout eat more prey in the presence of salamanders.

4. We suggest that as predators in streams, salamanders can influence invertebrate prey communities both directly and through density‐ and trait‐mediated interactions with other predators.
Predicting local biological characteristics in streams: a comparison of landscape classifications
Authors: PYNE MATTHEW I. , RADER RUSSELL B. , CHRISTENSEN WILLIAM F.
Published: May 2007

1. Landscape classifications group tracts of land based on similar physico‐chemical attributes that may affect the biological characteristics of streams at local scales. We tested the ability of five landscape models to account for variation in algal and macroinvertebrate biomass, brook trout (Salvelinus fontinalis) growth and macroinvertebrate community composition from 132 riffles in 15 catchments in the Big Horn Mountains, Wyoming.

2. A model created by the U.S. Forest Service (FS) combined catchment and ecoregion approaches to classify the landscape. Our model used digital elevations to create a landscape classification for streams (DEM). The last three models were based on: (1) standard ecoregions (Ecoregion), (2) the type of underlying bedrock (Geology) and (3) the geographical distance between sites (Site Proximity model).

3. Overall, the Ecoregion and Geology models performed better than the two catchment models (FS and DEM) in predicting local biological characteristics. The Geology model was best at predicting differences in algal and macroinvertebrate biomass, the Site Proximity and Ecoregion models were best at predicting patterns of similarity in macroinvertebrate community composition, and the Site Proximity, Ecoregion, Geology, and FS models, in order from best to worst, accounted for significant variation in brook trout growth. The Site Proximity model performed well because of the effects of spatial autocorrelation. The DEM was consistently one of the worst models at predicting local biological characteristics because it failed to include important attributes (e.g. dominant geology). Calcareous geology was positively associated with greater macroinvertebrate biomass and faster brook trout growth, but it was inversely related to algal biomass.

4. None of the models accounted for a large amount of variation in local biological characteristics. Single‐scale, landscape classifications may never accurately predict variation in local biological characteristics because: (1) landscapes show a high degree of spatial heterogeneity, (2) local effects are stronger than landscape attributes and (3) there are too many intervening levels between landscape and local scales in the nested hierarchy of streams. However, landscape classifications did account for significant variation in biological characteristics. Thus, they would be a valuable management tool as part of a multi‐scale, hierarchical technique for classifying stream ecosystems.
Factors influencing the variability of pigments in the surface sediments of mountain lakes
Authors: BUCHACA TERESA , CATALAN JORDI
Published: May 2007

1. Surface sediment biofilm samples from 82 Pyrenean lakes were analysed for marker pigment composition using high performance liquid chromatography (HPLC).

2. Variability in the pigment composition among lakes was investigated by multivariate statistical analyses using a large data set of factors describing lake chemical, physical, morphological and catchment characteristics.

3. Due to the widely varying light penetration in the lakes, the most significant gradient of pigment composition extended from a benthic to a planktonic signal. The most important pigments in the gradient were alloxanthin (cryptophytes marker pigment, planktonic signal) and diatoxanthin (diatoms marker pigment, benthic signal). The molar ratio between these two marker pigments was positively correlated with lake depth.

4. Chlorophyll‐a preservation was found to be positively related to light penetration and the development of an autothrophic biofilm on the surface sediment and negatively related to decreasing pH and the percentage of alpine meadows in the lake catchments.

5. Zooplankton marker pigments in the surface sediment, including grazing by‐products (e.g. phaeophorbides) and carotenoids (astaxanthin, canthaxanthin, echinenone) incorporated into their tissues, were correlated with the areal abundance of zooplankton.

6. Marker pigments for photosynthetic bacteria, BChl‐e and okenone, were found mainly in relatively shallow lakes with large catchments that are forested, probably because of their higher loading of allochthonous organic matter.

7. The evaluation of a preservation index (Chl‐a expressed as a percentage of a‐phorbins) and the alloxanthin/diatoxanthin ratios throughout the sediment record of mountain lakes can provide evidence of historical changes in the relative importance of planktonic versus benthic primary production and might ultimately be interpreted in terms of climatic or environmental changes.
Users’ views of prison health services: a qualitative study
Authors: Condon Louise , Hek Gill , Harris Francesca , Powell Jane , Kemple Terry , Price Sally
Published: May 2007

Title. Users’ views of prison health services: a qualitative study.

Aim.  This paper is a report of a study of the views of prisoners about health services provided in prisons.

Background.  Prison provides an opportunity for a ‘hard to reach’ group to access health services, primarily those provided by nurses. Prisoners typically have high health and social needs, but the views and experiences of prisoners about health services in prison have not been widely researched.

Method.  Semi‐structured interviews were carried out with 111 prisoners in purposively selected 12 prisons in England in 2005. Interviews covered both prisoners’ views of health services and their own ways of caring for their health in prison. Interviews were analysed to develop a conceptual framework and identify dominant themes.

Findings.  Prisoners considered health services part of a personal prison journey, which began at imprisonment and ended on release. For those who did not access health services outside prison, imprisonment improved access to both mental and physical health services. Prisoners identified accessing services, including those provided by nurses, confidentiality, being seen as a ‘legitimate’ patient and living with a chronic condition as problems within the prison healthcare system. At all points along the prison healthcare journey, the prison regime could conflict with optimal health care.

Conclusion.  Lack of autonomy is a major obstacle to ensuring that prisoners’ health needs are fully met. Their views should be considered when planning, organizing and delivering prison health services. Further research is needed to examine how nurses can ensure a smooth journey through health care for prisoners.
The attitudes of Chinese family caregivers of older people with dementia towards life sustaining treatments
Authors: Kwok Timothy , Twinn Sheila , Yan Elsie
Published: May 2007

Title. The attitudes of Chinese family caregivers of older people with dementia towards life sustaining treatments

Aim.  This paper is a report of a study to examine attitudes towards life‐sustaining treatment in family caregivers of older Chinese people with dementia.

Background.  Deferring decisions about life‐sustaining treatments to surrogate decision‐makers is common among older people with dementia. However, surrogate decision‐makers frequently lack knowledge about disadvantages and benefits of treatments and do not understand the principles of surrogate decision‐making.

Method.  A total of 51 Chinese family caregivers were interviewed during 2003 and 2004. The interview included an assessment of their knowledge about cardiopulmonary resuscitation and tube feeding, a questionnaire to assess their anticipated decisions for four treatments (cardiopulmonary resuscitation, artificial ventilation, tube feeding and antibiotic administration) if the older relative suffered critical illness or irreversible coma, and their comfort and certainty in making such decisions.

Findings.  Family caregivers displayed poor knowledge about life‐sustaining treatments, with 30 (59%) and 13 (26%) unable to name any feature of cardiopulmonary resuscitation and tube feeding, respectively. Most relied on their own views in decision‐making rather than on what they thought their relative would have wanted. Most family caregivers were reluctant to forgo treatments. Nursing home residence predicted family caregivers’ willingness to forgo artificial ventilation for critical illness. Financial burden predicted inclination to forgo antibiotics for critical illness and irreversible coma, as well as tube feeding in irreversible coma.

Conclusion.  More dialogue and education are needed about end of life issues in the early phase of dementia. Nurses should be aware of the cultural implications of surrogate decision‐making for Chinese family caregivers.
Home visiting programme for older people with health problems: process evaluation
Authors: Nicolaides‐Bouman Ans , Van Rossum Erik , Habets Herbert , Kempen Gertrudis I.J.M. , Knipschild Paul
Published: May 2007

Title.  Home visiting programme for older people with health problems: process evaluation

Aim.  This paper is a report of a process evaluation of the content, patient compliance and participant experiences of a home visiting programme for older people with self‐reported health problems.

Background.  Systematic home visits by nurses to older people are a public health strategy to improve their functional abilities and prevent institutionalization. Evidence of the usefulness of these visits is conflicting, partly due to a lack of information on the intervention process in these programmes.

Method.  One hundred and sixty people (aged 70–84 years) participated in the programme and were visited eight times during an 18‐month period (February 2003–October 2004) by experienced home nurses. The nurses recorded key elements of each visit on standard forms: topics discussed, interventions regarding health problems and risks, and compliance with these interventions. Participants’ and nurses’ opinions on the visits were obtained through interviews at the end of the programme.

Findings.  Nearly 80% of the group received the complete programme. Problems were detected in nearly all visits, mainly regarding social and psychological functioning, circulatory and musculoskeletal problems, and vision or hearing impairment. On average, ten problems and 11 interventions were recorded per participant. Nearly 40% of interventions related to referrals, 45% to advice and 17% consisted of information‐giving. The compliance rate was 65% for referrals and 58% for advice. Both nurses and participants were positive about the programme.

Conclusion.  A health visiting programme, performed by home nurses, is feasible and appreciated by frail elders. The latter seem to be a relevant target population in view of the many and varied problems detected.
Family interviews as a method for family research
Authors: Eggenberger Sandra K. , Nelms Tommie P.
Published: May 2007

Title. Family interviews as a method for family research

Aim.  This paper is a description of the experience of conducting family interviews in a study to come to understand from families their experience of the hospitalization of a critically ill family member.

Background.  Traditional family research has been done quantitatively, with a focus on the needs of individual family members rather than the family as a whole. The limited amount of qualitative family research has been done primarily by interviewing individual family members rather than the family as a group.

Method.  The original study was conducted within a framework of phenomenology and 11 families, for a total of 41 individuals, were interviewed about their experiences. Family groups from two to seven members, some including adolescents and young adults, participated in semi‐structured interviews.

Findings.  Findings revealed that gathering families together, even early in the critical illness experience, is not only feasible but beneficial for them and opens the door to dialogues that have a therapeutic effect on the family and help them manage the critical illness experience. Although daunting and challenging, family interviews are feasible and provide rich family‐level data that contribute knowledge to family science and family caring. Strategies for family recruitment, conduct of family interviews and family‐level data analysis are presented.

Conclusion.  Families want to tell their stories and clearly have a need for nurses to develop relationships with them while caring for their ill loved ones. Family interviews both affirm the family and give nurses greater understanding of family issues, concerns and meanings.
Distinguishing between task and contextual performance for nurses: development of a job performance scale
Authors: Greenslade Jaimi H. , Jimmieson Nerina L.
Published: May 2007

Title. Distinguishing between task and contextual performance for nurses: development of a job performance scale

Aim.  This paper is a report of a development and validation of a new job performance scale based on an established job performance model.

Background.  Previous measures of nursing quality are atheoretical and fail to incorporate the complete range of behaviours performed. Thus, an up‐to‐date measure of job performance is required for assessing nursing quality.

Methods.  Test construction involved systematic generation of test items using focus groups, a literature review, and an expert review of test items. A pilot study was conducted to determine the multidimensional nature of the taxonomy and its psychometric properties. All data were collected in 2005.

Findings.  The final version of the nursing performance taxonomy included 41 behaviours across eight dimensions of job performance. Results from preliminary psychometric investigations suggest that the nursing performance scale has good internal consistency, good convergent validity and good criterion validity.

Conclusion.  The findings give preliminary support for a new job performance scale as a reliable and valid tool for assessing nursing quality. However, further research using a larger sample and nurses from a broader geographical region is required to cross‐validate the measure. This scale may be used to guide hospital managers regarding the quality of nursing care within units and to guide future research in the area.
Concept analysis: the importance of differentiating the ontological focus
Authors: Duncan Craig , Cloutier Julie Duff , Bailey P.H.
Published: May 2007

Title. Concept analysis: the importance of differentiating the ontological focus

Aim.  The aim of this paper is to clarify the philosophical underpinnings of concepts and concept analysis and the implications of their use through the lens of particular ontological perspectives.

Background.  Information on the philosophical foundations of concepts from an ontological and epistemological perspective is not readily identifiable in the international literature. Although some authors have made reference to the ontological perspectives of specific concept analysis processes, none have addressed the implications of the realist or relativist perspective in relation either to the analysis process or the implications of a particular ontological perspective on the meaning and utility of a specific concept.

Method.  We describe the evolution of concept analysis and influence of ontological paradigms on specific analysis methods. Using an historical review of concept development within nursing thought, we decode the language of concepts and processes of concept analysis, outline the importance of the ontological foundation of concept development, and describe the impact of concept use.

Discussion.  The nursing literature is dominated by concepts created from a realist perspective. Although recent nurse–authors have introduced evidence‐based data to facilitate the development of a number of concepts, they have held fast to the perception that the ‘best’, most adequate or mature concepts transcend context.

Conclusion.  The theoretical shift from context‐bound empirical analysis of concepts belies the complexity of nurses’ work. Concepts are unapologetically context‐bound. A concept that transcends context (based on realist ontology) will remain the same even when the context of praxis changes limiting its utility.
Using an interactive voice response system to improve patient safety following hospital discharge
Authors: Forster Alan J. , Van Walraven Carl
Published: May 2007

Background  Patients often experience complications when transitioning from hospital to home. These complications are frequently related to poor monitoring. An interactive voice response system (IVRS) could improve post‐discharge monitoring.

Objective  To determine the feasibility and utility of an IVRS to monitor patients following hospital discharge.

Design  Prospective cohort study at an academic health sciences centre.

Patients  Consecutive internal medicine patients who had a touch‐tone telephone, spoke English, had no cognitive impairments and were discharged home.

Measurements  Feasibility was defined as the proportion of patients reached by the IVRS and the proportion completing an IVRS‐based survey. Utility was defined as the percentage of patients whose outcomes could have been changed by the IVRS.

Methods  We programmed the IVRS to call patients and administer a simple survey 48 hours after discharge. The survey’s objective was to identify all patients with new health problems. Such patients were telephoned by a nurse to clarify and address the problem.

Results  We enrolled 77 patients who were predominantly male (68%), elderly (median age 65 years) and chronically ill (median number of co‐morbidities = 3). The IVRS reached 45 of the 77 patients (58.4%). Forty patients (51.9%) answered all questions on the survey. Twenty patients (26%, 95% CI 17%−37%) indicated new or worsening symptoms, problems with their medications, or requested to talk to the clinic nurse. For 10 patients (13%, 95% CI 7%−22%), the IVRS could have made a difference in their outcome.

Conclusion  Using an IVRS, we were able to identify several important new health concerns arising following hospital discharge. Subtle changes could increase the feasibility and utility of IVRS technology in improving post‐discharge outcomes.
Pharmacokinetics of oral doxycycline and concentrations in body fluids and bronchoalveolar cells of foals
Authors: WOMBLE A. , GIGUÈRE S. , LEE E. A.
Published: May 2007

The objective of this study was to determine the disposition of orally administered doxycycline in foals. Six healthy 4‐ to 8‐week‐old foals were used. Doxycycline was administered to each foal via the intragastric (IG) route at dosages of 10 and 20 mg/kg, in a cross‐over design. After the first 10 mg/kg dose, five additional doses were administered at 12‐h intervals. A microbiological assay was used to measure doxycycline activity in serum, urine, peritoneal fluid, synovial fluid, cerebrospinal (CSF), pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. Following administration at 10 mg/kg, mean ± SD time to peak serum doxycycline activity (tmax) was 3.0 ± 1.2 h, maximum serum activity (Cmax) was 2.54 ± 0.27 μg/mL, and terminal half‐life (t1/2) was 8.5 ± 2.8 h. Administration at a dose of 20 mg/kg resulted in a significantly longertmax(5.5 ± 1.8 h) as well as a tendency toward higherCmax(2.89 ± 0.33 μg/mL) and longert1/2(11.9 ± 2.6 h). After multiple IG doses, doxycycline activity in CSF was significantly lower than concurrent serum activity, whereas peritoneal fluid, synovial fluid, and BAL cell doxycycline activity was similar to concurrent serum activity. Doxycycline activity in urine and PELF was significantly higher than that found at other sites. Oral administration at a dosage of 10 mg/kg every 12 h would maintain serum, PELF, and BAL cell activity above the minimum inhibitory concentrations ofRhodococcus equi,β‐hemolytic streptococci, and other susceptible bacterial pathogens for the entire dosing interval.
Non‐uniform assembly of the Bacillus anthracis exosporium and a bottle cap model for spore germination and outgrowth
Authors: Steichen Christopher T. , Kearney John F. , Turnbough Charles L.
Published: May 2007

Spores of Bacillus anthracis are enclosed by an exosporium composed of a basal layer and an external hair‐like nap. The nap is formed by a collagen‐like glycoprotein called BclA, while the basal layer contains many different proteins, one of which is a spore‐specific alanine racemase (Alr). In this study, we employed fluorescence microscopy and a fluorescently labelled anti‐Alr monoclonal antibody (mAb) to examine the distribution of Alr within the exosporium. Binding of the mAb occurred over approximately three‐quarters of the exosporium but not in a cap‐like region at one end of the spore, indicating the absence or inaccessibility of Alr in this region. We also determined that the cap‐like region, or cap, corresponds to the first part of the exosporium assembled within the mother cell during sporulation and the only part of the exosporium assembled in a ΔexsY mutant strain of B. anthracis. Our results provide the first direct evidence that exosporium assembly is a non‐uniform process and suggest that exosporium formation is discontinuous. Finally, we demonstrated that during spore germination and outgrowth, the outgrowing cell always escapes from its exosporium shell by popping through the cap, suggesting that the cap is designed to facilitate the emergence of the outgrowing cell.
Cell envelope stress induced by the bacteriocin Lcn972 is sensed by the lactococcal two‐component system CesSR
Authors: Martínez Beatriz , Zomer Aldert L. , Rodríguez Ana , Kok Jan , Kuipers Oscar P.
Published: May 2007

The non‐pore‐forming bacteriocin lactococcin 972 (Lcn972) inhibits the synthesis of peptidoglycan at the septum in Lactococcus lactis. In this work, the genome‐wide response of L. lactis MG1614 to Lcn972 was analysed by DNA microarrays. We found 26 genes to be significantly upregulated. Most of these encode membrane proteins of unknown function and the two‐component system (TCS) CesSR (formerly known as TCS‐D). CesSR orchestrates the response of L. lactis to Lcn972. None of the genes upregulated in L. lactis MG1614 were induced by Lcn972 in L. lactisΔcesR. In silico analysis of the promoter regions of the upregulated genes revealed a novel conserved 16 bp palindromic sequence at positions −73/−72 or −46 relative to the putative transcriptional start sites. Point mutations and deletion of this CesR box abolished regulation. Purified His‐tagged CesR interacts in electrophoretic mobility shift assays with several promoters carrying the CesR box. The CesR box is also present in other Gram‐positive cocci, upstream of genes involved in cell envelope stress. CesSR was strongly induced by lipid II‐interacting cationic polypeptides and disruption of cesR increased susceptibility to these antimicrobials. We propose here that CesSR of L. lactis controls the immediate response to cell envelope stress in this organism.
Mutualism and pathogenesis in Xenorhabdus and Photorhabdus: two roads to the same destination
Authors: Goodrich‐Blair Heidi , Clarke David J.
Published: May 2007

Photorhabdus and Xenorhabdus bacteria colonize the intestines of the infective soil‐dwelling stage of entomophagous nematodes, Heterorhabditis and Steinernema, respectively. These nematodes infect susceptible insect larvae and release the bacteria into the insect blood. The bacteria kill the insect larvae and convert the cadaver into a food source suitable for nematode growth and development. After several rounds of reproduction the nematodes are recolonized by the bacteria before emerging from the insect cadaver into the soil to search for a new host. Photorhabdus and Xenorhabdus bacteria therefore engage in both pathogenic and mutualistic interactions with different invertebrate hosts as obligate components of their life cycle. In this review we aim to describe current knowledge of the molecular mechanisms utilized by Photorhabdus and Xenorhabdus to control their host‐dependent interactions. Recent work has established that there is a trade‐off between pathogenicity and mutualism in both these species of bacteria suggesting that the transition between these interactions must be under regulatory control. Despite the superficial similarity between the life cycles of these bacteria, it is now apparent that the molecular components of the regulatory networks controlling pathogenicity and mutualism in Photorhabdus and Xenorhabdus are very different.
MutS deficiency and activity of the error‐prone DNA polymerase IV are crucial for determining mucA as the main target for mucoid conversion in Pseudomonas aeruginosa
Authors: Moyano Alejandro J. , Luján Adela M. , Argaraña Carlos E. , Smania Andrea M.
Published: May 2007

Pseudomonas aeruginosa colonizes the respiratory tract of cystic fibrosis (CF) patients, where mutators along with mucoid variants emerge leading to chronic infection. Mucoid conversion generally involves mutations inactivating the mucA gene. This study correlates the frequency and nature of mucA mutations with the activity of factors determining the mutation rate, such as MutS and polymerase IV (Pol IV). Results show that: (i) the emergence frequency of mucoid variants was higher in isolates arising from mutS populations compared with the wild‐type strain; (ii) in both strains mucoid conversion occurred mainly by mucA mutations; (iii) however, the mutator strain harboured mostly mucA22 (a common allele in CF isolates), while the wild type showed a wider spectrum of mucA mutations with low incidence of mucA22; (iv) disruption of dinB in the wild‐type and mutS strains decreased drastically the emergence frequency of mucoid variants; (v) furthermore, the incidence of mucA mutations diminished in the mutS dinB double mutant strain which consisted only in mucA22; (vi) finally, the mucoid isolates obtained from the dinB strain showed an unexpected absence of mucA mutations. Taken together results demonstrate the implication of both MutS and Pol IV in determining mucA as the main target for conversion to mucoidy.
Perturbations to engulfment trigger a degradative response that prevents cell–cell signalling during sporulation in Bacillus subtilis
Authors: Doan Thierry , Rudner David Z.
Published: May 2007

During sporulation in Bacillus subtilis, the mother cell membranes migrate around the forespore in a phagocytic‐like process called engulfment. Developmental gene expression requires the successful completion of this key morphological event. Here we show that perturbations to engulfment block the accumulation of proteins secreted into the space between the mother cell and forespore membranes. Our data support a model in which engulfment defects cause the proteolytic clearance of these secreted proteins. Importantly, we show that this degradative response is reversible; once proper engulfment is restored, secreted proteins again accumulate. In particular, we have found that the forespore signalling protein SpoIVB fails to accumulate when engulfment is impaired and, as a result, late mother cell gene expression under the control of σK is blocked. If engulfment is restored, SpoIVB accumulates and cell–cell signalling resumes. Thus, this degradative pathway functions like a developmental checkpoint ensuring that mother cell gene expression does not commence unless morphogenesis proceeds normally.
The yeast ammonium transport protein Mep2 and its positive regulator, the Npr1 kinase, play an important role in normal and pseudohyphal growth on various nitrogen media through retrieval of excreted ammonium
Authors: Boeckstaens Mélanie , André Bruno , Marini Anna Maria
Published: May 2007

Three ammonium transport systems of the Mep/Amt/Rh superfamily contribute to ammonium uptake for use as a nitrogen source in Saccharomyces cerevisiae. A specific sensor role has further been proposed for Mep2 in the stimulation of pseudohyphal development during ammonium limitation. Optimal ammonium transport by the Mep proteins requires the Npr1 kinase, a potential target of the target‐of‐rapamycin signalling pathway. We show here that the growth impairment of cells lacking Npr1 on many nitrogen sources is shared by cells deprived of the three Mep proteins and is a consequence of deficient ammonium retrieval. Expression of a newly isolated Npr1‐independent and hyperactive Mep2 in cells lacking Npr1 and/or the Mep proteins restores growth on low ammonium but also on other nitrogen sources. This hyperactive Mep2 variant efficiently counteracts ammonium excretion. Hence, ammonium uptake activity plays an important role in compensating for leakage of catabolic ammonium. Our data also reveal that the requirement of Npr1 for ammonium‐induced pseudohyphal growth is an indirect consequence of its necessity for Mep2‐mediated ammonium transport. Finally, we show that Mep2 participates, through ammonium leakage compensation, in pseudohyphal growth induced by amino acid starvation. This argues further in favour of tight coupling of Mep2 transport and sensor functions.
Remyelination can be extensive in multiple sclerosis despite a long disease course
Authors: Patani R. , Balaratnam M. , Vora A. , Reynolds R.
Published: May 2007

Experimental studies using models of multiple sclerosis (MS) indicate that rapid and extensive remyelination of inflammatory demyelinated lesions is not only possible, but is the normal situation. The presence of completely remyelinated MS lesions has been noted in numerous studies and routine limited sampling of post mortem MS material suggests that remyelination may be extensive in the early stages but eventually fails. However, visual macroscopic guided sampling tends to be biased towards chronic demyelinated lesions. Here we have extensively sampled cerebral tissue from two MS cases to investigate the true extent of remyelination. Sections were cut from 185 cerebral tissue blocks and stained with haematoxylin and eosin (H&E), luxol fast blue and cresyl fast violet (LFB/CFV) and anti‐myelin oligodendrocyte glycoprotein, human leucocyte antigen‐DR (HLA‐DR) and 200 kDa neurofilament protein antibodies. Demyelinated areas were identified in 141 blocks, comprising both white matter (WMLs) and/or grey matter lesions. In total, 168 WMLs were identified, 22% of which were shadow plaques, 73% were partially remyelinated and only 5% were completely demyelinated. The average extent of lesion remyelination for all WMLs investigated was 47%. Increased density of HLA‐DR+ macrophages and microglia at the lesion border correlated significantly with more extensive remyelination. Results from this study of two patients with long standing disease suggest that remyelination in MS may be more extensive than previously thought.
Fcγ Receptor Polymorphisms are not Associated with Autoimmune Addison's Disease
Authors: Wolff A. S. B. , Myhr K.‐M. , Vedeler C. A. , Husebye E. S.
Published: May 2007

Polymorphisms in the low‐affinity Fcγ receptors (FcγR) modulate their capacity to bind IgG and the subsequent immune response. Different FcγR polymorphisms have been reported to be associated with susceptibility and severity of various autoimmune diseases. We wanted to investigate associations between FcγR polymorphisms and autoimmune primary adrenal failure (Addison's disease). We have genotyped 149 patients with Addison's disease and 89 healthy controls for common polymorphisms in the genes coding for FcγRIIa, FcγRIIIa and FcγRIIIb using polymerase chain reaction. Patients with Addison's disease and controls showed no differences in genotype distributions of FcγRIIa, FcγRIIIa and FcγRIIIb. The results indicate that different FcγR polymorphisms do not have an impact on immune responses involved in the development of autoimmune Addison's disease.
The chloroplast HSP70B‐CDJ2‐CGE1 chaperones catalyse assembly and disassembly of VIPP1 oligomers in Chlamydomonas
Authors: Liu Cuimin , Willmund Felix , Golecki Jochen R. , Cacace Sabrina , Heß Barbara , Markert Christine , Schroda Michael
Published: April 2007

The vesicle‐inducing protein in plastids (VIPP1) is essential for the biogenesis of thylakoid membranes in cyanobacteria and plants. VIPP1 and its bacterial ancestor PspA form large homo‐oligomeric rings of >1 MDa. We recently demonstrated that VIPP1 interacts with the chloroplast J‐domain co‐chaperone CDJ2 and its chaperone partner HSP70B, and hypothesized that the chaperones might be involved in the assembly and/or disassembly of VIPP1 oligomers. To test this hypothesis, we analysed the composition of VIPP1/chaperone complexes in Chlamydomonas reinhardtii cell extracts and monitored effects of the chaperones on VIPP1 assembly states in vitro. We found that CGE1, the chloroplast GrpE homologue, is also part of complexes with HSP70B, CDJ2 and VIPP1. We observed that CDJ2‐VIPP1 accumulated as low‐ and high‐molecular‐weight complexes in ATP‐depleted cell extracts, but as intermediate‐size complexes in extracts supplemented with ATP. This was consistent with a role for the chaperones in VIPP1 assembly and disassembly. Using purified proteins, we could demonstrate that the chaperones indeed facilitated both the assembly and disassembly of VIPP1 oligomers. Electron microscopy studies revealed that, in contrast to PspA, VIPP1 rings assembled into rod‐shaped supercomplexes that were morphologically similar to microtubule‐like structures observed earlier in various plastid types. VIPP1 rods, too, were disassembled by the chaperones, and chaperone‐mediated rod disassembly also occurred when VIPP1 lacked an approximately 30‐aa C‐terminal extension present in VIPP1 homologues but absent in PspA. By regulating the assembly state of VIPP1, the chloroplast HSP70 chaperone system may play an important role in the maintenance/biogenesis of thylakoid membranes.
Identification and functional characterization of cation–chloride cotransporters in plants
Authors: Colmenero‐Flores José M. , Martínez Germán , Gamba Gerardo , Vázquez Norma , Iglesias Domingo J. , Brumós Javier , Talón Manuel
Published: April 2007

Chloride (Cl−) is an essential nutrient and one of the most abundant inorganic anions in plant tissues. We have cloned an Arabidopsis thaliana cDNA encoding for a member of the cation–Cl− cotransporter (CCC) family. Deduced plant CCC proteins are highly conserved, and phylogenetic analyses revealed their relationships to the sub‐family of animal K+:Cl− cotransporters. In Xenopus laevis oocytes, the A. thaliana CCC protein (At CCC) catalysed the co‐ordinated symport of K+, Na+ and Cl−, and this transport activity was inhibited by the ‘loop’ diuretic bumetanide, a specific inhibitor of vertebrate Na+:K+:Cl− cotransporters, indicating that At CCC encodes for a bona fide Na+:K+:Cl− cotransporter. Analysis of At CCC promoter‐β‐glucuronidase transgenic Arabidopsis plants revealed preferential expression in the root and shoot vasculature at the xylem/symplast boundary, root tips, trichomes, leaf hydathodes, leaf stipules and anthers. Plants homozygous for two independent T‐DNA insertions in the CCC gene exhibited shorter organs such as inflorescence stems, roots, leaves and siliques. The elongation zone of the inflorescence stem of ccc plants often necrosed during bolt emergence, while seed production was strongly impaired. In addition, ccc plants exhibited defective Cl− homeostasis under high salinity, as they accumulated higher and lower Cl− amounts in shoots and roots, respectively, than the treated wild type, suggesting At CCC involvement in long‐distance Cl− transport. Compelling evidence is provided on the occurrence of cation–chloride cotransporters in the plant kingdom and their significant role in major plant developmental processes and Cl− homeostasis.
Apparent low absorbers of cyclosporine microemulsion have higher requirements for tacrolimus in renal transplantation
Authors: House Andrew A. , Elmestiri Mostafa , Denesyk Kathy , Luke Patrick P. , Muirhead Norman , Rehman Faisal , Boudville Neil , Jevnikar Anthony M.
Published: April 2007

Abstract:  Bioavailability and exposure of cyclosporine microemulsion and tacrolimus in renal transplantation are governed by many complex factors. Failure to achieve therapeutic two‐h post‐dose (C2) levels despite adequate doses of cyclosporine (“low absorbers”) may merit conversion to tacrolimus. We compared tacrolimus dose requirements in “low absorbers” (n = 15) with a random control group of de novo tacrolimus patients (n = 14). Low absorbers failed to reach target C2 despite increasing dose from 10.1 to 16.2 mg/kg/d. At conversion the mean C2 was 969 ng/mL (95% CI: 684–1255; target 1700 ng/mL). Low absorbers tended to be younger, heavier, and diabetic. Despite a similar initial tacrolimus dose (0.17–0.18 mg/kg/d), low absorbers required a much higher daily dose to achieve target; 0.25 vs. 0.16 mg/kg/d (p = 0.016). Furthermore, daily maintenance tacrolimus remained much higher in low absorbers at three wk (0.22 vs. 0.13 mg/kg/d, p = 0.012). Although not statistically significant, this group experienced an acute rejection rate of 33%, compared with 21% in the control group. Patients treated with cyclosporine as initial immunosuppression who fail to reach target C2 levels in a timely fashion are at risk for impaired bioavailability of tacrolimus. Based on our data, a starting dose of 0.25 mg/kg/d in divided doses may be warranted for low absorbers converting to tacrolimus; however, we encourage larger studies with formal pharmacokinetic analysis in this population.
Preliminary analysis of a KIR haplotype estimation algorithm: a simulation study
Authors: Gourraud P. A. , Gagne K. , Bignon J. D. , Cambon‐Thomsen A. , Middleton D.
Published: April 2007

The analysis of Killer cell immunoglobulin‐like receptors (KIRs) in terms of haplotypes have only been done through genotyping numerous and selected families. Consequently and schematically, KIR haplotypes have been roughly described by two groups (A and B) based on their gene contents. No further KIR adapted methods have been applied to the estimation of haplotype frequencies using unrelated data. We propose here a maximum likelihood (ML) estimation of KIR haplotype frequencies. ML estimation was developed as an extension of those successfully applied to human leukocyte antigen (HLA) data including the handling of missing values and HLA nomenclature. It has been implemented using an adapted Expectation Masimisation algorithm. KIR types on 11 loci in more than 40 Irish families were used to validate the method in a simulation study. Estimated haplotype frequencies are compared to the phase known. Various allele or gene frequency estimation methods were also compared. We demonstrated the interest and reliability of the haplotype method and underline the effect of the sample size on the quality of the estimation. The ML haplotype method also provides by collapsing more accurate estimation of allele or gene frequencies in population. Such an algorithm opens new perspectives in the analysis of KIR genotypes. Large sample size studies are required using phase‐known data and/or simulations. It would allow a genotype‐based approach to explore the KIR gene haplotype diversity. The haplotype frequencies may be used to compare populations.