bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect and potential ecological significance of the interaction of humic acids with two aquatic extracellular proteases
Authors: DUDLEY RICHARD J. , CHURCHILL PERRY F.
Published: May 2006

1. The effects of humic acids and fulvic acids on an extracellular serine and metalloprotease purified from a strain of Aeromonas hydrophila isolated from a freshwater wetland were examined. The serine protease was inhibited by humic acids at pH and humic acid concentrations found naturally in the wetland where this strain of A. hydrophila was isolated. The metalloprotease was not inhibited by humic acids at any pH investigated. Fulvic acids had no effect upon either protease.

2. Inhibition of serine protease activity by humic acids was reversed by increasing the pH to 9, as well as increasing the ionic strength by addition of CaCl2‐ It was concluded that the interaction between humic acids and the serine protease was primarily ionic.

3. The formation of a humic acid‐serine protease complex increased the half‐life of enzymatic activity in dilute solutions. Humic acids had no effect on the stability of the metalloprotease.

4. There was no clear effect of humic acids on the growth of A. hydrophila, indicating that either the serine protease is not involved in the rate‐limiting step of growth or that sufficient activity exists even when the serine protease is inhibited by humic acids.

5. Increasing the enzymatic lifetime through association with humic acids may be an adaptive mechanism which could result in energy conservation due to a decreased requirement for protein synthesis.
Variation in reproductive characteristics of colonies of the freshwater bryozoan Cristatella mucedo
Authors: UOTILA LAURA , JOKEL JUKKA
Published: May 2006

1. We studied relationships between different forms of reproduction and local variation in the reproductive state of colonies of a common freshwater bryozoan Cristatella mucedo Cuvier (Bryozoa: Phylactolaemata). Four sampling locations in central Finland, including both lotic and lentic habitats, were sampled by scuba diving. The traits studied were occurrence of sexual larvae, colony size, number of resting stages (statoblasts) and number of zooids.

2. While 76.9% of the sampled colonies carried statoblasts at the time of sampling, only 4.5% of the colonies were brooding sexual larvae. Most of the colonies were relatively small with a mean colony size of 16.6 mm.

3. In colonies brooding larvae, the number of statoblasts was positively correlated with the number of larvae. We did not detect a colony size threshold for sexual reproduction or formation of statoblasts. Colonies carrying statoblasts had a lower number of zooids per unit dry weight.

4. We found significant variation in reproductive traits of colonies among the sampling locations, and among lotic and lentic habitats. The observed phenotypic differences may reflect broadly distributed, phenotypically plastic clones. Differences in clonal composition of local populations cannot, however, be ruled out and factors that may provide clonal diversity are discussed.
How do predator‐induced changes affect prey vulnerability? Larvae of Chaoborus flavicans (Diptera: Chaoboridae) feeding on Daphnia pulex (Crustacea: Cladocera)
Authors: LÜNING JULIA
Published: May 2006

1. The relative food consumption and prey preferences of fourth‐instar larvae of the phantom midge Chaoborus flavicans were investigated in laboratory experiments. Neonates and second instars of two clones of the cladoceran Daphnia pulex ‐ an Arctic and an European clone ‐ were offered to the predatory larvae. Each clone was divided into two groups: one group was exposed to the midge larvae during embryogenesis, whereas the other was not exposed to the predator.

2. While both exposed and unexposed neonates of the European clone had neck teeth, animals of the Arctic clone did not develop these spines.

3. A consistent rank order was observed in the vulnerability of the four prey types. Newborn daphnids from the Arctic clone were more vulnerable to predation than those from the European clone. Moreover, differences existed within each clone, regardless of neck teeth induction: Daphnia previously exposed to Chaoborus were less susceptible to the predators than unexposed prey.

4. The results show differences in the vulnerability of exposed and unexposed neonates that are not caused by the presence or absence of neck teeth. Perhaps the reduced vulnerability of exposed neonates was due to predator‐avoidance behaviours.
A hierarchical study of macroinvertebrate recolonization of disturbed patches along a longitudinal gradient in a prairie river
Authors: JOHNSON S.L. , VAUGHN C.C.
Published: May 2006

1. Macroinvertebrate densities and community composition were examined at three spatial scales after substratum disturbance; among reaches along a longitudinal gradient, within reaches and within plots. Reaches consisted of sandstone outcrops that were separated by approximately 2 km of highly mobile sandy silt substratum.

2. Substrata were disturbed by scraping sandstone plots (0.3 ± 0.3 m). Body‐sized depressions created by Trichoptera in the sandstone were removed along with the upper 5 mm of sandstone, resulting in areas of newly exposed, smooth sandstone.

3. The spatial scale of examination determined whether patterns of macroinvertebrate distribution and densities were discernible. Initially there were no significant differences in community composition or total densities among reaches or among upstream/ downstream locations within reaches. Following substratum disturbance and 30 days recolonizarion, total macroinvertebrate densities did not differ significantly between undisturbed plots and disturbed plots. However, densities of Petrophilia (Pyralidae: Lepidoptera) differed along the longitudinal gradient and the Simuliidae had its highest density in the upstream reach. Significant differences were found in total macroinvertebrate densities between the upstream and the downstream halves of disturbed plots, with higher densities occurring in the downstream portions.

4. Recolonized plots had similar macroinvertebrate densities and community composition to undisturbed plots, suggesting that the stream community was highly resilient.
APPLIED ISSUES Species‐ and population‐specific responses of translocated hydropsychid larvae (Trichoptera, Hydropsychidae) to runoff from acid sulphate soils in tin River Kyrönjoki, western Finland
Authors: VUORI KARI‐MATTl
Published: May 2006

1. The effects of runoff from acid sulphate soils on Hydropsyche angustipennis, H. siltatai and Ceratopsyche nevae larvae were studied. H. angustipennis occurs in both contaminated and uncontaminated rivers, whereas H. siltalai and C. nevae occur only in uncontaminated rivers. Larvae were translocated in PVC‐tubes to contaminated sites. Larvae returned to an uncontaminated river were used as a control.

2. Heavy larval mortality and a high incidence of morphological abnormalities were observed in larvae translocated to the contaminated, acid dyers. In the control river pH remained near 6 and no larval mortality or morphological abnormalities were observed. In the most contaminated river nutrient concentrations, amount of organic matter and pH increased substantially after the flood.

3. Mortality and incidence of abnormalities were significantly higher in H. siltalai and C. nevae than in H. angustipennis. As metal concentrations decreased and pH increased, the larvae of all species developed normally, except in the most contaminated river, where only H. angustipennis appeared to tolerate the increasing load of nutrients and organic matter.

4. Reciprocal translocation of H. angustipennis larvae between contaminated and uncontaminated rivers revealed significant differences in larval development and the occurrence of abnormalities among sites and populations. At both sites, larvae originating from the contaminated site grew more slowly than did larvae from the uncontaminated site. Morphological abnormalities were detected only in H. angustipennis larvae translocated from the uncontaminated to the contaminated site.

5. The results suggest that species‐specific differences in sensitivity to acidification, metal contamination and eutrophication are the major determinants of hydropsychid guild structure in the River Kyrönjoki. Further, population‐specific differences in growth and occurrence of morphological abnormalities in the H. angustipennis larvae may reveal either phenotypic adaptation or evolution of resistance to runoff from acid sulphate soils.
Parry–Romberg syndrome: a report of the dental findings in a child followed up for 9 years
Authors: O’FLYNN S. , KINIRONS M.
Published: May 2006

Summary.  Introduction.  The incidence of Parry–Romberg syndrome (PRS) is very rare.

Case Report.  A case report is presented highlighting the main dental aspects that include delayed eruption, root resorption, dilacerations, and a reduction in the height and width of the ramus and body of the mandible on the affected side.
Dental treatment of children referred to general anaesthesia – association with country of origin and medical status
Authors: HAUBEK D. , FUGLSANG M. , POULSEN S. , RØLLING I.
Published: May 2006

Summary.  Background.  A small proportion of children and adolescents need dental treatment with general anaesthesia (DGA). The aim of this retrospective cross‐sectional study was to analyse how country of origin and medical status were related to age at treatment, waiting times in the system, and dental treatment provided in general anaesthesia.

Methods.  A total of 786 patients received DGA at the University Hospital of Aarhus, Denmark in the period from 1990 to 2001. Information on the date of referral, the date of examination, the date of treatment, country of origin (Danish or non‐Danish), medical status (non‐special needs or special needs), and dental treatment performed was collected from patient records.

Results.  Patients with special needs were older when treated than non‐special needs patients, whereas patients with a non‐Danish origin were younger than those with a Danish origin when treated. There were no differences between non‐special needs and special needs patients in waiting times from referral to examination and from examination to dental treatment. In contrast, patients from a non‐Danish origin waited longer from examination to treatment than patients of Danish origin, whereas no difference was found in waiting time from referral to examination. Patients with special needs had fewer teeth treated than non‐special needs patients, whereas patients with non‐Danish origin had more teeth treated than those of a Danish origin.

Conclusion.  Age at treatment, waiting times in the system, and dental treatment received under general anaesthesia vary according to medical status and country of origin of the patients in Denmark. These findings should be considered in the organization and the funding of this type of service.
Concomitant developmental dental anomalies in Chinese children with dens evaginatus
Authors: CHO S. Y. , KI Y. , CHU V. , CHAN J.
Published: May 2006

Summary.  Aim.  To determine the prevalence of concomitant developmental dental anomalies in a group of Chinese children with dens evaginatus.

Methods.  The dental records and orthopantomograms of 10–15 year old children and adolescents who had been diagnosed with dens evaginatus in a school dental clinic were reviewed retrospectively.

Results.  Four hundred and forty‐eight of 7102 (6·3%) children were found to have dens evaginatus. Concomitant developmental dental anomalies were found in 77 children (17·2%). The most commonly seen dental anomalies in the study population were hypodontia, hyperdontia, microdontic maxillary lateral incisor, and dental impaction. The prevalence of these anomalies did not differ significantly to that found in the general Chinese population. When analysed separately, however, the prevalence of supernumerary premolars was found to be higher in children with dens evaginatus than in the general population, and the difference was statistically significant (P < 0·01).

Conclusion.  Supernumerary premolars appeared to be more prevalent in Chinese children with dens evaginatus than in the general population. There may be an association of supernumerary premolars with dens evaginatus in this study population.
Physical activity and physical self‐concept: comparison between children with and without asthma
Authors: Chiang Li‐Chi , Huang Jing‐Long , Fu Lin‐Shien
Published: May 2006

Aim.  This paper reports a study comparing levels of physical activity and physical self‐concepts between children with and without asthma.

Background.  Childhood asthma has become one of the world's most prevalent chronic illnesses. Its symptoms are thought to prevent children from participating in some forms of physical activity. However, asthma treatment guidelines are increasingly suggesting that children with asthma can participate in the same physical activities as healthy children for the same reasons – to promote normal growth, physical development and psychological health.

Method.  Between October 2001 and May 2002, 120 children between the ages of 9 and 11 with mild and moderate asthma were recruited from three paediatric asthma clinics in Taiwan, and 309 non‐asthmatic children in the same age group were selected from four elementary schools in Taiwan's three largest cities. Participants were asked to record physical activity levels for 3 days out of the past 7 days and to fill out a 29‐item Physical Self‐Concept Inventory. Physical activities were classified as moderate‐to‐vigorous physical activity or vigorous physical activity. Physical self‐concept was measured in terms of perceived flexibility, endurance, appearance, agility, obesity and strength.

Results.  Asthma was the primary factor determining vigorous physical activity levels, but gender was the primary factor determining physical self‐concept, especially in terms of endurance, obesity and strength. No statistically significant relationships were noted between asthma and gender in terms of effects on physical activity and physical self‐concept.

Conclusions.  Asthma interferes with children's ability to participate in vigorous physical activity but not in moderate‐to‐vigorous physical activity. Gender determines primary differences in physical self‐concept. Appropriate exercise recommendations are necessary to encourage children with asthma to engage in vigorous physical activity for normal growth.
Evaluating STORM skills training for managing people at risk of suicide
Authors: Gask Linda , Dixon Clare , Morriss Richard , Appleby Louis , Green Gillian
Published: May 2006

Aim.  This paper reports a study evaluating the Skills Training On Risk Management (STORM) training initiative in three mental health services in the North‐West of England, UK.

Background.  Training for health workers has been widely advocated as a key route to suicide prevention. However, reports of evaluations are scarce in the literature. In previous research, we have demonstrated that the STORM intervention results in acquisition of new skills and can be disseminated in a community setting.

Method.  The training was delivered during a 6‐month period in 2002 by three mental health nurses who were seconded part‐time to the project. The quantitative evaluation, which assessed change in attitudes, confidence, acquisition of skills and satisfaction, used a pretest/post‐test design, with participants acting as their own controls. Qualitative interviews were conducted with a purposive sample of 16 participants to explore the impact on clinical practice, and with the three trainers at the end of the study.

Findings.  Data from 458 staff members were collected during a 6‐month period. Positive changes in attitudes and confidence were shown, but previous evidence of skill acquisition was not replicated. Qualitative interviews revealed important insights into changes in clinical practice, particularly for less experienced or unqualified nursing staff, but also concerns about the lack of an educational culture to foster and support such interventions in practice within the organizations.

Conclusion.  STORM training for the assessment and management of suicide risk is both feasible and acceptable in mental health trusts. However, we remain uncertain of its longer‐term impact, given the lack of engagement of senior staff in the enterprise and the absence of linked supervision and support from the organizational management to reinforce skill acquisition and development. We consider that regular supervision that links STORM training to actual clinical experience would be the ideal.
Does pond quality limit frogs Rana arvalis and Rana temporaria in agricultural landscapes? A field experiment
Authors: LOMAN JON , LARDNER BJÖRN
Published: May 2006

When assessing the cause of population absence or decline, it is important to understand the relative effect of local, regional and global factors. In this study we evaluated the first of these factors for two frog populations.

Amphibians are often absent from intensively farmed areas. There could be several reasons for this, one of them being the quality of the aquatic habitat available for reproduction.

In order to test why common frogs Rana temporaria and moor frogs Rana arvalis are absent from most ponds in the intensively agricultural areas of southern Sweden, we performed a field experiment. Spawn of both species were introduced into 18 ponds surrounded by intensively cropped fields.

Tadpole performance generally did not differ from that in a set of reference ponds in various other habitat types where one or both of these frog species occurs naturally.

In the same experimental ponds and in a number of reference ponds, we also introduced tadpoles of the two species into enclosures that protected them from predation and thus increased recapture rate. This experiment revealed that the water quality of farmland ponds is rarely unsuitable for successful frog reproduction.

Having measured abiotic and biotic variables in the experimental and reference ponds, we assessed the importance of different parameters to tadpole performance. While farmland ponds generally had higher pH, higher conductivity and higher nitrate and nitrite concentrations than our reference ponds, these factors had no discernible effects on tadpole performance under the ranges found across all pond types. None of the other parameters differed between the two groups of ponds, nor did they have any strong or obvious effects on tadpole performance or survival.

Synthesis and applications. The results indicate that water quality alone is not responsible for the scarcity of amphibians in farmland areas of southern Sweden. To understand better the cause of their rarity, future studies should also focus on the quality of the terrestrial habitat surrounding the ponds and the metapopulation structure.
Host invasion during rice‐blast disease requires carnitine‐dependent transport of peroxisomal acetyl‐CoA
Authors: Ramos‐Pamplona Marilou , Naqvi Naweed I.
Published: May 2006

In lower eukaryotes, beta‐oxidation of fatty acids is restricted primarily to the peroxisomes and the resultant acetyl‐CoA molecules (and the chain‐shortened fatty acids) are transported via the cytosol into the mitochondria for further breakdown and usage. Using a loss‐of‐function mutation in the Magnaporthe grisea PEROXIN6 orthologue, we define an essential role for peroxisomal acetyl‐CoA during the host invasion step of the rice‐blast disease. We show that an Mgpex6Δ strain lacks functional peroxisomes and is incapable of β‐oxidation of long‐chain fatty acids. The Mgpex6Δ mutant lacked appressorial melanin and host penetration, and was completely non‐pathogenic. We further show that a peroxisome‐associated carnitine acetyl‐transferase (Crat1) activity is essential for such appressorial function in Magnaporthe. CRAT1‐minus appressoria showed reduced melanization, but were surprisingly incapable of elaborating penetration pegs or infection hyphae. Exogenous addition of excess glucose during infection stage caused partial remediation of the pathogenicity defects in the crat1Δ strain. Moreover, Mgpex6Δ and crat1Δ mycelia showed increased sensitivity to Calcofluor white, suggesting that weakened cell wall biosynthesis in a glucose‐deficient environment leads to appressorial dysfunction in these mutants. Interestingly, CRAT1 was itself essential for growth on acetate and long‐chain fatty acids. Thus, carnitine‐dependent metabolic activities associated with the peroxisomes, cooperatively facilitate the appressorial function of host invasion during rice‐blast infections.
Peroxisomal carnitine acetyl transferase is required for elaboration of penetration hyphae during plant infection by Magnaporthe grisea
Authors: Bhambra Gurpreet K. , Wang Zheng‐Yi , Soanes Darren M. , Wakley Gavin E. , Talbot Nicholas J.
Published: May 2006

Magnaporthe grisea, the causal agent of rice blast disease, invades plant tissue due to the action of specialized infection structures called appressoria, which are used to breach the leaf cuticle and allow development of intracellular, infectious hyphae. In this report we demonstrate that peroxisomal carnitine acetyl transferase (CAT) activity is necessary for appressorium function, and in particular, for the elaboration of primary penetration hyphae. The major CAT activity in M. grisea is encoded by the PTH2 gene, which shows elevated expression in response to acetate and lipid, and is regulated by the cyclic AMP response pathway. Furthermore, a Pth2–GFP fusion protein colocalizes with a peroxisomal marker protein. Targeted deletion of PTH2, generated mutants that were completely non‐pathogenic, lacked CAT activity and were unable to utilize a range of lipid substrates. The impairment of appressorium function in Δpth2 was associated with a delay in lipid reserve mobilization from germ tubes into developing infection cells, and abnormal chitin distribution in infection structures. Addition of glucose to Δpth2 mutants partially restored the ability to cause rice blast disease and lipid reserve mobilization. Taken together, our findings provide evidence that Pth2 plays a role in the generation of acetyl CoA pools necessary for appressorium function and rapid elaboration of penetration hyphae during host infection.
IscR acts as an activator in response to oxidative stress for the suf operon encoding Fe‐S assembly proteins
Authors: Yeo Won‐Sik , Lee Joon‐Hee , Lee Kyung‐Chang , Roe Jung‐Hye
Published: May 2006

In Escherichia coli, Fe‐S clusters are assembled by gene products encoded from the isc and suf operons. Both the iscRSUA and sufABCDSE operons are induced highly by oxidants, reflecting an increased need for providing and maintaining Fe‐S clusters under oxidative stress conditions. Three cis‐acting oxidant‐responsive elements (ORE‐I, II, III) in the upstream of the sufA promoter serve as the binding sites for OxyR, IHF and an uncharacterized factor respectively. Using DNA affinity fractionation, we isolated an ORE‐III‐binding factor that positively regulates the suf operon in response to various oxidants. MALDI‐TOF mass analysis identified it with IscR, known to serve as a repressor of the iscRSUA gene expression under anaerobic condition as a [2Fe‐2S]‐bound form. The iscR null mutation abolished ORE‐III‐binding activity in cell extracts, and caused a significant decrease in the oxidant induction of sufA in vivo. OxyR and IscR contributed almost equally to activate the sufA operon in response to oxidants. Purified IscR that lacked Fe‐S cluster bound to the ORE‐III site and activated transcription from the sufA promoter in vitro. Mutations in Fe‐S‐binding sites of IscR enabled sufA activation in vivo and in vitro. These results support a model that IscR in its demetallated form directly activates sufA transcription, while it de‐represses isc operon, under oxidative stress condition.
Identification of potyviruses infecting vanilla by direct sequencing of a short RT‐PCR amplicon
Authors: Grisoni M. , Moles M. , Farreyrol K. , Rassaby L. , Davis R. , Pearson M.
Published: May 2006

A simple one‐tube one‐step RT‐PCR assay with degenerate primers followed by direct sequencing of a 327 bp coat protein gene fragment was used to identify the potyviruses infecting vanilla. With this technique, unambiguous species allocation was achieved for 34 potyvirus‐infected vanilla samples collected in the Indian Ocean and the Pacific areas between 1997 and 2005. Virus identification relied on blast homology and nucleotide identities of 162 to 327 nt fragments with known potyvirus sequences. Species allocation was confirmed by neighbour‐joining of the 149 nt common to 32 vanilla sequences and 51 known potyviruses. Subject to further identification, these data revealed four additional Potyvirus species that may infect vanilla: Bean yellow mosaic virus, Cowpea aphid‐borne mosaic virus, Ornithogalum mosaic virus and Wisteria vein mosaic virus. The procedure was rapid, cost‐effective, easy to use and showed a good taxonomic discriminating value. It also enabled the identification of potyviruses in adjacent weeds and should thus aid the understanding of outbreaks of potyviruses occurring in varied epidemiological circumstances.
Smallpox vaccination site reactions: two cases of exaggerated scarring and a brief review
Authors: Waibel Kirk H. , Walsh Douglas S.
Published: May 2006

Case 1

A 26‐year‐old, healthy white woman received her first smallpox vaccination (Dryvax®, Wyeth Laboratories, Inc., PA, USA) 9 months prior to presentation. By history, the vaccine site progressed through typical postvaccinia changes, but eventually developed a nodule that was cosmetically bothersome. There was no history of atypical scar formation. On physical examination, there was an 8 mm × 8 mm, firm, nontender, flesh‐colored nodule on the left upper arm (Fig. 1a). The patient elected to receive an intralesional triamcinolone acetonide injection (Kenalog®, Bristol‐Myers Squibb Co., Princeton, NJ, USA) (0.1–0.2 mL of 5 mg/mL). After 2 weeks, the nodule had softened, was about 50% smaller, and the treatment was repeated.

Case 1 (a) and Case 2 (b)

image

Case 2

A 19‐year‐old, healthy African‐American man received his first smallpox vaccination (Dryvax®, Wyeth Laboratories, Inc., PA, USA) 8 months prior to presentation and described typical lesion progression, with a residual, mildly hyperpigmented macule. Within 3 months, the macule had developed plaque‐like features that persisted until presentation; the lesion was cosmetically bothersome. There was no history of spontaneous or post‐traumatic hypertrophic scarring or keloid formation. On physical examination, there was a firm, nontender, 10 mm × 10 mm hyperpigmented plaque (Fig. 1b). The patient elected to receive the same treatment as Case 1 and showed marked improvement within 2 weeks.
Association of penile lichen sclerosus and oncogenic human papillomavirus infection
Authors: Nasca Maria Rita , Innocenzi Daniele , Micali Giuseppe
Published: May 2006

Background  Data on the prevalence of human papillomavirus (HPV) infection in patients with penile lichen sclerosus (LS) are scant and controversial.

Aim  To investigate the prevalence of HPV infections in patients with penile LS.

Methods  HPV infection was assessed by polymerase chain reaction (PCR) in paraffin‐embedded penile biopsies obtained from the glans or inner foreskin of 46 adult patients with penile LS, and in brush cytology smears of penile healthy mucosa from an equal number of randomly selected control males matched for age. Statistical evaluation was performed using conditional logistic regression analysis.

Results  PCR disclosed the presence of HPV infection in 17.4% of LS patients (HPV 16, six cases; HPV 18, one case; HPV 45, one case). Amongst the controls, HPV infection occurred in 8.7% of patients (HPV 16, two cases; HPV 53, one case; HPV 70, one case). Statistical regression analysis confirmed that the rate of HPV infection was higher amongst patients with genital LS than amongst healthy controls [odds ratio (OR), 2.55; 95% confidence interval (CI), 0.73–8.89].

Conclusions  Infection with oncogenic “high‐risk” HPV types in patients with genital LS may enhance the risk of penile cancer arising on LS.
Interrelations among pressure–volume curve traits across species and water availability gradients
Authors: Lenz Tanja I. , Wright Ian J. , Westoby Mark
Published: May 2006

Pressure–volume (P–V) curves for leaves or terminal shoots summarize leaf‐level responses to increasing water deficit. P–V curve traits and field‐measured shoot xylem pressures were characterized across 62 species from four sites differing in rainfall and soil phosphorus. Within‐species variation in the measured traits was small relative to differences among species and between environments. P–V curve traits tended to differ with site rainfall but not with soil phosphorus. Turgor loss points (TLPs) varied widely and averaged more negative in species from lower‐rainfall sites. Differences between species in TLP were driven mainly by differences in solute potential, rather than by differences in cell wall elasticity. Among species at individual sites, species seemed to vary in leaf‐response strategy reflected in TLP independently from water‐uptake strategy reflected in predawn xylem pressures and in xylem pressure drop from predawn to midday.
Short episodes of water stress increase barley root resistance to radial shrinkage in a dehydrating environment
Authors: Lemcoff Jorge Hugo , Ling Fan , Neumann Peter M.
Published: May 2006

Although plant shoots can be ‘hardened’ by abiotic stresses, little is known about such changes in roots. In order to investigate possible induction of root‐hardening in response to short water‐stress episodes, barley seedlings (Hordeum vulgareL) hydroponically grown under a controlled environment were moderately water‐stressed by addition of a non‐penetrating osmoticum, polyethylene glycol (PEG) 6000 at −0.4 MPa water potential, to the aerated nutrient solution. Seedlings were then hydrated in dilute nutrient solution without PEG before excision and assay of the seminal roots. Previous water stress treatments for 72 h, 12 h, or even 6 h induced an apparent root‐hardening process. Thus, root radial shrinkage during subsequent exposure to strongly dehydrating conditions was remarkably decreased. The root hardening was related to biophysical adjustments: turgor‐pressure increased while osmotic potential decreased from −0.45 ± 0.02 MPa to −0.60 ± 0.02 MPa. Moreover, the maximum bulk volumetric modulus of elasticity, ?maxdetermined by pressure–volume analysis, increased from 2.1 ± 0.4 MPa to 3.7 ± 0.4 MPa, i.e. root elasticity was decreased. Root hardening in response to episodes of water stress may have ecological significance for barley plants in regions where intermittent drought episodes are frequent.
Predictors of chronic allograft nephropathy from protocol biopsies using histological and immunohistochemical techniques
Authors: YEHIA MAHA , MATHESON PHILIP J , MERRILEES MERVYN J , BEAUMONT BRENT W , PILMORE HELEN L
Published: May 2006

Aim:  Chronic allograft nephropathy is a predictor of poor allograft survival. Protocol and diagnostic biopsies were used to identify markers contributing to its pathogenesis.

Methods:  Diagnostic, 3‐ and 12‐month protocol biopsies in renal transplant recipients were examined. Immunohistochemical staining with monoclonal antibodies for memory T cells (CD45RO), macrophages (CD68) and alpha smooth muscle actin was undertaken on protocol biopsies.

Results:  Protocol biopsies revealed the incidence of chronic allograft nephropathy to be 10.7% (3/28) at 3 and 57.6% (19/33) at 12 months. There was a trend towards a higher serum creatinine in patients with chronic allograft nephropathy compared with those without (0.15 ± 0.04 vs 0.12 ± 0.04 mmol/L, P = 0.047). The strongest predictor of chronic allograft nephropathy at 12 months was the presence of arteriolar hyaline change (P = 0.035; odds ratio 1.22, 95% CI 0.036–0.887) whereas a higher CD45RO and CD68 count at 12 months was associated with chronic allograft nephropathy (74.7 ± 56.9 cells/mm2 and 22.4 ± 23.5 cells/mm2) compared with patients without it (29.2 ± 29.2 cells/mm2 and 8.3 ± 9.9 cells/mm2, P = 0.006 and P = 0.03, respectively). The number of smooth muscle actin positive cells correlated significantly with chronic allograft nephropathy at 12 month (107.6 ± 44 vs 73.9 ± 20.8 cells/mm2, P = 0.009).

Conclusion:  The high prevalence of chronic allograft nephropathy in renal transplant recipients is associated with renal dysfunction. Arteriolar hyalinosis was the most significant predictor at 12 months. There was a significantly higher macrophage and T cell infiltrate in stable grafts undergoing chronic allograft nephropathy at 12 months post transplant.
Kidney‐specific gene targeting: Insight into thiazolidinedione‐induced fluid retention (Review Article)
Authors: YANG TIANXIN
Published: May 2006

SUMMARY: Conditional gene targeting technique, which is based on the use of Cre‐loxP or Flp/FRT systems, has been increasingly used to study gene function of a particular cell typein vivo.The introduction of this technique to the kidney field is relatively recent but has already provided important insights into physiological or pathological functions of a number of genes in the kidney. This technique has recently been used to inactivate the peroxisome proliferator‐activated receptor subtype γ in the collecting duct, which leads to remarkable blockade of body weight gains and plasma volume expansion associated with thiazolidinediones. This finding not only helps understand pharmacology of the novel class of antidiabetic drugs, but also uncovers an important role of peroxisome proliferator‐activated receptor subtype γ in regulation of distal nephron fluid reabsorption. The present review represents an example for the use of the modern technique to address complex clinical problems. It is anticipated that over next few years this technique will be used by an increasing number of investigators for studying gene function in the kidney.
Elimination and clearance of pamidronate by haemodialysis (Brief Communication)
Authors: BUTTAZZONI MIRENA , ROSA DIEZ GUILLERMO J , JAGER VICTOR , CRUCELEGUI MARIA S , ALGRANATI SALOMON L , PLANTALECH LUISA
Published: May 2006

SUMMARY:  Pamidronate (APD), a third‐generation bisphosphonate, has proven to be useful in haemodialysis (HD) patients with ectopic calcifications and hypercalcaemia. Little is known about bisphosphonates clearance in patients undergoing HD. The authors’ main objective was to study HD removal and clearance of APD. In total, 23 HD‐requiring anuric end‐stage renal disease (ESRD) adult individuals (12 men) aged 61.7 ± 13 (mean ± SD) years were admitted into the study. APD clearance and elimination were evaluated by 99mTechnetium APD (half‐life 6 h). In total, 1 mg of labelled APD was injected via the arteriovenous graft prior to the start of HD. Blood samples were then drawn from the arterial (predialyser) and venous (postdialyser) lines of the extracorporeal circuit 2 h after the HD onset. In a subgroup of patients (n: 15) the dialysate was collected and quantified during the three initial HD hours. Venous APD concentrations (postdialyser) were 72 + 7% of arterial (predialyser) concentrations. Mean APD clearance was 69.3 + 16.6 mL/min, and mean APD extraction during dialysis session was 31.6 + 10.1%. In the present study involving HD‐requiring anuric ESRD patients APD was successfully eliminated by HD. At the dose administered here none of the participants reported adverse events. APD is a potentially useful drug to be administered to HD‐requiring ESRD patients, the understanding of its removal during HD as well as its dialytic clearance allows for a safer management of a drug that is usually eliminated by renal excretion.
Current status of dosing and quantification of acute renal replacement therapy. Part 1: Mechanisms and consequences of therapy under‐delivery (Review Article)
Authors: MARSHALL MARK R
Published: May 2006

SUMMARY:  The dosing and quantification of acute renal replacement therapy has emerged as one of the most pressing issues in the management of critically‐ill patients with acute kidney injury. Although there is ongoing debate as to the best marker of uraemic injury in this setting, several landmark studies have identified clearance‐related expressions of acute renal replacement therapy dose as important determinants of survival. Part 1 of this review examines the factors affecting delivery of prescribed acute renal replacement therapy dose. The review continues in Part 2 and examines the implications of recent advances in this area for clinical practice.
Determining the life cycle of bolts using a local approach and the Dang Van criterion
Authors: FARES Y. , CHAUSSUMIER M. , DAIDIE A. , GUILLOT J.
Published: May 2006

The fatigue behaviour of bolts under axial load has always been considered from the component point of view for which fatigue limit is usually taken equal to 50 MPa, and few results are available to designers for limited lifetimes. Here, we take up this problem from a material point of view using a local approach. For each case of fatigue testing, using finite‐element (FE) model of the bolt, we determine the stabilized local stress at the root of the first thread in contact with the nut. To characterize bolt behaviour with these numerical results, we use Dang Van multiaxial fatigue criterion for which we extend application to the medium fatigue life. These results can be correlated with the experimental numbers of cycles to failure to determine material parameters of the generalized criterion. Using statistical Gauss method, we can make lifetime predictions for any level of risk of failure. In addition, we propose an analytical model to rapidly determine the local stress condition from nominal loading data (mean stress and alternating stress). This model dispenses us from a new modelling if the bolt is stressed in the same manner as the bolts used for behaviour characterization. Using this model and the generalized criterion, it is extremely easy to make lifetime predictions whatever the risk considered.
Distributions of exotic plants in eastern Asia and North America
Authors: Guo Qinfeng , Qian Hong , Ricklefs Robert E. , Xi Weimin
Published: May 2006

Although some plant traits have been linked to invasion success, the possible effects of regional factors, such as diversity, habitat suitability, and human activity are not well understood. Each of these mechanisms predicts a different pattern of distribution at the regional scale. Thus, where climate and soils are similar, predictions based on regional hypotheses for invasion success can be tested by comparisons of distributions in the source and receiving regions. Here, we analyse the native and alien geographic ranges of all 1567 plant species that have been introduced between eastern Asia and North America or have been introduced to both regions from elsewhere. The results reveal correlations between the spread of exotics and both the native species richness and transportation networks of recipient regions. This suggests that both species interactions and human‐aided dispersal influence exotic distributions, although further work on the relative importance of these processes is needed.
Fostering collaborative knowledge construction in a video‐based learning setting: effects of a shared workspace and a content‐specific graphical representation
Authors: Hron Aemilian , Cress Ulrike , Hammer Karsten , Friedrich Helmut‐Felix
Published: May 2006

This study examined means of fostering videoconference‐based collaborative learning. An experiment was conducted with 15 learning dyads divided into three conditions of videoconference‐based learning: without shared workspace, with shared workspace and with shared workspace plus a content‐specific graphical representation. Compared with those with a shared workspace, learning dyads without a shared workspace in the videoconference‐based setting tended to make more effort at verbal coordination. This coordination effort did not affect the quality of collaboratively written texts or individual knowledge acquisition. Without shared workspace, participants’ coordinative utterances involved more frequent referrals to the learning content, which might have facilitated the cognitive processing of the learning content and might have compensated for the potential disadvantage of verbal coordination load. The content‐specific graphical representation led to more coherent content‐related dialogues and had positive effects on the quality of the collaboratively written texts and on individual knowledge acquisition. The study shows that content‐specific graphical representation can be a meaningful support measure in videoconference‐based learning settings, whereas the effects of a shared workspace should be further investigated.
Comparing asynchronous online discussions and face‐to‐face discussions in a classroom setting
Authors: Wang Qiyun , Woo Huay Lit
Published: May 2006

The purpose of this study is to investigate the perceived differences between asynchronous online discussions and face‐to‐face discussions in a classroom setting. The students’ reflections were analysed by following a qualitative research approach. The results showed that atmosphere, response, efficiency, interactivity and communication were the top five themes that differ between asynchronous online and face‐to‐face discussions. Implications for designing asynchronous online and face‐to‐face discussions are discussed.
Age and novelty: Event‐related brain potentials and autonomic activity
Authors: Weisz Júlia , Czigler István
Published: May 2006

Our aim was to study age‐related differences in the habituation of orienting reaction by using novel visual stimuli. We intended to fill a gap in habituation research by recording both autonomic and ERP components of orienting to visual stimuli in the same sample and in highly related paradigms. We report data showing that in young subjects repetition of visual novels yielded fast habituation of both skin conductance responses and ERP components (P3novel, N2b) whereas elderly people displayed no sign of habituation. However, cardiac deceleration—thought conventionally to be part of the orienting reaction—did not habituate in either group. Overall, most of our results harmonize with those obtained by using auditory stimuli; therefore we conclude that there is no significant modality specificity in age‐related deterioration of habituation processes.
Effects of monetary reward and punishment on stimulus‐preceding negativity
Authors: Ohgami Yoshimi , Kotani Yasunori , Tsukamoto Tetsuji , Omura Kazufumi , Inoue Yusuke , Aihara Yasutsugu , Nakayama Minoru
Published: May 2006

This study examined the effects of emotional valence on stimulus‐preceding negativity (SPN) using reward and fine. A time estimation task under reward, punishment, combined, and control conditions was performed. Participants were rewarded for accurate responses in the reward condition, and were fined for incorrect estimations in the punishment condition. in the combined condition, correct responses were rewarded and incorrect responses were fined. In the control condition, neither a reward nor fine was used. Results showed a significant interaction of condition × hemisphere. The SPN at the left hemisphere was increased in the reward condition. For the punishment effect, although it evoked right hemisphere dominance, no conditional difference was apparent at the right hemisphere. These results suggest that the SPN is affected by positive emotion: The left hemisphere activation might represent a pleasant emotion accompanying monetary gain.
INTERGOVERNMENTAL POLICY ON MULTINATIONAL CORPORATIONS
Authors: LAVER MICHAEL
Published: May 2006

Multinational corporations can play off host governments to minimise their tax payments in the absence of internationally coordinated fiscal policies. Without a supranational enforcement agency, most tax harmonization policies are unstable because one or another signatory always has an incentive to break ranks. This produces a sub‐optimal tax harvest for a group of host governments taken as a whole. This is a collective action problem for host governments which can be stated in the form of a Prisoner's Dilemma supergame. Equilibrium cooperative solutions have been suggested for this game which do not need higher authorities to enforce them. The application of these solutions to the host governments’ tax problem is discussed, with the conclusion that under certain conditions self‐policing tax harmonization agreements are possible.
THE EFFECT OF THE OPPOSITION PARTIES ON THE LEGISLATIVE OUTPUT IN A MULTI‐PARTY SYSTEM. THE BELGIAN CASE FROM 1965 TO 1971
Authors: DEWACHTER WILFRIED , LISMONT EDITH , TEGENBOS GUY
Published: May 2006

A content analysis of the 1965 platforms of all Belgian political parties provides a determination of the policy objectives for the next legislature so that a survey can be made of the completely, partially, and nonrealized objectives at the end of a two‐legislature (1965–1968 and 1968–1971) period according to government and opposition parties, according to party strength – which was in this period congruent with the duration of participation in the government – and according to the distinction made between the parties qualifying for government and the non‐elitist opposition parties. The degree of realization is established for the total number of platform planks, for the number of specific items per party, and according to the degree of importance and social repercussion of the distinct planks that could be realized. Although respectively in office for six, four, and two years, the CVP/PSC, the BSP–PSB and the PVV/PLP realized approximately the same number of planks. The nonelitist opposition party Volksunie realized a smaller but still considerable number of objectives. So did, but to a lesser extent, the other structural or antisystem opposition parties, RW, FDF and KPB–PCB. The interpretation of these results may lie in the loss of distinctiveness in the government–opposition model in a multi‐party system, the elitist consensus in Belgium which is shared by the three main parties, the function of the pressure party strategy and the conducting of opposition in dynamic terms of action.
SCANDINAVIAN CHRISTIAN DEMOCRACY: THROWBACK OR PORTENT?*
Authors: MADELEY JOHN T.S.
Published: May 2006

Advanced secularization in the Scandinavian countries has not resulted in the elimination of “the religious factor” from political life, rather has it led to a resurgence with the recent establishment in Sweden, Denmark and Finland of native counterparts to Norway's Christian People's Party. The article first examines the development of the characteristic religious cleavage structures of Scandinavia, from the imposed uniformity of the state churches in the early nineteenth century to the relatively open and competitive religious cultures of the twentieth century. The interrelationship between religious cleavages and political alignments is then examined and an attempt made to explain the failure of stable religious parties to emerge in the formative period of the party systems. Finally, the circumstances surrounding the later emergence of the religious parties are described and it is argued that these parties collectively constitute a new species of the genus Christian Democracy, different in kind from Fogarty's Continental and Anglo‐Saxon species.