bluuebunny/crossref_metadata_2025 huggingface dataset:
Persistent soil seed banks in Phacelia secunda (Hydrophyllaceae): experimental detection of variation along an altitudinal gradient in the Andes of central Chile (33 S)
Authors: Cavieres Lohengrin A. , Arroyo Mary T. K.
Published: March 2003

It is unclear whether soil seed banks in alpine environments are a result of selection for extended seed dormancy, of ideal conditions for seed preservation in the soil, or a combination of both.

 The nature of the soil seed bank was investigated in the perennial herb Phacelia secunda (Hydrophyllaceae) through reciprocal burial experiments using seeds obtained from populations growing at 1600, 2200, 2900 and 3400 m a.s.l. in the mediterranean Andes of central Chile. At the four elevations, six replicates of 50 seeds each, from each of the four elevational sources, were buried at 5 cm depth in mesh envelopes, placed in wire cages to protect against predation. Seeds were retrieved 1, 2 and 3 years after burial, and numbers of ungerminated seeds, and of those that remained viable, were determined.

 At all elevations of seed burial, increasing proportions of seeds remained ungerminated, and proportionately more of the ungerminated seeds remained viable, as elevation of source of seed increased. For seed from low elevation, more seeds remained viable in the soil at the higher burial sites. However, for the seeds from higher elevation sources, seeds remaining viable were similar in number at all sites for seed burial. Half‐lives of seed buried at the source elevation, calculated from the log‐logistic distribution, increased with elevation, and ranged from 188 days at 1600 m to 354 days at 3400 m.

 The results suggest that the propensity to form a persistent seed bank in P. secunda increases with elevation. Seeds from the highest elevations had the longest persistence, and this was largely unaffected by soil preservation conditions. Seeds from lower elevations survived for less time, and this was modifiable by preservation conditions. These results suggest that both selective effects and soil conditions may be involved in soil seed bank expression in the alpine environment.
Male and femaleSilene latifoliaplants differ in per‐contact risk of infection by a sexually transmitted disease
Authors: Kaltz Oliver , Shykoff Jacqui A.
Published: March 2003

Behavioural, physiological or immunological constraints often render one sex more susceptible to parasites, thereby potentially generating sex‐specific trade‐offs between traits associated with infection risk and other life‐history characters.

 The fungal pathogenMicrobotryum violaceumsystemically infects the dioecious plantSilene latifoliawhen pollinators deposit fungal spores on the flowers of healthy plants. Male plants produce many short‐lived flowers, whereas females produce few flowers that remain connected with the plant after fertilization. We investigated how variation in flower production and flower longevity affects the infection risk for males and females.

 In glasshouse experiments, we varied the number of flowers inoculated (4 vs. 16 per plant) with spores and the time until these flowers were removed (1 or 2 days for both sexes, 14 days for females only). We also measured the longevity of male flowers receiving simulated visits, with or without spores, to test for an abscission response to visitation and/or contamination. In a field survey, we measured male and female disease prevalence in 17 natural populations.

 Varying the number of inoculated flowers did not affect infection probability, but females retaining inoculated flowers for 14 days became diseased more often (20.0%) than did plants with flowers removed within 2 days (7.3%).

 Males that had dropped more inoculated flowers prematurely were more likely to remain uninfected. Spore‐bearing visits shortened male flower longevity (38.4 ± 2.8 h) relative to non‐spore visits (47.9 ± 5.2 h).

 Female field disease prevalence (19.7 ± 3.5%) was higher than that of males (14.3 ± 2.6%), especially in populations with a high disease incidence.

 Continuing physical connection during fruit ripening appears to increase invasion time and thus the per‐contact infection risk in females. This is consistent with higher female field prevalences, although other explanations, unrelated to disease transmission, are possible. These results illustrate how interactions between plant reproductive behaviour and pollinator activity may affect disease spread. Female mating behaviour may evolve towards lower attractiveness to pollinators to minimize infectious contacts, while males can afford to be more promiscuous with an attractive, but disposable, floral display.
Community assembly from the local species pool: an experimental study using congeneric species pairs
Authors: Tofts Richard , Silvertown Jonathan
Published: March 2003

1 Vegetation–environment relationships are well understood at the geographical scale, but it is still not clear what role chance and historical contigency play in the assembly of communities from the local species pool. We addressed this question experimentally by comparing the performance of congeneric species introduced into a grassland community.

2 We used the National Vegetation Classification and distribution maps to define the local pool of grassland species suited to our experimental site. From this we selected five pairs of congeneric species. One member of each pair was native to the experimental site (‘present’ species) and one member was represented in the local species pool but absent from the community (‘absent’ species).

3 If community assembly processes are deterministic, then absent species should underperform present congeners. Any other result would imply that chance, dispersal limitation or historical contingency plays a role in community assembly. Our experimental arrangement allowed us to assess the consistency of comparisons across different grazing treatment combinations.

4 Two field experiments were undertaken. The first investigated the effects of dispersal limitation by introducing seed of congeners and monitoring performance. The second investigated the survival of congeners introduced as small plants at the early stages of growth in ‘plugs’. A laboratory germination test and a combined analysis of both field experiments were also undertaken.

5 Some species showed markedly different responses from their congeners in the two field experiments. Overall, the present species did not consistently perform better than their absent congeners. This indicates that the study community bears the strong imprint of dispersal limitation or other historical factors, a finding consistent with results previously obtained for the same community using a trait‐based model.

6 We conclude that the accuracy of predictions about community composition will be limited by the success with which factors such as propagule dispersal and differential effects of seed predation and herbivory can be modelled. We predict the circumstances under which modelling of community assembly is most likely to be successful.
Contrasting effects of grazing and hay cutting on the spatial and genetic population structure of Veratrum album, an unpalatable, long‐lived, clonal plant species
Authors: Kleijn David , Steinger Thomas
Published: March 2003

1  Vegetation change induced by large herbivores is driven by the effects of grazers on populations of individual plant species. Short‐term experimental or demographic studies may be insufficient when investigating the population responses of long‐lived clonal plant species.

2
 We therefore examined the effects of grazing on such a plant (Veratrum album) by comparing the spatial and genetic structure of populations in grasslands subject to long‐term grazing or mowing for hay.

3
 
V. album is a locally dominant species that is avoided by large herbivores due to its toxicity. RAPD‐phenotypes of a subsample of c. 50 shoots, and co‐ordinates and dry weight of all shoots, were determined in a 5 × 10 m plot in each of four meadow and four pasture populations.

4
 The breeding system of the genus Veratrum was previously unknown but our experimental finding that cross‐pollinated but not self‐pollinated or unpollinated flowers produced as many seeds as freely pollinated flowers suggested that V. album is a predominantly cross‐pollinating species.

5  Both the spatial and genetic population structure differed markedly between the two grassland types. Clonal expansion of established plants in pastures led to populations consisting of larger shoots that were significantly more aggregated at a small spatial scale. Populations also had a higher proportion of flowering shoots, less seedling recruitment and a lower genotypic diversity in pastures than hay meadows.

6
 The differences in population structure appear to be due to hay meadow populations reproducing primarily by seeds, whereas clonal reproduction accounts for half of the population growth in pastures. We suggest that, as livestock selectively avoids V. album shoots, grazing indirectly promotes plant growth, which results in an enhanced vegetative reproduction as well as a higher seed production. Experimental studies are, however, needed to determine why and how grazing adversely affects seedling recruitment.

7  Detailed information on population level responses of unpalatable dominant plant species, such as provided by the present study, may help us understand and predict vegetation change in response to changing levels of herbivory.
Modelling individual growth and competition in plant populations: growth curves of Chenopodium album at two densities
Authors: Damgaard Christian , Weiner Jacob , Nagashima Hisae
Published: March 2003

We modelled the growth in estimated biomass of individuals in experimental populations of Chenopodium album grown at two densities and measured sequentially nine times over 128 days. Competition is modelled by coupling individual growth equations and, within the population, the growth rate of a plant at any point in time is a function of its size to the power a, a measure of the degree of size‐asymmetry of competition.

The growth of individuals in these crowded populations was significantly better fit by a Richards growth model than by models with one fewer parameter (e.g. logistic or Gompertz growth models). The additional parameter determines the location of the inflection point and provides great flexibility in fitting growth curves. Density had a significant effect on this parameter.

At the higher density, the maximum size that plants achieved was decreased and the exponential phase of growth was reduced. The estimate of the size‐asymmetry parameter a was always greater than 1 and it increased significantly at the higher density. Growth was reduced and the number of very small individuals increased at the higher density, although a few plants still achieved a large size.

Our approach combines several recent innovations in the modelling of stand development, including (a) modelling of individual growth with biologically meaningful growth models and (b) modelling the relationship between size and growth of individuals within the population. Sequential, non‐destructive data on the growth of individuals over time, in combination with modern statistical computing techniques, can lead to major advances in the modelling of plant population development, providing powerful tools for exploring variation in individual growth and for testing a wide range of hypotheses.
Could plant‐feeding nematodes affect the competition between grass species during succession in grasslands under restoration management?
Authors: Verschoor B. C. , Pronk T. E. , De Goede R. G. M. , Brussaard L.
Published: March 2003

We examined the effects of plant‐feeding nematodes on competition between Holcus lanatus and Anthoxanthum odoratum. In the Drentse A nature reserve, the Netherlands, a relatively productive grassland, represented by H. lanatus, has gradually been replaced by a less‐productive community, represented by A. odoratum, after the application of fertiliser was stopped. Stressed plants are generally considered to be more sensitive to herbivory.

We hypothesized that plant‐feeding nematodes would exacerbate the competitive disadvantage of H. lanatus resulting from nutrient limitation. We compared performance in an adjusted De Wit replacement series with monocultures, grown in soil that was either treated or untreated with nematicides at both low and high nutrient supply.

The biomass production of both plant species was negatively affected by intra‐ and interspecific competition. Although H. lanatus was a stronger competitor than A. odoratum in mixed cultures, it was more sensitive to plant‐feeding nematodes and nutrient limitation. Nematodes and nutrient stress therefore reduced the competitive suppression of A. odoratum by H. lanatus. Low nutrient availability did not enhance the effect of plant‐feeding nematodes on plant growth and competition, indicating additive rather than synergistic effects on plant performance.

We conclude that plant‐feeding nematodes may contribute to species replacements in grasslands after fertilization has been stopped, albeit to a lesser extent than reduced nutrient availability. Plant species‐specific differences in tolerance to plant‐feeding nematodes in general, rather than host specificity of nematodes, are responsible for any effects.
Influences of fire history and topography on the pattern of a severe wind blowdown in a Colorado subalpine forest
Authors: Kulakowski Dominik , Veblen Thomas T.
Published: March 2003

In 1997, a major windstorm blew down over 10 000 hectares of subalpine forest in Routt National Forest in north‐western Colorado. We tested whether fire history and topographic variation, across the landscape, determined subsequent susceptibility to damage from this windstorm.

We combined dendrochronological techniques with a geographical information system (GIS) to examine the relationship between the effects of the blowdown and the spatial heterogeneity of the vegetation. We reconstructed the spatial fire history in a c. 4400 ha area by first identifying distinct patches in the landscape on aerial photographs, and then in the field by determining the disturbance history of each patch by dating fire scars, ages of post‐fire cohorts and releases of remnant trees.

Both topographic position and fire history contribute to susceptibility to wind damage. Stands at higher elevations, on easterly slopes and closer to ridges were most affected. Younger stands (i.e. more recently affected by stand‐initiating fires) were less affected particularly in areas affected by low–moderate severity blowdown (< 80% damage). The ecological effects of the very severe 1997 windstorm were mediated by the legacies of fires which occurred several centuries ago. Interactions between natural disturbances, such as fire and blowdown, lead to synergistic effects on forest dynamics, even when disturbance is infrequent.
Integrating lateral expansion into models of peatland development in temperate New England
Authors: Anderson Rebecca L. , Foster David R. , Motzkin Glenn
Published: March 2003

As peatlands form they create a temporal archive of community development, allowing the reconstruction of vegetation dynamics through the analysis of sediments and the development of detailed chronologies of successional change. Peatland formation occurs through two mechanisms: (i) terrestrialization, when a water body fills with sediments and peat; and (ii) paludification, the conversion of dry land to peatland. In temperate regions, where high summer temperatures may limit peat accumulation, general models of peatland development suggest that allogenic factors such as climate change control peatland development and that terrestrialization is the primary mechanism of formation.

This study evaluates this widely accepted model by comparing the developmental histories of three peatlands within the same climate region in New England in order to: (i) describe the development and timing of successional events among peatlands; (ii) document the roles of paludification and terrestrialization as developmental mechanisms; and (iii) evaluate the importance of climate change vs. autogenic factors in peatland development in this temperate region.

Basin morphometry, sediment stratigraphies, and chronologies of community change determined through radiocarbon dating indicate that peatland development at each site involved terrestrialization followed by paludification, with no apparent influence of broad‐scale climate change on the timing of these processes. Paludification was consistently initiated coincident with the consolidation of a shrub mat across each lake‐basin, and was controlled in extent and rate by the topography of the adjoining uplands. The timing of stratigraphic changes varied among sites, suggesting that autogenic factors associated with the accumulation of peat rather than regional climate change controlled development. These results provide the foundation for a model of temperate peatland development driven by autogenic factors and caution against the use of temperate peatland development as a proxy for climatic reconstruction.
Improving clinical outcome in bacteremia
Authors: Herchline Thomas , Gros Sheila
Published: March 2003

Bacteremia is associated with significant morbidity and mortality. There is wide variation in morbidity and mortality rates according to organism and predisposing conditions. Additionally, prompt administration of appropriate antimicrobial agents is associated with a decrease in mortality. Unfortunately, many bacteremic patients receive inappropriate or no antibiotics. Infectious disease consultation can decrease the number of patients receiving inappropriate initial therapy. ‘Quality standard for the treatment of bacteremia’ (Gross et al., 1994, Infection Control and Hospital Epidemiology15, 189–192) is a consensus paper; its purpose is to ‘improve the treatment of hospitalized patients with documented bacteremia by ensuring that they receive an antibiotic appropriate in light of the blood‐culture susceptibility of the pathogen isolated.’ A programme to assess the treatment of bacteremia can improve the quality of care with a modest commitment of additional resources. Many of the activities could be performed by a pharmacist, infection control practitioner, or pathologist. However, physician‐to‐physician communications are most likely to be successful. This programme should be considered a component of a hospital's quality‐improvement programme; either the hospital quality assurance or infection control committee could be responsible for the programme. We encourage adoption of the standard, and recommend prospective monitoring to include the choice of empiric antimicrobial agents.
Examining the assumptions of evidence‐based medicine
Authors: Norman Geoffrey R.
Published: March 2003

Evidence‐based medicine (EBM) has had enormous impact on clinical medicine, attracting both converts and detractors. The basic premise, that clinical decisions should be made on evidence which is as sound as possible, appears unassailable. Why, then, has the idea stimulated such controversy? In this article, I examine six assumptions of EBM, and point out how these assumptions are frequently open to challenge. Finally, I make specific recommendations for future activities to ensure that the strategy achieves an appropriate role in health care decision‐making. These include: (1) conducting research to establish the effectiveness of EBM; (2) incorporating (as they apparently are) more holistic perspectives on the nature of evidence; (3) moving (as they are) toward the use of expert reviews and away from a focus on the skilled individual practitioner; (4) examining the literature on continuing education to devise more appropriate dissemination strategies, including, specifically, educational influentials; and (5) making specific attempts at conciliation and seeking common ground with other schools of thought.
The 2‐year costs and effects of a public health nursing case management intervention on mood‐disordered single parents on social assistance
Authors: PhD(C) Maureen Markle‐Reid RegN MScN , PhD Gina Browne RegN , MSc Jacqueline Roberts RegN , PhD Amiram Gafni , PhD Carolyn Byrne RegN
Published: March 2003

Rationale, aims and objectives This randomized controlled trial was designed
to evaluate the 2‐year costs and effects of a proactive, public health nursing case
management approach compared with a self‐directed approach for 129 single parents
(98% were mothers) on social assistance in a Canadian setting. A total of
43% of these parents had a major depressive disorder and 38% had
two or three other health conditions at baseline. Methods Study participants
were recruited over a 12 month period and randomized into two groups: one receiving
proactive public health nursing and one which did not. Results At 2 years,
69 single parents with 123 children receiving proactive public health nursing (compared
with 60 parents with 91 children who did not receive public health nursing services)
showed a slightly greater reduction in dysthymia and slightly higher social adjustment.
There was no difference between the public health and control groups in total per
parent annual cost of health and support services. However, costs were averted due
to a 12% difference in non‐use of social assistance in the previous 12 months
for parents in the public health nursing group. This translates into an annual cost
saving of $240 000 (Canadian) of costs averted within 1 year for every 100 parents.
Conclusions In the context of a system of national health and social insurance, this study supports the fact that it is no more costly to proactively service this population of parents on social assistance.
Quantitative evaluation of prostatectomy for benign prostatic hypertrophy under a national health insurance law: a multi‐centre study
Authors: PhD D. Pilpel , MPH A. Porath MD , PhD A. Peleg
Published: March 2003

Assessing regional variation between various medical centres in diagnostic and surgical processes is an approach aimed at evaluating the quality of care. This study analyses the differences between eight medical centres in Israel, where all citizens are covered by medical insurance, through the National Health Insurance Law (NHIL). The analysis refers to the diagnostic process, type of surgery and immediate post‐surgical complications associated with prostatectomy for benign prostatic hypertrophy (BPH), which is the most frequent surgical procedure performed on men aged 50+. The study sample was comprized of 261 consecutive prostatectomy patients operated on in eight Israeli medical centres (MC), located in various parts of the country, between November 1996 and April 1997. Co‐operation with participating directors of surgical wards was obtained after confidentiality of information had been assured. Surgeons in selected departments abstracted data routinely recorded in the patient’s file and filled‐out a standard one‐page questionnaire. The following items were included: age, the presence of accompanying chronic diseases, preoperative tests, type of operation, and post‐surgical complications. In the various MCs 32.6% of the patients underwent more than five preoperative tests ranging from 8.9% to 88.9% (<0.01). Assessment of kidney and bladder normality ranged from 75% to 100% (P
< 0.01). The rate of patients whose prostatic symptoms (I‐PSS) were assessed ranged
from 0% to 79% (P < 0.01). There were also differences
in severity of prostatism between the MCs, with severe symptoms ranging from 54.0%
to 89.3% (P < 0.05), for type of operation performed (for ‘open’
prostatectomies, 35.4% to 68.0%, P < 0.01) and post‐operative
complications (19.0% to 41.6%, P = 0.07). After controlling for case‐mix, type of operation was the most important predictor for post‐surgical complications. MCs with low volume of surgeries had a higher rate of postoperative complications. We conclude that diagnostic and type of operation and post‐surgical complications differed between various MCs. Participating surgeons were willing to fill out a one‐page standard questionnaire from data routinely recorded in patients’ files.
The effect of participation in a weight loss programme on short‐term health resource utilization
Authors: FRCPC Carl van Walraven MD MSc , FRCPC Robert Dent MD
Published: March 2003

Obese people consume significantly greater amounts of health resources. This study set out to determine if health resource utilization by obese people decreases after losing weight in a comprehensive medically supervized weight management programme. Four hundred and fifty‐six patients enrolled in a single‐centred, multifaceted weight loss programme in a universal health care system were studied. Patient information was anonymously linked with administrative databases to measure health resource utilization for 1 year before and after the programme. Mean body mass index (BMI) decreased by more than 15%. The mean annual physician visits (pre = 9.6, post = 9.4) did not change significantly after the programme. However, patients saw a significantly fewer number of different physicians per year following the programme (pre = 4.5, post = 3.9; P < 0.001). Mean annual number of emergency visits (pre = 0.2; post = 0.2) and hospital admissions (pre = 0.05; post = 0.08) did not change. Neither baseline BMI, nor its change during the programme, influenced changes in health resource utilization. Our study suggests that weight loss in a supervized weight management programme does not necessarily decrease short‐term health resource utilization. Further study is required to determine if patients who maintain their weight loss experience a decrease in health utilization.
Clinical governance: vision or mirage?
Authors: Goodman Neville W.
Published: March 2003

Clinical governance was intended to ensure clinical quality in the National Health Service. Its first full description, in the British Medical Journal in 1998,
seemed to some to be more rhetoric than substance. Now, 3 years on, its proponents
believe it is starting to achieve its purpose. The British Medical Journal has again published a paper, this time subtitled ‘turning vision into reality’. Expectations might have been that this paper would present evidence of how clinical governance is changing practice to ensure quality, but analysis of the paper shows that it does little more than repeat the rhetoric of the earlier description. It describes how clinical governance might be organized and what it might do, but not what it has done. Its authors repeat the idea that everyone can be ‘the best’ and achieve ‘excellence’, which is not reality at all. Anyone introducing a new method of managing the National Health System has the same obligation as those who introduce new treatments to provide evidence that the method works, and that the financial and non‐financial costs are not too high. The new paper fails to provide that evidence.
The role of health informatics in clinical audit: part of the problem or key to the solution?
Authors: Georgiou Andrew , Pearson Michael
Published: March 2003

The concepts of quality assurance (for which clinical audit is an essential part), evaluation and clinical governance each depend on the ability to derive and record measurements that describe clinical performance. Rapid IT developments have raised many new possibilities for managing health care. They have allowed for easier collection and processing of data in greater quantities. These developments have encouraged the growth of quality assurance as a key feature of health care delivery. In the past most of the emphasis has been on hospital information systems designed predominantly for the administration of patients and the management of fin‐ancial performance. Large, hi‐tech information system capacity does not guarantee quality information. The task of producing information that can be confidently used to monitor the quality of clinical care requires attention to key aspects of the design and operation of the audit. The Myocardial Infarction National Audit Project (MINAP) utilizes an IT‐based system to collect and process data on large numbers of patients and make them readily available to contributing hospitals. The project shows that IT systems that employ rigorous health informatics methodologies can do much to improve the monitoring and provision of health care.
The evidence base for clinical governance
Authors: Thomas MB ChB, MRCP Matt
Published: March 2003

Rationale, aims and objectives Clinical governance has been advanced
as a mechanism for continuous quality improvement within the UK National Health Service
(NHS). This study aimed to assess whether evidence exists to support this claim.
Methods A Medline search for evidence to link the introduction of clinical
governance to improvements in the quality of health care was conducted. Results Of
the 335 papers retrieved initially, 114 were potentially relevant to the question,
but only 10 attributed changes in quality to clinical governance directly. Of these,
only three attempted to provide data to support the assertion. Conclusion No sound evidence currently exists to support the claim that clinical governance will increase service quality and moves towards its implementation must therefore be questioned.
If not evidence, then what? Or does medicine really need a base?
Authors: Upshur Ross E. G.
Published: March 2003

This essay analyses the concept of ‘base’ in relation to its use in evidence‐based medicine (EBM). It evaluates the extent to which evidence provides a sufficient base for health care to rest and discusses whether medicine needs a base, and, if so, what are the other possible candidates. This paper will argue that EBM is linked epistemologically to the theory of foundationalism and shows how important criticisms of EBM emerge from anti‐foundationalist epistemologies and interpretive frameworks. Drawing from recent writings in the philosophy of science, it is argued that there is a need to see multiple perspectives relevant to the practice and understanding of medicine.
The rising cost of health care: can demand be reduced through more effective health promotion?
Authors: Phillips Peter
Published: March 2003

The cost of health care continues to rise in the face of an apparently insatiable demand. Unless the actual need for health care can be reduced to manageable levels, the financial burden will probably become economically unacceptable. Although some illnesses are unavoidable, others that are largely due to unhealthy lifestyles are preventable. Circulatory diseases, diabetes and some cancers, which are major causes of morbidity and mortality in western societies, are strongly linked to physical inactivity, psychological stress, unhealthy eating, obesity and smoking. There is ample evidence that promotion of healthy lifestyles, including physical activity, healthy eating and non‐smoking, are effective for the primary and secondary prevention of these diseases. Although there are examples of successful public health programmes that have encouraged more healthy lifestyles and reduced the burden of disease, we need to be much more effective in putting theory into practice. In order to improve the health of the nation and to prevent the economy being overwhelmed by the increasing demand for health care, we need a change of mindset from a consumerist approach to an acceptance of personal and corporate responsibility for more healthy lifestyles. Widespread collaboration among health care agencies, private and public utilities, the entertainment industry and the communications media will be necessary in order to provide the necessary incentives for lifestyle changes.
Waiting for scheduled services in Canada: development of priority‐setting scoring systems
Authors: Noseworthy T. W. , McGurran J. J. , Hadorn D. C. ,   the Steering Committee of the Western Canada Waiting List Project
Published: March 2003

Rationale, aims and objectives An Achilles’ heel of Canadian Medicare is long waits for elective services. The Western Canada Waiting List (WCWL) project is a collaboration of 19 partner organizations committed to addressing this issue and influencing the way waiting lists are structured and managed. The focus of the WCWL project has been to develop and refine practical tools for prioritizing patients on scheduled waiting lists.

Methods Scoring tools for priority setting were developed through extensive clinical input and highly iterative exchange by clinical panels constituted in five clinical areas: cataract surgery; general surgery procedures; hip and knee replacement; magnetic resonance imaging (MRI) scanning, and children's mental health. Several stages of empirical work were conducted to formulate and refine criteria and to assess and improve their reliability and validity. To assess the acceptability and usability of the priority‐setting tools and to identify issues pertaining to implementation, key personnel in the seven regional health authorities (RHAs) participated in structured interviews. Public opinion focus groups were conducted in the seven western cities.

Results Point‐count scoring systems were constructed in each of the clinical areas. Participating clinicians confirmed that the tools offered face validity and that the scoring systems appeared practical for implementation and use in clinical settings. Reliability was strongest for the general surgery and hip and knee criteria, and weakest for the diagnostic MRI criteria. Public opinion focus groups endorsed wholeheartedly the application of point‐count priority measures. Regional health authorities were generally supportive, though cautiously optimistic towards implementation.

Conclusions While the WCWL project has not ‘solved’ the problem of waiting lists and times, having a standardized, reliable means of assigning priority for services is an important step towards improved management in Canada and elsewhere.
Dexamethasone treatment increases susceptibility of rainbow trout, Oncorhynchus mykiss (Walbaum), to infections with Gyrodactylus derjavini Mikailov
Authors: Lindenstrøm  , Buchmann
Published: March 2003

The parasite population dynamics of a Danish isolate of Gyrodactylus derjavini Mikailov 1975 on immunosuppressed fry of rainbow trout, Oncorhynchus mykiss (Walbaum), were investigated and compared with immunocompetent fry. Immunosuppression was induced 14 days prior to infection by intraperitoneal injections of dexamethasone (fluoro‐methyl‐prednisolone). Treated and untreated fish were infected by cohabitation with Gyrodactylus‐infected donorfish, carrying 4‐week‐old infections. Initial infections did not differ between the two groups. However, parasite populations increased significantly faster and reached significantly higher levels in the dexamethasone‐treated group from day 13 post‐exposure and during the following 3 weeks when compared with the untreated group. Microhabitat distribution of parasites on the two host groups differed from day 20 post‐exposure, which could indicate a different host response to infection. Changes in the density of superficial mucous cells in the caudal fins were investigated during the course of infection. No differences in mucous cell density between untreated and dexamethasone‐treated groups were found.
Survival, persistence and proliferation of Vibrio anguillarum in juvenile turbot, Scophthalmus maximus (L.), intestine and faeces
Authors: Olsson  , Jöborn  , Westerdahl  , Blomberg  , Kjelleberg  , Conway
Published: March 2003

The aim of this study was to determine whether orally administered V. anguillarum cells could survive passage through the intestinal tract of feeding turbot, and thereafter, proliferate in the released faeces. In addition, the growth of the pathogen in turbot faeces in the presence of a Carnobacterium sp. with inhibitory effects against a number of bacterial fish pathogens was studied. It was found that V. anguillarum cells survived the acidic environment of the stomach for several hours, persisted in the intestine and readily proliferated in the released faeces. The antagonistic Carnobacterium sp. inhibited the growth of V. anguillarum during co‐culture in turbot faecal extracts. From the results, it was concluded that the turbot intestinal tract and faeces can serve as an enrichment site for V. anguillarum, and the use of intestinal bacteria with antagonistic activity against vibrios may be used to reduce the load of fish pathogenic vibrios in turbot hatcheries.
Localization of purified surface molecules (lipopolysaccharide and A‐protein) from Aeromonas salmonicida in the kidney and spleen from Atlantic salmon, Salmo salar L.
Authors: Stensvåg K. , Arnesen S. M. , Bøgwald J. , Jørgensen T. Ò.
Published: March 2003

Lipopolysaccharide (LPS) and A‐layer protein purified from Aeromonas salmonicida were administered intravenously in Atlantic salmon, Salmo salar L., either alone or in combination. Tissues from each organ were examined by immunohistochemical techniques, using a polyclonal antiserum against A‐protein and a monoclonal antibody against LPS. When given simultaneously, the antigens seemed to be taken up by different cells in both the head and trunk kidney. The most striking finding was that A‐protein was located in epithelial cells in renal proximal tubules, in contrast to LPS, which was not detected in this location. The amount of A‐protein in the tissue increased with time until 2 h after injection. Autoradiography of SDS polyacrylamide gel electrophoresis of head kidney homogenates showed that in vivo processing of A‐protein coupled to iodinated tyramine cellobiose (125I‐TC‐A‐protein) was completed within 24 h, in contrast to LPS, which was maintained in tissues. The findings of the present study suggest that cells of the head kidney of Atlantic salmon are capable of taking up and processing the A‐protein.
Necrotic myositis of rainbow trout, Oncorhynchus mykiss (Walbaum): proteolytic characteristics of a crude extracellular preparation from Flavobacterium psychrophilum
Authors: Ostland V E , Byrne P J , Hoover G , Ferguson H W
Published: March 2003

A crude extracellular preparation (CEP) from a strain of Flavobacteriumpsychrophilum recovered from a case of necrotic myositis affecting rainbow trout was capable of causing severe muscle necrosis in rainbow trout following intramuscular injection. Cell wall‐associated preparations, however, were unable to produce similar lesions in experimentally injected fish. The CEP degraded gelatin and type II collagen but not type I or type IV collagen. Furthermore, the CEP did not degrade 2‐furanacryloyl‐
l‐leucylglycyl‐
l‐prolyl‐alanine (FALGPA), chondroitin sulphates A, B or C, heparan sulphate, keratan sulphate, hyaluronic acid, elastin or rainbow trout erythrocytes. The addition of the protease inhibitors 1,10‐phenanthroline, ethylenediamine‐tetraacetic acid (EDTA) and EGTA to the CEP halted its ability to degrade gelatin in vitro and to produce muscle necrosis in rainbow trout in vivo. In vitro and in vivo activity was restored following the addition of 1 m
m zinc chloride to the protease inhibitor‐treated CEP, suggesting that this strain of F. psychrophilum secretes a protein complex with zinc metalloprotease‐like activity. This protein complex, therefore, appears to be involved in the pathogenesis of necrotic myositis in rainbow trout.
Mass mortality associated with a Sphaerospora‐like myxosporidean infestation in juvenile cobia, Rachycentron canadum (L.), marine cage cultured in Taiwan
Authors: Chen S‐C , Kou R‐J , Wu C‐T , Wang P‐C , Su F‐Z
Published: March 2003

Cultured cobia, Rachycentron canadum, of 45–80 g exhibited anaemia and ascites, and a mottled red and grey, extremely enlarged kidney with cream‐coloured patches or spherical nodules. Cumulative mortality was about 90% within 1 month. Extrasporogonic or sporogonic stages of a myxosporean appeared in the blood, glomerulus, renal tubules and renal interstitium. The renal tubules were the main target tissue of the parasite and were completely occluded by sporogonic pseudoplasmodia at various degrees of maturity. Many sporogonic stages were attached to the brush border of the epithelium of the renal tubules. Mature spores were seen in the lumen of the tubules. They were elongated or spherical with numerous refractile granules in the cytoplasm. The polar filament formed 3–5 coils. No bacteria or viruses were isolated from the diseased fish. Based on the results of microbiological, histopathological and electron microscopical examinations, the cobia disease was believed to be caused by a Sphaerospora‐like myxosporean. This is the first report of a myxosporean in cobia in aquaculture.
A combined cell‐culture and RT–PCR method for rapid detection of piscine nodaviruses
Authors: Iwamoto T , Mori K , Arimoto M , Nakai T
Published: March 2003

A rapid method to detect piscine nodaviruses, the causal agents of viral nervous necrosis (VNN), at low virus levels is described. The reverse transcription–polymerase chain reaction (RT–PCR) technique required 104–105 TCID50 for detection of four strains representing different genotypes of piscine nodavirus: striped jack nervous necrosis virus (SJNNV), redspotted grouper nervous necrosis virus (RGNNV), tiger puffer nervous necrosis virus (TPNNV) and barfin flounder nervous necrosis virus (BFNNV). All the genotypic variants were isolated at the lowest titre (100 TCID50) by the E‐11 cell line, a clone derived from the SSN‐1 cell line, but it took approximately 10 days until the cytopathic effect (CPE) appeared in cells inoculated at low virus levels. When the virus was inoculated at various concentrations in E‐11 cells and incubated at 20 or 25 °C, cells inoculated previously with virus at a dose of 100 TCID50 became positive within 48 h incubation in the RT–PCR test. The present combined procedure of cell‐culture and RT–PCR techniques will be useful as a rapid and convenient method to detect infective viral particles from asymptomatic carriers or samples with low virus levels.
Water temperature regimes affect cataract development in smolting Atlantic salmon, Salmo salar L.
Authors: Bjerkås E , Bjørnestad E , Breck O , Waagbø R
Published: March 2003

The effect of fluctuation in water temperature during the freshwater rearing stage on cataract development in Atlantic salmon was investigated. Presmolts were exposed to either constant low or high temperatures, or high temperature with cold‐water fluctuations. Temperature fluctuations caused the fastest growth rate and most severe cataracts, whilst low temperature resulted in slow growth and minor cataracts. The fish were then individually marked and maintained together in a seawater net pen for 7 months. Cataract progressed in all groups, fish from the low temperature group showed the fastest subsequent growth, and developed cataracts to the same degree as fish from the other groups. There were no statistically significant differences in selenium‐dependent glutathione peroxidase levels in pooled samples of aqueous humour, lens and plasma from fish with or without cataract, except from the last freshwater samples, where cataractous fish showed lower plasma activity. Plasma cortisol and glucose levels did not differ, nor did whole eye riboflavin levels. Higher concentrations of some free amino acids in whole eyes were found in fish with cataract. This study shows that fluctuation in water temperature may cause both increased growth rate and cataract development in Atlantic salmon and that cataract development initiated in the freshwater rearing phase continues after transfers to seawater.
Molecular cloning of Yersinia ruckeri aroA gene: a useful taxonomic tool
Authors: Yugueros J , Temprano A , Luengo J M , Naharro G
Published: March 2003

The aroA gene of Yersinia ruckeri, which encodes 5‐enolpyruvylshikimate 3‐phosphate (EPSP) synthase was cloned by complementation of the aroA mutation in Escherichia coli AB2829 by using pUC18 plasmid as a vector. Nucleotide sequence of the aroA gene revealed an open reading frame of 427 amino acids showing a high degree of homology to other bacterial AroA proteins. A pair of primers with 23 and 20 nucleotides were selected from the 5′ and 3′ termini, respectively, and formed the basis of a specific polymerase chain reaction (PCR) assay. A 1165‐bp deoxyribonucleic acid (DNA) fragment was amplified from all lysed Y. ruckeri strains. An identical size fragment was also amplified from lysed Y. pseudotuberculosis, Y. aldovae, Salmonella enteritidis and E. coli, but not from other enterobacteria. AluI restriction fragment length polymorphism (RFLP) of the PCR amplified products allowed for differentiation between Y. ruckeri and the other bacteria. Specificity and sensitivity make this PCR assay a useful method for rapid identification and diagnosis of Y. ruckeri infections.
Conjugation of isometamidium chloride to antibodies and the use of the conjugate against the haemoflagellate, Cryptobia salmositica Katz, 1951: an immuno‐chemotherapeutic strategy
Authors: Ardelli B F , Woo P T K
Published: March 2003

The trypanocidal drug isometamidium chloride (Samorin) was conjugated to polyclonal and monoclonal antibodies produced against the pathogenic haemoflagellate Cryptobia salmositica. Under in vitro conditions the unconjugated drug normally accumulates rapidly in the kinetoplast in the parasite; however, once it was conjugated to antibodies (either polyclonal or monoclonal) it was found throughout the parasite. Isometamidium conjugated to polyclonal antibodies lysed C. salmositica under in vitro conditions, but parasites were not agglutinated. In contrast, isometamidium conjugated to monoclonal antibodies (against a 200 kDa surface membrane glycoprotein) did not lyse C. salmositica, but parasites were agglutinated. Because of the low efficacy of the monoclonal conjugate against the parasite in vitro, its cryptobiocidal effect was not evaluated further. The infectivity of C. salmositica (incubated either in culture medium or whole blood) was reduced in fish after in vitro exposure to isometamidium conjugated to polyclonal antibodies. Parasitaemias were reduced in infected chinook salmon, Oncorhynchus tshawytscha, after treatment with isometamidium conjugated to polyclonal antibodies.
Quantitative real time PCR for the measurement of white spot syndrome virus in shrimp
Authors: Durand S V , Lightner D V
Published: March 2003

Quantitative real time PCR, recently developed in molecular biology, is applied in this paper to quantify the white spot syndrome virus (WSSV) in infected shrimp tissue. The WSSV content in moribund shrimp of all species tested (Penaeus stylirostris, P. monodon, P. vannamei) ranged from 2.0 × 104 to 9.0 × 1010 WSSV copies μg–1 of total DNA (n=26). In whole moribund post‐larvae, 4.3 × 109 WSSV copies μg–1 of DNA were detected which is equivalent to 5.7 × 1010 WSSV copies g–1 of post‐larvae. The comparison of WSSV content between different tissues showed that muscle and hepatopancreas tissues contained 10 times less virus than gills, pleopods and haemolymph. With inocula of known virus content, bioassays by immersion challenge showed that a minimum of five logs of WSSV copies was necessary to establish disease in the challenged shrimp. In contrast, five logs of WSSV copies injected into shrimp muscle produced a LT‐50 of 52 h. This real time polymerase chain reaction (PCR) technique is sensitive (four copies), specific (negative with DNA from shrimp baculoviruses and parvoviruses), dynamic (seven logs) and easy to perform (96 tests in <4 h).