bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduced colonization capacity in fragmented populations of wind‐dispersed grassland forbs
Authors: Soons Merel B. , Heil Gerrit W. 
Published: March 2003

Summary

Habitat fragmentation as a result of intensification of agricultural practices decreases the population size and increases the site productivity of remnant populations of many plant species native to nutrient‐poor, species‐rich grasslands. Little is known about how this affects the colonization capacity of populations, which is highly important for regional species survival. We studied the effects on four wind‐dispersed forbs that represent two major dispersal strategies in grasslands: Cirsium dissectum and Hypochaeris radicata, which have plumed seeds and are adapted to long‐distance dispersal by wind, and Centaurea jacea and Succisa pratensis, which have plumeless seeds and are adapted to only short‐distance dispersal by wind.
Colonization capacity decreased with decreasing population size. This was due to lower seed germination ability in all species, and a lower seed production and a narrower range of seed dispersal distances in the species with plumed seeds. Inbreeding depression is the most likely cause of this. We found no evidence for a stronger selection for reduced dispersal in smaller populations.
Increasing site productivity changed the colonization capacity of all species. The capacity for colonization of nearby sites increased, due to higher seed production and seed germination ability, but the capacity for colonization of distant sites decreased, due to a lower long‐distance dispersal ability.
Seed dispersal ability and germination ability were negatively correlated in the species with plumeless seeds, but not in the species with plumed seeds. The dispersal ability of individual plumed seeds remained constant under changes in population size and site productivity. This indicates a strong selection pressure for long‐distance dispersal ability in these species.
When habitat fragmentation results in a simultaneous decrease in population size and increase in site productivity, both the local survival probability and the colonization capacity of remnant populations of wind‐dispersed grassland forbs are likely to be severely reduced. This increases regional extinction risks of the species.
Unapparent virus infection and host fitness in three weedy grass species
Authors: Remold Susanna K. 
Published: March 2003

Summary

The effects of pathogens on natural plant populations are poorly understood, in part because many cause few overt symptoms. I investigated the correlations between the incidence of barley yellow dwarf viruses (BYDVs) and total panicle length, a fitness proxy, in three apparently unaffected hosts, Bromus hordeaceus (Pooideae), Setaria viridis and Setaria lutescens (Panicoideae).
Whereas B. hordeaceus individuals did not differ in fitness with respect to infection, average fitness of infected S. viridis was approximately half that of uninfected individuals, and in one out of two years, infected S. lutescens had approximately 25% higher fitness. Variability among hosts appears to contribute more than variability among BYDV serotypes to the pattern of infection outcomes.
These correlations suggest that the relationship between BYDVs and these co‐occurring host species ranges from antagonism to mutualism. If so, BYDVs can act as agents of selection in natural populations in which the symptoms of infection are unapparent.
The results also demonstrate that infections can be unapparent due to large trait variance rather than small mean effects. Because high trait variances are widespread in many natural populations, unapparent infections may be common in wild plant communities.
Litter quality and interactive effects in litter mixtures: more negative interactions under elevated CO2?
Authors: Hoorens Bart , Aerts Rien , Stroetenga Martin 
Published: March 2003

Summary

The decomposition rate of litter mixtures can depend on interactions between compounds in the component species, i.e. in litter chemistry. Differences in litter N concentration are likely to lead to positive interaction (i.e. faster than expected decomposition) and differences in phenolic concentrations to a negative interaction. These interactions may become less positive (or more negative) when the litter is produced under elevated atmospheric CO2 concentrations.
We measured respiration rates of litter from two contrasting species pairs, produced under ambient and elevated CO2.
As expected, mixtures of Calamagrostis epigejos and Vicia lathyroides, which differed strongly in litter N concentration, decomposed faster than expected, but the interaction disappeared under elevated CO2.
Despite the large difference in litter N concentration between Sphagnum recurvum and Carex rostrata, no interaction was observed in the ambient CO2 litter mixtures, and under elevated CO2, there was an unexpected positive interaction.
Interactions in litter mixtures can therefore change under elevated CO2, albeit not in a predictable manner, which would require correct prediction of species‐specific litter chemistry and its response to elevated CO2.
Are fungi necessary? How fungicides affect growth and survival of the orchid Lepanthes rupestris in the field
Authors: Bayman Paul , González Eduardo J. , Fumero José J. , Tremblay Raymond L. 
Published: March 2003

Summary

Mycorrhizal associations of tropical, epiphytic orchids have been studied in vitro, but the importance of the relationship has not been demonstrated in the field. We investigated the effect of fungicide treatment on seedlings and juveniles of the lithophytic orchid Lepanthes rupestris. As mycorrhizas, endophytes and pathogens coexist in orchids, fungicide treatment might have either a positive or negative effect on growth and survival of plants.
The experimental design included benomyl‐treated, propiconazole‐treated, and control plots. Each treatment consisted of about 140 2 × 2 cm plots divided among eight rocks, with one seedling or juvenile (occasionally two) per plot. Fungicides were applied every 2 weeks and plants were censused and measured every 3 months for 8–9 months.
Propiconazole‐treated plants had higher mortality, significantly fewer leaves, significantly fewer fungal colonies in their roots, and significantly fewer degraded pelotons than did control plants. Benomyl‐treated plants had significantly lower mortality than controls and significantly fewer fungi in leaves than control plants, and did not differ in number of degraded pelotons. There was little or no recruitment in any treatment.
Few potentially mycorrhizal fungi were isolated. Guignardia, Colletotrichum and Xylaria, which are generally endophytes, pathogens and/or saprotrophs, were more common. There was evidence of antagonism between Colletotrichum and Xylaria and between Colletotrichum and Guignardia.
Results suggest that fungi have both positive and negative effects on growth and survival of L. rupestris plants. However, conclusions about the importance of mycorrhizas are complicated by the simultaneous occurrence of a range of orchid–fungus interactions.
Evidence‐based medicine training in graduate medical education: past, present and future
Authors: Green Michael L. 
Published: March 2003

AbstractEvidence‐based medicine (EBM) training remains a challenge to educators, particularly in graduate medical education. In this article, I trace the history of EBM in American medical education, review traditional journal clubs and contrast them to free‐standing EBM curricula, petition for the advancement of integrated EBM teaching and propose an agenda for future work. Traditional journal clubs are unsuitable to teach evidence‐based decision making because of their exclusive focus on critical appraisal. In contrast, EBM curricula cover the identification, appraisal and application of evidence in the context of individual patient scenarios. The effectiveness of some recent efforts reflects increasing attention to curriculum development principles and scientific rigour. The integration of EBM training into residents’ established clinical venues offers theoretical educational advantages and confronts the challenge of practising EBM under the imperatives of ‘real time’ patient care. Initial responses to this formidable challenge show promise, but their feasibility and effectiveness remain to be explored. A more complete understanding of the epidemiology of residents’ emerging clinical questions will inform continued curriculum development in integrated EBM training.
Evaluation of clinical information systems. What can be evaluated and what cannot?
Authors: Bürkle, Thomas , Ammenwerth, Elske , Prokosch Hans‐Ulrich , Dudeck Joachim 
Published: March 2003

AbstractThe evaluation of clinical information systems is essential as they are increasingly used in clinical routine and may even influence patient outcome on the basis of reminder functions and decision support. Therefore we try to answer three questions in this paper: what to evaluate; how to evaluate; how to interpret the results. Those key questions lead to the discussion of goals, methods and results of evaluation studies in a common context. We will compare the objectivist and the subjectivist evaluation approach and illustrate the evaluation process itself in some detail, discussing different phases of software development and potential evaluation techniques in each phase. We use four different practical examples of evaluation studies that were conducted in various settings to demonstrate how defined evaluation goals may be achieved with a limited amount of resources. This also illustrates advantages, limitations and costs of the different evaluation methods and techniques that may be used when evaluating clinical information systems.
Coding diagnoses and procedures using a high‐quality clinical database instead of a medical record review
Authors: Walraven Carl van , Demers Sylvie V. 
Published: March 2003

AbstractA discharge abstract must be completed for each hospitalization. The most time‐consuming component of this task is a complete review of the doctors’ progress notes to identify and code all diagnoses and procedures. We have developed a clinical database that creates hospital discharge summaries. To compare diagnostic and procedural coding from a clinical database vs. the standard chart review by health records analysts (HRA). All patients admitted and discharged from general medical and surgical services at a teaching hospital in Ontario, Canada. Diagnostic and procedural codes were identified by reviewing discharge summaries generated from a clinical database. Independently, codes were identified by hospital health records analysts using chart review alone. Codes were compared with a gold standard case review conducted by a health records analyst and a doctor. Coding accuracy (percentage of codes in gold standard review) and completeness (percentage of gold standard codes identified). The study included 124 patients (mean length of stay 5.5 days; 66.4% medical patients). The accuracy of the most responsible diagnosis was 68.5% and 62.9% for the database (D) and chart review (C), respectively (P = 0.18). Overall, the database significantly improved the accuracy (D = 78.9% vs. C = 74.5%; P = 0.02) and completeness (D = 63.9% vs. C = 36.7%; P < 0.0001) of diagnostic coding. Although completeness of procedural coding was similar (D = 5.4% vs. C = 64.2%; P = NS), accuracy decreased with the database (D = 70.3% vs. C = 92.2%; P < 0.0001). Mean resource intensity weightings calculated from the codes (D = 1.3 vs. C = 1.4; P = NS) were similar. Coding from a clinical database may circumvent the need for HRAs to review doctors’ progress notes, while maintaining the quality of coding in the discharge abstract.
Reporting health care performance: learning from the past, prospects for the future
Authors: Mannion Russell , Davies Huw T. O. 
Published: March 2003

AbstractIn the USA, where public reporting of data on clinical performance is most advanced, comparative performance information, in the form of ‘report cards’, ‘provider profiles’ and ‘physician profiling’, has been published for over a decade. Many other countries are now following a similar route and are seeking to develop comparative data on health care performance. Notwithstanding the idiosyncratic nature of US health care, and the implications this has for the generalizability of findings from the USA to other countries, it is pertinent to ask what other countries can learn from the US experience. Based on a series of structured interviews with leading experts on the US health system, this article draws out the key lessons for other countries as they develop similar policies in this area. This paper highlights three concerns that have dominated the development of adequate measures in the USA, and that require consideration when developing similar schemes elsewhere. Firstly, the need to develop indicators with sound metric properties – high in validity and meaningfulness, and appropriately risk‐adjusted. Secondly, the need to involve all stakeholders in the design of indicators, and a requirement that those measures be adapted to different audiences. Thirdly, a need to understand the needs of end users and to engage with them in partnerships to increase the attention paid to measurement. This study concludes that the greatest challenge is posed by the desire to make comparative performance data more influential in leveraging performance improvement. Simply collecting, processing, analysing and disseminating comparative data is an enormous logistical and resource‐intensive task, yet it is insufficient. Any national strategy emphasizing comparative data must grapple with how to engage the serious attention of those individuals and organizations to whom change is to be delivered.
At what degree of belief in a research hypothesis is a trial in humans justified?
Authors: Djulbegovic Benjamin , Hozo Iztok 
Published: March 2003

AbstractRationale, aims and objectives Randomized controlled trials (RCTs) have
emerged as the most reliable method of assessing the effects of health care interventions
in clinical medicine. However, RCTs should be undertaken only if there is substantial
uncertainty about which of the trial treatments would benefit a patient most. The
purpose of this study is to determine the degree of uncertainty in a research hypothesis
before it can empirically be tested in an RCT. Methods We integrated arguments
from three independent lines of research – on ethics, principles of the design
and conduct of clinical trials, and medical decision making – to develop a
decision model to help solve the dilemma of under which circumstances innovative
treatments should be tested in an RCT. Results We showed that RCTs are
the preferable option to resolve uncertainties about competing treatment alternatives
whenever we desire reliable, undisputed, high‐quality evidence with a low likelihood
of false‐positive or false‐negative results. Conclusions When the expected benefit : risk ratio of a new treatment is small, an RCT is justified to resolve uncertainties over a wide range of prior belief (e.g. 10–90%) in the accuracy of the research hypothesis. Randomized controlled trials represent the best means for resolving uncertainties about health care interventions.
Do abnormal liver function tests predict inpatient imaging yield? An evaluation of clinical decision making
Authors: Rothschild Jeffrey M. , Khorasani Ramin , Hanson Richard W. , Fiskio Julie M. 
Published: March 2003

AbstractRationale, aims and objectives Diagnostic abdominal imaging is frequently performed in hospitalized patients to assess the cause of abnormal liver function tests (LFTs). We undertook this study to assess whether the extent and severity of LFTs abnormalities predicted the yield of inpatient imaging.Methods We retrospectively reviewed inpatients’ abdominal imaging studies performed for abnormal LFTs during a 27 month period. Imaging results were matched to LFTs performed during a 5 day collection window surrounding the image request date. Five LFTs were categorized by severity of abnormality and were then collapsed into three classes based on pathophysiology.Results Among 759 imaging studies completed for the indication of abnormal LFTs, 196 (26%) were positive (abnormal and explained the abnormal LFTs). Among the LFT classes, severity of laboratory test abnormality correlated with positive imaging examinations yield only for the transaminases: 18% for the normal–mildly abnormal transaminases compared with 31% for moderately–severely abnormal transaminases. The number of abnormal LFT classes per study correlated only slightly better: 21% of patients with none or one abnormal LFT class had a positive imaging study compared with 35% of patients with all three abnormal LFT classes.Conclusions The yield of inpatient abdominal imaging for abnormal LFTs correlates only weakly with both the severity and the extent of different abnormal LFTs. Further research is needed to define the optimal imaging strategies for evaluating inpatients with suspected hepatobiliary disease.
Development of a polymerase chain reaction (PCR) procedure for the detection of baculovirus associated with white spot syndrome (WSBV) in penaeid shrimp
Authors: Kim  , Kim  , Sohn  , Sim  , Park  , Heo  , Lee  , Lee  , Jun  , Jang  
Published: March 2003

AbstractThe causative viral agent was purified from diseased shrimp Penaeus japonicus with white spot syndrome (WSBV). Several hundred clones were obtained from libraries of the purified viral genomic DNA. According to the results of nucleotide sequence analysis, none of the WSBV clones showed considerable sequence homology with those of other known viruses, indicating that WSBV is a new virus causing a serious disease in shrimp. Based on the sequence data of WSBV genomic DNA, a pair of polymerase chain reaction (PCR) primers was designed. After 30 cycles of PCR amplification of viral genomic DNA extracted from WSBV, a single product of the expected size was detected. Southern blot hybridization confirmed that the amplified product was specific to the DNA of WSBV. The PCR system was able to detect 1 pg of WSBV DNA after 30 cycles, and efficiently amplify the target region of WSBV gene in the total nucleic acids extracted either from the diseased shrimp or hatchery shrimp with no signs of viral infection.
Development of improved PCR to prevent false positives and false negatives in the detection ofTetracapsula bryosalmonae, the causative agent of proliferative kidney disease
Authors: Morris D C , Morris D J , Adams A 
Published: March 2003

AbstractProliferative kidney disease (PKD) is an economically significant disease caused by the myxozoan parasiteTetracapsula bryosalmonae. Polymerase chain reaction (PCR) protocols using primers specific for the small subunit ribosomal RNA (18S rDNA) gene of the parasite enable detection, however, false positive and negative results can render detection inconclusive. In this study a decontamination protocol was developed, using hydroxylamine hydrochloride (H), to prevent false positives by blocking re‐amplification of carry‐over contaminants. A mimic molecule was also developed and used as a competitive internal standard coamplified with target DNA in PCRs, revealing both true and false negatives. The sensitivity of one new and two existing primer sets was assessed with all primers detecting DNA equivalent to at least eight parasite cells per gram of tissue. This improved PCR protocol canprovide more reliable testing forT. bryosalmonae.
Ribosomal DNA sequences indicate isolated populations of Ichthyophonus hoferi in geographic sympatry in the north‐eastern Pacific Ocean
Authors: Criscione C D , Watral V , Whipps C M , Blouin M S , Jones S R M , Kent M L 
Published: March 2003

AbstractInfections of Ichthyophonus hoferi, a cosmopolitan parasite of marine fish, have recently been reported in rockfish, Sebastes spp., from the north‐eastern Pacific. Because I. hoferi also infects Pacific herring, Clupea pallasi Valenciennes, and salmonids in this region, we wanted to determine if Ichthyophonus parasites from rockfishes, Pacific herring and chinook salmon, Oncorhynchus tshawytscha (Walbaum), were the same. Small subunit ribosomal deoxyribonucleic acid sequence data revealed two haplotypes that were fixed among host species in geographic sympatry, one from rockfish and the other from both Pacific herring and salmon. These isolated populations of Ichthyophonus could be part of the same species that are ecologically separated because of host behaviours, or they could be distinct species that are host specific. Dietary patterns of the hosts indicate that ecological separation among hosts is possible, but the presence of distinct species may better explain the observed Ichthyophonus haplotype association with host species.
An alkaline phosphatase‐based method for the detection of infectious salmon anaemia virus (ISAV) in tissue culture and tissue imprints
Authors: Wilson L , McBeath S J , Adamson K L , Cook P F , Ellis L M , Bricknell I R 
Published: March 2003

AbstractCurrently, the presence of infectious salmon anaemia virus (ISAV) is often detected in Atlantic salmon by the use of an indirect fluorescent antibody test. This test is limited by the poor stability of fluorescein isothiocyanate which fades after about a week in storage, preventing the development of stained archive material as a reference source. One possible alternative would be the use of immunohistochemical staining methods to detect ISAV. An immunohistochemical method is presented that uses alkaline phosphatase‐conjugated antibodies and Vector® Red as a substrate, to detect ISAV in kidney imprints. This paper also describes a procedure where Bouin's fluid is used to successfully inhibit endogenous alkaline phosphatase in tissue samples, prior to immunohistochemical processing. This method provides a stable stain that can be read for many weeks after staining or archived for future reference.
Investigation of media formulations promoting differential antigen expression by Photobacterium damsela ssp. piscicida and recognition by sea bass, Dicentrarchus labrax (L.), immune sera
Authors: Bakopoulos V , Pearson M , Volpatti D , Gousmani L , Adams A , Galeotti M , Dimitriadis G J 
Published: March 2003

Abstract Photobacterium damsela ssp. piscicida (Phdp) isolates were grown in various bacteriological media, in eukaryotic cell culture media and in the presence of fish cells (resembling some aspects of in vivo growth environments). Bacterial cells, extracellular products (ECPs) and crude capsular polysaccharide were isolated and analysed by electrophoresis and Western blot using sea bass sera. Growth in bacteriological media conserved the synthesis of cell and extracellular components when these were compared with those prepared under near‐in vivo growth conditions. In fact, synthesis of a larger range of cell components was induced after growth in bacteriological media. Certain media based on yeast extract and peptones from various sources and a specific salt formulation induced the synthesis of novel cell components at approximately 21.3 and 14 kDa. These antigens were recognized by sea bass sera collected after natural pasteurellosis outbreaks and other sea bass sera raised against live or inactivated Phdp cells. The ECPs of the pathogen were not good immunogens in their soluble form despite various treatments prior to immunization. The results are discussed with respect to vaccine development.