bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation in the risk of being wounded: an overlooked factor in studies of invertebrate immune function?
Authors: Plaistow S. J. , Outreman Y. , Moret Y. , Rigaud T. 
Published: May 2003

AbstractIn invertebrates, wounding can trigger an immune response, and will often expose organisms to parasites and pathogens. Here we show that in the amphipod Gammarus pulex, wounding abundance is negatively correlated with PhenolOxidase activity (a major component of the invertebrate immune response), and that the occurrence and abundance of wounding is extremely high and varies significantly between five natural populations. In some populations the prevalence and abundance of wounds also varied between sexes. Given that, using and maintaining an efficient immune system is costly, we suggest that the frequency of wounding may be an important selective pressure influencing an organism's optimal investment in immune defences.
Conspicuous extra‐floral nectaries are inducible in Vicia faba
Authors: Mondor Edward B. , Addicott John F. 
Published: May 2003

AbstractMutualistic interactions are dynamic associations that vary depending on the costs and benefits to each of the interacting parties. Phenotypic plasticity in mutualistic interactions allows organisms to produce rewards to attract mutualists when the benefits of their presence outweigh the costs of producing the rewards. In ant–plant defensive mutualisms, defences are indirect as plants produce extra‐floral nectaries (EFN) to attract predatory ants to deter herbivores. Here we demonstrate that in broad bean, Vicia faba, the overall number of EFNs on a plant increases dramatically following leaf damage. In two damage treatments, removal of: (1) one‐third of one leaf in a single leaf pair or (2) one‐third of both halves of a single leaf pair, resulted in a 59 and 106% increase in the number of EFNs on the plants, respectively, over 1 week. We suggest that the increased production of visually conspicuous EFNs is an adaptive inducible response, to attract predatory arthropods when risk of herbivory increases.
Covert infections as a mechanism for long‐term persistence of baculoviruses
Authors: Burden John P. , Nixon Clare P. , Hodgkinson Alison E. , Possee Robert D. , Sait Steven M. , King Linda A. , Hails Rosemary S. 
Published: May 2003

AbstractThe prevalence of pathogens in wild populations has often been estimated by the appearance of overt symptoms in the host, and this is typically used as the sole gauge of the impact of the pathogen on host dynamics. However, the development of molecular methods has increased the sensitivity with which we can detect asymptomatic infections. Baculoviruses are insect pathogens that, like many microparasites, are usually only found when their hosts reach outbreak densities, when a disease epizootic occurs. Conventional wisdom is that the long‐term persistence of baculoviruses relies on their survival in the external environment in the form of occlusion bodies. These are proteinaceous matrices in which the virus particles are embedded, and which provide a degree of protection from UV irradiation. However, Mamestra brassicae has also been shown to harbour a persistent, non‐lethal baculovirus infection (M. brassicae nucleopolyhedrovirus) in laboratory culture, which may represent another putative persistence mechanism. Here, we present evidence that such covert infections are also present and frequent in natural populations of the moth. The persistent infections were triggered into the lethal overt state by exposure to another baculovirus, and two closely related but different baculoviruses were subsequently identified as persistent infections within the populations sampled. These results have broad‐ranging implications for our understanding of host pathogen interactions in the field, in the use of pathogens as biocontrol agents, and in the evolution of virulence.
Interactions among mycorrhizae, atmospheric CO2 and soil N impact plant community composition
Authors: Johnson Nancy Collins , Wolf Julie , Koch George W. 
Published: May 2003

AbstractWe examined plant community responses to interactions between arbuscular mycorrhizal (AM) fungi and availability of atmospheric CO2 and soil N. Communities of 14 plant species were grown in mesocosms containing living or killed AM fungal inoculum, ambient or elevated atmospheric CO2 and low or enriched soil N. After one growing season, significantly different plant communities existed in the different treatments. Plant species richness was lowest in +N mesocosms and highest in +AM + CO2 mesocosms. At ambient CO2, AM fungi reduced richness but at elevated CO2 they increased it. This was caused by changes in mortality rates of several C3 forbs and may suggest that CO2 enrichment ameliorates the carbon cost of some AM symbioses. Soil moisture was higher in +CO2 mesocosms but +AM counteracted this effect. These results suggest that AM symbioses may be important mediators of plant community responses to anthropogenic CO2 and N enrichment.
Alternative male life‐history tactics as potential vehicles for speeding introgression of farm salmon traits into wild populations
Authors: Garant Dany , Fleming Ian A. , Einum Sigurd , Bernatchez Louis 
Published: May 2003

AbstractReleases of cultured organisms, such as farm Atlantic salmon (Salmo salar L.), threaten native biodiversity and the integrity of natural communities. Salmon escaping from sea farms, however, have relatively poor reproductive success, suggesting that the rate of spread of domesticated traits may be reduced. We now compare the relative reproductive success of males that mature precociously in freshwater (parr) and find that those of farm origin have higher breeding and fertilization success than wild and hybrid individuals. Specifically, hybrid parr had 57% and wild parr 25% the success of farm parr. Early maturing males could thus be important vehicles promoting introgression of domesticated and/or non‐native traits into wild populations and ultimately have long‐term impact on the genetic integrity of native populations.
Effects of altered resource consumption rates by one consumer species on a competitor
Authors: Abrams Peter A. 
Published: May 2003

AbstractNon‐mechanistic models of competition suggest that harming one of two competing species will increase the population density of the other. These models also suggest that any change in a fitness component of one competitor will make the densities of the two competitors change in opposite directions. However, models of competition that incorporate resource dynamics show that neither conclusion holds generally. Reducing the consumption abilities of one competitor may decrease the population size of the other by decreasing resource overexploitation by the first and thereby increasing its density. It is also possible for decreased consumption abilities of one species to increase the population densities of both species, when the increased density of the focal species is offset by its decreased ability to consume the main resources of its competitor. Finally, decreases in consumption may have the effects predicted by phenomenological models; a decrease in the focal species and an increase in its competitor. Unstable systems may exhibit more complicated patterns of changes in densities with changes in consumption rates. These counterintuitive effects depend on the presence of overexploitation of biotic resources, about which little is known. More generally, there have been few theoretical or empirical studies examining the indirect effects of changes in consumption rates of a focal species in a food web; these are termed ‘trait‐initiated indirect effects’. A better understanding of the potential consequences of altered consumption rates will be important for understanding biotic shifts in communities undergoing environmental change, and in using simple community modules to understand larger food webs.
Complexity and stability revisited
Authors: Jansen Vincent A. A. , Kokkoris Giorgos D. 
Published: May 2003

AbstractSince Robert May's work on random community matrices it has been known that stability tends to decrease with complexity. Recently, it was shown that this is not necessarily true in competitive ecosystems. We investigated the stability of random ecosystems and found that it can largely be predicted by simple matrix statistics such as the mean and the variance of the interaction coefficients. We use this to explain why stability can increase as well as decrease with complexity in ecological communities. We argue that the variance, and to a lesser extent the mean, of the interaction coefficients go a long way in explaining patterns in the stability of ecosystems.
Diversity in mussel beds at deep‐sea hydrothermal vents and cold seeps
Authors: Turnipseed M. , Knick K. E. , Lipcius R. N. , Dreyer J. , Van Dover C. L. 
Published: May 2003

AbstractRemarkably little is known about fundamental distinctions (or similarities) between the faunas of deep‐sea hydrothermal vents and seeps. Low species richness at vents has been attributed to the transient nature of vent habitats and to toxic effects of hydrogen sulphide and heavy metals in vent effluents. Seeps are arguably more stable and more chemically benign than vents. They have also been regarded as more diverse, but until now there has not been a rigorous test of this hypothesis. We evaluated diversity indices for invertebrates associated with mussel beds at six vents and two seeps and found that invertebrate diversity was significantly higher at seeps than vents, although some vent mussel beds supported nearly the same diversity as seep mussel beds. Lower diversity at vents may be a consequence of a greater physiological barrier to invasion at vents than at seeps. Diversity was lowest where spacing between vents was greatest, suggesting that risks of extinction as a result of dispersal‐related processes may contribute to the pattern of diversity observed at vents.
Effects of parasitoid fecundity and host resistance on indirect interactions among hosts sharing a parasitoid
Authors: Heimpel George E. , Neuhauser Claudia , Hoogendoorn Marlijn 
Published: May 2003

AbstractWe examine the effects of fecundity‐limited attack rates and resistance of hosts to parasitism on the dynamics of two‐host–one‐parasitoid systems. We focus primarily on the situation where one parasitoid species attacks two host species that differ in their suitability for parasitism. While all eggs allocated to suitable hosts develop into adult parasitoids, some of the eggs allocated to marginal host do not develop. Marginal hosts can therefore act as a sink for parasitoid eggs. Three‐species coexistence is favoured by low levels of parasitoid fecundity and by low levels of suitability of the marginal host. Our model also produces an indirect (+, −) interaction in which the suitable host can benefit from the presence of the marginal host, but the marginal host suffers from the presence of the suitable host. The mechanism driving the indirect (+, −) interaction is egg limitation of parasitoids incurred by allocating eggs to marginal hosts.
Multi‐predator effects across life‐history stages: non‐additivity of egg‐ and larval‐stage predation in an African treefrog
Authors: Vonesh James R. , Osenberg Craig W. 
Published: May 2003

AbstractThe effects of multiple predators on their prey are frequently non‐additive because of interactions among predators. When prey shift habitats through ontogeny, many of their predators cannot interact directly. However, predators that occur in different habitats or feed on different prey stages may still interact through indirect effects mediated by prey traits and density. We conducted an experiment to evaluate the combined effects of arboreal egg‐stage and aquatic larval‐stage predators of the African treefrog,Hyperolius spinigularis. Egg and larval predator effects were non‐additive – moreHyperoliussurvived both predators than predicted from their independent effects. Egg‐stage predator effects on aquatic larval density and size and age at hatching reduced the effectiveness of larval‐stage predators by 70%. Our results indicate that density‐ and trait‐mediated indirect interactions can act across life‐stages and habitats, resulting in non‐additive multi‐predator effects.
Disentangling biodiversity effects on ecosystem functioning: deriving solutions to a seemingly insurmountable problem
Authors: Naeem Shahid , Wright Justin P. 
Published: May 2003

AbstractExperimental investigations of the relationship between biodiversity and ecosystem functioning (BEF) directly manipulate diversity then monitor ecosystem response to the manipulation. While these studies have generally confirmed the importance of biodiversity to the functioning of ecosystems, their broader significance has been difficult to interpret. The main reasons for this difficulty concern the small scales of the experiment, a bias towards plants and grasslands, and most importantly a general lack of clarity in terms of what attributes of functional diversity (FD) were actually manipulated. We review how functional traits, functional groups, and the relationship between functional and taxonomic diversity have been used in current BEF research. Several points emerged from our review. First, it is critical to distinguish between response and effect functional traits when quantifying or manipulating FD. Second, although it is widely done, using trophic position as a functional group designator does not fit the effect‐response trait division needed in BEF research. Third, determining a general relationship between taxonomic and FD is neither necessary nor desirable in BEF research. Fourth, fundamental principles in community and biogeographical ecology that have been largely ignored in BEF research could serve to dramatically improve the scope and predictive capabilities of BEF research. We suggest that distinguishing between functional response traits and functional effect traits both in combinatorial manipulations of biodiversity and in descriptive studies of BEF could markedly improve the power of such studies. We construct a possible framework for predictive, broad‐scale BEF research that requires integrating functional, community, biogeographical, and ecosystem ecology with taxonomy.
Colonoscopic surveillance after curative colorectal resection: Results of an empirical surveillance programme
Authors: McFall M. R. , Woods W. G. A. , Miles W. F. A. 
Published: May 2003

AbstractIntroduction  Colonoscopic surveillance after colorectal cancer resection is widely practised despite little evidence that it improves survival. The optimum protocol for colonoscopic follow‐up after colorectal cancer resection has not yet been elucidated. We audited the outcome of an empirical colonoscopic follow‐up programme in a cohort of patients who underwent colorectal resection with a minimum of five years follow‐up to establish patterns of metachronous neoplasia and suitable surveillance intervals.Methods  The colonoscopic records, biopsy results and follow‐up details of patients diagnosed with colorectal cancer between June1990 and June1996 were reviewed. The number and type of metachronous neoplastic lesions diagnosed was recorded. Rates of development of new neoplasms were estimated by calculating the time from operation to their first discovery. Factors predictive of further development of polyps or cancer were sought. Results were compared to published reports of intensive follow‐up programmes.Results  Seven hundred and ninety‐eight patients underwent colorectal resection with curative intent during the study period. 226 patients had one or more follow‐up colonoscopies (mean time post resection 48.8 months). In total 352 colonoscopies, encompassing 1437 patient years of surveillance, were performed. Nine metachronous cancers in eight patients, five of which were asymptomatic were diagnosed by colonoscopy at a mean of 63 months. Three asymptomatic recurrences were diagnosed but all were inoperable. 70 (31%) patients had adenomatous polyps diagnosed after a mean time from operation of 34 months for simple adenomatous polyps and 21 months for those with advanced features. Patients with multiple polyps or advanced polyps at the initial colonoscopy were more likely to form subsequent polyps. Only 5.8% of patients with a single adenoma or a normal colon formed an advanced adenoma over the next 36 months of surveillance.Conclusion  The results of an empirical colonoscopic follow‐up programme compared favourably to the results of the intensive programmes reported in the literature. Most patients are at very low risk of developing significant colonic pathology over the first five years after resection. Colonoscopic surveillance intervals need not be less than five years unless the patient has multiple adenomas or advanced adenomas at the first colonoscopy. Three yearly surveillance intervals are most probably adequate in these individuals.
Rectal endosonography can distinguish benign rectal lesions from invasive early rectal cancers
Authors: Starck M. , Bohe M. , Simanaitis M. , Valentin L. 
Published: May 2003

AbstractObjective To determine whether an experienced ultrasound examiner, using good ultrasound equipment with high multifrequency probes, can discriminate between a high grade or low grade dysplastic adenoma (pT0) and very early invasive rectal cancers (pT1).Subjects and methods Sixty consecutive patients with clinically possibly pT0 or pT1 rectal tumours referred for transanal local excision underwent endorectal ultrasound examination. Lesions where the endorectal ultrasound image showed the mucosal layer to be expanded but the submucosal layer to be intact (uT0) were considered to represent a low grade or high grade dysplasia adenoma (pT0). An irregularity or disruption of the submucosal layer (uT1) was considered to characterize early invasive rectal cancers (pT1). The ultrasound staging was compared with the histological staging made on the basis of the diagnoses in the excised specimens.Results The histopathological diagnoses were: invasive rectal cancer (n = 18, 10 pT1, 4 pT2, 4 pT3 cancers); high grade dysplastic adenoma (n = 21); low grade dysplastic adenoma (n = 18); non adenomatous benign lesions (n = 3). Endorectal ultrasound incorrectly classified two of the invasive cancers (both pT1 tumours) as noninvasive lesions. Five of 42 pT0 tumours were overstaged as uT1 tumours. Overstaging was more common in patients who had undergone a previous excision and in tumours with peritumoral inflammation and desmoplastic reaction. The sensitivity of endorectal ultrasound with regard to invasive cancer was 89% (16/18), specificity 88% (37/42), positive predictive value 76% (16/21), negative predictive value 95% (37/39), and accuracy 88% (53/60). Among pT0 and pT1 tumours, the corresponding figures were 80% (8/10), 88% (37/42), 62% (8/13), 95% (37/39), and 87% (45/52).Conclusion Endorectal ultrasound can distinguish between noninvasive lesions and invasive rectal cancers clinically of stage pT0 or pT1.
Caecal‐diverticulitis: A rare differential diagnosis for right‐sided lower abdominal pain
Authors: Junge K. , Marx A. , Peiper Ch. , Klosterhalfen B. , Schumpelick V. 
Published: May 2003

AbstractObjective There are several differential diagnoses for acute abdominal discomfort with pain referred to the right lower quadrant region. The objective of this report is to outline our experience with diverticulitis of the caecum, which is a rare condition that is particularly difficult to diagnose correctly pre‐operatively.Methods A retrospective analysis of acute diverticulitis of the caecum was performed over the period from January 1992 to December 2000 within the Surgical Department of the RWTH Aachen, Germany. The progress of each patient was assessed by interviewing the patient and by telephone contact with the patient's general practitioner.Results Seven patients with isolated infective diverticulitis of the caecum were encountered in the course of this study. In five of these cases, the pre‐operative diagnosis was either unclear or incorrect. Four patients underwent surgery for suspected appendicitis. In one patient, the diverticulitis was diagnosed during laparoscopic surgery undertaken for presumed adnexal disease. Intestinal continuity was restored in all cases. The postoperative course was uneventful.Conclusions Right‐sided caecal diverticulitis is rare in comparison to diverticulitis of the sigmoid or descending colon. Nevertheless, it should be actively considered in the differential diagnosis of patients with acute tenderness in the right lower abdominal region.
Safety of primary anastomosis in emergency colo‐rectal surgery
Authors: Zorcolo L. , Covotta L. , Carlomagno N. , Bartolo D. C. C. 
Published: May 2003

AbstractBackground  The surgical management of left‐sided large bowel emergency patients remains controversial. There has been an increasing trend towards primary reconstructive surgery. The main dilemma remains appropriate patient selection for primary anastomosis.Methods  The records of 323 patients who presented as acute emergencies and underwent surgery between January 1990 and December 2000 for left‐sided colorectal cancer and diverticular disease were reviewed, to compare the outcome of resection and primary anastomosis with Hartmann's procedure. Patients were stratified into 3 groups according to whether the presentation was with localized or generalized peritonitis, or with obstruction.Results  Resection and anastomosis was carried out in 176 (55.7%) patients with a 30‐day mortality of 5.7%. Anastomotic dehiscence occurred in 9 (5.1%) patients, with no difference between the three groups. Wound sepsis occurred in 8 (4.5%) patients, and the median hospital stay was 13 days.Hartmann's resection was associated with a higher incidence of systemic and surgical morbidity (39.5% and 24.3%, respectively).The mortality rates in those selected for primary anastomosis (5.7%) compared favourably with those undergoing Hartmann's resections (20.4%) (P < 0.001).Conclusion  Emergency primary anastomosis in left‐sided disease can be performed with a low morbidity and mortality in selected patients, even in the presence of a free perforation with diffuse peritonitis. Patients selected for staged resection, were those with major comorbid disease.
The rhomboid flap for pilonidal disease
Authors: Arumugam P. J. , Chandrasekaran T. V. , Morgan A. R. , Beynon J. , Carr N. D. 
Published: May 2003

AbstractIntroduction  There have been many surgical techniques described for the treatment of pilonidal sinuses. Recurrent disease causes significant morbidity particularly with time from work.Aim  To assess the rhomboid flap's role in promoting one‐stage primary healing in pilonidal disease and to evaluate the morbidity and recurrence.Methods  Fifty‐three patients were prospectively recruited of which 27 had previous multiple abscess formation requiring surgical drainage from their pilonidal disease, although none had acute disease at the time of surgery. By using the transposition flap, we were able to obliterate the natal cleft and therefore the rolling action of the buttocks between the cleft in these patients and thereby remove one of the factors involved in pilonidal disease. Hospital stay, healing time, wound infection, wound breakdown and recurrence were noted.Results  There were 47 males and 6 females with a median age of 28 years (range 16–64 years). Median follow‐up was 24 months (range 3–36 months). Post‐operative morbidity involved superficial wound infection in 7 (13%) which settled with out‐patient dressings. There were four recurrences (7%), two occurred between the flap and the anal canal, and the other two in the flap margin needing intervention. All the patients healed their wounds and the median healing time was 14 days.Conclusion  As this condition affects a predominantly young population causing significant time off from work, we feel that the Rhomboid Flap is useful for difficult cases in that it allows early return to full activity and does not necessitate prolonged postoperative care.