bluuebunny/crossref_metadata_2025 huggingface dataset:
Community reassembly: a test using limestone grassland in New Zealand
Authors: Lord  , Wilson  , Steel  , Anderson
Published: March 2003

To examine community reassembly, we sampled grasslands on calcareous soil (4%–24% CaCO3) in New Zealand that were largely composed of species introduced from Britain. We tested whether the British species had reassembled on New Zealand limestone into the same communities as they form on limestone in Britain. The vegetation of six New Zealand sites was sampled, each with ten 2 × 2 m quadrats that followed the standard methodology of the British National Vegetation Classification (NVC). Analysing species presence and cover using program TableFit with the full database of British species, the New Zealand species assemblages gave poor to moderate fits (40%–72%) to the communities of the NVC, and even then not to calcareous grassland, though one site did fit to a calcareous spring community. The poor fits can be partly attributed to the absence from New Zealand of many British calcareous‐specialist species. On omitting from the NVC database all species not present in New Zealand, the fits increased somewhat to 48%–77%. Using this modified database, two sites fitted British calcareous grassland communities. These two sites are on thinner soil (<10 cm depth), under lower rainfall. Where fits were obtained to calcareous communities, the environment of the community in Britain matched very well that of the New Zealand site. It is concluded that environmental and perhaps biotic filtering has been strong enough in some sites to assort alien species into the same species assemblages as they form in their native range, indicating the Deterministic model of community structure. However, the absence of some species has prevented full reassembly.
On detecting and measuring competition in spatially structured plant communities
Authors: Freckleton R.P. , Watkinson A.R.
Published: March 2003

Recent models have shown that the development of spatial structure in plant mixtures may make strong competitive interactions between species hard to detect owing to spatial segregation of the competing species. Here we address the issue of measuring interspecific competition using a simulation based on a neighbourhood population model which assumes that both dispersal and competitive interactions are localized. Using known parameter combinations we use the model to test the power and efficiency of two approaches for detecting and measuring competition. The first approach is based on measuring the response of communities to the removal of neighbours. Measures of interspecific competition based on this approach are extremely biased by spatial segregation of species, although this bias may be partially overcome by altering the spatial scale at which the effects of removals are recorded. The second approach is based on multiple regression of per capita population growth rates on local densities of the interacting species. When dispersal is restricted, the regression approach provides accurate estimates of interspecific competition coefficients when the scale of the sampling unit (i.e. the quadrats within which plants are counted) is large compared to the scale at which interactions and dispersal occur. When seeds disperse globally the removal method performs best; the regression method fails because sampling units do not form closed dynamic systems. Our results highlight the importance of tailoring methods for detecting competition to the characteristics of the species in question. They also indicate that rapid nonmanipulative estimates of competition coefficients may be the best approach in communities where dispersal is restricted and competitive interactions localized, which is likely to be the case for the majority of plants.
Parasites reduce territorial behaviour in red grouse (Lagopus lagopus scoticus)
Authors: Fox  , Hudson
Published: March 2003

Hypotheses for the cause of population cycles have focused on the role of intrinsic mechanisms such as spacing behaviour and extrinsic mechanisms such as parasitism and predation. This paper examines the interaction between the two dominant hypotheses in the cycles of red grouse, parasitism and spacing behaviour. The influence of the caecal nematode, Trichostrongylus tenuis, on male aggressiveness was investigated using two approaches. First, the territorial behaviour of a group of male grouse experimentally treated with an anthelmintic to reduce parasite intensities was compared with a control group with natural intensities of infection. Second, the response of treated and control males to a novel conspecific territorial intruder were recorded using playback tests. Treated males, with reduced levels of parasitism, won significantly more territorial contests than control males and produced more aggressive behaviour in response to the playback recordings. These results show that parasite removal enhanced aggressive behaviour. Implications of these results on red grouse population dynamics are discussed.
Coevolution of parasite virulence and host life history
Authors: Koella Jacob C. , Restif Olivier
Published: March 2003

Most models about the evolutionary interactions between a parasite’s virulence and its host’s life history neglect two potentially important aspects: epidemiological and coevolutionary feedback. We emphasize their importance by presenting models that describe the coevolution of a semelparous host’s age at reproduction and a parasite’s virulence in different environmental conditions. In particular, we first show that an epidemiological feedback will lead to a nonmonotonic response of the host’s age at reproduction as virulence increases. We then show that the coevolutionary pressure on virulence can lead to complex associations between the host’s life history and the parasite’s virulence, which would not be expected with more traditional models of host or parasite evolution. Thus, for example, a high mortality rate of the host favours avirulent parasites and late reproduction of the host when the environmental conditions allow the host to grow rapidly, but early reproduction and high virulence when growth is slow.
Local adaptation enhances performance of common plant species
Authors: Joshi J. , Schmid B. , Caldeira M. C. , Dimitrakopoulos P. G. , Good J. , Harris R. , Hector A. , Huss‐Danell K. , Jumpponen A. , Minns A. , Mulder C. P. H. , Pereira J. S. , Prinz A. , Scherer‐Lorenzen M. , Siamantziouras A.‐S. D. , Terry A. C. , Troumbis A. Y. , Lawton J. H.
Published: March 2003

Geographic variation can lead to the evolution of different local varieties, even in widespread forage plants. We investigated the performance of common forage plants in relation to their genetic diversity and local adaptation at a continental scale using reciprocal transplants at eight field sites across Europe over a 2‐year period. The overall performance of the three test species,Trifolium pratense,Dactylis glomerata,Plantago lanceolata, was generally highest for plants replanted at their home site and declined with increasing transplanting distance. The three species differed in the fitness components responsible for the increased overall performance and selection advantage at home sites. In addition to the effects of local adaptation, the majority of measured traits in all three species also showed ecotypic variation. However, no single ecotype of any species was able to outperform the locally adapted strains and do best at all sites, highlighting the importance of maintaining these plant genetic resources.
Small‐scale spatial patterns determine ecological relationships: an experimental example using nectar production rates
Authors: Klinkhamer Peter G. L. , De Jong Tom J. , Linnebank Lucas A.
Published: March 2003

The structuring of populations at small scales has important consequences for ecological relationships and may contribute to the maintenance of genetic diversity within populations. As an example we tested the effects of variation in nectar production rates (NPR) on pollinator visitation in experimental populations of Echium vulgare with different spatial arrangements. Bumblebees discriminate between groups of plants with different NPRs only when these groups are separated by distances larger than 6 m. Within groups, plants with high and low NPR receive similar numbers of approaches. Plants with high NPR increase the average number of approaches to all plants in the group; therefore, plants with low NPR benefit from nectar‐rich plants nearby. These results demonstrate that the effects of NPR on pollinator service depend on the spatial structuring of the population. We suggest that this may help to explain the large genetic differences in NPR that we find for E. vulgare at our study site.
Extinction times for closed epidemics: the effects of host spatial structure
Authors: Park Andrew W. , Gubbins Simon , Gilligan Christopher A.
Published: March 2003

Although of practical importance, the relationship between the duration of an epidemic and host spatial structure is poorly understood. Here we use a stochastic metapopulation model for the transmission of infection in a spatially structured host population. There are three qualitatively different regimes for the extinction time, which depend on patch population size, the within‐patch basic reproductive number and the strength of coupling between patches. In the first regime, the extinction time for the metapopulation (i.e. from all patches) is approximately equal to the extinction time for a single patch. In the second regime, the metapopulation extinction time is maximal but also highly variable. In the third regime, the extinction time for the metapopulation (TE) is given byTE = a + bn1/2whereais the local extinction time (i.e. from last patch),bis the transit time (i.e. the time taken for infection to spread from one patch to another) andnis the total number of patches.
Interaction between bacteriophage PBS1 and clay minerals and transduction of Bacillus subtilis by clay–phage complexes
Authors: Vettori  , Stotzky  , Yoder  , Gallori
Published: March 2003

Bacteriophage PBS1 of Bacillus subtilis was rapidly adsorbed on montmorillonite (M) and kaolinite (K), and adsorption was maximal after 30 min on both clays. There was no correlation between adsorption and the cation exchange capacity of the clays. Studies with sodium metaphosphate (a polyanion that interacts with positively charged sites on clay) indicated that positively charged sites on K were primarily responsible for the adsorption of the phage, whereas other mechanisms appeared to be involved in adsorption of the phage on M. X‐ray diffraction and electron microscopic analyses showed that the phage partially intercalated M. Survival of the phage was increased by adsorption on the clays, and adsorbed phage maintained its ability to transduce bacterial cells for at least 30 days (the longest time studied) after the preparation of the clay–phage complexes. Electron microscopic observations indicated that transduction by the clay–phage complexes was primarily the result of the phage detaching from the clays in the presence of host cells.
Antigen 43 facilitates formation of multispecies biofilms
Authors: Kjærgaard Kristian , Schembri Mark A. , Ramos Cayo , Molin Søren , Klemm Per
Published: March 2003

Antigen 43 (Ag43) is a surface‐displayed autotransporter protein of Escherichia coli. By virtue of its self‐association characteristics, this protein is able to mediate autoaggregation of E. coli cells in static cultures. Here, we show that Ag43 can be expressed in a functional form on the surface of Pseudomonas fluorescens. Ag43 expression dramatically enhances the biofilm‐forming potential of both E. coli and P. fluorescens to abiotic surfaces in simple microtitre well assays and in flow chambers. Importantly, Ag43‐expressing E. coli and P. fluorescens cells tagged with Gfp and Rfp were shown to form interwoven biofilms in flow chambers. The three‐dimensional structures of the biofilms were analysed by laser‐confocal microscopy. Heterogeneous expression of Ag43 induced interspecies cell‐to‐cell contact that generated multispecies biofilm formation. Our data indicate that this versatile molecular tool can be used for the rational design of multispecies biofilms. More specifically, this novel technology offers opportunities for the design of multispecies consortia in which the concerted action of several bacterial species is required, e.g. waste treatment and degradation of pollutants.
Bacterial populations occurring in a trichloroethylene‐contaminated aquifer during methane injection
Authors: Baker Paul , Futamata Hiroyuki , Harayama Shigeaki , Watanabe Kazuya
Published: March 2003

Soil core samples were obtained from a trichloroethylene (TCE)‐contaminated aquifer before and after the start of methane biostimulation. DNA was extracted directly from the soil samples, and denaturing gradient gel electrophoresis (DGGE) was used to analyse bacterial 16S ribosomal DNA fragments that were PCR amplified from these DNA samples. This analysis consistently detected two phylotypes in the methane‐injected samples. These phylotypes were closely related to Methylobacter and Methylomonas, both belonging to type I methanotrophs. A competitive DGGE analysis using Methylosinus trichosporium OB3b cells as an internal quantitative standard showed that these populations accounted for 108−109 cells g−1 soil. These results showed that type I methanotrophs formed a significant proportion of the bacterial community during methane biostimulation. The implications of this finding for TCE bioremediation were discussed.
Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil
Authors: Zézé Adolphe , Mutch Lesley A. , Young J. Peter W.
Published: March 2003

Sequences of nodD, a gene found only in rhizobia, were amplified from total community DNA isolated from a pasture soil. The polymerase chain reaction (PCR) primers used, Y5 and Y6, match nodD from Rhizobium leguminosarum biovar trifolii, R. leguminosarum biovar viciae and Sinorhizobium meliloti. The PCR product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii[11 restriction fragment length polymorphism (RFLP) types] and 15 clones identified as viciae (seven RFLP types). These identifications were confirmed by sequencing. There were no clones related to S. meliloti nodD. For comparison, 122 strains were isolated from nodules of white clover (Trifolium repens) growing at the field site, and 134 from nodules on trap plants of T. repens inoculated with the soil. The nodule isolates were of four nodD RFLP types, with 77% being of a single type. All four of these patterns were also found among the clones from soil DNA, and the same type was the most abundant, although it made up only 34% of the trifolii‐like clones. We conclude that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant than biovar viciae in this pasture soil, whereas S. meliloti was rare.
Bioavailability of solid and non‐aqueous phase liquid (NAPL)‐dissolved phenanthrene to the biosurfactant‐producing bacterium Pseudomonas aeruginosa 19SJ
Authors: García‐Junco Marta , De Olmedo Elvira , Ortega‐Calvo José‐Julio
Published: March 2003

The biodegradation of phenanthrene by the biosurfactant‐producing strain Pseudomonas aeruginosa 19SJ was investigated in experiments with the compound present either as crystals or dissolved in non‐aqueous phase liquids (NAPLs). Growth on solid phenanthrene exhibited an initial phase not limited by dissolution rate and a subsequent, carbon‐limited phase caused by exhaustion of the carbon source. Rhamnolipid biosurfactants were produced from solid phenanthrene and appeared in solution and particulate material (cells and phenanthrene crystals). During the carbon‐limited phase, the concentration of rhamnolipids detected in culture exceeded the critical micelle concentration (CMC) determined with purified rhamnolipids. The biosurfactants caused a significant increase in dissolution rate and pseudosolubility of phenanthrene, but only at concentrations above the CMC. Externally added rhamnolipids at a concentration higher than the CMC increased the biodegradation rate of solid phenanthrene. Mineralization curves of low concentrations of phenanthrene initially dissolved in two NAPLs [2,2,4,4,6,8,8‐heptamethylnonane and di(2‐ethylhexyl)phthalate] were S‐shaped, although no growth was observed in the population of suspended bacteria. Biosurfactants were not detected in solution under these conditions. The observed mineralization was attributed not only to suspended bacteria, but also to bacterial populations growing at the NAPL–water interface, mineralizing the compound at higher rates than predicted by abiotic partitioning. We suggest that rhamnolipid production and attachment increased the bioavailability of phenanthrene, so promoting biodegradation activity.
Strain characterization and 16S‐23S probe development for differentiating geographically dispersed isolates of the phytopathogen Ralstonia solanacearum
Authors: Timms‐Wilson Tracey M. , Bryant Kirsty , Bailey Mark J.
Published: March 2003

The causative agent of potato brown rot and bacterial wilt, Ralstonia solanacearum, results in serious world‐wide economic losses, particularly in the tropics. In the last decade, however, the incidence of bacterial wilt in potatoes grown in Northern Europe has increased, presenting an interesting epidemiological puzzle. Its occurrence may be as a result of changes in agricultural practice or the emergence of a novel bacterial variety, better adapted to cooler conditions. To understand the distribution and genetic diversity of this phytopathogen, we have analysed a collection of 82 isolates from Europe and tropical regions. Both phenotypic [SDS–PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis) profiling, FAME (fatty acid methyl esters) analysis, growth profiles and EPS (exopolysaccharide) production] and genotypic [16S rRNA RFLP (restriction fragment length polymorphism), ARDRA (amplified ribosomal DNA restriction analysis) and sequence analysis of 16S−23S rRNA ITS and flanking regions] methods were compared. Principal component analysis of FAME profiles clustered isolates into three groups and ARDRA of a 0.85 kb amplified fragment from the 16S‐23S ITS region differentiated isolates into four groups. Using sequence analysis, specific primers were designed within the variable region 147–170 of the 23S rRNA. These primers, RsolT2 and RsolT3, respectively, differentiated isolates into two distinct clusters as described previously by Wullings and colleagues (Wullings et al., 1998). The European strains (Biovar 2, race 3) analysed in this study specifically hybridized with RsolT3, and showed considerable genetic homogeneity when compared with strains of other races from ‘the rest of the world’. These data indicate the possible selection and proliferation of a ‘European’‐adapted variant.
Osmoadaptation in bacteria and archaea: common principles and differences
Authors: Roeßler Markus , Müller Volker
Published: March 2003

The availability of water is the most important prerequisite for life of any living cell, and exposure of cells to hypersaline conditions always threatens the cells with a drastic loss of water. To re‐establish the essential turgor pressure, cells increase the water activity of their cytoplasm by accumulation of compatible solutes, either by synthesis or by uptake. The ability to respond to increasing osmolality is well conserved in all three lines of descent and, here, we compare the osmoadaptive strategies of Bacteria and Archaea. The temporal sequence of events after an osmotic upshock will be discussed, with a focus on the most rapid response, notably the mechanisms of transport activation at the protein level, and different signals for osmolality will be compared. The spectrum of compatible solutes used by different organisms is rather diverse and a comparison of ‘bacterial’ and ‘archaeal’ compatible solutes will be given.
Changes in archaeal, bacterial and eukaryal assemblages along a salinity gradient by comparison of genetic fingerprinting methods in a multipond solar saltern
Authors: Casamayor Emilio O. , Massana Ramon , Benlloch Susana , Øvreås Lise , Díez Beatriz , Goddard Victoria J. , Gasol Josep M. , Joint Ian , Rodríguez‐Valera Francisco , Pedrós‐Alió Carlos
Published: March 2003

Microbial communities inhabiting a multipond solar saltern were analysed and compared using SSU rRNA polymerase chain reaction (PCR)‐based fingerprintings carried out in parallel by four laboratories. A salinity gradient from seawater (3.7%) to NaCl precipitation (37%) was studied for Bacteria, Archaea and Eukarya, and laboratories applied their own techniques and protocols on the same set of samples. Members of all three domains were retrieved from all salt concentrations. Three fingerprinting techniques were used: denaturing gradient gel electrophoresis (DGGE), ribosomal internal spacer analysis (RISA), and terminal‐restriction fragments length polymorphism (T‐RFLP). In addition, each laboratory used its own biomass collection method and DNA extraction protocols. Prokaryotes were addressed using DGGE and RISA with different ‘domain‐specific’ primers sets. Eukaryotes were analysed by one laboratory using DGGE and T‐RFLP, but targeting the same 18S rDNA site. Fingerprints were compared through cluster analysis and non‐metric multidimensional scaling plots. This exercise allowed fast comparison of microbial assemblages and determined to what extent the picture provided by each laboratory was similar to those of others. Formation of two main, salinity‐based groups of samples in prokaryotes (4–15% and 22–37% salinity) was consistent for all the laboratories. When other clusters appeared, this was a result of the particular technique and the protocol used in each case, but more affected by the primers set used. Eukaryotic microorganisms changed more from pond to pond; 4–5% and 8–37% salinity were but the two main groups detected. Archaea showed the lowest number of bands whereas Eukarya showed the highest number of operational taxonomic units (OTUs) in the initial ponds. Artefacts appeared in the DGGE from ponds with extremely low microbial richness. On the other hand, different 16S rDNA fragments with the same restriction or internal transcribed spacer (ITS) length were the main limitations for T‐RFLP and RISA analyses, respectively, in ponds with the highest OTUs richness. However, although the particular taxonomic composition could vary among protocols, the general structure of the microbial assemblages was maintained.
Prokaryotic genetic diversity throughout the salinity gradient of a coastal solar saltern
Authors: Benlloch Susana , López‐López Arantxa , Casamayor Emilio O. , Øvreås Lise , Goddard Victoria , Daae Frida Lise , Smerdon Gary , Massana Ramón , Joint Ian , Thingstad Frede , Pedrós‐Alió Carlos , Rodríguez‐Valera Francisco
Published: March 2003

Bacterial and archaeal assemblages have been studied in a multipond solar saltern using a range of microbial ecology techniques by four laboratories simultaneously. These include 16S rDNA sequencing from both denaturing gradient gel electrophoresis (DGGE) and clone libraries, and culturing methods. Water samples from eight ponds were analysed, covering a salinity range from near sea water (4% salt) to saturated sodium chloride (37% salt; ponds called crystallizers). Clone libraries focused on ponds with salinity of 8%, 22% and 32%. Although different cloning strategies were able to retrieve the same type of dominant sequences, there were differing degrees of success with less abundant sequences. Thus, the use of two sets of primers recovered a higher number of phylotypes. Bacterial and archaeal isolates were, however, different from any of the retrieved environmental sequences. For Bacteria, most sequences in the 8% salt pond were related to organisms of marine origin. Thus, representatives of the alpha‐, beta‐, gamma‐ and epsilon‐subdivisions of Proteobacteria, the Cytophaga–Flavobacterium–Bacteroides
group (CFB), high‐G+C Gram‐positive bacteria and cyanobacteria were found. In the
22% salt pond, alpha‐ and gamma‐Proteobacteria, cyanobacteria and CFB were
the only groups found, and most of them were related to specialized halophilic bacteria.
From the 32% salt pond, only CFB were found, and most of the sequences retrieved
clustered with Salinibacter ruber, an extremely halophilic bacterium. A decrease
in the richness of bacterial genera was therefore apparent along the gradient. Archaea
behaved quite similarly. In the lowest salinity ponds, sequences were related to
environmental clones of Marine Archaea Group III (Thermoplasmales relatives)
and to unclassified branches of Euryarchaeaota. In the 8%, 22% and
32% ponds, most of the clones were related to different cultured strains
of Halobacteriaceae. Finally, most sequences from the crystallizers clustered with
the uncultured square archaeon SPhT. Crenarchaeaota were not detected. Despite the
fact that higher prokaryotic richness was apparent in the lower salinity ponds than
in the crystallizers, the diversity index from clone libraries calculated according
to Shannon and Weaver did not show this trend. This was because diversity in the
crystallizers can be considered as ‘microdiversity’, the co‐existence
of several closely related clones of Bacteria (the S. ruber cluster) and Archaea (the SPhT cluster). Regardless of the changes in abundance, both Bacteria and Archaea showed the same pattern; as salinity increased, the number of different clusters decreased, and only one cluster became dominant. Both clusters, however, showed a considerable degree of microdiversity. The meaning of such microdiversity remains to be determined.
Mitigation of avian reproductive tract function by Salmonella enteritidis producing high‐molecular‐mass lipopolysaccharide
Authors: Parker Craig T. , Harmon Barry , Guard‐Petter Jean
Published: March 2003

Hens were infected with a wild‐type Salmonella enteritidis and its wzz mutant, which lacked the ability to make high‐molecular‐mass lipopolysaccharide (LPS), in six experiments paired by dosage and route of exposure. Involution of the reproductive tract occurred in 86% of hens that were injected subcutaneously with 108 cfu of the wild‐type strain, but none did so when injected with the wzz mutant. In spite of the lack of a specific effect on the reproductive tract, infection of hens with the mutant produced more contaminated eggs and heterophilic granulomas in developing ova (yolks) than wild type; thus, overall, the mutant appeared to be more virulent except after intravenous injection. The mutant also decreased shell quality more often than wild type, regardless of dosage or route of infection. These results suggest that egg‐contaminating Salmonella enteritidis that produces high‐molecular‐mass LPS mitigates signs of illness in poultry by altering the response of the avian reproductive tract to infection, but without altering the incidence of egg contamination following bacteraemia. Further research is warranted to determine whether analyses of shell quality might aid in identification of flocks at risk of producing contaminated eggs.
Evolution of a chlorobenzene degradative pathway among bacteria in a contaminated groundwater mediated by a genomic island in Ralstonia
Authors: Müller Tina Andrea , Werlen Christoph , Spain Jim , Van Der Meer Jan Roelof
Published: March 2003

The genetic structure of two Ralstonia spp., strain JS705 and strain JS745, isolated from the same groundwater aquifer, was characterized with respect to the degradation capacities for toluene and chlorobenzene degradation. Cosmid library construction, cloning, DNA sequencing and mating experiments indicated that the genes for chlorobenzene degradation in strain JS705 were a mosaic of the clc genes, previously described for Pseudomonas sp. strain B13, and a 5 kb fragment identical to strain JS745. The 5 kb fragment identical to both JS705 and JS745 was flanked in JS705 by one complete and one incomplete insertion (IS) element. This suggested involvement of the IS element in mobilizing the genes from JS745 to JS705, although insertional activity of the IS element in its present configuration could not be demonstrated. The complete genetic structure for chlorobenzene degradation in strain JS705 resided on a genomic island very similar to the clc element (Ravatn, R., Studer, S., Springael, D., Zehnder, A.J., van der Meer, J.R. 1998. Chromosomal integration, tandem amplification, and deamplification in Pseudomonas putida F1 of a 105‐kilobase genetic element containing the chlorocatechol degradative genes from Pseudomonas sp. strain B13. J Bacteriol 180: 4360–4369). The unique reconstruction of formation of a metabolic pathway through the activity of IS elements and a genomic island in the chlorobenzene‐degrading strain JS705 demonstrated how pathway evolution can occur under natural conditions in a few ‘steps’.
Sialosyl‐Tn expression in benign and neoplastic proliferative lesions of the colon: of questionable value in predicting dysplasia
Authors: Fogt  , Zimmerman  , Furth  , Deren  , Noffsinger  , Poremba  , Alsaigh
Published: March 2003

Objectives

Tumour‐associated carbohydrate antigen expression patterns have been observed to change during the transformation from benign to dysplastic and malignant cells. Sialosyl‐Tn is an O‐linked mucin‐type tumour‐associated antigen expressed on glycoproteins and is the product of aberrant glycosylation of the Tn glycoprotein, an early precursor of the MN blood group antigen. Sialosyl‐Tn expression has been observed in adenomas and carcinomas of the colon as well as in dysplastic lesions in ulcerative colitis (UC). Sialosyl‐Tn expression has been proposed to be a prognostic marker for the development of dysplasia in UC.

Patients and methods

To evaluate Sialosyl‐Tn expression in benign and malignant proliferative lesions of the colon, and its relevance for prediction of dysplasia, we immunostained cases of adenoma, adenoma with invasive carcinoma, UC with and without dysplasia, hyperplastic polyps, cases of lymphocytic colitis, and cases of acute self‐limited colitis with antibody against Sialosyl‐Tn.

Results

We found expression of Sialosyl‐Tn in dysplastic lesions in adenomas and UC. We also found expression of Sialosyl‐Tn in epithelium of chronic colitis in virtually all patients with UC, both with dysplasia and without. Sialosyl‐Tn was also present in hyperplastic polyps, and one single case each of lymphocytic colitis and acute self‐limited colitis.

Conclusion

We conclude that Sialosyl‐Tn is expressed in dysplastic and malignant epithelial lesions of the colon. Expression of Sialosyl‐Tn in benign proliferative/regenerative lesions in the colon is frequent and is not directly related to the development of dysplasia. Possible mechanisms of Sialosyl‐Tn expression are discussed.
Linear stapled haemorrhoidectomy—an alternative to standard haemorrhoidectomy?
Authors: Abbasakoor  , Nelson  , Patel  , Morgan  , Carr  , Woodward  , Beynon
Published: March 2003

Objective

To evaluate in a pilot study a new haemorrhoidectomy technique involving the use of a linear stapling device.

Patients and methods

Twenty consecutive unselected patients (12 male, eight female; median age 64 years, range 40–81 years) underwent haemorrhoidectomy using the new technique. Fifteen also underwent pre‐ and post‐operative endoanal ultrasound to assess the anal sphincter complex.

Results

The operation was successfully carried out on all patients. Analgesic requirements were low, with most patients requiring no analgesia or paracetamol only. The majority of patients (n=13) were discharged on the first post‐operative day. Clinically all patients remained fully continent of flatus and faeces after surgery with no recurrence of haemorrhoids. There was no morphologic evidence of internal or external anal sphincter damage in the patients who underwent endoanal ultrasound. There were no re‐admissions of patients immediately after discharge. One late complication involving persistent anal discomfort from retained staples necessitated an operation to have them removed.

Conclusion

This study suggests that the use of a linear stapling device for haemorrhoidectomy is safe, being associated with little post‐operative pain, a low complication rate and early discharge. A prospective randomized trial is required to assess this new treatment.
Results of a selective policy for preoperative radiotherapy in rectal cancer surgery
Authors: Gandy  , O’Leary  , Falk  , Roe
Published: March 2003

Objective

Preoperative radiotherapy (pRT) for rectal cancer may reduce local recurrence and improve survival. This study was undertaken to assess a selective policy of pRT in rectal cancer. The aim was to determine whether patients likely to have involved circumferential margins (CRM) could be reliably selected for pRT using clinical criteria. We have used CRM and delay in surgery as outcome measures.

Patients and methods

Seventy‐nine patients with rectal cancer were assessed for preoperative radiotherapy using clinical criteria.

Results

Twelve of 26 (46%) pRT patients had positive CRM compared with three of 53 (5.6%) who did not receive pRT (P < 0.0001). Using pRT resulted in patients waiting a further 21 days before surgery (pRT 34 days vs no pRT 13 days; P < 0.0001).

Conclusion

This policy has been effective in selecting patients most likely to benefit from radiotherapy and has avoided excessive delays prior to surgery. However, almost half of the pRT patients did not have involved CRM. With improved imaging techniques we may be able to refine our selection criteria further.
The cost effectiveness of self‐expanding metal stents in the management of malignant left‐sided large bowel obstruction
Authors: Osman  , Rashid  , Sathananthan  , Parker
Published: March 2003

Objective

Self‐expanding metal stents have been developed to treat acute left‐sided large bowel obstruction, either for palliation or for bowel decompression prior to subsequent abdominal surgery. The cost effectiveness of stenting vs surgical decompression has been analysed.

Patients and methods

Between April 1997 and April 1998, 16 patients with acute large bowel obstruction were managed by self‐expanding metal stents. This group was compared with 10 unselected patients previously managed by surgical decompression. The cost‐effectiveness of stenting was compared with surgical decompression by analysis of total hospital stay, running costs, and operating theatre/radiology suite utility. This was extended to include stented patients who proceeded to elective anterior resection (n=5) and patients managed by Hartmann’s operation who proceeded to reversal (n=6).

Results

The results showed significant reduction in the total hospital stay in the stent group, with a mean hospital stay of 2.5 days compared with 13.5 days in the surgical decompression group. There was also a mean net saving of £1760 per stented patient, with a cumulative annual saving of £26 400 on an average of 15 cases stented per year. In patients who proceeded either to post‐stenting anterior resection, or reversal of Hartmann’s operation, the mean hospital stay was 17 days and 23.5 days (including hospital stay for decompression procedure), respectively, with a mean net saving of £685 per stented patient.

Conclusion

Stenting of acute large bowel obstruction is a cost‐effective procedure with a reduction in total hospital stay and expenditure compared with surgical decompression.
Telomerase inhibition as a potential new therapy for colorectal cancer
Authors: Ghori  , Usselmann  , Odogwu  , Fraser  , Morris
Published: March 2003

Colorectal cancer represents the second leading cause of cancer‐related deaths. Despite local tumour control, patients die from disseminated disease and improved therapy is clearly required. One possible new approach is inhibition of telomerase, a reverse‐transcribing enzyme thought to be essential to prevent senescence of cells by synthesizing chromosomal telomeres, which is reactivated in 85–95% of colorectal cancers. The purpose of this study was to determine the degree of telomerase inhibition by known retroviral reverse‐transcriptase inhibitors using concentrations that are not acutely toxic to cells. The concentrations of three drugs (azidothymidine (AZT); dideoxythymidine (ddT); and dideoxyguanidine (ddG)) needed to reduce the proliferation (ID50) of the colorectal cell line HT29 by 50% were determined. Extracts were made of cells exposed for 24–48 h to these concentrations of each prodrug, telomerase activity determined using the Telomerase Repeat Amplification Protocol (TRAP), quantifying polymerase chain reaction products generated by telomerase with a phosphorimager and ImageQuantTM software. The drug treatments reduced the activity of telomerase in these cells by 97% for AZT, 38% for ddT and 47% for ddG, compared with control extracts. In order to confirm that the drugs used were directly inhibitory to telomerase, extracts of control cells were exposed to the active (phosphorylated) drugs and telomerase activity determined: greater than 60% and 80% inhibition occurred at 0.02 m
M and 0.04 m
M concentration of ddT and ddG, respectively. (The phosphorylated form of AZT was not available.) Control experiments demonstrated that the action of the active drug was not at the PCR stage of the TRAP assay and so was directly exerted on telomerase. We conclude that reverse transcriptase inhibitors can directly inhibit telomerase in cells exposed to prodrug concentrations, which are not acutely toxic, and that the active drug does directly inhibit telomerase. We propose that such inhibitors may have a role in reducing the survival, by inducing senescence, of remaining malignant cells after potential curative surgery, thus reducing recurrence and improving the prognosis of the disease. In addition they may be used in high‐risk susceptible patients and in early‐stage cancers.
Rectovaginal fistulae in Crohn’s disease: a management paradox
Authors: Windsor  , Lunniss  , Khan  , Rumbles  , Williams  , Northover
Published: March 2003

Objective

Much has been written about the management of rectovaginal fistulae in Crohn’s disease (CD), but there remains little or no consensus on the optimal therapeutic approach. This retrospective case review examined treatment and clinical outcome of women presenting with rectovaginal fistula between 1985 and 1995 in an attempt to clarify treatment guidelines.

Patients and methods

A total of 48 case notes was reviewed. Significant symptoms and signs were noted at presentation in 73% and 65% of women, respectively, and fistula classification revealed; three (6%) superficial, 36 (76%) transphincteric, six (12%) suprasphincteric and three (6%) unclassified.

Results

Fifteen patients were initially treated conservatively, of whom 73% were eventually rendered asymptomatic and none required proctectomy. Of the remaining 33 fistulae, 12 were treated by laying open or seton insertion, 13 by local repair using transperineal proctotomy or advancement flaps, two by defunctioning alone, and six by proctectomy. Eighty‐three percent of patients undergoing laying open or seton insertion, 77% following local repair and 50% following stoma were eventually rendered asymptomatic. The proctectomy rates were 42%, 15%, and 50% in these three groups, respectively.

Conclusion

The results of this study suggest that in the absence of significant symptoms, conservative management provides a good chance of fistula healing without need for proctectomy. However, if symptoms dictate the need for intervention, local repair provides a similar chance of success with a lower ultimate need for proctectomy than laying open or seton. Despite these broad generalities, this study highlights the difficulties we have in advising patients with proctovaginal fistulae in CD.
Evaluation of colonoscopic sized biopsies for microsatellite instability and adenomatous polyposis coli (APC) variants
Authors: Sengupta  , Pearson  , Yiu  , Boulos
Published: March 2003

Objective

Knowledge of certain genetic changes associated with the development of colorectal cancer may influence surgical treatment in the future. Cancers are known to show intratumoural genetic heterogeneity. The aim of this study was to determine whether colonoscopic sized biopsies provide enough tissue to overcome the effects of tumour heterogeneity for the results of genetic analysis to be representative of the tumour as a whole.

Patients and methods

Using colonoscopic biopsy forceps, samples were taken from 30 resected colorectal cancers and investigated for microsatellite instability (MSI) at five loci and changes in the adenomatous polyposis coli gene (APC) by single‐stranded conformational polymorphism analysis. Identical genetic analysis was carried out on larger specimens taken from each of these cancers to determine whether the molecular findings from the large specimen were the same as those from colonoscopic sized biopsies.

Results

The microsatellite instability and APC status of the colonoscopic sized biopsies and those from larger specimens were completely consistent.

Conclusion

These results suggest that colonoscopic sized biopsies are reliable in determining the MSI status and APC variants of individual colorectal cancers.
Improved results in rectal cancer surgery—an effect of specialization?
Authors: Machado  , Goldman  , Järhult
Published: March 2003

Objective

The surgeon‐ and hospital‐related variability in outcome after surgery for rectal cancer has been much debated. This study comprises a 6‐year period of rectal cancer treatment at a single surgical Institution, where substantial changes in the treatment strategy of rectal cancer were implemented.

Patients and methods

Prospective and retrospective analysis of complications, stoma frequency, local recurrence rate and survival in 252 patients operated on for rectal cancer before (1990–1992) and after (1994–1996) the creation of a specialized rectal cancer team.

Results

Specialization led to a significant decrease both in the need of permanent stomas (52% before vs 33% after specialization; P=0.02) and in the frequency of local recurrence (18% vs 3%; P=0.002). No increase in the frequency of post‐operative complications, re‐operations or, specifically, pelvic sepsis could be detected in the later period, although more extensive surgery was used and the anastomotic level decreased from 8 to 4 cm (P < 0.001). Cancer‐specific survival at 2 years after operation was significantly higher in patients operated in 1994–1996 than in those operated 1990–1992 (P=0.006).

Conclusion

Concentrating the care of patients with rectal cancer to a specialized team seems to improve quality and outcome.
Utility of appropriate peritonitis grading in the surgical management of perforated sigmoid diverticulitis
Authors: Thaler K. , Neumann F. , Gerö A. , Kreuzer W.
Published: March 2003

Objective

We evaluated the prognostic validity of preoperative risk scores in the surgical management of patients with diverticular perforation and diffuse peritonitis.

Patients and methods

From 1988 to 1998, 82 patients, mean age 72 ± 15 years, underwent urgent surgery for perforated diverticulitis with generalized peritonitis. They were operated either with the Hartmann technique or with resection and primary anastomosis. ASA Classification and Mannheimer Peritonitis Index (MPI) were documented as risk scores at time of surgery and used as guidelines to decide for one of both procedures.

Results

A Hartmann resection (HA) was performed in 62 patients (76%) and resection with primary anastomosis (PA) in 20 (24%). Seventy‐one percent of patients in the HA group corresponded to ASA IV/V, compared with 35% in the group with primary anastomosis (P < 0.001). Patients with Hartmann resection had also a higher MPI (23 ± 8) vs those with primary anastomosis (18 ± 7; P < 0.004). However, differences between the HA group and the PA group due to post‐operative morbidity (21% vs 35%) and mortality (35% vs 20%) did not reach statistical significance. Nevertheless, multivariate analysis of the whole series revealed a significant relationship between MPI and mortality (P < 0.0043), independent of ASA class, age and operative procedure.

Conclusion

Patients assigned to Hartmann procedure had more co‐morbidities and more advanced peritonitis as assessed by increased ASA and higher MPI. The Mannheimer Peritonitis Index proved to be an independent prognostic index in estimating mortality with respect to peritonitis extension and septic status of the patient.
Detection of lymph node metastases in colorectal carcinoma
Authors: O'Dwyer S. T. , Haboubi N. Y. , Johnson J. S. , Gardy R.
Published: March 2003

The detection of lymph node metastases is the single most important prognostic factor for patients with colorectal cancer. This review outlines the difficulties and methods of detecting positive lymph node metastases in this disease. An outline of traditional diagnostic methods including preoperative ultrasound and cross sectional imaging techniques are evaluated alongside newer modalities including immunoscintography and PET scanning and intraoperative radioguided imaging. Pathological methods of detecting positive nodal disease using standard histopathological staging, enhanced lymph node harvesting and determination of micrometastases are also discussed.
Consensus statement of definitions for anorectal physiology and rectal cancer*
Authors: Lowry A. C. , Simmang C. L. , Boulos P. , Farmer K. C. , Finan P. J. , Hyman N. , Killingback M. , Lubowski D. Z. , Moore R. , Penfold C. , Savoca P. , Stitz R. , Tjandra J. J.
Published: March 2003

Introduction from the Editor

An international working party co‐ordinated by Dr Ann Lowry, University of Minnesota, was charged with the task of producing definitions of terms applicable to anorectal physiology and rectal cancer. The consensus achieved is published below and will simultaneously appear in Diseases of Colon and Rectum and in the Australian New Zealand Journal of Surgery. It is essential that there is uniformity in descriptions and it is hoped that the Statement will be generally adopted and become standard terminology.
Surgical resection of colorectal liver metastases
Authors: Memon M. A. , Beckingham I. J.
Published: March 2003

Background

Liver metastases are a major cause of death in patients with colorectal carcinoma. The only curative option available at present is surgery. This review article discusses the current state of evidence for the effectiveness of liver resection for patients with liver metastases from colorectal cancer.

Methods

Medline, Embase, Current Contents and Science Citation Index databases were used to search English language articles published on the subject of liver resection for colorectal metastases in the last 20 years.

Results

Liver resection has a five year survival of 16–49% and 10 year survival of 17–33% with an operative mortality rate of 0–9%. Two factors appear to be clearly associated with poorer outcome – involved resection margins and the presence of extrahepatic disease (including hilar and coeliac axis lymph nodes) at the time of liver resection. None of the other factors related to the patients, their primary tumour or the metastases themselves have been conclusively shown to adversely effect long‐term survival.

Conclusions

Liver resection is a feasible, safe and effective procedure which carries an acceptable morbidity and mortality and does have a major impact on the survival of these patients. The decision on resectability of colorectal metastases should be decided by the ability to leave at least 2–3 segments of liver free from metastases with uninvolved resection margins, together with the general fitness of the patient to undergo a major surgical procedure.