bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐regulation within outbreak populations of feral house mice: a test of alternative models
Authors: SUTHERLAND DUNCAN R. , SINGLETON GRANT R.
Published: March 2006

Outbreaks of feral house mice, Mus domesticus, in Australia represent a fundamental failure of the behavioural control mechanisms of population density, as proposed in the hypothesis of self‐regulation.

Mice have the potential to keep numbers in check via a suite of spacing behaviours; however, the self‐regulation hypothesis implies that some social change occurs that permits the population to erupt. It also suggests that at different phases of an outbreak, distinct patterns of social activity are evident.

We compare predictions from two models encapsulating the self‐regulation hypothesis as applied to feral house mice in south‐eastern Australia. Each model may be distinguished by the timing of aggressiveness between mice that leads to a closed social system. We compare individual turnover, residency and territoriality in each sex and age cohort during the increase, peak and low phases of a population outbreak that peaked in 2001.

The activity of 438 mice was monitored via intensive mark–recapture trapping and an automated event recording system that detected the activity of 300 marked individuals at burrow entrances.

Our findings support the second model, which suggests that mice switch from an almost asocial structure at low densities to a territorial system as abundance increases. Adult females appear more likely than males or juveniles to make the significant social shift. The trigger for this change remains unclear and several alternative mechanisms are proposed.
Silica in grasses as a defence against insect herbivores: contrasting effects on folivores and a phloem feeder
Authors: MASSEY FERGUS P. , ENNOS A. ROLAND , HARTLEY SUE E.
Published: March 2006

Silica, deposited as opaline phytoliths in the leaves of grasses, constitutes 2–5% of dry leaf mass, yet its function remains unclear. It has been proposed that silica may act as an antiherbivore defence by increasing the abrasiveness and reducing the digestibility of grass leaves, although there is little direct experimental evidence to support this.

We investigated the effects of manipulated silica levels on the abrasiveness of the leaves of five grass species. We also examined the effects of silica levels on the feeding preferences, growth performance and digestion efficiency of two folivorous insects and one phloem‐feeding insect.

Silica addition resulted in increases to leaf abrasiveness in four of the five grass species studied. Silica addition also deterred feeding by both folivores and reduced their growth rates and digestion efficiency.

These effects resulted in lower pupal mass of the lepidopteron larvae Spodoptera exempta and compensatory feeding by the orthopteran, Schistocerca gregaria. In contrast, silica had no effects on the feeding preference or the population growth of the phloem feeder, Sitobion avenae.

Our results demonstrate that silica is an effective defence against folivorous insects, both as a feeding deterrent, possibly mediated by increased abrasiveness, and as a digestibility reducer. The effects of silica on pupal mass and development time may impact on herbivore fitness and exposure to natural enemies.

These results are the first demonstration of a direct effect of silica on the abrasiveness of grasses and the adverse impact of silica on herbivore preference and performance.
How moles contribute to colonization success of water voles in grassland: implications for control
Authors: DELATTRE P. , CLARAC R. , MELIS J. P. , PLEYDELL D. R. J. , GIRAUDOUX P.
Published: March 2006

Outbreaks of the water vole Arvicola terrestris cause severe damage in grasslands of upland regions of Europe. The sheer speed of this phenomenon is a challenge to effective pest control measures. While there has been some research into factors that promote outbreaks, especially landscape composition, little is yet known of the biological mechanisms underlying the speed of colonization of grasslands during the population growth stage. Like A. terrestris, the mole Talpa europaea digs vast tunnel networks that may be used by A. terrestris. The availability of extensive networks of this sort might greatly boost the colonization potential of A. terrestris and so explain the speed of onset of its outbreaks.

Areas occupied by networks of A. terrestris and T. europaea tunnels, and their respective locations, were evaluated and mapped with a global positioning system (GPS) during low‐density, growth and the first weeks of abundance phases of cyclic fluctuations of A. terrestris.

During the growth phase and the first weeks of the abundance phase nearly 80% of new A. terrestris colonies were found in T. europaea tunnel networks, although these occupied just 20% of the area under study.

The regulating influence of wooded areas on the risk of outbreaks, which can be identified at larger spatial scales (region, sector), was imperceptible at local scales, probably because of the influence and relative extent of T. europaea tunnel networks.

There was a threshold level of occupancy of grassland by T. europaea, as indexed by surface indices, below which A. terrestris populations were regulated naturally and over long periods.

Synthesis and applications. These findings have implications for controlling outbreaks of A. terrestris. Temporally, chemical pest control of A. terrestris can be reduced by taking action during the A. terrestris low‐density phases, preferably in the autumn. Spatially, control operations should be targeted at T. europaea and early A. terrestris networks. Mechanical destruction of tunnels (e.g. ploughing) and trapping should be considered as an alternative to chemical pest control.
Captive breeding and the fitness of reintroduced species: a test of the responses to predators in a threatened amphibian
Authors: KRAAIJEVELD‐SMIT FEMMIE J. L. , GRIFFITHS RICHARD A. , MOORE ROBIN D. , BEEBEE TREVOR J. C.
Published: March 2006

Although captive breeding and reintroduction is a high‐profile management tool for many threatened species, it is unclear how long‐term captive breeding can influence fitness attributes such as natural defences to predators.

Induced defences that have evolved in the Mallorcan midwife toad Alytes muletensis in response to introduced predators were compared in natural and reintroduced populations that had a common ancestry, and in short‐term and long‐term captive populations that differed in ancestry.

Defences against predators were maintained in a reintroduced population derived from stock that had passed through three to eight generations of captive breeding prior to release into a predator‐free area. Heterozygosity did not differ between natural and reintroduced populations, but the reintroduced population displayed lower allelic richness.

A comparison between populations maintained for different lengths of time in captivity revealed a significant reduction in one defensive trait in stock maintained for more than eight generations. Neutral genetic variation (i.e. heterozygosity and allelic richness) did not differ between the short‐term captive population and a natural population, but there was a significant loss of genetic variation in the long‐term captive population.

Synthesis and applications. The results suggest that relatively high levels of heterozygosity and important fitness attributes can be maintained for a few generations in breeding programmes for threatened species despite small numbers of founders and the absence of natural selection. Nevertheless, both fitness and heterozygosity may eventually start to deteriorate in the long term, and this may have implications for reintroduction strategies.
Potential for multiple lag phases during biotic invasions: reconstructing an invasion of the exotic tree Acer platanoides
Authors: WANGEN STEVEN R. , WEBSTER CHRISTOPHER R.
Published: March 2006

Perennial woody invaders often form persistent patches that significantly alter the structure and composition of native plant communities. Given their long generation times compared with ruderal invaders, these species may experience prolonged establishment phases between successful introduction and spread. Gap dynamics of shade‐tolerant invaders could lead to multiple lag phases during the invasion process.

In order to investigate the potential for long or multiple lag phases, we reconstructed the invasion of Acer platanoides (a shade‐tolerant, invasive, exotic tree) on an 1130‐ha temperate forested island in Lake Huron, USA. We measured and mapped the spatial location of every A. platanoides≥ 0·5 m in height that had successfully established within a 728‐ha forested park on the island. A simple age–diameter relationship, developed from a randomly selected subsample of the population, was used to assign an establishment date to each individual.

Following a 34‐year establishment phase, the area occupied by ≥ 1 A. platanoides ha−1 increased linearly at a rate of 5·6 ha year−1 for 35 years, after which range expansion slowed. Population growth lagged behind range expansion, with rapid population growth associated with infill between parents. During the expansion phase, numerous satellite populations established but contributed little to population growth and spatial expansion because of the long time required for them to become reproductive. These satellite populations will most probably accelerate population growth and spread once they reach reproductive age.

Roads and trails provided important corridors for propagule movement away from developed areas over the course of the invasion. They also appeared to facilitate longer distance dispersals than would be expected given the biology of the species.

Synthesis and application. Our results suggest that shade‐tolerant invaders with long generation times may undergo long establishment phases as well as periodic lags during the expansion phase. These lags may provide windows of opportunity for control but could easily be misinterpreted as signs that the population has reached an equilibrium density or the geographical extent of its spread. Additionally, roads and trails may provide important corridors for movement of propagules via non‐standard means of dispersal.
Predicting time‐specific changes in demographic processes using remote‐sensing data
Authors: RASMUSSEN HENRIK B. , WITTEMYER GEORGE , DOUGLAS‐HAMILTON IAIN
Published: March 2006

Models of wildlife population dynamics are crucial for sustainable utilization and management strategies. Fluctuating ecological conditions are often key factors influencing both carrying capacity, mortality and reproductive rates in ungulates. To be reliable, demographic models should preferably rely on easily obtainable variables that are directly linked to the ecological processes regulating a population.

We compared the explanatory power of rainfall, a commonly used proxy for variability in ecological conditions, with normalized differential vegetation index (NDVI), a remote‐sensing index value that is a more direct measure of vegetation productivity, to predict time‐specific conception rates of an elephant population in northern Kenya. Season‐specific conception rates were correlated with both quality measures. However, generalized linear logistic models compared using Akaike's information criteria showed that a model based on the NDVI measure outperformed models based on rainfall measures.

A predictive model based on coarse demographic data and the maximum seasonal NDVI value was able to trace the large variation in observed season‐specific conception rates (Range 0–0·4), with a low median deviation from observed values of 0·07.

By combining the model of season‐specific conception rates with the average seasonal distribution of conception dates, the monthly number of conceptions (range 0–22) could be predicted within ±3 with 80% confidence.

Synthesis and applications. The strong predictive power of the normalized differential vegetation index on time‐specific variation in a demographic variable is likely to be generally applicable to resource‐limited ungulate species occurring in ecologically variable ecosystems, and could potentially be a powerful factor in demographic population modelling.
The modelled effects of differing fire management strategies on the conifer Callitris verrucosa within semi‐arid mallee vegetation in Australia
Authors: BRADSTOCK R. A. , BEDWARD M. , COHN J. S.
Published: March 2006

Callitris verrucosa is an obligate‐seeder co‐dominant within flammable semi‐arid mallee shrublands in southern Australia. We sought to determine if there is an optimal management solution that provides both a significant reduction in wildfire size and maintains a viable population of C. verrucosa. Using a spatial model, the effects of alternative fire management strategies (pattern and level of prescribed burning) on populations of C. verrucosa were simulated.

Plant dynamics and fire propagation were simulated in a gridded landscape model (104 cells, c. 1 ha) incorporating topographic variation typical of dune landscapes. Fire propagation was governed by fuel age, and topographic and weather effects, incorporating potential for spot fires and the influence of wind direction. Plant dynamics were determined by known demographic parameters for C. verrucosa.

The size of unplanned fires declined significantly as a function of increasing prescribed burning level. Mean fire interval was longer at zero or 1% per year of landscape treated with prescribed fire than at higher levels of prescribed burning. Mean fire intervals were shorter under the highest probability of unplanned ignition in the flat landscape and in the dune landscape on the slopes.

The responses of C. verrucosa populations reflected trends in fire intervals as affected by prescribed burning levels/patterns and topography. The lowest population sizes resulted from either high (20% per year) or zero prescribed burning. The highest population sizes occurred consistently at an intermediate level of prescribed ignition (5% per year). Population sizes were significantly larger in dune vs. flat landscapes and under random vs. non‐random prescribed ignition patterns.

Synthesis and applications. The use of prescribed fire to achieve management objectives concerning ‘wildfire control’ and conservation will involve trade‐offs that are affected by landscape characteristics. Prescribed fire is predicted to achieve both a diminution of wildfire size and maintenance of C. verrucosa population in the landscape. The trade‐off required to achieve these objectives concerns the appropriate level and pattern of prescribed fire (strategy).
Is management of an invasive grassAgropyron cristatumcontingent on environmental variation?
Authors: HANSEN MALIN J. , WILSON SCOTT D.
Published: March 2006

The control of invasive species is a challenge heightened by the dependency of management outcomes on environmental variation. This is especially true for plants invading semi‐arid habitats, where growing season precipitation varies greatly among years.

Agropyron cristatumis an invasive grass widely introduced in the Great Plains of North America. We studied its demographic responses to management using field experiments and matrix population models. Plants were clipped to simulate grazing, treated with herbicide or left unmanaged, at three levels of water availability, for 2 years.

Growth rates (λ) were high in unmanaged populations. Clipped populations were mainly stable, whereas λ for herbicide‐treated populations varied greatly with water availability and between years. Low λ in clipped and herbicide‐treated populations was mainly the result of low seed production, and these populations were the most sensitive to water availability.

Clipped populations produced no seeds in the second year, indicating a cumulative negative effect of defoliation. In general, seed production, germination and juvenile survival all increased with water supply, suggesting that invasion may increase under wet conditions.

Population projections revealed a steady increase in population size for unmanaged populations, whereas clipped populations were more stable. Herbicide‐treated populations mainly decreased. Life‐cycle stages associated with recruitment contributed the most to the rapid growth of unmanaged populations, whilst the persistence of managed populations relied on the survival of established tussocks.

Synthesis and applications.These results demonstrate strong management effects onA. cristatuminvasion in spite of significant population responses to water availability. Management can therefore have large effects on the invasion of native grasslands regardless of among‐year variability in precipitation.
Unpalatable plants facilitate tree sapling survival in wooded pastures
Authors: SMIT CHRISTIAN , DEN OUDEN JAN , MÜLLER‐SCHÄRER HEINZ
Published: March 2006

In endangered wooded pasture ecosystems established tree saplings are frequently found in spatial association with protective structures, suggesting nurse effects. This associational resistance is thought to be a driving force behind tree regeneration in wooded pastures. Experimental evidence for associational resistance is, however, scarce. We studied the effects of unpalatable plants on tree sapling performance in a wooded pasture ecosystem in Switzerland and tested the associational resistance hypothesis experimentally.

We transplanted 600 Picea abies saplings of two size classes (5 cm and 10 cm) in plots: (i) with unpalatable plants (either Gentiana lutea or Cirsium acaule, representing a chemically and mechanically defended species, respectively); (ii) with one of both unpalatable plants clipped to the ground; and (iii) without any unpalatable plants. Grazing intensity was measured once in each plot and tree sapling performance was followed for 2 consecutive years.

Grazing intensity was significantly higher in plots without unpalatable plants, and significantly higher in plots with Cirsium than with Gentiana. Correspondingly, sapling survival (21·5% and 10·6% after 1 and 2 grazing years, respectively) was significantly higher near unpalatable plants, and significantly higher in plots with Gentiana than with Cirsium. Large tree saplings survived significantly better than small ones, and depended less on the unpalatable plants for survival.

Except for saplings planted near Gentiana, sapling removal by cows and horses was the major cause of death, the extent varying between unpalatable species and treatments.

The growth in height of the saplings was unaffected by the treatments.

Synthesis and applications. This study shows that unpalatable plants can enhance tree regeneration in wooded pastures. Sapling survival was significantly higher near unpalatable plants where grazing intensity was significantly lower. Protection against cattle is particularly important for small saplings. These results have important management implications for the endangered and disappearing wooded pastures in western Europe. Transplanting tree saplings near unpalatable plants could be an alternative reforestation technique in intensively grazed wooded pastures. On the other hand, removal of unpalatable plants and shrubs might prevent or slow down undesired tree encroachment in less intensively grazed areas.
Gradients in vegetation cover, structure and species richness of Nama‐Karoo shrublands in relation to distance from livestock watering points
Authors: TODD SIMON W.
Published: March 2006

Gradients of animal impact known as piospheres tend to develop around artificial watering points, particularly in arid zones. Such grazing gradients represent a potential opportunity for differentiating the long‐term effects of livestock activity from other environmental patterns. In this study, the impact of watering point provision on the plant cover, species richness and community structure of Karoo shrublands, South Africa, was investigated in the context of the evolutionary history and current grazing management practices of the region.

The impacts of watering point provision were investigated by sampling plant cover and composition along transects placed at set distances, ranging from 10 m to 2200 m, from 11 watering points.

Karoo vegetation cover and structure are relatively resilient to livestock grazing. Karoo plant diversity, as measured by species richness, evenness and dominance, was not as resilient. Twice as many species decreased as increased near watering points. The majority of species that decreased were regarded as being highly palatable to livestock. Heavy grazing, leading to death or repeated reproductive failure, is the most likely mechanism leading to the decline of such species.

The highly disturbed area immediately adjacent to watering points was dominated by forbs and contained a large proportion of alien species. Adjacent to this was a zone dominated by widespread shrub species of medium to low palatability. Areas most distant from watering points contained a greater proportion of species known to be highly palatable to livestock. The ability of dominant Karoo shrubs to tolerate heavy grazing may have allowed rangeland managers to maintain stocking rates above that which can be tolerated by the majority of species but which are supported by a minority of grazing‐tolerant species.

Synthesis and applications. Highly palatable species are more abundant in areas distant from water points. Larger paddocks therefore provide a refuge for sensitive species that might otherwise be lost from the rangeland as a whole. Species that tend to occur away from watering points represent potentially useful indicators of grazing pressure. The use of these species as indicators of rangeland condition among landowners should be promoted.
To graze or not to graze? Sheep, voles, forestry and nature conservation in the British uplands
Authors: EVANS DARREN M. , REDPATH STEPHEN M. , ELSTON DAVID A. , EVANS SHARON A. , MITCHELL RUTH J. , DENNIS PETER
Published: March 2006

The British uplands are internationally important for their unique plant and bird communities. They have considerable economic, nature conservation, landscape, aesthetic and tourism‐related value and as a result are under a variety of different pressures, most notably from sheep farming, shooting interests, commercial forestry and conservation interests.

In order to optimize biodiversity in the uplands, the challenge is to find how to balance the different land‐use pressures. One key upland species that is potentially affected by livestock grazing, and is of considerable interest to both foresters and nature conservationists, is the field vole Microtus agrestis. Relaxation of livestock grazing can result in an increase in vole numbers. This in turn could have both positive and negative implications for biodiversity as (i) field voles are a major source of prey for other species and (ii) they are a cause of damage to newly planted trees and potentially damaging in areas of native woodland regeneration.

A replicated, randomized block experiment, consisting of six replicates of four livestock grazing treatments, was established in 2003 (with baseline data collected in 2002). This enabled us to examine the effects of livestock grazing on field vole abundance.

We have demonstrated experimentally for the first time that livestock grazing pressure affects the abundance of field voles (as measured by a vole sign index) in the uplands. In the first year of the experiment, immediate treatment effects were detectable, with a lower abundance of voles in the conventionally grazed treatment compared with those in the ungrazed treatment, and with intermediate vole abundances in the lightly grazed treatments. The significant treatment effects became more apparent in 2004, with a higher abundance of voles in the extensively grazed mixed treatment (i.e. sheep and cattle) than in the extensively grazed treatment that contained only sheep.

Synthesis and applications. In order to maximize biodiversity in the uplands, our results suggest that low intensity livestock grazing, used in a novel ways, could be a useful management tool to reduce vole abundance (and hence subsequent tree damage) compared with excluding livestock from young plantations completely. Furthermore, vole abundance would be higher at low grazing intensity compared with conventional stocking rates, thus still providing food for raptors and other vole‐eating vertebrates. Indeed, low‐intensity sheep and mixed livestock grazing might improve prey availability as a direct consequence of increased heterogeneity in vegetation structure. Our results suggest that it may be possible to maintain the open character of moorland habitats, and benefit key upland species generally, by reducing sheep grazing pressure and introducing low‐intensity mixed livestock grazing throughout the uplands.
Modes of imprinted gene action in learning disability
Authors: Isles A. R. , Humby T.
Published: March 2006

Background  It is now widely acknowledged that there may be a genetic contribution to learning disability and neuropsychiatric disorders, stemming from evidence provided by family, twin and adoption studies, and from explicit syndromic conditions. Recently it has been recognized that in some cases the presentation of genetic syndromes (or discrete aspects of disorders) is dependent on the sex of the transmitting parent. Such ‘parent‐of‐origin effects’ can be explained by a number of genetic mechanisms, a predominant one of which is genomic imprinting. Genomic imprinting refers to the parent of origin‐specific epigenetic marking of an allele of a gene, such that for some genes it is mainly the maternally inherited allele only that is expressed, whereas for others expression occurs mainly from the paternal copy.

Methods  Here we discuss the contribution of imprinted genes to mental dysfunction and learning disability, using clinical examples of association studies and explicit imprinting disorders (with particular emphasis to Angelman and Prader–Willi syndromes), and evidence from animal work.

Results  Clinical and animal studies strongly suggest that imprinted genes contribute to brain functioning, and when the genes or epigenetic processes are disrupted, this can give rise to neuropsychiatric problems. Another system to which imprinted genes provide a large contribute is the placenta and foetal development. Epidemiological studies suggest that this is also a key area in which dysregulation can give rise to learning difficulties.

Conclusions  Disruption of imprinted genes, or the epigenetic processes controlling them, can contribute to learning disability. These effects can be divided into two types: direct effects, such as those seen in explicit imprinting disorders such as Angelman and Prader–Willi syndromes, and indirect effects as manifest via changes in foetal programming.
Phylogenetic analysis ofCulicoidesspecies from France based on nuclear ITS1‐rDNA sequences
Authors: Perrin A. , Cetre‐Sossah C. , Mathieu B. , Baldet T. , Delecolle J.‐C. , Albina E.
Published: March 2006

Abstract. Biting midges of the genusCulicoides(Diptera: Ceratopogonidae) play important roles in the transmission of viral diseases affecting wild and domestic ruminants and horses, including Bluetongue (BT) and African horse sickness (AHS) respectively. In southern Europe, BT has been largely transmitted by the classical Afro‐Asian vectorCulicoides imicolaKieffer. However, other species such asC. obsoletusMeigen,C. scoticusDowns & Kettle andC. pulicarisLinné may also be involved in BTV transmission. As a consequence of the discovery ofC. imicolafollowed by BTV‐2 outbreaks on the island of Corsica in October 2000, further studies on these biting midges have been carried out. To better characterize the evolution and phylogenetic relations ofCulicoides, molecular analysis in parallel with a morphology‐based taxonomic approach were performed. Phylogenetic analyses of FrenchCulicoidesspecies were undertaken using the ribosomal DNA (rDNA) internal transcribed spacer 1 (ITS1) as a molecular target. This region was shown to be useful in understanding evolutionary and genetic relationships between species. Construction of several trees showed that molecular phylogeny within the genusCulicoidescorrelates not only with morphological‐based taxonomy but also with ecological patterns.
Clinical significance of hiatal hernia in the development of gastroesophageal reflux after distal gastrectomy for cancer of the stomach
Authors: Fujiwara Yoshinori , Nakao Koji , Inoue Takashi , Koishi Kenji , Nishio Yoshimasa , Yagyu Ryuichirou , Nakagawa Kazuhiko , Yamamura Takehira
Published: March 2006

Background and Aims:  The relationship between gastroesophageal reflux disease and sliding hernia is controversial, especially following distal partial gastrectomy in patients with gastric cancer. The aim of this study was to examine the relationship between gastroesophageal reflux disease and sliding hernia of the esophagus after distal gastrectomy using the gastroesophageal scintigraphy and endoscopy.

Methods:  Forty‐five distal gastrectomy patients diagnosed with cancer of the stomach were studied. Twenty‐five patients presented with reflux symptoms, such as heartburn and/or regurgitation and 20 patients exhibited no reflux symptoms. All of the patients were examined by gastroesophageal scintigraphy and their reflux indices were determined. Thirty‐eight of the patients underwent upper endoscopy and both sliding hernias and reflux symptoms were classified as mild or severe.

Results:  Sliding hernias were diagnosed in all of the subjects and 65.8% of the patients exhibited reflux symptoms. Evidence of endoscopic esophagitis was noted in only 39.5% of the patients. The reflux indices for the mild and severe hernia groups were 5.03 ± 2.2 and 10.3 ± 6.4, respectively (P < 0.05). More severely symptomatic esophagitis was prevalent in the severe hernia group in comparison to the mild group (P < 0.05).

Conclusion:  The results suggest that the onset of gastroesophageal reflux after distal gastrectomy is induced by the surgical procedures and that hiatal hernia may be an important factor in the etiology of reflux esophagitis.
Ultrasonographic evaluation of gallbladder functions in patients with irritable bowel syndrome
Authors: Güçlü Mustafa , Pourbagher Ali , Serin Ender , Kul Kemal , Özer Birol , Cosar Arif , Içer M Okan , Gür Gürden , Boyacioglu Sedat
Published: March 2006

Background:  The aim of the present study was to evaluate gallbladder function in irritable bowel syndrome (IBS) patients.

Methods:  The functions of gallbladder were investigated every 30 min for 4 h. In addition, ejection fraction of the gallbladder was calculated from the fasting and post‐prandial volumes.

Results:  In IBS patients and healthy controls, fasting gallbladder volumes were 19.64 ± 3.09 mL and 20.04 ± 1.82 mL, and residual volumes after 3 h were 3.36 ± 6.82 mL and 9.74 ± 1.50 mL. Except for the residual volume after 3 h, all these results were not statistically significant. Residual volume after 3 h was statistically significantly lower in the IBS patients than in the controls (P < 0.001). Ejection fraction of the gallbladder was significantly higher in the IBS patients than in the controls (84% vs 55%, P < 0.001).

Conclusions:  Gallbladder contraction in patients with IBS was not different from that of a control group at post‐prandial second hour but was signigicantly more pronounced at the end of 3 h when compared with controls. Ejection fraction of the gallbladder was higher in IBS patients when compared with controls.
Association between hepatitis A virus and Helicobacter pylori in a developing country: The saga continues
Authors: Bizri Abdul Rahman N , Nuwayhid Iman A , Hamadeh Ghassan N , Steitieh Souzan W , Choukair Ali M , Musharrafieh Umayya M
Published: March 2006

Background:   The epidemiologic association between Helicobacter pylori and hepatitis A virus (HAV) has been evaluated by various different groups with conflicting conclusions. The aim of the present study was to determine the prevalence of HAV and H. pylori infection among adolescents attending high schools in Lebanon, and to identify the sociodemographic factors associated with their prevalence, individually and concurrently.

Methods:   Nine hundred and two school students 14–18 years of age were selected randomly from 30 schools scattered all over Lebanon and tested for IgG antibodies against hepatitis A and H. pylori. Each student received a copy of a self‐administered questionnaire to be completed by his/her parents inquiring about demographics, history of immunization, and prior viral hepatitis illness in the student. Bivariate analysis examined the association between different sociodemographic variables and prior HAV or H. pylori infection, and multivariate regression analysis was done to determine the factors independently associated with prior infection.

Results:   Using ELISA the seroprevalence of antibodies against HAV was 71.3% as compared to 61.6% for anti‐H. pylori. A total of 9.1% of those tested were negative for both agents. A multinomial regression analysis revealed that place of residence in relation to district or urban versus rural areas, in addition to mothers’ education, were important determinants for the incidence of both agents.

Conclusion:   The low number of subjects negative for both H. pylori and HAV antibodies in Lebanon is indicative of their high prevalence in the country. It is possible that this high prevalence reflects an age‐specific prevalence rather than a true association.
Expression of gamma‐aminobutyric acid and glutamic acid decarboxylases in rat descending colon and their relation to epithelial differentiation
Authors: WANG Fang Yu , ZHU Ren Min , MAEMURA Kentaro , HIRATA Ichiro , KATSU Ken‐ichi , WATANABE Masahito
Published: March 2006

OBJECTIVE:  To detect the expression of gamma‐aminobutyric acid (GABA) and glutamic acid decarboxylases (GADs; including two isoforms GAD65 and GAD67) in the epithelial growth zones of the descending colon in rats, and to investigate their relation to epithelial differentiation and proliferation.

METHODS:  The expression of GABA and GADs in rat descending colon was investigated by immunofluorescent staining and confocal laser scanning techniques, and goblet cells were further investigated by wheat‐germ agglutinin histochemistry. In addition, GAD65 and GAD67 mRNAs were also detected by reverse transcription‐polymerase chain reaction. Furthermore, evaluation of cell kinetics in colonic epithelia was conducted by ABC immunostaining using a monoclonal antibody against proliferating cell nuclear antigen (PCNA).

RESULTS:  Immunoreactive GABA and GADs were distributed in the upper third of the crypts and at the luminal surface in the rat descending colon. Strong staining for GABA and GADs was localized mainly in the cytoplasm of epithelial cells near the neck of the crypts and along the luminal surface. In addition, GABA and GAD65 were also detected at the lamina propria in colonic mucosa. No staining for GABA or GADs was found in goblet cells. GAD65 and GAD67 mRNAs were identified in homogenates of rat descending colon. PCNA labeled nuclei were found in the lower two‐thirds of the crypts.

CONCLUSIONS:  The expression of GABA and GADs in the maturation and function zones of rat descending colon suggests that GABA may be involved in the differentiation of colonic epithelial cells.
Effect of change in an inhibitory neurotransmitter of the myenteric plexus on the pathogenetic mechanism of irritable bowel syndrome subgroups in rat models
Authors: XU Jun Rong , LUO Jin Yan , SHANG Lei , KONG Wu Ming
Published: March 2006

OBJECTIVE:  In order to investigate the effect of change in an inhibitory neurotransmitter of the myenteric plexus on irritable bowel syndrome (IBS) subgroups, the amounts of nitric oxide (NO) in constipation‐predominant (C‐IBS) and diarrhea‐predominant (D‐IBS) IBS models in rats were studied.

METHODS:  The D‐IBS model was created in rats by intracolonic instillation of acetic acid and by restraint stress. The D‐IBS control group underwent intracolonic instillation with saline instead. The C‐IBS model was created in rats by gastric instillation of 0–4°C cool water daily for 14 days. The C‐IBS control group underwent gastric instillation with saline instead. A blank control group was also made. Viscerosomatic sensitivity was assessed with electromyographic (EMG). Abdominal contractions induced by distension of a colonically inserted balloon (0–1.6 mL) was recorded in rats by implanting electrodes in the abdominal external oblique muscle. An India ink gastric instillation experiment was used to detect the bowel movement and fecal pellets formation. Histological analysis of colonic tissue was performed. Nicotinamide dinucleotide phosphate (NADPH)‐diaphorase staining was used to detect positive NO neurons in the myenteric plexus.

RESULTS:  When the balloon was distended by high volume, there were significantly more contractions of abdominal muscle in D‐IBS compared with C‐IBS and the control groups (P < 0.05). When the balloon was distended by low volume, there were significantly fewer contractions of abdominal muscle in C‐IBS compared with D‐IBS and the control groups (P < 0.05). The wet weight and water content of the feces expelled by the rats in the C‐IBS and the C‐IBS control groups were significantly lower than those in the blank control group (P < 0.05). The time before the first black stool in the C‐IBS group was significantly longer than that in the blank control group and C‐IBS control group (P < 0.05). Histological analysis of the colon showed no colonic inflammation in any group. The number of NO‐positive neurons in the C‐IBS group was significantly greater than in the D‐IBS and control groups (P < 0.01), although there was no significant difference in the number of neurons between the D‐IBS and the control groups (P > 0.05).

CONCLUSIONS:  Enhanced inhibitory neurotransmitter NO in the myenteric plexus of the colon is related to IBS subgroups, visceral sensitivity and motility dysfunction. The results reveal that NO plays a role in the pathogenetic mechanism of IBS subgroups.
Evaluating the role of serum elastase 1 in the diagnosis of pancreatic cancer
Authors: WU Dong , QIAN Jia Ming , DENG Rui Xue , JIANG Wei Jun , CHEN Yuan Jia , LIU Xiao Hong , LU Xing Hua
Published: March 2006

OBJECTIVE:  To determine the normal value of serum elastase 1 in Chinese adults and evaluate its diagnostic value for pancreatic cancer.

METHODS:  Serum elastase 1 and CA19‐9 were measured in 132 samples, including 39 patients with pancreatic cancer, 48 with other gastrointestinal malignancy, 24 with gastrointestinal benign disease and 21 healthy adults as normal control. Multiple statistical methods including receiver operating characteristics curve and discriminant analysis were employed.

RESULTS:  The established normal range of serum elastase 1 in Chinese adults was found to be under 4.36 mg/L. Serum elastase 1 increased markedly in patients with pancreatic carcinoma of smaller size and/or located in the pancreatic head. The sensitivity, specificity and overall accuracy of elastase 1 for diagnosis of pancreatic cancer were 61.5%, 75.3% and 71.2%, respectively, as compared with 71.8%, 73.1% and 72.7% for CA19‐9. Discriminant analysis can improve the sensitivity and overall accuracy of elastase 1 to 82.0% and 74.2%, respectively, with a slight decline in the specificity to 71.0%.

CONCLUSIONS:  The cutoff value of serum elastase 1 in normal Chinese adults is 4.36 mg/L. Serum elastase 1 is effective in the diagnosis of pancreatic cancer, especially for those of smaller size or in the pancreatic head. Use of appropriate statistical methods can help to make the diagnosis more accurate.
Diet and gastric cancer: a case–control study in Shanghai urban districts
Authors: FEI Su Juan , XIAO Shu Dong
Published: March 2006

OBJECTIVE:  The incidence rates of gastric cancer in Shanghai urban districts have been markedly declining over the past three decades. From 1972 to 2001 the age‐adjusted incidence rates of gastric cancer decreased from 62.0 to 32.5 per 100 000 in men and from 23.9 to 16.9 per 100 000 in women. This study aimed to investigate the relationship between environmental factors, in particular dietary factors, and the development of gastric cancer in those who lived in Shanghai urban districts for more than 15 years, and to explore the causes that led to the reduction of the incidence rates of gastric cancer in Shanghai.

METHODS:  One hundred and eighty‐nine patients with gastric cancer and 567 age and sex‐matched controls were surveyed with a questionnaire. SPSS software package was used to perform the univariate and multivariate unconditional logistic regression analysis modeling.

RESULTS:  Vitamin supplements, use of home refrigerators, high consumption of fresh fruits and vegetables, bean and dairy products, and good meal habits were protective factors against gastric cancer. However, family history of cancer, chronic gastric diseases, increased intake of salted, pickled, fried and smoked foods, poor meal habits, smoking and alcohol drinking were risk factors for gastric cancer.

CONCLUSIONS:  The reduction of the incidence of gastric cancer in Shanghai urban district in the past three decades is closely related to environmental factors, in particular dietary factors and wide use of home refrigerators.
Analysis of gene expression profile in colon cancer using the Cancer Genome Anatomy Project and RNA interference
Authors: HUANG Zhi Gang , RAN Zhi Hua , LU Wei , XIAO Shu Dong
Published: March 2006

OBJECTIVE:  To investigate the changes in the gene expression profile in colon cancer to further identify gene markers that may be useful in the management of this disease.

METHODS:  Data from serial analysis of gene expression (SAGE) collected by the Cancer Genome Anatomy Project (CGAP) were used to detect the difference in gene expression between normal tissue and colon cancer, and were further confirmed in a sample of 20 patients using RT‐PCR. To identify the functions of differential genes in regulating the cell growth of colon cancer, RNA interference (RNAi) was used to block one of these genes in the colon cancer cell line HCT‐116.

RESULTS:  Expression changes of greater than twofold in two SAGE libraries of colon cancer compared to two of normal tissue were observed for 216 tags of a total of 195 160 transcript tags (54 up‐regulated genes and 136 down‐regulated genes). Subsequent analysis of 17 genes by RT‐PCR confirmed the reliability of this analysis. RNAi‐mediated blockage of one of these genes, transforming growth factor (TGF)β1, significantly reduced the growth of a colon cancer cell line.

CONCLUSIONS:  The combination of CGAP analysis and RNAi provides an excellent system to rapidly define the specific genes that are up‐regulated in cancer to impact the growth of cancer cells. Further study on these differential overexpressed genes may provide gene markers for the detection and treatment of colon cancer.
Advances in mechanisms of postsurgical gastroparesis syndrome and its diagnosis and treatment
Authors: DONG Ke , YU Xiao Jiong , LI Bo , WEN Er Gang , XIONG Wei , GUAN Quan Lin
Published: March 2006

Postsurgical gastroparesis syndrome (PGS) is a complex disorder characterized by post‐prandial nausea and vomiting, and gastric atony in the absence of mechanical gastric outlet obstruction, and is often caused by operation at the upper abdomen, especially by gastric or pancreatic resection, and sometimes also by operation at the lower abdomen, such as gynecological or obstetrical procedures. PGS occurs easily with oral intake of food or change in the form of food after operation. These symptoms can be disabling and often fail to be alleviated by drug therapy, and gastric reoperations usually prove unsuccessful. The cause of PGS has not been identified, nor has its mechanism quite been clarified. PGS after gastrectomy has been reported in many previous studies, with an incidence of approximately 0.4–5.0%. PGS is also a frequent complication of pylorus‐preserving pancreatoduodenectomy (PPPD), and the complication occurs in the early postoperative period in 20–50% of patients. PGS caused by pancreatic cancer cryoablation (PCC) has been reported about in 50–70% of patients. Therefore, PGS has a complex etiology and might be caused by multiple factors and mechanisms. The frequency of this complication varies directly with the type and number of gastric operations performed. The loss of gastric parasympathetic control resulting from vagotomy contributes to PGS via several mechanisms. It has been reported that the interstitial cells of Cajal (ICC) may play a role in the pathogenesis of PGS. Recent studies in animal models of diabetes suggest specific molecular changes in the enteric nervous system may result in delayed gastric emptying. The absence of the duodenum, and hence gastric phase III, may be a cause of gastric stasis. It was thought that PGS after PPPD might be attributable, at least in part, to delayed recovery of gastric phase III, due to lowered concentrations of plasma motilin after resection of the duodenum. The damage to ICC might play a role in the pathogenesis of PGS after PCC, for which multiple factors are possibly responsible, including ischemic and neural injury to the antropyloric muscle and the duodenum after freezing of the pancreatoduodenal regions or reduction of circulating levels of motilin. As the treatment of gastroparesis is far from ideal, non‐conventional approaches and non‐standard medications might be of use. Multiple treatments are better than single treatment. This article reviews almost all the papers related to PGS from various journals published in English and Chinese in recent years in order to facilitate a better understanding of PGS.
Per‐oral transgastric abdominal surgery
Authors: KO Chung‐Wang , KALLOO Anthony N
Published: March 2006

Laparoscopic surgery has several advantages over traditional surgery because it has been shown to be less invasive. The next logical step in the evolution of minimally invasive surgery may be to eliminate all abdominal incisions. The natural orifices provide a port of entry via the gastrointestinal tract to the peritoneal cavity. This approach would require the creation of a perforation, which is considered to be a major complication of endoscopy with significant morbidity and mortality. However, there are several recent studies that have described the technical feasibility and safety of a per‐oral transgastric approach to the peritoneal cavity using conventional endoscopes. Theoretically, this approach could reduce postoperative abdominal wall pain, wound infection, hernia formation, and adhesions. This article aims to summarize the current status of transgastric surgery, currently referred to as natural orifice transluminal endoscopic surgery (NOTES), and to address some of its future challenges.
How prevalent are pH‐specialist diatoms? A reply to Telford et al. (2006)
Authors: Pither Jason , Aarssen Lonnie W.
Published: March 2006

Telford, Vandvik and Birks (2006) (henceforth TVB) refute our conclusion (Pither & Aarssen 2005) that only a minority of fossil diatom taxa within a diverse regional assemblage are pH specialists. They argue that the null model we used exhibited high Type II error rates for both geographically rare taxa (i.e. few lakes occupied) and for acid‐optima taxa, and assert that many more taxa would have been designated specialist had we adequate statistical power, and had more acidic lakes been sampled. However, TVB base their conclusions upon the results of additional analyses, which assume a priori that all taxa are pH specialists. Experimental and observational evidence do not support this assumption. As such, we contend that TVBs criticisms are unjustified.