bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in natural selection for growth and phlorotannins in the brown alga Fucus vesiculosus
Authors: Jormalainen V. , Honkanen T.
Published: June 2004

Directional selection for plant traits associated with resistance to herbivory tends to eliminate genetic variation in such traits. On the other hand, balancing selection arising from trade-offs between resistance and growth or spatially variable selection acts against the elimination of genetic variation. We explore both the amount of genetic variation and variability of natural selection for growth and concentration of phenolic secondary compounds, phlorotannins, in the brown alga Fucus vesiculosus. We measured variation in selection at two growing depths and two levels of nutrient availability in algae that had faced two kinds of past growing environments. Genetic variation was low for growth but high for phlorotannins. The form and strength of selection for both focal traits depended on the past growing environment of the algae. We found strong directional selection for growth rate in algae previously subjected to higher ultraviolet radiation, but not in algae previously subjected to higher nutrient availability. Stabilizing selection for growth occurred especially in the deep growing environment. Selection for phlorotannins was generally weak, but in some past-environment–current-environment combinations we detected either directional selection against phlorotannins or stabilizing selection. Thus, phlorotannins are not selectively neutral but affect the fitness of F. vesiculosus. In particular, there may be a fitness cost of producing phlorotannins, but the realization of such a cost varies from one environment to another. Genetic correlations between selective environments were high for growth but nonexistent for phlorotannins, emphasizing the high phenotypic plasticity of phlorotannin production. The highly heterogeneous selection, including directional, stabilizing, and spatially variable selection as well as temporal change in selection due to responses to past environmental conditions, probably maintains a high amount of genetic variation in phlorotannins. Such variation provides the potential for rapid evolutionary response of phlorotannins under directional selection.
Condition-dependent traits and the capture of genetic variance in male advertisement song
Authors: Brandt L. S. E. , Greenfield M. D.
Published: June 2004

The occurrence of additive genetic variance (VA) for male sexual traits remains a major problem in evolutionary biology. Directional selection normally imposed by female choice is expected to reduce VA greatly, yet recent surveys indicate that a substantial amount remains in many species. We addressed this problem, also known as the ‘lek paradox’, in Achroia grisella (Lepidoptera: Pyralidae), an acoustic moth in which males advertise to females with a pulsed ultrasonic song. Using a standard half-sib/full-sib breeding design, we generated F1 progeny from whom we determined VA and genetic covariance (COVA) among seven traits: three song characters, an overall index of song attractiveness, nightly singing period, adult lifespan, and body mass at adult eclosion. Because A. grisella neither feed nor drink as adults, the last trait, eclosion body mass, is considered a measure of ‘condition’. We found significant levels of VA and narrow-sense heritabilities (h2) for all seven traits and significant genetic correlations (= COVAi,j /√(VA i·VA j)) between most pairs of traits (i, j). Male attractiveness was positively correlated with body mass (condition), adult lifespan, and nightly singing period, which we interpret as an energy constraint preventing males in poor condition from singing attractively, from singing many hours per night, and from surviving an extended lifespan. The positive genetic correlation (r = 0.79) between condition and attractiveness, combined with significant levels of VA for both traits, indicates that much of the variation in male song can be explained by VA for condition. Finally, we discuss the morphological and physiological links between condition and song attractiveness, and the ultimate factors that may maintain VA for condition.
Behavioural interactions, kin and disease susceptibility in the bumblebee Bombus terrestris
Authors: Mallon Eamonn B. , Schmid-Hempel Paul
Published: June 2004

Behavioural interactions are often analysed in terms of their costs and benefits to the actors [Hamilton, (1964) J. Theor. Biol.7 1–16; Gadagkar, (1993) Trends Ecol. Evol.8 232–234; Foster et al., (2001) Ann. Zool. Fenn.38 229–238]. Using the bumblebee Bombus terrestris, we wish to distinguish between two possible determinants of interaction behaviour between conspecifics, namely kin-directed behaviour that reflects genetic distance between individuals, or, alternatively, interactions guided by a functional distance between individuals, specifically, with respect to disease susceptibility. We find no relationship between contact rate of individuals and the genetic distance of their respective colonies. Interestingly, we do find a significant negative correlation between contact rate and the distance between the two colonies in susceptibility to a spectrum of parasite strains. This cannot be explained by either of the a priori alternatives so we propose two further testable hypotheses to explain our results.
Phenotypic correlations among fitness and its components in a population of the housefly
Authors: Reed D. H. , Bryant E. H.
Published: June 2004

An individual's or a population's fitness is the result of a large number of interacting life history traits and the environment. Little information is available on the phenotypic correlations among fitness components and fitness itself, especially outside of Drosophila melanogaster. We also lack detailed information on trade-offs among life history traits. Here we present the relationship between adult progeny production and eight components of fitness, as well as some observed trade-offs between life history traits in the housefly (Musca domestica). We briefly discuss some of the ramifications of these relationships.
The cost of immunity in the yellow fever mosquito, Aedes aegypti depends on immune activation
Authors: Schwartz A. , Koella J. C.
Published: June 2004

Although host immunity offers the obvious benefit of reducing parasite infection, it is often traded-off with other fitness components. We investigated whether the cost of an immune response in the yellow fever mosquito, Aedes aegypti, is modulated by the antigen that activates the melanization immune response. Thus, one of three different novel antigens were injected into the mosquito's thorax – either a glass bead, a negatively charged (C-25) Sephadex bead, or a neutral (G-25) Sephadex bead – and fecundity and bead melanization were observed. Glass beads are immunologically inert and were therefore used as an inoculation control. The fecundity of mosquitoes inoculated with these beads did not differ from the fecundity of mosquitoes that did not melanize negatively charged or neutral beads. The ability of A. aegypti to melanize negatively charged Sephadex beads was associated with reduced fecundity, showing a clear cost of immunity. In contrast, melanization of the neutral beads was quite strong but had no effect on fecundity. Thus, the cost of what appeared to be the same immune response – melanization of a bead – depended on the type of bead that stimulated the immune system. Such differences might help to explain variation of immune efficacy against different parasites in natural populations.
Swift laboratory thermal evolution of wing shape (but not size) inDrosophila subobscuraand its relationship with chromosomal inversion polymorphism
Authors: Santos M. , Iriarte P.F. , Céspedes W. , Balanyà J. , Fontdevila A. , Serra L.
Published: June 2004

Latitudinal clinal variation in wing size and shape has evolved in North American populations of Drosophila subobscura within about 20 years since colonization. While the size cline is consistent to that found in original European populations (and globally in other Drosophila species), different parts of the wing have evolved on the two continents. This clearly suggests that ‘chance and necessity’ are simultaneously playing their roles in the process of adaptation. We report here rapid and consistent thermal evolution of wing shape (but not size) that apparently is at odds with that suggestion. Three replicated populations of D. subobscura derived from an outbred stock at Puerto Montt (Chile) were kept at each of three temperatures (13, 18 and 22 °C) for 1 year and have diverged for 27 generations at most. We used the methods of geometric morphometrics to study wing shape variation in both females and males from the thermal stocks, and rates of genetic divergence for wing shape were found to be as fast or even faster than those previously estimated for wing size on a continental scale. These shape changes did not follow a neat linear trend with temperature, and are associated with localized shifts of particular landmarks with some differences between sexes. Wing shape variables were found to differ in response to male genetic constitution for polymorphic chromosomal inversions, which strongly suggests that changes in gene arrangement frequencies as a response to temperature underlie the correlated changes in wing shape because of gene-inversion linkage disequilibria. In fact, we also suggest that the shape cline in North America likely predated the size cline and is consistent with the quite different evolutionary rates between inversion and size clines. These findings cast strong doubts on the supposed ‘unpredictability’ of the geographical cline for wing traits in D. subobscura North American colonizing populations.
Extinction of the acoustic startle response in moths endemic to a bat-free habitat
Authors: Fullard J. H. , Ratcliffe J. M. , Soutar A. R.
Published: June 2004

Most moths use ears solely to detect the echolocation calls of hunting, insectivorous bats and evoke evasive flight manoeuvres. This singularity of purpose predicts that this sensoribehavioural network will regress if the selective force that originally maintained it is removed. We tested this with noctuid moths from the islands of Tahiti and Moorea, sites where bats have never existed and where an earlier study demonstrated that the ears of endemic species resemble those of adventives although partially reduced in sensitivity. To determine if these moths still express the anti-bat defensive behaviour of acoustic startle response (ASR) we compared the nocturnal flight times of six endemic to six adventive species in the presence and absence of artificial bat echolocation sounds. Whereas all of the adventive species reduced their flight times when exposed to ultrasound, only one of the six endemic species did so. These differences were significant when tested using a phylogenetically based pairwise comparison and when comparing effect sizes. We conclude that the absence of bats in this habitat has caused the neural circuitry that normally controls the ASR behaviour in bat-exposed moths to become decoupled from the functionally vestigial ears of endemic Tahitian moths.
Sources of stochasticity in models of sex allocation in spatially structured populations
Authors: Proulx S. R.
Published: June 2004

There are many ways to include stochastic effects in models of sex allocation evolution. These include variability in the number of mating partners and fecundity in a rich literature that goes back 20 years. The effects of variance in the fecundity and number of mating partners have typically been considered separately from the stochastic effects of mortality. However, I show that these processes produce mathematically equivalent models with subtly different biological details. These scenarios differ in the way that information becomes available to individuals because the parents often have information on mating partners while they are making sex allocation decisions, but must make these decisions before brood mortality takes place. This makes it possible to test which mechanism, stochastic mortality or variation in mating partners, is responsible for observed sex ratios. Alternatively, asymmetric variance between sexual functions can cause skewed sex allocation, even in the absence of local mate competition. This allows the evolution of either female- or male-biased sex ratios depending on which sexual function is more variable.
Experimental reduction of codon bias in the Drosophila alcohol dehydrogenase gene results in decreased ethanol tolerance of adult flies
Authors: Carlini David B.
Published: June 2004

The ethanol tolerance of adult transgenic flies of Drosophila containing between zero and ten unpreferred synonymous mutations that reduced codon bias in the alcohol dehydrogenase (Adh) gene was assayed. As the amino acid sequences of the ADH protein were identical in the four genotypes assayed, differences in ethanol tolerance were due to differences in the abundance of ADH protein, presumably driven by the effects of codon bias on translational efficiency. The ethanol tolerance of genotypes decreased with the number of unpreferred synonymous mutations, and a positive correlation between ADH protein abundance and ethanol tolerance was observed. This work confirms that the fitness effects of unpreferred synonymous mutations that reduce codon bias in a highly expressed gene are experimentally measurable in Drosophila melanogaster.
Evolution of eusociality and the soldier caste in termites: a validation of the intrinsic benefit hypothesis
Authors: Roux E. A. , Korb J.
Published: June 2004

In termites the evolution of reproductive altruism is not based on a particularly high relatedness between nestmates. For the evolution and maintenance of the ancestral sterile soldier caste, the benefits generated by the soldiers’ presence must compensate the loss of the soldiers’ reproductive potential. To study the impact of soldiers on colony's fitness, we manipulated the proportion of soldiers to nonsoldiers in colonies of the dry-wood termite Cryptotermes secundus.‘Soldier-less’ colonies were obtained by removing soldiers and inhibiting their development with an extract of soldier heads. The colonies were set up for 1 year in experimental nests in the field. ‘Soldier-less’ colonies produced fewer soldiers. The reduction of soldiers neither affected colony survival nor helper growth, but fewer dispersing sexuals were produced in ‘soldier-less’ than in control colonies. This confirms what was only supposed so far, that in termites soldiers are maintained for their intrinsic benefit to cost ratio.
Relatedness affects competitive performance of a parasitic plant (Cuscuta europaea) in multiple infections
Authors: Puustinen S. , Koskela T. , Mutikainen P.
Published: June 2004

Theoretical models predict that parasite relatedness affects the outcome of competition between parasites, and the evolution of parasite virulence. We examined whether parasite relatedness affects competition between parasitic plants (Cuscuta europaea) that share common host plants (Urtica dioica). We infected hosts with two parasitic plants that were either half-siblings or nonrelated. Relative size asymmetry between the competing parasites was significantly higher in the nonrelated infections compared to infections with siblings. This higher asymmetry was caused by the fact that the performance of some parasite genotypes decreased and that of others increased when grown in multiple infections with nonrelated parasites. This result agrees with the predictions of theories on the evolution of parasite virulence: to enhance parasite transmission, selection may favour reduced competition with genetically related parasites in hosts infected by several genotypes. However, in contrast to the most common predictions, nonrelated infections were not more virulent than the sibling infections.
‘Anti-bee’ and ‘pro-bird’ changes during the evolution of hummingbird pollination in Penstemon flowers
Authors: Castellanos M. C. , Wilson P. , Thomson J. D.
Published: June 2004

Floral phenotypes may be as much the result of selection for avoidance of some animal visitors as selection for improving the interaction with better pollinators. When specializing on hummingbird-pollination, Penstemon flowers may have evolved to improve the morphological fit between bird and flower, or to exclude less-efficient bees, or both. We hypothesized how such selection might work on four floral characters that affect the mechanics of pollen transfer: anther/stigma exsertion, presence of a lower corolla lip, width of the corolla tube, and angle of flower inclination. We surgically modified bee-pollinated P. strictus flowers changing one trait at a time to make them resemble hummingbird-pollinated P. barbatus flowers, and measured pollen transfer by bumblebees and hummingbirds. Results suggest that, apart from ‘pro-bird’ adaptations, specific ‘anti-bee’ adaptations have been important in shaping hummingbird-flowers. Moreover, some trait changes may have been selected for only if changing in concert with other traits.
High dose refuge strategies and genetically modified crops – reply to Tabashnik et al.
Authors: Vacher C. , Bourguet D. , Rousset F. , Chevillon C. , Hochberg M. E.
Published: June 2004

Cultivating non-toxic conventional crops (refuges) in the proximity to transgenic crops that produce Bacillus thuringienesis (Bt) toxins is widely recommended to delay pest adaptation to these toxins. Using a spatially structured model of resistance evolution, Vacher and co-workers (Vacher, C., Bourguet, D., Rousset, F., Chevillon, C. & Hochberg, M.E. 2003. J. Evol. Biol.16: 378–387.) show that the percentage of refuge fields required for the sustainable control of pests can be reduced through intermediate levels of refuge field aggregation and by lowering the toxin dose produced by Bt plants. Tabashnik, B.E., Gould, F. & Carrière, Y. (2004 J. Evol. Biol doi: 10.1111/j1420–9101.2004.00695.x) call into question the results of Vacher et al. (2003) concerning the effect of toxin dose. They argue that these results arise from invalid assumptions about larval concentration–mortality responses for the insect considered, the cotton pest Heliothis virescens. We show here that the models presented by Vacher et al. (2003) and Tabashnik et al. (2004) both show inaccuracies in their definitions of genotypic fitness. The level of dominance estimated by Tabashnik et al. (2004) from larval mortality rates data is irrelevant to resistance evolution, and the fitness cost of resistance evolution, and the fitness cost of resistance is inaccurately integrated into their framework. Neverthless, the comments of Tabashnik et al. (2004) are very helpful in elucidating the definitions of genotypic fitness used in Vacher et al. (2003) and in pointing out the essential factors in predicting the evolution of insect resistance to Bt transgenic crops, namely, accurate estimations of the fitness cost of resistance, of the dominance level of this cost, and of the variations in the dominance level of the advantage conferred by the resistance with Bt toxin dose.
The interaction between reproductive lifespan and protandry in seasonal breeders
Authors: Morbey Y. E. , Abrams P. A.
Published: June 2004

The timing and duration of reproductive activities are highly variable both at the individual and population level. Understanding how this variation evolved by natural selection is fundamental to understanding many important aspects of an organism's life history, ecology and behaviour. Here, we combine game theoretic principles governing reproductive timing and the evolutionary theory of senescence to study the interaction between protandry (the earlier arrival or emergence of males to breeding areas than females) and senescence in seasonal breeders. Our general model applies to males who are seeking to mate as frequently as possible over a relatively short period, and so is relevant to many organisms including annual insects and semelparous vertebrates. The model predicts that protandry and maximum reproductive lifespans should increase in environments characterized by high survival and by a low competitive cost of maintaining the somatic machinery necessary for survival. In relatively short seasons under these same conditions, seasonal declines in the reproductive lifespans of males of equivalent quality will be evolutionarily stable. However, over a broad range of potential values for daily survival and maintenance cost, reproductive lifespan is expected to be relatively short and constant throughout a large fraction of the season. We applied the model to sockeye (or kokanee) salmon Oncorhynchus nerka and show that pronounced seasonal declines in reproductive lifespan, a distinctive feature of semelparous Oncorhynchus spp., is likely part of a male mating strategy to maximize mating opportunities.
Hybridization and regional sex ratios in Nemophila menziesii
Authors: Barr C. M.
Published: June 2004

I tested whether a region of high female frequencies in the gynodioecious plant, Nemophila menziesii, may be due to hybridization between regionally distributed populations with different corolla colours. I crossed plants in the greenhouse from populations with different corolla colours and found that hybrid crosses yielded higher frequencies of females than within-colour crosses. In the field, I found that populations with high female frequencies had intermediate mean corolla colours and higher variance in corolla colour, two traits suggesting hybridization. Nemophila menziesii has nuclear–cytoplasmic sex inheritance, thus if populations with different corolla colours are fixed for different male-sterile cytoplasms and matching nuclear restorer alleles, hybridization between populations with different corolla colour should yield high frequencies of females. Two populations that are all hermaphroditic in the field segregated females in hybrid crosses suggesting that field populations may contain sex ratio distorters but appear undistorted, a prediction of genomic conflict theory.
Interspecific aggression and character displacement in the damselfly Calopteryx splendens
Authors: Tynkkynen K. , Rantala M. J. , Suhonen J.
Published: June 2004

Problems in species recognition are thought to affect the evolution of secondary sexual characters mainly through avoidance of maladaptive hybridization. Another, but much less studied avenue for the evolution of sexual characters due to species recognition problems is through interspecific aggression. In the damselfly, Calopteryx splendens, males have pigmented wing spots as a sexual character. Large-spotted males resemble males of another species, Calopteryx virgo, causing potential problems in species recognition. In this study, we investigate whether there is character displacement in wing spot size and whether interspecific aggression could cause this pattern. We found first that wing spot size of C. splendens in populations decreased with increasing relative abundance of C. virgo. Secondly, C. virgo males were more aggressive towards large- than small-spotted C. splendens males. Thirdly, in interspecific contests C. virgo males had better territory holding ability than C. splendens males. These results suggest that interspecific aggression may have caused character displacement in wing spot size of C. splendens, because the intensity of aggression towards large-spotted males is likely to increase with relative abundance of C. virgo males. Thus, interspecific aggression may be an evolutionarily significant force that is able to cause divergence in secondary sexual characters.
Testing for microevolution in body size in three blue tit populations
Authors: Charmantier A. , Kruuk L. E. B. , Blondel J. , Lambrechts M. M.
Published: June 2004

Quantifying the genetic variation and selection acting on phenotypes is a prerequisite for understanding microevolutionary processes. Surprisingly, long-term comparisons across conspecific populations exposed to different environments are still lacking, hampering evolutionary studies of population differentiation in natural conditions. Here, we present analyses of additive genetic variation and selection using two body-size traits in three blue tit (Parus caeruleus) populations from distinct habitats. Chick tarsus length and body mass at fledging showed substantial levels of genetic variation in the three populations. Estimated heritabilities of body mass increased with habitat quality. The poorer habitats showed weak positive selection on tarsus length, and strong positive selection on body mass, but there was no significant selection on either trait in the good habitat. However, there was no evidence of any microevolutionary response to selection in any population during the study periods. Potential explanations for this absence of a response to selection are discussed, including the effects of spatial heterogeneity associated with gene flow between habitats.
Ecological diversification in a group of Indomalayan pitvipers (Trimeresurus): convergence in taxonomically important traits has implications for species identification
Authors: Sanders K. L. , Malhotra A. , Thorpe R. S.
Published: June 2004

We analyse molecular and phenotypic evolution in a group of taxonomically problematic Indomalayan pitvipers, the Trimeresurus sumatranus group. Mitochondrial DNA sequencing provides a well-resolved phylogeny, with each species representing a distinct lineage. Multivariate morphological analysis reveals a high level of phenotypic differentiation, which is congruent between the sexes but does not reflect phylogenetic history. An adaptive explanation for the observed pattern of differentiation is supported by independent contrasts analysis, which shows significant correlations between current ecology and the characters that most account for the variation between taxa, including those that are presently used to identify the species. Reduced precipitation and altitude, and increased temperature, are correlated with higher numbers of scales on the head, body and tail. It is hypothesized that scale number plays an important role in heat and water exchange by influencing the area of exposed of interstitial skin, and that colour pattern variation reflects selection pressures involving camouflage and thermoregulation. Ecological convergence in traits used for classification is found to have important implications for species identification where taxa are distributed over varying environments.
Evolutionary genetics of dorsal wing colour in Colias butterflies
Authors: Ellers J. , Boggs C. L.
Published: June 2004

The evolution of butterfly wing colouration is strongly affected by its multiple functions and by the correlated evolution of wing colour elements. Both factors may prevent local adaptation to ecological conditions. We investigated one aspect of wing colouration, the degree of dorsal wing melanization, in the butterfly Colias philodice eriphyle across an elevational gradient and its correlation with another aspect of wing colouration, ventral wing melanization. Dorsal wing melanization increased with elevation and these differences persisted in a common environment. Full-sibling analysis revealed high heritability for males but only intermediate heritability for females. The correlation between ventral and dorsal melanization showed significant elevational and sex-specific differences. In males the two traits were highly correlated, whereas in females the strength of the correlation decreased with increasing elevation. We conclude that uncoupling of ventral and dorsal melanization has evolved in females but not in males and discuss possible mechanisms underlying uncoupling.
Sex-ratio distorter of Drosophila simulans reduces male productivity and sperm competition ability
Authors: Atlan A. , Joly D. , Capillon C. , Montchamp-Moreau C.
Published: June 2004

The aim of the present study was to determine whether the effects of sex-ratio segregation distorters on the fertility of male Drosophila simulans can explain the contrasting success of these X-linked meiotic drivers in different populations of the species. We compared the fertility of sex-ratio and wild-type males under different mating conditions. Both types were found to be equally fertile when mating was allowed, with two females per male, during the whole period of egg laying. By contrast sex-ratio males suffered a strong fertility disadvantage when they were offered multiple mates for a limited time, or in sperm competition conditions. In the latter case only, the toll on male fertility exceeded the segregation advantage of the distorters. These results indicate that sex-ratio distorters can either spread or disappear from populations, depending on the mating rate. Population density is therefore expected to play a major role in the evolution of sex-ratio distorters in this Drosophila species.
Constrained sex allocation in a parasitoid due to variation in male quality
Authors: Henter H. J.
Published: June 2004

The theory of constrained sex allocation posits that when a fraction of females in a haplodiploid population go unmated and thus produce only male offspring, mated females will evolve to lay a female-biased sex ratio. I examined evidence for constrained sex ratio evolution in the parasitic hymenopteran Uscana semifumipennis. Mated females in the laboratory produced more female-biased sex ratios than the sex ratio of adults hatching from field-collected eggs, consistent with constrained sex allocation theory. However, the male with whom a female mated affected her offspring sex ratio, even when sperm was successfully transferred, suggesting that constrained sex ratios can occur even in populations where all females succeed in mating. A positive relationship between sex ratio and fecundity indicates that females may become sperm-limited. Variation among males occurred even at low fecundity, however, suggesting that other factors may also be involved. Further, a quantitative genetic experiment found significant additive genetic variance in the population for the sex ratio of offspring produced by females. This has only rarely been demonstrated in a natural population of parasitoids, but is a necessary condition for sex ratio evolution. Finally, matings with larger males produced more female-biased offspring sex-ratios, suggesting positive selection on male size. Because the great majority of parasitic hymenoptera are monandrous, the finding of natural variation among males in their capacity to fertilize offspring, even after mating successfully, suggests that females may often be constrained in the sex allocation by inadequate number or quality of sperm transferred.
Clinical manifestations of sarcoid liver disease
Authors: BLICH MIRY , EDOUTE YEOUDA
Published: June 2004

Sarcoidosis is a systemic granulomatous disease of unknown etiology that involves many organs and has different clinical manifestation. We reviewed the clinical manifestations of sarcoid liver disease. Liver involvement in sarcoidosis can be serious and life‐threatening, independent of its lung and other organ involvement.
Clinical implications of quantification of mesorectal tumor invasion by endoscopic ultrasound: All T3 rectal cancers are not equal
Authors: HAREWOOD GAVIN C , KUMAR K SHIVA , CLAIN JONATHAN E , LEVY MICHAEL J , NELSON HEIDI
Published: June 2004

Background: Depth of invasion beyond the muscularis propria (MP) by T3 rectal cancer can vary. The purpose of the present paper was to determine if depth of invasion beyond MP, as assessed by preoperative endoscopic ultrasound (EUS), can predict tumor recurrence in patients with T3 rectal tumors.

Methods: Patients with T3NxM0 rectal cancer, as determined by EUS, who underwent surgical resection (without preoperative neoadjuvant therapy) were reviewed by two blinded endosonographers. Tumors were classified as minimally invasive T3 (invasion ≤ 2 mm beyond MP by EUS) and advanced T3 disease (invasion > 2 mm).

Results: Forty‐two patients with T3 rectal tumors underwent surgical resection without receiving preoperative neoadjuvant therapy, of whom 14 had minimally invasive T3 and 28 had advanced T3 disease, as determined by preoperative EUS. Median follow up was 19 months. Tumor recurrence rates in minimally invasive and advanced T3 tumors were 14.3% and 39.3%, respectively,P = 0.02 (log–rank test). Adjusting for nodal status and postoperative adjuvant therapy administration, Cox proportional hazards model demonstrated advanced T3 disease (by EUS) to predict tumor recurrence, hazard ratio, 2.28 (95% confidence interval: 1.17–5.81),P = 0.01.

Conclusions: All T3 rectal tumors are not equal, with minimally invasive disease carrying a more favorable prognosis. By discriminating minimally invasive from advanced T3 disease, preoperative EUS provides important prognostic information. Further subclassification of T3 tumors, based on preoperative EUS staging, should be considered to enhance selection of patients for neoadjuvant therapy.

© 2004 Blackwell Publishing Asia Pty Ltd
Immunohistochemical study of microvessel density, CD44 (standard form), p53 protein and c‐erbB2 in gallbladder carcinoma
Authors: KALEKOU HARIKLEIA , MILIARAS DIMOSTHENIS
Published: June 2004

Background:  The purpose of the present study was to investigate microvessel density (MVD), and the expression of CD44 adhesion molecule, p53 protein and c‐erbB2 in gallbladder carcinoma, and their relation to histological grade and tumor invasiveness.

Methods:  Immunohistochemical staining with antibodies against factor VIIIRAg, CD44 standard form (CD44s), p53 protein and c‐erbB2 was performed on paraffin sections from 33 cases of gallbladder carcinoma.

Results:  Significant increase of MVD with increasing depth of invasion (P < 0.02) was observed. No association of MVD with histological differentiation, CD44s, p53 and c‐erbB2 protein expression was found. The expression of p53 protein was significantly higher in deeply invasive tumors (P = 0.028) and in moderately and poorly differentiated carcinomas (P < 0.05). The CD44s expression was higher in well‐differentiated carcinomas (P < 0.05). c‐erbB2 expression was found in 30.4% of tumors studied, but did not relate to any other parameters.

Conclusion:  Microvessel density and p53 protein expression increase progressively with increasing tumor  invasiveness  in  gallbladder  carcinomas.  Microvessel  density,  p53  protein,  CD44s,  and  perhaps c‐erbB2 expression may be implicated in gallbladder carcinoma evolution.
Efficacy of hepatitis B vaccination and interferon‐α‐2b combination therapy versus interferon‐α‐2b monotherapy in children with chronic hepatitis B
Authors: HELVACI MEHMET , KIZILGUNESLER ASLI , KASIRGA ERHUN , OZBAL EBRU , KUZU MUGE , SOZEN GULBEN
Published: June 2004

Background:  Although interferon (IFN) has been approved in the treatment of chronic hepatitis B in children, it is effective only in 30–40% of patients. In some studies it has been suggested that therapeutic use of anti‐hepatitis B virus (HBV) vaccine may be beneficial in patients with chronic hepatitis B. The aim of the present study was to compare the efficacy of hepatitis B vaccination and IFN‐α‐2b in combination and IFN‐α‐2b monotherapy in children with chronic hepatitis B.

Methods:  Fifty treatment‐naive children with chronic hepatitis B infection were randomly assigned to receive either 5 million units/m2 recombinant IFN‐α‐2b subcutaneously three times per week for 9 months, and pre‐S2/S vaccine at the beginning and 4 and 24 weeks after initiation of IFN therapy (n = 25) or recombinant IFN‐α‐2b (5 million units/m2 subcutaneously thrice weekly) alone for 9 months (n = 25). Children were followed for at least 6 months after the end of therapy.

Results:  There was no statistically significant difference in the mean alanine aminotransferase levels, histologic activity index and fibrosis scores between combination and IFN monotherapy groups at the end of the therapy and end of the follow‐up period. When combination and monotherapy groups were compared, the mean HBV‐DNA values were significantly reduced in combination group at the end of the therapy (P = 0.004), but no statistically significant difference was found at the end of the follow up. Sustained HBeAg seroconversion with clearance of HBV‐DNA was obtained in 13 of 25 children (52%) treated with combination therapy, and in eight of 25 patients (32%) treated with IFN monotherapy (P = 0.251).

Conclusion:  Although the difference was statistically insignificant, the sustained response rates were better in the combination therapy group than in the monotherapy group. The potential benefit of combining IFN and hepatitis B vaccine should be investigated in further studies with different regimens of combination therapy.

© 2004 Blackwell Publishing Asia Pty Ltd
Epidemiological features of irritable bowel syndrome in a Turkish urban society
Authors: CELEBI SELMAN , ACIK YASEMIN , DEVECI S ERHAN , BAHCECIOGLU I HALIL , AYAR AHMET , DEMIR ALI , DURUKAN POLAT
Published: June 2004

Background and Aim:  Irritable bowel syndrome (IBS) is a widespread functional bowel disorder and its prevalence in Western societies ranges from 3‐20%. The present study aimed to determine the prevalence of IBS in eastern Turkey, particularly in urban parts of Elazig where 250 000 people live.

Methods:  Of the 18 primary care centers, four were randomly selected for this study. All individuals (aged >17 years) living around the service area of these health centers were included. A total of 1900 subjects were randomly selected using the personal health records from the primary care centers. The total number of subjects that could be contacted was 1766. A questionnaire with multiple choice questions was applied to the subjects by medical students using the face‐to‐face technique. Prevalence of IBS and distribution of symptoms were evaluated by the Rome II criteria.

Results:  Of the 1766 subjects, 45.4% were male and 54.6% were female. Prevalence of IBS was 5% in males, 7.4% in females and 6.3% overall. The percentage of subjects with IBS in the 17–30 years age group was 26.2%; 52.3% in the 30–50 years age group and 21.6% in the above 50 years age group. Prevalence of IBS was highest (10.2%) in persons who were illiterate and lowest (3.0%) in university graduates. A positive correlation was determined between low economical status and prevalence of IBS (P < 0.05).

Conclusion:  Although IBS is widely present in Turkey, its prevalence is lower than that reported in Western communities. In the region where this study was carried out, IBS was more prevalent in females and in individuals with low educational and economical status.
Effect of Helicobacter pylori eradication on anti‐thrombotic dose aspirin‐induced gastroduodenal mucosal injury
Authors: GIRAL ADNAN , ÖZDOGAN OSMAN , ÇELIKEL ÇIGDEM A , TÖZÜN NURDAN , ULUSOY NEFISE B , KALAYCI CEM
Published: June 2004

Background:  Helicobacter pylori infection and non‐steroidal anti‐inflammatory drugs are two major causes of gastric injury but the effect of H. pylori eradication on the development of aspirin‐induced gastric mucosal injury is unclear. The aim of the present study was to investigate the effect of Helicobacter pylori eradication on gastroduodenal mucosal injury induced by antithrombotic doses of aspirin.

Methods:  Patients who had been planned to start on medium‐dose aspirin (300 mg) for any kind of indication were included in the study. All subjects underwent upper gastrointestinal endoscopy for determination of H. pylori status and Lanza score. The H. pylori‐positive patients were randomized to receive either aspirin + eradication (omeprazole 20 mg b.i.d. and amoxicillin 500 mg q.i.d. for 2 weeks) or aspirin + placebo eradication. Endoscopic reassessment was done 4 months after the onset of aspirin or when symptoms developed.

Results:  Thirty‐two patients (placebo group n = 16, H. pylori‐eradicated group n = 16) completed the study and Lanza scores of both groups were similar before treatment. Lanza scores significantly increased in the placebo group (0.69 ± 0.87 vs 2.25 ± 1.3, P < 0.0001) and did not change in the H. pylori‐eradicated group after aspirin treatment (0.43 ± 0.72 vs 0.75 ± 0.93, P > 0.05).

Conclusion:  Helicobacter pylori eradication may prevent medium‐dose aspirin‐induced gastroduodenal mucosal injury.
Ethnic and cultural determinants influence risk assessment for hepatitis C acquisition
Authors: DEV ANOUK , SUNDARARAJAN VIJAYA , SIEVERT WILLIAM
Published: June 2004

Background and Aim:  In the developed world hepatitis C virus (HCV) infection is predominantly associated with sharing contaminated equipment between injecting drug users (IDU). In developing countries inadequately sterilized medical equipment, transmission of infected blood and cultural practices have been implicated. Accurate risk factor assessment is essential for education targeted at risk reduction in culturally diverse populations.

Methods:  Ninety Australian‐born Caucasians and 72 South‐east Asian (SEA) HCV patients attending a Melbourne hospital liver clinic completed a questionnaire which assessed risk factor profile, perceived risk factors, knowledge of risk factors and methods to minimize transmission. Medical records were audited to identify doctor assessment of risk factors.

Results:  Risk factors in Caucasians were IDU, body piercing and tattooing (89%, 47% and 32%, respectively). Risk factors in SEA patients were injection therapy, dental therapy and surgery (89%, 70% and 38%, respectively). Most Caucasian patients (94%) correctly identified their mode of acquisition compared with 33% of SEA patients (P < 0.0001). Accurate risk factor documentation in medical records was more common in Caucasians (96 vs 32%; P < 0.0001). The majority of patients identified blood‐to‐blood and sexual/vertical transmission as important modes of acquisition. However, 33% of SEA patients believed transmission occurred through food, water and poor hygiene and 80% did not identify therapeutic injection or traditional medical practices as risk factors. Education provided to SEA patients did not address less well established routes of transmission.

Conclusions:  Ethnicity influences perception and knowledge of risk factors. Improved assessment of risk factors in high‐risk ethnic groups is needed. Education should be culturally appropriate and address the concerns of all populations with HCV.

© 2004 Blackwell Publishing Asia Pty Ltd
River, reservoir and lake sediment contamination by heavy metals downstream from urban areas of Switzerland
Authors: Wildi Walter , Dominik Janusz , Loizeau Jean‐Luc , Thomas Richard Linn , Favarger Pierre‐Yves , Haller Laurence , Perroud Antoine , Peytremann Christophe
Published: June 2004

This paper quantifies sediment contamination by heavy metals in four reservoirs and one lake located downstream from major urban areas in Switzerland. The waterbodies include the Wettingen Reservoir (located on the Limmat River downstream from Zürich), the Klingnau Reservoir (on the lower Aare River), the Wohlen Reservoir (downstream from Berne), the Verbois Reservoir (downstream from Geneva) and Vidy Bay (Lake Geneva, city of Lausanne). For all sediment cores and contaminants, a trend is observed from high contaminant values in the lower part of the cores, decreasing to lower concentrations in the upper part of the cores. However, for each site and each element, specific features are recognized. Applying the criteria of the Swiss ordinance on soil protection, all sediment cores must be classified as contaminated by one or more contaminants and at variable levels. From these data, it is concluded that: reservoirs and lakes located downstream from major urban centres in Switzerland have accumulated significant volumes of contaminated sediments in the past, representing the largest, but not the most intensely, contaminated sites on a national scale; the main environmental risk is remobilization of the contaminants and their return to the food chain, particularly by infiltration into the groundwater; and although the processes of remobilization are identified, the conditions of occurrence and the amplitude of the processes are still poorly known. Different options of reservoir and lake sediment management also are discussed and further research topics defined.
Anangu oral health: The status of the Indigenous population of the Anangu Pitjantjatjara lands
Authors: Endean Colin , Roberts‐Thomson Kaye , Wooley Simon
Published: June 2004

Objective:  To describe oral health in the A

n

angu Pitjantjatjaraku lands in South Australia and to compare with earlier surveys and national data.

Design:  Descriptive.

Setting:  Data were collected at the time of dental care service provision, according to World Health Organization protocols, at the request of the Nganampa Health Council on optical mark reader forms.

Participants:  There were 356 A

n

angu adults and 317 children surveyed.

Results:  The mean number of teeth affected by dental caries in the deciduous dentition in young children, aged 5–6 years, was double (mean 3.20) that of the overall Australian child population aged 5–6 years (mean 1.44). In contrast to the decline in deciduous caries in Australian children generally, A

n

angu children aged 5–9 years had a 42% increase in the mean number of teeth affected since 1987. Adults experienced low levels of dental caries, but severe periodontal disease was more prevalent among diabetics (79%) compared with‐non‐diabetics (13.8%). Tooth loss was found more frequently among adults with diabetes (mean 5.51) than non‐diabetics (mean 1.53).

Conclusions:  Oral health promotion strategies, in association with general health strategies, need to be developed to improve oral health in this remote Aboriginal population.

What this paper adds:  Recent studies have shown that oral health of Indigenous children is worsening, but there has been little documentation of the changing oral health status of Indigenous adults.

This study notes the deterioration of oral health in both children and adults since 1987/88. The relationship between glycaemic control, periodontal diseases and tooth loss in Indigenous adult populations needs to be further investigated.
Hemangiosarcoma of the third eyelid in a dog
Authors: Liapis I. K. , Genovese L.
Published: June 2004

A case of hemangiosarcoma of the third eyelid in a 7‐year‐old Caucasian Sheepdog is reported. A voluminous red mass protruding from the free edge of the third eyelid in the right eye was present. The mass and the free edge of the third eyelid were surgically excised. On histopathologic examination the tumor was seen to infiltrate the propria of the third eyelid and was composed of neoplastic mesenchymal cells forming irregular channels containing blood. These plump cells showed moderate anisocytosis and anisokaryosis with a low mitotic index. The surgical wound healed successfully and after 9 months there had been no recurrence. To the authors’ knowledge, this is the first hemangiosarcoma of the third eyelid reported in the dog.
A morphologic study of intravitreal membranes associated with intraocular hemorrhage in the dog
Authors: Zeiss Caroline J. , Dubielzig Richard R.
Published: June 2004

We aimed to characterize intravitreal membranes in dogs and determine, if possible, associated predisposing conditions. Five globes in which intravitreal membranes were identified were evaluated. These originated from four Labrador Retrievers or Labrador‐cross dogs and a Springer Spaniel. The ages of the dogs ranged from 4 to 11 years. Standard histology and immunohistochemical procedures for factor VIII‐related antigen, smooth muscle actin (SMA), vimentin and glial fibrillary acidic protein (GFAP) were performed. Intravitreal membranes varied from loosely to highly organized. The extent of organization corresponded with increasing immunoreactivity for vimentin and GFAP, indicating their predominantly glial origin. They were never immunopositive for smooth muscle actin, nor were they vascularized. In all cases, they were associated with intravitreal hemorrhage. Additional common findings included epiretinal membranes, retinal neovascularization, preiridal fibrovascular membranes and glaucoma. Intravitreal membranes may be a sequelae of intravitreal hemorrhage. This in turn, may arise from new vessels associated with epiretinal or preiridial membranes, or hemorrhage associated with optic disc cupping or retinal neovascularization. All of these phenomena may accompany glaucoma.