bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunohistochemical evidence for hepatic progenitor cells in liver diseases
Authors: Tan Jianyou , Hytiroglou Prodromos , Wieczorek Rosemary , Park Young NyuN. , Thung Swan N. , Arias Byron , Theise Neil D.
Published: March 2003

Abstract:  Background/Aim: Proliferative bile ductular reactions occur in a variety of liver diseases in humans. It is a matter of debate whether such reactions result from progenitor cell proliferation with biliary and hepatocytic differentiation, versus biliary metaplasia of damaged hepatocytes. We investigated bile ductular reactions in liver diseases, paying particular attention to the presence of cells with intermediate (hepatocytic/biliary) features (oval‐like cells).

Methods: Five specimens each were selected of submassive hepatic necrosis and cirrhosis due to hepatitis B, hepatitis C, autoimmune hepatitis, alcohol injury, primary biliary cirrhosis and primary sclerosing cholangitis. Immunohistochemical stains were performed for biliary markers (cytokeratins [CKs] 7 and 19), as well as hepatocytic markers (HepParl and alpha‐fetoprotein[AFP]) in sequential sections. The degree of staining of each cell type (biliary, hepatocytic, intermediate) was graded semiquantitatively.

Results: Hepatocytes always stained diffusely for HepParl, occasionally for CK7, and rarely for CK19. Biliary cells were always diffusely positive for CK7 and CK19, and rarely for HepParl. Intermediate cells were identified in all cases and showed widespread staining for both HepParl and CK7, and less commonly for CK19. AFP was not expressed in any cell type. The morphologic and immunohistochemical features of bile ductular reactions were similar in the different diseases.

Conclusions: Proliferating hepatic parenchymal cells with intermediate (hepatocytic/biliary) morphologic features and combined immunophenotype can be identified in a variety of acute and chronic liver diseases. The similarity of bile ductular reactions among chronic hepatitic, alcoholic and biliary diseases suggests that they result from proliferation of oval‐like progenitor cells.
Splenectomy ameliorates hepatic ischemia and reperfusion injury mediated by heme oxygenase‐1 induction in the rat
Authors: Ito Koji , Ozasa Hisashi , Yoneya Rika , Horikawa Saburo
Published: March 2003

Abstract: Background/Aims: Ischemia/reperfusion (I/R) induces severe organic injury. I/R injury seems to be mainly caused by oxidative stress. The aim of this study was to determine the role of the spleen in experimental hepatic I/R injury in the rat. Stress protein heme oxygenase (HO)‐1 plays a protective role against the oxidative injury. In normal state, HO‐1 is highly expressed in the spleen. Methods: Liver HO‐1 expression was assessed by Western blot before and after splenects. Liver injury was assessed by measurement of ALT and AST and by histopathology. Results: Although HO‐1 was not detected in normal liver, levels of HO‐1 protein gradually increased and peaked on 3 days after splenectomy. When splenectomy was performed 3 days prior to the hepatic (45‐min) ischemia followed by (2‐h) reperfusion, the levels of serum aspartate transaminase (AST) and alanine transaminase (ALT), as markers for hepatic injury, were improved compared to the rats with I/R alone. In addition, prior administration of zinc‐protoporphyrin IX, a specific inhibitor of HO, suppressed the protective effect of the splenectomy on the subsequent hepatic I/R injury. Histopathological examination also confirmed these results. Conclusions: Our findings suggest that the elevated HO‐1 levels by splenectomy play a protective role against hepatic I/R injury.
Inclusion of Vpr accessory gene in a plasmid vaccine cocktail markedly reduces Nef vaccine effectiveness in vivo resulting in CD4 cell loss and increased viral loads in rhesus macaques
Authors: Muthumani K. , Bagarazzi M. , Conway D. , Hwang D.S. , Ayyavoo V. , Zhang D. , Manson K. , Kim J. , Boyer J. , Weiner D.B.
Published: March 2003

Abstract: We compared the immunogenicity of plasmid vaccines containing multiple human immunodeficiency virus (HIV) antigens and found that covaccination with plasmids expressing HIV‐1 14 kDa vpr gene product profoundly reduces antigen‐specific CD8‐mediated cytotoxic T‐cell activity (CTL). Interestingly, Th1 type responses against codelivered antigens (pGag‐Pol, pNef, etc.) encoded by the plasmid vaccines were suppressed. This suggested that vpr might compromise CD8 T‐cell immunity in vivo during infection. A pilot primate vaccine study was designed to test the hypothesis to compare the following groups: unvaccinated controls, animals vaccinated without simean immunodeficiency virus (SIV)‐Nef antigen plasmid, and animals covaccinated with the identical plasmid antigen and a plasmid construct encoding SIV Vpr/Vpx. Animals were subsequently challenged intrarectally with pathogenic SIVmac251 after the final vaccination of a multiple immunization protocol. Control animals were all infected and exhibited high viral loads and rapid CD4+ T‐cell loss. In contrast, the Nef plasmid‐vaccinated animals were also infected but exhibited preservation of CD4+ T‐cells and a multilog reduction in viral load compared with controls. Animals covaccinated multiple times with the Nef vaccine and pVpr/Vpx plasmid suffered rapid and profound loss of CD4+ T‐cells. These results have important implications for the design of multicomponent and particle vaccines for HIV‐1 as well as for our understanding of HIV/SIV pathogenesis in vivo.
Spontaneous ovarian tumors in twelve baboons: a review of ovarian neoplasms in non‐human primates
Authors: Moore Charleen M. , Hubbard Gene B. , Leland M.Michelle , Dunn Betty G. , Best Robert G.
Published: March 2003

Abstract: Twelve spontaneous ovarian tumors were found in the Southwest Foundation for Biomedical Research baboon colony. These included four granulosa cell tumors, three teratomas, two endometrioid carcinomas, one seromucinous cystadenofibroma, a cystic papillary adenocarcinoma, and an ovarian carcinoma. Age was a pre‐disposing factor. With one exception, the tumors of surface epithelial‐ and sex cord‐stromal origin occurred in baboons over 17 years of age. The exceptional animal was 7 years of age when a malignant granulosa cell tumor with Sertoli cell differentiation was identified. The two endometrioid tumors, which were found in 17‐ and 30‐year‐old animals, were both associated with endometriosis. In contrast, the teratomas, which are tumors of germ cell origin, were found in younger animals, i.e. 17 years of age or younger. One case of an ovarian carcinoma with metastases was observed in a 6‐month‐old infant. Cases of spontaneous ovarian tumors from the literature are reviewed.
The relationship between FeO and Ti2O3 in ilmenite smelter slags
Authors: Pistorius P. Chris
Published: March 2003

Smelting is used to upgrade ilmenite (FeO.TiO2) to high‐titania slags which serve as feedstocks for TiO2 pigment manufacture. During smelting, partial reduction of FeO to liquid iron, and of TiO2 to Ti2O3, occurs. Lower FeO levels in the solidified slag correlate with higher Ti2O3. Since some pigment manufacturers limit the allowable Ti2O3 level in the slag, the origin of this relationship is of interest. Ilmenite smelter slag compositions from the literature were examined to test possible origins of the FeO–Ti2O3 relationship. Available equilibrium data indicated that the relationship does not follow equilibrium, nor is there likely to be a simple kinetic cause. It is concluded that a phase‐chemistry effect causes the relationship to follow closely that required by the stoichiometric M3O5 phase, the major component of solidified slag.
Effect of sulfur on the dissolution behaviour of graphite in Fe‐C‐S melts: A Monte Carlo simulation study
Authors: Sahajwalla V. , Khanna R.
Published: March 2003

We report a Monte Carlo computer simulation study on a solid graphite/Fe‐C‐S melt system at 1600°C. Atoms in graphite and melt were arranged on a graphitic hexagonal lattice with pair‐wise short‐range interactions. Optimum values of various interaction parameters were used for simulation. On coming in contact with hot melt, carbon atoms from graphite dissolve into iron melt with iron penetrating the graphite lattice. However, there is no evidence of sulfur penetrating the graphite block or remaining in the interfacial region. S atoms tend to move away from graphite, going deep into the iron melt. The presence of sulfur in the melt adversely affects interfacial kinetics, mass‐transfer and overall dissolution rate. These simulation results have been explained in terms of bond energy considerations.
Reproductive effort and blood parasites of breeding pied flycatchers: the need to control for interannual variation and initial health state
Authors: Sanz Juan José , Moreno Juan , Arriero Elena , Merino Santiago
Published: March 2003

The association between reproductive effort, as assessed by experimentally altered clutch size, and prevalence of blood parasite infections was studied during two breeding seasons in the pied flycatcher (Ficedula hypoleuca). Only in the first study year (1998), enlarged clutches resulted in more fledged young and birds presumably responded to the intended experimental increase in reproductive effort by increasing their provisioning rates. Only on this study year, female body mass was negatively affected by the clutch size manipulation. For both sexes, no significant effect of experimental treatment on the prevalence of blood parasite infections (Trypanosomaspp.,Haemoproteus balmorali) on day 13 after chick hatching was found in both study years. However, only in the first study year, when the intended increase in parental reproductive effort was achieved, we found a higher within female seasonal increase inTrypanosomaspp. prevalence for birds with enlarged clutches compared to those with control and reduced clutches. In this year, theTrypanosomaspp. prevalence was significantly higher than in the second study year. These results suggest that more than one year has to be covered, and that the knowledge of the premanipulative health status of parents can facilitate detection of the proposed trade‐off between reproductive effort and immunocompetence.
Interspecific and intraspecific interactions between salt marsh plants: integrating the effects of environmental factors and density on plant performance
Authors: Huckle Jonathan M. , Marrs Rob H. , Potter Jacqueline A.
Published: March 2003

There has been much debate about the role of plant interactions in the structure and function of vegetation communities. Here the results of a pot experiment with controlled environments are described where three environmental variables (nutrients, sediment type and waterlogging) were manipulated factorially to identify their effects on the growth and intensity of interactions occurring between Spartina anglica and Puccinellia maritima. The two species were grown in split‐plot planting treatments, representing intraspecific and interspecific addition series experiments, to determine individual and interactive effects of environmental factors and plant interactions on plant biomass. 

Above‐ground growth of both species involved interactions between the environmental and planting treatments, while below‐ground, environmental factors affected the biomass irrespective of planting treatments. It was suggested that this difference in growth response is evidence that in our experiment plant interactions between the two species occur primarily at the above‐ground level. 

The intensity of plant interactions varied in a number of ways. First, interactions between Spartina and Puccinellia were distinctly asymmetrical, Puccinellia exerting a competitive effect on Spartina, with no reciprocal effect, and with a facilitative effect of Spartina on Puccinellia in low nutrient conditions. Second, the interactions varied in intensity in different environmental conditions. Interspecific competitive effects of Puccinellia on Spartina were more intense in conditions favourable to growth of Puccinellia and reduced or non‐existent in environments with more abiotic stress. Third, intraspecific competition was found to be less intense for both species than interspecific interactions. Finally, the intensity of plant interactions involving both species was more intense above ground than below ground, with a disproportionate reduction in the intensity of interspecific competition below relative to above ground in treatments with less productive sediments and greater immersion. This is interpreted as reflecting a potential mechanism by which Spartina may be able to evade competitive neighbours.
Changes in population structure and reproduction during a 3‐yr population cycle of voles
Authors: Norrdahl Kai , Korpimäki Erkki
Published: March 2003

Cyclic changes in population growth rate are caused by changes in survival and/or reproductive rate. To find out whether cyclic changes in reproduction are an important part of the mechanism causing cyclic fluctuations in small mammal populations, we studied changes in the population structure and reproduction of field voles (Microtus agrestis), sibling voles (M. rossiaemeridionalis), bank voles (Clethrionomys glareolus), and common shrews (Sorex araneus) in western Finland during 1984–1992, in an area with 3‐yr vole cycles. We also modelled the population growth of voles using parameter values from this study. The animals studied were collected by snap trapping in April, May, June, August, September, and, during 1986–1990, also in October. We found several phase‐related differences in the population structure (age structure, sex ratio, proportion of mature individuals) and reproduction (litter size, length of the breeding season) of voles. In non‐cyclic common shrews, the only significant phase‐related difference was a lower proportion of overwintered individuals in the increase phase. According to the analyses and the vole model, phase‐related changes in litter size had only a minor impact on population growth rate. The same was true for winter breeding in the increase phase. The length and intensity of the summer breeding season had an effect on yearly population growth but this impact was relatively weak compared to the effect of cyclic changes in survival. The population increase rates of Microtus were delayed dependent on density (8–12‐month time lag). Our results indicate that cyclic changes in reproduction are not an important part of the mechanism driving cyclic fluctuations in vole populations. Low survival of young individuals appeared to play an important role in the shift from the peak to the decline phase in late summer and early autumn.
Compensation: an alternative method for analyzing diversity‐productivity experiments
Authors: Adler Peter B. , Bradford John B.
Published: March 2003

Although recent experimental results demonstrate a positive effect of diversity on primary productivity, the interpretation of these experiments has been controversial, creating a need for new methods of analysis. The methods developed in response to this need all use the production of individual species grown in monocultures to calculate the expected production of each species mixture, then analyze departures from these expectations as a function of species richness. We propose an alternative method that treats the same assembly experiments as species removals, and calculates the expected production of each mixture based on the production of individual species when grown together in the full community (the experimental mixture containing all species in the pool). Using the observed production of the full community, and the observed and expected productions of less diverse mixtures, we calculate an index of compensation that measures the degree of functional recovery following species loss. To explore whether losses of dominant versus subordinate species have different ecosystem effects, we suggest a multiple regression approach that tests the influence of both species richness and expected production on compensation. If compensation varies with species richness or expected production consistently in many experimental systems, then we may be able to predict the ecosystem effect of different types of extinctions.  While existing monoculture approaches more directly test hypotheses about complementary resource use, the compensation approach offers two advantages: 1) it is more appropriate for testing how extinctions will affect ecosystem function, and 2) it may provide an important link between assembly experiments in artificial communities and removal experiments in natural systems.
Size‐dependent resource allocation among vegetative propagules and male and female functions in the forest herb Laportea bulbifera
Authors: Sato Toshihiko
Published: March 2003

Reproductive resource investment among vegetative propagules and male and female sexual function and their size‐dependence were investigated in a perennial forest herb, Laportea bulbifera. A theoretical model based on fitness gain curves predicts that optimal investments in three reproductive modes will increase with plant size if fitness returns in all three modes increase but become saturated with investment. In a field population, large plants of L. bulbifera produced both male and female inflorescences with propagules, while small plants produced only vegetative propagules. Biomass of propagules, male inflorescences, and infructescences with achenes were all positively correlated with plant size. The increase in investment with plant size was larger for propagule production than for sexual reproduction. The relationship between propagule biomass and plant size was constant irrespective of year, while the relationship between the biomass of sexual reproductive organs and plant size differed between two successive years. Annual change of individual sex expression was investigated for 25 transplanted plants. Although each plant changed its sex expression variously among male, female and bisexual from year to year, 23 out of 25 plants produced both male and female inflorescences in at least one year. The number of viable (germinated and survived) offspring from seeds was not significantly different from the number from propagules. The production cost of a propagule was higher than that of a seed. Resource allocation theory does not seem to be applicable to size‐dependent resource allocation, especially the allocation between seeds and propagules in this species.
Size‐dependent competitive ability in a deposit‐feeding amphipod, Monoporeia affinis
Authors: Aljetlawi Albashir A. , Leonardsson Kjell
Published: March 2003

We investigated the competitive ability in terms of maintenance resource density, C0, in relation to body size, of a deposit feeder Monoporeia affinis (Lindström) (Amphipoda). Growth curves were obtained from nine‐day single size‐class experiments with several food densities, consisting of fresh phytoplankton. The functional response and the size‐dependence of attack rate (clearance rate) and handling time were estimated using a dynamic growth model including ingestion and energetic costs. The energetic costs were obtained from treatments without food. C0 was solved from the growth model by setting growth to zero. The best description of growth was found using a Holling type II functional response. The attack rate was independent of M. affinis body size, while handling time decreased, and C0 increased with body size.

 To investigate the occurrence of intercohort interference and its influence on C0, we used the parameter estimates to predict the growth in mixed size‐classes experiments. These experiments were similar to the single size‐class experiments except for the addition of two size‐classes of M. affinis. The observed growth was lower than predicted for all size‐classes. Incorporation of an interference term to the functional response in the growth model improved its fit to the observed data. This indicated that both interference and exploitation competition occurred. The interference increased C0 for the smallest sizes, and reduced its size‐dependence. C0 increased most for the largest individuals, but most likely for reasons other than interference. According to predictions by Persson et al. (1998) concerning population dynamic properties, our results indicate that the unstable dynamics commonly found for this species are due to higher competitive ability of juveniles rather than of maturing sub‐adults.
Density‐dependent habitat selection: evaluating isoleg theory with a Lotka‐Volterra model
Authors: Guthrie Carla G. , Moorhead Daryl L.
Published: March 2003

Contemporary models of density‐dependent habitat selection generally focus on long‐term evolutionary consequences of intraspecific or interspecific competition and/or patterns of resource use in patchy environments. A primary goal of such studies often is to elucidate evolutionary stable strategies based on steady‐state dynamics of population growth. In contrast, we developed a simulation model to explore short‐term movements of interspecific competitors among fine‐grained habitats of differing attributes, as might result from field manipulations of habitat quality or population densities. In this model, habitat quality is expressed in terms of mean individual fitness, represented by average per capita growth rate calculated according to the Lotka‐Volterra equations describing interspecific competition. This model provides a mechanism for quantifying the effects of habitat quality, patterns of resource use and competition on distributions of individuals. Results demonstrate the heuristic value of this model in corroborating predictions derived from the ideal free distribution and isodar theory, and in generating isolegs to test the predictions of isoleg theory. Results indicate that small changes in model parameters have substantial impacts on patterns of habitat use and co‐occurrence between species. The model identifies a variety of conditions under which isolegs for a given type of community organization deviate from predictions of contemporary isoleg theory, potentially expanding the universe of possible interspecific behaviors underlying the development of evolutionary stable strategies.
Interactive effects of diversity, nutrients and elevated CO2 on experimental plant communities
Authors: He Jin‐Sheng , Bazzaz Fakhri A. , Schmid Bernhard
Published: March 2003

The effects of species richness and elevated CO2 on community productivity under altered nutrient levels were studied in experimental herbaceous communities composed of species from the Midwestern United States annual community, which consists of three functional groups C3, C4 and N‐fixers. Aboveground and belowground biomass were measured at flowering stage and at the end of the experiment when fruits of most plants were ripe. At the low nutrient level, species richness did not have a significant effect on community productivity. However, at the high nutrient level, the community biomass decreased with decreasing species richness at both ambient and elevated CO2 in the first harvest, and at elevated CO2 in the second harvest. At low nutrient level, CO2 slightly increased community biomass at medium and high species richness. At high nutrient level, CO2 significantly increased community biomass in all species‐richness treatments in the first harvest, but a significant response was observed only in the high richness treatment in the second harvest. At the functional group level, biomass of C3 responded positively to CO2, and C4 responded very negatively to CO2. The N‐fixers responded positively to CO2 at low and medium species richness, but negatively at high species richness, showing a CO2×richness interaction. CO2 increased species evenness in the communities, depending on nutrient level. Species varied in the responses of light‐saturated net photosynthesis (Pmax) to elevated CO2, even within functional groups. Our findings suggest that (1) the relationship between productivity and species diversity was dependent on nutrient levels. (2) Species diversity enhances responses of communities to elevated CO2. (3) Harvest time can affect the results of diversity‐productivity experiments. (4) Responses of C3, C4, and N‐fixers to elevated CO2 in communities did not follow the prediction based on functional groups or plants grown individually, rather it depended on species richness.
Antipredator reaction norms for life history traits in Daphnia pulex: dependence on temperature and food
Authors: Weetman D. , Atkinson D.
Published: March 2003

Synergistic effects between temperature and food level on the vulnerability of Daphnia life histories to predation have previously received little attention, despite their potential significance for summer population dynamics. In this investigation, most traits in the early life history of Daphnia pulex altered in response to increasing concentrations of fish kairomone. Although there was some variation attributable to experimental temperature and food treatments, traits exhibited reaction norms which suggested at least some degree of kairomone dose‐dependence. Temperature, food level and their interaction affected the mean values of every trait examined and in some cases also influenced the antipredator response via a three‐way interaction with fish kairomone. The insertion of an extra juvenile instar resulted in later maturation at a larger size for most females raised under conditions of low temperature and low food, but this response was largely suppressed in the presence of fish kairomone. Earlier maturation due to deletion of an instar was observed most frequently under high food and temperature conditions with fish kairomone present, suggesting an effect of kairomone on the size threshold for reproductive development. Principal components analysis was used to produce an index reflecting the net potential vulnerability to fish predation of the suite of life history traits. Vulnerability generally declined with increasing kairomone level as a result of the apparently adaptive alterations in most life history traits. Raised temperature and food level also generally reduced potential vulnerability, but a highly significant interaction between these factors was also found. Potentially important implications of these results for optimal vertical migration and summer population dynamics are discussed.
The role of conservation in expanding biodiversity research
Authors: Srivastava Diane S.
Published: March 2003

It has been suggested that current reductions in global biodiversity may impair the functioning of ecosystems. This biodiversity‐ecosystem function (BD‐EF) hypothesis represents a new avenue of ecological research originating from conservation concerns. However, the subsequent evolution of BD‐EF research has reflected academic concerns more than conservation priorities. I suggest three questions for BD‐EF research, which would benefit both ecological theory and conservation. (1) Is biodiversity the main driver of ecosystem function? Several experiments show that biodiversity loss is a minor link between habitat change and ecosystem function. (2) How will extinction patterns change BD‐EF relationships? Biased extinctions may have additional impacts on ecosystem function, which can be deduced by comparison with random‐loss models. (3) Will conserving regional biodiversity conserve local ecosystem function? The answer to this question may differ between saturated and unsaturated communities, and may depend on whether the magnitude or stability of ecosystem function is measured.
Density dependence in foraging habitat preference of eastern grey kangaroos
Authors: Ramp Daniel , Coulson Graeme
Published: March 2003

For a free‐ranging forager, the suitability of a patch is dependent on population density, resource supply, resource quality, and the costs of foraging or dispersal. We quantified differences among three foraging habitats and compared this variation to temporal patterns of habitat preference by free‐ranging eastern grey kangaroos, Macropus giganteus. We investigated selection on a fine‐grained spatial scale, and asked whether habitat preference is constrained by density‐dependent mechanisms. Variation in the quantity and quality of resources among habitats was greatest during spring, when biomass and quality were highest, and differences among habitats were most pronounced. However, consistent and discernable differences among habitats were not obtained, indicating that the system fluctuated around an equilibrium state. Using isodar regressions to examine the consumer‐density relationships among habitats, open‐woodland habitat was favoured over the two open‐forest habitats for foraging. Seasonal isodars indicated that density dependence regulated preference between the three foraging habitats during autumn, spring and summer, but not during winter, when variability in resources among habitats was lowest.
Species richness, environmental fluctuations, and temporal change in total community biomass
Authors: Petchey Owen L. , Casey Tim , Jiang Lin , McPhearson P. Timon , Price Jennifer
Published: March 2003

Theory and empirical results suggest that high biodiversity should often cause lower temporal variability in aggregate community properties such as total community biomass. We assembled microbial communities containing 2 to 8 species of competitors in aquatic microcosms and found that the temporal change in total community biomass was positively but insignificantly associated with diversity in a constant temperature environment. There was no evidence of any trend in variable temperature environments. Three non‐exclusive mechanisms might explain the lack of a net stabilising effect of species richness on temporal change. (1) A direct destabilising effect of diversity on population level variances caused some populations to vary more when embedded in more diverse communities. (2) Similar responses of the different species to environmental variability might have limited any insurance effect of increased species richness. (3) Large differences in the population level variability of different species (i.e., unevenness) could weaken the relation between species richness and community level stability. These three mechanisms may outweigh the stabilising effects of increases in total community biomass with diversity, statistical averaging, and slightly more negative covariance in more diverse communities. Our experiment and analyses advocate for further experimental investigations of diversity‐variability relations.
From inducible defences to population dynamics: modelling refuge use and life history changes in Daphnia
Authors: Vos Matthijs , Flik Ben J. G. , Vijverberg Jacobus , Ringelberg Joop , Mooij Wolf M.
Published: March 2003

We investigated the relative importance of a behavioural defence (refuge use through diel vertical migration) and a life history change (a reduced size at first reproduction) that are used by daphnids to decrease the risk of predation by visually hunting fish. We used an individual based model of a Daphnia population in a stratified lake to quantify the effects of these inducible defences on Daphnia predation‐mortality and the resulting Daphnia population dynamics. Our analysis shows that diel vertical migration (DVM) confers a much stronger protection against fish predation than a reduced size at first reproduction (SFR). DVM allows daphnids to withstand a higher predation pressure in the epilimnion and it decelerates a Daphnia population decline more strongly than a reduced SFR. DVM effectively reduces the (P/B) flow of carbon from daphnids to fish.

 Many theoretical studies have only considered the fitness benefits of DVM above ‘staying up’ in the epilimnion of a lake. Our results suggest that ‘staying down’ in the hypolimnion would confer an even stronger fitness benefit to Daphnia than DVM at times of peak predation risk. Daphnids that remain in the hypolimnion avoid the predation suffered by migrating daphnids around dusk and dawn. Staying down could prevent a Daphnia population decline, while DVM and a reduced SFR can only decelerate the decrease of Daphnia population densities under heavy fish predation. Staying down at high concentrations of fish infochemicals has in fact been observed within a variety of Daphnia clones and species, both in the laboratory and in stratified lakes.
Overexpression of p53 and bcl‐2 proteins and the presence of HPV infection are independent events in head and neck cancer
Authors: Badaracco Gianna , Venuti Aldo , Bartolazzi Armando , Morello Roberto , Marzetti Francesco , Marcante Maria Luisa
Published: March 2003

Abstract: The expression of p53 and bcl‐2 proteins by immunohistochemistry and the identification of human papillomavirus (HPV) infection by a non‐isotopic polymerase chain reaction (PCR)‐based method were investigated in 30 patients with head and neck cancer. Ten cases were HPV‐positive (33%), mostly as double or multiple infections by high‐ or intermediate‐risk types. Twenty‐one patients were p53‐positive (70%), 9/10 with HPV‐positive tumours and 12/20 with HPV‐negative tumours; this difference was not statistically significant. Only four cases were bcl‐2‐positive, irrespective of the presence of either HPV or p53. No correlation was found between these biological factors and tumour stage, differentiation grade, and alcohol or tobacco use. Our findings indicate that p53 is involved in the majority of cases, bcl‐2 is rare, and high‐risk HPV could play a key role, especially in tumours of tongue and tonsil. In conclusion p53 and bcl‐2 protein expression and the presence of HPV infection are independent events in these malignancies.
Fluid phase endocytosis in oral epithelia: variation with site and effect of cancer
Authors: Hall W. , Ogden G. R. , Saleh A. H. , Hopwood D. , E. Ross P.
Published: March 2003

Abstract: The structure of the oral mucosa has been extensively studied but its cell physiology has been less well characterised. This study aimed to show the range in variation in fluid phase endocytic capability in biopsies from different oral sites. Oral epithelial cells were obtained from both biopsies and single‐cell suspensions obtained by brushing the oral cavity. Biopsies in organ culture and single cells in suspension were incubated with fluorescent microspheres of 0.02, 0.1 or 1.0 μm diameter. Endocytosis of fluorescent microspheres was quantitated by flow cytometry and visualised by confocal microscopy. Epithelial cells from all oral sites that were sampled internalised 0.02 μm and 0.1 μm but not 1.0 μm microspheres, with no significant differences observed between oral regions. Single cells from non‐cancer patients endocytosed significantly more 0.02 μm microspheres than cells removed from patients with oral cancer. This model may be used to study integrated oral cell function both in health and disease.
Fas expression and Fas monoclonal antibody‐induced apoptosis in a human squamous cell carcinoma cell line, SCC‐25
Authors: Seta Chihiro , Fujita Michi , Muraki Yukoh , Fukuda Jinichi , Kobayashi Shigeru , Haneji Tatsuji
Published: March 2003

Abstract: Fas antigen is a cell surface protein that mediates apoptosis via signal transduction from the plasma membrane. Using reverse transcriptase–polymerase chain reaction (RT‐PCR), messenger RNA for Fas antigen was detected in the human oral squamous cell carcinoma cell line, SCC‐25. In serum‐free medium, a monoclonal anti‐Fas antibody (CH‐11) induced Fas antigen expression in SCC‐25 cells, as determined by immunocytochemistry and Western blotting, using an anti‐Fas polyclonal antibody (Fas D) as primary antibody. Fas antigen was localized to the cytoplasm and the cell membrane. The molecular weight of the protein recognized by Western blot analysis was 35,000, consistent with the value reported for the Fas antigen. The CH‐11 antibody did not induce Fas antigen expression in serum‐containing medium. To determine whether CH‐11 could induce apoptosis in oral squamous cell carcinoma, we examined its effects on the survival of cultured SCC‐25 cells. Anti‐Fas monoclonal antibody in serum‐free medium induced cytotoxicity in SCC‐25 cells in a time‐dependent manner up to 8 h, as determined by phase‐contrast microscopy and WST‐1 assay. Marked nuclear condensation and fragmentation of chromatin were observed in the CH‐11‐treated cells using Hoechst 33342 staining. This anti‐Fas monoclonal antibody also induced DNA ladder formation in SCC‐25 cells in a time‐dependent manner. The present results indicate that the anti‐Fas monoclonal antibody (CH‐11) may mediate apoptosis by binding to the Fas antigen expressed in SCC‐25 cells.
Enhancing effects of fibroblast growth factor on the proliferation of salivary gland carcinoma cells and salivary gland carcinogenesis
Authors: Yura Yoshiaki , Yoshioka Yukio , Yamamoto Sin , Kusaka Jun , Bando Takashi , Yoshida Hideo , Sato Mitsunobu
Published: March 2003

Abstract: The proliferation of mouse submandibular gland carcinoma YT‐12 cells was stimulated by endothelial cell growth factor (ECGF)/bovine brain‐derived acidic fibroblast growth factor (aFGF) and recombinant human aFGF. To determine whether aFGF was capable of modifying salivary gland carcinogenesis, the effect of brain‐derived aFGF was examined in vivo. Mice in Groups 1 and 2 were injected with 9,10‐dimethyl‐1,2‐benzanthracene (DMBA) into the left submandibular gland, and then Group 1 mice received bovine brain‐derived aFGF and Group 2 mice received vehicle subcutaneously for 10 weeks. Group 3 and 4 mice received either bovine brain‐derived aFGF or vehicle only. Sixteen weeks after the start of the experiment, the incidence of submandibular gland carcinomas in Group 1 was significantly greater than that in Group 2. Immunohistochemical study indicated that ducts in the normal submandibular glands and carcinomas showed positive staining with anti‐aFGF antibody. Immunoblot and reverse transcriptase‐polymerase chain reaction (RT‐PCR) analysis revealed the expression of aFGF in these tissues. FGF receptor (FGFR)‐1 and FGFR‐4 were detectable in the mouse submandibular glands and carcinomas. These findings suggest that bovine brain‐derived aFGF stimulates the proliferation of submandibular gland carcinoma cells and promotes mouse submandibular gland carcinogenesis.
Adenomatoid odontogenic tumour: immunohistochemical demonstration of transferrin, ferritin and alpha ‐ one ‐ antitrypsin
Authors: Takahashi H. , Fujita S. , Shibata Y. , Yamaguchi A.
Published: March 2003

Abstract: Three cases of adenomatoid odontogenic tumour (AOT) were examined by morphological and immunohistochemical methods, to define the nature of tumour cells and to determine the correlation between the occurrence of extracellular eosinophilic amorphous material and epithelial tumour cells. The epithelial tumour cell components observed in this study were divided into three cell types (cell type I: small compact cells in a solid nodule and pseudoglandular cells in a duct‐like structure; cell type II: peripheral elongated cells and spindle‐shaped cells in a cribriform pattern; and cell type III: metaplastic squamous cells). The mesenchymal components consisted of eosinophilic amorphous material and calcified material. Immunohistochemically, the type I cells reacted positively with antibodies to transferrin, ferritin and alpha‐one‐antitrypsin (α1‐AT), whereas the type II cells constantly indicated intense expression only for transferrin and α1‐AT. All types of epithelial tumour cells reacted negatively with lactoferrin, alpha‐one‐antichymotrypsin, S‐100 protein, S‐100α subunit and S‐100β subunit. Moreover, the eosinophilic amorphous material and calcified material examined were positive for the antibody against α1‐AT. These materials expressed immunophenotypes similar to those of the epithelial tumour cells, except for metaplastic squamous cells. The present study showed that iron‐binding proteins and proteinase inhibitor might be related to the pathogenesis of AOT. Furthermore, we indicated that the formation of eosinophilic amorphous material was associated with type I and type II cells.
Natural immunity in recurrent aphthous ulceration
Authors: Sistig S. , Cekic‐Arambasin A. , Rabatic S. , Vucicevic‐Boras V. , Kleinheinz J. , Piffko J.
Published: March 2003

Abstract: In the present study we investigated immunophenotypes of peripheral blood lymphocytes, natural killer (NK) cell activity as well as spontaneous migration, ingestion, digestion and antibody‐dependent cell‐mediated cytotoxicity (ADCC) as effector functions of polymorphonuclear neutrophil granulocytes (PMNs) in 51 patients with acute stage recurrent aphthous ulceration (RAU), during remission, and 47 age‐matched healthy individuals. Statistically significant lower B‐lymphocyte (CD19) values were found between patients with acute RAU, and those during the remission period (P<0.001), when compared with those of the controls. Total T‐lymphocyte (CD3) percentages were lower in patients with RAU, and also during the remission period, when compared with the controls (P<0.001). The percentages of CD4 lymphocytes were significantly lower in patients with RAU in comparison with those of the controls (P<0.001). T‐suppressor cells (CD8) were unchanged in all three groups of participants. Significantly lower spontaneous migration and ingestion values were found in patients with acute RAU, when compared with those of the controls, and during the remission period (P<0.001). Digestion values differed insignificantly between the patients with acute RAU and during the remission period. During the remission period, digestion values were significantly elevated when compared with those of the controls (P<0.05). ADCC values were lower during the remission period (P<0.001), when compared with the values during acute RAU and with those of the controls. Significantly depressed NK activity (P<0.001) was observed in patients with acute RAU, when compared with that of the controls. During the remission period, values of NK activity were also lower (P<0.001) when compared with those of the controls. These results suggest either a specific or nonspecific immunological disorder in patients with RAU.
Immunohistochemical localization of fibroblast growth factors FGF‐1 and FGF‐2, and receptors FGFR2 and FGFR3 in the epithelium of human odontogenic cysts and tumors
Authors: So Felicia , Daley Tom D. , Jackson Linda , Wysocki George P.
Published: March 2003

Abstract: Acidic (FGF‐1) and basic (FGF‐2) fibroblast growth factors are members of a family of growth factors that function in growth, differentiation and regeneration of a variety of tissues. Their presence in human odontogenic cysts and tumors has not been previously investigated. This study was designed to detect immunohistochemically the presence of these factors and two fibroblast growth factor receptors (FGFR2 and FGFR3) in a cross section of odontogenic cysts and tumors, to determine if they may be involved in the differentiation of odontogenic epithelium or, more specifically, in the development of particular cysts or tumors. Archival formalin‐fixed paraffin‐embedded tissues were used. With some exceptions, FGF‐2 and the receptor FGFR2, were found in the cytoplasm and occasionally in the nuclei of cells of odontogenic epithelium, while FGF‐1 and the receptor FGFR3, were absent or only focally or weakly detected, using standard immunohistochemical techniques. The data are similar to those published for normal murine odontogenesis, suggesting that these factors are associated with odontogenic differentiation rather than pathogenesis. The presence of significant nuclear staining in odontogenic epithelium associated with embryonic mesenchyme in ameloblastic fibromas and ameloblastic fibro‐odontomas suggests that FGF‐2 may be involved in directing nuclear activity at the histodifferentiation stage of odontogenesis.
Loss of heterozygosity: a potential tool in management of oral premalignant lesions?
Authors: Zhang L. , Rosin M. P.
Published: March 2003

Abstract: Oral leukoplakia, a heterogeneous group of lesions, demonstrates a varying degree of risk for cancer progression. Histology (presence and degree of dysplasia), the current gold standard for assessing this risk, is reasonably effective in judging the malignant risk of high‐grade pre‐invasive lesions. It is, however, a poor predictor for lesions without dysplasia, or with minimal dysplasia, as only a few of these lesions will progress to cancer. This poses an enormous dilemma for clinicians as to whether these lesions should be aggressively treated or not. Recent studies show that loss of specific chromosomal regions (loss of heterozygosity, LOH) that contain known or presumptive tumor suppressor genes is an early predictor of subsequent progression of oral premalignant lesions. Incorporation of LOH findings into staging of oral premalignancy could improve our ability to identify and manage high‐risk premalignant lesions, particularly those with relatively benign histology but high‐risk genetic changes (high‐risk LOH pattern).
Expression of CD44 standard and variant isoforms in parotid gland and parotid gland tumours
Authors: Franchi Alessandro , Moroni Michele , Paglierani Milena , Santucci Marco
Published: March 2003

Abstract: In this study, we investigated the distribution of the standard form of the CD44 (CD44s) cell adhesion molecule and of its v3 and v6 isoforms in samples of foetal and adult parotid gland tissue, in comparison with samples of parotid gland adenomas and carcinoma ex pleomorphic adenoma. Foetal parotid gland showed CD44s and CD44v3 expression in the peripheral small primordial ducts and acini, while CD44v6 was only focally expressed. Adult parotid gland tissue showed a similar distribution of CD44s and variants, with a predominant expression in acinar structures and a weaker expression at duct level. In parotid gland adenomas, a diffuse and intense expression of CD44s and variants 3 and 6 was observed only in pleomorphic adenomas, while expression of CD44s was prevalent in Warthin’s tumour, myoepithelioma and oncocytoma. The malignant areas of carcinoma ex pleomorphic adenoma showed a markedly decreased expression of CD44v3 and CD44v6 in comparison with the adjacent pleomorphic adenoma component. In conclusion, the prevalent expression of CD44s and variants in pleomorphic adenoma in comparison with other adenomas may be related to the abundant extracellular matrix production present in these tumours, while loss of CD44v3 and CD44v6 associated with the onset of carcinoma ex pleomorphic adenoma could promote stromal invasion, eventually contributing to the development of distant metastases.