bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling as a teaching learning process for understanding materials: A case study in primary education
Authors: Acher Andrés , Arcà María , Sanmartí Neus 
Published: January 2007

AbstractModeling is being used in teaching learning science in a number of ways. It will be considered here as a process whereby children of primary school age exercise their capacity of organizing recognizable and manageable forms during their understanding of complex phenomenologies. The aim of this work is to characterize this process in relation to the modeling of properties of and changes in materials. The data are discussed by establishing relationships between the modeling process with three different aspects: the specialized scientific knowledge, the physical manipulation of phenomena, and the interaction among those participating in the class. The results show how 7–8‐year‐old students generate a modeling process that leads them to explain the behavior of different materials by using a “model of parts” created ad hoc. This model, built up from some kind of a discrete vision of the material, proves to be coherent for children of this age and evolves by relating the visible continuum with an imagined discontinuum. © 2007 Wiley Periodicals, Inc. Sci Ed 91:398–418, 2007
Global transcriptional profiling of Candida albicans cwt1 null mutant
Authors: Moreno I. , Castillo L. , Sentandreu R. , Valentin E. 
Published: January 2007

AbstractCaCwt1p is a Candida albicans putative transcriptional factor homologue to Rds2p in Saccharomyces cerevisiae. The lack of this protein in S. cerevisiae leads to a pleiotropic resistance to drugs and defects in cell wall architecture that are also detectable in C. albicans. It is also known that CaCwt1p is mainly expressed in the stationary growth phase of this fungus. In order to elucidate the role of CWT1, transcriptome analysis of the mutant strain was performed in exponential and stationary growth phases. A total of 460 genes were found to be up‐ or downregulated in the mutant strain growing exponentially, and 666 genes presented a misregulation when cwt1 cells reached the stationary phase. Under both conditions, 6% of the genes were related to cell wall architecture. An important set of genes involved in protein translation and ribosome biogenesis presented altered expression levels in cwt1 in both exponential and stationary growing cells. In addition, genes encoding for glycolytic enzymes and glycerol formation were found to be differentially regulated throughout cell growth. Finally, the expression of other transcriptional factors was modified in cwt1. This fact could indicate that the pleiotropic phenotype presented by the cwt1 null mutant is not only due to its absence, but also to the modified expression of other transcriptional factors. RSAT software was used to predict theoretical DNA binding motifs for this transcriptional factor. Surprisingly, the DNA sequences AGGGCT and/or AGCCCT could act as a direct promoting binding site for Cwt1p. These sequences have been reported to be related to the STRE box. Copyright © 2007 John Wiley & Sons, Ltd.
Relating body size to the role of aquatic subsidies for the riparian spider Nephila clavata
Authors: Akamatsu Fumikazu , Toda Hideshige , Okino Tokio 
Published: January 2007

AbstractWe examined the relationship between body size of the riparian spider Nephila clavata and the contribution of allochthonous (aquatic insects) and autochthonous (terrestrial insects) sources to its diet using stable isotope analysis. During the study period from July to September, the body size of the females increased remarkably (about 60‐fold) but that of males remained small. The biomass of both aquatic and terrestrial insects trapped on the spider webs increased with spider size, with the biomass of the former ranging between 30 and 70% of that of the terrestrial insects. The average relative contribution of aquatic insects to the diet of the spiders, calculated from δ13C values, was 40–50% in spiders in the early juvenile and juvenile stages, 35% in adult males and 4% in adult females. There was a significant negative relationship between the relative contribution of aquatic insects and body size of the female spiders. We conclude that aquatic insects might be an important seasonal dietary subsidy for small spiders and that these allochthonous subsidies may facilitate the growth of riparian spiders, which may in turn enable the spiders to feed on larger prey.
Effect of reduced levels of the LDL receptor of Ehrlich ascites tumor cells on cholesterol uptake and cell proliferation: A coculture study with baby hamster kidney cells
Authors: Haeffner E.W. , Wittmann U. , Kiesewetter L. , Zimmermann H.P. , Stöhr M. , Spiess E. 
Published: January 2007

AbstractWe have introduced a heterologous coculture model between Ehrlich ascites tumor (EAT) and baby hamster kidney cells (PtK2), and we have studied the influence of PtK2 cells and their newly synthesized cholesterol on uptake and tumor cell proliferation. PtK2 cells produce about five times more cholesterol as compared to EAT cells, and they support tumor cell growth in coculture experiments. This growth stimulation is reduced by 80% when EAT cells are cultured in PtK2 cell‐derived medium in the presence of a monoclonal anti‐low‐density lipoprotein receptor (anti‐LDLr) antibody. Freshly synthesized cholesterol by PtK2 cells is taken up by EAT cells in a time‐dependent manner amounting to a threefold increase after 24 h. Alternatively, cholesterol transfer to EAT cells is decreased between 28% and 35%, when PtK2 cell cholesterol synthesis is inhibited in the presence of mevinolin, the specific inhibitor of the hydroxy‐3‐methyl‐glutaryl‐coenzyme A (HMG‐CoA) reductase. Furthermore, lower levels of EAT cell LDL receptor induced by antisense technology reduces cholesterol uptake and cell proliferation. These data demonstrate a metabolic interaction between normal and tumor cells mediated via the exchange of cholesterol, an important membrane constituent.
Analysis of the monovalent ion fluxes in U937 cells under the balanced ion distribution: Recognition of ion transporters responsible for changes in cell ion and water balance during apoptosis
Authors: Vereninov A.A. , Goryachaya T.S. , Moshkov A.V. , Vassilieva I.O. , Yurinskaya V.E. , Lang F. , Rubashkin A.A. 
Published: January 2007

AbstractUnidirectional 22Na, Li+ and Rb+ fluxes and net fluxes of Na+ and K+ were measured in U937 human leukemic cells before and after induction of apoptosis by staurosporine (1 μM, 4 h) to answer the question which ion transporter(s) are responsible for changes in cell ion and water balance at apoptosis. The original version of the mathematical model of cell ion and water balance was used for analysis of the unidirectional ion fluxes under the balanced distribution of major monovalent ions across the cell membrane. The values of all major components of the Na+ and K+ efflux and influx, i.e. fluxes via the Na+,K+‐ATPase pump, Na+ channels, K+ channels, Na/Na exchanger and Na‐Cl symport were determined. It is concluded that apoptotic cell shrinkage and changes in Na+ and K+ fluxes typical of apoptosis in U937 cells induced by staurosporine are caused by a complex decrease in the pump activity, Na‐Cl symport and integral Na+ channel permeability.
Mechanosensitive channel activity and F‐actin organization in cholesterol‐depleted human leukaemia cells
Authors: Morachevskaya Elena , Sudarikova Anastasiya , Negulyaev Yuri 
Published: January 2007

AbstractThis study focuses on the functional role of cellular cholesterol in the regulation of mechanosensitive cation channels activated by stretch in human leukaemia K562 cells. The patch‐clamp method was employed to examine the effect of methyl‐β‐cyclodextrin (MβCD), a synthetic cholesterol‐sequestering agent, on stretch‐activated single currents. We found that cholesterol‐depleting treatment with MβCD resulted in a suppression of the activity of mechanosensitive channels without a change in the unitary conductance. The probability that the channel was open significantly decreased after treatment with MβCD. Fluorescent microscopy revealed F‐actin reorganization, possibly involving actin assembly, after incubation of the cells with MβCD. We suggest that suppression of mechanosensitive channel activation in cholesterol‐depleted leukaemia cells is due to F‐actin rearrangement, presumably induced by lipid raft destruction. Our observations are consistent with the notion that stretch‐activated cation channels in eukaryotic cells are regulated by the membrane—cytoskeleton complex rather than by tension developed purely in the lipid bilayer.
Nuclear differentiation for mating types in the ciliate Dileptus anser: A hypothesis
Authors: Yudin A.L. , Uspenskaya Z.I. 
Published: January 2007

AbstractWe have obtained the first data on inheritance and genetic determination of mating types (MTs) in the lower ciliate Dileptus anser (= D. margaritifer). Observation of MT instability in young, just matured exconjugant clones obtained from some (not all) crosses appears to be the key finding in our study. In a clone of this kind, the states of maturity and immaturity (or adolescence) often alternate and/or one MT changes to another, sometimes repeatedly, during the period of several weeks after the clone's maturation. On occasion, all three MTs found in this species can be expressed consecutively. All cells of the culture are synchronously involved in such changes of their sexual state — no spontaneous selfing (intraclonal conjugation) was ever observed in such cultures. These observations suggest that the mat locus in dilepti is a compound integral one; it is inherited as a whole and can specify expression of any one of possible MTs (much as it occurs in Tetrahymena thermophila). Some other mechanisms, supposedly epigenetic ones among them, control what MT will be expressed in a given exconjugant clone in particular. Steady functioning of these mechanisms provides stable, unambiguous differentiation of the compound mat locus to one and only one MT and subsequent Mendelian behavior of the character over sexual generations. If, for some still unknown reasons the control of such differentiation is disturbed, MT expressed in a given exconjugant clone becomes unstable and its Mendelian behavior can be violated.
Alcohol and young people
Authors: Ritson Bruce 
Published: January 2007

In most countries, the past decade has seen an increase in alcohol consumption which has been particularly evident among young people. This increase has been most marked for girls. These changes have brought about an attendant rise in alcohol related problems amongst adolescents.The paper examines the place of alcohol education in fostering moderate drinking and reviews research on the development of drinking habits. Finally it considers the task of professionals working with adolescents in responding to alcohol problems once they are recognized.
How much do young offenders need social work?
Authors: Kerslake Andrew 
Published: January 2007

The current orthodoxy in social work with young offenders centres on the twin themes of justice and systems management. The first beseeches social work to use mechanisms, such as the 1982 Criminal Justice Act, as a means of improving the juvenile court process. The second seeks to provide a clear alternative to custody by redefining Intermediate Treatment as a strategy aimed primarily at “heavy end” offenders.The recent news that the numbers of those receiving Youth Custody has risen sharply since the implementation of the above Act, only serves to amplify the importance of the debate about what kind of social work young offenders should receive. The current implication for both the courts and social work practice is that justice is not being done and diversion not being achieved.However, should social work respond by concentrating the vast majority of its endeavours in one particular area, then it would clearly have major implications both for practice and for the allocation of resources. It would therefore have an effect on the kind of social work young offenders might receive and hence how much such a service may be required.
Participation of the Fas and Fas ligand systems in apoptosis during atrophy of the rat submandibular glands
Authors: Takahashi Shigeru , Gobe Glenda C. , Yoshimura Yoshitaka , Kohgo Takao , Yamamoto Tsuneyuki , Wakita Minoru 
Published: January 2007

SummaryMost acinar cells and some duct cells undergo apoptosis during atrophy of the submandibular gland. The present study was designed to elucidate whether Fas and its receptor ligand (FasL) are involved during apoptotic atrophy of the gland. The excretory duct of the right submandibular gland of rats was doubly ligated with metal clips from 1 to 14 days for induction of gland atrophy. Control rats were untreated. Fas and FasL expression in the atrophied submandibular gland was detected using immunohistochemistry (IHC) and Western immunoblot. Expression of activated caspase 8 and activated caspase 3 was also detected with IHC. Fas‐positive acinar and duct cells and FasL‐positive duct cells increased in the atrophic glands at 3 and 5 days after duct ligation when apoptotic cells were commonly observed. Thereafter, Fas‐ and FasL‐positive cells declined in number. Patterns of expression of Fas and FasL using Western immunoblots concurred with the IHC results. Activated caspase 8‐positive cells were present at every time interval but peaked at 3 and 5 days following duct ligation. The cells showing immunoreaction for activated caspase 3 first appeared on day 3, with the peak in apoptosis, after which they decreased. The results indicate that the Fas/FasL systems likely play an important role in apoptotic pathways during atrophy of the submandibular gland.
Experimental cutaneous Bacillus anthracis infections in hairless HRS/J mice
Authors: Bischof Timothy S. , Hahn Beth L. , Sohnle Peter G. 
Published: January 2007

SummaryPrevious studies of experimental Bacillus anthracis cutaneous infections in mice have implicated hair follicles as a likely entry site. Hairless HRS/J mice were used to investigate this possibility because of their non‐functional hair follicles that lack penetrating hair shafts. These mice also have diminished macrophage function, increased susceptibility to Listeria, and enhanced neutrophil responses. HRS/J and Balb/c mice were found to be resistant to epicutaneous inoculation with Bacillus anthracis (Sterne) spores onto abraded skin when compared with DBA/2 mice or leucopenic C57BL/6 mice. The HRS/J mice also resisted spore injections that bypassed hair follicles. Haired HRS/J heterozygote mice demonstrated similar reduced susceptibility to B. anthracis spores. Hairless HRS/J mice that were made leucopenic did become susceptible to the epicutaneous spore inoculations. Histologically, the hairless and haired HRS/J mice showed markedly reduced numbers of organisms in hair follicles and the interfollicular dermis when compared even with the resistant Balb/c mice; inflammatory cell infiltrates in the superficial dermis were increased in the HRS/J mice compared with more sensitive strains. Therefore, resistance in the HRS/J mice was apparent at the initial site of epicutaneous inoculation and seemed related to an accumulation of dermal neutrophils rather than to a lack of functional hair follicles.
Determinants of parasitoid abundance and diversity in woodland habitats
Authors: FRASER SALLY E. M. , DYTHAM CALVIN , MAYHEW PETER J. 
Published: January 2007

Summary

Insect parasitoids comprise a large fraction of terrestrial biodiversity. Because of this diversity, species‐level conservation of most parasitoid species is impractical and habitat conservation must substitute. However, habitat indicators of parasitoid abundance and diversity are poorly known.
To identify such habitat indicators, parasitoid wasps in four ichneumonid subfamilies were sampled in the field herb layer of 15 woodlands in the Vale of York, UK, using Malaise traps. The catch was related to vegetation characteristics.
A total of 1543 individuals in 60 species was recorded, representing 36% of UK species in the taxa sampled. Parasitoids tended to be more abundant and species rich in woodlands with a high broadleaf content and tree species richness. This pattern was observed in the ichneumonid subfamilies Pimplinae, Poemeniinae and Diacritinae.
However, the ichneumonid subfamily Diplazontinae was found to vary in abundance and richness within rather than between woodlands and showed no association with measured habitat variables.
Reserve selection analyses indicated that coniferous woodlands, and woodlands with a low abundance and richness of parasitoids, none the less can contribute to maximizing parasitoid diversity at the landscape scale.
Synthesis and applications. At the individual woodland scale, broadleaved woodlands with high tree species richness appear best for conserving parasitoid abundance and diversity. At a landscape scale however, a variety of woodland habitat types can maximize diversity of all parasitoid taxa. We hypothesize that the degree of association between parasitoid abundance and diversity, and characteristics of the vegetation within habitats will decrease with an increase in the number of trophic links that separate them.
Differential anti‐chemokine activity of Amblyomma variegatum adult ticks during blood‐feeding
Authors: VANČOVÁ I. , SLOVÁK M. , HAJNICKÁ V. , LABUDA M. , ŠIMO L. , PETERKOVÁ K. , HAILS R. S. , NUTTALL P. A. 
Published: January 2007

SUMMARY Ticks secrete a cocktail of immunomodulatory molecules in their saliva during blood‐feeding, including chemokine‐binding factors that help control the activity of host immunocompetent cells. Here we demonstrate differential dynamics of anti IL‐8 (CXCL8), MCP‐1 (CCL2), MIP‐1 (CCL3), RANTES (CCL5) and eotaxin (CCL11) activities in salivary gland extracts of adult Amblyomma variegatum. Unfed male and female ticks showed activity against all the chemokines except CCL5; anti‐CCL11 activity was particularly high. However, during feeding the dynamics of anti‐chemokine activity differed significantly between males and females, and varied between chemokines. In males, anti‐chemokine activities increased, whereas in females they declined or increased slightly as feeding progressed. The exception was anti‐CCL11 activity, which declined and then increased in both males and females. Comparison of salivary gland equivalents of individual ticks prepared at various feeding intervals revealed some differences that were most pronounced between individual females fed for 8 days. These observations reflect the feeding behaviour of male and female A. variegatum. They support the concept of ‘mate guarding’, in which males help their mates to engorge by controlling their host's immune response, and the possibility that ticks benefit from feeding together by exploiting molecular individuality.
The virulence of phytopathogenic fungi associated with the bark beetles Tomicus piniperda and Orthotomicus erosus in Tunisia
Authors: Ben Jamaa M. L. , Lieutier F. , Yart A. , Jerraya A. , Khouja M. L. 
Published: January 2007

SummaryPhytopathogenic fungi associated with the bark beetles Tomicus piniperda and Orthotomicus erosus were isolated in various pine forests of Tunisia. Tomicus piniperda and its galleries yielded Leptographium wingfieldii, Ophiostoma minus, and Ophiostoma ips. Ophiostoma minus was the most frequent species associated with T. piniperda, in both the attacking and the emerging beetles. It was collected from most investigated forests, whereas O. ips and L. wingfieldii were obtained only from forests located in Central and Northern Tunisia. Frequencies of association with T. piniperda were always low, reaching 11.1% only once, for O. ips. Ophiostoma ips was the only blue stain fungus associated with O. erosus and its galleries. It was found in all the localities, but at a low and variable frequency, exceeding 15% very rarely. The virulence of 16 fungal isolates was tested by single inoculations into Pinus halepensis (Aleppo pine) at two localities. Differences were detected among species; L. wingfieldii was the most virulent and O. minus the least virulent species in terms of phloem reaction zone formation and fungal growth in the phloem. In a separate experiment, mass inoculations (400 and 800 inoculations per m2 of bole on 1‐m high belts) were performed with two isolates of L. wingfieldii on Aleppo pine and on Pinus brutia (Brutia pine). Three months later, measurements of sapwood status (% of conductive transversal section) and of its specific hydraulic conductivity, as well as of the phloem reaction zone lengths, did not show any isolate or density effect. At these experimental sites, Brutia pines appeared significantly more susceptible than Aleppo pines.
Double‐bundle reconstruction of the anterior cruciate ligament
Authors: Nau Thomas , Spotswood Matthew 
Published: January 2007

Abstract Injuries of the anterior cruciate ligament often present in rural practices and rural regional hospitals. Surgical reconstruction is the treatment of choice in the young and active patient. Better biomechanical understanding has led to a further improvement of the surgical technique. The double‐bundle reconstruction, which aims to address both functional bundles of the anterior cruciate ligament, represents the latest development in this field. In this review article the basic biomechanical principles as well as a new surgical technique are presented for practitioners in rural practice and rural regional hospitals.
Use of clinical placements as a means of recruiting health care students to underserviced areas in Southeastern Ontario: Part 1 – Student perspectives
Authors: MacRae Michelle , Van Diepen Kelly , Paterson Margo 
Published: January 2007

AbstractObjective:  This two‐part study examines the present gap between financial and educational incentives required and the recruitment strategies used to draw health science students to underserviced areas in Southeastern Ontario. Part 1 explores the impact of offering travel stipends, rent‐free accommodation and interprofessional educational opportunities to health science students on their willingness to participate in clinical placements in underserviced areas. Design:  Mixed‐method two‐part study using a self‐administered questionnaire. Setting:  Canadian university campus. Participants:  Four hundred and sixty‐eight senior level medical, nursing, occupational therapy, physical therapy and X‐ray technology students from a Canadian university and affiliated professional school. Main outcome measures:  The influence of currently established incentives on student willingness to complete a clinical placement in designated underserviced communities in Southeastern Ontario. Results:  Based on a 75% response rate, the results demonstrate that, in general, students agree that they are more willing to complete a clinical placement in an underserviced community if provided travel stipends (75%), rent‐free housing (92%) and interprofessional educational opportunities (65%). Students also identified 15 additional factors influencing willingness. Conclusions:  Students are more willing to complete clinical placements in underserviced communities if provided incentives. The findings of this study support an interprofessional clinical education and recruitment enhancement program in Southeastern Ontario.