bluuebunny/crossref_metadata_2025 huggingface dataset:
Responsiveness to General Education Instruction as the First Gate to Learning Disabilities Identification
Authors: Speece Deborah L. , Case Lisa Pericola , Molloy Dawn Eddy
Published: December 2004

Most definitions of learning disabilities (LD) include a qualification that adequate general education instruction was received and the child with LD did not benefit. Rarely is this tenet assessed in either practice or research before a diagnosis is made. We review three studies that investigated children's responsiveness to general education reading instruction as an indicator of need for more intensive interventions. Adequacy of instruction was quantified by children's level and rate of progress, compared to classmates, as measured by curriculum‐based measures of oral reading fluency. We found that the response‐to‐instruction model tested was valid in that (1) children who differ from their peers on level and slope of performance (dual discrepancy) have more severe academic and behavioral problems than children who have IQ‐achievement discrepancies or low achievement; (2) children who demonstrate persistent nonresponsiveness over three years differ from other at‐risk children on reading, reading‐related, and behavioral measures; and (3) at‐risk children who participated in specially designed general education interventions had better outcomes than at‐risk children who did not participate. We conducted additional analyses to assess low achievement definitional variations and found that they lack sensitivity and coverage compared to a dual discrepancy definition.
The Medicaid Mandates of the 1980s: An Intergovernmental Perspective
Authors: Johnston Jocelyn M.
Published: December 2004

Medicaid, the health care program for the poor, has undergone significant changes in the last fifteen years. Many of those changes relate to the intergovernmental nature of the program. Medicaid is jointly operated, with the federal and state governments sharing program costs. Despite a set of program guidelines dictated by the federal government, states have traditionally had substantial latitude in Medicaid decisions. However, a series of developments in the 1980s led to increasing constraints on state Medicaid discretion, including federal mandates to expand Medicaid coverage. This article examines the inception and effectiveness of the Medicaid mandates from the perspective of interstate equity of health care services for poor families.
Public Finance and Budgeting in Korea under Democracy: A Critical Appraisal
Authors: Ha Yeon‐Seob
Published: December 2004

The Republic of Korea has been widely acknowledged as one of the few success stories of economic development in the second half of the twentieth century. The state has had a large role in guiding the economic development through policies and subsidization. However, with political democratization and economic liberalization, the politico‐economic context of Korea's public finance policy began to change dramatically. The purpose of this article is to analyze how Korea's public finance policy has changed under the newly installed democracy. It specifically discusses the public finance and budgeting policies during the Roh Tae Woo administration (1988–1992) and the Kim Young Sam administration (1993 to the present).
In Maryland, Fiscal Discipline Is the Budget Limit
Authors: Deschenaux Warren G.
Published: December 2004

Maryland does not limit spending or revenues pursuant to a constitutional or statutory formula. It has developed a unique response to fiscal difficulties, which does not abdicate fiscal policy to formulas as happens under traditional limitation regimes The process used in Maryland is called Spending Affordability, and it serves to cause policymakers to prospectively focus on the relationship of public spending to the state's economy without altering the budget‐making process. This article examines the Spending Affordability model in use in Maryland.
Lawyers for Conservative Causes: Clients, Ideology, and Social Distance
Authors: Heinz John P. , Paik Anthony , Southworth Ann
Published: December 2004

Scholars have devoted attention to “cause lawyers” on the political left, but lawyers who work on the conservative side of the American political spectrum have received relatively little academic consideration. This article presents systematic data on the characteristics of and relationships among lawyers affiliated with organizations active on a selected set of 17 conservative issues. We find that the lawyers serve several separate and distinct constituencies—business conservatives, Christian conservatives, libertarians, abortion opponents—and that the credentials of the lawyers serving these varying constituencies differ significantly. The greatest degree of social separation occurs between the business constituency and the abortion opponents, with another clear separation between libertarians and the interest groups devoted to traditional family values and order maintenance. The divisions among these constituencies appear to reflect the difference between “insider politics” and “populism,” which is manifested in part in actual geographic separation between lawyers located in the District of Columbia and those in the South, West, and Midwest. In the center of the network, however, we find some potential “mediators”—prominent lawyers who may facilitate communication and coordination among the several constituencies. These lawyers and the organizations they serve attempt to merge morality, market freedom, and individual liberty concerns, and they convene meetings of diverse sets of lawyers and organizational leaders to seek consensus on policy goals. Nonetheless, the findings indicate that most organizations are seldom active on issues that lie beyond the relatively narrow boundaries of their own interests.
Evaluating Legality: Toward a Cultural Approach to the Study of Law and Social Change
Authors: Kostiner Idit
Published: December 2004

The role of law in social change has been a subject of many academic debates. However, not much attention has been given to the contradictory ways in which activists for social change justify or criticize the use of law. Drawing on in-depth interviews with 25 social justice activists, I analyze the ways in which activists evaluate the role of law in social change. I find that activists invoke three distinct schemas of evaluation: instrumental, political, and cultural. The instrumental schema emphasizes change in the allocation of concrete resources; the political schema views change as the empowerment of marginalized communities; and the cultural schema emphasizes the transformation of assumptions that are shared by all members of society. Each schema provides activists with a particular order of justification that enables them to justify or to criticize the role of law in social change. While the multiplicity of schemas sustains the commonsense notion of law as a means for social change, it also accounts for possible changes in this notion.
Losers: Recovering Lost Property in Japan and the United States
Authors: West Mark D.
Published: December 2004

This article examines the lost property regime of Japan, which has one of the most impressive reputations in the world for returning lost property to its rightful owner, and compares it with that of the United States. Folk legend attributes Japanese lost-and-found success to honesty and other-regarding preferences. In this article, I focus on another possible explanation: legal institutions that efficiently and predictably allocate and enforce possessory rights. These recognized, centuries-old rules mesh with norms, institutional structures, and economic incentives to reinforce mutually the message that each sends and yields more lost-property recovery than altruism alone.
Fear of Gang Crime: A Look at Three Theoretical Models
Authors: Lane Jodi , Meeker James W.
Published: December 2004

Gang crime and resulting public fear became a major policy focus during the 1990s, yet few studies specifically focus on fear of gang crime. Guided by social disorganization theory, we test three theoretical models about the individual thought processes leading to fear of gang crime. Using structural equation models, we find that each of these three theories—diversity, disorder, and community concern—is an important predictor of gang-related fear. In addition, we find that the indirect relationships between demographic characteristics, theoretical variables, and fear depend upon which model is tested.
Prevalence, phenotype and genotype of oral enterococci
Authors: Sedgley C. M. , Lennan S. L. , Clewell D. B.
Published: December 2004

This study investigated the prevalence, phenotype and genotype of oral enterococci. Enterococci were detected in oral rinse samples from 11% of 100 patients receiving endodontic treatment and 1% of 100 dental students with no history of endodontic treatment (P = 0.0027). All enterococcal isolates were identified as Enterococcus faecalis. Viable counts ranged from 1 × 10 to 6 × 103 colony forming units per mL of oral rinse sample. Potential virulence traits expressed by oral E. faecalis strains included production of hemolysin (n = 4) and gelatinase (n = 4), and response to pheromones in E. faecalis culture filtrate (n = 1). Six strains produced bacteriocin. All strains were susceptible to ampicillin, benzylpenicillin, gentamicin and vancomycin. There was no evidence of metal‐ion resistance. One isolate produced hemolysin, gelatinase and bacteriocin, was resistant to several antibiotics, and responded to the pheromone cPD1. Pulsed‐field gel electrophoresis and plasmid analysis showed that oral E. faecalis exhibited widespread genetic polymorphism, with plasmids detected in seven strains.
Activation of multiple antiviral defence mechanisms by salicylic acid
Authors: Singh Davinder P. , Moore Catherine A. , Gilliland Androulla , Carr John P.
Published: December 2004

The plant signal molecule salicylic acid (SA) can induce resistance to a wide range of pathogen types. In the case of viruses, SA can stimulate the inhibition of all three main stages in virus infection: replication, cell‐to‐cell movement and long‐distance movement. Induction of resistance by SA appears to depend, in part, on downstream signalling via the mitochondrion. However, evidence has recently emerged that SA may stimulate a separate downstream pathway, leading to the induction of an additional mechanism of resistance based on RNA interference. In this review our aims are to document these recent advances and to suggest possible future avenues of research on SA‐induced resistance to viruses.
Potato oxysterol binding protein and cathepsin B are rapidly up‐regulated in independent defence pathways that distinguish R gene‐mediated and field resistances to Phytophthora infestans
Authors: Avrova Anna O. , Taleb Nawsheen , Rokka Veli‐Matti , Heilbronn Jacqueline , Campbell Edward , Hein Ingo , Gilroy Eleanor M. , Cardle Linda , Bradshaw John E. , Stewart Helen E. , Fakim Yasmina Jaufeerally , Loake Gary , Birch Paul R. J.
Published: December 2004

Suppression subtractive hybridization was used to isolate the genes which are specifically up‐regulated in the biotrophic phase of the incompatible interaction between a potato genotype, 1512 c(16), containing the resistance gene R2, and a Phytophthora infestans isolate containing the avirulence gene Avr2. Eight cDNAs were up‐regulated in the biotrophic phase of the incompatible interaction. Seven of these were also up‐regulated in the compatible interaction, but not until late in the necrotrophic phase. Amongst the sequences to be isolated were genes encoding the cysteine protease cathepsin B, StCathB, and an oxysterol binding protein, StOBP1; equivalent genes are involved in programmed cell death (PCD) processes in animals, but have yet to be implicated in such processes in plants. Whereas StOBP1 was up‐regulated early in potato plants containing either R gene‐mediated or moderate to high levels of field resistance, the highest levels of up‐regulation of StCathB were observed early in R gene‐mediated resistance but gradually increased from the early to late stages of field resistance, revealing these genes to be components of independent defence pathways and providing a means of distinguishing between these forms of resistance. StOBP1 was up‐regulated by oligogalacturonides (plant cell wall breakdown products generated by pectinase activities), indicating that it is also a component of a general, non‐specific defence pathway and is unlikely to play a role in PCD. In contrast, the expression of StCathB was unaffected by oligogalacturonide treatment, further associating its up‐regulation specifically with the gene‐for‐gene interaction.
Echinococcus multilocularis proliferation in mice and respective parasite 14‐3‐3 gene expression is mainly controlled by an αβ+ CD4+ T‐cell‐mediated immune response
Authors: Dai Wen Juan , Waldvogel Andreas , Siles‐Lucas Mar , Gottstein Bruno
Published: December 2004

The role of specific B lymphocytes and T‐cell populations in the control of experimental Echinococus multilocularis infection was studied in µMT, nude, T‐cell receptor (TCR)‐β–/–, major histocompatibility complex (MHC)‐I–/– and MHC‐II–/– mice. At 2 months postinfection, the parasite mass was more than 10 times higher in nude, TCR‐β–/– and MHC‐II–/– mice than in infected C57BL/6 wild‐type (WT) mice, and these T‐cell‐deficient mice started to die of the high parasite load at this time‐point. In contrast, MHC‐I–/– and µMT mice exhibited parasite growth rates similar to those found in WT controls. These findings clearly point to the major role that CD4+ αβ+ T cells play in limiting the E. multilocularis proliferation, while CD8+ T and B cells appeared to play a minor role in the control of parasite growth. In the absence of T cells, especially CD4+ or αβ+ T cells, the cellular immune response to infection was impaired, as documented by the lack of hepatic granuloma formation around the parasite and by a decreased splenocyte responsiveness to concanavalin A (Con A) and parasite antigen stimulation. Surprisingly, in T‐cell‐deficient mice, the ex vivo expression of interferon‐γ (IFN‐γ) and other inflammatory cytokines (except for interleukin‐6) were increased in association with a high parasite load. Thus, the relative protection mediated by CD4+ αβ+ T cells against E. multilocularis infection seemed not be IFN‐γ dependent, but rather to rely on the effector's function of CD4+ αβ+ T cells. The local restriction of parasite germinal cell proliferation was reflected by a regulatory effect on the expression of 14‐3‐3 protein within the parasite tissue in T‐cell‐deficient mice. These results provide a strong indication that the CD4+ αβ+ T‐cell‐mediated immune response contributes to the control of the parasite growth and to the regulation of production of the parasite 14‐3‐3 protein in metacestode tissues.
Investigation of alpha nascent polypeptide‐associated complex functions in a human CD8+ T cell ex vivo expansion model using antisense oligonucleotides
Authors: Al‐Shanti N. , Steward C. G. , Garland R. J. , Rowbottom A. W.
Published: December 2004

In order to determine molecules involved in the differentiation and proliferation of human CD8+ cells, two ex vivo expansion models were established: coculture of freshly purified human CD8+ cells with irradiated autologous feeders (AF) or stimulation with anti‐CD3. Two different proliferation kinetics of CD8+ cells and expression patterns of CD57 were observed between these conditions. Differential display reverse transcriptase–polymerase chain reaction was applied to investigate the differential expression of mRNA species between CD8+ CD57+ and CD8+ CD57– populations. A differentially expressed RNA species called alpha nascent polypeptide associated complex (α NAC) was found at a higher level in CD8+ CD57– cells than in CD8+ CD57+ cells. In the presence of AF, the expression of α NAC was reduced on culturing whilst proliferation increased. Similarly, in cultures stimulated with anti‐CD3, α NAC reverted to its inactive form and differentiation and proliferation increased. Using a phosphorothioate‐modified oligodeoxynucleotide antisense directed specifically against α NAC mRNA, protein expression was inhibited and increased CD8+ cell proliferation and CD25 expression were observed irrespective of the culture conditions. This suggests that α NAC protein is antiproliferative molecule. This is the first description of the function of the α NAC protein in human CD8+ T cells.
Understanding thymus‐independent antigen‐induced reduction of thymus‐dependent immune responses
Authors: Lindroth Karin , Mastache Elena Fernández , Roos Izaura , Fernández África González , Fernández Carmen
Published: December 2004

Deficiencies in immune responses against polysaccharides can have direct consequences for patients, and therefore, a better understanding of these immune reactions is crucial. We have studied the immune response against the polysaccharide dextran B512 (Dx). Administration of immunogenic doses of thymus‐independent (TI) Dx reduces the immunoglobulin G1 response to later challenges with a thymus‐dependent (TD) form of Dx. We investigated if this suppression is a general phenomenon caused not only by Dx but also by other TI antigens, and examined possible mechanisms contributing to this unresponsiveness. We show that clonal exhaustion is not involved in modulating subsequent responses, nor is signalling via FcγRIIB or other antibody mediated pathways. The reduced TD response is not an exclusive Dx phenomenon; it is also induced by TI antigen oxazolone (Ox). However, responses against the hapten dinitrophenyl (DNP) are not affected, indicating that the TI priming negative effect is not a general process. This may be explained by the restricted immune response to both Dx and Ox, in contrast to the unrestricted DNP response. Our conclusion from these experiments is that the underlying mechanism for the TI‐induced reduction of latter TD responses is a property of the TI activation itself.
Ca2+ influx shutdown in neutrophils induced by Fas (CD95) cross‐linking
Authors: Ayub Khurram , Laffafian Iraj , Dewitt Sharon , Hallett Maurice B.
Published: December 2004

In neutrophils, as in most other cell types, Ca2+ signalling is important for a number of cellular activities. Although inositol(1,4,5)trisphosphate‐mediated release of Ca2+ from intracellular stores is a necessary prelude, it is the Ca2+ influx that is responsible for many of the neutrophil responses. We report here that although elevations of cytosolic Ca2+ do not accompany Fas‐mediated apoptosis in neutrophils, the Ca2+ influx component of the response to N‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP) becomes selectively inactived as the neutrophils progress towards accelerated apoptosis induced by Fas (CD95) cross‐linking. After 4 hr incubation at 37°, untreated neutrophils display an exaggerated Ca2+ influx phase in response to FMLP. This was absent in neutrophils that had been Fas‐activated at the same time. No Ca2+ influx component was demonstrable by the removal of extracellular Ca2+ or by Ca2+ channel blockade with Ni2+ and no Mn2+ influx was detectable. The defect could not be attributed to a decrease in receptor sensitivity, receptor coupling or receptor number because the release of stored Ca2+ remained constant during incubation and was unaffected by Fas activation. Ca2+ influx became uncoupled from store release before detectable gross morphological changes or phosphatidyl serine externalization and was also insensitive to caspase 3 and 8 inhibitors. These results suggest a mechanism other than caspase‐mediated proteolytic damage to components important for Ca2+ influx.
An investigation of the ability of orally primed and tolerised T cells to help B cells upon mucosal challenge
Authors: Kobets Natalie , Kennedy Kim , O'Donnell Deborah , Garside Paul
Published: December 2004

Summary The oral delivery of soluble antigens induces unresponsiveness to systemic challenge that can be demonstrated as a reduced ability of tolerised T cells to support B‐cell expansion and antibody production. However, it remains controversial whether previously induced oral tolerance results in suppression or priming, or has no effect on B‐cell responses upon oral challenge. Using a double adoptive transfer system, we primed or tolerised T cells (independently of B cells) with a high dose of fed antigen, and examined the ability of these primed or tolerised T cells to support B‐cell clonal expansion in response to orally delivered conjugated antigen. We demonstrated directly in vivo that, in contrast to orally primed T cells, transgenic T cells tolerised by feeding a high dose of antigen are incapable of providing cognate help to support B‐cell clonal expansion and antibody production in response to oral challenge. This defect appears to be a result of a reduced ability of orally tolerised transgenic T cells to clonally expand and migrate to B‐cell follicles after oral challenge.
Multiple cleavage sites for polymeric immunoglobulin receptor
Authors: Asano Masatake , Takenouchi‐Ohkubo Nobuko , Matsumoto Naoyuki , Ogura Yoshitaka , Nomura Hirofumi , Suguro Hisashi , Moro Itaru
Published: December 2004

Human polymeric immunoglobulin receptor (pIgR) was expressed in baby hamster kidney (BHK) cells using a recombinant vaccinia virus transfection system. Cleavage of pIgR on the cell surface was partially inhibited by the proteinase inhibitor, leupeptin. We addressed the question whether some particular regions of pIgR could affect the efficient cleavage of this molecule, with the following results: (1) a mutant lacking the entire cytoplasmic region resulted in release of secretory component (SC) into the culture supernatant much faster than wild‐type; (2) a pIgR mutant lacking the entire extracellular domain 6, the region containing the susceptible cleavage sites, could be cleaved and released as a mutant SC. The transport kinetics of this mutant between endoplasmic reticulum (ER) and Golgi or Golgi and the cell surface was equivalent to wild‐type pIgR. Our results indicate that although the main cleavage site is in domain 6, at least one other cleavage site may exist.
Ubiquitin‐fusion degradation pathway plays an indispensable role in naked DNA vaccination with a chimeric gene encoding a syngeneic cytotoxic T lymphocyte epitope of melanocyte and green fluorescent protein
Authors: Zhang Manxin , Ishii Kazunari , Hisaeda Hajime , Murata Shigeo , Chiba Tomoki , Tanaka Keiji , Li Yang , Obata Chikage , Furue Masutaka , Himeno Kunisuke
Published: December 2004

Antitumour immunity against murine melanoma B16 was achieved by genetic immunization with a naked chimeric DNA encoding a fusion protein linking green fluorescent protein (GFP) to the N‐terminus of a major CD8+ cytotoxic T lymphocyte (CTL) epitope of tyrosinase‐related protein 2 (TRP‐2181−188) of murine melanoma, designated as pGFP‐TRP‐2. Tumour growth was profoundly suppressed in C57BL/6 mice immunized with pGFP‐TRP‐2, while mice vaccinated with pTRP‐2 showed rapid tumour growth and died within 40 days after tumour challenge. Splenocytes of mice immunized with pGFP‐TRP‐2 showed high CTL activity specific for TRP‐2181−188. GFP‐TRP‐2 expressed in COS‐7 cells was rapidly degradated in vitro and the degradation was almost completely prevented by adding a proteasome inhibitor, MG‐132, in the culture. Furthermore, the antimelanoma immunity induced by genetic immunization with pGFP‐TRP‐2 was completely cancelled in mice deficient in proteasome activator PA28α/β. Taken together, GFP‐TRP‐2 processed by cytosolic proteasome played a central role in breaking peripheral tolerance to a melanoma/melanocyte antigen, TRP‐2181−188, by activating CD8+ CTL specific for TRP‐2181−188. TRP‐2181−188 fused to GFP may be readily cut off from GFP by the ubiquitin‐fusion degradation (UFD) pathway and efficiently presented to major histocompatibility complex class I molecules, resulting in effective induction of CD8+ T cells specific for the CTL epitope. Furthermore, CD4+ T cells specific for GFP were shown to play a crucial role in the antimelanoma immunity, probably potentiating activity of TRP‐2‐specific CTL and/or the ‘ubiquitin‐proteasome pathway’. It is noteworthy to document that genetic immunization with pGFP plus pTRP‐2181−188 failed to exert the antitumour immunity.
Cross‐presentation: dendritic cells and macrophages bite off more than they can chew!
Authors: Brode Sven , Macary Paul A.
Published: December 2004

As immunologists, our knowledge of the molecular mechanisms which underlie the presentation of antigens derived from extracellular or ‘exogenous’ sources to CD8 cytotoxic lymphocytes (CTL) has been limited. This process, termed ‘cross‐presentation’, has been linked to the elicitation of protective CTL responses against tumours and may be extremely important in generating immune responses against clinically relevant pathogens that do not infect tissues of haemopoietic origin. It is now known that cross‐presentation of exogenous antigens on major histocompatibility complex (MHC) class I occurs through several distinct cellular pathways. In this review we outline and discuss some recent advances in our understanding of these pathways.
Enteroaggregative Escherichia coli flagellin‐induced interleukin‐8 secretion requires Toll‐like receptor 5‐dependent p38 MAP kinase activation
Authors: Khan Mohammed A. S. , Kang Jian , Steiner Theodore S.
Published: December 2004

Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen that causes acute and chronic diarrhoea in a number of clinical settings. EAEC diarrhoea involves bacterial aggregation, adherence to intestinal epithelial cells and elaboration of several toxigenic bacterial mediators. Flagellin (FliC‐EAEC), a major bacterial surface protein of EAEC, causes interleukin (IL)‐8 release from several epithelial cell lines. The host response to flagellins from E. coli and several other bacteria is mediated by Toll‐like receptor 5 (TLR5), which signals through nuclear factor kappa B (NF‐κB) to induce transcription of pro‐inflammatory cytokines. p38 mitogen‐activating protein (MAP) kinase (MAPK) is a member of a family of stress‐related kinases that influences a diverse range of cellular functions including host inflammatory responses to microbial products. We studied the role of p38 MAPK in FliC‐EAEC‐induced IL‐8 secretion from Caco‐2 human intestinal epithelial cells and THP‐1 human monocytic cells. We found that IL‐8 secretion from both cell types is dependent on p38 MAPK, which is phospho‐activated in response to FliC‐EAEC. The role of TLR5 in p38 MAPK‐dependent IL‐8 secretion was verified in HEp‐2 cells transiently transfected with a TLR5 expression construct. Activation of interleukin‐1 receptor‐associated kinase (IRAK) was also observed in Caco‐2 and TLR5‐transfected HEp‐2 cells after exposure to FliC‐EAEC. Finally, we demonstrated that pharmacological inhibition of p38 MAPK reduced IL‐8 transcription and mRNA levels, but did not affect NF‐κB activation. Collectively, our results suggest that TLR5 mediates p38 MAPK‐dependent IL‐8 secretion from epithelial and monocytic cells incubated with FliC‐EAEC, and that this effect requires IL‐8 promoter activation independent of NF‐κB nuclear migration.
The increased prevalence of allergy and the hygiene hypothesis: missing immune deviation, reduced immune suppression, or both?
Authors: Romagnani Sergio
Published: December 2004

Allergic atopic disorders, such as rhinitis, asthma, and atopic dermatitis, are the result of a systemic inflammatory reaction triggered by type 2 T helper (Th2) cell‐mediated immune responses against ‘innocuous’ antigens (allergens) of complex genetic and environmental origin. A number of epidemiological studies have suggested that the increase in the prevalence of allergic disorders that has occurred over the past few decades is attributable to a reduced microbial burden during childhood, as a consequence of Westernized lifestyle (the ‘hygiene hypothesis’). However, the mechanisms by which the reduced exposure of children to pathogenic and nonpathogenic microbes results in enhanced responses of Th2 cells are still controversial. The initial interpretation proposed a missing immune deviation of allergen‐specific responses from a Th2 to a type 1 Th (Th1) profile, as a result of the reduced production of interleukin‐12 and interferons by natural immunity cells which are stimulated by bacterial products via their Toll‐like receptors. More recently, the role of reduced activity of T regulatory cells has been emphasized. The epidemiological findings and the experimental evidence available so far suggest that both mechanisms may be involved. A better understanding of this question is important not only from a theoretical point of view, but also because of its therapeutic implications.
Divide and conquer: the importance of cell division in regulating B‐cell responses
Authors: Tangye Stuart G. , Hodgkin Philip D.
Published: December 2004

Proliferation is an essential characteristic of clonal selection and is required for the expansion of antigen reactive clones leading to the development of antibody of different isotypes and memory cells. New data for mouse and human B cells point to an important role for division in regulating isotype class and in optimizing development of protective immunity by the regulated entry of cells to the plasma cell lineage.
Foraging inequalities in large groups: quantifying depletion experienced by individuals in goose flocks
Authors: Rowcliffe J. Marcus , Pettifor Richard A. , Carbone Chris
Published: December 2004

Inequalities between individuals represent a major force driving patterns of animal dispersion. Here we use a novel approach to the analysis of feeding competition in large groups, based on photographic sequences of barnacle goose flocks over time. The spatial distributions of individuals derived from these photos were used to describe how individual feeding performance may be affected by patch depletion caused by other members of the flock. This was assessed indirectly by estimating the variation in prior grazing time experienced by individuals.

The most successful foragers in a flock (i.e. those experiencing the least prior grazing time) are largely unaffected by depletion arising during the life span of the flock, while the least successful foragers experience very substantial depletion. Furthermore, for the less successful individuals, the average level of depletion increases continuously with both flock size and time spent in the flock.

Skew in depletion experienced could not be assessed accurately, although it is likely that there is moderate right skew, i.e. a few individuals do very badly, but more than half do better than the mean.

This study suggests that the degree of depletion experienced is related to position within the group, while previous studies of this system have shown that there is strong competition for the better positions. Dominance status is therefore likely to be a strong determinant of feeding performance. Subordinate individuals, being unable to obtain leading positions, may be forced to adopt alternative strategies to improve feeding performance, such as moving more frequently in order to maximize time in smaller or more recently formed groups.
Modelling the joint effects of predator and prey diversity on total prey biomass
Authors: Fox Jeremy W.
Published: December 2004

Niche differentiation is widely thought to promote both coexistence of many species within a trophic level, and higher total biomass of those species. However, the joint effects of changes in diversity within multiple trophic levels are unknown. The potential for niche differences to promote high diversity and biomass within a trophic level may depend on the diversity and composition of adjacent trophic levels.

Using a simple mechanistic model, I examine the joint consequences of changes in diversity on two adjacent trophic levels (‘predators’ and ‘prey’) for the total biomass of prey. Niche differences among prey reflect a trade‐off between ability to compete for resources and ability to avoid/sustain predation. Niche differences among predators reflect differences in ability to consume different prey species.

Total prey biomass is a complex, joint function of prey and predator diversity. In particular, transgressive overyielding (when a diverse polyculture of prey outperforms any prey monoculture) can occur for some parameter values when a specialist predator mediates prey coexistence, and for a different set of parameter values when a specialist and a generalist predator together mediate prey coexistence, but is impossible when a generalist predator alone mediates prey coexistence.

Increased initial predator diversity tends to reduce total prey biomass even when predators cannot coexist, due to a ‘selection’ effect for the most effective predator. Predators coexist only in prey polycultures. Coexisting predators can, but do not necessarily, reduce total prey biomass to a lower level than could any predator alone.

The niche differences that permit coexistence strongly constrain the rank order of total prey biomass across all prey and predator combinations. Knowledge of the key trade‐offs that promote coexistence within food webs can allow powerful qualitative predictions of the effects of species loss on ecosystem‐level properties such as total biomass.
The role of competition in adaptive radiation: a field study on sequentially ovipositing host‐specific seed predators
Authors: Després Laurence , Cherif Mehdi
Published: December 2004

We propose an alternative model to the host‐shifting model of sympatric speciation in plant–insect systems. The role of competition in driving ecological adaptive radiation was evaluated in a seed predator exploiting a single host‐plant species. Sympatric speciation may occur through disruptive selection on oviposition timing if this shift decreases competition among larvae feeding on seeds.

The globeflower flyChiastochetapresents a unique case of adaptive radiation, with at least six sister species co‐developing in fruits ofTrollius europaeus. These species all feed on seeds, and differ in their oviposition timing, one species ovipositing in 1‐day‐old flowers (early species), while all the other species sequentially oviposit throughout the flower life span (late species). We evaluated the impact of conspecific and heterospecific larvae on larval installation success, and on larval fresh mass and area, for early and late species, in natural conditions.

None of the three larval traits measured was correlated with fruit size, and no fruit lost all seeds to predation, suggesting that seed availability was not a limiting factor for larval development.

Our results show strong intraspecific competition among early larvae for larval installation, and among late larvae for larval mass. By contrast, larval competition between species was weak. These results are consistent with the hypothesis that shifts in oviposition promoted rapid radiation in globeflower flies by lowering competition among larvae.
Preferences for sugars and amino acids and their conditionality in a diverse nectar‐feeding ant community
Authors: Blüthgen Nico , Fiedler Konrad
Published: December 2004

Feeding preferences of nectarivorous ants for sugars and amino acids were studied in an Australian tropical rain forest using artificial nectar solutions. Fifty‐one ant species were recorded feeding on the solutions.

Preferences among carbohydrates were principally concordant between ant species. In paired tests, sucrose was often preferred over fructose, glucose, maltose, melezitose, raffinose and xylose, respectively. Attractiveness of sucrose baits increased with concentration.

Many ant species preferred sugar solutions containing mixtures of amino acids over pure sugar solutions. However, preferences among seven pairs of single amino acids in sugar solutions differed substantially between ant species, including several cases where different ant species displayed significant opposite choices.

Ant selectivity between solutions was significantly reduced when different ant species co‐occurred on the same bait. Preferences for single amino acids were also reduced when colonies fed extensively on the same compound prior to the experiment for 2 days.

Our results indicate that both interspecific variability in gustatory preferences and conditional effects such as competition and colony requirements affect resource selection in multispecies communities. These processes may be crucial in niche partitioning of species‐rich nectarivore assemblages.
Individual access to preferred habitat affects fitness components in female roe deer Capreolus capreolus
Authors: Nilsen Erlend B. , Linnell John D. C. , Andersen Reidar
Published: December 2004

Many studies have reported variation in life‐history traits and reproductive success within populations. One potential source for the reported variation is fine‐scale spatial variation in habitat quality.

In this study the effects of differences in home‐range quality on individual fitness were investigated in a roe deer population in an agricultural–woodland mosaic landscape in central Norway.

Compositional analysis revealed that woodland was the most preferred habitat: its availability was therefore used as an index of home‐range quality.

It was found that the quality of the does’ winter home‐range affected fawn production in the subsequent spring, as females with greatest availability of preferred habitat during winter produced the larger litters the subsequent spring.

Furthermore, the winter weights of the fawns seemed to be affected by home‐range quality in a complex way. First, home‐range quality in the prenatal winter seems to influence the birthdate and in turn the weight of the fawns in August. Also there was an immediate effect of the quality of the home‐range that the fawns occupied during the postnatal winter.

These results are not consistent with the ideal free distribution theory, suggesting that the mechanisms for roe deer spacing behaviour should be re‐examined.
Alien species and interspecific competition: effects of introduced eastern grey squirrels on red squirrel population dynamics
Authors: Gurnell John , Wauters Luc A. , Lurz Peter W. W. , Tosi Guido
Published: December 2004

Throughout much of Britain, Ireland and north Italy, red squirrels (Sciurus vulgaris L.) have been replaced by alien grey squirrels (S. carolinensis Gmelin) introduced from North America. We have studied squirrels in two mixed woodlands in north Italy and two conifer forests in north England. In each country, one site was occupied by red squirrels and one site by both species.

We have previously considered interference competition and exploitation competition for food and space between red and grey squirrels and have showed that grey squirrels caused reduced body growth in juvenile and subadult red squirrels, and compete for tree seeds cached by adult red squirrels in spring. Here we report on the effects of grey squirrels on three fitness components in red squirrels that have consequence at the population level: fecundity, residency and recruitment.

Litter production peaked in the spring and summer, but fewer females bred in the summer with grey squirrels present. In addition, fewer individual red squirrel females produced two litters per year in the sites with grey squirrels. Moreover, red squirrel recruitment rate and, in the mixed broadleaf sites, red squirrel juvenile residency, decreased with increasing grey squirrel density.

Fecundity of individual female red squirrels was lower in red–grey than in red‐only sites because they had a lower body mass in sites with grey squirrels.

Overall, there was no significant effect of grey squirrels on residency of adult red squirrels or on population turnover rate. However, the presence of grey squirrels resulted in a reduction in red squirrel fitness which was evident by lower population summer breeding and a lower recruitment. Over time, this will result in a decline in population size and eventually population extinction.
Within‐sex density dependence and population dynamics of red squirrels Sciurus vulgaris
Authors: Wauters Luc A. , Matthysen Erik , Adriaensen Frank , Tosi Guido
Published: December 2004

Social organization and dispersal of red squirrels (Sciurus vulgaris L.) differ between sexes, and intrasexual competition is intense. Therefore, we predicted that demographic parameters should be gender‐specific: that is density‐dependent factors will be more strongly related to density of the same sex than to density of the opposite sex. We studied the relative importance of within‐ and between‐sex density‐dependent factors and of density‐independent factors (habitat type, food abundance, winter temperature) on different demographic parameters, in two populations in northern Belgium.

Spring density of males was positively correlated with tree‐seed abundance in the previous year, but this was not the case for females. None of the population parameters we measured differed between habitats, indicating that the same density‐dependent and density‐independent mechanisms prevailed in coniferous and deciduous habitat.

Within each sex, we found several demographic parameters that were dependent on the densities of the same sex; however, none of these parameters was found to be dependent on the density of the opposite sex.

Reproductive rate increased with food abundance and decreased with female density. Adult survival of females decreased with female density in autumn–winter, while survival of adult males in spring–summer increased with the size of the previous year's seed crop.

Immigration rate of males was higher in spring than in autumn, and spring immigration increased with food abundance. Male recruitment rate, in both seasons, increased with food abundance, but was male density dependent. However, spring–summer loss rates also increased when food supplies were good, suggesting that despite high food availability, emigration of juvenile and subadult males increased when intrasexual competition was intense. Recruitment rate of females decreased with increasing female density. After a good seed crop, more subadult females dispersed, but their settlement success (recruitment) was lower at high female density.

Seed crop size positively affected red squirrel densities through increased reproduction, immigration and adult survival of males, but density‐dependent reproduction and within‐sex density‐dependent recruitment of locally born juveniles and dispersing subadults limit the fluctuations in numbers and regulate densities in winter–early spring, as well as in summer.
Connectivity and homogenisation of population sizes: an experimental approach in Lacerta vivipara
Authors: Lecomte Jane , Boudjemadi Katia , Sarrazin François , Cally Karine , Clobert Jean
Published: December 2004

At regional scales, dispersal is known to prevent metapopulation extinction by buffering stochastic processes. Theory predicts that connectivity, through density‐dependent dispersal rates, should spatially homogenize population density and synchronize local population dynamics in the long term. However, empirical evidence for the effect of connectivity on synchrony and local population dynamics remains scarce.

We experimentally manipulated connectivity in order to investigate the homogenisation effect on population size. The experimental design consisted of 16 patches of common lizard populations (Lacerta vivipara), half of which were connected by dispersal. The design allowed us to identify candidates for dispersal in unconnected patches.

We found that population sizes became spatially more and more homogeneous with time in connected patches, whereas extinctions or demographic explosions were observed in unconnected patches. Juvenile dispersal was density‐dependent in connected patches but not in unconnected ones. These results suggest that the loss of connection modifies population functioning by influencing how dispersal is determined by local conditions.

Finally, population explosions in unconnected patches were followed by a sharp decrease in population size. So non‐extinct, unconnected populations did not stabilize. This could be due to over‐compensatory density dependence.

Population viability analysis models suggest that environmental stochasticity and catastrophic events, in addition to the density‐dependent process, are required to explain population size variation and extinction.
Peripheral parenteral nutrition in a case of chyle leak following neck dissection
Authors: Morris S. A. , Taylor S. J.
Published: December 2004

Chylothorax is an uncommon condition which is potentially life‐threatening if untreated. The following case study of a 75‐year‐old man with chyle leak following surgery shows how prompt dietetic action prevented further compromise in immune function and nutritional status. Dietetic recommendation to minimize enteral intake rapidly stopped chyle flow and promoted wound closure. Peripheral parenteral nutrition (PPN) was administered in order to prevent malnutrition. There is limited literature available for evidence of best practice for cases of chyle leakage, however, this particular case demonstrates PPN should be considered despite the potential risks.
The long‐term effect of dietary advice on the diet of men with angina: the diet and angina randomized trial
Authors: Ness A. R. , Ashfield‐Watt P. A. L. , Whiting J. M. , Smith G. D. , Hughes J. , Burr M. L.
Published: December 2004

Introduction  The long‐term effects on diet of dietary advice to eat fruit and vegetables or fatty fish are not well described.

Materials and methods  From 1990 to 1996 3114 men aged 37–70 with treated angina were recruited from general practices in South Wales. A dietitian randomly allocated the eligible men to receive advice to eat more fruit and vegetables, or advice to eat more fatty fish, or both these types of advice or neither. In 2000, a brief self‐completion questionnaire was sent to a sample of 1191 of the men known to be alive at the end of March 1999.

Results  The questionnaire was returned by 944 of the 1036 men alive at the time the questionnaire was sent. Those given fish advice were consuming more fatty fish but the difference was modest 21.9 g day−1 vs. 14.0 g day−1 (P < 0.01). The differences in fruit and vegetables intake between those given fruit advice and those not given fruit advice were small 373.2 g day−1 vs. 351.7 g day−1 (P = 0.05).

Discussion  Men of this age group may be particularly resistant to fruit and vegetables advice; population‐based interventions or interventions targeted at women might be more effective.