bluuebunny/crossref_metadata_2025_split huggingface dataset:
The classical and alternative pathways of complement activation play distinct roles in spontaneous C3 fragment deposition and membrane attack complex (MAC) formation on human B lymphocytes
Authors: Leslie Robert Graham Quinton , Nielsen Claus Henrik 
Published: December 2003

SummaryThe contributions of the classical (CP) and alternative (AP) pathways of complement activation to the spontaneous deposition of C3 fragments and the formation of membrane attack complexes (MAC) on human B lymphocytes, were assessed by incubating peripheral blood mononuclear cells with autologous serum in the absence and presence of selective inhibitors of the AP and CP, respectively. While the total amount of C3 fragments deposited was relatively unaffected by blocking either pathway individually, deposition was virtually abrogated by their combined blockade. A marked difference was observed, however, in the nature of the fragments deposited as a result of CP and AP activation: C3b fragments deposited via the CP were extensively (∼ 90%) converted to the terminal degradation product, C3dg, whereas about 50% of those deposited by the AP persisted as C3b/iC3b fragments. The extent of MAC formation was also found to be highly pathway dependent, with the AP being about 15‐fold more efficient at initiating this process than the CP. A model accounting for the effectiveness of the AP in both preserving C3 fragment integrity and initiating MAC is presented.
Differential production of cytokines, reactive oxygen and nitrogen by bovine macrophages and dendritic cells stimulated with Toll‐like receptor agonists
Authors: Werling Dirk , Hope Jayne C. , Howard Chris J. , Jungi Thomas W. 
Published: December 2003

SummaryToll‐like receptors (TLR) have been described as partially sharing signalling pathways but showing unique ligand specificity and tissue distribution. Here, the response of bovine macrophages (Mφ) and dendritic cells (DC), both derived from monocytes, was compared by exposing them to the TLR‐specific ligands lipopolysaccharide, poly(I:C)‐double‐stranded RNA, and CpG‐DNA, as well as inactivated Gram‐negative and Gram‐positive bacteria, shown to bind to TLR. The production of NO, superoxide anion, interleukin‐10 (IL‐10), IL‐12 and tumour necrosis factor (TNF) was determined. Compared to monocytes, Mφ expressed more TLR2 and similar levels of TLR4 mRNA transcripts, as analysed by quantitative polymerase chain reaction, whereas DC expressed reduced amounts. Although both DC and Mφ recognized the TLR ligands, dramatic differences were seen in their reaction pattern to them. Both cell types responded with the production of TNF, but DC produced more IL‐12, whereas Mφ produced more IL‐10, regardless of the TLR agonist used. Co‐stimulation with interferon‐γ influenced the amount of cytokine production, but did not alter the cell type‐specific response pattern. Compared to Mφ, DC produced > 10 times less NO upon triggering with TLR ligands. In addition, DC produced superoxide anion to opsonized and non‐opsonized zymosan, but not to phorbol 12‐myristate 13‐acetate, a response pattern confirmed for human Mφ and DC, respectively. Different protein kinase C isoforms and extracellular signal‐regulated kinase patterns were detected in cell lysates of resting and stimulated Mφ and DC. Collectively, our results point to profound differences in pathogen‐derived signal–response coupling occurring commensurate with distinct functions carried out by Mφ or DC.
Surfactant protein A, an innate immune factor, is expressed in the vaginal mucosa and is present in vaginal lavage fluid
Authors: MacNeill Colin , Umstead Todd M. , Phelps David S. , Lin Zhenwu , Floros Joanna , Shearer Debra A. , Weisz Judith 
Published: December 2003

SummarySurfactant protein A (SP‐A), first identified as a component of the lung surfactant system, is now recognized to be an important contributor to host defence mechanisms. SP‐A can facilitate phagocytosis by opsonizing bacteria, fungi and viruses, stimulate the oxidative burst by phagocytes and modulate pro‐inflammatory cytokine production by phagocytic cells. SP‐A can also provide a link between innate and adaptive immune responses by promoting differentiation and chemotaxis of dendritic cells. Because of the obvious relevance of these mechanisms to the host defence and ‘gate keeping’ functions of the lower genital tract, we examined human vaginal mucosa for SP‐A protein and transcripts and analysed vaginal lavage fluid for SP‐A. By immunocytochemistry, SP‐A was identified in two layers of the vaginal epithelium: the deep intermediate layer (the site of newly differentiated epithelial cells); and the superficial layer (comprising dead epithelial cells), where SP‐A is probably extracellular and associated with a glycocalyx. Transcripts of SP‐A were identified by Northern blot analysis in RNA isolated from vaginal wall and shown, by sequencing of reverse transcription–polymerase chain reaction products, to be derived from each of the two closely related SP‐A genes, SP‐A1 and SP‐A2. SP‐A was identified in vaginal lavage fluid by two‐dimensional gel electrophoresis, and confirmed by mass spectrometry. This study provides evidence, for the first time, that SP‐A is produced in a squamous epithelium, namely the vaginal mucosa, and has a localization that would allow it to contribute to both the innate and adaptive immune response. The findings support the hypothesis that in the vagina, as in lung, SP‐A is an essential component of the host‐defence system. A corollary hypothesis is that qualitative and quantitative alterations of normal SP‐A may play a role in the pathogenesis of lower genital tract inflammatory conditions.
In vivo, RFX5 binds differently to the human leucocyte antigen‐E, ‐F, and ‐G gene promoters and participates in HLA class I protein expression in a cell type‐dependent manner
Authors: Rousseau Philippe , Masternak Krzysztof , Krawczyk Michal , Reith Walter , Dausset Jean , Carosella Edgardo D. , Moreau Philippe 
Published: December 2003

SummaryWe analysed the regulation of human leucocyte antigen (HLA)‐E, ‐F and ‐G genes, focusing on the SXY module, a promoter region that controls major histocompatibility complex (MHC) class II expression and participates in the expression of classical HLA class I molecules. It comprises the X1, X2 and Y boxes, bound by RFX, X2‐BP/ATF/CREB and NFY factors, respectively. The complex recruits the master control factor CIITA. The SXY module is conserved in HLA‐E and HLA‐F gene promoters, whereas in the HLA‐G promoter, the only conserved boxes are S and X1. Chromatin immunoprecipitation assays, performed on HLA‐G positive and negative cell lines, demonstrated the in situ binding of RFX5 and CIITA to HLA‐E and HLA‐F, but not to HLA‐G, promoters. In B cells from bare lymphocyte syndrome patients lacking RFX5 or CIITA, we observed lower steady‐state levels of HLA‐E and HLA‐F transcripts but did not find any significant decrease in the cell‐surface expression of HLA‐E/classical HLA class I. In RFX5‐deficient fibroblasts, the cell‐surface expression of HLA molecules was decreased. RFX5 and CIITA are thus not involved in HLA‐G expression and their importance for the surface expression of HLA‐E/classical HLA class I molecules may vary depending on the cell type.
Efficient induction of T helper type 1‐mediated immune responses in antigen‐primed mice by anti‐CD3 single‐chain Fv/interleukin‐18 fusion DNA
Authors: Kim E. J. , Cho D. , Kim T. S. 
Published: December 2003

SummaryTwo types of T helper (Th) cells – Th1 and Th2 – play different roles in protection and immunopathology. The Th1 cell‐mediated immune response plays an important role in inducing the host defence against intracellular bacteria and also in cancer immunotherapy. To effectively induce Th1 immune responses, we constructed a mammalian expression plasmid (pAnti‐CD3sFv/IL‐18) carrying a fusion gene in which anti‐CD3 single‐chain Fv (sFv) cDNA, the smallest unit of antibody recognizing the CD3 epsilon moiety of the T‐cell receptor, was covalently linked to mature interleukin (IL)‐18 cDNA. Intramuscular injection of ovalbumin (OVA)‐sensitized BALB/c mice with pAnti‐CD3sFv/IL‐18 DNA efficiently increased the production of both OVA‐specific interferon‐γ and anti‐OVA immunoglobulin G2a, compared to injection with pAnti‐CD3sFv DNA. In addition, pAnti‐CD3sFv/IL‐18 was more efficient than a mixture of pAnti‐CD3sFv + pIL‐18 in inducing OVA‐specific, Th1 immune responses and also in inhibiting OVA‐specific, IL‐4 production. These studies indicate that vaccination with pAnti‐CD3sFv/IL‐18 fusion DNA efficiently induces the Th1 immune response in antigen‐sensitized mice.
Intracellular expression of interleukin‐4 and interferon‐γ by a Mycobacterium tuberculosis antigen‐stimulated CD4+ CD57+ T‐cell subpopulation with memory phenotype in tuberculosis patients
Authors: Jiménez‐Martínez Maria C. , Linares Marisela , Báez Renata , Montaño Luis F. , Martínez‐Cairo Salvador , Gorocica Patricia , Chávez Raúl , Zenteno Edgar , Lascurain Ricardo 
Published: December 2003

SummaryIn some chronic pathological conditions, antigen persistence activates and expands the CD4+ CD57+ T‐cell subset. The host immune response against tuberculosis infection is maintained through the continuous presence of antigen‐stimulated effector/memory helper T cells. To determine whether CD4+ CD57+ T cells were also expanded in human tuberculosis, we analysed (by flow cytometry) the phenotype of peripheral blood CD4+ T cells from 30 tuberculosis patients and 30 healthy controls. We observed a significant increase in the CD4+ CD57+ T‐cell subset in tuberculosis patients in comparison to healthy controls (P < 0·001). Most CD4+ CD57+ T cells exhibited a CD28− CD45RO+ CD62L− phenotype, which is associated with memory cells. In vitro, a higher number of antigen‐stimulated CD4+ CD57+ T cells produced intracellular interferon‐γ and interleukin‐4 compared with antigen‐stimulated CD4+ CD57− T cells (P < 0·001). These findings suggest that the majority of CD4+ CD57+ T cells correspond to a phenotype of activated memory T cells.
Nerve fibres are required to evoke a contact sensitivity response in mice
Authors: Beresford Lorna , Orange Oliver , Bell Eric B. , Miyan Jaleel A. 
Published: December 2003

SummaryPrevious work has indicated that the dermis and epidermis of skin contains abundant nerve fibres closely associated with Langerhans' cells. We have investigated whether these nerve endings are necessary for inducing and evoking a contact sensitivity (CS) response. Topical application of a general or a peptide (calcitonin gene‐related peptide and substance P)‐specific neurotoxin was employed to destroy the nerve fibres at skin sites subsequently used to induce or evoke the CS response. Elimination of nerve fibres abolished both induction and effector stages of the specific CS response. Denervation did not destroy the local Langerhans' cells, which were observed in increased numbers, or prevent them from migrating to lymph nodes. The local CS response was also abolished by systemic deletion of capsaicin‐sensitive nerve fibres, suggesting that the loss of response was not non‐specific but associated with the loss of specific nerve fibres. The results indicate that peptidergic nerve fibres are required to elicit a CS response and may be vital to the normal function of the immune system.
Co‐administration of CD40 agonistic antibody and antigen fails to overcome the induction of oral tolerance
Authors: Chung Yeonseok , Kim Dong‐Hyeon , Lee Seung‐Ho , Kang Chang‐Yuil 
Published: December 2003

SummaryT‐cell stimulation in the absence of a second, costimulatory signal can lead to anergy or deletion. There is growing evidence that peripheral tolerance to an exogenous antigen might be caused by the lack of costimulatory molecules on antigen‐presenting cells (APCs). In the present study, we examined whether tolerance against orally administered antigen could be reversed by maturation of APCs via CD40 signalling. Monoclonal antibody (mAb) to CD40 efficiently induced costimulatory molecules on APCs. Treatment with anti‐CD40 mAb potentiated the division of ovalbumin‐specific T cells in response to oral ovalbumin in secondary lymphoid organs. However, such treatment did not prolong the presentation of oral ovalbumin on APCs. Surprisingly, treatment of anti‐CD40 mAb at the time of oral administration of ovalbumin did not reverse the induction of tolerance to ovalbumin in either the high‐ or low‐dose regimens. Furthermore, the induction of oral tolerance in our model is not the result of negative signalling by cytotoxic T‐lymphocyte antigen‐4. These results indicate that tolerance for oral antigen could be established regardless of APC maturation by a CD40‐specific mAb, suggesting that there could be a unique mechanism to regulate immunity versus tolerance to encountered antigen in the gut‐associated lymphoid tissue.
An individual behaviour‐based model can predict shorebird mortality using routinely collected shellfishery data
Authors: Stillman Richard A. , West Andrew D. , Goss‐Custard John D. , Caldow Richard W. G. , Mcgrorty Selwyn , Durell Sarah E. A.Le V. Dit , Yates Michael G. , Atkinson Philip W. , Clark Nigel A. , Bell Michael C. , Dare Peter J. , Mander Matt 
Published: December 2003

SummaryThe debate over the interaction between shellfishing and shorebirds is long‐running. Behaviour‐based models predict how animal populations are influenced by environmental change from the behavioural responses of individual animals to this change. These models are a potential tool for addressing shellfishery problems, but to be of value they must produce reliable predictions using data that are readily available or can be collected relatively quickly.We parameterized a behaviour‐based model for the oystercatcher population of the Wash, UK, for 1990–99 using data from shellfishery (mussels and cockles), shorebird and climate monitoring schemes. During the 1990s the overwinter mortality rates of Wash oystercatchers varied widely. The model correctly identified the years in which the observed overwinter mortality was either low (1–2%) or high (10–26%) from annual variation in the food supply, oystercatcher population size and temperature.Many oystercatchers were observed and predicted to die when only a fraction of the available food was consumed. Within the model at least, this was because interference competition excluded the least dominant birds from part of the food supply and the least efficient foragers died before the food supply was fully depleted. A simplified model, which excluded interference and individual variation, incorrectly predicted that all birds survived in all years. Models that exclude these two components of behaviour will tend to underestimate the effect of mussel and cockle food shortage on oystercatchers. Shellfishery management based on such predictions may cause high oystercatcher mortality rates even though enough food would appear to be reserved for the birds.Synthesis and applications. This study shows how a behaviour‐based model can be parameterized and predict annual variation in oystercatcher mortality using data routinely collected from the Wash. The principle on which the model is based, that animals behave in order to maximize their chances of survival and reproduction, applies to any system, and the shellfishery, bird and climate data used to parameterize the model are widely available. The model can be used to advise how to manage shellfisheries, by predicting the proportion of the stock that needs to remain unfished in order to maintain low oystercatcher mortality rates.
Responses of periphyton and insects to experimental manipulation of riparian buffer width along forest streams
Authors: Kiffney Peter M. , Richardson John S. , Bull Jennifer P. 
Published: December 2003

SummaryRiparian trees regulate aquatic ecosystem processes, such as inputs of light, organic matter and nutrients, that can be altered dramatically when these trees are harvested. Riparian buffers (uncut strips of vegetation) are widely used to mitigate the impact of clear‐cut logging on aquatic ecosystems but there have been few experimental assessments of their effectiveness.Forests along 13 headwater stream reaches in south‐western British Columbia, Canada, were clear‐cut in 1998, creating three riparian buffer treatments (30‐m buffer, 10‐m buffer and clear‐cut to the stream edge), or left as uncut controls, each treatment having three or four replicates.We predicted that periphyton biomass and insect consumers would increase as buffer width decreased, because of increased solar flux. We used two complementary studies to test this prediction.In one study, we compared benthic communities before and after logging in all 13 streams; a second study focused on periphyton and insect colonization dynamics over 6‐week periods in each of four seasons in four streams, one in each treatment.Photosynthetically active radiation, and mean and maximum water temperature, increased as buffer width narrowed.Periphyton biomass, periphyton inorganic mass and Chironomidae abundance also increased as buffer width narrowed, with the largest differences occurring in the clear‐cut and 10‐m buffer treatments.Photosynthetically active radiation, water temperature, periphyton biomass and periphyton inorganic mass were significantly greater in the 30‐m buffer treatment than in controls during some seasons.Synthesis and applications.We have shown that a gradient of riparian buffer widths created a gradient in light and temperature that led to non‐linear increases in periphyton biomass and insect abundance. For example, Chironomidae abundance was generally greater in the 10‐m and 30‐m buffer treatments than in controls, whereas this was not always the case in the clear‐cut treatment. This pattern may be due to the high sediment content of the periphyton mat in the clear‐cut treatment, which potentially limited the response of some insects to increased food resources. Overall, our results indicate that uncut riparian buffers of 30‐m or more on both sides of the stream were needed to limit biotic and abiotic changes associated with clear‐cut logging in headwater, forested watersheds.
Bat activity and species richness on organic and conventional farms: impact of agricultural intensification
Authors: Wickramasinghe Liat P. , Harris Stephen , Jones Gareth , Vaughan Nancy 
Published: December 2003

Summary

Agricultural intensification is perceived to be a major cause of the decline in many European bat populations. Because organic farming prohibits the use of agrochemicals, we compared organic vs. conventional farm types to test the hypothesis that agricultural intensification based on high levels of agrochemical use has been a factor in bat population declines. Bat activity and species richness were compared on matched pairs of organic and conventional farms.
Bat activity was quantified using acoustic surveys within specific habitats on farms in southern England and Wales. Eighty‐nine per cent of bat passes were identified to species level using artificial neural networks (ANN). A further 9% were identified to genus.
Total bat activity was significantly higher on organic farms than on conventional farms. Significantly more bat passes were recorded over water on organic farms than on conventional farms. Foraging activity (quantified in two ways: total feedings buzzes and feeding buzzes per pass) was significantly higher on organic farms than on conventional farms.
The dominant species on both farm types were Pipistrellus pipistrellus and Pipistrellus pygmaeus. Significantly more passes of Myotis species were recorded on organic farms than on conventional farms. This difference was also significant when water habitats were considered alone.
The activity of both Myotis daubentonii and Myotis brandtii was significantly higher on organic farms than on conventional farms. The activity of Myotis bechsteinii and Myotis brandtii was significantly higher over organic water habitats than over conventional water habitats. Rhinolophus hipposideros and Rhinolophus ferrumequinum were only recorded on organic farms in wooded, arable and pasture habitats.
Synthesis and applications. This study highlights the position of bats as bioindicators and victims of agricultural change. The differences in bat activity between farm types may reflect features such as taller hedgerows and better water quality on organic farms. Higher foraging activity also suggests that habitat quality in terms of prey availability is greater on organic farms. Less intensive farming benefits bats, and as the number of organic enterprises increases it may help to reverse declines in bat populations.
The joint effects of larval density and 14C‐cypermethrin on the life history and population growth rate of the midge Chironomus riparius
Authors: Hooper Helen L. , Sibly Richard M. , Maund Steve J. , Hutchinson Thomas H. 
Published: December 2003

Summary

Chemical effects on organisms are typically assessed using individual‐level endpoints or sometimes population growth rate (PGR), but such measurements are generally made at low population densities. In contrast most natural populations are subject to density dependence and fluctuate around the environmental carrying capacity as a result of individual competition for resources. As ecotoxicology aims to make reliable population projections of chemical impacts in the field, an understanding of how high‐density or resource‐limited populations respond to environmental chemicals is essential.
Our objective was to determine the joint effects of population density and chemical stress on the life history and PGR of an important ecotoxicological indicator species, Chironomus riparius, under controlled laboratory conditions. Populations were fed the same ration but initiated at different densities and exposed to a solvent control and three concentrations of 14C‐cypermethrin in a sediment–water test system for 67 days at 20 ± 1 °C.
Density had a negative effect on all the measured life‐history traits, and PGR declined with increasing density in the controls. Exposure to 14C‐cypermethrin had a direct negative effect on juvenile survival, presumably within the first 24 h because the chemical rapidly dissipated from the water column. Reductions in the initial larval densities resulted in an increase in the available resources for the survivors. Subsequently, exposed populations emerged sooner and started producing offspring earlier than the controls. 14C‐cypermethrin had no effect on estimated fecundity and adult body weight but interacted with density to reduce the time to first emergence and first reproduction. As a result, PGR increased with cypermethrin concentration when populations were initiated at high densities.
Synthesis and applications. The results showed that the effects of 14C‐cypermethrin were buffered at high density, so that the joint effects of density and chemical stress on PGR were less than additive. Low levels of chemical stressors may increase carrying capacity by reducing juvenile competition for resources. More and perhaps fitter adults may be produced, similar to the effects of predators and culling; however, toxicant exposure may result in survivors that are less tolerant to changing conditions. If less than additive effects are typical in the field, standard regulatory tests carried out at low density may overestimate the effects of environmental chemicals. Further studies over a wide range of chemical stressors and organisms with contrasting life histories are needed to make general recommendations.