bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gene flow and genetic structure of the aquatic macrophyte Sparganium emersum in a linear unidirectional river
Authors: POLLUX B. J. A. , LUTEIJN A. , VAN GROENENDAEL J. M. , OUBORG N. J. 
Published: September 2008

Summary1. River systems offer special environments for the dispersal of aquatic plants because of the unidirectional (downstream) flow and linear arrangement of suitable habitats.2. To examine the effect of this flow on microevolutionary processes in the unbranched bur‐reed (Sparganium emersum) we studied the genetic variation within and among nine (sub)populations along a 103 km stretch of the Niers River (Germany–The Netherlands), using amplified fragment length polymorphisms.3. Genetic diversity in S. emersum populations increased significantly downstream, suggesting an effect of flow on the pattern of intrapopulation genetic diversity.4. Gene flow in the Niers River is asymmetrically bidirectional, with gene flow being approximately 3.5 times higher in a downstream direction. The observed asymmetry is probably caused by frequent hydrochoric dispersal towards downstream locations on the one hand, and sporadic zoochoric dispersal in an upstream direction on the other. The spread of vegetative propagules (leaf and stem fragments) is probably not an important mode of dispersal for S. emersum, suggesting that gene flow is mainly via seed dispersal. Realized dispersal distances exceeded 60 km, revealing a potential for long‐distance dispersal in S. emersum.5. There was no correlation between geographical and genetic distances among the nine S. emersum populations (i.e. no isolation by distance), which may be due to the occurrence of long‐distance dispersal and/or colonization and extinction dynamics in the Niers River.6. Overall, the genetic population structure and regional dispersal patterns of S. emersum in the Niers River are best explained by a linear metapopulation model. Our study shows that flow can exert a strong influence on population genetic processes of plants inhabiting stream systems.
Retinoic acid inhibits in vivo interleukin‐2 gene expression and T‐cell activation in mice
Authors: Ertesvag Aase , Austenaa Liv M. I. , Carlsen Harald , Blomhoff Rune , Blomhoff Heidi Kiil 
Published: September 2008

SummaryInterleukin‐2 (IL‐2) is an essential cytokine for T‐lymphocyte homeostasis. We have previously reported that all‐trans retinoic acid (atRA) enhances the secretion of IL‐2 from human peripheral blood T cells in vitro, followed by increased proliferation and inhibition of spontaneous cell death. In this study we used a transgenic IL‐2 gene luciferase reporter model to examine the effects of atRA in vivo. In contrast to the observations in human T cells, we found an overall reduction in luciferase‐reported IL‐2 gene expression in mice treated with atRA. Whole‐body luminescence of anti‐CD3‐treated and non‐treated mice was reduced in mice receiving atRA. Accordingly, after 7 hr, IL‐2 gene expression was on average 55% lower in the atRA‐treated mice compared with the control mice. Furthermore, mice fed a vitamin A‐deficient diet had a significantly higher basal level of luciferase activity compared with control mice, demonstrating that vitamin A modulates IL‐2 gene expression in vivo. Importantly, the atRA‐mediated inhibition of IL‐2 gene expression was accompanied by decreased DNA synthesis in murine T cells, suggesting a physiological relevance of the reduced IL‐2 gene expression observed in transgenic reporter mice.
Increased secretion of hyperimmune antibodies following lipopolysaccharide stimulation of CD40‐activated human B cells in vitro
Authors: Dumont Nellie , Aubin Eric , Proulx Dominic P. , Lemieux Réal , Bazin Renée 
Published: September 2008

SummaryHuman B cells can be cultured ex vivo for a few weeks, following stimulation of the CD40 cell surface molecule in the presence of recombinant cytokines such as interleukin‐4 (IL‐4). However, attempts to produce polyclonal antigen‐specific human antibodies by in vitro culture of human B cells obtained from immunized donors have not been successful. It has been shown in mice that lipopolysaccharide (LPS) is a potent mitogen for B cells and plays an important role in the generation of antigen‐specific antibody responses. Although it has long been believed that LPS has no direct effect on human B cells, recent data indicating that IL‐4‐activated human B cells are induced to express Toll‐like receptor‐4, the main LPS receptor, prompted us to study the effects of LPS on the proliferation and antibody secretion of human B cells. Our results showed that LPS caused a reduction in the expansion of CD40‐activated human B cells, accompanied by an increase in antigen‐specific antibody secretion. This result suggested that some, but not all, B cells were able to differentiate into antibody‐secreting cells in response to LPS. This increased differentiation could be explained by the observation that LPS‐stimulated human B cells were induced to secrete higher amounts of IL‐6, a pleiotropic cytokine well‐known for its B‐cell differentiation activity. In vivo, the effect of LPS on cytokine secretion by B cells may not only enhance B‐cell differentiation but also help to sustain a local ongoing immune response to invading Gram‐negative bacteria, until all pathogens have been cleared from the organism.
Dendritic cells: a family portrait at mid‐gestation
Authors: Bizargity Peyman , Bonney Elizabeth A. 
Published: September 2008

SummaryRecent advances in our understanding of dendritic cells (DCs) and their role in tolerance and immunity has fuelled study of their normal development and function within the reproductive tract. The common hypothesis that pregnancy is a state of immune suppression or deviation now includes the idea that alterations in DC phenotype and function are critical for maternal tolerance. We chose to study DCs in the uterus and lymphoid tissue in non‐pregnant and pregnant mice at mid‐gestation to understand what DC‐related factors may be involved in premature birth. We used a mouse model where the mother’s immune system has been shown to respond to the male antigen H‐Y. Observed differences among DCs in the uterus, uterine draining nodes and spleen, even in non‐pregnant mice, suggest the existence of a specialized uterus‐specific subset of DCs. We further found that, amongst CD45+ CD11c+ cells in the uterus and peripheral lymphoid tissue of pregnant mice, expression of major histocompatibility complex class II (MHC II) and costimulatory molecules (i.e. CD80) was similar to that in the non‐pregnant state. Moreover, there was no pregnancy‐related decrease in the proportion of CD11c+ cells in the uterus or in the uterine node that were CD11b− CD8+. Pregnancy increased the CD11b+ subsets and the expression of chemokine (C‐C motif) ligand 6 (CCL6) in DCs of the uterine draining nodes. Finally, DC subsets showed variable expression, with respect to tissue and pregnancy, of the cytokine interleukin‐15, which is important in lymphoid cell homeostasis. For DCs, pregnancy is not a state of immune paralysis, but of dynamic developmental change.
Poly(ADP‐ribose) polymerase‐1 (Parp‐1)‐deficient mice demonstrate abnormal antibody responses
Authors: Ambrose Helen E. , Willimott Shaun , Beswick Richard W. , Dantzer Françoise , De Murcia Josiane Ménissier , Yelamos José , Wagner Simon D. 
Published: September 2008

SummaryPoly(ADP‐ribosylation) of acceptor proteins is an epigenetic modification involved in DNA strand break repair, recombination and transcription. Here we provide evidence for the involvement of poly(ADP‐ribose) polymerase‐1 (Parp‐1) in antibody responses. Parp‐1−/− mice had increased numbers of T cells and normal numbers of total B cells. Marginal zone B cells were mildly reduced in number, and numbers of follicular B cells were preserved. There were abnormal levels of basal immunoglobulins, with reduced levels of immunoglobulin G2a (IgG2a) and increased levels of IgA and IgG2b. Analysis of specific antibody responses showed that T cell‐independent responses were normal but T cell‐dependent responses were markedly reduced. Germinal centres were normal in size and number. In vitro purified B cells from Parp‐1−/− mice proliferated normally and showed normal IgM secretion, decreased switching to IgG2a but increased IgA secretion. Collectively our results demonstrate that Parp‐1 has essential roles in normal T cell‐dependent antibody responses and the regulation of isotype expression. We speculate that Parp‐1 forms a component of the protein complex involved in resolving the DNA double‐strand breaks that occur during class switch recombination.
Anti‐ribosomal phosphoprotein autoantibody triggers interleukin‐10 overproduction via phosphatidylinositol 3‐kinase‐dependent signalling pathways in lipopolysaccharide‐activated macrophages
Authors: Lee Tai‐Ping , Leu Shr‐Jeng Jim , Huang Jason C. , Song Ying‐Chyi , Jhou Ren‐Shiang , Tang Shye‐Jye , Sun Kuang‐Hui 
Published: September 2008

SummaryAnti‐ribosomal phosphoprotein autoantibodies have been shown to be significantly associated with multiple manifestations of systemic lupus erythematosus (SLE). High levels of interleukin‐10 (IL‐10) have been demonstrated to contribute to lupus susceptibility and severity. In this study, we investigated the molecular mechanisms of anti‐ribosomal phosphoprotein monoclonal antibody (anti‐P mAb)‐induced autoimmune responses. Anti‐P mAb promoted IL‐10 overproduction in a dose‐ and time‐dependent manner in both lipopolysaccharide (LPS)‐activated RAW 264.7 cells and primary human macrophages. Anti‐P mAb enhanced phosphorylation of Akt (PKB; protein kinase B), extracellular signal regulated kinase 1/2 (ERK1/2) and c‐Jun NH2‐terminal kinase 1/2 (JNK1/2), while phosphorylation of p38 remained unaltered. Furthermore, anti‐P mAb decreased glycogen synthase kinase 3 (GSK3) activity and reduced the phosphorylation of IκBα in LPS‐activated macrophages. The Syk, phosphatidylinositol 3‐kinase (PI3K), protein kinase C (PKC), JNK and ERK signalling pathways involved in anti‐P mAb‐triggered IL‐10 secretion were also confirmed using various pharmacological inhibitors. In addition, nuclear factor (NF)‐κB had negative regulatory effects on anti‐P mAb‐triggered IL‐10 secretion. Using reporter plasmids containing the nuclear factor binding sites of NF‐κB, cAMP‐enhanced activation protein 1 (AP‐1), serum response element (SRE) or cyclic AMP response element (CRE), treatment of anti‐P mAb led to activation of the corresponding factors that bind to the AP‐1 site, SRE and CRE in the LPS‐activated macrophages. Furthermore, by transfection with reporter plasmids bearing various lengths of the IL‐10 promoter, the AP‐1 binding site, SRE and CRE were shown to be required for anti‐P mAb‐induced effects. Collectively, our results provide a molecular model for anti‐P mAb‐induced IL‐10 overproduction in LPS‐activated macrophages, which may play a role in the pathogenesis of SLE.
Expansion of CD4+ CD25+ Foxp3+ T cells by bone marrow‐derived dendritic cells
Authors: Marguti Ivo , Yamamoto Guilherme Lopes , da Costa Thaís Boccia , Rizzo Luiz Vicente , de Moraes Luciana Vieira 
Published: September 2008

SummaryDendritic cells (DCs) are the most important antigen‐presenting cells of the immune system and have a crucial role in T‐lymphocyte activation and adaptive immunity initiation. However, DCs have also been implicated in maintaining immunological tolerance. In this study, we evaluated changes in the CD4+ CD25+ Foxp3+ T‐cell population after co‐culture of lymph node cells from BALB/c mice with syngeneic bone marrow‐derived DCs. Our results showed an increase in CD4+ CD25+ Foxp3+ T cells after co‐culture which occurred regardless of the activation state of DCs and the presence of allogeneic apoptotic cells; however, it was greater when DCs were immature and were pulsed with the alloantigen. Interestingly, syngeneic apoptotic thymocytes were not as efficient as allogeneic apoptotic cells in expanding the CD4+ CD25+ Foxp3+ T‐cell population. In all experimental settings, DCs produced high amounts of transforming growth factor (TGF)‐β. The presence of allogeneic apoptotic cells induced interleukin (IL)‐2 production in immature and mature DC cultures. This cytokine was also detected in the supernatants under all experimental conditions and enhanced when immature DCs were pulsed with the alloantigen. CD4+ CD25+ Foxp3+ T‐cell expansion during co‐culture of lymph node cells with DCs strongly suggested that the presence of alloantigen enhanced the number of regulatory T cells (Tregs) in vitro. Our data also suggest a role for both TGF‐β and IL‐2 in the augmentation of the CD4+ CD25+ Foxp3+ population.
Using expert knowledge to assess uncertainties in future polar bear populations under climate change
Authors: O’Neill Saffron J. , Osborn Tim J. , Hulme Mike , Lorenzoni Irene , Watkinson Andrew R. 
Published: September 2008

Summary

Polar bear Ursus maritimus population dynamics under conditions of climate change has become a controversial topic. A survey of expert opinion based on modelled sea‐ice data was performed in order to quantify the trends and variance surrounding possible impacts of climate change on polar bear populations.
Polar bears have become an iconic species in the communication of climate change. Negative impacts of climatic warming on polar bears have been suggested, but cannot be fully quantified as no Arctic‐wide models yet exist to analyse the relationship between polar bear population dynamics and climate change.
Ten polar bear experts participated in an expert opinion survey in early 2007, quantifying the trends and variance surrounding possible impacts of climate change on polar bear populations. The experts were provided with maps and time‐series of sea‐ice extent and duration to 2050, simulated under a mid‐range emissions scenario. Expert projections of future polar bear habitat range and population size across the Arctic, and for population size in five regions, were obtained. Experts were asked to define ‘best conservation practice’, and to re‐evaluate the total Arctic population projection if this best practice was implemented.
Most experts project a substantial decline in polar bear range and population size across the Arctic and in population size across each region. Expert best estimates for total Arctic polar bear population size lie from no change to a 70% decrease by 2050 relative to today; with half the experts projecting at least a 30% decrease. The median best estimates show the Barents Sea, Hudson Bay and the Chukchi Sea populations experiencing the greatest population decline under this scenario. There is much uncertainty both within and between expert responses, especially in little‐researched regions such as the Chukchi Sea.
Synthesis and applications. Based on projected changes in sea‐ice extent, experts suggest that polar bear populations will undergo significant declines by 2050, even implementing best management practices, under the scenario of climatic warming outlined here. The expert survey approach could be applied to a wide range of species for which there is a lack of available data and considerable uncertainty surrounding all aspects of the problem that prevent quantification with more formal modelling approaches.
Two short‐chain dehydrogenase/reductases, NON‐YELLOW COLORING 1 and NYC1‐LIKE, are required for chlorophyll b and light‐harvesting complex II degradation during senescence in rice
Authors: Sato Yutaka , Morita Ryouhei , Katsuma Susumu , Nishimura Minoru , Tanaka Ayumi , Kusaba Makoto 
Published: September 2008

SummaryYellowing, which is related to the degradation of chlorophyll and chlorophyll–protein complexes, is a notable phenomenon during leaf senescence. NON‐YELLOW COLORING1 (NYC1) in rice encodes a membrane‐localized short‐chain dehydrogenase/reductase (SDR) that is thought to represent a chlorophyll b reductase necessary for catalyzing the first step of chlorophyll b degradation. Analysis of the nyc1 mutant, which shows the stay‐green phenotype, revealed that chlorophyll b degradation is required for the degradation of light‐harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1‐LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay‐green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of chlorophyll b was severely inhibited and light‐harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol double mutant did not show prominent enhancement of inhibition of chlorophyll degradation. NOL was localized on the stromal side of the thylakoid membrane despite the lack of a transmembrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These observations suggest that NOL and NYC1 are co‐localized in the thylakoid membrane and act in the form of a complex as a chlorophyll b reductase in rice.
The Regai Dzive Shiri Project: a cluster randomised controlled trial to determine the effectiveness of a multi‐component community‐based HIV prevention intervention for rural youth in Zimbabwe – study design and baseline results
Authors: Cowan Frances M. , Pascoe Sophie J. S. , Langhaug Lisa F. , Dirawo Jeffrey , Chidiya Samson , Jaffar Shabbar , Mbizvo Michael , Stephenson Judith M. , Johnson Anne M. , Power Robert M. , Woelk Godfrey , Hayes Richard J. 
Published: September 2008

SummaryObjective  To assess the effectiveness of a community‐based HIV prevention intervention for adolescents in terms of its impact on (1) HIV and Herpes simplex virus type 2 (HSV‐2) incidence and on rates of unintended pregnancy and (2) reported sexual behaviour, knowledge and attitudes.Methods  Cluster randomised trial of a multi‐component HIV prevention intervention for adolescents based in rural Zimbabwe. Thirty communities were selected and randomised in 2003 to early or deferred intervention implementation. A baseline bio‐behavioural survey was conducted among 6791 secondary school pupils (86% of eligibles) prior to intervention implementation.Results  Baseline prevalences were 0.8% (95% CI: 0.6–1.0) for HIV and 0.2% (95% CI: 0.1–0.3%) for HSV‐2. Four girls (0.12%) were pregnant. There was excellent balance between study arms. Orphans who made up 35% of the cohort were at increased risk of HIV [age–sex adjusted odds ratio 3.4 (95% CI: 1.7–6.5)]. 11.9% of young men and 2.9% of young women reported that they were sexually active (P < 0.001); however, there were inconsistencies in the sexual behaviour data. Girls were less likely to know about reproductive health issues than boys (P < 0.001) and were less likely to have used and to be able to access condoms (P < 0.001).Conclusion  This is one of the first rigorous evaluations of a community‐based HIV prevention intervention for young people in southern Africa. The low rates of HIV suggest that the intervention was started before this population became sexually active. Inconsistency and under‐reporting of sexual behaviour re‐emphasise the importance of using externally validated measures of sexual risk reduction in behavioural intervention studies.
Expression of major histocompatibility complex class I proteins and their antigen processing chaperones in mouse embryonic stem cells from fertilized and parthenogenetic embryos
Authors: Lampton P. W. , Crooker R. J. , Newmark J. A. , Warner C. M. 
Published: September 2008

AbstractEmbryonic stem (ES) cells are pluripotent cells with the potential to differentiate into cells or tissues that may be used for transplantation therapy. Parthenogenetic ES (pES) cells have been recently derived from both mouse and human oocytes and hold promise as a cell source that is histocompatible to the oocyte donor. Because of the importance of major histocompatibility complex (MHC) antigens in mediating tissue rejection or acceptance, we examined levels of mRNA and protein expression of MHC class I proteins, as well as several MHC class I antigen processing and presentation chaperones in mouse ES cells derived from both fertilized (fES) and parthenogenetic (pES) embryos. We found that H‐2K, Qa‐2, TAP1, TAP2, and tapasin mRNAs were all expressed at low levels in undifferentiated and differentiating ES cells and were significantly upregulated in response to interferon‐γ (IFN‐γ) treatment following 14 days of differentiation. Likewise, expression of H‐2Kb and H‐2Kk proteins were upregulated to detectable levels by IFN‐γ after 14 days of differentiation, but Qa‐2 protein expression remained low or absent. We also found that MHC class I, TAP1, TAP2, and tapasin mRNAs were all expressed at very low levels in ES cells compared with T cells, suggesting transcriptional regulation of these genes in ES cells. Calnexin, a chaperone molecule involved in other pathways than MHC expression, had mRNA levels that were similar in ES cells and T cells and was not upregulated by IFN‐γ in ES cells. Overall, ES cells derived from fertilized embryos and parthenogenetic embryos displayed remarkably similar patterns of gene expression at the mRNA and protein levels. The similarity between the fES and pES cell lines with regard to expression of MHC class I and antigen‐processing machinery provides evidence for the potential usefulness of pES cells in transplantation therapy.
Monitoring and dispersal of the invading GracillariidaeCameraria ohridella
Authors: Augustin S. , Guichard S. , Heitland W. , Freise J. , Svatoš A. , Gilbert M. 
Published: September 2008

AbstractThe horse‐chestnut leafminerCameraria ohridellais an invasive lepidoptera (Gracillariidae) which has spread throughout Europe over the last two decades. The species can be detected easily because of its noticeable damage to horse‐chestnut trees leaves, which allows the easy collection of large‐scale monitoring data. It is therefore an interesting model species to study invasion processes, and this review summarizes recent progresses in that regard. The date reported here result from monitoring ofC. ohridellapopulation based on pheromone traps and visual observation of damage carried out in Belgium, France, Germany, Switzerland and the UK. The patterns of spread measured using these different monitoring method, and the key factors associated with short‐distance dispersal (within cities), and large‐scale dispersal (across landscapes) are presented and discussed.
CONTRAST‐FREE BALLOON‐ASSISTED UNILATERAL PLASTIC STENTING IN MALIGNANT HILAR BILIARY OBSTRUCTION: A NEW METHOD
Authors: Singh Virendra , Singh Gurpreet , Verma Ganga Ram , Gupta Vikash , Gupta Rajesh , Kapoor Rakesh , Sharma Navneet , Bhalla Ashish 
Published: September 2008

Background:  Unilateral endoscopic drainage in unresectable type II malignant hilar biliary obstruction is effective. Contrast injection leads to cholangitis. Recently, contrast‐free unilateral metal stenting in malignant hilar biliary obstruction has shown encouraging results, however, it is costly.Methods:  We prospectively studied the outcome of unilateral balloon‐assisted plastic stenting in 15 patients with type II malignant hilar biliary obstruction without contrast.Results:  A successful endoscopic drainage was achieved in 100% (15/15) patients. Cholangitis occurred in none and no patient died within 30 days. Mean patency of stent was 104.8 ± 18.3 days. Mean (±SD) survival of these patients was 129.5 ± 39.2 days. No major complications were observed.Conclusions:  Unilateral endoscopic contrast‐free balloon‐assisted plastic stenting in type II malignant hilar biliary obstruction is a safe and effective method of palliation. However, a larger study is needed to validate the findings.