bluuebunny/crossref_metadata_2025_split huggingface dataset:
Platelet endothelial cell adhesion molecule‐1 and mechanotransduction in vascular endothelial cells
Authors: FUJIWARA K. 
Published: February 2006

Abstract.Endothelial cells are known to respond to mechanical forces such as fluid shear stress and cyclic stretch, but elucidating the mechanism for mechanosensing has been difficult. Experimental data indicate that there are probably several sensing mechanisms. We have recently proposed a novel mechanoresponse mechanism that involves platelet endothelial cell adhesion molecule‐1 (PECAM‐1). When endothelial cells are stimulated by fluid shear stress, PECAM‐1 is tyrosine phosphorylated and activates the extracellular signal‐regulated kinase 1 and 2 (ERK1/2) signalling cascade. The same signalling events occurred when we applied pulling force directly on PECAM‐1 on the endothelial cell surface using magnetic beads coated with antibodies against the external domain of PECAM‐1. These results appear to indicate that PECAM‐1 is a mechanotransduction molecule. To our knowledge, this is the first mammalian molecule that is shown to respond to mechanical force directly exerted to it.
Secretins take shape
Authors: Bayan Nicolas , Guilvout Ingrid , Pugsley Anthony P. 
Published: February 2006

SummarySecretins are a unique class of bacterial multimeric outer membrane proteins that probably differ considerably from other, less complex outer membrane proteins in their overall structure and organization, and in their requirements for outer membrane targeting and assembly factors. In this MicroCommentary, we discuss these differences with respect to the role of a specific class of lipoproteins, often referred to as pilotins, in secretin complex assembly. We compare them with other lipoproteins that play a role in Omp85/YaeT‐mediated assembly of more classical outer membrane proteins. One of the examples we have chosen is the Myxococcus Xanthus lipoprotein Tgl. Coculture of cells with and without Tgl allows secretin assembly (and, hence, type IV pilus assembly) in the cells without Tgl, indicating that it can act by cell‐to‐cell contact or can transfer between cells.
Cholera stool bacteria repress chemotaxis to increase infectivity
Authors: Butler Susan M. , Nelson Eric J. , Chowdhury Nityananda , Faruque Shah M. , Calderwood Stephen B. , Camilli Andrew 
Published: February 2006

SummaryFactors that enhance the transmission of pathogens are poorly understood. We show that Vibrio cholerae shed in human ‘rice‐water’ stools have a 10‐fold lower oral infectious dose in an animal model than in vitro grown V. cholerae, which may aid in transmission during outbreaks. Furthermore, we identify a bacterial factor contributing to this enhanced infectivity: The achievement of a transient motile but chemotaxis‐defective state upon shedding from humans. Rice‐water stool V. cholerae have reduced levels of CheW‐1, which is essential for chemotaxis, and were consequently shown to have a chemotaxis defect when tested in capillary assays. Through mutational analyses, such a state is known to enhance the infectivity of V. cholerae. This is the first report of a pathogen altering its chemotactic state in response to human infection in order to enhance its transmission.
The Mycobacterium tuberculosis PhoPR two‐component system regulates genes essential for virulence and complex lipid biosynthesis
Authors: Walters Shaun B. , Dubnau Eugenie , Kolesnikova Irina , Laval Francoise , Daffe Mamadou , Smith Issar 
Published: February 2006

SummaryTwo‐component signal transduction systems (2‐CS) play an important role in bacterial pathogenesis. In the work presented here, we have studied the effects of a mutation in the Mycobacterium tuberculosis (Mtb) PhoPR 2‐CS on the pathogenicity, physiology and global gene expression of this bacterial pathogen. Disruption of PhoPR causes a marked attenuation of growth in macrophages and mice and prevents growth in low‐Mg2+ media. The inability to grow in THP‐1 macrophages can be partially overcome by the addition of excess Mg2+ during infection. Global transcription assays demonstrate PhoP is a positive transcriptional regulator of several genes, but do not support the hypothesis that the Mtb PhoPR system is sensing Mg2+ starvation, as is the case with the Salmonella typhimurium PhoPQ 2‐CS. The genes that were positively regulated include those found in the pks2 and the msl3 gene clusters that encode enzymes for the biosynthesis of sulphatides and diacyltrehalose and polyacyltrehalose respectively. Complementary biochemical studies, in agreement with recent results from another group, indicate that these complex lipids are also absent from the phoP mutant, and the lack of these components in its cell envelope may indirectly cause the mutant's high‐Mg2+ growth requirement. The experiments reported here provide functional evidence for the PhoPR 2‐CS involvement in Mtb pathogenesis, and they suggest that a major reason for the attenuation observed in the phoP mutant is the absence of certain complex lipids that are known to be important for virulence.
The effect of drought on C and N stable isotopes in different fractions of leaves, stems and roots of sensitive and tolerant beech ecotypes
Authors: PEUKE A. D. , GESSLER A. , RENNENBERG H. 
Published: February 2006

ABSTRACTBeech seedlings from 11 German climatic provenances were exposed to a realistically timed drought treatment in a greenhouse experiment. The stable isotope composition of carbon (C) and nitrogen (N) was analysed in pooled bulk material of roots, stems and leaves, as well as in the aqueous extracts and starch fractions. The δ13C values increased in bulk samples (BS) of roots, stems and leaves by drought, although no leaf growth occurred during the experimental period. A clear drought effect on δ13C in aqueous extracts was detected in leaves. In aqueous extracts of stems and roots as well as in starch fractions of all organs, abundance of δ13C also tended to be increased by drought, but this effect was not statistically significant. For both δ13C and δ15N, enrichment was observed from the site of uptake/source to the site of use/sink. A gradient for δ13C in all fractions from leaves (−29.49, −28.89 and −27.85‰) to stems (−28.81, −27.48 and −26.98‰) and to roots (−27.60, −26.37 and −26.48‰) was detected in BS, aqueous extracts and starch, respectively. An opposite gradient for δ15N was found in BS: 1.59‰, 1.84‰ and 3.05‰ in roots, stems and leaves, respectively. δ15N was neither affected by drought in the BS nor in aqueous extracts, but an effect of provenance was observed. Particularly in roots and stems, drought‐sensitive provenances showed the strongest shifts in δ13C induced by drought and the lowest δ15N values. In the present experiment, δ13C values were more affected by the environmental factor drought, while δ15N values were more affected by the genetic factor provenance.
Sugar and ABA response pathways and the control of gene expression
Authors: ROOK FRED , HADINGHAM SOPHIE A. , LI YUNHAI , BEVAN MICHAEL W. 
Published: February 2006

ABSTRACTSugars are essential to plant growth and metabolism, both as energy source and as structural components. Sugar production and use are in part controlled at the level of gene expression by the sugars themselves. Responses to sugar are closely integrated with response pathways that indicate environmental conditions such as light and water availability. High sugar levels inhibit seedling development, repress photosynthetic gene expression and induce genes of storage metabolism such as those of starch biosynthesis. Genetic approaches have demonstrated the importance of abscisic acid (ABA) and the transcriptional regulator ABA‐insensitive4 (ABI4) in sugar response pathways. Recent analysis of both photosynthetic and starch biosynthetic gene promoters suggest a direct role for ABI4 in their control. The increased understanding of the regulatory promoter elements controlling gene expression, in response to sugar and ABA, allows transcriptional networks to be understood at a molecular level.
The hydraulic limitation hypothesis revisited
Authors: RYAN MICHAEL G. , PHILLIPS NATHAN , BOND BARBARA J. 
Published: February 2006

ABSTRACTWe proposed the hydraulic limitation hypothesis (HLH) as a mechanism to explain universal patterns in tree height, and tree and stand biomass growth: height growth slows down as trees grow taller, maximum height is lower for trees of the same species on resource‐poor sites and annual wood production declines after canopy closure for even‐aged forests. Our review of 51 studies that measured one or more of the components necessary for testing the hypothesis showed that taller trees differ physiologically from shorter, younger trees. Stomatal conductance to water vapour (gs), photosynthesis (A) and leaf‐specific hydraulic conductance (KL) are often, but not always, lower in taller trees. Additionally, leaf mass per area is often greater in taller trees, and leaf area:sapwood area ratio changes with tree height. We conclude that hydraulic limitation of gas exchange with increasing tree size is common, but not universal. Where hydraulic limitations toAdo occur, no evidence supports the original expectation that hydraulic limitation of carbon assimilation is sufficient to explain observed declines in wood production. Any limit to height or height growth does not appear to be related to the so‐called age‐related decline in wood production of forests after canopy closure. Future work on this problem should explicitly link leaf or canopy gas exchange with tree and stand growth, and consider a more fundamental assumption: whether tree biomass growth is limited by carbon availability.
Comparative transcriptome analysis of toxic metal responses inArabidopsis thalianaand the Cd2+‐hypertolerant facultative metallophyteArabidopsis halleri
Authors: WEBER MICHAEL , TRAMPCZYNSKA ALEKSANDRA , CLEMENS STEPHAN 
Published: February 2006

ABSTRACTToxic effects of both essential and non‐essential heavy metals are well documented in plants. Very little is known, however, about their modes of toxicity, about tolerance mechanisms and the signalling cascades involved in mediating transcriptional responses to toxic metal excess. We analysed transcriptome changes upon Cd2+and Cu2+exposure in roots ofArabidopsis thalianaand the Cd2+‐hypertolerant metallophyteArabidopsis halleri. Particularly, three categories of genes were identified with the help of this comparative approach: (1) common responses, which might indicate stable and functionally relevant changes conserved across plant species; (2) metallophyte‐specific responses as well as transcripts differentially regulated between the two species, representing candidate genes for Cd2+hypertolerance; and (3) those specifically responsive to Cd2+and therefore indicative of toxicity mechanisms or potentially involved in signalling cascades. Our data define, for instance,Arabidopsiscore responses to Cd2+and Cu2+. In addition, they suggest that Cd2+exposure very rapidly results in apparent Zn deficiency, and they show the existence of highly specific Cd2+responses and distinct signalling cascades. Array results were independently confirmed by real‐time quantitative PCR, thereby further validating cross‐species transcriptome analysis with oligonucleotide microarrays.
Autocrine Type I Interferon Amplifies Dendritic Cell Responses to Lipopolysaccharide via the Nuclear Factor‐κB/p38 Pathways
Authors: Pollara G. , Handley M. E. , Kwan A. , Chain B. M. , Katz D. R. 
Published: February 2006

AbstractThe central role of dendritic cells (DC) in the initiation of immune responses requires these cells to be able to determine the degree of danger in their microenvironment. Abrogating the activity of type I interferon (IFN) secreted after lipopolysaccharide (LPS) stimulation of DC inhibits CD86 and human leucocyte antigen‐DR (HLA‐DR) upregulation at a low LPS concentration. At a higher concentration of LPS, while changes in surface phenotype are not dependent on type I IFN, this cytokine is required for maximal secretion of interleukin‐12 (IL‐12) and tumour necrosis factor‐α (TNFα) by DC. Thus, the secretion and autocrine activity of type I IFN after Toll‐like receptor stimulation enables DC to orchestrate a hierarchical maturation response with regard to changes in surface phenotype and secretion of cytokines. In addition, the activation of nuclear factor‐κB and p38 pathways in DC can occur either in an additive fashion when DC are exposed to dual stimulation or can be activated in discrete phases over time when DC are exposed to LPS alone. The differential activation of these pathways provides a mechanism for DC to integrate the activation by multiple stimuli and thus amplify responses to pathogen infection.
Oral Spray Immunization May Be an Alternative to Intranasal Vaccine Delivery to Induce Systemic Antibodies but not Nasal Mucosal or Cellular Immunity
Authors: Bakke H. , Samdal H. H. , Holst J. , Oftung F. , Haugen I. L. , Kristoffersen A.‐C. , Haugan A. , Janakova L. , Korsvold G. E. , Krogh G. , Andersen E. A. S. , Djupesland P. , Holand T. , Rappuoli R. , Haneberg B. 
Published: February 2006

AbstractSixty‐five healthy adult volunteers were immunized four times at 1‐week intervals with an inactivated whole‐virus influenza vaccine based on the strain A/New Caledonia/20/99 (H1N1) without adjuvant. The vaccine was administered as nasal spray with a newly developed device to secure intranasal delivery (OptiMist™, OptiNose AS, Oslo, Norway), as regular nasal spray, nasal drops or as an oral spray. Significant IgA‐antibody responses in nasal secretions were induced in volunteers immunized intranasally but not after oral spray immunization. In saliva, IgA antibodies were only marginally amplified even after oral spray immunizations. At least 73% of the volunteers belonging to any group of vaccine delivery reached serum haemagglutination inhibition titres of 40 or higher, considered protective against influenza, after only two vaccine doses. Those who had the vaccine delivered intranasally also showed evidence from in vitro secretion of granzyme B that cytotoxic T cells had been stimulated. Although immunization with the breath‐actuated OptiMist™ device and nasal drops were superior with respect to both mucosal and systemic immune responses, oral spray immunization might still be considered for studies of mucosal adjuvants that are not yet acceptable for intranasal use.
Sustained Interleukin‐6 and Interleukin‐8 Expression Following Infection with Chlamydia trachomatis Serovar L2 in a HeLa/THP‐1 Cell Co‐culture Model
Authors: Mpiga P. , Mansour S. , Morisset R. , Beaulieu R. , Ravaoarinoro M. 
Published: February 2006

Abstract Chlamydia trachomatis, an intracellular obligate bacterium, remains responsible for a large spectrum of disorders that can progress to chronic diseases, resulting in severe sequelae, such as tubal infertility and blindness. These sequelae may be due to deleterious immune responses induced by repeated or persistent infections. By initiating and regulating inflammation as well as immune responses, pro‐inflammatory cytokines secreted by local infected epithelial and immune cells, such as monocytes, may play an essential role in immunity and in the immunopathogenesis of chlamydial diseases. In this study, we mimicked the in vivo interaction between epithelial cells and monocytes by co‐culturing epithelial‐like HeLa cells with monocyte‐like THP‐1 cells. Pro‐inflammatory cytokines [interleukin‐β (IL‐1β), IL‐6, IL‐8, IL‐10, IL‐12p70 and tumour necrosis factor‐α (TNF‐α)] were measured by multiplexed cytometric bead array assay over a period of 18 days. We observed that pro‐inflammatory cytokine secretion was augmented after C. trachomatis infection in HeLa and THP‐1 cells. However, this heightened secretion was subsequently reduced. When infected HeLa cells were co‐cultured with THP‐1 cells, IL‐6 and IL‐8 secretion was sustained, IL‐1β expression followed a bell‐shaped curve and IL‐10, IL‐12p70 and TNF‐α synthesis was downregulated. IL‐6 and IL‐8 may be involved in the immunopathogenesis of chronic chlamydial infections. We also observed that throughout C. trachomatis persistence induced by doxycycline (Dox) treatment, IL‐1β, IL‐6, IL‐8 and TNF‐α expression was reduced, whereas the synthesis of IL‐10 and IL‐12p70 remained unchanged but not sustained. Thus, during chlamydial persistence infection evoked by treatment with Dox, none of the tested cytokines showed sustained expression.
Micromorphology and geochemistry of groundwater silcretes in the eastern South Downs, UK
Authors: ULLYOTT J. STEWART , NASH DAVID J. 
Published: February 2006

AbstractGroundwater silcretes have been recognized recently as major terrestrial silicon sinks and yet their origins are poorly understood. This paper aims to further the understanding of the micro‐fabric, geochemistry and formation of groundwater silcretes, through detailed analyses of silcrete boulders from the South Downs, Sussex, UK. In‐depth petrological investigations of silcrete blocks identified three varieties of silcrete across the study area (saccharoid, hard and pebbly conglomeratic or silcrete breccia), similar to those elsewhere in England. Silcrete fabrics were universally simple and preserved host material structures. Optically continuous quartz overgrowths were the dominant cement and developed on framework grains in the absence of silt‐ and clay‐sized particles. Finer‐grained silica cements occurred in isolated patches and as vein‐ or cap‐like geopetal features. These caps and veins formed through the silicification of illuviated clay‐rich material that entered the host sediment prior to, or in the early stages of, overgrowth formation. Titanium contents were related to the amount of fine‐grained silica and appear to reflect variations in host material chemistry. Subsequent to silicification, the silcretes were altered by at least two phases of ferruginization, characterized by the ingress of iron minerals and partial fabric dissolution or replacement. The study reveals strong similarities in the micromorphology and geochemistry of groundwater silcretes in the study area and those developed in sandy host sediments in neighbouring parts of northwest Europe. Variations that do occur could be explained by differences in the host sediment, geological setting or tectonic history of the respective basins (or sub‐basins), suggesting that there may be a common mechanism for silcrete formation across north‐west Europe. Silcrete development appears to be related to the release of silica accompanying acid leaching of the host material or adjacent strata. In the South Downs, this probably resulted from oxidation of pyrite in the argillaceous and lignitic sediments overlying the host sands. It is envisaged that palaeoenvironmental conditions were of limited importance for silcrete development and that there was no specific ‘era’ of formation, with phased development accompanying landscape evolution through the Neogene into the Pleistocene.
The influence of vegetation on turbulence and flow velocities in European salt‐marshes
Authors: NEUMEIER URS , AMOS CARL L. 
Published: February 2006

AbstractFlow hindrance by salt‐marsh vegetation is manifested in the structure of the tidal current; it has a significant impact on sediment transport and it has been related to increased sediment accretion. The flow characteristics in three different vegetation types (Spartina maritima, Sp. anglica and Salicornia sp./Suaeda maritima) were measured on three salt‐marshes in Portugal and England. These in situ measurements differ from laboratory flume experiments with ‘clean’ vegetation by the complexity of natural canopies. Skimming flow develops above the Spartina canopy when the vegetation is fully submerged. In this situation, a low turbulence zone with nearly constant velocity in the denser canopy is separated from the skimming flow above by an interface characterized by high Reynolds stresses. In the low turbulence zone, a positive relationship exists between turbulence intensity and shoot density, which is due to wake turbulence generated locally in the canopy. The rate of particle settling should be increased in that zone. The lower limit of skimming flow is best predicted by the height within the canopy that includes 85% of the biomass. For emergent Spartina canopies and the short Salicornia/Suaeda marsh, the maximal velocity‐gradient is shifted upwards compared to a standard boundary layer over bare sediment and the turbulence is attenuated near the bed, but to a lesser extent than for fully submerged Spartina canopies. A turbulence reduction near the bed was observed in all measured profiles; that should enhance sediment deposition and protects the bed against subsequent erosion.
Kerion and dermatophytic granuloma. Mycological and histopathological findings in 19 children with inflammatory tinea capitis of the scalp
Authors: Arenas Roberto , Toussaint Sonia , Isa‐Isa Rafael 
Published: February 2006

AbstractBackground  Inflammatory tinea capitis or kerion is the result of a hypersensitivity reaction to a dermatophytic infection. Majocchi's granuloma, in contrast, usually begins as a suppurative folliculitis and culminates in a granulomatous reaction.Objectives  To present clinical, mycological and histopathological findings for 19 cases of kerion of the scalp in children.Methods  Nineteen children were investigated (14 boys and five girls) with a mean age of 6.5 years. A potassium hydroxide (KOH) exam and culture in Sabouraud dextrose agar were performed, followed by a biopsy with hematoxylin and eosin, periodic acid‐schiff (PAS) and Gomori‐Grocott stains. The same investigations were carried out in four control cases of noninflammatory tinea capitis.Results  Clinical history varied from 2 to 16 weeks (mean 6.6 weeks). Diagnosis was confirmed by a positive KOH exam: all cases except one had a positive culture. The following dermatophytes were isolated: Microsporum canis (32%), Trichophyton mentagrophytes (27%), Trichophyton tonsurans (21%), Trichophyton rubrum (10%) and Microsporum gypseum (5%). The histopathological findings were: suppurative folliculitis (SF) 11%, SF plus suppurative dermatitis 37%, suppurative and granulomatous dermatitis (SGD) 26% and SGD plus fibrosing dermatitis 26%. Fungi were observed in 63% of the histopathological sections. Perifollicular infiltrates (PF) around the parasitized hair follicles were identified in the four noninflammatory control cases due to M. canis.Conclusions  Kerion Celsi is an inflammatory or suppurative type of tinea capitis caused by zoophylic dermatophytes (M. canis and T. mentagrophytes), but also by antrophophylic (T. tonsurans and T. rubrum) and geophylic (M. gypseum) dermatophytes. Histopathological findings showed a spectrum from mild suppurative folliculitis to dense granulomatous infiltrates without a clear relationship with the clinical features.
Prodromal bullous pemphigoid
Authors: Lamb Philina M. , Abell Edward , Tharp Michael , Frye Roy , Deng Jau‐Shyong 
Published: February 2006

AbstractBackground  Prodromal bullous pemphigoid (PBP) can be difficult to diagnose. Early recognition in its early stages may decrease the morbidity and progression of the disease. Clinical presentations and current treatments available for PBP will be described.Methods  A retrospective review was performed on 53 patients diagnosed with PBP.Results  Overall, the average disease duration of PBP was 11.8 months. The average age of presentation of PBP was 70.8 years. The most common presentations were urticaria‐like plaques (67.9%), eczema‐like lesions (11.3%), and dermatitis herpetiformis‐like lesions (9.4%). The majority of patients responded well to low doses of systemic corticosteroids, tetracycline, and/or high potency topical corticosteroids.Conclusions  Patients with PBP tend to be in their sixth or early seventh decade of life and, on average, the duration of disease is 1 year. The most common presentation of disease is urticaria‐like plaques.