bluuebunny/crossref_metadata_2025 huggingface dataset:
Reinforcing of Porous Hydroxyapatite Ceramics with Hydroxyapatite Fibres for Enhanced Bone Tissue Engineering
Authors: Liang Lie Feng , Han Xiao Yi , Yan Xiao Cai , Weng Jie
Published: May 2011

Porous hydroxyapatite (HA) ceramic implants have attracted attention in bone tissue engineering due to their excellent bioactivity and biocompatibility due to their chemical similarity with the mineral component of natural bone. Unfortunately, HA when is formed into porous structures exhibits very low compression strength. In this study, fabrication of porous HA ceramic scaffolds containing HA fibers is presented. The primary aim of the study is to improve mechanical properties of the scaffold by introducing the fiber with uniform component relative to the scaffold. Scanning electron microscopy was used to observe the surface morphology and pore size of the scaffold. X-ray diffraction (XRD) was used to detect the phase composition and crystallinity of the scaffold. The compressive strength was determined using a universal material test machine. The results and the characterizations demonstrate the addition of HA fiber could enhance the uniformity of mechanical properties among samples and also the strength for a given open porosity.
Downscaled Capillary Pressure and Relative Permeability of Small Cores for Network Model Validation
Authors: Olafuyi O.A. , Cinar Y. , Knackstedt M.A. , Pinczewski W.V.
Published: May 2011

This paper presents the results of drainage capillary pressure and relative permeability measurements made on cores having different bulk volumes ranging from 0.5 to 12 cm3. The aim of the experiments was to provide reliable experimental data which can be used to validate the predictive value of micro-CT based network models for capillary pressure and relative permeability. The micro-CT based network models use realistic networks constructed from the X-ray images of the rock samples having a typical bulk volume of 0.3 cm3. Experimental data for drainage capillary pressure were obtained using the centrifuge technique. The results of the largest cores were verified by the data obtained on the same sample using the porous plate technique. Relative permeability data were obtained by history matching the unsteady state displacement data. Homogeneous model sandstones (Berea and Bentheim) and carbonate (Mt. Gambier) were used in the experiments. Air-brine and oil-brine fluid-systems were used for drainage capillary pressure and relative permeability measurements, respectively. The relative permeability data were compared with those predicted from empirical and geometry based models using capillary pressure data. Good agreement was obtained for the drainage capillary pressure measured on all samples used. The residual saturations obtained from the cores used in the displacement experiments were also in good agreement. The models were found to predict relative permeability of oil and water with varying degrees of success. For water relative permeability, the Pirson model predicts the experimental data successfully while the Corey, Corey-Brooks/Burdine and van Genuchten/Burdine models predict the data of oil relative permeability better than the others. The results demonstrate for the first time that reliable drainage capillary pressure and relative permeability measurements can be made on small model sandstone and carbonate cores of representative scales used in micro-CT-imaging.
Tensile Deformation Behaviors of Ultra-Fine Subgrained Aluminum
Authors: Xu Xiao Jing , Cheng Cheng , Luo Yong , Song Tao , Fei Zhen Dan
Published: May 2011

Tensile deformation behaviors up to peak stress of the ultra-fine subgrained aluminum (2024Al) with the subgrain sizes of about 250 nm and low dislocation density inside were investigated. The results show that the ultra-fine subgrained aluminum exhibited high strain hardening and large uniform plastic strain (19.3 %), but little post-deformation hardness/dislocation density increases (99.6 HV vs. 100.3 HV and 0.79×1014 m-2 vs. 1.03×1014 m-2, respectively). The theoretical calculation based on Taylor equation demonstrated that the dislocation density increase during the tensile deformation up to peak stress was very enormous (1.64×1015 m-2). These results not only implied that the dislocations involved in the tensile deformation were in large quantities but most of them disappeared upon the unloading of the tensile deformation, but also demonstrated that high strain hardening capacity is not a sufficient factor for ultra-fine subgrained metals to store deformation dislocations leading to post-deformation hardness increases.
Recent Progress in the Understanding of Si-Nanostructures Formation in a-SiNx:H Thin Film for Si-Based Optoelectronic Devices
Authors: Singh Sarab Preet , Srivastava Pankaj
Published: May 2011

There has been a rapidly increasing interest in the synthesis and characterization of Si- nanostructures embedded in a dielectric matrix, as it can lead to energy-efficient and cost-effective Complementary Metal-Oxide-Semiconductor (CMOS)-compatible Si-based light sources for optoelectronic integration. In the present contribution, first an overview of the SiOx as a dielectric matrix and its limitations are discussed. We then review the literature on hydrogenated amorphous silicon nitride (a-SiNx:H) as a dielectric matrix for Si-nanostructures, which have been carried out using silane (SiH4) and ammonia (NH3) as the reactant gases. Our studies demonstrate that the least amount of hydrogen in the as-deposited (ASD) a-SiNx:H films not only allows in-situ formation of Si-nanostructures but also stabilizes silicon nitride (Si3N4) phase. The recent advances made in controlling the shape and size of Si-nanostructures embedded in a-SiNx:H matrix by swift heavy ion (SHI) irradiation are briefly discussed.
Systemic Inflammation Modulates Fc Receptor Expression on Microglia during Chronic Neurodegeneration
Authors: Lunnon Katie , Teeling Jessica L. , Tutt Alison L. , Cragg Mark S. , Glennie Martin J. , Perry V. Hugh
Published: May 2011

Chronic neurodegeneration is a major worldwide health problem, and it has been suggested that systemic inflammation can accelerate the onset and progression of clinical symptoms. A possible explanation is that systemic inflammation “switches” the phenotype of microglia from a relatively benign to a highly aggressive and tissue-damaging phenotype. The current study investigated the molecular mechanism underlying this microglia phenotype “switching.” We show in mice with chronic neurodegeneration (ME7 prion model) that there is increased expression of receptors that have a key role in macrophage activation and associated signaling pathways, including TREM-2, Siglec-F, CD200R, and FcγRs. Systemic inflammation induced by LPS further increased protein levels of the activating FcγRIII and FcγRIV, but not of other microglial receptors, including the inhibitory FcγRII. In addition to these changes in receptor expression, IgG levels in the brain parenchyma were increased during chronic neurodegeneration, and these IgG levels further increased after systemic inflammation. γ-Chain–deficient mice show modified proinflammatory cytokine expression in the brain after systemic inflammation. We conclude that systemic inflammation during chronic neurodegeneration increases the expression levels of activating FcγR on microglia and thereby lowers the signaling threshold for Ab-mediated cell activation. At the same time, IgG influx into the brain could provide a cross-linking ligand resulting in excessive microglia activation that is detrimental to neurons already under threat by misfolded protein.
Involvement of Twisted Gastrulation in T Cell-Independent Plasma Cell Production
Authors: Tsalavos Sotiris , Segklia Katerina , Passa Ourania , Petryk Anna , O’Connor Michael B. , Graf Daniel
Published: May 2011

Bone morphogenetic protein (BMP) signaling is increasingly implicated in immune cell differentiation and function; however, direct in vivo evidence for such a role is still missing. In this article, we report that Twisted gastrulation (TWSG1), an extracellular regulator of BMP signaling, is expressed in activated B cells and regulates T-independent B cell responses in the mouse. Twsg1-deficient B cells mount stronger T-independent type 2 responses reflected as increased IgM levels and numbers of Ag-specific IgM-secreting cells. BCR stimulation of Twsg1-deficient B cells results in hyperproliferation, hyperresponsiveness, and decreased apoptosis, whereas TLR stimulation results in hyperproliferation and increased IgG3 production. These changes are reflected on the molecular level by increased transcription of Bcl-6, Pax5, and the BMP-responsive gene Id-2. The TWSG1 effects on B cells appear to be cell intrinsic, suggesting that Twsg1 expression in B cells serves to interpret BMP signals on a per-cell basis. In summary, our observations on the role of TWSG1 in B cell function is opening new paths toward the exploration of the role of BMP signaling in immunological processes.
LIGHT Regulates Inflamed Draining Lymph Node Hypertrophy
Authors: Zhu Mingzhao , Yang Yajun , Wang Yugang , Wang Zhongnan , Fu Yang-Xin
Published: May 2011

Lymph node (LN) hypertrophy, the increased cellularity of LNs, is the major indication of the initiation and expansion of the immune response against infection, vaccination, cancer, or autoimmunity. The mechanisms underlying LN hypertrophy remain poorly defined. In this article, we demonstrate that LIGHT (homologous to lymphotoxins, exhibits inducible expression, and competes with HSV glycoprotein D for HVEM, a receptor expressed by lymphocytes) (TNFSF14) is a novel factor essential for LN hypertrophy after CFA immunization. Mechanistically, LIGHT is required for the influx of lymphocytes into but not egress out of LNs. In addition, LIGHT is required for dendritic cell migration from the skin to draining LNs. Compared with wild type mice, LIGHT−/− mice express lower levels of chemokines in skin and addressins in LN vascular endothelial cells after CFA immunization. We unexpectedly observed that LIGHT from radioresistant rather than radiosensitive cells, likely Langerhans cells, is required for LN hypertrophy. Importantly, Ag-specific T cell responses were impaired in draining LNs of LIGHT−/− mice, suggesting the importance of LIGHT regulation of LN hypertrophy in the generation of an adaptive immune response. Collectively, our data reveal a novel cellular and molecular mechanism for the regulation of LN hypertrophy and its potential impact on the generation of an optimal adaptive immune response.
B Lymphocyte Commitment Program Is Driven by the Proto-Oncogene c-myc
Authors: Vallespinós Mireia , Fernández David , Rodríguez Lorena , Alvaro-Blanco Josué , Baena Esther , Ortiz Maitane , Dukovska Daniela , Martínez Dolores , Rojas Ana , Campanero Miguel R. , Moreno de Alborán Ignacio
Published: May 2011

c-Myc, a member of the Myc family of transcription factors, is involved in numerous biological functions including the regulation of cell proliferation, differentiation, and apoptosis in various cell types. Of all of its functions, the role of c-Myc in cell differentiation is one of the least understood. We addressed the role of c-Myc in B lymphocyte differentiation. We found that c-Myc is essential from early stages of B lymphocyte differentiation in vivo and regulates this process by providing B cell identity via direct transcriptional regulation of the ebf-1 gene. Our data show that c-Myc influences early B lymphocyte differentiation by promoting activation of B cell identity genes, thus linking this transcription factor to the EBF-1/Pax-5 pathway.
Regulatory T Cells Target Chemokine Secretion by Dendritic Cells Independently of Their Capacity To Regulate T Cell Proliferation
Authors: Morlacchi Sara , Dal Secco Valentina , Soldani Cristiana , Glaichenhaus Nicolas , Viola Antonella , Sarukhan Adelaida
Published: May 2011

The clinical manipulation of regulatory T cells (Tregs) represents a promising strategy for the regulation of unwanted immune responses. It is now becoming clear that Tregs exert multiple effects on different cell targets under particular conditions; however, the interplay between these different factors remains unclear. Using mouse Tregs of known Ag specificity, we report in this study two different levels of Treg-mediated suppression: one that targets T cell proliferation and one that targets dendritic cell-mediated proinflammatory chemokine (CCL3 and CCL4) production. These two effects can be dissociated, and whereas modulation of T cell proliferation depends on the strength of the antigenic stimulus, modulation of chemokine production by dendritic cells does not. We also provide evidence that the bystander effect of Tregs on immune responses observed in vivo may be in great part explained by a decrease in the recruitment of target T cells, and therefore in the magnitude of the response, rather than by a direct effect on their priming or proliferation. Overall, our results shed some light on the different aspects that need to be considered when attempting to modulate Tregs for clinical purposes.
IFN-γ Secreted by CD103+ Dendritic Cells Leads to IgG Generation in the Mesenteric Lymph Node in the Absence of Vitamin A
Authors: Chang Jae-Hoon , Cha Hye-Ran , Chang Sun-Young , Ko Hyun-Jeong , Seo Sang-Uk , Kweon Mi-Na
Published: May 2011

Although the induction mechanism of secretory IgA has been well studied, that of IgG in the mucosal compartments is not well understood. In this study, vitamin A deficiency was convincingly shown to be associated with increased IgG in serum and intestinal fluid. We found increased numbers of IgG-secreting B cells in the lamina propria of the small intestine and mesenteric lymph node (MLN) of vitamin A-deficient (VAD) mice. Of note, IFN-γ secreted by MLN dendritic cells (DCs) was significantly augmented in VAD mice, unlike control mice, and CD103+ DCs were the main subsets to secrete IFN-γ. The aberrant increase of IgG in VAD mice can be ascribable to IFN-γ, because IFN-γ−/− VAD mice have normal IgG levels and the addition of rIFN-γ increased IgG production by B cells cocultured with MLN DCs from IFN-γ−/− VAD mice. Oral feeding of antibiotics resulted in significant reduction of IgG in VAD mice, indicating a critical role for altered commensal bacteria for IgG class-switching recombination in the absence of vitamin A. Collectively, vitamin A deficiency provokes the generation of IFN-γ–secreting CD103+ DCs, which may be a critical regulator for IgG generation in the MLN.
Airway Epithelial MyD88 Restores Control of Pseudomonas aeruginosa Murine Infection via an IL-1–Dependent Pathway
Authors: Mijares Lilia A. , Wangdi Tamding , Sokol Caroline , Homer Robert , Medzhitov Ruslan , Kazmierczak Barbara I.
Published: May 2011

The opportunistic human pathogen Pseudomonas aeruginosa causes rapidly progressive and tissue-destructive infections, such as hospital-acquired and ventilator-associated pneumonias. Innate immune responses are critical in controlling P. aeruginosa in the mammalian lung, as demonstrated by the increased susceptibility of MyD88−/− mice to this pathogen. Experiments conducted using bone marrow chimeric mice demonstrated that radio-resistant cells participated in initiating MyD88-dependent innate immune responses to P. aeruginosa. In this study we used a novel transgenic mouse model to demonstrate that MyD88 expression by epithelial cells is sufficient to generate a rapid and protective innate immune response following intranasal infection with P. aeruginosa. MyD88 functions as an adaptor for many TLRs. However, mice in which multiple TLR pathways (e.g., TLR2/TLR4/TLR5) are blocked are not as compromised in their response to P. aeruginosa as mice lacking MyD88. We demonstrate that IL-1R signaling is an essential element of MyD88-dependent epithelial cell responses to P. aeruginosa infection.
Natural but Not Inducible Regulatory T Cells Require TNF-α Signaling for In Vivo Function
Authors: Housley William J. , Adams Catherine O. , Nichols Frank C. , Puddington Lynn , Lingenheld Elizabeth G. , Zhu Li , Rajan Thiruchandurai V. , Clark Robert B.
Published: May 2011

TNF-α has a multifunctional role in autoimmune diseases as reflected in the variable responses of different human diseases to anti–TNF-α therapy. Recent studies have suggested that TNF-α modulates autoimmunity partially via effects on regulatory T cells (Tregs) and that these effects are mediated through the type II TNFR (TNFR2). We have investigated the requirement for TNFR2-expression on murine natural Tregs (nTregs) and induced Tregs (iTregs) in mediating suppression of colitis. Surprisingly, we find that TNFR2-expression is required for both spleen- and thymus-derived nTreg-mediated suppression, but is not required for iTreg-mediated suppression. Abnormal TNFR2−/− nTreg function was not associated with an in vivo decrease in accumulation, stability, or expression of markers known to be relevant in Treg function. Because iTregs are generated in the presence of TGF-β, we investigated whether activation in the presence of TGF-β could overcome the functional defect in TNFR2−/− nTregs. Although preactivation alone did not restore suppressive function of nTregs, preactivation in the presence of TGF-β did. These results identify potentially critical differences in activation requirements for nTregs versus iTregs. Furthermore, our findings are consistent with reports suggesting that nTregs are activated in sites of inflammation while iTregs are activated in lymph nodes. Finally, by demonstrating that nTregs require TNF-α for optimal function whereas iTregs do not, our results suggest that the enigma of variable responses of different human diseases to anti–TNF-α therapy may relate to whether nTregs or iTregs have the predominant regulatory role in a given disease.
Invariant NKT Cells Producing IL-4 or IL-10, But Not IFN-γ, Inhibit the Th1 Response in Experimental Autoimmune Encephalomyelitis, Whereas None of These Cells Inhibits the Th17 Response
Authors: Oh Sae Jin , Chung Doo Hyun
Published: May 2011

Experimental autoimmune encephalomyelitis (EAE) is mediated by Th1 and Th17 cells. Invariant NKT (iNKT) cells prevent EAE in an IL-4–, IL-10–, and IFN-γ–dependent manner. However, which of the iNKT cell-produced cytokines regulates the Th1 or Th17 response in EAE remains unclear. Wild-type B6 and Jα18−/− mice were immunized with MOG35–55 peptide to address this issue. Clinical scores for EAE, IL-17, and IFN-γ transcript levels, and IL-17– or IFN-γ–expressing CD4+ T cell percentages in the CNS and draining lymph nodes were higher in Jα18−/− than in B6 mice, but all of these parameters in the CNS were reduced by the adoptive transfer of wild-type or IFN-γ–deficient iNKT cells into the Jα18−/− mice before immunization. In contrast, adoptive transfer of IL-4– or IL-10–deficient iNKT cells into Jα18−/− mice decreased IL-17 transcript levels and the percentage of IL-17–expressing CD4+ T cells in the CNS but did not affect clinical scores, IFN-γ transcript levels, or the percentage of IFN-γ–expressing CD4+ T cells in the CNS. Taken together, IL-4– and IL-10–producing iNKT cells inhibit the Th1 cell response, but not the Th17 cell response, although wild-type iNKT cells suppress both the Th1 and Th17 responses in the CNS during EAE. Moreover, IFN-γ–producing iNKT cells have a minimal role in the regulation of the Th1 and Th17 responses in EAE.
Cutting Edge: IL-15–Independent Maintenance of Mucosally Generated Memory CD8 T Cells
Authors: Verbist Katherine C. , Field Mary B. , Klonowski Kimberly D.
Published: May 2011

Effective vaccines against intracellular pathogens rely on the generation and maintenance of memory CD8 T cells (Tmem). Hitherto, evidence has indicated that CD8 Tmem use the common γ-chain cytokine IL-15 for their steady-state maintenance in the absence of Ag. This evidence, however, has been amassed predominantly from models of acute, systemic infections. Given that the route of infection can have significant impact on the quantity and quality of the resultant Tmem, reliance on limited models of infection may restrict our understanding of long-term CD8 Tmem survival. In this article, we show IL-15–independent generation, maintenance, and function of CD8 Tmem after respiratory infection with influenza virus. Importantly, we demonstrate that alternating between mucosal and systemic deliveries of the identical virus prompts this change in IL-15 dependence, necessitating a re-evaluation of the current model of CD8 Tmem maintenance.
Genetic Segregation of Inflammatory Lung Disease and Autoimmune Disease Severity in SHIP-1−/− Mice
Authors: Maxwell Mhairi J. , Duan Mubing , Armes Jane E. , Anderson Gary P. , Tarlinton David M. , Hibbs Margaret L.
Published: May 2011

Alternatively activated M2 macrophages are implicated as both regulators and agents of lung disease, but their control is poorly understood. SHIP-1 is a 5′ inositol phosphatase that negatively regulates the PI3K signaling pathway implicated in inflammation. SHIP-1–deficient mice have defects in hematopoiesis and B cell development, and die prematurely due to consolidation of lungs with M2-skewed macrophages. SHIP-1 is thought to restrain M2 macrophage polarization, with deregulated M2 skewing coinciding with severe lung disease in SHIP-1–deficient mice. To determine the influence of genetic background on the lung phenotype in SHIP-1−/− mice, we backcrossed the SHIP-1 null mutation onto C57BL/6 (Th2-resistant) and BALB/c (Th2-prone) backgrounds. Remarkably, we found that inflammatory lung disease was severe in C57.SHIP-1−/− mice, but absent in BALB.SHIP-1−/− mice. C57.SHIP-1−/−, but not BALB.SHIP-1−/− mice had greatly increased myeloid progenitors, myeloid hyperplasia, markedly enhanced numbers of activated alveolar macrophages, and elevated amounts of Th2 and proinflammatory cytokines in bronchoalveolar lavage fluid and serum, suggesting that deregulated cytokine production induced disease. C57.SHIP-1−/− mice also developed severe B cell-dependent autoimmune disease, which was markedly attenuated on the BALB/c background. These data demonstrate that, contrary to current concepts, loss of SHIP-1 alone is not sufficient to cause lung inflammation, with disease only manifest on a permissive genetic background. This finding questions the nature of the lung disease in SHIP-1−/− mice, suggesting that its M2 classification is not strictly correct. Future identification of disease-promoting loci might reveal determinants of comorbid lung disease and autoimmunity and uncover potentially useful therapeutic targets.
Activation of Endothelial Roundabout Receptor 4 Reduces the Severity of Virus-Induced Keratitis
Authors: Mulik Sachin , Sharma Shalini , Suryawanshi Amol , Veiga-Parga Tamara , Reddy Pradeep B. J. , Rajasagi Naveen K. , Rouse Barry T.
Published: May 2011

Antiangiogenic molecules exert a feedback control to restrain pathological angiogenesis, which includes physical binding or inhibition of angiogenic signaling in blood vessel endothelial cells. The latter is the case in which Slit2 ligand-dependent activation of the blood vessel endothelial cell receptor roundabout 4 (Robo4) occurs. In this study, we demonstrate that Robo4 receptors are upregulated following HSV infection of the eye on the majority of the new blood vessel endothelial cells that occur in the corneal stroma. However, expression levels of the ligand for Robo4 receptors, Slit2, was not significantly increased during the disease process, and the knockdown of Slit2 gene expression using lentiviral short hairpin RNAs had no effect on the extent of pathological angiogenesis. In contrast, providing additional Slit2 protein by subconjunctival administration resulted in significantly reduced angiogenesis. The Slit2 binding to Robo4 was shown to block the downstream vascular endothelial growth factor signaling molecules Arf 6 and Rac 1 and reduce the antiapoptotic molecule Bcl-xL in blood vessel endothelial cells. Our results indicate that augmenting the host Robo4/Slit2 system could provide a useful therapeutic approach to control pathological angiogenesis associated with HSV induced stromal keratitis.
Proteasomes, TAP, and Endoplasmic Reticulum-Associated Aminopeptidase Associated with Antigen Processing Control CD4+ Th Cell Responses by Regulating Indirect Presentation of MHC Class II-Restricted Cytoplasmic Antigens
Authors: Dragovic Srdjan M. , Hill Timothy , Christianson Gregory J. , Kim Sungjune , Elliott Tim , Scott Diane , Roopenian Derry C. , Van Kaer Luc , Joyce Sebastian
Published: May 2011

Cytoplasmic Ags derived from viruses, cytosolic bacteria, tumors, and allografts are presented to T cells by MHC class I or class II molecules. In the case of class II-restricted Ags, professional APCs acquire them during uptake of dead class II-negative cells and present them via a process called indirect presentation. It is generally assumed that the cytosolic Ag-processing machinery, which supplies peptides for presentation by class I molecules, plays very little role in indirect presentation of class II-restricted cytoplasmic Ags. Remarkably, upon testing this assumption, we found that proteasomes, TAP, and endoplasmic reticulum-associated aminopeptidase associated with Ag processing, but not tapasin, partially destroyed or removed cytoplasmic class II-restricted Ags, such that their inhibition or deficiency led to dramatically increased Th cell responses to allograft (HY) and microbial (Listeria monocytogenes) Ags, both of which are indirectly presented. This effect was neither due to enhanced endoplasmic reticulum-associated degradation nor competition for Ag between class I and class II molecules. From these findings, a novel model emerged in which the cytosolic Ag-processing machinery regulates the quantity of cytoplasmic peptides available for presentation by class II molecules and, hence, modulates Th cell responses.
Cutting Edge: The Membrane Attack Complex of Complement Is Required for the Development of Murine Experimental Cerebral Malaria
Authors: Ramos Theresa N. , Darley Meghan M. , Hu Xianzhen , Billker Oliver , Rayner Julian C. , Ahras Malika , Wohler Jillian E. , Barnum Scott R.
Published: May 2011

Cerebral malaria is the most severe complication of Plasmodium falciparum infection and accounts for a large number of malaria fatalities worldwide. Recent studies demonstrated that C5−/− mice are resistant to experimental cerebral malaria (ECM) and suggested that protection was due to loss of C5a-induced inflammation. Surprisingly, we observed that C5aR−/− mice were fully susceptible to disease, indicating that C5a is not required for ECM. C3aR−/− and C3aR−/− × C5aR−/− mice were equally susceptible to ECM as were wild-type mice, indicating that neither complement anaphylatoxin receptor is critical for ECM development. In contrast, C9 deposition in the brains of mice with ECM suggested an important role for the terminal complement pathway. Treatment with anti-C9 Ab significantly increased survival time and reduced mortality in ECM. Our data indicate that protection from ECM in C5−/− mice is mediated through inhibition of membrane attack complex formation and not through C5a-induced inflammation.
Genetic Variation Determines Mast Cell Functions in Experimental Asthma
Authors: Becker Marc , Reuter Sebastian , Friedrich Pamela , Doener Fatma , Michel Anastasija , Bopp Tobias , Klein Matthias , Schmitt Edgar , Schild Hansjörg , Radsak Markus P. , Echtenacher Bernd , Taube Christian , Stassen Michael
Published: May 2011

Mast cell-deficient mice are a key for investigating the function of mast cells in health and disease. Allergic airway disease induced as a Th2-type immune response in mice is employed as a model to unravel the mechanisms underlying inception and progression of human allergic asthma. Previous work done in mast cell-deficient mouse strains that otherwise typically mount Th1-dominated immune responses revealed contradictory results as to whether mast cells contribute to the development of airway hyperresponsiveness and airway inflammation. However, a major contribution of mast cells was shown using adjuvant-free protocols to achieve sensitization. The identification of a traceable genetic polymorphism closely linked to the KitW-sh allele allowed us to generate congenic mast cell-deficient mice on a Th2-prone BALB/c background, termed C.B6-KitW-sh. In accordance with the expectations, C.B6-KitW-sh mice do not develop IgE- and mast cell-dependent passive cutaneous anaphylaxis. Yet, unexpectedly, C.B6-KitW-sh mice develop full-blown airway inflammation, airway hyperresponsiveness, and mucus production despite the absence of mast cells. Thus, our findings demonstrate a major influence of genetic background on the contribution of mast cells in an important disease model and introduce a novel strain of mast cell-deficient mice.
Laparoscopic-Assisted Cryptorchidectomy in an Adult Reindeer (Rangifer tarandus)
Authors: Pizzi Romain , Girling Simon , Bell Andrew , Tjolle Adam , Brown Donna , Devine Craig
Published: May 2011

A successful laparoscopic-assisted cryptorchidectomy is reported in a novel species, the reindeer (Rangifer tarandus). The procedure was performed in an 8-year-old adult positioned in dorsolateral oblique recumbency, with an open approach midline subumbilical placement of the primary 10 mm optical port and carbon dioxide insufflation at 12 mmHg. Three 5 mm instrument ports were inserted under visualization in the left caudal abdomen as the retained testicle was localized to the internal inguinal ring. A 5 mm flexible organ retractor was used to assist in localizing the retained testicle. This procedure provided a less invasive alternative to open laparotomy. The authors are unaware of any published reports of laparoscopy in reindeer, or of laparoscopic assisted cryptorchidectomy in deer species.
Liver Surgery for Hepatocellular Carcinoma: Laparoscopic versus Open Approach
Authors: Ker C. G. , Chen J. S. , Kuo K. K. , Chuang S. C. , Wang S. J. , Chang W. C. , Lee K. T. , Chen H. Y. , Juan C. C.
Published: May 2011

In this study, we try to compare the benefit of laparoscopic versus open operative procedures.Patients and Methods. One hundred and sixteen patients underwent laparoscopic liver resection (LR) and another 208 patients went for open liver resection (OR) for hepatocellular carcinoma (HCC). Patients' selection for open or laparoscopic approach was not randomized.Results. The CLIP score for LR and OR was 0.59 ± 0.75 and 0.86 ± 1.04, respectively, (). The operation time was 156.3 ± 308.2 and 190.9 ± 79.2 min for LR and OR groups, respectively. The necessity for blood transfusion was found in 8 patients (6.9%) and 106 patients (50.9%) for LR and OR groups. Patients resumed full diet on the 2nd and 3rd postoperative day, and the average length of hospital stay was 6 days and 12 days for LR and OR groups. The complication rate and mortality rate were 0% and 6.0%, 2.9% and 30.2% for LR and OR groups, respectively. The 1-yr, 3-yr, and 5-yr survival rate was 87.0%, 70.4%, 62.2% and 83.2%, 76.0%, 71.8% for LR and OR group, respectively, of non-significant difference. From these results, HCC patients accepted laparoscopic or open approach were of no significant differences between their survival rates.
Respiratory symptoms amongst females in a fishing settlement in the Niger Delta, Nigeria
Authors: Akani Alexander B. , Dienye Paul O. , Okokon Ita B.
Published: May 2011

Background: Approximately half of the earth’s population in the rural areas of developing countries uses energy obtained from biomass burning, which is harmful to people.Objective: This study is aimed at determining which respiratory symptoms can be associated with biomass burning amongst fish smokers in the Oyorokoto fishing settlement. Methods: A community-based, cross-sectional questionnaire, which employed a modified cluster sampling technique, was used.Results: A total of 300 subjects were recruited for the study, of which 210 (70%) were fish smokers. The mean age was 31.46 ± 13.03 years, with the majority (42.0%) having only primary school education. The prevalence of respiratory symptoms amongst the subjects was 86.7%,the most frequent of which were catarrh (30.48%) and a cough (28.57%). The respiratory symptom occurring least frequently was breathlessness (2.38%). The symptoms most often experienced during fish smoking were those of catarrh (75.5%) and sneezing (73.0%), whereas breathlessness occurred the least, in only 7 (3.3%) of the participants. Sneezing stopped in 64.2% of the subjects after fish smoking had ceased. Most of the fish smoking took place indoors.Conclusion: Health promotion featuring preventive interventions, such as the wearing of facemasks and the use of modern fish smoking methods, which is associated with fewer health risks, is essential to improving the quality of life of fish smokers. The government’s provision of certain social services, including better education opportunities for the young, is advocated, and should be especially targeted at improving the lot of the girl child.
Evaluation of Perceived Quality of the Website of an Online Bookstore: an Empirical Application of the Barnes and Vidgen Model
Authors: Leonidio Ueliton da Costa , Montezano Roberto Marcos da Silva , Carvalho Frederico A. de
Published: May 2011

This paper’s objective is to evaluate the perceived quality of the Website of an online bookstore using the Barnes and Vidgen Model. Implemented over the Internet, this empirical research collected data on the perceived quality of the Website, used to sell products and online services. The questionnaire used to gather the data was answered by a convenience sample of 213 respondents. The importance of quality attributes and the dimension of perceived quality were investigated. The results indicate that the three dimensions named Reliability, Usability and Information were the most noticeable.
Teach-Me: Implementation of Mobile Environments to the Teach - Learning Process
Authors: Peregrino Luis Eduardo Pérez , Matallana Adriana Maritza , Pérez Frey Rodríguez , Pinilla Alejandro Moreno , Cubides Jhon Herrera
Published: May 2011

The research project TEACH-ME (Technology, Engineering Calculus and Hewlett-Packard Mobile Environment) presents an educational proposal that seeks to innovate the teaching and learning processes of mathematics, Logic Basic Programming and Management of Information, through the introduction of collaborative working environments, in order to provide the integrated development of learning methodologies, enhancing cognitive abilities in their students. As a case study, it presents the results obtained when applying this project to students in their first semester at the Faculty of Engineering at “Corporación Universitaria Minuto de Dios” University, which introduces the use of tablet PCs from Hewlett Packard to support the teaching process. This article presents the process of implementing of the TEACH-ME Project, developed as an academic environment that has allowed the implementation processes of research on the impact of the application of information technologies and communication technologies to the higher education teaching. We will present the project background, what the implementation process has so far done, the impact obtained from the learning and teaching processes, the integration of technologies at an academic meeting who has helped carry out the project and, finally, the contributions of the Tablet PC to the teaching-learning process at the University.
Gestão do Conhecimento em Transnacionais: O Ambiente Organizacional como Instrumento Disseminador
Authors: Cunha Julio Araujo Carneiro da , Yokomizo Cesar Akira , Capellini Gustavo de Almeida
Published: May 2011

National economies are gradually opening wide for international trade; this trend compels organizations, mainly the internationalized ones, to be more prepared to effectively and efficiently compete worldwide. In this context, the goal of this study was to identify and describe strategies and practices which promote knowledge flows within an international organization that holds its headquarter in a developed country and subsidiaries in developing countries. Methodological procedures include the explicit examination of codified information between subsidiaries units, through interviews and document analysis, in order to capture the tacit dimension in the causal maps that were made. Main results show an organizational strategy focused on the continuous stimuli to the construction of an organizational environment, embedded with solicitude between knowledge senders and receivers, and with a formal information management that supports knowledge exchanges and flows in a worldwide context.
Uncoupling of chitinase activity and uptake of hydrolysis products in freshwater bacterioplankton
Authors: Beier Sara , Bertilsson Stefan
Published: May 2011

We investigated to what extent chitinolytic bacteria subsidize bacterial populations that do not produce chitinolytic enzymes but still use the products of chitin hydrolysis. Applying single‐cell techniques to untreated and chitin‐enriched lake water, we show that the number of planktonic cells taking up chitin hydrolysis products by far exceeds the number of cells expressing chitinases. Flavobacteria, Actinobacteria, and specifically members of the abundant and ubiquitous freshwater Ac1 cluster of the Actinobacteria, increased in abundance and were enriched in response to the chitin amendment. Flavobacteria were frequently observed in dense clusters on chitin particles, suggesting that they are actively involved in the hydrolysis and solubilization of chitin. In contrast, Actinobacteria were exclusively planktonic. We propose that planktonic Actinobacteria contain commensals specialized in the uptake of small hydrolysis products without expressing or possibly even possessing the machinery for chitin hydrolysis. More research is needed to assess the importance of such “cheater” substrate acquisition strategies in the turnover and degradation of polymeric organic matter in aquatic ecosystems.
Microbial dinitrogen and nitrous oxide production in a small eutrophic reservoir: An in situ approach to quantifying hypolimnetic process rates
Authors: Deemer Bridget R. , Harrison John A. , Whitling Elliott W.
Published: May 2011

Nitrogen (N) dynamics within the hypolimnion of a thermally stratified reservoir were examined to test an in situ approach to measuring dinitrogen (N2) and nitrous oxide (N2O) production rates wherein hypolimnion gas accumulation is used to estimate N2 and N2O production. This previously unpublished approach provides a spatially integrated, time‐varying record of N transformation rates that fall well within the range of rates reported for other reservoir systems using other methods. Hypolimnion N2 production averaged 183 μmol N2‐N m−2 h−1 with higher rates observed early in a spring stratification event (538 μmol N2‐N m−2 h−1) and lower rates observed later in the same stratification event (90 μmol N2‐N m−2 h−1). Sediment incubation experiments and hypolimnion nitrate (NO−3) data show that, over the course of the summer, progressive NO−3 depletion at the sediment‐water interface limited N2 production and associated N removal. As rates of N2 production dropped off, rates of N2O production increased (from 4.62 μmol N2O‐N m−2 d−1 to 51 μmol N2O‐N m−2 d−1, averaging 26 μmol N2O‐N m−2 d−1), resulting in significant increases in N2O‐N : N2‐N ratios as the summer progressed. Also, whereas N2 production appeared to occur predominantly at the sediment‐water interface, N2O production was detected throughout the water column, suggesting a role for nitrification as a source of N2O. The use of hypolimnion accumulation to quantify N transformation rates can thus offer new insights into spatial and seasonal N transformation patterns in stratified or otherwise capped aquatic systems.
Modeling sea-salt aerosol in a coupled climate and sectional microphysical model: mass, optical depth and number concentration
Authors: Fan T. , Toon O. B.
Published: May 2011

Abstract. Sea-salt aerosol mass, optical depth, and number concentration over the global oceans have significant implications for aerosol direct and indirect climate effects. We model sea-salt aerosol in a coupled climate and sectional microphysical model, CAM/CARMA, with aerosol dynamics including sea-salt emission, gravitational sedimentation, dry deposition, wet scavenging, and hygroscopic growth. We aim to find an integrated sea-salt source function parameterization in the global climate model to simultaneously represent mass, optical depth, and number concentration. Each of these quantities is sensitive to a different part of the aerosol size distribution, which requires a size resolved microphysical model to treat properly. The CMS source function introduced in this research, based upon several earlier source functions, reproduces measurements of mass, optical depth and number concentration as well as the size distribution better than other source function choices we tried. However, as we note, it is also important to properly set the removal rate of the particles. The source function and removal rate are coupled in producing observed abundances. We find that sea salt mass and optical depth peak in the winter, when winds are highest. However, surprisingly, particle numbers and CCN concentrations peak in summer when rainfall is lowest. The quadratic dependence of sea-salt optical depth on wind speed, observed by some, is well represented in the model. We also find good agreement with the wind speed dependency of the number concentration at the measurement location and the regional scale. The work is the basis for further investigation of the effects of sea-salt aerosol on climate and atmospheric chemistry.
On the aerosol weekly cycle spatiotemporal variability over Europe
Authors: Georgoulias A. K. , Kourtidis K. A.
Published: May 2011

Abstract. In this work, we focus on the spatial and temporal variability of the aerosol weekly cycle over Europe as these were recorded from TERRA MODIS and AQUA MODIS satellite instruments. Aerosol optical properties retrieved from MODIS TERRA (February 2000–February 2009) and AQUA (July 2002–December 2008) were used to produce an aerosol weekly cycle index. First, the general aerosol optical depth (AOD550 nm) weekly patterns were defined at a 1° × 1° resolution using the satellite-based index and six regions of interest were selected. To remove episodic dust transport events, two different aerosol flags, employing fine mode ratio (FMR550 nm) and AOD550 nm data, were applied diagnostically, showing that the observed weekly cycles over Europe are due to continental aerosols. A second spatial averaging method was then used for the investigation of the weekly variability and the statistical significance of the weekly cycle over each of the previously selected regions. Three major weekly cycle plumes are observed over Europe. A strong positive (higher values during midweek) weekly cycle plume appears over Central Europe, while a strong negative (higher values during weekend) weekly plume appears over the Iberian Peninsula and the North-eastern Europe. The temporal examination of the weekly cycles shows that in some areas there are seasonal differences in the sign of the weekly cycle. The aerosol weekly variability over different regions in Europe was examined in conjunction with the dominating synoptic wind patterns from the NCEP/NCAR reanalysis, showing that the seasonal weekly cycle plumes over regions situated in the eastern Europe and the Mediterranean Sea could be partly attributed to the westerly transport of continental aerosols.
Aerosol composition and sources in the Central Arctic Ocean during ASCOS
Authors: Chang R. Y.-W. , Leck C. , Graus M. , Müller M. , Paatero J. , Burkhart J. F. , Stohl A. , Orr L. H. , Hayden K. , Li S.-M. , Hansel A. , Tjernström M. , Leaitch W. R. , Abbatt J. P. D.
Published: May 2011

Abstract. Measurements of submicron aerosol chemical composition were made in the Central Arctic Ocean from 5 August to 8 September 2008 as a part of the Arctic Summer Cloud Ocean Study (ASCOS) using an aerosol mass spectrometer (AMS). The median levels of sulphate and organics for the entire study were 0.042 and 0.046 μg m−3, respectively. Positive matrix factorisation was performed on the entire mass spectral time series and this enabled marine biogenic and continental sources of particles to be separated. These factors accounted for 33 % and 36 % of the sampled ambient aerosol mass, respectively, and they were both predominantly composed of sulphate, with 47 % of the sulphate apportioned to marine biogenic sources and 48 % to continental sources, by mass. Within the marine biogenic factor, the ratio of methane sulphonate to sulphate was 0.25 ± 0.02, consistent with values reported in the literature. The organic component of the continental factor was more oxidised than that of the marine biogenic factor, suggesting that it was more processed and had been present longer in the atmosphere than the organics in the marine biogenic factor. The remaining ambient aerosol mass was apportioned to an organic-rich factor that could have arisen from a combination of marine and continental sources.
Forest cover influence on flood assessment in Italian catchments
Authors: Preti F. , Forzieri G. , Chirico G. B.
Published: May 2011

Abstract. The paper aims at evaluating to what extent forest cover could affect the flood peak frequency and magnitude in Italian catchments. The analysis is restricted to evaluating the component of the runoff coefficient which cannot be captured by the catchment lithology alone. A preliminary data mining is performed on data of 75 catchments distributed from South to Central Italy. Cluster and correlation structure analyses are conducted for distinguishing forest cover effects within sample sets of catchments characterized by hydro-morphological similarities. We propose a method for correcting the bias of the runoff coefficient estimated from the catchment lithology only, by accounting for the effect of forest cover. The bias correction becomes significant for small mountainous catchments, characterised by larger forest cover fraction and lower critical rainfall depth. Consistently with what suggested in previous studies, the bias correction decreases as the rainfall depth and return period increase.
The seasonal cycle and interannual variability of surface energy balance and melt in the ablation zone of the west Greenland ice sheet
Authors: van den Broeke M. R. , Smeets C. J. P. P. , van de Wal R. S. W.
Published: May 2011

Abstract. We present the seasonal cycle and interannual variability of the surface energy balance (SEB) in the ablation zone of the west Greenland ice sheet, using seven years (September 2003–August 2010) of hourly observations from three automatic weather stations (AWS). The AWS are situated along the 67° N latitude circle at elevations of 490 m a.s.l. (S5), 1020 m a.s.l. (S6) and 1520 m a.s.l. (S9) at distances of 6, 38 and 88 km from the ice sheet margin. The hourly AWS data are fed into a model that calculates all SEB components and melt rate; the model allows for shortwave radiation penetration in ice and time-varying surface momentum roughness. Snow depth is prescribed from albedo and sonic height ranger observations. Modelled and observed surface temperatures for non-melting conditions agree very well, with RMSE's of 0.97–1.26 K. Modelled and observed ice melt rates at the two lowest sites also show very good agreement, both for total cumulative and 10-day cumulated amounts. Melt frequencies and melt rates at the AWS sites are discussed. Although absorbed shortwave radiation is the most important energy source for melt at all three sites, interannual melt variability at the lowest site is driven mainly by variability in the turbulent flux of sensible heat. This is explained by the quasi-constant summer albedo in the lower ablation zone, limiting the influence of the melt-albedo feedback, and the proximity of the snow free tundra, which heats up considerably in summer.