bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutrophil migration during endotoxemia
Authors: Wagner James G , Roth Robert A
Published: January 2018

Endotoxemia is marked by a global activation of inflammatory responses, which can lead to shock, multiple organ failure, and the suppression of immune and wound healing processes. Neutrophils (PMNs) play a central role in some of these responses by accumulating in tissues and releasing reactive oxygen species and proteases that injure host structures. This review focuses on altered PMN migratory responses that occur during endotoxemia and their consequences in the development of pulmonary infection. The inflammatory mediators that might be responsible for these altered responses are discussed. The oxidant potential of PMNs is increased after exposure to endotoxin both in vitro and during clinical and experimental endotoxemia. However, other functions such as chemotaxis and phagocytosis are often depressed in these same cells. Endotoxin exposure renders PMNs hyperadhesive to endothelium. The sum of these effects produces activated inflammatory cells that are incapable of leaving the vasculature. As such, the endotoxic PMN is more likely to promote tissue injury from within microvascular beds than to clear pathogens from extravascular sites. Moreover, the functional characteristics of endotoxic PMNs are similar to those observed during trauma, burn injury, sepsis, surgery, and other inflammatory conditions. Accordingly, several clinical conditions might have a common effector in the activated, yet migratorially dysfunctional, PMN. Direct effects of endotoxin on PMNs as well as effects of endogenous mediators released during endotoxemia are discussed. Understanding PMN behavior during endotoxemia may provide basic and critical insights that can be applied to a number of inflammatory scenarios. J. Leukoc. Biol. 66: 10–24; 1999.
Induction of DAP12 phosphorylation, calcium mobilization, and cytokine secretion by Ly49H
Authors: Gosselin Pierre , Mason Llewellyn H , Willette-Brown Jami , Ortaldo John R , McVicar Daniel W , Anderson Stephen K
Published: January 2018

The ability of several Ly49 family members to inhibit natural killer (NK) cell functions through recruitment of SHP-1 phosphatase has been reported. In contrast, the mechanisms underlying the activating signal generated by Ly49D are poorly understood. A homodimeric phosphoprotein (pp16) that physically and functionally associates with Ly49D has been described. In this study, a rabbit anti-mouse pp16 antiserum was generated and used to demonstrate that pp16 corresponds to the recently described DAP12 molecule. In addition, we show that a second Ly49 family member that lacks an immunoreceptor tyrosine-based inhibitory motif and contains a charged residue in the transmembrane domain, Ly49H, also associates with DAP12. Furthermore, we show that engagement of the Ly49H/DAP12 complex results in phosphorylation of DAP12, intracellular calcium mobilization, and tumor necrosis factor secretion in transfected cells. These results thus provide evidence that Ly49H is an activating receptor that associates with DAP12, previously described as a pp16 component of the Ly49D receptor complex. J. Leukoc. Biol. 66: 165–171; 1999.
Hepatic dendritic cells: immunobiology and role in liver transplantation
Authors: Thomson A W , Drakes M L , Zahorchak A F , O'Connell P J , Steptoe R J , Qian S , Lu L
Published: January 2018

Traditional investigations of hepatic dendritic cells (DC) have focused on immunohistochemical studies of these cells within normal and pathological liver tissue. The recent availability of reagents for the improved characterization of DC, together with cytokine-based methods for the expansion of liver DC both in vivo and in vitro have begun to provide new insight into the immunobiology of these important antigen-presenting cells. Hepatic DC probably play a key role in the host response to blood-borne pathogens, and in the pathogenesis of infectious and autoimmune liver diseases. They appear to be important in determining the balance between liver transplant tolerance and rejection. Their possible role in oral and portal venous tolerance remains to be defined. In this article, we focus on emerging aspects of hepatic DC immunobiology, with particular reference to liver transplantation. J. Leukoc. Biol. 66: 322–330; 1999.
Regulation of the production of soluble IL-4 receptors in murine cutaneous leishmaniasis. The roles of IL-12 and IL-4
Authors: Fernandez-Botran Rafael , Chilton Paula M , Hondowicz Brian D , Vetvickova Jana , Yan Jun , Jones Walter , Scott Phillip
Published: January 2018

These studies were undertaken with the purpose of elucidating the key signals involved in the regulation of the production of soluble interleukin-4 receptors (sIL-4R) in mice during Th1 and Th2 responses to infection with the parasite Leishmania major. Our results showed that the production of sIL-4R was consistently higher in lymph node cell cultures from animals mounting a predominant Th2 response (BALB/c mice), and that sIL-4R production paralleled that of IL-4 in both mouse strains, even in the presence of a dominant Th1 response (C3H/FeJ mice). Consistently, administration of anti-IL-12 antibodies to infected C3H/FeJ mice induced a switch from a Th1- to a Th2-type response and resulted in enhanced production of sIL-4R. Addition of rIL-12 to splenic cell cultures, however, was found not to have a direct effect on sIL-4R production induced by IL-4 or T cell mitogens. Moreover, the production of sIL-4R appears to be little influenced by Th1-produced cytokines, inasmuch as recombinant interferon-γ or supernatants derived from antigen-stimulated Th1 clones did not affect the production of sIL-4R by activated splenic cultures. Despite its correlation with Th2 responses, the presence of IL-4 was not an absolute requirement for the up-regulation of the expression of sIL-4R because increased levels could be induced on cells obtained from IL-4−/− mice. These results indicate that, although enhanced sIL-4R production is a feature related to the activation and/or generation of Th2 responses, it is not absolutely dependent on IL-4 or directly inhibited by IL-12 or Th1 cytokines. J. Leukoc. Biol. 66: 481–488; 1999.
Inhibition of fMLP-triggered respiratory burst of human monocytes by adenosine: involvement of A3 adenosine receptor
Authors: Broussas Matthieu , Cornillet-Lefèbvre Pascale , Potron Gérard , Nguyen Philippe
Published: January 2018

Adenosine (Ado) is a potent anti-inflammatory agent acting on a variety of cell functions. However, its effects on human monocytes have been less well characterized. We investigated the effect of Ado and its receptor-specific analogs on NADPH oxidase activity with the use of luminol-enhanced chemiluminescence (CL). Adenosine inhibited fMLP-triggered NADPH oxidase activity with a maximal inhibition of 55 ± 5%. IB-MECA, a selective A3 Ado receptor agonist reduced fMLP triggered NADPH oxidase activity more potently than the A2 receptor agonist CGS 2180 HCl (CGS) and the A1 Ado receptor agonist N-2-phenylethyladenosine (R-PIA). The inhibitory effect of Ado was reversed by neither the A1 Ado receptor antagonist 1,3-dipropyl-8(2-amino-4chlorophenyl)-xanthine (PACPX) nor the A2 Ado receptor antagonist 3,7-dimethyl-1-(2-propynyl)xanthine (DMPX). It was significantly reversed by the A1/A3 Ado receptor antagonist xanthine amine congener (XAC). Pretreatment of monocytes by cytochalasin B reversed the effect of Ado but not of dibutyryl cAMP (dBcAMP) on fMLP-CL response. KT 5720, a specific cAMP-dependent protein kinase inhibitor completely counteracted the inhibition of NADPH oxidase activity by dBcAMP but not by Ado. Using flow cytometry, we observed that Ado did not inhibit intracellular oxidative metabolism, whereas dBcAMP did. Furthermore, the inhibition of NADPH oxidase activity by Ado was not mediated by changes in cytosolic calcium. These results demonstrated that Ado inhibited NADPH oxidase activity via A3 Ado receptor independently of cAMP elevation or changes in calcium mobilization. J. Leukoc. Biol. 66: 495–501; 1999.
Polarized expression of immunoglobulin, spectrin, and protein kinase C beta II occurs in B cells from normal BALB/c, autoimmune lpr, and anti-ssDNA transgenic, tolerant mice
Authors: Masso-Welch Patricia A , Black Jennifer D , Erikson Jan , Repasky Elizabeth A
Published: January 2018

The rapid redistribution of B cell surface immunoglobulin to a cap upon cross-linking treatment is a well-described phenomenon, the physiological significance of which is unknown. We describe the observation that splenic B cells from unimmunized normal, autoimmune, and tolerant mice express naturally occurring capped immunoglobulin in the absence of exogenous stimulation. The percentage of capped B cells increases to 20% of B cells by age 16 weeks in the progressive autoimmune lpr mouse. Transgenic, tolerant mice expressing lpr-derived genes for ssDNA-binding antibody also demonstrate a large percentage (35–75%) of immunoglobulin-capped splenic B cells. In these capped B cells, protein kinase C beta II, the cytoskeletal proteins spectrin and ankyrin, and the lipophilic probe diI are enriched beneath the site of the immunoglobulin cap. These data suggest that polarization of surface receptors, signaling molecules, anionic phospholipid domains, and cytoskeletal proteins may be an important part of the B cell immune response in vivo. J. Leukoc. Biol. 66: 617–624; 1999.
The transcription factor PU.1 does not regulate lineage commitment but has lineage-specific effects
Authors: McKercher Scott R , Henkel Gregory W , Maki Richard A
Published: January 2018

PU.1 is a transcription factor shown to regulate the expression of many important genes in myeloid and B cells. At birth, mice homozygous for the disruption of the PU.1 gene have erythrocytes, megakaryocytes, and T cells, but no mature myeloid or B cells. Cells with an inability to develop to maturity were found in this mouse for B cells, neutrophils, eosinophils, mast cells, and monocytes. Rescue of early monocytic cells by transfection with the PU.1 gene results in renewed development to macrophages. These results demonstrate that PU.1 is an important regulator in the development of cells in the hematopoietic system. J. Leukoc. Biol. 66: 727–732; 1999.
Macrophage apoptosis in mycobacterial infections
Authors: Fratazzi Candida , Arbeit Robert D , Carini Claudio , Balcewicz-Sablinska M Kasia , Keane Joe , Kornfeld Hardy , Remold Heinz G
Published: January 2018

Mycobacterial diseases are a major public health concern. In the case of tuberculosis, the problem has been acerbated due to the emergence of drug-resistant strains of Mycobacterium tuberculosis, and Mycobacterium avium is the major opportunistic pathogen in HIV-1 infection in the United States. M. tuberculosis and M. avium replicate in human macrophages and induce apoptosis. Incubation of freshly added uninfected autologous macrophages with apoptotic M. avium-infected macrophages results in 90% inhibition of bacterial growth. Apoptosis also prevents the release of intracellular components and the spread of mycobacterial infection by sequestering the pathogens within apoptotic bodies. Consistent with the model that host cell apoptosis is a defense mechanism against mycobacteria is the finding that the virulent M. tuberculosis strain H37Rv induces substantially less macrophage apoptosis than the attenuated strain H37Ra. Evasion of apoptosis by this pathogen is achieved by enhanced release of sTNFR2 by H37Rv-infected macrophages and subsequent formation of inactive TNF-α-TNFR2 complexes. These observations contribute to the hypothesis that apoptosis of the host macrophage is an important defense mechanism in mycobacterial infections, which prevents the spread of the infection. J. Leukoc. Biol. 66: 763–764; 1999.
CpG-oligodeoxynucleotide-resistant variant of WEHI 231 cells
Authors: Manzel Lori , Macfarlane Donald E
Published: January 2018

Bacterial DNA and synthetic single-stranded oligonucleotides having unmethylated CpG motifs (CpG-ODN) powerfully stimulate cellular immune responses by an unknown mechanism. There is evidence that internalization of the nucleotide is required for activity. Both CpG-ODN and engagement of CD40 protects WEHI-231 murine B lymphoma cells from apoptosis induced by antibody to surface IgM, and both agents induce interleukin-6 (IL-6) production by these cells. We now report the isolation of CpG-ODN-resistant subclones (designated CR) from WEHI 231 cells, as well as subclones that are sensitive to CpG-ODN (designated CS). CR clones completely fail to respond to CpG-ODN but they retain the capacity to respond normally to engagement of CD40. CR cells incorporate CpG-ODN into small, acidified perinuclear vesicles in the same way as do the parent WEHI 231 cells. The CR, CS, and WEHI 231 cells all had identical cytogenetics. The described CR clones have a stable and specific defect in the mechanism responsible for the intracellular recognition and response to CpG-ODN, suggesting that they harbor a mutation that disables the CpG-ODN detection mechanism. These clones may be useful to determine at a molecular level which proteins and cell components are required for immune cells to detect and respond to CpG-ODN. J. Leukoc. Biol. 66: 817–821; 1999.
Ethanol-induced neutrophil apoptosis is mediated through nitric oxide
Authors: Singhal Pravin C , Patel Puja , Nàhàr Nilay , Franki Nicholas , Kapasi Aditi , Reddy Krishna , Shah Neena , Nwakoby Izuchukwu E , Mehrotra Bhoomi
Published: January 2018

Clinical reports indicate that acute ethanol intoxication in chronic ethanol abusers is associated with neutropenia. We hypothesize that ethanol accelerates the apoptosis of neutrophils thus decreasing the peripheral blood count of neutrophils. We studied the effect of ethanol on neutrophil apoptosis in vivo as well as in vitro. Human neutrophils harvested from healthy subjects after an alcohol drinking binge showed enhanced apoptosis (before, 0.5 ± 0.25 vs. after, 26.1 ± 2.6% apoptotic neutrophils/field). Peritoneal neutrophils isolated from ethanol-treated rats also showed increased (P < 0.0001) apoptosis when compared with neutrophils isolated from control rats (control, 0.8 ± 0.2% vs. ethanol, 11.8 ± 0.7% apoptotic neutrophils/field). In in vitro studies, ethanol in concentrations of 50 mM and higher accelerated the apoptosis of human and rat neutrophils. This effect of ethanol on human neutrophils was time dependent. DNA isolated from ethanol-treated human neutrophils displayed integer multiples of 180 base pairs (ladder pattern), further confirming the effect of ethanol on neutrophil apoptosis. NG-monomethyl-l-arginine monoac-etate and NG-nitro-L-arginine methyl ester, inhibitors of nitric oxide (NO) synthase, attenuated the ethanol-induced neutrophil apoptosis. Sodium nitroprusside, a NO donor, also promoted neutrophil apoptosis. Moreover, ethanol enhanced neutrophil expression of inducible NO synthase. In addition, ethanol stimulated neutrophil NO generation. These results suggest that ethanol accelerates neutrophil apoptosis. This effect of ethanol on neutrophil apoptosis seems to be mediated through the generation of NO. J. Leukoc. Biol. 66: 930–936; 1999.
Surface interleukin-10 inhibits listericidal activity by primary macrophages
Authors: Fleming Sherry D , Leenen Pieter J M , Freed John H , Campbell Priscilla A
Published: January 2018

Interleukin-10 (IL-10) down-regulates multiple functions of monocytes and macrophages, including the ability of macrophages to kill many intracellular microorganisms. The experiments presented here test the hypothesis that IL-10 expressed on the cell surface inhibits the ability of primary mouse macrophages to kill the facultative, intracellular bacterium Listeria monocytogenes. We show that, in contrast to macrophages from normal mice, both bone marrow-derived macrophages (BMDM) and thioglycollate-elicited macrophages obtained from IL-10−/− mice can kill L. monocytogenes. Treatment with anti-IL-10 monoclonal antibody (mAb) enables BMDM from normal mice and thioglycollate-elicited macrophages from RAG-2−/− mice (which lack T or B cell-derived IL-10) to kill L. monocytogenes, and concurrently down-regulates the expression of surface IL-10. Surface IL-10 on paraformaldehyde-fixed cells can inhibit nitric oxide (NO) production by interferon-γ (IFN-γ)-stimulated macrophages from IL-10−/− mice, thus directly showing functional activity of surface IL-10. Taken together, these studies indicate that macrophage surface IL-10 is biologically active and down-regulates macrophage bactericidal activity. J. Leukoc. Biol. 66: 961–967; 1999.
The murine chemokine receptor CXCR4 is tightly regulated during T cell development and activation
Authors: Schabath Richard , Müller Gerd , Schubel Andreas , Kremmer Elisabeth , Lipp Martin , Förster Reinhold
Published: January 2018

We have characterized the murine homolog of the HIV-co-receptor CXCR4 during T cell development and activation. Our data demonstrate that this chemokine receptor, although highly conserved between human and mouse, is differently expressed and regulated in both species. Mitogenic activation resulted in an increase of surface CXCR4 on murine T cells within 2 days, whereas the receptor was strongly down-regulated on human T cells during this period. Furthermore, intraperitoneal immunization of mice resulted in a strong increase of splenic and mesenteric cytotoxic T cells co-expressing CXCR4. It is interesting that, on thymocytes, expression of CXCR4 is restricted to CD4+CD8+ cells. Stromal cell-derived factor-1α, a natural ligand of CXCR4, induced chemotaxis of thymocytes and was found to counteract dexamethasone-induced apoptosis to a certain extent in these cells. Thus, our data show that expression of CXCR4 is tightly controlled on murine T cells and indicate that this highly conserved chemokine receptor might serve different functions in humans and mice. J. Leukoc. Biol. 66: 996–1004; 1999.
Interaction of various intracellular signaling mechanisms involved in mononuclear phagocyte toxicity toward neuronal cells
Authors: Klegeris Andis , McGeer Patrick L
Published: January 2018

Microglia become activated in a wide range of neurodegenerative disorders, including Alzheimer's disease. Such activation may lead to autodestruction of neurons. It is demonstrated here that activation of both human microglia and monocytic THP-1 cells by a combination of lipopolysaccharide and interferon-γ results in secretion of neurotoxins that kill human neuronal SH-SY5Y cells. This neurotoxicity can be partially blocked by inhibitors of cytosolic phospholipase A2, cGMP-selective phosphodiesterases, or protein kinase C. When combinations of these inhibitors, or combinations of an inhibitor plus nordihydroguaiaretic acid, or the nonsteroidal anti-inflammatory drug diclofenac were tried, additive reductions in neurotoxicity were observed. It is concluded that the stimulants activated multiple intracellular pathways, and that combination therapies inhibiting these pathways might be beneficial for treating neurodegenerative disorders. J. Leukoc. Biol. 67:127–133; 2000.
Bimodal role of endogenous interleukin-6 in concanavalin A-induced hepatitis in mice
Authors: Tagawa Yoh-ichi , Matthys Patrick , Heremans Hubertine , Dillen Chris , Zaman Zahur , Iwakura Yoichiro , Billiau Alfons
Published: January 2018

Acute concanavalin A (Con A)-induced hepatitis in mice is an animal model for hepatic injury induced by activated T cells. The evolution of hepatic involvement can be followed from hour to hour by measuring serum transaminase levels. We investigated the possible role of endogenous interleukin-6 (IL-6) in this model. We found serum IL-6 levels and splenic IL-6 mRNA during Con A-induced hepatitis to be significantly lower in interferon-γ (IFN-γ)-deficientmice, which are resistant against the Con A-induced syndrome, than in wild-type ones, suggesting that systemic IL-6 production favors development of hepatic injury. However, IL-6-deficient mice proved to be more susceptible to the disease than wild-type mice, indicating that endogenous IL-6 plays a predominantly hepatoprotective role. Experiments in which wild-type mice were treated with anti-IL-6 antibodies, before or after Con A challenge, allowed us to reconcile these contrasting observations. The antibody injections resulted in a biphasic alteration of serum IL-6 levels, initial neutralization being followed by rebound increased levels due to accumulation of IL-6 in the form of antigen-antibody complexes. The effect of antibody on disease severity differed depending on the time of injection. Antibody injection at 2.5 h post Con A resulted in delayed disease manifestation, whereas treatment initiated before Con A resulted in accelerated disease. We conclude that endogenous IL-6 plays a bimodal role. IL-6 present before Con A challenge as well as that induced in the very early phase after Con A injection triggers hepatoprotective pathways. Continuation of IL-6 production beyond this early phase, by some other pathway, seems to be harmful to hepato-cytes. J. Leukoc. Biol. 67: 90–96; 2000.M
AP-1 activity is negatively regulated by cannabinol through inhibition of its protein components, c-fos and c-jun
Authors: Faubert Barbara L , Kaminski Norbert E
Published: January 2018

Regulation of the activator protein-1 (AP-1) complex is very intricate because it involves phosphorylation state, protein-protein, and protein-DNA interactions. In these studies, the regulation of AP-1 activity, with emphasis on c-fos and c-jun regulation, was investigated using cannabinol (CBN) in primary mouse splenocytes in vitro. Cannabinoid compounds exhibit immunosuppressive actions that are putatively mediated through Gi-protein coupled receptors that negatively regulate adenylate cyclase. However, recent studies suggest that cannabi-noids modulate other signaling cascades. Indeed, we demonstrate that CBN inhibited binding to AP-1-containing sites from the interleukin-2 promoter. This inhibition of binding was, in part, due to decreased nuclear expression of c-fos and c-jun. We further determined that the effects of CBN were due to posttranslational modifications of these phosphoproteins and showed that CBN inhibited the activation of ERK MAP kinases. Thus, cannabinoid-induced immunosuppression involves disruption of the ERK signaling cascade. J. Leukoc. Biol. 67: 259–266; 2000.
The interleukin-1 receptor/Toll-like receptor superfamily: signal generators for pro-inflammatory interleukins and microbial products
Authors: Bowie Andrew , O'Neill Luke A J
Published: January 2018

The interleukin-1 (IL-1) receptor/Tolllike receptor (TLR) superfamily is a recently defined and expanding group of receptors that participate in host responses to injury and infection. The superfamily is defined by the Toll/IL-1 receptor (TIR) domain, which occurs in the cytosolic region of family members, and is further subdivided into two groups based on homology to either the Type I IL-1 receptor or Drosophila Toll receptor extracellular domain. The former group includes the receptor for the important Th1 cytokine IL-18, and T1/ST2, which may have a role in Th2 cell function. The latter group includes six mammalian TLRs, including TLR2 and TLR4, that largely mediate the host response to gram-positive and gram-negative bacteria, respectively. Whether bacterial products are actual ligands for TLRs, or whether they generate ligands via as yet unidentified pattern recognition receptors, has yet to be determined. Signaling pathways activated via the TIR domain trigger the activation of downstream kinases, and transcription factors such as NF-κB, and involve the adaptor protein MyD88, which itself contains a TIR domain. J. Leukoc. Biol. 67: 508–514; 2000.
Specific association of increased cyclin-dependent kinase 5 expression with monocytic lineage of differentiation of human leukemia HL60 cells
Authors: Chen Fei , Rao Jie , Studzinski George P
Published: January 2018

Hematopoietic cell differentiation takes place in phenotypically recognizable stages characterized by morphology as well as by the expression of enzymes and surface markers. It is recognized that differentiation results from an interaction of environmental cues, such as cytokines and hormones, with internal cellular programs, but the precise mechanisms are not entirely clear. HL60 cells, a human acute myeloid leukemia (AML) cell line with promyelocytic features, provide a model for such studies because they behave like stem cells, which can differentiate into two different lineages, granulocytic or monocytic/macrophage, depending on the inducer. Protein levels and kinase activity of cyclin-dependent kinase 5 (Cdk5) were reported [F. Chen and G. P. Studzinski (1999) Exp. Cell Res. 249, 422, 1999] to increase in HL60 cells induced to monocytic differentiation by 1α, 25-dihydroxyvitamin D3 (1,25D3), but the specificity of the association of Cdk5 with the monocytic phenotype has not been established. We show here that up-regulation of Cdk5 does not occur in granulocytic differentiation, whereas inhibition of Cdk5 activity by olomoucine, or its expression by a plasmid construct expressing antisense Cdk5, switches the 1,25D3-induced monocytic phenotype (a combination of positive nonspecific esterase reaction, expression of the CD14 marker, and morphology) to general myeloid phenotype (positive nitro-blue tetrazolium reaction, CD11b marker and morphology). The transcriptional up-regulation of Cdk5 by 1,25D3 was not inhibited by olomoucine. These findings show that in human myeloid cells up-regulation of Cdk5 is specifically associated with the monocytic phenotype. J. Leukoc. Biol. 67: 559–566; 2000.
Performance analysis of a digital fiber optic link incorporating gain‐levered laser diode transmitter
Authors: Piramasubramanian S. , Ganesh Madhan M. , Sindhuja A.
Published: January 2018

In this paper, digital modulation performance of two‐section, multiple quantum well gain‐levered laser diode in a fiber optic link is analyzed. This study involves numerical simulation of gain‐levered laser diode along with single‐mode fiber for evaluating gigabit rate digital transmission. The optical link performance is analyzed by evaluating the eye diagram, extinction ratio, and quality factor for different bit rates, modulation current, and fiber lengths. The results are compared with unlevered or normal laser diode–based fiber optic link with similar operating conditions. A 12‐dB improvement in extinction ratio is obtained for gain‐levered laser diode when the longer section and shorter section currents are kept as 30 and 0.5 mA, respectively. The Q parameter is found to increase with increasing modulation current in the gain‐levered case, and a maximum Q factor of 11 is obtained for a modulation current of 5 mA. The Q value is improved by a factor of 8 and 5 at 1‐ Gbps and 10‐Gbps data rates, respectively, under gain‐levered condition, when compared to normal laser diode–based link.
Synthesis of polydopamine‐functionalized magnetic graphene and carbon nanotubes hybrid nanocomposites as an adsorbent for the fast determination of 16 priority polycyclic aromatic hydrocarbons in aqueous samples
Authors: Chen Kun , Jin Rongrong , Luo Chen , Song Guoxin , Hu Yaoming , Cheng Hefa
Published: January 2018

A novel adsorbent made of polydopamine‐functionalized magnetic graphene and carbon nanotubes hybrid nanocomposite was synthesized and applied to determine 16 priority polycyclic aromatic hydrocarbons by magnetic solid phase extraction in water samples. FTIR spectroscopy, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy consistently indicate that the synthesized adsorbents are made of core–shell nanoparticles well dispersed on the surface of graphene and carbon nanotubes. The major factors affecting the extraction efficiency, including the pH value of samples, the amount of adsorbent, adsorption time and desorption time, type and volume of desorption solvent, were systematically optimized. Under the optimum extraction conditions, a linear response was obtained for polycyclic aromatic hydrocarbons between concentrations of 10 and 500 ng/L with the correlation coefficients ranging from 0.9958 to 0.9989, and the limits of detection (S/N = 3) were between 0.1 and 3.0 ng/L. Satisfactory results were also obtained when applying these magnetic graphene/carbon nanotubes/polydopamine hybrid nanocomposites to detect polycyclic aromatic hydrocarbons in several environmental aqueous samples.
Rapid characterization of chlorogenic acids in Duhaldea nervosa based on ultra‐high‐performance liquid chromatography–linear trap quadropole‐Orbitrap‐mass spectrometry and mass spectral trees similarity filter technique
Authors: Liu Lianghong , Zhang Jiayu , Zheng Binjie , Guan Ying , Wang Liting , Chen Lei , Cai Wei
Published: January 2018

Duhaldea nervosa (Wallich ex Candolle) A. Anderberg has been traditionally used as a food spice and also in folk medicine for treating traumatic injury and relieving rheumatism, especially accelerating the healing of a fracture. However, so far as we are aware, the chemical constituents have not been fully investigated. In this study, a practical method of mass spectral trees similarity filter, a data‐mining technique, was developed and evaluated for the rapid detection and identification complicated constituents based on ultra‐high‐performance liquid chromatography–linear trap quadropole‐Orbitrap‐mass spectrometry. Finally, a total of 47 chlorogenic acids, including 19 monoacyl‐quinic acids, 22 diacyl‐quinic acids, and six triacyl‐quinic acids, were unambiguously or tentatively identified based on their accurate mass measurement, chromatographic retention, MSn spectra, and bibliography data. To our best knowledge, it is the first time to report the chlorogenic acids of D. nervosa, which would be beneficial for the further material basis and quality research. Meanwhile, this mass spectral trees similarity filter method could be envisioned to exhibit a wide application for the identification of complicated components from botanical extracts.
Global qualitative analysis of a discrete host‐parasitoid model with refuge and strong Allee effects
Authors: Wu Daiyong , Zhao Hongyong
Published: January 2018

In this paper, we discuss the qualitative behavior of a discrete host‐parasitoid model with the host subject to refuge and strong Allee effects. More precisely, we study the local and global asymptotic stability, stable manifolds and unstable manifolds of boundary equilibrium points, existence and unique positive equilibrium point, local and global behavior of the positive equilibrium point, and the uniform persistence for the model with the host subject to the refuge or both refuge and strong Allee effects. It is also proved that the model undergoes a transcritical bifurcation in a small neighborhood of the boundary equilibrium point. Some numerical simulations are given to support our theoretical results. We can obtain that the addition of the refuge may make the parasitoids go extinct while the hosts survive or may stabilize the host‐parasitoid interaction; the addition of both refuge and strong Allee effects has either a negative or positive impact on the coexistence of both populations.
Dynamic coronary MR angiography in a pig model with hyperpolarized water
Authors: Lipsø Kasper Wigh , Hansen Esben Søvsø Szocska , Tougaard Rasmus Stilling , Laustsen Christoffer , Ardenkjær‐Larsen Jan Henrik
Published: January 2018

Purpose

To investigate dynamic coronary MR angiography using hyperpolarized water as a positive contrast agent. Hyperpolarization can increase the signal by several orders of magnitude, and has recently been translated to human cardiac application. The aim was to achieve large 1H signal enhancement to allow high‐resolution imaging of the coronary arteries.

Methods

Protons in D2O were hyperpolarized by dissolution dynamic nuclear polarization. A total of 18 mL of hyperpolarized water was injected into the coronary arteries of healthy pigs (N = 9; 3 injections in 3 animals). The MRI images were acquired with a gradient‐echo sequence in an oblique slab covering the main left coronary arteries with 0.55 mm in‐plane resolution. The acquisition time was 870 ms per frame.

Results

A more than 200‐fold signal enhancement compared with thermally polarized water at 3 T was obtained. Coronary angiographic images with a signal‐to‐noise ratio from the left main stem of 269 ± 169 and coronary sharpness from the proximal left anterior descending coronary artery of 0.31 ± 0.086 mm−1 were obtained. Dynamic images were acquired over a 10 s time window.

Conclusion

Hyperpolarized water MR angiography of the coronary arteries in a large animal model with high signal‐to‐noise ratio and high spatial and temporal resolution was obtained. Magn Reson Med 80:1165–1169, 2018. © 2018 International Society for Magnetic Resonance in Medicine.
Determinants of health care professional association members' intention to renew and recommend membership to others
Authors: Ki Eyun‐Jung
Published: January 2018

This study was designed to explore the determinants of membership retention and expansion within a health care professional association. Analyzing empirical data from 824 members of the largest and most internationally representative health care professional association, this study found membership dues value and member attitude toward the association are key predictors of the decisions to renew membership and recommend it to others, whereas membership drop experience was a negative predictor of the 2 behavioral outcomes regarding members. Personal benefits provided by membership in the association are a determinant of recommending membership to others but not a significant factor in renewing membership.
Preparation of mixed matrix membranes based on polyimide and aminated graphene oxide for CO2 separation
Authors: Ge Bao‐Sheng , Wang Tao , Sun Hai‐Xiang , Gao Wen , Zhao Hao‐Ru
Published: January 2018

The aminated graphene oxide (GO) was prepared by the functionalization of pristine GO with ethylenediamine and then dispersed into the poly(amic acid) (the precursor of polyimide [PI]) solution followed by the chemical imidization to successfully fabricate the PI/amine‐functionalized GO mixed matrix membranes (MMMs) using in‐situ polymerization method. Chemical structure and morphology of the GO before and after amine modification were characterized by scanning electron microscopy, Raman spectrum, Fourier transform infrared, and X‐ray photoelectron spectroscopy. Scanning electron microscopy indicated that fine dispersion of GO throughout PI matrix was achieved, which indicates that the in‐situ polymerization approach can enhance the interfacial interaction between the GO and the PI matrix, and then improve the dispersion of carbon material in the polymer matrix. Compared with the conventional solution mixture method, the MMMs prepared with in‐situ polymerization method showed excellent CO2 permeability and CO2/N2 selectivity. The MMMs doped with 3 wt.% aminated GO exhibited maximum gas separation performance with a CO2 permeability of 12.34 Barrer and a CO2/N2 selectivity of 38.56. These results suggest that the amino groups on GO have strong interaction with the CO2 molecules, which can significantly increase the solubility of polar gas. Our results provide an easy and efficient way to prepare MMMs with good mechanical behavior and excellent gas separation performance.
Reduced lysosomal clearance of autophagosomes promotes survival and colonization of Helicobacter pylori
Authors: Zhang Lin , Hu Wei , Cho Chi H , Chan Francis KL , Yu Jun , Fitzgerald J Ross , Cheung Cynthia KY , Xiao Zhan G , Shen Jing , Li Long F , Li Ming X , Wu Justin CY , Ling Thomas KW , Chan Jason YK , Ko Ho , Tse Gary , Ng Siew C , Yu Sidney , Wang Maggie HT , Gin Tony , Ashktorab Hassan , Smoot Duane T , Wong Sunny H , Chan Matthew TV , Wu William KK
Published: January 2018

Evasion of autophagy is key for intracellular survival of bacteria in host cells, but its involvement in persistent infection by Helicobacter pylori, a bacterium identified to invade gastric epithelial cells, remains obscure. The aim of this study was to functionally characterize the role of autophagy in H. pylori infection. Autophagy was assayed in H. pylori‐infected human gastric epithelium and the functional role of autophagy was determined via genetic or pharmacological ablation of autophagy in mouse and cell line models of H. pylori infection. Here, we showed that H. pylori inhibited lysosomal function and thereby promoted the accumulation of autophagosomes in gastric epithelial cells. Importantly, inhibiting autophagosome formation by pharmacological inhibitors or genetic ablation of BECN1 or ATG5 reduced H. pylori intracellular survival, whereas inhibition of lysosomal functions exerted an opposite effect. Further experiments demonstrated that H. pylori inhibited lysosomal acidification and the retrograde trafficking of mannose‐6‐phosphate receptors, both of which are known to positively regulate lysosomal function. We conclude that H. pylori subverts autophagy into a pro‐survival mechanism through inhibition of lysosomal clearance of autophagosomes. Disruption of autophagosome formation offers a novel strategy to reduce H. pylori colonization in human stomachs. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Thiol‐ene photofunctionalization of 1,4‐polymyrcene
Authors: Matic Aleksandar , Schlaad Helmut
Published: January 2018

1,4‐Polymyrcene was synthesized by anionic polymerization of β‐myrcene and was subjected to photochemical functionalization with various thiols (i.e. methyl thioglycolate, methyl 3‐mercaptopropionate, butyl 3‐mercaptopropionate, ethyl 2‐mercaptopropionate and 2‐methyl‐2‐propanethiol) using benzophenone/UV light as the radical source. The yield of thiol addition to the trisubstituted double bonds of 1,4‐polymyrcene decreased in the order 1° thiol (ca 95%) > 2° thiol (ca 80%) > 3° thiol (<5%), due to the reversibility of the thiol‐ene reaction. Remarkably, thiol addition to the side‐chain double bonds was 8 − 10 times (1° thiol) or 24 times (2° thiol) faster than to the main‐chain double bonds, which can be explained by the different accessibility of the double bonds and steric hindrance. Despite the use of a 10‐fold excess of thiol with respect to myrcene units, the thiol‐ene addition was accompanied by chain coupling reactions, which in the extreme case of 3° thiol (or in the absence of thiol) resulted in the formation of insoluble crosslinked material. As an example, a methyl‐thioglycolate‐functionalized 1,4‐polymyrcene was saponified/crosslinked to give submicron polyelectrolyte particles in dilute alkaline solution. © 2018 Society of Chemical Industry
Energy Back Transfer Induced Color Controllable Upconversion Emissions in La2MoO6:Er3+/Yb3+ Nanocrystals for Versatile Applications
Authors: Du Peng , Luo Laihui , Yu Jae Su
Published: January 2018

Color controllable Er3+/Yb3+‐codoped La2MoO6 upconverting nanocrystals are successfully synthesized via a facile sol‐gel method. Under the irradiation of 980 nm light, the entire samples exhibit dazzling upconversion (UC) emissions arising from the intra‐4f transitions of Er3+ ions and the UC emission intensity is strongly dependent on the Yb3+ ion concentration. Moreover, by controlling the Yb3+ ion concentration, the emission color is changed from green to yellow and finally to red as a result of the energy back transfer from Er3+ to Yb3+ ions, which is further verified by the theoretically discussion based on the steady‐state rate expressions. The optical thermometric properties of the prepared nanocrystals based on the (2H11/2,4S3/2) thermally coupled levels of Er3+ ions are systematically studied by analyzing the temperature‐dependent green UC emission spectra in the range of 303–663 K. The maximum sensor sensitivity of resultant nanocrystals is determined to be 0.0083 K−1 at 510 K. Furthermore, the emitting color of the synthesized nanocrystals relies on the temperature. In addition, the heating effect induced by the excitation pump power is also investigated and the host lattice temperature is enhanced from 319 to 404 K with raising the pump power from 159 to 757 mW.
Congenital central hypoventilation syndrome: Broader cognitive deficits revealed by parent controls
Authors: Zelko Frank A. , Stewart Tracey M. , Brogadir Cindy D. , Rand Casey M. , Weese‐Mayer Debra E.
Published: January 2018

Objective

To investigate neurocognitive deficits in children with Congenital Central Hypoventilation Syndrome (CCHS) by comparing them to their parents, since parents comprise a particularly suitable control group matched on disease‐extrinsic factors that can influence neurocognitive functioning. We compared CCHS patients to their parents and to population norms, hypothesizing that they would obtain lower intelligence test scores than both groups. We also compared patient‐parent differences against patient‐normative differences, to determine whether the two analytic approaches would yield different results.

Methods

We administered an intelligence screening, the Shipley‐2, to 21 school‐aged patients (age 14.2 ± 5.5 years) with PHOX2B mutation‐confirmed CCHS and their parents. Patients also received detailed clinical intellectual assessments using the Wechsler scales.

Results

CCHS patients scored significantly below parents on Shipley‐2 indices of intelligence, vocabulary, and abstraction, with a trend for perceptual reasoning. The CCHS patients scored significantly below population norms on indices of abstraction and perceptual reasoning. Patient‐parent differences were significantly larger than patient‐normative differences for vocabulary scores. CCHS patients scored significantly below population norms on Wechsler indices of intelligence, perceptual reasoning, working memory, and processing speed.

Conclusions

CCHS may affect a broader range of cognitive abilities than previous research based on comparisons to population norms has indicated. Comparisons of CCHS children to their parents reveal deficits of vocabulary and abstract reasoning which have not been previously identified. A full understanding of the neurocognitive impact of CCHS requires comparisons between patients and other individuals such as friends, parents, or siblings who closely resemble them on disease‐extrinsic characteristics.
Assessment of the dissipation, pre‐harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites in greenhouse cucumber (Cucumis sativus L.)
Authors: Geng Yue , Jiang Linjie , Zhang Yanwei , He Zeying , Wang Lu , Peng Yi , Wang Yuehua , Liu Xiaowei , Xu Yaping
Published: January 2018

BACKGROUND

The dissipation behavior, pre‐harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites were investigated in greenhouse cucumber in Tianjin, northern China, to ensure raw consumption safety.

RESULTS

Carbosulfan was metabolized to carbofuran, dibutylamine, 3‐hydroxycarbofuran and 3‐ketocarbofuran, and dimethoate was degraded to omethoate in cucumber fruits and leaves. The dissipation of carbosulfan, carbofuran, 3‐hydroxycarbofuran and dimethoate fitted first‐order kinetics well, with R2 ranging from 0.912 to 0.992, and their half‐lives were 2.6, 2.7, 2.4 and 5.2 days in cucumber fruits and 2.8, 3.0, 4.6 and 2.5 days in leaves, respectively. The estimated daily intakes of the active ingredients and their relevant metabolites were 0.1–4% of the corresponding acceptable daily intakes. Acute oral exposure to carbofuran (a metabolite of carbosulfan) represented 367% of the acute reference dose (ARfD) for 1–6‐year‐old Chinese children and 227% for the general Chinese population.

CONCLUSION

A minimum pre‐harvest interval of 12 days for carbosulfan is proposed to ensure safe consumption of cucumber. The slow dissipation rate of omethoate in cucumber reveals that a longer pre‐harvest interval (≥ 27 days) is necessary to prevent dietary risk when dimethoate is applied to cucumber. © 2018 Society of Chemical Industry
Investigation of molar concentration effect on structural, optical, electrical, and photovoltaic properties of spray‐coated Cu2O thin films
Authors: David Prabu R. , Valanarasu S. , Ganesh V. , Shkir Mohd , AlFaify S. , Kathalingam A.
Published: January 2018

High quality copper oxide thin films were prepared by nebulizer spray pyrolysis technique using different concentrations of copper precursor solution. Concentration‐dependent structural, morphological, optical, and electrical properties of the prepared films are discussed. X‐ray diffraction studies done for the samples confirmed that the deposited films are in Cu2O phase with polycrystalline cubic structure. Atomic force microscopy analysis revealed that all the films are composed of nano sheet shaped grains covering the substrate surface. Optical studies done on the samples showed band gap values 2.42, 2.31, and 2.02 eV for the solution concentration 0.01, 0.05, and 0.1 M, respectively. Photoluminescence spectral analysis showed the emission band at 620 nm confirming the formation of cuprous oxide. Electrical analysis of the films showed p‐type conductivity with a low resistivity 2.19 × 102 Ω.cm and high carrier concentration 16.76 × 10 15 cm−3 for the molar concentration 0.1 M. In this work, Cu2O/ZnO heterojunctions were also prepared, and solar cell properties were studied; they were found to show increased open circuit voltage and short circuit current for higher copper concentration.
Functionalization of zwitterionic polymer brushes, do they remain antifouling?
Authors: Hakobyan Shoghik , Rzhepishevska Olena , Barbero David R. , Ramstedt Madeleine
Published: January 2018

Polymer brushes are surface coatings that can be tailored in many ways to suit specific demands including reduction of protein and bacterial fouling of biomaterials. Previously, we reported that antifouling poly (2‐(methacryloxy)ethyl)dimethyl‐3‐sulphopropyl ammonium hydroxide) brushes dramatically reduced formation of bacterial biofilm. We hypothesized that: (1) this brush could be efficiently functionalized with a small molecule (2‐oxo‐2‐[N‐(2,4,6‐trihydroxybenzylidene)‐hydrazino]‐acetamide, ME0163, hydrazone) and that (2) the antifouling property would remain also after functionalization. Diblock co‐polymer brushes of 2‐(methacryloxy)ethyl)dimethyl‐3‐sulphopropyl ammonium hydroxide and poly (glycidyl methacrylate) were formed by surface‐initiated atom transfer radical polymerization (SI‐ATRP), and the ME0163 hydrazone was covalently bound to the surface via a ring‐opening reaction. Functionalization of the surfaces was followed by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV‐Vis spectroscopy. The influence of temperature, reaction time, and reagent concentrations on the immobilization process was investigated. Surfaces with high degree of functionalization could be made in this way. However, the functionalization rendered the surface more hydrophobic, and the antifouling property of the brush was lost, thus, disproving the second of our starting hypotheses but corroborating the first.