bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Acetic Acid and Glycerol in the Synthesis of Amorphous MgO Aerogels
Authors: Dong Winny , Yen Shiao‐Pin , Paik Jong‐Ah , Sakamoto Jeff
Published: May 2009

Although sol–gel‐derived magnesium‐oxide (MgO) aerogels have a wide variety of applications, mostly thin films and powders of brucite, i.e. Mg(OH)2 aerogels, have been reported. Typically, the brucite structure is converted to the periclase form of MgO upon heat‐treatment. We report the role of acetic acid (HAc) and glycerol in the synthesis of amorphous MgO aerogel monoliths through the alkoxide sol–gel method. The two ligands work in concert to retard the nucleophilic substitution with water and decrease the rate of gelation, allowing for Mg–O bond formation while reducing the number of hydroxyl bonds. The amorphous material crystallizes to the periclase (MgO) phase at 400°C without going through the brucite transition, resulting in a novel amorphous MgO aerogel. Specifically, we discuss the modification of the Pechini process to an Mg‐alkoxide sol–gel process. The roles of the ligands are investigated in the MgO gelation process through Fourier transform infrared spectroscopy, X‐ray diffractometry, and thermogravimetric analysis/DSC. The physical properties of the aerogels are also reported.
Improved Energy Storage Performance and Fatigue Endurance of Sr‐Doped PbZrO3 Antiferroelectric Thin Films
Authors: Hao Xihong , Zhai Jiwei , Yao Xi
Published: May 2009

Sr‐doped PbZrO3 antiferroelectric (AFE) thin films have been fabricated on the platinum‐buffered silicon substrates via the sol–gel technique. The temperature‐dependent dielectric properties results indicated that the AFE phase was stabilized for the Sr‐modified PbZrO3 thin films with a Curie temperature of 251°C. The recoverable energy density and energy efficiency of the Sr‐doped PbZrO3 thin films were enhanced by the doping of strontium. Compared with the pure PbZrO3 AFE thin films, the performance against fatigue of the Sr‐doped PbZrO3 thin films were also improved greatly.
Electron Magnetic Resonance Investigation of Gadolinium Diffusion in Ceria Powders
Authors: De Biasi Ronaldo S. , Grillo Maria L. N.
Published: May 2009

The electron magnetic resonance (EMR) technique was used to investigate the diffusion of gadolinium in ceria (CeO2) powders. The EMR absorption intensity was measured for several annealing times and three different temperatures of isothermal annealing: 1273, 1323, and 1373 K. The activation temperature for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be EA=485±5 kJ/mol. This value is very close to the one obtained for the diffusion of gadolinium in an oxide with a similar crystal structure, UO2, using the secondary ion mass spectrometry technique, EA=492 kJ/mol. On the other hand, it is much larger than the one obtained for the diffusion of gadolinium in yttrium vanadate (YVO4), EA=177 kJ/mol, a compound with a different crystal structure.
Transmission Electron Microscopy Characterization of Hot‐Pressed ZrB2 with MoSi2 Additive
Authors: Mizuguchi Takashi , Guo Shu‐Qi , Kagawa Yutaka
Published: May 2009

Microstructure of the hot‐pressed ZrB2 with MoSi2 additive was investigated by transmission electron microscopy (TEM). The effect of MoSi2 addition on the microstructure of the ceramic was assessed. For the pure ZrB2, the microstructure consisted of the equiaxed ZrB2 grains and a few elongated ZrB2 grains. For the ZrB2 with MoSi2 additive, the microstructure consisted almost entirely of equiaxed ZrB2 grains. A few dislocations were present in the ZrB2 grains. In addition, high‐resolution TEM observations showed that the intergranular amorphous phase was absent at two ZrB2 grain boundaries in the ZrB2 with MoSi2 additive.
Reproductive performance of little penguinsEudyptula minorin relation to year, age, pair‐bond duration, breeding date and individual quality
Authors: Nisbet Ian C. T. , Dann Peter
Published: May 2009

We measured breeding performance of little penguinsEudyptula minorat Phillip Island, Victoria, Australia, during a 21‐year period. All birds considered in this paper (n=307) were of known age (2–22 y) and sex, and most were of known, or closely‐estimated, pair‐bond status (1–8 mates per bird; pair‐bond durations 1–13 y). Breeding dates and breeding performance varied markedly from year to year; measures of annual performance were not associated with early breeding. Measures of individual breeding performance (clutch‐size, hatching success, chick masses and productivity) were related to early laying, parental age, and duration of pair‐bond. Dependence of breeding performance on parental age was curvilinear, levelling off at about 8 y of age. Productivity declined significantly among birds older than 8 y; this decline was not due to events in the last year of breeding (“terminal illness”). Breeding performance increased with duration of pair‐bond at least through y 5. Early breeding was significantly related to age and duration of pair‐bond. Most of these relationships were stronger among males than among females, and many of them were not significant when females were considered alone. After controlling for other factors, breeding performance varied significantly among birds, but autocorrelations were low and limited to intervals of one year. Parental quality (defined for birds studied in six or more years as the individual bird term in a GLM for productivity controlling for other factors) was not correlated with lifespan or other demographic parameters, but high‐quality birds were less prone to change mates and burrows than low‐quality birds. We know of no previous study in which simultaneous effects of laying date, age and pair‐bond duration on breeding performance were measured, while controlling for year, individual quality and terminal illness.
Implant stability during osseointegration in irradiated and non‐irradiated minipig alveolar bone: an experimental study
Authors: Verdonck Henk W. D. , Meijer Gert J. , Laurin Thorsten , Nieman Fred H. , Stoll Christian , Riediger Dieter , Stoelinga Paul J. W. , Baat Cees de
Published: May 2009

Objectives: Primary implant stability is related to local bone density. After insertion of an implant, implant stability is subject to changes due to bone remodeling. In patients who have undergone radiotherapy in the head and neck region, implant stability is impaired because irradiation reduces bone vitality. The current study was designed to monitor and test implant stability immediately after implant placement and during osseointegration in irradiated and non‐irradiated minipig alveolar bone.

Materials and methods: All maxillary and mandibular premolars and molars of six adult Göttingen minipigs were extracted. The maxilla and mandible of three minipigs received three irradiation exposures at a total dose of 24 Gy. After irradiation, five initial implant holes were drilled in the residual alveolar ridge of each edentulous site. In order to assess bone vascularity, laser Doppler flowmetry recordings were carried out in the initial holes. A total of 120 implants were placed in the six minipigs. Subsequently, and at 8, 16, and 24 weeks after implant placement, implant stability was recorded by resonance frequency analysis (RFA). RFA values were expressed as an implant stability quotient (ISQ).

Results: ISQ values recorded immediately after implant placement showed no differences between irradiated and non‐irradiated minipigs. Repeated measurements at the four recording moments showed a decrease of ISQ values in all minipigs, being more pronounced in irradiated bone, when compared with non‐irradiated bone. The results at the third and fourth recording moments showed a stabilization or even a slight increase of ISQ values.

Conclusions: The results document the negative effect of irradiation on bone vascularity and hence on implant stability.
A systematic review of the survival and complication rates of resin‐bonded bridges after an observation period of at least 5 years
Authors: Pjetursson Bjarni E. , Tan Wah Ching , Tan Ken , Brägger Urs , Zwahlen Marcel , Lang Niklaus P.
Published: May 2009

Objectives: The objectives of this systematic review were to assess the 5‐year survival of resin‐bonded bridges (RBBs) and to describe the incidence of technical and biological complications.

Methods: An electronic Medline search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on RBBs with a mean follow‐up time of at least 5 years. Patients had to have been examined clinically at the follow‐up visit. Assessment of the identified studies and data extraction were performed independently by two reviewers. Failure and complication rates were analyzed using random‐effects Poissons regression models to obtain summary estimates of 5‐year proportions.

Results: The search provided 6110 titles and 214 abstracts. Full‐text analysis was performed for 93 articles, resulting in 17 studies that met the inclusion criteria. Meta‐analysis of these studies indicated an estimated survival of RBBs of 87.7% (95% confidence interval (CI): 81.6–91.9%) after 5 years. The most frequent complication was debonding (loss of retention), which occurred in 19.2% (95% CI: 13.8–26.3%) of RBBs over an observation period of 5 years. The annual debonding rate for RBBs placed on posterior teeth (5.03%) tended to be higher than that for anterior‐placed RBBs (3.05%). This difference, however, did not reach statistical significance (P=0.157). Biological complications, like caries on abutments and RBBs lost due to periodontitis, occurred in 1.5% of abutments and 2.1% of RBBs, respectively.

Conclusion: Despite the high survival rate of RBBs, technical complications like debonding are frequent. This in turn means that a substantial amount of extra chair time may be needed following the incorporation of RBBs. There is thus an urgent need for studies with a follow‐up time of 10 years or more, to evaluate the long‐term outcomes.
Outpatient management of asthma in children age 5–11 years: Guidelines for practice
Authors: Watts Barbara
Published: May 2009

Purpose: To increase awareness among nurse practitioners (NPs) regarding diagnostic and treatment guidelines for asthma for the 5–11 year age group recently updated by the National Asthma Education Prevention Program‐Expert Panel 3 (NAEPP‐EPR3).

Data sources: NAEPP‐EPR3 guidelines for the diagnosis and management of asthma released from the National Heart, Lung, and Blood Institute in August 2007, selected clinical trials, meta‐analyses, and clinical reviews.

Conclusions: Recent research has revealed that children suffering from asthma in the United States are underdiagnosed and their asthma is poorly controlled. Compelling evidence supports that children classified as having persistent asthma following NAEPP‐EPR3 guidelines benefit from daily inhaled corticosteroid therapy, yet many are misclassified and undertreated.

Implications for practice: With application of current guidelines from NAEPP‐EPR3, NPs can more effectively assess, diagnose, treat, and foster a collaborative self‐management plan for children age 5–11 years. These interventions will result in an improved quality of life and decreased health risks for this young population.
Pierson v. Post: A Great Debate, James Kent, and the Project of Building a Learned Law for New York State
Authors: Fernandez Angela
Published: May 2009

Pierson v. Post(1805) has long puzzled legal teachers and scholars. This article argues that the appellate report was the product of the intellectual interests (and schooling) of the lawyers and judges involved in the case. They converted a minor dispute about a fox into a major argument in order to argue from Roman and other civil law sources on how to establish possession in wild animals, effectively crafting an opportunity to create new law for New York State. This article explores the possibility that the mastermind behind this case was the chief justice of the court at the time, James Kent. The question of Kent's involvement in 1805 remains elusive. However, the article uses annotations he made on his copy of the case and discussion ofPierson v. Postin his famousCommentariesto demonstrate the nature of his later interest and to explore the project of building a learned law for New York State.
Guardians at the Gate: The Backgrounds, Career Paths, and Professional Development of Private US Immigration Lawyers
Authors: Levin Leslie C.
Published: May 2009

This article presents findings from a qualitative study of seventy‐one New York immigration lawyers who are engaged in private practice. It focuses on the lawyers' backgrounds, career paths, and early professional training and describes, inter alia, the unusual diversity of this bar, the lawyers' reasons for practicing immigration law, the ways in which they learn to practice law, and the strong sense of community within the private immigration bar. It uses the idea of communities of practice to help understand how lawyers learn from their colleagues and are influenced by them. The article identifies several factors that may contribute to the supportiveness of the bar and the strong sense of community within that practice specialty, notwithstanding its great diversity. It concludes by making some preliminary comparisons between immigration lawyers and lawyers in other practice specialties and by identifying some questions for future study.
The evolutionarily conserved residue A653 plays a key role in HERG channel closing
Authors: Stepanovic Svetlana Z. , Potet Franck , Petersen Christina I. , Smith Jarrod A. , Meiler Jens , Balser Jeffrey R. , Kupershmidt Sabina
Published: May 2009

Humanether‐a‐go‐go‐related gene (HERG) encodes the rapid, outwardly rectifying K+currentIKrthat is critical for repolarization of the cardiac action potential. CongenitalHERGmutations or unintended pharmaceutical block ofIKrcan lead to life‐threatening arrhythmias. Here, we assess the functional role of the alanine at position 653 (HERG‐A653) that is highly conserved among evolutionarily divergent K+channels. HERG‐A653 is close to the ‘glycine hinge’ implicated in K+channel opening, and is flanked by tyrosine 652 and phenylalanine 656, which contribute to the drug binding site. We substituted an array of seven (I, C, S, G, Y, V and T) amino acids at position 653 and expressed individual variants in heterologous systems to assess changes in gating and drug binding. Substitution of A653 resulted in negative shifts of theV1/2of activation ranging from −23.6 (A653S) to −62.5 (A653V) compared to −11.2 mV for wild‐type (WT). Deactivation was also drastically altered: channels with A653I/C substitutions exhibited delayed deactivation in response to test potentials above the activation threshold, while A653S/G/Y/V/T failed to deactivate under those conditions and required hyperpolarization and prolonged holding potentials at −130 mV. While A653S/G/T/Y variants showed decreased sensitivity to theIKrinhibitor dofetilide, these changes could not be correlated with defects in channel closure. Homology modelling suggests that in the closed state, A653 forms tight contacts with several residues from the neighbouring subunit in the tetramer, playing a key role in S6 helix packing at the narrowest part of the vestibule. Our study suggests that A653 plays an important functional role in the outwardly rectifying gating behaviour of HERG, supporting channel closure at membrane potentials negative to the channel activation threshold.
Dispersion of the Excitations of Fractional Quantum Hall States
Authors: Kukushkin Igor V. , Smet Jurgen H. , Scarola Vito W. , Umansky Vladimir , von Klitzing Klaus
Published: May 2009

Getting Below the Surface

Two-dimensional electron systems have proved to be a productive area for the study of low-dimensional transport. Despite decades of intense effort, the actual dispersion of the electronic excitations—how their energy behaves as a function of momentum as the they move through their two-dimensional space—have eluded experiments. This elusiveness is due to the samples being thin and buried.

Kukushkin
et al.

(p. 1044; published online 30 April; see the Perspective by
Simon
) now introduce a technique based on launching surface acoustic waves through the sample. The excitations “ride” these waves, with their energy and momentum mapped out using pulses of laser light. The technique should also be applicable to other hard-to-get-at electronic systems.
Induction of Tumor Necrosis Factor Alpha and Interleukin-8 Gene Expression in Bronchial Epithelial Cells by Toxic Shock Syndrome Toxin 1
Authors: Aubert Vincent , Schneeberger Dominik , Sauty Alain , Winter Judith , Sperisen Peter , Aubert John-David , Spertini François
Published: May 2009

Major histocompatibility complex (MHC) class II engagement by toxic shock syndrome toxin 1 (TSST-1) transduces signals leading to proinflammatory cytokine gene expression (tumor necrosis factor alpha [TNF-α]) in human monocytes. To study the proinflammatory role of MHC class II molecules expressed by bronchial epithelial cells (BEC), primary human BEC were isolated from surgical bronchial samples, expanded in vitro, and cultured in the presence or absence of gamma interferon (IFN-γ) for 48 h.125I-TSST-1 binding to BEC pretreated with IFN-γ was inhibited up to 97% by anti-MHC class II monoclonal antibody 3B12, indicating that in BEC also MHC class II molecules were targets for the staphylococcal exotoxin. As analyzed by a quantitative reverse transcriptase PCR, a 1-h stimulation of BEC with TSST-1 resulted in a vigorous expression of TNF-α and interleukin-8 (IL-8) genes. TNF-α and IL-8 expression was optimal in BEC pretreated with 50 IU of IFN-γ/ml, whereas TSST-1 stimulation of BEC pretreated with 200 IU of IFN-γ/ml failed to enhance either TNF-α or IL-8 transcripts. In a time course study, peak expression of TNF-α and IL-8 mRNA was reached 6 h after TSST-1 stimulation. These results demonstrate that bacterial superantigen TSST-1 binds to MHC molecules on BEC and induces TNF-α and IL-8 gene expression upon engagement of MHC class II molecules on BEC, thus contributing to the perpetuation of bronchial mucosa inflammation via chemokine or cytokine gene expression.
Additive Attenuation of Virulence of
Streptococcus pneumoniae
by Mutation of the Genes Encoding Pneumolysin and Other Putative Pneumococcal Virulence Proteins
Authors: Berry Anne M. , Paton James C.
Published: May 2009

Although the polysaccharide capsule of
Streptococcus pneumoniae
has been recognized as a sine qua non of virulence, much recent attention has focused on the role of pneumococcal proteins in pathogenesis, particularly in view of their potential as vaccine antigens. The individual contributions of pneumolysin (Ply), the major neuraminidase (NanA), autolysin (LytA), hyaluronidase (Hyl), pneumococcal surface protein A (PspA), and choline-binding protein A (CbpA) have been examined by specifically mutagenizing the respective genes in the pneumococcal chromosome and comparing the impact on virulence in a mouse intraperitoneal challenge model. Mutagenesis of either the
ply
,
lytA
, or
pspA
gene in
S. pneumoniae
D39 significantly reduced virulence, relative to that of the wild-type strain, indicating that the respective gene products contribute to pathogenesis. On the other hand, mutations in
nanA
,
hyl
, or
cbpA
had no significant impact. The virulence of D39 derivatives carrying a
ply
deletion mutation as well as an insertion-duplication mutation in one of the other genes was also examined. Mutagenesis of either
nanA
or
lytA
did not result in an additional attenuation of virulence in the
ply
deletion background. However, significant additive attenuation in virulence was observed for the strains with
ply-hyl
,
ply-pspA
, and
ply-cbpA
double mutations.
T-Cell-Dependent Control of AcuteGiardia lambliaInfections in Mice
Authors: Singer Steven M. , Nash Theodore E.
Published: May 2009

We have studied immune mechanisms responsible for control of acuteGiardia lambliaandGiardia murisinfections in adult mice. Association of chronicG. lambliainfection with hypogammaglobulinemia and experimental infections of mice withG. murishave led to the hypothesis that antibodies are required to control these infections. We directly tested this hypothesis by infecting B-cell-deficient mice with eitherG. lambliaorG. muris. Both wild-type mice and B-cell-deficient mice eliminated the vast majority of parasites between 1 and 2 weeks postinfection withG. lamblia. G. muriswas also eliminated in both wild-type and B-cell-deficient mice. In contrast, T-cell-deficient andscidmice failed to controlG. lambliainfections, as has been shown previously forG. muris. Treatment of wild-type or B-cell-deficient mice with antibodies to CD4 also prevented elimination ofG. lamblia, confirming a role for T cells in controlling infections. By infecting mice deficient in either αβ- or γδ-T-cell receptor (TCR)-expressing T cells, we show that the αβ-TCR-expressing T cells are required to control parasites but that the γδ-TCR-expressing T cells are not. Finally, infections in mice deficient in production of gamma interferon or interleukin 4 (IL-4) and mice deficient in responding to IL-4 and IL-13 revealed that neither the Th1 nor the Th2 subset is absolutely required for protection fromG. lamblia. We conclude that a T-cell-dependent mechanism is essential for controlling acuteGiardiainfections and that this mechanism is independent of antibody and B cells.
Cytotoxic T-Lymphocyte Epitopes for HLA-B53 and Other HLA Types in the Malaria Vaccine Candidate Liver-Stage Antigen 3
Authors: Aidoo Michael , Lalvani Ajit , Gilbert Sarah C. , Hu Jiang Ting , Daubersies Pierre , Hurt Nicole , Whittle Hilton C. , Druihle Pierre , Hill Adrian V. S.
Published: May 2009

The development of an effective preerythrocytic vaccine againstPlasmodium falciparummalaria is likely to require inclusion of components from several preerythrocytic antigens. The association of HLA-B53 with resistance to severe malaria in West Africa provided evidence that HLA class I-restricted CD8+T-cell responses play a role in protective immunity in African children, supporting data from rodent models of malaria. Previously, a single epitope from liver-stage-specific antigen 1 (LSA-1) has been shown to be recognized by HLA-B53-specific cytotoxic T lymphocytes (CTL), but HLA-B53 epitopes were not found in four other antigens. In this study we measured CTL responses to peptides from the recently sequenced antigen liver-stage antigen 3 (LSA-3) and identified in it a new epitope restricted by HLA-B53. Several CTL epitopes restricted by other class I types were also identified within LSA-3 in studies in The Gambia and Tanzania. CTL were also identified to an additionalP. falciparumantigen, exported protein 1 (Exp-1), the homologue of which is a protective antigen in a rodent model of malaria. These findings emphasize the diversity ofP. falciparumantigens recognized by CD8+T cells in humans and support the inclusion of components from several antigens in new CTL-inducing vaccines against malaria.
Effects of Opsonization and Gamma Interferon on Growth ofBrucella melitensis16M in Mouse Peritoneal Macrophages In Vitro
Authors: Eze Michael O. , Yuan Liang , Crawford Robert M. , Paranavitana Chrysanthi M. , Hadfield Ted L. , Bhattacharjee Apurba K. , Warren Richard L. , Hoover David L.
Published: May 2009

Entry of opsonized pathogens into phagocytes may benefit or, paradoxically, harm the host. Opsonization may trigger antimicrobial mechanisms such as reactive oxygen or nitric oxide (NO) production but may also provide a safe haven for intracellular replication. Brucellae are natural intramacrophage pathogens of rodents, ruminants, dogs, marine mammals, and humans. We evaluated the role of opsonins inBrucella-macrophage interactions by challenging cultured murine peritoneal macrophages withBrucella melitensis16M treated with complement- and/or antibody-rich serum. Mouse serum rich in antibody againstBrucellalipopolysaccharide (LPS) (aLPS) and human complement-rich serum (HCS) each enhanced the macrophage uptake of brucellae. Combinations of suboptimal levels of aLPS (0.01%) and HCS (2%) synergistically enhanced uptake. The intracellular fate of ingested bacteria was evaluated with an optimal concentration of gentamicin (2 μg/ml) to control extracellular growth but not kill intracellular bacteria. Bacteria opsonized with aLPS and/or HCS grew equally well inside macrophages in the absence of gamma interferon (IFN-γ). Macrophage activation with IFN-γ inhibited replication of both opsonized and nonopsonized brucellae but was less effective in inhibiting replication of nonopsonized bacteria. IFN-γ treatment of macrophages with opsonized or nonopsonized bacteria enhanced NO production, which was blocked byNG-monomethyll-arginine (MMLA), an NO synthesis inhibitor. MMLA also partially blocked IFN-γ-mediated bacterial growth inhibition. These studies suggest that primary murine macrophages have limited ability to control infection withB. melitensis, even when activated by IFN-γ in the presence of highly opsonic concentrations of antibody and complement. Additional cellular immune responses, e.g., those mediated by cytotoxic T cells, may play more important roles in the control of murine brucellosis.
Roles of Endogenous Gamma Interferon and Macrophage Microbicidal Mechanisms in Host Response to Chemotherapy in Experimental Visceral Leishmaniasis
Authors: Murray Henry W. , Delph-Etienne Sharmaine
Published: May 2009

In experimental visceral leishmaniasis, in which the tissue macrophage is the target, in vivo responsiveness to conventional chemotherapy (pentavalent antimony [Sb]) requires a T-cell-dependent mechanism. To determine if this mechanism involves gamma interferon (IFN-γ)-induced activation and/or specific IFN-γ-regulated macrophage leishmanicidal mechanisms (generation of reactive nitrogen or oxygen intermediates, we treated gene-deficient mice infected withLeishmania donovani. In IFN-γ gene knockout (GKO) mice, Sb inhibited but did not kill intracellularL. donovani(2% killing versus 76% in controls). Sb was active (>94% killing), however, in both inducible nitric oxide synthase (iNOS) knockout (KO) and respiratory burst (phagocyte oxidase)-deficient chronic granulomatous disease (X-CGD) mice. Sb's efficacy was also maintained in doubly deficient animals (X-CGD mice treated with an iNOS inhibitor). In contrast to Sb, amphotericin B (AmB) induced high-level killing in GKO mice; AmB was also fully active in iNOS KO and X-CGD animals. Although resolution ofL. donovaniinfection requires iNOS, residual visceral infection remained largely suppressed in iNOS KO mice treated with Sb or AmB. These results indicate that endogenous IFN-γ regulates the leishmanicidal response to Sb and achieves this effect via a pathway unrelated to the macrophage's primary microbicidal mechanisms. The role of IFN-γ is selective, since it is not a cofactor in the response to AmB. Treatment with either Sb or AmB permits an iNOS-independent mechanism to emerge and control residual intracellularL. donovaniinfection.
M-Like Proteins ofStreptococcus dysgalactiae
Authors: Vasi József , Frykberg Lars , Carlsson Lena E. , Lindberg Martin , Guss Bengt
Published: May 2009

Streptococcus dysgalactiaeis one of the most important bacterial species isolated from bovine mastitis. To identify potential virulence factors of this species we prepared chromosomal DNA from strain 8215 and constructed a phage display library. By affinity selection of the library against fibrinogen (Fg), we isolated and characterized a gene, calleddemA, encoding a protein with the molecular mass of ∼58 kDa, called DemA, displaying both plasma protein binding properties and sequence similarities with the M and M-like proteins of other streptococcal species. Purified recombinant DemA protein was found to completely inhibit Fg-binding to cells ofS. dysgalactiae. A continued sequence analysis revealed that thedemAgene was preceded by an open reading frame (dmgA) coding for a putative protein, called DmgA, with high similarities to the Mga proteins ofStreptococcus pyogenes. By additional cloning, the correspondingdmgAanddemAgenes from another strain, called Epi9, were isolated and analyzed. These genes, calleddmgBanddemB, respectively, revealed a high degree of similarity to the corresponding genes in strain 8215. Increased binding of Fg by cells of strain Epi9, grown in an atmosphere with 10% CO2, was correlated to an enhanced transcription of thedemBgene as shown in a Northern blot. Strain 8215 did not respond to CO2, which could be explained by a nonfunctionaldmgAgene due to insertion of an insertion sequence element. Based on sequence similarities of the described proteins to Mga, M, and M-like proteins and the response to elevated level of CO2, we suggest that thedmganddemgenes are members of a regulon similar to the describedmgaregulon inS. pyogenes, which encodes several virulence factors in this species.
Seroreactivity toChlamydia trachomatisHsp10 Correlates with Severity of Human Genital Tract Disease
Authors: LaVerda David , Albanese Lisa N. , Ruther Paul E. , Morrison Sandra G. , Morrison Richard P. , Ault Kevin A. , Byrne Gerald I.
Published: May 2009

We have identified the chlamydial heat shock protein Hsp10 as a potential correlate to the immunopathogenic process in women with tubal factor infertility (TFI). The human serologic response to chlamydial Hsp10, Hsp60, and major outer membrane protein (MOMP) was measured by enzyme-linked immunosorbent assay. Three populations of women were studied: uninfected controls (CU), acutely infected (AI) women, and women with TFI. Sera from women in the AI and TFI groups both recognized Hsp10 more frequently and at a higher overall level than sera from healthy uninfected controls. Moreover, the infertile women had significantly greater Hsp10 seroreactivity than acutely infected women, indicating a concomitant increase of Hsp10 recognition in populations with increasing levels of disease severity. Hsp60 reactivity showed a similar correlation in these populations, while MOMP reactivity peaked at the same level in both AI and TFI populations but did not increase with disease severity. Test populations were standardized by level of reactivity to formalin-fixedChlamydia trachomatiselementary bodies (EBs) to address whether these associations were reflections of increased overall chlamydial exposure rather than a property specific to Hsp10. Associations between Hsp10 seropositivity and TFI were greater in the EB+subgroup while associations among the EB−subgroup were diminished. When restricted to the EB+subgroups, Hsp60 and MOMP responses in the TFI population did not increase significantly over the level of AI group responses. Thus, among women with similar exposure to chlamydiae, the serologic response to Hsp10 exhibited a stronger correlation with TFI than did the response to Hsp60 or MOMP. These findings support the hypothesis that the serological response toC. trachomatisheat shock proteins is associated with the severity of disease and identifies Hsp10 as an antigen recognized by a significant proportion of women with TFI.
Clearance and Organ Distribution ofMycobacterium tuberculosisLipoarabinomannan (LAM) in the Presence and Absence of LAM-Binding Immunoglobulin M
Authors: Glatman-Freedman Aharona , Mednick Aron J. , Lendvai Nikoletta , Casadevall Arturo
Published: May 2009

Lipoarabinomannan (LAM) is a component of the mycobacterial surface which has been associated with a variety of deleterious effects on immune system function. Despite the importance of LAM to the pathogenesis of mycobacterial infection, there is no information available on its fate in vivo. In this study, we determined the pharmacokinetics and tissue distribution of exogenously administered LAM in mice. For measurements of serum and tissue LAM concentrations, we developed an enzyme-linked immunosorbent assay which used monoclonal antibodies of different isotypes to capture and detect LAM at concentrations of ≥0.4 μg/ml. Intravenous administration of LAM to mice resulted in transient serum levels with organ deposition in the spleen and in the liver. Immunohistochemical studies localized LAM to the spleen marginal zone macrophages and, to a lesser degree, to liver macrophages. When LAM was administered to mice previously given a LAM-binding immunoglobulin M (IgM), LAM was very rapidly cleared from circulation. In those mice, deposition of LAM in the spleen was significantly reduced while LAM deposition in the liver increased. Administration of LAM-binding IgM resulted in significant levels of IgM to LAM in bile consistent with an increased hepatobiliary excretion of LAM in the presence of specific antibody. Bile, liver extracts, and bile salts were found to rapidly inactivate the immunoreactivity of LAM. The results indicate that serum clearance and organ deposition of LAM in mice are affected by the presence of LAM-binding antibody and suggest a mechanism by which antibody could modify the course of mycobacterial infection.
Isolates ofChlamydia trachomatisThat Occupy Nonfusogenic Inclusions Lack IncA, a Protein Localized to the Inclusion Membrane
Authors: Suchland Robert J. , Rockey Daniel D. , Bannantine John P. , Stamm Walter E.
Published: May 2009

The chlamydiae are obligate intracellular pathogens that occupy a nonacidified vacuole, termed an inclusion, throughout their developmenal cycle. When an epithelial cell is infected with multipleChlamydia trachomatiselementary bodies, they are internalized by endocytosis into individual phagosomal vacuoles that eventually fuse to form a single inclusion. In the course of large-scale serotyping studies in which fluorescent antibody staining of infected cells was used, a minority of strains that had an alternate inclusion morphology were identified. These variants formed multiple nonfusogenic inclusions in infected cells, with the number of independent inclusions per cell varying directly with the multiplicity of infection. Overall the nonfusogenic phenotype was found in 1.5% (176 of 11,440) of independent isolates. Nonfusing variants were seen inC. trachomatisserovars B, D, D−, E, F, G, H, Ia, J, and K. The nonfusing phenotype persisted through repeated serial passage, and the phenotype was consistent in four mammalian host cell lines. Fluorescence microscopy and immunoblotting with antisera directed at proteins in theC. trachomatisinclusion membrane revealed that one such protein, IncA, was not detected in the inclusion membrane in each tested nonfusogenic strain. The distributions of other chlamydial proteins, including one additional Inc protein, were similar in wild-type and variant strains. TheincAcoding and upstream regions were amplified and sequenced from the prototype serovar D and two nonfusing serovar D(s)strains. Three nucleotide changes were discovered in the D(s)incAgene, leading to two amino acid changes within the predicted D(s)IncA sequence. These studies demonstrate a subgroup of variantC. trachomatisisolates that form nonfusing inclusions; the variant phenotype is associated with the absence of detectable IncA and with an alteredincAsequence that modifies the characteristic hydrophobic domain of the IncA protein.
Characterization of a Macrophage-Specific Infectivity Locus (
milA
) of
Legionella pneumophila
Authors: Harb Omar S. , Abu Kwaik Yousef
Published: May 2009

Legionella pneumophila
has been shown to possess multiple genetic loci that play roles in its ability to survive within host cells. The
mil
(macrophage-specific infectivity loci) mutants of
L. pneumophila
exhibit a spectrum of defects in intracellular survival in and cytopathogenicity to macrophages and alveolar epithelial cells. This study characterizes one of the
mil
mutants (GB111). Intracellular growth of GB111 in macrophages was approximately 100- to 1,000-fold less than that of AA100, the parental strain, at 24 and 48 h postinfection. This defect in turn corresponded to a defect in cytopathogenicity. Sequence analysis of the affected GB111 open reading frame (ORF) revealed it to encode a putative transport protein, and the ORF was designated
milA
. The phenotypic defect of the
milA
mutant was complemented with a PCR fragment containing only
milA
, indicating that the defect in GB111 was due to the disruption of
milA
. Intracellular trafficking of the mutant was examined by laser scanning confocal microscopy. The data showed that 50% of the GB111 phagosomes colocalized with the late endosomal/lysosomal marker LAMP-2 (2 and 4 h postinfection), while less than 10% of the AA100 phagosomes colocalized with this marker. On the other hand, over 80% of the GB111 phagosomes were similar to the AA100 phagosome in that they were devoid of LAMP-1 and cathepsin D, and they were colocalized with the endoplasmic reticulum (ER) marker BiP. However, the number of GB111 phagosomes that colocalized with BiP decreased to 50% 6 h postinfection compared to that of AA100, which remained constant (80% colocalization). Thus, compared to AA100, the
milA
mutation caused a defect in intracellular replication, which was associated with colocalization of the phagosome with LAMP-2 and BiP, while colocalization with LAMP-1 and cathepsin D was not affected.
Innate Immunity to Amebic Liver Abscess Is Dependent on Gamma Interferon and Nitric Oxide in a Murine Model of Disease
Authors: Seydel Karl B. , Smith Sara J. , Stanley Samuel L.
Published: May 2009

Evidence from in vitro studies suggests that gamma interferon (IFN-γ) and nitric oxide (NO) are important in host defense against the protozoan parasite
Entamoeba histolytica
. We used SCID mice with targeted disruption of the IFN-γ receptor gene and mice with targeted disruption of the gene encoding inducible NO synthase to show that IFN-γ plays a role in the innate immunity to amebic liver abscess seen in SCID mice while NO is required for control of amebic liver abscess in immunocompetent mice.
ExoT of Cytotoxic
Pseudomonas aeruginosa
Prevents Uptake by Corneal Epithelial Cells
Authors: Cowell Brigitte A. , Chen David Y. , Frank Dara W. , Vallis Amy J. , Fleiszig Suzanne M. J.
Published: May 2009

The presence of invasion-inhibitory activity that is regulated by the transcriptional activator ExsA of cytotoxic
Pseudomonas aeruginosa
has previously been proposed. The results of this study show that both ExoT and ExoS, known type III secreted effector proteins of
P. aeruginosa
that are regulated by ExsA, possess this activity. Invasion was reduced 94.4% by ExoT and 96.0% by ExoS. Invasion-inhibitory activity is not linked to ADP-ribosylation activity, at least for ExoS, since a noncatalytic mutant also inhibits uptake by an epithelial cell line (invasion was reduced 96.0% by ExoSE381A).
Resistance of Transgenic Mice Expressing Human Group II Phospholipase A2 toEscherichia coliInfection
Authors: Laine V. Jukka O. , Grass David S. , Nevalainen Timo J.
Published: May 2009

Group II phospholipase A2 (PLA2) is a newly recognized antibacterial acute-phase protein. Recently we observed that transgenic mice expressing group II PLA2 (PLA2+mice) were able to resist experimentalStaphylococcus aureusinfection by killing the bacteria, as indicated by improved survival and by the small numbers of live bacteria in their tissues (V. J. O. Laine, D. S. Grass, and T. J. Nevalainen, J. Immunol. 162:7402–7408, 1999). To establish the role of group II PLA2 inEscherichia coliinfection, the host responses of PLA2+mice and their PLA2-deficient C57BL/6J littermates (PLA2−mice) were studied after intraperitoneal administration ofE. coli. The levels of group II PLA2 in sera of PLA2+mice increased after the administration ofE. coli, and the concentration of group II PLA2 correlated significantly with the catalytic activity of PLA2 in serum. PLA2+mice showed lower rates of mortality and less bacterial growth in peritoneal lavage fluid, blood, and spleen and liver tissues than PLA2−mice. Unlike the observations with staphylococcal infection, serum and peritoneal lavage fluid did not inhibit the growth ofE. coliin vitro. The results indicate that expression of the group IIPLA2transgene improves the host defense of mice againstE. coliinfection.
Cleavage of models for RNA mediated by a diZn(II) complex of bis[1,4-N1,N1′(1,5,9-triazacyclododecanyl)]butane in methanol and ethanol
Authors: Liu C. Tony , Melnychuk Stephanie A. , Liu Chaomin , Neverov Alexei A. , Brown R. Stan
Published: May 2009

The cleavage of seven RNA model 2-hydroxypropyl aryl phosphates (1) catalyzed by a dinuclear Zn(II) complex of bis[1,4-N1,N1′(1,5,9-triazacyclododecanyl)]butane (4) was studied in methanol and ethanol at 25 °C under pH controlled conditions. The results are compared with what was reported earlier for the dinuclear Zn(II) complex of the lower homologue bis[1,3-N1,N1′(1,5,9-triazacyclododecanyl)]propane (3). In methanol, the higher homologue exhibits saturation binding with substrates having poor aryloxy leaving groups. With good leaving groups there is an observed linear dependence of kobs versus complex concentration without saturation binding over the catalyst concentration range investigated. In ethanol, strong saturation binding between the active form of the catalyst ((RO–):Zn(II)2:4) and all substrates is observed, the results observed in both solvents being similar to what was reported for the lower (RO–):Zn(II)2:3 homologue. Energetics calculations are presented for the (RO–):Zn(II)2:4-catalyzed cleavage of each substrate in both solvents to assess the catalytic efficiency via the ΔΔG‡ for catalyst binding a transition state comprising [RO–:1]‡ or its kinetic equivalent.
Chiral α-substituted allylboronates in a one-pot three-component asymmetric allylic alkylation/carbonyl allylation reaction sequence — Applications to the syntheses of (+)-(3R,5R)-3-hydroxy-5-decanolide and (–)-massoialactone
Authors: Carosi Lisa , Hall Dennis G.
Published: May 2009

The use of different organomagnesium reagents in the copper-catalyzed allylic alkylation of 3-chloropropenyl boronates with chiral phosphoramidite ligands produces the desired α-substituted allylic boronate reagents in high regioselectivity and with modest to high enantioselectivities (up to 96% ee). The size of the incoming alkyl substituent from the organomagnesium reagent was found to impact the yield and selectivity of the allylic alkylation. A one-pot procedure for the preparation of these chiral allylic boronates followed by a Lewis acid (BF3) catalyzed addition to aldehydes delivers the desired allylboration products, homoallylic secondary alcohols, in good yields and very high diastereoselectivity. This three-component reaction methodology was applied to the syntheses of two lactone-containing natural products, (–)-massoialactone and (+)-(3R,5R)-3-hydroxy-5-decanolide. The key step of these syntheses involved the one-pot enantioselective copper-catalyzed allylic alkylation/allylboration reaction with a benzylic aldehyde, and afforded the desired product in 87% yield, 92% ee, and high E/Z selectivity in a ratio of 22:1. Remarkably, the allylic alkylation step of this sequential reaction was performed with a low catalyst loading of 2 mol% on a scale of >15 mmol that can provide multiple grams of the three-component product.
Exhaled nitric oxide estimation by a simple and efficient noninvasive technique and its utility as a marker of airway inflammation in mice
Authors: Ahmad Tanveer , Mabalirajan Ulaganathan , Joseph Duraisamy Arul , Makhija Lokesh , Singh Vijay Pal , Ghosh Balaram , Agrawal Anurag
Published: May 2009

Allergic airway inflammation (AI) is commonly associated with enhanced exhaled nitric oxide (ENO) in both humans and mice. Since mouse models are being used to understand various mechanisms of asthma, a noninvasive, simple, and reproducible method to determine ENO in mice is required for serial nonterminal assessment that can be used independent of environmental situations in which the ambient air contains substantial amounts of NO as a contaminant. The aim of this study was to noninvasively measure ENO in individual mice and to test its utility as a marker of AI in different models of allergic AI. We modified the existing ENO measuring methods by incorporating flushing and washout steps that allowed simple but reliable measurements under highly variable ambient NO conditions (1–100 ppb). This method was used to serially follow ENO in acute and chronic models of allergic AI in mice. ENO was reproducibly measured by this modified method and was positively correlated to AI in both acute and chronic models of asthma but was not independently related to airway remodeling. Resolution of AI and other related parameters in dexamethasone-treated mice resulted in reduction of ENO, further confirming this association. Restriction of allergen challenge to pulmonary but not nasal airways was associated with a smaller increase in ENO compared with allergen challenge to both. Hence, ENO can now be reliably measured in mice independent of ambient NO levels and is a valid biomarker for AI. However, nasal and pulmonary airways are likely to be independent sources of ENO, and any results must be interpreted as such.
Aging and muscle fiber type alter K+ channel contributions to the myogenic response in skeletal muscle arterioles
Authors: Kang Lori S. , Kim SeJeong , Dominguez James M. , Sindler Amy L. , Dick Gregory M. , Muller-Delp Judy M.
Published: May 2009

Aging diminishes myogenic tone in arterioles from skeletal muscle. Recent evidence indicates that both large-conductance Ca2+-activated (BKCa) and voltage-dependent (KV) K+ channels mediate negative feedback control of the myogenic response. Thus we tested the hypothesis that aging increases the contributions of KV and BKCa channels to myogenic regulation of vascular tone. Because myogenic responsiveness differs between oxidative and glycolytic muscles, we predicted that KV and BKCa channel contributions to myogenic responsiveness vary with fiber type. Myogenic responses of first-order arterioles from the gastrocnemius and soleus muscles of 4- and 24-mo-old Fischer 344 rats were evaluated in the presence and absence of 4-aminopyridine (5 mM) or iberiotoxin (30 nM), inhibitors of KV and BKCa, respectively. 4-Aminopyridine enhanced myogenic tone with aging and normalized age-related differences in both muscle types. By contrast, iberiotoxin eliminated age-related differences in soleus arterioles and had no effect in gastrocnemius vessels. KV1.5 is an integral component of KV channels in vascular smooth muscle; therefore, we determined the relative protein expression of KV1.5, as well as BKCa, in soleus and gastrocnemius arterioles. Immunoblot analysis revealed no differences in KV1.5 protein with aging or between variant fiber types, whereas BKCa protein levels declined with age in arterioles from both muscle groups. Collectively, these results suggest that the contribution of BKCa to myogenic regulation of vascular tone changes with age in soleus muscle arterioles, whereas increased KV channel expression and negative feedback regulation of myogenic tone increases with advancing age in arterioles from both oxidative and glycolytic muscles.