bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Frequency Expression for the In-Plane Vibrations of Rotating Rings
Authors: Koff B. L. , El-Aini Y. M.
Published: April 2008

An approximate but accurate expression for determining the reference in-plane flexural frequencies of rotating rings is presented. The ring reference frequencies are with respect to a coordinate system that rotates with the ring at the mean speed of the forward and backward traveling waves analogous to the standing wave approach for rotating disks. The formula is based on adapting the correction factor for shear, centrifugal stiffening, and centrifugal mass of prismatic bars to be applied to Hoppe’s “Classical” formula for stationary, slender, inextensible rings. The result is a closed-form analytical solution applicable to arbitrary shaped rotating rings with distributed loading. The formula has been verified for a wide range of ring radial depths and nodal diameters by comparison to elaborate NASTRAN solid finite element models that account for shear, centrifugal stiffening, and centrifugal mass effects. Excellent correlations, within 1 percent, for all test cases were achieved. Forward and backward traveling-wave frequencies are obtained by using the reference frequency expression into Bryan’s “classical” formula for thin rotating rings. Centrifugal mass contribution was shown to be particularly important for thin rings vibrating at low nodal diameters.
Multi-objective Optimization of Rotor-Bearing System With Critical Speed Constraints
Authors: Shiau T. N. , Chang J. R.
Published: April 2008

An efficient optimal design algorithm is developed to minimize, individually or simultaneously, the total weight of the shaft and the transmitted forces at the bearings. These factors play very important roles in designing a rotor-bearing system under the constraints of critical speeds. The cross-sectional area of the shaft, the bearing stiffness, and the positions of bearings and disks are chosen as the design variables. The dynamic characteristics are determined by applying the generalized polynomial expansion method and the sensitivity analysis is also investigated. For multi-objective optimization, the weighting method (WM), the goal programming method (GPM), and the fuzzy method (FM) are applied. The results show that the present multi-objective optimization algorithm can greatly reduce both the weight of the shaft and the forces at the bearings with critical speed constraints.
Optimum Design of Rotor-Bearing Systems With Eigenvalue Constraints
Authors: Chen T.-Y. , Wang B. P.
Published: April 2008

The analysis and design of rotor-bearing systems with gyroscopic effects are discussed in this paper. The original problem of this nonproportionally damped mechanism is transformed into the state space form so that the transformed problem is similar to the eigenvalue problem for an undamped system. It can be easily solved by widely available eigensolvers and the eigenvalue sensitivities needed for the design optimization can also be obtained conveniently using the transformed form. The sequential linear programming technique is employed to solve the design optimization problem. The easy implementation of this proposed approach with a general purpose finite element program is shown in the solution algorithm.
A Study of the Influence of Bearing Clearance on Lateral Coupled Shaft/Disk Rotordynamics
Authors: Flowers G. T. , Wu Fang Sheng
Published: April 2008

This study examines the influence of bearing clearance on the dynamic behavior of a rotating, flexible disk/shaft system. Most previous work in nonlinear rotordynamics has tended to concentrate separately on shaft vibration or on bladed disk vibration, neglecting the coupling dynamics between them. The current work examines the important rotordynamic behavior of coupled disk/shaft dynamics. A simplified nonlinear model is developed for lateral vibration of a rotor system with a bearing clearance nonlinearity. The steady-state dynamic behavior of this system is explored using numerical simulation and limit cycle analysis. It is demonstrated that bearing clearance effects can produce superharmonic vibration that may serve to excite high-amplitude disk vibration. Such vibration could lead to significantly increased bearing loads and catastrophic failure of blades and disks. In addition, multivalued responses and aperiodic behavior were observed.
Investigation of the Vibration of a Blade With Friction Damper by HBM
Authors: Wang J. H. , Chen W. K.
Published: April 2008

The friction damper has been widely used to reduce the resonant vibration of blades. The most commonly used methods for studying the dynamic behavior of a blade with a friction damper are direct integration methods. Although the harmonic balance method (HBM) is a well-known method for studying nonlinear vibration problems, generally only a one-term approximation has been proposed to study the nonlinear vibration of a frictionally damped blade. In this work, a HMB procedure with a multiterm approximation is proposed. The results show that the steady-state response and other related behavior of a frictionally damped blade can be predicted accurately and quickly by an HBM with a multiterm approximation.
Coupled Multidisciplinary Simulation of Composite Engine Structures in Propulsion Environment
Authors: Chamis C. C. , Singhal S. N.
Published: April 2008

A computational simulation procedure is described for the coupled response of multilayered multimaterial composite engine structural components that are subjected to simultaneous multidisciplinary thermal, structural, vibration, and acoustic loading including the effect of hostile environments. The simulation is based on a three-dimensional finite element analysis technique in conjunction with structural mechanics codes and with the acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i.e., the laminate/ply/fiber and matrix constituents, via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometric, material, loading, and environmental behavior of aircraft engine fan blades are presented. Results for deformed shape, vibration frequencies, mode shapes, and acoustic noise emitted from the fan blade are discussed for their coupled effect in hot and humid environments. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multidisciplinary computational simulation and the various advantages of composite materials compared to metals.
Experimental and Analytical Investigation of Hybrid Squeeze Film Dampers
Authors: El-Shafei A.
Published: April 2008

A new concept for actively controlling high-speed rotating machinery is investigated both analyically and experimentally. The controlling mechanism consists of a hybrid squeeze film damper (patent pending) that can be adaptively controlled to change its characteristics according to the instructions of a controller. In an extreme case the hybrid damper can act as a long damper, which is shown to be effective in reducing the amplitude of vibration of rotating machinery. In the other extreme the hybrid damper acts as a short damper, which is shown to be effective in reducing the force transmitted to the support. In the long damper configuration the oil flow is circumferential, while in the short damper configuration the oil flow is predominantly axial. The hybrid damper is designed to operate in either the short or the long damper configuration by controlling the positions of two movable sealing rings. The hybrid damper was tested on a Bently Nevada Rotor Kit and it is shown experimentally that the long damper configuration is extremely efficient at controlling the amplitude of vibration and the short damper configuration reduces the force transmitted to the support.
A Chambered Porous Damper for Rotor Vibration Control: Part I—Concept Development
Authors: Tecza J. , Walton J.
Published: April 2008

In this paper a novel, high-load chambered porous damper design, supporting analysis, and experimental results are presented. It was demonstrated that significant damping can be generated from the viscous discharge losses of capillary tubes arranged in chambered segments with large radial clearances and that the resulting damping is predictable and fairly constant with speed and eccentricity ratio. This design avoids the nonlinearities associated with high-eccentricity operation of conventional squeeze film dampers. Controlled orbit tests with a porous chambered configuration were completed and favorably compared with theoretical predictions. The ability to accommodate high steady-state and transient imbalance conditions makes this damper well suited to a wide range of rotating machinery, including aircraft gas turbine engines.
Factors Influencing the Circumferential Liquid Distribution From Pressure-Swirl Atomizers
Authors: Chen S. K. , Lefebvre A. H. , Rollbuhler J.
Published: April 2008

Measurements of circumferential liquid distribution are carried out over ranges of injection pressure from 0.34 to 1.72 MPa (50 to 250 psi) using five different simplex nozzles to achieve variations in the discharge orifice length/diameter ratio from 0.5 to 4.0. Two additional simplex nozzles of the same flow number are also examined in order to ascertain the effect of variations in the number of swirl chamber feed slots on circumferential liquid distribution. Mixtures of water and glycerine are used to provide a twelve to one variation in liquid viscosity. The results obtained show that spray uniformity improves markedly at higher injection pressures. Increase in liquid viscosity also has a beneficial effect on spray uniformity. The most uniform circumferential liquid distributions are obtained with nozzles having a discharge orifice length/diameter ratio of between 1 1/2 and 2.
Studies of Jet Fuel Thermal Stability in a Flowing System
Authors: Heneghan S. P. , Martel C. R. , Williams T. F. , Ballal D. R.
Published: April 2008

A flowing, single-pass heat exchanger test rig, with a fuel capacity of 189 liters, has been developed to evaluate jet fuel thermal stability. This “Phoenix Rig” is capable of supplying jet fuel to a 2.15 mm i.d. tube at a pressure up to 3.45 MPa, fuel temperature up to 900 K, and a fuel-tube Reynolds number in the range 300–11,000. Using this test rig, fuel thermal stability (carbon deposition rate), dissolved oxygen consumption, and methane production were measured for three baseline jet fuels and three fuels blended with additives. Such measurement were performed under oxygen-saturation or oxygen-starved conditions. Tests with all of the blended fuel samples showed a noticeable improvement in fuel thermal stability. Both block temperature and test duration increased the total carbon deposits in a nonlinear fashion. Interestingly, those fuels that need a higher threshold temperature to force the consumption of oxygen exhibited greater carbon deposits than those that consume oxygen at a lower temperature. These observations suggested a complicated relationship between the formation of carbon deposits and the temperature-driven consumption of oxygen. A simple analysis, based on a bimolecular reaction rate, correctly accounted for the shape of the oxygen consumption curve for various fuels. This analysis yielded estimates of global bulk parameters of oxygen consumption. The test rig yielded quantitative results, which will be very useful in evaluating fuels additives, understanding the chemistry of deposit formation, and eventually developing a global chemistry model.
Semianalytical Correlations for NOx, CO, and UHC Emissions
Authors: Rizk N. K. , Mongia H. C.
Published: April 2008

To meet the future goals of reduced emissions produced by gas turbine combustors, a better understanding of the process of formation of various pollutants is required. Both empirical and analytical approaches are used to provide the exhaust concentrations of pollutants of interest such as NOx, CO, and unburned hydrocarbon with varying degrees of success. In the present investigation, an emission model that simulates the combustor by a number of reactors representing various combustion zones is proposed. A detailed chemical kinetic scheme was used to provide a fundamental basis for the derivation of a number of expressions that simulate the reaction scheme. The model addresses the combined effects of spray evaporation and mixing in the reaction zone. The model validation included the utilization of a large data base obtained for an annular combustor of a modern turbopropulsion engine. In addition to the satisfactory agreement with the measurements, the model provided insight into the regions within the combustor that could be responsible for the excessive formation of emissions. Methods to reduce the emissions may be implemented in light of such information.
Deposition of Volcanic Materials in the Hot Sections of Two Gas Turbine Engines
Authors: Kim J. , Dunn M. G. , Baran A. J. , Wade D. P. , Tremba E. L.
Published: April 2008

This paper reports the results of a series of tests designed to determine the melting and subsequent deposition behavior of volcanic ash cloud materials in modern gas turbine engine combustors and high-pressure turbine vanes. The specific materials tested were Mt. St. Helens ash and a soil blend containing volcanic ash (black scoria) from Twin Mountain, NM. Hot section test systems were built using actual engine combustors, fuel nozzles, ignitors, and high-pressure turbine vanes from an Allison T56 engine can-type combustor and a more modern Pratt and Whitney F-100 engine annular-type combustor. A rather large turbine inlet temperature range can be achieved using these two combustors. The deposition behavior of volcanic materials as well as some of the parameters that govern whether or not these volcanic ash materials melt and are subsequently deposited are discussed.
Progress in Vapor Phase Lubrication Technology
Authors: Placek D. G. , Freiheit T.
Published: April 2008

Improving the efficiency of engine performance will require the design of systems with higher operating temperatures and pressures. These conditions will stress traditional lubricants beyond their current performance capabilities, and require the development of improved methods for friction and wear reduction. The most revolutionary approach to high-temperature lubrication is the concept of vapor phase delivery. An ashless organic compound can be vaporized by the heat of the operating engine or a carrier gas, and introduced into the ring zone of the cylinder. The vapor condenses or chemically binds with the piston ring or cylinder wall, and provides boundary lubrication. A minute amount of lubricant is constantly introduced in order to maintain a lubricating film. Each stroke of the piston shears off a portion of the lubricant layer, but condensing vapor continually replaces the surface film. Lubricant contributions to exhaust emissions are expected to be lower than those currently resulting from liquid lubricants. Vapor phase lubrication is an emerging concept that may be the key to the development of a commercial low heat rejection engine with improved energy efficiency and reduced emissions. The Department of Energy continues to fund research at a variety of industrial and academic institutions. Basic concepts and recent developments in the field of vapor phase lubrication will be reviewed.
Carbonyl Compounds and PAH Emissions From CNG Heavy-Duty Engine
Authors: Gambino M. , Cericola R. , Corbo P. , Iannaccone S.
Published: April 2008

Previous works carried out in Istituto Motori laboratories have shown that natural gas is a suitable fuel for general means of transportation. This is because of its favorable effects on engine performance and pollutant emissions. The natural gas fueled engine provided the same performance as the diesel engine, met R49 emission standards, and showed very low smoke levels. On the other hand, it is well known that internal combustion engines emit some components that are harmful for human health, such as carbonyl compounds and polycyclic aromatic hydrocarbons (PAH). This paper shows the results of carbonyl compounds and PAH emissions analysis for a heavy-duty Otto cycle engine fueled with natural gas. The engine was tested using the R49 cycle that is used to measure the regulated emissions. The test analysis has been compared with an analysis of a diesel engine, tested under the same conditions. Total PAH emissions from the CNG engine were about three orders of magnitude lower than from the diesel engine. Formaldehyde emission from the CNG engine was about ten times as much as from the diesel engine, while emissions of other carbonyl compounds were comparable.
Cultivating a New Nation
Authors: Kingsland Sharon
Published: April 2008

Fruits and Plains
. The Horticultural Transformation of America.
By Philip J. Pauly
. Harvard University Press, Cambridge, MA, 2008. 350 pp. $39.95, £25.95, €30. ISBN 9780674026636.

Examining the long history of the engineering of plants in the United States, the author discusses how horticulturalists shaped the landscapes and influenced the activities and experiences of the inhabitants.
Presence of Plasmid-Mediated Quinolone Resistance in
Klebsiella pneumoniae
Isolates Possessing
bla
KPC
in the United States
Authors: Endimiani Andrea , Carias Lenore L. , Hujer Andrea M. , Bethel Christopher R. , Hujer Kristine M. , Perez Federico , Hutton Rebecca A. , Fox William R. , Hall Geraldine S. , Jacobs Michael R. , Paterson David L. , Rice Louis B. , Jenkins Stephen G. , Tenover Fred C. , Bonomo Robert A.
Published: April 2008

The presence of plasmid-mediated quinolone resistance genes [i.e.,
qnrA
,
qnrB
,
qnrS
,
aac(6
′
)-Ib-cr
, and
qepA
] was evaluated among 42
bla
KPC
-containing
Klebsiella pneumoniae
isolates collected in the eastern United States. One isolate carried the
bla
KPC-3
and
qnrB19
genes on the same conjugative plasmid, whereas another carried the
bla
KPC-3
and
qnrA1
genes on separate plasmids.
Telavancin Penetration into Human Epithelial Lining Fluid Determined by Population Pharmacokinetic Modeling and Monte Carlo Simulation
Authors: Lodise Thomas P. , Gotfried Mark , Barriere Steven , Drusano George L.
Published: April 2008

Telavancin is an investigational bactericidal lipoglycopeptide with a multifunctional mechanism of action, as demonstrated against methicillin-resistant
Staphylococcus aureus
. While the plasma pharmacokinetics have been described, the extent of the penetration of the drug into the lung, measured by the epithelial lining fluid (ELF), remains unknown. Population modeling and Monte Carlo simulation were employed to estimate the penetration of telavancin into ELF. Plasma and ELF pharmacokinetic data were obtained from 20 healthy volunteers, and the pharmacokinetic samples were assayed by a validated liquid chromatography-tandem mass spectrometry technique. Concentration-time profiles in plasma and ELF were simultaneously modeled using a three-compartment model with zero-order infusion and first-order elimination and transfer. The model parameters were identified in a population pharmacokinetic analysis (BigNPAG). Monte Carlo simulation of 9,999 subjects was performed to calculate the ELF/plasma penetration ratios by estimating the area under the concentration-time curve (AUC) for the drug in ELF (AUC
ELF
) and for the free drug in plasma (free AUC
plasma
) from zero to infinity after a single dose. After the Bayesian step, the overall fits of the model to the data were good, and plots of predicted versus observed concentrations in plasma and ELF showed slopes and intercepts very close to the ideal values of 1.0 and 0.0, respectively. The median AUC
ELF
/free AUC
plasma
penetration ratio was 0.73, and the 25th and 75th percentile value ratios were 0.43 and 1.24, respectively. In uninfected lung tissue, the median AUC
ELF
is approximately 75% of the free AUC
plasma
.
In Vitro Antibacterial Activity of CE-156811, a Novel Analog Derived from Hygromycin A
Authors: Stone Gregory G. , Girard Dennis , Finegan Steve , Duignan Joan , Schafer John , Maloney Meghan , Zaniewski Richard P. , Brickner Steven J. , Wade Sarah K. , Le Phuong T. , Huband Michael D.
Published: April 2008

We evaluated a novel truncated hygromycin A analog in which the furanose ring was replaced with a 2-fluoro-2-cyclopropylethyl substituent for its activity against multidrug resistant gram-positive bacteria and compared its activity to the activities of linezolid, quinupristin-dalfopristin, and vancomycin. CE-156811 demonstrated robust in vitro activity against gram-positive bacteria that was comparable to that of linezolid.
Francisella tularensisInvasion of Lung Epithelial Cells
Authors: Craven Robin R. , Hall Joshua D. , Fuller James R. , Taft-Benz Sharon , Kawula Thomas H.
Published: April 2008

Francisella tularensis, a gram-negative facultative intracellular bacterial pathogen, causes disseminating infections in humans and other mammalian hosts. Macrophages and other monocytes have long been considered the primary site ofF. tularensisreplication in infected animals. However, recently it was reported thatF. tularensisalso invades and replicates within alveolar epithelial cells following inhalation in a mouse model of tularemia. TC-1 cells, a mouse lung epithelial cell line, were used to study the process ofF. tularensisinvasion and intracellular trafficking within nonphagocytic cells. Live and paraformaldehyde-fixedF. tularensislive vaccine strain organisms associated with, and were internalized by, TC-1 cells at similar frequencies and with indistinguishable differences in kinetics. Inhibitors of microfilament and microtubule activity resulted in significantly decreasedF. tularensisinvasion, as did inhibitors of phosphatidylinositol 3-kinase and tyrosine kinase activity. Collectively, these results suggest thatF. tularensisepithelial cell invasion is mediated by a preformed ligand on the bacterial surface and driven entirely by host cell processes. Once internalized,F. tularensis-containing endosomes associated with early endosome antigen 1 (EEA1) followed by lysosome-associated membrane protein 1 (LAMP-1), with peak coassociation frequencies occurring at 30 and 120 min postinoculation, respectively. By 2 h postinoculation, 70.0% (± 5.5%) of intracellular bacteria were accessible to antibody delivered to the cytoplasm, indicating vacuolar breakdown and escape into the cytoplasm.
The Cytosolic Pattern Recognition Receptor NOD1 Induces Inflammatory Interleukin-8 duringChlamydia trachomatisInfection
Authors: Buchholz Kerry R. , Stephens Richard S.
Published: April 2008

Inflammation is a hallmark of chlamydial infections, but how inflammatory cytokines are induced is not well understood. Pattern recognition receptors (PRR) of the host innate immune system recognize pathogen molecules and activate intracellular signaling pathways that modulate immune responses. The role of PRR such as Toll-like receptors (TLR) and nucleotide-binding oligomerization domain (NOD) proteins in the endogenous interleukin-8 (IL-8) response induced duringChlamydia trachomatisinfection is not known. We hypothesized that a PRR is essential for the IL-8 response induced byC. trachomatisinfection. RNA interference was used to knock down the TLR signaling partner MyD88 as well as NOD1 and its signaling molecule receptor-interacting protein 2 (RIP2). IL-8 induced at 30 h postinfection byC. trachomatiswas dependent on NOD1 signaling through RIP2; however, the IL-8 response was independent of MyD88-dependent TLR signaling. Activation of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase cellular signaling pathway, which is essential for up-regulation of IL-8 in response toC. trachomatisinfection, was independent of NOD1 or RIP2. We conclude that the endogenous IL-8 response induced byC. trachomatisinfection is dependent upon NOD1 PRR signaling through RIP2 as part of a signal system requiring multiple inputs for optimal IL-8 induction. Since ERK is not activated through this pathway, a concomitant interaction between the host and bacteria is additionally required for full activation of the endogenous IL-8 response.
Novel Role of Sphingolipid Synthesis Genes in Regulating Giardial Encystation
Authors: Hernandez Yunuen , Shpak Max , Duarte Trevor T. , Mendez Tavis L. , Maldonado Rosa A. , Roychowdhury Sukla , Rodrigues Marcio L. , Das Siddhartha
Published: April 2008

Although encystation (cyst formation) is important for the survival ofGiardia lambliaoutside its human host, the molecular events that prompt encystation have not been fully elucidated. Here, we demonstrate that sphingolipids (SLs), which are important for the growth and differentiation of many eukaryotes, play key roles in giardial encystation. Transcriptional analyses showed that only three genes in the SL biosynthesis pathways are expressed and transcribed differentially in nonencysting and encystingGiardiatrophozoites. While the putative homologues of giardial serine palmitoyltransferase (gSPT) subunit genes (gspt-1and -2) are differentially expressed in nonencysting and encysting trophozoites, the giardial ceramide glucosyltransferase 1 gene (gglct-1) is transcribed only in encysting cells.l-Cycloserine, an inhibitor of gSPT, inhibited the endocytosis and endoplasmic reticulum/perinuclear targeting of bodipy-ceramide in trophozoites, and this could be reversed by 3-ketosphinganine. On the other hand,d-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP), an inhibitor of glucosylceramide synthesis, blocked karyokinesis and reduced cyst production in culture. PPMP also altered the expression of cyst wall protein transcripts in encysting cells. Phylogenetic analyses revealed that thegsptgenes are paralogs derived from an ancestralsptsequence that underwent gene duplication early in eukaryotic history. This ancestral sequence, in turn, was probably derived from prokaryotic aminoacyl transferases. In contrast,gglct-1is found in both prokaryotes and eukaryotes without any evidence of gene duplication. These studies indicate that SL synthesis genes are involved in key events in giardial biology and could serve as potential targets for developing new therapies against giardiasis.
Pilot-Scale Production and Characterization of Paramyosin, a Vaccine Candidate for Schistosomiasis Japonica
Authors: Jiz Mario , Wu Hai-Wei , Meng Rui , Pond-Tor Sunthorn , Reynolds Mindy , Friedman Jennifer F. , Olveda Remigio , Acosta Luz , Kurtis Jonathan D.
Published: April 2008

Despite effective chemotherapy, schistosomiasis remains a major public health problem in the developing world, with at least 200 million active infections resulting in significant morbidity. Rapid reinfection after treatment, accompanied by extensive residual morbidity, mandates alternative control strategies, including vaccine development. Paramyosin, a myofibrillar protein found only in invertebrates, has been widely studied as a vaccine candidate for bothSchistosoma mansoniandSchistosoma japonicum. Recently, we demonstrated that Th2-biased immune responses to paramyosin are associated with resistance to reinfection withS. japonicumin humans; however, challenges in the pilot-scale production of schistosome paramyosin have hampered further studies of this promising vaccine candidate. Here we report a method for the pilot-scale expression and purification of recombinantS. japonicumparamyosin (rSj97). rSj97 was extracted fromEscherichia coliinclusion bodies and purified with sequential anion-exchange, hydroxyapatite, and size exclusion chromatography. The purified rSj97 was >95% pure as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis and was free of significant endotoxin contamination. We demonstrate that, like native paramyosin, rSj97 adopts an alpha-helical coiled-coil tertiary structure and binds immunoglobulin and collagen. Naïve mice infected withS. japonicumproduce anti-rSj97 immunoglobulin G (IgG) antibodies as early as 4 weeks postinfection, while sera collected fromS. japonicum-infected individuals contain anti-rSj97 IgE antibodies. Our method for pilot-scale production of recombinant full-length paramyosin will facilitate preclinical evaluation of paramyosin as a vaccine for schistosomiasis.
Toll-Like Receptor 9 Regulates the Lung Macrophage Phenotype and Host Immunity in Murine Pneumonia Caused byLegionella pneumophila
Authors: Bhan Urvashi , Trujillo Glenda , Lyn-Kew Kenneth , Newstead Michael W. , Zeng Xianying , Hogaboam Cory M. , Krieg Arthur M. , Standiford Theodore J.
Published: April 2008

Experiments were performed to determine the contribution of TLR9 to the generation of protective immunity against the intracellular respiratory bacterial pathogenLegionella pneumophila. In initial studies, we found that the intratracheal (i.t.) administration ofL. pneumophilato mice deficient in TLR9 (TLR9−/−) resulted in significantly increased mortality, which was associated with an approximately 10-fold increase in the number of lung CFU compared to that of wild-type BALB/c mice. Intrapulmonary bacterial challenge in TLR9−/−mice resulted in the reduced accumulation of myeloid dendritic cells (DC) and activated CD4+T cells. Lung macrophages isolated fromLegionella-infected TLR9−/−mice displayed the impaired internalization of bacteria and evidence of alternative rather than classical activation, as manifested by the markedly reduced expression of nitric oxide and type 1 cytokines, whereas the expression of Fizz-1 and arginase-1 was enhanced. The adoptive transfer of bone marrow-derived DC from syngeneic wild-type, but not TLR9−/−, mice administered i.t. reconstituted anti-legionella immunity and restored the macrophage phenotype in TLR9−/−mice. Finally, the i.t., but not intraperitoneal, administration of the TLR9 agonist molecule CpG oligodeoxynucleotide stimulated protective immunity inLegionella-infected mice. In total, our findings indicate that TLR9 is required for effective innate immune responses against the intracellular bacterial pathogenL. pneumophila, and approaches to maximize TLR9-mediated responses may serve as a means to augment antibacterial immunity in pneumonia.
Nasal Immunization with
Porphyromonas gingivalis
Outer Membrane Protein Decreases
P. gingivalis
-Induced Atherosclerosis and Inflammation in Spontaneously Hyperlipidemic Mice
Authors: Koizumi Y. , Kurita-Ochiai T. , Oguchi S. , Yamamoto M.
Published: April 2008

Porphyromonas gingivalis
has been shown to accelerate atherosclerotic lesion development in hyperlipidemic animals. We assessed the potential of a nasal vaccine against
P. gingivalis
infection for the prevention of atherosclerosis. Apolipoprotein E-deficient spontaneously hyperlipidemic (Apoe
shl
) mice were nasally immunized with the 40-kDa outer membrane protein (OMP) of
P. gingivalis
plus cholera toxin (CT) as adjuvant and then challenged intravenously with
P. gingivalis
strain 381. The animals were euthanized 11 or 14 weeks later. Atheromatous lesions in the proximal aorta of each animal were analyzed histomorphometrically, and the serum concentrations of 40-kDa OMP-specific antibodies and cytokines were determined. The areas of the aortic sinus that were covered with atherosclerotic plaque and the serum levels of inflammatory cytokines and chemokines were increased in Apoe
shl
mice challenged with
P. gingivalis
compared to nonchallenged mice. In comparison, nasal immunization with 40-kDa OMP plus CT significantly reduced atherosclerotic plaque accumulation in the aortic sinus and lowered the serum levels of cytokines and chemokines compared to nonimmunized animals. Nasal immunization also induced 40-kDa OMP-specific serum immunoglobulin G (IgG) and saliva IgA antibody responses. These findings suggest that systemic infection with
P. gingivalis
accelerates atherosclerosis in Apoe
shl
mice, and 40-kDa OMP plus CT may be an effective nasal vaccine for the reduction of atherosclerosis accelerated by
P. gingivalis
in the hyperlipidemic mouse model.
Metal Binding Specificity of the MntABC Permease ofNeisseria gonorrhoeaeand Its Influence on Bacterial Growth and Interaction with Cervical Epithelial Cells
Authors: Lim Karen H. L. , Jones Christopher E. , vanden Hoven Rachel N. , Edwards Jennifer L. , Falsetta Megan L. , Apicella Michael A. , Jennings Michael P. , McEwan Alastair G.
Published: April 2008

mntABCfromNeisseria gonorrhoeaeencodes an ABC permease which includes a periplasmic divalent cation binding receptor protein of the cluster IX family, encoded bymntC. Analysis of anmntCmutant showed that growth ofN. gonorrhoeaecould be stimulated by addition of either manganese(II) or zinc(II) ions, suggesting that the MntABC system could transport both ions. In contrast, growth of themntABmutant in liquid culture was possible only when the medium was supplemented with an antioxidant such as mannitol, consistent with the view that ion transport via MntABC is essential for protection ofN. gonorrhoeaeagainst oxidative stress. Using recombinant MntC, we determined that MntC binds Zn2+and Mn2+with almost equal affinity (dissociation constant of ∼0.1 μM). Competition assays with the metallochromic zinc indicator 4-(2-pyridylazo)resorcinol showed that MntC binds Mn2+and Zn2+at the same binding site. Analysis of theN. gonorrhoeaegenome showed that MntC is the only Mn/Zn metal binding receptor protein cluster IX in this bacterium, in contrast to the situation in many other bacteria which have systems with dedicated Mn and Zn binding proteins as part of distinctive ABC cassette permeases. Both themntCandmntABmutants had reduced intracellular survival in a human cervical epithelial cell model and showed reduced ability to form a biofilm. These data suggest that the MntABC transporter is of importance for survival ofNeisseria gonorrhoeaein the human host.
Quality Control Assessment of Human Immunodeficiency Virus Type 2 (HIV-2) Viral Load Quantification Assays: Results from an International Collaboration on HIV-2 Infection in 2006
Authors: Damond Florence , Benard Antoine , Ruelle Jean , Alabi Abraham , Kupfer Bernd , Gomes Perpetua , Rodes Berta , Albert Jan , Böni Jürg , Garson Jeremy , Ferns Bridget , Matheron Sophie , Chene Geneviève , Brun-Vezinet Françoise
Published: April 2008

Human immunodeficiency virus type 2 (HIV-2) RNA quantification assays used in nine laboratories of the ACHI
E
V
2E
(A Collaboration on HIV-2 Infection) study group were evaluated. In a blinded experimental design, laboratories quantified three series of aliquots of an HIV-2 subtype A strain, each at a different theoretical viral load. Quantification varied between laboratories, and international standardization of quantification assays is strongly needed.
Structural Analysis of Human Immunodeficiency Virus Type 1 CRF01_AE Protease in Complex with the Substrate p1-p6
Authors: Bandaranayake Rajintha M. , Prabu-Jeyabalan Moses , Kakizawa Junko , Sugiura Wataru , Schiffer Celia A.
Published: April 2008

The effect of amino acid variability between human immunodeficiency virus type 1 (HIV-1) clades on structure and the emergence of resistance mutations in HIV-1 protease has become an area of significant interest in recent years. We determined the first crystal structure of the HIV-1 CRF01_AE protease in complex with the p1-p6 substrate to a resolution of 2.8 Å. Hydrogen bonding between the flap hinge and the protease core regions shows significant structural rearrangements in CRF01_AE protease compared to the clade B protease structure.
Selection of T1249-Resistant Human Immunodeficiency Virus Type 1 Variants
Authors: Eggink Dirk , Baldwin Christopher E. , Deng Yiqun , Langedijk Johannes P. M. , Lu Min , Sanders Rogier W. , Berkhout Ben
Published: April 2008

Human immunodeficiency virus type 1 (HIV-1) entry is an attractive target for therapeutic intervention. Two drugs that inhibit this process have been approved: the fusion inhibitor T20 (enfuvirtide [Fuzeon]) and, more recently, the CCR5 blocker maraviroc (Selzentry). T1249 is a second-generation fusion inhibitor with improved antiviral potency compared to the first-generation peptide T20. We selected T1249-resistant HIV-1 variants in vitro by serial virus passage in the presence of increasing T1249 doses after passage with wild-type and T20-resistant variants. Sequence analysis revealed the acquisition of substitutions within the HR1 region of the gp41 ectodomain. The virus acquired mutations of residue V38 to either E or R in 10 of 19 cultures. Both E and R at position 38 were confirmed to cause resistance to T1249, as well as cross-resistance to T20 and C34, but not to the third-generation fusion inhibitor T2635. We also observed substitutions at residues 79 and 90 (Q79E and K90E), which provide modest resistance to T1249 and, interestingly, T2635. Thus, the gp41 amino acid position implicated in T20 resistance (V38 replaced by A, G, or W) is also responsible for T1249 resistance (V38 replaced by E, R, or K). These results indicate that T20 and T1249 exhibit very similar inhibition modes that call for similar but not identical resistance mutations. All T1249-resistant viruses with changes at position 38 are cross resistant to T20, but not vice versa. Furthermore, substitutions at position 38 do not provide resistance to the third-generation inhibitor T2635, while substitution at positions 79 and 90 do, suggesting different resistance mechanisms.
Oligomerization of ICP4 and Rearrangement of Heat Shock Proteins May Be Important for Herpes Simplex Virus Type 1 Prereplicative Site Formation
Authors: Livingston Christine M. , DeLuca Neal A. , Wilkinson Dianna E. , Weller Sandra K.
Published: April 2008

Herpes simplex virus type 1 (HSV-1) DNA replication occurs in replication compartments that form in the nucleus by an ordered process involving a series of protein scaffold intermediates. Following entry of viral genomes into the nucleus, nucleoprotein complexes containing ICP4 can be detected at a position adjacent to nuclear domain 10 (ND10)-like bodies. ND10s are then disrupted by the viral E3 ubiquitin ligase ICP0. We have previously reported that after the dissociation of ND10-like bodies, ICP8 could be observed in a diffuse staining pattern; however, using more sensitive staining methods, we now report that in addition to diffuse staining, ICP8 can be detected in tiny foci adjacent to ICP4 foci. ICP8 microfoci contain UL9 and components of the helicase-primase complex. HSV infection also results in the reorganization of the heat shock cognate protein 70 (Hsc70) and the 20S proteasome into virus-induced chaperone-enriched (VICE) domains. In this report we show that VICE domains are distinct but adjacent to the ICP4 nucleoprotein complexes and the ICP8 microfoci. In cells infected with an ICP4 mutant virus encoding a mutant protein that cannot oligomerize on DNA, ICP8 microfoci are not detected; however, VICE domains could still be formed. These results suggest that oligomerization of ICP4 on viral DNA may be essential for the formation of ICP8 microfoci but not for the reorganization of host cell chaperones into VICE domains.
Mutations in the Amino Terminus of Foamy Virus Gag Disrupt Morphology and Infectivity but Do Not Target Assembly
Authors: Life Rachel B. , Lee Eun-Gyung , Eastman Scott W. , Linial Maxine L.
Published: April 2008

Foamy viruses (FVs) assemble using pathways distinct from those of orthoretroviruses. FV capsid assembly takes place near the host microtubule-organizing center (MTOC). Assembled capsids then migrate by an unknown mechanism to the trans-Golgi network to colocalize with the FV glycoprotein, Env. Interaction with Env is required for FV capsid egress from cells; the amino terminus of FV Gag contains a cytoplasmic targeting/retention signal that is responsible for targeting assembly to the MTOC. A mutant Gag was constructed by addition of a myristylation (M) signal in an attempt to target assembly to the plasma membrane and potentially overcome the dependence upon Env for budding (S. W. Eastman and M. L. Linial, J. Virol. 75:6857-6864, 2001). Using this and additional mutants, we now show that assembly is not redirected to the plasma membrane. Addition of an M signal leads to gross morphological defects. The aberrant particles still assemble near the MTOC but do not produce infectious virus. Although extracellular Gag can be detected in a pelletable form in the absence of Env, the mutant particles contain very little genomic RNA and are less dense. Our analyses indicate that the amino terminus of Gag contains an Env interaction domain that is critical for bona fide egress of assembled capsids.
Citrus Tristeza Virus
: Survival at the Edge of the Movement Continuum
Authors: Folimonova Svetlana Y. , Folimonov Alexey S. , Tatineni Satyanarayana , Dawson William O.
Published: April 2008

Systemic invasion of plants by viruses is thought to involve two processes: cell-to-cell movement between adjacent cells and long-distance movement that allows the virus to rapidly move through sieve elements and unload at the growing parts of the plant. There is a continuum of proportions of these processes that determines the degrees of systemic infection of different plants by different viruses. We examined the systemic distribution of
Citrus tristeza virus
(CTV) in citrus species with a range of susceptibilities. By using a “pure” culture of CTV from a cDNA clone and green fluorescent protein-labeled virus we show that both cell-to-cell and long-distance movement are unusually limited, and the degree of limitation varies depending on the citrus host. In the more-susceptible hosts CTV infected only a small portion of phloem-associated cells, and moreover, the number of infection sites in less-susceptible citrus species was substantially decreased further, indicating that long-distance movement was reduced in those hosts. Analysis of infection foci in the two most differential citrus species,
Citrus macrophylla
and sour orange, revealed that in the more-susceptible host the infection foci were composed of a cluster of multiple cells, while in the less-susceptible host infection foci were usually single cells, suggesting that essentially no cell-to-cell movement occurred in the latter host. Thus, CTV in sour orange represents a pattern of systemic infection in which the virus appears to function with only the long-distance movement mechanism, yet is able to survive in nature.
Human T-Cell Leukemia Virus Type 1 Tax Attenuates the ATM-Mediated Cellular DNA Damage Response
Authors: Chandhasin Chandtip , Ducu Razvan I. , Berkovich Elijahu , Kastan Michael B. , Marriott Susan J.
Published: April 2008

Genomic instability, a hallmark of leukemic cells, is associated with malfunctioning cellular responses to DNA damage caused by defective cell cycle checkpoints and/or DNA repair. Adult T-cell leukemia, which can result from infection with human T-cell leukemia virus type 1 (HTLV-1), is associated with extensive genomic instability that has been attributed to the viral oncoprotein Tax. How Tax influences cellular responses to DNA damage to mediate genomic instability, however, remains unclear. Therefore, we investigated the effect of Tax on cellular pathways involved in recognition and repair of DNA double-strand breaks. Premature attenuation of ATM kinase activity and reduced association of MDC1 with repair foci were observed in Tax-expressing cells. Following ionizing radiation-induced S-phase checkpoint activation, Tax-expressing cells progressed more rapidly than non-Tax-expressing cells toward DNA replication. These results demonstrate that Tax expression may allow premature DNA replication in the presence of genomic lesions. Attempts to replicate in the presence of these lesions would result in gradual accumulation of mutations, leading to genome instability and cellular transformation.
What happened to smokers’ beliefs about light cigarettes when “light/mild” brand descriptors were banned in the UK? Findings from the International Tobacco Control (ITC) Four Country Survey
Authors: Borland R , Fong G T , Yong H-H , Cummings K M , Hammond D , King B , Siahpush M , McNeill A , Hastings G , O’Connor R J , Elton-Marshall T , Zanna M P
Published: April 2008

Aim:

This paper examines how beliefs of smokers in the UK were affected by the removal of “light” and “mild” brand descriptors, which came into effect on 30 September 2003 for Member States of the European Union (EU).

Participants:

The data come from the first four waves (2002–2005) of the International Tobacco Control Policy Evaluation (ITC) Four-Country Survey, an annual cohort telephone survey of adult smokers in Canada, USA, UK and Australia (15 450 individual cases).

Design:

The UK ban on misleading descriptors occurred around the second wave of data collection in the ITC survey, permitting us to compare beliefs about light cigarettes among adult smokers in the UK before and after the ban, with beliefs in the three other ITC countries unaffected by the ban.

Results:

There was a substantial decline in reported beliefs about the benefits of light cigarettes in the UK following the policy change and an associated public information campaign, but by 2005 (ie, wave 4), these beliefs rebounded slightly and the change in beliefs was no greater than in the USA, where there was no policy change.

Conclusions:

The findings reveal that high levels of misperceptions about light cigarettes existed among smokers in all four countries before and after the EU ban took effect. We cannot conclude that the policy of removing some aspects of misleading labels has been effective in changing beliefs about light cigarettes. Efforts to correct decades of consumer misperceptions about light cigarettes must extend beyond simply removing “light” and “mild” brand descriptors.
Detection of Variability at Isozyme Loci in Sea Lamprey, Petromyzon marinus
Authors: Krueger Charles C.
Published: April 2008

Electrophoretic expression of 20 enzymes coded by a minimum of 30 gene loci is reported for sea lamprey. ADA, ADH, AGP, AAT, CPK, G6PDH, GAPDH, LDH, MDH, PEP, 6PGD, PGI, PGK, PGM, PK, PMI, and SDH yielded gel resolution satisfactory for use in future population studies. Six loci, AGP, MDH-1, PGI-1, PGI-2, PGM-1, and PMI were polymorphic. Enzyme expression did not vary between life stages (ammocoete vs. adult) or collection method (fresh frozen vs. TFM killed). Statistically significant genetic differences occurred between lamprey from Lake Superior, Oneida Lake, Lake Champlain, and Bay of Fundy drainages at one or more of the polymorphic loci.Key words: isozyme, lamprey, Petromyzon, electrophoresis, population identification, polymorphism
Blood Composition and Osmoregulation in Ammocoete Larvae
Authors: Morris Ron
Published: April 2008

Ammocoetes of all species are typical stenohaline freshwater animals which are able to regulate their blood and tissue ions very efficiently although they live in a very dilute environment. They excrete osmotic water by a well-developed kidney, and water turnover is high. Nephron units are sequentially arranged and have similar differentiated segments to those of other freshwater vertebrates. Total ion loss is low so the kidney must conserve ions efficiently. Ion loss is compensated by an ion-uptake mechanism, probably located in the interplatelet area of the gills. Here, the cells contain a sodium carrier whose transport rate is regulated by internal and external sodium levels; also they have mechanisms for potassium and chloride uptake. Both the gills and kidney have ion transport type cells, but the skin does not. The gills are probably the main access route for water, ions, and lampricides. The freshwater mechanism of osmoregulation persists beyond metamorphosis and thereafter many lampreys become euryhaline, but ammocoetes are unable to osmoregulate in hypertonic solutions and show passive responses. The adults of anadromous species like Lampetra fluviatilis and Petromyzon marinus develop a marine osmoregulatory mechanism which is similar to that of marine teleosts, whilst freshwater species like the landlocked P. marinus of the Great Lakes and the dwarf brook lamprey, Lampetra planeri, show reduced capacities for osmoregulation in seawater.Key words: ammocoetes, lampreys, osmoregulation, blood composition, gills, ion fluxes, kidney, urine, water fluxes, ion compartments