bluuebunny/crossref_metadata_2025 huggingface dataset:
Alcoholic extract of Cicer microphyllum augments Th1 immune response in normal and chronically stressed Swiss albino mice
Authors: Kour Kiranjeet , Sangwan Payare Lal Sangwan , Khan Imran , Koul Surrinder , Sharma Satya Narayan , Kitchlu Surinder , Bani Sarang
Published: November 2010

Objective

The purpose of this study was to observe the effect of an alcoholic extract of Cicer microphyllum (I3M/38/A001) (whole plant without seeds and flowers) on the immunological parameters of sheep red blood cell immunized normal and chronically stressed Swiss albino mice.

Methods

Estimation of T-cell subsets (CD3+, CD4+/CD8+), CD80/CD86, CD28, CD 69, costimulatory molecules and Th1/Th2 cytokines was carried out using a flow cytometer. This was followed by study of the delayed type hypersensitivity response, in-vitro lymphocyte proliferation assay and measurement of Th1/Th2 cytokines in isolated peripheral blood mononuclear cells by flow cytometry. An enzyme immune assay was used to analyse corticosterone levels in the serum of chronically stressed animals.

Key findings

We found that oral administration of I3M/38/A001once daily at the graded doses of 6.25, 12.5, 25, 50, 100 and 200 mg/kg p.o. enhanced the proliferation and differentiation of T lymphocytes in sheep red blood cell normal and chronically stressed mice, as shown by flow cytometric analysis. The extract selectively induced type 1 immunity: it guided enhanced expression of Th1 cytokines, interferon-γ and interleukin-2, while no significant change in interleukin-4 (Th2 cytokine) levels was observed. Confirmation of Th1 polarization was confirmed by the augmented levels of interferon-γ and interleukin-2 in isolated peripheral blood mononuclear cells. A significant suppression of raised corticosterone levels was also observed in stressed animals, which suggests the extract's normalizing effect on the hypothalamic–pituitary–adrenal axis. Co-stimulatory molecules, CD28, CD69, CD80 and CD86, which are important secondary signals for the activation of the immune system, elicited significant expression in I3M/38/A001 treated mice.

Conclusion

Our studies show the immune potentiating and immune recuperative effect of the test drug in sheep red blood cell-immunized normal and chronically stressed mice.
Low-level microbial contamination of liquid in syringe hubs leads to an unacceptable risk to the end product
Authors: Yusop Noorsuriani , Williams Gareth J , Cooper Callum , Burton Rachel , Samuel Lee , Maillard Jean-Yves
Published: November 2010

Objectives

The aim of this study was to assess the risk associated with microbial contamination in the hub-fluid in Luer-lock syringes to the end-product, and ultimately patients.

Methods

The hub-fluid of 48 sterile syringes prefilled with broth was contaminated with a low number of Staphylococcus epidermidis or spores of Bacillus subtilis. After incubation for three weeks, the syringe fills were tested for the presence of bacterial contaminants and some syringes were used to inoculate an end product broth that was then investigated for the presence of microorganisms.

Key findings

After three weeks of incubation only 20.8% of syringe fills showed turbidity, although following further investigation 70.8% were positive for the presence of viable bacteria, whereas 95.6% of end products became contaminated following injection of the syringe fill.

Conclusions

These findings add quantitative data that support the current practice of discarding syringes with residue around the cap.
Electrophysiological evidence for distinct vagal pathways mediating CCK‐evoked motor effects in the proximalversusdistal stomach
Authors: Okano‐Matsumoto Shiho , McRoberts James A. , Taché Yvette , Adelson David W.
Published: November 2010

Non‐technical summary

Gut activity is controlled by the vagus nerves. In anaesthetized rats, both sensory and motor nerve activity evoked by intravenous injection of the gut hormone cholecystokinin were recorded in separate sub‐branches of the gastric vagus nerve that supply the forestomach and hindstomach, respectively. Activity in the forestomach branch has not been studied before. Motor nerve activity in response to cholecystokinin differed between the two branches, in both timing and direction. Motor output to the forestomach paralleled sensory input from the hindstomach, while motor output to the hindstomach paralleled sensory input from the intestines. The data suggest that cholecystokinin released in the intestines after a meal immediately influences churning and propulsion of food by the hindstomach, via reflexes initiated by nearby intestinal sensory nerve terminals, but may influence gastric capacity only later, once circulating levels of cholecystokinin rise to levels capable of activating sensors in the hindstomach.
The dynamics of single spike‐evoked adenosine release in the cerebellum
Authors: Klyuch Boris P. , Richardson Magnus J. E. , Dale Nicholas , Wall Mark J.
Published: November 2010

Non‐technical summary

Adenosine modulates brain activity in both health and disease. Although we know a lot about adenosine action, we know little about how it is released and its cellular sources. We have previously shown that adenosine can be released in the cerebellum by a train of action potentials. Here we have used a pharmacological agent to enhance adenosine release and can thus study release in response to a single action potential. The release follows a waveform that is well described by a minimal diffusion model from a temporally sharp release event. Adenosine release has a complex, history‐dependent dynamics: it can be either depressed or enhanced depending on the stimulation pattern – similar properties to those of fast neurotransmitters such as glutamate. Our results demonstrate that the dynamics of adenosine release will depend strongly on the pattern of neural activity and thus constitutes a highly complex signalling pathway in the nervous system.
Irritating channels: the case of TRPA1
Authors: Nilius Bernd , Prenen Jean , Owsianik Grzegorz
Published: November 2010

Transient receptor potential (TRP) channels have been extensively studied over the past years. Yet, in most cases, the gating mechanisms of these polymodal cation channels still remain a puzzle. Using the nociceptive channel TRPA1 as an example, we discuss the role of dynamic regulation of the pore size (pore dilatation) on channel gating. Additionally, we critically revise current knowledge of the role of intracellular domains, such as ankyrin repeats and EF hand motifs, in channel activation and function. Finally, we assess some problems inherent to activation of TRPA1 by the reaction of electrophilic compounds with the nucleophilic thiol sink of N‐terminal reactive cysteines.
2D Viscous Aerodynamic Shape Design Optimization for Turbine Blades Based on Adjoint Method
Authors: Li Haitao , Song Liming , Li Yingchen , Feng Zhenping
Published: November 2010

This paper presents an adjoint optimization technique and its application to the design of a transonic turbine cascade. Capable of a quick and exact sensitivity analysis and using little computational resources, the adjoint method has been a focus of research in aerodynamic shape design optimization. The goal of this work is to extend the adjoint method into turbomachinery design applications for viscous and compressible flow, and to further improve the aerodynamic performance. In the work, the minimization of the entropy generation rate with the mass flow rate constraint was considered as the cost function of the optimization, and was applied in the direct design process. The adjoint boundary conditions of the corresponding cost function were derived in detail, using the nonslip boundary condition on the blade wall, while the flow viscous effect on the cascade inlet and outlet was neglected. Numerical techniques used in Computational Fluid Dynamics (CFD) were employed to solve the adjoint linear partial difference equations. With the solved adjoint variables, the final expression of the cost function gradient with respect to the design variables was formulated. Combined with quasi-Newton algorithm, an aerodynamic design approach based on the adjoint method for turbine blades was presented, which was independent of the Navier–Stokes solver being used. Finally, to validate the present optimization algorithm, the aerodynamic design cases of a transonic turbine blade with and without mass flow rate restriction were performed and analyzed.
Experimental Investigation of Thermal Load in High Speed Direct Injection Diesel Engine Under the Control of Various Engine Performance Parameters
Authors: Lee Jeonghoon
Published: November 2010

Multiple injection strategies are being widely utilized to reduce the vibration, noise, and particle emission in diesel engines. A considerable amount of research related to attempts to increase the maximum power and to reduce vibration, noise, and particulate matters has been done. However, investigations of various performance parameters in terms of the thermal load in high speed direct injection engines are rarely to be found despite the fact that the relationship between these parameters and the reliability of the engine is important for mass production. Hence, the thermal load imposed on the cylinder head and cylinder block of a four-cylinder diesel engine was investigated under the most severe test conditions, at the rated speed and with a full load, by changing the performance parameters such as the main injection timing, the fuel pressure in the common rail, the boost pressure, the exhaust gas recirculation, the fuel quantity of the pilot injection, the timing of the pilot injection, the fuel quantity of the postinjection, and the timing of postinjection. Experimental results showed that the main injection timing among other parameters was the parameter that influenced the thermal load most at the rated engine speed and under a full load condition.
Model-Based Actuator Trajectories Optimization for a Diesel Engine Using a Direct Method
Authors: Benz Michael , Hehn Markus , Onder Christopher H. , Guzzella Lino
Published: November 2010

This paper proposes a novel optimization method that allows a reduction in the pollutant emission of diesel engines during transient operation. The key idea is to synthesize optimal actuator commands using reliable models of the engine system and powerful numerical optimization methods. The engine model includes a mean-value engine model for the dynamics of the gas paths, including the turbocharger of the fuel injection, and of the torque generation. The pollutant formation is modeled using an extended quasi-static modeling approach. The optimization substantially changes the input signals, such that the engine model is enabled to extrapolate all relevant outputs beyond the regular operating area. A feedforward controller for the injected fuel mass is used to eliminate the nonlinear path constraints during the optimization. The model is validated using experimental data obtained on a transient engine test bench. A direct single shooting method is found to be most effective for the numerical optimization. The results show a significant potential for reducing the pollutant emissions during transient operation of the engine. The optimized input trajectories derived assist the design of sophisticated engine control systems.
An Investigation Into the Effects of Highly Transient Flight Maneuvers With Heat and Mass Transfer on the T-38 Air Force Trainer Inlet
Authors: Hale Alan , Hughes Andrew , Sirbaugh Jim , Kidman David S.
Published: November 2010

The T-38 talon currently serves as the primary United States Air Force trainer for fighter aircraft. This supersonic trainer was developed in the 1960s but continues to be used today as the result of various modernization programs throughout its service life. The latest propulsion modernization program focused on improved takeoff performance of the T-38’s inlets, improved reliability of the twin J85 afterburning turbojet engines, and reduced drag with an improved exhaust nozzle design. The T-38’s inlet includes bleed holes upstream of the engine face to provide cooling airflow from the inlet to the engine bay. However, at various flight conditions, the bay air is pressurized relative to the inlet, resulting in reverse flow of hot engine bay air into the inlet. This reverse flow causes total temperature distortion that may reduce the engine stability margin. Partial inlet instrumentation of the left engine was used to estimate the total temperature distortion associated with reverse flow, however, flight testing of highly transient maneuvers revealed levels of total temperature distortion greater than that predicted for reverse flow alone. This discovery led to the hypothesis that thermal energy storage of the aluminum inlet during transient flight maneuvers resulted in increased temperature distortion at the engine face. Flight data analysis demonstrated the need for a near-real-time thermal inlet distortion analysis capability. A two-dimensional (2D) transient axisymmetric heat and mass transfer model was developed through the use of a lumped-parameter boundary-layer model to simulate the inlet flow and determine the time-dependent inlet duct heat transfer. This model was validated with transient 2D computational fluid dynamics and two flight maneuvers. The analysis of flight maneuvers revealed that in the absence of engine bay air re-ingestion, the time lag associated with the heating and cooling of the inlet walls generates radial temperature distortion, which has the effect of reducing engine stability margin up to 5.44% for the maneuvers analyzed.
Measurements of Density Pulsations in the Outlet Nozzle of a Combustion Chamber by Rayleigh-Scattering Searching Entropy Waves
Authors: Rausch Anne , Fischer Andre , Konle Holger , Gaertlein Andrea , Nitsch Steffen , Knobloch Karsten , Bake Friedrich , Röhle Ingo
Published: November 2010

The development of measurement techniques, which enable temporal and spatial highly resolved density investigations even in harsh environments, is essential. Rayleigh scattering is a noninvasive optical measurement technique permitting such investigations. A Rayleigh-scattering measurement system is set up, providing a new insight into fluid mechanical processes in turbomachines. In this paper, Rayleigh scattering is used for the detection of density oscillations in the optical accessible convergent-divergent outlet nozzle of a small scale combustion test rig at various power consumptions and equivalence ratios. Until now, this part of the combustion chamber is sparsely investigated due to the challenging measurement conditions. The temporal density oscillation inside the nozzle can be shown up to 4 kHz as well as its spatial distribution. Systematic errors of the setup are investigated. Spectra of pressure and density oscillations are compared. Measurements with nonreacting air flow are conducted to study flow induced density fluctuations. Entropy noise related correlations between density and pressure fluctuations are found. Therewith, the builtup Rayleigh-scattering system enables investigations of the presumed region of indirect noise generation.
Effects of Swirl Velocities From Fan Assemblies Mounted on Lifting Surfaces
Authors: Terzis Alexandros , Kazakos Charilaos , Papadopoulos Nikolaos , Kalfas Anestis , Zachos Pavlos K. , Pilidis Pericles
Published: November 2010

The penetration of a jet of fluid into a traversal moving stream is a basic configuration of a wide range of engineering applications, such as film cooling and V/STOL aircrafts. This investigation examines experimentally the effect of blowing ratio of fans in crossflow, and numerically, the effect of the swirl velocity of jets in crossflow, downstream of the injection hole. The experimental results indicated an agreement with typically straight jets in crossflow (no vorticity), illustrating that the trace of the jet, remains close to the wall and subsequently enhance cooling at low blowing ratios in the case of turbine blade applications. However, the rotation of the jet results in an imparity between the two parts of the counter rotating vortex pair and as a consequence, the injected fluid not only bends in the direction of the main stream but also diverts in the direction of the rotation in order to conserve its angular momentum. The induction of the swirl velocity on the injected jet destructs one of the two parts of the kidney vortex, which entrains fluid from the crossflow to the jet promoting the mixing between the two fluids while the trace of a swirled jet remains closer to the wall downstream of the injection hole. Finally, the use of contrarotating jet or fan configurations reduces the wall shear stress in a very great extent, leading to better thermal protection of turbine blades, as well as cancels out the yaw torques of each fan separately, resulting in better flight control of typical lift surface.
A Test Rig for Noncontact Traveling Wave Excitation of a Bladed Disk With Underplatform Dampers
Authors: Berruti Teresa , Firrone Christian M. , Gola Muzio M.
Published: November 2010

This paper presents a static test rig called “Octopus” designed for the validation of numerical models aimed at calculating the nonlinear dynamic response of a bladed disk with underplatform dampers (UPDs). The test rig supports a bladed disk on a fixture and each UPD is pressed against the blade platforms by wires pulled by dead weights. Both excitation system and response measurement system are noncontacting. This paper features the design and the setup of the noncontacting excitation generated by electromagnets placed under each blade. A traveling wave excitation is generated according to a desired engine order by shifting the phase of the harmonic force of one electromagnet with respect to the contiguous exciters. Since the friction phenomenon generated by UPDs introduces nonlinearities on the forced response, the amplitude of the exciting force must be kept constant at a known value on every blade during step-sine test to calculate frequency response functions. The issue of the force control is therefore addressed since the performance of the electromagnet changes with frequency. The system calibration procedure and the estimated errors on the generated force are also presented. Examples of experimental tests that can be performed on a dummy integral bladed disk (blisk) mounted on the rig are described in the end.
Identification of Structural Stiffness and Energy Dissipation Parameters in a Second Generation Foil Bearing: Effect of Shaft Temperature
Authors: San Andrés Luis , Ryu Keun , Kim Tae Ho
Published: November 2010

Established high temperature operation of gas foil bearings (GFB) is of great interest for gas turbine applications. The effects of (high) shaft temperature on the structural stiffness and mechanical energy dissipation parameters of a foil bearing (FB) must be assessed experimentally. Presently, a hollow shaft warmed by an electric heater holds a floating second generation FB that is loaded dynamically by an electromagnetic shaker. In tests with the shaft temperature up to 184°C, the measurements of dynamic load and ensuing FB deflection render the bearing structural parameters, stiffness and damping, as a function of excitation frequency and amplitude of motion. The identified FB stiffness and viscous damping coefficients increase with shaft temperature due to an increase in the FB assembly interference or preload. The bearing material structural loss factor best representing mechanical energy dissipation decreases slightly with shaft temperature while increasing with excitation frequency. Separate static load measurements on the bearing also make evident the preload of the test bearing-shaft system at room temperature. The loss factor obtained from the area inside the hysteresis loop of the static load versus the deflection curve agrees remarkably with the loss factor obtained from the dynamic load measurements. The static procedure offers substantial savings in cost and time to determine the energy dissipation characteristics of foil bearings. Post-test inspection of the FB reveals sustained wear at the locations, where the bumps contact the top foil and the bearing sleeve inner surface, thus, evidences the bearing energy dissipation by dry friction.
Modeling of Ultrafast Phase Change Processes in a Thin Metal Film Irradiated by Femtosecond Laser Pulse Trains
Authors: Huang Jing , Zhang Yuwen , Chen J. K. , Yang Mo
Published: November 2010

Ultrashort laser pulses can be generated in the form of a pulse train. In this paper, the ultrafast phase change processes of a 1 μm free-standing gold film irradiated by femtosecond laser pulse trains are simulated numerically. A two-temperature model coupled with interface tracking method is developed to describe the ultrafast melting, vaporization, and resolidification processes. To deal with the large span in time scale, variable time steps are adopted. A laser pulse train consists of several pulse bursts with a repetition rate of 0.5–1 MHz. Each pulse burst contains 3–10 pulses with an interval of 50 ps–10 ns. The simulation results show that with such configuration, to achieve the same melting depth, the maximum temperature in the film decreases significantly in comparison to that of a single pulse. Although the total energy depositing on the film will be lifted, more energy will be transferred into the deeper part, instead of accumulating in the subsurface layer. This leads to lower temperature and temperature gradient, which is favorable in laser sintering and laser machining.
Modeling of the Off-Axis High Power Diode Laser Cladding Process
Authors: Wen Shaoyi , Shin Yung C.
Published: November 2010

Off-axis high power diode laser (HPDL) cladding is commonly used for surface quality enhancement such as coating, part repairing, etc. Although some laser cladding models are available in literature, little has been reported on the modeling of powder flow and molten pool for a rectangular beam with side powder injection. In this article, a custom-designed flat nozzle delivers the powder material into a distinct molten pool formed by a HPDL with a rectangular beam. A powder model is first presented to reveal the powder flow behavior below the flat nozzle. Key parameters such as nozzle inclination angle, rectangular beam profile, shielding gas flow rates, and powder feed rate are incorporated so that spatial powder density, powder velocity, and temperature distribution are distinctly investigated. Then in order to describe thermal and fluidic behaviors around the molten pool formed by the rectangular beam, a three-dimensional self-consistent cladding model is developed with the incorporation of the distributed powder properties as input. The level set method is adopted to track the complex free surface evolution. Temperature fields and fluid motion in the molten pool area resulting from the profile of rectangular beam are distinctly revealed. The effect of continuous mass addition is also embedded into the governing equations, making the model more accurate. A HPDL cladding with little dilution is formed and the simulated results agree well with the experiment.
Single-Phase Thermal Transport of Nanofluids in a Minichannel
Authors: Liu Dong , Yu Leyuan
Published: November 2010

Nanofluids have been proposed as a promising candidate for advanced heat transfer fluids in a variety of important engineering applications ranging from energy storage and electronics cooling to thermal processing of materials. In spite of the extensive studies in the literature, a consensus is lacking on if and how the dispersed nanoparticles alter the thermal transport in convective flows. In this work, an experimental investigation was conducted to study single-phase forced convection of Al2O3-water nanofluid in a circular minichannel with a 1.09 mm inner diameter. The friction factor and convection heat transfer coefficients were measured for nanofluids of various volume concentrations (up to 5%) and were compared with those of the base fluid. The Reynolds number (Re) varied from 600 to 4500, covering the laminar, transition, and early fully developed turbulent regions. It was found that in the laminar region, the nanofluids exhibit pronounced entrance region behaviors possibly due to the flattening of the velocity profile caused by the flow-induced particle migration. Three new observations were made for nanofluids in the transition and turbulent regions: (1) The onset of transition to turbulence is delayed; (2) both the friction factor and the convective heat transfer coefficient are below those of water at the same Re in the transition flow; and (3) once fully developed turbulence is established, the difference in the flow and heat transfer of nanofluids and water will diminish. A simple scaling analysis was used to show that these behaviors may be attributed to the variation in the relative size of the nanoparticle with respect to the turbulent microscales at different Re. The results from this work suggest that the particle-fluid interaction has a significant impact on the flow physics of nanofluids, especially in the transition and turbulent regions. Consequently, as a heat transfer fluid, nanofluids should be used in either the laminar flow or the fully developed turbulent flow at sufficiently high Re in order to yield enhanced heat transfer performance.
Activation of STIM1-Orai1 Involves an Intramolecular Switching Mechanism
Authors: Korzeniowski Marek K. , Manjarrés Isabel Martín , Varnai Peter , Balla Tamas
Published: November 2010

A cytoplasmic domain in STIM1 acts as a decoy to block the ability of STIM1 to bind to and activate Orai1.
Flow into a New Cell Size
Authors: Wong Wei
Published: November 2010

Fluid flow activates the LKB1-AMPK pathway in cilia to inhibit mTORC1-mediated increases in cell size.
Fungal Invasion or Pollination?
Authors: Hines Pamela J.
Published: November 2010

In
Arabidopsis
, development and disease use the same pollen-tube or hyphal tip-growing strategies.
Plumbing in the Brain
Authors: Hines Pamela J.
Published: November 2010

A factor is identified that determines the amount of vasculature in the brain and, in doing so, affects brain function.
Roles of Residues Cys69, Asn104, Phe160, Gly232, Ser237, and Asp240 in Extended-Spectrum β-Lactamase Toho-1
Authors: Shimizu-Ibuka Akiko , Oishi Mika , Yamada Shoko , Ishii Yoshikazu , Mura Kiyoshi , Sakai Hiroshi , Matsuzawa Hiroshi
Published: November 2010

Toho-1, which is also designated CTX-M-44, is an extended-spectrum class A β-lactamase that has high activity toward cefotaxime. In this study, we investigated the roles of residues suggested to be critical for the substrate specificity expansion of Toho-1 in previous structural analyses. Six amino acid residues were replaced one by one with amino acids that are often observed in the corresponding position of non-extended-spectrum β-lactamases. The mutants produced in
Escherichia coli
strains were analyzed both for their kinetic properties and their effect on drug susceptibilities. The results indicate that the substitutions of Asn104 and Ser237 have certain effects on expansion of substrate specificity, while those of Cys69 and Phe160 have less effect, and that of Asp240 has no effect on the hydrolysis of any substrates tested. Gly232, which had been assumed to increase the flexibility of the substrate binding site, was revealed not to be critical for the expansion of substrate specificity of this enzyme, although this substitution resulted in deleterious effects on expression and stability of the enzyme.
Determination of the Duration of Antibacterial Efficacy following Administration of Gamithromycin Using a Bovine
Mannheimia haemolytica
Challenge Model
Authors: Forbes A. B. , Ramage C. , Sales J. , Baggott D. , Donachie W.
Published: November 2010

The antibacterial efficacy of gamithromycin administered once 1, 5, or 10 days prior to a challenge infection with
Mannheimia haemolytica
serotype A1 was evaluated. Forty calves were randomly allocated on day −11, restricted by body weight, to one of three treatment groups given gamithromycin at 6 mg/kg of body weight 10, 5, or 1 days before challenge or to an untreated control group.
M. haemolytica
A1 challenge infections were induced on day 0 by depositing 7.4 × 10
7
CFU at the bifurcation of the main bronchus using a bronchoscope. Clinical observations were made daily from the day of allocation to day 10, when necropsy was scheduled; three calves died or were euthanized
in extremis
on welfare grounds prior to scheduled necropsy. At necropsy the lungs were removed, pneumonic lesions were scored, and samples of lung tissue were cultured for
M. haemolytica
. The three groups of animals treated with gamithromycin before challenge had significantly lower lung
M. haemolytica
counts and fewer clinical signs of respiratory disease than did the saline-treated group. For most of the clinical parameters, the pattern of responses differed significantly (
P
< 0.05) between the gamithromycin-treated groups and the control group. There were no statistically significant differences between groups in the mean lung lesion scores, partly as a result of high individual variability, particularly within the control group. The administration of gamithromycin 1, 5, and 10 days prior to
M. haemolytica
A1 challenge resulted in a reduction in bacterial isolation from the lungs and a reduction in the severity of clinical disease.
High-ThroughputGiardia lambliaViability Assay Using Bioluminescent ATP Content Measurements
Authors: Chen Catherine Z. , Kulakova Liudmila , Southall Noel , Marugan Juan J. , Galkin Andrey , Austin Christopher P. , Herzberg Osnat , Zheng Wei
Published: November 2010

The human pathogenGiardia lambliais an anaerobic protozoan parasite that causes giardiasis, one of the most common diarrheal diseases worldwide. Although several drugs are available for the treatment of giardiasis, drug resistance has been reported and is likely to increase, and recurrent infections are common. The search for new drugs that can overcome the drug-resistant strains ofGiardiais an unmet medical need. New drug screen methods can facilitate the drug discovery process and aid with the identification of new drug targets. Using a bioluminescent ATP content assay, we have developed a phenotypic drug screen method to identify compounds that act against the actively growing trophozoite stage of the parasite. This assay is homogeneous, robust, and suitable for high-throughput screening of large compound collections. A screen of 4,096 pharmacologically active small molecules and approved drugs revealed 43 compounds with selective anti-Giardiaproperties, including 32 previously reported and 11 novel anti-Giardiaagents. The most potent novel compound was fumagillin, which showed 50% inhibitory concentrations of 10 nM against the WB isolate and 2 nM against the GS isolate.
Mechanisms Mediating Bactericidal Properties and Conditions That Enhance the Potency of a Broad-Spectrum Oligo-Acyl-Lysyl
Authors: Sarig Hadar , Goldfeder Yair , Rotem Shahar , Mor Amram
Published: November 2010

Previous studies have established the potential of the oligo-acyl-lysyl (OAK) concept in generating simple chemical mimics of host defense peptides (HDPs) with improved antimicrobial properties. We investigated the antibacterial properties of such an OAK, C16(ω7)-KK-C12-Kamide, to obtain a better understanding of the complex mode(s) of action of cationic antibacterial peptides. The average MIC, determined against a multispecies panel of 50 strains, was 6 ± 5 μg/ml. However, although the OAK exerted an essentially dose-dependent bactericidal effect (time-kill curves typically exhibited 99% death within 2 h), marked differences in the killing rates occurred among inter- and intraspecies strains. Mechanistic comparison between equally sensitive and related strains revealed death of one strain to stem from the OAK's capacity to breach the cell membrane permeability barrier, whereas the death of the related strain resulted from the OAK's direct interference with DNA functionsin vivo, without detectable membrane damage. These findings therefore support the notion that the antibacterial mechanism of action of a single HDP can vary among inter- and intraspecies strains. In addition, we present data illustrating the differential effects of environmental conditions (pH, ionic strength and temperature), on the OAK's antibacterial properties, and ultimately demonstrate potency enhancement (by orders of magnitude) through selection of optimal incubation conditions. Such attributes might be useful in a variety of antibacterial applications.
Antiviral Activity, Pharmacokinetics, and Safety of BMS-488043, a Novel Oral Small-Molecule HIV-1 Attachment Inhibitor, in HIV-1-Infected Subjects
Authors: Hanna George J. , Lalezari Jacob , Hellinger James A. , Wohl David A. , Nettles Richard , Persson Anna , Krystal Mark , Lin Pinfang , Colonno Richard , Grasela Dennis M.
Published: November 2010

BMS-488043 is a novel and unique oral small-molecule inhibitor of the attachment of human immunodeficiency virus type 1 (HIV-1) to CD4
+
lymphocytes. The antiviral activity, pharmacokinetics, viral susceptibility, and safety of BMS-488043 were evaluated in an 8-day monotherapy trial. Thirty HIV-1-infected study subjects were randomly assigned to sequential, safety-guided dose panels of 800 and 1,800 mg BMS-488043 or a matched placebo in a 4:1 ratio, and the drug was administered every 12 h with a high-fat meal for 7 days and on the morning of day 8. Dose-related, albeit less-than-dose-proportional, increases in plasma BMS-488043 concentrations were observed. Mean plasma HIV-1 RNA decreases from the baseline for the BMS-488043 800- and 1,800-mg dose groups on day 8 were 0.72 and 0.96 log
10
copies/ml, respectively, compared with 0.02 log
10
copies/ml for the placebo group. A lower baseline BMS-488043 50% effective concentration (EC
50
) in the active-treatment groups was predictive of a greater antiviral response. Although absolute drug exposure was not associated with an antiviral response, the trough concentration (
C
trough
), adjusted by the baseline EC
50
(
C
trough
/EC
50
), was associated with antiviral activity. During dosing, four subjects experienced >10-fold reductions in viral susceptibility to BMS-488043, providing further support of the direct antiviral mechanism of BMS-488043. BMS-488043 was generally safe and well tolerated. These results suggest that further development of this novel class of oral HIV-1 attachment inhibitors is warranted.
Pharmacodynamics of Telavancin Studied in an
In Vitro
Pharmacokinetic Model of Infection
Authors: MacGowan Alasdair P. , Noel Alan R. , Tomaselli Sharon , Elliott Heather C. , Bowker Karen E.
Published: November 2010

The antibacterial effects of telavancin, vancomycin, and teicoplanin against six
Staphylococcus aureus
strains (1 methicillin-susceptible
S. aureus
[MSSA] strain, 4 methicillin-resistant
S. aureus
[MRSA] strains, and 1 vancomycin-intermediate
S. aureus
[VISA] strain) and three
Enterococcus
sp. strains (1
Enterococcus faecalis
strain, 1
Enterococcus faecium
strain, and 1 vancomycin-resistant
E. faecium
[VREF] strain) were compared using an
in vitro
pharmacokinetic model of infection. Analyzing the data from all five vancomycin-susceptible
S. aureus
(VSSA) strains or all 4 MRSA strains showed that telavancin was superior in its antibacterial effect as measured by the area under the bacterial kill curve at 24 h (AUBKC
24
) and 48 h (AUBKC
48
) in comparison to vancomycin or teicoplanin (
P
< 0.05). Telavancin was also superior to vancomycin and teicoplanin in terms of its greater early killing effect (
P
< 0.05). Against the three
Enterococcus
spp. tested, telavancin was superior to vancomycin in terms of its AUBKC
24
, AUBKC
48
, and greater early bactericidal effect (
P
< 0.05). Dose-ranging studies were performed to provide free-drug area under the concentration-time curve over 24 h in the steady state divided by the MIC (fAUC/MIC) exposures from 0 to 1,617 (7 to 14 exposures per strain) for 5 VSSA, 4 VISA, and the 3
Enterococcus
strains. The fAUC/MIC values for a 24-h bacteriostatic effect and a 1-log-unit drop in the viable count were 43.1 ± 38.4 and 50.0 ± 39.0 for VSSA, 3.2 ± 1.3 and 4.3 ± 1.3 for VISA, and 15.1 ± 8.8 and 40.1 ± 29.4 for the
Enterococcus
spp., respectively. The reason for the paradoxically low fAUC/MIC values for VISA strains is unknown. There was emergence of resistance to telavancin in the dose-ranging studies, as indicated by subpopulations able to grow on plates containing 2× MIC telavancin concentrations compared to the preexposure population analysis profiles. Changes in population analysis profiles were less likely with enterococci than with
S. aureus
, and the greatest risk of changed profiles occurred for both species at fAUC/MIC ratios of 1 to 10. Maintaining a fAUC/MIC ratio of >50 reduced the risk of subpopulations able to grow on antibiotic-containing media emerging. These data help explain the clinical effectiveness of telavancin against MRSA and indicate that telavancin may have clinically useful activity against
Enterococcus
spp., and perhaps also VISA, at human doses of 10 mg/kg of body weight/day. In addition, they support a clinical breakpoint of sensitive at ≤1 mg/liter for both
S. aureus
and
Enterococcus
spp.
Limited Ability ofPlasmodium falciparum pfcrt,pfmdr1, andpfnhe1Polymorphisms To Predict QuinineIn VitroSensitivity or Clinical Effectiveness in Uganda
Authors: Baliraine Frederick N. , Nsobya Samuel L. , Achan Jane , Tibenderana James K. , Talisuna Ambrose O. , Greenhouse Bryan , Rosenthal Philip J.
Published: November 2010

Quinine is a standard drug for treating severe malaria in Africa, and it is also increasingly used to treat uncomplicated disease. However, failures of quinine therapy are common, and it is unknown if failures in Africa are due to drug resistance. Recent studies have identified associations betweenin vitroquinine sensitivity and polymorphisms in genes encoding putative transporters, including well-described polymorphisms inpfcrtandpfmdr1and varied numbers of DNNND or DDNHNDNHNND repeats in microsatellite 4760 (ms4760) of the predicted sodium-hydrogen exchanger,pfnhe1. To better characterize mediators of quinine response, we assessed associations between genetic polymorphisms,in vitroquinine sensitivity, and quinine treatment responses in Kampala, Uganda. Among 172 fresh clinical isolates testedin vitro, decreasing sensitivity to quinine was associated with accumulation ofpfmdr1mutations at codons 86, 184, and 1246. Nearly all parasites hadpfcrt76T, preventing analysis of associations with this mutation.pfnhe1ms4760 was highly polymorphic. Parasites with 2 copies of either ms4760 repeat showed modest decreases in quinine sensitivity compared to those with 1 or ≥3 repeats, but the differences were not statistically significant. None of the above polymorphisms predicted treatment failure among 66 subjects treated with quinine for uncomplicated malaria. Our data suggest that quinine sensitivity is a complex trait and that known polymorphisms inpfcrt,pfmdr1, andpfnhe1, while associated with quinine sensitivity, are not robust markers for quinine resistance.
Oral Hexadecyloxypropyl-Cidofovir Therapy in Pregnant Guinea Pigs Improves Outcome in the Congenital Model of Cytomegalovirus Infection
Authors: Bravo Fernando J. , Bernstein David I. , Beadle James R. , Hostetler Karl Y. , Cardin Rhonda D.
Published: November 2010

Cytomegalovirus (CMV) infection is the leading cause of congenital infection, producing both sensorineural hearing loss and mental retardation. We evaluated thein vivoefficacy of an orally bioavailable analog of cidofovir, hexadecyloxypropyl-cidofovir (HDP-CDV), against guinea pig CMV (GPCMV) in a guinea pig model of congenital CMV infection. HDP-CDV exhibited antiviral activity against GPCMV with a 50% effective concentration (EC50) of 0.004 μM ± 0.001 μM. To evaluatein vivoefficacy, pregnant Hartley guinea pigs were inoculated with GPCMV during the late second/early third trimester of gestation. Animals were administered 20 mg HDP-CDV/kg body weight orally at 24 h postinfection (hpi) and again at 7 days postinfection (dpi) or administered 4 mg/kg HDP-CDV orally each day for 5 days or 9 days. Virus levels in dam and pup tissues were evaluated following delivery, or levels from dam, placenta, and fetal tissues were evaluated following sacrifice of dams at 10 dpi. All HDP-CDV regimens significantly improved pup survival, from 50 to 60% in control animals to 93 to 100% in treated animals (P≤ 0.019). Treatment with 20 mg/kg HDP-CDV significantly reduced the viral load in pup spleen (P= 0.017) and liver (P= 0.029). Virus levels in the placenta were significantly reduced at 10 dpi following daily treatment with 4 mg/kg HDP-CDV for 5 or 9 days. The 9-day treatment also significantly reduced the viral levels in the dam spleen and liver. Although the 4-mg/kg treatment improved pup survival, virus levels in the fetal tissues were similar to those in control tissues. Taken together, HDP-CDV shows potential as a well-tolerated antiviral candidate for treatment of congenital human CMV (HCMV) infection.
Cold Shock Induces
qnrA
Expression in
Shewanella algae
Authors: Kim Hong Bin , Park Chi Hye , Gavin Mariah , Jacoby George A. , Hooper David C.
Published: November 2010

Plasmid-carried quinolone resistance genes, like
qnrA
, are widespread in
Enterobacteriaceae
. To gain insight into its little-understood native functions, we studied the effect of environmental conditions on chromosomal
qnrA
expression in
Shewanella algae
. Among conditions of DNA damage, oxidative and osmotic stress, starvation, heat, and cold, only cold shock increased gene expression, as measured by quantitative reverse transcription-PCR (qRT-PCR). Induction was graded and occurred during growth arrest, suggesting that
qnrA
may contribute to the adaptation of
Shewanella
to low temperatures.
Systematic Review and Meta-Analysis of the Significance of Heterogeneous Vancomycin-Intermediate
Staphylococcus aureus
Isolates
Authors: van Hal Sebastiaan J. , Paterson David L.
Published: November 2010

The prevalence of heteroresistant vancomycin-intermediate
Staphylococcus aureus
(hVISA) is 1.3% in published studies. Clinical associations include high-inoculum infections and glycopeptide failure, with hVISA infections associated with a 2.37-times-greater failure rate (95% confidence interval [CI], 1.53 to 3.67) compared to vancomycin-sensitive
Staphylococcus aureus
(VSSA) infections. Despite this, 30-day mortality rates were similar to those for VSSA infections (odds ratio [OR], 1.18; 95% CI, 0.81 to 1.74). The optimal therapy for hVISA requires further study.
In Vivo
Patterns of Resistance to the HIV Attachment Inhibitor BMS-488043
Authors: Zhou Nannan , Nowicka-Sans Beata , Zhang Sharon , Fan Li , Fang Jie , Fang Hua , Gong Yi-Fei , Eggers Betsy , Langley David R. , Wang Tao , Kadow John , Grasela Dennis , Hanna George J. , Alexander Louis , Colonno Richard , Krystal Mark , Lin Pin-Fang
Published: November 2010

Attachment inhibitors (AI) are a novel class of HIV-1 antivirals, with little information available on clinical resistance. BMS-488043 is an orally bioavailable AI that binds to gp120 of HIV-1 and abrogates its binding to CD4
+
lymphocytes. A clinical proof-of-concept study of the AI BMS-488043, administered as monotherapy for 8 days, demonstrated significant viral load reductions. In order to examine the effects of AI monotherapy on HIV-1 sensitivity, phenotypic sensitivity assessment of baseline and postdosing (day 8) samples was performed. These analyses revealed that four subjects had emergent phenotypic resistance (a 50% effective concentration [EC
50
] >10-fold greater than the baseline value) and four had high baseline EC
50
s (>200 nM). Population sequencing and sequence determination of cloned envelope genes uncovered five gp120 mutations at four loci (V68A, L116I, S375I/N, and M426L) associated with BMS-488043 resistance. Substitution at the 375 locus, located near the CD4 binding pocket, was the most common (maintained in 5/8 subjects at day 8). The five substitutions were evaluated for their effects on AI sensitivity through reverse genetics in functional envelopes, confirming their role in decreasing sensitivity to the drug. Additional analyses revealed that these substitutions did not alter sensitivity to other HIV-1 entry inhibitors. Thus, our studies demonstrate that although the majority of the subjects' viruses maintained sensitivity to BMS-488043, substitutions can be selected that decrease HIV-1 susceptibility to the AI. Most importantly, the substitutions described here are not associated with resistance to other approved antiretrovirals, and therefore, attachment inhibitors could complement the current arsenal of anti-HIV agents.
Biomarker-Assisted Dose Selection for Safety and Efficacy in Early Development of PNU-100480 for Tuberculosis
Authors: Wallis Robert S. , Jakubiec Wesley , Kumar Vikas , Bedarida Gabriella , Silvia Annette , Paige Darcy , Zhu Tong , Mitton-Fry Mark , Ladutko Lynn , Campbell Sheldon , Miller Paul F.
Published: November 2010

Tuberculosis is a serious global health threat for which new treatments are urgently needed. This study examined the safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple ascending doses of the oxazolidinone PNU-100480 in healthy volunteers, using biomarkers for safety and efficacy. Subjects were randomly assigned to PNU-100480 or placebo (4:1) at schedules of 100, 300, or 600 mg twice daily or 1,200 mg daily for 14 days or a schedule of 600 mg twice daily for 28 days to which pyrazinamide was added on days 27 and 28. A sixth cohort was given linezolid at 300 mg daily for 4 days. Signs, symptoms, and routine safety tests were monitored. Bactericidal activity against
Mycobacterium tuberculosis
was measured in
ex vivo
whole-blood culture. Plasma drug and metabolite concentrations were compared to the levels required for inhibition of
M. tuberculosis
growth and 50% inhibition of mitochondrial protein synthesis. All doses were safe and well tolerated. There were no hematologic or other safety signals during 28 days of dosing at 600 mg twice daily. Plasma concentrations of PNU-100480 and metabolites at this dose remained below those required for 50% inhibition of mitochondrial protein synthesis. Cumulative whole-blood bactericidal activity of PNU-100480 at this dose (−0.316 ± 0.04 log) was superior to the activities of all other doses tested (
P
< 0.001) and was significantly augmented by pyrazinamide (−0.420 ± 0.06 log) (
P
= 0.002). In conclusion, PNU-100480 was safe and well tolerated at all tested doses. Further studies in patients with tuberculosis are warranted. Biomarkers can accelerate early development of new tuberculosis treatments.