bluuebunny/crossref_metadata_2025 huggingface dataset:
The Structure of Wall-Impinging Jets: Computed Versus Theoretical and Measured Results
Authors: Song Lijun , Abraham John
Published: January 2004

In this work, the structure of computed wall-impinging gas jets is compared with theoretical and experimental results presented in the literature. The computational study employs the k-ε model to represent turbulence. Wall functions are employed to model momentum transfer at the walls. The computed penetration and growth rate of the jet agree with measured and analytical results within 10%. Computed radial velocities in the developed region of the wall jet are self-similar as found in prior experimental and analytical works. The computed radial velocity profile and quantitative values in the outer layer of the jet and the location of the maximum radial velocity agree within 5% with measurements and analytical results. Greater quantitative differences are found in the near-wall region. Mixing characteristics of a wall-impinging jet are compared with those of a round free jet. The wall-impinging jet mixes slower than the round free jet.
Numerical Simulation of Two-Phase Flow in Injection Nozzles: Interaction of Cavitation and External Jet Formation
Authors: Yuan Weixing , Schnerr Gu¨nter H.
Published: January 2004

The present investigation demonstrates the strong interaction of cavitating nozzle flow with the outside jet formation. Due to the strong sensitivity of cavitation on the imposed boundary conditions, simulations with restriction on the internal problem are qualitatively and quantitatively incorrect, so that phenomena like hydraulic flip and supercavitation cannot be revealed. Our results indicate the potential of cavitation for enhancement of atomization and spray quality.
Mapping of the Lateral Flow Field in Typical Subchannels of a Support Grid With Vanes
Authors: McClusky Heather L. , Holloway Mary V. , Conover Timothy A. , Beasley Donald E. , Conner Michael E. , Smith L. David
Published: January 2004

Lateral flow fields in four subchannels of a model rod bundle fuel assembly are experimentally measured using particle image velocimetry. Vanes (split-vane pairs) are located on the downstream edge of the support grids in the rod bundle fuel assembly and generate swirling flow. Measurements are acquired at a nominal Reynolds number of 28,000 and for seven streamwise locations ranging from 1.4 to 17.0 hydraulic diameters downstream of the grid. The streamwise development of the lateral flow field is divided into two regions based on the lateral flow structure. In Region I, multiple vortices are present in the flow field and vortex interactions occur. Either a single circular vortex or a hairpin shaped flow structure is formed in Region II. Lateral kinetic energy, maximum lateral velocity, centroid of vorticity, radial profiles of azimuthal velocity, and angular momentum are employed as measures of the streamwise development of the lateral flow field. The particle image velocimetry measurements of the present study are compared with laser Doppler velocimetry measurements taken for the identical support grids and flow condition.
Swing Check Valve Characterization and Modeling During Transients
Authors: Li Guohua , Liou Jim C. P.
Published: January 2004

The hydraulic torque on the disk of a swing check valve strongly influences the dynamic valve-fluid interaction. This torque is difficult to quantify. In this study, the hydraulic torque is separated into a torque due to flow around a stationary disk and a torque due to disk rotation. Laboratory tests have been conducted to characterize these components. Numerical simulations of a check valve slam are made and the results compared with measured disk angle and pressure traces. The validity of the hydraulic torque characterization is demonstrated by the close agreement between the simulation results and the measurements.
Numerical Simulations of Flows Inside a Partially Filled Centrifuge
Authors: Yan Fang , Farouk Bakhtier
Published: January 2004

A numerical study was conducted to predict the dynamics of gas/liquid flows in a partially filled cylinder undergoing moderate to rapid rotation. Two specific problems were considered: spinup from rest of a partially filled circular container and the steady flow field in a partially filled rotating circular cylinder with an overrotating lid. Numerical solutions of the time-dependent axisymmetric Navier-Stokes equations were obtained by using a homogeneous multiphase model. The evolution of the free surface along with the flow fields in both the gas and liquid phases are predicted. The computed results were compared with available experimental data. Details of flow field structures are examined by studying the numerical solutions. Radial profiles of axial and azimuthal velocities for both the liquid and gas phases are also presented. The model developed can be used for analyzing flows and mixing problems in complex-geometry centrifuges.
Development of a Steady Vortex Generator Jet in a Turbulent Boundary Layer
Authors: Rixon Gregory S. , Johari Hamid
Published: January 2004

The development of a vortex generator jet within a turbulent boundary layer was studied by the particle image velocimetry method. Jet velocities ranging from one to three times greater than the freestream velocity were examined. The jet was pitched 45 deg and skewed 90 deg with respect to the surface and flow direction, respectively. The velocity field in planes normal to the freestream was measured at four stations downstream of the jet exit. The jet created a pair of streamwise vortices, one of which was stronger and dominated the flow field. The circulation, peak vorticity, and wall-normal position of the primary vortex increased linearly with the jet velocity. The circulation and peak vorticity decreased exponentially with the distance from the jet source for the jet-to-freestream velocity ratios of 2 and 3. The wandering of the streamwise vortex can be as much as ±30% of the local boundary layer thickness at the farthest measurement station.
Magnetohydrodynamic Viscous Flow Separation in a Channel With Constrictions
Authors: Midya C. , Layek G. C. , Gupta A. S. , Mahapatra T. Ray
Published: January 2004

An analysis is made of the flow of an electrically conducting fluid in a channel with constrictions in the presence of a uniform transverse magnetic field. A solution technique for governing magnetohydrodynamic (MHD) equations in primitive variable formulation is developed. A coordinate stretching is used to map the long irregular geometry into a finite computational domain. The governing equations are discretized using finite difference approximations and the well-known staggered grid of Harlow and Welch is used. Pressure Poisson equation and pressure-velocity correction formulas are derived and solved numerically. It is found that the flow separates downstream of the constriction. With increase in the magnetic field, the flow separation zone diminishes in size and for large magnetic field, the separation zone disappears completely. Wall shear stress increases with increase in the magnetic field strength. It is also found that for symmetrically situated constrictions on the channel walls, the critical Reynolds number for the flow bifurcation (i.e., flow asymmetry) increases with increase in the magnetic field.
Anisotropic Strength Approach for Wear Analysis of Unidirectional Continuous FRP Composites
Authors: Ning Xinguo , Lovell Michael R. , Morrow Clint
Published: January 2004

Based on the anisotropic strength failure criteria, a model is introduced to predict the wear behavior of unidirectional continuous fiber reinforced polymer composites (FRP) for arbitrary fiber orientations. This approach, which includes the influence of the friction on the failure strength, is initially validated by comparison to experimental data for T300/Epoxy. The benefits of the model and trends for variation of wear with fiber orientations are subsequently ascertained and discussed.
Analysis of the Tribological Mechanisms Arising in the Chemical Mechanical Polishing of Copper-Film Wafers
Authors: Lin Jen Fin , Chern Junne Dar , Chang Yang Hui , Kuo Ping Lin , Tsai Ming Shih
Published: January 2004

In the chemical mechanical planarization of a copper-film silicon wafer, the average Reynolds equation with flow factors has also been developed for a cylindrical coordinate system to study the mixed lubrication. The pad’s elastic deformations are considered in the evaluation of the contact pressure arising at the interface of a pad’s asperity and the wafer. The normal force acting on the wafer by an abrasive particle is thus obtained in order to calculate the elastic and plastic deformations of the copper film with a thin passivation layer. A theoretical abrasive wear model is developed to evaluate the removal rate of the copper film. The increase in the real contact area of an abrasive, due to the frictional force produced at the interface by adhesive wear, is also taken into account. A nano tester was applied to measure the composite hardness and Young’s modulus of the copper-film wafer with a passivation layer. These two material properties are of importance in the calculation of wafer’s theoretical removal rate. Experimental results for the removal rates of the copper film are exhibited to compare with that predicted by the present theoretical model. Fairly good agreement exists in the trends of the removal rates varying in the radial direction and the mean removal rates evaluated at different operating conditions.
Multi-Constrained Optimization of Running Characteristics of Mechanisms Lubricated With Compressible Fluid
Authors: Jai M. , Buscaglia G. , Iordanoff I.
Published: January 2004

The optimal design of gas-lubricated contacts is addressed, with emphasis on appropriate strategies for the management of constraints that usually arise from physical or manufacturing considerations. The necessary tools for evaluating the objective function (which is the load capacity in this case) and its gradient are recalled. The presentation aims at “black-box” implementations in which an optimization package is coupled with a completely independent Reynolds-equation solver. In our implementation DONLP2 is used as optimizer, while the solver is a Galerkin finite-element code. Two applications are reported: A fixed-volume planar slider bearing and a three-pad compliant journal bearing. In both cases the robustness of the approach is demonstrated and interesting aspects of the optimal gap profiles are presented.
A Computer Thermal Model of Mixed Lubrication in Point Contacts
Authors: Wang Wen-Zhong , Liu Yu-Chuan , Wang Hui , Hu Yuan-Zhong
Published: January 2004

This paper presents a transient thermal model for mixed lubrication problems in point contacts. The model deterministically calculates pressure and surface temperature by simultaneously solving a system of equations that govern the lubrication, contact and thermal behaviors of a point contact interface. The pressure distribution on the entire computation domain is obtained through solving a unified Reynolds equation system without identifying hydrodynamic or asperity contact regions. The point heat source integration method is applied to determine the temperature distributions on contact surfaces. The interactions between pressure and temperature are considered through incorporating viscosity-temperature and density-temperature relations in the Reynolds equation, then solving the equation system iteratively. With the successful implementation of an FFT-based algorithm (DC-FFT) for calculation of surface deformation and temperature rise, the numerical analysis of lubricated contact problems, which used to involve a great deal of computation, can be performed in acceptable time. The model enables us to simulate various lubrication conditions, from full film elastohydrodynamic lubrication (EHL) to boundary lubrication, for a better understanding of the effect of surface roughness. Numerical examples are analyzed and the results show that the present model can be used to predict pressure and surface temperature over a wide range of lubrication conditions, and that the solution methods are computationally efficient and robust.
On the Growth Rate of Thermoelastic Instability
Authors: Jang J. Y. , Khonsari M. M.
Published: January 2004

Thermoelastic instability (TEI) is known to be directly related to the occurrence of hot spots in friction systems, such as brakes, seals, and clutches. TEI is a failure process where the local frictional heat, thermal expansion, contacting pressure and temperature grow rapidly over a certain critical value of the operating speed. In this article, we examine the rate of growth of instability and establish a link between the wave speed and the configuration of hot spots as well as its penetrating depth. The analysis includes provision for surface roughness and is capable of treating bodies of finite thickness with or without liquid lubrication.
Traction Between a Web and a Smooth Roller
Authors: Mu¨ftu¨ Sinan , Jagodnik John J.
Published: January 2004

Web traction over rollers is known to deteriorate due to air entrainment at high web speeds. In this paper, a general model is presented to predict the traction capability of an impermeable web over a smooth roller. The model considers the effects of the web and roller speeds, roller radius, combined roughness of the two surfaces, web tension and thickness, friction coefficient, and compressible air bearing. The change of tension ΔN due to mechanical slip between the roller and the web is calculated by a simultaneous solution of the in-plane and out-of-plane equilibrium of the web and the compressible Reynolds lubrication equation. The problem is nondimensionalized and the effects of nine of the eleven nondimensional parameters on traction are investigated for a range of values. Formulas involving the nondimensional parameters for the traction capability are presented in two-variable polynomial forms.
Compensation of Cross-Coupling Stiffness and Increase of Direct Damping in Multirecess Journal Bearings Using Active Hybrid Lubrication: Part I—Theory
Authors: Santos Ilmar Ferreira , Watanabe Fla´vio Yukio
Published: January 2004

Fluid film forces are generated in hydrostatic journal bearings by two types of lubrication mechanisms: the hydrostatic lubrication in the bearing recesses and hydrodynamic lubrication in the bearing lands, when operating in rotation. The combination of both lubrication mechanisms leads to hybrid journal bearings (HJB). When part of hydrostatic pressure is also dynamically modified by means of hydraulic control systems, one refers to the active lubrication. The main contribution of the present theoretical work is to show that it is possible to reduce cross-coupling stiffness and increase the direct damping coefficients by means of the active lubrication, what leads to rotor-bearing systems with larger threshold of stability.
New Designs of HDD Air-Lubricated Sliders Via Topology Optimization
Authors: Lu Chung-Jen , Wang Tai-Kuo
Published: January 2004

Optimization is an efficient tool for developing designs of slider air bearings that meet the strict performance demands of current hard disk drives. Previous studies in this field concentrated on determining the optimal size and shape of the air-bearing surface for a specified initial design. The resulting optimal design has the same topology as that of the initial design. Therefore, the performance of the final optimal solution depends strongly on the initial design, which is chosen either intuitively or inspired by already existing designs. In this study, a topology optimization method is developed for determining the optimal slider configuration. First, the air-bearing surface is discretized by a uniform mesh. The optimization consists in determining whether the material contained in each element should be removed or not. Then, a genetic algorithm is employed for the determination of the optimal solution from the possible candidates. An example is presented to demonstrate the effectiveness of the proposed approach. The resulting optimal design has a topology different from those of the initial designs and possesses improved performance.
Mixed Lubrication Analyses by a Macro-Micro Approach and a Full-Scale Mixed EHL Model
Authors: Wang Q. Jane , Zhu Dong , Cheng Herbert S. , Yu Tonghui , Jiang Xiaofei , Liu Shuangbiao
Published: January 2004

This paper presents an improvement of a simplified approach, namely, the macro-micro approach, used to model the mixed elastohydrodynamic lubrication problems in counterformal contacts, and its comparison with Zhu and Hu’s full-scale mixed-EHL model. In this approach, Patir and Cheng’s average flow model is employed to obtain the distribution of piecewise average pressure. A contact-embedment method that incorporates the detail of asperity contact pressure into the overall pressure distribution is utilized to reveal the severity of surface interaction. Numerical experiments are conducted, and the results are compared with those obtained by means of the full-scale mixed-EHL. The regime of the application of this macro-micro approach is explored.
Optimal Clearance Configuration of Fluid-Film Journal Bearings for Stability Improvement
Authors: Matsuda Koichi , Kanemitsu Yoichi , Kijimoto Shinya
Published: January 2004

This paper aims to optimize a clearance configuration of fluid-film journal bearings. In order to improve stability of a rotating-machinery system, a performance index is given by summing the squared values of the attitude-angles over a region of eccentricity. A Fourier series is used to represent an arbitrary clearance configuration of a bearing, and the problem is to find the Fourier coefficients to minimize the performance index. The problem is numerically solved by a kind of the conjugate gradient method to yield a unique clearance configuration. The optimal clearance configuration is computed for various ratios of length to diameter of a bearing. A rigid-rotor system is used to verify that the designed bearing improves the system stability compared with that of a full circular bearing and to show that this optimization is more effective for shorter bearings.
Elasto-Plastic Normal Contact of Three-Dimensional Fractal Surfaces Using Halfspace Theory
Authors: Willner K.
Published: January 2004

The elasto-plastic normal contact of fractal surfaces is investigated. To study the influence of several surface parameters like fractal dimension and resolution, the surfaces are numerically generated using a special form of the structure function which is motivated by measurements of real rough surfaces. The contact simulation uses an iterative elastic halfspace solution based on a variational principle. A simple modification allows also the approximative solution of elasto-plastic contact problems. The influence of different surface parameters is studied with respect to the load-area relationship and the load-gap relationship. The simulations show that for realistic surface parameters the deformation is always in the plastic range.
Starved Lubrication of Elliptical EHD Contacts
Authors: Damiens B. , Venner C. H. , Cann P. M. E. , Lubrecht A. A.
Published: January 2004

This paper focuses on the lubrication behavior of starved elliptical Elasto-HydroDynamic (EHD) contacts. Starvation is governed by the amount of lubricant available in the inlet region and can result in much thinner films than occurring under fully flooded conditions. Therefore, it would be desirable to be able to predict the onset and severity of starvation and to be able to relate film reduction directly to the operating conditions and lubricant properties. The aim of this work is to explore the influence of these parameters on starvation. A combined modeling and experimental approach has been employed. The numerical model has been developed from an earlier circular contact study [1]. In this model, the amount and distribution of the lubricant in the inlet region determines the onset of starvation and predicts the film decay in the contact. Numerical simulations for a uniform layer on the surface show that a single parameter, characteristic of the inlet length of the contact in the fully flooded regime, determines the starved behavior. Film thickness measurements under starved conditions were performed to validate this theory. For a circular contact excellent agreement was found. In theory the same mechanism applies to elliptic contacts, however, the behavior is more complicated.
Granular Lubrication: Toward an Understanding of the Transition Between Kinetic and Quasi-Fluid Regime
Authors: Iordanoff I. , Khonsari M. M.
Published: January 2004

This paper is devoted to the understanding of flow characteristics of granular lubrication. The regimes of interest are: the kinetic regime in which collisions between particles are essentially binary and the quasi-fluid regime in which the duration of particle-to-particle contact is longer, primarily due to compaction. For this purpose, a quasi-two-dimensional particle dynamic simulation package is developed. The contact parameters between particles are chosen in order to mimic kinetic simulations. These contact laws are also valid in the quasi-fluid regime. The predictions of the particle dynamic simulations are compared to those obtained using the kinetic model. Good agreement between the two approaches is demonstrated. Furthermore, it is shown how the flow transition between the kinetic and the quasi-fluid regime can be determined. The influence of parameters that affect the transition is studied. The magnitude of the area fraction, on the order of about 90 percent of that of a hexagonal closest packing, seems to be the main factor that determines this transition.
Cdh1-APC Controls Axonal Growth and Patterning in the Mammalian Brain
Authors: Konishi Yoshiyuki , Stegmüller Judith , Matsuda Takahiko , Bonni Shirin , Bonni Azad
Published: January 2004

The anaphase-promoting complex (APC) is highly expressed in postmitotic neurons, but its function in the nervous system was previously unknown. We report that the inhibition of Cdh1-APC in primary neurons specifically enhanced axonal growth. Cdh1 knockdown in cerebellar slice overlay assays and in the developing rat cerebellum in vivo revealed cell-autonomous abnormalities in layer-specific growth of granule neuron axons and parallel fiber patterning. Cdh1 RNA interference in neurons was also found to override the inhibitory influence of myelin on axonal growth. Thus, Cdh1-APC appears to play a role in regulating axonal growth and patterning in the developing brain that may also limit the growth of injured axons in the adult brain.
Assignment ofNeisseria meningitidisSerogroups A, C, W135, and Y Anticapsular Total Immunoglobulin G (IgG), IgG1, and IgG2 Concentrations to Reference Sera
Authors: Joseph Helen , Balmer Paul , Bybel Mike , Papa Thomas , Ryall Robert , Borrow Ray
Published: January 2004

Meningococcal serogroup-specific immunoglobulin G (IgG), IgG1, and IgG2 concentrations were assigned to three reference sera, CDC 1992, 89-SF, and 96/562, for meningococcal serogroups A, C, Y, and W135 via the method of cross standardization. The sum of the serogroup-specific IgG1 and IgG2 concentrations determined for the four meningococcal serogroups showed good agreement with the serogroup-specific IgG either determined here or as previously represented. Following the assignment of meningococcal serogroup-specific IgG1 and IgG2 concentration to these reference sera, a meningococcal serogroup-specific IgG1 and IgG2 enzyme-linked immunosorbent assay protocol was developed. The serogroup A and C specific subclass distribution of a panel of adult sera collected following vaccination with any combination of meningococcal serogroup C conjugate, bivalent, or tetravalent polysaccharide vaccines was determined. For the determination of serogroup W135 and Y specific subclass distribution, an adolescent panel 28 days following a single dose of either tetravalent polysaccharide or conjugate vaccine was used. The sum of the serogroup-specific IgG1 and IgG2 showed strong correlation with the serogroup-specific total IgG determined. The assignment here of IgG1 and IgG2 subclasses to these reference sera will allow more detailed evaluation of meningococcal conjugate and polysaccharide vaccines.
Fecal Immunoglobulin A Antibodies in Dogs Infected or Vaccinated with Canine Coronavirus
Authors: Decaro Nicola , Pratelli Annamaria , Tinelli Antonella , Martella Vito , Camero Michele , Buonavoglia Domenico , Tempesta Maria , Caroli Anna Maria , Buonavoglia Canio
Published: January 2004

Fecal secretory immunoglobulin A (IgA) antibodies in dogs infected or vaccinated with canine coronavirus (CCV) were evaluated by an enzyme-linked immunosorbent assay. The study was carried out with 32 fecal samples collected just before inoculation and at 28 days postinoculation. Five groups were studied: naturally infected dogs, experimentally infected dogs, dogs inoculated with a modified live (ML) CCV vaccine by the intramuscular route, dogs inoculated with an ML CCV vaccine by the oronasal route, and dogs given an inactivated CCV vaccine. Both the naturally and the experimentally infected dogs developed high levels of fecal IgAs. Interestingly, dogs inoculated with the ML CCV vaccine by the oronasal route developed levels of fecal IgA that were higher than those observed in the dogs inoculated with the same CCV vaccine by the intramuscular route or those observed in dogs inoculated with the inactivated vaccine. A relationship between the level of fecal IgAs to CCV and the degree of protection against CCV infection was observed.
Gamma Interferon (IFN-γ) and IFN-γ-Inducing Cytokines Interleukin-12 (IL-12) and IL-18 Do Not Augment Infection-Stimulated Bone Resorption In Vivo
Authors: Sasaki Hajime , Balto Khaled , Kawashima Nobuyuki , Eastcott Jean , Hoshino Katsuaki , Akira Shizuo , Stashenko Philip
Published: January 2004

Periapical granulomas are induced by bacterial infection of the dental pulp and result in destruction of the surrounding alveolar bone. In previous studies we have reported that the bone resorption in this model is primarily mediated by macrophage-expressed interleukin-1 (IL-1). The expression and activity of IL-1 is in turn modulated by a network of Th1 and Th2 regulatory cytokines. In the present study, the functional roles of the Th1 cytokine gamma interferon (IFN-γ) and IFN-γ-inducing cytokines IL-12 and IL-18 were determined in a murine model of periapical bone destruction. IL-12−/−, IL-18−/−, and IFN-γ−/−mice were subjected to surgical pulp exposure and infection with a mixture of four endodontic pathogens, and bone destruction was determined by microcomputed tomography on day 21. The results indicated that all IL-12−/−, IL-18−/−, and IFN-γ−/−mice had similar infection-stimulated bone resorption in vivo as wild-type control mice. Mice infused with recombinant IL-12 also had resorption similar to controls. IFN-γ−/−mice exhibited significant elevations in IL-6, IL-10, IL-12, and tumor necrosis factor alpha in lesions compared to wild-type mice, but these modulations had no net effect on IL-1α levels. Recombinant IL-12, IL-18, and IFN-γ individually failed to consistently modulate macrophage IL-1α production in vitro. We conclude that, at least individually, endogenous IL-12, IL-18, and IFN-γ do not have a significant effect on the pathogenesis of infection-stimulated bone resorption in vivo, suggesting possible functional redundancy in proinflammatory pathways.
Antibody Reactivity to Omp31 fromBrucella melitensisin Human and Animal Infections by Smooth and Rough Brucellae
Authors: Cassataro Juliana , Pasquevich Karina , Bruno Laura , Wallach Jorge C. , Fossati Carlos A. , Baldi Pablo C.
Published: January 2004

Group 3 of outer membrane proteins (OMPs) ofBrucellaincludes Omp25 and Omp31, which share 34% identity. Omp25 is highly conserved inBrucellaspecies, and Omp31 is present in allBrucellaspecies, exceptBrucella abortus. Antibodies toBrucella melitensisOmp31 have been sought only in infected sheep, and Western blotting of sera from infected sheep did not reveal anti-Omp31 reactivity. We obtained recombinant purified Omp31 (B. melitensis) and tested its recognition by sera from humans and animals suffering from brucellosis by an indirect enzyme-linked immunosorbent assay (ELISA). Serum samples from 74 patients, 57 sheep, and 47 dogs were analyzed; brucellosis was confirmed by bacteriological isolation in all ovine and canine cases and 31 human cases of brucellosis. Thirty-five patients (47%) were positive for antibodies to Omp31, including seven cases ofBrucella suisinfection, two cases ofB. abortusinfection, and three cases ofB. melitensisinfection. Of 39 sheep naturally infected withB. melitensis(biovars 1 and 3), 23 (59%) were positive for antibodies to Omp31. Anti-Omp31 antibodies were also detected in 12 of 18 rams (67%) in whichBrucella oviswas isolated from semen. Antibodies to Omp31 were also found in 41 (87%) of the 47 dogs, including 13 with recent infection. These results suggest that an indirect ELISA using recombinant purified Omp31 fromB. melitensiswould be of limited value for the diagnosis of human and animal brucellosis. Nevertheless, the potential usefulness of this antigen in combination with other recombinant proteins fromBrucellashould not be dismissed.
High Prevalence of Seropositivity to a Major Allergen of
Anisakis simplex
, Ani s 1, in Dyspeptic Patients
Authors: Toro Carlos , Caballero María Luisa , Baquero Margarita , García-Samaniego Javier , Casado Isabel , Rubio Margarita , Moneo Ignacio
Published: January 2004

Finding evidence of anisakidosis requires invasive methods. We have developed a serological assay based on the detection of an immunoglobulin E (IgE) specifically directed against Ani s 1 protein, a major parasite allergen of
Anisakis simplex
, which has shown a high level of accuracy in the diagnosis of anisakidosis. We used this tool to determine the prevalence of anti-Ani s 1 IgE in dyspeptic patients and to investigate if its seropositivity could be related to epidemiological factors other than raw fish consumption. A total of 174 dyspeptic patients who submitted to upper digestive tract endoscopy were studied. Specific IgE against Ani s 1 was determined by immunoblotting. Quantitative information on smoking, alcohol consumption, and fish consumption as well as a history of gastric surgery was recorded. Twenty-four (13.8%) patients were seropositive for Ani s 1 protein. The seroprevalence of anti-Ani s 1 IgE increased with age in patients who were less than 62 years old (
P
= 0.047). Seropositivity to Ani s 1 was associated with the consumption of fish in vinegar (
P
< 0.001), raw fish (
P
= 0.001), and smoked fish (
P
= 0.007). There was no relationship between anti-Ani s 1 IgE seropositivity and the number of cigarettes smoked (
P
= 0.098) or alcohol intake (
P
= 0.179). Five patients had undergone previous gastric surgery, and three of those patients were seropositive for Ani s 1 (
P
= 0.019). In multivariate analysis, the consumption of fish in vinegar (
P
= 0.006), raw fish (
P
= 0.017), and smoked fish (
P
= 0.002) and a history of gastric surgery (
P
= 0.005) were independent factors associated with anti-Ani s 1 IgE detection. In conclusion, at present, anisakidosis might frequently be underdiagnosed, and it might have a clinical role in patients with upper dyspeptic symptoms. Uncooked-fish ingestion and previous gastric surgery were associated with seropositivity for Ani s 1 protein.
Identification of Primary and Secondary Measles Vaccine Failures by Measurement of Immunoglobulin G Avidity in Measles Cases during the 1997 São Paulo Epidemic
Authors: Pannuti Cláudio S. , Morello Ricardo José , de Moraes José Cássio , Curti Suely Pires , Afonso Ana Maria S. , Camargo Maria Cláudia Corrêa , de Souza Vanda A. U. F.
Published: January 2004

Despite almost universal use of measles vaccines in recent decades, epidemics of the disease continue to occur. Understanding the role of primary vaccine failure (failure to seroconvert after vaccination) and secondary vaccine failures (waning immunity after seroconversion) in measles epidemics is important for the evaluation of measles control programs in developing countries. After a measles epidemic in São Paulo, Brazil, 159 cases previously confirmed by detection of specific immunoglobulin M (IgM) antibodies were tested for IgG avidity, and a secondary immune response, defined by an IgG avidity index of at least 30%, was established in 30 of 159 (18.9%) patients. Among the 159 patients, 107 (67.3%) had not been vaccinated and 52 (32.7%) had received one or more doses of measles vaccine. Of the 107 unvaccinated patients, 104 (97.2%) showed a primary immune response, defined as an IgG avidity index of less than 30%. Among the 52 patients with documented vaccination, 25 (48.1%) showed a primary immune response and 27 (51.9%) showed a secondary immune response, thereby constituting a secondary vaccine failure. Primary vaccine failure was observed in 13 of 13 patients vaccinated prior to 1 year of age and in 43.5 and 12.5%, respectively, of patients receiving one or two doses after their first birthdays. These results provide evidence that measurement of IgG avidity can be used to distinguish between primary and secondary vaccine failures in vaccinated patients with measles; the method can also be a useful tool for the evaluation of measles control programs.
Magnitude of Serum and Intestinal Antibody Responses Induced by Sequential Replicating and Nonreplicating Rotavirus Vaccines in Gnotobiotic Pigs and Correlation with Protection
Authors: Azevedo Marli S. P. , Yuan Lijuan , Iosef Cristiana , Chang Kyeong-Ok , Kim Yunjeong , Van Nguyen Trang , Saif Linda J.
Published: January 2004

A sequential mucosal prime-boost vaccine regimen of oral attenuated (Att) human rotavirus (HRV) priming followed by intranasal (i.n.) boosting with rotavirus protein VP2 and VP6 rotavirus-like particles (2/6-VLPs) has previously been shown to be effective for induction of intestinal antibody-secreting cell (ASC) responses and protection in gnotobiotic pigs. Because serum or fecal antibody titers, but not intestinal ASC responses, can be used as potential markers of protective immunity in clinical vaccine trials, we determined the serum and intestinal antibody responses to this prime-boost rotavirus vaccine regimen and the correlations with protection. Gnotobiotic pigs were vaccinated with one of the two sequential vaccines: AttHRV orally preceding 2/6-VLP (VLP2x) vaccination (AttHRV/VLP2x) or following VLP2x vaccination (VLP2x/AttHRV) given i.n. with a mutant
Escherichia coli
heat-labile toxin (mLT) as adjuvant. These vaccines were also compared with three i.n. doses of VLP+mLT (VLP3x) and one and three oral doses of AttHRV (AttHRV1x and AttHRV3x, respectively). Before challenge all pigs in the AttHRV/VLP2x group seroconverted to positivity for serum immunoglobulin A (IgA) antibodies. The pigs in this group also had significantly higher (
P
< 0.05) intestinal IgA antibody titers pre- and postchallenge and IgG antibody titers postchallenge compared to those in the other groups. Statistical analyses of the correlations between serum IgM, IgA, IgG, and virus-neutralizing antibody titers and protection demonstrated that each of these was an indicator of protective immunity induced by the AttHRV3x and the AttHRV/VLP2x regimens. However, only IgA and not IgM or IgG antibody titers in serum were highly correlated (
R
2
= 0.89;
P
< 0.001) with the corresponding isotype antibody (IgA) titers in the intestines among all the vaccinated groups, indicating that the IgA antibody titer is probably the most reliable indicator of protection.
Maintenance of Serum Immunoglobulin G Antibodies to Epstein-Barr Virus (EBV) Nuclear Antigen 2 in Healthy Individuals from Different Age Groups in a Japanese Population with a High Childhood Incidence of Asymptomatic Primary EBV Infection
Authors: Harada Shizuko , Kamata Yoshio , Ishii Yasuyuki , Eda Hiroyuki , Kitamura Ryo , Obayashi Maya , Ito Sayuri , Ban Fumihiko , Kuranari Jun , Nakajima Haruhiko , Kuze Tomoko , Hayashi Masao , Okabe Nobuhiko , Senpuku Hidenobu , Miyasaka Nobuyuki , Nakamura Yoshiko , Kanegane Hirokazu , Yanagi Kazuo
Published: January 2004

Immunoglobulin G (IgG) antibodies to Epstein-Barr virus (EBV) nuclear antigens 2 and 1 (EBNA-2 and EBNA-1, respectively) were studied using sera from healthy individuals of a population with a high incidence of asymptomatic primary EBV infections during infancy or childhood in Japan. Two CHO-K1 cell lines expressing EBNA-2 and EBNA-1 were used for anticomplement and indirect immunofluorescence assays. The positivity rate for EBNA-2 IgG rose in the 1- to 2-year age group, increased and remained at a plateau (∼45%) between 3 and 29 years of age (3- to 4-, 5- to 9-, 10- to 14-, and 15- to 29-year age groups), and then reached 98% by age 40 (≥40-year age group). Both seropositivity for EBNA-1 and seropositivity for EBNAs in Raji cells (EBNA/Raji) were detected in the 1- to 2-year age group, remained high, and finally reached 100% by age 40. The geometric mean titer (GMT) of EBNA-2 IgG reached a plateau in the 5- to 9- and 10- to 14-year-old groups and remained elevated in the older age groups (15 to 29 and ≥40 years). The GMT of EBNA-1 IgGs increased to a plateau in the 1- to 2-year-old group and remained unchanged in the older age groups. The GMT of EBNA/Raji IgGs also reached a plateau in the 1- to 2-year-old group, remained level throughout the 3- to 14-year age groups, and decreased in the 15- to 29-year-olds. EBNA-2 IgGs emerged earlier than EBNA-1 IgGs in 8 of 10 patients with infectious mononucleosis, who were between 1 and 27 years old, and declined with time in three of eight cases. These results suggest that EBNA-2 IgG antibodies evoked in young children by asymptomatic primary EBV infections remain elevated throughout life, probably because of reactivation of latent and/or exogenous EBV superinfection.
Simultaneous Detection and Differentiation of Anti-
Helicobacter pylori
Antibodies by Flow Microparticle Immunofluorescence Assay
Authors: Bühling F. , Koch G. , Wex T. , Heimburg A. , Vieth M. , Leodolter A. , Roessner A. , Ansorge S. , Malfertheiner P.
Published: January 2004

Helicobacter pylori
is the key pathogen for gastroduodenal diseases. The clinical outcome of
H. pylori
infection is influenced by the presence of strain-specific virulence factors that are usually detected by the presence of specific anti-
H. pylori
antibodies in serum. Apart from the detection of these antibodies by enzyme-linked immunosorbent assay (ELISA), it is desirable to obtain additional information concerning the presence of certain virulence factors of
H. pylori
that are currently detected by immunoblot analysis. At present, the immunodiagnosis of an
H. pylori
infection includes two separate methods: ELISA and immunoblot analysis. Here, we report the development and evaluation of a new rapid flow microparticle immunofluorescence assay (FMIA) for detection of anti-
H. pylori
antibodies in human serum. The assay allows rapid qualitative and quantitative detection of anti-
H. pylori
antibodies by using crude antigen preparations as well as single recombinant antigens (urease A, urease B, CagA, and alkylhydroxy peroxide reductase) in the same sample with one measurement, and thus it combines the advantages of enzyme immunoassay and Western blot analysis. Seventy-five patient samples were analyzed by FMIA, ELISA, and Western blotting with respect to their immunoreactivity against crude
H. pylori
extracts and individual
H. pylori
antigens. Statistical analyses revealed an overall similarity of more than 90% among the results for FMIA, ELISA, and Western blot. Therefore, we conclude that FMIA is a powerful and time- and cost-saving assay system for the detection of antimicrobial antibodies, with higher sensitivity and a larger measurement range than ELISA.
Specificity of the Antibody Response to the Pneumococcal Polysaccharide and Conjugate Vaccines in Human Immunodeficiency Virus-Infected Adults
Authors: Feikin Daniel R. , Elie Cheryl M. , Goetz Matthew B. , Lennox Jeffrey L. , Carlone George M. , Romero-Steiner Sandra , Holder Patricia F. , O'Brien William A. , Whitney Cynthia G. , Butler Jay C. , Breiman Robert F.
Published: January 2004

Nonspecific antibodies, which are thought to be nonprotective, have been shown to contribute a substantial proportion of the measured concentration in the standardized immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) for pneumococcal polysaccharide capsular antibodies. The presence of such antibodies in human immunodeficiency virus (HIV)-infected persons has not been evaluated. The amount of nonspecific antibodies is proportional to the reduction in IgG antibody concentration that occurs with serum absorption with the heterologous polysaccharide 22F. We measured the amount of nonspecific antibodies before and after vaccination with the pneumococcal conjugate vaccine (PCV;
n
= 33) or the pneumococcal polysaccharide vaccine (PPV;
n
= 34) in HIV-infected adults with CD4 counts of ≥200 cells/mm
3
. Blood was drawn before and 2 months after vaccination. For prevaccination sera, we found a substantial amount of nonspecific antibodies for serotypes 4, 6B, 9V, and 23F (23 to 47% of measured IgG concentration), but not for serotype 14. There tended to be proportionately less nonspecific antibodies in postvaccine sera than prevaccine sera for PCV, but not for PPV. Subjects with a low HIV viral load (≤400 copies/ml) had proportionately more nonspecific antibodies than those with higher viral load before and after both vaccines. After 22F absorption, the geometric mean concentrations of antibodies were significantly higher post-PCV than post-PPV for the high viral load group for all five serotypes, but for no serotypes in the low viral load group. These findings confirm that absorption with a heterologous pneumococcal polysaccharide (e.g., 22F) is necessary to remove nonspecific antibodies in a standardized IgG ELISA for pneumococcal capsular antibodies in HIV-infected adults.
Evaluation of Inflammatory and Renal-Injury Markers in Women Treated with Antibiotics for Acute Pyelonephritis Caused byEscherichia coli
Authors: Horcajada Juan P. , Velasco María , Filella Xavier , Alvarez Luisa , De Làzzari Elisa , Marín Jose Luis , Collvinent Blanca , Smithson Alex , Martínez Jose Antonio , Noguero Mariana , Vila Jordi , Mensa Josep
Published: January 2004

The evolution and the relationship between inflammatory and renal-injury markers in women with acute uncomplicated pyelonephritis under antimicrobial therapy were investigated in a prospective study. Markers were measured before and 6 and 24 h after the intravenous administration of 1 g of ceftriaxone. Before treatment, the median levels of all markers except the serum creatinine levels were high. Twenty-four hours after the onset of antibiotic treatment, the C-reactive protein (CRP) level continued to be high, while the serum interleukin-6 (IL-6) levels and the urine IL-6, IL-8, albumin, and immunoglobulin G (IgG) levels decreased significantly. In contrast, serum creatinine and tumor necrosis factor alpha levels and urineN-acetyl-β-glucosaminidase, α1-microglobulin, and β2-microglobulin levels did not change over time. There was a significant correlation between IL-6 and IL-8 levels and urine albumin and IgG levels (urine albumin and IgG levels are glomerular and urinary tract-injury markers) as well as between serum CRP levels and the levels of the tubular-injury markers. In women with acute pyelonephritis, appropriate antibiotic treatment rapidly decreases serum IL-6 levels and urine IL-6 and IL-8 levels, which correlate well with urine albumin and IgG levels.
Expression of the Bovine Leukemia Virus Envelope Glycoprotein (gp51) by Recombinant Baculovirus and Its Use in an Enzyme-Linked Immunosorbent Assay
Authors: De Giuseppe Antonio , Feliziani Francesco , Rutili Domenico , De Mia Gian Mario
Published: January 2004

The gene encoding the major envelope glycoprotein (gp51) with its signal sequence, represented by an additional NH
2
-terminal 33-residue amino acid sequence of bovine leukemia virus (BLV), was inserted into a baculovirus transfer vector. A recombinant virus expressing a secreted gp51 protein in insect cells was isolated. The recombinant gp51 expressed was characterized by using an anti-BLV monoclonal antibody by both Western blotting analysis and enzyme-linked immunosorbent assay (ELISA). The secreted gp51 was used as an antigen, and an ELISA with recombinant gp51 (rgp51) was developed for the detection of BLV antibodies. This new procedure was compared with a previous ELISA method for the detection of BLV antibodies and an agar gel immunodiffusion test performed with an unpurified BLV antigen preparation. The comparative testing of field samples showed that the ELISA with rgp51 is more specific and also suitable for the testing of pooled sera.
Systemic and Mucosal Responses to Oral Administration of Excretory and Secretory Antigens fromGiardia intestinalis
Authors: Jiménez Juan Carlos , Fontaine Josette , Grzych Jean-Marie , Dei-Cas Eduardo , Capron Monique
Published: January 2004

Giardia, a flagellated protozoan that infects the upper small intestine of its vertebrate host, is the most common parasitic protist responsible for diarrhea worldwide. Molecules released by the parasite, particularly excretory and secretory antigens, seemed to be associated with pathogenesis as well as with the expression ofGiardiavirulence. In the present work, we examined the effect of oral administration ofGiardia intestinalisexcretory and secretory antigens on systemic and local antibody response as well as on mucosal injuries in BALB/c mice. Significant titers of serum-specific immunoglobulin G1 (IgG1) and specific IgG2a were observed. Systemic and mucosal specific IgA antibodies were also recorded. A transient production of serum-specific IgE antibody and high total IgE levels were also detected, suggesting the presence in excretory and secretory proteins of factors promoting a specific IgE response. The sera of excretory and secretory antigen-treated mice recognized proteins of 50 and 58 kDa as well as electrophoretic bands of 15, 63, and 72 kDa that could support a proteinase activity. The in vitro exposure ofG. intestinalistrophozoites to heat-inactivated sera from mice orally inoculated with excretory and secretory antigens induced a decrease of growth, revealing a complement-independent inhibitory activity of specific serum antibodies. Furthermore, histological evaluation performed on the small and large intestines revealed moderate to acute histological changes comparable to those observed in natural or experimentalGiardiainfection characterized by eosinophilic infiltration, hypercellularity, and enterocytic desquamation. The present results suggested thatGiardiaexcretory and secretory antigens stimulate a preferential Th2 response, which is probably involved in the intestinal alterations associated with giardiasis.