Optimization of Novel 2D Material Based SPR Biosensor Using Machine Learning

Biosensors are needed for today's health monitoring system for detecting different biomolecules. Graphene is a monolayer material that can be utilized to sense biomolecules and design biosensors. We have proposed a Graphene-Gold-Silver hybrid structure design based on Zinc Oxide which gives sensitive performance to detect hemoglobin biomolecules. The advanced biosensor designed based on this hybrid structure shows the highest sensitivity of 1000 nm/RIU which is far better concerning similar structure previously analyzed. The graphene-gold-silver hybrid structure is presented for its possible reflectance results and electric field results. The E-field results match well with the reflectance results given by the sensitive hybrid structure. The sensing biomolecules are presented above the structure where a combination of graphene-gold-silver hybrid structure improves the sensitivity to a great extent. The optimized parameters are obtained by applying variations in the physical parameters of the design. The machine learning algorithm employed for reflectance prediction shows a high prediction accuracy and can be utilized for simulation resource reduction. The proposed biosensor can be used in real-time hemoglobin monitoring.

Staphylococcus aureus strains exhibit heterogenous tolerance to direct cold atmospheric plasma therapy

The global clinical and socioeconomic impact of chronic wounds is substantial. The main difficulty that clinicians face during the treatment of chronic wounds is the risk of infection at the wound site. Infected wounds arise from an accumulation of microbial aggregates in the wound bed, leading to the formation of polymicrobial biofilms that can be largely resistant to antibiotic therapy. Therefore, it is essential for studies to identify novel therapeutics to alleviate biofilm infections. One innovative technique is the use of cold atmospheric plasma (CAP) which has been shown to possess promising antimicrobial and immunomodulatory properties. Here, different clinically relevant biofilm models will be treated with cold atmospheric plasma to assess its efficacy and killing effects. Biofilm viability was assessed using live dead qPCR, and morphological changes associated with CAP evaluated using scanning electron microscopy (SEM). Results indicated that CAP was effective against Candida albicans and Pseudomonas aeruginosa, both as mono-species biofilms and when grown in a triadic model system. CAP also significantly reduced viability in the nosocomial pathogen, Candida auris. Staphylococcus aureus Newman exhibited a level of tolerance to CAP therapy, both when grown alone or in the triadic model when grown alongside C. albicans and P. aeruginosa. However, this degree of tolerance exhibited by S. aureus was strain dependent. At a microscopic level, biofilm treatment led to subtle changes in morphology in the susceptible biofilms, with evidence of cellular deflation and shrinkage. Taken together, these results indicate a promising application of direct CAP therapy in combatting wound and skin-related biofilm infections, although biofilm composition may affect the treatment efficacy.

Naïve Bayes classifier assisted automated detection of cerebral microbleeds in susceptibility-weighted imaging brain images

Cerebral microbleeds (CMBs) in the brain are the essential indicators of critical brain disorders such as dementia and ischemic stroke. Generally, CMBs are detected manually by experts, which is an exhaustive task with limited productivity. Since CMBs have complex morphological nature, manual detection is prone to errors. This paper presents a machine learning-based automated CMB detection technique in the brain susceptibility-weighted imaging (SWI) scans based on statistical feature extraction and classification. The proposed method consists of three steps: (1) removal of the skull and extraction of the brain; (2) thresholding for the extraction of initial candidates; and (3) extracting features and applying classification models such as random forest and naïve Bayes classifiers for the detection of true positive CMBs. The proposed technique is validated on a dataset consisting of 20 subjects. The dataset is divided into training data that consist of 14 subjects with 104 microbleeds and testing data that consist of 6 subjects with 63 microbleeds. We were able to achieve 85.7% sensitivity using the random forest classifier with 4.2 false positives per CMB, and the naïve Bayes classifier achieved 90.5% sensitivity with 5.5 false positives per CMB. The proposed technique outperformed many state-of-the-art methods proposed in previous studies.

CANAttack: Assessing Vulnerabilities within Controller Area Network

Current vehicles include electronic features that provide ease and convenience to drivers. These electronic features or nodes rely on in-vehicle communication protocols to ensure functionality. One of the most-widely adopted in-vehicle protocols on the market today is the Controller Area Network, popularly referred to as the CAN bus. The CAN bus is utilized in various modern, sophisticated vehicles. However, as the sophistication levels of vehicles continue to increase, we now see a high rise in attacks against them. These attacks range from simple to more-complex variants, which could have detrimental effects when carried out successfully. Therefore, there is a need to carry out an assessment of the security vulnerabilities that could be exploited within the CAN bus. In this research, we conducted a security vulnerability analysis on the CAN bus protocol by proposing an attack scenario on a CAN bus simulation that exploits the arbitration feature extensively. This feature determines which message is sent via the bus in the event that two or more nodes attempt to send a message at the same time. It achieves this by prioritizing messages with lower identifiers. Our analysis revealed that an attacker can spoof a message ID to gain high priority, continuously injecting messages with the spoofed ID. As a result, this prevents the transmission of legitimate messages, impacting the vehicle's operations. We identified significant risks in the CAN protocol, including spoofing, injection, and Denial of Service. Furthermore, we examined the latency of the CAN-enabled system under attack, finding that the compromised node (the attacker's device) consistently achieved the lowest latency due to message arbitration. This demonstrates the potential for an attacker to take control of the bus, injecting messages without contention, thereby disrupting the normal operations of the vehicle, which could potentially compromise safety.

A THOROUGH STUDY AND META-ANALYSIS OF THE PROGNOSTIC RELEVANCE OF THE C-REACTIVE-ALBUMIN RATIO IN ACUTE PANCREATITIS

Although most cases of acute pancreatitis (AP) are minor, severe cases are associated with a substantial risk of death. Acute pancreatitis (AP) is a common illness. Therefore, it is critical to assess AP severity as soon as possible. This review aimed to ascertain the predictive significance of the CRP to albumin ratio in individuals with AP. We searched PubMed, Science Direct, and Cochrane Library electronic databases Until January 2023. Studies that reported the CRP/alb ratio at admission and its relationship to the severity or death of patients with AP were included. Using a random-effects model, we computed the pooled mean difference (MD) and 95% confidence interval (CI). The quality of the included studies was evaluated using the Newcastle-Ottawa scale. This meta-analysis combined data from six trials with a total of 2244 patients. Upon admission, the CRP/alb ratio was higher in patients with severe AP than in those with mild to moderate AP (pooled MD:3.59; 95% CI:2.51-4.68; p<0.00001). Additionally, non-survivor AP patients had a substantially higher CRP/alb ratio than survivor AP patients (pooled MD:2.12; 95% CI:0.43-3.8; p<0.01). Individuals with AP may benefit from a high CRP/ALB ratio as a preliminary indicator of poor prognosis.

Age-at-death assessed with Lamendin's original and population-specific models in a modern Brazilian osteological collection

BACKGROUND

Estimating the age at death is a common procedure in the fields of forensic human identification and anthropological/archaeological investigations. Root translucency and periodontosis are regressive parameters used to estimate the age of adults, more specifically in Lamendin's method - established in 1992 in a French population. This study aimed to test the applicability and validity of Lamendin's method in a Brazilian osteological collection.

METHODS

The sample consisted of 74 single-rooted teeth obtained from 50 skeletal remains (mean age: 53.20 ± 16.17 years) from Southeast Brazil. Lamendin's method was applied to enable a comparison between chronological (CA) and estimated ages (EA). A new population-specific equation was designed for the studied sample and the outcomes were compared with those obtained with Lamendin's original equation.

RESULTS

The original methods led to a general underestimation of 11.32 years (8.83 years in males and 15.91 years in females). The method had a better performance among individuals between 40 and 59 years (mean differences between CA and EA: 4.8 years). The population-specific equation led to a mean overestimation of -2.04 years in males, and a mean underestimation of 3.77 years in females. Underestimations were considerably higher in other age groups.

CONCLUSION

Despite the apparent improvements, both the original and the population-specific equations revealed coefficients of concordance that were constantly low between CA and EA. These outcomes suggest restrictions to the application of Lamendin's method in the forensic field, especially for human identification. The method, however, seems to be applicable for anthropological/archaeological applications.

A Numerical Study of the Dynamics of Vector-Born Viral Plant Disorders Using a Hybrid Artificial Neural Network Approach

Most plant viral infections are vector-borne. There is a latent period of disease inside the vector after obtaining the virus from the infected plant. Thus, after interacting with an infected vector, the plant demonstrates an incubation time before becoming diseased. This paper analyzes a mathematical model for persistent vector-borne viral plant disease dynamics. The backpropagated neural network based on the Levenberg-Marquardt algorithm (NN-BLMA) is used to study approximate solutions for fluctuations in natural plant mortality and vector mortality rates. A state-of-the-art numerical technique is utilized to generate reference data for obtaining surrogate solutions for multiple cases through NN-BLMA. Curve fitting, regression analysis, error histograms, and convergence analysis are used to assess accuracy of the calculated solutions. It is evident from our simulations that NN-BLMA is accurate and reliable.

On the Computational Study of a Fully Wetted Longitudinal Porous Heat Exchanger Using a Machine Learning Approach

The present study concerns the modeling of the thermal behavior of a porous longitudinal fin under fully wetted conditions with linear, quadratic, and exponential thermal conductivities surrounded by environments that are convective, conductive, and radiative. Porous fins are widely used in various engineering and everyday life applications. The Darcy model was used to formulate the governing non-linear singular differential equation for the heat transfer phenomenon in the fin. The universal approximation power of multilayer perceptron artificial neural networks (ANN) was applied to establish a model of approximate solutions for the singular non-linear boundary value problem. The optimization strategy of a sports-inspired meta-heuristic paradigm, the Tiki-Taka algorithm (TTA) with sequential quadratic programming (SQP), was utilized to determine the thermal performance and the effective use of fins for diverse values of physical parameters, such as parameter for the moist porous medium, dimensionless ambient temperature, radiation coefficient, power index, in-homogeneity index, convection coefficient, and dimensionless temperature. The results of the designed ANN-TTA-SQP algorithm were validated by comparison with state-of-the-art techniques, including the whale optimization algorithm (WOA), cuckoo search algorithm (CSA), grey wolf optimization (GWO) algorithm, particle swarm optimization (PSO) algorithm, and machine learning algorithms. The percentage of absolute errors and the mean square error in the solutions of the proposed technique were found to lie between 10-4 to 10-5 and 10-8 to 10-10, respectively. A comprehensive study of graphs, statistics of the solutions, and errors demonstrated that the proposed scheme's results were accurate, stable, and reliable. It was concluded that the pace at which heat is transferred from the surface of the fin to the surrounding environment increases in proportion to the degree to which the wet porosity parameter is increased. At the same time, inverse behavior was observed for increase in the power index. The results obtained may support the structural design of thermally effective cooling methods for various electronic consumer devices.

Experimental realization of an active non-reciprocal metamaterial using an eigen-structure assignment control strategy

This paper presents a class of active non-reciprocal metamaterials (ANMMs) in an attempt to control the flow of acoustic waves along a one-dimensional acoustic duct. The proposed method distinguishes itself from the available approaches where the non-reciprocities are generated either actively or passively by various sources of nonlinearities, circulators and gyroscopic/gyrator components, and/or spatiotemporal modulation. The proposed method relies in its operation on a controller that is designed by simultaneous allocation of both the eigenvalues and eigenvectors. In other words, the entire eigen-structure of the closed-loop system is assigned as deemed necessary. Conventionally, the placement of the eigenvalues has been employed to enhance both the damping and response of the system. However, in this study, the focus is placed on adjusting the eigenvectors in a way that enables the spatial control and redistribution of the wave propagation along the acoustic duct in order to produce any desirable non-reciprocal behavior. During this entire process, the system continues to behave in a linear fashion. The theory governing the operation of this proposed approach is introduced, and a comprehensive experimental validation effort is presented to demonstrate the basic features, non-reciprocal behavior, and control characteristics. Generalization of the presented strategies to two-dimensional acoustic systems is a natural extension of the present work.

Evaluation of tuberculosis diagnostic tools, with extending MODS assay use to second line susceptibility testing

Tuberculosis diagnosis and drug susceptibility testing (DST) are considered a priority for prompt initiation of effective therapy, increasing the chance of cure, decreasing the development of resistance, and reducing transmission.

AIM

Our objective was to evaluate currently applied diagnostic tools for tuberculosis including microscopic examination, GeneXpert, culture, and microscopic observation drug susceptibility (MODS) assay, investigating MODS assay usage for second line DST against culture based methods.

MATERIAL AND METHODS

In this study the 120 sputum samples collected from suspected cases were over one year duration from December 2018 to January 2020. The samples were subjected to ZN microscopic examination, GeneXpert, MODS assay, and culture for detection of mycobacteria. Moreover, resistance to 5 drugs: isoniazid, rifampicin, ofloxacin, levofloxacin, and amikacin were tested using MODS against the proportion method.

RESULTS

The sensitivity and specificity of the MODS assay were similar culture method with the advantage of obtaining the results in a median time of 10.7 days. Whereas the specificity of ZN and GeneXpert was high among untreated cases and decreased in subjects with a history of treatment. Monoresistance was the most common form of resistance detected among new cases followed by multidrug resistance, with a categorical agreement between the two methods above 90% for all tested drugs.

CONCLUSIONS

MODS assay is an attractive option once standardized for second line susceptibility testing and GeneXpert assay is of high sensitivity for rapid detection of MTB and RIF resistance especially in treatment naive cases.

Active synthesis of a gyroscopic-nonreciprocal acoustic metamaterial

A class of active nonreciprocal metamaterials is developed to control the flow and distribution of energy along periodic dynamical systems. Such a development constitutes a radical departure from the currently available approaches where the non-reciprocities are generated either by utilizing various physical sources of passive nonlinearities, gyroscopic circulators, spatiotemporal modulation, or active control of nonlinear systems. The proposed active Nonreciprocal Gyroscopic Meta-Material (NGMM) cell consists of a one-dimensional acoustic duct provided with linear dynamic control capabilities that virtually synthesize a gyroscopic control action that generates non-reciprocal characteristics of tunable magnitude and direction. The controller is designed in order to enable the spatial control and redistribution of the wave propagation energy flow along the acoustic duct. During this entire process, the system behaves in a linear fashion. Numerical examples are presented to demonstrate the basic features, non-reciprocal behavior, as well as the energy flow characteristics. The presented concept and controller design of the NGMM can be extended to various critical structures to achieve realistic acoustic diode configurations in a simple and programmable manner.

Finite element modeling of one-dimensional nonreciprocal acoustic metamaterial with anti-parallel diodes

A class of passive nonreciprocal acoustic metamaterials is developed to control the flow and distribution of acoustic energy in acoustic cavities and systems. Such development departs radically from present methods that favor the transmission direction by using hardwired arrangements of the hardware and hence, it cannot be reversed. The proposed nonreciprocal acoustic metamaterial (NAMM) cell consists of a cylindrical acoustic cavity with piezoelectric flexible boundaries that provide control in one-dimension. These boundaries are connected to an array of anti-parallel diodes to introduce simultaneous nonlinear damping and stiffness effects that break the reciprocity of energy flow through the NAMM cell. A finite element model of the NAMM cell is developed to investigate the nonreciprocal characteristics of the cell by optimizing the parameters that influence the nonlinear damping and stiffness effects introduced by the diodes. Numerical examples are presented to demonstrate the effectiveness of the proposed NAMM in tuning the directivity, flow, and distribution of acoustic energy propagating though the metamaterial.

Active nonreciprocal metamaterial using an eigen-structure assignment control strategy

A class of active nonreciprocal metamaterials (ANMMs) is developed to control the flow and distribution of energy along periodic dynamical systems. Such a development constitutes a radical departure from the currently available approaches where the non-reciprocities are generated either by utilizing various sources of passive nonlinearities, gyroscopic circulators, spatiotemporal modulation, or active control of nonlinear systems. The proposed ANMM cell consists of a one-dimensional acoustic duct provided with linear active control capabilities. The controller is designed by simultaneous assignment of both the eigenvalues and eigenvectors, i.e., the entire eigen-structure, of the closed-loop system. Conventionally, the placement of the eigenvalues has been considered to improve the damping and system's response. However, in this study, the emphasis is placed also on tailoring the eigenvectors in order to enable the spatial control and redistribution of the wave propagation energy flow along the acoustic duct in such a manner that it can introduce non-reciprocity as well as control its direction and reversal. During this entire process, the system remains behaving in a linear fashion. Numerical examples are presented to demonstrate the basic features and non-reciprocal behavior, as well as the energy flow characteristics.

Incremental Construction for Scalable Component-Based Systems

The availability of smart and intelligent sensors has changed the monitoring, control and maintenance of a conventional and advanced cyber-physical system used in public or private sectors of a society. For example, internet of things (IoT)-based health, agricultural and weather management systems. With the emergence of such sensors, along with the new ways to communicate or coordinate with them, we need to analyze and optimize the system construction processes. In this paper, to address the issue of scalability for bigger and complex systems based on sensors, we redefine an incremental construction process with an emphasis on behavior preservation and study the effectiveness of the use of software component models from the component-based development domain. In this paper, to deal with the issue of scalability, we investigate component-based development approaches with respect to our defined process and propose a taxonomy of component models with respect to component/system behavior. Moreover, based on the outcome of our analysis, we recommend the EX-MAN component model as the most suitable approach. We investigate incremental construction in the context of the three main categories of current component models, namely models where components are: (i) objects, (ii) architectural units and (iii) encapsulated components. Furthermore, to evaluate our defined process and selection of EX-MAN, we designed three examples of systems using our proposed process in EX-MAN component model.

Incremental Composition Process for the Construction of Component-Based Management Systems

Cyber-physical systems (CPS) are composed of software and hardware components. Many such systems (e.g., IoT based systems) are created by composing existing systems together. Some of these systems are of critical nature, e.g., emergency or disaster management systems. In general, component-based development (CBD) is a useful approach for constructing systems by composing pre-built and tested components. However, for critical systems, a development method must provide ways to verify the partial system at different stages of the construction process. In this paper, for system architectures, we propose two styles: rigid architecture and flexible architecture. A system architecture composed of independent components by coordinating exogenous connectors is in flexible architecture style category. For CBD of critical systems, we select EX-MAN from flexible architecture style category. Moreover, we define incremental composition mechanism for this model to construct critical systems from a set of system requirements. Incremental composition is defined to offer preservation of system behaviour and correctness of partial architecture at each incremental step. To evaluate our proposed approach, a case study of weather monitoring system (part of a disaster management) system was built using our EX-MAN tool.

Tacrolimus and Sirolimus Once Daily Monotherapy Regimen as a Safe and Effective Long-Term Maintenance Immunosuppressive Therapy in Pediatric Liver Transplantation

BACKGROUND

Long-term efficiency of attenuated immunosuppressive therapies is not well characterized in pediatric liver transplantation (LT).

OBJECTIVE

To assess the efficiency of tacrolimus once daily (TAC-OD) and sirolimus once daily (SLR-OD) immunosuppression in pediatric LT.

METHODS

We retrospectively evaluated 59 children who underwent LT in our center during 2002 to 2016. Those including children who underwent planned decrease in immunosuppressant dose (stable clinical conditions after 2 years of LT), and those who underwent unplanned decrease in immunosuppressant dose (because of complications such as post-transplant lymphoproliferative disorder [PTLD] and renal failure).

RESULTS

25 of 59 children underwent planned decrease in immunosuppressant dosage (mean±SD duration of 4.5±1.8, range: 3-11 years); 34 had unplanned decrease (mean±SD of 1.3±0.6, range: 0.5-2.6 years). 19 of 25 children with planned conversion received TAC-OD; 6 received SLR-OD (22 with 1 mg/day dose, and 3 with 1 mg every two days). Of 34 children with unplanned conversion, 27 received TAC-OD, 7 SLR-OD (25 children with 1 mg/day, 7 with 1 mg every two days, 1 with 0.5 mg/day TAC, and 1 with 0.5 mg TAC every two days). We found no adverse events including acute or chronic graft rejection, renal insufficiency, infections, PTLDs, or cardiovascular thrombotic events after initiation of the modified immunosuppression in none of the groups.

CONCLUSION

TAC-OD or SLR-OD monotherapies are safe and effective for long-term management of LT children with either stable clinical conditions or those with LT complications.

Modified Independent Modal Space Control Method for Active Control of Flexible Systems

A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It also incorporates optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation effort.

The MIMSC method relies on an important feature which is based on ‘time sharing’ of a small number of actuators, in the modal space, to control effectively a large number of modes.

Numerical examples are presented to illustrate the application of the method to generic flexible systems. The obtained results suggest the potential of the devised method in designing efficient active control systems for large flexible structures.

Buoyancy- and Gravity-Powered Underwater Robots

This paper presents a new concept for driving underwater robots that is based on the interaction between the natural forces of buoyancy and gravity present in the underwater environment.

Mathematical models are developed to simulate the static and dynamic characteristics of a single-link arm as in fltcenced by its design parameters and operating conditions. A computer-controlled prototype of the arm is designed, built, and tested to demonstrate the feasibility of the concept. The effect of varying the control gains, sample interval, and con trol law on the dynamic performance of the arm is presented for different payloads.

The obtained results suggest the potential of this type of robot in handling objects underwater with minimal external energy.

[Relation between structure and function, of the cerebral artery "carotid" in laboratory rat submitted to atherogenic diet]

OBJECTIVE OF THE STUDY

The aim of our investigation was the study of the pathophysiology of the carotid artery in cases of nutritional stress in male atheroresistant Wistar rats.

MATERIALS AND METHODS

Were administered daily by gavage to experimental rats a high fat diet consisting of peanut oil, cholesterol (3%) and sodium cholate (1%). Throughout this experiment, we conducted monitoring of some biochemical parameters and the morpho-histopathology of the carotid cerebral artery. The results obtained are compared to those of control rats in the same experimental conditions.

RESULTS

We found that this fat diet resulted in experimental rats disruption of biochemical tests and tissular and cellular alterations in carotid wall. Indeed, the biochemical examination shows a significant increase of the parameters studied. Morphological examination revealed thickening of the carotid wall and histopathological examination of this artery, highlights the installation of a vascular remodeling from thickening of the intima-media to the installation of a probable atherosclerosis accompanied by a possible hyalinization and a net fibrosis.

CONCLUSION

At the end of this study, although notes that our fat diet could cause a metabolic disorder that can cause multiple tissue and cell damage observed in cerebral artery "carotid" of atheroresistant rats.

Sarcosaprophagous Diptera assemblages in natural habitats in central Spain: spatial and seasonal changes in composition

The composition and spatial distribution of sarcosaprophagous Diptera assemblages were studied using carrion-baited traps along a bioclimatic gradient of natural habitats in central Spain throughout the different seasons during 1 year. Calliphoridae and Muscidae were the most abundant families, accounting for, respectively, 41.9% and 35.1% of all Diptera specimens collected. Other abundant families were Heleomyzidae (8.4%), Sarcophagidae (6.9%) and Piophilidae (5.1%). Fly assemblage compositions differed among bioclimatic levels, with Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) being the dominant species in mesomediterranean habitats, Muscina levida (Harris) (Diptera: Muscidae) the dominant species in supramediterranean habitats, and Prochyliza nigrimana (Meigen) (Diptera: Piophilidae) the dominant species in oromediterranean habitats. Differences in assemblage composition were also found among seasons. Thermophobic species such as Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) and some species of Heleomyzidae were well represented during autumn, winter and spring in the three bioclimatic levels sampled. By contrast, thermophilic species such as Ch. albiceps and Lucilia sericata (Meigen) (Diptera: Calliphoridae) and most Muscidae and Sarcophagidae species were more abundant during summer and in mesomediterranean habitats located at lower elevations. Knowledge of the preferences of some species for certain habitats may be of ecological and forensic value and may establish a starting point for further research.

Acoustic metamaterials with circular sector cavities and programmable densities

Considerable interest has been devoted to the development of various classes of acoustic metamaterials that can control the propagation of acoustical wave energy throughout fluid domains. However, all the currently exerted efforts are focused on studying passive metamaterials with fixed material properties. In this paper, the emphasis is placed on the development of a class of composite one-dimensional acoustic metamaterials with effective densities that are programmed to adapt to any prescribed pattern along the metamaterial. The proposed acoustic metamaterial is composed of a periodic arrangement of cell structures, in which each cell consists of a circular sector cavity bounded by actively controlled flexible panels to provide the capability for manipulating the overall effective dynamic density. The theoretical analysis of this class of multilayered composite active acoustic metamaterials (CAAMM) is presented and the theoretical predictions are determined for a cascading array of fluid cavities coupled to flexible piezoelectric active boundaries forming the metamaterial domain with programmable dynamic density. The stiffness of the piezoelectric boundaries is electrically manipulated to control the overall density of the individual cells utilizing the strong coupling with the fluid domain and using direct acoustic pressure feedback. The interaction between the neighboring cells of the composite metamaterial is modeled using a lumped-parameter approach. Numerical examples are presented to demonstrate the performance characteristics of the proposed CAAMM and its potential for generating prescribed spatial and spectral patterns of density variation.

New piophilid in town: the first Palaearctic record of Piophila megastigmata and its coexistence with Piophila casei in central Spain

The genus Piophila Fallén (Diptera: Piophilidae) is known from only two species: Piophila casei (L.) is a major pest, a cosmopolitan species and is commonly used as a forensic indicator, whereas Piophila megastigmata McAlpine has until now only been recorded in a natural environment in South Africa. The present work reports the first occurrence of P. megastigmata in the Palaearctic region from specimens collected by carrion-baited traps throughout different natural habitats of central Spain. Furthermore, the species was also collected with P. casei on corpses of domestic pigs used in a carrion succession study in a periurban habitat in central Spain. Both species occurred on carrion in different seasons, but P. megastigmata was more abundant than P. casei in autumn, arriving earlier at the carcasses and persisting for a longer period. The contrary pattern was observed in spring. The presence of P. megastigmata in different localities in central Spain and its coexistence with P. casei in a periurban habitat make it a potentially useful new tool for legal medicine in Europe; thus this species must be considered in forensic entomology studies.

Thrombin activatable fibrinolysis inhibitor (TAFI) is not associated with recurrent miscarriage

AIM(S)

The present study aimed to discover whether there is an association between thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels and recurrent miscarriage (RM). In particular, TAFI antigen levels of women with RM were compared with those of a control group of women with previous uncomplicated pregnancies.

METHOD(S)

Group 1 comprised 48 women with RM, defined as the occurrence of two or more fetal losses before 20 weeks of gestation. Group 2 (the control group) was made up of 40 women who had undergone at least two healthy pregnancies and had no history of miscarriage. Group 1 was then stratified in to two groups according to the number of pregnancy losses and group 1A (2 pregnancy losses) consisted of 22 women whereas group 1B (three or more pregnancy losses) consisted of 26 women.

RESULTS

No difference was observed with regard to serum TAFI antigen levels between groups 1 and 2. There was also no statistical difference in serum TAFI antigen levels between group 1A and group 1B.

CONCLUSION

The findings of the current study indicated that TAFI antigen levels are not associated with RM. Further multi-centric research with more subjects is needed to better evaluate the role of TAFI in RM.

The duplicitous effects of interleukin 4 on tumour immunity: how can the same cytokine improve or impair control of tumour growth?

Successful tumour immunity relies on innate and adaptive immune responses, with cytokines like interleukin 4 (IL-4) known to influence tumour clearance in both positive and negative ways. Here, we summarise some of the murine tumour models used over the past two decades to assess the impact of IL-4 on tumour immunity, with emphasis on the effects of IL-4 on the tumour-induced CD8 T-cell response. These data are compared with our own recent studies showing that IL-4 impairs CD8+ T-cell-mediated immunity against the mastocytoma cell line P815 expressing the immunogenic HLA-CW3 gene; moreover, we hypothesise that quantitative and qualitative differences in the HLA-CW3-induced CD8+ T-cell response impair control of tumour growth and aid the development of secondary tumours. We conclude that the duplicitous effects of IL-4 on tumour immunity depend on the type of effector cell (adaptive/innate) mediating tumour clearance and whether tumour growth depends on stromal infrastructure. Thus, the search for factors that improve or weaken the effectiveness of tumour-specific T cells has to be continued to improve modern approaches of immunotherapy against cancer.

A relevant enzyme in granulomatous reaction, active matrix metalloproteinase-9, found in bovine Echinococcus granulosus hydatid cyst wall and fluid

In addition to the ability of matrix metalloproteinases (MMP) to degrade components of the extracellular matrix and their involvement in pathology-related processes of tissue remodeling, they were recently reported to enhance inflammation by activation of proinflammatory cytokines, or their release from the cell surface. In the work reported here, proteolytic activity previously found for hydatid cysts was further characterized as MMP-9. Active host MMP-9 was found in walls and fluids of bovine hydatid cysts of Echinococcus granulosus in the environment of granulomatous reaction. Pooled walls and fluids of hydatid cysts obtained from infected cattle were processed. Strong proteolytic activity was detected by zymography. The proteolytic fraction was purified by anion exchange and gelatin-agarose affinity chromatography. Major proteinases of the purified fraction were subjected to mass spectrometry and their identities were further confirmed by Western blotting using commercial anti-human MMP-9 monoclonal antibodies. Two proteinases were characterized as latent and active forms of host MMP-9. Using the same antibody for immunoblot, activity was localized, in paraffin-embedded sections of the parasite and the local host environment, to epithelioid and giant multinucleated cells. It is proposed here that MMP-9 is secreted by specialized host cells of monocytic lineage (epithelioid/giant cells) as an effector, in an attempt to digest the persistent foreign body. In vivo activation of MMP-9 suggests its involvement in inflammatory reaction and in the chemotaxis of inflammatory cells to the cyst. However, E. granulosus can deal efficiently with MMP-9. Research is suggested into possible immune evasion mechanisms, including the secretion of an inhibitory molecule.

Hepatitis colestásica aguda tras la reintroducción de atorvastatina

Consumption of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA) inhibitors, known as statins, has been associated with elevated transaminase levels but rarely with acute hepatitis. Recently, several cases of acute hepatitis secondary to atorvastatin therapy have been published. We report the case of a 72-year-old man who developed acute cholestatic hepatitis after reinitiating treatment with atorvastatin at a higher dose than that previously prescribed. After treatment discontinuation, the patient made a full recovery, with normalization of clinical and laboratory findings.

Cystic echinococcosis: analysis of the serological profile related to the risk factors in individuals without ultrasound liver changes living in an endemic area of Tacuarembó, Uruguay

Cystic echinococcosis (CE) is a high prevalence zoonosis among the rural population of Tacuarembó (Uruguay). The correlation between serological data and the incidence of risk factors was studied in a survey carried out in 1998 among rural communities where 480 individuals were examined by means of abdominal sonography (local prevalence=0·8%). Serum samples (305) were analysed by ELISA to determine specific IgG against crude antigens from Echinococcus granulosus. A total of 27 individuals exhibiting no detectable changes in abdominal sonographic examination were found to be seropositive (‘ultrasound normal group’). Of these individuals 9 were seroreactive against purified antigen B. A significant degree of correlation was found between seroreactivity and the incidence of some risk factors (CE antecedent in the family, P<0·005 and use of rural water, P<0·0001) among this group. Follow-up of individuals of the ‘ultrasound normal group’ was carried out after 2 years to evaluate the implications of this serological reactivity. No predictive value for cyst development was assessed with complementary image study; in contrast transient antibodies were observed with both crude and purified antigen as approximately 60% of individuals became negative when re-sampled.

Isola spinal instrumentation system for idiopathic scoliosis

Since the definition of three-dimensional components of the scoliotic deformity, there have been important improvements in the surgical treatment of the problem. A derotation maneuver was proposed as a treatment option with CD instrumentation, but the reports of imbalance and decompensation with this system repopularized sublaminar wiring and translation as a corrective maneuver. Isola spinal instrumentation is one of the modern systems that utilizes vertebral translation instead of rod rotation. This study analyzes the results of 24 patients with idiopathic scoliosis who had been followed up for at least 2 years, and were surgically treated with titanium Isola Spinal Instrumentation in the Department of Orthopaedics and Traumatology, Ankara Social Security Hospital. Patients were grouped according to the King-Moe classification. Patients with type III, IV or V curves received only posterior instrumentation while this procedure followed anterior release and discectomy in the same session in patients with type I or II curves. A translation maneuver was utilized in the correction of scoliotic curves using the cantilever technique, either alone or supplemented by sublaminar wiring with Songer multifilament titanium cables. This study aimed to elucidate the effects of this technique in the frontal and sagittal plane curves and the trunk balance. The balance was analyzed clinically and radiologically by measurement of the lateral trunk shift (LT), shift of stable vertebra (SS), and shift of head (SH) in vertebral units (VU). The postoperative correction was significant in the frontal plane for all types of curves (p < 0.05). The postoperative correction was 80.9% +/- 9.5% in type III curves. Overall, the mean Cobb angle of the major curve value in the frontal plane was 66.9 degrees +/- 18.8 degrees, and it was corrected by 62.8% +/- 20.1%. The correction loss of Cobb angles in the frontal plane was 5.4 degrees +/- 5.5 degrees at the last follow-up visit. A normal physiologic thoracic contour (30 degrees - 50 degrees) was achieved in 83.3% of the patients and normal lumbar contour (40 degrees - 60 degrees) in 66.7% of the patients in the sagittal plane. The correction was found to be significant in all balance values (p < 0.05). The postoperative correction in LT values correlated with the correction of the Cobb angle values in the frontal plane. All patients had complete balance (SH: 0 VU and SS: 0 VU) or balanced curves (0 VU < SH, SS < 0.5 VU).Finally, the study concluded that the translation maneuver, especially when used with the cantilever technique, resulted in high correction rates in the frontal plane. Additionally, the technique was also successful in obtaining normal sagittal contours and correcting balance values.

Identification of circulating antigens, including an immunoglobulin binding protein, from Toxoplasma gondii tissue cyst and tachyzoites in murine toxoplasmosis

Here we describe the identification of Toxoplasma gondii circulating antigens in sera of BALB/c mice experimentally infected with either the virulent RH strain, or the cystogenic WTD1 strain or with an isolate from a human patient. The circulating antigens were identified by immunoblot in tachyzoite (RH strain) and in tissue cyst (ME-49 strain) crude antigens, using antibodies produced by immunisation of BALB/c mice with homologous sera from infected animals. The most relevant tachyzoite antigen identified are in the following four clusters of 109-94, 67-57, 35-31 and 28-21 kDa. Tissue cyst-specific circulating antigens, like the 18 kDa one, were detected in sera from mice infected with the cystogenic strains. These immune sera, after depletion of tachyzoite specific antibodies, recognised three tissue cysts antigens with Mr of 120, 79 and 48 kDa, and a cluster of antigens in the range of 68-53 kDa. We produced monoclonal antibodies by fusion of myeloma cells with lymphocytes from the mouse immunised with circulating antigens from the RH strain. One of the clones (3A11/H12) obtained, secretes IgG(1) and recognises a peptide epitope from a tachyzoite 67 kDa protein. This parasite protein also binds irrelevant mouse IgG(1) as well as immunoglobulins from other species. The reactivity with non-specific antibodies was inhibited by preincubation with 2% normal mouse and goat serum, while the reaction with the monoclonal antibody 3A11/H12 was not. Furthermore, a biotinylated F(ab')(2) of an irrelevant mouse IgG(1) did not show any reactivity while the F(ab')(2) of the monoclonal antibody 3A11/H12 reacts specifically with the 67 kDa antigen suggesting that this circulating antigen is a putative Fc binding protein.

Modulation of the cellular immune response by a carbohydrate rich fraction from Echinococcus granulosus protoscoleces in infected or immunized Balb/c mice

Infection of Balb/c mice with Echinococcus granulosus protoscoleces constitutes the model for secondary hydatid infection. The immune response of Balb/c mice infected with E. granulosus is characterized by secretion of antibodies specific for carbohydrate epitopes and production of type-2 cytokines. A role for glycoconjugates in the induction of type-2 responses has been suggested in other host--parasite systems. Although glycoconjugates are immunogenic in E. granulosus infection, the role of these molecules in the establishment of the type-2 response has never been analysed. In this study, a carbohydrate rich fraction (E4+) from E. granulosus protoscoleces was obtained using the monoclonal antibody E492/G1 specific for the moiety Galalpha(1,4)Gal which is widely represented in protoscoleces and other E. granulosus antigenic preparations. The results showed that E4+ was immunogenic in Balb/c mice evoking an antibody response mainly directed against carbohydrate epitopes. In addition, splenocytes from E4+-immunized mice showed suppressed proliferative responses to Con A and E4+ induced IL-10 secretion by E4+-primed and naive splenocytes. The fraction E4+ also was immunogenic in infected mice during early infection. In this case also, splenocytes from infected mice as well as peritoneal cells from infected or naive mice, when stimulated in vitro with E4+, secreted IL-10. Collectively, these results suggest that E4+ may be involved in immunosuppression phenomena and, by stimulating IL-10 secretion, may contribute to the induction and sustaining of the type-2 cytokine response established in early experimental infection.

Distribution of domestic Psocoptera in Madrid apartments

Domestic Psocoptera were sampled in Madrid throughout a complete year (1991-92) by means of sticky traps in bathrooms, kitchens and inside windows. A total of 409 individuals comprising ten species of psocids was caught from 4056 traps inspected fortnightly. The predominant species were Liposcelis decolor, Li. brunnea, Psyllipsocus ramburi, Li. bostrychophila, Li. pearmani, Dorypteryx domestica and Lachesilla pedicularia, in descending order of abundance. Apartments were classified according to eight quantitative variables: age and area of building, level of apartment (i.e. storey), numbers of windows, inhabitants, their pets (birds and mammals), ornamental plants indoors; and two qualitative factors: floor material and presence or absence of trees adjacent to the house. Psocid communities in human habitations were assessed by the island biogeography theory: diversity increased with apartment size and the number of species decreased with building date. Psocid populations were most abundant in bathrooms, which presumably act as sources for dispersal to other parts of the premises. No other significant correlations were found with the other housing factors investigated. Whereas psocids were active indoors during all months of the year, the peak prevalence was in summer, July and August, one or two months ahead of the local seasonal pattern for non-domestic psocids. Although psocids are usually not seriously unhygienic, causing only minor problems of contamination and allergies, this information should help towards their environmental control.

Characterization of MARCKS (Myristoylated alanine-rich C kinase substrate) identified by a monoclonal antibody generated against chick embryo neural retina

To identify molecular markers of cell differentiation in developing nervous tissue, monoclonal antibodies against chick embryo neural retina were made. One of them, 3C3mAb, recognized a developmentally regulated antigen present in several organs of the CNS. Data from MALDI-TOF mass spectrometry and peptide sequencing of the immuno-affinity purified protein indicated identity of the antigen with MARCKS. The immunoreactive material was always found as a unique polypeptide (Mr 71 kDa) in SDS-PAGE, however isoelectrofocusing revealed the existence of several bands (pI ranging from 4.0 to 4.5). Interestingly some retinal cell types, as photoreceptors, exhibited an extremely significant decrease in the intensity of the immunoreactive material during the final phases of terminal differentiation while others, as some retinal neurons, maintained the immunoreactivity when fully differentiated. Taken together these results indicate that MARCKS, a protein susceptible of several posttranslational modifications as myristoylation and phosphorylation at variable extent, may act differently in neural retina cell types.

Antibody response in CD4-depleted mice after immunization or during early infection with Echinococcus granulosus

The aims of this work were to investigate the existence of T-independent antigens in Echinococcus granulosus protoscoleces and to evaluate the relative contribution of T-independent stimulation to the overall antibody response in early infection. Mice depleted of CD4(+)-cells were immunized with protoscolex somatic antigens (PSA) or infected with E. granulosus protoscoleces (PSC). Results showed that the response of CD4-depleted immunized mice had the expected characteristics of a T-independent stimulation and that such T-independent stimulation was important mainly during primary response. During infection absence of CD4(+)-cells affected mainly the secretion of all IgG subclasses with the exception of IgG3 and IgM. To carry out a preliminary isolation of PSC T-independent antigens we prepared a carbohydrate enriched fraction from protoscolex antigens, using a monoclonal antibody specific for the carbohydrate moiety Gal alpha(1,4)Gal highly expressed in PSC. This fraction was mitogenic for naive mouse splenocytes and was recognized by a high percentage of the specific antibodies secreted by CD4-depleted immunized or infected mice. In summary, these results suggest that E. granulosus protoscoleces contain immunogenic T-independent antigens. Primary antibody responses to protoscolex somatic antigens and the production of IgM and IgG3 in early infection would be mainly stimulated by a T-independent mechanism.

Antibody and Th1/Th2-type responses in BALB/c mice inoculated with live or dead Echinococcus granulosus protoscoleces

The aims of this study were to investigate whether a Th1- or a Th2-type response is stimulated in the first stages of experimental infection with Echinococcus granulosus, and to determine whether live or dead protoscoleces equally contribute to such Th1/Th2-type polarization. Live parasites stimulated the production of IL-10, IL-4 and IL-5 as early as week 1 postinoculation. The levels of IL-10 and IL-4 decreased towards week 4 p.i. and that of IFN gamma increased. The production of specific antibodies was characterized by high levels of systemic IgG1 and local IgM and IgG3 (measured in peritoneal lavages). In contrast, dead parasites induced elevated levels of IL-4, IFN gamma, IL-10 and IL-5 on week 1 postinoculation followed by a decrease of IFN gamma and an increase of IL-4. Low levels of specific antibodies were stimulated by dead parasites both systemically and in the peritoneal cavity. These results show that E. granulosus infection induced an early Th2-type response and that live parasites stimulated stronger antibody responses than dead parasites. In addition, they strongly suggest that both phenomena were modulated by live protoscoleces.

Fc-binding molecules specific for human IgG1 and IgG3 are present in Echinococcus granulosus protoscoleces

In this work we describe the presence of Fc-binding activity on the suckers and tegument of E. granulosus protoscoleces. A fraction (PSA-Fc+) from protoscolex somatic antigens was isolated by affinity chromatography on human Fc-gamma1-Sepharose. Analysis by SDS-PAGE of PSA-Fc+ showed that it contained two major components. Using mouse F(ab')2-human Fc chimaeric monoclonal antibodies we verified that PSA-Fc+ bound mainly to human Fc-gamma1 and Fc-gamma3 isotypes. In addition, one of the components of PSA-Fc+ showed proteolytic activity. Both, Fc-binding and proteolytic activities localized on the protoscolex surface, may play a relevant role in the host-parasite interaction.

Subcellular distribution and profiles of prosomes (proteasomes-MCP) during differentiation of human lymphoblastic cell line

The human lymphoblastoid leukemic cell line (CCRF-CEM) was induced to differentiate with phorbol 12-myristate 13-acetate (PMA). During differentiation, assessed by monitoring the cluster of differentiation (CD) profile, the prosome (proteasomes, multi-catalytic proteinase) distribution and composition were studied by microscopy, flow cytometry and Western blot analysis. Changes in prosome subunits were monitored using 3 monoclonal antibodies anti-p23K, p29K and p31K. There were changes in the subcellular distribution of prosome antigens in PMA treated cells compared to untreated cells. The amount of cytoplasmic prosomal antigens decreased during the first three days of differentiation and the membrane antigens increased; meanwhile there was an increase of p53 and no change in actin protein levels. As mitotic cyclins are degraded by the ubiquitin pathway and therefore via the prosome, the decrease observed in differentiated cells suggests that prosomes are involved in the cell cycle and thus in cell proliferation.

Changes in the subunit distribution of prosomes (MCP-proteasomes) during the differentiation of human leukemic cells

The subunit composition of cell-internal and surface prosomes during phorbol myristate acetate (PMA)-induced differentiation of human leukemic T lymphocytes (CCRF-CEM cell line) was studied in relation to clusters of differentiation (CD) markers. PMA inhibited cell growth and decreased the amounts of CD1a and CD4 while CD3, CD8, CD25, CD45, CD57 and MHCI increased it; the p53 anti-oncogene increased while actin levels remained constant. Cells incubated with the inducer PMA for 3 days and placed in fresh inhibitor-free medium resumed growth at a low rate, while the CD values slowly reverted to those of the initial phenotype. The presence and relative amounts of prosome subunits were analyzed by flow cytometry, light and fluorescent microscopy and Western blotting using 3 monoclonal antibodies (p25K, p27K and p30-33K MAbs). The decrease in cytoplasmic antigens on day 3 was remarkable (cells followed for 7 days) while increased surface antigens were observed. Changes in the subcellular distributions of prosome antigens, particularly the p25K and p30-33K subunit, were correlated with a partial arrest of the cell cycle. Interestingly, the composition of cell internal and surface prosomes showed different patterns of change.

Prosomes (proteasomes) changes during differentiation are related to the type of inducer

The core of the 26S proteasome, the 20S prosome, is a highly organized multi-protein complex found in large amount in malignant cells. Differentiation of several cell lines, including the monoblastic U937 and the lymphoblastoid CCRF-CEM, is accompanied by a general decrease in the prosome concentration when phorbol-myrirtic-acetate (PMA) and retinoic acid plus dihydroxyvitamine D3 (RA+VD) are used. Incubation of U937 cells for three days with PMA or RA+VD causes differentiation, but the resulting patterns of prosome labeling in the cell and on the plasma membrane are not the same. In contrast, the same kind of prosome changes occur in U937 and CCRF-CEM cells when PMA is used as inducer. The intracellular distribution of prosomes is also linked to malignancy and differentiation. Prosomes are found in the nucleus and the cytoplasm of cancer cells; and treatment with RA+VD decreases the prosomes in the nucleus whereas PMA causes various prosome proteins changes. These results indicate that prosomes are important in cell regulation and in the expression of malignancy.

Carbohydrates on the surface of Echinococcus granulosus protoscoleces are immunodominant in mice

A carbohydrate enriched soluble fraction (CHP) was prepared by mild treatment of viable Echinococcus granulosus protoscoleces (PSC) with the enzyme endoglycosidase-F (endo-F) and characterized by SDS-PAGE, glycoside- inhibition ELISA, and immunoblotting. Three groups of four BALB/c mice were immunized with the CHP, with the remaining deglycosylated PSC (DGP) and with dead PSC (DPSC) to analyse the relative immunogenicity of carbohydrates on the surface of PSC. A fourth sentinel group was not immunized. The antibody response was analyzed during primary and hyperimmune responses. Specific antibody titres (IgG and IgM) against somatic PSC antigens (PSA) were evaluated by ELISA and their antigen recognition pattern by immunoblotting, discriminating carbohydrate and peptide specific antibody responses by periodate treatment of PSA. The avidity index of those antibodies and the titer of non-specific immunoglobulins during the whole protocol were evaluated by ELISA in vitro mitogenic activity of CHP was also evaluated. The results indicated: 1) immunodominance of surface carbohydrate epitopes from PSC, 2) predominant IgM and low avidity response against these epitopes, 3) a dramatic increase of non-specific antibody titres and 4) in vitro mitogenic activity of CHP.

Changes in the amount and distribution of prosomal subunits during the differentiation of U937 myeloid cells: high expression of p23K

Prosomes (Proteasomes/Multicatalytic proteinase (MCP)-complexes) are protein particles built of 28 subunits in variable composition, having proteinase activity. We have studied the changes in prosomal subunits p29K, p31K and the highly expressed p23K during the differentiation of U937 cells. Control cells had little prosomal subunit p31K in the cytoplasm, while p29K antigen was detected in both the nucleus and cytoplasm; more p23K antigen was found in the cytoplasm than in the nucleus. Flow cytometry demonstrated a biphasic intracellular decrease in prosomes during differentiation induced by phorbol-myristic-acetate (PMA) and retinoic acid plus 1,25-dihydroxycholecalciferol (RA + VD). p23K and p29K decreased both in the cytoplasm and the nucleus of differentiated cells, though the p23K antigen was concentrated near vesicles and the plasma membrane in PMA-induced cells. The p31K antigens disappeared from RA + VD-induced cells, while in PMA-induced cells, cytoplasmic labelling was unchanged and nuclear labelling was increased. Small amounts of prosomal proteins p23K and p29K were found on the outer membrane of un-induced cells. While there was no labelling on the outer membrane of RA + VD-induced cells, p23K protein increased on the plasma membrane of PMA-induced cells. The prosome-like particle protein p21K was not present to any significant extent in the intracellular compartment of control or induced cells; however, p21K was detected on the outer surface of control cells and was increased only in PMA-induced cells. The culture medium of control and induced cells contained no p21K, p23K, p29K or p31K. RA + VD seemed to induce a general decrease of prosomal subunits within the cells and at the outer surface, whereas PMA caused a migration toward the plasma membrane and an increase at the outer surface. These changes in the distribution and type of prosomes in RA + VD- and PMA-induced cells indicate that prosomes may play a part in differentiation, especially p23K which is the most highly expressed protein among those studied and presents the more important changes.

The perinatal presence of antigen (p-azophenylarsonate) or anti-mu antibodies lead to the loss of the recurrent idiotype (CRIA) in A/J mice

The immune response of A/J mice against p-azophenylarsonate (Ars)-keyhole limpet hemocyanin (KLH) is characterized by the dominance, late in primary and during the secondary, of a recurrent idiotype called CRIA, encoded by a canonical combination of Ig gene segments. In this study, A/J mice were given Ars coupled to deaggregated human gamma globulins (dHGG) within 24 h after delivery. The offsprings from these mice were then exposed as adults to Ars-KLH. These animals developed an unusual immune response. The level of anti-Ars antibodies was nearly normal but a dramatic shift in repertoire was observed: the cross-reactive idiotype which is the hallmark of the anti-Ars response in A/J mice was completely absent. The idiotype could be recovered by injection of anti-idiotypic antibodies alone, with no need of lipopolysaccharide coupling. Therefore the presence of antigen at birth can lead to a strong perturbation of idiotype selection. Similar results were obtained with neonatal treatment using anti-IgM antibodies. After recovery of suppression, A/J mice can mount an anti-arsonate response of normal level but devoid of the dominant idiotype.