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Claudio Lazzari - One of the best experts on this subject based on the ideXlab platform.
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Learning the way to blood: first evidence of dual olfactory Conditioning in a bloodsucking insect, Rhodnius prolixus. I. Appetitive learning
Journal of Experimental Biology, 2011Co-Authors: Clément Vinauger, Laura Buratti, Claudio LazzariAbstract:It has been largely assumed that the individual experience of insects that are disease vectors might not only contribute to animal fitness, but also have an important influence on parasite transmission. Nevertheless, despite the invested efforts in testing the capacity to learn and remember information in blood-sucking insects, only little conclusive information has been obtained to date. Adapting a classical Conditioning Approach to our haematophagous model, we trained larvae of Rhodnius prolixus to associate Llactic- acid, an odour perceived by these bugs but behaviourally neutral when presented alone, with food (i.e. positive reinforcement). Naive bugs - those exposed either to a conditioned stimulus (CS, L-lactic acid), unconditioned stimulus (US, heat) and reward (blood) alone or CS, US and reward in the absence of contingency - remained indifferent to the presence of an air stream loaded with L-lactic acid when tested in an olfactometer (random orientation), whereas the groups previously exposed to the contingency CS-US-reward (blood) were significantly attracted by L-lactic-acid. In a companion paper, the opposite, i.e. repellence, was induced in bugs exposed to the contingency of the same odour with a negative reinforcement. This constitutes the first evidence of olfactory Conditioning in triatomine bugs, vectors of Chagas disease, and one of the few substantiations available to date of olfactory Conditioning in haematophagous insects.
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Learning the way to blood: first evidence of dual olfactory Conditioning in a bloodsucking insect, Rhodnius prolixus. II. Aversive learning
Journal of Experimental Biology, 2011Co-Authors: Clément Vinauger, Laura Buratti, Claudio LazzariAbstract:After having demonstrated that blood-sucking bugs are able to associate a behaviourally neutral odour (L-lactic acid) with positive reinforcement (i.e. appetitive Conditioning) in the first part of this study, we tested whether these insects were also able to associate the same odour with a negative reinforcement (i.e. aversive Conditioning). Learned aversion to host odours has been repeatedly suggested as a determinant for the distribution of disease vectors among host populations. Nevertheless, no experimental evidence has been obtained so far. Adapting a classical Conditioning Approach to our haematophagous model, we trained larvae of Rhodnius prolixus to associate L-lactic acid, an odour perceived by bugs but behaviourally neutral when presented alone, with a mechanical perturbation (i.e. negative reinforcement). Naive bugs and bugs exposed to CS, punishment, or CS and punishment without contingency remained indifferent to the presence of an air stream loaded with L-lactic acid (random orientation on a locomotion compensator), whereas the groups previously exposed to the contingency CS-punishment were significantly repelled by L-lactic acid. In a companion paper, the opposite, i.e. attraction, was induced in bugs exposed to the contingency of the same odour with a positive reinforcement. These constitute the first pieces of evidence of olfactory Conditioning in triatomine bugs and the first demonstration that the same host odour can be used by insects that are disease vectors to learn to recognize either a host to feed on or a potentially defensive one. The orientation mechanism during repulsion is also discussed in light of our results.
Suzanne T. Ildstad - One of the best experts on this subject based on the ideXlab platform.
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A nonlethal Conditioning Approach to achieve engraftment of xenogeneic rat bone marrow in mice and to induce donor-specific tolerance.
Transplantation, 1998Co-Authors: Michael Neipp, Beate G. Exner, Suzanne T. IldstadAbstract:Background. The supply of solid organs for transplantation will never meet the growing demand. Xenotransplantation is considered to be a potential solution for the critical shortage of allografts. However, xenograft rejection is currently not controlled by conventional immunosuppressive agents. Bone marrow chimerism induces donor-specific tolerance without the requirement for chronic immunosuppressive therapy. The aim of this study was to develop a nonlethal recipient-Conditioning Approach to achieve mixed bone marrow chimerism and donor-specific tolerance. Methods. C57BL/10SnJ mice were conditioned with total body irradiation followed by a single injection of cyclophosphamide on day +2. On day 0, mice were reconstituted with untreated bone marrow cells from Fischer 344 rats. Recipients were analyzed by flow cytometry for donor bone marrow engraftment and multilineage chimerism. Donor-specific tolerance was tested by skin grafting. Results. One hundred percent of recipients engrafted after irradiation with 600 cGy total body irradiation, transplantation with 80×10 6 Fischer 344 bone marrow cells, and injection with 50 mg/kg cyclophosphamide intraperitoneally. Donor chimerism was detectable in all engrafted animals for up to 11 months. This Conditioning was nonlethal, because conditioned untransplanted animals survived indefinitely. Mixed xenogeneic chimeras were tolerant to donor-specific skin grafts but rejected third-party (Wistar Furth) grafts as rapidly as naive C57BL/10SnJ mice. In contrast, animals that received less efficacious Conditioning regimens and did not exhibit detectable chimerism showed prolonged graft survival, but delayed graft rejection occurred in all animals within 10 weeks. Conclusion. The induction of bone marrow chimerism and donor-specific tolerance after nonlethal Conditioning might be useful to prevent the vigorous cellular and humoral rejection response to xenografts.
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a nonlethal Conditioning Approach to achieve durable multilineage mixed chimerism and tolerance across major minor and hematopoietic histocompatibility barriers
Journal of Immunology, 1995Co-Authors: Yolonda L Colson, S S Boggs, P C Johnson, K D Patrene, Sherry M Wren, Matthew J Schuchert, Suzanne T. IldstadAbstract:Reconstitution of lethally irradiated mice with a mixture of syngeneic and allogeneic (A+B-->A) bone marrow results in multilineage mixed allogeneic chimerism, donor-specific transplantation tolerance, superior immunocompetence and resistance to graft-vs-host disease. However, the morbidity and mortality associated with lethal irradiation would be a major limitation to the clinical application of chimerism to induce tolerance for solid organ grafts or treat other nonmalignant hematologic diseases. We report here that durable multilineage mixed allogeneic chimerism and donor-specific transplantation tolerance for skin and primarily vascularized allografts can be achieved across multiple histocompatibility barriers using a nonmyeloablative radiation-based Approach. The percentage of B10 mouse recipients that engrafted directly correlated with the degree of disparity between donor and recipient and the dose of total body irradiation administered. Although the occurrence of engraftment following Conditioning with doses of total body irradiation of > or = 600 cGy was similar for animals receiving bone marrow disparate at MHC or MHC, minor and hematopoietic (Hh-1) loci (67% vs 78%), the level of donor chimerism was significantly less when multiple histocompatibility barriers were present (94.6 +/- 3.8% vs 37.5 +/- 12.5%). Treatment of the recipient with cyclophosphamide 2 days following allogeneic bone marrow transplantation reduced the dose of radiation sufficient for reliable engraftment to only 500 cGy of total body irradiation, regardless of MHC and Hh-1 disparity. Donor chimerism was stable and present in all lineages, with production of lymphoid (T and B cell), NK, and myeloid (erythrocyte, platelet, granulocyte, and macrophage) cells. Mixed chimeras exhibited donor-specific tolerance in vitro, as assessed by mixed lymphocyte culture (MLR) and cytotoxicity (CML) assays, and in vivo to skin and primarily vascularized cardiac allografts. The observation that engraftment and tolerance can be achieved across multiple histocompatibility barriers using nonmyeloablative recipient Conditioning may allow allogeneic bone marrow transplantation to be applied to nonmalignant disease states in which lethal Conditioning cannot be justified, including the induction of donor-specific tolerance for solid organ transplantation and the treatment of hemoglobinopathies and enzyme deficiency states.
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A minimal Conditioning Approach to achieve stable multilineage mouse plus rat chimerism.
Transplant immunology, 1995Co-Authors: A. Y. Abou El-ezz, S S Boggs, P C Johnson, K D Patrene, M.s. Itskowitz, Christina L. Kaufman, Suzanne T. IldstadAbstract:Abstract Transplantation of untreated rat bone marrow into lethally irradiated (950 cGy) mouse recipients results in durable xenogeneic (rat→mouse) chimerism and confers donor-specific transplantation tolerance for subsequent xenografts. The purpose of the present study was to characterize the minimal dose of total body irradiation (TBI) which would allow engraftment of rat bone marrow in mouse recipients. We report here that durable and stable lymphohaematopoietic cross-species chimerism can be achieved using a less than totally ablative radiation-based Conditioning Approach. The percentage of B10 mouse recipients which engrafted with rat bone marrow cells correlated with the dose of TBI. Engraftment of rat bone marrow stem cells occurred in all animals receiving 750 cGy prior to bone marrow transplantation, while no engraftment was detected at doses less than 650 cGy. Although most of the recipients were repopulated with mixed mouse and rat multilineage chimerism, some exhibited a predominance of rat cells. Although mixed xenogeneic rat/mouse chimeras prepared by lethal TBI produced only mouse derived RBC (red blood cells), chimeras prepared by sublethal Conditioning produced both rat and mouse RBC. Only animals with detectable chimerism exhibited specific functional transplantation tolerance to donor xenoantigens, as assessed in vitro by mixed lymphocyte reaction assay. This model may offer an in vivo Approach to study the role of species-specific growth factors in stem cell biology as well as the mechanisms for the induction of tolerance across species barriers.
P. Nouet - One of the best experts on this subject based on the ideXlab platform.
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Noise analysis of a first-order thermal ΣΔ architecture for convective accelerometers
Analog Integrated Circuits and Signal Processing, 2010Co-Authors: O. Leman, F. Mailly, L. Latorre, P. NouetAbstract:This paper presents the study of an original closed-loop Conditioning Approach for fully-integrated convective inertial sensors. The method is applied to an accelerometer manufactured on a standard CMOS technology using an auto-aligned bulk etching step. Using the thermal properties of the sensor, a first order sigma-delta modulator is built. This “electro-physical” modulator realizes an analog-to-digital conversion of the acceleration signal. Besides, the feedback mode of operation improves the sensor overall performance.
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Noise Analysis of a First-Order Thermal Sigma-Delta Architecture for Convective Accelerometers
Analog Integrated Circuits and Signal Processing, 2010Co-Authors: O. Leman, F. Mailly, L. Latorre, P. NouetAbstract:This paper presents the study of an original closed-loop Conditioning Approach for fully-integrated convective inertial sensors. The method is applied to an accelerometer manufactured on a standard CMOS technology using an auto-aligned bulk etching step. Using the thermal properties of the sensor, a first order sigma-delta modulator is built. This “electro-physical” modulator realizes an analog-to-digital conversion of the acceleration signal. Besides, the feedback mode of operation improves the sensor overall performance.
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STUDY OF FIRST-ORDER THERMAL SIGMA-DELTA ARCHITECTURE FOR CONVECTIVE ACCELEROMETERS
2008Co-Authors: P. Nouet, F. Mailly, L. LatorreAbstract:This paper presents the study of an original closed-loop Conditioning Approach for fully-integrated convective inertial sensors. The method is applied to an accelerometer manufactured on a standard CMOS technology using an auto-aligned bulk etching step. Using the thermal behavior of the sensor as a summing function, a first order sigma-delta modulator is built. This “electro-physical” modulator realizes an analog-to-digital conversion of the signal. Besides the feedback scheme should improve the sensor performance.
Clément Vinauger - One of the best experts on this subject based on the ideXlab platform.
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Learning the way to blood: first evidence of dual olfactory Conditioning in a bloodsucking insect, Rhodnius prolixus. I. Appetitive learning
Journal of Experimental Biology, 2011Co-Authors: Clément Vinauger, Laura Buratti, Claudio LazzariAbstract:It has been largely assumed that the individual experience of insects that are disease vectors might not only contribute to animal fitness, but also have an important influence on parasite transmission. Nevertheless, despite the invested efforts in testing the capacity to learn and remember information in blood-sucking insects, only little conclusive information has been obtained to date. Adapting a classical Conditioning Approach to our haematophagous model, we trained larvae of Rhodnius prolixus to associate Llactic- acid, an odour perceived by these bugs but behaviourally neutral when presented alone, with food (i.e. positive reinforcement). Naive bugs - those exposed either to a conditioned stimulus (CS, L-lactic acid), unconditioned stimulus (US, heat) and reward (blood) alone or CS, US and reward in the absence of contingency - remained indifferent to the presence of an air stream loaded with L-lactic acid when tested in an olfactometer (random orientation), whereas the groups previously exposed to the contingency CS-US-reward (blood) were significantly attracted by L-lactic-acid. In a companion paper, the opposite, i.e. repellence, was induced in bugs exposed to the contingency of the same odour with a negative reinforcement. This constitutes the first evidence of olfactory Conditioning in triatomine bugs, vectors of Chagas disease, and one of the few substantiations available to date of olfactory Conditioning in haematophagous insects.
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Learning the way to blood: first evidence of dual olfactory Conditioning in a bloodsucking insect, Rhodnius prolixus. II. Aversive learning
Journal of Experimental Biology, 2011Co-Authors: Clément Vinauger, Laura Buratti, Claudio LazzariAbstract:After having demonstrated that blood-sucking bugs are able to associate a behaviourally neutral odour (L-lactic acid) with positive reinforcement (i.e. appetitive Conditioning) in the first part of this study, we tested whether these insects were also able to associate the same odour with a negative reinforcement (i.e. aversive Conditioning). Learned aversion to host odours has been repeatedly suggested as a determinant for the distribution of disease vectors among host populations. Nevertheless, no experimental evidence has been obtained so far. Adapting a classical Conditioning Approach to our haematophagous model, we trained larvae of Rhodnius prolixus to associate L-lactic acid, an odour perceived by bugs but behaviourally neutral when presented alone, with a mechanical perturbation (i.e. negative reinforcement). Naive bugs and bugs exposed to CS, punishment, or CS and punishment without contingency remained indifferent to the presence of an air stream loaded with L-lactic acid (random orientation on a locomotion compensator), whereas the groups previously exposed to the contingency CS-punishment were significantly repelled by L-lactic acid. In a companion paper, the opposite, i.e. attraction, was induced in bugs exposed to the contingency of the same odour with a positive reinforcement. These constitute the first pieces of evidence of olfactory Conditioning in triatomine bugs and the first demonstration that the same host odour can be used by insects that are disease vectors to learn to recognize either a host to feed on or a potentially defensive one. The orientation mechanism during repulsion is also discussed in light of our results.
Frank P T Baaijens - One of the best experts on this subject based on the ideXlab platform.
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tissue engineering of human heart valve leaflets a novel bioreactor for a strain based Conditioning Approach
Annals of Biomedical Engineering, 2005Co-Authors: Anita Mol, Niels J B Driessen, Marcel C M Rutten, Simon P Hoerstrup, Carlijn V C Bouten, Frank P T BaaijensAbstract:Current mechanical Conditioning Approaches for heart valve tissue engineering concentrate on mimicking the opening and closing behavior of the leaflets, either or not in combination with tissue straining. This study describes a novel Approach by mimicking only the diastolic phase of the cardiac cycle, resulting in tissue straining. A novel, yet simplified, bioreactor system was developed for this purpose by applying a dynamic pressure difference over a closed tissue engineered valve, thereby inducing dynamic strains within the leaflets. Besides the use of dynamic strains, the developing leaflet tissues were exposed to pre-strain induced by the use of a stented geometry. To demonstrate the feasibility of this strain-based Conditioning Approach, human heart valve leaflets were engineered and their mechanical behavior evaluated. The actual dynamic strain magnitude in the leaflets over time was estimated using numerical analyses. Preliminary results showed superior tissue formation and non-linear tissue-like mechanical properties in the strained valves when compared to non-loaded tissue strips. In conclusion, the strain-based Conditioning Approach, using both pre-strain and dynamic strains, offers new possibilities for bioreactor design and optimization of tissue properties towards a tissue-engineered aortic human heart valve replacement.