1,819 research outputs found

    The Whalers of Honfleur in the Seventeenth Century

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    The Honfleur admiralty archives have a remarkable collection of reports made by captains returning from their voyages, among which have been found the accounts of 31 whalers and one other which did not return to Honfleur. These archives also contain some lists of crews, equipment, and provisions on board. We have at our disposal therefore a very interesting collection of documents about 32 French whalers between 1668 and 1688. ... The first part of this paper deals with the ships, their owners and crews; the second part describes the practice of whaling

    Changes in the Amphibian Antibody Repertoire are Correlated With Metamorphosis and not With Age or Size

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    Tadpole and adult Xenopus, manipulated to be of comparable size, exhibited stagespecific antibody expression. The production of adult-type higher-affinity anti-DNP antibodies proved to be independent of the age and size of the individual and is concomitant with the completion of metamorphosis. The appearance of new antibody specificities at such a time suggests that their expression occurs with the cell turnover and renewal during a period of morphological changes

    Expression of MHC Class II Antigens During Xenopus Development

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    Larval and adult forms of the amphibian Xenopus differ in their MHC class II .expression. In tadpoles, class II epitopes can be detected by monoclonal antibodies only on B cells, macrophages (whatever their location), spleen reticulum, thymus epithelium, and the pharyngobuccal cavity. In contrast, all adult T cells express class II on their surface. The transitions in class II expression occur at metamorphosis and are accompanied by other changes. The skin is invaded by class II positive dendritic cells, and the skin glands differentiate and also express class II. The gut, which expressed class II in discrete areas of the embryonic tissue, becomes invaded with B cells, and its epithelium also becomes class II positive

    Somatic Mutations During an Immune Response in Xenopus Tadpoles

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    The tadpole B-cell repertoire is less diverse than that of the adult frog; their antibodies are of lower affinity and are less heterogenous. In order to determine whether this difference is due to a lack of or a reduced rate of somatic hypermutation, we analyzed and compared cDNA sequences utilizing VH1 elements with germline counterparts in isogenic LG7 tadpoles during an immune response. Indeed, tadpole VH1 sequences contained somatic mutations. There were zeo to 5 mutations per sequence, all single base-point mutations, with the high ratio of GC to AT base-pair alterations similar to that observed in adult frogs

    Lymphoid Tumors of Xenopus laevis with Different Capacities for Growth in Larvae and Adults

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    Three new lymphoid tumors offering an assortment of variants in terms of MHC class I expressions, MHC class II expression, and Ig gene transcription have been discovered in the amphibian Xenopus. One was developed in an individual of the isogenic LG15 clone (LG15/0), one in a frog of the LG15/40 clone (derived from a small egg recombinant of LG15), and one (ff-2) in a male ff sib of the individual in which MAR1, the first lymphoid tumor in Xenopus was found 2 years ago. These tumors developed primarily as thymus outgrowths and were transplantable in histocompatible tadpoles but not in nonhistocompatible hosts. Whereas LG15/0 and LG15/40 tumor cells also grow in adult LG15 frogs, the ff-2 tumor, like the MAR1 cell line, is rejected by adult ff animals. Using flow cytometry with fluorescence-labeled antibodies and immunoprecipitation analysis, we could demonstrate that, like MAR1, these three new tumors express on their cell surface lymphopoietic markers recognized by mAbs FIF6 and RC47, as well as T-cell lineage markers recognized by mAbs AM22 (CD8-1ike) and X21.2, but not by immunologobulin (Ig) nor MHC class II molecules. Another lymphocyte-specific marker AM15 is expressed by 15/0 and 15/40 but not ff-2 tumor cells. The ff-2 tumor cell expresses MHC class molecule in association with β2-microglobulin on the surface, 15/40 cells contain cytoplasmic I α chain that is barely detected at the cell surface by fluocytometry, and 15/0 cells do not synthesize class I α chain at all. The three new tumors all produce large amounts of IgM mRNA of two different sizes but no Ig protein on the membrane nor in the cytoplasm. All tumor cell types synthesize large amount of Myc mRNA and MHC class I-like transcripts considered to be non classical

    Finite Element Modeling of Pneumatic Bending Actuators for Inflated-Beam Robots

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    Inflated-beam soft robots, such as tip-everting vine robots, can control curvature by contracting one beam side via pneumatic actuation. This work develops a general finite element modeling approach to characterize their bending. The model is validated across four pneumatic actuator types (series, compression, embedded, and fabric pneumatic artificial muscles), and can be extended to other designs. These actuators employ two bending mechanisms: geometry-based contraction and material-based contraction. The model accounts for intricate nonlinear effects of buckling and anisotropy. Experimental validation includes three working pressures (10, 20, and 30 kPa) for each actuator type. Geometry-based contraction yields significant deformation (92.1% accuracy) once the buckling pattern forms, reducing slightly to 80.7% accuracy at lower pressures due to stress singularities during buckling. Material-based contraction achieves smaller bending angles but remains at least 96.7% accurate. The open source models available at http://www.vinerobots.org support designing inflated-beam robots like tip-everting vine robots, contributing to waste reduction by optimizing designs based on material properties and stress distribution for effective bending and stress management

    Type I IFN-mediated regulation of IL-1 production in inflammatory disorders

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    Although contributing to inflammatory responses and to the development of certain autoimmune pathologies, type I interferons (IFNs) are used for the treatment of viral, malignant, and even inflammatory diseases. Interleukin-1 (IL-1) is a strongly pyrogenic cytokine and its importance in the development of several inflammatory diseases is clearly established. While the therapeutic use of IL-1 blocking agents is particularly successful in the treatment of innate-driven inflammatory disorders, IFN treatment has mostly been appreciated in the management of multiple sclerosis. Interestingly, type I IFNs exert multifaceted immunomodulatory effects, including the reduction of IL-1 production, an outcome that could contribute to its efficacy in the treatment of inflammatory diseases. In this review, we summarize the current knowledge on IL-1 and IFN effects in different inflammatory disorders, the influence of IFNs on IL-1 production, and discuss possible therapeutic avenues based on these observation
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