Monocytes and macrophages are critical effectors and regulators of inflammation and the innate immune response, the immediate arm of the immune system. Dendritic cells initiate and regulate the highly pathogen-specific adaptive immune responses and are central to the development of immunologic memory and tolerance. Recent in vivo experimental approaches in the mouse have unveiled new aspects of the developmental and lineage relationships among these cell populations. Despite this, the origin and differentiation cues for many tissue macrophages, monocytes, and dendritic cell subsets in mice, and the corresponding cell populations in humans, remain to be elucidated.

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Development of Monocytes, Macrophages, and Dendritic Cells

Analysis of Development Edited by Prof Benjamin H Willier, Prof Paul A Weiss and Prof Viktor Hamburger Pp xii + 735 (Philadelphia and London: W B Saunders Company, 1955) 105s

Mechanisms of Development

Influx of macrophages plays a crucial role in tissue repair. However, the precise function of macrophages during the healing response has remained a subject of debate due to their functional dichotomy as effectors of both tissue injury and repair. We tested the hypothesis that macrophages recruited during the diverse phases of skin repair after mechanical injury exert specific functions to restore tissue integrity. For this purpose, we developed a mouse model that allows conditional depletion of macrophages during the sequential stages of the repair response. Depletion of macrophages restricted to the early stage of the repair response (inflammatory phase) significantly reduced the formation of vascularized granulation tissue, impaired epithelialization, and resulted in minimized scar formation. In contrast, depletion of macrophages restricted to the consecutive mid-stage of the repair response (phase of tissue formation) resulted in severe hemorrhage in the wound tissue. Under these conditions, transition into the subsequent phase of tissue maturation and wound closure did not occur. Finally, macrophage depletion restricted to the late stage of repair (phase of tissue maturation) did not significantly impact the outcome of the repair response. These results demonstrate that macrophages exert distinct functions during the diverse phases of skin repair, which are crucial to control the natural sequence of repair events.

https://www.researchgate.net/profile/Rajeev_Ranjan44/publication/41532153_Differential_roles_of_macrophages_in_diverse_phases_of_skin_repair/links/545badb10cf2f1dbcbcaff64.pdf

Differential Roles of Macrophages in Diverse Phases of Skin Repair

Behaviour of activated carbons with different pore size distributions and surface oxygen groups for benzene and toluene adsorption at low concentrations

In recent years, significant advances have been made in the definition of regulatory pathways that control normal and abnormal cardiac valve development. Here, we review the cellular and molecular mechanisms underlying the early development of valve progenitors and establishment of normal valve structure and function. Regulatory hierarchies consisting of a variety of signaling pathways, transcription factors, and downstream structural genes are conserved during vertebrate valvulogenesis. Complex intersecting regulatory pathways are required for endocardial cushion formation, valve progenitor cell proliferation, valve cell lineage development, and establishment of extracellular matrix compartments in the stratified valve leaflets. There is increasing evidence that the regulatory mechanisms governing normal valve development also contribute to human valve pathology. In addition, congenital valve malformations are predominant among diseased valves replaced late in life. The understanding of valve developmental mechanisms has important implications in the diagnosis and management of congenital and adult valve disease.

Heart Valve Development: Regulatory networks in development and disease

Comprehensive understanding of tissues and organs development requires a detailed description of tissues specific developmental programs. In particular, Gene Regulatory Networks need to be analyzed at the tissue level, requiring organ specific transcriptional landscapes to be established. Here, we describe an efficient and stringent strategy for cell purification of differentiating cells from Drosophila embryos by flow cytometry. This, combined to mRNA amplification, can be used for transcriptomic analysis of small, tissue-specific cell populations. We present an application to the Drosophila cardiac system, whose cell population represents 0.5 to 1% of total cells within the whole embryo. Based on widely available fluorescent reporter transgenes, this method should be applicable to a number of tissues and organs.

Tissue-specific cell sorting from Drosophila embryos: application to gene expression analysis.

Dust explosions are recognised as very major industrial hazards. A meticulous attention should be engaged towards their analysis, prevention and control. A number of causes can trigger a dust explosion. Static electricity is one of the ignition sources. The current safety standards for determining electrostatic ignition hazards of dusts, such as electrical resistivity and charge decay time, are currently used in the process industries. Nevertheless, the standardisation of the proposed protocols suffers mainly from the looseness of a clearly definite description concerning the experimental conditions. The content of the paper is focused on the influences of the time, the voltage, the temperature, the relative humidity and the compaction of the dust on the two precedent parameters. The obtained results clearly show the necessity to improve the current standards. A proposition to complete the conditions of the normalised protocols is suggested.

Dust and electrostatic hazards, could we improve the current standards?

Several routes were investigated to design high performance membranes for the separation of tert-butyl ethers (octane enhancers) from alcohols by pervaporation. These routes aim at incorporating Lewis base groups into good film-forming polymers with different structures. The Lewis base groups showed a high affinity to alcohols in screening tests, thus imparting high pervaporation selectivity to the polymer materials. They led to several membranes able to extract pure ethanol out of the azeotropic mixture, but with very low permeation rates. Further modifications of the polymer structure allowed us to synthesize materials with greatly enhanced transfer rates and with acceptable selectivity for industrial applications. Structure–property relationships were derived from sorption and pervaporation data for a qualitative prediction of the effect of polymer structure on the flux and selectivity. For these solvent–polymer systems the diffusion phenomenon appears to further improve the pervaporation selectivity f...

Alcohol/Ether Separation by Pervaporation. High Performance Membrane Design*

Emerging nanomanufactured products are being incorporated in a variety of consumer products ranging from closer body contact products (i.e. cosmetics, sunscreens, toothpastes, pharmaceuticals, clothing) to more remote body-contact products (electronics, plastics, tires, automotive and aeronautical), hence posing potential health and environmental risks. The new field of nanosafety has emerged and needs to be explored now rather than after problems becomes so ubiquitous and difficult to treat that their trend become irreversible. Such endeavour necessitates a transdisciplinary approach. A commonly forgotten and/or misunderstood risk is that of explosion/detonation of nanopowders, due to their high specific active surface areas. Such risk is emphasized and illustrated with the present development of an appropriate risk analysis. For this particular risk, a review of characterization methods and their limitations with regard to nanopowders is presented and illustrated for a few organic and metallic nanopowders.

https://iopscience.iop.org/article/10.1088/1742-6596/170/1/012032/pdf

Explosion risks from nanomaterials

This work aims to study the influence of the dispersion conditions in a standard 20L sphere on the explosibility of a nanopowder. Even more than for micropowders, the dispersion conditions have a strong impact on the dust cloud homogeneity and its particle size distribution (PSD). Due to their high surface energy, nanoparticles are prone to agglomeration, but such structures can be broken during the dispersion process. Varying the dispersion procedure, the ignition delay time and even the nozzle type (rebound or symmetric) leads to modifications of the dust specific surface area, and thus of its reactivity. Tests were performed on aluminum and carbon black nanopowders. They were characterized before and during their dispersion in the sphere, notably using in situ laser PSD measurement. The initial turbulence level of the dust cloud was determined by particle image velocimetry. A lower shear stress is exerted on the agglomerates by using the symmetric nozzle, which causes less fragmentation and decreases the explosion severity. However, the results obtained with this nozzle are more reproducible than with the rebound nozzle. Because pre-ignition phenomenon was observed for aluminum nanopowders during their injection through the electrovalve, the dust dispersion by dust lifting was experimented. With regard to the standard procedure, the maximum rate of pressure rise decreased by approximately 30% whereas the maximum overpressure remains nearly unchanged. It means that the same amount of dust reacts in both kinds of experiments but that less fragmentation occurs, which is confirmed by PSD measurements. This work brings some questions about the interpretation of the explosivity results related to nanopowders and highlights the potential need to introduce recommendations in the current standards.

Laurent Perrin

Papers

Tissue-specific cell sorting from Drosophila embryos: application to gene expression analysis.

Dust and electrostatic hazards, could we improve the current standards?

Alcohol/Ether Separation by Pervaporation. High Performance Membrane Design*

Explosion risks from nanomaterials

Nanopowders explosion: Influence of the dispersion characteristics