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Basic Chemical Hazards to Human Health and Safety — II
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
The foremost nonspecific protective barrier is the skin, which prevents entry of invasive substances to the body within its limitations, which, though many, generally allow the skin to be an effective barrier anyway. Epithelial cells lining the respiratory, gastrointestinal, urinary, and reproductive tracts secrete mucus to engulf and trap foreign matter, and the hair-like cilia work to sweep the contaminated mucus to the nearest bodily exit. Phagocytes are cells that engulf and digest foreign matter and cellular debris. Macrophages, phagocytes that develop from monocytes, are found in the various tissues of the body. Neutrophils and eosinophils are phagocytes that develop from PMN leukocytes and remain in the bloodstream. Immobile macrophages, such as the Kupffer cells in the liver and the microglia in the central nervous system, maintain another defense barrier for their specific systems. Free macrophages circulate throughout the body as a general line of defense. Natural killer (NK) cells are lymphocytes that seek out and destroy abnormal cells, such as cancer cells or cells damaged by viral attack, by releasing proteins called perforins that penetrate cell walls.
Clinical Effects of Pollution
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
The phagocytic response of the innate immune system is crucial for the effective clearance of microbial pathogens and indispensable for host defense. This response is initiated following microbial pathogens and indispensable for host defense. This response is initiated following microbial contact with host phagocytes (mainly macrophages and neutrophils) and results in the engulfment and killing of microorganisms within phagosomes. Phagocytosis is associated with the production of ROS via the respiratory burst, a necessary effector response for the destruction of intracellular microorganisms.920,921 Although ROS are primarily produced by the NADPH oxidase system I phagocytes, mitochondrial oxidative metabolism is also a major source of cellular ROS. The production of mROS has traditionally been considered a deleterious consequence of electron transport, but mounting evidence indicates that mROS also facilitate antibacterial innate immune signaling and phagocyte bactericidal activity. Leukocytes and lymphocytes often are suppressed in the chemically sensitive with WBC running between 2000 and 5000, which tells that phagocytosis is impaired. These patients are not only prone to recurrent infections but also prone to all kinds of pollutant generated nonbiological inflammations.
Immunological Properties of Gold Nanoparticles
Published in Lev Dykman, Nikolai Khlebtsov, Gold Nanoparticles in Biomedical Applications, 2017
Phagocytic cells of the immune system have a multitude of various receptors on their surface, through which they bind and take up foreign material. Six types of phagocytosis receptors are differentiated: (1) mannose receptors (or C-type lectin receptors); (2) integrins (the complement receptors); (3) Fc receptors (Ig receptors); (4) leucine-rich repeat receptors (or CD14, LPS receptors); (5) scavenger receptors (receptors of sialic acid derivatives); and tyrosine kinase receptors [49]. As distinct from these, TLRs are not directly involved in the uptake of foreign material; however, they do take part in the regulation of phagosome formation and in inflammatory reactions [50].
Methacrylated gelatin hydrogels as corneal stroma substitutes: in vivo study
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Cemile Kilic Bektas, Ayse Burcu, Gokhan Gedikoglu, Hande H. Telek, Firdevs Ornek, Vasif Hasirci
Foreign body reaction is a normal response of the tissues to any biomaterial regardless of their immunogenic, toxic, and physically and chemically stable nature. The response of the body can be in the form of thrombosis, infection, inflammation and fibrosis that attracts phagocytic cells. It is thought that the phagocytes interact with the proteins adsorbed on the surface of the biomaterial upon implantation and this leads to a cascade of reactions for tissue repair [55–58]. A reaction following implantation, therefore, is a normal reaction of the body to repair the damaged tissue. The higher number of giant cells observed in 1GL implant is most probably due to the larger dimension of the implanted construct.
Focal therapy for localized cancer: a patent review
Published in Expert Review of Medical Devices, 2021
Jette Bloemberg, Luigi Van Riel, Dimitra Dodou, Paul Breedveld
With regard to the treatment means, most patents describe an instrument using energy. The low preference in using matter to treat cancer might be explained by the long-term toxicity concerns of remaining matter, especially non-biodegradable matter [218,219]. Energy does not possess this risk of long-term toxicity, as the energy is removed from the body together with the removal of the energy source. Another barrier of matter is the body’s labeling of foreign particles by opsonization to stimulate the removal of those foreign particles [218]. In opsonization, the foreign particles are covered with nonspecific proteins to make them more visible to phagocytic cells, so phagocytosis can occur [218,220].
Recommendations to maintain immune health in athletes
Published in European Journal of Sport Science, 2018
Numerous studies over the last 35 years indicate a decrease in immunity and an increase in upper respiratory infection (URI) symptoms in athletes during periods of heavy training and competition (Peters & Bateman, 1983; Tomasi, Trudeau, Czerwinski, & Erredge, 1982; Walsh et al., 2011b). Experts attribute these observations to the various challenges athletes encounter during heavy training and competition, e.g. heavy exercise and life stress (Figure 1). Psychological stress and physical exertion have long been known to influence the sympathetic–adrenal axis and pituitary–adrenal axis since the pioneering work of Walter B Cannon (who coined the ‘fight or flight’ response) and Hans Selye (who coined the term ‘stress’) in the 1930s. These common pathways and shared effector limbs for the body’s response to stress in its many forms give rise to increases in circulating catecholamines and glucocorticoid hormones: these hormones are widely acknowledged to alter immune function (Dhabhar, 2014) (Figure 2). The immune system is highly organised to provide a potent, multi-layered defence against attack from pathogenic microorganisms including viruses, bacteria, fungi and protozoa; in addition, the immune system provides defence against cancer through anti-tumour activity. The various cellular and soluble elements in the immune system’s armoury against infectious agents can broadly be divided into innate (non-specific) and acquired (specific) arms. On encountering a pathogen the first line of defence, the innate immune system, is activated: the innate immune system comprises physical and chemical barriers (e.g. the skin and mucosal membranes) and phagocytes (e.g. neutrophils, monocytes, etc.) that ingest and kill microorganisms along with other non-specific killer cells. The second line of defence, the acquired immune system, is highly specialised, yet slower to deploy than the innate immune system: the acquired immune system comprises the lymphocytes; specifically, T and B lymphocytes that proliferate and serve a multitude of roles including B cell antibody production, cytotoxic T cell killing and the development of T memory cells so that an augmented response can be mounted on subsequent pathogen exposure (the scientific basis for Edward Jenner‘s discovery of vaccination). Although sub-dividing the immune system into innate and acquired arms affords a simple description, this distinction is rather crude: the innate and acquired immune systems are actually very much intertwined; for example, the processes of antigen presentation and recognition and pathogen exclusion require cells of the innate and acquired immune system to work together in harmony. For a more comprehensive review of the inner-workings of the immune system and the neuro-endocrine responses to stress readers are directed elsewhere (Dhabhar, 2014; Gleeson, Bishop, & Walsh, 2013). The aim of this mini-review is to provide new insights about and, where possible, evidence-based recommendations for coping with the various challenges that athletes encounter on immune health: including, heavy exercise, life stress, sleep disruption, environmental extremes and nutritional deficits (Figure 1).