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Cytokines biological role

Although oxygen radicals are destructive to islet cells, the inability of nicotinamide, Probucol, and other free radical scavengers to completely prevent cytokine mediated islet destruction suggests that other cytotoxic mechanisms may be involved in cytokine-induced islet-cell lysis. The possible interactions of superoxide with nitric oxide resulting in the generation of peroxynitrite and hydroxyl radicals may contribute to islet-cell lysis. The chemistry of these free radical interactions, and potential biological roles t)f these toxic radicals are reviewed in this book (see Chapter 1). [Pg.186]

Gaffen SL. Biology of recently discovered cytokines interleukin-17 -aunique inflammatory cytokine with roles in bone biology and arthritis. Arthritis ResTher 2004 6 240-247. [Pg.125]

The number of known cytokines, as well as the diversity of biological functions, have led to a very complex and often confusing picture of the immunologic and nonimmunologic processes involved. The role of cytokiaes in local or systemic homeostatic mechanisms related to physiological functions may be utilized therapeutically for treatment of cancer and a variety of other diseases (2). Pharmaceutical research and development efforts surrounding lL-1 are typical examples of the cytokine inhibition approach to chronic inflammation research (2). [Pg.32]

Cytokines are small, short-lived proteins and important mediators of local intercellular communication. They play a key role in integrating responses to a variety of stimuli in immune and inflammatory processes. By binding their cognate receptors on target cells in their immediate vicinity, these molecules participate in many important biological activities including cell proliferation, activation, death and differentiation. In... [Pg.1082]

In conclusion, ET is a polyfunctional cytokine that affects monocytes as well as vascular smooth muscle cells, anterior pituitary cells, and renal mesangial cells. In the biologic interface between ischemic or injured endothelium and monocytes, neutrophils, or lymphocytes, ET may play a significant role. [Pg.73]

Most cytokines act upon, or are produced by, leukocytes (white blood cells), which constitute the immune and inflammatory systems (Box 8.1). They thus play a central role in regulating both immune and inflammatory function and in related processes such as haematopoiesis (the production of blood cells from haematopoietic stem cells in the adult bone marrow), as well as in wound healing. Indeed, several immunosuppressive and anti-inflammatory drugs are now known to induce their biological effects by regulating production of several cytokines. [Pg.205]

It appears that TNF-R55 is capable of mediating most TNF activities, whereas the biological activities induced via the TNF-R75 receptor are more limited. For example, TNF s cytotoxic activity, as well as its ability to induce synthesis of various cytokines and prostaglandins, is all mediated mainly/exclusively by TNF-R55. TNF-R75 appears to play a more prominent role in the induction of synthesis of T-lymphocytes. All of the biological activities mediated by TNF-R75 can also be triggered via TNF-R55, and usually at much lower densities of receptors. TNF-R75 thus appears to play more of an accessory role, mainly to enhance effects mediated via TNF-R55. [Pg.259]

The family of heterotrimeric G proteins is involved in transmembrane signaling in the nervous system, with certain exceptions. The exceptions are instances of synaptic transmission mediated via receptors that contain intrinsic enzymatic activity, such as tyrosine kinase or guanylyl cyclase, or via receptors that form ion channels (see Ch. 10). Heterotrimeric G proteins were first identified, named and characterized by Alfred Gilman, Martin Rodbell and others close to 20 years ago. They consist of three distinct subunits, a, (3 and y. These proteins couple the activation of diverse types of plasmalemma receptor to a variety of intracellular processes. In fact, most types of neurotransmitter and peptide hormone receptor, as well as many cytokine and chemokine receptors, fall into a superfamily of structurally related molecules, termed G-protein-coupled receptors. These receptors are named for the role of G proteins in mediating the varied biological effects of the receptors (see Ch. 10). Consequently, numerous effector proteins are influenced by these heterotrimeric G proteins ion channels adenylyl cyclase phosphodiesterase (PDE) phosphoinositide-specific phospholipase C (PI-PLC), which catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) and phospholipase A2 (PLA2), which catalyzes the hydrolysis of membrane phospholipids to yield arachidonic acid. In addition, these G proteins have been implicated in... [Pg.335]

UV-irradiated cells. Using cell-free cytosolic keratinocyte extracts, Simon and colleagues26 confirmed the role of membrane oxidation in NF-kB activation. Particularly important aspects of the experimental design employed by Simon and colleagues was the use of keratinocytes versus cells derived from a cervical cancer patient, and the use of biologically relevant UVB (290 to 320 nm) radiation versus UVC (200 to 290 nm) radiation, which is filtered out by the atmospheric ozone layer and does not reach the earth s surface. Overall, these data indicate that the activation of cytokine transcription, a step essential for the induction of immune suppression, can occur independently of UV-induced DNA damage and suggest that membrane lipid oxidation can serve as a UV photoreceptor. [Pg.263]


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