Defences mechanisms

Heavy metals are well known for inducing the synthesis of a family of metalbinding proteins called metallothioneins (Frazier, 1986). These low-molecular-weight proteins (6000 Da) contain 25-30% cysteine, enabling them to sequester divalent metals such as cadmium, copper, mercury and zinc from the lb and 

edulis mussels (Gowlan et al., 2002). Thus, GST activity correlates with 5-6-ring PAHs rather than with the total burden of PAHs in tissues. 

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For many of the drugs, however, the active constituents are not (yet) known the examination of their activity is thus often rendered more difficult in that experience of its administration over a long period of time is required. In these cases, it is often said that the drug concerned stimulates the body s own defence mechanisms formerly, the administration of such drugs was called nonspecific stimulant therapy, nowadays the concept of immunostimulation is used or paramunity inducers [I-6]. 

Primary irritants cause inflammation. Inflammation is one of the body s defence mechanisms. It is the reaction of a tissue to harm which is insufficient to kill the tissue and is typified by... 

Respirable particulates Particulates in the size range that can pass through the defence mechanisms in the human body and enter the lungs during inhalation. 

Primary irritants cause inflammation. Inflammation is one of the body s defence mechanisms. It is the reaction of a tissue to harm which is insufficient to kill the tissue and is typified by constriction of the small vessels in the affected area, dilation of the blood vessels, increased permeability of the vessel walls, and migration of the white blood and other defensive cells to the invading harmful chemical. The aim is to concentrate water and protein in the affected area to dilute the effect and wash away the chemical. Production of new cells is speeded up and contaminated surface cells are shed. 

Non-specific defence mechanisms 4.6.2 Suppressor cells (Ts cells)... 

The body possesses an efficient natural defence mechanism which restricts microorganisms to areas where they can be tolerated. A breach of this mechanism, allowing them to reach tissues which are normally inaccessible, results in an infechon. Invasion and multiplicahon of the organism in the infected host m result in a pathological condihorr, the clirrical entity of disease. 

Complement comprises a group of heat-labile serum proteins which, when activated, are associated with the destruction of bacteria in the body in a variety of ways. It is present in low concentrations in serum but, as its action is linked intimately with a second (specific) set of defence mechanisms, its composition and role will be dealt with later in the chapter. 

Specific defence mechanisms (adaptive immune system)... 

Passively acquired immunity involves no work on the part of the body s defence mechanisms, and produces immediate protection of short duration. 

A patient s resistance is cmcial in determining the outcome of a medicament-borne infection. Hospital patients are more exposed and susceptible to infection than those treated in the general community. Neonates, the elderly, diabetics and patients traumatized by surgeiy or accident m have impaired defence mechanisms. People suffering fiom leukaemia and those treated with immunosuppressants are most vulnerable to infection there is a strong case for providing all medicines in a sterile form for these patients. 

Weber FJ, S Isken, JAM de Bout (1994) Cis/trans isomerization of fatty acids as a defence mechanism of Pseudomonas putida strains to toxic concentrations of toluene. Microbiology (UK) 140 2013-2017. 

Del Boccio, C., Laprenna, D., Porreca, E., Pennilli, A., Savini, F., Feliciani, P., Ricci, G. and CuccuruUo, F. (1990). Aortic antioxidant defence mechanisms time-related changes in cholesterol fed rabbits. Atherosclerosis 81, 127-135. 

The free-radical defence mechanisms utilized by the brain are similar to those found in other tissues. The enzymes SOD, catalase, glutathione peroxidase, and the typical radical scavengers, ascorbate, vitamin E and vitamin A are present in the brain, as they are in peripheral tissues. However, the brain may actually be slightly deficient in some of these defence mechanisms when compared to the amounts present in other tissues. 

Shindo, Y., Witt, E. and Packer, L. (1993). Anti-oxidant defence mechanisms in murine epidermis and dermis and their responses to ultraviolet light. J. Invest. Dermatol. 100, 260-265. 

Wohaieb, S.A. and Godin, D.V. (1987). Alterations in free radical tissue-defence mechanisms in streptozocin-induced diabetes in rat. Diabetes. 36, 1014-1018. 

Particulate Reactions 2.1.2 Phagocyte-derived Free 248 2.5.2 Alzheimer s Disease 3. Antioxidant Defence Mechanisms and 252... 

Catalase is one of the oldest known enzymes and was developed when life became aerobic, i.e. when organisms started to use oxygen. When a cell uses oxygen in its metabolism HP is very often produced as a by-product. However HP is toxic to the cells, so they need some defence mechanism. Catalase was invented by the evolution to protect living cells from HP. 

So far there is no known defence mechanism against dialdehydes in living cells and the risk for adaptation should therefore be minimal. 

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