Host tissue

Modem cancer therapy has been primarily dependent upon surgery, radiotherapy, chemotherapy, and hormonal therapy (72) (see Chemotherapeutics,anticancer Hormones Radiopharmaceuticals). Chemotherapeutic agents maybe able to retard the rate of growth, but are unable to eradicate the entire population of neoplastic cells without significant destmction of normal host tissue. This serious side effect limits general use. More recentiy, the immunotherapeutic approach to cancer has involved modification and exploitation of the cellular and molecular mechanisms in host defense, regulation of tissue proliferation, tissue differentiation, and tissue survival. The results have been more than encouraging. 

Reaction of the host tissue to metallic implants is affected by many factors including shape and size of the implant, movement between the implant and tissue, extent of corrosion attack, general degradation of the implant, and the biological activity of the resulting by-products of corrosion or degradation. 

A viral tropism is the specifity of a vims for particular host tissues and cells. 

The conditions for production of TTX and STX by bacteria are unknown. The low levels of TTX and STX observed in laboratory cultures may indicate that the host environment has not been duplicated. Likely, the composition of culture medium and other physicochemical parameters for TTX and STX production have not yet been defined in vitro. Conversely, bacteria may actually produce only small amounts of TTX and STX in vivo that accumulate in host tissues over long time intervals. 

Prions are responsible for the so-ealled slow virus diseases, a distinet group of unusual neurologieal disorders. They are believed to be markedly resistant to inactivation by many ehemieal and physical agents but because they have not been purified, it is at present diffieult to state whether this is an intrinsic property of prions or whether it results fkm the proteetive effect of host tissue present. Certainly very high coneentrations of a bioeide aeting for long periods may be necessary to produee inactivation. 

The selection of which gene(s) (or cDNA) to use depends upon the end product required, the carotenoid content of the host tissue and the need to... 

Infection Inflammatory response to invasion of normally sterile host tissue by microorganisms. 

The key factor in the development of sepsis is inflammation. Inflammation is intended to be a local and contained response to infection or injury. Infection or injury is controlled through pro- and anti-inflammatory mediators. Pro-inflammatory mediators facilitate clearance of the injuring stimulus, promote resolution of injury, and are involved in processing of damaged tissue.1,13-16 In order to control the intensity and duration of the inflammatory response, antiinflammatory mediators are released that act to regulate pro-inflammatory mediators.15-16 The balance between pro- and anti-inflammatory mediators localizes infection/injury of host tissue.13-16 However, systemic responses ensue when equilibrium in the inflammatory process is lost. 

Acute GVHD usually is not evident until the time of engraft -ment, when donor lymphoid elements begin to proliferate. The primary targets of immune-mediated destruction of host tissue by donor lymphocytes in acute GVHD are the skin, liver, and GI tract.44 A diffuse maculopapular rash on the face, truck, face, extremities, palms, soles, and ears is the usual sign of acute GVHD of the skin. In more severe cases, it can... 

In some helminth infections, a migration through various body tissues is essential for maturation, as in ascarasis or schistosomiasis, whereas in other infections, the larva leaves the egg and simply matures in the intestinal tract, as in trichuriasis and enterobiasis. Host tissues involved vary depending upon the parasite. In severely immunocompromised patients, sites may be involved that are not involved in normal hosts. 

Macarisin D, Cohen L, Eick A, Rafael G, Belausov E, Wisniewski M and Droby S. 2007. Penicillium digitatum suppresses production of hydrogen peroxide in host tissue during infection of citrus fruit. Phytopathology 97(11) 1491-1500. 

Marker Studies. Cells (e.g., bone marrow, stem cells) transduced with a vector expressing a marker or reporter gene used to distinguish it from other similar host tissues. 

Another reason for complexity of cell-activation mechanisms resides in the end response of neutrophils - that is, the delivery of cytotoxic products. Whilst these products are highly lethal towards pathogens, they can also attack and destroy host tissues, and this can have deleterious effects on tissue function. Complex intracellular signalling mechanisms to activate these cytotoxic pathways also guards against non-specific activation, which could lead to host tissue damage. 

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