Disease tissue

Allochthonous flora Organisms that are not indigenous to the soil but that enter soil by precipitation, diseased tissues, manure, and sewage. They may persist for some time but do not contribute in a significant way to ecologically significant transformations or interactions. 

Cobalt-60 cancer therapy. Gamma rays from the rotating radiation source are concentrated at the location of the diseased tissue. 

The cl mg discovery process can be envisioned as four interconnected phases (see Figure 8.1). Generally, these are the acquisition of chemicals to be tested for biological activity, the determination of the activity of those chemicals on biological systems (pharmacodynamics), the formulation of the most active of these for therapeutic testing in humans (pharmaceutics), and the determination of adequate delivery of the active drug to diseased tissues (pharmacokinetics). Each of these collections of processes is interconnected with the others and failure in any one of them can halt the development process. It is worth considering each process separately, as well as the relationships between them. 

Limitations are obvious if the diseased tissue does not differ from normal tissue or successfully treated tissue in respect of the above-mentioned criteria. Under these conditions, even a contrast agent with high absorption of X-rays is of no help. Another drawback is the short-lasting contrast which requires repeated injections if the diagnosis is missed during the first scan or if persistent visualization of a lesion is required during an interventional procedure. 

In macromolecular dmg delivery systems, dmgs are attached to polymeric compounds, such as synthetic polymers [60], dendrimers [61], and antibodies [62], in order to enhance the delivery of the active substance to the diseased tissue and to reduce the toxicity to healthy tissue. The use of macromolecular delivery systems provides several advantages extension of the half-life of the dmg, the ability to introduce targeting moieties into the carrier, the possibility of triggered dmg release, and the aforementioned reduced cytotoxicity. 

Their activities may be altered in diseased tissues (eg, cirrhosis), affecting drug metabolism Genotyping the P450 profile of patients (eg, to detect polymorphisms) may in the future permit individualization of drug therapy... 

Sanderson JD, Moss MT, Tizard ML, Hermon-Taylor J Mycobacterium paratuberculosis found in Crohn s disease DNA in Crohn s disease tissue. Gut 1992 33 890-896. 

Walmsey RS, Anthony A, Sim R, Pounder RE, Wakefield AJ Absence of Escherich ia coli, Listeria monocytogenes and Klebsiella pneumoniae antigens within inflammatory bowel disease tissues. J Clin Pathol 1988 51 657-661. 

The antibody brings about its effect by inhibiting angiogenesis (the formation of new blood vessels), a process required to support tumour growth. Specifically, the antibody binds human vascular endothelial growth factor. This prevents the latter from binding to its cell surface receptor, a process central to triggering new blood vessel formation in both normal and diseased tissue. 

The approach involves a passage of direct electric current through the tumor, thus destroying the diseased tissue through a number of electrochemical events. 

Virchow, who was largely responsible for the acceptance of the cell theory, developed microscopy of cells from normal and diseased tissues as a major tool (histopathology) in the clinical armory. He believed the vital functions of the cell, growth, maintenance, and multiplication were discharged by its nucleus the specialised, distinguishing functions were made possible by the extranuclear constituents. In a Sunday evening lecture in Edinburgh in 1868, On the Physical Basis of Life , Thomas Huxley described cells as protoplasmic masses usually... 

Endothelial permeability Transporter proteins Enzymatic/metabolic activity Disease Tissue composition (drug sequestration) Dose size/volume Conformation Chemical stability Enzymatic stability... 

Studies in the last few years in the fields of genomics and proteomics have made available to us an unprecedented number of targets with which to search for new drug candidates. While knowledge of a particular gene sequence, for example, may not directly point to a specific disease when the sequences are first determined, investigations of their presence in normal and diseased tissues could well lead to a quantitative in vitro test system that is not available today. The same can be said for the field of proteomics, but final decisions on the value of these new technologies cannot be made for some years to come. 

The potential contribution of stem cells to medical treatment lies in then-capability to differentiate and grow into normal, healthy cells. Using pluripotent stem cells, scientists are devising means to culture them in the laboratories and coax them to grow into various specialized cells. Rather than gene therapy, with stem cells we have the potential of cell therapy to repair our diseased tissues and organs. This will circumvent the lack of donor organs. Stem cells also provide the possibility for healthy cells to cure disabilities such as strokes, Parkinson s disease, and diabetes. 

Sufficient stable loading of drug in order to reach disease site with liposomes loaded with drug at a level needed to achieve therapeutic efficacy Extravasation into diseased tissue (tumor or inflamed sites)... 

A unique use is its ability to locate brain tumors. It is a weak radioisotope able to attach itself to diseased tissue rather than healthy tissue, thus making detection possible. 

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