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9 Function-Based Detection
Pages 149-154

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From page 149...
... The many unknowns surrounding Gulf War Syndrome have prompted soldiers to act independently in order to protect themselves from compounds that may not be detected by existing equipment. The ad hoc employment of an uncharacterized function-based detection system in the front lines indicates the need for more research in this area.
From page 150...
... In the following examples, hybrid systems exploit part of the functional process within a cell-based response system, even as they are targeted at a specific characterized function. The canary-on-a-chip concept,5 which uses genetically engineered B cells or B lymphocytes with the appropriate antibody incorporated into the genome and displayed on the cell surface, is an example of a biosensing system that exhibits characteristics of a functional detector but is reliant on having a specific TABLE 9.1 Type of information Provided by Various Recognition Systems Recognition Functional Specific Generic Detection Element information Identifications and Classification Antibodies Nucleic acids Synthetic ligands Enzymes/cellular chemistry Ion channel/receptors Cell Whole organisms Relies on a specific binding event (e.g., gene Probe primer sets for a given organism or antibody antigen binding)
From page 151...
... Isolated fish chromatophore cells can also be used as a detection system.'° This approach exploits the ability of living chromatophores to respond to many active substances such as bacterial toxins; the response of the chromatophore is measured as changes in the appearance of the cell due to intracellular activity of the colorants." Tissue biosensors made from immobilized whole-cell photosynthetic microorganisms have been developed for airborne chemical warfare agents and simulants. This is based on fluorescence induction by living photosynthetic tissue.
From page 152...
... Exposure to toxicants causes changes in their characteristic fluorescence induction curves with resultant changes in photochemical yields.'2 Neuronal tissue is the target of many toxins—specifically, nerve agents—and represents an infommation-rich source of material for the development of sensing systems. Cultured neuronal networks based on murine spinal cord, frontal cortex, and auditory cortex tissues have been cultured on microelectrode arrays.'3 The system contains all the metabolic and electrophysiological mechanisms of the parent tissue.
From page 153...
... FINDINGS AND RECOMMENDATIONS Finding 9-1: Functional detection systems currently do not have the sensitivities or response times needed for detect-to-warn applications; further, they have not been demonstrated against most of the biological agents. However, they offer considerable potential for filling flhe gap that is not currently being addressed by specific identifier systems—that is, they could provide a generic detection capability that The severity of this limitation is not clear.
From page 154...
... Finding 9-2: Because of the requirement for sterility when using biological materials as detection elements, function-based detectors that utilize cells and operate continuously may have limitations if intact threat organisms are required for detection. Recommendation 9-2: Research is needed to explore the limits of cell-based detection systems, including requirements for sample collection and sterilization as well as methodologies for extending the functional life of the sensing elements, both in operation and storage of reagents (cells)


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