Biological assessment cell components

The deterministic effects develop as consequences of injuries or deaths of many cells. Their appearances and severities depend on the radiation sensitivities of the cell components of exposed tissues. The cellular injuries or the radiation-induced functional alterations might serve for the assessment of absorbed doses, too. These parameters are called biological indicators or dosimeters of radiation injury. The radiation sensitivity like mortality of cells can be determined. 

The use of Upid bilayers as a relevant model of biological membranes has provided important information on the structure and function of cell membranes. To utilize the function of cell membrane components for practical applications, a stabilization of Upid bilayers is imperative, because free-standing bilayer lipid membranes (BLMs) typically survive for minutes to hours and are very sensitive to vibration and mechanical shocks [156,157]. The following concept introduces S-layer proteins as supporting structures for BLMs (Fig. 15c) with largely retained physical features (e.g., thickness of the bilayer, fluidity). Electrophysical and spectroscopical studies have been performed to assess the appUcation potential of S-layer-supported lipid membranes. The S-layer protein used in aU studies on planar BLMs was isolated fromB. coagulans E38/vl. 

The enzymatic activity in soil is mainly of microbial origin, being derived from intracellular, cell-associated or free enzymes. Only enzymatic activity of ecto-enzymes and free enzymes is used for determination of the diversity of enzyme patterns in soil extracts. Enzymes are the direct mediators for biological catabolism of soil organic and mineral components. Thus, these catalysts provide a meaningful assessment of reaction rates for important soil processes. Enzyme activities can be measured as in situ substrate transformation rates or as potential rates if the focus is more qualitative. Enzyme activities are usually determined by a dye reaction followed by a spectrophotometric measurement. 

Host-resistance assays can be used to assess the overall immunocompetence of the humoral or cell-mediated immune systems of the test animal (host) to fend off infection with pathogenic microbes, or to resist tumorigenesis and metastasis. These assays are performed entirely in vivo and are dependent on all of the various components of the immune system to be functioning properly. Thus, these assays may be considered to be more biologically relevant than in vitro tests that only assess the function of cells from one source and of one type. Since these assays require that the animal be inoculated with a pathogen or exogenous tumor cell, they cannot be performed as part of a general preclinical toxicity assessment, and are thus classified as Type 2 tests in the revised Redbook. These assays are also included as Tier II tests by the NTP. 

Methods for assessing or modeling of the responses of the human immune system to vaccines are critical components of any effort to understand the relationship between immunogenicity and either a positive or a negative outcome of vaccination. Decades of research have yielded many useful in vitro methods that enable the isolation and molecular dissection of selected components (modulators or cell types) of an immune system, whether mouse or human. While of hmited scope biologically, these systems have elucidated the modulators and cell types responsible for certain facets of humoral or cellular immunity. These systems have also been employed to define the roles that modulators and specific cell types play in particular aspects of an immune response. Missing, until recently, was an in vivo setting in which to study the human immune system. 

---