Growth-promotion assay

The establishment of a physicochemical potency assay for biosynthetic human growth hormone provides an interesting example of an approach for validation of such assays. The hypophysectomized rat growth promoting assay used tradionally has a precision of approximately 15-20% RSD, which is clearly not adequate for controlling well-characterized products. In order to select a suitable assay to replace the in-vivo bioassay, the biopotencies... 

Two assays were developed that measure the potency of the FGF-4 transgene carried by Ads FGF-4. In the first case, a one-step growth-promotion assay is conducted on normal, human retinal pigment epithelial cells (ARPE-19). The assay measures metabolic activity (Alamar blue dye metabolism) following infection of ARPE-19 cells with a serial dilution of the virus. The increase in metabohc achvity was measured in relation to a mock-infected control. This increase correlates with FGF-4 produchon determined by an FGF-4 ELISA, increased de-novo DNA synthesis measured by BrdU incorporation, and an increase in cell number. This procedure is therefore an appropriate in-vitro efficacy measure, indicating that the FGF-4 transgene product is biologically active. 

Fig. 6.8 One-step growth-promotion assay. Mock-infected ARPE-19 cells (A) and ARPE-19 cells infected with the negative control AdSLacZ (B) or Ad5FGF-4 (C) on day 1 post infection. (Original magnification, x4.)...

Fig. 6.9 Parallel line analysis of a growth-promotion assay dataset, using PLA software. This identified five consecutive dilutions of the positive control, and six consecutive dilutions of the sam-...

Various assay methods have been used to detect the presence of inhibitory substances. These include some of the classical tests used by investigators of growth-promoting substances—i.e., the various Avena coleoptile assays which utilize intact, decapitated, or isolated cylinders and the split pea stem test. Effects on seed germination and seedling shoot or root growth and development have also been measured in addition to other visible expressions of inhibition. Details of many of these tests have been compiled by Mitchell et al. (99). Tests have been carried out in Petri dishes, with various solution culture techniques, and by sand and soil culture. Effects so measured may or may not be similar to those obtained under field situations— i.e., the establishment of inhibition under controlled conditions pro-... 

Several microbiological procedures for assaying CF have been described in the literature. In general, these methods are designed to measure CF content in a biological fluid or specimen. They all make use of the growth promotion of L. citrovorum 8081, or cere-visiae, as it has been renamed. Before CF was isolated... 

Although B12 can be assayed biologically in mice, chicks, and rats, especially with the use of radioactive cobalt, the microbiologic method of assay is preferred because it is economical and sensitive. One serious drawback of bacterial Bi2 assay procedures is the lack of specificity and sensitivity. The extreme sensitivity (1 X 10 12 g) and relative freedom of stimulation in blood, serum, and urine make protozoa the choice assay tools (B17, F3, H19). The most specific is O. malhamensis (B17, F3) Euglena is known to be stimulated by pseudo-B12 (F2). Serum and blood from normal subjects have a growth-promoting effect on Euglena (M12) above that seen with Ochromonas. The reason for such... 

Three plant growth promoters and five compounds with insecticidal or insect repellant activity have been identified from marine organisms. In addition, a number of extracts have been shown to be active in one or both of the assay systems. 

Situ, C., E. Gratters, P. van Wichen, et al. 2006. A collaborative trial to evaluate the performance of a multi-antibiotic enzyme-linked immunosorbent assay for screening five banned antimicrobial growth promoters in animal feeding stuffs. Anal. Chim. Acta 561 62-68. 

Several bioassy techniques have been developed which allow testing of biological materials produced In small quantities. The excised wheat coleoptlle test 155) has versatility In detecting plant growth promoters and and growth Inhibitors. The assay Is... 

Tube assays use liquid medium, and growth inhibiting and growth promoting systems differ. 

Antibiotics and other drugs have been applied to farm animals ranging from catfish to honeybees, for the prevention or treatment of diseases, elimination of parasites, or growth promotion. Transfer of these substances to humans through the food chain is a serious concern, and antibiotic levels in various foods are often the subject of strict regulation. Immrmo-assays developed for these molecules are highly... 

In this entry, the authors present an overview of the LC-MS of naturally occurring steroids in biological samples, which was published from January 2001 to June 2006. Steroids are divided into six categories, based on their stmctures and functions, and no attention has been paid to steroid hormones used as growth promoters of animals and used in sports doping. This entry also does not take up references on the in vitro assays for the measurement of enzyme activity using a steroid as the substrate. 

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