General assay

Of the various chemical assays that have been developed for the saxitoxins (75,76), that described by Bates and Rapoport, based on the oxidation of saxitoxin to a fluorescent derivative, has proved to be the most useful. Other assay methods have been developed from it (77-79). The Bates and Rapoport method is virtually insensitive to the N-l-hydroxyl saxitoxins as originally described and so, like the presently available immunoassays, fails as a general assay for either concentration or toxicity. However, it is quite sensitive for those toxins it does detect and has been the basis for other useful methods. 

The magnesium-reduced beryllium pebbles generally assay 96% beryllium and are always associated with residual magnesium and slag. These pebbles are purified to about 99.5% by vacuum induction melting in beryllia crucibles at temperatures of about 1400 °C. The ingots are machined and machined scarf is milled to produce beryllium powder. The ground metal powder is pressed and sintered under vacuum. The product is called vacuum hot-pressed beryllium, and this is machined for component manufacture. 

Measurement of catecholamine metabolites can provide insight into the rate of release or turnover of catecholamines in the brain. In clinical studies, metabolites of catecholamines are generally assayed in the CSF because the large quantities derived from the peripheral sympa-thomedullary system obscure the small contribution from the brain to urinary concentrations. However, acid metabolites are actively excreted from the CSF more reliable estimates of turnover in the brain are obtained when this transport process is blocked by pretreatment with the drug probenecid. 

The platinum sponge used in this preparation should be either 99.99 or 99.999% pure. All other chemicals should be reagent grade. Only KCN, which generally assays 97-98% pure, is recrystallized from absolute methanol.5 It is dried at 50° for 2 hours before it is weighed, as are the KBr and [N2H6]S04. Distilled water is used throughout the entire preparation. 

Vitamins are generally assayed in one of two different ways. The first route uses a microbiological technique. Here, a specialist organism is used, the growth of which is dependent on the concentration of the particular vitamin of interest. 

General Assay for Kinetic Resolution of Esters (Kazlauskas Test)... 

Already-established general assays and tests (e.g., titrimetric method of water determination, identification test) should also be validated to verify their accuracy (and absence of possible interference) when used for a new product or raw material. 

The amino acid composition of peptides is generally assayed by carrying out acid hydrolysis with 6 M hydrochloric acid, followed by determination of the individual amino acids by HPLC. Various types of HPLC have been employed to separate amino acids, but reversed-phase chromatography on Cigcoiumns is the most commonly system used. Detection of amino acids normally involves derivatization, since their maximum absorbance is at 214 nm in which many other compounds also can absorb. The most frequently used derivatizing agents are dansyl chloride, phenyl isothiocyanate and o-phthaldialdehyde. 

HTS-compatible assay technologies for general assay formats to target classes or types adapted and updated from [4])... 

General Assay Urease Activity in Problem Soils. Tu (14) examined urease activity in clay loam soils incubated with various pesticides. He observed increased levels of microbial urease activity with carbofuran- and ethoprop-amended soils (Table I). These results suggest that activity levels of specific indigenous soil enzymes may be influenced by certain pesticides applied to... 

General Assay Enzyme Activities in an Enhanced Soil. Reed et al. (131 characterized cell-free culture filtrates of actinomycete, bacterial and fungal isolates using a spectrophotometric method for assaying the activities of rhodanese, phosphatase and phosphodiesterase. Elevated enzyme levels, expressed as specific activity, of several of the microbial isolates cultured in the presence of selected pesticides indicated a potential for... 

Evaluation of Phagocyte Activity. As mentioned above, the ICH S8 guidance on immunotoxicity testing calls for follow-up testing as necessary. If it is determined that follow-up testing is required and the cell types affected in the initial evaluation of a test article are not involved in the more general assay for immune function (the T-Dependent Antibody Response Assay), specihc assays may be conducted to assess the function of a particular cell type such as... 

TABLE 5.1-2 Algorithm for Immunotoxicity Evaluation Using Host Resistance Assays Generalized Assay to Evaluate the Overall Health of the Immune System... 

C.J. Zea, N.L. Pohl, General assay for sugar nucleotidyltransferases using electrospray ionization mass spectrometry, Anal. Biochem. 2004, 328,196-202. 

Chlorinated hydrocarbons are frequently encountered in ground-, drinking, and waste waters. A method for the detection of organic chlorides has been developed [6]. It makes use of the Fujiwara color reaction, which is a general assay for organic compounds that contain two or more chlorine atoms. Reaction of alkaline pyridine with polychlorinated organic compounds yields a red fluorescent chromophore whose formation is detected. The formation of the fluorophore is irreversible, so the device is a probe rather than a sensor. 

In principle, all DNA sequences that are known as species specific can be used for the development of an assay for the detection of DNA from specific animals, plants, or bacteria. In control experiments it must be shown that no other DNA fragments are amplified using the primers chosen. Generally, assays with primers and a specific... 

The concept used in the endonuclease assay was the dimination of RET by enzymatic breakage of a covalently linked D-A pair. This concept has been applied in avariety of other circumstances, including assay of an HIV-1 endonuclease, which is involved in integrating the HIV into the host DNA. RET has also been used to measure the activity of an HIV protease, proteolytic cleavage of linked derivatives of GEP," and the activity of ribozymes in cleaving RNA and as the basis of a general assay for DNA cleavage. ... 

Smelting to produce matte, discard slag and a high lead fume, also containing any other volatile elements, such as arsenic. The matte can then be converted in the same or a separate furnace to produce blister copper, converter slag and fiime of the general assay shown in Table VII. 

Two general assay methods are now available. One is colorimetric it depends on the isolation of ALA from an incubated mixture, its separation from aminoacetone by resin chromatography, its conversion to a pyrrole by condensation with acetylacetone, and the production of a colored derivative of the pyrrole with Ehrlich s reagent containing Hg " to remove interfering SH groups [Mauzerall and Granick, 49,52]. 

Todd, M.J. Gomez, J. (2001) Enzyme kinetics determined using calorimetry a general assay for enzyme activity . Anal. Biochem. 296,179-187. 

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