Trichloroacetic acid test

The Talc-Resin-Trichloroacetic Acid Test for Screening Radioiodinated Polypeptide Hormones... 

The first observations on adverse renal effects of cadmium (Cd) exposure in humans were made by Friberg in the late 1940s [1]. He reported a high prevalence of proteinuria (65% using the nitric acid test and 81% using the trichloroacetic acid test) in Cd-exposed workers. 

The same is true of the trichloroacetic acid test (10 ml at 55% per 100 ml of wine). The mixture is heated in a waterbath at 100°C for 2 mn and turbidity is observed after 15 min at room temperature. This test is hardly more effective than the Bentotest if the addition of excessive quantities of bentonite to wine is to be avoided. 

Mackay JM, Fox V, Griffiths K, et al Trichloroacetic acid Investigation into the mechanism of chromosomal damage in the in vitro human lymphocyte cytogenetic assay and the mouse bone marrow micronucleus test. Carcinogenesis 16(5) 1127-1133, 1995... 

Current efforts favor tumor cell line tests, conducted by the National Cancer Institute (NCI) drug development program [62]. In the current NCI anticancer screen, each compound is tested against 60 human tumor cell lines derived from several cancer types (lung, colon, melanoma, kidney, breast, ovary, brain, leukemia). The tumor cells are seeded on 96-well microtiter plates and pre-incubated for 24 h. The test agents are then added to the wells (five 10-fold dilutions 0.01 -100 pmol/1) and are incubated for 48 h with the tumor cell lines. At the termination of the assay, the cells are fixed in situ with trichloroacetic acid (TCA), washed and dried. Sulforhodamine B (SRB), a dye that binds to the basic amino... 

The incubation digest (7.0 ml) contained 1 ml of 0.022 M phenyl phosphate 2.5 ml of 0.1 M acetate buffer, pH 5.0 0.5 ml of test enzyme solution and 3.0 ml of solutions of acceptors giving a final concentration as shown in the third column. Incubation time, 30 min. Digests were inactivated by 3.0 ml of 10% trichloroacetic acid solution and were analyzed for phenol and inorganic phosphate. In the case of the standard acceptor, 1,4-butanediol, the expected transfer product, 1,4-butanediol phosphate, was isolated in a yield of 35% from a large-scale experiment. The hydrolysis of this phosphate ester by prostatic acid phosphatase liberated approximately equimolar amounts of 1,4-butanediol and inorganic phosphate. 

The iotai proteolytic activity of pancreas powder is determined by comparing the quantity of peptides nonprecipitabie by a 556 m/V solution of trichloroacetic acid R released per minute from a substrate of casein solution with the quantity of such peptides released by pancreas powder (protease) UK from the same substrate in the same conditions. For the test suspension and the reference suspen-sion, prepare the suspension and carry out tiie dilution at (W-°C. 

Test C About 25 mg of the acid sample is dissolved in 15 mL of methylene chloride. The solution is examined in ultraviolet light at 365 nm to exhibit a strong greenish-yellow fluorescence. Carefully add 0.5 mL of a saturated solution of trichloroacetic acid dropwise and examine under ultraviolet light at 365 nm. The solution does not exhibit fluorescence. 

Rats weighing 200-300 g are starved for 24 hours, with free access to water before the experiment. They are treated orally or subcutaneously with the test compound 15 min prior to oral administration by gavage of 1.5 ml 0.07% phenol red in 2% car-boxymethylcellulose solution. 15 min later the animal is sacrificed and the stomach is immediately removed. The whole stomach including the stomach content is alkalized with 1 N NaOH and homogenized. The homogenate is filtered, and after precipitation of the protein with 10% trichloroacetic acid, centrifuged for 15 min at 3000 rpm. The concentration of phenol red in the supernatant is measured colorimetrically in a photometer at 546 nm. 

Haga et al. (1994) studied gastric emptying in mice. Male mice, weighing 18-22 g, had free access to food and water before the experiment. The test compounds were administered orally in 10 ml/kg 0.5 % methyl-cellulose solution. The mice were deprived of food and water and sacrificed 4 hours later by cervical dislocation. The stomachs were removed and opened. The contents of the stomach were mixed with 10% trichloroacetic acid, and centrifuged at 3000 rpm for 30 min. The weight of the sediment was taken as the food remaining in the stomach. 

Identification Place a drop of a saturated solution of sample into a micro test tube, and add a drop of a 0.5% solution of ammonium chloride and several milligrams of zinc powder. Cover the mouth of the tube with a disk of filter paper moistened with a solution of 5% p-dimethylaminobenzaldehyde and 20% trichloroacetic acid in hexane. Heat with a small flame for about 1 min. A pink to red-violet stain appears on the paper. 

Application and Principle This procedure is used to determine the proteolytic activity, expressed as hemoglobin units on the tyrosine basis (HUT), of preparations derived from Aspergillus oryzae var. and Aspergillus niger var., and it may be used to determine the activity of other proteases at pH 4.7. The test is based on the 30-min enzymatic hydrolysis of a hemoglobin substrate at pH 4.7 and 40°. Unhydrolyzed substrate is precipitated with trichloroacetic acid and removed by filtration. The quantity of solubilized hemoglobin in the filtrate is determined spectrophotometrically. 

It was found that most of the 2-deoxyribosylic compounds in a trichloroacetic acid extract of the bacteria are present chemically in such a combination that snake-venom treatment is required in order to make them microbiologically active. Furthermore, when the extract was tested without venom pretreatment but in the presence of thymidine, the growth-promoting effect of the 2-deoxyribosylic compounds was 10 times that displayed without thymidine and reached 60% of the activity obtained after venom treatment. The nature of the substances responsible for this effect has not yet been described. The acidic nature of the 2-deoxyri-bosylic compounds was shown by the fact that 98% of the mixture was adsorbed to a Dowex anion exchanger. In the eluted fractions, thymidine 5-phosphate, thymidine 5-pyrophosphate, and thsmiidine 5-triphosphoric acid were identified. From the major 2-deoxyribosylic fraction, thymidine rhamnosyl pyrophosphate (XIX) has been isolated. This substance was also identified in the thymidine-requiring mutant of Escherichia coli 15 T-. 

An attractive feature of this mechanism with respect to LAM is that it can be easily tested experimentally. On formation of a p3-S-adenosyl bond and termination of the reaction by acid denaturation of the protein, 5 -deoxy 5 -thioadenosine would be expected to be among the products formed. LAM was incubated with 5-[8- C]adenosyl-methionine under turnover conditions for various lengths of time, and then the reaction was terminated by the addition of trichloroacetic acid. Subsequent isolation and analysis by HPLC of the cleavage products of SAM showed that no radioactivity migrated with an authentic sample of 5 -deoxy 5 -thioadenosine. ... 

Trichloro-compounds—Fujiwara test. To 1 ml of urine add 1 ml of sodium hydroxide solution and 1 ml of pyridine, and heat in a boiling water-bath for 2 minutes. The development of a red colour in the pyridine layer indicates ingestion of a trichloro-compound. A blank urine sample and an authentic solution of trichloroacetic acid should be tested at tile same time, both blank and control solutions being treated in similar fashion to the sample, because contamination of the atmosphere with laboratory reagents may give positive results. 

Fig. 2. Gel filtration profile of I-labeled human prolactin, [ I]hPRL (VLS No. 3) io-dinated by the chloramine-T method and purified on a 1.5 x 30 cm Sephadex G-100 column, precoated with bovine serum albumin. Elution solvent was 10 mM phosphate buffer, pH 7.5, containing 0.15 M NaCl and 1 10,000 Merthiolate. The labeled hormone was purified just prior to use. The talc-resin-trichloroacetic acid (TCA) test results showed that peak III material was suitable for use in radioimmunoassay (Tower et al. ).

Talc-Resin-Trichloroacetic Acid (TCA) Test Results for -I-Labeled Hormones Prepared by the Glucose Oxidase-Lactoperoxidase (GO-LPO) Iodination Method ... 

---