Radioactive supernatant

Carefully discard the radioactive supernatant by inverting the plate over a sink, designated for aqueous radioactive waste, and then wash the wells three times with PBST. 

After rocking for 1 h at room temperature, open the bags, dispose of the radioactive supernatant safely, and then wash the blots four times with PBST, and dry at 37°C... 

The stabihzation of a range of contaminants, including Cr , in Ceramicrete was demonstrated by Wagh et al. [60] with two liquid waste streams that simulated radioactive supernatant and sludge from Hanford tanks within the DOE complex. These waste streams... 

Add 50 pL of 2 I-labeled second antibody (10 cpm/50 pL in PBS-Mar-vel) to each well and incubate for a further 1 h at ambient temperature. Carefully discard the radioactive supernatant by inverting the plate over a sink, designated for aqueous radioactive waste, then wash the wells three times with PBST. 

Incubation is often performed in small plastic tubes, which can be centrifuged directly to form, within seconds, a cell or membrane pellet. The supernatant can then be either tipped off or removed by suction. The radioactivity of the supernatant can be measured to determine the free ligand concentration. Any supernatant remaining on the surface of the pellet or tube can be reduced by... 

Fluorescence Radioactivity MS Complete Release Blank A nalyse supernatant or gel fraction ... 

To determine the optimal reaction time for a particular radioiodination, 5 pi aliquots of the reaction medium can be removed every 30 seconds, diluted 1 20,000 with 20 mM Tris, 1 mM ethylenediaminetetraacetic acid (EDTA), pH 7.4, containing 0.5 mg/ml BSA as a carrier protein. Finally, precipitate a small amount of the diluted aliquot with trichloroacetic acid (TCA, 60 percent), centrifuge to recover the pellet, wash the pellet once with TCA, and measure the amount of radioactivity in the pellet and supernatant using a gamma counter. The reaction period representing optimal radiolabel incorporation should be used for subsequent radioiodinations. 

Following immersion of the glass slides in a 1.0 (w/v) BSA-BSA solution to a depth of 2.1 cm for 30 min at 21°C, the slides were thoroughly rinsed in PBS by dilution/displacement. The slides were then completely immersed in PBS, where they were kept for different lengths of time, i.e., for 1, 2, 4, and 16 hrs. Thereafter, the slides were removed and air-dried and placed on X-ray film between Lanex Intensifying Screens as described above. The supernatants from these diffusion experiments were then concentrated 10 times by evaporation in order to establish their radioactive content. 

Another cultured cell line of Catharanthus roseus (EU4A), which does not produce detectable amounts of vinblastine and other bisindole alkaloids, was also examined for its ability to transform 78 (183). Cell-free extracts of the culture line were prepared, and the 35,000 X g supernatant solution was used. Incubations with 2r-tritioanhydiovinblastine yielded a mixture from which radioactive vinblastine (52) was isolated. The labeled vinblastine was reisolated after unlabeled carrier was added and rigorously purified by successive thin-layer chromatography, reversed-phase HPLC, and crystallization to constant specific activity. Boiled extracts could not produce labeled 52, thus supporting the involvement of enzymes in the conversion process. 

Figure 11.9 Schematic view of the experimental strategy for carrying out poly(Phe) synthesis in POPC liposomes, (i) Freeze-thaw (x 7) solution containing t-RNAP , poly(U), Phe, ATP, GTP, Mg(OAc)2, NH4CI, spermine, spermidine, phos-phoenolpyruvate. (ii) Soution containing pyruvate kinase, 100 000 g supernatant enzymes, 308 and SOS ribosomal subunits, (iii) 1. Free-thaw (x3) 2. Brief extrusion 3. Addition of EDTA (final concentration = 35 mM. (iv) Withdrawl of aliquots at indicated time and cold TCA precipitation. Analysis of the radioactivity remaining on the glass filter by p-scintillation counting. (Modified from Oberholzer et al, 1999.)...

The classic example of a radiometric titration concerns the titration of some unknown material with a radioactive reagent to give a radioactive precipitate. In this case, the activity of the supernatant or the precipitate can be followed as a function of titrant volume, as shown in Figure 4.10. In this type of titrations, the tracer must have a long half-life and must emit high-energy 3 or y rays so as to minimize self-absorption corrections (assuming, as is common practice, that the supernatant or precipitate is removed from the system and counted in an external sample counter after the addition of each volume of titrant). 

A radioactive tracer method was developed to quantitatively measure the adsorption of high molecular wt compds on the surfaces of powdered expls. Expts were conducted by allowing a pre-weighed amt of powdered expl to equilibrate with a fixed volume of radioactive adsorbate in an appropriate solvent. The expl must be either insoluble or of very low solubility in the solvent used. At equilibrium, an aliquot of supernatant soln is removed and its radioactivity is measured. The loss in radioactivity is a measure of the amt of adsorbate taken up by the expl. By varying the concn of adsorbate in the soln, an adsorption isotherm can be constructed relating amount adsorbed with solution concn... 

The mixture was then treated with 5 ml of alkaline hydroxyl-amine reagent ( 20 ml hydroxylamine hydrochloride titrated to pH 13 with 3.5M NaOH ) for 5 min and the protein precipitated with 5% trichloroacetic acid. After centrifuging ( 5000 g ) for 5 min the supernatant was carefully decanted and the precipitate washed twice with 10-ml aliquots of absolute ethanol. The material was then dissolved in 1 ml, of 0.2M NaOH, mixed with 10 ml of Insta-gel scintillator ( Packard Instrument (Pty) Ltd.), and the radioactivity counted in a Packard Tri Carb Liquid Scintillation Spectrometer. 

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