Low background scintillation counting.

Hahnemann University, Philadelphia, PA 19102.
BioTechniques (Impact Factor: 2.95). 04/1989; 7(3):232-7.
Source: PubMed


Counting radioactive samples with Beckman Instrument's Ready Caps, using a restricted energy window, LL-UL = 400-1000, resulted in machine backgrounds of under 2 cpm and efficiencies of counting relative to liquid scintillation cocktails (LSC) of 51%, 65%, 57%, 62%, and 1% for 32P, 125I, 14C, 35S and 3H, respectively. Signal-to-noise ratios from a quantitative molecular hybridization technique were increased 8-10 fold. There may be a general application for this product in experiments yielding low amounts of radioactivity in liquid samples.

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    ABSTRACT: Peripheral blood mononuclear cells from HIV-1-infected persons were mixed with 5 M guanidine thiocyanate, and HIV-1-specific probes were hybridized with target RNA directly in the lysate. No RNA purification was needed. Hybrids were purified by repeated capture on superparamagnetic beads coated with oligo(dT) in a device-assisted format, a procedure termed "reversible target capture." Blood mononuclear cells from 70 ARC and AIDS patients were examined and found to have an average of 1.8 x 10(5) molecules of HIV-1 RNA per 2 x 10(6) cells.
    No preview · Article · Jan 1989 · Journal of Clinical Laboratory Analysis
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    ABSTRACT: For increased clinical applications of nucleic acid probes to gene diagnosis, current procedures must be modified to become more amenable to the rapid processing of many samples with as few manipulations as possible. Here we summarize progress in the development of a strategy for performing molecular hybridization directly in lysate of biological samples dissolved in solutions containing the chaotropic agent, guanidine thiocyanate. Hybrids are purified by a process referred to as "reversible target capture," in which specific nucleic acid sequences are rapidly purified from crude lysate. We illustrate the use of this strategy to assay HIV-1 RNA and to rapidly purify HIV-1 RNA before enzymatic amplification by the polymerase chain reaction method.
    Preview · Article · Oct 1989 · Clinical Chemistry