Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Scintillation Counting”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1977

Measurement of 'unscheduled' DNA synthesis in HeLa cells by liquid scintillation counting after carcinogen treatment.

HeLa cells, conditioned in an arginine-deficient medium to reduce DNA S-phase synthesis, were treated with one of four ultimate carcinogens (MNNG, BrMBA, N-acetoxy AAF and EMS) and one precarcinogen, AFB1. All treated cells preferentially incorporated [3H] thymidine as a result of DNA repair monitored by liquid scintillation counting of the extracted DNA. The cells showed some capacity to activate AFB1, but repair synthesis was much increased if a rat liver mixed function oxidase preparation was also present. At equimolar concentrations the various carcinogens stimulated different amounts of DNA repair; this variation was not proportional to the carcinogenic potency of the chemicals tested. Reasons for this are discussed as is the use of this technique as a screen for chemical carcinogens.

Acetoxyacetylaminofluorene↗
PubMed1969

Quantitative studies on enzymes in structures in striated muscles by labeled inhibitor methods. II. Confirmation of radioautographic measurement by liquid-scintillation counting.

Fragments of mouse diaphragm and sternomastoid muscles were incubated in diisopropyl-fluorophosphate (DFP)-(3)H in conditions known to saturate all the available DFP-sensitive reaction sites. After being extensively washed, the enzyme acetylcholinesterase (AChase) was specifically reactivated by treatment with pyridine-2-aldoxime methiodide (2-PAM). The radioactive DP-groups released into solution by 2-PAM were measured by liquid scintillation counting, and related to the known number of motor endplates present. Considerable difficulty was encountered in reducing the excess, adsorbed radioactivity to acceptable levels: long washing routines, extraction with organic solvents, and removing excess muscle fiber by microdissection were necessary. Six experiments gave a mean value of 2.4 x 10(7)molecules AChase per sternomastoid endplate, in reasonable agreement with the previously reported measurements by radioautography.

Acetylcholinesterase↗
PubMed1987

[Scintillation counting as an in vitro method for assessing the pretherapeutic effectiveness of planned tumor chemotherapy in patients with ovarian cancer].

In vitro testing methods to obtain information about the proliferation of the tumour, which we want to treat by chemotherapy, have been vindicated by the biological individuality of ovarian cancer cells. The determination of the incorporation rate of 3H-thymidine in cells of ovarian cancer by scintillation counting may be recommended as a prognostic factor in regard of success of chemotherapy in patients with this disease.

Antineoplastic Agents↗
PubMed1988

Improved method for the determination of the cortisol production rate using high-performance liquid chromatography and liquid scintillation counting.

Two new methods for the determination of the cortisol production rate using reversed-phase high-performance liquid chromatography are described. One uses ultraviolet detection at 205 nm, the other on-line post-column derivatization with benzamidine, followed by fluorimetric detection. The specific activity of tetrahydrocortisol and tetrahydrocortisone in urine from patients who had received tritium-labelled cortisol was determined by the indicated methods, followed by fraction collection and liquid scintillation counting. The post-column reaction detection procedure was superior to ultraviolet detection, both in selectivity and analysis time. Intra- and inter-assay variance of the post-column reaction detection procedure were 3.7 and 4.7%, respectively. A good correlation (r = 0.99) was obtained between values determined by this procedure and by a thin-layer chromatographic procedure.

Chromatography, High Pressure Liquid↗
PubMed2000

MAC3: an electronic module for the processing of pulses delivered by a three photomultiplier liquid scintillation counting system

In the field of radioactivity measurement, there is a constant need for high quality electronic modules such as ADCs, amplifiers, high voltage generators, dead-time modules, etc. and sometime there is a need for a specialized module not available on the market. The purpose of the module presented here, called MAC3 (module d'acquisition de coincidences triples), is to process the pulses delivered by the three detectors (photomultipliers) used in our liquid scintillation counting system. The dead-time generated by this module is of the extendible type and the dead-time corrections are made according to the live-time method. This module, which has been developed and tested at LPRI, can replace the complex interconnection of several independent and costly modules. The philosophy governing the choice and the implementation of this type of dead-time as well as the system used for the dead-time corrections is presented. The electronic scheme and the performances are also presented. This module is available in the NIM standard.

Journal Article↗
PubMed2004

Activity standardization by liquid scintillation counting and half-life measurements of 90Y.

Radioactive 90Y was standardized by means of 4piBeta liquid scintillation efficiency tracing with a two-phototube counting system. The efficiencies of 90Y and the tracer 3H are related by the CIEMAT/NIST method. The dependence of the calculated efficiency on various shape factors and the importance of accurately measuring the radionuclide impurity of 90Sr are discussed. The half-life of 90Y was measured with improved accuracy by means of a liquid scintillation counting and a 4pi ionization chamber measuring system, and an average value T1/2 = 64.053(20) h was found.

Half-Life↗
PubMed2005

Analysis of low level radioactive metabolites in biological fluids using high-performance liquid chromatography with microplate scintillation counting: method validation and application.

TopCount, a microplate scintillation counter (MSC), has been recently employed as an off-line liquid radiochromatographic detector for radioactive metabolite profile analysis. The present study was undertaken to validate TopCount for metabolite profiling with respect to sensitivity, accuracy, precision and radioactivity recovery. Matrix effects of various human samples on TopCount performance and capability of MSC for volatile metabolite analysis were also investigated. TopCount had a limit of detection (LOD) of 5 DPM and a limit of quantification (LOQ) of 15 DPM for [(14)C]-labeled compounds at a 10min counting time. It was two-fold more sensitive than a liquid scintillation counter (LSC), and 50-100-fold more sensitive than a radioactivity flow detector (RFD). TopCount had comparable accuracy and precision to RFD, and comparable precision to LSC for determining relative abundance of metabolites. Human liver microsome incubation (up to 1 mL), plasma (up to 1 mL), urine (up to 2 mL) and feces (up to 50mg) had no significant quenching effects on TopCount performance. Benzoic acid, a volatile metabolite, was detected by TopCount, but not by Microbeta counter after microplates were dried under vacuum. Radioactivity recovery in HPLC-MSC analysis was reliably determined using an LSC-based method. Examples of using HPLC-MSC for analysis of low levels of radioactive metabolites are presented, including determination of plasma metabolite profile, in vitro reactive metabolites trapped by [(3)H]glutathione, and metabolite concentrations in an enzyme kinetic experiment. The data from this study strongly suggest that HPLC in combination with TopCount is a viable alternative analytical tool for detection and quantification of low levels of radioactive metabolites in biological fluids.

Animals↗