PubMed · 2648108
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J E Sisken. 1989. Fluorescent standards.. https://pubmed.ncbi.nlm.nih.gov/2648108/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Europium-154 can be obtained as a by-product from the large-scale production of Samarium-153 and possesses attractive features (t1/2 8.592 yr; Egamma 0.12-1.6 MeV) for use as a reference source similar to 152Eu (t1/2 13.516 yr; Egamma 0.12-1.4 MeV), which is the gold standard for calibration in gamma ray spectrometry. Thermal neutron irradiation of 5mg of 98% enriched 153Sm2O3 target in the reactor led to approximately 200 GBq 153Sm and 1.26 MBq 154Eu. A typical batch control sample of 153SmCl3 solution and final radiopharmaceutical product formulation of 153Sm-phosphonate (153Sm-EDTMP) pooled together contained about 20% of total yield, requiring post decay disposal of 153Sm as radioactive waste. Such spent solutions pooled on quarterly basis led to availing 756 kBq of 154Eu. The radioactivity content and radionuclide purity (approximately 82%) of the recovered 154Eu sample were envisaged as adequate to prepare reference sources for calibration of gamma ray spectrometers. At present, one batch of 153Sm is handled per month at our institution, with the possibility for weekly processing in future. Access to approximately 3.5 MBq of 154Eu on quarterly basis is envisaged, apart from obviating the need for instituting steps to tackle disposal of the long-lived 154Eu in the spent solution. Up to 60-120 units of 20-100 kBq of 154Eu reference sources per year could thus be available by the proposed strategy.
Conventional methods for point mutation detection are usually multi-stage, laborious, and need to use radioactive isotopes or other hazardous materials, and the assay results are often semi-quantitative. In this work, a protocol for quantitative detection of H-ras point mutation was developed. Electrochemiluminescence (ECL) assay was coupled with restriction endonuclease digestion directly from PCR products. Only the wild-type amplicon containing the endonuclease's recognition site can be cut off, and thus cannot be detected by ECL assay. Using the PCR-ECL method, 30 bladder cancer samples were analyzed for possible point mutation at codon 12 of H-ras oncogene. The results show that the detection limit for H-ras amplicon is 100 fmol and the linear range is more than three orders of magnitude. The point mutation was found in 14 (46.7%) out of 30 bladder cancer samples. The experiment results demonstrate that the PCR-ECL method is a feasible quantitative approach for point mutation detection due to its safety, high sensitivity, and simplicity.
A fully validated procedure for the simultaneous determination of morphine (MOR), morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G), 6-acetylmorphine (6AM), codeine (COD), codeine-6-glucuronide (C6G), acetylcodeine (AC), noscapine (NOS) and papaverine (PAP) based on liquid chromatography followed by electrospray mass spectrometry applying multiple reaction monitoring (LC-ESI-MS/MS) in urine samples is described. The extraction was carried out on a Zymark Rapid Trace Workstation using C18 solid-phase extraction cartridges. The separation was performed in 19 min on an Agilent 1100 HPLC system, using a Phenomenex C18 AQUA column (4 microm, 150 mm x 2 mm), which is coupled with an Applied Biosystems API 2000 mass spectrometer. Deuterated analogues were used as internal standards. The limits of detection were in the range of 0.1 ng/ml (PAP) to 7.4 ng/ml (M6G), the coefficients of correlation were higher than 0.996, the precisions ranged from 3% to 12% and the absolute recoveries were between 45% (M3G) and 98% (MOR). Analyses of samples from patients of a heroin prescription program demonstrated the usefulness of the procedure for the analytical differentiation between prescribed synthetic heroin (diamorphine) use and non-prescription heroin abuse on the basis of urine analysis. After the ingestion of pharmaceutical heroin only general markers for heroin use were detected, which are MOR, M3G, M6G and 6AM, respectively. When illicit heroin was abused, additionally to further general markers (COD, C6G) specific markers for non-prescription heroin abuse (AC, NOS, PAP) were found. However, it must be kept in mind that only AC may be regarded as absolute specific marker of non-prescription heroin, because all other compounds may appear in urine after ingestion of opiate alkaloids containing medicines or foods (e.g. poppy seeds). Therefore, patients of a heroin prescription program should be advised not to ingest such products.