Investigation of select radionuclides stability in urine under various conditions for liquid scintillation counting (LSC).

Liquid Scintillation Counting (LSC) gross alpha/beta screening is a valuable tool for providing rapid laboratory response for the analysis of human clinical urine samples during a large-scale radiation incident event. Verification of method performance, as required for clinical laboratory testing, is accomplished by the evaluation of routine, periodic measurements of radioactive spiked samples for quality control, performance testing, and accuracy checks. Radionuclide stability of alpha and beta emitters in urine for LSC analysis is an important consideration. The purpose of this work is to demonstrate optimal preparations and storage conditions of samples used for method verification.

Alpha and beta spillover in liquid scintillation counting analysis of urine samples.

Rapid detection and quantification of gross alpha/beta-emitting radionuclides by liquid scintillation counting (LSC) is vital in guiding response to a nuclear or radiological incidents. Liquid scintillation counters use signal pulse shape to discriminate alpha and beta events in samples but require precise optimization to minimize the spillover, or misclassification, of those events. In this study, samples at varying activity levels were analyzed by LSC to determine the effect of activity level, emitter type, and sample matrix on spillover. Analysis proved a matrix effect and a direct correlation of activity level on spillover percentage for both alpha and beta emitting-nuclides.

Universal use of alpha/beta mode in liquid scintillation counting analysis for both alpha/beta and single nuclide determination.

Nuclear industry advancements and growing concerns about environmental contamination and terrorist activity have increased interest in quantifying radioisotopes in environmental and human samples. Increased presence in the environment, ease of entry into the food chain, nuclear medicine applications, and the possibility of radiological terrorism incidents can lead to human intake of these radionuclides [1,2]. A universal method to screen for and quantify individual radionuclides as well as both levels of alpha and beta emitters would address these concerns.

The effect of Sr resin cartridge age on stable Sr recovery methods used in Sr-90 analysis.

Radioactive strontium is a nuclear fission decay product found in industrial products and nuclear waste and is released during nuclear accidents. Current urine radiostrontium separation methods often are based on the use of Sr resin columns or cartridges (Eichrom Technologies). Most of these analytical methods use stable Sr as a tracer, with subsequent Sr recovery. The gravimetric recovery method requires 120 times more stable Sr than does the inductively coupled plasma mass spectrometry method described here. This difference can affect cartridge performance especially with aging cartridges.

Urine gross alpha/beta bioassay method development using liquid scintillation counting techniques.

In the case of a radiological or nuclear incident, valuable information could be obtained in a timely manner by using Liquid Scintillation Counting (LSC) technique through fast screening of urine samples from potentially contaminated persons. This work describes the optimization of LSC parameters on PerkinElmer (PE) Tri-Carb and Quantulus GCT series instruments to develop a rapid method for screening urine in an emergency response situation.

Urine strontium-90 (Sr-90) manual and automated pre-analytical separation followed by liquid scintillation counting.

Responding to a radiological or nuclear incident may require assessing tens to hundreds of thousands of people for possible radionuclide contamination. The measurement of radioactive Sr is important because of its impact on people's health. The existing analytical method for urine Sr-90 analysis using crown ethers is laborious and involves possible exposure to concentrated acids; therefore, this work is devoted to the development of the automated Sr-90 separation process, which became possible with the prepFast pre-analytical system (Elemental Scientific, Inc).

Limit of detection comparison on urine gross alpha/beta, H-3, and P-32 analysis between different liquid scintillation counters.

As part of the Centers for Disease Control and Prevention's post-radiological/nuclear incident response mission, we developed rapid bioassay analytical methods to assess possible human exposure to radionuclides and internal contamination. Liquid scintillation counting (LSC) is a valuable analytical tool for the rapid detection and quantification of gross alpha/beta-emitting radionuclides in urine samples. A key characteristic of this type of bioassay method is its detection sensitivity for the priority threat radionuclides. We evaluated the limit of detection of selected LSC instruments to determine which instrument can be used when low-dose measurement is important.

The effect of quench agent on urine bioassay for various radionuclides using Quantulus™1220 and Tri-Carb™3110.

Following a radiological or nuclear incident, the National Response Plan has given the Department of Health and Human Services / Centers for Disease Control and Prevention the responsibility for assessing population's contamination with radionuclides. In the public health response to the incident, valuable information could be obtained in a timely and accurate manner by using liquid scintillation counting techniques to determine who has been contaminated above background for alpha and beta emitting radionuclides. The calibration plays a major role in this process therefore, knowing the effect of quench agents on calibration is essential.

Synthetic long-chain alkyl maltosides and alkyl sucrose esters as enhancers of nasal insulin absorption.

A series of new glycosides with extended alkyl side-chains (C(13-16)) linked to maltose or sucrose were synthesized and tested for their efficacy in enhancing nasal insulin absorption in anesthetized rats. The new reagents were compared to previously tested alkylglycosides with shorter alkyl side chains (C(8-12)). Dose-response studies revealed that within the family of alkylmaltoside derivatives, (C(8-16)), maximal increases in insulin absorption took place when tetradecylmaltoside (C(14)) was added to the formulation. Pentadecylmaltoside (C(15)) and hexadecylmaltoside (C(16)) were less potent at increasing insulin absorption, although both reagents achieved maximal effects when used at higher concentrations. Within the family of alkanoylsucrose derivatives, tridecanoylsucrose (C(13)) and tetradecanoylsucrose (C(14)) were most potent at increasing insulin absorption. Cross-comparisons between alkylmaltoses and alkanoylsucroses showed that the alkyl chain length had a greater impact than the glycoside moiety in determining the potency of a potential insulin-absorption enhancing agent. When tetradecylmaltoside was applied to the nasal mucosa 15 min before insulin was applied, the enhanced insulin absorption was still observed.

Distribution, metabolism, and excretion of a novel surface-active agent, purified poloxamer 188, in rats, dogs, and humans.

Purified poloxamer 188 (PP188) is a nonionic, block copolymer surfactant with hemorheologic, antithrombotic, and anti-adhesive properties. PP188 is being studied in phase III clinical trials in sickle cell disease and has been found to be well tolerated and has demonstrated benefit in ameliorating the effects of acute painful vasoocclusive crisis. The disposition of PP188 was studied in rats, dogs, and humans to establish a basis for understanding the safety parameters in support of clinical trials. PP188 was primarily distributed in extracellular water with little or no uptake by red blood cells, and had its highest concentrations in highly perfused tissues such as the kidney, liver, spleen, lymph nodes, and gastrointestinal tract. PP188 had no apparent effect on P450 isozymes in vitro. Metabolism was limited (< 5% of dose) with a higher molecular weight copolymer being the only other material detected in plasma or urine. Renal clearance was the controlling route of clearance for PP188 from the body. The 48-h intravenous infusion doses of PP188 were cleared in all species by approximately 1 week after the cessation of dose administration. PP188's disposition is a model for other nonionic block copolymers with similar physical and chemical properties.