PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ISOTOPES, RADIOACTIVE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 145 records · Page 8Linked to original sources
PubMed1983

[Use of radioactive isotopes in clinical hematology].

Principles underlying the use of radioactive isotopes for diagnostic, prognostic, and therapeutic purposes in human biology are briefly discussed, and the possibilities of the employ of isotopic techniques in general illustrated by the results obtained in human hematology.

Blood Cells↗
PubMed1990

Versatile stable isotope technique for the measurement of amino acids and keto acids: comparison with radioactive isotope and its use in measuring in vivo disposal rates.

Tracer methods using both carbon-13 and -14 have been utilized for determination of ovine fetal amino acid disposal and the results compared in seven animals. We infused [1-13C]leucine simultaneously with [1-14C]leucine into the fetal circulation of pregnant sheep chronically catheterized during late gestation. Radioactive and stable isotope enrichments of leucine (Leu) and stable isotope enrichments of ketoisocaproic acid (KIC) in the umbilical artery and vein and the maternal artery and uterine vein were measured. Stable isotope enrichments and concentrations of both Leu and KIC were determined from a single 0.2-ml sample by the use of internal standards and electron ionization GC/MS analysis after a simple isolation and derivatization procedure. The KIC/Leu enrichment ratio was measured for the first time in fetal arterial plasma and was 0.66 +/- 0.05 (SE). Fetal leucine disposal rate was 9.0 +/- 0.5 (SE) micron/min/kg. Disposal rates determined by stable isotopes were not different from those determined by radioactive isotopes. The GC/MS stable isotope method provided higher precision in both leucine concentration and enrichment measurements and has been shown to be a general method for the determination of concentration and isotopic enrichment of other amino acids and their corresponding keto acids. Furthermore, this method is ideally suited to clinical studies where large numbers of samples of rather small volume can easily be studied with a short turnaround time.

Amino Acids↗
PubMed2002

Marine biogenic minerals hold clues about changes in ocean chemistry and climate: some important lessons learned from studies of stable and radioactive isotopes of Be and Al.

The elements Be and Al exhibit very short residence time in ocean waters, and therefore serve as useful tracers for the study of biogeochemical processes in seawater. A unique feature of these tracers is that nuclear interactions of cosmic rays in the atmosphere produce appreciable amounts of two radioactive isotopes, 10Be (with a half-life of 1.5 my) and 26Al (with a half-life of 0.7 my), which are introduced in the hydrosphere, cryosphere, and lithosphere via precipitation. Thus, these elements are labeled by their respective radioactive isotopes, which help quantitative tagging of their biogeochemical cycles. Finally, as we report here, several marine organisms incorporate them in their skeletal shells in certain fixed proportions to their concentrations in the seawater, so that it seems possible to study changes in the ocean chemistry and climate over the past several million years. We summarize here the recent discovery by Dong et al. of significant enrichments of intrinsic Be and Al in marine foraminiferal calcite and coral aragonite, and of Al in opal (radiolarians) and aragonite (corals), which should make it possible to determine 10Be/Be and 26Al/Al in oceans in the past. We also summarize their measured 10Be/9Be in foraminiferal calcite in Pacific Ocean cores, which reveal that the concentrations and ratios of the stable and cosmogenic isotopes of Be and Al have varied significantly in the past 30 ky. The implications of these results are discussed.

Aluminum↗
PubMed2004

Atmospheric xenon radioactive isotope monitoring.

The Comprehensive Nuclear Test Ban Treaty (CTBT) organisation is implementing a world-wide monitoring network in order to check that the State Signatories comply with the treaty. One of the monitoring facilities consists of an atmospheric noble gas monitoring equipment. According to the requirements annexed in the treaty, the French Atomic Energy Commission (CEA) developed a device, called SPALAX, which automatically extracts xenon from ambient air and makes in situ measurements of the activities of four xenon radioisotopes (131mXe, 133mXe, 133Xe, 135Xe). The originality of this device is noticeable essentially in the gas sample processing method: thanks to the coupling of a gas permeator and of a noble gas specific adsorbent, it can selectively extract and concentrate xenon to more than 3 x 10 E6. This process is carried out continuously without cryogenic cooling, without any regeneration time. The detection of the xenon radioactive isotopes is done automatically by high spectral resolution gamma spectrometry, a robust technology well-suited for on-field instrumentation. In the year 2000, a prototype was involved in an international evaluation exercise directed by the CTBT organisation (CTBTO). This exercise demonstrated that the SPALAX equipment perfectly met the requirements of the CTBTO for such systems. On the basis of the continuous 24-h resolution record of the atmospheric xenon radioactive isotopes concentrations, the SPALAX system also demonstrated that ambient levels of 133Xe can fluctuate quickly from less than the detection limit to over 40 x 10(-3) Bq m(-3). In order to build an industrial version of this equipment, the CEA entered into a partnership with a French engineering company (S.F.I., Marseille, France), which is now able to produce an industrial version of SPALAX, i.e. more compact and more efficient than the prototypes. The 133Xe minimum detectable concentration is 0.15 x 10(-3) Bq m(-3) air per 24 h sampling cycle.

Air Pollutants, Radioactive↗
PubMedDate not supplied

The application of a new method of limb blood flow measurement using a radioactive isotope and a gamma camera.

To evaluate a new method for limb blood flow measurement using a radioactive isotope and a gamma camera, blood flow measurements have ben made on 108 patients with peripheral vascular disease. Thirty-six patients had ischaemic rest pain, of whom two had previously undergone unilateral amputation. Five had bilateral symptoms, giving 29 asymptomatic limbs and 41 limbs with critical ischaemia. In 72 patients with intermittent claudication a series of exercise tests were attempted, in 33 these were unsatisfactory; 13 patients had a greater than 20% variability in the maximum walking distance between four tests and in 20 walking distance was limited by factors other than claudication. In these 33 patients the limb blood flow to the symptomatic leg was 3.95 (1.36-11.08) ml/100 ml of tissue/minute. This is not significantly different from the limb blood flow to the symptomatic leg of the 39 patients who satisfactorily completed four exercise tests, 3.75 (1.08-8.25) ml/100 ml of tissue/minute. In these 39 patients the mean pain-free walking distance was 40 metres and the mean maximum walking distance was 63 metres. The limb blood flow to the 41 symptomatic limbs of 36 patients with rest pain was 1.90 (0.90-4.49) ml/100 ml of tissue/minute, which is significantly less than that obtained in claudicants. There was a wide range of blood flow values found in the asymptomatic limbs of all the patients and in many cases the flow was markedly reduced from normal. This method of limb blood flow measurement is accurate and reproducible and may be recommended for assessment of peripheral vascular disease.

Adult↗