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Radioisotopes in Biology and Medicine
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
This technique has been used extensively for the analysis of trace metal concentrations in various organs following X-irradiation, drug, or hormone treatment. The basic principle of neutron activation analysis is simple. The trace metals under investigation are made radioactive by bombarding the dry samples of liver, plasma, or spinal fluid with slow neutrons. During neutron irradiation, the stable trace metals, together with other elements, capture neutrons and become radioactive. By using a radiation detector, the amount of trace metal can be quantified. However, in organ samples, other elements (such as sodium, potassium, and chlorine, which have very high cross-sections for neutron capture) also become radioactive; this makes it impossible to quantify the radioactivity of a trace metal by single-channel analysis. Two techniques have been used to overcome the above difficulty. Use of multichannel analyzer: The multichannel analyzer separates the photopeak of radioisotopes of different energy. By stripping off the energy contribution from other radioisotopes with the help of a computer, one can get a single photopeak of the radioactive trace metal under investigation.Chemical separation of activated trace metals: Activated samples are digested in acid and mixed with a nonradioactive trace metal; the radioactive trace metal is precipitated chemically and then counted by a single-channel analyzer.
Total Body Neutron Activation
Published in Stanton H. Cohn, Non-Invasive Measurements of Bone Mass and Their Clinical Application, 2020
Interfering reactions occur in activation analysis when elements other than those being analyzed become radioactive and emit photons in the energy region being studied. Reaction interferences of Type 1 are those in which the primary reaction produces the same radionuclide as that from the element being analyzed. Reaction interferences of Type 2 involve secondary reactions produced in the matrix by particles other than those of the primary beams.
Principles and Problems of Cadmium Analysis
Published in Lars Friberg, Tord Kjellström, Carl-Gustaf Elinder, Gunnar F. Nordberg, Cadmium and Health: A Toxicological and Epidemiological Appraisal, 2019
Carl-Gustaf Elinder, Birger Lind
Cadmium has a number of stable isotopes. Neutron irradiation yields new radioactive cadmium isotopes. These can be quantitatively measured on the basis of their specific energy and half-life. A procedure for determination of cadmium in human liver samples by neutron activation analysis (NAA) is given by, e.g., Halvorsen and Steinnes.25 Usually the irradiated sample is digested before radioactivity is measured. Occasionally, it becomes necessary to concentrate cadmium by chemical methods and to separate the cadmium ions from other isotopes, which have an energy spectrum that overlaps the cadmium spectrum, before measurement can be carried out. Nonradioactive cadmium is normally added after irradiation. This procedure enables measurement of the recovery after digestion and the various concentration steps. For neutron activation analysis in most biological materials, sensitivity is high and the detection limit is low, in the order of 1 μg Cd per kilogram or 0.1 to 1 μg Cd per liter in a solution which is very close to the normal values (Chapter 5). However, the method is not normally used for screening programs due to the prohibitive costs entailed in the irradiation of the samples in a reactor. Neutron activation analysis is often used as a reference method to test the accuracy of other methods. Activation analysis is not the ideal method for liquid samples such as blood and urine. Ampoules filled with liquid samples may explode, due to the formation of gases in the sample during irradiation in the reactor.
Quantification of platelet function - a comparative study of venous and arterial blood using a novel flow cytometry protocol
Published in Platelets, 2022
Mattias Törnudd, Mohamad Rodwan Al Ghraoui, Sofia Wahlgren, Erik Björkman, Sören Berg, John-Peder Escobar Kvitting, Joakim Alfredsson, Sofia Ramström
Preparations were also made for the platelet activation analysis. The frozen agonists were thawed at 37°C (water bath) and thereafter aliquoted into flow cytometry tubes. Furthermore, antibody master mixes were added to their addressed tubes. Each tube in the series for the platelet activation analysis had a final volume of 36 µL, of which 3 µL was whole blood from the hirudin tube. The first four test tubes were control tubes without platelet agonists. The first two contained isotype master mix. Buffers used for these tubes were HEPES-EDTA to the first (serving as negative control for PAC-1) and HEPES buffer without calcium in the second (serving as negative control for P-selectin, LAMP-1 and annexin V). For all other tubes, HEPES-Ca2+ was used as buffer and the antibody master mix was added. In the third tube, CCCP, with final concentration 100 µM, was added immediately before the addition of blood to serve as a positive control to DilC1(5). The fourth tube served as a resting control to detect potential pre-activation of the blood samples. Tube 5–12 contained agonist solutions and antibody master mix.
How Has Electromyography Been Used to Assess Reaching in Infants? A Systematic Review
Published in Journal of Motor Behavior, 2021
Mariana Vieira da Fonseca, Ana Letícia de Souza Oliveira, Roberta de Matos Figueiredo, Rosana Tannús Freitas Lima, Aline Martins de Toledo
Out et al. (1998) conducted a study with infants of three, four and five months of age to investigate whether the lower frequency of reaching in the supine position, compared to the sitting position, would be related to specific muscular aspects. The authors hypothesized that in supine position, there would be insufficient muscle torque at the beginning of reaching or insufficient muscle control due to a mechanically unstable arm position. However, they found that muscle torque at the beginning of reaching in the sitting position was as high as during the supine position. In addition, there was a greater biceps-triceps coactivation in the seated position compared with the supine position. Likewise, Bakker et al. (2010) investigated infants of four and six months of age and also evaluated biceps-triceps coactivation in the sitting and supine position. Contrasting with Out et al. (1998), Bakker and colleagues showed that biceps-triceps coactivation was highly variable, with no difference between positions. However, there were differences between these studies in the co-activation analysis. While Bakker et al. (2010) restricted the analysis to the biceps and triceps co-activation in movements in which the biceps was the prime mover, Out et al. (1998) did not control the prime mover action as a criterion for co-activation analyzes.
Biomarkers of disease in human nails: a comprehensive review
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Sarahi Jaramillo Ortiz, Michael Howsam, Elisabeth H. van Aken, Joris R. Delanghe, Eric Boulanger, Frédéric J. Tessier
Other elements have also been studied in nails, enabled in part by the more widespread use in recent decades of multi-element analytical techniques such as instrumental neutron activation analysis (INAA) or inductively-coupled plasma (ICP) with optical emission spectroscopy (OES) or MS detection. A study by Garland et al. [84] used INAA to establish the principle whereby ungual concentrations of elements as risk or prognostic biomarkers of cancer (and other diseases) may be obtained from a single measurement. They studied 16 elements in paired toenail samples taken 6 years apart to determine the validity of a single measurement to assess exposure, reporting that a single measure of toenail Se and arsenic (As) was reflective of dietary intake. Other elements in toenails such as mercury (Hg) and zinc (Zn) were also reported as indicative of exposure, but copper (Cu), titanium (Ti), and chrome (Cr) were less reliable. Interestingly, they described the attenuating effect of inter-individual variation on the strength of associations with odds ratios, showing how even relatively minor within-person variability can reduce the strength of these associations [84]. Their work has recently been confirmed and updated by O’Brien and colleagues [85], and the Research Reactor Center at Missouri-Columbia University (USA) has been used by several other workers to examine nails for trace and essential elements. Most recently, Matthews et al. [83] analyzed samples from the same cohorts as Park et al. [41] to prospectively examine toenail trace elements and risk of skin cancer. They reported that incidence of both basal and squamous cell carcinoma was positively associated with ungual Hg, while Cr was associated with basal cell carcinoma incidence among women only.