Tracer Techniques
Mostrando 25-36 de 65 artigos, teses e dissertações.
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25. Multicompartmental Analysis of Calcium Kinetics in Normal Adult Males*
This report describes studies of calcium kinetics in ten normal young men. Serum, urinary, and fecal radioactivity was measured from 1 minute to 20 days after intravenous tracer 47Ca injection, and these results were analyzed jointly with data obtained from a simultaneous metabolic balance study, using digital computer techniques. Surface radioactivity measu
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26. Characterization of sodium transport in Acholeplasma laidlawii B cells and in lipid vesicles containing purified A. laidlawii (Na+-Mg2+)-ATPase by using nuclear magnetic resonance spectroscopy and 22Na tracer techniques.
The active transport of sodium ions in live Acholeplasma laidlawii B cells and in lipid vesicles containing the (Na+-Mg2+)-ATPase from the plasma membrane of this microorganism was studied by 23Na nuclear magnetic resonance spectroscopic and 22Na tracer techniques, respectively. In live A. laidlawii B cells, the transport of sodium was an active process in w
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27. Production rates and metabolic clearance rates of human follicle—stimulating hormone in premenopausal and postmenopausal women
The production rates (PR) and the metabolic clearance rates (MCR) of human follicle—stimulating hormone (HFSH) were determined in six pre- and five postmenopausal women. Human FSH (PER-780) labeled with 131I to specific activities of 50-150 μc/μg was used as a tracer. Both double antibody and trichloroacetic acid (TCA) precipitation techniques were used
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28. Assessment of left ventricular performance and myocardial viability using quantitative radioisotope techniques.
The diagnostic value of a combined radionuclide technique was compared with conventional angiocardiographic techniques in 60 patients with coronary artery disease. Quantitative 201Tl myocardial imaging combined with radionuclide angiocardiography using 99mTc-HSA provided a safe and accurate method for the assessment of left ventricular performance. The defec
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29. Direct Measurement of Osteolysis in Man
Precise, direct measurement of bone calcium release (vo-) has been accomplished using a continuous tracer administration (CTA) technique. Dietary calcium (96.97% 40Ca) is replaced by 40Ca (99.991% 40Ca) and blood levels of the naturally occuring isotope 48Ca are monitored by neutron activation analysis as a function of time. 48Ca abundance falls as this isot
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30. Rapid transcapillary exchange and unidirectional neuronal uptake of noradrenaline in the perfused rabbit heart.
Capillary permeability and cellular uptake of noradrenaline by the isolated artificially perfused rabbit heart was measured using rapid (less than 30 s) single-circulation tracer-dilution techniques. In a single coronary circulation capillary extractions of L-[14C]noradrenaline and D-[3H]mannitol (extracellular reference) relative to an intravascular marker,
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31. Gas Chromatography-Mass Spectrometry of N- Heptafluorobutyryl Isobutyl Esters of Amino Acids in the Analysis of the Kinetics of [15N]H4+ Assimilation in Lemna minor L
Rapid, sensitive, and selective methods for the determination of the 15N abundance of amino acids in isotopic tracer experiments with plant tissues are described and discussed. Methodology has been directly tested in an analysis of the kinetics of [15N]H4+ assimilation in Lemna minor L. The techniques utilize gas chromatography-mass spectrometry selected ion
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32. Detection of immunoglobulins G and M to rubella virus by time-resolved immunofluorometry.
We describe new methods for the detection of immunoglobulin G (IgG) and IgM rubella-specific antibodies in serum. The IgG assay was based on a solid-phase rubella antigen immobilization approach, and the IgM assay was based on the IgM capture assay principle. Both assays used biotinylated antibodies (anti-human IgG and antirubella monoclonal antibody, respec
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33. 15N NMR studies of nitrogen metabolism in intact mycelia of Neurospora crassa.
Suspensions of intact mycelia of Neurospora crassa grown in medium containing 15NH4Cl have been found to give well-resolved 15N nuclear magnetic resonance spectra for metabolites that play crucial roles in intermediary nitrogen metabolism. These include the amide nitrogen of glutamine, the alpha-amino nitrogens of glutamate and other amino acids, the guanidi
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34. Tracking neuronal fiber pathways in the living human brain
Functional imaging with positron emission tomography and functional MRI has revolutionized studies of the human brain. Understanding the organization of brain systems, especially those used for cognition, remains limited, however, because no methods currently exist for noninvasive tracking of neuronal connections between functional regions [Crick, F. & Jones
The National Academy of Sciences.
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35. Effect of Sulfhydryl Reagents on the Biophysical Properties of the Plasmalemma of Chara corallina1
The administration of the sulfhydryl reagent N-ethyl-maleimide (NEM) to internodal cells of Chara corallina caused alterations in the biophysical properties of the plasmalemma, as measured with electrophysiological and radioactive tracer techniques. The membrane potential depolarized to, or near, the calculated Nernst potential for potassium (EK) after 30 se
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36. Small circular DNA of Drosophila melanogaster: chromosomal homology and kinetic complexity.
Nucleic acid reassociation techniques were used to determine the kinetic complexity of small circular DNA in cultured cells of Drosophila melanogaster. Two kinetic components are present. One of these constitutes 82% of the mass of the circular DNA and has a complexity of 1.8 x 10(4) nucleotide pairs; the other constitutes 18% of the mass and the a significa