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Query: KEGG:D02259 (NaI)
 1,823 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cerebral blood flow (CBF) was determined in the rat under 70% nitrous oxide anesthesia and pentobarbital anesthesia. The application of the Fick principle technique of Kety et al. was modified utilizing 133Xe infused intravenously steadily for 30 seconds, at which time the animal was decapitated and the head frozen in liquid nitrogen. A prior femoral artery to femoral vein shunt was led through a polyethylene catheter of 0.13 ml volume. This catheter passed as a coil in a NaI crystal well-counter with the arterial 133Xe concentration curve recorded by a ratemeter-recorder system. The results of the hemispheric blood flow (HBF) were: under 70% nitrous oxide anesthesia in normocapnia (Paco2 38 mm Hg), 86 +/- 15 ml/100 gm per minute; with hypocapnia (Paco2 20 mm Hg), 40 +/- 5 ml/100 gm per minute; with hypercapnia (Paco2 63 mm Hg), 187 +/- 10 ml/100 gm per minute; and with pentobarbital anesthesia (Paco2 38 mm Hg), 41 +/- 8 ml/100 gm per minute.
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PMID:The measurement of cerebral blood flow in the rat. 12 60

The feasibility of using the information contained in the radiative capture gamma ray spectrum of the neutron-irradiated human body to measure quantitatively total body elemental composition in vivo has been investigated. Results of time dependent Monte Carlo simulations have shown that spectral interference of nonradiative capture origin can be completely eliminated by pulsing the detector/spectrometer system in anticoincidence with the neutron source. Calculations based on the results of the Monte Carlo simulation and on an experimental measurement of the efficiency versus energy characteristics of a Ge(Li) detector suggest that the primary limitation of the proposed technique would be inter-element spectral interference rather than inadequate detector sensitivity. Experimental measurements using a pulsed 14-MeV neutron generator and Ge(Li) gamma-ray spectrometer have produced results that are consistent with the predictions of the theoretical model. A radiative capture gamma-ray spectrum of a tissue-equivalent phantom was measured in pulsed mode and analyzed offline using a computerized spectral analysis procedure. The results were scaled to a proposed facility consisting of a 2.5-MeV pulsed neutron source and a detection system comprising two 50-cm3 (Ge(Li) detectros past which the subject would be scanned. It has been shown that in principle the elements hydrogen, chlorine, calcium, and nitrogen [the latter using large NaI(T1) detectors] could be measured with such a facility at an average body dose level of 0.1 rad. At this dose level the coefficients of variation based on counting statistics alone would be +/- 2%, or better, for these four elements. With an improvement in the detector/spectrometer energy resolution, the elements sulfur and carbon might also be measurable. It is also shown that by modifying the pulsing sequence appropriately and using 14-MeV neutrons, total body oxygen could also be measured at the 0.1 rad dose level via its inelastic neutron scattering deexcitation gamma activity.
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PMID:A feasibility study of prompt capture gamma in vivo neutron activation analysis. 47 Aug 41

A mehtod of measuring body nitrogen by neutron capture gamma analysis is described. The neutron flux is provided by four collimated 5 Ci Pu-Be sources, placed to give a bilateral irradiation of the subject. The 10-83 MeV thermal neutron capture gamma rays from 14N are detected by two heavily shielded 5 in X 4 in NaI(Tl) detectors. Results indicate a reproducibility +/-3% (1 SD) for a 10 min irradiation of the chest area, while giving a radiation dose equivalent of 50 mREM.
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PMID:In vivo determination of nitrogen using Pu-Be sources. 90 19

When preparing 99Tcm-exametazime, it is important to use sodium 99Tcm-pertechnetate that is less than 2 h old. The addition of sodium iodide (NaI) to 99Tcm-pertechnetate is known to extend this time to 6 h. This paper describes a technique for implementing this in routine practice. Sterile kits consisting of 440 micrograms NaI and 1.0 ml sodium chloride injection in a vial with a nitrogen atmosphere were prepared and stored at room temperature, 4 degrees C and -22 degrees C. Titrimetric analysis of iodide showed that under each storage condition, kits were stable for 8 weeks. To determine the effectiveness of the kits, the radiochemical purity (RCP) of 99Tcm-exametazime was measured by high-performance liquid chromatography (HPLC). The validity of this technique was determined by simultaneous analysis with the conventional thin-layer/paper chromatography (TLC/PC) technique on 24 occasions, over a range of RCP (94.5-54.6%). Radiochemical purities measured by HPLC and TLC/PC were 81.2 +/- 10.2 and 81.5 +/- 10.5%, respectively, and did not differ significantly (P greater than 0.30). The correlation between the techniques was high (r = 0.98). 99Tcm-exametazime was prepared using 1 h-old 99Tcm-pertechnetate, 6 h-old 99Tcm-pertechnetate and 6 h-old 99Tcm-pertechnetate dispensed in a NaI kit. At the recommended expiry time for this radiopharmaceutical, i.e. 30 min after preparation, RCPs were found to be 88.4 +/- 2.4, 80.9 +/- 2.0 and 89.3 +/- 3.0%, respectively (n = 5 for each technique).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A routine method for using sodium iodide to stabilize sodium pertechnetate [99Tcm] dispensed for the preparation of 99Tcm-exametazime. 131 30

Design studies relating to an in vivo prompt capture neutron activation analysis facility measuring total body nitrogen are presented. The basis of the design is a beryllium-graphite neutron collimator and reflector configuration for (alpha, n) type radionuclide neutron sources (238PuBe or 241AmBe), so as to reflect leaking, or out-scattered, neutrons towards the subject. This improves the ratio of thermal neutron flux to dose and the spatial distribution of thermal flux achieved with these sources, whilst retaining their advantage of long half-lives as compared to 252Cf based systems. The common problem of high count-rate at the detector, and therefore high nitrogen region of interest background due to pile-up, is decreased by using a set of smaller (5.1 cm diameter x 10.2 cm long) NaI(Tl) detectors instead of large ones. The facility described presents a relative error of nitrogen measurement of 3.6% and a nitrogen to background ratio of 2.3 for 0.45 mSv skin dose (assuming ten 5.1 cm x 10.2 cm NaI(Tl) detectors).
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PMID:Design studies related to an in vivo neutron activation analysis facility for measuring total body nitrogen. 151 6

An array of four large-volume coaxial germanium detectors was installed in a shielded room for the in vivo measurement of gamma emitters in the body. All four detectors are in a single 50-L dewar of liquid nitrogen and are positioned underneath the supine subject with the axes of the detector elements parallel with the length of the body. This orientation gives approximately 15% more counting efficiency than having the axes of the detectors perpendicular to the body length. The detectors have resolutions that are less than 2 keV with an average of 1.86 keV for the 60Co 1.33-MeV gamma-ray peak. The efficiencies of the four detectors range from 59% to 77% of a 7.62- x 7.62-cm (3- x 3-in.) NaI (Tl) detector. The detectors are interfaced to a multichannel analyzer such that spectra from the detectors are stored both as a sum of all counts from the four detectors and as a spectrum from each detector. The sensitivity of the germanium array for measuring radioactivity in the body exceeds that of multiple large NaI (Tl) detectors for measuring single radionuclides in the body and is much superior for measuring internal depositions of radionuclide mixtures. Another major advantage of this system compared to NaI(Tl) systems is that the results can be calculated by computer analysis with minimal human interpretation. The sensitivity of the array configuration is described and applications of the array in other configurations, such as that used for measuring the very small quantities of 24Na induced in the body during air travel, are also discussed.
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PMID:Performance of an array of large-volume germanium detectors for whole-body counting. 166 Dec 76

Nuclear magnetic resonance spectra of cultures of Candida albicans incubated in the presence of 15N-labelled ammonium demonstrated that glutamine and glutamate were the only initial products of ammonium assimilation. The nature of the route of assimilation in the yeasts Candida albicans, Saccharomyces cerevisiae, and Candida tropicalis was further examined by the use of the short-lived isotope 13N. [13N]ammonium was generated in the reaction 16O(p,alpha)13N, induced by proton bombardment of water in tandem accelerator. High-pressure liquid chromatography was used to separate and identify the products of assimilation, and radioactivity was detected and corrected for decay, using a computer-linked NaI scintillation detector. In the three yeasts studied, the labelled ammonium was assimilated into the acid-extractable fraction of cell suspensions within 1 min, and over 75% was converted to glutamine and glutamate. Subsequent to exhaustion of the labelled ammonium, the stoichiometry of the distribution of radiolabel was consistent with a net transfer of radiolabel from glutamine to glutamate, confirming the operation of glutamate synthase (EC 1.4.1.14) in these yeasts. Initial assimilation of label was mostly into glutamine (at a maximal rate within 10 s in C. albicans), whereas accumulation in glutamate did not occur at maximal rate until more than 70% of the labelled ammonium had been assimilated (between 30 and 60 s in C. albicans). We conclude that the glutamine synthetase-glutamate synthase pathway is the major route of ammonium assimilation in C. albicans and also in nitrogen-starved cultures of S. cerevisiae and C. tropicalis.
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PMID:Ammonium assimilation by Candida albicans and other yeasts: a 13N isotope study. 167 31

The design, calibration and evaluation of a facility for in vivo prompt gamma neutron capture analysis of total body nitrogen in children is described. The patient is scanned in both supine and prone positions, across a vertically collimated beam from a 1 GBq 252Cf fission source. Two NaI(T1) detectors are placed on either side of the patient, perpendicular to both the neutron beam and the scanning direction. The effective dose equivalent delivered to a child during an 840 s scan is approximately 0.14 mSv (QF = 10). Correction factors for nitrogen background (width-dependent), hydrogen background (1-4% of hydrogen gamma ray peak) and the differential attenuation of nitrogen and hydrogen gamma rays (width-dependent) can be applied to the measured nitrogen-to-hydrogen gamma ray counts ratio. By using the mass of hydrogen (based on body mass and fat mass) as an internal standard, the nitrogen mass can then be determined. Measurements with a urea-containing box phantom show that the current precision (CV) of the net nitrogen counts and of the nitrogen-to-hydrogen counts ratio is +/- 2.0% and +/- 1.5%, respectively. Using small anthropomorphic and other phantoms, estimation of the mass of nitrogen has a precision of +/- 1.4 to 5.4% and an accuracy of 97.1 to 101.5%.
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PMID:A total body nitrogen facility for paediatric use. 174 63

In a group of moderately severe asthmatic subjects, regional deposition of 3.6-microns (aerodynamic diameter) monodispersed Teflon particles labeled with 111In was studied twice. The particles were inhaled with maximally deep inhalation at 0.5 l/s. Lung retention was measured at 0, 6, 24, and 48 h by use of a profile scanner equipped with two 13 x 5-cm NaI crystals. The retentions at 24 (Ret24) and 48 h were highly correlated (r = 0.96 with a slope of the regression line close to 1). There was a poor correlation between retention at 6 h and Ret24 (r = 0.54). The Ret24 values at the two exposures were well correlated (r = 0.86). There were significant correlations between airway resistance as well as single-breath nitrogen test phase III and Ret24 (r = 0.70 and 0.67, respectively). The correlation between single-breath nitrogen test phase III and Ret24 persisted also when only subjects within a narrow interval of airway resistance were included. The study indicates that regional deposition can be studied by measurements of Ret24 in subjects with moderately severe asthma and that it is dependent on changes in both large and small airways.
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PMID:Regional deposition of 3.6-micron particles and lung function in asthmatic subjects. 177 19

The feasibility of using the time correlated associated particle technique for in vivo 14-MeV neutron activation analysis has been investigated. Gamma rays following neutron inelastic scattering with nitrogen, carbon, and oxygen have been measured with a 12.5 x 10-cm NaI (T1) detector. The results have been scaled to a proposed facility comprising four such detectors past which the subject would be scanned. Based on counting statistics, the precision of estimation of these elements has been determined to be 2.1%, 1.0%, and 1.1%, respectively, for experimental measurements on a sample containing physiological concentrations of the major body elements. The average body dose level would be restricted to 0.3 mSv.
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PMID:A feasibility study of in vivo 14-MeV neutron activation analysis using the associated particle technique. 196 Nov 54


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