A suggested revision to the specific activity limit for tritiated water transported as LSA-II

2003 ◽  
Vol 14 (3-4) ◽  
pp. 193-197
Author(s):  
A. N. Nandakumar
Keyword(s):  
Specific Activity ◽  
Tritiated Water

Estimation of water content by tritium dilution of animals subjected to rapid live-weight changes

1969 ◽  
Vol 72 (1) ◽  
pp. 31-40 ◽  
Author(s):  
W. R. McManus ◽  
R. K. Prichard ◽  
Carolyn Baker ◽  
M. V. Petruchenia
Keyword(s):  
Body Weight ◽  
Water Content ◽  
Total Body Water ◽  
Compensatory Growth ◽  
Specific Activity ◽  
Tritiated Water ◽  
Body Water ◽  
Under Nutrition ◽  
The Mean ◽  
Total Body

SUMMARYThe use of tritiated water to estimate total body-water content of animals experiencing recovery from under-nutrition was studied.The time for equilibration of tritiated water (TOH), given intraperitoneally, with total body water (TBW) was determined in rabbits and in rats. As judged by the specific activity of blood water, equilibration had occurred by 76–125 min in the rabbit and did not appear to be affected by the plane of nutrition. However, between slaughter groups the specific activity of water obtained from the liver 180 min after injection of TOH was significantly different from the specific activity of water simultaneously obtained from the blood plasma. It is concluded that the liver is not a suitable tissue to use for testing achievement of equilibration.As judged by the specific activity of blood water compared to that of water from the whole body macerate, equilibration in mature rats either in stable body condition or undergoing rapid compensatory growth occurred in less than 60 min.A trial comparing TOH-space (corrected by 3% body weight) and actual TBW (by desiccation) was conducted on thirty rabbits which experienced under-nutrition followed by compensatory growth.Prior to under-nutrition the agreement between actual and estimated TBW was satisfactory and within 2·3%. During compensatory growth the agreement was poor— the TOH values over-estimating actual TBW by about 12%.A trial with mature rats confirmed the findings with rabbits. For rats in stable body weight the mean estimated TOH-space for fourteen animals was within 1·2% of the actual TBW. For fourteen rats undergoing compensatory growth the mean estimated TOH-space (corrected by 3% body weight) overestimated actual TBW by 6·2%.

Self-radiation induced exchange between tritiated water and organic compounds. The labelling of L-chiro-inositol, myo-inositol and Hexa-O-methyl-L-chiro-inositol

1975 ◽  
Vol 28 (9) ◽  
pp. 1981 ◽  
Author(s):  
DHT Fong ◽  
CL Bodkin ◽  
MA Long ◽  
JL Garnett
Keyword(s):  
Organic Compounds ◽  
Radiochemical Purity ◽  
Specific Activity ◽  
Tritiated Water ◽  
High Specific Activity ◽  
Methyl Derivative ◽  
Radiation Induced ◽  
By Products ◽  
Gas Exposure

The stereochemistry of the tritiation of L-chiro-inositol, myo-inositol and hexa-O-methyl-L-chiro-inositol by self-radiation induced exchange with tritiated water of high specific activity has been investigated. Predominance of configurational retention was found to accompany tritium labelling in the two inositols, while substantial configurational inversion occurred in the hexa-O-methyl derivative. Tritiation occurred predominantly at C 1 in L-chiro-inositol, with slight inversion at this position alone accompanying the labelling. Comparison with Wilzbach T2 gas exposure results indicates the HTO method yields less by-products, myo-inositol having a radiochemical purity of 97%.

Preparation of 14C- and 3H-Labeled Aflatoxins

1971 ◽  
Vol 54 (5) ◽  
pp. 1027-1031
Author(s):  
J L Ayres ◽  
D J Lee ◽  
R O Sinnhuber
Keyword(s):  
Thin Layer ◽  
Aspergillus Flavus ◽  
Column Chromatography ◽  
Aflatoxin B1 ◽  
Sodium Acetate ◽  
Specific Activity ◽  
Tritiated Water ◽  
New Method ◽  
Extraction And Purification ◽  
Constant Specific Activity

Abstract A new method for the preparation of 14C- and 3H-labeled aflatoxins was devised, using rice as a supporting mold media. Labeled precursors were added to sterile rice and the mixture was inoculated with Aspergillus flavus spores. After a 7 day incubation at 25°C, the toxins were extracted with chloroform and purified by column chromatography and subsequent recrystallization. Aflatoxins B1 and G1 were recovered with 70% efficiency from the culture. Incorporation of radioactivity was examined with glucose-U-14C, sodium acetate-1-14C, and sodium acetate-2-14C. The latter gave the most efficient incorporation of 14C at 0.1% for aflatoxin B1 and 0.05% for aflatoxin G1. Conversion of 3H from tritiated water was 0.006% for aflatoxin B1 and 0.003% for aflatoxin G1. Extensive tests of radiopurity were performed on the labeled toxin which included: recrystallization to constant specific activity, thin layer and column chromatography, and hydrogenation of aflatoxin B1 to tetrahydrodeoxoaflatoxin B1. The rice-culturing technique gave good toxin yields of 1 mg aflatoxin B1/g rice. The purification was simplified by the absence of highly radioactive impurities and no appreciable degradation of labeled toxins was noted throughout extraction and purification.

Gypsum labelled with tritiated water as a marker for estimating supplement intake by individual sheep fed in groups

1984 ◽  
Vol 24 (127) ◽  
pp. 484 ◽  
Author(s):  
H Dove
Keyword(s):  
Specific Activity ◽  
Tritiated Water ◽  
Rapeseed Meal ◽  
Mean Difference ◽  
Sunflower Meal ◽  
Measurement Variability ◽  
Plaster Of Paris ◽  
The Mean ◽  
Stocking Rates ◽  
Supplement Intake

Three experiments were conducted to evaluate gypsum, labelled in its water of crystallization with tritiated water (TOH), as a marker substance for estimating the intake of solid supplements by grazing ruminants. The TOH-gypsum was prepared by mixing plaster of Paris with TOH and was then incorporated into pelleted supplements of sunflower meal (SFM) or rapeseed meal (RSM). All gypsum specific activity could be recovered by 48 h extraction with 0.02 M NaEDTA, but not 48 h extraction with water. When known levels of labelled SFM were fed to housed lambs, the mean difference between known and estimated intake was 4% or 28 g/d. The slope of the regression relating these intakes was not significantly different from 1 0. In the second experiment, the same lambs were offered labelled SFM outdoors, from communal troughs, at daily rates of 400 or 1000 g/head. In the first group, mean intake estimated from the marker was 2% or 8 g/d different from that estimated from trough measurements. In the second group, spillage and trampling of supplements was observed, and intake estimated using the marker was only 88% of that estimated from trough measurement. Variability between animals in intake was high and ranged from 336 to 1302 g/d over the two feeding levels. Accuracy of the marker method was confirmed in a third study with Merinos grazing wheat stubbles at two stocking rates, supplemented with 325 g/d of SFM or RSM. Those offered RSM ate very little, but intake was accurately detected down to levels of less than 30 g/d. The results are discussed in relation to possible sources of error, particularly day-to-day variations in individual intake.

Synthesis of physiologically active tritiated compounds using high specific activity tritiated water

1999 ◽  
Vol 42 (9) ◽  
pp. 859-866 ◽  
Author(s):  
Nikolai F. Myasoedov ◽  
Georgy V. Sidorov ◽  
Vladimir N. Kramerov ◽  
Vyacheslav I. Mishin
Keyword(s):  
Specific Activity ◽  
Tritiated Water ◽  
High Specific Activity

The effect of route of dosing and method of estimation of tritiated water space on the determination of total body water and the prediction of body fat in sheep

1974 ◽  
Vol 82 (1) ◽  
pp. 105-112 ◽  
Author(s):  
B. S. W. Smith ◽  
A. R. Sykes
Keyword(s):  
Body Weight ◽  
Body Fat ◽  
Total Body Water ◽  
Specific Activity ◽  
Tritiated Water ◽  
Multiple Correlation Coefficient ◽  
Body Water ◽  
Total Body ◽  
Water Space

SUMMARYEight mature female sheep were offered a ration which maintained body weight constant during a 20-week period. During the final 10 weeks a comparison was made in each animal of the pattern of equilibration and urinary losses of tritiated water during 8 h after dosing by four different routes. These were intravenous, intraperitoneal, intraruminal and a combination of the intraperitoneal and intraruminal routes. Tritiated water spaces were calculated from (a) the 8-h plasma specific activity and (b) by extrapolation to zero time of the plasma specific activities during the 7 days after injection. At the end of the experiment the fat and water contents of the bodies of the sheep were determined directly.Complete equilibration of tritiated water between plasma and rumen water was not achieved in all animals 8 h after intravenous or intraperitoneal injection but was when the rumen was primed by the combination of intraperitoneal and intraruminal dosing. After intraruminal dosing equilibration was not achieved in any animal within 8 h of dosing.Urinary losses of marker were lower after intraruminal dosing but otherwise averaged 4–5 % of the dose/1 urine. This was equivalent to 0·3–6·7% of the dose for individual sheep.Errors resulting from incomplete equilibration and urinary loss of marker did not influence the efficiency of prediction of total body water from tritiated water space. The multiple correlation coefficient relating body fat with empty body weight and its water content was very high (r = 0·99). Errors introduced into this relationship by the inclusion of gut water in the prediction equations were apparently of a similar magnitude to those resulting from the errors in the estimation of tritiated water space.The extrapolation method for the determination of tritiated water space was shown to have the same accuracy as equilibration techniques under these controlled dietary conditions.

Radioassay of Low Specific Activity Tritiated Water by Improved Liquid Scintillation Techniques

1957 ◽  
Vol 29 (12) ◽  
pp. 1774-1776 ◽  
Author(s):  
C. A. Ziegler ◽  
D. J. Chleck ◽  
J. Brinkerhoff
Keyword(s):  
Liquid Scintillation ◽  
Specific Activity ◽  
Tritiated Water

Water flux across the rat jejunum and ileum

1970 ◽  
Vol 29 (1) ◽  
pp. 130-132 ◽  
Author(s):  
Eugene Y. Berger ◽  
Rene Pecikyan ◽  
Grace Kanzaki
Keyword(s):  
Specific Activity ◽  
Tritiated Water ◽  
Water Flux ◽  
Rat Jejunum ◽  
Perfusion System ◽  
In Vitro Perfusion ◽  
Experimental Conditions ◽  
Single Determination ◽  
Observation Period

The flux of tritiated water from mucosa to serosa and from serosa to mucosa was measured across the rat ileum and rat jejunum in an in vitro perfusion system. The rate at which the specific activity of tritiated water decreased with time was an almost linear logarithmic function in the ileal serosal bath, whereas under identical conditions the rate of decrease was plainly curvilinear in the jejunal serosal bath. In comparing the first 40 min to the subsequent 60–100 min, the flux from mucosa to serosa across the ileum increased by 6.7 ± 5.6% in 12 comparisons, while the flux across the jejunum decreased by 21.O ± 9.9% in 7 comparisons. These observations illustrate the pitfall in determining flux rates based on a single determination at the beginning and end of an observation period. They illustrate the necessity of setting experimental conditions to be able to obtain intervening determinations to have some assurance that flux has not changed during the period of measurement. tritiated water flux

Cerebral metabolism of doubly labeled glucose in humans in vivo

1965 ◽  
Vol 20 (1) ◽  
pp. 117-130 ◽  
Author(s):  
William Sacks
Keyword(s):  
Specific Activity ◽  
Cerebral Metabolism ◽  
Venous Blood ◽  
Tritiated Water ◽  
Krebs Cycle ◽  
Succinic Semialdehyde ◽  
Active Pool ◽  
Specific Activities ◽  
Experimental Values

With glucose-3-C14 as injected substrate, the production of C14O2 almost kept pace with the net uptake of C14 by brain. Brain C14O2 specific activities practically coincided with venous blood glucose specific activities. This rapid production of C14O2 with little or no dilution of C14 led to the derivation of theoretical curves for glucose-2-, glucose-1-, or glucose-6-C14 experiments. The dissimilarity between theoretical and experimental values suggested that there is a significant dilution of C14 in traversing the Krebs cycle. Equations derived from hypothetical metabolic pathways which included a pool of substrate, x, were employed to match theoretical with average experimental values. In experiments with doubly labeled glucose-C14-T, brain TOH (tritiated water) specific activities were used to derive brain C14O2 specific activity values which closely approximated actual results. A scheme for human cerebral metabolism of glucose in vivo, which includes a small, metabolically active pool of glutamate, ggr-aminobutyrate, and succinic semialdehyde, is proposed. brain glucose oxidation; in vivo brain metabolism; isotopic glucose metabolism; glucose-C14-T cerebral metabolism Submitted on February 3, 1964

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