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J.d. Harrison - One of the best experts on this subject based on the ideXlab platform.
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The Gastrointestinal Absorption and Urinary Excretion of Plutonium in Male Volunteers
Radiation Protection Dosimetry, 2000Co-Authors: G.j. Ham, J.d. HarrisonAbstract:The Gastrointestinal Absorption and urinary excretion of 244 Pu have been measured in five healthy adult males in a two-stage study. Firstly, the volunteers ingested about 10 14 atoms of 244 Pu in citrate solution with a mid-day meal and urinary excretion was measured for the following 7-9 days. After a period of at least six months, the same volunteers were given an intravenous injection of 2 x 10 12 atoms of 244 Pu in citrate solution. Urinary excretion was then measured for the following 7-9 days and subsequently at intervals over periods up to 5-6 years. Fractional Absorption of Pu from the Gastrointestinal tract, calculated by comparing excretion for the two routes of administration, averaged 6 X 10 -4 , consistent with the ICRP value of 5 x 10 -4 . The results show a positive correlation between increasing age of the subjects, between 36 and 64 years of age, and increasing Absorption of ingested Pu from 10 -4 to 10 -3 . In general, results for urinary excretion after injection are consistent with predictions of the current ICRP model although daily excretion after 5-6 years (3 subjects) averaged 0.005% of the administered amount, about twice the predicted value.
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The Gastrointestinal Absorption of neptunium, plutonium and americium in a primate (C. jacchus)
The Science of the total environment, 1994Co-Authors: G.j. Ham, J.d. Harrison, D.s. Popplewella, I. Garrod, J. Wilson, A. D. DayanAbstract:Abstract Mixtures of Np, Pu and Am were administered to primates (C. jacchus) by gastric intubation to measure their fractional Gastrointestinal Absorption (f1values). The values obtained were about 2 × 10−3 and 1 × 10−3, respectively, for Np and Pu administered as the citrate, and 2 × 10−3 and 6 × 10−4, respectively, for Pu and Am in potato. The significance of these values in terms of Absorption in humans is discussed.
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Measurements of the Gastrointestinal Absorption and tissue distribution of plutonium, americium and polonium in experimental animals.
The Science of the total environment, 1993Co-Authors: G.p.l. Naylor, J.w. Haines, K. Whysall, H.e. Bonas, J.d. HarrisonAbstract:Abstract In order to set limits on environmental and occupational intakes of radionuclides, information is needed on their uptake and metabolism in man. Human data are very limited, particularly for long-lived alpha-emitting isotopes such as those of the actinides. Animal experiments are therefore an important source of data on the distribution of radionuclides in tissues, and the effects of factors such as subject age and the chemical form of elements on Gastrointestinal Absorption. The NRPB performs experimental programs using mainly rats and guinea pigs. In order to study the Gastrointestinal Absorption and tissue distribution of plutonium, americium and polonium, a variety of analytical techniques are employed. These include ion exchange and solvent extraction leading to alpha spectrometry and liquid scintillation counting. The investigation of low specific-activity environmental or industrial materials, and the very low bioavailability of elements such as the actinides, means that very low levels of activity have to be measured. Contamination at the dissection and tissue separation stage, as well as during the radiochemistry, has to be rigorously avoided. Where very detailed information is needed on the location of radionuclides within tissues, such as in the study of alpha-emitter distribution in the intestine, autoradiography is used. The application and relevance of different measurement techniques to animal studies will be discussed andexamples of the results presented.
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Gastrointestinal Absorption and retention of polonium in adult and newborn rats and guinea pigs.
International journal of radiation biology, 1993Co-Authors: J.w. Haines, G.p.l. Naylor, H.e. Pottinger, J.d. HarrisonAbstract:The Gastrointestinal Absorption of 210Po was determined by comparing tissue retention after oral and systemic administration. The results indicate an increase in Absorption in adult rats for 210Po administered in liver compared with 210Po nitrate with estimated Absorption of 5 and 13%, respectively. For 210Po citrate, values of about 7% were obtained in 1-day-old neonate and adult rats while Absorption in guinea pigs was estimated to be about 23% in 1-day-old neonates, 17% in 5-day-old neonates, and 9% in adults. Gut retention of ingested 210Po in neonates was high in rats but not guinea pigs. In adult animals, but not neonates, the liver accounted for a greater proportion of 210Po reaching the bloodstream after ingestion than after systemic injection. The significance of these results is discussed in relation to current assumptions made in the calculation of doses from 210Po.
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Gastrointestinal Absorption of neptunium and curium in humans.
Health physics, 1991Co-Authors: D.s. Popplewell, J.d. Harrison, G.j. HamAbstract:The Gastrointestinal Absorption of Np and Cm has been determined in five male adult volunteers. The Np and Cm, which were in citrate solution, were taken with food. An initial experiment with each individual determined the fraction of each element excreted in the urine following intravenous administration. Subsequently, the results for urinary excretion for the two routes of administration were used to calculate the fractional Absorption (f1) of ingested Np and Cm. The mean f1 values were: Np (2.0 +/- 0.2) X 10{sup {minus} 4}, range (1.2-2.9) X 10{sup {minus} 4}, and Cm (1.7 +/- 0.3) X 10{sup {minus} 4}, range (0.95-3.0) X 10{sup {minus} 4}, the quoted uncertainties being the standard error of the means. Currently, the International Commission on Radiological Protection recommends a value of 10{sup {minus} 3} for both elements. Cumulative urinary excretion over 1 wk after intravenous injection accounted for about 20%-40% of administered Np and 7%-10% of Cm. At the conclusion of the experiment, the total committed effective dose equivalent for each volunteer was calculated to be in the range 130-250 microSv, based on the individual f1 values, and, in some cases, a knowledge of the rate of clearance of {sup 239}Np through the gutmore » as measured by whole-body counting.« less
G.j. Ham - One of the best experts on this subject based on the ideXlab platform.
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The Gastrointestinal Absorption and Urinary Excretion of Plutonium in Male Volunteers
Radiation Protection Dosimetry, 2000Co-Authors: G.j. Ham, J.d. HarrisonAbstract:The Gastrointestinal Absorption and urinary excretion of 244 Pu have been measured in five healthy adult males in a two-stage study. Firstly, the volunteers ingested about 10 14 atoms of 244 Pu in citrate solution with a mid-day meal and urinary excretion was measured for the following 7-9 days. After a period of at least six months, the same volunteers were given an intravenous injection of 2 x 10 12 atoms of 244 Pu in citrate solution. Urinary excretion was then measured for the following 7-9 days and subsequently at intervals over periods up to 5-6 years. Fractional Absorption of Pu from the Gastrointestinal tract, calculated by comparing excretion for the two routes of administration, averaged 6 X 10 -4 , consistent with the ICRP value of 5 x 10 -4 . The results show a positive correlation between increasing age of the subjects, between 36 and 64 years of age, and increasing Absorption of ingested Pu from 10 -4 to 10 -3 . In general, results for urinary excretion after injection are consistent with predictions of the current ICRP model although daily excretion after 5-6 years (3 subjects) averaged 0.005% of the administered amount, about twice the predicted value.
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The Gastrointestinal Absorption of neptunium, plutonium and americium in a primate (C. jacchus)
The Science of the total environment, 1994Co-Authors: G.j. Ham, J.d. Harrison, D.s. Popplewella, I. Garrod, J. Wilson, A. D. DayanAbstract:Abstract Mixtures of Np, Pu and Am were administered to primates (C. jacchus) by gastric intubation to measure their fractional Gastrointestinal Absorption (f1values). The values obtained were about 2 × 10−3 and 1 × 10−3, respectively, for Np and Pu administered as the citrate, and 2 × 10−3 and 6 × 10−4, respectively, for Pu and Am in potato. The significance of these values in terms of Absorption in humans is discussed.
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Gastrointestinal Absorption of neptunium and curium in humans.
Health physics, 1991Co-Authors: D.s. Popplewell, J.d. Harrison, G.j. HamAbstract:The Gastrointestinal Absorption of Np and Cm has been determined in five male adult volunteers. The Np and Cm, which were in citrate solution, were taken with food. An initial experiment with each individual determined the fraction of each element excreted in the urine following intravenous administration. Subsequently, the results for urinary excretion for the two routes of administration were used to calculate the fractional Absorption (f1) of ingested Np and Cm. The mean f1 values were: Np (2.0 +/- 0.2) X 10{sup {minus} 4}, range (1.2-2.9) X 10{sup {minus} 4}, and Cm (1.7 +/- 0.3) X 10{sup {minus} 4}, range (0.95-3.0) X 10{sup {minus} 4}, the quoted uncertainties being the standard error of the means. Currently, the International Commission on Radiological Protection recommends a value of 10{sup {minus} 3} for both elements. Cumulative urinary excretion over 1 wk after intravenous injection accounted for about 20%-40% of administered Np and 7%-10% of Cm. At the conclusion of the experiment, the total committed effective dose equivalent for each volunteer was calculated to be in the range 130-250 microSv, based on the individual f1 values, and, in some cases, a knowledge of the rate of clearance of {sup 239}Np through the gutmore » as measured by whole-body counting.« less
Kishor M. Wasan - One of the best experts on this subject based on the ideXlab platform.
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Does P-Glycoprotein Play a Role in Gastrointestinal Absorption and Cellular Transport of Dietary Cholesterol?
Drug development and industrial pharmacy, 2006Co-Authors: Carlos G. Leon, Kristina Sachs-barrable, Kishor M. WasanAbstract:This commentary discusses the potential role of p-glycoprotein (Pgp) on the Gastrointestinal Absorption and cellular transport of dietary cholesterol. This is currently a controversial issue due to the conflicting evidence about the role of this ABC transporter in cholesterol transport. During the preparation of this commentary, several key publications on this topic arguing for and against this mechanism have been published. If true, this mechanism of Pgp could represent a novel role for Pgp and provide a potentially new molecular target for drug design and development.
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potential mechanisms by which peceol increases the Gastrointestinal Absorption of amphotericin b
Drug Development and Industrial Pharmacy, 2004Co-Authors: Verica Risovic, Kristina Sachsbarrable, Michael Boyd, Kishor M. WasanAbstract:Purpose, The purpose of this study was to ascertain how the incorporation of AmpB into a glyceride‐rich excipient Peceol® significantly increased Amphotericin B's (AmpB) Gastrointestinal Absorption in white male Sprague‐Dawley rats. Based on preliminary studies, our working hypothesis was that incorporation of AmpB into mixed micelles composed of Peceol® would significantly enhance gastro‐intestinal (GI) tract Absorption by increasing lymphatic drug transport and decreasing P‐glycoprotein (PGP) mediated drug efflux. Methods. I. Lymphatic Transport Studies: Following an overnight fast (12–16 hr) and 48 hr postsurgery, rats were divided into two treatment groups and received a single‐dose oral gavage (1 mL total volume) at 0700 h of either desoxycholates (DOC)–AmpB (5 mg AmpB/kg; n = 6 at each time point) or AmpB incorporated into 100% Peceol (Peceol®–AmpB; 5 mg AmpB/kg; n = 6 at each time point). Mesenteric lymph samples were obtained prior to and at 0–4‐hr, 4–6‐hr, and 6–8‐hr intervals post oral gavage. A...
J.w. Haines - One of the best experts on this subject based on the ideXlab platform.
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Measurements of the Gastrointestinal Absorption and tissue distribution of plutonium, americium and polonium in experimental animals.
The Science of the total environment, 1993Co-Authors: G.p.l. Naylor, J.w. Haines, K. Whysall, H.e. Bonas, J.d. HarrisonAbstract:Abstract In order to set limits on environmental and occupational intakes of radionuclides, information is needed on their uptake and metabolism in man. Human data are very limited, particularly for long-lived alpha-emitting isotopes such as those of the actinides. Animal experiments are therefore an important source of data on the distribution of radionuclides in tissues, and the effects of factors such as subject age and the chemical form of elements on Gastrointestinal Absorption. The NRPB performs experimental programs using mainly rats and guinea pigs. In order to study the Gastrointestinal Absorption and tissue distribution of plutonium, americium and polonium, a variety of analytical techniques are employed. These include ion exchange and solvent extraction leading to alpha spectrometry and liquid scintillation counting. The investigation of low specific-activity environmental or industrial materials, and the very low bioavailability of elements such as the actinides, means that very low levels of activity have to be measured. Contamination at the dissection and tissue separation stage, as well as during the radiochemistry, has to be rigorously avoided. Where very detailed information is needed on the location of radionuclides within tissues, such as in the study of alpha-emitter distribution in the intestine, autoradiography is used. The application and relevance of different measurement techniques to animal studies will be discussed andexamples of the results presented.
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Gastrointestinal Absorption and retention of polonium in adult and newborn rats and guinea pigs.
International journal of radiation biology, 1993Co-Authors: J.w. Haines, G.p.l. Naylor, H.e. Pottinger, J.d. HarrisonAbstract:The Gastrointestinal Absorption of 210Po was determined by comparing tissue retention after oral and systemic administration. The results indicate an increase in Absorption in adult rats for 210Po administered in liver compared with 210Po nitrate with estimated Absorption of 5 and 13%, respectively. For 210Po citrate, values of about 7% were obtained in 1-day-old neonate and adult rats while Absorption in guinea pigs was estimated to be about 23% in 1-day-old neonates, 17% in 5-day-old neonates, and 9% in adults. Gut retention of ingested 210Po in neonates was high in rats but not guinea pigs. In adult animals, but not neonates, the liver accounted for a greater proportion of 210Po reaching the bloodstream after ingestion than after systemic injection. The significance of these results is discussed in relation to current assumptions made in the calculation of doses from 210Po.
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The Gastrointestinal Absorption and retention of niobium in adult and newborn guinea pigs.
International journal of radiation biology, 1990Co-Authors: J.d. Harrison, J.w. Haines, D.s. PopplewellAbstract:SummaryThe Gastrointestinal Absorption of 95Nb ingested in milk by adult guinea pigs on a milk-supplemented diet was estimated as 0·8 ± 0·2% (SEM; n = 4) and a value of 1·4 ± 0·2% was obtained for guinea pigs fasted for 24 h before and 2 h after the oral administration of 95Nb in a citrate solution. The Absorption in 2-day-old animals given the 95Nb–citrate solution was estimated as 1·5 ± 0·2% (SEM; n = 3). These results support the values currently used for radiological protection purposes to calculate doses from the ingestion of niobium isotopes; these are 1% for adults and 2% for infants in the first year of life. Intestinal retention of niobium in newborn guinea pigs was low, unlike retention in other species, but consistent with observations of the retention of other elements in guinea pigs. It is considered that retention in human neonates is likely to be most similar to that in guinea pigs. Whole-body retention of 95Nb after systemic administration in citrate solution was slightly lower in 2-day-ol...
G.p.l. Naylor - One of the best experts on this subject based on the ideXlab platform.
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Measurements of the Gastrointestinal Absorption and tissue distribution of plutonium, americium and polonium in experimental animals.
The Science of the total environment, 1993Co-Authors: G.p.l. Naylor, J.w. Haines, K. Whysall, H.e. Bonas, J.d. HarrisonAbstract:Abstract In order to set limits on environmental and occupational intakes of radionuclides, information is needed on their uptake and metabolism in man. Human data are very limited, particularly for long-lived alpha-emitting isotopes such as those of the actinides. Animal experiments are therefore an important source of data on the distribution of radionuclides in tissues, and the effects of factors such as subject age and the chemical form of elements on Gastrointestinal Absorption. The NRPB performs experimental programs using mainly rats and guinea pigs. In order to study the Gastrointestinal Absorption and tissue distribution of plutonium, americium and polonium, a variety of analytical techniques are employed. These include ion exchange and solvent extraction leading to alpha spectrometry and liquid scintillation counting. The investigation of low specific-activity environmental or industrial materials, and the very low bioavailability of elements such as the actinides, means that very low levels of activity have to be measured. Contamination at the dissection and tissue separation stage, as well as during the radiochemistry, has to be rigorously avoided. Where very detailed information is needed on the location of radionuclides within tissues, such as in the study of alpha-emitter distribution in the intestine, autoradiography is used. The application and relevance of different measurement techniques to animal studies will be discussed andexamples of the results presented.
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Gastrointestinal Absorption and retention of polonium in adult and newborn rats and guinea pigs.
International journal of radiation biology, 1993Co-Authors: J.w. Haines, G.p.l. Naylor, H.e. Pottinger, J.d. HarrisonAbstract:The Gastrointestinal Absorption of 210Po was determined by comparing tissue retention after oral and systemic administration. The results indicate an increase in Absorption in adult rats for 210Po administered in liver compared with 210Po nitrate with estimated Absorption of 5 and 13%, respectively. For 210Po citrate, values of about 7% were obtained in 1-day-old neonate and adult rats while Absorption in guinea pigs was estimated to be about 23% in 1-day-old neonates, 17% in 5-day-old neonates, and 9% in adults. Gut retention of ingested 210Po in neonates was high in rats but not guinea pigs. In adult animals, but not neonates, the liver accounted for a greater proportion of 210Po reaching the bloodstream after ingestion than after systemic injection. The significance of these results is discussed in relation to current assumptions made in the calculation of doses from 210Po.
