ISO standars on test methods for water radioactivity monitoring

Water is vital to humans and each of us needs at least 1.5 L of safe water a day to drink. Beginning as long ago as 1958 the World Health Organization (WHO) has published guidelines to help ensure water is safe to drink. Focused from the start on monitoring radionuclides in water, and continually cooperating with WHO, the International Standardization Organization (ISO) has been publishing standards on radioactivity test methods since 1978. As reliable, comparable and"fit for purpose" results are an essential requirement for any public health decision based on radioactivity measurements, international standards of tested and validated radionuclide test methods are an important tool for production of such measurements. This paper presents the ISO standards already published that could be used as normative references by testing laboratories in charge of radioactivity monitoring of drinking water as well as those currently under drafting and the prospect of standardized fast test methods in response to a nuclear accident.

Impaired uptake of glutathione by hepatic mitochondria from chronic ethanol-fed rats. Tracer kinetic studies in vitro and in vivo and susceptibility to oxidant stress.

Isolated hepatocytes incubated with [35S]-methionine were examined for the time-dependent accumulation of [35S]-glutathione (GSH) in cytosol and mitochondria, the latter confirmed by density gradient purification. In GSH-depleted and -repleted hepatocytes, the increase of specific activity of mitochondrial GSH lagged behind cytosol, reaching nearly the same specific activity by 1-2 h. However, in hepatocytes from ethanol-fed rats, the rate of increase of total GSH specific radioactivity in mitochondria was markedly suppressed. In in vivo steady-state experiments, the mass transport of GSH from cytosol to mitochondria and vice versa was 18 nmol/min per g liver, indicating that the half-life of mitochondrial GSH was approximately 18 min in controls. The fractional transport rate of GSH from cytosol to mitochondria, but not mitochondria to cytosol, was significantly reduced in the livers of ethanol-fed rats. Thus, ethanol-fed rats exhibit a decreased mitochondrial GSH pool size due to an impaired entry of cytosol GSH into mitochondria. Hepatocytes from ethanol-fed rats exhibited a greater susceptibility to the oxidant stress-induced cell death from tert-butylhydroperoxide. Incubation with glutathione monoethyl ester normalized the mitochondrial GSH and protected against the increased susceptibility to t-butylhydroperoxide, which was directly related to the lowered mitochondrial GSH pool size in ethanol-fed cells.

Rat insulin turnover in vivo

Zucker lean and obese rats were injected under pentobarbital anesthesia with 125I-labeled insulin; at timed intervals from 30 to 120 sec, blood samples were extracted and used for the estimation of insulin levels by RIA. A group of rats from each series was maintained under a constant infusion of noradrenaline. For each insulin determination, a duplicate blood sample containing the same amount of insulin as that used in the RIA, but without the radioactive label, was used as a blank for insulin measurement. The radioactivity in these tubes was then used for the measurement of insulin label per ml blood. From plasma label decay curves and insulin concentrations, the insulin pool size, half-life, and rate of degradation were calculated. Obese rats had higher insulin levels (2.43 nM) and showed less effect of noradrenaline than their lean counterparts, in which insulin distribution volume shrank with noradrenaline treatment. The half-life of plasma insulin was similar in all groups (range, 226-314 sec). Pool size and overall degradation rates were higher in obese (198 femtokatals) than in lean rats (28 femtokatals). It is postulated that obese rats synthesize and cleave much more insulin than lean controls despite their higher circulating levels of insulin.

Plasma leptin turnover rates in lean and obese Zucker rats

Conscious female adult lean and obese Zucker rats were injected through the jugular vein with radioactive iodine-labeled murine leptin; in the ensuing 8 min, four blood samples were sequentially extracted from the carotid artery. The samples were used in a modified RIA for leptin, in which paired tubes received the same amount of either labeled or unlabeled leptin, thus allowing us to estimate both leptin levels and specific radioactivity. The data were used to determine the decay curve parameters from which the half-life of leptin (5.46 ± 0.23 min for lean rats and 6.99 ± 0.75 min for obese rats) as well as the size of its circulating pool (32 pmol/kg for lean rats and 267 pmol/kg for obese rats) and the overall degradation rate (96 fkat/kg for lean rats and 645 fkat/kg for obese rats) were estimated. These values are consistent with the hormonal role of leptin and the need for speedy changes in its levels in response to metabolic challenge.

Liquid and solid scintillation: principles and applications

Scintillation counting is one of the most important developments in the application of radioisotopes to procedures needed by scientists, physicians, engineers, and technicians from many diverse discipline for the detection and quantitative measurement of radioactivity. In fact, Scintillation is the most sensitive and versatile technique for the detection and quantification ofradioactivity. Particularly, Solid and Liquid scintillation measurement are,nowadays, standard laboratory methods in the life-sciences for measuringradiation from gamma- and beta-emitting nuclides, respectively. Thismethodology is used routinely in the vast majority of diagnostic and/or researchlaboratories from those of biochemistry and biology to clinical departments.

Simultaneous determination of gross alpha, gross beta and Ra-226 in natural water by liquid scintillation counting.

The determination of gross alpha, gross beta and 226Ra activity in natural waters is useful in a wide range of environmental studies. Furthermore, gross alpha and gross beta parameters are included in international legislation on the quality of drinking water [Council Directive 98/83/EC].1 In this work, a low-background liquid scintillation counter (Wallac, Quantulus 1220) was used to simultaneously determine gross alpha, gross beta and 226Ra activity in natural water samples. Sample preparation involved evaporation to remove 222Rn and its short-lived decay daughters. The evaporation process concentrated the sample ten-fold. Afterwards, a sample aliquot of 8 mL was mixed with 12 mL of Ultima Gold AB scintillation cocktail in low-diffusion vials. In this study, a theoretical mathematical model based on secular equilibrium conditions between 226Ra and its short-lived decay daughters is presented. The proposed model makes it possible to determine 226Ra activity from two measurements. These measurements also allow determining gross alpha and gross beta simultaneously. To validate the proposed model, spiked samples with different activity levels for each parameter were analysed. Additionally, to evaluate the model's applicability in natural water, eight natural water samples from different parts of Spain were analysed. The eight natural water samples were also characterised by alpha spectrometry for the naturally occurring isotopes of uranium (234U, 235U and 238U), radium (224Ra and 226Ra), 210Po and 232Th. The results for gross alpha and 226Ra activity were compared with alpha spectrometry characterization, and an acceptable concordance was obtained.

Simultaneous determination of gross alpha, gross beta and Ra-226 in natural water by liquid scintillation counting.

The determination of gross alpha, gross beta and 226Ra activity in natural waters is useful in a wide range of environmental studies. Furthermore, gross alpha and gross beta parameters are included in international legislation on the quality of drinking water [Council Directive 98/83/EC].1 In this work, a low-background liquid scintillation counter (Wallac, Quantulus 1220) was used to simultaneously determine gross alpha, gross beta and 226Ra activity in natural water samples. Sample preparation involved evaporation to remove 222Rn and its short-lived decay daughters. The evaporation process concentrated the sample ten-fold. Afterwards, a sample aliquot of 8 mL was mixed with 12 mL of Ultima Gold AB scintillation cocktail in low-diffusion vials. In this study, a theoretical mathematical model based on secular equilibrium conditions between 226Ra and its short-lived decay daughters is presented. The proposed model makes it possible to determine 226Ra activity from two measurements. These measurements also allow determining gross alpha and gross beta simultaneously. To validate the proposed model, spiked samples with different activity levels for each parameter were analysed. Additionally, to evaluate the model's applicability in natural water, eight natural water samples from different parts of Spain were analysed. The eight natural water samples were also characterised by alpha spectrometry for the naturally occurring isotopes of uranium (234U, 235U and 238U), radium (224Ra and 226Ra), 210Po and 232Th. The results for gross alpha and 226Ra activity were compared with alpha spectrometry characterization, and an acceptable concordance was obtained.

Verifique sus conocimientos sobre radioprotección

La protección radiológica en radiodiagnóstico merece una atención específica que abordaremos en esta entrega que forma parte de una serie sobre pruebas complementarias que se inició en el Nursing2007 de abril. La utilización de técnicas basadas en el uso de radiación ionizante es muy habitual en nuestro entorno laboral. En estas técnicas intervienen cada vez más profesionales de enfermería, tanto desde un punto de vista de la realización, como de supervisión y de apoyo del médico en su realización. Nuestro objetivo es familiarizar a los/as profesionales de enfermería con la protección radiológica y con el conocimiento de las herramientas y mecanismos de que disponemos, o deberíamos disponer, en nuestros centros asistenciales para aplicarlos desde el punto de vista de protección de la salud. Es importante aclarar que hay disciplinas médicas, diagnósticas o terapéuticas, que utilizan otras radiaciones ionizantes (alfa, beta y gamma), diferentes a las radiaciones X empleadas en radiodiagnóstico. En tal caso, aunque la base sea común, pueden estar sujetas a otras medidas de prevención. Finalmente creemos que de esta manera combatiremos posibles temores y prejuicios en torno a los rayos X; tendremos claras las principales precauciones que podemos tomar y cómo las gestionamos en el desempeño de nuestras funciones diarias como enfermeros/as desde un punto de vista de riesgo laboral.

Verifique sus conocimientos sobre radioprotección

La protección radiológica en radiodiagnóstico merece una atención específica que abordaremos en esta entrega que forma parte de una serie sobre pruebas complementarias que se inició en el Nursing2007 de abril. La utilización de técnicas basadas en el uso de radiación ionizante es muy habitual en nuestro entorno laboral. En estas técnicas intervienen cada vez más profesionales de enfermería, tanto desde un punto de vista de la realización, como de supervisión y de apoyo del médico en su realización. Nuestro objetivo es familiarizar a los/as profesionales de enfermería con la protección radiológica y con el conocimiento de las herramientas y mecanismos de que disponemos, o deberíamos disponer, en nuestros centros asistenciales para aplicarlos desde el punto de vista de protección de la salud. Es importante aclarar que hay disciplinas médicas, diagnósticas o terapéuticas, que utilizan otras radiaciones ionizantes (alfa, beta y gamma), diferentes a las radiaciones X empleadas en radiodiagnóstico. En tal caso, aunque la base sea común, pueden estar sujetas a otras medidas de prevención. Finalmente creemos que de esta manera combatiremos posibles temores y prejuicios en torno a los rayos X; tendremos claras las principales precauciones que podemos tomar y cómo las gestionamos en el desempeño de nuestras funciones diarias como enfermeros/as desde un punto de vista de riesgo laboral.