A mobile bioassay laboratory for the assessment of internal doses based on in vivo and in vitro measurements.

Internal exposures may occur in nuclear power plants, radioisotope production, and in medicine and research laboratories. Such practices require quick response in case of accidents of a wide range of magnitudes. This work presents the design and calibration of a mobile laboratory for the assessment of accidents involving workers and the population as well as for routine monitoring. The system was set up in a truck with internal dimensions of 3.30 m × 1.60 m × 1.70 m and can identify photon emitters in the energy range of 100-3,000 keV in the whole body, organs, and in urine. A thyroid monitor consisting of a lead-collimated NaI(Tl)3" × 3" (7.62 × 7.62 cm) detector was calibrated with a neck-thyroid phantom developed at the IRD (Instituto de Radioproteção e Dosimetria). Whole body measurements were performed with a NaI(Tl)8" × 4" (20.32 × 10.16 cm) detector calibrated with a plastic-bottle phantom. Urine samples were measured with another NaI(Tl) 3" × 3" (7.62 × 7.62 cm) detector set up in a steel support. Standard solutions were provided by the National Laboratory for Metrology of Ionizing Radiation of the IRD. Urine measurements are based on a calibration of efficiency vs. energy for standard volumes. Detection limits were converted to minimum committed effective doses for the radionuclides of interest using standard biokinetic and dosimetric models in order to evaluate the applicability and limitations of the system. Sensitivities for high-energy activation and fission products show that the system is suitable for use in emergency and routine monitoring of individuals under risk of internal exposure by such radionuclides.

Methylmalonate inhibits succinate-supported oxygen consumption by interfering with mitochondrial succinate uptake.

The effect of methylmalonate (MMA) on mitochondrial succinate oxidation has received great attention since it could present an important role in energy metabolism impairment in methylmalonic acidaemia. In the present work, we show that while millimolar concentrations of MMA inhibit succinate-supported oxygen consumption by isolated rat brain or muscle mitochondria, there is no effect when either a pool of NADH-linked substrates or N,N,N',N'-tetramethyl-p-phenylendiamine (TMPD)/ascorbate were used as electron donors. Interestingly, the inhibitory effect of MMA, but not of malonate, on succinate-supported brain mitochondrial oxygen consumption was minimized when nonselective permeabilization of mitochondrial membranes was induced by alamethicin. In addition, only a slight inhibitory effect of MMA was observed on succinate-supported oxygen consumption by inside-out submitochondrial particles. In agreement with these observations, brain mitochondrial swelling experiments indicate that MMA is an important inhibitor of succinate transport by the dicarboxylate carrier. Under our experimental conditions, there was no evidence of malonate production in MMA-treated mitochondria. We conclude that MMA inhibits succinate-supported mitochondrial oxygen consumption by interfering with the uptake of this substrate. Although succinate generated outside the mitochondria is probably not a sig-nificant contributor to mitochondrial energy generation, the physiopathological implications of MMA-induced inhibition of substrate transport by the mitochondrial dicarboxylate carrier are discussed.

Efeitos de Beauveria bassiana (Bals) Vuill e Metarhizium anisopliae (Metsc) Sorok sobre fêmeas ingurgitadas de Amblyomma cajennense (Fabricius, 1787) em condições de laboratório / Effects of Beauveria bassiana (Bals) Vuill and Metarhizium anisopliae (Metsc) Sorok on engorged females of Amblyomma cajennense (Fabricius, 1787) in laboratory conditions

The in vitro susceptibility of Amblyomma cajennense engorged females to some isolated of the fungus Beauveria bassiana and Metarhizium anisopliae was verified and lethal concentrations (LC 50 and LC 90) were calculated. The females were dived in conidia suspensions for five minutes, and kept in climatically controlled chambers BOD under 27º C and 80 por cento relative humidity. Each bioassay had four treatments in concentrations of 105,106,107 e 108 conidia/ml. A control group was also used. The following characteristics were evaluated: weight and period of oviposition, indexes of reproductive and nutritional efficiency and percentage of microbiological control. A dose dependent negative effect was observed in ticks treated with the suspension. All isolates tested cause a negative effect on in vitro tests of engorged females of A. cajennense, suggesting its potential for microbiological control of tick's species.

Efeitos de Beauveria bassiana (Bals) Vuill e Metarhizium anisopliae (Metsc) Sorok sobre fêmeas ingurgitadas de Amblyomma cajennense (Fabricius, 1787) em condições de laboratório / Effects of Beauveria bassiana (Bals) Vuill and Metarhizium anisopliae (Metsc) Sorok on engorged females of Amblyomma cajennense (Fabricius, 1787) in laboratory conditions

The in vitro susceptibility of Amblyomma cajennense engorged females to some isolated of the fungus Beauveria bassiana and Metarhizium anisopliae was verified and lethal concentrations (LC 50 and LC 90) were calculated. The females were dived in conidia suspensions for five minutes, and kept in climatically controlled chambers BOD under 27° C and 80% relative humidity. Each bioassay had four treatments in concentrations of 105,106,107e108 conidia/ml. A control group was also used. The following characteristics were evaluated: weight and period of oviposition, indexes of reproductive and nutritional efficiency and percentage of microbiological control. A dose dependent negative effect was observed in ticks treated with the suspension. All isolates tested cause a negative effect on in vitro tests of engorged females of A. cajennense, suggesting its potential for microbiological control of tick's species.(AU)

Requirements for authorisation of internal dosimetry services.

In order to ensure that a facility is in compliance with the occupational exposure requirements established by regulatory authorities, the measurements and dose assessments specified in the individual monitoring programme need to be reliable. There are two important questions that shall be addressed here: one is how the licensed facilities can demonstrate to their workers and regulatory bodies compliance with the regulatory limits and the reliability of the results of the individual monitoring programmes; the other concerns the mechanisms used to demonstrate to a facility in another country the reliability of the measurement results of an individual monitoring bioassay programme. The accreditation of the bioassay laboratory, according to ISO/IEC 17025, shall be the basic requirement for obtaining the authorisation granted by the national regulatory authority. For the second question, such confidence can be achieved through International Laboratory Accreditation Cooperation (ILAC).

Açäo in vitro dos fungos Beauveria bassiana (Bals) Vuill e Metarhizium anisopliae (Metsch) Sorok sobre ninfas e adultos de Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) / In vitro of the fungi Beauveria bassiana (Bals) Vuill and Metarhizium anisopliae (Metsch) Sorok on ninphs and adults of Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae)

O trabalho teve por objetivo verificar a mortalidade in vitro de ninfas e adultos de Amblyomma cajennense frente à açäo de isolados dos fungos Beauveria bassiana e Metharhizium anisopliae. Foram avaliados três isolados de M. anisopliae (959, 319 e E9) e dois de B. bassiana (986 e 747). As suspensöes de conídios foram preparadas a partir de fungos produzidos em meio de arroz, e cada bioensaio foi constituído de quatro tratamentos nas concentraçöes 10 elevado a 5, 10 elevado a 6, 10 elevado a 7, 10 elevado a 8 conídios/ml e um grupo-controle. A análise constou da observaçäo do percentual de mortalidade, 15 dias após o tratamento ou após a ecdise de adultos. Foram observadas diferenças significativas entre os tratamentos quanto à mortalidade para todos os isolados e todos os instares. Nos grupos tratados houve aumento considerável na mortalidade à medida que se aumentava a concentraçäo de conídios na suspensäo. Conclui-se que todos os isolados testados causaram mortalidade em testes in vitro sobre esses estádios evolutivos, sugerindo o controle do A. cajennense pela açäo desses fungos

Exposure of workers in mineral processing industries in Brazil.

The mining, milling and processing of uranium and thorium bearing minerals may result in radiation doses to workers. A preliminary survey pilot program, that included six mines in Brazil (two coal mines, one niobium mine, one nickel mine, one gold mine and one phosphate mine), was launched in order to determine the need to control the radioactive exposure of the mine-workers. Our survey consisted of the collection and analysis of urine samples, complemented by feces and air samples. The concentrations of uranium, thorium and polonium were measured in these samples and compared to background data from family members of the workers living in the same dwelling and from residents from the general population of Rio de Janeiro. The results from the coal mines indicated that the inhalation of radon progeny may be a source of occupational exposure. The workers from the nickel, gold and phosphate mines that were visited do not require a program to control internal radiological doses. The niobium mine results showed that in some areas of the industry exposure to thorium and uranium might occur.

Ação in vitro dos fungos Beauveria bassiana (Bals) Vuill e Metarhizium anisopliae (Metsch) Sorok sobre ninfas e adultos de Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae)

This work aimed at the evaluation of the in vitro susceptibility of Amblyomma cajennense nimphs and adults to isolates of Beauveria bassiana and Metarhizium anisopliae fungi. Three isolates of M. anisopliae (959, 319 e E9) and two of B. bassiana (986 e 747) were used. Conidia suspensions were made from fungi grown up in a rice culture medium and each test consisted of four treated groups (10(5), 10(6), 10(7), 10(8) conidia/ ml) plus a control group. Viability of individuals was assessed 15 days after treatment or after adult ecdisis. Significative differences were found for all treatments and for all stages studied. A large reduction in the viability of ticks was observed, and this effect increased as conidia concentration raised. Based upon the results obtained, it can be concluded that all isolates tested presented an in vitro lethality for the biological stages of A. cajennense evaluated, suggesting a potential use in the biological control of this tick species.

O trabalho teve por objetivo verificar a mortalidade in vitro de ninfas e adultos de Amblyomma cajennense frente à ação de isolados dos fungos Beauveria bassiana e Metarhizium anisopliae. Foram avaliados três isolados de M. anisopliae (959, 319 e E9) e dois de B. bassiana (986 e 747). As suspensões de conídios foram preparadas a partir de fungos produzidos em meio de arroz, e cada bioensaio foi constituído de quatro tratamentos nas concentrações 10(5), 10(6), 10(7), 10(8) conídios/ml e um grupo-controle. A análise constou da observação do percentual de mortalidade, 15 dias após o tratamento ou após a ecdise de adultos. Foram observadas diferenças significativas entre os tratamentos quanto à mortalidade para todos os isolados e todos os instares. Nos grupos tratados houve aumento considerável na mortalidade à medida que se aumentava a concentração de conídios na suspensão. Conclui-se que todos os isolados testados causaram mortalidade em testes in vitro sobre esses estádios evolutivos, sugerindo o controle do A. cajennense pela ação desses fungos.

A biokinetic model for 137Cs.

An improved biokinetic model for 137Cs in humans was developed based on an analysis of data obtained from individuals internally contaminated during an accident in Goiania, Brazil, and other data. Seventeen children (ten girls and seven boys 1-10 y old), ten adolescents (four females and six males), and thirty adults, (fifteen females and fifteen males contaminated in the accident in Goiânia contributed to this study. 137Cs retention was determined through periodic measurements in a whole-body counter. In addition to the data on 137Cs retention from these individuals, data from a study on the metabolism of 137Cs in immature, adult, and aged Beagle dogs and data from the literature were used in the formulation of the 137Cs biokinetic model presented. Mathematically, the retention of cesium is described by three exponential terms, and the retention model is based on a step function of body weight. When the ICRP Publication 56 model for cesium was compared to the model suggested in this paper, it was determined that the ICRP model predicts lower effective doses in 5-y-old children and higher effective doses in infants, adolescents, and adults.

137Cs internal contamination involving a Brazilian accident, and the efficacy of Prussian Blue treatment.

In an accident involving the stealing and breaching of a radiotherapy source in Goiânia, Brazil, 39 individuals had a high level of 137Cs internal contamination. Prussian Blue was used, in doses that varied from 3-10 g d-1 for adults, to enhance the elimination of 137Cs from the body. The total internal committed doses and the effect of Prussian Blue treatment for 15 contaminated adults involved in this accident have been evaluated in this paper. Prussian Blue caused dose reductions in the range of 51-84%, with an average of 71%. This reduction was shown to be independent of the dosage of Prussian Blue. Total internal committed doses were in the range of 4.6 x 10(-3) Gy to 9.7 x 10(-1) Gy for the most-contaminated adults. Data on 137Cs biological half-lives for seven children contaminated in the accident are also presented.

Application of in-vitro bioassay for 137Cs during the emergency phase of the Goiânia accident.

In the Goiânia accident, many individuals suffered external and internal contamination. The screening of internal contamination was done through 137Cs urinary excretion. During the first month after the accident, only in-vitro bioassay procedures were done. Incorporation into the body and committed doses were estimated using age-specific mathematical models correlating these quantities to the 137Cs excreted in urine. The ratio of feces to urine of 137Cs excretion was used to evaluate the effectiveness of the administration of Prussian Blue on removal of 137Cs from the body.