Indoor radon risk mapping of the Canary Islands using a methodology for volcanic islands combining geological information and terrestrial gamma radiation data.

Within the framework of the recent approval of the National Plan Against Radon by the Council of Ministers of the Spanish Government, one of its five axes focuses on the delimitation of priority action areas. In line with this objective, this paper presents the indoor radon risk maps of the Canary Islands. Due to the volcanic origin of the Canary Islands, there is a great deal of geological heterogeneity in the soils on which buildings settle, making it very difficult to delimit radon-risk areas in the process of creating maps. Following a methodology developed in previous works for a study area formed of a set of representative municipalities, this paper presents radon risk maps of the Canary Islands based on lithostratigraphic information and high-resolution terrestrial gamma radiation maps. The goodness of fit of these maps is verified based on a statistical analysis of indoor radon concentration measurements carried out at representative building enclosures. In order to analyse the level of risk to the population, these maps were combined with built up areas (urban fabric) maps and estimations of the annual effective doses due to radon was obtained by applying a dosimetric model. This methodology improves the capability to delimit indoor radon risk areas, with a greater margin of safety. In this respect, it is estimated that areas classified as low risk have indoor radon concentrations 41 % below the current reference level of 300 Bq/m3 established by national regulations in compliance with the precepts laid down in the European EURATOM Directive.

Multiparametric analysis for the determination of radon potential areas in buildings on different soils of volcanic origin.

The transposition of the European EURATOM directive into the regulations of the different member states of the European Union involved governments making great efforts to define priority action maps against indoor radon exposure in buildings over a short time period. In Spain, the Technical Building Code established 300 Bq/m3 as a reference level and set up a classification of municipalities in which remediation measures should be adopted for radon exposure in buildings. Oceanic volcanic islands, such as the Canary Islands, present high geological heterogeneity in a small space due to their volcanic origin. This variability poses a challenge to the elaboration of radiological risk maps, which makes it necessary to have a high density of data to collect local variations. This paper presents a methodology to obtain accurate radon risk maps based on geological criteria and terrestrial gamma radiation. The predictive efficiency of these maps is statistically verified using indoor radon concentration data measured in buildings. Other radiological variables, which are commonly used as criteria for radon risk prediction found in the literature, were also applied, such as the geogenic radon potential and the activity concentration of natural radioisotopes in soils. The higher resolution of the maps obtained allows for a more detailed classification of radon risk zones in the study area than the current risk maps published in the Spanish building regulations.

Methodology for determination of radon prone areas combining the definition of a representative building enclosure and measurements of terrestrial gamma radiation.

The recommendations of the European Atomic Energy Community (EURATOM) have recently been incorporated into Spanish regulations in the Basic Document of Health Standards of the Technical Building Code (CTE), section HS6, on protection against radon exposure. This further accentuates the need to delimit radon prone areas as a strategy to address measures which minimise the effects of this gas on the population. In this research, measurements of terrestrial gamma radiation and indoor radon of dwellings have been carried out in the same location to delimit these risk areas. A new methodology has been developed including a definition of a Representative Building Enclosure (RBE) and it is proposed a Building Storey Index (IBS) which allows normalizing measurements of indoor radon activity concentration taken in different levels from the ground to the RBE. The results show the need to consider the type of contact that exists between the building and the ground as a determining factor of radon risk. Terrestrial gamma radiation is used as a proxy for radioisotopic composition of soils to characterise the indoor radon risk at different geological formation.

Assessment of radon risk areas in the Eastern Canary Islands using soil radon gas concentration and gas permeability of soils.

The Basic Safety Standard (BSS) Directive 2013/59/EURATOM of the European Union (EU) has stated the need for member states to establish national action plans to mitigate their general population's long-term risks of exposure to radon gas. Maps of radon-prone areas provide a useful tool for the development of such plans. This paper presents the maps of radon-prone areas in the Eastern Canary Islands (Gran Canaria, Fuerteventura and Lanzarote) obtained from assessment of Geogenic Radon Potential (GRP) distribution in the territory. GRP constitutes a magnitude that is contingent on both radon activity concentration and gas permeability of soils. An extensive campaign covering all geological formations of the Eastern Canary Islands was undertaken to locally sample these parameters. Geostatistical analysis of the spatial distribution of radon concentration in soils, permeability and GRP was performed on each of the islands, and the relationship between these magnitudes and the characteristic geological formations of the volcanic islands was investigated. Areas dominated by basic volcanic and plutonic rocks (originated by both recent and ancient volcanism) exhibit relatively low levels of radon in soils, and with the exception of specific cases of very high permeability, these areas are not classified as prone to radon risk according to international criteria. Areas in which intermediate or acidic volcanic and plutonic rocks predominate are characterised by greater radon activity concentration in soils, rendering them radon-prone. Given these results, Lanzarote is classified as an island with low radon risk all over its surface; Fuerteventura presents low-medium risk; and Gran Canaria contains extensive areas in the centre and north where the risk is medium or high. This classification is consistent with the risk maps obtained by National and European agencies from indoor radon measurements conducted on these islands.

Natural radioactivity in algae arrivals on the Canary coast and dosimetry assessment.

Nowadays, the use of wild and culture harvest seaweed in food industry is a booming productive sector. In this context, a radiological characterization of five globally common seaweed species that were collected in arrival on Gran Canaria coast was carried out. The studied algae species were Cymopolia barbata, Lobophora variegata, Sargassum vulgare, Dictyota dichotoma and Haliptilon virgatum. Radionuclides analysed by alpha and gamma spectrometry were 238U, 234U, 235U, 210Po, 234Th, 226Ra, 210Pb, 228Th, 224Ra, 40K and 7Be. Activity concentrations, ratios, and concentration factors (CF) were determined for all samples collected. The CF in algae was higher for reactive-particle radionuclides (210Po, 234Th, 228Th and 210Pb) than for conservative ones (40K and the uranium isotopes). 210Po, 228Th and 234Th CF were one or two orders of magnitude higher than those recommended by the IAEA. L. variegata, C. barbata and S. vulgare showed a clear preference for 210Pb and 210Po, for uranium radioisotopes, and for 40K and 234Th, respectively. A dosimetry assessment due to seaweed ingestion showed considerable values of annual committed effective dose for H. virgatum (605 ±â€¯19 µSv/y), L. variegata (574 ±â€¯17 µSv/y) and D. dichotoma (540 ±â€¯30 µSv/y). Hence, this study suggests that an algae radiological characterization is recommended as part of the product valorising process.

Mapping natural radioactivity of soils in the eastern Canary Islands.

The Canary Islands archipielago (Spain) comprises seven main volcanic islands and several islets that form a chain extending for around 500 km across the eastern Atlantic, between latitudes 27°N and 30°N, with its eastern edge only 100 km from the NW African coast. The administrative province of Las Palmas comprises the three eastern Canary Islands (Lanzarote, Fuerteventura and Gran Canaria). An extensive study of terrestrial gamma dose rates in surface soils has been carried out to cover the entire territory of the province (4093 km2). The average outdoor gamma dose rate in air at 1 m above ground is 73 nGyh-1 at Gran Canaria, 32 nGyh-1 at Fuerteventura, and 25 nGyh-1 at Lanzarote. To complete the radiological characterization of this volcanic area, 350 soil samples at 0-5 cm depth were collected to cover all the geologic typologies of the islands. These samples were measured using high resolution gamma spectrometry to determine the activity concentrations of 226Ra, 232Th and 40K. The average values obtained were 25.2 Bq/kg, 28.9 Bq/kg, and 384.4 Bq/kg, respectively. Maps of terrestrial gamma activity, effective dose, and activity concentrations of 226Ra, 232Th and 40K for the region have been developed through the use of geostatistical interpolation techniques. These maps are in accord with the geology of the islands.

A simple methodology for characterization of germanium coaxial detectors by using Monte Carlo simulation and evolutionary algorithms.

The determination in a sample of the activity concentration of a specific radionuclide by gamma spectrometry needs to know the full energy peak efficiency (FEPE) for the energy of interest. The difficulties related to the experimental calibration make it advisable to have alternative methods for FEPE determination, such as the simulation of the transport of photons in the crystal by the Monte Carlo method, which requires an accurate knowledge of the characteristics and geometry of the detector. The characterization process is mainly carried out by Canberra Industries Inc. using proprietary techniques and methodologies developed by that company. It is a costly procedure (due to shipping and to the cost of the process itself) and for some research laboratories an alternative in situ procedure can be very useful. The main goal of this paper is to find an alternative to this costly characterization process, by establishing a method for optimizing the parameters of characterizing the detector, through a computational procedure which could be reproduced at a standard research lab. This method consists in the determination of the detector geometric parameters by using Monte Carlo simulation in parallel with an optimization process, based on evolutionary algorithms, starting from a set of reference FEPEs determined experimentally or computationally. The proposed method has proven to be effective and simple to implement. It provides a set of characterization parameters which it has been successfully validated for different source-detector geometries, and also for a wide range of environmental samples and certified materials.

Trombosis venosa profunda primaria de miembro superior / Primary upper-extremity deep vein thrombosis

No disponible

Natural radioactivity measurements of beach sands in Gran Canaria, Canary Islands (Spain).

Concentrations of natural radionuclides (226)Ra, (232)Th, (40)K and man-made (137)Cs in most important tourist Gran Canaria beaches have been determined using a high-purity Germanium detector to analyse their radiological hazard. Average values of the activity concentrations of (226)Ra, (232)Th and (40)K were 17.6±1.4, 21.3±1.8 and 480±22 Bq kg(-1), respectively. Observed activity concentration values of (137)Cs were practically negligible from a radiological protection point of view. The results of this paper were compared with others published in the bibliography for beaches and coastal sediments of different countries. The mean external air absorbed dose rate was 43.9±2.8 nGyh(-1), which resulted in an outdoor annual effective dose below the world average. Also, the radium equivalent and the external hazard index were calculated. Results from Gran Canaria beaches showed the low levels of radioactivity, indicating no significant radiological risk related to human activities in the area.

Expression of mTert in primary murine cells links the growth-promoting effects of telomerase to transforming growth factor-beta signaling.

Here, we show that ectopic expression of the catalytic subunit of mouse telomerase (mTert) confers a growth advantage to primary murine embryonic fibroblasts (MEFs), which have very long telomeres, as well as facilitates their spontaneous immortalization and increases their colony-forming capacity upon activation of oncogenes. We demonstrate that these telomere length-independent growth-promoting effects of mTert overexpression require catalytically active mTert, as well as the formation of mTert/Terc complexes. The gene expression profile of mTert-overexpressing MEFs indicates that telomerase enhances growth in these cells through the repression of growth-inhibiting genes of the transforming growth factor-beta (TGF-beta) signaling network. We functionally validate this result by showing that mTert abrogates the growth-inhibitory effect of TGF-beta in MEFs, thus demonstrating that telomerase increments the proliferative potential of primary mouse embryonic fibroblasts by targeting the TGF-beta pathway.

The copper-chelating agent, trientine, suppresses tumor development and angiogenesis in the murine hepatocellular carcinoma cells.

Angiogenesis is now recognized as a crucial process in tumor development, including hepatocellular carcinoma (HCC). Since HCC is known as a hypervascular tumor, anti-angiogenesis is a promising approach to inhibit the HCC development. Trientine dihydrochloride (trientine) is used in clinical practice as an alternative copper (Cu)-chelating agent for patients with Wilson's disease of penicillamine intolerance. In our study, we examined the effect of Cu-chelating agents on tumor development and angiogenesis in the murine HCC xenograft model. Although both trientine and penicillamine in the drinking water suppressed the tumor development, trientine exerted a more potent inhibitory effect than penicillamine. In combination with a Cu-deficient diet, both trientine and penicillamine almost abolished the HCC development. Trientine treatment resulted in a marked suppression of neovascularization and increase of apoptosis in the tumor, whereas tumor cell proliferation itself was not altered. In vitro studies also exhibited that trientine is not cytotoxic for the tumor cells. On the other hand, it significantly suppressed the endothelial cell proliferation. These results suggested that Cu plays a pivotal role in tumor development and angiogenesis in the murine HCC cells, and Cu-chelators, especially trientine, could inhibit angiogenesis and enhance apoptosis in the tumor with consequent suppression of the tumor growth in vivo. Since trientine is already used in clinical practice without any serious side effects as compared to penicillamine, it may be an effective new strategy for future HCC therapy.

Chronic in vitro exposure to 3'-azido-2', 3'-dideoxythymidine induces senescence and apoptosis and reduces tumorigenicity of metastatic mouse mammary tumor cells.

Normal cells in culture divide a certain amount of times and undergo a process termed replicative senescence. Telomere loss is thought to control entry into senescence. Activation of telomerase in tumors bypasses cellular senescence and is thus a requirement for tumor progression. We reported previously the preferential incorporation of 3'-azido-2', 3'-dideoxythymidine (AZT) in telomeric sequences of immortalized cells in culture. In this work, we have investigated the effects of chronic in vitro AZT exposure on F3II mouse mammary carcinoma cells. We demonstrate, for the first time, that AZT-treated tumor cells have a reduced tumorigenicity in syngeneic BALB/c mice. Tumor incidence was reduced and survival was prolonged in animals inoculated with AZT-treated cells when comparing with control counterparts. The number and size of spontaneous metastases were also decreased in animals inoculated with AZT-treated cells. In addition, we present evidence of morphological and biochemical signs of senescence, as shown by the staining for senescence associated beta-galactosidase activity, and induction of programmed cell death, as demonstrated by an increase of caspase-3 activity, in tumor cells exposed to AZT. These data indicate that chronic exposure of mammary carcinoma cells to AZT may be sufficient to induce a senescent phenotype and to reduce tumorigenicity.

Irreversible telomere shortening by 3'-azido-2',3'-dideoxythymidine (AZT) treatment.

Telomeres shorten by 30 to 50 bp with each cell division. Germ line, tumor and stem cells overcome progressive shortening by elongating their telomeres with telomerase. Previously we demonstrated that 3'-azido-2',3'-dideoxythymidine (AZT), incorporates into telomeric DNA. To determine if telomeric AZT incorporation was a telomerase mediated phenomenon, we subjected tumor cells to long-term AZT exposure. Here we report the shortening of the telomeric sequences of HeLa cells cultured with 800 microM AZT for 15 passages. Southern blots of HeLa DNA cultured with AZT and digested with SAU 3AI, Alu I, and Rsa I revealed a progressive shortening of the telomeric repeats when probed with a human biotinylated telomeric probe. The shortened telomeric repeats did not elongate after culturing without AZT for an additional 25 passages. No evidence of senescence could be detected.

Fibrin formation induced by tumor procoagulants enhances urokinase activity produced by mammary carcinoma cells.

We have examined the relationship between the procoagulant activity of F3II mouse mammary carcinoma cells and the production of urokinase, a profibrinolytic serine protease involved in tumor invasion and hematogenous metastasis. F3II cells were capable of inducing the conversion of purified fibrinogen to fibrin in the presence of calcium and plasma traces. Immunocytochemical examination of semi-confluent monolayers demonstrated that F3II cells also synthesized high levels of urokinase. Although fibrinogen did not modify profibrinolytic activity produced by F3II monolayers, fibrin formation increased tumor-derived urokinase activity by two-fold. The present data provide new insights into the cooperative role of coagulation and fibrinolysis facilitating and perpetuating tumor invasion.

Inhibition of mammary tumor cell adhesion, migration, and invasion by the selective synthetic urokinase inhibitor B428.

We have analyzed the anti-invasive properties of the selective synthetic urokinase inhibitor 4-iodo benzo[b]thiopene-2-carboxamidine (B428) in the mouse mammary carcinoma model F3II. At non-cytotoxic concentrations (10-20 microM), B428 blocked secreted and cell-associated tumor-derived urokinase activity as well as whole cell plasminogen-dependent casein degradation. Pretreatment of F3II monolayers with B428 enhanced membrane bound uPA, suggesting that the compound may modify urokinase receptor mobilization and urokinase-dependent cell signaling. B428 exerted a dose-dependent inhibition of Matrigel invasion by F3II cells and also reduced tumor cell adhesion and migration using the same doses. Our data indicate that uPA and its cell surface receptor are involved in attachment, migration, and invasion of mammary tumor cells, and that the three processes can be blocked by a synthetic urokinase inhibitor.

[Communication barriers with the HIV+ patient perceived by health personnel]. / Barreras de comunicación con el paciente VIH+ percibidas por el personal sanitario.

The purpose of this study was to identify major communication barriers between health professionals and patients infected with HIV. Information from 17 experts on AIDS across Spain was gathered using the Delphi technique. A total of 24 barriers were identified and compounded into groups in relation to the provider, the patient, the message and the context wherein the communication process takes place. Major communication barriers were associated to the lacking of specific skills on the provider's side and to certain health professional's and patient attitudes towards each other and from both towards some emotional aspects related to AIDS.