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1.
Phys Rev Lett ; 126(1): 017201, 2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-33480800

RESUMEN

We apply neutron spectroscopy to measure the magnetic dynamics in the S=3/2 magnet ß-CaCr_{2}O_{4} (T_{N}=21 K). The low-energy fluctuations, in the ordered state, resemble large-S linear spin waves from the incommensurate ground state. However, at higher energy transfers, these semiclassical and harmonic dynamics are replaced by an energy and momentum broadened continuum of excitations. Applying kinematic constraints required for energy and momentum conservation, sum rules of neutron scattering, and comparison against exact diagonalization calculations, we show that the dynamics at high-energy transfers resemble low-S one-dimensional quantum fluctuations. ß-CaCr_{2}O_{4} represents an example of a magnet at the border between classical Néel and quantum phases, displaying dual characteristics.

2.
Artículo en Inglés | MEDLINE | ID: mdl-29129757

RESUMEN

The Asian and Citrus longhorned beetles, Anoplophora glabripennis (ALB) and A. chinensis (CLB) respectively, are two closely related invasive species with overlapping native ranges. Although both species have rather similar biological characteristics, they differ in their invasion patterns. ALB shows numerous, but local, outbreaks in urban areas of North-East America, Western and Central Europe, whereas CLB has colonized a large part of Northern Italy. Temperature is pivotal in setting distribution limits of ectotherms. Low temperature may be limiting for larvae since they are the main overwintering stage for both species. To investigate whether differential cold tolerance may contribute to setting the respective limits of the range invaded by each species, we monitored larval metabolic rate before and after exposure to a one-week ecologically relevant moderate cold stress (-2/+2°C, 14/10h). We tested two distinctive fluctuating regimes before the cold exposure to check whether larval acclimation significantly altered their cold tolerance. Survival was high in all conditions for both species. Visual examination showed temporary locomotor inactivity during the stress but respiration rates were not altered after the stress suggesting that larvae could rapidly resume their initial metabolic activity. The respiration rate was globally higher in ALB than in CLB. Together, these results tend to indicate that both species have similar tolerance to the moderate cold stress tested, but also that ALB may be better at maintaining metabolic activity at cold than CLB. These observed differences could affect phenology in both species and in turn their establishment potential.


Asunto(s)
Aclimatación , Frío , Escarabajos/fisiología , Metabolismo Energético , Especies Introducidas , Respiración , Animales , Escarabajos/crecimiento & desarrollo , Escarabajos/metabolismo , Larva/metabolismo , Larva/fisiología , Locomoción
3.
J Econ Entomol ; 109(1): 222-31, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26511982

RESUMEN

The pine weevils that occur in plantations of Pinus spp. in Andean Patagonia of Argentina belong to the species Pissodes castaneus (De Geer), a Eurasian endemic species, according to the identification based on molecular and morphological characters. Sequences of the mitochondrial Cytochrome oxidase subunit I and nuclear genes (28 S rDNA and ITS2) were obtained for individuals of 13 afforestations, covering the entire distribution area of the established populations in the Andean Patagonia of Argentina. Sequence comparison with representative species of the genus (European, North American, and Chinese species) shows that Patagonian specimens are conspecific to those of P. castaneus sequenced from Europe. Phylogenetic analyses indicate that all terminals from Patagonia form a monophyletic unit without evident subclades, eliminating the possibility of existence of more than one species of Pissodes Germar in this area, including cryptic ones. Moreover, the very low genetic divergence between the Patagonian populations suggests that it is plausible that P. castaneus was introduced into Patagonia from just one location. Mitochondrial DNA analysis shows that Patagonian terminals group together with a French haplotype and are clearly separated from other P. castaneus individuals represented in our sample, and reveal that established populations in Andean Patagonia originated via a limited introduction.


Asunto(s)
ADN Espaciador Ribosómico/genética , Complejo IV de Transporte de Electrones/genética , Proteínas de Insectos/genética , ARN Ribosómico 28S/genética , Gorgojos/fisiología , Animales , Argentina , Núcleo Celular/genética , ADN Mitocondrial/genética , Especies Introducidas , Datos de Secuencia Molecular , Filogenia , Filogeografía , Dinámica Poblacional , Alineación de Secuencia , Análisis de Secuencia de ADN , Gorgojos/genética
4.
Phys Rev Lett ; 110(8): 084101, 2013 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-23473149

RESUMEN

We derive expressions for the probability distribution of the ratio of two consecutive level spacings for the classical ensembles of random matrices. This ratio distribution was recently introduced to study spectral properties of many-body problems, as, contrary to the standard level spacing distributions, it does not depend on the local density of states. Our Wigner-like surmises are shown to be very accurate when compared to numerics and exact calculations in the large matrix size limit. Quantitative improvements are found through a polynomial expansion. Examples from a quantum many-body lattice model and from zeros of the Riemann zeta function are presented.

6.
Rev Med Interne ; 2023 Nov 08.
Artículo en Francés | MEDLINE | ID: mdl-37949692

RESUMEN

Amatoxin-containing mushroom poisoning occurs after consumption of certain mushroom species, of the genera Amanita, Lepiota and Galerina. Amanita phalloides is the most implicated species, responsible for over more than 90% of mushroom-related deaths. The α-amanitin is responsible for most of the observed effects. Symptoms are characterized by severe delayed gastrointestinal disorders (more than six hours after ingestion). The liver being the main target organ, outcome is marked by an often severe hepatitis which can evolve towards terminal liver failure, justifying orthotopic liver transplantation. Acute renal failure is common. Diagnosis of amatoxin-containing mushroom poisoning is based primarily on clinical data; it can be biologically confirmed using detection of amatoxins, especially from urine samples. In the absence of an antidote, early hospital management is essential. It is based on supportive care (early compensation of hydroelectrolytic losses), gastrointestinal digestive decontamination, elimination enhancement, amatoxin uptake inhibitors and antioxidant therapy. Combined therapy associating silibinin and N-acetylcysteine is recommended. Prognosis of this severe poisoning has greatly benefited from improved resuscitation techniques. Mortality is currently less than 10%. In the event of a suspected or confirmed case, referral to a Poison Control Center is warranted in order to establish the diagnosis and guide the medical management of patients in an early and appropriate way.

7.
Chemosphere ; 328: 138487, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37004825

RESUMEN

Ombrotrophic peatlands are fed uniquely by atmospheric inputs and therefore have much potential as temporal archives of atmospheric microplastic (MP) deposition, yet the recovery and detection of MP within an almost purely organic matrix is challenging. This study presents a novel peat digestion protocol using sodium hypochlorite (NaClO) as a reagent for biogenic matrix removal. NaClO is more efficient than hydrogen peroxide (H2O2). By using purged air-assisted digestion, NaClO (50 vol%) reached 99% matrix digestion compared with 28% and 75% by H2O2 (30 vol%) and Fenton's reagent, respectively. At a concentration of 50 vol% NaClO did however chemically disintegrate small amounts (<10 mass %) of polyethylene terephthalate (PET) and polyamide (PA) fragments in the millimeter size range. Observation of PA6 in natural peat samples, while not found in the procedural blanks, questions whether PA is fully disintegrated by NaClO. The protocol was applied to three commercial sphagnum moss test samples, in which MP particles in the range of 0.8-65.4 µm were detected by Raman microspectroscopy. The MP mass% was determined at 0.012% corresponding to 129 thousand MP particles/g, of which 62% were smaller than 5 µm and 80% were smaller than 10 µm, yet were accountable for only 0.4% (500 ng) and 3.2% (4 µg) of the total mass of MP, respectively. These findings underline the importance of the identification of particles Ø < 5 µm when investigating atmospheric MP deposition. The MP counts were corrected for MP recovery loss and procedural blank contamination. MP spike recovery following the full protocol was estimated at 60%. The protocol offers an efficient way of isolating and pre-concentrating most aerosol sized MPs in large quantities of refractory vegetal matrices and enables the automated µRaman scanning of thousands of particles at a spatial resolution on the order of 1 µm.


Asunto(s)
Microplásticos , Contaminantes Químicos del Agua , Microplásticos/química , Plásticos , Peróxido de Hidrógeno , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente , Nylons , Suelo
8.
Rev Med Interne ; 44(9): 487-494, 2023 Sep.
Artículo en Francés | MEDLINE | ID: mdl-37005098

RESUMEN

The word "licorice" refers to the plant, its root, and its aromatic extract. From a commercial point of view, Glycyrrhiza glabra is the most important species with a wide range of uses (herbal medicine, tobacco industry, cosmetics, food and pharmaceutical). Glycyrrhizin is one of the main constituents of licorice. Glycyrrhizin is hydrolyzed in the intestinal lumen by bacterial ß-glucuronidases to 3ß-monoglucuronyl-18ß-glycyrrhetinic acid (3MGA) and 18ß-glycyrrhetinic acid (GA), which are metabolized in the liver. Plasma clearance is slow due to enterohepatic cycling. 3MGA and GA can bind to mineralocorticoid receptors with very low affinity, and 3MGA induces apparent mineralocorticoid excess syndrome through dose-dependent inhibition of 11ß-hydroxysteroid dehydrogenase type 2 in renal tissue. The cases of apparent mineralocorticoid excess syndrome reported in the literature are numerous and sometimes severe, even fatal, most often in cases of chronic high dose consumption. Glycyrrhizin poisonings are characterized by hypertension, fluid retention, and hypokalemia with metabolic alkalosis and increased kaliuresis. Toxicity depends on the dose, the type of product consumed, the mode of consumption (acute or chronic) and a very large inter-individual variability. The diagnosis of glycyrrhizin-induced apparent mineralocorticoid excess syndrome is based on the history, clinical examination, and biochemical analysis. Management is primarily based on symptomatic care and stopping licorice consumption.


Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Ácido Glicirretínico , Glycyrrhiza , Síndrome de Exceso Aparente de Mineralocorticoides , Humanos , Ácido Glicirrínico/efectos adversos , Ácido Glicirrínico/química , Ácido Glicirrínico/metabolismo , Síndrome de Exceso Aparente de Mineralocorticoides/inducido químicamente , Ácido Glicirretínico/efectos adversos , Ácido Glicirretínico/metabolismo , Glycyrrhiza/efectos adversos , Glycyrrhiza/química , Glycyrrhiza/metabolismo
9.
Child Care Health Dev ; 37(6): 866-74, 2011 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22007987

RESUMEN

BACKGROUND: Adolescents and young adults with spina bifida are an at-risk population because of the complexity of their condition, developmental stage and social challenges. The purpose of this qualitative study was to examine the transition to adulthood in young adults with spina bifida and to explore condition-related needs and life skills required during the transition process. METHODS: This qualitative study using narrative inquiry was part of a larger multi-site study of adaptation in young adults with spina bifida. Interviews were completed with 10 participants ranging in age from 18 to 25 years. The guided interview questions focused on specific dimensions of the transition experience related to the ecological model: self-management, independence and inner strength. RESULTS: Three themes capturing different dimensions of the young adults' transition experiences emerged in the analysis. The themes included: (1) Struggling for independence, (2) Limiting social interactions and experiences with stigma, and (3) Building inner strength. CONCLUSION: The qualitative study contributes to a better understanding of the challenges of transition to achieve self-management and social development for young adults with spina bifida. Findings in the life stories highlighted issues that necessitate increased advocacy and interventions from professionals within the health and social system.


Asunto(s)
Adaptación Psicológica , Vida Independiente/psicología , Meningomielocele/terapia , Autocuidado/psicología , Transición a la Atención de Adultos , Adolescente , Adulto , Factores de Edad , Enfermedad Crónica , Femenino , Humanos , Relaciones Interpersonales , Entrevista Psicológica , Masculino , Meningomielocele/psicología , Narración , Prejuicio , Investigación Cualitativa , Medición de Riesgo , Estrés Psicológico , Factores de Tiempo , Adulto Joven
10.
Environ Sci Technol Lett ; 8(11): 954-960, 2021 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-34778488

RESUMEN

Ombrotrophic peatland-fed solely from atmospheric deposition of nutrients and precipitation-provide unique archives of atmospheric pollution and have been used to illustrate trends and changes in atmospheric trace element composition from the recent decadal to the Holocene period. With the acknowledgment of atmosphere plastic pollution, analysis of ombrotrophic peat presents an opportunity to characterize the historical atmospheric microplastic pollution prevalence. Ombrotrophic peatland is often located in comparatively pristine mountainous and boreal areas, acting as sentinels of environmental change. In this paired site study, a Sphagnum ombrotrophic peat record is used for the first time to identify the trend of atmospheric microplastic pollution. This high altitude, remote location ombrotrophic peat archive pilot study identifies microplastic presence in the atmospheric pollution record, increasing from <5(±1) particles/m2/day in the 1960s to 178(±72) particles/m2/day in 2015-2020 in a trend similar to the European plastic production and waste management. Compared to this catchment's lake sediment archive, the ombrotrophic peat core appears to be effective in collecting and representing atmospheric microplastic deposition in this remote catchment, collecting microplastic particles that are predominantly ≤20 µm. This study suggests that peat records may be a useful tool in assessing the past quantities and trends of atmospheric microplastic.

11.
Nat Commun ; 12(1): 7242, 2021 12 21.
Artículo en Inglés | MEDLINE | ID: mdl-34934062

RESUMEN

The emerging threat of atmospheric microplastic pollution has prompted researchers to study areas previously considered beyond the reach of plastic. Investigating the range of atmospheric microplastic transport is key to understanding the global extent of this problem. While atmospheric microplastics have been discovered in the planetary boundary layer, their occurrence in the free troposphere is relatively unexplored. Confronting this is important because their presence in the free troposphere would facilitate transport over greater distances and thus the potential to reach more distal and remote parts of the planet. Here we show evidence of 0.09-0.66 microplastics particles/m3 over 4 summer months from the Pic du Midi Observatory at 2877 meters above sea level. These results exhibit true free tropospheric transport of microplastic, and high altitude microplastic particles <50 µm (aerodynamic diameter). Analysis of air/particle history modelling shows intercontinental and trans-oceanic transport of microplastics illustrating the potential for global aerosol microplastic transport.

12.
Sci Rep ; 11(1): 14464, 2021 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-34262124

RESUMEN

Stromboli Volcano is well known for its persistent explosive activity. On July 3rd and August 28th 2019, two paroxysmal explosions occurred, generating an eruptive column that quickly rose up to 5 km above sea level. Both events were detected by advanced local monitoring networks operated by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and Laboratorio di Geofisica Sperimentale of the University of Firenze (LGS-UNIFI). Signals were also recorded by the Italian national seismic network at a range of hundreds of kilometres and by infrasonic arrays up to distances of 3700 km. Using state-of-the-art propagation modeling, we identify the various seismic and infrasound phases that are used for precise timing of the eruptions. We highlight the advantage of dense regional seismo-acoustic networks to enhance volcanic signal detection in poorly monitored regions, to provide timely warning of eruptions and reliable source amplitude estimate to Volcanic Ash Advisory Centres (VAAC).

13.
Sci Total Environ ; 737: 138699, 2020 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-32376094

RESUMEN

A recent paper by Miszczak et al. (2020) examines metal contamination of mires in Poland and Norway. The authors conclude that lead (Pb) records in ombrotrophic peatlands cannot be used to reconstruct the chronological history of anthropogenic activities due to post-depositional mobility of the metal. We contest this general conclusion which stands in contrast with a significant body of literature demonstrating that Pb is largely immobile in the vast majority of ombrotrophic peatlands. Our aim is to reaffirm the crucial contribution that peat records have made to our knowledge of atmospheric Pb contamination. In addition, we reiterate the necessity of following established protocols to produce reliable records of anthropogenic Pb contamination in environmental archives.

14.
J Environ Radioact ; 100(1): 9-16, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19013695

RESUMEN

An 80-year soil archive, the 42-plot experimental design at the INRA in Versailles (France), is used here to study long-term contamination by 137Cs atmospheric deposition and the fate of this radioisotope when associated with various agricultural practices: fallow land, KCl, NH4(NO3), superphosphate fertilizers, horse manure and lime amendments. The pertinence of a simple box model, where radiocaesium is supposed to move downward by convectional mechanisms, is checked using samples from control plots which had been neither amended, nor cultivated since 1928. This simple model presents the advantage of depending on only two parameters: alpha, a proportional factor allowing the historical atmospheric 137Cs fluxes to be reconstructed locally, and k, an annual loss coefficient from the plow horizon. Another pseudo-unknown is however necessary to run the model: the shape of historical 137Cs deposition, but this function can be easily computed by merging several curves previously established by other surveys. A loss of approximately 1.5% per year from the plow horizon, combined with appropriate fluxes, provides good concordance between simulated and measured values. In the 0-25cm horizon, the residence half time is found to be approximately 18yr (including both migration and radioactive decay). Migration rate constants are also calculated for some plots receiving continuous long-term agricultural treatments. Comparison with the control plots reveals significant influence of amendments on 137Cs mobility in these soils developed from a unique genoform.


Asunto(s)
Agricultura , Cesio/química , Fertilizantes/análisis , Contaminantes Radiactivos del Suelo/química , Suelo/análisis , Radioisótopos de Cesio/química , Modelos Químicos , Factores de Tiempo
15.
J Environ Radioact ; 99(4): 680-93, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17996340

RESUMEN

Soils have been sampled in the vicinity of the Tomsk-Seversk facility (Siberia, Russia) that allows us to measure radioactive contaminations due to atmospheric and aquatic releases. Indeed soils exhibit large inventories of man-made fission products including 137Cs (ranging from 33,000 to 68,500 Bq m(-2)) and actinides such as plutonium (i.e. 239+240Pu from 420 to 5900 Bq m(-2)) or 241Am (160-1220 Bq m(-2)). Among all sampling sites, the bank of the Romashka channel exhibits the highest radioisotope concentrations. At this site, some short half-life gamma emitters were detected as well indicating recent aquatic discharge in the channel. In comparison, soils that underwent atmospheric depositions like peat and forest soils exhibit lower activities of actinides and 137Cs. Soil activities are too high to be related solely to global fallout and thus the source of plutonium must be discharges from the Siberian Chemical Combine (SCC) plant. This is confirmed by plutonium isotopic ratios measured by ICP-MS; the low 241Pu/239Pu and 240Pu/239Pu atomic ratios with respect to global fallout ratio or civil nuclear fuel are consistent with weapons grade signatures. Up to now, the influence of Tomsk-Seversk plutonium discharges was speculated in the Ob River and its estuary. Isotopic data from the present study show that plutonium measured in SCC probably constitutes a significant source of plutonium in the aquatic environment, together with plutonium from global fallout and other contaminated sites including Tomsk, Mayak (Russia) and Semipalatinsk (Republic of Kazakhstan). It is estimated that the proportion of plutonium from SCC source can reach 45% for 239Pu and 60% for 241Pu in the sediments.


Asunto(s)
Centrales Eléctricas , Monitoreo de Radiación/métodos , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisis , Americio/análisis , Radioisótopos de Cesio/análisis , Geografía , Kazajstán , Plutonio/análisis , Ceniza Radiactiva , Liberación de Radiactividad Peligrosa , Contaminantes Radiactivos/análisis , Radioisótopos , Federación de Rusia , Suelo/análisis
16.
Clin Toxicol (Phila) ; 56(8): 790-794, 2018 08.
Artículo en Inglés | MEDLINE | ID: mdl-29323540

RESUMEN

CONTEXT: Among the numerous varieties of squash that exist, some are edible while other bitter-tasting ones are not fit for human consumption. Cases of confusion seem to be multiplying and are characterized by digestive problems (diarrhea, vomiting, and abdominal pain). METHODS: This is a descriptive retrospective study of cases of exposure reported to French Poison Control Centers between 1 January 2012 and 12 December 2016. RESULTS: 353 patients were included, with 71.7% belonging to collective cases of poisoning. The male to female sex ratio was 0.75 for an average age of 38.2 ± 23.6 years. The circumstances of exposure were dietary for 337 patients (95.5%). The majority of the squash consumed was purchased at a store (55.8%) but some also came from the garden (25.5%). 204 patients (57.8%) mostly presented with diarrhea, vomiting, abdominal pain, sometimes with the consequent dehydration, hypotension, tachycardia, headaches, or vertigo. There were no deaths or severe (Poisoning Severity Score (PSS) 3) cases, but there were 14 patients (4.0%) of moderate severity, 190 patients (53.8%) of minor severity (PSS 1), and 149 patients (42.2%) without severity (PSS 0) but among which we include the bitter taste of the squash. The average age of PSS 2 patients was significantly (p = .003) older than that of the PSS <2 patients. CONCLUSION: As the first consequential series in Europe, our study shows that exposure to non-edible squash is frequent. Usually benign, poisoning could be the consequence of the irritating effect of certain cucurbits, the molecules responsible for the taste and toxicity of the fruits. In terms of prevention therefore, we recommend disposing of any squash with a bitter taste.


Asunto(s)
Cucurbita/envenenamiento , Frutas/envenenamiento , Centros de Control de Intoxicaciones/estadística & datos numéricos , Intoxicación/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Francia/epidemiología , Humanos , Lactante , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Adulto Joven
17.
Orthop Traumatol Surg Res ; 103(4): 597-601, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28373140

RESUMEN

INTRODUCTION: Acute quadriceps tendon rupture is rare. The gold-standard repair technique is transosseous patellar suture. Biomechanical studies have validated the use of anchors as an alternative. The present study sought to report long-term clinical and radiological results in a series of acute quadriceps tendon rupture repaired with anchors. The study hypothesis was that results are comparable to those of the gold-standard technique. METHODS: A retrospective continuous study included 25 knees with acute quadriceps tendon rupture, operated on by a single surgeon between 2007 and 2013: 22 patients; 17 males, 5 females; mean age, 64 years (range: 52-87 years). Modified Bunnell suture was performed, using either 2 anchors (19 knees) or 3 anchors (6 knees). Anchors were positioned under 20° flexion. The factors studied were: active range of motion, muscle strength, patient satisfaction, Lysholm score, return to work, and the radiological behavior of the anchors. RESULTS: At a mean follow-up of 7 years (range: 3-9 years), all but 1 patient had 0° active extension. Mean active flexion was 128° (range: 110-150°), and mean muscle strength was 4.9/5. Mean Lysholm score was 92. Subjective results proved satisfactory or very satisfactory in 23 cases. Working patients returned to work at a mean 4.2 months. There were no cases of anchor migration or of re-rupture. One poorly tolerated anchor was ablated at 2 years, without functional impact. CONCLUSION: Outcomes with anchors were comparable to those of the gold-standard technique. Anchors allow immediate rehabilitation, without risk of anchor migration. The technique provided satisfactory functional recovery. LEVEL OF EVIDENCE: IV, retrospective cohort study.


Asunto(s)
Músculo Cuádriceps/cirugía , Anclas para Sutura , Traumatismos de los Tendones/cirugía , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Rango del Movimiento Articular , Estudios Retrospectivos , Rotura/cirugía , Resultado del Tratamiento
18.
J Environ Radioact ; 227: 106499, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33307329
19.
Sci Total Environ ; 566-567: 238-249, 2016 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-27220101

RESUMEN

The purpose of this study is to evaluate the contamination in As, Ba, Co, Cu, Mn, Ni, Sr, V, Zn and REE, in a high uranium activity (up to 21,000Bq∙kg(-1)) area, downstream of a former uranium mine. Different geochemical proxies like enrichment factor and fractions from a sequential extraction procedure are used to evaluate the level of contamination, the mobility and the availability of the potential contaminants. Pb isotope ratios are determined in the total samples and in the sequential leachates to identify the sources of the contaminants and to determine the mobility of radiogenic Pb in the context of uranium mining. In spite of the large uranium contamination measured in the soils and the sediments (EF≫40), trace element contamination is low to moderate (2

Asunto(s)
Sedimentos Geológicos/análisis , Radioisótopos de Plomo/análisis , Minería , Contaminantes del Suelo/análisis , Oligoelementos/análisis , Monitoreo del Ambiente , Francia , Uranio
20.
Oncogene ; 20(10): 1186-92, 2001 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-11313862

RESUMEN

Thyrotropin (TSH) stimulates survival and growth of thyroid cells via a seven transmembrane G protein-coupled receptor. TSH elevates the intracellular cyclic AMP (cAMP) levels activating protein kinase A (PKA). Recent evidence indicates that p21 Ras is required for TSH-induced mitogenesis, but the molecular mechanism(s) is not known. Here we report that Ras p21 activity is necessary for the Go- G1 transition in TSH induced cycle and that the downstream effector of Ras upon TSH signaling is p85-p110 PI3K. We show that PI3K inhibitors block TSH-induced DNA synthesis, cAMP-PKA stimulate the formation of the complex PI3K-p21 Ras and reduce the complex Ras-Raf1 in thyroid and other cells types. Moreover, PKA phosphorylates immunoprecipitated p85 and PKA phosphorylation of cell extracts significantly stimulates the formation of the complex PI3K-Ras. We suggest that PKA phosphorylates p85 and stabilizes the complex p110-p85, enhancing the interaction PI3K and p21 Ras. Simultaneously, cAMP inhibits Raf-1-ERK signaling by decreasing Raf1 availability to Ras. Under these circumstances PI3K signaling is favored. These results indicate that PI3K is an important mediator of Ras effects in cAMP-induced proliferation and illustrates how cAMP can selectively influence Ras effector pathways.


Asunto(s)
Ciclo Celular/efectos de los fármacos , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Transducción de Señal , Tiroglobulina/metabolismo , Proteínas ras/metabolismo , Diferenciación Celular , División Celular/fisiología , Línea Celular , ADN/metabolismo , Proteínas de Unión al GTP/metabolismo , Immunoblotting , Proteína Oncogénica p21(ras)/metabolismo , Fosfatidilinositol 3-Quinasas/fisiología , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-raf/metabolismo , Tiroglobulina/genética , Proteínas ras/genética
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