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1.
Nat Commun ; 13(1): 2912, 2022 05 25.
Artículo en Inglés | MEDLINE | ID: mdl-35614049

RESUMEN

The primary steps of photosynthesis rely on the generation, transport, and trapping of excitons in pigment-protein complexes (PPCs). Generically, PPCs possess highly structured vibrational spectra, combining many discrete intra-pigment modes and a quasi-continuous of protein modes, with vibrational and electronic couplings of comparable strength. The intricacy of the resulting vibronic dynamics poses significant challenges in establishing a quantitative connection between spectroscopic data and underlying microscopic models. Here we show how to address this challenge using numerically exact simulation methods by considering two model systems, namely the water-soluble chlorophyll-binding protein of cauliflower and the special pair of bacterial reaction centers. We demonstrate that the inclusion of the full multi-mode vibronic dynamics in numerical calculations of linear spectra leads to systematic and quantitatively significant corrections to electronic parameter estimation. These multi-mode vibronic effects are shown to be relevant in the longstanding discussion regarding the origin of long-lived oscillations in multidimensional nonlinear spectra.


Asunto(s)
Clorofila , Complejos de Proteína Captadores de Luz , Clorofila/química , Electrónica , Transferencia de Energía , Complejos de Proteína Captadores de Luz/metabolismo , Proteínas , Análisis Espectral/métodos
2.
Sci Total Environ ; 679: 12-22, 2019 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-31078771

RESUMEN

Pesticides are one of the most frequently anthropogenic xenobiotics detected in water. Among these, the organophosphorus pesticides (OPs) are very widely used in agriculture due to their broad spectrum of activity and their low price, but they also have high potent effects as neurotoxic compounds in non-target organisms. The aim of this study was to evaluate biomarkers acetylcholinesterase (AChE), butyrylcholinesterase (BChE), propionylcholinesterase (PChE) and carboxylesterase (CbE) in the representative Atlantic fish species Trachurus trachurus, Merluccius merluccius and Trisopterus luscus from "Rías Gallegas", a traditional Spanish fishing area. These esterase activities were evaluated in the brain, muscle and liver to determine the most adequate tissue to measure such enzymatic activities. The sensitivity of AChE and CbE activities from different tissues the widely used organophosphorus insecticide chlorpyrifos (CP), and its toxic metabolite (CP-oxon) was also tested. AChE activity was predominant in all tissues of the analysed species (particularly in brain constituting from 78.33%, 89.83% and 88.43% of total ChEs in Trachurus trachurus, Merluccius merluccius and Trisopterus luscus, respectively). Under in vitro exposure, esterases were shown to be highly sensitive to CP and especially to CP-oxon. Moreover, a similar effect observed on AChE and CbE activities could suggest that CbE activity might contribute efficiently against the toxic effects of CP, especially in muscle and the liver. The presence of BChE, PChE and upper CbE activities in muscle and the liver and their OP-sensibilities can be used to study their function in the pesticide biochemical detoxification pathways with a prominent role as a safeguarding mechanism against pesticide toxicity.


Asunto(s)
Cloropirifos/efectos adversos , Esterasas/metabolismo , Proteínas de Peces/metabolismo , Gadiformes/metabolismo , Perciformes/metabolismo , Contaminantes Químicos del Agua/efectos adversos , Animales , Monitoreo del Ambiente , Insecticidas/efectos adversos , Especificidad de Órganos
3.
Comput Methods Programs Biomed ; 175: 129-137, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31104702

RESUMEN

BACKGROUND AND OBJECTIVE: Knowing whether a subject is conscious or not is a current challenge with a deep potential clinical impact. Recent theoretical considerations suggest that consciousness is linked to the complexity of distributed interactions within the corticothalamic system. The fractal dimension (FD) is a quantitative parameter that has been extensively used to analyse the complexity of structural and functional patterns of the human brain. In this study we investigate FD to assess whether it can discriminate between consciousness and different states of unconsciousness in healthy individuals. METHODS: We study 69 high-density electroencephalogram (hd-EEG) measurements after transcranial magnetic stimulation (TMS) in 18 healthy subjects progressing from wakefulness to non-rapid eye movement (NREM) sleep and sedation induced by different anaesthetic agents (xenon and propofol). We quantify the integration of thalamocortical networks by calculating the FD of a spatiotemporal voxelization obtained from the locations of all sources that are significantly activated by the perturbation (4DFD). Moreover, we study the temporal evolution of the evoked spatial distributions and compute a measure of the differentiation of the response by means of the Higuchi FD (HFD). Finally, a Fractal Dimension Index (FDI) of perturbational complexity is computed as the product of both quantities: integration FD (4DFD) and differentiation FD (HFD). RESULTS: We found that FDI is significantly lower in sleep and sedation when compared to wakefulness and provides an almost perfect intra-subject discrimination between conscious and unconscious states. CONCLUSIONS: These results support the combination of FD measures of cortical integration and cortical differentiation as a novel paradigm of tracking complex spatiotemporal dynamics in the brain that could provide further insights into the link between complexity and the brain's capacity to sustain consciousness.


Asunto(s)
Estado de Conciencia , Electroencefalografía , Estimulación Magnética Transcraneal , Inconsciencia , Adolescente , Adulto , Anestesia , Encéfalo/diagnóstico por imagen , Femenino , Fractales , Voluntarios Sanos , Humanos , Masculino , Propofol , Procesamiento de Señales Asistido por Computador , Sueño , Vigilia , Xenón , Adulto Joven
4.
Ecotoxicol Environ Saf ; 164: 493-499, 2018 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-30145489

RESUMEN

Concentrations of 7 different polychlorinated biphenyl (PCB) congeners, and eleven organochlorine pesticides (OCPs) and metabolites, including DDTs (dichlorodiphenyltrichloroethane), HCHs (hexachlorocyclohexane isomers), Endosulfan, Endosulfan sulfate, Endrin, Dieldrin and HCB (hexachlorobenzene), were determined in adipose tissue of 57 yellow-legged gulls collected from NW and N Spain. Furthermore, the possible differences due to two endogenous factors, age and gender, were determined. All the analyzed PCBs were detected in over 66% of the samples, with levels of 291.9 (PCB 180), 34.5 (PCB 118), 0.7 (PCB 28), 432.6 (PCB 153), 225.5 (PCB 138), 1.3 (PCB 101) and 0.4 (PCB 52) µg/kg of adipose tissue. With respect to the OCPs and metabolites, only 4,4'-DDE and HCB were detected in more than 50% of the samples, with means of 360.6 and 2.5 µg/kg of adipose tissue, respectively. From all the considered contaminants, only 4,4'-DDE levels presented significant differences depending on the gender, with females showing higher values than males (p < 0.01). Significant differences (p < 0.001) were also found related to age for the levels of PCBs 180, 138, 101, 28 and 153, as well as 4,4'-DDE, with adult levels being higher than those in young birds. The results of the present study constitute a baseline to better assess the environmental impacts of PCB and OCP contamination at other coastal sites for future biomonitoring studies, with particular emphasis on gender- and age-related differences.


Asunto(s)
Tejido Adiposo/química , Charadriiformes/metabolismo , Contaminantes Ambientales/análisis , Hidrocarburos Clorados/análisis , Bifenilos Policlorados/análisis , Factores de Edad , Animales , DDT/análisis , Monitoreo del Ambiente , Femenino , Hexaclorobenceno/análisis , Hexaclorociclohexano/análisis , Masculino , Plaguicidas/análisis , Factores Sexuales , España
5.
Clin Transl Oncol ; 19(12): 1531-1536, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28718070

RESUMEN

PURPOSE: Recently neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) have been reported to be inflammatory parameters that confer poorer outcome in metastatic castration-resistant prostate cancer (mCPRPC). However, these ratios have not been analyzed in patients treated with abiraterone acetate. We explored the relationship between different values of PLR and NLR and survival in mCPRCP treated with abiraterone and their possible relation with a prostate specific antigen (PSA) response. METHODS: We retrospectively analyzed 101 patients with mCRPC treated with abiraterone from January of 2012 to November of 2015 in two different hospitals. A cut-off value of 5 for NLR and 150 for PLR were used to compare survival by Kaplan-Meier method. Moreover, an association between these cut-off values and the PSA response was analyzed by a χ 2 test. RESULTS: In the case of NLR, the median DFS were 12, 1 months for NLR <5 and 7 months for NLR ≥5, p = 0.061. The median OS were 23.9 months for NLR <5 and 16.3 months for NLR ≥5, p = 0.046. In the case of PLR, the median DFS were 11.8 months for PLR <150 and 10.6 months for PLR ≥150, p = 0.549. The median OS were 27.4 months for PLR <150 and 15.9 months for PLR ≥150, p = 0.005. It was not observed a correlation between the different cut-off values of PLR or NLR and a PSA response ≥25% (p = 0.31). CONCLUSIONS: It is shown a better prognostic relationship between PLR and NLR low values and OS that is statistically significant in mCPRC patients treated with abiraterone. Furthermore, it was not shown a relation between PLR and NLR values and PSA response.


Asunto(s)
Acetato de Abiraterona/uso terapéutico , Antineoplásicos/uso terapéutico , Biomarcadores de Tumor/análisis , Plaquetas/patología , Linfocitos/patología , Neutrófilos/patología , Neoplasias de la Próstata Resistentes a la Castración/patología , Anciano , Anciano de 80 o más Años , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Neoplasias de la Próstata Resistentes a la Castración/sangre , Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Estudios Retrospectivos , Tasa de Supervivencia
6.
Ecotoxicol Environ Saf ; 140: 24-29, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28231502

RESUMEN

The aim of this study was to determine heavy metal reference levels for risk assessment studies. For this purpose, the levels of lead, cadmium, copper and zinc were determined in liver tissues of wild boars sampled in NW Spain. The mean values were 0.383, 0.326, 23.50 and 56.86mg/kg dried weight, respectively. In general, the levels detected were similar to or lower than the levels reported in literature. This study not only provides a useful baseline for biomonitoring the levels of the analyzed contaminants in wildlife in NW Spain, it also helps to understand the effects of gender on the levels of these elements. Similar to studies performed in other geographical regions, no significant gender-related differences could be detected. Although differences were not significant, the levels of zinc, cadmium and lead were modestly higher in males (55.78, 0.346 and 0.424mg/kg, respectively) compared to females (45.25, 0.305 and 0.341mg/kg). Our results indicate that, although gender did not significantly affect heavy metal uptake and toxicokinetics of contaminants in wild boars, these effects could vary between species, populations, organs, and elements. It is therefore essential to investigate gender-related differences for each species.


Asunto(s)
Monitoreo del Ambiente/métodos , Hígado/metabolismo , Metales Pesados/farmacocinética , Caracteres Sexuales , Sus scrofa/metabolismo , Animales , Cadmio/farmacocinética , Cobre/farmacología , Femenino , Hígado/efectos de los fármacos , Masculino , España , Porcinos , Zinc/farmacología
7.
Arch Environ Contam Toxicol ; 71(3): 313-21, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27475645

RESUMEN

The aim of this study was to determine the levels of different inorganic elements (lead [Pb], mercury [Hg], and arsenic [As]) and persistent chlorinated pollutants (including polychlorinated biphenyls [PCBs] and organochlorine pesticides [OCPs]) in blood and plasma of White stork (Ciconia ciconia) nestlings from northwest (NW) Spain. The concentrations of PCBs were lower than the limit of detection in all samples. The OCPs γ-HCH, 4,4'-DDE, HCB, and endosulfan were detected most frequently in plasma from White stork nestlings. These OCPs were detected in 98, 54, 39, and 37 % of all samples, respectively. However, the concentrations of organic pollutants were lower than the risk thresholds for birds. The mean levels of the inorganic elements Pb, Hg, and As were found to be 36.92 ± 33.48, 16.48 ± 12.87, and 9.813 ± 13.84 µg/L, respectively. These levels were also lower than the risk thresholds for birds. This study not only provides a snapshot of the levels of both inorganic and organic contaminants in wild White storks in NW Spain, it also provides a useful baseline for biomonitoring levels of the measured contaminants in this area.


Asunto(s)
Aves/sangre , Monitoreo del Ambiente , Contaminantes Ambientales/metabolismo , Hidrocarburos Clorados/sangre , Metaloides/sangre , Metales/sangre , Animales , España
8.
Knee Surg Sports Traumatol Arthrosc ; 24(6): 1826-35, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27120191

RESUMEN

The diagnosis and the prompt treatment of early osteoarthritis (OA) represent vital steps for delaying the onset and progression of fully blown OA, which is the most common form of arthritis, involving more than 10 % of the world's population older than 60 years of age. Nonsurgical treatments such as physiotherapy, anti-inflammatory medications, and other disease-modifying drugs all have modest and short-lasting effect. In this context, the biological approaches have recently gained more and more attention. Growth factors, blood derivatives, such as platelet concentrates, and mesenchymal adult stem cells, either expanded or freshly isolated, are advocated amongst the most promising tool for the treatment of OA, especially in the early phases. Primarily targeted towards focal cartilage defects, these biological agents have indeed recently showed promising results to relieve pain and reduce inflammation in patients with more advanced OA as well, with the final aim to halt the progression of the disease and the need for joint replacement. However, despite of a number of satisfactory in vitro and pre-clinical studies, the evidences are still limited to support their clinical efficacy in OA setting.


Asunto(s)
Cartílago Articular , Péptidos y Proteínas de Señalización Intercelular/uso terapéutico , Trasplante de Células Madre Mesenquimatosas/métodos , Osteoartritis de la Rodilla/terapia , Plasma Rico en Plaquetas , Regeneración , Tejido Adiposo/citología , Progresión de la Enfermedad , Intervención Médica Temprana , Humanos , Inflamación , Células Madre Mesenquimatosas , Osteoartritis/terapia , Dolor
9.
Rev. chil. obstet. ginecol ; 80(3): 242-245, jun. 2015. ilus
Artículo en Español | LILACS | ID: lil-752874

RESUMEN

ANTECEDENTES: Frecuentemente, las pacientes con endometriosis presentan una elevación de marcadores tumorales Ca 125 y Ca 19.9. No obstante, no existe correlación clara con la expresión clínica ni con el grado de afectación. En algunos casos, es necesario un diagnóstico diferencial con patologías malignas. CASO CLÍNICO: Mujer de 29 años con clínica aislada de dismenorrea moderada y hallazgo de masas ováricas bilaterales con elevación intensa de marcadores tumorales: Ca-125: 7.716 U/mL y Ca-19.9: 995 U/mL. Se decide intervención quirúrgica laparoscópica evidenciándose endometriosis ovárica y extensión peritoneal masiva con afectación de peritoneo parietal abdominal, superficie uterina, fondo de Douglas, parametrios, vejiga, hemidiafragma derecho, hígado y serosa intestinal. Se realiza adhesiolisis cuidadosa, quistectomía y extirpación de múltiples implantes endometriósicos en cavidad abdominal. Se observó un descenso de los marcadores a las 48 horas: Ca-125 de 253 U/mL y Ca 19.9 de 4,9 U/mL, ambos negativos al mes de la cirugía. CONCLUSIÓN: Una elevación intensa de los marcadores tumorales precisa de diagnóstico diferencial en el contexto de la endometriosis. Existe una gran discrepancia entre los valores de los marcadores tumorales con la clínica y severidad de la endometriosis. Los hallazgos quirúrgicos son fundamentales, evidenciando una afectación masiva subdiagnosticada hasta la cirugía.


BACKGROUND: Frequently, patients with endometriosis present elevated tumor marker Ca 125 and Ca 19.9. However, there is no clear correlation with the clinical expression or the degree of involvement. In some cases, differential diagnosis is necessary with malignancies. CASE REPORT: A 29 year old woman with moderate dysmenorrhea and finding of bilateral ovarian masses with intense elevation of tumor markers, CA125: 7,716 U/mL and Ca-19.9: 995 U/mL. Laparoscopic surgery is decided evidenced massive ovarian endometriosis and peritoneal extension with involvement of abdominal peritoneum, uterine surface, Douglas, parametrium, bladder, right hemidiaphragm, liver and intestinal serosa. Careful liberation of adherences, ovarian cystectomy and removal of multiple endometriosic implants. A decrease of tumor markers was observed at 48 hours (Ca-125: 253 U/mL and Ca-19.9: 4.9 U/mL), and negative one month after surgery. CONCLUSION: An intense elevated tumor markers accurate differential diagnosis in the context of endometriosis. There is a large discrepancy between the values of tumor markers with clinical and severity of endometriosis.


Asunto(s)
Humanos , Femenino , Adulto , Antígeno Ca-125/análisis , Endometriosis/diagnóstico , Ovario , Peritoneo , Biomarcadores de Tumor/análisis , Laparoscopía , Antígeno CA-19-9/análisis , Diagnóstico Diferencial , Dismenorrea , Endometriosis/cirugía
10.
Arch Environ Contam Toxicol ; 65(3): 567-74, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23619767

RESUMEN

The effect of orally administered atrazine (25 or 100 mg/kg on days 0, 5, and 10 of the experiment) was studied in European quail (Coturnix coturnix coturnix) on four non-destructive biomarkers: fecal porphyrins, blood glutathione-S-transferase, glutathione reductase, reduced glutathione, and malondialdehyde (MDA). Uroporphyrin I (UPI) and coproporphyrins I and III (CPIII) were the main porphyrins detected in feces. The lowest dose of ATZ caused a significant (P < 0.05) increase in UPI and CPIII at day 5, and the highest dose of ATZ caused an induction of CPI and a significant (P < 0.05) decrease in MDA levels at day 30.


Asunto(s)
Atrazina/toxicidad , Coturnix/metabolismo , Exposición a Riesgos Ambientales , Herbicidas/toxicidad , Peroxidación de Lípido/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Animales , Biomarcadores/metabolismo , Cromatografía Líquida de Alta Presión , Heces/química , Femenino , Fluorometría , Glutatión/sangre , Glutatión Reductasa/sangre , Glutatión Transferasa/sangre , Malondialdehído/sangre , Porfirinas/metabolismo , Espectrofotometría
12.
Philos Trans A Math Phys Eng Sci ; 368(1926): 4103-13, 2010 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-20679125

RESUMEN

The muon ionization cooling experiment (MICE) will demonstrate a new technique for reducing the transverse emittance of a beam of muon particles, which are a species of lepton heavier than the electron species, essential for the realization of a future Neutrino Factory research facility. The first use of the Grid within MICE was to run thousands of Monte Carlo simulations to determine the alignment and statistical errors associated with measurements in MICE, which are made at two points in space on a similar sample of particles. The results of this study quantified the effect of correlations between emittance measurements. As a consequence, it has been determined that an order of magnitude less muons are required to achieve the required statistical accuracy than assuming uncorrelated measurements. This first application of the Grid within the MICE experimental domain has yielded results that could significantly impact upon the necessary running time of the experiment.

13.
Sci Total Environ ; 408(21): 4976-83, 2010 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-20708216

RESUMEN

In this study, the chronic effect of the insecticides carbofuran and deltamethrin on acetylcholinesterase (AChE) activity and malondialdehyde (MDA) and reduced glutathione (GSH) levels were examined in the brain of tench. Both pesticides were evaluated in two separate experiments, and animals were exposed in a continuous flow-system to three different concentrations of carbofuran (0, 10 and 100 microg/L) and deltamethrin (0, 0.0039 and 0.039 microg/L) for 60 days. After that period, animals were kept into pesticide-free water for other 30 days. In all cases, animals were sampled every 10 days all along the experience. AChE activity was significantly inhibited in fish exposed to 100 microg/L of carbofuran, during the first 30 days of exposition, returning to basal levels after this initial period. With respect to deltamethrin exposure, AChE activity was not significantly affected. When considering MDA levels, significant changes could only be detected during the recovery period for both pesticides, with a maximum of induction at 70 and 80 days, respectively associated to the highest dose of carbofuran and deltamethrin. Similarly, GSH levels varied all along the experience, with a maximum of significant increase at day 80 of exposition to the highest dose of both pesticides. This study shows that changes in AChE brain activity in tench can be used as a biomarker of early pesticide exposition in environmental monitoring programs, whereas MDA and GSH levels could be more associated to long-term expositions. The above results confirm and broaden former observations, suggesting that more investigations are needed before these biochemical parameters can be used as biomarkers.


Asunto(s)
Encéfalo/efectos de los fármacos , Carbofurano/toxicidad , Cyprinidae/metabolismo , Insecticidas/toxicidad , Nitrilos/toxicidad , Piretrinas/toxicidad , Acetilcolinesterasa/metabolismo , Animales , Biomarcadores/metabolismo , Encéfalo/metabolismo , Monitoreo del Ambiente , Glutatión/metabolismo , Malondialdehído/metabolismo , Pruebas de Toxicidad Crónica , Contaminantes Químicos del Agua/toxicidad
14.
Acta Paediatr ; 99(9): 1434-6, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20394587

RESUMEN

BACKGROUND: Congenital arteriovenous fistulas are exceptional in childhood and imply a therapeutic challenge. CASE REPORT: A 9-month-old female infant was studied for cephalocorporal disproportion, hypotonia, progressive muscular atrophy and hyperreflexia. Computed tomography of the brain and electroencephalography were normal. Electromyographic patterns suggested proximal myopathic involvement. A continuous murmur with systolic reinforcement was audible in the neck. Angioresonance detected intracranial aneurysmal dilatations behind the bulbo-medullary junction and cerebral panangiography evidenced a direct vertebrovertebral fistula with extra- and intra-cranial varices and extreme medullary compression. Occlusion of the afferent vessel to the aneurismal sack was successfully achieved with a mixture of Histoacryl and 75% lipiodol via a microcatheter. CONCLUSION: Clinical signs of an arteriovenous fistula may be atypical. Considerable cephalocorporal disproportion and a bruit in the cervical or retromastoidal regions must suggest its existence. Complete obliteration with endovascular embolization permits somatic and neurological recovery.


Asunto(s)
Fístula Arteriovenosa , Anomalías Craneofaciales/etiología , Hipotonía Muscular/etiología , Arteria Vertebral , Fístula Arteriovenosa/diagnóstico , Fístula Arteriovenosa/terapia , Embolización Terapéutica , Insuficiencia de Crecimiento/etiología , Femenino , Humanos , Lactante , Angiografía por Resonancia Magnética , Compresión de la Médula Espinal/etiología
15.
Top Companion Anim Med ; 25(1): 64-7, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20188341

RESUMEN

This article describes a case of Chinaberry tree poisoning diagnosed in a dog. The initial clinical signs were variable and included tremors (muscular seizures) and a moderate limp in the dog's back leg, which evolved to a more severe condition in the following hours. Abdominal radiographic evaluation was requested, and abundant small, foreign, radio-dense bodies were detected, which were associated with Chinaberry tree fruits after surgical extraction. Adequate treatment was established, and the patient recovered completely. In addition, we compare clinical and gross postmortem findings in other similar cases reported in the literature. There is a general lack of information of such poisoning in pets.


Asunto(s)
Enfermedades de los Perros/etiología , Melia azedarach/envenenamiento , Intoxicación por Plantas/veterinaria , Animales , Enfermedades de los Perros/diagnóstico , Enfermedades de los Perros/terapia , Perros , Femenino , Dolor/etiología , Dolor/veterinaria , Intoxicación por Plantas/diagnóstico , Intoxicación por Plantas/etiología , Intoxicación por Plantas/terapia , Resultado del Tratamiento
16.
Phys Rev E Stat Nonlin Soft Matter Phys ; 79(4 Pt 2): 046604, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19518368

RESUMEN

A technique for the accurate computation of the electromagnetic fields radiated by a charged particle moving within a parallel-plate waveguide is presented. Based on a transformation of the time-varying current density of the particle into a time-harmonic current density, this technique allows the evaluation of the radiated electromagnetic fields both in the frequency and time domains, as well as in the near- and far-field regions. For this purpose, several accelerated versions of the parallel-plate Green's function in the frequency domain have been considered. The theory has been successfully applied to the multipactor discharge occurring within a two metal-plates region. The proposed formulation has been tested with a particle-in-cell code based on the finite-difference time-domain method, obtaining good agreement.

17.
Sci Total Environ ; 407(14): 4320-6, 2009 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-19403160

RESUMEN

The uptake and transfer of natural radionuclides, other than (40)K, from soil to mushrooms has been somewhat overlooked in the literature. Their contribution to the dose due to the consumption of mushrooms was considered negligible. But the contribution of (210)Pb in areas unaffected by any recent radioactive fallout has been found to be significant, up to 35% of the annual dose commitment in Spain. More than 30 species of mushrooms were analyzed, and the (210)Pb detected was in the range of 0.75-202 Bq/kg d.w. A slight difference was observed between species with different nutritional mechanisms (saprophytes > or = mycorrhizae). The (210)Pb content was correlated with the stable lead content, but not with its predecessor in the uranium radioactive series, (226)Ra. This suggested that (210)Pb was taken up from the soil by the same pathway as stable lead. The bioavailability of (210)Pb in soil was determined by means of a sequential extraction procedure (NH(4)OAc, 1M HCl, 6M HCl, and residue). About 30% of the (210)Pb present in the soil was available for transfer to mushrooms, more than other natural radionuclides in the same ecosystem. Lycoperdon perlatum, Hebeloma cylindrosporum, and Amanita curtipes presented the highest values of the available transfer factor, ATF. As reflected in their ATF values, the transfer from soil to mushroom of some natural and anthropogenic radionuclides was in the following order:


Asunto(s)
Hongos/química , Radioisótopos de Plomo/análisis , Contaminantes Radiactivos del Suelo/análisis , España
18.
Environ Toxicol ; 24(2): 187-99, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18561303

RESUMEN

We investigated if residues of simazine in the natural waters would cause histological, hematological, and biochemical alterations in carps from contaminated areas in Badajoz (Spain). Some necrotic foci in kidney and liver, hepatitis, and hepatic steatosis were detected. No changes on measured hematological and biochemical parameters between fish from reference and contaminated ponds were observed. To assess if simazine exposure was the cause of these observations carps were exposed in the laboratory to simazine (45 microg/L) for 90 days. Some results obtained in the field were confirmed in laboratory, such as necrosis in kidney and liver and hepatic steatosis. Globular eosinophilic foci in kidney and a slight decrease of the hematocrit were also detected. These changes were moderate and indicative of an adaptation of the fish to the toxic stress caused by exposure to low simazine concentrations.


Asunto(s)
Carpas , Simazina/análisis , Simazina/farmacología , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/farmacología , Animales , Hematócrito , Hemoglobinas/análisis , Riñón/efectos de los fármacos , Riñón/patología , L-Lactato Deshidrogenasa/sangre , Simazina/análogos & derivados , España , Factores de Tiempo
19.
Environ Toxicol ; 23(3): 285-93, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18214903

RESUMEN

Several water-contamination incidents with simazine have occurred in the province of Badajoz (Spain), due to its excessive use for controlling weeds in olive trees and vineyards. Simazine residues were also detected in drinking water, increasing public health concern. However, little is known on the effects that low levels of simazine pose to environment organisms. We investigated if residues of simazine in the natural waters would affect brain and muscle acetylcholinesterase activity in common carps captured in areas in which simazine residues were detected at average levels of 4.5 microg/L. Results confirmed depression on brain and muscle acetylcholinesterase activity of 20% and 29%, respectively, in carps inhabiting one of the simazine-contaminated ponds, termed "Molinos de Matachel." To assess the biological significance of this finding, we developed a controlled laboratory study in which carps were exposed to simazine at 45 microg/L (10-fold that of the natural water levels) for 90 days. The results obtained in the field study were not confirmed in our laboratory experiment, since carps did not show evidence or brain or muscle acetylcholinesterase activity depression for the duration of the experiment, and therefore, we can conclude that acetylcholinesterase depression found in carps collected in "Molinos de Matachel" should be ascribed to other compounds or mixtures of xenobiotics.


Asunto(s)
Acetilcolinesterasa/metabolismo , Encéfalo/efectos de los fármacos , Carpas/metabolismo , Herbicidas/toxicidad , Músculos/efectos de los fármacos , Simazina/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Encéfalo/enzimología , Femenino , Masculino , Músculos/enzimología
20.
Tissue Cell ; 39(2): 99-108, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17379266

RESUMEN

Sperm nucleomorphogenesis in the cephalopod Sepia officinalis is the product of the interaction between perinuclear microtubules and condensing chromatin. This interaction occurs during spermiogenesis and is established through the nuclear membrane. As in other cephalopod species, the perinuclear microtubules are transient structures. In the case of S. officinalis, they begin to appear in the basal area of the early spermatid and progress from there, establishing contact with the external nuclear membrane and follow a defined, but not symmetric, geometry. Thus, the microtubules accumulate preferentially in one area of the nuclear membrane which we refer to here as the "dorsal zone". Later, the microtubules will be eliminated before the mature spermatid migrates to the epidydimis. The chromatin is condensed within the nucleus following a complex pattern, beginning as fibro-granular structures until forming fibres of approximately 45 nm diameter (patterning phases). From this stage on, an increase in the chemical basicity of DNA-interacting proteins is produced, and chromatin fibres coalesce together, being recruited to the dorsal zone of the membrane, where there is a higher density of microtubules. This last step (condensation phases) allows the chromatin fibres to be arranged parallel to the axis of the elongating nucleus, and more importantly, is deduced to cause a lateral compression of the nucleus. This lateral compression is in fact a recruitment of the ventral zone toward the dorsal zone, which brings about an important reduction in nuclear volume. The detailed observations which comprise this work complement previous studies of spermiogenesis of Sepia and other cephalopods, and will help to better understand the process of cellular morphology implicated in the evolution of sperm nuclear shape in this taxonomic group.


Asunto(s)
Núcleo Celular/metabolismo , Sepia/citología , Espermatogénesis , Espermatozoides/citología , Animales , Núcleo Celular/ultraestructura , Cromatina/metabolismo , Cromatina/ultraestructura , Masculino , Microtúbulos/metabolismo , Microtúbulos/ultraestructura , Membrana Nuclear/metabolismo , Membrana Nuclear/ultraestructura , Sepia/ultraestructura , Espermatozoides/ultraestructura
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