RESUMO
Cerebral aneurysm affects 2-5% of the population and posterior inferior cerebellar artery (PICA) aneurysms account for 1-3% of all intracranial aneurysms. Oxidative stress is known to contribute to the progression of cerebrovascular disease and it may be increased by inflammation, a key contributor to cerebral aneurysm development and rupture. The aim of this study was to examine the role of overall oxidative stress as a risk factor for rupture of PICA aneurysms. This study included 29 patients with PICA aneurysms: 18 ruptured and 11 unruptured. We determined catalase, malondialdehyde, myeloperoxidase and carbonyl groups in homogenates of excised aneurysm tissue after surgery and plasma levels of C reactive protein and fibrinogen. The patient's age and sex, size of aneurysms, multiplicity, history of previous subarachnoidal hemorrhage (SAH) and risk factors for oxidative stress such as hypertension and smoking were compared between unruptured and ruptured aneurysms. Maximal diameter and SAH history were independent predictors for aneurysm rupture. Activity of catalase was decreased while activity of myeloperoxidase, levels of malondialdehyde, carbonyl groups in aneurismal tissue and plasma levels of C reactive protein and fibrinogen were increased in patients with ruptured aneurysms. Plasma levels of C reactive protein and fibrinogen showed positive correlation with myeloperoxidase, malondialdehyde, carbonyl groups and PHASES score and negative correlation with catalase. These findings suggest that oxidative stress may contribute importantly to rupture of PICA aneurysms and plasma levels of C reactive protein and fibrinogen correlate with oxidative stress markers in tissue.
Assuntos
Aneurisma Roto/metabolismo , Aneurisma Intracraniano/metabolismo , Estresse Oxidativo/fisiologia , Idoso , Artérias , Biomarcadores/sangue , Proteína C-Reativa/análise , Catalase/análise , Cerebelo , Feminino , Fibrinogênio/análise , Humanos , Masculino , Malondialdeído/análise , Pessoa de Meia-Idade , Peroxidase/análise , Fatores de Risco , Sérvia , Hemorragia Subaracnóidea , Tomografia Computadorizada por Raios XRESUMO
Traces of particulate radioactive iodine (131I) were detected in the European atmosphere in January/February 2017. Concentrations of this nuclear fission product were very low, ranging 0.1 to 10 µBq m-3 except at one location in western Russia where they reached up to several mBq m-3. Detections have been reported continuously over an 8-week period by about 30 monitoring stations. We examine possible emission source apportionments and rank them considering their expected contribution in terms of orders of magnitude from typical routine releases: radiopharmaceutical production units > sewage sludge incinerators > nuclear power plants > spontaneous fission of uranium in soil. Inverse modeling simulations indicate that the widespread detections of 131I resulted from the combination of multiple source releases. Among them, those from radiopharmaceutical production units remain the most likely. One of them is located in Western Russia and its estimated source term complies with authorized limits. Other existing sources related to 131I use (medical purposes or sewage sludge incineration) can explain detections on a rather local scale. As an enhancing factor, the prevailing wintertime meteorological situations marked by strong temperature inversions led to poor dispersion conditions that resulted in higher concentrations exceeding usual detection limits in use within the informal Ring of Five (Ro5) monitoring network.
Assuntos
Poluentes Radioativos do Ar , Neoplasias da Glândula Tireoide , Europa (Continente) , Humanos , Radioisótopos do Iodo , Federação RussaRESUMO
AIM: Constitutive release of NO blunts intrinsic and stimulated contractile activity in cerebral arteries (CA). Here, we explored whether phosphorylation and expression levels of the PKG-sensitive, leucine zipper positive (LZ+ ) splice variants of the regulatory subunit of myosin phosphatase (MYPT1) are involved and whether its expression is associated with higher cGMP sensitivity. METHODS: Vascular contractility was investigated by wire myography. Phosphorylation of MYPT1 was determined by Western blotting. RESULTS: Constitutive phosphorylation of MYPT1-T696 and T853 was lower and that of S695 and S668 was higher in cerebral arteries from the circulus arteriosus (CA-w) than in femoral arteries (FA), while total MYPT1 expression was not different. In CA-w but not in FA, L-NAME lowered phosphorylation of S695/S668 and increased phosphorylation of T696/T853 and of MLC20 -S19, plus basal tone. The increase in basal tone was attenuated in CA-w and basilar arteries (BA) from heterozygous MYPT1-T696A/+ mice. Compared to FA, expression of the LZ+ -isoform was ~2-fold higher in CA-w coincident with a higher sensitivity to DEA-NONOate, cinaciguat and Y27632 in BA and 8-Br-cGMP (1 µmol/L) in pre-constricted (pCa 6.1) α-toxin permeabilized CAs. In contrast, 6-Bnz-cAMP (10 µmol/L) relaxed BA and FA similarly by ~80%. CONCLUSION: Our results indicate that (i) regulation of the intrinsic contractile activity in CA involves phosphorylation of MYPT1 at T696 and S695/S668, (ii) the higher NO/cGMP/PKG sensitivity of CAs can be ascribed to the higher expression level of the LZ+ -MYPT1 isoform and (iii) relaxation by cAMP/PKA pathway is less dependent on the expression level of the LZ+ splice variants of MYPT1.
Assuntos
Círculo Arterial do Cérebro/enzimologia , GMP Cíclico/metabolismo , Artéria Femoral/enzimologia , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Óxido Nítrico/metabolismo , Vasoconstrição , Vasodilatação , Processamento Alternativo , Animais , Círculo Arterial do Cérebro/efeitos dos fármacos , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Artéria Femoral/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfatase de Miosina-de-Cadeia-Leve/deficiência , Fosfatase de Miosina-de-Cadeia-Leve/genética , Fosforilação , Sistemas do Segundo Mensageiro , Vasoconstrição/efeitos dos fármacos , Vasoconstritores/farmacologia , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
The aim of this study was to assess the effects of L-cysteine (Cys) (7 mg/kg) and N-acetyl-L-cysteine (NAC) (50 mg/kg) in the rat liver caused by subchronic i.p. application of methionine (Met) (0.8 mmol/kg) during 21 days. Malondialdehyde (MDA) concentration, glutathione content (GSH), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and acetylcholinesterase (AchE) activities were determined in the liver tissue and activities of liver enzymes (AST, ALT, ALP, and GGT) and concentrations of total proteins and albumin were determinated in plasma/serum. Catalase, superoxide dismutase, and acetylcholinesterase activities were increased by Cys and NAC. Met caused periportal mononuclear infiltration and rare focal necrosis of hepatocytes. In Cys- and NAC-supplemented groups, intracellular edema and microvesicular fatty changes without necrosis were noticed. We observed decrease of AST, ALT, and ALP activity in the methionine-treated group. Our results indicate that Cys and NAC application can increase activity of antioxidative enzymes and prevent intensive histological changes in liver in condition of subchronic methionine exposure.
Assuntos
Fígado/metabolismo , Metionina/efeitos adversos , Estresse Oxidativo/efeitos dos fármacos , Acetilcisteína/farmacologia , Animais , Glutationa/metabolismo , Hepatócitos/metabolismo , Hepatócitos/patologia , Fígado/patologia , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Malondialdeído/metabolismo , Metionina/farmacologia , Necrose , Oxirredutases/metabolismo , Ratos , Ratos WistarRESUMO
In this paper the impact of the Solar magnetic field on 7Be activity concentration in aerosols was investigated. The changes in the 7Be activity in aerosols in the period from the second part of 22nd to the second part of 24th Solar cycle were mathematically processed using the Fourier analysis and the 22 years period was pointed out. It corresponds to the most intense period of the Solar polar field strength for the same observed period. The Pearson's linear coefficient between the average annual value of 7Be activity in aerosols and the Solar polar field strength was 0.58.
RESUMO
Air sample monitoring in Serbia, Belgrade started in the 1960s, while (7)Be activity in air and total (dry and wet) deposition has been monitored for the last 22 years by the Environment and Radiation Protection Department of the Institute for Nuclear Sciences, Vinca. Using this data collection, the changes of the (7)Be activity in the air and the total (wet and dry) deposition samples, as well as their correlation with meteorological parameters (temperature, pressure, cloudiness, sunshine duration, precipitation and humidity) that affect (7)Be concentration in the atmosphere, were mathematically described using the Fourier analysis. Fourier analysis confirmed the expected; the frequency with the largest intensity in the harmonic spectra of the (7)Be activity corresponds to a period of 1 year, the same as the largest intensity frequency in Fourier series of meteorological parameters. To analyze the quality of the results produced by the Fourier analysis, we compared the measured values of the parameters with the values calculated according to the Fourier series. Absolute deviations between measured and predicted mean monthly values are in range from 0.02 mBq/m(3) to 0.7 mBq/m(3) for (7)Be activity in air, and 0.01 Bq/m(2) and 0.6 Bq/m(2) for (7)Be activity in deposition samples. Relatively good agreement of measured and predicted results offers the possibility of prediction of the (7)Be activity.
Assuntos
Poluentes Radioativos do Ar/análise , Atmosfera/química , Berílio/análise , Análise de Fourier , Meteorologia , Monitoramento de Radiação/métodos , Umidade , SérviaRESUMO
Methods for photoacoustic signal measurement, rectification, and analysis for 85 µm thin Si samples in the 20-20 000 Hz modulation frequency range are presented. Methods for frequency-dependent amplitude and phase signal rectification in the presence of coherent and incoherent noise as well as distortion due to microphone characteristics are presented. Signal correction is accomplished using inverse system response functions deduced by comparing real to ideal signals for a sample with well-known bulk parameters and dimensions. The system response is a piece-wise construction, each component being due to a particular effect of the measurement system. Heat transfer and elastic effects are modeled using standard Rosencweig-Gersho and elastic-bending theories. Thermal diffusion, thermoelastic, and plasmaelastic signal components are calculated and compared to measurements. The differences between theory and experiment are used to detect and correct signal distortion and to determine detector and sound-card characteristics. Corrected signal analysis is found to faithfully reflect known sample parameters.
RESUMO
The charcoal canister method of radon measurement according to US Environment Protection Agency protocol 520/5-87-005 is widely used for screening. This method is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. For the purpose of gamma spectrometry, appropriate efficiency calibration of the measuring system must be performed. The most usual method of calibration is using standard canister, a sealed canister with the same matrix and geometry as the canisters used for measurements, but with the known activity of radon. In the absence of standard canister, a different method of efficiency calibration has to be implemented. This study presents the results of efficiency calibration using the EFFTRAN efficiency transfer software. Efficiency was calculated using a soil matrix cylindrical secondary reference material as a starting point. Calculated efficiency is then compared with the one obtained using standard canister and applied to a realistic measurement in order to evaluate the results of the efficiency transfer.
Assuntos
Contaminação Radioativa do Ar/análise , Carvão Vegetal/química , Germânio/química , Monitoramento de Radiação/instrumentação , Monitoramento de Radiação/métodos , Radônio/análise , CalibragemRESUMO
The determination of radionuclide activity concentration requires a prior knowledge of the full-energy peak (FEP) efficiency at all photon energies for a given measuring geometry. This problem has been partially solved by using procedures based on Monte Carlo simulations, developed in order to complement the experimental calibration procedures used in gamma-ray measurements of environmental samples. The aim of this article is to apply GEANT4 simulation for calibration of two HPGe detectors, for measurement of liquid and soil-like samples in cylindrical geometry. The efficiencies obtained using a simulation were compared with experimental results, and applied to a realistic measurement. Measurement uncertainties for both simulation and experimental values were estimated in order to see whether the results of the realistic measurement fall within acceptable limits. The trueness of the result was checked using the known activity of the measured samples provided by IAEA.
Assuntos
Calibragem/normas , Modelos Estatísticos , Monitoramento de Radiação/instrumentação , Monitoramento de Radiação/normas , Manejo de Espécimes/normas , Espectrometria gama/instrumentação , Espectrometria gama/normas , Algoritmos , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Raios gama , Internacionalidade , Método de Monte Carlo , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Sérvia , SoftwareRESUMO
Active charcoal detectors are used for testing the concentration of radon in dwellings. The method of measurement is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. The contributions to the final measurement uncertainty are identiï¬ed, based on the equation for radon activity concentration calculation. Different methods for setting the region of interest for gamma spectrometry of canisters were discussed and evaluated. The obtained radon activity concentration and uncertainties do not depend on peak area determination method.
RESUMO
Conventional radiotherapy with X- and gamma-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and (12)C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with gamma-rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u (12)C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than gamma-rays. The best efficiency was obtained with (12)C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for (12)C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and (12)C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance.
Assuntos
Apoptose/efeitos da radiação , Carbono , Proliferação de Células/efeitos da radiação , Raios gama , Melanoma/patologia , Prótons , Fatores de Tempo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos da radiação , Relação Dose-Resposta à Radiação , Humanos , Íons , Transferência Linear de Energia , Tolerância a RadiaçãoRESUMO
The effects of irradiation with gamma rays and protons on HTB140 human melanoma cell morphology and viability were analyzed. Exponentially growing cells were irradiated close to the Bragg peak maximum of the 62-MeV proton beam, as well as with (60)Co gamma rays, with doses ranging from 8 to 24 Gy. The overall cell morphology was unchanged 6 and 48 h after gamma irradiation, also showing a relatively weak cell-inactivation level. After exposure to proton beam, considerable changes in cell morphology followed by stronger cell inactivation were achieved. Proliferation capacity of irradiated cells significantly decreased in both experimental set-ups. Higher ionization level of protons with respect to gamma rays, representing the main physical difference between these two types of radiation, was also revealed on the cell membrane level through larger pro-apoptotic capacity of protons.
Assuntos
Linhagem Celular Tumoral/citologia , Linhagem Celular Tumoral/efeitos da radiação , Sobrevivência Celular , Raios gama , Melanoma , Prótons , Proliferação de Células/efeitos da radiação , Forma Celular/efeitos da radiação , HumanosRESUMO
7Be to 210Pb concentration ratios in ground level air on two monitoring stations (MS1 and MS2) in Belgrade area were determined from 1996 to 2001. The average monthly concentrations of 7Be in ground level air were in the range of 0.6-18.3 mBq/m3 and exhibited one or two summer/early fall maxims and one minimum in winter. The maximum concentrations for 210Pb were generally observed in the fall, with the average concentrations in the range of 1.09 x 10(-4) to 30.9 x 10(-4) Bq/m3. The 7Be/210Pb ratios were in the range of 1.7-12.7 (MS1) and 1.8-11.3 (MS2), with summer maxims and late fall/winter minimums. The mean Radionuclides Loading Indices values approach zero except for 1996/1997 (MS1) and 2001 (MS2) due to higher concentrations of 7Be and 210Pb. The mean monthly concentrations of both radionuclides exhibited lognormal distributions. There is significant correlation between the 7Be/210Pb activities ratio and the air stability classes A + B + C for both monitoring stations (correlation coefficients 0.61-0.65), and no correlation with D class and E + F classes. Correlation was found between the activity of 7Be and air stability classes A + B + C (0.46-0.68), and E + F (0.38 for MS1), while for 210Pb, a moderate correlation (0.38-0.40) was found with the E + F air stability classes.
Assuntos
Poluentes Radioativos do Ar/análise , Berílio/análise , Radioisótopos de Chumbo/análise , Radioisótopos/análise , Monitoramento Ambiental , IugosláviaRESUMO
A general framework for the explanation of perceptual phenomena as internalizations of external regularities was developed by R. N. Shepard. A particular example of this framework is his account of perceived curvilinear apparent motions. This paper contains a brief summary of the relevant psychophysical data, some basic kinematical considerations and examples, and several criticisms of Shepard's account. The criticisms concern the feasibility of internalization of critical motion types, the roles of simplicity and uniqueness, the contrast between classical physics and kinematic geometry, the import of perceived path curvilinearity, and the relation of perceptual and scientific knowledge.
Assuntos
Fenômenos Biomecânicos , Percepção de Movimento , Humanos , Fenômenos Físicos , FísicaRESUMO
The lightness of a test patch completely surrounded by an inducing field can be predicted by variants of Wallach's ratio rule. When a patch is surrounded by two or more regions with different luminances, a plausible extension of the ratio rule would predict that the effect of the surrounding regions should correlate with the length of the border they share with the test patch. However, as shown by the Wertheimer-Benary and White effects, lightness of such patches can depart appreciably from these predictions. It is argued that a fruitful approach toward the explanation of such effects is based on the analysis of junctions (such as T-junctions and X-junctions) between regions. Several new displays and variations of old displays involving such junctions are used to illustrate this approach. An alternative analysis of a lightness effect introduced by Adelson is provided, and the role of depth effects in achromatic perception is discussed. A number of limitations of the approach and possible ways to overcome them are noted.
Assuntos
Sensibilidades de Contraste/fisiologia , Iluminação , Ilusões Ópticas , Percepção de Profundidade/fisiologia , HumanosRESUMO
Phonologically ambiguous Serbo-Croatian words are identified more slowly and erroneously than their phonologically unique counterparts. Five experiments addressed the reduction of these ambiguity effects when Roman (Cyrillic) targets are preceded by consonants unique to the Roman (Cyrillic) alphabet. Alphabet-specific nonword contexts were presented briefly with masking. With forward masking, performance was better when the phonologically ambiguous target words and their preceding nonword contexts were alphabetically congruent. Similarly, where backward masked contexts acted themselves as backward masks for the target stimuli, identification was highest when the context masks were in the same alphabet as the targets. Results were discussed in terms of automatic, prelexical processes within a network model of visual word recognition in Serbo-Croatian.
Assuntos
Atenção , Idioma , Fonética , Leitura , Adolescente , Humanos , Rememoração Mental , Aprendizagem Verbal , IugosláviaRESUMO
The authors studied Duchenne muscular dystrophy (DMD) in 14 Yugoslav families with 16 diseased men. All the sixteen patients showed typical phenotypic features of DMD. The linkage analysis was done with five probes 754, C7, PERT87.15, pERT87.30, and pERTBir. A deletion with pERT87.15 (DX 164) in one family was found. Deletion analysis was mainly performed using cDNA probes and multiplex PCR analysis. Preferential deletions were in the hot spot deletion region covered by cDNA probe 8. Among 14 examined patients with cDNA hybridization deletions were found in 5 cases (5/14). For quick and prenatal analysis the authors used multiplex PCR. With this methods deletions were found in 4 cases (4/15). The percentage of the observed deletions cases was 50% (8/16) in Yugoslav population, which shows good correlation with other European and American populations studied. Prenatal diagnosis was done for two consultants with highly ambiguous carrier risk, and no deletions were found.
Assuntos
Deleção Cromossômica , Distrofias Musculares/genética , Criança , Sondas de DNA , Triagem de Portadores Genéticos , Humanos , Masculino , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de RestriçãoRESUMO
Recent results towards development of a neural network architecture for general-purpose preattentive vision are summarized. The architecture contains two parallel subsystems, the boundary contour system (BCS) and the feature contour system (FCS), which interact together to generate a representation of form-and-color-and-depth. Emergent boundary segmentation within the BCS and featural filling-in within the FCS are herein emphasized within a monocular setting. Applications to the analysis of boundaries, textures, and smooth surfaces are described, as is a model for invariant brightness perception under variable illumination conditions. The theory shows how suitably defined parallel and hierarchical interactions overcome computational uncertainties that necessarily exist at early processing stages. Some of the psychophysical and neurophysiological data supporting the theory's predictions are mentioned.
Assuntos
Simulação por Computador , Modelos Neurológicos , Percepção Visual/fisiologia , Inteligência Artificial , HumanosRESUMO
Morphosyntactic capacities of normal brain hemispheres were compared in lexical decision studies involving centrally and laterally presented Serbo-Croatian nouns in different cases. Cases are distinguished by different suffixes and syntactic roles. Experiment 1 confirmed and extended previous findings of the nominative superiority effect: words in the nominative case were processed faster and more accurately than words in other three cases, and nonwords in the nominative case led to more false positive reactions than nonwords in other cases. In Experiment 2 this effect was replicated for right visual field stimuli: nominatives had faster reaction times and smaller error rates than accusatives, and the reversed pattern was found for nonwords. For left visual field stimuli, only the word error analysis found the nominative superior, while the other three analyses (word reaction times, nonword reaction times, and nonword error rates) showed no significant case effect. Word familiarity had an equally strong effect in both hemispheres. The results suggest that centrally presented stimuli are processed by the left hemisphere, that laterally presented stimuli are processed by the initially receiving hemisphere, and that the right hemisphere has a frequency-sensitive lexicon. Reduced right-hemisphere sensitivity for case differences may be due to different lexicon structure or the absence of appropriate morphological or syntactic mechanisms.