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An actinide N4,5 branching ratio analysis of PuO2 and UO2 has been performed, including measurements with a scanning transmission electron microscope at the Advanced Light Source. It is shown that the 5f occupation of the Pu in plutonium dioxide is n = 5. This is contrary to recent results from another technique.
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Objective: To evaluate the right ventricular function using two-dimensional speckle tracking echocardiography (2-D STE) and analyze the associated risk factors of right ventricular dysfunction in patients with silicosis. Methods: All 104 patients with silicosis treated in the Department of Occupational Medicine and Toxicology in Beijing Chao-Yang Hospital, Capital Medical University from May 2021 to September 2022 were enrolled in this study in October 2022. The clinical information of patients such as general data, arterial blood gas analysis and pulmonary function test were collected. The right ventricular function of patients was evaluated by 2-D STE-derived right ventricular free wall longitudinal strain (RVFWLS) and conventional echocardiographic-derived parameters, including right ventricular fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE) and doppler tissue imaging-derived tricuspid lateral annular systolic velocity (S'), respectively. Based on their RVFWLS, the patients were divided into right ventricular dysfunction group and normal right ventricular function group. Risk factors for right ventricular dysfunction in patients with silicosis were analyzed using binary logistic regression analysis. Results: A total of 104 silicosis patients were enrolled, with aneverage age (65.52±11.18) years old, among whom including 57 cases diagnosed with stage â /â ¡ silicosis and 47 cases diagnosed with stage â ¢ silicosis. 26 (25.00%) patients concurrent right ventricular dysfunction. The abnormal rates of RVFAC, TAPSE and S' in patients were 16.35% (17 cases), 21.15% (22 cases) and 6.73% (7 cases), respectively. The RVFAC and TAPSE in right ventricular dysfunction group were lower than those in normal right ventricular function group, and the incidence of pulmonary arterial systolic pressure ≥36 mmHg was higher than that in normal right ventricular function group (P<0.05). Logistic regression analysis showed that arterial partial pressure of oxygen (OR=0.932, 95%CI: 0.885-0.981, P=0.007) was the protective factor, and the forced expiratory volume in 1 second (FEV(1)) /forced vital capacity (FVC) ratio<70% (OR=5.484, 95%CI: 1.049-28.662, P=0.044) and stage â ¢ silicosis (OR=6.343, 95%CI: 1.698-23.697, P=0.007) were the risk factors for silicosis patients concurrent right ventricular dysfunction. Conclusion: The incidence of right ventricular dysfunction is higher in patients with stage â ¢ silicosis than that in patients with stage â /â ¡ silicosis. Using 2-D STE can help the early detection of silicosis with right ventricular dysfunction. Hypoxemia, airflow limitation and the stage â ¢ silicosis are the risk factors for silicosis patients concurrent right ventricular dysfunction.
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Silicose , Disfunção Ventricular Direita , Humanos , Pessoa de Meia-Idade , Idoso , Disfunção Ventricular Direita/diagnóstico por imagem , Disfunção Ventricular Direita/etiologia , Função Ventricular Direita , Ecocardiografia , Fatores de Risco , Silicose/complicações , Silicose/diagnóstico por imagemRESUMO
Objective: To investigate the clinical characteristics of patients with acute phosphine poisoning, and to follow up and evaluate the prognosis of patients. Methods: In May 2022, 12 patients with phosphine poisoning by respiratory inhalation in Beijing Chao-Yang Hospital of Capital Medical University were analyzed. The patients were treated with symptomatic support therapy. Three months later, patients were re-evaluated the symptoms of poisoning, pulmonary function and magnetic resonance imaging (MRI) of the brain to understand the prognosis of the phosphine poisoning. Results: The main symptoms of 12 patients were respiratory and central nervous system symptoms with hypoxia. The symptoms of poisoning improved after treatment. Follow-up found that the patients had different degrees of residual symptoms. Pulmonary function showed increased airway resistance. Airway challenge test was positive in some patients. MRI of the head of some patients showed small ischemic focus in bilateral frontal lobes. Conclusion: Acute phosphine poisoning may cause persistent damage to the respiratory system and central system, and residual symptoms after 3 months.
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Doenças do Sistema Nervoso Central , Fosfinas , Intoxicação , Doenças Respiratórias , Humanos , Seguimentos , Pulmão , Fosfinas/intoxicação , Intoxicação/diagnóstico , Doenças do Sistema Nervoso Central/induzido quimicamente , Doenças Respiratórias/induzido quimicamenteRESUMO
Objective: To investigate the characteristics of and associated risk factors for pulmonary dysfunction in silicosis patients with progressive massive fibrosis (PMF) . Methods: In-patients with PMF treated in the Department of Occupational Medicine and Toxicology in Beijing Chao-Yang Hospital, Capital Medical University from June 2014 to October 2020 were enrolled in this study. Based on their pulmonary ventilation function, the patients were divided into normal ventilation group, obstructive ventilation dysfunction group, restrictive ventilation dysfunction group, and mixed ventilation dysfunction group. The location and area of the large opacity and the grade of emphysema were evaluated by high-resolution CT (HRCT) of the chest. Based on the location, the large opacity was classified into central type, peripheral type, and mixed type. Results: A total of 115 silicosis patients with PMF were enrolled, with 85 (73.91%) having different types of pulmonary dysfunction, including 36 cases (31.30%) in the obstructive ventilation dysfunction group, 9 cases (7.83%) in the restrictive ventilation dysfunction group and 40 cases (34.78%) in the mixed ventilation dysfunction group. As for the location of the large opacity, 41 cases (35.65%) were central type, 52 cases (45.22%) were peripheral type, and 22 cases (19.13%) were mixed type. Logistic regression analysis showed that the central large opacity and grade 3-4 emphysema were risk factors for obstructive ventilation dysfunction (OR=52.179, 5.500, P<0.05) , class C large opacity was the risk factor for restrictive ventilation dysfunction (OR=33.146, P<0.05) , class B, class C large opacity and central large opacity were the risk factors for mixed ventilation dysfunction (OR=6.414, 11.561, 19.600, P<0.05) . Conclusion: In silicosis patients with PMF, the incidence rate of pulmonary ventilation dysfunction is higher, mainly obstructive and mixed ventilation dysfunction. The area and location of large opacity are associated with the incidence and types of pulmonary ventilation dysfunction.
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Pneumoconiose , Enfisema Pulmonar , Silicose , Fibrose , Humanos , Pulmão/patologia , Pneumoconiose/patologia , Silicose/complicações , Silicose/epidemiologia , Silicose/patologiaRESUMO
Economic development and the evolution of food industry not only help to meet the human needs for food, but also cause worldwide health problems. Due to the imbalance of economic development and the difference of dietary habits, the population in China is faced with the problem of excessive food intake, obesity and the possible deficiency of some nutrients. In the past few decades, the food industry has profoundly affected people's intake patterns of nutrients such as energy, fat, salt and added sugar, as well as changed the nutritional structure of food and the risk of exposure to harmful substances. Food contamination caused by pathogenic microorganisms, pesticides and heavy metals are serious concerns. The dietary guidelines for Chinese residents provide basic principles for guiding the dietary behaviors of the public, but their implementation is hampered by people's lack of understanding of food and nutrition, traditional dietary habits, media misinformation and other factors. How to provide healthy and safe food for the people is an important issue at present. This paper discusses some basic concepts of healthy diet, how to promote healthy eating habits through education, how to preserve and process food to maintain nutrition, how to control food safety hazards, and other dietary related approaches that can promote health.
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Dieta/psicologia , Inocuidade dos Alimentos , Política Nutricional , Estado Nutricional , China , HumanosRESUMO
Objective: To evaluate the efficacy and safety of pirfenidone (PFD) in idiopathic pulmonary fibrosis (IPF) in real-life world. Methods: 47 consecutive patients with IPF taking PFD for at least 12 months (PFD group) were included for analysis, with 47 patients with IPF who did not take PFD as controls. Data were collected from clinical charts to evaluate the lung function parameters and the adverse reactions of PFD. Results: In the PFD group, the percent predicted forced vital capacity (FVC%) and diffusing capacity of carbon monoxide (D(L)CO%) increased by (3.5±7.2)% and (1.1±6.1)% after 6 months of PFD treatment compared with the baseline, while the mean decline of FVC% and D(L)CO% was(2.3±6.7)% and (4.7±6.2)% in the controls (t=2.166, P=0.041; t=2.519, P=0.018). After 12 months of treatment, FVC% increased by (2.3±7.0)% and D(L)CO% decreased by(1.3±12.2)% compared with the baseline, while the mean decline of FVC% and D(L)CO% was (3.3±6.2)% and (5.3±9.8)% in the controls (t=2.292, P=0.030; t=1.047, P=0.303). In the PFD group, 17 patients regularly received pulmonary function test per 6 months. The mean decline in FVC% and D(L)CO% was(6.0±8.2)% and(7.0±13.3)% from 6 month before treatment to baseline when PFD was started, while the FVC% increased by (3.9±7.8)% and D(L)CO% increased by(1.3±6.6)% after 6 months of treatment compared with the baseline (Z=-2.897, P=0.004; Z=-2.151, P=0.031). The proportion of patients with more than 5% or 10% decline in FVC% decreased significantly after 6 months therapy (P=0.010 and 0.018, respectively). Adverse events were commonly seen in 30 patients while taking pirfenidone. The most common adverse events were gastrointestinal symptoms and skin reactions. Conclusions: In real-life world, PFD therapy for 12 months showed good effectiveness on pulmonary functions in patients with mild to severe IPF. Adverse events were common but mild.
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Anti-Inflamatórios não Esteroides/administração & dosagem , Fibrose Pulmonar Idiopática/tratamento farmacológico , Piridonas/administração & dosagem , Anti-Inflamatórios não Esteroides/efeitos adversos , Humanos , Piridonas/efeitos adversos , Resultado do Tratamento , Capacidade VitalRESUMO
BACKGROUND: The purpose of the present study was to determine whether intrahepatic injection of (131)I-lipiodol (Lipiodol) is effective against recurrence of surgically resected hepatocellular carcinoma (HCC). METHODS: From June 2001 through March 2007, this nationwide multi-center prospective randomized controlled trial enrolled 103 patients 4-6 weeks after curative resection of HCC with complete recovery (52: Lipiodol, 51: Control). Follow-up was every 3 months for 1 year, then every 6 months. Primary and secondary endpoints were recurrence-free survival (RFS) and overall survival (OS), respectively, both of which were evaluated by the Kaplan-Meier technique and summarized by the hazard ratio (HR). The design was based on information obtained from a similar trial that had been conducted in Hong Kong. RESULTS: The Lipiodol group showed a small, and nonsignificant, improvement over control in RFS (HR = 0.75; 95 % confidence interval [95 % CI] 0.46-1.23; p = 0.25) and OS (HR = 0.88; 95 % CI 0.51-1.51; p = 0.64). Only two serious adverse events were reported, both with hypothyroidism caused by (131)I-lipiodol and hepatic artery dissection during angiography. CONCLUSIONS: The randomized trial provides insufficient evidence to recommend the routine use of (131)I-lipiodol in these patients.
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Antineoplásicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/cirurgia , Óleo Etiodado/uso terapêutico , Radioisótopos do Iodo/uso terapêutico , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/cirurgia , Idoso , Quimioterapia Adjuvante , Feminino , Humanos , Injeções Intra-Arteriais , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Taxa de Sobrevida , Resultado do TratamentoRESUMO
This work presents the results of a theoretical study of the electronic structure of two actinide metals,α-U andδ-Pu. We compare ourab-initioresults obtained with the recently developed self-consistent Vertex corrected GW approach with previously published experimental measurements such as photo-electron spectroscopy, for the occupied density of states, and bremsstralung isochromat spectroscopy (BIS) and inverse photo-electron spectroscopy (IPES), for the unoccupied density of states. Ourab-initioapproach includes all important relativistic effects (it is based on Dirac's equation) and it represents the first application of the Vertex corrected GW approach in the physics of actinides. Overall, our theoretical results are in good agreement with the experimental data, which supports the level of approximations which our theoretical method is based upon. By comparing our vertex corrected GW results with our results obtained with less sophisticated approaches (local density approximation and self-consistent GW) we differentiate the strength of correlation effects in Uranium and Plutonium. Also, our theoretical results allow us to elucidate the subtle differences between the previously published experimental BIS and IPES data on the unoccupied density of states inα-U.
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Guangdong-Hong Kong-Macao Greater Bay Area (GBA) has three public health systems under different systems, which plays an important role in the construction of the public health system in China. Further strengthening the construction of the public health system in the GBA will play an important reference role in the optimization and upgrade of China's public health system in the future. Based on the key consulting project of "research on the strategy of the modern public health system and capacity building in China" by Chinese Academy of Engineering, this paper deeply analyzes the current status and existing problems of public health system construction in GBA and suggests to improve and innovate the mechanisms of collaborative prevention and control of public health risks, resource coordination and joint research and result sharing, information sharing and exchange, personnel training and team building in order to comprehensively improve the capacity of public health system in GBA, and promote the construction of Healthy China.
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Saúde Pública , Humanos , China , Hong Kong , MacauRESUMO
We examined the pre-emptive analgesic effect of a cyclooxygenase (COX)-2 inhibitor in a rat surgical pain model and characterised the changes in cutaneous COX-2 around a surgical site. Thermal hyperalgesia and mechanical allodynia were tested in the rats for three days after incision and skin tissues were collected for analysis of COX-2. There was decreased expression of cutaneous COX-2 one day after surgical incision. Pre-incision injection of the COX-2 inhibitor significantly inhibited expression of COX-2 and also reduced thermal hyperalgesia (but not mechanical allodynia) compared with the post-incision COX-2-inhibitor injection group, one day after incision.
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Inibidores de Ciclo-Oxigenase 2/uso terapêutico , Manejo da Dor/métodos , Dor Pós-Operatória/prevenção & controle , Pirazóis/uso terapêutico , Sulfonamidas/uso terapêutico , Doença Aguda , Análise de Variância , Animais , Comportamento Animal , Western Blotting , Ciclo-Oxigenase 2/biossíntese , Temperatura Alta , Hiperalgesia/prevenção & controle , Masculino , Medição da Dor/efeitos dos fármacos , Limiar da Dor/efeitos dos fármacos , Estimulação Física , Ratos , Ratos Sprague-DawleyRESUMO
X-ray resonant Raman spectroscopy (XRRS), a variant of resonant inelastic x-ray scattering, has been used to investigate the two prototype systems, UF4and UO2. Both are U5f2and each is an example of 5f localized, ionic behavior and 5f localized, covalent behavior, respectively. From the M5XRRS measurements, the 5f band gap in each can be directly determined and, moreover, a clear and powerful sensitivity to 5f covalency emerges.
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One of the crucial questions of all actinide electronic structure determinations is the issue of 5f versus 6d character and the distribution of these components across the density of states. Here, a breakthough experiment is discussed, which has allowed the direct determination of the U5f and U6d contributions to the unoccupied density of states in uranium dioxide. A novel resonant inverse photoelectron and x-ray emission spectroscopy investigation of UO(2) is presented. It is shown that the U5f and U6d components are isolated and identified unambiguously.
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We investigated the photofragmentation properties of two three-membered ring heterocyclic molecules, C(2)H(4)O and C(2)H(4)S, by total and partial ion yield spectroscopy. Positive and negative ions have been collected as a function of photon energy around the C 1s and O 1s ionization thresholds in C(2)H(4)O, and around the S 2p and C 1s thresholds in C(2)H(4)S. We underline similarities and differences between these two analogous systems. We present a new assignment of the spectral features around the C K-edge and the sulfur L(2,3) edges in C(2)H(4)S. In both systems, we observe high fragmentation efficiency leading to positive and negative ions when exciting these molecules at resonances involving core-to-Rydberg transitions. The system, with one electron in an orbital far from the ionic core, relaxes preferentially by spectator Auger decay, and the resulting singly charged ion with two valence holes and one electron in an outer diffuse orbital can remain in excited states more susceptible to dissociation. A state-selective fragmentation pattern is analyzed in C(2)H(4)S which leads to direct production of S(2+) following the decay of virtual-orbital excitations to final states above the double-ionization threshold.
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We used voxel-based morphometry (VBM) to compare grey matter volume (GMV) between 20 migraine patients (five with aura and 15 without aura) with normal conventional magnetic resonance imaging findings and 33 healthy controls matched for age and sex. A separate analysis was also performed to delineate a possible correlation between the GMV changes and the headache duration or lifetime headache frequency. When compared with controls, migraine patients had significant GMV reductions in the bilateral insula, motor/premotor, prefrontal, cingulate cortex, right posterior parietal cortex, and orbitofrontal cortex (P < 0.001, uncorrected for multiple comparisons at a voxel level; corrected P < 0.05 after small volume corrections). All regions of the GMV changes were negatively correlated with headache duration and lifetime headache frequency (P < 0.05, Pearson's correlation test). We found evidence for structural grey matter changes in patients with migraine. Our findings of progressive GMV reductions in relation to increasing headache duration and increasing headache frequency suggest that repeated migraine attacks over time result in selective damage to several brain regions involved in central pain processing.
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Encéfalo/patologia , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Transtornos de Enxaqueca/patologia , Neurônios/patologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The mitochondrial protein, endonuclease G (EndoG), is one of the endonucleases implicated in DNA fragmentation during apoptosis. It has been shown to translocate from the mitochondria to the nucleus upon cell death stimuli. These observations suggest that EndoG is a mitochondrial cell death effector, and that it possibly acts as a cell death nuclease, similar to DNA fragmentation factor. To better understand the role of EndoG in development and apoptosis, we generated EndoG null mice by homologous gene targeting without disruption of D2Wsu81e. EndoG null mice are viable and develop to adulthood with no obvious abnormalities. Fibroblasts generated from the EndoG null mice show no difference in susceptibility when induced to die by a variety of intrinsic and extrinsic apoptotic stimuli. Additionally, EndoG null mice are equally sensitive to excitotoxic stress. These data suggest that EndoG is not essential for early embryogenesis and apoptosis.
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Apoptose/fisiologia , Desenvolvimento Embrionário/fisiologia , Endodesoxirribonucleases/metabolismo , Animais , Apoptose/efeitos dos fármacos , Fator de Indução de Apoptose/metabolismo , Encéfalo/embriologia , Encéfalo/enzimologia , Encéfalo/crescimento & desenvolvimento , Núcleo Celular/metabolismo , Células Cultivadas , Relação Dose-Resposta a Droga , Desenvolvimento Embrionário/genética , Endodesoxirribonucleases/genética , Etoposídeo/farmacologia , Feminino , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Imuno-Histoquímica , Metilnitronitrosoguanidina/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Camundongos Knockout , Mitocôndrias/enzimologia , Gravidez , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Translocation of apoptosis-inducing factor (AIF) from the mitochondria to the nucleus can play a major role in neuronal death elicited by oxidant stress. The time course of nuclear translocation of AIF after experimental stroke may vary with the severity of injury and may be accelerated by oxidant stress associated with reperfusion and nitric oxide (NO) production. Western immunoblots of AIF on nuclear fractions of ischemic hemisphere of male mice showed no significant increase with 1 h of middle cerebral artery occlusion and no reperfusion, whereas increases were detectable after 6 and 24 h of permanent ischemia. However, as little as 20 min of reperfusion after 1 h of middle cerebral artery occlusion resulted in an increase in nuclear AIF coincident with an increase in poly(ADP-ribose) polymer (PAR) formation. Further nuclear AIF accumulation was seen at 6 and 24 h of reperfusion. In contrast, 20 min of reperfusion after 2 h of occlusion did not increase nuclear AIF. In this case, nuclear AIF became detectable at 6 and 24 h of reperfusion. With brief occlusion of 30 min duration, nuclear AIF remained undetectable at both 20 min and 6 h and became evident only after 24 h of reperfusion. Inhibition of neuronal NO synthase attenuated formation of PAR and nuclear AIF accumulation. Gene deletion of neuronal NO synthase also attenuated nuclear AIF accumulation. Therefore, reperfusion accelerates AIF translocation to the nucleus when focal ischemia is of moderate duration (1 h), but is markedly delayed after brief ischemia (30 min). Nuclear translocation of AIF eventually occurs with prolonged focal ischemia with or without reperfusion. Neuronally-derived NO is a major factor contributing to nuclear AIF accumulation after stroke.
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Fator de Indução de Apoptose/metabolismo , Núcleo Celular/metabolismo , Ataque Isquêmico Transitório/patologia , Neurônios/enzimologia , Óxido Nítrico Sintase Tipo I/metabolismo , Animais , Comportamento Animal/fisiologia , Western Blotting , Inibidores Enzimáticos/farmacologia , Deleção de Genes , Indazóis/farmacologia , Infarto da Artéria Cerebral Média/patologia , Infarto da Artéria Cerebral Média/psicologia , Ataque Isquêmico Transitório/psicologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Óxido Nítrico Sintase Tipo I/antagonistas & inibidores , Óxido Nítrico Sintase Tipo I/genética , Poli Adenosina Difosfato Ribose/metabolismo , Transporte Proteico , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/psicologia , Frações Subcelulares/metabolismo , Fatores de TempoRESUMO
Poly(ADP-ribose) polymerases (PARPs) are members of a family of enzymes that utilize nicotinamide adenine dinucleotide (NAD(+)) as substrate to form large ADP-ribose polymers (PAR) in the nucleus. PAR has a very short half-life due to its rapid degradation by poly(ADP-ribose) glycohydrolase (PARG). PARP-1 mediates acute neuronal cell death induced by a variety of insults including cerebral ischemia, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinsonism, and CNS trauma. While PARP-1 is localized to the nucleus, PARG resides in both the nucleus and cytoplasm. Surprisingly, there appears to be only one gene encoding PARG activity, which has been characterized in vitro to generate different splice variants, in contrast to the growing family of PARPs. Little is known regarding the spatial and functional relationships of PARG and PARP-1. Here we evaluate PARG expression in the brain and its cellular and subcellular distribution in relation to PARP-1. Anti-PARG (alpha-PARG) antibodies raised in rabbits using a purified 30 kDa C-terminal fragment of murine PARG recognize a single band at 111 kDa in the brain. Western blot analysis also shows that PARG and PARP-1 are evenly distributed throughout the brain. Immunohistochemical studies using alpha-PARG antibodies reveal punctate cytosolic staining, whereas anti-PARP-1 (alpha-PARP-1) antibodies demonstrate nuclear staining. PARG is enriched in the mitochondrial fraction together with manganese superoxide dismutase (MnSOD) and cytochrome C (Cyt C) following whole brain subcellular fractionation and Western blot analysis. Confocal microscopy confirms the co-localization of PARG and Cyt C. Finally, PARG translocation to the nucleus is triggered by NMDA-induced PARP-1 activation. Therefore, the subcellular segregation of PARG in the mitochondria and PARP-1 in the nucleus suggests that PARG translocation is necessary for their functional interaction. This translocation is PARP-1 dependent, further demonstrating a functional interaction of PARP-1 and PARG in the brain.
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Química Encefálica/fisiologia , Encéfalo/enzimologia , Núcleo Celular/enzimologia , Glicosídeo Hidrolases/metabolismo , Neurônios/enzimologia , Poli(ADP-Ribose) Polimerases/metabolismo , Transporte Ativo do Núcleo Celular/fisiologia , Animais , Biomarcadores/análise , Biomarcadores/metabolismo , Compartimento Celular/genética , Linhagem Celular , Núcleo Celular/ultraestrutura , Células Cultivadas , Regulação Enzimológica da Expressão Gênica/fisiologia , Glicosídeo Hidrolases/genética , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Knockout , Mitocôndrias/enzimologia , Mitocôndrias/genética , Proteínas do Tecido Nervoso/análise , Proteínas do Tecido Nervoso/metabolismo , Neurônios/ultraestrutura , Poli(ADP-Ribose) Polimerase-1 , Poli(ADP-Ribose) Polimerases/genética , Transporte Proteico/fisiologia , Ratos , Frações SubcelularesRESUMO
Many materials have been theoretically predicted to be half-metallic, and hence suitable for use as pure spin sources in spintronic devices. Yet to date, remarkably few of these predictions have been experimentally verified. We have used spin polarized photoelectron spectroscopy to study one candidate half-metallic system, Fe(3)O(4). Such experiments are normally hampered by difficulties in producing clean stoichiometric surfaces with a polarization that is truly representative of that of the bulk. However, by utilizing higher photon energies than have traditionally been used for such experiments, we can study polarization in 'as received' samples, essentially 'looking through' the disrupted surface. High quality, strain relieved, ex situ prepared Fe(3)O(4) films have been thoroughly characterized by diffraction, transport and magnetometry studies of their crystallographic, electronic and magnetic properties. The spectroscopic results are found to agree fairly closely with previously published experimental data on in situ grown thin films and cleaved single crystals. However, despite the higher photoelectron kinetic energies of the experiment, it has not been possible to observe 100% polarization at the Fermi level. Hence, our data do not support the claim of true half-metallicity for Fe(3)O(4).
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We have studied the excited electronic structure of LaBr3(Ce) scintillator by soft x-ray spectroscopy such as x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES). The La 3d XAS and XES spectra of LaBr3(Ce) are compared with those of other La(3+) solids (LaF3, La2O3, and La metal). From this comparison, it turns out that the La 3d XAS and XES spectra from all the La(3+) solids considered here appear at almost the same energy, even though the corresponding binding energies of the 3d core holes determined by XPS (x-ray photoelectron spectroscopy) are very different. As a result, we argue that the atomic nature of the 3d94f¹ configuration created by 3d¹°4f° â 3d94f¹ x-ray absorption process in La(3+) solids is maintained via the localized 4 f (1) state, which screens the 3d core holes differently from one La(3+) solid to another.
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The electronic structure of the cerium-activated yttrium aluminum perovskite [YAP(Ce)] scintillator has been studied by core level x-ray spectroscopy and first-principles calculations. X-ray absorption and emission spectra at the oxygen K-edge of YAP(Ce) and CeO2 have been measured and compared with the calculated partial density of states. With the known band gap of CeO2, the measured oxygen K-edge absorption and emission spectra are used to construct a fixed relation between the valence and conduction bands of YAP and CeO2. This allows us to determine the fundamental band gap of YAP to be 8.1 ± 0.3 eV. A comparison between the cerium M4,5-edges x-ray absorption spectra of the YAP(Ce) and Ce model compounds (CeO2, CeF3, and Ce foils) then shows that the Ce activator is in the desired Ce(3+), with a small fraction of Ce(4+) due to oxidization at the surface. Finally, we determine that the ground state 4f(1) energy level of the Ce(3+) activator lies 1.8 ± 0.5 eV above the top of the valence band of the host YAP.