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OBJECTIVE: Coronary computed tomography angiography (CCTA) is becoming increasingly useful for the diagnosis of coronary artery disease (CAD). Coronary calcium score (CCS), epicardial fat volume (EFV), and number of coronary plaques (NoP) add important information for the risk stratification and prognosis prediction of these patients. However, evidence about their ability to predict obstructive CAD is limited. We sought to evaluate the ability of CCTA parameters in predicting obstructive CAD. PATIENTS AND METHODS: We conducted a cross-sectional, single-center study on patients at risk to develop CAD. CAD was defined as coronary stenosis > 50% after the other one (CCS, EFV and NoP were determined by CCTA). CCS was then ranked 5 severity groups: 0, 1-99, 100-399,400-999, and ≥1000. NoPs were classified in four categories: no plaques, 1-5, 6-10 and ≥10. Logistic regression analyses were performed, and statistical analysis was considered significant if p<0.05. RESULTS: Of all 540 patients (55.8±11.1 years) who met the enrolment criteria, 98 had obstructive CAD. CCS, EFV and NoP were significantly associated with the presence of obstructive CAD (p<0.0001). The area under the receiver operating characteristics (ROC) analysis revealed significant cut-off values (p<0.0001) of CCS (70.3), EFV (40.8), NoP (4) for predicting obstructive CAD. Their association proved to have an AUC of 0.969, and a specificity of 95%. A scoring system based on regression coefficients which proved to have statistical significance for obstructive CAD as further constructed. It included EFV, CCS and left ventricular ejection fraction. This scoring system significantly predicted obstructive CAD for a cut-off value of 62.46, with a NPV of 96.3%. CONCLUSIONS: The combined use of CCS, EFV and NoPs increases the predictive ability for obstructive CAD of each parameter used alone. These could be useful for developing a novel scoring system.
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Angiografia por Tomografia Computadorizada , Doença da Artéria Coronariana/diagnóstico por imagem , Adulto , Idoso , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
European standards for the protection of forests from ozone (O3) are based on atmospheric exposure (AOT40) that is not always representative of O3 effects since it is not a proxy of gas uptake through stomata (stomatal flux). MOTTLES "MOnitoring ozone injury for seTTing new critical LEvelS" is a LIFE project aimed at establishing a permanent network of forest sites based on active O3 monitoring at remote areas at high and medium risk of O3 injury, in order to define new standards based on stomatal flux, i.e. PODY (Phytotoxic Ozone Dose above a threshold Y of uptake). Based on the first year of data collected at MOTTLES sites, we describe the MOTTLES monitoring station, together with protocols and metric calculation methods. AOT40 and PODY, computed with different methods, are then compared and correlated with forest-health indicators (radial growth, crown defoliation, visible foliar O3 injury). For the year 2017, the average AOT40 calculated according to the European Directive was even 5 times (on average 1.7 times) the European legislative standard for the protection of forests. When the metrics were calculated according to the European protocols (EU Directive 2008/50/EC or Modelling and Mapping Manual LTRAP Convention), the values were well correlated to those obtained on the basis of the real duration of the growing season (i.e. MOTTLES method) and were thus representative of the actual exposure/flux. AOT40 showed opposite direction relative to PODY. Visible foliar O3 injury appeared as the best forest-health indicator for O3 under field conditions and was more frequently detected at forest edge than inside the forest. The present work may help the set-up of further long-term forest monitoring sites dedicated to O3 assessment in forests, especially because flux-based assessments are recommended as part of monitoring air pollution impacts on ecosystems in the revised EU National Emissions Ceilings Directive.
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Poluentes Atmosféricos/análise , Poluição do Ar/estatística & dados numéricos , Monitoramento Ambiental/métodos , Ozônio/análise , Conservação dos Recursos Naturais , Ecossistema , Agricultura Florestal , Florestas , Estômatos de PlantasRESUMO
INTRODUCTION: Previous series during the dissemination era of minimally invasive techniques for treatment of prostate cancer (PCa) showed a declining use of pelvic lymph node dissection (PLND). The aim of our study was to re-assess the impact of robot-assisted radical prostatectomy (RARP) on the utilization rate of PLND and its extent in the post-dissemination period. METHODS: Relying on the Surveillance Epidemiology and End Results (SEER) Medicare-linked database, 5804 patients with non-metastatic PCa undergoing open radical prostatectomy (ORP) or RARP between years 2008 and 2009 were identified. Uni- and multivariable logistic regression analyses tested the relationship between surgical approach (RARP vs. ORP) and: 1 - the rate of PLND (pNx vs. pN0-1); and 2 - the extent of PLND (limited vs. extended). RESULTS: Overall, 3357 (57.8%) patients underwent a PLND. The proportion of patients treated with PLND was significantly higher among ORP vs. RARP patients: 71.2 vs. 48.6%, respectively (P < 0.001). In addition, the median number of lymph nodes removed was significantly higher for patients treated with ORP vs. RARP: 5 vs. 4, respectively (P < 0.001). In multivariable analyses, ORP was associated with 2.7- and 1.3-fold higher odds of undergoing PLND and of receiving an extended PLND compared to RARP, respectively (both P ≤ 0.001). Stratified analyses according to disease risk classifications revealed similar trends. CONCLUSIONS: In the post-dissemination era, RARP remains associated with a decreased use of PLND and suboptimum extent. Efforts should be made to improve guideline adherence in performing a PLND whenever indicated according to tumor aggressiveness, despite surgical approach.
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Adenocarcinoma/cirurgia , Excisão de Linfonodo/estatística & dados numéricos , Linfonodos/cirurgia , Prostatectomia/métodos , Neoplasias da Próstata/cirurgia , Robótica/métodos , Idoso , Difusão de Inovações , Humanos , Modelos Logísticos , Excisão de Linfonodo/métodos , Masculino , Análise Multivariada , PelveRESUMO
AIM: Given the context that rectal tumours respond to a certain degree to radiotherapy, a necessity arises for estimating a tumour's capacity to react to radiation from the very moment of diagnostic biopsy. MATERIAL AND METHODS: We have histologically and immunohistochemically analysed tissues coming from 52 patients with rectal adenocarcinomas. RESULTS: Of the studied parameters, the ones presenting significant variation under radiotherapy in terms of statistics(p 0.05) were: colloid type (p=0.001), EGFR in the tumour(p=0.00045), EGFR in the normal epithelium (p=0.0017),VEGF in the tumour (p=0.0132) and VEGF in the tumour stroma (p=0.030). CONCLUSIONS: Our study follows the same trends as the medical literature we have consulted regarding the variation of EGFR and VEGF with radiotherapy, and the distinct note of our study relies in the observation that normal stroma in case of rectal tumors also reacts to radiotherapy, sometimes more aggressively than the tumor itself, especially in which concerns the nerve and muscle fibers.
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Adenocarcinoma/patologia , Adenocarcinoma/radioterapia , Biomarcadores Tumorais/metabolismo , Receptores ErbB/metabolismo , Neoplasias Retais/patologia , Neoplasias Retais/radioterapia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Adenocarcinoma/metabolismo , Biópsia , Feminino , Humanos , Imuno-Histoquímica , Masculino , Células Oxífilas/patologia , Valor Preditivo dos Testes , Prognóstico , Radioterapia Adjuvante , Neoplasias Retais/metabolismo , Estudos Retrospectivos , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: The distribution of BRCA mutations varies significantly between populations. The spectrum of BRCA1 and BRCA2 mutations in breast cancers in the Romanian population is incompletely known. The aim of the present study is to investigate the presence of nine BRCA mutations in patients with breast cancer identified in a surgical clinic from Bucharest. METHODS: Unrelated women diagnosed with breast cancer from Coltea Hospital (n=114) and healthy controls (n = 150) were selected for this study. Seven mutations in BRCA1 (185delAG, 5382insC, 943ins10, E1250X, 1294del40, E1373X, R1443X) and two in BRCA2 (IVS16-2A4G and 6174delT) were tested using PCR based protocols. In addition, the presence of BRCA1 185delAG, BRCA1 5382insC, BRCA2 6174delT mutations were tested with a post amplification mutation detection system, based on the ELISA method. RESULTS: Two patients with sporadic breast cancer (2%) and one patient with family history of the disease (7.14%) have the BRCA1 5382insC mutation. No other mutation was detected in patient and control groups. The mutations were not present in the control lot. CONCLUSIONS: Our results indicate that BRCA1 5382insC is a common mutation in Romanian women with breast cancer (3 114).
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Biomarcadores Tumorais/genética , Neoplasias da Mama/genética , Genes BRCA1 , Genes BRCA2 , Mutação , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/epidemiologia , Estudos de Casos e Controles , Ensaio de Imunoadsorção Enzimática , Feminino , Deleção de Genes , Predisposição Genética para Doença , Genótipo , Hospitais Universitários , Humanos , Pacientes Internados/estatística & dados numéricos , Pessoa de Meia-Idade , Mutagênese Insercional , Mutação Puntual , Reação em Cadeia da Polimerase , Prevalência , Romênia/epidemiologiaRESUMO
BACKGROUND: Atopic dermatitis (AD) results from an altered skin barrier associated with defects in the lipid composition of the skin. Dogs with AD present similar clinical symptoms to humans, and may be a useful model for investigations into AD. AIM: To analyse the changes occurring in the lipids of the stratum corneum (SC) of dogs with AE after 3 weeks of topical treatment with an emulsion containing ceramides, free fatty acids (FFAs) and cholesterol (skin lipid complex; SLC). METHODS: Nonlesional SC was collected by tape stripping from control and treated areas. Free and protein-bound lipids were purified, and the various classes were isolated by column chromatography, analysed by thin-layer chromatography and assayed. RESULTS: Ceramides, FFA and cholesterol were all found to be lower in the skin of untreated dogs with AD than in normal dogs, and the topical treatment resulted in significantly increased values for ceramides. Conversely, only trace amounts of glucosylceramides were present in normal SC, but a high concentration (27 µg per mg protein) was detected in canine atopic SC, which disappeared after treatment with SLC. There was a heterogeneous distribution of all of the lipids in the different layers of canine atopic SC, which was more pronounced for protein-bound than for free lipids. Following topical treatment, the protein-bound lipid content normalized. CONCLUSIONS: Topical treatment with SLC resulted in a significant improvement of the lipid biosynthesis of keratinocytes in atopic dogs, thereby potentially enabling the formation of a tighter epidermal barrier.
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Dermatite Atópica/veterinária , Doenças do Cão/tratamento farmacológico , Emulsões/administração & dosagem , Lipídeos/química , Pele/química , Esfingolipídeos/administração & dosagem , Administração Tópica , Animais , Dermatite Atópica/tratamento farmacológico , Dermatite Atópica/metabolismo , Doenças do Cão/metabolismo , Cães , Metabolismo dos Lipídeos/efeitos dos fármacosRESUMO
Gastrointestinal stromal tumors (GIST) are a broad category of mesenchymal, non-epithelial primary tumors of the digestive tract, located in the wall of hollow viscera, from the esophagus to the anus and often in adjacent mesentery and omentum. They are clinically unpredictable (may be discovered incidentally during an imagistic investigation or during surgery for other pathological entity, or at necropsy) and also have an unpredictable behavior (GISTs with very low risk, with low or moderate malignancy, which have benign histopathologic features but can recurr or can metastasize). The case we present here represents a rare association between a synchronous gastrointestinal stromal tumor (GIST) and multiple gastric benign and malignant tumors.
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Adenoma/patologia , Tumores do Estroma Gastrointestinal/patologia , Neoplasias Primárias Múltiplas/patologia , Pólipos/patologia , Neoplasias Gástricas/patologia , Adenocarcinoma/patologia , Adenoma/cirurgia , Idoso , Anastomose em-Y de Roux , Transformação Celular Neoplásica , Diagnóstico Diferencial , Gastrectomia , Tumores do Estroma Gastrointestinal/cirurgia , Humanos , Achados Incidentais , Masculino , Neoplasias Primárias Múltiplas/cirurgia , Pólipos/cirurgia , Neoplasias Gástricas/cirurgia , Resultado do TratamentoRESUMO
BACKGROUND: The risk of colorectal cancer (CRC) and breast cancer (BC) is influenced by polymorphisms located in the genes encoding enzymes of the folate pathway. The aim of this study was to evaluate if A66G MTRR (rs1801394) polymorphism is involved in predisposition for colorectal and breast carcinogenesis in Romanian patients. MATERIALS AND METHODS: In the present case-control study, 300 individuals divide in four groups: sporadic CRC patients (n = 120), control CRC (n = 60), BC patients (n = 60) and control BC (n = 60), were genotyped by PCR-RFLP method. RESULTS: Frequency of genotype AA was 11.7% in CRC control and 5% respectively in BC control. For cancer groups the frequency of genotype AA was 9.2% in CRC and 0% in BC. CONCLUSIONS: Study results do not demonstrate an association between A66G MTRR polymorphism and CRC or BC in Romanian patients.
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Neoplasias da Mama/genética , Neoplasias Colorretais/genética , Ferredoxina-NADP Redutase/genética , Polimorfismo Genético , Idoso , Neoplasias da Mama/enzimologia , Estudos de Casos e Controles , Neoplasias Colorretais/enzimologia , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Medição de Risco , Fatores de Risco , RomêniaRESUMO
A new study was carried out to bring more information on the effect of the potato proteins ferment. Basal keratinocytes obtained from freshly excised skin samples of two groups of five donors, a young one (25-36-year-old) and an aged one (59-70-year-old) were established in culture. The results showed a downward trend in the content of all lipid fractions in untreated keratinocytes of aged donors when compared with young ones. We found major differences in the response of keratinocytes to potato proteins ferment treatment between young and old donors. Whereas the lipid content of cells from young donors increased either moderately or actually decreased in some cases in comparison with the untreated controls, the lipid biosynthesis was strongly stimulated in aged donors' keratinocytes whose lipid contents globally became close to those found in young donors. However, the changes elicited by potato proteins ferment treatment were not seen at the same extent for all lipid classes. Cholesterol content increased up to three-fold and alpha-hydroxy fatty acids were augmented up to seven-fold, whereas the increase in normal fatty acids was quite moderate. In sphingolipids labelled by incubation of keratinocytes in culture medium containing [(14)C]-serine, ceramides and glucosylceramides in cells from aged donors showed the highest uptake of radioactivity, with somewhat less incorporation in sphingomyelin and gangliosides. Therefore, it seems that potato proteins ferment has a much more potent stimulatory activity on the lipid biosynthesis of basal keratinocytes of aged donors, thereby normalizing the cellular lipid content that obviously decreases along with ageing. Although our results were obtained only with basal keratinocytes in this study, potato proteins ferment could be beneficial to maintain an efficient skin barrier in ageing people, provided that the peptides can get through to the basal membrane upon topical application.
Assuntos
Envelhecimento/metabolismo , Queratinócitos/efeitos dos fármacos , Peptídeos/farmacologia , Proteínas de Plantas/química , Solanum tuberosum/química , Esfingolipídeos/biossíntese , Adulto , Idoso , Células Cultivadas , Feminino , Humanos , Hidrólise , Queratinócitos/metabolismo , Masculino , Pessoa de Meia-IdadeRESUMO
Adenoid cystic carcinoma is a rare type of breast carcinoma with a good prognosis. It represents less than 0,1% of breast carcinomas. We present two cases of adenoid cystic carcinoma diagnosed in the Surgical Department of Coltea Hospital in the last 3 years. The first case is a 66 years old patient with a breast tumor that has clinical and imagistic features compatible with a benign diagnosis. The frozen sections established the diagnosis of adenoid cystic carcinoma, confirmed by histopathologic examination of paraffin embedded tissue and immunohistochemistry. The second case is a 68 years old patient with a breast tumor located in the central quadrant of the left breast, with skin infiltration. Preoperatory fine needle aspiration is sugestive of a papillary tumor, so the cytologic exam cannot establish malignancy. The frozen sections established the diagnosis of ductal invasive carcinoma and histopathologic examination of paraffin embedded tissue and immunohistochemistry established the diagnosis of adenoid cystic carcinoma associated with ductal invasive carcinoma grade I and adenomyoepitelioma. The cytology had a false papillary aspect, in fact there was amorphous material contained in pseudoluminal spaces. In both cases the treatment was surgical resection with tumor excision and free resection margins. In the second case lymphadenectomy was also performed.
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Adenomioepitelioma/patologia , Neoplasias da Mama/patologia , Carcinoma Adenoide Cístico/patologia , Neoplasias Primárias Múltiplas/patologia , Adenomioepitelioma/cirurgia , Idoso , Biópsia por Agulha , Neoplasias da Mama/cirurgia , Carcinoma Adenoide Cístico/cirurgia , Carcinoma Ductal de Mama/patologia , Diagnóstico Diferencial , Feminino , Humanos , Excisão de Linfonodo , Mastectomia , Estadiamento de Neoplasias , Neoplasias Primárias Múltiplas/cirurgia , Resultado do TratamentoRESUMO
We present a quantitative surface x-ray analysis of the buried Ni/Cu(001) interface structure after deposition of 3 and 5 monolayers of Ni at room temperature. Interface mixing is found where 27+/-10% of top layer Cu atoms are exchanged by Ni. Atomic scale simulations reveal a kinetic pathway for the Ni/Cu-exchange process and explain the observed limited degree of intermixing. A disperse distribution of Ni within the Cu surface with a preferential Ni-Ni separation of 3-4 nearest neighbor distances is determined.
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UNLABELLED: Porous scaffolds based on collagen and chitosan have been obtained from mixed bio-polymeric solutions and mixture freeze-drying method in the purpose of using them as materials for post-burns tissue regeneration. MATERIAL AND METHOD: Soluble collagen from bovine leather was obtained by acid-base extraction (isoelectric pH = 4.82). Two types of chitosan (CS I, M(w) = 755.900, de-acetylating degree of 79.2% and CS II, M(w) = 309.900, de-acetylating degree of 79.7%), were provided by Vascon Co., Canada. Various compositions were prepared and then structurally and morphologically characterized. In vitro degradation studies were performed in buffered collagenase or chitosan solutions, respectively, and the kinetic data were analysed. Materials effect on the tissue regeneration was tested on heat-induced burns in Wistar rats by covering the damaged tissue with collagen-chitosan scaffolds for a period of 28 days. Materials were changed every 7 days. At the end of the follow-up period skin tissue samples were harvested for histological investigation. RESULTS: By freeze-drying of collagen-chitosan solutions porous scaffolds were obtained with a lamellar morphology and porosity closer to chitosan than to collagen. In vitro degradation tests in simulated body fluid with collagenase revealed a decrease of the degradation rate of the collagen by mixing with chitosan. By using chitosan with lower molecular weight the degradation rate of the materials was decreased too, and the influence of the proportion of chitosan in composition diminished; stronger interactions between polymers hinder the enzyme diffusion to the following amino-acids groups: glycine - leucine (Gly-Leu), glycine - isoleucine (Gly-Ile), alanine-proline-glycine/leucine (-Ala-Pro-Gly-/-Leu-). In vivo tests and histological examination revealed a differentiated repair process of the post-combustion wounds in accordance with the scaffold-type influence. CONCLUSION: Scaffolds based on collagen and chitosan are biocompatible materials with promising results for tissue regeneration of the wounds.
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Materiais Biocompatíveis/química , Queimaduras/terapia , Quitosana/química , Colágeno/química , Engenharia Tecidual/métodos , Alicerces Teciduais , Alanina/química , Animais , Bovinos , Modelos Animais de Doenças , Glicina/química , Leucina/química , Teste de Materiais/métodos , Poliésteres/química , Porosidade , Prolina/química , Ratos , Ratos Wistar , CicatrizaçãoRESUMO
The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films.
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Several products are known to inhibit the biosynthesis of ceramides and glucosylceramides, but very few stimulate this process. We studied the influence of a hydrolysate of potato proteins (Lipidessence) in vitro on the sphingolipid metabolism of normal human epidermal keratinocytes. By measuring growth with the thymidine uptake assay, it was seen that Lipidessence, added in the culture medium up to an 8% concentration, did not change significantly the proliferation rate of keratinocytes, but beyond this concentration a progressive dose-dependent inhibition of growth was noticeable. Following incubation of cells with the product at 5% and 10% concentrations for 2 days, the lipids were extracted. The different lipid classes were separated by fractionation on columns of aminopropyl silica gel and analyzed by high-performance thin-layer chromatography. When keratinocytes were cultivated in the presence of Lipidessence, the biosynthesis of cholesterol, phosphatidylcholine, phosphatidylserine and gangliosides was stimulated, and a major increase was noticeable in the biosynthesis of free fatty acids, free ceramides, glucosylceramide and sphingomyelin. Radioactive [(14)C]-serine was used as a precursor of sphingoid bases to study sphingolipid biosynthesis. After migration of lipid fractions on thin-layer plates, autoradiography showed that free ceramides and glucosylceramide were labeled, thus suggesting that de novo biosynthesis was accounting for the increased cellular content in sphingolipids.
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We present the first structure determination by surface x-ray diffraction during the restructuring of a model catalyst under reaction conditions, i.e., at high pressure and high temperature, and correlate the restructuring with a change in catalytic activity. We have analyzed the Pt(110) surface during CO oxidation at pressures up to 0.5 bar and temperatures up to 625 K. Depending on the pressure ratio, we find three well-defined structures: namely, (i) the bulk-terminated Pt(110) surface, (ii) a thin, commensurate oxide, and (iii) a thin, incommensurate oxide. The commensurate oxide only appears under reaction conditions, i.e., when both and CO are present and at sufficiently high temperatures. Density functional theory calculations indicate that the commensurate oxide is stabilized by carbonate ions (CO3(2-)). Both oxides have a substantially higher catalytic activity than the bulk-terminated Pt surface.
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Although Meckel's diverticulum is the most common congenital abnormality of the gastrointestinal tract, complications in adults are rare, especially in the elderly. Lower gastrointestinal bleeding as a result of Meckel's diverticulum with ectopic gastric mucosa is unusual among the elderly. The case we report involved a 69 year old man with gastrointestinal hemorrhage found to be due a stromal tumor developed on Meckel's diverticulum. We considered our case interesting because of its rarity and of preoperative diagnosis difficulty.
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Hemorragia Gastrointestinal/etiologia , Tumores do Estroma Gastrointestinal/complicações , Tumores do Estroma Gastrointestinal/diagnóstico , Divertículo Ileal/complicações , Divertículo Ileal/diagnóstico , Idoso , Diagnóstico Diferencial , Hemorragia Gastrointestinal/cirurgia , Tumores do Estroma Gastrointestinal/patologia , Tumores do Estroma Gastrointestinal/cirurgia , Humanos , Neoplasias do Íleo/complicações , Neoplasias do Íleo/diagnóstico , Neoplasias do Íleo/cirurgia , Masculino , Divertículo Ileal/patologia , Divertículo Ileal/cirurgia , Resultado do TratamentoRESUMO
Rabi nutations of a single nuclear spin in a solid have been observed. The experiments were carried out on a single electron and a single 13C nuclear spin of a single nitrogen-vacancy defect center in diamond. The system was used for implementation of quantum logical NOT and a conditional two-qubit gate (CROT). Density matrix tomography of the CROT gate shows that the gate fidelity achieved in our experiments is up to 0.9, good enough to be used in quantum algorithms.
RESUMO
Rabi nutations and Hahn echo modulation of a single electron spin in a single defect center have been observed. The coherent evolution of the spin quantum state is followed via optical detection of the spin state. Coherence times up to several microseconds at room temperature have been measured. Optical excitation of the spin states leads to decoherence. Quantum beats between electron spin transitions in a single spin Hahn echo experiment are observed. A closer analysis reveals that beats also result from the hyperfine coupling of the electron spin to a single 14N nuclear spin. The results are analyzed in terms of a density matrix approach of an electron spin interacting with two oscillating fields.
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Gangliosides are glycosphingolipids made of hydrophobic ceramides coupled to hydrophilic sialylated oligosaccharides. They belong to lipid rafts located on the outer leaflet of the plasma membrane and their oligosaccharide moieties are exposed on the cell surface. Gangliosides are shed as monomeric molecules from the plasma membrane by a largely unknown mechanism into the extracellular medium and they are synthesized de novo by the cells. The shed gangliosides bind to lipoproteins from which they are taken up by erythrocytes and leukocytes. The ganglioside enrichment of leukocytes results in an alteration in the transduction of activation signals, leading to an impaired cellular immunity.
Assuntos
Gangliosídeos/fisiologia , Lipídeos , Pele/imunologia , Citocinas , Gangliosídeos/análise , Gangliosídeos/química , Humanos , Imunidade Celular , Leucócitos/química , Leucócitos/metabolismo , Estrutura Molecular , Linfócitos T/química , Linfócitos T/imunologiaRESUMO
A2B5 antibody was found to strongly label frozen sections of human head and neck squamous cell carcinomas. The low amount of glycolipids (c-series gangliosides and sulfatides) purified from the same tumors and reactive with A2B5 by immunostaining on thin-layer plates could not account for the high level of tissue labeling. Proteins were extracted from both normal tissues and squamous cell carcinomas and analyzed by Western blot with A2B5 antibody on PVDF membranes. The antibody was found to stain a set of glycoproteins with two major bands at 55 and 76 kDa present in normal tissues and overexpressed in carcinomas. Staining was abolished by prior treatment of the PVDF membranes either with Arthrobacter ureafaciens neuraminidase or with a solution of 10 mM periodate that is known to destroy carbohydrates. Our results show that the carbohydrate epitope recognized by A2B5 antibody can be displayed by both glycolipids and glycoproteins.