998 resultados para Secondary Electrons Emission
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It has been demonstrated in earlier studies that patients with a cochlear implant have increased abilities for audio-visual integration because the crude information transmitted by the cochlear implant requires the persistent use of the complementary speech information from the visual channel. The brain network for these abilities needs to be clarified. We used an independent components analysis (ICA) of the activation (H2 (15) O) positron emission tomography data to explore occipito-temporal brain activity in post-lingually deaf patients with unilaterally implanted cochlear implants at several months post-implantation (T1), shortly after implantation (T0) and in normal hearing controls. In between-group analysis, patients at T1 had greater blood flow in the left middle temporal cortex as compared with T0 and normal hearing controls. In within-group analysis, patients at T0 had a task-related ICA component in the visual cortex, and patients at T1 had one task-related ICA component in the left middle temporal cortex and the other in the visual cortex. The time courses of temporal and visual activities during the positron emission tomography examination at T1 were highly correlated, meaning that synchronized integrative activity occurred. The greater involvement of the visual cortex and its close coupling with the temporal cortex at T1 confirm the importance of audio-visual integration in more experienced cochlear implant subjects at the cortical level.
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Fluorescence cystoscopy enhances detection of early bladder cancer. Water used to inflate the bladder during the procedure rapidly contains urine, which may contain fluorochromes. This frequently degradesfluorescence images. Samples of bladder washout fluid (BWF) or urine were collected (15 subjects). We studiedtheir fluorescence properties and assessed changes induced by pH (4 to 9) and temperature (15°C to 41°C).A typical fluorescence spectrum of BWF features a main peak (excitation/emission: 320∕420 nm, FWHM =50∕100 nm) and a weaker (5% to 20% of main peak intensity), secondary peak (excitation/emission: 455∕525 nm, FWHM = 80∕50 nm). Interpatient fluctuations of fluorescence intensity are observed. Fluorescence intensity decreases when temperature increases (max 30%) or pH values vary (max 25%). Neither approach is compatible with clinical settings. Fluorescence lifetime measurements suggest that 4-pyridoxic acid/riboflavin is the most likely molecule responsible for urine's main/secondary fluorescence peak. Our measurements give an insight into the spectroscopy of the detrimental background fluorescence. This should be included in the optical design of fluorescence cystoscopes. We estimate that restricting the excitation range from 370-430 nm to 395-415 nm would reduce the BWF background by a factor 2.
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Hypersensitivity pneumonitis (HP) is an immunologically mediated lung disease due to the repetitive inhalation of antigens. Most new cases arise from residential exposures, notably to birds, and are thus more difficult to recognise. The present authors report a 59-yr-old male who complained of dyspnoea and cough while being treated with amiodarone. Pulmonary function tests revealed restriction and obstruction with low diffusing lung capacity for carbon monoxide and partial pressure of oxygen. A high-resolution computed tomography chest scan and bronchoalveolar lavage showed diffuse bilateral ground-glass attenuation and lymphocytic alveolitis, respectively. Initial diagnosis was amiodarone pulmonary toxicity, but because of a rapidly favourable evolution, this diagnosis was questioned. A careful environmental history revealed a close contact with lovebirds shortly before the onset of symptoms. Precipitins were strongly positive against lovebird droppings, but were negative against other avian antigens. The patient was diagnosed with hypersensitivity pneumonitis to lovebirds. Avoidance of lovebirds and steroid treatment led to rapid improvement. The present observation identifies a new causative agent for hypersensitivity pneumonitis and highlights the importance of a thorough environmental history and of searching for precipitins against antigens directly extracted from the patient's environment. These two procedures should allow a more precise classification of some cases of pneumonitis, and thus might avoid progression of active undiagnosed hypersensitivity pneumonitis to irreversible fibrosis or emphysema.
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We report the case of a 6-month-old infant who presented with a complete duplication of the large intestine, debuting clinically with acute abdomen and severe metabolic disorders. We discuss the pathogenesis and morphology of the lesions, diagnostic difficulties and peculiarities of surgical treatment.
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BACKGROUND Migraine is a chronic neurologic disease that can severely affect the patient's quality of life. Although in recent years many randomised studies have been carried out to investigate the effectiveness of acupuncture as a treatment for migraine, it remains a controversial issue. Our aim is to determine whether acupuncture, applied under real conditions of clinical practice in the area of primary healthcare, is more effective than conventional treatment. METHODS/DESIGN The design consists of a pragmatic multi-centre, three-armed randomised controlled trial, complemented with an economic evaluation of the results achieved, comparing the effectiveness of verum acupuncture with sham acupuncture, and with a control group receiving normal care only. Patients eligible for inclusion will be those presenting in general practice with migraine and for whom their General Practitioner (GP) is considering referral for acupuncture. Sampling will be by consecutive selection, and by randomised allocation to the three branches of the study, in a centralised way following a 1:1:1 distribution (verum acupuncture; sham acupuncture; conventional treatment). Secondly, one patient in three will be randomly selected from each of the acupuncture (verum or sham) groups for a brain perfusion study (by single photon emission tomography). The treatment with verum acupuncture will consist of 8 treatment sessions, once a week, at points selected individually by the acupuncturist. The sham acupuncture group will receive 8 sessions, one per week, with treatment being applied at non-acupuncture points in the dorsal and lumbar regions, using the minimal puncture technique. The control group will be given conventional treatment, as will the other two groups. DISCUSSION This trial will contribute to available evidence on acupuncture for the treatment of migraine. The primary endpoint is the difference in the number of days with migraine among the three groups, between the baseline period (the 4 weeks prior to the start of treatment) and the period from weeks 9 to 12. As a secondary aspect, we shall record the index of laterality and the percentage of change in the mean count per pixel in each region of interest measured by the brain perfusion tomography, performed on a subsample of the patients within the real and sham acupuncture groups. TRIAL REGISTRATION Current Controlled Trials ISRCTN98703707.
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Purpose : Secondary malignancies (SM) are a known long-‐term problem in children surviving brain tumors. We report on two unusual cases of SM observed after treatment of ependymoma. Case reports : 1. The first case is a female survivor of a low-‐grade ependymoma (Grade II). She had been treated at the age of 3 months with surgery and chemotherapy. A relapse of the primary tumor happened two years later, which was completely removed and treated with local radiotherapy to the posterior fossa. Fifteen years after the first cancer, she developed a pontine glioma near the location of the previous radiotherapy. 2. The second case is a femal survivor of an ependymoma (Grade III) which was removed and irradiated when she was 4 years old. The child developed a pontine glioma near the location of the previous radiotherapy ten years after the diagnosis of the first cancer. Further extension of the disease showed after biopsy PNET-‐ like features. Both patients passed away. Discussion and Conclusion : Second malignant neoplasia is a rare phenomenon and this risk should not overshadow the great success in treating cancer of childhood. Among the studied risk factors, young age and radiotherapy are well established. The reported patients were followed annually to ensure their remission and both developed symptoms and an unusual unreported secondary cancer a few months after the annual monitoring that was considered as normal. This issue highlights the complexity of monitoring cancer survivors and raises the question of the best way for their long-‐term follow-‐up.
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In Pseudomonas aeruginosa, the catabolite repression control (Crc) protein repressed the formation of the blue pigment pyocyanin in response to a preferred carbon source (succinate) by interacting with phzM mRNA, which encodes a key enzyme in pyocyanin biosynthesis. Crc bound to an extended imperfect recognition sequence that was interrupted by the AUG translation initiation codon.
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Positron emission tomography is a functional imaging technique that allows the detection of the regional metabolic rate, and is often coupled with other morphological imaging technique such as computed tomography. The rationale for its use is based on the clearly demonstrated fact that functional changes in tumor processes happen before morphological changes. Its introduction to the clinical practice added a new dimension in conventional imaging techniques. This review presents the current and proposed indications of the use of positron emission/computed tomography for prostate, bladder and testes, and the potential role of this exam in radiotherapy planning.
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We characterize divergence times, intraspecific diversity and distributions for recently recognized lineages within the Hyla arborea species group, based on mitochondrial and nuclear sequences from 160 localities spanning its whole distribution. Lineages of H. arborea, H. orientalis, H. molleri have at least Pliocene age, supporting species level divergence. The genetically uniform Iberian H. molleri, although largely isolated by the Pyrenees, is parapatric to H. arborea, with evidence for successful hybridization in a small Aquitanian corridor (southwestern France), where the distribution also overlaps with H. meridionalis. The genetically uniform H. arborea, spread from Crete to Brittany, exhibits molecular signatures of a postglacial range expansion. It meets different mtDNA clades of H. orientalis in NE-Greece, along the Carpathians, and in Poland along the Vistula River (there including hybridization). The East-European H. orientalis is strongly structured genetically. Five geographic mitochondrial clades are recognized, with a molecular signature of postglacial range expansions for the clade that reached the most northern latitudes. Hybridization with H. savignyi is suggested in southwestern Turkey. Thus, cryptic diversity in these Pliocene Hyla lineages covers three extremes: a genetically poor, quasi-Iberian endemic (H. molleri), a more uniform species distributed from the Balkans to Western Europe (H. arborea), and a well-structured Asia Minor-Eastern European species (H. orientalis).
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Les maladies cardiovasculaires restent la cause de mortalité la plus élevée dans le monde occidental. Il s'agit d'un processus long et complexe, dont l'infarctus du myocarde et la mort cardiaque ne sont que la fin d'un spectrum. La perfusion myocardique joue un rôle central dans l'évolution de la maladie et survient chronologiquement en amont de la dysfonction diastolique et systolique, ainsi que de l'infarctus du myocarde. Une meilleure compréhension de la Physiopathologie sous-jacente est cruciale dans le diagnostique et la prise en charge du patient. Dans ce sens, ce travail tente d'évaluer l'apport de l'évaluation de la perfusion myocardique évaluée par la tomographic à émission de positron (PET/CT) quant à la prédiction d'événements cardiovasculaires. De plus, l'apport de l'évaluation quantitative par rapport à l'évaluation qualitative a été démontré dans ce travail. Nous avons utilisé un radiotraceur unique au regard de ses caractéristiques. En effet, Le Rubidium-82 est un traceur qui ne nécessite pas d'un cyclotron pour sa fabrication, dès lors qu'il est produit par un générateur, rendant ainsi sa disponibilité un atout et un avantage potentiel lors de futurs implémentations à plus grande échelle. Ce travail démontre la supériorité de l'analyse de perfusion myocardique quantitative par rapport à l'analyse traditionnelle qualitative, ce qui n'était pas encore confirmé avec le Rubidium-82. Les résultats montrent une démarcation significative entre les différentes valeurs de perfusion quantitative/absolue, permettant de distinguer différentes populations plus ou moins à risque en terme de prédiction d'événements cardiaques futurs. Il est intéressant de noter que dans un modèle combinant l'analyse qualitative et quantitative proposé dans ce travail, l'inclusion des résultats les plus ischémiques obtenus par l'analyse qualitative avec les résultats de perfusion les plus bas en terme de flux myocardique absolu (analyse quantitative) démarque une population à très bas risque d'événements cardiovasculaires majeurs, une prédiction pouvant être observée surplus de 1'000 jours. Ces résultats forment un ajout significatif quant à l'évaluation de la perfusion myocardique par la médecine nucléaire, notamment par ce model intégratif proposé, lequel permet une prédiction précise et contributive dans le cadre de futurs événements cardiovasculaires majeurs.
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The classical description of Si oxidation given by Deal and Grove has well-known limitations for thin oxides (below 200 Ã). Among the large number of alternative models published so far, the interfacial emission model has shown the greatest ability to fit the experimental oxidation curves. It relies on the assumption that during oxidation Si interstitials are emitted to the oxide to release strain and that the accumulation of these interstitials near the interface reduces the reaction rate there. The resulting set of differential equations makes it possible to model diverse oxidation experiments. In this paper, we have compared its predictions with two sets of experiments: (1) the pressure dependence for subatmospheric oxygen pressure and (2) the enhancement of the oxidation rate after annealing in inert atmosphere. The result is not satisfactory and raises serious doubts about the model’s correctness
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Several airline consolidation events have recently been completed both in Europe and in the United States. The model we develop considers two airlines operating hub-and-spoke networks, using different hubs to connect the same spoke airports. We assume the airlines to be vertically differentiated, which allows us to distinguish between primary and secondary hubs. We conclude that this differentiation in air services becomes more accentuated after consolidation, with an increased number of flights being channeled through the primary hub. However, congestion can act as a brake on the concentration of flight frequency in the primary hub following consolidation. Our empirical application involves an analysis of Delta s network following its merger with Northwest. We find evidence consistent with an increase in the importance of Delta s primary hubs at the expense of its secondary airports. We also find some evidence suggesting that the carrier chooses to divert traffic away from those hub airports that were more prone to delays prior to the merger, in particular New York s JFK airport. Keywords: primary hub; secondary hub; airport congestion; airline consolidation; airline networks JEL Classi fication Numbers: D43; L13; L40; L93; R4
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We diagnosed a non-small cell lung carcinoma in a 49-year-old female patient with the histopathological diagnosis of stage IIIB mixed bronchioloalveolar and papillary adenocarcinoma with extensive micropapillary feature, which was not visualized on the preoperative multimodality imaging with positron emission tomography (PET) and computed tomography (CT). The micropapillary component characterized by a unique growth pattern with particular morphological features can be observed in all subtypes of lung adenocarcinoma. Micropapillary component is increasingly recognized as a distinct entity associated with higher aggressiveness. Even the most modern multimodality PET/CT imaging technology may fail to adequately visualize this important component with highly relevant prognostic implications. Thus, the pathologist needs to consciously look for a micropapillary component in the surgical specimen or in preoperative biopsies or cytology. This may have potential future treatment implications, as adjuvant or neoadjuvant chemotherapy may be of relevance, even in the early stages of the disease.