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Electron energy-loss spectroscopy was used to characterize the boron profile and its coordination (BIII and BIV), along the complex alteration layer of glass samples altered for 511 days at 50 °C in solution containing FeCl2, MgCl2 and/or CaCl2. To reach this goal, the impact of both TEM operating conditions and sample preparation on the determination of the boron coordination was first studied using mineralogical and pristine glasses reference samples. Then, the boron concentration profiles were characterized in the glass alteration layer. These profiles were found to be S-shaped with a thickness around forty nanometers. The proportion of BIII was found to decrease with the boron total concentration (from the pristine glass to the gel layer), which suggests a higher bonding strength for BIV bonds than that of BIII bonds under the alteration conditions. These findings are of tremendous interest to advance further in the understanding of glass alteration mechanisms.
Assuntos
Boro/química , Vidro/química , Espectroscopia de Perda de Energia de Elétrons/métodos , Vidro/análise , Teste de Materiais , Minerais/análiseRESUMO
A new high-temperature detector dedicated to the collection of backscattered electrons is used in combination with heating stages up to 1050°C, in high-vacuum and low-vacuum modes in order to evaluate its possibilities through signal-to-noise ration measurements and different applications. Four examples of material transformations occurring at high temperature are herein reported: grain growth during annealing of a rolled platinum foil, recrystallisation of a multiphased alloy, oxidation of a Ni-based alloy and complex phase transformations occurring during the annealing of an Al-Si coated boron steel. The detector could be potentially adapted to any type of SEM and it offers good opportunities to perform high-temperature experiments in various atmospheres.
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INTRODUCTION: Augmented reality (AR) technologies can enrich the real environment with visual data, which has potential benefits for optimising the operator's working process. It offers the possibility to provide context-sensitive information independently of the user's location and position. Data are presented to the dominant eye on a semi-transparent mirror using a head-mounted display (HMD) unit that works with retinal laser technology. In this study the potential benefits and drawbacks of this new AR technology were evaluated. MATERIALS AND METHODS: 45 participants without any visual impairment were randomly assigned to 3 groups and completed a variety of tasks during a simulated working day. Group 1 received conventional working aids (paper-based documents) to support the task processing. Group 2 additionally wore an HMD unit that was switched off. Group 3 wore a functioning HMD without any additional aids. Evaluation was carried out by means of a standardised questionnaire (BMS) and a concentration test ("d2 Aufmerksamkeits-Belastungs-Test"). RESULTS: No significant differences between the 3 groups were found in terms of mental strain, concentration-test performance and physical or mental complaints reported in a follow-up interview. Around 20 % of the subjects noticed a higher pressure and blurred vision in both eyes as well as headaches. Half of the participants complained about deficiencies concerning the ergonomic hardware design of the AR system. DISCUSSION: Changes in objective ophthalmological investigation parameters were not observed. Subjects reported reduced acceptance of the HMD based on non-ophthalmological reasons, for example, the weight of the unit or the length of the cable. However, for some specific working tasks, advantages in process optimisation and operator support were observed.
Assuntos
Atenção , Recursos Audiovisuais , Desempenho Psicomotor , Interface Usuário-Computador , Visão Monocular , Acuidade Visual , Adulto , Automóveis , Comportamento do Consumidor , Desenho de Equipamento , Ergonomia , Feminino , Humanos , Indústrias , Masculino , PesquisaRESUMO
[123I]IBZM is a new radioactive labelled ligand which has a high affinity and specificity to D2-dopamine receptors. The in vivo kinetics of [123I]IBZM were studied in patients with unilateral and bilateral accentuated idiopathic Parkinson's disease. The uptake in the basal ganglias and the imaging properties of this D2 receptor antagonist as a radiopharmaceutical for SPECT examinations had to be investigated. 5 patients, aged 42-66 years, (2 m/3 f) were examined. Each patient received 185 MBq [123I]IBZM intravenously. Blood samples were taken 0-120 min post injection (p.i.) and time activity curves were plotted. Three SPECT examinations were performed (I: 30-50 min; II: 50-70 min; and III: 70-90 min p.i.). The count rates (counts/pixel) in the basal ganglias and the cerebellum were measured for each SPECT series on transverse slices using the region-of-interest technique. The time-activity curve of [123I]IBZM shows a rapid decline in plasma during the first 10 min followed by a plateau until 120 min after injection. The SPECT examinations demonstrate the highest count rate in the basal ganglia during SPECT series III (i.e., 70-90 min p.i.). The side-to-side difference of the count rates were in the range of 3% in four patients, and 10% in one patient. The biokinetic data of [123I]IBZM make this substance capable as a radiopharmaceutical for SPECT examinations. The basal ganglia are best visualized 70-90 min p.i., thus [123I]IBZM seems to be a promising imaging agent for diseases of the D2-dopaminergic receptor system.
Assuntos
Benzamidas/farmacologia , Encéfalo/diagnóstico por imagem , Antagonistas de Dopamina , Doença de Parkinson/diagnóstico por imagem , Pirrolidinas/farmacologia , Tomografia Computadorizada de Emissão de Fóton Único , Adulto , Idoso , Benzamidas/farmacocinética , Barreira Hematoencefálica , Encéfalo/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/metabolismo , Pirrolidinas/farmacocinética , Receptores de Dopamina D2RESUMO
Twenty-three patients with multiple sclerosis were studied during an acute episode and again 4 weeks later. Whereas the patients' clinical condition improved significantly (Kurtzke DSS: from 3.9 (SD 1.4) to 3.3 (SD 1.5), P less than 0.001), the conventional power spectra of the resting EEG showed no marked changes. Following a 10-min EEG recording under resting conditions the patients performed a visuomotor tracking task, during which a further EEG recording was made. The frequency of the subvigilant non-A epochs of Loomis et al. as calculated for each minute of the resting recording was taken as the basis for evaluating the EEG dynamics of vigilance. A comparison during and after relapse showed differences in the time courses of the numbers of non-A epochs. While the non-A epochs were not time dependent in the acute phase, remission was characterized by a steady increase in non-A epochs across the 10 min of the recording period. This change in the dynamics of vigilance, which approximates a physiological pattern, was accompanied by an improvement in visuomotor tracking performance. Comparison of the power spectra of the EEG recorded during the tracking task showed a bifrontal increase in absolute alpha power during remission.
Assuntos
Nível de Alerta/fisiologia , Atenção/fisiologia , Eletroencefalografia , Esclerose Múltipla/fisiopatologia , Desempenho Psicomotor/fisiologia , Processamento de Sinais Assistido por Computador , Doença Aguda , Adulto , Ritmo alfa , Córtex Cerebral/fisiopatologia , Eletroencefalografia/instrumentação , Potenciais Evocados Visuais/fisiologia , Feminino , Humanos , Masculino , Esclerose Múltipla/diagnósticoRESUMO
Cerebral MRI and CT findings were compared with various cerebrospinal fluid (CSF) parameters and clinical features in 75 patients with multiple sclerosis (MS). There were positive correlations between CSF albumin as a parameter of blood-brain barrier function and morphological parameters, namely the number of nonperiventricular foci and periventricular involvement demonstrated by MRI and ventricular enlargement as shown by CT. Apart from positive correlations between the number of nonperiventricular foci and CSF levels of IgA and IgG, including the IgG synthetic rate, no other correlations were found between CSF parameters (leucocyte count and immunoglobulin concentrations) and morphological findings. The unremitting-progressive type of MS was distinguished from the relapsing-remitting form by a lower CSF leucocyte count and a higher degree of disability, but there was no difference between the morphological findings in the two forms. Positive correlations were found between degree of disability and both periventricular involvement in the MRI and CT evidence of ventricular enlargement. In terms of correlations with the duration of disease, cerebral MRI proved to be far superior to CSF evaluations.
Assuntos
Esclerose Múltipla/fisiopatologia , Adolescente , Adulto , Idoso , Albuminas/líquido cefalorraquidiano , Barreira Hematoencefálica , Feminino , Humanos , Imunoglobulina A/líquido cefalorraquidiano , Imunoglobulina G/biossíntese , Imunoglobulina G/líquido cefalorraquidiano , Contagem de Leucócitos , Leucócitos/análise , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/líquido cefalorraquidiano , Esclerose Múltipla/diagnóstico , Esclerose Múltipla/patologia , Fatores de Tempo , Tomografia por Raios XRESUMO
23 Patients with multiple sclerosis were subjected to a visuomotor tracking test, consisting of subtests of different task difficulty, while being in a state of acute exacerbation and four weeks later, while exhibiting a more or less pronounced clinical remission (Kurtzke DSS 3.9 (+/- 1.4) vs. 3.3 (+/- 1.5); p less than 0.001). Corresponding to this the tracking test performances improved, the difference being significant only with the easiest test run. The tracking performances correlated with the Kurtzke scores, both for the acute state and for the remitted state, the highest correlation showing up for the easiest test run. Hence, the visuomotor tracking test seems to be suited to measure functional deficits and to evaluate the efficiency of therapeutic procedures.
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Hormônio Adrenocorticotrópico/uso terapêutico , Movimentos Oculares/efeitos dos fármacos , Esclerose Múltipla/tratamento farmacológico , Desempenho Psicomotor/efeitos dos fármacos , Acompanhamento Ocular Uniforme/efeitos dos fármacos , Adulto , Avaliação da Deficiência , Feminino , Humanos , Masculino , Tempo de Reação/efeitos dos fármacosRESUMO
Forty-six patients with multiple sclerosis were rated with respect to their psychologic symptoms, and magnetic resonance imaging was performed. A significant correlation between the cerebral multiple sclerosis manifestations and the psychologic scores was found. The periventricular and frontal lesions seem to be the most important lesions for the psychologic symptoms of patients with multiple sclerosis.
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Afeto , Encéfalo/patologia , Cognição , Impulso (Psicologia) , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico , Humanos , Esclerose Múltipla/patologia , Esclerose Múltipla/psicologia , Escalas de Graduação PsiquiátricaRESUMO
In 40 patients with multiple sclerosis, 11 of whom presented with their first disease manifestation, cortical somatosensory evoked potentials following median and tibial nerve stimulation were examined. 45 percent of the patients with first manifestation had at least one pathological SEP, while 79 percent of the patients with longer course of the illness showed pathological SEPs. The group of patients with first manifestation differs significantly in this aspect from the group of those patients with longer duration of the illness. The occurrence of pathological SEPs was associated significantly more often with impairment of joint position and vibration sense, than with nonspecific sensory disturbances. Not only in some patients with first manifestation, but also in some patients with long, but mild courses, there were nonspecific sensory disturbances in association with normal SEPs. One should not underestimate the complaints in such cases.
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Córtex Cerebral/fisiopatologia , Potenciais Somatossensoriais Evocados , Nervo Mediano/fisiopatologia , Esclerose Múltipla/fisiopatologia , Sensação/fisiologia , Nervo Tibial/fisiopatologia , Adulto , Idoso , Estimulação Elétrica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
Cortical somatosensory evoked potentials following median and tibial nerve stimulation were compared with the findings in nuclear magnetic resonance imaging in 23 patients with multiple sclerosis, 11 of whom presented with their first disease manifestation. Pathological SEP's were found in 55 percent of patients presenting with first manifestation and in 83 percent of those with a longer duration of illness. Except for one patient with spinal cord involvement only, in whom no cerebral lesions were seen, all patients showed periventricular lesions in NMR. Between 1 and 16 (4.7 +/- 3.5) non-periventricular isolated lesions were found per patient. Cortical SEP's are affected differently by lesions within the thalamocortical system: Plaques within the internal capsule may result in SEP-changes as seen in other causes of damage to this region. However, lesions in this strategic area may also remain clinically and electrophysiologically silent. Nevertheless, the size of the lesion seen in NMR is not relevant, as observed in one case of an extensive plaque within the centrum semiovale. Correlations between the lesions near the parietal cortex or within the parietal white matter and SEP-component alterations of intermediate latency (N55, N75) remained insignificant.
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Córtex Cerebral/fisiopatologia , Encefalomielite/diagnóstico , Potenciais Somatossensoriais Evocados , Espectroscopia de Ressonância Magnética , Nervo Mediano/fisiopatologia , Tempo de Reação/fisiologia , Nervo Tibial/fisiopatologia , Adulto , Vias Aferentes/fisiopatologia , Doença Crônica , Estimulação Elétrica , Encefalomielite/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Núcleos Talâmicos/fisiopatologiaRESUMO
40 patients with a definite diagnosis and 16 patients with an initial manifestation of multiple sclerosis were investigated by cerebral nuclear magnetic resonance imaging (NMR) and compared. The initial manifestation is predominantly characterized in the NMR by significantly less periventricular involvement, especially within the region of the occipital horns, by significantly rarer appearance of confluent, periventricular lesions within the region of the pars centralis and the temporal horns of the lateral ventricles and by significantly rarer appearance of circumscribed non-periventricular lesions. Unlike those in definite multiple sclerosis, the morphology and distribution of the initial lesions do not show a stereotypical and diagnostically characteristic pattern. The importance of the cerebral NMR for the early diagnosis of multiple sclerosis lies primarily in the indication of disseminated lesions.
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Espectroscopia de Ressonância Magnética , Esclerose Múltipla/patologia , Adulto , Gânglios da Base/patologia , Tronco Encefálico/patologia , Cerebelo/patologia , Córtex Cerebral/patologia , Ventrículos Cerebrais/patologia , Feminino , Humanos , Hipotálamo/patologia , Masculino , Esclerose Múltipla/diagnóstico , Tálamo/patologiaRESUMO
The electroencephalograms of 40 patients with acute symptoms of multiple sclerosis, 10 of whom presented with primary manifestation, were compared with the findings in cerebral nuclear magnetic resonance imaging. 32.5% of the patients EEGs showed abnormalities. Considering borderline findings the percentage of remarkable EEGs mounted to 60%. All of the patients presented periventricular lesions in NMR. In addition to the periventricular abnormalities between 1 and 26 district lesions per patient were found (mean = 6.5; Median = 5). In the patients group with five and more non-periventricular lesions, there were significantly more pathologic EEG-findings (p less than 0.05) than in the group with fewer lesions. Statistical correlations between EEG-abnormalities and the extent of functional deficit could not be substantiated. Neither could type and locality of EEG-changes be correlated to non-periventricular lesions in NMR.
Assuntos
Eletroencefalografia , Espectroscopia de Ressonância Magnética , Esclerose Múltipla/diagnóstico , Adolescente , Adulto , Idoso , Nível de Alerta/fisiologia , Encéfalo/patologia , Encéfalo/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/patologia , Esclerose Múltipla/fisiopatologiaRESUMO
23 out of 24 patients with multiple sclerosis showed multiple, distinct lesions on investigation with cerebral nuclear magnetic resonance imaging (NMR). Arguments for the specific relationship of these lesions to demyelinating foci are: 1. Morphology and pattern of distribution agree to the known pathological observations. 2. Single lesions shown by computerized tomography (CT) were similarly located to lesions shown by NMR. The morphology and distribution of the lesions in the NMR show a common pattern largely independent of the individual neurological deficits. The nuclear magnetic resonance imaging is a method of high sensitivity and specificity for the diagnosis of multiple sclerosis. It offers valuable additional information in particular for early diagnosis and in cases of diagnostic uncertainty.
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Espectroscopia de Ressonância Magnética , Esclerose Múltipla/patologia , Adulto , Tronco Encefálico/patologia , Cerebelo/patologia , Córtex Cerebral/patologia , Ventrículos Cerebrais/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fibras Nervosas Mielinizadas/patologia , Vias Neurais/patologia , Nervo Óptico/patologia , Neurite Óptica/patologia , Medula Espinal/patologiaRESUMO
Extracranial aneurysms of the internal carotid artery are considered to be relatively rare. The main causes are constitutional vessel weakness arteriosclerosis and trauma. Neurological complications can sometimes give rise to confusing symptoms. Most important are transitory ischaemic attacks. Apart from these, damage by compression of the lower cranial and sympathetic nerves may occur. A case is reported in which the symptoms led to the topological diagnosis. The method of treatment used was that of delayed carotis ligature as described by van Dongen.
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Doenças das Artérias Carótidas/diagnóstico , Aneurisma Intracraniano/diagnóstico , Doenças das Artérias Carótidas/cirurgia , Artéria Carótida Interna/diagnóstico por imagem , Artéria Carótida Interna/cirurgia , Angiografia Cerebral , Doenças dos Nervos Cranianos/diagnóstico , Humanos , Aneurisma Intracraniano/cirurgia , Ataque Isquêmico Transitório/diagnóstico , Masculino , Pessoa de Meia-Idade , Síndromes de Compressão Nervosa/diagnósticoRESUMO
In course of a catamnesis during a period of 1,5 up to 5 years after operation we made electroencephalographic examinations in 140 patients submitted to an aorto-coronary-veins-bypass (ACVB). Compared with a control group of corresponding age we observed a significant frequency of focal disturbances, being interpreted as expression of an increased functional lability due to vascular effects. 14 percent of these patients showed evident signs of cerebrovascular insufficiency. 33 percent suffered from symptoms of the unspecific pseudoneurasthenic syndrome, often to be found in the preliminary region of cerebrovascular insufficiency. Compared with the control group we found among the EEG of alpha-type within the ACVB-group a significantly increased number of subvigilant patterns. There were no relations between the extent of these patterns and the clinical syndromes of cerebrovascular insufficiency and pseudoneurasthenia. The increased appearance of fluctuations of vigilance within the group showing a higher vascular morbidity can be regarded as a first step of limited regulative dynamics. The results of this study confirm the necessity of an interdisciplinary medical treatment of patients suffering from arteriosclerosis.
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Isquemia Encefálica/diagnóstico , Ponte de Artéria Coronária , Doença das Coronárias/cirurgia , Eletroencefalografia , Adulto , Idoso , Ritmo alfa , Nível de Alerta , Potenciais Evocados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neurastenia/diagnóstico , Complicações Pós-Operatórias/diagnósticoRESUMO
Relations between clozapine plasma levels and effects were investigated in 32 hospitalized patients. Clozapine dosage and plasma levels correlate linearly. The clinical improvement due to clozapine treatment was significant. A relationship between the rate of improvement and the plasma levels could be seen on the third day of treatment only. Of the side effects, body temperature elevation and orthostatic disregulation temporarily correlated with the plasma levels. Development of tolerance was seen with regard to the sedative effect and orthostatic disregulation. Linear correlations between pulse frequency as well as dopamine-beta-hydroxylase activity in serum and clinical improvement were observed during the second half of the 30-day treatment period.
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Clozapina/farmacologia , Dibenzazepinas/farmacologia , Temperatura Corporal/efeitos dos fármacos , Clozapina/efeitos adversos , Clozapina/sangue , Dopamina beta-Hidroxilase/sangue , Frequência Cardíaca/efeitos dos fármacos , HumanosRESUMO
The relationship between antipsychotic effect and side effects and plasma levels of clozapine were investigated in 26 patients. A significant linear correlation was found between dosage and plasma levels of clozapine. All patients were clearly improved. The degree of improvement was independent of the plasma levels in an average range of plasma levels (100 ng/ml-800 ng/ml). Sedation and orthostatic dysregulation occurred most pronounced on the third day of treatment. There was no relationship between plasma levels and these symptoms. After prolonged treatment the degree of both symptoms diminished. The development of tolerance of symptoms is concluded.