167 research outputs found
Electromagnetic hybrid active-passive vehicle suspension system
The suspension systems currently in use can be classified as passive, semi-active and active. The passive suspension systems are the most commonly used due to their low price and high reliability. However, this system can not assure the desired performance from a modem suspension system An important improvement of the suspension performance is achieved by the active systems. Nevertheless, they are only used in a very reduced number of automobile models because they are expensive and complex. Another disadvantage of active systems is the relatively high energy consumption. The use of electromagnetic linear actuators is an alternative for the implementation of active suspensions. Moreover, this solution has the advantage of the suspension energy recovery. In spite of the materials development, the electromagnetic actuators are yet expensive to produce. In this paper it is proposed an hybrid suspension system which combines the simplicity of the passive dampers with the performance of an electromagnetic active suspension. Maintaining the passive damper, it is possible to keep the performance of the active suspension, but using a smaller electromagnetic actuator
Antiviral Potential of Algal Metabolites—A Comprehensive Review
Historically, algae have stimulated significant economic interest particularly as a source of fertilizers, feeds, foods and pharmaceutical precursors. However, there is increasing interest in exploiting algal diversity for their antiviral potential. Here, we present an overview of 50-years of scientific and technological developments in the field of algae antivirals. After bibliometric analysis of 999 scientific references, a survey of 16 clinical trials and analysis of 84 patents, it was possible to identify the dominant algae, molecules and viruses that have been shaping and driving this
promising field of research. A description of the most promising discoveries is presented according to
molecule class. We observed a diverse range of algae and respective molecules displaying significant
antiviral effects against an equally diverse range of viruses. Some natural algae molecules, like
carrageenan, cyanovirin or griffithsin, are now considered prime reference molecules for their outstanding antiviral capacity. Crucially, while many algae antiviral applications have already reached
successful commercialization, the large spectrum of algae antiviral capacities already identified suggests a strong potential for future expansion of this field
Doença Hepática Crónica Agudizada: Revisão da Experiência de um Centro Português de Referenciação
Acute-on-chronic liver failure (ACLF) is a syndrome characterized by an acute deterioration of a patient with cirrhosis, frequently associated with multi-organ failure and a high short-term mortality rate. We present a retrospective study that aims to characterize the presentation, evolution, and outcome of patients diagnosed with ACLF at our center over the last 3 years, with a comparative analysis between the group of patients that had ACLF precipitated by infectious insults of bacterial origin and the group of those with ACLF triggered by a nonbacterial infectious insult; the incidence of acute kidney injury and its impact on the prognosis of ACLF was also analyzed. Twenty-nine patients were enrolled, the majority of them being male (89.6%), and the mean age was 53 years. Fourteen patients (48.3%) developed ACLF due to a bacterial infectious event, and 9 of them died (64.2%, overall mortality rate 31%); however, no statistical significance was found (p < 0.7). Of the remaining 15 patients (51.7%) with noninfectious triggers, 11 died (73.3%, overall mortality rate 37.9%); again there was no statistical significance (p < 0.7). Twenty-four patients (83%) developed acute kidney injury (overall mortality rate 65.5%; p < 0.022) at the 28-day and 90-day follow-up. Twelve patients had acute kidney injury requiring renal replacement therapy (41.37%; overall mortality rate 37.9%; p < 0.043). Hepatic transplant was performed in 3 patients, with a 100% survival at the 28-day and 90-day follow-up (p < 0.023). Higher grades of ACLF were associated with increased mortality (p < 0.02; overall mortality 69%).
CONCLUSIONS:
ACLF is a heterogeneous syndrome with a variety of precipitant factors and different grades of extrahepatic involvement. Most cases will have some degree of renal dysfunction, with an increased risk of mortality. Hepatic transplant is an efficient form of therapy for this syndrome.info:eu-repo/semantics/publishedVersio
Implementação em Portugal de um estudo de prevalência da demência e da depressão geriátrica: a metodologia do 10/66 Dementia Research Group
ResumoIntroduçãoA demência e a depressão têm um impacto social muito significativo. Em Portugal, escasseiam dados epidemiológicos em pessoas idosas na comunidade. Em países em desenvolvimento, o 10/66 Dementia Research Group (DRG) conduziu múltiplos estudos sobre a prevalência e a incidência destes quadros. Os protocolos de avaliação 10/66‐DRG foram validados extensivamente nesses países, havendo vantagens potenciais na aplicação em regiões europeias com populações idosas de baixa escolaridade. Neste estudo, fundamentamos e descrevemos a implementação em Portugal da metodologia 10/66‐DRG para estudo da prevalência da demência e da depressão geriátrica.Materiais e métodosO trabalho de campo desenrola‐se numa fase única, em áreas geográficas definidas, sendo avaliados detalhadamente e de forma sistemática todos os residentes de 65 anos ou mais. A informação é recolhida dos participantes e de informadores próximos (www.alz.co.uk/1066/).ResultadosSelecionámos e mapeámos uma área urbana (em Fernão Ferro) e outra rural (em Mora), definindo amostras finais de 702 e 779 pessoas, respetivamente. Os instrumentos de avaliação foram cuidadosamente traduzidos e adaptados ao contexto português. Teve lugar um treino rigoroso dos entrevistadores, assegurando a fiabilidade de cotação interobservadores.Discussão e conclusãoA aplicação dos protocolos 10/66‐DRG permitirá obter dados robustos de prevalência de demência e de depressão, com amostras comunitárias de pessoas idosas em Portugal. Dada a validade internacional da metodologia utilizada, estes resultados serão comparáveis com os de outros centros 10/66, à escala mundial.AbstractIntroductionDementia and depression have a huge social impact. In Portugal, epidemiological data is scarce regarding community dwelling elderly people with these conditions. In developing countries, the 10/66 Dementia Research Group‐DRG has conducted multiple studies on the corresponding prevalence and incidence. The 10/66‐DRG protocols for population‐based studies were extensively validated in those countries, and there is a rationale to apply them in low literacy elderly populations in Europe. We describe the implementation of the protocols related to the prevalence study (on dementia and geriatric depression) in Portuguese settings.Materials and methodsThis is a one‐phase survey, in which all people 65+ years living in defined catchment areas are comprehensively evaluated. Information is collected directly from participants and from a related informant (www.alz.co.uk/1066/).ResultsWe selected and mapped an urban area (in Fernão Ferro) and a rural one (in Mora). The final samples were n=702 and n=779 respectively. Questionnaires were carefully translated and culturally adapted. Rigorous training procedures took place to ensure inter‐rater reliability.Discussion and conclusionsThe implementation of the 10/66‐DRG protocols will lead to robust data on the prevalence of dementia and depression in community samples of elderly people in Portugal. Given the international validity of our methodology, these results will be comparable with those from other 10/66 centres around the world
A European Academy of Neurology guideline on medical management issues in dementia
BACKGROUND AND PURPOSE: Dementia is one of the most common disorders and is associated with increased morbidity, mortality and decreased quality of life. The present guideline addresses important medical management issues including systematic medical follow‐up, vascular risk factors in dementia, pain in dementia, use of antipsychotics in dementia and epilepsy in dementia. METHODS: A systematic review of the literature was carried out. Based on the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) framework, we developed a guideline. Where recommendations based on GRADE were not possible, a good practice statement was formulated. RESULTS: Systematic management of vascular risk factors should be performed in patients with mild to moderate dementia as prevention of cerebrovascular pathology may impact on the progression of dementia (Good Practice statement). Individuals with dementia (without previous stroke) and atrial fibrillation should be treated with anticoagulants (weak recommendation). Discontinuation of opioids should be considered in certain individuals with dementia (e.g. for whom there are no signs or symptoms of pain or no clear indication, or suspicion of side effects; Good Practice statement). Behavioral symptoms in persons with dementia should not be treated with mild analgesics (weak recommendation). In all patients with dementia treated with opioids, assessment of the individual risk–benefit ratio should be performed at regular intervals. Regular, preplanned medical follow‐up should be offered to all patients with dementia. The setting will depend on the organization of local health services and should, as a minimum, include general practitioners with easy access to dementia specialists (Good Practice statement). Individuals with dementia and agitation and/or aggression should be treated with atypical antipsychotics only after all non‐pharmacological measures have been proven to be without benefit or in the case of severe self‐harm or harm to others (weak recommendation). Antipsychotics should be discontinued after cessation of behavioral disturbances and in patients in whom there are side effects (Good Practice statement). For treatment of epilepsy in individuals with dementia, newer anticonvulsants should be considered as first‐line therapy (Good Practice statement). CONCLUSION: This GRADE‐based guideline offers recommendations on several important medical issues in patients with dementia, and thus adds important guidance for clinicians. For some issues, very little or no evidence was identified, highlighting the importance of further studies within these areas
White Matter Lesion Progression in LADIS Frequency, Clinical Effects, and Sample Size Calculations
BACKGROUND AND PURPOSE:
White matter lesion (WML) progression has been advocated as a surrogate marker in intervention trials on cerebral small vessel disease. We assessed the rate of visually rated WML progression, studied correlations between lesion progression and cognition, and estimated sample sizes for clinical trials with pure WML progression vs combined WML progression-cognitive outcomes.
METHODS:
Those 394 participants of the Leukoaraiosis and Disability Study (LADIS) study with magnetic resonance imaging scanning at baseline and 3-year follow-up were analyzed. WML progression rating relied on the modified Rotterdam Progression Scale. The Vascular Dementia Assessment Scale global score and a composite score of specific executive function tests assessed longitudinal change in cognition. Sample size calculations were based on the assumption that treatment reduces WML progression by 1 grade on the Rotterdam Progression Scale.
RESULTS:
WML progression related to deterioration in cognitive functioning. This relationship was less pronounced in subjects with early confluent and confluent lesions. Consequently, studies in which the outcome is cognitive change resulting from treatment effects on lesion progression will need between 1809 subjects per treatment arm when using executive tests and up to 18 853 subjects when using the Vascular Dementia Assessment Scale score. Studies having WML progression as the sole outcome will need only 58 or 70 individuals per treatment arm.
CONCLUSIONS:
WML progression is an interesting outcome for proof-of-concept studies in cerebral small vessel disease. If cognitive outcome measures are added to protocols, then sample size estimates increase substantially. Our data support the use of an executive test battery rather than the Vascular Dementia Assessment Scale as the primary cognitive outcome measure
Confirmatory factor analysis of the Neuropsychological Assessment Battery of the LADIS study: a longitudinal analysis
WOS:000315985900004Age-related white matter changes have been associated with cognitive functioning, even though their role is not fully understood. This work aimed to test a 3-factor model of the neuropsychological assessment battery and evaluate how the model fit the data longitudinally. Confirmatory factor analysis (CFA) was used to investigate the dimensions of a structured set of neuropsychological tests administered to a multicenter, international sample of independent older adults (LADIS study). Six hundred and thirty-eight older adults completed baseline neuropsychological, clinical, functional and motor assessments, which were repeated each year for a 3-year follow-up. CFA provided support for a 3-factor model. These factors involve the dimensions of executive functions, memory functions, and speed and motor control abilities. Performance decreased in most neuropsychological measures. Results showed that executive functioning, memory and speed of motor abilities are valid latent variables of neuropsychological performance among older adults, and that this structure is relatively consistent longitudinally, even though performance decreases with time.info:eu-repo/semantics/acceptedVersio
Diffusion-Weighted Imaging and Cognition in the Leukoariosis and Disability in the Elderly Study
BACKGROUND AND PURPOSE-: The mechanisms by which leukoariosis impacts on clinical and cognitive functions are not yet fully understood. We hypothesized that ultrastructural abnormalities of the normal-appearing brain tissue (NABT) assessed by diffusion-weighted imaging played a major and independent role. METHODS-: In addition to a comprehensive clinical, neuropsychologic, and imaging work-up, diffusion-weighted imaging was performed in 340 participants of the multicenter leukoariosis and disability study examining the impact of white matter hyperintensities (WMH) on 65-to 85-year old individuals without previous disability. WMH severity was rated according to the Fazekas score. Multivariate regression analysis served to assess correlations of histogram metrics of the apparent diffusion coefficient (ADC) of whole-brain tissue, NABT, and of the mean ADC of WMH with cognitive functions. RESULTS-: Increasing WMH scores were associated with a higher frequency of hypertension, a greater WMH volume, more brain atrophy, worse overall cognitive performance, and changes in ADC. We found strong associations between the peak height of the ADC histogram of whole-brain tissue and NABT with memory performance, executive dysfunction, and speed, which remained after adjustment for WMH lesion volume and brain atrophy and were consistent among centers. No such association was seen with the mean ADC of WMH. CONCLUSIONS-: Ultrastructural abnormalities of NABT increase with WMH severity and have a strong and independent effect on cognitive functions, whereas diffusion-weighted imaging metrics within WMH have no direct impact. This should be considered when defining outcome measures for trials that attempt to ameliorate the consequences of WMH progression
Small vessel disease and general cognitive function in nondisabled elderly : The LADIS study
Background and Purpose - On cerebral magnetic resonance imaging (MRI), white matter hyperintensities (WMH) and lacunes are generally viewed as evidence of small vessel disease. The clinical significance of small vessel disease in terms of global cognitive function has as yet not been completely clarified. We investigated the independent contribution of WMH and lacunes to general cognitive function in a group of independently living elderly with varying degrees of small vessel disease. Methods - Data were drawn from the multicenter, multinational Leukokraurosis and Disability (LADIS) study. There were 633 independently living participants. General cognitive function was assessed using the Mini Mental State Examination (MMSE) and the modified Alzheimer Disease Assessment Scale (ADAS). On MRI, WMH was rated as mild, moderate, or severe. Lacunes were rated as none, few (1 to 3), or many (4 or more). Results - In the basic analysis, increasing severity of both WMH and lacunes was related to deteriorating score on the MMSE and ADAS. When WMH and lacunes were entered simultaneously, both MRI measures remained significantly associated with MMSE score. Increasing severity of WMH remained associated with ADAS score, whereas the association with lacunes became less prominent. These associations were independent of other risk factors for dementia, like education, depression, vascular risk factors, or stroke. Conclusion - We found WMH and lacunes to be independently associated with general cognitive function in a sample of independently living elderly. These results highlight the fact that WMH and lacunes should both be evaluated when assessing small vessel disease in relation to cognitive function
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