493 resultados para Nef


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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T-cell based vaccine approaches have emerged to counteract HIV-1/AIDS. Broad, polyfunctional and cytotoxic CD4(+) T-cell responses have been associated with control of HIV-1 replication, which supports the inclusion of CD4(+) T-cell epitopes in vaccines. A successful HIV-1 vaccine should also be designed to overcome viral genetic diversity and be able to confer immunity in a high proportion of immunized individuals from a diverse HLA-bearing population. In this study, we rationally designed a multiepitopic DNA vaccine in order to elicit broad and cross-clade CD4(+) T-cell responses against highly conserved and promiscuous peptides from the HIV-1 M-group consensus sequence. We identified 27 conserved, multiple HLA-DR-binding peptides in the HIV-1 M-group consensus sequences of Gag, Pol, Nef, Vif, Vpr, Rev and Vpu using the TEPITOPE algorithm. The peptides bound in vitro to an average of 12 out of the 17 tested HLA-DR molecules and also to several molecules such as HLA-DP, -DQ and murine IA(b) and IA(d). Sixteen out of the 27 peptides were recognized by PBMC from patients infected with different HIV-1 variants and 72% of such patients recognized at least 1 peptide. Immunization with a DNA vaccine (HIVBr27) encoding the identified peptides elicited IFN-gamma secretion against 11 out of the 27 peptides in BALB/c mice; CD4(+) and CD8(+) T-cell proliferation was observed against 8 and 6 peptides, respectively. HIVBr27 immunization elicited cross-clade T-cell responses against several HIV-1 peptide variants. Polyfunctional CD4(+) and CD8(+) T cells, able to simultaneously proliferate and produce IFN-gamma and TNF-alpha, were also observed. This vaccine concept may cope with HIV-1 genetic diversity as well as provide increased population coverage, which are desirable features for an efficacious strategy against HIV-1/AIDS.

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Untersuchung zum Einfluss der ACD-CPR (Aktive Kompressions- Dekompressions-Reanimation) mit während der Dekompressionsphase blockiertem Gasfluss (Impedance-Threshold-Device) im Vergleich zur Standardreanimationsrechnik auf die Kurzzeit-Überlebensrate von Patienten mit präklinisch aufgetretenem Herzkreislaufstillstand. Die Studie vergleicht die ACD-ITD-CPR gegen die Standard-CPR bei Patienten mit präklinischem Herkreislaufstillstand. Primär untersuchter Parameter war die Ein-Stunden-Überlebensrate nach Krankenhausaufnahme. Sekundär wurden die Tastbarkeit eines Pulses unter CPR, die Wiederkehr des Spontankreislaufs (ROSC), die Rate an Krankenhausaufnahmen, 24-Stunden-Überleben und Krankenhausentlassungen untersucht. Außerdem wurde das neurologische Outcome evaluiert. Die Studie fand in Mainz statt; Mainz bietet sich für die Durchführung notfallmedizinischer Studien in besonderem Maße an. Der Rettungsdienst der Stadt arbeitet nach dem in Deutschland üblichen zweigliedrigen System mit RA/RS auf RTWs und NA auf NAW/NEF. Die Studie wurde nach einer fünfmonatigen Pilotphase und extensivem Training beider Verfahren durchgeführt. Zusätzlich bestanden bei einigen der Beteiligten schon Erfahrungen mit ACD-CPR. Es ergaben sich signifikante Vorteile der ACD-ITD-CPR gegenüber der Standard-CPR hinsichtlich des primär untersuchten Parameters (51% vs. 32% p=0,006), außerdem statistisch auffällige Vorteile hinsichtlich der Pulstastbarkeit unter CPR (85% vs. 69%, p=0,008), der Wiederkehr des Spontankreislaufs (55% vs. 37%, p=0,016), der Rate der Krankenhausaufnahmen (52% vs. 36%, p=0.023) und des 24-Stunden-Überlebens (37% vs. 22%, p=0,033). Es ergaben sich keine statistisch auffälligen Unterschiede hinsichtlich der Rate an Krankenhausentlassungen und im neurologischen Outcome. Die Ergebnisse lassen den Schluss zu, dass die ACD-ITD die Kurzzeitüberlebensrate der Patienten mit außerklinischem Herzkreislaufstillstand verbessern kann. Eine Voraussetzung hierfür ist eine ausreichende und andauernde Ausbildung der beteiligten Helfer und/oder die Verfügbarkeit technisch verbesserter Lösungen. Weitere Untersuchungen zum Einfluss auf die Langzeitüberlebensraten und das neurologische Outcome scheinen angezeigt.

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Peptides presented by MHC class I molecules for CTL recognition are derived mainly from cytosolic proteins. For antigen presentation on the cell surface, epitopes require correct processing by cytosolic and ER proteases, efficient TAP transport and MHC class I binding affinity. The efficiency of epitope generation depends not only on the epitope itself, but also on its flanking regions. In this project, the influence of the C-terminal region of the model epitope SIINFEKL (S8L) from chicken ovalbumin (aa 257-264) on antigen processing has been investigated. S8L is a well characterized epitope presented on the murine MHC class I molecule, H-2Kb. The Flp-In 293Kb cell line was transfected with different constructs each enabling the expression of the S8L sequence with different defined C-terminal flanking regions. The constructs differed at the two first C-terminal positions after the S8L epitope, so called P1’ and P2’. At these sites, all 20 amino acids were exchanged consecutively and tested for their influence on H-2Kb/S8L presentation on the cell surface of the Flp-In 293Kb cells. The detection of this complex was performed by immunostaining and flow cytometry. The prevailing assumption is that proteasomal cleavages are exclusively responsible for the generation of the final C-termini of CTL epitopes. Nevertheless, recent publications showed that TPPII (tripeptidyl peptidase II) is required for the generation of the correct C-terminus of the HLA-A3-restricted HIV epitope Nef(73-82). With this background, the dependence of the S8L generation on proteasomal cleavage of the designed constructs was characterized using proteasomal inhibitors. The results obtained indicate that it is crucial for proteasomal cleavage, which amino acid is flanking the C-terminus of an epitope. Furthermore, partially proteasome independent S8L generation from specific S8L-precursor peptides was observed. Hence, the possibility of other existing endo- or carboxy-peptidases in the cytosol that could be involved in the correct trimming of the C-terminus of antigenic peptides for MHC class I presentation was investigated, performing specific knockdowns and using inhibitors against the target peptidases. In parallel, a purification strategy to identify the novel peptidase was established. The purified peaks showing an endopeptidase activity were further analyzed by mass spectrometry and some potential peptidases (like e.g. Lon) were identified, which have to be further characterized.

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In Switzerland, approximately 350,000 people aged 70 years or older own a valid driving license. By law, these drivers are medically assessed every other year, most commonly by their general practitioner, to exclude that a medical condition is interfering with their driving skills. A prerequisite for driving is the integration of high-level cognitive functions with perception and motor function. Ageing, per se, does not necessarily impair driving or increase the crash risk. However, medical conditions, such as cognitive impairment and dementia, become more prevalent with advancing age and may contribute to poor driving and an increased crash risk. The extent to which driving skills are impaired depends on the cause of dementia, disease severity, other co-morbidities and individual compensation strategies. Dementia often remains undiagnosed and therefore general practitioners (GPs) can find themselves in the difficult situation to disclose a suspicion about cognitive impairment and queries about medical fitness to drive, at the same time. In addition, the literature suggests that cognitive screening tests, most commonly used by GPs, have a limited role in judging whether an older person remains fit to drive. Further specialist assessment, for example in a memory clinic or on the road testing (ORT), may be helpful when the diagnosis or its implication for driving remain unclear. Here, we review the literature about cognition and driving, for GPs who advise older drivers who wish to continue driving.

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In the past decade, several arm rehabilitation robots have been developed to assist neurological patients during therapy. Early devices were limited in their number of degrees of freedom and range of motion, whereas newer robots such as the ARMin robot can support the entire arm. Often, these devices are combined with virtual environments to integrate motivating game-like scenarios. Several studies have shown a positive effect of game-playing on therapy outcome by increasing motivation. In addition, we assume that practicing highly functional movements can further enhance therapy outcome by facilitating the transfer of motor abilities acquired in therapy to daily life. Therefore, we present a rehabilitation system that enables the training of activities of daily living (ADL) with the support of an assistive robot. Important ADL tasks have been identified and implemented in a virtual environment. A patient-cooperative control strategy with adaptable freedom in timing and space was developed to assist the patient during the task. The technical feasibility and usability of the system was evaluated with seven healthy subjects and three chronic stroke patients.

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We have developed a haptic-based approach for retraining of interjoint coordination following stroke called time-independent functional training (TIFT) and implemented this mode in the ARMin III robotic exoskeleton. The ARMin III robot was developed by Drs. Robert Riener and Tobias Nef at the Swiss Federal Institute of Technology Zurich (Eidgenossische Technische Hochschule Zurich, or ETH Zurich), in Zurich, Switzerland. In the TIFT mode, the robot maintains arm movements within the proper kinematic trajectory via haptic walls at each joint. These arm movements focus training of interjoint coordination with highly intuitive real-time feedback of performance; arm movements advance within the trajectory only if their movement coordination is correct. In initial testing, 37 nondisabled subjects received a single session of learning of a complex pattern. Subjects were randomized to TIFT or visual demonstration or moved along with the robot as it moved though the pattern (time-dependent [TD] training). We examined visual demonstration to separate the effects of action observation on motor learning from the effects of the two haptic guidance methods. During these training trials, TIFT subjects reduced error and interaction forces between the robot and arm, while TD subject performance did not change. All groups showed significant learning of the trajectory during unassisted recall trials, but we observed no difference in learning between groups, possibly because this learning task is dominated by vision. Further testing in stroke populations is warranted.

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A new overground body-weight support system called ZeroG has been developed that allows patients with severe gait impairments to practice gait and balance activities in a safe, controlled manner. The unloading system is capable of providing up to 300 lb of static support and 150 lb of dynamic (or constant force) support using a custom-series elastic actuator. The unloading system is mounted to a driven trolley, which rides along an overhead rail. We evaluated the performance of ZeroG's unloading system, as well as the trolley tracking system, using benchtop and human-subject testing. Average root-mean-square and peak errors in unloading were 2.2 and 7.2 percent, respectively, over the range of forces tested while trolley tracking errors were less than 3 degrees, indicating the system was able to maintain its position above the subject. We believe training with ZeroG will allow patients to practice activities that are critical to achieving functional independence at home and in the community.

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Memory Clinics provide evidence based diagnosis and treatment of dementia. Whenever a diagnosis of dementia is made, it is important to inform the patients about the possible impact of dementia on driving. Patients and their next of kin require competent advice whenever this difficult question is addressed and the mobility desire and the risks related to driving need to be carefully weight up. The time of diagnosis does not necessarily equate to the time when a person with dementia becomes an unsafe driver. The cause and severity of dementia, comorbidities and the current medication need to be carefully taken into account for this decision. On behalf of the association of the Swiss Memory Clinics, a group of experts has developed recommendations to assess fitness to drive in cognitively impaired older adults.