Estudo e projeto de um amplificador de áudio classe AB

Os amplificadores de áudio aplicados aos sistemas de alta potência necessitam de fidelidade e confiabilidade no seu funcionamento devido a operarem com altas tensões e altas correntes. Para a estabilização dos estágios de amplificação são utilizadas compensações que permitem a plena estabilidade do sistema quando o mesmo funciona em malha fechada, garantindo uma região de resposta em frequência com ganho estável entre a frequência de corte mínima e máxima. O presente trabalho objetivou o desenvolvimento de um circuito amplificador de áudio classe AB, considerado de alta potência, com 800 Wrms em uma carga de 4 ohms; ele utiliza as classes A e B com estabilizações que garantem a linearidade do sistema para amplificação dos sinais de tensão e corrente, que possibilitam uma banda passante estável de 20 Hz a 20 kHz. Para atingir os objetivos propostos neste trabalho, foi realizada a pesquisa e análise de circuitos elétricos já existentes para implementação em placa de circuito impresso, a fim de obter um resultado satisfatório, utilizando ferramentas de laboratório para aferimentos finais e as respectivas conclusões.The audio amplifiers applied to high-powered systems need fidelity and reliability in their functioning because they operate on a high voltage and high currents. For stabilization of the amplification stages, there are compensations that enable the full stability of the system when it functions on closed loop, ensuring a region of response in frequency with stable gain between the minimum and maximum cut-off flat response. The current study aimed to develop a class AB audio amplifier circuit, considered of high power, with 800 Wrms in a charge of 4 ohms; it utilizes the classes A and B as stabilizers that guarantee the linearity of the system for amplification of voltage and current signals that enable a stable pass band from 20 Hz to 20 kHz. Research and analysis of the existent electric circuits for implementation on printed circuit board were done to achieve the objectives proposed in this study, aimed to obtain a satisfactory result, utilizing laboratory tools for final benchmarking and respective conclusions

Immunogenicity of the Envelope Surface Unit of Human Endogenous Retrovirus K18 in Mice

The triggers for the development of multiple sclerosis (MS) have not been fully understood to date. One hypothesis proposes a viral etiology. Interestingly, viral proteins from human endogenous retroviruses (HERVs) may play a role in the pathogenesis of MS. Allelic variants of the HERV-K18 env gene represent a genetic risk factor for MS, and the envelope protein is considered to be an Epstein–Barr virus-trans-activated superantigen. To further specify a possible role for HERV-K18 in MS, the present study examined the immunogenicity of the purified surface unit (SU). HERV-K18(SU) induced envelope-specific plasma IgG in immunized mice and triggered proliferation of T cells isolated from these mice. It did not trigger phenotypic changes in a mouse model of experimental autoimmune encephalomyelitis. Further studies are needed to investigate the underlying mechanisms of HERV-K18 interaction with immune system regulators in more detail

Amyloid-Beta Peptides Trigger Aggregation of Alpha-Synuclein In Vitro

Alzheimer’s disease (AD) and Parkinson’s disease (PD), including dementia with Lewy bodies (DLB), account for the majority of dementia cases worldwide. Interestingly, a significant number of patients have clinical and neuropathological features of both AD and PD, i.e., the presence of amyloid deposits and Lewy bodies in the neocortex. The identification of α-synuclein peptides in amyloid plaques in DLB brain led to the hypothesis that both peptides mutually interact with each other to facilitate neurodegeneration. In this article, we report the influence of Aβ(1–42) and pGlu-Aβ(3–42) on the aggregation of α-synuclein in vitro. The aggregation of human recombinant α-synuclein was investigated using thioflavin-T fluorescence assay. Fibrils were investigated by means of antibody conjugated immunogold followed by transmission electron microscopy (TEM). Our data demonstrate a significantly increased aggregation propensity of α-synuclein in the presence of minor concentrations of Aβ(1–42) and pGlu-Aβ(3–42) for the first time, but without effect on toxicity on mouse primary neurons. The analysis of the composition of the fibrils by TEM combined with immunogold labeling of the peptides revealed an interaction of α-synuclein and Aβ in vitro, leading to an accelerated fibril formation. The analysis of kinetic data suggests that significantly enhanced nucleus formation accounts for this effect. Additionally, co-occurrence of α-synuclein and Aβ and pGlu-Aβ, respectively, under pathological conditions was confirmed in vivo by double immunofluorescent labelings in brains of aged transgenic mice with amyloid pathology. These observations imply a cross-talk of the amyloid peptides α-synuclein and Aβ species in neurodegeneration. Such effects might be responsible for the co-occurrence of Lewy bodies and plaques in many dementia cases

Expression, purification and initial characterization of human meprin β from Pichia pastoris

Human meprin β (h-meprin β), a single-zinc metalloendoprotease of the astacin family, is potentially involved in disorders such as fibrosis and Alzheimer’s disease. Here, we describe the expression of the enzyme in the yeast Pichia pastoris. The N-terminal signal sequence was replaced by the α-leader of Saccharomyces, enabling efficient secretion of the mature enzyme, harboring either an N-terminal or C-terminal His-tag. The purification by affinity and hydrophobic interaction chromatography resulted in isolation of 58.4 mg/l of homogenous human pro-meprin β from fermentation broth. The activated enzyme isolated from yeast (yh-meprin β) displayed virtually identical enzymatic activity as h-meprin from a mammalian cell line. Furthermore, the yh-meprin β was N-glycosylated and secreted as a dimer with a molecular mass of 148 kDa. Endoglycosidase H treatment generated a protein with a molecular mass of 133 kDa, but essentially unchanged kinetic parameters. Thus, our data suggest that human meprin β expressed in P. pastoris displays virtually identical parameters as meprin from other sources. The high yield of protein expression, the ease of purification and the deglycosylation in its native state appear to favor further studies aiming at inhibitor screening and structure-based inhibitor refinement

Digitalized and harmonized industrial production systems: the PERFoRM approach

On the one side, Industrial competitiveness today means shorter product lifecycles, increased product variety, and shorter times to market and customized tangible products and services. To face these challenges, the manufacturing industry is forced to move from traditional management, control, and automation approaches towards industrial cyber-physical systems. On the other side, several emergent engineering approaches and related Information-Communication-Control-Technologies, such as Multi-Agent-Systems, Service-Oriented Architecture, Plug-and-Produce Systems, Cloud and Fog Technologies, Big Data and Analytics, among others, have been researched during the last years. The confluence of those results with the latest developments in Industrial Digitalization, Systems-of-Cyber-Physical-Systems Engineering, Internet-of-Things, Internet-of-Services, and Industry 4.0 is opening a new broad spectrum of innovation possibilities. The PERFoRM (Production-harmonizEd-Reconfiguration of Flexible Robots and Machinery) approach is one of them. It teaches the reader what it means when production machines and systems are digitalized and migrated into Industrial Cyber-Physical Systems and what happens when they are networked and start collaborating with each other and with the human, using the internet. After a Technology Trend Screening and beyond a comprehensive state-of-the-art analysis about Industrial Digitalization and Industry 4.0-compliant solutions, the book introduces methods, architectures, and technologies applicable in real industrial use cases, explained for a broad audience of researchers, practitioners, and industrialistsinfo:eu-repo/semantics/publishedVersio

Continuous assays for meprin alpha and beta using prolyl tripeptidyl aminopeptidase (PtP) from Porphyromonas gingivalis

Common assays for endoprotease activity of meprin α and β are based on cleavage of internally quenched substrates. Although direct and convenient, for meprins these assays bear disadvantages such as, e.g., significant substrate inhibition or potential fluorescence quenching by compounds applied in inhibitor analysis. Here, wepresent a novel continuous assay by introducing an auxiliary enzyme, prolyl tripeptidyl aminopeptidase (PtP)and the chromogenic substrate KKGYVADAP- p-nitroanilide. We provide a quick strategy for expression and one-step-purification of the auxiliary enzyme. The enzyme kinetic data for meprin α and β suggest hyperbolic v/S-characteristics, the kinetic parameters of substrate conversion by meprin β were Km= 184 ± 32 μM and kcat=20 ± 4 s−1. We also present conditions for the use of the fluorogenic substrate KKGYVADAP-AMC to assess meprin β activity. The assays were applied for determination of inhibitory parameters of the naturalin hibitor actinonin and two recently published hydroxamates. Hence, we present two novel methods, which can be applied to assess inhibitory mechanism and potency with the attractive current drug targets meprin α and β.Furthermore, the assay might also provide implications for analysis of other endoproteases as well as their inhibitors

Immunogenicity of the Envelope Surface Unit of Human Endogenous Retrovirus K18 in Mice

The triggers for the development of multiple sclerosis (MS) have not been fully understood to date. One hypothesis proposes a viral etiology. Interestingly, viral proteins from human endogenous retroviruses (HERVs) may play a role in the pathogenesis of MS. Allelic variants of the HERV-K18 env gene represent a genetic risk factor for MS, and the envelope protein is considered to be an Epstein–Barr virus-trans-activated superantigen. To further specify a possible role for HERV-K18 in MS, the present study examined the immunogenicity of the purified surface unit (SU). HERV-K18(SU) induced envelope-specific plasma IgG in immunized mice and triggered proliferation of T cells isolated from these mice. It did not trigger phenotypic changes in a mouse model of experimental autoimmune encephalomyelitis. Further studies are needed to investigate the underlying mechanisms of HERV-K18 interaction with immune system regulators in more detail

Immunogenicity of the Envelope Surface Unit of Human Endogenous Retrovirus K18 in Mice

The triggers for the development of multiple sclerosis (MS) have not been fully understood to date. One hypothesis proposes a viral etiology. Interestingly, viral proteins from human endogenous retroviruses (HERVs) may play a role in the pathogenesis of MS. Allelic variants of the HERV-K18 env gene represent a genetic risk factor for MS, and the envelope protein is considered to be an Epstein–Barr virus-trans-activated superantigen. To further specify a possible role for HERV-K18 in MS, the present study examined the immunogenicity of the purified surface unit (SU). HERV-K18(SU) induced envelope-specific plasma IgG in immunized mice and triggered proliferation of T cells isolated from these mice. It did not trigger phenotypic changes in a mouse model of experimental autoimmune encephalomyelitis. Further studies are needed to investigate the underlying mechanisms of HERV-K18 interaction with immune system regulators in more detail

Immunogenicity of the Envelope Surface Unit of Human Endogenous Retrovirus K18 in Mice

The triggers for the development of multiple sclerosis (MS) have not been fully understood to date. One hypothesis proposes a viral etiology. Interestingly, viral proteins from human endogenous retroviruses (HERVs) may play a role in the pathogenesis of MS. Allelic variants of the HERV-K18 env gene represent a genetic risk factor for MS, and the envelope protein is considered to be an Epstein–Barr virus-trans-activated superantigen. To further specify a possible role for HERV-K18 in MS, the present study examined the immunogenicity of the purified surface unit (SU). HERV-K18(SU) induced envelope-specific plasma IgG in immunized mice and triggered proliferation of T cells isolated from these mice. It did not trigger phenotypic changes in a mouse model of experimental autoimmune encephalomyelitis. Further studies are needed to investigate the underlying mechanisms of HERV-K18 interaction with immune system regulators in more detail

Structure and Dynamics of Meprin β in Complex with a Hydroxamate-Based Inhibitor

The astacin protease Meprin β represents an emerging target for drug development due to its potential involvement in disorders such as acute and chronic kidney injury and fibrosis. Here, we elaborate on the structural basis of inhibition by a specific Meprin β inhibitor. Our analysis of the crystal structure suggests different binding modes of the inhibitor to the active site. This flexibility is caused, at least in part, by movement of the C-terminal region of the protease domain (CTD). The CTD movement narrows the active site cleft upon inhibitor binding. Compared with other astacin proteases, among these the highly homologous isoenzyme Meprin α, differences in the subsites account for the unique selectivity of the inhibitor. Although the inhibitor shows substantial flexibility in orientation within the active site, the structural data as well as binding analyses, including molecular dynamics simulations, support a contribution of electrostatic interactions, presumably by arginine residues, to binding and specificity. Collectively, the results presented here and previously support an induced fit and substantial movement of the CTD upon ligand binding and, possibly, during catalysis. To the best of our knowledge, we here present the first structure of a Meprin β holoenzyme containing a zinc ion and a specific inhibitor bound to the active site. The structural data will guide rational drug design and the discovery of highly potent Meprin inhibitors