2,469 research outputs found

    Involvement of lysine-88 of spinach ferredoxin-NADP+ reductase in the interaction with ferredoxin

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    AbstractA mutant of spinach ferredoxin-NADP+ reductase, in which Lys-88 has been changed to glutamine, has been obtained by site-directed mutagenesis. The mutant enzyme was fully active as a diaphorase, but partially impaired in ferredoxin-dependent cytochrome c reductase activity. By steady-state kinetics, the Km for ferredoxin of the K88Q enzyme was found to have increased 10-fold, whereas the kcat was unaffected by the amino acid replacement. The interaction between oxidized ferredoxin and the enzyme forms was also studied by spectrofluorimetric titration:Kd values of 110 and 10 nM were determined for the mutant and wild-type proteins, respectively. These data point out the importance of a positive charge at position 88 of the reductase for the interaction with ferredoxin, confirming previous cross-linking studies

    Role of the C. elegans U2 snRNP protein MOG-2 in sex determination, meiosis, and splice site selection

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    In Caenorhabditis elegans, germ cells develop as spermatids in the larva and as oocytes in the adult. Such fundamentally different gametes are produced through a fine-tuned balance between feminizing and masculinizing genes. For example, the switch to oogenesis requires repression of the fem-3 mRNA through the mog genes. Here we report on the cloning and characterization of the sex determination gene mog-2. MOG-2 is the worm homolog of spliceosomal protein U2A′. We found that MOG-2 is expressed in most nuclei of somatic and germ cells. In addition to its role in sex determination, mog-2 is required for meiosis. Moreover, MOG-2 binds to U2B″/RNP-3 in the absence of RNA. We also show that MOG-2 associates with the U2 snRNA in the absence of RNP-3. Therefore, we propose that MOG-2 is a bona fide component of the U2 snRNP. Albeit not being required for general pre-mRNA splicing, MOG-2 increases the splicing efficiency to a cryptic splice site that is located at the 5′ end of the exon

    Is avian influenza virus A(H5N1) a real threat to human health?

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    The A(H5N1) influenza remains a disease of birds with a significant species barrier: in the presence of some tens million cases of infection in poultry - with a wide geographical spread -, only a few hundreds cases have occurred in humans. To date, human cases have been reported in 15 countries - mainly in Asia - and all were related to the onset of outbreaks in poultry. A peak of H5N1 human cases was recorded in 2006, then decreasing in subsequent years. Despite this trend, the H5N1 virus still represents a possible threat to human health, considering that more than half of human cases of H5N1 have been fatal. Moreover, despite the drop in the number of cases, the risk of a novel pandemic cannot be excluded, since H5N1 continues to circulate in poultry in countries with elevated human population density and where monitoring systems are not fully appropriate. In addition, there is a major global concern about the potential occurrence of a reassortment between the 2009 pandemic H1N1 and the highly pathogenic H5N1 influenza viruses following a co-infection in a susceptible host. Therefore, the implementation of appropriate surveillance and containment measures is crucial in order to minimize such risk. In conclusion, H5N1 avian influenza is still a rare disease in humans but its clinical severe outcome requires a careful monitoring of the virus?s ability to evolve and to trigger a new pandemic

    The Focus-activity Framework for Evaluating PSS Cooperation Readiness of Manufacturing Firms

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    For manufacturing companies venturing the first steps on the Servitization roadmap, it may be difficult to imagine how an integrated approach of Product and Service elements could support the strategic goals efficiently. If Service tasks, roles, units and organizational structure are still developing and emerging from the Product business activities, the design of Product-Service cooperation as well is promising, as the way is unclear. For these companies, it seems to be important to understand their current status of Product-Service cooperation at first, before starting to design integration activities. Therefore, this paper presents a framework which is designed to help companies identify their current status – and strategic objectives later on – at two dimensions: a) the Structural Focus of Product and Service business within the company, and b) the Cooperation Activities which are undertaken by Product and Service representatives. By the means of a case study in the Italian luxury textile sector, a first validation of the model is conducted, assessing the static and dynamic characteristics of Product and Service business with involvement of an Italian textile company

    An engineering vector-like approach to attitude kinematics & nominal attitude state tracking control

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    In dealing with rigid body three-dimensional rotational motion, one is inevitably led to face the fact that rotations are not vector quantities. They may, however, be treated as such when the angle of rotation is (very) small. In this context, i.e. the infinitesimal case analysis, the time derivatives of the rotation variables hold simple (sometimes vector-like) relationships to the components of the angular velocity vector. Conventionally, this distinctive characteristic cannot be associated with general moderate-to-large rotations. In this thesis, it is demonstrated that the kinematical differential relationship between the rotation vector and the angular velocity vector may, in fact, be expressed in terms of a mere time derivative, provided that the angle of rotation is kept within moderate bounds. The key to achieve such simplicity in the kinematical equation (linear attitude kinematics) within moderate angles of rotation is a judicious choice of the basis from which the time derivative is observed. This result is used to advantage within a generalised version of Euler’s motion equations to construct a simple control law, which nominally realises both linear attitude tracking and linear angular velocity tracking (nominal linear attitude state tracking), within moderate attitude tracking errors. The analytical work presented here is unique in the sense that it combines attitude kinematics, dynamics and control in such a way that nominal linearity between the attitude state error variables is achieved within moderate attitude tracking errors. For the first time, an attitude control law explicitly enables the nominal closed-loop attitude state error dynamics to be chosen and motivated by useful physical concepts from linear control theory. The text also includes numerical simulations that validate and illustrate the theoretically achieved results.CAPES, Fundação Casimiro Montenegro FilhoNo tratamento do movimento rotacional tridimensional de corpos rígidos é inevitável lidar-se com o fato de que rotações não são quantidades vetoriais. Elas podem, no entanto, ser tratadas como tais quando o ângulo de rotação é (muito) pequeno. Neste contexto, ou seja, o da análise infinitesimal, as derivadas temporais das variáveis de rotação mantêm um relacionamento simples (às vezes mesmo do tipo vetorial) com os componentes do vetor velocidade angular. Convencionalmente, esta distinta característica não pode ser associada a rotações grandes, nem mesmo medianas. Nesta tese é demonstrado que a relação diferencial entre o vetor rotação e o vetor velocidade angular pode, na realidade, ser expressa em termos de uma simples derivada temporal, desde que o ângulo de rotação seja mantido numa faixa moderada. O artifício permitindo tal simplicidade na equação cinemática (cinemática linear de atitude) com um ângulo de rotação moderado é a escolha criteriosa da base a partir da qual a derivada temporal é observada. Este resultado é utilizado vantajosamente em conjunto com uma versão generalizada das equações de movimento de Euler na construção de uma lei de controle simples. Essa lei realiza, concomitantemente, o rastreamento linear nominal de atitude e o rastreamento linear nominal de velocidade angular (rastreamento linear nominal de estado rotacional), dentro de uma faixa moderada de erro de rastreamento de atitude. O trabalho analítico apresentado é único no sentido em que este combina cinemática rotacional, dinâmica rotacional e controle de forma tal que linearidade nominal entre as variáveis de erro de estado é atingida mesmo para erros moderados de rastreamento de atitude. Pela primeira vez, uma lei de controle permite explicitamente que a dinâmica de erro de estado rotacional em malha fechada seja escolhida e motivada por conceitos físicos úteis da teoria linear de controle. O texto também inclui simulações numéricas que validam e ilustram os resultados teóricos obtidos

    Molecular cloning and chemical synthesis of a novel antibacterial peptide derived from pig myeloid cells

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    A group of myeloid precursors of defense peptides has recently been shown to have highly homologous N-terminal regions. Using a strategy based on this homology, a novel cDNA was cloned from pig bone marrow RNA and found to encode a 153-residue polypeptide. This comprises a highly conserved region encompassing a 29-residue signal peptide and a 101-residue prosequence, followed by a unique, 23-residue, cationic, C-terminal sequence. A peptide corresponding to this C-terminal sequence was chemically synthesized and shown to exert antimicrobial activity against both Gram positive and negative bacteria at concentrations of 2-16 microM. The activity of this potent and structurally novel antibacterial peptide appears to be mediated by its ability to damage bacterial membranes, as shown by the rapid permeabilization of the inner membrane of Escherichia coli

    Clinical, epidemiological and virological features of acute hepatitis B in Italy

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    Purpose To evaluate the association of hepatitis B virus (HBV) genotypes, basal core promoter (BCP)/precore (PC) and S gene mutations with the clinical-epidemiological characteristics of acute hepatitis B (AHB) in Italy. Methods During July 2005–January 2007, 103 symptomatic AHB patients were enrolled and prospectively followed up at 15 national hospitals. HBV genotypes, BCP/ PC and S gene variants were determined by nested-PCR and direct sequence analysis. Results Genotype D, A and F were detected in 49, 45 and 6 % of patients, respectively. BCP, PC, and BCP plus PC variants were found in 3.1, 11.3 and 7.2 % of patients, respectively. At enrollment, 68.3 % of patients were hepatitis B e antigen (HBeAg)-positive and 31.7 % HBeAg-negative. BCP/PC mutations were more common in HBeAg-negative than in HBeAg-positive patients (p < 0.0001). Compared to genotype D patients, those harboring non-D genotypes were more frequently males (p = 0.023), HBeAg-positive (p < 0.001), had higher bilirubin (p = 0.014) and viremia (p = 0.034) levels and less frequently carried BCP/PC mutations (p < 0.001). Non-D genotype patients more often were from Central Italy (p = 0.001) and reported risky sexual exposure (p = 0.021). Two patients had received vaccination before AHB: one harbored genotype F; the other showed a S gene mutation. Four patients developed fulminant AHB; mutations were found in 2 of 3 patients who underwent BCP/ PC sequencing. After a 6-month follow-up, only 2 (2.8 %) patients developed persistent infection. Conclusion AHB by non-D genotypes is increasing in Italy and is associated with risky sexual exposure. The ability of some genotypes to cause persistent and/or severe infection in Italy warrants larger studies for clarificatio

    Six Years of Experience in Treating Facial Trauma in the Province of Brescia, Italy

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    Facial trauma is an enormous public health problem with overwhelmingly negative physical and psychological impacts. The authors retrospectively analyzed the incidence, etiology, clinical presentations, and characteristics of facial fractures along with sociodemographic, economic, and cultural factors. They analyzed facial fractures treated from June 2010 to December 2016 at the operative unit. Maxillofacial Adult Surgery Unit, Spedali Civili Brescia, Italy, with particular attention to the associations among age, etiology, fracture site, and clinical management
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