970 resultados para Class D audio amplifier
Resumo:
Data on short and long term efficacy and safety of d,l sotalol in patients with atrial fibrillation or atrial flutter is limited. The aims of this study were to (1) assess the antiarrhythmic efficacy of d,l sotalol maintaining normal sinus rhythm in patients with refractory atrial fibrillation or flutter, (2) evaluate the efficacy of d,l sotalol in preventing recurrences of paroxysmal atrial fibrillation or flutter, (3) evaluate the control of ventricular rate in patients with paroxysmal or refractory atrial fibrillation or flutter unsuccessfully treated with other antiarrhythmic agents, (4) determine predictors of efficacy (5) assess the safety of d,l sotalol in this setting. Two hundred patients with chronic or paroxysmal atrial fibrillation or atrial flutter or both, who had failed one to six previous antiarrhythmic drug trials were treated with d,l sotalol 80 to 440 mg/day orally. Fifty four percent was female, age 47 +/- 16 years (range 7-79), follow up period 7 +/- 7 months (range 1 to 14 months), 79% of patients had the arrhythmia for more than one year. The atrial fibrillation in 37.5% of patients was chronic and paroxysmal in 23.5. The atrial flutter was chronic in 31% of patients and paroxysmal in 8%. Eighty two percent of patients was in functional class I (NYHA) and 82% had cardiac heart disease: left atrial (LA) size 44 +/- 10 mm, right atrial (RA) size 37 +/- 7 mm and left ventricular ejection fraction (LVEF) 58 +/- 8%. Total success was achieved in 58% of patients (atrial fibrillation 40% and 18% in atrial flutter), partial success in 38% (atrial fibrillation in 18% and 20% in atrial flutter) and 4% of patients failure. It was p < 0.07 when compared total success vs partial success among atrial fibrillation and atrial flutter groups. Patients with cardiac heart disease responded worst (p = 0.10) to the drug than those without it, specially if the heart was dilated. We concluded that d,l sotalol has moderate efficacy to convert and maintain normal sinus rhythm, as well as it acts controlling paroxysmal relapses and ventricular heart rate.
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Class I major histocompatibility complex (MHC) molecules induce either accelerated rejection or prolonged survival of allografts, presumably because of the presence of immunogenic or tolerogenic epitopes, respectively. To explore the molecular basis of this phenomenon, three chimeric class I molecules were constructed by substituting the rat class I RT1.A$\sp{\rm a}$ sequences with the N-terminus of HLA-A2.1 (N$\sp{\rm HLA-A2.1}$-RT1.A$\sp{\rm a}$), the $\alpha\sb1$ helix (h) with $\rm\alpha\sb{1h}\sp{u}$ sequences ( ($\rm\alpha\sb{1h}\sp{u}$) -RT1.A$\sp{\rm a}$) or the entire $\alpha\sb2$ domain (d) with $\rm\alpha\sb{2d}\sp{u}$ sequences ( ($\rm\alpha\sb{2d}\sp{u}$) -RT1.A$\sp{\rm a}$). Wild type (WT) and chimeric cDNAs were sequenced prior to transfection into Buffalo (BUF; RT1$\sp{\rm b}$) hepatoma cells. Stable transfectants were injected subcutaneously (s.c.) into different hosts 7 days prior to challenge with a heart allograft. In BUF hosts, chimeric ($\rm\alpha\sb{1h}\sp{u}$) -RT1.A$\sp{\rm a}$ accelerated the rejection of Wistar Furth (WF; RT1$\sp{\rm u}$) heart allografts, but had no effect on the survival of ACI (RT1$\sp{\rm a}$) grafts. In contrast, the ($\rm\alpha\sb{2d}\sp{u}$) -RT1.A$\sp{\rm a}$ (containing $\rm\alpha\sb{1d}\sp{a}$ sequences) immunized BUF recipients toward RT1$\sp{\rm a}$ grafts. In WF hosts, WT-RT1.A$\sp{\rm a}$ was a potent immunogen and accelerated ACI graft rejection, N$\sp{\rm HLA-A2.1}$-RT1.A$\sp{\rm a}$ was less effective and ($\rm\alpha\sb{\rm 1h}\sp{u}\rbrack$-RT1.A$\sp{\rm a}$ was not immunogenic. Thus, dominant and subdominant epitopes inducing in vivo sensitization to cardiac allografts are present in the $\alpha\sb1$ helix and the N-terminus, respectively. The failure of ($\rm\alpha\sb{2d}\sp{u}$) -RT1.A$\sp{\rm a}$ transfectants (containing recipient-type $\alpha\sb{\rm 2d}$ sequences) to sensitize WF hosts toward ACI (RT1$\sp{\rm a}$) grafts, despite the presence of donor-type immunogenic $\alpha\sb{\rm 1d}\sp{\rm a}$, suggests that "self-$\alpha\sb2$" sequences displayed on chimeric antigens interfere with immunogenicity. The ($\rm\alpha\sb{1h}\sp{u}$) -RT1.A$\sp{\rm a}$ transfectants injected s.c. prolonged the survival of WF (RT1$\sp{\rm u}$) hearts in ACI (RT1$\sp{\rm a}$) recipients. Furthermore, intra-portal injection of extracts from ($\rm\alpha\sb{1h}\sp{u}$) -RT1.A$\sp{\rm a}$, but not WT-RT1.A$\sp{\rm a}$ or RT1.A$\sp{\rm u}$, in conjunction with a brief cyclosporine course rendered ACI hosts permanently and specifically tolerant to donor-type WF cardiac allografts. Thus, immunodominant allodeterminants are present in the $\alpha\sb1$, but not the $\alpha\sb2$, domain of rat class I MHC molecules. Furthermore, the $\rm\alpha\sb{1h}\sp{u}$ immunogenic epitopes trigger tolerogenic responses when flanked by host-type N-terminal$\sp{\rm a}$ and $\rm\alpha\sb{2d}\sp{a}$ sequences. ^
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Switzerland has a complex human immunodeficiency virus (HIV) epidemic involving several populations. We examined transmission of HIV type 1 (HIV-1) in a national cohort study. Latent class analysis was used to identify socioeconomic and behavioral groups among 6,027 patients enrolled in the Swiss HIV Cohort Study between 2000 and 2011. Phylogenetic analysis of sequence data, available for 4,013 patients, was used to identify transmission clusters. Concordance between sociobehavioral groups and transmission clusters was assessed in correlation and multiple correspondence analyses. A total of 2,696 patients were infected with subtype B, 203 with subtype C, 196 with subtype A, and 733 with recombinant subtypes (mainly CRF02_AG and CRF01_AE). Latent class analysis identified 8 patient groups. Most transmission clusters of subtype B were shared between groups of gay men (groups 1-3) or between the heterosexual groups "heterosexual people of lower socioeconomic position" (group 4) and "injection drug users" (group 8). Clusters linking homosexual and heterosexual groups were associated with "older heterosexual and gay people on welfare" (group 5). "Migrant women in heterosexual partnerships" (group 6) and "heterosexual migrants on welfare" (group 7) shared non-B clusters with groups 4 and 5. Combining approaches from social and molecular epidemiology can provide insights into HIV-1 transmission and inform the design of prevention strategies.
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We have analyzed the effect of antibodies (Abs) directed against major histocompatibility complex (MHC) class II Abs on the proliferation of Theileria parva-infected (Tpi) T cells. Anti-MHC class II Abs exert a direct effect on Tpi T cells causing an acute block in their proliferation. The inhibition does not involve apoptosis and is also entirely reversible. The rapid arrest of DNA synthesis caused by anti-MHC class II Abs is not due to interference with the state of activation of the T cells since the transcriptional activator NF-kappa B remains activated in arrested cells. In addition, interleukin 2 (IL-2), IL-2R, and c-myc gene expression are also unaffected. By analyzing the cell-cycle phase distribution of inhibited cells, it could be shown that cells in all phases of the cell cycle are inhibited. The signal transduction pathway that results in inhibition was shown to be independent of protein kinase C and extracellular Ca2+. Tyrosine kinase inhibitors, however, partly reduced the level of inhibition and, conversely, phosphatase inhibitors enhanced it. The possible relevance of this phenomenon in other systems is discussed.
Resumo:
A series of studies were undertaken to analyze and compare various aspects of murine class I glycoproteins. An initial area of investigation characterized the Qa-1 alloantigens using two-dimensional gel electrophoresis. Analysis of the products of the Qa-1('b), Qa-1('c) and Qa-1('d) alleles indicated that these were distinct molecules as determined by their lack of comigration upon comparative two-dimensional gel analysis. The importance of asparagine-linked glycosylation in the cell surface expression of class I molecules was also examined. These studies employed tunicamycin, an inhibitor of N-linked glycosylation. Tunicamycin treatment of activated T lymphocytes diminished the surface expression of Qa-1 to undetectable levels; the levels of other class I molecules exhibited little or no decrease. These results indicated that N-linked glycosylation has a differential importance in the cell surface expression of various class I molecules. The molecular weight diversity of class I molecules was also investigated. Molecular weight determination of both the fully glycosylated and unglycosylated forms of H-2 and Qa/Tla region encoded molecules established that there is a significant variation in the sizes of these forms of various class I molecules. The most significant difference ((TURN)9,000 daltons) exists between the unglycosylated forms of H-2K('b) and Qa-2, suggesting that the structural organization of these two molecules may be very different. A comparative two-dimensional gel analysis of various class I glycoproteins isolated from resting and activated T and B lymphocytes indicated that class I molecules expressed on activated T cells exhibited an isoelectrophoretic pattern that was distinct from the isoelectrophoretic pattern of class I molecules expessed on the other cell populations. This difference was attributed to a lower sialic acid content of the molecules expressed on activated T cells. Analysis of cell homogenates determined that activated T cells contained a higher level of endogenous neuraminidase activity than was detected in the other populations, suggesting that this may be the basis of the lower sialic acid content. The relationship of the Qa-4 and Qa-2 alloantigens was also examined. It was established that upon mitogen activation, the expression of Qa-4 was greatly decreased, whereas Qa-2 expression was not decreased. However, an anti-Qa-2 monoclonal antibody blocked the binding of an anti-Qa-4 monoclonal antibody to resting cells. These studies established that Qa-4 is a determinant restricted to resting cells, which is closely associated on the surface with the Qa-2 molecule. ^
Resumo:
Previous studies have led to the development of allochimeric class I MHC proteins as agents that effectively induce donor-specific transplantation tolerance in a rat system with or without additional immunosuppression. Within the α1-helical region of RT1.Au, an epitope that conferred immunologic tolerance was discovered. Studies presented herein were designed to test our central hypothesis that allochimeric proteins onfer tolerance in a mouse model. To test this hypothesis, portal vein (PV) injection of wild-type H2Kd and H2Dd proteins were produced in a bacterial expression system and found to specifically prolong the survival of BALB/c (H2d) heart allografts in C57BL/10 (H2b) recipients. Although a single PV injection of 50 μg α1–α 3 H2Kd alone was ineffective, 50 μg α1 –α3 alone slightly prolonged BALB/c heart allograft survivals. In contrast, the combination of 25 μg α1–α 3 H2Kd and 25 μg α1–α 3 H2Dd proteins prolonged BALB/c graft survivals to 20.2 ± 6.4 days (p < 0.004). The effect was donor-specific, since a combination of 25 μg α1–α3 H2Kd and 25 μg α1–α3 H2Dd proteins failed to affect survivals of third-party C3H (H2k k) heart allografts, namely 9.0 ± 0.0 days in treated versus 7.8 ± 0.5 days in untreated hosts. Thus, the combination of two H2K d and H2Dd proteins is more effective in prolonging allograft survival than a single protein produced in a bacterial expression system. A single PV injection (day 0) of 25 μg α1–α 2 H2Kd and 25 μg α1–α 2 H2Dd proteins to C57BL/10 mice prolonged the survival of BALB/c heart allografts to 22.4 ± 4.5 days. Within a WF to ACI rat heart allograft system, a single PV injection of 20 μg 70–77 u-RT1.Aa induced specific tolerance of allografts. This therapy could be combined with CsA to induce transplantation tolerance. However, combination of 70–77u-RT1.Aa with CTLA4Ig, rapamycin, or AG-490 effectively blocked the induction of transplantation tolerance. Tolerance generated by allochimeric protein could be adoptively transferred to naive recipients. Intragraft cytokine mRNA levels showed a bias towards a Th2-type phenotype. Additionally, studies of cytokine signaling and activation of transcription factors revealed a requirement that these pathways remain available for signaling in order for transplantation tolerance to occur. These studies suggest that the generation of regulatory cells are required for the induction of transplantation tolerance through the use of allochimeric proteins. ^
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"On the Sociology of Class Relations" (GS 12, S.75-104); 1. 1943 Aufsatz. a) Typoskript mit handschriftlichen Korrekturen, 34 Blatt b) Typoskript mit eigenhändigen Korrekturen, 31 Blatt c) Typoskript, 31 Blatt und eigenhändigen Ergänzungen, 1 Blatt d) Typoskript mit eigenhändigen Korrekturen, 26 Blatt; 2. Franz Neumann: 1 eigenhändiger Brief mit Unterschrift an Max Horkheimer mit Anmerkungen zum Aufsatz, ohne Ort, 30.09.1943, 11 Blatt; "The Psychology of Nazidom" (GS 5, S. 354-359); 1. Buchbesprechung von "Is Germany Inucable?" von Richard M. Brickner; veröffentlicht in: "The New Leader", 14.08.1943. a)Typoskript, 7 Blatt b) Typoskript mit eigenhändigen und handschriftlichen Korrekturen, 7 Blatt c) Zeitungsdruck, 3 Exemplare; 2. "What Shall We Do With Germany? A Panel Discussion of 'Is Germany Incurable?'". Zeitungsausschnitte aus : "The Saturday Review of Literature", 29.05.1343, 6 Blatt;
Resumo:
Modern transmitters usually have to amplify and transmit signals with simultaneous envelope and phase modulation. Due to this property of the transmitted signal, linear power amplifiers (class A, B, or AB) are usually used as a solution for the power amplifier stage. These amplifiers have high linearity, but suffer from low efficiency when the transmitted signal has high peak-to-average power ratio. The Kahn envelope elimination and restoration technique is used to enhance the efficiency of RF transmitters, by combining highly efficient, nonlinear RF amplifier (class E) with a highly efficient envelope amplifier in order to obtain a linear and highly efficient RF amplifier. This paper presents a solution for the envelope amplifier based on a multilevel converter in series with a linear regulator. The multilevel converter is implemented by employing voltage dividers based on switching capacitors. The implemented envelope amplifier can reproduce any signal with a maximum spectral component of 2 MHz and give instantaneous maximum power of 50 W. The efficiency measurements show that when the signals with low average value are transmitted, the implemented prototypes have up to 20% higher efficiency than linear regulators used as a conventional solution.
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In a previous work, deduced amino acid sequences from twenty wheat peroxidase genes were assigned to seven groups designated as TaPrx108 to TaPrx114. Some of these apoplastic peroxidases have previously shown to play different roles in the plant defense responses to infection by the cereal cyst nematode Heterodera avenae. In the present study, PCR marker analysis using Sears’s aneuploid wheat lines cv. ‘Chinese Spring’ was used to locate four genes encoding peroxidase isozymes. The TaPrx111-A, TaPrx112-D and TaPrx113-F genes were located on the short arm of chromosome 2B and the TaPrx109-C on the long arm of chromosome 1B. These results would agree with the synteny between wheat and rice chromosomes previously established in other studies.
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A workflow-centric research object bundles a workflow, the provenance of the results obtained by its enactment, other digital objects that are relevant for the experiment (papers, datasets, etc.), and annotations that semantically describe all these objects. In this paper, we propose a model to specify workflow-centric research objects, and show how the model can be grounded using semantic technologies and existing vocabularies, in particular the Object Reuse and Exchange (ORE) model and the Annotation Ontology (AO).We describe the life-cycle of a research object, which resembles the life-cycle of a scienti?c experiment.