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Exchange-coupled hard and soft magnetic layers find extensive use in data storage applications, for which their dynamical response has great importance. With bulk techniques, such as ferromagnetic resonance (FMR), it is difficult to access the behaviour and precise influence of each individual layer. By contrast, the synchrotron radiation-based technique of x-ray detected ferromagnetic resonance (XFMR) allows element-specific and phase-resolved FMR measurements in the frequency range 0.5–11 GHz. Here, we report the study of the magnetization dynamics of an exchange-coupled Ni0.81Fe0.19 (43.5 nm)/Co0.5Fe0.5 (30 nm) bilayer system using magnetometry and vector network analyser FMR, combined with XFMR at the Ni and Co L2 x-ray absorption edges. The epitaxially grown bilayer exhibits two principal resonances denoted as the acoustic and optical modes. FMR experiments show that the Kittel curves of the two layers cannot be taken in isolation, but that their modelling needs to account for an interlayer exchange coupling. The angular dependence of FMR indicates a collective effect for the modes of the magnetically hard CoFe and soft NiFe layer. The XFMR precessional scans show that the acoustic mode is dominated by the Ni signal with the Co and Ni magnetization precessing in phase, whereas the optical mode is dominated by the Co signal with the Co and Ni magnetization precessing in anti-phase. The response of the Co signal at the Ni resonance, and vice versa, show induced changes in both amplitude and phase, which can be ascribed to the interface exchange coupling. An interesting aspect of phase-resolved XFMR is the ability to distinguish between static and dynamic exchange coupling. The element-specific precessional scans of the NiFe/CoFe bilayer clearly have the signature of static exchange coupling, in which the effective field in one layer is aligned along the magnetization direction of the other layer. [ABSTRACT FROM AUTHOR]

Oral feeding of proteins causes peripheral T-cell tolerance, as revealed by reduced delayed-type hypersensitivity (DTH) reactivity after immunization. This type of tolerance can be due both to passive T-cell anergy and active immunosuppression. Using ovalbumin-fed mice we studied whether putatively immunostimulatory cytokines could break this state of mucosal tolerance. Cytokines were administered locally at the site of attempted sensitization. It was found that neither interleukin-2 (IL-2), interferon-γ (IFN-γ) nor granulocyte-macrophage colony-stimulating factor (GM-CSF) could restore the response to immunization. In contrast, local administration of IL-12 at the site of attempted immunization resulted in full recovery of DTH reactivity. The dichotomy between the two Th1 stimulatory cytokines IFN-γ and IL-12 was also reflected by different effects on ovalbumin-specific antibody isotypes. Although both IFN-γ and IL-12 downregulated serum IgG1-levels in tolerant mice, suggesting decreased ovalbumin-specific Th2 function, only local administration of IL-12 led to increased serum IgG2a levels. These results support the view that potentiation of Th1 effector function is critical for reversal of mucosal tolerance. [ABSTRACT FROM AUTHOR]

Background:Hyperthyroidism of Graves'' disease is caused by auto-antibodies to human thyrotropin receptor (hTSH-R). To elucidate important T-cell epitopes in TSH-R, we studied three models of immunity to TSH-R in mice.Methods:Mice transgenic for histocompatibility leukocyte antigen DR3 or DR2 were immunized with cDNA for hTSH-R-extracellular domain (hTSH-R-ECD), or hTSH-R-ECD protein, or hTSH-R peptide epitopes. Proliferative responses of immunized splenocytes to epitopes derived from the hTSH-ECD sequence, anti-TSH-R antibody responses, serum thyroxine and TSH, and thyroid histology were recorded.Results:DR3 mice responded to genomic immunization with proliferative responses to several epitopes, which increased in intensity and spread to include more epitopes, during a 6-week immunization program. DR2 transgenic mice developed weak proliferative responses. Both types of mice developed anti-TSH-R antibodies measured by enzyme-linked immunosorbent assay or TSH-binding inhibition assay in 16–60% of animals. There was evidence of weak thyroid stimulation in one group of animals. Immunization of DR3 transgenic mice to hTSH-R-ECD protein induced a striking response to an epitope with sequence ISRIYVSIDVTLQQLES (aa78–94). Immunization to peptides derived from the TSH-R-ECD sequence (including aa78–94) caused strong responses to the epitopes, and development of immune responses to several other nonoverlapping epitopes within the hTSH sequence (epitope spreading) and antibodies reacting with hTSH-R. This implies that immunization with hTSH-R epitopes produced immunity to mouse TSH-R.Conclusion:T-cell and B-cell responses to genetic immunization differ in DR3 and DR2 transgenic mice, and there is less genetic control of antibody than of T-cell responses. During both genomic and peptide epitope immunization there was evidence of epitope spreading during the immunization. Several functionally important epitopes are evident, especially aa78–94. However, if similar progressive epitope recruitment occurs in human disease, epitope-based therapy will be difficult to achieve. [ABSTRACT FROM AUTHOR]

Novel fluorescent derivatives of dofetilide (1) have been synthesized. Analogues that feature a fluorescent probe attached through an aliphatic spacer to the central tertiary nitrogen of 1have high affinity for the hERG channel, and affinity is dependent on both linker length and pendent dye. These variables have been optimized to generate Cy3B derivative 10e, which has hERG channel affinity equivalent to that of dofetilide. When bound to cell membranes expressing the hERG channel, 10eshows a robust increase in fluorescence polarization (FP) signal. In a FP binding assay using 10eas tracer ligand, Kivalues for several known hERG channel blockers were measured and excellent agreement with the literature Kivalues was observed over an affinity range of 2 nM to 3 M. 10eblocks hERG channel current in electrophysiological patch clamp experiments, and computational docking experiments predict that the dofetilide core of 10ebinds hERG channel in a conformation similar to that previously predicted for 1. These analogues enable high-throughput hERG channel binding assays that are rapid, economical, and predictive of test compounds' potential for prolonged QT liabilities. [ABSTRACT FROM AUTHOR]

Two radiolabeled bicyclic nucleoside analogues (BCNAs) were synthesized, namely 3-(2‘-deoxy--d-ribofuranosyl)-6-(3-18Ffluoroethoxyphenyl)-2,3-dihydrofuro2,3-dpyrimidin-2-one (18F-2) and 3-(2‘-deoxy--d-ribofuranosyl)-6-(3-11Cmethoxyphenyl)-2,3-dihydrofuro2,3-dpyrimidin-2-one (11C-3), and evaluated as PET reporter probes for varicella-zoster virus thymidine kinase (VZV-tk) gene expression imaging in brain. 18F-2and 11C-3were synthesized starting from phenol precursor 1. The phenol precursor 1was converted to stable as well as to radiolabeled compounds 2and 3using 1918FCH2CH2Br or 1211CH3I as alkylating agent. In vitro evaluation of 18F-2and 11C-3in 293T cells showed a 4.5 and 53-fold higher uptake, respectively, into VZV-tk gene-transduced cells compared to control cells. However, biodistribution studies in mice demonstrated low uptake of these tracers in the brain. RP-HPLC analysis of plasma and urine samples of mice injected with 11C-3revealed that this tracer is very stable in vivo. These data warrant further evaluation of these tracers as noninvasive imaging agents for VZV infection and VZV-tk reporter gene expression in vivo. [ABSTRACT FROM AUTHOR]

Toroviruses (order Nidovirales) are enveloped positive-strand RNA viruses of mammals. The prototype torovirus, equine torovirus strain Berne (Berne virus [BEV]), uses two different transcription strategies to produce a 3′-coterminal nested set of subgenomic (sg) mRNAs. Its mRNA 2 carries a leader sequence derived from the 5′ end of the genome and is produced via discontinuous transcription. The remaining three sg mRNAs, 3 to 5, are colinear with the 3′ end of the genome and are made via non-discontinuous RNA synthesis. Their synthesis is supposedly regulated by short conserved sequence motifs, 5′-ACN3–4CUUUAGA-3′, within the noncoding intergenic regions that precede the M, HE, and N genes (A. L. van Vliet, S. L. Smits, P. J. Rottier, and R. J. de Groot, EMBO J. 21:6571–6580, 2002). We have now studied the—for nidoviruses unusual—non- discontinuous transcription mechanism in further detail by probing the role of the postulated transcription- regulating sequences (TRSs). To this end, we constructed a synthetic defective interfering (DI) RNA, carrying a 24-nucleotide segment of the intergenic region between the HE and N genes. We demonstrate that this DI RNA, when introduced into BEV-infected cells, directs the synthesis of a sg DI RNA species; in fact, a 16-nucleotide cassette containing the TRS already proved sufficient. Synthesis of this sg DI RNA, like that of mRNAs 3 to 5 of the standard virus, initiated at the 5′-most adenylate of the TRS. An extensive mutational analysis of the TRS is presented. Our results provide first and formal experimental evidence that the conserved motifs within the BEV intergenic sequences indeed drive sg RNA synthesis. [ABSTRACT FROM AUTHOR]