Course of neuromyelitis optica during inadvertent pregnancy in a patient treated with rituximab

In neuromyelitis optica (NMO), the monoclonal B-cell antibody rituximab is a therapeutic option. Little is known about the course of NMO and the safety of rituximab during pregnancy. In this study, we report the clinical course of a patient with NMO after application of rituximab 1 week before inadvertent conception. Mother and child did not experience any adverse event, and the postpartum development of the baby was completely normal up to 15 months. Clinical course of NMO was stable during the entire pregnancy. This case illustrates a favorable outcome in a pregnant NMO patient and her child after therapy with rituximab

Magnetization dynamics in dysprosium orthoferrites via inverse Faraday effect

The ultrafast non-thermal control of magnetization has recently become feasible in canted antiferromagnets through photomagnetic instantaneous pulses [A.V. Kimel {\it et al.}, Nature {\bf 435}, 655 (2005)]. In this experiment circularly polarized femtosecond laser pulses set up a strong magnetic field along the wave vector of the radiation through the inverse Faraday effect, thereby exciting non-thermally the spin dynamics of dysprosium orthoferrites. A theoretical study is performed by using a model for orthoferrites based on a general form of free energy whose parameters are extracted from experimental measurements. The magnetization dynamics is described by solving coupled sublattice Landau-Lifshitz-Gilbert equations whose damping term is associated with the scattering rate due to magnon-magnon interaction. Due to the inverse Faraday effect and the non-thermal excitation, the effect of the laser is simulated by magnetic field Gaussian pulses with temporal width of the order of hundred femtoseconds. When the field is along the z-axis, a single resonance mode of the magnetization is excited. The amplitude of the magnetization and out-of-phase behavior of the oscillations for fields in z and -z directions are in good agreement with the cited experiment. The analysis of the effect of the temperature shows that magnon-magnon scattering mechanism affects the decay of the oscillations on the picosecond scale. Finally, when the field pulse is along the x-axis, another mode is excited, as observed in experiments. In this case the comparison between theoretical and experimental results shows some discrepancies whose origin is related to the role played by anisotropies in orthoferrites.Comment: 10 pages, 6 figure

Nonequilibrium Magnetization Dynamics of Nickel

Ultrafast magnetization dynamics of nickel has been studied for different degrees of electronic excitation, using pump-probe second-harmonic generation with 150 fs/800 nm laser pulses of various fluences. Information about the electronic and magnetic response to laser irradiation is obtained from sums and differences of the SHG intensity for opposite magnetization directions. The classical M(T)-curve can be reproduced for delay times larger than the electron thermalization time of about 280 fs, even when electrons and lattice have not reached thermal equilibrium. Further we show that the transient magnetization reaches its minimum approx. 50 fs before electron thermalization is completed.Comment: 8 pages, 5 figures, revte

Review: ‘Gimme five’: future challenges in multiple sclerosis. ECTRIMS Lecture 2009

This article is based on the ECTRIMS lecture given at the 25th ECTRIMS meeting which was held in Düsseldorf, Germany, from 9 to 12 September 2009. Five challenges have been identified: (1) safeguarding the principles of medical ethics; (2) optimizing the risk/benefit ratio; (3) bridging the gap between multiple sclerosis and experimental autoimmune encephalitis; (4) promoting neuroprotection and repair; and (5) tailoring multiple sclerosis therapy to the individual patient. Each of these challenges will be discussed and placed in the context of current research into the pathogenesis and treatment of multiple sclerosis

Features of MOG required for recognition by patients with MOG antibody-associated disorders

Antibodies to myelin oligodendrocyte glycoprotein (MOG-Abs) define a distinct disease entity. Here we aimed to understand essential structural features of MOG required for recognition by autoantibodies from patients. We produced the N-terminal part of MOG in a conformationally correct form; this domain was insufficient to identify patients with MOG-Abs by ELISA even after site-directed binding. This was neither due to a lack of lipid embedding nor to a missing putative epitope at the C-terminus, which we confirmed to be an intracellular domain. When MOG was displayed on transfected cells, patients with MOG-Abs recognized full-length MOG much better than its N-terminal part with the first hydrophobic domain (P < 0.0001). Even antibodies affinity-purified with the extracellular part of MOG recognized full-length MOG better than the extracellular part of MOG after transfection. The second hydrophobic domain of MOG enhanced the recognition of the extracellular part of MOG by antibodies from patients as seen with truncated variants of MOG. We confirmed the pivotal role of the second hydrophobic domain by fusing the intracellular part of MOG from the evolutionary distant opossum to the human extracellular part; the chimeric construct restored the antibody binding completely. Further, we found that in contrast to 8-18C5, MOG-Abs from patients bound preferentially as F(ab')(2) rather than Fab. It was previously found that bivalent binding of human IgG1, the prominent isotype of MOG-Abs, requires that its target antigen is displayed at a distance of 13-16 nm. We found that, upon transfection, molecules of MOG did not interact so closely to induce a Forster resonance energy transfer signal, indicating that they are more than 6 nm apart. We propose that the intracellular part of MOG holds the monomers apart at a suitable distance for bivalent binding; this could explain why a cell-based assay is needed to identify MOG-Abs. Our finding that MOG-Abs from most patients require bivalent binding has implications for understanding the pathogenesis of MOG-Ab associated disorders. Since bivalently bound antibodies have been reported to only poorly bind C1q, we speculate that the pathogenicity of MOG-Abs is mostly mediated by other mechanisms than complement activation. Therefore, therapeutic inhibition of complement activation should be less efficient in MOG-Ab associated disorders than in patients with antibodies to aquaporin-4

Planck Scale Boundary Conditions and the Higgs Mass

If the LHC does only find a Higgs boson in the low mass region and no other new physics, then one should reconsider scenarios where the Standard Model with three right-handed neutrinos is valid up to Planck scale. We assume in this spirit that the Standard Model couplings are remnants of quantum gravity which implies certain generic boundary conditions for the Higgs quartic coupling at Planck scale. This leads to Higgs mass predictions at the electroweak scale via renormalization group equations. We find that several physically well motivated conditions yield a range of Higgs masses from 127-142 GeV. We also argue that a random quartic Higgs coupling at the Planck scale favors M_H > 150 GeV, which is clearly excluded. We discuss also the prospects for differentiating different boundary conditions imposed for \lambda(M_{pl}) at the LHC. A striking example is M_H = 127\pm 5 GeV corresponding to \lambda(M_{pl})=0, which would imply that the quartic Higgs coupling at the electroweak scale is entirely radiatively generated.Comment: 12 pages, 5 figures; references added and other minor improvements, matches version published in JHE

Dynamics of Excited Electrons in Copper and Ferromagnetic Transition Metals: Theory and Experiment

Both theoretical and experimental results for the dynamics of photoexcited electrons at surfaces of Cu and the ferromagnetic transition metals Fe, Co, and Ni are presented. A model for the dynamics of excited electrons is developed, which is based on the Boltzmann equation and includes effects of photoexcitation, electron-electron scattering, secondary electrons (cascade and Auger electrons), and transport of excited carriers out of the detection region. From this we determine the time-resolved two-photon photoemission (TR-2PPE). Thus a direct comparison of calculated relaxation times with experimental results by means of TR-2PPE becomes possible. The comparison indicates that the magnitudes of the spin-averaged relaxation time \tau and of the ratio \tau_\uparrow/\tau_\downarrow of majority and minority relaxation times for the different ferromagnetic transition metals result not only from density-of-states effects, but also from different Coulomb matrix elements M. Taking M_Fe > M_Cu > M_Ni = M_Co we get reasonable agreement with experiments.Comment: 23 pages, 11 figures, added a figure and an appendix, updated reference