Objective. There is evidence supporting a therapeutic range for methotrexate polyglutamate ( Conclusion. There is wide interpatient variability of RBC MTXGlu 1-5 accumulation and elimination in adults with RA. These data also suggest that after a dose change, >6 months are required for RBC MTXGlu 1-5 to reach steady state. Such delays in achieving steady state suggest that more rapid dose escalation or subcutaneous administration from the outset should be considered.

▪ Abstract  Solar coronal mass ejections (CMEs) are a major form of activity on the Sun. A CME takes 1015-16 g of plasma from the low corona into the solar wind, to disturb the near-Earth space if the CME direction is favorable. We summarize current observations and ideas of CME physics to provide a hydromagnetic view of the CMEs as the products of continual magnetic flux emergence and an interplay between magnetic reconnection and approximate magnetic-helicity conservation in the corona. Each flux emergence brings helicity to accumulate additively in a coronal structure while excess magnetic energy is flared away by reconnection. Self-confinement eventually fails with a CME shedding the accumulated helicity out of the low corona to enable the field to reach the minimum-energy state. Similar evolutionary processes may occur in other magnetic stars and galaxies.

A loss of magnetic field confinement is believed to be the cause of coronal mass ejections (CMEs), a major form of solar activity in the corona. The mechanisms for magnetic energy storage are crucial in understanding how a field may possess enough free energy to overcome the Aly limit and open up. Previously, we have pointed out that the accumulation of magnetic helicity in the corona plays a significant role in storing magnetic energy. In this paper, we investigate another hydromagnetic consequence of magnetic-helicity accumulation. We propose a conjecture that there is an upper bound on the total magnetic helicity that a force-free field can contain. This is directly related to the hydromagnetic property that force-free fields in unbounded space have to be self-confining. Although a mathematical proof of this conjecture for any field configuration is formidable, its plausibility can be demonstrated with the properties of several families of power-law, axisymmetric force-free fields. We put forth mathematical evidence, as well as numerical, indicating that an upper bound on the magnetic helicity may exist for such fields. Thus, the accumulation of magnetic helicity in excess of this upper bound would initiate a nonequilibrium situation, resulting in a CME expulsion as a natural product of coronal evolution.