Single-molecule imaging (SMI) has been widely utilized to investigate biomolecular dynamics and protein-protein interactions in living cells. However, multicolor SMI of intracellular proteins is challenging because of high background signals and other limitations of current fluorescence labeling approaches. To achieve reproducible intracellular SMI, a labeling probe ensuring both efficient membrane permeability and minimal non-specific binding to cell components is essential. We developed near-infrared fluorescent probes for protein labeling that specifically bind to a mutant β-lactamase tag. By structural fine-tuning of cell permeability and minimized non-specific binding, SiRcB4 enabled multicolor SMI in combination with a HaloTag-based red-fluorescent probe. Upon addition of both chemical probes at sub-nanomolar concentrations, single-molecule imaging revealed the dynamics of TLR4 and its adaptor protein, TIRAP, which are involved in the innate immune system. Statistical analysis of the quantitative properties and time-lapse changes in dynamics revealed a protein-protein interaction in response to ligand stimulation.

Peak mobility function and mobility decline occurred at a younger age in GMFCS level III, with the cause of mobility decline differing by GMFCS level.

A new electric powet assist unit for wheelchairs (JW-II; YAMAHA MOTOR Co., LTD.) has become available. With this unit, a little muscle power is needed to drive the handrim. The usefulness of this unit was clinically evaluated for four patients with Duchenne muscular dystrophy (DMD). None of the patients were ambulatory, and their upper limb muscular power was gravity eliminated. Although they had decreased muscle power, all four patients were able to drive their wheelchairs. Neither roll down nor pile up accidents occurred. The maximum heart rate during driving increased approximately 33% on average above that at rest. In addition, the patients felt that they could drive their wheelchairs by themselves without electrical power assist, unlike ordinary electric wheelchairs. This new unit appears to be safe and useful for DMD patients in expanding their ADL.