Magnetomicrometry.

We live in an era of wearable sensing, where our movement through the world can be continuously monitored by devices. Yet, we lack a portable sensor that can continuously monitor muscle, tendon, and bone motion, allowing us to monitor performance, deliver targeted rehabilitation, and provide intuitive, reflexive control over prostheses and exoskeletons. Here, we introduce a sensing modality, magnetomicrometry, that uses the relative positions of implanted magnetic beads to enable wireless tracking of tissue length changes. We demonstrate real-time muscle length tracking in an in vivo turkey model via chronically implanted magnetic beads while investigating accuracy, biocompatibility, and long-term implant stability. We anticipate that this tool will lay the groundwork for volitional control over wearable robots via real-time tracking of muscle lengths and speeds. Further, to inform future biomimetic control strategies, magnetomicrometry may also be used in the in vivo tracking of biological tissues to elucidate biomechanical principles of animal and human movement.

A practical metaphase marker of the inactive X chromosome.

It is paradoxical that the inactivated X is the only chromosome that can be identified in the interphase nucleus, yet in metaphase, it is indistinguishable from its genetically active homolog unless special culture and staining procedures are employed. A specific inactivation-associated fold in proximal Xq resolves that paradox. We describe here how the fold in the proximal long arm can be used as a simple and reliable marker to identify the inactivated X in G-, Q-, or R-banded preparations. Several examples are given, including localization of the inactivation center to band Xq13 or q21.1, identification of nonrandom inactivation in X-chromosome rearrangements, identification of multiple active X chromosomes in tumor cell lines, analysis of X-inactivation patterns in female carriers of the fragile site at Xq27, and comparison of X-inactivation patterns among primate species.

De novo paracentric inversion in an X chromosome.

A 10 1/2 year old female with skeletal abnormalities was referred for genetic consultation because of learning disabilities and a suggestion of 'Turner-like' stigmata. Cytogenetic analysis revealed a paracentric inversion of an X(q13.1q26.1) chromosome.

De novo interstitial direct duplication of 15q: 46,XY,dir dup(15) (pter leads to q24::q14 leads to q21 X 1::q24 leads to qter).

A profoundly retarded, slightly dysmorphic male was re-examined cytogenetically by high resolution GTG banding and found to have a de novo interstitial direct duplication of 15q.