Case study: failure of superior capsular reconstruction using dermal allograft.

Superior capsular reconstruction (SCR) is a novel technique for treating irreparable rotator cuff tears in younger patients in whom a reverse total shoulder arthroplasty is not the optimal treatment choice. This case study describes a middle-aged male with a recurrent, massive, irreparable rotator cuff tear treated with SCR that subsequently failed at the glenoid attachment. The patient underwent successful arthroscopic revision of the SCR. The case illustrates the MRI and arthroscopic correlations of the failed dermal allograft reconstruction, which to our knowledge has not been previously shown in the radiology literature.

Variation in response to artificial selection for light sensitivity in guppies (Poecilia reticulata).

We performed artificial selection on the visual system in guppies (Poecilia reticulata), using the optomotor reaction threshold as the selection criterion. Two lines were selected for increased sensitivity to blue light, two were selected for increased sensitivity to red light, and two were unselected controls. There was significant response to selection in all four selected lines and significant heritability for sensitivity. An examination of the spectral sensitivity function showed that the form of the response differed between the red and blue lines and among the red lines. Such divergence is likely because there are many different mechanisms allowing response to selection for spectral sensitivity. Diverse mechanisms allow a divergent response by different populations to the same selective pressures. Such a mechanism can promote diversity in vision and visual signals, and any multicomponent system where different components can respond to the same selective regime.