Key Points Question What is the risk of recall and high-risk recall for devices undergoing US Food and Drug Administration (FDA) 510(k) clearance compared with premarket approval (PMA)? Findings In this cohort study using the FDA’s 510(k) and PMA medical device database, 28 556 devices were reviewed. Although 97% of recalled devices had received 510(k) clearance, devices with PMA had 2.7 times the hazard of recall and 7.3 times the hazard of high-risk recall compared with devices with 510(k) clearance. Meaning This study suggests that, despite the requirement of clinical trials, high-risk devices approved via PMA were associated with greater safety concerns than previously reported; in addition, most recalls are for 510(k) devices, raising safety issues.

Pyridoxine reaction with (1)O(2) in aqueous solution at neutral pH resulted in oxidation at the 2- and 6-positions of the pyridine ring and unprecedented ring contraction. Kinetic and low temperature studies provided observable intermediates by NMR spectroscopy. In addition, novel cycloaddition between pyridoxine and N-methylmaleimide, without N-alkylation and in water, suggest a common [3 + 2] cycloaddition with the 3-hydroxypyridine ring.

An isolated metaphyseal lesion is not pathognomonic for child abuse, and a thoughtful differential diagnosis should be considered.