Equal but Separate: The Slow Assimilation of Osteopathic Surgery Residents Two Years After the Unified Match.

OBJECTIVES: The purpose of this study was to monitor the integration of general surgery residency programs before and after the 2020 unified match. We hypothesized that integration of osteopathic (DO) surgery residents would increase. DESIGN: We performed a retrospective cohort study of surgery residency programs between 2019 and 2021 utilizing data provided by the Association of American Medical Colleges. Program composition (2021) and changes in composition (2019-2021) were compared by program type. Multivariable logistic regression models assessed variables associated with DO presence (2021) and integration (2019-2021). SETTING: General surgery residency programs across the United States. PARTICIPANTS: Civilian surgery residencies that completed the 2019-2021 program survey. RESULTS: Out of 320 programs, DO residents were integrated at 69% (221/320), including 52% (63/122) university programs, 78% (101/129) university-affiliated programs and 83% (57/69) community programs (p < 0.01). Overall, 23 (8%) programs integrated DO residents from 2019 to 2021, and 9 (21%) ex-American Osteopathic Association programs integrated MD residents (both p < 0.01). The median number of DO residents was 1 (interquartile range, IQR 0-2) at university programs, 2 (IQR 1-7) at university-affiliated programs, and 5 (IQR 2-12) at community programs (p < 0.01). The median number of DO residents at all programs increased from 1 (IQR 0-5) to 2 (IQR 0-6) since 2019 (p < 0.01). Community (OR 2.6, p = 0.04), university-affiliated (OR 2.3, p = 0.02), and programs with DOs in 2019 (OR 19.0, p < 0.01) were associated with increased odds of DOs present in 2021, while DO faculty (OR 2.6, p = 0.02) was the only factor independently associated with integrating DOs after 2019. CONCLUSIONS: While some programs have integrated DO residents, progress is slow, median numbers of DO residents remain low, and familiarity with DOs is most associated with integration. We explore barriers to integration, and advance recommendations to eliminate potential disparities.

Cardiac MLC2 kinase is localized to the Z-disc and interacts with α-actinin2.

Cardiac contractility is enhanced by phosphorylation of myosin light chain 2 (MLC2) by cardiac-specific MLC kinase (cMLCK), located at the neck region of myosin heavy chain. In normal mouse and human hearts, the level of phosphorylation is maintained relatively constant, at around 30-40% of total MLC2, likely by well-balanced phosphorylation and phosphatase-dependent dephosphorylation. Overexpression of cMLCK promotes sarcomere organization, while the loss of cMLCK leads to cardiac atrophy in vitro and in vivo. In this study, we showed that cMLCK is predominantly expressed at the Z-disc with additional diffuse cytosolic expression in normal adult mouse and human hearts. cMLCK interacts with the Z-disc protein, α-actinin2, with a high-affinity kinetic value of 13.4 ± 0.1 nM through the N-terminus region of cMLCK unique to cardiac-isoform. cMLCK mutant deficient for interacting with α-actinin2 did not promote sarcomeric organization and reduced cardiomyocyte cell size. In contrast, a cMLCK kinase-deficient mutant showed effects similar to wild-type cMLCK on sarcomeric organization and cardiomyocyte cell size. Our results suggest that cMLCK plays a role in sarcomere organization, likely distinct from its role in phosphorylating MLC2, both of which will contribute to the enhancement of cardiac contractility.