Validation of a three-dimensional printed pediatric middle ear model for endoscopic surgery training.

Objective: The purpose of this study is to assess the anatomical appropriateness of a three-dimensional (3D) printed pediatric middle ear model with a replaceable middle ear unit as an endoscopic ear surgery (EES) simulator. Methods: Single-blinded, prospective, proof-of-concept study conducted in a simulation operative suite. A simulator was developed through segmentation of source images and multi-material 3D printing. Subjects were asked to point to seven anatomical sites before and after a short anatomy presentation of a human middle ear photograph. They also filled out a survey about the feasibility of the model. Outcome variables included survey scores, pre-anatomy lesson (PreAL) and post-anatomy lesson (PostAL) quiz scores. Results: There were 24 participants (19 residents, 1 fellow, and 4 attendings), none with self-reported proficiency in EES. The PreAL mean score was 4.42 and PostAL quiz mean score was 5.32 (average improvement of 43% [CI = 17%-70%]; p = .003). The higher the level of training, the higher the PreAL scores (0.55 points per year of training; p = .004). The subspecialty (otology, other, in-training) was also associated with the PreAL scores (p = .004). Total survey score means were 22.8 (out of 30). Conclusion: The results of our study suggest that our model has adequate anatomical high fidelity to mimic a real, pediatric temporal bone for EES. As 3D printing technologies continue to advance, the quality of ear models has the potential to provide improved surgical training for pediatric EES. Level of Evidence: 4.

Luteinizing Hormone Dynamics in Menstruation.

Menstruation is a finely-controlled cycle that responds to the prevailing endocrine and paracrine environment. However, social stigma has led to inadequate menstrual literacy, both among academics and the larger public. The poorly understood mechanisms of menstruation ultimately lead to suboptimal healthcare treatment and services for biological females, culminating in a physical, financial, and emotional burden. Various hormones signal the beginning and end of each stage of menstruation. In particular, luteinizing hormone (LH) is a major player in ovulation, corpus luteum function, and the stimulation of other key hormones. A LH model could be used to understand the larger control system of menstruation if analyzed in conjunction with models for other major hormones (e.g., FSH, progesterone, and GnRH). Thus, exploring a smaller subsection of LH dynamics within the larger control system of menstruation can lead to a greater understanding of menstruation, contributing towards therapeutics and research for women's health. Using parameters and kinetic equations in the existing body of literature, a transfer function was derived to model LH dynamics. Analysis of system stability reveals overdamped dynamics in LH sensitization at baseline, and underdamped mildly resonant dynamics at the peak of the menstrual cycle, the strength of which depends on the values of the rate constants of LH receptor formation, binding, and desensitization.