Surgical Management of Polymethylmethacrylate-Collagen Gel Complications in the Lower Eyelid: A Case Series.

BACKGROUND: As nonsurgical rejuvenation with fillers continues to grow in popularity, patients are increasingly interested in more durable results. Polymethylmethacrylate (PMMA)-collagen gel is unique among fillers in that the PMMA microspheres are not completely absorbed and phagocytosed by the body. This durability coupled with the biophysical properties of PMMA makes it a poor choice for periorbital rejuvenation, an unforgiving and highly complex anatomic area. METHODS: Between 2011 and 2018, 14 patients with PMMA granulomas in various facial areas self-referred to the senior author's practice. Of these patients, 11 were managed nonsurgically; however, all 3 patients who presented with granulomas in the infraorbital area required surgery to remove the filler and restore a natural aesthetic. RESULTS: The 3 patients with significant swelling and PMMA filler nodules in the infraorbital area with unacceptable cosmetic appearance were females between the ages of 50 and 55 years. Nonsurgical protocols were unsuccessful, and surgical removal was required. All subjects have been followed for a minimum of 2 years with no immediate- or long-term postoperative complications secondary to PMMA removal. Patients remain satisfied with the outcome of the surgery. CONCLUSIONS: Despite the evidence that the periorbital area is prone to adverse events when injected with particulate fillers, misguided enthusiasm for PMMA-collagen gel as a durable treatment continues to lead to unnecessary and severe complications in patients. The case studies presented here highlight that this product should not be introduced into the periorbital area. We also describe a surgical treatment approach for its removal if complications arise.

Anti-Correlation between the Dynamics of the Active Site Loop and C-Terminal Tail in Relation to the Homodimer Asymmetry of the Mouse Erythroid 5-Aminolevulinate Synthase.

Biosynthesis of heme represents a complex process that involves multiple stages controlled by different enzymes. The first of these proteins is a pyridoxal 5'-phosphate (PLP)-dependent homodimeric enzyme, 5-aminolevulinate synthase (ALAS), that catalyzes the rate-limiting step in heme biosynthesis, the condensation of glycine with succinyl-CoA. Genetic mutations in human erythroid-specific ALAS (ALAS2) are associated with two inherited blood disorders, X-linked sideroblastic anemia (XLSA) and X-linked protoporphyria (XLPP). XLSA is caused by diminished ALAS2 activity leading to decreased ALA and heme syntheses and ultimately ineffective erythropoiesis, whereas XLPP results from "gain-of-function" ALAS2 mutations and consequent overproduction of protoporphyrin IX and increase in Zn2+-protoporphyrin levels. All XLPP-linked mutations affect the intrinsically disordered C-terminal tail of ALAS2. Our earlier molecular dynamics (MD) simulation-based analysis showed that the activity of ALAS2 could be regulated by the conformational flexibility of the active site loop whose structural features and dynamics could be changed due to mutations. We also revealed that the dynamic behavior of the two protomers of the ALAS2 dimer differed. However, how the structural dynamics of ALAS2 active site loop and C-terminal tail dynamics are related to each other and contribute to the homodimer asymmetry remained unanswered questions. In this study, we used bioinformatics and computational biology tools to evaluate the role(s) of the C-terminal tail dynamics in the structure and conformational dynamics of the murine ALAS2 homodimer active site loop. To assess the structural correlation between these two regions, we analyzed their structural displacements and determined their degree of correlation. Here, we report that the dynamics of ALAS2 active site loop is anti-correlated with the dynamics of the C-terminal tail and that this anti-correlation can represent a molecular basis for the functional and dynamic asymmetry of the ALAS2 homodimer.