Effect of Instrumented Spine Surgery on Length of Stay.

INTRODUCTION: Total joint arthroplasty studies have identified that surgeries that take place later in the week have a longer length of stay compared with those earlier in the week. This has not been demonstrated in studies focused on anterior cervical diskectomy and fusions or minimally invasive lumbar laminectomies. All-inclusive instrumented spine surgeries, however, have not been analyzed. The purpose of this study was to determine whether day of surgery affects length of stay and whether there are predictive patient characteristics that affect length of stay in instrumented spine surgery. METHODS: All instrumented spine surgeries in 2019 at a single academic tertiary center were retrospectively reviewed. Patients were categorized for surgical day and discharge disposition to home or a rehabilitation facility. Differences by patient characteristics in length of stay and discharge disposition were compared using Kruskal-Wallis and chi square tests along with multiple comparisons. RESULTS: Seven hundred six patients were included in the analysis. Excluding Saturday, there were no differences in length of stay based on the day of surgery. Age older than 75 years, female, American Society of Anesthesiology (ASA) classification of 3 or 4, and an increased Charlson Comorbidity Index were all associated with a notable increase in length of stay. While most of the patients were discharged home, discharge to a rehabilitation facility stayed, on average, 4.7 days longer (6.8 days compared with 2.1 days, on average) and were associated with an age older than 66 years old, an ASA classification of 3 or 4, and a Charlson Comorbidity Index of 1 to 3. CONCLUSIONS: Day of surgery does not affect length of stay in instrumented spine surgeries. Discharge to a rehabilitation facility, however, did increase the length of stay as did age older than 75 years, higher ASA classification, and increased Charlson Comorbidity Index classification.

Solid-phase submonomer synthesis of peptoid polymers and their self-assembly into highly-ordered nanosheets.

Peptoids are a novel class of biomimetic, non-natural, sequence-specific heteropolymers that resist proteolysis, exhibit potent biological activity, and fold into higher order nanostructures. Structurally similar to peptides, peptoids are poly N-substituted glycines, where the side chains are attached to the nitrogen rather than the alpha-carbon. Their ease of synthesis and structural diversity allows testing of basic design principles to drive de novo design and engineering of new biologically-active and nanostructured materials. Here, a simple manual peptoid synthesis protocol is presented that allows the synthesis of long chain polypeptoids (up to 50mers) in excellent yields. Only basic equipment, simple techniques (e.g. liquid transfer, filtration), and commercially available reagents are required, making peptoids an accessible addition to many researchers' toolkits. The peptoid backbone is grown one monomer at a time via the submonomer method which consists of a two-step monomer addition cycle: acylation and displacement. First, bromoacetic acid activated in situ with N,N'-diisopropylcarbodiimide acylates a resin-bound secondary amine. Second, nucleophilic displacement of the bromide by a primary amine follows to introduce the side chain. The two-step cycle is iterated until the desired chain length is reached. The coupling efficiency of this two-step cycle routinely exceeds 98% and enables the synthesis of peptoids as long as 50 residues. Highly tunable, precise and chemically diverse sequences are achievable with the submonomer method as hundreds of readily available primary amines can be directly incorporated. Peptoids are emerging as a versatile biomimetic material for nanobioscience research because of their synthetic flexibility, robustness, and ordering at the atomic level. The folding of a single-chain, amphiphilic, information-rich polypeptoid into a highly-ordered nanosheet was recently demonstrated. This peptoid is a 36-mer that consists of only three different commercially available monomers: hydrophobic, cationic and anionic. The hydrophobic phenylethyl side chains are buried in the nanosheet core whereas the ionic amine and carboxyl side chains align on the hydrophilic faces. The peptoid nanosheets serve as a potential platform for membrane mimetics, protein mimetics, device fabrication, and sensors. Methods for peptoid synthesis, sheet formation, and microscopy imaging are described and provide a simple method to enable future peptoid nanosheet designs.