Combined endoscopic and open approach to the removal of expandable metallic tracheal stents.

OBJECTIVES: To review complications of indwelling tracheal stents and to describe a technique of stent removal using a combined open and endoscopic approach. DESIGN: Descriptive case series. SETTING: Medical University of South Carolina. PATIENTS: Six patients were identified who had undergone combined open and endoscopic removal of indwelling tracheal stents. Coated (4 patients) and uncoated (2 patients) expandable metal stents had been present for an average time of 24 months (range, 5-60 months) before removal. MAIN OUTCOME MEASURES: Medical comorbidities, characteristics of the underlying airway lesion (origin, type, and length), stent characteristics (type and duration), and the presentation and management of stent-related complications. RESULTS: All patients presented with worsening dyspnea and/or stridor, with 3 requiring intubation. Stent removal was performed in the operating room and consisted of initial exposure of the trachea for emergency airway access, removal of the indwelling stent under bronchoscopic and transtracheal guidance, and tracheotomy. Two patients experienced desaturations of more than 25% during the procedure, and 2 patients had stents that could be only partially removed. Five patients subsequently received Montgomery T-tubes without complications after a mean follow-up of 23 months (range, 6-40 months). CONCLUSIONS: Indwelling tracheal stents are becoming increasingly common in the management of benign airway stenosis. The stents frequently occlude with granulation tissue and may require removal. A combined open and endoscopic removal maximizes airway protection and minimizes potential complications.

Characterization of the heterogeneous binding site affinity distributions in molecularly imprinted polymers.

Molecularly imprinted polymers (MIPs) are polymers that can be tailored with affinity and selectivity for a molecule of interest. Offsetting the low cost and ease of preparation of MIPs is the presence of binding sites that vary widely in affinity and selectivity. Presented is a review of methods that take into account binding site heterogeneity when calculating the binding properties of MIPs. These include the bi-Langmuir, Freundlich, and Langmuir-Freundlich binding models. These methods yield a measure of heterogeneity in the form of binding site affinity distributions and the heterogeneity index. Recent developments have made these methods surprisingly easy to use while also yielding more accurate measures of the binding properties of MIPs. These have allowed for easier comparison and optimization of MIPs. Heterogeneous binding models have also led to a better understanding of the imprinting process and of the advantages and limitations of MIPs in chromatographic and sensor applications.

Immunolocalization of dendritic cells and pattern recognition receptors in chronic rhinosinusitis.

BACKGROUND: Dendritic cell (DC) activation and antigen presentation to T cells are critical to innate and adaptive immunity. Toll-like receptors (TLRs) are known to bind pathogen-associated molecular patterns in addition to sinonasally secreted surfactant proteins (SP) such as SP-A and SP-D. TLR binding is known to activate DCs. Based on these observations, we sought to establish the presence, in sinonasal mucosa, of DC and the pattern recognition receptors (PRRs), CD14, TLR2, and TLR4. METHODS: Sinonasal biopsy specimens were taken from patients with eosinophilic nonatopic nasal polyposis (n = 4), allergic fungal sinusitis (n = 1), and nondiseased patients undergoing cerebrospinal fluid leak repair or pituitary tumor resection (n = 2). Tissue samples were stained immunohistochemically for PRR (CD14, TLR2, and TLR4), mature DC marker (CD208), iDC marker (CD209), or isotype controls. RESULTS: Immature and mature DC were immunolocalized to the subepithelial stroma and ciliated epithelial surface, respectively. Diffuse staining of CD14 was observed throughout the stroma with additional staining in the ciliated epithelium. The TLR markers showed no staining in the ciliated epithelium. TLR2 primarily localized in stroma immediately deep to the ciliated epithelial surface. TLR4 immunolocalized to submucosal seromucinous gland ductal epithelium. Data from nondiseased patients were mixed, with one patient showing minimal staining of any of the tested cellular markers. CONCLUSION: This study indicates progressive DC activation and emigration of mature antigen-presenting cells from the epithelial surfaces of sinonasal mucosa. The presence of TLR known to bind SP-A and SP-D suggests a link between SP expression and immune response in sinonasal mucosa.

Characterization of the imprint effect and the influence of imprinting conditions on affinity, capacity, and heterogeneity in molecularly imprinted polymers using the Freundlich isotherm-affinity distribution analysis.

Molecularly imprinted polymers (MIPs) have been used in a wide range of analytical applications in particular in chromatography and sensing. However, the binding properties in MIPs are typically measured only in a narrow concentration range, which corresponds to only a subset of the sites in MIPs. This limited analytical window and binding site heterogeneity of MIPs leads to inaccuracies and inconsistencies in the estimation of their binding properties. This has hampered the characterization and optimization of MIPs for analytical applications. In this study, the origins of the molecular imprinting effect were studied using the newly developed Freundlich isotherm-affinity distribution (FIAD) analysis. The analysis is able to readily calculate an affinity distribution for MIPs from the limited analytical window. The FIAD analysis also yields an estimate of number, affinity, and heterogeneity for this subset of binding sites. Consistent with previous studies, MIPs were found to have higher capacities than the corresponding nonimprinted polymers (NIPs). Interestingly, MIPs were also found to be more heterogeneous than NIPs. Examination of variables in the imprinting process including temperature, template concentration, and cross-linking percentages further confirmed these trends. Based on these observations, a model for the imprinting effect was developed. The larger population of high-affinity sites in MIPs appears to arise from a broadening of the heterogeneous distribution. This suggests that noncovalent MIPs may be ill-suited for chromatographic applications and other applications that are detrimentally affected by binding site heterogeneity and better suited to applications that are less affected by heterogeneity such as sensing.