Benjamin S. Bleier

Effects of an LL-37-derived antimicrobial peptide in an animal model of biofilm Pseudomonas sinusitis

Background LL-37, an innate immunity protein expressed within sinonasal mucosa, has in vitro antibacterial and antifungal properties as well as efficacy against preformed Pseudomonas aeruginosa biofilms. We hypothesize that a 24 amino acid peptide derivative of LL-37 will show efficacy against biofilm-forming P. aeruginosa in an established animal model of sinusitis. Methods Five groups of six New Zealand rabbits were each infected with P. aeruginosa (PAO-1) and fitted with irrigating catheters 7 days later. Each group was instilled with either one of three different concentrations of peptide, a positive control of topical tobramycin, or the carrier solution without the peptide once a day for 10 days. Nasal diluent was collected throughout the irrigation period to assess for persistence or resolution of infection by determining colony-forming units (CFU). At study end, sinus mucosa was harvested for histological assessment of inflammation and SEM evaluation for ciliary integrity and presence of biofilms. Results Topical tobramycin at 400× minimum inhibitory concentration and 2.5 mg/mL of peptide were effective in significantly lowering CFUs after 10 days of irrigation. Histological evaluation showed increased signs of inflammation in a dose-dependent manner within mucosa and bone of the groups receiving the peptide. SEM analysis showed ciliary loss in a dose-dependent manner. Biofilms were present in all groups except for the highest concentration of peptide and tobramycin. Conclusion High concentrations of LL-37-derived peptide showed in vivo ability to eradicate Pseudomonas biofilms and decrease bacterial counts. However, increasing concentrations of peptide showed proinflammatory and ciliotoxic effects on sinus mucosa.

Vitamin D3 correlates inversely with systemic dendritic cell numbers and bone erosion in chronic rhinosinusitis with nasal polyps and allergic fungal rhinosinusitis

Vitamin D3 (VD3) is a steroid hormone that regulates bone health and numerous aspects of immune function and may play a role in respiratory health. We hypothesized that T helper type 2 (Th2) disorders, chronic rhinosinusitis with nasal polyps (CRSwNP) and allergic fungal rhinosinusitis (AFRS) would have VD3 deficiencies, resulting in increased mature dendritic cells (DCs) and bone erosion. We conducted a retrospective study examining VD3 levels in patients with AFRS (n = 14), CRSwNP (n = 9), chronic rhinosinusitis without nasal polyps (CRSsNP) (n = 20) and cerebrospinal fluid leak repair (non‐diseased controls) (n = 14) at time of surgery. Circulating immune cell levels were determined by immunostaining and flow cytometric analysis. Plasma VD3 and immune regulatory factors (granulocyte–macrophage colony‐stimulating factor and prostaglandin E2) were measured by enzyme‐linked immunosorbent assay. It was observed that CRSwNP and AFRS demonstrated increased circulating DCs, while chronic rhinosinusitis without nasal polyps displayed increased circulating macrophages. CRSwNP and AFRS were to found to have insufficient levels of VD3 which correlated inversely with circulating numbers of mature DCs, DC regulatory factors and bone erosion. CRSsNP displayed no change in circulating DC numbers or VD3 status compared to control, but did display increased numbers of circulating macrophages that was independent of VD3 status. Lastly, VD3 deficiency was associated with more severe bone erosion. Taken together, these results suggest support a role for VD3 as a key player in the immunopathology of CRSwNP and AFRS.

Current management of juvenile nasopharyngeal angiofibroma: a tertiary center experience 1999-2007.

Background Over the past 10 years, the management of juvenile nasopharyngeal angiofibroma (JNA) has been redefined because of the improvement of transnasal skull base techniques. However, the limits of endoscopic resection still have to be fully defined. The purpose of this study was to report on a series of patients presenting with JNA in an effort to further define an optimal treatment algorithm and improve outcomes. Methods A retrospective review was performed of 18 patients presenting to a tertiary care institution with JNA from 1999 to 2007. Patients were categorized by Andrews stage and data were collected on presentation, operative technique, and postoperative course. Results All patients underwent preoperative embolization. Stages 1, 2, and one 3a lesions were approached endoscopically while the remainder underwent open resection. In the endoscopic group the intraoperative blood loss was almost half that of the open group (506 versus 934 mL) and the average hospital stay was 1 day less (3 vs. 4 days). Conclusion Endoscopic resection is reasonable for Andrews stage 1, 2, and select 3a lesions and may allow for less bleeding and a shorter hospital stay. This study supports the current trend of expansion of indications for endoscopic JNA resection.

Increased presence of dendritic cells and dendritic cell chemokines in the sinus mucosa of chronic rhinosinusitis with nasal polyps and allergic fungal rhinosinusitis

The aim of this study was to determine if there is a link between local dendritic cells (DCs) and various subtypes of chronic rhinosinusitis (CRS): CRS with nasal polyposis (CRSwNP), CRS without nasal polyposis (CRSsNP), and allergic fungal rhinosinusitis (AFRS). Once DC presence was established we considered possible mechanisms for DC recruitment to the sinuses.

Mucocele rate after endoscopic skull base reconstruction using vascularized pedicled flaps.

Background Postoperative cerebrospinal fluid leak is a significant risk after endoscopic skull base surgery. Recently, novel reconstructive techniques using vascularized pedicled mucosal flaps have been applied to decrease this potential risk. Complete mucosal extirpation in the wound bed is not always feasible and the impact of insetting the flap over intact underlying mucosa is not clear. The purpose of this study was to determine the rate of mucocele formation after nasoseptal flap reconstruction without mucosal stripping. Methods This is an Institutional Review Board–approved, retrospective study consisting of 28 patients undergoing skull base reconstruction using a pedicled nasoseptal flap between 2008 and 2010 at a tertiary care hospital. In all cases the sinus or skull base mucosa surrounding the defect was left intact. Patients were followed postoperatively by endoscopy and/or imaging for evidence of mucocele formation in the reconstructive bed. Results The total rate of mucocele formation was 3.6% (1 of 28, noted on postoperative day 46). The mean follow-up time was 243 ± 174 days (range, 46–585 days). Eleven patients were followed for over 1 year. All flaps remained viable and well vascularized. Conclusion The pedicled nasoseptal flap is an effective means of reconstruction after endoscopic skull base surgery. Avoidance of extensive stripping of the surrounding mucosa does not result in a significant rate of postoperative mucocele formation in the short term. Long-term follow-up is still indicated.

Dysphagia after Chemoradiation: Analysis by Modified Barium Swallow

Objectives: We sought to describe the findings of modified barium swallow study after chemoradiation in patients with head and neck cancer and to correlate these findings with clinical variables, including gastrostomy tube dependence and clinical pneumonia. Methods: We retrospectively reviewed 49 patients at a tertiary care center who underwent modified barium swallow study for dysphagia after chemoradiation. Results: Patients with nonlaryngeal lesions had increased cricopharyngeal impairment (27.8% versus 0.0%; p = .04). Patients who underwent concomitant chemotherapy had increased epiglottic changes relative to those who had radiotherapy alone (66.7% versus 30.8%; p = .05). Clinical pneumonia developed in 31.9% of the patients, and 79.6% required gastrostomy tube placement for a mean duration of 18.1 months. Conclusions: Chemoradiation effects deglutition at multiple levels. A large percentage of patients will develop pneumonia and feeding tube dependence. This study is among the largest to correlate the results of modified barium swallow studies to clinical variables in this patient population. This study highlights the significant incidence of gastrostomy tube dependence and pneumonia in these patients.

The blood-brain barrier and nasal drug delivery to the central nervous system.

Background The blood-brain barrier (BBB) is a highly efficient system that separates the central nervous system (CNS) from general circulation and promotes selective transport of molecules that are essential for brain function. However, it also limits the distribution of systemically administered therapeutics to the brain; therefore, there is a restricted number of drugs available for the treatment of brain disorders. Several drug-targeting strategies have been developed to attempt to bypass the BBB, but none has proved sufficiently effective in reaching the brain. Methods The objective of this study is to generally review these strategies of drug administration to the CNS. Results Noninvasive methods of drug delivery, such as chemical and biologic transport systems, do not represent a feasible platform, whereas for most drugs, it is still not possible to achieve therapeutic levels within the brain tissue after intravenous or oral administration, and the use of higher potency or more concentrated doses may cause serious toxic side effects. Direct intrathecal drug delivery through a catheter into the CNS also presents several problems. Intranasal drug delivery is a potential alternative method due to the direct transport into the cerebrospinal fluid (CSF) compartment along the olfactory pathway, but the studys conclusions are controversial. An endoscopic intranasal surgical procedure using established skull base surgery reconstruction techniques based on the use of a nasal mucosa surgical flap as the only obstacle between the nose and the subarachnoid space has appeared as a potential solution to increase the absorption of intranasal drugs to the CNS. Conclusion Despite extensive efforts to develop new techniques to cross the BBB, none has proved sufficiently effective in reaching the brain, whereas minimizing adverse effects and the endoscopic mucosal grafting technique offers new potential promise.

Evolving materials and techniques for endoscopic sinus surgery.

Functional endoscopic sinus surgery was initially introduced as a minimally invasive procedure to treat chronic rhinosinusitis (CRS) in patients for whom medical management failed. Sinus surgery has been deemed an extremely effective part of the overall management of chronic sinus disease with symptomatic improvement in the vast majority of patients. At the forefront, technologic advances have been critical in advancing endoscopic sinus surgical procedures. With the introduction of improved optics and lighting, advanced instrumentation, and image-guided surgical navigation, the limitations of endoscopic procedures have been significantly reduced. Endoscopic techniques have evolved to include the management of both malignant and benign neoplasms of the sinuses and anterior skull base. This article highlights some of the newest advances in technology, materials, and medical/surgical techniques used in endoscopic sinus and skull base procedures and illustrates how they advance overall patient care to help minimize morbidity and complications.

In vivo laser tissue welding in the rabbit maxillary sinus.

Background One of the challenges in the current expansion of endoscopic sinonasal surgery is the ability to adequately reconstruct the skull base. Laser tissue welding (LTW) uses laser energy coupled to a biological solder to produce tissue bonds with burst thresholds exceeding human intracranial pressure. This technology could be used to reduce the rate of postoperative cerebrospinal fluid (CSF) leak. We performed this study to determine whether LTW can create durable tissue bonds in sinonasal mucosa that support normal wound healing and produce minimal collateral thermal injury. Methods Bilateral maxillary sinus mucosal incisions were made in 20 New Zealand white rabbits and one side was repaired using LTW. Burst pressure thresholds were measured on postoperative days 0, 5, and 15 and were compared with control using a two- way ANOVA and a post hoc Tukey test. Welds were examined histologically for thermal injury, inflammation, and fibroplasia and graded on a 4-point scale by three blinded observers. Results The burst pressures of the LTW group were significantly higher than control on postoperative day 0 (120.85 mm Hg, N = 4, SD = 47.84 versus 7.85 mm Hg, N = 4, SD = 0.78), and day 5 (132.56 mm Hg, N = 8, SD = 24.02 versus 41.7 mm Hg, N = 8, SD = 7.2; p < 0.05). By postoperative day 15 there was no significant difference between LTW (169.64 mm Hg, N = 8, SD = 18.49) and control (160.84 mm Hg, N = 8, SD = 14.16) burst thresholds. There was no evidence of thermal injury to the surrounding tissue in any group as well as no difference between experimental group and control with respect to inflammation or fibroplasia. Conclusion This is the first in vivo study showing that LTW is capable of producing tissue bonds exceeding human intracranial pressure with negligible thermal injury in sinonasal tissue. Welding can be performed endoscopically using a fiberoptic cable and may be useful in CSF leak and skull base repair.

Permeabilization of the blood-brain barrier via mucosal engrafting: implications for drug delivery to the brain.

Utilization of neuropharmaceuticals for central nervous system(CNS) disease is highly limited due to the blood-brain barrier(BBB) which restricts molecules larger than 500Da from reaching the CNS. The development of a reliable method to bypass the BBB would represent an enormous advance in neuropharmacology enabling the use of many potential disease modifying therapies. Previous attempts such as transcranial catheter implantation have proven to be temporary and associated with multiple complications. Here we describe a novel method of creating a semipermeable window in the BBB using purely autologous tissues to allow for high molecular weight(HMW) drug delivery to the CNS. This approach is inspired by recent advances in human endoscopic transnasal skull base surgical techniques and involves engrafting semipermeable nasal mucosa within a surgical defect in the BBB. The mucosal graft thereby creates a permanent transmucosal conduit for drugs to access the CNS. The main objective of this study was to develop a murine model of this technique and use it to evaluate transmucosal permeability for the purpose of direct drug delivery to the brain. Using this model we demonstrate that mucosal grafts allow for the transport of molecules up to 500 kDa directly to the brain in both a time and molecular weight dependent fashion. Markers up to 40 kDa were found within the striatum suggesting a potential role for this technique in the treatment of Parkinson’s disease. This proof of principle study demonstrates that mucosal engrafting represents the first permanent and stable method of bypassing the BBB thereby providing a pathway for HMW therapeutics directly into the CNS.