Endovascular Parent Vessel Occlusion Versus Flow Diversion in the Treatment of Large and Giant Aneurysms: A Randomized Comparison.

OBJECTIVE: Parent vessel occlusion (PVO) is a time-honored treatment for unclippable or uncoilable intracranial aneurysms. Flow diversion (FD) is a recent endovascular alternative that can occlude the aneurysm and spare the parent blood vessel. Our aim was to compare outcomes of FD with endovascular PVO. METHODS: This is a prespecified treatment subgroup analysis of the Flow diversion in Intracranial Aneurysms trial (FIAT). FIAT was an investigator-led parallel-group all-inclusive pragmatic randomized trial. For each patient, clinicians had to prespecify an alternative management option to FD before stratified randomization. We report all patients for whom PVO was selected as the best alternative treatment to FD. The primary outcome was a composite of core-lab determined angiographic occlusion or near-occlusion at 3-12 months combined with an independent clinical outcome (mRS<3). Primary analyses were intent-to-treat. There was no blinding. RESULTS: There were 45 patients (16.2% of the 278 FIAT patients randomized between 2011 and 2020 in 3 centers): 22 were randomly allocated to FD and 23 to PVO. Aneurysms were mainly large or giant (mean 22 mm) anterior circulation (mainly carotid) aneurysms. A poor primary outcome was reached in 11/22 FD (50.0%) compared to 9/23 PVO patients (39.1%) (RR: 1.28, 95% CI [0.66-2.47]; P = 0.466). Morbidity (mRS >2) at 1 year occurred in 4/22 FD and 6/23 PVO patients. Angiographic results and serious adverse events were similar. CONCLUSIONS: The comparison between PVO and FD was inconclusive. More randomized trials are needed to better determine the role of FD in large aneurysms eligible for PVO.

The RVU Compensation Model and Head and Neck Surgical Education.

BACKGROUND: The present study aims to quantify the opportunity cost of training residents and fellows for head and neck surgery. METHODS: A 2005-2015 review of ablative head and neck surgical procedures was performed using the National Surgical Quality Improvement Program (NSQIP). Work relative value units (wRVU) generated per hour were compared among procedures performed by attendings alone, attendings with residents, and attendings with fellows. RESULTS: Among 34,078 ablative procedures, the rate of wRVU generation per hour was greatest for attendings alone (10.3), followed by attendings with residents (8.9) and attendings with fellows (7.0, p < 0.001). Resident and fellow involvement was associated with opportunity costs of $60.44 per hour (95% CI: $50.21-$70.66/h) and $78.98 per hour ($63.10-$94.87/h, 95% CI), respectively. CONCLUSION: wRVU-based physician reimbursement does not consider or adjust for the extra effort involved in training future head and neck surgeons. LEVEL OF EVIDENCE: NA Laryngoscope, 134:113-119, 2024.

Management of Enlarging Tracheoesophageal Fistula with Voice Prosthesis in Laryngectomized Patients.

Management of Enlarging tracheoesophageal fistula (TEF) with Voice Prosthesis in Laryngectomized Head and Neck Cancer Patients. OBJECTIVES: An enlarging TEF following voice prosthesis placement impacts patient quality of life, risks airway compromise, and can lead to aspiration pneumonia. Pharyngoesophageal strictures have previously been reported to be associated with TEF enlargement and leakage. We describe a series of patients with enlarging TEFs after Tracheoesophageal puncture (TEP) for voice prosthesis who required pharyngoesophageal reconstruction. METHODS: Retrospective case series of laryngectomized H&N cancer patients with primary or secondary TEP who underwent surgical management for enlarging TEF site between 6/2016-11/2022. RESULTS: Eight patients were included. The mean age was 62.8 years old. Seven patients had a history of hypothyroidism. Of seven with prior H&N radiation history, two had both historical and adjuvant radiation. Two of the eight TEPs were placed secondarily. Mean time from TEP to enlarging TEF diagnosis was 891.3 days. Radial forearm-free flaps were used in five patients. Six had stenosis proximal to the TEF whereas one had distal stenosis and one had no evidence of stenosis. Mean length of stay was 12.3 days. Mean follow-up was 400.4 days. Two required a second free flap for persistent fistula. CONCLUSION: Surgical reconstruction of enlarging TEFs due to TEP/VP placement is effective in combination with addressing underlying pharyngeal/esophageal stenosis contributing to TEF enlargement and leakage. Radial forearm-free flaps have the additional benefit of a long vascular pedicle to access more distant and less-irradiated recipient vessels. Many fistulae are resolved after the first flap reconstruction, but some may require subsequent reconstruction in case of failure. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:198-206, 2024.

Adjuvant Radiotherapy in Moderately Advanced (T3) Oral Cavity Cancers.

OBJECTIVE: To investigate the impact of adjuvant radiotherapy in isolated locally advanced oral cavity cancers (pT3N0M0) without adverse features. METHODS: We selected all patients from the National Cancer Database (2004-2019) who underwent surgical treatment where the final pathology was T3N0M0 with negative margins. Demographics, details of treatment, and outcomes were abstracted. The impact of radiotherapy on survival was assessed with univariable, multivariable, and propensity score-matched analyses. RESULTS: We identified 571 patients in our survival cohort. Most were male (348, 60.9%), and median age was 65. Less than one-third (176, 30.8%) received adjuvant radiotherapy. The median length of follow-up was 29 months. Overall, adjuvant radiotherapy was associated with improved survival (87.2% vs. 77.7%, at 2 years, p < 0.01). On multivariable analysis controlling for age and comorbidities, this survival difference persisted (HR: 0.62, 95% CI: 0.43-0.90, p = 0.01). In a propensity score-matched population of 278 patients matched on age and comorbidities, adjuvant radiotherapy was still associated with longer survival (87.4% vs. 78.5%, p = 0.014). CONCLUSION: In our study, adjuvant radiotherapy was associated with improved survival in completely excised locally advanced oral cavity tumors (T3N0M0). However, a significant proportion of patients do not receive adjuvant radiotherapy. These findings highlight the need for continued efforts to promote guideline-recommended care. LEVEL OF EVIDENCE: 3 Laryngoscope, 134:2236-2242, 2024.

Force Profile as Surgeon-Specific Signature.

Objective: To investigate the notion that a surgeon's force profile can be the signature of their identity and performance. Summary background data: Surgeon performance in the operating room is an understudied topic. The advent of deep learning methods paired with a sensorized surgical device presents an opportunity to incorporate quantitative insight into surgical performance and processes. Using a device called the SmartForceps System and through automated analytics, we have previously reported surgeon force profile, surgical skill, and task classification. However, an investigation of whether an individual surgeon can be identified by surgical technique has yet to be studied. Methods: In this study, we investigate multiple neural network architectures to identify the surgeon associated with their time-series tool-tissue forces using bipolar forceps data. The surgeon associated with each 10-second window of force data was labeled, and the data were randomly split into 80% for model training and validation (10% validation) and 20% for testing. Data imbalance was mitigated through subsampling from more populated classes with a random size adjustment based on 0.1% of sample counts in the respective class. An exploratory analysis of force segments was performed to investigate underlying patterns differentiating individual surgical techniques. Results: In a dataset of 2819 ten-second time segments from 89 neurosurgical cases, the best-performing model achieved a micro-average area under the curve of 0.97, a testing F1-score of 0.82, a sensitivity of 82%, and a precision of 82%. This model was a time-series ResNet model to extract features from the time-series data followed by a linearized output into the XGBoost algorithm. Furthermore, we found that convolutional neural networks outperformed long short-term memory networks in performance and speed. Using a weighted average approach, an ensemble model was able to identify an expert surgeon with 83.8% accuracy using a validation dataset. Conclusions: Our results demonstrate that each surgeon has a unique force profile amenable to identification using deep learning methods. We anticipate our models will enable a quantitative framework to provide bespoke feedback to surgeons and to track their skill progression longitudinally. Furthermore, the ability to recognize individual surgeons introduces the mechanism of correlating outcome to surgeon performance.

Virtual Tumor Boards for Remote Learning in Head and Neck Surgical Oncology.

Importance: In addition to their patient management value, multidisciplinary tumor boards have been recognized as effective learning tools. However, the value of using a virtual tumor board as a learning tool for head and neck surgical oncology fellows has not been studied. Objective: To describe the structure and content of the American Head and Neck Society (AHNS) Virtual Tumor Board and assess its educational value as perceived by attendees. Design, Setting, and Participants: All sessions of the AHNS Virtual Tumor Board from April 8, 2020, to June 1, 2022, were reviewed. Topics, presenters, participants, and viewership data were collected as of October 15, 2022, from session recordings posted to an online video sharing and social media platform. Additionally, an anonymous, 14-question online survey was designed to elicit feedback from head and neck surgery trainees on virtual tumor board engagement, strengths, and weaknesses. The survey was electronically distributed in June and July 2022 to the 101 fellows enrolled in AHNS-accredited programs between July 1, 2020, and June 30, 2022. Main Outcomes and Measures: The primary aim was to tabulate online viewership of the sessions. The secondary aim was to qualitatively assess the experience of head and neck trainees with the AHNS Virtual Tumor Board using a survey. Results: Forty-two sessions of the virtual tumor board were held between April 8, 2020, and June 1, 2022. Almost all sessions (41 [98%]) were case based. One hundred and sixteen cases were presented, representing 2 to 3 cases per session, by 75 unique faculty members. Each session was viewed a mean of 217 times (range, 64-2216 views). In the 2021 to 2022 academic year, a mean of 60 viewers (range, 30-92 viewers) attended each live session. In all, 29 survey responses were collected from 101 fellows in AHNS-accredited programs (29% response rate). Most respondents felt the format allowed for excellent teaching (18 of 26 respondents [69%]) and discussion (19 of 26 respondents [73%]). Most respondents (22 of 29 respondents [76%]) believed that practicing head and neck surgeons would benefit from the sessions. Conclusions and Relevance: This survey study found that the AHNS Virtual Tumor Board was well-attended and well-reviewed by head and neck surgical oncology trainees. The virtual tumor board format could be used as model of remote learning for other organizations.

Delivery technology of inhaled therapy for asthma and COPD.

Inhaled therapy is the cornerstone of the management of asthma and chronic obstructive pulmonary disease (COPD). Drugs such as bronchodilators and corticosteroids are administered directly to the airways for local effect and rapid onset of action while systemic exposure and side effects are minimized. There are four major types of inhaler devices used clinically to generate aerosols for inhalation, namely, pressurized metered-dose inhalers (pMDIs), nebulizers, Soft Mist™ inhalers (SMIs) and dry powder inhalers (DPIs). Each of them has its own unique characteristics that can target different patient groups. For instance, patients' inhaler technique is critical for pMDIs and SMIs to achieve proper drug deposition in the lung, which could be challenging for some patients. Nebulizers are designed to deliver aerosols to patients during tidal breathing, but they require electricity to operate and are less portable than other devices. DPIs are the only device that delivers aerosols in dry powder form with better stability, but they rely on patients' inspiration effort for powder dispersion, rendering them unsuitable for patients with compromised lung function. Choosing a device that can cater for the need of individual patient is paramount for effective inhaled therapy. This chapter provides an overview of inhaled therapy for the management of asthma and COPD. The operation principles, merits and limitations of different delivery technologies are examined. Looking ahead, the challenges of delivering novel therapeutics such as biologics through the pulmonary route are also discussed.

Co-Delivery of D-LAK Antimicrobial Peptide and Capreomycin as Inhaled Powder Formulation to Combat Drug-Resistant Tuberculosis.

INTRODUCTION: The emergence of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) posed a severe challenge to tuberculosis (TB) management. The treatment of MDR-TB involves second-line anti-TB agents, most of which are injectable and highly toxic. Previous metabolomics study of the Mtb membrane revealed that two antimicrobial peptides, D-LAK120-A and D-LAK120-HP13, can potentiate the efficacy of capreomycin against mycobacteria. AIMS: As both capreomycin and peptides are not orally available, this study aimed to formulate combined formulations of capreomycin and D-LAK peptides as inhalable dry powder by spray drying. METHODS AND RESULTS: A total of 16 formulations were prepared with different levels of drug content and capreomycin to peptide ratios. A good production yield of over 60% (w/w) was achieved in most formulations. The co-spray dried particles exhibited spherical shape with a smooth surface and contained low residual moisture of below 2%. Both capreomycin and D-LAK peptides were enriched at the surface of the particles. The aerosol performance of the formulations was evaluated with Next Generation Impactor (NGI) coupled with Breezhaler®. While no significant difference was observed in terms of emitted fraction (EF) and fine particle fraction (FPF) among the different formulations, lowering the flow rate from 90 L/min to 60 L/min could reduce the impaction at the throat and improve the FPF to over 50%. CONCLUSIONS: Overall, this study showed the feasibility of producing co-spray dried formulation of capreomycin and antimicrobial peptides for pulmonary delivery. Future study on their antibacterial effect is warranted.

Surgical Treatment in Very Advanced (T4b) Adenoid Cystic Carcinoma of the Head and Neck.

OBJECTIVE: To compare treatment outcomes for T4b head and neck adenoid cystic carcinoma (ACC). STUDY DESIGN: Historical cohort study. SETTING: National Cancer Database (NCDB). METHODS: Identified all T4b ACC of head and neck origin diagnosed 2004 to 2019 in the NCDB. Demographics, clinical characteristics, treatment details, and survival were analyzed. Treatment outcomes were analyzed using univariable and multivariable Cox regression. RESULTS: We identified 606 cases of T4b ACC. Less than half (284, 47.0%) underwent curative-intent treatment. Among these, most were treated with primary surgery: surgery + radiotherapy (RT) (122, 43.0%) or surgery + chemoradiotherapy (CRT) (42, 14.8%). The positive margin rate was 78.7%, and 90-day postoperative mortality was zero. Nonsurgical patients were treated with definitive RT (60, 21.1%) or definitive CRT (60, 21.1%). The median follow-up was 51.5 months. Overall survival was 77.8% at 3 years. Three-year survival was higher for patients treated with surgery compared to those treated nonsurgically (84% vs 70%; p = .005). Surgical treatment remained associated with higher survival on multivariable analysis (hazard ratio [HR]: 0.47, p = .005). This effect was most pronounced for oral cavity tumors (HR: 0.17, p = .01). Among matched cohorts of surgically treated patients, there was no difference in 3-year survival between clinical T4a and T4b tumors (83.3% vs 83.0%, p = .99). CONCLUSION: Long-term survival for T4b ACC of the head and neck could be expected. Primary surgical treatments can be performed safely and are associated with longer survival. A carefully selected subset of patients with very advanced ACC might benefit from the consideration of surgical treatments.

Role of transoral robotic surgery in surgical treatment of early-stage supraglottic larynx carcinoma.

BACKGROUND: There are several options for primary surgical treatment of early-stage supraglottic squamous cell carcinoma (SCC), including transoral robotic surgery (TORS). The purpose of this study was to compare outcomes of TORS to open partial laryngectomy and transoral laser microsurgery (TLM). METHODS: Patients with clinical classification T1-2 supraglottic SCC diagnosed 2010-2019, treated with TORS, open partial laryngectomy, or TLM in the National Cancer Database were selected. RESULTS: One thousand six hundred three patients were included: 17% TORS, 26.5% TLM, 56.5% open. TORS patients had the lowest rates of adjuvant treatment (28.4% vs. TLM: 45.0%, open: 38.5%, p < 0.001), and lower positive margin rates than TLM (16.9% vs. 30.5%, p < 0.001). Thirty-day and ninety-day post-operative mortality did not differ between the approaches. Five-year survival was higher following TORS compared to open surgery (77.8% vs. 66.1%, p = 0.01); this difference persisted following matched-pair analysis. CONCLUSIONS: TORS may be a safe and effective surgical approach for early-stage supraglottic SCC in appropriate patients.

Inhalable neutralizing antibodies - promising approach to combating respiratory viral infections.

Monoclonal antibodies represent an exciting class of therapeutics against respiratory viral infections. Notwithstanding their specificity and affinity, the conventional parenteral administration is suboptimal in delivering antibodies for neutralizing activity in the airways due to the poor distribution of macromolecules to the respiratory tract. Inhaled therapy is a promising approach to overcome this hurdle in a noninvasive manner, while advances in antibody engineering have led to the development of unique antibody formats which exhibit properties desirable for inhalation. In this Opinion, we examine the major challenges surrounding the development of inhaled antibodies, identify knowledge gaps that need to be addressed and provide strategies from a drug delivery perspective to enhance the efficacy and safety of neutralizing antibodies against respiratory viral infections.

Adoption of adjuvant chemotherapy in high-risk salivary gland malignancies.

BACKGROUND: The present study characterizes national trends in the utilization of adjuvant chemotherapy to treat salivary gland malignancies. METHODS: The National Cancer Database was queried for salivary gland malignancies treated by surgery with radiation in 2004-2019. Proportions of patients receiving adjuvant chemotherapy over the study period were analyzed by linear regression. The impact of chemotherapy on overall survival was assessed using Kaplan-Meier and Cox proportional hazards analyses. RESULTS: Among 15 965 patients meeting inclusion criteria, 2355 (14.8%) received adjuvant chemotherapy. Chemotherapy utilization significantly increased from 4.9% to 16.5% over the study period (p < 0.001). No survival benefit was observed with adjuvant chemotherapy on propensity score-matched Kaplan-Meier analysis (HR: 0.98; 95% CI: 0.86-1.11; p = 0.72) or multivariable Cox regression (HR: 0.92; 95% CI: 0.78-1.09; p = 0.34). CONCLUSIONS: Adjuvant chemotherapy has been increasingly utilized to treat salivary gland malignancies in recent years. Our findings highlight the importance of obtaining high-quality prospective data regarding the benefit of chemotherapy.

Treatment of wide-necked bifurcation aneurysms with the eCLIPs device: 5-year experience of a single center.

BACKGROUND: The endovascular clip system (eCLIPs) is a novel device with both neck bridging and flow-diversion properties that make it suitable for the treatment of wide-necked bifurcation aneurysms. OBJECTIVE: To describe the clinical and radiologic outcomes of the eCLIPs device, including the first-in-man use of the latest version of the device. METHODS: This is a retrospective case series on all the wide-necked bifurcation aneurysms treated with the eCLIPs device in our center. The immediate and latest radiologic and clinical outcomes were assessed. RESULTS: The device was successfully implanted in 12 of 13 patients. After a median follow-up period of 19 months (range 3-64 months), all patients with available data (11/12) had a good radiologic outcome (modified Raymond-Roy classification scores of 1 or 2). Two patients (18.2%) underwent re-treatment with simple coiling through the device. One of these had a subarachnoid hemorrhage prior to re-treatment. There were no major complications (death or permanent neurologic deficits) associated with use of the device. CONCLUSION: Our series demonstrates occlusion rates that are similar to those of standard stent-assisted coiling and intrasaccular flow diversion for wide-necked bifurcation aneurysms. Larger registry-based studies are necessary to support our findings.

American Thyroid Association Guidelines and National Trends in Management of Papillary Thyroid Carcinoma.

Importance: Over time, the American Thyroid Association (ATA) guidelines have increasingly promoted more limited treatments for well-differentiated thyroid cancers. Objective: To determine whether the 2009 and 2015 ATA guidelines were associated with changes in the management of low-risk papillary thyroid carcinomas on a national scale. Design, Setting, and Participants: This historical cohort study used the National Cancer Database. All papillary thyroid carcinomas diagnosed from 2004 to 2019 in the National Cancer Database were selected. Patients with tumors of greater than 4 cm, metastases, or clinical evidence of nodal disease were excluded. Data were analyzed from August 1, 2021, to September 1, 2022. Main Outcomes and Measures: The primary aim was to tabulate changes in the rates of thyroid lobectomy (TL), total thyroidectomy (TT), and TT plus radioactive iodine (RAI) therapy after the 2009 and 2015 ATA guidelines. The secondary aim was to determine in which settings (eg, academic vs community) the practice patterns changed the most. Results: A total of 194 254 patients (155 796 [80.2%] female patients; median [range] age at diagnosis, 51 [18-90] years) who underwent treatment during the study period were identified. Among patients who underwent surgery, rates of TL decreased from 15.1% to 13.7% after the 2009 guidelines but subsequently increased to 22.9% after the 2015 changes. Among patients undergoing TT, rates of adjuvant RAI decreased from 48.7% to 37.1% after 2009 and to 19.3% after the 2015 guidelines. Trends were similar for subgroups based on sex and race and ethnicity. However, academic institutions saw larger increases in TL rates (14.9% to 25.7%) than community hospitals (16.3% to 19.5%). Additionally, greater increases in TL rates were observed for tumors 1 to 2 cm (6.8% to 18.9%) and 2 to 4 cm (6.6% to 16.0%) than tumors less than 1 cm (22.8% to 29.2%). Conclusions and Relevance: In this cohort study among patients with papillary thyroid carcinomas up to 4 cm, ATA guideline changes corresponded with increased TL and reduced adjuvant RAI. These changes were primarily seen in academic institutions, suggesting an opportunity to expand guideline-based care in the community setting.

Impact of frailty on 30-day death, stroke, or myocardial infarction in severe carotid stenosis: Endarterectomy versus stenting.

OBJECTIVE: Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are used for stroke prevention in patients with carotid stenosis. It remains unclear which surgical approach produces the best outcomes for elderly and frail patients. We investigated the impact of age and frailty on 30-day combined outcomes of death, stroke, and myocardial infarction (MI) in patients who received CEA or CAS for severe symptomatic carotid stenosis. METHODS: A retrospective analysis of the NSQIP database identified patients with severe carotid stenosis who received either CEA or CAS between 2015 and 2020 for study inclusion. Frailty was measured by the Modified Frailty Index 5-item (mFI-5), which stratified patients as non-frail (score=0), pre-frail (=1), frail (=2), or severely frail (=3). Age was subdivided into 65 years or younger, 66-84 years, and 85 years or older. The primary outcome was 30-day combined rates of death, stroke, and MI, as analyzed by multivariate logistic regression analyses, adjusted for sex, body mass index, smoking status, anesthetic type, and contralateral carotid stenosis. RESULTS: A total of 18,074 patients were included in analyses, of which 14,428 received CEA (80 %) and 3646 received CAS (20 %). Mean age was 70.8 and 70.5 years for CEA and CAS, respectively. The rate of combined outcome of death, stroke or MI at 30 days was significantly higher in CEA (3.3 %) than CAS (1.3 %) (χ2 =41.90, p < 0.001). Increasing frailty was associated with higher rates of the primary outcome in CEA patients (χ2 =30.26, p < 0.001) but not CAS (χ2 =6.95, p = 0.07). A 6-component risk score was constructed for the combined outcomes in CEA, which predicted adverse events with 80.7 % accuracy. CONCLUSIONS: Age and frailty have a significant impact on the risk of death, stroke, and MI at 30 days in patients with severe, symptomatic carotid stenosis who receive CEA, but not CAS. NON-STANDARD ABBREVIATIONS AND ACRONYMS: Body mass index (BMI), carotid artery stenting (CAS), carotid endarterectomy (CEA), current procedural technology (CPT), myocardial infarction (MI), modified Frailty Index 5-item (mFI-5), American College of Surgeons National Surgical Quality Improvement Program (NSQIP).

Sinonasal Glomangiopericytoma with Prolonged Postsurgical Follow-Up.

Sinonasal glomangiopericytoma is a rare vascular tumor of the respiratory epithelium. Treatment consists mainly of surgical resection, though there is no consensus regarding the use of adjuvant therapies or preoperative endovascular embolization. The postsurgical prognosis is favorable, though there is a high risk of delayed recurrence. Here, we present the case of a patient who underwent endoscopic resection of a sinonasal glomangiopericytoma and a review of the literature.

Sinonasal Undifferentiated Carcinoma with Failed Response to Induction Chemotherapy.

Sinonasal undifferentiated carcinoma (SNUC) is a rapidly growing malignancy with a propensity for extensive local invasion. Multimodal therapy, including surgery, radiotherapy, and chemotherapy, is the standard approach to treatment, but the optimal sequence and combination of these modalities are uncertain. Induction chemotherapy is being increasingly utilized based on recent reports that show better outcomes for patients who respond to chemotherapy and the ability to determine further course of treatment. We present a unique case of a patient with locally advanced SNUC that did not respond to induction chemotherapy and a review of the available literature relating to the management of this rare malignancy.

A dual action of D-amino acids on anti-biofilm activity and moisture-protection of inhalable ciprofloxacin powders.

Although inhalation powder aerosols of antibiotics have been used to treat respiratory infections caused by Pseudomonas aeruginosa, biofilms are difficult to clear. Ciprofloxacin and D-amino acids (D-Met, D-Trp and D-Phe) were shown to facilitate P. aeruginosa biofilm removal. Spray dried powders for inhalation tend to be amorphous, hence unstable to moisture which causes deterioration in the aerosol performance. Hydrophobic L-amino acids such as leucine can impart moisture protection. In this study, we hypothesized that co-spray dried formulations of ciprofloxacin and hydrophobic D-amino acids will offer the combined benefits of both anti-biofilm and moisture protection properties. Of the three D-amino acids tested, D-Met and D-Trp (at 5 mM) but not D-Phe reduced clinical isolate P. aeruginosa biofilm loads and the extent of biofilm clearance was further enhanced in the presence of ciprofloxacin. Subsequently, ciprofloxacin was spray dried alone or in combination with 30% (w/w) D-Met or D-Trp. The biological and physicochemical properties of the powders were assessed, including the minimum inhibitory concentration, anti-biofilm activity, particle size distribution and morphology, solid-state properties, water sorption, and aerosol performance. The spray dried combination powders were physically stable and inhalable with fine particle fraction (<5 µm) values of 50-57% when aerosolized. The powders exhibited enhanced anti-biofilm activity compared with ciprofloxacin alone. The presence of D-amino acids provided moisture protection, with the recrystallization event shifting from 50% RH to 80% RH in powders containing D-Trp. In conclusion, the use of D-amino acids (D-Met or D-Trp) is an attractive formulation strategy which offers dual benefits of anti-biofilm effect and moisture protection.

The effects of different doses of inhaled bacteriophage therapy for Pseudomonas aeruginosa pulmonary infections in mice.

OBJECTIVES: Inhaled phage therapy has been revisited as a potential treatment option for respiratory infections caused by multidrug-resistant Pseudomonas aeruginosa; however, there is a distinct gap in understanding the dose-response effect. The aim of this study was to investigate the dose-response effect of Pseudomonas-targeting phage PEV31 delivered by the pulmonary route in a mouse lung infection model. METHODS: Neutropenic BALB/c mice were infected with multidrug-resistant P. aeruginosa (2 × 104 colony-forming units) through the intratracheal route and then treated with PEV31 at three different doses of 7.5 × 104 (Group A), 5 × 106 (Group B), and 5 × 108 (Group C) plaque-forming units, or phosphate-buffered saline at 2 hours postinoculation. Mice (n = 5-7) were euthanized at 2 hours and 24 hours postinfection, and lungs, kidneys, spleen, liver, bronchoalveolar lavage fluid, and blood were collected for bacteria and phage enumeration. RESULTS: At 24 hours postinfection, all phage-treated groups exhibited a significant reduction in pulmonary bacterial load by 1.3-1.9 log10, independent of the delivered phage dose. The extent of phage replication was negatively correlated with the dose administered, with log10 titre increases of 6.2, 2.7, and 9 for Groups A, B, and C, respectively. Phage-resistant bacterial subpopulations in the lung homogenate samples harvested at 24 hours postinfection increased with the treatment dose (i.e. 30%, 74%, and 91% in respective Groups A-C). However, the mutants showed increased susceptibility to ciprofloxacin, impaired twitching motility, and reduced blue-green pigment production. The expression of the inflammatory cytokines (IL-1ß and IL-6, and TNF-α) was suppressed with increasing PEV31 treatment dose. DISCUSSION: This study provides the dose-response effect of inhaled phage therapy that may guide dose selection for treating P. aeruginosa respiratory infections in humans.