The mechanisms of action of metformin on head and neck cancer in the pre-clinical setting: a scoping review

This scoping review identifies the mechanistic pathways of metformin when used to treat head and neck cancer cells, in the pre-clinical setting. Understanding the underlying mechanisms will inform future experimental designs exploring metformin as a potential adjuvant for head and neck cancer. This scoping review was conducted according to the Joanna-Briggs Institute framework. A structured search identified 1288 studies, of which 52 studies fulfilled the eligibility screen. The studies are presented in themes addressing hallmarks of cancer. Most of the studies demonstrated encouraging anti-proliferative effects in vitro and reduced tumor weight and volume in animal models. However, a few studies have cautioned the use of metformin which supported cancer cell growth under certain conditions.

Sleep apnea multi-level surgery trial: long-term observational outcomes

STUDY OBJECTIVES

The sleep apnea multi-level surgery (SAMS) randomized clinical trial showed surgery improved outcomes at 6 months compared to ongoing medical management in patients with moderate or severe obstructive sleep apnea (OSA) who failed continuous positive airway pressure therapy. This study reports the long-term outcomes of the multi-level surgery as a case series.

METHODS

Surgical participants were reassessed >2 years postoperatively with the same outcomes reported in the main SAMS trial. Primary outcomes were apnea-hypopnea index (AHI) and Epworth sleepiness scale (ESS), with secondary outcomes including other polysomnography measures, symptoms, quality of life, and adverse events. Long-term effectiveness (baseline to long-term follow-up [LTFU]) and interval changes (6 month to LTFU) were assessed using mixed effects regression models. Control participants were also reassessed for rate of subsequent surgery and outcomes.

RESULTS

36/48 (75%) of surgical participants were reevaluated (mean (standard deviation)) 3.5 (1.0) years following surgery, with 29 undergoing polysomnography. AHI was 41/h (23) at preoperative baseline and 21/h (18) at follow-up, representing persistent improvement of -24/h (95% CI -32, -17; p < 0.001). ESS was 12.3 (3.5) at baseline and 5.5 (3.9) at follow-up, representing persistent improvement of -6.8 (95% CI -8.3, -5.4; p < 0.001). Secondary outcomes were improved long term, and adverse events were minor. Interval change analysis suggests stability of outcomes. 36/43 (84%) of the control participants were reevaluated, with 25 (69%) reporting subsequent surgery, with symptom and quality of life improvements.

CONCLUSION

Multi-level upper airway surgery improves OSA burden with long-term maintenance of treatment effect in adults with moderate or severe OSA in whom conventional therapy failed.

CLINICAL TRIAL

Multi-level airway surgery in patients with moderate-severe obstructive sleep apnea (OSA) who have failed medical management to assess change in OSA events and daytime sleepiness; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366019&isReview=true; ACTRN12614000338662.

Swallowing biomechanics in tracheostomised critically ill patients compared to age- and gender-matched healthy controls

Objective

The mechanistic effects of a tracheostomy on swallowing are unclear. Pharyngeal high-resolution manometry with impedance (P-HRM-I) is a novel swallow assessment tool providing quantifiable metrics. This study aimed to characterise swallowing biomechanics in tracheostomised critically ill (non-neurological) patients.

Design

Cohort study.

Setting

Australian tertiary hospital intensive care unit.

Participants

Tracheostomised adults, planned for decannulation.

Main outcome measures

Swallowing assessment using P-HRM-I, compared to healthy age- and gender-matched controls.

Results

In this tracheostomised cohort (n = 10), the Swallow Risk Index, a global measure of swallow function, was significantly elevated (p < 0.001). At the upper oesophageal sphincter (UOS), hypopharyngeal intrabolus pressure and UOS integrated relaxation pressure were significantly elevated (control 0.65 mmHg [-1.02, 2.33] v tracheostomy 13.7 mmHg [10.4, 16.9], P < 0.001; control -4.28 mmHg [-5.87, 2.69] v tracheostomy 12.2 mmHg [8.83, 15.6], P < 0.001, respectively). Furthermore, UOS opening extent and relaxation time were reduced (control 4.83 mS [4.60, 5.07] v tracheostomy 4.33 mS [3.97, 4.69], P = 0.002; control 0.52 s [0.49, 0.55] v tracheostomy 0.41 s [0.37, 0.45], P < 0.001, respectively). Total pharyngeal contractility (PhCI) measuring pharyngeal pressure generation was significantly elevated (control 199.5 mmHg cm.s [177.4, 221.6] v tracheostomy 326.5 mmHg cm.s [253.3, 399.7]; P = 0.001).

Conclusion

In a critically ill tracheostomised cohort, UOS dysfunction was the prevalent biomechanical feature, with elevated pharyngeal pressures. Pharyngeal weakness is not contributing to dysphagia in this cohort. Instead, elevated pharyngeal pressures may represent a compensatory mechanism to overcome the UOS dysfunction. Further studies to extend these findings may inform the development of timely and targeted rehabilitation.

BiZact™ tonsillectomy: Predictive factors for post-tonsillectomy haemorrhage from a 1717 case series

OBJECTIVE

To determine primary and secondary post-tonsillectomy haemorrhage (PTH) rates and identify predictive factors in a cohort of consecutive adult and paediatric BiZact™ tonsillectomy cases.

SETTING

Retrospective cohort study. Patients from Flinders Medical Centre, Noarlunga Hospital and private otolaryngology practices who underwent BiZact™ tonsillectomy from 2017 to 2020.

DATA COLLECTED

patient age, indication for tonsillectomy, surgeon experience, time and severity of PTH, including return to theatre. Each secondary PTH was graded using the Stammberger classification. Logistic regression was utilised to identify predictors of secondary PTH.

RESULTS

One thousand seven hundred and seventeen patient medical records were assessed (658 adults and 1059 children). The primary PTH rate was 0.1%, and secondary PTH rate was 5.9%. The majority of secondary PTH cases were Stammberger grade A (80/102, 78.4%) requiring observation only. Few secondary PTH required medical intervention (grade B; 9/102, 8.8%), return to theatre (grade C; 12/102, 11.8%), or blood transfusion (grade D; 1/102, 1.0%), with no death reported (grade E; 0/102, 0.0%). Recurrent secondary PTH occurred in 8 patients (0.5%). Predictive factors of secondary PTH in children were surgeon experience with trainees having greater chance of PTH (OR 2.502, 95% CI 1.345-4.654; p = .004) and age of child (OR 1.095, 95% CI 1.025-1.170; p = .007). Surgeon experience was a predictive factor for adults (OR 3.804, 95% CI 2.139-6.674; p < .001).

CONCLUSIONS

BiZact™ tonsillectomy has a low primary PTH rate, with a secondary PTH rate comparable to other 'hot tonsillectomy' techniques. The majority of PTH events were minor and self-reported. There appears to be a learning curve for trainee surgeons.

The Nasal Innate Immune Proteome After Saline Irrigation: A Pilot Study in Healthy Individuals

BACKGROUND

Previous research has shown diminished nasal immune function following nasal saline irrigation (NSI), returning to baseline at 6 hours. The aim of this study was to examine the immune nasal proteome before and after 14 days of nasal irrigation.

METHODS

Seventeen healthy volunteers received either isotonic (IsoSal) or low salt (LowNa) NSI. Nasal secretions were collected before and 30 min after NSI at baseline and again after 14 days. Specimens were analyzed using mass spectrometry to detect proteins of relevance to nasal immune function.

RESULTS

One thousand eight hundred and sixty-five proteins were identified with significant changes in 71 proteins, of which 23 were identified as part of the innate immune system. Baseline analysis demonstrated an increase of 9 innate proteins after NSI, most after IsoSal. After 14 days, a greater increase in innate peptides was present, with most now in the LowNa group. When NSI solutions were compared, a significant increase in 4 innate proteins, including a 211% in lysozyme, was detected in the LowNa group.

CONCLUSION

LowNa NSI demonstrates evidence of improving the innate immune secretions, especially lysozyme, in healthy volunteers.

Pharyngeal tongue base augmentation for dysphagia therapy: A prospective case series in patients post head and neck cancer treatment

BACKGROUND

Dysphagia post head and neck cancer (HNC) multimodality treatment is attributed to reduced pharyngeal strength. We hypothesized that pharyngeal tongue base augmentation for dysphagia (PAD therapy) would increase pharyngeal pressures during swallowing thereby improving swallow symptoms.

METHODS

Adults with moderate-severe dysphagia post-HNC treatment had PAD therapy using a temporary filler (hyaluronic acid [HA]), with follow-up long-lasting lipofilling. Swallowing preprocedure and postprocedure was assessed with the Sydney Swallow Questionnaire (SSQ), High-Resolution Pharyngeal Manometry (HRPM), and Videofluoroscopic Swallowing Study (VFSS). Statistical comparison utilized paired tests.

RESULTS

Six participants (all male; median age 64 years [IQR 56, 71]) underwent PAD therapy at a median of 47 [IQR 8, 95] months post-treatment. SSQ scores reduced from baseline (mean 1069 [95%CI 703, 1434]) to post-HA (mean 579 [76, 1081], p > 0.05), and post-lipofilling (491 [95%CI 913, 789], p = 0.003, n = 4). Individual participants demonstrated reduced Swallow Risk Index, Bolus Presence Time, and increased Upper Esophageal Sphincter opening, but mesopharyngeal contractile pressures were unchanged. VFSS measures of aspiration, residue, and severity were unchanged.

CONCLUSIONS

Novel PAD therapy is safe and improves dysphagia symptoms. Biomechanical swallowing changes are suggestive of more efficacious bolus propulsion with conservative filler volume, but this was unable to resolve residue or aspiration measures.

Volumetric MRI analysis of Multilevel Upper Airway Surgery effects on pharyngeal structure

STUDY OBJECTIVES

The Sleep Apnea Multilevel Surgery (SAMS) trial found that modified uvulopalatopharyngoplasty with tonsillectomy (if tonsils present) combined with radiofrequency tongue ablation reduced obstructive sleep apnea (OSA) severity and daytime sleepiness in moderate-severe OSA. This study aimed to investigate mechanisms of effect on Apnoea-Hypopnoea Index (AHI) reduction by assessing changes in upper airway volumes (airway space, soft palate, tongue, and intra-tongue fat).

METHODS

This is a case series analysis of forty-three participants of 51 randomized to the surgical arm of SAMS trial who underwent repeat magnetic resonance imaging (MRI). Upper airway volume, length, and cross-sectional area, soft palate and tongue volumes and tongue fat were measured. Relationships between changes in anatomical structures and apnea-hypopnea index (AHI) were assessed.

RESULTS

The participant sample was predominantly male (79%); mean ± SD age 42.7 ± 13.3 years, body mass index 30.8 ± 4.1 kg.m 2, and AHI 47.0 ± 22.3 events/hour. There were no, or minor, overall volumetric changes in the airway, soft palate, total tongue, or tongue fat volume. Post-surgery there was an increase in the minimum cross-sectional area by 0.1 cm 2 (95% confidence interval 0.04-0.2cm 2) in the pharyngeal airway, but not statistically significant on corrected analysis. There was no association with anatomical changes and AHI improvement.

CONCLUSIONS

This contemporary multi-level upper airway surgery has been shown to be an effective OSA treatment. The current anatomical investigation suggests there are not significant post-operative volumetric changes associated with OSA improvement six-months post-surgery. This suggests that effect on OSA improvement is achieved without notable deformation of airway volume. Reduced need for neuromuscular compensation during wake following anatomical improvement via surgery could explain lack of measurable volume change. Further research to understand the mechanisms of action of multilevel surgery is required.

Altered swallowing biomechanics in people with moderate-severe obstructive sleep apnea

STUDY OBJECTIVES

Dysphagia is a common but under-recognized complication of obstructive sleep apnea (OSA). However, the mechanisms remain poorly described. Accordingly, the aim of this study was to assess swallowing symptoms and use high-resolution pharyngeal manometry (HRPM) to quantify swallowing biomechanics in patients with moderate-severe OSA.

METHODS

Nineteen adults (4 female, mean age 46±26-68y) with moderate-severe OSA underwent HRPM testing with 5,10 & 20 ml volumes of thin and extremely thick liquids. Data were compared to 19 age- and sex-matched healthy controls (mean age 46±27-68y). Symptomatic dysphagia was assessed using the Sydney Swallow Questionnaire (SSQ). Swallow metrics were analyzed using the online application swallowgateway.com. General linear mixed model analysis was performed to investigate potential differences between people with moderate-severe OSA and controls. Data presented are means (95% CI).

RESULTS

26% (5/19) of the OSA group but none of the controls reported symptomatic dysphagia (SSQ>234). Compared to healthy controls, the OSA group had increased upper esophageal sphincter (UES) relaxation pressure (-2 [-1] vs. 2 [1]mmHg, F = 32.1, p <0.0001), reduced UES opening (6 vs. 5mS, F = 23.6, p<0.0001) and increased hypopharyngeal intrabolus pressure (2 [1] vs 7 [1]mmHg, F= 19.0, p <0.05). Additionally, upper pharyngeal pressures were higher, particularly at the velopharynx (88 [12] vs. 144 [12]mmHg.cm.s, F = 69.6, p<0.0001).

CONCLUSIONS

HRPM identified altered swallowing biomechanics in people with moderate-severe OSA, which is consistent with a subclinical presentation. Potential contributing mechanisms include UES dysfunction with associated upstream changes of increased hypopharyngeal distension pressure and velopharyngeal contractility.

Effect of Multilevel Upper Airway Surgery vs Medical Management on the Apnea-Hypopnea Index and Patient-Reported Daytime Sleepiness Among Patients With Moderate or Severe Obstructive Sleep Apnea: The SAMS Randomized Clinical Trial

IMPORTANCE

Many adults with obstructive sleep apnea (OSA) use device treatments inadequately and remain untreated.

OBJECTIVE

To determine whether combined palatal and tongue surgery to enlarge or stabilize the upper airway is an effective treatment for patients with OSA when conventional device treatment failed.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, parallel-group, open-label randomized clinical trial of upper airway surgery vs ongoing medical management. Adults with symptomatic moderate or severe OSA in whom conventional treatments had failed were enrolled between November 2014 and October 2017, with follow-up until August 2018.

INTERVENTIONS

Multilevel surgery (modified uvulopalatopharyngoplasty and minimally invasive tongue volume reduction; n = 51) or ongoing medical management (eg, advice on sleep positioning, weight loss; n = 51).

MAIN OUTCOMES AND MEASURES

Primary outcome measures were the apnea-hypopnea index (AHI; ie, the number of apnea and hypopnea events/h; 15-30 indicates moderate and >30 indicates severe OSA) and the Epworth Sleepiness Scale (ESS; range, 0-24; >10 indicates pathological sleepiness). Baseline-adjusted differences between groups at 6 months were assessed. Minimal clinically important differences are 15 events per hour for AHI and 2 units for ESS.

RESULTS

Among 102 participants who were randomized (mean [SD] age, 44.6 [12.8] years; 18 [18%] women), 91 (89%) completed the trial. The mean AHI was 47.9 at baseline and 20.8 at 6 months for the surgery group and 45.3 at baseline and 34.5 at 6 months for the medical management group (mean baseline-adjusted between-group difference at 6 mo, -17.6 events/h [95% CI, -26.8 to -8.4]; P < .001). The mean ESS was 12.4 at baseline and 5.3 at 6 months in the surgery group and 11.1 at baseline and 10.5 at 6 months in the medical management group (mean baseline-adjusted between-group difference at 6 mo, -6.7 [95% CI, -8.2 to -5.2]; P < .001). Two participants (4%) in the surgery group had serious adverse events (1 had a myocardial infarction on postoperative day 5 and 1 was hospitalized for observation following hematemesis of old blood).

CONCLUSIONS AND RELEVANCE

In this preliminary study of adults with moderate or severe OSA in whom conventional therapy had failed, combined palatal and tongue surgery, compared with medical management, reduced the number of apnea and hypopnea events and patient-reported sleepiness at 6 months. Further research is needed to confirm these findings in additional populations and to understand clinical utility, long-term efficacy, and safety of multilevel upper airway surgery for treatment of patients with OSA.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12614000338662.

Cross validated serum small extracellular vesicle microRNAs for the detection of oropharyngeal squamous cell carcinoma

BACKGROUND

Oropharyngeal squamous cell carcinoma (OPSCC) is often diagnosed at an advanced stage because the disease often causes minimal symptoms other than metastasis to neck lymph nodes. Better tools are required to assist with the early detection of OPSCC. MicroRNAs (miRNAs, miRs) are potential biomarkers for early head and neck squamous cell cancer diagnosis, prognosis, recurrence, and presence of metastatic disease. However, there is no widespread agreement on a panel of miRNAs with clinically meaningful utility for head and neck squamous cell cancers. This could be due to variations in the collection, storage, pre-processing, and isolation of RNA, but several reports have indicated that the selection and reproducibility of biomarkers has been widely affected by the methods used for data analysis. The primary analysis issues appear to be model overfitting and the incorrect application of statistical techniques. The purpose of this study was to develop a robust statistical approach to identify a miRNA signature that can distinguish controls and patients with inflammatory disease from patients with human papilloma virus positive (HPV +) OPSCC.

METHODS

Small extracellular vesicles were harvested from the serum of 20 control patients, 20 patients with gastroesophageal reflux disease (GORD), and 40 patients with locally advanced HPV + OPSCC. MicroRNAs were purified, and expression profiled on OpenArray™. A novel cross validation method, using lasso regression, was developed to stabilise selection of miRNAs for inclusion in a prediction model. The method, named StaVarSel (for Stable Variable Selection), was used to derive a diagnostic biomarker signature.

RESULTS

A standard cross validation approach was unable to produce a biomarker signature with good cross validated predictive capacity. In contrast, StaVarSel produced a regression model containing 11 miRNA ratios with potential clinical utility. Sample permutations indicated that the estimated cross validated prediction accuracy of the 11-miR-ratio model was not due to chance alone.

CONCLUSIONS

We developed a novel method, StaVarSel, that was able to identify a panel of miRNAs, present in small extracellular vesicles derived from blood serum, that robustly cross validated as a biomarker for the detection of HPV + OPSCC. This approach could be used to derive diagnostic biomarkers of other head and neck cancers.

Sleep Apnea Multilevel Surgery (SAMS) trial protocol: a multicenter randomized clinical trial of upper airway surgery for patients with obstructive sleep apnea who have failed continuous positive airway pressure

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is a serious and costly public health problem. The main medical treatment, continuous positive airway pressure, is efficacious when used, but poorly tolerated in up to 50% of patients. Upper airway reconstructive surgery is available when medical treatments fail but randomized trial evidence supporting its use is limited. This protocol details a randomized controlled trial designed to assess the clinical effectiveness, safety, and cost-effectiveness of a multilevel upper airway surgical procedure for OSA.

METHODS

A prospective, parallel-group, open label, randomized, controlled, multicenter clinical trial in adults with moderate or severe OSA who have failed or refused medical therapies. Six clinical sites in Australia randomly allocated participants in a 1:1 ratio to receive either an upper airway surgical procedure consisting of a modified uvulopalatopharyngoplasty and minimally invasive tongue volume reduction, or to continue with ongoing medical management, and followed them for 6 months.

RESULTS

Primary outcomes: difference between groups in baseline-adjusted 6 month OSA severity (apnea-hypopnea index) and subjective sleepiness (Epworth Sleepiness Scale). Secondary outcomes: other OSA symptoms (e.g. snoring and objective sleepiness), other polysomnography parameters (e.g. arousal index and 4% oxygen desaturation index), quality of life, 24 hr ambulatory blood pressure, adverse events, and adherence to ongoing medical therapies (medical group).

CONCLUSIONS

The Sleep Apnea Multilevel Surgery (SAMS) trial is of global public health importance for testing the effectiveness and safety of a multilevel surgical procedure for patients with OSA who have failed medical treatment.

CLINICAL TRIAL REGISTRATION

Multilevel airway surgery in patients with moderate-severe Obstructive Sleep Apnea (OSA) who have failed medical management to assess change in OSA events and daytime sleepiness. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366019&isReview=true Australian New Zealand Clinical Trials Registry ACTRN12614000338662, prospectively registered on 31 March 2014.

Long-term quality-of-life outcomes following treatment for adult obstructive sleep apnoea: comparison of upper airway surgery, continuous positive airway pressure and mandibular advancement splints

OBJECTIVE

Long-term quality-of-life (QOL) outcomes, complications and clinical effectiveness in patients undergoing treatment with upper airway surgery (UAS), continuous positive airway pressure (CPAP) and mandibular advancement splints (MAS) for adult obstructive sleep apnoea (OSA).

DESIGN

Retrospective cohort study.

SETTING

Multidisciplinary OSA clinic in University teaching hospital.

PARTICIPANTS

Consecutive, simultaneously treated patients with OSA undergoing UAS (n = 83), CPAP (n = 83) and MAS (n = 79).

MAIN OUTCOME MEASURES

Glasgow Benefit Inventory (GBI), Snoring Severity Scale (SSS), Epworth Sleepiness Score (ESS) and side-effects in all three groups were recorded at a mean of 34.5 months following start of treatment and compared via anova with Bonferroni's adjustment for pairwise comparisons.

RESULTS

Upper airway surgery demonstrated a statistically significant QOL benefit over MAS. All three groups showed a significant improvement in SSS with CPAP significantly better than MAS, but equivalent to UAS. Uncomplicated UAS provided a greater QOL outcome than compliant MAS, non-compliant CPAP (P < 0.05) and comparable to compliant CPAP. Patients undergoing UAS with recorded complications still reported equivalent QOL outcomes to compliant CPAP and MAS, suggesting these surgical complications are relatively minor compared to the QOL benefit of OSA treatment.

CONCLUSION

Upper airway surgery showed a significant improvement in QOL outcomes compared to non-compliant CPAP or MAS and equivalent benefit to compliant CPAP. This study strongly supports the role for contemporary UAS in OSA when CPAP is not or no longer an option.

Comparing surgical experience with performance on a sinus surgery simulator

BACKGROUND

This study evaluates whether surgical experience influences technical competence using the Flinders sinus surgery simulator, a virtual environment designed to teach nasal endoscopic surgical skills.

METHODS

Ten experienced sinus surgeons (five consultants and five registrars) and 14 novices (seven resident medical officers and seven interns/medical students) completed three simulation tasks using haptic controllers. Task 1 required navigation of the sinuses and identification of six anatomical landmarks, Task 2 required removal of unhealthy tissue while preserving healthy tissue and Task 3 entailed backbiting within pre-set lines on the uncinate process and microdebriding tissue between the cuts.

RESULTS

Novices were compared with experts on a range of measures, using Mann-Whitney U -tests. Novices took longer on all tasks (Task 1: 278%, P < 0.005; Task 2: 112%, P < 0.005; Task 3: 72%, P < 0.005). In Task 1, novices' instruments travelled further than experts' (379%, P < 0.005), and provided greater maximum force (12%, P < 0.05). In Tasks 2 and 3 novices performed more cutting movements to remove the tissue (Task 2: 1500%, P < 0.005; Task 3: 72%, P < 0.005). Experts also completed more of Task 3 (66%, P < 0.05).

CONCLUSIONS

The study demonstrated the Flinders sinus simulator's construct validity, differentiating between experts and novices with respect to procedure time, instrument distance travelled and number of cutting motions to complete the task.

The effect of nasal irrigation formulation on the antimicrobial activity of nasal secretions

BACKGROUND

Saline-based irrigation solutions are evidence-based rhinological treatments; however, the formulation of these solutions could theoretically alter the function of innate antimicrobial peptides. The aim of this study was to determine if the antimicrobial activity of normal human nasal secretions in vivo is altered by commercially available large volume irrigation solutions.

METHODS

Minimally manipulated sinonasal secretions were collected from patients with chronic rhinosinusitis (CRS; n = 10) and normal healthy volunteers (n = 20). In a subset of control patients (n = 10) secretions were collected prior to, and at 1 hour, 6 hours, and 24 hours after nasal irrigation with 4 commercial irrigation solutions. Lysozyme and lactoferrin levels were analyzed and the antimicrobial activity of secretions determined using a radial diffusion assay.

RESULTS

The antimicrobial activity of nasal secretions was reduced in CRS patients compared to healthy volunteers (p < 0.01), but there was no significant difference in antimicrobial peptide concentrations. Isotonic nasal irrigation reduced lysozyme and lactoferrin levels, which returned to baseline levels by 6 hours; in addition to a sustained decrease in antimicrobial activity before returning to baseline at 24 hours. Low-salt solution stimulated peptide secretion by approximately 40% at 6 hours and 24 hours, but produced a transient decrease in antimicrobial activity, returning to baseline levels by 6 hours. Hypertonic solution initially decreased lysozyme and lactoferrin levels but maintained baseline levels of antimicrobial activity and increased peptide secretion by approximately 30% at 24 hours.

CONCLUSION

The formulation of nasal irrigation solutions significantly affects the measured levels and functionality of sinonasal antimicrobial peptides.

A double-blind randomized controlled trial of normal saline, lactated Ringer's, and hypertonic saline nasal irrigation solution after endoscopic sinus surgery

BACKGROUND

Nasal douching is commonly performed after endoscopic sinus surgery (ESS). There is a lack of studies comparing the clinical effect of various douching solutions after ESS. This study investigated the clinical effects of normal saline, lactated Ringer's, and hypertonic saline nasal douching solutions after ESS.

METHODS

Adult patients (41.8 ± 12.9 years) undergoing bilateral ESS for chronic rhinosinusitis at a single tertiary referral center were blindly randomized to one of the three study solutions and reviewed on postoperative weeks 1, 3, and 6. The 20-item Sino-Nasal Outcome Test (SNOT-20) scores, visual analog scale (VAS) symptom scores, digital video capture of the sinus cavities, and mucociliary clearance (MCC) times were performed at each visit. The mucosa appearances were scored by a second investigator, blinded to the douching solution.

RESULTS

Seventy-four patients were recruited. All groups showed an improvement with treatment in SNOT-20 scores and VAS scores, as well as endoscopic evaluation of mucosa appearance over time. There was no improvement of MCC during the treatment period. Irrigation with lactated Ringer's solution resulted in better symptom scores in SNOT-20 (p < 0.05) and VAS (p < 0.05), compared with irrigation with normal saline or hypertonic saline solutions. Patients receiving hypertonic saline solutions had less polypoidal mucosa at week 6.

CONCLUSION

Douching with lactated Ringer's solution after ESS results in better improvement in sinonasal symptoms, compared with normal saline or hypertonic saline solutions.

Fungicidal activity of lysozyme is inhibited in vitro by commercial sinus irrigation solutions

BACKGROUND

Lysozyme is an innate immune peptide with bactericidal and fungicidal activity (FA). Despite increased expression of lysozyme protein in chronic rhinosinusitis (CRS) sinus mucosa, CRS patients experience repeated bacterial and/or fungal infections. Commercial sinus irrigation solutions are often used to provide symptomatic relief. However, one of the mechanisms of action of lysozyme involves ionic interactions with the microbial cell wall, which may be inhibited by ionic solutions such as commercial sinus irrigation solutions.

OBJECTIVE

Determine if the FA of lysozyme is reduced in the presence of solutions with increasing ionic strength and inhibited in the presence of commercial sinus irrigation solutions.

METHODS

Using an in vitro colony-forming unit (CFU) assay, the FA of lysozyme (5 μM) was tested against a fungi commonly isolated from CRS patients, Aspergillus fumigatus, in solutions of increasing ionic strength or commercial sinus irrigation solutions. FA was presented as percent of control.

RESULTS

FA of lysozyme against A. fumigatus was 95% in a 21-mM ionic strength solution. However, with increasing ionic strength, FA decreased and was abolished in a 46-mM ionic strength solution. Commercial sinus irrigation solutions abolished the FA of lysozyme against A. fumigatus.

CONCLUSION

The in vitro FA of lysozyme is dependent on the ionic strength of the solution. The use of sinus irrigation solutions should be further evaluated with regard to maintaining functional activity of cationic antimicrobial peptides involved in sinonasal innate immunity.

Submucosal Lingualplasty for Adult Obstructive Sleep Apnea

Objective

To measure quality-of-life outcomes, polysomnographic outcomes, and adverse effects for a new technique of tongue reduction in obstructive sleep apnea.

Study Design

Case series.

Setting

Tertiary hospital.

Subjects and Methods

Consecutively treated adult patients (N = 27) with obstructive sleep apnea having submucosal lingualplasty in 2007 were studied. All had concurrent or previous uvulopalatoplasty ± palatal advancement. Full polysomnography preoperatively and 3.7 ± 0.4 months postoperatively, scored using the American Academy of Sleep Medicine 2007 criteria, was recorded. Snoring severity score, Epworth Sleepiness Scale, and complication data were collected at a 2.61 ± 0.08-year follow-up via questionnaire.

Results

Mean snoring severity score fell from 7.1 ± 0.4 to 2.3 ± 0.6 ( P < .05). Epworth Sleepiness Scale score fell from 8.3 ± 1.1 to 5.8 ± 1.0 ( P < .05). The apnea-hypopnea index (AHI) fell from 44.0 ± 4.3 to 12.5 ± 2.3 ( P < .05). Success, defined as achieving an AHI <15 postoperatively, was observed in 74% (20/27), with each of these patients achieving a reduction in AHI >50%. Lowest oxygen saturation improved from 84 ± 1 to 88 ± 1 ( P < .05). Pain was mild to moderate. Short-term postoperative complications included bleeding (3.7%) and infection (14.8%). Some minor long-term (6 months) alteration in tongue function was reported with regard to speech (47%), swallow (33%), and taste (33%).

Conclusion

Submucosal lingualplasty with concurrent palatal surgery is a promising treatment option in adult patients with obstructive sleep apnea with macroglossia.

Lysozyme expression is increased in the sinus mucosa of patients with chronic rhinosinusitis

BACKGROUND

The presence of fungi and bacteria in the paranasal sinuses may contribute to ongoing inflammation. Lysozyme is an innate immune peptide with bactericidal and fungicidal activity. The expression of lysozyme in chronic rhinosinusitis (CRS) is poorly understood and deficiencies in lysozyme expression may contribute to the ongoing inflammation in CRS patients.

OBJECTIVE

Determine lysozyme expression in sinus mucosa of normal and CRS patients with (CRSwNP) and without (CRSsNP) nasal polyps.

METHODOLOGY

Sinus mucosa specimens (n = 82) were processed for standard histology, immunohistochemical localisation of lysozyme, immunofluorescent localisation of fungi, and qPCR analysis of lysozyme expression.

RESULTS

CRS specimens displayed high-levels of lysozyme immunoreactivity in many of the abundant serous cells. Moderate levels were detected in some epithelial cells and inflammatory cells. Low levels were detected in some subepithelial glands of control specimens. No difference in immunoreactivity was detected between CRSwNP and CRSsNP specimens. Fungal elements were not visualised in any sinus specimen. qPCR analysis demonstrated variable lysozyme expression between individuals.

CONCLUSIONS

Lysozyme protein expression is increased in patients with CRS, suggesting a defect in lysozyme expression is not responsible for the microbial colonisation often associated with CRS. The functional activity of lysozyme in CRS patients needs to be further investigated.

Absence of Helicobacter pylori in pediatric adenoid hyperplasia

OBJECTIVES

To (1) develop a reverse transcription-polymerase chain reaction assay to determine whether Helicobacter pylori and/or other members of the Helicobacteraceae family are detected in hyperplastic adenoids of children and (2) critically analyze published polymerase chain reaction methods to ascertain whether false-positive detection of H pylori has been reported.

DESIGN

Cohort study.

PATIENTS

Adenoid biopsy specimens (78 hyperplastic and 15 normal) were collected from children aged 2 to 10 years.

METHODS

Total RNA was extracted before reverse transcription of bacterial RNA using Helicobacteraceae-specific primer. A nested reverse transcription-polymerase chain reaction protocol was designed to detect all species of the Helicobacteraceae family. A piece of each biopsy specimen was examined histologically.

RESULTS

Laryngopharyngeal reflux was suspected in 41% of the children (n = 23) on the basis of the Reflux Symptom Index. No evidence of H pylori was found in any adenoid sample. Candidatus Wolinella africanus was the only Helicobacteraceae family member detected in 1 hyperplastic adenoid. Histologic examination identified very few bacterial organisms. Previous polymerase chain reaction findings may be the result of false-positive H pylori detection.

CONCLUSIONS

Inflammation and enlargement of the adenoids is not likely due to ongoing bacterial infection arising from laryngopharyngeal reflux. We conclude that H pylori and other Helicobacteraceae family members are not major contributors to the development of hyperplastic adenoids in children.

Human lysozyme has fungicidal activity against nasal fungi

BACKGROUND

The cationic antimicrobial peptide lysozyme is the most prevalent innate immune protein in nasal secretions but there is a paucity of research regarding its role in paranasal sinus disease. Lysozyme is generally regarded as an antibacterial agent; however, some data suggest activity toward yeast. This study was designed to determine if lysozyme displays fungicidal activity toward fungi commonly identified in patients with chronic rhinosinusitis (CRS) or fungal sinusitis.

METHODS

Using a colony-forming unit assay the fungicidal activity of lysozyme (0, 0.5, 5, and 50 micromolar; 0- to 7-hour treatment) was tested against strains of Aspergillus fumigatus, the yeast Candida albicans, and other fungi commonly identified in mucin of patients with CRS. Fungi cultured directly from the mucin of two CRS patients were also tested to determine if they were resistant to the fungicidal activity of lysozyme.

RESULTS

The fungicidal effect of lysozyme was both concentration and time dependent. After 7-hour treatment lysozyme (5 micromolar) had >80% fungicidal activity against A. fumigatus, Penicillium sp., Acremonium sp., C. albicans, and Candida parapsilosis. The fungicidal activity of lysozyme toward Alternaria alternata could not be determined. Lysozyme was also fungicidal toward the clinical isolates A. fumigatus and Aspergillus terreus cultured from the mucin of CRS patients.

CONCLUSION

Lysozyme displays fungicidal activity toward many fungi commonly identified in patients with CRS, as well as clinical fungi isolates cultured from the mucin of CRS patients. Additional studies are required to determine the regulation of lysozyme in CRS.

Galanin inhibits caerulein-stimulated pancreatic amylase secretion via cholinergic nerves and insulin

Pancreatic exocrine secretion is affected by galanin, but the mechanisms involved are unclear. We aimed to determine the effect and elucidate the mechanism of action of exogenous galanin on basal and stimulated pancreatic amylase secretion in vitro. The effect of galanin on basal-, carbachol-, and caerulein-stimulated amylase secretion from isolated murine pancreatic lobules was measured. Carbachol and caerulein concentration-response relationships were established. Lobules were coincubated with galanin (10(-12) M to 10(-7) M), carbachol (10(-6) M), or caerulein (10(-10) M). Lobules were preincubated with atropine (10(-5) M), tetrodotoxin (10(-5) M), hexamethonium (10(-5) M), or diazoxide (10(-7) M and 10(-4) M) for 30 min followed by incubation with caerulein (10(-10) M) alone or combined with galanin (10(-12) M). Amylase secretion was expressed as percent of total lobular amylase. Immunohistochemical studies used the antigen retrieval technique and antisera for galanin receptor (GALR) 1, 2, and 3. Carbachol and caerulein stimulated amylase secretion in a concentration-dependent manner with maximal responses of two- and 1.7-fold over control evoked at 10(-6) M and 10(-10) M, respectively. Galanin (10(-12) M) completely inhibited caerulein-stimulated amylase secretion but had no effect on carbachol-stimulated or basal secretion. Atropine and tetrodotoxin pretreatment abolished the caerulein-stimulated amylase secretion, whereas hexamethonium had no significant effect. Diazoxide significantly reduced caerulein-stimulated amylase secretion by approximately 80%. Galanin did not affect caerulein-stimulated amylase secretion in the presence of hexamethonium or diazoxide. Glucose-stimulated amylase secretion was also inhibited by galanin. Immunohistochemistry revealed islet cells labeled for GALR2. These data suggest that galanin may modulate caerulein-stimulated amylase secretion by acting on cholinergic nerves and/or islet cells possibly via GALR2 to regulate insulin release.

A novel preparation to study rat pancreatic spinal and vagal mechanosensitive afferents in vitro

The management of pancreatic pain is a significant clinical problem so understanding of how sensory signals are generated in pancreatic tissue is fundamental. We aimed to characterize mechanosensitive and chemosensitive properties of pancreatic spinal and vagal afferents in vitro. Spinal and vagal afferent preparations from Sprague-Dawley rats were established incorporating the left splanchnic nerve or vagus nerves respectively. The common bile duct was cannulated for distension of the pancreatic duct with fluid. Nerve discharge evoked by blunt probing, duct distension or electrical stimulation was obtained from teased nerve bundles using standard extra-cellular recording. Discharge from 197 spinal afferent bundles was recorded, of which 57% displayed spontaneous activity. Blunt probing revealed 61 mechanosensitive receptive fields which were associated primarily with arteries/blood vessels (33/61) and the parenchyma (22/61). All mechanosensitive responses were slowly adapting, with 33% continuing to discharge after termination of the stimulus and 60% displaying a response threshold <10 g. Application of chemical mediators (bradykinin, histamine, 5-hydroxytryptamine, cholecystokinin octapeptide) evoked a response from 31/57 units, with 33% excitatory and 23% inhibitory. Spontaneous discharge was recorded from 72% of 135 vagal bundles. Mechanosensitive receptive fields were not identified in the pancreas but were evident in adjacent organs. No spinal or vagal afferent response to duct distension was obtained. In conclusion, pancreatic mechanosensitive spinal afferents are common, in contrast to pancreatic mechanosensitive vagal afferents indicating that pancreatic sensory innervation is predominantly spinal. Chemosensitive spinal afferent nerve endings are present in the pancreas and respond to a variety of inflammatory and physiological mediators.

The tripeptide analog feG ameliorates severity of acute pancreatitis in a caerulein mouse model

Acute pancreatitis (AP) is associated with significant morbidity and mortality; however, there is no specific treatment for this disease. A novel salivary tripeptide analog, feG, reduces inflammation in several different animal models of inflammation. The aims of this study were to determine whether feG reduced the severity of AP and modifies the expression of pancreatic ICAM-1 mRNA during AP in a mouse model. AP was induced in mice by hourly (x12) intraperitoneal injections of caerulein. A single dose of feG (100 microg/kg) was coadministered with caerulein either at time 0 h (prophylactic) or 3 h after AP induction (therapeutic). Plasma amylase and pancreatic MPO activities and pancreatic ICAM-1 mRNA expression (by RT-PCR) were measured. Pancreatic sections were histologically assessed for abnormal acinar cells and interstitial space. AP induction produced a sevenfold increase in plasma amylase, a tenfold increase in pancreatic MPO activity, and a threefold increase in interstitial space, and 90% of the acinar cells were abnormal. Prophylactic treatment with feG reduced the AP-induced plasma amylase activity by 45%, pancreatic MPO by 80%, the proportion of abnormal acinar cells by 30%, and interstitial space by 40%. Therapeutic treatment with feG significantly reduced the AP-induced abnormal acinar cells by 10% and the interstitial space by 20%. Pancreatic ICAM-1 mRNA expression was upregulated in AP and was reduced by 50% with prophylactic and therapeutic treatment with feG. We conclude that feG ameliorates experimental AP acting at least in part by modulating ICAM-1 expression in the pancreas.

Neurohormonal regulation of the sphincter of Oddi

The control of sphincter of Oddi (SO) motor activity is complex and involves interactions between the SO smooth muscle with nerves, bioactive agents, and presumably interstitial cells of Cajal. Disturbances in SO motility are known to be related to painful clinical conditions, such as SO dysfunction and acute pancreatitis. Understanding normal SO motility and comparing this to disturbed SO motility patterns may identify mechanisms that could be targeted for future pharmacologic intervention. The effect on SO motility of recently identified neurotransmitters/neuropeptides, such as purines and orexins, is currently being determined. Furthermore, because the control of SO motility is complex, investigations with known bioactive agents, such as cholecystokinin and nitric oxide, are continuing. This review summarizes research investigating SO motility and function performed in 2005 and 2006.

Selective iNOS inhibition enhances spontaneous gallbladder motility in the Australian possum

Gallbladder inflammation is a common and painful disease. Inducible nitric oxide synthase (iNOS) plays a major role in inflammatory diseases, and iNOS inhibitors are being developed as therapeutic agents. Reports are inconsistent regarding iNOS expression in normal gallbladder. The aim of this study was to determine the effect of iNOS inhibition on spontaneous gallbladder motility. mRNA extracted from normal possum gallbladders was analysed by PCR. Gallbladder contractility was evaluated using a highly selective iNOS inhibitor AR-C102222AA (AR-C) in in vitro muscle strips (0.1-10 000 microm) and in vivo (0.1-30 micromol kg(-1)) experiments. Gene expression analysis revealed the presence of iNOS mRNA in normal gallbladder (n = 3). In vitro, AR-C (0.1-1000 micromol L(-1)) produced a concentration-dependent increase in spontaneous gallbladder contractile activity and basal tension (P < 0.05; n = 6). The maximum effect was a 1.8-fold increase in activity and 2.1-fold increase in basal tension. Pretreatment of muscle strips with tetrodotoxin (1 micromol L(-1)) did not block the AR-C-induced response (n = 5). In vivo, AR-C (30 micromol kg(-1), i.v.) increased gallbladder contraction frequency (P < 0.05; n = 8). These data suggest that iNOS is continually expressed in the normal gallbladder, which presumably releases low levels of nitric oxide and in turn may modulate spontaneous gallbladder motility. AR-C may be a beneficial treatment for patients suffering from acute cholecystitis.

Exogenous purines induce differential responses in the proximal and distal regions of the possum sphincter of Oddi

1. The aim of this study was to compare the effect of exogenous ATP and adenosine on spontaneous motility of the proximal and distal regions of the possum sphincter of Oddi (SO). 2. ATP or adenosine (1 microm-1 mm) was applied to distal-SO or proximal-SO muscle rings in organ baths in the absence or presence of tetrodotoxin (TTX) or P1/P2 antagonists. 3. Both ATP and adenosine altered spontaneous activity, predominantly in proximal-SO rings. 4. Exogenous ATP induced a bi-phasic response consisting of a brief TTX-sensitive excitatory component, and a longer-lasting TTX-insensitive inhibitory component. 5. The excitatory ATP response likely involves P2X receptors, whereas the late inhibitory response likely involves P2Y receptors. 6. Exogenous adenosine decreased spontaneous SO activity, via a TTX-insensitive mechanism. 7. Exogenous purines modulate SO motility, acting primarily in the proximal region of the SO, via neural and non-neural mechanisms and multiple purine receptor subtypes.

Exogenous adenosine triphosphate and adenosine stimulate proximal sphincter of oddi motility via neural mechanisms in the anesthetized Australian possum

We aimed to determine if exogenous adenosine triphosphate or adenosine modulated sphincter of Oddi motility and involved neural mechanisms. Sphincter of Oddi motility was recorded in anesthetized possums by manometry. Adenosine triphosphate or adenosine (1 microM-10 mM) was applied topically to the sphincter before and after pretreatment with tetrodotoxin, hexamethonium, atropine, or Nomega-nitro-L-arginine methyl ester. Sphincter contraction amplitude and frequency were quantified. Adenosine triphosphate induced a concentration-dependent increase in proximal sphincter contraction amplitude and frequency (P < 0.05). This response was reduced by tetrodotoxin and atropine but enhanced by hexamethonium and Nomega-nitro-L-arginine methyl ester. Adenosine concentration dependently increased proximal sphincter contraction amplitude (P < 0.05) only. This response was reduced by tetrodotoxin, atropine, and Nomega-nitro-L-arginine methyl ester, whereas hexamethonium had no effect. We conclude that exogenous adenosine triphosphate and adenosine stimulate proximal sphincter of Oddi motility via neural mechanisms, involving cholinergic motor neurons. Adenosine triphosphate may further modulate sphincter motility via nicotinic and nitrergic pathways.

Pancreatobiliary afferent recordings in the anaesthetised Australian possum

The sensory innervation to the pancreatobiliary system is poorly characterized. Afferent signals from the gastrointestinal tract and biliary tree are transmitted to the central nervous system via the vagus and spinal nerves. We aimed to record afferent discharge in order to characterize the vagal and splanchnic afferent signals from the possum upper gastrointestinal tract, biliary tree and pancreas. In 21 anaesthetised possums nerve fibres were teased from the vagus or splanchnic nerve for multi-unit recording. Mechanical stimuli consisted of balloon distension of the gallbladder and duodenum (2-7 ml) and fluid distension (0-20 mm Hg) of the bile or pancreatic ducts. Approximately 60% of fibres from all nerves displayed spontaneous discharge. Spinal afferent responses to mechanical stimuli were infrequent (n=13). Increased discharge occurred in response to duodenal (12/99 fibres) or gallbladder (7/96 fibres) distension, but not to bile duct (0/73 fibres) or pancreatic duct (0/51 fibres) distension. Vagal afferent responses to distension of the duodenum or stomach (5-30 ml) were more common (n=8). Increased discharge was recorded in response to duodenal (49/134 fibres), or gastric (22/70 fibres) distension. Responses to gallbladder distension were less frequent (6/99 fibres) and as with the spinal afferent no response to bile duct (0/66) or pancreatic duct (0/70) distension were recorded. We conclude that mechanosensitive afferents in the pancreatobiliary system are relatively rare, particularly within the ducts, and/or that they are adapted to monitor stimuli other than luminal distension.

The sphincter of Oddi: understanding its control and function

The most common functional disorders of the biliary tract and pancreas are associated with disordered motility of the sphincter of Oddi (SO). The SO is a neuromuscular structure located at the junction of the bile and pancreatic ducts with the duodenum. The primary functions of the SO are to regulate the delivery of bile and pancreatic juice into the duodenum, and to prevent the reflux of duodenal contents into the biliary and pancreatic systems. Disordered motility of the SO leads to the common and painful clinical conditions of SO dysfunction and acute pancreatitis. In order to understand normal SO motility, studies have been performed addressing SO function, control of spontaneous SO activity, responses to bioactive agents, SO innervation, and reflexes with other gastrointestinal organs. These studies have led to the current understanding of how the SO functions and may permit the development of targeted therapy for SO dysfunction and acute pancreatitis. This review summarizes the current knowledge regarding the control and regulation of SO motility, highlighting laboratory based and clinical research performed over the last 5 years.

Highly selective iNOS inhibition and sphincter of Oddi motility in the Australian possum

AIM

Inducible nitric oxide synthase (iNOS) plays a major role in acute pancreatitis. Selective inhibitors of iNOS are being developed as therapeutic agents. Sphincter of Oddi (SO) dysfunction may cause pancreatitis and nitric oxide is necessary for SO relaxation. A new highly selective iNOS inhibitor, AR-C102222AA (AR-C), is evaluated together with the established iNOS inhibitor, L-N(6)-(1-iminoethyl)lysine (L-NIL), and the selective neuronal nitric oxide synthase (nNOS) blocker S-methyl-l-thiocitrulline (SMTC).

METHODS

In anaesthetized Australian Brush-tailed possums, the effect of topical, i.v. or i.a. administration of these drugs was evaluated on spontaneous SO motility, blood pressure (BP) and pancreatic vascular perfusion. SO motility was recorded by manometry and pancreatic vascular perfusion by laser Doppler fluxmetry. Also, the effect of SMTC and AR-C on electrical field stimulation (EFS)-induced non-cholinergic non-adrenergic (NANC) SO relaxation in vitro was evaluated.

RESULTS

Infusion of AR-C (0.1-30 micromol kg(-1)) increased SO contraction frequency (P = 0.026) only at the two highest doses. L-NIL infusion (0.15 to 14.7 micromol kg(-1)) also increased SO contraction frequency at 8.8 micromol kg(-1) (P < 0.05) and reduced SO contraction amplitude at the two highest doses (P < 0.05). SMTC injections (0.5 nmol-2.4 micromol) produced a dose-dependent increase in SO contraction frequency (P = 0.009), but no effect was seen on the other parameters. In vitro SMTC (40-400 microm) inhibited EFS-induced NANC relaxation in a dose-dependent manner (P < 0.0005). In contrast AR-C (10-500 microm) had no effect on EFS-induced NANC relaxation (P > 0.05).

CONCLUSIONS

At low doses, AR-C does not effect SO motility or EFS-induced NO mediated relaxation. However, high doses of AR-C and L-NIL in vivo influenced SO motility by inhibiting nNOS activity and these effects need be considered in relation to therapeutic doses of this agent.

The possum sphincter of Oddi pumps or resists flow depending on common bile duct pressure: a multilumen manometry study

The sphincter of Oddi (SO) regulates trans-sphincteric flow (TSF) by acting primarily as a pump or as a resistor in specific species. We used the Australian possum SO, which functions similarly to the human SO, to characterize SO motility responses to different common bile duct (CBD) and duodenal pressures. Possum CBD, SO and attached duodenum (n= 18) was mounted in an organ bath. External reservoirs were used to impose CBD (0-17 mmHg) and duodenal (0, 4, 7 mmHg) pressure. Spontaneous SO activity was recorded using four-lumen pico-manometry and TSF was measured gravimetrically. Temporal analysis of manometric and TSF recordings identified three functionally distinct biliary-SO regions, the proximal-SO (juxta-CBD), body-SO and papilla-SO. At CBD pressures < 3 mmHg the motor activity of these regions was coordinated to pump fluid. Proximal-SO contractions isolated fluid within the body-SO. Peristaltic contraction through the body-SO pumped this fluid through the papilla-SO (17-27 microl contraction), which opened to facilitate flow. CBD pressure > 3.5 mmHg resulted in progressive changes in TSF to predominantly passive 'resistor'-type flow, occurring during proximal-SO-body-SO quiescence, when CBD pressure exceeded the pressure at the papilla-SO. Progression from pump to resistor function commenced when CBD pressure was 2-4 mmHg greater than duodenal pressure. These results imply that TSF is dependent on the CBD-duodenal pressure difference. The papilla-SO is pivotal to TSF, relaxing during proximal-SO-body-SO pumping and closing during proximal-SO-body-SO quiescence. The pump function promotes TSF at low CBD pressure and prevents bile stasis. At higher CBD pressure, the papilla-SO permits TSF along a pressure gradient, thereby maintaining a low pressure within the biliary tract.

Endogenous endothelin increases gallbladder tone and leads to acute cholecystitis in the Australian possum

Endothelins are bioactive peptides produced by gallbladder epithelial cells. We aimed to determine the role of endothelins in acute cholecystitis. Escherichia coli lipopolysaccharide vs saline (sham) was instilled into the gallbladder lumen of Australian possums. Some animals received the non-selective endothelin antagonist, tezosentan. At 4 or 24 h, plasma and gallbladder endothelins and white blood cell count (WBCC) were determined. Acute cholecystitis was assessed using a histopathology score. In other animals gallbladder tone was determined. At 4h, a dose-dependent 60-fold increase in gallbladder endothelin level occurred (P = 0.001) but other parameters remained comparable with sham animals. Epithelial cells were endothelin-immunoreactive. At 24 h, the WBCC rose (P < 0.007), and severe cholecystitis developed. Gallbladder but not plasma endothelin levels remained elevated. Tezosentan pre-treatment resulted in a histologically normal gallbladder, but the WBCC and gallbladder endothelin levels were elevated. Lipopolysaccharide or saline instillation also caused a time-dependent increase in gallbladder tone over 4 h (P < 0.001), but not in control animals. This increase was reduced by tezosentan treatment. Gallbladder endothelin production is an early event in acute cholecystitis, increases gallbladder tone and plays a crucial role in the inflammatory process.

A2A and A3 receptors mediate the adenosine-induced relaxation in spontaneously active possum duodenum in vitro

1. The aim of this study was to define the P1 purinergic receptors that regulate spontaneous or adenosine-induced duodenal motor activity. 2. Spontaneous contractile activity was recorded isometrically from possum longitudinal duodenal muscle strips. Adenosine (0.5 micro M-1 mM) was administered noncumulatively and repeated after pretreatment with a P1 antagonist or tetrodotoxin (TTX, 1 micro M), (n=4-7). Antagonists used were: A(1), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 10 nM); A(2A), 8-(3-chlorostyryl)caffeine (CSC, 10 micro M); A(2B), 3-isobutyl-8-pyrrolidinoxanthine (IPDX, 10 micro M); A(3), 9-chloro-2-(2-furanyl)-5-[(phenylacetyl) amino][1,2,4]-triazolo(1,5-c)quinazoline (MRS1220, 10 micro M). Changes in activity are expressed as percentage of baseline. Statistical analysis utilised nonparametric tests. 3. Adenosine (n=34) induced a long-lasting, concentration-dependent decrease in activity by 55.6+/-3.2% area under curve (AUC), 47.3+/-4.0% contraction amplitude, 31.6+/-3.6% basal tension and 10.4+/-1.7% contraction frequency (all P<0.001). The adenosine-induced decrease in contraction amplitude was blocked by CSC (P<0.01) or inhibited by MRS1220 (P<0.03) pretreatment, but not modified by TTX, DPCPX or IPDX pretreatment. 4. Adenosine antagonists modified spontaneous contractile activity. Pretreatment with DPCPX or CSC increased basal tension, whereas IPDX or MRS1220 pretreatment decreased contractile activity. 5. In conclusion, exogenous adenosine reduced duodenal longitudinal motor activity via A(2A) and A(3) receptors. Our findings suggest that endogenous purines may modulate spontaneous duodenal motor activity.

Effects of bioactive agents on biliary motor function

Our understanding of biliary motility under normal and pathophysiologic conditions is still incomplete, but there have been recent advances. Of particular interest are the mechanisms involved in gallbladder filling and emptying, with a focus on understanding the processes underlying impaired gallbladder emptying leading to gallbladder dyskinesia and the formation of gallstones or cholecystitis. The sphincter of Oddi (SO) is a complex neuromuscular structure. Recent studies have attempted to unravel the specific neural or hormonal mechanisms operating under normal physiologic conditions and those that may lead to SO dysfunction. Furthermore, new research fronts are emerging, including the role of leptin in obese patients with impaired biliary motility and the action of electroacupuncture for possible treatment of SO dysfunction. This review illustrates the broad front of current research regarding the effects of bioactive agents on biliary motility, including enteric hormones, nitric oxide, opioids, inflammatory mediators, leptin, protease inhibitors, neurotransmitters, and electroacupuncture.

Liquid dose pulmonary instillation of gentamicin PulmoSpheres formulations: tissue distribution and pharmacokinetics in rabbits

PURPOSE

To assess the pharmacokinetics and biodistribution of gentamicin, delivered as PulmoSpheres formulations in rabbit serum and lung tissue following intratracheal instillation in a perflubron vehicle.

METHODS

Rabbits were anesthetized, intubated, and mechanically ventilated with O2 (FiO2 = 0.50). Animals were then given 5 mg/kg gentamicin either intravenously, intramuscularly (TM), or intratracheally (IT) gentamicin PulmoSpheres formulation, instilled in 1.8 ml/kg of liquid perflubron vehicle. Serum and lung lobe sections were collected at multiple time points and assayed for gentamicin content.

RESULTS

Serum gentamicin levels peaked at 64.7 microg/ml, 11.2 microg/ml, and 5.0 microg/ml following intravenous, TM, and IT administration, respectively. Absolute bioavailabilitv at 8 h for IM administration was 76.8% and 57.0% when delivered IT. Although peak lung levels of drug were reached within 1 h, total lung gentamicin concentration after IT administration was more than two orders of magnitude greater than that achieved following TM administration (680,540 vs. 4,985 microg min, respectively) with significant levels of the antibiotic remaining in the lung even after 1 week.

CONCLUSIONS

High levels of gentamicin in lung tissue can be achieved by instillation of a gentamicin PulmoSpheres formulation in a perflubron vehicle, termed liquid dose installation, without reaching toxic systemic levels allowing for increased local delivery of agents such as gentamicin at the site of the infection.

Receptor-mediated targeting of spray-dried lipid particles coformulated with immunoglobulin and loaded with a prototype vaccine

PURPOSE

Spray-dried lipid-based microparticles (SDLM) serve as a platform for delivery of a wide variety of compounds including peptides, proteins, and vaccines to the respiratory mucosa. In the present study, we assessed the impact of IgG-mediated targeting to phagocytic cells of inactivated influenza virus formulated in SDLM, on subsequent immune responses.

METHODS

SDLM were produced containing inactivated influenza virus strain A/WSN/32/H1N1 (WSN), with or without IgG. Using phagocytic antigen presenting cells (APC) and a T cell hybridoma (TcH) line specific for a dominant influenza virus epitope, we compared the in vitro responses elicited by ligand-formulated (SDLM-IgG-WSN) and non-ligand particles (SDLM-WSN). The effect of including the IgG ligand in the formulation was further characterized by measuring the immune responses of rodents vaccinated with SDLM.

RESULTS

SDLM-IgG-WSN were internalized in an Fc receptor (FcR)-dependent manner by phagocytic APC that were then able to effectively present a dominant, class II-restricted epitope to specific T cells. While SDLM-WSN elicited a lower response than administration of plain inactivated virus in saline, the level of the T cell response was restored both in vitro and in vivo by incorporating the APC FcR ligand, IgG, in the SDLM.

CONCLUSIONS

Incorporation of FcR ligand (IgG) in SDLM restored the limited ability of formulated virus to elicit T-cell immunity, by receptor-mediated targeting to phagocytes.

Relationship between amine-carboxyboranes and TNF alpha for the regulation of cell growth in different tumor cell lines

The amine-carboxyboranes were shown to be synergistic with tumor necrosis factor alpha (TNF alpha) in cytotoxicity and inhibition of DNA synthesis in select types of cancer cells depending on the presence of a TNF alpha high affinity receptor on the membrane of the cell. Initially both TNF alpha and the amine-carboxyboranes reduce the influx of calcium but later cause a significant increase intracellularly. This influx is not linked with the amine-carboxyborane activating the calcitonin receptor in the tumor cells. Neither the agents nor TNF alpha directly inhibits DNA topoisomerase II activity but both did cause decreased phosphorylation of the enzyme by protein kinase C (PKC). The two agents caused synergistic inhibition. This event correlated with increased DNA protein linked breaks, DNA fragmentation and cell death. These protein linked breaks are additive with etoposide's effects but the latter agent's mechanism is different than phosphorylation of topoisomerase II. There was no evidence that the DNA fragmentation was caused by a calcium induced endonuclease enzyme in these cancer cells. The low-molecular weight amine-carboxyboranes appear to play an identical function as TNF alpha in its role to cause DNA breaks and fragmentation to cause apoptosis.

Effects of diaspirin cross-linked hemoglobin on motor function of the duodenum and biliary system in the Australian brush-tailed possum in vivo

Chemically altered hemoglobin-based oxygen carriers have been developed as prototype blood substitutes. Such molecules may affect numerous biological processes, since free hemoglobin scavenges nitric oxide (NO). Diaspirin cross-linked hemoglobin (DCLHb) is a chemically cross-linked molecule, which has a pressor effect on blood pressure, mainly mediated by NO scavenging. However, the effects of DCLHb on the gastrointestinal and biliary motility have not been reported. This study was conducted to investigate the effects of DCLHb on the duodenal and biliary motility and determine if the underlying mechanism involves a NO pathway. Blood pressure, duodenal, sphincter of Oddi and gallbladder motility and trans-sphincteric flow were recorded in anesthetized Australian Brush-tailed possums. The effects of intravenously administered DCLHb (10% solution) or oncotically matched human serum albumin (HSA) solution on these parameters were investigated. To determine the involvement of a NO-mediated pathway in these effects, animals were pretreated with N(omega)-nitro-L-arginine methyl ester (L-NAME) before DCLHb or HSA was given. DCLHb increased blood pressure and duodenal contraction frequency and slowed trans-sphincteric flow compared with the HSA control. The effects of DCLHb on blood pressure and trans-sphincteric flow were immediate and transient, whereas the effect on duodenal contraction frequency was delayed and long-lived. Pretreatment with L-NAME alone increased blood pressure and duodenal contraction frequency and slowed trans-sphincteric flow. DCLHb-induced changes were not evident in the presence of L-NAME. These findings suggest that DCLHb affects duodenal and trans-sphincteric flow predominantly by NO scavenging.

Randomized safety studies of intravenous perflubron emulsion. I. Effects on coagulation function in healthy volunteers

Previous perfluorocarbon (PFC) emulsions have been associated with transient adverse events (i.e., platelet activation, decreased platelet count, febrile responses, changes in hemodynamic function). The Phase I studies described in this report were parallel, randomized, double-blinded, placebo-controlled studies conducted in 48 healthy volunteers (n = 24 per study) with perflubron emulsion (Oxygent; Alliance Pharmaceutical Corp., San Diego, CA). Because of the decreased platelet counts observed with previous PFC emulsions and the intended use of perflubron emulsion in surgical patients, these studies assessed postdosing coagulation responses and hemostasis. PFC pharmacokinetic variables were also evaluated. The primary endpoint for examination of coagulation effects was prospectively defined as bleeding time. Subjects received either saline (3 mL/kg) control, or perflubron emulsion at 1.2 g PFC/kg or 1.8 g PFC/kg, and were evaluated for a 14-day period. No postinfusion changes in bleeding time or differences in ex vivo agonist-induced platelet aggregation were observed. A 17% reduction in platelet count was observed 3 days after dosing in the 1.8-g PFC/kg group; levels recovered to baseline by Day 7. The intravascular half-life of perflubron for the first 24 h was dose dependent: 9.4+/-2.2 h and 6.1+/-1.9 h in the 1.8- and 1.2-g PFC/kg groups, respectively. Results indicate that this perflubron emulsion did not affect coagulation function in healthy volunteers.

Sphincter of Oddi dysfunction produces acute pancreatitis in the possum

BACKGROUND

Sphincter of Oddi dysfunction has been implicated as a cause of various forms of acute pancreatitis. However, there is no direct evidence to show that sphincter of Oddi dysfunction can cause obstruction of trans-sphincteric flow resulting in acute pancreatitis.

AIMS

To determine if induced sphincter of Oddi spasm can produce trans-sphincteric obstruction and, in combination with stimulated pancreatic secretion, induce acute pancreatitis.

METHODS

In anaesthetised possums, the pancreatic duct was ligated and pancreatic exocrine secretion stimulated by cholecystokinin octapeptide/secretin to induce acute pancreatitis. In separate animals, carbachol was applied topically to the sphincter of Oddi to cause transient sphincter obstruction. Sphincter of Oddi motility, trans-sphincteric flow, pancreatic duct pressure, pancreatic exocrine secretion, plasma amylase levels, and pancreatic tissue damage (histology score) were studied and compared with variables in ligation models.

RESULTS

Acute pancreatitis developed following stimulation of pancreatic exocrine secretion with peptides after pancreatic duct ligation (p<0.05). Neither pancreatic duct ligation nor stimulation of pancreatic exocrine secretion with cholecystokinin octapeptide/secretin alone resulted in acute pancreatitis. Topical carbachol stimulated sphincter of Oddi motility abolished trans-sphincteric flow, and increased pancreatic exocrine secretion (p<0.05) and pancreatic duct pressure to levels comparable with pancreatic duct ligation (p<0.001). Carbachol application (with or without combined peptide stimulation) elevated plasma amylase levels (p<0.01) and produced pancreatic tissue damage (p<0.05). Decompression of pancreatic duct ameliorated these effects (p<0.05).

CONCLUSION

Induced sphincter of Oddi dysfunction when coupled with stimulated pancreatic secretion causes acute pancreatitis. This may be an important pathophysiological mechanism causing various forms of acute pancreatitis.

Randomized safety studies of intravenous perflubron emulsion. II. Effects on immune function in healthy volunteers

Particle size distribution is a major determinant of particle clearance by the mononuclear phagocytic system and the potential for concomitant activation of resident macrophages. To test the safety of a second-generation perflubron-based emulsion (60% perfluorocarbon [PFC] wt/vol; Oxygent [Alliance Pharmaceutical Corp., San Diego, CA]) with a small mean particle size, two parallel, randomized, double-blinded, placebo-controlled studies were conducted in 48 healthy volunteers (n = 24 per study). The study described herein focuses on safety concerning immune function. The primary endpoint was defined prospectively as delayed hypersensitivity skin test responses with lymphocyte proliferative responses to mitogenic stimulation providing a secondary measure for changes in cell-mediated immunity. Subjects received either perflubron emulsion IV (1.2 g PFC/kg or 1.8 g PFC/kg) or saline (3 mL/kg) control. Perflubron emulsion had no effect on delayed hypersensitivity skin reactions, lymphocyte proliferative potential, circulating immunoglobulins, complement activation, or plasma levels of the inflammatory cytokines, tumor necrosis factor-alpha, interleukin-1 alpha, and interleukin-1 beta. Perflubron emulsion was generally well tolerated, although there was a dose-dependent increase in minor flu-like symptoms in the perflubron treatment groups at 24 h after dosing. Increased serum levels of interleukin-6 were observed in those subjects exhibiting febrile responses. The clinical safety profile of perflubron emulsion supports its continued investigation as a temporary oxygen carrier in surgical patients to reduce exposure to allogeneic blood transfusion.

Proximal and distal segments of the possum sphincter of Oddi respond differently to neural and cholecystokinin octapeptide stimulation in vitro

BACKGROUND/AIMS

Previous studies have demonstrated separate pancreatic duct (PD) and bile duct (BD) components of the sphincter of Oddi (SO) and suggested distinct proximal and distal functional segments. This study was designed to determine if proximal and distal segments of the BD component of the SO (BD-SO) and PD component of the SO (PD-SO) responded equally to (1) activation of SO-duodenal neural pathways, and (2) exogenous cholecystokinin octapeptide (CCK-8).

METHODS

Intact SO-duodenum preparations from Australian brush-tailed possums (n = 6) were mounted in organ baths. SO activity was recorded from the proximal and distal segments of BD-SO and PD-SO +/- electrical activation of duodenal nerves at two separate sites. Full thickness muscle strips from the proximal and distal segments of the BD-SO and PD-SO were prepared (n = 8), mounted in organ baths, and exposed to CCK-8 (10(-9)- 10(-6) M), +/- tetrodotoxin.

RESULTS

Activation of duodenal nerves evoked different responses in some segments of the BD-SO and PD-SO, depending on the site of duodenal electrical stimulation. CCK-8 induced a concentration-dependent, tetrodotoxin-insensitive decrease in the contraction amplitude of SO muscle strips from the proximal but not the distal SO. BD-SO and PD-SO strips were not different.

CONCLUSIONS

The SO is composed of BD and PD components each of which contains proximal and distal segments that can respond independently to appropriate stimuli.

Perflubron attenuates neutrophil adhesion to activated endothelial cells in vitro

Infiltration of activated neutrophils into the lung appears to be a key element in the severe lung injury that develops in animal models of acute lung injury. Partial liquid ventilation with perflubron has been shown to ameliorate tissue damage compared with conventional mechanical ventilation in acute lung injury models. Pilot experiments indicated that indirect exposure to perflubron could modulate the degree to which subsequent neutrophil binding to endothelial cell monolayers was upregulated after lipopolysaccharide activation. Endothelial cell monolayers preexposed to perflubron showed >40% reductions in the surface steady-state levels of E-selectin and intercellular adhesion molecule-1 achieved after proinflammatory activation (P < 0.05), which correlated with a reduction in the real-time association constants measured by biosensor techniques. These results indicate that direct contact with the perflubron liquid phase is not necessary to attenuate inflammatory responses. Rather, diffusion of perflubron from the alveolar space into the adjacent pulmonary vascular endothelial layer may modulate neutrophil adhesion and thereby reduce the rate of infiltration of activated neutrophils into the injured lung.

In vitro cellular effects of perfluorochemicals correlate with their lipid solubility

Preclinical studies comparing perflubron partial liquid ventilation with conventional mechanical ventilation have indicated that perflubron partial liquid ventilation may exert some anti-inflammatory effects. To assess whether these effects were related to the lipid solubility properties of perflubron rather than to nonspecific biophysical properties of the perfluorocarbon (PFC) liquid phase, we studied the effects of PFCs with varying lipid solubilities on the platelet aggregation response to various procoagulants and the erythrocyte hemolytic response to osmotic stress. In both cases, the degree of the response was directly related to the lipid solubility of the PFC. All the perflubron content of erythrocytes was found to be associated with the membrane compartment. The time to reach a maximum effect on hemolysis with perflubron was relatively slow (2-4 h), which paralleled the time for perflubron to accumulate in erythrocyte membranes. The rate and extent of perflubron partitioning into lecithin liposomes were similar to those of erythrocyte membranes, supporting the hypothesis that perflubron was partitioning into the lipid component of the membranes. Thus some of the potential modulatory effects of perflubron on excessive inflammatory responses that occur during acute lung injury and acute respiratory distress syndrome may be influenced in part by the extent of PFC partitioning into the lipid bilayers of cellular membranes.

Novel lipid-based hollow-porous microparticles as a platform for immunoglobulin delivery to the respiratory tract

PURPOSE

Delivery of specific antibodies or immunoglobulin constructs to the respiratory tract may be useful for prophylaxis or active treatment of local or systemic disorders. Therefore, we evaluated the utility of lipid-based hollow-porous microparticles (PulmoSpheres) as a potential delivery vehicle for immunoglobulins.

METHODS

Lipid-based microparticles loaded with human immunoglobulin (hIgG) or control peptide were synthesized by spray drying and tested for: i) the kinetics of peptide/protein release, using ELISA and bioassays; ii) bioavailability subsequent to nonaqueous liquid instillation into the respiratory tract of BALB/c mice, using ELISA and Western blotting; iii) bioactivity in terms of murine immune response to xenotypic epitopes on human IgG, using ELISA and T cell assays; and iv) mechanisms responsible for the observed enhancement of immune responses, using measurement of antibodies as well as tagged probes.

RESULTS

Human IgG and the control peptide were both readily released from the hollow-porous microspheres once added to an aqueous environment, although the kinetics depended on the compound. Nonaqueous liquid instillation of hIgG formulated in PulmoSpheres into the upper and lower respiratory tract of BALB/c mice resulted in systemic biodistribution. The formulated human IgG triggered enhanced local and systemic immune responses against xenotypic epitopes and was associated with receptor-mediated loading of alveolar macrophages.

CONCLUSIONS

Formulation of immunoglobulins in hollow-porous microparticles is compatible with local and systemic delivery via the respiratory mucosa and may be used as means to trigger or modulate immune responses.

Platelet protein kinase C alpha levels in drug-free and lithium-treated subjects with bipolar disorder

Recent studies suggest that protein kinase C (PKC), particularly the alpha isoform, plays an important role in the action of lithium. There is, however, little evidence from patients with bipolar disorder (BD) to support this effect. The present investigation carried out comparative studies of PKC levels in platelets obtained from BD subjects including those with and without lithium treatment. All subjects met DSM-IV criteria for BD type I confirmed by structured interview (SCID-IV). Levels of PKC-alpha isoform in platelets from controls and from BD subjects were measured with immunoblotting analysis. No significant differences were found between controls, drug-free or lithium-treated BD subjects on membrane or cytosolic levels of PKC-alpha or in the membrane-to-cytosol ratio of this protein. The present study suggests that levels of PKC-alpha do not change in the peripheral tissues of BD subjects with or without lithium treatment.