John Field

The Queen Elizabeth Hospital, Tarndarnya, South Australia, Australia

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Publications (10)17.07 Total impact

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    ABSTRACT: Quantitative assays of mucosal biofilms on ex vivo samples are challenging using the currently applied specialized microscopic techniques to identify them. The COMSTAT2 computer program has been applied to in vitro biofilm models for quantifying biofilm structures seen on confocal scanning laser microscopy (CSLM). The aim of this study was to quantify Staphylococcus aureus (S. aureus) biofilms seen via CSLM on ex situ samples of sinonasal mucosa, using the COMSTAT2 program. S. aureus biofilms were grown in frontal sinuses of 4 merino sheep as per a previously standardized sheep sinusitis model for biofilms. Two sinonasal mucosal samples, 10 mm × 10 mm in size, from each of the 2 sinuses of the 4 sheep were analyzed for biofilm presence with Baclight stain and CSLM. Two random image stacks of mucosa with S. aureus biofilm were recorded from each sample, and analyzed using COMSTAT2 software that translates image stacks into a simplified 3-dimensional matrix of biofilm mass by eliminating surrounding host tissue. Three independent observers analyzed images using COMSTAT2 and 3 repeated rounds of analyses were done to calculate biofilm biomass. The COMSTAT2 application uses an observer-dependent threshold setting to translate CSLM biofilm images into a simplified 3-dimensional output for quantitative analysis. Intraclass correlation coefficient (ICC) between thresholds set by the 3 observers for each image stacks was 0.59 (p = 0.0003). Threshold values set at different points of time by a single observer also showed significant correlation as seen by ICC of 0.80 (p < 0.001). COMSTAT2 can be applied to quantify and study the complex 3-dimensional biofilm structures that are recorded via CSLM on mucosal tissue like the sinonasal mucosa.
    International Forum of Allergy and Rhinology 01/2012; 2(1):57-62. · 1.00 Impact Factor
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    ABSTRACT: The relationship between sinonasal nitric oxide (NO) levels and the pathogenic organism Staphylococcus aureus is yet to be established. High NO levels measured in healthy sinuses likely contribute to maintenance of relative sterility. Lower concentrations such as is found in the sinuses of chronic rhinosinusitis (CRS) patients may decrease this effect. S. aureus in biofilm form has recently been implicated in recalcitrant CRS, its isolation predicting a higher risk of posttreatment reinfection. This in vitro study aims to characterize the changes in S. aureus biofilm formation when exposed to different NO levels mimicking the normal and diseased NO sinus concentrations reported in previous literature in an in vitro setting. S. aureus ATCC 25923 and 7 clinical isolates were cultured in biofilm form using the MBEC device and the established biofilms exposed to 1 to 1000 μM NO concentrations. Biofilms were visualized using Live/Dead Baclight stain and confocal scanning laser microscopy, and quantified using Comstat2, a biofilm quantification software. Biofilm biomass decreases from an average of 0.105 to 0.057 μm(3) /μm(2) at higher NO concentrations (125-1000 μM), but is increased to 0.470 μm(3) /μm(2) at lower NO concentrations (0.9-2.0 μM). The average biomass at high vs low concentrations are statistically significant (p < 0.001). S. aureus biofilm formation varies across exposure to different NO levels, with antibiofilm effects at higher concentrations, and enhanced biofilm formation at lower or subphysiologic concentrations. These results coincide with the often dualistic function of NO, and have implications in its future use in the treatment of CRS.
    International Forum of Allergy and Rhinology 11/2011; 1(6):438-44. · 1.00 Impact Factor
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    ABSTRACT: The etiopathogenesis of chronic rhinosinusitis (CRS) is currently an area of intense debate. Recently, biofilms have been proposed as a potential environmental trigger in this disease. In particular, Staphylococcus aureus biofilms appear to be a predictor of severe disease recalcitrant to current treatment paradigms. However, direct causal links between biofilms and host immune activation are currently lacking. This study aimed to document both the adaptive immune responses that characterize S. aureus biofilm-associated CRS and the relative contributions of staphylococcal superantigens and S. aureus biofilms in the inflammatory make-up of this disease. A total of 53 disease subjects and 15 controls were recruited. Sinonasal mucosa was collected for the determination of S. aureus and Haemophilus influenzae biofilms and presence of total and superantigen-specific IgE and for the measurement of cytokines that characterize the T-helper pathways. Staphylococcus aureus biofilms and superantigens are significantly associated in CRS patients, suggesting the biofilm may be a nidus for superantigen-eluting bacteria. The presence of S. aureus biofilms is associated with eosinophilic inflammation, across the spectrum of CRS, on the back of a T-helper(2) skewing of the host's adaptive immune response (elevated Eosinophilic Cationic Protein and IL-5). This can be distinguished from the superantigenic effect resulting in the induction of IgE. This study provides novel evidence of a link between S. aureus biofilms and skewing of the T-cell response toward the T-helper(2) pathway that is independent of superantigen activities. Further research is required to confirm the cause-effect relationship of this association.
    Allergy 08/2011; 66(11):1449-56. · 5.88 Impact Factor
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    ABSTRACT: We investigated the effect of simulated bleeding on plasminogen activity, matrix metalloproteinase (MMP) expression, and wound healing using a human fibroblast model. Nasal fibroblasts from three chronic rhinosinusitis (CRS) patients with nasal polyps and three controls were grown in culture and a standardized injury was created using a punch. To mimic bleeding, fibroblasts were stimulated with plasminogen (100 microg/mL), plasminogen + tranexamic acid (TA; 100 microg/mL) or media only. At 24, 48, and 72 hours after injury, we measured urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activities and inactive and active MMP-2 and -9 expression. Injury stimulated the nasal fibroblasts to express uPA and tPA and active and inactive MMP-2 and -9. In CRS patients, plasminogen significantly decreased MMP-9 expression after 48 hours (p < 0.04). In untreated fibroblasts, we observed a decrease in active MMP-9 expression, whereas plasminogen increased active MMP-9 expression after 48 hours (p < 0.04). At 24 hours, active MMP-9 expression was reduced by plasminogen +/- TA (p < 0.02). Plasminogen also stimulated uPA expression in CRS patient fibroblasts after 48 hours (p < 0.04). Fibroblast proliferation occurred when exposed to plasminogen and was strongly modulated by uPA and inactive and active MMP-2. The quality of wound healing was affected by inactive MMP-2, uPA and tPA, simulation, and inhibition of bleeding. Activation of the plasminogen pathway and inactive MMP-2 expression tended to increase both proliferation of nasal fibroblasts and MMP-9 expression as a marker for deterioration of the quality of wound healing.
    American Journal of Rhinology and Allergy 01/2010; 24(3):186-91.
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    ABSTRACT: Differentiating normal nasal discharge and postoperative crust from infection after endoscopic sinus surgery (ESS) can be difficult. We investigated whether bacteria cultured at operation was predictive for postoperative mucosal infection-defined as frank pus, thick mucus, and/or abnormal crusting seen on endoscopic examination associated with positive microbiology. The records of 48 patients with chronic rhinosinusitis (CRS) with infection at the time of ESS were retrospectively reviewed. Results of intraoperative cultures were compared with those taken at the time of postoperative mucosal infection. Fourteen of 16 patients (87.5%) with intraoperative infection with Staphylococcus aureus progressed to postoperative mucosal infection with S. aureus, whereas patients who cultured "other" bacteria intraoperatively progressed to postoperative mucosal infection in 6/19 cases (31.6%), with S. aureus cultured in only 3/19 cases (15.8%; p=0.0001). S. aureus infection at ESS predicts for abnormal, S. aureus-associated mucosal healing and infection post-ESS. Although a prospective trial is warranted, these findings suggest a future role for aggressive anti-S. aureus therapy peri- and/or postoperatively in patients who culture positive for this organism to improve postsurgical outcomes.
    American journal of rhinology & allergy 01/2009; 23(5):549-52. · 1.74 Impact Factor
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    ABSTRACT: Endoscopic sinus surgery is an accepted treatment for medically recalcitrant chronic rhinosinusitis. Effective saline douching may improve long-term outcomes of chronic rhinosinusitis but is often impaired by postoperative ostial stenosis. The aim of this study is to determine a critical ostial size at which douching solution reliably enters the sinus cavities. Prospective study of consecutive patient cohort. Seventeen preoperative or well-healed postoperative endoscopic sinus surgery patients were irrigated with 5 mL blue food coloring mixed with 200 mL buffered saline from a squeeze bottle. The degree of sinus penetration, sinus ostial patency, and ostial size were endoscopically determined. Sinuses penetrated by blue dye had a significantly larger minimal ostial dimension (7.31 mm; 95% confidence interval 5.54-9.08) than those that had no blue dye penetration (1.26 mm; 95% confidence interval 0.86-1.66) as determined by Student t test. Chi-square analysis showed that operated sinuses were more likely to be penetrated than nonoperated sinuses (P = .0016) and obstructed sinuses (P = .0325). Logistic regression showed a 95% probability of penetration when the minimum ostial dimension is 3.95 mm or greater. Unoperated sinuses or cases with gross sinus ostial obstruction will not be reliably penetrated by sinus irrigant. A 3.95-mm ostial diameter seems to be the minimum size to guarantee penetration in paranasal sinuses to maximize the potential for topical sinus treatment.
    The Laryngoscope 11/2008; 118(11):2078-81. · 1.98 Impact Factor
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    ABSTRACT: Bleeding is a major concern in endoscopic sinus surgery (ESS), as it may impede surgical progress and is often associated with complications. To improve the study and management of intraoperative bleeding, a standardized method of recording bleeding during ESS is needed. The aim of this study was to develop a standardized method of documenting bleeding in ESS and of grading the surgical field. Bleeding after endoscopic sinus surgery was recorded using video-endoscopy. Standardized and non-standardized video-endoscopies of 20 patients were graded using a previously published grading scale (the Boezaart scale) in randomized order on two different occasions. Effects of standardization on intra- and interrater reliability were evaluated.Based on this experience, a new 11-point surgical field grading scale was developed and simultaneously compared with the six-point Boezaart scale via means of a DVD in three international centers. Inter and intrarater reliability of the Boezaart and new Wormald scales significantly improved by employing a standardized video-endoscopy technique. The Wormald scale had significantly higher interrater (0.80 vs. 0.74, P < .001) and intrarater (0.89 vs. 0.83, P < .001) reliability than the Boezaart scale. Linear regression analysis revealed the Wormald scale to be more sensitive to changes in the most common surgical fields experienced in ESS. Standardized video-endoscopy has been demonstrated to significantly improve reliability and reproducibility of results and is recommended for future work evaluating bleeding in ESS. The new Wormald grading scale has been shown to be an inexpensive, reliable, and sensitive tool to rapidly evaluate intraoperative bleeding in ESS. It overcomes several limitations of the Boezaart scale, enabling us to analyze currently employed and newly developed hemostatic methods and agents.
    The Laryngoscope 02/2008; 118(2):314-9. · 1.98 Impact Factor
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    ABSTRACT: Bleeding is a major concern in endoscopic sinus surgery (ESS) as it may impede surgical progress and is often associated with complications. To improve the study and management of intraoperative bleeding, a standardized method of recording bleeding during ESS is needed. The aim of this study was to develop a standardized method of documenting bleeding in ESS and of grading the surgical field.
    Peter-John Wormald.
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    ABSTRACT: Postoperative irrigation after endoscopic sinus surgery and endoscopic modified Lothrop procedure is used to remove nasal crusts and to improve wound healing. To evaluate the optimal application protocol for irrigation of the frontal sinus, a prospective cadaver study was performed. An endoscopic modified Lothrop procedure and complete sphenoethmoidectomy were performed in 19 heads. Each was irrigated with a 1.5% solution of water and different colors using nasal spray and a squeeze bottle filled with 50, 100, and 200 mL. Intensity of local staining and percentage of area were documented using standardized videoendoscopy after irrigation in "bending over the sink" or "vertex to floor" position. Grading was performed by two independent observers for 23 anatomic regions, including the stained circumference of maxillary and frontal ostia. To evaluate the influence of the anatomy, acoustic rhinometry was performed. ANOVA was used to evaluate effects of application methods and head positions using GenStat 8.2 (Lawes Agricultural Trust, Rothamsted Experimental Station, Harpenden, U.K.) using an appropriate block structure. With regard to the frontal sinus, we were able to show clear superiority of the squeeze bottle technique filled with 200 mL and applied in the "vertex to floor position." Conclusion: In a relatively fit and flexible patient the vertex to floor position using a squeeze bottle technique is advocated. There may be some patients, however, for whom this position is not feasible. In these patients "bending over the sink," while inferior to the "vertex to floor" position, still ensures some irrigation of the frontal sinus.
    American journal of rhinology & allergy 23(1):85-90. · 1.74 Impact Factor
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    ABSTRACT: The Lund-MacKay score (LMS) is the standard for communicating radiological extent of chronic rhinosinusitis in research. However, retrospective analyses are often hindered by a substantial lack of radiological data. Calculating LMS from radiologists' reports may overcome this but has not been formally validated. Twenty South Australian and 20 Texan patients with varying degrees of sinus disease were randomly chosen to undergo analysis. CT-derived LMSs were calculated directly by two expert rhinologists at each institution and compared with scores derived solely from accompanying radiology reports by two blinded reviewers. The total LMS obtained via the expert rhinologists correlated very highly with that obtained from radiology reports (Spearman rank correlation, 0.75-0.88; p < 0.001). However, when individual sinuses were specifically analyzed, the correlation was highly variable. The results show that in both South Australian and Texan tertiary rhinology centers, radiologists' reports can be reliably used to calculate the total LMS.
    American journal of rhinology & allergy 23(1):33-5. · 1.74 Impact Factor

Publication Stats

147 Citations
17.07 Total Impact Points

Institutions

  • 2008–2012
    • The Queen Elizabeth Hospital
      • Department of Surgery
      Tarndarnya, South Australia, Australia
  • 2011
    • Universitair Ziekenhuis Ghent
      Gand, Flanders, Belgium
  • 2008–2009
    • University of Adelaide
      • • Discipline of Otolaryngology, Head and Neck Surgery
      • • Faculty of Health Sciences
      Adelaide, South Australia, Australia