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Dive into the research topics where Gregor J. Brown is active.

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Featured researches published by Gregor J. Brown.


Gastroenterology | 2011

Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.

Alan Moss; Michael J. Bourke; Stephen J. Williams; Luke F. Hourigan; Gregor J. Brown; William Tam; Rajvinder Singh; Simon A. Zanati; Robert Chen; Karen Byth

BACKGROUND & AIMS Large sessile colonic polyps usually are managed surgically, with significant morbidity and potential mortality. There have been few prospective, intention-to-treat, multicenter studies of endoscopic mucosal resection (EMR). We investigated whether endoscopic criteria can predict invasive disease and direct the optimal treatment strategy. METHODS The Australian Colonic Endoscopic (ACE) resection study group conducted a prospective, multicenter, observational study of all patients referred for EMR of sessile colorectal polyps that were 20 mm or greater in size (n=479, mean age, 68.5 y; mean lesion size, 35.6 mm). We analyzed data on lesion characteristics and procedural, clinical, and histologic outcomes. Multiple logistic regression analysis identified independent predictors of EMR efficacy and recurrence of adenoma, based on findings from follow-up colonoscopy examinations. RESULTS Risk factors for submucosal invasion were as follows: Paris classification 0-IIa+c morphology, nongranular surface, and Kudo pit pattern type V. The most commonly observed lesion (0-IIa granular) had a low rate of submucosal invasion (1.4%). EMR was effective at completely removing the polyp in a single session in 89.2% of patients; risk factors for lack of efficacy included a prior attempt at EMR (odds ratio [OR], 3.8; 95% confidence interval, 1.77-7.94; P=.001) and ileocecal valve involvement (OR, 3.4; 95% confidence interval, 1.20-9.52; P=.021). Independent predictors of recurrence after effective EMR were lesion size greater than 40 mm (OR, 4.37; 95% confidence interval, 2.43-7.88; P<.001) and use of argon plasma coagulation (OR, 3.51; 95% confidence interval, 1.69-7.27; P=.0017). There were no deaths from EMR; 83.7% of patients avoided surgery. CONCLUSIONS Large sessile colonic polyps can be managed safely and effectively by endoscopy. Endoscopic assessment identifies lesions at increased risk of containing submucosal cancer. The first EMR is an important determinant of patient outcome-a previous attempt is a significant risk factor for lack of efficacy.


PLOS Pathogens | 2014

Activation of HIV Transcription with Short-Course Vorinostat in HIV-Infected Patients on Suppressive Antiretroviral Therapy

Julian Elliott; Fiona Wightman; Ajantha Solomon; Khader Ghneim; Jeffrey D. Ahlers; Mark J. Cameron; Miranda Z. Smith; Tim Spelman; James H. McMahon; Pushparaj Velayudham; Gregor J. Brown; Janine Roney; Jo Watson; Miles Prince; Jennifer Hoy; Nicolas Chomont; Rémi Fromentin; Francesco A. Procopio; Joumana Zeidan; Sarah Palmer; Lina Odevall; Ricky W. Johnstone; Ben P. Martin; Elizabeth Sinclair; Steven G. Deeks; Daria J. Hazuda; Paul U. Cameron; Rafick-Pierre Sekaly; Sharon R. Lewin

Human immunodeficiency virus (HIV) persistence in latently infected resting memory CD4+ T-cells is the major barrier to HIV cure. Cellular histone deacetylases (HDACs) are important in maintaining HIV latency and histone deacetylase inhibitors (HDACi) may reverse latency by activating HIV transcription from latently infected CD4+ T-cells. We performed a single arm, open label, proof-of-concept study in which vorinostat, a pan-HDACi, was administered 400 mg orally once daily for 14 days to 20 HIV-infected individuals on suppressive antiretroviral therapy (ART). The primary endpoint was change in cell associated unspliced (CA-US) HIV RNA in total CD4+ T-cells from blood at day 14. The study is registered at ClinicalTrials.gov (NCT01365065). Vorinostat was safe and well tolerated and there were no dose modifications or study drug discontinuations. CA-US HIV RNA in blood increased significantly in 18/20 patients (90%) with a median fold change from baseline to peak value of 7.4 (IQR 3.4, 9.1). CA-US RNA was significantly elevated 8 hours post drug and remained elevated 70 days after last dose. Significant early changes in expression of genes associated with chromatin remodeling and activation of HIV transcription correlated with the magnitude of increased CA-US HIV RNA. There were no statistically significant changes in plasma HIV RNA, concentration of HIV DNA, integrated DNA, inducible virus in CD4+ T-cells or markers of T-cell activation. Vorinostat induced a significant and sustained increase in HIV transcription from latency in the majority of HIV-infected patients. However, additional interventions will be needed to efficiently induce virus production and ultimately eliminate latently infected cells. Trial Registration ClinicalTrials.gov NCT01365065


Gut | 2015

Long-term adenoma recurrence following wide-field endoscopic mucosal resection (WF-EMR) for advanced colonic mucosal neoplasia is infrequent: results and risk factors in 1000 cases from the Australian Colonic EMR (ACE) study

Alan Moss; Stephen J. Williams; Luke F. Hourigan; Gregor J. Brown; William Tam; Rajvinder Singh; Simon A. Zanati; Nicholas G. Burgess; Rebecca Sonson; Karen Byth; Michael J. Bourke

Objective Wide-field endoscopic mucosal resection (WF-EMR) is an alternative to surgery for treatment of advanced colonic mucosal neoplasia up to 120 mm in size, but has been criticised for its potentially high recurrence rates. We aimed to quantify recurrence at 4 months (early) and 16 months (late) following successful WF-EMR and identify its risk factors and clinical significance. Design Ongoing multicentre, prospective, intention-to-treat analysis of sessile or laterally spreading colonic lesions ≥20 mm in size referred for WF-EMR to seven academic endoscopy units. Surveillance colonoscopy (SC) was performed 4 months (SC1) and 16 months (SC2) after WF-EMR, with photographic documentation and biopsy of the scar. Results 1134 consecutive patients were enrolled when 1000 successful EMRs were achieved, of whom 799 have undergone SC1. 670 were normal. Early recurrent/residual adenoma was present in 128 (16.0%, 95% CI 13.6% to 18.7%). One case was unknown. The recurrent/residual adenoma was diminutive in 71.7% of cases. On multivariable analysis, risk factors were lesion size >40 mm, use of argon plasma coagulation and intraprocedural bleeding. Of 670 with normal SC1, 426 have undergone SC2, with late recurrence present in 17 cases (4.0%, 95% CI 2.4% to 6.2%). Overall, recurrent/residual adenoma was successfully treated endoscopically in 135 of 145 cases (93.1%, 95% CI 88.1% to 96.4%). If the initial EMR was deemed successful and did not contain submucosal invasion requiring surgery, 98.1% (95% CI 96.6% to 99.0%) were adenoma-free and had avoided surgery at 16 months following EMR. Conclusions Following colonic WF-EMR, early recurrent/residual adenoma occurs in 16%, and is usually unifocal and diminutive. Risk factors were identified. Late recurrence occurs in 4%. Overall, recurrence was managed endoscopically in 93% of cases. Recurrence is not a significant clinical problem following WF-EMR, as with strict colonoscopic surveillance, it can be managed endoscopically with high success rates. Trial registration number: NCT01368289.


Clinical Immunology | 2010

The effects of ALV003 pre-digestion of gluten on immune response and symptoms in celiac disease in vivo

Jason A. Tye-Din; Robert P. Anderson; Rosemary A. Ffrench; Gregor J. Brown; Peter Hodsman; Matthew Siegel; Wendy Botwick; Revati Shreeniwas

Effective treatment of celiac disease is an unmet medical need. A glutenase that destroys immunogenic gluten peptides may be clinically valuable. Twenty patients with celiac disease were randomly assigned to ingest a large gluten meal (16 g daily for 3 days) pre-treated with ALV003, a mixture of highly specific glutenases (n=10), or pre-treated with placebo (n=10). Peripheral blood T-cell IFN-gamma ELISpot responses to gliadin and an immunogenic 33mer and symptoms were assessed. While baseline IFN-gamma ELISpot responses to gliadin and the 33mer were negative in all patients, a significant ELISpot response to gliadin or the 33mer was observed in 6 of 10 patients consuming placebo-treated gluten and 0 of 10 consuming ALV003 pre-treated gluten (p=0.011). Symptoms typically associated with gluten ingestion occurred in both groups and were not significantly reduced by ALV003 pre-treatment. ALV003 pre-treatment can abolish immune responses induced by gluten in patients with celiac disease.


Clinical Gastroenterology and Hepatology | 2014

Risk Factors for Intraprocedural and Clinically Significant Delayed Bleeding After Wide-field Endoscopic Mucosal Resection of Large Colonic Lesions

Nicholas G. Burgess; Andrew J. Metz; Stephen J. Williams; Rajvinder Singh; William Tam; Luke F. Hourigan; Simon A. Zanati; Gregor J. Brown; Rebecca Sonson; Michael J. Bourke

BACKGROUND & AIMS Wide-field endoscopic mucosal resection (WF-EMR) of large sessile colonic polyps is a safe and cost-effective outpatient treatment. Bleeding is the main complication. Few studies have examined risk factors for bleeding during the procedure (intraprocedural bleeding [IPB]) or after it (clinically significant post-endoscopic bleeding [CSPEB]). We investigated factors associated with IPB and CSPEB in a large prospective study. METHODS We analyzed data from WF-EMRs of sessile colorectal polyps ≥ 20 mm in size (mean size, 35.5 mm), which were performed on 1172 patients (mean age, 67.8 years) from June 2008-March 2013 at 7 tertiary hospitals as part of the Australian Colonic Endoscopic Resection Study. Data were collected on characteristics of patients and lesions, along with outcomes of procedures and clinical and histologic analyses. Independent predictors of IPB and CSPEB were identified by multiple logistic regression analysis. RESULTS Of the patients studied, 133 (11.3%) had IPB. Independent predictors included increasing lesion size (odds ratio, 1.24/10 mm; P < .001), Paris endoscopic classification of 0-IIa + Is (odds ratio, 2.12; P = .004), tubulovillous or villous histology (odds ratio, 1.84; P = .007), and study institutions that performed the procedure on fewer than 75 patients (odds ratio, 3.78; P < .001). All IPB was successfully controlled endoscopically. IPB prolonged procedures and was associated with early recurrence (relative risk, 1.68; P = .011). Seventy-three patients (6.2%) had CSPEB. On multivariable analysis, CSPEB was associated with proximal colon location (odds ratio, 3.72; P < .001), use of an electrosurgical current not controlled by a microprocessor (odds ratio, 2.03; P = .038), and IPB (odds ratio, 2.16; P = .016). Lesion size and comorbidities did not predict CSPEB. CONCLUSIONS In a prospective study of patients undergoing WF-EMR of large sessile colonic polyps, IPB is associated with larger lesions, lesion histology, and Paris endoscopic classification of type 0-IIa + Is. IPB prolongs the duration of the procedure, is a marker for recurrence, and is associated with CSPEB. CSPEB occurs most frequently in the proximal colon and less when current is controlled by a microprocessor.


Clinical Gastroenterology and Hepatology | 2016

Cost Analysis of Endoscopic Mucosal Resection vs Surgery for Large Laterally Spreading Colorectal Lesions

Mahesh Jayanna; Nicholas G. Burgess; Rajvinder Singh; Luke F. Hourigan; Gregor J. Brown; Simon A. Zanati; Alan Moss; James Lim; Rebecca Sonson; Stephen J. Williams; Michael J. Bourke

BACKGROUND & AIMS Large laterally spreading lesions (LSL) in the colon and rectum can be safely and effectively removed by endoscopic mucosal resection (EMR). However, many patients still undergo surgery. Endoscopic treatment may be more cost effective. We compared the costs of endoscopic versus surgical management of large LSL. METHODS We performed a prospective, observational, multicenter study of consecutive patients referred to 1 of 7 academic hospitals in Australia for the management of large LSL (≥ 20 mm) from January 2010 to December 2013. We collected data on numbers of patients undergoing EMR, actual endoscopic management costs (index colonoscopy, hospital stay, adverse events, and first surveillance colonoscopy), characteristics of patients and lesions, outcomes, and adverse events, and findings from follow-up examinations 14 days, 4-6 months, and 16-18 months after treatment. We compared data from patients who underwent EMR with those from a model in which all patients underwent surgery without any complications. Event-specific costs, based on Australian refined diagnosis-related group codes, were used to estimate average cost per patient. RESULTS EMR was performed on 1489 lesions (mean size, 36 mm) in 1353 patients (mean age, 67 years; 52.1% male). Total costs involved in the endoscopic management of large LSL were US


Gut | 2017

Endoscopic mucosal resection for large serrated lesions in comparison with adenomas: a prospective multicentre study of 2000 lesions

Maria Pellise; Nicholas G. Burgess; Nicholas Tutticci; Luke F. Hourigan; Simon A. Zanati; Gregor J. Brown; Rajvinder Singh; Stephen J. Williams; Spiro C. Raftopoulos; Donald Ormonde; Alan Moss; Karen Byth; Heok P'Ng; Hema Mahajan; Duncan McLeod; Michael J. Bourke

6,316,593 and total inpatient hospitalization length of stay was 1180 days. The total cost predicted for the surgical management group was US


Gastrointestinal Endoscopy | 2012

SINGLE-01: a randomized, controlled trial comparing the efficacy and depth of insertion of single- and double-balloon enteroscopy by using a novel method to determine insertion depth.

Marios Efthymiou; Paul V. Desmond; Gregor J. Brown; Richard La Nauze; Arthur J. Kaffes; Tee Joo Chua; Andrew C. Taylor

16,601,502, with a total inpatient hospitalization length of stay of 4986 days. Endoscopic management produced a potential total cost saving of US


Clinical Cancer Research | 2006

Germ Line Mutations of Mismatch Repair Genes in Hereditary Nonpolyposis Colorectal Cancer Patients with Small Bowel Cancer: International Society for Gastrointestinal Hereditary Tumours Collaborative Study

Jae-Gahb Park; Duck-Woo Kim; Chang Won Hong; Byung-Ho Nam; Young-Kyoung Shin; Sung-Hye Hong; Il-Jin Kim; Seok-Byung Lim; Melyssa Aronson; Marie Luise Bisgaard; Gregor J. Brown; John Burn; Elizabeth Chow; Peggy Conrad; Fiona Douglas; Malcolm G. Dunlop; James M. Ford; Marc S. Greenblatt; Jarvinen Heikki; Karl Heinimann; Elly Lynch; Finlay Macrae; Wendy McKinnon; Gabriela Moeslein; Benedito Mauro Rossi; Paul Rozen; Lyn Schofield; Carlos Vaccaro; Hans F. A. Vasen; M.E. Velthuizen

10,284,909; the mean cost difference per patient was US


Gut | 2016

Clinical and endoscopic predictors of cytological dysplasia or cancer in a prospective multicentre study of large sessile serrated adenomas/polyps

Nicholas G. Burgess; Maria Pellise; Kavinderjit S. Nanda; Luke F. Hourigan; Simon A. Zanati; Gregor J. Brown; Rajvinder Singh; Stephen J. Williams; Spiro C. Raftopoulos; Donald Ormonde; Alan Moss; Karen Byth; Heok P'Ng; Duncan McLeod; Michael J. Bourke

7602 (95% confidence interval,

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Luke F. Hourigan

Princess Alexandra Hospital

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Alan C. Moss

Beth Israel Deaconess Medical Center

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Spiro C. Raftopoulos

Sir Charles Gairdner Hospital

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