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Featured researches published by Zahir Amin.


The American Journal of Gastroenterology | 2007

Autoimmune Pancreatitis: Clinical and Radiological Features and Objective Response to Steroid Therapy in a UK Series

Nicholas I. Church; Stephen P. Pereira; Maesha Deheragoda; Neomal S. Sandanayake; Zahir Amin; William R. Lees; Alice Gillams; Manuel Rodriguez-Justo; Marco Novelli; E Seward; Adrian R. Hatfield; George Webster

OBJECTIVE:Most cases of autoimmune pancreatitis (AIP) have been reported from Japan. We present data on a UK series, including clinical and radiological features at presentation, and longitudinal response to immunosuppression.METHODS:Over an 18-month period, all patients diagnosed in our center with AIP were studied. Endoscopic biliary stenting was performed as required, and patients were treated with prednisolone, with response assessed longitudinally. In cases of disease relapse following steroid reduction, azathioprine was instituted.RESULTS:Eleven patients met diagnostic criteria for AIP. Diffuse pancreatic enlargement was seen in eight patients (73%), and pancreatic duct strictures in all. Seven patients required biliary stents. Extrapancreatic involvement occurred in all, including intrahepatic stricturing and renal disease. Eight weeks after starting steroids, the median serum bilirubin level had fallen from 38 μmol/L to 11 μmol/L (P = 0.001), and ALT from 97 IU/L to 39 IU/L (P = 0.002). Stents were removed in all cases, with no recurrence of jaundice. Improvements in mass lesions and pancreaticobiliary stricturing occurred in all patients. During a median 18-month follow-up, six patients relapsed, four of whom responded to azathioprine. Two patients discontinued steroids and remained well.CONCLUSIONS:Extrapancreatic disease was an important feature of AIP in this UK series. Initial response to immunosuppressive therapy was excellent, but disease relapse was common. Optimal long-term management remains to be established.


Clinical Gastroenterology and Hepatology | 2009

Presentation and Management of Post-treatment Relapse in Autoimmune Pancreatitis/Immunoglobulin G4-Associated Cholangitis

Neomal S. Sandanayake; Nicholas I. Church; Michael H. Chapman; Gavin J. Johnson; Dipok Kumar Dhar; Zahir Amin; Maesha Deheragoda; Marco Novelli; Alison Winstanley; Manuel Rodriguez–Justo; Adrian R. Hatfield; Stephen P. Pereira; George Webster

BACKGROUND & AIMS Autoimmune pancreatitis (AIP) is a multisystem disorder that often has extrapancreatic manifestations such as immunoglobulin G4-associated cholangitis (IAC). Patients respond rapidly to steroids but can relapse after therapy. We assessed the clinical management of relapse in a group of patients with AIP/IAC. METHODS We performed a prospective study of patients diagnosed with AIP from 2004-2007 who received steroids. Treatment outcome was defined clinically, radiologically, and biochemically as response to steroids, remission after steroids, failure to wean steroids, and relapse. Steroids +/- azathioprine (AZA) were used to treat patients who failed, relapsed, or could not be weaned from steroids. RESULTS Twenty-eight patients with AIP were studied; 23 (82%) had IAC. All patients responded within 6 weeks to prednisolone therapy. Twenty-three patients achieved remission after a median of 5 months of treatment (range, 1.5-17 months), whereas 5 patients (18%) could not be weaned because of a disease flare. Of the patients who achieved remission, 8 of 23 (35%) subsequently relapsed. Overall, 13 of 23 patients (57%) with AIP/IAC relapsed, compared with 0 of the 5 with isolated AIP (P = .04, Fisher exact test). Steroids were increased/restarted in all patients who relapsed; 10 also received AZA. Remission was achieved and maintained in 7 patients; they remain on AZA monotherapy at a median of 14 months (range, 1-27 months). CONCLUSIONS Relapse or failure to wean steroids occurred in 46% of patients with AIP. Patients with IAC are at particularly high risk of relapse. AZA appears to be effective in patients with post-treatment relapse or who cannot be weaned from steroids. To view this articles video abstract, go to the AGAs YouTube Channel.


Clinical Radiology | 1993

Local treatment of colorectal liver metastases: A comparison of Interstitial Laser Photocoagulation (ILP) and Percutaneous Alcohol Injection (PAI)

Zahir Amin; Stephen G. Bown; W.R. Lees

The purpose of this study was to evaluate the relative merits of two physical methods of locally destroying colorectal liver metastases-interstitial laser photocoagulation (ILP) which causes thermal necrosis, and percutaneous alcohol injection (PAI) which causes cellular dehydration and coagulative necrosis. Seventy-six liver metastases in 22 patients were treated by ILP or PAI. Both techniques were performed using local anaesthesia and intravenous sedation/analgesia. Ultrasound was used to localize the tumours and guide the needles percutaneously. ILP: Up to eight 19 G needles were inserted into the tumour, and down each needle was passed a thin optical fibre; the tumour was heated using low power laser light (2 W) for 500 s from a Nd:YAG or diode laser. PAI: 0.5-1 ml of sterile 95% absolute alcohol was injected into multiple sites of the tumour using a single 19-22 G needle. Dynamic CT scan was used to evaluate the extent of treatment-induced necrosis. Ultrasound showed echogenic changes around the needles/fibre-tips during ILP and PAI; this gave a reasonable guide to the extent of thermal damage for smaller tumours during ILP, but not during PAI. ILP: 54 tumours were treated (median size 2.7 cm). Laser-induced necrosis was clearly seen 24 h after treatment as a well-defined area of non-enhancement on the dynamic CT scan; greater than 50% necrosis of tumour volume was achieved in 87% of tumours (complete necrosis was found in 52% of tumours). PAI: 22 tumours were treated (median size 1.5 cm). Dynamic CT showed patchy areas of non-enhancement in five tumours, decreased density in seven tumours, and no change in 10 tumours; complete tumour necrosis was never achieved. There were no major complications after ILP or PAI, but pain during treatment was more common and more severe with PAI. ILP is a simple, safe and effective treatment for colorectal liver metastases; PAI is relatively ineffective for these tumours (although it has been shown to be much more effective for small hepatocellular carcinomas).


Gut | 2011

Endoscopic retrograde pancreatography criteria to diagnose autoimmune pancreatitis: an international multicentre study

Aravind Sugumar; Michael J. Levy; Terumi Kamisawa; George Webster; Myung-Hwan Kim; Felicity Enders; Zahir Amin; Todd H. Baron; Mh Chapman; Nicholas I. Church; Jonathan E. Clain; Naoto Egawa; Gavin J. Johnson; Kazuichi Okazaki; Randall K. Pearson; Stephen P. Pereira; Bret T. Petersen; Samantha Read; Raghuwansh P. Sah; Neomal S. Sandanayake; Naoki Takahashi; Mark Topazian; Kazushige Uchida; Santhi Swaroop Vege; Suresh T. Chari

Background Characteristic pancreatic duct changes on endoscopic retrograde pancreatography (ERP) have been described in autoimmune pancreatitis (AIP). The performance characteristics of ERP to diagnose AIP were determined. Methods The study was done in two phases. In phase I, 21 physicians from four centres in Asia, Europe and the USA, unaware of the clinical data or diagnoses, reviewed 40 preselected ERPs of patients with AIP (n=20), chronic pancreatitis (n=10) and pancreatic cancer (n=10). Physicians noted the presence or absence of key pancreatographic features and ranked the diagnostic possibilities. For phase II, a teaching module was created based on features found most useful in the diagnosis of AIP by the four best performing physicians in phase I. After a washout period of 3 months, all physicians reviewed the teaching module and reanalysed the same set of ERPs, unaware of their performance in phase I. Results In phase I the sensitivity, specificity and interobserver agreement of ERP alone to diagnose AIP were 44, 92 and 0.23, respectively. The four key features of AIP identified in phase I were (i) long (>1/3 the length of the pancreatic duct) stricture; (ii) lack of upstream dilatation from the stricture (<5 mm); (iii) multiple strictures; and (iv) side branches arising from a strictured segment. In phase II the sensitivity (71%) of ERP significantly improved (p<0.05) without a significant decline in specificity (83%) (p>0.05); the interobserver agreement was fair (0.40). Conclusions The ability to diagnose AIP based on ERP features alone is limited but can be improved with knowledge of some key features.


Clinical Gastroenterology and Hepatology | 2011

Endoscopic Retrograde Cholangiography Does Not Reliably Distinguish IgG4-Associated Cholangitis From Primary Sclerosing Cholangitis or Cholangiocarcinoma

Evangelos Kalaitzakis; Michael J. Levy; Terumi Kamisawa; Gavin J. Johnson; Todd H. Baron; Mark Topazian; Naoki Takahashi; Atsushi Kanno; Kazuichi Okazaki; Naoto Egawa; Kazushige Uchida; Kashif Sheikh; Zahir Amin; Tooru Shimosegawa; Neomal S. Sandanayake; Nicholas I. Church; Michael H. Chapman; Stephen P. Pereira; Suresh T. Chari; George Webster

BACKGROUND & AIMS Distinction of immunoglobulin G4-associated cholangitis (IAC) from primary sclerosing cholangitis (PSC) or cholangiocarcinoma is challenging. We aimed to assess the performance characteristics of endoscopic retrograde cholangiography (ERC) for the diagnosis of IAC. METHODS Seventeen physicians from centers in the United States, Japan, and the United Kingdom, unaware of clinical data, reviewed 40 preselected ERCs of patients with IAC (n = 20), PSC (n = 10), and cholangiocarcinoma (n = 10). The performance characteristics of ERC for IAC diagnosis as well as the κ statistic for intraobserver and interobserver agreement were calculated. RESULTS The overall specificity, sensitivity, and interobserver agreement for the diagnosis of IAC were 88%, 45%, and 0.18, respectively. Reviewer origin, specialty, or years of experience had no statistically significant effect on reporting success. The overall intraobserver agreement was fair (0.74). The operating characteristics of different ERC features for the diagnosis of IAC were poor. CONCLUSIONS Despite high specificity of ERC for diagnosing IAC, sensitivity is poor, suggesting that many patients with IAC may be misdiagnosed with PSC or cholangiocarcinoma. Additional diagnostic strategies are likely to be vital in distinguishing these diseases.


Lasers in Medical Science | 1993

Interstitial laser photocoagulation: Evaluation of a 1320 nm Nd-YAG and an 805 nm diode laser: the significance of charring and the value of precharring the fibre tip

Zahir Amin; Giovanni A. Buonaccorsi; Timothy N. Mills; Simon A. Harries; W. R. Lees; Stephen G. Bown

Interstitial laser photocoagulation (ILP) is a new percutaneous technique of thermal destruction (necrosis) of deep-seated tumours, using low power laser energy. Our purpose was to investigate: (i) the effects of different laser wavelengths on the extent of thermal damage produced; and (ii) the role of charring around the fibre tip during ILP. Forty-five normal Wistar rats (250–300 g) had ILP to their liver (exposed at laparotomy) by inserting a 400 μm optical fibre into the liver, and activating the laser at 1, 2 or 3W. This was performed at three laser wavelengths (1064 nm Nd-YAG, 1320 nm Nd-YAG, 805 nm diode) using a clean plane-cleaved fibre, and at two wavelengths (1064 nm and 1320 nm Nd-YAG) using a fibre with pre-charring at its tip. The 805 nm and 1320 nm laser wavelengths produced significantly greater necrosis than the 1064 nm, using a clean fibre tip (mean diameters at 2 W were 21.7 mm, 18.3 mm, 8 mm respectively). Pre-charring the fibre significantly increased the necrotic lesion size at 1064 nm (mean diameter at 2 W was 14.7 mm). Using more strongly absorbed wavelengths (805 nm and 1320 nm) and pre-charring the fibre tip give greater thermal damage during ILP, contrary to previously held views that the optimal wavelength for ILP was 1064 nm in the absence of charring.


Annals of Surgery | 2012

Cholangiocarcinoma or IgG4-Associated Cholangitis How Feasible It Is to Avoid Unnecessary Surgical Interventions?

Lytras D; Evangelos Kalaitzakis; George Webster; Charles Imber; Zahir Amin; Manuel Rodriguez-Justo; Stephen P. Pereira; Olde Damink Sw; Malagoʼ M

Objective:To evaluate the experience of a tertiary hepatopancreaticobiliary (HPB) center in the diagnostic approach and management of patients with suspicion of cholangiocarcinoma (CCa), focusing on excluding patients with IgG4-associated cholangitis (IAC) from unnecessary major surgical interventions. Methods:Between January 2008 and September 2010, a total number of 152 patients with suspicion of CCa underwent evaluation through a HPB multidisciplinary team meeting. Patients without tissue diagnosis were managed surgically or medically on the basis of probable presence of IAC as underlying pathology. Serology, immunostaining, and imaging were reviewed and analyzed according to the HISORt (Histology, Imaging, Serology, Other organ involvement, Response to therapy) criteria for IAC. Results:Tissue diagnosis during the diagnostic workup was achieved in 104 patients (68%), whereas the remaining 48 were classified as “highly suspicious for CCa” (n = 35) or as “probable IAC” (n = 13). Among 16 “highly suspicious for CCa” patients who underwent surgery, pathology revealed 2 patients harboring IAC (n = 1) and a benign chronic inflammatory biliary stricture (n = 1), respectively. Among the 13 patients with primarily medical management as “probable IAC,” final diagnosis was CCa (n = 3) and IAC (n = 9), while 1 patient had no proven diagnosis. The accuracy of serum IgG4 for diagnosis of IAC reached 60%. Sensitivity and specificity of immunostaining for IAC in biopsy specimens were 56% and 89%, respectively. Imaging features suggesting IAC yielded sensitivity, specificity, and accuracy of 75%, 89%, and 83%, respectively. Initial imaging was revised at the referral institute in 75% of IAC patients (P = 0.009), while an isolated stricture (P = 0.038), a biliary mass (P = 0.006), and normal pancreas on computed tomography (P = 0.01) were statistically significant parameters for distinguishing between CCa and IAC. The mean time for establishing a diagnosis of IAC was 12.4 months (range: 2.5–32 months) Conclusions:Differential diagnosis between CCa and IAC mandates high index of suspicion and low threshold for referral in high volume institutes. The delayed establishment of diagnosis particularly for CCa needs to be balanced versus avoiding unnecessary surgery for IAC. Imaging features may be most helpful for optimal management.


Leukemia & Lymphoma | 1996

Retinoic Acid Syndrome: Pulmonary Computed Tomography (CT) Findings

Bernard A. Davis; Paul Cervi; Zahir Amin; Grace Moshi; Penny Shaw; John B. Porter

We report the pulmonary computed tomography (CT) findings in three patients with acute promyelocytic leukaemia who developed the retinoic acid syndrome following all-trans retinoic acid (ATRA) therapy. The most consistent CT findings were small, irregular peripheral nodules in the lung fields and pleural effusions. Two of the patients also showed evidence of reticular and ground glass shadowing as well as abnormal anterior mediastinal soft tissue. We report for the first time an association between ATRA and pneumothorax. We conclude that routine CT scanning may provide a sensitive means of early detection or monitoring of the syndrome and thereby may facilitate its management.


Clinical Infectious Diseases | 2015

Current Management of Cystic Echinococcosis: A Survey of Specialist Practice

Laura Nabarro; Zahir Amin; Peter L. Chiodini

BACKGROUND Cystic echinococcosis (CE) is a significant public health problem worldwide. However, there remains a dearth of evidence guiding treatment in various stages of CE. The 2010 World Health Organization (WHO) Informal Working Group on Echinococcosis (WHO IWGE) guidance is thus based on expert consensus rather than a good evidence base. This study aims to describe the way clinicians worldwide manage CE and to establish whether clinicians follow WHO IWGE guidance. METHODS Using the online surveying tool SurveyMonkey, a questionnaire was produced detailing 5 clinical cases. Clinicians treating CE were identified and asked how to manage each case through tick-box and short-answer questions. RESULTS The results showed great variation in practice worldwide. There are practices in common use that are known to be ineffectual, including puncture, aspiration, injection, reaspiration procedures on WHO type 2 cysts, or outdated, including interrupted, rather than continuous, courses of albendazole. A number of unsafe practices were identified such as using scolicidal agents in cysts communicating with the biliary tree and short-course medical therapy for disseminated disease. Most clinicians do not follow the WHO IWGE guidance, but the reasons for this are unclear. CONCLUSIONS Management of CE varies greatly worldwide. There are key areas of CE for which there is no evidence on which to base guidelines, and randomized controlled trials are needed together with a well-designed international registry to collect data. Further work is required to establish why clinicians do not follow the IWGE guidance, together with better dissemination of future guidance.


CardioVascular and Interventional Radiology | 2010

Cystic artery pseudoaneurysms in hemorrhagic acute cholecystitis.

Julian Hague; Duncan Brennand; Jowad Raja; Zahir Amin

Cystic artery pseudoaneurysms (PsA) are, according to the literature, a rare finding, with 14 reported cases in patients who have not undergone a previous cholecystectomy. We have encountered three such cases over a 6-month period, and we propose that wider usage of abdominal computed tomographic (CT) angiography may detect more of these lesions. High-attenuation material in the gallbladder in a patient with hemobilia or hemoperitoneum should prompt the search for a cystic artery PsA, best achieved with triplephase CT (precontrast, arterial phase, and portal venous phase scans). Case 1 An 83-year-old man sought care at the emergency department with a short history of right hypochondrial pain. Arterial phase CT scan showed a small PsA in the wall of the gallbladder with evidence of gallbladder perforation and a moderate-sized hemoperitoneum. Surgical intervention was thought to be extremely hazardous, given the clinical condition of the patient. The presence of a PsA was confirmed at angiography by occlusion achieved with superselective cannulation of the cystic artery using a 4F Simmonds 1 catheter (Cordis, Miami, FL) and a 2.7F Progreat microcatheter (Terumo, Tokyo) and by the

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George Webster

University College London

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Michael H. Chapman

University College London Hospitals NHS Foundation Trust

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Nicholas I. Church

University College Hospital

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Stephen G. Bown

University College London

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William R. Lees

University College London

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Adrian R. Hatfield

University College Hospital

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Evangelos Kalaitzakis

Copenhagen University Hospital

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