Many astrophysical objects (e.g., spiral galaxies, the solar system, Saturn's rings, and luminous... more Many astrophysical objects (e.g., spiral galaxies, the solar system, Saturn's rings, and luminous disks around compact objects) occur in the form of a disk. One of the important astrophysical problems is to understand how rotationally supported disks lose angular momentum, and accrete towards the bottom of the gravitational potential, converting gravitational energy into thermal (and radiation) energy. The magnetorotational instability (MRI), an instability causing turbulent trans-I foremost thank my adviser Greg Hammett, whose guidance made this thesis possible. His insight, quest for perfection, and passion for science has always inspired me. He was always patient, and ensured that I understood every subtle point. Thanks to Eliot Quataert, who is an inspiring mentor, and initiated me into the fascinating field of astrophysics. He was so accessible that I never felt that he was not in Princeton. I am thankful to Jim Stone for his constant encouragement, and help with numerical methods, especially ZEUS. Finally, thanks to my loving and supporting family, and wonderful friends. Special thanks to my brother Rohit, sister Chubi, and cousins, who have always brought joy in my life. My wife Asha has been a loving and caring companion; her suggestion to keep it simple has significantly improved the thesis.
2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012
We describe and demonstrate for the first time the use of the novel Multiple Module Multiplexer (... more We describe and demonstrate for the first time the use of the novel Multiple Module Multiplexer (MMMIC) for a 2×2 array of new electron multiplying charge coupled device (EMCCD) based x-ray detectors. It is highly desirable for x-ray imaging systems to have larger fields of view (FOV) extensible in two directions yet to still be capable of doing high resolution imaging over regions-of-interest (ROI). The MMMIC achieves these goals by acquiring and multiplexing data from an array of imaging modules thereby enabling a larger FOV, and at the same time allowing high resolution ROI imaging through selection of a subset of modules in the array. MMMIC also supports different binning modes. This paper describes how a specific two stage configuration connecting three identical MMMICs is used to acquire and multiplex data from a 2×2 array of EMCCD based detectors. The first stage contains two MMMICs wherein each MMMIC is getting data from two EMCCD detectors. The multiplexed data from these MMMICs is then forwarded to the second stage MMMIC in the similar fashion. The second stage that has only one MMMIC gives the final 12 bit multiplexed data from four modules. This data is then sent over a high speed Camera Link interface to the image processing computer. X-ray images taken through the 2×2 array of EMCCD based detectors using this two stage configuration of MMMICs are shown successfully demonstrating the concept.
Inflammation & intestinal metaplasia in the gastric cardia of patients presenting for upper e... more Inflammation & intestinal metaplasia in the gastric cardia of patients presenting for upper endoscopy
Lugols chromoendoscopy has been used at our medical center in prospective study protocols involvi... more Lugols chromoendoscopy has been used at our medical center in prospective study protocols involving the thermal ablation of BE or BE complicated by dysplasia or early cancer. Lugols was used during ablation cases either: 1) at the start of the case to better delineate residual columnar tissue from neosquamous tissue at scheduled follow up ablation visits, and/or 2) at end of each ablation session after all visible columnar tissue had been treated in order to detect any residual islands/patches of untreated, previously unrecognized columnar tissue. Details of each ablation case were recorded prospectively. All ablation sessions were performed with Olympus video endoscopy equipment (GIF-1T100 or GIF-2T100). Lugols iodine (15% to 30% solution) was sprayed with either an Olympus PW-5L or Wilson-Cook GT-7 spray catheter. Results: Over a 24 month period 24 BE pts have entered into thermal ablation protocols. Lugols was used in 20/24 pts. In these 20 pts, 58 ablation sessions have been performed, 52 (89.7%) in which Lugols was used. Lugols was used to better delineate residual BE tissue from squamous/neosquamous tissue in 17.3% (9/52) cases. In 82.7% (43/52) of cases it was used at the end of the ablation session to uncover unsuspected residual foci of columnar tissue-48.9% (21/43) of which one or more islands/patches of untreated tissue were found, leading to further targeted ablation treatments. Conclusions: Lugols chromoendoscopy is a valuable tool during ablation of BE as it frequently uncovers unsuspected, untreated foci of columnar tissue not apparent with standard video endoscopy. In addition, in about 1/5th of ablation cases it is required to clarify the blurred squamous-gastric interface. Use of Lugols iodine in BE ablation protocols may help in reducing the incidence of residual foci of columnar tissue reported on post "complete" ablation surveillance endoscopies. 107 Prospective evaluation of the role of H. pylori and progression of Barretts esophagus to adenocarcinoma or multifocal high-grade dysplasia (mHGD)
The extent of reduction of esophageal adenocarcinoma (EAC) incidence in Barrett's esophagus (... more The extent of reduction of esophageal adenocarcinoma (EAC) incidence in Barrett's esophagus (BE) patients after endoscopic ablation is not known. The objective of this study was to determine the cancer incidence in BE patients after ablative therapy and compare these rates to cohort studies of BE patients not undergoing ablation. A MEDLINE search of the literature on the natural history and ablative modalities in BE patients was performed. Patients with nondysplastic BE (NDBE), low-grade dysplasia (LGD), or high-grade dysplasia (HGD) and follow-up of at least 6 months were included. The rate of cancer in patients undergoing ablation and from the natural history data was calculated using weighted-average incidence rates (WIR). A total of 53 articles met the inclusion criteria for the natural history data. Pooled natural history data showed cancer incidence of 5.98/1,000 patient-years (95% CI 5.05-6.91) in NDBE; 16.98/1,000 patient-years (95% CI 13.1-20.85) in LGD; and 65.8/1,000 ...
Barrett's oesophagus is the most important and recognizable precursor lesion for oesophageal ... more Barrett's oesophagus is the most important and recognizable precursor lesion for oesophageal adenocarcinoma, which is the one of the fastest growing cancers in the Western World. The incidence of oesophageal adenocarcinoma has increased 600% in the United States between 1975 and 2001 and is thought to represent a real increase in burden rather than a result of histologic or anatomical misclassification or overdiagnosis. Thus, the cancer risk in Barrett's oesophagus has to be managed and involves prevention (surveillance endoscopy), treating underlying gastroesophageal reflux disease (medically and or surgically) and endoscopic therapy to remove diseased epithelium in appropriate patient subgroups. In the last decade, new developments in imaging and molecular markers as well as an armamentarium of novel and effective endoscopic eradication therapy has become available to the endoscopist to combat this exponential rise in oesophageal adenocarcinoma. Paradoxically, the cancer r...
Gastroesophageal reflux disease (GERD) is a common chronic disorder that is associated with a hug... more Gastroesophageal reflux disease (GERD) is a common chronic disorder that is associated with a huge economic burden in the western countries and significantly decreased quality of life. This review focuses on the various multicultural issues in the epidemiology, pathophysiology, diagnosis, and treatment of GERD. The prevalence of GERD appears to be highest in North America and Europe, whereas epidemiologic data from the Indian subcontinent, Africa, South America, and the Middle East are sparse. A limited number of studies have elucidated ethnic differences in GERD in multiracial populations. African Americans and Asians appear to be at a lower risk for the development of complicated GERD including Barrett's esophagus (BE). Whether the pathophysiology of GERD differs among different populations remains to be answered satisfactorily. It appears that most of the factors involved in the pathogenesis of GERD, as described in western populations, are present in Asians but at a lower scale. The current recommendations for the management of GERD by the American College of Gastroenterology may not meet the need for different ethnic groups or for different geographic regions. Recognition of language barriers in understanding the common terms used to describe reflux symptoms should be borne in mind while treating GERD patients with different ethnic backgrounds. In addition, a universally accepted definition for treatment success in GERD patients is lacking. Given the negative impact on health-related quality of life, significant cost ramifications, and increased risk for BE and esophageal adenocarcinoma, the study of multicultural issues in GERD should be considered.
gastroenterologists suggests that the third party payers regularly provide reimbursement for a sc... more gastroenterologists suggests that the third party payers regularly provide reimbursement for a screening endoscopy. Recent developments in the area of primary prophylaxis of variceal bleeding deserve mention. Recent data suggest that ultrathin endoscopes (transnasal or peroral) could be used for screening varices in unsedated cirrhotics (5). This technology presents the possibility of endoscopic screening for varices in the office setting, enhancing the feasibility and probably reducing costs. Furthermore, several investigators have shown that readily available clinical variables predict the presence of large esophageal varices (6-8). Our group has shown that a "clinical decision aid" comprising two variables (splenomegaly and thrombocytopenia) stratifies the risk for large esophageal varices and may be costeffective (6). On the treatment end, recent data suggest that prophylactic ligation reduces the risks of variceal bleeding and mortality as compared to "no treatment" and reduces the risk for first variceal bleed as compared to -blockers (9). Preliminary studies suggest that newer agents such as carvedilol (a nonselective -blocker with intrinsic anti-␣ 1-adrenergic activity) and losartan (angiotensin-II receptor antagonist) reduce portal pressure to a greater extent than the -blockers (10, 11). These developments are likely to improve the feasibility of detecting large esophageal varices and of instituting measures for primary prophylaxis. The findings by Arguedas et al. need to be confirmed and extended to explore the reasons for nonadherence to published guidelines, and more research needs to be done to establish the cost-effectiveness of endoscopic variceal screening. Furthermore, it is important to provide continued exposure to the guidelines through educational efforts. It is possible that ongoing research, such as the multicenter study of timolol to prevent the development of varices and the evaluation of variceal ligation for primary prevention, may result in modification of these guidelines. Meanwhile, it is essential that all of us who care for patients with cirrhosis adhere to the published guidelines for primary prophylaxis of variceal bleeding, beginning with endoscopic screening for their detection.
The study focuses on the assessment of inherent vulnerability of rural communities in Kimsar regi... more The study focuses on the assessment of inherent vulnerability of rural communities in Kimsar region to environmental hazards. A new conceptual framework was developed and hazard generic socioeconomic indicators were identified in the assessment of inherent vulnerability of the communities to future harm. All the households from the selected villages were surveyed to collect information on the identified indicators. These indicators captured eight sub-components of inherent vulnerability, which includes lack of access to water, shelter, information, and connectivity, economic capacity, dependence on environmental resources, marginalised communities and gender. An Inherent Vulnerability Score (IVS) was computed, for each of the twelve villages by aggregating the data into a composite score. Sensitivity analysis was conducted for the composite score. The results obtained from a cluster analysis on the same village-level data were consistent with the IVS. Based on the results of cluster analysis, the villages were classified into three vulnerability groups ─ high, moderate and low. Access to water, dependence on environmental resources and shelter were found to be the most important determinants of inherent vulnerability in the region. Knowledge of Contents lists available at ScienceDirect
The rising incidence of adenocarcinoma of the esophagus and the gastric cardia has generated inte... more The rising incidence of adenocarcinoma of the esophagus and the gastric cardia has generated interest in the finding of intestinal metaplasia or specialized columnar mucosa in this location. Short segment Barrett esophagus is defined by the presence of columnar-appearing mucosa in the distal esophagus (<3 cm in length) with intestinal metaplasia on biopsy. In contrast, intestinal metaplasia may also be present if biopsy specimens are obtained from a normal-appearing squamocolumnar junction or from the gastric cardia (ie, immediately below the gastroesophageal junction) in the absence of columnar lining of the distal esophagus. This has been termed cardia intestinal metaplasia, gastroesophageal junction intestinal metaplasia, or specialized columnar mucosa at the gastroesophageal junction. This article reviews the currently available data on these rapidly evolving entities of short segment Barrett esophagus and specialized columnar mucosa at the gastroesophageal junction.
Background: With the advent of multiple novel techniques, optimal methods to teach advanced imagi... more Background: With the advent of multiple novel techniques, optimal methods to teach advanced imaging techniques like pCLE have not yet been developed. There are limited data regarding the learning curve for trainees for using pCLE in diagnosing BE associated neoplasia. Aim: To determine the learning curve of medical trainees in diagnosing BE associated neoplasia using pCLE. Methods: Videos from a previously conducted multicenter trial evaluating the utility of pCLE in BE were used for this study. Study participants (GI fellows and medical students) with no previous pCLE experience were randomized to either in-class didactic or selfdirected teaching groups stratified by level of training. A standardized power point presentation was developed explaining the technology, the disease state and using previously published validated criteria for diagnosing dysplasia in BE: 1)epithelial surface: saw-toothed 2)goblet cells: sparse 3)glands: not equidistant 4)glands: unequal in size and shape 5)cells: enlarged 6)cells: pleomorphic. For in-class didactic group, an expert in pCLE conducted a classroom teaching session with an opportunity for interaction. Every study participant in the self-directed teaching group was provided with the same teaching power point but with recorded audio explaining the pCLE features to distinguish dysplastic and non-dysplastic BE. Following this initial training, all participants completed 1st set of 20 pCLE videos (pre-feedback) after which they reviewed correct responses with either the expert (in-class didactic group) or on audio power point (self teaching group). Finally, all participants completed next set of 40 videos (post-feedback) and marked their level of confidence in video interpretation for all assessments. Fisher's exact test was used to calculate statistical differences between groups. Results:60 pCLE videos (nondysplastic BE 40 and dysplastic 20) were assessed by 18 study participants (10 GI fellows and 8 students). The overall accuracy of the entire group significantly improved from 73% to 79% post feedback (p Z0.04) (Table). This improvement was driven by overall improvement post feedback for the in-class didactic group (from 74% to 84%; p !0.01). Students had improvement in the proportion of predictions with high confidence (from 47% to 54.4% p 0.1) while fellows improved their pCLE accuracy in high-confidence predictions (from 82% to 91%, p 0.02) (Table). Finally, accuracy improved with years in endoscopy training (72.08% Students, 77.08% FY1, 82% FY2 and 85% FY3, p 0.003). Conclusions: Trainees taught by an in-class, didactic teaching session (overall 1 hour) had a shorter learning curve and achieved higher accuracies compared to self-directed learning group for the use of pCLE to diagnose BE associated neoplasia. In-class didactic teaching sessions should be the preferred method to teach pCLE for use in BE.
Background: Radiofrequency ablation (RFA) has been shown to completely eradicate dysplastic intes... more Background: Radiofrequency ablation (RFA) has been shown to completely eradicate dysplastic intestinal metaplasia (IM) in most patients, yet residual IM may persist in some. Aims: The primary endpoint for RFA therapy is complete response-IM (CR-IM, no histological evidence of IM). We sought to describe pt characteristics related to incomplete response-IM (IR-IM, any residual IM). We also assessed dysplasia grade, and extent/location of any residual IM. Methods: We enrolled 127 pts with dysplastic BE (63 HGD, 64 LGD) in a multi-center trial of RFA. Pts were randomized 2:1 (RFA vs. sham) then biopsied q 3 or 6 mo, with centralized path review. RFA was performed until CR-IM or max 4 sessions.
Gastrointestinal Endoscopy, Volume 71, Issue 5, Pages AB203, April 2010, Authors:Raymond E. Kim; ... more Gastrointestinal Endoscopy, Volume 71, Issue 5, Pages AB203, April 2010, Authors:Raymond E. Kim; Vikas Singh; Sandra B. Hall; Mandeep Singh; Amit Rastogi; Brian Moloney; Sachin B. Wani; Srinivas Gaddam; Sharad C. Mathur; Michael B. Wallace; Prateek Sharma; Ajay ...
Surveillance of patients with Barrett's esophagus is undertaken for the detection of dysplasi... more Surveillance of patients with Barrett's esophagus is undertaken for the detection of dysplasia and adenocarcinoma. This involves obtaining random biopsies from the entire Barrett's segment. The preferential location of dysplasia/cancer either proximally or distally within the Barrett's segment in not clear and if clarified may assist in surveillance programs. Aim: To determine the location of dysplasia/cancer in patients with Barrett's esophagus. Methods: Patients with Barrett's esophagus (2=:3cms length) diagnosed with low grade dysplasia (LGD), high grade dysplasia (HGD) or cancer (CA) were identified from a well defined prospectively followed group of patients with Barrett's esophagus all having undegone a similar biopsy protocol-4 quadrant, every -2 cms. The location of biopsies revealing dysplasia/cancer in these patients was classified as proximal/distalif dysplasia/cancer were diagnosed in biopsy specimens from both proximal & distal Barrett's segments; distal only -dysplasia/cancer only in the distal biopsy specimens; proximal only -dysplasia/cancer only in the proximal biopsy specimens. The patient demographics and the length of Barrett's were also recorded. Results: Sixty-five patients (all white males) with Barrett's esophagus and LGD,HGD,and/or CA were studied; mean age 61.4 years (range:30-80 yrs), mean Barrett's length 7.7 ems (range:3-19 cms) These patients have undergone a total of 198 EGDlbx sessions revealing dysplasia/cancer. Location of dysplasia/cancer is as follows (table): Conclusions: Dysplasia, including HGD and CA is distributed throughout the entire length of the segment (ie.both proximally & distally) in more than half of patients with dysplasia/cancer within Barrett's esophagus thus necessitating the need for surveillance biopsies from the entire Barrett's esophagus. The concept that cancer occurs distally in patients with Barrett's esophagus is probably incorrect.
Many astrophysical objects (e.g., spiral galaxies, the solar system, Saturn's rings, and luminous... more Many astrophysical objects (e.g., spiral galaxies, the solar system, Saturn's rings, and luminous disks around compact objects) occur in the form of a disk. One of the important astrophysical problems is to understand how rotationally supported disks lose angular momentum, and accrete towards the bottom of the gravitational potential, converting gravitational energy into thermal (and radiation) energy. The magnetorotational instability (MRI), an instability causing turbulent trans-I foremost thank my adviser Greg Hammett, whose guidance made this thesis possible. His insight, quest for perfection, and passion for science has always inspired me. He was always patient, and ensured that I understood every subtle point. Thanks to Eliot Quataert, who is an inspiring mentor, and initiated me into the fascinating field of astrophysics. He was so accessible that I never felt that he was not in Princeton. I am thankful to Jim Stone for his constant encouragement, and help with numerical methods, especially ZEUS. Finally, thanks to my loving and supporting family, and wonderful friends. Special thanks to my brother Rohit, sister Chubi, and cousins, who have always brought joy in my life. My wife Asha has been a loving and caring companion; her suggestion to keep it simple has significantly improved the thesis.
2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012
We describe and demonstrate for the first time the use of the novel Multiple Module Multiplexer (... more We describe and demonstrate for the first time the use of the novel Multiple Module Multiplexer (MMMIC) for a 2×2 array of new electron multiplying charge coupled device (EMCCD) based x-ray detectors. It is highly desirable for x-ray imaging systems to have larger fields of view (FOV) extensible in two directions yet to still be capable of doing high resolution imaging over regions-of-interest (ROI). The MMMIC achieves these goals by acquiring and multiplexing data from an array of imaging modules thereby enabling a larger FOV, and at the same time allowing high resolution ROI imaging through selection of a subset of modules in the array. MMMIC also supports different binning modes. This paper describes how a specific two stage configuration connecting three identical MMMICs is used to acquire and multiplex data from a 2×2 array of EMCCD based detectors. The first stage contains two MMMICs wherein each MMMIC is getting data from two EMCCD detectors. The multiplexed data from these MMMICs is then forwarded to the second stage MMMIC in the similar fashion. The second stage that has only one MMMIC gives the final 12 bit multiplexed data from four modules. This data is then sent over a high speed Camera Link interface to the image processing computer. X-ray images taken through the 2×2 array of EMCCD based detectors using this two stage configuration of MMMICs are shown successfully demonstrating the concept.
Inflammation & intestinal metaplasia in the gastric cardia of patients presenting for upper e... more Inflammation & intestinal metaplasia in the gastric cardia of patients presenting for upper endoscopy
Lugols chromoendoscopy has been used at our medical center in prospective study protocols involvi... more Lugols chromoendoscopy has been used at our medical center in prospective study protocols involving the thermal ablation of BE or BE complicated by dysplasia or early cancer. Lugols was used during ablation cases either: 1) at the start of the case to better delineate residual columnar tissue from neosquamous tissue at scheduled follow up ablation visits, and/or 2) at end of each ablation session after all visible columnar tissue had been treated in order to detect any residual islands/patches of untreated, previously unrecognized columnar tissue. Details of each ablation case were recorded prospectively. All ablation sessions were performed with Olympus video endoscopy equipment (GIF-1T100 or GIF-2T100). Lugols iodine (15% to 30% solution) was sprayed with either an Olympus PW-5L or Wilson-Cook GT-7 spray catheter. Results: Over a 24 month period 24 BE pts have entered into thermal ablation protocols. Lugols was used in 20/24 pts. In these 20 pts, 58 ablation sessions have been performed, 52 (89.7%) in which Lugols was used. Lugols was used to better delineate residual BE tissue from squamous/neosquamous tissue in 17.3% (9/52) cases. In 82.7% (43/52) of cases it was used at the end of the ablation session to uncover unsuspected residual foci of columnar tissue-48.9% (21/43) of which one or more islands/patches of untreated tissue were found, leading to further targeted ablation treatments. Conclusions: Lugols chromoendoscopy is a valuable tool during ablation of BE as it frequently uncovers unsuspected, untreated foci of columnar tissue not apparent with standard video endoscopy. In addition, in about 1/5th of ablation cases it is required to clarify the blurred squamous-gastric interface. Use of Lugols iodine in BE ablation protocols may help in reducing the incidence of residual foci of columnar tissue reported on post "complete" ablation surveillance endoscopies. 107 Prospective evaluation of the role of H. pylori and progression of Barretts esophagus to adenocarcinoma or multifocal high-grade dysplasia (mHGD)
The extent of reduction of esophageal adenocarcinoma (EAC) incidence in Barrett's esophagus (... more The extent of reduction of esophageal adenocarcinoma (EAC) incidence in Barrett's esophagus (BE) patients after endoscopic ablation is not known. The objective of this study was to determine the cancer incidence in BE patients after ablative therapy and compare these rates to cohort studies of BE patients not undergoing ablation. A MEDLINE search of the literature on the natural history and ablative modalities in BE patients was performed. Patients with nondysplastic BE (NDBE), low-grade dysplasia (LGD), or high-grade dysplasia (HGD) and follow-up of at least 6 months were included. The rate of cancer in patients undergoing ablation and from the natural history data was calculated using weighted-average incidence rates (WIR). A total of 53 articles met the inclusion criteria for the natural history data. Pooled natural history data showed cancer incidence of 5.98/1,000 patient-years (95% CI 5.05-6.91) in NDBE; 16.98/1,000 patient-years (95% CI 13.1-20.85) in LGD; and 65.8/1,000 ...
Barrett's oesophagus is the most important and recognizable precursor lesion for oesophageal ... more Barrett's oesophagus is the most important and recognizable precursor lesion for oesophageal adenocarcinoma, which is the one of the fastest growing cancers in the Western World. The incidence of oesophageal adenocarcinoma has increased 600% in the United States between 1975 and 2001 and is thought to represent a real increase in burden rather than a result of histologic or anatomical misclassification or overdiagnosis. Thus, the cancer risk in Barrett's oesophagus has to be managed and involves prevention (surveillance endoscopy), treating underlying gastroesophageal reflux disease (medically and or surgically) and endoscopic therapy to remove diseased epithelium in appropriate patient subgroups. In the last decade, new developments in imaging and molecular markers as well as an armamentarium of novel and effective endoscopic eradication therapy has become available to the endoscopist to combat this exponential rise in oesophageal adenocarcinoma. Paradoxically, the cancer r...
Gastroesophageal reflux disease (GERD) is a common chronic disorder that is associated with a hug... more Gastroesophageal reflux disease (GERD) is a common chronic disorder that is associated with a huge economic burden in the western countries and significantly decreased quality of life. This review focuses on the various multicultural issues in the epidemiology, pathophysiology, diagnosis, and treatment of GERD. The prevalence of GERD appears to be highest in North America and Europe, whereas epidemiologic data from the Indian subcontinent, Africa, South America, and the Middle East are sparse. A limited number of studies have elucidated ethnic differences in GERD in multiracial populations. African Americans and Asians appear to be at a lower risk for the development of complicated GERD including Barrett's esophagus (BE). Whether the pathophysiology of GERD differs among different populations remains to be answered satisfactorily. It appears that most of the factors involved in the pathogenesis of GERD, as described in western populations, are present in Asians but at a lower scale. The current recommendations for the management of GERD by the American College of Gastroenterology may not meet the need for different ethnic groups or for different geographic regions. Recognition of language barriers in understanding the common terms used to describe reflux symptoms should be borne in mind while treating GERD patients with different ethnic backgrounds. In addition, a universally accepted definition for treatment success in GERD patients is lacking. Given the negative impact on health-related quality of life, significant cost ramifications, and increased risk for BE and esophageal adenocarcinoma, the study of multicultural issues in GERD should be considered.
gastroenterologists suggests that the third party payers regularly provide reimbursement for a sc... more gastroenterologists suggests that the third party payers regularly provide reimbursement for a screening endoscopy. Recent developments in the area of primary prophylaxis of variceal bleeding deserve mention. Recent data suggest that ultrathin endoscopes (transnasal or peroral) could be used for screening varices in unsedated cirrhotics (5). This technology presents the possibility of endoscopic screening for varices in the office setting, enhancing the feasibility and probably reducing costs. Furthermore, several investigators have shown that readily available clinical variables predict the presence of large esophageal varices (6-8). Our group has shown that a "clinical decision aid" comprising two variables (splenomegaly and thrombocytopenia) stratifies the risk for large esophageal varices and may be costeffective (6). On the treatment end, recent data suggest that prophylactic ligation reduces the risks of variceal bleeding and mortality as compared to "no treatment" and reduces the risk for first variceal bleed as compared to -blockers (9). Preliminary studies suggest that newer agents such as carvedilol (a nonselective -blocker with intrinsic anti-␣ 1-adrenergic activity) and losartan (angiotensin-II receptor antagonist) reduce portal pressure to a greater extent than the -blockers (10, 11). These developments are likely to improve the feasibility of detecting large esophageal varices and of instituting measures for primary prophylaxis. The findings by Arguedas et al. need to be confirmed and extended to explore the reasons for nonadherence to published guidelines, and more research needs to be done to establish the cost-effectiveness of endoscopic variceal screening. Furthermore, it is important to provide continued exposure to the guidelines through educational efforts. It is possible that ongoing research, such as the multicenter study of timolol to prevent the development of varices and the evaluation of variceal ligation for primary prevention, may result in modification of these guidelines. Meanwhile, it is essential that all of us who care for patients with cirrhosis adhere to the published guidelines for primary prophylaxis of variceal bleeding, beginning with endoscopic screening for their detection.
The study focuses on the assessment of inherent vulnerability of rural communities in Kimsar regi... more The study focuses on the assessment of inherent vulnerability of rural communities in Kimsar region to environmental hazards. A new conceptual framework was developed and hazard generic socioeconomic indicators were identified in the assessment of inherent vulnerability of the communities to future harm. All the households from the selected villages were surveyed to collect information on the identified indicators. These indicators captured eight sub-components of inherent vulnerability, which includes lack of access to water, shelter, information, and connectivity, economic capacity, dependence on environmental resources, marginalised communities and gender. An Inherent Vulnerability Score (IVS) was computed, for each of the twelve villages by aggregating the data into a composite score. Sensitivity analysis was conducted for the composite score. The results obtained from a cluster analysis on the same village-level data were consistent with the IVS. Based on the results of cluster analysis, the villages were classified into three vulnerability groups ─ high, moderate and low. Access to water, dependence on environmental resources and shelter were found to be the most important determinants of inherent vulnerability in the region. Knowledge of Contents lists available at ScienceDirect
The rising incidence of adenocarcinoma of the esophagus and the gastric cardia has generated inte... more The rising incidence of adenocarcinoma of the esophagus and the gastric cardia has generated interest in the finding of intestinal metaplasia or specialized columnar mucosa in this location. Short segment Barrett esophagus is defined by the presence of columnar-appearing mucosa in the distal esophagus (<3 cm in length) with intestinal metaplasia on biopsy. In contrast, intestinal metaplasia may also be present if biopsy specimens are obtained from a normal-appearing squamocolumnar junction or from the gastric cardia (ie, immediately below the gastroesophageal junction) in the absence of columnar lining of the distal esophagus. This has been termed cardia intestinal metaplasia, gastroesophageal junction intestinal metaplasia, or specialized columnar mucosa at the gastroesophageal junction. This article reviews the currently available data on these rapidly evolving entities of short segment Barrett esophagus and specialized columnar mucosa at the gastroesophageal junction.
Background: With the advent of multiple novel techniques, optimal methods to teach advanced imagi... more Background: With the advent of multiple novel techniques, optimal methods to teach advanced imaging techniques like pCLE have not yet been developed. There are limited data regarding the learning curve for trainees for using pCLE in diagnosing BE associated neoplasia. Aim: To determine the learning curve of medical trainees in diagnosing BE associated neoplasia using pCLE. Methods: Videos from a previously conducted multicenter trial evaluating the utility of pCLE in BE were used for this study. Study participants (GI fellows and medical students) with no previous pCLE experience were randomized to either in-class didactic or selfdirected teaching groups stratified by level of training. A standardized power point presentation was developed explaining the technology, the disease state and using previously published validated criteria for diagnosing dysplasia in BE: 1)epithelial surface: saw-toothed 2)goblet cells: sparse 3)glands: not equidistant 4)glands: unequal in size and shape 5)cells: enlarged 6)cells: pleomorphic. For in-class didactic group, an expert in pCLE conducted a classroom teaching session with an opportunity for interaction. Every study participant in the self-directed teaching group was provided with the same teaching power point but with recorded audio explaining the pCLE features to distinguish dysplastic and non-dysplastic BE. Following this initial training, all participants completed 1st set of 20 pCLE videos (pre-feedback) after which they reviewed correct responses with either the expert (in-class didactic group) or on audio power point (self teaching group). Finally, all participants completed next set of 40 videos (post-feedback) and marked their level of confidence in video interpretation for all assessments. Fisher's exact test was used to calculate statistical differences between groups. Results:60 pCLE videos (nondysplastic BE 40 and dysplastic 20) were assessed by 18 study participants (10 GI fellows and 8 students). The overall accuracy of the entire group significantly improved from 73% to 79% post feedback (p Z0.04) (Table). This improvement was driven by overall improvement post feedback for the in-class didactic group (from 74% to 84%; p !0.01). Students had improvement in the proportion of predictions with high confidence (from 47% to 54.4% p 0.1) while fellows improved their pCLE accuracy in high-confidence predictions (from 82% to 91%, p 0.02) (Table). Finally, accuracy improved with years in endoscopy training (72.08% Students, 77.08% FY1, 82% FY2 and 85% FY3, p 0.003). Conclusions: Trainees taught by an in-class, didactic teaching session (overall 1 hour) had a shorter learning curve and achieved higher accuracies compared to self-directed learning group for the use of pCLE to diagnose BE associated neoplasia. In-class didactic teaching sessions should be the preferred method to teach pCLE for use in BE.
Background: Radiofrequency ablation (RFA) has been shown to completely eradicate dysplastic intes... more Background: Radiofrequency ablation (RFA) has been shown to completely eradicate dysplastic intestinal metaplasia (IM) in most patients, yet residual IM may persist in some. Aims: The primary endpoint for RFA therapy is complete response-IM (CR-IM, no histological evidence of IM). We sought to describe pt characteristics related to incomplete response-IM (IR-IM, any residual IM). We also assessed dysplasia grade, and extent/location of any residual IM. Methods: We enrolled 127 pts with dysplastic BE (63 HGD, 64 LGD) in a multi-center trial of RFA. Pts were randomized 2:1 (RFA vs. sham) then biopsied q 3 or 6 mo, with centralized path review. RFA was performed until CR-IM or max 4 sessions.
Gastrointestinal Endoscopy, Volume 71, Issue 5, Pages AB203, April 2010, Authors:Raymond E. Kim; ... more Gastrointestinal Endoscopy, Volume 71, Issue 5, Pages AB203, April 2010, Authors:Raymond E. Kim; Vikas Singh; Sandra B. Hall; Mandeep Singh; Amit Rastogi; Brian Moloney; Sachin B. Wani; Srinivas Gaddam; Sharad C. Mathur; Michael B. Wallace; Prateek Sharma; Ajay ...
Surveillance of patients with Barrett's esophagus is undertaken for the detection of dysplasi... more Surveillance of patients with Barrett's esophagus is undertaken for the detection of dysplasia and adenocarcinoma. This involves obtaining random biopsies from the entire Barrett's segment. The preferential location of dysplasia/cancer either proximally or distally within the Barrett's segment in not clear and if clarified may assist in surveillance programs. Aim: To determine the location of dysplasia/cancer in patients with Barrett's esophagus. Methods: Patients with Barrett's esophagus (2=:3cms length) diagnosed with low grade dysplasia (LGD), high grade dysplasia (HGD) or cancer (CA) were identified from a well defined prospectively followed group of patients with Barrett's esophagus all having undegone a similar biopsy protocol-4 quadrant, every -2 cms. The location of biopsies revealing dysplasia/cancer in these patients was classified as proximal/distalif dysplasia/cancer were diagnosed in biopsy specimens from both proximal & distal Barrett's segments; distal only -dysplasia/cancer only in the distal biopsy specimens; proximal only -dysplasia/cancer only in the proximal biopsy specimens. The patient demographics and the length of Barrett's were also recorded. Results: Sixty-five patients (all white males) with Barrett's esophagus and LGD,HGD,and/or CA were studied; mean age 61.4 years (range:30-80 yrs), mean Barrett's length 7.7 ems (range:3-19 cms) These patients have undergone a total of 198 EGDlbx sessions revealing dysplasia/cancer. Location of dysplasia/cancer is as follows (table): Conclusions: Dysplasia, including HGD and CA is distributed throughout the entire length of the segment (ie.both proximally & distally) in more than half of patients with dysplasia/cancer within Barrett's esophagus thus necessitating the need for surveillance biopsies from the entire Barrett's esophagus. The concept that cancer occurs distally in patients with Barrett's esophagus is probably incorrect.
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Papers by Prateek Sharma