Daniel S. Camara

Durability and Predictors of Successful Radiofrequency Ablation for Barrett's Esophagus

BACKGROUND & AIMS After radiofrequency ablation (RFA), patients may experience recurrence of Barretts esophagus (BE) after complete eradication of intestinal metaplasia (CEIM). Rates and predictors of recurrence after successful eradication have been poorly described. METHODS We used the US RFA Registry, a nationwide registry of BE patients receiving RFA, to determine rates and factors that predicted recurrence of intestinal metaplasia (IM). We assessed recurrence by Kaplan-Meier analysis for the overall cohort and by worst pretreatment histology. Characteristics associated with recurrence were included in a logistic regression model to identify independent predictors. RESULTS Among 5521 patients, 3728 had biopsies 12 months or more after initiation of RFA. Of these, 3169 (85%) achieved CEIM, and 1634 (30%) met inclusion criteria. The average follow-up period was 2.4 years after CEIM. IM recurred in 334 (20%) and was nondysplastic or indefinite for dysplasia in 86% (287 of 334); the average length of recurrent BE was 0.6 cm. In Kaplan-Meier analysis, more advanced pretreatment histology was associated with an increased yearly recurrence rate. Compared with patients without recurrence, patients with recurrence were more likely, based on bivariate analysis, to be older, have longer BE segments, be non-Caucasian, have dysplastic BE before treatment, and require more treatment sessions. In multivariate analysis, the likelihood for recurrence was associated with increasing age and BE length, and non-Caucasian race. CONCLUSIONS BE recurred in 20% of patients followed up for an average of 2.4 years after CEIM. Most recurrences were short segments and were nondysplastic or indefinite for dysplasia. Older age, non-Caucasian race, and increasing length of BE length were all risk factors. These risk factors should be considered when planning post-RFA surveillance intervals.

Intestinal endotoxins as co-factors in liver injury.

The interaction between sinusoidal cells of the liver and endotoxins absorbed from the gut may be critical in causing liver cell injury due to a variety of toxins. Both fixed liver macrophages, and those recruited during injury may be important to this process either by their inability to detoxify increased amounts of LPS presented from the intestinal track, or because of the release of potent effectors under its influence. Evidence that intestinal endotoxins are an important co-factor in both experimental and clinical liver injury is discussed. Mechanisms responsible for macrophage mediation of endotoxin injury are proposed, and preliminary evidence that tumor necrosis factor levels are elevated in human liver disease is presented.

D-Galactosamine Liver Injury: Absorption of Endotoxin and Protective Effect of Small Bowel and Colon Resection in Rabbits

Abstract D-Galactosamine is an amino sugar with unique hepatotoxic properties in animals. Although the mechanism of liver injury by galactosamine remains controversial, a role for bacterial endotoxin has been suggested. In the present study, using New Zealand rabbits, we show that the significant increase in serum glutamic oxaloacetic transaminase which followed the injection of 4.25 mmole/kg of D-galactosamine was completely prevented in animals subjected to resection of small bowel and colon. Using an immunoradiometric assay specific for E. coli 026 endotoxin we showed that after instillation of 50 mg of E. coli into the colon, serum levels of this endotoxin were higher in the animals injected with galactosamine than the controls injected with saline. However, the differences in endotoxin concentration between the two groups of animals was statistically significant only at 30 and 60 min. The role of endotoxin in the pathogenesis of galactosamine liver injury is reviewed and discussed.

Incidence of Esophageal Adenocarcinoma and Causes of Mortality After Radiofrequency Ablation of Barrett’s Esophagus

BACKGROUND & AIMS Radiofrequency ablation (RFA) is commonly used to treat Barretts esophagus (BE). We assessed the incidence of esophageal adenocarcinoma (EAC) after RFA, factors associated with the development of EAC, and EAC-specific and all-cause mortality. METHODS We collected data for outcomes of patients who underwent RFA for BE from July 2007 through July 2011 from US multicenter RFA Patient Registry. Patients were followed until July 2014. Kaplan-Meier curves of EAC incidence were stratified by baseline histology. Crude EAC incidence and mortality (all-cause and EAC-specific) were calculated, and adjusted all-cause mortality was assessed. Logistic regression models were constructed to assess predictors of EAC and all-cause mortality. RESULTS Among 4982 patients, 100 (2%) developed EAC (7.8/1000 person-years [PY]) and 9 patients (0.2%) died of EAC (0.7/1000 PY) in a mean 2.7 ± 1.6 years. The incidence of EAC in nondysplastic BE was 0.5/1000 PY. Overall, 157 patients (3%) died during follow-up (all-cause mortality, 11.2/1000 PY). On multivariate logistic regression, baseline BE length (odds ratio, 1.1/ cm) and baseline histology (odds ratios, 5.8 and 50.3 for low-grade dysplasia and high-grade dysplasia [HGD] respectively) predicted EAC incidence. Among 9 EAC deaths, 6 (67%) had baseline HGD, and 3 (33%) had baseline intramucosal EAC. The most common causes of death were cardiovascular (15%) and extraesophageal cancers (15%). No deaths were associated with RFA. CONCLUSIONS Based on analysis of a multicenter registry of patients who underwent RFA of BE, less than 1% died from EAC. The incidence of EAC was markedly lower in this study than in other studies of disease progression, with the greatest absolute benefit observed in patients with HGD.

Original ResearchFull Report: Clinical—Alimentary TractIncidence of Esophageal Adenocarcinoma and Causes of Mortality After Radiofrequency Ablation of Barrett’s Esophagus

BACKGROUND & AIMS Radiofrequency ablation (RFA) is commonly used to treat Barretts esophagus (BE). We assessed the incidence of esophageal adenocarcinoma (EAC) after RFA, factors associated with the development of EAC, and EAC-specific and all-cause mortality. METHODS We collected data for outcomes of patients who underwent RFA for BE from July 2007 through July 2011 from US multicenter RFA Patient Registry. Patients were followed until July 2014. Kaplan-Meier curves of EAC incidence were stratified by baseline histology. Crude EAC incidence and mortality (all-cause and EAC-specific) were calculated, and adjusted all-cause mortality was assessed. Logistic regression models were constructed to assess predictors of EAC and all-cause mortality. RESULTS Among 4982 patients, 100 (2%) developed EAC (7.8/1000 person-years [PY]) and 9 patients (0.2%) died of EAC (0.7/1000 PY) in a mean 2.7 ± 1.6 years. The incidence of EAC in nondysplastic BE was 0.5/1000 PY. Overall, 157 patients (3%) died during follow-up (all-cause mortality, 11.2/1000 PY). On multivariate logistic regression, baseline BE length (odds ratio, 1.1/ cm) and baseline histology (odds ratios, 5.8 and 50.3 for low-grade dysplasia and high-grade dysplasia [HGD] respectively) predicted EAC incidence. Among 9 EAC deaths, 6 (67%) had baseline HGD, and 3 (33%) had baseline intramucosal EAC. The most common causes of death were cardiovascular (15%) and extraesophageal cancers (15%). No deaths were associated with RFA. CONCLUSIONS Based on analysis of a multicenter registry of patients who underwent RFA of BE, less than 1% died from EAC. The incidence of EAC was markedly lower in this study than in other studies of disease progression, with the greatest absolute benefit observed in patients with HGD.

Immunoradiometric assay of lipid A: a test for detecting and quantitating endotoxins of various origins

The ability to measure circulating endotoxin in various disease states has been hampered by the lack of a specific and quantitative assay. The test most commonly used has been the Limulus gelation assay, which measures an enzymatic effect of endotoxin rather than the substance itself. Based on a solid-phase immunoradiometric assay previously developed to detect the specific lipopolysaccharide from Escherichia coli 026, a similar assay has been developed for the lipid A moiety of endotoxins. The assay uses rabbit antibodies to lipid A which do not react with ketodeoxyoctonate, myristic or beta-hydroxymyristic acids, and detects lipid A obtained from endotoxins of various origins after acid hydrolysis of lipopolysaccharide. Experiments in rats given exogenous endotoxin suggest that this assay can be useful for quantitation of bacterial endotoxins in serum and for studying the pathophysiology of experimental endotoxemia.

Pharmacokinetics of Methylprednisolone Hemisuccinate and Methylprednisolone in Chronic Liver Disease

The disposition of methylprednisolone (MP) and its prodrug hemisuccinate (MPHS) was assessed in six middle‐aged patients with chronic liver disease (CLD) and compared with six younger, healthy subjects after a single IV dose of 25.4 mg of MPHS. Blood and urine samples were collected over 12 hours. Plasma and urine concentrations of MPHS and MP and plasma cortisol were measured by HPLC. MPHS clearance (CL) was significantly reduced in the CLD group (495 vs. 1389 mL/hr/kg) whereas volume of distribution (Vss) of MPHS (about 0.35 1/kg) did not differ. The elimination half‐life, t1/2β, was significantly longer in CLD (0.61 vs. 0.32 hr). The percent recovery of unchanged MPHS in urine was similar (about 9%) in both groups. The kinetic parameters of MP did not differ between the two groups for: clearance (about 370 L/hr/kg IBW), Vss (about 1.3 L/kg), and t1/2β (about 3.0 hr). The suppression t1/2 of cortisol after MPHS was longer (3.9 vs. 1.9 hr) indicating metabolic pathways for cortisol and MP are affected differently in CLD. Reduction in MPHS CL may reflect altered hepatic blood flow due to both cirrhosis and age effects. However, good availability of MP from MPHS and lack of perturbation of MP pharmacokinetics in CLD patients may provide therapeutic advantages in selection of this glucocorticoid. This is the first study that characterizes the disposition of the prodrug MPHS and the formation of MP simultaneously in CLD patients.

Tu1121 Radiofrequency Ablation (RFA) Safely Treats Barrett's Esophagus in a Nationwide, Multicenter Cohort: Results From the U.S. RFA Registry

G A A b st ra ct s (66%) were diagnosed with OSA and 2,597 (34%) did not have OSA. BE was diagnosed in 339 (7%) subjects with OSA and 113 (4%) subjects without OSA (see Figure 1). Baseline grade of dysplasia in BE subjects was: no dysplasia (280, 81%), LGD (39, 11%) and HGD (25, 7%). Baseline characteristics of cases and controls are displayed in Table 1. Subjects with OSA were found to have an increased risk of having a validated BE diagnosis compared to those without OSA : unadjusted OR 1.6 (95% CI 1.3, 1.99, p value < 0.0001). This increased risk persisted after adjustment for age and gender (OR 1.37 95%CI 1.1, 1.7 p= 0.004). Conclusion: Individuals with OSAmay constitute a higher risk subset for the presence of BE. Prospective studies are needed to confirm this association. The mechanistic links between BE and OSA need to be explored. Table 1: Baseline characteristics of BE cases and controls

Simplified portoazygous disconnection (Tanner's operation) combined with operative sclerotherapy for bleeding varices

A simplified method of portoazygous disconnection employing the linear stapler and operative sclerotherapy was employed in six patients. Endoscopic maintenance sclerotherapy was instituted for five patients in the follow-up period. Combining the operative and endoscopic modalities is attractive, since the deficiencies of each tend to be offset by the other.