Structure of the Mucosal and Stool Microbiome in Lynch Syndrome

The gut microbiota has been associated with colorectal cancer (CRC), but causal alterations preceding CRC have not been elucidated. To prospectively assess microbiome changes prior to colorectal neoplasia, we investigated samples from 100 Lynch syndrome patients using 16S rRNA gene sequencing of colon biopsies, coupled with metagenomic and metatranscriptomic sequencing of feces. Colectomy and CRC history represented the largest effects on microbiome profiles. A subset of Clostridiaceae were depleted in stool corresponding with baseline adenomas, while Desulfovibrio was enriched both in stool and in mucosal biopsies. A classifier leveraging stool metatranscriptomes resulted in modest power to predict interval development of preneoplastic colonic adenoma. Predictive transcripts corresponded with a shift in flagellin contributors and oxidative metabolic microenvironment, potentially factors in local CRC pathogenesis. This suggests that the effectiveness of prospective microbiome monitoring for adenomas may be limited but supports the potential causality of these consistent, early microbial changes in colonic neoplasia.

Radiofrequency ablation for the management of occluded biliary metal stents

Background and study aim: Obstruction of biliary self-expandable metal stents (SEMSs) is seen frequently. Radiofrequency ablation (RFA) causes tissue necrosis. This study aimed to assess the efficacy of RFA for management of occluded SEMS. Patients and methods: Patients with biliary malignancy and treated for an occluded SEMS were retrospectively reviewed. The study group comprised patients treated with RFA using an Habib endoprobe inside the SEMS. The control group comprised patients treated only with insertion of a plastic stent into an occluded SEMS. The end points were; 90-day stent patency rate, time to stent reocclusion, 30-day mortality, and 3 - and 6-month survival rates. Results: During the 5-year study period 25 patients with an occluded SEMS underwent RFA and 25 patients underwent a plastic stent placement only. Both groups were matched for age and diagnosis. Immediate biliary drainage was restored in all patients. In the RFA group, the stenosis was ablated successfully in 14 patients (56 %); ablation failed in 11 and a plastic stent was then inserted into the SEMS for these. The control group had only placement of a plastic stent across the stenosis. Stent patency rate at 90 days was 56 % and 24 % in the RFA and control groups, respectively (P = 0.04). The mean stent patency time was significantly longer in the RFA group compared to the control group (119.5 vs. 65.3 days, P = 0.03). Conclusion: The application of RFA for occluded SEMS improves stent patency. RFA is an alternative treatment of tissue ingrowth in malignant biliary obstruction.

S-nitrosothiol signaling regulates liver development and improves outcome following toxic liver injury

Toxic liver injury is a leading cause of liver failure and death because of the organ's inability to regenerate amidst massive cell death, and few therapeutic options exist. The mechanisms coordinating damage protection and repair are poorly understood. Here, we show that S-nitrosothiols regulate liver growth during development and after injury in vivo; in zebrafish, nitric-oxide (NO) enhanced liver formation independently of cGMP-mediated vasoactive effects. After acetaminophen (APAP) exposure, inhibition of the enzymatic regulator S-nitrosoglutathione reductase (GSNOR) minimized toxic liver damage, increased cell proliferation, and improved survival through sustained activation of the cytoprotective Nrf2 pathway. Preclinical studies of APAP injury in GSNOR-deficient mice confirmed conservation of hepatoprotective properties of S-nitrosothiol signaling across vertebrates; a GSNOR-specific inhibitor improved liver histology and acted with the approved therapy N-acetylcysteine to expand the therapeutic time window and improve outcome. These studies demonstrate that GSNOR inhibitors will be beneficial therapeutic candidates for treating liver injury.

Rargb regulates organ laterality in a zebrafish model of right atrial isomerism

Developmental signals determine organ morphology and position during embryogenesis. To discover novel modifiers of liver development, we performed a chemical genetic screen in zebrafish and identified retinoic acid as a positive regulator of hepatogenesis. Knockdown of the four RA receptors revealed that all receptors affect liver formation, however specific receptors exert differential effects. Rargb knockdown results in bilateral livers but does not impact organ size, revealing a unique role for Rargb in conferring left-right positional information. Bilateral populations of hepatoblasts are detectable in rargb morphants, indicating Rargb acts during hepatic specification to position the liver, and primitive endoderm is competent to form liver on both sides. Hearts remain at the midline and gut looping is perturbed in rargb morphants, suggesting Rargb affects lateral plate mesoderm migration. Overexpression of Bmp during somitogenesis similarly results in bilateral livers and midline hearts, and inhibition of Bmp signaling rescues the rargb morphant phenotype, indicating Rargb functions upstream of Bmp to regulate organ sidedness. Loss of rargb causes biliary and organ laterality defects as well as asplenia, paralleling symptoms of the human condition right atrial isomerism. Our findings uncover a novel role for RA in regulating organ laterality and provide an animal model of one form of human heterotaxia.

A randomized trial comparing uncovered and partially covered self-expandable metal stents in the palliation of distal malignant biliary obstruction

BACKGROUND

The most common complication of uncovered biliary self-expandable metal stents (SEMSs) is tumor ingrowth. The addition of an impenetrable covering may prolong stent patency.

OBJECTIVE

To compare stent patency between uncovered and partially covered SEMSs in malignant biliary obstruction.

DESIGN

Multicenter randomized trial.

SETTING

Four teaching hospitals.

PATIENTS

Adults with inoperable distal malignant biliary obstruction.

INTERVENTIONS

Uncovered or partially covered SEMS insertion.

MAIN OUTCOME MEASURES

Time to recurrent biliary obstruction, patient survival, serious adverse events, and mechanism of recurrent biliary obstruction.

RESULTS

From October 2002 to May 2008, 129 patients were randomized. Recurrent biliary obstruction was observed in 11 of 61 uncovered SEMSs (18%) and 20 of 68 partially covered SEMSs (29%). The median times to recurrent biliary obstruction were 711 days and 357 days for the uncovered and partially covered SEMS groups, respectively (P = .530). Median patient survival was 239 days for the uncovered SEMS and 227 days for the partially covered SEMS groups (P = .997). Serious adverse events occurred in 27 (44%) and 42 (62%) patients in the uncovered and partially covered SEMS groups, respectively (P = .046). None of the uncovered and 8 (12%) of the partially covered SEMSs migrated (P = .0061).

LIMITATIONS

Intended sample size was not reached. Allocation to treatment groups was unequal.

CONCLUSIONS

There was no significant difference in time to recurrent biliary obstruction or patient survival between the partially covered and uncovered SEMS groups. Partially covered SEMSs were associated with more serious adverse events, particularly migration.

Lower gastrointestinal bleeding

Lower gastrointestinal (GI) hemorrhage is a significant cause of morbidity and mortality, particularly in elderly patients. Lower endoscopic evaluation is established as the diagnostic procedure of choice in the setting of acute lower GI hemorrhage.

Single-operator duodenoscope-assisted cholangioscopy is an effective alternative in the management of choledocholithiasis not removed by conventional methods, including mechanical lithotripsy

BACKGROUND AND STUDY AIMS

The widespread use of cholangioscopy in the management of difficult choledocholithiasis has been limited by the need for two expert operators. This report describes the use of a technique of single-operator duodenoscope-assisted cholangioscopy (SODAC) in the successful management of 75 patients with choledocholithiasis.

PATIENTS AND METHODS

The single-operator technique, allowing simultaneous control of both the duodenoscope and cholangioscope, was prospectively studied between June 1999 and June 2001 in the diagnosis and treatment of choledocholithiasis.

RESULTS

A total of 109 SODAC procedures were conducted in 75 patients to manage choledocholithiasis. The indications were: firstly, SODAC-guided electrohydraulic lithotripsy (EHL) of stones in which conventional methods, including mechanical lithotripsy, had not been successful (52 SODAC procedures in 26 patients); and secondly, direct visualization of the biliary tree after cholangiography to assess the presence of stones (57 SODAC procedures in 49 patients). The locations and numbers of the stones, but not their size, were predictive of the number of SODAC-guided lithotripsy sessions required. All of the patients were free of stones at the end of the study period, and no complications were recorded.

CONCLUSIONS

Single-operator SODAC-guided electrohydraulic lithotripsy was effective in the treatment of difficult cases of choledocholithiasis in which conventional methods had previously failed. The technique may allow increased use of cholangioscopy in the management of choledocholithiasis.

Treatment of bleeding colonic diverticula by endoscopic band ligation: an in-vivo and ex-vivo pilot study

BACKGROUND AND STUDY AIMS

Angiographic and surgical therapy are standards of care for persistent diverticular bleeding. Colonoscopic intervention using epinephrine injection, multipolar electrocautery, and placement of an Endoclip has not gained widespread acceptance due to concerns about complications,and the widespread management of severe lower gastrointestinal bleeding by surgeons and interventional radiologists. The utility of colonoscopic band ligation for control of diverticular bleeding was evaluated both in vivo and ex vivo.

PATIENTS AND METHODS

Endoscopic band ligation of diverticula was performed on surgical resection specimens and in patients with actively bleeding colonic diverticula.

RESULTS

In the in-vivo study, active diverticular bleeding was completely controlled in four patients by endoscopic band ligation. In two cases, a visible vessel was seen on the everted and banded diverticulum. Procedure time ranged from 45 to 140 min. The total lengths of hospital stays for the four patients were 2, 6, 14, and 35 days. The long hospital stays (> 7 days)were associated with non-gastrointestinal co-morbidity. There were no acute complications of band ligation. No rebleeding or need for surgery occurred during a follow-up period of 12 months in any of the patients. In the ex-vivo study, 11 diverticula were successfully everted and banded in five of nine surgical specimens (one right colon and four left colons). Mucosa was identified in all of the "banded" segments. Ten of 11 ligated diverticula revealed evidence of blood vessels or submucosal tissue. The presence of subserosal fat was suggested in three of the 11 "banded" segments, and none of the ex-vivo ligated diverticula contained muscularis propria or serosal involvement. There was no evidence of perforation.

CONCLUSIONS

Both in-vivo and ex-vivo data suggest that endoscopic band ligation may be a safe and effective therapy for actively bleeding colonic diverticula.

Duodenoscope assisted cholangiopancreatoscopy: a review of clinical applications

Duodenoscope assisted cholangiopancreatoscopy allows direct visualization of the pancreatic duct and bile duct. There are several circumstances where direct ductal visualization might be helpful in clarifying a diagnosis or providing targeted treatment. Duodenoscope assisted cholangiopancreatoscopy is currently employed for a variety of indications including: indeterminate ductal strictures and filling defects, marginal chronic pancreatitis, treatment of large intraductal stones, localization of intraductal papillary mucinous tumors, and localization and treatment of hemobilia. There have however been no randomized controlled trials evaluating the diagnostic or therapeutic functions of duodenoscope assisted cholangiopancreatoscopy. This article reviews recent descriptive studies that attempt to clarify the clinical role of this technology.

Pancreatic stent placement for duct disruption

BACKGROUND

The aim of this study was to identify predictors of outcome after pancreatic duct stent placement for duct disruption.

METHODS

Patients were identified from endoscopy databases. Disruption was defined by extravasation of contrast from the pancreatic duct during endoscopic retrograde pancreatography. Data collected included demographic information, imaging studies, management before and outcome after stent placement. Success was defined as resolution of the disruption clinically, on radiologic imaging, and/or at endoscopic retrograde pancreatography.

RESULTS

Forty-three patients (23 women, 20 men; mean age 57 years, [SD] 15.2 years) were studied. The etiology of pancreatic duct disruption was acute pancreatitis in 24, chronic pancreatitis in 9, operative injury in 7, and trauma in 3 patients. In 25 patients there was resolution of the disruption, whereas stent therapy was unsuccessful in 16 and the outcome was indeterminate in 2 patients. On univariate analysis, stent positioned to bridge the disruption (p = 0.04) and longer duration of stent therapy (p = 0.002) were associated with a successful outcome. Female gender (p = 0.05) and acute pancreatitis (p = 0.05) were associated with a lack of success. On multivariate analysis, only the bridging stent position remained correlated to outcome. Complications occurred in 4 patients.

CONCLUSIONS

A bridging stent is associated with a successful outcome after pancreatic duct stent placement for duct disruption.

Optical coherence tomography of the biliary tree during ERCP

BACKGROUND

Optical coherence tomography (OCT) is a high-resolution imaging technique that produces cross-sectional images in vivo. This is a report of the first use of OCT to acquire images of the biliary tree during ERCP.

METHODS

A 2.6-mm diameter OCT catheter delivered through the accessory channel of a duodenoscope was used to acquire images of the intrahepatic and extrahepatic bile ducts in 5 patients. Histology-correlated OCT images of 5 cadaveric livers, each imaged at 3 sites, were used to guide interpretation of the in vivo images.

RESULTS

Biliary ductal epithelium and subepithelial structures, including peribiliary glands, vasculature, and hepatic parenchyma, were visualized in vivo. The papillary architecture of cholangiocarcinoma was identified by OCT. There were no OCT-related complications.

CONCLUSIONS

High-resolution OCT imaging of the biliary tree is feasible and may provide useful diagnostic information during ERCP.

The use of EUS to diagnose malignant portal venous system invasion by pancreatic cancer

BACKGROUND

CT scanning and mesenteric angiography are insensitive tests diagnosing vascular invasion by pancreatic cancer. Endoscopic ultrasound (EUS) has been proposed as an alternative. The sensitivity, specificity, and accuracy of specific EUS criteria for diagnosing malignant invasion of the branches of the portal venous system have not been determined.

METHODS

This is a prospective blinded evaluation of EUS and angiography to diagnose malignant invasion of the portal venous system by pancreatic cancer in 45 patients, 28 of whom underwent surgery. Surgical staging was used as the gold standard for determining the accuracy of EUS and angiography.

RESULTS

Four EUS criteria were studied and the overall accuracy rates were as follows: irregular venous wall (87%), loss of interface (78%), proximity of mass (73%), and size (39%). Although "irregular venous wall" was the most accurate, it suffered from a low sensitivity rate (47%) because of its relative inability to detect superior mesenteric vein invasion (sensitivity of 17%). The angiographic criteria had accuracy rates of 73% to 90% with low sensitivity rates (20% to 77%). The clean resection rate was 86% when all tests were used, 78% if EUS was used without angiography, and 60% if only angiography was used.

CONCLUSION

EUS is highly sensitive for detecting portal and splenic vein invasion by pancreatic cancer, but may be insensitive for superior mesenteric vein involvement.

Embolization of an hepatic artery pseudoaneurysm following laparoscopic cholecystectomy

Vascular injuries during laparoscopic cholecystectomy can occur in an analogous fashion to biliary injuries, with potential laceration, transection, and occlusion of blood vessels. A patient presented with symptomatic hemobilia 1 month following laparoscopic cholecystectomy and was found to have a right hepatic artery pseudoaneurysm which communicated with the common bile duct. This was successfully embolized with several embolic agents, resulting in rapid resolution of all signs and symptoms. The patient has been free of symptoms during a follow-up period of 1 year. A brief discussion of hepatic artery pseudoaneurysms is presented.

Placement of a feeding button ("one-step button") as the initial procedure

The procedure of choice for enteral feeding access is now percutaneous endoscopic gastrostomy (PEG). Standard PEG tubes have the disadvantages of clogging, stomal enlargement, and external bulkiness. Button replacement tubes can covert the more cumbersome PEG tubes to low external profile devices. A procedure and an early experience is described for placement of a button as a single-step procedure. This procedure is an over-the-wire, "push" procedure. Sixty-nine buttons were placed, 47 (61%) for neurologic reasons and 22 (32%) for cancer and other reasons. In 49 of the 69 (71%), there was no difficulty at all with insertion, and in only two (3%) could the button not be placed. Complications were assessed at 48 h and at 3 wk. No complications were found in 61 (90%). In only two patients (3%) were there serious complications (gastro-colon-cutaneous fistula and "peritonitis"). The One-Step Button represents a rapid, safe procedure for the placement of a low-profile PEG with its attendant advantages.

Endoscopic laser lithotripsy of large bile duct stones

Experimental work has established that the Candela (Candela Laser Corporation, Wayland, MA) flashlamp excited dye laser (wavelength, 504 nm) is a highly effective method for fragmenting biliary stones and has minimal potential for injuring the bile duct wall. This technique was evaluated in 25 complex patients whose stones, usually because of large size, did not respond to standard nonoperative treatment. The laser imaging was applied through a quartz fiber and aimed either under direct vision with choledochoscopes passed percutaneously or through a special "mother" duodenoscope or under fluoroscopic guidance at standard duodenoscopy. Laser treatment resulted in some fragmentation of stones in 23 cases. Subsequently, it proved that it was possible to clear the bile duct of stones in 20 patients, 12 of them receiving successful treatment during the same endoscopic procedure. There were no significant complications. This endoscopic technique seems to be a useful new alternative to surgery in patients with large and difficult bile duct stones.

Association of Helicobacter pylori infection with dyspeptic symptoms in patients undergoing gastroduodenoscopy

PURPOSE

To determine the prevalence of Helicobacter pylori in patients with non-ulcer dyspepsia and ulcer disease as well as in a control population undergoing endoscopic retrograde cholangiopancreatography (ERCP) for suspected pancreatic or biliary disease.

PATIENTS AND METHODS

Forty-six eligible patients undergoing upper endoscopy at Massachusetts General Hospital were studied over a period of 18 months, as well as 24 patients undergoing ERCP for presumed pancreatic or biliary disease. Two biopsy specimens from the fundus and two from the antrum were taken for microbiologic and histopathologic analysis. Sera were examined by enzyme-linked immunoabsorbent assay. All specimens were processed in a blind fashion. Chi-square test with Yates' correction was used for statistical analysis.

RESULTS

H. pylori was found in 31 of 46 (67%) study patients and in six of 24 (25%) control patients (by microbiologic or histologic techniques) (p less than 0.01). H. pylori was found in all patients with peptic ulcer disease and in 60% of patients without ulcers. No association between H. pylori and any specific gastrointestinal symptom was observed. H. pylori was identified in the fundus as often as in the antrum, although in the antrum the organism was more often associated with histologic gastritis. Compared with histology, serologic assays for IgG and IgA antibodies to H. pylori had sensitivities of 100% and 94%, and specificities of 86% and 76%, respectively. Reexamination of selected specimens without knowledge of their identity revealed that the specificity of serology exceeded 94% while the sensitivity of histologic and microbiologic studies may have been closer to 80%.

CONCLUSIONS

H. pylori was more common in dyspeptic patients than in our control subjects undergoing ERCP. Multiple biopsy sites from fundus and antrum are required to exclude infection. Serologies of IgG and IgA were sensitive and specific for H. pylori, suggesting a possible role for non-endoscopic diagnosis of this infection. The frequent association of H. pylori with active inflammation rather than with quiescent gastritis is consistent with a pathologic role of this organism.

Endoscopic palliation of obstructive esophagogastric malignancy

To investigate the efficacy of alternative endoscopic palliative therapies for obstructive esophagogastric malignancy, the experience of 53 patients treated between 1979 and 1986 was analyzed. Forty-seven patients had placement of intraesophageal prostheses. Ten patients had prostheses placed after neodymium:YAG laser therapy. In four of these patients, prosthesis placement was planned as part of the initial therapy. Twelve patients initially received laser therapy. In six, recurrent tumor was treated with intraesophageal prostheses 3 to 24 weeks after laser treatment. Comparing neodymium:YAG laser therapy to placement of the prosthesis, both techniques provided similar improvement in dysphagia. Patients receiving prostheses required less additional treatment for dysphagia. Life table analysis comparing survival rates from diagnosis to death showed no difference. The palliation provided by prostheses and neodymium:YAG laser appears to be quite similar; however, the prosthesis seems to be more lasting and require fewer resources.

Laser lithotripsy: animal studies of safety and efficacy

The safety and efficacy of pulsed tunable dye laser fragmentation of common bile duct stones was assessed in pigs. Laser pulses were conducted through a flexible quartz fiber that was in direct contact with stones that had been surgically implanted into the common bile duct. All calculi were rapidly fragmented into small pieces without significant damage to the common bile duct. The immediate and delayed effects of pulsed lasers on the common bile duct were also evaluated. The common bile duct demonstrated a high tolerance to laser-induced damage even when the laser was discharged directly into the bile duct wall. These results suggest that laser lithotripsy can be performed in humans with a high degree of safety and efficacy.

Recanalization of occluded biliary endoprostheses with pulsed laser radiation

The use of pulsed laser radiation to recanalize occluded biliary endoprostheses was examined. In vitro measurements demonstrated that a repetitively pulsed organic dye laser transmitted through a small diameter quartz fiber can recanalize an occluded stent in less than 10 sec without causing visible damage to the stent. The laser parameters required for recanalization do not result in significant damage to the common bile duct of a pig even when the laser energy is delivered directly into the tissue, indicating that biliary endoprostheses can be cleared with a large margin of safety. Although the duration of this effect is unknown, pulsed laser radiation is a simple, safe, and effective means of recanalizing occluded biliary endoprostheses and may be an alternative to stent replacement.

Successful treatment of nonhealing biliary-cutaneous fistulas with biliary stents

Biliary-cutaneous fistulas occasionally complicate biliary tract surgery. Distal biliary obstruction, extensive loss of bile duct wall, or infection may contribute to the failure of such fistulas to heal. Five cases are reported of high-volume persistent fistulas that healed promptly after placement of endoscopic (4 cases) or percutaneous (1 case) biliary stents. Biliary stent placement eliminated the need for difficult reoperations in these complex patients and offers a promising therapeutic approach to this problem.

Sulfasalazine-induced agranulocytosis

We report a patient with ulcerative colitis in whom agranulocytosis was diagnosed 5 wk after the initiation of sulfasalazine therapy. Concomitant features included fever and skin rash, and bone marrow examination revealed severe myeloid hypoplasia. Antineutrophil antibodies were absent from the serum. Recovery began during the 2nd wk and was characterized by a leukemoid reaction with thrombocytosis. Subsequently, the patient received 5-aminosalicylate enemas without adverse effects. Agranulocytosis, a rare effect of sulfasalazine, appears to occur almost invariably during the first 2 months of therapy, and prompt evaluation is therefore required in patients with unexplained fever or other nonspecific illness during this period.