Rapid Polyolefin Hydrogenolysis by a Single-Site Organo-Tantalum Catalyst on a Super-Acidic Support: Structure and Mechanism.

The novel electrophilic organo-tantalum catalyst AlS/TaNpx (1) (Np=neopentyl) is prepared by chemisorption of the alkylidene Np3 Ta=CHt Bu onto highly Brønsted acidic sulfated alumina (AlS). The proposed catalyst structure is supported by EXAFS, XANES, ICP, DRIFTS, elemental analysis, and SSNMR measurements and is in good agreement with DFT analysis. Catalyst 1 is highly effective for the hydrogenolysis of diverse linear and branched hydrocarbons, ranging from C2 to polyolefins. To the best of our knowledge, 1 exhibits one of the highest polyolefin hydrogenolysis activities (9,800 (CH2 units) ⋅ mol(Ta)-1 ⋅ h-1 at 200 °C/17 atm H2 ) reported to date in the peer-reviewed literature. Unlike the AlS/ZrNp2 analog, the Ta catalyst is more thermally stable and offers multiple potential C-C bond activation pathways. For hydrogenolysis, AlS/TaNpx is effective for a wide variety of pre- and post-consumer polyolefin plastics and is not significantly deactivated by standard polyolefin additives at typical industrial concentrations.

Single-Site Carbon-Supported Metal-Oxo Complexes in Heterogeneous Catalysis: Structure, Reactivity, and Mechanism.

When early transition metal complexes are molecularly grafted onto catalyst supports, well-defined, surface-bound species are created, which are highly active and selective single-site heterogeneous catalysts (SSHCs) for diverse chemical transformations. In this minireview, we analyze and summarize a less conventional type of SSHC in which molybdenum dioxo species are grafted onto unusual carbon-unsaturated scaffolds, such as activated carbon, reduced graphene oxide, and carbon nanohorns. The choice of earth-abundant, low-toxicity, versatile metal constituents, and various carbon supports illustrates "catalyst by design" principles and yields insights into new catalytic systems of both academic and technological interest. Here, we summarize experimental and computational investigations of the bonding, electronic structure, reaction scope, and mechanistic pathways of these unusual catalysts.

Accuracy and Inter-observer Agreement Among Endoscopists for Visual Identification of Colorectal Polyps Using Endoscopy Images.

BACKGROUND: It is essential to accurately distinguish small benign hyperplastic colon polyps (HP) from sessile serrated lesions (SSL) or adenomatous polyps (TA) based on endoscopic appearances. Our objective was to determine the accuracy and inter-observer agreements for the endoscopic diagnosis of small polyps. METHODS: High-quality endoscopic images of 30 small HPs, SSLs, and TAs were used randomly to create two-timed PowerPoint slide sets-one with and another one without information on polyp size and location. Seven endoscopists viewed the slides on two separate occasions 90 days apart, identified the polyp type, and graded their confidence level. Overall and polyp-specific accuracies were assessed for the group and individual endoscopists. Chi-square tests and Kappa (κ) statistics were used to compare differences as appropriate. RESULTS: When polyp size and location were provided, overall accuracy was 67.1% for TAs, 50.0% for SSLs, and 41.4% for HPs; the corresponding accuracies were 60%, 44.3%, and 34.3% when polyp size and location were withheld (p < .001). Inter-observer agreement was moderate for TAs (κ = 0.50) and fair for SSLs (κ = 0.26) and HPs (κ = 0.29); the corresponding inter-observer agreements were 0.44, 0.31, and 0.17 with polyp size and location withheld. Accuracy was not affected by knowledge of polyp size, location, or confidence level. Endoscopists with ≥ 10 years (vs. < 10 years) of colonoscopy experience had marginally higher (56% vs. 40%, p = 0.05) accuracy for SSL diagnosis. CONCLUSIONS: The ability to distinguish between small TAs, SSLs, and HPs on their endoscopic appearance is poor regardless of the endoscopists' knowledge of polyp size and location.

Off-Label Use of Multitarget Stool DNA Testing in Primary Care.

INTRODUCTION: We evaluated the off-label use of multitarget stool DNA (mt-sDNA) testing in the primary care setting. METHODS: We reviewed all mt-sDNA orders between July 1, 2018, and June 30, 2019, to determine the frequency of off-label mt-sDNA orders. RESULTS: Nine hundred two patients with mt-sDNA orders were evaluated, of which 160/902 patients (17.7%) met at least 1 criterion for off-label mt-sDNA order. Increasing age was associated with off-label order (Odds Ratio [OR] 2.32 [95% CI, 1.86-2.89] for every 10-year increase in age, P < 0.0001). On multivariate analysis, increased age (OR 1.04 [1.02-1.06], P = 0.001) and need for diagnostic colonoscopy (OR 2.9 [1.01-8.34], P = 0.048) were associated with a positive mt-sDNA result. DISCUSSION: Off-label mt-sDNA testing is common, and further efforts are needed to educate patients and providers on appropriate use of mt-sDNA for colorectal cancer screening.

Superiority of Higher-Volume Fresh Feces Compared to Lower-Volume Frozen Feces in Fecal Microbiota Transplantation for Recurrent Clostridioides Difficile Colitis.

GOALS: To compare the clinical outcomes of different protocols for fecal microbiota transplantation (FMT) in two community hospitals with similar patient demographics. BACKGROUND: FMT is commonly performed for recurrent or refractory Clostridioides difficile infection (rCDI). The clinical efficacy of FMT for this indication has been well established. However, there has been no standardization or optimization of the amount of fecal material, method of feces preparation, or route of delivery for FMT. STUDY: In this retrospective study, patients with rCDI received FMT using commercially available frozen fecal preparation (22.7 g) at Center A and locally prepared fresh fecal filtrate (30-50 g) at Center B. The primary outcome was defined as complete resolution of clinical symptoms related to rCDI after at least 8 weeks of follow-up. RESULTS: Fifty patients from each center were included in the study. Clinical success after initial FMT with lower-volume frozen fecal preparation at Center A was 32/50 (64.0%) compared to 49/50 (98.0%) with higher-volume fresh fecal filtrate at Center B (p < 0.0001). Seventeen patients in Center A and 1 patient in Center B underwent at least one repeat FMT. Overall clinical success was achieved in 43/50 (86%) of patients in Center A and 50/50 (100%) in Center B (p = 0.012). CONCLUSIONS: Our results suggest superior clinical efficacy of a larger amount of fresh fecal filtrate over a smaller amount of commercially available frozen fecal preparation. Further studies are needed to examine the effect of varying amounts of feces and the optimal protocol for FMT in patients with rCDI.

Gastrointestinal and Liver Manifestations of COVID-19.

The worldwide pandemic of COVID-19, caused by the virus SARS-CoV,-2 has continued to progress, and increasing information is becoming available about the incidence of digestive symptoms as well as abnormal liver-associated enzymes in patients who are infected. These are postulated to be related to the virus's use of ACE-2 receptors located on certain intestinal cells, cholangiocytes, and hepatocytes. This brief review summarizes the available limited data on digestive manifestations of COVID-19. A significant proportion of COVID-19 patients can present initially with only digestive complaints. The most common digestive symptoms are anorexia, nausea, vomiting, and diarrhea. Liver-related transaminases are elevated in a substantial proportion of patients, although generally only mildly elevated. Currently there is no firm evidence to suggest that severity of digestive symptoms corresponds to severity of COVID-19 clinical course, however, more severe alterations in liver enzymes may correlate with worse clinical course. Given use of antiviral and antibacterial agents in sicker patients, drug-induced liver injury cannot be ruled out either in these cases. Although viral RNA can be detected in stool, it is unclear whether fecal-oral transmission can be achieved by the virus. As further data becomes available, our understanding of the digestive manifestations of COVID-19 will continue to evolve.

Successful Hemostasis With Endoscopic Suturing of Recurrent Duodenal Ulcer Bleeding After Failed Initial Endoscopic Therapy and Embolization.

Peptic ulcer bleeding is a common condition where endoscopic therapy offers a safe and definitive treatment. However, management of peptic ulcer bleeding can be more complex when there is large volume, recurrent bleeding in a critically ill patient. We present a patient with life-threatening, recurrent duodenal ulcer bleeding who failed both standard endoscopic therapy and transarterial embolization. Hemostasis was achieved through a combination of standard endoscopic therapy and endoscopic suturing.

Endoscopic full-thickness resection using a clip non-exposed method for gastrointestinal tract lesions: a meta-analysis.

Background and study aims Endoscopic full-thickness resection (EFTR) allows for treatment of epithelial and sub-epithelial lesions (SELs) unsuitable to conventional resection techniques. This meta-analysis aimed to assess the efficacy and safety of clip-assisted method for non-exposed EFTR using FTRD or over-the-scope clip of gastrointestinal tumors. Methods A comprehensive literature search was performed. The primary outcome of interest was the rate of histologic complete resection (R0). Secondary outcomes of interest were the rate of enbloc resection, FTR, adverse events, and post-EFTR surgery. Random-effects model was used to calculate pooled estimates and generate forest plots. Results Eighteen studies with 730 patients and 733 lesions were included in the analyses. Indications for EFTR were difficult/residual colorectal adenoma, adenoma at a diverticulum or appendiceal orifice and early cancer (n = 634), colorectal SELs (n = 42), and upper gastrointestinal lesions (n = 51), other colonic lesions (n = 6). Median size of lesions was 13.5 mm. There were 22 failed EFTR attempts. Pooled overall R0 resection rate was 82 % (95 % CI: 75, 89). The pooled overall FTR rate was 83 % (95 % CI: 77, 89). The pooled overall enbloc resection rate was 95 (95 % CI: 92, 96). The pooled estimates for perforation and bleeding were < 0.1 % and 2 %, respectively. Following EFTR, a total of 110 patients underwent surgery for any reason [pooled rate 7 % (95 % 2, 14). The pooled rates for post-EFTR surgery due to invasive cancer, for non-curative endoscopic resection and for adverse events were 4 %, < 0.1 % and < 0.1 %, respectively. No mortality related to EFTR was noted. Conclusions EFTR appears to be safe and effective for gastrointestinal lesions that are not amenable to conventional endoscopic resection. This technique should be considered as an alternative to surgery in selected cases.

Endoscopic suturing for management of peptic ulcer-related upper gastrointestinal bleeding: a preliminary experience.

Background and study aims Acute non-variceal upper gastrointestinal bleeding (UGIB) due to peptic ulcer disease (PUD) remains a common and challenging emergency managed by gastroenterologists. The proper role of endoscopic suturing on the management of PUD-related UGIB is unknown. Patients and methods This is an international case series of patients who underwent endoscopic suturing for bleeding PUD. Primary outcome was rate of immediate hemostasis and rate of early rebleeding (within 72 hours). Secondary outcomes included technical success, delayed rebleeding (> 72 hours), and rate of adverse events (AEs). Results Ten patients (mean age 66.7 years, 30 % female) were included in this study. Nine (90 %) had prior failed endoscopy hemostasis with an average of 1.4 ±â€Š0.7 (range 1 - 3) prior endoscopic sessions. Forrest classification was Ib in 5 (50 %), IIa in 3 (30 %), IIb in 1(10 %), and IIc in 1 (10 %). Mean suturing time was 13.4 ±â€Š5.6 (range 3.5 to 20) minutes. Technical success was 100 %. Rate of immediate hemostasis was 100 % and rate of early rebleeding was 0 %. Mean number of sutures was 1.5 (range, 1 - 4). No AEs were observed. Delayed recurrent bleeding was not observed in any cases after a median of 11 months (range 2 - 56), after endoscopic suturing. Conclusions Oversewing of a bleeding or high-risk ulcer using endoscopic suturing appears to be a safe and effective method for achieving endoscopic hemostasis. It may be considered as rescue endoscopic therapy when primary endoscopic hemostasis fails to control the bleeding or when hemorrhage recurs after successful control of bleeding.

Erratum: EUS-guided gastroenterostomy in management of benign gastric outlet obstruction.

[This corrects the article DOI: 10.1055/s-0043-123468.].

Peroral endoscopic myotomy is effective and safe in non-achalasia esophageal motility disorders: an international multicenter study.

BACKGROUND AND STUDY AIMS: The efficacy of per oral endoscopic myotomy (POEM) in non-achalasia esophageal motility disorders such as esophagogastric junction outflow obstruction (EGJOO), diffuse esophageal spasm (DES), and jackhammer esophagus (JE) has not been well demonstrated. The aim of this international multicenter study was to assess clinical outcomes of POEM in patients with non-achalasia disorders, namely DES, JE, and EGJOO, in a large cohort of patients. PATIENTS AND METHODS: This was a retrospective study at 11 centers. Consecutive patients who underwent POEM for EGJOO, DES, or JE between 1/2014 and 9/2016 were included. Rates of technical success (completion of myotomy), clinical response (symptom improvement/Eckardt score ≤ 3), and adverse events (AEs, severity per ASGE lexicon) were ascertained . RESULTS: Fifty patients (56 % female; mean age 61.7 years) underwent POEM for EGJOO (n = 15), DES (n = 17), and JE (n = 18). The majority of patients (68 %) were treatment-naïve. Technical success was achieved in all patients with a mean procedural time of 88.4 ±â€Š44.7 min. Mean total myotomy length was 15.1 ±â€Š4.7 cm. Chest pain improved in 88.9 % of EGJOO and 87.0 % of DES/JE ( P  = 0.88). Clinical success was achieved in 93.3 % of EGJOO and in 84.9 % of DES/JE ( P  = 0.41) with a median follow-up of 195 and 272 days, respectively. Mean Eckardt score decreased from 6.2 to 1.0 in EGJOO ( P  < 0.001) and from 6.9 to 1.9 in DES/JE ( P  < 0.001). A total of 9 (18 %) AEs occurred and were rated as mild in 55.6 % and moderate in 44.4 %. CONCLUSION: POEM is effective and safe in management of non-achalasia esophageal motility disorders, which include DES, JE, and EGJOO.

Incidence and risk factors of advanced neoplasia after endoscopic mucosal resection of colonic laterally spreading lesions.

PURPOSE: To investigate advanced neoplasia (AN) after endoscopic mucosal resection (EMR) of colonic laterally spreading lesions (LSLs). METHODS: A retrospective study of patients who underwent injection-assisted EMR of colonic LSLs ≥ 10 mm was performed. Primary outcome was overall rate of AN at initial surveillance colonoscopy. Secondary outcomes were the rates of residual AN (rAN) at the EMR site and metachronous AN (mAN), and analysis of risk factors for AN, including effect of surveillance guidance. RESULTS: Three hundred seventy-four patients underwent successful EMR for 388 LSLs. AN occurred in 66/374 (17.6%) patients on initial surveillance colonoscopy at median follow-up of 364.5 days. Two patients had both rAN and mAN, for a total of 68 instances of AN, including 30/374 (8.0%) cases of rAN and 38/374 (10.2%) cases of mAN. On multivariate analysis, use of piecemeal resection was associated with increased likelihood of residual AN (P = 0.003, OR 9.2, 95% CI 2.1-33.3). Twenty-nine out of thirty cases (96.7%) of rAN were successfully endoscopically managed at surveillance colonoscopy. CONCLUSIONS: AN occurred in 17.6% of all patients at initial surveillance colonoscopy at a median of 1 year after EMR. Roughly half of the instances of AN were metachronous lesions. Our data support a 1-year surveillance interval after EMR of LSLs ≥ 10 mm with careful inspection of the entire colon, not just the prior resection site.

EUS-guided gastroenterostomy in management of benign gastric outlet obstruction.

Background and study aims: Endoscopic ultrasound-guided gastroenterostomy (EUS-GE) in malignant gastric outlet obstruction (GOO) appears to be promising; however, its role in benign GOO is unclear. The aim of this study was to ascertain the clinical efficacy and safety of EUS-GE in benign GOO. Patients and methods: This was an international retrospective series involving 5 tertiary centers. Consecutive patients who underwent EUS-GE between 1/2013 - 10/2016 for benign GOO were included. The primary endpoint was the rate of clinical success defined as ability to tolerate oral intake without vomiting. Secondary endpoints included technical success and rate of adverse events (AE). Results: Overall, 26 patients (46.2 % female; mean age 57.7 ±â€Š13.9 years) underwent EUS-GE for benign GOO due to strictures from chronic pancreatitis (n = 11), surgical anastomosis (n = 6), peptic ulcer disease (n = 5), acute pancreatitis (n = 1), superior mesentery artery syndrome (n = 1), caustic injury (n = 1), and hematoma (n = 1). Technical success was achieved in 96.2 %. Dilation of the lumen apposing metal stent was performed in 13/25 (52 %) with a mean maximum diameter of 14.6 ±â€Š1.0 mm. Mean procedure time was 44.6 ±â€Š26.1 min. Clinical success was observed in 84.0 % with a mean time to oral intake of 1.4 ±â€Š1.9 days and a median follow-up of 176.5 (IQR: 47 - 445.75) days. Rate of unplanned re-intervention was 4.8 %. 3 AE were noted including 2 misdeployed stents and 1 gastric leak needing surgical intervention following elective GE stent removal. Conclusions: EUS-GE is a promising treatment for benign GOO. Larger and prospective data are needed to further validate this novel endoscopic technique in treating benign GOO of various etiologies.

Fully-covered metal stents with endoscopic suturing vs. partially-covered metal stents for benign upper gastrointestinal diseases: a comparative study.

BACKGROUND AND STUDY AIMS: Self-expandable metallic stents (SEMS) have been increasingly used in benign conditions (e. g. strictures, fistulas, leaks, and perforations). Fully covered SEMS (FSEMS) were introduced to avoid undesirable consequences of partially covered SEMS (PSEMS), but come with higher risk of stent migration. Endoscopic suturing (ES) for stent fixation has been shown to reduce migration of FSEMS. Our aim was to compare the outcomes of FSEMS with ES (FS/ES) versus PSEMS in patients with benign upper gastrointestinal conditions. PATIENTS AND METHODS: We retrospectively identified all patients who underwent stent placement for benign gastrointestinal conditions at seven US tertiary-care centers. Patients were divided into two groups: FSEMS with ES (FS/ES group) and PSEMS (PSEMS group). Clinical outcomes between the two groups were compared. RESULTS: A total of 74 (FS/ES 46, PSEMS 28) patients were included. On multivariable analysis, there was no significant difference in rate of stent migration between FS/ES (43 %) and PSEMS (15 %) (adjusted odds ratio 0.56; 95 % CI 0.15 - 2.00). Clinical success was similar [68 % vs. 64 %; P  = 0.81]. Rate of adverse events (AEs) was higher in PSEMS group [13 (46 %) vs. 10 (21 %); P  = 0.03). Difficult stent removal was higher in the PSEMS group (n = 5;17 %) vs. 0 % in the FS/ES group; P  = 0.005. CONCLUSIONS: The proportion of stent migration of FS/ES and PSEMS are similar. Rates of other stent-related AEs were higher in the PSEMS group. PSEMS was associated with tissue ingrowth or overgrowth leading to difficult stent removal, and secondary stricture formation. Thus, FSEMS with ES for stent fixation may be the preferred modality over PSEMS for the treatment of benign upper gastrointestinal conditions.

En bloc endoscopic mucosal resection is equally effective for sessile serrated polyps and conventional adenomas.

BACKGROUND: Sessile serrated polyps (SSPs) are associated with higher rates of incomplete resection compared to conventional adenomas after traditional snare polypectomy. Outcomes after endoscopic mucosal resection (EMR) are less established. The aim of this study was to evaluate the rate of residual neoplasia at surveillance colonoscopy for SSPs compared to conventional adenomas ≥ 10 mm after en bloc EMR. METHODS: Retrospective cohort study of consecutive patients referred for EMR of a colonic lesion ≥ 10 mm from 2005 to 2013. Data on procedures, histopathology, and surveillance colonoscopies were recorded. The primary outcome was rate of macroscopically evident residual neoplasia at surveillance colonoscopy for SSPs compared to adenomas. Secondary outcomes included rate of neoplasia at the resection margin. RESULTS: 283 consecutive patients with 293 polyps underwent en bloc EMR including 101 SSPs and 192 adenomas. Pathology commented on the lateral resection margins of the specimen in 235 cases (80%). Of these, neoplasia was noted at the resection margin in 29/64 SSPs (45.3%) compared to 65/171 adenomas (38.0%; P = .37). Surveillance data were available for 153 index lesions with a median interval of 13 months (interquartile range, 10.75-23.25 months). Ten resection sites (6.5%) were found to have residual neoplasia, including 2/52 SSPs (3.8%) and 8/101 adenomas (7.9%; P = .50). Of the cases with surveillance data 128/153 (84%) commented on the lateral margin of the resection specimen. Residual neoplasia was noted in 3/68 lesions (4.4%) with negative margins compared to 5/60 lesions (8.3%) with positive margins (P = .47). CONCLUSIONS: En bloc EMR for colonic lesions ≥ 10 mm is associated with a 6.5% rate of macroscopic residual neoplasia. Although 45% of SSPs had neoplasia extending to the resection margin, rates of residual neoplasia at surveillance colonoscopy were low. These results suggest that when feasible en bloc EMR is a reasonable option to resect SSPs ≥ 10 mm.

EUS-guided gastroenterostomy: a multicenter study comparing the direct and balloon-assisted techniques.

BACKGROUND: EUS-guided gastroenterostomy (EUS-GE) is a developing modality in the management of gastric outlet obstruction (GOO) with several technical approaches, including the direct and balloon-assisted techniques. The aim of this study was to compare the direct with the balloon-assisted modality while further defining the role of EUS-GE in GOO. METHODS: This multicenter, retrospective study involved consecutive patients who underwent EUS-GE with the direct or balloon-assisted technique for GOO (January 2014 to October 2016). The primary outcome was technical success. Secondary outcomes were success (ability to tolerate at least a full fluid diet), procedure time, and rate/severity of adverse events (AEs). RESULTS: A total of 74 patients (44.6% women; mean age 63.0 ± 11.7 years) underwent EUS-GE for GOO (direct gastroenterostomy, n = 52; balloon-assisted gastroenterostomy, n = 22). GOO was of malignant and benign etiology in 66.2% and 33.8% of patients, respectively. Technical success was achieved in 94.2% of the direct and 90.9% of the balloon-assisted approach (P = .63). Mean procedure time was shorter with the direct technique (35.7 ± 32.1 minutes vs 89.9 ± 33.3 minutes, P < .001). The clinical success rate was 92.3% for the direct technique and 90.9% for the balloon-assisted modality (P = 1.00), with a mean time to oral intake of 1.32 ± 2.76 days. The AE rate was 6.8% with only 1 severe AE noted. Rate of AEs, postprocedure length of stay, need for reintervention, and survival were similar between the 2 groups. CONCLUSIONS: EUS-GE is effective and safe in the management of GOO. The direct technique may be the preferred method given its shorter procedure time when compared with the balloon-assisted approach. Prospective trials are needed to confirm these findings.

Endoscopic Therapy is Effective for Recurrent Anastomotic Biliary Strictures after Orthotopic Liver Transplantation.

INTRODUCTION: Orthotopic liver transplantation anastomotic biliary strictures (OLT ABS) are managed with endoscopic biliary stent therapy but the recurrence rate is substantial. Our aims were to retrospectively determine the recurrence rates of OLT ABS after initial successful stent therapy, characterize the management of recurrences and identify associated variables. MATERIALS AND METHODS: Clinical data from 943 patients receiving non-living donor OLT at our institution from 2005-2012 were reviewed, and 123 OLT ABS patients receiving stent therapy were identified. Features of their endoscopic stent therapy and other pertinent clinical information were evaluated. RESULTS: ABS recurred in 25.5% of patients (24/94) after an initial successful course of stent therapy. Recurrences were received a second course of endoscopic stent therapy and 67% of patients (16/24) achieved long-term remediation of ABS. Six patients underwent a third course of endoscopic stent therapy with 4 patients achieving remediation. Overall remediation rate among ABS recurrences was 83.3% (20/24). A bivariate comparison demonstrated HCV infection, age, median months of maximal stenting and a lower maximum cumulative stent diameter were risk factors for ABS recurrence. Using a Cox regression model, only HCV status proved to be a risk factor for recurrence. DISCUSSION: In conclusion repeat stent therapy achieved high stricture remediation rates. Recurrence after the first or even second course of stenting should not imply failure of endoscopic therapy. A positive HCV status may be associated with higher stricture recurrence rates and this association should be further investigated.