Mechanistic Insight into Pd(II)-Catalyzed Late-Stage Nondirected C(sp2)-H Cyanation of Toluene Using the Dual Ligands MPAA and Quinoxaline: A Density Functional Theory Investigation.

Density functional theory (DFT) calculations were performed to investigate the mechanism of Pd(II)-catalyzed late-stage nondirected C(sp2)-H cyanation of toluene. We confirmed the resting state and catalytic active species of this stoichiometric reaction, and we calculated the full catalytic cycle to obtain a favorable reaction pathway. The DFT calculation results indicate that the morphology of the active species is essential for the observed concerted metalation/deprotonation step. Although C-H activation is reversible in principle, it is the regioselectivity- or product-determining step. Our calculation results show that the regioselectivity is not only influenced by the electron effects but also by the potential steric repulsion interactions between the substrates and the specific geometry of the catalyst. Interestingly, the transmetalation process involves the largest overall change in free energy; thus, transmetalation is defined as the rate-determining step and turnover-determining step.

A novel lumen-apposing metal stent for endoscopic drainage of symptomatic pancreatic fluid collections: a retrospective study.

Background and Objectives: Previous studies showed that lumen-apposing metal stent (LAMS) provides a feasible route to perform direct endoscopic necrosectomy. However, the high risk of bleeding and migration induced by the placement of LAMS attracted attention. The aim of this study was to evaluate the safety and effectiveness of a novel LAMS. Methods: In this retrospective study, we enrolled patients with symptomatic pancreatic fluid collections (PFCs) to perform EUS-guided drainage with a LAMS in our hospital. Evaluation variables included technical success rate, clinical success rate, and adverse events. Results: Thirty-two patients with a mean age of 41.38 ± 10.72 years (53.1% males) were included in our study, and the mean size of PFC was 10.06 ± 3.03 cm. Technical success rate and clinical success rate reached 96.9% and 93.8%, respectively. Stent migration occurred in 1 patient (3.1%), and no stent-induced bleeding occurred. The outcomes of using LAMS in 10 patients with pancreatic pseudocyst and 22 patients with walled-off necrosis were comparable. Compared with pancreatic pseudocyst, walled-off necrosis needed more direct endoscopic necrosectomy times to achieve resolution (P = 0.024). Conclusions: Our study showed that the novel LAMS is effective and safe for endoscopic drainage of PFCs with a relatively low rate of adverse events. Further large-scale multicenter studies are needed to confirm the present findings.

A new, simplified endoscopic scoring system for predicting clinical outcome in gastric low-grade intraepithelial neoplasia: the "e-cout system".

BACKGROUND AND OBJECTIVES: The clinical outcomes of gastric low-grade intraepithelial neoplasia (LGIN) exhibit significant diversity, and the current reliance on endoscopic biopsy for diagnosis poses limitations in devising appropriate treatment strategies for this disease. This study aims to establish a prognostic prediction scoring system (e-Cout system) for gastric LGIN, offering a theoretical foundation for solving this clinical challenge. METHODS: Retrospectively selecting 1013 cases meeting the inclusion and exclusion criteria from over 300,000 cases of upper gastrointestinal endoscopy performed at the Digestive Endoscopy Center of our hospital between 2000 and 2022, the cohort included 484 cases as development cohort and 529 cases for validation. Employing relevant statistical analysis, we used development cohort data to establish the e-Cout system for gastric LGIN, and further used validation cohort data to for internal validation. RESULTS: In the developmental stage, based on accordant regression coefficients, we assigned point values to six risk factors for poor prognosis: 4 points for microvessel (MV) distortion, 3 points for MV thickening, 2 points for ulcer, and 1 point each for lesion size > 2cm, disease duration > 1 year, and hyperemia and redness on the lesion surface. Patients were then categorized into four risk levels: low risk (0-1 point), medium risk (2-3), high risk (4-6), and very high risk (≥7). During the validation stage, significant differences in the three different outcomes of gastric LGIN were observed across all risk levels. The probability of reversal and progression showed a significant decrease and increase, respectively, with escalating of risk levels, and these differences were statistically significant (P< 0.001). CONCLUSIONS: The proposed e-Cout system holds promise in aiding clinicians to predict the probability and risk levels of different clinical outcomes in patients with gastric LGIN. This system is expected to provide an improved foundation and guidance for the selection of clinical strategies for this disease.

PRP improves the outcomes of autologous skin graft transplantation on the esophagus by promoting angiogenesis and inhibiting fibrosis and inflammation.

Background and Objectives: Autologous skin graft (ASG) transplantation is a challenging approach but a promising option for patients to prevent postoperative esophageal stricture. Nonetheless, the current strategies require improvement. We aimed to investigate the effectiveness of the injection of platelet-rich plasma (PRP) before skin graft transplantation for extensive esophageal defects after endoscopic resection. Methods: Standardized complete circular endoscopic resection (5 cm in length) was performed in 27 pigs allocated into 3 groups. The artificial ulcers were treated with a fully covered esophageal stent (control group), ASG (ASG group), and submucosal injection of PRP with ASG (PRP-ASG group). Macroscopic evaluation and histological analysis of the remolded esophagus were performed 7, 14, and 28 days after surgery. Results: The macroscopic evaluation indicated that submucosal injection of PRP before transplantation effectively promoted the survival rate of skin grafts and decreased the rate of mucosal contraction compared with those treated with ASG or stent alone. Histological analysis of submucosal tissue showed that this modified strategy significantly promoted wound healing of reconstructed tissues by enhancing angiogenesis, facilitating collagen deposition, and decreasing inflammation and fibrogenesis. Conclusions: These findings suggested that PRP might be used as a biological supplement to increase the esophageal skin graft survival rate and improve submucosal tissue remolding in a clinically relevant porcine model. With extremely low mucosal contraction, this novel combination strategy showed the potential to effectively prevent stenosis in extensive esophageal ulcers.

Computer-aided diagnosis system for optical diagnosis of colorectal polyps under white light imaging.

OBJECTIVES: This study presents a novel computer-aided diagnosis (CADx) designed for optically diagnosing colorectal polyps using white light imaging (WLI).We aimed to evaluate the effectiveness of the CADx and its auxiliary role among endoscopists with different levels of expertise. METHODS: We collected 2,324 neoplastic and 3,735 nonneoplastic polyp WLI images for model training, and 838 colorectal polyp images from 740 patients for model validation. We compared the diagnostic accuracy of the CADx with that of 15 endoscopists under WLI and narrow band imaging (NBI). The auxiliary benefits of CADx for endoscopists of different experience levels and for identifying different types of colorectal polyps was also evaluated. RESULTS: The CADx demonstrated an optical diagnostic accuracy of 84.49%, showing considerable superiority over all endoscopists, irrespective of whether WLI or NBI was used (P < 0.001). Assistance from the CADx significantly improved the diagnostic accuracy of the endoscopists from 68.84% to 77.49% (P = 0.001), with the most significant impact observed among novice endoscopists. Notably, novices using CADx-assisted WLI outperform junior and expert endoscopists without such assistance. CONCLUSIONS: The CADx demonstrated a crucial role in substantially enhancing the precision of optical diagnosis for colorectal polyps under WLI and showed the greatest auxiliary benefits for novice endoscopists.

Clinical Characteristics and Endoscopic Management of Duodenal Lipomas: 10-Year Experience from a Tertiary Center in China.

BACKGROUND/AIMS: Duodenal lipomas are rarely found in the gastrointestinal tract. Most published literature referring to the tumors is limited to case series. There remained issues about the understanding and management of duodenal lipomas to be clarified. We aimed to investigate the clinical and endoscopic features of duodenal lipomas. Additionally, outcomes of endoscopic resection for duodenal lipomas were evaluated. MATERIALS AND METHODS: A total of 29 duodenal lipomas resected endoscopically from December 2011 to October 2021 were included. Clinical characteristics, endoscopic features, and endoscopic ultrasound findings were analyzed retrospectively. The endoscopic resection was performed in 3 ways: hot snare polypectomy, endoscopic mucosa resection, and endoscopic submucosal dissection. RESULTS: Of the 29 duodenal lipomas, 21 were located at the second portion with a mean size of 25.8 mm (range, 7-60 mm). Yamada type IV was the most common macroscopic type in 14 lesions, exhibiting a tendency of forming large peduncles. Seven patients had digestive symptoms. The occurrence of symptoms is associated with the tumor size. Endoscopic ultrasound was performed on 23 duodenal lipomas, of which 20 demonstrated homogenous echogenicity and 3 presented heterogeneous with tubular anechoic region. The endoscopic resection operation was successfully conducted on 29 patients without severe adverse events. The rate of en bloc and endoscopic complete resection was 93.1% and 86.2%, respectively. Recurrence was noted in 1 patient. CONCLUSIONS: Clinical characteristics with typical endoscopic ultrasound features are helpful in duodenal lipomas diagnosis. The endoscopic resection is a safe and effective treatment for duodenal lipomas with considerable long-term outcomes.

SGK3 overexpression correlates with a poor prognosis in endoscopically resected superficial esophageal squamous cell neoplasia: A long-term study.

BACKGROUND: The expression status of serum and glucocorticoid-induced protein kinase 3 (SGK3) in superficial esophageal squamous cell neoplasia (ESCN) remains unknown. AIM: To evaluate the SGK3 overexpression rate in ESCN and its influence on the prognosis and outcomes of patients with endoscopic resection. METHODS: A total of 92 patients who had undergone endoscopic resection for ESCN with more than 8 years of follow-up were enrolled. Immunohistochemistry was used to evaluate SGK3 expression. RESULTS: SGK3 was overexpressed in 55 (59.8%) patients with ESCN. SGK3 overexpression showed a significant correlation with death (P = 0.031). Overall survival and disease-free survival rates were higher in the normal SGK3 expression group than in the SGK3 overexpression group (P = 0.013 and P = 0.004, respectively). Cox regression analysis models demonstrated that SGK3 overexpression was an independent predictor of poor prognosis in ESCN patients (hazard ratio 4.729; 95% confidence interval: 1.042-21.458). CONCLUSION: SGK3 overexpression was detected in the majority of patients with endoscopically resected ESCN and was significantly associated with shortened survival. Thus, it might be a new prognostic factor for ESCN.

Mechanism of the Fe(iii)-catalyzed synthesis of hexahydropyrimidine with α-phenylstyrene: a DFT study.

It is very important to develop multiple C-H substitution reactions of simple alkenes to obtain complex unsaturated components. The present study focuses on a theoretical investigation of the plausible mechanism in the Fe(OTf)3-catalyzed tandem amidomethylative reactions of α-phenylstyrene. Bis(tosylamido)methane is activated by Fe(OTf)3 to form tosylformaldimine and its Fe(OTf)3-adduct. The Fe(OTf)3-adduct undergoes an intermolecular aza-Prins reaction with α-phenylstyrene to form allylamide. The DFT data support the formation of the hexahydropyrimidine derivative from allylamide, and "condensation/iminium homologation/intramolecular aza-Prins" is the optimal reaction path. At the same time, a possible reaction pathway for the conversion of the hydrolysate 1,3-diamide derivative to the hexahydropyrimidine (HHP) derivative is given. This work is thus instructive for understanding Fe(iii)-based tandem catalysis for the amidomethylative multiple-substitution reactions of alkenes.

Interventional radiology followed by endoscopic drainage for pancreatic fluid collections associated with high bleeding risk: Two case reports.

BACKGROUND: Endoscopic ultrasound (EUS)-guided transluminal drainage is an advanced technique used to treat pancreatic fluid collections (PFCs). However, gastric varices and intervening vessels may be associated with a high risk of bleeding and are, therefore, listed as relative contraindications. Herein, we report two patients who underwent interventional embolization before EUS-guided drainage. CASE SUMMARY: Two 32-year-old males developed symptomatic PFCs after acute pancreatitis and came to our hospital for further treatment. One patient suffered from intermittent abdominal pain and vomiting, and computed tomography (CT) imaging showed an encapsulated cyst 7.93 cm × 6.13 cm in size. The other patient complained of a mass inside the abdomen, which gradually became enlarged. Gastric varices around the ideal puncture site were detected by EUS when we evaluated the possibility of endoscopic drainage in both patients. Interventional embolization was recommended as the first procedure to decrease the risk of bleeding. After that, EUS-guided transluminal drainage was successfully conducted, without vascular rupture. No postoperative complications occurred during hospitalization, and no recurrence was detected at the last follow-up CT scan performed at 1 mo. CONCLUSION: Interventional embolization is a safe, preoperative procedure that is performed before EUS-guided drainage in PFC patients with gastric varices or at high risk of bleeding.

Probing the activity of transition metal M and heteroatom N4 co-doped in vacancy fullerene (M-N4-C64, M = Fe, Co, and Ni) towards the oxygen reduction reaction by density functional theory.

In this study, a novel type oxygen reduction reaction (ORR) electrocatalyst is explored using density functional theory (DFT); the catalyst consists of transition metal M and heteroatom N4 co-doped in vacancy fullerene (M-N4-C64, M = Fe, Co, and Ni). Mulliken charge analysis shows that the metal center is the reaction site of ORR. PDOS analysis indicates that in M-N4-C64, the interaction between Fe-N4-C64 and the adsorbate is the strongest, followed by Co-N4-C64 and Ni-N4-C64. This is consistent with the calculated adsorption energies. By analyzing and comparing the adsorption energies of ORR intermediates and activation energies and reaction energies of all elemental reactions in M-N4-C64 (M = Fe, Co, and Ni), two favorable ORR electrocatalysts, Fe-N4-C64 and Co-N4-C64, are selected. Both exhibited conduction through the more efficient 4e- reduction pathway. Moreover, PES diagrams indicate that the whole reaction energy variation in the favorable ORR pathways of Fe-N4-C64 and Co-N4-C64 is degressive, which is conducive to positive-going reactions. This study offers worthwhile information for the improvement of cathode materials for fuel cells.

CLiAl2E and CLi2AlE (E = P, As, Sb, Bi): Planar Tetracoordinate Carbon Clusters with 16 and 14 Valence Electrons.

The strategy to remove the lone pairs of ligands combined with the bonding similarity between Li and Al have been utilized to design new planar tetracoordinate carbon (ptC) species C 2v CLiAl2E and CLi2AlE based on ptC global minima CAl3E (E = P, As, Sb, Bi) clusters. The explorations of potential energy surfaces and high-level CCSD(T) calculations indicate that these planar tetracoordinate carbon (ptC) species with 16 and 14 valence electrons (ve) are the global minima except for CLiAl2P. Bonding analyses reveal that there is one π and three σ bonds between C and ligands, one delocalized σ bond between the peripheral ligands, and three/two lone pairs for CLiAl2E and CLi2AlE (E = P, As, Sb, Bi). Especially, the C=E double bonds are crucial for the stabilities of these ptC clusters. The ptC core is governed by 2π + 6σ bonding, which conforms to the 8-electron counting. Born-Oppenheimer molecular dynamics (BOMD) simulations reveal that CLiAl2E and CLi2AlE (E = P, As, Sb, Bi) clusters are robust against isomerization and decomposition. The results obtained in this work complete the series of ptC CLi n Al3-n E (E = P, As, Sb, Bi; n = 0-3) systems and 18ve, 16ve, 14ve, and 12ve counting.