Defining the optimal technique for endoscopic ultrasound shear wave elastography: a combined benchtop and animal model study with comparison to transabdominal shear wave elastography

Background/Aims Shear wave elastography (SWE) is used for liver fibrosis staging based on stiffness measurements. It can be performed using endoscopic ultrasound (EUS) or a transabdominal approach. Transabdominal accuracy can be limited in patients with obesity because of the thick abdomen. Theoretically, EUS-SWE overcomes this limitation by internally assessing the liver. We aimed to define the optimal technique for EUS-SWE for future research and clinical use and compare its accuracy with that of transabdominal SWE. Methods Benchtop study: A standardized phantom model was used. The compared variables included the region of interest (ROI) size, depth, and orientation and transducer pressure. Porcine study: Phantom models with varying stiffness values were surgically implanted between the hepatic lobes. Results For EUS-SWE, a larger ROI size of 1.5 cm and a smaller ROI depth of 1 cm demonstrated a significantly higher accuracy. For transabdominal SWE, the ROI size was nonadjustable, and the optimal ROI depth ranged from 2 to 4 cm. The transducer pressure and ROI orientation did not significantly affect the accuracy. There were no significant differences in the accuracy between transabdominal SWE and EUS-SWE in the animal model. The variability among the operators was more pronounced for the higher stiffness values. Small lesion measurements were accurate only when the ROI was entirely situated within the lesion. Conclusions We defined the optimal viewing windows for EUS-SWE and transabdominal SWE. The accuracy was comparable in the non-obese porcine model. EUS-SWE may have a higher utility for evaluating small lesions than transabdominal SWE

AGA Clinical Practice Update on interventional EUS for vascular investigation and therapy: Commentary

DESCRIPTION: The purpose of this AGA Institute Clinical Practice Update is to review the available evidence supporting and examine opportunities for future research in endoscopic ultrasound-guided vascular investigation and therapies. METHODS: This Clinical Practice Update was commissioned and approved by the AGA Institute Clinical Practice Updates Committee and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the Clinical Practice Updates Committee and external peer review through standard procedures of Clinical Gastroenterology and Hepatology. This expert commentary incorporates important as well as recently published studies in this field, and it reflects the experiences of the authors who are advanced endoscopists with expertise in endoscopic ultrasound-guided vascular investigation and therapy

Controlling gene expression in mycobacteria with anhydrotetracycline and Tet repressor

Gene expression systems that allow the regulation of bacterial genes during an infection are valuable molecular tools but are lacking for mycobacterial pathogens. We report the development of mycobacterial gene regulation systems that allow controlling gene expression in fast and slow-growing mycobacteria, including Mycobacterium tuberculosis, using anhydrotetracycline (ATc) as inducer. The systems are based on the Escherichia coli Tn10-derived tet regulatory system and consist of a strong tet operator (tetO)-containing mycobacterial promoter, expression cassettes for the repressor TetR and the chemical inducer ATc. These systems allow gene regulation over two orders of magnitude in Mycobacterium smegmatis and M.tuberculosis. TetR-controlled gene expression was inducer concentration-dependent and maximal with ATc concentrations at least 10- and 20-fold below the minimal inhibitory concentration for M.smegmatis and M.tuberculosis, respectively. Using the essential mycobacterial gene ftsZ, we showed that these expression systems can be used to construct conditional knockouts and to analyze the function of essential mycobacterial genes. Finally, we demonstrated that these systems allow gene regulation in M.tuberculosis within the macrophage phagosome

Endoscopic Ultrasound-Guided Fine Needle Aspiration and Endoscopic Retrograde Cholangiopancreatography-Based Tissue Sampling in Suspected Malignant Biliary Strictures: A Meta-Analysis of Same-Session Procedures

Background/Aims: The diagnosis of biliary strictures can be challenging. There are no systematic reviews studying same-session endoscopic retrograde cholangiopancreatography (ERCP)-based tissue sampling and endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for the diagnosis of biliary strictures. Methods: A systematic review was conducted on studies analyzing same-session EUS and ERCP for tissue diagnosis of suspected malignant biliary strictures. The primary outcome was the accuracy of each method individually compared to the two methods combined. The secondary outcome was the accuracy of each method in pancreatic and biliary etiologies. In the meta-analysis, we used Forest plots, summary receiver operating characteristic curves, and estimates of the area under the curve for intention-to-treat analysis. Results: Of the 12,132 articles identified, six were included, resulting in a total of 497 patients analyzed. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and accuracy of the association between the two methods were: 86%, 98%, 12.50, 0.17, and 96.5%, respectively. For the individual analysis, the sensitivity, specificity and accuracy of EUS-FNA were 76%, 100%, and 94.5%, respectively; for ERCP-based tissue sampling, the sensitivity, specificity, and accuracy were 58%, 98%, and 78.1%, respectively. For pancreatic lesions, EUS-FNA was superior to ERCP-based tissue sampling. However, for biliary lesions, both methods had similar sensitivities. Conclusions: Same-session EUS-FNA and ERCP-based tissue sampling is superior to either method alone in the diagnosis of suspected malignant biliary strictures. Considering these results, combination sampling should be performed when possible