Noninvasive In Vivo Thrombus Imaging in Patients With Ischemic Stroke or Transient Ischemic Attack-Brief Report.

BACKGROUND: 18F-GP1 is a novel positron-emitting radiotracer that is highly specific for activated platelets and thrombus. In a proof-of-concept study, we aimed to determine its potential clinical application in establishing the role and origin of thrombus in ischemic stroke. METHODS: Eleven patients with recent ischemic stroke (n=9) or transient ischemic attack (n=2) underwent 18F-GP1 positron emission tomography and computed tomography angiography at a median of 11 (range, 2-21) days from symptom onset. 18F-GP1 uptake (maximum target-to-background ratio) was assessed in the carotid arteries and brain. RESULTS: 18F-GP1 uptake was identified in 10 of 11 patients: 4 in the carotid arteries only, 3 in the brain only, and 3 in both the brain and carotid arteries. In those with carotid uptake, 4 participants had >50% stenosis and 3 had nonstenotic disease. One case had bilateral stenotic disease (>70%), but only the culprit carotid artery demonstrated 18F-GP1 uptake. The average uptake was higher in the culprit (median maximum target-to-background ratio, 1.55 [interquartile range, 1.26-1.82]) compared with the contralateral nonculprit carotid artery (maximum target-to-background ratio, 1.22 [1.19-1.6]). In those with brain 18F-GP1 uptake (maximum target-to-background ratio, 6.45 [4.89-7.65]), areas of acute infarction on computed tomography correlated with brain 18F-GP1 uptake in 6 cases. Ex vivo autoradiography of postmortem infarcted brain tissue showed focal uptake corresponding to intraluminal thrombus within the culprit vessel and downstream microvasculature. There was also evidence of diffuse uptake within some of the infarcted brain tissue reflecting parenchymal petechial hemorrhage. CONCLUSIONS: 18F-GP1 positron emission tomography and computed tomography angiography is a novel noninvasive method of identifying in vivo cerebrovascular thrombosis, which holds major promise in understanding the role and origin of thrombosis in stroke. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03943966.

Translational molecular imaging: Thrombosis imaging with positron emission tomography.

A key focus of cardiovascular medicine is the detection, treatment, and prevention of disease, with a move towards more personalized and patient-centred treatments. To achieve this goal, novel imaging approaches that allow for early and accurate detection of disease and risk stratification are needed. At present, the diagnosis, monitoring, and prognostication of thrombotic cardiovascular diseases are based on imaging techniques that measure changes in structural anatomy and biological function. Molecular imaging is emerging as a new tool for the non-invasive detection of biological processes, such as thrombosis, that can improve identification of these events above and beyond current imaging modalities. At the forefront of these evolving techniques is the use of high-sensitivity radiotracers in conjunction with positron emission tomography imaging that could revolutionise current diagnostic paradigms by improving our understanding of the role and origin of thrombosis in a range of cardiovascular diseases.

Effect of Denosumab or Alendronic Acid on the Progression of Aortic Stenosis: A Double-Blind Randomized Controlled Trial.

BACKGROUND: Valvular calcification is central to the pathogenesis and progression of aortic stenosis, with preclinical and observational studies suggesting that bone turnover and osteoblastic differentiation of valvular interstitial cells are important contributory mechanisms. We aimed to establish whether inhibition of these pathways with denosumab or alendronic acid could reduce disease progression in aortic stenosis. METHODS: In a single-center, parallel group, double-blind randomized controlled trial, patients >50 years of age with calcific aortic stenosis (peak aortic jet velocity >2.5 m/s) were randomized 2:1:2:1 to denosumab (60 mg every 6 months), placebo injection, alendronic acid (70 mg once weekly), or placebo capsule. Participants underwent serial assessments with Doppler echocardiography, computed tomography aortic valve calcium scoring, and 18F-sodium fluoride positron emission tomography and computed tomography. The primary end point was the calculated 24-month change in aortic valve calcium score. RESULTS: A total of 150 patients (mean age, 72±8 years; 21% women) with calcific aortic stenosis (peak aortic jet velocity, 3.36 m/s [2.93-3.82 m/s]; aortic valve calcium score, 1152 AU [655-2065 AU]) were randomized and received the allocated trial intervention: denosumab (n=49), alendronic acid (n=51), and placebo (injection n=25, capsule n=25; pooled for analysis). Serum C-terminal telopeptide, a measure of bone turnover, halved from baseline to 6 months with denosumab (0.23 [0.18-0.33 µg/L] to 0.11 µg/L [0.08-0.17 µg/L]) and alendronic acid (0.20 [0.14-0.28 µg/L] to 0.09 µg/L [0.08-0.13 µg/L]) but was unchanged with placebo (0.23 [0.17-0.30 µg/L] to 0.26 µg/L [0.16-0.31 µg/L]). There were no differences in 24-month change in aortic valve calcium score between denosumab and placebo (343 [198-804 AU] versus 354 AU [76-675 AU]; P=0.41) or alendronic acid and placebo (326 [138-813 AU] versus 354 AU [76-675 AU]; P=0.49). Similarly, there were no differences in change in peak aortic jet velocity or 18F-sodium fluoride aortic valve uptake. CONCLUSIONS: Neither denosumab nor alendronic acid affected progression of aortic valve calcification in patients with calcific aortic stenosis. Alternative pathways and mechanisms need to be explored to identify disease-modifying therapies for the growing population of patients with this potentially fatal condition. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02132026.

Native Aortic Valve Disease Progression and Bioprosthetic Valve Degeneration in Patients With Transcatheter Aortic Valve Implantation.

BACKGROUND: Major uncertainties remain regarding disease activity within the retained native aortic valve, and regarding bioprosthetic valve durability, after transcatheter aortic valve implantation (TAVI). We aimed to assess native aortic valve disease activity and bioprosthetic valve durability in patients with TAVI in comparison with subjects with bioprosthetic surgical aortic valve replacement (SAVR). METHODS: In a multicenter cross-sectional observational cohort study, patients with TAVI or bioprosthetic SAVR underwent baseline echocardiography, computed tomography angiography, and 18F-sodium fluoride (18F-NaF) positron emission tomography. Participants (n=47) were imaged once with 18F-NaF positron emission tomography/computed tomography either at 1 month (n=9, 19%), 2 years (n=22, 47%), or 5 years (16, 34%) after valve implantation. Patients subsequently underwent serial echocardiography to assess for changes in valve hemodynamic performance (change in peak aortic velocity) and evidence of structural valve dysfunction. Comparisons were made with matched patients with bioprosthetic SAVR (n=51) who had undergone the same imaging protocol. RESULTS: In patients with TAVI, native aortic valves demonstrated 18F-NaF uptake around the outside of the bioprostheses that showed a modest correlation with the time from TAVI (r=0.36, P=0.023). 18F-NaF uptake in the bioprosthetic leaflets was comparable between the SAVR and TAVI groups (target-to-background ratio, 1.3 [1.2-1.7] versus 1.3 [1.2-1.5], respectively; P=0.27). The frequencies of imaging evidence of bioprosthetic valve degeneration at baseline were similar on echocardiography (6% versus 8%, respectively; P=0.78), computed tomography (15% versus 14%, respectively; P=0.87), and positron emission tomography (15% versus 29%, respectively; P=0.09). Baseline 18F-NaF uptake was associated with a subsequent change in peak aortic velocity for both TAVI (r=0.7, P<0.001) and SAVR (r=0.7, P<0.001). On multivariable analysis, 18F-NaF uptake was the only predictor of peak velocity progression (P<0.001). CONCLUSIONS: In patients with TAVI, native aortic valves demonstrate evidence of ongoing active disease. Across imaging modalities, TAVI degeneration is of similar magnitude to bioprosthetic SAVR, suggesting comparable midterm durability. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02304276.

Digital single-operator cholangioscope for endoscopic retrograde appendicitis therapy.

BACKGROUND: This study aimed to investigate the diagnostic and therapeutic value of a digital single-operator cholangioscope (SOC) system for endoscopic management of acute appendicitis. METHODS: 14 patients with acute uncomplicated simple or supportive appendicitis were evaluated between November 2018 and September 2020. The diagnosis of acute appendicitis was confirmed by direct colonoscopy imaging and cholangioscope. The success rate of digital SOC-assisted endoscopic retrograde appendicitis therapy (ERAT), the procedure time, postoperative length of hospital stay, complications, and recurrence rate were recorded. RESULTS: Technical success rate was 100 %, with high quality imaging of the appendiceal cavity achieved using SOC in all 14 patients. The mean procedure time was 37.8 (standard deviation [SD] 22) minutes. All patients experienced immediate relief from abdominal pain after the procedure. Mean postoperative hospitalization was 1.9 (SD 0.7) days. No recurrence occurred during 2-24 months of follow-up. CONCLUSION: Digital SOC-assisted ERAT provided a feasible, safe, and effective alternative approach for diagnosis and management of acute uncomplicated appendicitis without the need for X-ray or ultrasonic guidance.

Quantifying microcalcification activity in the thoracic aorta.

BACKGROUND: Standard methods for quantifying positron emission tomography (PET) uptake in the aorta are time consuming and may not reflect overall vessel activity. We describe aortic microcalcification activity (AMA), a novel method for quantifying 18F-sodium fluoride (18F-NaF) uptake in the thoracic aorta. METHODS: Twenty patients underwent two hybrid 18F-NaF PET and computed tomography (CT) scans of the thoracic aorta less than three weeks apart. AMA, as well as maximum (TBRmax) and mean (TBRmean) tissue to background ratios, were calculated by two trained operators. Intra-observer repeatability, inter-observer repeatability and scan-rescan reproducibility were assessed. Each 18F-NaF quantification method was compared to validated cardiovascular risk scores. RESULTS: Aortic microcalcification activity demonstrated excellent intra-observer (intraclass correlation coefficient 0.98) and inter-observer (intraclass correlation coefficient 0.97) repeatability with very good scan-rescan reproducibility (intraclass correlation coefficient 0.86) which were similar to previously described TBRmean and TBRmax methods. AMA analysis was much quicker to perform than standard TBR assessment (3.4min versus 15.1min, P<0.0001). AMA was correlated with Framingham stroke risk scores and Framingham risk score for hard cononary heart disease. CONCLUSIONS: AMA is a simple, rapid and reproducible method of quantifying global 18F-NaF uptake across the ascending aorta and aortic arch that correlates with cardiovascular risk scores.

ATF2 accelerates the invasion and metastasis of hepatocellular carcinoma through targeting the miR-548p/TUFT1 axis.

AIM: Due to high invasion and metastasis, hepatocellular carcinoma (HCC) is known as one of the most fatal carcinomas. We aim to further investigate regulatory mechanisms of invasion and metastasis to elucidate HCC pathogenesis and develop novel medications. METHODS: Patient specimens were collected for assessing gene expression and correlation between gene expressions. The expression of Ki67 and E-cadherin in subcutaneous xenograft tumor were examined by immunohistochemistry staining. The expression of activating transcription factor 2 (ATF2), miR-548p and TUFT1 were determined using Real-time quantitative reverse transcription polymerase chain reaction. Epithelial-mesenchymal transition and PI3K/AKT signaling-associated markers were examined with western blot. The proliferation, migration and invasion were assessed by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide, colony formation and transwell assays, respectively. Cell apoptosis was assessed via Annexin V and propidium iodide staining. Gene interaction was confirmed using chromatin immunoprecipitation and luciferase activity assays. Subcutaneous and intravenous xenograft mouse models were established for analyzing HCC growth and metastasis in vivo. RESULTS: ATF2 was up-regulated in HCC patients and cells. ATF2 promoted HCC cell proliferation, migration and invasion and inhibited cell apoptosis through directly targeting miR-548p and controlling its expression. miR-548p suppressed HCC cell proliferation, migration and invasion and enhanced cell apoptosis. miR-548p directly bound to the 3'UTR of TUFT1 to restrain its expression and subsequently suppress the PI3K/AKT signaling. ATF2 knock-down significantly suppressed the growth and metastasis of HCC. CONCLUSION: ATF2 accelerates HCC progression by promoting cell proliferation, migration, invasion and metastasis, which is dependent on regulating the miR-548p/TUFT1 axis.

Shape memory of a polymer grating surface fabricated by two-beam interference lithography.

Switchable and reversible optical elements have potential applications in self-adaptive optics. Shape-memory polymer devices with adaptive properties could be easily switched under environment or field stimuli. Here, the laser beam interference technique was used to realize the periodic grating structures of the shape-memory polymer, and memory and recovery of the grating structures were performed. A one-dimensional grating structure was fabricated from dual-beam interference lithography of a nanosecond laser and underwent pressure in a condition of 195°C. The vertical height of the grating was reduced, and the diffraction light was weakened. When the sample was cooled down to room temperature, the morphology of the grating could be kept. After raising the ambient temperature of the sample to 120°C, the morphology of the grating was recovered to the original state, which realized the shape-memory function.

Progress of HOTAIR-microRNA in hepatocellular carcinoma.

The Hox transcript antisense intergenic RNA (HOTAIR) has been identified as a tumor gene, and its expression in HCC is significantly increased. HOTAIR is associated with the proliferation, invasion, metastasis and poor prognosis of HCC. In addition, HOTAIR can also regulate the expression and function of microRNA by recruiting the polycomb repressive complex 2 (PRC2) and competitive adsorption, thus promoting the occurrence and development of HCC. In this review, we discussed the two mechanisms of HOTAIR regulating miRNA through direct binding miRNA and indirect regulation, and emphasized the role of HOTAIR in HCC through miRNA, explained the regulatory pathway of HOTAIR-miRNA-mRNA and introduced the role of this pathway in HCC proliferation, drug resistance, invasion and metastasis.

Incidence, Microbiology, and Outcomes in Patients Hospitalized With Infective Endocarditis.

BACKGROUND: Despite improvements in management, infective endocarditis remains associated with high mortality and morbidity. We describe temporal changes in the incidence, microbiology, and outcomes of infective endocarditis and the effect of changes in national antibiotic prophylaxis guidelines on incident infective endocarditis. METHODS: Using a Scotland-wide, individual-level linkage approach, all patients hospitalized with infective endocarditis from 1990 to 2014 were identified and linked to national microbiology, prescribing, and morbidity and mortality datasets. Linked data were used to evaluate trends in the crude and age- and sex-adjusted incidence and outcomes of infective endocarditis hospitalizations. From 2008, microbiology data and associated outcomes adjusted for patient demographics and comorbidity were also analyzed. An interrupted time series analysis was performed to evaluate incidence before and after changes to national antibiotic prophylaxis guidelines. RESULTS: There were 7638 hospitalizations (65±17 years, 51% females) with infective endocarditis. The estimated crude hospitalization rate increased from 5.3/100 000 (95% CI, 4.8-5.9) to 8.6/100 000 (95% CI, 8.1-9.1) between 1990 and 1995 but remained stable thereafter. There was no change in crude incidence following the 2008 change in antibiotic prophylaxis guidelines (relative risk of change 1.06 [95% CI, 0.94-1.20]). The incidence rate in patients >80 years of age doubled from 1990 to 2014 (17.7/100 000 [95% CI, 13.4-23.3] to 37.9/100 000 [95% CI, 31.5-45.5]). The predicted 1-year age- and comorbidity-adjusted case fatality rate for a 65-year-old patient decreased in women (27.3% [95% CI, 24.6-30.2] to 23.7% [95% CI, 21.1-26.6]) and men (30.7% [95% CI, 27.7-33.8] to 26.8% [95% CI, 24.0-29.7]) from 1990 to 2014. Blood culture data were available from 2008 (n=2267/7638, 30%), with positive blood cultures recorded in 42% (950/2267). Staphylococcus (403/950, 42.4%) and streptococcus (337/950, 35.5%) species were most common. Staphylococcus aureus and enterococcus had the highest 1-year mortality (adjusted odds ratio 4.34 [95% CI, 3.12-6.05] and 3.41 [95% CI, 2.04-5.70], respectively). CONCLUSIONS: Despite changes in antibiotic prophylaxis guidelines, the crude incidence of infective endocarditis has remained stable. However, the incidence rate has doubled in the elderly. Positive blood cultures were observed in less than half of patients, with Staphylococcus aureus and enterococcus bacteremia associated with worse outcomes.

Advancing flexible endoscopy to natural orifice transluminal endoscopic surgery.

PURPOSE OF REVIEW: This review is an update on the recent advancements and clinical applications of flexible endoscopy in the context of natural orifice translumenal endoscopic surgery (NOTES). We focus on recent developments in gastrointestinal luminal and transluminal NOTES. RECENT FINDINGS: NOTES has evolved from a hybrid approach utilizing a laparoscopic assistant to pure NOTES without laparoscopic assistance. Current experimental and clinical studies focus on the implementation of new minimally invasive approaches as well as on the training in the use of these procedures. In recent years, flexible endoscopic-NOTES and endoluminal surgery have increasingly reported favorable results in preclinical and experimental settings using flexible endoscopic cholecystectomy, cholecystolithotomy, and appendectomy. Additionally, flexible endoscopic lymphadenectomy and thyroidectomy are among the new interventions that are opening new frontiers for endoscopists to explore. SUMMARY: Flexible endoscopy has paved way to new frontiers for endoscopists and surgeons. As the armamentarium of interventional endoscopy increases and the ability of endoscopists to perform advanced interventions safely fosters an inevitable step forward that will involve the integration of new technology with innovative thinking.

First-phase ejection fraction by cardiovascular magnetic resonance predicts outcomes in aortic stenosis.

BACKGROUND: First-phase ejection fraction (EF1; the ejection fraction measured during active systole up to the time of maximal aortic flow) measured by transthoracic echocardiography (TTE) is a powerful predictor of outcomes in patients with aortic stenosis. We aimed to assess whether cardiovascular magnetic resonance (CMR) might provide more precise measurements of EF1 than TTE and to examine the correlation of CMR EF1 with measures of fibrosis. METHODS: In 141 patients with at least mild aortic stenosis, we measured CMR EF1 from a short-axis 3D stack and compared its variability with TTE EF1, and its associations with myocardial fibrosis and clinical outcome (aortic valve replacement (AVR) or death). RESULTS: Intra- and inter-observer variation of CMR EF1 (standard deviations of differences within and between observers of 2.3% and 2.5% units respectively) was approximately 50% that of TTE EF1. CMR EF1 was strongly predictive of AVR or death. On multivariable Cox proportional hazards analysis, the hazard ratio for CMR EF1 was 0.93 (95% confidence interval 0.89-0.97, p = 0.001) per % change in EF1 and, apart from aortic valve gradient, CMR EF1 was the only imaging or biochemical measure independently predictive of outcome. Indexed extracellular volume was associated with AVR or death, but not after adjusting for EF1. CONCLUSIONS: EF1 is a simple robust marker of early left ventricular impairment that can be precisely measured by CMR and predicts outcome in aortic stenosis. Its measurement by CMR is more reproducible than that by TTE and may facilitate left ventricular structure-function analysis.

Many-particle induced band renormalization processes in few- and mono-layer MoS2.

Band renormalization effects play a significant role for two-dimensional (2D) materials in designing a device structure and customizing their optoelectronic performance. However, the intrinsic physical mechanism about the influence of these effects cannot be revealed by general steady-state studies. Here, band renormalization effects in organic superacid treated monolayer MoS2, untreated monolayer MoS2and few-layer MoS2are quantitatively analyzed by using broadband femtosecond transient absorption spectroscopy. In comparison with the untreated monolayer, organic superacid treated monolayer MoS2maintains a direct bandgap structure with two thirds of carriers populated at K valley, even when the initial exciton density is as high as 2.05 × 1014cm-2(under 400 nm excitations). While for untreated monolayer and few-layer MoS2, many-particle induced band renormalizations lead to a stronger imbalance for the carrier population between K and Q valleys inkspace, and the former experiences a direct-to-indirect bandgap transition when the initial exciton density exceeds 5.0 × 1013cm-2(under 400 nm excitations). Those many-particle induced band renormalization processes further suggest a band-structure-controlling method in practical 2D devices.

Trion dynamics and charge photogeneration in MoS2 nanosheets prepared by liquid phase exfoliation.

Since excitonic quasiparticles, including excitons, trions and charges, have a great influence on the photoelectric characteristics of two-dimensional (2D) transition metal dichalcogenides (TMDs), systematic explorations of the trion dynamics and charge photogeneration in 2D TMDs are important for their future optoelectronic applications. Here, broadband femtosecond transient absorption spectroscopic experiments are performed first to investigate the peak shifting and broadening kinetics in MoS2 nanosheets in solution prepared by liquid phase exfoliation (LPE-MoS2, ∼9 layers, 9L), which reveal that the binding energies for the A-, B-, and C-exciton states are ∼77 meV, ∼76 meV, and -70 meV (the energy difference between free charges and excitons; the negative sign for C-excitons means a spontaneous dissociation nature in band-nesting regions), respectively. Then, the trion dynamics and charge photogeneration in LPE-MoS2 nanosheets have been studied in detail, demonstrating that they are comparable to those in chemical vapor deposition grown MoS2 films (1L-, 3L- and 7L-MoS2). These experimental results suggest that LPE-TMD nanosheets also have the potential for use in charge-related optoelectronic devices based on 2D TMDs.

Primacy of coronary CT angiography as the gatekeeper for the cardiac catheterization laboratory.

Determining the underlying etiology of chest pain remains a mainstay of modern cardiological practice and is focused on identifying coronary artery disease to improve both symptoms and prognosis. In the current age of multi-modality imaging, the expanding repertoire of tests has subjected clinicians to a tyranny of choices. In whom should we perform further investigations? What non-invasive modality should be used? Which test is the best gatekeeper for invasive coronary angiography? In this week's American Heart Journal, Houssany-Pissot and colleagues present real-world data from a large French cohort of patients who present with suspected stable coronary artery disease undergoing invasive coronary angiography. Their findings demonstrate that compared to functional testing, coronary computed tomography angiography is associated with fewer normal invasive coronary angiograms and more patients with actionable disease. Moreover, this was apparent irrespective of the pre-test probability of obstructive coronary artery disease. The consistency of this study with data from randomised trials and observational registries leads us to agree that computed tomography has primacy as gatekeeper for the cardiac catheter laboratory irrespective of the level of pre-test probability. This latest addition to the growing and large body of evidence does beg the question of why guidelines do not now recommend CCTA as the first line test of choice for the non-invasive investigation of all patients with stable coronary artery disease?

Novel transcription regulatory sequences and factors of the immune evasion protein ICP47 (US12) of herpes simplex viruses.

BACKGROUND: Herpes simplex virus (HSV) can cause encephalitis. Its infected cell polypeptide 47 (ICP47), encoded by immediate-early gene US12, promotes immune escape. ICP47 was modified in the clinically approved oncolytic HSV (oHSV) T-Vec. However, transcription regulatory sequence (TRS) and transcription regulatory factor (TRF) of HSV US12 are seldom reported. METHODS: Previously, our laboratory isolated a new HSV strain named HSV-1-LXMW from a male patient with oral herpes in Beijing, China. Firstly, the genetic tree was used to analyze its genetic relationship. The US12 TRS and TRF in HSV-1-LXMW were found by using predictive software. Secondly, the further verification by the multi-sequence comparative analysis shown that the upstream DNA sequence of HSV US12 gene contained the conserved region. Finally, the results of literature search shown that the expression of transcription factors was related to the tissue affinity of HSV-1 and HSV-2, so as to increase the new understanding of the transcriptional regulation of HSV biology and oncolytic virus (OVs) therapy. RESULTS: Here we reported the transcriptional regulation region sequence of our new HSV-1-LXMW, and its close relationship with HSV-1-CR38 and HSV-1-17. Importantly we identified eight different kinds of novel TRSs and TRFs of HSV US12 for the first time, and found they are conserved among HSV-1 (c-Rel, Elk-1, Pax-4), HSV-2 (Oct-1, CF2-II, E74A, StuAp) or both HSVs (HNF-4). The TRFs c-Rel and Oct-1 are biologically functional respectively in immune escape and viral replication during HSV infection. CONCLUSIONS: Our findings have important implication to HSV biology, infection, immunity and oHSVs.

Correction to: Aortic valve and coronary 18F-sodium fluoride activity: a common cause?

The article "Aortic valve and coronary 18F-sodium fluoride activity: a common cause?", written by Rong Bing and Marc R. Dweck, was originally published electronically on the publisher's internet portal (currently SpringerLink) on 27 September 2019 with open access. With the author(s)' decision to step back from Open Choice, the copyright of the article changed on 18 November 2019 to © American Society of Nuclear Cardiology 2019 and the article is forthwith distributed under the terms of copyright.

A snare-assisted pure NOTES retrograde cholecystectomy using a single channel flexible endoscope: a pilot experiment in a porcine model.

BACKGROUND AND AIM: Natural orifice transluminal endoscopic surgery (NOTES) cholecystectomy is an emerging technology. Interest is ongoing and developments have been rapid but NOTES cholecystectomy has failed to gain traction. Here, we share our experience of snare-assisted pure NOTES retrograde cholecystectomy using porcine models. MATERIALS AND METHODS: Under general anesthesia, an incision was created on the posterior vagina wall and an endoscope with a snare attached to the transparent cap was introduced into the pelvic cavity and then upward into peritoneal cavity. After locating the liver and gallbladder, the fundic wall of gallbladder was grasped using a biopsy forceps and the snare was released to ligate the fundus. The gallbladder was then carefully dissected from the gallbladder bed using hook/IT knives with the assistance of the snare. The cystic duct and cystic artery were identified, clipped twice and isolated from the gallbladder using the hook knife to cut between the clips. The specimen was then removed through the vagina using the snare. RESULTS: This procedure was successfully performed in 8 consecutive pigs. The average procedure time was 53 min (range 40-60 min). No severe bleeding or other complication was observed either during or after the procedure. Normal diets were given on the same day of the procedure. All animals recovered uneventfully. CONCLUSION: We successfully performed snare-assisted pure NOTES retrograde cholecystectomy in pigs using standard endoscopic instruments. In our experience, pure NOTES cholecystectomy using the retrograde approach performed with a single channel flexible endoscope proved safe and feasible with a short procedure time and quick recovery. The translation of this technique to human subjects seems straight forward and provides a new fitting path to pure NOTES.

Mucosal loss as a critical factor in esophageal stricture formation after mucosal resection: a pilot experiment in a porcine model.

BACKGROUND AND AIM: Esophageal stricture is a major complication of large areas endoscopic submucosal dissection (ESD). Until now, the critical mechanism of esophageal stricture remains unclear. We examined the role of mucosal loss versus submucosal damage in esophageal stricture formation after mucosal resection using a porcine model. MATERIALS AND METHODS: Twelve swine were randomly divided into two groups, each of 6. In each group, two 5-cm-long submucosal tunnels were made to involve 1/3rd of the widths of the anterior and posterior esophageal circumference. The entire mucosal roofs of both tunnels were resected in group A. In group B, the tunnel roof mucosa was incised longitudinally along the length of the tunnel, but without excision of any mucosa. Stricture formation was evaluated by endoscopy after 1, 2, and 4 weeks, respectively. Anatomical and histological examinations were performed after euthanasia. RESULTS: Healing observed on endoscopy in both groups after 1 week. Group A (mucosa resected) developed mild-to-severe esophageal stricture, dysphagia, and weight loss. In contrast, no esophageal stricture was evident in group B (mucosa incisions without resection) after 2 and 4 weeks, respectively. Macroscopic examination showed severe esophageal stricture and shortening of esophagus in only group A. Inflammation and fibrous hyperplasia of the submucosal layer was observed on histological examination in both groups. CONCLUSION: The extent of loss of esophageal mucosa appears to be a critical factor for esophageal stricture. Inflammation followed by fibrosis may contribute to alteration in compliance of the esophagus but is not the main mechanism of postresection stricture.