Extension of the thermal porosimetry method to high gas pressure for nanoporosimetry estimation

Standard pore size determination methods like mercury porosimetry, nitrogen sorption, microscopy, or X-ray tomography are not suited to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization has been developed in a previous study. This method has been used with air pressure varying from 10^-1 to 10⁵ Pa for materials having a thermal conductivity less than 0.05 W m^-1 K^-1 at atmospheric pressure. It enables the estimation of pore size distribution between 100 nm and 1 mm. In this paper, we present a new experimental device enabling thermal conductivity measurement under gas pressure up to 10⁶ Pa, enabling the estimation of the volume fraction of pores having a 10 nm diameter. It is also demonstrated that the main thermal conductivity models (parallel, series, Maxwell, Bruggeman, self-consistent) lead to the same estimation of the pore size distribution as the extended parallel model (EPM) presented in this paper and then used to process the experimental data. Three materials with thermal conductivities at atmospheric pressure ranging from 0.014 W m^-1 K^-1 to 0.04 W m^-1 K^-1 are studied. The thermal conductivity measurement results obtained with the three materials are presented, and the corresponding pore size distributions between 10 nm and 1 mm are presented and discussed.

Genetic and pharmacological inhibition of microRNA-92a maintains podocyte cell cycle quiescence and limits crescentic glomerulonephritis

Crescentic rapidly progressive glomerulonephritis (RPGN) represents the most aggressive form of acquired glomerular disease. While most therapeutic approaches involve potentially toxic immunosuppressive strategies, the pathophysiology remains incompletely understood. Podocytes are glomerular epithelial cells that are normally growth-arrested because of the expression of cyclin-dependent kinase (CDK) inhibitors. An exception is in RPGN where podocytes undergo a deregulation of their differentiated phenotype and proliferate. Here we demonstrate that microRNA-92a (miR-92a) is enriched in podocytes of patients and mice with RPGN. The CDK inhibitor p57^Kip2 is a major target of miR-92a that constitutively safeguards podocyte cell cycle quiescence. Podocyte-specific deletion of miR-92a in mice de-repressed the expression of p57^Kip2 and prevented glomerular injury in RPGN. Administration of an anti-miR-92a after disease initiation prevented albuminuria and kidney failure, indicating miR-92a inhibition as a potential therapeutic strategy for RPGN. We demonstrate that miRNA induction in epithelial cells can break glomerular tolerance to immune injury.

Crescentic rapidly progressive glomerulonephritis is a severe form of glomerula disease characterized by podocyte proliferation and migration. Here Henique et al. demonstrate that inhibition of miRNA-92a prevents kidney failure by promoting the expression of CDK inhibitor p57^Kip2 that regulates podocyte cell cycle.

Diagnosis of acute overt gastrointestinal bleeding with CT-angiography: Comparison of the diagnostic performance of individual acquisition phases

PURPOSE

To compare the respective values of arterial phase, portal venous phase and combination of phases using 64-section multidetector computed tomography (MDCT) for diagnosing acute overt gastrointestinal bleeding (AOGIB).

PATIENTS AND METHODS

Forty-nine patients with AOGIB were included. There were 30 men and 19 women, with a mean age of 65.4±15.6 (SD) years [range, 34-91years]. Two observers reviewed MDCT examinations in consensus for presence of active bleeding, location of bleeding site and nature of causative lesion. The different acquisition phases were reviewed independently.

RESULTS

AOGIB was identified in 28/49 patients (57%) with the multiphasic set, in 26/49 patients (53%) with arterial phase and in 25/49 patients (51%) with portal venous phase. Multiphasic set helped locate the bleeding site in 40/49 patients (82%). The cause was elucidated in 23/49 patients (47%) with multiphasic set. The differences between set performances were not statistically significant. Sensitivity for depicting AOGIB with the multiphasic set was 92% and specificity was 76%.

CONCLUSION

Multiphasic 64-section MDCT has high diagnostic performances in patients with AOGIB. Further studies with a larger population are needed to reach statistical significance and demonstrate better diagnostic performance of multiphasic MDCT in comparison with the arterial or portal phase alone.

Detection of small-bowel tumours with CT enteroclysis using carbon dioxide and virtual enteroscopy: A preliminary study

PURPOSE

The aim of this prospective study was to evaluate the feasibility, tolerance and performance of virtual enteroscopy (VE) using carbon dioxide for small-bowel distension in patients with suspected small-bowel tumours (SBTs).

PATIENTS AND METHODS

After IRB approval, 17 patients with suspected SBTs were prospectively included. Radiation dose was compared to 34 matched patients (2 for 1) for age, gender and body weight, who had undergone CT-enteroclysis with neutral contrast (CTE). Performance of VE was evaluated through comparison with the current standard of reference, including surgery and/or enteroscopy and/or follow-up.

RESULTS

Tolerance was excellent in 16/17 patients (94%). The radiation dose was lower for VE than for CTE (533 ± 282 vs. 974 ± 505 mGy.cm; p = 0.002). With VE, a total of 25 polyps >5 mm in size were depicted in 12/17 patients. On a per-lesion analysis, sensitivity and positive predictive value of VE were 92.0% and 92.0%, respectively. On a per-segment analysis VE had a sensitivity and specificity of 95.0% and 87.0%, respectively.

CONCLUSION

Our preliminary study suggests that VE is a feasible and well-tolerated technique with high sensitivity and specificity for the diagnosis of SBT.

KEY POINTS

• Virtual enteroscopy is feasible and well tolerated. • Virtual enteroscopy appears to be accurate for detection of small-bowel tumours. • Sensitivity and PPV of virtual enteroscopy is 92.0% and 92.0%. • Radiation dose is lower with virtual enteroscopy compared to MDCT-enteroclysis.

Endoscopic ultrasound-guided hepaticogastrostomy versus percutaneous transhepatic drainage for malignant biliary obstruction after failed endoscopic retrograde cholangiopancreatography: a retrospective expertise-based study from two centers

BACKGROUND

Percutaneous transhepatic biliary drainage (PTBD) is widely performed as a salvage procedure in patients with unresectable malignant obstruction of the common bile duct (CBD) after failed endoscopic retrograde cholangiopancreatography (ERCP) or in case of surgically altered anatomy. Endoscopic ultrasound-guided hepaticogastrostomy (EU-HGS) is a more recently introduced alternative to relieve malignant obstructive jaundice. The aim of this prospective observational study was to compare the outcome, efficacy and adverse events of EU-HGS and PTBD.

METHODS

From April 2012 to August 2015, consecutive patients with malignant CBD obstruction who underwent EU-HGS or PTBD in two tertiary-care referral centers were included. The primary endpoint was the clinical success rate. Secondary endpoints were technical success, overall survival, procedure-related adverse events, incidence of adverse events, and reintervention rate.

RESULTS

A total of 51 patients (EU-HGS, n = 31; PTBD, n = 20) were included. Median survival was 71 days (range 25-75th percentile; 30-95) for the EU-HGS group and 78 days (range 25-75th percentile; 42-108) for the PTBD group (p = 0.99). Technical success was achieved in all patients in both groups. Clinical success was achieved in 25 (86%) of 31 patients in the EU-HGS group and in 15 (83%) of 20 patients in the PTBD group (p = 0.88). There was no difference in adverse events rates between the two groups (EU-HGS: 16%; PTBD: 10%) (p = 0.69). Four deaths within 1 month (two hemorrhagic and two septic) were considered procedure related (two in the EU-HGS group and two in the PTBD group). Overall reintervention rate was significantly lower after EU-HGS (n = 2) than after PTBD (n = 21) (p = 0.0001). Length of hospital stay was shorter after EU-HGS (8 days versus 15 days; p = 0.002).

CONCLUSIONS

EU-HGS can be an effective and safe mini invasive-procedure alternative to PTBD, with similar success and adverse-event rates, but with lower rates of reintervention and length of hospitalization.

Self-assembling peptide matrix for the prevention of esophageal stricture after endoscopic resection: a randomized controlled trial in a porcine model

Esophageal stricture formation after extensive endoscopic resection remains a major limitation of endoscopic therapy for early esophageal neoplasia. This study assessed a recently developed self-assembling peptide (SAP) matrix as a wound dressing after endoscopic resection for the prevention of esophageal stricture. Ten pigs were randomly assigned to the SAP or the control group after undergoing a 5-cm-long circumferential endoscopic submucosal dissection of the lower esophagus. Esophageal diameter on endoscopy and esophagogram, weight variation, and histological measurements of fibrosis, granulation tissue, and neoepithelium were assessed in each animal. The rate of esophageal stricture at day 14 was 40% in the SAP-treated group versus 100% in the control group (P = 0.2). Median interquartile range (IQR) esophageal diameter at day 14 was 8 mm (2.5-9) in the SAP-treated group versus 4 mm (3-4) in the control group (P = 0.13). The median (IQR) stricture indexes on esophagograms at day 14 were 0.32 (0.14-0.48) and 0.26 (0.14-0.33) in the SAP-treated and control groups, respectively (P = 0.42). Median (IQR) weight variation during the study was +0.2 (-7.4; +1.8) and -3.8 (-5.4; +0.6) in the SAP-treated and control groups, respectively (P = 0.9). Fibrosis, granulation tissue, and neoepithelium were not significantly different between the groups. The application of SAP matrix on esophageal wounds after a circumferential endoscopic submucosal dissection delayed the onset of esophageal stricture in a porcine model.

Independent risk factors of 30-day outcomes in 1264 patients with peptic ulcer bleeding in the USA: large ulcers do worse

BACKGROUND

Predictors of worse outcomes (rebleeding, surgery and death) of peptic ulcer bleeds (PUBs) are essential indicators because of significant morbidity and mortality rates of PUBs. However those have been infrequently reported since changes in medical therapy (PPI, proton pump inhibitors) and application of newer endoscopic haemostatic technique.

AIMS

To determine: (i) independent risk factors for 30-day rebleeding, surgery, and death and (ii) whether ulcer size is an independent predictor of major outcomes in patients with severe PUB after successful endoscopic haemostasis and treatment with optimal medical (high dose IV PPI) vs. prior treatment (high dose IV histamine 2 antagonists - H2RAs).

METHODS

A large prospectively followed population of patients hospitalised with severe PUBs between 1993 and 2011 at two US tertiary care academic medical centres, stratified by stigmata of recent haemorrhage (SRH) was studied. Using multivariable logistic regression analyses, independent risk factors for each outcome (rebleeding, surgery and death) up to 30 days were analysed. Effects for medical treatment (H2RA patients 1993-2005 vs. PPIs 2006-2011) were also analysed.

RESULTS

A total of 1264 patients were included. For ulcers ≥10 mm, the odds of 30-day rebleeding increased 6% per each 10% increase in ulcer size (OR 1.06, 95% CI 1.02-1.10, P = 0.0053). Other risk factors for 30-day rebleeding were major SRH, in-patient start of bleeding, and prior GI bleeding. Major SRH and ulcer size≥10 mm were predictors of 30-day surgery. Risk factors for 30-day death were major SRH, in-patient bleeding, and any initial platelet transfusion or fresh frozen plasma transfusion ≥2 units. Among patients with major SRH and out-patient start of bleeding, larger ulcer size was also a risk factor for death (OR 1.08 per 10% increase in ulcer size, 95% CI 1.02-1.14, P = 0.0095). Ulcer size was a significant independent variable for both time periods.

CONCLUSIONS

Ulcer size is a risk factor for worse outcomes after PUB and should be carefully recorded at initial endoscopy to improve patient triage and management.

A self-assembling matrix-forming gel can be easily and safely applied to prevent delayed bleeding after endoscopic resections

BACKGROUND

Endoscopic resections have low morbidity and mortality. Delayed bleeding has been reported in approximately 1 - 15 % of cases, increasing with antiplatelet/anticoagulant therapy or portal hypertension. A self-assembling peptide (SAP) forming a gel could protect the mucosal defect during early healing. This retrospective trial aimed to assess the safety and efficacy of SAP in preventing delayed bleeding after endoscopic resections.

METHODS

Consecutive patients with endoscopic resections were enrolled in two tertiary referral centers. Patients with a high risk of bleeding (antiplatelet agents, anticoagulation drugs with heparin bridge therapy, and cirrhosis with portal hypertension) were also included. The SAP gel was applied immediately after resection to cover the whole ulcer bed.

RESULTS

In total, 56 patients were included with 65 lesions (esophagus [n = 8], stomach [n = 22], duodenum [n = 10], ampullary [n = 3], colon [n = 7], and rectum [n = 15]) in two centers. Among those 65 lesions, 29 were resected in high risk situations (9 uninterrupted aspirin therapy, 6 heparin bridge therapies, 5 cirrhosis and portal hypertension, 1 both cirrhosis and heparin bridge, 3 both cirrhosis and uninterrupted aspirin, 3 large duodenal lesions > 2 cm, and 2 early introduction of clopidogrel at day 1). The resection technique was endoscopic submucosal dissection (ESD) in 40 cases, en bloc endoscopic mucosal resection (EMR) in 16, piecemeal EMR in 6, and ampullectomy in 3. The mean lesion size was 37.9 mm (SD: 2.2 mm) with a mean area of 6.3 cm(2) (SD: 3.5 cm(2)). No difficulty was noted during application. Four delayed overt bleedings occurred (6.2 %) (3 hematochezia, 1 hematemesis) requiring endoscopic hemostasis. The mean hemoglobin drop off was 0.6 g/dL (- 0.6 to 3.1 g/dL). No adverse events occurred.

CONCLUSION

The use of this novel extracellular matrix scaffold may help to reduce post-endoscopic resection bleedings including in high risk situations. Its use is easy and safe but further comparative studies are warranted to completely evaluate its effectiveness.

A new device to expedite endoscopic submucosal dissection procedures: a randomized animal study of efficacy and safety (with videos)

BACKGROUND AND STUDY AIMS

Endoscopic submucosal dissection (ESD) is a recognized method for the curative treatment of superficial neoplasia, but its use is limited by lengthy procedures and the lack of versatility of existing knives. We developed a prototype ESD device with the ability to work as a needle, hook, or "scythe." This new device was compared to regular ESD knives in a randomized animal study.

PATIENTS AND METHODS

Eight pigs underwent two gastric ESD procedures each, similar in size and difficulty, one with a regular ESD device and the other with the new device. The order and location of each ESD, as well as the performing operator, were randomized. Primary judgment criterion was safety of procedures. Overall and submucosal dissection procedure times were measured. Time-to-surface ratios were measured and estimated for ESDs larger than those performed. Histopathology of the resected tissue and remaining stomach was done after each experiment.

RESULTS

No complications were observed throughout the study and all resections were completed en-bloc and uneventfully. The submucosal extension of resections was similar with both the standard and the new devices. A comparison of time-consumption between groups did not show statistically significant differences, but a dramatic reduction of procedure duration was observed in some procedures with the new device; based on observed data, a potential time-saving of up to 66 % was anticipated, with a relatively short learning curve.

CONCLUSIONS

This new versatile device proved to be as safe as regular ESD knives, and seems likely to help reduce the duration of the procedure.

Endoscopic submucosal dissection for early Barrett's neoplasia

INTRODUCTION

The possible benefit of endoscopic submucosal dissection (ESD) for early neoplasia arising in Barrett's esophagus remains controversial. We aimed to assess the efficacy and safety of ESD for the treatment of early Barrett's neoplasia.

METHODS

All consecutive patients undergoing ESD for the resection of a visible lesion in a Barrett's esophagus, either suspicious of submucosal infiltration or exceeding 10 mm in size, between February 2012 and January 2015 were prospectively included. The primary endpoint was the rate of curative resection of carcinoma, defined as histologically complete resection of adenocarcinomas without poor histoprognostic factors.

RESULTS

Thirty-five patients (36 lesions) with a mean age of 66.2 ± 12 years, a mean ASA score of 2.1 ± 0.7, and a mean C4M6 Barrett's segment were included. The mean procedure time was 191 ± 79 mn, and the mean size of the resected specimen was 51.3 ± 23 mm. En bloc resection rate was 89%. Lesions were 12 ± 15 mm in size, and 81% (29/36) were invasive adenocarcinomas, six of which with submucosal invasion. Although R0 resection of carcinoma was 72.4%, the curative resection rate was 66% (19/29). After a mean follow-up of 12.9 ± 9 months, 16 (45.7%) patients had required additional treatment, among whom nine underwent surgical resection, and seven further endoscopic treatments. Metachronous lesions or recurrence of cancer developed during the follow-up period in 17.2% of the patients. The overall complication rate was 16.7%, including 8.3% perforations, all conservatively managed, and no bleeding. The 30-day mortality was 0%.

CONCLUSION

In this early experience, ESD yielded a moderate curative resection rate in Barrett's neoplasia. At present, improvements are needed if ESD is to replace piecemeal endoscopic mucosal resection in the management of Barrett's neoplasia.

Emerging indications of endoscopic radiofrequency ablation

INTRODUCTION

Radiofrequency ablation (RFA) is a well-validated treatment of dysplastic Barrett's esophagus. Other indications of endoscopic RFA are under evaluation.

RESULTS

Four prospective studies (total 69 patients) have shown that RFA achieved complete remission of early esophageal squamous intra-epithelial neoplasia at a rate of 80%, but with a substantial risk of stricture. In the setting of gastric antral vascular ectasia, two prospective monocenter studies, and a retrospective multicenter study, (total 51 patients), suggest that RFA is efficacious in terms of reducing transfusion dependency. In the setting of chronic hemorrhagic radiation proctopathy, a prospective monocenter study and a retrospective multicenter study (total 56 patients) suggest that RFA is an efficient treatment. A retrospective comparative study (64 patients) suggests that RFA improves stents patency in malignant biliary strictures.

CONCLUSIONS

Endoscopic RFA is an upcoming treatment modality in early esophageal squamous intra-epithelial neoplasia, as well as in gastric, rectal, and biliary diseases.

Toward an easier indigocarmine chromoendoscopy

Indigocarmine chromoendoscopy has been proven to improve the detection of colonic lesions during screening colonoscopy, and is associated with increased adenoma detection rates. Furthermore, it is commonly used to help in the delineation and characterization of colorectal neoplasms. However, it usually requires the use of a spraying catheter that decreases the suction capacity of the endoscope, and is time- consuming. Herein, we report on the feasibility of indigo carmine chromoendoscopy during colonoscopy without using a spraying catheter, with the dye being administered through the air/water channel of the endoscope. Since the suction channel remains free, the air can be exsufflated and the staining then applies uniformly onto the colonic walls with the excess indigocarmine dye being immediately eliminated. In our experience with various types of colonoscopes and cap-assisted colonoscopy, this procedure makes indigocarmine chromoendoscopy much easier and quicker to perform, and might save the use of a spray catheter.