Endoscopic Shielding With Platelet-rich Plasma After Resection Of Large Colorectal Lesions.

BACKGROUND: Platelet-rich plasma (PRP) has demonstrated efficacy as submucosal injection before endoscopic mucosal resection or local injection after endoscopic submucosal dissection of nonpedunculated colorectal lesions. METHODS: The EndoPRP study was a prospective single-center study to analyze the efficacy of PRP shield after endoscopic mucosal resection of large nonpedunculated colorectal lesio with impossible clip closure, assessed by the incidence of delayed bleeding (DB) and delayed perforation, and percentage of mucosal restoration after 4 weeks (mucosal healing rate). RESULTS: Shielding technique with PRP was performed in 4 patients, aged 52 to 80, with 4 lesions at rectum (mean size 53.7±20.6 mm, range 35 to 80 mm). DB occurred in 1 lesion (25% of all lesions), no required blood transfusion or endoscopic treatment. No postoperative delayed perforation occurred. Mucosal healing rate was of 78.6% after 4 weeks. CONCLUSIONS: PRP shield failed in prevent DB, probably due to migration and failure in the adherence in large wounds. Future comparative studies are needed to confirm these data.

Comparative study of electrical and rheological properties of different solutions used in endoscopic mucosal resection.

BACKGROUND AND AIM: The study of electrical and rheological properties of solutions to carry out endoscopic resection procedures could determinate the best candidate. An ex vivo study with porcine stomachs was conducted to analyze electrical resistivity (R) and rheological properties (temperature, viscosity, height and lasting of the cushion) of different substances used in these techniques. METHODS: Tested solutions were: 0.9% saline (S), platelet-rich plasma (PRP), Gliceol (GC), hyaluronic acid 2% (HA), Pluronic-F127 20% (PL), saline with 10% glucose (GS), Gelaspan (GP), Covergel-BiBio (TB) and PRP with TB (PRP+TB). Measurements of electrical and rheological properties were done at 0, 15, 30, 45 and 60 min after submucosal injection. RESULTS: Solutions showed a wide variability of transepithelial R after submucosal injection. Substances able to maintain the highest R 60 min postinjection were TB (7 × 104 Ω), HA (7 × 104 Ω) and PL (7 × 104 Ω). Protective solutions against deep thermal injury (Tª lower than 60°C) were PL (47.6°C), TB (55°C) and HA (56.63°C). Shortest time to carry out resections were observed with GC (17.66″), PRP (20.3″) and GS (23.45″). Solutions with less cushion decrease (<25%) after 60 min were TB (11.74%), PL (18.63%) and PRP (22.12%). CONCLUSIONS: Covergel-BiBio, PL and HA were the best solutions with long-term protective effects (transepithelial R, lower thermal injury and less cushion decrease). Solutions with quicker resection time were GC, PRP and GS.

Endoscopic shielding technique, a new method in therapeutic endoscopy.

Prevention of late complications after large endoscopic resection is inefficient with current methods. Endoscopic shielding, as a simple and safe technique, has been proposed to improve the incidence of these events. Different methods, sheets or hydrogels, have showed proven efficacy in the prevention of late bleeding and perforation, as well as the improvement of tissue repair, in experimental models and in clinical practice.

Endoscopic shielding technique with a newly developed hydrogel to prevent thermal injury in two experimental models.

BACKGROUND AND AIM: A newly developed hydrogel, applied through the endoscope as an endoscopic shielding technique (EndoSTech), is aimed to prevent deep thermal injury and to accelerate the healing process of colonic induced ulcers after therapeutic endoscopy. METHODS: Lesions were performed in rats (n = 24) and pigs (n = 8). Rats were randomized to receive EndoSTech (eight rats each) with: saline (control), hyaluronic acid and product. In pigs, three ulcer sites were produced in each pig: endoscopic mucosal resection (EMR)-ulcer with prior saline injection (A; EMR-saline), EMR-saline plus EndoSTech with product (B; EMR-saline-P), and EMR with prior injection of product plus EndoSTech-P (C; EMR-P-P). At the end of the 14-day study, the same lesions were performed again in healthy mucosa to assess acute injury. Animals were sacrificed after 7 (rats) and 14 (pigs) days. Ulcers were macroscopically and histopathologically evaluated. Thermal injury (necrosis) was assessed with a 1-4 scale. RESULTS: In rats, treatment with product improved mucosal healing comparing with saline and hyaluronic acid (70% vs 30.3% and 47.2%; P = 0.003), avoiding mortality (0% vs 50% and 25%; P = 0.038), and perforation (0% vs 100% and 33.3%; P = 0.02); respectively. In pigs, submucosal injection of product induced a marked trend towards a less deep thermal injury (C = 2.25-0.46 vs A and B = 2.75-0.46; P = 0.127). Mucosal healing rate was higher with product (B = 90.2-3.9%, C = 91.3-5.5% vs A = 73.1-12.6%; P = 0.002). CONCLUSIONS: This new hydrogel demonstrates strong healing properties in preclinical models. In addition, submucosal injection of this product is able to avoid high thermal load of the gastrointestinal wall.

New method for isolation of rat lamina propria macrophages in colonic tissue.

Studies on intestinal cells in the lamina propria are important for understanding the cellular and immune responses in the gut. There is a lack of specific isolating procedures of macrophage cells in rats. Two different procedures of macrophage isolation of the lamina propria in rats are compared: a standard mice protocol for lymphocyte isolation (A) adapted to rat samples and a new protocol developed specifically for rats (B). Significant differences are observed when analyzing the effect of the isolation method on the cell number, viability and phenotype. This has important implications when further functional studies are required.

Microperforation of the colon: animal model in rats to reproduce mucosal thermal damage.

BACKGROUND: The aim of the present study was to develop a rat model of colonic microperforation secondary to thermal injury for future studies to assess new treatments. METHODS: Twenty-four male Sprague-Dawley rats were used in this study. Hot biopsy forceps were used for all treatments. All lesions were created in proximal left colon using the soft coagulation setting. The power setting tested was 40 W, and the durations of monopolar soft coagulation application evaluated were 2, 3, and 4 s. RESULTS: In the acute phase, 48 h after thermal injury, durations of cautery of 2 and 3 s resulted in transmural necrosis, whereas with 4 s microperforation was obtained. In the late phase, 7 d after the damage, only duration of cautery of 4 s showed deep cautery effects, with signs of peritonitis. CONCLUSIONS: We determined optimal power settings and duration of therapy in a rat model for producing electrocautery that involves transmural necrosis with microperforation.

Colonoscopy in rats: An endoscopic, histological and tomographic study.

AIM: To describe colon anatomy with colonoscopy and computed tomography (CT) to develop a rat model for future studies of therapeutic colonoscopy. METHODS: Eighteen male Sprague-Dawley rats, on average 400-420 g, underwent total colonoscopy, CT and histological examination. Colonoscopy was performed after bowel preparation with a baby upper gastrointestinal endoscopy with an outer diameter of 6.7 mm. CT obtained a 3D image of total colon after a rectal enema with radiological contrast. Macroscopic and microscopic examinations were examined with a conventional technique (hematoxylin and eosin). Colonic wall thickness, length and diameter measurements were taken from the anus, 3, 7, 14 and 20 cm from the anal margin. RESULTS: The median colonoscope depth was 24 cm (range 20-28 cm). Endoscopic and tomographic study of colon morphology showed an easy access with tubular morphology in the entire left colon (proximal left colon and rectum). Transverse colon was unapparent on colonoscopy. Right colon, proximal to the splenic flexure, was the largest part of the colon and assumed saccular morphology with tangential trabecula. Radiological measurements of the colonic length and diameter substantiate a subdivision of the right colon into two parts, the cecum and distal right colon. In addition, histological measurement of the colonic wall thickness confirmed a progressive decrease from rectum to cecum. The muscular layer was thinner in the proximal left colon. CONCLUSION: The combination of colonoscopy, tomography and histology leads to a better characterization of the entire colon. These data are important for deciding when to perform endoscopic resections or when to induce perforations to apply endoscopic treatments.

Role of scavenger receptors in the pathophysiology of chronic liver diseases.

Scavenger receptors comprise a large family of structurally diverse proteins that are involved in many homeostatic functions. They recognize a wide range of ligands, from pathogen-associated molecular patterns (PAMPs) to endogenous, as well as modified host-derived molecules (DAMPs). The liver deals with blood micro-organisms and DAMPs released from injured organs, thus performing vital metabolic and clearance functions that require the uptake of nutrients and toxins. Many liver cell types, including hepatocytes and Kupffer cells, express scavenger receptors that play key roles in hepatitis C virus entry, lipid uptake, and macrophage activation, among others. Chronic liver disease causes high morbidity and mortality worldwide. Hepatitis virus infection, alcohol abuse, and non-alcoholic fatty liver are the main etiologies associated with this disease. In this context, continuous inflammation as a result of liver damage leads to hepatic fibrosis, which frequently brings about cirrhosis and ultimately hepatocellular carcinoma. In this review, we will summarize the role of scavenger receptors in the pathophysiology of chronic liver diseases. We will also emphasize their potential as biomarkers of advanced liver disease, including cirrhosis and cancer.

Determination of the ideal preparation for colonoscopy in a rat model.

BACKGROUND: Quality bowel preparation is essential to examine the entire colon adequately. No trials comparing different purgative regimens are available in animal models. The aim was to compare 5 methods for bowel cleansing to develop a rat model to study therapeutic colonoscopy. METHODS: Twenty-five rats were assigned to one of 5 regimens: (1) high-volume polyethylene glycol electrolyte solution (HV-PEG-ES, 40 mL); (2) low-volume PEG-ES (LV-PEG-ES, 20 mL); (3) high-volume PEG-ES+ascorbic acid (HV-PEG-ES+AA, 20 mL); (4) LV-PEG-ES+AA, 10 mL; (5) rectal enema with saline solution (RE-SS). Bowel preparation quality was rated by total colonoscopy. RESULTS: RE-SS is the best regime for left colon cleansing, whereas HV-PEG-ES and HV-PEG-ES+AA solutions resulted in significantly better cleansing in the whole colon. HV-PEG-ES+AA regimen needed less volume, and administration was easier. CONCLUSIONS: A total of 20 mL of PEG-ES+AA before colonoscopy is the best regimen to explore the whole colon, whereas to explore the left colon RE-SS is adequate.

Serum concentrations of insulin-like growth factor-I (igf-I) as a marker of liver fibrosis in patients with chronic hepatitis C.

Liver biopsy was until recently the only way of evaluating liver fibrosis. Noninvasive tests for hepatic fibrosis, without potential risks, are desired by clinicians as well as patients. Insulin-like growth factor-I (IGF-I) synthesis is disturbed in liver fibrosis and reflects the severity of the clinical stage. We assessed serum IGF-I levels in patients with chronic hepatitis C (CHC) to correlate with liver fibrosis and antiviral therapy. Forty patients with CHC and persistently abnormal alanine aminotransferase values were enrolled and treated with peginterferon alpha-2a 180 microg per week plus ribavirin for 24 (n=20) or 48 (n=20) weeks. All patients underwent liver biopsy before treatment (METAVIR fibrosis stage F0, n=13; F1-F2, n=14; F3, n=7; F4, n=6). Serum IGF-I was measured at baseline, at the end of treatment period, and 24 weeks after finishing treatment. Mean IGF-I values were significantly lower in patients with advanced fibrosis (F4, 65.9+/-17.9 ng/mL) than in the others (F0, 145.2+/-47.1; F1-F2, 150.3+/-89.6; and F3, 121.4+/-35.2 ng/mL; P < .05). Serum IGF-I levels increased during combined therapy, being this increment markedly higher in patients with sustained virologic response. In conclusion, IGF-I synthesis is disturbed in CHC and reflects the severity of the liver fibrosis. Combined therapy improves serum IGF-I levels. IGF-I could represent a good, noninvasive marker of liver fibrosis.

Functional abnormalities of the motor tract in the rat after portocaval anastomosis and after carbon tetrachloride induction of cirrhosis.

INTRODUCTION: Hepatic encephalopathy is a neurologic syndrome secondary to liver failure that causes cognitive and motor abnormalities. Impairment in the function of the first neuron of the motor tract (corticospinal tract) has been demonstrated in patients with cirrhosis and minimal hepatic encephalopathy. AIM: Investigate the function of the first neuron of the motor tract in experimental models of minimal hepatic encephalopathy. MATERIAL AND METHODS: Rats with portocaval anastomosis (n = 8) and rats with carbon tetrachloride induced cirrhosis (n = 11) underwent neurophysiological recording under light anesthesia with propofol. Motor evoked potentials were elicited applying a transcranial electric pulse and were recorded in the tibialis anterior muscle. The effect of the dose of anesthesia was assessed in a group of normal rats (n = 10). RESULTS: Rats with portocaval anastomosis exhibited a decrease in motor evoked potentials amplitude following surgery (67 +/- 11 to 41 +/- 16%, P < 0.001). Cirrhotic rats exhibited an increase in motor evoked potentials latency after the appearance of ascites (4.65 +/- 0.43 to 5.15 +/- 0.67 ms., P = 0.04). Increasing doses of propofol produced a decrease in the amplitude and an increase in the latency of motor evoked potentials. CONCLUSION: It is possible to reproduce functional abnormalities of the central motor tract in rats with portocaval anastomosis and carbon tetrachloride induced cirrhosis. The development of motor abnormalities in experimental models of minimal hepatic encephalopathy offers the possibility to investigate the mechanisms involved in the pathogenesis of hepatic encephalopathy and test therapeutic strategies.