Detection of Intestinal Tissue Perfusion by Real-Time Breath Methane Analysis in Rat and Pig Models of Mesenteric Circulatory Distress.

OBJECTIVES: Methane (CH4) breath test is an established diagnostic method for gastrointestinal functional disorders. Our aim was to explore the possible link between splanchnic circulatory changes and exhaled CH4 in an attempt to recognize intestinal perfusion failure. DESIGN: Randomized, controlled in vivo animal study. SETTING: University research laboratory. SUBJECTS: Anesthetized, ventilated Sprague-Dawley rats (280 ± 30 g) and Vietnamese minipigs (31 ± 7 kg). INTERVENTIONS: In the first series, CH4 was administered intraluminally into the ileum before 45 minutes mesenteric ischemia or before reperfusion in non-CH4 producer rats to test the appearance of the gas in the exhaled air. In the porcine experiments, the superior mesenteric artery was gradually obstructed during consecutive, 30-minute flow reductions and 30-minute reperfusions achieving complete occlusion after four cycles (n = 6), or nonocclusive mesenteric ischemia was induced by pericardial tamponade (n = 12), which decreased superior mesenteric artery flow from 351 ± 55 to 182 ± 67 mL/min and mean arterial pressure from 96.7 ± 18.2 to 41.5 ± 4.6 mm Hg for 60 minutes. MEASUREMENTS AND MAIN RESULTS: Macrohemodynamics were monitored continuously; RBC velocity of the ileal serosa or mucosa was recorded by intravital videomicroscopy. The concentration of exhaled CH4 was measured online simultaneously with high-sensitivity photoacoustic spectroscopy. The intestinal flow changes during the occlusion-reperfusion phases were accompanied by parallel changes in breath CH4 output. Also in cardiac tamponade-induced nonocclusive intestinal ischemia, the superior mesenteric artery flow and RBC velocity correlated significantly with parallel changes in CH4 concentration in the exhaled air (Pearson's r = 0.669 or r = 0.632, respectively). CONCLUSIONS: we report a combination of in vivo experimental data on a close association of an exhaled endogenous gas with acute mesenteric macro- and microvascular flow changes. Breath CH4 analysis may offer a noninvasive approach to follow the status of the splanchnic circulation.

Acetylsalicylic acid-tris-hydroxymethyl-aminomethane reduces colon mucosal damage without causing gastric side effects in a rat model of colitis.

BACKGROUND: We have developed a novel compound from acetylsalicylic acid (ASA) and 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris) precursors with ASA-like anti-inflammatory efficacy and reduced the mucosa-damaging side-effects. Our aim was to examine local and remote consequences of ASA-Tris administration in 2-,4-,6-trinitrobenzene-sulfonic acid (TNBS)-induced colitis as compared to ASA or mesalamine (5-aminosalicylate) treatment. METHODS: Sprague-Dawley rats were randomized to five groups (n = 6, each), and TNBS enemas were performed. Group 1 was the negative control; group 2 was the untreated colitis group. 12 hour after colitis induction repeated doses of ASA, ASA-Tris (both 0.55 mmol/kg) and mesalamine (0.77 mmol/kg) were given 3 times daily for 3 days to groups 3-5. On day 3 of colitis, the in vivo histology of the colon and stomach was investigated. Tissue xanthine-oxidoreductase, myeloperoxidase, nitrite/nitrate changes, and circulating TNF-alpha levels were measured. In addition, liver mitochondria were examined with high-resolution respirometry to analyze alterations in the electron transport chain. RESULTS: TNBS enema significantly elevated inflammatory enzyme activities, NO production, TNF-alpha concentration, and induced morphological damage in the colon. ASA-treatment reduced the inflammatory marker levels and mucosal injury in the colon, but gastric tissue damage was present. ASA-Tris- and mesalamine-treatments significantly reduced the cytokine levels, inflammatory enzyme activities, and colonic mucosal damage without inducing gastric injury. Also, ASA significantly reduced the Complex IV-linked respiration of liver mitochondria, which was not observed after ASA-Tris-treatment. CONCLUSION: As compared to ASA, ASA-Tris conjugation provides significant protection against the colonic injury and cytokine-mediated progression of inflammatory events in experimental colitis without influencing the gastric epithelial structure.

[Experimental model for cardiogenic shock with pericardial tamponade]. / A cardiogen sokk modellezése pericardialis tamponáddal.

INTRODUCTION: Pericardial tamponade (PT) is a life-threatening condition, with low cardiac output. The hemodynamic consequences of PT can severely affect the circulation of all tissues, including the microcirculation of the kidneys and the intestinal mucosa. Our aim was to develop a hemodynamically stable and controllable large animal model of PT to study the consequences of cardiogenic shock. METHODS: Two groups of anesthetized vietnamese minipigs (n = 6, both groups) were used. Following laparotomy, a cannula was fixed into the pericardium through the diaphragm without thoracotomy. A sham-operated group served as control, in the second group 60-min PT was induced by intrapericardial injection of heparinised own blood. Throughout PT and 180-min reperfusion, macrohemodynamics, renal circulation and mesenteric macro- and microcirculation were monitored. Myeloperoxidase (MPO) activity was measured and in vivo histology was performed by confocal laser scanning endomicroscopy. RESULTS: The PT increased central venous pressure, heart rate and decreased mean arterial pressure, mesenteric flow (from 355.5 ± 112.4 vs 182.0 ± 59.1 ml/min) and renal arterial flow (from 159.63 ± 50.7 vs 35.902 ± 27.9 ml/min) and the microcirculation of the ileum. Elevated MPO activity (3.66 ± 1.6 vs 7.01 ± 1.44 mU/mg protein) and injury of the ileal mucosa were present also. SUMMARY: The reproducible large animal model is suitable for clinically relevant investigations of the hemodynamic and biochemical consequences of PT.

Conjugation with Tris Decreases the Risk of Ketoprofen-Induced Mucosal Damage and Reduces Inflammation-Associated Methane Production in a Rat Model of Colitis.

We have designed a new compound from the non-steroidal anti-inflammatory drug (NSAID) ketoprofen (Ket) and 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris) precursors, with the aim to reduce the gastrointestinal (GI) side effects of NSAID therapies. We investigated mucosal reactions in a standard rat model of colitis together with methane generation as a possible indicator of pro-inflammatory activation under this condition (approval number: V./148/2013). Whole-body methane production (photoacoustic spectroscopy) and serosal microcirculation (intravital videomicroscopy) were measured, and mucosal damage was assessed (conventional histology; in vivo laser-scanning endomicroscopy). Inflammatory markers were measured from tissue and blood samples. Colitis induced an inflammatory response, morphological colonic damage and increased methane output. Ket treatment lowered inflammatory activation and colonic mucosal injury, but macroscopic gastric bleeding and increased methane output were present. Ket-Tris reduced inflammatory activation, methane emission and colonic mucosal damage, without inducing gastric injury. Conjugation with Tris reduces the GI side effects of Ket and still decreases the inflammatory response in experimental colitis. Methane output correlates with the mucosal inflammatory response and non-invasively demonstrates the effects of anti-inflammatory treatments.

Reduced mucosal side-effects of acetylsalicylic acid after conjugation with tris-hydroxymethyl-aminomethane. Synthesis and biological evaluation of a new anti-inflammatory compound.

Acetylsalicylic acid (ASA) causes adverse haemorrhagic reactions in the upper gastrointestinal (GI) tract, and previous results have suggested that combination therapy with 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris) could provide protection in this scenario. Based on this hypothesis, our aim was to develop a new compound from ASA and Tris precursors and to characterize the biological effects of ASA-Tris and the derivatives ASA-bis- and mono-hydroxymethyl-aminomethane (ASA-Bis, ASA-Mono, respectively) using in vivo and in vitro test systems. ASA or ASA conjugates (0.55mmol/kg, each) were administered intragastrically to Sprague-Dawley rats. Changes in the mucosal structure and in the serosal microcirculation were detected by in vivo imaging techniques, the plasma TNF-alpha, tissue xanthine oxidoreductase and myeloperoxidase activities, and liver cytochrome c changes were also determined. In two separate series, platelet aggregation and carrageenan arthritis-induced inflammatory pain were measured in control, ASA and ASA-Tris-treated groups. Severe mucosal injury and a significant decrease in serosal red blood cell velocity developed in the ASA-treated group and an ~2-fold elevation in proinflammatory mediator levels evolved. ASA-Tris did not cause bleeding, microcirculatory dysfunction, mucosal injury or an elevation in proinflammatory markers. The ASA-Mono and ASA-Bis conjugates did not cause macroscopic bleeding, but the inflammatory activation was apparent. ASA-Tris did not influence the cyclooxygenase-induced platelet aggregation significantly, but the inflammatory pain was reduced as effectively as in the case of equimolar ASA doses. ASA-Tris conjugation is an effective approach through which the GI side-effects of ASA are controlled by decreasing the cytokine-mediated progression of pro-inflammatory events.