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.

Veno-Venous Extracorporeal Membrane Oxygenation in Minipigs as a Robust Tool to Model Acute Kidney Injury: Technical Notes and Characteristics.

Objective: Veno-venous extracorporeal membrane oxygenation (vv-ECMO) can save lives in severe respiratory distress, but this innovative approach has serious side-effects and is accompanied by higher rates of iatrogenic morbidity. Our aims were, first, to establish a large animal model of vv-ECMO to study the pathomechanism of complications within a clinically relevant time frame and, second, to investigate renal reactions to increase the likelihood of identifying novel targets and to improve clinical outcomes of vv-ECMO-induced acute kidney injury (AKI). Methods: Anesthetized Vietnamese miniature pigs were used. After cannulation of the right jugular and femoral veins, vv-ECMO was started and maintained for 24 hrs. In Group 1 (n = 6) ECMO was followed by a further 6-hr post-ECMO period, while (n = 6) cannulation was performed without ECMO in the control group, with observation maintained for 30 h. Systemic hemodynamics, blood gas values and hour diuresis were monitored. Renal artery flow (RAF) was measured in the post-ECMO period with an ultrasonic flowmeter. At the end of the experiments, renal tissue samples were taken for histology to measure myeloperoxidase (MPO) and xanthine oxidoreductase (XOR) activity and to examine mitochondrial function with high-resolution respirometry (HRR, Oroboros, Austria). Plasma and urine samples were collected every 6 hrs to determine neutrophil gelatinase-associated lipocalin (NGAL) concentrations. Results: During the post-ECMO period, RAF dropped (96.3 ± 21 vs. 223.6 ± 32 ml/min) and, similarly, hour diuresis was significantly lower as compared to the control group (3.25 ± 0.4 ml/h/kg vs. 4.83 ± 0.6 ml/h/kg). Renal histology demonstrated significant structural damage characteristic of ischemic injury in the tubular system. In the vv-ECMO group NGAL levels, rose significantly in both urine (4.24 ± 0.25 vs. 2.57 ± 0.26 ng/ml) and plasma samples (4.67 ± 0.1 vs. 3.22 ± 0.2 ng/ml), while tissue XOR (5.88 ± 0.8 vs. 2.57 ± 0.2 pmol/min/mg protein) and MPO (11.93 ± 2.5 vs. 4.34 ± 0.6 mU/mg protein) activity was elevated. HRR showed renal mitochondrial dysfunction, including a significant drop in complex-I-dependent oxidative capacity (174.93 ± 12.7 vs. 249 ± 30.07 pmol/s/ml). Conclusion: Significantly decreased renal function with signs of structural damage and impaired mitochondrial function developed in the vv-ECMO group. The vv-ECMO-induced acute renal impairment in this 30-hr research protocol provides a good basis to study the pathomechanism, biomarker combinations or possible therapeutic possibilities for AKI.

Prolonged ischemia of the ileum and colon after surgical mucosectomy explains contraction and failure of "mucus free" bladder augmentation.

INTRODUCTION: Mucus production by the intestinal segment used in bladder augmentation results in long term concerns especially stones and UTI. Bladder augmentation with demucosalized intestinal flap is a potential promising approach for mucus-free bladder augmentation, however the contraction of the flap remains a major concern. Mucosectomy has been shown to result in abrupt and immediate cessation of microcirculation in the ileum. However, assessment of microcirculation shortly after mucosectomy may miss a gradual recovery of micro-circulation over a longer period of time. Previous studies have not assessed the colon response to mucosectomy. OBJECTIVE: Our aim was to assess the effect of mucosectomy on the microcirculation of the colon and ileum beyond the known warm ischemia time. STUDY DESIGN: Ileum and colon segments were detubularised and mucosectomy was performed in (n = 8) anesthetised minipigs. Group A: sero-musculo-submucosal flaps were created with removal of the mucosa and preserving the submucosal layer Group B: sero-muscular flaps were created with the removal of submucosal-mucosal layer. The Microvascular Flow Index (MFI), the velocity of the circulating red blood cells (RBCV) was measured using Intravital Dark Field (IDF) side stream videomicroscopy (Cytoscan Braedius, The Netherlands) after mucosectomy, for up to 180 min. RESULTS: Both the MFI and RBCV showed an abrupt reduction of microcirculation, on both surfaces of the remaining intestinal flap, in the ileum as well as in the colon. Slightly better values were seen in Group A of the colon, but even these values remain far below the preoperative (control) results. Some, tendency of recovery of the microcirculation was noted after 60-90 min, but this remained significantly lower than the preoperative control values at 180 min. CONCLUSION: Both the ileal and the colonic flap remains in severe ischemia after mucosectomy beyond the warm ischemia time. DISCUSSION: This study shows that surgical mucosectomy compromises vascular integrity of the intestinal flaps used for bladder augmentation. Partial recovery which occurs within the warm ischemia time is not significant enough to avoid fibrosis therefore flap shrinkage may be inevitable with this technique. LIMITATION: The gastrointestinal structure of the porcine model is not the same exactly as the human gastrointestinal system. However, although not an exact match it is the closest, readily available animal model to the human gastrointestinal system.

A Porcine Sepsis Model With Numerical Scoring for Early Prediction of Severity.

Introduction: Sepsis can lead to organ dysfunctions with disturbed oxygen dynamics and life-threatening consequences. Since the results of organ-protective treatments cannot always be transferred from laboratory models into human therapies, increasing the translational potential of preclinical settings is an important goal. Our aim was to develop a standardized research protocol, where the progression of sepsis-related events can be characterized reproducibly in model experiments within clinically-relevant time frames. Methods: Peritonitis was induced in anesthetized minipigs injected intraperitoneally with autofeces inoculum (n = 27) or with saline (sham operation; n = 9). The microbial colony-forming units (CFUs) in the inoculum were retrospectively determined. After awakening, clinically relevant supportive therapies were conducted. Nineteen inoculated animals developed sepsis without a fulminant reaction. Sixteen hours later, these animals were re-anesthetized for invasive monitoring. Blood samples were taken to detect plasma TNF-α, IL-10, big endothelin (bET), high mobility group box protein1 (HMGB1) levels and blood gases, and sublingual microcirculatory measurements were conducted. Hemodynamic, respiratory, coagulation, liver and kidney dysfunctions were detected to characterize the septic status with a pig-specific Sequential Organ Failure Assessment (pSOFA) score and its simplified version (respiratory, cardiovascular and renal failure) between 16 and 24 h of the experiments. Results: Despite the standardized sepsis induction, the animals could be clustered into two distinct levels of severity: a sepsis (n = 10; median pSOFA score = 2) and a septic shock (n = 9; median pSOFA score = 8) subgroup at 18 h of the experiments, when the decreased systemic vascular resistance, increased DO2 and VO2, and markedly increased ExO2 demonstrated a compensated hyperdynamic state. Septic animals showed severity-dependent scores for organ failure with reduced microcirculation despite the adequate oxygen dynamics. Sepsis severity characterized later with pSOFA scores was in correlation with the germ count in the induction inoculum (r = 0.664) and CFUs in hemocultures (r = 0.876). Early changes in plasma levels of TNF-α, bET and HMGB1 were all related to the late-onset organ dysfunctions characterized by pSOFA scores. Conclusions: This microbiologically-monitored, large animal model of intraabdominal sepsis is suitable for clinically-relevant investigations. The methodology combines the advantages of conscious and anesthetized studies, and mimics human sepsis and septic shock closely with the possibility of numerical quantification of host responses.

Bladder augmentation from an insider's perspective: a review of the literature on microcirculatory studies.

Augmentation cystoplasty is an exemplary multiorgan intervention in urology which is particularly associated with microvascular damage. Our aim was to review the available intravital imaging techniques and data obtained from clinical and experimental microcirculatory studies involving the most important donor organs applied in bladder augmentation. Although numerous direct or indirect methods are available to assess the condition of microvessels the implementation of microcirculatory diagnostic methods in humans is still challenging and the assessment of organ microcirculation in the operating theatre has limitations. Nevertheless, preclinical studies generally report good internal validity and although prospective human protocols with reduced variability are needed, a possible positive impact of microcirculatory diagnostics on the clinical outcomes of urologic surgery can be anticipated.

Reduction in hypoxia-reoxygenation-induced myocardial mitochondrial damage with exogenous methane.

Albeit previous experiments suggest potential anti-inflammatory effect of exogenous methane (CH4 ) in various organs, the mechanism of its bioactivity is not entirely understood. We aimed to investigate the potential mitochondrial effects and the underlying mechanisms of CH4 in rat cardiomyocytes and mitochondria under simulated ischaemia/reperfusion (sI/R) conditions. Three-day-old cultured cardiomyocytes were treated with 2.2% CH4 -artificial air mixture during 2-hour-long reoxygenation following 4-hour-long anoxia (sI/R and sI/R + CH4 , n = 6-6), with normoxic groups serving as controls (SH and SH + CH4 ; n = 6-6). Mitochondrial functions were investigated with high-resolution respirometry, and mitochondrial membrane injury was detected by cytochrome c release and apoptotic characteristics by using TUNEL staining. CH4 admixture had no effect on complex II (CII)-linked respiration under normoxia but significantly decreased the complex I (CI)-linked oxygen consumption. Nevertheless, addition of CH4 in the sI/R + CH4 group significantly reduced the respiratory activity of CII in contrast to CI and the CH4 treatment diminished mitochondrial H2 O2 production. Substrate-induced changes to membrane potential were partially preserved by CH4 , and additionally, cytochrome c release and apoptosis of cardiomyocytes were reduced in the CH4 -treated group. In conclusion, the addition of CH4 decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury in vitro.

Bioactivity of Inhaled Methane and Interactions With Other Biological Gases.

A number of studies have demonstrated explicit bioactivity for exogenous methane (CH4), even though it is conventionally considered as physiologically inert. Other reports cited in this review have demonstrated that inhaled, normoxic air-CH4 mixtures can modulate the in vivo pathways involved in oxidative and nitrosative stress responses and key events of mitochondrial respiration and apoptosis. The overview is divided into two parts, the first being devoted to a brief review of the effects of biologically important gases in the context of hypoxia, while the second part deals with CH4 bioactivity. Finally, the consequence of exogenous, normoxic CH4 administration is discussed under experimental hypoxia- or ischaemia-linked conditions and in interactions between CH4 and other biological gases, with a special emphasis on its versatile effects demonstrated in pulmonary pathologies.

Methane Exhalation Can Monitor the Microcirculatory Changes of the Intestinal Mucosa in a Large Animal Model of Hemorrhage and Fluid Resuscitation.

Background: Internal hemorrhage is a medical emergency, which requires immediate causal therapy, but the recognition may be difficult. The reactive changes of the mesenteric circulation may be part of the earliest hemodynamic responses to bleeding. Methane is present in the luminal atmosphere; thus, we hypothesized that it can track the intestinal circulatory changes, induced by hemorrhage, non-invasively. Our goal was to validate and compare the sensitivity of this method with an established technique using sublingual microcirculatory monitoring in a large animal model of controlled, graded hemorrhage and the early phase of following fluid resuscitation. Materials and Methods: The experiments were performed on anesthetized, ventilated Vietnamese minipigs (approval number: V/148/2013; n = 6). The animals were gradually bled seven times consecutively of 5% of their estimated blood volume (BV) each, followed by gradual fluid resuscitation with colloid (hydroxyethyl starch; 5% of the estimated BV/dose) until 80 mmHg mean arterial pressure was achieved. After each step, macrohemodynamic parameters were recorded, and exhaled methane level was monitored continuously with a custom-built photoacoustic laser-spectroscopy unit. The microcirculation of the sublingual area, ileal serosa, and mucosa was examined by intravital videomicroscopy (Cytocam-IDF, Braedius). Results: Mesenteric perfusion was significantly reduced by a 5% blood loss, whereas microperfusion in the oral cavity deteriorated after a 25% loss. A statistically significant correlation was found between exhaled methane levels, superior mesenteric artery flow (r = 0.93), or microcirculatory changes in the ileal serosa (ρ = 0.78) and mucosa (r = 0.77). After resuscitation, the ileal mucosal microcirculation increased rapidly [De Backer score (DBS): 2.36 ± 0.42 vs. 8.6 ± 2.1 mm-1], whereas serosal perfusion changed gradually and with a lower amplitude (DBS: 2.51 ± 0.48 vs. 5.73 ± 0.75). Sublingual perfusion correlated with mucosal (r = 0.74) and serosal (r = 0.66) mesenteric microperfusion during the hemorrhage phase but not during the resuscitation phase. Conclusion: Detection of exhaled methane levels is of diagnostic significance during experimental hemorrhage as it indicates blood loss earlier than sublingual microcirculatory changes and in the early phase of fluid resuscitation, the exhaled methane values change in association with the mesenteric perfusion and the microcirculation of the ileum.

Mucosectomy disrupting the enteric nervous system causes contraction and shrinkage of gastrointestinal flaps: potential implications for augmentation cystoplasty.

INTRODUCTION: Augmenting the bladder with a seromuscular gastrointestinal flap is a promising alternative approach aiming for a mucus-free bladder augmentation; however, the contraction (shrinkage) of the flaps remains a major concern. Enteric nervous system (ENS) abnormalities cause a failure of relaxation of the intestinal muscle layers in motility disorders such as Hirschsprung's disease and intestinal neuronal dysplasia. In mammals, the submucosal enteric nervous plexus contains nitrergic inhibitory motor neurons responsible for muscle relaxation. The authors hypothesize that mucosectomy disconnects the submucosal nervous plexus from the myenteric plexus resulting in flap shrinkage. STUDY DESIGN: After ethical approval, mucosectomy was performed on vascularized flaps from the ileum, colon, and stomach in five anesthetized pigs. In Group (I), only the mucosa was scraped off with forceps, creating a sero-musculo-submucosal flap, while in Group (II), the mucosa and submucosa were peeled off as one layer, leaving a seromuscular flap. Isolated and detubularized segments served as control. The width of each flap was measured before and after the mucosectomy. The ENS was assessed by neurofilament immunohistochemistry in conventional sections and by acetylcholinesterase and NADPH-diaphorase enzyme histochemistry in whole-mount preparations. RESULTS: The stomach contracted to a lesser extent of its original width, 92.82 ± 7.86% in Group (I) and 82.24 ± 6.96% in Group (II). The ileum contracted to 81.68 ± 4.25% in Group (I) and to 72.675 ± 5.36% in Group (II). The shrinkage was most noticeable in the colon: 83.89 ± 15.73% in Group (I) and to 57.13 ± 11.51% in Group (II). One-way equal variance test showed significant difference (P < 0,05) between Group (I) and (II), comparing stomach with ileum and ileum with colon. The histochemistry revealed that the submucosal nervous plexus containing nitrergic inhibitory neurons was disconnected from the myenteric plexus in Group (II) of all specimens. CONCLUSION: Mucosectomy resulted in significant immediate shrinkage of the flaps. This was more expressed when also the submucosa was peeled off, thus fully disrupting the ENS. The shrinkage affected the stomach the least and the colon the greatest. This phenomenon should be taken into consideration when planning mucus-free bladder augmentation.

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.

Methane inhalation reduces the systemic inflammatory response in a large animal model of extracorporeal circulation.

OBJECTIVES: Extracorporeal circulation induces cellular and humoral inflammatory reactions, thus possibly leading to detrimental secondary inflammatory responses. Previous data have demonstrated the bioactive potential of methane and confirmed its anti-inflammatory effects in model experiments. Our goal was to investigate the in vivo consequences of exogenous methane administration on extracorporeal circulation-induced inflammation. METHODS: Two groups of anaesthetized Vietnamese minipigs (non-treated and methane treated, n = 5 each) were included. Standard central cannulation was performed, and extracorporeal circulation was maintained for 120 min without cardiac arrest or ischaemia, followed by an additional 120-min observation period with haemodynamic monitoring. In the methane-treated group, 2.5% v/v methane-normoxic air mixture was added to the oxygenator sweep gas. Blood samples through the central venous line and tissue biopsies from the heart, ileum and kidney were taken at the end point to determine the whole blood superoxide production (chemiluminometry) and the activity of xanthine-oxidoreductase and myeloperoxidase, with substrate-specific reactions. RESULTS: Methane treatment resulted in significantly higher renal blood flow during the extracorporeal circulation period compared to the non-treated group (63.9 ± 16.4 vs 29.0 ± 9.3 ml/min). Whole blood superoxide production (548 ± 179 vs 1283 ± 193 Relative Light Unit (RLU)), ileal myeloperoxidase (2.23 ± 0.2 vs 3.26 ± 0.6 mU/(mg protein)) and cardiac (1.5 ± 0.6 vs 4.7 ± 2.5 pmol/min/mg), ileal (2.2 ± 0.6 vs 7.0 ± 3.4 pmol/min/mg) and renal (1.2 ± 0.8 vs 13.3 ± 8.0 pmol/min/mg) xanthine-oxidoreductase activity were significantly lower in the treated group. CONCLUSIONS: The addition of bioactive gases, such as methane, through the oxygenator of the extracorporeal circuit represents a novel strategy to influence the inflammatory effects of extracorporeal perfusion in cardiac surgical procedures.

Experimental pericardial tamponade-translation of a clinical problem to its large animal model.

OBJECTIVES: Pericardial tamponade is a life-threatening medical emergency, when the hemodynamic consequences of low cardiac output severely disturb the perfusion of the peripheral tissues. Our aim was to design a reliable large animal model to reproduce the clinical scenario with the relevant pathophysiological consequences of pericardial tamponade -induced cardiogenic shock. MATERIAL AND METHODS: Anesthetized Vietnamese mini pigs were used (n=12). Following laparotomy, a cannula was fixed into the pericardium through the diaphragm without thoracotomy. A sham-operated group (n=6) served as control, while in the second group (n=6) pericardial tamponade was induced by intra-pericardial injection of heparinized own blood. Throughout the 60-min pericardial tamponade and the 180-min reperfusion, macro hemodynamics, renal circulation and the mesenteric macro- and micro-circulatory parameters were monitored. Myeloperoxidase activity was measured to detect neutrophil leukocyte accumulation and in vivo histology was performed by confocal laser scanning endomicroscopy to observe the structural changes of the intestinal mucosa. RESULTS: PT increased the central venous pressure, heart rate, and decreased mean arterial pressure. The mesenteric artery 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 micro-circulation of the ileum was reduced. The myeloperoxidase activity was elevated (from 3.66±1.6 to 7.01±1.44 mU/mg protein) and manifest injury of the ileal mucosa was present. CONCLUSION: This experimental model suitably mimics the hemodynamics and the pathology of clinical pericardial tamponade situations, and on this basis, it provides an opportunity to study the adverse macro- and micro-circulatory effects and biochemical consequences of human cardiogenic shock.

Mean arterial pressure targeted fluid resuscitation may lead to fluid overload: A bleeding-resuscitation animal experiment.

INTRODUCTION: Fluid resuscitation is the cornerstone of treatment in hemorrhagic shock. Despite increasing doubts, several guidelines recommend to maintain mean arterial pressure (MAP) >65 mmHg as the most frequent indication of fluid therapy. Our aim was to investigate the effects of a MAP-guided management in a bleeding-resuscitation animal experiment. MATERIALS AND METHODS: After anesthesia and instrumentation (tbsl) animals were bled till the initial stroke volume index dropped by 50% (t0). Fluid replacement was performed in 4 equivalent steps (t1-4) with balanced crystalloid solution to reach the baseline values of MAP. Invasive hemodynamic measurements and blood gas analyses were performed after each step. RESULTS: Mean arterial pressure dropped from tbsl to t0 (114±11 vs 76.9±16.9 mmHg, p<0.001) and returned to baseline by t4 (101.4±14.4 mmHg). From tbsl-t0 stroke volume index (SVI), cardiac index (CI) decreased (SVI: 40±8.6 vs 19.3±3.6 ml/m2, p<0.001; CI: 3.4±0.3 vs 1.9±0.3 l/min/m2, p<0.001), pulse pressure variation (PPV) increased (13.2±4.3 vs 22.1±4.3%, p<0.001). There was a decrease in oxygen delivery (464±45 vs 246±26.9 ml/min, p<0.001), central venous oxygen saturation (82.8±5.4 vs 53.6±12.1%, p<0.001) and increase in lactate levels (1.6±0.4 vs 3.5±1.6 mmol/l, p<0.005). SVI, CI and PPV returned to their initial values by t2. To normalize MAP fluid therapy had to be continued till t4, with the total infused volume of 4.5±0.8 l. CONCLUSION: In the current experiment bleeding led to hemorrhagic shock, while MAP remained higher than 65 mmHg. Furthermore, MAP was unable to indicate the normalization of SVI, CI and PPV that resulted in unnecessary fluid administration. Our data give further evidence that MAP may be an inappropriate parameter to follow during fluid resuscitation.

[Pathophysiology, clinical and experimental possibilities of pericardial tamponade]. / A pericardialis tamponád kórélettana, klinikuma és állatkísérletes vizsgálati lehetoségei.

Acute pericardial tamponade is one of the most emergent clinical scenarios in cardiac surgery. With numerous causes in the background, pericardial tamponade can lead to cardiogenic shock and death. In modern diagnostic era, the recognition of pericardial tamponade is simple, but its management and the long-term effects can still be challenging. Without the detailed understanding of the pathophysiological pathways diagnostic and therapeutic management plans of pericardial tamponade is very difficult. The aim of this review was to give a complex picture of pericardial tamponade, from its role in medical history to pathophysiology and its significance in surgical experimental models. Orv Hetil. 2018; 159(5): 163-167.

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.

Volume-replacement ratio for crystalloids and colloids during bleeding and resuscitation: an animal experiment.

BACKGROUND: Fluid resuscitation remains a cornerstone in the management of acute bleeding. According to Starling's "Three-compartment model", four-times more crystalloids have the same volume effect as colloids. However, this volume-replacement ratio remains a controversial issue as it may be affected by the degradation of the endothelial glycocalyx layer, a situation often found in the critically ill. Our aim was to compare colloid and crystalloid based fluid resuscitation during an experimental stroke volume index (SVI) guided hemorrhage and resuscitation animal model. METHODS: Anesthetized and mechanically ventilated pigs were randomized to receive a colloid (Voluven®,HES, n=15) or crystalloid (Ringerfundin®,RF, n=15) infusion. Animals were bled till baseline SVI (Tbsl) dropped by 50% (T0), followed by resuscitation until initial SVI was reached (T4) in four steps. Invasive hemodynamic measurements, blood gas analyses and laboratory tests were performed at each assessment points. Glycocalyx degradation markers (Syndecan-1/hematocrit ratio, Glypican/hematocrit ratio) were determined at Tbsl, T0 and T4. RESULTS: Similar amounts of blood were shed in both groups (HES group: 506±159 mls blood, RF group: 470±127 mls blood). Hemodynamic changes followed the same pattern without significant difference between the groups. Animals received significantly less resuscitation fluid in the HES compared to the RF-group: 425 [320-665], vs 1390 [884-1585] mls, p <0.001. The volume replacement ratio was 0.92 [0.79-1.54] for HES; and 3.03 [2.00-4.23] for the RF-group (p <0.001). There was no significant difference between the groups in the glycocalyx degradation markers. CONCLUSION: In this moderate bleeding-resuscitation animal model the volume-replacement ratio for crystalloids and colloids followed similar patterns as predicted by Starling's principle, and the glycocalyx remained intact. This indicates that in acute bleeding events, such as trauma or during surgery, colloids may be beneficial as hemodynamic stability may be achieved more rapidly than with crystalloids.

[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.

Mitochondria As Sources and Targets of Methane.

This review summarizes the current knowledge on the role of mitochondria in the context of hypoxic cell biology, while providing evidence of how these mechanisms are modulated by methane (CH4). Recent studies have unambiguously confirmed CH4 bioactivity in various in vitro and in vivo experimental models and established the possibility that CH4 can affect many aspects of mitochondrial physiology. To date, no specific binding of CH4 to any enzymes or receptors have been reported, and it is probable that many of its effects are related to physico-chemical properties of the non-polar molecule. (i) Mitochondria themselves can be sources of endogenous CH4 generation under oxido-reductive stress conditions; chemical inhibition of the mitochondrial electron transport chain with site-specific inhibitors leads to increased formation of CH4 in eukaryote cells, in plants, and in animals. (ii) Conventionally believed as physiologically inert, studies cited in this review demonstrate that exogenous CH4 modulates key events of inflammation. The anti-apoptotic effects of exogenously administered CH4 are also recognized, and these properties also suggest that CH4-mediated intracellular signaling is closely associated with mitochondria. (iii) Mitochondrial substrate oxidation is coupled with the reduction of molecular oxygen, thus providing energy for cellular metabolism. Interestingly, recent in vivo studies have shown improved basal respiration and modulated mitochondrial oxidative phosphorylation by exogenous CH4. Overall, these data suggest that CH4 liberation and effectiveness in eukaryotes are both linked to hypoxic events and redox regulation and support the notion that CH4 has therapeutic roles in mammalian pathophysiologies.

[Effects of complement C5a inhibitor therapy in animal models of non-occlusive mesenteric ischemia]. / Komplement C5a-antagonista-terápia hatása nem okklúzív mesenterialis ischaemia állatmodelljeiben.

INTRODUCTION: Non-occlusive mesenteric ischemia (NOMI) develops without anatomical causes. Early diagnosis is challenging and treatments are of questionable effectiveness. We investigated the role of complement activation in the pathophysiology of NOMI in animal models through the inhibition of complement C5a. MATERIALS AND METHODS: 60-min partial aortic occlusion (PAO; abdominal aorta, proximal to celiac trunk; mean arterial pressure: 30-40 mmHg) was established in Sprague-Dawley rats (n = 28) and 60-min cardiac tamponade in minipigs (n = 19; mean arterial pressure: 40-50 mmHg) to observe short- and long-term circulatory and inflammatory consequences of NOMI. Macro- and microhemodynamics, leukocyte infiltration, plasma levels of inflammatory mediators (endothelin, HMGB-1) were measured. C5a inhibitor (Acetyl-Peptid-A; 4 mg/kg iv) was administered at the 45th min of PAO or tamponade, respectively. RESULTS: Twenty-four hours after PAO systemic inflammatory response increased cardiac output and superior mesenteric artery flow (SMAF). C5a inhibition reduced the elevated cardiac output (203.1 ± 5 vs 269.6 ± 8.1 ml/min/kg) and SMAF and increased ileal microcirculation (833.5 ± 33.8 vs 441.9 ± 22.4 µm/s). In pigs, after the tamponade, C5a inhibition reduced the immediate hemodynamic disturbances, temporarily increased SMAF and permanently the ileal microcirculation. The Acetyl-Peptid-A treatment reduced leukocyte infiltration and plasma levels of inflammatory mediators in both NOMI models. CONCLUSIONS: Complement activation plays central role in the macro- and microcirculatory disturbance during NOMI. C5a inhibition reduces the inflammatory activation and influences the hemodynamic consequences of experimental NOMI.