Distant Organ Damage Research Articles

ORGAN SPECIFIC FORMATION OF NITROSYL COMPLEXES UNDER INTESTINAL ISCHEMIA/REPERFUSION IN RATS INVOLVES NOS-INDEPENDENT MECHANISM(S)

Intestinal ischemia/reperfusion may lead to local and distant organ damage involving nitric oxide (NO). NO rapidly reacts with heme/non-heme-iron-yielding nitrosyl complexes, which can be determined directly by electron paramagnetic resonance spectroscopy. The aim of the present study was to characterize nitrosylation reactions induced by transient intestinal ischemia in blood and tissues. We used electron paramagnetic resonance spectroscopy and reverse transcription polymerase chain reaction analyses to estimate nitrosyl complex levels and inducible NO synthase mRNA expression in rats subjected to superior mesenteric artery occlusion for 60 min followed by the reperfusion. Nitrosyl hemoglobin concentrations in circulating blood were significantly increased during ischemia and reperfusion. Nitrosyl hemoglobin complexes were detected in ischemic intestine, but not in normoxic lung and liver or reperfused intestine. Administration of N-G-monomethyl-L-arginine, a non-specific NO synthase inhibitor, did not affect the formation of circulating nitrosyl complexes. Moreover, inducible NO synthase mRNA was not found in intestinal tissues at 30 min of reperfusion. Our data suggest an organ-specific NO formation indicated by the increased nitrosylation reaction in ischemic intestinal tissue, but not in the distant normoxic organs, in spite of high circulating nitrosyl hemoglobin levels. NO involved in nitrosylation under intestinal ischemia/reperfusion is probably formed by NO synthase-independent mechanism(s).

Modulation of organ ICAM-1 expression during IV-TPN with glutamine and bombesin.

The gut primes neutrophils (PMNs) during injury, which can then induce distant organ damage after a second insult. ICAM-1 is an important adhesion molecule in PMN attachment to the vascular endothelium. Parenteral nutrition (TPN) decreases gut levels of interleukin (IL)-4 and IL-10, two cytokines that are normal inhibitors of ICAM-1 expression. TPN also increases gut ICAM-1 expression and PMN accumulation. Since glutamine (GLN) and bombesin (BBS) prevent TPN-associated impairment of mucosal immunity, we hypothesized that GLN and BBS would modulate organ ICAM-1 expression in association with normalization of IL-4 and IL-10 levels. Forty-four mice were fed chow, TPN, or GLN-TPN (isonitrogenous 2% GLN-enriched TPN). After 5 days of diets, ICAM-1 expression was quantified in organs using the dual radiolabeled monoclonal antibody technique. In the next experiment, 29 mice were fed chow, TPN, or BBS-TPN (BBS 15 microg/kg TID) for 5 days to measure organ ICAM-1 expression. Total IL-4 and IL-10 levels were measured with ELISA from intestinal homogenates of another set of 52 mice fed chow, TPN, GLN-TPN, or BBS-TPN. TPN significantly increased ICAM-1 expression in the lung, kidney, and intestine compared with chow mice. GLN-TPN decreased intestinal, but not lung, ICAM-1 expression, while BBS-TPN reduced pulmonary, but not gut, ICAM-1 levels. GLN- and BBS-TPN returned gut IL-4 levels to normal, but failed to increase IL-10 levels. GLN and BBS had different effects on organ ICAM-1 expression induced by lack of enteral nutrition. Mechanisms other than recovery of IL-4 alone may be responsible for gut ICAM-1 expression.

Acute pancreatitis

Efforts to unravel the intracellular processes that occur in acute pancreatitis continue. In cerulein pancreatitis, new evidence supports the idea that a very early event is premature trypsinogen activation triggered by lysosomal cathepsin B. Clinicians persist in trying to identify more sensitive and specific prognostic signs of the severity of attacks of pancreatitis; one study suggests that computer-based neural networks may be an alternative to biochemical markers and clinical scoring systems. The systemic severity of episodes of pancreatitis seems to be related to a multitude of proinflammatory cytokines and chemokines acting at sites distant from the pancreas. Selective blockade of some of these peptides (eg, endothelin-1 and platelet-activating factor) has decreased mortality and distant organ damage in animal models and may deserve clinical evaluation. Gene therapy may be more efficient than pharmacologic therapy in increasing anti-inflammatory cytokine (interleukin-10) levels. Clinical studies have further underlined the usefulness of prophylactic antibiotics in severe acute pancreatitis. Radiologic and endoscopic techniques may be alternatives to surgery for certain complications of pancreatitis (eg, infected necrosis and pseudocysts) in particular subsets of patients.

The expression of cellular adhesion molecules is upregulated and co-localized with the oxidative stress in the early course of experimental acute pancreatitis

Using a novel method to demonstrate histologically the production of oxygen free radicals (OFR-s), this study investigates the possible role of cellular adhesion molecules (CAM-s) -in relation to the oxidative stressduring the early course of acute necrotizing pancreatitis (ANP). Similarly to other inflammatory pathologies, injury to the pancreatic acini supposedly results in the expression/upregulation of CAM-s on the periacinar endothelial cells as well as release of proinflammatory mediators. The adherent lenkocytes, mostly neutrophils (PMN), become activated and release OFR-s, microbicidal enzymes and more mediators to strengthen the inflammatory response. An uncontrolled inflammatory cascade may become locally and systemically deleterious. We have developed a novel technique to detect the presence and localization of OFR-s in vivo, using the cerium capture method. Reaction of OFR-s with CeC13 leads to cerium-perhydroxide precipitation. These deposits can be detected histologically by their laser reflecting properties using confocal laser scanning microscopy (CLSM) in the reflectance mode (RM). METHODS: ANP was induced in Wistar rats by retrograde infusion of taurocholate into the pancreatic duct. At different time points (1, 2, 24h) the animals were re-laparotomized and perfused with CeC13 (20mM in Hartmann solution) through the abdominal aorta, then sacrificed. Normal rats received a CeCI 3 perfusion in the same fashion and were used as controls. Pancreata were snap frozen in liquid nitrogen. Indirect immunofluorescence (FITC fluorochrome) was performed on serial frozen sections to label E-selectin, P-selectin, ICAM-1, VCAM-1, and PECAM molecules. Nuclei were colored by propidium-iodide. Simultaneous observation of CAM expression, cerium reflectance and cell type definition was performed by CLSM using multichannel detection. RESULTS: The capillaries in the pancreata of normal animals showed weak, sparse P-selectin and ICAM-1 positivity, with a constitutive expression of PECAM. Reflectance signals were negligible. At the early time points (1, 2h) of pancreatitis the tissue architecture was found to be relatively well preserved, an increase in endothelial P-selectin, and ICAM-1 immunoreactivity was observed. Strong, shining reflectance could be detected in the pancreatic microvasculature, as well as cloud-like signals over certain groups of acini. Numerous leukocytes adherent to CAM positive capillary walls were seen, however they presented small, focal, mostly intracellular reflectance signals, which were often localized at the contact points between the CAM-s and leukocytes. At 24h the samples were characterized by intense PMN infiltration, heterogeneous necrosis, strong, mostly perinecrotic P-selectin, and ICAM-1, but moderately increased E-selectin, and VCAM-1 expression. Large numbers of adherent, or already transmigrated PMN-s showed abundant intraand pericellular reflectance signals. CONCLUSION: Pancreatic endothelial CAM-s are upregulated early in ANP, and may play a role -in addition to cytokinesin the activation of adhering leukocytes. At the earliest time points the major source of OFR seems to be the pancreatic cell (xanthine-oxidase), later the activated PMN-s, thereby possibly contributing to local and distant organ damage. The CAM over-expression showed a significant spatial co-localization with the oxidative stress. The work of G. Telek was supported by a grant from IRMAD Foundation, France.

Visceral Ischemia and Organ Dysfunction After Thoracoabdominal Aortic Aneurysm Repair

Repair of thoracoabdominal aortic aneurysms (TAAAs) is associated with significant postoperative morbidity and mortality. Reperfusion of acutely ischemic abdominal viscera in animals leads to release of multiple factors that cause local and distant organ damage, and similar phenomena occurring in humans after TAAA repair could contribute to the high morbidity/mortality and cost associated with this procedure. Twenty-nine patients undergoing elective TAAA repair were studied prospectively. Preoperative organ dysfunction and intraoperative risk factors (cross-clamp time, blood loss, operative time) were assessed and compared with postoperative organ dysfunction (defined as: pulmonary, positive pressure ventilation for > 7 days; renal, increase in serum creatinine > 2.0 mg/dL over baseline; hepatic, lactate dehydrogenase > 500 international units and total bilirubin > 3.0 mg/dL or serum transaminase level > 200 international units; hematopoietic, platelet count > 50 K or leukocyte count > 4.5 K, mortality, and costs. No relationship between preoperative organ dysfunction, blood loss, or operative time and postoperative organ dysfunction or mortality was seen; however, cross-clamp times > 40 minutes were associated with a significantly greater incidence of pulmonary (59%), renal (47%), hepatic (35%), and hematopoietic (47%) dysfunction. In addition, multiple-organ dysfunction (> 2 organ systems) was more common after > 40 minutes of visceral ischemia and led to significantly greater overall hospital ($88,465 + $76,155 vs. $41,782 + $31,244) and intensive care unit ($26,726 + $28,256 vs. $11,234 + $12,146) costs (p < 0.01, Mann-Whitney U test). Mortality associated with leukopenia was 67% compared with 4% without leukopenia (p < 0.01). Increasing durations of acute visceral ischemia led to significant multiple organ dysfunction after TAAA repair. Methods of limiting visceral ischemia or the systemic effects of visceral ischemia may decrease both the morbidity and mortality and the overall hospital cost associated with this procedure.