Antioxidant and calcium channel blockers counteract endothelial barrier injury induced by acute pancreatitis in rats

Whole body physiologically based modelling of β-blockers in the rat: events in tissues and plasma following an i.v. bolus dose

BACKGROUND AND PURPOSE

Whole body physiologically based pharmacokinetic (PBPK) models have been increasingly applied in drug development to describe kinetic events of therapeutic agents in animals and humans. The advantage of such modelling is the ability to incorporate vast amounts of physiological information, such as organ blood flow and volume, to ensure that the model is as close to reality as possible.

EXPERIMENTAL APPROACH

Previous PBPK model development of enantiomers of a series of seven racemic β-blockers, namely, acebutolol, betaxolol, bisoprolol, metoprolol, oxprenolol, pindolol and propranolol, together with S-timolol in rat was based on tissue and blood concentration data at steady state. Compounds were administered in several cassettes with the composition mix and blood and tissue sampling times determined using a D-optimal design.

KEY RESULTS

Closed-loop PBPK models were developed initially based on the application of open loop forcing function models to individual tissues and compounds. For the majority of compounds and tissues, distribution kinetics was adequately characterized by perfusion rate-limited models. For some compounds in the testes and gut, a permeability rate-limited distribution model was required to best fit the data. Parameter estimates of the tissue-to-blood partition coefficient through fitting of individual enantiomers and of racemic pair were generally in agreement and also concur with those from previous steady-state experiments.

CONCLUSIONS AND IMPLICATIONS

PBPK modelling is a very powerful tool to aid drug discovery and development of therapeutic agents in animals and humans. However, careful consideration of the assumptions made during the modelling exercise is essential.

Ultrastructural changes in the pulmonary mechanical barriers in a rat model of severe acute pancreatitis-associated acute lung injury

This study examined the ultrastructural changes in the pulmonary mechanical barriers in a rat model of severe acute pancreatitis (SAP)-associated acute lung injury (ALI). Animals were randomized into the SAP group (n = 60) and the control group (n = 60). SAP was induced by retrograde injection of 5% taurocholic acid into the biliopancreatic duct. The morphological abnormalities assessed by histology and the lung wet/dry weight ratio and the ultrastructural abnormalities assessed by transmission electron microscope and scanning electron microscope examinations plus lanthanum nitrate tracing were compared between the two groups at 6, 12, and 24 h post-SAP induction (n = 10/group/time point). The SAP group had significantly greater extravascular effusion than the control group at each time point as assessed by the lung wet/dry weight ratio (p < .001). The severity of the tissue damage increased in the lung and pancreas over time in the SAP group (all p < .001). In the SAP group, ultrastructural damages to the endothelial, epithelial, and pleural barriers were apparent and the damages to the endothelial barrier were detected earlier than the other two barriers, suggesting its fundamental role in preventing the further development of SAP-associated ALI. Moreover, the ultrastructural abnormalities were detected earlier than symptoms and morphological changes. The ultrastructural damages in the endothelial, epithelial, and pleural barriers occurred in the early stage of SAP. The endothelial barrier is likely to be the first line to prevent the further development in this rat model of SAP-associated ALI.

Free radicals and acute pancreatitis: much ado about … something

There is a convincing body of evidence that oxidative stress is involved in the pathogenesis of acute pancreatitis. The effects of different radical scavengers suggested that reactive oxygen metabolites are generated at very early stage of disease and contribute to amplify the pancreatic damage. Oxidative stress is also involved in the progression of the disease from a local damage to a systemic organ failure. However, therapeutic use of antioxidants failed to clearly show a clinical benefit in different trials. Therefore, although antioxidants alone seem to be not enough for the treatment of severe acute pancreatitis, future combined therapeutic strategies should include antioxidants in its composition.

Treatment of acute pancreatitis: focus on medical care

Acute pancreatitis has an incidence of about 300 per 1 million individuals per year, of which 10-15% of patients develop the severe form of the disease. Novel management options, which have the potential to improve outcome, include initial proper fluid resuscitation, which maintains microcirculation and thereby potentially decreases ischaemia and reperfusion injury. The traditional treatment concept in acute pancreatitis, fasting and parenteral nutrition, has been challenged and early initiation of enteral feeding in severe pancreatitis and oral intake in mild acute pancreatitis is both feasible and provides some benefits. There are at present no data supporting immunonutritional supplements and probiotics should be avoided in patients with acute pancreatitis. There is also no evidence of any benefits provided by prophylactic antibacterials in patients with predicted severe acute pancreatitis. A variety of specific medical interventions have been investigated (e.g. intense blood glucose monitoring by insulin) but none has become clinically useful. Lessons can probably be learned from critical care in general, but studies are needed to verify these interventions in acute pancreatitis.

Severe acute pancreatitis: Pathogenetic aspects and prognostic factors

Approximately 20% of patients with acute pancreatitis develop a severe disease associated with complications and high risk of mortality. The purpose of this study is to review pathogenesis and prognostic factors of severe acute pancreatitis (SAP). An extensive medline search was undertaken with focusing on pathogenesis, complications and prognostic evaluation of SAP. Cytokines and other inflammatory markers play a major role in the pathogenesis and course of SAP and can be used as prognostic markers in its early phase. Other markers such as simple prognostic scores have been found to be as effective as multifactorial scoring systems (MFSS) at 48 h with the advantage of simplicity, efficacy, low cost, accuracy and early prediction of SAP. Recently, several laboratory markers including hematocrit, blood urea nitrogen (BUN), creatinine, matrix metalloproteinase-9 (MMP-9) and serum amyloid A (SAA) have been used as early predictors of severity within the first 24 h. The last few years have witnessed a tremendous progress in understanding the pathogenesis and predicting the outcome of SAP. In this review we classified the prognostic markers into predictors of severity, pancreatic necrosis (PN), infected PN (IPN) and mortality.

Treatment with anti-factor VIIa in acute pancreatitis in rats: blocking both coagulation and inflammation?

OBJECTIVE

Acute pancreatitis starts as an autodigestive process restricted to the pancreas and progresses to a systemic inflammation via cytokine release into the blood stream. Several inhibitors of the coagulation cascade, including active-site-inactivated factor VIIa, have shown anti-inflammatory properties in other inflammatory models than acute pancreatitis. Free radical scavengers have proven useful in reducing the oxidative damage during hyperinflammatory conditions. The aim of this study was to investigate whether pretreatment with FVIIai would have any effect on the multiple organ dysfunction syndrome (MODS) in severe acute pancreatitis.

MATERIAL AND METHODS

Experimental acute pancreatitis was induced by intraductal infusion of taurodeoxycholate in the pancreatic duct. The animals were pretreated with N-acetyl-cysteine and active-site-inactivated factor VIIa. Neutrophil infiltration in the lungs, ileum and colon was quantified by myeloperoxidase activity. Inflammatory markers, IL-6 and MIP-2, were measured using ELISA.

RESULTS

Tissue infiltration of neutrophils in the lungs, ileum and colon significantly increased during acute pancreatitis as compared to sham operation. These levels were reduced by pretreatment with N-acetylcysteine and active-site-inactivated factor VIIa. Levels of interleukin-6 and macrophage inflammatory protein-2 increased significantly during acute pancreatitis. Pretreatment with NAC and FVIIai reduced these levels.

CONCLUSIONS

Both N-acetylcysteine and active-site-inactivated factor VIIa showed powerful anti-inflammatory properties in experimental acute pancreatitis. As they exert their effects through different physiological mechanisms, they represent potential candidates for future multimodal treatment of acute pancreatitis.

Immunomodulation in surgical practice

BACKGROUND

Immunomodulation may represent a potential way to improve surgical outcome. These types of interventions should be based on detailed knowledge of the underlying mechanisms involved. The aim of the present review is to summarize some experience on the acute phase response, potential ways of intervention and experiences from critical illness and HPB disease.

DISCUSSION

Mechanisms of the acute phase response are discussed including the individual parameters and local changes that take part. Mechanisms involved in failure of the gut barrier are presented and include changes in gut barrier permeability, effects on gut-associated immunocompetent cells, and systemic implications. As examples of HPB disease, mechanisms of the acute phase response and potential ways of intervention in obstructive jaundice and acute pancreatitis are discussed. Nutritional pharmacology and lessons learned from immunomodulation and immunonutrition in critical illness and major abdominal surgery, including upper GI and HPB surgery, are referred to. Overall, immunomodulation represents a potential tool to improve results but requires a thorough mapping of underlying mechanisms in order to achieve individualized treatment or prevention based on patients' specific needs.

Potential role of reactive oxygen species in pancreatitis-associated multiple organ dysfunction

BACKGROUND

Severe acute pancreatitis is still associated with substantial morbidity and mortality. Experimental and clinical studies have demonstrated that reactive oxygen species (ROS) represent early occurring inflammatory mediators contributing to cell dysfunction, both locally in the pancreas and remote organs.

METHOD

A systematic literature review was conducted to investigate the potential roles of intra- and intercellular, as well as interorgan signaling of ROS in the development of pancreatitis-associated multiple organ dysfunction syndrome (MODS). A text word search of the Medline, PubMed and Cochrane databases, and a manual search of the citations from these references, was performed.

RESULTS

ROS directly compromise cellular damage and regulate intercellular signals in pancreatitis-associated MODS. ROS are involved in leukocyte activation, production of cytokines, endothelial barrier dysfunction, and microcirculatory barrier dysfunction in acute pancreatitis. Beside effects on intercellular signaling, ROS also affect intracellular events and activate the transcription factor nuclear factor kappa B that regulates inflammatory cytokine expression.

CONCLUSION

ROS is a critical factor responsible for the development of pancreatitis-induced remote organ dysfunction via intercellular and interorgan signaling. The role of antioxidant treatment, included as a part of multimodal management, remains to be investigated.

Disruption of the blood-brain barrier during TNBS colitis

Well-documented central nervous system changes during colitis suggest possible alterations of blood-brain barrier (BBB) permeability, yet the integrity of the BBB has not been fully evaluated in experimental colitis. Our aim was to investigate whether trinitrobenzene sulphonic acid (TNBS) colitis was associated with an increase in the permeability of the BBB. Sprague-Dawley rats were given an intracolonic injection of saline or TNBS and studied 1, 2, 3, 7 and 21 days after treatment. The extravasation of endogenous immunoglobulin G, a large molecule, was not altered at any time after TNBS treatment. In contrast, significant increases in the BBB leakage of sodium fluorescein, a much smaller molecule, were observed 1 and 2 days after the induction of colitis, in and around the circumventricular organs; the organum vasculosum of the lamina terminalis, subfornical organ and median eminence of the hypothalamus. TNBS-treated rats also exhibited sodium fluorescein leakage in focal areas in the brain parenchyma. The expression of endothelial barrier antigen, a protein associated with the BBB, was reduced about 60% 48 h after the induction of colitis. This returned to control values by 3 weeks, when colitis had largely subsided. In conclusion, experimental colitis transiently increased permeability of the brain to small molecules through a mild disruption of the BBB.

Tissue Distribution of Basic Drugs: Accounting for Enantiomeric, Compound and Regional Differences Amongst β-Blocking Drugs in Rat

The purpose of this research was to identify the major factors controlling the distribution of beta-blockers (acebutolol, betaxolol, bisoprolol, metoprolol, oxprenolol, pindolol, propranolol and timolol) in rats, across tissues, compounds and enantiomers. Tissue distribution was assessed at steady state by infusing cassette doses of beta-blockers into the jugular vein via an indwelling catheter at a constant rate. Blood was sampled via an indwelling catheter in the carotid artery, and 12 tissues excised at the end of dose infusion (4 or 8 h). Drug concentrations were quantified using a novel chiral LC-MS method and the tissue-to-plasma (Kp) and tissue-to-plasma water (Kpu) values were calculated for each tissue. Differences between Kp were observed between many enantiomeric pairs, and largely explained by enantiomeric differences in plasma protein binding. Across compounds, Kpu values were generally highest in lung and lowest in adipose, and were higher for the more lipophilic drugs betaxolol and propranolol. For any tissue, Kpu differences between the individual beta-blockers correlated well with the corresponding affinity for blood cells. For all compounds, regional tissue distribution correlated well with tissue acidic phospholipid concentrations, with phosphatidylserine appearing to have the strongest influence. This information may be used as the basis for predicting the tissue distribution of basic drugs.

Severity of pancreatitis-associated gut barrier dysfunction is reduced following treatment with the PAF inhibitor lexipafant

The aim of the present study was to investigate the potential effect of treatment with a platelet-activating factor (PAF) antagonist, lexipafant (BB-882), on gut endothelial and epithelial barrier dysfunction and leukocyte recruitment in rats with acute pancreatitis. Severe acute pancreatitis was induced by the intraductal administration of 5% sodium taurodeoxycholate and pancreatitis-associated gut barrier dysfunction was characterized by increased exudation of radiolabelled albumin into the interstitium and alterations in bidirectional (over both the endothelial and epithelial barrier components) permeability of the intestine at the early stage of bile salt-induced acute pancreatitis. Levels of interleukin 1beta and 6, ileal and colonic myeloperoxidase (MPO) content, clearance of radiolabelled albumin from blood to the gut lumen or gut lumen to blood, and leakage of radiolabelled albumin to the ileum or colon were measured 3 and 12h after induction of acute pancreatitis. Treatment with lexipafant 30 min and 6h after pancreatitis reduced severity of pancreatitis-associated intestinal dysfunction, associated with a diminish in systemic concentrations of IL-1 and local leukocyte recruitment. The findings imply that PAF plays a critical role in the development of pancreatitis-associated gut barrier dysfunction and that PAF antagonist in some forms may represent potential candidates for future therapeutic intervention.

Soluble CD14 receptor expression and monocyte heterogeneity but not the C-260T CD14 genotype are associated with severe acute pancreatitis

OBJECTIVE

Soluble CD14 is derived from a membrane glycoprotein, and it enhances endothelial cytokine responses to lipopolysaccharide. We studied the role of soluble CD14 in the pathogenesis of the systemic inflammatory response associated with acute pancreatitis, to determine whether altered expression was due to a functional C-260T polymorphism in the CD14 promoter gene or altered monocyte heterogeneity.

DESIGN

Prospective case-matched study.

SETTING

Tertiary pancreatic treatment unit in the United Kingdom.

SUBJECTS

Patients with pancreatitis and controls.

INTERVENTIONS

DNA from 117 patients with pancreatitis (34 severe) and 263 controls underwent CD14 genotyping using restriction fragment length polymorphism-polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Peripheral venous blood samples at 24 and 72 hrs after the onset of abdominal pain were analyzed for sCD14 levels. Isolated peripheral blood mononuclear cells were phenotyped for CD14/CD16 receptor expression using immunofluorescence flow cytometry. Disease severity was assessed using Atlanta criteria, Acute Physiology Scores, and C-reactive protein.Soluble CD14 levels were higher in severe (24-hr median, 66.6 ng/mL; 72-hr median, 72.2 ng/mL) compared with mild attacks (24-hr median, 50.7 ng/mL; 72-hr median, 49.7 ng/mL, p < .001), although the latter was similar to controls (median, 51 ng/mL). Furthermore, soluble CD14 levels correlated with Acute Physiology Scores (p < .001) and C-reactive protein (p = .01).Peripheral blood mononuclear cells CD14++ (p = .008), CD14+/16+ (p = .003), and CD16++ (p = .015) receptor densities were all increased in severe attacks at 24 hrs. Early CD14+/16+ receptor density correlated with sCD14 (p < .001), Acute Physiology Scores (p < .001), and C-reactive protein (p = 0.006). The CD14 genotype prevalence in acute pancreatitis was similar to controls and failed to correlate with any variables studied.

CONCLUSIONS

Increased soluble CD14 expression is associated with the systemic inflammatory response to acute pancreatitis and an expansion of the proinflammatory CD14+/CD16+ monocyte subset. Its targeted disruption may afford some benefit in preventing the development of systemic complications.

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Multimodal management - of value in fulminant acute pancreatitis?

BACKGROUND

The multiple organ dysfunction syndrome (MODS) is the major cause of morbidity and mortality associated with acute pancreatitis. Presently, therapy is merely organ supportive as no effective therapy against underlying causative pathophysiological mechanisms exists.

AIMS

To evaluate the effect of treatment with a platelet-activating factor inhibitor (PAFI), a monoclonal antibody against platelet endothelial cell adhesion molecule 1 (PECAM-1-MAb) and an oxygen free radical scavenger (N-acetylcystein; NAC), alone or in combination, on systemic organ dysfunction in experimental acute pancreatitis.

METHODS

Severe acute pancreatitis was induced in rats by the intraductal administration of taurodeoxycholate. Treatment was given after 1 or 3 h, and evaluations were performed 6 h after induction. Organ dysfunction was evaluated by means of endothelial integrity impairment expressed as endothelial barrier leakage index.

RESULTS

Severe acute pancreatitis caused a significant impairment in endothelial integrity in all organs studied and decreased levels of protease inhibitors compared to controls. The endothelial barrier impairment was significantly ameliorated by all treatment modalities, either given early or later. Combinations of NAC and the PECAM-1-MAb or the PECAM-1-MAb and the PAFI were the only schedules to restore endothelial barrier integrity to normal levels in most of the organs studied.

CONCLUSION

Combination therapy with NAC and PECAM-1-MAb and/or PAFI may offer effective, causative-directed supplements to organ-supportive therapy of MODS in severe acute pancreatitis.

Deferoxamine and meropenem combination therapy in experimental acute pancreatitis

INTRODUCTION

Recent data from the experimental clinical studies suggest that antibiotics having good penetration to pancreas may reduce mortality by preventing pancreatic infection, which is the most important prognostic factor in acute pancreatitis (AP). Deferoxamine is an active free oxygen radical scavenger, which has been shown to have a protective role in development of acute pancreatitis.

AIM

To determine the effects of combination of deferoxamine and meropenem in acute necrotizing pancreatitis.

METHODOLOGY

One hundred male Sprague-Dawley rats were randomly divided into 5 groups. All rats underwent laparotomy with cannulation of biliopancreatic duct. Group 1 received intraductal saline injection. Acute necrotizing pancreatitis was induced in group 2, 3, 4, and 5 by intraductal injection of 3% taurocholate. Group 1 (sham operated) and group 2 were injected with saline of 0.3 mL/kg intraperitoneally (i.p). Group 3 was injected with meropenem 60 mg/kg/d i.p, group 4 with deferoxamine 80 mg/kg/d s.c and group 5 with combination of these 2 agents at the same doses. While meropenem was started 2 hours later, all treatments were started immediately after the induction of pancreatitis. All rats were killed at the 48th hour of the treatment and blood and tissue samples were collected for amylase determinations, pathologic examinations, and culture.

RESULTS

There was no difference in serum amylase levels between AP induced groups (P > 0.05). Pancreatic histology scores were significantly low in rats treated with deferoxamine (group 4), and combination regimen (group 5) (P < 0.001). Meropenem significantly reduced the incidence of pancreatic infection. Although combination of deferoxamine with meropenem showed better effects than meropenem alone in terms of pancreatic infection, the difference did not reach to statistical significance.

CONCLUSIONS

Meropenem treatment reduces secondary pancreatic infections in acute pancreatitis. Treatment with deferoxamine and meropenem combination may be more beneficial than single therapies in reducing the severity of pancreatitis. Further studies investigating the effects of this combination on survival are needed.

Acute lung injury in experimental pancreatitis in rats: pulmonary protective effects of crotapotin and N-acetylcysteine

Respiratory complications are major factors contributing to death in acute pancreatitis. However, the mechanisms of these pulmonary complications are not completely elucidated. We studied the effects of pretreatment with purified crotapotin (a phospholipase A2 inhibitor), N-acetylcysteine (a reactive oxygen species inhibitor), and a combination of both on the pulmonary mechanical and morphometric changes secondary to severe acute necrohemorrhagic pancreatitis in Wistar rats. A total of 69 male Wistar rats were studied. Pancreatitis was induced by infusion of 0.5 mL of a 4% solution of sodium taurocholate into the biliopancreatic duct. Crotapotin, N-acetylcysteine, or a combination of both was given intraperitoneally 30 min before inducing pancreatitis. Data were compared with data from sham-operated animals with or without those pretreatments. The severity of pancreatic and pulmonary injuries was evaluated 4 h after inducing pancreatitis by morphometric and pulmonary mechanical studies. N-acetylcysteine prevented the development of alveolar edema, alveolar distention, and collapse. Crotapotin prevented alveolar distention and collapse, and pulmonary dynamic elastance increase. When used in combination, crotapotin and N-acetylcysteine prevented both pulmonary morphological and mechanical changes induced by acute pancreatitis, suggesting an increase in protective effect when these drugs are used together compared with individual effects. However, the severity of pancreatic necrosis and the increase in polymorphonuclear cells in alveolar septa induced by pancreatitis were not reduced by previous administration of crotapotin, N-acetylcysteine, or both. These results suggest that the protective effects of these drugs are probably due to an extra-pancreatic action in the circulation, or even directly in the lung.

Early treatment with lexipafant, a platelet-activating factor-receptor antagonist, is not sufficient to prevent pulmonary endothelial damage after intestinal ischaemia and reperfusion in rats

BACKGROUND

Intestinal ischaemia-reperfusion can lead to pulmonary injury characterised by increased macromolecular leakage and leukocyte sequestration. Important mediators of ischaemia-reperfusion-associated injury include polymorphonuclear granulocytes and platelet-activating factor.

AIM

To investigate the potential therapeutic inhibition of platelet-activating factor in intestinal ischaemia-reperfusion associated pulmonary injury, by use of a potent platelet-activating factor-receptor antagonist, lexipafant.

METHODS

Rats were subjected to 30 minutes of intestinal ischaemia followed by 3 or 12 hours reperfusion. Lexipafant or saline was given intraperitoneally after 30 minutes reperfusion.

RESULTS

Increased leakage of radiolabelled human serum albumin was found in the lungs after intestinal ischaemia followed by 3 or 12 hours reperfusion. Administration of lexipafant did not significantly prevent the increased leakage. Pulmonary myeloperoxidase content increased after intestinal ischaemia-reperfusion, indicating polymorphonuclear granulocyte sequestration through the pulmonary endothelium. The increase in interleukin-1beta seen after 3 hours reperfusion was partly reversed by lexipafant.

CONCLUSIONS

Pulmonary injury occurred following intestinal ischaemia-reperfusion, characterised by increased leakage of radiolabelled albumin over the endothelial barrier; correlating with increased pulmonary myeloperoxidase-content, implying involvement of polymorphonuclear granulocytes in the pathogenesis of remote organ injury after intestinal ischaemia-reperfusion. Lexipafant did not significantly decrease severity of pulmonary damage.

Minor role of oxidative stress during intermediate phase of acute pancreatitis in rats

Reactive oxygen species have been implicated in the pathogenesis of acute pancreatitis. Few studies have focused on the loss of endogenous antioxidants and molecular oxidative damage. Two acute pancreatitis models in rats; taurocholate (3% intraductal infusion) and cerulein (10 microg/kg/h), were used to study markers of oxidative stress: Glutathione, ascorbic acid, and their oxidized forms (glutathione disulfide and dehydroascorbic acid), malondialdehyde, and 4-hydroxynoneal in plasma and pancreas, as well as 7-hydro-8-oxo-2'-deoxyguanosine in pancreas. In both models, pancreatic glutathione depleted by 36-46% and pancreatic ascorbic acid depleted by 36-40% (p <.05). In the taurocholate model, plasma glutathione was depleted by 34% (p <.05), but there were no significant changes in plasma ascorbic acid or in plasma and pancreas dehydroascorbic acid, malondialdehyde, and 4-hydroxynoneal, and no significant changes in the pancreas glutathione disulfide/glutathione ratio. While pancreas glutathione disulfide/glutathione ratio increased in the cerulein model, there were no significant changes in plasma glutathione, plasma, or pancreas ascorbic acid, dehydroascorbic acid, 4-hydroxynoneal, and malondialdehyde, or in pancreas 7-hydro-8-oxo-2'-deoxyguanosine. Reactive oxygen species have a minor role in the intermediate stages of pancreatitis models.

Lymphocytic intracellular calcium in a patient with complicated verapamil overdose

Overdose with calcium channel blockers (CCBs) may lead to serious complications. CCBs act by blocking calcium entry into the cell, thus lowering intracellular calcium ([Ca2+]i). [Ca2+]i during CCB overdose has not yet been reported. We measured [Ca2+]i in lymphocytes of a patient with acute verapamil overdose with a complex clinical picture. A 59-year-old woman was admitted after a suicidal ingestion of 7200 mg of a sustained-release verapamil preparation. She presented with hypotension, complete atrioventricular block, stupor, hypokalemia, and hyperglycemia. Acute oliguric renal failure, acute pancreatitis, and the adult respiratory distress syndrome further complicated her medical course. Treatment was supportive and she recovered completely. Intracellular calcium ([Ca2+]i) was measured in the patient's lymphocytes using a spectrofluorometer with the calcium-sensitive dye Fura-2-acetoxymethyl ester. Thirty nine hours after the ingestion, [Ca2+]i was low at 52 nM (compared with 80 nM in a healthy control subject). Lymphocytic [Ca2+]i did not respond to stimulation with phytohemagglutinin (PHA). Fourteen days after the verapamil overdose, after the patient had recovered completely, lymphocytic [Ca2+]i was still low at 55 nM. At this time, there was an incomplete response to PHA in the lymphocytes. Three months after the ingestion, [Ca2+]i was normal, with a normal response to PHA. Verapamil overdose may run a complex clinical course, but full recovery is to be hoped for with full supportive care. Cellular intoxication, as reflected by low lymphocytic [Ca2+]i, is prolonged and lags behind the clinical recovery by weeks.

Treatment with lexipafant ameliorates the severity of pancreatic microvascular endothelial barrier dysfunction in rats with acute hemorrhagic pancreatitis

CONCLUSION

Treatment with lexipafant reduced the severity of pancreatitis-associated endothelial barrier compromise, also associated with a decrease in systemic concentrations of interleukin (IL) 1. Thus, the present findings imply that platelet-activating factor (PAF) may play an important role in the pathogenesis of pancreatic endothelial dysfunction by signaling and triggering the production and release of certain cytokines.

BACKGROUND

Pancreatic capillary endothelial barrier dysfunction is an initial and characteristic feature of acute pancreatic injury and pancreatitis. PAF, a proinflammatory mediator and an intercellular signaling substance, has been considered to be involved in the inflammatory reaction and the systemic endothelial dysfunction of acute pancreatitis.

METHODS

The development of pancreatic capillary endothelial barrier dysfunction was monitored by tissue edema and exudation of plasma albumin into the interstitium, 3 and 12 h after induction of acute pancreatitis by intraductal infusion of 5% sodium taurodeoxycholate in rats. Pancreatic leukocyte recruitment was reflected by measuring myeloperoxidase activity. Serum levels of IL-1 beta and IL-6 were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Pretreatment with lexipafant, a potent PAF receptor antagonist, significantly reduced the pancreatitis-induced increase in pancreatic endothelial barrier dysfunction, pancreatic leukocyte recruitment and serum levels of IL-1 beta, although a difference persisted between animals with sham operation and pancreatitis.

In vivo modulation of rodent glutathione and its role in peroxynitrite-induced neocortical synaptosomal membrane protein damage

Peroxynitrite, formed by the reaction between nitric oxide and superoxide, leads to the oxidation of proteins, lipids, and DNA, and nitrates thiols such as cysteine and glutathione, and amino acids like tyrosine. Previous in vitro studies have shown glutathione to be an efficient scavenger of peroxynitrite, protecting synaptosomal membranes from protein oxidation, the enzyme glutamine synthetase from inactivation, and preventing the death of hippocampal neurons in culture. The current study was undertaken to see if in vivo modulation of glutathione levels would affect brain cortical synaptosomal membrane proteins and their subsequent reaction with peroxynitrite. Glutathione levels were depleted, in vivo, by injecting animals with 2-cyclohexen-1-one (CHX, 100 mg/kg body weight), and levels of glutathione were enhanced by injecting animals with N-acetylcysteine (NAC, 200 mg/kg body weight), which gets metabolized to cysteine, a precursor of glutathione. Changes in membrane protein conformation and structure in synaptosomes subsequently isolated from these animals were examined using electron paramagnetic resonance, before and after in vitro addition of peroxynitrite. The animals injected with the glutathione depletant CHX showed greater damage to the membrane proteins both before and after peroxynitrite treatment, compared to the non-injected controls. The membrane proteins from animals injected with NAC were comparable to controls before peroxynitrite treatment and were partially protected against peroxynitrite-induced damage. This study showed that modulation of endogenous glutathione levels can affect the degree of peroxynitrite-induced brain membrane damage and may have potential therapeutic significance for oxidative stress-associated neurodegenerative disorders.

Inhibition of platelet-activating factor, intercellular adhesion molecule 1 and platelet endothelial cell adhesion molecule 1 reduces experimental pancreatitis-associated gut endothelial barrier dysfunction

BACKGROUND

Endothelial barrier dysfunction is a critical link in the development of tissue injury and organ dysfunction, via upregulation and exposure of adhesion molecules, intercellular signals and leucocyte-endothelial cell interactions. Inhibitors of inflammatory mediators and receptors have been suggested as a means of downregulating the cascade of both local and systemic inflammation.

METHODS

The potential therapeutic inhibition of platelet-activating factor (PAF), intercellular adhesion molecule (ICAM) 1 and platelet endothelial cell adhesion molecule (PECAM) 1 was investigated in pancreatitis-associated gut endothelial dysfunction in rats, by treatment with a PAF antagonist (lexipafant, BB-882) and monoclonal antibodies against rat ICAM-1 (anti-ICAM1-Mb) and PECAM (anti-PECAMA1-Mb). Alterations in gut endothelial barrier dysfunction and leucocyte recruitment, and systemic levels of interleukins were evaluated.

RESULTS

Plasma exudation measured by the albumin leakage index and tissue leucocyte recruitment in the distal small intestine and colon increased significantly 12 h after induction of pancreatitis and treatment with saline. These alterations were to varying degrees counteracted by treatment with lexipafant, anti-ICAM1-Mb or anti-PECAM1-Mb. Alterations in levels of interleukin (IL) 1 paralleled the changes in gut endothelial barrier dysfunction and leucocyte trapping.

CONCLUSION

Treatment with lexipafant and monoclonal antibodies against ICAM-1 or PECAM-1 reduced the severity of pancreatitis-associated gut endothelial dysfunction, and decreased systemic concentrations of IL-1 and local leucocyte recruitment.

Treatment with lexipafant ameliorates the severity of pancreatic microvascular endothelial barrier dysfunction in rats with acute hemorrhagic pancreatitis

CONCLUSION

Treatment with lexipafant reduced the severity of pancreatitis-associated endothelial barrier compromise, also associated with a decrease in systemic concentrations of interleukin (IL) 1. Thus, the present findings imply that platelet-activating factor (PAF) may play an important role in the pathogenesis of pancreatic endothelial dysfunction by signaling and triggering the production and release of certain cytokines.

BACKGROUND

Pancreatic capillary endothelial barrier dysfunction is an initial and characteristic feature of acute pancreatic injury and pancreatitis. PAF, a proinflammatory mediator and an intercellular signaling substance, has been considered to be involved in the inflammatory reaction and the systemic endothelial dysfunction of acute pancreatitis.

METHODS

The development of pancreatic capillary endothelial barrier dysfunction was monitored by tissue edema and exudation of plasma albumin into the interstitium, 3 and 12 h after induction of acute pancreatitis by intraductal infusion of 5% sodium taurodeoxycholate in rats. Pancreatic leukocyte recruitment was reflected by measuring myeloperoxidase activity. Serum levels of IL-1 beta and IL-6 were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Pretreatment with lexipafant, a potent PAF receptor antagonist, significantly reduced the pancreatitis-induced increase in pancreatic endothelial barrier dysfunction, pancreatic leukocyte recruitment and serum levels of IL-1 beta, although a difference persisted between animals with sham operation and pancreatitis.

Serum creatinine and chest radiographs in the early assessment of acute pancreatitis

BACKGROUND

We previously identified serum creatinine values >2 mg/dL (176.8 micromol/L) and pathological chest radiographs due to the presence of pleural effusions or pulmonary densifications as two early prognostic factors of life-threatening acute pancreatitis (AP). The aim of the present study was to validate their prognostic efficacy in combination.

METHODS

We analyzed as prognostic factors only the data obtained within 24 hours of admission in 539 cases of AP, including 163 patients (30.2%) with acute necrotizing pancreatitis (NP). Eleven patients (2%) presented with infected pancreatic necrosis, and 20 patients (3.7%) died.

RESULTS

One hundred and nine cases (20.2%) presented pathological chest radiographs: 32 (5.9%) pulmonary densifications and 77 (14.3%) pleural effusions (18 right, 25 left, 34 bilateral). Fifty-one patients (9.5%) had serum creatinine values >2 mg/dL. Pathological chest radiographs and serum creatinine values >2 mg/dL were significantly associated both with mortality risk (P <0.00001), with a diagnosis of NP (P <0.00001), and with risk of developing infected necrosis (P <0.0001). Considering positivity of either or both tests, the mortality risk sensitivity was 90% (95% confidence interval [CI] 70.7 to 98.3) with a specificity of 76% (CI 72.5 to 79.8), for the NP diagnosis the sensitivity was 60% (CI 52.5 to 67.4) and the specificity 88% (CI 85.0-91.5), whereas for the risk of infected necrosis the sensitivity was 73% (CI 42.2 to 92.6) and specificity 75% (CI 70.1 to 78.4). These data are comparable to those obtained with the Ranson or Glasgow scores at 24 hour in this patient group, with a cut-off > or =3.

CONCLUSIONS

Serum creatinine and chest radiographs are two indices capable of identifying, within 24 hour of admission, a subgroup of acute pancreatitis patients with a more severe or adverse clinical course.

Ischaemia-reperfusion injury to the intestine

Ischaemia-reperfusion injury (IRI) is of obvious relevance in situations where there is an interruption of blood supply to the gut, as in vascular surgery, or in the construction of free intestinal grafts. It is now appreciated that IRI also underlies the guy dysfunction that occurs in early shock, sepsis, and trauma. The events that occur during IRI are complex. However, recent advances in cellular biology have started to unravel these underlying processes. The aim of this review is to provide an outline of current knowledge on the mechanisms and consequences of IRI. Initially, IRI appears to be mediated by reactive oxygen metabolites and, at a later stage, by the priming and activation of polymorphonuclear neutrophils (PMN). Ischaemia-reperfusion injury can diminish the barrier function of the gut, and can promote an increase in the leakage of molecules (intestinal permeability) or the passage of microbes across the wall of the bowel (bacterial translocation). Ischaemia-reperfusion injury to the gut can result in the generation of molecules that may also harm distant tissues.

Experimental acute pancreatitis results in increased blood-brain barrier permeability in the rat: a potential role for tumor necrosis factor and interleukin 6

Pancreatic encephalopathy is a severe complication of acute pancreatitis. Proinflammatory cytokines may play a role in the development of multi-organ failure during pancreatitis. In the present study, we measured the changes in the blood-brain barrier (BBB) permeability concomitantly with the determination of serum tumor necrosis factor (TNF) and interleukin-6 (IL-6) levels in rats before, as well as 6, 24 and 48 h after the beginning of intraductal taurocholic acid-induced acute pancreatitis. Cytokine concentrations were measured in bioassays with specific cell lines (WEHI-164 for TNF and B-9 for IL-6), while the BBB permeability was determined for a small (sodium fluorescein, molecular weight (MW) 376 Da), and a large (Evans' blue-albumin, MW 67000 Da) tracer by spectrophotometry in the parietal cortex, hippocampus, striatum, cerebellum and medulla of rats. The serum TNF level was significantly (P < 0.05) increased 6 and 24 h after the induction of pancreatitis, while the IL-6 level increased after 24 and 48 h. A significant (P < 0.05) increase in BBB permeability for both tracers developed at 6 and 24 h in different brain regions of animals with acute pancreatitis. We conclude that cytokines, such as TNF and IL-6, may contribute to the vasogenic brain edema formation during acute pancreatitis.

Tissue water content in rats measured by desiccation

Tissue water content was determined by desiccation to constant weight at 40 degrees-50 degrees C in 14 tissues from two groups of rats weighing 200-250 and 270-430 g, respectively. The water content (mean +/- SE; ml/g) was highest in testes (0.861 +/- 0.002) and lowest in adipose (0.183 +/- 0.017) followed by bone (0.446 +/- 0.017) and skin (0.651 +/- 0.007). The average water content in the remaining tissues was 0.763 (+/- 0.003). Upon correction for the water content of residual tissue blood, significant difference between the uncorrected and corrected tissue water was observed for spleen, lungs, kidneys, heart, liver, and brain. Tissue water was independent of body weight, and was the same for right and left kidneys as well as testes and bone. Whereas the position of the muscle (back, abdomen, hindlimb) and adipose tissue (perirenal and subcutaneous) had no influence on water content, for skin, a slight difference was found between back and abdomen. In general, the current results are in agreement with composite literature values, but provide in one study data for all tissues used in the development of physiologically based pharmacokinetic models of rat.