Christina Tsigalou

Organ Toxicity and Mortality in Propofol-Sedated Rabbits Under Prolonged Mechanical Ventilation

BACKGROUND: Prolonged administration of propofol at large doses has been implicated in propofol infusion syndrome in intensive care unit patients. In this study we investigated organ toxicity and mortality of propofol sedation at large doses in prolonged mechanically ventilated rabbits and determined the role of propofols lipid vehicle. METHODS: Eighteen healthy male rabbits were endotracheally intubated and sedated with propofol 2% (Group P), sevoflurane (Group S) or sevoflurane while receiving Intralipid 10% (Group SI). Sedation lasted 48 h or until death (Group P) or the maximum surviving period of Group P (Groups S and SI). The initial propofol infusion rate (20 mg · kg−1 · h−1) or sevoflurane concentration (1.5%) was adjusted, if needed, to maintain a standard level of sedation. Blood biochemical analysis was performed in serial blood samples and histologic examination in the heart, lungs, liver, gallbladder, kidneys, urinary bladder, and quadriceps femoris muscle at autopsy. RESULTS: The mortality rate was 100% (surviving period, 26–38 h) for Group P, whereas 0% for Groups S and SI. The initial propofol infusion rate had to be increased up to 65.7 ± 4.6 mg · kg−1 · h−1 and sevoflurane concentration up to 4%. Serum liver function indices, lipids and creatine kinase were significantly increased (P < 0.05) in Groups P and SI and lactate was increased only in Group P, whereas amylase was increased in all groups. In Group P, histologic examination revealed myocarditis, pulmonary edema with interstitial pneumonia, hepatitis, steatosis, and focal liver necrosis, cholangitis, gallbladder necrosis, acute tubular necrosis of the kidneys, focal loss of the urinary bladder epithelium, and rhabdomyolysis of skeletal muscles; in Group S, low-grade bronchitis and incipient inflammation of the liver and the kidneys; and in Group SI, low-grade bronchitis, liver steatosis and hepatitis, and incipient inflammation of the gallbladder, kidneys, and urinary bladder. CONCLUSIONS: Continuous infusion of 2% propofol at large doses for the sedation of rabbits undergoing prolonged mechanical ventilation induced fatal multiorgan dysfunction syndrome similar to the propofol infusion syndrome seen in humans. Our novel findings including lung, liver, gallbladder, and urinary bladder injury were also noted. The role of propofols lipid vehicle in the manifestation of the syndrome was minor. Sevoflurane proved to be a safe alternative medication for prolonged sedation.

Effects of Cigarette Smoke Exposure and Its Cessation on Body Weight, Food Intake and Circulating Leptin, and Ghrelin Levels in the Rat

INTRODUCTION Smoking is associated with loss of body weight (BW) and reduced appetite, while smoking abstinence with the opposite effect. The role of peripheral signaling by appetite-controlling hormones leptin and ghrelin is not clear. In the present study, the relationship of circulating leptin and ghrelin with BW and food intake rate (FIR) changes was studied during cigarette smoke exposure (CSE) and after its cessation in the rat. METHODS Male Wistar rats were subjected to CSE for 8 weeks by confinement to plexiglass chambers (Group S). Control animals were confined to identical chambers without smoke (Group C). During CSE and an equivalent follow-up period, BW and FIR was recorded and serum leptin and ghrelin levels were measured. RESULTS A sharp decrease in BW was noted during the first 4 weeks of CSE, while FIR, after a substantial decrease noted at Week 1, returned to control levels. Thereafter, rats started to regain their BW until they reached control levels by the 1st week postCSE. BW regain was accompanied by a rebound increase of FIR, which plateaued during the first 4 weeks postCSE and then normalized. Serum leptin was decreased in Group S during both periods, normalizing at the 7th week postCSE. Ghrelin levels did not differ between groups. CONCLUSIONS Circulating leptin could not explain by its own BW and FIR changes during the first few week of CSE in rats, in contrast to the rest of the CSE period as well as after its cessation. Serum ghrelin levels did not justify BW and FIR changes.

Liver Regeneration Following Radiofrequency Ablation

BACKGROUND Radiofrequency ablation (RFA) of the liver leads to reduction of liver parenchymal volume. We sought to evaluate the regenerative response of the liver following RFA. MATERIALS AND METHODS Thirty healthy New Zealand white rabbits were subjected to a single session liver RFA using a cool-tip electrode after midline laparotomy. The regenerative process of the liver was assessed at various time-points (0 h, 48 h, 1 wk, 3 wk, 10 wk) in terms of computed tomography-based liver volume measurements, histological examination, hepatocyte mitotic activity, and serum biochemistry. RESULTS According to computed tomography-measurements, intact liver volume was gradually restored to the initial liver volume by the 10th week, while liver ablated volume was confined down to 50% of the initial ablated volume. At histology, inflammation, edema, and hepatocellular necrosis in the intact liver parenchyma, noted at 48 h, started to regress by 1 wk. Mitotic activity, initiated by 48 h, was substantially increased at 1 wk and remained high up to the 10th week. Serum transaminase levels were elevated up to 1 wk. CONCLUSIONS Liver RFA triggers a slow but sustained regenerative response of the liver with subsequent delayed restoration of parenchymal volume, while the ablated volume is gradually condensed.

Bacterial translocation in a rat model of large volume hepatic radiofrequency ablation.

BACKGROUND In this experimental study, we investigated the possibility of bacterial translocation, constituting a potential cause of infectious complications, after performing large volume hepatic radiofrequency ablation (RFA). MATERIALS AND METHODS Wistar rats were subjected to RFA of the left median liver lobe (approximately 28.5% of the liver volume) after midline laparotomy. At 30 min, 24 h, 48 h, 72 h or 1 wk postoperatively, (1) blood samples were collected from the portal and systemic circulation for assessment of endotoxin concentration, (2) tissue specimens were excised from mesenteric lymph nodes, non-ablated liver, pancreas, spleen, kidneys, and lungs for bacterial culture, and (3) segments of terminal ileum were excised for histopathologic examination, morphometric analysis, and apoptotic and mitotic rate estimation. At 1 and 48 h, ileal mucosa was collected for oxidative state assessment on the basis of glutathione to glutathione disulfate (GSH/GSSG) ratio. RESULTS Endotoxin levels were increased in both the portal and systemic circulation. Intestinal bacteria were isolated from all the organs at all time points. Ileal mucosa became gradually atrophic, with a decrease in villous height and density. There was an increase of crypt apoptotic rate, a decrease of GSH/GSSG ratio, while there were only mild signs of inflammation. CONCLUSIONS Large volume liver RFA in the rat resulted to endotoxemia and translocation of intestinal bacteria to proximal and distal to the intestine organs at both the early and late post-RFA periods. The intestinal mucosa barrier was disrupted as suggested by ileal mucosal atrophy, increased crypt apoptosis, and induction of oxidative stress.

Pringle maneuver exacerbates systemic inflammatory response and multiple-organ injury induced by extended liver radiofrequency ablation

Aim: To assess the systemic inflammatory response (SIR) and the multi-organ damage after large-volume liver radiofrequency ablation (RFA) with or without concurrent Pringle maneuver. Methods: Wistar rats were subjected to 30% liver RFA (group RFA), liver RFA under 30-min Pringle maneuver (group RFA + P), Pringle only (group P) or sham operation (group S). Serum levels of interleukin-1α (IL-1α), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), serum biochemical profile, multiple-organ pathology and the activity of nuclear factor-κB (NF-κB) in the liver were assessed post-operatively. Results: The levels of IL-6 and TNF-α were increased from 1h up to 1w and 6h, respectively, in both RFA groups, while IL-6 was only mildly increased at 3 h in group P. IL-6 was higher in group RFA + P compared to group RFA. Serum biochemical profile was altered more intensely in group RFA + P compared to RFA. There was tissue injury in the non-ablated liver portion as well as in adjacent and remote organs with lesions being more severe in group RFA + P. At 1 h, NF-κB was equally activated in all study groups. Conclusions: Extended liver RFA causes SIR and multi-organ injury, which are exacerbated when a concurrent Pringle maneuver is applied.

Impaired liver regeneration following partial hepatectomy using the Pringle maneuver: Protective effect of mesna

Background and Aim:  We investigated the role of the prophylactic administration of the antioxidant 2‐mercaptoethane sulfonate (mesna) on the hepatocyte‐regenerating capacity following partial hepatectomy (PH) with concurrent Pringle maneuver.

Mesna Preserves Hepatocyte Regenerating Capacity Following Liver Radiofrequency Ablation Under Pringle Maneuver

BACKGROUND The objectives of the present study were to test the hypothesis that hepatocyte regenerating activity induced by radiofrequency ablation (RFA) of the liver is attenuated when performed under Pringle maneuver, and to investigate the potentially protective effect of mesna prophylactic administration. MATERIALS AND METHODS Wistar rats were subjected to liver RFA (group RFA), RFA plus Pringle maneuver for 30 min (group RFA+P), RFA plus Pringle plus mesna (400mg/kg, per os, 3h prior to operation) (group RFA+P+M), Pringle only (group P), or sham operation (group S) after midline laparotomy. At 1h, liver oxidative state (glutathione to glutathione disulfide ratio-GSH/GSSG) and nuclear factor κB (NF-κB) activity were assessed in liver specimens. At 1, 3, and 6h, the levels of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) were measured in blood serum. At 24h, 48 h, 1 wk, and 3 wk, the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured in blood serum and the histopathologic profile and hepatocyte mitotic activity were assessed in liver specimens. RESULTS Mitotic activity was low but sustained in groups RFA and RFA+P+M, more intense in group P, while suppressed in group RFA+P. Histopathologic profile was deteriorated with lesions being more intense in group RFA+P but significantly less severe in group RFA+P+M. Oxidative stress was equally induced in all experimental groups. NF-κB was activated in groups RFA, RFA+P, and P, but not in group RFA+P+M. IL-6 and TNF-α serum levels were increased; the levels were significantly higher in group RFA+P, while lower in group RFA+P+M. Serum transaminases levels were increased during the first 48 h. CONCLUSIONS Hepatocyte regenerating activity is suppressed following liver RFA under Pringle maneuver. Prophylactic administration of mesna preserves hepatocyte regenerating capacity by attenuating acute inflammatory response and minimizing hepatic tissue injury in the non-ablated liver parenchyma.

The Role of Eugenol in the Prevention of Acute Pancreatitis-Induced Acute Kidney Injury: Experimental Study.

Aim. Acute pancreatitis is an inflammatory intra-abdominal disease, which takes a severe form in 15–20% of patients and can result in high mortality especially when complicated by acute renal failure. The aim of this study is to assess the possible reduction in the extent of acute kidney injury after administration of eugenol in an experimental model of acute pancreatitis. Materials and Methods. 106 male Wistar rats weighing 220–350 g were divided into 3 groups: (1) Sham, with sham surgery; (2) Control, with induction of acute pancreatitis, through ligation of the biliopancreatic duct; and (3) Eugenol, with induction of acute pancreatitis and eugenol administration at a dose of 15 mg/kg. Serum urea and creatinine, histopathological changes, TNF-α, IL-6, and MPO activity in the kidneys were evaluated at predetermined time intervals. Results. The group that was administered eugenol showed milder histopathological changes than the Control group, TNF-α activity was milder in the Eugenol group, and there was no difference in activity for MPO and IL-6. Serum urea and creatinine levels were lower in the Eugenol group than in the Control group. Conclusions. Eugenol administration was protective for the kidneys in an experimental model of acute pancreatitis in rats.

Attenuation of Propofol Tolerance Conferred by Remifentanil Co-Administration Does Not Reduce Propofol Toxicity in Rabbits Under Prolonged Mechanical Ventilation

BACKGROUND Prolonged sedation with propofol at high doses may lead to fatal multi-organ dysfunction, know as propofol infusion syndrome. We tested the hypothesis that propofol plus remifentanil co-administration attenuates propofol tolerance to its sedative effect and assessed if such an effect has an impact on propofol toxicity in rabbits under prolonged mechanical ventilation. MATERIALS AND METHODS Eighteen healthy male rabbits were mechanically ventilated and received propofol (group P, n = 6), propofol plus remifentanil (group PR, n = 6), or remifentanil plus sevoflurane (group RS, n = 6) in order to be kept under sedation (group P) or sedation/analgesia (groups PR and RS) for up to 48 h. Initial propofol and remifentanil infusion rates (IRs) were adjusted, if needed, to maintain the desired level of sedation and analgesia, respectively (groups P and PR). In group RS, remifentanil was infused at IRs equivalent to those of group PR. Propofol IRs were recorded, propofol concentrations were measured in the arterial plasma, and blood biochemical parameters and organ histopathology were assessed. RESULTS Animals survived for 29-36 h in group P and 22-38 h in group PR (100% mortality rate). Tolerance was developed to propofols sedative effect. The onset of tolerance was delayed and its magnitude was decreased in group PR compared with group P. Propofol was accumulated in the systemic circulation. Propofol clearance rate was gradually decreased. Arterial lactate, and serum aspartate aminotransferase (AST), lactate dehydrogenase (LDH), bilirubin, cholesterol, triglycerides, and creatine kinase (CK) levels were increased. The heart, lungs, liver, gallbladder, kidneys, urinary bladder, and skeletal muscles were seriously injured in groups P and PR. In group RS, mortality was 0%, while there was only mild injury of the lungs, liver, gallbladder, kidneys, and urinary bladder. CONCLUSIONS Although propofol tolerance is attenuated in propofol plus remifentanil receiving rabbits under prolonged mechanical ventilation, fatal multi-organ injury occurs resembling human propofol infusion syndrome.

Expression of Fas (CD95/APO-1) and Fas Ligand (FasL) in Experimentally-Induced Acute Pancreatitis

ABSTRACT Introduction: Acinar cell death is a crucial event in acute pancreatitis (AP) and may occur either by apoptosis or necrosis. The aim of this study was to investigate the expression of the apoptosis associated proteins Fas and FasL in experimentally induced severe AP. Methods: AP was induced in 30 rats by injecting 0.2 ml of 4.5% sodium taurocholate solution into the biliopancreatic duct. Sham operated animals (n = 30) and 10 normal controls were used for comparisons. Animals were killed at 6, 12, 24, 48, 72 hr and 1 week after operation (five animals at each time point) and both serum and pancreatic tissue were obtained. The severity of AP was graded by morphological evaluation and by measuring serum amylase levels. Acinar cell apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assay. Tissue expressions of Fas and FasL were evaluated by immunohistochemistry. Results: Sodium taurocholate injection resulted in severe acute necrotizing pancreatitis as early as six hr after taurocholate infusion with gradually increasing severity and a peak at 72 hr, and a significant increase of serum amylase at 6 and 12 hr. Apoptotic acinar cells were observed between 48 and 72 hr. The expression of both Fas and FasL in pancreatic tissue was induced in comparison with normal controls. Fas expression in AP was higher and statistically significant at 24 hr whereas FasL expression was consistently lower with a statistical significance observed at 12 hr when compared to sham-operated animals suggesting Fas upregulation and FasL downregulation in this model of AP. Conclusions: Induction and sequential changes in the expressions of Fas and FasL occur during taurocholate induced severe AP in rats and their temporal modulation might associate with acinar cell death by apoptosis.