Effects of amrinone on hepatic ischemia-reperfusion injury in rats

Preoperative transarterial chemoembolization (TACE) + liver resection versus upfront liver resection for large hepatocellular carcinoma (≥5 cm): a systematic review and meta-analysis

BACKGROUND

Hepatocellular carcinoma (HCC) accounts for majority of primary liver cancer. Use of preoperative neoadjuvant transarterial chemoembolization (PN-TACE) may result in tumor shrinkage and improve resectability. This study aims to summarize the outcomes of PN-TACE versus upfront liver resection (Up-LR) in large HCC (≥5 cm).

METHODS

PubMed, Embase, The Cochrane Library, and Scopus were systematically searched till September 2022 for studies comparing PN-TACE versus Up-LR. The primary study outcomes were overall survival (OS), disease-free survival (DFS), and recurrence. Our secondary outcomes were postoperative morbidity and mortality.

RESULTS

There were 12 studies with 15 data sets including 3960 patients (PN-TACE n = 2447, Up-LR n = 1513). Majority (89.5%, n = 1250/1397) of patients had Child's A liver cirrhosis. Incidence of Child's B cirrhosis was higher in PN-TACE compared to Up-LR (Odds ratio (OR) 1.69, 95% CI: 1.18, 2.41, p = 0.004). Pooled hazard ratio (HR) for OS showed no significant difference between PN-TACE and Up-LR (HR 0.87, 95% CI: 0.64, 1.18, p = 0.37), but DFS was superior in PN-TACE (HR 0.79, 95% CI: 0.63, 0.99, p = 0.04). Subgroup analysis based on study design failed to show any significant effect in randomized controlled trials (n = 2/15 data sets). However, operating time (mean difference (MD) 31.94 min, 95% CI: 2.42, 61.45, p = 0.03) and blood loss (MD 190.93 ml, 95% CI: 10.22, 317.65, p = 0.04) were higher in PN-TACE. Intrahepatic and extrahepatic recurrence, post-operative morbidity and in-hospital mortality were comparable between PN-TACE and Up-LR.

CONCLUSION

In retrospective studies, PN-TACE resulted in superior DFS compared to Up-LR. However, this may be confounded by selection bias.

The Expanding Role of Pyridine and Dihydropyridine Scaffolds in Drug Design

Pyridine-based ring systems are one of the most extensively used heterocycles in the field of drug design, primarily due to their profound effect on pharmacological activity, which has led to the discovery of numerous broad-spectrum therapeutic agents. In the US FDA database, there are 95 approved pharmaceuticals that stem from pyridine or dihydropyridine, including isoniazid and ethionamide (tuberculosis), delavirdine (HIV/AIDS), abiraterone acetate (prostate cancer), tacrine (Alzheimer's), ciclopirox (ringworm and athlete's foot), crizotinib (cancer), nifedipine (Raynaud's syndrome and premature birth), piroxicam (NSAID for arthritis), nilvadipine (hypertension), roflumilast (COPD), pyridostigmine (myasthenia gravis), and many more. Their remarkable therapeutic applications have encouraged researchers to prepare a larger number of biologically active compounds decorated with pyridine or dihydropyridine, expandeing the scope of finding a cure for other ailments. It is thus anticipated that myriad new pharmaceuticals containing the two heterocycles will be available in the forthcoming decade. This review examines the prospects of highly potent bioactive molecules to emphasize the advantages of using pyridine and dihydropyridine in drug design. We cover the most recent developments from 2010 to date, highlighting the ever-expanding role of both scaffolds in the field of medicinal chemistry and drug development.

Pretreatment with a Phosphodiesterase-3 Inhibitor, Milrinone, Reduces Hepatic Ischemia-Reperfusion Injury, Minimizing Pericentral Zone-Based Liver and Small Intestinal Injury in Rats

BACKGROUND Severe pericentral zone (zone 3)-based liver injury (LI) may become intractable, with allograft dysfunction after liver transplantation. The phosphodiesterase-3 inhibitor, milrinone, has been reported to attenuate hepatic ischemia-reperfusion injury (IRI). This study clarified how hepatic IRI involved zone 3-based LI, in which zone milrinone was effective, and whether milrinone could improve small intestinal injury (SII) with hepatic IRI. MATERIAL AND METHODS Rats were divided into sham, ischemia-reperfusion (IR), or IR+milrinone groups (n=13 per group). Milrinone was administered intraportally via intrasplenic injection, and whole hepatic ischemia was induced for 30 min. Five hours after reperfusion, serum chemistry and histopathological findings were compared. Expression of CD34 for the detection of altered sinusoidal endothelium as sinusoidal capillarization and cleaved caspase-3 as an apoptosis marker were analyzed via immunohistochemistry. Survival rates were examined after 45 min of whole hepatic ischemia. RESULTS Serum aspartate aminotransferase and direct bilirubin levels were significantly decreased in the IR+milrinone group compared with those of the IR group. The degree of LI, sinusoidal capillarization and apoptosis at zone 3 in the IR group was significantly increased compared with those at the periportal zone (zone 1). These findings at zone 3 in the IR group were improved in the IR+milrinone group. SII with villus congestion and apoptosis in the IR group was significantly attenuated in the IR+milrinone group. The 7-day survival rate was significantly elevated in the IR+milrinone group as compared with that of the IR group. CONCLUSIONS A hepatic IRI model caused zone 3-based LI and SII, which were attenuated by intraportal administration of milrinone.

Phase I clinical trial of olprinone in liver surgery

PURPOSE

Post-hepatectomy liver failure is one of the most serious complications liver surgeons must overcome. We previously examined olprinone, a selective phosphodiesterase III inhibitor, and demonstrated its hepatoprotective effects in rats and pigs. We herein report the results of a phase I clinical trial of olprinone in liver surgery (UMIN000004975).

METHODS

Twenty-three patients who underwent hepatectomy between 2011 and 2015 were prospectively registered. In the first 6 cases, olprinone (0.1 μg/kg/min) was administered for 24 h from the start of surgery. In the remaining 17 cases, olprinone (0.05 μg/kg/min) was administered from the start of surgery until just before the transection of the liver parenchyma. The primary endpoint was safety, and the secondary endpoint was efficacy. For the evaluation of efficacy, the incidence of post-hepatectomy liver failure in 20 hepatocellular carcinoma patients was externally compared with 20 propensity score-matched patients.

RESULTS

No intraoperative side effects were observed, and the morbidity rates in the analyzed cohorts were acceptable. The rate of post-hepatectomy liver failure frequency tended to be lower in the olprinone group.

CONCLUSIONS

The safety of olprinone in liver surgery was confirmed. The efficacy of olprinone will be re-evaluated in clinical trials.

Hepatoprotective effect by pretreatment with olprinone in a swine partial hepatectomy model

Excessive portal flow to a small remnant liver or small-for-size graft is a primary factor of small-for-size syndrome. We demonstrated that olprinone (OLP), a phosphodiesterase III inhibitor, had a hepatoprotective effect in a rat extended hepatectomy model and a small-for-size liver transplantation model through a modification of the portal venous pressure (PVP). To identify the appropriate dose and duration of treatment for clinical applications, we conducted experiments with a swine partial hepatectomy model. Twenty microminipigs were divided into 4 groups that received the following treatments: (A) saline (control group), (B) OLP at 0.3 μg/kg/minute (preoperative and postoperative administration), (C) OLP at 0.1 μg/kg/minute (preoperative administration), and (D) OLP at 0.3 μg/kg/minute (preoperative administration). The pigs underwent 70% partial hepatectomy. Hemodynamic changes, including changes in PVP, were examined. Liver biopsy was performed 1 and 3 hours after hepatectomy. Blood samples were collected until postoperative day 7 (POD7). In comparison with group A, PVP elevations, periportal edema, and sinusoidal hemorrhaging were attenuated after left Glisson's ligation in groups C and D. Pretreatment with OLP in groups C and D preserved the microstructure of sinusoids and improved the prothrombin activity 1 and 3 hours after hepatectomy. These animals showed better recovery of the remnant liver volume and the plasma disappearance rate of indocyanine green on POD7. In contrast, group B showed exacerbation of liver damage. Measurements of the serum OLP concentration showed that 10 ng/mL OLP was appropriate for a hepatoprotective effect. In conclusion, pretreatment with OLP shows hepatoprotective effects in a swine partial hepatectomy model. OLP may have the potential to ameliorate patients' outcomes after hepatectomy or liver transplantation.

Reversal of oxidant-mediated biochemical injury and prompt functional recovery after prolonged single-dose crystalloid cardioplegic arrest in the infantile piglet heart by terminal warm-blood cardioplegia supplemented with phosphodiesterase III inhibitor

PURPOSE

The benefit of terminal blood cardioplegia (TWBCP) is insufficient after prolonged ischemia associated with inevitable oxidant-mediated injury by this modality alone. We tested the effects of TWBCP supplemented with high-dose olprinone, which is a phosphodiesterase III inhibitor, a clinically available compound with the potential to reduce oxidant stress and calcium overload. We evaluated the effects with respect to avoiding oxidant-mediated myocardial reperfusion injury and prompt functional recovery after prolonged single-dose crystalloid cardioplegic arrest in a infantile piglet cardiopulmonary bypass (CPB) model.

METHODS

Fifteen piglets were subjected to 90 min of cardioplegic arrest on CPB, followed by 30 min of reperfusion. In group I, uncontrolled reperfusion was applied without receiving TWBCP; in group II, TWBCP was given; in group III, TWBCP was supplemented with olprinone (3 μg/ml). Myocardial performance was evaluated before and after CPB by a left ventricular (LV) function curve and pressure-volume loop analyses. Biochemical injury was determined by measurements of troponin-T and lipid peroxide (LPO) in coronary sinus blood.

RESULTS

Group III showed significant LV performance recovery (group I, 26.5% ± 5.1%; group II, 42.9% ± 10.8%; group III, 81.9% ± 24.5%, P < 0.01 vs. groups I and II), associated with significant reduction of troponin-T and LPO at the reperfusion phase. No piglets in group III needed electrical cardioversion.

CONCLUSION

We concluded that TWBCP with olprinone reduces myocardial reperfusion injury by reducing oxidant-mediated lipid peroxidation, and it accelerates prompt and persistent LV functional recovery with suppression of reperfusion arrhythmia.

Olprinone attenuates excessive shear stress through up-regulation of endothelial nitric oxide synthase in a rat excessive hepatectomy model

After extended hepatectomy, excessive shear stress in the remnant liver causes postoperative liver failure. Olprinone (OLP), a selective phosphodiesterase inhibitor, has been reported to improve microcirculation and attenuate inflammation. The aim of this study was to investigate the effects of OLP on shear stress in rats with an excessive hepatectomy (EHx) model. In this study, EHx comprised 90% hepatectomy with ligation of the left and right Glisson's sheaths in Lewis rats. OLP or saline was intraperitoneally administered with an osmotic pump 48 hours before EHx. To evaluate the shear stress, we measured the portal vein (PV) pressure. We also assessed sinusoidal endothelial cell injury by immunohistochemistry and electron microscopy. Furthermore, we assessed apoptosis in the liver with the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method. Treatment with OLP up-regulated hepatic endothelial nitric oxide synthase (eNOS) expression. The increase in the PV pressure due to Glisson's sheath ligation was attenuated in OLP-treated rats during a 30-minute period after ligation. Treatment with OLP preserved sinusoidal endothelial cells and reduced apoptosis in the remnant liver. The probability of survival in the OLP-treated rats was significantly better than that in the controls (33.3% versus 13.3%). Furthermore, the postoperative eNOS activity in the OLP-treated rats was higher than that in the controls. The administration of Nω-nitro-l-arginine methyl ester to OLP-treated rats eliminated the effects of OLP on PV pressure and survival after EHx. Therefore, we concluded that OLP attenuates excessive shear stress through the up-regulation of eNOS and improves the survival rate after EHx.

Abnormal modulation of cell protective systems in response to ischemic/reperfusion injury is important in the development of mouse sickle cell hepatopathy

BACKGROUND

Sickle cell disease, a genetic red cell disorder inherited in an autosomal recessive manner, occurs throughout the world. Hepatic dysfunction and liver damage may be present in sickle cell disease, but the pathogenesis of these conditions is only partially understood.

DESIGN AND METHODS

Transgenic mice with sickle cell disease (SAD mice) and wild-type mice were exposed to an ischemic/reperfusion stress. The following parameters were evaluated: hematologic profile, transaminase and bilirubin levels, liver histopathology, and mRNA levels of nuclear factor-κB p65, endothelial nitric oxide synthase, inducible nitric oxide synthase, heme oxygenase-1 and phosphodiesterase-1, -2, -3, and -4 genes in hepatocytes obtained by laser-capture microdissection. Immunoblotting was used to analyze the expression of the following proteins: nuclear factor-κB p65 and phospho-nuclear factor-κB p65, heme oxygenase-1, biliverdin reductase, heat shock protein-70, heat shock protein-27 and peroxiredoxin-6. A subgroup of SAD mice was treated with the phosphodiesterase-4 inhibitor rolipram (30 mg/Kg/day by gavage) during the ischemic/reperfusion protocol.

RESULTS

In SAD mice the ischemic/reperfusion stress induced liver damage compatible with sickle cell disease hepatopathy, which was associated with: (i) lack of hypoxia-induced nuclear factor-κB p65 activation; (ii) imbalance in the endothelial/inducible nitric oxide synthase response to ischemic/reperfusion stress; (iii) lack of hypoxia-induced increased expression of heme oxygenase-1/biliverdin reductase paralleled by a compensatory increased expression of heat shock proteins 70 and 27 and peroxiredoxin-6; and (iv) up-regulation of the phosphodiesterase-1, -2, -3, and -4 genes. In SAD mice the phosphodiesterase-4 inhibitor rolipram attenuated the ischemic/reperfusion-related microcirculatory dysfunction, reduced the inflammatory cell infiltration and induced the heme oxygenase-1/biliverdin reductase cytoprotective systems.

CONCLUSIONS

In SAD mice, sickle cell hepatopathy is associated with perturbed nuclear factor-κB p65 signaling with an imbalance of endothelial/inducible nitric oxide synthase levels, lack of heme oxygenase-1/biliverdin reductase expression and up-regulation of two novel cytoprotective systems: heat shock protein-27 and peroxiredoxin-6.

Effect of olprinone, a phosphodiesterase III inhibitor, on hepatic ischemia-reperfusion injury in rats

I/R injury is the main cause for hepatic dysfunction and failure after liver transplantation and liver resection. Therefore, reduction of I/R injury is the most important goal to improve the outcome of these procedures. Olprinone is a newly developed selective phosphodiesterase III inhibitor, which has been reported to ameliorate renal I/R injury in rats. However, no clear evidence for the actions of olprinone on inflammatory response after hepatic I/R injury has been disclosed thus far. Our study was designed to evaluate the action of olprinone on the hepatic I/R injury in rats. Olprinone increased the cyclic adenosine monophosphate level in injured liver tissue and ameliorated the liver injury after hepatic I/R. Moreover, olprinone suppressed the activation of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and nuclear factor-kappaB, cytokine production (TNF-alpha, IL-6, and cytokine-induced neutrophil chemoattractant factor 1), and intercellular adhesion molecule 1 expression in liver after hepatic I/R. These observations suggest that olprinone protects liver against I/R injury via the elevation of cyclic adenosine monophosphate level and suppression of intercellular adhesion molecule 1 expression and cytokine production (TNF-alpha, IL-6, and cytokine-induced neutrophil chemoattractant factor 1), possibly by interfering with the signaling pathways of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and nuclear factor-kappaB in rats.

The role of phosphodiesterase 3 in endotoxin-induced acute kidney injury

Background

Acute kidney injury frequently accompanies sepsis. Endotoxin is known to reduce tissue levels of cAMP and low levels of cAMP have been associated with renal injury. We, therefore, hypothesized that endotoxin induced renal injury by activating phosphodiesterase 3 (PDE3) which metabolizes cAMP and that amrinone an inhibitor of PDE3 would prevent the renal injury.

Methods

Animals were divided into three groups (n = 7/group): 1) Control (0.9% NaCl infusion without LPS); 2) LPS (0.9% NaCl infusion with LPS); 3) Amrinone+LPS (Amrinone infusion with LPS). Either lipopolysaccharide (LPS) or vehicle was injected via the jugular vein and the rats followed for 3 hours. We explored the expression of PDE3 isoenzymes and the concentrations of cAMP in the tissue.

Results

The PDE3B gene but not PDE3A was upregulated in the kidney of LPS group. Immunohistochemistry also showed that PDE3B was expressed in the distal tubule in the controls and LPS caused PDE3B expression in the proximal as well. However, PDE3A was not expressed in the kidney either in the control or LPS treated groups. Tissue level of cAMP was decreased after LPS and was associated with an increase in blood urea nitrogen, creatinine, ultrastructural proximal tubular changes, and expression of inducible nitric oxide synthase (iNOS) in the endotoxemic kidney. In septic animals the phosphodiesterase 3 inhibitor, amrinone, preserved the tissue cAMP level, renal structural changes, and attenuated the increased blood urea nitrogen, creatinine, and iNOS expression in the kidney.

Conclusion

These findings suggest a significant role for PDE3B as an important mediator of LPS-induced acute kidney injury.

Effects of amrinone in an experimental model of hepatic ischemia-reperfusion injury

BACKGROUND

During some surgical interventions, temporary occlusion of the hepatic blood supply may cause ischemia-reperfusion (IR) injury. Recent studies suggest that type 3 phosphodiesterase inhibitors may have a beneficial effect on liver IR injury. The aim of this study was to investigate whether amrinone, a type 3 phosphodiesterase inhibitor, could have a protective effect on liver having experimental liver IR injury.

MATERIALS AND METHODS

Sixty Wistar albino rats were randomly divided into three groups. The IR and amrinone groups were subjected to 1 h total hepatic ischemia, followed by 2 h of reperfusion. The sham group underwent midline laparotomy only. Amrinone 10 microg/kg/min was infused to the amrinone group during the 3 h of the IR period. Histopathological examination, biochemical liver function, and liver adenosine triphosphate concentration after reperfusion and survival rate on the seventh day after the IR insult were recorded.

RESULTS

Serum aspartate aminotransferase, alanine aminotransferase, lactic dehydrogenase levels, and histological damage scores in the amrinone and IR groups were significantly higher compared with the sham group (P < 0.01). However, all of these values were significantly lower in the amrinone group than in the IR group (P < 0.05). Liver adenosine triphosphate levels and the rat survival rate in the amrinone and IR groups were significantly lower than those in the sham group (P < 0.01). However, these values were significantly higher in the amrinone group compared to those in the IR group (P < 0.01).

CONCLUSIONS

These results suggest that amrinone plays a significant role in the protection of liver against IR injury and that this treatment may be a novel pharmacological agent for safe and efficient liver surgery.

Dynamic changes of post-ischemic hepatic microcirculation improved by a pre-treatment of phosphodiesterase-3 inhibitor, milrinone

BACKGROUND

Phosphodiesterase-3 inhibition has been shown to attenuate hepatic warm ischemia-reperfusion injury. The aim of this study was to investigate the effect of milrinone, phosphodiesterase-3 inhibitor, on post-ischemic microcirculation of rat livers by intravital microscopy.

MATERIALS AND METHODS

Male Wistar rats were randomly assigned to three groups; group A, milrinone pre-treatment; group B, ischemic pre-conditioning; and group C, no pre-treatment. All animals underwent a 60-min warm ischemia of the left lateral liver lobe. Microvascular perfusion and leukocyte-endothelial interaction were observed by intravital videomicroscopy. Hepatocellular viability and cellular damage were quantified by adenosine triphosphate tissue concentration as well as alanine aminotransferase and lactate dehydrogenase blood levels, respectively.

RESULTS

In groups A and B, cyclic AMP hepatic tissue concentration was elevated significantly. After reperfusion, microvascular perfusion in hepatic sinusoids was significantly better maintained, and the number of adherent leukocytes was reduced in sinusoids and in post-sinusoidal venules in these rats. Serum transaminase blood levels were suppressed significantly in these groups compared with controls.

CONCLUSION

The demonstrated improvement of hepatic microcirculation is certainly derived from milrinone induced cell protection in ischemia reperfusion of the liver. This effect is outlined by improved energy status and reduced liver enzyme liberation and mimics the effect of ischemic pre-conditioning.

Kupffer cell-mediated downregulation of hepatic transporter expression in rat hepatic ischemia-reperfusion

BACKGROUND

Hepatic ischemia-reperfusion (IR) injury is frequently followed by cholestatic liver disease. Cytokines released by Kupffer cells following hepatic IR injury may subsequently regulate hepatic transporter expression. The purpose of this study was to determine whether hepatic IR injury and the resultant Kupffer cell activation alters hepatic transporter expression.

METHODS

Rats were subjected to 60 minutes of partial hepatic ischemia followed by 0, 3, 6, 24, or 48 hours of reperfusion. After IR surgery, the following were determined: 1) serum bilirubin and bile acid levels; 2) serum levels of cytokines, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL6; 3) expression of several hepatic transporters; and 4) nuclear protein levels of hepatocyte nuclear factor (HNF)-1alpha and retinoid X receptor (RXR)-alpha to investigate whether altered expression of hepatic transporters following IR is associated with decreases in these transcription factors.

RESULTS

After reperfusion: 1) serum bilirubin and bile acids increased; 2) levels of all three cytokines increased; 3) mRNA expression of hepatic transporters organic anion transporting polypeptide (Oatp) 1a1, Oatp1a4, Oatp1b2, sodium taurocholate cotransporting polypeptide, multidrug resistance-associated protein (Mdr) 2, and bile salt export pump decreased, whereas Mdr1b expression increased; and 4) nuclear protein levels of HNF1alpha decreased, whereas RXRalpha was not altered. Pretreatment with gadolinium chloride to deplete Kupffer cells before IR: 1) blocked the increase in serum bile acids, 2) attenuated TNFalpha but not IL1beta/IL6 levels, 3) inhibited the altered hepatic transporter expression, and 4) blocked the decrease in HNF1alpha nuclear protein levels.

CONCLUSIONS

These results suggest that alterations in hepatic transporter expression during IR occur through Kupffer cell-mediated events, possibly involving a decrease in nuclear HNF1alpha.

The Effect of Amrinone on Liver Regeneration in Experimental Hepatic Resection Model1

BACKGROUND

The phosphodiesterase inhibitors (PDEIs) have been proposed to improve hepatic reperfusion injury and hepatosplanchnic circulation, but the effects of these agents on liver regeneration have not been investigated thoroughly. The aim of this study was to investigate the effect of amrinone, a PDEI, on liver regeneration in rats.

MATERIALS AND METHODS

Sixty rats were divided into two groups, control and amrinone. Each group was then divided into three groups (n=10). An infusion of amrinone to the study group and of 0.9% NaCl to the control group was performed. Seventy percent liver resection was performed to the rats during the first hour of infusion. The infusion was maintained for 17 h after resection. A total of 18 h infusion was performed. Rats were allowed to survive for 24, 48, and 72 h, and then they were sacrificed. Biochemical, morphological, hematological, and histopathologic measurements and assessments were performed.

RESULTS

There were statistically significant differences between the amrinone and control groups in alkaline phosphatase and relative liver weights at 24, 48, and 72 h (P<0.05). There also were statistically significant differences between the groups in AST, bilirubin, and albumine levels at 24 h, ALT and prothrombine time levels at 48 h, and aspartate aminotransferase and alanine aminotransferase levels at 72 h (P<0.05). Hepatic ATP levels, mitotic index, and proliferating cell nuclear antigen labeling index were significantly higher in amrinone group compared with control group at all three time intervals (P<0.05).

CONCLUSIONS

Amrinone improves both morphological and functional liver regeneration after liver resection.

Olprinone reduces ischemia/reperfusion-induced acute renal injury in rats through enhancement of cAMP

Activated leukocytes are implicated in development of ischemia/reperfusion (I/R)-induced organ injuries. Phosphodiesterase 3 inhibitors have anti-inflammatory effects by preventing cyclic adenosine monophosphate (cAMP) degradation. We examined the effects of olprinone, a specific phosphodiesterase 3 inhibitor, on I/R-induced acute renal injury model in rats. Forty-five minute renal I/R was induced in uni-nephrectomized rats. Rats were divided into a vehicle group, an olprinone group, and a dibutyril (DB) cAMP group. Olprinone (0.2 microg/kg/minute) infusion began 30 min after reperfusion and continued for 3 h. DBcAMP (5 mg/kg), a stable analog of cAMP, was intraperitoneally administered 5 min after reperfusion to clarify the effect of cAMP in our model. Olprinone reduced the I/R-induced increases in serum levels of blood urea nitrogen and creatinine, and improved histological changes, including acute tubular necrosis in the outer medulla. Hemodynamic status was not affected by olprinone. I/R-induced a decrease in renal tissue blood flow, an increase in renal vascular permeability, and an enhancement of leukocyte activation, reflected by renal tissue levels of myeloperoxidase activity, and the tissue levels of cytokine-induced neutrophil chemoattractant (an equivalent of human interleukin 8) and tumor necrosis factor-alpha were all significantly decreased by olprinone. Olprinone also increased the renal tissue and plasma levels of cAMP in rats subjected to renal I/R. DBcAMP showed similar effects. Our results indicated that olprinone reduced the I/R-induced acute renal injury, probably by inhibiting leukocyte activation. The effects of olprinone could be explained through its action on cAMP levels.

Ischemic preconditioning versus intermittent vascular inflow control during major liver resection in pigs

Ischemic preconditioning (IPC) and intermittent vascular control (IVC) have been shown to reduce the number of ischemia/reperfusion injuries during liver resections with the Pringle maneuver. Our study aimed to compare the beneficial effect of these two modalities in relation to the duration of normothermic liver ischemia. A group of 24 Landrace pigs with a mean body weight of 25 to 30 kg were subjected to extended liver resection of more than 65%. Although, 12 animals underwent IPC (10 minutes of ischemia and 10 minutes of reperfusion), and subsequently the Pringle maneuver was applied for 90 minutes (n= 6) or 120 minutes (n= 6). Another 12 animals underwent liver resection by IVC (20 minutes of ischemia alternated with 5 minutes of reperfusion) for 60 minutes (n = 6) or 120 minutes (n = 6) of inflow vascular control. At 90 minutes of liver ischemia, the IPC group demonstrated lower levels of asportate aminotransferase (AST) (173 +/- 53 vs. 265 +/- 106 IU; p =0.089) and malondialdehyde (MDA) (2.60 +/- 1.03 vs. 5.33 +/- 2.25 micromol/L; p =0.022) and higher liver tissue cAMP (200 +/- 42 vs. 146 +/- 40 pmol/g wet wt, p = 0.04) compared to the IVC group. However, no pathologic differences were observed between the two groups. By contrast, at 120 minutes of liver ischemia, IVC proved to be more beneficial, reflected by lower levels of AST (448 +/- 135 vs. 857 +/- 268 IU; p = 0.006) and MDA (8.33 +/- 1.75 vs. 12.7 +/- 4.31 micromol/L; (p = 0.045), a higher cAMP level (127 +/- 10 vs. 97 +/- 31 pmol/g wet wt p = 0.045), and eventually less cellular necrosis (necrosis score 1.66 +/- 0.51 vs. 2.85 +/- 1.16; p = 0.04) compared to the IPC group. It appears that IPC should be employed when liver ischemia is anticipated to last less than 90 minutes, followed by IVC when the liver ischemia is expected to last 120 minutes.

Attenuation of ischemic injury by N-acetylcysteine preconditioning of the liver

BACKGROUND

Numerous previous studies have established the hepatoprotective properties of N-acetylcysteine (NAC). The present study was designed to investigate the effects of NAC on a warm hepatic ischemia-reperfusion rat model with a focus on the role of cAMP.

MATERIALS AND METHODS

Fifty-six male Wistar rats were allocated randomly into the control group (n = 28) or the study group (group NAC, n = 28). Group NAC animals received an intravenous bolus dose of 0.3 mg/g NAC, whereas control animals were given an equal volume of normal saline. Subsequently, 60-min partial liver ischemia was induced by occlusion of blood inflow to the left and middle liver lobes. Aspartate aminotransferase, alanine aminotransferase, and alpha-glutathione S-transferase levels, platelet aggregation, and ischemic tissue cyclic adenosine 5-monophosphate (cAMP) levels were examined at 30, 60, and 120 min after reperfusion. Parts of the ischemic liver were sampled at the same time-points. Measurements were obtained from seven animals at each time point.

RESULTS

The administration of NAC resulted in lower levels of aspartate aminotransferase, alanine aminotransferase, and alpha-glutathione S-transferase, decreased platelet aggregation, and increased levels of ischemic tissue cAMP at all time points after reperfusion. Histologically, fewer necrotic changes were observed in the NAC group at 60 and 120 min after reperfusion. All differences were statistically significant (P < 0.05).

CONCLUSIONS

In the present study, NAC seems to attenuate hepatic ischemia-reperfusion damage, as demonstrated by liver function tests and liver histology. The effects of NAC appear to be mediated by the decrease in platelet aggregation and increase in the levels of cAMP observed in ischemic liver tissue.

Effect of amrinone on mucosal permeability in experimental intestinal ischaemia/reperfusion injury

BACKGROUND

The preventive effect of amrinone on ischaemia/reperfusion (I/R) injury has been shown in the medical literature. The purpose of the present study was to investigate the preventive effect of amrinone on I/R injury of the small bowel of the rat.

METHODS

Thirty-two Wistar albino rats (140-180 g) were divided into four groups (n = 8). In all groups except the sham group the superior mesenteric artery was clamped for 30 min. At the beginning of reperfusion, 1 mL of 2405 Bq/mL 51Cr-ethylenediamine tetra-acetic acid (EDTA) was administered into the prepared ileal segment. Following 30 min of reperfusion, 1 mL of blood was obtained from the portal vein. After the rats were killed, the small intestine was removed for histopathological studies. A total of 5 mg/kg amrinone was administered to the rats in group 1 before ischaemia and in group 2 before reperfusion, whereas only saline was administered to the rats in the control group. Statistical analysis was carried out with Kruskal-Wallis and chi2 test, P < 0.01 was considered significant.

RESULTS

Both the blood 51Cr-EDTA measurements (mean +/- SD) and mucosal injury grades (MIG) were highest in the control group (3.95 +/- 0.71 c.p.m.; MIG, 3-5) followed by group 2 (0.50 +/- 0.35 c.p.m.; MIG, 1-3), group 1 (0.47 +/- 0.34 c.p.m. MIG, 0-3), and sham group (0.12 +/- 0.05 c.p.m.; MIG, 0). The difference between groups 1 and 2 and the control group were statistically significant (P < 0.01 for each comparison). The results of group 1 and 2 were similar statistically (P > 0.05).

CONCLUSIONS

Amrinone was found to be effective in preventing intestinal I/R injury.

Cell apoptosis and regeneration of hepatocellular carcinoma after transarterial chemoembolization

AIM: To evaluate whether cell apoptosis and regeneration were existed in normal liver cells adjacent to carcinoma after transarterial chemoembolization (TACE).

METHODS: Fifty rabbits with hepatic carcinoma were divided into 5 groups at random: group A (control group), groups B and C (TACE treatment groups), groups D and E (partial hepatectomy groups). There were 10 rabbits in each group. Rabbits in groups B-E were treated by transarterial chemoembolization (TACE) and partial hepatectomy (PH) respectively. The changes of S-phase cell fraction (SPF), proliferation index (PI) and cell apoptosis in the normal liver tissue were determined with flow cytometry (FCM) after operations on the first and third days. We determined the mitosis index (MI) with histo-pathological method and the apoptosis index (AI) with TUNEL method at the same time.

RESULTS: Twenty-four hours after operations, compared with control group, the rabbits in TACE group had much higher index of SPF, PI and MI (MI: t = 4.89, P < 0.001; SPF: t = 5.27, P < 0.001; PI: t = 4.87, P < 0.001). Moreover, the proliferation of liver cells in TACE group was much weaker than that of the cells treated by partial hepatectomy, and the differences were significant (MI: t = 7.02, P < 0.001; SPF: t = 4.06, P < 0.001; PI: t = 2.70, P < 0.05). Seventy-two h after operations, FCM showed a small sub-G1 peak in TACE group and PH group, compared with the control group, but there was no difference between them (t = 0.41, P > 0.05). TACE showed that AI in the treated rabbits was higher than that in control group (t = 3.07, P < 0.05), and there were no differences between TACE group and PH group, either (t = 0.93, P > 0.05).

CONCLUSION: Cell apoptosis and regeneration exist in rabbit liver tissues after TACE in some degree, which may be associated with the selective embolization of iodised oil, chemotherapeutic drug and free radical damage.

Linking inflammation to acute rejection in small-for-size liver allografts: the potential role of early macrophage activation

This study aims to investigate the immunological status of small-for-size liver allografts and possible mechanism that contributes to the accelerated immune response in these allografts. Eight experimental groups were: whole isografts; 40% isografts; whole allografts, no treatment; 40% allografts, no treatment; whole allografts with sodium salicylate intraperitoneal injection, D0-3; 40% allografts with sodium salicylate, D0-3; whole allografts with FK506 intramuscular injection D0-3, and 40% allografts with FK506, D0-3. The 40% allografts survived significantly shorter than whole allografts (p=0.02). At 72 h after reperfusion, a higher number of macrophages infiltrated into the periportal area of small-for-size allografts than whole allografts. Remarkable up-regulation of interleukin-1beta (IL-1beta), interleukin-2 (IL-2), interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) messenger RNA (mRNA) levels were detected in small-for-size allografts within 24 h after reperfusion. Sodium salicylate administration reduced IL-1beta and IFN-gamma mRNA in both small-for-size and whole allografts, but it could decrease IL-2 and IL-10 mRNA levels only in small-for-size allografts. In vitro study revealed that CD80, CD86 and CD11b expression on macrophages was augmented after IL-1beta stimulation, whereas the up-regulation could be blocked by sodium salicylate. In conclusion, early activation of macrophages as a result of graft injury might play an important role in the accelerated acute rejection process in small-for-size allografts.