Liver viability after ischemia-reperfusion

Morphological alterations and redox changes associated with hepatic warm ischemia-reperfusion injury

AIM

To study the effects of warm ischemia-reperfusion (I/R) injury on hepatic morphology at the ultrastructural level and to analyze the expression of the thioredoxin (TRX) and glutaredoxin (GRX) systems.

METHODS

Eleven patients undergoing liver resection were subjected to portal triad clamping (PTC). Liver biopsies were collected at three time points; first prior to PTC (baseline), 20 min after PTC (post-ischemia) and 20 min after reperfusion (post-reperfusion). Electron microscopy and morphometry were used to study and quantify ultrastructural changes, respectively. Additionally, gene expression analysis of TRX and GRX isoforms was performed by quantitative PCR. For further validation of redox protein status, immunogold staining was performed for the isoforms GRX1 and TRX1.

RESULTS

Post-ischemia, a significant loss of the liver sinusoidal endothelial cell (LSEC) lining was observed (P = 0.0003) accompanied by a decrease of hepatocyte microvilli in the space of Disse. Hepatocellular morphology was well preserved apart from the appearance of crystalline mitochondrial inclusions in 7 out of 11 patients. Post-reperfusion biopsies had similar features as post-ischemia with the exception of signs of a reactivation of the LSECs. No changes in the expression of redox-regulatory genes could be observed at mRNA level of the isoforms of the TRX family but immunoelectron microscopy indicated a redistribution of TRX1 within the cell.

CONCLUSION

At the ultrastructural level, the major impact of hepatic warm I/R injury after PTC was borne by the LSECs with detachment and reactivation at ischemia and reperfusion, respectively. Hepatocytes morphology were well preserved. Crystalline inclusions in mitochondria were observed in the hepatocyte after ischemia.

Small-for-size liver graft injury--impact on tumor behavior

The success of liver transplantation has led to an ever-increasing demand for liver grafts. Since the first successful living donor liver transplantation, this surgical innovation has been well established in children and has significantly relieved the crisis of donor organ shortage for children. However, the extension of living donor liver transplantation to adult recipients is limited by the graft volume. The major concern of adult-to-adult living donor liver transplantation is the adequate graft that can be harvested from a living donor. Small-for-size graft injury is frequently observed. To develop novel effective treatments attenuating small-for-size liver graft injury during living donor liver transplantation, it is important to explore the precise mechanism of acute phase small-for-size graft damage. Recently, a number of clinical studies and animal experiments have been conducted to investigate the possible key issues on acute phase small-for-size liver graft injury, such as mechanical injury from shear stress, subsequent inflammatory responses, and imbalance of vasoregulatory factors. This review focuses on the mechanism of small-for-size liver graft injury based on the number of clinical and experimental studies. The latest research findings of the significance of acute phase liver graft injury on late phase tumor recurrence and metastasis are also addressed.

Hepatic apoptosis after hemorrhagic shock in rats can be reduced through modifications of conventional Ringer's solution

BACKGROUND

Resuscitation with racemic lactated Ringer's solution induces cellular apoptosis. This study was conducted to determine if the elimination of D-lactate isomer would attenuate apoptosis in the liver, and to investigate the possible mechanisms.

STUDY DESIGN

Sprague Dawley rats (n=30, 5 per group) were subjected to modified volume-controlled hemorrhage and randomized to the following groups: no hemorrhage (sham); no resuscitation (NR); resuscitation with racemic lactated Ringer's (DL-LR); L-isomer LR (L-LR); ketone (beta-hydroxybuturate) Ringer's (KR); or pyruvate Ringer's (PR). Animals were sacrificed 2 hours later and expressions of proapoptotic proteins (BAD), antiapoptotic (bcl-2) proteins, and poly-ADP ribose polymerase (PARP) cleavage in liver were analyzed by Western blotting. Contribution of the phosphatidylinositol 3-kinase/serine/threonine kinase (PI3k/Akt) pathway was assessed by measuring total and phosphorylated PI3K, Akt, BAD, and endothelial nitric oxide synthase (eNOS) proteins. The terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay was used to detect the apoptotic cells. Liver ATP levels were measured using a luciferase reaction assay.

RESULTS

Hemorrhage significantly decreased the hepatic ATP level and resuscitation improved it, but it returned to normal only in the L-isomer lactated Ringer's and ketone Ringer's groups. Expression of proapoptotic proteins was significantly lower in the pyruvate Ringer's and ketone Ringer's groups; L-isomer lactated Ringer's and pyruvate Ringer's resuscitation significantly increased bcl-2 expression. Poly-ADP ribose polymerase fragmentation and total number of apoptotic cells were significantly increased in the racemic lactated Ringer's group. There was no significant induction of Akt activity or changes in phosphorylated BAD, Akt, or eNOS levels.

CONCLUSIONS

Resuscitation with racemic lactated Ringer's induces hepatic apoptosis, which is decreased if the D-isomer of lactate is eliminated. Apoptosis is reduced even more when lactate is substituted with beta-hydroxybutyrate or pyruvate. The beneficial effects are not through improvements in the energy status or activation of the PI3K/Akt pathway.

Isquemia e reperfusão hepática total em condições de normalidade e sob estado de choque hemorrágico controlado: efeitos no sequestro de neutrófilos no rim do rato

OBJETIVO: Avaliar os efeitos da isquemia e reperfusão hepática total em condições de normalidade e estado de choque hemorrágico controlado no acúmulo de neutrófilos no interstício do rim do rato. MÉTODOS: Foram utilizados 32 ratos adultos da raça Wistar, machos, divididos em quatro grupos: Grupo Controle (GC), condições de normalidade, submetidos às cateterizações e laparotomia, seguido de um período de 60 minutos de observação; Grupo Choque (GCh): estado de choque hemorrágico controlado (CHC) por 20 minutos (20') em pressão arterial média (PAM) de 40 mmHg, seguido de reanimação volêmica e de 60 minutos de reperfusão (RP60); Grupo Pringle (GP): Manobra de Pringle (MP) por 15 minutos (15'), seguido de RP60; Grupo Choque-Pringle (GCP): estado de CHC por 20" em PAM de 40 mmHg, seguido de laparotomia e MP por 15', seguido de RP60. Para caracterização da má perfusão tecidual foram medidos o lactato sangüíneo (LS) e a reserva de base (RB), no início do período de reperfusão (RP0), aos trinta minutos de reperfusão (RP30) e no RP60. RESULTADOS: No RP0 o valor médio do LS e RB apenas o GC apresentou níveis dentro das normalidades. Nos RP30 e RP60 o valores médios do LS e RB do GC demonstrou-se estatisticamente diferente dos demais grupos (p<0,0001). Os valores médios de neutrófilos encontrado foram: GC = 0,24 (±0,28); GCh = 1,06 (±0,61); GP = 0,18 (±0,16); GCP = 0,24(±0,19). O GC apresentou diferença estatística quando comparado aos demais, os quais não diferiam entre si. CONCLUSÃO: O presente modelo experimental demonstrou que o estado de CHC por 20' seguido de RP60 foram os principais responsáveis pelo maior seqüestro de neutrófilo no córtex renal.

Organ-specific changes in high-energy phosphates after hemorrhagic shock and resuscitation in the rat

BACKGROUND

Adenosine nucleotides provide energy for many essential cellular functions. Liver and intestinal ATP and energy charge are known to decrease during hemorrhagic shock, and the ability to regenerate high-energy phosphates may have important implications for recovery. We measured organ-specific changes in energy charge after hemorrhagic shock and after shock followed by resuscitation.

STUDY DESIGN

Anesthetized Sprague-Dawley rats were bled and maintained at a mean arterial pressure (MAP) of 40 mmHg for 1, 2, 3, or 4 hours. Some animals were resuscitated with normal saline and shed blood (1:1) to a mean arterial pressure of 80 to 90 mmHg for 1 hour. Control animals were anesthetized, but not hemorrhaged. At the conclusion, blood gases and adenine nucleotides were measured.

RESULTS

Arterial pO2 and pCO2 were normal in all groups. Unresuscitated hemorrhage caused metabolic acidosis, but bicarbonate was normal in controls and after hemorrhage followed by resuscitation. Energy charge (EC) in the gastrocnemius was unaffected by hemorrhage or resuscitation. Liver EC decreased after hemorrhage (p = 0.0001), but recovered partially after resuscitation. Kidney EC was decreased after only 3 hours of hemorrhage and 1 hour of resuscitation (p = 0.005), but not with shorter periods of hemorrhage. Lung EC decreased with shock, but was substantially worse after resuscitation (p < 0.05).

CONCLUSIONS

After hemorrhage and resuscitation, EC decreased in lung, liver, kidney, and intestine, but the time course, extent of decline, and ability to recover after resuscitation varied from organ to organ. Inability to regenerate high-energy phosphates after hemorrhagic shock may be a marker for more severe cellular damage.

Hypertonic saline dextran alleviates hepatic injury in hypovolemic rats undergoing porta hepatis occlusion

To monitor the ischemic and/or reperfusion injury after porta hepatis occlusion (Pringle maneuver) in livers subjected to hypotension, serum alanine amino transferase (ALT), liver malondialdehyde (MDA), and liver glutathione (GSH) levels were measured. MDA is a by-product of oxidant-induced lipid peroxidation, and GSH is an endogenous antioxidant. The effects of lactated Ringer's (LR) and hypertonic saline (7.5%)/Dextran (6%; HSD) resuscitation on liver injury, if any, was investigated. Rats in sham (S, n = 8) and five other groups (n = 8) underwent femoral artery and vein catheterization and laparotomy. The hemorrhage and ischemia (HI) group was bled 30% of their blood volume and had their porta hepatis occluded for 30 min. The HI, LR, and HSD groups underwent both hemorrhage and occlusion. Thirty minutes after hemorrhage, the LR and HSD groups received either LR (equivalent to three times the shed blood) or HSD (10 mL/kg) resuscitation over 30 min. Both LR and HSD resuscitation lowered the increased ALT and liver tissue MDA seen in the HI group. ALT was decreased from 348 +/- 93 IU/L in the HI group to 200 +/- 98 IU/L in the LR and 139 +/- 74 IU/L in the HSD groups. Liver tissue MDA was 353 +/- 22 nmol/g/tissue in the HI group and LR decreased it to 261 +/- 17 nmol/g/tissue, whereas HSD decreased it to 273 +/- 20 nmol/g/tissue. The decrease in ALT and the increase in liver GSH were more pronounced with HSD resuscitation (P < 0.05). HSD seems to be more effective than LR in decreasing the liver tissue damage produced by total hepatic inflow occlusion under hypovolemic conditions.

Effects of the intermittent Pringle manoeuvre on hepatic gene expression and ultrastructure in a randomized clinical study

BACKGROUND

The intermittent Pringle manoeuvre during hepatectomy results in a better clinical outcome when the accumulated ischaemia time is less than 120 min. The aim of this study was to investigate hepatic gene expression related to microcirculatory modulation and ultrastructural changes in patients having the intermittent Pringle manoeuvre.

METHODS

Forty patients who underwent hepatectomy for liver tumours were randomly assigned to liver transection with intermittent Pringle manoeuvre (Pringle group, n = 20) or without the manoeuvre (control group, n = 20). The clinical data and hepatic expression of endothelin (ET) 1 and endothelial nitric oxide synthase (eNOS) combined with liver ultrastructure were compared.

RESULTS

The Pringle manoeuvre resulted in less blood loss (8.9 versus 12.4 ml/cm(2); P = 0.034), a shorter transection time (2.7 versus 4.1 min/cm(2); P = 0.015) and a lower serum bilirubin level on postoperative day 2 (26 versus 35 microm/l; P = 0.04). The hepatic messenger RNA content of ET-1 decreased by 38 per cent of the basal level in the Pringle group, whereas it increased by 28 per cent in the control group (P = 0.026). More patients in the control group showed swelling of mitochondria in hepatocytes and disruption of sinusoidal lining cells (12 of 20 patients versus three of 20 in the Pringle group; P = 0.008).

CONCLUSION

The intermittent Pringle manoeuvre results in less disturbance of the hepatic microcirculation and better preservation of liver sinusoids after hepatectomy.

N-acetilcisteína diminui a congestão hepática na lesão de isquemia e reperfusão: estudo experimental

OBJETIVOS: A isquemia tem sido utilizada na cirurgia hepática desde o início do século. Embora possibilite a diminuição da perda sangüínea durante as ressecções e a manutenção do órgão à espera de um transplante, a ausência de perfusão traz como conseqüência um dano ao órgão, que se amplifica por ocasião da sua reoxigenação. A N-Acetilcisteína é uma droga capaz de repor os estoques celulares de glutationa, um antioxidante fundamental no controle das lesões resultantes do restabelecimento da perfusão sangüínea, esperando-se dessa forma que diminua a lesão acima descrita. Com o propósito de avaliar a capacidade da N-Acetilcisteína reduzir o dano hepático, utilizou-se um modelo murino de isquemia e reperfusão normotérmica. MÉTODO: Foram utilizados vinte ratos Wistar fêmeas, divididos em dois grupos. No grupo tratado, 400mg/kg de N-Acetilcisteína foram administrados pela via intravenosa, 15 minutos antes do clampeamento do pedículo do lobo esquerdo por 90 minutos. No grupo controle foi administrado o volume equivalente de solução fisiológica. Foi estabelecido um período de quatro horas de reperfusão, após o qual os animais foram sacrificados para a realização de análise histopatológica do lobo esquerdo com coloração de Hematoxilina-Eosina. A lesão tecidual foi quantificada quanto à presença de congestão, esteatose e necrose. RESULTADOS: O estudo evidenciou a capacidade de a N-Acetilcisteína diminuir significativamente a congestão. Não houve diferenças quanto à presença de esteatose e necrose. CONCLUSÃO: Os resultados obtidos permitem-nos concluir que o uso prévio da N-Acetilcisteína nos processos de isquemia e reperfusão, em normotermia, é capaz de diminuir a congestão hepática. A N-Acetilcisteína não diminui a presença de esteatose e necrose.

Safe upper limit of intermittent hepatic inflow occlusion for liver resection in cirrhotic rats

AIM: To evaluate the effects of varying ischemic durations on cirrhotic liver and to determine the safe upper limit of repeated intermittent hepatic inflow occlusion.

METHODS: Hepatic ischemia in cirrhotic rats was induced by clamping the common pedicle of left and median lobes after non-ischemic lobes resection. The cirrhotic rats were divided into six groups according to the duration and form of vascular clamping: sham occlusion (SO), intermittent occlusion for 10 (IO-10), 15 (IO-15), 20 (IO-20) and 30 (IO-30) minutes with 5 minutes of reflow and continuous occlusion for 60 minutes (CO-60). All animals received a total duration of 60 minutes of hepatic inflow occlusion. Liver viability was investigated in relation of hepatic adenylate energy charge (EC). Triphenyltetrazollum chloride (TTC) reduction activities were assayed to qualitatively evaluate the degree of irreversible hepatocellular injury. The biochemical and morphological changes were also assessed and a 7-day mortality was observed.

RESULTS: At 60 min after reperfusion following a total of 60 min of hepatic inflow occlusion, EC values in IO-10 (0.749 ± 0.012) and IO-15 (0.699 ± 0.002) groups were rapidly restored to that in SO group (0.748 ± 0.016), TTC reduction activities remained in high levels (0.144 ± 0.002 mg/mg protein, 0.139 ± 0.003 mg/mg protein and 0.121 ± 0.003 mg/mg protein in SO, IO-10 and IO-15 groups, respectively). But in IO-20 and IO-30 groups, EC levels were partly restored (0.457 ± 0.023 and 0.534 ± 0.027) accompanying with a significantly decreased TTC reduction activities (0.070 ± 0.005 mg/mg protein and 0.061 ± 0.003 mg/mg protein). No recovery in EC values (0.228 ± 0.004) and a progressive decrease in TTC reduction activities (0.033 ± 0.002 mg/mg protein) were shown in CO-60 group. Although not significantly different, the activities of the serum aspartate aminotransferase (AST) on the third postoperative day (POD₃) and P OD₇ and of the serum alanine aminotransferase (ALT) on POD₃ in CO-60 group remained higher than that in intermittent occlusion groups. Moreover, a 60% animal mortality rate and more severe morphological alterations were also shown in CO-60 group.

CONCLUSION: Hepatic inflow occlusion during 60 min for liver resection in cirrhotic rats resulted in less hepatocellular injury when occlusion was intermittent rather than continuous. Each period of 15 minutes was the safe upper limit of repeated intermittent vascular occlusion that the cirrhotic liver could tolerate without undergoing irreversible hepatocellular injury.

Protein kinase activation by warm and cold hypoxia- reoxygenation in primary-cultured rat hepatocytes-JNK(1)/SAPK(1) involvement in apoptosis

Ischemia-reperfusion procedures induced severe hepatic damages owing to different processes related to hypoxia and reoxygenation (H/R) phases, including the consecutive oxygen free radical (OFR) release. Stress-activated protein kinases (SAPKs) could be activated by extracellular stimuli. The aim of this study was to show whether H/R stress conditions could stimulate these kinases, and especially c-jun-N-terminal kinase (JNK(1)/SAPK(1)), to reveal a potential role of JNK(1)/SAPK(1) in the control of hepatocyte apoptosis. Primary cultured rat hepatocytes, isolated from other liver cells and blood flow, were subjected to warm and cold hypoxia-reoxygenation phases mimicking surgical and transplant conditions. The activation status of SAPKs was evaluated by immunoprecipitation or Western-blotting experiments, whereas apoptosis was assessed by measuring caspase activation and internucleosomal DNA fragmentation in vitro and by TUNEL reaction, in vivo. Hypoxia, and especially hypoxia-reoxygenation, significantly increased JNK(1)/SAPK(1) activation in cultured hepatocytes. Either in warm or cold conditions, OFR scavengers (N-Acetylcystein, Di-Phenyleneiodonium, Deferoxamine) decreased this stimulation. Warm ischemia-reperfusion also led to JNK activation. Hypoxia and especially hypoxia-reoxygenation induced programmed cell death in vivo and in vitro. This last phenomenon was inhibited when hepatocytes were treated with SB 202190, which was described as a potent inhibitor of p38 and JNK activities. Altogether, these results confirmed that JNK(1)/SAPK(1) was activated during the hypoxia-reoxygenation process, and that this activity participated in the onset of the apoptosis program.

Glutathione and ultrastructural changes in inflow occlusion of rat liver

BACKGROUND

Liver ischemia/reperfusion is frequently associated with organ injury to which reactive oxygen species contribute. The aim of our study was to evaluate cytosolic and mitochondrial glutathione levels and morphological changes in hepatocytes of rat liver in an experimental model of ischemia/reperfusion.

MATERIALS AND METHODS

The experimental procedure consisted of temporary interruption of blood flow to the left lateral and medial hepatic lobes for different lengths of time and, in some cases, subsequent reperfusion. Cytosolic and mitochondrial glutathione levels were evaluated and ultrastructural analysis was carried out for all samples.

RESULTS

Ischemic lobes showed ultrastructural changes in relationship with the increase in ischemia time. Total glutathione levels did not show variations in ischemic lobes and sham lobes with respect to control rats during ischemia only. Instead, during reperfusion, significant ultrastructural alterations of the hepatocytes and a significant depletion of glutatione in cytosolic and mitochondrial compartments were evident. The sham lobes also showed a significant glutathione decrement. Increased oxidized glutathione (GSSG) levels were found during ischemia both in ischemic lobes and in sham lobes. During reperfusion GSSG was found to a minor extent, in the cytosolic compartment. In mitochondria GSSG levels were also high during reperfusion.

CONCLUSIONS

We conclude that depletion of glutathione contributes to impaired liver after reperfusion following ischemia but depletion of glutathione alone does not induce changes in the morphology of the hepatocytes. Glutathione depletion and a greater quantity of GSSG, even in sham lobes, may indicate a metabolic alteration which spreads to compartments that are not involved in ischemia/reperfusion.

Selective type III phosphodiesterase inhibition prevents elevated compartment pressure after ischemia/reperfusion injury

BACKGROUND

A new synthetic cyclic adenosine monophosphate phosphodiesterase inhibitor, cilostazol, has been shown to inhibit platelet aggregation and act synergistically with endogenous prostaglandin I2 to enhance smooth-muscle cell vasodilitation. The effect of cilostazol in ischemia/reperfusion injury-induced compartment syndrome was investigated.

METHODS

Sixteen rabbits underwent femoral artery occlusion after ligation of branches from the terminal aorta to the femoral artery. After 7 hours of ischemia, reperfusion was established with heparinized polyethylene shunts. Experimental animals (n = 8) received cilostazol (3.0 mg/kg) and control animals (n = 8) received normal saline as an intravenous infusion 10 minutes before shunt placement. During reperfusion, anterior compartment pressure was continuously monitored in the left lower extremity, and femoral artery blood flow was measured by laser Doppler fluorometry. To quantitate skeletal muscle oxidative metabolism and viability, triphenyltetrazolium chloride (TTC) reduction (micrograms of TTC per milligram of protein) of tibialis anterior muscle from the right lower extremity was measured at femoral artery occlusion, 7 hours of ischemia, and 2 hours of reperfusion. To assess tissue edema, dry/wet weight ratios were also determined at these intervals. Data were expressed as means +/- SE. Comparisons within groups were performed by analysis of variance, and comparisons between groups with two-tailed unpaired t tests.

RESULTS

At 2 hours of reperfusion, the difference between controls and cilostazol-treated animals was extremely significant (p = 0.0008). Preischemia and 2-hour reperfusion TTC and dry/wet weight ratios were not significantly different within or between experimental groups, nor was femoral artery blood flow during reperfusion.

CONCLUSION

Cilostazol inhibits the increase in compartment pressure central to the development of the compartment syndrome. The mechanism appears to be independent of altered tissue permeability or oxidative metabolism.

Evaluation of serum uric acid changes in different forms of hepatic vascular inflow occlusion in human liver surgeries

Uric acid values in serum have been analyzed as one of the markers to predict cellular damage due to ischemia reperfusion injury in the field of organ transplantation. The present study was conducted to confirm that uric acid values in serum could be an efficient marker of ischemic injury of liver parenchyma following hepatic vascular occlusion in human liver surgery. The changes in serum uric acid values were analyzed at fixed intervals during different liver surgeries. Significant increases in serum uric acid values were observed in patients who received the Pringle's maneuver in which hepatic vascular inflow was manipulated with a repetition of 15 min occlusion and 5 min perfusion, whereas almost no changes in uric acid values were found in both groups of patients who received the hemilobal occlusion of the Glisson's triad in which the right or left vessels were manipulated with a repetition of 30 min occlusion and 5 min perfusion and the "control method" in which the hepatic vessels of the lesion side were previously cut before liver resection. Uric acid values in serum increased in patients of Pringle's maneuver compared to those of the hemilobal occlusion of the Glisson's triad and the control method though these procedures were used in larger hepatectomies rather than Pringle's maneuver. The results indicated that serum uric acid values do not always reflect the severity of ischemia of the liver parenchyma but reflect intestinal congestion because marked intestinal congestion was observed in patients of Pringle's maneuver but not in patients of the hemilobal occlusion of the Glisson's triad and the control method. The evaluation of the severity of the ischemic injury of the liver should be done with caution when uric acid is used as a marker in human liver surgery.

Uric acid changes in serum during different forms of hepatic vascular inflow occlusion

The present study was conducted to develop an efficient marker which can evaluate the influence of the occlusion of hepatic vascular inflow, which technique is commonly used in major liver surgery or in liver transplantation. Serum samples from the rats induced by hepatic vascular inflow occlusion were analyzed with high performance liquid chromatography with the electrochemical detection, and a substance which changed in accordance with the duration of the occlusion was obtained. Both the retention time and the ultraviolet absorption spectra of the substance completely agreed with those of an authentic uric acid and the substance was ultimately determined to be uric acid. To evaluate the changes in serum uric acid during different forms of hepatic vascular inflow occlusion we devised the four types of experimental model, viz. the occlusion of hepatic artery, portal vein, both hepatic artery and portal vein and both hepatic artery and portal vein of left hepatic lobes. From the device of experiments our results indicated that in the early stage of hepatic vascular inflow occlusion the high values of serum uric acid did not reflect the damage of hepatic circulation but rather responded to the intestinal congestion. Our results also indicated that even after the declamping of hepatic vascular inflow if high values of serum uric acid are prolonged it means the deterioration of the portocaval circulation including both intestinal and hepatic circulation. So that the evaluation of the severity of injured liver due to hepatic vascular inflow occlusion should be done with the caution especially in vivo study when uric acid values are used as a marker.

Mortality, endotoxaemia and cytokine expression after intermittent and continuous hepatic ischaemia

This study compared mortality rates, endotoxaemia, systemic tumour necrosis factor (TNF) and interleukin (IL)-6 concentrations after continuous and intermittent hepatic ischaemia. Two groups of rats were subjected to continuous or intermittent left hepatic inflow occlusion for a total period of 120 min in each group. Intermittent ischaemia was associated with significantly lower mortality rates than continuous ischaemia (four of 20 versus 15 of 20; P = 0.0015). In a separate study, again following 120 min continuous or intermittent ischaemia, systemic blood was sampled at 0 min, 1 h, 3 h and 5 h after final clamp release for measurement of endotoxin, TNF and IL-6 concentrations. Endotoxin concentrations were significantly lower at 1 h, as were TNF and IL-6 concentrations at 3 and 5 h, after final clamp release in the group having intermittent ischaemia (P < 0.05). Intermittent ischaemia is associated therefore with significantly reduced mortality rates and lower systemic endotoxin, TNF and IL-6 concentrations when compared with continuous ischaemia.

Venous air embolism, preservation/reperfusion injury, and the presence of intravascular air collection in human donor livers: a retrospective clinical study

In human liver transplantation, air embolism is seldom encountered after graft reperfusion. Nevertheless, despite adequate flushing and clamping routines, air emboli have been reported in transesophageal echocardiography (TEE) studies performed during the reperfusion phase. We retrospectively investigated whether air in the donor liver -- as observed with pretransplant magnetic resonance imaging (MRI) -- resulted in clinical air embolism or contributed to preservation/reperfusion injury. Clinical air embolism was assessed by intraoperative hemodynamics and end-tidal CO2 monitoring. Preservation/reperfusion injury was assessed in postoperative biochemical measurements. The outcomes were compared between patients receiving livers containing significant intrahepatic air and patients receiving livers without intrahepatic air. Forty-three livers were studied, seven which had major intrahepatic air and ten of which had no evidence of air collections. Twenty-six livers showed minor amounts of air and were excluded from further study. One patient who received a liver that did not contain intrahepatic air had clinical evidence of air embolism. Clinical air embolism did not appear to be associated with the presence of significant intrahepatic air based upon pretransplant MRI. Intrahepatic air did not seem to affect the amount of preservation/reperfusion injury. Our data indicate that air bubbles in the portal and arterial branches are absorbed during reperfusion and that the majority of intrahepatic air is effectively removed by the specific flushing routines.

"Varicoid change" of bile canaliculi in rat liver at an early phase of ischaemia-reperfusion injury

To elucidate early changes and the mechanism of ischaemia-reperfusion liver injury, we investigated three-dimensional microstructural changes of cellular actin filaments in rat livers using confocal laser scanning microscopy. The liver tissues of a reperfusion group were examined 12 h after removal of a vascular clamp. Fixed tissues were stained with fluorescein-labelled phalloidin to obtain stereoscopic images of the actin filaments and these were compared with histological findings. The images of bile canaliculi showed that multiple abnormal minute diverticula arose from the canalicular membranes and fused with one another, resulting in irregular dilation of the bile canaliculi. These changes were observed after 15 min of ischaemia and reperfusion in which no significant necrosis was seen. The frequency and degree of these changes were strictly dependent on the periods of ischaemia (15-60 min). We called these bile canacilular lesions "varicoid changes". The liver of an ischaemia group taken after persistent clamping without reperfusion did not show these changes. Our findings suggest that the varicoid change in the bile canaliculi is probably due to alterations in the actin polymerization-depolymerization cycle and is a pathognomonic change of ischaemia-reperfusion liver injury.

Hypoxic hepatitis in patients with cardiac failure: incidence in a coronary care unit and measurement of hepatic blood flow

The incidence of hypoxic hepatitis was prospectively studied for 1 year in a group of high-risk patients suffering from low cardiac output in a coronary care unit. Hypoxic hepatitis, defined as an increase in serum aminotransferase activity of at least 20 times the upper limit of normal without any other cause for hepatic necrosis, was observed in 20 patients. This represents 2.6% of the 766 patients admitted to the unit during this period and 21.9% of the 91 patients suffering from low cardiac output. Clinical, biological and hemodynamic data were compared between 20 patients with low cardiac output and hypoxic hepatitis, and 48 patients with low cardiac output but without hypoxic hepatitis who survived more than 24 h. In these two groups of patients, hepatic blood flow was measured by galactose clearance at low concentration. Patients with hypoxic hepatitis exhibited a higher central venous pressure (90% versus 38%-p < 0.001) as well as a lower hepatic blood flow (867 +/- 377 ml/min versus 1429 +/- 644 ml/min-p = 0.001). In conclusion, although it is considered a rare hepatic disorder, hypoxic hepatitis is frequent in patients with low cardiac output admitted to the coronary care unit, and is associated with a decrease in hepatic blood flow and passive hepatic venous congestion.