Analysis of factors affecting the graft oxygenation state in living related liver transplantation.

BACKGROUND/AIMS: In liver transplantation, graft dysoxia after reperfusion may lead to graft failure. The aim of this study is to investigate the relationship between the factors, which were supposed to affect the oxygen supply to the graft, and the oxygenation state of the graft in order to determine which factor is important to prevent the graft from dysoxia. MATERIALS AND METHODS: The relationship between oxygen supply and oxygenation state of the graft was investigated in 56 successful cases of living related liver transplantation. Factors affecting the oxygen supply to the graft were considered as follows; portal venous flow (PVF), mean velocity of the hepatic artery (HA-Vm), hemoglobin concentration in the peripheral blood (Hb), size of the graft liver relative to the recipient body weight (G/R ratio), partial oxygen pressure in the arterial blood (PaO2), and rate-pressure product (BP*PR). Oxygenation state of the graft was estimated by oxygen saturation of hemoglobin in the graft tissue (graft SO2) as measured by tissue near infrared spectroscopy. RESULTS: 1) Graft SO2 was rather independent of PVF and HA-Vm probably due to compensatory interrelation between the portal venous flow and hepatic arterial flow. 2) Significant correlation between G/R ratio and graft SO2 was observed after portal reflow (p < 0.01), but the correlation diminished after hepatic arterial reflow. Positive correlation between G/R ratio and AKBR after portal reflow suggested that the graft with large G/R ratio is likely to suffer dysoxia early after reperfusion. 3) Graft SO2 was positively correlated with Hb (p < 0.05), while there was no significant correlation between graft SO2 and PaO2 or BP*PR. CONCLUSION: This study clarified the contribution of the factors which were supposed to affect the oxygen supply to the graft and the oxygenation state of the graft, and which factor is important to prevent the graft from dysoxia.

Direct measurement of hepatic indocyanine green clearance with near-infrared spectroscopy: separate evaluation of uptake and removal.

We continuously measured hepatic absorbance of indocyanine green (ICG) using near-infrared (NIR) spectroscopy after intravenous bolus injection in rabbits. Hepatic ICG concentration was obtained by subtracting out the absorbance of hemoglobin and other pigments within the liver. Two exponential rate constants, the first reflecting the dye uptake from plasma to the hepatocytes, and the second representing the dye removal from the liver by cytoplasmic transport and biliary excretion, were determined by fitting the time-course curve of hepatic ICG concentration to a two-compartment model with irreversible transfer between the two compartments, as defined by the double-exponential equation: [ICG]liver(t) = -A exp(-alpha t) + B exp(-beta t). The results showed that treatment with bilirubin, a competitive inhibitor of ICG uptake, caused a decrease in alpha. Treatment with either colchicine, which is toxic to microtubules, or with ouabain, an inhibitor of Na+,K(+)-ATPase, caused a decrease in beta. These results were compatible with the kinetic model. This new method was then used in liver-injured rabbits inflicted with hemorrhagic shock and ischemia-reperfusion, to show that the first rate constant is primarily affected by hepatic microcirculatory condition, and the second refers closely to parenchymal liver damage. In another series of partial liver ischemia-reperfusions, it was possible to simultaneously and separately monitor the ICG profiles of post-ischemic and nonischemic areas. Thus, the kinetic analysis of hepatic ICG concentration curves, as directly measured by NIR spectroscopy, led to the separate evaluation of different clearance process of ICG in the liver, suggesting the advanced utility as a comprehensive liver function test.

Quantitative analysis of redox gradient within the rat liver acini by fluorescence images: effects of glucagon perfusion.

The redox gradient along the sinusoid in the rat liver was studied using a redox scanner, a device based on tissue fluorescence scanning spectroscopy measuring the fluorescence signals of oxidized flavoprotein (FP) and reduced pyridine nucleotide (PN). The FP/(FP+PN) ratio reflects the mitochondrial redox state in the liver tissue. The distribution of mitochondrial redox state on the scanned area is expressed as two-dimensional gray-scale images with a 20 micron resolution. Using this instrument, we have scanned a 2.5 x 2.5 mm area of the frozen rat liver sample to investigate the redox gradient within acini and the effects of glucagon on the changes in the redox distribution. The redox images obtained in the perfused livers showed mosaic patterns implicating a regular heterogeneity of redox state in an acinus. The analysis of gradient curve, furthermore, clarified that the redox level in an acinus decreased sigmoidally from the periportal to the pericentral region. Glucagon, which has been reported to reduce the intracellular redox state, decreased the redox potential in whole acini, especially, in the periportal region, when compared with the perfusion without glucagon. These results strongly indicate an intraacinus heterogeneity of glucagon function, with glucagon selectively operating in the upstream of the sinusoid.

Primary and reversible injury of H(+)-ATPase in warm ischemia and reperfusion of rat liver in relation to intramitochondrial adenine nucleotide.

The injury and recovery processes of complex reactions of liver mitochondrial ATP synthesis during warm ischemia and after reflow were studied separately in terms of the changes in oxidation (electron transfer system) and phosphorylation (H(+)-ATPase). Oxidative activity decreased significantly from the control value of 40 +/- 0.9 (mean +/- SEM, n = 5) to 31.5 +/- 1.13 (nanoatoms oxygen consumed/min/mg protein) after 40 min of warm ischemia, while phosphorylative activity decreased significantly from the control value of 1.06 +/- 0.12 to 0.42 +/- 0.03 (mumole ATP hydrolyzed/min/mg protein) after 20 min of warm ischemia. During 120 min of reflow after 20 min of warm ischemia, the decreased phosphorylation activity recovered to 0.52 +/- 0.01 concomitant with a recovery of intramitochondrial total adenine nucleotide and an increase in the ATP/ADP ratio, while oxidative activity decreased further to 23.9 +/- 0.81. These results indicate that H(+)-ATPase is more vulnerable to warm ischemia than the electron transfer system, but that it is restored concomitant with the recovery of intramitochondrial adenine nucleotide content.

Evaluation of water molecules in the cold-preserved rat liver by proton magnetic resonance imaging.

Hypothermically preserved rat livers were studied with proton magnetic resonance imaging (1H-MRI) under proton density-, spin-lattice relaxation time-, spin-spin relaxation time- and diffusion-weighted (P-W, T1-W, T2-W and D-W) conditions. Relative signal intensities (RSI) of the liver to distilled water in terms of P-W, T1-W, T2-W and D-W increased time-dependently during 12 h hypothermic (4 degrees C) preservation with saline, while these parameters did not increase during preservation with University of Wisconsin (UW) solution. One-hour Wiggers' hypotensive treatment before the harvesting increased the RSIs of P-W, T2-W and D-W, and the subsequent 12-hour preservation with UW solution did not improve the increased RSIs. These results suggest that 1H-MRI has potential application in evaluating the biophysical changes of water molecules in the liver graft, which were measured by placing the harvested liver in a plastic bag under a magnetic field at a low temperature.

Intraoperative measurement of the graft oxygenation state in living related liver transplantation by near infrared spectroscopy.

Graft oxygenation plays an important role in successful liver transplantation. Intraoperative changes in the oxygenation state of the liver graft were measured by near infrared spectroscopy in 28 cases of living related liver transplantation. Oxygen saturation of hemoglobin in the liver (hepatic SO2) changed from 81.2% +/- 1.5% (mean +/- SEM) before donation (in the donor) to 49.7% +/- 4.2% after portal reflow, to 58.4% +/- 5.0% after arterial reflow, and then to 71.4% +/- 3.9% before closure. Mean hepatic SO2 was positively correlated with portal flow rate as measured by duplex Doppler sonography. Cases with low portal flow rate showed a high coefficient of variation (SD/mean) of hepatic SO2, indicating heterogeneous tissue oxygenation. Though graft size was expected to affect the graft oxygenation state, hepatic SO2 was fairly independent of the graft-to-recipient weight ratio. In two cases with markedly low hepatic SO2, postoperative graft dysfunction occurred. This study suggest that the method of near infrared spectroscopy is reliable and useful for assessing the graft oxygenation state in liver transplantation.

Cold preservation-induced changes in oxygen radical generation between parenchymal and nonparenchymal cells in rat liver.

Many of the reports implicating the contribution of oxygen radicals to preservation-reperfusion injury have been based largely on indirect experiments demonstrating the effects or the consumption of various antioxidants. Investigations based on the direct measurement of the amounts of oxygen radicals that are actually formed during reoxygenation after preservation have not given satisfactory results. In this study, we attempted direct measurement of H2O2 from hepatocellular mitochondria and superoxide (O2-) from Kupffer cells, using the HRP method and cytochrome c perfusion method, respectively, for quantitative comparison of the cold preservation-induced changes in radical generation activity between these sources. H2O2 generation in mitochondria isolated after 24 h cold preservation decreased to 8% of non-preserved liver, but in the mitochondria isolated from the livers that were reperfused for 30 min after 24 h preservation H2O2 generation recovered to 60%. The respiratory control ratio also decreased significantly after 24 h preservation, and similarly recovered after an additional 30 min reperfusion. By contrast, O2- from Kupffer cells increased in time-dependent fashion until 12 h preservation and decreased after 24 h preservation. Although 12 h preservation did not cause an increase in LDH release, the lipid peroxide in the perfusate significantly increased after 12 h preservation, which indicated the occurrence of lipid peroxidation in the sinusoidal area. These results suggested that mitochondrial H2O2 was dependent upon the activity of respiratory function and so did not cause hepatocellular injury and that O2- from Kupffer cells contributed to oxidative injury to the sinusoidal lining cells. Our data support reports demonstrating the vulnerability of nonparenchymal cells.

Changes in the distribution of the control of the mitochondrial oxidative phosphorylation in regenerating rabbit liver.

Applying the metabolic control theory, inhibitor titration studies were carried out on Complex I, III, IV, ATP synthase, ATP/ADP carrier and P(i) carrier of mitochondrial oxidative phosphorylation in normal and regenerating rabbit liver in order to examine the acceleration mechanism of mitochondrial oxidative phosphorylation. In regenerating rabbit liver the rate of state 3 respiration, respiratory control ratio and phosphorylation rate in the presence of mM glutamate, 250 microM ADP and 3 mM inorganic phosphate increased significantly as compared with the control by 73%, 48% and 76%, respectively. The control of the rate of state 3 respiration in normal liver was exerted by Complexes I, IV and steps other than the aforementioned six steps, whose flux control coefficients were 0.317, 0.214 and 0.469, respectively. By contrast, in regenerating liver, the control was more evenly distributed among these steps in oxidative phosphorylation and the possibility is suggested that Complexes I, IV and steps other than the six steps are activated during regeneration. The activation of Complexes I and IV was attributed to their increased activity, since it was not accompanied by an increase in the amount of the enzymes.

Living related liver transplantation across ABO blood groups.

We performed 13 pediatric liver transplants from ABO-incompatible living related maternal or paternal donors using a combination of preoperative removal of isohemagglutinin and postoperative immunosuppressive therapy with FK506 and prophylactic OKT3. Tissue near-infrared spectroscopy was applied to evaluate hemodynamics using the hemoglobin of red cells in the sinusoids as an index. The data obtained indicated that the preoperative removal of isohemagglutinin prevented hyperacute humoral rejection with hemorrhagic infiltration in the sinusoids in 10 successful cases. The incidence of acute rejection was not significantly different among ABO-identical, -compatible, and -incompatible groups. The estimated 1-year survival rate of the ABO-incompatible group was 77%.

Interrelationship of oxygen supply by hepatic artery and portal vein: rapid analysis of ischemia-reflow-induced changes in hepatic oxygenation in experimental and clinical subjects by tissue near-infrared spectroscopy.

The rapid changes in extracellular oxygenation and intracellular oxidation during ischemia and reflow were measured in deep liver tissue by a novel method combining tissue near-infrared spectroscopy with multicomponent curve-fitting analysis. This method enabled us to make real-time measurements of oxygen saturation (SO2) and amount (THB) of hemoglobin in the liver sinusoid as parameters of extracellular oxygenation state and of redox transition of cytochrome aa3 as intracellular oxidation state. Clamping of the hepatic artery in rabbit decreased the THB with a transient fall of SO2. Clamping of the portal vein decreased both SO2 and THB. The decreases of SO2 and THB caused by Pringle's maneuver were larger than the sum of decreases by hepatic artery and portal vein. These changes in SO2 were correlated with intramitochondrial oxidation state as measured by cytochrome aa3. These results indicate the presence of an interrelationship of oxygen supply by hepatic artery and portal vein. This method was clinically applied during and after clamping of hepatic artery and portal vein in 19 cases of hepatic resection with or without chronic hepatic diseases. The decrease in SO2 values before and after clamping (SO2D) and the slope of SO2 recovery (SO2R) after release were calculated. SO2D and SO2R values of the portal vein in cirrhotics were significantly higher and lower, respectively, than those in the normal liver. These data indicate that the present method provides a rapid and reliable method of quantifying hepatic oxygenation during liver surgery and its perioperative management.

Delayed oxidation of intramitochondrial pyridine nucleotide oxidoreduction state as compared with tissue oxygenation in human liver transplantation.

Intra- and post-operative oxygenation of graft liver and subsequent oxidation of the intramitochondrial oxido-reduction state of pyridine nucleotide were studied in partial liver transplantation from living related donors with the ratio of acetoacetate to beta-hydroxybutyrate in arterial blood (AKBR), the ratio of oxidized flavoprotein to reduced pyridine nucleotide (FP/PN ratio) and oxygen saturation of hemoglobin in liver tissue (hepatic SO2). Decreased hepatic SO2 and its heterogenous distribution after reflow of portal vein and hepatic artery were normalized by the end of operation, while the intramitochondrial oxido-reduction state was still reduced at the end of operation and was normalized only at 24 h after the operation. The observed delay in oxidation of the intramitochondrial oxido-reduction state as compared with tissue oxygenation indicates the transition of the intramitochondrial oxido-reduction state associated with the initiation of metabolic activity from the cold preserved state, and suggests an important role for microcirculation in the normalization of the oxido-reduction state.

[A case of mesothelioma of the pleura with pneumothorax].

A 49-year old man underwent an operation for pneumothorax, during which a tiny tumor on internal surface of the thoracic wall was extirpated. As the tumor proved to be malignant mesothelioma postoperatively, it was planned to be followed up strictly after discharge, but the patient did not visit for 6 months after discharge. When he was admitted again because of cough and fever, the mesothelioma had already disseminated diffusely in the whole thoracic cavity. So he underwent total pleuropneumonectomy, but died 49 days after operation.