Toshiyuki Kitai

Linear correlation between acetoacetate / β-hydroxybutyrate in arterial bllod and oxidized flavoprotein / reduced pyridine nucleotide in freeze-trapped human liver tissue

A comparison of two methods of measuring liver mitochondrial redox state demonstrated that a linear correlation exists between acetoacetate/beta-hydroxybutyrate ratio in arterial blood (arterial ketone body ratio; AKBR) and oxidized flavoprotein/reduced pyridine nucleotide in human liver tissue (FP/PN) as measured by tissue fluorescence spectroscopy, such that [FP/PN] = 0.64 + 0.49 x [AKBR] (r = 0.84, P less than 0.001). This result supports the validity of AKBR as a method of measuring the hepatic mitochondrial redox state of pyridine nucleotide using arterial blood.

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%.

Graft size‐matching in living related partial liver transplantation in relation to tissue oxygenation and metabolic capacity

The influence of graft size-matching on tissue oxygenation and metabolic capability was studied in living related partial liver transplantations for 47 pediatric patients. Their age ranged from 4 months to 17 years 3 months, their body weight from 4.0 to 58.0 kg, graft weight from 191 to 440 g, and graft weight/recipient body weight ratio from 0.61% to 6.0%. Tissue oxygenation and its heterogeneity were investigated by measuring oxygen saturation of hemoglobin in the liver sinusoid (SO2), coefficient of variation of SO2, and arterial ketone body ratio. The metabolic capacity of the graft was investigated by measuring bilirubin clearance, recovery of cholesterol esterification, and ketone body production. In infants with a relatively large liver graft, both intra- and extracellular oxygenation remained low soon after reperfusion but recovered to the control value by the end of the operation. In adolescent recipients of a relatively small graft, by contrast, synthetic and detoxification capacities were relatively deficient; however, these improved with time. These results indicate that sufficient tissue oxygenation and liver regeneration are essential for successful liver transplantation with relatively large and small grafts, respectively.

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.

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

Abstract 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.

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.

Pneumoperitoneum following the spontaneous rupture of a gas-containing pyogenic liver abscess: report of a case.

Abstract We report herein the case of a ruptured liver abscess that resulted in pneumoperitoneum. A patient with diabetes mellitus presented with symptoms of acute abdomen. The plain abdominal radiograph and computed tomography findings revealed abdominal free air and a gas-containing liver abscess, whereby a diagnosis of a ruptured liver abscess was made. An emergency operation was performed, and the abscess was drained followed by peritoneal lavage and the administration of appropriate antibiotics. To the best of our knowledge, very few cases of spontaneous pneumoperitoneum occurring secondary to the rupture of a gas-containing liver abscess have been encountered in Japan.

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.

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 Pringles 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.

Clinical Report on the First Prototype of a Photoacoustic Tomography System with Dual Illumination for Breast Cancer Imaging.

Photoacoustic tomography is a recently developed imaging modality that can provide high spatial-resolution images of hemoglobin distribution in tissues such as the breast. Because breast cancer is an angiogenesis-dependent type of malignancy, we evaluated the clinical acceptability of breast tissue images produced using our first prototype photoacoustic mammography (PAM) system in patients with known cancer. Post-excisionally, histological sections of the tumors were stained immunohistochemically (IHC) for CD31 (an endothelial marker) and carbonic anhydrase IX (CAIX) (a marker of hypoxia). Whole-slide scanning and image analyses were used to evaluate the tumor microvessel distribution pattern and to calculate the total vascular perimeter (TVP)/area for each lesion. In this clinical study, 42 lesions were primarily scanned using PAM preoperatively, three of which were reported to be benign and were excluded from statistical analysis. Images were produced for 29 out of 39 cancers (visibility rate = 74.4%) at the median depth of 26.5 (3.25–51.2) mm. Age, menopausal status, body mass index, history of neoadjuvant treatment, clinical stage and histological tumor angiogenesis markers did not seem to affect the visibility. The oxygen saturation level in all of the measured lesions was lower than in the subcutaneous counterpart vessels (Wilcoxon test, p value<0.001), as well as in the counterpart contralateral normal breast region of interest (ROI) (Wilcoxon test, p value = 0.001). Although the oxygen saturation level was not statistically significant between CAIX-positive vs. -negative cases, lesional TVP/area showed a positive correlation with the oxygen saturation level only in the group that had received therapy before PAM. In conclusion, the vascular and oxygenation data obtained by PAM have great potential for identifying functional features of breast tumors.