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Biomedical subjects

I Hamamoto

Publications and source records attributed to I Hamamoto.

At least 55 records · Page 3Linked to original sources
PubMed1993

Evaluation of oxygen necessity during hypothermic liver perfusion.

Need of oxygen by the liver during hypothermic perfusion was evaluated using isolated perfusion model. Livers were perfused by a continuous perfusion system with oxygen saturated perfusate or nitrogen saturated perfusate, or simply stored for 12 hours at 5 degrees C. Quality of individual liver was assessed at one hour after normothermic reperfusion. Tissue edema was significant in all experimental groups, but the extent of which was much higher in nitrogen and simple cold storage groups. AST, ALT, LDH and PNP in the perfusate at the end of normothermic reperfusion were significantly higher in nitrogen and simple storage groups and those of oxygen group were similar to the control. Tissue adenine nucleotide and purine catabolite concentration in oxygen group was almost identical to the control at the end of hypothermic preservation, while ATP and energy charge in nitrogen and simple cold storage groups were significantly low. Conjugated dienes before and after reperfusion showed no difference in any groups, indicating no involvement of free radical injury on reperfusion in this asanguineous perfusion model. These results suggest that continuous supply of oxygen is necessary for liver preservation even though the temperature is lowered to inhibit cellular metabolism.

Animals↗
PubMed1993

Isolated perfusion of rat livers: effect of temperature on O2 consumption, enzyme release, energy store, and morphology.

The effect of temperature on isolated rat liver perfusion was studied. Livers were perfused for 12 hours with oxygenated Krebs-Henseleit solution at 5, 10, 15, 20, 25 and 30 degrees C, followed by one hour normothermic reperfusion. After each perfusion, oxygen consumption, liver enzyme release, tissue swelling, energy metabolism and histopathological abnormalities were determined. Compared to the oxygen consumption at 37 degrees C, that of 25, 10 and 5 degrees C was 47%, 16% and 12%, respectively. When the liver was perfused at 30 degrees C, higher enzyme release and lower energy status was observed. Tissue swelling was significant only with livers perfused at 5, 10 and 30 degrees C. After normothermic reperfusion, liver injury indicated by enzyme release and bile production was remarkable with 30 degrees C liver, and that of the other groups was essentially the same as the control. ATP of 5, 25 and 30 degrees C liver was significantly lower than the control. Histopathological examination demonstrated abnormalities of sinusoidal cells and hepatocytes in livers perfused at 25 degrees C and 30 degrees C Thus higher temperature (25 degrees C to 30 degrees C) during continuous perfusion were found to induce liver damage. Moderate hypothermia between 10 degrees C and 20 degrees C maintained structure and function of rat livers rather well. These results suggest that, when a machine perfusion of the liver is attempted, a wider temperature range, higher than the conventional, needs to be taken into consideration.

Alanine Transaminase↗
PubMed1993

Rat liver lipids during ex vivo warm and cold ischemia and reperfusion.

Rat livers were flushed and stored ex vivo in Krebs-Henseleit buffer at 37 degrees C for 3 hr or in University of Wisconsin solution at 2 degrees C for 48 hr. After this they were perfused with recirculated Krebs-Henseleit solution at 37 degrees C for 1 hr. Levels of phospholipids (PL), free fatty acids (FFA), and conjugated dienes were determined at various times during ischemia and after 1 hr of reperfusion. After 3 hr warm ischemia, total PL content decreased by about 30% primarily because of decreases in phosphatidylcholine and phosphatidylethanolamine. One hour of reperfusion normalized PL levels. Total PL content was unchanged up to 48 hr of cold ischemia because of offsetting alterations in levels of PL classes. FFA accumulation during warm ischemia was about half that during cold ischemia. Conjugated diene concentration increased fivefold during warm ischemia but was unchanged during cold ischemia. Low PL levels and FFA accumulation along with production of conjugated dienes suggest that lipid oxidation is a major mechanism of PL degradation during warm, but not cold, ischemia of the liver.

Animals↗
PubMed1993

Effects of ionic strength and pH on the dissociation constant between NADPH-adrenoferredoxin reductase and adrenoferredoxin.

The dissociation constant between NADPH-adrenoferredoxin reductase and adrenoferredoxin was measured at various ionic strengths (0.05-0.25) and pHs (6.6-8.2) by means of a kinetic method involving pyridoxal 5'-phosphate. For each ionic strength, the maximum dissociation constant was obtained at pH 7.4. It ranged from 8.34 (ionic strength = 0.05) to 169 nM (ionic strength = 0.25) at pH = 7.4. At each pH, the dissociation constant increased along with the increase in ionic strength.

Adrenodoxin↗
PubMed1993

Sodium lactobionate sucrose solution for canine liver and kidney preservation.

With 24-hour preservation of canine liver, SLS solution showed inferior animal survival to UW solution. The lactobionate, raffinose, glutathione, and hydroxyethyl starch in UW solution have been shown to be important for liver preservation. However, our results suggest that sucrose should not be substituted for raffinose for the preservation of livers. In contrast to the liver, SLS solution performed the same or even better than UW solution for kidney preservation. The substitution of sucrose for raffinose, along with the addition of CPZ has either no effect or a slightly positive effect on kidney preservation. In conclusion, SLS solution may be a suitable solution for preserving canine kidneys, but is not suitable for liver preservation. These findings suggest that future development of preservation solutions should be focused on the needs of specific organs and not toward a generic, all encompassing preservation solution.

Animals↗
PubMed1992

University of Wisconsin solution for pulmonary preservation in a rat transplant model.

University of Wisconsin and modified Euro-Collins solutions for pulmonary preservation were compared in a rat orthotopic left lung isotransplant model. Heart-lung blocks of donor rats were flushed with and preserved in one of the preservation solutions at 0 degrees C. After 6 or 12 hours of cold ischemia, the left lungs were transplanted into recipient rats and reperfused for 1 hour. Pulmonary function was assessed by measuring oxygen and carbon dioxide tensions in arterial blood after removal of the right lung. Lipid peroxide concentrations were measured as thiobarbiturate acid-reactive substances. The ratios of wet to dry weight of grafts after ischemia and after reperfusion were calculated. Histologic changes of ischemia-reperfusion injury of the lung tissue were evaluated using a graded scale. Oxygen tension after 6 hours of preservation followed by reperfusion was significantly higher with University of Wisconsin solution (308.8 +/- 81.1 mm Hg) than with Euro-Collins solution (50.8 +/- 17.8 mm Hg; p less than 0.001). Carbon dioxide tension in the University of Wisconsin solution group was also significantly lower than in the Euro-Collins solution group (28.2 +/- 2.3 versus 46.0 +/- 4.5 mm Hg; p less than 0.05). Lipid peroxide concentration after 6 hours' preservation in University of Wisconsin solution was significantly lower (0.88 +/- 0.07 mumol/g) than that in Euro-Collins solution (1.26 +/- 0.12 mumol/g; p less than 0.05). After 12 hours of preservation only lipid peroxide concentration with University of Wisconsin solution was significantly lower (1.30 +/- 0.09 mumol/g) than with Euro-Collins solution (1.71 +/- 0.15 mumol/g; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1992

Lazaroid U74500A as an additive to University of Wisconsin solution for pulmonary grafts in the rat transplant model.

Lazaroids are a class of novel 21 aminosteroids. They have been reported to be potent inhibitors of lipid peroxidation, which is a major contributing factor to ischemia-reperfusion injury in the lung. A Lewis rat orthotopic left lung isotransplant model was used to investigate the effects of the lazaroid U74500A on pulmonary preservation. The heart-lung blocks of donor rats were flushed with and then stored in either standard University of Wisconsin solution or University of Wisconsin solution with 30 mumol/L of U74500A substituted for the dexamethasone. After 6 or 12 hours of cold storage at 0 degrees C, the left lungs were transplanted into recipient rats and reperfused for 1 hour. Pulmonary function was assessed by measuring oxygen and carbon dioxide tensions in arterial blood after removal of the right lung. Lipid peroxide concentrations were measured as a thiobarbituric acid-reactive substance. Although arterial oxygen and carbon dioxide pressures and water content after 6 hours of preservation followed by reperfusion were similar in both the lazaroid and dexamethasone groups, lipid peroxide concentration was significantly higher in the dexamethasone group (0.88 +/- 0.07 mumol/gm) than in the lazaroid group (0.54 +/- 0.07 mumol/gm) (p < 0.01). After 12 hours of preservation, there were significant differences between the lazaroid and dexamethasone groups in arterial oxygen pressure (339 +/- 70 vs 27 +/- 3 mm Hg, p < 0.01), arterial carbon dioxide pressure (24.3 +/- 2.7 vs 47.7 +/- 7.0 mm Hg, p < 0.001), and lipid peroxide concentrations (0.69 +/- 0.07 vs 1.30 +/- 0.09 mumol/gm, p < 0.001). We conclude that addition of U74500A to the flush and storage solution enhances the preservation of the pulmonary graft in this transplant model.

Adenosine↗
PubMed1989

Microsomal cytochrome P-450-linked monooxygenase systems and lipid composition of human hepatocellular carcinoma.

The tissues of hepatocellular carcinoma were operatively resected from six patients. All four components of the systems of microsomal cytochrome P-450-linked monooxygenase of the tissues were investigated and compared to those of normal liver tissue. The concentrations of cytochromes P-450, P-420 and b5 were measured optically and the concentrations of all components except cytochrome P-450 were measured by the Western blotting method followed by immunochemical staining. In microsomes of hepatocellular carcinoma tissues, there was as much cytochrome P-450 and other redox components as in the normal liver tissues, but cytochrome P-450 in liver cancer tissues was unstable and easily converted to cytochrome P-420. The specific activities of NADPH- and NADH-ferricyanide and cytochrome c reductase of each sample were also measured. In the microsomes of the cancer tissues, the specific activities were remarkably reduced compared with those of normal liver tissues. The lipid compositions of the microsomes and the phospholipid/cholesterol ratios (w/w) were 13.1 +/- 3.13 in the cancer tissues and 43.0 +/- 6.74 in normal liver tissues. This difference of the lipid composition elucidates the instability of cytochrome P-450 molecules and the inefficiency of the electron transport of cytochrome P-450-linked monooxygenase systems.

Carcinoma, Hepatocellular↗