[Possibilities and limits of temporary liver substitution by hemoperfusion with biological material]. / Möglichkeiten und Grenzen des temporären Leberersatzes durch Hämoperfusion mit biologischem Material.

For temporary hepatic assistance we used 200 g porcine liver pieces (5 X 5 X 5 mm3) which were perfused for 6 h with 11 swine blood. ATP and energy reserve values reached their maxima 30 min after starting perfusion, remained unchanged for 120 min, and decreased thereafter. Following 30 min of perfusion energy charge values increased from 0.260 +/- 0.110 mumol/g to 0.560 +/- 0.093 mumol/g (normal value; 0.854 +/- 0.022 mumol/g) and thereafter remained unchanged for 6 h. These results suggest that good energy regulation was maintained in the liver pieces. The small liver cubes showed excellent ammonia and phenol detoxication. However, the liver pieces were not found to be able to conjugate serum bilirubin, which might have been caused by a lack of this anatomic pathway in our model. Levels of hepatic and lytic enzymes in the perfusate increased with the time of perfusion, though they were relatively low as compared to levels in patients with acute hepatic failure. The concentration of free fatty acids in the perfusate, which are known to potentiate hepatic coma, increased slightly. However, methyl mercaptane remained constant during perfusion. Concentrations of nearly all amino acids rose during 6-h perfusion due to damage of hepatic tissues, but the molar ratio of the branched chain amino acid to aromatic amino acid was not changed. These results suggest that liberated substances from the damaged liver would not potentiate hepatic encephalopathy. We feel that hemoperfusion over small liver pieces could be a useful method for hepatic assistance.

Comparison of a charcoal sorbent fiber with commercial charcoals for hemoperfusion.

A charcoal sorbent fiber (Enka, F.R.G.), was assessed for impurities, surface area, and adsorptive properties of its native charcoal, and compared with other uncoated activated charcoals. In vivo and in vitro hemocompatibility of the fiber were assessed as well as the adsorptive properties for endogenous toxins. The charcoal of the fiber had few impurities and a high surface area of 1,200 m2/g charcoal. For measuring the adsorptive speeds, 2 g of the uncoated charcoals were milled and screened to a particle size of 150-250 microns (Enka; 30-40 microns) and then mixed with the solutions of the individual solutes. The charcoal types of Enka, used in the charcoal sorbent fiber, and of Sutcliffe Speakman, used in the acrylic hydrogel coated charcoal, exhibited the highest adsorptive rates for bromthalein (middle molecular weight marker) and inulin (high molecular weight marker). No hematological differences among the various charcoals were found during the in vivo hemoperfusions. In the in vitro hemoperfusions with heparinized fresh blood, the fibers showed the lowest loss of leucocytes and thrombocytes. In the in vitro evaluation of the absorbents for hepatic support, the charcoal fiber and the petroleum pitch charcoal of Asahi had the best adsorptive properties for substances in the low molecular weight range.

Early metabolic disturbances in the liver following unilateral hepatic or common bile duct obstruction in rabbits.

The early metabolic disturbances in the liver following ligation of the left hepatic or the common duct were studied in the rabbit. In the rabbits subjected to ligation of the left hepatic bile duct, the phosphorylative activity of the liver mitochondria in the ligated lobe decreased to about 50% of controls 48 h after the ligation, while that in the nonligated lobe increased 2-fold. These rabbits continued to live. On the other hand, in the rabbits subjected to ligation of the common bile duct, the mitochondrial phosphorylative activity increased slightly at 3 h after the ligation but fell rapidly thereafter. The mitochondrial free NAD+ to NADH ratios and hepatic energy charge (ATP+1/2ADP/ATP+ADP+AMP) markedly decreased after the ligation. Most of these rabbits did not survive over 2 days. These results indicate that the metabolic disturbances in the jaundiced liver are due to an impairment of the oxidative phosphorylation. In addition, it is suggested that the maintenance of the energy balance by enhanced mitochondrial phosphorylative activity is readily impaired in the jaundiced liver.

[Prolongation of ischemic tolerance time of donor livers by alkaline preservation solutions]. / Verlängerung der Ischämietoleranzzeit der Spenderleber durch alkalinisierte Konservierungslösungen.

Intracellular enzyme activities can be greatly influenced by alterations of pH, and non-physiologic pH may inhibit cell metabolism. The study was undertaken to examine the influence of pH values in preservation solution on ischemic tolerance time of the liver. BDE rat livers were used. Livers were preserved for 20 min or 2 h in warm ischemia after an initial perfusion with Ringer's solution at pH 9.0, 7.4, and 6.0. The values of total adenine nucleotide (TAN) and energy reserve (ER) in the livers were determined at the end of the preservation. After 20 min of warm ischemia, TAN values at pH 9.0 and 7.4 fell to 2.727 +/- 0.255 and 2.410 +/- 0.164 mumol/g, respectively (normal values: 3.414 +/- 0.270 mumol/g) and ER values to 0.786 +/- 0.186 mumol/g at pH 9.0 and to 0.446 +/- 0.095 mumol/g at pH 7.4 (normal values: 2.962 +/- 0.214 mumol/g). A similar trend was also observed after 2 h of warm ischemia. The preservation with a solution at pH 6.0 did not present any difference as compared to that at pH 7.4. Four-hour preservation in cold ischemia with Ringer's solution at pH 9.0 rendered higher values of TAN (2.635 +/- 0.085 mumol/g) and ER (0.336 +/- 0.026 mumol/g) than those in preservation at pH 7.4. No significant difference between TAN and ER values was found when 4-h preservation at pH 7.4 and 6.0 was compared. In another group an intermittent liver perfusion at 1-h interval was performed with chilled Ringer's solution; afterwards GOT, GPT, beta-glucuronidase, and acid phosphatase values in the effluents were evaluated. All of these enzymes showed higher concentration in the effluent with solution at pH 7.4 than that at 9.0. These results suggested that better intracellular energy reserve and organ viability can be maintained by preservation with alkaline solution. Furthermore, ER values seemed to be an excellent indicator of the organ viability during preservation. These were also confirmed by orthotopic hepatic transplantation in pigs. Livers were successfully preserved with alkaline Ringer's solution for up to 12 h. However, without change of pH, livers could not be preserved for more than 4.5 h.