[Gaseous oxygen for protection and conditioning of organs during ischemia]. / Gasförmiger Sauerstoff zur Protektion und Konditionierung von Organen in Ischämie.

During organ ischemia, oxygen (O2) is the first "substrate", which is depleted. However, during ischemic storage in hypothermia (0-4 degrees C), a sufficient oxygenation is attainable by means of gaseous O2. The results of organ preservation were (mostly) better than those obtained with other methods at the respective times. O2 can be supplied via organ surfaces: Applying high O2-pressures (3040-15,200 hPa), ileum and lungs or hearts had some functions after 48 and 72 h storage, respectively; life-supporting functions regained kidneys and pancreas after 48 and 22 h storage, respectively. At normobaric conditions, intestine supplied with O2 via its lumen had during ischemic storage an aerobic metabolism and a better post-ischemic function. Using the "two-layer-method" (TLM), pancreas was stored for 96 h and after 90 min anaerobic warm ischemia (aWI) for 48 h with life-supporting functions after transplantation (Tx). Ischemic organs can be persufflated normobarically with gaseous O2 via their vessels. Hearts, skeletal muscles and kidneys in normothermia or frogs' spinal cords-remained viable for many hours. In hypothermia, kidneys damaged by 30 or 60 min aWI could be preserved for 48 and 24 h, respectively, with life-supporting functions after Tx. Hearts subjected to several hours of aerobic ischemia performed post-ischemically better. Livers aerobically stored for 48 h, or for 24 or 4 h after 30 or 60 min aWI, respectively, exhibited greatly improved post-ischemic functions. After 60 min aWI and 2 h persufflation for reconditioning, livers could be stored for another 22 h period of anaerobic ischemia. With normobaric O2-persufflation or TLM during ischemia, energy supply in form of ATP and its demand-meeting utilisation during hypothermia are apparently guaranteed, so that even longer periods of ischemia for Tx-related measures can be overcome. Not only the maintenance of cell and organ integrity or of cellular functions, but also the repair of damaged structures and functions have become possible with less expenditures and risks than with perfusion. The composition of the solutions for preservation or reconditioning of the ischemic organs is pivotal.

No beneficial effects of taurine application on oxygen free radical production after hemorrhagic shock in rats.

Oxygen free radical generation contributes to the reinfusion damage after hemorrhagic shock. Taurine has been proposed to have radical scavenging properties under certain experimental conditions. Therefore the present study was undertaken to investigate if taurine would be able to attenuate adverse effects of shock/resuscitation in male rats (fasted over night). Under pentobarbital anesthesia, hemorrhagic shock (HS) was induced for 1 h by bleeding of the animal [mean arterial blood pressure (MAP) = 40 mm Hg] followed by shed blood reinfusion and another 1 h period of resuscitation. Rats were divided into two groups: Treated rats (n = 6) were injected with taurine (40 mg/kg body mass) prior to withdrawal of shed blood; untreated rats (n = 9) received respective volumes of a normal saline solution. In untreated animals, free radical induced lipid peroxidation was documented by an increase of malondialdehyde (MDA) in the systemic circulation (nmol/ml; HPLC measurement) from 1.06 +/- 0.08 during normotension (NT) to 1.35+/- 0.18** 1 h after resuscitation (RS). Accordingly, plasma levels of alanine aminotransferase (ALT) (11 +/- 2; 35 +/- 12; 94 +/- 44 U/l, NT; HS; RS) and ammonia (120 +/- 39; 532 +/- 161; 224 +/- 101 micrograms/dl) changed significantly during the experimental protocol. Hepatic ATPase-content as an indicator of energetic status of the liver fell from 4.8 +/- 0.83 to 0.56 +/- 0.27 after HS and recovered to only 2.7 +/- 1.6 mumol/g after RS. Leukocyte infiltration of the liver was followed by tissue levels of myeloperoxidase (MPO) which did not change during HS, but rose during RS (37.9 +/- 18.5; 38.6 +/- 16.4; 77.5 +/- 24; arbitrary units), documenting an inflammatory reaction after HS. Taurine treated rats showed levels of MDA not different from untreated rats after RS; also no differences were observed concerning enzyme concentrations and ammonia levels. The liver tissue levels of ATP and MPO revealed no differences between the two groups during the various periods of the experiment. Liver tissue perfusion, as measured by Laser Doppler flowmetry, also did not show significant differences between both groups. MAP was significantly higher in the taurine-treated rats during the first 40 min of resuscitation. It is concluded that even a relatively high dose of taurine failed to attenuate the impact of oxygen free radicals and did not improve the recovery of the rats during the early resuscitation period.

Effect of glutamine or glucagon-insulin enriched total parenteral nutrition on liver and gut in 70% hepatectomized rats with colon stenosis.

BACKGROUND: Malnutrition of enterocytes is believed to facilitate the breakdown of the intestinal mucosal barrier, furthering a translocation of enteric bacteria with subsequent severe infection, which has been described after extensive hepatectomy. Glutamine and glucagon insulin are said to attenuate the malnutrition of enterocytes. To determine whether this was true, the effects on the remnant liver and the gut of total parenteral nutrition supplemented by admixtures of glutamine and/or glucagon insulin were investigated in rats subjected to massive hepatectomy and transient intestinal stasis. STUDY DESIGN: Rats underwent a permanent cannulation of the superior caval vein without restraining their mobility, a 70% hepatectomy, and a 24 hour string-ligation stenosis of the colon. A standard total parenteral nutrition solution was infused without or with 2% glutamine and without or with glucagon-insulin supplementation, respectively. RESULTS: Glutamine and glucagon-insulin supplemented total parenteral nutrition increased ileal mucosal DNA concentrations during and after intestinal stasis. Glutamine or glucagon-insulin alone had less pronounced effects. In the liver, the combined supplementation resulted in reduced adenosine triphosphate concentrations and increased mitochondrial adenosine triphosphate synthesis as well as in an early increase in DNA concentrations. CONCLUSION: Glutamine and glucagon-insulin enriched total parenteral nutrition attenuates malnutrition of enterocytes after massive abdominal stress and promotes liver regeneration after extensive hepatectomy.

Resuscitation of cadaveric livers from non-heart-beating donors after warm ischemic insult: a novel technique tested in the rat.

Clinical liver transplantation has become the therapy of choice in end-stage liver disease, but the limited availability of suitable donor organs still impedes its widespread application. In order to increase the availability of donor organs for liver transplantation, it would be advantageous if ischemically damaged livers could be resuscitated from cadavers in which the heart has stopped beating. A method for doing this has been developed in a rat model. Compared to livers excised from rats in which the heart is still beating, severe deteriorations of tissue integrity and functional performance were evident in predamaged livers after cold preservation without supplementary treatment. A treatment of those livers which included an antioxidant rinse with superoxide dismutase, and venous vascular insufflation of gaseous oxygen during preservation, completely prevented tissue alterations upon reperfusion, and promoted a functional recovery of the livers, making them comparable to organs harvested from heart-beating donors.

Long-lasting hypoxic preservation of porcine kidney cells. Beneficial effect of taurine on viability and metabolism in a simplified transplantation model.

Taurine administered during hypoxia reduced the cell damage due to O2 deficiency markedly. The beneficial effect outlasted the period of reoxygenation. The mechanisms for the improved survival rates are postulated in a reduced osmoregulatory disturbance of cellular integrity, improved Ca2+ homeostasis and induction of accelerated cellular growth processes. We conclude that taurine supplementation of the conventionally used kidney preservation solution (UW) improves this "gold standard" kidney preservation solution markedly.

Protective effect of taurine on hypoxia and reoxygenation-induced damage of human colon cells (HT 29).

In this experimental model, taurine administered during hypoxia markedly reduced the cell damage due to O2 deficiency, and the beneficial effect outlasted the period of reoxygenation. The mechanisms for the improved survival rates are postulated to be a reduced osmoregulatory disturbance of cellular integrity, improved Ca2+ homeostasis and induction of accelerated cellular growth processes. In our simplified cell culture model the UW solution seems to be the most appropriate solution for the cold (hypoxic) preservation of human colon cells. We conclude, that within this experimental model and under these experimental conditions, taurine supplementation of the conventionally used preservation solutions improved the solutions markedly. Considering our previous studies, taurine seems to be a potent endogenous protective agent against cellular deterioration due to hypoxia and reoxygenation.

Protecting effect of taurine against hypoxic cell damage in renal tubular cells cultured in different transplant preservation solutions.

We conclude that, within this experimental model and under these experimental conditions, taurine supplementation of standard kidney preservation solutions improves survival of kidney cells during hypoxic preservation. The protective effect depends on the taurine concentration, the hypoxic preservation time and the used preservation solution. Physiological taurine concentrations are effective during short hypoxic periods, whereas pharmacological taurine concentrations seem to be needed for longer periods of hypoxia. Within this experimental model University of Wisconsin solution seems to be more effective than Euro collins solution.

Evaluation of antioxidant treatment with superoxide dismutase in rat liver transplantation after warm ischemia.

In order to investigate the effects of the exogenously administered radical scavenger superoxide dismutase (SOD) on the orthotopic liver graft, livers from male Wistar rats were transplanted after subjection to 40 min of warm ischemia and 30 min of storage at 4 degrees C. SOD was given at the onset of ischemia and before reperfusion as a supplement (6,000 IU) to the washout solutions. 30,000 IU were infused into the recipient. SOD reduced tissue levels of thiobarbituric acid-reacting substances at the end of ischemia (737 vs. 956 nmol/g; p < 0.01) and 60 min after the onset of reperfusion (629 vs. 947 nmol/g; p < 0.001) and preserved total adenine nucleotides after reperfusion (11.69 vs. 10.40 mumol/g; p < 0.01). Survival 2 weeks after transplantation was 18% (2/11) in the SOD group versus 10% (1/10; nonsignificant) in untreated animals. It is concluded that SOD protects the ischemically altered liver from radical mediated peroxidation and preserves hepatic energy stores upon reperfusion. However, in our model no major improvement in organ viability could by achieved.

31P NMR spectroscopy for in vitro viability testing of porcine pancreatic islets.

The quality of pancreatic islets prepared by an intraductal pancreas collagenase perfusion technique was tested using three independent methods: 31P NMR spectroscopy, an insulin secretion test, and a staining method. The viability of pancreatic islet tissue was evaluated using the ratio of phosphate diester to phosphate monoester (PDE/PME) as a new criterion obtained by 31P NMR spectroscopy. According to this criterion, three types of tissue fragments could be characterized: vital (PDE/PME 0.5-0.9), damaged (PDE/PME less than 0.2), and necrotic (no PDE, no PME). The findings in the three different groups could be correlated to three trends of insulin secretion of the preparations following glucose challenge: good response to the glucose challenge, continuous decrease of insulin production, and no insulin secretion. We feel that 31P NMR spectroscopy offers a rapid and suitable method for classifying the viability of isolated pancreatic islets.