Early detection of graft failure using the blood metabolic profile of a liver recipient.

In this case report we describe the blood metabolic profile ("metabolomics") by nuclear magnetic resonance (NMR) spectroscopy and principle component analysis (PCA) from a patient who underwent two consecutive liver transplantations. The first graft from a living-related donor failed and was followed by a second successful transplant from a deceased donor. Using quantitative high-resolution H-NMR spectroscopy, 48 endogenous metabolites were analyzed in whole blood samples at baseline and different time points after each transplantation. From 48 analyzed metabolites, six metabolites were identified by PCA as metabolic markers consistent with a non-functional liver after first transplantation. Importantly, this distinctive metabolic profile was present as early as two hours after first transplant surgery when no other variable or conventional laboratory tests indicated poor graft function. This article reports the potential usefulness of quantitative H-NMR based metabolomics to diagnose early graft dysfunction in liver transplantation.

Ischemia-reperfusion injury is more severe in older versus young rat livers.

BACKGROUND: Hepatic warm ischemia during surgery remains a significant problem, particularly in organs with possible baseline dysfunction. The objective of this study was to investigate whether age influences the degree of warm ischemia-reperfusion injury in rat livers. MATERIALS AND METHODS: The left and median lobes of young (3 months) and adult (9 months) male rats were exposed to 75 min of ischemia followed by reperfusion. Each age group was divided into two sub-groups. One sub-group was observed for 8 h, whereas the other was allowed to survive. Animals in the 8-h groups (young and adult) were sacrificed, and blood and tissue were taken to determine liver enzymes, neutrophil accumulation, and blood metabolic profiles and to examine the histology. RESULTS: Hepatocellular injury was significantly greater in adult rats after 8 h of reperfusion, as determined by hepatic enzyme levels and histology. Liver enzyme levels were massively elevated in adult rats and were significantly higher compared with those of young rats. The degree of necrosis and neutrophil accumulation was significantly higher in adult rats. After 8 h of reperfusion, the metabolic profiling of the blood revealed elevated levels of creatine, creatinine, allantoin, and amino acids (tyrosine, methionine) in the adult rats. At 24 h of reperfusion, all adult rats died, in contrast to young rats, which all survived. CONCLUSIONS: Aging in rats is associated with greater hepatocellular injury and poor survival rate after 75 min of warm hepatic ischemia.

Mild hypothermia protects obese rats from fulminant hepatic necrosis induced by ischemia-reperfusion.

BACKGROUND: Obese Zucker rats demonstrate increased susceptibility to hepatic ischemia-reperfusion injury. This study evaluates the effect of mild systemic hypothermia on ischemia-induced acute fulminant necrosis during warm ischemia and reperfusion, and investigates blood metabolic profiles under normothermic and mildly hypothermic conditions. METHODS: The left and median hepatic lobes of male, obese, Zucker rats were exposed to 75 minutes of ischemia under either normothermic (36.9 +/- 0.3 degrees C) or mildly hypothermic (33.3 +/- 0.1 degrees C) conditions followed by 8 hours of reperfusion. Animals were killed and tissue and blood were harvested for analysis of histology, liver enzymes, and metabolic 1H-NMR spectroscopy. RESULTS: Liver enzyme activities were significantly higher in the normothermic group when compared with mildly hypothermic animals. Histologic analysis showed greater than 75% necrosis in the normothermic group, whereas in the mildly hypothermic group necrosis was less than 25%. Blood from normothermic animals contained greater concentrations of lactate (190%, P = .001) and lower concentrations of glucose (60%, P = .01) than hypothermic animals; hepatic osmolyte betaine was also increased in blood from the normothermic group (220%, P = .0002). In addition, normothermic rats had increased concentrations of circulating fatty acids, triglycerides, glutamate, succinate, and acetate when compared with the hypothermic. CONCLUSION: Mild hypothermia decreased hepatic necrosis in obese rats. NMR blood profiles indicate that hypothermia protects hepatic metabolism.

Mild hypothermia reduces the inflammatory response and hepatic ischemia/reperfusion injury in rats.

BACKGROUND/AIMS: Hypothermia is known to protect against ischemia/reperfusion (I/R) injury. The mechanisms of protection are incompletely understood and a temperature threshold for protection has not been established. METHODS: In anesthetized Wistar rats, partial (70%) hepatic ischemia was applied for 45 min. Three study groups were used. Group T31 (n = 6) spontaneously cooled to 31.3 +/- 0.8 degrees C, while group T34 (n = 6) spontaneously cooled to 34 degrees C and was then maintained at 34.0 +/- 0.1 degrees C using a heat lamp. The normothermic group (T37, n = 6) was maintained at 37.1 +/- 0.3 degrees C. Hepatic injury, inflammation, lipid peroxidation and metabolic function (using quantitative 1H-NMR) were assessed 24 h after reperfusion. RESULTS: At 24 h following reperfusion, alanine aminotransferase and aspartate aminotransferase increased to 5101 +/- 2378 and 6409 +/- 4202 U/l in the normothermic T37 group (P < 0.05 vs. T34 and T31), whereas transaminases in hypothermic groups (T31 and T34) were significantly lower. Severe liver necrosis was only noted with T37. Myeloperoxidase activity was increased in the T37 group when compared with hypothermic groups (223 +/- 161 (T37) vs. 16 +/- 10 (T31) and 8 +/- 5 (T34) mU/min/mg of tissue, P<0.05 vs. T31 and T34). 1H-NMR analysis of the blood of normothermic animals revealed metabolic changes consistent with increased ischemic injury, which was almost completely ameliorated in T34 and T31 groups. CONCLUSIONS: Mild hypothermia of 34 degrees C is sufficient to reduce I/R injury by inhibiting the inflammatory response. Further spontaneous cooling to 31 degrees C did not demonstrate any additional protective effect.