Combined effects of fasting and alanine on liver function recovery after cold ischemia

Assessment of a chloride-poor versus a chloride-containing version of a modified histidine-tryptophan-ketoglutarate solution in a rat liver transplantation model

Recent in vitro studies of cold-induced cell injury have revealed the detrimental effects of extracellular chloride on cold-stored isolated rat hepatocytes; however, its influence on endothelial cells is beneficial. To determine which of these effects is predominant in vivo, we tested both a chloride-poor variant of a new histidine-tryptophan-ketoglutarate (HTK)-based preservation solution and a chloride-containing variant in a rat liver transplantation model. The study, which was carried out in a blinded fashion with 7 or 8 rats per group, was divided into 2 parts: (1) a comparison of survival in 3 series under different conditions [different microsurgeons, rat strains, cold ischemia times (3, 12, and 24 hours), and warm ischemia times] and (2) an assessment of the microcirculation (30-90 minutes after reperfusion), laboratory data, bile production, and histology. In each of the survival experiments, a (strong) tendency toward prolonged survival was observed with the new chloride-containing solution (50% versus 12.5%, 75% versus 37.5%, and 100% versus 71.4% [chloride-containing vs. chloride-poor], overall P < 0.05). Additionally, the sinusoidal perfusion rates (83.9% ± 4.0% versus 69.2% ± 10.8%, P < 0.01) and the red blood cell velocities in sinusoids (147.7 ± 26.7 versus 115.5 ± 26.0 μm/second, P < 0.05) and in postsinusoidal venules (332.4 ± 87.3 versus 205.5 ± 53.5 μm/second, P < 0.01) were clearly higher with chloride. Moreover, the serum activities of liver enzymes were slightly reduced (not significantly), and bile production was significantly increased. These results suggest an overall beneficial effect of chloride in HTK-based liver preservation solutions.

Effects of fasting on hematologic and clinical chemical values in cynomolgus monkeys (Macaca fascicularis)

BACKGROUND

Fasting is an important pre-analytical factor that may affect clinical pathology parameters in toxicological and pharmacological studies. Little information is available on how fasting affects clinical pathology parameters in cynomolgus monkeys (Macaca fascicularis).The aim of this study was to evaluate the influence of fasting on clinical pathology parameters in healthy adult cynomolgus monkeys.

METHODS

Five female and six male cynomolgus monkeys were fasted for 0, 8, 16, and 24 hours. Changes in body weight (BW), core hematologic, and serum clinical chemical parameters were evaluated.

RESULTS

The BW significantly decreased after 24 hours of fasting. Significant decreases in red blood cell count, hemoglobin, hematocrit, and mean corpuscular volume and increases in mean cell hemoglobin and mean cell hemoglobin concentration were observed at 16 hours in males. In females, increasing the duration of fasting caused a significant time-dependent increase in platelets. Blood urea nitrogen showed significant decreases in female and male monkeys after fasting. Alkaline phosphatase increased in females after fasting. Aspartate transaminase significantly increased both in females and males at 8 hours. In females, alanine transaminase and lactate dehydrogenase significantly increased at 8 hours. Albumin significantly decreased in males 24 hours, but increased in females 16 hours after fasting. Serum glucose and triglyceride were not affected by fasting. Serum calcium decreased and inorganic phosphorus increased in males after fasting.

CONCLUSION

These results suggested that clinical pathology data would vary after fasting. The decision to feed or fast before blood collection for clinical pathology tests should be made based on careful consideration.

Attenuated cold storage injury of rat livers using a modified HTK solution

BACKGROUND

Preservation injury is a main factor leading to graft failure in liver transplantation. The aim of the study was to minimize preservation injury by modifications of the histidine-tryptophan-ketoglutarate (HTK) solution (incorporation of N-acetyl-histidine, aspartate, glycine, alanine, and arginine).

MATERIALS AND METHODS

The study was carried out in rats and subdivided into four parts. (1) Systemic toxicity of the modified HTK solution in comparison to the standard HTK solution was tested. (2) Hemodynamic and microcirculatory parameters were analyzed after i.v. injection of the respective solution. (3) Preservation injury after cold storage for different periods of time was assessed microscopically. (4) Reperfusion injury was analyzed in the isolated perfused liver by enzyme release and bile production.

RESULTS

Blood values, hemodynamic and microcirculatory parameters after i.v. and i.p. application did not significantly differ from control. The modified HTK solution led to an attenuated preservation injury after cold preservation for 24 h compared with standard HTK solution. There was a significantly decreased lactate dehydrogenase release after ischemia for 72 h and reperfusion using the modified solution. After 24 h cold storage and reperfusion the apoptosis index was reduced and bile production significantly increased.

CONCLUSION

Optimizing the HTK solution may be a promising therapeutic strategy for attenuation of cold storage injury.

Preoperative fasting: an outdated concept?

Recent studies have shown that fasting during the preoperative period for elective surgery induces a metabolic state that seems unfavorable for patients. Results from animal studies indicate that rapid depletion of liver glycogen before surgery leads to mobilization of muscle glycogen after surgery, in turn leading to reduced muscle strength. Depletion of liver glycogen also influences the function of the mononuclear phagocytic system (MPS), which is located predominantly in the liver. The MPS is essential in restricting endotoxin, which may translocate from the gut. In addition, surgery per se puts a substantial physical strain on the patient, and fasting may adversely affect the metabolic response to surgery. This paper presents experimental and clinical data that, when combined together, prove that fasting before surgery has adverse consequences for the patient.

New Insights into the Cellular and Molecular Mechanisms of Cold Storage Injury

Solid organ grafts, but also other biologic materials requiring storage for a few hours to a few days, are usually stored under hypothermic conditions. To decrease graft injury during cold storage, organ preservation solutions were developed many years ago. However, since then, modern biochemical and cell biologic methods have allowed further insights into the molecular and cellular mechanisms of cold storage injury, including further insights into alterations of the cellular ion homeostasis, the occurrence of a mitochondrial permeability transition, and the occurrence of free–radical-mediated hypothermic injury and cold-induced apoptosis. These new aspects of cold storage injury, which are not covered by preservation solutions in current clinical use and offer the potential for improvement of organ and tissue preservation, are presented here.