Allopurinol and xanthine oxidase inhibition in liver ischemia reperfusion.

Introduction: Allopurinol was first introduced, in 1963, as a xanthine oxidase inhibitor when it was investigated for concomitant use with cancer chemotherapy drugs. Today it is used in gout and hyperuricemia. Due to its additive benefit in preventing oxidative damage, attention has shifted towards the use of allopurinol in organ ischemia and reperfusion.

Effects of dantrolene on ischemia-reperfusion injury in animal models: a review of outcomes in heart, brain, liver, and kidney.

Background/objectives: Ischemia-reperfusion (IR) is the restoration of blood flow to a tissue that was formerly deficient of blood flow. Tissue damage after IR is considered an IR injury (IRI). During IR, there is an increased level of cytosolic calcium ([Ca(2+)]i) due to the release of calcium from mitochondrial, sarcoendoplasmic reticulum, and nuclear organelles.

Inflammatory mediators of liver ischemia-reperfusion injury.

Liver ischemia and reperfusion--which cause liver damage that is significant in a variety of diseases, injuries, and procedures (including but not limited to trauma and transplant)--have been the focus of many investigations in recent years. Although the mechanisms of ischemia-reperfusion injury are numerous and complex, many advances in treatment have been made. The following review considers recent advances in the understanding of hepatic ischemia-reperfusion injury and focuses on inflammatory mediators of significance.

Nitric oxide mechanism of protection in ischemia and reperfusion injury.

In 1992 nitric oxide (NO) was declared molecule of the year by Science magazine, and ever since research on this molecule continues to increase. Following this award, NO was shown to be a mediator/protector of ischemia and reperfusion injury in many organs, such as the heart, liver, lungs, and kidneys. Controversy has existed concerning the actual protective effects of NO.

Protein kinases in organ ischemia and reperfusion.

There is ample evidence of the role that protein kinases play in the signaling pathways secondary to ischemia and reperfusion (I/R). The protein kinases initiate several interconnected downstream cascades regulated by phosphorylation and dephosphorylation reactions. The signaling transduction pathways ultimately initiate the nuclear transcription of the inflammatory and anti-inflammatory genes to repair and assist in the recovery of damaged cells.

Evaluation of a novel cold storage solution (HBs) in a rat kidney transplant model.

We developed an improved solution for hypothermic storage (0-4 degrees C) of kidneys. The cold storage solution (HBS) was composed of macromolecules, high-energy cellular substrates, and a mixture of antiproteolytic amino acids, antioxidants, and anti-inflammatory compounds. The objectives in developing this solution were to achieve superior metabolic support of the kidney during cold storage and to protect against ischemic injury.

Ryanodine receptor antagonism protects the ischemic liver and modulates TNF-alpha and IL-10.

Background: Dantrolene is a ryanodine receptor and intracellular calcium antagonist. The ryanodine receptor (RyR) Ca(2+) release channel mobilizes Ca(2+) from internal stores to support a variety of cellular functions, including the inflammatory response after ischemia and reperfusion. The pharmacological mechanism of dantrolene is associated with the inhibition of the release of Ca(2+) from the skeletal muscle sarcoplasmic reticulum (SR).

Anti-ischemic effect of selectin blocker through modulation of tumor necrosis factor-alpha and interleukin-10.

Background: Preliminary studies in our laboratories indicate that a recently discovered synthetic drug, TBC-1269, acts as a multiple selectin blocker and provides protection against tissue damage in rats that are subjected to severe liver ischemia/reperfusion. Here, we report that this effect is dose and time dependent, with its effects acting through the modulation of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10.

Material And Methods: Mice subjected to 90 min of partial (70-80%) hepatic ischemia and 3 h of reperfusion were divided into eight groups (n=6/group): sham, ischemic control (IC), three groups of TBC-1269-treated animals at different concentrations (10, 20, 40, mg/kg) and another three groups of TBC-1269 given at 40 mg/kg at different times of administration: 15 min prereperfusion but after ischemia (no pretreatment), at the time of reperfusion, and at 15 min after reperfusion.

Selectin inhibition modulates NF-kappa B and AP-1 signaling after liver ischemia/reperfusion.

The infiltration of neutrophils after ischemia and reperfusion (I/R) is facilitated by the expression of adhesion molecules on the surface of both leukocytes and endothelial cells. Adhesion molecules of the selectin family are of particular importance at the onset of neutrophil mediated injury, as demonstrated by the occurrence of many cellular interactions with the final extravasation of inflammatory leukocytes at the site of I/R damage. Previous studies demonstrated a prevention of neutrophil extravasation and protection of ischemic damage when a small anti-selectin molecule was used.

Phosphoregulation of signal transduction pathways in ischemia and reperfusion.

Ischemia/reperfusion (I/R) injury triggered by pathogenic processes, such as organ transplant dysfunction, stroke, myocardial infarction, and shock, stimulate both immune and inflammatory pathways. Inflammatory cell activation and cytotoxic cytokine expression are associated with reperfusion injury. The activation of these inflammatory mediators initiates several interconnected downstream cascades regulated by phosphorylation and dephosphorylation reactions.

Molecular biology of apoptosis in ischemia and reperfusion.

This study reviews the current understanding of the mechanisms that mediate the complex processes involved in apoptosis secondary to ischemia and reperfusion (I/R) and is not intended as a complete literature review of apoptosis. Several biochemical reactions trigger a cascade of events, which activate caspases. These caspases exert their effect through downstream proteolysis until the final effector caspases mediate the nuclear features characteristic of apoptosis, DNA fragmentation and condensation.

Molecular signaling pathways in ischemia/reperfusion.

Ischemia and reperfusion (I/R) is an important pathologic phenomenon that has not been completely defined from the perspective of the molecular signaling pathways developed immediately at its inception to minutes and hours thereafter. From the practical point of view, we have divided I/R into 3 phases: phase I, which occurs seconds to minutes after the injury and is associated with changes dependent on the activation of phospholipases, intracellular calcium, eicosanoids, other lipid molecules, protein kinases, inducible nitric oxide synthase, and the expression of preformed adhesion molecules like P-selectin; phase II, which occurs minutes to hours after I/R injury and is associated with the active transcription of protein synthesis of molecules like inflammatory cytokines (mainly tumor necrosis factor-alpha and interleukin 1) starting their signaling downstream from the membrane into the cytoplasm where kinases will be activated and send signals to the nucleus for the activation of transcription factors and further continuing with the inflammatory event; and phase III, which occurs several hours to days after I/R and is associated with the appearance of molecular chronic mechanisms of protection like the presence of anti-inflammatory cytokines of the IL-10 type, late adhesion molecules, and other growth factors such as TGF-beta. This completes the whole molecular event related to I/R injury.

Xenotransplantation: a view to the past and an unrealized promise to the future.

Since the early 20th Century when Emerich Ullman transplanted a pig kidney into the arm of a woman (1902), Princeteau implanted portions of a rabbit kidney into the kidney of a child who was dying of renal insufficiency (1905), Jaboulay transplanted two kidneys from a pig and a goat as donor sources (1906), and Unger implanted a monkey kidney into a human (1910), xenotranplantation has made some strides, mostly related to advanced surgical techniques, improved knowledge of immunological principles, and to steps associated with the development of the most effective immunosuppressive therapy. Innovative surgical techniques were introduced by Alexis Carrel in the first decade of the 1900s, so that vascular anastomoses could be realized without a considerable amount of thrombotic/embolic problems, long before heparin times. Inasmuch as these advances were soundly characterized, it became evident that the results were far from expected and that the time was not ripe for xenotranplantation.

Selectin inhibition modulates Akt/MAPK signaling and chemokine expression after liver ischemia-reperfusion.

Tissue damage after ischemia and reperfusion (I/R) is largely caused by the sequelae of neutrophil infiltration. This inflammatory process can be initiated as the result of stroke, coronary ischemia, trauma, and other related conditions. The infiltration of neutrophils is facilitated by the expression of adhesion molecules on the surface of endothelial cells.

Reactive oxygen species and molecular biology of ischemia/reperfusion.

Ischemic reperfusion injury is a complex pathophysiological event associated with significant impairment of multiple vascular and cellular responses. Oxidative damage due to the presence of radical oxygen species is the essential step that initiates a wide range of intracellular stress signaling processes that culminate in excessive cytokine and chemokine response, adhesion molecule upregulation and nitric oxide overproduction. As we studied all the various mechanisms of injury, we began deciphering the best means to treat the ischemic insult by modulating those proteins or active mediators that are responsible for the lesion.

The role of MAP kinases in trauma and ischemia-reperfusion.

Mitogen-activated protein kinases (MAPKs) have been the focus of a number of studies, as these compounds are involved in a number of important inflammatory cell signaling mechanisms. Recent studies have further elucidated the role of MAPKs in the inflammatory response, as a result of trauma and/or ischemia-reperfusion (I/R) injury. There are three major classes of MAPKs that may be involved in the inflammatory response: extracellular signal-regulated kinases (ERKs), stress-activated protein kinases (SAPKs)/c-Jun NH(2)-terminal kinases (JNKs), and p38 MAPKs (p38).

Exogenous nitric oxide protects kidney from ischemia/reperfusion.

Blockade of NO production is followed by an increase in leukocyte rolling and adhesion resulting in some deleterious effects of ischemia. Preischemic administration of NO protects vascular integrity after reperfusion. Exogenous NO causes a direct reduction in leukocyte adhesion.

21-Aminosteroids block neutrophil infiltration and provide liver protection independent of NO2-/NO3- levels.

21-Aminosteroids are antioxidant compounds that prevent iron-dependent lipid peroxidation and improve cell viability. In this work we attempt to define the role of 21-aminosteroids in liver ischemia and reperfusion and assess their possible mode of action, specifically their effect on neutrophil infiltration and nitrite/nitrate levels. Total liver ischemia for 90 min was produced in the rat with the use of a portosystemic shunt.

Mechanism of protection of verapamil by preventing neutrophil infiltration in the ischemic rat kidney.

In this study, we tested if the mechanism of protection of a calcium channel blocker, Verapamil (VER), was due to modulation of neutrophil infiltration after ischemia/reperfusion injury, in a rat renal ischemic model. Forty-four Sprague-Dawley rats were subjected to 75 min of warm ischemia and immediate contralateral nephrectomy. The animals were divided into two groups: the ischemic control (IC) group, which received normal saline, and the experimental group that received VER 1.