Hemodilution with liposome-encapsulated low-oxygen-affinity hemoglobin does not attenuate hypothermic cerebral ischemia in rats.

Hypothermia decreases cerebral metabolism and increases hemoglobin oxygen affinity. A hypothesis that the reversal of increased oxygen affinity would further attenuate hypothermic cerebral ischemia was tested by evaluating the effects of liposome-encapsulated hemoglobin (LipoHb) with low oxygen affinity (P50 = 40-50 mmHg) on hypothermic incomplete cerebral ischemia. Wistar rats were randomly assigned to one of the following two groups: (A) exchange transfusion with LipoHb solution (Hb = 6 g/dl) (LipoHb, n = 5), (B) no exchange transfusion (control, n = 5).

Hemodilution with liposome-encapsulated low-oxygen-affinity hemoglobin facilitates rapid recovery from ischemic acidosis after cerebral ischemia in rats.

Liposome-encapsulated hemoglobin (LipoHb) with low oxygen affinity (P(50) = 40-50 mmHg) has been developed. The purpose of this study was to evaluate the effects of the LipoHb on incomplete cerebral ischemia. Wistar rats were randomly assigned to one of the following three groups: (A) exchange transfusion with LipoHb solution (Hb = 6 g/dl) (LipoHb, n = 7), (B) exchange transfusion with rat red blood cell (RBC) solution (Hb = 6 g/dl) (RBC, n = 7), (C) no exchange transfusion (control, n = 7).

Optimized retrograde cerebral perfusion reduces ischemic energy depletion.

It has been reported that retrograde cerebral perfusion (RCP) provides minimal capillary flow; however, the extent to which RCP can provide aerobic metabolic support is unknown. We evaluated whether perfusate composition optimization for RCP would preserve brain energy metabolism during hypothermic circulatory arrest (HCA) at 20 degrees C in rats. Three types of perfusates were prepared: hemoglobin-free saline, rat red blood cells, and artificial blood substitute (liposome-encapsulated hemoglobin); perfusates were made hypertonic, cooled to 20 degrees C, and oxygenated and CO(2) was administered (pH-stat management).

Difference in the cardioprotective mechanisms between ischemic preconditioning and pharmacological preconditioning by diazoxide in rat hearts.

Background: Recent studies have implicated the opening of mitochondrial K(ATP) (mitoK(ATP)) channels and the production of reactive oxygen species (ROS) in the cardioprotective mechanism of ischemic preconditioning (IPC).

Methods And Results: The involvement of mitoK(ATP) channels and ROS in the cardioprotective effects of both IPC and the mitoK(ATP) channel opener diazoxide (DZ) was investigated in ischemic/reperfused rat hearts. The effects of IPC and DZ on myocardial high-energy phosphate concentrations and intracellular pH (pH(i)) were also examined using (31)P nuclear magnetic resonance spectroscopy.

Liposomal photofrin enhances therapeutic efficacy of photodynamic therapy against the human gastric cancer.

Photodynamic therapy (PDT) has been established as a potent and less invasive treatment for gastrointestinal tumors. The aim of the present study was to investigate whether or not liposomalization of the photosensitizer enhanced the therapeutic efficacy of PDT. Photofrin (PF) was entrapped in multilammelar liposomes.

Protective effects of hydrogen peroxide against ischemia/reperfusion injury in perfused rat hearts.

Among the several mechanisms proposed for ischemic preconditioning (IPC), generation of reactive oxygen species (ROS) is reported to be involved in the cardioprotective effects of IPC. The present study was designed to investigate whether repetitive exposure to hydrogen peroxide (H(2)O(2)) can protect the myocardium against subsequent ischemia/reperfusion injury, and whether the H(2)O(2)-induced cardioprotection is related to the preservation of energy metabolism. Langendorff-perfused rat hearts were exposed to two, 5 min episodes of IPC or to various concentrations of H(2)O(2) twice and then to 35 min global ischemia and 40 min reperfusion.