Hemoglobin solutions in experimental cardioplegia.

The addition of stroma-free hemoglobin solution to a standard St. Thomas Hospital cardioplegic solution significantly protected the heart from ischemic damage compared to the effect of the same solution without added hemoglobin. An experimental model of rat heart cardioplegia and transplantation comprising heart arrest for three hours at 20 degrees C was used.

Hydrodynamic instability of "stroma-free" hemoglobin.

A simple kinetic test with visual observation of hemoglobin solutions under 4 - 10x magnification was used to detect and roughly characterize a rapid formation of fine fibrous inhomogeneities in agitated "stroma-free" hemolyzates (SFH). In parallel SFH samples stored motionless for months, no such precipitate was observed. Hydrodynamic conditions are necessary to provoke a stepwise aggregation of small amounts of unstable filamentous nonhemoglobin molecules originating mostly from the stromata of erythrocytes and from constituents of other lysed blood cells.

Trends in exploitation of packed red blood cells.

The following trends aim to a more efficient exploitation of packed red blood cells (PRBC): 1. Improvement of the operative distribution of PRBCs for transfusions before expiration. 2.

Haemoglobin solutions: reversibly bound oxygen and its effect upon the hypoxic heart.

Stroma-free solutions of human haemoglobin modified with pyridoxal-5-phosphate, glutaraldehyde, borohydride and serum albumin were injected into the artery of an isolated rat heart perfused with Krebs-Henseleit solution under hypoxic conditions. About 70% of the oxygen transported by the modified haemoglobin was found to be utilized for a marked increase in the force of heart contraction. The results were in general correlation to the analysis of oxygenation curves of haemoglobin samples under study and confirmed the oxygen offloading ability.

On the question of lowering the content of ferrihaemoglobin in infusable haemoglobin solutions.

The reducing effect of ascorbic acid and of borohydride upon ferrihaemoglobin present in native and chemically modified human and bovine stroma-free hemoglobins was investigated. Ferrihaemoglobin which had been freshly prepared from oxyhaemoglobin by treatment with potassium ferricyanate was fully reduced to ferrohaemoglobin. Full reduction of ferrihaemoglobin, however, could not be achieved with those haemoglobin samples which had a partially deteriorated conformation due to long time storage or chemical modification.

Haemoglobin lyophilized with sucrose: the effect of residual moisture on storage.

Sucrose is one of the most effective substances which protect haemoglobin from spontaneous methaemoglobin formation during lyophilization and subsequent storage. The dry haemoglobin-sucrose system was treated under different conditions of temperature (up to 85 degrees C), time of storage (up to 6 years) and residual moisture (less than 0.1-7.