HISTORY

MESED was initially developed to obtain a known amount of nearly pure erythrocytes from blood, without disturbing their natural environment. Red-cells make up ca 45% of any blood volume whereas ca 55% of blood corresponds to plasma. Measuring off a sediment of erythrocytes in sample pretreatment RELIABLY without MESED is impossible. As a consequence the amount of a substance on erythrocytes mostly has been neglected because of the un-fit initial separation procedure.

Our understanding of a disease process or drug effect hence is mainly based on observations in plasma. However the amount of a substance on erythrocytes frequently has no linear relationship with the amount in plasma. This is especially true for lipophylic compounds, e.g. fatty acids. Sometimes a substance hardly can be detected in plasma and is only present in erythrocytes. Secondly, as proteins in plasma become saturated erythrocytes transport disproportionately more. The transport to the vascular  endothelium from the cell fraction then is much faster than that from plasma and the equilibrium between erythrocytes and vascular endothelium becomes a driving force. (For instance protein binding will be easily saturated at intravenous (bolus) administration and transport of substances from blood to tissues resides mainly in the plasma water and erythrocyte fractions. The concentrations in these fractions are however unknown.)

Apart from its value in biosciences MESED is used in the food and oil industry. Viscous liquids cannot be measured off by a pipette. In the surveillance of industrial processes and in chemical technology on a laboratory scale, the instrument is practical.