Survival of human carrier erythrocytes in vivo.

Erythrocytes offer the exciting opportunity of being used as carriers of therapeutic agents. Encapsulation within erythrocytes will give the therapeutic agent a clearance equivalent to the normal life of the erythrocyte therefore maintaining therapeutic blood levels over prolonged periods and also giving a sustained delivery to the monocyte-macrophage system (reticulo-endothelial system). Both the dose and frequency of therapeutic interventions could thus be reduced. Ensuring a near-physiological survival time of carrier erythrocytes is essential to their successful use as a sustained drug delivery system, and this has not been demonstrated in man. In this study we assessed the survival in vivo of autologous unloaded energy-replete carrier erythrocytes in nine volunteers, using a standard 51Cr erythrocyte-labelling technique. Within 144 h after infusion there was a 3 to 49% fall in circulating labelled cells, followed thereafter by an almost complete return to initial circulating levels; surface counting demonstrated an initial sequestration of erythrocytes by the spleen and subsequent release. Mean cell life and cell half-life of the carrier erythrocytes were within the normal range of 89 to 131 days and 19 to 29 days respectively. These results demonstrate the viability of carrier erythrocytes as a sustained drug delivery system.

Pulmonary dysfunction associated with cardiopulmonary bypass: a comparison of bubble and membrane oxygenators.

Intrapulmonary shunting and white cell sequestration in the lungs were compared prospectively in patients who underwent coronary artery grafting using either bubble or membrane oxygenators. Bubble oxygenators caused more sequestration of white cells, but this was not reflected in any detectable increase in pulmonary shunting. Postoperative blood loss was less in those patients who had been on membrane oxygenators. We conclude that there is little advantage in using the membrane oxygenator for uncomplicated short-term perfusions.

The haemoglobinopathies in Barbados (abstract only)

There is evidence to suggest that persons possessing the sickle cell gene is protected against falciparum malaria. A University College of the West Indies Survey was conducted in Barbados to determine the incidence of the abnormal haemoglobins with particular reference to the sickling gene and the findings compared with those in Jamaica. The genital implications are discussed, particularly the role of sickle cell anaemia itself and the findings in people from other Caribbean islands included for comparison (AU)

The aplastic crisis in sickle-cell anaemia

Of 12 patients with aplastic crisis associated sickle-cell disease, eleven were children with sickle-cell anaemia, and one was an adult with sickle-cell haemoglobin-C disease. Ten of the cases were seen over a period of less than 7 months, and the syndrome may be commoner than has previously been supposed. Evidence is given to support the hypothesis that the distribution of sickle-cell and foetal haemoglobins in the erythrocytes in sickle-cell anaemia is not homogeneous. The fact that seven of the cases belonged to three families implies that infection may play an important aetiological role. This view is supported by the clinical presentation, and by the fact that one patient apparently had infectious mononucleosis. Bacterial and viral studies fail to demonstrate any aetiological agent in these cases (Summary)