Sialic acid-depleted red cells following acute myocardial infarction

A reduction of red cell SA in patients following acute myocardial infarction is reported and the effects of SA-depleted red cells on cardiac index and alveolar capillary blood flow in the dog are described. The mean red cell SA in 26 patients following acute myocardial infarction was 0.021 +/- 0.001 compared with a mean of 0.031 +/- 0.002 mumol./0.1 ml RBC in 12 normal subjects (p less than 0.01). In five dogs injected with neuraminidase, an enzyme which removes SA from the red cell membrane, a 43% decrease in mean cardiac index from 2.3 +/- 0.22 to 1.3 +/- 0.16 (p less than 0.01) occurred. In films of the pulmonary microcircuation the mean widths of typical alveolar capillary beds decreased 42.6% +/- 5% (p less than 0.01). In three other dogs, autotransfusion with SA-depleted stored blood resulted in a 25% decrease in mean cardiac index from 2.0 +/- 0.21 to 1.5 +/- 0.21 (p less than 0.2), and a 21.7% +/- 0.9% (p less than 0.01) decrease in mean widths of typical alveolar capillary beds. We conclude that a reduction of red cell SA follows acute myocardial infarction and that SA-depleted red cells decrease cardiac index and alveolar capillary blood flow in the dogs.     

Inhibition of iron absorption from human milk by baby food

We measured the effect of a common baby food, strained pears, on the absorption of iron from human milk. Five adult subjects were initially fed 1 dL of human milk that contained added ferrous citrate Fe 59; the same subjects were later fed human milk and one jar of baby food. Incorporation of 59Fe into RBCs averaged approximately one quarter of the administered iron from the human milk. When the milk was combined with the baby food, incorporation was significantly decreased. The addition of a supplemental food to the diet of the breast-fed infant impairs the bioavailability of the iron from human milk.