Beneficial effects of aggressive protein feeding in severely burned children.

To determine any potential benefit of feeding increased amounts of protein to hypermetbolic burned patients, 18 children with burns averaging 60% total surface area were randomized into two matched groups and studied serially for at least six weeks: the first group was given a normal diet with a balanced nutritional supplement, and the second group was supplemented with milk whey protein. The normal protein group received 87.1% of their desired caloric intake with 16.5% of calories from protein compared to 77.7% of desired caloric intake with 23.0% of calories from protein for the high protein group. Despite a higher caloric intake, the normal protein group had a worse opsonic index compared to the high protein group (0.42 +/- 0.04 vs. 0.62 +/- 0.05, p < 0.0007), lower levels of C3 (1371 +/- 55 vs. 1585 +/- 64 micrograms/ml, p < 0.01), lower levels of IgG (805 +/- 52 vs. 975 +/- 56 micrograms/ml, p < 0.03), lower levels of transferrin (200 +/- 10 vs. 283 +/- 18 mg/dl, p < 0.0001), lower levels of total serum protein (5.5 +/- 0.1 vs. 6.3 +/- 0.2 g/dl, p < 0.005), more bacteremic days (11% vs. 8%, p < 0.005) and worse survival (5/9--56% vs. 9/9--100%, p < 0.03). Patients receiving the high protein diet had significantly higher plasma levels of valine, lysine, threonine, leucine, aginine, isoleucine, proline, serine, asparagine, tryptophane, and tyrosine. Asparagine levels were significantly (p < 0.01) associated with better neutrophil function and opsonic index. Except for phenylalanine, significant associations were found for serum levels of each of the amino acids with concentrations of one or more serum proteins. These studies provide evidence that many immunologic functions are dependent upon optimal availability of specific amino acids, and that routine diets do not provide sufficient protein to satisfy the needs of seriously burned children.

Ultrastructural and chemical alteration of the cell envelope of Pseudomonas aeruginosa, associated with resistance to ethylenediaminetetraacetate resulting from growth in a Mg2+-deficient medium.

Cells of Pseudomonas aeruginosa became resistant to the lytic effect of ethylenediametetraacetate (EDTA) when grown in a Mg(2+)-deficient medium. To correlate ultrastructural changes in the cell wall associated with the shift to EDTA-resistance, a freeze-etch study was performed. Upon fracturing, the outer cell wall membrane split down the hydrophobic center to reveal the outer (concave) and inner (convex) layers. The concave cell wall layer of EDTA-sensitive cells grown in Mg(2+)-sufficient medium contained spherical units resting on an underlying smooth support layer. Upon EDTA treatment, approximately one-half of these spherical units were extracted. Cells grown in Mg(2+)-deficient medium were resistant to EDTA. The concave cell wall layer of EDTA-resistant cells had increased numbers of highly compacted spherical units, giving this layer a disorganized appearance. The highly compacted appearance of this layer was unaltered by EDTA treatment. Thus, growth in Mg(2+)-deficient medium resulted in cells which were resistant to EDTA and which possessed an ultrastructurally altered outer layer of the outer cell wall membrane. Cell envelopes from EDTA-resistant cells were found to possess 18% less phosphorus, 16.4% more total carbohydrate, and 13.3% more 2-keto-3-deoxyoctonate than cell envelopes from EDTA-sensitive cells. There were also qualitative, but not quantitative, differences in the protein content of cell envelopes from EDTA-resistant and EDTA-sensitive cells.