Acute phase modulation of systemic insulin-like growth factor-1 and its binding proteins after major burn injuries.
OBJECTIVE
To provide a detailed, sequential analysis of insulin-like growth factor-1 and its binding proteins in adults during the acute phase after a major burn injury.


METHODS
Descriptive, repeated measurements for quantitation and characterization of insulin-like growth factor-1 and its binding proteins in adult burn survivors.


METHODS
Burn center in a university hospital.


METHODS
A total of 17 severely burned (>15% total body-surface area burned) adult patients.


METHODS
Venous blood was collected twice a day for 10 days and centrifuged, and the sera were stored at -80 degrees C until analysis. A series of 340 serum samples were analyzed by radioimmunoassay to determine the circulating concentration of insulin-like growth factor-1 and its major binding proteins (insulin-like growth factor-binding protein), by Western ligand blotting. To better understand the changes seen in systemic insulin-like growth factor-binding protein-3 levels by Western ligand blotting, a proteolysis assay was performed.


RESULTS
Insulin-like growth factor-1 levels were reduced from day 0 and correlated with insulin-like growth factor-binding protein-1 and -2 (p <.01), but not insulin-like growth factor-binding protein-3 and -4. Insulin-like growth factor-binding protein-3 was decreased relative to normal on day 0, declined further until day 3, and began recovering by day 6, but returned to only 35% of normal by day 10. Insulin-like growth factor-binding protein-1 and -2 were increased relative to normal and remained increased throughout the 10-day period. Insulin-like growth factor-binding protein-4 concentrations, however, were similar to normal at day 1 but gradually increased over time. Burn serum incubated with recombinant human glycosylated iodine-125 insulin-like growth factor-binding protein-3 did not demonstrate any proteolysis, although proteolysis of nonglycosylated iodine-125 insulin-like growth factor-binding protein-3 reached levels of approximately 40%.


CONCLUSIONS
Insulin-like growth factor-binding protein-3 proteolysis does not seem to be the mechanism by which systemic insulin-like growth factor-1 levels are reduced in major burn survivors. In vitro proteolysis of recombinant human glycosylated and nonglycosylated iodine-125 insulin-like growth factor-binding protein-3 does not reflect the in vivo situation in major burn survivors.
Nedelec
Bernadette
B
McGill University, Montreal, Quebec, Canada.
de Oliveira
Ana
A
Garrel
Dominique R
DR
D000210:Acute-Phase Reaction / Q000097:blood*; D000293:Adolescent; D000328:Adult; D000368:Aged; D002056:Burns / Q000097:blood / Q000276:immunology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis
D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I