Decreased high-molecular weight fibrinogen and impaired alpha-chain polymerization in full-term newborns.

Some properties of fibrinogen from 30 newborn and 30 normal adult plasmas obtained under the same conditions have been studied. The results show that the high-molecular weight fibrinogen (HMW-Fg) was decreased by nearly 25% in newborn plasma as compared to normal adult values. The kinetics of fibrin gel formation was decreased in newborn as compared with normal adult plasmas (gelation rates 2.2 +/- 1 vs. 5.6 +/- 0.5 x 10(-4) OD/s, lag time 128 +/- 25 vs. 72 +/- 3 s). The release rates of fibrinopeptide A (FPAp +/- FPA) and fibrinopeptide B (FPB) were decreased in newborn fibrinogen (FPAp + FPA 10.8 and FPB 1.2 x 10(-3) s-1) as compared to normal adult fibrinogen (FPAp + FPA 11.8 and FPB 1.7 x 10(-3) s-1). Analysis by SDS-PAGE of the reduced, highly cross-linked fibrin from the newborns showed that only 23% of the alpha-chain participates in the formation of alpha-chain polymers. The results suggest that the retarded release rate of fibrinopeptides and the decrease in the HMW fibrinogen concentration are causes of the prolonged kinetics of fibrin gel formation in newborns.