Oxytocin in maternal circulation and amniotic fluid during pregnancy.

Oxytocin (OT) was measured by a specific and sensitive RIA in plasma and amniotic fluid throughout pregnancy. OT was detectable in 84.5% of 362 maternal plasma samples and showed a slow and fluctuating increase towards term with a significant sharp peak at 39 weeks of gestation.

Studies of oxytocin in the baboon during pregnancy and delivery.

Oxytocin was determined by radioimmunoassay in pregnant baboons throughout gestation, in the foetus at caesarean section, and after oxytocin infusion into the mother and foetus. Serial maternal plasma oxytocin in 6 baboons during pregnancy showed a significant correlation between the gestational age and maternal plasma oxytocin concentrations with a correlation coefficient of r = 0.3185 and P less than 0.

Variable nature of cartilage proteoglycans.

Cartilage proteoglycan aggregates are separated from collagen and other non-proteoglycan protein by preparative rate zonal sedimentation under associative conditions. Dissociative rate zonal sedimentation produces sedimented proteoglycan of lower protein content with a corresponding increase in the amount of less sedimentable protein-rich proteoglycan. An extensive number of sequential rate zonal sedimentations discloses that the proceess of disaggregation involves the separation of proteoglycans varying continuously in composition with no apparent discontinuities in distribution to indicate the presence of distinctively different macromolecules.

Distribution studies of proteoglycan aggregates by ultracentrifugation.

The tendency forcartilage proteoglycans to aggregate or disperse in ultracentrifugation at high ionic strength is influenced by cations. Guanidinum, Li+ and Ca++ promote disaggregation and Na+, K+ and Cs+ support aggregation. The process of disaggregation is fundamentally the separation of low density from high density proteoglycans, the density being an inverse function of the protein content.