[Study on the relationship between copper, lysyl oxidase and premature rupture of membranes]

To determine the relationships between maternal serum copper, amniotic copper, lysyl oxidase (LOX) and collagen III in pregnant women with premature rupture of membranes (PROM) and without PROM.

One hundred women with PROM were enrolled in this study, and divided into 37-42 weeks, 34-36(+6) weeks and 28-33(+6) weeks according to gestational age. One hundred non-PROM pregnancies matching the same gestational ages were recruited as control group. Copper of maternal serum and amnion in two groups were compared by FAAS method. Amniotic LOX was analyzed by fluorometry. Amniotic collagen III was detected by immunohistochemical method and computer image analysis system (absorbance, A). Linear correlation analysis was used to explore the relationships between maternal serum copper, amniotic copper, LOX and collagen III.

(1) For 37-42 weeks pregnant women, serum copper was correlated positively with amniotic copper in two groups, r = 0.82 (P < 0.001), but for other parameters, the serum and amniotic levels had no correlations. (2) For 34-36(+6) and 28 - 33(+6) weeks pregnant women, there were positive correlations between serum copper, amniotic copper, LOX and collagen III in two groups (P < 0.01). (3) For 37-42 weeks pregnant women, serum copper and amniotic copper had no difference between two groups (P > 0.05), but amniotic LOX and collagen III decreased significantly compared with controls, being [(0.53 +/- 0.10) microg/g vs (0.75 +/- 0.10) microg/g, P < 0.01], (0.36 +/- 0.01 vs 0.37 +/- 0.01, P < 0.05) respectively. (4) For 34 - 36(+6) weeks pregnant women, serum copper, amniotic copper, LOX and collagen III reduced obviously between two groups (P < 0.01), being respectively [(115.23 +/- 9.56) mg/L vs (139.03 +/- 10.59) mg/L], [(0.21 +/- 0.04) microg/mg vs (0.29 +/- 0.04) microg/mg], [(0.54 +/- 0.10) microg/g vs (0.70 +/- 0.13) microg/g], and (0.36 +/- 0.01 vs 0.37 +/- 0.01). (5) For 28-33(+6) weeks pregnant women, serum copper, amniotic copper, LOX and collagen III also reduced obviously between two groups (P < 0.01), [(120.31 +/- 8.04) microg/L vs (136.40 +/- 8.21) microg/L], [(0.21 +/- 0.04) microg/mg vs (0.26 +/- 0.03) microg/mg], [(0.62 +/- 0.09) microg/g vs (0.72 +/- 0.09) microg/g], and (0.35 +/- 0.01 vs 0.38 +/- 0.01).

For term pregnant women, the decreases of amniotic LOX and collagen III in PROM group are not affected by serum copper, perhaps by excessive degeneration of amnion; for non-term pregnant women, the decreases of serum copper, amniotic copper, LOX and collagen III are correlated directly with PROM.