A study on the metabolic pathway of pregnancy specific beta 1-glycoprotein (SP1). Report 1: Change of pregnancy specific beta 1-glycoprotein (SP1) in urine during normal gestation (author's transl)

Abstract

For the purpose of studying the metabolic course of pregnancy, specific β1 -glycoprotein (SP1), the urinary protein in normal pregnancy was investigated and compared with SP1 in the serum.1) Urine was concentrated 20-fold by ammonium sulphate precipitation, and SP1 was detected using immunological methods with commercially available anti-SP1 serum. By the gel immunodiffusion methods, one precipitation line was formed with the serum of pregnant women, but two lines were formed with their urine. By the single radial immunodiffusion method (SRID), a single-ring was detected in the serum, but a double-ring was detected in the urine.When gel filtration of the concentrated urine was performed with a Sephadex G-150 gel column, there were two peaks for SP1 concentration. Each fraction of the two peaks showed a single-ring by SRID, but a double-ring was found at the intermediate fractions of the two. Furthermore, the mixture of each fraction of the two peaks formed a similar double-ring. SP1 in the fraction of the first peak (tentatively SP1 -A) was found to be the same as SP1 in the serum, and SP1 in the second peak (tentatively SP1-B) was specific to urine from pregnant women by the agar gel immunodiffusion method. This observation indicates that there are two kinds of SP1 in the urine, each having a different molecular weight. In the urine, SP1 -A forms an inner clear ring and SP1 -B forms an outer indistinct ring by SRID.2) The concentrations of SP1 -A and SP1 -B in 10-fold concentrated urine were measured by SRID in 255 normal pregnant women at various gestational ages. These proteins gradually increased with gestation and reached the highest concentrations at the 10th month. The precipitation ring was found in 203 urine samples out of 255 cases (80%), and the double-ring was detected in 135 out of 255 cases (53%). The positive ratio of the double-ring increased until the 9th month of gestation but slightly decreased in the 10th month. The reason for this remains to be solved.3) The expected daily excretion of SP1 was calculated from creatinin-corrected SP1 concentration. The excretion of SP1 -A increased gradually during the whole gestational period, while the excretion of SP1 -B increased slowly until the 5th month and then rapidly during the remaining gestational months. Both SP1 -A and SP1 -B were excreted the most in the 10th month.4) The correlation coefficient was calculated between SP1 concentrations in the serum and urine. It was found that SP1 -B (r =0.63, p<0.001) correlated with SP1 in the serum more significantly than SP1 -A (r= 0.38, p<0.05).