Neural-tube defects are associated with low concentrations of cobalamin (vitamin B12) in amniotic fluid.

While folate supplementation reduces the risk of recurrent neural-tube defects (NTD), both folate and cobalamin deficiencies may be independent risk-factors for neural-tube defects. Folate-dependence and impaired remethylation of homocysteine are implicated as mechanisms for NTD. There are few references reported for folate, cobalamin, homocysteine and methionine in the fetal compartment.

Prospective evaluation of maternal serum human chorionic gonadotropin levels in 3428 pregnancies.

As part of a multicenter prospective study, second-trimester human chorionic gonadotropin and alpha-fetoprotein concentrations were evaluated. Data included maternal age, human chorionic gonadotropin level, alpha-fetoprotein level, weight, race, and pregnancy outcome of 3428 pregnancies at between 15 and 20 weeks' gestation. The results of the study indicate that human chorionic gonadotropin levels decrease as maternal weight increases, that weight-adjusted human chorionic gonadotropin levels for Oriental and black women are higher than for white or Hispanic women, and that twin pregnancies have higher human chorionic gonadotropin levels than singleton pregnancies.

Prenatal ascertainment of triploidy by maternal serum alpha-fetoprotein screening.

We report our experience in ascertaining fetal triploidy during routine maternal serum alpha-fetoprotein (MSAFP) screening. Three cases were identified after elevated MSAFP tests. Two of the three had normal amniotic fluid alpha-fetoprotein (AFAFP).

Interaction of cyclosporin A with human lipoproteins.

The ultracentrifugal fractionation of human serum after previous incubation with cyclosporin A showed that, in healthy fasting individuals, 8% of cyclosporin A was found in the very low density lipoproteins (VLDL), 31% in the low density lipoproteins (LDL), 46% in the high density lipoproteins (HDL) and 15% in the non-lipoprotein protein fraction. In non-fasted, healthy and in non-fasted, lipaemic individuals, 7 and 6% of cyclosporin A was found in chylomicrons, 9 and 13% in VLDL, 28 and 30% in LDL, 39 and 37% in HDL, and 12 and 13% in the non-lipoprotein protein fraction, respectively. In patients receiving cyclosporin A the distribution varied from 12 to 19% in VLDL, 21 to 28% in LDL, 33 to 43% in HDL, and 13 to 20% in non-lipoprotein proteins.

A simple ultrafiltration method for determining unbound estradiol in serum.

The Amicon MPS-1 centrifugal ultrafiltration device and the YMT membrane were used to measure free estradiol in serum. Two independent assays were required. The first measured total estradiol-17 beta and the second ultrafiltrable fraction.

A simplified ultrafiltration method for determination of serum free cortisol.

We describe the suitability of the Amicon MPS-1 centrifugal ultrafiltration device and the YMB membrane for measuring free cortisol in serum. The method combines two independent assays: total cortisol and the ultrafiltrate fraction of added [3H]cortisol. The unbound fraction is determined in 0.

Manganese, calcium, and saccharide binding to concanavalin A, as studied by ultrafiltration.

The binding of the ligands Mn2+, Ca2+, and methyl alpha-D-glucopyranoside to concanavalin A, purified as described (A.J. Sophianopoulos and J.

An improved ultrafiltration method for determining free testosterone in serum.

In this method, we use the Amicon MPS-1 centrifugal ultrafiltration device and the YMB membrane in measuring free testosterone in serum. Two independent assays are combined: total testosterone and the ultrafiltrable fraction of added [3H]testosterone. The unbound fraction is determined in 0.