Maternal serum screening for Down syndrome in the first trimester: experience from Belarus.

We have carried out a large retrospective study of alpha-fetoprotein (AFP), free-beta human chorionic gonadotrophin (hCG) and pregnancy-associated plasma protein (PAPP-A) in the first trimester of pregnancy. Unlike other studies all women had routine ultrasound dating, carried out during a nuchal translucency measurement project. A total of 13,477 serum samples were tested for AFP and 11,659 for free beta-hCG. A subset of 1564 samples from unaffected pregnancies were also tested for PAPP-A on a case-control basis. All three markers were also determined in 31 samples from pregnancies with Down syndrome. Equations were derived to express results in multiples of the median using both gestational age and crown rump length and to adjust for maternal weight. Statistical modelling with Gaussian distribution parameters obtained in the study were used to predict the detection rate for a 5 per cent false-positive rate. The predicted rates were: 73.7 per cent for all three markers; 69.1 per cent for PAPP-A and free beta-hCG; 47.4 per cent for PAPP-A and AFP; 57.6 per cent for free beta-hCG and AFP. As these rates are similar to those in the second trimester, health planners may now want to consider a change in policy from second-trimester to first-trimester screening with biochemical markers.

[Comparison of spectrophotometric and fluorimetric methods of determination of galactocerebroside-beta-D-galactosidase in leukocytes]. / Sravnenie spektrofotometricheskogo i fluorimetricheskogo metodov opredeleniia aktivnosti galaktotserebrozid-beta-D-galaktozidazy v leikotsitakh.

A procedure was developed for estimation of galactocerebroside beta-D-galactosidase activity in leukocytes using a new fluorogenic compound 6-hexadecanoylamino-4-methylum-belliferyl-beta-D-galactop yra noside (HMGal) as a substrate. Some patterns of the fluorometric procedure were compared with corresponding parameters of the spectrophotometric method in which a chromogenic substrate HNGal was used. Sensitivity of the fluorometric procedure with HMGal as a substrate was increased 100-fold as compared with the spectrophotometric method. At the same time, the fluorometric procedure enabled to reduce considerably the incubation period and the cell protein content per an assay. High sensitivity and reproducibility of the procedure with HMGal as a substrate allowed to carry out biochemical diagnosis of Krabbe disease in leukocytes.

[Lysosomal hydrolase activity of the plasma and leukocytes of homo- and heterozygotes with various types of I-cell disease]. / Aktivnosti lizosomnykh gidrolaz plazmy i leikotsitov u gomo- i geterozigot s razlichnymi variantami I-kletochnoi bolezni.

One patient with I-cell disease and three patients with pseudo Hurler polydystrophy as well as their relatives were examined. Activity of acid hydrolases was distinctly elevated in blood plasma of all the patients studied, while in leukocyte extracts it was within the normal limits. The ratio of hexosaminidase A was distinctly decreased in blood plasma of the patient with I-cell disease and of her mother. "Low activity" variant of blood plasma alpha-fucosidase was detected in one patient with pseudo Hurler polydystrophy and in his father. The ratio of bound sialic acids in supernatant and in individual leukocyte fractions was about I in all the patients examined as compared with 0.3-0.5 value in healthy persons. The data obtained suggest an excessive storage of soluble sialyl-containing derivatives in leukocytes of the patients with different variants of I-cell disease.

[Transplacental effect of urethane on DNA synthesis in mouse embryonal lung tissue during organotypical cultivation]. / Transplatsentarnoe vliianie uretana na sintez DNK v émbrional'noi legochnoi tkani myshei v usloviiakh organotipicheskogo kul'tivirovaniia.

Kinetics of DNA synthesis was estimated by autoradiography in the organ cultures of murine embryonic lung tissue. Strain A mice were taken for this experiment (intact and exposed to transplacental action of urethane--30 mg/g to a pregnant mouse, subcutaneously, once). The explants were examined 1,7, 15 and 21 days after the cultivation. Transplacental urethane inhibited DNA synthesis the first 24 hours. The label index became approximately 3 times less. The next two days it was restored and then stimulated. The maximal label index was noted in the experimental explants on the 7th cultivation day, i.e. on the 8th-10th day after the transplacental action of urethane on the lung tissue in utero. By the 15th cultivation day the label index dropped but was higher than in the intact explants; by the 21st day DNA synthesis in the intact cultures ceased completely, whereas in the experimental animals--it continued.