Enzyme Activity In Amniotic Fluid Research Articles

Prenatal Detection by Real-Time Quantitative PCR and Characterization of a New CFTR Deletion, 3600+15kbdel5.3kb (or CFTRdele19)

Cystic fibrosis (CF; MIM No. 219700), the most common autosomal recessive disease in Caucasians (1), is caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR; MIM No. 602421) (2). The disease may be revealed by fetal bowel hyperechogenicity during routine ultrasonography in the second trimester of pregnancy, even when there is no family history of CF. However, fetal bowel hyperechogenicity is not specific for CF: when found at this stage of pregnancy, it corresponds to CF in 2–20% of cases (1)(3)(4)(5). Diagnostic investigations are based on screening for CF-causing mutations, fetal karyotyping, and screening for infections. Normal intestinal enzyme activities in amniotic fluid before 18 weeks of gestation reasonably rules out CF (6). However, most women are referred after this time, and it is necessary to screen for CF mutations in the parents and, if possible, fetus. To date, almost 900 mutations have been described throughout the CFTR gene, but very few deletions have been identified (7). Indeed, large deletions are not routinely screened for, given their rarity and the lack of suitable diagnostic tools. Conventional PCR-based methods usually detect deletions only when they are present in the homozygous state. As a result, the frequency of CFTR deletions is underestimated. Two relatively frequent large deletions have recently been described: 3120+1kbdel8.6kb was found in 13% of CF chromosomes in Israeli-Arab patients (8), and CFTRdele2,3 accounts for 1–6.4% of CF chromosomes in Slavic populations (9). A couple was referred to our laboratory for fetal hyperechogenic bowel diagnosed during a routine ultrasound scan at 20 weeks of gestation. The couple, who were first cousins of Turkish extraction, had no family history of CF. Diagnostic investigations were requested after genetic counseling, with the couple’s informed consent. The fetal karyotype (amniotic cells) was normal, as …

Microvillar enzyme activity in amniotic fluid, extraembryonic coelomic fluid and maternal serum in the first trimester of pregnancy

The activities of two microvillar enzymes, γ-glutamyl transpeptidase and total alkaline phosphatase, have been measured in samples of amniotic fluid and extraembryonic coelomic fluid obtained by high-resolution transvaginal ultrasound-guided amniocentesis from 40 women between 7 and 12 weeks of gestation. There was a highly significant difference between γ-glutamyl transpeptidase activity in amniotic fluid (median level 31 U/l; range 2–409 U/l) and extraembryonic coelomic fluid (median level 2 U/l; range < 2–16 U/l) ( P < 0.001; Mann-Whitney U-test). Alkaline phosphatase activity was not detected in 84% of amniotic fluid samples and 97% of extraembryonic coelomic fluid samples. No difference was found between total alkaline phosphatase activity in these fluids ( P = 0.14; Mann-Whitney U-test). Enzyme activities in amniotic fluid increased with gestational age. A significant linear correlation was found between amniotic fluid γ-glutamyl transpeptidase activity and stage of gestation ( r = 0.86; P < 0.001) and total alkaline phosphatase activity in amniotic fluid and stage of gestation ( r = 0.66; P < 0.001).

Prenatal diagnostic options in cystic fibrosis

There are currently two diagnostic options in cystic fibrosis. These involve assays for cetain microvillar enzyme activities in amniotic fluid and recombinant deoxyribonucleic acid studies of markers linked to the cystic fibrosis gene on chromosome 7. The former are reduced in cystic fibrosis homozygotes; the latter make it possible to determine the particular pattern of chromosome 7 markers predictive of a cystic fibrosis homozygote in a specific family. However, neither test is appropriate for, applicable to, or informative in all families. The problems and potential of each approach are discussed.

Enzyme activities in amniotic fluid and maternal blood in sheep, before and after induced foetal death and abortion.

Abstract Tissue enzymes, LDH, AST, ALT, AP, TACP and CK, were measured in amniotic fluid collected from ten chronically-catheterized (intra-amniotic) ewes from 90 to 105 days of gestation until abortion occurred or, in five ewes, the lambs were removed by hysterotomy. Bacterial contamination occurred either during or after surgery in six of the ewes; in eight ewes a test inoculum of Staphylococcus aureus was infused into the amniotic sac. All six enzymes increased in activity in the amniotic fluid just before foetal death or abortion. However, with the exception of one ewe in which amniotic fluid enzyme activity reached very high values, there were no parallel changes in the maternal plasma.

Enzyme activities in amniotic fluid and maternal blood in cattle before and after induced foetal death and abortion

Tissue enzymes, LDH, AST, ALT, AP, TACP and CK, were measured in amniotic fluid obtained from slaughtered pregnant cows, and also in maternal plasma and amniotic fluid collected from seven chronically catheterized cows between 180 and 200 days of gestation. Following bacterial contamination, during or after surgery, or inoculation with a culture of Staphylococcus aureus, the measured enzyme activities in the amniotic fluid increased just before the induced foetal death and abortion. Maternal plasma enzymes did not show comparable changes but remained fairly constant at the time of foetal death and abortion.

Prenatal diagnosis of hunter syndrome

Sixteen pregnancies at risk for Hunter syndrome have been monitored by amniocentesis. Iduronate 2-sulphate sulphatase levels were measured in amniotic fluid, cultured amniotic fluid cells and cord blood. Thirteen of the pregnancies resulted in normal livebirths, two are continuing and one affected pregnancy was terminated. Reduced enzyme levels were observed in either amniotic fluid, cells or cord blood for four female fetuses. Such fetuses are likely to be carriers expressing reduced enzyme levels. The affected male fetus had reduced enzyme activity in amniotic fluid; insufficient cells were cultured for enzyme estimation, however no enzyme activity was detected in fetal liver after termination. Eight cord blood enzyme estimations have been performed, five confirming normal male infants.

Acetylcholinesterase in neural tube defects: A model using chick embryo amniotic fluid

Acetylcholinesterase was measured in amniotic fluid from normal chick embryos and embryos with neural tube defects. Neural tube defects were induced in the chick embryos by three procedures, removal of albumen, mechanical disruption of the closed neural tube or injection of tetanus toxin. The concentration of acetylcholinesterase in amniotic fluid from untreated normal embryos changed throughout the period examined (5–14 days incubation) but was stable at 0.5 Ul −1 over the time period 6–11 days. Amniotic fluid taken from treated embryos with neural tube defects at 8 days always contained a higher concentration of acetylcholinesterase than fluid from sham operated but otherwise normal embryos, mean 40.9 Ul −1,S.E.M. = 10.1 Ul −1, versus 1.0 Ul −1,S.E.M. = 0.2 Ul −1. The range of values (6.1–393 Ul −1) was clearly separated from the normal values, range 0.0–5.5 Ul −1. In 13 cases with developmental abnormalities other than neural tube defects, the concentration of acetylcholinesterase was elevated in only one. Two different forms of acetylcholinesterase, as shown by gel electrophoresis, were present in fluid form both normal and defective embryos. These forms were also present in blood plasma, cerebrospinal fluid and in the high speed supernatant from brain extracts, the latter tissue contained an additional form of greater electrophoretic mobility. After irreversible inhibition, enzyme activity in amniotic fluid recovered slowly; only half the control value was reached by 140 h compared with complete recovery in the tissues of the embryo within 19 h. Histochemical staining for acetycholinesterase showed that the spinal cord in the region of the lesion contained high concentrations of the enzyme. The possible sources of acetylcholinesterase in amniotic fluid are discussed. This chicken model of neural tube defects provides support for the use of acetylcholinesterase tests in the detection of neural tube defects clinically, and provides a model for experimentation with this system.

γ-Glutamyl transpeptidase of human amniotic fluid

γ-Glutamyl transpeptidase (GGTP) activity in normal amniotic fluids and corresponding maternal sera obtained at various gestational periods was measured. The ontogenic pattern of enzyme activity in amniotic fluid is very similar to alpha fetoprotein (AFP). However, the levels of these two proteins behaved differently in corresponding maternal sera. Also, in amniotic fluids obtained from pregnancies with neural tube defects (NTD), only AFP concentration was abnormally high whereas GGTP activity was normal.

Disaccharidase and Lysosomal Enzyme Activities in Amniotic Fluid, Intestinal Mucosa and Meconium

Brush border membrane bound disaccharidases (sucrase and maltase) and lysosomal enzyme (alpha-glucosidase, beta-D-fucosidase and N-acetyl-beta-glucosaminidase) activities awere studied in amniotic fluid (AF). The above enzymes except N-acetyl-beta-glucosaminidase showed a decrease in activity with gestational age beginning at about the 19th week. The activities of sucrase and maltase correlate with the morphological maturation of fetal intestinal mucosa. The distribution of disaccharidases and lysosomal alpha-glucosidase in AF and intestinal mucosa showed different patterns suggesting that these enzymes originate in diverse fetal tissues.

Prenatal diagnosis of fucosidosis

Pregnancy from a family at risk for fucosidosis was monitored. The fetus was diagnosed as having a carrier state of the disease. α-L-fucosidase activity, however, was found to be absent in white blood cells obtained from identical twins after delivery. The diagnostic evaluation of (1) the enzyme activity in amniotic fluid and in cultivated amniotic fluid cells and (2) the presence of fucose rich compound in amniotic fluid are discussed.