Lethal fetal and early neonatal presentation of adenylosuccinate lyase deficiency: observation of 6 patients in 4 families

OBJECTIVE

To characterize a new lethal fetal and early postnatal variant of adenylosuccinate lyase (ADSL) deficiency.

STUDY DESIGN

This was a retrospective analysis of 6 patients with very early presentation of ADSL deficiency.

RESULTS

Most of the 6 patients had impaired intrauterine growth, microcephaly, fetal hypokinesia, and a lack of fetal heart rate variability. Postnatally, they shared severe muscular hypotonia necessitating mechanical ventilation, intractable seizures, and early death. All 6 patients had biochemical evidence of severe (type 1) disease and low residual ADSL activities. All were compound heterozygous for mutations that, based on expression studies, have a pronounced effect on ADSL activity and/or stability.

CONCLUSIONS

ADSL deficiency may present with prenatal growth restriction, fetal and neonatal hypokinesia, and rapidly fatal neonatal encephalopathy. This clinical presentation is associated with genotypes resulting in very low residual enzyme activity.

[Enzymatic diagnostics in obstetrics and gynecology. Part I]

The object of this paper is to highlight the importance of enzymatic diagnostics in obstetrics and gynecology. Enzymatic diagnostics through the assessment of oxytocinase allows to monitor the pregnancy and predict the delivery. Oxytocinase and its isoenzymes reflect the present state of the mother, the fetus and the placenta. The constant increase of oxytocinase in maternal blood up to the time of delivery and its appropriate level indicates the proper development of pregnancy. Low lewel and above all decrease in level instead of the normal constant increase precedes by several weeks clinical symptoms of abortions and preterm deliveries. Maternal blood levels of cystine-amino-peptidases (CAP1 and CAP2) show high correlation with the fetal and placental mass as well as fetal maturity. The levels of oxytocinase allow to objectivize the duration of pregnancy and to reduce induced and operative deliveries.

Histone H3-K9 methyltransferase ESET is essential for early development

Methylation of histone H3 at lysine 9 (H3-K9) mediates heterochromatin formation by forming a binding site for HP1 and also participates in silencing gene expression at euchromatic sites. ESET, G9a, SUV39-h1, SUV39-h2, and Eu-HMTase are histone methyltransferases that catalyze H3-K9 methylation in mammalian cells. Previous studies demonstrate that the SUV39-h proteins are preferentially targeted to the pericentric heterochromatin, and mice lacking both Suv39-h genes show cytogenetic abnormalities and an increased incidence of lymphoma. G9a methylates H3-K9 in euchromatin, and G9a null embryos die at 8.5 days postcoitum (dpc). G9a null embryo stem (ES) cells show altered DNA methylation in the Prader-Willi imprinted region and ectopic expression of the Mage genes. So far, an Eu-HMTase mouse knockout has not been reported. ESET catalyzes methylation of H3-K9 and localizes mainly in euchromatin. To investigate the in vivo function of Eset, we have generated an allele that lacks the entire pre- and post-SET domains and that expresses lacZ under the endogenous regulation of the Eset gene. We found that zygotic Eset expression begins at the blastocyst stage and is ubiquitous during postimplantation mouse development, while the maternal Eset transcripts are present in oocytes and persist throughout preimplantation development. The homozygous mutations of Eset resulted in peri-implantation lethality between 3.5 and 5.5 dpc. Blastocysts null for Eset were recovered but in less than Mendelian ratios. Upon culturing, 18 of 24 Eset(-/-) blastocysts showed defective growth of the inner cell mass and, in contrast to the approximately 65% recovery of wild-type and Eset(+/-) ES cells, no Eset(-/-) ES cell lines were obtained. Global H3-K9 trimethylation and DNA methylation at IAP repeats in Eset(-/-) blastocyst outgrowths were not dramatically altered. Together, these results suggest that Eset is required for peri-implantation development and the survival of ES cells.

Liver disintegration in the mouse embryo caused by deficiency in the RNA-editing enzyme ADAR1

ADAR1 (adenosine deaminase acting on RNA-1) is widely expressed in mammals, but its biological role is unknown. We show here by gene targeting that ADAR1 selectively edits in vivo two of five closely spaced adenosines in the serotonin 5-hydroxytryptamine subtype 2C receptor pre-mRNA of nervous tissue; and hence, site-selective adenosine-to-inosine editing is indeed a function of ADAR1. Remarkably, homozygosity for two different null alleles of ADAR1 caused a consistent embryonic phenotype appearing early at embryonic day 11 and leading to death between embryonic days 11.5 and 12.5. This phenotype manifests a rapidly disintegrating liver structure, along with severe defects in definitive hematopoiesis, encompassing both erythroid and myeloid/granuloid progenitors as well as spleen colony-forming activity from the aorta-gonad-mesonephros region and fetal liver. Probably as a consequence of these developmental impairments, ADAR1-deficient embryonic stem cells failed to contribute to liver, bone marrow, spleen, thymus, and blood in adult chimeric mice. Thus, ADAR1 subserves critical steps in developing non-nervous tissue, which are likely to include transcript editing.

Disruption of the regulatory beta subunit of protein kinase CK2 in mice leads to a cell-autonomous defect and early embryonic lethality

Protein kinase CK2 is a ubiquitous protein kinase implicated in proliferation and cell survival. Its regulatory beta subunit, CK2beta, which is encoded by a single gene in mammals, has been suspected of regulating other protein kinases. In this work, we show that knockout of the CK2beta gene in mice leads to postimplantation lethality. Mutant embryos were reduced in size at embryonic day 6.5 (E6.5). They did not exhibit signs of apoptosis but did show reduced cell proliferation. Mutant embryos were resorbed at E7.5. In vitro, CK2beta(-/-) morula development stopped after the blastocyst stage. Attempts to generate homozygous embryonic stem (ES) cells failed. By using a conditional knockout approach, we show that lack of CK2beta is deleterious for mouse ES cells and primary embryonic fibroblasts. This is in contrast to what occurs with yeast cells, which can survive without functional CK2beta. Thus, our study demonstrates that in mammals, CK2beta is essential for viability at the cellular level, possibly because it acquired new functions during evolution.

Maternally transmitted severe glucose 6-phosphate dehydrogenase deficiency is an embryonic lethal

Mouse chimeras from embryonic stem cells in which the X-linked glucose 6-phosphate dehydrogenase (G6PD) gene had been targeted were crossed with normal females. First-generation (F(1)) G6PD(+/-) heterozygotes born from this cross were essentially normal; analysis of their tissues demonstrated strong selection for cells with the targeted G6PD allele on the inactive X chromosome. When these F(1) G6PD(+/-) females were bred to normal males, only normal G6PD mice were born, because: (i) hemizygous G6PD(-) male embryos died by E10.5 and their development was arrested from E7.5, the time of onset of blood circulation; (ii) heterozygous G6PD(+/-) females showed abnormalities from E8.5, and died by E11.5; and (iii) severe pathological changes were present in the placenta of both G6PD(-) and G6PD(+/-) embryos. Thus, G6PD is not indispensable for early embryo development; however, severe G6PD deficiency in the extraembryonic tissues (consequent on selective inactivation of the normal paternal G6PD allele) impairs the development of the placenta and causes death of the embryo. Most importantly, G6PD is indispensable for survival when the embryo is exposed to oxygen through its blood supply.

Oxytocinase as the most important marker of fetal development

Enzymes as biochemical markers come within the entire scope of the live mother-fetus system. The most important are the enzymes which regulate physiological processes, of which oxytocinase (a type of aminopeptidase) has a much wider scope of action than its name suggests, as it regulates also the level of aminopeptide hypothalamic hormones. Thus, it determines neurological, endocrinological and immunological regulation of entire steroidogenesis. Under the influence of gestational enlargement of the uterine cavity, the mothers hypothalamus produces an increasing amount of hormones, which in turn induces an increasing oxytocinase synthesis in the placenta in order to prevent the hormone in the blood reaching the level which could bring about uterine contractions. Also, the growing fetus additionally induces the production of oxytocinase by releasing its own hormones. All this occurs in combined action of the mother, fetus, placenta and even fetal membranes in one space-time process called pregnancy. When in the late pregnancy the enzyme remains at constant level or decreases without appearance of uterus contractions, labour induction is necessary due to fetus life hazard of as much as several percent. Reduction in enzyme level and even its insufficient growth in the second trimester of pregnancy, occur several weeks before preterm birth or death of the fetus. On the other hand, in the event of treatment of diseases accompanying the pregnancy,normalization of oxytocynasaemia shows the effectiveness of treatment. With the dominating profile of the steady increase of oxytocinase (>90% of cases), the target values are higher than in the case of irregular growth. Their close values are a result of the hormonal treatment of threatened pregnancies with ACTH depot. In the cases of the primary hypothalamic insufficiency, this treatment reduces the rate of fetal deaths, which would stand at several dozen percent. It is a classical example of biological pregnancy monitoring since the risk of fetal death can be predicted several weeks earlier when assessment of chemical compounds or physical changes still gives accurate results within physiological limits.

Neonatal and fetal methylenetetrahydrofolate reductase genetic polymorphisms: an examination of C677T and A1298C mutations

Methylenetetrahydrofolate reductase (MTHFR) mutations are commonly associated with hyperhomocysteinemia, and, through their defects in homocysteine metabolism, they have been implicated as risk factors for neural tube defects and unexplained, recurrent embryo losses in early pregnancy. Folate sufficiency is thought to play an integral role in the phenotypic expression of MTHFR mutations. Samples of neonatal cord blood (n=119) and fetal tissue (n=161) were analyzed for MTHFR C677T and A1298C mutations to determine whether certain MTHFR genotype combinations were associated with decreased in utero viability. Mutation analysis revealed that all possible MTHFR genotype combinations were represented in the fetal group, demonstrating that 677T and 1298C alleles could occur in both cis and trans configurations. Combined 677CT/1298CC and 677TT/1298CC genotypes, which contain three and four mutant alleles, respectively, were not observed in the neonatal group (P=.0402). This suggests decreased viability among fetuses carrying these mutations and a possible selection disadvantage among fetuses with increased numbers of mutant MTHFR alleles. This is the first report that describes the existence of human MTHFR 677CT/1298CC and 677TT/1298CC genotypes and demonstrates their potential role in compromised fetal viability.

Embryonic lethality, liver degeneration, and impaired NF-kappa B activation in IKK-beta-deficient mice

IkappaB kinase-alpha and -beta (IKK-alpha and IKK-beta), the catalytic subunits of the IKK complex, phosphorylate IkappaB proteins on specific serine residues, thus targeting IkappaB for degradation and activating the transcription factor NF-kappaB. To elucidate the in vivo function of IKK-beta, we generated IKK-beta-deficient mice. The homozygous mouse embryo dies at approximately 14.5 days of gestation due to liver degeneration and apoptosis. IKK-beta-deficient embryonic fibroblasts have both reduced basal NF-kappaB activity and impaired cytokine-induced NF-kappaB activation. Similarly, basal and cytokine-inducible kinase activities of the IKK complex are greatly reduced in IKK-beta-deficient cells. These results indicate that IKK-beta is crucial for liver development and regulation of NF-kappaB activity and that IKK-alpha can only partially compensate for the loss of IKK-beta.

3-Hydroxy-3-methylglutaryl-CoA lyase (HL): gene targeting causes prenatal lethality in HL-deficient mice

3-Hydroxy-3-methylglutaryl-CoA lyase (HL, EC 4.1.3.4) catalyses the last step of ketogenesis from leucine and fatty acids. HL deficiency in humans is one of the many inborn errors of CoA ester metabolism. By gene targeting, we created a strain of HL-deficient mice. Heterozygous HL-deficient mice are clinically normal and fibroblasts from homozygous HL-deficient embryos grow normally despite absence of HL activity. In contrast, homozygous HL-deficient embryos die at approximately 11.5 days post-coitum. Histologically, HL-deficient embryos show marked vacuolization, particularly in liver. Ultrastructural studies of hepatocytes obtained before death from HL-deficient embryos reveal abnormal dilated mitochondria. HL-deficient mice are the first mammalian example of a disease primarily affecting CoA ester metabolism with abnormal prenatal development.

The nature of antioxidant defense mechanisms: a lesson from transgenic studies

Reactive oxygen species (ROS) have been implicated in the pathogenesis of many clinical disorders such as adult respiratory distress syndrome, ischemia-reperfusion injury, atherosclerosis, neurodegenerative diseases, and cancer. Genetically engineered animal models have been used as a tool for understanding the function of various antioxidant enzymes in cellular defense mechanisms against various types of oxidant tissue injury. Transgenic mice overexpressing three isoforms of superoxide dismutase, catalase, and the cellular glutathione peroxidase (GSHPx-1) in various tissues show an increased tolerance to ischemia-reperfusion heart and brain injury, hyperoxia, cold-induced brain edema, adriamycin, and paraquat toxicity. These results have provided for the first time direct evidence demonstrating the importance of each of these antioxidant enzymes in protecting the animals against the injury resulting from these insults, as well as the effect of an enhanced level of antioxidant in ameliorating the oxidant tissue injury. To evaluate further the nature of these enzymes in antioxidant defense, gene knockout mice deficient in copper-zinc superoxide dismutase (CuZnSOD) and GSHPx-1 have also been generated in our laboratory. These mice developed normally and showed no marked pathologic changes under normal physiologic conditions. In addition, a deficiency in these genes had no effects on animal survival under hyperoxida. However, these knockout mice exhibited a pronounced susceptibility to paraquat toxicity and myocardial ischemia-reperfusion injury. Furthermore, female mice lacking CuZnSOD also displayed a marked increase in postimplantation embryonic lethality. These animals should provide a useful model for uncovering the identity of ROS that participate in the pathogenesis of various clinical disorders and for defining the role of each antioxidant enzyme in cellular defense against oxidant-mediated tissue injury.

Disruption of murine alpha-enolase by a retroviral gene trap results in early embryonic lethality

Gene trapping with the retroviral ROSA beta geo vector was used to generate lines of mice carrying disrupted genes. Both cDNA and genomic flanks have been cloned from a number of these lines. One mutation has been shown to disrupt the alpha-enolase gene by insertion of the splice-trap vector into the first intron. In adult mice, lacZ expression was detected only in testes. Embryonic expression was detected from 10.5-day postcoitum embryos and was seen as a diffuse staining pattern over much of the embryo, consistent with the housekeeping gene function of alpha-enolase. This mutation results in an early recessive embryonic lethality. Mice heterozygous for the mutation have no obvious phenotype. Mutations of this gene in humans are reported to be associated with rare autosomal-dominant, non-spherocytic haemolytic anaemia. This phenotype is not reproduced in mice heterozygous for this mutation.

Mutations in the 11 beta-hydroxysteroid dehydrogenase type II enzyme associated with hypertension and possibly stillbirth

The 11 beta-hydroxysteroid dehydrogenase type II enzyme (11 beta HSD2) converts cortisol into cortisone, thus preventing occupation of the non-selective mineralocorticoid receptor by glucocorticoids in the kidney. Placental 11 beta HSD2 is also thought to protect the fetus from the high maternal circulating levels of glucocorticoids. Mutations generating inactive enzymes have been described in the HSD11B2 gene in the congenital syndrome of apparent mineralocorticoid excess (AME)--a low renin form of hypertension. Recently, a mutation has been identified in a family with AME and in which there is a high incidence of stillbirths. In this study we have expressed the R374X mutation and show that the mutant is devoid of enzyme activity in intact mammalian cells expressing a significant level of the truncated protein. While this observation elucidates the cause of AME in this family the degree to which R374X also contributes to the higher incidence of failed pregnancies remains to be determined.

Fetal death in mice lacking 5alpha-reductase type 1 caused by estrogen excess

Female mice deficient in steroid 5alpha-reductase type 1 have a decreased litter size. The average litter in homozygous deficient females is 2.7 pups vs. 8.0 pups in wild type controls. Oogenesis, fertilization, implantation, and placental morphology appear normal in the mutant animals. Fetal loss occurs between gestation days 10.75 and 11.0 commensurate with a midpregnancy surge in placental androgen production and an induction of 5alpha-reductase type 1 expression in the decidua of wild type mice. Plasma levels of androstenedione and testosterone are 2- to 3-fold higher on gestation day 9, and estradiol levels are chronically elevated by 2- to 3-fold throughout early and midgestation in the knockout mice. Administration of an estrogen receptor antagonist or inhibitors of aromatase reverse the high rate of fetal death in the mutant mice, and estradiol treatment of wild type pregnant mice causes fetal wastage. The results suggest that in the deficient mice, a failure to 5alpha-reduce androgens leads to their conversion to estrogens, which in turn causes fetal death in midgestation. These findings indicate that the 5alpha-reduction of androgens in female animals plays a crucial role in guarding against estrogen toxicity during pregnancy.

Mice lacking N-acetylglucosaminyltransferase I activity die at mid-gestation, revealing an essential role for complex or hybrid N-linked carbohydrates

Eukaryotic cells require N-linked carbohydrates for survival. However, the biosynthetic intermediate Man5GlcNAc2Asn, in place of mature N-linked structures, allows glycoprotein synthesis and somatic cell growth to proceed normally. To determine whether the same would be true in a complex biological situation, the gene Mgat-1 was disrupted by homologous recombination in embryonic stem cells and transmitted to the germ line. The Mgat-1 gene encodes N-acetylglucosaminyltransferase I [GlcNAc-TI; alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase; UDP-N-acetyl-D-glucosamine:glycoprotein (N-acetyl-D-glucosamine to alpha-D-mannosyl-1,3-(R1)-beta-D-mannosyl-R2) beta-1,2-N-acetyl-D-glucosaminyltransferase, EC 2.4.1.101], the transferase that initiates synthesis of hybrid and complex N-linked carbohydrates from Man5GlcNAc2Asn. Mice lacking GlcNAc-TI activity did not survive to term. Biochemical and morphological analyses of embryos from 8.5 to 13.5 days of gestation showed that Mgat-1-/-embryos are developmentally retarded, most noticeably in neural tissue, and die between 9.5 and 10.5 days of development.

Hereditary lactate dehydrogenase A-subunit deficiency as cause of early postimplantation death of homozygotes in Mus musculus

Two ethylnitrosourea-induced heterozygous mouse mutants with approximately 58 and 50% of wild-type lactate dehydrogenase (LDH) activity and a gamma-ray-induced heterozygous mutant with 50% of wild-type LDH activity in blood, liver and spleen (expressing predominantly the Ldh-1 gene) were recovered in mutagenicity experiments following spermatogonial treatment. Physiological and genetic studies revealed no indications for differences in fertility as well as hematological or other physiological traits between heterozygotes of each mutant line and wild types. This suggests that neither the mutations in the heterozygous state per se nor the resulting approximate 42 to 50% LDH deficiency affect metabolism and fitness. Physicochemical and immunological studies clearly demonstrated that the two mutations with 50% deficiency in heterozygotes result from null alleles of the Ldh-1 structural locus, generating neither enzyme activity nor immunological cross-reacting material. In contrast, the heterozygous mutant with approximately 58% of normal blood LDH activity was shown to be due to a Ldh-1 allele creating protein subunits, which in random assortment with wild-type subunits in vivo exhibit a reduced specific activity and further alterations of kinetic and physicochemical characteristics. All the mutations in the homozygous state were found to be lethal at an early postimplantation stage of embryonic development, probably due to a block of glycolysis with the corresponding loss of the main source of metabolic energy during this ontogenetic stage. The distinct physiological consequences of the total absence of a functioning LDH-A subunit in mice and humans are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Ratio of immunochemically determined amniotic fluid acetylcholinesterase to butyrylcholinesterase in the differential diagnosis of fetal abnormalities

A total of 111 amniotic fluid samples, clear or blood stained, with elevated levels of alpha-fetoprotein and acetylcholinesterase was analysed by immunoassays specific for acetylcholinesterase and butyrylcholinesterase and the acetylcholinesterase/butyrylcholinesterase-ratios determined. Samples from 40 pregnancies associated with anencephaly, 47 pregnancies associated with open spina bifida or encephalocele and six pregnancies with fetal intrauterine death or miscarriage all had ratios of greater than 0.14. All 11 pregnancies with fetal ventral wall defects had ratios less than 0.14 as had four pregnancies with normal outcome and elevated levels of alpha-fetoprotein and acetylcholinesterase. Three fetuses with both open spina bifida and ventral wall defects were associated with ratios above 0.14. These results suggest that immunochemical determination of acetylcholinesterase and butyrylcholinesterase can be used to distinguish pregnancies complicated by anencephaly, open spina bifida, encephalocele and miscarriage from those with ventral wall defects and samples with false positive elevated levels of alpha-fetoprotein and acetylcholinesterase. The procedure is accurate and simple to carry out and well suited to routine use in a clinical chemistry laboratory.

Increased amniotic acetylcholinesterase activity with a fetus papyraceus and aplasia cutis congenita

A case of an infant with aplasia cutis congenita, a fetus papyraceus, abnormal maternal serum alpha-fetoprotein (MSAFP), elevated amniotic alpha-fetoprotein, and positive amniotic acetylcholinesterase activity represents an uncommon abnormality. Such a case came to our attention as a result of MSAFP screening. The delivery of a neurologically intact infant in the presence of amniotic acetylcholinesterase activity is described.

Glycolytic enzymes of human fetal and neonatal intraocular fluids

The levels of the glycolytic enzymes, phosphohexose isomerase, aldolase and LDH and its isozymes, were ascertained in the aqueous of human stillbirths and premature neonate dead (19-24 weeks gestation) and compared with those of older neonates (28-41 weeks) of low survival due mainly to respiratory failure. The fetal aqueous displayed a much greater LDH-P level (mean mU/ml +/- SEM: 45,600 +/- 2550; 72 eyes) in contrast to the near-term infant value (2420 +/- 615; 27 eyes) and 8-20 times higher aldolase and phosphohexose isomerase levels. LDH-P of the fetal vitreous was much lower (5820 +/- 860 mU/ml; 25 eyes) and for lens employed as a filtered homogenate in saline (1:20), amounted to 52.2 +/- 4.2 mU/mg lens (24 eyes). The distribution of LDH isozymes in the fetal vitreous and lens homogenate and the near-term neonate aqueous as determined by polyacrylamide disc electrophoresis, was similar to that of the fetal aqueous, LDH-1 and LDH-5 being least and LDH-3 and LDH-4, the highest. A few small but significant differences were apparent as compared to the fetal aqueous isozymes and included decrements in vitreous LDH-4, lens LDH-3 and neonatal aqueous LDH-3 and increases in vitreous LDH-2 and near-term aqueous LDH-4. The current findings may have application to retinoblastoma for which higher aqueous LDH levels have been reported and employed as a diagnostic adjunct. However, the fetal aqueous LDH values far exceed those encountered in this embryonal-type tumour.

Maternal serum diamine oxidase in fetal death and low-birth-weight infants

Serum diamine oxidase was measured at different gestational ages in 681 pregnancies resulting in live births and 102 pregnancies resulting in fetal deaths. Statistical analysis revealed that gestational age-adjusted diamine oxidase levels in the fetal-death group were significantly lower (P less than 0.001) than those in the live-birth group. Moreover, the relative risk associated with a low diamine oxidase level, compared with a normal level, increased from 3.7 at 8 weeks to 16.6 at 12 weeks. Pregnancies resulting in low-birth-weight infants exhibited normal serum diamine oxidase levels. The association between low diamine oxidase and subsequent fetal death is discussed in view of the hypothesis that polyamines and polyamine-degrading enzymes interact to protect the fetoplacental unit from immune rejection.

[Oxytocinase: levels in normal and pathological pregnancies]

The author has determined the levels of plasma oxytocinase in a series of normal and pathological pregnancies. It appears from studying these levels that it is useful to measure the oxytocinase particularly in cases where there is failure of intra-uterine growth.

Enzymes in amniotic fluid

The determination of enzyme levels in cell-free amniotic fluid has proven useful in assessing fetal maturity and fetal well being, and is being utilized for the prenatal diagnosis of genetic disorders. The activities of amylase, alpha-galactosidase, phosphatidic acid phosphohydrolase, lysozyme and heat-stable alkaline phosphatase in amniotic fluid increase with gestational age and have an established relationship to fetal maturity. The ratio of amniotic fluid diamine oxidase activity to maternal serum activity (amniotic DAO/serum DAO) may be used as an indicator of the degree of rhesus isoimmunization after 28 weeks gestation. Creatine phosphokinase in amniotic fluid is elevated in cases of in utero fetal death and is of diagnostic significance. The prenatal diagnosis of Tay-Sachs disease, Sandhoff's disease, fucosidosis, GM1-gangliosidosis and I-cell disease have been made from the analysis of appropriate enzymes in cell-free amniotic fluid.

Maternal serum hyaluronidase activity in pregnancy

An unselected series of 291 pregnant women was followed during pregnancy. Maternal serum was assayed for both hyaluraonidase activity and HPL. Urine was assayed for 24 h oestrogen output. A retrospective examination of the results showed that hyaluronidase activity did not provide as good an indication of fetoplacental well-being as did either HPL or pregnancy oestrogen. There were differences, however, in the mean levels obtained in complicated pregnancy, compared to the levels in normal pregnancy. Fetal death was associated with increased hyaluronidase activity whereas fetoplacental dysfunction was associated with lower levels of hyaluronidase activity.

Prenatal diagnosis and fetal pathology of Tay-Sachs disease

In 6 cases of high risk pregnancies for Tay-Sachs disease, prenatal diagnosis was successfully carried out by examining hexosaminidase A activity in the supernatant of amniotic fluid and the uncultured and cultured amniotic fluid cells. In 5 out of 6 cases, the activity of hexosaminidase A was found to be within normal or heterozygous levels. They continued their pregnancies and were delivered of healthy children. In the remaining 1 case, the activity was undetected. Her pregnancy was terminated at the 23rd week of gestation. There was no activity of hexosamindase A in the brain and liver from the aborted fetus. A moderate increase in GM2 ganglioside was found in the brain. Electron-microscopic findings revealed membranous cytoplasmic bodies in the spinal ganglion cells as well as in the nerve cells of the retina. These biochemical and histological findings of Tay-Sachs fetus suggest that the disease proceeds early in fetal period. It was found that the cultured amniotic fluid cells was the most reliable material for the prenatal diagnosis of Tay-Sachs disease, because the values of hexoxaminidase A in the cultured cells were well in accord with those in serum from the consequently bord children. Hexosaminidase pattern in the supernatant of amniotic fluid on DEAE-cellulose columnchromatogram showed a distinct difference between homozygote, heterozygote and normal. This procedure also may be useful for prenatal diagnosis of Tay-Sachs disease.

Termination of pregnancy after accelerated lactation in the rat. IV. Relationship to 20alpha-hydroxysteroid dehydrogenase activity and plasma progesterone concentration

The activity of 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) was assayed in the ovaries of rats after accelerated lactation to determine its relationship to the decrease in progesteron secretion that occurs. When rats were sjbjected to accelerated lactation on Day 9 of pregnancy, activity of the enzyme was only slightly increased by Day 10, but had risen to twice the control level by Day 11, and three times the control level by Day 12. Administration of LH or progesterone prevented the increase in enzyme activity. Progesterone concentration had decreased considerably before the time at which any significant increase in 20alpha-HSD activity was detected. These findings are discussed in relation to the role of 20alpha-HSF in regulating progesterone levels in the rat.

Deoxycytidylate deaminase in pregnancy

Deoxycytidylate (DCMP) deaminase was assayed at various times during and after normal and abnormal pregnancies. The level in amniotic fluid was assessed at induction and at caesarean section, and cord blood levels were estimated after normal delivery and at caesarean section. A rise occurred during labour and after hysterectomy and caesarean section--returning to normal after 2-3, and 12 days respectively. Levels above 4.8 X 10-minus 4 ml-minus 1 were found in cases of preeclamptic toxaemia and early intrauterine death and in twin pregnancies over 36 weeks' gestation. It is suggested that because of its low incidence of false-negative and false-positive results this test is far superior to other enzyme tests in pregnancy, and a further trial is in progress to assess its role.