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PubMed1997

[Territorial distribution of neural tube defects in Poland].

Neural tube defects (ntd) remain unresolved therapeutic problems, even for contemporary health services. Prophylactic measures are the best methods for limitation of the problem. In many countries, the number of children born with ntd has been reduced significantly, even in 4-5 folds. Authors found that the situation in Poland remains stable since last 20 years. Epidemiological evaluation of the ntd morbidity in Poland is very difficult. There is no National Register of Inherited Defects. Authors observed and analysed mortality and hospitalisation due to ntd in Poland, in early ninetees, and compared these data with information originated from Regional (Wielkopolska) Inherited Defects Register. It was found that ntd mortality and hospitalisation in Wielkopolska was similar to average in Poland. It has been estimated that the rate of children born with ntd in Poland, in 1995 was 2.68 per 1000 live and stillbriths (in 1972-1974 was 2.04). Especially high rates of ntd's have been found in north-eastern part of Country. Incidence of ntd's was higher in rural, than in urban population of the Country.

Adult↗
PubMed1994

Vitamins, folic acid and the cause and prevention of neural tube defects.

Primary prevention of neural tube defects has been demonstrated in humans by maternal therapy with multivitamins and folic acid or folic acid alone. It has also been shown in several animal models of neural tube defects. One of these, the curly tail mouse, has been used extensively to study which agents will prevent neural tube defects in embryos when administered to the mother in early pregnancy. Prevention is achieved with retinoic acid, inositol and the DNA inhibitors hydroxyurea, mitomycin C, 5-fluorouracil and cytosine arabinoside. In no case were neural tube defects prevented in every embryo. A possible preventive effect was seen with riboflavin, vitamin C and vitamin D2. Despite the use of a variety of dose levels, no prevention was achieved with folic acid, folinic acid, Pregnavite Forte F tablets, pyridoxine or vitamin B12, or triamcinolone and cycloheximide (inhibitors of mRNA and protein synthesis, respectively), zinc, homocysteine, methionine and thymidine. Various studies have investigated whether there is a biochemical lesion in folate metabolism in women who have had children with neural tube defects. While there is no difference in their dietary intake of folate compared with control patients, the correlation between their dietary folate and the level of folate in both serum and red blood cells is distorted. Also they are less efficient at raising their folate levels after a folate load. The effects are minor but may hint at a lesion which, if identified, could act as a marker for 'at risk' women.

Animals↗
PubMed2004

Serum zinc, selenium, copper, and lead levels in women with second-trimester induced abortion resulting from neural tube defects: a preliminary study.

Neural tube defects are important causes of infant mortality and childhood morbidity. We investigated the relationship between zinc, selenium, copper, and lead concentrations and neural-tube-defect occurrence in women with a second-trimester termination due to fetal-neural-tube defects (NTDs) in this case-control study. Fourteen pregnant women whose pregnancies were terminated as a result of second-trimester ultrasonographic diagnosis of neural tube defects were recruited as cases. The control group (n = 14) consisted of women who were selected among age-, gravidity-, and socio-economic-state (SES)-matched women who had a normal triple-screen and targeted ultrasound during the second trimester with documented normal fetal outcome. Zinc and copper determinations were made using flame atomic absorption spectrophotometer (AAS). Graphite furnace AAS was used for Pb, and Se levels were measured with hydride generation AAS. Cases had significantly low serum zinc and selenium levels (62.48+/-15.9 vs 102.6+/-23.7 and 55.16+/-11.3 vs 77.4+/-5.5, respectively, p<0.001). Serum Cu and whole-blood Pb levels were significantly high when compared to controls. There was a negative correlation between serum zinc and selenium levels, and serum copper levels (r=-425 and -0.443, p<0.05). Our results are consistent with some previous reports. The etiology of NTDs cannot be explained with one strict etiologic mechanism. On the contrary, an interaction among environmental, genetic, and nutritional factors such as trace elements and vitamins would explain these anomalies. If folic acid supplementation is given, additional Zn supplementation should be considered for the further decrease in the recurrence and occurrence of NTDs.

Abortion, Induced↗
PubMed1990

The pattern of neural tube defects created by secondary reopening of the neural tube.

The usual location of human neural tube defects at the rostral or caudal end of the primary neural tube suggests they are caused by failure of closure of the neural tube. In this study, neural tube defects were created by surgical reopening of the neural tube of 3-day-old duck embryos in one of three sites: the forebrain, cervicothoracic region, or thoracolumbar region. It was determined that of the 31 survivors with forebrain incisions, 39% had exencephaly; of the 42 survivors with thoracolumbar incisions, 31% had myeloschisis; but of the 37 with a cervicothoracic incision, only 14% had exposed spinal cord. This indicates that a rostral-caudal distribution of neural tube defects can be seen in a model created by secondary reopening of the neural tube.

Anencephaly↗
PubMed1995

Multiple sites of anterior neural tube closure in humans: evidence from anterior neural tube defects (anencephaly).

OBJECTIVE: Anterior neural tube closure in humans is thought to occur via a continuous process, culminating in the closure of the anterior neuropore. Recent studies have demonstrated that, in some species, the process is discontinuous, with four separate sites of closure initiation. In this study, we tested the hypothesis that humans, like mice and other experimental animals, have multiple sites of anterior neural tube closure. METHODS: Twenty human fetuses and neonates with open anterior neural tube defects were identified. The rostral and caudal boundaries of each defect was localized on a model cranium upon which was superimposed the four sites of anterior closure characterized in the mouse. RESULTS: Of the 20 cases, 7 (35%) defects involved the frontal region, 7 (35%) were limited to the parietal region, 4 (20%) to the occipital region, and 2 (10%) involved both the parietal and occipital regions. These defects clustered into discrete regions, corresponding to sites of closure in the mouse model. The location of the defects fell into two categories; those occurring at the junction of two closures, and those occurring within a single closure. CONCLUSION: The results of this study support the hypothesis that humans, like other species, have multiple sites of anterior neural tube closure. Furthermore, the data provide evidence for two mechanisms leading to anterior neural tube defects: one resulting from the failure of a closure to occur, and the second from the failure of two closures to meet. The findings provide insight into the variations observed in the location, recurrence risk, and etiologies of anterior neural tube defects in the human population.

Anencephaly↗
PubMed1996

Periconceptional folate intake and neural tube defects.

Approximately 50% of neural tube defects may be folate-preventable and perhaps even more in other countries where prevalence is high. The Public Health Service has issued the recommendation that all women of childbearing age in the United States who are capable of becoming pregnant should consume 400 micrograms of folic acid/day for the purpose of reducing this risk. Ways in which a reproductive age woman could achieve this goal include: 1) fortifying a food sample with folic acid, 2) consuming supplements containing at least 400 mcg of folic acid, or 3) increasing nutrient intake by eating foods rich in folate. Advantages of consuming foods high in folate content are that it is a natural behavior and consistent with other dietary recommendations. However, this method is dependent upon a proper diet, and equivalencies of conjugated (dietary form) vs. unconjugated (in supplements) folate are unknown. The benefit of a supplementation policy is that the appropriate group can be targeted as pregnancies are planned, whereas primary limitations to taking a supplement would be compliance and most cases in need would not be reached. The advantage of fortification is that it is likely to reach everyone before conception, while the major disadvantage is that nontargeted populations will also receive more folic acid. Adequate consumption of folic acid should begin before and continue during at least the first 4 weeks after conception when the fetal neural tube is being formed. Standard methods of screening for neural tube defects should continue during pregnancy. The risk of a recurrent neural tube defect is 2-3%, and a higher periconception daily intake of folic acid (4 mg per day) is recommended.

Adolescent↗
PubMed1982

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 U1(-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 U1(-1), S.E.M. = 10. U1(-1), versus 1.0 U1(-1), S.E.M. = 0.2 U1(-1). The range of values (6.1-393 U1(-1)) was clearly separated from the normal values, range 0.0-5.5 U1(-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 acetylcholinesterase 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.

Acetylcholinesterase↗
PubMed1998

The prevention of neural tube defects.

The prevention of neural tube defects is a complex problem. The genetic associations may ultimately allow the prepregnancy identification of women at high risk of a neural tube defect. Education of both the public and healthcare providers has been shown to increase awareness, but the majority of women do not take folic acid before and in the early part of pregnancy. Food fortification will be effective in increasing the folate levels of the population and will have a benefit even at low doses of fortification.

Female↗
PubMedDate not supplied

A cost-benefit analysis of a population screening programme for neural tube defects.

Population screening for neural tube defects is possible by measuring maternal serum alphafetoprotein levels with appropriate follow-up as required. British Columbia has approximately 39 000 births annually and the incidence of neural tube defects is 1.55 per 1000 births (0.94 per 1000 livebirths). Results from a cost-benefit analysis suggest that the outlined screening programme would be cost-beneficial for British Columbia. Other important factors essential to consider before instituting a population screening programme are discussed.

British Columbia↗
PubMed2001

Abnormal folate metabolism and genetic polymorphism of the folate pathway in a child with Down syndrome and neural tube defect.

The association of neural tube defects (NTDs) with Down syndrome (trisomy 21) and altered folate metabolism in both mother and affected offspring provide a unique opportunity for insight into the etiologic role of folate deficiency in these congenital anomalies. We describe here the case of a male child with trisomy 21, cervical meningomyelocele, agenesis of corpus callosum, hydrocephaly, cerebellar herniation into the foramen magnum, and shallow posterior cranial fossa. Molecular analysis of the methylenetetrahydrofolate (MTHFR) gene revealed homozygosity for the mutant 677C-->T polymorphism in both the mother and child. The plasma homocysteine of the mother was highly elevated at 25.0 micromol/L and was associated with a low methionine level of 22.1 micromol/L. Her S-adenosylhomocysteine (SAH) level was three times that of reference normal women, resulting in a markedly reduced ratio of S-adenosylmethionine (SAM) to SAH and significant DNA hypomethylation in lymphocytes. The child had low plasma levels of both homocysteine and methionine and a reduced SAM/SAH ratio that was also associated with lymphocyte DNA hypomethylation. In addition, the child had a five-fold increase in cystathionine level relative to normal children, consistent with over-expression of the cystathionine beta synthase gene present on chromosome 21. We suggest that altered folate status plus homozygous mutation in the MTHFR gene in the mother could promote chromosomal instability and meiotic non-disjunction resulting in trisomy 21. Altered folate status and homozygous TT mutation in the MTHFR gene in both mother and child would be expected to increase the risk of neural tube defects. The presence of both trisomy 21 and postclosure NTD in the same child supports the need for an extended periconceptional period of maternal folate supplementation to achieve greater preventive effects for both NTD and trisomy 21.

Amino Acids, Sulfur↗
PubMedDate not supplied

[Folic acid in the prevention of neural tube defects].

INTRODUCTION: The term neural tube defects (NTD) stands for anencephaly, iniencephaly, cephalocoele and spina-bifida. The cause of these anomalies is failure of brain spinal cord to properly develop, together with their protective shield of skull and spine, around the 4th gestational week. The prevalence of NTD in continental Europe is 11.2 10,000 live births. THE LEVEL OF FOLATES IN SERUM AND NTD: The level of folates in serum can influence the risk of a child affected with NTD. Studies on women with previous pregnancies with NTD showed that supplementary intake of folic acid, with or without other vitamins, preconceptual period throughout the first trimester has a preventive effect on its recurrence. Inadequate intake of folic acid is also connected with preterm delivery, intrauterine growth retardation and placental abruption and infarction. FOLATES IN NUTRITION: It is not folic acid, but folates, from the vitamin B group, that can naturally be found in food. There are several groups of folates that differ in the quantity by which they can be absorbed from food. Folates are temperature and storage sensitive and cooking can cause a significant fall of their concentration in food. FOLIC ACID SUPPLEMENTATION: The mean daily intake of folates by food is 0.218 mg whereas a reference nutritive intake for a woman of reproductive age is 0.2 mg per day. The currently recommended daily dose for prevention of first NTD occurrence is 0.4 mg, so it is clear that a certain amount of folic acid has to be supplemented preconceptionally and during the first trimester. It can be done in two ways, by telling all women to take it before conceiving, or to fortify food with sufficiently high doses of folic acid in order to achieve adequate serum levels. Neither of the ways is ideal, for not all women would take the supplement, and by aggressively fortifying the food, we create a potential hazard to those that do not need it and may have some problems with the excess of it. The best solution would be a widespread campaign about the need for folic acid and the risks of NTD. CONCLUSION: Recommendations of The Expert Advisory Group on Folic Acid in prevention of neural tube defects has several aspects (1) reducing the risk of the first NTD occurrence by preconceptional vitamin supplementation of folic acid in the dose of 0.4 mg day, which would go on until the end of the 12th week (2) reducing the risk of NTD recurrence in offspring of men and women with spina-bifida or with obstetric history affected with NTD by preconceptional vitamin supplementation of folic acid in the dose of 4 mg daily during the first 12 weeks and (3) organizing educational programmes for medical staff as well as the whole population in order to popularize vitamin supplementation.

Female↗
PubMed1998

[Prevention using folic acid--a good method for reduction of neural tube defects in Poland].

Incidence of neural tube defects in Poland in the 90's was 2.68 in 1000 births. The value of incidence has not been changed within last twenty years. Mortality caused by neural tube defects in Poland is much higher than in many other European countries and the United States. High rates of incidence of neural tube defects in Poland is probably caused by low utilisation of methods of secondary prevention in a group of low-risk pregnant women. Since methods of primary prevention of neural-tube defects are available; primary prevention with folic acid, should be immediately implemented in Poland.

Adult↗
PubMed1992

Neural tube defects--prenatal diagnosis and management.

Neural tube defects rank second to congenital heart disease as a major cause of congenital malformation. Recent developments in ultrasound have improved prenatal diagnosis. Due to anomaly scans at 18 weeks gestation and the availability of a genetic clinic, prenatal diagnosis of neural tube defects at the Royal Maternity Hospital was 91.2% during 1987-1989. However, only 50% of parents accept termination of pregnancy and it is questionable if prenatal diagnosis is of benefit to those who wish to continue with the pregnancy. Parents may accept the situation better at birth, having had time to come to terms with it, helped with support from the obstetrician, clinical geneticist, paediatrician, genetic nurse and social worker. For some affected fetuses who have better muscle function and leg movement at term it appears from the literature that the outcome may be improved by caesarean section delivery. In Ireland fetuses with neural tube defects will continue to be delivered, as termination is unacceptable to many, but despite this there may be a positive benefit from prenatal diagnosis of neural tube defects. Prospective randomised controlled trials are needed to confirm benefit from delivery by caesarean section for fetuses with a good prognosis. As a result of prenatal diagnosis of a neural tube lesion the fetus should enjoy benefit in terms of physical morbidity, and the parents should benefit in terms of psychological morbidity.

Abortion, Induced↗
PubMed1987

Prenatal diagnosis policy without routine amniocentesis in pregnancies with a positive family history for neural tube defects.

The recurrence risk for neural tube defects in pregnancies of women with a family history of neural tube defects greatly exceeds the general population risk. In these high risk pregnancies, we used a prenatal diagnostic method differing from that usually employed, relying mainly on the results of maternal serum alpha-fetoprotein (MSAFP) and ultrasound examination, without routine amniocentesis. During the 6 years reviewed in this study, this method was applied in 539 pregnancies. Of a total of 20 neural tube defects, 19 were detected using this combination of MSAFP, ultrasound, and selective amniocentesis, and the authors estimate that about 8-10 spontaneous abortions were avoided because only 28 amniocenteses were carried out instead of 539. The risk of recurrence was found to be lower than that experienced earlier.

Amniocentesis↗
PubMed1985

Maternal serum alpha-fetoprotein screening for neural tube defects. Report of a combined study in Germany and short overview on screening in populations with low birth prevalence of neural tube defects.

The basis of maternal serum alpha-fetoprotein (AFP)-screening for neural tube defects is discussed. A report is given of a large scale screening study in the Federal Republic of Germany combining the experiences in Giessen and Hannover on over 50,000 pregnant women, about evenly distributed among both centers. Published and known forthcoming data from other low incidence populations, particularly of European countries, are reviewed briefly. The conclusion is reached that general screening could effectively be instituted and in the final result should also be cost-beneficial.

Amniotic Fluid↗
PubMed1998

Prevention of neural tube defects: vitamins, enzymes and genes.

Neural tube defects can be prevented by folic acid, although the mechanism of this action is unclear. Studies of a series of folate-related enzymes have so far failed to pin-point the nature of the metabolic defect in the neurulation-stage embryo that is corrected by folic acid. Approximately 30% of neural tube defects appear resistant to folic acid and recent work in a mouse genetic model system suggests that administration of myo-inositol may be a complementary therapeutic option. The large number of mouse genes known to cause neural tube defects provide a starting point for identifying the genetic basis of the human defects.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1999

Folic acid supplementation of pregnant mice suppresses heat-induced neural tube defects in the offspring.

Neural tube defects (NTD) are a group of malformations that result from the failure of the neural tube to close early in embryonic development and among the most common congenital malformations in humans. It has been reported that a substantial proportion of NTD in humans can be prevented by folic acid (FA) supplementation prior to conception and during the first months of pregnancy, and myo-inositol (MI) was shown to reduce the incidence of NTD in curly tail mice which are not prevented by FA. Brief maternal hyperthermia (HT) early in pregnancy has been implicated in NTD both in humans and laboratory animals, and anterior NTD including exencephaly and anencephaly are induced frequently when pregnant mice are exposed to HT. We examined the effect of FA or MI supplementation of pregnant mice on the occurrence of heat-induced NTD in the offspring. When pregnant mice were treated with FA (3 mg/kg) daily from gestational day (GD) 0.5 through GD 9.5 and heated at GD 8.5, the prevalence of NTD in the fetuses (26.6%) was significantly lower than the corresponding figure in the HT alone group (38.6%; P < 0.05). However we failed to detect the preventive effect of MI (500 mg/kg). The results of this study suggest that prenatal FA supplementation decreases HT-induced NTD in mice and sufficient FA intake during early pregnancy may be recommended to avoid the birth of malformed children.

Analysis of Variance↗