Placental transfer of stobadine in rabbits

Stobadine, a pyridoindole antioxidant, was investigated for its placental transfer and distribution in New Zealand white rabbits on the 27th day of gestation. The concentrations of stobadine were determined in maternal and foetal organs (plasma, brain, heart) at 30, 60, 120, and 360 minutes after oral administration of the drug in a dose of 5 mg/kg. The results obtained proved that after oral stobadine intake by rabbits at the stage of advanced pregnancy both maternal and foetal organs were under a certain drug level which could act protectively against oxidative stress--frequently occurring during late organogenesis, foetal stages and delivery, as well as during early postnatal development.

Intrauterine growth retardation associated with maternal uniparental disomy for chromosome 6 unmasked by congenital adrenal hyperplasia

We report the first case of maternal uniparental disomy for chromosome 6 (UPD6mat) ascertained through congenital adrenal hyperplasia (CAH), which arose because of reduction to homozygosity of an autosomal recessive mutation. This case suggests that UPD6mat is associated with intrauterine growth retardation (IUGR). A case of paternal UPD (involving only the short arm of chromosome 6) ascertained as CAH has previously been reported, but was not stated to have IUGR. Our patient was born with IUGR followed by extraordinarily good catch-up growth. She had a history of a marked lag in motor development. She presented at 2.65 y of age with pubarche of 3 mo duration, clitoral enlargement, and an advanced bone age. Simple virilizing CAH was diagnosed by elevations of plasma 17-hydroxyprogesterone and testosterone. Mutation analysis showed that the CAH was due to homozygosity for the 1172N exon 4 mutation. When parental DNA was examined, the mother was found to be heterozygous for the uncommon exon 4 mutation, while the father had no detectable mutations. DNA microsatellite analysis was subsequently performed on the patient and parents using polymorphic markers spanning the entire chromosome 6. Seven markers were informative for inheritance of a single maternal allele and absence of paternal alleles in the proband. Analysis of microsatellite markers from other chromosomes confirmed biparental inheritance at these loci. This combination of findings is diagnostic of UPD6mat. The only other reported case of UPD6mat was discovered serendipitously when genotyped for renal transplantation; this patient had a history of IUGR. Since both cases of UPD6mat had IUGR, the phenotype appears to include IUGR as well as the potential to unmask an autosomal recessive trait.

Fetal-to-maternal transfer of 3,3',5-triiodothyronine sulfate and its metabolite in sheep

Earlier studies have shown that sulfoconjugation is a major pathway of thyroid hormone metabolism in fetal mammals. To assess the placental transfer of sulfoconjugates in the pregnant sheep model, we measured 3,3',5-triiodothyronine (T(3)) sulfate (T(3)S), 3, 3'-diiodothyronine sulfate (T(2)S), and T(3) concentrations in fetal serum and in maternal serum and urine after T(3)S infusion to the fetus (n = 5) or the ewe (n = 6). Maternal infusion of T(3)S did not increase fetal serum T(2)S, T(3)S, or T(3) concentrations. In contrast, fetal infusion of T(3)S produced significant increases in maternal serum T(2)S and T(3)S but not T(3) concentrations. Fetal T(3)S infusion also increased maternal urine excretion of T(3)S. However, the 4-h cumulative maternal urinary excretion of T(2)S and T(3)S after fetal T(3)S infusion was less than the excretion observed after fetal infusion of equimolar amounts of T(3) in our previous study. It is concluded that fetal serum T(2)S and T(3)S can be transferred to maternal compartments. However, compared with T(3), these sulfoconjugates may be less readily transferred.

SHORT COMMUNICATION maternal thyroid dysfunction and c- fos and c- jun expression in rat placenta

Maternal thyroid dysfunction is associated with perturbed fetal brain development and neurological deficits in adulthood in rat and human. To investigate whether these effects occur secondary to placental dysfunction, c- fos and c- jun expression in placenta from normal (euthyroid) and moderately hypothyroid rat dams were investigated by Northern hybridization analysis. In normal placenta, c- fos expression increased by 74 per cent between 16 and 21 days of gestation (dg) whereas c- jun expression declined by 46 per cent. Moderate maternal hypothyroidism depressed placental c- fos expression by 32 per cent at 19 dg, but elevated c- fos and c- jun expression by 139 and 86 per cent, respectively, at 21 dg. Maternal hypothyroidism may therefore induce c- fos/c- jun -related placental dysfunction, but only relatively late in gestation when fetal thyroid function is already established.

The neonatal implications of a high placental ratio in small-for-gestational age infants

An increased placental ratio has been associated with small-for-gestational age (SGA) infants. A retrospective study on 252 singleton SGA infants without major anomalies born within a 1-year period was performed to determine the relationship between placental ratio and maternal/infant characteristics, and perinatal complications. The cases were categorized into three groups according to the placental ratio (<1 sd below the mean, within 1 sd of the mean, >1 sd above the mean) based on our previous data. There were more infants with a high ratio (32.9 per cent) than with a low ratio (15.5 per cent). While there was no difference in the maternal characteristics or antenatal complications, there was a significant trend in decreasing birthweight and an increasing placental weight in relation to an increasing placental ratio. The infants with a high ratio had increased incidence of meconium stained liquor, hypocalcaemia, hypomagnesaemia and phototherapy, a trend that was consistent even after exclusion of the preterm infants. Our data indicated that a high placental ratio in SGA infants was due to both increased placental size and decreased birthweight, and this was associated with increased neonatal morbidity.

Maternal infection, fetal inflammatory response, and brain damage in very low birth weight infants. Developmental Epidemiology Network Investigators

Echolucent images (EL) of cerebral white matter, seen on cranial ultrasonographic scans of very low birth weight newborns, predict motor and cognitive limitations. We tested the hypothesis that markers of maternal and feto-placental infection were associated with risks of both early (diagnosed at a median age of 7 d) and late (median age = 21 d) EL in a multi-center cohort of 1078 infants <1500 x g. Maternal infection was indicated by fever, leukocytosis, and receipt of antibiotic; fetoplacental inflammation was indicated by the presence of fetal vasculitis (i.e. of the placental chorionic plate or the umbilical cord). The effect of membrane inflammation was also assessed. All analyses were performed separately in infants born within 1 h of membrane rupture (n = 537), or after a longer interval (n = 541), to determine whether infection markers have different effects in infants who are unlikely to have experienced ascending amniotic sac infection as a consequence of membrane rupture. Placental membrane inflammation by itself was not associated with risk of EL at any time. The risks of both early and late EL were substantially increased in infants with fetal vasculitis, but the association with early EL was found only in infants born > or =1 after membrane rupture and who had membrane inflammation (adjusted OR not calculable), whereas the association of fetal vasculitis with late EL was seen only in infants born <1 h after membrane rupture (OR = 10.8; p = 0.05). Maternal receipt of antibiotic in the 24 h just before delivery was associated with late EL only if delivery occurred <1 h after membrane rupture (OR = 6.9; p = 0.01). Indicators of maternal infection and of a fetal inflammatory response are strongly and independently associated with EL, particularly late EL.

Accuracy of the haemoglobin alkaline denaturation test for detecting maternal blood contamination of fetal blood samples for prenatal karyotyping

The haemoglobin alkaline denaturation test was routinely performed in 183 fetal blood samples obtained by cordocentesis for prenatal karyotyping by adding 0.1 ml of the blood into a glass test tube containing 5 ml of water and 0.3 ml of 10 per cent KOH as the alkali reagent. The mixture was agitated gently and read at 2 minutes, at which time it was interpreted as a pure fetal blood sample or contaminated with maternal blood according to the change in colour. In order to determine the accuracy of this test to detect maternal blood contamination, the results were compared with the number of fetal and maternal cells detected by standard cytogenetic techniques in those blood samples obtained from male fetuses (n=97). Among these samples, the haemoglobin alkaline denaturation test gave an adult haemoglobin reaction in two cases (2.1 per cent); both samples showed different degrees of maternal 46,XX cells in the metaphases examined (29 of 30 cells in one case and 2 of 31 cells in the other). Conversely, of the 95 samples which gave a fetal haemoglobin reaction, the cytogenetic analysis did not reveal any maternal cells in the metaphases analysed (median 30 cells, range 20-65). We concluded that the haemoglobin alkaline denaturation test is an accurate method for excluding clinically significant maternal blood contamination of fetal blood samples obtained for prenatal karyotyping. This simple, inexpensive technique provides immediate information and, therefore, can be safely incorporated as a bedside test for analysis during fetal blood sampling procedures.

Transplacental exposure to antipsychotic drugs during pregnancy and megacystis in the fetus

Urinary retention is an adverse effect of antipsychotic drugs that has not been previously reported in the fetus. We have diagnosed megacystis in a fetus possibly caused by transplacental exposure to the antipsychotic drugs being administered to the mother. Two weeks after the mother stopped taking the drugs, the size of the enlarged fetal urinary bladder returned to normal. Sonographic examination of the neonate revealed an anatomically normal urinary tract, with a normal bladder capacity and urination.

The proform of eosinophil major basic protein: a new maternal serum marker for Down syndrome

The proform of eosinophil major basic protein (proMBP), the most abundant protein in the eosinophil specific granule, is synthesized by the placenta and secreted into the maternal circulation, where it is found complex-bound to pregnancy-associated plasma protein-A (PAPP-A) and other proteins. We examined the potential of proMBP as a maternal serum marker for fetal Down syndrome (DS) by determining its maternal serum concentration (MSpMBP) in 25 Down syndrome (DS) pregnancies and 152 control pregnancies in the first trimester, and in 105 DS pregnancies and 156 control pregnancies in the second trimester. The median (95 per cent confidence interval) MSpMBP MoM in DS pregnancies (n=15) was 0.66 (0.49-0.79) in gestational weeks 5-9; 1.06 (0.71-1.97) in weeks 10-12 (n=10) and 1.62 (1.18-1.98) in weeks 14-20 (n=105). Using parameterized receiver operator characteristics analysis for proMBP as a single marker for DS, detection rates (DRs) of 22 per cent and 38 per cent, for false-positive rates (FPRs) of 5 per cent, were found in weeks 5-9 (using MSpMBP</=cut-off) and weeks 14-20 (using MSpMBP>/=cut-off), respectively. When age and MSpMBP were used as markers in combination, a DR of 36.8 per cent for an FPR of 5.5 per cent was obtained in weeks 5-9 using a risk cut-off of 1:250. In weeks 14-20 the DR was 48.4 per cent for an FPR of 5.3 per cent using the same risk cut-off. This makes proMBP a marker comparable in diagnostic efficiency to human chorionic gonadotrophin (hCG), and exceeding that of alpha-fetoprotein (AFP) and unconjugated oestriol (uE3), in the second trimester.

Immunoassay and GC-MS procedures for the analysis of drugs of abuse in meconium

The analysis of meconium specimens for metabolites of substances of abuse is a relatively accurate method for the detection of fetal exposure to drugs. Most of the methods reported in the literature before the early 1990s relied on radioimmunoassays. The purpose of this study was to develop and validate methods for meconium sample preparation for the screening and gas chromatography-mass spectrometry (GC-MS) confirmation of meconium extracts for cannabinoids, cocaine, opiates, amphetamines, and phencyclidine. EMIT and TDx immunoassays were evaluated as screening methods. The sample preparation method developed for screening included extraction and purification prior to analysis. Cutoff levels were administratively set at 20 ng/g for 11-nor-delta9-THC-9-COOH (THCCOOH) and phencyclidine and at 200 ng/g for benzoylecgonine, morphine, and amphetamines, although lower levels could be detected in meconium using the EMIT-ETS system. Ninety-five meconium specimens were subjected to the screening procedure with GC-MS confirmation of presumptive positives. In addition, 30 (40 for cocaine) meconium specimens were subjected to GC-MS analysis for all analytes regardless of the screening results to determine the false-negative rate, if any, of the immunoassay. Although there were no false negatives detected, the GC-MS confirmation rate for the immunoassay-positive specimens was generally low, ranging from 0% for amphetamines to 75% for opiates. The lowest rate of confirmed positives was found with the cannabinoids, suggesting that tetrahydrocannabinol (THC) metabolites other than free 11-nor-9-carboxy-delta9-THC may be major contributors to the immunoassay response in meconium.

Collaborative study of maternal urine beta -core human chorionic gonadotrophin screening for Down syndrome

Several studies have shown that second-trimester maternal urine beta-core human chorionic gonadotrophin (hCG) levels are raised on average in Down syndrome pregnancies. However, in all but one, testing was retrospective after extended sample storage and so we carried out a large international multicentre prospective study. 16 centres provided 6730 samples from 14-19 week pregnancies: 39 with Down syndrome, 12 with Edwards' syndrome, 42 with other aneuploidies, 52 unaffected twins and 6585 singleton unaffected pregnancies. Samples were from those having routine maternal serum screening in 6 centres and invasive prenatal diagnosis for reasons unrelated to maternal serum screening in 10 centres. Normalized levels of beta-core hCG (nmom/mmol creatinine) were expressed as multiples of the gestation-specific normal median (MoMs). The median beta-core hCG level in Down syndrome was 1.70 MoM (95 per cent confidence interval, 1.26-2.30); 14 (36 per cent) exceeded the normal 90th centile and 9 (23 per cent) the 95th centile. The median level in Edwards' syndrome was 0.23 MoM. On the basis of our results alone it is unlikely that urinary beta-core hCG will be a useful marker in Down syndrome screening practice. But the considerable variability in results between studies means that further research is needed before a reliable conclusion can be drawn.

Prenatal diagnosis on fetal cells obtained from maternal peripheral blood: report of 66 cases

The potential use of fetal cells circulating in maternal blood for a non-invasive prenatal diagnosis has been widely described. Several authors have developed different methods for the enrichment of fetal cells from maternal peripheral blood. The aim of this study was to make a practical valuation of this new prenatal diagnosis technique, using those methods described as efficient and easy to carry out in a prenatal diagnosis unit. These methods consist of the double-density gradient and the positive selection by magnetic activated cell sorting (MACS) of the fetal erythroblasts, and the posterior study of the cells applying the FISH interphasic technique. Once the technique was ready, we obtained results from the study of 66 venous blood samples from women coming for prenatal diagnosis. Using a specific staining for fetal haemoglobin, fetal cells were identified in 63 cases. Fetal sex was well determined in 56 cases, 23 females and 33 males; in 7 cases the sex determination failed. All the aneuploidies found in a previous prenatal diagnosis were confirmed.

Maternal urine hyperglycosylated hCG in pregnancies with Down syndrome

Stored maternal urine samples were used to determine the distribution of hyperglycosylated human chorionic gonadotrophin (H-hCG) levels in pregnancies with Down syndrome. A total of 349 samples from singleton pregnancies, including 45 with Down syndrome, were tested at 10-19 weeks' gestation. Urinary concentration was allowed for by expressing H-hCG in ng per mmol creatinine. The median level in Down syndrome was 3.63 multiples of the gestation-specific median in unaffected pregnancies (p<0.0001, Wilcoxon rank-sum test, two-tail). However, creatinine levels were relatively low in cases and creatinine did not fully correct for concentration. When this bias was allowed for, the median level was 3.34 multiples of the normal median (MoM). The H-hCG elevation in affected pregnancies was more marked at 14 weeks' gestation or later: a median of 4.64 MoM and allowing for creatinine bias 4.46 MoM.

Olanzapine transfer by human placenta

1. The present study assessed the human transplacental transport of olanzapine, a new antipsychotic drug effective in the treatment of schizophrenia. 2. Using the normal-term placenta perfused single cotyledon system, we show that: (i) 5-14% of labelled olanzapine crosses from the maternal to foetal compartments in 4 h; (ii) transport depends significantly on binding characteristics, especially of albumin; (iii) no oxidative metabolites of olanzapine appear in the placental perfusate over 4 h; and (iv) approximately 17% of olanzapine, on average, is converted to the glucuronide, which is transferred by the placenta at a rate slightly slower than the parent drug.

Effect of glucose load on the transport kinetics of palmitic acid in the human placenta: an in vitro study

1. A paucity of data relating to free fatty acid (FFA) transport in the human placenta in non-steady state conditions prompted us to undertake the present study. 2. The transport kinetics of palmitic acid in non-steady state conditions have been investigated in vitro using human perfused placental lobules. The effects of varying glucose concentrations on maternal-foetal transport of the FFA were also investigated to mimic the hyperglycaemic states of human diabetic pregnancies. 3. National Cancer Tissue Culture medium diluted with Earle's buffered salt solution was used as the perfusate. [14C]-Palmitic acid, along with tritiated water as a reference, was injected as a bolus into the maternal arterial perfusate and perfusate samples were collected from the venous outflow for a period of 5 min. 4. The transport fraction (TF) of palmitic acid, expressed as percentage of the injected bolus, averaged 3.45 +/- 0.15% in five perfusions, representing 9.2 +/- 1.3% of the corresponding reference marker TF. Kinetic parameters, as well as TF indices of palmitic acid expressed in relation to the reference substance, did not differ significantly between perfusions with a physiological glucose load and those with hyperglycaemic concentrations of glucose of 27.8 and 55.6 mmol/L. 5. The present study shows that hyperglycaemia per se does not significantly alter palmitic acid transport kinetics in vitro in the human perfused placental lobule.

Role of insulin-like growth factor binding protein 1 in human pregnancy

Insulin-like growth factors and their binding proteins are key regulators of fetal and maternal tissue growth and development during human pregnancy. Insulin-like growth factors, particularly IGF-II, are produced in abundance by the trophoblast cells of the placenta, whereas one of the insulin-like growth factor binding proteins, IGFBP-1, is the major secretory product of the maternal decidualized endometrium. This spatial (and temporal expression) of the insulin-like growth factor axis infers a sophisticated paracrine regulatory mechanism for controlling insulin-like growth factor function. This paper reviews the potential roles of IGFBP-1 in human pregnancy by examining its effects on growth, metabolism and migration at the maternal-fetal interface and how these might be influenced by autocrine-paracrine post-translational modifications.

[The influence of hypokinesia on the mother-fetus system]

In experiments with rats effects of hypokinesia on the course of pregnancy and the mother-fetus system were investigated. Immobilization in penal-type cages of female rats on days 8 through to 19 of pregnancy gave rise to significant shifts in mother's organism, i.e. retarded body mass gain, mass reductions in thymus, spleen, liver, some other organs, and adipose tissue. Rates of prenatal fatality in the experimental group were not changed; yet, fetuses were behind the control by the values of body mass, ossification ranges, development of analyzers and other parameters. Quantities of liquid, sodium, magnesium and calcium per one gram of dry tissue were equal in the experimental and control fetuses. Comparison of the data with results of the embryological experiment with rats aboard the space "shuttle" suggests that immobilization is more baneful for the mother-fetus system than microgravity of the same length.

[The effect of unfavorable environmental factors on the mother-fetus system]

The paper provides a generalization of data and the results of own experiments with Wistar rats in the conditions of hypokinesia, immobilization, water deprivation, hypergravity, weightlessness and other factors affecting mother and fetus as a system. It gives a comparison of reactivity of pregnant and non-pregnant animals under stress, and also of the effects of unfavorable impacts sustained during various phases of ontogenesis: in pubertation period, directly before pregnancy and during various phases of pregnancy. It demonstrated that exposition of pregnant animals to unfavorable conditions is accompanied by significant stress of the compensatory-adaptive possibilities of mother aiming to support of homeostasis of the developing fetus. Clear changes develop in fetus only in case the adaptive possibilities of mother turn out inadequate or when the developing organs of fetus become active components of adaptive reaction of mother-fetus system and compensate for functional inadequacy of some mother's organ. The paper discusses the problem of individual features of resistivity and reactivity.

Developmental toxicities of methacrylic acid, ethyl methacrylate, n-butyl methacrylate, and allyl methacrylate in rats following inhalation exposure

The developmental toxicities of 4 methacrylates were studied in Sprague-Dawley rats after inhalation exposure for 6 h/day, during days 6 to 20 of gestation. The exposure concentrations were, for methacrylic acid, 0, 50, 100, 200, or 300 ppm; for ethyl methacrylate, 0, 600, 1200, 1800, or 2400 ppm; for n-butyl methacrylate, 0, 100, 300, 600, or 1200 ppm; and for allyl methacrylate, 0, 12, 25, 50, or 100 ppm. No significant increases in embryo/fetal lethality or fetal malformations were observed after exposure to any of these methacrylates. Fetal toxicity evidenced by statistically significant decreases in fetal body weights was observed at exposure levels > or = 1200 ppm ethyl methacrylate, > or = 600 ppm n-butyl methacrylate, and at 100 ppm allyl methacrylate. Statistically significant increases in the incidence of fetuses with skeletal variations and of fetuses with any variations were noted at 1200 ppm n-butyl methacrylate. These developmental effects were observed in the presence of overt signs of maternal toxicity. While maternal toxicity was observed, methacrylic acid caused no evidence of developmental toxicity up to 300 ppm.

Developmental toxicity studies of 2-(difluoromethyl)-dl-ornithine (DFMO) in rats and rabbits

DFMO, an irreversible inhibitor of ornithine decarboxylase (ODC), is under development as a chemopreventive drug against cancers with pronounced proliferative phases. In support of human clinical trials, preclinical developmental toxicity studies were conducted in pregnant rats and rabbits. Rats were treated during GD 6-17, and fetuses were obtained by C-section on GD 20. Rabbits were treated during GD 7-20, and fetuses were obtained by C-section on GD 29. The dose range-finding study in rats (5/group at 0, 50, 125, 300, 800, or 1000 mg/kg/day) revealed maternal toxicity at doses > or = 800 mg/kg/day (decreased body weights and food consumption) and developmental toxicity at doses > or = 300 mg/kg/day (increased early resorptions and reduced fetal body weights). In the main study, rats (25/group) received 0, 30, 80, or 200 mg/kg/day. Developmental toxicity in the absence of maternal toxicity was observed at 200 mg/kg/day as significantly decreased fetal weights and increased incidence of litters with skeletal variations of 14th rudimentary rib, 14th full rib, and/or 27th presacral vertebrae. There were no treatment-related fetal skeletal malformations or external or visceral anomalies at any dose level. The dose range-finding study in rabbits (5/group at 0, 30, 60, 120, 240, or 500 mg/kg/day) revealed developmental toxicity at doses > or = 60 mg/kg/day (increased resorptions and reduced fetal body weights) in the absence of maternal toxicity. In the main study, rabbits (20/group) received 0, 15, 45, or 135 mg/kg/day. Developmental toxicity in the absence of maternal toxicity was observed at 135 mg/kg/day as nonsignificantly increased early resorptions, decreased implantation sites, decreased viable fetuses, and reduced fetal weights. There were no external, visceral, or skeletal anomalies at any dose level. Thus, in the main developmental toxicity studies, DFMO produced developmental but not maternal toxicity at 200 and 135 mg/kg/day in rats and rabbits, respectively. Accordingly, in rats, the maternal no-observable-effect level (NOEL) was 200 mg/kg/day and the fetal NOEL was 80 mg/kg/day; while in rabbits the maternal NOEL was 135 mg/kg/day and the fetal NOEL was 45 mg/kg/day. These fetal NOELs are several-fold higher than the dose level currently used in Phase II and III clinical trials (approximately 13 mg/kg).

Blood and brain mercury levels after chronic gestational exposure to methylmercury in rats

Female rats were exposed to 0, 0.5, or 6 ppm Hg (as methylmercuric chloride, 10 rats/group) in drinking water. For half the rats, exposure began 4 weeks before mating and for the others, exposure began 7 weeks before mating. All mating was done with an unexposed male. Maternal exposure continued to post-natal day (PN) 16. Blood and whole-brain mercury concentrations were determined in pups on PN 0 (birth) and PN 21 (weaning). Maternal water consumption was monitored daily during gestation and lactation. Maternal water consumption increased 2- to 3-fold through gestation for all groups. Mercury levels in blood and brain were unrelated to the duration of exposure before mating, although reproductive success appeared to be so related. Mercury levels in both media were closely related to consumption during gestation, but apparently maternal exposure during lactation did not result in exposure to the nursing pups. Brain mercury in offspring decreased between birth and weaning from 0.49 to 0.045 ppm in the low-dose rats and from 9.8 to 0.53 ppm in the high-dose rats. The brain increased in weight only about 5.5-fold during this time, indicating that there was minimal mercury exposure and some net loss from brain during this period. Brain:blood ratios averaged about 0.14 at birth and 0.24 at weaning, suggesting differential loss from neural and non-neural tissue. These ratios are higher than those reported in studies using less chronic exposure conditions or with adult rats. Brain concentrations of mercury in females in the low-dose group were about 10-15% higher than those seen in their male siblings. At the higher dose, the males had slightly higher levels of mercury in the brain than did their female siblings at birth. The relationship between brain concentration (in ppm) and cumulative mercury consumption, also expressed on a ppm basis (cumulative mercury consumed divided by maternal body weight at parturition), was not linear but was well described by a power-function relationship: Hg = A*(cum exposure)b where the exponent, b, was 1.12 and 1.17 for blood and brain, respectively, at birth. This exponent was indistinguishable from 1.0 for both media at weaning, indicating that the relationship between exposure and blood and brain levels became linear.

Maternal dietary choline availability alters mitosis, apoptosis and the localization of TOAD-64 protein in the developing fetal rat septum

Maternal changes in dietary choline availability alter brain biochemistry and hippocampal development in the offspring resulting in lifelong behavioral changes in the offspring. In order to better understand the relationship between maternal diet, brain cytoarchitecture and behavior, we investigated the effects of choline availability on cell proliferation, apoptosis and differentiation in the fetal rat brain septum. Timed-pregnant rats on day E12 were fed AIN-76 diet with varying levels of dietary choline for 6 days. We found that choline deficiency (CD) significantly decreased the rate of mitosis in the progenitor neuroepithelium adjacent to the septum. In addition, we found an increased number of apoptotic cells in the septum of CD animals compared to controls (3.5+/-0.5 vs. 1.7+/-0.5 apoptotic cells per section; p<0.05). However, CD had no effect on apoptosis in the indusium griseum (IG), a region of cortex dorsal to the septum. Using an unbiased image analysis method and a monoclonal antibody we found a decreased expression of the TOAD-64 kDa protein, a marker of commitment to neuronal differentiation during fetal development, in the dorsal lateral septum of CD animals. CD also decreased the expression of TOAD-64 kDa protein in the IG and cortical plate adjacent to the septum. These results show that dietary choline availability during pregnancy alters the timing of mitosis, apoptosis and the early commitment to neuronal differentiation by progenitor cells in regions of the fetal brain septum, as well as hippocampus, two brain regions known to be associated with learning and memory.

Dynamics of fetal circulatory responses to hypoxia and asphyxia

This review will focus on the dynamic changes of the fetal circulation, the distribution of organ blood flow during normoxemia, and that during hypoxia and asphyxia caused by various experimental perturbations. Furthermore, the relation between oxygen delivery and tissue metabolism during oxygen lack as well as evidence to support a new concept will be presented along with the principal cardiovascular mechanisms involved. Finally, blood flow and oxygen delivery to the principal fetal organ will be examined and discussed in relation to organ function. The fetal circulatory response to hypoxaemia and asphyxia is a rapid centralization of blood flow in favour of the brain, heart, and adrenals and at the expense of almost all peripheral organs, particularly of the lungs, carcass, skin and scalp. This response is qualitatively similar but quantitatively different under various experimental conditions. However, at the nadir of severe acute asphyxia the circulatory centralization cannot be maintained. Then there is circulatory de-centralization, and the fetus will experience severe brain damage if not expire unless immediate resuscitation occurs. Future work in this field will have to concentrate on the important questions, what factors determine this collapse of circulatory compensating mechanisms in the fetus, how does it relate to neuronal damage, and how can the fetal brain be pharmacologically protected against the adverse effects of asphyxia?