Histidine transfer across the human placenta: characteristics in the isolated perfused human placenta and the effect of ethanol

Histidine is essential to normal fetal growth. In vivo, the fetal-to-maternal (F-to-M) plasma concentration ratio for histidine is the highest of any amino acid. Previously, we have shown that histidine uptake by human placental microvillous membrane vesicles (MMV) occurs by a specific, Na(+)-dependent system. In this study, we have examined the maternal-to-fetal (M-to-F) transfer characteristics of histidine, using the isolated perfused human placental cotyledon. In addition, the effect of ethanol on net transfer of histidine in this human tissue model has been assessed. During 4 h of perfusion a 1.8:1 fetal-to-maternal perfusate ratio formed for histidine. In the perfused placentae, net M-to-F transfer of histidine was saturable with an apparent Km of 0.09 mM. The perfusion experiments suggest that the F-to-M histidine gradient observed in vivo is due primarily to active transport across the placenta. The presence of 300 per cent (65 mM) ethanol in the maternal perfusate did not alter the transfer characteristics of histidine, nor that of the diffusion markers, antipyrine and L-glucose.

[Late gestosis as a compensation mechanism in fetal growth retardation and its disruption by antihypertensive therapy]

A study of the clinical course of severe pre-eclamptic toxemias shows that, in case of antihypertensive therapy, it is usually necessary to terminate the pregnancy in cases of foetal maldevelopment, in cases with foetal indication (if no intrauterine death of the foetus takes place), whereas if there is no maldevelopment it is usually a maternal indication that enforces before-term termination of pregnancy. In case of foetal maldevelopment, a drop in HPL and oestriol values was seen. This suggests that the foetal condition deteriorates under antihypertensive treatment. For the foetus, which is deficiently supplied by the placenta, pre-eclamptic toxaemia is a regulatory mechanism of circulation that enhances blood supply of the placenta, since the peripheral resistance in the placental circulation, which is free from vascular nerves, is lower than in the nerve-supplied circulation of the body, on which a hypertensive substance can act. The assumption that such a compensatory mechanism exists is supported by a number of clinical observations. This regulation, which is necessary for the development and perhaps also for the survival of the foetus, is disturbed by the antihypertensive therapy, which explains the deterioration in the condition of the foetus.

Effect of oral cadmium exposure during pregnancy on maternal and fetal zinc metabolism in the rat

To study the effect of cadmium exposure on maternal and fetal zinc metabolism, rats were exposed to 0, 5, 50, or 100 ppm Cd in the drinking water on Days 6 through 20 of pregnancy. In comparison to controls, fetal and maternal weights were slightly reduced in the 50- and 100-ppm groups, but not the 5-ppm group. Multiple regression analysis revealed that in the 50-ppm group, but not in the 100-ppm group, the decrease in fetal weight was not solely a consequence of decreased maternal weight. Cd accumulated in a dose-dependent manner in both maternal organs and fetuses, although the absolute concentrations in fetuses were very low as compared to those of maternal tissues. In the 50- and 100-ppm groups, zinc concentrations were significantly increased in maternal liver and kidney, and significantly decreased in fetal liver. The changes in tissue Zn concentrations were accompanied by altered Zn-metalloenzyme activities in both maternal and fetal tissues. These findings support the hypothesis that Cd-induced maternal zinc retention is responsible for fetal Zn deprivation and impaired fetal growth.

Influence of caffeine administered during pregnancy on the early differentiation of fetal rat ovaries and testes

In this manuscript it is demonstrated that caffeine when administered to the rat (30 mg/kg per day) during pregnancy affected certain aspects of normal sexual differentiation of the fetal gonads. In the male fetus caffeine was shown to significantly inhibit differentiation of the interstitial tissue and Leydig cells. A significant decrease in the number of Leydig cells exhibiting 3 beta-hydroxysteroid dehydrogenase activity, and consequent reduction in testosterone biosynthesis in the fetal testes at day 15 and day 16 of gestation was found. While the beginnings of Leydig cell function was first seen in the afternoon of the 14th day of gestation in both the experimental and control groups, the adverse effects became marked by 15 days and extreme by 16 days. With the aid of the scanning electron microscope it was observed that caffeine also had an effect on the earlier morphogenic organisation of the seminiferous cords at 13 days of gestation where the aggregation of the Sertoli cells forming the seminiferous cords, was marginally advanced in the control group. However the treated group had caught up by 14 days of gestation. In the female fetus scanning electron microscope studies revealed that in the control and caffeine treated groups the early phase of ovarian differentiation and the later 20 day ovaries were similar in morphology, tissue arrangement and overall appearance. It was also seen that chronic caffeine exposure did not affect the rate of early mitotic proliferation of germ cells, nor later in development the numbers entering meiosis. At 20 days of gestation the numbers and proportion of meiotic to atretic oocytes were comparable in the control and treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Perinatal outcome associated with PCP versus cocaine use

Phencyclidine (PCP) remains a widely used illicit drug, especially among adolescents and young adults. The pharmacologic effects of PCP are similar to those of cocaine; therefore, in this retrospective study 37 PCP-intoxicated parturients were matched for ethnicity, tobacco use, age, gravidity, and degree of prenatal care with 37 cocaine-intoxicated parturients. Infants exposed to PCP in utero, like those exposed to cocaine, had a high incidence of intrauterine growth retardation (32 vs 19%, N.S.), precipitate labor (43 vs 27%, N.S.), symptoms of neonatal drug withdrawal/intoxication, and prolonged neonatal hospitalizations. Moreover, they were more likely to have meconium-stained amniotic fluid (30 vs 19%, p = .05) and less likely to be born prematurely as cocaine-exposed infants. The comparison between the long-term developmental outcome of these groups awaits further study.

Fetal and maternal cocaine levels peak rapidly following intragastric administration in the rat

On gestation day 22, plasma levels of cocaine and its metabolite, benzoylecgonine (BE), were determined over 90 min following either 30 or 60 mg/kg cocaine given via intragastric intubation to Wistar rats which had been given daily cocaine intubations since day 8 of pregnancy. Cocaine levels peaked at 15 min in both the maternal and fetal circulations. Sixty mg/kg produced a peak plasma level of 5384 +/- 594 ng/ml in the dam and 2966 +/- 503 ng/ml in the fetus. Maternal levels of cocaine were higher than fetal levels for the first fifteen min. Thereafter, maternal levels decreased more quickly than fetal such that at 30-90 min, fetal levels were higher than maternal levels. Cocaine levels also peaked at 15 min in fetal brain. At 90 min, however, fetal brain had between 26 and 42% more cocaine than fetal plasma. Therefore, fetal brain exposure to cocaine is somewhat prolonged. BE levels were less predictable. Together, these data indicate that the intragastric route of administration results in rapid uptake of cocaine by blood and produces highly reproducible, pharmacologically relevant levels of cocaine in maternal and fetal plasma and brain. In addition, the placenta does not act as a barrier to the delivery of cocaine to the fetus.

Modulation of pulmonary bombesin by nicotine and vagotomy

In pregnant hamsters, three transplacental injections of the ganglionic agonist nicotine resulted in a dose-dependent decrease in the concentration of mammalian bombesin (MB) in the lungs of neonatal (1 day old) animals. This decrease in neonatal MB did not occur if nicotine was given only once during gestation, or when it was given three times in conjunction with the ganglionic antagonist mecamylamine. In one week old animals born of mothers who had been exposed to three doses of nicotine during gestation, lung MB had returned to control levels. When nicotine was injected into neonatal animals, lung MB acutely increased. Right sided vagotomy to young hamsters resulted in an increase in the ratio of lung MB (right vs. left lobe) 1 week after surgery. Administration of nicotine to vagotomized animals resulted in decreased total lung MB and normalization of the MB ratio. Thus, nicotine has a potent modulatory influence on lung MB during fetal and neonatal development and maturation. This influence is also present in young animals that are subjected to partial denervation. Our hypothesis is that the innervation of pulmonary neuroendocrine (PNE) cells influences both PNE cell growth and its synthetic function. PNE MB, which is an epithelial and neoplastic growth factor, may play a role in this response.

Teratogenic evaluation of tributyltin chloride in rats following oral exposure

The teratogenicity of tri-n-butyltin chloride (TBTC1) was examined in Wistar rats. The pregnant rats were administered orally 25, 15, 9, 5 and 0(Control) mg of TBTC1/kg of body weight/day from day 7 to 15 of pregnancy. Maternal toxicity, as evidenced by both of decreased body weight gain and food consumption was observed at 25, 15 and 9 mg/kg/day dose group. However, only in the 25 mg/kg/day dose group some clinical signs of toxicity (sedation, diarrhoea and salivation) were observed and 70 percent of the dams were dead. In the 25 mg/kg/day dose group, all fetuses were dead. Statistically significant reductions in the female fetal body weight were observed in 9 and 5 mg/kg/day dose groups. In all groups treated with TBTC1 except the 25 mg/kg/day dose group, no significant differences in the numbers of live fetuses and intrauterine death (dead fetuses and resorptions) or sex ratios of fetuses were found between the TBTC1-treated and control groups. Fetal external, skeletal and internal malformations were not observed at any of the dose levels. However, several types of skeletal and internal variations including delayed ossifications were observed in some groups treated with TBTC1, but the incidences were not significantly different from controls. Also, two fetuses with dilatation of the renal pelvis were found in 9 and 5 mg/kg/day dose group. Statistically significant increases of placental weight in all TBTC1-treated groups were observed when compared to that of control group. In conclusion, TBTC1 administered orally to Wistar rats during days 7-15 of pregnancy produced related signs of fetal toxicity but no evidence of teratogenicity and induced a marked increase in placental weight.

Effect of maternal vitamin-A administration on fetal lung vitamin-A stores in the perinatal rat

Vitamin A (retinol) is essential for normal differentiation and integrity of developing respiratory epithelium and its deficiency has been linked to an increased susceptibility to lung injury. Because significant vitamin-A storage occurs in the fetal lung near term in the perinatal rat, prematurely born animals deprived of adequate stores in their lungs may be susceptible to the adverse effects of vitamin-A deficiency. It would be desirable if lung vitamin-A stores could be augmented with maternal administration, but the feasibility of this strategy has not been reported. We therefore conducted this study in rats to determine whether maternal administration of vitamin A could increase the lung stores of vitamin A in the offspring. Vitamin-A-sufficient pregnant rats were given a single dose of either vitamin A (50,000 IU retinyl palmitate) or 0.9% saline solution on gestational day 16 (term = 21 days) by the intragastric route. High-performance liquid chromatography was used to measure concentrations of vitamin A and its esters in fetal and neonatal lungs and livers at times ranging from gestational day 17 through 21, and from postnatal day 1 through 14. The concentrations of vitamin-A esters in the lungs of fetuses and newborn pups of the vitamin-A-treated animals were significantly (1.7- to 7.1-fold) higher than those of the control group. This increase in the lung vitamin-A ester concentrations was seen within 24 h of maternal administration and persisted throughout the 14-day postnatal period.(ABSTRACT TRUNCATED AT 250 WORDS)

Health and development of 8-year-old children whose mothers abused amphetamine during pregnancy

Sixty-five children whose mothers were addicted to amphetamine during pregnancy were followed prospectively until eight years of age, when they were tested in their homes. Only 21 children (30%) remained in the custody of their biological mothers. Their physical health, including growth, was normal. Their IQ and their performance in several psychometric tests were within normal limits. Increased incidences of aggressive behaviour and peer-related problems were found, especially in the groups that had been exposed to amphetamine throughout pregnancy. No correlation was found with socio-environmental factors.

A controlled oximetric evaluation of inhalational, opioid and epidural analgesia in labour

The effects on patient oxygenation of nitrous oxide, narcotic and epidural analgesia in labour were evaluated using pulse oximetry. Five groups of ten patients received either no analgesia (Control, Group 1), an epidural block alone (Group 2), nitrous oxide in oxygen alone (Group 3), intramuscular pethidine (Group 4), or nitrous oxide in oxygen combined with intramuscular pethidine (Group 5). Derived parameters included the maximum (MAX), minimum (MIN), average maximum (AV MAX), and average minimum (AV MIN) arterial haemoglobin oxygen saturation (SaO2), and differences between maxima and minima (MAX-MIN). There was a statistically significant difference between Group 1 and Group 5 for MIN, AV MIN and MAX-MIN SaO2 (P less than 0.05). All other groups showed no significant difference in any parameter when compared with the control group. The results are discussed with reference to normal and disordered maternal physiological changes in pregnancy. It is suggested that nitrous oxide should not be used for analgesia in labour where there is concern about maternal, placental or foetal reserve.

The placental and mammary transport of [14C]menaquinone-4 in rats

The transfer of menaquinone-4 (vitamin K2(20] to the fetus and milk was studied in pregnant and lactating rats, respectively, after oral administration (4 mg/kg) of [3'-14C]menaquinone-4. Intestinal absorption of menaquinone-4 was rapid and the highest level of radioactivity in each tissue except guts of fetal rats was observed at 4h after dosing. The level in the fetal homogenate was low. At that time, the concentration of menaquinone-4 in the fetal liver was 84 ng/g, corresponding to 9% of the value found in the placenta. Therefore, we conclude that the transfer of menaquinone-4 to the developing rat fetus is restricted by the blood-placenta barrier, but that a sufficient amount of menaquinone-4 (more than the essential amount of vitamin K to ensure full carboxylation) can be transferred into the fetal liver. It was also observed that the radioactivity was transferred to milk after oral administration to lactating rats. Milk/blood concentration ratios at 6 and 24h after dosing were 13.8 and 65.1, respectively. The elimination half-life of radioactivity in milk was about 17h. Eighty-four percent of milk of radioactivity was due to menaquinone-4. These results suggest that the prophylactic maternal oral administration of menaquinone-4 may be efficacious for a prophylaxis of neonatal and infantile vitamin K deficiency.

Does insulin affect placental glucose metabolism and transfer?

An in vitro recycled perfusion of the human placenta was used to investigate the effect of insulin on placental metabolism and transfer of glucose. Human insulin, 1000 microU/ml, was introduced into either maternal or maternal and fetal compartments. In one series of experiments placentas were used as either a control group or study group, whereas in the other series each placenta served as its own control. Metabolic effects were determined by measuring placental glucose and oxygen consumption and lactate production rate. The effect of insulin on transfer was studied by the use of 3-O-methylglucose labeled with tritium; this effect was expressed as the slope of maternal minus fetal concentrations on a natural logarithmic scale and compared with the antipyrine tagged with carbon 14. The stability of perfusate volume was used as an index for placental integrity, whereas absence of tissue edema demonstrated adequacy of perfusion. Neither of the metabolic parameters studied was significantly affected by insulin, and insulin did not have an effect on 3-O-methylglucose transfer rate. It was concluded that, in contrast to other tissues in the body, placental glucose metabolism and transfer are not sensitive to the action of insulin.

Amiloride reduces maternofetal clearance of sodium across the near-term rat placenta

The effect of amiloride on unidirectional maternofetal clearance across the perfused placenta has been studied in rats at 21 days gestation. A bolus dose of 1 mg kg-1 followed by an infusion of 0.6 mg h-1 into the maternal circulation caused a significant (P less than 0.02) decrease in 22Na clearance by 8%, whilst having no effect on the clearance of 51Cr-EDTA; a ten times higher dose of amiloride (10 mg kg-1, 6 mg h-1) did not reduce 22Na clearance further. Similar administration of an equivalent volume of saline to control animals showed no effect on either Na+ or Cr-EDTA clearances.

Effects of centrophenoxine on cholinephosphotransferase activity in maternal and fetal guinea pig lung

Cholinephosphotransferase activities of guinea pig lung mitochondria and microsomes are inhibited by centrophenoxine and one of its metabolites, p-chlorophenoxyacetate. 2-Dimethylaminoethanol, the second metabolite of centrophenoxine, has no inhibitory effect on the enzyme activity. The inhibition of enzyme activity by centrophenoxine is noncompetitive. Intravenous injection of centrophenoxine and p-chlorophenoxyacetate to pregnant animals causes inhibition of cholinephosphotransferase activity in adult lung but not in fetal lung. However, direct administration of centrophenoxine to the fetus after laparotomy causes inhibition of both subcellular enzyme activity in fetal lung. It is suggested that the drug injected to the pregnant animals does not reach the fetal lung or is metabolized. Furthermore, while centrophenoxine injection does not change the total phosphatidylcholine content of adult lung, the acyl group composition of phosphatidylcholine was modulated.

The effect of thyroxine, 3, 5-dimethyl-3'isopropyl-L-thyronine and iodized oil on fetal brain development in the iodine-deficient sheep

Studies have been carried out to investigate the role of maternal and fetal thyroid function in the effects of iodine deficiency on fetal brain development in sheep. Iodine deficiency was established with an especially prepared low-iodine diet of maize and pea pollard. The iodine-deficient sheep were mated and the end of the second trimester of pregnancy (100 days gestation) were divided into groups which received either a sc injection of T4 or 3,5-dimethyl-3-isopropyl-L-thyromine or an injection of iodized oil. AT 140 days gestation (10 days prior to parturition) comparison of the fetuses delivered by hysterotomy revealed that the retarded fetal brain development observed in iodine deficiency was greatly improved by T4 and by iodized oil. However, T4 and iodized oil failed to correct the reduction in the number and the increase in the length of synaptic appositions which were observed in the fetal cerebral cortex after iodine deficiency. In addition, the histological appearance of the fetal thyroid gland and the levels of plasma thyroid hormones were restored to normal. The administration of 3,5-dimethyl-3'-isopropyl-L-thyronine had no effect on the retarded fetal brain and body development of the iodine-deficient fetuses. The lack of response may be due to the ability of 3,5-dimethyl-3'-isopropyl-L-thyronine to cross the ovine placenta as no reduction in the abnormally elevated fetal plasma TSH observed in spite of a fall in maternal plasma TSH and apparent restoration of maternal thyroid function.(ABSTRACT TRUNCATED AT 250 WORDS)

Foetal and neonatal exposure to aflatoxins

Studies on 125 primigravidae in rural Kenya revealed aflatoxins in the blood of 54 prenatally. At delivery re-examination of 34 showed aflatoxins in 12 previously negative. The overall detection rate was 53%. Blood from additional 59 women collected at delivery showed aflatoxins in 53%. Aflatoxins were detected in 37% of 101 cord bloods. There was no relationship between aflatoxins in maternal and cord bloods. The frequency of detection was significantly higher in maternal and cord bloods during the 'wet' than 'dry' months. The mean birth weights of females born to aflatoxin positive mothers was significantly lower (255 g) than those born to aflatoxin free mothers. Two stillbirths were recorded, in both cases maternal and cord blood showed aflatoxins. These findings and the adverse effects of prenatal aflatoxin exposure recorded in animal experiments indicate the need for further study of the effects of aflatoxins on the human foetus and newborn.

Risks to the fetus of anticoagulant therapy during pregnancy

The use of anticoagulants during pregnancy is problematic because of the potential adverse effects to the mother and the fetus. Heparin does not cross the placenta, and thus, it was surprising that a recent report concluded that heparin therapy during pregnancy was as risky as oral anticoagulant therapy. Therefore, we performed a literature review of fetal/infant outcomes following anticoagulant therapy during pregnancy. We examined 186 reports which described fetal/infant outcomes in 1,325 pregnancies associated with anticoagulant therapy. The rates of adverse fetal/infant outcomes including death, prematurity and cogenital malformations following treatment with heparin, oral anticoagulants, or both were calculated. The previously described high rate of adverse fetal/infant outcomes with heparin-treated patients, could be accounted for by the frequent use of heparin in pregnancies with comorbid conditions independently associated with adverse outcomes and by reports of uncomplicated prematurity. After excluding such pregnancies, outcomes in heparin-treated patients are similar to the normal population.