Placental-specific Igf2 knockout mice exhibit hypocalcemia and adaptive changes in placental calcium transport.

Evidence is emerging that the ability of the placenta to supply nutrients to the developing fetus adapts according to fetal demand. To examine this adaptation further, we tested the hypothesis that placental maternofetal transport of calcium adapts according to fetal calcium requirements. We used a mouse model of fetal growth restriction, the placental-specific Igf2 knockout (P0) mouse, shown previously to transiently adapt placental System-A amino acid transporter activity relative to fetal growth. Fetal and placental weights in P0 mice were reduced when compared with WT at both embryonic day 17 (E17) and E19. Ionized calcium concentration [Ca(2+)] was significantly lower in P0 fetal blood compared with both WT and maternal blood at E17 and E19, reflecting a reversal of the fetomaternal [Ca(2+)] gradient. Fetal calcium content was reduced in P0 mice at E17 but not at E19. Unidirectional maternofetal calcium clearance ((Ca) K (mf)) was not different between WT and P0 at E17 but increased in P0 at E19. Expression of the intracellular calcium-binding protein calbindin-D(9K), previously shown to be rate-limiting for calcium transport, was increased in P0 relative to WT placentas between E17 and E19. These data show an increased placental transport of calcium from E17 to E19 in P0 compared to WT. We suggest that this is an adaptation in response to the reduced fetal calcium accumulation earlier in gestation and speculate that the ability of the placenta to adapt its supply capacity according to fetal demand may stretch across other essential nutrients.

Increased maternofetal calcium flux in parathyroid hormone-related protein-null mice.

The role of parathyroid hormone-related protein (PTHrP) in fetal calcium homeostasis and placental calcium transport was examined in mice homozygous for the deletion of the PTHrP gene (PTHrP-/- null; NL) compared to PTHrP+/+ (wild-type; WT) and PTHrP+/- (heterozygous; HZ) littermates. Fetal blood ionized calcium was significantly reduced in NL fetuses compared to WT and HZ groups at 18 days of pregnancy (dp) with abolition of the fetomaternal calcium gradient. In situ placental perfusion of the umbilical circulation at 18 dp was used to measure unidirectional clearance of (45)Ca across the placenta in maternofetal ((Ca)K(mf)) and fetoplacental ((Ca)K(fp)) directions; (Ca)K(fp) was < 5% of (Ca)K(mf) for all genotypes. At 18 dp, (Ca)K(mf) across perfused placenta and intact placenta ((Ca)K(mf(intact))) were similar and concordant with net calcium accretion rates in vivo. (Ca)K(mf) was significantly raised in NL fetuses compared to WT and HZ littermates. Calcium accretion was significantly elevated in NL fetuses by 19 dp. Placental calbindin-D(9K) expression in NL fetuses was marginally enhanced (P < 0.07) but expression of TRPV6/ECaC2 and plasma membrane Ca2+-ATPase (PMCA) isoforms 1 and 4 were unaltered. We conclude that PTHrP is an important regulator of fetal calcium homeostasis with its predominant effect being on unidirectional maternofetal transfer, probably mediated by modifying placental calbindin-D(9K) expression. In situ perfusion of mouse placenta is a robust methodology for allowing detailed dissection of placental transfer mechanisms in genetically modified mice.

Perinatal outcome of quadruplet pregnancies in relation to chorionicity.

OBJECTIVE: To compare the perinatal outcome of quadruplets in relation to chorionicity. PATIENTS AND METHODS: In this retrospective study, the maternal, neonatal and chorionicity data were collected from 24 sets of quadruplet pregnancies delivered between January 1985 and December 2001. Perinatal and neonatal data were evaluated in relation to chorionicity. RESULTS: Sixteen pregnancies were quadra-chorionic quadramniotic (QC) and eight had at least one monochorionic pair (TC). The median gestational age at delivery was 31 weeks (23 to 34 weeks) with overall perinatal mortality rate of 177 per 1000 total birth. Delivery before 30 weeks (OR 89; 95% CI 9 to 607; P<0.01) and discordant birth weight of >25% (OR 7.6; 95% CI 2 to 29; P<0.01) had independent effects on perinatal loss rate. The perinatal loss was five fold higher in TC quadruplets than those of QC (OR 5.1; 95% CI 1.7 to 15.4; P<0.001). This was attributed to higher risk of very low birth weight (69 vs 13%; P<0.01), delivery before 30 weeks (63 vs 13%; P<0.001) in TC quadruplets compared to QC gestation. CONCLUSIONS: The quadruplets with MC pair have 5 times higher perinatal mortality than quadra-chorionic quadruplet pregnancies owing to preterm delivery and discordant birth weight.

Artificial perfusion of the fetal circulation of the in situ mouse placenta: methodology and validation.

Here we present methodology and validation (including measurement of unidirectional maternofetal clearance (Kmf) of (45)Ca and (14)C-mannitol) for in situ perfusion of the mouse placenta. On day 18 of gestation (term=19 days) mice were anaesthetised and the uterus delivered into a saline bath (40 degrees C). A fetus was selected, the umbilical artery and vein catheterised and perfused with Krebs Ringer (pH 7.4) at 60 microl/min. (45)Ca/(14)C-mannitol (2 microCi/5 microCi in 50 microl saline) was injected via maternal tail vein. Perfusate samples were collected every 5 min for 45 min. Maternal carotid artery pressure was monitored throughout perfusion. A terminal maternal cardiac blood sample was taken and analysed. Placentas were immersion fixed and processed for electron microscopy. Kmf for (45)Ca and (14)C-mannitol was calculated as perfusate [(45)Ca or (14)C-mannitol] x perfusion rate/maternal plasma [(45)Ca or (14)C-mannitol]xplacental weight. Maternal cardiac blood chemistry at termination (n=8-15, mean+/-SEM) was as follows: pH 7.153+/-0.016, PCO(2) 45.48+/-2.06 mmHg, PO(2) 66.47+/-7.10 mmHg, Na(+) 151.4+/-1.2 mmol/l, K(+) 5.54+/-0.17 mmol/l, Ca(2+) 1.15+/-0.03 mmol/l, glucose 7.2+/-0.5 mmol/l, and lactate 1.76+/-0.77 mmol/l. A successful 45 min perfusion in which perfusate recovery was >95% occurred in >50% of animals. Perfusion did not alter placental morphology or carotid pressure. Kmf (microl/min/g placenta) for (45)Ca (66.0+/-8.4 (n=7)) was significantly higher than Kmf for (14)C-mannitol (20.0+/-2.4 (n=5)) (p<0.01). These data demonstrate physiological perfusion of the mouse placenta in situ and its usefulness for measurement of solute transfer.

Electrical potential difference between mother and conceptus in the mouse.

This study aimed to determine whether there is a maternofetal potential difference (PD) in the mouse. The mean (+/- SEM) in vivo electrical potential difference (PD(sa)) between saline filled catheters in the maternal subcutaneous space (s) and the fetal amniotic sac (a) measured, according to strict criteria, in anaesthetised MF1 mice at a gestational age of 18-20 (term 20) days was 3.9+/-0.5 mV (significantly different from zero P<0.0001) in 16 conceptuses from 11 mice with the amniotic sac positive with respect to the maternal catheter. The PD(sv) between maternal tail vein (v) and maternal subcutaneous space was -0.8+/-0.4 mV (n=3: not significantly different from zero). Measurement of PD between two different maternal subcutaneous catheters (n=4) was < or =0.5 mV. This study shows that there is a maternofetal PD in the mouse and provides the foundation for studies addressing its mechanism of generation in this species.

Prospective function of placental leptin at maternal-fetal interface.

Leptin is an endocrine and a growth factor which is important for regulation of body fat, feeding, and energy homeostasis. The anti-obesity function of leptin has been recently extended to reproduction, puberty and pregnancy as an endocrine signal to the hypothalamus. Leptin controls the functional integrity of the feto-placental unit thereby maintaining pregnancy by virtue of its immunomodulatory property via T lymphocytes or other proto-oncogenes. Dysregulation of autocrine/paracrine function of leptin at feto-placento-maternal interface may be implicated in the pathogenesis of recurrent miscarriage gestational diabetes, pre-eclampsia and intra-uterine fetal growth retardation including disturbance of fetal bone turnover. This review will focus on the role of leptin in normal and abnormal pregnancy and fetal growth.

Attention to infants in the first year.

The time spent by 158 infants in contact with their carers at 6, 13, 26 and 52 weeks was reviewed prospectively. Periods of contact in the categories of (1) physical care, (2) holding the crying or sleeping infant, and (3) playing and interacting with the infant were recorded using 24-h log diaries completed by the mother. The mean total carer contact time over a 24-h day did not change significantly in the first year, varying between 6.5 and 73 h. Between 6 and 52 weeks, time spent by the mother in physical care declined significantly from 207 to 143 min and in holding the crying or sleeping infant from 61 to 17 min (P < 0.05 and 0.0001 respectively). There were no significant changes in the amount of time spent in playing and interacting with the infant over the first year by the mother and father, the time being on average 52.7 and 25.0 min respectively. Play and interaction with a non-parental carer increased significantly from 14 to 69 min (P < 0.0001). Relationships between infant size and holding became weaker as the infant became older. Infant gender, socioeconomic status and duration of breast-feeding did not influence infant contact time.

Primitive neuroectodermal tumor of the uterus. A case report.

BACKGROUND: Primitive neuroectodermal tumor (PNET) is a rare tumor derived from fetal neuroectodermal cells. These tumors occur in the central nervous system and in peripheral locations. Histologic diagnosis is the standard since most of these tumors are detected at an advanced stage. CASE: A 17-year-old female presented with persistent vaginal bleeding. Physical examination revealed a 4-cm, hard, barrel-shaped cervix. A cervicovaginal smear was obtained. The specimen was hypercellular, with small to medium-sized, round, malignant cells. A diagnosis of PNET was made from the histologic sections of the surgical specimen. CONCLUSION: When numerous small round cells in a diffuse pattern are seen on a Pap smear, the differential diagnosis is long and difficult. However, with careful evaluation of the cytologic features, a few reasonable differential diagnoses can be reached. Furthermore, with liquid-based Pap smears, material is available for immunohistochemical staining to narrow the range even more. Using all resources, including a good clinical history, a cytopathologist can give the clinician an early diagnosis for intervention and treatment.

Site of catecholamine modulation of feto-maternal electric potential difference in the pig.

Feto-maternal vascular (PD(F-M)) and amniotic maternal (PD(A-M)) potential differences were measured simultaneously on seven occasions in six conscious pigs of 100-106 days gestation. Resting values of PD(F-M) and PD(A-M) were not significantly different although the range was wide. Fetal intravascular injection of 20 microg adrenaline, but not of saline, was associated with a prompt reversible change, of equal magnitude, in both PD(F-M) and PD(A-M). In some experiments polarity was reversed. Feto-amniotic potential difference did not change. There was no change in fetal plasma K+ and Na+ concentrations. Because of the simultaneous and equal alterations in PD(F-M) and PD(A-M) following adrenaline and the anatomical configuration of the pig conceptus, we conclude that the catecholamine modifiable component of PD(F-M) is generated by electrogenesis in the pig placenta, probably by its chorionic (trophoblastic) cell layer.

Fetal and postnatal growth to age 2 years by mother's country of birth.

The objective of this study was to measure the physical growth of fetuses and infants in an inner city health district in the north of England and to compare their growth profiles according to mother's country of birth (British Isles or Indian subcontinent). The study was part of the Central Manchester Child Growth Project, a prospective longitudinal study of fetal and postnatal growth and development in a sample from the geographically-defined Central Manchester Health District. Data were collected from the beginning of the second trimester of pregnancy to the age of 2 years. One-hundred seventy-four singleton infants born at term ( > or = 37 weeks) had serial antenatal cephalometry every 3 weeks from the beginning of the second trimester and had serial head, length and weight measurements at birth and at the ages of 6, 13, 26, 52 and 104 weeks. Infants of Indian-born mothers tended to be lighter at birth than those of locally-born mothers, but the difference was not due to lower accumulation of soft tissue. Body length from 6 to 52 weeks in both groups of infants was similar. The major finding was the reduced head size in infants of Indian-born mothers, the difference being significant among boys, evident from mid-pregnancy and persisting postnatally to age 2 years. Reduced fetal growth is associated with the development of cardiovascular disease in adulthood, mortality from ischaemic heart disease being specifically linked with head size at birth. The reduced head size of boys of Indian-born mothers is of interest because male immigrants from the Indian subcontinent who live in England have an increased incidence of non-insulin dependent diabetes and a substantial excess mortality (standardised mortality ratio 313 at ages 20-29) from ischaemic heart disease.

Duration and pattern of crying in the first year of life.

In a prospective study of fetal and postnatal growth and development in a group of babies whose mothers were residents of an inner-city health district in the north of England, the total amount of crying of 157 infants was recorded at four periods during the first year of life by means of a 24-hour log. The mean number of crying episodes reduced from 4.4 at six weeks to 1.5 at one year. Early crying predicted later crying. It was not possible to predict which babies would cry a lot except that breast-fed infants tended to cry less. Mothers' perceptions of whether their babies cried a lot correlated with their perception of sleep difficulties. Rapid response to crying was associated with significantly less crying overall.

Sleep in the first year of life.

The sleep patterns of 174 infants were recorded on one typical day at six, 13, 26 and 52 weeks of age, using a 24-hour log. During the first year of life the number of episodes of sleep was reduced by about 50 per cent, but total sleep time was reduced by only two hours. A circadian rhythm was established by six weeks of age. Smaller infants slept more than larger ones in the first months of life. Sex or birth-order of the child did not affect the duration or number of sleep episodes, but sleep pattern related significantly to whether or not mothers found their infants difficult to feed. Introduction of weaning food at an early stage reduced the number of sleep episodes, but increased the average length of each episode. Socio-economic status showed no significant relationship with number of episodes or total length of sleep.

Maternofetal potential difference in pigs.

The maternofetal potential difference (PD) between catheters in maternal and fetal blood vessels has been measured in conscious sows between 97 and 107 days of gestation. The maternofetal PD was -18 +/- 4 mV (mean +/- SE, n = 13, fetus negative) on the day of surgery and -29 +/- 5 mV (n = 6) on the day after surgery. Injection of 2, 20, or 200 micrograms of epinephrine into the fetuses caused a marked rapid change in maternofetal PD such that the fetus became less negative and, in some cases, became positive with respect to the mother. The maximum change, obtained with 20 micrograms, was 19.9 +/- 5.6 mV (n = 7); measurements of fetal plasma epinephrine concentrations (using high-performance liquid chromatography) after injection of this dose gave a time 0-extrapolated concentration of 436.5 +/- 169.0 nmol/l (n = 4). Injection of 20 micrograms of the beta-agonist isoprenaline caused a maximum change in PD of 20 +/- 4 mV (n = 6); 2 mg of the alpha-agonist phenylephrine was required to produce a similar change (15 +/- 2 mV, n = 6). Injection of the beta-antagonist propranolol (1 mg) reduced the effect of 20 micrograms epinephrine by 40%. The effect of catecholamine on maternofetal PD is similar in polarity and specificity to that found for transplacental PD in vitro in the same species. There is, however, a difference between resting maternofetal and transplacental PD that remains unexplained.

Sex difference in fetal head growth.

Growth of the fetal biparietal diameter (BPD) throughout the second and third trimesters was measured in a prospective longitudinal study. Linear-cubic equations were fitted to the data of individual fetuses and from these equations mean growth curves were produced for males and females. The head growth trajectories of males and females were significantly different. The study illustrates why the practice of dating pregnancies by ultrasonic fetal BPD measurement at about 16 weeks gestation can lead to error.

Electrical activity and sodium transfer across in vitro pig placenta.

Electrical activity generated by pieces of pig placenta, taken from anesthetized animals and mounted in Ussing chambers, has been investigated. Ten minutes after the start of voltage clamping, potential difference (PD; fetal side positive, open circuit), short circuit current (SCC), and resistance were 5.9 +/- 0.4 (SE) mV, 8.6 +/- 0.5 microA X cm-2, and 720 +/- 45 omega X cm2, respectively (n = 50). Ouabain (10(-4) M) added to the fetal side caused a maximum decline in PD and SCC from the time of addition of -3.7 +/- 0.98 mV and -3.9 +/- 1.4 microA X cm-2 (n = 6); epinephrine (10(-5) M) added to the fetal side caused increases of +1.0 +/- 0.2 mV and +4.0 +/- 1.4 microA X cm-2, respectively (n = 14). Drug concentrations for 50% maximum response for the effect of a series of adrenergic agonists on SCC were (in M) isoproterenol 1.2 +/- 0.05 X 10(-8), norepinephrine 6.1 +/- 0.3 X 10(-8), epinephrine 2.4 +/- 0.1 X 10(-7), and phenylephrine 4.7 +/- 0.2 X 10(-5), suggesting the involvement of fetally oriented beta-adrenergic receptors. Fetal epinephrine (10(-5) M) also stimulated net Na+ flux (Jnet) toward the fetal side to an extent equal to its effect on SCC. In control experiments Jnet was small but was inhibited by fetal side ouabain (10(-4) M) to produce a maternally directed Jnet, significantly different to the SCC. Replacement of Na+ by choline reduced SCC markedly but did not abolish it. In the absence of Na+, epinephrine had no effect on SCC. These results suggest that active Na+ transfer is not completely responsible for the control electrical activity of pig placenta. Epinephrine, however, modulates SCC entirely by stimulating net Na+ transfer toward the fetal side.

Histochemical localization of phosphatases in the pig placenta: II. Potassium-dependent and potassium-independent p-nitrophenyl phosphatases at high pH; relation to sodium-potassium-dependent adenosine triphosphatase.

Histochemical localization by Mg2+ capture methods of K+-dependent, ouabain-sensitive phosphatase activity in the pig placenta shows that strong Na+,K+-dependent adenosine triphosphatase (Na+,K+-ATPase) activity is restricted to the basal zone of the columnar epithelium covering the areolar chorionic villi. It is proposed that active Na+ absorption at this epithelium may be the source of the ouabain-sensitive, fetal-side-positive potential difference which can be measured across the placental membrane in vitro. The one-step procedure for Na+,K+-ATPase localization is unsatisfactory in this organ as any specific ATPase reaction is swamped by activity probably attributable to uteroferrin and other non-specific phosphatases.

Histochemical localization of phosphatases in the pig placenta: I. Non-specific phosphatases and their relation to uteroferrin.

The uterine glands, glandular secretions and areolar chorionic epithelium of the pig placenta in late gestation show high levels of histochemical phosphatase activity at acid pH, particularly towards aromatic monophosphates. The properties of this phosphatase allow its identification with the placental iron carrier protein, uteroferrin, rather than with lysosomal acid phosphatase. Alkaline phosphatase activity is restricted to the microvasculature on the maternal side of the placenta and is entirely distinct from uteroferrin phosphatase activity.

Cellular growth of the placenta in twin pregnancy late in gestation.

In order to establish the pattern of cellular growth in placentae from human twin pregnancy, the total placental concentrations of deoxyribonucleic acid (DNA) and protein were determined. Twin placentae from 31 to 40 weeks' gestation were analysed from 40 pregnancies whose precise gestational ages were known. The study has shown that nuclear multiplication continues until placental growth in weight itself comes to an end. Increase in placental weight was caused by cellular hyperplasia without hypertrophy.