Efficiency of various bile salt preparations for stimulation of Clostridium difficile spore germination.

Taurocholate, desoxycholate, and cholate stimulated germination of Clostridium difficile spores in broth medium and enhanced recovery of C. difficile spores on a selective agar medium. Desoxycholate and some crude taurocholate preparations also inhibited multiplication of vegetative cells. At a concentration of 1.2 X 10(-2) M, sodium cholate inhibited multiplication of vegetative cells, but at concentrations of 1.2 X 10(-3) to 2.4 X 10(-3) M, it stimulated germination without inhibiting cell multiplication. Thus, pure sodium taurocholate and sodium cholate may effectively be incorporated in cefoxitin-cycloserine-fructose agar, whereas some crude preparations of sodium taurocholate decrease recovery on this medium.     

Effect of sodium taurocholate on secretion by amphibian gastric mucosa in vitro

Effects of sodium taurocholate on the electrical and secretory activity of amphibian gastric mucosa have been studied in vitro. Exposure of the luminal surface of fundic mucosa to high concentrations (5 X 10(-2) M) at low pH (2.0 and 3.0) produced a marked fall in potential difference and electrical resistance. At lower concentrations (10(-3) to 10(-4) M) and higher pH (7.4), taurocholate did not alter the electrical properties but significantly increased net acidification from 1.39 +/- 0.27 to 2.01 +/- 0.18 mueq . cm-2 . h-1 (means +/- SE; P less than 0.01). Pretreatment of fundic mucosa with cimetidine resulted in net alkaline secretion (0.27 +/- 0.07 mueq . cm-2 . h-1), and addition of taurocholate (10(-4) M) to the luminal surface at pH 7.4 converted net alkalinization to net acidification (0.94 +/- 0.28 mueq . cm-2 . h-1). This response was not inhibited by atropine (10(-5) M) or somatostatin (10(-6) M) but exhibited marked tachyphylaxis. Taurocholate (10(-4) M) inhibited alkaline secretion in thiocyanate-treated fundic mucosa (0.63 +/- 0.04 to 0.14 +/- 0.09 mueq . cm-2 . h-1; P less than 0.001) and in spontaneously alkaline-secreting antral mucosa (0.36 +/- 0.12 to 0.09 +/- 0.06 mueq . cm-2 . h-1; P less than 0.05), but acidification did not occur. Apparent stimulation of acid secretion and simultaneous inhibition of alkaline secretion of sodium taurocholate may play a role in the pathogenesis of mucosal damage by bile.     

Fetal porcine ventral mesencephalon graft. Determination of the optimal gestational age for implantation in Parkinsonian patients

Human fetal ventral mesencephalon tissue has been used as dopaminergic striatal implants in Parkinsonian patients, so far with variable effects. Fetuses from animals that breed in large litters, e.g., pigs, have been considered as alternative donors of dopaminergic tissue. The optimal gestational age of the porcine fetal donors has not been studied systematically. We collected ventral mesencephalic (VM) tissue from fetal pigs, embryonal ages E21, E28, E42, and E70, and examined the viability of the fetal VM cells after dissociation, the expression of tyrosine hydroxylase (TH) in culture, the presence of catecholamines, and the cellular survival and outgrowth up to 10 months after intrastriatal implantation in rats. The highest viability was found in suspensions prepared from E28 fetuses. The highest number of TH-positive cells was found in cell cultures prepared from E28 VM tissue. Explants with a gestational age of 28 and 42 days contained the largest amount of dopamine. Only E28-derived grafts showed TH-cell survival after implantation in rat striatum. Our results show that a gestational age of 28 days must be considered to be the optimal age for dopaminergic tissue derived from pig fetuses for therapeutic use as intrastriatal grafts in Parkinsonian patients.     

Increased uncoupling protein-2 mRNA abundance and glucocorticoid action in adipose tissue in the sheep fetus during late gestation is dependent on plasma cortisol and triiodothyronine

The endocrine regulation of uncoupling protein-2 (UCP2), an inner mitochondrial protein, in fetal adipose tissue remains unclear. The present study aimed to determine if fetal plasma cortisol and triiodothyronine (T₃) influenced the mRNA abundance of UCP2, glucocorticoid receptor (GR) and 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) and 2 (11βHSD2) in fetal adipose tissue in the sheep during late gestation. Perirenal–abdominal adipose tissue was sampled from ovine fetuses to which either cortisol (2–3 mg kg⁻¹ day⁻¹) or saline was infused for 5 days up to 127–130 days gestation, or near term fetuses (i.e. 142–145 days gestation) that were either adrenalectomised (AX) or remained intact. Fetal plasma cortisol and T₃ concentrations were higher in the cortisol infused animals and lower in AX fetuses compared with their corresponding control group, and increased with gestational age. UCP2 and GR mRNA abundance were significantly lower in AX fetuses compared with age-matched controls, and increased with gestational age and by cortisol infusion. Glucocorticoid action in fetal adipose tissue was augmented by AX and suppressed by cortisol infusion, the latter also preventing the gestational increase in 11βHSD1 mRNA and decrease in 11βHSD2 mRNA. When all treatment groups were combined, both fetal plasma cortisol and T₃ concentrations were positively correlated with UCP2, GR and 11βHSD2 mRNA abundance, but negatively correlated with 11βHSD1 mRNA abundance. In conclusion, plasma cortisol and T₃ are both required for the late gestation rise in UCP2 mRNA and differentially regulate glucocorticoid action in fetal adipose tissue in the sheep during late gestation.     

Effect of maternal nutrient restriction in early gestation on responses of the hypothalamic-pituitary-adrenal axis to acute isocapnic hypoxaemia in late gestation fetal sheep

Epidemiological and experimental evidence suggests that maternal undernutrition during pregnancy may alter development of fetal organ systems. We have demonstrated previously that fetal hypothalamic-pituitary-adrenal (HPA) axis responses to exogenous corticotropin-releasing hormone (CRH) + arginine vasopressin (AVP), or adrenocorticotrophin hormone (ACTH), are reduced in fetuses of mildly undernourished ewes. To examine these effects further we tested HPA axis responses to acute isocapnic hypoxaemia in fetal sheep at 114-129 days gestation (dGA), following 15% reduction in maternal nutritional intake between 0 and 70 dGA. Fetuses from control (C) and nutrient-restricted (R) ewes were chronically catheterised and plasma ACTH and cortisol responses were determined at 114-115, 120-123 and 126-129 dGA during hypoxaemia (1 h) induced by lowering the maternal inspired O2 fraction (FI,O2). Basal plasma cortisol concentrations and HPA axis responses at 114-115 and 120-123 dGA did not differ between C and R fetuses. At 126-129 dGA, both plasma ACTH (P < 0.01) and cortisol (P < 0.05) responses were smaller in R fetuses compared to C fetuses. Fetal blood gas status, fetal body weight, body proportions and organ weights did not differ between the groups. We conclude that mild maternal undernutrition alters development of the fetal HPA axis producing a reduction in pituitary and adrenal responsiveness to endogenous stimuli.     

Role of leptin in the regulation of growth and carbohydrate metabolism in the ovine fetus during late gestation

Leptin is an important regulator of appetite and energy expenditure in adulthood, although its role as a nutritional signal in the control of growth and metabolism before birth is poorly understood. This study investigated the effects of leptin on growth, carbohydrate metabolism and insulin signalling in fetal sheep. Crown–rump length-measuring devices and vascular catheters were implanted in 12 sheep fetuses at 105–110 days of gestation (term 145 ± 2 days). The fetuses were infused i.v. either with saline (0.9% NaCl; n = 6) or recombinant ovine leptin (0.5–1.0 mg kg⁻¹ day⁻¹; n = 6) for 5 days from 125 to 130 days when they were humanely killed and tissues collected. Leptin receptor mRNA and protein were expressed in fetal liver, skeletal muscle and perirenal adipose tissue. Throughout infusion, plasma leptin in the leptin-infused fetuses was 3- to 5-fold higher than in the saline-infused fetuses, although plasma concentrations of insulin, glucose, lactate, cortisol, catecholamines and thyroid hormones did not differ between the groups. Leptin infusion did not affect linear skeletal growth or body, placental and organ weights in utero . Hepatic glycogen content and activities of the gluconeogenic enzymes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase in the leptin-infused fetuses were lower than in the saline-infused fetuses by 44, 48 and 36%, respectively; however, there were no differences in hepatic glycogen synthase activity or insulin signalling protein levels. Therefore, before birth, leptin may inhibit endogenous glucose production by the fetal liver when adipose energy stores and transplacental nutrient delivery are sufficient for the metabolic needs of the fetus. These actions of leptin in utero may contribute to the development of neonatal hypoglycaemia in macrosomic babies of diabetic mothers.     

Developmental regulation of hepatic and renal gluconeogenic enzymes by thyroid hormones in fetal sheep during late gestation

Tissue glucose-6-phosphatase (G6P) and phosphoenolpyruvate carboxykinase (PEPCK) activities were investigated in sheep fetuses after experimental manipulation of thyroid hormone status. Increments in hepatic and renal G6P and PEPCK activities seen between 127–130 and 140–145 days of gestation (term, 145 ± 2 days) were abolished when the normal prepartum rise in plasma triiodothyronine (T₃), but not cortisol, was prevented by fetal thyroidectomy (TX). At 127–130 days, hepatic and renal G6P, and renal PEPCK, activities were similar in intact and TX fetuses; however, hepatic PEPCK was increased by TX. At 140–145 days, tissue G6P and PEPCK activities in TX fetuses were lower than in intact fetuses. In immature fetuses infused with cortisol (2–3 mg (kg body wt) ⁻¹ day ⁻¹) for five days, hepatic and renal enzyme activities were increased to those seen in mature fetuses near term. After five days of T₃ infusion (8–12 μg (kg body wt) ⁻¹ day ⁻¹), G6P and PEPCK activities in the liver and kidney were greater than in saline-infused fetuses, but only renal G6P and PEPCK increased to the level seen close to term. Therefore, in fetal sheep, thyroid hormones are important for the prepartum rises in G6P and PEPCK activities in the liver and kidney and may mediate, in part, the maturational effects of cortisol.     

Effect of cortisol on blood pressure and vascular reactivity in the ovine fetus.

The aim of this study was to investigate the cardiovascular effects of exogenous cortisol in fetal sheep, (a) between 100 and 120 days of gestation when cortisol production is minimal and (b) after 130 days when endogenous plasma cortisol starts to rise. Chronically cannulated ovine fetuses (103-120 days, n = 9; 130-137 days, n = 7), received sequentially a 24 h infusion of vehicle (0.9% sodium chloride) and a 24 h infusion of cortisol at 100 micrograms/h. Blood pressure and heart rate changes to bolus injections each of angiotensin II and noradrenaline (0.2, 0.5, 1.0, 2.0 micrograms) were measured before and after the saline and cortisol infusions. Fetuses in each age group, served as additional controls receiving 48 h saline infusions. In both immature and mature age groups, the cortisol infusion increased basal fetal blood cortisol concentrations by 33.7 and 35.4 nmol/l respectively. In the immature group, cortisol, but not saline, caused significant 14.3 and 15.3% increases in basal systolic and diastolic pressures respectively. Basal blood pressure was higher in the mature group, but did not increase further despite the increase in cortisol levels. Furthermore, vascular responsiveness to angiotensin II but not to noradrenaline was significantly enhanced following the cortisol infusion, at both ages. Fetal heart rate did not change following the cortisol infusion. Exogenous cortisol contributes to the regulation of fetal blood pressure in the immature fetus, when other mechanisms have not developed. Cortisol might achieve this, in part, by enhancing vascular sensitivity to angiotensin II.     

In utero transmission of Mycoplasma pulmonis in experimentally infected Sprague-Dawley rats.

Genital mycoplasmosis is important as an animal model for the interaction between infectious agents and the host during pregnancy as well as in its own right as a confounding variable affecting research projects in which the rat is used as a model to study reproductive function and physiology. We report the in utero transmission of Mycoplasma pulmonis and the development of placentitis, amnionitis, and mild fetal bronchopneumonia in Sprague-Dawley rats. A minimum of 10 days prior to breeding, specific-pathogen-free female Sprague-Dawley rats were infected by intravaginal inoculation with 3 x 10(7) CFU of M. pulmonis X1048 or with an equal volume of sterile broth. Rats and fetuses were subjected to necropsy at days 11, 14, and 18 of gestation. M. pulmonis was able to invade the placenta, cross the placental barrier, and establish an amniotic fluid infection by gestational day 14. It was isolated from the oropharynx and lungs of fetuses at gestational day 18. The placenta was more frequently colonized than amniotic fluid, followed by the fetal oropharynx and lungs, supporting an ascending route of infection. Histopathological evidence also support an active infection, with lesions compatible with placentitis, amnionitis, and mild fetal bronchopneumonia. M. pulmonis can traverse the placenta, resulting in infection of the amniotic fluid and in utero transmission of the microorganism to the developing fetus.     

Interferon production in murine macrophage-like cell lines

Five murine macrophage (M phi)-like cell lines were examined to determine their suitability for the characterization of M phi interferons (IFNs). The J774A.1, RAW 309 Cr.1, and RAW 264.7 cell lines produced 30-800 international units (IU)/10(6) cells when treated with 5-200 micrograms of bacterial lipopolysaccharide (LPS). No IFN was detected in LPS-treated P388D1 or PU5-1.8 cell cultures. All cell lines produced IFN when inoculated with Newcastle disease virus (NDV); however, only 15 IU/10(6) cells of acid stable IFN were produced in PU5-1.8 cell cultures in comparison to 4.2 X 10(3)-1.7 X 10(4) IU/10(6) cells in the other cell lines. Most of the IFN was produced within 4 h in LPS-treated cell cultures and within 12 h in NDV-infected cell cultures. All IFNs were stable at pH 2.0 and were neutralized with antiserum against mouse L cell IFN. These cell lines appear competent for use in studying the synthesis, molecular weights, and regulatory functions of M phi IFNs.     

Rates of protein synthesis and turnover in fetal life

Uniformly labeled [14C]lysine was infused at constant rate into the inferior vena cava of eight ovine fetuses with gestational ages ranging from 110 to 145 days. The infusion lasted 9 to 13 h and produced a steady-state specific activity of free lysine in the fetal plasma. In the steady state, approximately 9% of the infused radioactivity was excreted by the fetus as 14CO2, indicating fetal catabolism of lysine. At the end of the infusion, the fetal carcass was analyzed for its total content of labeled and unlabeled lysine. The rate of protein synthesis was calculated from the carcass-to-plasma lysine specific activity ratio. The fractional rate constant (Ks) for the unidirectional flux of lysine into fetal proteins was inversely related (r = -0.88) to fetal age: Ks = 0.584 - 0.0036 age (days). In each fetus, Ks was 2-4 times greater than the estimated fractional rate of fetal protein accretion (KG). The discrepancy between Ks and KG demonstrates that a large fraction of protein synthesis in the ovine fetus is devoted to protein turnover.     

Serum hormones and metabolites in fetally decapitated pigs

The effects of fetal decapitation on serum hormones and metabolites were studied in utero in the pig. Pig fetuses were decapitated at 45 days of gestation and serum sampled from the umbilical vein and artery of each fetus and from the uterine artery at 110 days of gestation. Serum levels of cortisol were reduced in decapitated fetuses when compared to intact controls. The data suggest that the decapitated fetus derived its cortisol primarily from maternal sources. Decapitation produced a deficiency of serum RIA growth hormone, T3 and T4. The absence of these hormones produced no effect on fetal growth. Serum insulin, glucagon and triglycerides were elevated in decapitated fetuses. Arterial venous differences in blood glucose indicated that the decapitated fetuses were utilizing glucose at a higher rate than intact fetuses. The alterations seen in serum insulin and triglycerides suggest that neural mechanism may be involved in prenatal lipid deposition.     

Early maturation of force production in pig tracheal smooth muscle during fetal development.

The contractility of airway smooth muscle is fully established at late term at birth but its responsiveness during fetal life has not been defined. In this study, the contractile force of airway smooth muscle to acetylcholine (ACh), K+ depolarizing solution, and electrical field stimulation (EFS) was measured in tracheas from small fetal pigs. Contraction to either agonist and to EFS was detectable in fetuses of as low as 9 g body weight, which corresponds to approximately 36 days of gestation. Isometric force increased progressively with age, reaching 4.1 +/- 0.4 mN for K+ and 5.8 +/- 0.5 mN for ACh (10(-4) M) at 600 g fetal weight (90 days). However, when normalized for cross sectional area of smooth muscle, the stress was essentially the same from 17- to 600-g fetuses. (K+: 17 g = 74.4 +/- 10.6 mN/mm2, 600 g = 89.3 +/- 13.0 mN/mm2; ACh [10(-4) M]: 17 g = 76.3 +/- 16.0 mN/mm2, 600 g = 127.0 +/- 13.0 mN/mm2). The sensitivities of the various groups to ACh were not significantly different (e.g., EC50: 30 g = 4.0 +/- 0.2 x 10(-6) M, 600 g = 3.7 +/- 1.1 x 10(-6) M). EFS produced frequency-dependent contractile responses in all groups. With increasing fetal size, there was a corresponding increase in force. When this force was normalized to a maximum ACh response (10(-4) M), there was no significant difference between groups of fetuses. Histologic examination showed the major tissue components of the trachea were present in fetuses above 7 g. Immunocytochemistry detected myosin, caldesmon, and filamin in the smooth muscle from fetuses of 7 g and above, showing that contractile and actin-binding proteins were present from a very early age. It is concluded that smooth muscle contractile function is well developed very early in fetal life in pigs.     

Growth inhibition of fibroblasts by progesterone and medroxyprogesterone in vitro

This study was carried out to evaluate in vitro the beneficial effects observed in various aggressive fibromatoses (mediastinal, retroperitoneal, paraneoplastic fibrosis and desmoid tumors) after treatment with progesterone. Primary cultures of fibroblasts were prepared from fetuses of Swiss strain mice. Continuous fibroblast lines LM and Vero were also used. Moreover, cultures of non-fetal human fibroblast from skin and lung were employed. Epithelial tumor cell line HeLa was used as a control. All cultures were incubated with various doses of progesterone at concentrations from 1.4 X 10(-4) to 1.4 X 10(-3) M. Human cells and monolayers of fetal murine fibroblast were submitted to the action of medroxyprogesterone solution at the same concentrations as used for progesterone. Other steroids (estrone, estriol, testosterone and prednisolone) were used at the identical concentrations in the same vehicles. Progesterone affected all lines of fibroblasts studied and destroyed them within either 2-4 or 24-48 h depending on the steroid concentrations used. Medroxyprogesterone had a comparable effect on human cell lines and monolayers of fetal murine fibroblasts provided that the same ratio between the hormone concentration and the time of exposure was maintained. With higher medium concentrations shorter times of incubation were required for the destruction of fibroblast. However, to observe a degree of lysis similar to that elicited by progesterone, it was necessary to use 4 times higher concentrations of medroxyprogesterone. No effect on HeLa epithelial cells was observed nor were the controls affected by the steroids or diluents used at the appropriate concentrations. Results from incubation studies using monolayers of murine fibroblast and 14C-progesterone suggested that the cells were destroyed by the progesterone and not by a bioproduct of its metabolism.     

Development of baroreflex function and hind limb vascular reactivity in the horse fetus

This study investigated, in vivo , the mechanisms underlying the development of cardiovascular function in the horse fetus, with particular relevance to baroreflex function and hind limb vascular arterial reactivity to constrictor agonists. Under general anaesthesia, vascular catheters were inserted and a Transonic flow probe was implanted around one of the metatarsal arteries of 13 horse fetuses, either at 0.6 of gestation ( n = 6) or at 0.9 of gestation ( n = 7, term ∼335 days). At least 5 days after surgery, pressor, vasoconstrictor and cardiac chronotropic responses to exogenous bolus doses of phenylephrine, angiotensin II and arginine vasopressin were recorded. Fetal cardiac baroreflex slopes were obtained using the peak pressor and heart rate responses to increasing doses of phenylephrine. Fetal treatment with phenylephrine, angiotensin II and vasopressin produced significant changes in arterial blood pressure, hind limb vascular resistance and heart rate. Pressor and vasopressor responses to all agonists were greater at 0.9 than at 0.6 of gestation; however, fetal cardiac baroreflex sensitivity decreased with advancing gestational age. Correlation analysis revealed that fetal plasma cortisol rather than gestational age was a greater determinant of pressor and vasopressor reactivity. In contrast, gestational age rather than cortisol better determined heart rate and baroreflex responsiveness in the equine fetus. The data show that development of cardiovascular function in the equine fetus occurs via cortisol-dependent and -independent pathways.     

Target cell stimulation of dissociated serotonergic neurons in culture

Dissociated mesencephalic raphe cells from fetal rats (14-18 days) were grown in culture in 96 well Linbro plates. The maturation of serotonergic cells was qualitatively studied using immunocytochemistry with a serotonin antibody and quantitatively by measuring the retention of radioactivity following incubation in the presence of a low concentration of [3H]5-hydroxytryptamine (6 X 10(-8) M). The 5-hydroxytryptamine immunoreactive neurons showed specific staining in the perikaryon, nucleus, dendrites, axons and growth cones. These neurons formed varicose fibers and growth cones after 18 h in culture and survived for up to 21 days in culture. Each serotonergic neuron concentrated approximately 1 fmol of serotonin after 20 min of incubation. Maturation of mesencephalic serotonergic neurons was increased in co-cultures of both normal (hippocampus, cerebral cortex, olfactory bulb and striatum) and abnormal (spinal cord) target neurons. The best stimulation was produced by dissociated hippocampal neurons (14-18 days of gestation) on mesencephalic raphe cells (14 days of gestation) after 4 days in culture. This stimulation was seen in culture conditions which favored neuronal but not glial survival. Our results obtained using cultures of dissociated serotonergic cells are consistent with an expansive network pattern developed by this chemical transmitter system in the adult brain.     

Progress in the development of shrimp cell cultures in Thailand

Primary shrimp cell cultures were developed from lymphoid organ and ovaries of black tiger shrimp, Penaeus monodon, in double-strength Leibovitz's L-15 medium supplemented with 15% fetal bovine serum, 1% glucose, 5 g/L NaCl, 15% shrimp meat extract. The optimum conditions for primary culture in vitro were obtained in L-15 medium with an osmolality of approximately 730 ± 10 mmol/kg, a temperature range of 25--28 °C and incubation in a normal atmosphere. However, basal medium supplemented with 0.01% cholesterol could enhance good growth and cells performance initiated from lymphoid organ. Both epithelial-like and fibroblastic-like cells were observed from those organs within 2 days incubation. Within 3 days, 80% confluent monolayers were obtained from the lymphoid organ while cultures from other tissues required 5 days. Cultures were maintained for at least 43 days. Only cells from lymphoid organ could be subcultured and confluent monolayers achieved within 10 days post-spilt. Healthy cultures of the lymphoid cells did not persist beyond the third passage. Application of these primary shrimp cell cultures for studying pathogenic viruses of shrimp in vitro will be discussed.     

Involvement of dopamine receptors in experimental ulceration

The purpose of this study was to characterize dopamine binding sites in gastric (mucosa and muscle) tissue and to examine changes of gastric dopamine receptors in response to variable periods of cold-restraint stress (CRS). Scatchard analysis of binding data in tissues of non-stressed animals revealed a single, homogeneous class of saturable high-affinity dopamine binding sites in gastric mucosa (Bmax = 21.3 pmol/mg protein; KD = 4 X 10(-7) M) and in gastric muscle (Bmax = 34 pmol/mg protein; KD = 0.6 X 10(-7) M). After 1 h of CRS, a time at which a low (30%) incidence of gastric ulcers was observed, the binding in mucosa had increased by 53%. Scatchard analysis revealed a significant increase in dopamine receptor number (Bmax = 37.6 +/- 7.0 versus 21.3 +/- 2.0 pmol/mg protein) and no significant change in affinity (KD = 6.8 +/- 1.6 versus 4 +/- 0.7 X 10(-7) M). No change in 3H-dopamine binding to muscle tissue was observed. These results indicate that up-regulation of mucosal dopamine receptors may precede the development of gastric ulcers.     

Effect of feeding on the diurnal rhythm of plasma cortisol and adrenocorticotrophic hormone concentrations in the pregnant ewe and sheep fetus.

The effects of two different feeding regimes on the 24 h profiles of maternal and fetal plasma cortisol and adrenocorticotrophic hormone (ACTH) concentrations were studied in eight pregnant ewes between 123 and 144 days of gestation. Once daily-fed ewes (n = 4) received 1 kg of lucerne-chaff at 11.00 h, and multi-fed ewes (n = 4) received 100-200 g of lucerne-chaff at 09.00, 11.00 and 13.00 h and then 150 g until 09.00 h the following day. There were significant differences between the two feeding groups in the 24 h profile of maternal plasma osmolality; once daily feeding at 11.00 h was associated with a peak in maternal plasma osmolality at 15.00 h whereas maternal plasma osmolality reached plateau levels at around 17.00 h in the multi-fed group. There were also differences between the two feeding groups in the 24 h profiles of maternal and fetal plasma glucose. Maternal and fetal plasma glucose reached peak concentrations at 19.00 h in the once daily-fed ewes in contrast to the multi-fed group, where a plateau in maternal and fetal plasma glucose was reached between 19.00 h and 09.00 h the following day. A significant diurnal variation in the plasma concentrations of cortisol was present in the once daily-fed ewes from 123 days gestation and in their fetuses after, but not before, 135 days gestation. Plasma cortisol peaked at 11.00 h in the ewes and at 13.00 h in the fetuses of this group. In the once daily-fed group there was also a significant diurnal variation in maternal and fetal plasma ACTH; plasma ACTH concentrations were highest at 11.00 h in the ewes aged between 123 and 144 days and in fetuses after 135 days gestation. In the multi-fed group, whilst ACTH was highest at 09.00 h in the ewes and at 13.00 h in the fetuses, there was no significant diurnal variation in the plasma concentrations of cortisol in the ewes or fetuses of this group at any stage between 123 and 144 days gestation.     

Comparative production of interferon by human fetal, neonatal, and maternal cells

Production of interferon was studied in fibroblasts cultured from human fetal, neonatal, and maternal tissue. Human fetal and maternal cells were paired to diminish genetic variability. Fetal cells displayed an increased response to two inducers of interferon, virus and synthetic double-stranded ribopolynucleotide. Fetal cells released 300-fold more interferon than maternal cells on exposure to poly rI:rC. This enhanced capacity for interferon production was consistent in cultures developed from fetal skin obtained between the 10th and 20th gestational week. The response was relatively stable, persisting in cells cultured for 18 generations (about 14 weeks). On infection with Newcastle disease virus, fetal cells produced, on the average, 4 to 6.5 times more interferon than maternal or neonatal cells. The virus was adsorbed with equal efficiency by each type of cell. Increased production is apparently independent of the rates of overall protein synthesis, since fetal and maternal cells have very similar rates of total protein synthesis.