bluuebunny/crossref_metadata_2025 huggingface dataset:
Decidua and placenta in mice after treatment with a synthetic glucocorticoid
Authors: Matejevic D , Heilmann P , Schuster C , Schoneshofer M , Graf R
Published: October 2005

To investigate a possible long-term effect of glucocorticoids on decidua and placenta of mice, a single dose of 24 mg kg-1 body weight triamcinolone acetonide in crystalline suspension was given subcutaneously to NMRI mice on gestational day (GD) 2. Deciduae and placentae, as well as corticosterone and triamcinolone concentrations in maternal plasma of GDs 10 and 17 were examined. NADPH-cytochrome P450 reductase involved in drug biotransformation was detected immunocytochemically and showed co-localization with NADPH diaphorase histochemistry in the decidua and placenta. Both reactions were higher in endothelial cells of decidual sinusoids on GD 10, but were lower on GD 17 in the trophoblast, spongiotrophoblast and extraplacental visceral yolk-sac epithelial cells of treated mice than in untreated animals. Histochemistry of 11 beta-hydroxysteroid dehydrogenase, an enzyme that metabolizes biologically active adrenocortical steroids and their synthetic congeners in the placenta, showed higher activity on GD 17 in enlarged labyrinthic trophoblast I cells of treated mice than in untreated animals. As corticosterone concentrations were still decreased on GD 17, when triamcinolone concentrations were no longer detectable, a long-term suppression of adrenal gland function seems obvious.
Vascular responses to sodium nitroprusside in the human fetal-placental circulation
Authors: Read MA , Giles WB , Leitch IM , Boura AL , Walters WA
Published: October 2005

This study examined the activity of sodium nitroprusside (SNP) in the human fetal-placental circulation in vitro in pathological and experimental conditions in which vascular function may be impaired. SNP (13-3400 nM) caused a concentration-dependent reduction in fetal arterial perfusion pressure (FAP) in Krebs' perfused placental cotyledons, at basal tone and following pre-constriction with prostaglandin F2 alpha (PGF2 alpha). SNP-induced reduction in FAP in the PGF2 alpha pre-constricted fetal-placental circulation was enhanced approximately six-fold (5.85) in those placentae pre-treated with the nitric oxide (NO) synthase inhibitor N omega-nitro-L-arginine (100 microM). Reductions in FAP in the preconstricted fetal-placental vasculature caused by SNP were not altered by prior infusion of ouabain (100 nM) into the fetal circulation or during low oxygen perfusion (O2 tension < 50 mmHg). No differences were observed in the responses obtained to SNP in placentae obtained from women with normotensive pregnancies or those associated with (i) pregnancy-induced hypertension, (ii) intra-uterine growth retardation, or (iii) an elevated umbilical-artery Doppler-ultrasound systolic/diastolic ratio, in either preconstricted placentae or those at basal tone. These findings are consistent with an up-regulation of guanylate cyclase/cGMP-mediated vasodilatation in the fetal-placental vasculature following complete blockade of endogenous NO production.
Amniotic fluid composition and fetal and placental growth rates in genetically hypertensive and normotensive rats
Authors: Erkadius E , Morgan TO , Di Nicolantonio R
Published: October 2005

Reduced birth weight has been observed in offspring of the spontaneously hypertensive rat (SHR) and in human hypertension. To determine which uterine factors might contribute to this fetal underdevelopment, fetal and placental growth rates and the volume and composition of amniotic fluid were measured in SHR and normotensive control Wistar Kyoto (WKY) rats during the final trimester of intra-uterine development. SHR and WKY fetuses were collected on Days 15-22 of pregnancy, and fetal and placental weight and amniotic fluid volume were recorded. The sodium and potassium concentrations of amniotic fluid were also measured. Placental weight was significantly lower in SHR than in WKY between Days 15 and 20 of gestation, but significantly higher on Days 21 and 22. Fetal weight was significantly lower in SHR between Days 17 and 22. These differences were reduced or abolished when fetal and placental weights were corrected for differences in maternal weight between strains. Amniotic fluid volume was significantly lower in SHR between Days 15 and 18, but significantly higher at Days 20, 21 and 22. Amniotic fluid sodium concentration was relatively constant over the period of observation and not different between strains. SHR amniotic fluid potassium concentration was significantly lower than that of WKY near term. Thus, the altered fetal and placental weight of SHR may be due to the overall reduced growth rate of this strain. However, the rate of fluid and electrolyte resorption close to term is markedly different between strains. The mechanism for this altered fluid and electrolyte handling by the SHR feto-placental unit remains to be determined.
Relationship between lupus anticoagulant (LAC) and pregnancy-induced hypertension
Authors: Matsumoto T , Sagawa N , Ihara Y , Kobayashi F , Itoh H , Mori T
Published: October 2005

Lupus anticoagulant (LAC), a serum antiphospholipid autoantibody, is believed to be one of the causes of infertility or fetal loss. The purpose of the present study was to evaluate the role of LAC in the pathogenesis of hypertension during pregnancy. In this study, 20 pregnant women with hypertension were classified into two groups: 14 patients who did not have hypertension before the pregnancy but developed it during the pregnancy (pregnancy-induced hypertension; Group A) and 6 patients who had hypertensive or renal disease before the pregnancy, and developed further hypertension during the pregnancy (pregnancy-aggravated hypertension; Group B). A LAC coagulation assay was performed, and the presence of LAC in each group was compared. All 14 patients in group A were LAC-negative. In contrast, 3 of the 6 patients in group B were LAC-positive, and had clinical autoimmune diseases. The incidence of pregnancy-induced hypertension was also examined in 15 pregnancies from 9 LAC-positive women who had a history of repeated fetal loss but no systemic autoimmune disease (Group C). None of these 15 pregnancies had hypertensive complications, even when they reached term. In the placentas of LAC-positive women, no characteristic changes other than fibrinoid degeneration and microscopic infarction were observed upon histological examination. These results suggest that LAC does not relate with the onset of hypertension during pregnancy.
Expression pattern of cytokines in the different compartments of the feto-maternal unit under various conditions
Authors: Stallmach T , Hebisch G , Joller H , Kolditz P , Engelmann M
Published: October 2005

Concentrations of five cytokines, GM-CSF, G-CSF, IL-1, IL-6 and IL-8, were determined within five compartments under four different conditions: at the time of a Caesarean section performed between 25 and 38 weeks' gestational age in normal pregnancy without uterine contraction (n = 12), in normal pregnancy with labour already established (n = 8), in pregnancy complicated by amniotic infection (n = 11), or under the conditions of preeclampsia with fetal intrauterine dystrophy (n = 13), cytokine concentrations were determined in fetal arterial and venous blood, in amniotic fluid, and in retroplacentally obtained maternal blood and peripheral maternal blood. With dystrophy, the concentrations of GM-CSF, G-CSF and IL-1 were about 20-50% lower (P < 0.01) in the amniotic fluid, and IL-6 and IL-8 were elevated in maternal peripheral blood (P < 0.01) but not within maternal retroplacental blood. Thus, preeclampsia/intrauterine dystrophy is characterized by reduction of some cytokines within the amniotic fluid compartment and concomitant reactive augmentations of other cytokines within the maternal and fetal organism. With amniotic fluid infection, concentrations of G-CSF, IL-6 and IL-8 were elevated in all compartments (P < 0.001) but GM-CSF and IL-1 showed a significant rise only within amniotic fluid and retroplacental maternal blood (P < 0.001), a rise that was apparently not transmitted to peripheral maternal or fetal blood. Care was taken to exclude the presence of uterine contractions in the group of controls, because this condition by itself causes severe elevation of cytokine concentrations, which are pronounced within amniotic fluid.
Endothelin receptors in the human amnion, chorion laeve, decidua vera and placenta
Authors: Hasegawa M , Sagawa N , Itoh H , Inamori K , Mori T , Yano J , Ogawa Y , Yoshimasa T , Nakao K
Published: October 2005

The levels of endothelin-1 (ET-1) and the characteristics of endothelin (ET) receptors were investigated in the amnion, chorion laeve, decidua vera and placenta by using a specific radioimmunoassay for ET-1 and a saturation binding assay for ET. ET receptor gene expression in these tissues was also examined by Northern blot analysis. The levels of ET-1-like immunoreactivity (ET-1-LI) in the human amnion, chorion laeve, decidua vera and placenta obtained at elective Caesarean section before labour onset at term (mean +/- s.e.m.) were 1260 +/- 380 (n = 6), 3740 +/- 980 (n = 4), 4550 +/- 780 (n = 4) and 2450 +/- 470 (n = 4) pg g-1 wet weight, respectively. The levels of ET-1-LI in the tissues obtained after spontaneous vaginal deliveries at term did not differ from these. Gel-permeation chromatography and reverse-phase high-performance liquid chromatography revealed that the ET-1-LI in these tissues was mainly composed of ET-1. Scatchard analysis of the saturation binding assay for [125I]-labelled ET-1 and [125I]-labelled ET-3 indicated that high concentrations of both ET-A and ET-B subtypes of receptor were present in membrane fractions from the chorion laeve, decidua vera and placenta. However, in membrane fractions from the amnion, no ET receptors could be detected. These results were confirmed by Northern blot analysis using human ET-A and ET-B receptor cDNA probes. Taken together, these results suggest that the amnion is not the site of action of amniotic ET, and that ET may be involved in the regulation of functions of the chorion laeve or decidua vera.
Effect of maternal glucocorticoid treatment on ovine fetal fluids at 0.6 gestation
Authors: Tangalakis K , Moritz K , Shandley L , Wintour EM
Published: October 2005

This study examined the effects of maternal dexamethasone treatment on the volume and composition of fetal fluids, and on placental morphology at 0.6 gestation (80-90 days). Nine pregnant ewes were infused with dexamethasone (D, 0.76 mg h-1 for 72 h) while an additional nine ewes received saline (S, 0.38 mL h-1 for 72 h). Allantoic fluid (ALF) volume was significantly greater (P < 0.01) in the D group (737 +/- 116 mL) than in the S group (190 +/- 55 mL), but there was no difference in amniotic fluid (AMF) volume. The urine flow rate was 11 times higher in three D fetuses. The 51Cr-EDTA infused into the bladders of four fetuses during the final 4-5 h of the 72 infusions was detected in both AMF and ALF. Dexamethasone treatment significantly altered the composition of the fetal fluids but had no affect on fetal body weight, organ weights and placental weight; however, there were fewer cotyledons under 5 g (P < 0.05). In the D group, 3% of cotyledons were of the 'bovine' type in morphology, whereas all cotyledons in the S group were of the 'ovine' type. These findings suggest that prolonged exposure to large doses of glucocorticoids during pregnancy would affect the volume and composition of the fetal fluids and placental morphology, with potentially detrimental effects on the fetus.
Regulation of fetal breathing
Authors: Rigatto H
Published: October 2005

Traditionally, the idea of transient asphyxia plus some degree of cold stimulation has been used to explain the establishment of continuous breathing at birth. This idea was nurtured by observations made in the acute fetal preparation at a time when fetal breathing was considered absent. Experimental observations made in the past two decades have challenged this traditional view. First, complete peripheral chemodenervation, essential to the hypoxic stimulus theory, did not affect fetal breathing or the establishment of continuous breathing at birth. Second, occlusion of the umbilical cord in utero, as long as some oxygenation is provided to the fetus in order to avoid fetal hypoxaemia, establishes continuous breathing in utero, in the absence of all sensorial input thought to be important for the establishment of continuous breathing. These observations led us to hypothesize the presence of a placental factor responsible for the inhibition of breathing in utero. This placental factor appears to be a peptide with a molecular mass between 3.5 and 10 kDa. This review will also explore some new observations regarding the generation of central respiratory activity in the fetus, and suggests that the rhythm generator is a neuronal network in which the unit is a pacemaker-like cell uniquely responsive to CO2.
Development of the newborn GI tract and its relation to colostrum/milk intake: a review
Authors: Xu RJ
Published: October 2005

During the immediate postnatal period, the gastrointestinal (GI) tract undergoes profound growth, morphological changes and functional maturation. The oesophagus shows an accelerated cell proliferation in the epithelium and an increased production and accumulation of mucus in the glands. The stomach shows a rapid tissue growth and a marked increase in acid secretion capacity. The intestine shows increased tissue growth and marked epithelial modifications; the latter include the loss of the ability by the epithelial cells of the small intestine to absorb macromolecules, and the loss of the ability by the epithelial cells of the large intestine to synthesize digestive enzymes and to absorb amino acids and glucose. These changes are apparently related to the onset of colostrum ingestion, because starved or water-fed newborns showed little changes in the GI tract. A number of hormones and growth-promoting peptides, such as insulin, cortisol, epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I), have been found at high concentrations in the maternal colostrum. There is evidence that colostrum-bone EGF and IGF-I play a role in postnatal GI development in newborns. The role of other colostrum-borne hormones and growth-promoting peptides remains to be assessed. Further studies are also required to demonstrate if colostrum-borne EGF and IGF-I can be used therapeutically to those newborns with immature or diseased GI tract, such as in cases of premature birth or prenatal growth retardation or cases requiring total parenteral nutrition.
Ventricular fibrillation in the neonate: elusive or illusive?
Authors: Kralios FA , Kralios AC
Published: October 2005

Ventricular fibrillation (VF) in mature large mammals is usually a terminal event. It constitutes the most common mode of exitus and the main cause of sudden cardiac death in humans. In neonates, VF is of particular interest because it often reverse spontaneously and promptly to potentially become a non-lethal event. Accordingly, the study of VF and spontaneous defibrillation (SDF) in the neonate is key for the understanding of the developmental anatomical and functional characteristics enabling mammalian myocardium to initiate and sustain this lethal arrhythmia. Such characteristics may include age-related changes of myocardial tissue properties, mass and geometry, autonomic cardiac innervation and myocardial perfusion/hydration. In the human neonate, VF/SDF could provide a plausible framework for explaining and directing the search for the elusive evidence underlying the mechanism and age distribution of the sudden infant death syndrome.
Immunocytochemical localization of renin in the developing ovine fetus
Authors: Rawashdeh NM , Rose JC , Rogers MS , Giammattei C , Iskandar SS
Published: October 2005

The ontogeny of renin distribution in the outer cortical segments was studied by immunocytochemistry in two groups of ovine fetal kidneys; one set of fetal kidneys was obtained at 104-106 days (0.73 gestation, n = 6), and the other at 138-140 days (0.96 gestation, n = 6). Similar studies were performed in kidneys obtained from a lamb (2 weeks old) and from non-pregnant adult sheep, n = 4. Using rabbit anti-mouse renin antiserum that was proven to cross react with sheep renin and 0.033% 3',3'-diamino benzidine tetrachloride as a chromogen, immunoreactivity was found to be localized in the classical juxtaglomerular apparatus and the afferent arteriole in the immature fetuses, newborn lamb and adult sheep. In the mature fetuses a more extensive distribution was noted. Immunoreactivity was found in the afferent arteriole and the juxtaglomerular apparatus as well as other segments of the arterial vascular tree. These findings suggest that renal renin distribution in the lamb fetus is developmentally regulated. The results also correlate well with reports about renal cortical renin content and plasma renin activity at the stages studied. These observations further support the hypothesis that increased renal renin expression occurs in the fetus just prior to birth.
Effects of corticotrophin-releasing factor and vasopressin on plasma adrenocorticotrophin molecular forms, aldosterone and corticosterone in young and adult rats and rabbits
Authors: Pradier P , Dalle M
Published: October 2005

Synthetic ovine corticotrophin-releasing factor (CRF) and arginine vasopressin (AVP) were injected alone or in combination (for each peptide 1 microgram/kg body weight) in 7-day-old and adult rats and rabbits. Fifteen minutes after the interscapulary injection, blood was collected for plasma adrenocorticotrophin (ACTH), corticosterone and aldosterone evaluation by RIA. The different circulating forms of ACTH were isolated by Sephadex G50 column chromatography with 1% formic acid and measured by RIA using 1-24 ACTH as standard. Such experiments were previously described in lambs and guinea-pigs using the same schedule. In young and adult rabbits the predominant circulating IR-ACTH form was 'big' ACTH; after stimulation with CRF, AVP or CRF + AVP the 'intermediate' IR-ACTH was greatly increased in adults, but no change was observed in young rabbits. In young and adult rats the predominant circulating form was 'intermediate' ACTH in control and injected animals; ACTH increased after CRF alone or in combination with AVP, but not after AVP alone. In both species the 'intermediate' forms of IR-ACTH were not eluted at the same time by chromatography, and calculated molecular weights were different: 14500 in rats and 9500 in rabbits. Plasma corticosterone and aldosterone were increased in rat and rabbit adults after CRF and AVP; however, they remained unchanged in young rabbits and slightly increased only after CRF in young rats in which corticosterone remained at a very low concentration compared with that in adults. Hence, the pituitary-adrenal axis of 7-day-old rabbits and rats in less reactive than that of sheep and guinea-pig of the same age.
Developmental changes in beta-adrenergic and muscarinic modulations of Ca2+ currents in fetal and neonatal ventricular cardiomyocytes of the rat
Authors: Masuda H , Sumii K , Sperelakis N
Published: October 2005

Developmental changes of the beta-adrenergic and muscarinic modulations acting on the slow Ca2+ channels in rat ventricular cardiomyocytes were investigated using Ba2+ as the charge carrier (IBa(L)). Single cardiomyocytes from fetal and neonatal rats were freshly isolated, and currents were recorded by whole-cell voltage clamp in Na(+)-free, K(+)-free external solution. Basal current densities showed a large increase between fetal days 15 and 18, and a small decrease after fetal day 20. The ability of isoproterenol (ISO, 1 microM) to enhance IBa(L) increased dramatically between fetal days 18 and 20, and remained almost constant thereafter during the neonatal period. The ability of forskolin (FOR, 10 microM) to stimulate IBa(L) also increased markedly between fetal day 18 and neonatal day 1. Carbachol (CCh), in a dose-dependent manner, reversed the stimulation of the IBa(L) produced by ISO in neonatal cardiomyocytes. The IC50 values for CCh inhibition of IBa(L) was almost the same on all neonatal days tested (neonatal days 1, 5 and 10). The results indicate that there are developmental changes in beta-adrenergic modulation of IBa(L) in the late fetal period, including a large jump in sensitivity to ISO on about fetal day 19. These findings are consistent with the steep increase in number of beta-adrenergic receptors that occurs between fetal days 18 and 20 (Kojima, Sperelakis & Sada, 1990a: Kojima, Ishima, Taniguchi, Kimura, Sada & Sperelakis, 1990C).
Effect of thyroid status in the perinatal period on oxidative capacities and mitochondrial respiration in porcine liver and skeletal muscle
Authors: Herpin P , Berthon D , Duchamp C , Dauncey MJ , Le Dividich J
Published: October 2005

Regulatory thermogenesis is reduced in newborn piglets which have been made hypothyroid during late gestation by giving the sow a high glucosinolate rapeseed diet (test animals). Thereafter, the progressive increase in thermogenic capacity parallels the development of a marked postnatal hyperthyroid state. To explain these effects of thyroid hormones at the tissue and mitochondrial levels, we have examined both liver and skeletal muscle to determine possible underlying changes in (i) tissue oxidative capacities (cytochrome oxidase (CO) activity), between 80 d of gestation and 48 h after birth, and (ii) mitochondrial content and respiratory capacities at 24 h of life. In control piglets, CO activity increased sharply during late gestation and the first 2 d of life in liver and rhomboideus (RH) muscle (P < 0.01), whereas only a prenatal increase was observed in longissimus dorsi (LD) muscle. Test fetuses were hypothyroid and had lower CO activities than controls during late gestation in RH muscle (P < 0.06, at 110 d of gestation; P < 0.08, at birth) and in liver (P < 0.001, at birth). The postnatal increase in CO activity in RH muscle and liver was higher (P < 0.05) in test than in control piglets, and as a result the difference between the 2 groups was not significant by 24-48 h of life. There was no effect of treatment on LD muscle. At 24 h, hyperthyroid test piglets had lower amounts of mitochondrial proteins than controls (P < 0.05) in all three tissues, possibly reflecting reduced mitochondrial protein synthesis during fetal life and suggesting that high postnatal T3 levels did not bring about major increases in protein synthesis within 24 h. However, test piglets exhibited higher rates of mitochondrial respiration than controls in liver and RH muscle, as shown by increases in State III and FCCP-stimulated respirations (P < 0.05), and mitochondrial CO and creatine kinase activities (P < 0.05). In RH muscle, both subsarcolemmal and intermyofibrillar mitochondria showed the same trends. No changes were observed in LD muscle. Our results describe for the first time the effect of thyroid hormones on perinatal oxidative capacities and neonatal mitochondrial respiration in liver and skeletal muscle of the pig, through both the short-term regulation of mitochondrial respiration and the long-term control of mitochondrial biogenesis. The differential sensitivity of LD and RH muscles to thyroid hormones is discussed.
Prediction of cerebral blood flow in fetal lambs by carotid artery ultrasonic flow transducer
Authors: Covert RF , Schreiber MD , Torgerson LJ , Torgerson RW , Miletich DJ
Published: October 2005

To determine whether common carotid artery blood flow measured with an ultrasonic flow transducer would predict brain blood flow in fetal sheep, we measured unilateral common carotid artery blood flow and compared this to simultaneous measurements of total brain blood flows made by radioisotope-labelled microsphere techniques. We studied anaesthetized, exteriorized fetal sheep with intact umbilical circulation after ligation of extracranial, extracerebral arteries and placement of a common carotid artery flow transducer; five fetuses at 120 d gestation had 19 total comparison measurements. As measured by microsphere technique, mean basal blood flow during undisturbed conditions to regional brain areas were similar to normal values reported for the exteriorized ovine fetus; these flows were highly correlated to fetal PaCO2 and successfully varied over a wide range (total brain 9.1-200.4 ml/min/100g and total cortex 6.1-153.1 ml/min/100g) in subsequent experimental conditions of hypercapnia or occluded blood flow. Blood flow as measured by flow transducer significantly correlated (P < or = 0.01) with microsphere measurements of blood flow to total brain (r = 0.56) and total cortex (r = 0.62); regional flow to cerebellum (r = 0.70) and thalamus (r = 0.60) also correlated to transducer measurements. Stronger correlations were observed at low-flow conditions to total brain (r = 0.83) and to total cortex (r = 0.90). As measured by microsphere technique, right and left cortical blood flows were highly correlated (P = 0.0001, r = 0.97), indicating that the flow transducer or surgical manipulation did not disturb the distribution of cerebral blood flow. The mean values for zero flow reference of the transducer were < 1.5% of mean basal flow values. It is concluded that the common carotid artery flow transducer technique developed in this study provides an accurate prediction of blood flow to total brain and total cortex over a wide range of values in fetal sheep. This technique provides a methodologic advantage to sequential experimental interventions and may prove advantageous to studies of fetal sheep cerebral circulation.
Control and management of ovarian follicles in cattle to optimize fertility
Authors: Thatcher WW , de la Sota RL , Schmitt EJ , Diaz TC , Badinga L , Simmen FA , Staples CR , Drost M
Published: October 2005

Experiments were designed to elucidate the control of ovarian follicle turnover and the impact of follicular dynamics on the subsequent fertility of dairy cattle. An experimental model was established to examine the interrelationships of gene expression for steroid enzymes, the insulin-like growth factor system and inhibin production as associated with follicle selection, dominance and atresia. Follicular dynamics during the postpartum period and the oestrous cycle are shown to be altered markedly by the metabolic demands of lactation. The feeding of ruminally-inert fat stimulated follicular development and improved reproductive performance. The development of persistent follicles during oestrus synchronization causes a reduction in fertility that can be corrected by recruitment and selection of a new ovulatory follicle after the injection of a gonadotrophin-releasing hormone agonist. Present systems of oestrus synchronization need to consider both synchronization of follicular development and corpus luteal regression in order to optimize fertility. With current systems manipulating follicle development, the potential to implement a timed insemination programme to improve reproductive management exists. Ovulation of the first-wave dominant follicle with human chorionic gonadotrophin provides a means to markedly enhance concentrations of plasma progesterone in the luteal phase.
Production of extracellular matrix, fibronectin and steroidogenic enzymes, and growth of bovine granulosa cells in anchorage-independent culture
Authors: Rodgers RJ , Vella CA , Rodgers HF , Scott K , Lavranos TC
Published: October 2005

A proportion of the granulosa cells from bovine antral follicles will survive, like stem cells, in anchorage-independent culture. To study these cells, bovine granulosa cells were isolated from medium-sized follicles (3-5 mm), plated out (in aliquots of 2.5 x 10(4) viable cells) onto a 1 mL agar base, and overlaid with 1 mL of methycellulose solution in culture medium (control). The cells were cultured (14 days) and then processed for histology (n = 14) or Western immunoblotting (n = 5). Under control conditions or after treatment with basic fibroblast growth factor (bFGF; 50 ng mL-1), a proportion of the granulosa cells divided to produce colonies; individual cells remained small. bFGF increased the number of cells harvested (15.8 +/- 7.3-fold, as measured indirectly by the relative amount of the nuclear La antigen), increased the average diameter of the colonies from 88.9 +/- 13.5 microns to 136.5 +/- 4.9 microns and stimulated the production of fibronectin 5.7 +/- 1.5-fold (P < 0.05). An extracellular matrix, which has previously been shown to be a basal lamina, was observed in 19.1% of the colonies (total of 350 colonies examined; n = 8 experiments). Cells treated with dibutyryl cAMP (1 mM) hypertrophied and had 50 +/- 28.7-fold and 102.6 +/- 55.8-fold higher levels of cholesterol side-chain cleavage cytochrome P450 (P < 0.001) and 3 beta-hydroxysteroid dehydrogenase (P < 0.01) respectively (n = 5). Thus, granulosa cells with characteristics of stem cells can divide and produce extracellular matrix, or be induced to differentiate when in culture without anchorage.
Metacarpal growth and systemic markers of bone metabolism in the ovine fetus
Authors: Collignon H , Davicco MJ , Barlet JP
Published: October 2005

Bone metabolism was assessed in 56 Ile de Francex(RomanovxLimousine) fetal lambs killed between Day 80 and Day 145 of gestation. In each fetus, the length, width and weight, as well as the calcium and phosphorus content of the left diaphyseal metacarpal bone were measured. Plasma alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) activities, bone ALP (B-ALP), osteocalcin (OC) and insulin-like growth factor-I (IGF-I) were assayed in these fetuses and in six newborn lambs from birth until one month after birth. Fetal growth is characterized by an increase in bodyweight, bone size and bone mineral content from Day 80 to Day 132 of gestation. These parameters did not significantly vary until birth. Plasma concentrations of IGF-1, OC and B-ALP increased from Day 80 to Day 132. Between Day 132 and birth, plasma IGF-I and B-ALP concentrations did not significantly vary, whereas plasma OC concentration decreased, confirming the usefulness of OC as a marker of osteoblastic activity and bone formation in the ovine species. The increase in plasma IGF-I, B-ALP and OC concentrations observed during the first two weeks of postnatal life indicate an intense skeletal growth in these animals, which was confirmed by the bodyweight growth curve.
Relation between cerebral oxygen delivery and neuronal cell damage in fetal sheep near term
Authors: Berger R , Lehmann T , Karcher J , Schachenmayr W , Jensen A
Published: October 2005

Asphyxia is one of the major causes for fetal brain damage. Although the quality of life of the so affected children is mostly very limited, the pathogenesis of hypoxic fetal brain damage is poorly understood. Particularly, there is a lack of studies, in which cerebral oxygen delivery is directly correlated to the extent of neuronal cell damage in the same brain specimens. Therefore, we measured cerebral oxygen delivery before (- 1 h), during (+3 min & +27 min) and after (+10 min, +4 h, +72 h) 30 min of ischaemia in 5 chronically catheterized normoxemic fetal sheep at 129 +/- 1 days gestation (term is at 147 days) using the microsphere method. In contrast to previous studies (Williams et al. 1990), we arrested carotid arterial blood flow above the lingual artery for 30 min during surgery. Seventy-two hours later the fetal brains were fixed in vivo under barbiturate anaesthesia of both the fetus and the ewe. After cerebral blood flow analysis neuronal cell damage was assessed with light microscopy in 43 specimens of the fetal brain after cresyl violet/fuchsin staining using a scoring system. After arrest of carotid arterial blood flow cerebral blood flow was reduced by 80%. Neuronal cell damage was focussed on the cerebral cortex. Almost no damage could be detected in deeper parts of the brain. In the cerebrum there was threshold oxygen delivery of 3 ml O2/100 g tissue/min, below which neuronal damage occurred. However, there was no correlation between cerebral oxygen delivery and neuronal cell damage in specimens of the cerebrum, in which oxygen delivery was less than 3 ml O2/100 g tissue/min, suggesting selective vulnerability. Therefore, in addition to the reduction in cerebral oxygen delivery, other variables, e.g. neurotransmitter release, receptor pattern or oxygen radicals, may be involved in the development of brain damage.
Effects of lung expansion on lung liquid production in vitro by lungs from fetal guinea-pigs. II. Evidence for generation of an inhibitory factor
Authors: Nelson PG , Perks AM
Published: October 2005

Lungs from near-term fetal guinea-pigs were supported in vitro for 3 h; lung liquid production was measured by a dye-dilution method using Blue Dextran 2000 [fetuses 63 +/- 2 days of gestation, 97.6 +/- 19.8 (SD) g body weight]. Preparations were incubated in pairs taken from the same mother. Twenty lungs incubated in pairs without treatment (controls) showed no significant changes in fluid production throughout incubation (analysis of variance; regression analysis); rates in successive hours were: first lung, 1.36 +/- 0.39, 1.09 +/- 0.34 and 1.27 +/- 0.42 ml/kg body weight per h; second lung, 1.46 +/- 0.52, 1.09 +/- 0.41 and 1.18 +/- 0.43 ml/kg body weight per h. Twenty lungs were incubated similarly in pairs, but after one hour one lung from each pair was expanded with Krebs-Henseleit saline in volumes approximating those of the first breath (68 +/- 10% of lung volume). The expanded lungs began to reabsorb fluid immediately after expansion; the untreated lungs also stopped production or reached reabsorption by the final hour. Rates in successive hours were: expanded lungs; before expansion, 1.00 +/- 0.21, after expansion, -0.23 +/- 0.17 and 0.14 +/- 0.09 ml/kg body weight per h; unexpanded lungs, 1.27 +/- 0.49, 0.02 +/- 0.01 and -0.01 +/- 0.004 ml/kg body weight per h. The decrease in production was significant for each type of lung. The effects persisted in both expanded and unexpanded lungs in the presence of 1.78 x 10(-5) M phentolamine (n = 12; 70 +/- 2% expansion). The results suggest that expansion of the lungs at birth may release an unknown inhibitory factor, provisionally termed Expansion Factor (EF), within the lungs; this agent, probably not a catecholamine, can change lung fluid production into reabsorption and may partly account for the failure of beta-antagonists to prevent fluid reabsorption at delivery.
Arousal responses of the newborn piglet to airways obstruction and rebreathing during normothermia and hyperthermia
Authors: Galland BC , Wehner NS , Bolton DP , Taylor BJ
Published: October 2005

Most experimental studies of arousal to respiratory stressors have been performed under neutral thermal conditions. The present study focussed on arousal responses with the added challenge of heat stress. The subjects were two groups of 10 sedated piglets aged 4-6 days and 2-6 days respectively. Respiratory stimuli (partial and total airways obstruction (AO) or rebreathing (RB) expired gases) were applied during non-rapid-eye-movement (NREM) sleep. Measurements of heart rate, SaO2, intra-pleural pressure or inspired CO2 and O2 were recorded during tests in normothermia and hyperthermia. Hyperthermia significantly shortened the time to arousal. Thus, arousal times from partial and total AO and from RB were: in normothermia, 40.3 +/- 5.8, 9.2 +/- 0.7 and 94.9 +/- 14.7 s respectively; in hyperthermia, 17.8 +/- 3.7, 7.6 +/- 0.9 and 68.5 +/- 9.1 s respectively. Cardio-respiratory variables at arousal were similar in both thermal states. Seven non-sedated piglets were challenged with RB stimuli during normothermia only to determine the influence of sleep state on arousal. Arousal in REM sleep was delayed approximately 2-3-fold (NREM, 41.2 +/- 8.2 s; REM, 88.5 +/- 18.1 s), occurring at a lower SaO2 and higher inspired CO2. It is concluded that arousal from NREM sleep under adverse conditions of hyperthermia shortens the arousal time from asphyxial stimuli induced by AO and RB with no change in the arousal threshold.
Influence of hyperthyroidism induced at prepuberty on the epididymal lipids, number and motility of spermatozoa in rats
Authors: Kumar PN , Aruldhas MM , Juneja SC
Published: October 2005

Fifteen prepubertal rats were divided into 3 groups of 5 each: (1) hyperthyroid group (TH), the rats were treated with thyroxine (T4) (25 micrograms/100g body weight/day) for 60 days from the age of day 31 to day 90; (2) T4-withdrawal group (TH-T4), the rats were given T4 for 30 days from the age of day 31 to day 60 and then the T4 treatment was withdrawn for the following 30 days from the age of day 61 to day 90 and the animals were given vehicle during this period; and (3) control group, the rats were given vehicle for 60 days from the age of day 31 to day 90. All were killed at the age of day 91. Serum levels of testosterone, T4 and triiodothyronine increased in the TH group (P < 0.001). The levels decreased to the euthyroid status in the TH-T4 group. Hyperthyroidism caused various changes in the levels of epididymal lipids. The levels changed further or were restored differentially in the TH-T4 group. The number of spermatozoa decreased, in caput epididymis (CpE) as well as in cauda epididymis (CdE), in the TH group (P < 0.001). The number was not restored in the TH-T4 group. The forward motility of the spermatozoa, determined in CdE, decreased in the TH group (P < 0.001) and was not restored in the TH-T4 group. The study showed that chronic hyperthyroidism, induced at the prepubertal age, causes various changes in epididymal lipid composition and sperm parameters. The study may be helpful in revealing the reasons for male infertility in hyperthyroid patients.
Rat diaphragm during postnatal development. I. Changes in distribution of muscle fibre type and in oxidative potential
Authors: Fratacci MD , Levame M , Rauss A , Bousbaa H , Atlan G
Published: October 2005

The changes occurring in the histochemical characteristics of the rat diaphragm during the postnatal period were examined. Fibre-type distribution, fibre oxidative capacity, i.e. succinate-dehydrogenase (SDH) activity, and cross-sectional area were compared in the costal (COS) and crural (CRU) regions, and across their abdominal and thoracic surfaces. The proportions of type I and IIb fibres in both COS and CRU increased with age, while the proportion of type IIa fibres progressively decreased. For COS, fibre distribution was homogeneous over the entire muscle and did not change after 4 weeks. For CRU, it was heterogeneous with a higher proportion of type I fibres on the thoracic surface as from the first week. All fibre types significantly increased in cross-sectional area between 1 and 8 weeks, with no significant differences in COS and CRU. Mean SDH activity did not differ between COS and CRU or across the muscles. Mean SDH activities-were low and identical in all fibre types at birth, and then increased, peaking at the 6th week in type I and IIa fibres. When total muscle fibre oxidative capacity was calculated from an index including fibre-type proportion, cross-sectional area and mean SDH activity, it was significantly higher at 1 than at 8 weeks after birth; this might have functional implications for the newborn.
Effects of iron supplementation on iron uptake by differentiating cytotrophoblasts
Authors: Starreveld JS , van Denderen J , Kroos MJ , van Eijk HG , van Dijk JP
Published: October 2005

Cultured in Medium-199, cytotrophoblasts isolated from human placentae differentiate morphologically (e.g. syncytium formation) as well as biochemically (e.g. expression of transferrin receptors, TfRs) into syncytiotrophoblast-like structures. The highest TfR numbers are observed in cells cultured in iron-poor culture medium. Investigated were the implications of the variation in surface TfR numbers on the uptake of iron by cytotrophoblasts cultured in iron-poor Medium-199. Despite differences in TfR densities induced by culture time and iron availability, the initial rate of iron uptake did not change (80-100 pmol/mg protein/h). Homeostasis of iron uptake could be explained by adaptive changes in the rate constant for TfR endocytosis (kend), exocytosis (kexo) and TfR cycle times. In undifferentiated cells (cultured for 18 h) kend was 0.299 min-1. In differentiated cells (culture time 65 h, higher surface TfR densities), kend changed to 0.138 min-1. Culture for 65 h in diferric transferrin-enriched medium resulted in intermediate TfR densities together with an intermediate kend (0.210 min-1). Adaptive changes in the corresponding rate constant of exocytosis were less pronounced (0.192, 0.192 and 0.260 min-1 respectively). It is concluded that differentiating cytotrophoblasts regulate iron uptake by variation of both TfR numbers and the rate of receptor-mediated endocytosis and exocytosis.
Occurrence of a growth hormone-releasing hormone-like messenger ribonucleic acid and immunoreactive peptide in the sheep placenta
Authors: Lacroix MC , Jammes H , Kann G
Published: October 2005

Growth hormone releasing factor (GHRH) has been described in the rat, mouse and human placentae. This study reports the presence of an immunoreactive GHRH activity (IR-GHRH) in the ovine placenta. This activity was detected by radioimmunoassay from day 50 (D50) until the end of pregnancy. Higher IR-GHRH concentration in placental tissue was observed on days 100 (543 +/- 123 pg/g) and 140 (550 +/- 62 pg/g) and, when compared with the GHRH content of the ovine hypothalamus (1.2 ng/hypothalamus), represents a considerable amount of GHRH per placenta (a mean of 200 ng). Perifused placenta explants released IR-GHRH in vitro at a mean rate of 200 pg/g/h. Depolarization by 55 mM KCl increased the IR-GHRH concentration of the perifusion media 1.7 times over basal values. The elution position of GHRH immunoreactivity in the gel filtration chromatography profiles was the same for placenta and hypothalamus extracts and lay very near to the molecular weight of bovine GHRH. Northern blot hybridization analysis revealed the existence of a placental transcript whose size (0.75 kb) was comparable to the size of the ovine hypothalamus and rat placenta GHRH transcripts. Hybridization signal was observed at each stage studied from D50 until D120 of pregnancy. This study demonstrated the existence of a IR-GHRH peptide in the ovine placenta.
Culture of preantral ovarian follicles in the grey, short-tailed opossum, Monodelphis domestica
Authors: Butcher L , Ullmann SL
Published: October 2005

A culture system designed to support the development of individual preantral mouse ovarian follicles has been employed to study follicle growth in the New World marsupial species Monodelphis domestica. Preantral follicles were isolated mechanically and cultured individually in microdrops under oil. Preliminary results indicate that follicle growth was positively correlated to the concentration of follicle-stimulating hormone (FSH) provided, with 1.0-1.5 IU FSH mL-1 producing the best results. Incubation at the body temperature of M. domestica (33 degrees C) was found to be preferable to that at 37 degrees C. The culture system was able to support follicle growth; however, despite follicles exceeding the size when antrum formation occurs in vivo, they remained preantral.
A light microscopic study of oogenesis in the brushtail possum Trichosurus vulpecula
Authors: Frankenberg S , Newell G , Selwood L
Published: October 2005

Ovaries from young of the brushtail possum, Trichosurus vulpecula, were examined histologically and histochemically to determine stages of oogenesis. Groups of dividing oogonia were first present in a 13-day-old pouch young, with extensive oogonial proliferation after about 23 days of age. Meiosis was initiated in some oogonia by 48 days of age, and by 88 days numerous early primordial follicles were present. The first primary follicles had formed by 103 days of age. In oocytes of quiescent primordial follicles, dark granular material, which stained positively for protein, mainly occupied the perinuclear cytoplasm. Associated with the transition to primary follicles and continuing throughout oocyte growth was the production within the central cytoplasm of large clear vesicles and, to a lesser extent, lipid-like yolk bodies. The former were analogous to similar vesicles found in other species of marsupial, and have a putative role in development of the blastocyst. By contrast, yolk-like bodies are not found in all marsupial oocytes and their importance in development is unknown.
Regulation of the motility and metabolism of spermatozoa for storage in the epididymis of eutherian and marsupial mammals
Authors: Jones RC , Murdoch RN
Published: October 2005

The present review examines the mechanisms involved in sperm storage in the epididymis of therian mammals in terms of the supply of energy substrate and the regulation of motility and metabolism. Lipids, glucose, lactate and glycerol are possible metabolic substrates for sperm in the epididymis, but the role of these is uncertain and it may differ between marsupials and eutherians. Sperm are normally immotile in the epididymis, but ram and rabbit sperm may have an uncoordinated motility. Sperm metabolism is suppressed but is probably not strongly coupled to motility. Work on diluted sperm indicates that cyclic adenosine monophosphate, Ca2+, and pH play roles as intracellular messengers controlling the motility and metabolism of sperm, but no first messenger has been identified. A number of mechanisms of suppressing sperm motility and metabolism in the epididymis are considered, including a collective autoregulation, oxygen tension, osmotic pressure, viscosity and the extracellular concentration of H+, Ca2+, Na+, HCO3- and carnitine. However, there is no conclusive evidence for any of the mechanisms and there is clearly some variation between species in the mechanism of suppressing sperm activity. Sperm activation stimulates motility and a 4-5-fold increase in respiration rate that has not been reversed without compromising viability. Following activation, respiration supported by endogenous and/or exogenous substrates is much higher in marsupial than eutherian sperm, and marsupial sperm do not show a large stimulation of respiration on the addition of exogenous substrate, as is characteristic of most eutherian sperm.
Gamete biology of the new world marsupial, the grey short-tailed opossum, Monodelphis domestica
Authors: Moore HD
Published: October 2005

Mammalian gametes undergo a series of functional and developmental changes that culminate in fertilization. In order to appreciate the necessity for such complex processes as sperm maturation, capacitation and the intimate sperm-egg interactions leading to gamete fusion, it is important to understand how gametes may have evolved. In this respect, marsupials are particularly relevant since they exhibit features reminiscent of both non-mammalian vertebrates and eutherian mammals. The grey short-tailed opossum, Monodelphis domestica, is a New World marsupial from Brazil. It breeds well under laboratory conditions and is an excellent animal model to investigate marsupial gamete biology. As in other American marsupials, the spermatozoa of the opossum form pairs in the epididymis. Here, a number of studies carried out in this laboratory, related to sperm maturation, capacitation and fertilization in M. domestica, are reviewed and the gamete biology in this species is compared with what is known in other marsupials and eutherian mammals.