bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the mechanism of trypan blue teratogenicity in the rat developing in vivo and in vitro
Authors: Rogers John M. , Daston George P. , Ebron Marian T. , Carver Brenda , Stefanadis James G. , Grabowski Casimer T. 
Published: June 2005

AbstractTrypan blue is a potent teratogen in vivo and in vitro in the rat. Many of the abnormalities produced by trypan blue–including swollen neural tube and pericardium, subectodermal blisters, hematomas, and generalized edema–may result from altered fluid balance in and around the embryo. The present study demonstrates relationships between changes in the fluid environment around the embryo and appearance of anomalies. Rat embryos were exposed in utero or in vitro to trypan blue during the early period of organogenesis. Both exposures resulted in defects that are typical of trypan blue treatment. Osmolality of exocoelomic fluid (ECF) was measured on gestation day 10 in vivo and day 12 in vitro, both after 48 hr of exposure to trypan blue. In both cases ECF osmolality was significantly lower than controls. This was correlated with the presence of edema‐related anomalies in the embryo. On gestation day 11 in vivo, three days after maternal injection of trypan blue, ECF osmolalities were significantly higher than controls; however, there was tremendous variability in this parameter in day 11 treated embryos, and some had ECF osmolalities below the control range. Increased frequency of abnormalities was correlated with abnormal ECF osmolality, below and above the control range. Trypan blue probably exerts its teratogenic effects by disturbing the function of the visceral yolk sac. The movements of an amino acid and a monosaccharide across the visceral yolk sac were measured on gestation day 12 embryos in vitro. This aspect of yolk sac function was not altered by trypan blue exposure. Ultrastructure of the visceral yolk sac was observed after trypan blue exposure in vivo and in vitro. Endodermal cells in trypan blue‐treated yolk sacs contained fewer large, electron dense lysosomes than controls. These were replaced by numerous small vacuoles, which may contain trypan blue. Trypan blue causes osmotic changes in the rat embryo in vivo and in vitro. These changes are correlated with embryonic malformations. Alterations in yolk sac ultrastructure indicate that trypan blue affects the function of this membrane.
A postulated mechanism of β‐sympathomimetic induction of rib and limb anomalies in rat fetuses
Authors: Sterz H. , Sponer G. , Neubert P. , Hebold G. 
Published: June 2005

AbstractTreatment of gravid rats (days 6–15 of gestation) with the β‐sympathomimetic doxaminol resulted in wavy ribs and bent limbs in the offspring. The fetuses also exhibited defective mineralization. These anomalies were produced by pharmacologically effective doses of the drug. Prior treatment with the β‐receptor blocker carazolol prevented their formation, so that the β‐sympathomimetic action of doxaminol is evidently a causative factor. Various hypotensive agents whose activity is not mediated by β‐receptors failed to produce abnormalities. This eliminates the possibility of a non‐specific etiology such as diminished placental perfusion. The cyclooxygenase inhibitor indomethacin lowered the incidence of wavy ribs. Furosemide, a loop diuretic that stimulates renal prostaglandin synthesis, increased the incidence of abnormalities when combined with doxaminol. The nature of the anomalies found suggests that 1) fetal compression by the myometrium and 2) defective mineralization are prerequisites for their development. The first condition could be produced via the complex mechanism of β‐sympathomimetic‐induced stimulation of prostaglandin synthesis. Defective mineralization can result directly from cAMP‐mediated activation of osteoclasts and possibly be further promoted by β‐sympathomimetic‐mediated prostaglandin action on the osteoclast. The pathological findings in the fetal rat skeleton cannot be correlated with corresponding findings in human neonates whose mothers were subjected to prolonged therapeutic uterine relaxation with β2‐sympathomimetics, for example. Since the anomalies in the rat disappear spontaneously in the postnatal period, their clinical relevance appears to be slight.
External examination of limb positions in near‐term mouse fetuses: An experimental study and review of the literature published in Teratology
Authors: Pinto‐Machado J. 
Published: June 2005

AbstractThe accidental finding of near‐term mouse fetuses exhibiting limb positions that could have been interpreted as malformations but that were, in fact, spurious, led us to study the posture of the limbs in the offspring of 100 CD‐1 mouse dams. A total of 1,015 fetuses (18 days‐old, vaginal plug: day 0), was examined. Fifteen of these fetuses presented positions that deviated markedly from the norm and were therefore considered to be “unusua,” although the usual position was recovered in 6 of the 15 by placing the affected limb in a standard position and eventually eliciting locomotion. A broad review of the literature was made in order to evaluate our results fully. This review included 43 reports published in Teratology that recorded abnormal limb positions in near‐term mouse and rat fetuses, and another 9 reports where these were not referred to but that included photographs showing such abnormalities. The data obtained from our experimental study and review led us to conclude that for a correct record of abnormal positions in near‐term mouse and rat fetuses, authors must (1) follow appropriate, clearly described technical procedures, including manoeuvers to rule out spurious displacements; (2) give adequate information in the legends of the photographs; (3) use unequivocal terminology; and (4) carry out further research to determine accurately the range in variation of normal limb positions.
Sex difference in susceptibility to teratogenic effect of maternal biotin deficiency in mouse embryos
Authors: Goto Tadashi , Watanabe Toshiaki , Endo Akira 
Published: June 2005

AbstractWhen pregnant mice were fed biotin‐deficient diets, cleft palate occurred more frequently in male fetuses than in female fetuses. Possible underlying mechanisms are speculated on, and some methodological problems in the analysis of sex‐related differences in multiparous animals are discussed.
Electrocardiographic study of rat fetuses exposed to ethylene glycol monomethyl ether (EGME)
Authors: Toraason Mark , Stringer Barbara , Stober Paul , Hardin Bryan D. 
Published: June 2005

AbstractThe widely used industrial solvent ethylene glycol monomethyl ether (EGME) is teratogenic to rats and mice, inducing a variety of heart and major vessel abnormalities. In the present study, electrocardiography was used to evaluate heart function in day 20 rat (Sprague‐Dawley) fetuses from mothers treated on gestation days 7–13 (sperm = day 1) with 0, 25, or 50 mg/kg EGME by gavage in 10 ml/kg water. The increased incidence of fetuses with cardiovascular malformations (primarily right ductus arteriosus and ventricular septal defect) and abnormal electrocardiograms (EKG) was dose dependent. The most prevalent EKG abnormality was a prolonged QRS wave. Mean QRS intervals were not significantly increased by EGME exposure, but there were significantly more litters in the 50‐mg/kg EGME group that had one or more fetuses with QRS complexes of 40 msec or longer. The enhanced duration and the appearance of the aberrant QRS's suggested the presence of an intraventricular conduction delay in these fetuses. Heart rate and other EKG characteristics such as the P wave or P‐R and Q‐T intervals were not significantly affected by exposure to EGME. There did not appear to be an association between abnormal EKG's and fetal heart dysmorphology.
Induction of chick embryo feather malformations by an influenza C virus
Authors: Spence Hilda Adele , O'Callaghan Richard J. 
Published: June 2005

AbstractThe effect of influenza C virus, strain JJ/50, on the development of chicken embryos infected at 10 or 12 days was documented by microscopic techniques, as well as by gross observations of embryos or chicks at hatching. The infected, newly hatched chicks displayed marked abnormalities in their feathering. Such abnormalities were observed neither in mock‐infected embryos nor in embryos injected with virus which had been previously treated with specific influenza C virus antibody. At a microscopic level, the abnormalities apparently are a result of hypertrophy and/or hyperplasia of the developing barb and barbule cells. Further, the additional development of integumental necrotic foci was correlated with the development of relatively high viral titers (>256) as measured by hemagglutination (HA). Embryos infected after 12 instead of 10 days incubation showed normal feathering at hatching. Infection at 12 days, however, was correlated with the development of relatively low viral titers (HA = 4) and limited degeneration of the respiratory epithelium. The relationship of teratogenic effects to the site of viral replication in rapidly differentiating tissue is discussed.
Effect of ethinyl estradiol on the differentiation of mouse fetal testis
Authors: Yasuda Yoshiko , Kihara Takahide , Tanimura Takashi 
Published: June 2005

AbstractIn an evaluation of the effect of ethinyl estradiol (EE) on the differentiation of fetal mouse testes, the ratio of the seminiferous tubular region to the testicular tissue region, the ratio of Sertoli cells to gonocytes in tubule cross sections, and the size of Leydig cells were determined by the Texture Analyse System (T.A.S., Leitz) in histological preparations of the testes. The testes were those of fetuses taken from dams given orally 0, 0.02, 0.2 or 2.0 mg/kg of body weight of EE in olive oil from day 11 through day 17 of gestation and killed at term. From experimental and the control testes, five sections were taken at 40‐μm intervals. The areas of the seminiferous tubular region and the testicular region were determined and the Sertoli cells and gonocytes in tubule cross section were counted in each of the five sections. The diameters of 100 Leydig cells selected at random were averaged. These data were analyzed by Student's t test. The seminiferous tubular region was significantly increased in the testes treated with 0.02 mg/kg of EE and significantly decreased in those treated with 0.2 mg/kg of EE. The number of gonocytes per tubule cross section was significantly increased in the testes treated with 0.02 or 2.0 mg/kg of EE. The number of Sertoli cells per tubule cross section and the number of Sertoli cells per gonocyte were significantly decreased in the experimental testes. The size of the Leydig cells was significantly decreased in the testes treated with 0.2 mg/kg of EE. These findings suggest that prenatal exposure to EE before testicular differentiation affects tubular formation, the proliferation of fetal Sertoli cells, and Leydig cell differentiation, resulting in disturbances of spermatogenesis.
Teratogen update: Clinical aspects of thalidomide embryopathy—A continuing preoccupation
Authors: Newman C. G. H. 
Published: June 2005

AbstractThere is much misinformation in the medical community regarding the thalidomide syndrome. Some physicians and scientists are unaware of the fact that organs other than the limbs were frequently affected. Some believe that thalidomide could produce any type of limb reduction defect. Most were aware of the very narrow period of early organogenesis during which the thalidomide‐type malformations could be produced. Important features include the fact that limb reduction defects were primarily preaxial, included concomitant girdle hypoplasia when limb reductions were severe, were almost universally bilateral and did not include distal transverse‐type defects often called “hemimelia”. While it can be said that some spontaneous (non‐thalidomide) malformations can mimic the thalidomide syndrome, it can also be said that many limb reduction defects can be determined not to have been produced by thalidomide. The risks of the various defects can be estimated following exposure, with most certainty for limb defects, with less certainty for other defects. Many defects were not associated with exposure to thalidomide such as cleft lip and severe mental retardation.
Evaluation of Bendectin embryotoxicity in nonhuman primates: I. Ventricular septal defects in prenatal macaques and baboon
Authors: Hendrickx A. G. , Cukierski M. , Prahalada S. , Janos G. , Rowland J. 
Published: June 2005

AbstractCynomolgus monkeys, rhesus monkeys and baboons were administered 10 to 40 times the human dose equivalent of Bendectin throughout the major period of organogenesis (22(±3)–50 days of gestation). In animals examined prenatally (100 ± 2 days gestation) the total incidence of ventricular septal defects (VSD) was 40% in cynomolgus monkeys, 18% in rhesus monkeys, and 23% in baboons. The majority of VSD involved the muscular portion of the septum. No dose response was evident and there were no other cardiac or extracardiac defects found except for one baboon fetus with multiple defects. No defects were observed in cynomolgus monkeys administered Bendectin for 4‐day periods between 22 and 41 days of gestation. There was no association of Bendectin treatment with any noncardiac defect. In cynomolgus and rhesus monkeys examined at term there was one mitral valve defect and no incidence of VSD. The increased incidence of VSD observed prenatally in all three species and the absence of defects in macaques at term suggests a delay in closure of the ventricular septum in treated animals. The Bendectin‐treated monkey may be a suitable model for the study of the pathogenesis of VSD and the mechanism of spontaneous closure of the defect.
Morphological and biochemical aspects of monofunctional phosphoramide mustard teratogenicity in rat embryos cultured in vitro
Authors: Mirkes P. E. , Greenaway J. C. , Hilton John , Brundrett Robert 
Published: June 2005

AbstractDay 10 rat embryos were exposed in vitro to a monofunctional analog of phosphoramide mustard (MPM) at concentrations of 25 to 200 μg/ml (144 to 1,156 × 10−6 M). After a 24‐hour exposure, embryos exhibited a dosedependent decrease in growth parameters (crown‐rump length, number of somites, and protein content) as well as incidence of malformations. Abnormal embryos were characterized by hypoplasia of the prosencephalon as well as hypoplalsia of the mandibula arches, tail, and limb buds. Histological analysis revealed abnormal levels of necrotic cells, particularly in the neuroepithelium and surrounding mesenchyme. In all respects embryos exposed to MPM could not be distinguished from embryos exposed to phosphoramide mustard. We also determined using mouse L1210 cells that at the maximum nonlethal concentration used in our embryo exposure experiments, MPM did not cause DNA cross‐linking but did cause single‐strand DNA breaks. Phosphoramide mustard, at concentrations teratogenic to embryos in vitro, did produce DNA cross‐linking. Taken together, our results indicate that although cyclophosphamide (CP)‐induced DNA cross‐linking may play a role in CP teratogenesis, DNA cross‐linking is not an absolute requirement.
Fetal development in mice exposed to isoflurane
Authors: Mazze Richard I. , Wilson Anne I. , Rice Susan A. , Baden Jeffrey M. 
Published: June 2005

AbstractThe developmental toxicity of trace (0.006%), subanesthetic (0.06%), and light anesthetic (0.6%) exposure to isoflurane was examined in Swiss/Webster mice. No adverse effects were demonstrated following exposure of dams to 0.006% (n = 26) and 0.06% (n = 27) isoflurane for 4 hr daily on days 6–15 of pregnancy. Exposure to 0.6% isoflurane (n = 23) for the same period resulted in significantly decreased fetal weight, decreased skeletal ossification, minor hydronephrosis, and increased renal pelvic cavitation. The incidence of cleft palate also was significantly increased, abnormalities occurring in 12.1% of fetuses and affecting 11 of 23 litters. This incidence was considerably higher than that of the combined treatment and colony control groups (0.75%) and those that we have found in previous experiments with this mouse strain following exposure to halothane (1.2%) or enflurane (1.9%).
Lead‐induced early lesions in the brain of the chick embryo
Authors: Narbaitz Roberto , Marino Irma , Sarkar Kiriti 
Published: June 2005

AbstractA single dose consisting of a solution of lead nitrate containing 1 mg lead in 0.1 ml distilled water was injected into the air chamber of chicken eggs on the tenth day of incubation. The injected embryos were killed 24, 48, or 72 hours after the injection. Control embryos were injected with a similar volume of distilled water or of an equimolar calcium nitrate solution on the tenth day and killed 72 hours after. Portions of the optic lobes were processed for their electron microscopic study. Multiple hemorrhagic foci appeared 24 hours after the administration of lead. Red blood cells were found to exit the blood vessels through the spaces between otherwise normal‐looking endothelial cells; tight junctions were always found blocking the interendothelial spaces except during the migration of red blood cells through them. Vacuolization of the cytoplasm and mitochondrial swelling and disorganization were observed in the endothelial cells only during the third day after the injection. Similarly, histological and ultrastructural alterations of nerve cells were only found on the third day after the treatment. Hemorrhagic foci were never found in control embryos. Our observations are consistent with the idea that the hemorrhages constitute the primary lesion produced by lead. They also suggest that the hemorrhages are not the result of rupture of previously altered endothelial walls but occur by diapedesis through the interendothelial clefts.
Embryotoxicity of a single dose of medroxyprogesterone acetate (MPA) and maternal serum MPA concentrations in cynomolgus monkey (Macaca fascicularis)
Authors: Prahalada S. , Carroad E. , Cukierski M. , Hendrickx A. G. 
Published: June 2005

AbstractA single dose of MPA (Depo‐Provera; Upjohn Co., Kalamazoo, Michigan) was administered intramuscularly to 12 time‐mated pregnant cynomolgus monkeys on day 27 (±2) of gestation at 25 mg/kg or at 100 mg/kg. Maternal blood samples were collected immediately prior to MPA injection and then at regular intervals until cesarean section at term (day 152 ± 3). Infants in both dose groups had external genital abnormalities. Female infants in the low–dose groups had partial or complete labial fusion, prominent median raphe, and clitoral hypertrophy; at high doses (100 mg/kg), the female infants had complete labial fusion and a distinct penile urethra. MPA had an opposite effect on external genitalia of male infants. The penis was short and the scrotal swelling was absent or less conspicuous, and two males had hypospadias. The adrenal glands were significantly smaller (P < 0.05) in infants of both sexes treated with 100 mg/kg. One of the infants treated with 25 mg/kg of MPA had a muscular ventricular septal defect. Serum concentrations of MPA were determined by radioimmunoassay in eight pregnant monkeys. In the 25 mg/kg group the patterns of MPA profiles in the serum were similar in all four animals. An initial peak occurred at 24–48 hr postinjection (2.7–9.6 ng/ml), followed by a slight decrease at 3 days postinjection (gestational day 30), and then a steady increase to maximum levels of 10–14 ng/ml occurring between gestational days 37 and 50. Serum levels gradually declined to concentrations below 5 ng/ml by midgestation in three of four monkeys. By comparison, both the patterns and magnitude of MPA concentration showed great interanimal variation in the 100mg/kg group. MPA was present in cord blood at measurable concentrations in infants at both dose groups; the levels ranged from 0.6 to 8.3 ng/ml, corresponding to 40–72% of the maternal concentrations. These results demonstrate that a single injection of MPA during early pregnancy causes selective embryotoxicity in both male and female fetuses. Presence of high levels of MPA in maternal sera during the critical period of genital development can cause specific genital defects; however, the exact mechanism by which MPA causes these paradoxical genital abnormalities is unknown.
Histological changes induced in developing limb buds of C57BL mouse embryos submitted in utero to the combined influence of acetazolamide and cadmium sulphate
Authors: Milaire J. 
Published: June 2005

AbstractMicroscopic defects in limb buds of C57BL mouse embryos after the combined teratogenic action of acetazolamide plus cadmium sulphate administered on day 9 of gestation were studied in serial sections. Postaxial deficiencies observed in 12–15‐day embryos and affecting preferentially the right forelimbs were classified in nine morphological types according to increasing amounts of missing parts. Type X defect consists of a nearly complete amelia in which all four limbs are represented only by the girdle and proximal end of the stylopod. Type XI abnormality appears as an intermediate reduction affecting the area of digit IV. In addition to modifications of the forelimb bud shape detected from the 10‐day stage onwards, observations made 24 and 48 hr after treatment confirmed that the postaxial defects result from an absolute lack of postaxial mesoderm occurring without cell necrosis as a consequence of a postaxial shortening of the apical ectodermal ridge (aer). In 10‐day embryos, the latter appears shortened and hypertrophied; it is later fragmented into alternate thick and thin portions in 11‐day affected limb buds. These ectodermal changes might account for the genesis of all types of defects observed. Untreated 9‐day embryos with 12–25 pairs of somites display a number of asymmetries between their right and left forelimb territories: Until the 19‐somite stage, the vascular supply to that area is provided exclusively by the umbilical vein, which is larger on the right side; the initial amount of somatopleural limb mesoderm is greater in the right rudiment and the genesis of its aer is slightly protracted as compared to the left one. These asymmetries might contribute to the right side predominance of the forelimb defects induced by acetazolamide and cadmium.
Studies of human achondroplasia: Oxidative metabolism in tissue culture cells
Authors: Mackler Bruce , Grace Richard , Davis Kenneth A. , Shepard Thomas H. , Hall Judith G. 
Published: June 2005

AbstractMitochondria prepared from the first growth of cells (fibroblasts) from skin biopsies from homozygous (but not heterozygous) achondroplastic human subjects were unable to carry out oxidative phosphorylation. However, successive crops of cells gained the ability to phosphorylate with normal P:O ratios with pyruvate‐malate and succinate as substrates. Concentrations of cytochromes a + a3 were markedly and significantly lower in homogenates of homozygous achondroplastic tissue culture cells than in homogenates of normal cells. Levels of cytochromes a + a3 in the heterozygous achondroplastic cells were intermediate between the levels in normal cells and the homozygous achondroplastic cells. Activities of the mitochondrial oxidative systems (NADH, succinic and cytochrome oxidases) were not significantly lower in the achondroplastic cell preparations than in normal cell preparations under standard assay conditions (saturation levels of oxygen).