bluuebunny/crossref_metadata_2025 huggingface dataset:
Occurrence of embryotoxicity in mouse embryos following in utero exposure to 2′‐deoxycoformycin (pentostatin)
Authors: Airhart Mark J. , Robbins Charles M. , Knudsen Thomas B. , Church Joyce K. , Skalko Richard G.
Published: June 2005

Previous investigations had shown that i.p. injection of 2′‐deoxycoformycin (dCF; pentostatin; 5 mg/kg) on either E7 or E8 into pregnant mice results in a 61–81% resorption rate at E17. The incidence of visible gross malformations among the surviving conceptuses was exceptionally low (3%) at the time of necropsy on E17 and was unrelated to dCF dose (Knudsen et al., Teratology, 40:5–626, '89; Teratology, 45:91–103, '92). These findings demonstrated the embryotoxicity of dCF but provided no clues as to the site(s) of dCF action. To define the lesion site(s), we have now examined embryos at 72 h(E10), 96 h (E11), and 120 h (E12) following administration of a highly embryotoxic dose of 5 mg dCF/kg to dams on E7. Deoxycoformycin caused multiple abnormalities and growth retardation, and the temporal sequence between maximal abnormal embryo incidence and resorption frequency was established. The quantitative data show that the maximal occurrence of abnormal embryos on E10 (71%) was followed by a maximal resorption rate on E12 (78%). There was a strong correlation (r = −0.82; P < 0.05) between the rapid decline of percent abnormal embryos over E10–E12 and the simultaneous increase in resorption rate, with linear regression analysis showing nearly equal but opposite slopes (−31.2% vs. +35.8% per gestational day, respectively). This suggests that one or more of the abnormalities seen at E10 is associated with the death and resorption of the embryo at E12. The dCF treatment perturbed a wide spectrum of developmental events, including neural tube closure, craniofacial and limb development, turning of the embryo, and growth retardation. None of the individual abnormalities, however, can quantitatively account for the high percentage of dead and resorbed embryos. Therefore, the specific cause of dCF‐induced embryolethality is not clear. There is evidence both for direct dCF toxicity at specific embryonic sites as well as for a generalized retardation in the rate of development. © 1993 Wiley‐Liss, Inc.
Comparative teratogenicity and metabolism of all‐trans retinoic acid, all‐trans retinoyl β‐glucose, and all‐trans retinoyl β‐glucuronide in pregnant Sprague‐Dawley rats
Authors: Gunning Desirée B. , Barua Arun B. , Olson James Allen
Published: June 2005

When single large equimolar doses (0.38–0.41 mmol/kg BW) of all‐trans retinoic acid (RA), all‐trans retinoyl β‐glucose (RBGL), and all‐trans retinoyl β‐glucuronide (RBG) are administered orally in oil on day 8.5 of pregnancy to Sprague‐Dawley rats, RA and RBGL proved highly teratogenic, whereas RBG was not. Indeed, fetuses from RBG‐treated dams were 16% heavier (P < 0.01) than control fetuses. After dosing with RA and RBGL, RA appeared in large amounts within 0.5 h in the maternal plasma and within 1.0 h in the embryo. In contrast, orally administered RBG seemed to be absorbed much more slowly, to be converted very slowly to RA, and not to accumulate either as RBG or as RA in the embryo. When incubated in vitro with embryos and attached membranes, however, both all‐trans RBG and all‐trans RA were partially converted to 13‐cis RA. The nonteratogenicity of RBG, in contrast to RA, seems to be due to a much slower rate of GI absorption, a slow rate of hydrolysis to RA, a limited passage from the maternal circulation into the embryo, and a lower inherent toxicity. © 1993 Wiley‐Liss, Inc.
Development of in vitro fertilized mouse embryos exposed to ethanol during the preimplantation period: Accelerated embryogenesis at subtoxic levels
Authors: Leach Richard E. , Stachecki James J. , Armant D. Randall
Published: June 2005

This study examined the effects of ethanol (EtOH) on mouse preimplantation development using an in vitro culture method. Embryos at the 1‐cell, 2‐cell, or 4‐cell stage were exposed for 24 h to medium containing EtOH, then further cultured without EtOH to determine their ability to form blastocysts and to eventually hatch from the zona pellucida. EtOH exposure either arrested or enhanced normal development, depending on dose and embryonic stage of exposure. Exposure of 1‐cell and 2‐cell embryos to 1.6% (w/v) EtOH decreased blastocyst formation and hatching, and exposure of 1‐cell embryos to 0.4% EtOH inhibited their development. At 0.1%, EtOH had an opposite effect, causing an increase in the percent blastocyst formation of treated 1‐cell and 2‐cell embryos. Neither inhibition nor stimulation of blastocyst formation occurred in 4‐cell embryos exposed to 0.1–1.6% EtOH. Using an in vitro outgrowth model of implantation, embryos that reached the blastocyst stage were further tested for their ability to produce differentiated trophoblast cells. Blastocysts previously exposed to 0.1% EtOH during the 1‐cell stage appeared to form adhesive trophoblasts earlier than control embryos, indicating that EtOH exposure can induce precocious differentiation of the trophoblast cells. The EtOH treated blastocysts contained significantly more cells than control blastocysts. These results indicate that EtOH can alter preimplantation development by either inhibiting or accelerating cell growth and differentiation. © 1993 Wiley‐Liss, Inc.
Renal dysplasia, megalocystis, and sirenomelia in four siblings
Authors: Selig Abby M. , Benacerraf Beryl , Greene Michael F. , Garber Mary‐Frances , Genest David R.
Published: June 2005

First degree relatives of infants with bilateral renal agenesis or dysplasia have an increased risk of renal abnormalities including renal agenesis. We report a family in which four successive offspring exhibited a previously undescribed combination of congenital lethal renal disorders: bilateral renal dysplasia, megalocystis secondary to urethral obstruction and, sirenomelia with associated renal agenesis. © 1993 Wiley‐Liss, Inc.
Fetal dexamethasone exposure interferes with establishment of cardiac noradrenergic innervation and sympathetic activity
Authors: Bian Xiaopeng , Seidler Frederic J. , Slotkin Theodore A.
Published: June 2005

Endogenous glucocorticoids provide natural differentiation signals for adrenergic neurons, and exposure to high exogenous steroid levels thus disrupts the timing of neuronal maturation. In the current study, pregnant rats were given 0.05, 0.2, or 0.8 mg/kg dexamethasone on gestational days 17, 18, and 19, and the effects on development of cardiac sympathetic function were assessed postnatally in the offspring. Dexamethasone produced a dose‐dependent retardation of body and heart weight gains; at the highest dose, heart weight deficits were smaller than those for body weight, producing a relative cardiomegaly. The weight effects were accompanied by abnormalities of noradrenergic innervation, as assessed with measurements of norepinephrine levels and turnover. Norepinephrine levels were significantly reduced at all doses of dexamethasone, with the magnitude of effect exceeding that on heart or body weights; thus the levels were reduced even when corrected for tissue weight (ng norepinephrine/g heart weight). Norepinephrine turnover, a measure of neuronal impulse activity, showed delayed development at the lowest dose of dexamethasone and displayed profound suppression throughout development at the higher doses. Adverse effects of dexamethasone on norepinephrine turnover were still apparent in young adulthood, despite the recovery of weight variables to within 15% of normal values. In light of the release of steroids during maternal stress and the use of steroids in the therapy of neonatal respiratory distress, developing adrenergic neurons are likely to be targeted for adverse effects even when standard growth indices have normalized. © 1993 Wiley‐Liss, Inc.
Embryotoxic effects of chlorobutanol in cultured mouse embryos
Authors: Smoak Ida W.
Published: June 2005

Chlorobutanol (CB) is a commonly used preservative which is added to numerous pharmaceutical preparations, and it is the active ingredient in certain oral sedatives and topical anesthetics. Chlorobutanol has demonstrated adverse effects in adult tissues, but CB has not been previously investigated for its effect on the developing whole embryo. The method of wholeembryo culture was used in this study to expose mouse embryos during two stages of organogenesis to CB at final concentrations of 0 (control), 10, 25, 50, 100, and 200 μg/ml. Embryos were evaluated for heart rate (HR), malformations, and somite number, and embryos and visceral yolk sacs (VYSs) were assayed for total protein content as a measure of overall growth. Neurulating (3–6 somite) embryos were malformed and growth retarded by exposure to CB concentrations ⩾25 μg/ml, with decreased VYS growth at ⩾50 μg/ml and decreased HR at ⩾100 μg/ml CB. Early limb‐bud stage (20–25 somite) embryos were malformed at CB concentrations ⩾50 μg/ml and growth retarded at ⩾100 μg/ml, with decreased VYS growth at 200 μg/ml and decreased HR at ⩾100 μg/m, CB. Thus, CB produces dysmorphogenesis in mouse embryos in vitro, and neurulating embryos are somewhat less sensitive than early limb‐bud stage embryos. The concentrations of CB that interfere with normal embryonic development are within the range of human blood levels measured following multiple doses of CB. Preparations containing CB should be used with caution during pregnancy, particularly when repeated dosing may allow accumulation of CB to potentially embryotoxic levels. © 1993 Wiley‐Liss, Inc.
The role of oxygenation in embryotoxic mechanisms of three bioreducible agents
Authors: Barber C. V. , Fantel A. G.
Published: June 2005

Many xenobiotics used in the treatment of hypoxic pathogens and tumors require reductive bioactivation under anaerobic conditions for maximal effectiveness and/or toxicity. A number of agents of this type have been shown to be teratogenic in vitro and/or in vivo. Early conceptuses may be vulnerable to these agents because they exist in a relatively anaerobic environment and have the capacity to perform reductive metabolism. It has been hypothesized that the single electron redox potential of bioreducible agents plays a dominant role in the capacity to induce anomalies. We examined the in vitro embryotoxicity in rats of three bioreducible drugs of similar redox potential under normoxic and hypoxic conditions as well as the capacity of those drugs to redox cycle and to damage DNA in embryonic tissue. Adriamycin, mitomycin C, and niridazole were shown to have differential embryotoxic responses in vitro to altered oxygenation. Studies of the bases of drug action showed (1) Adriamycin induces DNA strand breaks at concentrations that correlate well with embryolethality; (2) Mitomycin C does not induce strand breaks, but its dysmorphogenicity is increased by hypoxia; and (3) Niridazole does not produce DNA damage but appears to induce asymmetric malformations by depleting embryonic oxygen through redox cycling. Together the studies show that dysmorphogenic and embryolethal effects may result from separate mechanisms and that oxygenation plays an important role in those mechanisms. © 1993 Wiley‐Liss, Inc.
Ellagic acid embryoprotection in vitro: Distribution and effects on DNA adduct formation
Authors: Frank Anthony A. , Collier John M. , Forsyth Carol S. , Zeng Wenguang , Stoner Gary D.
Published: June 2005

Ellagic acid (EA) is a naturally occurring plant phenol that was recently demonstrated to protect cultured rat embryos from the embryotoxic effects of N‐methyl‐N‐nitrosourea (MNU). The teratogenic mechanism of action of MNU, as well as other methylating agents, is debated: both cell death and mutation have been proposed. In some model systems, EA has been reported to selectively decrease the mutagenic DNA adduct O6‐methylguanine (O6MG) when compared to the cytotoxic DNA adduct N7‐methylguanine (N7MG). The present study was initiated to determine 1) the distribution of 14C‐EA and 3H‐MNU in the rat whole embryo culture model system and 2) the effects of EA on MNU‐induced DNA adduct formation in this model system. 14C‐EA (50 μM for 2 hr, known embryoprotective concentration; no MNU added) was used to demonstrate access of EA to the embryo within the 2 hr exposure period. The majority of EA (99.5%) remained in the media while tissue concentrations of 57.0 and 47.9 pmol/mg were attained in the yolk sacs and embryos, respectively. Similarly, MNU (75 μM for 1 hr, known effective concentration; no EA added) was distributed between the media, yolk sacs, and embryos at 99.7%, 73.7 and 112.9 pmol/mg, respectively. When non‐radiolabeled EA (50 μM for 2 hr) was used to protect embryos prior to exposure to 3H‐MNU (75 μM for 1 hr), the distribution of MNU in the model system was unchanged. When O6MG and N7MG addjuction rates in yolk sac DNA, embryo DNA, and pooled data were compared between protected (50 μM EA for 2 hr followed by 75 μM MNU for 1 hr), and non‐protected tissues (vehicle for 2 hr followed by 75 μM MNU for 1 hr), EA decreased O6MG formation by 35.2–49.7% while N7MG was not decreased. The decreases in O6MG formation were only statistically significant (P < 0.05) when yolk sac and embryo data were pooled. EA apparently interrupts the embryotoxic pathogenesis of MNU by decreasing O6MG formation within the embryo and/or yolk sac. © 1993 Wiley‐Liss, Inc.
External craniofacial features, body size, and renal morphology in prenatal Brachyrrhine mice
Authors: Ma Wenbin , Lozanoff Scott
Published: June 2005

The Brachyrrhine (Br) semidominant mouse mutant provides a useful model for studying factors responsible for midfacial hypoplasia. In order to determine early morphogenetic events responsible for midfacial hypoplasia in these mice, prenatal mutants must be differentiated from nonaffected littermates. The purpose of this study was to determine whether prenatal offspring from Br matings could be separated morphologically into groups of normal or midfacially deficient embryos. Thirty embryos resulting from Br matings were collected between day 15 and birth (Theiler stages 23–27). Qualitative observations on craniofacial morphology as well as renal morphology and histology suggested that embryos segregated into two distinct groups. External craniofacial and body measurements, collected from the embryos, as well as renal volumes, determined from computerized reconstructions of the kidneys, were subjected to quantitative analyses. A discriminant function analysis segregated the sample into two groups based primarily on midfacial length and renal volume. Bivariate regression analysis showed that midfacial length and renal volume differed significantly, and cranial length marginally so, between the two groups. The results indicate that a proportion of prenatal offspring from Br matings exhibits midfacial and renal hypoplasia and that these animals segregate completely from nonaffected embryos. © 1993 Wiley‐Liss, Inc.
Expression of the IV (reversed and/or heterotaxic) phenotype in SWV mice
Authors: Layton W. M. , Layton M. W. , Binder Michael , Kurnit David M. , Hanzlik Andrzej J. , Van Keuren Margaret , Biddle Fred G.
Published: June 2005

Approximately 50% of iv/iv mice have situs inversus (mirror image reversal of viscera) and 40% have heterotaxia (anomalous arrangement of viscera). The occurrence of heterotaxia is independent of situs. Using the cross‐intercross breeding system to put the iv gene on the SWV background, an occasional presumed iv/ + mouse was found that had an IV (situs inversus and/or heterotaxic) phenotype. Testcrosses of these reversed animals indicated an iv/ + genotype. Since iv is linked tightly to Igh‐C on chromosome 12, we inferred the genotype with a polymorphism of Igh‐C demonstrated using the polymerase chain reaction (PCR). This confirmed them to be iv/ +. The expression of the IV phenotype in animals heterozygous for the iv gene may be due to an interaction of iv with an autosomal recessive gene found in SWV. We have not found the IV phenotype in heterozygous iv/+ mice following placement of the iv gene on six other inbred strains. Rarely, we also found that presumed SWV +/+ mice had the IV phenotype. Test matings of these phenodeviants, corroborated by PCR, have confirmed them to be +/+. Although the phenotypes of the affected SWV +/+ and iv/ + mice resembled those found in iv/iv mice, the occurrence of situs inversus and heterotaxia were not independent of each other, and most of the SWV mice with the IV phenotype had heterotaxia with situs solitus.

This infrequent dominant expression of the iv gene has so far only been seen when iv is on the SWV background. These findings are consistent with the idea that this phenomenon is due to the interaction of the iv gene with another gene found so far only in the SWV strain. © 1993 Wiley‐Liss, Inc.
The Teratogenic effects of salicylic acid on the developing nervous system in rats in vitro
Authors: Joschko Marion A. , Dreosti Ivor E. , Tulsi Ram S.
Published: June 2005

Aspirin ingestion in humans and animals has been reported to lead to a range of undesirable outcomes, including fetal death, growth retardation, and congenital abnormalities. Rat embryos were cultured for 48 h in 100–300 μg/ml of salicylic acid, a metabolite of aspirin, days 9.5–11.5 of gestation. When compared to growth in control embryos, a significant dose‐dependent decrease in crown‐rump lengths, somite numbers, and yolk sac diameters was observed. There was also a significant increase in overall dysmorphology, including eye, branchial arch, and heart anomalies, and an absence of forelimb buds. The neural tube was especially vulnerable and had frequently failed to close. Cellular and ultrastructural examination revealed extensive cell death in the neuroepithelium, with a lesser effect on the mesenchymal cells. Large condensed blebs projected into the ventricular lumen, and cell membranes as well as the basal lamina were severely disrupted, with all cytoplasmic organelles affected in dying cells. It is likely that the extensive cell necrosis and blebbing in the developing neuroepithelium at the site of neural tube fusion may be involved in failed neurulation, while necrosis at other sites in the cranial neuroepithelium may be linked with previously reported intellectual and behavioural abnormalities. © 1993 Wiley‐Liss, Inc.
Effects of fetal dexamethasone exposure on postnatal control of cardiac adenylate cyclase: β‐adrenergic receptor coupling to GS regulatory protein
Authors: Bian Xiaopeng , Seidler Frederic J. , Olsen Catherine , Raymond John R. , Slotkin Theodore A.
Published: June 2005

In the adult, glucocorticoids have been shown to upregulate β‐adrenergic control of adenylate cyclase by a variety of mechanisms; glucocorticoids are also thought to play a role in development of cardiac adrenergic function. In the current study, pregnant rats were given 0.2 mg/kg of dexamethasone on gestational days 17, 18, and 19 and the effects on the development of cardiac β‐receptors and their linkage to the stimulatory G‐protein, GS, were examined at 4 days postpartum. β‐Receptor numbers and affinity were unaffected by dexamethasone exposure, nor was there any change in the ability of the GTP analog, Gpp(NH)p, to shift the affinity state of the receptor. Addition of Gpp(NH)p to cardiac membranes enhanced basal and isoproterenol‐stimulated adenylate cyclase activity, but the total response to isoproterenol, with or without Gpp(NH)p, represented a very small fraction of total enzymatic activity. Quantitative analysis of GS indicated no changes attributable to dexamethasone treatment. Although prenatal dexamethasone has been shown to increase adenylate cyclase reactivity to β‐adrenergic input, the effect appears to be at the level of the catalytic subunit of adenylate cyclase, rather than at receptor or G‐protein stages. Abbreviations: ANOVA, analysis of variance, Gpp(NH)p, 5′‐guanylimidodiphosphate. © 1993 Wiley‐Liss, Inc.
Teratogenesis associated with oxydemeton‐methyl in the stage 12 chick embryo
Authors: Lenselink Daniel R. , Midtling John E. , Kolesari Gary L.
Published: June 2005

The teratogenic potential of oxydemeton‐methyl (ODM) was investigated using a stage specific localized topical method of application to the stage 12 chick embryo. A dose of 0.01, 0.05, 0.10, 0.50, 1.0, or 2.0 mg/embryo was applied to the vitelline membrane directly above the stage 12 embryo. The embryo was then returned to the incubator and monitored daily until stage 41 (15 day). At stage 41 the embryo was autopsied and examined for gross external and internal malformations, wet weight, and crown‐rump length. Experimental data was compared to unopened and saline treated controls. At doses less than 0.50 mg/embryo, survival rates were high (>80%) but when that dose was exceeded, the survival rate fell significantly (P<0.001). A dose‐dependent increase in malformation rate was seen in all treatment groups with 0.10 mg/embryo, producing a maximum malformation rate (19/33) with minimum mortality (3/36). Crown‐rump lengths and wet weights were significantly less than controls in all treatment groups (P<0.001). Anomalies were primarily seen in the musculoskeletal (ventral midline, limb, and neck) and cardiovascular (ventricular septum and aortic arches) systems. Thoracogastroschisis and ventricular septal defects were the most common combination of malformations. Our data suggest that ODM is teratogenic when topically applied to the stage 12 chick embryo. © 1993 Wiley‐Liss, Inc.
Fetal development in the rat following disruption of maternal renal function during pregnancy
Authors: Kavlock Robert J. , Logsdon Tina , Gray Jacqueline A.
Published: June 2005

Pregnant Sprague‐Dawley rats received subcutaneous injections of mercuric chloride (1–4 mg/kg) on either gestation day 7, 9, 11, or 13 to determine effects of altered maternal renal function on embryonic and fetal development. Maternal renal function, assessed by urinanalysis, was markedly disrupted for at least 48 hours after treatment and resulted in decreased maternal body weight gain. Residual effects on maternal kidney weight were evident on GD 21 when the females were killed and the fetuses removed and examined for visceral and skeletal development. We did not observe an increased incidence of malformations in the offspring for exposure on any day of gestation. Maternal exposure to mercuric chloride slightly impaired fetal growth over several gestational exposures periods and changed the pattern of rib formation when exposure occurred early in organogenesis. The extent of the changes could not, however, be related to the immediate degree or duration of altered maternal renal function. Rather, we found correlations between lasting effects of exposure as measured by maternal renal weight on GD 21 and supernumerary lumbar rib induction on GD 7 and 9; while for the relationship with fetal weight, the strongest correlation with maternal kidney weight occurred following exposure on GD 9 (p<0.01), with weaker correlations (p<0.10) for GD 7 and 13 exposures. Maternal serum urea was negatively correlated with fetal weight from the GD 7 exposure. This study supports the concept that some specific forms of maternal toxicity may be associated with limited manifestations of developmental toxicity, but, in general, embryonic development was observed to proceed normally in the presence of marked disruptions in maternal renal physiology. Maternal toxicity, especially as routinely measured in developmental toxicity studies, cannot be looked upon as a single disease. Instead, each manifestation must be examined for what it signifies to the physiology and well being of the female and for cause‐and‐effect relationships with fetal observations. Maternal toxicity and developmental toxicity should not be etiologically linked solely because of their concurrent appearance on the dose‐response curve. © 1993 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Toxicokinetics and structure‐activity relationships of nine para‐substituted phenols in rat embryos in vitro
Authors: Fisher Henry L. , Sumler Martha R. , Shrivastava S. P. , Edwards Brenda , Oglesby Linda A. , Ebron‐McCoy Marian T. , Copeland Frank , Kavlock Robert J. , Hall Larry L.
Published: June 2005

The purpose of this study was to examine the toxicokinetics of embryo uptake following exposure to a variety of chemically related phenols in rat embryo culture. The uptake of nine radiolabeled para‐substituted phenols by day 10(9–13 somite stage) rat embryos in vitro was determined from 1 to 42 hrs after being placed in culture media containing various phenols. Uptake was rapid, having a half‐life of 3 hr or less, with 7 of the nine compounds having uptake half‐times of less than one hour. The equilibrium concentration in the embryo ranged from 53 to 136% of the media concentration, indicating only a factor of 2 in maximum discrimination against the compound for any of the phenols studied. The fraction of radioactivity remaining unbound in the media decreased with increasing log P (octanol/water partition coefficient). The binding was calculated to be 50% for log P = 1.77 from the fitted regression equation and decreased by a factor of 5.9 for every decade increase in P.

When hepatocytes were also present in the media the equilibrium concentration in the embryos was less than when hepatocytes were absent. With the limited data, four of the phenols appeared to have no (i.e., zero) equilibrium level when hepatocytes were present. Thus the metabolites produced by the hepatocytes appeared to have less affinity for the embryo than the parent phenol. Toxicodynamic information as given by the effective concentration of the phenol in the embryo to cause somite or tail teratological effects was best predicted by the measured unbound fraction. © 1993 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
A morphological and family study on isolated terminal transverse type of congenital limb deficiency in Hungary, 1975–1984
Authors: Czeizel A. E. , Vitéz M. , Kodaj I. , Lenz W.
Published: June 2005

A population‐based and validated data set of 195 cases with isolated terminal transverse‐type congenital limb deficiency was evaluated in Hungary, 1975–1984. Terminal transverse types of congenital limb deficiency are not usually associated with non‐limb defects, and typically only one limb is affected. Upper limb is more frequently affected than lower (9:1) in monomelic cases. The left side and females are affected more often in upper limbs while lower limb defects are evenly distributed between right and left sides and both sexes. Familial occurrence was not found. © 1993 Wiley‐Liss, Inc.
Facial features of infants exposed prenatally to cocaine
Authors: Fries Melissa H. , Kuller Jeffrey A. , Norton Mary E. , Yankowitz Jerome , Kobori Joyce , Good William V. , Ferriero Donna , Cox Victoria , Donlin Susan Seto , Golabi Mahin
Published: June 2005

Thirty two infants referred for in‐patient genetics evaluation at the University of California at San Francisco, 1987–1992, were found to have a history of maternal cocaine use. Genetics reports and medical records were reviewed on all these infants to identify features distinctive for cocaine exposure. Among these 32 cases, 14 infants were exposed only to cocaine; 18 were exposed to alcohol and cocaine. The infants evaluated displayed a distinctive phenotype, consisting of neurologic irritability, large fontanels, prominent glabella, marked periorbital and eyelid edema, low nasal bridge with transverse crease, short nose, lateral soft tissue nasal buildup, and small toenails. Features consistent with the fetal alcohol syndrome appeared distinct and coexistent with the other described facial findings. Other severe abnormalities included cleft lip/palate, atypical facial cleft, abnormal BSER, intraventricular hemorrhages, arthrogryposes, and genitourinary abnormalities. Forty percent of the infants were born prematurely; 28% were small for gestational age; 43% showed head circumference values less than the 10th percentile. We conclude that these findings may be distinctive for a diagnosis of fetal cocaine syndrome; such findings should be further established by a future blinded prospective study of mothers and neonates.© 1993 Wiley‐Liss, Inc.
Effects of low level prenatal 60Co gamma‐irradiation on postnatal growth and behavior in mice
Authors: Wang Hong , Chen Deqing , Gao Changwen , Zhou Xiangyan
Published: June 2005

Pregnant Kun Ming strain mice were exposed to a total dose of 0, 0.1, 0.2, or 0.4 Gy from 60Co γ‐rays from the 13th to the 18th days of gestation. An overall delay of the appearance of two physiologic markers (pinna detachment, eye opening) and the age of acquisition of four reflexes (surface righting, air righting, auditory startle, visual placing) was observed in offspring exposed to 0.2 or 0.4 Gy in utero. Postnatal growth retardation, shortened length of hanging time, inhibited exploratory activity in the hole board test (decreased number of head‐dipping), and hyperactivity in the open field test (shortened latency to leave the center area and increased number of squares entered) were also found among the offspring exposed to 0.2 Gy or more in utero. The results indicate that 0.1–0.2 Gy may represent a threshold range in mice for certain physiologic and behavioral effects resulting from continuous exposure to 60Co γ‐rays on the 13th–18th days of gestation. © 1993 Wiley‐Liss, Inc.
Activation of apoptosis in early mouse embryos by 2′‐deoxyadenosine exposure
Authors: Gao Xiang , Blackburn Michael R. , Knudsen Thomas B.
Published: June 2005

Adenosine deaminase (ADA) catalyzes the irreversible hydrolytic deamination of adenosine and deoxyadenosine to nontoxic derivatives. The importance of this reaction in the female reproductive tract of mice is suggested by pronounced utero‐placental expression of ADA, and by embryolethality of the potent ADA‐inhibitor deoxycoformycin (dCF) on day 7–8 of gestation. The present study investigated the effects of dCF, adenosine, and deoxyadenosine on the mouse neurula. Morphological cell death was monitored by the acridine orange reaction (AOR), and biochemical cell death by internucleosomal DNA cleavage (IDC). A strong AOR appeared in day 7–8 embryos between 3 and 4.5 hr post‐exposure to dCF in utero; there was no apparent effect on day 6 or day 9 embryos. Most embryonic tissues were responsive, although the heart and extraembryonic membranes were resistant. Up to 75% of the embryonic chromatin was degraded in a regular pattern in concert with the AOR. Immediate activation of “whole‐body” apoptosis was reproduced in short‐term whole embryo culture with 0.1 mM deoxyadenosine in the presence of 0.01 mM dCF. This was not activated by exposure to dCF alone nor to adenosine; however, high concentrations of adenosine completely blocked the response to deoxyadenosine, whereas niacinamide inhibited the AOR without changing IDC. The cytotoxic effect of deoxyadenosine was correlated with an expansion of embryonic dATP pools determined by high‐performance liquid chromatography analysis. The results suggest that deoxyadenosine is the embryotoxic metabolite which accumulates in the antimesornetrium of pregnant mice treated with dCF. Exposure to this metabolic toxin activates apoptosis in day 7–8 embryos through an adenosine‐sensitive, NAD‐dependent mechanism. © 1994 Wiley‐Liss, Inc.
Comparison of four spatial maze learning tests with methylnitrosourea‐induced microcephaly Rats
Authors: Akaike M. , Ohno H. , Tsutsumi S. , Omosu M.
Published: June 2005

The usefulness of four spatial maze learning test methods, single T‐maze, Biel water maze, Morris water maze, and radial eightarm maze, was compared using rats with different degrees of microcephaly, which were induced by single intraperitoneal injection with 3 and 5 mg/kg of methylnitrosourea (MNU) on day 13 of gestation. The single T‐maze test did not detect a learning defect in either MNU group. In the Biel water maze test, the swimming time and number of errors were increased in the 5 mg/kg group, but these parameters were comparable to the control values in the retention and path B (reverse course) tests. On the Morris water maze task, the 5 mg/kg group required longer swimming time and distance to reach the goal. In the retest with the goal set on an opposite side, the swimming distance in the 5 mg/kg group was as long as the value in the original test. The radial eight‐arm maze test detected fewer correct choices in both MNU groups, which showed different responses on this task. The brain weights in the 3 and 5 mg/kg groups were approximately 80 and 60% of the control value, respectively. The cerebral cortex weights were 77 and 50% of the control value, and the hippocampus weights were 78 and 51%. Among the four maze tests, only the radial eight‐arm maze test could detect the effect of both doses of MNU. This shows that the method has the highest sensitivity to spatial learning defect in MNU‐induced microcephalic rats. © 1994 Wiley‐Liss, Inc.
Effects of the biguanide class of oral hypoglycemic agents on mouse embryogenesis
Authors: Denno Kelly M. , Sadler Thomas W.
Published: June 2005

The incidence of birth defects among offspring of mothers with non–insulin dependent diabetes mellitus (NIDDM) is 2–3–fold higher than among infants of non diabetics. Since mothers with NIDDM are frequently given oral hypoglycemic agents, including sulphonylureas and biguanides, to control their disease and since these agents have been associated with the occurrence of congenital malformations in humans and animals, the embryotoxic effects of the most commonly employed biguanides, metformin and phenformin, were evaluated in whole embryo culture. Neurulating mouse embryos were exposed to therapeutic concentrations (metformin 500–2,550 mg per day; phenformin 50–400 mg per day, respectively) of the compounds for 24–48 h. Concentrations of metformin in culture ranged from 0.15 to 1.8 mg/ml and phenformin from 2.5 × 10−5 to 0.4 mg/ml. Cultures were terminated and scored for gross morphological alterations and total protein content. Metformin produced no alterations in embryonic growth and no major malformations. Approximately 10% of all embryos exposed to metformin regardless of dose, exhibited open cranial neuropores after 24 h of culture. However, this anomaly appeared to represent a delay in closure as opposed to an overt defect, since no embryos exposed to the highest concentration of the drug and cultured for 48 h showed open neural tubes. In contrast, phenformin produced dose dependent changes in incidence of malformations, protein content, and embryolethality. Malformations included neural tube closure defects, craniofacial hypoplasia, and reduction in size of the first and second visceral arches. Doses above 0.1 mg/ml produced embryolethality and all embryos were killed at the 0.4 mg/ml concentration. Thus, of the two biguanides phenformin has a greater toxicity in whole embryo culture, suggesting that metformin may be safer for use during pregnancy. © 1994 Wiley‐Liss, Inc.
Effects of the class III Antiarrhythmic, Dofetilide (UK‐68,798) on the heart rate of midgestation rat embryos, in vitro
Authors: Spence Stanley G. , Vetter Christine , Hoe Chao‐Min
Published: June 2005

Gestation day 11 (GD11) and 14 (GD14) embryos were cultured for up to 4 hours in the presence of Dofetilide (0.01–0.50μg/ml), a potent Class III Antiarrhythmic which selectively inhibits the rapid component of the time dependent outward potassium current (IKr). Significant (P < 0.05) reductions in heart rate (HR) as measured over a 4 hour period were dose dependent and reversible. The sensitivity of the GD11 embryos was greater than GD14 embryos (14–64% decrease in HR vs. an 11–43% decrease in HR, respectively) at the same concentrations tested. These in vitro results support the hypothesis that the embryo‐lethality of Class III Antiarrhythmics observed in vivo may be a class effect of the IKr subtype potassium channel blockers. The data suggest a possible mechanism of embryotoxicity is to lower embryonic HR resulting in subsequent hypoxia and death. Dofetilide's effects on GD11 HR were partially reversible by the sequential addition of Isoproterenol or Theophylline. © 1994 Wiley‐Liss, Inc.
Effect of coniine on the developing chick embryo
Authors: Forsyth C. S. , Frank A. A. , Watrous B. J. , Bohn A. A.
Published: June 2005

Coniine, an alkaloid from Conium maculatum (poison hemlock), has been shown to be teratogenic in livestock. The major ter‐atogenic outcome is arthrogryposis, presumably due to nicotinic receptor blockade. However, coniine has failed to produce arthrogryposis in rats or mice and is only weakly teratogenic in rabbits. The purpose of this study was to evaluate and compare the effects of coniine and nicotine in the developing chick. Concentrations of coniine and nicotine sulfate were 0.015%, 0.03%, 0.075%, 0.15%, 0.75%, 1.5%, 3%, and 6% and 1%, 5%, and 10%, respectively. Both compounds caused deformations and lethality in a dose‐dependent manner. All concentrations of nicotine sulfate caused some lethality but a no effect level for coniine lethality was 0.75%. The deformations caused by both coniine and nicotine sulfate were excessive flexion or extension of one or more toes. No histopathological alterations or differences in bone formation were seen in the limbs or toes of any chicks from any group; however, extensive cranial hemorrhage occurred in all nicotine sulfate‐treated chicks. There was a statistically significant (P ≤ 0.01) decrease in movement in coniine and nicotine sulfate treated chicks as determined by ultrasound. Control chicks were in motion an average of 33.67% of the time, while coniine‐treated chicks were only moving 8.95% of a 5‐min interval, and no movement was observed for nicotine sulfate treated chicks. In summary, the chick embryo provides a reliable and simple experimental animal model of coniine‐induced arthrogryposis. Data from this model support a mechanism involving nicotinic receptor blockade with subsequent decreased fetal movement. © 1994 Wiley‐Liss, Inc.
Fetal anemia following maternal exposure to 5‐fluorouracil in the rat
Authors: Shuey Dana L. , Zucker Robert M. , Elstein Kenneth H. , Rogers John M.
Published: June 2005

Previous studies from our laboratory have shown that maternal 5‐fluorouracil (5‐FU) exposure on day 14 of gestation (GD14) in the rat results in dose‐dependent retardation of both cell cycle progression and growth of embryonic liver. At this developmental stage, hepatic erythropoiesis is the primary source of new circulating fetal erythrocytes. This study examined dose‐dependent hematological changes in the fetus after maternal 5‐FU exposure (0, 20, 30, 40 mg/kg on GD14) to assess 1) hematopoiesis as a potential target for 5‐FU developmental toxicity and 2) the role of the observed 5‐FU‐induced fetal anemia in adverse developmental outcome. Standard clinical hematological parameters, including hematocrit, hemoglobin content, and erythrocyte counts, were measured in fetal blood drawn by cardiac puncture. Dose‐related deficits were observed in all of these parameters within 48 hr of 5‐FU administration. Calculation of various red cell indices revealed a concomitant increase in mean cell volume and mean cell hemoglobin. These changes were preceded by depletion of hepatic precursor populations which was evident by 24 hr after maternal exposure to 30 or 40 mg/kg. At doses of 20 and 30 mg/kg there was full and moderate recovery, respectively, in these endpoints by 72 hr after dosing, but persistent deficits were observed at 40 mg/kg. Fluorescence microscopy of Hoechst‐stained fetal blood smears revealed that at both 48 and 72 hr after dosing, the proportion of nucleated yolk sac‐derived erythrocytes was increased relative to control. These data suggest that inhibition of proliferation of hepatic erythroid precursors by 5‐FU results in depletion of these populations and subsequent deficiency of liver‐derived reticulocytes in the fetal circulation, leading to fetal anemia. Since morphological changes are detectable within embryonal target tissues (e.g., hind limb buds) prior to the onset of significant hematological changes, fetal anemia is not involved in the pathogenesis of 5‐FU‐induced malformations. However, the persistence of hematological deficits at 40 mg/kg was correlated with fetal growth retardation during late gestation, suggesting that fetal anemia may be an important factor contributing to the developmental toxicity of 5‐FU. c 1994 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Teratogenesis by retinoic acid analogs positively correlates with elevation of retinoic acid receptor‐β2 mRNA levels in treated embryos
Authors: Jiang Heng , Iii Michael Gyda , Harnish Douglas C. , Chandraratna Roshantha A. , Soprano Kenneth J. , Kochhar D. M. , Soprano Dianne Robert
Published: June 2005

Retinoic acid (RA) plays an important role during normal embryogenesis, however high doses of RA are teratogenic. Retinoic acid receptor‐β2 (RAR‐β2) mRNA and protein levels were previously demonstrated to undergo rapid elevation in susceptible tissues after treatment with teratogenic doses of RA. In this report we compared the effects of a number of retinoids, which represent a wide variety of chemical structures and which differ in their teratogenic potencies, on RAR‐β2 mRNA levels in mouse embryos 6 hr after treatment. Retinoid treatments which result in a high incidence of limb defects elevated RAR‐ β2 mRNA levels similarly (10–14 fold in the limb buds, 4–8 fold in the head, and 2–4 fold in the remainder of the body). On the other hand, retinoid treatments which cause a low or no incidence of limb defects resulted in minor changes in RAR‐ β2 mRNA levels in each embryonic region. Therefore, a strong positive correlation was found between the elevation of RAR‐β2 mRNA levels and the retinoids which produce limb defects. This provides further evidence that an elevation of RAR‐β2 mRNA levels and subsequently protein levels, is an important event involved in mediating the effects of RA during dysmorphogenesis. © 1994 Wiley‐Liss, Inc.
Ebstein's malformation of the tricuspid valve: Genetic and environmental factors
Authors: Correa‐Villaseñor Adolfo , Ferencz Charlotte , Neill Catherine A. , David Wilson P. , Boughman Joanne A.
Published: June 2005

Ebstein's anomaly is a specific structural deformity of the tricuspid valve, and its rarity has hampered etiologic evaluation. Cases of Ebstein's anomaly registered in the Baltimore Washington Infant Study (BWIS), a regional case‐control study of cardiovascular malformations (CVM) in infancy, are reviewed. Between 1981 and 1989 a total of 4, 390 CVM cases, including 47 Ebstein cases, and 3, 572 controls were registered. The prevalencxe of Ebstein's anomaly was 5.2 per 100, 000 livebirths. Additional cardiac anomalies were present in 38. 3% of Ebstein cases. Non‐cardiac malformations were present in 19. 1% of Ebstein cases vs. 25.5% of other CVM, and 1.7% of controls. Case‐fatality by 1 year of age was 23. 4% in Ebstein cases, vs 18. 1% in other CVM. Interviews of parents of Ebstein cases, other CVM, and controls (n = 44, 3,335, and 3,572, respectively) elicited information on family history of malformations, maternal illnesses, reproductive history, therapeutic drugs, parental lifestyle, and environmental exposures during the periconceptional period. Case‐control analyses suggest genetic, reproductive, and environmental risk factors: twins [odds ratio (OR) 8.2, 95% confidence interval (CI) 2.6–25.3]; family history of CVM (OR 6.4, 95% CI 1.8–22.2); white race (OR 2.9 with non‐whites as reference, 95% CI 1.2–7.0); previous miscarriages (OR 2.0, 95% CI 1.2–3.3); maternal exposure to benzodiazepines (OR 3. 4, 95% CI 1.3–9.1); and varnishing (OR 3.4, 95% CI 1.3–9.1). Additional multicenter investigations are warranted to elucidate the role of genetic, reproductive, and environmental factors in the etiology of this anomaly. © 1994 Wiley‐Liss, Inc.
A fetus with sirenomelia, omphalocele, and meningomyelocele, but normal kidneys
Authors: McCoy M. Cathleen , Chescheir Nancy C. , Kuller Jeffrey A. , Altman Georgia C. , Flannagan Lisa M.
Published: June 2005

Sirenomelia, which has been reported for more than 450 years, is the most severe form of caudal dysplasia. This disorder is classically associated with agenesis or severe dysplasia of the Urinary tract.

A 27‐year‐old gravida 3 para 0020 presented at 19 weeks′ gestation with monoamniotic twins, one normal and one with sirenomelia. The pregnancy miscarried following invasive diagnostic testing. Autopsy confirmed the findings of sirenomelia, meningomyelocele, omphalocele, persistent cloaca, and two normal kidneys.

The abnormalities accompanying sirenomelia appear as a spectrum. The pathogenic theories of sirenomelia are reviewed in light of this case with normal kidneys. © 1994 Wiley‐Liss, Inc. © 1994 Wiley‐Liss, Inc.
Deaths associated with renal agenesis: A population‐based study of birth prevalence, case ascertainment, and etiologic heterogeneity
Authors: Cunniff Christopher , Kirby Russell S. , Senner John W. , Canino Carole , Brewster Marge A. , Butler Becky , Hassed Susan J. , Murphy Pam
Published: June 2005

We report on deaths associated with renal agenesis among 211,704 consecutive births. Sources included birth and death certificates and an active birth defects surveillance system. Medical review and classification of cases were performed for 1985–1990 events. Sixty‐one cases of renal agenesis were identified, and review of records was possible for 59 of the 61 cases. Of these 59 cases, 36 (61%) were confirmed, 5 (8%) were questionable, and 18 (31%) were incorrectly coded. The prevalence of confirmed cases is thus estimated at 17/100,000 births (14.2/100,000 births, excluding elective terminations and fetal deaths). Records incorrectly coded were most of ten those with multicystic dysplasia. Approximately one‐third of cases was found by the birth defects surveillance system alone, confirming the utility of this data source for prevalence estimates. Isolated renal agenesis accounted for 44% of confirmed cases; other diagnoses included VATER association (19%), unrecognized multiple malformation syndromes (17%), exstrophy of the cloaca sequence (14%), and chromosome disorders (6%). Based on these data, prevalence rates for ICD code 753.0 and death include overascertainment of cases from erroneous coding of multicystic dysplasia and underascertainment of cases with unilateral renal agenesis associated with other malformations. Population‐based ascertainment of cases by active surveillance methods and rigorous diagnostic coding standards are required to improve the accuracy of these rates. Targeted investigations of distinct subclassifications will be necessary to identify specific etiologic factors. © 1994 Wiley‐Liss, Inc.