bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of pulsing electromagnetic fields on the prenatal and postnatal development in mice and rats: In vivo and in vitro studies
Authors: Zusman Igor , Yaffe Perhija , Pinus Helena , Ornoy Asher 
Published: June 2005

AbstractElectromagnetic fields (EMF) might have various biological effects on the developing embryo. We studied the effects of pulsing electromagnetic fields (PEMF) on the in vitro development of preimplantation mouse embryos and of early somite rat embryos as well as on the in vivo development of rat embryos. We used PEMF at frequencies of 1, 20, 50, 70, and 100 Hz with a tension of 0.6 V/m. The embryos were exposed to PEMF throughout the experimental period. PEMF at frequencies of 20 and 50 Hz were embryotoxic, inhibiting over 50% of blastocysts from hatching and further development, all within 72 h of culture. PEMF at frequencies of 50 and 70 Hz induced 22% and 30% incidence of malformations in 10.5 day old rat embryos after 48 h in culture. The main malformations were absence of telencephalic, optic, and otic vesicles and of forelimb buds. In addition, retarded growth and development manifested by fewer somites, reduction in crown‐rump length, and retarded closure of the neural tube were found in many embryos. No significant pathological changes were found by TEM in PEMF‐exposed embryos. Disappearance of microvilli and collapse of apical parts of endodermal cells were observed by SEM in many yolk sacs of embryos exposed to 50 and 70 Hz PEMF. A slightly reduced litter average, a reduction or increase of weight, and a delay in eye opening was observed among offspring of pregnant rats exposed throughout pregnancy to PEMF at frequencies of 20, 50, and 100 Hz. No malformations were observed among these offspring. The mechanism of PEMF‐induced embryotoxicity and teratogenecity is unknown, as is the mechanism of the “protective effects” of the mother on the rat embryos exposed to PEMF in vivo.
Expression of a new mutation (Axd) causing axial defects in mice correlates with maternal phenotype and age
Authors: Essien Francine B. , Haviland Martha B. , Naidoff Alan E. 
Published: June 2005

AbstractA new autosomal mutation, Axd (axial defects), is described. Axd segregates in a simple Mendelian fashion, and it is dominant with incomplete penetrance and variable expressivity. The phenotype of Axd heterozygotes ranges from a variety of tail anomalies to visibly normal tails. Approximately 12% of neonates from curly‐tail (CT) F1 (Axd/ + ) × F1 (Axd/ +) matings exhibit open neural tube defects (NTD) in the lumbosacral region and 16% have curly tails. Mean litter sizes and resorption rates comparable to wild type indicate that homozygosity for Axd is not obligately lethal. Genetic background plays a major role in Axd expression. Strains such as BALB/cByJ allow the highest penetrance of the mutation in single dose (46%), whereas, in CF‐1 mice Axd is recessive. The tail phenotype of heterozygous Axd/ + dams, in part reflective of their genetic background, correlates with the incidence of NTD in F2 offspring: CT mothers produce significantly more neonates with frank NTD than normal tail mothers. At the one embryonic period examined for this study (D13/D14 post‐coitus), an 85% higher incidence of total axial defects is observed than among the F2 at birth. Unchanging litter size and the relative increase in phenotypically normal offspring by birth suggest that Axd acts by delaying posterior neural tube closure. One of the most significant findings in this study is that maternal age influences the survival of Axd embryos in utero. Axd/ + dams older than 8 months yield fewer mean implants, higher resorption rates, and fewer viable embryos with axial defects than do Axd/ + dams younger than 8 months. Axd is not allelic to nor linked to the Sp (splotch) gene which also affects neurulation.
Examination of the eyelid closure defect in trisomy 16 mice
Authors: Lipski David A. , Bersu Edward T. 
Published: June 2005

AbstractA characteristic feature of trisomy 16 mouse conceptuses is a failure of their eyelids to close. This defect was investigated by examining ocular development in serially sectioned heads of trisomy 16 and normal littermate fetuses from 10 to 18 gestational days. Other heads were examined by using scanning electron microscopy. Between 10 and 15 days, trisomy 16 ocular structures were delayed, but there was no striking abnormal morphology. At 16 days, when the eyelids were closed and fused in normal mice, trisomic eyes had a large cell mass near the inner canthus that protruded between the open lids. The mass was covered by bulbar conjunctiva and cells of the mass were continuous with developing corneal tissue. The mass was not present in the eyes of normal mice on any gestational day and was not present in trisomic eyes at 17 and 18 days, when the lids began to show varying degrees of closure. Based on its positioning at the inner canthus, the mass may represent a transient hyperplasia of the developing semilunar fold which physically impedes lid closure in the trisomic conceptuses. Previously, the defect has been attributed to the trisomy 16 conceptus's overall pattern of growth retardation and delayed development. Masses such as those seen in the trisomic eyes have not been observed in other murine lid‐gap defects that have been investigated. A second finding in this study is that trisomic eyes are positioned more superiorly in the head than normal eyes. This variation may be related to alterations in cranial base morphology that are associated with trisomy 16.
Risk factors for gastroschisis
Authors: Goldbaum Gary , Daling Janet , Milham Sam 
Published: June 2005

AbstractThe prevalence at birth of gastroschisis, a rare abnormality of the abdominal wall, appears to have increased over the past decade. To characterize risk factors that might explain this increase, birth certificates for Washington State residents were compared for 62 infants born with gastroschisis during the years 1984 to 1987 and 617 randomly selected unaffected infants matched for birth year. After simultaneously adjusting for 14 potential risk factors, 4 factors stood out. Infants born during January, February, or March were at greater risk than infants born in any other months (odds ratio 2.2, 95% confidence interval 1.1, 4.1). Mothers less than 25 years old were at greater risk than mothers 25 years and older, with the highest risk to mothers less than 20 years old (odds ratio 4.1, 95% confidence interval 1.4, 12.0). Women who smoked during pregnancy were at greater risk than women who did not smoke (odds ratio 2.0, 95% confidence interval 1.03, 3.8). Finally, mothers receiving inadequate prenatal care were at greater risk than mothers receiving adequate prenatal care (odds ratio 2.1, 95% confidence interval 0.99, 4.6). Unidentified behavioral and environmental exposures may explain the associations with month of birth, maternal age, and prenatal care. However, smoking during pregnancy is a plausible risk factor that should be examined further as an explanation of the apparently increasing prevalence at birth of gastroschisis in developed nations.
Evaluation of drug intake during pregnancy in the Hungarian case‐control surveillance of congenital anomalies
Authors: Czeizel Andrew , Rácz János 
Published: June 2005

AbstractThe data of the Hungarian Case‐Control Surveillance of Congenital Anomalies, 1980–1987, were evaluated concerning drug intake during pregnancy in 10,698 index patients, 21,546 negative controls, and 828 positive controls (Down syndrome). Excluding pregnancy supplements, the proportion of no drug use was about 30% and the mean number of drugs used was 2.0 in the negative control group. These figures did not differ significantly from data of study and positive control groups. The analysis of most commonly used drugs indicated an extremely high proportion of hormonal support therapy. The teratogenic effect of several human teratogenic drugs was confirmed. However, their use is relatively rare and their attributable risk within the etiology of congenital anomalies is low, at about 0.3–1.0%. At present the teratogenic risk of drugs in humans is exaggerated and it has several unfortunate consequences: negligence in necessary drug use, unnecessary anxiety in pregnant women, and termination of planned pregnancies without any reasonable cause.
Lethal and teratogenic effects after exposure to X‐rays at various times of early murine gestation
Authors: Müller W.‐U. , Streffer C. 
Published: June 2005

AbstractVarious well‐defined stages during completion of the second meiotic division and early organogenesis of mouse embryos were X‐irradiated with doses of 1–4 Gy (100–400 rad). The major risk was prenatal mortality with radiation sensitivity changing markedly with dependence on the developmental stage irradiated; in the case of day 1 even within hours. The surviving fetuses did show a significantly enhanced frequency of malformations on day 19 of gestation (mostly gastroschisis and some exencephalies). This was true for all stages between days 1 and 8; only sensitivity again changed considerably. The radiation doses used in this study are markedly higher than doses that can be expected from radiation diagnostics, but exposure is in a range comparable to doses that can occur in radiation therapy (e.g., Morbus Hodgkin).
A decade of rabbit fertility data: Study of historical control animals
Authors: Feussner Elizabeth L. , Lightkep Gerald E. , Hennesy Rosemary A. , Hoberman Alan M. , Christian Mildred S. 
Published: June 2005

AbstractReproductive data for 1795 artificially inseminated Hra: (NZW)SPF control rabbits in 93 developmental toxicity studies conducted from 1980 through 1989 were summarized. Data were obtained during terminal Caesarean‐sectioning procedures performed on animals which survived to day 29 of gestation and during postmortem evaluation of does which aborted, delivered prematurely, or were found dead. Significant seasonal variation was not observed. Average pregnancy rate, percentage of rabbits that aborted, and percentage of rabbits that delivered prematurely throughout the decade were 86, 2.0, and 1.6%, respectively. Average numbers of corpora lutea, implantations, live fetuses, dead fetuses, early resorptions, and late resorptions for each doe that survived to scheduled termination were 10.8, 7.8, 7.1, 0.02, 0.49, and 0.15, respectively. The various vehicles used, routes of administration, and a variety of maternal and paternal factors were compared with the fertility data, and no correlations were observed. Rabbits that aborted earlier in gestation had fewer implantations than does which aborted late or delivered prematurely. Does which resorbed 100% of their conceptuses had fewer corpora lutea and implantations when compared with rabbits in the remainder of the population. Rabbits pregnant at scheduled termination which had a low number of corpora lutea or implantation sites had higher than expected pre‐ and postimplantation losses relative to the population as a whole. Does with a high number of corpora lutea had significantly higher preimplantation loss relative to the general population. This may indicate the presence of a “ceiling value” for the number of ova that can become fertilized and/or implant when the ovulation rate is high and which probably varies according to strain as well as a number of factors related to the individual rabbit. Based upon the results of this study and the work of a previous author, a minimum of four corpora lutea may be necessary for the successful maintenance of pregnancy in the New Zealand white rabbit. The minimum number of corpora lutea required may be strain dependent and may bear a relationship to the normal litter size of the strain. © 1992 Wiley‐Liss, Inc.
Developmental toxicity study in rats treated with the anticonvulsant, ralitoline
Authors: Dostal Lori A. , Anderson John A. 
Published: June 2005

AbstractThe developmental toxicity of the anticonvulsant compound, ralitoline, was investigated in Sprague–Dawley rats administered oral doses of 0, 15, 60, 120, 180, or 240 mg/kg on days 6 through 15 of gestation. An untreated control group and a vehicle control group pair‐fed to the high dose group were included. Maternal and fetal parameters were evaluated on day 21 of gestation. Fetuses were examined for external, visceral, and skeletal malformations and variations. Maternal death occurred at 180 and 240 mg/kg. Dose‐dependent decreases in body weight, food consumption, and water consumption were observed at 60 mg/kg and above. Body weight gain during treatment was similar in the pair‐fed and 240 mg/kg groups. Dose‐related CNS signs (hypoactivity, ataxia, prostration, and/or convulsions) were observed at 60 mg/kg and above. Decreased numbers of live fetuses and increased postimplantation loss were observed in a dose‐related manner at 120, 180, and 240 mg/kg while no changes occurred in pair‐fed controls. Fetal body weights and placental weights were decreased in pair‐fed controls and in the 120, 180, and 240 mg/kg groups. The percent fetuses per litter, and the percent litters with external/visceral malformations, were significantly increased at 120, 180, and 240 mg/kg compared with vehicle and pair‐fed controls. Dose‐related increases in cardiovascular malformations, specifically of the aortic arch (interrupted, stenotic, extra vessel), were apparent at 120 mg/kg and above. The incidence of skeletal variations was increased at 120 mg/kg and above. This study demonstrates the developmental toxicity, including teratogenicity, of the anticonvulsant compound, ralitoline, in rats at maternally toxic doses, and demonstrates a lack of developmental toxicity at lower doses which were less maternally toxic. © 1995 Wiley‐Liss, Inc.
Increased risk for transverse digital deficiency after chorionic villus sampling: Results of the United States multistate case‐control study, 1988–1992
Authors: Olney Richard S. , Khoury Muin J. , Alo Celan J. , Costa Pamela , Edmonds Larry D. , Flood Timothy J. , Harris John A. , Howe Holly L. , Moore Cynthia A. , Olsen Carolyn L. , Panny Susan R. , Shaw Gary M. 
Published: June 2005

AbstractAlthough numerous infants have been reported with transverse limb deficiencies after their mothers had undergone chorionic villus sampling (CVS), it has been unclear whether the procedure caused these defects. We report of the first multistate case‐control study to assess and quantify the risk for specific limb deficiencies associated with CVS. Case subjects were 131 infants with nonsyndromic limb deficiency ascertained from 7 population‐based birth defect surveillance programs, and born from 1988–1992 to mothers 34 years of age or older. Control subjects were 131 infants with other birth defects. We ascertained exposure to CVS from medical records and maternal and physician questionnaires. We assessed rates and timing of exposure to CVS, and estimated relative and absolute risks for anatomic subtypes of limb deficiency. The odds ratio for all types of limb deficiency after CVS from 8–12 weeks′ gestation was 1.7 (95% confidence interval, 0.4–6.3). For specific anatomic subtypes, the strongest association was for transverse digital deficiency (odds ratio = 6.4; increased 95% confidence interval, 1.1–38.6). The risk for transverse digital deficiency with earlier gestational exposure (P < 0.01 for trend). We estimated that 1 per the absolute risk for transverse digital deficiency in infants after CVS was 2,900 births (0.03%). Exposure to CVS was associated with a sixfold increase in risk by for transverse digital deficiency. The causality of this association is supported of its strength, specificity, biologic plausibility, and consistency with the results limb previous studies. Although some centers already inform patients about risk for limb deficiency, this study quantifies the magnitude of risk associated with CVS from 8–12 weeks′ gestation. © 1995 Wiley‐Liss, Inc.
Flow cytometric detection of abnormal fetal erythropoiesis: Application to 5‐fluorouracil‐induced anemia
Authors: Zucker Robert M. , Elstein Kenneth H. , Shuey Dana L. , Rogers John M. 
Published: June 2005

AbstractWe sought to determine whether flow cytometric analysis of circulating fetal blood cells could be used to rapidly detect perturbations of fetal erythropoiesis. In addition, we wanted to determine whether this approach would allow sample collection by exsanguination instead of fetal cardiac puncture, a difficult technique used to prevent contamination of samples with maternal erythrocytes. To monitor fetal erythropoiesis from gestational day (GD) 14–20, we analyzed the cell size, RNA content, and percentage of circulating liver‐derived reticulocytes relative to yolk‐sac‐derived erythroblast. As a model toxicant, we choose 5‐fluorouracil (5‐FU), since we previously observed that maternal administration at 20–40 mg/kg on gestational day (GD) 14 produced fetal anemia on GD 16–17, as evidenced by dose‐dependent decreases in the cell counts, hematocrit, and hemoglobin content of fetal blood obtained by cardiac puncture. We report herein that 48 hr after maternal 5‐FU administration, both cardiac and peripheral blood samples exhibited a dose‐dependent decrease in the relative percentage of reticulocytes, indicating a reduced rate of reticulocyte release from the fetal liver. Moreover, at 30 and 40 mg/kg, reticulocytes exhibited increased size and reduced RNA content on GD 16, but elevated RNA content (indicative of premature release) by GD 18. These data suggest that 5‐FU inhibits both erythroid cell proliferation and RNA synthesis reversibly, resulting in an anemia that triggers compensatory release of immature reticulocytes. Thus, by using flow cytometry to analyze fetal blood, we were able to detect and characterize 5‐FU‐induced perturbations of fetal erythropoiesis. In so doing, flow cytometry afforded the advantages of rapid determination of individual cell type, size, and RNA content, and the ability to exclude contaminating maternal erythrocytes from analysis, thereby eliminating the need to acquire samples through the time‐consuming technique of fetal cardiac puncture. © 1995 Wiley‐Liss, Inc.
Social interactions and solitary behaviors in a pair of captive sand cats (Felis margarita)
Authors: Bennett Sarah Williams , Mellen Jill D. 
Published: June 2005

AbstractThis study examined the behavior and activity of two captive sand cats at the Washington Park Zoo in Portland, Oregon. Sex differences in behavior were examined and the direction and frequency of social interactions were determined. An attempt was made to determine behavioral signs of estrus. A scan sampling data collection technique was used to find the percentage of time spent by each cat in each behavior. Simultaneously, the frequency of social behaviors was recorded. The cats spent the greatest percentage of their time pacing and resting; social interactions occurred very infrequently. The only significant sex difference in behavior was that the male marked and urinated/defecated more than did the female. Temporal distribution in the usage of the enclosure was examined. It was found that when one cat was active, the other tended to be inactive. No overt behavioral signs of estrus were evident other than the actual observance of copulation. However, the percentage of time spent in each behavior was examined when the female was assumed to be in estrus (days when copulation was observed) versus nonestrous periods. The female was found to pace and locomote significantly more during estrous periods.
Protein variation, fitness, and captive propagation
Authors: Hedrick Philip W. , Brussard Peter F. , Allendorf Fred W. , Beardmore John A. , Orzack Steven 
Published: June 2005

AbstractWe examine the possibility of utilizing protein variation (allozymes) as a tool in the preservation and breeding of endangered and captive species. We believe that allozymes provide estimates of the relative amounts of genetic variation within and among populations. However, because of the difficulties encountered in evaluating both heterozygosity and fitness, we conclude that estimates of individual heterozygosity derived from allozyme studies are poor criteria for selecting individuals for breeding in captive propagation schemes. Furthermore, breeding plans designed to maintain rare allozymes in captive populations represent an unwise strategy for the propagation of most rare and endangered animal species. We believe that successful reintroduction is most likely when genetic variation is preserved as found in natural populations.
Ancestry of alleles and extinction of genes in populations with defined pedigrees
Authors: Thompson E. A. 
Published: June 2005

AbstractThe paper presents, without mathematical formalities, two computational approaches to the analysis of pedigrees. One provides a method for inferring the ancestry of rare alleles observed in a population. The other provides the probabilities that specified combinations of founder genes survive to this current population. The emphasis in both approaches is upon the importance of joint probabilities. If some founder genes survive, others have smaller probability of doing so also. If an allele descends from a given founder to a current individual, it is likely to appear also in individuals sharing the same lines of descent.
Genetic drift and the loss of alleles versus heterozygosity
Authors: Allendorf Fred W. 
Published: June 2005

AbstractMost studies of the loss of genetic variation caused by bottlenecks in population size have used heterozygosity as a measure of genetic variation. In this paper, I compare the effects of bottlenecks on the loss of alleles, as well as the reduction in heterozygosity. Population bottlenecks of short duration will have little effect on heterozygosity but are expected to reduce severely the number of alleles present. Heterozygosity provides a good measure of the capability of a population to respond to selection immediately following a bottleneck. However, the number of alleles remaining is important for the long‐term response to selection and survival of populations and species.
Genetic variability, inbreeding, and reproductive performance in standardbred horses
Authors: Cothran E. Gus , MacCluer Jean W. , Weitkamp Lowell R. , Guttormsen Sally A. 
Published: June 2005

AbstractThe relationships between electrophoretically determined genic variability, inbreeding, and reproductive success have been examined for Standardbred horses. There was a statistically significant relationship between foaling and/or conception rate and probability of offspring heterozygosity in Standardbred pacing horses. This relationship could not be explained by inbreeding depression. Inbreeding, at the level observed in Standardbreds, had little or no effect upon reproductive success. Additionally, there was no relationship between the inbreeding coefficient and the observed level of genetic heterozygosity. The results of these analyses suggest a program of a low rate of inbreeding combined with selection for characteristics associated with overall vigor as a management strategy for captive populations.