We introduce the Embryology domain of TheScientificWorld and outline the scope and aims. We argue for an interdisciplinary approach to problems in develop-mental biology. Three areas are identified as being of particular relevance to this domain: evolutionary developmental biology, teratology, and descriptive or experimental embryology. (+info)
Regenerative medicine: stem cells and the science of monstrosity.
The nineteenth century science of teratology concerned itself with the study of malformations or "monstrosities", as they were then called. The first major contribution to the field was the work of Isidore Geoffrey Saint-Hilaire, Historie Generale et Particuliere des Anomalies de l'Organisation chez l'Homme et les Animaux, published in 1832, whose classifications formed the basis for the later experimental science of teratogeny, the art of reproducing monstrosities in animal embryos. In this article, I will argue that recent developments in the field of regenerative medicine can be situated in the tradition of teratological and teratogenic studies dating back to the nineteenth century. In particular, I will be interested in the historical link between studies in teratogenesis (the artificial production of teratomas) and stem cell research. Recent advances in stem cell research, I will suggest, return us to the questions that animated nineteenth century investigations into the nature of the monstrous or the anomalous. In the process, our most intuitive conceptions of "life itself" are undergoing a profound transformation. (+info)
Long-term effects of in utero exposure to cyclosporin A on renal function in the rabbit.
The number of pregnant women who receive cyclosporin A (CsA) after transplantation or for autoimmune disease has increased. CsA and its metabolites can cross the placental barrier and thus interfere with fetal development. It was shown previously that rabbits that were exposed in utero to 10 mg/kg per d CsA from the 14th to the 18th day of gestation presented a 25% nephron reduction. Thus, this study was conducted to assess the long-term systemic and renal effects of a CsA-induced nephron reduction. Twenty-two pregnant New Zealand white rabbits were randomly divided into two groups: Twelve received 10 mg/kg per d CsA from day 14 to day 18 of gestation, and 10 were used as controls. Rabbits that were born to these animals were evaluated at 4, 11, 18, and 35 wk of life. Pups that were exposed antenatally to CsA presented first a permanent nephron deficit; second, glomerular, tubular, and intrarenal hemodynamics dysfunction; third, enlarged kidneys with numerous tubular and glomerular lesions; and, fourth, an endothelin-dependent systemic hypertension that worsened with age. In utero exposure to CsA induced a nephron reduction that led to systemic hypertension and progressive chronic renal insufficiency in adulthood. A long-term clinical survey is mandatory in infants who are born to mothers who were treated with cyclosporin during pregnancy. (+info)
Applications of magnetic resonance microscopy.
Magnetic resonance imaging (MRI) has enjoyed enormous clinical success since the first demonstration of the method more than 30 years ago. An increasing number of pharmaceutical manufacturers seeking new biomarkers for assessing drug efficacy and toxicity are turning to MRI. A specific application of MRI promises to revolutionize pathology for the basic scientist in the same way MRI has forever altered the standard of care in the clinical domain. More specifically, this application is the use of magnetic resonance microscopy (MRM) in conjunction with new staining methodologies that now make MRM routinely available to the widest range of investigators. (+info)
L'Ecole de Nogent: the contributions of Etienne Wolff and Nicole Le Douarin.
We retrace here the foundation of the "Nogent School". What were its main scientific orientations? Two fields of research dominated Etienne Wolff's work: Experimental Teratology and Intersexuality. Nicole Le Douarin's work , in one sense, started with a remarkable tool which is the quail / chick marker system. She applied this system to the study of in vivo migration of cells during embryonic life, i.e.neural crest cells and lymphoid progenitors. This article revisits some of these fundamental aspects. (+info)
Developmental toxicology - an integral part of safety evaluation of new drugs.
The thalidomide tragedy stimulated an intense research in the etiology, prevention and treatment of congenital malformations. The Government requires that drugs and food additives be evaluated pre-clinically for toxicity, including developmental toxicity, before being marketed. The number of compounds which must be tested has increased dramatically with the continuous development of therapeutic, cosmetic and food additive chemicals. Such tests include: in vitro studies which can serve as efficient pre-screens to rank chemicals for further batteries of in vivo tests on pregnant animals. However, the safety of any drug would be determined only by a post-marketing epidemiological survey. Taking into account the altered susceptibility to different drugs in a pregnant individual, it could be said that administration of any drug during the first trimester is an experiment in human teratology. (+info)
Assessment of adolescent neurotoxicity: rationale and methodological considerations.
This introduction to the special issue of Neurotoxicology and Teratology on "Risk of neurobehavioral toxicity in adolescence" begins by broadly considering the ontogeny and phylogeny of adolescence, and the potential value of animal models of adolescence. Major findings from the emerging neuroscience of adolescence are then highlighted to establish the importance of studies of adolescent neurotoxicity. A variety of methodological issues that are of particular relevance to adolescent exposures are then discussed. These include consideration of pharmacokinetic factors, inclusion of other-aged comparison group(s), and issues involving timing, route of administration, and exposure-induced alterations in growth rate. Despite such methodological challenges, research to determine whether adolescence is a time of increased vulnerability (or greater resiliency) to specific drugs and environmental toxicants is progressing rapidly, as exemplified by the work presented in the articles of this special issue. (+info)
On models for binomial data with random numbers of trials.
A binomial outcome is a count s of the number of successes out of the total number of independent trials n=s+f, where f is a count of the failures. The n are random variables not fixed by design in many studies. Joint modeling of (s, f) can provide additional insight into the science and into the probability pi of success that cannot be directly incorporated by the logistic regression model. Observations where n= 0 are excluded from the binomial analysis yet may be important to understanding how pi is influenced by covariates. Correlation between s and f may exist and be of direct interest. We propose Bayesian multivariate Poisson models for the bivariate response (s, f), correlated through random effects. We extend our models to the analysis of longitudinal and multivariate longitudinal binomial outcomes. Our methodology was motivated by two disparate examples, one from teratology and one from an HIV tertiary intervention study. (+info)