Yeung Sau-Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 139-172). / Abstracts in English and Chinese. / Title page --- p.i / Acknowledgements --- p.ii / Table of Content --- p.iv / List of Figures --- p.viii / List of Graphs --- p.x / List of Tables --- p.xi / Abbreviations --- p.xiv / Abstract --- p.xv / Chinese Abstract --- p.xvii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Diabetes Mellitus --- p.2 / Chapter 1.1.1 --- Type 1 diabetes mellitus --- p.3 / Chapter 1.1.2 --- Type 2 diabetes mellitus --- p.5 / Chapter 1.1.3 --- Maturity onset diabetes of the young (MODY) --- p.6 / Chapter 1.1.4 --- Gestational diabetes --- p.7 / Chapter 1.2 --- Effect of Diabetes on Pregnancy --- p.9 / Chapter 1.3 --- Suggested Causes of Diabetic Embryopathy --- p.10 / Chapter 1.3.1 --- Glucose --- p.10 / Chapter 1.3.2 --- Ketone bodies --- p.11 / Chapter 1.3.3 --- Somatomedin inhibitors --- p.12 / Chapter 1.3.4 --- TNF-α --- p.12 / Chapter 1.3.5 --- Oxidative stress --- p.13 / Chapter 1.4 --- Animal Model of Diabetes --- p.15 / Chapter 1.4.1 --- Chemically-induced --- p.15 / Chapter 1.4.2 --- Mutants --- p.17 / Chapter 1.5 --- Gene-teratogen Interaction under Diabetic Pregnancy --- p.19 / Chapter 1.6 --- Strategy of the Thesis --- p.21 / Chapter Chapter 2 --- General Materials and Methods --- p.24 / Chapter 2.1 --- Mouse Maintenance and Mating Method --- p.25 / Chapter 2.2 --- Induction of Diabetes --- p.25 / Chapter 2.3 --- Preparation of All-trans Retinoic Acid --- p.26 / Chapter 2.4 --- Dissection of Embryos --- p.26 / Chapter 2.5 --- DNA Extraction from Yolk Sac for Genotyping --- p.27 / Chapter 2.6 --- Genotyping of Embryos --- p.28 / Chapter 2.7 --- Preparation of RNA Probes for In Situ Hybridization --- p.29 / Chapter 2.7.1 --- Mini-scale preparation of plasmid DNA --- p.29 / Chapter 2.7.2 --- Linearization of plasmid DNA --- p.30 / Chapter 2.7.3 --- In vitro transcription --- p.31 / Chapter 2.8 --- Whole Mount In Situ Hybridization --- p.33 / Chapter 2.8.1 --- Fixation and dehydration of embryos --- p.33 / Chapter 2.8.2 --- Hybridization --- p.33 / Chapter 2.8.3 --- Post-hybridization wash --- p.34 / Chapter 2.8.4 --- Antibody wash and color development --- p.35 / Chapter 2.8.5 --- Embryo powder preparation --- p.36 / Chapter 2.8.6 --- Pre-absorption of antibody --- p.35 / Chapter 2.9 --- Whole Mount TUNEL Staining --- p.36 / Chapter Chapter 3 --- "Maternal Diabetes, Sp2H and RA Interaction" --- p.39 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.1.1 --- Neural tube defects --- p.41 / Chapter 3.1.2 --- Retinoic acid as environmental factor --- p.41 / Chapter 3.1.3 --- Sp2H as genetic factor --- p.44 / Chapter 3.1.4 --- Experimental design of this chapter --- p.46 / Chapter 3.2 --- Material and Methods --- p.47 / Chapter 3.2.1 --- Sp2H mice --- p.47 / Chapter 3.2.2 --- Mating and RA injection protocol --- p.47 / Chapter 3.2.3 --- Dissection of fetuses and analysis of neural tube development --- p.48 / Chapter 3.3 --- Results --- p.49 / Chapter 3.3.1 --- Maternal diabetes alone --- p.50 / Chapter 3.3.2 --- Sp2H mutation alone --- p.51 / Chapter 3.3.3 --- RA alone --- p.52 / Chapter 3.3.4 --- Maternal diabetes and RA interaction --- p.53 / Chapter 3.3.5 --- Sp2H mutation and RA interaction --- p.55 / Chapter 3.3.6 --- Sp2H mutation and maternal diabetes interaction --- p.57 / Chapter 3.3.7 --- "Maternal diabetes, Sp2H mutation and RA interaction" --- p.59 / Chapter 3.4 --- Discussion --- p.62 / Chapter 3.4.1 --- Maternal diabetes alone does not cause neural tube defects --- p.62 / Chapter 3.4.2 --- RA induces neural tube defects --- p.63 / Chapter 3.4.3 --- Interaction of maternal diabetes with RA in increasing the susceptibility to neural tube defects --- p.64 / Chapter 3.4.4 --- Embryos with Sp2H allele show increased susceptibility to neural tube defects when triggered by maternal diabetes and RA --- p.67 / Chapter Chapter 4 --- Molecular and Cellular Bases of Interaction --- p.71 / Chapter 4.1 --- Introduction --- p.72 / Chapter 4.1.1 --- Mechanism of diabetic embryopathy --- p.72 / Chapter 4.1.2 --- Mechanism of Sp2H mutation in development of neural tube defects --- p.74 / Chapter 4.1.3 --- Mechanism of RA teratogenicity --- p.75 / Chapter 4.1.4 --- "Possible common pathways shared by maternal diabetes, RA and Sp2H mutation" --- p.76 / Chapter 4.1.5 --- Experimental design of this chapter --- p.78 / Chapter 4.2 --- Materials and Methods --- p.80 / Chapter 4.2.1 --- Sample collection for studying Pax3 expression in Sp2H/+ And +/+ embryos in response to maternal diabetes or RA by whole mount in situ hybridization --- p.80 / Chapter 4.2.2 --- "Sample collection for studying the level of apoptosis in response to the interaction of maternal diabetes, Sp2H mutation and RA by whole mount TUNEL staining" --- p.82 / Chapter 4.3 --- Results --- p.86 / Chapter 4.3.1 --- Expression levels of Pax3 mRNA detected by whole mount in situ hybridization / Chapter 4.3.1.1 --- Expression of Pax3 in Sp2H/+/- and +/+ embryos --- p.86 / Chapter 4.3.1.2 --- Effect of maternal diabetes on Pax3 expression in Sp2H/+ and +/+ embryos --- p.87 / Chapter 4.3.1.3 --- Effect of RA on Pax3 expression in Sp2H /+ and +/+ embryos --- p.88 / Chapter 4.3.2 --- Level of apoptosis detected by whole mount TUNEL --- p.89 / Chapter 4.3.2.1 --- Effect of Sp2H allele on apoptosis --- p.94 / Chapter 4.3.2.2 --- Effect of maternal diabetes on apoptosis in Sp2H/+ and +/+ embryos --- p.95 / Chapter 4.3.2.3 --- Effect of RA on apoptosis in Sp2H/+ and +/+ embryos --- p.96 / Chapter 4.3.2.4 --- Effect of maternal diabetes and RA on apoptosis in Sp2H/+ and +/+ embryos --- p.97 / Chapter 4.4 --- Discussion --- p.99 / Chapter 4.4.1 --- Underexpression of Pax3 and increases in apoptosis under maternal diabetes --- p.99 / Chapter 4.4.2 --- "RA does not down regulate Pαx3, but increases apoptosis" --- p.102 / Chapter 4.4.3 --- Interaction of maternal diabetes and RA in increasing apoptosis --- p.104 / Chapter Chapter 5 --- "Maternal Diabetes, NOD and RA Interaction" --- p.108 / Chapter 5.1 --- Introduction --- p.109 / Chapter 5.1.1 --- Diabetic embryopathy in NOD mice --- p.109 / Chapter 5.1.2 --- Experimental design of this chapter --- p.110 / Chapter 5.2 --- Materials and Methods --- p.112 / Chapter 5.2.1 --- NOD mice --- p.112 / Chapter 5.2.2 --- Mating and RA Injection Protocol --- p.112 / Chapter 5.2.3 --- Sample Collection for the Study of Pax3 Expression --- p.113 / Chapter 5.3 --- Results --- p.115 / Chapter 5.3.1 --- Maternal diabetic alone --- p.116 / Chapter 5.3.2 --- NOD mutation alone --- p.117 / Chapter 5.3.3 --- RA alone --- p.118 / Chapter 5.3.4 --- Maternal diabetes and RA interaction --- p.119 / Chapter 5.3.5 --- NOD mutation and RA interaction --- p.121 / Chapter 5.3.6 --- NOD mutation and maternal diabetes interaction --- p.123 / Chapter 5.3.7 --- "Maternal diabetes, NOD mutation and RA interaction" --- p.125 / Chapter 5.3.8 --- Expression of Pax3 in embryos with different copies of NOD alleles --- p.128 / Chapter 5.4 --- Discussion --- p.130 / Chapter 5.4.1 --- Maternal diabetes interacts with NOD mutation to increase susceptibility to neural tube defects --- p.130 / Chapter 5.4.2 --- Interaction of maternal diabetes with NOD mutation is greatly exacerbated when exposed to RA --- p.131 / Chapter 5.4.3 --- Pax3 is not involved in the interaction --- p.133 / Chapter Chapter 6 --- Conclusion and Future Perspectives --- p.134 / References --- p.139 / Figures / Graphs

Neural tube defects (NTDs) are malformations affecting about 2.6/1000 births worldwide, and 1/1000 in the United States. Their etiology remains unknown, and is likely due to interaction of genetic susceptibility factors with environmental exposure. Of the many environmental agents considered to potentially contribute to NTD risk, arsenic is one that is surrounded in controversy. We have developed a model system utilizing maternal intraperitoneal (I.P.) exposure on E7.5 and E8.5 to As 9.6 mg/kg (as sodium arsenate) in a normal inbred mouse strain, LM/Bc/Fnn, that is sensitive to arsenate-induced exencephaly. We investigated arsenate induced gene expression changes using DNA microarrays of embryonic anterior neural tube tissue, as well as monitoring of metabolic function in conjunction with the administration of select compounds to rescue the normal phenotype. Finally, to address questions concerning the importance of route of administration and potential maternal toxicity, a teratology study was performed using three arsenate doses administered orally. Regarding the gene expression study, we identified several candidate genes and ontology groups that may be responsible for arsenate’s teratogenicity. Genes include: engrailed 1 (En-1), platelet derived growth factor receptor alpha (Pdgfrα) and ephrinA7 (EphA7). Gene ontology groups identified include oxidative phosphorylation, redox response, and regulation of I-kappaB kinase/NF-kappaB cascade. Acute arsenate exposure induced disruption of mitochondrial function and dependent glucose homeostasis: subsequent hyperglycemia was teratogenic. Maternal treatment with insulin or n-acetyl cysteine, an antioxidant and precursor of glutathione synthesis, proved highly successful in rescuing both the normal phenotype, and to differing degree, the maternal hyperglycemia. Maternal oral arsenate administration also resulted in exencephaly, with exposed embryos exhibiting a positive linear trend with arsenate dosage. There were also linear trends in the relationships between arsenate dose and anomalies involving several components of the axial skeleton: the vertebrae and calvarium. There was no evidence of maternal toxicity as shown by lack of differences in maternal body weight gain, liver, and kidney weights. In conclusion, maternal arsenate exposure (regardless of exposure route) was teratogenic in our model, primarily causing NTDs. Responsible mechanisms may involve disruption of redox and glucose homeostasis as well as expression of established NTD candidate genes.

Obesity in pregnancy has been associated with an elevated risk for neural tube defects, though it is unknown if this is linked to a lower folate status in obese women. Studies have identified a reduced folate status among obese women even after controlling for folate intake. Thus, it is possible that folic acid pharmacokinetics are altered in the obese body. In this study, we compared the pharmacokinetics of folic acid in obese and non-obese women of childbearing age, following administration of a weight-adjusted dose. Area under the concentration-time curve was found to be significantly higher in the obese group, with the dose per kilogram lean body weight most strongly predicting systemic exposure. Estimation of the daily dose required to achieve protective blood concentrations did not identify a need to change supplementation recommendations for obese women. Accordingly, current guidelines appear to suggest adequate doses for obese women of childbearing age.

Obesity in pregnancy has been associated with an elevated risk for neural tube defects, though it is unknown if this is linked to a lower folate status in obese women. Studies have identified a reduced folate status among obese women even after controlling for folate intake. Thus, it is possible that folic acid pharmacokinetics are altered in the obese body. In this study, we compared the pharmacokinetics of folic acid in obese and non-obese women of childbearing age, following administration of a weight-adjusted dose. Area under the concentration-time curve was found to be significantly higher in the obese group, with the dose per kilogram lean body weight most strongly predicting systemic exposure. Estimation of the daily dose required to achieve protective blood concentrations did not identify a need to change supplementation recommendations for obese women. Accordingly, current guidelines appear to suggest adequate doses for obese women of childbearing age.

Neural tube defects (NTDs) are malformations affecting about 2.6/1000 births worldwide, and 1/1000 in the United States. Their etiology remains unknown, and is likely due to interaction of genetic susceptibility factors with environmental exposure. Of the many environmental agents considered to potentially contribute to NTD risk, arsenic is one that is surrounded in controversy. We have developed a model system utilizing maternal intraperitoneal (I.P.) exposure on E7.5 and E8.5 to As 9.6 mg/kg (as sodium arsenate) in a normal inbred mouse strain, LM/Bc/Fnn, that is sensitive to arsenate-induced exencephaly. We investigated arsenate induced gene expression changes using DNA microarrays of embryonic anterior neural tube tissue, as well as monitoring of metabolic function in conjunction with the administration of select compounds to rescue the normal phenotype. Finally, to address questions concerning the importance of route of administration and potential maternal toxicity, a teratology study was performed using three arsenate doses administered orally. Regarding the gene expression study, we identified several candidate genes and ontology groups that may be responsible for arsenate’s teratogenicity. Genes include: engrailed 1 (En-1), platelet derived growth factor receptor alpha (Pdgfrα) and ephrinA7 (EphA7). Gene ontology groups identified include oxidative phosphorylation, redox response, and regulation of I-kappaB kinase/NF-kappaB cascade. Acute arsenate exposure induced disruption of mitochondrial function and dependent glucose homeostasis: subsequent hyperglycemia was teratogenic. Maternal treatment with insulin or n-acetyl cysteine, an antioxidant and precursor of glutathione synthesis, proved highly successful in rescuing both the normal phenotype, and to differing degree, the maternal hyperglycemia. Maternal oral arsenate administration also resulted in exencephaly, with exposed embryos exhibiting a positive linear trend with arsenate dosage. There were also linear trends in the relationships between arsenate dose and anomalies involving several components of the axial skeleton: the vertebrae and calvarium. There was no evidence of maternal toxicity as shown by lack of differences in maternal body weight gain, liver, and kidney weights. In conclusion, maternal arsenate exposure (regardless of exposure route) was teratogenic in our model, primarily causing NTDs. Responsible mechanisms may involve disruption of redox and glucose homeostasis as well as expression of established NTD candidate genes.

Thesis (M.S.)--Eastern Illinois University, 2004. / Includes bibliographical references (leaves 49-54).

Neural Tube Defects (NTDs) are a group of common congenital malformations that result from incomplete neural tube closure leading to abnormalities of the brain and/or spinal cord. Unfortunately, their etiology remains unknown, probably due to complex multifactorial interactions. The protective effect of dietary folates in preventing NTDs is well known, but this beneficial effect is limited to the 60 to 70% of cases; leaving 30% of the population without any known option for improving pregnancy outcomes. The mechanism by which folates rescue NTD-affected embryos is poorly understood, but the ability of folate supplementation to overcome a significant percentage of NTDs and the critical role of 5-methyltetrahydrofolate in the remethylation of homocysteine (Hcy) to methionine in the placenta suggests that folate binding and/or transport might play a critical role during development. We hypothesized that maternal autoantibodies (AB) targeting placental folate receptor alpha (FRα) are blocking the receptor and limiting the ability of the FRα to bind folates, reducing intraembryonic folate levels. Furthermore, we hypothesized that AB binding to other relevant proteins required for trophoblastic growth and placentation can be involved in activating pathologic inflammatory pathways that can result in suboptimal uptake of nutrients and contribute to an abnormal closure of the neural tube. We developed a high throughput ELISA to evaluate whether mothers experiencing pregnancies complicated with NTDs are more likely to have placental AB to FRα than are mothers experiencing normal pregnancies. We optimized and simplified a protocol for AB elution from placental tissues and determined whether these antibodies were blocking the FRα from binding with available folates. Although anti-FRα IgG antibodies were not associated to the blocking activity in this study, we found that the blocking activity was higher in the placentas from NTD-affected pregnancies compared to controls, that FRα IgM antibodies are most likely the type of antibody produced during gestation that is most relevant to the blocking activity and that it is unlikely that autoimmunity against other developmental proteins associated with NTDs is generating the NTDs. / text

The splotch (sp) mutation has been identified as a mutation in the paired box gene, Pax-3. Heterozygous mice carrying this mutation are phenotypically normal, with the exception of a white spot on their bellies. Homozygous embryos do not live to birth, and suffer from a wide range of developmental defects, all of which result from delayed neural tube closure, or inadequate neural crest cell migration. Most notably, homozygotes have an increased rate of spina bifida with or without exencephaly. Retinoic acid (RA), which has been shown to be very important in the development of a number of systems, was shown to cause a selective mortality of the homozygous splotch embryos when administered maternally at day 9 p.c. (Moase and Trasler, 1987). Since cellular retinoic acid binding protein (CRABP) is localized to the tissues which are affected by both the splotch gene, and retinoic acid teratogenesis, its expression patterns in the developing splotch embryo were examined. It was found that the distribution of CRABP mRNA is normal, but its expression levels are excessive in splotch homozygous day 9 mouse embryos.

No description available.

Thesis (M.P.H.)--Georgia State University, 2007. / Title from file title page. Russ Toal, committee chair; Catherine McCarroll, Joseph Mulinare, committee members. Electronic text (83 p. : ill.) : digital, PDF file. Description based on contents viewed Jan 8, 2008. Includes bibliographical references (p. 79-83).