Indiana University-Purdue University Indianapolis (IUPUI) / MCTP2 (multiple C2 domain transmembrane containing protein 2) encodes a protein with poorly understood roles in lipid metabolism and lipid droplet biogenesis. Genetic studies previously identified variations in MCTP2 in conjunction with left ventricular outflow tract obstructive forms of congenital heart disease (CHD). This dissertation research aimed to delineate the biomedical significance of Mctp2 by investigating its expression and consequences of its genetic deletion in mouse models. Temporal and spatial expression of Mctp2 was investigated by RT-PCR and in-situ hybridization. A novel isoform, designated as isoform 2 in mice, results from alternative pre-mRNA splicing. Similar levels of Mctp2 isoforms 1 and 2 are present in embryonic tissues, whereas isoform 1 is preferentially expressed in adult tissues with high lipid metabolism. During mouse embryonic development, in-situ hybridization suggests expression of Mctp2 at the gut tube, liver bud and near the pharyngeal arches from E8.5 – E10.5. Given association of MCTP2 with CHD, the biological significance of Mctp2 was addressed using gene trap (GT) and conditional mouse models. Survival of Mctp2 GT mice was dependent on the genetic background strain, suggesting a role for strain-specific modifiers. Conditional knockout of Mctp2 in cardiac progenitor cells displayed no effect on survival. The role of Mctp2 in cardiac development remains to be delineated. The role of Mctp2 in cardiac function was addressed in both mouse models. Initial findings suggest Mctp2 allele dosage effects on the development of heart failure. GT mice lacking one, or both, copies of Mctp2 display cardiac systolic dysfunction, with upregulation of heart failure markers at 50 weeks of age in heterozygotes and increases in cardiac fibrosis in homozygotes. Systemic conditional deletion of Mctp2 did not show heart failure phenotypes using the strain protective from lethality. However, cardiac specific deletion of Mctp2 using the Nkx2.5-Cre driver, a line that is sensitized for cardiac dysfunction, led to decreased ejection fraction and fractional shortening in mice with conditional deletion of both copies of Mctp2 as well as Mctp2 dosage dependent penetrance of cardiac dilation. These studies of knockout mice suggest a role for Mctp2 in maintenance of cardiac function and possible genetic interaction with Nkx2.5. / 2022-02-02

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京都大学 / 新制・課程博士 / 博士(医学) / 甲第24314号 / 医博第4908号 / 新制||医||1062(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 小林 恭, 教授 松田 文彦, 教授 柳田 素子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Congenital heart disease (CHD) is the most common birth defect and often resultsin neurodevelopmental impairments and psychological problems which impede educational and occupational attainment and decrease overall quality of life into adulthood. While morbidity and mortality outcomes have improved over the last several decades, non-Hispanic black and Hispanic children continue to experience a disproportionate burden of CHD. An urban bioethics approach to disparities in cardiac neurodevelopmental outcomes necessitates an examination of the context, setting, and structures in which CHD care is delivered. This thesis proposes a model through which access to and quality of cardiac care impact disparities in neurodevelopmental outcomes. The thesis describes an initial evaluation of the proposed model conducted through retrospective record review. Though research funding and hospital resources have historically flowed toward optimizing surgical and other clinical care techniques, results indicate that factors such as poverty and other social determinants of health have a greater impact on many CHD outcomes. An urban bioethics framework asks us to additionally consider the ways in which cardiac care teams act as barriers to high quality care. Findings are discussed in terms of next steps and a proposed qualitative study to further evaluate results. / Urban Bioethics

Indiana University-Purdue University Indianapolis (IUPUI) / Congenital heart defects occur in approximately one percent of births every year, which makes it the most frequently occurring congenital defect in patients. The aim of this project was to use two mutant neural crest (NC) mouse models to study the mechanisms underlying congenital heart failure in utero. The first mouse model was a Pax3 systemic knockout, which was lethal by mouse gestational day 14, and had appreciably reduced numbers of migratory NC cells. The second mouse model was a Wnt1Cre-mediated NC genetic cell ablation model, which was surprisingly viable and survived to birth, despite an apparent lack of migratory NC cells. The resultant data indicated that both mouse models had similar heart structural defects including persistent truncus arteriosus, which was due to fewer or no migratory cardiac NC cells. However, in utero heart function was appreciably perturbed in Pax3 mutants when compared to that of the ablated mutant model. The loss of embryonic cardiac function in Pax3 mutants was directly attributed to a substantial decrease in the activity of the beta-adrenergic pathway. This was due to a lack of proper specification of trunk NC cells, leading to diminished levels of circulating catecholamine levels in the embryo. To definitively confirm this conclusion, poor cardiac function was successfully restored by pharmacological stimulation of the beta-adrenergic pathway via administration of isoproterenol and forskolin to pregnant dams, which led to embryonic survival of Pax3 mutants to birth. By comparison of these two mutant mouse models, perturbation in the beta-adrenergic pathway was identified as the underlying mechanism responsible for in utero heart failure and lethality in Pax3 mutant embryos. The results of this study are expected to be significant in developing future therapeutic targets for congenital heart failure in prenatal and newborn patients.

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Hypoplastic left heat syndrome (HLHS) is a complex cardiac malformation in neonates suffering from congenital heart disease and occurs in nearly 1 per 5000 births. HLHS is uniformly fatal within the first hours or days after birth as the severly malformed anatomies of the left ventricle, mitral, and aortic valves, and ascending aorta are not compatable with life. The regularly implemented treatment, the Norwood operation, is a complex open heart procedure that attempts to establish univenticular circulation by removing the atrial septum ( communicating the right and left ventricle), reconstructing the malformed aortic arch, and connecting the main pulmonary artery into the reconstructed arch to allow direct perfusion from the right ventricle into the systemic circulation. A relatively new treatment being utilized,the Hybrid Norwood procedure, involves a less invasive strategy to establish univentricular circulation that avoids a cardiopulmonary bypass (heart-lung machine), deliberate cardiac arrest, and circulatroy arrest of the patient during the procedure. The resulting systemic-pulmonary circulation is unconventional; blood is pumped simotaneously and in parallel to the systemic and pulmonary arteries after the procedure. Cardiac surgeons are deeply interested in understanding the global and local hemodynamics of this anotomical configuration. To this end, a multiscale model of the entire circulatory system was developed utilizing an electrical lumped parameter model for the peripheralor distal circulation coupled with a #D Computational Fluid Dynamics (CFD) model to understand the local hemodynamics. The lumped parameter (LP) model is mainly a closed loop circut comprised of RLC comartments that model cardiac function as well as the viscous drag, flow intertia, and compliance of the different atrial and venous beds in the body. A system of 32 first-order differential equations is formulated and solved for the LP model using a fourth-order adaptive Runge-Kutta solver. The output pressure and flow waveforms obtained from the LP model are imposed as boundary conditions on the CFD model. Coupling of the two models is done through an iterative process where the parameters in the LP model are adjusted to match the CFD solution. The CFD model domain is a representative HLHS anatomy of an infant after undergoing the Hybrid Norwood procedure and is comprised of the neo-aorta, pulmonary roots, aortic arch with branching arteries, and pulmonary arteries. The flow field is solved over several cardiac cycles using an implicit-unsteady RANS equation solver with the k-epsilon turbulence model.; Hypoplastic left heart syndrome (HLHS) is a complex cardiac malformation in neonates suffering from congenital heart disease and occurs in nearly 1 per 5000 births. HLHS is uniformly fatal within the first hours or days after birth as the severely malformed anatomies of the left ventricle, mitral and aortic valves, and ascending aorta are not compatible with life. The regularly implemented treatment, the Norwood operation, is a complex open heart procedure that attempts to establish univentricular circulation by removing the atrial septum (communicating the right and left ventricle), reconstructing the malformed aortic arch, and connecting the main pulmonary artery into the reconstructed arch to allow direct perfusion from the right ventricle into the systemic circulation. A relatively new treatment being utilized, the Hybrid Norwood procedure, involves a less invasive strategy to establish univentricular circulation that avoids a cardiopulmonary bypass (heart-lung machine), deliberate cardiac arrest, and circulatory arrest of the patient during the procedure. The resulting systemic-pulmonary circulation is unconventional; blood is pumped simultaneously and in parallel to the systemic and pulmonary arteries after the procedure. Cardiac surgeons are deeply interested in understanding the global and local hemodynamics of this anatomical configuration. To this end, a multiscale model of the entire circulatory system was developed utilizing an electrical lumped parameter model for the peripheral or distal circulation coupled with a 3D Computational Fluid Dynamics (CFD) model to understand the local hemodynamics. The lumped parameter (LP) model is mainly a closed loop circuit comprised of RLC compartments that model cardiac function as well as the viscous drag, flow inertia, and compliance of the different arterial and venous beds in the body.

No description available.

Maternal binge alcohol consumption has been linked to congenital birth defects in the fetus. Said defects include abnormalities in heart development, a category of disease referred to as Congenital Heart Disease. Given the prevalence of Congenital Heart Disease, with a study showing around 49.9% of women having at least participated in binge alcohol consumption at least once during the early stages of their pregnancy and Congenital Heart Disease being linked to various complications in adulthood, this is a topic relevant to the clinical setting. Alcohol consumption has been linked to decreases in DNA methylation, which generally increases transcriptional expression of nearby genes. This thesis will focus on how alcohol affects the genomic-wide epigenetics of the embryonic heart with the aim of identifying specific genes and sites within those genes that are affected by alcohol exposure in utero. We hypothesize that embryonic mouse hearts exposed to ethanol will show a differential methylation pattern characteristic of hypomethylation versus control hearts not exposed to ethanol. To test this hypothesis, we used oral gavage to administer ethanol to pregnant mice at embryonic age E9.5 (a time associated with heart chamber formation). Maternal mice were sacrificed at E11.5, embryonic hearts were removed, and DNA was extracted for further experimentation with whole genome bisulfite sequencing. Analysis of whole genome bisulfite sequencing data showed a slight trend towards hypomethylation but suggested no significant changes in the overall methylation pattern in embryonic mouse hearts at the genomic level, but we have independently identified several genes whose expression is depressed in the embryonic mouse following a single maternal binge ethanol dose at E9.5, and thus we are investigating potential alcohol-induced DNA methylation alterations in specific target genes of interest. Future investigations into gene and site-specific DNA methylation profiles as well as other epigenetic modifications should prove useful in our quest to learn how maternal alcohol consumption causes cardiac malformations leading to congenital heart disease.