Dissertations / Theses on the topic 'Fetal heart development'

Glucocorticoids are steroid hormones that affect a variety of physiological and pathological processes both throughout development and in adult life. During mammalian fetal growth, the late gestation rise in fetal glucocorticoid levels is essential for the maturation of tissues and organs in preparation for birth. In humans, glucocorticoids are routinely administered to women threatened by a preterm labour to accelerate fetal lung maturation and prevent neonatal respiratory distress and mice lacking glucocorticoid receptor (GR-/- mice) die neonatally as they are unable to inflate their lungs due to severe pulmonary immaturity. Apart from their importance for proper lung maturation, the physiological role of glucocorticoids in the development of other organs and tissues is not well known. However, prenatal exposure to excess glucocorticoids was shown to elicit detrimental “programming” effects, raising the susceptibility to adult diseases such as hypertension, obesity and metabolic disturbances in both humans and animal models. I therefore used global and conditional GR knock out mouse models to investigate the role and importance of adequate glucocorticoid signalling in fetal heart development and maturation. I further confirmed the direct effects of glucocorticoids on the cardiomyocyte structure and function in an in vitro setting. GR-/- fetuses are under-represented in late gestation (>50% of the number of GR+/+ littermates) but are present in the expected mendelian ratio at E14.5. At E17.5, GR-/- fetuses show edema (increased fluid accumulation and body sodium content). Excess extracellular fluid accumulation could be a result of a congenital heart failure. During development, corticosterone levels sharply increase within the fetal hearts at E15.5-E16.5, coincident with nuclear translocation of GR. Consistent with activation of GR only after this time, the phenotypic consequences of GR deficiency can be seen after E16.5 and not before. At E17.5, hearts of GR-/- fetuses are smaller than in GR+/+ but display no structural abnormalities. Cardiac function however is severely impaired, with left ventricular systolic and diastolic performance inferior in GR-/- fetuses compared to their wild-type littermates. Microscopically, at E17.5, the structure of the cardiac muscle and individual cardiomyocytes are affected by the lack of GR. The normal outer muscle layer, with characteristic rod-shaped, aligned cardiomyocytes is not discernable in the GR-/- heart. Within the cardiomyocytes, myofibrils are short, undefined and randomly scattered within the cell. Lack of the maturational progression in the GR-/- hearts at E17.5 is evident in the pattern of gene expression. GR-/- fetuses do not display the normal gestational changes between E14.5 and E17.5 that are seen in control mice, including in genes involved in the maturation of cardiac structure (eg myosin heavy chain-α, MyHC-α), function (atrial natriuretic peptide, ANP), energy metabolism (eg hexokinase-1, PPARγ coactivator-1α, PGC-1α) and calcium handling (ryanodine receptor, RyR; sarcoplasmic reticulum Ca2+-ATPase, SERCA2a). However, there are no genotype or gestational alterations in mRNA encoding the mineralocorticoid receptor, which is also a receptor for glucocorticoids in the heart. The normal gestational changes in the levels of modified histone H3 associated with the promoters of some of the genes (MyHC-α, ANP, PGC-1α) are not seen in hearts of GR-/- fetuses. This cardiac phenotype was not secondary to adrenal catecholamine insufficiency reported in other GR-/- models, as peripheral tissue levels of adrenaline were not different between genotypes. In order to test the hypothesis that the effects of glucocorticoids on the heart are mediated via GR in cardiomyocytes and to further elucidate the direct effects of GR deficiency specifically within the heart, mice with conditional deletion of GR selectively in cardiac and vascular smooth muscle cells were generated ("SMGRKO" mice). These show ~65% reduction in cardiac GR mRNA and protein levels. Circulating levels of corticosterone do not differ between genotypes at E17.5. SMGRKO fetuses at E17.5 display a phenotype strikingly similar to that of global GR-/-, namely edema, impaired cardiac function, impaired cellular architecture within the ventricle and alterations in the gene expression, implying that the GR-deficient phenotype is largely due to the direct actions of GR within the heart and not secondary to effects on other systems (eg kidney or liver). In order to investigate the pathways by which GR stimulates cardiomyocyte maturation, an in vitro model of murine primary fetal (E15.5-E16.5) cardiomyocytes was developed. Cultures contain >98% of troponin Tpositive cells which beat spontaneously. Treatment of cardiomyocytes with either synthetic (dexamethasone) or physiological (corticosterone) glucocorticoid induces time- and dose-dependent changes in gene expression, consistent with glucocorticoid-dependent changes seen in vivo in the late gestation heart. The effects of glucocorticoids on gene expression were abolished by either siRNA mediated knock-down of GR or RU486 antagonism of GR, but were unaffected by a mineralocorticoid receptor (MR) antagonist. Moreover, cycloheximide pretreatment (to block protein synthesis) suggested PGC-1α as a direct genomic target of GR. RNAseq transcriptome analysis performed on cardiomyocytes treated with dexamethasone and cycloheximide for 2h identified >600 genes as possible rapid and direct glucocorticoid response targets. Among them are genes involved in energy metabolism, calcium handling and sarcomere assembly. Glucocorticoid treatment of fetal cardiomyocytes also induces striking structural changes – formation of stress troponin T-associated actin fibers and sarcomere assembly. Spontaneous contractile activity is improved by glucocorticoid treatment, with a decrease in both contraction and relaxation time (without a change in frequency) and an improvement in the relaxation kinetics. In summary, glucocorticoid signalling in cardiomyocytes is required for the functional, structural and transcriptional maturation of the fetal heart in late gestation in vivo. Glucocorticoid treatment of primary murine fetal cardiomyocytes replicated the contractile, transcriptional and structural changes seen in vivo and was dependent on GR. Thus, GR is essential in cardiomyocytes for the structural and biochemical changes that underlie the maturation of heart function around the time of birth and an inadequate glucocorticoid environment could potentially lead to detrimental and permanent changes in postnatal cardiac function. Since prenatal glucocorticoids are routinely used clinically, it is important to consider any possible effects they might have on the heart development and its function later in life.

Nowadays ultrasonography represents the gold standard method for the evaluation of canine fetal development and health. In dogs, the gestational age is estimated by the ultrasonographic measurements of extra-fetal and fetal structures. The fetal development has been deeply investigated in small and medium dogs, whereas only few information are available for large and giant size bitches, even though they are very popular canine breeds. The measurements of the inner chorionic cavity (ICC) in early pregnancy, and the biparietal diameter (BP) in late pregnancy are commonly used in clinical practice. Both ICC and BP are highly reliable when size-related specific formulae are applied, thus, specific equations for large and giant dogs would allow the most accurate prediction of parturition term. Only few parameters are available to objectively assess the fetal health during canine pregnancy. Among them, the fetal heart rate (FHR) is generally used, but the relationship between FHR and maternal heart rate (MHR) has been poorly investigated. The availability of reference values of the ratio FHR/MHR, could better contribute to the evaluation of the fetal health at different gestational ages, than the single FHR values. The aims of this study were 1) to derive the growth curves of extra-fetal and fetal structures (ICC and BP) in large and giant size bitches and to evaluate their accuracy (Paper 1); 2) to evaluate the trend of FHR and of the ratio FHR/MHR in bitches of different pre-gestational bodyweight (Paper 2). Present results showed a significant relationship between days before parturition and ICC or BP in large and giant size bitches. The overall accuracy ±2 days of both parameters was significantly higher than the accuracy ±1 day. Only in giant bitches, the BP accuracy of the prediction was significantly lower in small than normal litter size. As previously observed in other sizes dogs, the gender did not affect the accuracy of the prediction. The second study demonstrated that both FHR and FHR/MHR significantly fitted a multiple quadratic regression for all independent variables. They both resulted higher in low and high bodyweight, and reached the maximum values at about 20 days before parturition. Maternal pre-gestational bodyweight and the gestational age influenced both FHR and FHR/MHR. The highest significance of FHR/MHR, compared to FHR, encourages the application of this ratio, to evaluate fetal health. The derived equation for FHR/MHR ratio, that describes the trend in healthy fetuses, could be helpful in clinical practice to derive expected values in uncomplicated pregnancies.

Introdução: Diversos estudos indicaram consequências de alterações na nutrição materna durante a gestação sobre a saúde da prole adulta, tais como: hipertensão, doenças cardiovasculares, resistência à insulina, diabete melito e doença renal. No entanto, a literatura é pobre em avaliações decorrentes de modificações nutricionais maternas sobre a prole logo após o nascimento. Métodos: Ratas Wistar durante o período gestacional foram alimentadas com dieta hipossódica (HO - 0,15% de NaCl), normossódica (NR - 1,3% de NaCl) ou hipersódica (HR - 8% de Na Cl). Após o nascimento, nas primeiras vinte e quatro horas foram coletados rins e coração dos neonatos machos e fêmeas (n=6- 8/grupo) para verificar as possíveis alterações na estrutura cardíaca e renal pelo método de estereologia. Também foi avaliada a expressão proteica e gênica dos componentes do sistema renina angiotensina (SRA) no coração e rins através do método ELISA indireto e RT-qPCR. Resultados: O peso ao nascimento foi menor em machos e fêmeas da prole de mães alimentadas com dieta hipossódica durante a gestação quando comparado NR e HR. Não houve diferença no volume renal, volume de seus compartimentos (córtex, medula e pelve) e número de glomérulos entre os grupos experimentais (HO, NR e HR). No entanto, o número de glomérulos foi maior em fêmeas comparado aos machos nos três grupos experimentais. O diâmetro transverso do núcleo dos cardiomiócitos no ventrículo esquerdo e no ventrículo direito de machos da prole HR foi maior do que na prole NR. A expressão proteica do receptor AT1 no rim de machos da prole foi menor no grupo HO do que no grupo NR e HR. A expressão proteica do receptor AT2 também foi menor em machos do grupo HO do que no grupo NR. Não houve diferença entre os grupos na expressão proteica dos receptores AT1 e AT2 no rim das fêmeas. Conclusão: O presente estudo detectou alterações na estrutura cardíaca de neonatos machos, mas não em neonatos fêmeas decorrentes de sobrecarga de sal durante a gravidez. As alterações observadas na expressão dos receptores AT1 e AT2 no rim de neonatos machos podem ser responsáveis por alterações na função renal
Introduction: Several studies have shown several consequences on adult offspring due to alterations in maternal nutrition during pregnancy, such as: hypertension, heart diseases, insulin resistance, diabetes mellitus and kidney diseases. Nevertheless, few studies evaluated maternal nutritional alterations in neonates. Methods: Female Wistar rats where fed from day one of pregnancy until delivery with low- (LS - 0.15% NaCl), normal- (NS - 1.3% NaCl) or high- (HS - 8%NaCl) salt diet. During the first twenty-four hours after birth, newborn\'s (n=6- 8/group) kidneys and heart were collected to evaluate possible changes of their structure by stereology. The protein and the gene expression of the renin angiotensin system components were evaluated by indirect ELISA and by RTqPCR, respectively. Results: Birth weight was lower in male and female offspring of dams fed LS during pregnancy. No differences between groups (LS, NS and HS) were observed in total renal volume and its compartments (cortex, medulla and pelvis) and number of glomeruli. The number of glomeruli was higher in female when compared to male newborns in the three experimental groups. The transverse diameter of the nuclei of the cardiomyocytes was higher in HS in both left and right ventricle vs. NS. The AT1 receptor protein expression was lower in kidneys of LS than in NS and HS male newborns. AT2 receptor protein expression was also lower in male LS than in NS. No differences in AT1 and AT2 receptors protein expression in female newborn\'s kidneys were found. Conclusion: The present study shows changes in cardiac structure male but not of female neonates induced salt overload during pregnancy. The alterations observed in AT1 and AT2 expression in kidneys of neonates may be responsible for alteration in renal function

碩士
中原大學
生物醫學工程研究所
103
Fetal heart rate monitoring is one of the main approaches for obstetricians to determine the fetal well-being during pregnancy. Since different fetal position results in different position for heart sound monitoring. This study develops a prototype of fetal heart sound monitor system using microphone array. The system uses the statistical results of the energy of signal from microphone array to detect the main fetal position, so that we can acquire fetal signal with the best signal quality and obtain more accurate fetal heart rate. Furthermore, with the android application, developed in this study, the fetal heart sound signal and fetal heart rate that are transmitted using Bluetooth module can be displayed in real-time. In addition, the APP can storage records and establishes a database to provide user the capability to view past records. There are three stages in real signal acquisition. In total, 18 subjects were recruited with different weeks of pregnancy in the test. The results not only demonstrate that the proposed system is capable of recording high quality fetal heart sound but also prove the main position of the fetal determines the quality of the signal. That is, with only 5 cm off center, the impact on the signal quality is significant. In the area of MATLAB algorithm validation, using the acquired real signal, the accuracy of fetal main position determination and the fetal heart rate computation are compared with the expert. The result shows that our algorithm can determine the fetal main position correctly and the averaged accuracy of extracting fetal heart rate can reach 98.6%. In the system integration, this study realizes a real time system on the DSP. In a 5 minutes test session, the system can determine the fetal main position correctly. While illustrating the results of fetal heart rate using the Bland-Altman difference plot, the fetal heart rate differences between real-time system and the MATLAB are within 3bpm. In conclusion, this study develops a prototype for fetal heart sound monitor system using microphone array. Using the proposed algorithm the system can successfully extract high quality fetal signal and obtain more reliable fetal heart rate.

碩士
慈濟大學
神經科學研究所
91
Fetal heart rate variability (FHRV) is the most important parameter of fetal well-being. To date, visual inspection is a more popular method to analyze FHRV, but it is relatively subjective and qualitative. To develop a non-invasive and quantitative method to detect the fetal heart rate, we recorded the fetal heart sounds of the normal pregnancy women who visiting the OPD of Yu Li Veterans Hospital for prenatal care. Fetal heart sounds were recorded for 2.5 minutes with supine position in a quite room. Fetal heart sounds were detected from a mini-microphone in conjunction with abdominal ultrasound, ultrasound fetoscope, and fetal monitor. The off-line data was analyzed by self-designed program software with fast Fourier transform and spectral analysis. Frequency domain analysis of beat-to-beat intervals including very low frequency power (VLF, 0.003-0.04 Hz), low frequency power (LF, 0.04-0.15 Hz), high frequency power (HF, 0.15-0.4 Hz) and the ratio of LF to HF (LF/HF) were performed. Ninety-four recording trials from 76 pregnancy women were recorded in this study and 48 were selected to be quantitatively analyzed. Three groups were defined: 1st trimester (gestational age of 9-14 week, N = 5); 2nd trimester (gestational age of 15-28 weeks, N = 18) and 3rd trimester (gestational age of 29-41 weeks, N = 25). The results showed that fetal heart rate was decreased by gestational age significantly. VLF, LF, HF and TP were increased significantly and LF/HF decreased in the 3rd trimester. Heart rate of male fetus was significantly higher than female only in the 3rd trimester. We concluded that Power spectral analysis of FHRV is a non-invasive, convenient method and spectral analysis of fetal heart rate variability by Doppler ultrasound is feasible. The heart rate of male fetus was higher than female significantly in the third trimester. It seems that the parasympathetic activity of fetal autonomic state was increased significantly in the 3rd trimester. And the decrease of LF/HF may be the indicator of maturity of autonomic nervous system in fetal development.

碩士
國立交通大學
生物資訊研究所
95
Heart development is a complex process involving many genes which control cell behavior in the embryo and determine its pattern, its form, and much of its behavior. Microarray experiments can generate an enormous amount of data at one time, so we use this technology to obtain gene expression profiles in heart embryonic development. But it is usually very difficult to obtain human heart fetus sample because of the issues of ethical, legal, and social consideration. In order to help us get more understanding of human heart development, we can use the mouse model system that is most often used. Therefore, we must establish a mapping system to make a cross bridge between these two species on developmental stages. To date, the vast majority of researches have focused their study on one species. Specially, we utilize orthologous genes and incorporate the dynamic time warping algorithm in order to map the time points that human and mouse gene expression profiles having highly correlated pattern. Firstly, we apply the algorithm to select the best time-warped orthologous genes having similar pattern. Then, these genes are clustered into groups. Each group has its unique mapping pattern and different biological meaning. The following task is to find relationship and pattern in distinct groups of genes, and to get close understanding into molecular process and gene function, mechanisms of embryogenesis of the heart, and comparative genomics. Ultimately, our aim is to achieve new insights into the heart developmental biology.

Une diète faible en sodium donnée à des rates lors de la dernière semaine de gestation induit une diminution de l’expansion volumique, du diamètre des artères utérines et du poids des placentas comparativement à des rates témoins. Ces perturbations suggèrent une diminution de la perfusion placentaire affectant l’apport foetal en nutriments. Les ratons naissent avec une restriction de croissance intra-utérine (RCIU). Chez le foetus, le substrat énergétique cardiaque principal est le glucose via la glycolyse. À la naissance, la source principale d’énergie est l’utilisation des acides gras par la β-oxydation. Nous émettons l’hypothèse que dans ce modèle de RCIU, le coeur foetal répond à la diminution d’apport nutritionnel due à une atteinte maternelle en adaptant son métabolisme énergétique cardiaque à la baisse. Les rates gestantes (témoins et recevant la diète faible en sodium) sont sacrifiées au jour 22 de gestation (sur 23). Les coeurs foetaux sont prélevés afin de caractériser les protéines dites « limitantes » in vitro des voies de la glycolyse et de la β-oxydation. Les expressions protéiques de GLUT1, GLUT4, HK1, HK2, CPT2, CPT1β, cytochrome c, PFK1, PKM1/2, mesurées par immunobuvardage de type Western, sont similaires entre les coeurs des foetus RCIU et témoins, mâles et femelles. L’expression protéique de CPT1α est diminuée dans les coeurs des femelles RCIU seulement. Il n’existe aucune différence significative entre les différents groupes quant à l’activité enzymatique de PKM1/2. Nos résultats dressent un profil métabolique général suggérant que le sexe du foetus peut avoir un effet sur la réponse cardiaque foetale à une atteinte du volume sanguin maternel causée par la diète restreinte en sodium. Ce profil métabolique semble démontrer une atteinte du catabolisme des lipides. Afin de bien caractériser cette réponse du mécanisme énergétique, l’activité enzymatique des autres enzymes principales de la glycolyse (HK1, HK2, PFK1), le flux intra-mitochondrial d’acyl CoA à travers les CPTs ainsi que la quantité totale d’acétyl CoA devront être quantifiés.
A low sodium diet was given to pregnant rats during the last week of gestation. This diet diminished the maternal expansion of blood volume, the uterine arteries diameter, and placental weight, when compared to their controls. Together, these results suggest a lower placenta perfusion and a decreased output of nutrients to the fetus. The offspring of these pregnant rats were born with an intra-uterine growth retardation (IUGR). The fetal heart utilizes glucose through glycolysis as the major cardiac energy substrate. At birth, the principal source of energy switches to the oxidation of fatty acids, through β-oxydation. We hypothesized that within our IUGR model, the fetal heart could respond to a diminished nutritional intake due to the maternal input when a decreased cardiac energy metabolism was present. The pregnant rats of both groups (controls and on the low sodium diet) were sacrificed on day 22 of a 23 day gestation. The fetal hearts were then analyzed looking for signs of the limiting proteins glycolysis and β-oxidation. The GLUT1, GLUT4, HK1, HK2, CPT2, CPT1β, cytochrome c, PFK1, PKM1/2 proteins obtained through a Western immunoblot method were similar between the hearts of the IUGR and their control fetuses, whether they were male or female. The protein expression of CPT1α was lower only in female IUGR fetal hearts. There was no significant difference between the groups with respect to the enzymatic activity of PKM1/2. Our results suggest that the metabolic profile changes with regards to the fetus gender and could affect the fetal cardiac metabolism, due to a lower maternal blood flow caused by a sodium controlled diet, by diminishing its lipid metabolism and sparing glucose metabolism. To characterize the energy metabolism, the enzymatic activity of the other principal limiting enzymes glycolysis (HK1, HK2, PFK1), the intra-mitochondrial flux of acyl CoA through the CPTs and the total quantity of acetyl CoA must also be analyzed.