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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Detection of Modality-Specific Properties in Unimodal and Bimodal Events during Prenatal Development

Vaillant, Jimena 01 September 2010 (has links)
Predictions of the Intersensory Redundancy Hypothesis (IRH) state that early in development information presented to a single sense modality (unimodal) selectively recruits attention to and enhances perceptual learning of modality-specific properties of stimulation at the expense of amodal properties, while information presented redundantly across two or more modalities (bimodal) results in enhanced perceptual learning of amodal properties. The present study explored these predictions during prenatal development by assessing bobwhite quail embryos’ detection of pitch, a modality-specific property, under conditions of unimodal and redundant bimodal stimulation. Chicks’ postnatal auditory preferences between the familiarized call and the same call with altered pitch were assessed following hatching. Unimodally-exposed chicks significantly preferred the familiarized call over the pitch-modified call, whereas bimodally-exposed chicks did not prefer the familiar call over the pitch-modified call. Results confirm IRH predictions, demonstrating unimodal exposure facilitates learning of modality-specific properties, whereas redundant bimodal stimulation interferes with learning of modality-specific properties.
2

Morphological changes in chick embryo neural tissue associated with hydrocortisone use during prenatal development

Smit, Eureka 10 May 2007 (has links)
Glucocorticoids known to be such powerful agents that cell growth, differentiation and cell death are influenced in the brain of mammals throughout life. Despite this, relatively little toxicological information regarding prenatal exposure is available. The aim of this study was to determine the effect of prenatal hydrocortisone exposure on cell viability and cell morphology in chick embryonic neurons. Four different histological staining techniques namely, Hematoxylin and Eosin (H&E), Cresyl Fast Violet, Silver impregnation and a combination of Gold Chloride and Toluidine Blue were used to evaluate chick embryo neural tissue exposed to 0.137ƒÝM or 0.685ƒÝM hydrocortisone on day 3.75 (Carnegie stage 16) and day 5.5 (Carnegie stage 18) of development. Histological processing was optimized and neural tissue evaluated for any changes in neuron morphology and cell number. Specific ultrastructural changes to membraneous structures were evaluated by transmission electron microscopy (TEM). Fixation procedures that resulted in little to no disruption of these structures were optimized and used in studies evaluating the effect of hydrocortisone on neuron morphology. Primary chick embryonic neuronal cultures were prepared and increasing concentrations of hydrocortisone (26.3nM, 0.16ƒÝM, 0.63ƒÝM, 3.8ƒÝM, and 22.8ƒÝM) added. Fluorescence microscopy was applied to the in vitro hydrocortisone exposed primary neuronal cultures. A combination of fluorescein diacetate (FDA) and propidium iodide (PI) was used to evaluate the effect of hydrocortisone on cell viability, whereas dichlorodihydrofluorescein diacetate (DCH2FDA) was used to visualize reactive oxygen species (ROS) generation in neurons. Histological evaluation of the neural tissue of chick embryos exposed to 0.137ƒÝM and 0.685ƒÝM hydrocortisone showed reduced neuron density and morphological changes associated with cell death. Glutaraldehyde with added magnesium chloride (MgCl2) as stabilizing chemical and potassium permangenate were two fixatives that caused minimal disruption to neural tissue. These two fixating methods were applied to control neural tissue as well as tissues exposed to 0.137ƒÝM and 0.685ƒÝM hydrocortisone. When evaluated by TEM, the control tissue appeared to be intact with no displacement. Exposure of neurons to 0.137ƒÝM hydrocortisone appeared to have severe effects on the morphology of the mitochondria, endoplasmic reticulum (ER), nuclear and plasma membranes. More extensive damage was noted with 0.685ƒÝM hydrocortisone, leaving almost no cellular structure. Both concentrations of hydrocortisone indicated cell death associated with apoptosis and necrosis. In vitro studies using primary cultures of chick neurons indicated that hydrocortisone is non-toxic at low concentrations (26.3nM ¡V 3.8ƒÝM) with the percentage viability ranging between 73% and 88%. A more toxic effect was seen at high concentrations (22.8ƒÝM). Cell death at the higher concentrations (22.8ƒÝM and 3.8ƒÝM) of hydrocortisone occurred due to ROS generation, as indicated by DCH2FDA fluorescence In conclusion, hydrocortisone indicated neurotoxicity at high concentrations of exposure. Although cell death could be detected, the exact mechanism (apoptosis or necrosis) still needs to be investigated. Since the developing brain is so susceptible to chemical insults care should be taken when administering this drug to pregnant mothers or young children. / Dissertation (MSc (Cell Biology)))--University of Pretoria, 2007. / Anatomy / unrestricted
3

Prenatal Pathways to Early Puberty: Testing the Thrifty Phenotype and Fetal Overnutrition Hypotheses

Olivia C Robertson (11647522) 08 November 2021 (has links)
<p>This thesis outlined a novel operationalization and extension of the thrifty phenotype and fetal overnutrition hypotheses, two evolutionary developmental hypotheses stemming from the developmental origins of health and disease perspective, for developmental pathways from prenatal risk through child growth to early puberty. Support has accumulated for both, but previous studies have not clearly determined which hypothesis better predicts early puberty. Using the Fragile Families and Child Wellbeing Study (<i>n</i>=4898), the thrifty phenotype and fetal overnutrition pathways were tested against each other, separately by sex, and race/ethnicity for adrenal, and gonadal pubertal markers. Results indicated that in general, both hypotheses were supported. Contrary to hypotheses, the thrifty phenotype pathway did not predict perceived pubertal timing better in boys and the fetal overnutrition pathway did not predict perceived pubertal timing best in girls. Instead, both pathways predicted puberty equally well between girls and boys and the fetal overnutrition pathway stemming from maternal gestational weight gain was stronger than the pre-pregnancy BMI pathway. Individual paths of the hypothesized pathways were generally supported when analyzed by race/ethnicity group separately, but support for the entire pathways were sparse. Implications of this work are that pubertal timing may be similarly programmed by restrictive and overnutrition prenatal risks, both should be prioritized, and that interventions for maternal gestational weight should be prioritized over interventions for pre-pregnancy BMI for reducing rates of early puberty. </p>
4

Cleft Lip and/or Palate in Infants Prenatally Exposed to Opioids

Proctor-Williams, Kerry, Louw, Brenda 01 January 2021 (has links)
Objective: To determine the prevalence and odds ratios for cleft lip and/or palate (CL/P) among infants prenatally exposed to opioids with or without neonatal opioid withdrawal syndrome (NOWS). Design: This study represents an exploratory, retrospective cohort study design of newborn medical health records from 2011 to 2016. Setting: Records were drawn from a regional health system located in South Central Appalachia. Population and Study Sample: The original population yielded 3 cohorts of infants: (1) infants with opioid exposure (OE) but not requiring pharmacological intervention (OE; N = 168); (2) infants with NOWS requiring pharmacological intervention (N = 294); and (3) infants with no opioid exposure (NOE; N = 16 090), the primary comparison group. Main Outcome: Infants in the NOWS and OE groups showed significantly increased prevalence and odds ratios for CL/P when compared to those in the NOE group. Results: Prevalence rates per 1000 live births for infants with OE (35.71) and infants with NOWS (6.80) were significantly higher than those for infants with NOE (1.37). Comparison of infants with OE to the NOE group revealed significantly increased odds for CL/P, isolated cleft palate (CP), cleft lip (CL), and cleft lip and palate (CLP) (27.05, 41.81, 19.26, 19.37, respectively; all Ps <.008). The odds ratios for infants with NOWS compared to the NOE group were significantly higher for CL/P and CP (5.00 and 10.98, respectively; Ps <.03) but not for CL and CLP. Conclusion: The results provide additional evidence that prenatal OE should be considered among the critical environmental risk factors that can contribute to CL/P.
5

Rodičovské konflikty a speciace u myši domácí / Parental conflicts and speciation in the house mouse

Kropáčková, Lucie January 2012 (has links)
Hybridization between closely related species of mammals is often accompanied by abnormal growth of placentas and fetuses. From the perspective of evolutionary biology, our knowledge about the contribution of such interspecies incompatibilities in speciation is still insufficient. In my thesis, I was finding out if abnormal placental and fetal growth contributes to reproductive isolation of two subspecies of house mouse, Mus musculus musculus and M. m. domesticus, which are at an early phase of speciation and in nature they still hybridize. Using two inbred strains derived from M. m. musculus (PWD/Ph, STUS) and two inbred strains derived from M. m. domesticus (C57BL6/J, SCHEST) we performed four different intrasubspecies and four different intersubspecies crosses. We found out that the size of the placenta in hybrids is more influenced by father, while the size of the fetus is more influenced by mother. After elimination influence of weight of mother and father we have not recorded a significant difference in the size of placentas and fetuses in intrasubspecies and intersubspecies crosses. Our results show that hybridization between subspecies of house mouse does not produce abnormalities in prenatal development, as was observed in hybrids between distant species of mice. It is thus possible that...
6

Cleft Lip and/or Palate in Infants Prenatally Exposed to Opioids

Proctor-Williams, Kerry, Louw, Brenda 07 May 2021 (has links)
Objective: To determine the prevalence and odds ratios for cleft lip and/or palate (CL/P) among infants prenatally exposed to opioids with or without neonatal opioid withdrawal syndrome (NOWS). Design: This study represents an exploratory, retrospective cohort study design of newborn medical health records from 2011 to 2016. Setting: Records were drawn from a regional health system located in South Central Appalachia. Population and study sample: The original population yielded 3 cohorts of infants: (1) infants with opioid exposure (OE) but not requiring pharmacological intervention (OE; N = 168); (2) infants with NOWS requiring pharmacological intervention (N = 294); and (3) infants with no opioid exposure (NOE; N = 16 090), the primary comparison group. Main outcome: Infants in the NOWS and OE groups showed significantly increased prevalence and odds ratios for CL/P when compared to those in the NOE group. Results: Prevalence rates per 1000 live births for infants with OE (35.71) and infants with NOWS (6.80) were significantly higher than those for infants with NOE (1.37). Comparison of infants with OE to the NOE group revealed significantly increased odds for CL/P, isolated cleft palate (CP), cleft lip (CL), and cleft lip and palate (CLP) (27.05, 41.81, 19.26, 19.37, respectively; all Ps < .008). The odds ratios for infants with NOWS compared to the NOE group were significantly higher for CL/P and CP (5.00 and 10.98, respectively; Ps < .03) but not for CL and CLP. Conclusion: The results provide additional evidence that prenatal OE should be considered among the critical environmental risk factors that can contribute to CL/P.
7

Influence of Microbial Products on the Developmental Programming of the Enteric Nervous System

Popov, Jelena January 2018 (has links)
Bacterial colonization of the gastrointestinal (GI) tract takes place during the perinatal period, thus coinciding with a critical window of enteric nervous system (ENS) development. Previous work has found that the myenteric plexus of germ free (GF) mice exhibits structural and functional aberrancies in the early postnatal period as compared to specific pathogen free (SPF) and altered Schaedler flora (ASF) mice. These early life disruptions in ENS development in GF mice compared to SPF mice, and more specifically ASF mice, support the notion that a simple intestinal flora is sufficient for directing perinatal ENS development. It has previously been believed that the intrauterine environment during fetal development is sterile. Recent evidence showing successful isolation of microbial communities from embryonic cord blood and newborn meconium that are not of maternal origin suggests that the intrauterine environment is not sterile and is unique to the fetus. Coinciding with this timeline of fetal microbial colonization is the development of the ENS through a population of precursors known as enteric neural crest derived cells (ENCDCs). The prenatal period is characterized by rapid expansion and differentiation of ENCDCs into the many enteric neuron subtypes that comprise the ENS. Terminal differentiation of ENCDCs continues into the early postnatal period. In the current study, we tested the hypothesis that ENCDCs interact directly with microbial products during ENS development. Further, these ENCDC-bacterial product interactions influence the proliferation, apoptosis, and chemical coding of enteric neuron precursors. These objectives were carried out in an in vitro model of ENCDCs isolated from the prenatal period that was established for the first time in our lab using immunoselection. Further, this model was characterized at key timepoints for proliferation, apoptosis, and differentiation. Our results are suggestive of direct ENCDC interactions with lipopolysaccharide (LPS), a TLR4 ligand, and flagellin, a TLR5 ligand, in stimulating ENCDC proliferation and differentiation into early born neurons of nitrergic and serotonergic subtypes. Peptidoglycan derivatives, muramyl dipeptide (MDP) and ƴ-D-Glu-mDAP (iE-DAP), ligands for NOD2 and NOD1 respectively, appear to mainly stimulate differentiation into nitrergic neurons, and possibly serotonergic neurons. The lack of apoptosis in all conditions is consistent with the notion that apoptosis is not an important characteristic of ENCDC maturation and ENS development. Finally, the lack of significance for differentiation into dopaminergic neurons could be further evidence of their late born nature, which has previously been reported to be stimulated by serotonin after the emergence of serotonergic neurons. / Thesis / Master of Science (MSc)
8

Vliv psychosomatické situace matek v těhotenství na prenatální vývoj dítěte / Influence of the psychosomatic situation of mothers in pregnancy on the prenatal development of the child and condition of newborn after delivery

ŠIMEČKOVÁ, Alžběta January 2018 (has links)
Current status: Mental well-being in pregnancy is one of the most beautiful moments in a woman's life. It's such a miracle experience. There is a period of complete change with pregnancy. Both women and their partners are changing their living standards, changing their lifestyle, and changing their life position. A pregnant woman feels that nothing will be like before. A pregnant woman is very sensitive and also vulnerable. Purpose:The aim of the diploma thesis is to evaluate the psychosomatic situation of the pregnant woman and her influence on the prenatal and postnatal development of the child. Another goal is to determine the degree of mental (non) well-being during pregnancy and after delivery. Methods: Qualitative secondary analysis of data and documents and subsequent synthesis of the information obtained was used to achieve the objectives set. I used the data from the National Medical Library in Prague, the library of 2. LF UK and FN Motol in Prague, the library of National center of nursing and non-medical health providers in Brno and the Academic Library of the University of South Bohemia in České Budějovice. Also searched were the international internet database ScienceDirect, Ebscohost, PubMed. In the Scopus database, keyword search was unsuccessful. Results:The benefit of the diploma thesis is the degree of psychological well-being of pregnant women using the Freybergh scale on the basis of acquired data. Research method and research file: The diploma thesis uses a standardized evaluation method, using the Freybergh scale consisting of seventy closed questions. I will get the approval of the respondents and also Mr Freyberg, using a standardized scale. The annex is the approval of Professor Freyberghov, using the assessment scale in my diploma thesis. Respondents were ad-dressed from February 2017 until February 2018. A total of 30 pregnant women were approached by a written form, personal handover or social networking, of which fifteen were willing to engage in research. The research group was to consist of fifteen pregnant women, which is fulfilled. I responded to each respondent in third, sixth, ninth month pregnancies, and postpartum. When the respondents filled the same rating ranges from seventy questions both in the given months of pregnancy and postpartum, the respondents' task was to express the frequency of occurrence of feelings on a four-point scale from "never, at all", "rarely, exceptionally", "occasionally", "often" to "always, always, always". The nine respondents were first pregnant and six respondents had at least one pregnancy experience. The evaluation was performed using a qualitative method in the form of axial and selective coding of anchored claims using the Atlas.ti computer program. Conclusion: The paper deals with the degree extent of pregnancy psychosomatics of pregnant women using the Freybergh self-rating scale. The thesis is divided into two parts, namely the theoretical part and the practical part. The theoretical work focuses on the development of the fetus throughout pregnancy. It also focuses on prenatal psychology, prenatal history, and the most important part is prenatal communication. In the practical part is selected quantitative research focused on the psychological well-being of pregnant women using the Freybergh scale in selected months of pregnancy.

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