Browsing by Author "Raghunathan, Raksha"
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Item Assessing Mouse Brain Elasticity Using Air-Pulse Based Optical Coherence Elastography(2017-10-12) Goh, Megan; Liu, Chih-Hao; Singh, Manmohan; Raghunathan, RakshaCurrent diagnostic methods are able to detect severe brain trauma but are unable to detect the microscopic brain injuries that regularly occur during a concussion. Our research aims to explore a potential alternative method to detect a wider range of severity in concussions through comparing the changes in the biomechanical properties of pre- and post-concussed brain tissue using optical coherence elastography (OCE). This study is a proof of concept to see if OCE can distinguish different regions within the brain based on biomechanical properties. In this study, we hope to distinguish the hippocampus, a complex structure located in the medial temporal part of the brain beneath the cerebral cortex, from the rest of the brain. Our results show that the hippocampus is softer than the cortex of the brain, which corresponds to currently available literature. In this study, we were able to show that OCE could detect differences in the biomechanical properties of different regions of the brain.Item Assessing Teratogen-Induced Changes in Murine Fetal Brain Vasculature Using In Utero Optical Coherence Tomography(2020-05) Raghunathan, Raksha; Larin, Kirill V.; Miranda, Rajesh C.; Gifford, Howard C.; Zhang, Yingchun; Mayerich, DavidThis dissertation reports the use of in utero optical coherence tomography to evaluate changes in vasculature in a developing murine fetal brain caused due to prenatal exposure to teratogens. Embryogenesis is a highly complex process that is extremely vulnerable to external factors. Proper visualization of embryonic development is crucial to understand the basic physiological processes and identify defects if any. This dissertation is divided into two major sections: 1) assessing teratogen induced changes in the murine fetal brain vasculature during the second trimester equivalent period (chapters 2-4) and 2) combining optical coherence tomography with Brillouin microscopy to image and evaluate changes in biomechanical properties during neural tube closure in order to study first trimester exposure to teratogens (appendix A3). The first section is further divided into the following sub-sections: 1) assessing alcohol induced changes in murine fetal brain vasculature, 2) assessing nicotine induced changes in murine fetal brain vasculature, and 3) assessing synthetic cannabinoid (SCB) induced changes in murine fetal brain vasculature. The advancement of algorithms to image and detect minute changes in vasculature are also detailed. The contributions of this work are significant to understand the effects of teratogens on development, as blood flow plays a major role in embryogenesis. Understanding the acute changes in vasculature caused within minutes of maternal exposure to a teratogen can open several new avenues to explore as blood flow drives organ development. Results from this dissertation have been published in 7 first author peer-reviewed publications.Item Assessing the Vasculature Changes in Murine Fetal Brain Upon Alcohol Exposure(2017-10-12) Nguyen, Jennifer; Raghunathan, Raksha; Wu, Chen; Singh, Manmohan; Liu, Chih-HaoFetal Alcohol spectrum disorder (FASD) refers to a broad spectrum of abnormalities that arise due to prenatal alcohol exposure (PAE). The severity of the abnormality depends on the amount of alcohol consumed and period of consumption during gestation. A large number of women continue to consume alcohol even during the second trimester of pregnancy, a critical period for fetal neurogenesis and angiogenesis. OCT is an optical analog of ultrasound. 3D non-invasive imaging technique with high spatial resolution. OCT has shown to be extremely useful in embryonic imaging. Speckle variance OCT (SVOCT), is a functional extension of OCT that has been used to study vasculature development in embryos. We use SVOCT, to detect vasculature changes in the embryonic brain in utero, minutes after maternal alcohol consumption. The results show that there is a decrease in fetal vessel diameter within the first 10 minutes and it persisted for 45 minutes after maternal alcohol consumption, indicating that ethanol is a possible vasoconstrictor on the fetal brain. This project was completed with contributions from Rajesh C. Miranda from the Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center.Item Evaluating changes in murine fetal brain vasculature due to maternal nicotine exposure using in utero optical coherence tomography(2019) Mussio, Kelsey; Raghunathan, RakshaNicotine is a commonly used substance of abuse during pregnancy. Previous research has shown that prenatal nicotine exposure (PNE) is harmful to a fetus. PNE is known to cause intrauterine and postnatal growth restriction, decrease in head circumference and biparietal diameter, and perinatal mortality and morbidity. Evidence of negative influences of nicotine on brain development has been seen in humans too. It is unknown whether the relationship between maternal smoking and behavior problems is due to physical brain deficits caused by nicotine. In this study, we use optical coherence tomography (OCT), a noninvasive optical imaging modality with high spatial and temporal resolution to image the changes in fetal brain vasculature caused due to maternal nicotine exposure. We use a functional extension of OCT called correlation mapping optical coherence angiography (cm-OCA) to image microvasculature in the fetal brain, in utero. Pregnant mice at 14.5 days post coitum were anesthetized and placed on a heated surgical platform. Abdominal fur was removed, and a small incision was made to expose the uterine horn for imaging. After initial cm-OCA measurements, the mother was administered nicotine via intragastric gavage, at a dose of 1mg/kg. Subsequent measurements were taken for a period of 45 minutes at 5-minute intervals. A drastic decrease in parameters quantifying vasculature was seen within 45 minutes of maternal nicotine exposure during the second trimester equivalent period. This project was completed with contributions from Rajesh C. Miranda from Texas A & M University College of Medicine.