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Induced Bradycardia Effects on Angiogenesis, Growth and Development in Early Development in Chicken Embryos, Gallus Domesticus

Description: Cardiac performance, angiogenesis and growth was investigated during early chicken development. Heart rate, and thus arterial pulse pressure and cardiac output, were altered with the bradycardic drug ZD7288. Heart rates at 72 h of development of control embryos and those dosed with chicken Ringer were not different at 171 bpm. Acute and chronic application of ZD7288 caused significant bradycardia. Chronic dosing of Ringer and ZD7288 changed neither eye diameter nor development rate. Chronic dosing of ZD7288 did not significantly alter CAM vessel density close to the embryo (2, 3 and 4 mm) but at farther distances (5 and 6 mm) chronic dosing with both Ringer and ZD7288 decreased vessel density by 13 - 16%. Chronic dosing with ZD7288 also reduced body mass by 20%. Thus, lowered heart rate and cardiac output had little effect on vessel density or developmental stage, but did reduce embryo growth.
Date: December 2010
Creator: Ruck, Sylvia A.
Partner: UNT Libraries

Water-soluble Phosphors for Hypoxia Detection in Chemical and Biological Media

Description: Water-soluble Pt(II) phosphors exist predominantly for photophysical studies. However, fewer are known to be candidates for cisplatin derivatives. If such a molecule could exist, it would be efficient at not only destroying the cancerous cells which harm the body, but the destruction would also be traceable within the human body as it occurred. Herein, research accomplished in chemistry describes the photophysical properties of a water-soluble phosphor. Spectroscopically, this phosphor is unique in that it possesses a strong green emission at room temperature in aqueous media. Its emission is also sensitive to the gaseous environment. These properties have been expanded to both analytical and biological applications. Studies showing the potential use of the phosphor as a heavy metal remover from aqueous solutions have been accomplished. The removal of toxic heavy metals was indicated by the loss of emission as well as the appearance of a precipitate. The gaseous sensitivity was elicited to be used as a potential cancerous cell biomarker. In vivo studies were accomplished in a wide variety of species, including bacteria (E. coli), worms (C. elegans), small crustaceans (Artemia), and fish (D. rerio and S. ocellatus). The phosphor in question is detectable in all of the above. This fundamental research lays the foundation for further expansion into bioinorganic chemistry, and many other possible applications.
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Date: December 2012
Creator: Satumtira, Nisa Tara
Partner: UNT Libraries

Cardio-Respiratory Ontogeny and the Transition to Bimodal Respiration in an Air Breathing Fish: Morphological and Physiological Development in Normoxia and Hypoxia.

Description: As selection pressures exist for not only adults, but for every life history stage, it is important to understand how environmental factors shape developing animals. Despite the significance placed on aquatic hypoxia as a driving force in the evolution of air breathing, this is the first known study to examine the effects of hypoxia on cardio-respiratory ontogeny of an air breathing fish. Blue gouramis are obligatory air breathing fish that possess a labyrinth-like structure that serves as the air breathing organ. Gouramis were reared for up to 90 d in normoxia or hypoxia, and morphological and physiological development was observed. Hypoxic larvae had increased lamellar and labyrinth organ surface areas. Bradycardia and increased gill ventilation rates were observed when larvae from either rearing group were briefly exposed to hypoxia. Hypoxic larvae also showed a reduced heart rate and gill ventilation rate in the absence of a hypoxic stimulus, possibly indicative of a more comprehensive, long-term respiratory plasticity. The similarity of routine oxygen consumption between rearing groups suggests that metabolic demand did not change for hypoxic larvae, but that they were more efficient at oxygen acquisition. This is further supported by increased resistance time of hypoxic gouramis to extreme hypoxia. The onset of air breathing was between 20 and 25 d post-fertilization, and was not affected by either rearing or exposure environment. It may be that this behavior is associated with the inability of smaller larvae to successfully overcome water surface tension, rather than with the necessity of aerial respiration at this stage. Hypoxia is commonly experienced by most air breathing fishes, and studies of hypoxia-induced developmental effects may provide critical insights into the evolution of air breathing. The studies presented here provide novel data on the plasticity of cardio-respiratory development of an air breathing fish reared in hypoxia, and can ...
Date: August 2009
Creator: Blank, Tara M.
Partner: UNT Libraries

Metabolic, cardiac and ventilatory regulation in early larvae of the South African clawed frog, Xenopus laevis.

Description: Early development of O2 chemoreception and hypoxic responses under normoxic (150 mmHg) and chronically hypoxic (110 mmHg) conditions were investigated in Xenopus laevis from hatching to 3 weeks post fertilization. Development, growth, O2 consumption, ventilatory and cardiac performance, and branchial neuroepithelial cells (NEC) density and size were determined. At 3 days post fertilization (dpf), larvae started gill ventilation at a rate of 28 ± 4 beats/min and showed increased frequency to 60 ± 2 beats/min at a PO2 of 30 mmHg. Also at 3 dpf, NECs were identified in the gill filament buds using immunohistochemical methods. Lung ventilation began at 5 dpf and exhibited a 3-fold increase in frequency from normoxia to a PO2 of 30 mmHg. Hypoxic tachycardia developed at 5 dpf, causing an increase of 20 beats/min in heart rate, which led to a 2-fold increase in mass-specific cardiac output at a PO2 of 70 mmHg. At 10 dpf, gill ventilatory sensitivity to hypoxia increased, which was associated with the increase in NEC density, from 15 ± 1 to 29 ± 2 cells/mm of filament at 5 and 10 dpf, respectively. Unlike the elevated rate, cardiac and ventilatory volumes were independent of acute hypoxia. Despite increased cardioventilatory frequency, larvae experienced an average of 80% depression in during acute hypoxia. Chronic hypoxia (PO2 of 110 mmHg) decreased mass-specific cardiac performance before 10 dpf. In older larvae (10 to 21 dpf), chronic hypoxia decreased acute branchial and pulmonary hypoxic hyperventilation and increased NEC size. Collectively, these data suggest that larvae exhibit strong O2-driven acute hypoxic responses post-hatching, yet are still O2 conformers. All acute hypoxic responses developed before 5 dpf, and then the effects of chronic hypoxia started to show between 7 and 21 dpf. Thus, the early formation of acute hypoxic responses is susceptible to the environment and can ...
Date: December 2009
Creator: Pan, Tien-Chien
Partner: UNT Libraries