Fescue toxicosis is a common problem in beef cattle grazing endophyte-infected (E+) tall fescue. Symptoms include decreases in feed intake, weight gain, and reproductive efficiency along with vasoconstriction. The mechanisms by which fescue toxicosis affects the bovine reproductive tract have yet to be discovered. The objective of this study was to determine if the onset of fescue toxicosis conditions would alter the blood perfusion observed in the CL and peripheral concentrations of progesterone in cattle. We hypothesized that during fescue toxicosis, the vasoconstrictive symptoms would lead to a reduction in CL blood perfusion thus decreasing peripheral concentrations of progesterone. Overall, fescue toxicosis was induced as cows fed an E+ treatment diet had greater rectal temperatures and reduced pulse pressure and mean arterial pressure measurements; however, total blood perfusion of the CL and peripheral concentrations of progesterone did not differ in cattle under fescue toxicosis compared to those without.

This thesis provides insight into methods for estimating blood perfusion, emphasizing the need for accurate modeling in dynamic physiological environments. The thesis critically examines conventional error function solutions used in steady state or gradually changing blood flow scenarios, revealing their shortcomings in accurately reflecting more rapid changes in blood perfusion. To address this limitation, this study introduces a novel prediction model based on the finite-difference method (FDM) specifically designed to produce accurate results under different blood flow perfusion conditions. A comparative analysis concludes that the FDM-based model is consistent with traditional error function methods under constant blood perfusion conditions, thus establishing its validity under dynamic and steady blood flow conditions. In addition, the study attempts to determine whether analytical solutions exist that are suitable for changing perfusion conditions. Three alternative analytical estimation methods were explored, each exposing the common thread of inadequate responsiveness to sudden changes in blood perfusion. Based on the advantages and disadvantages of the error function and FDM estimation, a combination of these two methods was developed. Utilizing the simplicity and efficiency of the error function, the prediction of contact resistance and core temperature along with the initial blood perfusion was first made at the beginning of the data. Then the subsequent blood perfusion values were predicted using the FDM, as the FDM can effectively respond to changing blood perfusion values. / Master of Science / Blood perfusion, the process of blood flowing through our body's tissues, is crucial for our health. It's like monitoring traffic flow on roads, which is especially important during rapid changes, such as during exercise or medical treatments. Traditional methods for estimating blood perfusion, akin to older traffic monitoring techniques, struggle to keep up with these rapid changes. This research introduces a new approach, using a method often found in engineering and physics, called the finite-difference method (FDM), to create more accurate models of blood flow in various conditions. This study puts this new method to the test against the old standards. We discover that while both are effective under steady conditions, the FDM shines when blood flow changes quickly. We also examined three other methods, but they, too, fell short in these fast-changing scenarios. This work is more than just numbers and models; it's about potentially transforming how we understand and manage health. By combining the simplicity of traditional methods for initial blood flow estimates with the dynamic capabilities of the FDM, we're paving the way for more precise medical diagnostics and treatments.

This work represents the next step in the ongoing development of a system to noninvasively estimate blood perfusion using thermal methods. A combination thermocouple/thermopile sensor records heat flux and temperature measurements on the tissue of interest (in this case skin) for a given period of time. These data, in combination with other experimental parameters, are read into a computer program that compares them to a biothermal finite difference model of the system. The program uses an iterative process incorporating Gauss Minimization to adjust parameters in the biothermal model until the predicted system behavior satisfactorily approximates the real world data. The result is an estimation of blood perfusion in the tissue being measured, as well as an estimate of the thermal contact resistance between the probe and tissue. The system is tested on human forearms, canine legs during laparoscopic spay surgery, and on a canine medial saphenous fasciocutaneous free tissue flap model. Experimental measurements, especially those performed on the tissue flap model, show distinct correlation between blood perfusion and bioprobe output. This research demonstrates the accuracy of the biothermal model and the parameter estimation technique, as well as the usability of the system in a clinical setting. / Master of Science

Many medical therapies, such as thermal tumor detection and hypothermia cancer treatments, utilize heat transfer mechanisms of the body. The focus of this work is the development and experimental validation of a method to simultaneously estimate thermal conductivity, volumetric specific heat, and perfusion of in-vivo tissue. The heat transfer through the tissue was modeled using a modified Pennes' equation. Using a least-squares parameter estimation method with regularization, the thermal properties could be estimated from the temperature response to the known applied heat flux. The method was tested experimentally using a new agar-water tissue phantom designed for this purpose. A total of 40 tests were performed. The results of the experiments show that conductivity can be successfully estimated for perfused tissue phantoms. The values returned for volumetric specific heat are lower than expected, while the estimated values of perfusion are far greater than expected. It is believed that the mathematical model is incorrectly accounting between these two terms. Both terms were treated as heat sinks, so it is conceivable that it is not discriminating between them correctly. Although the method can estimate all three parameters simultaneously, but it seems that the mathematical model is not accurately describing the system. In the future, improvements to the model could be made to allow the method to function accurately. / Master of Science

My PhD research involves multi-disciplinary areas of study such as measuring perfusion of blood vessels in hamster dorsal skin using laser speckle imaging technique. In this study the changes were measured in blood flow velocity and diameters of micro vasculatures after the influence of glycerol application. The second study identifies the changes in morphology and optical properties of eye tissue after applying hyper-osmotic agent such as 100% anhydrous glycerol. Further investigation on the reversal process was performed without any application of 0.9% saline. The third study identified the variation in fluorescence in hamster dorsal skin tissue and enucleated porcine eyes with temperature. This study investigated the variation in fluorescence intensity with temperatures starting at 14°C and compared in vivo and in vitro results for consistency. The fourth study investigated an implantable drug delivery package that was fabricated using PMMA and implanted between the sub-conjunctival and super-scleral space and release the content of the device by either mechanical pressure or light-activated ophthalmic Nd:YAG laser after optically clearing the eye tissue by topical application of a hyper-osmotic agent, 100% anhydrous glycerol. A hyper-osmotic agent creates a transport region in the conjunctiva and sclera to get visual access of the compartments in the drug delivery package. This new technology would provide the option to the patient of one time implantation of the carrier system containing the drug. Each time the patient requires medication a ND-YAG or other laser beam will propagate through the cleared eye tissue to release the drug in measurable doses at the discretion of the doctor from the package directly in to the vitreous humor. In this study we have measured half-life of the dye in the vitreous humor or posterior chamber and biocompatibility. The last study had drawn distinction between the fluorescence signals based on the location (anterior or posterior chamber) of the 10% Na fluorescence dye in the in vivo rabbit and ex vivo pig eyes. / text

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21297号 / 医博第4386号 / 新制||医||1030(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 川口 義弥, 教授 妹尾 浩, 教授 羽賀 博典 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Assisted reproductive technologies such as estrus synchronization and embryo transfer can aid producers in meeting their goals of improving genetics, calve one calf per cow per year, and wean heavy calves. Most estrus synchronization protocols follow a GnRH-PGF-GnRH sequence. Ovulation prompted by exogenous gonadotropin releasing hormone (GnRH) may cause the release of sub-mature oocytes and lead to decreased pregnancy rates. Inclusion of estradiol benzoate (EB) improved pregnancy rates in some studies. The objective of this study was to determine if EB affects blood perfusion of follicles, corpus luteum (CL), or uterus, concentrations of estradiol and progesterone, or incidence of standing estrus.

A convenient method for testing and calibrating surface perfusion sensors has been developed. A phantom tissue model is used to mimic the non-directional blood flow of tissue perfusion. A computational fluid dynamics (CFD) model was constructed in Fluent to design the phantom tissue and validate the experimental results. The phantom perfusion system was used with a perfusion sensor based on the clearance of thermal energy. A heat flux gage measures the heat flux response of tissue when a thermal event (convective cooling) is applied. The blood perfusion and contact resistance are estimated by a parameter estimation code. From the experimental and analytical results, it was concluded that the probe displayed good measurement repeatability and sensitivity. The experimental perfusion measurements in the tissue were in good agreement with those of the CFD models and demonstrated the value of phantom tissue system. This simple, cost effective, and noninvasive convective blood perfusion system was then tested in animal models. The perfusion system was evaluated for repeatability and sensitivity using isolated rat liver and exposed rat kidney tests. Perfusion in the isolated liver tests was varied by controlling the flow of the perfusate into the liver, and the perfusion in the exposed kidney tests was varied by temporarily occluding blood flow through the renal artery and vein. The perfusion estimated by the convective perfusion probe was in good agreement with that of the metered flow of perfusate into the liver model. The liver tests indicated that the probe can be used to detect small changes in perfusion (0.005 ml/ml/s). The probe qualitatively tracked the changes in the perfusion in kidney model due to occlusion of the renal artery and vein. / Ph. D.

Blood perfusion is the local, non-directional blood flow through tissue. It is measured as the volumetric flow rate of blood through a given volume of tissue. One method that has been developed for measuring blood perfusion is a probe that measures the temperature response of the tissue when a thermal event is applied. From the temperature response, the blood perfusion and contact resistance can be estimated by comparing the experimental response to a predicted response, and employing Gaussian minimization techniques to estimate the blood perfusion and contact resistance. The objective of this research was to assess the measurement repeatability and sensitivity of the blood perfusion probe by testing the probe on phantom tissue, such that the effects of physiologic or pathologic conditions on the blood perfusion could be eliminated. Another objective was to conduct a preliminary in vivo study using rats for the purpose of establishing proper experimental protocols for future testing of the blood perfusion probe. A phantom tissue test stand comprised of porous material and water to simulate tissue and blood, respectively, was constructed for the phantom study. Inlet flow rates into the porous media ranging between 0 cc/min and 30 cc/min were tested. To test the measurement repeatability 7 flow rates (0, 5, 10, 15, 20, 25 and 30 cc/min) were tested on two different days. To test the measurement sensitivity of the probe, flow rates between 0 and 10 cc/min, and 15 and 20 cc/min were tested at intervals of 1 cc/min. From the phantom study it was concluded that the probe displayed good measurement repeatability, as the trend in perfusion as a function of inlet flow rates for both days was found to be the same. It was also found that the data collected using the probe yielded significantly different perfusion estimates for different flow rates, as statistical analyses show that the average perfusion differences between flow rates are truly independent within a 90% confidence interval, for flow differences above 4 cc/min. It was found that for flow rates below 4 cc/min the probe sensitivity was significantly reduced. For the in vivo study it was concluded that the probe can be used to obtain estimates of perfusion from rats. This preliminary study also served to establish proper experimental protocols for future tests. / Master of Science

A non-invasive blood perfusion system has been developed and tested in a phantom tissue and an animal model. The system uses a small sensor with a laminated flat thermocouple to measure the heat transfer response to an arbitrary thermal event (convective or conductive) imposed on the tissue surface. Blood perfusion and contact resistance are estimated by comparing heat flux data with a mathematical model of the tissue. The perfusion system was evaluated for repeatability and sensitivity using both a phantom tissue test stand and exposed rat liver tests. Perfusion in the phantom tissue tests was varied by controlling the flow of water into the phantom tissue test section, and the perfusion in the exposed liver tests was varied by temporarily occluding blood flow through the portal vein. The phantom tissue tests indicated that the probe can be used to detect small changes in perfusion (0.009 ml/ml/s). The probe qualitatively tracked the changes in the perfusion of the liver model due to occlusion of the portal vein. / Master of Science