Thesis (M. Phil.)--University of Queensland, 2002. / Includes bibliographical references.

vii, 169 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Surgery, 1975

Control of blood flow to skeletal muscle is essential to maintain the overall homeostasis of an organism. The primary route that skeletal muscle uses to accommodate an increased metabolic demand associated with physical activity is to increase its blood flow through functional hyperemia. The importance of functional hyperemia in ensuring proper skeletal muscle function spurred 130 years of investigation into the mechanism(s) regulating its occurrence.Despite not identifying the essential factor(s) for controlling skeletal muscle blood flow, the last century of investigation has uncovered much about the process; including the observation that skeletal muscle functional hyperemia is impaired with ischemic disease. In patients, this can result in immobility, chronic ulcerations, gangrene, and at worst, amputation. To develop efficacious therapies, we as scientists must develop a better understanding of the molecular mechanisms underlying impaired vascular function during ischemia.The goal of this work was to lay the foundation for investigations examining the role of specific gene products involved in modulating blood flow control during ischemic revascularization by assessing vascular function in the mouse following an ischemic event. Unique among research animals, the mouse is routinely accessible for targeted genetic disruption, which allows investigators to assess the requirement of specific gene-products in a physiological process. Unfortunately, to date, no publication that I am aware of describes blood flow measurement to contracting mouse skeletal muscle following an ischemic/revascularization event. Therefore, the primary objective of this work was to assess vascular function in genetically unaltered animals.I found that unlike other species thus far examined, vascular dysfunction is not an obligatory response to hindlimb ischemic revascularization in the mouse. Ex vivo vasodilation responses to acetylcholine were statistically significantly impaired in the muscular branch artery 14 days following an ischemic event. However, using a newly developed fluorescent microsphere-based approach for determining skeletal muscle blood flow, I found that functional hyperemia was similar for the gracilis posterior muscle between non-ischemic and day-14 ischemic animals. In light of the primary literature, these findings suggest that vascular growth, and not ischemia per se is the primary regulator of vascular function during health and disease.

Thesis (PH.D.) -- University of Adelaide, Dept. of Surgery, 1975.

No description available.

The aim of this study was to determine the trends in protocol, success rates, and consistency in follow up of revascularization procedures in a controlled environment. Patients of the Virginia Commonwealth University School of Dentistry were identified who were offered revascularization therapy as a treatment option on immature permanent teeth from January 1, 2010 to May 31, 2017. A total of 77 patients and 78 teeth were evaluated for revascularization therapy. For patients accepting treatment, records were reviewed for outcome assessment and consistency of follow up. A total of 30 patients (31 teeth) were treated following revascularization protocols, with only 20 patients (21 teeth) returning for follow up. Six of the 21 teeth needed some form of additional therapy due to patients remaining symptomatic, however 15/21 exhibited varying levels of success. Recall rate was 67.7%. With a success rate of 71.4%, revascularization therapy should continue to be considered for all patients with teeth having necrotic pulps and immature root apices. However, changes to recall protocols need to be improved in order to better monitor the status of teeth that undergo revascularization therapy.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Limb and digit loss poses a significant problem across the animal kingdom. Ambystoma mexicanum, commonly known as the axolotl, however, is one species that has achieved a remarkable ability to bypass the misfortune associated with a lost limb. Viewed as a model organism in regenerative studies, the axolotl retains extraordinary regenerative properties well into adulthood that humans severely lack. While the basics of regeneration have been described, much about the molecular processes of regeneration is still largely unknown. Thrombospondin-1 (TSP-1), an angiogenesis inhibitor, has been identified as a potential factor to play a significant role in the regrowth of limbs. Vascularization of tissues is vital to the survival of biological structures, and TSP-1 has been shown to play a regulatory role in the development and remodeling of tissue vasculature. Here, we study the effect of a loss-of-function mutation in the tsp-1 gene on the process of limb regeneration in the axolotl. Our studies reveal that tsp-1 -/- animals lag in regeneration time, developing smaller blastemas in the first three weeks of regeneration. We show that the loss of TSP-1, however, is not deleterious to the overall process of regeneration as late stage blastemas of the -/- animals catch up in size and development to the wild type animals after three weeks. Our data suggests that while TSP-1 may be important during the initial stages, it may not be required for proper regeneration.

Submitted in partial fulfilment of the requirements for the Degree of Masters in Technology: Clinical Technology, Durban University of Technology, 2009. / Currently, off-pump coronary artery bypass surgery (OPCAB) is a selectively employed technique for myocardial revascularization used in the majority of heart units worldwide. This strategy obviates the documented deleterious effects of cardiopulmonary bypass. However the occurrence of neurological sequelae associated with OPCAB ranges from minor cognitive dysfunction to major stroke. Haemodynamic instability throughout the positioning, stabilization and interruption of coronary blood flow are regarded as important factors that affect the performance of off-pump surgery. Fluctuations during the perioperative period, in particular manipulation of the heart could result in temporary brain hypoperfusion and neurological sequelae. To predict those patients that are predisposed to cerebral complications, investigators have used neurological monitoring, in particular Near-infra red spectroscopy (NIRS) during cardiac surgery. Aims and Objectives of the study This prospective, observational study was carried out to assess the correlation between cerebral oxygen saturation and central venous saturation during OPCAB surgery. Central venous saturation is an important variable used to assess global tissue perfusion and could therefore be advocated as a surrogate measure of cerebral oxygen saturation. In addition variables such as mean arterial (MAP) pressure, heart rate (HR), patient oxygen saturation (SpO2), partial pressure of carbon dioxide (PcvCO2), haematocrit (Hct) and lactate were also measured to determine if they were independent predictors of cerebral desaturation. This study is one of the first done in the South African population group. iv Methodology Twenty patients undergoing OPCAB surgery from the Cardiothoracic unit at Inkosi Albert Luthuli Central Hospital, Durban, South Africa were recruited in the trial. Cerebral somasensors were placed on the patients forehead to measure left and right cerebral saturations. These sensors were linked by cables to the cerebral monitor (NIRS), INVOS model 5100C. Eight time periods throughout the surgical procedure whereby patients would be haemodynamically unstable were identified. These time periods included, post induction and pre sternotomy, pre and post placement of swabs beneath the heart, pre and post placement of the stabilizer device (Octopus), pre and post snaring of the LAD (left anterior branch of the coronary arteries), pre anastomosis and during anastomosis of the coronary arteries, second sample during anastomosis and post anastomosis, pre and post removal of swabs from beneath the heart, pre and post transfer of the patient to the ICU bed. These time periods constituted the sampling period pre and post manoeuvres. Eight paired measurements, i.e., MAP, PaCO2, HR, Hct, lactate, SpO2, central venous saturation (ScvO2) and cerebral oxygen saturation (rSo2) per patient were taken during these time periods. Recording of cerebral saturations and blood samples from the central venous line were taken during these eight time periods in order to determine the correlation between central venous and cerebral oxygen saturations. Results Strong positive correlations between central venous saturation and cerebral saturation presented in majority of the sampling time periods throughout the study (post induction and pre sternotomy, post placement of swabs beneath the heart, post snaring of the LAD (left anterior branch of the coronary arteries, pre anastomosis and during anastomosis of the coronary arteries, second sample during v anastomosis, pre and post transfer of the patient to the ICU bed). The positive correlation indicates that central venous saturation can be used as a surrogate measure of cerebral oxygen saturation during OPCAB surgery. Conclusion The absence or poor correlation of MAP, HR, PcvCO2, heamatocrit, lactate, and patient saturation to cerebral saturation in this study suggests that insertion of a central venous line (CVP) during OPCAB should be a fundamental clinical requirement.

Submitted in partial fulfilment of the requirements for the Degree of Doctor of Technology: Clinical technology, Durban University of Technology, 2011. / Surgical revascularization of the coronary arteries is a cornerstone of cardiothoracic surgery. The enduring nature of coronary artery bypass grafting (CABG) bespeaks of its history and proven efficacy. However, cerebral deoxygenation during on-pump coronary artery bypass graft surgery may be associated with adverse neurological sequelae. Advanced age and the incidence of preoperative co-morbidity in patients presenting for coronary artery bypass graft surgery increases the potential for stroke and other adverse perioperative outcomes (Murkin, Adams, Quantz, Bainbridge and Novick, 2007). It is hypothesized, that by using the brain as an index organ, interventions to improve cerebral oxygenation would have systemic benefits for cardiac surgical patients. In an attempt to predict those patients that are predisposed to cerebral complications, investigators have used neurological monitoring ie, Near infrared spectroscopy (NIRS) to enhance detection of hypoxic conditions associated with neurological injury (Hoffman, 2006). Serum S100B protein has been used as a biochemical marker of brain injury during cardiac surgery. Elevated levels serve as a potential marker of brain cell damage and adverse neurological outcomes (Einav, Itshayek, Kark, Ovadia, Weiniger and Shoshan, 2008). Aims and Objectives of the study This prospective, quantitative, interventional study was carried out to maintain cerebral tissue oxygen saturation during cardiopulmonary bypass above 75% of the baseline level by implementation of a proposed interventional protocol. The analysis of S100B which is a marker of neurological injury and optimization of regional cerebral oxygen saturation would allow for the formulation of an algorithm which could be implemented during on-pump coronary artery bypass graft surgery as a preventive clinical measure further reducing the risk of neurological injury. Central venous lines (CVP) are inserted routinely during cardiac surgery. Central venous oxygen saturation is a global marker of tissue oxygenation. A secondary aim of the study was to determine if a correlation existed between central venous and cerebral tissue oxygen saturations. If a positive correlation existed then central venous oxygen saturation could be used as a surrogate measure of cerebral tissue oxygen saturation during on-pump coronary artery bypass graft surgery. This study is one of the first done in the South African population group. Methods Forty (40) patients undergoing on-pump coronary artery bypass graft surgery were recruited at Inkosi Albert Luthuli Central Hospital. Patients were randomized into a control group (n=20) and interventional group (n=20) using a sealed envelope system. The envelope contained designation to either group. Envelopes were randomly chosen. Intraoperative regional cerebral oxygen saturation (rSO2 ) monitoring with active display and treatment intervention protocol was administered for the interventional group. In the control group regional cerebral oxygen saturation monitoring was not visible to the perfusionist operating the heart lung machine during cardiopulmonary bypass (blinded). Recording of regional cerebral saturation was conducted by an independent person (another perfusionist) who was not involved in the management of the case so as to ensure that no interventions were carried out on the control group. Arterial blood samples for the measurement of serum S100B were taken pre and postoperatively. An enzyme immunoassay (ELISA) was used for the quantitative and comparative measurement of human S100B concentrations for both groups. Central venous oxygen saturation was monitored from the CVP using the Edwards Vigileo monitor. Cerebral monitoring constituted the use of Near infrared spectroscopy monitoring using the Invos 5100c, Somonetics Corp, Troy MI monitor. Adhesive optode pads were be placed over each fronto- temporal area for cerebral oxygen measurement. During cardiopulmonary bypass, eight time period measurements of mean arterial pressure (MAP), heart rate, temperature, activated clotting time (ACT), patient oxygen saturation (SpO2), partial pressure of carbon dioxide (pCO2), haematocrit, lactate, pH, haemoglobin (Hb), base excess (BE), potassium (K+), sodium (Na+), glucose, calcium (Ca2+), central venous oxygen saturation (ScvO2), cerebral tissue oxygen saturation (rSO2), fraction inspired oxygen (FiO2 ), sweep rate, pump flow rate (cardiac index), and percentage isoflurane per patient were taken. The time periods when data was recorded included: 5 minutes after onset of cardiopulmonary bypass, aortic cross clamping, after cardioplegic arrest, during distal anastomosis, during proximal anastomosis, during rewarming, after aortic cross clamp release and before termination of cardiopulmonary bypass. Baseline measurements were also taken. Clinical data recorded for both groups included: the number of grafts performed, cardiopulmonary bypass time, cross clamp time, red blood cells administered (packed cells), amount of adrenalin infused and total cerebral desaturation time. A prioritized intraoperative management protocol to maintain rSO2 values above 75% of the baseline threshold during cardiopulmonary bypass was followed. Cerebral desaturation was defined as a decrease in saturation values below 70% of baseline for more than one minute. Interventions commenced within 15 seconds of decrease below 75% of baseline value. Results The results of the study show that there was a highly significant difference in the change in S100B concentrations pre and post surgery between the interventional and control groups. The intervention vii group showed a smaller increase in S100B concentration of 37.3 picograms per millilitre (pg/ml) while the control group showed a larger increase of 139.3 pg/ml. Therefore, the control group showed a significantly higher increase in S100B concentration over time than the intervention group (p < 0.001). Maximizing pump flow rates was the most common intervention used (45 times) followed by maintaining partial pressure of carbon dioxide to approximately 40 mmHg (28 times), increasing mean arterial pressure by administration of adrenalin (11 times) and administration of red blood cells to increase haematocrit (11 times). There was a highly statistically significant treatment effect within the intervention group for each of the above interventions compared with no intervention. The above mentioned interventions significantly affected right and left cerebral oxygen saturations. However, administration of red blood cells was not found to significantly increase right (p = 0.165) and left (p = 0.169) cerebral oxygen saturation within the intervention group. The study highlighted a significant difference between the intervention and control groups in terms of cerebral desaturation time (p <0.001). The mean desaturation time for the control group was 63.85 minutes as compared to 24.7 minutes in the interventional group. Cerebral desaturation occurred predominantly during aortic cross clamping, distal anastomosis of coronary arteries and aortic cross clamp release. Predictors of cerebral oxygen desaturation included, partial pressure of carbon dioxide (pCO2), temperature, pump flow rate (LMP), mean arterial pressure (MAP), haematocrit, heart rate (HR) and patient oxygen saturation (SpO2). Central venous oxygen saturation was not significantly related to right (p = 0.244) or left (p = 0.613) cerebral oxygen saturations. Therefore central venous oxygen saturation cannot be used as a surrogate measure of cerebral tissue oxygen saturation during on-pump coronary artery bypass graft surgery. viii Conclusion These findings demonstrate the positive effect of optimizing cerebral oxygen saturation using an interventional protocol on markers of neurological injury (S100B). Optimization of pump flow rate, partial pressure of carbon dioxide and mean arterial pressure would result in increased cerebral oxygen saturation levels and a reduction in neurological injury. Therefore, an algorithm incorporating these interventions can be formulated. Monitoring specifically for brain oxygen saturation together with an effective treatment protocol to deal with cerebral desaturation during on-pump CABG must be advocated.