Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 182-198).

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

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Kidney transplantation is the gold standard treatment for end-stage renal disease. Renal ischemia-reperfusion injury is an unavoidable consequence of the transplantation procedure and is responsible for delayed graft function and poorer long-term outcomes. Pharmacological inhibition of heat shock protein 90 is a preconditioning strategy that has previously been shown to reduce renal ischemia-reperfusion injury. However, the clinical application of heat shock protein 90 inhibitors is limited by their toxicity profile and the exact mechanisms of protection conferred are unknown. The aims of this thesis were to establish mechanisms of protection offered by these drugs and investigate a less toxic analogue that has the potential to be safely translated into human studies. AT13387 is a novel small molecule heat shock protein 90 inhibitor with a low toxicity profile, which is being evaluated in phase II studies in oncology and therefore has excellent translational potential in the context of transplantation. Heat shock protein 90 inhibition up-regulates protective heat shock proteins (especially heat shock protein 70) and potentially down-regulates NF-ҡB activity by disruption of the IҡB kinase complex. Toll-like receptor 4 is a further regulator of NF-ҡB activity and studies have suggested that Toll-like receptor 4 plays a dominant role in mediating kidney damage following ischemia-reperfusion injury. To explore potential molecular mechanisms of protection, human embryonic kidney cells were pre-treated with AT13387 and exposed to endotoxin-free hyaluronan to stimulate sterile Toll-like receptor 4-specific NF-ҡB activation. AT13387-treatment resulted in breakdown of IҡB kinase, which abolished Toll-like receptor 4-mediated NF-ҡB activation by hyaluronan. Inhibition of autophagy prevented IҡB kinase-α degradation by heat shock protein 90 inhibition and resulted in regain of NF-ҡB activity by hyaluronan. In subsequent investigations, AT13387 decreased pro-inflammatory cytokine release following hyaluronan stimulation and increased cell viability in an in vitro model of oxidative stress. In mice, AT13387 induced heat shock protein 70 expression in the kidney. AT13387 pre-treatment then significantly reduced kidney injury following renal ischemia-reperfusion injury. In contrast, in severe combined immunodeficient mice, AT13387 no longer reduced kidney injury from renal ischemia-reperfusion injury. This emphasises the potential importance of the adaptive immune system in the protective effect of this agent. This resonates with reports of heat shock protein 70 up-regulation in the context of heat preconditioning, which leads to renal protection from renal ischemia-reperfusion injury that is lymphocyte-dependent. Secondary lung injury is an additional consequence of renal ischemia-reperfusion injury. In further experiments, pre-treatment with AT13387 again did not reduce kidney injury following renal ischemia-reperfusion injury in severe combined immunodeficient mice. However, AT13387 did reduce secondary lung injury. This lung protective effect may have been related to heat shock protein 70 up-regulation in the lungs by AT13387. A rationale for enhancing recovery, following renal ischemia-reperfusion injury, by inhibiting heat shock protein 90 was then sought. This investigation was undertaken in order to broaden the range of the available therapies to a wider group of patients including renal transplant recipients. AT13387 pre-treatment of the recipient mice preceded an isograft renal transplantation with a kidney harvested from a treatment naive mouse and cold stored for 4 hours. Although a significant reduction in tubular necrosis was not demonstrated following AT13387 treatment, the feasibility of the treatment strategy was demonstrated and interestingly lung injury secondary to transplantation was reduced. This thesis therefore highlights AT13387 as a new agent with the potential of reducing kidney injury and secondary lung injury following renal ischemia-reperfusion injury. The findings also demonstrate that the mechanisms of protection offered by this drug may involve the adaptive immune system. In addition to the induction of heat shock protein 70 expression in the kidney and repression of Toll-like receptor 4-mediated NF-ҡB signalling through breakdown of IҡB kinase.

Heart transplantation is often the only therapeutic option for patients with end stage heart disease. Allograft organs are in short supply. Thus, preserving the life of a grafted organ is extremely important. Cardiac allograft vasculopathy (CAV) is an expression of chronic rejection that accounts for the greatest loss of graft function in transplanted hearts. Peri-transplant ischemia/reperfusion (I/R)-injury occurs during transplantation when blood flow is stopped to remove the heart from the donor and then is reinstated upon implantation of the donor heart into the recipient. This oxidative injury contributes to vascular dysfunction and CAV. In this dissertation, I hypothesize that prevention and/or reduction of I/R during transplantation reduces post-transplant vascular dysfunction and CAV. In this regard, myself and my colleagues examined the roles of apoptosis repressor with caspase recruitment domain (ARC) and cytochrome p450 (CYP) 2C enzymes in UR-induced vascular dysfunction and CAV. ARC expression was detected in endothelial cells (ECs) and smooth muscle cells (SMCs); however, increased levels of ARC do not protect against oxidant injury. ARC overexpression did protect against oxidant-induced cell death in H9c2 rat embryonic myoblasts. We observed that ARC-overexpression prevented H9c2 differentiation into muscle cells. With our focus on vascular injury, we turned our attention to the CYP 2C enzymes. Both endothelium-dependent and independent vascular function was impaired following I/R. Pre-treatment with the CYP 2C inhibitor sulfaphenazole (SP) restored endothelial sensitivity to acetylcholine, but did not restore sensitivity to endothelium-independent vasodilators. Rat heterotopic heart transplants were performed with rats being treated with SP or vector control prior to surgery. Rats treated with SP showed significantly reduced luminal narrowing and had decreased SMC proliferation, oxidant and interferon-y levels. No differences were detected in immune infiltration or apoptosis. Complementary studies in cultured vascular cells revealed that CYP 2C9 expression decreased viability and increased ROS production following hypoxia and re-oxygenation in ECs but not in SMCs. In summary, we did not detect protection of vascular cells by ARC, but did discover a novel role for ARC in differentiation. CYP 2C contributes to post-ischemic vascular dysfunction and CAV through increased oxidative stress and endothelial dysfunction. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

BACKGROUND: Strategic limb occlusion applied after exercise (PEIC) may expedite recovery, not just in directly affected tissue, but over the entire body via circulating factors. METHODS: Twenty active college-age males took part in a single-blind randomized crossover design. Participants underwent intervention and SHAM treatments after strenuous exercise sessions. Peak Torque production and soreness measures were gathered directly before and 24-hours after two exercise sessions. STATISTICAL ANALYSES: A 2 x 2 repeated measures analysis of variance with sidak corrections (significance of p<0.05) was used to analyze peak torque and VAS scores. RESULTS: Significance was not observed between any associated pre- and post-peak torque test (p > 0.05). Post-treatment VAS scores were statistically higher than pre-treatment for all conditions except pre-and post-intervention in the direct leg (P = 0.096). DISCUSSION: The application of PEIC was not associated with any significant differences in peak torque production or soreness measures.

Ischemic events of even a very short duration are not tolerated Ill in humans. The human cost of ischemia, when looked at as combined cardiovascular disease, dwarfs all other causes of death in the United States. Annually, CVD kills as many people in the US as does cancer, chronic lower respiratory disease, accidents, and diabetes mellitus combined. In 2005 (the latest year for which final statistics are available), CVD was responsible for 864,480 deaths or 35.3 percent of total deaths for the year. In my study, I have used the nematode Caenorhabditis elegans to determine genetic and environmental modulators of oxygen deprivation a key component of ischemia. I have found that animals with mutations in insulin like signaling pathways, neuronal function, electron transport chain components, germline function, and animals that are preconditioned by being raised on a diet of E. coli HT115 bacteria at 25°C have an enhanced ability to survive long-term (>72 hours) anoxia (<.005 kPa O2) at 20°C. The enhanced anoxia survival phenotype partially correlates with increased levels of carbohydrate stores in the nematodes. Suppression of this enhanced anoxia survival phenotype is possible by altering expression of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, the FOXO transcription factor DAF-16, and 5’-AMP kinase.

BACKGROUND: Oxygen therapy has been widely used for a variety of systemic conditions. The ischemic basis of many ocular conditions provides a basis for oxygen’s application in this area as well. REVIEW: Literature was reviewed to evaluate the efficacy of oxygen therapy in treating inner retinal ischemia (diabetic retinopathy, vein occlusions, artery occlusions, and radiation retinopathy), outer retinal ischemia (retinal detachment, macular holes, and macular degeneration), nerve ischemia (ischemic optic neuropathy, diabetic papillopathy, and ischemic third nerve palsy), and ocular ischemia (ocular ischemic syndrome and retinopathy of prematurity). Published studies support the use of oxygen for a range of ocular conditions including diabetic retinopathy, retinal detachments, and macular holes. For other conditions where autoregulation may limit flow during hyperoxia, isocapnic hyperoxia provides a method to circumvent these limitations. METHODS: One radiation retinopathy patient received a three-hour normobaric hyperoxia trial. Oxygen was delivered by an oxygen concentrator through a face mask at a rate of five liters per minute. Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity, contrast sensitivity, intraocular pressure, and optical coherence tomography testing were obtained immediately preceding and following the trial to determine any changes. RESULTS: The results show slightly improved ETDRS visual acuity and contrast sensitivity score. Retinal edema in the area of greatest thickness showed a decrease of 3.1%, a larger change than would be expected in a healthy, control eye. CONCLUSIONS: The results of the three-hour normobaric hyperoxia trial suggest that oxygen is effective in reducing retinal edema. Visual acuity was not impacted as greatly, but that may be a result of the specific presentation of this radiation retinopathy patient. / 2021-06-14T00:00:00Z

Indiana University Purdue University Indianapolis / H2S is a gaseous mediator that acts as an anti-inflammatory agent contributing to gastrointestinal mucosal defense. It promotes vascular dilation, mucosal repair, and resolution of inflammation following intestinal ischemia and may be exploited as a novel therapeutic agent. It is unclear if H2S works through nitric oxide-dependent pathways in the intestine. We appreciated that H2S was able to improve post-ischemic recovery of mesenteric perfusion, mucosal integrity, and inflammation. The beneficial effects of H2S appear to be mediated through endothelial nitric oxide-dependent pathways.

This study was aimed at characterizing the apoptotic response equine small intestine subjected to experimental ischemia-reperfusion injury and determining if use of an angiotensin converting enzyme inhibitor (enalaprilat) would ameliorate the apoptotic response. It was designed to determine if mucosal epithelial cells undergo apoptosis during the ischemia phase and also examined if apoptosis is significantly exacerbated by reperfusion. It also investigated whether administration of enalaprilat decreased reperfusion injury secondary to reduced enterocyte apoptosis. Injury was induced using a low flow model of I-R. During celiotomy a single loop of jejunum was isolated and arterial flow decreased to 20% of baseline for one hour and complete occlusion for a second hour. Reperfusion was monitored for 3 hours. A control group (n=6) were not treated while the treatment group (n=6) received 0.5 mg/kg enalaprilat in 0.9% NaCl immediately following ischemia. Jejunal samples were taken prior to the induction of ischemia, immediately post-ischemia and at 1, 2 and 3 hours of reperfusion. Samples were evaluated for gross tissue pathology with standard hematoxylin and eosin staining, the presence of apoptotic cells via TUNEL staining, and gene expression of three apoptosis related genes (bax, bcl-2, p53) using qPCR. Serum enalaprilat and ACE concentrations were determined from blood samples drawn concurrent with jejunal sampling using HPLC/MS and standard HPLC. Plasma enalaprilat concentrations were comparable to previous reports in awake horses. Enalaprilat appeared to have no effect on serum ACE concentrations, however a significant spike in ACE concentration occurred in the treatment group at 1 hour of reperfusion (P=0.0001). Grade of mucosal damage was not significantly different between control and treatment groups at any time point. Subjectively apoptotic index appeared to be higher in the treatment group at end ischemia and during reperfusion. There were no changes in expression of p53 or bcl-2 in either group. Bax expression was significantly decreased (P= 0.02) in the control group at 2 hours of reperfusion. Based on our data administration of an ACE inhibitor during anesthesia in horses with an ischemic segment of intestine confers no protective benefit and may be associated with increased intestinal injury and apoptosis. Lack of expression of p53, bax and bcl-2 suggests another apoptotic mechanism in equine ischemic intestine. / Master of Science