Leukocyte adhesion to cerebral endothelial cells plays a critical role in the inflammatory response following transient global cerebral ischemia but its contribution to delayed neuronal cell death is not completely understood. We compared ischemic mice treated with a monoclonal antibody to β2-integrin adhesion receptors (anti-CD18) or a non-binding control antibody following ischemia. Inflammation was characterized by increased CD18 expression on leukocytes and inflammatory mediators in the peripheral blood and brain tissue. Notably, interleukin-1β, which has been shown to mediate cell death in neurons, was elevated in the blood and brain. Anti-CD18 blocked leukocyte adhesion as well as the inflammatory responses, including interleukin-1β expression in neurons. Blocking leukocyte adhesion protected the structural integrity of the hippocampus, cerebral cortex and thalamus, and preserved spatial. Leukocytes adhesion to endothelial cells plays an important role in the evolution of neurological deficit in global cerebral ischemia despite the lack of transmigration of leukocytes across blood-brain-barrier.

Necrotizing enterocolitis (NEC), a severe inflammatory disorder of the gastrointestinal tract with high morbidity and mortality, affects primarily preterm infants. The diagnosis represents a challenging task, and no biomarker has been found to aid early diagnosis with high accuracy. Microdialysis has been widely used to detect metabolites of anaerobic metabolism, enabling a local and early detection of ischemia. This thesis aims to evaluate the possibility of detecting intestinal ischemic stress in experimental and clinical  NEC, by use of rectal intraluminal microdialysis. Intraluminal rectal microdialysis was performed on rats subjected to total intestinal ischemia. Metabolites of ischemia were detectable in both ileum and rectum, with raised glycerol concentrations and lactate/pyruvate ratios. Elevated concentrations of glycerol correlated to increasing intestinal histopathological injury. Experimental early NEC was induced in newborn rat pups, by hypoxia/re-oxygenation treatment. Development of NEC was confirmed by histopathology. Elevated glycerol concentrations were detected by rectal microdialysis. The genetic alterations following experimental NEC in rat pups were studied with microarray. Immunohistochemistry staining was performed for tight junction proteins claudin-1 and claudin-8. Several genes were altered in experimental NEC, mainly genes regulating tight junctions and cell adhesion. Immunohistochemistry revealed reduced expression of claudin-1. A prospective study was conducted on preterm infants with a gestational age of less than 28 weeks. The infants were admitted to a neonatal intensive care unit, and observed during a 4-week period. Rectal microdialysis was performed twice a week, and blood was drawn for analysis of I-FABP. A total of 15 infants were included in the study, whereof four infants developed NEC, and 11 served as controls. Rectal glycerol and I-FABP displayed high concentrations, which varied considerably during the observation periods, both in NEC and controls. No differences in either glycerol or I-FABP concentrations were seen in the NEC-group vs. the controls. In conclusion, rectal microdialysis can detect metabolites of intestinal ischemia, both in experimental and clinical NEC. Rectal microdialysis is safe and could provide a valuable non-invasive aid to detect hypoxia-induced intestinal damage or ischemic stress in extremely preterm infants. In this study however, it was not possible to predict the development of clinical NEC using microdialysis or I-FABP.

Since caloric restriction (CR) can modify multiple pathways central to the ischemic cascade and enhance neuroplasticity mechanisms, we hypothesized that CR should exert protective effects following brain ischemia. Previous studies have suggested benefit when CR was administered prior to ischemia. This study investigated whether prolonged CR beginning after global ischemia would result in lasting protection as assessed by performance in the open field, as a measure of functional outcome, and hippocampal CA1 neuronal counts. Adult male Mongolian gerbils were subjected to five minute bilateral carotid artery occlusion (I) or sham surgery (S) with tympanic temperature maintained at 36.5 ± 0.2ºC during the intra-ischemic period. After screening out gerbils with incomplete ischemia, each of the two surgical groups were randomly assigned to control diet (CON) or 30% CR for the duration of the study (60d). Gerbils were tested in the open field on d3, 7, 10, 30 and 60. Ischemic animals on control diet showed a significantly higher level of activity in the open field (impaired habituation) compared to SCON gerbils on all test days (p<0.001). Open field activity was decreased 9% in the ICR group versus ICON gerbils on d7 (p=0.024), suggesting a transient neuroprotective effect. Open field activity of the SCR gerbils began increasing relative to that of SCON gerbils during the last 30 days of the study (p=0.055 on d60), raising the question of suitability of the open field test for long-term studies of CR and ischemia. Brain sections obtained at d60 were stained with hematoxylin & eosin. Hippocampal CA1 neuron counts were reduced 88% by ischemia (p<0.001), and there was no sparing effect of CR. These findings suggest that prolonged CR administered beginning after global ischemia cannot diminish brain injury or enhance long-term recovery.

Blood vessel growth is mediated by angiogenesis, which is defined as the formation of new blood vessel out of existing vessels, as well as vasculogenesis, a process that circulating progenitor cells contributes to adult neovascularization. Cilostazol, a commercially available drug holding antiplatelet and vasodilating effects, increases intracellular cyclic adenosine monophosphate (cAMP) levels through inhibiting the activity of phosphodiesterase 3. Interestingly, this chemical compound has a lot of cellular effects. In current work, we demonstrated that cilostazol promoted proliferation and migration of human umbilical cord vein endothelial cells (HUVECs), enhanced in-vitro vascular tube formation, and increased releasing of cAMP and NO from them. Furthermore, cilostazol activated eNOS and PI3-K/Akt signaling pathways. We also examined the angiogenic and vasculogenic effects of cilostazol in a murine hindlimb ischemia model. Our data showed that cilostazol enhanced angiogenesis and vasculogenesis with resultant flow recovery after murine hindlimb ischemia partly mediated by promoting mobilization of bone marrow-derived stem cells into circulation and increasing in situ expression of some proteins involved in angiogenesis. In addition, cilostazol significant increased colony forming unit of human endothelial progenitor cells. These results are unique and clinically significant with potential in translational therapy. According to our report, further preclinical and clinical studies of cilostazol on the other ischemic situations such as myocardial infarction will be justified.

Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: NMR; diffusion coefficient; cerebral ischemia; diffusion weighted imaging. Includes bibliographical references.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Dec. 9, 2009). "College of Education." Includes bibliographical references (p. 84-88).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Ependymin; anti-oxidative enzyme SOD. Includes bibliographical references (p. 65-69).

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

Stroke is a serious cerebral vascular event and a leading cause of death and disability worldwide, and ischemic stroke is the most common type. Evidence from animal research in acute cerebral ischemia shows that a combination of neuroprotectants might be more efficacious than the single agent given individually. Both melatonin and electro-acupuncture (EA) have been suggested to be effective treatments against cerebral ischemia. However, it is unknown whether a combination of these two therapies could be beneficial against focal cerebral ischemia. In the first study, the effect of post-treatment with a combination of melatonin and EA on regional cerebral blood flow (rCBF), neurological deficit score and infarct volume was investigated in both permanent and transient middle cerebral artery occlusion (MCAO) models in rats. When compared with the single treatment of melatonin or EA, the combination therapy resulted in a significant improvement of neurological function and a dramatic reduction of infarct volume at 72 hr after transient MCAO. A significant upregulatory effect on rCBF has been exerted by the combined treatment. The effect of a combination of melatonin and EA on inflammatory reaction was investigated in the second study. Post-treatment of the combination therapy effectively inhibited neutrophil infiltration as well as the expression of some pro-inflammatory mediators, and increased the anti-inflammatory protein expression at 72 hr after transient MCAO. This beneficial effect may be due to the respective anti-inflammatory effects of melatonin and EA. In the third study, the effect of a combination of melatonin and EA on apoptosis was examined. When compared with the EA treatment alone, post-treatment of the combination therapy exerted a greater inhibitory effect on tissue apoptosis and expression of the pro-apoptotic proteins as well as an upregulatory effect on the anti-apoptotic protein expression. In the fourth study, the effect of continuous post-treatment of a combination of melatonin and EA on transient MCAO was investigated. The combination treatment significantly improved neurological function and decreased infarct volume at 7 days after transient MCAO. Cell proliferation and expression of the neurotrophic factor were increased by the combined treatment. The effect of pretreatment with a combination of melatonin and EA was examined in the fifth study. Neurological function was improved and infarct volume was reduced by the combination pretreatment at 24 hr after transient MCAO. The inflammatory and apoptotic reaction were inhibited by the combined pretreatment through the modulatory effect of the related proteins. In summary, our results show that, when compared with the single treatment of either melatonin or EA, post-treatment with a combination of melatonin and EA induced a complementary neuroprotective effect on improvement of neurological function and a dramatic reduction of infarct volume after transient MCAO. The complementary protection may be partially mediated via anti-inflammation and anti-apoptosis after transient cerebral ischemia. Pretreatment with a combination of melatonin and EA may be more effective in preventing ischemic brain injury after transient focal cerebral ischemia. / published_or_final_version / Medicine / Doctoral / Doctor of Philosophy