Interactions between leukocytes, platelets and the endothelium in vein graft failure

Autologous venous grafts are preferred conduits in bypass surgery due to their length, easy harvesting, and feasibility. However, development of intimal hyperplasia decreases long-term patency rate in venous grafts prompting close clinical surveillance and further intervention. Mechanical forces, inflammation, and shear stress responses in venous grafts after surgical transfer may be involved in the development of intimal hyperplasia. This thesis focuses on inflammatory reactions in venous grafts. We hypothesized that interactions between leukocytes, platelets and endothelial cells induce intimal hyperplasia resulting in venous graft failure. We demonstrate that VGs obtained by end-to-end anastomosis of the inferior vena cava (IVC) from donor mice grafted to the abdominal aorta in recipients suffer extensive endothelial injury, platelet deposition and leukocyte invasion early after grafting. Re-endothelialization of interposed venous grafts was completed after 4 weeks. Regenerated endothelium displayed normal resistance to recruitment of leukocytes. Thus, we found that there is a time window during the first weeks following grafting in which venous grafts are susceptible to vessel injury and inflammation. Leukocyte recruitment on inflammatory endothelium initiates with margination, capture followed by rolling, firm adhesion and transmigration. We hypothesized that absence or functionblockage of leukocyte adhesion molecules P-selectin and E-selectin that are important for rolling may influence development of intimal hyperplasia in venous grafts by reduction of the recruitment of leukocytes. Indeed, intimal hyperplasia was significantly reduced in E- and P-selectin double deficient mice compared to WT both at 28 days and 63 days after VG transfer. This was paralleled by a reduction in the recruitment of leukocytes to the graft wall. Similar findings were made in WT mice treated with a combination of function-blocking antibodies against P- and E-selectin. The effect of P-selectin alone was addressed using P-selectin deficient mice. We found that intimal hyperplasia was significantly attenuated in mice deficient in P-selectin compared to WT mice 28 days after surgery concomitant with decreased leukocyte invasion. Interestingly, single-dose blockage of P-selectin or its leukocytic ligand PSGL-1 at the time of surgery could block the function of these molecules for up to 10 days and reduced later formation of intimal hyperplasia. Hence, early inhibition of these molecules has potential therapeutic effects on long-term vein graft failure. Platelets strongly influence haemostasis, inflammation and tissue regeneration after vascular injury, which are all represented in the period of re-endothelialization after venous graft transfer. We tested whether absence or function-blockage of platelets could influence intimal hyperplasia in venous grafts. We first used antiserum depletion of platelets for 12 days following surgical grafting. Indeed, IH and leukocyte invasion were reduced in platelet-depleted mice. Moreover, inhibition of integrin αIIbβ3, the main aggregation receptor on platelets, also reduced IH and leukocyte recruitment in the graft wall. The reduction of intimal hyperplasia in mice treated with the antibody against integrin αIIbβ3 was paralleled by radical reductions of the number of adherent platelets and leukocytes on the luminal surface of grafts one hour following grafting. In summary, our work emphasizes the role of interactions between leukocytes, platelets and the vessel wall in venous grafts during their adaptation to the arterial circulation. These mechanisms constitute attractive targets for the development of further preventive pharmacological strategies against vein graft failure

Ray-Trace of an Abnormal Radar Echo Using Geographic Information System

Weather radar plays a key role in natural disaster mitigation just as surveillance radar does in detecting objects that threaten homeland security. Both together comprise an instrumental part of radar observation. Therefore, quality control of the data gathered through radar detection is extremely important. However, radar waves propagate in the atmosphere, and an anomalous echo can occur if there are significant discontinuities in temperature and humidity in the lower boundary layer. The refractive curvature of the earth makes some errors in observation inevitable. On the night of July 3, 2003, Next Generation Radar (NEXRAD) weather radar detected an abnormal echo. The Weather Research and Forecast (WRF) model was utilized to simulate the atmospheric conditions. Radar propagation was simulated using the Advanced Refractivity Engineering Prediction System (AREPS) as well as the GIS. The results show the feasibility of establishing an abnormal propagation early-warning system and extending the application of the GIS in serving as the foundation of a Common Operation Picture (COP). Furthermore, the parameters of the boundary layer near the sea's surface in the numerical weather forecasting model need remodification.Defence Science Journal, 2009, 59(1), pp.63-72, DOI:http://dx.doi.org/10.14429/dsj.59.148

Senior women leaders in higher education overcoming barriers to success

The purpose of this study was to obtain a deeper understanding of what it takes for women to succeed as cabinet-level higher education administrators. The findings not only offer a wealth of strategies for career success and for overcoming professional and personal challenges, but also shed new light on critical factors that affect women’ experiences at work. This qualitative, phenomenological study was based primarily on confidential interviews with nine senior women leaders. Two informants are presidents, six are vice presidents, and one serves as a senior executive officer of their universities. Before assuming their current posts, they worked in a variety of leadership capacities ranging from department head to president at various institutions. All interviews were transcribed verbatim, analyzed, and compared for salient themes. To ensure the credibility of this research endeavor, triangulation was used by incorporating all informants and an independent outside auditor to validate the accuracy, objectivity, and plausibility of the results drawn from this study. Six major themes emerged from this research: effective leadership strategies: earning your place at the table; tests and trials; maintaining focus and political savvy; numbers matter: the rules change; gender as a two-edged sword; and competing as a woman: prepared and ready. The results revealed that to succeed as top-level executives, women must constantly overachieve, maintain good relationships with others, hold onto personal and institutional values to do the right things, expand themselves constantly, and utilize strong mentors’ assistance as well as sponsorship. When faced with implicit and explicit challenges such as unequal treatment, gender bias, resistance, political joggling, or personal struggles, they rely on private confrontation, emotional intelligence, and tenacity, as well as all possible support and resources to survive and thrive. The most important finding was the contrast between women leaders’ token experiences versus their experiences as an equal social group in leadership teams. The results confirmed Kanter’s (1993) theory about the impact of the proportion of women on management culture and on individual leaders’ experiences. Obviously, placing more women in powerful leadership positions will foster a more diversified, inclusive management culture and improve executive women leaders’ experiences at work

Invariants and Gorenstein projective modules

Invariants with respect to recollements of the stable category of Gorenstein projective A-modules over an algebra A and stable equivalences are investigated. Specifically, the Gorenstein rigidity dimension is introduced. It is shown that the Gorenstein rigidity dimension is invariant with respect to both Morita equivalences and the stable equivalences of Gorenstein projective modules. As a consequence, the Gorenstein rigidity dimension is shown the invariant of derived equivalences. The Gorenstein rigidity dimension is compared along the recollements of the stable category of Gorenstein projective modules. Moreover, the bounds of Gorenstein rigidity dimension is given for several classes of algebras, respectively.Comment: 8 page

Few-shot Open-set Recognition Using Background as Unknowns

Few-shot open-set recognition aims to classify both seen and novel images given only limited training data of seen classes. The challenge of this task is that the model is required not only to learn a discriminative classifier to classify the pre-defined classes with few training data but also to reject inputs from unseen classes that never appear at training time. In this paper, we propose to solve the problem from two novel aspects. First, instead of learning the decision boundaries between seen classes, as is done in standard close-set classification, we reserve space for unseen classes, such that images located in these areas are recognized as the unseen classes. Second, to effectively learn such decision boundaries, we propose to utilize the background features from seen classes. As these background regions do not significantly contribute to the decision of close-set classification, it is natural to use them as the pseudo unseen classes for classifier learning. Our extensive experiments show that our proposed method not only outperforms multiple baselines but also sets new state-of-the-art results on three popular benchmarks, namely tieredImageNet, miniImageNet, and Caltech-USCD Birds-200-2011 (CUB).Comment: Accpeted to ACM MM 202

Perinatal Hypoxic-Ischemic Encephalopathy

Perinatal hypoxic-ischemic encephalopathy (HIE) is an important cause of brain injury in the newborn and can result in long-term devastating consequences. Perinatal hypoxia is a vital cause of long-term neurologic complications varying from mild behavioural deficits to severe seizure, mental retardation, and/or cerebral palsy in the newborn. In the mammalian developing brain, ongoing research into pathophysiological mechanism of neuronal injury and therapeutic strategy after perinatal hypoxia is still limited. With the advent of promising therapy of hypothermia in HIE, this paper reviews the pathophysiology of HIE and the future potential neuroprotective strategies for clinical potential for hypoxia sufferers