Duquesne University

About: Duquesne University is a education organization based out in Pittsburgh, Pennsylvania, United States. It is known for research contribution in the topics: Population & Health care. The organization has 3615 authors who have published 7169 publications receiving 180066 citations. The organization is also known as: Duquesne University of the Holy Spirit.

Sulfite Oxidase Catalyzes Single-Electron Transfer at Molybdenum Domain to Reduce Nitrite to Nitric Oxide

Abstract: Aims: Recent studies suggest that the molybdenum enzymes xanthine oxidase, aldehyde oxidase, and mARC exhibit nitrite reductase activity at low oxygen pressures. However, inhibition studies of xanthine oxidase in humans have failed to block nitrite-dependent changes in blood flow, leading to continued exploration for other candidate nitrite reductases. Another physiologically important molybdenum enzyme—sulfite oxidase (SO)—has not been extensively studied. Results: Using gas-phase nitric oxide (NO) detection and physiological concentrations of nitrite, SO functions as nitrite reductase in the presence of a one-electron donor, exhibiting redox coupling of substrate oxidation and nitrite reduction to form NO. With sulfite, the physiological substrate, SO only facilitates one turnover of nitrite reduction. Studies with recombinant heme and molybdenum domains of SO indicate that nitrite reduction occurs at the molybdenum center via coupled oxidation of Mo(IV) to Mo(V). Reaction rates of nitrite to N...

Developmental diversity of amphibians

Abstract: The current model amphibian, Xenopus laevis, develops rapidly in water to a tadpole which metamorphoses into a frog. Many amphibians deviate from the X. laevis developmental pattern. Among other adaptations, their embryos develop in foam nests on land or in pouches on their mother's back or on a leaf guarded by a parent. The diversity of developmental patterns includes multinucleated oogenesis, lack of RNA localization, huge non-pigmented eggs, and asynchronous, irregular early cleavages. Variations in patterns of gastrulation highlight the modularity of this critical developmental period. Many species have eliminated the larva or tadpole and directly develop to the adult. The wealth of developmental diversity among amphibians coupled with the wealth of mechanistic information from X. laevis permit comparisons that provide deeper insights into developmental processes. WIREs Dev Biol 2012, 1:345–369. doi: 10.1002/wdev.23 For further resources related to this article, please visit the WIREs website.

Microglial/Macrophage polarization and function in brain injury and repair after stroke.

Abstract: Stroke is a leading cause of disability and mortality, with limited treatment options. After stroke injury, microglia and CNS-resident macrophages are rapidly activated and regulate neuropathological processes to steer the course of functional recovery. To accelerate this recovery, microglia can engulf dying cells and clear irreparably-damaged tissues, thereby creating a microenvironment that is more suitable for the formation of new neural circuitry. In addition, monocyte-derived macrophages cross the compromised blood-brain barrier to infiltrate the injured brain. The specific functions of myeloid lineage cells in brain injury and repair are diverse and dependent on phenotypic polarization statuses. However, it remains to be determined to what degree the CNS-invading macrophages occupy different functional niches from CNS-resident microglia. In this review, we describe the physiological characteristics and functions of microglia in the developing and adult brain. We also review (a) the activation and phenotypic polarization of microglia and macrophages after stroke, (b) molecular mechanisms that control polarization status, and (c) the contribution of microglia to brain pathology versus repair. Finally, we summarize current breakthroughs in therapeutic strategies that calibrate microglia/macrophage responses after stroke.

Student Perceptions of Teacher Support and Competencies for Fostering Youth Purpose and Positive Youth Development: Perspectives From Two Countries

Abstract: With the growing interest in the development of purpose in youth, one important role that requires attention is the school teacher. The current article explores student perceptions of the role teachers can play in fostering purpose in their students in the mid- and late adolescent years, and the teacher competencies that facilitate purpose development. The present investigation posits and tests a structural model in which student perceptions of teacher support predicts youth purpose, mediated by student perceptions of teacher competencies; in turn, youth purpose predicts broader positive youth development. Two samples of demographically diverse young people ages 13–18 were surveyed in the United States (n = 381) and Finland (n = 336). Results showed support for the role of teachers in fostering purpose, and provided evidence for the hypothesized model with some cross-cultural differences. Implications of these findings for developing purpose in schools are discussed.

Striking differences in cellular catalase activity between two DNA repair-deficient diseases: xeroderma pigmentosum and trichothiodystrophy.

Abstract: Xeroderma pigmentosum (XP) and trichothiodystrophy (TTD) are two recessively transmitted human diseases characterized by DNA repair deficiency. While XP is associated with a very high incidence of cancer on skin exposed to sunlight, TTD is not a cancer-prone disease. Therefore, unrepaired UV-induced DNA lesions do not appear to be enough to give rise to tumors. In order to understand the differences between these two syndromes, we measured catalase activity in cellular extracts, UV irradiated or not, and quantified H2O2 production following in vitro UV irradiation. We confirmed on 21 different XP diploid fibroblast lines that catalase activity was decreased on average by a factor of five as compared to controls, while XP heterozygote lines exhibited intermediary responses. All seven TTD lines we tested were deficient in UV-induced lesion repair and exhibited a high level of catalase activity. However, molecular analysis of catalase transcription showed no difference between normal, XP and TTD cell lines. This was confirmed by Western blots where the amount of catalase subunits was identical in all cell lines studied. Finally, UV irradiation induces five and three times more H2O2 production in XP lines compared with TTD or controls respectively. These striking differences between TTD and XP indicate that UV light, directly or indirectly, together with defective oxidative metabolism may increase the initiation and/or the progression steps in the XP environment compared to TTD. This may partly explain the different tumoral phenotype observed between the two diseases.