K-Electron-Capture-to-Positron-Emission Ratio in the Decays of ^(15)O and ^(19)Ne

The K/β^+ ratio in the decays of ^(19)Ne and ^(15)O have been measured as (9.6 ± 0.3) × 10^(-4) and (10.7 ± 0.6) × 10^(-4), respectively. A gas-flow proportional counter, operating in anticoincidence with the surrounding plastic scintillator, was used. Theoretical K/β^+ ratios for ^(19)Ne and ^(15)O were computed, using exchange-overlap corrections calculated by Vatai and, separately, exchange corrections extrapolated from the results of Bahcall for 14 ≤ Z ≤ 37. The experimental results were found to be in better agreement with Vatai's calculations

Differential sensitivity of basal and acetylcholine-induced activity of nitric oxide to blockade by asymmetric dimethylarginine (ADMA) in the rat aorta

<b>Background and purpose</b>: Previous work has shown that NG-monomethyl-l-arginine (l-NMMA) paradoxically inhibits basal, but not ACh-stimulated activity of nitric oxide in rat aorta. The aim of this study was to determine if the endogenously produced agent, asymmetric NG, NG-dimethyl-l-arginine (ADMA), also exhibits this unusual selective blocking action. <b>Experimental approach</b>: The effect of ADMA on basal nitric oxide activity was assessed by examining its ability to enhance phenylephrine (PE)-induced tone in endothelium-containing rings. Its effect on ACh-induced relaxation was assessed both in conditions where ADMA greatly enhanced PE tone and where tone was carefully matched with control tissues at a range of different levels. <b>Key results</b>: ADMA (100 µM) potentiated PE-induced contraction, consistent with inhibition of basal nitric oxide activity. Higher concentrations (300–1000 µM) had no greater effect. Although ADMA (100 µM) also appeared to block ACh-induced relaxation when it enhanced PE tone to maximal levels, virtually no block was seen at intermediate levels of tone in the presence of ADMA. Even ADMA at 1000 µM had no effect on the maximal relaxation to ACh, although it produced a small (two- to threefold) reduction in sensitivity. ADMA and l-NMMA, like l-arginine (all at 1000 µM), protected ACh-induced relaxation against blockade by l-NAME (30 µM). <b>Conclusions and implications</b>: In the rat aorta, ADMA, like l-NMMA, blocks basal activity of nitric oxide, but has little effect on that stimulated by ACh. Further studies are required to explain these seemingly anomalous actions of ADMA and l-NMMA

The ADMA/DDAH Pathway Regulates VEGF-Mediated Angiogenesis

Objectives— Asymmetrical dimethylarginine (ADMA) is a nitric oxide synthase (NOS) inhibitor and cardiovascular risk factor associated with angiogenic disorders. Enzymes metabolising ADMA, dimethylarginine dimethylaminohydrolases (DDAH) promote angiogenesis, but the mechanisms are not clear. We hypothesized that ADMA/DDAH modifies endothelial responses to vascular endothelial growth factor (VEGF) by affecting activity of Rho GTPases, regulators of actin polymerization, and focal adhesion dynamics. Methods and Results— The effects of ADMA on VEGF-induced endothelial cell motility, focal adhesion turnover, and angiogenesis were studied in human umbilical vein endothelial cells (HUVECs) and DDAH I heterozygous knockout mice. ADMA inhibited VEGF-induced chemotaxis in vitro and angiogenesis in vitro and in vivo in an NO-dependent way. ADMA effects were prevented by overexpression of DDAH but were not associated with decreased proliferation, increased apoptosis, or changes in VEGFR-2 activity or expression. ADMA inhibited endothelial cell polarization, protrusion formation, and decreased focal adhesion dynamics, resulting from Rac1 inhibition after decrease in phosphorylation of vasodilator stimulated phosphoprotein (VASP). Constitutively active Rac1, and to a lesser extent dominant negative RhoA, abrogated ADMA effects in vitro and in vivo. Conclusion— The ADMA/DDAH pathway regulates VEGF-induced angiogenesis in an NO- and Rac1-dependent manner

Economics of Tourism and Transport: An Introduction

No abstrac

A Novel Pathway for Metabolism of the Cardiovascular Risk Factor Homoarginine by alanine:glyoxylate aminotransferase 2

Low plasma concentrations of L-homoarginine are associated with an increased risk of cardiovascular events, while homoarginine supplementation is protective in animal models of metabolic syndrome and stroke. Catabolism of homoarginine is still poorly understood. Based on the recent findings from a Genome Wide Association Study we hypothesized that homoarginine can be metabolized by alanine:glyoxylate aminotransferase 2 (AGXT2). We purified human AGXT2 from tissues of AGXT2 transgenic mice and demonstrated its ability to metabolize homoarginine to 6-guanidino-2-oxocaproic acid (GOCA). After incubation of HepG2 cells overexpressing AGXT2 with isotope-labeled homoarginine-d4 we were able to detect labeled GOCA in the medium. We injected wild type mice with labeled homoarginine and detected labeled GOCA in the plasma. We found that AGXT2 knockout (KO) mice have higher homoarginine and lower GOCA plasma levels as compared to wild type mice, while the reverse was true for AGXT2 transgenic (Tg) mice. In summary, we experimentally proved the presence of a new pathway of homoarginine catabolism - its transamination by AGXT2 with formation of GOCA and demonstrated that endogenous AGXT2 is required for maintenance of homoarginine levels in mice. Our findings may lead to development of novel therapeutic approaches for cardiovascular pathologies associated with homoarginine deficiency

Sexuality and poverty: a case study of sex workers in Kampala, Uganda

The emerging focus on sexuality in development thinking has provided an opening for sex work issues to be included in the development framework. Unequal gender power relations restrict women’s employment opportunities and sex work becomes the best option out of very little choices. However, sexuality norms and beliefs have stratified sex work as ‘unacceptable’. As a result, sex workers face a wide range of challenges that prevent them from enjoying a full quality of life. This paper investigates the sex worker’s experience of poverty based on their unaccepted sexuality. Using the approach of poverty multidimensionality in the case of sex workers in Kampala, Uganda, it demonstrates that sexuality has an interactive relationship with poverty. It employs a combination of qualitative research methods to capture the lived experience of poverty

Margaret Chase Smith Library Student Essay Contest: Improving the American Educational System, First Place Essay

Each year, the Margaret Chase Smith Library sponsors an essay contest for high school seniors. In 2013, students were invited to propose what they would do to improve the American educational system

The impact of critical reflection on a private practice singing teacher's thinking

This situated self-as-researched investigation explores the impact of critical reflection on a private practice singing teacher’s thinking. The project is based upon the use of five ‘vehicles’ through which to develop the skills of critical reflection, these being journal writing, personal writing, critical incident technique, narrative inquiry and ideology critique. Each of these vehicles is used to undertake critical reflection of singing teaching practices whereby values and assumptions are interrogated. Each of the vehicles of critical reflection used in this inquiry is evaluated for their ease of use and effectiveness in enabling critical reflection processes to be developed in the participant. Engaging in critical reflection presents the possibility for transformative learning (Mezirow 1990) whereby frames of reference are challenged and altered as a result of the processes undertaken and examples of this in action are included in this research report. This dissertation contributes to the small but growing body of research in the area of private professional music education. The private instrumental and vocal teacher often works in an isolated environment with limited development opportunities available. This research proposes that critical reflection may be a viable tool for professional development and practice improvement