No abstract

Background/Aims: Hydrazone and acylhydrazone derivatives, which are produced from aldehyde reacting with hydrazine or acylhydrazine, have been reported to exhibit antitumor activities. However, the angionenic effects of this kind of derivatives haven’t been elucidated. Here, we synthesized 12 pyridoxal hydrazone and acylhydrazone compounds and investigated their antiangiogenic effects and the underlying mechanisms. Method: 3-(4,5-Dimethylthiazol-2-yl)-2, 5-dipheyltetrazolium bromide assay was used to screen the inhibitory effects of the synthesized compounds on endothelial cells (ECs) proliferation. The compound with best inhibitory effect was further evaluated with wound-healing assay and tube formation assay. Calcein-Am assay was carried out to determine the content of intracellular labile iron pool (LIP). Intracellular reduced glutathione (GSH) was determined by spectrophotometry. Flow cytometry was used to determine cell cycle and apoptosis. Results: Compound 10 (3-hydroxy-5-[hydroxymethyl]-2-methyl-pyridine-4-carbaldehyde-2-naphthalen-1-acetyl hydrazone) showed the best inhibitory effect on human umbilical vascular ECs proliferation, with IC50 value of 25.4 μmol/L. It not only inhibited wound-healing and tube formation of ECs, but also decreased the content of intracellular LIP and GSH. Furthermore, it arrested ECs cycle at S phase and induced cell apoptosis. Conclusions: Compound 10 exhibits antiangiogenic effects by reducing the content of intracellular LIP and GSH, and subsequently arresting cell cycle and inducing cell apoptosis.

This paper looks at the influence of financial factors on the labour market transitions of Canadian older workers. Also, in contrast to previous studies, the analysis focuses on transitions between full-time work, part-time work, and retirement. Sequential annual observations of employment and retirement choices are examined for samples of full-time and part-time workers, drawn from the Survey of Labour and Income Dynamics (SLID), 2001–2006. Measures of potential pension wealth and one-year and peak pension accruals are imputed using data from the Survey of Consumer Finances, 1973–1997, and the SLID, 1997–2006. Regression results indicate that financial factors influence workers to move from full-time to part-time jobs and support the evidence found in previous studies that retirement is usually a process, not a single event. Also, an increase in pension accruals increases the probability of working full-time for lower-income earners only. Among nonfinancial factors, a negative health shock increases the probability of working part-time or retiring for full-time workers but has little effect on the labour market transitions of part-time workers. Finally, these results suggest that policies to encourage phased retirement are unlikely to have a significant labour market effect since bridge employment is already a common transition process among older workers.