Hematology

Abstract:  Melatonin influences circadian rhythms and acts as antioxidant and free radical scavenger. UV irradiation triggers multiple cellular events which lead to cell death, in particular to apoptosis; this process involves reactive oxygen species. Apoptotic machinery involves several pathways, in which mitochondria play crucial roles. In this work we have evaluated by means of cytometric, biochemical and ultrastructural approaches, if incubation of U937 promonocytic leukemia cells with melatonin may affect apoptotic behavior induced by UV-B. The cell line was treated with 1 mm melatonin before and after UV-B exposure. Melatonin pretreatment significantly reduced the number of apoptotic cells, as revealed by FITC Annexin-V and propidium iodide assays (P < 0.005), as well as attenuated mitochondria alterations, as shown by ultrastructural morphology, Mito Tracker and JC-1 staining, and cytochrome c (cyt c) release (P < 0.005). On the contrary, incubation with melatonin after UV-B exposure significantly protect U937 cells from UV-B induced alterations, showing a possible delay of the apoptotic machinery (as revealed by the presence of earlier stages of apoptosis and significant cyt c release). Our results suggest that, in our experimental model, melatonin may play a role as noncytotoxic anti-apoptotic compound and, at least in part, may protect U937 cells from UV-B induced mitochondria dysfunction/damage.

Although it can be prevented, catheter-related bacteremia is common and dangerous. The antiseptics most widely used during insertion of peripheral venous catheters (PVCs) include povidone iodine, alcohol, and chlorhexidine. Another widely used antiseptic is a solution of 0.057 g sodium hypochlorite. This pilot study explored the contamination rate of the PVC tip inserted after skin decontamination with sodium hypochlorite. Culture analysis of the tips of the PVCs inserted into the 42 participants showed 7 (16.7%) colonized catheters. The results of this pilot study suggest taking into serious consideration the assessment of this antiseptic in randomized experimental studies.