The use of confocal microscopy in quantifying changes in membrane potential

Monitoring the plasma membrane potential and its changes can be a time consuming and challenging task especially when conventional electrophysiological techniques are used. The use of potentiometric fluorophores, namely tetramethylrhodamine methylester (TMRM), and digital imaging devices (laser scanning confocal microscopy) provides reliable and time efficient method. Two scorpion pore-forming peptides, namely PP and OP1, were used as a tool to induce depolarization of the plasma membrane potential of neuroblastoma cell line and cardiac myocytes. Alternative methods for the neuroblastoma cells and cardiac myocytes were used. Depolarization of the neuroblastoma cells was calibrated with 140 mM KCl solution with 1 µM valinomycin, after which intensity readers were substituted in the Nernst equation for quantification. Calibration of the alternative method used of the cardiac myocytes' plasma membrane potential changes was calibrated with the use of 5, 20, 40, and 80 mM KCl solutions with 1 µM valinomycin. A calibration curve was then constructed from which plasma membrane potential could be calculated

Cardiovascular control in space and on earth: The challenge of gravity

A total of five studies have been included in this work. The first two studies describe cardiovascular response changes to (simulated) microgravity in healthy subjects. In a third study, the circulatory response to standing is discussed in five cosmonauts before and after short-duration spaceflight. The last two studies deal with failing adaptive mechanisms of orthostatic blood-pressure control in patients who are prone to head-up tilt induced syncope. The team of Professor A. E. Aubert (F. Beckers, K. Couckuyt and J. Liu) from the Laboratory of Experimental Cardiology of the University Hospital in Leuven was involved in the completion of this thesis. Part of the work has been coordinated by Dr. W. Wieling (J. Gisolf and J.M. Karemaker) of the Academic Medical Center in Amsterdam and by Professor H. Ector (T. Reybrouck) of the Division of Clinical Cardiology in Leuven. © 2008 Elsevier Masson SAS. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Preeclampsia and toxic metals: a case-control study in Kinshasa, DR Congo.

BACKGROUND: Preeclampsia is frequent in Kinshasa (Democratic Republic of Congo), especially during the dry season. We tested whether preeclampsia was associated with exposure to environmental metals. METHODS: Using a case-control design, 88 women hospitalized with preeclampsia (cases) and 88 healthy pregnant women from the antenatal clinic (controls) were included in the study; 67 and 109 women were enrolled during the rainy and dry season, respectively. The concentrations of 24 elements were quantified by inductively coupled plasma mass spectrometry (ICP-MS) in 24-h urine collections. Differences in the urinary excretion of metals were investigated between cases and controls, and the interaction with season was assessed. RESULTS: Cases and controls were well matched regarding age, parity and duration of pregnancy. In controls, the urinary concentrations of most elements were substantially higher than reference values for adults from industrially developed countries, e.g. for lead: geometric mean (GM) 8.0 μg/L [25(th)-75(th) percentile 3.1-13.8]. The daily urinary excretions of 14 metals were significantly higher in women with preeclampsia than in control women, e.g. for lead: GM 61 μg/day (25(th)-75(th) percentile 8-345) in women with preeclampsia vs 9 μg/day (25(th)-75(th) percentile 3-21) in controls (p < 0.001). A significant interaction was found between season and preeclampsia for several elements, with higher urinary excretions in preeclamptic women than controls during the dry season, but not during the rainy season. CONCLUSIONS: This study revealed not only that women with preeclampsia excrete higher amounts of several toxic metals, especially lead, than control women, but also that this excretion exhibits seasonal variation, thus possibly explaining the high incidence and seasonal variation of preeclampsia in Kinshasa. Although the exact sources of this exposure are unknown, these findings underscore the need for preventing environmental exposures to lead and other toxic metals

Preeclampsia and toxic metals: a case-control study in Kinshasa, DR Congo

Preeclampsia is frequent in Kinshasa (Democratic Republic of Congo), especially during the dry season. We tested whether preeclampsia was associated with exposure to environmental metals.status: publishe