Showing papers by "University of Luxembourg published in 1984"

Rethinking Protoindustrialization and the Family

Abstract: Rethinking Protoindustrialization and the Family Protoindustrialization-the process of industrialization before the movement of large numbers of workers to factory employmenthas been of much interest to historians during the last two decades. With the pioneering work of Braun, the subsequent contributions of Mendels, Fischer, and Levine, and with the flowering of studies in the past few years, we have seen a great expansion of our understanding of the long process of European economic growth and its social and demographic consequences.1 Historians of the Industrial Revolution certainly never forgot the role played by rural manufacturing in the movement toward the factories which culminated in England in the last quarter of the eighteenth century. Nevertheless, the novelty of factory industrialization and the society which evolved in the nineteenth century did attract a great deal of attention. The social and demographic consequences of the nineteenth-century style of industry

Human red blood cells--an ideal model system for the action of calcium agonists and antagonists.

Abstract: To characterize the pharmacological properties of the slow calcium channel of human red blood cells, we studied the action of various calcium antagonists and two agonists on the 45Ca2+-influx. The Ca2+-ejecting ATPase was inhibited by vanadate. All dihydropyridine derivatives tested showed their inhibiting or stimulating effect on the channel at concentrations attainable in vivo (nitrendipine:Ki = 2.5; Bayer K 6244:Ki 5 microM; nicardipine:Ki = 15 microM, Ks = 0.5 microM; Ciba 28 392:Ki = 20, Ks = 0.3 microM; Ki = inhibition constant, Ks = stimulation constant). Of special interest was the biphasic behaviour (stimulation and inhibition) of the calcium antagonist nicardipine and the agonist Ciba 28 392. The maximum inhibition by the phenylalkylamine derivative verapamil was obtained at much higher concentrations (250 microM; Ki = 100). These data suggest that the calcium channel of human red blood cells has pharmacological properties very similar to the channel in heart and smooth muscle cells with respect to dihydropyridine action. Therefore, human red blood cells are an ideal model to study the action of calcium agonists and antagonists.

Nonequilibrium phase transitions with hysteresis in solid catalysts. The system copper-oxygen-propene

Abstract: The rates of formation of acrolein, CO2 and CO from propene and oxygen on oxides of copper as catalysts have been investigated at p = 50 mbar, 4 mbar ≤ p ≤ 200 mbar in a differential reactor at 645 and 735 K. Oxygen contents of the catalysts have been determined in situ by titration with H2 at 713 K. Selectivity and rate of oxygen consumption at steady state of the catalyst are not single valued functions of gas phase composition. Mainly the selectivity of acrolein formation follows a closed hysteresis-loop over a finite interval of p. This phenomenon can be understood as due to hysteresis in the phase transition between CuO and Cu2O under nonequilibrium conditions, which has been predicted by Wagner [1] on the basis of theoretical considerations. The results demonstrate that the steady state of a solid catalyst can be indeterminate for a given initial condition and a complete set of intensive variables describing the surroundings.

Cholesterol and its oxidized derivatives modulate the calcium channel in human red blood cells.

Abstract: The human red blood cell was used as a model system in order to study the effect of cholesterol and its medically important oxidized derivatives (OSC = oxidized sterol compounds) on the calcium entry channel. The calcium-ejecting adenosine triphosphatase (ATPase) was inhibited by vanadate and the influx of 45Ca2-into the cells measured. The cells were loaded with OSC at concentrations between 0.075 and 1.5 micrograms OSC/10(7) cells. Two classes of OSC could be distinguished: one stimulating Ca2+ influx dose-dependently by almost 100% at maximum concentrations, the other inhibiting it dose-dependently by up to 80%. The calcium channel blocker nitrendipine inhibited influx by 70% at 15 microM. More than 90% of the total stimulation or inhibition was accounted for by an influence on the nitrendipine-inhibitable part of influx, i.e. the calcium channel. Cholesterol (incorporated using liposomes) had a stimulatory (+288%), cholesterol depletion an inhibitory effect on calcium influx (-18%). These results demonstrate that cholesterol and its oxidized derivatives modulate the calcium channel in a highly stereospecific manner and provide new insights into the mechanism of action and the atherogenic effect of these compounds.