by Manabu Ueda. / Title from cover. "July 1998." / Includes bibliographical references (p. [22]-[23]).

Sepsis has deleterious effects on cardiac function including reduced contractility. We have shown previously that lipopolysaccharides (LPS) directly affect HL-1 cardiac myocytes by inhibiting Ca2+ regulation and by impairing pacemaker "funny" current, If. We now explore further cellular mechanisms whereby LPS inhibits excitability in HL-1 cells. LPS (1 jxg/ml) derived from Salmonella enteritidis decreased rate of firing of spontaneous action potentials in HL-1 cells, and it increased their pacemaker potential durations and decreased their rates of depolarization, all measured by whole cell current clamp. LPS also increased action potential durations and decreased their amplitude in cells paced at 1 Hz with 0.1 nA, and 20 min were necessary for maximal effect. LPS decreased the amplitude of a rapidly inactivating inward current attributed to Na+ and of an outward current attributed to K+; both were measured by whole cell voltage clamp. The K+ currents displayed a resurgent outward tail current, which is characteristic of the rapid delayed-rectifier K+ current, Ikr. LPS accordingly reduced outward currents measured with pipette Cs+ substituted for K+ to isolate Ikr. E-4031 (1 (xM) markedly inhibited Ikr in HL-1 cells and also increased action potential duration; however, the direct effects of E-4031 occurred minutes faster than the slow effects of LPS. We conclude that LPS increases action potential duration in HL-1 mouse cardiomyocytes by inhibition of Ikr and decreases their rate of firing by inhibition of Ina. This protracted time course points toward an intermediary metabolic event, which either decreases available mouse ether-a-go-go (mERG) and Na+ channels or potentiates their inactivation.

Die Visualisierung bisher nicht nachweisbarer Defekte in hochwertigem Silizium konnte durch die Entwicklung neuer hochempfindlicher Mikrowellendetektionsverfahren erreicht werden. Dies eröffnet eine Vielzahl von Möglichkeiten zur kontaktlosen und zerstörungsfreien Charakterisierung von Halbleitern. Insbesondere sind bisher unzugängliche Defekte in Silizium und selbst in dünnen epitaktischen Schichten nachweisbar. Elektrische Eigenschaften von Halbleitern wie Lebensdauer, Beweglichkeit und Diffusionslänge können bei kleinen Injektionsraten mit einer Ortsauflösung, die nur durch die Diffusionslänge der Ladungsträger limitiert ist, gemessen werden. Aufgrund der um mehrere Größenordnungen verbesserten Empfindlichkeit kann über ein Mikrowellenabsorptionssignal die Ladungsträgeremission aus Defekten selbst bei qualitativ hochwertigstem Silizium untersucht werden. Dies ermöglicht die Vorhersage elektrischer Eigenschaften von Bauelementen bereits an den Ausgangswafern.