Effect of modern pacing algorithms on generator longevity: a predictive analysis.

Pulse generator (PG) longevity is of major importance to the quality of care of pacemaker patients. A series of automatic algorithms affect PG longevity. This study investigated the individual and combined effects of three algorithms incorporated in the Medtronic Kappa 700 pacemaker series: Capture Management periodically measures the stimulation threshold and adjusts the PG output, Sinus Preference allows the sinus rate to prevail in a specified range below the sensor rate, and Search AV allows an extension of the AV interval if spontaneous conduction is observed.

Enhancement of adriamycin toxicity by iron chelates is not a free radical mechanism.

The possible involvement of metal ions and free radicals in the cytotoxic mechanism of Adriamycin (ADR) was investigated, using a model system of Escherichia coli cells. It is shown that E. coli mediated the production of free radicals under anaerobic (ADR-semiquinone) and aerobic (superoxide) conditions.

Ferritin uptake by human erythroid precursors is a regulated iron uptake pathway.

Iron delivery to mammalian cells is traditionally ascribed to diferric transferrin (Tf). We recently reported that human erythroid precursor cells possess specific membranes receptors that bind and internalize acid isoferritin. Here we show that ferritin uptake by these cells is highly regulated and that the internalized ferritin-iron is used for home synthesis and thus, this process could constitute a physiological pathway for iron assimilation.

Sites and mechanisms of low-level oxidative stress in cultured cells.

Oxidative stress is involved in a multitude of pathological conditions. In the present study, we investigated the cellular targets and the mechanisms of low-level oxidative stress in a Chinese Hamster Ovary cell culture. Oxidative stress was induced either by continuous enzymatic production of superoxide or by bolus addition of hydrogen peroxide (H2O2).

Ferritin does not accumulate iron oxidized by caeruloplasmin.

Ferritin is an iron-storage protein ubiquitous in mammals, plants and bacteria. It can be reconstituted, in vitro, from the apoprotein and Fe(II) salts in the presence of dissolved oxygen. Recently it has been reported that caeruloplasmin can facilitate apoferritin reconstitution and that iron oxidized by caeruloplasmin is sequestered within the ferritin shell.