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The aim of this study was to evaluate the effects of pulsed, extremely low-frequency electromagnetic fields (ELF-EMF) on in-vitro mouse pre-antral follicle development. Pre-antral follicles were cultured for 5 days and exposed to ELF-EMF at the frequencies of 33 or 50 Hz. ELF-EMF application did not affect follicular growth over a 3 day culture period, but on day 5 the growth of 33 Hz-exposed follicles was significantly reduced when compared with controls, while the 50 Hz-exposed follicles were not significantly affected. However, ELF-EMF severely impaired antrum formation at both frequencies, as 79 +/- 3% of control follicles developed antral cavities compared with 30 +/- 6% and 51.6 +/- 4% of 33 or 50 Hz-exposed follicles respectively. The follicles with failed antrum formation showed lower oestradiol release and granulosa cell DNA synthesis, but these effects were not related to granulosa cell apoptosis. Furthermore, a high percentage of the in-vitro grown oocytes obtained from exposed follicles had a reduced ability to resume meiotic maturation when compared with controls. These results suggest that ELF-EMF exposure might impair mammalian female reproductive potentiality by reducing the capacity of the follicles to reach a developmental stage that is an essential pre-requisite for reproductive success. [ABSTRACT FROM AUTHOR]

Paramagnetic nitroxides have been proposed as probes in electron paramagnetic resonance (EPR) imaging and in clinical diagnosis. However, nitroxides are rapidly reduced in vivo to hydroxylamines, diamagnetic EPR-inactive species. Reduction occurs in blood via soluble agents such as ascorbic acid, as well as in the cells via enzymatic and non-enzymatic endocellular systems. To prevent the reduction, a water soluble nitroxide, i.e., potassium peroxylamine disulfonate, is entrapped in reverse phase evaporation vesicles. The loaded liposomes have a high entrapment capacity, and vesicles with the encapsulated agent are stable for days, even at room temperature. The vesicles in vitro can almost completely prevent the reduction of the entrapped nitroxide by ascorbic acid. In blood of a rat, enriched with a homogenate of rat liver proteins, the vesicles are able to greatly prolong the life time of the nitroxide. In particular, the encapsulated nitroxide has a half-life of more than one hour, compared to two minutes for free nitroxide under the same conditions. Due to these protective effects, the lipid vesicles might be useful as a delivery system for paramagnetic agents. [ABSTRACT FROM AUTHOR]

The valence-band discontinuity ΔEv has been determined for the (100) GaSb/AlSb strained-layer heterojunction with a room-temperature lattice mismatch of 0.65%, using x-ray photoemission core level spectroscopy. For 30 Å epitaxial layers of AlSb grown on GaSb, the measured valence-band offset was ΔEv=0.40±0.15 eV. The reverse growth sequence consisting of a thin GaSb layer grown on an AlSb buffer exhibited the same valence-band offset, indicating that for the (100) oriented heterojunction ΔEv is not strongly affected by the growth sequence. [ABSTRACT FROM AUTHOR]