Epitestosterone and testosterone have similar nonclassical actions on membrane of Sertoli cells in whole seminiferous tubules.

Epitestosterone is the 17α-epimer of testosterone. This steroid possesses antiandrogenic activities. The mechanism of action of epitestosterone has not been elucidated. The aim of this study was to investigate the nonclassical effect of epitestosterone on the membrane of Sertoli cells in proliferative phase (rats aged 15 days) and in nonproliferative phase (rats aged 21 and 35 days). The membrane potential of Sertoli cells was recorded using a standard single microelectrode technique. Epitestosterone (0.5, 1, and 2 µM) or testosterone (1 µM) was administered alone and after infusion with flutamide (1 µM), verapamil (100 µM), or U-73122 (2 µM). The testes of rats aged 12-15 days were preincubated with 45Ca2+ with or without flutamide (1 µM) and incubated with epitestosterone (1 µM) or testosterone (1 µM). Epitestosterone and testosterone produced a depolarization in the membrane potential and increased the membrane input resistance on Sertoli cells from rats of all 3 ages. The effect of epitestosterone did not change after perfusion with flutamide. Epitestosterone increased 45Ca2+ uptake within 5 min and this effect was not inhibited by flutamide. The absence of an effect by flutamide suggests that epitestosterone acts independently of the intracellular androgen receptor. The depolarizing effect was inhibited by verapamil, a voltage-dependent calcium channel blocker, and by U-73122, a phospholipase C inhibitor. These results indicate that epitestosterone acts on the membrane via a nonclassical signaling pathway; the effect was similar to the testosterone action on membrane of Sertoli cells in whole seminiferous tubules from rat testes.

Design and characterization of a liquid-crystal spatial light modulator for a polarization-insensitive optical space switch.

We report preliminary results concerning a free-space optical switch between single-mode fibers with a ferroelectric liquid-crystal (FLC) spatial light modulator (SLM). In particular, we show experimentally that such a device can operate in a polarization-insensitive manner. The influence of the geometrical and physical features of the FLC SLM on the overall performance of the optical fiber switch are also discussed.

Node-based reconfigurable volume interconnections. 1. Principles and optical design.

We present a general-purpose three-dimensional interconnection network that models various parallel operations between two data planes. This volume interconnection system exhibits reconfigurable capabilities because of parallel and externally weighted interconnection modules, called nodes. We propose a generic optical implementation based on the cascading of two planar hologram arrays, coupled with a bistable optically addressed spatial light modulator. The role of this component is discussed in terms of energy regeneration and spatial cross-talk limitation. As an example, a binary matrix-matrix multiplier is implemented that uses a ferroelectric liquid-crystal light valve.

Node-based reconfigurable volume interconnections. 2. Hologram encoding considerations.

We address free-space optical interconnections based on cascaded multifacet holographic elements, including an intermediate regeneration of the optical signals. Particular attention is paid to digital hologram encoding in the case of highly interconnected planes. Degrees of freedom selected in the reconstruction plane are used for satisfying both holographic-encoding and signal constraints. An iterative Fourier-transform algorithm is chosen because of its ability to incorporate constraint considerations.

Recording reconfigurable binary computer-generated holograms on bistable optically addressed ferroelectric liquid-crystal spatial light modulators.

The capacity of optically addressed bistable ferroelectric liquid-crystal spatial light modulators to be used for recording binary computer-generated holograms is experimentally demonstrated. The recording and reconstruction of cell- and point-oriented holograms are presented.