The effect of amygdala kindling on hippocampal neurogenesis coincides with decreased reelin and DISC1 expression in the adult dentate gyrus.

Temporal lobe seizures can induce the proliferation and abnormal migration of newly generated dentate granule cells, but little is known about the molecular mechanisms that govern these pathological events. Reelin and DISC1 (disrupted-in-schizophrenia 1) are proteins that play a regulatory role in the maturation and integration of new neurons in the developing and adult brain. In this study, we examined whether amygdala kindling results in aberrant neurogenesis and altered expression of reelin and DISC1 in the adult dentate gyrus. Using doublecortin immunohistochemistry, we found that short-term kindling (i.e., 30 electrical stimulations) significantly increased the number of immature neurons in the dentate subgranular zone (SGZ), whereas long-term kindling (i.e., 99 electrical stimulations) did not. However, doublecortin-labeled neurons in long-term kindled rats showed greater dendritic complexity than they did in short-term kindled or control rats. We also found that long-term kindling decreased the number of reelin-positive cells and decreased DISC1 expression in the dentate granule cell layer and subgranular zone. Interestingly, kindling-induced changes in reelin and DISC1 expression coincided with the appearance of ectopically located Prox1-labeled granule cells in the hilus. These effects occurred independently of alterations in granule cell layer length, dentate volume, or the number of hilar neurons. Taken together, these findings suggest a novel role for DISC1 in the pathophysiology of temporal lobe epilepsy and further suggest that changes in reelin and DISC1 expression may contribute to aberrant neurogenesis in the kindling model.

Determination of poultry feed-through insecticide activity in an in vivo anticoccidial assay.

The ability of an in vivo anticoccidial assay to identify potential feed-through insecticides was demonstrated using first-instar Lucilia sericata on droppings from chicks fed medicated diets. Cyromazine, a commercially available feed-through insect growth regulator, ivermectin, diflubenzuron, fipronil, permethrin, and 2 experimental compounds were effective in varying degrees in killing L. sericata larvae. Eleven coccidiostats were effective against the protozoan parasites (Eimeria spp.) at commercially used levels, whereas they were ineffective against Lucilia larvae.

Is two-photon absorption a limitation to dark soliton switching?

It is shown that two-photon absorption does not always place a fundamental limitation on soliton devices: The steering angle, the key characteristic of switching devices based on the propagation of dark spatial solitons, is almost preserved as the intensity of the background wave decays in the presence of weak two-photon absorption.

Observation of fundamental dark spatial solitons in semiconductors using picosecond pulses.

We report what is to our knowledge the first observation of fundamental dark spatial solitons. The solitons are launched in bulk semiconductors using an initial condition with odd symmetry. In order to form the initial condition, a glass platelet is positioned in one half of an incident 30-psec pulse, creating a pi phase shift in the spatial profile. Several propagation parameters for the solitons are measured experimentally, and good agreement with theory is obtained.

Direct measurement of the transverse velocity of dark spatial solitons.

We describe the direct experimental measurement of the transverse propagation velocities of dark spatial solitons. Good agreement is obtained from a comparison of the velocities measured experimentally and the velocities predicted by the two-dimensional theory of Zakharov and Shabat [Sov. Phys. JETP 37, 823 (1973)].

Use of digital filtering techniques in the spatial profiling of pulsed laser beams.

A method of spatially profiling pulsed laser beams using a digital filtering technique is described. This technique has the advantage of requiring fewer experimental scans of the laser beam to produce usable lownoise replicas of the laser beam's spatial profile than previously described methods. The technique is simple and can be implemented on a small laboratory computer.

Reversible optical computing circuits.

Planar optical implementations of binary adders are developed using a three-port nonlinear interface device as the single computing primitive. The device is bit-conserving and both optically and logically reversible.