Mechanisms of generalized absence epilepsy.

Absence seizures represent bilaterally synchronous burst-firing of an ensemble of reciprocally connected neuronal populations located in the thalamus and neocortex. Recent studies demonstrate that neurons in the reticular thalamic nucleus (nRt), thalamic relay neurons (RNs), and neocortical pyramidal cells comprise a circuit that sustains the thalamocortical oscillatory burst-firing of absence seizures. Recent studies have focused on three intrinsic neuronal mechanisms that increase the likelihood of thalamocortical oscillations. The first mechanism involves T-currents elicited by activating the T-type calcium channel, which appear to trigger sustained burst-firing of thalamic neurons during absence seizures. A second intrinsic mechanism is GABA B receptors which can elicit longstanding hyperpolarization in thalamic neurons required to 'prime' T-channels for sustained burst-firing. A third mechanism involves the ability of GABA A receptors, located on nRt neurons, to mediate recurrent inhibition. Enhanced activation of GABA A receptors on nRt neurons decreases the pacemaking capacity of these cells, therefore decreasing the likelihood of generating absence seizures. Cholinergic mechanisms through modulating cortical excitability and excitatory amino acid mediated mechanisms through depolarizing thalamic neurons also play a role in absence seizures.

[Two dimensional imaging and functional evaluation of trace elements on tissues and organs by x-ray spectroscopy].

Trace elemental composition in tissues and organs was investigated to clarify the two dimensional imaging and functional evaluation using x-ray spectroscopy such as non-destruction x-ray analytical microscope (x-ray guide tube 100 microns). Al, Si, P, S, Cl, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, and Br tissues and organs, i.e., bromoderma exfolistiv squama, olfactory epithelium and anthracosis specimens were detected in microscopic area (about 10-25 mm) of the specimens and a fluorescent x-ray analysis of elemental imaging and mapping at the same time. The specimens can be observed in atmospheric pressure. The non-destruction x-ray analytical microscopic technique of trace element in biological tissues and organs was carried out on functional evaluation of trace elements, and it is shown that the technique is a useful analytical technique, which enables the detection of many trace elements simultaneously and provides image, mapping information on the diagnostic analysis of many diseases affecting the joints.

Defense mechanism of the cochlear aqueduct against infection. A morphological study in the guinea pig.

Guinea pigs were used in this study. Physiological saline, india ink, and Staphylococcus aureus were injected into the cisterna magna, and S. aureus was also injected into the scala tympani. Changes in the microstructure of the cochlear aqueduct were observed by light microscopy and also by scanning electron microscopy, mainly by means of fracture preparations. From these experimental results, it could be confirmed that the periotic duct tissue of the cochlear aqueduct reacted especially to bacterial infection.

A scanning electron microscopic study of the guinea pig cochlear aqueduct. With emphasis on fracture preparation.

The cochlear aqueduct is the duct that connects the perilymphatic space of the scala tympani with the subarachnoid space. However, its functions are not yet fully elucidated. In the present study on the cochlear aqueduct of the guinea pig, a fracture preparation method was used to obtain new findings by scanning electron microscopy.