Influence of extracellular calcium in the effects of dibekacin and diltiazem on indirectly elicited tetanic responses in the rat phrenic-hemidiaphragm preparation

1. Dibekacin (70 microM-3 mM) produced a decrease of peak tetanic tension in a concentration-dependent manner and this effect was dependent on extracellular calcium (0.3-2.5 mM Ca2+). Only minimal fade was observed and it was not related with extracellular calcium concentrations. 2. Diltiazem (30-300 microM) decreased peak tetanic tension and produced tetanic fade. Both effects were independent of extracellular calcium, although a significant potentiation was observed at 0.3 mM calcium. 3. It is concluded that tetanic parameters are related differently to extracellular calcium.     

Synthesis and anticonvulsant properties of some arylsuccinate methylpyridylimides

In reaction of alpha-phenyl, alpha-p-chlorophenyl and alpha-m-chlorophenylsuccinic acid with various aminopyridines, N-pyridyl-substituted succinimides (compounds 1-14) were obtained. These compounds were investigated for their CNS activity. Compounds 1, 2, 5, 6 and 7 displayed anticonvulsant properties in the maximum electroshock test. Compounds 5 and 6 were also active in the pentetrazole test.     

Pathogenesis and changes in the aetiology of arterio-venous fistulae

There has been a marked shift in the causes of arterio-venous fistulae. Gunshot and stab wounds used to be the most frequent cause but iatrogenic fistulae, especially those arising as a result of reconstructive skeletal operations or following diagnostic and therapeutic procedures, are now becoming increasingly common. If morphological vascular changes have not yet occurred and cardiac volume overloading has not led to permanent damage, a recently established arterio-venous fistula can be easily corrected by resection and oversewing of the artery and vein. The special cases of arterio-venous fistulae arising as a result of catheter procedures in the groin have to be identified in terms of cause and morphology in order to facilitate early surgical correction.     

Ultrastructural study of a retinoma by intraocular fine-needle aspiration biopsy

The authors present the results of a transmission electron-microscopic study performed on a tissue sample obtained by an intraocular fine-needle aspiration biopsy in a case of retinoma. The ultrastructural study showed that the tumor was composed mainly of granular osmiophilic material which contained some tumor cells. These cells showed peculiar ultrastructural characteristics, which demonstrated their neural character, and appeared in different degenerative stages. Apparently, this is the first case in whom ultrastructural technique have been applied to study an intraocular tumor sample obtained by intraocular fine-needle aspiration biopsy, and the first case of retinoma studied by such a diagnostic approach.     

Regulation of G-PROTEIN mRNA abundancy and cAMP accumulation after long-term opioid incubation in primary cultures of astroglia from the rat cerebral cortex.

Primary astroglial cultures were incubated with delta (10(-6) M DPDPE) or kappa (10(-5) M U-50,488H) receptor agonists for 5 days. Thereafter, the acute inhibitory actions of delta or kappa receptor agonists on forskolin stimulated cAMP accumulation were assayed. The G alpha s, G alpha i-1 and G alpha i-2 mRNA levels were quantified after 5 days of either delta or kappa receptor agonist treatment using a solution hybridization, RNase protection assay. Pronounced effects were observed after 5 days of kappa receptor agonist [10(-5) M U-50,488H] incubation. This treatment resulted in an attenuation in the acute inhibitory action of delta and kappa receptor agonists. Furthermore, a decreased stimulatory action of forskolin was seen. Similar effects were also seen after delta receptor stimulation. We also investigated the effects after 24 h and 3 days of incubation with the kappa receptor agonist (10(-5) M) U-50,488H. The 24 h incubation resulted in a decreased sensitivity to the acute inhibitory action of delta and kappa receptor agonists in the astroglial cultures. This effect was further accentuated after the 3 days of incubation with 10(-5) M U-50,488H. No significant change was seen in the basal accumulation of cAMP after incubation with the kappa agonist U-50,488H. However, after 5 days of incubation with the delta agonist DPDPE, a significantly increased basal accumulation of cAMP was seen in the astroglial cultures. After 5 days of delta or kappa agonist incubation, an increase in G alpha s mRNA level and a decrease in G alpha i-2 mRNA level was seen compared with controls. No statistically significant alterations in the amount of G alpha i-1 mRNA were seen. The data obtained in the present study indicate that the effects of long-term opioid treatment alters the sensitivity of glial cell opioid receptors. Furthermore, long term opioid treatment induces alterations in glial G-protein mRNA levels.