Mobilization of Ca++ was estimated in single rabbit blood platelets with digital imaging microscopy. Concanavalin A (Con A) caused a rapid initial increase in intracellular concentration of Ca++ ...(Ca++i) with a latent time of about 20 sec, followed by a sustained increase in Ca++i. This effect of Con A was antagonized by α-methyl-D-mannose, which already was shown to antagonize the inhibitory effect of Con A on 5-HT transport, indicating that this effect of Con A was also derived from its binding to cell surface glycoproteins. The presence of EGTA in the medium did not affect the initial rise, but inhibited the latter phase of sustained rise. Thus, Con A induced elevation of Ca++i was suggested to consist of two different processes: mobilization of Ca++ from the intracellular storage sites and successive Ca++ influx through Ca++ channels. The effect of Con A on the 5-HT transport was tested in the presence of EGTA, a condition where no Ca++ influx occurs. The results indicate that Con A induced inhibition of 5-HT transport was not influenced by EGTA in the medium. It is suggested that the effect of Con A on 5-HT transport might be exerted through the Ca++ mobilization from its intracellular storage sites.
The ontogenesis of rearing and stereotypy behavior in response to apomorphine were investigated in the developing rat. The rearing was rarely observed in 15-day-old rats but distinctly in 18-day-old ...ones. A subcutaneous injection of apomorphine in dose of 1 mg/kg or 2 mg/kg decreased the frequency of rearing in older animals than day 20. On the other hand, 15-day-old rats were already responsive to apomorphine in stereotypy behavior. There was a reciprocal relationship between rearing and stereotypy responses to apomorphine in rat older than 18 days. Functional relationship between rearing and stereotypy in response to apomorphine were discussed in view of the central dopaminergic mechanisms in developing rats.
In August and September 1990, several ice depolarization events associated with summertime thunderclouds were observed at the CSK Osaka earth station using the CS-3 beacon signal (19.45 GHz, RHCP, ...EL=49.5 degrees ). The observation of the CS-3 beacon signal has revealed characteristic changes in XPD (cross-polarization discrimination) and cross-polar phase caused by high-altitude ice crystals in thunderclouds. In light of recent thunderstorm electrification theory and other thundercloud observations, these kinds of rapid changes are related to the intercloud discharge near the cloud top, which does not necessarily correspond to the lightning flashes seen on the ground. The impact of thunderstorm events upon dual-polarization satellite communication links using linear horizontal and vertical polarizations is considered.< >
The distribution of cross-polarized phase relative to copolarized phase, which is important in the design of depolarization cancelers, is presented using the CS-2 beacon signal (19.45 GHz, right-hand ...circular. EL=49.5 degrees ), and its dependence upon rainfall rates is discussed. Also, additional depolarizations due to ice effects are estimated and a calculation is made to show the possibility of cancelling them on the complex depolarization plane. The analysis of the cross-polar phase characteristics of Ka-band depolarization indicates a possibility of its compensation by phase shifters within small rainfall rates, which do not exceed a general rain margin (<5-10 dB). Consideration of the differential phase shift cancellation mechanism on the complex depolarization plane suggests that the improvement for the ice effects is approximately estimated by the additional ice depolarization observed in the cross-polar discrimination (XPD) amplitude.< >
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