Focally evoked calcium waves in astrocyte cultures have been thought to propagate by gap-junctionmediated intercellular passage of chemical signal(s). In contrast to this mechanism we observed isolated astrocytes, which had no physical contact with other astrocytes in the culture, participating in a calcium wave. This observation requires an extracellular route of astrocyte signaling. To directly test for extracellular signaling we made cell-free lanes 10-300 m wide in conf luent cultures by deleting astrocytes with a glass pipette. After 4-8 hr of recovery, regions of conf luent astrocytes separated by lanes devoid of cells were easily located. Electrical stimulation was used to initiate calcium waves. Waves crossed narrow (<120 m) cell-free lanes in 15 of 36 cases, but failed to cross lanes wider than 120 m in eight of eight cases. The probability of crossing narrow lanes was not correlated with the distance from the stimulation site, suggesting that cells along the path of the calcium wave release the extracellular messenger(s). Calculated velocity across the acellular lanes was not significantly different from velocity through regions of conf luent astrocytes. Focal superfusion altered both the extent and the direction of calcium waves in conf luent regions. These data indicate that extracellular signals may play a role in astrocyte-astrocyte communication in situ.

Technical variant techniques expand the pediatric donor pool and reduce time from listing to transplant, but they are associated with increased morbidity and mortality.

Three cases of jaundice after ingestion of 3,4-methylenedioxymetamphetamine (MDMA), known as 'ecstasy', are reported and the complications associated with the misuse of this drug, which was initially misrepresented as 'safer than alcohol' are described. Ingestion of 'ecstasy' should be considered when investigating unexplained jaundice in younger patients. (Gut 1995; 36: 939-941)

No abstract