Benjamin Weiss

Electrical stimulation of the superior cervical ganglia causes a rapid increase in the concentration of cyclic AMP in the pineal gland of rats. This effect is dependent upon the frequency, voltage, and duration of the stimulus and is markedly potentiated by pretreating the animals with desmethylimipramine. The increase in cyclic AMP is blocked by prior treatment of the rats with reserpine, bretylium, or propanolol but not with phentolamine. These results provide direct evidence that electrical stimulation of sympathetic nerves increases cyclic AMP in a target organ through the release of norepinephrine from presynaptic terminals acting on postsynaptic beta-adrenergic receptors.

Abstract Adenylate cyclase and phosphodiesterase activity were determined in pure cultures of astrocytes derived from newborn hamster brains. The activities of both enzymes were of the same order of magnitude as that found in whole cerebrum of newborn hamsters. Phosphodiesterase activity of SV 40 virus-transformed newborn hamster astrocytes was similar to that of normal newborn hamster astrocytes. Adenylate cyclase activity of the virally transformed cells was less than one-half that of the normal astrocytes. The results show that normal and neoplastic astrocytes contain the enzymatic machinery required to synthesize and hydrolyze adenosine 3′, 5′-monophosphate (cyclic 3′,5′-AMP). The findings suggest a role for cyclic 3′,5′-AMP in astrocyte function and indicate a possible mechanism for communication of neurons with astrocytes.

During the sixteenth to nineteenth centuries, millions of black men, women and children were captured in their ancestral homelands, often deep in the interior of sub-Saharan Africa, forcibly marched to West-African coastal embarkation points, chained inside the hold of a cargo ship, transported thousands of miles away to a foreign land where they did not even know the language, and then, frequently separated from their families, were sold like cattle and kept enslaved for the remainder of their lives. What follows is a brief account of this period, using historical and commemorative medals to illustrate this sordid epoch.