Localization of cyclic adenosine monophosphate in the teleost retina: effects of dopamine and prolonged darkness

Localization of cyclic adenosine monophosphate (cAMP) in the white perch retina was carried out with immunohistochemical and autoradiographic methods. Following exposure to dopamine or prolonged darkness, cAMP staining was observed by immunohistochemistry in the distal part of the inner nuclear layer, i.e. in the horizontal cells. After exposure to dopamine, increased levels of cAMP were also observed by autoradiography in many horizontal cells. Finally, increased levels of cAMP staining were observed immunohistochemically following incubation with dopamine in all types of cone-related horizontal cells that had been isolated and maintained in culture.     

Effects of d-aspartate on excitatory amino acid-induced release of [H]GABA from goldfish retina

The rate of release of [³H]GABA from isolated intact goldfish retinas was studied. Release of [³H]GABA is markedly stimulated by the inclusion in the incubation medium of the photoreceptor neurotransmitter candidates l-glutamate (l-Glu) and l-aspartate (l-Asp), and the glutamate analogs, kainate and quisqualate. At micromolar concentrations, kainate and quisqualate are effective releasers of [³H]GABA, whereas millimolar concentrations of l-Glu and l-Asp are required to release comparable amounts of [³H]GABA. The d-isomers of aspartate (d-Asp) and glutamate (d-Glu) are able to release [³H]GABA, but only when applied at high concentrations (3–30 mM). In the presence of 5 mM d-Asp, the effect of l-Glu in releasing [³H]GABA was markedly potentiated. This dose-response curve of l-Glu was shifted to the left in the presence of d-Asp, although the maximal amount of release was unchanged. d-Asp at 5 mM only slightly increased the GABA release induced by quisqualate, and it did not increase the GABA release induced by kainate. Finally, low concentrations of l-Asp were potentiated by d-Asp, but higher concentrations of l-Asp (3–10 mM) were clearly inhibited by this agent. This biphasic effect of d-Asp on l-Asp-induced release of [³H]GABA is a possible explanation for previously conflicting reports of d-Asp's effect on l-Asp action^2,8,29. Our data suggest that d-Asp has both pre- and postsynaptic sites of action.     

An incomplete cold-reactive gamma G antibody with i specificity in infectious mononucleosis

Summary. A new cold reactive antibody directed against fetal (i) cells is described in 90% of patients with infectious mononucleosis. It appears to be the 7S counterpart of the previously described 19S anti-i antibody. The 7S anti-i antibody interacts with a 19S anti γ globulin and the combination is responsible for the majority of the cold agglutinin phenomena previously shown in this disorder. The highest titers were detected in patients with severe hemolytic anemia, leukopenia, thrombocytopenia or combinations thereof.