G. H. Zeman

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A new method of exposing tissues to X rays in a lead Faraday cage has made it possible to examine directly radiation damage to isolated neuronal tissue. Thin slices of hippocampus from brains of euthanized guinea pigs were exposed to 17.4 ke V X radiation. Electrophysiological recordings were made before, during, and after exposure to doses between 5 and 65(More)
Acute lethality syndromes produced by the accidental exposure of humans to mixed neutron and gamma radiation from external sources can be related to acute lethality from photon irradiation using the relative biological effectiveness (RBE) for common end points. We used the canine as a model to study injury following exposure to mixed neutron and gamma(More)
By sensitive enzymatic micromethods several putative neurotransmitters were measured in four identifiable neurons of Aplysia californica (R-2, R-14, L-11, and C-1). Serotonin was found in all of these neurons, and octopamine in all but C-1. Acetylcholine has been previously reported to be present in R-2 and L-11. The catecholamines, norepinephrine and(More)
Exponential and density-inhibited cultures of C3H/10T1/2 cells were exposed to a single dose of 0.3 Gy of fission neutrons delivered at rates ranging from 0.005 to 0.1 Gy/min. No discernible effect upon cell survival or transformation was observed by a lowering of the fission neutron dose rate in either exponential or plateau cultures. At the level of 2.3 x(More)
To investigate the effects of nonuniform irradiation on the small intestine, we prepared 24 dogs for continent isoperistaltic ileostomies under aseptic surgical conditions and general anesthesia. After a 3-week recovery period, the ileum was catheterized with a fiberoptic endoscope to observe the intestinal mucosa and to harvest mucosal biopsies. The(More)
A 50 kVp molybdenum target/filter x-ray tube has been installed inside a lead-shielded Faraday cage. High-dose rates of up to 1.54 Gy min-1 (17.4 keV weighted average photons) have been used to conduct local in vitro irradiations of the hippocampal region of guinea pig brains. Electrophysiological recordings of subtle changes in neuronal activity indicate(More)