Rat glial tumors, induced by injections of N-nitrosomethylurea, were plated and propagated in culture. Among a few cell strains obtained, one clone contains S-100 protein, which is unique to brain in vertebrates. Stationary-phase cultures contain approximately ten times more S-100 protein per cell than exponentially growing cells. When injected into newborn rats, cells producing S-100 grew as a glial tumor, which contained S-100 protein.

Three clonal strains of epithelial cells were established from a transplantable rat pituitary tumor. These strains have been serially propagated for 14-25 months. They were subcultured every 2-3 weeks. Cells of the original strain have increased by a factor of more than 10 40 . The generation times of the 3 lines were similar and ranged between 30 and 40 hr. Cells of all 3 strains synthesize growth hormone and secrete it into the culture medium. Growth hormone synthesized in vitro is indistinguishable from normal rat pituitary growth hormone as measured by micro-complement fixation and radioimmunoassay. The specific activity of growth hormone production was estimated to be 20-40 fig/ing cell nitrogen/24 hr for the most vigorous strain. There has been no decrease in the rate of cell division nor decline in growth hormone secretion since the cells were established in culture. (Endocrinology 82: 342, 1968)

Antibodies to bradykinin and angiotensin have been produced in rabbits by the use of conjugates containing albumin and the hapten, covalently bound. The use of water-soluble carbodiimide reagents provided an easy and rapid method of synthesis of the antigenic conjugates.

6-Sulfidopeptide-containing leukotriene-like immunoreactivity was synthesized in gerbil forebrains after bilateral common carotid occlusion and reperfusion. At 5, 10, or 15 minutes of ischemia, concentrations increased significantly and became more marked on reperfusion. Immunoreactivity was highest in forebrain gray matter and was below the detection limit of the assay in brain regions remote from the zone of ischemia. In vitro experiments with vascular cells and organ cultures of cerebral arteries indicate that the cerebral blood vessel wall is not a major source of biosynthetic activity in the brain. These experiments demonstrate leukotriene biosynthesis by the brain. Because synthesis occurs during ischemia and reperfusion and because leukotrienes are potent vasoconstrictors and promoters of tissue edema, they may play a role in the pathophysiology of cerebral ischemia.