Role of prostaglandins on growth hormone secretion: PGE2 a physiological stimulator.

PGE2 at 5 X 10(-8)M is a significant stimulator of GH release and seems to act at a step prior to the first signal for the inhibitory effect of SS. The amount of PGE2 released in the culture medium would appear, from what we have seen in our studies to date, to rule out any possibility that PGE2 is a GRF. However, the powerful role of PGE2 in the GH secretion process is evident.

Prostaglandin synthesis by isolated rat renal glomeruli.

The PGE2, PGF2 alpha and 6-keto-PGF1 alpha contents of the incubation medium of glomeruli isolated from rat kidney were measured at different times with or without addition of arachidonic acid. These prostaglandins accumulated progressively with time and reached equilibrium after 60--120 min incubation. Synthesis of the 3 prostaglandins was inhibited when indomethacin was added whereas it was markedly enhanced, mainly for PGE2, at increasing doses of arachidonic acid.

Purification of bacterial endotoxins by zonal centrifugation.

In this paper, we describe a cultivation procedure in large-capacity fermentors (200 liters) and the purification of the Salmonella crude extracts by means of zonal centrifugation in a sucrose gradient. Briefly, the endotoxin has been extracted from salmonellae with hypertonic solutions. The crude endotoxin was shown to contain several antigens, mainly r(1), r(2), r(3), or heterologous antigen.