Zinc transport by fibroblasts from patients with acrodermatitis enteropathica

Acrodermatitis enteropathica (AE) is a zinc deficiency disease. To date, the only defect has been demonstrated in the gut. We have investigated zinc uptake in fibroblasts established from four unrelated patients with AE using normal skin fibroblasts as controls. Zinc content of AE and control cells was similar (0.3 fmol/cell). Zinc accumulation over 24 h from a complete culture medium was similar in both normal controls and mutant cells. The fraction of zinc removed by Pronase treatment remained constant at 50 pmol/micrograms DNA, whereas the zinc remaining after Pronase treatment accumulated rapidly for 8 h, then more slowly. Analysis of binding data showed no significant difference between AE and control cells, with apparent Ka values of 4-6 X 10(6) M-1 and between 1 and 2 X 10(8) receptors/cell. Analysis of Pronase resistant data showed no difference between the control and the mutant cells with apparent Km values of 0.2-0.3 microM and Vmax values of 17-19 pmol/micrograms DNA/h. No difference in zinc efflux rates was detected. We conclude that the defect that underlies acrodermatitis enteropathica is either not expressed in fibroblasts or cannot be detected under these experimental conditions.     

Phospholipase D, tumor promoters, proliferation and prostaglandins.

Phosphatidylcholine hydrolysis by phospholipase D is a widespread response to cellular stimulation. However, the downstream signaling events subsequent to phosphatidylcholine hydrolysis are just beginning to be determined. Initially it was proposed that diglyceride formation by phospholipase D and phosphatidate phosphohydrolase resulted in long-term stimulation of protein kinase C. However, recent studies indicate that phosphatidic acid is the relevant signaling molecule in some signaling pathways. The present review will summarize studies of phospholipase D in the response of cells to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate, which causes cells to mimic the phenotype of oncogenic transformation. The role of phospholipase D in stimulation of Raf-1 and prostaglandin H synthase type-2 is emphasized.     

Metabolism of prostaglandins E, A, and C in serum.

Three prostaglandin-metabolizing enzymes were detected in human serum. One enzyme was a dehydrase that converted prostaglandin E to prostaglandin A, the second was a prostaglandin A isomerase that converted prostaglandin A to prostaglandin C and the third was a prostaglandin C isomerase that converted prostaglandin C to prostaglandin B. All three were inactivated by sulfhydryl blocking agents. In human serum, only prostaglandin C isomerase had high activity, whereas the two other enzymes had very low activity. In rabbit serum both isomerases were very active, but dehydrase activity could not be detected. Prostaglandin C isomerase activity was also found in crystallized human serum albumin and rabbit serum albumin.     

Interrelationships between prostaglandins, cyclic AMP and steroids in ovulation.

Ovulation is a complex phenomenon, involving a series of biochemical events within the ovary, leading to the rupture of the follicle. This paper summarizes recent studies in our laboratory of some of these biochemical changes using the rabbit as an experimental model. It has been shown in our laboratory that isolated Graafian follicles obtained from oestrous rabbits synthesize steroids and cyclic AMP when incubated in vitro. Luteinizing hormone added to the incubation medium increased steroidogenesis and cyclic AMP synthesis many fold. When follicles were isolated from rabbits at different times following the ovulatory stimulus (mating or HCG injection) it was found that the in vitro response to LH in terms of steroidogenesis and cylcic AMP synthesis was lost as ovulation approached. In contrast, when prostaglandins (PGF and PGE) were measured in rabbit Graafian follicles it was found that the PGF and PGE levels increased as ovulation approached. From these data and from reports in the literature, we have developed a hypothetical model for ovulation in the rabbit which may help in a better understanding of the ovulatory process.     

The role of prostaglandins in hypertension. I. The release of prostaglandins by aorta strips of renal, DOCA-salt, and spontaneously hypertensive rats

The release of prostaglandin-like (PG-like) material by aorta strips of normotensive and hypertensive rats has been studied in vitro. When incubated in an oxygenated Krebs solution kept at 37 degrees C, aorta strips removed from 8- and 12-week-old spontaneously hypertensive (SH) rats generate 1.2-2.5 times more PG-like material than aorta strips from age-matched normotensive Wistar (NW) rats. The overproduction of PG-like material by aorta strips of SH rats did not precede the development of hypertension in SH rats. Aorta strips derived from renal and DOCA-salt hypertensive rats produced 1.5-3 times more PG-like material than aorta strips from NW rats. The production of PG-like material by aorta strips of renal and DOCA-salt hypertensive rats was largely reduced when hypertension was interrupted in these animals, thus suggesting that the alteration taking place in the arteries of hypertensive rats (namely increased production of PGs) during the development of hypertension was reversible. The production of PG-like material by aorta strips of hypertensive rats was inhibited by indomethacin. Analysis of the PG-like material by bioassays and thin-layer chromatography suggests the presence of PGE2 and PGE1. The possible involvement of these PGs in the pathogenesis of hypertension in rats is discussed.     

Luteolytic prostaglandins. Synthesis and biological activity.

Analogues of PGF2 alpha with enhanced luteolytic activity were synthesized using the Corey synthesis. The luteolytic activity of the new prostaglandins was tested in the hamster. In addition the smooth muscle activity of the new compounds was compared with that of PGA2 on the longitudinal strip of rat stomach fundus. Structure-activity relationships in the new series of 17,18,19,20-tetranor-16-thienyl-oxy-PGF2 alpha are discussed.     

A simple isotope derivative assay for prostaglandins and prostaglandin metabolites. I. Assay of e-type prostaglandins.

Prostaglandins of the E series may be reduced with [³H]borohydride to their corresponding counterparts of the F series: during reduction a tritium label is incorporated into the molecule. We describe a simple assay based on this reaction which can be used to measure E-type prostaglandins, and with slight modifications, to measure F-, A-, and D-type prostaglandins, as well as the 15-keto and 13,14-dihydro-15-keto metabolites. The assay will estimate 1–10 ng PGE compounds (～10^?11–10^?12 moles) but some prior purification of the sample is necessary.