Unusual expression of the Hu paraneoplastic antigen in the visual system.

The Hu paraneoplastic antigen is an RNA binding protein important in the development and maintenance of neurons. Hu has homology with the product of Elav, a gene that is essential for Drosophila visual system development. Using immunohistochemical staining, the Hu antigen was identified in most retinal neurons but was not detected in the photoreceptors. Hu is, therefore, not essential for the maintenance of all differentiated neurons. Hu immunolabeling was consistently found in glia in the optic nerve. The presence of the Hu antigen in a subset of glial cells emphasizes the heterogeneity of glial phenotype and raises the possibility that these cells may retain properties of undifferentiated neural stem cells.

Basic fibroblast growth factor increases nitric oxide synthase production in bovine endothelial cells.

Basic fibroblast growth factor (bFGF) and nitric oxide (NO) are expressed by endothelial cells (EC) and are involved in regulation of endothelial functions. In vivo, bFGF has a hypotensive effect which is mediated, in part, through activation of nitric oxide synthase (NOS) and the subsequent generation of NO. Thus we hypothesized that regulation of NOS in EC might be modulated by bFGF. bFGF treatment of EC in vitro resulted in increased NADPH diaphorase staining, a histochemical marker associated with the presence of NOS. Using cGMP generation in a reporter cell as a bioassay for NO release, we demonstrated that bFGF treatment of EC leads to increased production of biologically active NO. Furthermore, bFGF treatment of EC resulted in an increase in cellular content of the endothelial form of NOS as shown by Western blot analysis. Finally, Northern blot analysis was used to demonstrate that message levels of the constitutive, calcium-dependent, endothelial form of NOS is increased in EC by treatment with bFGF in vitro. These results suggest that bFGF has potential to regulate vascular tone through the modulation of levels of endothelial NOS.

In vitro inhibition of mouse epidermal cell lipoxygenase by flavonoids: structure-activity relationships.

Lipoxygenase was extracted from mouse epidermal cells and partially purified by ammonium sulfate precipitation. Using a biological oxygen monitor for activity measurements and linoleic acid as substrate, the effect of a series of flavonoids on lipoxygenase activity was determined. Flavone itself did not inhibit lipoxygenase, but hydroxylated derivatives retaining the double bond in the 2,3 position and having a hydroxyl group in the 3 position (such as quercetin and 3-hydroxy-flavone) were potent lipoxygenase inhibitors compared to flavonoids without those particular functional groups.

Microsomal P-450 induction by some secondary products from thermal oxidation of dietary lipids: epidermal hyperplasia, mutagenicity and cytochrome P-450 activities.

Distillable secondary products from roasted fowl were found to be cytotoxic but not mutagenic when assayed with Salmonella typhimurium strains TA98, TA100 and TA1537. A crudely separated fraction of the volatiles produced focal hyperplasia and damage to the epidermis of the backs of mice. The volatiles also caused an apparent synthesis of non-constitutive forms of rat hepatic cytochromes P-450 which metabolize benzo[a]pyrene B [a]P differently from the constitutive P-450.

Cytochrome P-450 mediated interaction between hydroperoxide and molecular oxygen. A proposed method for P-450 kinetic studies.

Rat liver cytochrome P-450 mediates a novel reaction between equimolar quantities of dissolved oxygen and organic hydroperoxides. The reaction shares some of the properties of both NADPH-O2 dependent hydroxylation and NADPH-O2 independent peroxidase reactions, but does not require either NADPH, phosphatidylcholine, or any substrates other than hydroperoxide and oxygen. It proceeds at a rate approximately 100 times faster than other well known P-450 hydroxylation reactions. Monitoring the rate of O2 consumption in this novel reaction may be a simple and rapid means for studying the kinetics of cytochrome P-450.