The effect of redox-related species of nitrogen monoxide on transferrin and iron uptake and cellular proliferation of erythroleukemia (K562) cells.

The iron-responsive element-binding protein (IRE-BP) modulates both ferritin mRNA translation and transferrin receptor (TfR) mRNA stability by binding to specific mRNA sequences called iron-responsive elements (IREs). The regulation of IRE-BP in situ could possibly occur either through its Fe-S cluster and/or via free cysteine sulphydryl groups such as cysteine 437 (Philpott et al, J Biol Chem 268:17655, 1993; and Hirling et al, EMBO J 13:453, 1994). Recently, nitrogen monoxide (NO) has been shown to have markedly different biologic effects depending on its redox state (Lipton et al, Nature 364:626, 1993).

Growth of human tumor cell lines in transferrin-free, low-iron medium.

Iron is essential for tumor cell growth. Previous studies have demonstrated that apart from transferrin-bound iron uptake, mammalian cells also possess a transport system capable of efficiently obtaining iron from small molecular weight iron chelates (Sturrock et al., 1990).

Nitrogen monoxide decreases iron uptake from transferrin but does not mobilise iron from prelabelled neoplastic cells.

The effect of congeners of nitrogen monoxide (NO) on iron (Fe) uptake from 59Fe-125I-transferrin (Tf) and release of 59Fe from prelabelled cells have been investigated in SK-MEL-28 human melanoma cells, human K562 cells and mouse MDW-4 cells. These studies have been initiated as it has been suggested that the tumoricidal effects of NO may be mediated by its acting to release Fe from cells (Hibbs et al., 1984 Biochem.

Production of transferrin by human cell lines in a defined protein-free system: detection by ELISA.

A double sandwich enzyme immunoassay using a combination of two polyclonal and one monoclonal antibodies was developed to quantitate transferrin in various human cell lines (U 937, K 562, Jiyoye, Jurkat, Raji, THP-1, HeLa) and transferrin secreted by these cells cultured in a defined protein-free medium. In the developed assay the measurable range in our experimental system is 1 to 25 ng/mL of human transferrin and the interassay coefficient of variation ranged from 11.3 to 16.

[Microscopic fungi in chicken feed mixtures, their toxigenicity and toxicity for the chick embryo].

Contamination with microscopic fungi was studied in broiler complete feed mixtures in 1983-1984. The contamination levels ranged from 10(1) to 10(5) of fungus units per gram of feed (mostly around 10(3) units per gram). Sixty species of microscopic fungi of sixteen genera were isolated from the feeds.