Antizyme, a spermidine-induced protein that binds and stimulates ornithine decarboxylase degradation, is now shown also to mediate the rapid feedback inhibition of polyamine uptake into mammalian cells. Using a cell line (HZ7) transfected with truncated antizyme cDNA, and mutant ornithine decarboxylase cell lines, we demonstrate that this newly discovered action of antizyme is distinct from its...

Cultured fibroblasts from a patient with gyrate atrophy of the retina do not convert L-ornithine, uniformly labeled with carbon-14, to proline. This metabolic block is caused by deficient L-ornithine:2-oxoacid aminotransferase activity in the patient. Her heterozygote father has intermediate activity of this enzyme.

An adult male, domestic short-haired cat with generalized retinal atrophy was found to have a 60-fold increase in plasma ornithine and ornithinuria. Ornithine-8-aminotransferase activity was undetectable in its tissues and in its cultured skin fibroblasts. This feline condition is thus analogous to gyrate atrophy of the choroid and retina in humans.

Late onset ornithine transcarbamylase deficiency (McKusick 311250) is reported in four Finnish patients, two boys and two heterozygous girls. The subtle onset and course of ornithine transcarbamylase deficiency emphasises the need for plasma ammonia and amino acid measurements in clinical situations suggesting a disorder of this nature.

Polyamines (putrescine, spermidine, and spermine) are essential for placental growth and angiogenesis. However, little is known about polyamine synthesis in the porcine placenta during conceptus development. The present study was conducted to test the hypothesis that arginine and proline are the major sources of ornithine for placental polyamine production in pigs. Placentae, amniotic fluid, an...

The prostate is a male accessory sex gland that produces secretions in seminal fluid to facilitate fertilization. Prostate secretory function is dependent on androgens, although the mechanism by which androgens exert their effects is still unclear. Polyamines are small cationic molecules that play pivotal roles in DNA transcription, translation and gene regulation. The rate-limiting enzyme in p...

In humans, plasma amino acid concentrations of branched-chain amino acids (BCAA) and aromatic amino acids (AAA) increase in states of obesity, insulin resistance and diabetes. We here assessed whether these putative biomarkers can also be identified in two different obesity and diabetic mouse models. C57BL/6 mice with diet-induced obesity (DIO) mimic the metabolic impairments of obesity in huma...

A release of (14)CO(2) not related to ornithine decarboxylase activity was found in crude leaf extracts from Lycopersicon esculentum, Avena sativa, and especially from the pyrrolizidine alkaloid-bearing Heliotropium angiospermum when incubated with [1-(14)C]- or [U-(14)C]ornithine. The total (14)CO(2) produced was about 5- to 100-fold higher than that due to ornithine decarboxylase activities c...

Changes in the contents of polyamines (PAs) in tobacco leaves (Nicotiana tabacum L. cv. Wisconsin 38) grown under 16 h photoperiod were correlated with arginine and ornithine decarboxylase (EC 4.1.1.19 and EC 4.1.1.17) and diamine oxidase (EC 1.4.3.6) activities. The maximum of free and soluble conjugated forms of PAs occurred 1-2 h after the middle of the light period and was followed by two d...

As part of our studies on the regulation of polyamine biosynthesis in Saccharomyces cerevisiae, we have investigated the effect of spermidine on the degradation of ornithine decarboxylase in this organism. We have found that in S. cerevisiae, as in other eukaryotic cells, the rate of degradation of ornithine decarboxylase, measured either enzymatically or immunologically, is increased by the ad...