Some pharmacokinetic data about furaltadone and nitrofurazone administered orally to preruminant calves

Phenotypic assays in yeast and zebrafish reveal drugs that rescue ATP13A2 deficiency

Mutations in ATP13A2 (PARK9) are causally linked to the rare neurodegenerative disorders Kufor-Rakeb syndrome, hereditary spastic paraplegia and neuronal ceroid lipofuscinosis. This suggests that ATP13A2, a lysosomal cation-transporting ATPase, plays a crucial role in neuronal cells. The heterogeneity of the clinical spectrum of ATP13A2-associated disorders is not yet well understood and currently, these diseases remain without effective treatment. Interestingly, ATP13A2 is widely conserved among eukaryotes, and the yeast model for ATP13A2 deficiency was the first to indicate a role in heavy metal homeostasis, which was later confirmed in human cells. In this study, we show that the deletion of YPK9 (the yeast orthologue of ATP13A2) in Saccharomyces cerevisiae leads to growth impairment in the presence of Zn2+, Mn2+, Co2+ and Ni2+, with the strongest phenotype being observed in the presence of zinc. Using the ypk9Δ mutant, we developed a high-throughput growth rescue screen based on the Zn2+ sensitivity phenotype. Screening of two libraries of Food and Drug Administration-approved drugs identified 11 compounds that rescued growth. Subsequently, we generated a zebrafish model for ATP13A2 deficiency and found that both partial and complete loss of atp13a2 function led to increased sensitivity to Mn2+. Based on this phenotype, we confirmed two of the drugs found in the yeast screen to also exert a rescue effect in zebrafish-N-acetylcysteine, a potent antioxidant, and furaltadone, a nitrofuran antibiotic. This study further supports that combining the high-throughput screening capacity of yeast with rapid in vivo drug testing in zebrafish can represent an efficient drug repurposing strategy in the context of rare inherited disorders involving conserved genes. This work also deepens the understanding of the role of ATP13A2 in heavy metal detoxification and provides a new in vivo model for investigating ATP13A2 deficiency.

Depletion of four nitrofuran antibiotics and their tissue-bound metabolites in porcine tissues and determination using LC-MS/MS and HPLC-UV

Depletion of the nitrofuran antibiotics furazolidone, furaltadone, nitrofurantoin and nitrofurazone and their tissue-bound metabolites AOZ, AMOZ, AHD and SEM from pig muscle, liver and kidney tissues is described. Groups of pigs were given feed medicated with one of the nitrofuran drugs at a therapeutic concentration (400?mg?kg(-1)) for ten days. Animals were slaughtered at intervals and tissue samples collected for analysis for six weeks following withdrawal of medicated feed. These samples were analysed both for parent nitrofurans (using LC-MS/MS and HPLC-UV), and for tissue-bound metabolites (using LC-MS/MS). The parent drugs were detectable only sporadically and only in pigs subjected to no withdrawal period whatsoever. This confirms the instability of the four major nitrofuran antibiotics in edible tissues. In contrast, the metabolites accumulated to high concentrations in tissues (ppm levels) and had depletion half lives of between 5.5 and 15.5 days. The metabolites of all four drugs were still readily detectable in tissues six weeks after cessation of treatment. This emphasizes the benefits of monitoring for the stable metabolites of the nitrofurans.

Effects of feed additives and veterinary drugs on aldosterone production and release by porcine adrenal cells in vitro

The preparation of suspensions of porcine adrenocortical cells is described. Within the conditions adopted, the cell suspension responded to various agents as expected. It was possible to screen drugs (standard range 0.3-100 microM, incubation period 1 h) for actions on the production/release of aldosterone by the cortical cells using 1 microM deoxycorticosterone as substrate. Progesterone, pregnenolone or corticosterone were also used as substrates. Feed additives of the quinoxaline type induced a slowly developing inhibition of aldosterone production/release by the cell suspension, which was virtually irreversible. During the standard 1 h incubation period inhibitions of up to 22 +/- 2% of control were observed, which increased upon prolongation of the incubation by 2 h. With 100 microM cyadox the inhibition increased from 19 +/- 2% to 35 +/- 2% with prolonged incubation. Ten nitrofuran compounds exerted a more rapidly developing inhibition (by up to 79 +/- 1% of control) of aldosterone production/release, which was reversible. A submaximal inhibition with 10 microM furazolidone of 21 +/- 5% increased to 40 +/- 1% with longer incubation. The concentrations at which these compounds exerted this effect in vitro were well below the peak blood plasma concentrations encountered after administration of the drugs in therapeutic doses. Polyether-antibacterials/ionophores rapidly inhibited aldosterone production/release (to 26 +/- 1% of control) and this effect was completely reversible. The nitroimidazole compounds tested did not affect aldosterone production/release when deoxycorticosterone or progesterone were used as substrates. With use of corticosterone and to a lesser extent with pregnenolone as substrates a clear inhibition (to 73 +/- 3% of control) of aldosterone production was obtained. Amprolium in concentrations up to 100 microM, with deoxycorticosterone as substrate, did not induce a significant change in aldosterone production/release by the suspension of adrenocortical cells. In the same dose range tylosin and roxarsone induced a small but significant inhibition (by up to 10 +/- 3% of control) of aldosterone production/release, which was not dose-dependent. It is concluded that a wide range of growth-promoting drugs may be able to change aldosterone production/release in the animal.

Postmortal degradation of furazolidone and furaltadone in edible tissues of calves

Rapid and complete postmortal degradation of furazolidone and furaltadone occurred in liver, kidney and muscle tissues of veal calves. Different degradation half-lives were observed between these tissues, the mean ranging from less than 7 minutes to 63 minutes. At 24 h after slaughter the parent nitrofurans were no longer detectable in edible tissues. For residue monitoring purposes plasma and/or urine can be used, if these matrices are treated in a specific way immediately after slaughter; muscle tissues and organs are unsuitable for residue monitoring of parent nitrofurans.