Dicoumarol toxicity in cattle associated with ingestion of silage containing sweet vernal grass (Anthoxanthum odoratum)

Skullcapflavone II, a novel NQO1 inhibitor, alleviates aristolochic acid I-induced liver and kidney injury in mice

Aristolochic acid I (AAI) is a well established nephrotoxin and human carcinogen. Cytosolic NAD(P)H quinone oxidoreductase 1 (NQO1) plays an important role in the nitro reduction of aristolochic acids, leading to production of aristoloactam and AA-DNA adduct. Application of a potent NQO1 inhibitor dicoumarol is limited by its life-threatening side effect as an anticoagulant and the subsequent hemorrhagic complications. As traditional medicines containing AAI remain available in the market, novel NQO1 inhibitors are urgently needed to attenuate the toxicity of AAI exposure. In this study, we employed comprehensive 2D NQO1 biochromatography to screen candidate compounds that could bind with NQO1 protein. Four compounds, i.e., skullcapflavone II (SFII), oroxylin A, wogonin and tectochrysin were screened out from Scutellaria baicalensis. Among them, SFII was the most promising NQO1 inhibitor with a binding affinity (K_D = 4.198 μmol/L) and inhibitory activity (IC₅₀ = 2.87 μmol/L). In human normal liver cell line (L02) and human renal proximal tubular epithelial cell line (HK-2), SFII significantly alleviated AAI-induced DNA damage and apoptosis. In adult mice, oral administration of SFII dose-dependently ameliorated AAI-induced renal fibrosis and dysfunction. In infant mice, oral administration of SFII suppressed AAI-induced hepatocellular carcinoma initiation. Moreover, administration of SFII did not affect the coagulation function in short term in adult mice. In conclusion, SFII has been identified as a novel NQO1 inhibitor that might impede the risk of AAI to kidney and liver without obvious side effect.

Acute hemorrhage and death in calves following chlorophacinone exposure

Three calves were submitted to the Iowa State University Veterinary Diagnostic Laboratory for diagnostic evaluation following an abrupt increase in morbidity and mortality in a calf herd associated with epistaxis and widespread hemorrhage. Each of the submitted calves had moderate-to-severe hemorrhage within various tissues and body cavities, including the thymus, subcutaneous region of the neck, mediastinum, lungs, pericardial sac, heart, spleen, perirenal fat, urinary bladder, and skeletal muscle, including the diaphragm. An anticoagulant rodenticide screen was performed on the livers of each calf. Significant concentrations of chlorophacinone were detected at 4.2, 3.6, and 2.9 ppm in liver. Multiple piles and an open pail of white powdery material were present within the facility in which the calves were housed and were identified as the sources of chlorophacinone. Acute hemorrhage and death occurred in fourteen 1.5-mo-old, crossbred calves following ingestion of the vitamin K antagonist chlorophacinone.

A 100-Year Review: Metabolic modifiers in dairy cattle nutrition

The first issue of the Journal of Dairy Science in 1917 opened with the text of the speech by Raymond A. Pearson, president of the Iowa State College of Agriculture, at the dedication of the new dairy building at the University of Nebraska (J. Dairy Sci. 1:4-18, 1917). Fittingly, this was the birth of a new research facility and more importantly, the beginning of a new journal devoted to the sciences of milk production and manufacture of products from milk. Metabolic modifiers of dairy cow metabolism enhance, change, or interfere with normal metabolic processes in the ruminant digestive tract or alter postabsorption partitioning of nutrients among body tissues. Papers on metabolic modifiers became more frequent in the journal around 1950. Dairy farming changed radically between 1955 and 1965. Changes in housing and feeding moved more cows outside, and cows and heifers in all stages of lactation, including the dry period, were fed as a single group. Rations became wetter with the shift to corn silage as the major forage in many rations. Liberal grain feeding met the requirements of high-producing cows and increased production per cow but introduced new challenges; for example, managing and feeding cows as a group. These changes led to the introduction of new strategies that identified and expanded the use of metabolic modifiers. Research was directed at characterizing the new problems for the dairy cow created by group feeding. Metabolic modifiers went beyond feeding the cow and included environmental and housing factors and additives to reduce the incidence and severity of many new conditions and pathologies. New collaborations began among dairy cattle specialties that broadened our understanding of the workings of the cow. The Journal of Dairy Science then and now plays an enormously important role in dissemination of the findings of dairy scientists worldwide that address existing and new technologies.

Grasslands: A Source of Secondary Metabolites for Livestock Health

The need for environmentally friendly practices in animal husbandry, in conjunction with the reduction of the use of synthetic chemicals, leads us to reconsider our agricultural production systems. In that context, grassland secondary metabolites (GSMs) could offer an alternative way to support to livestock health. In fact, grasslands, especially those with high dicotyledonous plant species, present a large, pharmacologically active reservoir of secondary metabolites (e.g., phenolic compounds, alkaloids, saponins, terpenoids, carotenoids, and quinones). These molecules have activities that could improve or deteriorate health and production. This Review presents the main families of GSMs and uses examples to describe their known impact on animal health in husbandry. Techniques involved for their study are also described. A particular focus is put on anti-oxidant activities of GSMs. In fact, numerous husbandry pathologies, such as inflammation, are linked to oxidative stress and can be managed by a diet rich in anti-oxidants. The different approaches and techniques used to evaluate grassland quality for livestock health highlight the lack of efficient and reliable technics to study the activities of this complex phytococktail. Better knowledge and management of this animal health resource constitute a new multidisciplinary research field and a challenge to maintain and valorize grasslands.

Dicoumarol activates Ca2+-permeable cation channels triggering erythrocyte cell membrane scrambling

Dicoumarol, a widely used anticoagulant, may cause anemia, which may result from enhanced erythrocyte loss due to bleeding or due to accelerated erythrocyte death. Erythrocytes may undergo suicidal death or eryptosis, characterized by cell shrinkage and phospholipid scrambling of the cell membrane. Eryptosis may be triggered by increase of cytosolic Ca(2+)-activity ([Ca(2+)](i)). The present study explored, whether dicoumarol induces eryptosis. [Ca(2+)](i) was estimated from Fluo3-fluorescence, cation channel activity utilizing whole cell patch clamp, cell volume from forward scatter, phospholipid scrambling from annexin-V-binding, and hemolysis from haemoglobin release. Exposure of erythrocytes for 48 hours to dicoumarol (=10 μM) significantly increased [Ca(2+)](i), enhanced cation channel activity, decreased forward scatter, triggered annexin-V-binding and elicited hemolysis. Following exposure to 30 μM dicoumarol, annexin-V-binding affected approximately 15%, and hemolysis 2% of treated erythrocytes. The stimulation of annexin-V-binding by dicoumarol was abrogated in the nominal absence of Ca(2+). In conclusion, dicoumarol stimulates suicidal death of erythrocytes by stimulating Ca(2+) entry and subsequent triggering of Ca(2+) dependent cell membrane scrambling.

Dicoumarol toxicity in neonatal calves associated with the feeding of sweet vernal (Anthoxanthum odoratum) hay

Neonatal calves from a seasonal dairy herd in North Western Tasmania were presented for veterinary care due to mortalities and bleeding from multiple orifices. Necropsy examination revealed free blood throughout the parenchymatous organs, body cavities and connective tissues. There was no history of anticoagulant exposure, however, high quantities of dicoumarol were found in samples from hay fed to recently calved cows. No Australian cases of dicoumarol toxicity in neonatal calves have been previously documented, and dicoumarol toxicity in adult cattle would appear to be less common than in colder farming regions of the Northern Hemisphere.