Detection of Hypoglycin A and MCPrG Metabolites in the Milk and Urine of Pasture Dairy Cows after Intake of Sycamore Seedlings

Release of Hypoglycin A from Hypoglycin B and Decrease of Hypoglycin A and Methylene Cyclopropyl Glycine Concentrations in Ruminal Fluid Batch Cultures

The transformation of hypoglycin A (HGA), hypoglycin B (HGB), and methylene cyclopropyl glycine (MCPrG) in ruminal fluid batch cultures was investigated, and the effect of these toxins on the batch culture microorganisms using microbial metabolites was measured. An experiment was conducted using ovine ruminal fluid batch cultures and the ANKOM RF Gas Production System over four runs, each with an incubation period of 48 h. The fermenters contained 200 mg of (i) a substrate mixture (80% cellulose, 20% starch; CSM), (ii) CSM and 1.5 mL of a solution of pure toxins (a mixture of 500 ng/mL HGA and MCPrG each; PCM), or (iii) CSM and 100 mg sycamore maple seeds (SMS). Each fermenter contained 30 mL of inoculum (ruminal fluid and buffer, 1:2 v/v). For control, autoclaved ruminal fluid was incubated with CSM, PCM, and SMS, respectively. Samples were taken from the liquid phase of the fermenters and analyzed using liquid chromatography-tandem mass spectrometry (LC/MS-MS) for sycamore maple toxins and metabolites. Microbial activity was assessed using gas production, short chain fatty acids, and NH3 concentration. Additionally, pH and redox potentials were measured. In PCM, HGA and MCPrG concentrations rapidly decreased (p < 0.05), and were not measurable anymore after a 24 h incubation period. In SMS, the initial concentrations were 4.7 ± 1.4 µg/mL HGA, 19.9 ± 5.41 µg/mL HGB, and 1.2 ± 0.33 µg/mL MCPrG. In SMS, HGA increased in 24 h, coincidently to a decrease in HGB concentration (p < 0.05). We modeled a rapid conversion of HGB to HGA, accompanied by progressive HGA transformation. The concentration of MCPrG was constant until 4 h and decreased afterwards (p < 0.05). In SMS incubations, HGA and MCPrG concentrations of 5.6 ± 1.5 and 0.32 ± 0.090 µg/mL remained after 48 h, respectively. The HGB to HGA conversion and transformation of HGA and MCPrG also occurred in autoclaved ruminal fluid. Gas production and microbial metabolite concentrations were higher in SMS compared to CSM and PCM (p < 0.05), as the seeds were used as an additional substrate by the batch culture microorganisms.

An ongoing concern: 20 years of research on equine atypical myopathy

Anne-Christine François, Benoît Renaud, Caroline-Julia Kruse, Christel Marcillaud-Pitel and Dominique-Marie Votion of the Atypical Myopathy Alert Group discuss insights from 20 years of research and surveillance on equine atypical myopathy.

A review on mechanistic aspects of litchi fruit induced acute encephalopathy

Litchi (Litchi sinensis), a fruit with a sweet and white aril, cultivated mainly in Southeast Asia and possesses anticancer, antibacterial, antioxidant, and other therapeutic properties. It is a delicacy among children. However, an outbreak of acute encephalopathy syndrome (AES) in litchi growing regions during the seasons of litchi ripening and harvesting (May-June) resulted in symptoms of lethargy, weakness, fever, vomiting, seizures, and coma that was most common among malnourished children below 15 years. Upon successful epidemiological studies, it was confirmed that the non-protein amino acids such as hypoglycine A (HGA) and methylenecyclopropylglycine (MCPG) are responsible for the AES outbreak. Most of the underprivileged and malnourished kids with an empty stomach venture into the litchi orchards to savor the fruit during the litchi harvesting season. Their fasting condition results in decreased glucose levels in the blood. The decreased glucose levels trigger glycogenolysis. However, gluconeogenesis takes over glycogenolysis to replenish the glucose levels due to fewer glycogen stores in malnourished children. The toxins are involved in fatty acid oxidation and gluconeogenesis pathways, by blocking several steps in the former process. Depleted glycogen stores and suppression of gluconeogenesis synergistically cause hypoglycemia and accumulation of toxic intermediates from the metabolic pathway leading to metabolic failure. The incidence of AES can be prevented by creating proper awareness among the farmers, vendors and consumers on the importance of adverse effects of litchi fruit when consumed on empty stomach or fasting state. Further, elucidating detailed biochemical pathway of HGA and MCPG toxicity, improving agricultural and public health practices, keeping glucose stores and glucose banks in the areas which are highly prone to litchi induced toxicity are some of the therapeutic measures. This review highlights and discusses the AES incidences, mechanistic pathways involved in litchi fruit toxicity, and corresponding risk factors involved and possible treatment and preventive approaches.

Do Poisonous Plants in Pastures Communicate Their Toxicity? Meta-Study and Evaluation of Poisoning Cases in Central Europe

One of the possible roles of secondary plant metabolites, including toxins, is facilitating plant-animal communication. Lethal cases of pasture poisoning show that the message is not always successfully conveyed. As the focus of poisoning lies in the clinical aspects, the external circumstances of pasture poisoning are widely unknown. To document poisoning conditions in cattle, sheep, goats, and horses on pastures and to compile a checklist of plants involved in either poisoning or co-existence (zero poisoning), published case reports were evaluated as primary sources. The number of affected animal individuals was estimated within abundance classes from 0 to more than 100. The checklist of poisonous plants comprised 52 taxa. Of these, 13 taxa were deemed safe (no reference was found indicating poisoning), 11 taxa were associated with evidence-based zero poisoning (positive list), and 28 taxa were associated with poisoning (negative list). Nine plant taxa caused poisoning in more than 100 animal individuals. Zero poisoning accounted for 40% and poisoning accounted for 60% of a total of 85 cases. Poisoning was most often associated with a limited choice of feed (24.7%), followed by overgrazing (12.9%), seasonally scarce feed (10.6%), and co-ingestion of grass (4.7%). Hunger interferes with plant-animal co-existence, while zero poisoning improves it. In conclusion, poisonous plants in pastures may communicate their toxicity if the animals have enough alternative feed plants. An individual animal might utterly perceive the communication of toxicity by the plant species but be forced to ignore the message owing to a limited choice of feed options.