Corneal Toxicity Secondary to Latex From Asclepias curassavica in a Pediatric Patient.

PURPOSE: To report a case of corneal milkweed toxicity on the corneal endothelium with epithelial damage in a pediatric patient. METHODS: We report a case of a 13-year-old boy who presented to the emergency department with complaints of left eye pain and photophobia after direct corneal exposure to milkweed latex. He was found to have a large corneal epithelial defect and diffuse stromal edema suspected to be secondary to the cardiac glycosides present in the milkweed plant. Clinical examination and course are reported. RESULTS: The patient was seen in the outpatient clinic on multiple visits. His epithelial defect had resolved within 3 days, and all corneal damage had healed within 18 days from injury. He was treated with antibiotic and steroid eye drops. CONCLUSIONS: Corneal exposure to cardiac glycosides from milkweed plants is known to damage the endothelial sodium-potassium pumps and to cause corneal edema and decreased visual acuity. All previously documented case reports of corneal milkweed toxicity are secondary to indirect exposure to the plant's latex. Here, we report the first case of corneal endothelial toxicity because of direct latex inoculation from an Asclepias plant and the first such toxicity reported in a pediatric patient.

Toxicity of the spiny thick-foot Pachypodium.

PREMISE OF THE STUDY: Pachypodium (Apocynaceae) is a genus of iconic stem-succulent and poisonous plants endemic to Madagascar and southern Africa. We tested hypotheses about the mode of action and macroevolution of toxicity in this group. We further hypothesized that while monarch butterflies are highly resistant to cardenolide toxins (a type of cardiac glycoside) from American Asclepias, they may be negatively affected by Pachypodium defenses, which evolved independently. METHODS: We grew 16 of 21 known Pachypodium spp. and quantified putative cardenolides by HPLC and also by inhibition of animal Na+ /K+ -ATPase (the physiological target of cardiac glycosides) using an in vitro assay. Pachypodium extracts were tested against monarch caterpillars in a feeding bioassay. We also tested four Asclepias spp. and five Pachypodium spp. extracts, contrasting inhibition of the cardenolide-sensitive porcine Na+ /K+ -ATPase to the monarch's resistant form. KEY RESULTS: We found evidence for low cardenolides by HPLC, but substantial toxicity when extracts were assayed on Na+ /K+ -ATPases. Toxicity showed phylogenetic signal, and taller species showed greater toxicity (this was marginal after phylogenetic correction). Application of Pachypodium extracts to milkweed leaves reduced monarch growth, and this was predicted by inhibition of the sensitive Na+ /K+ -ATPase in phylogenetic analyses. Asclepias extracts were 100-fold less potent against the monarch compared to the porcine Na+ /K+ -ATPase, but this difference was absent for Pachypodium extracts. CONCLUSIONS: Pachypodium contains potent toxicity capable of inhibiting sensitive and cardenolide-adapted Na+ /K+ -ATPases. Given the monarch's sensitivity to Pachypodium, we suggest that these plants contain novel cardiac glycosides or other compounds that facilitate toxicity by binding to Na+ /K+ -ATPases.

Extensive bilateral corneal edema 6 weeks after cataract surgery: Keratopathy due to Asclepias physocarpa: a case report.

BACKGROUND: Surgeons may be unaware of the ability of plant toxins to cause corneal damage. Therefore, corneal damage following intraocular surgery due to plant toxins may be misdiagnosed as postoperative infection. CASE PRESENTATION: A 74-year-old man presented with hyperemia and reduced visual acuity in both eyes 6 weeks after uneventful cataract surgery. We observed extensive hyperemia and corneal stromal edema with Descemet's folds in both eyes. After obtaining a detailed patient history, we diagnosed plant toxin-induced corneal edema due to Asclepias physocarpa, which can induce corneal edema by inhibiting the Na+/K+ ATPase activity of the corneal endothelium. Antimicrobial and steroid eye drops and an oral steroid were prescribed accordingly. Symptons began to improve on day 3 and had almost completely resolved by day 6. At 1 month, the patient had fully recovered without any sequelae. CONCLUSION: The correct diagnosis was possible in the present case as symptoms were bilateral and the patient was able to report his potential exposure to plant toxins. However, if the symptoms had been unilateral and the patient had been unaware of these toxins, he may have undergone unnecessary surgical interventions to treat non-existent postoperative endophthalmitis.

Diagnose of the ingestion of Asclepias mellodora St. Hil. by sheep through microhistological analysis of their digestive contents / Diagnose da ingestão de Asclepias mellodora St. Hil. por ovinos através da análise micro-histológica de seu conteúdo digestivo

Asclepias mellodora St. Hil. is a native acute toxic species frequent in the grasslands of the Buenos Aires province, Argentina, whose toxicity had not been assessed until now. This study evaluates the minimal lethal dose of this species for sheep, and the possibility of microscopically recognizing its fragments in gastrointestinal contents as a complementary diagnostic tool in necropsies. Three Frisona sheep (average LW=55±4.5 kg) were dosed via an esophageal tube with each one of the following doses of asclepias: 8.0, 5.0, 2.0 and 0.8 g DM.kg LW-1. Sheep poisoned with the three higher doses died between 10 and 85 h after intoxication, but those receiving the lower dose did not. During necropsies we: 1) determined the dry weight of the contents of rumen+reticulum, omasum+abomasum, and large intestine, 2) estimated the percentages of asclepias fragments by microanalysis correcting for digestion effects on fragment recognition, and 3) calculated the total mass of asclepias in the digestive tract of each animal. For the three higher doses, the mass of asclepias identified in the total ingesta was 12.3±3.4 percent of the amount supplied, possibly because of the strong diarrhea its ingestion produced. The percentages of asclepias in rumen+reticulum did not differ from the average quantified for the entire tract. The results of this study indicate that the minimal lethal doses of asclepias for sheep is between 2.0 and 0.8g DMÀkg LW-1, and that the microhistological analysis of the rumen+reticulum, the easiest region to sample, can be used to confirm the ingestion of this toxic species, although the estimated percentage will be not a good estimator of the ingested percentage.

Asclepias mellodora St. Hil. é uma espécie nativa de aguda toxicidade, frequente nos campos da província de Buenos Aires, Argentina. A sua toxicidade não foi avaliada até agora. Este estudo avalia a dose mínima letal desta espécie, para os ovinos, bem como a possibilidade de reconhecer microscopicamente seus fragmentos no conteúdo gastrointestinal como uma ferramenta complementar de diagnóstico em necropsias. Três ovinos Frisona (PV média = 55±4,5 kg) foram dosados através de uma sonda esofágica em cada uma das seguintes doses de Asclepias: 8,0, 5,0, 2,0 e 0,8 g DM.kg PV-1. Ovinos intoxicados com as três maiores doses morreram entre 10-85 h após a intoxicação, mas não aqueles que receberam a dose menor. Durante as necropsias se: 1) determinou o peso seco do conteúdo do rúmen + retículo, omaso + abomaso e intestino grosso, 2) estimou as porcentagens de fragmentos de Asclepias por microanálise, fazendo a correção para efeitos de digestão no reconhecimento dos fragmentos, e 3) calculou a massa total de Asclepias no trato digestivo de cada animal. Para as três doses maiores, a massa de Asclepias identificada na ingesta total foi de 12,3±3,4 por cento da quantidade fornecida, possivelmente por causa da forte diarréia produzida pela sua ingestão. As porcentagens de Asclepias no rúmen + retículo não diferiram da média quantificada para o trato completo. Os resultados deste estudo indicam que a dose letal mínima de Asclepias em ovinos é de entre 2,0 e 0,8 g kg PV ò DM-1, e que a análise micro-histológica do rúmen + retículo, a região mais fácil de amostrar, pode ser usada para confirmar a ingestão desta espécie tóxica, embora a percentagem estimada não será um bom estimador da porcentagem ingerida.