Fatal Ricin Toxicosis in a Puppy Confirmed by Liquid Chromatography/Mass Spectrometry when Using Ricinine as a Marker

Proteomic Methods of Detection and Quantification of Protein Toxins

Biological toxins are a heterogeneous group of compounds that share commonalities with biological and chemical agents. Among them, protein toxins represent a considerable, diverse set. They cover a broad range of molecular weights from less than 1000 Da to more than 150 kDa. This review aims to compare conventional detection methods of protein toxins such as in vitro bioassays with proteomic methods, including immunoassays and mass spectrometry-based techniques and their combination. Special emphasis is given to toxins falling into a group of selected agents, according to the Centers for Disease Control and Prevention, such as Staphylococcal enterotoxins, Bacillus anthracis toxins, Clostridium botulinum toxins, Clostridium perfringens epsilon toxin, ricin from Ricinus communis, Abrin from Abrus precatorius or control of trade in dual-use items in the European Union, including lesser known protein toxins such as Viscumin from Viscum album. The analysis of protein toxins and monitoring for biological threats, i.e., the deliberate spread of infectious microorganisms or toxins through water, food, or the air, requires rapid and reliable methods for the early identification of these agents.

Serial ricinine levels in serum and urine after ricin intoxication

Ricinine is an alkaloid present in the castor bean plant (Ricinus communis) that can be used as a biomarker for ricin poisoning. Serial ricinine levels are reported in the serum and urine of a patient suffering from intentional ricin intoxication. The patient was brought to the hospital 4 h after injection and oral intake of a castor bean extract, but died 38 h later, despite intensive medical care. Ricinine was isolated from the samples by solid-phase extraction and quantitatively determined by isotopic dilution liquid chromatography-mass spectrometry. The ricinine level in serum declined from 33 to 23 ng/mL between 10 and 29 h post-exposure. Three urine samples collected from 12 to 41 h after ricin intoxication showed ricinine concentrations in the range of 20-58 ng/mL. The creatinine corrected values (21-30 µg/g) indicated a concentration-time profile with a maximum ricinine level in urine between 12 and 29 h after exposure.

Analysis of a ricin biomarker, ricinine, in 989 individual human urine samples

Ricinine (3-cyano-4-methoxy-N-methyl-2-pyridone) is a urinary biomarker that can be measured to confirm human exposure to castor bean products such as ricin. Because many consumer products contain castor oil, another castor bean product, ricinine may be detectable in the general population. The following study characterized urinary ricinine concentrations from 989 individuals who were presumed to be unexposed to ricin. An automated diagnostic method was utilized to simplify the analysis of this large sample set. Sample preparation included a 96-well polystyrene divinylbenzene high throughput extraction and preconcentration step. Purified samples were analyzed by an efficient dual column, reversed-phase liquid chromatography separation and (13)C-isotope dilution tandem mass spectrometry. In this convenience sample set, only 1.2% of the urine specimens had detectable amounts of ricinine, randomly distributed between 0.186 and 4.15 ng/mL.

Ricinus communis intoxications in human and veterinary medicine-a summary of real cases

Accidental and intended Ricinus communis intoxications in humans and animals have been known for centuries but the causative agent remained elusive until 1888 when Stillmark attributed the toxicity to the lectin ricin. Ricinus communis is grown worldwide on an industrial scale for the production of castor oil. As by-product in castor oil production ricin is mass produced above 1 million tons per year. On the basis of its availability, toxicity, ease of preparation and the current lack of medical countermeasures, ricin has gained attention as potential biological warfare agent. The seeds also contain the less toxic, but highly homologous Ricinus communis agglutinin and the alkaloid ricinine, and especially the latter can be used to track intoxications. After oil extraction and detoxification, the defatted press cake is used as organic fertilizer and as low-value feed. In this context there have been sporadic reports from different countries describing animal intoxications after uptake of obviously insufficiently detoxified fertilizer. Observations in Germany over several years, however, have led us to speculate that the detoxification process is not always performed thoroughly and controlled, calling for international regulations which clearly state a ricin threshold in fertilizer. In this review we summarize knowledge on intended and unintended poisoning with ricin or castor seeds both in humans and animals, with a particular emphasis on intoxications due to improperly detoxified castor bean meal and forensic analysis.

Treatment of aseptic dogs with hemorrhagic gastroenteritis with amoxicillin/clavulanic acid: a prospective blinded study

BACKGROUND

Antibiotics generally are recommended to treat hemorrhagic gastroenteritis (HGE). Inappropriate use of antibiotics may promote risk of antimicrobial resistance and unnecessary adverse drug reactions. The necessity of antimicrobial therapy in dogs with HGE has not been demonstrated.

OBJECTIVE

The purpose of this prospective, placebo-controlled, blinded study was to evaluate whether treatment with amoxicillin/clavulanic acid improves the clinical course and outcome of HGE in dogs that show no signs of sepsis.

ANIMALS

The study included 60 dogs diagnosed with HGE between 2007 and 2009 at the Clinic of Small Animal Medicine, LMU University of Munich, Germany. The inclusion criterion was the presence of acute hemorrhagic diarrhea (<3 days). Dogs pretreated with antibiotics, with signs of sepsis, or diagnosed with any disease known to cause bloody diarrhea were excluded from the study.

METHODS

Patients were randomly divided into treatment (amoxicillin/clavulanic acid for 7 days) and placebo groups. To evaluate treatment efficacy, severity of clinical signs (based on a newly developed HGE index), duration of hospitalization, and mortality rate were compared between the 2 groups.

RESULTS

Fifty-three of 60 dogs completed the study. No significant difference between treatment groups concerning mortality rate, dropout rate, duration of hospitalization, or severity of clinical signs, either on any individual day or over the course of disease, was observed.

CONCLUSIONS AND CLINICAL IMPORTANCE

In some dogs with HGE that show no signs of sepsis, antibiotics may not change the case outcome or time to recovery.

Ricin toxicokinetics and its sensitive detection in mouse sera or feces using immuno-PCR

BACKGROUND

Ricin (also called RCA-II or RCA(60)), one of the most potent toxins and documented bioweapons, is derived from castor beans of Ricinus communis. Several in vitro methods have been designed for ricin detection in complex food matrices in the event of intentional contamination. Recently, a novel Immuno-PCR (IPCR) assay was developed with a limit of detection of 10 fg/ml in a buffer matrix and about 10-1000-fold greater sensitivity than other methods in various food matrices.

METHODS AND FINDINGS

In order to devise a better diagnostic test for ricin, the IPCR assay was adapted for the detection of ricin in biological samples collected from mice after intoxication. The limit of detection in both mouse sera and feces was as low as 1 pg/ml. Using the mouse intravenous (iv) model for ricin intoxication, a biphasic half-life of ricin, with a rapid t(1/2)α of 4 min and a slower t(1/2)β of 86 min were observed. The molecular biodistribution time for ricin following oral ingestion was estimated using an antibody neutralization assay. Ricin was detected in the blood stream starting at approximately 6-7 h post- oral intoxication. Whole animal histopathological analysis was performed on mice treated orally or systemically with ricin. Severe lesions were observed in the pancreas, spleen and intestinal mesenteric lymph nodes, but no severe pathology in other major organs was observed.

CONCLUSIONS

The determination of in vivo toxicokinetics and pathological effects of ricin following systemic and oral intoxication provide a better understanding of the etiology of intoxication and will help in the future design of more effective diagnostic and therapeutic methods.

Lethal ricin intoxication in two adult dogs: toxicologic and histopathologic findings

Two adult dogs with the same owner were intoxicated by ingestion of fertilizer composed of residual plant material of the castor bean plant (Ricinus communis L.). Both dogs died within 2 and 3 days, respectively, after the first signs of vomiting and abundant hemorrhagic diarrhea. Toxicologic and histopathologic examinations were performed on different organs. Histopathologic examination of the kidneys revealed tubular degeneration and necrosis and membranous glomerulonephritis. Additionally, myocardial degeneration with localized inflammation, lymphoid necrosis, and depletion in the spleen and mesenteric lymph nodes and hemorrhagic ulcerative gastroenteritis were found. The 2 cases could be used to elucidate the lethal dose of ricin and the histopathologic lesions in dogs.

Fetal death of dogs after the ingestion of a soil conditioner

Castor beans (Ricinus communis) contain ricin, which is one of the most toxic substances of plant origin. Ricin toxicosis has been reported in different countries with usually ingestion of castor beans or plants in both animals and humans. However, ricin toxicosis by ingestion of some products containing castor oil cake has rarely been reported. This paper describes outbreaks of dog death by ricin toxicosis after accidental ingestion of the same soil conditioner. Fifteen dogs showed toxic symptoms such as severe vomiting, abdominal pain and hemorrhagic diarrhea, and then thirteen dogs died in a few days. The soil conditioner dogs ingested consisted of 10% castor oil cake containing ricin. On the basis of clinical signs, laboratory and pathologic findings, a diagnosis of ricin toxicosis was established in the present case. In comparison with previous cases by ingestion of castor beans, the dogs' morbidity was very high in the present case. The ingestion of castor oil cake may be more dangerous to life than the castor beans. It is because mortality by ingestion of castor beans depends on the degree of mastication of the beans, whereas ricin in oil cake is easily absorbed from the stomach and the intestines. As ricin is a heat-labile toxin, products containing ricin or oil cake should be properly treated with heat and have written caution sentences about toxicosis, and be kept out of reach of domestic animals and children.

Suicidal death after injection of a castor bean extract (Ricinus communis L.)

The castor bean plant (Ricinus communis L.) or wonder tree is cultivated in many countries as an ornamental annual plant in gardens. The highest concentration of the lectin ricin is present in the seeds and pods. Ricin is considered as one of the most toxic natural poisons. Ricinine is a piperidine alkaloidal toxin present in castor bean and is described as a biomarker for the exposure to ricin. A case report is presented of a 49-year-old man who committed suicide by intravenous and subcutaneous injection of a castor bean extract. He was brought to the emergency department 24 h after injecting himself. On admission, the patient was conscious and he presented with a history of nausea, vomiting, diarrhoea, dyspnoea, vertigo and muscular pain. Despite symptomatic and supportive intensive care, the man died 9 h after admission due to multiorgan failure. A body external examination was performed. Blood, urine, vitreous humour and the castor bean extract were submitted to the laboratory for toxicological analysis. The identification of ricinine in the extract was performed by solid phase extraction in combination with full-scan gas chromatography/mass spectrometry, high-performance liquid chromatography with photodiode array detection and liquid chromatography/mass spectrometry operated in the full-scan mode, respectively. An extraction procedure with Oasis HLB solid phase extraction cartridges was applied. Chromatography was achieved using a Symmetry C18 column using a gradient mode with 0.15% formic acid and 0.15% formic acid in acetonitrile as mobile phase. Exposure to the castor bean extract was confirmed by identification of the biomarker ricinine in blood, urine and vitreous humour using solid phase extraction and liquid chromatography tandem mass spectrometry with electro spray source in positive ionization mode. Multiple reaction monitoring was used for specific detection. To the authors' knowledge, it is the first time that ricinine has been identified in vitreous humour in a case of castor bean poisoning. Based on the clinical symptoms and the results of the toxicological analysis, we concluded that death was caused by intoxication with plant toxins originated from R. communis L.

Mass spectrometry in biodefense

Potential agents for biological attacks include both microorganisms and toxins. In mass spectrometry (MS), rapid identification of potential bioagents is achieved by detecting the masses of unique biomarkers, correlated to each agent. Currently, proteins are the most reliable biomarkers for detection and characterization of both microorganisms and toxins, and MS-based proteomics is particularly well suited for biodefense applications. Confident identification of an organism can be achieved by top-down proteomics following identification of individual protein biomarkers from their tandem mass spectra. In bottom-up proteomics, rapid digestion of intact protein biomarkers is again followed by MS/MS to provide unambiguous bioagent identification and characterization. Bioinformatics obviates the need for culturing and rigorous control of experimental variables to create and use MS fingerprint libraries for various classes of bioweapons. For specific applications, MS methods, instruments and algorithms have also been developed for identification based on biomarkers other than proteins and peptides.