The In Vitro Cytotoxic Effects of Ionophore Exposure on Selected Cytoskeletal Proteins of C2C12 Myoblasts.

Carboxylic ionophores, such as monensin, salinomycin and lasalocid, are polyether antibiotics used widely in production animals for the control of coccidiosis, as well as for the promotion of growth and feed efficiency. Although the benefits of using ionophores are undisputed, cases of ionophore toxicosis do occur, primarily targeting the cardiac and skeletal muscles of affected animals. The 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyl tetrazolium bromide (MTT) viability assay was used to determine the cytotoxicity of monensin, salinomycin and lasalocid on mouse skeletal myoblasts (C2C12). Immunocytochemistry and immunofluorescent techniques were, in turn, performed to investigate the effects of the ionophores on the microfilament, microtubule and intermediate filament, i.e., desmin and synemin networks of the myoblasts. Monensin was the most cytotoxic of the three ionophores, followed by salinomycin and finally lasalocid. Monensin and salinomycin exposure resulted in the aggregation of desmin around the nuclei of affected myoblasts. The synemin, microtubule and microfilament networks were less affected; however, vesicles throughout the myoblast's cytoplasm produced gaps within the microtubule and, to a limited extent, the synemin and microfilament networks. In conclusion, ionophore exposure disrupted desmin filaments, which could contribute to the myofibrillar degeneration and necrosis seen in the skeletal muscles of animals suffering from ionophore toxicosis.

Copper induces cell death by targeting lipoylated TCA cycle proteins.

Copper is an essential cofactor for all organisms, and yet it becomes toxic if concentrations exceed a threshold maintained by evolutionarily conserved homeostatic mechanisms. How excess copper induces cell death, however, is unknown. Here, we show in human cells that copper-dependent, regulated cell death is distinct from known death mechanisms and is dependent on mitochondrial respiration. We show that copper-dependent death occurs by means of direct binding of copper to lipoylated components of the tricarboxylic acid (TCA) cycle. This results in lipoylated protein aggregation and subsequent iron-sulfur cluster protein loss, which leads to proteotoxic stress and ultimately cell death. These findings may explain the need for ancient copper homeostatic mechanisms.

Natural and experimental salinomycin poisoning associated with the use of florfenicol in pigs / Intoxicação natural e experimental por salinomicina associada ao uso de florfenicol em suínos

This study describes the spontaneous and experimental salinomycin poisoning associated with the use of florfenicol and warns about the effects of the administration of antibiotics to animals that receive ionophores in the feed as growth promoters. A batch with 1,200 finishing pigs fed a diet containing 30ppm of salinomycin received florfenicol (60ppm via feed) to control respiratory diseases. Twenty-seven pigs had difficulty walking, tip-toe walking, muscle tremors, and anorexia seven days after the start of treatment. Twenty-two animals died, 10 recovered, and two were sent to the Laboratory of Animal Pathology of CAV-UDESC to be necropsied. The experimental reproduction of the disease was carried out to clarify the possible influence of florfenicol on salinomycin poisoning using 12 pigs divided into four groups with three animals each, treated for 16 days with diets containing no additives (Group 1), 50ppm of salinomycin (Group 2), 40ppm of florfenicol (Group 3), and 50ppm of salinomycin and 40ppm of florfenicol (Group 4). Only animals in Group 4 became ill. The clinical disease was reproduced from the ingestion of 24.67mg/kg/LW of salinomycin and 19.74mg/kg/LW of florfenicol. Both natural and experimental salinomycin poisoning associated with the use of florfenicol caused a condition of myopathy characterized in histology by hyaline degeneration and floccular necrosis of skeletal fibers, with macrophage infiltrate, associated with the figures of regeneration in skeletal muscles and multifocal areas of the proliferation of fibroblasts, being more intense in the longissimus dorsi and semimembranosus muscles. Therefore, florfenicol can cause the accumulation of ionophore salinomycin in the animal organism, resulting in a condition of toxic myopathy.(AU)

O presente trabalho descreve as intoxicações espontânea e experimental por salinomicina associada ao uso de florfenicol e alerta sobre os efeitos da administração de antibióticos aos animais que recebem ionóforos na ração como promotores de crescimento. Um lote com 1.200 suínos em fase de terminação, alimentados com ração contendo 30ppm de salinomicina, recebeu florfenicol (60ppm via ração) para o controle de doenças respiratórias. Sete dias após o início do tratamento, 27 suínos apresentaram dificuldade de locomoção, "caminhar em brasa", tremores musculares e anorexia. Vinte e dois animais morreram, 10 recuperaram-se e dois foram encaminhados ao Laboratório de Patologia Animal (CAV-UDESC) para serem necropsiados. Para esclarecer a possível influência do florfenicol na toxicidade da salinomicina foi realizada a reprodução experimental da doença utilizando 12 suínos, divididos em 4 grupos com 3 animais cada, tratados por 16 dias com rações contendo: Grupo 1 = sem aditivos, Grupo 2 = 50ppm de salinomicina, Grupo 3 = 40ppm de florfenicol e Grupo 4 = 50ppm de salinomicina e 40ppm de florfenicol. Somente os animais do Grupo 4 adoeceram. A doença clínica foi reproduzida a partir da ingestão de 24,67mg/kg/PV de salinomicina e 19,74 mg/kg/PV de florfenicol. Tanto a intoxicação natural quanto a experimental por salinomicina associada ao uso de florfenicol provocaram um quadro de miopatia caracterizado na histologia por degeneração hialina e necrose flocular das fibras esqueléticas, com infiltrado macrofágico, associada às figuras de regeneração na musculatura esquelética e áreas multifocais de proliferação de fibroblastos, sendo mais intensas nos músculos longissimus dorsi e semimembranoso. Conclui-se que, o florfenicol tem a capacidade de ocasionar o acúmulo do ionóforo salinomicina no organismo animal, resultando em um quadro de miopatia tóxica.(AU)

Natural and experimental salinomycin poisoning associated with the use of florfenicol in pigs / Intoxicação natural e experimental por salinomicina associada ao uso de florfenicol em suínos

This study describes the spontaneous and experimental salinomycin poisoning associated with the use of florfenicol and warns about the effects of the administration of antibiotics to animals that receive ionophores in the feed as growth promoters. A batch with 1,200 finishing pigs fed a diet containing 30ppm of salinomycin received florfenicol (60ppm via feed) to control respiratory diseases. Twenty-seven pigs had difficulty walking, tip-toe walking, muscle tremors, and anorexia seven days after the start of treatment. Twenty-two animals died, 10 recovered, and two were sent to the Laboratory of Animal Pathology of CAV-UDESC to be necropsied. The experimental reproduction of the disease was carried out to clarify the possible influence of florfenicol on salinomycin poisoning using 12 pigs divided into four groups with three animals each, treated for 16 days with diets containing no additives (Group 1), 50ppm of salinomycin (Group 2), 40ppm of florfenicol (Group 3), and 50ppm of salinomycin and 40ppm of florfenicol (Group 4). Only animals in Group 4 became ill. The clinical disease was reproduced from the ingestion of 24.67mg/kg/LW of salinomycin and 19.74mg/kg/LW of florfenicol. Both natural and experimental salinomycin poisoning associated with the use of florfenicol caused a condition of myopathy characterized in histology by hyaline degeneration and floccular necrosis of skeletal fibers, with macrophage infiltrate, associated with the figures of regeneration in skeletal muscles and multifocal areas of the proliferation of fibroblasts, being more intense in the longissimus dorsi and semimembranosus muscles. Therefore, florfenicol can cause the accumulation of ionophore salinomycin in the animal organism, resulting in a condition of toxic myopathy.

O presente trabalho descreve as intoxicações espontânea e experimental por salinomicina associada ao uso de florfenicol e alerta sobre os efeitos da administração de antibióticos aos animais que recebem ionóforos na ração como promotores de crescimento. Um lote com 1.200 suínos em fase de terminação, alimentados com ração contendo 30ppm de salinomicina, recebeu florfenicol (60ppm via ração) para o controle de doenças respiratórias. Sete dias após o início do tratamento, 27 suínos apresentaram dificuldade de locomoção, "caminhar em brasa", tremores musculares e anorexia. Vinte e dois animais morreram, 10 recuperaram-se e dois foram encaminhados ao Laboratório de Patologia Animal (CAV-UDESC) para serem necropsiados. Para esclarecer a possível influência do florfenicol na toxicidade da salinomicina foi realizada a reprodução experimental da doença utilizando 12 suínos, divididos em 4 grupos com 3 animais cada, tratados por 16 dias com rações contendo: Grupo 1 = sem aditivos, Grupo 2 = 50ppm de salinomicina, Grupo 3 = 40ppm de florfenicol e Grupo 4 = 50ppm de salinomicina e 40ppm de florfenicol. Somente os animais do Grupo 4 adoeceram. A doença clínica foi reproduzida a partir da ingestão de 24,67mg/kg/PV de salinomicina e 19,74 mg/kg/PV de florfenicol. Tanto a intoxicação natural quanto a experimental por salinomicina associada ao uso de florfenicol provocaram um quadro de miopatia caracterizado na histologia por degeneração hialina e necrose flocular das fibras esqueléticas, com infiltrado macrofágico, associada às figuras de regeneração na musculatura esquelética e áreas multifocais de proliferação de fibroblastos, sendo mais intensas nos músculos longissimus dorsi e semimembranoso. Conclui-se que, o florfenicol tem a capacidade de ocasionar o acúmulo do ionóforo salinomicina no organismo animal, resultando em um quadro de miopatia tóxica.

Ionophore Toxin Maduramicin Produces Haff Disease-Like Rhabdomyolysis in a Mouse Model.

Maduramicin is a toxic ionophore antibiotic that is isolated from Streptomyces, frequently occurring in an aquatic environment. To understand the potential role of maduramicin in crayfish consumption related Haff disease, a mouse model was established in this study. Two exposure routes of maduramicin in the abdominal muscle and the hepatopancreas tissue homogenates of crayfish were given intragastrically to mice in different doses for seven days. Action changes, clinical symptoms, feed consumption, body weight, blood biochemistry, and histopathology examination of mice were observed and analyzed. In the natural exposure group, relatively low concentration of maduramicin in crayfish muscle and hepatopancreas had no obvious effects on mental state, body weight, blood biochemical indexes, or histologic appearance. However, in the artificial exposure group, with increasing concentrations, maduramicin in crayfish muscle and hepatopancreas homogenates both induced mental sluggishness and weight loss of mice. Blood biochemical examination showed that 3.5 mg·kg-1 and 7 mg·kg-1 maduramicin in crayfish tissue homogenates significantly increased levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), lactate dehydrogenase (LDH), and creatine kinase (CK). Additionally, histopathological examination showed that multiple organs were damaged by maduramicin, including degeneration of liver cells, shedding of renal epithelial cells, and disturbance and partial lysis of myocardial and skeletal muscle filaments in the mice. In summary, maduramicin may not cause Haff disease through contamination of the aquatic environment under normal conditions. Maduramicin can be used as a potential toxin tool to establish a rhabdomyolysis disease animal model for drug development.

Effect of the veterinary ionophore monensin on the structure and activity of a tropical soil bacterial community.

Monensin (MON) is a coccidiostat used as a growth promoter that can reach the environment through fertilization with manure from farm animals. To verify whether field-relevant concentrations of this drug negatively influence the structure and activity of tropical soil bacteria, plate counts, CO2 efflux measurements, phospholipid fatty acids (PLFA) and community-level physiological profiling (CLPP) profiles were obtained for soil microcosms exposed to 1 or 10 mg kg-1 of MON across 11 days. Although 53% (1 mg kg-1) to 40% (10 mg kg-1) of the MON concentrations added to the microcosms dissipated within 5 days, a subtle concentration-dependent decrease in the number of culturable bacteria (<1 log CFU g-1), reduced (-20 to -30%) or exacerbated (+25%) soil CO2 effluxes, a marked shift of non-bacterial fatty acids, and altered respiration of amines (1.22-fold decrease) and polymers (1.70-fold increase) were noted in some of the treatments. These results suggest that MON quickly killed some microorganisms and that the surviving populations were selected and metabolically stimulated. Consequently, MON should be monitored in agronomic and environmental systems as part of One Health efforts.

Cytotoxicity Study of Ionophore-Based Membranes: Toward On-Body and in Vivo Ion Sensing.

We present the most complete study to date comprising in vitro cytotoxicity tests of ion-selective membranes (ISMs) in terms of cell viability, proliferation, and adhesion assays with human dermal fibroblasts. ISMs were prepared with different types of plasticizers and ionophores to be tested in combination with assays that focus on the medium-term and long-term leaching of compounds. Furthermore, the ISMs were prepared in different configurations considering (i) inner-filling solution-type electrodes, (ii) all-solid-state electrodes based on a conventional drop-cast of the membrane, (iii) peeling after the preparation of a wearable sensor, and (iv) detachment from a microneedle-based sensor, thus covering a wide range of membrane shapes. One of the aims of this study, other than the demonstration of the biocompatibility of various ISMs and materials tested herein, is to create an awareness in the scientific community surrounding the need to perform biocompatibility assays during the very first steps of any sensor development with an intended biomedical application. This will foster meeting the requirements for subsequent on-body application of the sensor and avoiding further problems during massive validations toward the final in vivo use and commercialization of such devices.

Retrospective analysis of cattle poisoning in Argentina (2000-2013)

A retrospective analysis (2000 to 2013) of cattle poisoning caused by toxic plants and other compounds was carried out in the Pampas region of Argentina by the Animal Health Group of INTA-EEA, Balcarce. During this period, 1263 reports of diseases of different etiologies (infectious, parasitic, toxic, metabolic and miscellaneous) were recorded in cattle, by collecting anamnestic, clinical and pathological information. A toxic etiology was diagnosed in 21.1% of these reports. Iatrogenic poisoning caused by ionophores was the most frequently recorded etiology. Consumption of toxic plants (Wedelia glauca, Solanum glaucophyllum, among others), mycotoxins (Claviceps purpurea, Claviceps paspali, Epichloë coenophiala, among others), and plants producing cyanide and nitrates/nitrites were also commonly diagnosed. The high frequency of toxic episodes and the difficulties in their diagnosis by practitioners in our livestock production systems emphasizes the importance of this report.(AU)

Antimicrobial potential of the ionophore monensin on freshwater biofilm bacteria.

Microorganisms play key roles in stream ecosystems, but comparatively little is known about the resilience of freshwater bacterial communities and their susceptibility to the chemical by-products of agricultural land use. Antibiotics used in the agricultural sector are of particular concern and have been detected in waterways associated with agricultural land. Despite widespread agricultural intensification globally and the sector's high antibiotic use, the effects of agricultural antibiotic by-products on stream microbial communities have yet to be characterised. We investigated the impacts of the antibiotic monensin on microbial biofilm communities in a simulated contamination event using streamside-replicated channels. A 24-h pulse experiment in flow channels precolonised by stream biofilm microbial communities contrasted the effects of monensin concentrations ranging from realistic to extreme toxicity levels (1-550 ug L(-1)). Biofilm community composition was characterised immediately before and after the pulse for several weeks using automated ribosomal intergenic spacer analysis. Despite applying acutely toxic levels of monensin, only limited effects to biofilm community composition were detected immediately after antibiotic application, and these disappeared within 4 days. Rather, temporal factors drove biofilm differences, highlighting the overriding importance of wider, catchment-level, physiochemical hydrological influences on structuring freshwater biofilm communities, as opposed to localised and sporadic agricultural surface runoff contamination events containing antibiotics.

Beauvericin-induced cytotoxicity via ROS production and mitochondrial damage in Caco-2 cells.

The cytotoxicity of beauvericin (BEA) on human colon adenocarcinoma (Caco-2) cells was studied as a function of time. Moreover, the oxidative damage and cell death endpoints were monitored after 24, 48 and 72 h. After BEA exposure, the IC50 values ranged from 1.9 ± 0.7 to 20.6 ± 6.9 µM. A decrease in reduced glutathione (GSH; 31%) levels, as well as an increase in oxidized glutathione (GSSG, 20%) was observed. In the presence of BEA, reactive oxygen species (ROS) level was highly increased at an early stage with the highest production of 2.0-fold higher than the control that was observed at 120 min. BEA induced cell death by mitochondria-dependent apoptotic process with loss of the mitochondrial membrane potential (ΔΨm; 9% compared to the control), increase in LPO level (from 120% to 207% compared to the control) and reduced G0/G1 phase, with an arrest in G2/M, in a dose and time-dependent manner. Cell proliferation, apoptosis and ΔΨm determined, were in a dose- time-dependent manner. Moreover, DNA damage was observed after 12.0 µM concentration. This study demonstrated that oxidative stress is one of the mechanism involved in BEA toxicity, moreover apoptosis induction and loss of ΔΨm contribute to its cytotoxicity in Caco-2 cells.

Toxicity of the ionophore antibiotic lasalocid to soil-dwelling invertebrates: avoidance tests in comparison to classic sublethal tests.

Lasalocid is a veterinary ionophore antibiotic used for prevention and treatment of coccidiosis in poultry. It enters the environment with the use of contaminated manure on agricultural land. Despite its extensive use, the effects of lasalocid on non-target soil organisms are poorly explored. We used classical subleathal ecotoxicity tests to assess the effects of lasalocid on earthworms (Eisenia andrei) and isopods (Porcellio scaber) and compared the results with tests using avoidance behaviour as the endpoint. The results showed that avoidance is a much more sensitive endpoint. For earthworms, EC50 for avoidance (12.3 mg kg(-1) dry soil) was more than five times lower than EC50 for reproduction (69.6 mg kg(-1) dry soil). In isopods the sensitivity of the behavioural response test was even higher. While the highest lasalocid concentration 202 mg kg(-1) had no significant effects on isopod growth or survival, already the lowest used concentration in the behavioural assay (4.51 mg kg(-1)) caused significant impact on isopod behaviour. Using the avoidance test results for calculating the predicted no-effect concentration (PNEC) of lasalocid to soil invertebrates, the value is close to the predicted environmental concentration (PEC). This indicates that the use of lasalocid-contaminated manure could potentially impair the habitat function of agricultural soils.

Polyether ionophores-promising bioactive molecules for cancer therapy.

The natural polyether ionophore antibiotics might be important chemotherapeutic agents for the treatment of cancer. In this article, the pharmacology and anticancer activity of the polyether ionophores undergoing pre-clinical evaluation are reviewed. Most of polyether ionophores have shown potent activity against the proliferation of various cancer cells, including those that display multidrug resistance (MDR) and cancer stem cells (CSC). The mechanism underlying the anticancer activity of ionophore agents can be related to their ability to form complexes with metal cations and transport them across cellular and subcellular membranes. Increasing evidence shows that the anticancer activity of polyether ionophores may be a consequence of the induction of apoptosis leading to apoptotic cell death, arresting cell cycle progression, induction of the cell oxidative stress, loss of mitochondrial membrane potential, reversion of MDR, synergistic anticancer effect with other anticancer drugs, etc. Continued investigation of the mechanisms of action and development of new polyether ionophores and their derivatives may provide more effective therapeutic drugs for cancer treatments.

Tissue Doppler imaging and 2-dimensional speckle tracking of left ventricular function in horses exposed to lasalocid.

BACKGROUND: Tissue Doppler imaging (TDI) and 2-dimensional speckle tracking (2DST) can quantify left ventricular (LV) function in horses. OBJECTIVES: To evaluate LV function by TDI and 2DST in horses with myocardial dysfunction after accidental ionophore intoxication. ANIMALS: Sixty-seven horses exposed to lasalocid in feed. METHODS: Prospective study. Horses were included in the study if a full cardiac examination was performed, consisting of determination of cardiac troponin I (cTnI), electrocardiography, and echocardiography. By TDI, radial systolic velocity and strain were measured. By 2DST, circumferential (SC) and radial (SR) strain at papillary muscle and chordal level and longitudinal (SL) strain were measured. RESULTS: Twenty horses showed signs of myocardial injury. Forty-nine examinations were performed on these horses between day 30 and 490 after suspected onset of exposure. Five horses had increased cTnI and ventricular tachycardia and 15 had increased cTnI without ventricular tachycardia. Horses with mild myocardial damage showed few significant differences compared with a control group. Horses with severe myocardial damage showed severely decreased TDI, 2DST and fractional shortening measurements (P < .05), indicating impaired LV function. Long-term follow-up of 2 surviving horses demonstrated full recovery in 1 horse and permanent myocardial fibrosis in the other. The lowest measurements per horse (n = 20) for all TDI measurements, SL, SR at chordal level, and FS correlated significantly with maximal cTnI (P < .05). Over all examinations (n = 49), TDI and 2DST measurements correlated well with FS (P < .05). CONCLUSIONS AND CLINICAL IMPORTANCE: The TDI and 2DST measurements allowed accurate detection and quantification of LV dysfunction in horses exposed to lasalocid.

Neurotoxicity induced by okadaic acid in the human neuroblastoma SH-SY5Y line can be differentially prevented by α7 and ß2* nicotinic stimulation.

A good model of neuronal death that reproduces the characteristic tau (τ) hyperphosphorylation of Alzheimers disease is the use of okadaic acid (OA). The aim of this study was to determine the contribution of α7 and ß2* nicotinic acetylcholine receptor (nAChR) subtypes to neuroprotection against OA in the SH-SY5Y cell line by using the selective α7 and ß2* nAChR agonists PNU 282987 and 5-Iodo-A85380, respectively. The results of this study show that both α7 and ß2* nAChR can afford neuroprotection against OA-induced neurotoxicity. Protection mediated by α7 nAChRs was independent of Ca(2+) and involved the intracellular signaling pathway Janus Kinase-2/Phosphatidylinositol-3-kinase/Akt. When Ca(2+) entry was promoted through the α7 nAChR by using the α7-selective positive allosteric modulator PNU 120596, protection was lost. By contrast, protection mediated by ß2* nAChRs was Ca(2+) dependent and implicated the signaling pathways PI3K/Akt and extracellular regulated kinase 1/2. Both α7 and ß2* nAChR activation converged on downregulation of GSK-3ß and reduction of τ phosphorylation in cells undergoing cell death induced by OA. Therefore, targeting nAChR could offer a strategy for reducing neurodegeneration secondary to hyperphosphorylation of protein τ.

Ionophore toxicity and tolerance.

The rapid growth of the biofuels industry in the Midwest in the past 10 years has created an increased supply of corn coproduct feed for animals. This article discusses the tolerance and toxicology of biofuels coproducts in ruminants, including polioencephalomalacia, sulfur toxicosis, sulfur metabolism, mycotoxins, antibiotic residue, and biodiesel by-product toxicosis.

Intoxicação espontânea por antibióticos ionóforos em ovinos no Rio Grande do Sul / Spontaneous poisoning by ionophores in sheep in Rio Grande do Sul, Brazil

Um surto de intoxicação espontânea por antibióticos ionóforos em ovinos da região Central do Rio Grande do Sul é descrito. Os 16 ovinos afetados estavam em campo nativo e ingeriram acidentalmente um aditivo alimentar para frangos contendo 250g/kg de narasina. Os sinais clínicos consistiam de fraqueza, incoordenação, dispnéia, secreção nasal, decúbito e morte em poucas horas. Um ovino apresentou urina escura. Macroscopicamente havia ascite, hidrotórax, edema pulmonar e palidez hepática. Discreto grau de degeneração muscular na musculatura esquelética dos membros pélvicos e torácicos foi observado histologicamente. O diagnóstico de intoxicação por narasina foi realizado com base no histórico (ingestão de aditivo alimentar contendo narasina) e nos achados clinico-patológicos.

An outbreak of spontaneous ionophore toxicity in sheep grazing in native pasture in Rio Grande do Sul state, Brazil is described. Sixteen sheep which had accidental access to a chicken feed additive containing 250g/kg of narasin were affected. Clinical signs consisted of weakness, incoordination, dyspnea, nasal discharge, recumbency, and death in a few hours. One sheep showed dark red urine. Grossly there were ascites, hydrothorax, pulmonary edema, and hepatic paleness. Discrete skeletal muscle degeneration was observed histologically in the muscles of the pelvic and thoracic limbs. The diagnostic of narasin toxicosis was based on history (ingestion of feed additive containing narasin), clinical, and pathological findings.

Measurement of plasma cardiac troponin I concentration by use of a point-of-care analyzer in clinically normal horses and horses with experimentally induced cardiac disease.

OBJECTIVE: To compare cardiac troponin I (cTnI) concentrations determined by use of a point-of-care analyzer with values determined by use of a bench-top immunoassay in plasma samples obtained from clinically normal horses with and without experimentally induced cardiac disease, and to establish a reference range for plasma equine cTnI concentration determined by use of the point-of-care analyzer. ANIMALS: 83 clinically normal horses, 6 of which were administered monensin to induce cardiac disease. PROCEDURES: A blood sample was collected from each of the 83 clinically normal horses to provide plasma for analysis by use of the point-of-care analyzer; some of the same samples were also analyzed by use of the immunoassay. All 83 samples were used to establish an analyzer-specific reference range for plasma cTnI concentration in clinically normal horses. In 6 horses, blood samples were also collected at various time points after administration of a single dose of monensin (1.0 to 1.5 mg/kg) via nasogastric intubation; plasma cTnI concentration in those samples was assessed by use of both methods. RESULTS: The analyzer-specific reference range for plasma cTnI concentration in clinically normal horses was 0.0 to 0.06 ng/mL. Following monensin treatment in 5 horses, increases in plasma cTnI concentration determined by use of the 2 methods were highly correlated (Pearson correlation, 0.83). Peak analyzer-determined plasma cTnI concentrations in monensin-treated horses ranged from 0.08 to 3.68 ng/mL. CONCLUSIONS AND CLINICAL RELEVANCE: In horses with and without experimentally induced cardiac disease, the point-of-care analyzer and bench-top immunoassay provided similar values of plasma cTnI concentration.

Blueberry fruit polyphenolics suppress oxidative stress-induced skeletal muscle cell damage in vitro.

Skeletal muscle damage can result from disease and unaccustomed or excessive exercise. Muscle dysfunction occurs via an increased level of reactive oxygen species and hence there is potential in antioxidants as amelioration strategies. We explored the putative benefit of fruit polyphenolic extracts in reducing the susceptibility of skeletal muscle cells to oxidative stress. Muscle myotubes were simultaneously challenged with fruit extracts (1-50 microg/mL) and calcium ionophore (A23187), hydrogen peroxide, or 2,4-dinitrophenol and damage monitored by release of cytosolic enzymes. A blueberry fruit extract displayed a potent and significant dose-dependent protective capacity. Evaluation of the protective capacity of anthocyanin sub-extracts of blueberry fruit and pure individual glycosides, with identification of extract polyphenolic components using MS, suggested that malvidin galactoside and/or glucoside were the active compounds. These in vitro data support the concept that blueberry fruits or derived foods rich in malvidin glycosides may be beneficial in alleviating muscle damage caused by oxidative stress. More research on the benefits of blueberry fruit consumption in human intervention studies is warranted.

Effects of organophosphate phenyl saligenin phosphate and polyether carboxylic ionophore lasalocid on motor nerve conduction velocity, neuropathy target esterase enzyme activity, and clinical ataxia in chickens.

Organophosphates (OP) are widely used chemicals in agriculture and industry. Some OPs produce a delayed type of neuropathy affecting human and animals following exposure. Subacute neurotoxic doses of some OPs can be potentiated by concomitant exposure to certain chemicals. Lasalocid is a polyether carboxylic ionophore used as a growth promotant and anti-coccidial in the cattle and poultry industries, respectively. Lasalocid is also known to induce peripheral neuropathy. Neurotoxicity of phenyl saligenin phosphate (PSP) and lasalocid and possible interaction were studied in chickens by evaluating motor nerve conduction velocity (MNCV), clinical ataxia, and neuropathy target esterase (NTE) enzyme activity. Forty-eight fryer chickens were divided into four groups as follows: Group 1 (control), group 2 was injected with single subcutaneous (s.c.) PSP (5 mg/kg), group 3 received oral lasalocid sodium (20 mg/kg, b.i.d., for 2 days), and group 4 received single s.c. PSP injection plus oral lasalocid sodium. MNCVs were decreased in groups 2, 3, and 4 compared to control. While there was no difference in MNCV between groups 2 and 3 (p > 0.05), MNCV in group 4 were significantly lower than in groups 2 and 3 (p < 0.05). NTE activities were significantly lower in PSP and PSP+lasalocid groups than in control and lasalocid group (p < 0.05). Onset of ataxia in group 4 appeared early and was exacerbated compared to groups 2 and 3. In conclusion, PSP and lasalocid could induce a significant decrease in MNCV and produce ataxia. Neuropathic OPs could be exacerbated by polyether ionophore lasalocid.

Accidental and experimental salinomycin poisoning in rabbits / Intoxicações natural e experimental por salinomicina em coelhos

An outbreak of salinomycin poisoning in rabbits is described. At least 27 out of 2,000 rabbits reared on a farm died after the coccidiostatic drug sulfaquinoxaline was substituted by salinomycin in the feed. An average of 26.9ppm salinomycin was detected in the ration given to the rabbits. Clinical signs included anorexia, apathy and bradykinesia, which progressed to incoordination and recumbency. Gross lesions consisted of pale areas in the skeletal muscles. The histopathological findings showed severe necrotic degenerative myopathy in association with infiltration of neutrophils and macrophages. One rabbit exhibited similar alterations in the myocardium. Mineralization was observed in the affected skeletal muscles in some cases. In order to verify if the poisoning was due to salinomycin, 20 rabbits were divided into five groups and a ration containing the drug at doses of 10, 25, 50, 75 and 100ppm was given. The administration of doses higher than 50ppm resulted in manifestation of the clinical signs seen in the outbreak of poisoning. It was concluded, that probably an error related to the mixture of salinomycin in the feed was the cause of deaths in the spontaneous outbreak of poisoning on the rabbit farm.

Relata-se, pela primeira vez, um surto de intoxicação por salinomicina em coelhos. De 2000 animais, no mínimo 27 morreram após troca do coccidiostático sulfaquinoxalina pela salinomicina. A análise de parte da ração detectou 26,9ppm de salinomicina. Os sinais clínicos observados foram anorexia, apatia e lentidão com evolução para incoordenação dos movimentos e decúbito. As lesões macroscópicas consistiram de áreas pálidas na musculatura esquelética. O exame histopatológico evidenciou miopatia degenerativo-necrótica. Adicionalmente, verificou-se reação inflamatória constituída por neutrófilos e macrófagos. Um coelho apresentou lesões similares no miocárdio. Em alguns casos, mineralização estava presente nos músculos esqueléticos afetados. Vinte coelhos experimentais foram divididos em 5 grupos que receberam 10, 25, 50, 75 e 100ppm de salinomicina por via oral, com a finalidade de reproduzir a intoxicação. Os animais que receberam a partir de 50ppm de salinomicina apresentaram sinais clínicos semelhantes aos observados no surto espontâneo. Nossos resultados indicam que, provavelmente, erro na mistura da substância à ração causou a morte dos coelhos.