Food-borne clenbuterol may have potential for cardiovascular effects with chronic exposure (commentary)

Development of a highly sensitive and specific monoclonal antibody based enzyme-linked immunosorbent assay for the detection of a new β-agonist, phenylethanolamine A, in food samples

BACKGROUND

All β-agonists are banned as feed additives for growth promotion in animals due to toxic effects on humans after consuming the β-agonist contaminated meats. Phenylethanolamine A (PA) is a newly emerged β-agonist. Thus there is a need to develop highly sensitive and specific analytical methods for the detection of PA in food samples. In this study, the monoclonal antibody (mAb) against PA was produced by hybridoma technology and used for the development of enzyme-linked immunosorbent assay (ELISA).

RESULTS

The IC₅₀ values and limits of detection (LODs) of the ELISA using homogeneous combination of coating antigen/antibody for PA were 0.16 ng mL^-1 and 0.011 ng mL^-1 , respectively. The cross-reactive (CR) values of the assay with 14 structurally related β-agonists were lower than 0.59%. Swine liver and meat samples were spiked with PA at different content and analysed by ELISA. Acceptable recovery rates of 91.40-105.51% and intra-assay coefficients of variation of 1.56-9.92% (n = 3) were obtained. The ELISA for seven spiked samples was confirmed by LC-MS/MS with a high correlation coefficient of 0.9881.

CONCLUSION

The proposed mAb-based ELISA was highly sensitive and specific for PA and could be used as a quantitative/screening method for PA analysis in food samples. © 2016 Society of Chemical Industry.

Case of low dose clenbuterol toxicity

We present a case of acute clenbuterol toxicity following ingestion of 20 μg of clenbuterol, resulting in symptoms of sympathetic activation, sinus tachycardia and electrolyte derangement. The patient was managed conservatively with fluid resuscitation, electrolyte replacement and monitoring, and discharged following a 5-day stay in hospital.

A quantum dot based electrochemiluminescent immunosensor for the detection of pg level phenylethanolamine A using gold nanoparticles as substrates and electron transfer accelerators

This study reports the development of an electrochemiluminescent (ECL) immunosensor for ultrasensitive detection of phenylethanolamine A (PA) based on CdSe quantum dots (QDs) and gold nanoparticles (GNPs). The GNPs/ovalbumin-PA/anti-PA-QD immunosensor was fabricated layer by layer using GNPs as substrates and electron transport accelerators. The use of GNPs greatly enhanced the sensitivity for detecting PA due to the excellent electron transportation ability and the large surface area of GNP carriers allowing several binding events of ovalbumin-PA on each nanosphere. Transmission electron microscopy images (TEM), photoluminescence spectra, ultraviolet-visible absorption spectra and dynamic light scattering (DLS) were used to characterize the QDs and GNPs. The sensor was characterized with electrochemical impedance spectra (EIS), and a strong ECL emission of the modified electrode could be observed during the cathodic process of S2O8(2-) and QDs in air-saturated PBS buffer containing 0.1 M K2S2O8 and 0.1 M KCl (pH 7.4). With a competitive immunoassay format, the ECL signal depended linearly on the logarithm of the phenylethanolamine A concentration within a range of 0.02 ng mL(-1) to 50 ng mL(-1), and the detection limit was 0.0047 ng mL(-1), much lower than those reported in the literature. This ECL immunosensor is rapid, simple and sensitive with acceptable precision, and it will extend the application of QD ECL in immunoassays of β-agonists and open new avenues for the detection of food additive residues in the future.

Ultrasensitive and quantitative detection of a new β-agonist phenylethanolamine A by a novel immunochromatographic assay based on surface-enhanced Raman scattering (SERS)

Phenylethanolamine A (PA) is a new kind of β-agonist, which was illegally used as a feed additive for growth promotion in China. In this study, a novel immunochromatographic assay (ICA) based on surface-enhanced Raman scattering (SERS) for the ultrasensitive and quantitative detection of phenylethanolamine A is presented. The principle of this new ICA is similar to that based on colloidal gold particles, but using Au(MBA)@Ag-Ab [e.g., polyclonal antibody of PA labeled Au@Ag core-shell nanoparticles (NPs) sandwiched with a Raman reporter (4-mercaptobenzoic acid, MBA)] as a probe. After ICA procedures, the specific Raman scattering intensity of MBA on the test line was measured for quantitative detection of PA. This assay was completed within 15 min. The IC50 and limit of detection (LOD) values of the ICA for PA detection were 0.06 ng mL(-1) and 0.32 pg mL(-1), respectively, which were 1-3 orders of magnitude lower than those obtained by other immunoassays, indicating the ultrasensitivity of this ICA. There was no cross-reactivity (CR) of the assay with another three β-agonists (ractopamine, clenbuterol, and salbutamol), suggesting high specificity of the SERS-based ICA. A spiking experiment revealed that the recoveries of PA from pig urine samples were in range of 99.9- 101.2% with relative standard deviations (RSDs) of 3.6-5.8%. The results demonstrated that this SERS-based ICA was able to quantitatively detect PA in urine samples with high sensitivity, specificity, precision, and accuracy and might be a powerful method for the analysis of other target analytes in the food area.

Hair analysis, a reliable and non-invasive method to evaluate the contamination by clenbuterol

The illegal use of clenbuterol has been an increasingly serious issue in today's livestock products industry. It becomes an important project to develop a reliable approach to detect its content in food animals. A simple and sensitive LC-MS/MS method was developed to detect clenbuterol residue in hair, with the low limit of quantitation (LLOQ) about 0.5ng/g. Hogs fed with 340µg/day of clenbuterol for 2 weeks were found a high clenbuterol residue in their hair approximately at 1-2 months after withdrawal. There remained 3.31ng/g clenbuterol in hog hair approximately 5 months after the last administration, focused on the tip of the hair (mainly in hogs with dark hair). An extensive contamination was observed in twenty investigated market hogs whose dark hair obviously had a higher clenbuterol residue than the light ones (p=0.017, t test). Volunteers (60.3 percent) from Xuhui district (Shanghai) were found to have a detectable amount of clenbuterol in their hair (>0.5ng/g). In conclusion, hair residue detection is a reliable method to evaluate the clenbuterol contamination in animals and humans. Meat supply in the Xuhui district might have serious potential safety risks which should be further investigated and discussed to determine the safety range of clenbuterol residue.

A novel CdSe/CdS quantum dot-based competitive fluoroimmunoassay for the detection of clenbuterol residue in pig urine using magnetic core/shell Fe3O4/Au nanoparticles as a solid carrier

Quantum dots (QDs) are semiconductor fluorescent nanoparticles, which can be used for food safety or environmental monitoring with high sensitivity. This work demonstrates the feasibility of detecting clenuterol residue in pig urine using CdSe/CdS quantum dots as fluorescent labels based magnetic core/shell Fe3O4/Au nanoparticles (MCFN) as solid carriers. The detection of clenbuterol is carried out by a fluoroimmunoassay-based biosensor using competitive binding between conjugated clenbuterol antigen-CdSe/CdS QDs and free clenbuterol with immobilized clenbuterol antibodies on MCFN. This assay method allows for clenbuterol determination in a linear working range of 0.5-20000 pg mL(-1). It would provide a simple, rapid, and ultra-sensitive detection method for clenbuterol or other biomolecular analysis.

Acute clenbuterol overdose resulting in supraventricular tachycardia and atrial fibrillation

OBJECTIVE

We are presenting a case illustrating the complex metabolic and rhythm disturbances associated with acute clenbuterol intoxication.

BACKGROUND

Clenbuterol is a long-acting beta2-adrenergic agonist primarily used in veterinary medicine in the United States. It has become a common drug of abuse by body builders because of its reported anabolic and lipolytic properties. In this case report, a body builder using veterinary clenbuterol developed significant electrolyte and cardiac manifestations.

CASE REPORT

A 31-year-old man presented to the emergency department approximately 30 minutes after ingesting 1.5 ml (a tenfold dosing error) of Ventipulmin syrup (72.5 mcg/ml clenbuterol HCl). The product was brought to the emergency department (ED) by the patient. He reported no current use of anabolic steroids. He presented in an anxious state with complaints of palpitations and shortness of breath. Vital signs upon examination were as follows: BP, 122/77 mmHg (16.3/10.3 kPa); HR 254 bpm; RR, 22 bpm; Temperature, 97.1 degrees F (36 degrees C); and oxygen saturation, 100% on ambient air. His electrocardiogram (ECG) demonstrated supraventricular tachycardia with a ventricular rate of 254 bpm. Esmolol was recommended for rate control after the unsuccessful use of adenosine and diltiazem. Laboratory studies showed potassium, 2.1 mmol/L; magnesium, 1.3 mg/dL (0.54 mmol/L); phosphorus, 1.0 mg/dL (0.32 mmol/L); serum glucose, 209 mg/dL (11.6 mmol/L); creatinine, 0.8 mg/dL (70.7 micromol/L); AST, 20 U/L; ALT, 55 U/L; hemoglobin, 12.6 g/dL (126 g/L); CPK total, 87 U/L; and troponin I, 0.23 mug/L. The patient's urine was negative for any drugs of abuse. Clenbuterol levels were not obtained. A second ECG, 16 hours post ingestion, reflected atrial fibrillation with a ventricular rate of 125 to 147 bpm. On hospital day 3, he was electively cardioverted to sinus rhythm; heart rate and rhythm returned to normal, and he was discharged with oral metoprolol.

DISCUSSION

Clenbuterol is approved for use in countries outside the U.S. as a bronchodilator for the treatment of acute asthma exacerbations in humans. Although clenbuterol is not a steroid hormone, it possesses anabolic properties that increase muscle mass. Its longer duration of action compared to other beta2-agonists (such as albuterol) make it a desired agent for body-building because of its high and prolonged serum level. The mechanism for the short and long-term cardiovascular complications of clenbuterol is complex. The anabolic effects of clenbuterol are associated with its beta2-adrenoreceptor agonist activity on striated skeletal muscles. In addition, clenbuterol promotes lipolysis through adipocyte beta3-adrenoreceptors.

CONCLUSION

Considering the significant number of body-building enthusiasts, physicians will continue to encounter clenbuterol abuse in their clinical practices.

Solid-phase micro extraction (SPME) and headspace derivatization of clenbuterol followed by GC-FID and GC-SIMMS quantification

Solid-phase micro extraction (SPME) and on-fiber derivatization followed by Gas Chromatography coupled with Flame Ionization Detection (GC-FID) or Selected Ion Monitoring Mass Spectrometry (GC-SIMMS) allows for simple yet sensitive quantification for the hexamethyldisilazane derivative of the beta-agonist clenbuterol. Using an 85- micro m polyacrylate fiber, the analysis method is optimized with respect to extraction time, derivatization time and temperature, and solution pH. In addition, the use of a rapid temperature ramping injection port allows for optimization of fiber desorption conditions. Under optimal conditions, the limits of detection for the hexamethyldisilazane derivative of clenbuterol are 1.1 ppb by FID and 0.20 ppb by SIMMS.