Identification of the related substances of tilmicosin by liquid chromatography/ion trap mass spectrometry.

Rapid Commun Mass Spectrom. 2008 May 19;22(12):1993-1998

Authors: Stoev G, Nazarov V

Structures of seven impurities of the veterinary drug tilmicosin have been elucidated by multiple fragmentation with ion trap tandem mass spectrometry. All related compounds possess the main lactone ring of tilmicosin. The differences in their structures are due to the hydroxyl, mycaminose, 3,5-dimethylpiperidine and mycinose groups connected to C(3), C(5), C(6), C(14) of the lactone ring, respectively. The following compounds of the impurity profile of tilmicosin were identified: B - tilmicosin with a hydroxyl group at C(3); C - tilmicosin without a methyl group at the N-atom connected to C(3) of the mycaminose ring; D - tilmicosin with a hydroxyl group at C(6) of the mycaminose ring; E - tilmicosin with a methoxy group at C(3), F - desmicosin; G - 20-dihydrodesmicosin; and H - tilmicosin without a mycaminose ring. Isomers of the compounds B, C, D, E and H were identified by their mass chromatograms and retention times. The concentrations of the impurities varied in the range of 0.1% to 2.9%. Copyright (c) 2008 John Wiley & Sons, Ltd.

PMID: 18491285 [PubMed - as supplied by publisher]

Comprehensive screening and quantification of veterinary drugs in milk using UPLC-ToF-MS.

Anal Bioanal Chem. 2008 May 20;

Authors: Stolker AA, Rutgers P, Oosterink E, Lasaroms JJ, Peters RJ, van Rhijn JA, Nielen MW

Ultra-performance liquid chromatography combined with time-of-flight mass spectrometry (UPLC-ToF-MS) has been used for screening and quantification of more than 100 veterinary drugs in milk. The veterinary drugs represent different classes including benzimidazoles, macrolides, penicillins, quinolones, sulphonamides, pyrimidines, tetracylines, nitroimidazoles, tranquillizers, ionophores, amphenicols and non-steroidal anti-inflammatory agents (NSAIDs). After protein precipitation, centrifugation and solid-phase extraction (SPE), the extracts were analysed by UPLC-ToF-MS. From the acquired full scan data the drug-specific ions were extracted for construction of the chromatograms and evaluation of the results. The analytical method was validated according to the EU guidelines (2002/657/EC) for a quantitative screening method. At the concentration level of interest (MRL level) the results for repeatability (%RSD < 20% for 86% of the compounds), reproducibility (%RSD < 40% for 96% of the compounds) and the accuracy (80-120% for 88% of the compounds) were satisfactory. Evaluation of the CCbeta values and the linearity results demonstrates that the developed method shows adequate sensitivity and linearity to provide quantitative results. Furthermore, the method is accurate enough to differentiate between suspected and negative samples or drug concentrations below or above the MRL. A set of 100 samples of raw milk were screened for residues. No suspected (positive) results were obtained except for the included blind reference sample containing sulphamethazine (88 mug/l) that tested positive for this compound. UPLC-ToF-MS combines high resolution for both LC and MS with high mass accuracy which is very powerful for the multi-compound analysis of veterinary drugs. The technique seems to be powerful enough for the analysis of not only veterinary drugs but also organic contaminants like pesticides, mycotoxins and plant toxins in one single method.

PMID: 18491081 [PubMed - as supplied by publisher]

Biol Trace Elem Res. 2008 May 20;

Authors: Mert H, Mert N, Dogan I, Cellat M, Yasar S

The serum levels of copper, zinc, iron, manganese, nickel, cadmium, cobalt, sodium, potassium, calcium, and magnesium were determined in seven different breeds of dogs: Pointer, Poodle, Setter, Labrador Retriever, Golden Retriever, German Shepherd, and Mallinois. Only slight variations were found among the different breeds, and the results presented in this study can be used for laboratory studies in veterinary science.

PMID: 18491036 [PubMed - as supplied by publisher]

Prevalence of the Myosin-Binding Protein C Mutation in Maine Coon Cats.

J Vet Intern Med. 2008 May 21;

Authors: Fries R, Heaney AM, Meurs KM

Background: An autosomal dominant mutation has been identified in the myosin-binding protein C (MYBPC3) gene of Maine Coon cats. This mutation changes a conserved amino acid and computationally alters the protein conformation of this gene in Maine Coon cats with hypertrophic cardiomyopathy. The prevalence of this mutation is unknown. Objective: To determine the genetic prevalence of the MYBPC3 mutation in a large cohort of predominantly Maine Coon cats. Animals: Three thousand three hundred and ten DNA samples (blood or buccal swab) from cats. Methods: This retrospective study reviewed the Veterinary Cardiac Genetics Laboratory database at Washington State University for samples submitted for evaluation of the Maine Coon MYBPC3 mutation. The data were analyzed with respect to the breed of cat, mutation status (negative, heterozygous, homozygous), and geographic origin of the submission. Results: In the population of cats studied, Maine Coon cats accounted for 100% of all cats positive for the mutation, and the worldwide percentage of Maine Coon cats carrying the MYBPC3 mutation was 34%. Conclusions and Clinical Importance: The prevalence of the mutation (heterozygous or homozygous) was very similar among countries of submission, suggesting that the 34% mutation rate of the tested samples is a reasonable estimate of the true prevalence of the mutation within the breed. Because of the high prevalence of this mutation, a breeding recommendation to eliminate all cats with the mutation could have a substantial impact on the gene pool. Additional studies are indicated to explore the relationship between genotype and clinical outcome in affected cats.

PMID: 18498321 [PubMed - as supplied by publisher]