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  • Author: Anna Gajda x
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Abstract

A liquid chromatography – tandem mass spectrometry (LC-MS/MS) method for the determination of oxytetracycline (OTC), 4-epi oxytetracycline (4-epi OTC), tetracycline (TC), 4-epi tetracycline (4-epi TC), chlortetracycline (CTC), 4-epi chlortetracycline (4-epi CTC), doxycycline (DC), minocycline (MINO), methacycline (META) and rolitetracycline (ROLI) residues in muscles was developed. The procedure consisted of an oxalic acid extraction followed by protein removal with trichloroacetic acid. Further solid phase clean-up on polymeric (Strata X) reversed phase columns was performed to obtain an extract suitable for LC-MS/MS analysis. The tetracyclines were separated on a C 18 analytical column with mobile phase consisting of 0.01% formic acid in acetonitrile and 0.01% formic acid in water in gradient mode. The method was validated according to the Commission Decision 2002/657/EC. The recoveries of all target compounds were 91.8% – 103.6%. The decision limits were from 109.0 to 119.8 μg/kg and detection capability varied within the range of 122.2 to 137.6 μg/kg, depending on the analyte.

Abstract

For the purpose of quantitative determination of doxycycline (DC) residues in tissues, a sensitive liquid chromatography - tandem mass spectrometry (LC-MS/MS) method was developed. The method was used to determine DC residues in chicken tissues (breast and thigh muscle, liver and kidney) after oral administration with drinking water to five-weak-old broiler chickens. The DC was administered for five consecutive days at a therapeutic dose of 10 mg/kg b.w. once a day. The tissues were collected after 6 h, 24 h, 7 d, and 8 d. The method was validated and the decision limit was established for muscle - 109.2 μg/kg, for liver - 326.1 μg/kg, and for kidney - 634.0 μg/kg. The detection limit was 2 μg/kg and the limit of quantification was 5 μg/kg. In a short period after ceasing the treatment, the detected concentrations of DC were much higher than the established maximum residue limit values. The highest residue concentrations of DC were observed in the kidney, followed by the liver and muscle. The lowest concentration of DC was determined in tight muscle.

Abstract

For the measurement of tulathromycin distribution in swine plasma an accurate and reliable analytical method was developed. The extraction was performed with oxalic acid buffer (pH=4.0). Plasma samples were cleaned up by solid phase extraction procedure using polymeric cartriges. Chromatographic separation was achieved on a C 18 analytical column using mobile phase consisting of acetonitrile, 0.1% formic acid in gradient mode. Detection was carried out by liquid chromatography tandem mass spectrometry. Azithromycin was used as internal standard. The method has been successfully validated. The recovery from spiked samples ranged from 94% to 110%. The limit of detection was 2 ng/mL and the limit of quantification was 5 ng/mL. The method was developed to investigate the pharmacokinetics of tulathromycin in swine plasma. Applicability of the method was tested with plasma from swine administered with a single dose of tulathromycin.

Summary

A liquid chromatography method with UV detection for determination of oxytetracycline (OTC) in honey has been developed. The samples were extracted with the solution of oxalic acid. The clean-up procedure was performed by solid phase extraction (SPE) using polymeric Strata X and carboxylic acid cartridges. Chromatographic separation was carried out on the Luna C8 analytical column with mobile phase consisting of acetonitrile-0.02 M oxalic acid. The method has been successfully validated according to the requirements of the European Decision 2002/657/EC and this method is used in routine control of oxytetracycline in honey samples. The limit of detection (LOD) and limit of quantification (LOQ) of the presented method were 10 and 12.5 μg/kg, respectively. The developed method has also been verified in quantitative determination of oxytetracycline residues in honey after experimental treatment with this product in bee colonies.

Summary

Estimations of honeybee colony winter losses in Poland have been carried out at Warsaw University of Life Sciences since 2008 (in 2008 they concerned the two winters of 2006/07 and 2007/08), using a preliminary questionnaire in 2008 and the standardized COLOSS questionnaire since 2009. During the first years of the survey, concerning the period of autumn 2006 - spring 2012, the multimode method of data collection was used, and beekeepers sent in between 393 and 769 questionnaires a year. Overall, the number of participants increased, but in particular voivodeships it fluctuated. The estimated overall winter colony loss in Poland was low during the winter of 2006/07 (10%) and quite low during the winter of 2008/09 (11.5%). In other years it was substantially higher reaching 15.2% in 2007/08, 14.8% 2009/10, as much as 18.3% in 2010/11 and then down to 15.8% in 2011/12. A similar pattern of average losses was observed, but each year, excluding the winter of 2010/11, at least 50% of beekeepers reported acceptable losses of only up to 10%. During the analysis of the spatial pattern of overall losses, some data which could blur the pattern were eliminated. The results suggest that such climatic factors as a warm autumn but also high summer precipitation, followed by low winter temperatures influenced the spatial distribution of the losses.

Abstract

Termin gammapatia monoklonalna o znaczeniu nerkowym (MGRS) w akronimie różni się jedynie jedną literą od gammapatii monoklonalnej o nieokreślonym znaczeniu (MGUS), jednakże w znaczeniu klinicznym jest to zupełnie inna jednostka. W przebiegu MGRS białko produkowane przez klon komórek uszkadza nerki, przez co może prowadzić do ich niewydolności. W niniejszym artykule dokonano przeglądu piśmiennictwa dotyczącego jednostek chorobowych zaliczanych do grupy MGRS, ich podziału ze względu na typ uszkodzenia nerek i charakterystykę deponowanych w nich złogów. W pracy omówiono także współczesne możliwości leczenia w poszczególnych jednostkach chorobowych zaliczanych do MGRS.

Abstract

Introduction: Quercetin is a polyphenolic flavonoid which has been used in traditional Chinese medicine as a natural therapeutic agent with a broad spectrum of activities (antioxidant, anticancer, neuroprotective, anti-inflammatory, antiviral and antibacterial). The aim of this study was to develop and validate a rapid and simple ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) method for the determination of quercetin in milk.

Material and Methods: Sample preparation was based on a liquid-liquid extraction with 0.5% formic acid in acetonitrile. The chromatographic separation was performed on a ZORBAX SB-C18 column with methanol and 0.5% formic acid as a mobile phase.

Results: The procedure was successfully validated. The mean recovery of the analyte was 98%, with the corresponding intra- and inter-day variation less than 10% and 15%, respectively, and the repeatability and reproducibility were in the range of 3%–7.2% and 6.1%–12%, respectively. The lowest level of quantification was 1.0 μg/kg.

Conclusion: The proposed method was successfully applied in evaluating the pharmacokinetics of quercetin in milk obtained from dairy cows with clinical mastitis after intramammary administration.

Abstract

Introduction: There are many veterinary products containing β-lactam antibiotics which are used for mastitis treatment in cows. The aim of the study was to determine whether mastitis could have any effect on amoxicillin (AMX) or penicillin G procaine (PEN) withdrawal period from milk, in the context of current maximum residue limits established by the European Commission.

Material and Methods: The study was conducted on 17 dairy Black and White cows with clinical mastitis during the lactation period. The first group (n = 8) received 200 mg of amoxicillin (AMX), whereas the second group (n = 9) received 200,000 IU/mg of penicillin G procaine (PEN) by intramammary administration. For the measurement of AMX and PEN concentrations in milk, the liquid chromatography tandem mass spectrometry method was applied. Pharmacokinetic calculations were performed using Phoenix WinNonlin 6.4 software.

Results: The determined AMX and PEN half-life values in the mammary gland suggest that the drug withdrawal is at a level of 99.9% within 81 h (≈3.5 days) and 116 h (≈5 days) after administration of AMX and PEN, respectively. The present research indicates that, at 60 h after administration, the average PEN concentration in the milk from cows with clinical signs of mastitis may still reach 4.96 g/kg and that of AMX can even be 6.92 g/kg.

Conclusion: The results obtained confirm that, in mastitis cases, a 72-h withdrawal period is sufficient for elimination of AMX to a lower level than the established maximum residue limit (MRL) values. However, in the case of PEN, at 69 h after administration, the drug concentration may be close to that of the determined MRL.

Individual Susceptibility to Noise-Induced Hearing Loss: Choosing an Optimal Method of Retrospective Classification of Workers into Noise-Susceptible and Noise-Resistant Groups

Objectives: Individual susceptibility to noise-induced hearing loss (NIHL) depends on the interaction between intrinsic and environmental factors. To proceed with the study on NIHL susceptibility genes an appropriate selection of workers susceptible and resistant to noise is crucial. The aim of the study was to compare four different methods of subject classification by the susceptibility to NIHL in a group of 949 workers of an electric power plant exposed to steady-state noise at the workplace. Materials and Methods: One method based the classification of the workers on the international reference standard ISO 1999:1990; from the entire group of workers, 10% of the subjects with the worst hearing thresholds (HT) in the model were categorized as susceptible to NIHL, whereas 10% of the subjects with the best HT were categorized as resistant to noise. According to three other methods, the entire group of workers was first divided into subgroups by age, duration of employment and the level of noise, and then 10% of the subjects at each HT extreme were selected. Results: The first classification allowed to achieve an excellent separation between HT of the susceptible and resistant subgroups. The susceptible subgroup was significantly younger than the resistant one, showed a shorter duration of employment and a lower level of noise exposure, which is in line with the definition of increased vulnerability to NIHL. The three other methods produced poorer separation of HT with smaller or no gap between HT values in subgroups. Conclusions: The selection of subjects from the entire worker population of a given industry based on the ISO 1999:1990 standard can be regarded as the most reliable method of classification of noise-susceptible and noise-resistant workers to be used in the future genetic studies on NIHL susceptibility genes.

Abstract

A liquid chromatographic method coupled with tandem mass spectrometry for determination of residues of β-lactams, macrolides, tetracyclines, quinolones, sulfonamides, and lincosamides in eggs has been described. Analytes were isolated from egg samples by solvent extraction method and extracts were cleaned by filtration on OASIS HLB cartridges. The whole procedure was validated according to European Commission Decision 2002/657/EC. The recovery ranged between 86% and 110%. The repeatability was below 16% and within-laboratory reproducibility was lower than 20%. The method was successfully applied in the official control of antibacterial compounds residue in Poland.