Detection of synthetic glucocorticoid residues in cattle tissue and hair samples after a single dose administration using LC-MS/MS

A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the detection of several synthetic glucocorticoids in kidney, muscle and hair samples of cattle after a single intramuscular injection is described. After a dichloromethane wash of the hair samples, analytes were released from the hair matrix by enzymatic digestion. Muscle samples were also digested enzymatically using proteinase, while kidney samples were deconjugated by Helix pomatia juice. These preliminary steps were followed by a methanol extraction and a solid phase extraction (SPE) clean up step for all matrices. Chromatographic separation was achieved on a Hypersil Hypercarb column and MS/MS data were obtained in the multiple reaction monitoring mode using negative electrospray ionization. The developed protocols were evaluated by assessing residue concentrations in muscle, kidney and hair samples of thirteen calves, treated with a particular intramuscular injection of glucocorticoid. The lowest residue levels were found in muscle samples (approximately 5% of the residue levels in kidney), while high residue levels were obtained in hair samples. Hair is an interesting matrix since the sampling is non-invasive and the drugs may stay incorporated for a longer period of time. (C) 2004 Elsevier B.V. All rights reserved.

Comparison of the volatile components of eight cultivars of potato after microwave baking

Eight cultivars of potato were baked in a microwave oven. The flavour components of the flesh were isolated by headspace trapping onto Tenax and analysed by gas chromatography-mass spectrometry. Lipid degradation and the Maillard reaction and/or sugar degradation were the main sources of the 80 flavour components identified. It is suggested that total levels of compounds and variations among their profiles may be attributed to differences in activities of lipid enzymes and levels of flavour precursors in the range of cultivars investigated. (C) 2002 Elsevier Science Ltd.

The day after: effects of vocal interactions on territory defence in nightingales

Models on territory acquisition and tenure predict that territorial animals benefit by adjusting territorial defence behaviour to previous challenges they had experienced within the socially complex environment of communication networks.

Age-related differences in rapid muscle activation after rate of force development training of the elbow flexors

In young adults, improvements in the rate of force development as a result of resistance training are accompanied by increases in neural drive in the very initial phase of muscle activation. The purpose of this experiment was to determine if older adults also exhibit similar adaptations in response to rate of force development (RFD) training. Eight young (21-35 years) and eight older (60-79 years) adults were assessed during the production of maximum rapid contractions, before and after four weeks of progressive resistance training for the elbow flexors. Young and older adults exhibited significant increases (P<0.01) in peak RFD, of 25.6% and 28.6% respectively. For both groups the increase in RFD was accompanied by an increase in the root mean square (RMS) amplitude and in the rate of rise (RER) in the electromyogram (EMG) throughout the initial 100 ms of activation. For older adults, however, this training response was only apparent in the brachialis and brachioradialis muscles. This response was not observed in surface EMG recorded from the biceps brachii muscle during either RFD testing or throughout training, nor was it observed in the pronator teres muscle. The minimal adaptations observed for older adults in the bifunctional muscles biceps brachii and pronator teres are considered to indicate a compromise of the neural adaptations older adults might experience in response to resistance training.

Involvement of Nox2 NADPH oxidase in adverse cardiac remodeling after myocardial infarction.

Oxidative stress plays an important role in the development of cardiac remodeling after myocardial infarction (MI), but the sources of oxidative stress remain unclear. We investigated the role of Nox2-containing reduced nicotinamide-adenine dinucleotide phosphate oxidase in the development of cardiac remodeling after MI. Adult Nox2(-/-) and matched wild-type (WT) mice were subjected to coronary artery ligation and studied 4 weeks later. Infarct size after MI was similar in Nox2(-/-) and WT mice. Nox2(-/-) mice exhibited significantly less left ventricular (LV) cavity dilatation and dysfunction after MI than WT mice (eg, echocardiographic LV end-diastolic volume: 75.7+/-5.8 versus 112.4+/-12.3 microL; ejection fraction: 41.6+/-3.7 versus 32.9+/-3.2%; both P