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Insulin-like growth factor-1 could be a useful marker in the horse for diagnostic, selection, or forensic purposes, provided its physiological regulation is well understood. The objective of this study was to investigate factors, such as acute exercise, fitness training, time of day, sex, and age, that may influence serum IGF-1 in normal, healthy horses. Throughout a 9-wk training program, 6 geldings maintained a mean (+/- SEM) IGF-1 concentration of 302 +/- 29 ng/mL. Moderate or high intensity exercise had no effect on IGF-1 concentrations, when pre- and postexercise values were compared. Over a 24-h period, there was some variation in IGF-1 concentrations but no clear diurnal rhythm. Concentrations of IGF-1 were measured in a large population of thoroughbred horses (1,880) on 3 continents. The population deviated slightly from a normal distribution (P < 0.001) because of large IGF-1 concentrations in 10 horses. The global mean IGF-1 concentration was 310 +/- 2.2 ng/mL, with a greater mean value (P < 0.001) in gonad-intact males (336 +/- 5.6 ng/mL) than in females (303 +/- 3.2 ng/mL) or geldings (302 +/- 3.2 ng/mL). However, the greatest IGF-1 concentrations observed for all stallions, mares, and geldings were 627, 676, and 709 ng/mL, respectively. In mares and geldings, IGF-1 concentrations showed a gradual decrease with advancing age (P < 0.001), but the effect was much less marked in stallions. This study confirms that IGF-1 concentrations are stable, compared with GH concentrations, in the horse and that a meaningful measure of IGF-1 status can be obtained from a daily serum sample.

Previous studies have shown that insulin-like growth factor 1 (IGF-1) is a promising marker for the detection of growth hormone (GH) abuse in the horse. The significant increases observed with GH administration in comparison to natural levels imply the possibility of setting a threshold level for IGF-1 that would be indicative of GH abuse. Although an immunoradiometric assay (IRMA) has been identified as a reliable screening method, a more specific IGF-1 quantification method needs to be developed for the prosecution of GH abuse by horseracing authorities. This study describes such an HPLC electrospray mass spectrometry (LC/ESI-MS) method that was developed and then assessed for the specific analysis of IGF-1 at the low levels encountered in serum. The structural identity of IGF-1 was confirmed by endoproteinase Asp-N digestion followed by LC/MS and LC/MS/MS characterisation. This was followed by quantification of IGF-1 as the intact molecule against an internal standard.

A mass spectrometric method for the analysis of aziridines and their 2-chloroethylamine precursors is described. These compounds are characterized by their highly labile interconvertible nature. The capabilities of electron impact and fast atom bombardment (FAB) mass spectrometry as ionizaton techniques for structure confirmation studies were explored. A new technique using FAB mass spectrometry to distinguish between an aziridine and its open-chain precursor is described. INTRODUCTIONDuring an investigation of contraceptive compounds occurring in the shrub Salsola tuberculatiformis Botsch., an active fraction (S2), showing a single symmetrical peak in different high-performance liquid chromatography (HPLC) systems, was isolated in microquantities.' This fraction proved to be highly sensitive to light, heat, alkaline pH and air. Autocatalytic degradation and polymerization occurred very rapidly if appropriate steps were not taken. Decomposition in acidic aqueous medium led to the formation of I-(4-hydroxyphenyl)-2-(methylamino)ethanol (I, Fig. I), also called synephrine. This paper describes the utilization of electron impact (ET) and fast atom b~m b a r d m e n t~,~ (FAB) mass spectrometric techniques for the chemical investigation of S2, a number of structurally related synthetic aziridines and their 2-chloroethylamine precursors.Acetylation of S2 yielded a derivative which, although still labile, showed a reduced tendency to decompose in In an attempt to gain insight into the composition and chemical properties of this active fraction (S2), a series of eight model compounds (IVa-d, Va-d, Fig. 2) was synthesized, purified and the structural integrity of each confirmed by nuclear magnetic resonance (NMR). Compounds IVa and IVb were synthesized from l-phenyl-2-aminoethanol and l-phenyl-2-(methylamino)ethanol according to the method of AppeL7 Treatment of 1-phenyl-2-aminoethanol and l-phenyl-2-(methylamino)-ethanol in chloroform with gaseous hydrochloric acid yielded compounds Va and Vb. Compounds Vc and Vd were obtained from octopamine and synephrine by Mass spectra were recorded on a VG70-70E mass spectrometer equipped with a VG2035 data system. All samples were run under positive ion operating conditions. EI operating conditions were as follows: electron energy 70 eV; filament emission current, 100 FA; source temperature, varied between 80 and 200 OC; acceleration voltage, 4 kV. The magnetic analyser was scanned at a rate of 2 s per decade in the mass range 400-30 Da. Samples were introduced into the ion source using the standard VG heated direct-insertion probe.FAB mass spectra were recorded with an Ion Tech saddle-field gun' employing xenon9 as bombardment gas (8 kV, 1 mA). The mass spectrometer was operated at 6 kV and the magnetic analyser was scanned at a rate of 5 s per decade over the range 500-100 Da. Glycerol," obtained from Fluka, was employed as a matrix, however; 3-nitrobenzylalcohol" proved to be equally suitable. RESULTS A N D DISCUSSIONThe EI and FAB results of this study are summarized in Table ...

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