The PRIMA study: presentation ischaemia-modified albumin in the emergency department.

OBJECTIVES: To investigate the diagnostic accuracy of presentation ischaemia-modified albumin (IMA), in addition to cardiac troponin I (TnI), as a strategy to rapidly ascribe low risk to patients with chest pain attending an emergency department, and to determine whether IMA has the potential to reduce transit time in emergency departments. METHODS: A prospective observational study was carried out in two emergency departments (belonging to the John Radcliffe Hospital, Oxford, UK; and the Frenchay Hospital, Bristol, UK) of similar size. Consecutive adult patients presenting with features of possible ischaemic cardiac chest pain and a normal electrocardiogram were eligible. The index test (measurement of IMA and TnI at presentation) and reference standard (delayed TnI measurement, taken at least 8 h after pain onset) were applied to all recruited patients. All clinicians were blinded to the results of the index test. Assays were carried out in a single laboratory using standard techniques. RESULTS: 399 patients were recruited; 277 patients had a result for both the index test and reference standard. The sensitivity was 97.6% (95% confidence interval (CI) 87.4 to 99.9), negative predictive value 97% (95% CI 84.2 to 99.9) and specificity 13.6% (95% CI 9.5 to 18.7). Sensitivity analysis showed similar findings in three alternative scenarios. Receiver operating characteristic analysis indicated that a different "cut-off" value for IMA would not improve the properties of the test. The median potential time saved (n = 268) was 6 h and 10 min. CONCLUSION: The diagnostic accuracy of presentation IMA in this study does not support its use as an effective risk stratification tool for patients with chest pain in the emergency department. The sensitivity is insufficiently high, with a small number of false negatives undermining the safety of the test. Frequent false positives produce a low specificity that limits the practical value of the test.

Partial characterization of an antheridiogen of Anemia mexicana: Comparison with the antheridiogen of A. phyllitidis.

An antheridiogen of Anemia mexicana Klotzsch has been partially characterized by combined gas chromatography-mass spectrometry and gas chromatography-Fourier transform/infra-red spectrometry. It is a C19-gibberellin(GA)-like compound with one carboxyl group, an exocyclic methylene group and a lactone ring. It also has one hydroxyl-group and one double-bond equivalent which has not been determined. On the basis of its mass spectrum, it is not identical to previously identified monohydroxy GAs with one ring double bond such as GA5, GA7, GA31 and GA62. By direct comparison of mass spectra, the antheridiogen of A. mexicana was also determined to be different from the antheridiogens of Anemia phyllitidis (L.) Swartz, Anemia hirsuta (L.) Swartz and Lygodium japonicum (Thunb.) Sw.

Analysis of retinol and dideuterated retinol in rat plasma by gas chromatography combined mass spectrometry.

An isotope dilution method for determining the total body stores of vitamin A using a hydrocarbon derivative of rat plasma retinol, anhydroretinol (ANR) or dideuteroanhydroretinol (2H2ANR) has been evaluated by gas chromatography combined mass spectrometry (GC/MS). Rats with negligible vitamin A stores were dosed with retinyl acetate (ROA) or ROA and 11,12dideuteroretinyl acetate (2H2ROA). The 2H2ROA dose was allowed to equilibrate with total body stores for seven days and the deuterium/hydrogen ratio (D/H ratio) of rat plasma retinol fraction was determined. The results indicate that after the equilibration period the plasma D/H ratio is 73 to 108 percent of the loading dose D/H ratio. This study extends earlier reports that exogenous vitamin A storage is lower than the expected fifty percent figure in rats with low initial total body stores of vitamin A [1, 7, 8, 15, 17]. This work supports the concept that the estimation of total body stores of vitamin A by an isotope dilution method is useful for populations with negligible stores (i.e. liver stores) of vitamin A.

Analysis of deuterated analogs of vitamin A by electron impact and chemical ionization modes in gas chromatography coupled to mass spectrometry.

To evaluate the total body reserves of vitamin A in humans, deuterated forms of vitamin A are potentially useful probes. In the present investigation, we have selected anhydroretinol as a useful indicator of retinol isolated from plasma during GC/MS analysis because of its relatively high volatility, its formation from retinol in good yield directly on GC columns, and the improbability of deuterium loss or exchange during its formation. The major drawback in its use is the extensive isomerization to cis-isomers which occurred on GC columns even under mild conditions of analysis. Favorable conditions for the GC/MS assay of anhydroretinol in the EI mode were defined. The mass spectral response is linear with the amount of retinol injected from 10 to 400 ng, and the observed sensitivity is adequate for the measurement of retinol in 1 ml of plasma. By using isobutane or methane, chemical ionization mass spectra of anhydroretinol and retinaldehyde are reported for the first time. Although both gave the expected [M + H]+ molecular ion, analysis of anhydroretinol in the EI mode was a more appropriate and sensitive measure of retinol under our assay conditions.