The release of prostaglandins (PGs) and thromboxanes (Txs) from perfused guinea pig lungs was investigated during different immunological states. The major product released from normal lungs perfused with exogenous arachidonic acid was 6-oxo-PGF1α. The procedure of sensitisation to specific antigen resulted in an increase in the release of 15-oxo-13,14-dihydro-TxB2 and a decrease in the release of 6-oxo-PGF1α- and 6,15-dioxo-13,14-dihydro-PGF1α from lungs perfused with arachidonic acid. The relative amount of 15-oxo-13,14-dihydro-TxB2 released progressively increased with the number of immunological challenges with both exogenous and endogenously derived substrate, arachidonic acid. This change in response to successive immunological challenges may represent a protective mechanism to prevent parent Txs and PGs entering the systemic circulation.
A crude extract from an ergot fermentation broth has been examined by high-performance liquid chromatography mass spectrometry (LCIMS). The [Mcl]' ions formed from the mixture under chemical ionization conditions have also been studied using BIE linked scans with and without collision induced dissociation. Data obtained from high-performance liquid chromatography mass spectrometry have been used to identify 11 alkaloids in a mixture of at least 18 unknown molecules. BIE Linked scan spectra obtained with and without collision activated dissociation from pure samples proved useful in differentiating isomeric alkaloids and in providing stereochemical information. Problems were encountered in application of these latter techniques to studies of the crude extract; in particular in the identification of isomers and in the presence of peaks arising from fragment ions formed from higher mass alkaloids present in the mixture.
A prominent orfho interaction occurs during the maSs spectrai fragmentation of di(2-nitrophenyl)sulphides. No such effects are observed for the corresponding ethers or 2-(2-nitroaniiino)thiophens. Variation of aromatic substituents can dramatically alter the effect. Examination of anaiogous suiphone, sulphoxide, and disuiphide moledes, Snplicates the involvement of the ortho Níro substituent and the sulphw atom i0 this rearrangement.
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