[Malignant phyllodes tumour : a case report].

A 28 year old woman has suffered over the previous month from a post-traumatic swelling sensation of the left breast. Ultrasonography demonstrates a 9 cm, sharply-cut, rounded, hypo-echogenic lesion. Surgery is performed, with the hypothesis of an haematoma.

Tandem mass spectrometric characterization of a specific cysteic acid residue in oxidized human apoprotein B-100.

The oxidation of low density lipoprotein (LDL) in vivo may result in its unregulated uptake by macrophages, with the consequent accumulation of cholesterol that is characteristic of the development of atherosclerosis. This paper describes initial experiments to elucidate structural changes that occur in an in vitro model of LDL oxidation. LDL was isolated from human blood and oxidized in the presence of copper ion.

Determination of high-energy fragmentation of protonated peptides using a beqq hybrid mass spectrometer.

A hybrid tandem instrument of BEqQ geometry was used to determine high-energy decomposition of protonated peptides, such as side-chain fragmentation yielding d n and w n ions. The transmission through both E and Q of such product ions, formed in the second field-free region, permits improved mass resolution and confident mass assignment. The experimental technique may involve synchronous scanning of E and Q, or, for the purpose of identification of specific products, limited-range scanning of either E or Q with the other analyzer fixed.

Decompositions of cationized heterodimers of amino acids in relation to charge location in peptide ions.

The unimolecular decompositions of protonated heterodimers of native and derivatized amino acids to yield the protonated monomers were studied as a guide to charge location in peptide ions. Analyses using a hybrid instrument of BEqQ geometry demonstrated the advantages (with respect to mass resolution, sensitivityr reproducibility, and the elimination of extraneous signals) of the detection of product ions formed in the radiofrequency-only quadrupole region (q) rather than in the field-free region between Band E. Conversion of arginine to dimethylpyrimidylomithine (DMPO) reduced the proton affinity, as evidenced by the decomposition of the protonated arginine/DMPO heterodimer.