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El feocromocitoma es un tumor neuroendocrino responsable del 0,05-0,1 por ciento de las hipertensiones secundarias, asociándose en ocasiones con normotensión. La miocardiopatía es una complicación rara, inducida por el exceso de catecolaminas. Presentamos el caso de una mujer joven que inició con cuadro de edema agudo de pulmón no cardiogénico sin hipertensión arterial asociada, debido a una miocardiopatía hipertrófica obstructiva grave. La paciente presentaba niveles elevados de catecolaminas y un tumor localizado en la glándula suprarrenal derecha. Después del comienzo del tratamiento alfa-beta bloqueante, se observó mejoría clínica y ecocardiográfica de la miocardiopatía, y la normalización posterior de los diámetros ventriculares tras la extirpación del feocromocitoma (AU)

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Atandem reflectron time-of-flight mass spectrometer developed in our laboratory provides a unique opportunity to investigate the collision-induced dissociation of fullerene ions formed by matrix-assisted laser desorption/ionization (MALDI). Specifically, this opportunity arises from the ability to utilize high energy collisional activation (normally available only on tandem sector instruments by using continuous ionization techniques) for ions formed by pulsed laser desorption, whereas most MALDI time-of-flight instruments record product ion mass spectra of ions formed by metastable or postsource decay. In this study we investigate the products of mass-selected and collisionally activated C 60 (+) and C 70 (+) ions by using different target gases over a range of target gas pressures. In general, heavier target gases produce more extensive fragmentation and improve the mass resolution of lower mass ionic products because a greater portion of these ions are formed by single collisions. Additionally, the tandem time-of-flight instrument utilizes a nonlinear (curved-field) reflectron in the second mass analyzer that enables high energy collision-induced dissociation spectra to be recorded without scanning or stepping the reflectron voltage.

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Electroblotting proteins separated by gel electrophoresis provides a suitable support for further manipulations and analysis of small amounts of relatively pure samples. On-membrane digestion, peptide mapping by mass spectrometry, and database searching offer sensitive and fast tools to identify the analyte. By providing sequence information, tandem mass spectrometry can go a step further, confirming the database identification, solving problems connected with post-translational modifications and sequence variations, or supplying the stretches of internal sequence necessary to synthesize an oligonucleotide probe for gene isolation. The viability of this approach was successfully evaluated using different tandem mass spectrometric techniques: metastable decomposition in a matrix-assisted laser desorption/ionization (MALDI) time-of-flight instrument with a curved-field reflectron; low energy collision-induced dissociation in a MALDI quadrupole ion trap mass spectrometer; and high energy collision-induced dissociation in a high-performance four-sector mass spectrometer with massive cluster-impact ionization.

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A time-of-flight mass spectrometer has been developed using a reflectron in which the voltages placed on the lens elements correspond to a function describing the arc of a circle. This curved-field reflectron enables acquisition of focused product-ion mass spectra at a single reflectron voltage. In this paper, we present results from this instrument for the amino acid sequencing of several peptides and describe the method of mass calibration.

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Collisionally activated dissociation (CAD) of the carboxylate anions, [M-H]-, or dilithiated cations, [M-H+2Li]+, from fatty acids results in charge-remote fragmentations at the alkyl chain C-C bonds leading to structure-indicative fragment ions. The neutral molecules eliminated during these reactions are characterized in this study using neutralization-reionization mass spectrometry (NRMS). The major neutral losses detected are alkenes (or dienes, in the case of monounsaturated fatty acids), not alkanes or alkyl radicals. This is consistent with the initially proposed mechanism proceeding by a pericyclic 1,4-elimination of H2.

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Collisionally activated dissociation (CAD) of the protonated polyalanines Ala-Ala,Ala-Ala-Ala, and Ala-Ala-Ala-Ala causes breakup of the peptide bonds leading to sequence-indicative fragment ions. The neutral molecules eliminated during these reactions are identified here using neutralization-reionization mass spectrometry (NRMS). N-terminal acylium ions (bn) arise after the C-terminus is lost as an intact amino acid or peptide; further loss of CO leads to immonium ions (an). Upon generation of C-terminal sequence ions (yn), a hydrogen atom attached to a nitrogen rearranges from the N-terminal to the C-terminal side yielding a protonated amino acid (y1) or peptide (y > or = 2) as the ionic fragment; the complementary neutral fragment is an aziridinone if the N-terminal amino acid is cleaved and a diketopiperazine if two N-terminal amino acid units are eliminated. Detection of neutral dissociation products can reveal valuable structure information, as demonstrated with the tetrapeptides Val-Gly-Ser-Glu and Val-Gly-Asp-Glu.

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