Between the devil and the deep blue sea: an unusual kind of late cardiac tamponade with a therapeutic dilemma.

A 67-year-old patient underwent a left pneumectomy because of a moderately differentiated squamous cell carcinoma. Two weeks later, while still in hospital, he suddenly experienced an acute increase in dyspnoea. Pulmonary embolism was considered. However, echocardiography showed compression of the right ventricle and right atrium by an intrapericardial mass, confirmed by computed tomography. Following signs of a large thrombus in the inferior vena cava, pericardiocentesis was considered undesirable due to possible dislocation resulting from the sudden changes in intrapericardial pressure. Re-thoracotomy was equally undesirable because of the recent operation and status of the patient. After stabilisation and extensive consulting the patient was referred for pericardiocentesis by sternotomy. Huge blood clots were removed from the pericardial space. No thrombus mass was found in the inferior vena cava. The patient recovered uneventfully.

Comparison of the repeatability of quantitative data measured in high-performance liquid chromatography with UV and atmospheric pressure chemical ionization mass spectrometric detection.

A detailed comparison of the repeatability of the retention times, the peak efficiencies and the peak areas of a dozen probe compounds achieved in HPLC, using either HPLC-UV or HPLC-MS for detection purpose, is reported. Three groups of conventional analytes, each one separated under a different set of experimental conditions, were selected for this study. Most of the compounds are basic, the other ones being neutral. The repeatabilities of the retention times do not exhibit any influence of the mode of detection. However, the repeatabilities of the peak areas and the column efficiencies are generally (although not always) better in HPLC-UV than that in HPLC-MS. On average, the precision for the UV peak area detection was 2.5% versus 6.8% for MS detection. Experimental results show that the response factor of the UV detector is more constant than that of the MS detector, probably because the HPLC flow-rate was sufficiently stable. The results obtained in the different tests are discussed.

Potassium nitrite reaction with 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in urine in relation to the drug screening analysis.

Recently potassium nitrite has been used as an adulterant to interfere with the analysis of 11-nor-delta 9-tetrahydro-cannabinol-9-carboxylic acid (THC-COOH) in urine. A comprehensive study of the THC-COOH and nitrite reaction chemistry and stability under various conditions is presented. Reverse phase high performance liquid chromatography (HPLC) and negative electrospray mass spectrometry (ESMS) results are given to substantiate the derived reaction mechanism and properties leading to reaction termination. The addition of potassium carbonate as a buffering agent prior to or following sample void as a means of preventing the formation of a nitroso-complexed form of the 11-nor-delta 9+-tetrahydrocannabinol-9-carboxylic acid is evaluated.

Synthesis and electrochemistry of anthraquinone-oligodeoxynucleotide conjugates.

Electroactive oligodeoxynucleotides (ODNs) with specific base sequences have a potential application as electrical sensors for DNA molecules. To this end, a phosphoramidite that bears a 9, 10-anthraquinone (AQ) group tethered to the 2'-O of the uridine via a hexylamino linker, 2'-O-[6-[2-oxo(9, 10-anthraquinon-2-yl)amino]hexyl]-5'-O-(4,4'-dimethoxytrityl)uridi ne 3'-[2-(cyanoethyl)bis(1-methylethyl)phosphoramidite] (3), has been synthesized and used to prepare three ODNs with tethered AQs using standard phosphoramidite chemistry. The synthetic methodology thus allows the synthesis of ODNs with electroactive tags attached to given locations in the base sequence. Cyclic voltammetric behavior of these AQ-ODN conjugates was examined in aqueous buffer solutions at a hanging mercury drop electrode. At slow sweep rates, nearly reversible two-electron waves characteristic of an adsorbed anthraquinone/hydroquinone redox couple was observed for all of the AQ-ODN conjugates. Approximate Langmuirian isotherms were found for the AQ-ODNs with molecular footprints, calculated from the saturation coverages, that scaled with molecular size. The cyclic voltammetric response of the duplexes formed from the AQ-ODNs and their complementary ODN was complicated by the competitive adsorption of the individual ODNs and possibly the duplex species as well.

Synthesis and Characterization of Molybdenum Carbide Clusters MonC4n, (n = 1 to 4).

Laser radiation (XeCl laser, 308-nanometer wavelength) focused into a cell containing Mo(CO)(6) vapor produced ultrafine particles in the extended waist of the laser beam. Negative ion mass spectrometry revealed molybdenum carbide cluster ions with a stoichiometry MonC4n (n = 1 to 4). The MonC4n(-) (n = 2 to 4) ions are completely unreactive with NH(3), H(2)O, and O(2), suggesting structures in which the molybdenum atoms are unavailable for coordination to additional ligands. Collision-induced dissociation studies of these anions show the loss of MoC(4) units as the main fragmentation pathway. This observation, together with the lack of addition reactions, provides a basis for structures in which a planar cluster of two, three, or four molybdenum atoms is surrounded by, and bonded to, carbon dimers.

Fast-atom bombardment-induced condensation of glycerol with ammonium surfactants II: Time dependence of mass spectra and tandem mass spectra.

Studies of fast-atom bombardment (FAB)-induced condensation between trimethyltetradecylammonium cations and glycerol have been extended to consider spectral time dependence. To enhance reproducibility of time dependence, a modified FAB target was used. FAB mass spectrometry of deuterium-labeled surfactants and FAB/collision-induced dissociation (CID) of nonlabeled material demonstrate that products of condensation at the surfactant "head group" predominate early in the analysis, while tail adducts become prominent later. This time dependence correlates with the expected surface activity of the products. It is incompatible with gas-phase reaction, but consistent with reaction in the condensed phase. Subtle variations in the surface activities of various condensation products (derived from changes in the number of hydroxyls from the reactive glycerol radical or in the position of attack along the surfactant chain) are reflected in the time dependence of FAB and CID spectra. CID spectra of deuterium-labeled cations provide evidence for intramolecular hydrogen transfer from the surfactant tail to the head within a surfactant radical. This transfer shows no significant kinetic isotope effect.

Structures of gas-phase C2F 7 (+) ions.

In an ion cyclotron resonance spectrometer, less than 96% of the C7F 7 (+) cation formed on electron ionization of perfluorotoluene reacts with hexamethyldisilazane. In contrast, the C7F 7 (+) from perfluoronorbornadiene or perfluorobicyclo[3.2.O]hepta-2,6-diene is nonreactive with hexamethyldisilazane. Collision-induced dissociation results support this dichotomy, although the evidence is not as clear-cut. The reactive ion is assigned the benzyl structure and the nonreactive ion the tropyl structure, on the basis of analogy with the protio cases. By AM1 calculations, the perfluorobenzyl ion is 25 kcal/mol more stable than the perfluorotropyl ion, the opposite of the situation for the protio analogs (- 12 kcal/mol). Ab initio calculations at the 3-21G level agree with the semiempirical energy difference to within 0.4 kcal/mol; at the more appropriate 6-31G*/MP2 level, the perfluorobenzyl cation is 9.7 kcal/mol more stable than the perfluorotropyl cation.

Fast atom bombardment-induced condensation of glycerol with ammonium surfactants. I: Regioselectivity of the adduct formation.

Fast atom bombardment promotes condensation between trimethyl tetradecyl ammonium cations and the glycerol matrix. Bond formation at both the head and tail of the surfactant is demonstrated by low energy collision-induced dissociation (ClD) of deuterium-labeled precursors, with a preponderance of the reaction apparently occurring at the tail. Two distinct ClD pathways are identified for each kind of adduct (head- and tail-attack). Evidence is presented for the detection of distonic radical cations of the surfactant, complexed (solvated) with glycerol.

Release of benzalkonium chloride from a heparin-bonded umbilical catheter with resultant factitious hypernatremia and hyperkalemia.

Elevated serum sodium and potassium levels were recently observed when sampled through a heparin-bonded umbilical catheter and measured with certain ion-selective electrodes. The cationic surfactant, benzalkonium chloride (BZC), is known to falsely elevate those cations in serum. Inasmuch as most heparin-bonded umbilical catheters use BZC during the bonding process, an in vitro study was performed to estimate the quantity of BZC released and the duration of sodium and potassium elevations during pooled sera infusion. Three heparin-bonded umbilical catheters and 3 silastic umbilical catheters were first flushed with 0.3 mL of normal saline and then perfused with pooled sera (sodium, 142 mEq/L; potassium, 4.6 mEq/L) at 2.5 microL/h. Effluent samples were collected from 0 to 8 hours and analyzed by ion-selective electrodes. Elevated serum sodium concentrations from 160 to greater than or equal to 250 mEq/L and potassium concentrations from 6.0 to greater than or equal to 9.6 mEq/L were observed. The BZC concentration in the catheter effluent was measured by mass spectrometry, with peak values of 10 micrograms/mL detected by this method. When varying concentrations of BZC (1 to 100 micrograms/mL) were added directly to pooled serum, a dose-dependent increase in serum sodium was observed. These data demonstrate that BZC released from heparin-bonded umbilical catheters elevates serum electrolyte values measured with some ion-selective electrodes. The observed increase in sodium and potassium concentrations may lead to clinical errors in management. Benzalkonium chloride is associated with myriad of linical symptomatology. Whether this amount of BZC is toxic in the small premature neonate is presently unknown.

Mass spectrometric signature of S-prenylated cysteine peptides.

The fast atom bombardment mass spectra of peptides containing S-prenylated cysteine display signature fragmentations characteristic of this modified amino acid. The fragmentation is independent of the nature of the cysteine carbonyl substituent, easily differentiates prenyl from nonprenyl alkylation, and readily identifies the oligomer count of the prenyl. This screening method, which requires little time, effort, or material (compared with previous analysis methods based on chemical degradation), greatly facilitates the identification of these prenylated proteins.

Analysis of the amino acid sequence of peptides by mass spectrometry. An ion notation proposal.

A new nomenclature is proposed that allows a precise and concise description of mass spectrometric fragments derived from peptides. The nomenclature differs from existing methods by specifically accommodating (1) extended or unusual amino acid residues, (2) cyclic- and cyclodepsipeptides, and (3) residues contained in branches of the main chain.

Solution-phase secondary-ion mass spectrometry of protonated amino acids.

Although sulfolane proved unexpectedly to be a poor solvent for solution-phase secondary-ion mass spectrometry of underivatized amino acids in the presence of thallium(I) salts, glycerol was somewhat more effective. Also, the addition of trifluoromethanesulfonic acid proved more effective than addition of the metal in generating molecular ion complexes. A convenient and reliable method for rapidly determining amino acid molecular ions is based on these observations.