A Study of Households with Children and Firearms in Baltimore, Maryland.

Firearm injuries are the leading cause of death among children and adolescents in the US. Safe storage of firearms in the home is one of the most effective ways of preventing firearm injuries in children. This feasibility study was conducted in both the pediatric and general Emergency Departments of a large urban academic medical center in a community with high rates of firearm injuries in children.

Differentiation of the Aziridine Functionality from Related Functional Groups in Protonated Analytes by Using Selective Ion-Molecule Reactions Followed by Collision-Activated Dissociation in a Linear Quadrupole Ion Trap Mass Spectrometer.

Aziridines are commonly used as reagents for the synthesis of drug substances although they are potentially mutagenic and genotoxic. Therefore, their unambiguous detection is critically important. Unfortunately, tandem mass spectrometry (MS) based on collision-activated dissociation (CAD), a powerful method used for the identification of many unknown compounds in complex mixtures, does not provide diagnostic fragmentation patterns for ionized aziridines.

Proton Affinities of Alkanes.

Chemical characterization of complex mixtures of large alkanes is critically important for many fields, including petroleomics and the development of renewable transportation fuels. Tandem mass spectrometry is the only analytical method that can be used to characterize such mixtures at the molecular level. Many ionization methods used in mass spectrometry involve proton transfer to the analyte.

Study on the Gas-Phase Reactivity of Charged Pyridynes.

The reactivities of three isomeric, charged -pyridynes, the 1,2-, 2,3-, and 3,4-didehydropyridinium cations, were examined in the gas phase using Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry. The structures of selected product ions were probed using collision-activated dissociation (CAD) experiments in a linear quadrupole ion trap (LQIT) mass spectrometer. Mechanisms based on quantum chemical calculations are proposed for the formation of all major products.

Studies of the Fragmentation Mechanisms of Deprotonated Lignin Model Compounds in Tandem Mass Spectrometry.

Unlabeled and deuterium-labeled dimeric lignin model compounds with β-O-4 linkages were evaporated and ionized using negative ion mode electrospray ionization, transferred into a linear quadrupole ion trap, isolated, and subjected to collision-activated dissociation (CAD; MS experiments). The elemental compositions of the fragment ions were determined by using a high-resolution Orbitrap mass analyzer, and their structures were examined using further CAD experiments (MS experiments wherein = 2-5). Data analysis was facilitated by determining the fragmentation pathways for several deprotonated model compounds.

Fragmentation of Saturated Hydrocarbons upon Atmospheric Pressure Chemical Ionization Is Caused by Proton-Transfer Reactions.

Chemical characterization of complex mixtures of large saturated hydrocarbons is critically important for numerous fields, including petroleomics and renewable transportation fuels, but difficult to achieve. Atmospheric pressure chemical ionization (APCI) mass spectrometry has shown some promise in the analysis of saturated hydrocarbons. However, APCI causes extensive fragmentation to these compounds, which impedes its effectiveness.

Measurement of the Proton Affinities of a Series of Mono- and Biradicals of Pyridine.

The proton affinity (PA) of a neutral molecule is defined as the negative of the enthalpy change for the gas-phase reaction between a proton and the neutral molecule to produce the (charged) conjugate acid of the molecule. PA is a fundamental property that is related to the structure of a molecule and affects its reactivity. Very few PA values are available for basic organic monoradicals and none for biradicals.

Differentiation of Deprotonated Acyl-, -, and -Glucuronide Drug Metabolites by Using Tandem Mass Spectrometry Based on Gas-Phase Ion-Molecule Reactions Followed by Collision-Activated Dissociation.

Glucuronidation, a common phase II biotransformation reaction, is one of the major and metabolism pathways of xenobiotics. In this process, glucuronic acid is conjugated to a drug or a drug metabolite via a carboxylic acid, a hydroxy, or an amino group to form acyl-, -, and/or -glucuronide metabolites, respectively. This process is traditionally thought to be a detoxification pathway.

Polar Effects Control the Gas-Phase Reactivity of para-Benzyne Analogs.

We report herein a gas-phase reactivity study on a para-benzyne cation and its three cyano-substituted, isomeric derivatives performed using a dual-linear quadrupole ion trap mass spectrometer. All four biradicals were found to undergo primary and secondary radical reactions analogous to those observed for the related monoradicals, indicating the presence of two reactive radical sites. The reactivity of all biradicals is substantially lower than that of the related monoradicals, as expected based on the singlet ground states of the biradicals.

Selective increase in subtelomeric DNA methylation: an epigenetic biomarker for malignant glioma.

Background: Subtelomeric regions dynamically change their epigenetic pattern during development and progression of several malignancies and degenerative disorders. However, DNA methylation of human subtelomeres and their correlation to telomere length (TL) remain undetermined in glioma.

Results: Herein, we report on the selective changes in subtelomeric DNA methylation at the end of five chromosomes (Chr.