Skeletal muscle fiber hypercontraction induced by Bothrops asper myotoxic phospholipases A ex vivo does not involve a direct action on the contractile apparatus.

Myonecrosis is a frequent clinical manifestation of envenomings by Viperidae snakes, mainly caused by the toxic actions of secreted phospholipase A (sPLA) enzymes and sPLA-like homologs on skeletal muscle fibers. A hallmark of the necrotic process induced by these myotoxins is the rapid appearance of hypercontracted muscle fibers, attributed to the massive influx of Ca resulting from cell membrane damage. However, the possibility of myotoxins having, in addition, a direct effect on the contractile machinery of skeletal muscle fibers when internalized has not been investigated.

Supercritical fluid extraction of vapor-deposited pyrene from carbonaceous coal stack ash.

The efficiencies of extraction of vapor-deposited pyrene from a high-carbon coal stack ash by Soxhlet extraction with methanol, ultrasonic extraction with toluene, acid pretreatment and subsequent ultrasonic extraction with toluene, batch extraction with toluene, and supercritical fluid extraction (SFE) are compared. SFE using CO(2) or isobutane yielded extraction recoveries virtually identical with those obtained using ultrasonic or Soxhlet extraction processes. Collection of the SFE extract was performed by expansion into a solvent or onto the head of a gas chromatography (GC) column.

Laser-induced site-selection matrix-isolation fluorescence spectrometry of dibenzacridine isomers.

Laser-induced matrix-isolation site-selection fluorescence spectrometry is used to obtain narrowed-line spectra, linear dynamic ranges and limits of detection for four isomeric dibenzacridines in argon at 15 K. Site-selection fluorescence is used to determine dibenzacridines in two synthetic mixtures, a four-component mixture of the isomeric dibenzacridines and a thirteen-component polycyclic aromatic hydrocarbon mixture. The capabilities of site-selection and Shpol'skii fluorescence spectrometry for the identification and determination of aza-arenes in complex mixtures are compared.

Determination of molecular nitrogen by electron-impact induced fluorescence.

When a sample of nitrogen gas is bombarded by 100-eV electrons, fluorescent emission from the nitrogen molecular ion, N(+)(2), is observed. The intensity of this fluorescence can be related to the pressure (or molar concentration) of the parent molecule, N(2). The limit of detection for N(2) by means of electron-impact induced fluorescence is 5.