RESUMO
We characterized a series of dimethylamino-stilbene derivatives as standards for time-domain and frequency-domain lifetime measurements. The substances have reasonable quantum yields, are soluble in solvents available with a high purity, and do not show significant sensitivity to oxygen quenching. All the fluorophores displayed single exponential intensity decays, as characterized by frequency-domain measurements to 10 GHz. The decay times vary from 880 to 57 ps, depending on structure, solvent, and temperature, which is a useful range for modern picosecond time-domain or gigahertz frequency-domain instruments. These fluorophores may be used either to test an instrument or as reference compounds to eliminate color effects. We also characterized two-fluorophore mixtures, with the decay times spaced twofold (150 and 300 ps), with varying proportions. These mixtures are useful for testing the resolution of other time- and frequency-domain instrumentation. The excitation wavelength ranges from 260 to 430 nm, and the emission from 350 to 550 nm. The decay times are independent of the excitation and emission wavelengths.
RESUMO
Utilizing established in vitro muscle contracture tests, we have identified three diagnostic contracture phenotypes for malignant hyperthermia susceptibility (MHS) among 103 patients. Phenotype H is an unequivocal diagnostic result for MHS, as is the nonsusceptible phenotype N. The third diagnostic group, phenotype K, represents an equivocal diagnostic response. To provide a basis for understanding relationships between contracture phenotypes and MHS, pigs with phenotypes H, K, and N were exposed to a standardized anesthetic protocol for assessing MHS. During the anesthetic challenge, phenotype H pigs developed a more severe form of the MH syndrome than did phenotype K pigs. Comparing phenotype H v K average responses, VO2 increased four- v twofold; lactate increased 13- v 9-fold; and temperature increased 41.7 degrees C v 39.2 degrees C, respectively. These values either had no change or decreased in the phenotype N pigs. Results of this study suggest that a spectrum of MHS exists among the human population.
