Direct photooxidation of cyanine dyes was found to be markedly enhanced by formation of hypsochromically shifted (H) aggregates. Singlet oxygen was found to attack many cyanines possessing low oxidation potentials with rate constants in excess of lo8 / mol-I s-I. Singlet oxygen attack on 3,3'-diethyl-8,1O-dimethylthiacarbocyanine yields carbonyl products consistent with 1,2 addition to the 2,8 bond of the methine chain.

Aggressive malignant tumors may be diagnosed based on relative concentration of oxyhemoglobin and deoxyhemoglobin in the tumor microvasculature. Optoacoustic images of breast cancer and prostate cancer may be acquired at two laser wavelengths matching maximum of oxyhemoglobin (1064-nm, Nd:YAG laser) and deoxyhemoglobin (760-nm, Alexandrite laser). Two optoacoustic systems operating in forward and backward mode respectively for breast cancer and prostate cancer detection, employing arrays of ultravide-band piezoelectric transducers and multichannel electronics was described. After systems testing and calibration in phantoms, initial experiments were performed on patients with suspicious tumors. Quantitative analysis of two-color optoacoustic images was correlated with biopsy and histology. Possibility for tumor differentiation was demonstrated.

Articles you may be interested inGeneral theoretical formalism for describing the high-order effects of the dipolar coupling between spin-1/2 and quadrupole nuclei Apparatus and method for sideband suppression by variable low speed magicanglespinning nuclear magnetic resonance experiments Rev. Sci. Instrum. 66, 3994 (1995); 10.1063/1.1146421Field dependence of the magic angle spinning nuclear magnetic resonance line shapes of paired spin1/2 nuclei in solids Magic-angle spinning fails to eliminate the effect of dipolar coupling on the spectrum of a spin-l/2 nucleus (e.g., 13C ) coupled to a quadrupolar nucleus (e.g., 14N). A quantitative theory of this phenomenon, based on an adiabatic approximation, is presented, together with numerical simulations of spectra. The spectrum is sensitive to the sign and magnitude of the electric-field gradient at the quadrupolar nucleus, the angles between principal axes of the dipolar and quadrupolar interaction tensors, and the orientation of the spinning axis with respect to the external magnetic field.

A series of linear copolymers of DTPA-class Gd3+ conjugates, linked by alpha, omega-alkyldiamides with a varying number (n) of methylenes separating the amide function, were synthesized. Surprisingly, their relaxivities at all fields increased with increasing n. At MRI fields and 35 degrees C, the relaxivities of the n = 10 and n = 12 polymers were unexpectedly high, similar to those of rigid dendrimer-based Gd3+ chelates. The magnetic field dependence of solvent proton 1/T1 was measured for aqueous urea-free and urea-containing polymer solutions. The results for urea-free solutions imply an increase of rigidity (required for high relaxivities) with increasing n, arising from hydrophobic interactions of the methylene groups with solvent. This hypothesis is supported by a large decrease in the relaxivities upon addition of urea, which is known to weaken hydrophobic interactions. The relaxivities are also independent of polymer concentration, indicating that the hydrophobic interactions are intramolecular.