Free azoxy radicals from benzoquinolines

Conclusions The 5,6- and 7,8-benzo derivatives of 4-methyl-2-spirocyclohexyl-3,4 3,2-tetrahydrofurano-1,2,3,4-tetrahydroquinoline and their paramagnetic N-oxides were synthesized. A study was made of the paramagnetic absorption spectra of the free radicals, which are bezoquinoline derivatives.     

Extraction of interaction potentials from the elastic scattering amplitudes: an accurate quantum mechanical procedure

A quantum-mechanical method for obtaining the interaction potential from the elastic scattering amplitude is described. We present two examples in which nonmonotonic potentials possessing deep wells and strong repulsions are accurately determined.     

Formation of unsaturated bicyclic γ-butyrolactone by oxidative dimerization of 2-methyl-2-ethynylcyclopropanecarboxylic acid

Conclusions The oxidative dimerization of a mixture of the trans and cis isomers of 2-methyl-2-ethynylcyclopropanecarboxylic acid in the presence of CuCl and NH₄Cl gives, along with bis(trans-1-methyl-2-carboxyl-1-cyclopropyl)diacetylene (53% yield), also the corresponding dilactone, and specifically bi(1-methyl-4-oxo-3-oxabicyclo[3.1.0]-2-hexalidene)methyl (14% yield), which is probably formed via the intramolecular cyclization of the intermediately formed bis(cis-1-methyl-2-carboxy-1-cyclopropyl) diacetylene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1164–1166, May, 1981.     

Hyperoxygenation enhances the tumor cell killing of photofrin-mediated photodynamic therapy

Tumor hypoxia, either preexisting or as a result of oxygen depletion during photodynamic therapy (PDT) light irradiation, can significantly reduce the effectiveness of PDT-induced cell killing. To overcome tumor hypoxia and improve tumor cell killing, we propose using supplemental hyperoxygenation during Photofrin-PDT. The mechanism for the tumor cure enhancement of the hyperoxygenation-PDT combination is investigated using an in vivo-in vitro technique. A hypoxic tumor model was established by implanting mammary adenocarcinoma in the hind legs of mice. Light irradiation (200 J/cm2 at either 75 or 150 mW/cm2), under various oxygen supplemental conditions (room air, carbogen, 100% normobaric or hyperbaric oxygen), was delivered to animals that received 12.5 mg/kg Photofrin 24 h before light irradiation. Tumors were harvested at various time points after PDT and grown in vitro for colony formation analysis. Treated tumors were also analyzed histologically. The results show that when PDT is combined with hyperoxygenation, the hypoxic condition could be improved and the cell killing rate at various time points after PDT could be significantly enhanced over that without hyperoxygenation, suggesting an enhanced direct and indirect cell killing associated with high-concentration oxygen breathing. This study further confirms our earlier observation that when a PDT treatment is combined with hyperoxygenation it can be more effective in controlling hypoxic tumors.     

Steric mode of enzymic hydroxylation at primary carbon atoms: Hydroxylation of (1R)- and (1S)-[1-3H, 2H, 1H][1-14C]-octanes by Pseudomonas Oleovorans

(1R)- and (1S) [1-³H, ²H, ¹H]-octanes and mixed with [1-¹⁴C]-octane, were synthesized. The mixed samples were incubated with homogenats of P. oleovorans strain TF4-1L and the biosynthesized mixtures of octanols isolated. It was shown that mainly the achiral termini [-C¹H₃] were hydroxylated and that chiral methyls were oxygenated to the extent of 20–30%. In all instances the products derived from hydroxylation at the chiral methyls [-C-³H, ²H, ¹H] were mixtures of (1R)- and (1S)-octanols, the major component of which was the alcohol obtained by displacement of ¹H. The results indicate that hydroxylation proceeded with a normal isotope effect k_h>k_d>k_t. The amount of (1R)-octanol in the mixtures of octanols derived from (1R)- and (1S)-octane was determined. It was found that the C-1 hydroxylation of octane proceeded with retention, i.e. the incoming hydroxyl assumed the orientation of the displaced hydrogen (or isotopic hydrogen) atom.     

Affinity NMR: decoding DNA binding

We have shown that affinity NMR can be used to edit a NMR spectrum so that ligands that have affinity to DNA can be observed in the presence of other nonbinding molecules. Diffusion encoded spectroscopy (DECODES) can be used to identify the binding ligands. We were able to identify Hoechst 33342 as binding to the Drew-Dickerson dodecamer d(CGCGAATTCGCG)2 in the presence of the nonbinding molecules adenine, adenosine, and thiamine. Affinity NMR appears to be readily applicable to DNA systems for the following reasons. (1) The relaxation rate of the DNA oligonucleotides is favorable, thus the signal intensity loss due to relaxation is not severe. (2) A comparison of the patterns of the DNA cross-peaks upon binding in the two-dimensional total correlation spectroscopy and correlation spectroscopy spectrum are easily performed, and the ligand signals in the two-dimensional DECODES spectrum can be readily identified. (3) The aromatic part of the DNA spectrum is devoid of 2D cross-peaks in these correlation spectra, greatly facilitating the interpretation of the bound ligand in the DECODES spectrum.     

Dissociative electron transfer on ionic surfaces

A theory of electron transfer between adsorbed ions and electrically charged ionic surfaces is developed. Electron transfer from a charged AgBr surface to an Ag⁺ ion, as well as from Br^? ion to AgBr surface holes is studied. The Ag and Br atoms resulting from the process are shown to be dissociated from the surface.