Planimetric and histological study of the aortae in atherosclerotic chickens treated with nifedipine, verapamil and diltiazem.

Calcium appears to be involved in many of the cellular events which are thought to be important in atherogenesis. Calcium channel blockers have been shown to reduce arterial lipid accumulation in animals without altering serum cholesterol. Avian models of atherosclerosis offer economic and technical advantages over mammalian models. In this study, we examine the effects of nifedipine, verapamil and diltiazem at clinical and higher doses, on the extent of atherosclerosis of egg-fed chickens. In order to assess the extent of atherosclerosis quantitatively, the aortic lesions of the thoracic and abdominal aorta, aortic arch and supraaortic regions were measured by planimetry. Atherosclerotic lesions were evaluated histologically. Statistically significant reductions in the lipid deposition of the aorta were found in all the treated groups. The extent and distribution of atherosclerotic lesions were decreased in a significant way by verapamil, nifedipine and diltiazem. The higher the dosage used, the higher the regression of the atherosclerotic lesions. At clinical dosage, nifedipine showed the highest decrease of the lesions. In addition, the chicken atherosclerosis model has proved itself useful and very suitable for in vivo drug intervention studies.

Structural aspects, IR study, and molecular photophysics of the cumulene-bridged complexes with rhenium(I), ruthenium(II), and osmium(II) centers.

The synthesis of a series of ReI, RuII, and OsII complexes that contain rigid polyphosphine/cumulene spacers is reported here. These cumulenic ligands, namely, 1,1',3,3'-tetrakis(diphenylphosphino)allene (C3P4) and 1,1',4,4'-tetrakis(diphenylphosphino)cumulene (C4P4), utilize diphenylphosphino linkage components to coordinate to the metal-polypyridyl or metal-carbonyl units. Characterization of all mono-, homo-, and heterobimetallic complexes is achieved using 31P(1H) NMR, IR, and fast atom bombardment mass spectroscopy (FAB/MS) and elemental analysis. The two ReI homobimetallic complexes were also characterized by single-crystal X-ray structure determination, which provided the structural evidence of a 90 degrees rotation between the C3 and C4 adducts causing a change in the electrochemical behavior. The ground-state electronic absorption and redox interactions, along with the excited-state photophysical characteristics, are also explored. Electrochemical studies showed that an increase in the carbon chain length resulted in a greater amount of sigma-donation from the ligand to the metal centers, as well as a greater amount of electronic communication between the metal termini of the bimetallic species. The electronic absorption and emission spectra of the new complexes were also determined and characterized. The lifetimes of the excited-state luminescence of the ReI mono- and homobimetallic complexes were found to be an order of magnitude shorter than the lifetimes of the heterobimetallic complexes containing the RuII and OsII moieties. Excited-state energy transfer was observed from the higher MLCT excited state of the ReI centers to the lower energy MLCT excited state of the RuII and OsII centers on the following basis: no ReI-based emission was detected in the steady-state emission measurements, the time-resolved decay traces were fitted to only single-exponential decays, and the quantum yields were identical for each compound at two different excitation wavelengths where different percentages of the metal-based chromophores were excited.