Effects of 1-ethynylpyrene and related inhibitors of P450 isozymes upon benzo[a]pyrene metabolism by liver microsomes

The effects of three aryl acetylenes, 1-ethynylpyrene (EP), 2-ethynylnaphthalene (EN) and 3-ethynylperylene (EPE), upon the metabolism of benzo[a]pyrene (BaP) by microsomes isolated from rat liver were investigated. These aryl acetylenes all inhibited the total metabolism of BaP. Formation of BaP 7,8-dihydrodiol and BaP tetrol products by microsomal preparations from rats that had been pretreated with 3-methylcholanthrene (3MC) were preferentially inhibited. The effects of EP upon the metabolism of BaP 7,8-dihydrodiol by microsomes from rat liver were also studied. This aryl acetylene strongly inhibited the formation of BaP tetrols from BaP 7,8-dihydrodiol by liver microsomes both from untreated rats and from rats pretreated with 3MC, but enhanced the conversion of the BaP dihydrodiol into other metabolites.     

Effects of d-amphetamine on behavior maintained by signaled and unsignaled delays to reinforcement

Four pigeons responded under a progressive-delay procedure. In a signaled-delay condition, a chained variable interval (VI) 30-s progressive time (PT) 4-s schedule was arranged; in an unsignaled-delay condition, a tandem VI 30-s PT 4-s schedule was arranged. Two pigeons experienced a signaled-unsignaled-signaled sequence; whereas, two pigeons experienced an unsignaled-signaled-unsignaled sequence. Effects of saline and d-amphetamine were determined under each condition. At intermediate doses (1.0 and 1.78 m/kg) delay functions were shallower, area under the curve was increased, and, when possible, break points were increased compared to saline; these effects were not systematically related to signaling conditions. These effects on control by delay often were accompanied by decreased response rates at 0 s. These results suggest that stimulus conditions associated with the delay may not play a crucial role in effects of d-amphetamine and other stimulants on behavior controlled by reinforcement delay.     

Morphological diversity of leaves of <Emphasis Type="Italic">Pseudoprotophyllum</Emphasis> (Platanaceae) from the Turonian-Coniacian of the northern coast of the Sea of Okhotsk

Fossil plants of the Chingandzha flora were studied from volcanogenic sediments of the Chingandzha and Rond formations on the northern coast of the Sea of Okhotsk. It was concluded that all platanaceous leaves earlier described in this flora as different taxa belong to one highly variable species, Pseudoprotophyllum cordatum Samyl. emend. Shczepetov et Golovneva.     

Does vinblastine add to the potency of alpha interferon in the treatment of renal cell carcinoma?

The combination of alpha interferon and vinblastine has been reported to yield a response rate of 30-40% in previously untreated patients with metastatic renal cell carcinoma. This combination was given to nine patients with advanced metastatic renal carcinoma after they failed or relapsed on alpha-interferon alone, to attempt to evaluate the role of vinblastine in this combination. Neither complete nor partial response was observed. Two patients had disease stabilization for two and seven months. Our preliminary results suggest that vinblastine did not add to the efficacy of interferon in this group of patients.     

Inactivation and oxidative modification of Cu,Zn superoxide dismutase by stimulated neutrophils: the appearance of new catalytically active structures.

Bovine superoxide dismutase (SOD) was inactivated during incubation with phorbol myristate acetate-stimulated neutrophils. In addition, stimulated neutrophils were able to disrupt the SOD structure. Inactivation and structural damage were dependent on the action of hypochlorous acid, an oxidant generated by the myeloperoxidase-hydrogen peroxide-chloride system of neutrophils. Incubation of SOD with stimulated neutrophils lead to long-wavelength fluorescence (ex, 350 nm; em, 450 nm) and the appearance of new structural forms with other isoelectric points. These additional forms possess catalytic activity. Generation of catalytically active new forms of SOD demonstrates the inaccessibility of the active centre of SOD to hypochlorite and may be a reason for the successful application of SOD during anti-inflammatory therapy.