The formation and persistence of the DNA adducts 7-(2'-oxoethyl)guanine (OEG) and N2,3-ethenoguanine (EG) were investigated in preweanling Sprague-Dawley rats exposed to vinyl chloride (VC). Lactating female CD rats with 10 day old pups were exposed to 600 p.p.m. VC by inhalation for 5 days, 4 h/day. Groups of rats were killed immediately and 3, 7 and 14 days after exposure. The concentrations of OEG and EG were measured in liver, lung, kidney, brain and spleen. HPLC with fluorescence detection was used for OEG detection, and gas chromatography-negative ion chemical ionization mass spectrometry was used for EG detection. In tissues of neonatal rats, the concentrations of both DNA adducts, expressed as pmol/mumols unmodified guanine, were highest in liver (OEG 162 +/- 36, EG 1.81 +/- 0.25), followed by kidney (OEG 29 +/- 1, EG 0.31 +/- 0.02), and lung (OEG 20 +/- 7, EG 0.21 +/- 0.08). No adducts were found in brain or spleen. DNA adducts were detected only in liver (OEG 43 +/- 7, EG 0.47 +/- 0.14) and lung (OEG 20 +/- 5, EG 0.27 +/- 0.03) of the dams. The ratio between EG and OEG was approximately 1:100 in all tissues immediately after exposure. In the liver of the preweanling rats, this ratio increased to 1:14 1 week after exposure, reflecting a greater persistence of EG. A half-life of 62 h was calculated for OEG, and the estimated half-life for EG was greater than 30 days. In view of the slow loss of EG and its high efficiency for causing base-pair mismatch, these results suggest that EG may be an important DNA adduct in VC-induced carcinogenesis.

Glycogen synthase kinase 3 regulates glycogen synthase, the rate-determining enzyme for glycogen synthesis. Liver and muscle glycogen synthesis is defective in type 2 diabetics, resulting in elevated plasma glucose levels. Inhibition of GSK-3 could potentially be an effective method to control plasma glucose levels in type 2 diabetics. Structure-activity studies on a N-phenyl-4-pyrazolo[1,5-b]pyridazin-3-ylpyrimidin-2-amine series have led to the identification of potent and selective compounds with good cellular efficacy. Molecular modeling studies have given insights into the mode of binding of these inhibitors. Since the initial leads were also potent inhibitors of CDK-2/CDK-4, an extensive SAR was performed at various positions of the pyrazolo[1,5-b]pyridazin core to afford potent GSK-3 inhibitors that were highly selective over CDK-2. In addition, these inhibitors also exhibited very good cell efficacy and functional response. A representative example was shown to have good oral exposure levels, extending their utility in an in vivo setting. These inhibitors provide a viable lead series in the discovery of new therapies for the treatment of type 2 diabetes.

ABSTRACT-Opioid receptor (MOR) agonism induces palatable food consumption principally through modulation of the rewarding properties of food. N-{ [3,5-difluoro-3Ј-(1H-1,2,4-triazol-3-ylis a novel opioid receptor inverse agonist that, on the basis of in vitro affinity assays, is greater than 10-or 50-fold selective for human or rat MOR, respectively, compared with -opioid receptors (KOR) and ␦-opioid receptors (DOR). Likewise, preferential MOR occupancy versus KOR and DOR was observed by autoradiography in brain slices from Long Evans rats dosed orally with the drug. GSK1521498 suppressed nocturnal food consumption of standard or palatable chow in lean and dietinduced obese (DIO) Long Evans rats. Both the dose-response relationship and time course of efficacy in lean rats fed palatable chow correlated with receptor occupancy and the plasma concentration profile of the drug. Chronic oral administration of GSK1521498 induced body weight loss in DIO rats, which comprised fat mass reduction. The reduction in body weight was equivalent to the cumulative reduction in food consumption; thus, the effect of GSK1521498 on body weight is related to inhibition of food consumption. GSK1521498 suppressed the preference for sucrose-containing solutions in lean rats. In operant response models also using lean rats, GSK1521498 reduced the reinforcement efficacy of palatable food reward and enhanced satiety. In conclusion, GSK1521498 is a potent, MOR-selective inverse agonist that modulates the hedonic aspects of ingestion and, therefore, could represent a pharmacological treatment for obesity and binge-eating disorders.

Human neutrophils or HL60 cells express P2U receptors and respond to micromolar concentrations of ATP, adenosine 5'-O-(thiotriphosphate) (ATPgammaS), or UTP with immediate increases in intracellular Ca2+ through activation of phosphoinositide phospholipase C (Cowen, D. S., Lazarus, H. M., Shurin, S. B., Stoll, S. E., and Dubyak, G. R. (1989) J. Clin. Invest. 83, 1651-1660). P2U agonists reportedly induce limited enzyme secretion and enhance the respiratory burst in response to chemotactic factors. We demonstrate here that P2U agonists are chemotactic for neutrophils or differentiated HL60 cells. Rhodamine phalloidin staining indicates that ATPgammaS treatment induces actin polymerization and shape changes similar to those seen when these cells are treated with chemotactic peptide fMet-Leu-Phe. Although undifferentiated HL60 cells fail to mount a rise in Ca2+ when challenged with fMet-Leu-Phe, they increase Ca2+ in response to P2U agonists. However, functional expression of phospholipase C-coupled receptors is not sufficient for chemotaxis since HL60 cell migration in response to these agonists or to fMet-Leu-Phe occurs only after exposure to differentiating agents such as BT2cAMP. In addition to the well known G protein-linked receptors for lipid or peptide chemotactic factors, neutrophils apparently also can utilize G protein-linked purino/pyrimidino receptors to recognize nucleotides as chemoattractants. High concentrations of ATP and UTP generated at sites of platelet aggregation and tissue injury could thus be important mediators of inflammation.