Dietary energy restriction does not inhibit pancreatic carcinogenesis by N-nitrosobis-2-(oxopropyl)amine in the Syrian hamster

Dietary energy restriction was previously shown to be effective in preventing a wide range of experimentally induced cancers. Studies were conducted to assess the influence on pancreatic carcinogenesis of dietary energy restrictions (reduced fat and carbohydrate) of 10%, 20% or 40% in comparison with control in Syrian hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). Two carcinogenesis studies were conducted. One used a single treatment with 20 mg BOP/kg body weight and followed hamsters for 102 weeks following treatment, and the other used three weekly treatments of 20 mg BOP/kg body weight and followed hamsters for 45 weeks after treatment. Hamsters were fed control or energy restricted diet beginning the week following the last BOP treatment. Pancreatic carcinomas were induced in 9-18% of the hamsters in the first experiment and in 59-66% of the animals in the second. Dietary energy restriction did not influence carcinoma incidence in either study, and in the second experiment the multiplicity of tumors was higher in the 40% energy restriction (ER) group than in control hamsters. Plasma corticosterone was suppressed by BOP treatment, particularly in the 20% and 40% ER hamsters in the second experiment, and diet or BOP treatment did not significantly alter plasma cortisol. Pancreatic protein kinase Czeta measured by Western blot was highest in the cytosol and particulate fractions of the 40% ER hamsters in the first experiment. These results indicate that dietary energy restriction is not effective in the prevention of BOP induced pancreatic carcinogenesis in the Syrian hamster.     

Oxidized alpha2-macroglobulin (alpha2M) differentially regulates receptor binding by cytokines/growth factors: implications for tissue injury and repair mechanisms in inflammation

Alpha2M binds specifically to TNF-alpha, IL-1beta, IL-2, IL-6, IL-8, basic fibroblast growth factor (bFGF), beta-nerve growth factor (beta-NGF), platelet-derived growth factor (PDGF), and TGF-beta. Since many of these cytokines are released along with neutrophil-derived oxidants during acute inflammation, we hypothesize that oxidation alters the ability of alpha2M to bind to these cytokines, resulting in differentially regulated cytokine functions. Using hypochlorite, a neutrophil-derived oxidant, we show that oxidized alpha2M exhibits increased binding to TNF-alpha, IL-2, and IL-6 and decreased binding to beta-NGF, PDGF-BB, TGF-beta1, and TGF-beta2. Hypochlorite oxidation of methylamine-treated alpha2M (alpha2M*), an analogue of the proteinase/alpha2M complex, also results in decreased binding to bFGF, beta-NGF, PDGF-BB, TGF-beta1, and TGF-beta2. Concomitantly, we observed decreased ability to inhibit TGF-beta binding and regulation of cells by oxidized alpha2M and alpha2M*. We then isolated alpha2M from human rheumatoid arthritis synovial fluid and showed that the protein is extensively oxidized and has significantly decreased ability to bind to TGF-beta compared with alpha2M derived from plasma and osteoarthritis synovial fluid. We, therefore, propose that oxidation serves as a switch mechanism that down-regulates the progression of acute inflammation by sequestering TNF-alpha, IL-2, and IL-6, while up-regulating the development of tissue repair processes by releasing bFGF, beta-NGF, PDGF, and TGF-beta from binding to alpha2M.     

S 16924 ((R)-2-[1-[2-(2,3-dihydro-benzo[1,4] dioxin-5-yloxy)-ethyl]-pyrrolidin-3yl]-1-(4-fluoro-phenyl)-ethanone), a novel, potential antipsychotic with marked serotonin (5-HT)1A agonist properties: II. Functional profile in comparison to clozapine and haloperidol

S 16924 antagonized locomotion provoked by dizocilpine and cocaine, reduced conditioned avoidance responses and blocked climbing elicited by apomorphine, models predictive of control of the positive symptoms of schizophrenia: its median inhibitory dose (ID)50 was 0.96 mg/kg, s.c. vs. 1.91 for clozapine and 0.05 for haloperidol. Rotation elicited in unilateral, substantia nigra-lesioned rats by the D1 agonist, SKF 38393, and by the D2 agonist, quinpirole, was blocked equipotently by S 16924 (0.8 and 1. 7) and clozapine (0.6 and 2.0), whereas haloperidol preferentially blocked quinpirole (0.02) vs. SKF 38393 (1.8). S 16924 more potently inhibited the head-twitches elicited by 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and the locomotion provoked by phencyclidine than it inhibited the locomotion elicited by amphetamine (ID50s = 0.15 and 0.02 vs. 2.4). Clozapine showed a similar preference (0.04 and 0.07 vs. 8.6), but not haloperidol (0. 07 and 0.08 vs. 0.04). The discriminative stimulus (DS) properties of DOI were also blocked by S 16924 (ID50 = 0.17) and clozapine (0. 05) but not by haloperidol (>0.16). S 16924 fully (100%) generalized [effective dose (ED)50 = 0.7] to a clozapine DS and clozapine (0.23) fully generalized to a S 16924 DS whereas haloperidol (>/=0.08) only partially generalized (/=80.0) or clozapine (>/=80.0). Further, S 16924 (ID50 = 3.2) and clozapine (5.5) inhibited induction of catalepsy by haloperidol. This action of S 16924 was abolished by the 5-HT1A receptor antagonist, WAY 100,635 (0.16), which less markedly attenuated the anticataleptic action of clozapine. Further, although gnawing elicited by methylphenidate was inhibited by S 16924 (ID50 = 8.4), clozapine (19.6) and haloperidol (0.04), only the action of S 16924 was blocked by WAY 100,635 (0.16). Haloperidol potently (0.01-0.16, approximately 24-fold) increased prolactin levels whereas they were less markedly affected by S 16924 (2.5-40.0, 4-fold) and clozapine (10.0-40.0, 3-fold). Clozapine displayed high affinity at cloned, human, muscarinic (M1) and native, histamine (H1) receptors (Kis = 4.6 and 5.4 nM, respectively), whereas S 16924 (>1000 and 158) and haloperidol (>1000 and 453) displayed low affinity. In conclusion, S 16924 displays a profile of activity in diverse models of potential antipsychotic and extrapyramidal properties similar to that of clozapine and different to that of haloperidol. In particular, reflecting its partial agonist actions at 5-HT1A receptors, S 16924 inhibits rather than induces catalepsy in rats. However, in contrast to clozapine, S 16924 displays only low affinity for muscarinic and histaminic receptors.     

Mutation of residues in the C3dg region of human complement component C3 corresponding to a proposed binding site for complement receptor type 2 (CR2, CD21) does not abolish binding of iC3b or C3dg to CR2

Most evidence points toward there being a shared binding site in complement receptor type 2 (CR2, CD21) for the complement ligand C3dg and the EBV surface envelope glycoprotein gp350/220. Indeed, synthetic peptide studies have suggested that the CR2-binding sites in human C3dg and EBV gp350/220 share a similar sequence motif. The proposed CR2-binding sequence in C3dg is EDPGKQLYNVEA (residues 1199-1210 of mature C3), whereas that in EBV gp350/220 is EDPGFFNVEI (residues identical to C3dg are underlined). To further examine the role of amino acids 1199-1210 in the binding of the C3 fragments iC3b and C3dg to CR2, the following alanine-substitution variants of human C3 were tested in two independent CR2-binding assays: ED1199,1200AA; KQ1203,1204AA; L1205A; Y1206A; NV1207,1208AA; E1209A; and ED-KQ-NV1199,1200-1203,1204-1207,1208AA-AA-AA. Also engineered and tested was a chimeric C3 molecule in which the 1199-1210 sequence (PVPGGYQLTLEA) from the non-CR2-binding trout C3 molecule was grafted onto a human C3 background. Recombinant C3 proteins were expressed transiently in COS-1 cells, deposited as C3b on C3 convertase-bearing sheep erythrocytes and finally converted to cell-bound iC3b or C3dg using factors H and I. Binding of EAC423bi and EAC423dg to CR2 on Raji cells or EAC423dg to soluble CR2 was assessed. In most cases, the substitutions had little effect on CR2-binding activity and even in the case of the most highly substituted variants, the decrease in CR2-binding activity was less than twofold. Thus, contrary to the results anticipated from synthetic peptide studies, the single and multiple substitutions to the C3 sequence tested failed to corroborate a role for the 1199-1210 sequence in the C3dg-CR2 interaction.