Ethanol-Induced Enhancement of Cocaine Bioactivation and Irreversible Protein Binding: Evidence Against a Role of Cytochrome P-450IIE1

Chronic ethanol consumption potentiates cocaine-induced liver injury in rodents. Since cocaine has to be bioactivated by a cytochrome P-450-dependent N-oxidative pathway to exert its hepatotoxic effects, we studied the role of the ethanol-inducible P-450IIE1 for cocaine metabolism. Male Sprague-Dawley rats were pretreated with either a liquid diet containing ethanol (30% of calories) for 4 weeks or injected with pyrazole (200 mg/kg/day, ip, for 3 days). Both agents induced microsomal p-nitrophenol hydroxylation which is a probe for the catalytic activity of P-450IIE1. However, only ethanol, but not pyrazole, increased both microsomal cocaine N-demethylase activity (by 47%) and the extent of irreversible binding of [3H]-cocaine to microsomal proteins (by 100%), which was taken as a quantitative endpoint for the formation of a reactive metabolite. Cocaine N-demethylation and irreversible protein binding of cocaine were not inhibited by P-450IIE1 isozyme-selective substrates, nor was the rate of cocaine metabolism and binding decreased by functionally active polyclonal anti-rat P-450IIE1 antibodies. Furthermore, pyrazole pretreatment sensitized cultured hepatocytes to the glutathione-dependent cytotoxic effects of nontoxic concentrations of cocaine. These results indicate that (a) cocaine is not a major substrate for the ethanol-inducible P-450IIE1, (b) the enhancing effects of ethanol on cocaine bioactivation may be due to induction of other P-450 isoforms, and (c) induction of P-450IIE1 may potentiate cocaine-induced hepatocellular toxicity in vitro independently of cocaine metabolism, e.g., by P-450IIE1-dependent oxidative stress.     

Recombinant cysteine proteinase from Leishmania (Leishmania) chagasi implicated in human and dog T-cell responses

High in vitro lymphoproliferative responses were induced in humans and dogs by a recombinant Leishmania (Leishmania) chagasi cysteine proteinase, with secretion of IFN-gamma in asymptomatic subjects or of IFN-gamma, interleukin 4 (IL-4), and IL-10 in oligosymptomatic subjects. In contrast, responses of symptomatic patients and dogs were lower, with production of IL-4 and IL-10.     

Antibody mediated CDCP1 degradation as mode of action for cancer targeted therapy

CUB-domain-containing-protein-1 (CDCP1) is an integral membrane protein whose expression is up-regulated in various cancer types. Although high CDCP1 expression has been correlated with poor prognosis in lung, breast, pancreas, and renal cancer, its functional role in tumor formation or progression is incompletely understood. So far it has remained unclear, whether CDCP1 is a useful target for antibody therapy of cancer and what could be a desired mode of action for a therapeutically useful antibody. To shed light on these questions, we have investigated the cellular effects of a therapeutic antibody candidate (RG7287). In focus formation assays, prolonged RG7287 treatment prevented the loss of contact inhibition caused by co-transformation of NIH3T3 cells with CDCP1 and Src. In a xenograft study, MCF7 cells stably overexpressing CDCP1 reached the predefined tumor volume faster than the parental MCF7 cells lacking endogenous CDCP1. This tumor growth advantage was abolished by RG7287 treatment. In vitro, RG7287 induced rapid tyrosine phosphorylation of CDCP1 by Src, which was accompanied by translocation of CDCP1 to a Triton X-100 insoluble fraction of the plasma membrane. Triggering these effects required bivalency of the antibody suggesting that it involves CDCP1 dimerization or clustering. However, this initial activation of CDCP1 was only transient and prolonged RG7287 treatment induced internalization and down-regulation of CDCP1 in different cancer cell lines. Antibody stimulated CDCP1 degradation required Src activity and was proteasome dependent. Also in three different xenograft models with endogenous CDCP1 expression RG7287 treatment resulted in significant tumor growth inhibition concomitant with substantially reduced CDCP1 levels as judged by immunohistochemistry and Western blotting. Thus, despite transiently activating CDCP1 signaling, the RG7287 antibody has a therapeutically useful mode of action.     

Effect of dentifrice containing fTCP,CPP-ACP and fluoride in the prevention of enamel demineralization

Objective: To evaluate the effect of different fluoride- and calcium- and/or phosphate-containing products on their ability to prevent enamel demineralization under pH cycling conditions.

Material and methods: Enamel bovine specimens were assigned to the following groups: G1-MPP (MI Paste Plus, 0.2% NaF, Recaldent?, GC Corporation Tokyo, Japan); G2-FD (Crest? Cavity Protection, 0.243% NaF, Procter &; Gamble, USA); G3-CLP (Clinpro? 5000, 1.1% NaF, 3M ESPE, USA); and G4-CO (Control without fluoride, Silica-based dentifrice; Daudt Ltda, Brazil). The specimens were soaked in demineralizing solution for 6?h and remineralizing solution for 18?h alternatively for 10 days. The toothpaste was prepared with deionized water in a 1:3 ratio (w/v) for three minutes daily. The solutions were renewed every 48?h. After cycling, enamel changes were analysed by percentage change of SMH (%SMH) and energy-dispersive X-ray spectroscopy (EDS). The %SMH value observed for G3-CLP (2.9?±?39.2) was higher than that found in G4-CO (?13.0?±?20.7), G1-MPP (?8.9?±?20.9) and G2-FD (?3.9?±?27.1). The %SMH was similar for all treatment groups (one-way ANOVA and Tukey’s HSD; p?2+ and P_total in the remineralization solutions were not different among all groups (Kruskal–Wallis; p?2+ concentration in the demineralization solution was significantly lower in G1-MPP. Ca²⁺ concentration increased in all groups after 48?h, except for G3-CLP. The EDX quantitative analysis showed that the atomic % of elements is lower level at G4-CO.

Conclusions: The Clinpro? 5000 demonstrated having the most protective effect against demineralization; however, the % SMH was similar for all groups.