Cinzia Arcelloni

Peripheral T cell tolerance occurs early during spontaneous prostate cancer development and can be rescued by dendritic cell immunization

In the tumor‐prone transgenic adenocarcinoma mouse prostate (TRAMP) mouse model we followed the fate of the immune response against the SV40 large T antigen (Tag) selectively expressed in the prostate epithelium during the endogenous transformation from normal cells to tumors. Young (5–7‐week‐old) male TRAMP mice, despite a dim and patchy expression of Tag overlapping foci of mouse prostate intraepithelial neoplasia, displayed a strong Tag‐specific cytotoxic T lymphocyte (CTL) response after an intradermal injection of peptide‐pulsed dendritic cells (DC). This response was weaker than the one found in vaccinated wild‐type littermates, and was characterized by a reduced frequency and avidity of Tag‐specific CTL. Early DC vaccination also subverted the profound state of peripheral tolerance typically found in TRAMP mice older than 9–10 weeks. The DC‐induced CTL response indeed was still detectable in TRAMP mice of 16 weeks, and was associated with histology evidence of reduced disease progression. Our findings suggest that tumor antigens are handled as self antigens, and peripheral tolerance is associated with in situ antigen overexpression and cancer progression. Our data also support a relevant role for DC‐based vaccines in controlling the induction of peripheral tolerance to tumor antigens.

High-performance liquid chromatographic determination of diclofenac in human plasma after solid-phase extraction.

A novel high-performance liquid chromatographic (HPLC) method for the quantification of diclofenac in human plasma was set up. Samples, added with ibuprofen (used as internal standard) were purified by solid-phase extraction using Abselut Nexus cartridges (Varian) not requiring pre-conditioning. Drugs of interest were eluted directly into the autosampler vials and injected. The recovery of diclofenac was 92%, the analysis lasted 7 min with a sensitivity of 5 ng/ml and intra- and inter-day RSDs of 3 and 8%, respectively. The pharmacokinetics of diclofenac after oral and rectal administration in 10 healthy volunteers are reported.

High-performance liquid chromatographic method for measuring total plasma homocysteine levels

We have modified a high-performance liquid chromatographic (HPLC) procedure based on SBD-F (ammonium-7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate) pre-column derivatization to obtain an assay that is useful for routine clinical total plasma homocysteine (tHcy) analysis. The introduction of easily handled sodium borohydride instead of the traditional tri-n-butylphosphine in dimethylformamide as a reductant and a 14-min run-time using basic isocratic HPLC equipment are the more notable advantages. The addition of mercaptopropionylglycine as an internal standard contributed to improvements in the reproducibility of the assay, yielding within- and between-run precisions of 1.9 and 4% (C.V.), respectively. Reference values for fasting tHcy were 7.65+/-2.3 and 8.9+/-2.4 micromol/l, while post-methionine load gave tHcy levels of 19.9+/-5.5 and 26.8+/-5.5 micromol/l, for women and men, respectively (n=40).

High-performance liquid chromatographic method with fluorescence detection for the determination of total homocyst(e)ine in plasma

A high-performance liquid chromatographic method for the determination of total plasma homocyst(e)ine [H(e)] after reduction with sodium tetrahydroborate and precolumn derivatization with o-phthaldialdehyde is described. The analyses, carried out on a reversed-phase C18 column, were based on spectrofluorimetric detection. The sensitivity was 1 pmol per injection and the intra- and inter-assay relative standard deviations were 1.8% and 5%, respectively. The plasma H(e) concentration determined in 40 healthy volunteers (20-60 years old) was 12.4 +/- 2.9 microM (mean +/- S.D.), in good agreement with reference values.

Structural determinants of CCR5 recognition and HIV-1 blockade in RANTES.

Certain chemokines act as natural antagonists of human immunodeficiency virus (HIV) by blocking key viral coreceptors, such as CCR5 and CXCR4, on the surface of susceptible cells. Elucidating the structural determinants of the receptor-binding and HIV-inhibitory functions of these chemokines is essential for the rational design of derivative molecules of therapeutic value. Here, we identify the structural determinants of CCR5 recognition and antiviral activity of the CC chemokine RANTES, showing that critical residues form a solvent-exposed hydrophobic patch on the surface of the molecule. Moreover, we demonstrate that the biological function is critically dependent on dimerization, resulting in the exposure of a large (∼180 Å2), continuous hydrophobic surface. Relevant to the development of novel therapeutic approaches, we designed a retroinverted RANTES peptide mimetic that maintained both HIV- and chemotaxis-antagonistic functions.

Enhancement of the HIV-1 inhibitory activity of RANTES by modification of the N-terminal region: dissociation from CCR5 activation

Although selected chemokines act as natural inhibitors of human immunodeficiency virus (HIV) infection, their inherent proinflammatory activity may limit a therapeutic use. To elucidate whether the antiviral and signaling functions of RANTES can be dissociated, several recombinant analogues mutated at the N terminus were generated and functionally compared with the wild‐type (WT) molecule, as well as with three previously described mutants. Substitution of selected residues within the N‐terminal region caused a marked loss of antiviral potency. By contrast, two unique analogues (C1.C5‐RANTES and L‐RANTES) exhibited an increased antiviral activity against different CXCR4‐negative HIV‐1 isolates grown in primary mononuclear cells or in macrophages. This enhanced HIV‐blocking activity was associated with an increased binding affinity for CCR5. Both C1.C5‐RANTES and L‐RANTES showed a dramatically reduced ability to trigger intracellular calcium mobilization via CCR3 or CCR5, while potently antagonizing the action of the WT chemokine. By contrast, two previously described analogues (RANTES3–68 and AOP‐RANTES) maintained a WT ability to trigger CCR5‐mediated signaling, while a third one (RANTES9–68) showed a dramatic loss of antiviral activity. These data demonstrate that the antiviral and signaling functions of RANTES can be uncoupled, opening new perspectives for the development of chemokine‐based therapeutic approaches for HIV infection.

Development and characterization of pituitary GH3 cell clones stably transfected with a human proinsulin cDNA

Successful β-cell replacement therapy in insulin-dependent (type I) diabetes is hindered by the scarcity of human donor tissue and by the recurrence of autoimmune destruction of transplanted β cells. Availability of non-β cells, capable of releasing insulin and escaping autoimmune recognition, would therefore be important for diabetes cell therapy. We developed rat pituitary GH3 cells stably transfected with a furin-cleavable human proinsulin cDNA linked to the rat PRL promoter. Two clones (InsGH3/clone 1 and 7) were characterized in vitro with regard to basal and stimulated insulin release and proinsulin transgene expression. Mature insulin secretion was obtained in both clones, accounting for about 40% of total released (pro)insulin-like products. Immunocytochemistry of InsGH3 cells showed a cytoplasmic granular insulin staining that colocalized with secretogranin II (SGII) immunoreactivity. InsGH3 cells/clone 7 contained and released in vitro significantly more insulin than clone 1. Secretagogue-stimulated insulin secretion was observed in both InsGH3 clones either under static or dynamic conditions, indicating that insulin was targeted also to the regulated secretory pathway. Proinsulin mRNA levels were elevated in InsGH3 cells, being significantly higher than in PTC3 cells. Moreover, proinsulin gene expression increased in response to various stimuli, thereby showing the regulation of the transfected gene at the transcriptional level. In conclusion, these data point to InsGH3 cells as a potential β-cell surrogate even though additional engineering is required to instruct them to release insulin in response to physiologic stimulations.

Determination of ceftazidime concentration in Mueller Hinton agar by high-performance liquid chromatography

A simple and rapid RP-HPLC method for the direct determination of ceftazidime (a β-lactam antibiotic) in agar (Mueller Hinton Agar-II) was developed. The method, characterised by good precision (C.V.</7.9%) and linearity in the 5–200 μg/ml range (r2⩾0.998), showed high recovery from agar (104±8%) and a sensitivity limit of 1.4 μg/ml. The analytical procedure allowed the determination of the “true” antibiotic concentration in the agar matrix. In addition, the small volume sample may allow a precise evaluation of the antibiotic levels point by point in the agar plates necessary to study the kinetics of diffusion of ceftazidime.

Pre-column derivatization of amino acids with N,N-diethyl-2,4-dinitro-5-fluoroaniline and reversed-phase liquid chromatographic separation

A new method for the separation and quantification of primary and secondary amino acids by reversed-phase high-performance liquid chromatography and spectrophotometric detection is described. The use of the novel derivatizing reagent N,N-diethyl-2,4-dinitro-5-fluoroaniline yields derivatives that are more stable to light and heat in solution than the traditional ones. A simple gradient between acidic acetate buffer and acetonitrile allows the complete separation of 21 amino acids in 80 min at room temperature. The good reproducibility of peak areas and retention times allows the application of this simple and low-priced method to the determination of amino acids in the range 50-500 pmol per residue.

Is the direct quantitation of antibiotics in agar by high-performance liquid chromatography useful?

The direct quantification of antibiotics in agar allows one to study the quality of the agar matrix, the kinetics of diffusion and the bacteria-antibiotic interaction. Mueller-Hinton agar (MHA) plates from three manufacturers were tested using HPLC and the disc diffusion test of ceftazidime (CAZ). Notable differences in the chromatographic profiles of MHA plate extracts from OXOID, DID and Becton Dickinson (BD) were shown, with a higher CAZ concentration after 24 h a 6 mm in BD P. aeruginosa inoculated plates (5.1 +/- 1.7 micrograms/ml, n = 6) vs. OXOID and DID (1.6 +/- 0.3 micrograms/ml, n = 12). BD plates gave also a different inhibition zone diameter (26 +/- 0.5 mm, n = 3) with respect to DID and OXOID (29 +/- 0.5 mm, n = 3).